WO1999060073A1 - Process and materials for inducing alignment of liquid crystals and liquid crystal optical elements - Google Patents
Process and materials for inducing alignment of liquid crystals and liquid crystal optical elements Download PDFInfo
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- WO1999060073A1 WO1999060073A1 PCT/US1999/010752 US9910752W WO9960073A1 WO 1999060073 A1 WO1999060073 A1 WO 1999060073A1 US 9910752 W US9910752 W US 9910752W WO 9960073 A1 WO9960073 A1 WO 9960073A1
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- liquid crystal
- alignment layer
- optical alignment
- dianhydride
- tetracarboxylic dianhydride
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- 0 C*(C(*1(C(*2c3ccc(C)c(*)c3)=O)C2=O)=O)C1=O Chemical compound C*(C(*1(C(*2c3ccc(C)c(*)c3)=O)C2=O)=O)C1=O 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1039—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors comprising halogen-containing substituents
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1085—Polyimides with diamino moieties or tetracarboxylic segments containing heterocyclic moieties
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
- G02F1/133711—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
- G02F1/133723—Polyimide, polyamide-imide
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
- G02F1/133742—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers for homeotropic alignment
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
- G02F1/13378—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation
- G02F1/133788—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation by light irradiation, e.g. linearly polarised light photo-polymerisation
Definitions
- the present invention relates to processes for aligning liquid crystals, and liquid crystal optical elements.
- Current liquid crystal display elements include a product that utilize a twisted nematic mode, i.e. having a structure wherein the aligning direction of nematic liquid crystal molecules is twisted by 90° between a pair of upper and lower electrode substrates, a product utilizing a supertwisted nematic mode, utilizing a birefringent effect, i.e.
- nematic liquid crystal molecules having a structure wherein the aligning direction of nematic liquid crystal molecules is twisted by 180° to 300°, an in-plane-switching mode wherein both electrodes controlling the liquid crystal alignment are present on one substrate and the direction of the liquid crystal orientation in the plane of the substrate changes upon application of an electric field, and a product utilizing a ferroelectric liquid crystal substance or an antiferroelectric liquid crystal substance.
- a liquid crystal layer disposed between a pair of substrates coated with a polymeric alignment layer.
- the polymeric alignment layer controls the direction of alignment of the liquid crystal medium in the absence of an electric field.
- the direction of alignment of the liquid crystal medium is established in a mechanical buffing process wherein the polymer layer is buffed with a cloth or other fiberous material.
- the liquid crystal medium contacting the buffed surface typically aligns parallel to the mechanical buffing direction.
- an alignment layer comprising anisotropically absorbing molecules can be exposed to polarized light to align a liquid crystal medium as disclosed in U.S. Pat. 5,032,009 and 4,974,941 "Process of Aligning and Realigning Liquid Crystal Media" which are hereby incorporated by reference.
- the process for aligning liquid crystal media with polarized light can be a noncontact method of alignment which has the potential to reduce dust and static charge buildup on alignment layers.
- Other advantages of the optical alignment process include high resolution control of alignment direction and high quality of alignment.
- Requirements of optical alignment layers for liquid crystal displays include low energy threshold for alignment, transparency to visible light (no color), good dielectric properties and voltage holding ratios, long-term thermal and optical stability and in many applications a controlled uniform pre-tilt angle.
- Most liquid crystal devices, including displays have a finite pre-tilt angle, controlled, for instance, by the mechanical buffing of selected polymeric alignment layers.
- the liquid crystal molecules in contact with such a layer aligns parallel to the buffing direction, but is not exactly parallel to the substrate.
- the liquid crystal molecules are slightly tilted from the substrate, for instance by about 2 - 15 degrees. For optimum performance in most display applications a finite and uniform pre-tilt angle of the liquid crystal is desirable.
