Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/20—Filters
  • G02B5/22—Absorbing filters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B47/00—Porphines; Azaporphines
  • C09B47/04—Phthalocyanines abbreviation: Pc
  • C09B47/06—Preparation from carboxylic acids or derivatives thereof, e.g. anhydrides, amides, mononitriles, phthalimide, o-cyanobenzamide
  • C09B47/067—Preparation from carboxylic acids or derivatives thereof, e.g. anhydrides, amides, mononitriles, phthalimide, o-cyanobenzamide from phthalodinitriles naphthalenedinitriles, aromatic dinitriles prepared in situ, hydrogenated phthalodinitrile
  • C09B47/0671—Preparation from carboxylic acids or derivatives thereof, e.g. anhydrides, amides, mononitriles, phthalimide, o-cyanobenzamide from phthalodinitriles naphthalenedinitriles, aromatic dinitriles prepared in situ, hydrogenated phthalodinitrile having halogen atoms linked directly to the Pc skeleton
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B47/00—Porphines; Azaporphines
  • C09B47/04—Phthalocyanines abbreviation: Pc
  • C09B47/06—Preparation from carboxylic acids or derivatives thereof, e.g. anhydrides, amides, mononitriles, phthalimide, o-cyanobenzamide
  • C09B47/067—Preparation from carboxylic acids or derivatives thereof, e.g. anhydrides, amides, mononitriles, phthalimide, o-cyanobenzamide from phthalodinitriles naphthalenedinitriles, aromatic dinitriles prepared in situ, hydrogenated phthalodinitrile
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B47/00—Porphines; Azaporphines
  • C09B47/04—Phthalocyanines abbreviation: Pc
  • C09B47/08—Preparation from other phthalocyanine compounds, e.g. cobaltphthalocyanineamine complex
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B47/00—Porphines; Azaporphines
  • C09B47/04—Phthalocyanines abbreviation: Pc
  • C09B47/08—Preparation from other phthalocyanine compounds, e.g. cobaltphthalocyanineamine complex
  • C09B47/085—Preparation from other phthalocyanine compounds, e.g. cobaltphthalocyanineamine complex substituting the central metal atom
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B47/00—Porphines; Azaporphines
  • C09B47/04—Phthalocyanines abbreviation: Pc
  • C09B47/08—Preparation from other phthalocyanine compounds, e.g. cobaltphthalocyanineamine complex
  • C09B47/10—Obtaining compounds having halogen atoms directly bound to the phthalocyanine skeleton
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B67/00—Influencing the physical, e.g. the dyeing or printing properties of dyestuffs without chemical reactions, e.g. by treating with solvents grinding or grinding assistants, coating of pigments or dyes; Process features in the making of dyestuff preparations; Dyestuff preparations of a special physical nature, e.g. tablets, films
  • C09B67/0033—Blends of pigments; Mixtured crystals; Solid solutions
  • C09B67/0034—Mixtures of two or more pigments or dyes of the same type
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B67/00—Influencing the physical, e.g. the dyeing or printing properties of dyestuffs without chemical reactions, e.g. by treating with solvents grinding or grinding assistants, coating of pigments or dyes; Process features in the making of dyestuff preparations; Dyestuff preparations of a special physical nature, e.g. tablets, films
  • C09B67/0033—Blends of pigments; Mixtured crystals; Solid solutions
  • C09B67/0034—Mixtures of two or more pigments or dyes of the same type
  • C09B67/0035—Mixtures of phthalocyanines
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B69/00—Dyes not provided for by a single group of this subclass
  • C09B69/008—Dyes containing a substituent, which contains a silicium atom
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/20—Filters
  • G02B5/201—Filters in the form of arrays
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/20—Filters
  • G02B5/22—Absorbing filters
  • G02B5/223—Absorbing filters containing organic substances, e.g. dyes, inks or pigments
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
  • H10K59/30—Devices specially adapted for multicolour light emission
  • H10K59/38—Devices specially adapted for multicolour light emission comprising colour filters or colour changing media [CCM]

Definitions

• the present invention relates to color filters for electronic displays.
• display devices have been developed where thin-film active elements (thin- film transistors, also referred to as TFTs) are formed on a glass substrate, with display elements (for example, organic light-emitting diode layers to produce light, or liquid-crystal layers to block light from a backlight) then being formed on top.
• TFTs thin-film active elements
• display elements for example, organic light-emitting diode layers to produce light, or liquid-crystal layers to block light from a backlight
• a problem with displays combining white-emitting devices with color filters is that the combination of emitter and color filters must provide a good color gamut for the reproduction of a wide range of colors.
• Color filters used in this way must have good spectroscopic characteristics, with sufficient transmittance with the predetermined visible light region and no unnecessary transmittance in other regions of the visible spectrum.
• LCD liquid crystal displays
• Yamashita further teaches a blue filter wherein the x value can range from 0.13 to 0.15 and the y value can only be as low as 0.08 and a green filter wherein the x value can range from 0.22 to 0.34 with a y value ranging from 0.56 to 0.65. Both of these fall short of the respective desired primary x,y values, which if achieved would result in purer blue and green colors, respectively.
• liquid crystal displays commonly available often use a backlight such as a cold-cathode fluorescent light (CCFL).
