JP4390540B2 - OPTICAL ELEMENT AND ITS MANUFACTURING METHOD, AND LIQUID CRYSTAL ORIENTATION SUBSTRATE AND LIQUID CRYSTAL DISPLAY - Google Patents

Description

  The present invention relates to an optical element having a birefringence layer, a method for producing the same, a liquid crystal alignment substrate having the birefringence layer, and a liquid crystal display device including the liquid crystal alignment substrate. The invention also relates to a birefringent material.

  The liquid crystal display device is attracting attention as a flat panel display because it is easy to reduce the thickness and weight and consumes little power, and it is easy to suppress the occurrence of flicker, and as a display device of a personal computer or a television receiver. As the market is expanding rapidly. In addition, liquid crystal display devices are becoming larger.

  Liquid crystal display devices of various display modes have been developed. Since the liquid crystal has birefringence, the liquid crystal display device of any display mode basically has a viewing angle dependency. A large-sized liquid crystal display device has a wider practical viewing angle than a small-sized liquid crystal display device. Therefore, as the size of the liquid crystal display device increases, the demand for improved viewing angle dependency increases. For this reason, in parallel with the development of the liquid crystal display device, various techniques for improving the viewing angle characteristics have been developed.

  For example, as a liquid crystal display device with a wide viewing angle by controlling the alignment of the liquid crystal, a liquid crystal display device of a multi-domain system that divides the liquid crystal in the pixel into a plurality of regions having different alignment directions at least in halftone display, 2. Description of the Related Art An IPS (In-Plane Switching) type liquid crystal display device is known in which a horizontal electric field (an electric field parallel to a substrate surface) is formed in a cell to control liquid crystal alignment.

  Various optical elements having birefringence have been developed in order to optically compensate for incident light to the liquid crystal cell or light emitted from the liquid crystal cell to achieve a wide viewing angle. Conventionally, as this optical element, an optical compensation liquid crystal cell or an optical compensation film made of an optically uniaxial or biaxial stretched resin film has been used, but in recent years, it has been formed of a liquid crystal material. An optical element having a birefringent layer and a manufacturing method thereof have also been developed.

  For example, Patent Document 1 describes a viewing angle compensation film made of a nematic liquid crystal polymer having a positive intrinsic refractive index value in which molecular chains are aligned in the normal direction of the film surface. Patent Document 2 discloses a homeotropic alignment that can be used as an optical film by forming a vertical alignment film using a long-chain alkyl-type dendrimer derivative and coating a polymerizable liquid crystal compound on the vertical alignment film. A method of manufacturing a liquid crystal layer is described.

  Patent Document 3 discloses a side chain type liquid crystal polymer containing a monomer unit containing a liquid crystalline fragment side chain and a monomer unit containing a non-liquid crystalline fragment side chain on a substrate not provided with a vertical alignment film. A method is described in which a homeotropic alignment liquid crystal film that can be used as an optical film is manufactured by coating and further aligning the liquid crystal polymer in a liquid crystal state and then fixing the liquid crystal polymer while maintaining the alignment state. Has been.

In Patent Document 4, a binder layer and an anchor coat layer are formed on a substrate in this order, and a specific side chain type liquid crystal polymer is applied to the anchor coat layer to perform homeotropic alignment, followed by homeotropic alignment state. A method is described in which a homeotropic alignment liquid crystal film that can be used as an optical film is produced while being fixed.
JP-A-5-142531 JP 2002-174724 A JP 2002-174725 A JP 2003-121852 A

  However, in order to obtain the viewing angle compensation film described in Patent Document 1, an empty cell is prepared using two substrates each having a vertical alignment film, and a nematic liquid crystal monomer is filled in the empty cell. The nematic liquid crystal monomer must be vertically aligned and then photopolymerized, and then the nematic liquid crystal polymer (viewing angle compensation film) must be taken out from the cell. For this reason, the viewing angle compensation film described in Patent Document 1 has a problem that the process steps are long and the production cost increases.

  In order to manufacture a homeotropic alignment liquid crystal layer by the method described in Patent Document 2, a vertical alignment film must be provided, and a special and difficult-to-obtain material such as a long-chain alkyl dendrimer derivative is used. A vertical alignment film must be formed. For this reason, the manufacturing method of the homeotropic alignment liquid crystal layer described in Patent Document 2 has a problem that the production cost tends to increase.

  Since the homeotropic alignment liquid crystal film obtained by the method described in Patent Document 3 is composed of a side-chain liquid crystal polymer, its birefringence characteristics are easily affected by heat, and the temperature at which the desired birefringence characteristics can be maintained. The range is relatively narrow. For this reason, for example, it is difficult to use for a liquid crystal display device that requires relatively high heat resistance such as an in-vehicle liquid crystal display device. The homeotropic alignment liquid crystal film obtained by the method described in Patent Document 3 has a problem that the use of a liquid crystal display device that can use the homeotropic alignment liquid crystal film is limited.

  Side-chain liquid crystal polymers also have increased fluidity as the temperature rises even when the molecules are fixed in a homeotropic orientation state, so that the adhesion to the underlying layer is reduced, and birefringence characteristics are reduced due to residual stress. It will drop significantly. Accordingly, when the homeotropic alignment liquid crystal film is used for a liquid crystal display device, it must be formed outside the liquid crystal cell after the liquid crystal cell is manufactured so that the once formed homeotropic alignment liquid crystal film is not exposed to a high temperature environment. Don't be. For this reason, the homeotropic alignment liquid crystal film obtained by the method described in Patent Document 3 also has a problem that the degree of freedom in selecting a member that can form the homeotropic alignment liquid crystal film is low.

  Since the homeotropic alignment liquid crystal film obtained by the method described in Patent Document 4 is composed of a side chain type liquid crystal polymer, the same problems as the homeotropic alignment liquid crystal film obtained by the method described in Patent Document 3 described above are present. Have. In addition, in order to obtain a homeotropic alignment liquid crystal film by the method described in Patent Document 4, a binder layer and an anchor layer must be formed on the substrate in this order. For this reason, the manufacturing method of the homeotropic alignment liquid crystal film described in Patent Document 4 also has a problem that the production cost tends to increase.

  The present invention has been made to solve the above-described problems, and a first object of the present invention is to provide an optical element that can easily reduce production costs and whose birefringence characteristics are not easily affected by heat. There is.

  A second object of the present invention is to provide a method of manufacturing an optical element that is easy to suppress production costs and whose birefringence characteristics are not easily affected by heat.

  A third object of the present invention is to provide a liquid crystal alignment substrate that can obtain a liquid crystal display device having excellent viewing angle characteristics or light utilization efficiency and having relatively high heat resistance at low cost.

  A fourth object of the present invention is to provide a liquid crystal display device that can obtain a display having excellent viewing angle characteristics or light utilization efficiency and having relatively high heat resistance at low cost.

  A fifth object of the present invention is to provide a birefringent material that is easy to suppress production costs and whose birefringence characteristics are not easily affected by heat.

  The optical element of the present invention that achieves the first object is an optical element having a light-transmitting substrate and a first birefringence layer formed on the substrate, wherein the first element The birefringent layer is composed of a crosslinked polymer containing a coupling agent and a surfactant capable of homeotropic alignment of a polymerizable liquid crystal having a rod-like molecular shape, and the crosslinked polymer has a rod-like molecular shape. The polymerizable liquid crystal has a three-dimensionally crosslinked structure while maintaining a homeotropic alignment state.

  Since the first birefringent layer in the optical element of the present invention contains the above-described coupling agent and surfactant, this first birefringent layer is formed by homeotropic alignment of a polymerizable liquid crystal having a rod-like molecular shape. Even without using a vertical alignment film for the purpose, the coating composition can be formed by a comparatively simple method of sequentially applying, aligning, and crosslinking. The viewing angle compensation film described in Patent Document 1 is one in which an empty cell having a vertical alignment film is filled with a nematic liquid crystal monomer to vertically align the nematic liquid crystal monomer. In the optical element of the present invention, a polymerizable liquid crystal is used. Since it is not necessary to use an empty cell for homeotropic alignment, the manufacture thereof is easy. In addition, since the first birefringence layer has a three-dimensionally crosslinked structure, the birefringence characteristics are not easily affected by heat. Therefore, according to the optical element of the present invention, it is possible to provide an optical element which can easily reduce the production cost and whose birefringence characteristics are hardly affected by heat.

  In the optical element of the present invention, (1) the substrate is a glass substrate, or (2) the substrate has a silicon oxide film, and the first birefringence is formed on the silicon oxide film. It is preferable that the rate layer is formed.

  According to the above inventions (1) to (2), the above-mentioned polymerizable liquid crystal can be easily homeotropically aligned when the first birefringence layer is formed.

In the optical element of the present invention, (3) the tilt angle of the polymerizable liquid crystal molecules as the structural unit in the first birefringence layer is substantially uniform in the thickness direction of the first birefringence layer. (4) Further, a light absorbing color filter is formed on the light transmissive substrate , (5) the light absorbing color filter is on the light transmissive substrate, Or directly formed on the first birefringence layer, and (6 ) a second birefringence having a birefringence characteristic different from that of the first birefringence layer on the light-transmitting substrate. A refractive index layer is formed , (7) further comprising a light absorption color filter, and the light absorption color filter is directly formed on the second birefringence layer, or (8) ) The second birefringent layer is provided on the substrate having the light transmission property. The horizontal alignment film, or be directly formed on the first birefringence layer may be a. In the present invention, the “thickness direction of the first birefringence layer” means the normal direction of the surface of the first birefringence layer.

  The manufacturing method of the optical element of the present invention that achieves the second object described above is the above-described manufacturing method of the optical element of the present invention, and includes a preparation step of preparing a base material having optical transparency, and the base material Furthermore, it contains a polymerizable liquid crystal having a rod-like molecular shape, a coupling agent capable of homeotropic alignment of the polymerizable liquid crystal, and a surfactant capable of homeotropic alignment of the polymerizable liquid crystal. An alignment step of forming a coating film of the coated composition and homeotropically aligning the polymerizable liquid crystal in the coating film, and the polymerizable liquid crystal with the polymerizable liquid crystal in the coating film being homeotropically aligned. And a cross-linking step of three-dimensionally cross-linking.

