JP2006011281A - Polarizing filter and polarizing sunglasses - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing filter capable of improving visibility by intercepting reflected light from the surface of a reflector, regardless of the angle of the disposition of the reflector, such as glass or water surface. <P>SOLUTION: The polarizing filter has the function of transmitting the circularly polarized light with respect to the incident light in the direction of normal line, whereas has the function of reflecting the linearly polarized light with respect to the incident light in oblique direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polarizing filter. The polarizing filter of the present invention can be applied to various uses. For example, it can be suitably applied as a polarizing filter for lenses such as polarizing sunglasses, cameras, telescopes, and glasses.

  Conventionally, polarizing filters have been widely used. Since the surface reflected light of the water surface and glass is linearly polarized, the surface reflected light is cut by arranging a polarizing filter (polarizing element) so that the linearly polarized light in the direction orthogonal to these polarization directions is transmitted. Products under the fish and display glass on the bottom can be easily seen. These matters are known techniques for a long time (Non-Patent Document 1). This is because the reflectance depending on the vibration direction of the reflected light differs depending on the incident angle.

  For example, a light ray incident on and reflected by the water surface becomes linearly polarized light (S-polarized light) that vibrates perpendicularly to the incident surface when the incident angle with respect to the normal direction of the water surface is about 53 degrees. The S-polarized light at this time has a reflectance of about 7.7%, and this significantly reduces the visibility of the object under the surface of the water. Therefore, when P-polarized light having an axis orthogonal to the S-polarized light is incident at this angle, the reflectance becomes 0%. In the polarizing filter, a polarizing element is generally used in the axial direction that effectively cuts this S-polarized light.

  On the other hand, in the case of a showcase surrounded by glass and the like, unlike the water surface, the glass surface is installed in a direction perpendicular to the viewing direction, so the optimum installation angle of the polarizing filter is different from the water surface. Therefore, the polarizing filter used when visually recognizing the water surface cannot be used as it is. This is because, in a showcase or the like, there is a case where the viewer looks in from the top, bottom, left, and right, and the axial direction of the polarizer used for the optimum polarizing filter is different.

  Furthermore, image display devices such as a liquid crystal display device using a polarizing plate on the surface have become widespread with the spread of notebook computers, PDAs, and mobile phones in recent years. The light emitted from these image display devices has high linear polarization, and there has been a problem that the amount of light is reduced more than necessary in polarized sunglasses using a polarizing filter. This problem occurs not only in the direct-view type liquid crystal display device but also in a projection type liquid crystal display device and a CRT, an organic EL, a PDP, etc. in which a polarizer is disposed to prevent surface reflection. In order to solve this problem, there is an attempt to align the linearly polarized light of the output light of the image display device and the polarization axis of the polarized sunglasses. However, when the polarization axes are not aligned due to the difference in the direction of the polarization axis depending on the type of the image display device, and because the viewer tilts his / her neck, the influence on the decrease in visibility is inevitable.

For example, there has been proposed an image display device that hardly affects the visibility even when wearing polarized sunglasses (see Patent Document 1 and Patent Document 2). However, these patent documents do not solve the above problems. Further, it has been proposed that linearly polarized light is changed from elliptically polarized light to circularly polarized light by providing a retardation layer on the outer side (viewing side) of the polarizing plate of the image display device (see Patent Document 3). However, in this patent document, there is a drawback that the shielding factor for each wavelength changes and looks colored unless a broadband retardation plate is used. Further, in recent years when color display has become a standard, it has not been sufficient for suppressing color change.
W. A. Shercliffe, "Polarized light and its application, page 133" (published by Kyoritsu Publishing Co., Ltd. 1965.9.05) etc. JP 2000-292882 A JP 2004-6248 A JP 2002-350821 A

  An object of this invention is to provide the polarizing filter which can interrupt | block the surface reflected light of a reflector, and can improve visibility irrespective of the arrangement | positioning angle with respect to reflectors, such as glass and a water surface.

