EP0754974B1

EP0754974B1 - Multi-colour filter arrays for use in LCD and method for photographically producing said arrays

Info

Publication number: EP0754974B1
Application number: EP19960201957
Authority: EP
Inventors: Jean-Pierre C/O Agfa-Gevaert N.V. Tahon; Luc C/O Agfa-Gevaert N.V. Vanmaele; Herman C/O Agfa-Gevaert N.V. Van Gorp
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1995-07-21
Filing date: 1996-07-11
Publication date: 1999-04-28
Anticipated expiration: 2016-07-11
Also published as: DE69602234T2; JPH09211813A; DE69602234D1; EP0754974A2; EP0754974A3

Description

1. Field of the Invention

This invention relates to a photographic material suitable for use in the production of a multicolour filter array element, to such element and a multicolour liquid crystal display device incorporating such element.

2. Background of the Invention

Liquid crystal display devices are used nowadays in numerous applications such as clocks, household appliances, electronic calculators, audio equipment, etc.. There is a growing tendency to replace cathode ray tubes by liquid crystal display devices being favoured for their smaller volume and lower power consumption. In some applications like e.g. laptop computers and pocket TV's liquid crystal display devices are even without competition.

High definition television in its ultimate version will require screen diagonals exceeding 50 inch (see P. Plezhko in the periodical Information Display September 1991, Vol. 7 no. 9, p. 19 a.f.). Although not yet in existence CRT-based 50 inch screens can be expected to be very impractical because of their weight and size. Liquid crystal technology is basically able to produce high definition television (HDTV) screens with moderate weight and size.

Liquid crystal display devices generally include two spaced glass panels, which define a sealed cavity, which is filled with a liquid crystal material. The glass plates are covered with a transparent electrode layer which may be patterned in such a way that a mosaic of picture elements (pixels) is created.

Full colour reproduction is made possible by the use of a colour filter array element inside the liquid crystal display device.

Two addressing systems are used to drive the display : either a passive (also called intrinsic) system or an active (also called extrinsic) system.

According to the passive system in the liquid crystal device the two electrode layers are patterned in a regular array of stripes. The stripes on one plate are perpendicular to those on the other plate.

The application of a voltage across two opposing stripes causes a change in the optical properties of the liquid crystal material situated at the crossing point of the two stripes, resulting in a change of the light transmission through the energised picture element called pixel.

According to the active system, which greatly improves the performance of the liquid crystal display device, each pixel has its own individual microelectronic switch, which means that such a microswitch is connected to an individual transparent pixel electrode, the planar size of which defines the size of the pixel. The microswitches are individually addressable and are three-terminal or two-terminal switching elements.

Two-or-more-terminal switches are formed by thin film transistors (TFT). These transistors are arrayed in a matrix pattern on a glass plate which together with a glass plate carrying a transparent uniform (non-patterned) electrode layer forms a gap filled with the liquid crystal material.

With a diode or a similar two-terminal switching device the transparent electrode layer must be patterned.

To impart colour reproduction capability to the liquid crystal display device a colour filter array element is provided on one of the two glass plates. In an active matrix display, examples of which are described in US-A 5,081,004 and 5,003,302, this is usually the glass plate opposite the glass plate carrying the switching elements.

A colour filter array for full colour reproduction consists of red, green and bleu patches arranged in a given order. For contrast improvement the colour patches may be separated by a black contour line pattern delineating the individual colour pixels as e.g. given in US-A 4,987,043.

In order to prevent loss of effective voltage over the liquid crystal material the colour filter is preferably kept out of the electrical circuit which means that the transparent electrode is deposited on top of the colour filter array element.

Several techniques for making colour filter array elements have been described in the prior art.

A first widely used technique operates according to the principles of photolithography as e.g. in EP-A 0 138 459 and is based on photohardening of polymers e.g. gelatin. Dichromated gelatin, doped with a photosensitiser, is coated on glass, exposed through a mask, developed to harden the gelatin in the exposed areas and washed to remove the unexposed gelatin. The remaining gelatin is dyed in one of the desired colours. A new gelatin layer is coated on the dyed relief image, exposed, developed, washed and dyed in the next colour, and so on. By that wash-off and dying technique four complete operation cycles are needed to obtain a red, green and blue colour filter array having the colour patches delineated with a black contour line. As an alternative dyeable or coloured photopolymers are used for producing superposed coloured photoresists. In the repeated exposures a great registration accuracy is required in order to obtain colour filter patches matching the pixel-electrodes.

In a modified embodiment of said photoresist technique organic dyes or pigments are applied by evaporation under reduced pressure (vacuum evaporation) to form a coloured patttern in correspondence with photoresist openings [ref. Proceedings of the SID, vol. 25/4, p. 281-285, (1984)]. As an alternative a mechanical precision stencil screen has been used for patternwise deposition by evaporation of dyes onto a selected substrate as illustrated e.g. in Japan Display 86, p. 320-322.

According to a second technique dyes are electrodeposited on patterned transparent electrodes from a dispersion of curable binder polymers, dispersing agents and coloured pigments. For each colour a separate deposition and curing step is needed.

According to a third technique said red, green and blue dyes are deposited by thermal transfer from a dye donor element to a dye-receiving element, comprising a transparent support e.g. glass plate, having thereon a dye-receiving layer. Image-wise heating is preferably done by means of a laser or a high intensity light flash. For each colour a separate dye transfer step must be carried out.

According to a fourth technique as described e.g. in US-A 4,271,246, a method of producing a multicolour optical filter comprises the steps of

(1) exposing a photographic material comprising a support and a single i.e. one black-and-white silver halide emulsion layer to light through a first pattern;

(2) developing the exposed emulsion layer with a first coupler-containing colour developer to form a pattern of a first dye; then

(3) exposing an unexposed portion of said emulsion layer to light through a second pattern;

(4) developing the exposed area with a second coupler-containing colour developer to form a pattern of a second dye;

(5) repeating exposure and development to form patterns containing dyes of third and optionally subsequent colours, thereby to form colour patterns of at least two colours; and subjecting the product to a silver removal treatment after the final colour development step.

All the above described techniques have in common that they require at least three (four if the black contour pattern requires a separate step) treatment steps, and some of them require a very costly exposure apparatus to reach the desired level of registration.

By the large number of production steps and the required accuracy the manufacturing yields, i.e. the percentage of the colour filter array elements made in the factory which meet quality control standards, are exceptionally low.
The very costly investments could be brought down when the filter production could be simplified and yet high quality maintained.

When using a multilayer colour photographic silver halide material for multicolour filter production comparable to colour print film used in the motion picture film industry the above mentioned problems related to image registration and large number of processing steps can be avoided. From one colour negative an unlimited number of colour positives on film can be produced at a very high rate. Only one exposure for each positive is needed. A great number of exposed positives can be chemically treated at the same time in the same machine. This makes the whole process very attractive from the viewpoint of yield and investment. Such process operating with a negative colour image as original to form a complementary colour pattern on a glass substrate has been described already in published Japanese patent application (Kokai) 60-133427.

