MODIFIED POLY(MALEIC ANHYDRIDE-CO-STYRENE) AND RELATED POLYMERS AS A BASE FOR COLOR FILTERS

Abstract: A method of producing color elements, for use in color filter arrays and the like, and a material for use in such methods, is disclosed. The material may be a modified poly(maleic anhydride-co-styrene) and related polymers. The polymers may be used as vehicles in a clear or partially clear form, as protective or blocking and anti-leach/stain coatings. The polymers may also be combined with dyes to produce the respective color elements. The materials are compatible with conventional photolithographic methods.

Description: MODIFIED POLY(MALEIC ANHYDRIDE-CO-STYRENE) AND RELATED POLYMERS AS A BASE FOR COLOR FILTERS Technical Field This invention relates generally to polymeric materials for use in information display devices and sensors where the coatings contain an organic colorant to selectively pass (or reject) a band of frequencies in the ultra-violet (uv) , visible, or infrared (ir) portion of the electromagnetic spectrum, and to optically transparent barrier coatings providing leach/stain resistance. Background Art Production of color flat-panel displays and color video detectors relies on the use of colored polymeric coatings (referred to hereafter as color filters) to construct an array of colored pixels, usually red, green, and blue for flat-panel displays and cyan, magenta, and yellow for color video detectors. In flat-panel displays the color filters are arranged in a pattern on a transparent substrate to allow selective passage of light from a light source positioned behind the color filter array. Color video detectors use color filter arrays to pass ambient light of predetermined wavelengths to an addressed array of semiconductor photo-cells positioned behind the color filter array. Color filter plate and color video detector production relies on the use of photolithographic processes to define the array of colored pixels. Two conventional general methods employed in patterning the pixel arrays are wet-etch (solvent etching) and dry-etch (plasma or reactive ion etching) . Both methods require the color filter to be applied uniformly over the substrate to form a film, typically 1 - 2 μm thick for color filters. Application of the color filter is generally effected by a process known as spin-coating whereby the color filter solution is placed in the center of the spinning substrate and spread uniformly over the surface by centrifugal forces. Wet-etch processing is a multi-step process typically involving 1) application of the color filter, 2) soft bake to partially insolubilize the coating, 3) application of photoresist, 4) exposure of photoresist, 5) solvent removal of exposed photoresist and underlying color filter, 6) solvent removal of remaining photoresist, 7) final cure of color filter. These steps are repeated for each additional color filter employed where subsequent color filters are applied over the previously processed color filters and patterned by selective removal as previously described. Dry-etch processing is a multi-step process typically involving, 1) application of the color filter, 2) hard bake to cure the polymer, 3) application of photoresist, 4) solvent removal of exposed photoresist, 5) removal of remaining photoresist and areas of color filter that are not coated with photoresist using a reactive plasma. The manufacture of a multi-colored array necessitates coating each additional color filter on top of the previously processed color filters. When a color filter solution is coated over a previously processed color filter a phenomenon referred to as leaching can occur in which the dyes in the previously processed color filter diffuse out of the polymer matrix into the solvent of the subsequent layer being applied. Another phenomenon referred to as staining can also take place in which the dyes in the color filter solution being applied can diffuse into the previously processed color filter. Both phenomena result in intermixing of the dyes which can decrease the chromaticity of the color filters. Applicant is aware of U.S. Patents: U.S. Pat. No. 4,822,718, U.S. Pat. No. 4,876,165, and "Color Filters From Dyed Polyimides", W. Latham and D. Hawley, Solid State Technology. May 1988, the disclosures of which are incorporated by reference herein. The effects of leaching and staining have been reduced by using a polyimide precursor (polyamic acid) as the color filter matrix material(e.g. , as described in U.S.4,876,165 and U.S. 4,822,718). The use of dyed polyimides as color filters is also described by W. Latham and D. Hawley in "Color Filters From Dyed Polyimides", Solid State Technology. May 1988. In accordance with Latham and Hawley, dyed polyimides cured at 230° C for one hour offer substantial resistance to leaching and staining for film thicknesses of 1 to 2 μm. However, the leach and stain resistance of dyed polyimides is dependant on the dye loading, i.e. the ratio of dye to polymer, the specific dye, the cure time/temperature, and the structure of the polyimide. Polyimides used in color filters require care to manufacture consistently. As known, of the major factors affecting the manufacture of polyimides include monomer purity, order of monomer addition, rate of monomer addition, reaction temperature, stir speed and time, and ambient humidity. As known, color filter formulations using polyimides require careful formulation/evaluation processes to produce a product that performs within established specifications. Polyimides used in color filters also lose some of their optical clarity when heated at temperatures high enough to effect adequate cure. This loss of optical clarity is evidenced by a yellow coloration of the cured film which is believed to be due to the formation of charge transfer complexes. Polyimide based color filters also have a limited shelf-life. Polyimide precursors (polyamic acids) undergo a continuous association/dissociation of the amide linkage which results in variation of molecular weight with time. These variations in molecular weight can result in variations of the film thickness when coated at a given spin-speed and may require process adjustment, as known. Disclosure of the Invention It is therefore an object of the present invention to provide a composition capable of forming a transparent polymeric film capable of resisting staining from subsequent application of a dyed coating. It is a further object of the present invention to provide a composition containing an organic dye capable of resisting leaching of the dye when the coating comes into contact with solvents in subsequent processing steps. It is a further object of the present invention to provide a composition that has a longer useful shelf-life than the prior art, thereby allowing manufacture of a final product that maintains processibility within designated specifications