- the present invention provides a process for inducing alignment of a liquid crystal medium adjacent to a surface of an optical alignment layer comprising: (a) exposing at least one optical alignment layer to polarized light; the polarized light having a wavelength within the absorption band of said optical alignment layer; wherein the exposed alignment layer induces alignment of the liquid crystal medium at an angle + and - ⁇ with respect to the direction of the polarization of the incident light beam and along the surface of the optical alignment layer; and
- the reaction product of at least one tetracarboxylic dianhydride and a diamine component comprising the reaction product of at least one tetracarboxylic dianhydride and a diamine component, wherein the diamine component comprises a 2-substituted 1 ,4- benzenediamine wherein the 2-substituent X, is an electron withdrawing group having a positive ⁇ , and M is a tetravalent organic radical derived from said tetracarboxylic dianhydride containing at least two carbon atoms, no more than two carbonyl groups of the dianhydride being attached to any one carbon atom of the tetravalent radical.
- the present invention also provides a composition for inducing alignment of a liquid crystal medium adjacent to a surface of an optical alignment layer comprising a polyamic acid of structure II
- X is -CN
- X 2 is independently selected from the group H, Cl, F, Br, R, and R,O-, wherein R, is independently selected from C, - C 3 perfluorinated alkyl chain, C, - C 3 partially fluorinated alkyl chain and C, - C 8 hydrocarbon chain
- m is 1 or 0
- Z is selected from the group -S-, -O-.
- Another embodiment of the invention is a polyimide derived from the polyamic acid and a liquid crystal display element made from the polyimide.
- FIG. 1 is a cross-sectional view of a general liquid crystal display element of the present invention.
- Fig. 2 shows a system which can be used to expose optical alignment layers to ultraviolet light.
- alignment layer is the layer of material on the surface of a substrate that controls the alignment of a liquid crystal layer in the absence of an external field.
- a “conventional alignment layer” herein refers to an alignment layer that will only align a liquid crystal layer via processing other than optical means. For example, mechanically buffed polyimides, evaporated silicon dioxide, Langmuir- Blodgett films, have all been shown to align liquid crystals.
- Optical alignment layer herein refers to an alignment layer that contains anisotropically absorbing molecules that will induce alignment of liquid crystals after exposure with polarized light.
- Optical alignment layers may be processed by conventional means, such as mechanical rubbing, prior to or after exposure to polarized light.
- the anisotropically absorbing molecules of the optical alignment layers exhibit absorption properties with different values when measured along axes in different directions.
- the anisotropic absorbing molecules exhibit absorption bands between 150 nm and about 2000 nm.
- the anisotropically absorbing molecules of the optical alignment layer can be covalently bonded within a main chain polymer, they can be covalently bonded as side groups to a main polymer chain, they can be present as nonbonded solutes in a polymer, or they can be in the adjacent liquid crystal layer as a solute and adsorbed on the surface of a normal alignment layer to give an optical alignment layer.
- Preferred optical alignment layers have absorbance maxima of about from 150 to 1600 nm. More preferable optical alignment layers have absorbance maxima of about from 150 nm to 800 nm. Most preferable optical alignment layers for the present invention have absorbance maxima of about from 150 and 400 nm and especially about from 300 to 400 nm.
- polyimides are known for their excellent thermal and electrical stability properties and these properties are useful in optical alignment layers for liquid crystal displays.
- the preparation of polyimides is described in "Polyimides", D. Wilson, H. D. Stenzenberger, and P. M. Hergenrother Eds., Chapman and Hall, New York (1990).
- polyimides are prepared by the condensation of one equivalent of a diamine with one equivalent of a dianhydride in a polar solvent to give a poly(amic acid) prepolymer intermediate.
- the poly(amic acid) is typically formulated to give a 1 to 30 wt % solution.
- the condensation reaction is usually performed between room temperature and 150°C.
- the prepolymer solution is coated onto a desired substrate and thermally cured at between 180 and 300°C to complete the imidization process.
