WO2006070318A2 - Procede de fabrication d'un polariseur - Google Patents

Procede de fabrication d'un polariseur Download PDF

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Publication number
WO2006070318A2
WO2006070318A2 PCT/IB2005/054367 IB2005054367W WO2006070318A2 WO 2006070318 A2 WO2006070318 A2 WO 2006070318A2 IB 2005054367 W IB2005054367 W IB 2005054367W WO 2006070318 A2 WO2006070318 A2 WO 2006070318A2
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WO
WIPO (PCT)
Prior art keywords
reactive
molecules
mixture
polarizer
layer
Prior art date
Application number
PCT/IB2005/054367
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English (en)
Other versions
WO2006070318A3 (fr
Inventor
Rifat A. M. Hikmet
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2006070318A2 publication Critical patent/WO2006070318A2/fr
Publication of WO2006070318A3 publication Critical patent/WO2006070318A3/fr

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Classifications

    • 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
    • C09B67/0097—Dye preparations of special physical nature; Tablets, films, extrusion, microcapsules, sheets, pads, bags with dyes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/38—Polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C09K19/60—Pleochroic dyes
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3016—Polarising elements involving passive liquid crystal elements
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K2019/0444—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group
    • C09K2019/0448—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group the end chain group being a polymerizable end group, e.g. -Sp-P or acrylate