  Another object of the present invention is to provide polarized sunglasses using the polarizing filter.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the following polarizing filter, and have completed the present invention.

  That is, the present invention has a function of transmitting circularly polarized light with respect to incident light in the normal direction, and having a function of reflecting linearly polarized light with respect to incident light in the oblique direction, About.

  For the polarizing filter, a polarizing element having a function of transmitting circularly polarized light with respect to incident light in the normal direction and a function of reflecting linearly polarized light with respect to incident light in the oblique direction is preferably used. .

  The polarizing filter has a function of transmitting circularly polarized light with respect to incident light in the normal direction, and reflects linearly polarized light with respect to incident light in an oblique direction with an incident angle of 30 ° or more with respect to the normal direction. A polarizing element having a function is preferably used.

  As the polarizing element used for the polarizing filter, a reflective polarizer formed of a cholesteric liquid crystal layer having polarization separation characteristics and emitting incident light after being polarized and separated can be suitably used.

  In general, a reflective polarizer using a cholesteric liquid crystal separates circularly polarized light by selective reflection characteristics resulting from the twist pitch of the cholesteric liquid crystal. A cholesteric liquid crystal reflects one circularly polarized light and transmits the other. It is known that obliquely incident light is elliptically polarized as shown in US Pat. No. 5,731,886 and US Pat. No. 6,630,974. In the present invention, it has been found that by carefully controlling the pitch change and thickness of the cholesteric liquid crystal layer, linear polarization progresses as the incident angle increases, and the linear polarization increases particularly in the region where the incident angle is 30 ° or more. A reflective polarizer using such a cholesteric liquid crystal is used as a polarizing element of a polarizing filter. The cholesteric liquid crystal can control the axial direction of polarization by controlling the pitch change and thickness. If the pitch change and thickness of the cholesteric liquid crystal layer are carefully controlled, it is possible to improve the linear polarization characteristics in the region where the incident angle is 30 ° or more and to arbitrarily control the polarization axis direction.

  The polarizing filter of the present invention functions as a circularly polarizing plate for incident light in the front direction (normal direction). Therefore, when this polarizing filter is used for sunglasses, the visibility of an image display device having a polarizing plate is not impaired. Further, it has a function of reflecting linearly polarized light with respect to obliquely incident light. Therefore, when the line of sight is shifted and the object is viewed from an oblique direction, the reflection axis of the linearly polarized light in the polarizing filter is aligned with the polarization axis of the surface reflected light (linearly polarized light), thereby blocking the incidence of the surface reflected light. be able to. It is preferable to have a function of reflecting linearly polarized light with respect to incident light in an oblique direction at an angle of 30 ° or more from the front direction. In the present invention, linearly polarized light means a case where the distortion rate of elliptically polarized light is 0.2 or less. From the viewpoint of linear polarization, the distortion rate is preferably 0.1 or less. The circularly polarized light is a case where the elliptically polarized light has a distortion rate of 0.7 or more. From the viewpoint of circularly polarized light, the distortion rate is preferably 0.9 or more.

  For example, as shown in FIG. 8, when the water surface (W1) is viewed, the shape is often looked down, and the visibility is likely to deteriorate due to the influence of reflected light from the water surface (r1: S-polarized light is large). Since the polarizing filter F of the invention has a reflection function with respect to linearly polarized light that is obliquely incident, the reflected light (r1) from the water surface can be reflected. On the other hand, the linearly polarized light (r2) orthogonal to the reflected light (r1) passes through the polarization filter F. Therefore, according to the polarizing filter F of the present invention, it is possible to remove the reduction in visual recognition due to the reflected light (r1) and improve the visibility of an object in water. In the front direction, circularly polarized light (r3) is transmitted through the polarizing filter F, and visibility can be secured.