• CCFL cold-cathode fluorescent light
• CCFL sources it is a characteristic of CCFL sources commonly available that, while it provides white light consisting of a variety of wavelengths of the visible spectrum, the light is often more intense in a few narrow bands of the spectrum. These bands are generally centered in the red, the green, and the blue regions of the spectrum.
• the color filters needed with such light sources do not need to be especially narrow to provide a good color gamut.
• a red filter can permit a transmittance "tail" into parts of the green region of the spectrum, so long as the tail region does not include the major green emission peak, and still provide good color with such a light source.
• Organic light-emitting diodes provide another light source for displays.
• OLED displays Unlike LCDs, which have a single full-display light source, OLED displays only produce light at the pixels that are required to be bright at a given time. Therefore, it is possible for OLED devices to provide displays that have reduced power requirements under normal usage.
• CFA color filter array
• the broadband-emitting structure is common to all pixels, and the final color as perceived by the viewer is dictated by that pixel's corresponding color filter element. Therefore, a multicolor or RGB device can be produced without requiring any patterning of the emitting structure.
• Bridged aluminum phthalocyanines have been proposed as an improved cyan or blue-green pigment in green color filters, see US 20080112068.
• US 20020117080 discloses pigments consisting of mixtures of copper and aluminum phthalocyanines where the phthalocyanine groups have been randomly chlorinated or brominated.
• US 4,311,775 discloses bis-aluminum phthalocyanines that are bridged with one or more siloxane groups as useful pigments for electrographical and photoelectrographic process.
• US 5,817,805 discloses a synthetic method for the preparation of bis(phthalocyanylalumino)tetraphenyldisiloxanes, including those in which the phthalocyanine group can contain halo groups.
• US 5,773,181 discloses the preparation of mixtures of fluoro and alkyl substituted metal phthalocyanines where the metal can be aluminum or copper.
• US20040030125 discloses silyl phthalocyanines including bridged bis-species and where the phthalocyanine groups contain low molecular weight fluorinated polymeric moieties.
• Fluorinated non-metal phthalocyanines or unbridged metal phthalocyanines have also been disclosed in Jones et al, Inorg. Chem., VoI 8, 2018(1969); Keller et al, J. Fluorine Chem., U, 73(1975); Peisert et al, J. Appl. Physics, 93(12), 9683(2003); US 6,051,702; US 4,892,941; US 2,227,628 and WO2005033110.
• Methods for making fluorinated phthalonitriles, often used as a precursor to the phthalocyanine group include US 4,209,458 and WO 1987007267.
• a color filter to provide improved color rendition, particularly with a broadband-emitting electronic display device and a display containing the filter. Improved color rendition includes increased transmittance, improved luminance and related properties such as improved 1931 CIE x,y chromaticity coordinates and improved spectral curve shape.
• a color filter comprising a mixture of a fluorinated phthalocyanine pigment having a maximum absorbance between 600-700nm and at least one second pigment with a maximum absorbance less than 620nm.
• One desirable embodiment is a green color filter where the second pigment has its maximum absorption at a wavelength from 400 to 500nm.
• a green color filter comprising a fluorinated phthalocyanine pigment having its maximum absorption at a wavelength from 600 to 700nm filter layer wherein at least 85 volume % of the pigment particles have a particle size less than 2750nm and preferably where at least 80 volume % have a particle size of less than lOOnm.
• the green filter layer has a transmittance of 60% or more at a wavelength of 520nm, of no more than 10% at a wavelength of 590nm and of no more than 10% at a wavelength of 480nm.
• the green color filter should have chromaticity coordinates (x,y) in the 1931 CIE XYZ colorimetric system, calculated using CIE Standard Illuminant C, that satisfies the expressions 0.19 ⁇ x ⁇ 0.21 and 0.69 ⁇ y ⁇ 0.71 as well as a greater % luminance at the same chromaticity coordinates than a green color filter prepared in identical manner using the analogous non-fluorinated phthalocyanine pigment.
• ADVANTAGES It is an advantage of this invention that it can produce color displays with an improved combination of color and luminance relative to existing displays by utilizing highly concentrated dispersions of fluorinated phthalocyanines.
• Concentrated dispersions of fluorinated phthalocyanines can be prepared in organic solvents, which are easy to remove in the process of manufacturing color filters, and have small particle size and narrow particle size distribution which minimize scatter, leading to improved transmittance.
• this invention can provide greater luminance at the target NTSC chromaticity position and thus better overall rendition of colors while improving manufacturability and lowering cost.
• FIGs. Ia to Id show example pixel configurations that can be used for an electronic display using this invention.
• FIG. 2a shows a cross-sectional view of one embodiment of an electronic display that can be used with this invention.
• FIG. 2b shows another embodiment of an electronic display that can be used with this invention.
• FIG. 3 a shows the particle size distribution in terms of % of particles versus size for a fluorinated phthalocyanine of the invention.
• FIG. 3b shows the particle size distribution in terms of % of particles versus size for an analogous comparative non-fluorinated phthalocyanine.
• FIG. 4 shows the % transmittance versus wavelength for inventive and comparative green filters.
• electrostatic display refers to a display wherein electronic entities control the intensity of the different areas of the display.
• electronic entities can include e.g. an off-panel driver and a series of horizontal and vertical electrodes in a passive-matrix display, or an array of thin-film transistors (TFTs) in an active-matrix display.
• Such displays can include liquid crystal displays (LCDs) and organic light-emitting-diode (OLED) displays.
