JP2005115281A - Method for manufacturing retardation plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a highly functional retardation plate which is thin in thickness and has no defect in appearance. <P>SOLUTION: At first, as shown in Figure A, a liquid crystalline compound containing layer 2a is formed on a transparent base material 1 by applying a liquid crystalline compound solution thereon and drying or by applying a molten liquid crystalline compound thereon. Next, as shown in Figure B, the layer 2 is made to turn into a liquid crystal state or is liquified so as to form a molten layer 2b, and an oriented board 3 is brought into contact with the molten layer from above so as to orient the liquid crystalline compound in a specified direction. Then, after the liquid crystalline compound is oriented in the specified direction, as shown in Figure C, the molten liquid crystalline compound containing layer 2b is solidified, the board 3 is removed and the retardation plate 4 composed of the transparent base material 1 and an optically anisotropic layer 2c is manufactured. The retardation plate having a tilt angle is important in terms of optical compensation, and is manufactured by using the oriented board having liquid crystal tilt orientation ability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a retardation plate that is preferably used in an image display device such as a liquid crystal display device (LCD).

  The retardation plate is an important member that realizes an improvement in contrast and an expansion of the viewing angle range in an image display device such as a liquid crystal display device by optical compensation. For the retardation plate, a polymer film is stretched to give optical anisotropy, or an optically anisotropic layer containing a liquid crystalline compound is coated on a substrate such as glass or a polymer film. There is something. In particular, the latter has attracted attention with the recent thinning of liquid crystal display devices.

  In the production of a phase difference plate, in order to form an optically anisotropic layer containing a liquid crystalline compound, the alignment direction of the whole molecule of the liquid crystalline compound or the mesogen portion exhibiting liquid crystallinity is a certain direction or continuous. It is necessary to orient regularly to change. As a method therefor, for example, a method of forming an alignment film on a substrate and further applying a liquid crystalline compound thereon (hereinafter referred to as “alignment film formation method”, see, for example, Patent Documents 1 to 3) ) Further, a method in which a liquid crystalline compound is applied on a separately prepared alignment substrate to form an optically anisotropic layer, and then the optically anisotropic layer is transferred onto a substrate (hereinafter referred to as “transfer method”). For example, see Patent Document 4).

  The outline of the alignment film forming method is as follows, for example. That is, first, a transparent substrate is prepared, and then a liquid for forming an alignment film is applied thereon to form a smooth film. Further, the film is subjected to a rubbing treatment or the like to impart liquid crystal alignment ability to obtain an alignment film. Next, a liquid crystal compound solution is applied on the alignment film and dried, or a liquid crystal compound melt is applied to align the liquid crystal compound. Then, if necessary, the liquid crystalline compound is polymerized, further cooled and solidified, and an optically anisotropic layer is formed to produce a retardation plate. In addition, there is a method in which another alignment layer is formed on a transparent substrate, and the liquid crystalline compound is aligned between two alignment layer formation surfaces of the substrate (for example, Patent Document 5). reference). Furthermore, there is a method in which a rubbing process is directly performed instead of forming an alignment film on a transparent substrate (see, for example, Patent Document 6).

  The outline of the transfer method is as follows, for example. That is, first, an alignment substrate having optical anisotropy, such as a uniaxially stretched polymer film, is prepared. Next, a liquid crystal compound solution is applied and dried thereon, or a liquid crystal compound melt is applied to align the liquid crystal compound. Then, if necessary, the liquid crystalline compound is polymerized, and further cooled and solidified to fix the alignment state, thereby forming an optically anisotropic layer. On the other hand, a base material is prepared and an adhesive or a pressure-sensitive adhesive is applied thereon. As the substrate, for example, an optically isotropic transparent film, an optically anisotropic film having an optical axis different from the alignment direction of the liquid crystalline compound, or the like is used. Then, after the optically anisotropic layer and the adhesive or the like are bonded together, the alignment substrate is removed to complete the transfer, thereby producing a retardation plate.

  However, the alignment film remains in the retardation plate as it is in the alignment film formation method, and the adhesive or the like remains in the retardation plate in the transfer method. These are unnecessary from the viewpoint of the optical function of the retardation plate, and are preferably omitted as much as possible to reduce the thickness. In the alignment film forming method, the adhesion between the alignment film and the optically anisotropic layer may be weak. Patent Document 7 discloses that when a modified PVA alignment film is formed after undercoating (gelatin or the like) on a transparent substrate, adhesion with the liquid crystal layer is improved. The thickness of the retardation plate is further increased by the amount of application, and the manufacturing process becomes complicated.

  Furthermore, the alignment film forming method may leave scratches on the alignment film surface when the rubbing treatment or the like is performed. Since the alignment film remains in the retardation plate as it is, if there is a scratch on the surface of the alignment film, it becomes an appearance defect of the retardation plate as it is. Furthermore, when the rubbing process is performed, foreign matter or the like is fixed on the surface of the alignment film, and it may remain in the retardation plate together with the alignment film. The method of directly rubbing without forming an alignment film on the transparent substrate has the same drawbacks. In the transfer method, when an adhesive or the like is applied, foreign matter or the like is adhered to the surface of the transfer method, which may cause damage to the optically anisotropic layer or partial transfer.

JP 2002-14233 A US Pat. No. 6,215,539 US Pat. No. 6,300,991 Japanese Patent No. 2631015 Japanese Patent Laid-Open No. 9-281480 JP-A-9-281814 JP 9-152509 A

  Therefore, an object of the present invention is to provide a manufacturing method capable of manufacturing a high-performance retardation plate that is thin and has no appearance defect.

In order to solve the above-mentioned problems, the production method of the present invention is a method of producing a retardation plate in which an optically anisotropic layer is formed on a transparent substrate, and the following (1) to (4) Including a process.
(1) A step of forming a liquid crystal compound-containing layer on the transparent substrate having no liquid crystal alignment ability.
(2) A step of bringing the liquid crystal compound-containing layer into contact with an alignment substrate having liquid crystal tilt alignment ability to align the liquid crystal compound of the layer.
(3) The process of fixing the said orientation state of the liquid crystalline compound of the said layer, and forming an optically anisotropic layer.
(4) A step of removing the alignment substrate.

  As described above, according to the manufacturing method of the present invention, unlike the prior art, it is not necessary to leave an alignment film, an adhesive, a rubbing scratch, etc. on the transparent substrate, so that it is thin, has no appearance defects, and has high functionality. Can be manufactured. Moreover, when laminating an optically anisotropic layer containing a liquid crystalline compound on the transparent substrate, it can be laminated without an alignment film, so that the alignment film and the optically anisotropic layer There are no problems due to poor adhesion. Further, a retardation plate having a so-called tilt angle is one of the important members in optical compensation, but according to the present invention, it can be manufactured with the above advantages by using an alignment substrate having a liquid crystal tilt alignment capability. .

  Next, an embodiment of the present invention will be described.

  The thickness of the transparent substrate is not particularly limited, but is preferably as thin as possible for reducing the thickness of the retardation plate, for example, 20 to 120 μm, preferably 20 to 80 μm, and more preferably 20 to 40 μm.

  In the transparent substrate, “transparent” means having a light transmittance that can be applied to a retardation plate. The light transmittance is not particularly limited as long as it is in a range suitable for practical use, but the higher the light transmittance, the more advantageous from the viewpoint of the function of the retardation plate, and ideally 100%.