for a longer period of time. It is an object of this invention to provide a coating that does not leach. It is yet another object of the present invention to provide a composition that does not stain. It is still another object of the present invention to provide a photosensitive coating for use in information display devices and sensors. It is an object of the present invention to provide an optically transparent barrier coating. Another object of the present invention is to provide a color filter base, for both positive and negative photolithographic processes, that has good electrical properties, including resistivity and dielectric strength. An object of the present invention is to provide a brightener/color contrast transmitting film having a higher degree of clarity on all colors than the prior art. For example, the transmitting film makes a blue which is brighter than the blue of the prior art. It is yet another object of the present invention to provide a composition that can be manufactured with consistent properties. It is still another object of the present invention to provide a composition having a longer shelf life than conventional materials. It is a further object of the present invention to provide a one component system. It is an object of the present invention to provide a compound that can be securely adhered to glass and other substrates. These and other objects are met by the present invention through combining a modified copolymer containing pendant anhydride groups and a material containing two or more reactive functional groups, capable of reacting with a carboxylic acid, into a single chemical entity, and thereby providing a polymeric coating with good solvent resistance, transparency, and thermal stability. In accordance with the present invention, coatings consisting of copolymers containing pendant anhydride groups that have been grafted with a reactive crosslinking component and blended with a polyfunctional crosslinking component (preferably a blocked polyisocyanate) , capable of reacting with a carboxylic acid, have been found to exhibit good transparency, thermal stability, solvent resistance, leach resistance, and stain resistance. A more complete understanding of the invention will be apparent to those skilled in the art by reference to the Drawings and Description of the Preferred Embodiments incorporated herein. Brief Description of the Drawings FIG. 1 is a chart demonstrating the leach resistance of color filter elements incorporating the invention; FIG. 2 is a chart demonstrating the leach resistance of an alternative color set incorporating the invention; FIG. 3 is a flow chart showing preparation of test color wheels incorporating the invention; FIG. 4 is a chart showing staining of conventional coatings of the prior art; FIG. 5 is a chart showing the protective effect of clear coatings incorporating the invention; FIG. 6 is a flow chart showing preparation and use of a clear coating according to the invention; FIG. 7 is a chart showing the protective effect of using a clear photosensitive coating according to one embodiment of the invention; FIG. 8 is a chart showing the staining and leach resistance of coatings protected by a clear coating according to the invention; FIG. 9 is a chart showing the leach resistance provided by a clear photosensitive coating according to one embodiment of the invention; FIG. 10 is a chart similar to FIG. 9 using a thinner protective coating; FIG. 11 is a flow chart showing a conventional color system according to the prior art; and FIG. 12 is a flow chart showing preparation of a color system according to the invention. Best Mode for Carrying Out the Invention In accordance with the present invention, transparent polymeric coating materials with leach and stain resistance can be prepared by reacting certain copolymers which contain pendant anhydride groups, such as poly(maleic anhydride-co-styrene) ,e.g. , available under the trade name "SMA® Resins" from Atochem Inc. and under the tradename "Scripset® Resins" from Monsanto Company, and also available from Aldrich and Monomer-Polymer Dajac Labs, poly(maleic anhydride-co-methylvinyl ether) , e.g., available under the tradename "Gantrez® AN Copolymer" from ISP Technologies, or poly(maleic anhydride-co-ethylene) , e.g., available from Zeeland Chemicals Inc. , preferably poly(maleic anhydride-co-styrene) . with a polyfunctional component having one functional group capable of reaction with the anhydride and one or more functional groups that are capable of thermal, photo, or chemically induced polymerization. The polyfunctional component (referred to hereafter as a reactive graft component) is preferably allylamine, diallyla ine, 3-amino-l-propanol vinyl ether, allyl alcohol, 4-hydroxybutyl vinyl ether, glycerol dimethacrylate, 2-hydroxyethyl methacrylate, or 2-hydroxyethyl acrylate. The stoichiometry of the reactive graft component with respect to the pendant anhydrides may range from 0.5 to 1.0, preferably 1.0. Reaction of the pendant anhydrides with the reactive graft component results in cleavage of the anhydride and subsequent formation of a carboxylic acid(C=0 stretch, 1706-1760 cm "1 )and a carboxylic acid ester(C=0 stretch, 1715-1770 cm "1 ), if the functional group of the reactive graft component that reacts with the anhydride is a hydroxyl group, or an amide(C=0 stretch, 1630-1700 cm "1 ) , if the functional group of the reactive graft component that reacts with the anhydride is an amino group. Let it be noted that the infra-red C * =0 stretching frequencies stated above represent typical absorption frequencies for the chemical functionalities described above, as reported in "Spectrometric Identification Of Organic Compounds", Silverstein, Robert M. ; Bassler, G. Clayton; Morrill, Terence C. , Fourth Edition, Wiley, N.Y. The above stated infra-red absorption frequencies may be used as an indication of reaction when grafting the reactive graft component onto the anhydride-containing copolymer. The carboxylic acid formed as a result of reacting a hydroxyl-containing compound or an amino-containing compound with the anhydride functional group of the copolymer renders the grafted copolymers readily soluble in dilute aqueous base. The increased rate of dissolution in dilute aqueous base compared to the dissolution rate of the ungrafted copolymer provides a qualitative indication of successful graft. A more quantitative measure of degree of graft is obtained by determination of acid number by titration with a base. The grafted copolymer is then blended with a crosslinking component that is capable of reacting with the pendant carboxylic acid groups, or unreacted anhydride groups, of the grafted copolymer. The crosslinking component can be a melamine based curative, e.g, such as is available under the tradename Cymel® from Cytec Industries Inc., or polyfunctional