• LCDs liquid crystal displays
• OLED organic light-emitting-diode
• OLED display organic light-emitting display
• multicolor is employed to describe a display panel that is capable of emitting light of a different hue in different areas. In particular, it is employed to describe a display panel that is capable of displaying images of different colors. These areas are not necessarily contiguous.
• full color is commonly employed to describe multicolor display panels that are capable of emitting in at least the red, green, and blue regions of the visible spectrum and displaying images in any combination of hues.
• the complete set of colors that can be generated by a given display is commonly called the color gamut of the display.
• the red, green, and blue colors constitute the three primary colors from which all other colors can be generated by appropriate mixing. However, the use of additional colors that are within the color gamut of the device or additional colors to extend the color gamut of the device is possible.
• hue refers to the wavelength profile of light emission within the visible spectrum, with different hues exhibiting visually discernible differences in color.
• pixel is employed in its art-recognized usage to designate an area of a display panel that can be stimulated to emit light independently of other areas. It is recognized that in full-color systems, several pixels of different colors will be used together to generate a broad range of colors, and a viewer can term such a group a single pixel. For the purposes of this discussion, such a group will be considered several different colored pixels.
• maximum absorption and maximum transmittance refer to the maximum light absorption and maximum light transmittance, respectively, of color filters and color filter layers within the visible portion of the spectrum, i.e. from 400nm to 700nm.
• Red color filters are color filters that have a maximum transmittance substantially in the range of 600nm to 700nm.
• Green color filters are color filters that have a maximum transmittance substantially in the range of 500nm to 600nm.
• Blue color filters are color filters that have a maximum transmittance substantially in the range of 400nm to 500nm.
• FIG. 1 illustrates example pixel configurations that can be used for an electronic display using this invention.
• FIG. Ia shows a stripe pattern configuration of a device with group of pixels 20a.
• Group of pixels 20a includes red, green, and blue color-gamut-defining pixels 21a, 21b, and 21c.
• FIG. Ia is a common example of an RGB display.
• FIG. Ib shows a configuration of a device with group of pixels 20a including red, green, and blue color-gamut-defining pixels 21a, 21b, and 21c as well as extra pixel 21d, which can be a within-gamut pixel (e.g. white) or can be another color-gamut-defining pixel.
• One common arrangement utilizing FIG. Ib is an RGBW display, wherein portions of the display, e.g. within-gamut pixel 21d, would not have a color filter.
• FIG. Ic shows another pattern configuration of a device with group of pixels 20a.
• FIG. Id shows another pattern configuration of a device with group of pixels 20b.
• Other patterns can also be applied to the present invention, including patterns with more than 4 pixels. While in the above-mentioned examples, the pixels are shown to be arranged in a certain order, the pixels can be arranged in other embodiments having different orders, and other embodiments can have pixels with differing sizes and shapes.
• FIG. 2a there is shown a cross-sectional view of one embodiment of a bottom-emitting electronic display 10 that can be used with this invention.
• Electronic display 10 is an OLED device well known in the art.
• An organic electroluminescent (EL) element 70 comprising hole-injecting layer 35, hole-transporting layer 40, light-emitting layers 45 and 50, electron-transporting layer 55, and electron-injecting layer 60, is provided over an OLED substrate 80.
• Current is provided by cathode 90 and anodes 30a, 30b, and 30c.
• the display includes at least three separate filters, e.g. red color filter 25a, green color filter 25b, and blue color filter 25c, each of which is a separate emitting unit with its own anode 30a, 30b, and 30c, respectively.
• Color filters are often provided on a substrate.
• the substrate is also the device substrate 80.
• FIG. 2b there is shown another embodiment of an electronic display with color filters.
• Electronic display 15 is a top-emitting device.
• Color filters 25a, 25b, and 25c have been provided on a separate color filter substrate 85 that is placed over the electronic display after the electronic and emissive layers are provided. It will be understood that other arrangements of color filters commonly known in the art can be used with this invention. Further, other embodiments of electronic displays can be used, e.g. tandem OLED devices or liquid crystal displays.
• the process of preparing color filters from pigments commonly involves three steps: (a) a dispersing or milling step to break up the pigment to a dispersion of the primary particle; (b) a dilution or a mixing step in which the dispersed pigment concentrate is diluted with a carrier and other addenda, which can include other pigment dispersions, to a coating-strength pigment dispersion; and (c) coating a color filter layer from the coating-strength pigment dispersion onto a substrate.
• Step (a) can be further detailed as: (al) providing a pigment mixture containing a pigment and a carrier for the pigment, and optionally a dispersant; (a2) mixing the pigment mixture with milling media; (a3) introducing the mixture into a high-speed mill; (a4) milling the mixture to obtain a pigment dispersion wherein the pigment particles have the desired size; and (a5) separating the dispersion from the milling media.
• the pigment is usually suspended in a carrier (typically the same carrier as that in the coating-strength slurry) along with rigid, inert milling media.
• a carrier typically the same carrier as that in the coating-strength slurry
• Mechanical energy is supplied to this pigment dispersion, and the collisions between the milling media and the pigment cause the pigment to " deaggregate into its primary particles and fracture primary particles into smaller particles.
• a dispersant or stabilizer, or both, is commonly added to the pigment dispersion to facilitate dispersing smaller particles of the raw pigment, and to maintain colloidal particle stability, i.e. retarding particle reaggregation and settling.