  The transparent substrate may be optically isotropic, but the transparent substrate has optical anisotropy depending on functions required for a liquid crystal display device on which a retardation plate is mounted. It is preferable. The optical anisotropy in this case is not particularly limited. For example, the optical anisotropy showing a positive or negative A-Plate phase difference characteristic, or the optical anisotropy showing a positive or negative C-Plate phase difference characteristic. Anisotropy, optical anisotropy exhibiting positive or negative O-Plate phase difference characteristics, biaxial optical anisotropy having refractive index anisotropy in different directions (ie, having two optical axes) Sex etc. are possible. Note that A-plate, C-plate, and O-plate all refer to layers having so-called uniaxial optical anisotropy. The A-plate is positive (positive) A-plate when the optical axis is in the in-plane direction and the optical characteristic condition satisfies the following formula (I), and negative when the optical formula condition satisfies the following formula (II). It is called (negative) A-plate.

nx> ny = nz (I)
nx <ny = nz (II)

  The C-plate is a positive C-plate when the optical axis is in the Z-axis direction, that is, in the thickness direction, and the optical characteristic condition satisfies the following formula (III), and the following formula (IV): If the condition is satisfied, it is called a negative (negative) C-plate.

nx = ny <nz (III)
nx = ny> nz (IV)

  In the above formulas (I) to (IV), nx, ny, and nz represent refractive indexes in the X-axis, Y-axis, and Z-axis directions in the layer. However, one of the X axis and the Y axis is an axial direction showing the maximum refractive index in the plane of the layer, and the other is an axial direction in the plane perpendicular to the axis. The Z axis indicates a thickness direction perpendicular to the X axis and the Y axis. In the O-plate, the optical axis direction is inclined as viewed from the in-plane direction and the Z-axis direction (thickness direction perpendicular to the in-plane direction). The means for imparting optical anisotropy is not particularly limited, and a known method may be applied as appropriate. For example, an optical anisotropy transparent film is stretched to impart optical anisotropy. The transparent substrate can be used. Further, for example, a commercially available polymer film or the like having optical anisotropy may be purchased and used as it is as the transparent substrate.

  Although the material of the said transparent base material is not specifically limited, For example, glass, a polymer film, etc. can be used. The polymer that can be used for the polymer film is not particularly limited, but examples thereof include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, and acrylic polymers such as polymethyl methacrylate. , Styrene polymers such as polystyrene, acrylonitrile / styrene copolymer (AS resin), polycarbonate polymers such as bisphenol A / carbonic acid copolymer, linear or branched, such as polyethylene, polypropylene, ethylene / propylene copolymer Polyolefins containing cyclostructures such as polyolefin and polynorbornene, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers Polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, and epoxy polymers. These may be used alone or in combination of two or more. Among the above polymers, more preferred are cellulose polymers such as triacetyl cellulose, polycarbonate polymers such as bisphenol A / carbonic acid copolymer, polyolefins having a cyclo structure such as polynorbornene, and amides such as aromatic polyamides. Polymers and imide polymers are preferred, and cellulose polymers are particularly preferred.

  Moreover, as a material of the said transparent base material, the polymer film of Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) is mention | raise | lifted. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and cyano group in the side chain. Examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film may be, for example, an extruded product of the resin composition.

  The transparent substrate may have a surface subjected to corona discharge treatment, ultraviolet ozone treatment, saponification treatment or the like in order to improve adhesion with the liquid crystalline compound. The transparent substrate may be coated with an optically isotropic layer on one side or both sides. In particular, when a polymer film having optical anisotropy is used as the transparent substrate, the polymer film itself may have a liquid crystal alignment ability. For the purpose of eliminating the liquid crystal alignment ability, etc. Further, it may be coated with the optically isotropic layer. Moreover, even if the transparent substrate is optically isotropic, an optically isotropic layer may be coated on one side or both sides thereof. The thickness of the optically isotropic layer is not particularly limited, but is, for example, 0.05 to 10 μm, preferably 0.1 to 5 μm, and more preferably 0.5 to 2 μm. The material of the optically isotropic layer is not particularly limited. For example, a resin layer or the like can be used, and as the resin, for example, the same materials as the polymers listed as the material of the polymer film are appropriately selected. Can be used. In some cases, the adhesion between the optically anisotropic layer containing a liquid crystalline compound and the transparent substrate can be enhanced by coating the resin layer or the like. The method for coating the optically isotropic layer is not particularly limited. For example, spin coating method, roll coating method, flow coating method, printing method, dip coating method, casting film forming method, bar coating method, gravure method Printing methods and the like can be used as appropriate. At this time, for example, the polymer or the like may be used in the form of a solution or a dispersion, and from the viewpoint that it is difficult to erode the polymer film or the like, for example, an aqueous dispersion is preferable, but methyl ethyl ketone, cyclopentanone, cyclohexanone, etc. A solution using a solvent such as a ketone, an ester such as ethyl acetate, or a hydrocarbon such as toluene may be used.

  The thickness of the optically anisotropic layer containing the liquid crystalline compound is not particularly limited, but is preferably as thin as possible for reducing the thickness of the retardation plate, for example, 0.5 to 10 μm, preferably 1 to 10 μm, More preferably, it is 2-8 micrometers.

  The liquid crystal compound is not particularly limited, and may be a liquid crystal monomer or a polymer. For example, a rod-like liquid crystal compound, a plate-like liquid crystal compound and a polymer thereof can be used, or they can be used alone. Two or more types may be used in combination. In the case of a polymer, it may be a liquid crystal polymer or a liquid crystal prepolymer, and may be a homopolymer or a heteropolymer (copolymer). Examples of the liquid crystalline compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, and alkoxy-substituted phenylpyrimidines. , Liquid crystalline compounds such as phenyldioxanes, tolanes, alkenylcyclohexylbenzonitriles, and polymers thereof are preferable. The liquid crystalline compound preferably contains at least one of a liquid crystal prepolymer and a liquid crystal monomer because the alignment temperature is low and the processing is easy. Furthermore, the temperature range (liquid crystal temperature range) in which the liquid crystal compound-containing layer exhibits a liquid crystal state is appropriately determined depending on the type of the liquid crystal compound. Although the temperature range of the liquid crystal is not particularly limited, it is preferable that the temperature range is not too high from the viewpoint of production and use of the retardation plate, especially considering the deformation of the transparent substrate due to heat in the production process. The liquid crystal temperature range is, for example, 20 to 150 ° C, preferably 20 to 120 ° C, and particularly preferably 20 to 80 ° C. Further, the liquid crystal compound-containing layer may appropriately contain a substance other than the liquid crystal compound, for example, a photopolymerization initiator, a leveling agent, a viscosity modifier, and the like, as long as the function of the retardation plate is not impaired.

  Next, the alignment substrate is an alignment substrate having a liquid crystal tilt alignment capability. Thereby, for example, an optically anisotropic layer having a so-called tilt angle having characteristics such as O-plate can be obtained. The alignment substrate having the liquid crystal tilt alignment ability is not particularly limited, and examples thereof include an alignment substrate including an obliquely deposited film, a photo-alignment film, or a rubbing film. These films can be appropriately formed on a substrate such as glass or a polymer film, for example, to form an alignment substrate having the liquid crystal tilt alignment ability. Among the alignment substrates, an alignment substrate including a photo-alignment film or a rubbing film is preferable because it can be manufactured without using a high-temperature process that damages the base material. The material of the alignment substrate having the liquid crystal tilt alignment ability is not particularly limited, but an alignment substrate containing, for example, a long-chain alkyl polyimide or polysiloxane is preferable. These may be, for example, a long-chain alkyl polyimide rubbing film or a polysiloxane rubbing film provided on the base material, or the base material itself is formed of a long-chain alkyl polyimide, which is rubbed and aligned. A substrate may be used. There are no particular limitations on the method of manufacturing the alignment substrate having the liquid crystal tilt alignment ability. For example, conventional methods may be applied as appropriate. For example, the obliquely deposited film is described in JP-A-5-11252 and the polysiloxane rubbing film is described in JP-A-5-53016.

  An example of the manufacturing method of the present invention will be described based on the process diagram of FIG. That is, first, as shown in FIG. 1A, a liquid crystal compound-containing layer 2 a that is a precursor of an optically anisotropic layer is formed on a transparent substrate 1. This forming method is not particularly limited, but, for example, a method of applying the liquid crystal compound solution to the transparent substrate 1 and drying, or a method of applying the liquid crystal compound melt to the transparent substrate 1 is preferable. In the present invention, “melting” of a liquid crystal compound means a liquid crystal state or a liquefied state.