isocyanates. The crosslinking component is preferably a blocked diisocyanate or more preferably, a blocked polyisocyanate. Blocked polyisocyanates of this type are available, e.g., under the tradename "Desmodur" from Miles Inc. and under the tradename "Luxate" from Olin Chemicals. The use of blocked isocyanates permits preparation of a one part formulation with extended shelf-life since the blocked isocyanates are unreactive until heated to a predetermined temperature. Heating the blocked isocyanate to its deblock temperature generates a "free" isocyanate capable of reactions typically associated with isocyanates. During the thermal curing process the blocked isocyanate groups begin to deblock to form free isocyanate groups at temperatures ranging from 60° C to 200° C depending on the type of blocking agent used. The free isocyanates generated in this manner then react with the carboxylic acid groups of the grafted copolymer to form an amide as described in "Organic Polymer Chemistry", K.J. Saunders, Chapman and Hall, New York, 1973. There is also the possibility of secondary reactions of the isocyanates with other functional groups containing a labile proton, such as amides, as well as reactions with other isocyanate groups. The reactions of the deblocked isocyanates described above produce extensive crosslinking of the polymer matrix. When the reactive graft component is an unsaturated alkyl group, it is also believed that at temperatures above 200°C the unsaturated bonds of the pendant reactive graft components react to provide additional crosslinking. The reactive graft component can also contain a photo-crosslinkable functionality, such as an acrylate radical. The structure of the starting maleic anhydride copolymer can be described, generally as follows: Where R = H, The structure of the grafted maleic anhydride copolymer can be described, generally as follows: (A) (B) Where X can be a linear or branched unsaturated alcohol or amine containing from about 2 to 20 carbon atoms. Mixtures of linear or branched unsaturated alcohols and/or amines may also be employed. m can be from 0.2 to 1 and n can be from 0.8 to 0. The moiety on the right (B) is maleic anhydride copolymer, as peviously described, and the moiety on the left (A) is the grafted component which may contain the amine or alcohol components, as previously described. The substituent groups added to the reactive sites on the anhydride may include groups of greater complexity and functionality, for example, as follows: Where X can be an oxygen atom or a nitrogen atom. R^ is a linear or branched divalent alkylene of from about 1 to 6 carbon atoms or an oxyalkylated derivative thereof. R2 is a vinyl, acrylate, or methacrylate radical, m can be from 0.2 to 1 and n can be from 0.8 to 0. The applicants' grafted copolymer/blocked polyisocyanate blend can be applied directly to provide an optically transparent, thermally stable, chemical resistant and leach/stain resistant barrier coating with uniform coating thickness. The applicants' grafted copolymer/blocked polyisocyanate blend may also be combined with colorants to provide a uniform colored film coating possessing leach/stain resistance for use as a color filter for information displays and detectors. Depending upon the method and the application, the applicants polymeric coating (with or without colorants) may be several microns to a few hundred Angstroms in thickness. Conventional spin-coating usually yields a film from about 0.1 μm to ten microns in thickness depending on molecular weight of the grafted copolymer and the speed at which the coating is spin-coated. Typical speeds for spin-coating the applicants polymeric coating (with or without colorants) may vary from 500 rpm to 6000 rpm depending on the type and size of substrate to be coated and the molecular weight of the copolymer and crosslinking agent used, as well as the composition of the coating. Films of greater thickness may be achieved with higher polymer solids levels and/or higher molecular weight polymer, as well as by use of other coating methods. Typical cure cycles for the applicants' polymeric coating range from 200°C to 280°C for times of 10 minutes to 60 minutes. Some specific applications for applicants' polymeric coating include binder for dyes or pigments to form color filter arrays for use in liquid crystal displays, electro-luminescent displays, plasma displays and imaging systems such as charge-coupled devices for color video detectors. Applicants' polymeric coating may also be applied over coatings that lack sufficient leach/stain resistance to serve as a barrier coating to prevent staining and leaching of the aforementioned coating. Applicants' polymeric coating may also be used as an interlayer dielectric in multi-layer microcircuit fabrication. Applicants' polymeric coating may also be used in the construction of optical wave-guides. EXAMPLE 1 Into a reaction vessel equipped with an agitator, a nitrogen inlet tube and a calcium chloride drying tube, there is charged 800 parts of N-methyl-2-pyrrolidinone and 49.8 parts allylamine. After purging the reactor with nitrogen for several minutes, 250.56 parts of styrene-maleic anhydride copolymer having a number average molecular weight of about 350,000 (Aldrich 18,293-1) and an acid number of 473 are added in a single charge while stirring. An additional 100 parts of N-methyl-2-pyrrolidinone are used to rinse the inside walls of the reactor. Stirring is continued for about 48 hours. The infra-red spectrum of the polymer shows a reduction in the intensity of the anhydride absorptions at 1858 cm "1 and 1780 cm "1 and new absorption bands at 1732 cm "1 and 1646 cm "1 corresponding to the C=0 stretching vibrations of a carboxylic acid and a secondary amide, respectively. The product had an acid number of 157. EXAMPLE 2 Into a reaction vessel equipped with an agitator, a nitrogen inlet tube and a calcium chloride drying tube, there is charged 202.23 parts of styrene-maleic anhydride copolymer having a number average molecular weight of about 350,000 (Aldrich 18,293-1) and an acid number of 473 and 500 parts of N-methyl-2-pyrrolidinone. After purging the reactor with nitrogen for several minutes, the reactor is heated with an electric heating mantel to a temperature 25°C to 75°C while stirring. After all solids are dissolved, the solution is allowed to cool to about 35°C. To the stirring solution there is added dropwise a solution consisting of 48.50 parts allylamine in 152.78 parts N-methyl-2-pyrrolidinone. Stirring is continued at room temperature for about 48 hours. The product had an acid number of 159. EXAMPLE 3 Into a reaction vessel equipped with an agitator, a nitrogen inlet tube and a calcium chloride drying tube, there is charged 100 parts of N-methyl-2-pyrrolidinone. After purging the reactor with nitrogen for several minutes, there is added 46.71 parts of