• the grinding media can comprise particles, preferably substantially spherical in shape, e.g., beads, consisting essentially of a polymeric resin.
• the beads have sizes in the range of 10 to 100 microns, as described by Czekai et al.
• polymeric resins suitable for use as milling media are chemically and physically inert, substantially free of metals, solvent, and monomers, and of sufficient hardness and friability to enable them to avoid being chipped or crushed during milling.
• Suitable polymeric resins include crosslinked polystyrenes, such as polystyrene crosslinked with divinylbenzene, styrene copolymers, polyacrylates such as poly(methyl methylacrylate), polycarbonates, polyacetals, such as DerlinTM, vinyl chloride polymers and copolymers, polyurethanes, polyamides, poly(tetrafluoroethylenes), e.g., TeflonTM, and other fluoropolymers, high density polyethylenes, polypropylenes, cellulose ethers and esters such as cellulose acetate, poly(hydroxyethyl methacrylate), poly(hydroxyethyl acrylate), silicone containing polymers such as polysiloxanes and the like.
• the polymer can be biodegradable.
• biodegradable polymers include polylactides, polyglycolids, copolymers of lactides and glycolide, polyanhydrides, poly(imino carbonates), poly(N-acylhydroxyproline) esters, poly(N-palmitoyl hydroxyprolino) esters, ethylene-vinyl acetate copolymers, poly(orthoesters), poly(caprolactones), and poly(phosphazenes).
• the polymeric resin can have a density from 0.9 to 3.0 g/cm 3 . Higher density resins are especially useful inasmuch as these resins transfer more energy to provide more efficient particle size reduction. Especially useful are crosslinked or uncrosslinked polymeric media based on styrene.
• Milling can take place in any suitable grinding mill. Suitable mills include an airjet mill, a roller mill, a ball mill, an attritor mill, a vibratory mill, a planetary mill, a sand mill, and a bead mill.
• a high speed mill is particularly useful.
• high speed mill we mean milling devices capable of accelerating milling media to velocities greater than about 5 meters per second.
• the mill can contain a rotating shaft with one or more impellers. In such a mill the velocity imparted to the media is approximately equal to the peripheral velocity of the impeller, which is the product of the impeller revolutions per minute, ⁇ , and the impeller diameter.
• Sufficient milling media velocity is achieved, for example, in Cowles-type saw tooth impeller having a diameter of 40 mm when operated at 9,000 rpm.
• Useful proportions of the milling media, the pigment, the liquid dispersion medium and dispersant can vary within wide limits and depends, for example, upon the particular material selected and the size and density of the milling media.
• the process can be carried out in a continuous or batch mode.
• a slurry of ⁇ 100 ⁇ m polymeric resin milling media, liquid, pigment, and dispersant is prepared using simple mixing. This slurry can be milled in conventional high energy batch milling processes such as high speed attritor mills, vibratory mills or ball mills.
• This slurry is milled for a predetermined length of time to permit comminution of the active material to a minimum particle size.
• the dispersion of active material is separated from the milling media by a simple sieving or filtration with a barrier to the milling media but not the milled pigment, e.g. a filter with a pore size of 5 ⁇ m.
• a slurry of ⁇ 100 ⁇ m polymeric resin milling media, liquid, pigment, and dispersant can be continuously recirculated from a holding vessel through a conventional media mill which has a media separator screen adjusted to > 100 ⁇ m to permit free passage of the media throughout the circuit.
• the dispersion of active material is separated from the milling media by simple sieving or filtration.
• the contents of the milling mixture comprise the mill grind and the milling media.
• the mill grind comprises pigment, dispersant and a liquid carrier such as water or organic solvents.
• the pigment is usually present in the mill grind at 1 to 50 weight %, excluding the milling media.
• the weight ratio of pigment to dispersant is 20:1 to 1 :2.
• the high speed mill is a high agitation device, such as those manufactured by Morehouse-Cowles, Hockmeyer et al.
• the dispersant is another important ingredient in the mill grind.
• Useful dispersants include Solsperse 41000 (The Lubrizol Corporation) or other compositions sold under the Solsperse brand name, sulfates (e.g. sodium dodecyl sulfate), sulfonates (e.g. N-methyl-N-oleoyl taurate), acrylic and styrene-acrylic copolymers such as those disclosed in U.S. Pat. Nos. 5,085,698 and 5,172,133 (e.g. Joncryl 678), and sulfonated polyesters and styrenics such as those disclosed in U.S. Pat. No. 4,597,794.
• Disperbyk-111 BYK-Chemie GmbH, Germany
• Disperbyk-161 BYK- Chemie GmbH, Germany
• Other patents referred to above in connection with pigment availability also disclose a wide variety of useful dispersants.
• the milling time can vary widely and depends upon the pigment, mechanical structure, residence conditions, along with the initial and desired final particle size.
• milling times will typically range from 1 to 100 hours.
• the milled pigment concentrate is conveniently separated from the milling media by filtration.
• the carrier for the pigment can be an aqueous carrier medium or a non-aqueous solvent.
• aqueous carrier medium is water, an aqueous salt solution, or an aqueous solvent mixture comprising water and at least one water-miscible co-solvent. Selection of a suitable mixture depends on requirements of the specific application, such as desired surface tension and viscosity, the selected pigment, drying time of the color filter layer, and the type of material onto which the pigment dispersion will be coated.