  According to the method for producing an optical element of the present invention, the coating composition is applied, aligned, and crosslinked sequentially without using the vertical alignment film for homeotropic alignment of the polymerizable liquid crystal described above. Since a desired birefringence layer can be formed by a simple operation, the above-described optical element of the present invention can be easily manufactured.

The liquid crystal alignment substrate of the present invention that achieves the above third object is a liquid crystal alignment substrate comprising at least a light-transmitting substrate and a liquid crystal alignment film formed on one surface of the substrate. The first birefringence layer in the optical element of the present invention described above is provided between the substrate and the alignment film for liquid crystal or on the surface opposite to the one surface of the substrate. It is formed.

  According to the liquid crystal alignment substrate of the present invention, the first birefringence layer can be used as a layer for controlling the polarization state of light, such as an optical compensation layer or a retardation layer. A liquid crystal display device having excellent light utilization efficiency and relatively high heat resistance can be obtained at low cost.

In the substrate for liquid crystal alignment of the present invention, (i) when the first birefringence layer is formed between the substrate and the alignment film for liquid crystal, the first compound is formed on one surface of the substrate. A refractive index layer is formed, a light absorption color filter is formed on the first birefringence layer, and the liquid crystal alignment film is formed so as to cover the light absorption color filter, or (Ii) When the first birefringence layer is formed between the substrate and the liquid crystal alignment film, a light absorption color filter is formed on one surface of the substrate, and the light absorption color The first birefringence layer is formed on the filter via a silicon oxide film, and the liquid crystal alignment film is formed so as to cover the first birefringence layer. .

  The liquid crystal display device of the present invention that achieves the fourth object described above has a first liquid crystal alignment substrate located on the display surface side and a second liquid crystal alignment substrate located on the back side. A liquid crystal display device comprising: at least one of the first liquid crystal alignment substrate and the second liquid crystal alignment substrate is the liquid crystal alignment substrate of the present invention described above. .

  According to the liquid crystal display device of the present invention, since the liquid crystal alignment substrate of the present invention described above is included, a display device having excellent viewing angle characteristics or light utilization efficiency and having relatively high heat resistance can be obtained at low cost. It becomes possible.

  The birefringent material of the present invention that achieves the fifth object described above consists of a crosslinked polymer containing a coupling agent and a surfactant capable of homeotropic alignment of a polymerizable liquid crystal having a rod-like molecular shape, The cross-linked polymer has a structure in which a polymerizable liquid crystal having a rod-like molecular shape is three-dimensionally cross-linked while maintaining a homeotropic alignment state.

  The birefringent material of the present invention forms the first birefringence layer in the optical element of the present invention described above. Therefore, according to the birefringent material of the present invention, for the same reason as described in the description of the optical element of the present invention, it is easy to suppress the production cost and the birefringence characteristics are affected by heat. Difficult birefringent materials can be obtained.

  According to the optical element of the present invention and the method of manufacturing the optical element of the present invention, it is possible to provide an optical element that is easy to suppress the production cost and whose birefringence characteristics are not easily affected by heat. It is easy to inexpensively provide a specific optical element used for controlling the polarization state of light in various fields, that is, an optical element that is optically uniaxial and whose optical axis is in the thickness direction of the element. It becomes easy to improve the reliability.

  In addition, according to the liquid crystal alignment substrate of the present invention, it is possible to obtain a liquid crystal display device having excellent viewing angle characteristics or light utilization efficiency and relatively high heat resistance at low cost. In addition, it becomes easy to provide a liquid crystal display device that can be used for various purposes at low cost.

  According to the liquid crystal display device of the present invention, it is possible to obtain a display having excellent viewing angle characteristics or light utilization efficiency and having relatively high heat resistance at low cost. It becomes easy to provide what can be used for a low cost.

  According to the birefringent material of the present invention, it is possible to obtain a birefringent material that is easy to suppress the production cost and whose birefringence characteristics are not easily affected by heat. It is easy to inexpensively provide a specific optical element used for controlling the polarization state, that is, an optical element that is optically uniaxial and whose optical axis is in the thickness direction of the element, and its reliability is improved. It becomes easy to increase.

  Hereinafter, the optical element of the present invention, the method for producing the optical element of the present invention, the substrate for liquid crystal alignment of the present invention, the liquid crystal display device of the present invention, and the birefringent material of the present invention will be referred to as appropriate. Detailed description.

<Optical element (first form) and birefringent material>
FIG. 1A is a schematic view showing an example of a basic cross-sectional structure of the optical element of the present invention. The optical element 10 shown in the figure has a base material 1 having light permeability and a first birefringence layer 5 formed on the base material 1.

  The substrate 1 can have a single-layer structure or a multi-layer structure depending on the application of the optical element 10 or the like. When the substrate 1 has a single layer structure, the substrate 1 is preferably formed of glass or silicon oxide. When the base material 1 has a multi-layer structure, the structure can be appropriately selected according to the use of the optical element to be manufactured, and even in this case, the layer serving as the base of the first birefringence layer 5 is It is preferable to form with glass or silicon oxide. The substrate 1 is preferably optically isotropic, but a light-shielding region or the like can be locally provided as necessary. The light transmittance of the substrate 1 can be appropriately selected according to the use of the optical element 10 or the like.

  The first birefringence layer 5 formed on the substrate 1 includes a coupling agent (not shown) and a surfactant (not shown) capable of homeotropic alignment of a polymerizable liquid crystal having a rod-like molecular shape. It is made of a cross-linked polymer (birefringent material of the present invention) containing (not shown).

  FIG. 1B is a cross-sectional view schematically showing the structure of the first birefringence layer 5. As shown in the figure, the crosslinked polymer forming the first birefringence layer 5 has rod-like polymerizable liquid crystal molecules 6 as structural units. This crosslinked polymer has a structure in which a polymerizable liquid crystal having a rod-like molecular shape is three-dimensionally crosslinked while maintaining a homeotropic alignment state. In FIG. 1B, for the sake of convenience, the bonding hands in each polymerizable liquid crystal molecule 6 are not shown.

  It is preferable that the tilt angle of each polymerizable liquid crystal molecule 6 as a structural unit in the first birefringence layer 5 is substantially uniform in the thickness direction of the first birefringence layer 5. Here, in the present invention, “the tilt angle of the polymerizable liquid crystal molecules as the structural unit is substantially uniform in the thickness direction of the first birefringent layer” means that the thickness of the first birefringent layer 5 is thick. It means that the retardation in the vertical direction is about 10 nm or less.

Since the polymerizable liquid crystal in the first birefringence layer 5 is three-dimensionally crosslinked while maintaining the homeotropic alignment state, the xyz orthogonal coordinates are obtained with the thickness direction of the first birefringence layer 5 as the z axis. when assuming the refractive index n _y in the refractive indices n _x and y-axis direction of the x-axis direction becomes substantially the same value, the refractive index of the z-axis direction, the refractive indices n _x, is larger than n _y. That is, the first birefringence layer 5 is a uniaxial birefringence layer having an optical axis in the thickness direction (z-axis direction), and functions as a so-called “+ C plate”.

Retardation occurs in the light incident on the first birefringence layer 5 at an incident angle larger than 0 °. Retardation are the optical path difference between ordinary light and extraordinary light in the first birefringence layer 5, the first thickness of the birefringence layer, the polymerizable birefringence [Delta] n (refractive index of ordinary light n _o of the liquid crystal molecules 6 The retardation of the optical element 10 can be controlled by appropriately selecting the difference between the refractive index _ne and the refractive index ne of the extraordinary light) and the orientation degree of the polymerizable liquid crystal molecules.

  In order to obtain such an optical element 10, in the present invention, a polymerizable liquid crystal in which the molecular shape is rod-shaped and each molecule has two or more functional groups (hereinafter, this polymerizable liquid crystal is referred to as “polyfunctional polymerizable liquid crystal”). It is preferable to form the first birefringence layer 5 by using. The birefringence Δn of the polymerizable liquid crystal molecules is preferably about 0.03 to 0.30, and more preferably about 0.05 to 0.20. Specific examples of such polyfunctional polymerizable liquid crystals include polymerizable liquid crystals represented by the formulas (I) to (V) shown in FIGS. 2 (a) to 2 (e). In addition, n in Formula (I)-(V) shows the numerical value of 2-6 all.

  If necessary, in addition to the polyfunctional polymerizable liquid crystal, a polymerizable liquid crystal in which the molecular shape is rod-shaped and each molecule has only one functional group (hereinafter, this polymerizable liquid crystal is referred to as “monofunctional polymerizable liquid crystal”). Can be used. In this case, the use amount of the monofunctional polymerizable liquid crystal is preferably in the range of about 1 to 50 mol%, more preferably in the range of about 5 to 20 mol%, based on the total amount of the polymerizable liquid crystal. preferable. By using the monofunctional polymerizable liquid crystal in combination, the alignment property of the entire polymerizable liquid crystal can be improved or lowered, so that the alignment property of the entire polymerizable liquid crystal can be easily controlled. Specific examples of the monofunctional polymerizable liquid crystal include polymerizable liquid crystals represented by the formulas (i) to (iv) shown in FIGS. 2 (f) to 2 (i). In addition, n in Formula (i)-(iv) shows the numerical value of 2-6 all.

  The first birefringence layer 5 includes the above-described polymerizable liquid crystal, a coupling agent capable of homeotropic alignment of a rod-shaped polymerizable liquid crystal, and a homeotropic alignment of a rod-shaped polymerizable liquid crystal. After forming a coating film of a coating composition containing at least a surfactant capable of being formed, and homeotropically aligning the polymerizable liquid crystal in the coating film, the polymerizable liquid crystal is three-dimensionally crosslinked in this state. Is obtained. If necessary, the coating composition may contain a photopolymerization initiator, a sensitizer, a polyfunctional monomer, and the like. By containing a polyfunctional monomer, the crosslinkability of the first birefringence layer 5 can be improved.

  The above coupling agent only needs to be capable of homeotropic alignment of a rod-shaped polymerizable liquid crystal, and the first birefringence layer 5 contains only one type of coupling agent. Alternatively, two or more kinds may be used. In order to homeotropically align the polymerizable liquid crystal, the polymerizable liquid crystal must be heated to the liquid crystal phase (nematic phase) once, so the coupling agent must have heat resistance that does not cause decomposition. is required. Further, since it is added to the polymerizable liquid crystal, it is preferably soluble in an organic solvent.