- the poly(amic acid) prepolymer is chemically imidized by addition of a dehydrating agent to form a polyimide polymer.
- the molar ratio of diamine to dianhydride usually is 1:1, but can vary between 0.8:1 to 1.2:1.
- the preferred ratio of diamine to dianhydride is between 0.9:1 and 1.1:1
- Preferred in the process of this invention is a polyimide polymer of structure I comprising the reaction product of at least one tetracarboxylic dianhydride and a diamine component, wherein the diamine component comprises a 2-substituted 1 ,4- benzenediamine wherein the 2-substituent X, is an electron withdrawing group having a positive ⁇ , and M is a tetravalent organic radical derived from said tetracarboxylic dianhydride containing at least two carbon atoms, no more than two carbonyl groups of the dianhydride being attached to any one carbon atom of the tetravalent radical.
- Example 1 and 2 show superior alignment quality to Examples 3 and 4, respectively.
- These results indicate electron withdrawing groups in 2-substituted- 1 ,4-benzenediamines give polyimides that are substantially superior in the optical alignment process than polyimides derived from 5-substituted-l,3-benzenediamines.
- polyimides of structure I wherein X is selected from the group -CN, -CF 3 , F, Cl, Br, I, -NO 2 , -CO 2 R, and -CON(R) 2 , wherein R is H or a C, - C 4 hydrocarbon.
- polyimides of structure I wherein X, is selected from the group -CN and -CF are preferred in the process of this invention.
- Preferred in the process of this invention is a polyimide polymer that is a homopolyimide or a copolyimide of at least one diaryl ketone tetracarboxylic dianhydride and at least one diamine, which comprises at least one structural element of formula III:
- Q' is a divalent organic radical derived from said diamine containing at least two carbon atoms
- X is independently selected from the group consisting of H. Cl, F, Br, R j and R ] O-; wherein R
- Z is selected from the group consisting of -S-, -SO 2 -, -O-, -CH 2 CH 2 -,-CH 2 -, -NR-, -C(CF 3 ) 2 -, - C(O)-, or a covalent bond, wherein R is a C ⁇ - C4 hydrocarbon chain; and m is 1 or 0.
- compositions of this invention are polyamic acids of structure II
- X is -CN
- X 2 is independently selected from the group H, Cl, F, Br, R, and R,O-, wherein R, is independently selected from C, - C 3 perfluorinated alkyl chain, C, - C 3 partially fluorinated alkyl chain and C, - C 8 hydrocarbon chain
- m is 1 or 0
- Z is selected from the group -S-, -O-.
- compositions are wherein X 2 is H or Cl and m is 0.
- a most preferred polyamic acid composition is wherein the tetracarboxylic dianhydride is benzophenone-3,3'4,4'-tetracarboxylic dianhydride.
- polyimide polymers that are derived from 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,2'- dichloro-4,4',5,5'-benzophenone tetracarboxylic dianhydride. Both materials are colorless, provide reasonable solubility characteristics to the polyimides, and provide llic necessary photoactive UV chromophore in high concentration.
- benzophenonetetracarboxylic dianhydrides are readily available from commercial sources or synthesis.
- BTDA 3,3',4,4'-benzophenonetetracarboxylic dianhydride
- Aldrich Chemical Co., Inc. (1001 W. St. Paul Ave., Milwaukee, WI 53233).
- 2,2'-Dichloro-4,4',5,5'-benzophenone tetracarboxylic dianhydride is available from 4-chloro- ⁇ -xylene by Friedel-Crafts acylation with oxalyl chloride to give 2,2'-dichloro-4,4',5,5',-tetramethylbenzophenone, followed by oxidation with nitric acid and dehydration of the resulting tetracarboxylic acid as described by Falcigno, et al., J. Poly. Sci. 1992, 30, 1433.