• water-miscible co-solvents that can be selected include (1) alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, iso-butyl alcohol, furfuryl alcohol, and tetrahydrofurfuryl alcohol; (2) ketones or ketoalcohols such as acetone, methyl ethyl ketone, and diacetone alcohol; (3) ethers, such as tetrahydrofuran and dioxane; (4) esters, such as ethyl acetate, ethyl lactate, ethylene carbonate, and propylene carbonate; (5) polyhydric alcohols, such as ethylene glycol, diethylene glycol, Methylene glycol, propylene glycol, tetraethylene glycol, polyethylene glycol, glycerol, 2-methyl-2,4-pentanediol
• Useful non-aqueous solvents include ketones, hydrocarbons, alcohols, polyols, ethers, and esters. Of these, ketones and esters are preferred. Solvents known to be useful for this process include toluene, hexane, cyclohexanone, ethanol, butanol, glycol, and PGMEA (propylene glycol monomethyl ether acetate). A single solvent or mixtures of solvents may be used. A particularly suitable solvent mixture is cyclohexanone and PGMEA.
• the fluorinated phthalocyanine pigments of the invention are exceptionally useful with non-aqueous organic solvents, hi organic solvents, fluorinated phthalocyanine pigments readily mill to small particle sizes with a narrow particle size distribution.
• This treatment results in pigment particles wherein at least 85 volume % of the particles have a particle size less than 2750nm. It is very suitable that at least 80 volume % of the particles have a particle size less than lOOnm and particularly less than 68nm or even 36nm. However, this is not possible in all cases, and at a minimum, it is useful that at least 95 volume % of the pigment particles have a particle size less than 5000nm.
• Coating-Strength Dispersion Preparation In general it is desirable to make the pigment dispersion in the form of a concentrated mill grind, which is subsequently diluted to the appropriate concentration and further processed if necessary for use in coating. This technique permits preparation of a greater quantity of pigment slurry from the equipment. If the mill grind was made in a solvent, it can be diluted with water or optionally other solvents to the appropriate concentration. If it was made in water, it can be diluted with either additional water or water-miscible solvents to the desired concentration. If the color filter requires a mixture of pigments, it is useful at this point to mix pigment dispersions that have been milled separately.
• the pigment dispersion is adjusted to the desired viscosity, color, hue, saturation density, and area coverage for the particular application.
• the coating dispersion can contain up to approximately 30% pigment by weight, but will generally be in the range of approximately 0.1 to 20%, and conveniently approximately 5 to 15%, by weight of the total dispersion composition for most color filter coating applications. If an inorganic pigment is selected, the dispersion will tend to contain higher weight percentages of pigment than with comparable dispersions employing organic pigments, and can be as high as approximately 75% in some cases, since inorganic pigments generally have higher specific gravities than organic pigments.
• the amount of carrier medium is in the range of approximately 70 to 98 weight %, and conveniently approximately 80 to 95 weight %, based on the total weight of the dispersion.
• a mixture of water and a polyhydric alcohol, such as diethylene glycol is useful as the aqueous carrier medium, hi the case of a mixture of water and diethylene glycol, the carrier medium usually contains from about 30% water/70% diethylene glycol to about 95% water/5% diethylene glycol.
• Useful ratios are approximately 60% water/40% diethylene glycol to about 95% water/5% diethylene glycol. Percentages are based on the total weight of the carrier medium.
• the ability to coat a given surface can be affected by the surface tension of the coating-strength dispersion. Control of surface tensions is accomplished by additions of small amounts of surfactants.
• the level of surfactants to be used can be determined through simple trial and error experiments.
• Anionic, nonionic, and cationic surfactants can be selected from those disclosed in U.S. Pat. Nos. 5,324,349; 4,56,616 and 5,279,654 as well as many other surfactants.
• Commercial surfactants include the Surfynols® from Air Products; the Zonyls® from DuPont and the Fluorads® from 3M.
• a useful surfactant for these dispersions is Surfactant 1OG from Dixie Chemical.
• pigments are often coated onto a substrate.
• a color filter layer including the pigments can be coated onto any of a variety of rigid and non-rigid transparent or semi-transparent materials, such as glass or plastic.
• the substrate can be a substrate used solely for forming a color filter, which can be attached to a display device, hi another embodiment, the substrate can have other uses as well.
• a color filter layer or array of color filter layers can be coated onto the bottom of a bottom-emitting display device substrate.
• the pigments can be coated over the top of an emitting layer that forms part of a display device.
• the display device can be an electronic display, such as an LCD display or an OLED display.
• any of a variety of well-known coating and printing techniques can be used to prepare a color filter from the coating-strength pigment dispersion. These techniques can include, but are not limited to, extrusion-type hopper (X- hopper) coating, spin coating, spray coating, ultrasonic spray coating, knife coating, and gravure coating.
• the dispersion can be aqueous or non-aqueous, but preferably non-aqueous.
• the coated dispersion is then typically permitted to dry to form a solid or semi-solid coating.
• the slurry can include for example, gelling materials or crosslinking monomers to produce a solid or semisolid coating.
• the coating-strength pigment dispersion can include one or more photoresist compounds well-known in the art as useful for patterning color filters, e.g. in an array of colored pixels for an electronic display.
• processing of the coated dispersion can include patterned exposure and post- exposure processing to form a patterned color filter.