Definitions

  • the present invention relates to a method for manufacturing a polarizer. It also relates to polarizers manufactured by such a method as well as to optical devices comprising such polarizers.
  • Polarizers are widely used in many optical devices, such as liquid crystal displays and emissive displays, in order to enhance contrast.
  • the most common commercially available polarizers are made of highly uniaxially oriented polymeric materials containing dichroic dye molecules or crystals. They are then laminated onto the surfaces.
  • polarizers which can be coated onto patterned surfaces.
  • polarizers which can be brought onto a surface from a lyotropic liquid crystal phase has been suggested (Optiva).
  • dye molecules which can be mixed into a monomeric reactive liquid crystal mixture. Such a liquid mixture can be brought onto a surface at high speeds followed by polymerization using UV light.
  • One object of the invention is to provide a way to produce effective polarizers having reduced thickness.
  • a method for manufacturing a polarizer comprising: providing a liquid crystalline mixture comprising reactive molecules (1), non-reactive molecules (2), dichroic dye molecules (3), and a polymerization initiator; providing a uniaxially oriented film of said mixture; polymerizing said film; and removing at least part of said non-reactive molecules.
  • a gel which is composed of cross-linked polymer networks and dye molecules, and is swollen by the non-reactive molecules. Because of this swelling, the gel can take a relatively high concentration of dichroic dye molecules.
  • the method according to the invention therefore allows higher dye loading at a given thickness, and can result in a thinner polarizer with maintained dichroic ratio.
  • the uniaxially oriented film may be formed on a layer which induces planar uniaxial orientation (4).
  • the film may be formed on a rubbed polymer layer, such as a reactive polyimide layer, which induce uniaxial macroscopic orientation in liquid crystal molecules.
  • the uniaxially oriented film may also be formed on a photoalignment layer.
  • the weight ratio of the reactive and non-reactive molecules is in the range of 10:1 to 1:10, and the concentration of dichroic molecules is in the range of 0.1 - 10% by weight.
  • the reactive molecules may be selected from the molecules disclosed in table 1.
  • the reactive molecule is a liquid crystalline diacrylate, epoxy, vinyl ether or thiolene system.
  • a specific example of a reactive molecule, C6M, is shown in table 3.
  • the polymerization may be induced by ultraviolet (UV) radiation, gamma rays, x-rays, electron beams, or heat.
  • UV ultraviolet
  • gamma rays gamma rays
  • x-rays x-rays
  • electron beams or heat.
  • the removal of non-reactive molecules may be effected by heating or solvent extraction.
  • the invention also relates to a polarizer obtainable by the above-described method, as well as to an optical device comprising such a polarizer.
  • FIG. Ia-Ic is a schematic illustration of the method for manufacturing a polarizer according to the invention, showing cross-sections of the manufactured polarizer,
  • Fig. 2 and Fig. 3 show the results from the examples 1 and 2, where the absorbance corresponding to parallel and perpendicular arrangement of the polarization direction with respect to molecular alignment is shown, Figs. 4 to 7 show the properties of various networks containing dye molecules, Fig. 8 shows the dichroic ratio (absorbance parallel/absorbance perpendicular) as a function of wavelength for different materials.
  • the present inventors have found that advantageously an anisotropic gel system may be used for producing thin polarizers.
  • the method comprises the following main steps: providing a liquid crystalline mixture comprising reactive molecules (1), non-reactive molecules (2), dichroic dye molecules (3), and a polymerization initiator; providing a uniaxially oriented film of said mixture; polymerizing said film; and removing at least part of said non-reactive molecules.
  • a liquid crystalline mixture containing reactive molecules (1) and non-reactive molecules (2).
  • the reactive molecule (2) may be a cross-linkable mesogen, e.g. a liquid crystal diacrylate.
  • the expression "reactive molecule” relates to a molecule with at least one reactive group which, in the presence of a suitable initiator, leads to polymerization of the molecule upon exposing it to high energy radiation, such as ultraviolet light, electron beams, x-rays, or simply by heating.
  • Suitable examples of reactive molecules are shown in table 1. More specifically, the reactive molecule is suitably a liquid crystalline diacrylate, epoxy, vinyl ether or thiolene system. For example C6M, the structural formula of which is shown in table 3, may be used.
  • the non-reactive molecule (2) may be a non-reactive mesogen, and may be selected from any conventional LC-molecules, such as those used in liquid crystal display cells.
  • the expression "non-reactive molecule” relates to a molecule which does not have reactive groups and does not get polymerized.
  • a mesogen is a compound that under suitable conditions can exist as a mesophase (liquid crystal phase), i.e. a phase occurring within the mesomorphic state.
  • the mesomorphic state is a state in which the degree of molecular order is intermediate between the perfect three-dimensional, long-range positional and orientational order found in solid crystals and the absence of long-range order found in isotropic liquids, gases, and amorphous solids.
  • thermotropic liquid crystals a mesophase can be observed in a certain temperature range.
  • a maximum amount of dichroic dye molecules (3) is dissolved.
  • the concentration of the dichroic molecules in the mixture is suitably in the range of 0.1 to 10 % by weight, or in the range of 2-6% by weight.
  • suitable dichroic molecules are shown in table 2.
  • the expression "dichroic” relates to a property of a substance in which one polarized component of incident light is absorbed to a different extent than the other polarization component.
  • the amount of reactive and non-reactive molecules shall be effective to dissolve the dichroic dye.
  • the weight ratio of the reactive and non-reactive mesogens may be in the range of 10:1 to 1 : 10, or in the range of 4:1 to 1:4.
  • the mixture is also provided with an initiator for polymerization (not shown in
  • Such an initiator can produce suitable species (ions, radicals) to induce polymerization when heated or subjected to radiation.
  • suitable species ions, radicals
  • polymerization initiators are peroxides, such as benzoyl peroxide, and azo compounds, such as AIBN.
  • Photo initiators, such as ⁇ , ⁇ - dimethoxydeoxybenz ⁇ , can also be used, as well as cationic initiators, such as diphenyliodonium tetraiuluoroborate.
  • the mixture shall be formed into an uniaxially oriented film (Fig. Ia).
  • a layer which induces planar uniaxial orientation (4) The uniaxially oriented film may for example be formed on a uniaxially rubbed polymer layer, such as a polyimide layer, which induce uniaxial macroscopic orientation in liquid crystal molecules.
  • the uniaxially oriented film may be obtained by placing said mixture in a cell produced by placing glass plates provided with uniaxially rubbed polyimide layers on top of each other separated by 10 ⁇ m thick spacers.
  • uniaxial macroscopic orientation in the direction of the rubbing is induced within the liquid crystal.
  • uniaxial orientation can also be induced in a thin liquid crystal film by simply placing it on top of a rubbed polyimide layer.
  • a uniaxially oriented film can also be obtained on so-called photo-orientable layers, i.e. photo alignment layers. Such layers are obtained upon exposure to polarized light. They tend to induce macroscopic orientation in liquid crystal molecules brought on top of them. Various other techniques are also known to those working in the field.
  • the expression "uniaxially oriented film” relates to a molecule system where the long axis of the molecules is orientated macroscopically on average in the same direction. Thereafter, the system is polymerized in the oriented state to form a polymer network containing free molecules. Thereby, a uniaxially oriented polymerized film comprising uniaxially oriented dye molecules and non-reactive molecules are obtained (Fig. 2b).
  • the polymerization is suitably effected by ultraviolet radiation. However, other polymerization methods may be used, e.g. gamma rays, x-rays, electron beam, or thermal polymerization.
  • the polymerization may e.g. be induced by ultraviolet(UV) radiation at room temperature. Under the influence of UV radiation the photo initiator present in the mixture forms radicals which start the polymerization of the reactive groups.
  • the mixture according to the invention shows a stable liquid crystal phase with a high order parameter making material processing at room temperature possible.
  • liquid crystal phases There are many liquid crystal phases reported in the literature. Nematic, Smectic-A, smectic-B are the most known phases where the long axis of the molecules are oriented along a common average axis. Nematic phase has a lower order parameter than smectic-A phase and smectic-B phase shows the highest order.
  • the gel is composed by cross-linked anisotropic networks and dye molecules swollen by the non-reactive molecules.
  • the system is heated to evaporate the free liquid crystalline molecules, i.e. the non-reactive mesogens, leaving the network and the dye molecules behind (Fig. Ic).
  • the thickness of the polymerized film is thereby reduced to form the thin film dichroic polarizer.
  • a shrinkage of the film in the magnitude of 75% may be obtained.
  • the non-reactive molecules may also be removed by extraction using a suitable solvent.
  • the heating may be performed under a protecting atmosphere, e.g. under a nitrogen atmosphere, in order to prevent degradation of the dye molecules.
  • the reduction of the film is uniaxial.
  • the adhesion between the surface and the gel should be high. High adhesion is obtained by forming the gel film on a reactive polyimide layer.
  • the layer which induces planar uniaxial orientation is made of a material which polymerizes with the molecules of the gel the adhesion is increased, and a uniaxial shrinkage of the gel is promoted, i.e. only the thickness of the gel decreases.
  • X is selected from the group consisting of:
  • p is an integer in the range of 1-20.
  • R is selected from the group consisting of H, CH 3 and Cl, and M is selected from the group consisting of:
  • rings can be benzene or cyclohexane, which might have substitutions .
  • Example 1 and 2 A liquid crystalline mixture was made by mixing the eutectic mixture E44
  • Fig. 2 shows the absorbance corresponding to parallel and perpendicular arrangement of the polarization direction with respect to molecular alignment for the first experiment.
  • Fig. 3 shows the result of the second example.
  • thin and effective polarizers can be made.
  • Example 3 In order to compare properties of various networks containing dye molecules, the following experiments were performed.
  • a reactive acrylate C6M containing 4% dye molecules (S-409) was prepared and polymerized at 100 0 C. The spectra are shown in Fig 4.
  • the mixture described in example 3:1 (4% dye in C6M) was mixed with E7 (obtained from BDH/MERCK, consisting a mixture of cyano biphenyl and terphenyl compounds) to a weight ratio of 1 : 1.
  • the mixture was than polymerized.
  • the absorbance of the polymerized gel is shown in Fig 5.
  • Example 3 3
  • the non reactive molecules (E7) were extracted by gradual heating of the gel to 190 0 C. This was done under nitrogen atmosphere in order to reduce/prevent degradation of the dye molecules.
  • the spectra of the extracted gel is shown in fig. 6.
  • Example 3:4 During the evaporation described in example 3:3 it could be seen that the gel shrunk. In order to prevent this a reactive polyimide layer was used. In this way shrinkage could be prevented.
  • the absorbance of extracted gel is shown in fig 7.
  • the network obtained by polymerization of pure C6M was compared with the network obtained after extraction of E7 from the gel. This was done by measuring the weight gain of the networks after soaking them in chloroform. In the case of a pure network a weight increase of 3% was observed after soaking it in chloroform. In the case of a network obtained by extraction, a weigh increase of 83% was observed. This result clearly shows that the network obtained according to the present invention is very different from the network obtained by polymerization of pure C6M. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent for one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Abstract