EP-A 0 396 824 relates to a process for the production of a multicolour liquid crystal display device comprising a liquid crystal layer essentially consisting of nematic crystals in twisted or supertwisted configuration or smectic C (chiral smectic) ferroelectric liquid crystals wherein the liquid crystal molecules are aligned in such a way that said layer shows an electrically controllable rotation of the polarisation plane of the light incident on the display. Said liquid crystal layer together with a multicolour filter element is arranged between front and rear transparent electrodes for altering pixelwise the electric field over the liquid crystal layer and said electrodes are associated respectively with a front and rear light polariser element. Said process comprises in consecutive order the steps of:

(1) providing a photographic print material that contains on a glass support a plurality of differently spectrally sensitive silver halide emulsion layers,

(2) subjecting said print material to a single step multicolour pixelwise exposure,

(3) colour processing said exposed print material producing thereby in each silver halide emulsion layer a differently coloured pixel pattern,

(4) coating said colour processed print material at its silver halide emulsion layer assemblage side with a hydrophobic water-impermeable organic resin layer, and

(5) depositing by vacuum-coating one of said electrodes on said organic resin layer serving as a covering layer for said silver halide emulsion layer assemblage.

So, before introducing said multicolour filter in the liquid crystal device the uppermost emulsion layer of the thus processed photographic print material is coated with a hydrophobic water-impermeable organic resin to form a covering layer of said resin thereon, and by vacuum-deposition on top of the thus-applied resin coating a transparent electrically conducting (electrode) layer is formed.

Said resin layer on top of the colour filter array provides a good planarity and prevents the release of volatile substances from the emulsion layer during vacuum-deposition e.g. by sputtering, of the transparent conducting layer. Usually a bake at 150 °C or even higher is needed to impart by curing a good impermeability to the resin layer.

In liquid crystal displays of the so-called twisted nematic (TN) type (as are the majority of active matrix liquid crystal displays) the transparent uniformly applied electrode and also the patterned electrode are covered with an alignment layer. This layer usually consists of a heat-cured polyimide resin. Rubbing this cured layer with e.g. a nylon cloth as e.g. in GB-A 1,505,192 in a given direction causes an orientation of the liquid crystal molecules near the surface of the layer in the rubbing direction.

From the preceding it is clear that the multicolour filter array element is subjected to rather severe heat treatment steps during the manufacture of the liquid crystal display element. These heating steps may not give rise to discolouration of the filter and dye fading.

Most dyes formed by a reaction based on the coupling of colour formers with oxidised colour developer of the p-phenylenediamine type have rather limited resistance to high temperatures and tend to become yellowish or brownish, while the blues turn to dark grey.

It has been established experimentally by us that thermal degradation of colour filters made by means of a multilayer colour photographic silver halide material incorporating colour couplers is attributed to two simultaneously occurring phenomena i.e. break-down of one or more of the composing dyes and colouration of the residual normally colourless colour couplers still present in the processed layers, as has also been set forth as a problem in JP-A 63-261361, wherein colour filters are handled at a temperature of 120°C or higher and wherein it is the object of the invention to have excellent film surface flatness and excellent heat resistance of color dye images, prepared through a simplified procedure.

The major contribution to colouration (yellowish or brownish) of colour filters prepared by silver halide colour photography based on colour coupling comes from the magenta-forming colour couplers of the pyrazolone type, which is representative of nearly all of the magenta colour couplers used in modern colour photographic materials. Furthermore said colour couplers can react with magenta dyestuffs derived from them thereby causing loss of magenta dye as has been set forth e.g. in (P.W. Vittum and F.C. Duennebier, J.Am.Chem.Soc., 72, 1536 (1950))
Apart from this particular phenomenon the break-down of dyes is primarily determined by their structure.

As has been described in EP-A No. 95200306, filed February 8, 1995, now EP-726492, the stability of the dyes, formed in a coupling reaction between a colour coupler and the colour developing substance in its oxidised form, is strongly improved due to the structure of the colour developing substance according to the general formula (I) claimed therein, represented by the structure

wherein, R¹, R², R³ each independently represents a substituted or unsubstituted alkylgroup or a substituted or unsubstituted arylgroup, or R¹ and R² or R³ and R² or R³ and R¹ or R³ and R⁷ or R³ and R⁵ or (R¹ or R²) and R⁵ or (R¹ or R²) and R⁷ together with the atoms to which they are attached represent the necessary atoms to form a ring system,
R⁴, R⁵, R⁶ and R⁷ each independently represents hydrogen, alkyl, aryl, halogen, nitro, cyano, alkoxy, aryloxy, alkylthio, arylthio, acylamino, sulphonylamino, ureido, alkoxycarboxylamino, carbamoyl, sulphamoyl, sulphonyl, amino, alkoxycarbonyl group, or (R⁴ and R⁵) or (R⁶ and R⁷) together with the atoms to which they are attached represent the necessary atoms to form a ring system.

In addition, in a preferred embodiment both R¹ and R² are lower alkyl groups, having between 1 and 6 C-atoms, more preferably C₁ to C₃ - alkyl groups, and in a further preferred embodiment R⁴, R⁵ and R⁷ are hydrogen, and each of R¹, R², R³ and R⁶ is either a methyl or an ethyl group.

It is clear however that the use of the well-know standard p-phenyleendiamines used in e.g. CD-1, CD-2, CD-3 and CD-4 processing developers is not excluded, although the result will remain inferior versus the one obtained in the developer wherein the colour developing structure described in EP-A No. 95200306, cited hereinbefore, is used.

Nevertheless from the 3 dyestuff types (yellow, magenta and cyan) produced on colour coupling with p-phenylene diamine type developers, though making use of the p-phenylene derivative according to the said formula (I), the cyan dyes remain the most susceptible to break down under thermal constraints, and that therefore it can be expected that thermal stability of the colour filter as a whole can be much improved by the choice of the cyan dye forming coupler.

The heat treatment of the colour filters incorporated in LCD is quite severe and the need for more stable dyes is still existing and hence the need for p-phenylenediamine derivatives giving more stable dyes after colour development.

A further requirement is the need for dimensional stability of the colour filters coated on a transparant support which is, to a great extend, dependent on the support on which the colour filters are coated and on the presence of certain (polymeric) compounds added to the layers, especially to the subbing layer coated thereon. Said dimensional stability is required as the colour filters are passing the whole manufacturing cycle, including the "baking" or "heating" cycle, as the said colour filters are present in the interior of the LCD device. It is thus required that the transparent supports shouldn't be shrinking during that procedure, nor in one, nor in two dimensions, that they should withstand treatments with etchants and that their optical transparency and optical isotropy or approximate isotropy should be retained.

3. Objects and Summary of the Invention.

It is an object of the present invention to provide a method for processing a silver halide colour photographic material, comprising at least three spectrally different sensitive silver halide emulsion layers, sensitive to blue, green and red light respectively, whereby a heat stable three colour image is formed on a transparent support having a high dimensional stability (minimum shrinking), a high optical isotropy and transparency.

It is another object of the present invention to provide a processing method for photographic material suited for a simplified production of a multicolour filter useful in the manufacture of a multicolour liquid crystal display device (multicolour LCD) which manufacture includes high temperature treatment steps and wherein said heat treatment does not substantially affect the colour quality of said multicolour filter.

It is a further object of the present invention to provide a multicolour filter array element firmly associated with a transparent electrode layer in a multicolour liquid crystal display device e.g. a multicolour active matrix LCD.

It is another object of the present invention to provide a process for the manufacture of a multicolour liquid crystal display device comprising a multicolour filter array element firmly associated with a transparent electrode layer.