styrene-maleic anhydride copolymer having a number average molecular weight of about 1600 - 2600 and an acid number of 475 (Monomer-Polymer & Dajac Labs, catalog # 9182) . An additional 20 parts of N-methyl-2-pyrrolidinone are used to rinse the inside walls of the reactor. To the stirring solution there is added dropwise a solution consisting of 13.19 parts allyla ine in 20 parts N-methyl-2-pyrrolidinone. Stirring is continued at room temperature for about 24 hours. The product had an acid number of 144. EXAMPLE 4 Into a reaction vessel equipped with an agitator, a nitrogen inlet tube and a calcium chloride drying tube, there is charged 50 parts of N-methy1-2-pyrrolidinone, 50 parts of diethylene glycol dimethyl ether, and 5.87 parts allylamine. After purging the reactor with nitrogen for several minutes, 30 parts of styrene-maleic anhydride copolymer having a number average molecular weight of about 350,000 (Aldrich 18,293-1) and an acid number of 473 are added to the stirring solution. A mixture 21.74 parts of N-methyl-2-pyrrolidinone and 21.74 parts diethylene glycol dimethyl ether is used to rinse the inside walls of the reactor. Stirring is continued for about 48 hours. The product had an acid number of 172. EXAMPLE 5 Into a reaction vessel equipped with an agitator, a nitrogen inlet tube and a calcium chloride drying tube, there is charged 40.44 parts of styrene-maleic anhydride copolymer having a number average molecular weight of about 350,000 (Aldrich 18,293-1) and an acid number of 473 and 100 N-methy1-2-pyrrolidinone. After purging the reactor with nitrogen for several minutes, a solution consisting of 8.60 parts allyl alcohol and 23.56 parts N-methyl-2-pyrrolidinone is added followed by addition of a solution of 15.00 parts triethylamine and 23.56 parts N-methyl-2-pyrrolidinone while stirring. The reaction is heated to 50°C - 65°C with an electric heating mantel. Stirring is continued for about 48 hours. The product had an acid number of 148. EXAMPLE 6 Using the following coating formulation: 30.00 parts polymer blend consisting of 150 parts allylamine grafted styrene-maleic anhydride copolymer solution as described in Example 1, 51 parts blocked polyisocyanate (Des odur BL-3175A, Miles Inc.), 10 parts N-methyl-2-pyrrolidinone and 25 parts eye1ohexanone. 26.55 parts N-methyl pyrrolidinone 10.86 parts cyclohexanone 7.22 parts Solvent Blue 45 2.40 parts Solvent Blue 67 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a blue coating was prepared by stirring the mix for about 12 hours. The mix was then filtered to remove ion exchange resin and undissolved material. The coating may be used as a color filter in a multicolor pixel array for use in full-color flat-panel displays to selectively pass predominantly blue light from a light source behind the panel. The coating may also be used as a color filter in a multicolor pixel array to selectively pass predominantly blue light to a semiconductor photodetector array. The coating may be applied by conventional spin or spray techniques on a substrate and cured at 230°C for 60 minutes or 250°C for 30 minutes. The coating may be patterned by conventional plasma etch techniques. EXAMPLE 7 U Ussing the following coating formulation: 30.00 parts polymer blend as described in Example 6 26.55 parts N-methyl pyrrolidinone 10.86 parts cyclohexanone 5.61 parts Solvent Blue 38 4.03 parts Solvent Yellow 82 1100 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a green coating was prepared, as described in Example 6. EXAMPLE 8 Using the following coating formulation: 30.00 parts polymer blend as described in Example 6 26.55 parts N-methyl pyrrolidinone 10.86 parts cyclohexanone 4.50 parts Solvent Yellow 82 5.13 parts Solvent Red 119 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) Company) a red coating was prepared, as described in Example 6. EXAMPLE 9 Using the following coating formulation: 30.00 parts polymer blend consisting of 150 parts allylamine grafted styrene-maleic anhydride copolymer as described in Example 1, 75 parts blocked polyisocyanate (Des odur BL-4165, Miles Inc.), 10 parts N-methyl-2-pyrrolidinone, and 25 parts cyclohexanone. 28.42 parts N-methyl pyrrolidinone 11.30 parts cyclohexanone 7.47 parts Solvent Blue 45 2.49 parts Solvent Blue 67 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a blue coating was prepared, as described in Example 6. EXAMPLE 10 Using the following coating formulation: 30.00 parts polymer blend as described in Example 9 28.42 parts N-methyl pyrrolidinone 11.30 parts cyclohexanone 5.80 parts Solvent Blue 38 4.16 parts Solvent Yellow 82 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a green coating was prepared, as described in Example 6. EXAMPLE 11 Using the following coating formulation: 30.00 parts polymer blend as described in Example 9 28.42 parts N-methyl pyrrolidinone 11.30 parts cyclohexanone 4.65 parts Solvent Yellow 82 5.31 parts Solvent Red 119 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a red coating was prepared, as described in Example 6. EXAMPLE 12 Using the following coating formulation: 20.00 parts polymer blend consisting of 100 parts allylamine grafted styrene-maleic anhydride copolymer solution as described in Example 1, 18.5 parts blocked polyisocyanate(Des odur BL-3175A, Miles Inc.), 28.68 parts N-methyl-2-pyrrolidinone, and 51.84 cyclohexanone. 22.06 parts N-methyl pyrrolidinone 11.03 parts cyclohexanone 3.36 parts Solvent Blue 38 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a cyan coating was prepared, as described in Example 6. EXAMPLE 13 Using the following coating formulation: 20.00 parts polymer blend as described in Example 12 17.78 parts N-methyl pyrrolidinone 8.89 parts cyclohexanone 2.40 parts Solvent Red 127 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a magenta coating was prepared, as described in Example 6. EXAMPLE 14 Using the following coating formulation: 20.00 parts polymer blend as described in Example 12 24.89 parts N-methyl pyrrolidinone 12.44 parts cyclohexanone 4.00 parts Solvent Yellow 82 10 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) a yellow coating was prepared, as described in Example 6. EXAMPLE 15 Using the following coating formulation: 5.00 parts polymer blend consisting of 20.00 parts allyl alcohol grafted styrene-maleic anhydride copolymer solution as described in Example 5, 5.41 parts blocked polyisocyanate(Desmodur BL-3175A, Miles Inc.), 15.36 parts N-methyl pyrrolidinone, and 10.00 parts diethylene glycol dimethyl ether 1.00 parts N-methyl pyrrolidinone 1.38 parts diethylene glycol dimethyl ether 4.92 parts dye stock consisting of 56.25 parts Solvent Blue 45, 18.75 parts Solvent Blue 67, 112.5 parts N-methyl pyrrolidinone, and 112.5 parts diethylene glycol dimethyl ether stirred over 64 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) for 12 - 24 hours followed by filtration to remove ion