  When one or both surfaces of the transparent substrate 1 are coated with an optically isotropic layer, it is preferable to form the liquid crystalline compound-containing layer 2a on the optically isotropic layer.

  When the liquid crystalline compound contains a liquid crystal prepolymer or a liquid crystal monomer and is later photopolymerized, it is more preferable to add a photopolymerization initiator thereto. The photopolymerization initiator is not particularly limited, and for example, Irgacure907, Irgacure369, Irgacure184 (all are trade names) manufactured by Ciba Specialty Chemicals, or a mixture thereof is preferable. The addition amount of the photopolymerization initiator is not particularly limited, but is, for example, 0.1 to 5% by weight, preferably 0.1 to 1% by weight with respect to the liquid crystal prepolymer and the liquid crystal monomer. In the solution of the liquid crystal compound, the solvent is not particularly limited as long as it can dissolve the liquid crystal compound. However, when the solution is directly applied on the transparent substrate 1, the transparent substrate 1 is eroded. What is difficult to do is preferable. As the solvent, for example, ketones such as methyl ethyl ketone, cyclopentanone, and cyclohexanone, esters such as ethyl acetate, and hydrocarbons such as toluene can be used.

  The method for applying the liquid crystal compound solution or melt is not particularly limited. For example, spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, A gravure printing method or the like is preferable.

  Next, an alignment substrate is brought into contact with the liquid crystal compound-containing layer 2a to align the liquid crystal compound of the layer. In this step, the liquid crystal compound-containing layer 2a is heated to a temperature higher than the liquid crystal temperature, and the alignment substrate is brought into contact with this state, or the liquid crystal compound-containing layer 2a is brought into contact with the alignment substrate in this state. It is preferable to heat to above the liquid crystal temperature. That is, for example, as shown in FIG. 1B, the liquid crystal compound-containing layer 2a is heated to a temperature higher than the liquid crystal temperature to form a liquid crystal or liquefied layer 2b, and in this state, the alignment substrate 3 is brought into contact with the layer. The liquid crystalline compound in the layer is aligned. Alternatively, for example, the liquid crystal compound-containing layer 2a may be brought into contact with the alignment substrate 3 and heated to the liquid crystal temperature or higher in this state to form the layer 2b in a liquid crystal state or a liquefied state. The liquid crystal temperature range is as described above. FIG. 1A shows the case where the liquid crystal compound-containing layer 2a is formed as a solid. However, the present invention is not limited to this. If the layer is formed in a liquid crystal state or a liquefied state from the beginning, a step of heating later is performed. This is preferable because it can be omitted. For example, the alignment substrate is brought into contact immediately after the melt of the liquid crystal compound is applied, or the alignment substrate is applied immediately after the solution of the liquid crystal compound is applied and dried at a temperature equal to or higher than the liquid crystal temperature. Can be contacted.

  The time for which the alignment substrate 3 is brought into contact with the liquid crystal compound-containing layer 2b is not particularly limited, but is, for example, 10 to 120 seconds, preferably 30 to 60 seconds. The contact direction of the alignment substrate 3 is not particularly limited, and may be set as appropriate according to the purpose.

  Then, the alignment state of the liquid crystal compound in the liquid crystal compound-containing layer is fixed to form an optically anisotropic layer. When the liquid crystalline compound contains at least one of a liquid crystal prepolymer and a liquid crystal monomer, the alignment state is preferably fixed by a method of photopolymerizing the liquid crystalline compound. Although the irradiation light in this case is not specifically limited, For example, an ultraviolet-ray is preferable and the wavelength of the said ultraviolet-ray is more preferably 200-400 nm. The light intensity, irradiation time, and integrated light amount of the irradiation light are not particularly limited as long as the alignment state is sufficiently fixed. Further, the irradiation direction of the irradiation light is not particularly limited as long as the irradiation to the liquid crystal compound-containing layer is not hindered, and the irradiation may be performed from either the transparent substrate side or the alignment substrate side.

  When the liquid crystalline compound is a liquid crystal polymer, the alignment state is preferably fixed by a method of cooling the liquid crystalline compound-containing layer below its liquid crystal temperature. The cooling method is not particularly limited, and may be simply left under room temperature conditions, or may be rapidly cooled using an appropriate cooler.

  Then, as shown in FIG. 1C, the alignment substrate 3 is removed, and the retardation film 4 composed of the transparent base material 1 and the optically anisotropic layer 2c is manufactured.

  The production method of the present invention can be carried out as described above, but this is only one embodiment of the present invention, and all modifications can be made without departing from the gist of the present invention. Steps other than (1) to (4) may be included as appropriate.

  In the case of photopolymerizing the liquid crystalline compound, the conventional method is often performed in an environment such as a nitrogen purge atmosphere. This is because most of the photopolymerization is so-called radical polymerization, and polymerization (curing) is inhibited by oxygen in the atmosphere, and the hardness and durability of the optically anisotropic layer may become insufficient. . However, when performing photopolymerization by the production method of the present invention, if the liquid crystalline compound-containing layer is irradiated with light while being sandwiched between the transparent base material and the alignment substrate, the liquid crystalline compound is inevitably in the atmosphere. It will be photopolymerized in a state where it is difficult to touch. In this way, a retardation plate with sufficient hardness, durability, etc. can be easily obtained without performing a nitrogen purge or the like, and there is an advantage that the manufacturing efficiency of the retardation plate is further improved.

  Next, still another embodiment of the production method of the present invention will be described. However, this is also merely an example, and the present invention is not limited to this embodiment.

  In the production method of the present invention, from the viewpoint of further improvement in production efficiency in production on an industrial scale, the transparent base material is a band-like transparent base material, and the process (1) to It is preferable to perform (4) continuously. And it is preferable that the said alignment substrate is a strip | belt-shaped alignment substrate, and said process (2)-(4) is performed continuously, sending this continuously. At this time, it is more preferable to send out at least one of the transparent base material and the alignment substrate using a roller. It is more preferable to further include a step (5) of winding up the retardation plate. The specific implementation method of such a manufacturing method is not specifically limited, It can implement by applying a conventionally well-known roll-to-roll process etc. suitably, For example, there exists a method demonstrated below.

  FIG. 2 shows a schematic view of an example of an apparatus for carrying out the manufacturing method of the present invention. However, this figure is only an example and does not limit the present invention. As shown in the figure, this apparatus includes rollers 5 to 12, a transparent substrate supply roll 13, a liquid crystal compound solution coating apparatus 14, a drying apparatus 15, an alignment substrate supply roll 16, a heating apparatus 17, a liquid crystal alignment fixing apparatus 18, and an alignment. The substrate winding device 19 and the phase difference plate winding device 20 are main components. Among the rollers 5 to 12, 5, 9 and 10 are guide rolls, 6 is an application roll, 7 and 8 are a pair of opposing laminator rolls, and 11 and 12 are a pair of opposing rollers. Although the material of the rollers 5-12 is not specifically limited, For example, metals, such as stainless steel, rubber | gum, silicone, etc. can be used suitably. The surfaces of the rollers 5 to 12 are preferably as smooth as possible, and the rollers 5 to 12 may be connected to a temperature control device to change the temperature as necessary. Although the liquid crystal compound solution coating apparatus 14 is not particularly limited, for example, an apparatus including coating means such as a coater can be used. The coater is not particularly limited. For example, a coater such as a gravure, a wire bar, or a die can be appropriately used in consideration of physical properties of the liquid crystal compound solution to be used. As the liquid crystal alignment fixing device 18, for example, a cooling device or a light irradiation device can be appropriately used depending on the type of liquid crystal compound to be used. The relationship between the type of liquid crystal compound and the alignment state fixing method is as described above. The light source of the said light irradiation apparatus is not specifically limited, For example, a well-known ultraviolet lamp etc. can be used suitably. In the transparent base material supply roll 13 and the alignment substrate supply roll 16, a strip-shaped transparent base material 21 and a strip-shaped alignment substrate 22 are wound in a roll shape, and the transparent base material 21 and the alignment substrate 22 are continuously rolled by rollers 5 to 12. It is arranged so that it can be sent to. Arrows in the figure indicate directions in which the transparent base material 21 and the alignment substrate 22 are delivered.