Other objects and advantages will become clear from the detailed description and examples which are not limitative to the scope of the present invention as defined by the claims.

The objects of the present invention are realised by providing a method for manufacturing a multicolour filter array element, firmly associated with a transparent electrode layer in a multicolour liquid crystal display device, comprising the steps of:

(i) exposing a silver halide colour photographic print material comprising a plurality of spectrally sensitive silver halide emulsion layers, each of which are sensitive to a different region of the visible wavelength spectrum, on an optically transparent and isotropic or approximately isotropic, dimensionally stable support, by a single step multicolour pixelwise exposure,

(ii) colour processing said exposed print material producing thereby in each silver halide emulsion layer a differently coloured pixel pattern,

(iii) coating said colour processed print material at its silver halide emulsion layer side with a hydrophobic water-impermeable organic resin layer,

(iv) curing said organic resin layer by heating said layer at temperatures between 100 °C and 250 °C,

(v) depositing a transparent electrode layer on said organic resin layer and

(vi) coating an alignment layer on top of said transparent electrode layer,

characterised in that
in a red-sensitive emulsion layer of said print material wherein at least one cyan dye image forming coupler and at least one oilformer in an cyan dye image forming coupler dispersion, said cyan dye image forming coupler corresponding to the general formula (I),

representing a 2,5-diacylaminophenol-type colour coupler, wherein:

Z represents a hydrogen atom or a coupling off group,
X is a ballasting group of sufficient size rendering said colour coupler non-diffusing in an alkali-permeable layer of a photographic element,
Rⁿ, represents H, an electron withdrawing atom or group, an aliphatic or aromatic substituent, or a linking group corresponding to the formula -Q-Rf, wherein Q is -O-, -S-, or -SO2-, and wherein Rf is a short-chain group, containing at least one electron-withdrawing group,

with the proviso that at least one of Rⁿ represents an electron-withdrawing atom or group or an aliphatic or aromatic substituent or linking group bound to a short-chain group carrying at least one electron withdrawing atom or group,
and wherein n represents an integer having a value from 1 to 5;
coated on said optically transparent and isotropic or approximately isotropic, dimensionally stable support, before performing steps (iv), (v) and (vi),
after heat-treatment for 1 hour at 200°C a cyan-dye image density of at least 50 % versus the initial density before heating is measured;
in that after applying the said method of manufacturing the support remains optically transparent for at least 80 % at 570 nm, and in that the isotropic or approximately isotropic support is dimensionally stable in that the shrinkage after heating is less than 5 %.

Moreover a silver halide colour photographic print material is disclosed, said material comprising as a support an optically transparent and isotropic or approximately isotropic support which is characterised by a ratio of the elasticity modulus, measured in a perpendicular and in a parallel direction, of less than 1.3, said support being dimensionally stable in that the shrinkage after heat-treatment for 1 hour at 200°C is less than 5 %;
and a plurality of spectrally sensitive silver halide emulsion layers coated thereupon, each of which are sensitive to a different region of the visible wavelength spectrum, wherein a red-sensitive emulsion layer comprises at least one cyan dye image forming coupler present as an oilformer dispersion, wherein said cyan dye image forming coupler corresponding to the general formula (I), defined hereinbefore, is present in an oilformer dispersion.

4. Detailed Description of the Invention.

In the context of this invention by print material is meant a silver halide colour photographic material that is comparable to the colour print film used in the motion picture film industry.

The multilayer arrangement of hydrophilic colloid (gelatin containing) Iayers of the present multicolour print material must stick very firmly to the dimensionally stable substrate.
In a particular embodiment glass is used as a substrate e.g. borax glass, borosilicate glass, lime glass, potash glass, soda glass, crown glass, flint glass, silica-flint glass, chromium glass, zinc-crown glass or quartz glass and the glass support has e.g. a thickness in the range of 0.5 to 1.5 mm and more preferably in the range from 0.5 to 1.2 mm, said glass support having further a failure stress (under tensile stress) equal to or higher than 1 x 10⁷ Pa and an elasticity modulus (Young's modulus) being equal to or lower than 10 x 10¹⁰ Pa as has been set forth in EP-Application No. 94203517, filed December 5, 1994 now EP 716339.

The use of so-called subbing layers currently used in colour print film on a resin support depends on the nature of the support. So in the case of glass supports, the said subbing layers cannot be used due to the very different nature of the glass substrates. In that case a strong adhesion of the hydrophilic colloid multilayer arrangement to the glass support can be realised by means of a very thin subbing layer containing gelatin, a water-soluble inorganic silicon compound like e.g. sodium silicate (water glass) and a gelatin hardening agent. An equally strong adhesion can be obtained without a subbing layer by the addition to the first layer, which in a preferred embodiment is a gelatin-containing light-absorbing anti-halation layer, of an organic silicon compound such as an epoxysilane and a hardening agent for gelatin.

When said layer after being freshly coated is treated at a temperature in the range of 34 to 40 °C and at a relative humidity in the range of 70 to 85 % the adhesion of said subbing layer towards a gelatin-containing layer such as a gelatin-silver halide emulsion layer is much improved. Particularly suitable subbing layers on the basis of organic silicon compounds are described in US-A 3,661,584 and GB-A 1,286,467. Ways in which defects due to aggregate gel of silane coupling can be avoided have been disclosed in JP-A 06-198 033.

Liquid crystal polyester supports which are particularly suitable for use in the method according to this invention include isotropic transparent thermoplastic resins as e.g. polyethylene-terephtalate, a polyethylene naphthalate or a polyether sulphon support and especially those described in US-A's 5,385,704: 5,188,930; 5,108,666 and 5,270,160 and in EP-A's 0 619 516 and 0 651 287.

According to this invention especially preferred isotropic transparent supports, resistant to dimensional change at elevated temperatures are those comprising linear condensation polymers which have a glass transition temperature above 190°C, and more preferably above 220°C, such as polycarbonates, polycarboxylic esters, polyamides, polysulfonamides, polyethers, polyimides and the like and copolymers thereof as disclosed in US-A's 3,634,089; 3,772,405; 3,725,070 and 3,793,249 and 5,407,791 and EP-A 0 583 787. Further descriptions can be found in RD's 10119 and 10148, September 1972; RD 10613, February 1973; RD 11709, January 1974; RD 11833, February 1974; RD's 12046 and 12012, April 1974; RD 13455, June 1975; RD 17643, December 1978; and RD 308119, December 1989. More recent patents are brought together in an overview in RD 36544, chapt. XV, p. 531-532, september 1994.

Under the term "resistant to dimensional change" is understood that shrinkage at 200°C for 1 hour in all dimensions is less than 5 %, more preferably less than 1.5 % and still more preferably less than 1 %. "Normal supports" have a shrinkage of about 5-10 %. An example of a polyethylene terephthalate film having a width to shrink by 2 to 20 % is given in EP-A 0 639 792. In order to avoid such high procentual shrinking degree the said film should be thermofixed at a very high temperature (e.g. 240 °C) during a short period (e.g. about 10 s), followed by subjecting to a relaxation treatment as has been described in Research Disclosure 34458, December 1992.

Under the term "isotropic or approximately isotropic" is understood that the ratio of the elasticity modulus, measured in a perpendicular and in a parallel direction, should approximately be 1.0, and more specifically remain less than 1.3. For polyether sulphon, this value is approximately 1.0.

