WO2006028217A1 - 位相差フィルムおよびその製造方法、光学機能フィルム、偏光フィルム、並びに、表示装置 - Google Patents
位相差フィルムおよびその製造方法、光学機能フィルム、偏光フィルム、並びに、表示装置 Download PDFInfo
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- WO2006028217A1 WO2006028217A1 PCT/JP2005/016641 JP2005016641W WO2006028217A1 WO 2006028217 A1 WO2006028217 A1 WO 2006028217A1 JP 2005016641 W JP2005016641 W JP 2005016641W WO 2006028217 A1 WO2006028217 A1 WO 2006028217A1
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- retardation
- film
- refractive index
- retardation film
- polymer film
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3083—Birefringent or phase retarding elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/08—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of polarising materials
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3016—Polarising elements involving passive liquid crystal elements
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/13363—Birefringent elements, e.g. for optical compensation
Definitions
- the present invention relates to a retardation film used by being incorporated in a display device such as a liquid crystal display device, a manufacturing method thereof, an optical functional film, a polarizing film, and a display device.
- FIG. 17 As a conventional general liquid crystal display device, as shown in FIG. 17, an apparatus having an incident-side polarizing plate 102 A, an emitting-side polarizing plate 102 B, and a liquid crystal cell 104 can be exemplified.
- the polarizing plates 102A and 102B are configured so as to selectively transmit only linearly polarized light (schematically illustrated by arrows in the figure) having a vibration surface in a predetermined vibration direction. They are placed facing each other in a crossed Nicol state so that the directions are perpendicular to each other.
- the liquid crystal cell 104 includes a large number of cells corresponding to pixels, and is disposed between the polarizing plates 102A and 102B.
- the liquid crystal cell 104 includes a VA (Vertical Alignment) method (in the figure, a liquid crystal director) in which nematic liquid crystal having negative dielectric anisotropy is sealed.
- VA Vertical Alignment
- the linearly polarized light that has been transmitted through the incident-side polarizing plate 102A is transmitted through the non-driven cell portion of the liquid crystal cell 104. The light is transmitted without being phase-shifted, and is blocked by the polarizing plate 102B on the emission side.
- the liquid crystal cell 104 when the liquid crystal cell 104 is transmitted through the portion of the driven cell, the linearly polarized light is phase-shifted, and an amount of light corresponding to the amount of the phase shift is transmitted through the polarizing plate 102B on the emission side. Are emitted.
- the liquid crystal display device 100 is not limited to the light transmission and blocking modes described above, and light emitted from the non-driven cell portion of the liquid crystal cell 104 is emitted from the emission side. Light emitted from the part of the driving cell while being transmitted through the polarizing plate 102B A liquid crystal display device has also been devised that is configured to be blocked by the output-side polarizing plate 102B.
- the liquid crystal cell 104 has birefringence and has a thickness. Since the refractive index in the direction and the refractive index in the plane direction are different, light incident along the normal line of the liquid crystal cell 104 out of the linearly polarized light transmitted through the polarizing plate 102A on the incident side is transmitted without being phase-shifted. Of the linearly polarized light transmitted through the polarizing plate 102A on the incident side, the light incident in the direction inclined from the normal line of the liquid crystal cell 104 has a phase difference when passing through the liquid crystal cell 104 and becomes elliptically polarized light.
- This phenomenon is caused by the fact that the liquid crystal cell 104 functions as a C plate having a liquid crystal molecular force positive alignment in the vertical direction.
- the magnitude of the phase difference generated with respect to the light transmitted through the liquid crystal cell 104 depends on the birefringence value of the liquid crystal molecules sealed in the liquid crystal cell 104, the thickness of the liquid crystal cell 104, and the transmitted light. It is also influenced by the wavelength of.
- the display quality of the image observed from the direction inclined from the normal line of the liquid crystal cell 104 is higher than that of the image observed from the front.
- Patent Document 1 In order to improve the problem of viewing angle dependency in the conventional liquid crystal display device 100 as described above, various techniques have been developed so far, and one of them is, for example, Patent Document 1 or Patent.
- a retardation layer having a cholesteric regular molecular structure (a retardation layer exhibiting birefringence) is used, and such a retardation layer is interposed between a liquid crystal cell and a polarizing plate.
- a liquid crystal display device which is arranged so as to perform optical compensation.
- ⁇ nav P (P: helical pitch in the helical structure of liquid crystal molecules, nav: average refractive index in a plane perpendicular to the helical axis ),
- P helical pitch in the helical structure of liquid crystal molecules
- nav average refractive index in a plane perpendicular to the helical axis
- the wavelength is adjusted to be smaller or larger than the wavelength of transmitted light.
- a liquid crystal display device using a (retardation layer exhibiting birefringence) and arranging such a retardation layer between a liquid crystal cell and a polarizing plate to perform optical compensation is also known.
- phase difference is produced, resulting in elliptically polarized light. This phenomenon is caused by the molecular arrangement of cholesteric regularity and the disk-like compound itself acting as a negative C plate.
- the magnitude of the phase difference generated for the light transmitted through the phase difference layer (transmitted light) depends on the birefringence value of the liquid crystal molecules in the phase difference layer, the thickness of the phase difference layer, the wavelength of the transmitted light, etc. Is also affected.
- Non-Patent Document 1 and Non-Patent Document 2 disclose that the viewing angle dependency of the polarizing plate can be improved with the positive C plate and the A plate.
- the retardation layer as described above has a problem in adhesion between the retardation layer and the base material (for example, TAC (cellulose triacetate film) which is a protective film of the polarizing layer).
- the base material for example, TAC (cellulose triacetate film) which is a protective film of the polarizing layer.
- Patent Document 4 it has been proposed to improve the adhesion by heat-treating the liquid crystal and the alignment film.
- this method is effective when the substrate is not a glass substrate and has low moisture and heat resistance (for example, TAC).
- TAC moisture and heat resistance
- the base material stretches and shrinks, and the liquid crystal layer may be peeled off due to this, and it is easily affected by moisture.
- the retardation increasing agent is usually hydrophobic, by mixing it as a whole, both the front and back surfaces of the cellulose acetate film become hydrophobic, and the retardation layer is a polarizing plate comprising a hydrophilic resin such as polyvinyl alcohol. There was also a problem that the adhesiveness at the time of lamination decreased.
- Patent Document 1 Japanese Patent Laid-Open No. 3-67219
- Patent Document 2 JP-A-4 322223
- Patent Document 3 Japanese Patent Laid-Open No. 10-312166
- Patent Document 4 Japanese Patent Laid-Open No. 2003-207644
- Patent Document 5 Japanese Unexamined Patent Publication No. 2000-111914
- Patent Document 6 Japanese Patent Laid-Open No. 2001-249223
- Non-Patent Document 1 J. Chen et al, SID98 Digest, p315 (1998)
- Non-Patent Document 2 T. Ishinabe et al., SIDOO Digest, pi 094 (2000)
- the present invention has been made in consideration of such problems, and there is no problem such as peeling of the retardation layer of the substrate cover that occurs when the retardation layer is formed as described above.
- the main object of the present invention is to provide a retardation film that is highly reliable, can easily obtain an arbitrary retardation value even with a small quantity, and has good adhesion to a hydrophilic film such as a polarizing layer. It is a life.
- a material having a refractive index anisotropy in a polymer film (hereinafter sometimes referred to as a refractive index anisotropic material).
- a retardation film comprising: a retardation film, characterized in that the refractive index anisotropic material has a concentration gradient in the thickness direction of the polymer film.
- the present invention provides, as a second aspect, a retardation film characterized in that a material having refractive index anisotropy is permeated into a polymer film.
- the present invention provides, as a third aspect, a retardation film comprising a polymer film containing a material having refractive index anisotropy, wherein the anisotropic refractive index is obtained.
- a retardation film comprising a polymer film containing a material having refractive index anisotropy, wherein the anisotropic refractive index is obtained.
- a coating liquid in which a refractive index anisotropic material is dissolved in a solvent is applied to the surface of the polymer film, the polymer film is swollen, and the refractive index anisotropic material is infiltrated. It is possible to fill the surface of the polymer film with a refractive index anisotropic material more easily, thereby obtaining a retardation film having a concentration gradient of the refractive index anisotropic material in the thickness direction of the polymer film. Can do. Further, the retardation value as the retardation film can be easily changed by changing the amount and concentration of the coating solution. Therefore, there is an advantage that a retardation film having an arbitrary retardation value can be easily obtained in a small lot.
- the polymer film preferably has regularity in refractive index.
- the refractive index anisotropy material to be filled can reinforce the regularity of the refractive index of the polymer film, and a retardation film having various characteristics can be obtained. It is also the power that can be.
- the refractive index anisotropic material is a material having liquid crystallinity. If it is a material having liquid crystallinity, it may take a liquid crystal structure when filled in the polymer film, and is a force capable of effectively exerting an effect on the polymer film.
- the molecular structure of the refractive index anisotropic material is rod-shaped. This is because by using a refractive index anisotropic material having a rod-like molecular structure, the regularity of the refractive index of the high molecular film can be enhanced.
- the refractive index anisotropic material preferably has a polymerizable functional group. After the refractive index anisotropic material is filled in the polymer film, the refractive index anisotropic material is polymerized using this polymerizable functional group to polymerize it, and then the refractive index is obtained after forming the retardation film. This is because the anisotropic material can be prevented from oozing out and a stable retardation film can be obtained.
- the material having refractive index anisotropy includes a material having a polymerizable functional group and a material having no polymerizable functional group. In this case, it is possible to further enhance the retardation function by using a material having no polymerizable functional group and to improve the reliability of the film by using a material having a polymerizable functional group.
- the concentration gradient in the thickness direction of the polymer film of the material having refractive index anisotropy is such that one surface side of the polymer film has a high concentration and the other surface side has a high concentration.
- the concentration gradient is preferably such that the concentration is low.
- the low-concentration surface side has little or no influence on the inherent properties of the polymer film due to the inclusion or permeation of materials having refractive index anisotropy. If a polarizing film is applied directly to this retardation film, This is because by attaching a polarizing layer to the surface on the concentration side, specifically, the side not filled with the refractive index anisotropic material, a polarizing film without hindering adhesion can be obtained.
- Contact angle force of the retardation film with respect to pure water is preferably different between one surface and the other surface.
- a polarizing film is formed by directly sticking a hydrophilic resin-based polarizing layer such as PVA as a base material to the retardation film, a surface having a lower contact angle is obtained. This is because, when the polarizing layer is adhered to the substrate, a polarizing film can be obtained in which the adhesiveness is not hindered even when an aqueous adhesive is used.
- the concentration gradient of the refractive index anisotropic material in the thickness direction of the polymer film is such that both surface sides of the polymer film have a high concentration and are present in the central portion.
- the concentration gradient may be a low concentration.