- dianhydrides such as pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6- naphthalenetetracarboxyhc dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3 ,3'4,4'-biphenyltetracarboxylic dianhydride, 2,3 ,2',3'-biphenyltetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4- dicarboxyphenyl)diphenylsulfone dianhydride, bis(3 ,4-dicarboxyphenyl)methane dianhydride, 2,2-bis
- dianhydrides may be used in forming copolyamic acids.
- tetracarboxylic dianhydride components include aromatic dianhydrides such as pyromellitic dianhydride, 2,3,6,7- naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1 ,4,5,8-naphthalenetetracarboxylic dianhydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, 2,3,2',3'-biphenyltetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)diphenylsulfone dianhydride, bis(3,4- dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphen
- 2-(trifluoromethyl)-l,4-benzenediamine is available from PCR Inc. ( P.O. Box 1466, Gainesville, FL 32602); 2,5-diaminobenzonitrile is available from Frinton Laboratories (P.O. Box 2428, Vineland, NJ 08360); 2-nitro-l,4- phenylenediamine is available from Aldrich Chemical Co., 1001 West Saint Paul Ave., Milwaukee, WI 53233; 2-chloro-l,4-phenylene diamine is available from Chemetall Chemical Products Co., 50 Valley Rd., Berkley Heights, NJ 07922.
- diamines such as 2-fluoro-l,4-phenylene diamine, 2-bromo-l,4-phenylene diamine, methyl 2,5-diaminobenzoate, and 2,5-diaminobenzamide are available by synthesis.
- poly(amic acid) solutions or preimidized polyimide solutions are coated onto desired substrates. Coating is usually accomplished with 2 to 30 wt % solids. Any conventional method may be used to coat the substrates including brushing, spraying, spin-casting, dipping or printing.
- the coated substrates are heated in an oven under an inert atmosphere, for instance nitrogen or argon, at elevated temperature usually not exceeding 300°C and preferably at or below 180°C for about from 1 to 12 hours, preferably for about 2 hours or less.
- the heating process removes the solvent carrier and may be used to further cure the polymer.
- the poly(amic) acid films are thermally cured to generate polyimide films.
- polarized light is meant light that is elliptically polarized such that the light is more polarized along one axis (referred to as the major axis) versus the orthogonal axis (referred to as the minor axis).
- the preferred polarization is linearly polarized light where the light is polarized mostly along one axis (the major axis) with little or no polarization component along the minor axis.
- the polarized light has one or more wavelengths of about from 150 to 2000 nm and preferably of about from 150 and 1600 nm and more preferably about from 150 to 800 nm.
- the polarized light has one or more wavelengths of about from 150 to 400 nm, and especially about from 300 to 400 nm.
- a preferred source of light is a laser, e.g., an argon, helium neon, or helium cadmium.
- Other preferred sources of light are mercury arc deuterium and quartz tungsten halogen lamps, xenon lamps and black lights in combination with a polarizer.
- Polarizers useful in generating polarized light from nonpolarized light sources are interference polarizers made from dielectric stacks, absorptive polarizers and reflective polarizers based on Brewster reflection. With lower power lasers or when aligning small alignment regions, it may be necessary to focus the light beam onto the optical alignment layer.
- Exposure is meant that polarized light is applied to the entire optical alignment layer or to a portion thereof.
- the light beam may be stationary or rotated. Exposures can be in one step, in bursts, in scanning mode or by other methods. Exposure times vary widely with the materials used, etc., and can range from less than 1 msec to over an hour. Exposure may be conducted before or after contacting the optical alignment layer with the liquid crystal medium. Exposing can be accomplished by linearly polarized light transmitted through at least one mask having a pattern or with a beam of linearly polarized light scanned in a pattern. Exposing also may be accomplished using interference of coherent optical beams forming patterns, i.e., alternating dark and bright lines.
- Exposure energy requirements vary with the formulation and processing of the optical alignment layer prior and during exposure. For example, materials that possess high glass transition temperatures can have higher energy density requirements for optical alignment. Whereas, material systems designed to have a low glass transition temperature prior to exposure can have lower energy density requirements.