  Specific examples of this coupling agent include n-octyltrimethoxysilane, n-octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, n-dodecyltrimethoxysilane, n-dodecyltriethoxysilane, octadecyltri Examples include silane coupling agents obtained by hydrolyzing silane compounds such as methoxysilane and octadecyltriethoxysilane.

  From the viewpoint of homeotropic alignment of the polymerizable liquid crystal even when the thickness of the first birefringence layer 5 is increased, the coupling agent acts to homeotropic align the polymerizable liquid crystal having a rod-like molecular shape (hereinafter, This action is referred to as “alignment regulating force”). Specific examples of such a coupling agent include perfluoroalkylsilane, pentafluorophenyltrimethoxysilane, pentafluorophenyltriethoxysilane, pentafluorophenylpropyltrimethoxysilane, pentafluorophenylpropyltriethoxysilane, trifluoropropyltrimethoxy. Silane, trifluoropropyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoro-oxy Rutrimethoxysilane, 1H, 1H, 2H, 2H-perfluoroosyltriethoxysilane, 3- (peptafluoroisopropoxy) propyltrimethoxysilane, and 3- (peptaful) Roisopuropokishi) propyltrimethoxysilane fluorinated silane compound a fluorine-based silane coupling agent obtained by hydrolysis of ethoxy silane (silane coupling having a fluorinated alkyl group agent) and the like.

  By using a coupling agent having a strong alignment regulating force, the above-mentioned polymerizable liquid crystal can be easily homeotropically aligned when the first birefringence layer 5 is formed. In addition, since the polymerizable liquid crystal can be homeotropically aligned even when the thickness of the first birefringent layer 5 is increased, the degree of freedom in selecting the thickness of the first birefringent layer 5 is increased. It becomes easy to control various retardations of the optical element 10.

  The content of the coupling agent in the first birefringence layer 5 includes the material of the substrate 1 (the material of the base of the first birefringence layer 5), the thickness of the first birefringence layer 5, and the coupling used. Although it depends on the orientation regulating power of the agent, etc., it is preferably about 0.001 wt% to 5 wt%, preferably about 0.01 wt% to 1 wt% with respect to the total amount of the polymerizable liquid crystal. Further preferred. When a coupling agent is contained in a large amount, the polymerizable liquid crystal does not undergo homeotropic alignment, and phase separation occurs between a region that is homeotropically aligned and a region that is aligned in a state other than homeotropic alignment.

  On the other hand, as the surfactant to be contained in the first birefringence layer 5, any nonionic, cationic, anionic or the like can be used as long as it can homeotropically align the rod-shaped polymerizable liquid crystal. Even if it is a thing of this type | system | group, only 1 type of surfactant may be used and multiple types of surfactant may be used together. However, in order to homeotropically align the polymerizable liquid crystal, the polymerizable liquid crystal must be heated to the liquid crystal phase (nematic phase) once, so the surfactant has a heat resistance not to be decomposed at this time. It is necessary to be. Further, since it is added to the polymerizable liquid crystal, it is preferably soluble in an organic solvent.

  From the viewpoint of increasing the degree of freedom in selecting the film thickness of the first birefringence layer 5, the surfactant has a long-chain alkyl group, and has a side chain and a fluorine atom in the side chain. It is preferable to use a surfactant having strong water repellency or oil repellency, such as a surfactant.

  Specific examples of the surfactant having strong water repellency or oil repellency include (i) lecithin, (ii) octadecyldimethyl (3-trimethoxysilylpropyl) ammonium chloride, (iii) hexadecylamine, (iv) adecamine 4DAC- 85 (trade name of surfactant manufactured by Asahi Denka Kogyo Co., Ltd.), (v) Drypon 600E (trade name of surfactant manufactured by Nikka Chemical Co., Ltd.), (vi) Drypon Z-7 (manufactured by Nikka Chemical Co., Ltd.) Surfactant name), and (vii) NK guard NDN-7E (product name of surfactant manufactured by Nikka Chemical Co., Ltd.).

  By using a surfactant having strong water repellency or oil repellency, it becomes easy to homeotropically align the polymerizable liquid crystal when the first birefringence layer 5 is formed. In addition, since the polymerizable liquid crystal can be homeotropically aligned even when the thickness of the first birefringent layer 5 is increased, the degree of freedom in selecting the thickness of the first birefringent layer 5 is increased. It becomes easy to control various retardations of the optical element 10.

  The content of the surfactant in the first birefringence layer 5 is as follows: the material of the base material 1 (the base material of the first birefringence layer 5), the thickness of the first birefringence layer 5, and the coupling used. Depending on the orientation regulating force of the agent, etc., the mass ratio can be appropriately selected within the range of about 1/100 to 1/1 of the solid content of the coupling agent contained in the first birefringence layer 5. .

  The coupling agent described above mainly plays a role of homeotropic alignment of the polymerizable liquid crystal on the interface side between the first birefringence layer 5 and the substrate 1. The above-described surfactant mainly plays a role of homeotropic alignment of the polymerizable liquid crystal on the outer surface side of the first birefringence layer 5.

  The degree of crosslinking of the first birefringent layer 5 is preferably about 80 or more, and more preferably about 90 or more. The thickness of the first birefringence layer 5 is within a range in which the polymerizable liquid crystal can be homeotropically aligned, specifically, retardation in the thickness direction (however, it means retardation as the optical element 10). .) Is preferably selected within a range where it is about 10 nm or less, and more preferably selected within a range where the retardation is about 5 nm or less.

  In the optical element 10 described above, the first birefringence layer 5 can be formed by a comparatively simple method of sequentially applying the coating composition, aligning treatment, and crosslinking treatment, so that the production cost can be easily suppressed. . In addition, since the first birefringence layer 5 has a three-dimensionally cross-linked structure, the birefringence characteristics are not easily affected by heat.

  The optical element 10 can be used as an element for controlling the polarization state of light, such as a phase difference element and an optical compensation element, and has a relatively high heat resistance. It can also be used for an optical apparatus used in an environment where it tends to occur. Furthermore, since the heat resistance is relatively high, it can be provided in a display liquid crystal panel.

<Optical element (second form)>
FIG. 3 is a schematic view showing another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 15 shown in FIG. 1 has a light-transmitting substrate 1 having a light-transmitting substrate 1a and a silicon oxide film 1b formed on one surface of the light-transmitting substrate 1a. It differs from the optical element 10 of the first embodiment described above in that the first birefringence layer 5 is provided on the material film 1b. Since the other configuration is the same as that of the optical element 10 of the first embodiment, the description of the members common to the members shown in FIG.

  The light transmissive substrate 1a may be formed of either an inorganic material or an organic material, but the silicon oxide film 1b is provided when the light transmissive substrate 1a is neither glass nor silicon oxide. It is particularly preferred. The silicon oxide film 1b can be formed by, for example, physical vapor deposition or chemical vapor deposition.

  By using the silicon oxide film 1b as the base layer of the first birefringence layer 5, the desired first birefringence layer 5 is formed even when the light-transmitting substrate 1 is made of an organic material, for example. It becomes easy.

<Optical element (third embodiment)>
FIG. 4A is a schematic diagram showing still another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 30 shown in the figure can be used as, for example, a constituent member of a liquid crystal alignment substrate, and a first birefringence layer 25 is formed on a light-transmitting base material 21.

  The substrate 21 includes a light transmissive substrate 1a, a light absorption color filter 22 (hereinafter simply referred to as “color filter 22”) and a light shielding layer (black matrix) 23 formed on one surface of the light transmissive substrate 1a. And the silicon oxide film 1b formed so as to cover the color filter 22 and the light shielding layer 25. A first birefringence layer 25 is formed on the silicon oxide film 1b. The structure of the light transmissive substrate 1a, the silicon oxide film 1b, and the first birefringence layer 25 is the same as the light transmissive substrate 1a, the silicon oxide film 1b, or the first birefringence layer in the optical element 15 of the second form. Since this is the same as the configuration of 5, the description thereof is omitted here.

  The color filter 22 is a primary color system in which a red micro color filter 22R, a green micro color filter 22G, and a blue micro color filter 22B are arranged in a predetermined pattern, and each color micro color filter 22R, 22G, 22B. Depending on the arrangement form, various types of color filters called stripe type, mosaic type, triangle type and the like are known. It is also possible to use a complementary color filter instead of the primary color filter.

  The color filter 22 is formed by, for example, patterning a color resin coating film as a material for each color micro color filter 22R, 22G, 22B into a predetermined shape by, for example, a photolithography method, or for each color micro color filter Each of 22R, 22G, and 22B can be formed by applying a color filter ink as a material in a predetermined shape.

  The light shielding layer 23 is for preventing light leakage (leakage light) from between pixels in the display liquid crystal panel and light deterioration of the active elements in the active matrix drive type display liquid crystal panel. Individual pixels are defined in plan view in the liquid crystal panel. The micro color filters 22R, 22G, and 22B for the respective colors are arranged so as to cover predetermined pixels defined by the light shielding film 23 in plan view.

  The light shielding layer 23 can be formed, for example, by patterning a metal thin film having a light shielding property or a light absorbing property such as a metal chromium thin film or a tungsten thin film into a predetermined shape. It is also possible to form the light shielding layer 23 by printing an organic material such as a black resin in a predetermined shape. In addition, it is also possible to use a monochromatic color filter as the color filter 22, and in this case, the light shielding layer 23 can be omitted.

  The illustrated first birefringence layer 25 has a size and shape that overlaps the base material 21 in plan view. Therefore, the first birefringence layer 25 is larger than the display area in the display liquid crystal panel. When the optical element 30 having such a configuration is used as a constituent member of a liquid crystal alignment substrate, the heat resistance of the first birefringent layer 25 is relatively high, and therefore the first birefringent layer 25 is disposed in the liquid crystal cell. The display liquid crystal panel can be obtained, and the first birefringence layer 25 is easily prevented from being damaged in the process of manufacturing the liquid crystal display device. The first birefringence layer 25 can be used as a so-called “+ C plate”.

<Optical element (fourth embodiment)>
FIG. 4B is a schematic diagram showing still another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 35 shown in the figure can be used as, for example, a constituent member of a liquid crystal alignment substrate, and the first birefringence layer is provided only in the region DR corresponding to the display region in the display liquid crystal panel. This is different from the optical element 30 of the third embodiment described above (see FIG. 4A). Since the other configuration is the same as the configuration of the optical element 30 of the third embodiment, only the first birefringence layer is given a new reference sign “25A”, and components other than the first birefringence layer 25A are attached to the constituent members. Are denoted by the same reference numerals as those used in FIG.