- the material having the refractive index anisotropy includes a region having a gentle concentration gradient, and the material having the refractive index anisotropy has a region having a steep concentration gradient. Is preferred. In such a case, the reliability is improved while having a desired phase difference by enhancing the phase difference and enhancing the peel strength, heat resistance, and water resistance.
- the material having the refractive index anisotropy is contained! In the region where the refractive index anisotropic material is not contained, the property of the polymer film remains as it is, and therefore, for example, it is a force that can use the good adhesiveness of the polymer film itself. Further, although the strength of the retardation enhancement region containing the refractive index anisotropic material may decrease, the region having no refractive index anisotropic material as described above has a potential. There are advantages such as the ability to maintain the strength of the phase difference film.
- the retardation film force has a refractive index in the slow axis direction in the in-plane direction of the film as nx, a refractive index in the fast axis direction in the film in-plane direction as ny, and
- Rth [nm] ⁇ (nx + ny) Z2—nz ⁇ X
- the retardation is preferably from 70 to 300 nm. In the present invention, it is possible to substantially expand the range of the retardation value that can be obtained, and in such a case, the viewing angle improvement effect can be improved.
- the haze value when measured in accordance with the above retardation film force JIS-K7105 is preferably 1% or less. In such a case, it is possible to improve the viewing angle improvement effect without disturbing the polarization state.
- the retardation value in the visible light region of the retardation film is preferably larger on the short wavelength side than on the long wavelength side.
- the retardation value in the visible light region of the liquid crystal material used for the liquid crystal layer of the liquid crystal display device is larger on the short wavelength side than on the long wavelength side. Therefore, when the retardation film of the present invention is used as, for example, an optical compensator, it has the advantage that it can compensate for all wavelengths in the visible light region.
- the retardation value in the visible light region of the retardation film may be larger on the long wavelength side than on the short wavelength side.
- the phase difference film of the present invention when used as a polarizing plate by laminating it with a polarizing film, for example, it has excellent advantages in light leakage compensation.
- variation in thickness direction retardation (Rth) of the retardation film measured at a wavelength of 550 nm in the film surface direction is within ⁇ 5 nm based on the average value of Rth. It is preferable that Due to such a small variation, for example, when this retardation film is applied to a display device as an optical compensation film, the display screen is uniformly optically compensated to obtain a display device excellent in display quality such as a viewing angle. The power that can be.
- the retardation film force can be wound into a roll having a minimum diameter of 6 inches or less.
- the retardation film is in the form of a long strip film (also referred to as a web) to increase mass productivity and production efficiency, and is stored, transported, and waited for processing other than during manufacturing, inspection, and post-processing. In the form of a roll wound on a cylinder It is preferable to keep it.
- the present invention also provides a retardation film comprising two or more single-layer retardation films bonded together. In this way, it is possible to realize a retardation value (optical anisotropy value) that cannot be achieved with only one sheet, or a complex optical anisotropy that cannot be achieved with only one sheet. Because it becomes possible to
- the present invention also provides an optical functional film characterized in that the above-mentioned retardation film is directly bonded to an optical functional layer other than the retardation film. Since the optical functional film of the present invention has both the functions of the retardation film of the present invention such as optical compensation and other functions such as antireflection, for example, a film having each function is used. There is an advantage that it does not need to be provided separately.
- the present invention also provides a polarizing film characterized in that the retardation film described above is directly bonded to a polarizing layer.
- a polarizing film is used with a protective film attached to both surfaces of a polarizing layer, but according to the present invention, one of the protective films can be the retardation film described above.
- one of the protective films can be the retardation film described above.
- the present invention provides a display device characterized in that any of the above-described retardation film, optical functional film, or polarizing film according to the present invention is arranged in the optical path.
- the retardation film according to the present invention having an appropriate retardation that eliminates problems such as peeling, a display device with high reliability and high display quality can be obtained.
- the optical functional film according to the present invention it is possible to obtain a display device having excellent display quality without having to provide each of the optical functional layer and the retardation layer.
- the polarizing film according to the present invention it is possible to obtain a display device excellent in display quality without requiring any other optical compensation plate.
- the present invention includes a coating step in which a coating liquid for forming a retardation enhancement region in which a refractive index anisotropic material is dissolved or dispersed in a solvent is applied to at least one surface of a polymer film.
- a coating liquid for forming the retardation enhancement region applied by the application step A permeation step for allowing the refractive index anisotropic material to permeate the polymer film, and a drying step for drying the solvent in the retardation-enhancement region forming coating solution applied by the application step.
- a method for producing a retardation film is provided.
- the present invention it is possible to easily form a retardation film by applying the above-described retardation-enhancing region forming coating solution, and applying the above-described retardation-enhancing region forming coating solution. It is possible to change the retardation value of the obtained retardation film only by changing the amount or the like. Therefore, according to the present invention, there is an advantage that a retardation film having an arbitrary retardation value can be easily obtained even with a small quantity.
- the permeation step may be performed in the drying step. This is because by adjusting the drying temperature or the like, it may be possible to penetrate the refractive index anisotropic material into the polymer film during drying.
- the degree of permeation of the refractive index anisotropic material and further the refractive index anisotropy (retardation value) may be controlled by controlling the drying conditions.
- the present invention it is preferable to have a fixing step of fixing the refractive index anisotropic material that has penetrated into the polymer film after the drying step.
- a fixing step of fixing the refractive index anisotropic material that has penetrated into the polymer film after the drying step For example, in the case where the refractive index anisotropic material has a polymerizable functional group or the like, after the refractive index anisotropic material penetrates into the polymer film, it is polymerized to be polymerized. This is because it is possible to prevent the refractive index anisotropic material from oozing out to the surface force and to improve the stability of the retardation film.
- the retardation film of the present invention is free from problems such as peeling of the retardation layer from the substrate that occurs when the retardation layer is formed, and has reliability such as heat resistance and water resistance, alkali resistance, and reworkability. Even if the lot that is high is small, an arbitrary retardation value can be easily obtained. Furthermore, since the adhesiveness to a hydrophilic film such as a polarizing layer can be improved and the alkali resistance is also excellent, the retardation film is suitable for directly bonding to the polarizing layer.
- the present invention includes a retardation film, a method for producing the same, an optical functional film using the retardation film, a polarizing film, and a display device using these films. Each will be described in detail below.
- the retardation film according to the first aspect of the present invention is a retardation film in which a refractive index anisotropic material is contained in a polymer film, and the refractive index anisotropic material is formed of the polymer film. It has a concentration gradient in the thickness direction and is characterized by
- the retardation film according to the second aspect of the present invention is characterized in that a material having refractive index anisotropy is permeated into a polymer film.
- the retardation film in the third aspect of the present invention is a retardation film in which a material having refractive index anisotropy is contained in a polymer film, wherein the material having refractive index anisotropy is The polymer film has a concentration gradient in the thickness direction, and the concentration gradient changes continuously.
- FIG. 1 is a cross-sectional view showing an example of the retardation film of the present invention.
- a retardation enhancement region 2 containing a refractive index anisotropic material is formed on one surface side of the polymer film 1.
- the concentration gradient of the refractive index anisotropic material in this case is such that the refractive index anisotropic material is contained on the surface 4 side where the concentration on the surface 3 side where the retardation enhancement region 2 is formed is not high. Absent.
- the concentration gradient is any two points in the thickness direction, and if the concentration is different, the refractive index anisotropic material exists in a certain region as described above. In the realm of! There is no material with refractive index anisotropy! ⁇ Includes cases.
- the retardation enhancement region in which the refractive index anisotropic material exists is formed in the retardation film as described above, and the concentration gradient of the refractive index anisotropic material is formed. Since the retardation enhancement region enhances the function as a retardation layer, various optical functions based on birefringence can be achieved. For example, as described later, TAC (cellulose triacetate), which acts as a negative C plate as a high molecular film, When the liquid crystal material having a rod-like molecular structure is used as the refractive index anisotropic material, the retardation film of the present invention is negative because the retardation enhancement region strengthens the function as a negative c plate. The function as a C plate will be strengthened.
- TAC cellulose triacetate
- the retardation film of the present invention is, for example, for forming a retardation enhancement region in which the refractive index anisotropic material is dissolved or dispersed as described in detail in the section "B. Production method of retardation film". Since the coating solution is applied and the surface force of the polymer film is infiltrated with the refractive index anisotropic material and filled in the polymer film, the phase difference enhancement region can be easily formed. Even when compensators with many types of retardation values are required in a lot, a retardation film can be obtained easily and at a low cost.
- the retardation film of the present invention is different from the conventional one in which a retardation layer is formed on a substrate, and the retardation film is filled with a refractive index anisotropic material.
- the phase difference strengthening region and the base material region are formed, there is no problem such as peeling of the retardation layer, which has been a problem in the past, such as heat resistance and water resistance. Reliability increases and it can be used stably.
- the alkali resistance becomes high, for example, it is resistant to acidification treatment when it is bonded to the polarizing layer.
- it since it is excellent in reworkability (usability of repeated use), it is advantageous in terms of process yield.
- the thickness of the polymer film of the material having the above refractive index anisotropy is usually The concentration gradient in the direction will change continuously.
- the stress concentration at a specific interface in the layer is eliminated, so that the peel strength is increased, and the heat resistance and water resistance (repetition of cold heat in the usage environment or contact with water) are increased. (Such as durability against interfacial peeling).
- the polymer film used in the present invention is not particularly limited, but usually a film formed from a resin that transmits light in the visible light region is preferably used.
- transmitting light in the visible light range means that the average light transmittance in the visible light range of 380 to 780 nm is 50% or more.
- the upper case is preferably 70% or more, more preferably 85% or more.
- the light transmittance is measured using a value measured in the atmosphere at room temperature using an ultraviolet-visible spectrophotometer (for example, UV-3100PC manufactured by Shimadzu Corporation).
- the polymer film used in the present invention preferably has a regularity in refractive index. That is, the polymer film used in the present invention preferably has in-plane retardation and Z or thickness direction retardation.
- the retardation film in the present invention obtains a larger retardation value and exhibits the function as an optical functional film such as an optical compensator, but it is not clear, but is assumed to be due to the following reasons. That is, when a polymer film is filled with a refractive index anisotropic material, the filled refractive index anisotropic material further enhances the regularity of refractive index such as birefringence inherent in the polymer film. Thus, it is presumed that retardation films having various characteristics can be obtained. Therefore, the polymer film used in the present invention preferably has a certain degree of refractive index regularity.
- the regularity of the refractive index in the present invention means, for example, (1) that the polymer film acts as a negative C plate, (2) the stretched polymer film is a negative C plate, a positive C plate, It has the characteristic of A plate or biaxial plate.
- the polymer film used in the present invention preferably has a thickness direction retardation (Rth) force in the range of 20 nm to lOO nm, particularly preferably in the range of 25 nm to 80 nm, and more preferably in the range of 30 nm to 60 nm. Preferably within the range of! / ,.