  In addition, a case where a product is viewed through a window glass such as a vertically arranged show window (W2) will be described as an example. When a glass plate is present on the left side as shown in FIG. 9 (A), it was difficult to see the product for visually recognizing surface reflection at a shallow angle, but the polarizing filter F of the present invention. Has a reflection function for obliquely incident linearly polarized light, and can therefore reflect the reflected light (r1) from the glass plate. On the other hand, the linearly polarized light (r2) orthogonal to the reflected light (r1) passes through the polarization filter F. Therefore, according to the polarizing filter F of this invention, the visual fall by reflected light (r1) can be removed, and the visibility of goods through a window glass can be improved. Further, the polarizing filter F of the present invention can change the transmission axis direction of polarized light only by moving the viewpoint, so that it is not necessary to provide a special rotating structure. Further, as shown in FIG. 9B, surface reflection can be blocked in the same manner as the water surface described above when looking down from the show window (W2).

  Thus, the polarizing filter of the present invention can efficiently cut surface reflection with respect to an arbitrary incident direction. 8 and 9 exemplify the case where the arrangement angle of the polarizing filter F with respect to the reflector such as the water surface (W1) and the glass (W2) is 90 ° and 0 °. In (for example, polarized sunglasses), the direction in which good surface reflection cut characteristics can be obtained only by moving the viewpoint can be designated, so that the flexibility in use is high and the utility is high.

  When the polarizing filter F is used for visual recognition of a liquid crystal display device (LCD) as shown in FIG. 10, the front direction of the polarizing filter F is transparent to circularly polarized light (r3), so that the visibility is not affected. Accordingly, the same polarizing filter F can be used to effectively block the surface reflected light (linearly polarized light) when the water surface is visible.

  As the reflective polarizer, the outgoing light with respect to the incident light in the normal direction has a distortion rate of 0.5 or more, and the outgoing light with respect to the incident light incident with an inclination of 60 ° or more from the normal direction has a distortion rate of 0. .2 or less, and the linearly polarized light component of the emitted light increases as the incident angle increases.

  In the reflective polarizer, the outgoing light with respect to the incident light in the normal direction has a distortion rate of 0.5 or more, and circularly polarized light is emitted at the normal incident light or at an incident angle close to the normal incident. Since the ratio of circularly polarized light increases as the distortion rate of outgoing light with respect to incident light in the normal direction increases, it is preferably 0.7 or higher, and more preferably 0.9 or higher. On the other hand, the outgoing light with respect to the incident light inclined at an angle of 60 ° or more from the normal direction has a distortion rate of 0.2 or less, and linearly polarized light is emitted at a deep incident angle. Since the ratio of linearly polarized light increases as the distortion rate of the outgoing light with respect to the incident light incident with an inclination of 60 ° or more from the normal direction, it is preferably 0.1 or less.

  Such a reflective polarizer has a function of transmitting circularly polarized light with respect to incident light in the normal direction, and with respect to incident light in the oblique direction, the linearly polarized light component of the emitted light increases as the incident angle increases. Has increasing features. For obliquely incident light of 30 ° or more, since it functions as a linearly polarized reflective polarizer, when the polarization axis of the surface reflected light (linearly polarized light) and the polarization axis of the reflective polarizer are orthogonal, Visibility can be improved by blocking the surface reflected light. As shown in FIGS. 1 and 2, since the reflection polarizer has a different transmission axis direction of polarized light with respect to obliquely incident light, the polarization filter using the reflection polarizer transmits polarized light only by moving the viewpoint. This is preferable in that the axial direction can be easily changed.

  As the reflective polarizer, the linearly polarized light component of the emitted light that increases as the incident angle increases can be exemplified by a linearly polarized light axis substantially perpendicular to the normal direction of the reflective polarizer surface. . In FIG. 1A, the outgoing light (e) transmitted through the reflective polarizer (A1) which is the optical surface (x-axis-y-axis plane) has different polarization components depending on the incident angle of the incident light (i). It is a conceptual diagram which shows that. FIG. 1B is a conceptual diagram when the emitted light (e) is viewed from the z-axis direction. Note that, as shown in FIG. 3, (i) linearly polarized light, (ii) natural light, (iii) circularly polarized light, and (iv) elliptically polarized light.