exchange resin and undissolved materials, a blue coating was prepared, as described in Example 6. EXAMPLE 16 Using the following coating formulation: 5.00 parts polymer blend as described in Example 15 1.00 parts N-methyl pyrrolidinone 1.38 parts diethylene glycol dimethyl ether 4.92 parts dye stock consisting of 43.65 parts Solvent Blue 38, 31.35 parts Solvent Yellow 82, 112.5 parts N-methyl-pyrrolidinone, and 112.5 parts diethylene glycol dimethyl ether stirred over 64 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) for 12 - 24 hours followed by filtration to remove undissolved materials. a green coating was prepared, as described in Example 6. EXAMPLE 17 Using the following coating formulation: 5.00 parts polymer blend as described in Example 15 1.00 parts N-methyl pyrrolidinone 1.38 parts diethylene glycol dimethyl ether 4.92 parts dye stock consisting of 35.03 parts Solvent Yellow 82, 39.97 parts Solvent Red 119, 130 parts N-methyl-pyrrolidinone, and 130 parts diethylene glycol dimethyl ether stirred over 64 parts Dowex® HCR-S-H ion exchange resin (Dow Chemical Company) for 12 - 24 hours followed by filtration to remove undissolved materials. a red coating was prepared, as described in Example 6. EXAMPLE 18 Using the following formulation: 5.50 parts grafted copolymer as described in Example 1 1.93 parts blocked polyisocyanate (Desmodur BL-3175A, Miles Inc.) 1.19 parts Solvent Blue 67 1.64 parts Solvent Brown 44 11.31 parts cyclohexanone 4.13 parts N-methyl-2-pyrrolidinone 10 parts Dowex HCR-S-H ion exchange resin a black coating was prepared, as described in Example 6. EXAMPLE 19 Using the following formulation: 6.37 parts grafted copolymer as described in Example 1 2.17 parts blocked polyisocyanate (Desmodur BL-3175A, Miles Inc.) 3.56 parts cyclohexanone 3.42 parts N-methyl-2-pyrrolidinone a clear coating was prepared by stirring the mix for about 1 hour. The mix was then filtered through a 0.2 μm filter. The coating may be used as a transparent barrier layer over color filters to provide protection against leaching of the dyes from the color filter and to protect against staining of the color filter during subsequent processing steps. It will be appreciated that various dyes may be added to produce a coating which is transparent at selected wavelengths and opaque at other wavelengths. For example, the coating may be transparent at the spectra used to determine alignment, but opaque, or colored, at other wavelengths. EXAMPLE 20 The blue color filter formulation described in Example 6 was spin-coated onto a three inch diameter glass substrate at 1000 rpm for 90 seconds, baked on a hotplate at 100°C for 30 - 60 seconds, pre-baked in a convection oven at 170°C for 30 minutes, and hard-baked (cured) in a convection oven at 250°C for 30 minutes. Film thickness was 1.45 μm. The transmittance spectrum of the cured color filter film is represented by line a in Figure 1. The coated glass substrate was then immersed in N-methyl-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line b in Figure 1. The coated glass substrate was immersed a second time in N-methy1-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line c in Figure 1. EXAMPLE 21 The green color filter formulation described in Example 7 was spin-coated onto a three inch diameter glass substrate at 1000 rpm for 90 seconds, baked on a hotplate at 100°C for 30 - 60 seconds, pre-baked in a convection oven at 170°C for 30 minutes, and hard-baked (cured) in a convection oven at 250°C for 30 minutes. Film thickness was 1.24 μm. The transmittance spectrum of the cured color filter film is represented by line d in Figure 1. The coated glass substrate was then immersed in N-methy1-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line e in Figure 1. The coated glass substrate was immersed a second time in N-methy1-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line f in Figure 1. EXAMPLE 22 The red color filter formulation described in Example 8 was spin-coated onto a three inch diameter glass substrate at 1000 rpm for 90 seconds, baked on a hotplate at 100°C for 30 - 60 seconds, pre-baked in a convection oven at 170°C for 30 minutes, and hard-baked (cured) in a convection oven at 250°C for 30 minutes. Film thickness was 1.36 μm. The transmittance spectrum of the cured color filter film is represented by line g in Figure 1. The coated glass substrate was then immersed in N-methyl-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line h in Figure 1. The coated glass substrate was immersed a second time in N-methyl-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry •28- nitrogen. The transmittance spectrum was recorded again and is represented by line i in Figure 1. EXAMPLE 23 The cyan color filter formulation described in Example 12 was spin-coated onto a three inch diameter glass substrate at 2000 rpm for 90 seconds, baked on a hotplate at 100°C for 30 - 60 seconds, and hard-baked (cured) in a convection oven at 250°C for 30 minutes. Film thickness was 0.579 μm. The transmittance spectrum of the cured color filter film is represented by line a in Figure 2. The coated glass substrate was then immersed in N-methyl-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line b in Figure 2. The coated glass substrate was immersed a second time in N-methy1-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line c in Figure 2. EXAMPLE 24 The yellow color filter formulation described in Example 14 was spin-coated onto a three inch diameter glass substrate at 2000 rpm for 90 seconds, baked on a hotplate at 100°C for 30 - 60 seconds, and hard-baked (cured) in a convection oven at 250 Q C for 30 minutes. Film thickness was 0.585 μm. The transmittance spectrum of the cured color filter film is represented by line d in Figure 2. The coated glass substrate was then immersed in N-methyl-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line e in Figure 2. The coated glass substrate was immersed a second time in N-methyl-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line f in Figure 2. EXAMPLE 25 The magenta color filter formulation described in Example 13 was spin-coated onto a three inch diameter glass substrate at 2000 rpm for 90 seconds, baked on a hotplate at 100°C for 30 - 60 seconds, and hard-baked (cured) in a convection oven at 250°C for 30 minutes. Film thickness was 0.708 μm. The transmittance spectrum of the cured color filter film is represented by line g in Figure 2. The coated glass substrate was then immersed in N-methy1-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line h in Figure 2. The coated glass substrate was immersed a second time in N-methyl-2-pyrrolidinone for 30 seconds after which it was dried under a stream of dry nitrogen. The transmittance spectrum was recorded again and is represented by line i in Figure 2. EXAMPLE 26 Using the following formulation: 6.37 parts grafted copolymer as