- the in-plane retardation (Re) is preferably in the range of Onm to 300 nm, particularly preferably in the range of Onm to 150 nm, and more preferably in the range of Onm to 125 nm.
- the thickness direction and in-plane direction retardation values are, for example, 23 ° C, 55% RH using an automatic birefringence measuring device (for example, product name: KOBRA-21ADH manufactured by Oji Scientific Instruments).
- a three-dimensional refractive index measurement is performed at a wavelength of 589 nm, and the refractive indexes nx, ny, and nz are obtained.
- the refractive index anisotropic material is dissolved or dispersed in a solvent as described in detail in the section of "B. Method for producing retardation film” described later.
- Phase difference enhancement region Since the coating liquid for forming is applied to the surface of the polymer film and swollen with a solvent, the refractive index anisotropic material penetrates into the polymer film and fills the polymer film. It is preferable that the degree of swelling with respect to a predetermined solvent is high. Specifically, it is preferable that the polymer film swells when the polymer film is immersed in a specific solvent. This phenomenon can be visually discriminated. For example, a polymer film (film thickness; number; zm) is formed, a solvent is dropped on the film, and the swelling of the solvent is observed by observing the penetration of the solvent. Can be confirmed.
- the polymer film used in the present invention may be a flexible material having flexibility or a rigid material having no flexibility, but it is preferable to use a flexible material.
- the production process of the retardation film of the present invention can be a roll-to-roll process, and a retardation film having excellent productivity can be obtained.
- Examples of the material constituting the flexible material include cellulose resin, norbornene polymer, cycloolefin polymer, polymethylol methacrylate, polyvinyl alcohol, polyimide, polyarylate, polyethylene terephthalate, polysulfone, and polyether. Forces that can illustrate sulfone, amorphous polyolefin, modified acrylic polymer, polystyrene, epoxy resin, polycarbonate, polyester, etc. In the present invention, cellulose resin and norbornene polymer can be suitably used.
- Examples of the norbornene-based polymer include a cycloolefin polymer (COP) and a cycloolefin copolymer (COC).
- COP cycloolefin polymer
- COC cycloolefin copolymer
- cycloolefin polymer used in the present invention include, for example, trade name: ARTON manufactured by JSR Corporation.
- cellulose resin it is preferable to use a cellulose ester.
- cellulose esters it is preferable to use a cellulose acylate. SE Since lurosacylates are widely used industrially, they are advantageous in terms of availability.
- lower fatty acid esters having 2 to 4 carbon atoms are preferable.
- the lower fatty acid ester may include only a single lower fatty acid ester, such as cellulose acetate, or may include a plurality of fatty acid esters such as cellulose acetate butyrate or cellulose acetate propionate. It may be.
- cellulose acetate can be particularly preferably used.
- the cellulose acetate it is most preferable to use triacetyl cellulose having an average acetylation degree of 57.5 to 62.5% (substitution degree: 2.6 to 3.0).
- the degree of acetylation means the amount of bound acetic acid per unit mass of cellulose.
- the degree of acetylation can be determined by measuring and calculating the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like).
- the polymer film used in the present invention may be subjected to a stretching treatment. This is because the refractive index anisotropic material may easily penetrate into the polymer film due to the stretching treatment.
- Such stretching treatment is not particularly limited, and may be arbitrarily determined according to the material constituting the polymer film. Examples of the stretching process include a uniaxial stretching process and a biaxial stretching process.
- the configuration of the polymer film used in the present invention is not limited to a configuration composed of a single layer, and may have a configuration in which a plurality of layers are laminated. In the case of a configuration in which a plurality of layers are stacked, layers having the same composition may be stacked, or a plurality of layers having different compositions may be stacked.
- the film thickness of the polymer film used in the present invention is not particularly limited, and may be appropriately selected. Accordingly, the film referred to in the present invention is not limited to a so-called narrow film, but includes a film having a film thickness in a so-called sheet or plate region. However, in general, a relatively thin film is often used.
- the film thickness is preferably in the range of 10 111 to 200 111, particularly in the range of 20 ⁇ m to 100 ⁇ m.
- the retardation value may fluctuate with shrinkage.
- the glass transition temperature force of the polymer film is a temperature between the melting temperature (or melting point).
- the thickness direction retardation (Rth) measured at a wavelength of 550 nm of the polymer film used is used.
- the variation in the film surface direction is preferably within a range of ⁇ 5 nm based on the average value of Rth.
- the refractive index anisotropic material used in the present invention is not particularly limited as long as it can be filled in a polymer film and has birefringence.
- a material having a relatively small molecular weight is preferably used because of easy filling into the polymer film.
- a material having a molecular weight in the range of 200 to 1200, particularly in the range of 400 to 800 is preferably used.
- the molecular weight here refers to a refractive index anisotropic material having a polymerizable functional group, which will be described later, and polymerized in a polymer film, and the molecular weight before polymerization.
- the refractive index anisotropic material used in the present invention is preferably a rod-shaped material in the molecular structure. In the case of a rod-shaped material, it is also a force that can easily enter the gap in the polymer film.
- the refractive index anisotropic material used in the present invention is preferably a material having liquid crystallinity (liquid crystalline molecule).
- the refractive index anisotropic material is a liquid crystalline molecule as described above, there is a possibility that when the refractive index anisotropic material is filled in the polymer film, a liquid crystal state is formed in the polymer film. This is because the birefringence of the refractive index anisotropic material can be more effectively reflected in the retardation film.
- refractive index anisotropic material nematic liquid crystalline molecular material, colles Telic liquid crystalline molecular materials, chiral nematic liquid crystalline molecular materials, smectic liquid crystalline molecular materials, and discotic liquid crystalline molecular materials can be used.
- refractive index anisotropic materials must be nematic liquid crystalline molecular materials. Is preferred. If it is a nematic liquid crystalline molecule material, several to several hundreds of nematic liquid crystalline molecules that have entered the gaps in the polymer film are aligned in the polymer film. That's it.
- the nematic liquid crystal molecule cathode is preferably a molecule having spacers at both ends. Since nematic liquid crystal molecules having spacers at both ends of the mesogen are flexible, they can prevent white turbidity when entering a gap in a polymer film.
- the refractive index anisotropic material used in the present invention those having a polymerizable functional group in the molecule are preferably used, and among them, those having a polymerizable functional group capable of three-dimensional crosslinking are preferable.
- the refractive index anisotropic material after filling in the polymer film, the refractive index anisotropic material can be applied by the action of radicals generated by photo-initiator force by irradiation of light or electron beam. Since the polymer film can be polymerized (cross-linked), it is possible to prevent problems such as the leakage of the refractive index anisotropic material after the retardation film is formed. This is because a retardation film can be used.
- three-dimensional crosslinking means that liquid crystalline molecules are polymerized three-dimensionally to form a network structure.
- polymerizable functional groups that are polymerized by the action of ionizing radiation such as ultraviolet rays and electron beams, or heat are not particularly limited.
- Representative examples of these polymerizable functional groups include radical polymerizable functional groups or cationic polymerizable functional groups.
- radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, and specific examples include a bull group having or not having a substituent.
- an allylate group (generic name including an allyloyl group, a methacryloyl group, an attaryloxy group, and a methacryloyloxy group).
- cationic polymerizable functional group examples include an epoxy group.
- Other polymerizable functional groups include, for example, isocyanate groups, unsaturated triple bonds And the like. Among these, from the viewpoint of the process, a functional group having an ethylenically unsaturated double bond is preferably used.
- a liquid crystal molecule having a rod-like molecular structure and having the above-mentioned polymerizable functional group at the terminal is particularly preferably used.
- nematic liquid crystalline molecules having a polymerizable functional group at both ends are used, they can be polymerized three-dimensionally to form a network structure, resulting in a stronger polymer film. They can do it.
- liquid crystalline molecules having an acrylate group at the terminal are preferably used.
- Specific examples of nematic liquid crystalline molecules having an acrylate group at the end are shown in the following chemical formulas (1) to (6).
- H 2 C CHC0 2 (CH 2 ) 6 0.-CN (2)
- H 2 C CHC 0 2 (CH 2 ) 50- -CH ⁇ H (CH 3 ) C ⁇ 5
- H 2 C C HC0 2 (CH 2 ) s Oi -CH 2 CH (CH 3 ) C 2 H 5
- liquid crystalline molecules represented by the chemical formulas (1), (2), (5) and (6) are DJ Broer et al., Makromol Chem. 190, 3201-3215 (1989) or DJ Broer et al. Makromol Chem. 190 It can be prepared according to or similar to the method disclosed in 2250 (1989).
- the preparation of liquid crystalline molecules represented by the chemical formulas (3) and (4) is disclosed in DE195, 04, 224.
- nematic liquid crystalline molecule having an acrylate group at the terminal include those represented by the following chemical formulas (7) to (17).
- H 2 C CHC0 2 (CH 2 ) 5 CH -COO ⁇ ⁇ CH 2 CH (CH 2 ) C 2 H 5 (12)
- x is an integer of 2 to 5
- two or more refractive index anisotropic materials may be used.
- the refractive index anisotropic material is a liquid crystalline molecule having a rod-like molecular structure, Adjust the blending ratio of the liquid crystal molecules that have one or more polymerizable functional groups at the ends and liquid crystal molecules that have a rod-like molecular structure and one or more polymerizable functional groups at one end. Is preferable because the polymerization density (crosslinking density) and retardation function can be suitably adjusted.
- a rod-like liquid crystalline molecule having one or more polymerizable functional groups at one end is more likely to penetrate into a polymer film and to be easily oriented in Z or the polymer film, so that the retardation function tends to be enhanced more easily. There is also power that there is.
- rod-like liquid crystalline molecules having one or more polymerizable functional groups at both ends can increase the polymerization density, so that the prevention of molecular seepage can be prevented, such as solvent resistance and heat resistance. This is because the durability can be imparted.
- the refractive index anisotropic material used in the present invention is a liquid crystalline molecule having a rod-like molecular structure from the viewpoint of further enhancing the retardation function and improving the reliability of the film. It is preferable to use those having the above-described polymerizable functional group and those having a rod-like molecular structure and having no polymerizable functional group.
- a liquid crystal molecule having a rod-like molecular structure having the above-mentioned polymerizable functional group at both ends and a liquid crystal molecule having a rod-like molecular structure having the above-mentioned polymerizable functional group at one end
- a liquid crystal molecule having a rod-like molecular structure and having no polymerizable functional group at both ends It is preferable to use a liquid crystal molecule having a rod-like molecular structure and having no polymerizable functional group at both ends. This is because rod-like liquid crystalline molecules having no polymerizable functional group are easier to penetrate into the polymer film and are more easily oriented in Z or the polymer film, so that the retardation function is more easily enhanced.
- durability such as solvent resistance and heat resistance can be imparted. Because.
- the present invention is characterized in that the refractive index anisotropic material has a concentration gradient in the thickness direction of the polymer film.