La présente invention se rapporte à un procédé de fabrication d'un polariseur. Ce procédé consiste à se doter d'un mélange cristallin liquide contenant des molécules réactives, des molécules non réactives, des molécules d'un agent de coloration dichroïque et un amorceur de polymérisation; à utiliser un film orienté non axialement dudit mélange; à polymériser ledit film et à retirer au moins une partie desdites molécules non réactives. L'invention se rapporte également à des polariseurs fabriqués conformément à ce procédé ainsi qu'à des dispositifs optiques comprenant de tels polariseurs.
PCT/IB2005/054367 2004-12-29 2005-12-21 Procede de fabrication d'un polariseur WO2006070318A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP04107035.0 2004-12-29
EP04107035 2004-12-29

Publications (2)

Publication Number Publication Date
WO2006070318A2 true WO2006070318A2 (fr) 2006-07-06
WO2006070318A3 WO2006070318A3 (fr) 2006-09-08

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PCT/IB2005/054367 WO2006070318A2 (fr) 2004-12-29 2005-12-21 Procede de fabrication d'un polariseur

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WO (1) WO2006070318A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015227947A (ja) * 2014-05-30 2015-12-17 富士フイルム株式会社 積層体およびその製造方法、偏光板、液晶表示装置、有機ｅｌ表示装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6245399B1 (en) * 1998-10-14 2001-06-12 3M Innovative Properties Company Guest-host polarizers
EP1256602A1 (fr) * 2001-05-08 2002-11-13 Rolic AG Mélange dichroique
US20040135117A1 (en) * 2002-12-27 2004-07-15 Industrial Technology Research Institute Dichroic dye, composition thereof, and liquid crystal composition and liquid crystal display element containing the same
EP1462485A1 (fr) * 2003-03-26 2004-09-29 Rolic AG Colorants azo dichroiques polymerisables

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6245399B1 (en) * 1998-10-14 2001-06-12 3M Innovative Properties Company Guest-host polarizers
EP1256602A1 (fr) * 2001-05-08 2002-11-13 Rolic AG Mélange dichroique
US20040135117A1 (en) * 2002-12-27 2004-07-15 Industrial Technology Research Institute Dichroic dye, composition thereof, and liquid crystal composition and liquid crystal display element containing the same
EP1462485A1 (fr) * 2003-03-26 2004-09-29 Rolic AG Colorants azo dichroiques polymerisables

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015227947A (ja) * 2014-05-30 2015-12-17 富士フイルム株式会社 積層体およびその製造方法、偏光板、液晶表示装置、有機ｅｌ表示装置

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WO2006070318A3 (fr) 2006-09-08
TW200634394A (en) 2006-10-01

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