- a preferred range of exposure energy is about from 0.001 to 2000 J/cm ⁇ . More preferred is the range of about from 0.001 to 100 J/cm ⁇ and most preferred range of exposure energy is about from 0.001 to 5 J/cm ⁇ . Lower exposure energy is most useful in large scale manufacturing of optical alignment layers and liquid crystal display elements. Lower exposure energy also minimizes the risk of damage to other materials on the substrates.
- the efficiency of the alignment process, and the exposure energy required, may be further impacted by heating, beyond that inherent in the "exposing " ' step. Additional heating during the exposing step may be accomplished by conduction, convection or radiant heating, or by exposure to unpolarized light. Additional heating may increase the mobility of the molecules during exposure and improve the alignment quality of the optical alignment layer. Additional heating is not a requirement of the process of the invention but may give beneficial results.
- the Quality of alignment and electrical properties of the liquid crystal cell assembled from exposed substrates can be improved by heating the substrates after exposure but prior to assembly of the cell. This additional heating of the substrates is not a requirement of the process but may give beneficial results.
- Exposing also can consist of two or more exposure steps wherein the conditions of each step such as angle of incidence, polarization state, energy density, and wavelength are changed. At least one of the steps must consist of exposure with linearly polarized light. Exposures can also be localized to regions much smaller than the substrate size to sizes comparable to the entire substrate size.
- a preferred method of dual exposing comprises a two step process of:
- Another preferred method of dual exposing comprises a two step process of:
- Another preferred method of dual exposing comprises a two step process of:
- Another preferred method of dual exposing comprises a two step process of:
- Applying a liquid crystal medium to the optical alignment can be accomplished by capillary filling of a cell, by casting of a liquid crystal medium onto an optical alignment layer, by laminating a preformed liquid crystal film onto an optical alignment layer or by other methods.
- Preferred methods are capillary filling of a cell and casting of a liquid crystal medium onto an optical alignment layer.
- Optical alignment layers are pre-exposed to polarized light or they are exposed after contacting the liquid crystal medium.
- a cell can be prepared by using two coated substrates to provide a sandwiched layer of liquid crystal medium.
- the pair of substrates can both contain optical alignment layers or a conventional alignment layer (e.g., mechanically buffed) can be used as the second alignment layer comprising the same or a different polymer.
- a conventional alignment layer e.g., mechanically buffed
- liquid crystal substances used for liquid crystal optical elements nematic liquid crystal substances, ferroelectric liquid crystal substances, etc. are usable.
- Useful liquid crystals for the invention described herein include those described in U. S. Patent 5,032,009 and new superfluorinated liquid crystals available from EM Industries,
- the exposed optical alignment layer induces alignment of a liquid crystal medium at an angle + and - ⁇ with respect to the direction of the linear polarization of the incident light beam and along the plane of the optical alignment layer.
- One skilled in the art will recognize that the process of the instant invention allows control of the alignment of a liquid crystal medium in any desired direction within the plane of the optical alignment layer by controlling the conditions of the polarized light exposure.
- a liquid crystal display element made by the process of the instant invention is composed of an electrode substrate having at least one optical alignment layer, a voltage-impressing means and a liquid crystal material.
- Fig. 1 illustrates a typical liquid crystal display element, comprising a transparent electrode 2 of ITO (indium-tin oxide) or tin oxide on a substrate 1 and optical alignment layers 3 formed thereon. The optical alignment layers are exposed to polarized light of a wavelength or wavelengths within the absorption band of the anisotropically absorbing molecules.
- a spacer concurrently with a sealing resin 4 is intervened between a pair of optical alignment layers 3.
- a liquid crystal 5 is applied by capillary filling of the cell and the cell is sealed to construct a liquid crystal display element.