  When this optical element 35 is a constituent member of a liquid crystal alignment substrate, the first birefringence layer 25A is a liquid crystal cell as in the case where the optical element 30 of the third embodiment is a constituent member of a liquid crystal alignment substrate. Since the display liquid crystal panel disposed inside can be obtained, it is easy to suppress damage to the first birefringence layer 25A in the process of manufacturing the liquid crystal display device. The first birefringence layer 25A can be used as a so-called “+ C plate”.

<Optical element (fifth embodiment)>
FIG. 4C is a schematic diagram showing still another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 50 shown in the figure can be used as, for example, a constituent member of a liquid crystal alignment substrate, and has a first birefringence layer 45R having a predetermined thickness on each micro color filter 22R, 22G, 22B. , 45G, or 45B is different from the optical element 30 of the third embodiment described above (see FIG. 4A) in that it is provided via the silicon oxide film 1b. A first birefringence layer 45R is formed on the micro color filter 22R via the silicon oxide film 1b, and a first birefringence layer 45G is formed on the micro color filter 22G via the silicon oxide film 1b. A first birefringence layer 45B is formed on the micro color filter 22B via a silicon oxide film 1b. Since the other configuration is the same as the configuration of the optical element 30 of the third embodiment, the same reference numerals as those used in FIG. 4A are used for the constituent members other than the first birefringence layers 45R, 45G, and 45B. The description is omitted.

  The refractive index of light varies depending on the wavelength even when incident on the same medium. Therefore, for example, the birefringence Δn of the first birefringence layer 5 shown in FIG. 1A also varies depending on the wavelength of incident light. By providing the first birefringence layers 45R, 45G, or 45B each having a predetermined film thickness on the micro color filters 22R, 22G, and 22B of the respective colors, the retardation of light of each color of red, green, and blue can be reduced. It can be controlled separately. Therefore, according to the optical element 50 of the present embodiment, the polarization state of light can be controlled more precisely than the optical element 30 of the third embodiment or the optical element 35 of the fourth embodiment. In forming each of the first birefringence layers 45R, 45G, and 45B at a predetermined location, for example, a photolithography method can be used.

  When this optical element 50 is used as a constituent member of a liquid crystal alignment substrate, the first birefringence layers 45R, 45R, 45C are formed as in the case where the liquid crystal alignment substrate is formed using the optical element 30 of the third embodiment. Since a liquid crystal panel for display in which 45B is disposed in the liquid crystal cell can be obtained, it is easy to suppress damage to the first birefringence layers 45R, 45G, and 45B in the process of manufacturing the liquid crystal display device. . Each of the first birefringence layers 45R, 45G, and 45B can be used as a so-called “+ C plate”.

<Optical element (6th form-8th form)>
FIG. 5A is a schematic view showing still another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 70 of the sixth embodiment shown in the figure can be used as a constituent member of a liquid crystal alignment substrate, for example, and has a first birefringence index on one surface of a glass substrate 61 as a light-transmitting base material. The layer 65 is formed, and the color filter 62 and the light-shielding layer (black matrix) 63 are formed on the first birefringence layer 65, so that the optical element 30 of the third embodiment described above (FIG. 4A). ))). Since the other configuration is the same as the configuration of the optical element 30 of the third embodiment, reference is made to each member constituting the optical element 70 by adding “40” to the numerical value portion of the reference symbol used in FIG. Reference numerals are assigned and explanations thereof are omitted. This optical element 70 has the same technical effect as the optical element 30 of the third embodiment.

  FIG. 5B is a schematic diagram showing still another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 75 of the seventh embodiment shown in the figure can be used as a constituent member of a liquid crystal alignment substrate, for example, and has a first birefringence index on one surface of a glass substrate 61 as a base material having optical transparency. The layer 65 is formed, and the color filter 62 and the light shielding layer (black matrix) 63 are formed on the first birefringence layer 65, so that the optical element 35 of the fourth embodiment described above (FIG. 4B). ))). Since the other configuration is the same as the configuration of the optical element 35 of the fourth embodiment, each member constituting the optical element 75 is obtained by adding “40” to the numerical value portion of the reference symbol used in FIG. Reference numerals are assigned and explanations thereof are omitted. The area corresponding to the display area in the display liquid crystal panel is indicated by the reference symbol DR as in FIG. This optical element 75 has the same technical effect as the optical element 35 of the fourth embodiment.

  FIG. 5C is a schematic view showing still another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 90 of the eighth embodiment shown in the figure can be used as a constituent member of a liquid crystal alignment substrate, for example, and has a predetermined film thickness on one surface of a glass substrate 61 as a light-transmitting substrate. The first birefringence layer 85R, 85G, 85B is formed, and the micro color filter 62R, 62G, or 62B is formed on the first birefringence layer 85R, 85G, 85B. Different from the optical element 50 (see FIG. 4C). Since the other configuration is the same as the configuration of the optical element 50 of the fifth embodiment, each member constituting the optical element 90 is obtained by adding “40” to the numerical part of the reference symbol used in FIG. Reference numerals are assigned and explanations thereof are omitted. This optical element 90 has the same technical effect as the optical element 50 of the fifth embodiment.

  In addition, in the optical elements 70, 75, and 90 of the sixth to eighth embodiments shown in FIGS. 5A to 5C, a resin substrate or a resin film can be used instead of the glass substrate 61. In that case, an inorganic material film such as a silicon oxide film is provided on the resin substrate or the resin film, and the first birefringence layers 65, 65A, 85R, 85G, and 85B are formed thereon. Is preferred.

<Optical element (9th form)>
FIG. 6 is a schematic view showing still another example of the basic cross-sectional structure of the optical element of the present invention. The optical element 110 shown in the figure can be used as, for example, a constituent member of a liquid crystal alignment substrate, and the third birefringence layer 25 is covered with a protective layer 100. Different from the optical element 30 (see FIG. 3A). Since the other configuration is the same as the configuration of the optical element 30 of the third embodiment, members other than the protective layer 100 constituting the optical element 110 are denoted by the same reference numerals as those used in FIG. Therefore, the description is omitted.

  The protective layer 100 is a layer for improving flatness, chemical resistance, heat resistance, ITO (indium tin oxide) resistance, and the like. The protective layer 100 can be formed of various photo-curing resins or thermosetting resins, such as acrylic resins, epoxy resins, polyimides, etc., or two-component curing resins. The protective layer 100 can be formed by a method such as spin coating, printing, or photolithography depending on the material. The film thickness of the protective layer 100 can be appropriately selected within the range of about 0.3 to 5.0 μm, and is preferably selected within the range of about 0.5 to 3.0 μm.

  Since the optical element 110 has the protective layer 100 in addition to the same technical effect as the optical element 30 of the third embodiment, it also has a technical effect that the reliability of the birefringence characteristics is improved. The protective layer 100 can be provided on each of the optical elements 10, 15, 35, 50, 70, 75, 90 of the first, second, and fourth to eighth embodiments already described, and will be described later. It can also be provided in the optical element of the eleventh form.

<Optical element (10th form)>
FIG. 7 is a schematic view showing still another example of the basic cross-sectional structure of the optical element of the present invention. An optical element 130 shown in the figure can be used as a constituent member of a liquid crystal alignment substrate, for example, and a linearly polarizing element 122 and a quarter wavelength plate 123 are arranged in this order on one side of a light transmitting substrate 121a. The silicon oxide film 1b, the first birefringence layer 125, and the second birefringence layer 128 are laminated in this order on the quarter-wave plate 123. The light transmissive substrate 121a, the linearly polarizing element 122, the quarter wavelength plate 123, and the silicon oxide film 1b constitute a light transmissive base material 121.

  In the liquid crystal alignment substrate including the optical element 130, the linearly polarizing element 122, the quarter wavelength plate 123, the silicon oxide film 1b, the first birefringence layer 125, and the second birefringence layer 128 are outside. The liquid crystal panel for display is arranged by being oriented. This liquid crystal alignment substrate is used as a substrate on the back side of a display liquid crystal panel in a transmissive liquid crystal display device, for example.

  The linearly polarizing element 122 functions as a polarizer in the display liquid crystal panel, and the quarter wavelength plate 123 is an optical element for converting circularly polarized light into linearly polarized light. The silicon oxide film 1b and the first birefringence layer 125 are configured in the same manner as the silicon oxide film 1b or the first birefringence layer 5 in the optical element 15 of the second form. The first birefringence layer 125 converts elliptically polarized light into circularly polarized light.

  The second birefringence layer 128 is a birefringence layer for extracting predetermined circularly polarized light from natural light. For example, the second birefringence layer 128 is formed of cholesteric liquid crystal in which the molecular arrangement is fixed by crosslinking. In obtaining the second birefringence layer 128, it is preferable to use a chiral nematic liquid crystal obtained by adding a chiral agent to a nematic liquid crystal. At this time, it is preferable to use a polymerizable chiral agent as the chiral agent. The second birefringence layer 128 has birefringence characteristics different from those of the first birefringence layer 125.

  When a liquid crystal alignment substrate including the optical element 130 is manufactured and a display liquid crystal panel is manufactured using the liquid crystal alignment substrate, the light utilization efficiency is increased and bright even if the illumination intensity of the backlight is low for the following reasons. Image display can be performed.

  That is, in order to increase the use efficiency of the radiated light from the backlight, it is desirable to increase the amount of circularly polarized light incident on the quarter-wave plate 123. It is desirable to extract (one of left circularly polarized light and right circularly polarized light) by the second birefringence layer 128. At this time, the other circularly polarized light cannot be incident on the second birefringence layer 128 and is reflected, but for example, if a mirror is disposed behind the backlight, the other one reflected by the second birefringence layer 128 is reflected. When the circularly polarized light is reflected by the mirror, the phase thereof is reversed to become the one circularly polarized light. Therefore, most of the emitted light from the backlight can be incident on the quarter-wave plate 123 as the one circularly polarized light.