According to this invention, in order to improve the dimensional stability of the support, subbing layers, optionally improving antistatic properties, are used as disclosed in e.g. US-A's 5,232,825; 5,019,494; 4,990,434; 4,977,071; 4,965,180; 5,204,219; 5,194,347; 4,994,353; 4,954,430; 5,061,611 and EP-A's 0 529 697 and 0 466 124. Suitable additives for improving the dimensional stability of the photographic element coated thereon are i.a. dispersions of a water-soluble or hardly soluble synthetic polymer e.g. polymers of alkyl (meth)acrylates, alkoxy(meth)acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl esters, acrylonitriles, olefins and styrenes, or copolymers of the above with acrylic acids, methacrylic acids, α-β-unsaturated dicarboxylic acids, hydroxyalkyl (meth)acrylates, sulphoalkyl (meth)acrylates, and styrene sulphonic acids.

According to this invention the said supports are resistant to dimensional change at elevated temperatures of 100°C for at least 1000 hours, of 150°C for about 10 hours and even for more elevated temperatures of 180-200°C for about 1-2 hours. To get an acceptable time during which the said supports remain resistant to dimensional change, a temperature of 210°C should not be exceeded. It is clear that the required stability at those high temperatures during more than 1 hour is not corresponding to the one demanded from classical photographic, and, in particular, from classical silver halide colour materials.

In the patent literature many attempts have been described to reduce dark-fading instability and heat stability, which both have commonly been treated together as in US-A's 5,094,938; 5,200,305; 4,818,668; 5,084,375; 4,463,086; 4,617,255; 4,609,618; 4,532,2024,451,558; 4,463,086; 4,341,864 and EP-A 0 159 913.

It has been found in the method according to this invention that the heat stability of cyan dyes, formed by the reaction of a cyan-dye image forming coupler and a p-phenylene diamine type developer is enhanced by using a cyan-dye image forming coupler in the cyan-forming layer according to the general formula (I).

According to this invention, especially cyan-forming dyes corresponding to the general formula (I) representing a 2,5-diacylaminophenol-type colour coupler are preferred,

wherein:

with the proviso that at least one of Rⁿ represents an electron-withdrawing atom or group or an aliphatic or aromatic substituent or linking group bound to a short-chain group carrying at least one electron witdrawing atom or group,
and wherein n represents an integer having a value from 1 to 5.

Preferred examples of withdrawing atoms are halogen atoms, wherein F is the most preferred. Otherwise the most preferred electron withdrawing group is -CN.

Examples of cyan-dye image forming colour couplers which are very useful in accordance with the method of this invention have been described, in US-A 4,342,825 and EP-A 0 269 766, in US-P 4,342,825 cyan-forming phenol type colour couplers are disclosed comprising in the 2-position of the phenol a benzamido group carrying on the benzene nucleus of the benzamido group at least one -Q-Rf group wherein Q is -O-, -S-, or -SO2-, and Rf is a short-chain fluorine-containing group derived from hexafluoro-propylene or trifluorochloroethylene; in EP-A 0 269 766 2,5-diacylaminophenol-type colour couplers carrying a 3-chloro-2,2,3-trifluoropropionamido group are disclosed, said couplers being capable of forming a cyan indoaniline dye by reaction with an oxidised aromatic primary amino developing agent, characterised in that said 3-chloro-2,2,3-trifluoropropionamido group makes part of the acylamino substituent standing in the 5-position of the phenol.

In accordance with this invention a quite unexpected effect was the very important influence of the presence and of the amount of oilformer used in the corresponding oilformer dispersion made from the cyan dye image forming coupler. In the patent literature useful examples thereof have been described in US-A's 5,026,631; 5,008,179 and 5,057,408.

It has been found now that especially tricresylphosphate and phthalic acid esters e.g. dibutylphthalate, are particularly preferred oilformers used in the preparation of oilformer dispersions of dye image forming couplers, in particular the cyan dye image forming couplers according to this invention. Examples of other useful oilformers are given in US-A's 5,162,197 and 4,684,606 and in JP-A's 01023257, 01017051 and 01009454.

According to this invention dibutylphthalate and tricresylphosphate are especially preferred, more preferably in amounts by weight from 0.3 % to 30 % versus the amount of dye image forming couplers. Molar amounts of oilformer and dye are from 0.2 to 5 mmole/m². It should be noted that those oilformers are used in the preparation of oilformer dispersions wherein the suitable cyan image forming couplers are dispersed. This is opposite to the presence as a coating ingredient of oilformers as described e.g. in EP-A 0 380 223, wherein dye image forming couplers are not present in the colour forming layers of the colour filter material but in the developers. It should further be noted that in EP-A 0 615 161 no use was made of oilformers and that although compound Cl therein represents a cyan dye image forming coupler wherein electron withdrawing groups are present, an improvement was reached in keeping a high density to red light after heat treatment at 200 °C for at most 90 minutes, which is remarkably lower than the improvement reached in this invention wherein the presence of oilformer dispersions of cyan image forming couplers is an essential feature.

Among magenta dye forming couplers M-1 is a more preferred example.

Other examples of the said magenta dye forming couplers can be found in US-A's 4,710,453; 5,342,748; 4,665,015; 4,695,533; 5,066,575; 5,013,636.

As yellow dye image forming couplers preferably benzoylacetanilide compounds are useful. The said compounds are disclosed e.g. in US-A 4,777,123. Particularly preferred benzoylacetanilide compounds are those with purine or theophylline derivatives in the coupling position.

In a preferred embodiment the sequence wherein the different spectrally sensitive silver halide emulsion layers are applied on a glass support is the sequence that is described in EP-A 0 615 161.

The amount of colour coupler needed to obtain an optical density not higher than 2.5 at the maximum of spectral absorption of the dye formed can be determined by simple tests.

The amount of silver halide present in each colour coupler containing layer is adjusted preferably in such a way that in the strongest exposed regions the colour coupler is completely converted to dye during the colour development. This means that the molar equivalent ratio of silver halide to colour coupler in the print material should preferably be at least 10 % higher than 1.

A ratio of 1 in equivalent amounts means that for each mole of colour coupler present in the layer 4 or 2 moles of silver halide are added, depending on whether the colour coupler is of the 4- or the 2-equivalent type.

In the transformation of one mole of a 4-equivalent colour coupler into one mole of dye, 4 moles of oxidised colour developer are involved, which means that 4 moles of silver halide must be reduced. In the case of a 2-equivalent colour coupler only 2 moles of silver halide are needed for a complete conversion.

In current colour print films the amount of colour coupler and the silver halide/colour coupler ratio strongly deviate from the above described ratio because they serve quite different purposes, viz. they serve for continuous tone reproduction in which an excess of colour coupler is preferred for speeding up colour development and obtaining maximum densities more than 3.

In order to inhibit the diffusion of oxidised developing agent into neighbouring silver halide emulsion layers said layers are separated by an intermediary water-permeable colloid layer e.g. gelatin-containing layer, comprising a scavenging agent for oxidised developing agent. Suitable scavenging agents for that purpose are diffusion-resistant hydroquinone derivatives, preferably containing one or more aliphatic ballast groups having at least 6 carbon atoms. Such scavenging agents and their use are described e.g. in DE-A 3 545 611.