  Emission light (e1): Emission light with respect to incident light (i1) in the z-axis direction (normal direction) with respect to the reflective polarizer (A1), which is circularly polarized light.

  Outgoing light (e2), (e4): Outgoing light with respect to incident light (i2), (i4) obliquely incident on the reflective polarizer (A1), and elliptically polarized light. The outgoing light (e2) is elliptically polarized light that exists on a plane including the z axis and the y axis and has an axis orthogonal to the plane. The outgoing light (e4) is elliptically polarized light that exists on a plane including the z-axis and the x-axis and has an axis orthogonal to the plane.

  Outgoing light (e3), (e5): outgoing light with respect to incident light (i3), (i5) obliquely incident on the reflective polarizer (A1) at a large angle, and linearly polarized light. The outgoing light (e3) is linearly polarized light that exists on a plane including the z-axis and the y-axis and has an axis orthogonal to the plane. The outgoing light (e5) is linearly polarized light that exists on a plane including the z-axis and the x-axis and has an axis orthogonal to the plane. Thus, the outgoing lights (e3) and (e5), which are linearly polarized light, have their polarization axes substantially perpendicular to the z-axis, that is, parallel to the optical surface (x-axis-y-axis plane). Yes.

  Further, as the polarizing element, the linearly polarized light component of the emitted light that increases as the incident angle increases can be exemplified by a linearly polarized light polarization axis substantially parallel to the normal direction of the polarizing element surface. . In FIG. 2A, the outgoing light (e) transmitted through the reflective polarizer (A2), which is an optical surface (x-axis-y-axis plane), has different polarization components depending on the incident angle of the incident light (i). It is a conceptual diagram which shows that. FIG. 2B is a conceptual diagram when the emitted light (e) is viewed from the z-axis direction.

  Emission light (e41): Emission light with respect to incident light (i41) in the z-axis direction (normal direction) with respect to the reflective polarizer (A2), and is circularly polarized light.

  Emission light (e42), (e44): Emission light with respect to incident light (i42), (i44) obliquely incident on the reflective polarizer (A2), and elliptically polarized light. The outgoing light (e42) is elliptically polarized light that exists on a plane including the z-axis and the y-axis and has an axis parallel to the plane. The outgoing light (e44) is elliptically polarized light that exists on a plane including the z-axis and the x-axis and has an axis parallel to the plane.

  Outgoing light (e43), (e45): outgoing light with respect to incident light (i43), (i45) obliquely incident on the reflective polarizer (A2) at a large angle and linearly polarized light. The outgoing light (e43) is linearly polarized light that exists on a plane including the z-axis and the y-axis and has an axis parallel to the plane. The outgoing light (e45) is linearly polarized light that exists on a plane including the z-axis and the x-axis and has an axis parallel to the plane. Thus, the outgoing lights (e43) and (e45) that are linearly polarized light have their polarization axes substantially parallel to the z axis, that is, orthogonal to the optical surface (x axis-y axis plane). Yes.

  The reflective polarizer preferably has a reflection bandwidth of 200 nm or more. Conventionally, a cholesteric liquid crystal layer is supposed to transmit / reflect circularly polarized light regardless of the incident angle. See FIG. In fact, until now, in the single-pitch narrow-band cholesteric liquid crystal layer (a1), the emitted light has been circularly polarized regardless of the incident angle of the incident light. In the present invention, the cholesteric liquid crystal layer having a broadband selective reflection wavelength band has found a phenomenon of transmitting linearly polarized light when the incident angle of incident light is large as described above. That is, this phenomenon is not obtained in a single pitch cholesteric liquid crystal layer having a selective reflection function only at a specific wavelength, but is obtained only in a cholesteric liquid crystal layer in which the pitch length is changed over a wide band.