  However, radiation light having a large incident angle to the second birefringence layer 128 is converted into elliptically polarized light by the second birefringence layer 128. This elliptically polarized light includes both left circularly polarized light and right circularly polarized light, and the one corresponding to the other circularly polarized light becomes elliptically polarized light without being converted into linearly polarized light by the quarter wavelength plate 123. Or is absorbed by the linearly polarizing element 122. By providing the first birefringence layer 125 between the second birefringence layer 128 and the quarter-wave plate 123, the light converted into elliptically polarized light by the second birefringence layer 128 is converted into circularly polarized light. can do. As a result, since the amount of circularly polarized light incident on the quarter-wave plate 123 increases, it is possible to increase the light utilization efficiency and perform bright image display even when the backlight illuminance is low.

  Further, when a liquid crystal alignment substrate including the optical element 130 is manufactured and a display liquid crystal panel is manufactured using the liquid crystal alignment substrate, the production cost of the first birefringence layer 125 can be easily reduced, and Since the birefringence characteristics of the first birefringence layer 125 are not easily affected by heat, it is easy to provide a liquid crystal display device that has high display characteristics and can be used for various purposes at low cost. .

  Note that the linear polarizing element 122, the quarter-wave plate 123, the silicon oxide film 1b, the first double-refractive-index layer 128 and the second birefringent layer 128 are reversed in the order shown in the drawing. It is also possible to dispose the refractive index layer 125 and the second birefringence layer 128 inside the display liquid crystal panel.

  Further, if the silicon oxide film 1b, the first birefringence layer 125, the quarter wavelength plate 123, and the linearly polarizing element 122 are laminated in this order on the light transmissive substrate 121a, the display in the reflective liquid crystal display device is performed. An optical element that can be used for a liquid crystal alignment substrate that is used as a substrate on the display surface side of the liquid crystal panel for use can be obtained. In this case, if the substrate 121 is made of glass or silicon oxide, the silicon oxide film 1b can be omitted. Similarly, the first birefringence layer 125 is formed on one surface of the light transmissive substrate 121a directly or via the silicon oxide film 1b, and the quarter wavelength plate 123 is formed on the other surface of the light transmissive substrate 121a. Even if the linearly polarizing elements 122 are laminated in this order, an optical element that can be used for a liquid crystal alignment substrate used as a substrate on the display surface side of a display liquid crystal panel in a reflective liquid crystal display device can be obtained. In the reflection type liquid crystal display device including these optical elements as a part of the liquid crystal alignment substrate, the polarization state of the light incident on the reflector can be brought close to true circularly polarized light, so that display with high contrast can be performed. It becomes easy.

<Optical element (11th form)>
FIG. 8 is a schematic view showing still another example of the basic cross-sectional structure of the optical element of the present invention. An optical element 150 shown in the figure can be used as, for example, a constituent member of a liquid crystal alignment substrate. A horizontal alignment film 149, a second birefringence layer 148, a silicon oxide are formed on one surface of a light transmitting substrate 141a. The film 141 b and the first birefringence layer 145 are laminated in this order, and the color filter 142 and the light shielding layer (black matrix) 143 are formed on the first birefringence layer 145. The light transmissive substrate 141a, the horizontal alignment film 149, the second birefringence layer 148, and the silicon oxide film 141b constitute a light transmissive base material 141.

  The light transmissive substrate 141a and the silicon oxide film 141b are configured in the same manner as the light transmissive substrate 1 or the silicon oxide film 1b in the optical element 15 of the third embodiment shown in FIG. The horizontal alignment film 149 can horizontally align the liquid crystal, and can be obtained, for example, by subjecting the surface of a film formed of a resin material to rubbing treatment or photo-alignment treatment. The second birefringence layer 148 is made of, for example, a polymer in which a polymerizable liquid crystal is fixed in a homogeneous alignment state, and is optically uniaxial and has a birefringence layer (so-called “+ A plate”) whose optical axis is in the plane. ). The second birefringence layer 148 has birefringence characteristics different from those of the first birefringence layer 145.

  Since the color filter 142 and the light shielding layer 143 are configured in the same manner as the color filter 62 or the light shielding layer 63 in the optical element 70 of the sixth embodiment shown in FIG. 5A, they are used in FIG. A reference numeral obtained by adding “80” to the numerical part of the reference numeral will be attached and description thereof will be omitted.

  The liquid crystal alignment substrate using the optical element 150 is arranged such that the horizontal alignment film 149, the second birefringence layer 148, the silicon oxide film 141b, and the first birefringence layer 145 are inward. A liquid crystal panel for display is configured. This substrate for liquid crystal alignment is used as a substrate on the display surface side in a display liquid crystal panel.

  Since the liquid crystal alignment substrate including the optical element 150 has the first birefringence layer 145 and the second birefringence layer 148, it forms an angle of 45 ° or 135 ° with the slow axis of the analyzer. The viewing angle characteristics in the azimuth direction can be improved.

  Further, when a display liquid crystal panel is manufactured using a liquid crystal alignment substrate including the optical element 150, the production cost of the first birefringence layer 145 can be easily reduced, and the first birefringence layer 145 can be reduced. Since the birefringence characteristics are not easily affected by heat, it is easy to provide a liquid crystal display device that has high display characteristics and can be used for various purposes at low cost.

  As the second birefringence layer 148, a + A plate made of a stretched resin film can also be used. In this case, the horizontal alignment film 149 is omitted. The + A plate made of a stretched resin film is stuck on the light transmissive substrate 141a with an adhesive.

  Further, the color filter 142 and the light shielding layer 143 are formed on the second birefringence layer 148, the silicon oxide film 141b is formed so as to cover the color filter 142 and the light shielding layer 143, and the first birefringence layer 148 is formed thereon. A refractive index layer 145 can also be provided. Furthermore, the color filter 142, the light shielding layer 143, the silicon oxide film 141b, and the first birefringence layer 145 are formed on one side of the light transmissive substrate 141a, and the surface of the substrate 141 opposite to the one side is formed. It is also possible to provide the second birefringence layer 148.

<Optical element manufacturing method>
The method for producing an optical element of the present invention is the above-described method for producing an optical element of the present invention, and this method includes a preparation process, an alignment process, and a crosslinking process, as described above. Hereinafter, these steps will be described in detail.

(1) Preparation process;
In the preparation step, a light-transmitting base material is prepared. The base material may have a single-layer structure or a multi-layer structure. When making a base material into a single layer structure, it is preferable to form this base material by glass or a silicon oxide. When the base material has a multi-layer structure, the structure can be appropriately selected according to the use of the optical element to be manufactured, and even in this case, the layer serving as the base of the first birefringence layer is glass or It is preferable to form with silicon oxide.

  The substrate is preferably optically isotropic, but a light-shielding region or the like can be locally provided as necessary. The light transmittance of the substrate can be appropriately selected according to the use of the optical element to be manufactured. The substrate may be produced by itself, or may be purchased by another person or another manufacturer.

(2) orientation step;
In the alignment step, a polymerizable liquid crystal having a rod-like molecular shape, a coupling agent capable of homeotropic alignment of the polymerizable liquid crystal, and a surfactant capable of homeotropic alignment of the polymerizable liquid crystal, Is formed, and the polymerizable liquid crystal in the coating film is homeotropically aligned.

  In preparing the above coating composition, a polyfunctional polymerizable liquid crystal, the above coupling agent, the above surfactant and an organic solvent are used as essential components. Agents, sensitizers, etc. are used as optional components. Only one type of monofunctional polymerizable liquid crystal may be used, or two or more types may be used in combination. Similarly, only one type of photopolymerization initiator and sensitizer may be used, or two or more types may be used in combination. Since the above-mentioned polymerizable liquid crystal, coupling agent, and surfactant have already been described in the description of the first embodiment according to the optical element of the present invention, they are omitted here.

  The organic solvent should just be a thing which can melt | dissolve a polymeric liquid crystal, The kind can be selected suitably. Examples of the optional photopolymerization initiator include benzyl (or bibenzoyl), benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, benzoyl methyl benzoate, 4-benzoyl-4 ′ methyl diphenyl sulfide, Benzylmethyl ketal, dimethylaminomethylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3′-dimethyl-4-methoxybenzophenone, methylobenzoylformate, 2- Methyl-1- (4- (methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4 Dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl)- 2-hydroxy-2-methylpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 1-chloro-4-propoxythio Sandton and the like can be mentioned. Sensitizers can be added as appropriate as long as the object of the present invention is not impaired.

  The concentration of the polymerizable liquid crystal in the coating composition varies depending on the coating method, the film thickness of the coating film to be formed, the type of the organic solvent, etc., but is preferably in the range of 10 to 50% by weight. The concentration of the coupling agent is preferably about 0.001 to 10% by weight, more preferably about 0.01 to 1% by weight, based on the total amount of the polymerizable liquid crystal. The concentration of the surfactant can be appropriately selected within the range of about 1/100 to 1/1 of the solid content of the coupling agent.

  When a photopolymerization initiator is used, the concentration of the photopolymerization initiator in the coating composition can be appropriately selected within a range that does not significantly impair the orientation of the polymerizable liquid crystal, for example, within a range of about 0.01 to 10% by weight. Selected. The concentration of the photopolymerization initiator is preferably selected within a range of about 0.1 to 7% by weight, and more preferably selected within a range of about 0.5 to 5% by weight. When a sensitizer is used, the concentration of the sensitizer in the coating composition can be appropriately selected within a range that does not significantly impair the orientation of the polymerizable liquid crystal, and is selected within a range of, for example, about 0.01 to 1% by weight. The

  The coating film by the coating composition described above is formed by applying this coating composition on a substrate by a method such as spin coating or various printing methods (for example, die coating, bar coating, slide coating, roll coating, etc.). can do. Polymeric liquid crystals can be homeotropically aligned when the substrate surface has high water or oil repellency, or when the coupling agent or surfactant added to the coating composition has strong water or oil repellency. Within such a range, the wettability of the surface (application surface) may be increased in advance by UV cleaning or plasma treatment.

  In the homeotropic alignment of the polymerizable liquid crystal in the coating film formed as described above, the temperature is higher than the temperature at which the polymerizable liquid crystal in the coating film becomes a liquid crystal phase and less than the temperature at which it becomes an isotropic phase (liquid phase). (Hereinafter, this temperature is referred to as “first crosslinking temperature”). The phase transition temperature of the polymerizable liquid crystal in the coating film may be different from the phase transition temperature of the polymerizable liquid crystal alone since the coupling agent and the surfactant are contained in the coating film. When the polymerizable liquid crystal becomes a liquid crystal phase, the polymerizable liquid crystal is homeotropically aligned by the action of the coupling agent.