described in Example 1 2.17 parts blocked polyisocyanate (Desmodur BL-3175A, Miles Inc.) 3.56 parts cyclohexanone 3.42 parts N-methyl-2-pyrrolidinone a clear coating was prepared by stirring the mix for about 1 hour. The mix was then filtered through a 0.2 μm filter. The coating may be used as a transparent barrier layer over color filters to provide protection against leaching of the dyes from the color filter and to protect against staining of the color filter during subsequent processing steps. EXAMPLE 27 Evaluation of the stain resistance of the formulation of Example 25 was conducted by preparing a three-color color wheel on a three inch diameter glass substrate, as illustrated in Figure 3, that simulates the processing steps used in preparing a color filter plate. The steps used in preparing the color wheel are as follows: 1) Spin-coat clear barrier coat of example 25 at 1220 rpm for 90 seconds, bake on hotplate at 100°C for 30 - 60 seconds, bake in convection oven at 250°C for 60 minutes. Film thickness was 1.1 μm. Spectra of clear coat after this step is shown in Figure 4, line a. 2) Spin-coat red color filter (Brewer Science, Inc. PiC* Red 101) at 1200 rpm for 90 seconds, bake on hotplate at 100°C for 30 - 60 seconds, bake in convection oven at 164°C for 30 minutes. 3) Spin-coat positive working photoresist (Shipley Microposit* 1400-27) at 5000 rpm for 30 seconds, hotplate bake at 100°C for 30 seconds. 4) The sample was then exposed to actinic light (150 mJ/cm 2 ) from a contact printer through a wedge-shaped mask placed over the coated substrate. 5) The sample was immersed in 0.27 N tetramethylammoniu hydroxide (TMAH) for 20 seconds followed by rinsing in deionized water to remove exposed resist and underlying Red 101 leaving a hemi-circular pattern of Red 101. The unexposed resist remaining on top of the Red 101 was removed with SafeStrip* (Brewer Science, Inc.). The remaining Red 101 was then hard-baked (cured) in a convection oven at 280°C for 10 minutes. Red 101 film thickness was approximately 1.25 μm per certificate of analysis. Spectra of the Red 101 and the clear coat after this step are shown in Figure 4, lines b and c, respectively. 6) Spin-coat green color filter (Brewer Science, Inc. PiC* Green 02) at 1200 rpm for 90 seconds, bake on hotplate at 100°C for 30 - 60 seconds, bake in convection oven at 170°C for 30 minutes. Spin-coat positive working photoresist (Shipley Microposit* 1400-27) at 5000 rpm for 30 seconds, hotplate bake at 100°C for 30 seconds. The sample was then exposed to actinic light (150 mJ/cm 2 ) from a contact printer through a wedge-shaped mask placed over the coated substrate and rotated 90 degrees from its position in step 4. 7) The sample is immersed in 0.27 N tetramethylammonium hydroxide (TMAH) for 20 seconds followed by rinsing in deionized water to remove exposed resist and underlying Green 02 leaving a hemi-circular pattern of Green 02. The unexposed resist remaining on top of the Green 02 is removed with SafeStrip* (Brewer Science, Inc.). The remaining Green 02 is then hard-baked (cured) in a convection oven at 230°C for 60 minutes. Green 02 film thickness was approximately 1.20 μm per certificate of analysis. Spectra of the Green 02, Red 101, and the clear coat after this step are shown in Figure 4, lines d, e, and f, respectively. 8) Spin-coat blue color filter (Brewer Science, Inc. PiC* EXP93004) at 1000 rpm for 90 seconds, bake on hotplate at 100°C for 30 - 60 seconds, bake in convection oven at 155°C for 30 minutes. Spin-coat positive working photoresist (Shipley Microposit* 1400-27) at 5000 rpm for 30 seconds, hotplate bake at 100°C for 30 seconds. The sample is then exposed to actinic light (150 mJ/cm 2 ) from a contact printer through a wedge-shaped mask placed over the coated substrate and rotated 90 degrees from its position in step 6. 9) The sample is immersed in 0.27 N tetramethylammonium hydroxide (TMAH) for 20 seconds followed by rinsing in deionized water to remove exposed resist and underlying EXP93004 leaving a hemi-circular pattern of EXP93004. The unexposed resist remaining on top of the EXP93004 is removed with SafeStrip*(Brewer Science, Inc.). The remaining EXP93004 is then hard-baked (cured) in a convection oven at 230°C for 60 minutes. EXP93004 film thickness was approximately 1.00 μm per certificate of analysis. Spectra of the EXP93004, Green 02, Red 101, and the clear coat after this step are shown in Figure 4, lines g, h, i, and j, respectively. In Figure 4, the slight decrease in transmittance of the clear coat, represented by lines a, c, f, and j, is a result of thermal darkening. There is no spectral evidence of staining from any of the subsequent color filter processing steps. Line g in Figure 4 shows a decrease in transmittance of the red color filter due to staining from subsequent processing of the blue color filter. A second color wheel was prepared as described above in steps 1 - 9 with the exception that a second application of the clear coat in Example 25 was applied after processing the red color filter as described in step 5. The second application of clear coat was spin-coated at 6000 rpm for 90 seconds, baked on hotplate at 100°C for 30 - 60 seconds, and baked in convection oven at 250°C for 60 minutes. The transmittance spectrum of the clear coat and each color filter was recorded after each hard-bake as described in steps 1 - 9 for the first color wheel. Lines a - j in Figure 5 correspond to the same processing steps as lines a - j in Figure 4. Line g in Figure 5 indicates no staining of the red color filter by the subsequent application of the blue color filter. The slight decrease in the transmittance of the red color filter represented by line g in Figure 5 is due to thermal degradation of the dyes. EXAM LE 28 Into a reaction vessel equipped with an agitator, and a calcium chloride drying tube, there is charged 50.00 parts of SafeStrip* (Brewer Science, Inc.) to which is added 40.00 parts styrene-maleic anhydride copolymer having a number average molecular weight of about 1900 (Atochem SMA3000A) and an acid number of 290. After all solids are dissolved, there is added 12.00 parts 2-hydroxyethyl acrylate (HEA) (RohmTech AM-414) and 10 drops of triethylamine (Aldrich 23,962-3). Stirring is continued at room temperature for about 24 hours. EXAMPLE 29 Into a 100 mL polyethylene beaker there is charged 29.82 parts of the grafted polymer prepared in Example 27, 5.00 parts dipentaerythritol penta-/hexa- acrylate (Aldrich 40,728-3, and 8.69 parts SafeStrip* (Brewer Science, Inc.). The mix is stirred at room temperature for 1 hour and stored in an amber polyethylene screw-cap bottle for 14 days. EXAMPLE 30 An optical transparent negative working photoresist is prepared by combining 10.00 parts of the formulation prepared in Example 28, 1.90 parts blocked polyisocyanate (Desmodur B1-3175A, Miles Inc), 20.00 parts SafeStrip*, 1.00 parts isopropylthioxanthone (ITX) (First Chemical Corp.), 0.50 parts octyl-para-(dimethylamino) benzoate(ODAB) (First Chemical Corp.), and 0.025 parts 1,4-diazabicyclo[2.2.2]octane (Aldrich D2,780-2). The mix is stirred for 1 hour at room temperature and filtered through a 0.2 μm. EXAMPLE 31 Evaluation of the formulation of Example 29 was conducted by preparing a three-color color wheel on a three inch diameter glass substrate, as illustrated in Figure 6, that simulates the processing steps used in preparing a color filter plate. The steps used in preparing the color wheel are as follows: l) Spin-coat red color filter (Brewer Science, Inc. PiC* Red 02) at 1000 rpm for 90 seconds, bake on hotplate at 100 β C for 30 seconds, bake in convection oven at 151°C for 30 minutes. 