  The method for producing a retardation plate using the apparatus of FIG. 2 can be implemented as follows, for example. That is, first, the transparent base material 21 is sent from the transparent base material supply roll 13, and the sent transparent base material 21 passes between the coating roll 6 and the liquid crystal compound solution coating device 14 through the guide roll 5. . Then, the liquid crystal compound solution is applied to the upper surface of the transparent substrate 21 by the liquid crystal compound solution application device 14. Further, the applied liquid crystal compound solution is dried by the drying device 15 to form a liquid crystal compound-containing layer on the upper surface of the transparent substrate 21. This and the alignment substrate 22 delivered from the alignment substrate supply roll 16 are sandwiched between laminator rolls 7 and 8, and the upper surface of the transparent base material 21 (the liquid crystal compound-containing layer application surface) and the alignment substrate 22 are brought into close contact with each other. The state of the liquid crystal compound-containing layer at this time is not particularly limited, but a liquefied state (isotropic state) or a liquid crystal state is preferable because it is easily adhered to the alignment substrate 22. After forming the liquid crystal compound-containing layer, the viscosity may be controlled in order to further improve the adhesion to the alignment substrate 22, and this control method is not particularly limited. For example, an infrared heater (not shown) is used. A known method such as a method or a method of applying warm air can be appropriately used. Next, the transparent base material 21 with the alignment substrate 22 in close contact with the liquid crystal compound-containing layer is further sent out and passed through the heating device 17, where it is heated to liquefy the liquid crystal compound-containing layer. Further, the liquid crystal is sent and passed through the liquid crystal alignment fixing device 18. The heating temperature inside the heating device 17 is not particularly limited, and may be appropriately selected according to the type of the liquid crystalline compound. During this time, the liquid crystalline compound is aligned, and the alignment state is fixed in the liquid crystal alignment fixing device 18 to form an optically anisotropic layer. As described above, the alignment state fixing method varies depending on the type of liquid crystal compound. When the liquid crystal polymer (non-photoreactive compound) is used, the alignment state of the liquid crystal compound is kept solid by virtue of cooling. ) Can be used. The cooling method is not particularly limited, and examples thereof include a method of quenching with cold air or the like, and a method of simply exposing to a room temperature environment. In the case of a liquid crystal monomer or a liquid crystal prepolymer (photoreactive compound), the state can be fixed by photopolymerization (photocuring). The amount of light irradiation is not particularly limited as long as the liquid crystalline compound can be sufficiently cured. As described above, this photopolymerization is efficient because it is easy to obtain a retardation plate having sufficient hardness and durability without performing nitrogen purge or the like. And after the transparent base material 21 in which the said optically anisotropic layer was formed passes the liquid crystal orientation fixing device 18, this is further sent out, it passes through the guide roll 9 and then the guide roll 10, and roller 11 And 12 between. At this time, the alignment substrate winding device 19 peels and removes the alignment substrate 22 from the transparent base material 21 to obtain a target retardation plate 23, which is further wound by the retardation plate winding device 20. As described above, the manufacturing method of the retardation plate using the apparatus of FIG. 2 can be carried out.

  According to the above-described embodiment, the production process of the retardation plate is high and mass production is possible by performing continuously and continuously from the step of feeding the transparent substrate to the step of winding the completed retardation plate. . Furthermore, compared with the case where each process is performed separately and non-continuously, there is an advantage that it is easy to prevent the generation of wrinkles and the adhesion of dust accompanying the preservation of articles in the process of manufacture and the increase of work processes.

  The retardation plate manufactured by the manufacturing method of the present invention is thin, has no appearance defect, and has high functionality. The usage method is not particularly limited, and can be widely used for various optical elements, liquid crystal display elements, and the like.

  The optical element of the present invention is an optical element including the retardation plate of the present invention and a polarizer, and further includes a transparent protective film, and the transparent protective film is interposed between the retardation plate and the polarizer. It is preferable that they are arranged. For example, the optical element of the present invention can be obtained by further laminating the retardation plate of the present invention on a polarizing plate in which a transparent protective film is laminated on a polarizer. In addition, the optical element of the present invention may appropriately include arbitrary components other than these polarizers and transparent protective films. Hereinafter, each component of the optical element of the present invention will be described more specifically.

  The polarizer is not particularly limited, but a stretched film is preferable because good optical characteristics can be easily obtained. For example, a film prepared by adsorbing a dichroic substance such as iodine or a dichroic dye on various films by a conventionally known method, dyeing, crosslinking, stretching, and drying can be used. Among these, a film that transmits linearly polarized light when natural light is incident is preferable, and a film that is excellent in light transmittance and degree of polarization is preferable. Examples of the various films that adsorb the dichroic substance include high hydrophilicity such as polyvinyl alcohol (PVA) film, partially formalized PVA film, ethylene / vinyl acetate copolymer partially saponified film, and cellulose film. In addition to these, for example, polyene oriented films such as PVA dehydrated products and polyvinyl chloride dehydrochlorinated products can be used. Among these, a polyvinyl alcohol polarizing film is preferable because good optical characteristics can be easily obtained. Moreover, although the thickness of the said polarizer is the range of 1-80 micrometers, for example, it is not limited to this.

  The transparent protective film is not particularly limited, and a conventionally known transparent film can be used. For example, a film having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. Specific examples of the material for such a transparent protective film include, for example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene, and the like. , Styrene polymers such as acrylonitrile / styrene copolymer (AS resin), polycarbonate polymers such as bisphenol A / carbonic acid copolymer, linear or branched polyolefins such as polyethylene, polypropylene, ethylene / propylene copolymer, Polyolefins containing a cyclo structure such as polynorbornene, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethers Sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, and epoxy polymers, etc. Furthermore, thermosetting resins such as acrylic, urethane, acrylurethane, epoxy, and silicone, or ultraviolet curable resins are also included. These may be used alone or in combination of two or more. Among these, a TAC film whose surface is saponified with alkali or the like is preferable from the viewpoint of polarization characteristics and durability. In addition, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can be preferably used.

Moreover, it is preferable that the said transparent protective film does not have coloring, for example. Specifically, the retardation value (Rth) in the film thickness direction is preferably in the range of −90 nm to +75 nm, more preferably in the range of −80 nm to +60 nm, and particularly preferably in the range of −70 nm to +45 nm. . When the retardation value is in the range of −90 nm to +75 nm, coloring (optical coloring) caused by the protective film can be sufficiently eliminated. However, Rth in this case shall be represented by the following formula (V). In addition, in a following formula, the definition of nx, ny, and nz is the same as said Formula (I)-(IV), and d shows the film thickness of the said transparent protective film.
Rth = [{(nx + ny) / 2} -nz] × d (V)
Although the thickness of the said transparent protective film is not specifically limited, For example, although it can determine suitably according to a phase difference, protective strength, etc., it is 500 micrometers or less normally, Preferably it is 5-300 micrometers, More preferably, it is the range of 5-150 micrometers. It is.

  The said transparent protective film can be suitably formed by conventionally well-known methods, such as the method of apply | coating the said various transparent resin to a polarizer, the method of laminating | stacking the said transparent resin film on the said polarizer, and uses a commercial item, for example. You can also. Moreover, the transparent base material in the phase difference plate of this invention may serve as the said transparent protective film.