• the final color filter layers desirably comprise at least 10% color pigment, conveniently at least 25% color pigment, and usefully at least 50% color pigment by weight.
• One known class of pigments having good transmittance in the green region and a maximum absorption at a wavelength within the range of from 600 to 700nm is the metallophthalocyanines.
• commercially available metallophthalocyanine pigments such as pigment blue 15 (copper phthalocyanine) are well-known for their excellent lightfastness, they tend to be more blue than green in hue, and thus are less than optimal for use in a green color filter.
• Hydroxyaluminum phthalocyanine exhibits a greener hue than copper phthalocyanine, but suffers from relatively poor lightfastness.
• One class of pigments which display both excellent hue for the first pigment requirements and lightfastness are the so-called bridged aluminum phthalocyanines as described by Regan in U.S. Pat. No. 4,311,775, the contents of which are incorporated herein by reference.
• a particular example of a non-fluorinated siloxane-bridged aluminum phthalocyanine is bis(phthalocyanylalumino)tetraphenyldisiloxane.
• a fluorinated phthalocyanine of the invention is defined as one containing a phthalocyanine group that is substituted directly by either fluorine or by perfluorinated groups. It does not refer to phthalocyanine molecules with fluorine or fluorine containing groups elsewhere in the molecule. For example, a fluoride ion or a perfluoroctanoxide group coordinated to the metal atom of a metallized phthalocyanine would not be a fluorinated phthalocyanine of the invention.
• the fluorinated phthalocyanine pigments of the invention are cyan or blue-green in color; that is, they have a maximum absorbance in the region of 600- 700 nm.
• the fluorinated phthalocyanines according to the invention are according to Formula (I):
• M is a metal cation chosen from groups 2a, 3 a, lb-5b of the periodic table;
• R is fluorine, a perfluoroalkyl or a perfluoroaryl group; z is 1 to 4;
• L is an anionic ligand; and n is 0 or 1 such that the overall charge on the molecular unit is neutral.
• M is a metal cation chosen from Groups 2a, 3 a, lb-5b of the Periodic Table of the Elements so that the metal cation is at least divalent. The most suitable metal cations are Cu +2 and Al +3 . Of these, Al +3 is preferred.
• R represents a fluoro, a perfluoroalkyl or a perfluoroaryl substituent on each of the four phenyl groups in the phthalocyanine ring system.
• perfluoroalkyl groups include trifluoromethyl, -C 2 Fs and -C 8 F 17.
• a specific example of a perfluoroaryl group is pentafluorophenyl. Of these, fluoro and trifluoromethyl are preferred with fluoro being most preferred.
• z represents the number of fluorine containing substituents on the phthalocyanine group and can range from 1 to 4 per phenyl group.
• pigments derived from 3,5- difluorophthalonitrile may not be symmetrical and isomers may arise since each individual phenyl group of the four in the phthalocyanine group may be substituted in either the 3,5 or the 4,6 positions.
• all possible individual isomers and mixtures of isomers (in terms of fluorine location) in any combination are part of the invention.
• Suitable monoanionic L groups include halides such as fluoride, chloride, bromide, hydroxide, phenoxide and thiophenoxide. L can also represent a bridging ligand that connects two independent phthalocyanine units.
• Suitable dianionic L groups include -O-, - OCH 2 CH 2 O-, -0-Si(R) 2 -O-, -0-Si(R) 2 -O-Si(R) 2 -O-, -O-Si(R) 2 -R-Si(R) 2 -O-and - 0-P(R) 2 -O-P(R) 2 -O- where R is alkyl or aryl, particularly phenyl.
• L is a bridging ligand
• the phthalocyanine units can be the same or different. When the phthalocyanine units are different, it is not necessary that both phthalocyanine units are fluorinated.
• Preferred pigment types are those according to Formula (II):
• R is fluoro or trifluoromethyl and z is 1-4. Of this type, the most preferred structures are where z is 1 and when R is fluoro.
• Another preferred pigment type is those according to Formula (III):
• R is fluoro or trifluoromethyl
• z is 1-4 and X is a halide, hydroxide, -O- or -0-Si(R) 2 -O-Si(R) 2 -O- where the substituents on the Si atom are alkyl or aryl, particularly phenyl.
• X groups the bridging ligand -0-Si(R) 2 -O-Si(R) 2 -O- is highly preferred.
• inventive pigments include, but are not limited to, the following:
• fluorinated metal phthalocyanine can also be used in combination with other solid pigments during the milling step provided that the fluorinated metal phthalocycanine comprises at least 50 weight % of the mixture.
• Illustrative examples include other cyan or blue-green pigments, including non- fluorinated phthalocyanines such as copper phthalocyanine, or pigments with maximum absorbance of less than 620 nm such as Pigment Yellow 185.
• the fluorinated phthalocyanine comprises at least 80%, or even 95%, by weight of the mixture. Synthesis of a fluorinated phthalocvanine:
• Inv-1 can be synthesized by the following scheme:
• the collected solid was placed in a 25OmL erlenmyer flask, 50 mL of 5% aqueous NaOH was added and the mixture was stirred magnetically for 20 minutes rapidly.
• the insoluble material was collected on a Buchner funnel.
• the collected product was washed with 5OmL of acetone then 5OmL of ligroin, then dried on the Buchner funnel.
• the product was placed back in a 25OmL erlenmyer flask and 50 mL of 5% aqueous NH 4 OH was added.