2) Spin-coat transparent negative working photoresist prepared in Example 29 at 4000 rpm for 90 seconds, hotplate bake at 100°C for 3 minutes. 3) The sample was then exposed to actinic light (150 mJ/cm 2 ) from a contact printer through a wedge-shaped mask placed over the coated substrate followed by baking on a hotplate at 100°C for 2 minutes. 4) The sample was immersed in 0.27 N tetramethylammonium hydroxide (TMAH) for 20 seconds followed by rinsing in deionized water to remove unexposed resist and underlying Red 02 leaving a hemi-circular pattern of Red 02 with a layer of transparent resist on top. The remaining Red 02 and transparent resist were then hard-baked (cured) in a convection oven at 230°C for 30 minutes. Red 02 film thickness was approximately 1.2 μm per certificate of analysis. Transparent resist film thickness was approximately 0.35 μm. Spectrum of the Red 02 coated with the transparent resist after this step are represented by line a in Figure 7. 5) Spin-coat green color filter (Brewer Science, Inc. PiC* Green 02) at 1100 rpm for 90 seconds, bake on hotplate at 100 β C for 30 seconds, bake in convection oven at 165°C for 30 minutes. Spin-coat transparent negative working photoresist prepared in Example 29 at 4000 rpm for 90 seconds, hotplate bake at 100°C for 3 minutes. The sample was then exposed to actinic light (150 mJ/cm 2 ) from a contact printer through a wedge-shaped mask placed over the coated substrate and rotated 90 degrees from its position in step 3. 6) The sample was immersed in 0.27 N tetramethylammonium hydroxide (TMAH) for 20 seconds followed by rinsing in deionized water to remove unexposed resist and underlying Green 02 leaving a hemi-circular pattern of Green 02. The remaining Green 02 and transparent resist were then hard-baked (cured) in a convection oven at 230°C for 30 minutes. Green 02 film thickness was approximately 1.20 μm per certificate of analysis. Transparent resist film thickness was approximately 0.35 μm. Spectra of the Green 02 coated with transparent resist and Red 02 coated with the transparent resist after this step are represented by lines b and c, respectively, in Figure 7. 7) Spin-coat blue color filter (Brewer Science, Inc. PiC* Blue 10) at 1200 rpm for 90 seconds, bake on hotplate at 100°C for 30 seconds, bake in convection oven at 160°C for 30 minutes. Spin-coat transparent negative working photoresist prepared in Example 29 at 4000 rpm for 90 seconds, hotplate bake at 100°C for 3 minutes. The sample was then exposed to actinic light (150 mJ/cm 2 ) from a contact printer through a wedge-shaped mask placed over the coated substrate and rotated 90 degrees from its position in step 5. 8) The sample was immersed in 0.27 N tetramethylammonium hydroxide (TMAH) for 20 seconds followed by rinsing in deionized water to remove unexposed resist and underlying Blue 10 leaving a hemi-circular pattern of Blue 10. The remaining Blue 10 and transparent resist were then hard-baked (cured) in a convection oven at 230°C for 30 minutes. Green 02 film thickness was approximately 1.20 μm per certificate of analysis. Transparent resist film thickness was approximately 0.35 μm. Spectra of the Blue 10 coated with transparent resist. Green 02 coated with transparent resist, and Red 02 coated with the transparent resist after this step are represented by lines d, e, and f, respectively, in Figure 7. In Figure 7, the slight decrease in transmittance of the Red 02, represented by lines a, c, and f, and of the Green 02, represented by lines b and e, is a result of thermal darkening and some staining from any of the subsequent color filter processing steps, but the effect is minimal. A second color wheel was prepared as described above in steps 1 - 9 with the exception that the Blue 10 was not hard-baked after development in TMAH. Instead, the color wheel was placed on the spinner and spun at 2000 rpm while being sprayed with a stream of N-methyl-2-pyrrolidinone from a scrueeze bottle for approximately 10 seconds. The color wheel was allowed to spin at 2000 rpm for an additional 80 seconds to aid in drying the wheel. Figure 8 shows the spectrum of the Red 02 and Green 02 after each hard-bake and removal of Blue 10 where lines a, c, and e represent the transmittance spectra of Red 02 and lines b and d represent the transmittance spectra of Green 02. The spectra show slight decreases in transmittance for the Red 02 and the Green 02 due to thermal decomposition of the dyes. The spectra indicate that the removal of the Blue 10 with N-methyl-2-pyrrolidinone did not stain the Green 02 and Red 02 and that there was no leaching of dyes from the Green 02 and Red 02 during the Blue 10 removal step. EXAMPLE 32 Three glass substrates, measuring three inches in diameter, were coated with a blue color filter material (EXP94056, Brewer Science, Inc.) by spin-coating at 800 rpm for 90 seconds. Each sample was baked on a hotplate for 30 seconds. Sample 1 was baked in a convection oven at 250 β C for 30 minutes, sample 2 was baked in a convection oven at 230°C for 60 minutes, and sample 3 was baked in a convection oven at 165°C for 30 minutes. Sample 2 was spin-coated with a 1:1 dilution of the transparent resist, described in Example 29, and SafeStrip* (Brewer Science, Inc.). The diluted transparent resist was spin-coated at 1000 rpm for 90 seconds, followed by a hotplate bake at 100°C for 3 minutes. The sample was flood-exposed (150 mJ/cm 2 ) on a contact printer and placed in a convection oven at 230°C for 30 minutes. Film thickness was determined to be 0.39 μm from a spin-curve. Sample 3 was coated with the diluted transparent resist, as previously described, by spin-coating at 5000 rpm for 90 seconds, followed by a hotplate bake at 100°C for 3 minutes. The sample was flood-exposed (150 mJ/cm 2 ) on a contact printer and placed in a convection oven at 230°C for 30 minutes. Film thickness was determined to be 0.1 μm from a spin-curve. Evaluation of solvent resistance was performed by immersing each sample in N-methy1-2-pyrrolidinone. The spectrum of each sample was recorded before and after