  The transparent protective film may be further subjected to, for example, a hard coat treatment, an antireflection treatment, a treatment for preventing sticking or diffusion, antiglare, and the like. The hard coat treatment is for the purpose of preventing scratches on the surface and the like, for example, is a treatment for forming a cured film made of a curable resin and having excellent hardness and slipperiness on the surface of the transparent protective film. . As the curable resin, for example, an ultraviolet curable resin such as silicone, urethane, acryl, and epoxy can be used, and the treatment can be performed by a conventionally known method. The purpose of preventing sticking is to prevent adhesion between adjacent layers. The antireflection treatment is intended to prevent reflection of external light on the surface of the polarizing plate, and can be performed by forming a conventionally known antireflection layer or the like.

  The anti-glare treatment is intended to prevent visual interference of transmitted light due to reflection of external light. For example, a fine uneven structure is formed on the surface of the transparent protective film by a conventionally known method. Can be done. Examples of a method for forming such a concavo-convex structure include a roughening method by sandblasting or embossing, a method of forming the transparent protective film by blending transparent fine particles in the transparent resin as described above, and the like. It is done.

  Examples of the transparent fine particles include silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like. In addition, conductive inorganic fine particles, crosslinked or uncrosslinked Organic fine particles composed of polymer particles and the like can also be used. Although the average particle diameter of the said transparent fine particle is not specifically limited, For example, it is the range of 0.5-20 micrometers. Moreover, the blending ratio of the transparent fine particles is not particularly limited, but in general, the range of 2 to 70 parts by mass, more preferably 5 to 50 parts by mass, per 100 parts by mass of the transparent resin as described above.

  The antiglare layer containing the transparent fine particles can be used as, for example, the transparent protective film itself, or may be formed as a coating layer on the surface of the transparent protective film. Furthermore, the anti-glare layer may also serve as a diffusion layer (visual compensation function or the like) for diffusing transmitted light to expand the viewing angle.

  The antireflection layer, anti-sticking layer, diffusion layer, antiglare layer and the like are laminated on the polarizing plate as an optical layer composed of, for example, a sheet provided with these layers separately from the transparent protective film. May be.

  Further, the polarizing plate may further include other known optical layers used for forming other optical layers, for example, a reflection plate, a transflective plate, a brightness enhancement film, and the like, such as a liquid crystal display device. One kind of these optical layers may be used, two or more kinds may be used in combination, one layer may be used, or two or more layers may be laminated. Hereinafter, such an integrated polarizing plate will be described.

  First, an example of a reflective polarizing plate or a transflective polarizing plate will be described. In the reflective polarizing plate, a reflective plate is further laminated on the polarizer and the transparent protective film, and in the semi-transmissive reflective polarizing plate, a semi-transmissive reflective plate is further laminated on the polarizer and the transparent protective film.

  The reflective polarizing plate can be used, for example, in a liquid crystal display device (reflective liquid crystal display device) that is disposed on the back side of a liquid crystal cell and reflects incident light from the viewing side (display side). Such a reflective polarizing plate, for example, has an advantage that the liquid crystal display device can be thinned because the built-in light source such as a backlight can be omitted.

  The reflective polarizing plate can be produced by a conventionally known method such as a method of forming a reflective plate made of metal or the like on one surface of a polarizing plate exhibiting an elastic modulus. Specifically, for example, one surface (exposed surface) of the transparent protective film in the polarizing plate is mat-treated as necessary, and a metal foil or a vapor deposition film made of a reflective metal such as aluminum is formed on the surface as a reflection plate. The reflective polarizing plate formed as follows.

  In addition, as described above, a reflective polarizing plate, etc., in which a reflecting plate reflecting the fine uneven structure is formed on a transparent protective film containing fine particles in various transparent resins and having a fine uneven structure on the surface. It is done. A reflector having a fine concavo-convex structure on its surface has an advantage that, for example, incident light can be diffused by irregular reflection to prevent directivity and glaring appearance and to suppress uneven brightness. Such a reflector is, for example, directly on the uneven surface of the transparent protective film by means of a conventionally known method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can form as a metal vapor deposition film.

  Moreover, instead of the method of directly forming the reflector on the transparent protective film of the polarizing plate as described above, a reflective sheet having a reflective layer provided on a suitable film such as the transparent protective film is used as the reflector. May be. Since the reflection layer in the reflection plate is usually composed of metal, for example, from the viewpoint of preventing the decrease in reflectivity due to oxidation, and thus the long-term persistence of the initial reflectivity, separately forming a transparent protective film, etc. The usage form is preferably a state in which the reflective surface of the reflective layer is covered with the film, a polarizing plate or the like.

  On the other hand, the transflective polarizing plate has a transflective reflective plate instead of the reflective plate in the reflective polarizing plate. Examples of the transflective reflector include a half mirror that reflects light through a reflective layer and transmits light.

  The transflective polarizing plate is provided, for example, on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device or the like is used in a relatively bright atmosphere. In a relatively dark atmosphere, it can be used for a liquid crystal display device of a type that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate. That is, the transflective polarizing plate can save the energy of using a light source such as a backlight in a bright atmosphere, and can be used with the built-in light source in a relatively dark atmosphere. It is useful for the formation of etc.

  Next, an example of a polarizing plate in which a brightness enhancement film is further laminated on the polarizer and the transparent protective film will be described.

  The brightness enhancement film is not particularly limited, and for example, a linear multi-layer thin film of dielectric material or a multi-layer laminate of thin film films having different refractive index anisotropy transmits linearly polarized light having a predetermined polarization axis, Other light can be used that reflects light. As such a brightness enhancement film, for example, trade name “D-BEF” manufactured by 3M Co., Ltd. may be mentioned. Also, a cholesteric liquid crystal layer, in particular an oriented film of a cholesteric liquid crystal polymer, or a film in which the oriented liquid crystal layer is supported on a film substrate can be used. These reflect the right and left circularly polarized light and transmit the other light. For example, the product name “PCF350” manufactured by Nitto Denko Corporation, the product name “Transmax” manufactured by Merck, etc. can give.

  In the optical element of the present invention, each component (retardation plate, polarizer, transparent protective film, etc.) may be simply laminated. For example, the optical element further includes an adhesive layer, and all or a part of the components are included. It is preferable to laminate via the adhesive layer. The manufacturing method of such an optical element is not particularly limited, and can be manufactured by a conventionally known method. For example, an adhesive layer is formed by applying a pressure-sensitive adhesive or an adhesive to each component, and this is used. It can manufacture by the method of bonding each said component through. For example, first, the retardation plate of the present invention and a polarizer to which a transparent protective film is bonded are prepared, and then an adhesive is applied to one side of the retardation plate or the transparent protective film, Furthermore, the said optical retardation plate can be bonded together on the said transparent protective film, and the target optical element can be manufactured. The type of the pressure-sensitive adhesive or adhesive is not particularly limited, and can be appropriately determined depending on the material of each component, for example, acrylic, vinyl alcohol, silicone, polyester, polyurethane, polyether, etc. Polymer adhesives, rubber adhesives, and the like. In the present invention, there is no clear distinction between “adhesive” and “adhesive”, but among adhesives, adhesives that are relatively easy to peel off and re-adhere to each other are referred to as “adhesives”. Call. The above-mentioned pressure-sensitive adhesives and adhesives are not easily peeled off due to, for example, the influence of humidity and heat, and are excellent in light transmittance and degree of polarization. Specifically, when the polarizer is a PVA-based film, for example, a PVA-based adhesive is preferable from the viewpoint of the stability of the adhesion treatment. These adhesives and pressure-sensitive adhesives may be applied to the surface of a polarizer or a transparent protective film as they are, for example, or a layer such as a tape or sheet composed of the adhesives or pressure-sensitive adhesives is disposed on the surface. May be. For example, when prepared as an aqueous solution, other additives and catalysts such as acids may be blended as necessary. In addition, when apply | coating the said adhesive agent, you may mix | blend another additive and catalysts, such as an acid, with the said adhesive agent aqueous solution, for example. The thickness of such an adhesive layer is not particularly limited, but is, for example, 1 nm to 500 nm, preferably 10 nm to 300 nm, and more preferably 20 nm to 100 nm.