- having a concentration gradient is not particularly limited as long as the concentration is different at any two points in the thickness direction.
- the concentration gradient of the refractive index anisotropic material is such that the concentration gradient is such that one surface side of the polymer film has a high concentration and decreases toward the other surface side (first embodiment). ), And refractive index anisotropy
- Two modes of the mode (second mode) in which the concentration gradient of the material is a concentration gradient in which the both surface sides of the polymer film have a high concentration and become lower toward the center are preferred and can be said to be the modes.
- a mode in which the surface side has a low concentration and has a high concentration region inside the polymer film may be used.
- the concentration gradient in the thickness direction of the polymer film of the refractive index anisotropic material is such that one surface side of the polymer film has a high concentration and the other surface side has a low concentration.
- the concentration gradient is as follows.
- This first embodiment is schematically shown in FIG.
- a phase difference enhancement region 2 containing a refractive index anisotropic material is formed on one surface side 3 of the polymer film 1, and the opposite surface side 4 mm. This is where the substrate region 5 is formed.
- the strong retardation difference region is formed by containing or penetrating a refractive index anisotropic material in the polymer film.
- the state of the polymer film molecules and the refractive index anisotropic material molecules in the retardation enhancement region has not been fully elucidated, but in particular, from the surface of the polymer film composed of linear polymers, the major axis direction. It is presumed that the following state is obtained when the material is manufactured by infiltrating a refractive index anisotropic material composed of rod-like molecules having an electric dipole moment.
- the linear polymers in the polymer film are generally arranged in a plane parallel to the front and back surfaces of the polymer film (however, in the parallel plane, it has a messy directional distribution. )
- the molecules of the rod-like refractive index anisotropic material that have penetrated the surface force of the polymer film are forcibly aligned in direction by the arrangement of the polymer film, and on average, the front and back surfaces of the polymer film. Are arranged in a plane parallel to the plane (however, in the parallel plane, the direction distribution is messy).
- the electric dipole moment vectors of the refractive index anisotropic material are averaged and aligned in a plane parallel to the front and back surfaces of the polymer film.
- the refractive index in the normal direction orthogonal to is relatively lower than the refractive index in the in-plane direction.
- the molecules of the polymer film The chain is encapsulated by a three-dimensional crosslinked body of molecules of refractive index anisotropic material, and the molecular chain of the polymer film is inserted into the network of the three-dimensional crosslinked body of molecules of refractive index anisotropic material.
- the polymer film molecule and the refractive index anisotropic material molecule can be chemically bonded to each other, the polymer film molecule and the refractive index anisotropic material molecule are three-dimensionally cross-linked. It becomes a polymer state.
- the first aspect is characterized in that the retardation enhancement region containing the refractive index anisotropic material is formed on one surface side of the polymer film as described above. Is.
- the concentration gradient of the refractive index anisotropic material in the retardation enhancement region is usually high on the surface side of the polymer film and low on the center side in the thickness direction of the polymer film. Then, the other surface side of the polymer film contains a refractive index anisotropic material, and a base material region which is a region is formed.
- the retardation enhancement region is formed on one surface side of the polymer film as described above, it has the following advantages.
- the refractive index anisotropic material since the refractive index anisotropic material is not contained on the substrate region side, the property of the polymer film remains as it is. Since the refractive index anisotropic material is contained and the substrate region is a region, for example, when the adhesive property of the polymer film itself is good, for example, the polarizing layer is formed on the substrate region side. By adhering, etc., there is an advantage that a polarizing film can be easily formed. In addition, although the strength of the retardation enhancement region containing the refractive index anisotropic material may decrease, the strength as the retardation film can be maintained by having the base material region as described above. And the like.
- the thickness of the retardation enhancement region in the present invention is usually preferably in the range of 0.5 ⁇ m to 8 ⁇ m, particularly preferably in the range of 1 ⁇ to 4 / ⁇ m. If it is smaller than the above range, a sufficient retardation value cannot be obtained, and it is difficult to increase the thickness beyond the above range. Power.
- the determination of whether or not the concentration gradient of the refractive index anisotropic material is as in this embodiment can be made by composition analysis of the phase difference strengthening region and the base material region.
- the retardation film is cut by GSP (precision oblique cutting method) so that a cross section in the thickness direction appears, and time-of-flight secondary ion mass spectrometry (T OF— SIMS) of the cross section is obtained. ) Can be used to measure the concentration distribution of the material in the thickness direction.
- GSP precision oblique cutting method
- time-of-flight secondary ion mass spectrometry for example, TFS-2000 manufactured by Physical Electronics is used as the time-of-flight secondary ion mass spectrometer.
- the primary ion species is Ga +, 1
- the measurement can be performed by measuring positive and Z or negative secondary ions in the cross section in the thickness direction of the retardation film at a secondary ion energy of 25 kV and a subsequent acceleration of 5 kV.
- the concentration distribution in the thickness direction of the refractive index anisotropic material can be obtained by plotting the secondary ion intensity derived from the refractive index anisotropic material with respect to the thickness direction.
- Secondary ions derived from refractive index anisotropy material are filled with refractive index anisotropy material by another analysis method such as cross-sectional TEM observation! The sum of secondary ions observed relatively strongly can be used. Secondary ions derived from the base film are secondary ions that are observed relatively strongly at the surface and at locations where it can be assumed that the refractive index anisotropic material is not filled by another analytical method such as cross-sectional TEM observation. Can be used.
- the contact angle of the retardation film with respect to pure water is different between one surface and the other surface.
- a hydrophilic resin-based polarizing layer such as PVA as a base material
- PVA polarizing layer
- the polarizing layer is adhered to the surface, it is possible to obtain a polarizing film without hindering adhesiveness even when an aqueous adhesive is used.
- one surface of the contact angle of the retardation film to pure water and the other table is preferably 2 degrees or more, more preferably 4 degrees or more, and particularly preferably 5 degrees or more.
- the retardation enhancement region 2 is formed on one surface side 3 of the polymer film 1, and the base material region 5 is formed on the opposite surface side 4.
- the refractive index anisotropic material is contained at a high concentration on one surface side of the polymer film, and the refractive index anisotropic material is at a low concentration on the other surface side.
- the contained form is also included. Even in this case, the low-concentration side has the advantage of being closer to the properties of the polymer film itself than the high-concentration side in terms of surface adhesion and strength.
- the concentration of the refractive index anisotropic material is a low concentration within a range that does not hinder the adhesive property of the polymer film itself, for example,
- the difference in the contact angle of the retardation film with pure water between the high-concentration side surface and the low-concentration side surface should be 2 degrees or more, more than 4 degrees, especially 5 degrees or more. preferable.
- the concentration gradient in the thickness direction of the polymer film of the refractive index anisotropic material is such that the concentration on both surfaces of the polymer film is high and the concentration is reduced toward the center.
- This second embodiment is schematically shown in FIG. As shown in FIG. 2, in this embodiment, a retardation enhancement region 2 containing a refractive index anisotropic material is formed on both surface sides of the polymer film 1, and a base material region is formed in the central portion. 5 is formed.
- the present embodiment is characterized in that the retardation enhancement region containing the refractive index anisotropic material is thus formed on both surface sides of the high molecular film.
- the concentration gradient of the refractive index anisotropic material in this retardation enhancement region is usually high on the surface side of the polymer film and low on the center side in the thickness direction of the polymer film.
- a base material region that is V which does not contain a refractive index anisotropic material, is formed.
- the film thickness of the retardation enhancement region is the same as that in the first aspect, and the description thereof is omitted here.
- the retardation enhancement regions are thus formed on both surface sides of the polymer film. Since it is formed, it has the following advantages.
- the retardation value in the retardation enhancement region is expected to be twice that of the first embodiment.
- the first aspect has an advantage when a larger retardation value is necessary, such as when the retardation value is insufficient.
- the retardation enhancement region containing the refractive index anisotropic material may have a reduced strength as a retardation film, but the central portion does not contain the refractive index anisotropic material. Since it has the base material region, the strength as a retardation film can be maintained.
- the retardation enhancement region 2 containing a refractive index anisotropic material is formed on both surface sides of the polymer film 1, and the substrate region 5 is formed in the central portion.
- the refractive index anisotropic material is contained in a high concentration on both surface sides of the polymer film, and the refractive index anisotropic material is low in the central portion.
- the form contained in concentration is also included. Even in this case, the low-concentration region has an advantage in strength and the like that is closer to the property of the polymer film itself than the high-concentration side.
- the concentration gradient in the thickness direction of the polymer film of the material having the refractive index anisotropy continuously changes.
- the concentration of stress at a specific interface in the layer is eliminated, so the peel strength is increased and the heat resistance and water resistance (use This is because reliability, such as durability against interfacial peeling upon repeated cold heat in the environment or contact with water, alkali resistance, reworkability, and the like are increased.
- the concentration gradient continuously changes when, for example, as shown in FIGS. 3 (a) to (e), the concentration is plotted on the vertical axis and the thickness direction is plotted on the horizontal axis. This is the case where the concentration change in is continuous.
- the concentration gradient of the material having refractive index anisotropy is gentle. It is preferable to have a region and a region where the concentration gradient of the material having the refractive index anisotropy is steep. In such a case, a sufficient amount of a material having a refractive index anisotropy is concentrated in a high concentration and gentle concentration gradient region, and a sufficient retardation value is secured here. In this case, the concentration between the high concentration region and the low concentration region can be continuously connected to prevent stress concentration at the specific interface in the layer, so that the reliability is improved while having a desired phase difference. It is.
- the concentration gradient is gentle, the force and the abrupt are relative relations in the distribution of the concentration gradient in the thickness direction of the material having refractive index anisotropy.
- a region having a gentle concentration gradient and a region having a steep concentration gradient are obtained by macroscopically dividing a region having a relatively small concentration gradient from a region having a relatively small concentration gradient and a region having a large value.
- the region having a gentle concentration gradient includes a region having a constant concentration gradient.
- the region where the concentration gradient is gentle and the force is relatively low in the concentration of refractive index anisotropy material as in the region (A) in FIG. 3 (a) and the region (A) in FIG. 3 (b).
- the region where the concentration gradient is steep is the region where the refractive index anisotropic material is relatively high, as in the region ⁇ ) in FIG. 3 (&) and the region (B) in FIG.
- the region transitioned from the region included in the substrate region to the base material region not including the refractive index anisotropic material is included.
- a concentration gradient as shown in FIGS. 3 (a) and 3 (b) is generally preferable. However, especially when a high retardation value cannot be obtained, as shown in Fig.
- the surface of the high molecular film filled with a high concentration of refractive index anisotropy material is near the center. There is a region where the concentration gradient is steep so that the concentration transitions to a high concentration force and low concentration, and a region where the refractive index anisotropic material is filled at a low concentration at the center side, and the region where the concentration gradient is gentle and forceful. It can be in continuous form!