- Substrate 1 may comprise an overcoat film such as an insulating film, a color filter, a color filter overcoat, a laminated polarizing film etc. These coatings and films are all considered part of the substrate 1. Further, active elements such as thin film transistors, a nonlinear resistant element, etc. may also be formed on the substrate 1. These electrodes, undercoats, overcoats, etc. are conventional constituents for liquid crystal display elements and are usable in the display elements of this invention. Using the thus formed electrode substrate, a liquid crystal display cell is prepared, and a liquid crystal substance is filled in the space of the cell, to prepare a liquid crystal display element in combination with a voltage-impressing means.
- Table 2 Summary of liquid crystal alignment quality for optically aligned polyimides comprising various amines, including monoamines and diamines.
- the coated substrates were exposed to ultraviolet polarized light using the set-up schematically represented in Fig. 2.
- each coated substrate 7 was mounted onto a 2-axis XY translation stage (indicated by double-headed arrows 8 in Fig. 2) with the coated side facing the incident laser beam.
- An Innova 400 (Coherent Incorporated, Santa Clara, CA) laser 9 was tuned to lase in the ultraviolet with wavelengths ranging from 300 to 336 nm.
- the 1 cm polarized beam 10 was directed with mirror 11 to a 5 cm focal length cylindrical lens 12 which focused the incident 1 cm beam to a line (1 cm X 200 ⁇ m) onto each coated substrate 7.
- the coated substrate was translated at a 0.75 mm/s constant speed along the Y direction and then stepped in the X direction. This was repeated until the coated substrate had been completely exposed.
- the incident optical power was about 0.4 Watts and the ultraviolet light was polarized along 10.
- the substrates were assembled with orthogonal orientation of the optically generated alignment direction.
- the cell thickness was about 4 microns.
- the cell was subsequently capillary filled with nematic liquid crystals.
- the liquid crystals were observed to align in a twisted nematic orientation when viewed between polarizers.
- the uniformity of the alignment was observed to improve.
- the quality of the alignment for the cell is described in Table 2.
- two coated substrates were treated identically as described above except that the coated substrates were translated at 1.5 mm/s constant speed.
- the cell was fabricated as before and it was observed to align in a twisted nematic orientation when viewed between polarizers. Upon annealing the liquid crystal cell above the liquid crystal isotropic point (95 degrees C for 30 minutes), the uniformity of the alignment was observed to improve. The quality of the alignment for the cell is described in Table 2.
- Example 2 The quality of the alignment for the cell is described in Table 2.
- Example 5 3,5-diaminobenzonitrile, 4, (2.00 g) and ⁇ -butyrolactone (27.3 g) was stirred at room temperature for 24 h under a nitrogen atmosphere. The solution was diluted to a 10 wt % solution with ⁇ -butyrolactone (33.5 g) and filtered through a 0.45 micron teflon membrane filter. The solution was diluted to 3 wt % solution and spin coated as described in Example 1. The exposed substrates were assembled tested and evaluated as described in Example 1 and the results are listed in Table 2.