  In the past, when a cholesteric liquid crystal layer having a large birefringence was oriented thickly to several tens of μm by Takezoe (Jpn. J. Appl. Phys., 22, 1080 (1983)) It has been reported that incident light having a large angle is totally reflected and cannot be transmitted. See FIG. However, this document does not describe that incident light having a large incident angle is linearly polarized.

  The reflective polarizer (A) having the above phenomenon can be obtained, for example, by forming a cholesteric liquid crystal layer having a selective reflection wavelength band covering the entire visible light region by stacking cholesteric liquid crystal layers having different center wavelengths. . See FIG. FIG. 6 shows a case where three layers of R (red wavelength region), G (green wavelength region), and B (blue wavelength region) are stacked. In addition, a cholesteric liquid crystal layer having a wider band by changing the twist pitch length in the thickness direction can be used. See FIG. Thus, the polarizing element having the above phenomenon may be a laminated product of cholesteric liquid crystal layers having a plurality of different selective reflection wavelength bands as shown in FIG. 6, and the pitch length is continuous in the thickness direction as shown in FIG. Any of the changing cholesteric liquid crystal layers can be used, and both have the same effect.

  The reason why the above phenomenon occurs is not clear, but if it is simply polarization separation based on the Brewster angle at the interface of the liquid crystal layer, a linearly polarized light should be generated for a specific wavelength even in a single pitch cholesteric liquid crystal layer. Further, since there is no difference between the cholesteric liquid crystal layer laminate and the cholesteric liquid crystal layer whose pitch length continuously changes in the thickness direction, it is clear that there is no reflection effect due to the lamination interface. Therefore, it can be considered that the above phenomenon is that the cholesteric liquid crystal layer having a different wavelength band imparts a phase difference to the circularly polarized light separated when transmitted through the cholesteric liquid crystal layer and linearly polarized.

  In order for the above phenomenon to function effectively, a sufficiently wide selective reflection bandwidth is required, preferably 200 nm or more, more preferably 300 nm or more, and even more preferably 400 nm or more. Specifically, in order to cover the visible light region, it is necessary to cover the range of 400 to 600 nm. Since the selective reflection wavelength shifts to the short wavelength side according to the incident angle, the extended selective reflection wavelength band should be extended to the long wavelength side to cover the visible light range regardless of the incident angle. However, it is not limited to this.

  The polarizing filter is preferably provided so that the reflection axis direction of the linearly polarized light with respect to the obliquely incident light in the polarizing filter is a direction that reflects the obliquely reflected light from the water surface and prevents transmission. . With this arrangement, surface reflection from the water surface can be suitably blocked, and visibility can be improved.

  The polarizing filter can be provided with at least one layer selected from a hard coat layer, a stain-proof layer and a water-repellent treatment layer.

  The present invention also relates to a polarized sunglasses characterized in that the polarizing filter is used. As described with reference to FIG. 10, when the polarizing filter F is used for polarized sunglasses, it can be used without affecting the visual recognition of the liquid crystal display device, and the reflected light from the oblique direction of the reflector such as the water surface can be used. It can be effectively blocked.

  In the polarized sunglasses, it is preferable that a light-absorbing semi-transmissive layer is provided on the eye side of the polarizing filter.

  When the polarizing filter of the present invention is used for sunglasses, when the incident angle-dependent reflective polarizer is used as the polarizing filter F, as shown in FIG. There is a possibility that the light (r4) is reflected, enters the eye, and hinders visibility. This is because the reflective polarizer used is reflective and has high reflectivity. In order to prevent such a decrease in visibility, it is preferable to dispose the light-absorbing semi-transmissive layer E closer to the eye side than the polarizing filter F in the polarized sunglasses as shown in FIG. By providing the light-absorbing semi-transmissive layer E, the incident light (r4) from the periphery (side, rear) of the eye is reflected twice by the reflective polarizer and viewed through the light-absorbing semi-transmissive layer E twice. This is because the reflected light decreases with the square of the extinction coefficient because it must be transmitted.