• This solid is completely non-wetting, that is: the solid remains a completely dry powder on top of the colorless liquid and stirring does not wet the solid.
• the dry powder was collected on a Buchner funnel.
• the filtrate was totally colorless.
• the collected solid was washed with 5OmL of distilled water, 10OmL of acetone, then dried on the Buchner for 20 minutes. After transfer into a 25OmL erlenmyer flask 10OmL of acetone was added. The mixture was brought to boiling with stirring on a hot plate, held at boiling for 15 minutes, then filtered through Whatman #54 filter paper while hot. The filtrate is very light blue.
• the product was dried on the Buchner funnel for 15 minutes then dried in a vacuum oven at 60 deg.C overnight.
• the weight of collected intermediate chloroaluminum tetrafiuorophthalocyanine as a deep dark blue powder was 9.3 grams (14.3 mmoles, 95.9% yield).
• the flask was placed in an oil bath pre-heated to 130 deg.C.
• the reaction was stirred and heated at reflux overnight.
• the chloroaluminum tetrafluorophthalocyanine appeared to dissolve partially in hot pyridine.
• After stirring overnight the reaction remained deep blue and freely stirring.
• the flask was removed from the oil bath, cooled to approximately 100 deg.C and the insoluble product was collected on a Buchner funnel using Whatman #54 filter paper (filtered while hot).
• the collected blue product was washed with 4 x 5OmL pyridine until the washes were very light blue, then washed with 10OmL acetone, and 25mL ligroin P950.
• the product was dried on the Buchner for one hour then dried in a vacuum oven for one hour at 60 deg.C.
• the weight of deep blue product was 6.4 grams (3.9 mmoles, 94.3% of theory).
• Analysis by IR and MS showed small levels of starting material still in this isolated product.
• the crude product was then placed in a 25OmL erlenmyer flask and slurried with 125mL dimethylformamide at reflux for 40 minutes.
• the insoluble material was collected on a Buchner funnel usingWhatman #54 filter paper.
• the hot DMF slurry purification was repeated once.
• the color filter of the invention contains at least one second pigment with a maximum absorbance less than 620nm and is a different color from the fluorinated phthalocyanine. Since blue color filters should have maximum transmittance substantially in the range of 400nm to 500nm and the fluorinated phthalocyanine has low absorbance in the region of 500-600nm, a suitable second pigment for a blue color filter should have a maximum absorbance in the region of 500-620nm, preferably between 520-580nm. An example of a useful second pigment for use in a blue color filter is Pigment Violet 23.
• a useful green color filter according to this invention has good light transmittance in the green region of the spectrum (500 to 600nm) and good light absorption in the red and blue regions of the spectrum.
• One useful embodiment of this green color filter has a fluorinated phthalocyanine pigment having good transmittance in the green region and a maximum absorption at a wavelength within the range of from 600 to 700nm, and a second pigment having good transmittance in the green region and a maximum absorption at a wavelength within the range from 400 to 500nm.
• Fluorinated phthalocyanine pigments still have significant transmittance in the blue region.
• they are desirably combined with a second pigment having a maximum absorption at a wavelength within the range from 400 to 500nm.
• pigments that which is commercially known as the monoazo yellow pigment classes, or more simply monoazo pigments.
• Useful yellow pigments include Pigment Yellow 138, Pigment Yellow 139, Pigment Yellow 180, Pigment Yellow 74, Pigment Yellow 185, Pigment Yellow 154 and mixtures thereof are preferred. Especially preferred are Pigment Yellow 185 and Pigment Yellow 74. Pigment numbers are as designated in the Color Index.
• useful ratios of the first pigment to the second pigment have been found to be in the range of 40:60 to 75:25 by weight.
• a color filter layer prepared from such dispersions can have good transmittance in the green region of the visible spectrum while having good absorption in other regions of the spectrum.
• the green filter layer so prepared can have a maximum transmittance of 60% or more at a wavelength of 520nm, but of no more than 10% at a wavelength of 590nm and of no more than 10% at a wavelength of 480nm.
• the width at half-height of such a filter layer can be 80nm or less.
• the width at half-height is defined as the width of the transmittance peak at one-half of the maximum transmittance.
• Such a filter layer has chromaticity coordinates (x,y) in the 1931 CIE XYZ colorimetric system, when calculated using CIE Standard Illuminant D65 or Standard Illuminant C, that satisfy the expressions 00.19 ⁇ x ⁇ 0.21 and 0.69 ⁇ y ⁇ 0.71. This is a very pure green color.
• Example 1 To a 1 L stainless steel cold water jacketed vessel with a specially designed baffle, 244 g of a 1 :1 (w/w) solvent mixture comprised of propylene glycol monomethyl ether acetate (PGMEA) and cyclohexanone was introduced along with 11.25 g of dispersant polymer Solsperse 41000. Then, a 50 mm diameter tool steel D blade connected to a vertical Caframo mechanical stirrer was submerged into the solvent. While operating the stirrer at 500 rpm, 45 g of Inv-1 was added followed by 600 g of 0.2 mm Zirstar (zirconium silicate milling media).
• PGMEA propylene glycol monomethyl ether acetate
• Dispersant polymer Solsperse 41000 cyclohexanone
• the resulting dispersion was milled by gradually increasing the mixing rate starting with 18 h @ 1600 rpm, then ramping to 2800 rpm over 6 h, holding at 2800 rpm for 18 h and finishing with 5 h @ 3000 rpm.