- Example 5 Example 5
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020007012988A KR20010025050A (en) | 1998-05-18 | 1999-05-14 | Process and materials for inducing alignment of liquid crystals and liquid crystal optical elements |
JP2000549682A JP2002515617A (en) | 1998-05-18 | 1999-05-14 | Method and material for inducing liquid crystal alignment, and liquid crystal optical element |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/080,639 | 1998-05-18 | ||
US09/080,639 US5958293A (en) | 1996-03-29 | 1998-05-18 | Process for inducing alignment of liquid crystals and liquid crystal optical elements |
US09/080,638 US5958292A (en) | 1998-05-18 | 1998-05-18 | Materials for inducing alignment of liquid crystals and liquid crystal optical elements |
US09/080,638 | 1998-05-18 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999060073A1 true WO1999060073A1 (en) | 1999-11-25 |
Family
ID=26763746
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1999/010752 WO1999060073A1 (en) | 1998-05-18 | 1999-05-14 | Process and materials for inducing alignment of liquid crystals and liquid crystal optical elements |
Country Status (3)
Country | Link |
---|---|
JP (1) | JP2002515617A (en) |
TW (1) | TWI230841B (en) |
WO (1) | WO1999060073A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001053384A1 (en) * | 2000-01-24 | 2001-07-26 | Rolic Ag | Photoactive polyimides, polyamide acids or esters with side chain photocrosslinkable groups |
US6985291B2 (en) | 2001-10-01 | 2006-01-10 | 3M Innovative Properties Company | Non-inverting transflective assembly |
CN100465726C (en) * | 2006-03-01 | 2009-03-04 | 财团法人工业技术研究院 | Reflective liquid-crystal display panel |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101267528B1 (en) | 2007-03-21 | 2013-05-23 | 엘지디스플레이 주식회사 | Method of fabricating of an alignment layer |
JP5316740B2 (en) * | 2007-08-30 | 2013-10-16 | Jsr株式会社 | Method for forming liquid crystal alignment film |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5276132A (en) * | 1991-03-11 | 1994-01-04 | Japan Synthetic Rubber Co., Ltd. | Liquid crystal aligning agent and aligning agent-applied liquid crystal display device |
US5731405A (en) * | 1996-03-29 | 1998-03-24 | Alliant Techsystems Inc. | Process and materials for inducing pre-tilt in liquid crystals and liquid crystal displays |
US5807498A (en) * | 1996-03-29 | 1998-09-15 | Alliant Techsystems Inc. | Process and materials for aligning liquid crystals and liquid crystal optical elements |
US5817743A (en) * | 1996-03-29 | 1998-10-06 | Alliant Techsystems Inc. | Process and materials for inducing pre-tilt in liquid crystals and liquid crystal displays |
-
1999
- 1999-05-14 JP JP2000549682A patent/JP2002515617A/en not_active Withdrawn
- 1999-05-14 WO PCT/US1999/010752 patent/WO1999060073A1/en not_active Application Discontinuation
- 1999-06-28 TW TW088108108A patent/TWI230841B/en not_active IP Right Cessation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5276132A (en) * | 1991-03-11 | 1994-01-04 | Japan Synthetic Rubber Co., Ltd. | Liquid crystal aligning agent and aligning agent-applied liquid crystal display device |
US5731405A (en) * | 1996-03-29 | 1998-03-24 | Alliant Techsystems Inc. | Process and materials for inducing pre-tilt in liquid crystals and liquid crystal displays |
US5807498A (en) * | 1996-03-29 | 1998-09-15 | Alliant Techsystems Inc. | Process and materials for aligning liquid crystals and liquid crystal optical elements |
US5817743A (en) * | 1996-03-29 | 1998-10-06 | Alliant Techsystems Inc. | Process and materials for inducing pre-tilt in liquid crystals and liquid crystal displays |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001053384A1 (en) * | 2000-01-24 | 2001-07-26 | Rolic Ag | Photoactive polyimides, polyamide acids or esters with side chain photocrosslinkable groups |
US6831148B2 (en) | 2000-01-24 | 2004-12-14 | Rolic Ag | Photoactive polyimides, polyamide acids or esters with side chain photocrosslinkable groups |
US6985291B2 (en) | 2001-10-01 | 2006-01-10 | 3M Innovative Properties Company | Non-inverting transflective assembly |
US7084938B2 (en) | 2001-10-01 | 2006-08-01 | 3M Innovative Properties Company | Non-inverting transflective assembly |
US7245431B2 (en) | 2001-10-01 | 2007-07-17 | 3M Innovative Properties Company | Reflective polarizer assembly |
CN100465726C (en) * | 2006-03-01 | 2009-03-04 | 财团法人工业技术研究院 | Reflective liquid-crystal display panel |
Also Published As
Publication number | Publication date |
---|---|
JP2002515617A (en) | 2002-05-28 |
TWI230841B (en) | 2005-04-11 |
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