  For example, when the coating film is dried under reduced pressure, the polymerizable liquid crystal originally exhibits the liquid crystal phase. For example, by drying the coating film under reduced pressure, the polymerizable liquid crystal can be homeotropically aligned and brought into a supercooled state. In addition, it is possible to cool the supercooled polymerizable liquid crystal to, for example, room temperature while maintaining homeotropic alignment.

(3) cross-linking step;
In the cross-linking step, the polymerizable liquid crystal is three-dimensionally cross-linked while keeping the polymerizable liquid crystal in the coating film homeotropically aligned. At this time, in order to prevent the homeotropic alignment of the polymerizable liquid crystal from being disturbed, the light having a photosensitive wavelength of the polymerizable liquid crystal is irradiated while heating the coating film to the first crosslinking temperature in an inert gas atmosphere. Is preferably irradiated. Alternatively, after the coating film is heated to the first crosslinking temperature in an air atmosphere, the coating liquid is irradiated with light having a photosensitive wavelength of the polymerizable liquid crystal to partially advance the crosslinking reaction, and then the polymerizable liquid crystal is crystallized. It is preferable to cool the coating film to an air temperature in the air atmosphere, and in this state, irradiate the coating film with light having the photosensitive wavelength to substantially complete the crosslinking reaction. The “temperature at which the polymerizable liquid crystal becomes a crystalline phase” means the temperature at which the polymerizable liquid crystal becomes a crystalline phase in the coating film before crosslinking.

  Since the photosensitive wavelength of the polymerizable liquid crystal varies depending on the type of the polymerizable liquid crystal, the wavelength of the light to be irradiated is appropriately selected according to the type of the polymerizable liquid crystal contained in the coating film. The light applied to the coating film does not need to be monochromatic light, and can be irradiated with light in a wavelength region including light having a photosensitive wavelength of the polymerizable liquid crystal.

  By performing up to this crosslinking step, an optical element having a light-transmitting base material and a first birefringence layer formed on the base material, wherein the first birefringence layer is It consists of a cross-linked polymer that contains a coupling agent and a surfactant capable of homeotropic alignment of a rod-shaped polymerizable liquid crystal, and this cross-linked polymer is a homeotropic compound of a rod-shaped polymerizable liquid crystal. An optical element having a three-dimensionally cross-linked structure while maintaining the orientation state can be obtained.

<Liquid crystal alignment substrate (first embodiment)>
FIG. 9A is a schematic view showing an example of a basic cross-sectional structure of the liquid crystal alignment substrate of the present invention. The liquid crystal alignment substrate 210 shown in the figure has a structure in which a horizontal alignment film 205 is provided on the protective layer 100 in the optical element 110 according to the ninth embodiment shown in FIG. Among the structural members, the structural members already shown in FIG. 6 are denoted by the same reference numerals as those used in FIG.

  In the illustrated liquid crystal alignment substrate 210, the protective layer 100 functions as a planarizing film for the horizontal alignment film 205. The horizontal alignment film 205 is for horizontally aligning the liquid crystal in the liquid crystal cell when a liquid crystal panel for display is manufactured using the liquid crystal alignment substrate 210, and the surface (upper surface) thereof is subjected to, for example, rubbing treatment. Or photo-alignment treatment.

  The liquid crystal alignment substrate 210 having such a structure can be used, for example, as a substrate on the display surface side of a display liquid crystal panel in an IPS liquid crystal display device. Since the first birefringence layer 25 is provided, for example, the optical axis is optically uniaxial on the outer surface of the substrate 1 (meaning the outer surface when a liquid crystal panel for display is formed). By providing an in-plane retardation plate or retardation film (so-called “+ A plate”), the slow axis of the analyzer (not shown) constituting the liquid crystal panel for display is 45 ° or 135 °. The viewing angle characteristic in the azimuth direction that forms an angle can be improved.

  As already explained, the production cost of the first birefringent layer 25 is easy to suppress. Further, the heat resistance of the first birefringence layer 25 is relatively high. Therefore, by using the liquid crystal alignment substrate 210, a liquid crystal display device having excellent viewing angle characteristics and relatively high heat resistance can be obtained at low cost. In addition, it is easy to provide a liquid crystal display device that has high display characteristics and can be used for various purposes at low cost.

  The protective film 100 can be omitted. Further, in place of the optical element 110, the optical element 35 of the fourth form shown in FIG. 3B, the optical element 50 of the fifth form shown in FIG. 3C, and the optical element 50 shown in FIG. It is also possible to use the six-form optical element 70, the seventh-form optical element 75 shown in FIG. 4B, or the eighth-form optical element 90 shown in FIG.

<Liquid crystal alignment substrate (second embodiment)>
FIG. 9B is a schematic view showing another example of the basic cross-sectional structure of the liquid crystal alignment substrate of the present invention. The liquid crystal alignment substrate 230 shown in the figure has a structure in which a planarizing film 222 is provided on the optical element 150 of the eleventh form shown in FIG. 8, and a horizontal alignment film 225 is further provided thereon. Of the constituent members of the liquid crystal alignment substrate 230, the constituent members already shown in FIG. 8 are denoted by the same reference numerals as those used in FIG.

  In the illustrated liquid crystal alignment substrate 230, a planarizing film 222 is provided so as to cover the color filter 142 and the light shielding layer 143. The planarizing film 222 can be formed, for example, in the same manner as the protective layer 100 in the liquid crystal alignment substrate 210 of the first form. The horizontal alignment film 225 in the liquid crystal alignment substrate 230 can also be formed in the same manner as the horizontal alignment film 205 in the liquid crystal alignment substrate 210 of the first embodiment.

  Similarly to the liquid crystal alignment substrate 210 of the first embodiment, the liquid crystal alignment substrate 230 of this embodiment can be used as a substrate on the display surface side of a display liquid crystal panel in an IPS liquid crystal display device, for example. Since the liquid crystal alignment substrate 230 has the second birefringence layer 148, an analyzer (FIG. 5) is formed without providing a + A plate on the outer surface of the liquid crystal alignment substrate 230. The viewing angle characteristics in the azimuth direction that forms an angle of 45 ° or 135 ° with the slow axis of (not shown)) can be improved. Note that the planarization film 222 can be omitted.

<Liquid crystal alignment substrate (third embodiment)>
FIG. 10A is a schematic view showing still another example of the basic cross-sectional structure of the liquid crystal alignment substrate of the present invention. The liquid crystal alignment substrate 260 shown in the figure includes a scanning line, an interlayer insulating film 241 and a large number of pixel electrodes 243a arranged in a matrix on the base material 121 in the optical element 130 of the tenth embodiment shown in FIG. The transparent electrode pattern 243, the signal line 245, the protective film (passivation film) 247, the switching circuit portion, the planarization film 249, and the alignment film 251 are provided. Among the constituent members of the liquid crystal alignment substrate 260, those already shown in FIG. 7 are assigned the same reference numerals as those used in FIG.

  Although the scanning lines do not appear in FIG. 10A, they are arranged so as to correspond to one row of a large number of pixel electrodes 243a arranged in a matrix, and in the longitudinal direction of the row. It extends. Each scanning line can be formed of a metal such as tantalum (Ta) or titanium (Ti). These scanning lines are covered with an interlayer insulating film 241.

  The interlayer insulating film 241 is formed of an electrically insulating material such as silicon oxide, for example, and electrically separates the scanning lines and the signal lines 245 and electrically separates the pixel electrodes 243a and the scanning lines. is doing.

  Each pixel electrode 243a is formed of a transparent electrode material such as indium tin oxide (ITO), for example, so as to correspond to each pixel in the display liquid crystal panel. The shape of each pixel electrode 243a in plan view can be, for example, a polygon such as a quadrangle or a hexagon formed by cutting one corner of the quadrangle into a rectangle.

  The signal lines 245 are arranged so as to correspond to one column of a large number of pixel electrodes 243a arranged in a matrix, and extend in the longitudinal direction of the column. Each signal line 245 can be formed of a metal such as tantalum (Ta) or titanium (Ti). These signal lines 245 are covered with a protective film 247.

  The protective film 247 is formed of, for example, silicon nitride and protects the underlying member. Further, the signal line 245 and the pixel electrode 243a are electrically separated.

  Although the switching circuit portion does not appear in FIG. 10A, the switching circuit portion is arranged corresponding to one pixel electrode 243a one by one, the pixel electrode 243a corresponding to the switching circuit portion, the scanning line and the signal line. H.245 is electrically connected. Each switching circuit unit receives a signal from a corresponding scanning line and controls conduction between the signal line 245 and the pixel electrode 243a. Each switching circuit unit can be configured using, for example, one active element. As the active element, for example, a three-terminal element such as a thin film transistor or a two-terminal element such as an MIM (Metal Insulator Metal) diode is used.

  The planarization film 249 is formed so as to cover the protective film 247 and the transparent electrode pattern 243, and provides a flat surface for forming the alignment film 251. The planarizing film 249 can be formed, for example, in the same manner as the protective layer 100 in the liquid crystal alignment substrate 210 of the first form.

  The alignment film 251 is a horizontal alignment film for horizontally aligning the liquid crystal in the liquid crystal cell when a liquid crystal panel for display is manufactured using the liquid crystal alignment substrate 260, or a vertical alignment for vertically aligning the liquid crystal. It is an alignment film. Which of the horizontal alignment film and the vertical alignment film is used as the alignment film 251 can be appropriately selected according to the operation mode of the display liquid crystal panel to be manufactured using the liquid crystal alignment substrate 260.

  The liquid crystal alignment substrate 260 having such a structure can be used, for example, as a substrate on the back side of a display liquid crystal panel in an active matrix drive type transmissive liquid crystal display device. Since the first birefringence layer 125 and the second birefringence layer 128 are formed on the liquid crystal alignment substrate 260, a transmissive liquid crystal display device with high light utilization efficiency can be obtained by using the liquid crystal alignment substrate 260. Can do. Further, since the liquid crystal alignment substrate 260 has the first birefringence layer 125, a transmissive liquid crystal display device having relatively high heat resistance can be obtained at low cost by using the liquid crystal alignment substrate 260. In addition, it becomes easy to inexpensively provide a transmissive liquid crystal display device that has high display characteristics and can be used for various purposes. Note that the planarization film 249 can be omitted.