The silver halide emulsion layer may contain any type of light-sensitive silver halide emulsion e.g. an emulsion that forms a latent image primarily on the surfaces of the silver halide grains, or that forms an internal latent image predominantly in the interior of the silver halide grains. The emulsions can be negative-working emulsions e.g. surface-sensitive emulsions or unfogged internal latent image-forming emulsions, or positive-working emulsions e.g. direct-positive emulsions of the unfogged, internal latent image-forming type, the development of which is conducted with uniform light exposure or in the presence of a nucleating agent. Further are mentioned direct-positive emulsions of the pre-fogged type wherein during image-wise exposure chlorine, bromine and/or iodine is liberated which image-wise destroys the developable centres created during overall prefogging. Direct-positive emulsions need only one development as do negative emulsions.

Reversal silver halide emulsions are not prefogged. Their processing includes 2 development steps and a fogging step. The first development is carried out with a black-and-white developer whereby a negative black-and-white silver image is formed. The remaining silver halide is made developable by fogging, either physically (by exposure to light) or chemically. Upon subsequent colour development, bleaching and fixing a positive colour image is obtained.

By negative-working is meant that the density observed after processing is proportional to the exposure. By positive-working is meant that the silver halide emulsions yield upon exposure and development positive images i.e. the density is inversely proportional to the exposure.

The applied silver halide can be of the silver chloride, the silver chlorobromide, the silver bromide, the silver bromoiodide or the silver chlorobromoiodide type.

The silver halide can be surface sensitised. Noble metal, e.g. gold, middle chalcogen e.g. sulfur, selenium or tellurium, and reduction sensitisers, employed individually or in combination, are specifically contemplated. Typical chemical sensitisers are listed in Research Disclosure (RD) December 1989, item 308119, section III and in RD September 1994, item 36544, section IV.

The silver halide can be spectrally sensitised with dyes from a variety of classes, including the polymethine dye class, which includes the cyanines, merocyanines, complex cyanines and merocyanines (i.e. tri-, tetra-, and polynuclear cyanines and merocyanines) oxonols, hemioxonols, styryls, merostyryls, and streptocyanines; see said Research Disclosures 308119, section IV and 36544, section V.

Suitable vehicles for the emulsion layers and other layers of the print material are described in RD 308119, section IX, and RD 36544, section II, of said Research Disclosure. Brighteners and anti-foggants are described in RD 308119, sections V and VI, and in RD 36544, sections VI and VII respectively. Hardeners for gelatin have been described in RD 308119, section X.

As already mentioned hereinbefore colour filters for liquid cristal displays normally comprise a repeating pattern of coloured patches as in a mosaic pattern or may form a pattern of stripes. The coloured patches are preferably separated by a black contour line, which, according to the present invention, is formed by superposed area of the different emulsion layers wherein on colour-development cyan, magenta and yellow dye is formed respectively.

According to a preferred embodiment the reflections from the glass plate back into the multilayer arrangement are eliminated by the presence of a light-absorbing (anti-halation) layer between the glass substrate and the first photographic silver halide emulsion layer. This anti-halation layer must loose its light-absorbing properties during or after processing and become as clear as possible. To this end one or more dyes are present in said layer which dyes should be destroyed chemically in one or more processing liquids or simply be soluble in one or more of the processing liquids or in the rinse water and be washed out. It is advantageous to use anti-halation dyes of the non-diffusing type i.e. dyes that are insoluble in water and do not migrate to adjacent layers during manufacture. This is important when the dyes, due to their spectral or other properties, can change the photographic properties of the adjacent silver halide emulsion layers.

Yellow dyes of the non-diffusing type that may serve in decolourisable anti-halation layers for use in a multicolour print material according to the present invention are described in US-A 4,770,984.

Filter or anti-halation dyes may be present in one or more layers of the multilayer arrangement to decrease unwanted interlayer reflections and/or to improve the optical characteristics of individual layers. This practice is well known to those skilled in the art as e.g. from US-A 4,770,984 or EP-A 0 582 000.

The pixelwise exposure of the multicolour print material according to the present invention can be performed in several ways.

For example, the exposure may proceed in a single step through a multicolour master, in a plurality of steps with light of different colour (blue, green and red) through a pitchwise shiftable black-and-white mask or simultaneously or subsequently by means of pixelwise modulated laser beams of different colour, blue, green and red.

A convenient method for manufacturing the colour filters for use according to the present invention, especially in mass-production when a great number of them is needed, is to carry out the exposure in a single step through a multicolour master.

When used in conjunction with a negative type multilayer silver halide colour material the master must be a coloured negative master, whereas a coloured positive master is needed when a direct positive or reversal type multilayer silver halide colour material is involved.

A coloured negative master has predominantly yellow-, magenta- and cyan coloured pixels at the places corresponding respectively with the blue, green and red pixels on the colour filter array element.

In said single step exposure using a white light source the coloured master is in close or near contact with the multilayer silver halide colour material from which a colour filter should be made, the gelatin layers of both materials facing each other. By said single step exposure simultaneously latent images in the 3 light-sensitive differently spectrally sensitive silver halide emulsion layers are formed.

Deviation from the desired spectral transmission characteristics of the filter area may be corrected by inserting in the white light beam filters changing the proportion of red, green and blue transmitted by the multicolour master.

The negative and positive masters may be made by means of other recording materials than silver halide emulsion type materials.

For example, the multicolour master may be made by photolithography, vacuum-deposition or electrodeposition of dyes, thermal transfer of dyes, electro(photo)graphy with coloured toner or inkjet printing with coloured inks.

In most embodiments of colour development of the exposed printing material comprising colour couplers p-phenylenediamine type developing agents are used. In EP-A 0 459 210 derivates of p-phenylenediamine yielding dyestuffs with improved fastness to light are described. Such colour developing substances are therefore advantageously used in the production of colour filters subjected lateron to radiation and/or thermal treatment.

In a preferred embodiment the developer solution comprising a p-phenylene diamine derivative corresponds to the one disclosed in EP-A 0 726 492, which is used in accordance with the present invention to develop a print material that is used to form a multicolour filter array useful in the production of multicolour Liquid Crystal Displays (multicolour LCD's).

After processing the silver halide colour filter is covered with a protective resin layer which in the production of a multicolour filter associated with an electrode layer should be present.

Since gelatin is a hydrophilic polymer it contains still a small amount of water even after thorough drying.
Minor quantities of water may not enter the liquid crystal cell since they profoundly disturb the operation of the liquid cristal display. Moreover, during the application of the electrode layer by vacuum-deposition water or other volatile substance may not escape from the gelatin-containing layers and has to be kept blocked by a protective impermeable resin layer on top of the uppermost colour-developed silver halide emulsion layer of the colour filter. In the manufacture of a liquid crystal display according to the present invention heat-curable resins are used for producing said impermeable layer.

Examples of heat-curable organic resins and curing agents therefore are described by Ernest W. Flick in "Handbook of Adhesive Raw materials" - Noyens Publications - Park Ridge, New Jersey, USA (1982). Polyimide resins that can be heat-cured are e.g. the photocurable polyimide resins disclosed in US-A 4,698,295. Further are mentioned epoxy resins that can be heat-cured with amines thermally set free from an amine precursor e.g. ketimine which on reacting with water yields an amine [ref. The Chemistry of Organic Film Formers by D. H. Solomon, John Wiley & Sons, Inc. (1967), p.190].