- the material having the refractive index anisotropy has a region having a gradual concentration gradient and a region having a steep concentration gradient
- a retardation enhancement region 2 containing a refractive index anisotropic material is formed on one surface side 3 of the molecular film 1, and a base material region 5 is formed on the opposite surface side 4.
- Refractive index anisotropy material is contained in the boundary region between the phase difference enhancement region 2 and the base material region 5 from a region having a relatively high concentration gradient and a gradual concentration gradient.
- Base material An example is the case where an intermediate region 9 having a steep concentration gradient is formed.
- the material having the refractive index anisotropy has a region where the concentration gradient is gentle and a region where the concentration gradient is steep, as schematically shown in FIG.
- a retardation enhancement region 2 containing a refractive index anisotropic material is formed on both surface sides of the polymer film 1, and a substrate region 5 is formed in the center portion.
- Refractive index anisotropic material is contained at a relatively high concentration in the boundary region between the reinforced region 2 and the base material region 5 and the refractive index anisotropic material is not included from the region where the concentration gradient is gentle.
- An example is a case where an intermediate region 9 having a steep concentration gradient transitioning to the substrate region is formed.
- the concentration gradient in the thickness direction of the polymer film of the material having refractive index anisotropy changes continuously, or the concentration gradient of the material having refractive index anisotropy is gentle.
- the region and the region having a steep concentration gradient of the refractive index anisotropy indicate that the time-of-flight secondary ion mass analysis (TOF-SIMS) of the cross section in the thickness direction of the retardation film described above It can be judged by concentration distribution analysis.
- TOF-SIMS time-of-flight secondary ion mass analysis
- the retardation film of the present invention preferably has a retardation value in the visible light region of the retardation film that is larger on the short wavelength side than on the long wavelength side.
- the retardation value in the visible light region of the liquid crystal material used for the liquid crystal layer of the liquid crystal display device is larger on the short wavelength side than on the long wavelength side. Therefore, when the retardation film of the present invention is used as an optical compensator, for example, there is an advantage that compensation can be performed at all wavelengths in the visible light source.
- the polymer film and the refractive index anisotropic material have a visible light region. It is preferable to select a retardation value in which the short wavelength side is larger than the long wavelength side.
- the TAC film used for the protective film of the polarizing layer for example, polybulal alcohol (PVA)
- PVA polybulal alcohol
- the retardation film in the visible light region is retarded.
- the long wavelength side may be larger than the short wavelength side.
- the phase difference film of the present invention when used as a polarizing plate by laminating it with a polarizing film, for example, it has excellent advantages in light leakage compensation.
- variation in thickness direction retardation (Rth) in the film surface direction measured at a wavelength of 550 nm of the retardation film is within a range of ⁇ 5 nm on the basis of an average value of Rth. It is preferable. Since the retardation value of the retardation film of the present invention is mainly adjusted by the penetration of the refractive index anisotropic material, for example, compared to a negative C plate retardation film produced by biaxial stretching, It is possible to reduce variations in the in-plane and thickness direction retardation values. When the retardation value is adjusted only by stretching, it is extremely difficult to obtain a uniform phase difference over the entire in-plane region, and the end cannot generally be used.
- the retardation film of the present invention has a small variation in retardation.
- this retardation film when this retardation film is applied as an optical compensation film to a display device, the display screen is uniformly optically compensated for, such as a viewing angle. A display device having excellent display quality can be obtained.
- the thickness direction retardation means the refractive index in the slow axis direction in the in-plane direction of the film (the direction in which the refractive index in the film in-plane direction becomes maximum) is nx, and the progression in the film plane.
- the variation in the thickness direction retardation in the film surface direction can be evaluated, for example, as follows.
- the thickness direction retardation is measured at predetermined intervals over the entire area of the film surface.
- Measurement value force The average value is calculated, and the fluctuation can be calculated by subtracting the average value from each measurement value at predetermined intervals. If the production conditions are not changed over time when the film is a long film, the thickness direction retardation can be assumed to be constant in the longitudinal direction, so the thickness direction retardation is obtained at predetermined intervals in the width direction perpendicular to the longitudinal direction.
- the measured value force average value may be calculated, and the fluctuation may be calculated by subtracting the average value from each measured value at predetermined intervals.
- the retardation film of the present invention preferably has a thickness direction retardation of 70 to 300 nm. In such a case, for example, it is a force that can improve the viewing angle improvement effect.
- the thickness direction and in-plane direction retardation values are measured using an automatic birefringence measurement device (for example, product name: KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.) at 23 ° C and 55% RH.
- an automatic birefringence measurement device for example, product name: KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.
- three-dimensional refractive index measurement is performed at a wavelength of 589 nm, and the refractive indices nx, ny, and nz are obtained.
- the retardation value is adjusted by changing the amount and concentration of the coating liquid and using the means of the retardation enhancement region.
- increasing the stretching ratio causes the retardation film to become cloudy, resulting in a higher haze value and higher depolarization, that is, the polarization state is disturbed and the polarization can be controlled.
- the retardation film of the present invention can achieve a haze value of 1% or less, more preferably 0.8% or less when measured according to JIS-K7105.
- the retardation film of the present invention is one in which at least the refractive index anisotropic material is contained in a polymer film.
- other components are included. May be included.
- a residual solvent, a photopolymerization initiator, a polymerization inhibitor, a leveling agent, a chiral agent, a silane coupling agent and the like may be contained.
- the retardation film of the present invention may be obtained by further laminating other layers.
- another retardation layer may be directly laminated.
- other optical functional layers such as a polarizing layer can be directly laminated.
- a coating liquid for forming a retardation enhancement region in which the refractive index anisotropic material is dissolved or dispersed in a solvent is applied to the surface of the polymer film.
- the refractive index anisotropic material seems to remain in the form of a film on the permeated polymer film surface.
- the retardation film force can be wound into a roll having a minimum diameter of 6 inches or less.
- Retardation films are in the form of long strip films (also called webs) to increase mass productivity and production efficiency during manufacturing, storage, distribution, and post-processing, except during manufacturing, inspection, and post-processing. This is because it is preferable that the rolls are scraped on a cylinder when storing, transporting, and waiting for processing.
- the diameter of the tube that forms the core of this roll is usually 6 inches or less, and in some cases 3 inches. Therefore, it is preferable that the phase difference film can be wound to a minimum diameter of 6 inches or less, more preferably 3 inches or less, in order to be able to cut in a roll shape as advantageous in the process.
- the retardation film obtained in the present invention is one in which the above refractive index anisotropic material is contained in a high molecular film to form a retardation enhancement region.
- a phase difference layer (retardation enhancement region) is included, and the phase difference layer is not included (or the amount is small even if it is included). Therefore, even if a protective layer is not provided, it is possible to obtain a suitable roll shape in which cracks are difficult to occur due to stress concentration when wound in a roll shape.
- the retardation film of the present invention can be used in the form of laminating and laminating two or more if necessary, in addition to the specification of a single layer with only one.
- laminating two sheets the same phase difference film is laminated with two or more layers aligned in the same direction of the main refractive index (direction of optical anisotropy), and the same phase difference film is oriented in the direction of the main refractive index.
- Examples include a configuration in which two or more retardation films having different optical anisotropies are laminated with the main refractive index directions (optical anisotropy directions) different from each other. In these cases, it is possible to realize an optical anisotropy value that cannot be achieved with just one sheet, or to achieve complex optical anisotropy that cannot be achieved with only one sheet. .
- stacking of retardation films are performed by bonding together through a suitable transparent adhesive bond layer, for example.
- the retardation film of the present invention can be used for various applications as an optical functional film.
- Specific examples include an optical compensator (for example, a viewing angle compensator), an elliptically polarizing plate, and a brightness improving plate.
- a TAC film can be used as a polymer film and a liquid crystalline compound having a rod-like molecular structure as a refractive index anisotropic material can be used for a negative C plate.
- the retardation film of the present invention can be used as various optical functional films used in liquid crystal display devices.
- the retardation film of the present invention when used as an optical compensator which is a negative C plate, it is suitably used for a liquid crystal display device having a liquid crystal layer such as a VA mode or an OCB mode.
- the method for producing a retardation film of the present invention is a coating step in which a coating liquid for forming a retardation enhancement region in which a refractive index anisotropic material is dissolved or dispersed in a solvent is applied to at least one surface of a polymer film.
- a drying step of drying the solvent in the phase difference strengthening region forming coating solution is a coating step in which a coating liquid for forming a retardation enhancement region in which a refractive index anisotropic material is dissolved or dispersed in a solvent is applied to at least one surface of a polymer film.
- FIG. 6 is a process diagram showing an example of a method for producing a retardation film of the present invention.
- a coating process for coating the coating film 6 for forming the retardation enhancement region 6 on the polymer film 1 is performed.
- a drying step is performed.
- the refractive index anisotropic material in the retardation-enhancing region forming coating liquid penetrates from the polymer film surface, and the refractive index anisotropic material is contained on the surface side of the polymer film.
- a phase difference strengthening region 2 is formed.
- a retardation enhancement region 2 containing a refractive index anisotropic material and a base material region 5 containing no refractive index anisotropic material are formed in the polymer film.
- Each step may be performed twice or more. For example, first, a coating process for applying the first retardation-enhancing region forming coating solution is performed on the polymer film, and then the first refractive index in the first retardation-enhancing region-forming coating solution. A permeation step for penetrating the anisotropic material into the polymer film and a drying step for drying the solvent in the first retardation-enhancing region forming coating solution are performed. Next, an application step of applying a second phase-enhancement region forming coating solution to the surface coated with the first phase-enhancement region-forming coating solution is performed.
- a permeation step for infiltrating the second refractive index anisotropic material in the phase difference strengthening region forming coating solution and a drying step for drying the solvent in the second phase enhancement region forming coating solution are performed.
- the retardation film may be formed by performing a fixing step from the side where the second phase difference strengthening region forming coating solution is applied.
- the first refractive index anisotropic material does not have a polymerizable functional group that easily penetrates the polymer film! /, And rod-like liquid crystalline molecules are used, and the second refractive index is used.
- Heavy as anisotropic material When a rod-like liquid crystalline molecule having a compatible functional group is used, the polymer film is more easily strengthened in phase difference!
- the surface of the polymer film is formed by coexistence with a region containing rod-like liquid crystalline molecules having a polymerizable functional group on the surface side, and has a more enhanced retardation, while the surface of the polymer film is overlapped by an immobilization process. The effect of being combined and stabilized is obtained.
- the first refractive index anisotropic material a rod-like liquid crystalline molecule having fewer polymerizable functional groups is used
- the second refractive index anisotropic material a rod-like liquid crystalline molecule having more polymerizable functional groups is used.
- the same effect as described above can be obtained.
- the refractive index is not a refractive index anisotropic material.