<Liquid crystal alignment substrate (fourth embodiment)>
FIG. 10B is a schematic view showing still another example of the basic cross-sectional structure of the liquid crystal alignment substrate of the present invention. The liquid crystal alignment substrate 280 shown in the figure is provided with a color filter 272 and a light shielding layer (black matrix) 273 on the base 121 in the optical element 130 of the tenth embodiment shown in FIG. A planarization film 275 is formed so as to cover the light shielding layer 273, and a transparent electrode pattern 277 and an alignment film 279 are stacked in this order on the planarization film 275. The color filter 272, the light shielding layer 273, the flattening film 275, the transparent electrode pattern 277, and the alignment film 279 are all surfaces on the opposite side to the surface on which the linearly polarizing element 122 is provided on the substrate 121. Is provided.

  Among the constituent members of the liquid crystal alignment substrate 280, the constituent members already shown in FIG. 7 are denoted by the same reference numerals as those used in FIG. Further, the color filter 272 and the light shielding layer 273 can be configured in the same manner as the color filter 22 or the light shielding layer 23 in the optical element 30 of the third embodiment shown in FIG. About the filter and the light shielding layer, the reference numeral obtained by adding “250” to the numerical part of the reference numeral used in FIG.

  The planarization film 275 is formed so as to cover the color filter 272 and the light shielding layer 273 and provides a flat surface for forming the transparent electrode pattern 277. The planarizing film 275 can be formed, for example, in the same manner as the protective layer 100 in the liquid crystal alignment substrate 210 of the first form.

  The transparent electrode pattern 277 is applied with a voltage for controlling the alignment of the liquid crystal in the display liquid crystal panel using the liquid crystal alignment substrate 280. For example, the transparent electrode pattern 277 is formed of a transparent electrode material such as ITO. It is used as an electrode (common electrode) common to all pixels in the liquid crystal panel.

  The alignment film 279 is a horizontal alignment film for horizontally aligning liquid crystals in a liquid crystal cell when a liquid crystal panel for display is manufactured using the liquid crystal alignment substrate 280, or a vertical alignment for vertically aligning the liquid crystals. It is an alignment film. Which of the horizontal alignment film and the vertical alignment film is used as the alignment film 279 can be appropriately selected according to the operation mode of the display liquid crystal panel to be manufactured using the liquid crystal alignment substrate 280.

  The liquid crystal alignment substrate 280 having such a structure can be used, for example, as a substrate on the display surface side of a display liquid crystal panel in a reflective liquid crystal display device. Since the first birefringence layer 125 and the second birefringence layer 128 are formed on the liquid crystal alignment substrate 280, a reflection type liquid crystal display device with high light utilization efficiency can be obtained by using the liquid crystal alignment substrate 280. Can do. In addition, since the liquid crystal alignment substrate 280 has the first birefringence layer 125, a reflective liquid crystal display device having relatively high heat resistance can be obtained at low cost by using the liquid crystal alignment substrate 280. In addition, it becomes easy to inexpensively provide a reflective liquid crystal display device that has high display characteristics and can be used for various purposes. Note that the planarization film 249 can be omitted.

<Liquid crystal display device (first form)>
FIG. 11 is a partial sectional view schematically showing an example of the liquid crystal display device of the present invention. The illustrated liquid crystal display device 400 includes an IPS-type transmissive liquid crystal display including a display liquid crystal panel 300, a backlight unit 380 installed behind the display liquid crystal panel 300, and an external circuit (not shown). Device.

  The display liquid crystal panel 300 includes the liquid crystal alignment substrate 210 of the first embodiment described above as a display surface side substrate (first liquid crystal alignment substrate), and a back surface side substrate (second liquid crystal alignment substrate). A liquid crystal alignment substrate 350 is provided.

  The liquid crystal alignment substrate 350 includes a light-transmitting substrate 305, a large number of counter electrodes 310 arranged in a predetermined pattern on one surface of the light-transmitting substrate 305, an interlayer insulating film 315 covering these counter electrodes 310, and a display liquid crystal. The pixel electrode 320 formed on the interlayer insulating film 315, the protective layer 325 covering the interlayer insulating film 315 and each pixel electrode 320, and the protective layer 325 are formed so as to correspond to one pixel in the panel 300 one by one. The horizontal alignment film 330 is provided.

  The counter electrodes 310 are arranged separately on both sides of the corresponding pixel column so as to correspond to each pixel column in the display liquid crystal panel 300 two by two. These counter electrodes 310 can be formed of a metal such as tantalum (Ta) or titanium (Ti). Each pixel electrode 320 is formed of a transparent electrode material such as ITO, for example, and vertically cuts substantially the center of the corresponding pixel in plan view. The protective layer 325 can be formed in the same manner as the protective layer 100 in the liquid crystal alignment substrate 210 of the first embodiment shown in FIG. 9A, for example. For example, the horizontal alignment film 330 can be formed in the same manner as the horizontal alignment film 205 in the liquid crystal alignment substrate 210 of the first embodiment.

  Although not shown in FIG. 11, gate wiring (scanning line) and drain wiring arranged on the liquid crystal alignment substrate 350 so as to correspond to one pixel row in the display liquid crystal panel 300 one by one. And a storage capacitor line, and a switching circuit portion arranged so as to correspond to each pixel one by one. Each switching circuit unit includes a plurality of switching elements (for example, thin film transistors, MIM diodes, etc.).

  The liquid crystal alignment substrate 350 having the above-described structure and the above-described liquid crystal alignment substrate 210 are arranged such that the horizontal alignment film 205 in the liquid crystal alignment substrate 210 and the horizontal alignment film 330 in the liquid crystal alignment substrate 350 face each other. It is bonded with a sealant (thermosetting resin) 360 with a gap. The interval (cell gap) between the liquid crystal alignment substrates 210 and 350 is kept constant by a spacer (not shown) (for example, a spherical spacer or a columnar spacer), and the gap between the two is filled with a liquid crystal material. Thus, a liquid crystal layer 370 is formed.

  Further, a retardation film (so-called “+ A plate”) 372 that is optically uniaxial and has an in-plane optical axis is attached to the outer surface of the liquid crystal alignment substrate 210, and an analyzer is provided thereon. 374 is affixed. On the other hand, a polarizer 376 is attached to the outer surface of the liquid crystal alignment substrate 350. The analyzer 374 and the polarizer 376 can be arranged so as to have a crossed Nicols relationship or can be arranged so as to have a parallel Nicols relationship. The backlight unit 380 is disposed behind the polarizer 376.

  In the liquid crystal display device 400 having such a configuration, the first birefringence layer 25 is formed on the liquid crystal alignment substrate 210 and the retardation film 372 is attached to the outer surface of the liquid crystal alignment substrate 210. The viewing angle characteristics can be easily improved. In addition, since the heat resistance of the first birefringence layer 25 is relatively high, the liquid crystal display device 400 can be used as a liquid crystal display device for indoor use. It can also be used as a liquid crystal display device. Further, since the production cost of the first birefringence layer 25 can be easily reduced, the liquid crystal display device 400 can be provided at a low cost. Instead of the liquid crystal alignment substrate 210, the liquid crystal alignment substrate 230 of the second embodiment shown in FIG. 9B can be used.

<Liquid crystal display device (second embodiment)>
FIG. 12 is a partial sectional view schematically showing another example of the liquid crystal display device of the present invention. The illustrated liquid crystal display device 600 includes a display liquid crystal panel 500, a backlight unit 580 installed behind the display liquid crystal panel 500, and an active matrix drive transmission type that includes an external circuit (not shown). It is a liquid crystal display device.

  The display liquid crystal panel 500 includes a liquid crystal alignment substrate 260 of the third form shown in FIG. 10A as a back side substrate (second liquid crystal alignment substrate), and a display side substrate (first liquid crystal alignment substrate). A liquid crystal alignment substrate 550 is provided as a liquid crystal alignment substrate). The liquid crystal alignment substrate 550 includes the linearly polarizing element 122, the quarter wavelength plate 123, the silicon oxide film 1b, the first birefringence layer 125, the liquid crystal alignment substrate 280 of the fourth embodiment shown in FIG. And the second birefringence layer 128 is excluded.

  The liquid crystal alignment substrate 550 and the liquid crystal alignment substrate 260 are formed of a sealing material (with a gap therebetween such that the alignment film 279 in the liquid crystal alignment substrate 550 and the alignment film 251 in the liquid crystal alignment substrate 260 face each other. (Thermosetting resin) 560. As the alignment film 279, either a horizontal alignment film or a vertical alignment film can be used. However, when a horizontal alignment film is provided as the alignment film 279, the horizontal alignment film is also used as the alignment film 251. When a vertical alignment film is provided, a vertical alignment film is also used as the alignment film 251.

  The distance (cell gap) between the liquid crystal alignment substrates 550 and 260 is kept constant by a spacer (not shown) (for example, a spherical spacer or a columnar spacer), and the gap between them is filled with a liquid crystal material. A liquid crystal layer 570 is formed. An analyzer 575 is attached to the outer surface of the liquid crystal alignment substrate 550. The analyzer 575 and the linearly polarizing element 122 in the liquid crystal alignment substrate 260 can be arranged so as to have a crossed Nicols relationship or can be arranged so as to have a parallel Nicols relationship. The backlight unit 580 is disposed behind the liquid crystal alignment substrate 260.

  In the liquid crystal display device 600 having such a configuration, since the first birefringence layer 125 and the second birefringence layer 128 are formed on the liquid crystal alignment substrate 260, the emitted light from the backlight unit 580 Utilization efficiency can be easily increased. In addition, since the heat resistance of the first birefringence layer 125 is relatively high, the liquid crystal display device 600 can be used as a liquid crystal display device for indoor use, as well as for in-vehicle use that is exposed to a relatively high temperature environment. It can also be used as a liquid crystal display device. Further, since the production cost of the first birefringence layer 125 can be easily reduced, the liquid crystal display device 600 can be provided at a low cost.

<Example 1; Production of optical element>
(Preparation process)
A non-alkali glass substrate having a thickness of 0.7 mm and a non-alkali glass substrate having a thickness of 0.7 mm (NA35 manufactured by NH Techno Glass) was prepared as a substrate having optical transparency.