  Each layer such as the polarizer, transparent protective film, optical layer, and pressure-sensitive adhesive layer forming the optical element of the present invention as described above is, for example, a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, or a cyanoacrylate compound. Further, it may be provided with ultraviolet absorbing ability by appropriately treating with an ultraviolet absorber such as a nickel complex compound.

  The optical element of the present invention can also be manufactured by, for example, a method of sequentially laminating each component on the liquid crystal cell surface or the like in the manufacturing process of a liquid crystal display device or the like. However, it is better to manufacture the liquid crystal display device and the like after laminating the above-mentioned constituent elements in advance and making the optical element of the present invention, for example, the quality stability and the assembly workability are excellent. This is preferable because there is an advantage that the efficiency can be improved.

  The optical element of the present invention has a pressure-sensitive adhesive layer or an adhesive layer as described above on one or both sides of the outer side, for example, since it can be easily laminated on other members such as a liquid crystal cell. Preferably it is. For example, the pressure-sensitive adhesive layer may be a single layer or a laminate. As the laminate, for example, a laminate in which different compositions and different types of single layers are combined can be used. Moreover, when arrange | positioning on both surfaces of the said optical element, the same adhesive layer may respectively be sufficient, for example, a different composition and a different kind of adhesive layer may be sufficient. When the surface of the pressure-sensitive adhesive layer or the like provided on the optical element is exposed as described above, it is preferable to cover the surface with a separator for the purpose of preventing contamination until the pressure-sensitive adhesive layer or the like is put to practical use. . This separator can be formed on a suitable film by, for example, a method of providing a release coat with a release agent such as silicone, long chain alkyl, fluorine, or molybdenum sulfide, if necessary. Although the material of the said film is not specifically limited, For example, the thing similar to the said transparent protective film can be used.

  Although the usage method of the optical element of this invention is not specifically limited, For example, it arrange | positions on the surface of a liquid crystal cell, and is suitable for use for various image display apparatuses.

  Next, the image display apparatus of the present invention will be described. The image display device of the present invention is an image display device including the retardation plate of the present invention or the optical element of the present invention. Other than this, the image display device of the present invention is not particularly limited, and its manufacturing method, structure, usage method, and the like are arbitrary, and conventionally known forms can be applied as appropriate.

  Although the kind of image display apparatus of this invention is not specifically limited, For example, a liquid crystal display device is preferable. For example, the phase difference plate or optical element of the present invention is disposed on one or both sides of a liquid crystal cell to form a liquid crystal panel, which can be used in a liquid crystal display device of a reflective type, a transflective type, a transmissive / reflective type, or the like. The type of the liquid crystal cell forming the liquid crystal display device can be arbitrarily selected, for example, an active matrix drive type represented by a thin film transistor type, a simple matrix drive type represented by a twist nematic type or a super twist nematic type Various types of liquid crystal cells can be used.

  The liquid crystal cell generally has a structure in which liquid crystal is injected into the gap between the opposing liquid crystal cell substrates. The liquid crystal cell substrate is not particularly limited, and for example, a glass substrate or a plastic substrate can be used. The material for the plastic substrate is not particularly limited, and conventionally known materials can be used.

  Further, the optical element of the present invention may be provided on one side or both sides of the liquid crystal cell, and when the members such as the optical element are provided on both sides of the liquid crystal cell, they may be of the same type or different. May be. Furthermore, when manufacturing a liquid crystal display device, for example, appropriate components such as a prism array sheet, a lens array sheet, a light diffusion plate, and a backlight can be arranged in one or more layers at appropriate positions.

  The structure of the liquid crystal panel in the liquid crystal display device of the present invention is not particularly limited, and includes, for example, a liquid crystal cell, the retardation plate of the present invention, a polarizer and a transparent protective film, and the retardation plate on one surface of the liquid crystal cell. The polarizer and the transparent protective film are preferably laminated in this order. Further, the arrangement of the retardation plate of the present invention is not particularly limited. For example, the optical anisotropic layer side faces the liquid crystal cell, and the transparent substrate side faces the polarizer. Can be given.

  When the liquid crystal display device of the present invention further includes a light source, the light source is not particularly limited. However, for example, a planar light source that emits polarized light is preferable because the energy of light can be used effectively.

  Further, the image display device of the present invention is not limited to the liquid crystal display device as described above, and for example, an organic electroluminescence (EL) display, a plasma display (PD), an FED (Field Emission Display), etc. The self-luminous display device may be used. When used in a self-luminous flat display, for example, by setting the in-plane retardation value of the optically anisotropic layer of the retardation plate of the present invention to λ / 4, circularly polarized light can be obtained. It can be used as an antireflection filter.

  The electroluminescence (EL) display device of the present invention will be described below. The EL display device of the present invention is a display device having the retardation plate or optical element of the present invention, and this EL display device may be either an organic EL display device or an inorganic EL display device.

  In recent years, it has been proposed to use, for example, an optical film such as a polarizer or a polarizing plate together with a λ / 4 plate in an EL display device as an antireflection from an electrode in a black state. The phase difference plate and optical element of the present invention, in particular, when linearly polarized light, circularly polarized light, or elliptically polarized light is emitted from the EL layer, or in an oblique direction even if natural light is emitted in the front direction. This is very useful when the emitted light is partially polarized.

  First, a general organic EL display device will be described. The organic EL display generally includes a light emitter (organic EL light emitter) in which a transparent electrode (anode), an organic light emitting layer, and a metal electrode (cathode) are laminated in this order on a transparent substrate. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, or the like. Various combinations such as a laminate of a light-emitting layer and an electron injection layer made of a perylene derivative, or a laminate of the hole injection layer, the light-emitting layer, and the electron injection layer can be given.

  The light emission principle of such an organic EL display device is as follows. That is, by applying a voltage to the anode and the cathode, holes and electrons are injected into the organic light emitting layer, and energy is generated by recombination of the holes and electrons. Then, the fluorescent material is excited by the energy, and emits light on the principle that light is emitted when the fluorescent material returns to the ground state. The mechanism of recombination of holes and electrons is the same as that of a general diode, and current and emission intensity show strong nonlinearity with rectification with respect to applied voltage.

  In the organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes needs to be transparent. Therefore, the organic EL display device is usually formed of a transparent conductor such as indium tin oxide (ITO). A transparent electrode is used as the anode. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is preferably formed of an extremely thin film having a thickness of about 10 nm, for example. This is because the organic light-emitting layer transmits light almost completely as in the transparent electrode. As a result, at the time of non-light emission, the light incident from the surface of the transparent substrate, transmitted through the transparent electrode and the organic light emitting layer, and reflected by the metal electrode again returns to the surface side of the transparent substrate. For this reason, when viewed from the outside, the display surface of the organic EL display device looks like a mirror surface.

  In the organic EL display device of the present invention, for example, the retardation plate or optical element of the present invention is preferably disposed on the surface of the transparent electrode. By having this configuration, an organic EL display device that exhibits effects such as suppression of external reflection and improvement in visibility can be obtained. For example, the optical element of the present invention including the retardation plate and the polarizing plate has a function of polarizing light incident from the outside and reflected by the metal electrode, and therefore the mirror surface of the metal electrode is made external by the polarization action. There is an effect of not letting it be visually recognized. In particular, if the retardation plate of the present invention is a quarter-wave plate and the angle formed by the polarization direction of the polarizing plate and the retardation plate is adjusted to π / 4, the mirror surface of the metal electrode is completely Can be shielded. That is, only the linearly polarized component of the external light incident on the organic EL display device is transmitted by the polarizing plate. The linearly polarized light becomes generally elliptically polarized light by the retardation plate, but becomes circularly polarized light particularly when the retardation plate is a quarter wavelength plate and the angle is π / 4.