- the refractive index anisotropic material contained in the retardation-enhancing region forming coating liquid does not have a polymerizable functional group, the polymerizable functional group present on the surface side of the polymer film.
- the coating step in the present invention is a step in which a coating solution for forming a retardation enhancement region in which a refractive index anisotropic material is dissolved or dispersed in a solvent is applied to at least one surface of the polymer film.
- the retardation value of the obtained retardation film can be changed depending on the coating amount of the retardation-enhancing region forming coating solution in the coating step.
- the retardation-enhancing region forming coating solution used in the present invention contains at least a solvent and a refractive index anisotropic material dissolved or dispersed in the solvent, and is indispensable. Other additives are added as needed. Specific examples of such additives include photopolymerization initiators when the refractive index anisotropic material used is a photocurable material. In addition, polymerization inhibitors, leveling agents, chiral agents, silane cutting agents and the like can be mentioned. [0133]
- the refractive index anisotropic material used in the above-mentioned retardation-enhancing region forming coating solution is the same as that described in the column "A. Retardation film" above, The explanation is omitted.
- the refractive index anisotropic material has a polymerizable functional group
- the fixing film process process for polymerizing the refractive index anisotropic material to increase the molecular weight described later.
- the polymer film can be sufficiently swollen and the refractive index anisotropic material can be dissolved or dissolved.
- the solvent is not particularly limited as long as it can be dispersed.
- cyclohexanone is preferably used when the polymer film is TAC and the refractive index anisotropic material is a nematic liquid crystal having an end acrylate.
- the concentration of the refractive index anisotropic material in the solvent in the coating solution for forming a retardation enhancement region of the present invention is not particularly limited, but is usually within the range of 5% by mass to 40% by mass. In particular, the content is preferably in the range of 15% by mass to 30% by mass.
- the coating amount on the polymer film varies depending on the retardation value required for the obtained retardation film.
- the coating amount after drying of the refractive index anisotropic material is 0.8 gZm 2 to in the range of 8gZm 2, it is favorable preferable in particular 1. the range of 6gZm 2 ⁇ 5gZm 2.
- the coating method in this step is not particularly limited as long as it is a method capable of uniformly coating the coating liquid for forming the retardation enhancement region on the surface of the polymer film.
- Bar coating, blade coating, Methods such as spin coating, die coating, slit liner, roll coating, dip coating, ink jet method, and microgravure method can be used.
- the phase applied by the coating step after the coating step, the phase applied by the coating step.
- a drying step for drying the solvent is performed.
- the permeation step is a step of leaving the polymer film after coating so that the refractive index anisotropic material sufficiently permeates and is taken into the polymer film.
- 90% by weight or more, preferably 95% by weight or more, particularly preferably 100% by weight of the refractive index anisotropic material in the retardation-enhancing region forming coating solution is all a polymer. It is preferable that the film penetrates and is taken in. This is because when the refractive index anisotropic material is not penetrated into the polymer film and remains on the surface of the polymer film, the surface becomes cloudy and the light transmittance of the film may be lowered.
- the polymer film after the permeation and drying process preferably has a haze value of 10% or less when the surface on the permeated side is measured in accordance with JIS-K7105. Among them, it is preferably 2% or less, particularly preferably 1% or less.
- the drying step is a step of drying the solvent in the coating solution for forming the retardation enhancement region, and the temperature and time greatly vary depending on the type of solvent used and whether or not it is performed simultaneously with the infiltration step. Different. For example, when cyclohexanone is used as a solvent and is performed simultaneously with the infiltration step, it is usually performed at a temperature in the range of room temperature to 120 ° C, preferably 70 ° C to 100 ° C, for 30 seconds to 10 minutes, preferably A drying process is performed in about 1 minute-5 minutes.
- a fixing step is performed in order to polymerize the refractive index anisotropic material into a polymer.
- a fixing step it becomes possible to prevent the refractive index anisotropic material once taken into the polymer film from leaking out and improve the stability of the obtained retardation film. It is something to be made.
- the refractive index anisotropic material is a crosslinkable compound, if it contains a photopolymerization initiator and is irradiated with ultraviolet rays or an electron beam, it is a thermosetting compound. Heated.
- the optical functional film of the present invention is formed by directly bonding an optical functional layer other than the retardation film to the retardation film described in the section of the above “A. retardation film”.
- the optical functional layer in the present invention comprehensively expresses a desired optical function in cooperation with the retardation film of the present invention in various uses using the retardation film of the present invention. If there is no particular limitation.
- Examples of the optical functional layer in the present invention include an antireflection layer, an ultraviolet absorption layer, and an infrared absorption layer.
- the optical functional film of the present invention is a film having both the functions of the optical functional layers as described above in addition to the functions of the retardation film described in the section “A. Retardation film”. . Since the optical functional film of the present invention has both the functions of the retardation film of the present invention such as optical compensation and other functions such as antireflection, the films having the respective functions are separately provided. It has the advantage that it does not need to be provided.
- the antireflection layer is not particularly limited.
- a high refractive index layer having a higher refractive index than that of the transparent substrate and a low refractive index layer having a lower refractive index than that of the transparent substrate are alternately arranged in this order. Examples of such a layer include those laminated one by one.
- These high-refractive index layers and low-refractive index layers are vacuum-deposited and coated so that the optical thickness represented by the product of the geometric thickness of the layers and the refractive index is 1Z4 of the wavelength of light to be prevented from being reflected. It is formed by construction.
- the constituent material of the high refractive index layer titanium oxide, zinc sulfide and the like are used, and as the constituent material of the low refractive index layer, magnesium fluoride, cryolite and the like are used.
- the ultraviolet absorbing layer is not particularly limited.
- an ultraviolet absorber having a benzotriazole compound, a benzophenone compound, a salicylate compound, etc. in a film such as polyester resin, acryl resin, etc. Can be added to the film.
- the infrared absorbing layer is not particularly limited, and examples thereof include a layer formed by coating an infrared absorbing layer on a film substrate such as polyester resin.
- a film formed by adding an infrared absorbing agent composed of a di-in-molybdenum compound, a phthalocyanine compound or the like into a binder resin having an acrylic resin, a polyester resin or the like is used. It is done.
- the first aspect of the retardation film that is, the concentration gradient of the refractive index anisotropic material is such that one surface side of the polymer film has a high concentration and the other surface A phase difference film having a concentration gradient that tends to be low toward the side and the other surface side being a substrate region is preferably used.
- the surface on which the refractive index anisotropic material does not exist often has better adhesion to the optical functional layer. is there.
- the polarizing film of the present invention is formed by directly laminating a polarizing layer with a polyvinyl alcohol (PVA) adhesive or the like on the retardation film described in the above section “A. Retardation film”. It is what.
- PVA polyvinyl alcohol
- the polarizing film is usually formed by forming a polarizing layer and protective layers on both surfaces thereof.
- the protective layer on one side thereof is the above-described retardation film.
- it can be set as the polarizing film which has an optical compensation function.
- the polarizing layer is not particularly limited, and for example, an iodine-based polarizing layer, a dye-based polarizing layer using a dichroic dye, a polyenic polarizing layer, or the like can be used.
- the iodine-type polarizing layer and the dye-type polarizing layer are generally produced using polyvinyl alcohol.
- the first aspect of the retardation film that is, the concentration gradient of the refractive index anisotropic material is such that one surface side of the polymer film has a high concentration and the other surface side is directed.
- a retardation film having an aspect of a density gradient that is low density by force is preferably used.
- the polarizing layer is usually made of polybulal alcohol (PVA).
- PVA polybulal alcohol
- the force depends on the type of polymer film used for the retardation film. This is because the adhesiveness is better on the surface on the side where no is present.
- Examples of the display device in the present invention include a liquid crystal display device and an organic EL display device.
- a first aspect of the display device of the present invention is characterized in that the above-described retardation film according to the present invention is arranged in an optical path.
- the display device of the present invention is excellent in display quality with high reliability because a retardation film having an appropriate retardation that eliminates problems such as peeling is disposed.
- FIG. 7 is a perspective view showing an example of a liquid crystal display device among the display devices of the present invention.
- the liquid crystal display device 20 of the present invention includes an incident-side polarizing plate 102A, an outgoing-side polarizing plate 102B, and a liquid crystal cell 104.
- the polarizing plates 102A and 102B are configured to selectively transmit only linearly polarized light having a vibration surface in a predetermined vibration direction, and are cross-linked so that the respective vibration directions are perpendicular to each other. They are placed facing each other in the coll state.
- the liquid crystal cell 104 includes a large number of cells corresponding to pixels, and is disposed between the polarizing plates 102A and 102B.
- the liquid crystal cell 104 employs a VA (Vertical Alignment) method in which nematic liquid crystal having negative dielectric anisotropy is sealed.
- VA Vertical Alignment
- the linearly polarized light that has passed through 102A passes through the non-driven cell portion of the liquid crystal cell 104 without being phase-shifted, and is blocked by the output-side polarizing plate 102B.
- the linearly polarized light is phase-shifted, and an amount of light corresponding to the amount of the phase shift is transmitted through the output-side polarizing plate 102B. Emitted.
- VA Vertical Alignment
- the liquid crystal display device 20 having such a constitutional power, the liquid crystal cell 104 and the polarizing plate 102B on the emission side (a polarizing plate that selectively transmits light in a predetermined polarization state emitted from the liquid crystal cell 104).
- the retardation film 10 according to the present invention described above is disposed in the optical path, and the method of the liquid crystal cell 104 out of the light having a predetermined polarization state emitted from the liquid crystal cell 104 by the retardation film 10. Compensates the polarization state of light emitted in the direction inclined from the line You can be!
- the reliability according to the present invention described above is high between the liquid crystal cell 104 of the liquid crystal display device 20 and the polarizing plate 102B on the emission side.
- the phase difference film 10 is arranged to compensate for the polarization state of the light emitted from the liquid crystal cell 104 in the direction in which the normal force of the liquid crystal cell 104 is tilted, so that it depends on the viewing angle in the liquid crystal display device 20. It is possible to effectively improve the problem of display property, excellent display quality, and high reliability.
- the liquid crystal display device 20 shown in FIG. 7 is a transmission type in which light is transmitted from one side in the thickness direction to the other side, but the embodiment of the display device according to the present invention is the same.
- the retardation film 10 according to the present invention described above which is not limited thereto, can be used by being incorporated in a reflective liquid crystal display device in the same manner. Further, it can be used by being incorporated in the optical path of other display devices as described above.
- the retardation film 10 according to the present invention described above is disposed between the liquid crystal cell 104 and the polarizing plate 102B on the emission side.
- the retardation film 10 may be disposed between the liquid crystal cell 104 and the polarizing plate 102A on the incident side.
- the retardation film 10 may be disposed on both sides of the liquid crystal cell 104 (between the liquid crystal cell 104 and the incident-side polarizing plate 102A and between the liquid crystal cell 104 and the outgoing-side polarizing plate 102B).