The water-impermeable hydrophobic organic resin layer may be coated from a liquid composition containing (an) evaporatable solvent(s) or may be applied onto the processed multicolour material by lamination using e.g. a heat-curable layer sandwiched originally between a polyethylene film and a protective cover sheet analogously to the type of material described in J. Photogr. Sci., 18, 150 (1970).

The wet strength of the colour processed gelatin containing silver halide emulsion layer assemblage before coating with the organic resin layer in step (4) of the present invention statement can be greatly improved as described in published EP-A 0 396 824 by a treatment with an aqueous composition containing the self-cross-linking reaction product of :

(i) an epihalohydrin or an α-dihalohydrin,

(ii) a water-soluble polyamide, and

(iii) a water-soluble polyamine containing at least two nitrogen atoms separated by at least three carbon atoms and optionally also by at least one oxygen or sulphur atom and having at least two hydrogen atoms attached to different nitrogen atoms. Said self-cross-linking reaction product may form itself a water-impermeable hydrophobic organic resin layer serving as covering layer or as subbing layer for another outermost water-impermeable organic resin layer.

The preparation of the above defined self-cross-linking reaction product is given in GB-A 1 269 381, wherein said product is described for improving the wet strength of paper.

A transparent conductive layer forming the electrode layer is applied to the impermeable resin layer by known techniques e.g. a transparent indium tinoxyde (ITO) layer is applied by vacuum-deposition.

Although the multicolour filter array elements prepared according to the present invention are very well suited for the production of active matrix liquid crystal displays their use is not restricted to that type of displays. They can be incorporated likewise in passive matrix liquid cristal displays, especially in supertwisted nematic (STN), double supertwisted nematic (DSTN), retardation film supertwisted nematic (RFSTN), in ferroelectric (FLC), guest host (GH), polymerdispersed (PF), polymer network (PN) liquid crystal displays, and so on. They can further be incorporated in emissive displays like electroluminescent displays, CRT devices and in charge coupled device (CCD) cameras.

The following examples illustrate the present invention without however limiting it thereto.

EXAMPLES EXAMPLE 1

Following layers were coated in the order given on a polyester support having a thickness of 85 µm to form a colour photographic material.

Said polyester support was a colourless longitudinally and transversally stretched polyethylene terephtalate film support subbed on one side with a coating solution at a coverage of 130 m² per litre. The film was then heat-set while being kept under tension at a temperature of 220°C for about 10 seconds.

Determination of the ratio of the elasticity modulus in a perpendicular and in a parallel direction gave a value of 1.2. After heat setting the film was cooled.

Shrinkage after treatment of 1 hour at 200°C was 0.6 % in the lenght-direction and 1.2 % in the width-direction so that it can be concluded that the average shrinkage lays between 0.5 and 1 %.

The subbing procedure for the polyethylene terephtalate film resulted in the following layer composition per m² :

0.170 g of latex copolymer vinylidene chloride (88 wt%), methylacrylate (10 wt%) and itaconic acid (2 wt%),
0.06 g of latex copolymer of methylmethacrylate (47.5 wt%), 1,3-butadiene (47.5 wt%) and itaconic acid (2 wt%),
0.001 g polymethylmethacrylate-particles with an average diameter of 3.5 µm as a matting agent.

In an alternative experiment wherein polyethylene naphthalate was used, subbing was performed as has been described in EP-A 0 583 787.

Anti-halation layer

A non-diffusing yellow dye of formula YD, was dispersed in gelatin. The coverages of yellow dye YD and gelatin were 0.5 and 1.5 g/m² respectively.

Blue sensitive layer

A 100 % silver chloride emulsion with an average grain size of 0.4 µm was sensitised to blue light with a spectral sensitising agent of formula SB. A yellow dye forming coupler of formula Yl was added to this emulsion.
The amounts of silver halide, gelatin and colour coupler Y1 were 0.57, 3.30 and 1.0 g/m² respectively.

First intermediate layer

A substance of formula SD, capable of scavenging oxidised colour developing agent was dispersed in gelatin and coated at a coverage of 0.08 g SD/m² and of 0.77 g gelatin/m².

Green sensitive layer

A silver chloride-bromide (90/10 molar ratio) emulsion with an average grain size of 0.12 µm was sensitised to green light with a spectral sensitising agent of formula SG. A magenta dye forming coupler of formula M-1 was added to this emulsion.

The amounts of silver halide, gelatin and colour coupler M-1 were 0.71, 2.8 and 0.53 g/m² respectively.

Second intermediate layer

This layer has the same composition as the first intermediate layer.

Red sensitive layer

A silver chloride-bromide (90/10 molar ratio) emulsion with an average grain size of 0.12 µm was sensitised to red light with a spectral sensitising agent of formula SR. A cyan dye forming coupler of formula C-1 was added to this emulsion for the material MATL1. For the materials MATL2, MATL3, MATL4 and MATL5 compounds of the formulae C-2, C-3, C-4 and C-5, used as comparative cyan dye forming were added.
Amounts of silver halide, gelatin and colour coupler were 0.49, 4.5 and 0.95 g/m² respectively.

In these formulae C-1 to C-3 and C-5 are two-equivalent couplers, whereas C-4 is a four-equivalent coupler.

Yellow, magenta and cyan water-soluble dyes, acting as accutance dyes were present at an appropriate coverage in the blue, green en red sensitive layer respectively and hydroxytrichlorotriazine acting as hardening agent was present in the red sensitive layer at a coverage of 0.035 g/m².

Silver halide to colour coupler ratios in equivalent amounts were about 1.2 for the three light-sensitive layers of the material. The coverages of the blue, the green and the red couplers, expressed in mmoles/m² were 1.4, 0.9 and 1.1 respectively.

Exposure.

Three sheets of material were given a white light exposure sufficient to produce by the colour processing as described hereinafter a black density of 2.50.

Developing.

The sheets of material were developed in the developer comprising as developing compound 4-amino-3-methyl-N-ethy-N-isopropylaniline hydrochloride as developing compound, the composition of the developer being given hereinafter.

Sodium sulphite (anhydrous)	4 g
4-amino-3-methyl-N-ethyl-N-isopropylaniline hydrochloride	3 g
sodium carbonate (anhydrous)	17 g
sodium bromide	1.7 g
sulphuric acid 7 N	0.62 ml
ethanol	50 ml
water up to	1000 ml

After development the sheet material was treated in an acidic stop bath prepared by adding water up to 1 l to a volume of 50 ml of sulphuric acid 7 N.

The treatment with stop bath was followed by 2 minutes rinsing in plain water followed by a 2 minutes fixing in an aqueous solution having the following composition :

58 % aqueous solution of (NH₄)₂S₂O₃	100 ml
sodium sulphite (anhydrous)	2.5 g
sodium-hydrogen sulphite (anhydrous)	10.3 g
water up to	1000 ml

The treatment with fixing liquid was followed by a 2 minutes rinsing in plain water followed by a 3 minutes bleaching in an aqueous solution having the following composition :

potassium hexacyanoferrate (III) (anhydrous)	30 g
sodium bromide (anhydrous)	17 g
water up to	1000 ml

Thereupon each sheet was treated with the fixing liquid again and rinsed for 3 minutes with plain water.