• the dispersion was isolated after separation from the milling media by pressure filtration through a 20 micron filter.
• the particle distribution of the dispersed pigment was confirmed by using a dynamic light scattering sizing technique (Figure 3a).
• Example 2 The experiment was executed as outlined in Example 1 with the following exceptions; Inv-1 was replaced with the analogous non- fluorinated reference material bis(phthalocyanylalumino)tetraphenyldisiloxane and the starting 1600 rpm mixing rate was extended to 22 h. while omitting the 6 h ramp step before 18 h mixing @ 2800 rpm and the final 5 h @ 3000 rpm.
• the particle distribution is shown in Figure 3b.
• a comparison of the particle size distribution in terms of cumulative volume % below a certain size for Examples 1 and 2 are shown in
• Example 3 (yellow dispersion used to make green filters): The solvent PGMEA (545 g) was combined with dispersant polymer Disperbyk 161 (31.5 g solution w/ 4.5% active polymer) in a 2.0 L stainless steel cold water jacketed vessel with no baffle. A 70mm diameter high-shear Cowles disperser blade connected to a Ross mechanical stirrer (Model HSM-100H2) was submerged and the stirrer set to 500 rpm. While in operation, 50.4 g of Pigment Yellow 185 was introduced followed by 700 g of 50-micron milling media composed of crosslinked polystyrene divinyl benzene.
• the dispersion was milled by gradually increasing the mixing rate; 1.5 h @ 1000 rpm, 16 h @ 1100 rpm, and 3 h @ 1200 rpm.
• the dispersion was isolated from the milling media by pressure filtration through a 5 micron filter.
• a baffled vessel is used, the pigment to polymer ratio is 1 :0.5 and the milling time is reduced to 2 h.
• Inventive Green Filter A sample of the fluorinated phthalocyanine nanodispersion from Example 1 was transferred into a glass bottle. Then, the Pigment Yellow 185 dispersion from Example 3 was added to obtain a pigment ratio of 0.95 to 1.0 respectively. The bottle was sealed with a cap and the contents manually shaken until the dispersions were completely mixed.
• a thin-film of the green dispersion was spin-coated onto the surface of a glass plate previously cleaned using standard glass cleaning techniques.
• the spin-coating parameters were set to achieve film thicknesses between 1.5 and 2.0 microns. Spectral and thickness measurements were taken towards the center of the glass plate.
• Comparative Green Filters 1 and 2 the cyan dispersion prepared in Example 2 was combined in a bottle with the Pigment Yellow 185 dispersion from Example 3 to achieve a pigment ratio of 1.24 to 1.0 respectively. The bottle was sealed with a cap and the contents manually shaken until the dispersions were completely mixed. A thin-film of the green dispersion was spin-coated onto the surface of a glass plate previously cleaned using standard glass cleaning techniques. The spin-coating parameters were set to achieve film thicknesses between 1.5 and 2.0 microns. Total spectral transmittance and thickness measurements were taken towards the center of the glass plate (Comparative Green Filter 1).
• Comparative Green Filter 2 For Comparative Green Filter 2, the same coating from Comparative Filter 1 was used, however, total spectral transmittance and thickness measurements were taken towards the edge of the glass plate.
• FIG 4 shows the % transmittance versus wavelength for these inventive and comparative green filters and is tabulated in Tables 2 and 3.
• Comparative Filter 2 Data collected for Comparative Filter 2 demonstrates that a thinner filter improves the % Transmittance to a position closer to the Inventive Filter, which is 11.1% higher in peak transmittance than Comparative Filter 1 , but its bandwidth at half peak transmittance is broader by about 4nm on the bathochromic side. This increase in breadth is undesirable because it leads to a less favorable chromaticity position as described in Table 4 below.
• the aim is to achieve the x,y chromaticity coordinates of the NTSC green primary when the green filters are cascaded with CIE Standard Illuminant C and the 1931 CIE color matching functions.
• Table 4 shows the resulting chromaticity coordinates after cascading the Inventive and both Comparative Filters with CIE Standard Illuminant C and the 1931 CIE color matching functions.
• the resulting CIE chromaticity coordinates for the Inventive Filter are essentially equal to those of the target NTSC green primary and very similar to those for Comparative Filter 1.
• the x,y delta values show that the chromaticity coordinates of the thinner Comparative Filter 2 are farther away from those of the target NTSC green primary and Comparative Filter 1.
• thinning Comparative Filter 1 to get a percent transmittance closer to that of the Inventive Filter compromised the chromaticity coordinate position away from the target NTSC green primary position.
• the percent transmittance advantage of the Inventive Filter over Comparative Filter 1 translates directly into a luminance advantage of about 15% at essentially the same chromaticity position.
• the luminance advantage of 15% holds true for white light sources other than CIE Standard Illuminant C.
• CIE Standard Illuminant D65, a broadband-emitting OLED display device, or a CCFL for an LCD are all light sources that when cascaded with the Inventive Filter give a 15% luminance advantage over Comparative Filter 1 at roughly equal chromaticity.
• Comparative Filter 2 which results from a thinner film coating of the Comparative Filter 1 formulation, can produce a 20% luminance advantage over Comparative Filter 1 when cascaded with CIE Standard Illuminant C.

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