- the number of retardation films disposed between the liquid crystal cell 104 and the incident-side polarizing plate 102A or between the liquid crystal cell 104 and the output-side polarizing plate 102B is not limited to one, and a plurality of retardation films are disposed. Also good. Furthermore, another optical function film may be disposed in the optical path.
- a second aspect of the display device of the present invention is characterized in that the above-described optical functional film according to the present invention is arranged in an optical path. By doing so, it is not necessary to separately provide an optical functional plate having a function other than the retardation film, and a display device with high display quality and high reliability can be obtained.
- FIG. 8 is a perspective view showing an example of a liquid crystal display device among the display devices of the present invention.
- the liquid crystal display device 30 of the present invention includes an incident-side polarizing plate 102A, an outgoing-side polarizing plate 102B, and a liquid crystal cell 104.
- Polarizers 102A and 102B, and liquid crystal The cell 104 can be the same as that shown in FIG. 7 and is arranged as shown in FIG.
- the above-described optical functional film 40 according to the present invention is arranged in the optical path between the liquid crystal cell 104 and the output-side polarizing plate 102B.
- the function of the optical function film is not particularly limited. However, when the optical compensation function has an ultraviolet absorption function, the optical function film 40 causes the liquid crystal cell 104 to have a predetermined polarization state emitted from the liquid crystal cell 104. Compensate the polarization state of the light emitted in the direction inclined from the normal, and absorb the ultraviolet rays derived from sunlight incident on the liquid crystal display device from the outside to improve the light resistance of the liquid crystal display device It has become possible to do.
- the reliability according to the present invention described above is high between the liquid crystal cell 104 of the liquid crystal display device 30 and the polarizing plate 102B on the emission side.
- the optical functional film 40 is arranged to compensate for the polarization state of the light emitted from the liquid crystal cell 104 in a direction inclined from the normal line of the liquid crystal cell 104, so that the viewing angle dependence of the liquid crystal display device 30 is compensated.
- the problem can be effectively improved, and the light resistance can be improved by, for example, an ultraviolet absorption function, and the display quality is excellent.
- the embodiment of the display device according to the present invention is not limited to this, and the above-described optical functional film 40 according to the present invention may be incorporated and used in a reflective liquid crystal display device as well. it can. Further, it can be used by being incorporated in the optical path of other display devices as described above.
- the optical functional film 40 is disposed between the liquid crystal cell 104 and the polarizing plate 102B on the emission side.
- the optical functional film 40 may be disposed between the liquid crystal cell 104 and the polarizing plate 102A on the incident side.
- the optical functional film 40 may be disposed on both sides of the liquid crystal cell 104 (between the liquid crystal cell 104 and the incident-side polarizing plate 102A and between the liquid crystal cell 104 and the output-side polarizing plate 102B).
- the optical functional film 40 may be disposed on the outer side (surface side) of the polarizing plate 102B on the emission side.
- the liquid crystal cell 104 and the incident side polarizing plate 102A, or the liquid crystal cell 104 and the output side polarizing plate 102B, or the output side polarizing plate 102 The number of films disposed outside B is not limited to one, and a plurality of films may be disposed.
- a third aspect of the display device of the present invention is characterized in that the above-described polarizing film according to the present invention is arranged in an optical path. By doing so, it is possible to obtain a display device that is highly reliable and does not require any other optical compensation plate, and that has high display quality.
- FIG. 9 is a perspective view showing an example of a liquid crystal display device among the display devices of the present invention.
- a liquid crystal display device 50 of the present invention includes a polarizing plate 102A on the incident side, a polarizing film 60 according to the present invention on the output side, and a liquid crystal cell 104.
- the polarizing plate 102A and the polarizing film 60 according to the present invention are configured so as to selectively transmit only linearly polarized light having a vibration surface in a predetermined vibration direction, and the vibration directions thereof are mutually perpendicular. They are placed facing each other in a cross-coll state so as to be in a relationship.
- the liquid crystal cell 104 may be the same as that shown in FIG. 7, and is disposed between the polarizing plate 102A and the polarizing film 60 according to the present invention.
- the above-described highly reliable polarizing film 60 according to the present invention is disposed on the liquid crystal cell 104 and the emission side of the liquid crystal display device 50, so that the liquid crystal cell 104 Since the polarization state of the light emitted from the liquid crystal cell 104 in the direction inclined from the normal line of the liquid crystal cell 104 is compensated, the problem of the viewing angle dependency in the liquid crystal display device 50 can be effectively improved.
- the display quality is excellent and the reliability is high.
- the embodiment of the display device according to the present invention is not limited to this, and the above-described polarizing film 60 according to the present invention may be incorporated in a reflective liquid crystal display device as well. it can. Further, it can be used in the same manner in the optical path of other display devices as described above.
- the polarizing film 60 according to the present invention described above is disposed on the liquid crystal cell 104 and the output side. It may be arranged on the side. Further, the polarizing films 60 and 60 ′ according to the present invention may be disposed on both sides of the liquid crystal cell 104. It should be noted that a separate retardation film or other optical functional film disposed between the liquid crystal cell 104 and the incident-side polarizing plate 102A or between the liquid crystal cell 104 and the output-side polarizing film 60 may be disposed. Good.
- the liquid crystal display device has been described as an example.
- the retardation film and the polarizing film can also be used for other display devices.
- the organic EL display in which the retardation film or polarizing film according to the present invention functioning as a circularly polarizing plate is disposed in the optical path.
- An apparatus etc. are also mentioned.
- the present invention is not limited to the above-described embodiment.
- the above embodiment is an exemplification, and any device that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects can be used. It is included in the technical scope.
- Photopolymerizable liquid crystal compound (compound (1) below) as a refractive index anisotropic material is dissolved in cyclohexanone by 20% by mass, and TAC film (Fuji Photo Film Co., Ltd., trade name: TF8 0UL)
- TAC film Fluji Photo Film Co., Ltd., trade name: TF8 0UL
- the material film surface was coated by bar coating so that the coating amount after drying was 2.5 g Zm 2 . Next, it was heated at 90 ° C. for 4 minutes to remove the solvent by drying, and the photopolymerizable liquid crystal compound was permeated into the TAC film.
- a retardation film was produced by fixing the photopolymerizable liquid crystal compound by irradiating the coated surface with ultraviolet rays. The obtained retardation film was used as a sample and evaluated according to the following items.
- the phase difference of the sample was measured by an automatic birefringence measuring apparatus (manufactured by Oji Scientific Instruments, trade name: KOBRA-21ADH). Anisotropy that increases the phase difference of the substrate film was confirmed from the chart of the optical phase difference and the incident angle of the measurement light when the measurement light was perpendicularly or obliquely incident on the sample surface.
- the alignment direction of the liquid crystal molecules is that the liquid crystal molecules exist in a plane parallel to the surface of the substrate film, and the alignment direction in the plane is Is considered to be a homogenous orientation that is random.
- the embedded resin was applied to the liquid crystal coated surface of the sample, cut in the thickness direction, and the cross section of the sample was observed by SEM. The result is shown in FIG. As is clear from FIG. 10, there was no layer between the film surface and the embedded resin, and it was determined that the liquid crystal compound had penetrated into the polymer film by combining the above phase difference measurement results. .
- the surface of the sample liquid crystal coated surface was protected with a metal oxide, and after embedding the epoxy resin, it was adhered to the cryosupport.
- a trimming Z-surface was created with an ultramicrotome equipped with a diamond knife using a cryosystem, vapor-stained with metal oxide, and TEM observation was performed after ultrathin sections were prepared.
- FIG. 11 the refractive index anisotropic material permeation side of the sample is divided into three layers (a high concentration region in the retardation enhancement region, an intermediate region in the retardation enhancement region, and a substrate region)). It was divided.
- the haze value was measured with a turbidimeter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: ND H2000) according to JIS-K7105. As a result, 0.35% was good.
- Adhesion level (%) (Peeled-off force part Z taped area) X loo
- the sample was immersed in hot water at 90 ° C for 60 minutes, and the optical characteristics and adhesion were measured by the method described above. As a result, there was no change in optical properties and adhesion before and after the test.
- the sample was allowed to stand for 24 hours in an environment of 80 ° C and 95% humidity, and the optical properties and adhesion were measured by the methods described above. As a result, there was no change in optical properties and adhesion before and after the test. In addition, no exudation of the refractive index anisotropic material or white turbidity was observed after the test.
- the sample was immersed in an alkaline aqueous solution (1.5N aqueous sodium hydroxide solution) at 55 ° C for 3 minutes, washed with water and dried, and the optical properties and adhesion were measured by the methods described above. As a result, there was no change in optical properties and adhesion before and after the test. Also, no coloring was seen o
- Measurement conditions are: positive and negative secondary ion polarity, mass range (MZZ) 0 to: L000, raster size 180 m, measurement time 3 minutes, no energy filter, contrast diaphragm 0 #, post acceleration 5 kV, measurement vacuum is 4 X 10 " 7 Pa (3 X 10 _9 Torr, primary ion species is Ga +, primary ion energy is 25 kV, sample potential is +3.2 kV, pulse The frequency was 8.3 kHz, the pulse width was 12 ns, no bunching, charge neutralization was performed, and the time resolution was 1. Ins / ch.
- the concentration of the refractive index anisotropic material is relatively high up to about 1.5 m from the coating surface. This is a region where the concentration gradient is gentle, and there is a region where the concentration of refractive index anisotropic material is attenuated and the concentration gradient is steep around 1.5 ⁇ m to 3 ⁇ m. As a result, it has become clear that there is a substrate region that hardly contains refractive index anisotropic material. This is a cross section by TEM where the refractive index anisotropic material permeation side was observed to be divided into three layers (high concentration region in retardation enhancement region, intermediate region in retardation enhancement region, and substrate region). Consistent with observation results.
- Example 1 a retardation film was prepared in the same manner as in Example 1 except that the solvent was a mixed solvent of cyclohexanone and methylethylketone (MEK) (solvent ratio 7: 1). .
- MEK methylethylketone
- the obtained retardation film was subjected to optical properties, adhesion, wet heat resistance test, and As a result of the water resistance test, the same results as in Example 1 were obtained.
- a retardation film was produced in the same manner as in Example 1 except that the solvent was a mixed solvent of cyclohexanone and MEK (solvent ratio 7: 1) and the coating method was die coating.
- the obtained retardation film was evaluated in the same manner as in Example 1. As a result, the same results as in Example 1 were obtained.
- the contact angles of the retardation enhancement region surface and the substrate region surface of the retardation film obtained in Example 1 were measured. Specifically, the contact angle of pure water on the surface of the retardation enhancement region and the surface of the substrate region (TAC surface) with pure water was measured with a contact angle measuring device (C-Z type manufactured by Kyowa Interface Science Co., Ltd.). The contact angle was measured 30 seconds after dropping 0.1 ml of pure water on the measurement surface. As a result, the surface of the retardation enhancement region is 62.6 ° and the surface of the substrate region is 57.3 °, and the surface of the retardation enhancement region has a higher value, and the surface that is not the retardation enhancement region is more hydrophilic. The result of having was obtained.