  For example, this circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, reflected by the metal electrode, again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and again by the retardation plate. Become. And since this linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it cannot pass through the polarizing plate, and as a result, the mirror surface of the metal electrode can be completely shielded as described above. .

  Next, examples of the present invention will be described. However, the present invention is not limited to the following examples.

  A retardation plate having a tilt angle was produced as follows. That is, first, 1 g of an ultraviolet polymerizable nematic liquid crystalline compound represented by the following chemical formula (1) (Paliocolor LC242 (trade name) manufactured by BASF) and a photopolymerization initiator (Irgacure907 (trade name) manufactured by Ciba Specialty Chemicals) 0 Toluene was added to 0.05 g and stirred for 10 minutes to completely dissolve the solid matter, thereby preparing a liquid crystal compound solution (referred to as coating solution A). At this time, the amount of toluene added was adjusted so that the concentration of the solute was 20% by weight.

一方、水分散型ポリエステル樹脂（東洋紡株式会社製、商品名ＭＤ−１２４５）の２重量％水溶液を調製した（塗工液Ｂとする）。さらに、表面がケン化処理されたトリアセチルセルロース（ＴＡＣ）フィルムを準備し、その片面に前記塗工液Ｂをバーコーターにより塗布し、１２０℃で２分間加熱乾燥し、光学的に等方なポリエステル樹脂層を形成して透明基材とした。そして、この透明基材のポリエステル樹脂層上に前記塗工液Ａを塗布し、１２０℃で２分間加熱乾燥して液晶性化合物含有層を形成した。一方、易接着性ポリエチレンテレフタレートフィルムを準備し、その片面にポリシロキサン系化合物の溶液（コルコート社製、商品名コルコートＰ）を塗布した。これを１２０℃で１分間加熱乾燥してポリシロキサン層を形成し、さらにその表面をラビングして配向膜とし、液晶チルト配向能を有する配向基板を得た。そして、前記液晶性化合物含有層と前記配向膜のラビング面とを密着させ、その状態を保ったまま１２０℃で２分間加熱した。その後、室温環境下で放冷し、前記液晶性化合物含有層の温度が約４０℃となるまで冷却し、紫外線を積算光量で２００ｍＪ／ｃｍ²照射して前記液晶性化合物を重合させて光学的異方性層を形成した。そして前記配向基板を剥離して目的の位相差板を得た。

On the other hand, a 2% by weight aqueous solution of a water-dispersed polyester resin (trade name MD-1245, manufactured by Toyobo Co., Ltd.) was prepared (referred to as coating solution B). Furthermore, a saponified triacetyl cellulose (TAC) film was prepared, and the coating liquid B was applied to one side of the film with a bar coater, dried by heating at 120 ° C. for 2 minutes, and optically isotropic. A polyester resin layer was formed to make a transparent substrate. And the said coating liquid A was apply | coated on the polyester resin layer of this transparent base material, and it heat-dried at 120 degreeC for 2 minute (s), and formed the liquid crystalline compound containing layer. On the other hand, an easy-adhesive polyethylene terephthalate film was prepared, and a solution of a polysiloxane compound (trade name Colcoat P, manufactured by Colcoat Co.) was applied to one surface thereof. This was heated and dried at 120 ° C. for 1 minute to form a polysiloxane layer, and the surface thereof was rubbed into an alignment film to obtain an alignment substrate having liquid crystal tilt alignment ability. Then, the liquid crystal compound-containing layer and the rubbing surface of the alignment film were brought into close contact with each other and heated at 120 ° C. for 2 minutes while maintaining the state. Thereafter, the mixture is allowed to cool in a room temperature environment, cooled until the temperature of the liquid crystal compound-containing layer reaches about 40 ° C., and irradiated with ultraviolet light at an integrated light amount of 200 mJ / cm ² to polymerize the liquid crystal compound. An anisotropic layer was formed. The alignment substrate was peeled off to obtain a target retardation plate.

  The obtained retardation plate was free of white turbidity and was transparent and excellent in light transmittance. This was subjected to phase difference measurement using a spectroscopic ellipsometer (manufactured by JASCO Corporation, M-220 type (trade name)). The result is shown in FIG. As shown in the figure, the retardation plate of this example shows a phase difference characteristic that is asymmetrical to the left and right, and thus was found to be a retardation plate having a tilt angle. The method of measuring the phase difference was based on the normal usage method of the spectroscopic ellipsometer.

A retardation plate having a tilt angle was produced as follows. That is, first, 20 parts by weight of a liquid crystalline copolymer compound represented by the following chemical formula (2) was dissolved in 80 parts by weight of dichloroethane to obtain a liquid crystalline compound solution. However, in chemical formula (2), n and 100-n represent the ratio (mol%) of a monomer unit, respectively, are 0 <= n <= 100, and n is 18 in the present Example. In the chemical formula (2), R ¹ is a hydrogen atom in this example. The liquid crystalline copolymer compound had a weight average molecular weight of 5000.

この溶液を前記塗工液Ａに代えて用いることと、紫外線を照射しないこと以外は実施例１と同様にして位相差板を製造した。得られた位相差板は白濁等がなく透明で光透過性に優れていた。さらに、これを実施例１と同様の方法で位相差測定したところ、左右非対称な位相差特性を示し、チルト角を持つ位相差板であることが分かった。

A phase difference plate was produced in the same manner as in Example 1 except that this solution was used in place of the coating liquid A and ultraviolet rays were not irradiated. The obtained retardation plate was free of white turbidity and was transparent and excellent in light transmittance. Further, when the phase difference was measured in the same manner as in Example 1, it was found that the phase difference plate exhibited a left-right asymmetric phase difference characteristic and had a tilt angle.

A retardation plate was produced as follows. That is, first, an acrylic liquid crystal compound (manufactured by Vantico, CB483 (trade name)) was dissolved in toluene to obtain a liquid crystal compound solution having a concentration of 30% by weight. Next, the transparent base material was produced like Example 1, the said liquid crystalline compound solution was apply | coated on the polyester layer, and it heat-dried at 120 degreeC for 2 minute (s), and formed the liquid crystalline compound containing layer. On the other hand, a liquid for forming a photo-alignment film (manufactured by Vantico, LPPF301 (trade name)) is applied to one side of a glass plate, dried by heating at 150 ° C. for 10 minutes, and further irradiated with polarized ultraviolet rays from an oblique direction to form an alignment film. Thus, an alignment substrate having liquid crystal tilt alignment ability was obtained. And the said transparent base material and the said alignment substrate were bonded together so that the said liquid crystalline compound content layer and the said alignment film might closely_contact | adhere, and it heated at 120 degreeC for 2 minute (s) with the state maintained. Thereafter, the mixture is allowed to cool in a room temperature environment, cooled until the temperature of the liquid crystal compound-containing layer reaches about 40 ° C., and irradiated with ultraviolet light at an integrated light amount of 200 mJ / cm ² to polymerize the liquid crystal compound. An anisotropic layer was formed. The alignment substrate was peeled off to obtain a target retardation plate.

  The obtained retardation plate was free of white turbidity and was transparent and excellent in light transmittance. The phase difference was measured by the same method as in Examples 1 and 2. FIG. 4 shows the result. As shown in the figure, the phase difference plate of the present example shows a phase difference characteristic that is asymmetrical to the left and right, and thus was found to be a phase difference plate having a tilt angle.

(Comparative Example 1)
A retardation plate was produced as follows. That is, first, a liquid for forming a photo-alignment film (manufactured by Vantico, LPPF301 (trade name)) is applied to one side of a glass plate, dried by heating at 150 ° C. for 10 minutes, and further irradiated with polarized ultraviolet rays from an oblique direction. An alignment film having tilt alignment ability was formed to prepare a transparent substrate. Next, a liquid crystal compound solution was prepared in the same manner as in Example 3, which was applied on the alignment film and dried at 120 ° C. for 2 minutes. Then, it stood to cool in room temperature environment, and it cooled until the temperature of the said liquid crystalline compound content layer became about 40 degreeC. Then, the liquid crystalline compound was polymerized by irradiating ultraviolet rays with an integrated light amount of 200 mJ / cm ^{2 in} a nitrogen purge atmosphere, and an optically anisotropic layer was formed to obtain a target retardation plate. This retardation plate was a retardation plate having a tilt angle.