(Orientation process)
First, TSL8233, a silicone manufactured by Toshiba Silicone Co., Ltd., TSL8114 (both trade names) manufactured by Toshiba Silicone, and 0.005N hydrochloric acid were mixed at a ratio of 10: 3: 4.7 (mass ratio). Was hydrolyzed to obtain a silane coupling agent.

  Next, 25 parts by weight of the polyfunctional polymerizable liquid crystal represented by the formula (IV) shown in FIG. A liquid crystal solution was obtained, and this polymerizable liquid crystal solution was mixed with a solution obtained by diluting the silane coupling agent with isopropyl alcohol to 10 wt% at a ratio of 99.25: 0.75 (mass ratio). A predetermined amount of octadecyldimethyl (3-trimethoxysilylpropyl) ammonium chloride was added to the mixed solution to prepare a coating composition for forming a first birefringence layer. At this time, Irg907 (trade name) manufactured by Ciba Specialty Chemicals was used as a photopolymerization initiator. The amount of octadecyldimethyl (3-trimethoxysilylpropyl) ammonium chloride added was 1/10 by mass ratio with respect to the total amount of TSL8233 and TSL8114.

  Next, the coating composition for forming the first birefringence layer was spin-coated on the glass substrate to form a coating film, and the coating film was heated to 80 ° C. The coating film changed from a cloudy state to a transparent state as it was heated. From this, it was confirmed that the polymerizable liquid crystal in the coating film changed from the crystal phase to the liquid crystal phase by heating.

(Crosslinking process)
While the coating film in which the polymerizable liquid crystal had undergone phase transition was heated to 80 ° C., this coating film was irradiated with ultraviolet rays in a nitrogen gas atmosphere to cross-link the polymerizable liquid crystal in the coating film three-dimensionally. At this time, ultraviolet irradiation was performed under the conditions of irradiation intensity of 30 mW / cm ² and irradiation time of 1 minute using an ultraviolet irradiation apparatus equipped with an ultrahigh pressure mercury lamp as a light source.

  By performing the above-described crosslinking step, the first compound containing the above-mentioned silane coupling agent as a coupling agent having a structure in which the polymerizable liquid crystal represented by the formula (IV) has a three-dimensionally crosslinked structure. A refractive index layer was formed, and the target optical element was obtained. When the film thickness of the first birefringence layer in this optical element was measured with a stylus type step meter, it was about 1.8 μm.

(Evaluation)
When the retardation in the thickness direction of the obtained optical element was measured in the same manner as in Example 1, it was almost 0 nm (strictly 3 nm). When the optical element is covered in any direction from this direction with reference to the thickness direction when the optical element is horizontally disposed, the retardation increases. From these, it was confirmed that the polymerizable liquid crystal is homeotropically aligned in the first birefringence layer.

  Further, even when the optical element was heated to 200 ° C., the first birefringent layer maintained a transparent state without causing a phase transition. From this, it is judged that the first birefringence layer has a structure in which the polymerizable liquid crystal is three-dimensionally crosslinked.

<Example 2; Production of optical element>
In preparing the coating composition for forming the first birefringence layer, instead of octadecyldimethyl (3-trimethoxysilylpropyl) ammonium chloride, Drypon 600E (trade name of a surfactant manufactured by Nikka Chemical Co., Ltd.) was used. And the ratio of the said dry pon 600E with respect to the total amount of TSL8233 used as a raw material of a silane coupling agent and TSL8114 (above) was 1/20 in mass ratio. Otherwise, the preparation step, the alignment step, and the crosslinking step were sequentially performed under the same conditions as in Example 1 to obtain an optical element having a first birefringence layer having a thickness of 2.5 μm.

  When the retardation in the thickness direction of this optical element was measured in the same manner as in Example 1, it was almost 0 nm (strictly 1 nm). When the optical element is covered in any direction from this direction with reference to the thickness direction when the optical element is horizontally disposed, the retardation increases. From these, it was confirmed that the polymerizable liquid crystal is homeotropically aligned in the first birefringence layer.

  Further, even when the optical element was heated to 200 ° C., the first birefringent layer maintained a transparent state without causing a phase transition. From this, it is judged that the first birefringence layer has a structure in which the polymerizable liquid crystal is three-dimensionally crosslinked.

FIG. 1A is a schematic diagram showing an example of a basic cross-sectional structure of the optical element of the present invention, and FIG. 1B shows the structure of the first birefringence layer shown in FIG. It is sectional drawing which shows this typically. 2 (a) to 2 (f) are expressions representing the polyfunctional polymerizable liquid crystal, respectively, and FIGS. 2 (g) to 2 (j) are expressions representing the monofunctional polymerizable liquid crystal, respectively. is there. It is the schematic which shows the other example of the basic cross-section of the optical element of this invention. FIG. 4A to FIG. 4C are schematic views showing still other examples of the basic cross-sectional structure of the optical element of the present invention. FIG. 5A to FIG. 5C are schematic views showing still other examples of the basic cross-sectional structure of the optical element of the present invention. It is the schematic which shows the further another example of the basic cross-section of the optical element of this invention. It is the schematic which shows the further another example of the basic cross-section of the optical element of this invention. It is the schematic which shows the further another example of the basic cross-section of the optical element of this invention. FIG. 9A is a schematic diagram showing an example of the basic cross-sectional structure of the liquid crystal alignment substrate of the present invention, and FIG. 9B is the basic cross-sectional structure of the liquid crystal alignment substrate of the present invention. It is the schematic which shows another example. FIG. 10A to FIG. 10B are schematic views showing still other examples of the basic cross-sectional structure of the liquid crystal alignment substrate of the present invention. It is a fragmentary sectional view showing roughly an example of a liquid crystal display device of the present invention. It is a fragmentary sectional view which shows schematically the other example of the liquid crystal display device of this invention.

Explanation of symbols

1, 21, 61, 121, 141 Light-transmitting substrate 1b, 141b Silicon oxide film 5, 25, 45R, 45G, 45B, 65, 65A First birefringence layer 6 Polymerizable liquid crystal as structural unit Molecule 10, 15, 30, 35, 50, 70, 75, 90 Optical element 22, 62, 142 Light absorption type color filter 85R, 85G, 85B, 125, 145 First birefringence layer 110, 130, 150 Optical element 128, 148 Second birefringence layer 205, 225, 251, 279 Alignment film 210, 230, 260, 280 Liquid crystal alignment substrate 210, 550 First liquid crystal alignment substrate 260, 350 Second liquid crystal alignment substrate 400 600 Liquid crystal display device

Claims (15)

An optical element having a light-transmitting substrate and a first birefringence layer formed on the substrate,
The first birefringence layer is made of a crosslinked polymer containing a coupling agent and a surfactant capable of homeotropic alignment of a rod-like polymerizable liquid crystal.
An optical element, wherein the crosslinked polymer has a structure in which a polymerizable liquid crystal having a rod-like molecular shape is three-dimensionally crosslinked while maintaining a homeotropic alignment state.   The optical element according to claim 1, wherein the base material is a glass substrate.   The optical element according to claim 1, wherein the base material has a silicon oxide film, and the first birefringence layer is formed on the silicon oxide film.   The tilt angle of polymerizable liquid crystal molecules as a structural unit in the first birefringence layer is substantially uniform in the thickness direction of the first birefringence layer. The optical element according to any one of the above. 5. The optical element according to claim 1, wherein a light absorption color filter is formed on the light-transmitting substrate. The optical element according to claim 5, wherein the light absorption color filter is directly formed on the light-transmitting base material or the first birefringence layer. Furthermore, the 2nd birefringence layer which has a birefringence characteristic different from the said 1st birefringence layer is formed on the base material which has the said light transmittance , The any one of Claims 1-4 characterized by the above-mentioned. 2. The optical element according to item 1. The optical element according to claim 7, further comprising a light absorption type color filter, wherein the light absorption type color filter is directly formed on the second birefringence layer. The second birefringence layer is formed directly on the light-transmitting base material, on a horizontal alignment film provided on the base material, or on the first birefringence layer. The optical element according to claim 7. A method for manufacturing an optical element according to any one of claims 1 to 9 ,
A preparation step of preparing a substrate having light permeability;
A polymerizable liquid crystal having a rod-like molecular shape on the substrate, a coupling agent capable of homeotropic alignment of the polymerizable liquid crystal, and a surfactant capable of homeotropic alignment of the polymerizable liquid crystal. An alignment step of forming a coating film of the coating composition containing, and homeotropic alignment of the polymerizable liquid crystal in the coating film;
A cross-linking step of three-dimensionally cross-linking the polymerizable liquid crystal while keeping the polymerizable liquid crystal in the coating film homeotropically oriented;
The manufacturing method of the optical element characterized by the above-mentioned. A liquid crystal alignment substrate comprising at least a base material having optical transparency and an alignment film for liquid crystal formed on one side of the base material,
Between the liquid crystal alignment film for said base material, or, in the opposite side of the surface is one surface of said substrate, a first birefringent index set forth in any one of claims 1-9 A substrate for aligning liquid crystal, wherein a layer is formed. In the case where the first birefringence layer is formed between the base material and the liquid crystal alignment film, the first birefringence layer is formed on one surface of the base material, and the first birefringence layer is formed. 12. The liquid crystal alignment substrate according to claim 11 , wherein a light absorption color filter is formed on the layer, and the liquid crystal alignment film is formed so as to cover the light absorption color filter. In the case where the first birefringence layer is formed between the substrate and the liquid crystal alignment film, a light absorption color filter is formed on one side of the substrate, and the light absorption color filter is formed on the light absorption color filter. the first birefringence layer is formed through the silicon oxide film, according to claim 11, wherein the liquid crystal alignment layer for so as to cover the first birefringence layer is formed Liquid crystal alignment substrate. A liquid crystal display device comprising a display liquid crystal panel having a first liquid crystal alignment substrate located on the display surface side and a second liquid crystal alignment substrate located on the back side,
The liquid crystal display of at least one of said first substrate for liquid crystal alignment of and the second substrate for liquid crystal alignment, characterized in that a substrate for liquid crystal alignment according to any one of claims 11 to 13 apparatus. It consists of a cross-linked polymer containing a coupling agent and a surfactant that can make homeotropic alignment of a rod-shaped polymerizable liquid crystal, and the cross-linked polymer is a rod-shaped polymerizable liquid crystal homeotropic. A birefringent material characterized in that it has a three-dimensionally cross-linked structure with its orientation maintained.

Images