Finally each sheet was treated with an aqueous solution having a pH of 9 and containing per liter 20 ml of a 40 % aqueous solution of formaldehyde serving as hardening agent.

The sheets were submitted to a heat treatment at 200°C during 60 minutes. The cyan density for different densities (maximum density. density D=1.0 and density D=0.5), remaining after the heat-treatment and expressed as percentages of the initial density, are given in the following Table 1. The total density originally found is also given in the same Table 1.

Sheet	Dmax	D=1.0	D=0.5	D
MATL1 ("inv.")	78 %	63 %	63 %	2.11
MATL2 (comp.)	14 %	18 %	28 %	1.88
MATL3 (comp.)	12 %	18 %	29 %	2.05
MATL4 ("inv.")	65 %	51 %	48 %	1.55
MATL5 ("inv.")	64 %	51 %	38 %	1.25

It is clear that the heat stability of the cyan colour generated during colour development from a cyan dye forming coupler according to the general formula I, having electron-withdrawing atoms like F in C-1 and Cl in C-5 or electron-witdrawing groups like -CN in C-4 and C-5 in its structure, is remarkably better for all densities than for cyan colours lacking the presence of electron-withdrawing atoms or groups. This corresponds with the situation set forth in EP-A 0 615 161, except for the specific characteristics of the support according to this invention. In this Example the advantages offered by this invention are not yet fully illustrated as cyan dye image-forming couplers have been dispersed herein in the absence of oilformers (as a consequence we have written in the Table 1 "inv.").

EXAMPLE 2

Materials having the same composition were coated as in Example 1, except for the cyan dye forming coupler used in the red-sensitive layer. So for the material MATL6 compound C-1 was added to this emulsion, but the cyan dye forming coupler was dispersed together with dibutylphthalate (DBP) as an oilformer in an amount of 10% by weight. For the materials MATL7, MATL8 and MATL9 cyan dye forming couplers of the formulae C-6, C-7 and C-8 were added, wherein each of the dispersions of the cyan dye forming couplers were also containing dibutylphthalate as an oilformer in an amount of 10 wt%. The cyan dye image forming couplers C-6, C-7 and C-8 all have F-atoms in their chemical structures as shown hereinafter, which, according to the results shown in Table 1 should be favourable for heat stability. MATL10, indicated as "comparative" differs from MATL6 in that no oilformer is used in the dispersion of compound C-1.

C-6, C-7 and C-8 have F as electron-withdrawing atom.
C-6 is a 4-equivalent and C-7 and C-8 are 2-equivalent couplers.

The sheets coated onto the same support as in Example 1 were submitted to a heat treatment at 200°C during 60 minutes in the same way as in Example 1. The cyan density for different densities (maximim density, density D=1.0 and density D=0.5), remaining after the heat-treatment and expressed as percentages of the initial density, are given in the following Table 2, together with the total cyan density originally measured after processing.

Sheet	Dmax	D=1.0	D=0.5	D
MATL6 (inv.)	78 %	70 %	60 %	2.09
MATL7 (inv.)	74 %	70 %	73 %	1.81
MATL8 (inv.)	82 %	79 %	79 %	1.93
MATL9 (inv.)	67 %	65 %	64 %	1.23
MATL10(comp.)	56 %	47 %	43 %	1.65

It is confirmed in Table 2 that the heat stability of the cyan colour generated during colour development from a cyan image dye forming coupler according to the general formula I, having electron-witdrawing atoms in its structure, is good, but differs from the nature of the cyan dye forming coupler. Moreover it is clear that the presence of an oilformer in the dispersion of the said coupler is further in favour of heat stability.

EXAMPLE 3

Therefore in Example 3 the influence of the nature of the oilformer on the heat stability of cyan dye forming coupler C-1 was studied. The following oilformers were used in making a dispersion of C-1: oilformer 0-12 being dibutylphtalate (dispersion of C-1 coated in MATL11, coated as described in Example 1); oilformer 0-12 (MATL12); oilformer 0-13 tricresylphosphate (MATL13); 0-14 (MATL14); and 0-15 (MATL15). The formulae of the corresponding oilformers 0-12 to 0-15 are given hereinafter. MATL10 was used as a comparative (no oilformer present).

The sheets were submitted to a heat treatment at 200°C during 60 minutes just as in Example 1. The cyan image density for different densities (maximim density, density D=1.0 and density D=0.5), remaining after the heat-treatment and expressed as percentages of the initial density, are given in the following Table 3, together with the total cyan density originally measured after processing as described in Example 1.

Sheet	Dmax	D=1.0	D=0.5	D
MATL11(inv.)	77 %	71 %	62 %	1.99
MATL12(inv.)	82 %	79 %	80 %	1.60
MATL13(inv.)	84 %	82 %	84 %	1.82
MATL14(inv.)	72 %	77 %	81 %	1.20
MATL15(inv.)	76 %	74 %	80 %	2.05
MATL10(comp.)	58 %	50 %	45 %	1.73

As can be seen from Table 3 the nature of the oilformer used in the dispersion of the cyan dye image forming compound is determining its heat stability. From this table it can be derived that for all densities, every oilformer causes a substantial improvement. Tricresylphosphate and dibutylphthalate however are preferred to reach the objects of this invention.

EXAMPLE 4

In Example 4 the influence of the nature of the developer on the loss in density after the heat stability test of the cyan dye image forming coupler C-1 was studied. Therefore the same materials as in Example 3 were developed in a developer comprising as developing compound 4-amino-3-methyl-N,N-diethylaniline hydrochloride instead of 4-amino-3-methyl-N-ethyl-N-isopropylaniline hydrochloride as developing compound, the composition of the developer being given hereinafter.

Sodium sulphite (anhydrous)	4 g
4-amino-3-methyl-N,N-diethylaniline hydrochloride (CD-2)	3 g
sodium carbonate (anhydrous)	17 g
sodium bromide	1.7 g
sulphuric acid 7 N	0.62 ml
ethanol	50 ml
water up to	1000 ml

After development the sheet material was treated further just as in Example 1.

The sheets were submitted to a heat treatment at 200°C during 60 minutes just as in Example 1. The cyan dye image density for different densities (maximum density, density D=1.0 and density D=0.5), remaining after the heat-treatment and expressed as percentages of the initially measured density, are given in the following Table 4, together with the total cyan density originally measured after the applied processing characterised by the presence of the developing agent as set forth hereinbefore. Dmax and % density remaining after development in the developer used for Example 3 are added to make a comparison more easy.

Sheet	Dmax	D=1.0	D=0.5	D	Dmax (comp)	D (comp.)
MATL11(inv.)	74 %	55 %	52 %	2.11	77 %	1.99
MATL12(inv.)	71 %	65 %	65 %	1.81	82 %	1.60
MATL13(inv.)	78 %	69 %	64 %	1.97	84 %	1.82
MATL14(inv.)	66 %	70 %	70 %	1.36	72 %	1.20
MATL15(inv.)	76 %	60 %	61 %	2.06	76 %	2.05
MATL10(comp.)	27 %	26 %	32 %	1.50	58 %	1.73

As can be seen from Table 4 the nature of the developing agent is determining the heat-stability. Although the well-known CD-2 developing p-phenylene diamine derivative acts sufficiently according to this invention, the developing agent corresponding with the invention described in EP-A No. 95200306, filed February 8, 1995, now EP-726492, acts better. Differences measured between the materials are completely similar with differences given in Example 3. The same conclusions can thus be drawn.