- Example 1 samples were prepared by changing the coating amount after drying to 2.0, 2.6, 3.2, and 3.8 gZm 2, and the same evaluation was performed. As a result, similar results were obtained. Furthermore, there is a linear relationship between the coating amount and the phase difference (retardation value measured at an angle of 30 ° with respect to the normal direction: 30 ° Re) as shown in Fig. 14. I found that I could control it o
- Photopolymerizable liquid crystal compound as a refractive index anisotropic material (the following compound (1)), a mixed solvent of hexa non and n- propyl alcohol cyclohexane (solvent ratio 9: 1).
- solvent ratio 9: 1 a mixed solvent of hexa non and n- propyl alcohol cyclohexane
- TAC The substrate (made by Fuji Photo Film Co., Ltd., trade name: TF80UL) was coated on both sides so that the coating amount after drying was lgZm 2 on one side by bar coating on the surface of the base film that also had the strength.
- the solvent was dried and removed by heating at 70 ° C. for 4 minutes, and the photopolymerizable liquid crystal compound was permeated into the TAC film.
- the photopolymerizable liquid crystal compound was immobilized by irradiating the coated surface with ultraviolet rays.
- the phase difference of the sample was measured with an automatic birefringence measurement apparatus (manufactured by Oji Scientific Instruments, trade name: KOBRA-21ADH). Anisotropy that increases the phase difference of the substrate film was confirmed from the chart of the optical phase difference and the incident angle of the measurement light when the measurement light was perpendicularly or obliquely incident on the sample surface. Figure 15 shows the dependence on the phase difference angle. Further, when the haze value was measured in the same manner as in Example 1, it was 0.7%.
- a retardation film was prepared in the same manner as in Example 6 except that coating was performed on one side of the substrate film so that the coating amount after drying was 3 gZm 2 on one side.
- phase difference of the sample was measured by an automatic birefringence measuring apparatus (manufactured by Oji Scientific Instruments, trade name: KOBRA-21ADH).
- Figure 15 also shows the dependence on the phase difference angle. Further, when the haze value was measured in the same manner as in Example 1, it was 0.5%.
- Example 6 and Example 7 are compared, as shown in FIG. 15, in order to obtain the same degree of phase difference, it is better to coat both sides and provide a phase difference enhancement region on both sides. Compared to coating only on one side and providing a phase difference enhancement region only on one side, it was found that there is an advantage that the total coating amount of the refractive index anisotropic material can be reduced.
- the same photopolymerizable liquid crystal compound as in Example 1 as a refractive index anisotropic material (the compound (1)) cyclohexanone in was 20 mass 0/0 dissolved cyclohexane, width 650 mm, elongated TAC fill arm length 30m (Fuji Photo Film Co., Ltd., trade name: TF80UL) Coating was carried out on the surface of the base film having sufficient force so that the coating amount after each drying was 3 gZm 2 . Subsequently, the solvent was dried and removed by heating at 90 ° C. for 4 minutes, and the photopolymerizable liquid crystal compound was permeated into the TAC film.
- the above-mentioned photopolymerizable liquid crystal compound was fixed by irradiating the coated surface with ultraviolet rays to produce a retardation film according to the present invention.
- the long phase difference film cut out to 3 m was wound into a roll shape with a minimum diameter of 31 mm and stored at 23 ° C for 1 month.
- the surface of the retardation film did not change before and after storage, cracks were not generated, and adhesion between the films was strong.
- a photopolymerizable liquid crystal compound (the above compound (1)) is added to cyclohexano 20 mass 0/0 dissolved in emissions, uniaxial stretching COP (cyclo O Les fins polymer) film (JSR Co., Ltd., trade name: ARTON) for coating as coating amount is 3 g / m 2 by a bar coating did.
- the solvent was removed by heating at 50 ° C. for 2 minutes.
- the photopolymerizable liquid crystal compound was fixed by irradiating the coated surface with ultraviolet rays, and the residual solvent was removed by heating at 90 ° C. for 2 minutes to prepare a retardation film.
- the obtained retardation film was used as a sample and evaluated according to the following items.
- the phase difference of the sample was measured by an automatic birefringence measuring apparatus (manufactured by Oji Scientific Instruments, trade name: KOBRA-21ADH). Anisotropy that increases the phase difference of the substrate film was confirmed from the chart of the optical phase difference and the incident angle of the measurement light when the measurement light was perpendicularly or obliquely incident on the sample surface.
- the three-dimensional refractive index was measured with the same measuring device. The results are shown in Table 2.
- Figure 16 shows the results of observing the cross section of the sample with SEM. As is clear from FIG. 16, there is no boundary between the retardation enhancement region and the polymer film in the sample, and the liquid crystal compound penetrated into the polymer film by combining the measurement results of the above retardation. It was judged.
- the haze value was measured by the same method as in Example 1. As a result, it was good at 0.3% or less.
- the wet heat resistance test was conducted in the same manner as in the wet heat resistance test-1 in Example 1. As a result, there was no change in optical properties and adhesion before and after the test.
- Example 2 A water resistance test was conducted in the same manner as in Example 1. As a result, there was no change in optical properties and adhesion before and after the test.
- Example 9 An unstretched COP film manufactured by CFSR Co., Ltd. (trade name: ARTON) was used to produce a retardation film in the same manner as in Example 9. As a result of the same evaluation as in Example 9, the same results as in Example 9 were obtained except that the optical characteristics (three-dimensional refractive index) were as shown in Table 3.
- the retardation film of the present invention can be used for optical functional films such as an optical compensator (for example, a viewing angle compensator), an elliptically polarizing plate, and a brightness enhancement plate.
- FIG. 1 is a schematic cross-sectional view showing an example of a retardation film of the present invention.
- FIG. 2 is a schematic cross-sectional view showing another example of the retardation film of the present invention.
- FIG. 3 is a diagram schematically showing the distribution of concentration gradient.
- FIG. 4 is a schematic cross-sectional view showing an example of the retardation film of the present invention.
- FIG. 5 is a schematic cross-sectional view showing another example of the retardation film of the present invention.
- FIG. 6 is a process diagram showing an example of a method for producing a retardation film of the present invention.
- FIG. 7 is a schematic exploded perspective view showing an example of a liquid crystal display device provided with the retardation film of the present invention.
- FIG. 8 is a schematic exploded perspective view showing an example of a liquid crystal display device provided with the optical functional film of the present invention.
- FIG. 9 is a schematic exploded perspective view showing an example of a liquid crystal display device provided with the polarizing film of the present invention.
- FIG. 10 is an SEM photograph showing a cross section of the retardation film of Example 1.
- FIG. 11 is a TEM photograph showing a cross section of the retardation film of Example 1.
- FIG. 12 is a graph showing the concentration distribution of the retardation film of Example 1 measured by a positive secondary ion spectrum in TOF-SIMS measurement.
- FIG. 13 is a diagram showing a concentration distribution of the retardation film of Example 1 measured by a negative secondary ion spectrum in TOF-SIMS measurement.
- FIG. 14 is a graph showing the relationship between the coating amount and the phase difference in Example 5.
- FIG. 15 is a view showing the retardation angle dependence of the retardation films of Example 6 and Example 7.
- FIG. 16 is an SEM photograph showing a cross section of the retardation film of Example 9.
- FIG. 17 is a schematic exploded perspective view showing a conventional liquid crystal display device.
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Abstract
Description
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KR1020107002155A KR101271988B1 (ko) | 2004-09-10 | 2005-09-09 | 위상차 필름 및 그의 제조 방법, 광학 기능 필름, 편광 필름, 및 표시 장치 |
KR1020077008052A KR101144410B1 (ko) | 2004-09-10 | 2005-09-09 | 위상차 필름 및 그의 제조 방법, 광학 기능 필름, 편광필름, 및 표시 장치 |
EP05782351A EP1793246B1 (en) | 2004-09-10 | 2005-09-09 | Polymeric optical retardation film infiltrated with anisotropic liquid crystal material, optical functional film, polarizing film and display apparatus |
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JP2008009345A (ja) * | 2006-06-30 | 2008-01-17 | Dainippon Printing Co Ltd | 位相差フィルム |
JP2008033242A (ja) * | 2006-06-30 | 2008-02-14 | Dainippon Printing Co Ltd | 位相差部材及びその製造方法 |
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US20060105115A1 (en) | 2004-11-16 | 2006-05-18 | Keiji Kashima | Retardation film and method for producing the same, optical functional film, polarizing film, and display device |
JP5218411B2 (ja) * | 2007-09-06 | 2013-06-26 | コニカミノルタアドバンストレイヤー株式会社 | 光学フィルム、偏光板及び液晶表示装置 |
KR101222058B1 (ko) * | 2008-02-27 | 2013-01-15 | 주식회사 엘지화학 | 정의 두께 방향 위상차를 갖는 위상차 필름, 이의제조방법, 및 이를 포함하는 액정 표시 장치 |
GB0816836D0 (en) | 2008-09-15 | 2008-10-22 | Element Six Holding Gmbh | Steel wear part with hard facing |
KR101137118B1 (ko) * | 2008-12-24 | 2012-04-19 | 주식회사 엘지화학 | 위상차 필름, 이를 포함하는 편광판 및 액정 표시 장치 |
WO2017057545A1 (ja) * | 2015-09-30 | 2017-04-06 | 富士フイルム株式会社 | 光学フィルム、偏光板および画像表示装置 |
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- 2005-09-09 KR KR1020107002155A patent/KR101271988B1/ko active IP Right Grant
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JP2008033242A (ja) * | 2006-06-30 | 2008-02-14 | Dainippon Printing Co Ltd | 位相差部材及びその製造方法 |
Also Published As
Publication number | Publication date |
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KR101271988B1 (ko) | 2013-06-05 |
TWI388886B (zh) | 2013-03-11 |
JP2008282027A (ja) | 2008-11-20 |
JP2012022339A (ja) | 2012-02-02 |
EP2237085A3 (en) | 2011-04-20 |
JP2012083761A (ja) | 2012-04-26 |
JP5163799B2 (ja) | 2013-03-13 |
KR101144410B1 (ko) | 2012-05-11 |
EP2237085B1 (en) | 2013-01-02 |
TW200619686A (en) | 2006-06-16 |
EP1793246B1 (en) | 2013-03-13 |
JP4883049B2 (ja) | 2012-02-22 |
EP2237085A2 (en) | 2010-10-06 |
JP5163802B2 (ja) | 2013-03-13 |
EP1793246A1 (en) | 2007-06-06 |
KR20100027244A (ko) | 2010-03-10 |
EP1793246A4 (en) | 2009-08-26 |
KR20070108849A (ko) | 2007-11-13 |
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