immersion in N-methyl-2-pyrrolidinone. Sample 1 was stripped from the substrate during immersion in N-methyl-2-pyrrolidinone. Line a in Figure 9 represents the transmittance spectrum of the blue color filter of sample 2 before application of the transparent resist. Line b in Figure 9 represents the transmittance spectrum of sample 2 with the transparent resist baked on. Line c in Figure 9 represents the transmittance spectrum of sample 2 with the transparent resist baked on, after immersion in N-methyl-2-pyrrolidinone for 30 seconds. Line a in Figure 10 represents the transmittance spectrum of the blue color filter of sample 3 after application and curing of the transparent resist. Line b in Figure 10 represents the transmittance spectrum of sample 3 with the transparent resist baked on, after immersion in N-methyl-2-pyrrolidinone for 30 seconds. While the above examples have been shown as using a separate vehicle and soluble dye, it will be appreciated that the dye may be a part of the vehicle polymer, e.g. attached to the polymer as an addition compound. The polymer may also be one which has the desired filtering properties, transmitting light of a desired wavelength, and excluding other wavelengths. It will be appreciated by those skilled in the art that variations in the invention disclosed herein may be made without departing from the spirit of the invention disclosed. The invention is not to be limited by the specific embodiments disclosed herein but only by the scope of the claims appended hereto:

Claims: Clai s 1. In a process of making color filter elements by photolithography, the improvement comprising, applying a layer of a substantially non-particulate filter coating material to a filter substrate, the filter coating material including a vehicle and a soluble dye incorporated therewith, the soluble dye being heat stable and in combination with the vehicle being effective to produce a high color contrast and brightness at reduced levels of back light, applying a photoresist to the layer of the filter coating material on the filter substrate, photographically imaging and developing the photoresist to form a pattern in the photoresist, transferring the pattern to the filter coating material by etching the patterned photoresist, to form a color filter element pattern in the color filter material, curing the color filter element to substantially insolubilize the color element, the cured filter element containing the stable dye being effective to consistently transmit and resolve colored light at high brightness, the cured filter element containing the stable dye having a high resistance to leaching and staining from adjacent application of subsequent filters. 2. The method of claim 1 wherein the substrate is coated with a substantially planar array of filter elements, the filter elements being of a plurality of colors. 3. The process of claim 2 including orienting the filter coating material in the color filter element to provide alignment. 4. The method of claim 3 including applying a liquid crystal material to the oriented filter coating material. 5. The method of claim 1 wherein the vehicle includes an anhydride modified copolymer grafted with a reactive crosslinking component and blended with a polyfunctional crosslinking component. 6. In a process of making microelectronic filter elements by microphotolithography, the improvement comprising applying a layer of a substantially non-particulate filter coating to a filter substrate, the filter coating material including a vehicle and a soluble dye incorporated therewith, the soluble dye being heat stable and in combination with the vehicle being effective to produce a high color contrast and brightness at reduced levels of back light, forming a pattern on the color filter material, and etching to form a color filter element, curing the color filter element to substantially insolubilize the color element, applying a barrier coating to the colored filter element, curing the barrier coating to substantially insolubilize the barrier coating, the cured filter element containing the stable dye being effective to consistently transmit and resolve colored light at high brightness, the cured barrier coating providing a high resistance to leaching and staining from adjacent application of subsequent filters. 7. In a process of making microelectronic filter elements by microphotolithography, the improvement comprising applying a layer of a substantially non-particulate filter coating material to a filter substrate, the filter coating material including a vehicle and a soluble dye incorporated therein, the soluble dye being heat stable and in combination with the vehicle being effective to produce a high color contrast and brightness at reduced levels of back light, applying a photosensitive barrier coating to the layer of color filter coating material on the filter substrate, photographically patterning the photosensitive barrier coating and developing the pattern in the barrier coating, transferring the pattern to the filter coating material by etching to form a color filter element covered by the patterned barrier coating, curing the color filter element and barrier coating to substantially insolubilize the color filter element and barrier coating, the cured color filter element containing the stable dye being effective to consistently transmit and resolve colored light at high brightness, the cured barrier coating providing a high resistance to leaching and staining from adjacent application of subsequent color filter elements. 8. A light absorbing coating material for photolithography including a vehicle and a soluble light absorbing dye incorporated therewith, the soluble dye being heat stable and in combination with the vehicle being effective to produce a high color contrast and brightness at reduced levels of back light, the vehicle including an anhydride modified copolymer grafted with a reactive crosslinking component and blended with a polyfunctional crosslinking component. 9. A color filter substrate having a patterned filter element thereon, the filter element including a substantially non-particulate filter coating material, the filter coating material including a vehicle and a dye incorporated therewith, the soluble dye being heat stable and in combination with the vehicle being effective to produce a high color contrast and brightness at reduced levels of back light, the filter element having a high resistance of leaching and staining from adjacent filters. 10. The filter substrate of claim 9 wherein the vehicle includes an anhydride modified copolymer grafted with a reactive crosslinking component and blended with a polyfunctional crosslinking component.

Inventors: PFEIFFER MICHAEL J, PFEIFFER, MICHAEL, J.
Applicants: BREWER SCIENCE INC, BREWER SCIENCE, INC.
Application year: 1996
Main classification: G03F9
IPC codes: G02B5, G03F7