Apart from the heat-stability of the cyan dye image forming coupler the light-stability was tested. Therefor the "suntest" was applied to the same materials MATL10 (comparative) and MATL11-MATL15 (invention), , developed in CD-2 (developer called "CD2" in Table 5) and in the developer called "LCD2" (developing agent described in EP-A No. 95200306, filed February 8, 1995, now EP-726492). MATL12 and MATL15 is not present herein, due to an experimental failure.

The so-called "suntest" consists in exposure during 100 hours of developed material with light of a low pressure Xenon lamp NXe 1500, manufactured by HERAEUS, filtered with a L393-filter. The illuminance realised with the said Xenon lamp was 110 kLux; the integral irradiance was 414.5 W/m² (without filter in the wavelength region between 300 and 830 nm).

The cyan density remaining after the irradiation-treatment of the developed material and expressed as a percentage of the initial density, for different densities (maximum density Dmax, density D=1.0 and density D=0.5) is given in the following Table 5.

Sheet	Dmax CD2	D=1.0 CD2	D=0.5 CD2	D CD2	D LCD2	Dmax LCD2	D=1.0 LCD2	D=0.5 LCD2
MATL11	61 %	65 %	72 %	1.84	1.81	91 %	89 %	83 %
MATL13	64 %	65 %	67 %	1.82	1.56	85 %	84 %	80 %
MATL14	58 %	61 %	59 %	1.29	1.12	81 %	81 %	78 %
MATL10	49 %	56 %	67 %	1.37	1.84	81 %	79 %	83 %

As can be seen from Table 5 the colour developing agent used in the colour processing has a strong influence on the light-stability of the processed material: LCD2 acts much better than CD2!

Although the CD-2 developing p-phenylene diamine derivative acts sufficiently according to this invention, especially under the influence of oilformers as dispersing agents for the cyan dye image forming couplers the developing agent corresponding with the invention described in EP-Application No. 95200306, filed February 8, 1995, now EP-726492, acts better again. The effect on heat stability was already convincingly demonstrated in the said EP-Application.

Differences in percentages of the original cyan density after development, retained after the said "sun test" and measured between the different materials are completely similar with differences given in the Tables 3 and 4, related with heat-stability. The same conclusions can thus be drawn for both light-stability and heat-stability.

Claims

Method for manufacturing a multicolour filter array element, firmly associated with a transparent electrode layer in a multicolour liquid crystal display device, comprising the steps of:

(i) exposing a silver halide colour photographic print material comprising a plurality of spectrally sensitive silver halide emulsion layers, each of which are sensitive to a different region of the visible wavelength spectrum, on an optically transparent and isotropic or approximately isotropic, dimensionally stable support, by a single step multicolour pixelwise exposure,

(ii) colour processing said exposed print material producing thereby in each silver halide emulsion layer a differently coloured pixel pattern,

(iii) coating said colour processed print material at its silver halide emulsion layer side with a hydrophobic water-impermeable organic resin layer,

(iv) curing said organic resin layer by heating said layer at temperatures between 100 °C and 250 °C,

(v) depositing a transparent electrode layer on said organic resin layer and

(vi) coating an alignment layer on top of said transparent electrode layer.

characterised in that
in a red-sensitive emulsion layer of said print material wherein at least one cyan dye image forming coupler and at least one oilformer in an cyan dye image forming coupler dispersion, said cyan dye image forming coupler corresponding to the general formula (I),
representing a 2,5-diacylaminophenol-type colour coupler, wherein:

Z represents a hydrogen atom or a coupling off group,

X is a ballasting group of sufficient size rendering said colour coupler non-diffusing in an alkali-permeable layer of a photographic element,

Rⁿ, represents H, an electron withdrawing atom or group, an aliphatic or aromatic substituent, or a linking group corresponding to the formula -Q-Rf, wherein Q is -O-, -S-, or -SO2-, and wherein Rf is a short-chain group, containing at least one electron-withdrawing group,

with the proviso that at least one of Rⁿ represents an electron-withdrawing atom or group or an aliphatic or aromatic substituent or linking group bound to a short-chain group carrying at least one electron withdrawing atom or group,
and wherein n represents an integer having a value from 1 to 5;
coated on said optically transparent and isotropic or approximately isotropic, dimensionally stable support, before performing steps (iv), (v) and (vi),
after heat-treatment for 1 hour at 200°C a cyan-dye image density of at least 50 % versus the initial density before heating is measured;
in that after applying the said method of manufacturing the support remains optically transparent for at least 80 % at 570 nm, and
in that the isotropic or approximately isotropic support is dimensionally stable in that the shrinkage after heating is less than 5 %.
Method according to claim 1, wherein said oilformer is dibutylphthalate, tricresylphosphate or a mixture thereof.
Method according to claim 1 or 2, wherein after heat-treatment for 1 hour at 200°C a cyan-dye image density of more than 70% versus the initial density before heating is measured.
Method according to any of claims 1 to 3, wherein the support remains optically transparent for at least 90 % at 570 nm.
Method according to any of claims 1 to 4, wherein the said shrinkage is less than 1.5 %.
Method according to any of claims 1 to 5, wherein said isotropic or approximately isotropic support is characterised by a ratio of the elasticity modulus, measured in a perpendicular and in a parallel direction, of less than 1.3.
Method according to any of claims 1 to 6, wherein said support is a glass support or wherein said support comprises linear condensation polymers having a glass transition temperature above 190°C.
Method according to claim 7, wherein said support comprising linear condensation polymers is a polyethylene terephthalate, a polyethylene naphthalate or a polyether sulphon support.
Silver halide colour photographic print material comprising as a support an optically transparent and isotropic or approximately isotropic support which is characterised by a ratio of the elasticity modulus, measured in a perpendicular and in a parallel direction, of less than 1.3, said support being dimensionally stable in that the shrinkage after heat-treatment for 1 hour at 200°C is less than 5 %;
and a plurality of spectrally sensitive silver halide emulsion layers coated thereon, each of which are sensitive to a different region of the visible wavelength spectrum, wherein a red-sensitive emulsion layer comprises at least one cyan dye image forming coupler present as an oilformer dispersion, said cyan dye forming coupler corresponding to the general formula (I),
representing a 2,5-diacylaminophenol-type colour coupler, wherein:

Z represents a hydrogen atom or a coupling off group,

X is a ballasting group of sufficient size rendering said colour coupler non-diffusing in an alkali-permeable layer of a photographic element,

Rⁿ, represents H, an electron withdrawing atom or group, an aliphatic or aromatic substituent, or a linking group corresponding to the formula -Q-Rf, wherein Q is -O-, -S-, or -SO2-, and wherein Rf is a short-chain group, containing at least one electron-withdrawing group,

with the proviso that at least one of Rⁿ represents an electron-withdrawing atom or group or an aliphatic or aromatic substituent or linking group bound to a short-chain group carrying at least one electron withdrawing atom or group and wherein n represents an integer having a value from 1 to 5.
Material according to claim 9, wherein said support is a glass support or wherein said support comprises linear condensation polymers having a glass transition temperature above 190°C.