(Comparative Example 2)
A retardation plate was produced in the same manner as in Comparative Example 1 except that ultraviolet irradiation was performed in the air instead of in a nitrogen purge atmosphere. This retardation plate was a retardation plate having a tilt angle.

(Hardness test and cross-cut peel test)
Using the retardation plates of Example 3, Comparative Example 1 and Comparative Example 2, the hardness test and cross-cut peel test of the optically anisotropic layer were performed. The hardness test was performed in accordance with JIS-K5401 using an NEC Corporation MHA-400 (trade name). In the cross-cut peel test, an adhesive tape (manufactured by Nitto Denko Corporation, No. 720 (trade name)) is adhered to and peeled from the optically anisotropic layer of each retardation plate to peel off the optically anisotropic layer. This was done by looking at the condition.

  As a result of the hardness test, in the retardation plate of Comparative Example 1 in which the liquid crystal compound-containing layer was irradiated with ultraviolet rays in a nitrogen purge atmosphere, the indentation hardness of the optically anisotropic layer was 0.50 GPa. This corresponds to B in pencil hardness. On the other hand, in the retardation plate of Comparative Example 2 irradiated with ultraviolet rays in the atmosphere, the indentation hardness of the optically anisotropic layer was insufficient at 0.20 GPa (corresponding to pencil hardness of 4B). In the retardation plate of Example 3, the liquid crystalline compound-containing layer was irradiated with ultraviolet rays in the atmosphere without being purged with nitrogen. The indentation hardness was 0.50 GPa.

  In the cross-cut peel test, the retardation plate of Example 3 showed good results with almost no peeling of the optically anisotropic layer, whereas Comparative Examples 1 and 2 showed most of the optically anisotropic layer. Peeled off, which was an insufficient result. That is, the retardation plate of Example 3 had better adhesion between the transparent substrate and the optically anisotropic layer than Comparative Examples 1 and 2 in which the optically anisotropic layer was formed on the alignment film. .

  As described above, according to the present invention, it is possible to manufacture a retardation film that is thin, has no appearance defect, and has high functionality. In the production method of the present invention, an optically anisotropic layer containing a liquid crystalline compound can be laminated on a substrate without using an alignment film or an adhesive. Further, since the alignment film or the like subjected to the rubbing treatment does not remain in the retardation plate, there is no appearance defect due to the rubbing treatment. Further, there is no problem due to weak adhesion between the alignment film and the optically anisotropic layer. A retardation plate having a so-called tilt angle is one of important members in optical compensation, but according to the present invention, it can be manufactured with the above-described advantages by using an alignment substrate having a liquid crystal tilt alignment capability. Furthermore, when the liquid crystalline compound is photopolymerized by the production method of the present invention, it is easy to obtain a retardation plate with sufficient hardness, durability, etc. without performing nitrogen purging, etc., further improving the production efficiency of the retardation plate. There is also an advantage of doing. If a so-called roll-to-roll process is applied, the production efficiency is further improved. The retardation plate manufactured by the manufacturing method of the present invention can be widely used for various optical elements, image display devices, and the like, and can greatly contribute particularly to thinning of a liquid crystal display.

It is process drawing which shows an example of the manufacturing method of this invention. It is a schematic diagram which shows an example of the apparatus for enforcing the manufacturing method of this invention. 3 is a graph showing the phase difference characteristics of the phase difference plate of Example 1. 6 is a graph showing the phase difference characteristics of the phase difference plate of Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base material 2a Liquid crystalline compound content layer 2b Molten liquid crystalline compound content layer 2c Optically anisotropic layer 3 Orientation board 4 Phase difference plate 5-12 Roller 13 Transparent base material supply roll 14 Liquid crystalline compound solution coating apparatus 15 Drying device 16 Alignment substrate supply roll 17 Heating device 18 Liquid crystal alignment fixing device 19 Alignment substrate winding device 20 Retardation plate winding device 21 Transparent substrate 22 Alignment substrate 23 Retardation plate

Claims (20)

A method for producing a retardation plate in which an optically anisotropic layer is formed on a transparent substrate, comprising the following steps (1) to (4).
(1) A step of forming a liquid crystal compound-containing layer on the transparent substrate having no liquid crystal alignment ability.
(2) A step of bringing the liquid crystal compound-containing layer into contact with an alignment substrate having liquid crystal tilt alignment ability to align the liquid crystal compound of the layer.
(3) The process of fixing the said orientation state of the liquid crystalline compound of the said layer, and forming an optically anisotropic layer.
(4) A step of removing the alignment substrate. One or both surfaces of the transparent substrate are coated with an optically isotropic layer, and the liquid crystalline compound-containing layer is formed on the optically isotropic layer in the step (1). Item 2. The method according to Item 1. The liquid crystal compound comprises at least one of a liquid crystal prepolymer and a liquid crystal monomer, and in the step (3), the alignment state is fixed by a method of photopolymerizing the liquid crystal compound. 2. The production method according to 2. The liquid crystal compound is a liquid crystal polymer, and in the step (3), the fixing of the alignment state is performed by a method of cooling the liquid crystal compound-containing layer below its liquid crystal temperature. 2. The production method according to 2. In the step (1), the method of forming the liquid crystalline compound-containing layer on the transparent substrate is a method in which a solution of the liquid crystalline compound is applied to the transparent substrate and dried, or the liquid crystalline compound The manufacturing method according to claim 1, wherein the melt is applied to the transparent substrate. In the step (2), the liquid crystalline compound-containing layer is heated to a temperature higher than the liquid crystal temperature, and the alignment substrate is brought into contact in this state, or the liquid crystalline compound-containing layer is brought into contact with the alignment substrate. The manufacturing method according to any one of claims 1 to 5, wherein heating is performed at a temperature equal to or higher than the liquid crystal temperature in this state. The manufacturing method according to claim 1, wherein the transparent substrate has optical anisotropy. The manufacturing method according to claim 1, wherein the alignment substrate is an alignment substrate including an oblique deposition film, a photo alignment film, or a rubbing film. The manufacturing method according to claim 1, wherein the alignment substrate is an alignment substrate containing a long-chain alkyl polyimide or polysiloxane. The manufacturing method according to any one of claims 1 to 9, wherein the transparent substrate is a band-shaped transparent substrate, and the steps (1) to (4) are continuously performed while continuously feeding the substrate. The manufacturing method according to any one of claims 1 to 10, wherein the alignment substrate is a strip-shaped alignment substrate, and the steps (2) to (4) are continuously performed while continuously feeding the alignment substrate. The manufacturing method according to claim 10 or 11, wherein at least one of the transparent substrate and the alignment substrate is delivered using a roller. The manufacturing method according to any one of claims 10 to 12, further comprising a step (5) of winding the retardation plate. A phase difference plate manufactured by the manufacturing method according to claim 1. An optical element comprising the retardation plate according to claim 14 and a polarizer. The optical element according to claim 15, further comprising a transparent protective film, wherein the transparent protective film is disposed between the retardation plate and the polarizer. The optical element according to claim 15 or 16, further comprising an adhesive layer, wherein all or a part of the components constituting the optical element are laminated via the adhesive layer. A liquid crystal panel in which the retardation plate according to claim 14 or the optical element according to any one of claims 15 to 17 is disposed on one side or both sides of a liquid crystal cell. An image display apparatus comprising the retardation plate according to claim 14 or the optical element according to any one of claims 15 to 17. A liquid crystal display device comprising the retardation plate according to claim 14, the optical element according to claim 15, or the liquid crystal panel according to claim 18.

Images