  An absorptive polarizer can be provided as the light-absorbing semi-transmissive layer. When an absorptive linear polarizer is used as the light-absorbing semi-transmissive layer, half of the circularly polarized light is transmitted in the front direction due to its property, but light in an oblique direction is not transmitted at all in the axial direction, and in the orthogonal direction. It is possible to impart a transmitting characteristic. An absorptive circular polarizer can also be used as the light-absorbing semi-transmissive layer. In this case, the front direction uses a light transmitting in the same direction as the incident angle dependent reflective polarizer. The viewing angle anisotropy in this case conforms to the value of the incident angle dependent polarizing element itself.

  The polarizing filter of the present invention has a function of transmitting circularly polarized light with respect to incident light in the normal direction, and a filter having a function of reflecting linearly polarized light with respect to incident light in the oblique direction is used without particular limitation. However, a polarizing element having this function is preferably used.

  As such a polarizing element, as described above, a reflective polarizer formed by a cholesteric liquid crystal layer having a reflection bandwidth of 200 nm or more is suitable. The cholesteric liquid crystal layer can be formed by stacking cholesteric liquid crystal layers having a plurality of different selective reflection wavelength bands. Further, a cholesteric liquid crystal layer whose pitch length continuously changes in the thickness direction can be used. In order to control the emitted light as shown by the reflective polarizer (A1) in FIG. 1 or the reflective polarizer (A2) in FIG. 2 (control the direction of the polarization axis of the obliquely emitted light), a cholesteric liquid crystal layer is appropriately used. Select to do.

(Laminated cholesteric liquid crystal layer)
When the reflective polarizer is a laminate of cholesteric liquid crystal layers having a plurality of different selective reflection wavelength bands, each cholesteric liquid crystal layer has a plurality of cholesteric liquid crystals appropriately so that the reflection bandwidth of the laminate is 200 nm or more. Select layers and stack.

  A suitable cholesteric liquid crystal layer may be used without any particular limitation. For example, a liquid crystal polymer exhibiting cholesteric liquid crystallinity at high temperature, a polymerizable liquid crystal obtained by polymerizing a liquid crystal monomer and, if necessary, a chiral agent and an alignment aid by irradiation with ionizing radiation such as an electron beam or ultraviolet rays or heat, A mixture etc. are mention | raise | lifted. The liquid crystallinity may be either lyotropic or thermotropic, but is preferably a thermotropic liquid crystal from the viewpoint of ease of control and ease of formation of a monodomain.

  The cholesteric liquid crystal layer can be formed by a method according to a conventional alignment process. For example, rayon is formed by forming a film of polyimide, polyvinyl alcohol, polyester, polyarylate, polyamide imide, polyether imide, etc. on a support substrate having a birefringence retardation as small as possible such as triacetyl cellulose or amorphous polyolefin. An alignment film rubbed with a cloth or the like, an obliquely deposited layer of SiO, or a substrate using the surface properties of a stretched substrate such as polyethylene terephthalate or polyethylene naphthalate as an alignment film, or the above substrate surface is rubbed or bentara A substrate that has been processed with a fine polishing agent represented by the above and formed fine irregularities having fine alignment regulating force on the surface, or an alignment film that generates liquid crystal regulating force by light irradiation such as an azobenzene compound on the substrate film A liquid crystal polymer is applied on a suitable alignment film composed of a base material formed with Open and heat to above the glass transition temperature and below the isotropic phase transition temperature, and in a state where the liquid crystal polymer molecules are in a planar orientation, cool to below the glass transition temperature to form a solidified layer in which the orientation is fixed And how to do it. Further, the structure may be fixed by irradiation of energy such as ultraviolet rays or ion beams at the stage where the alignment state is formed.

  The liquid crystal polymer film is formed by, for example, thinning a solution of a liquid crystal polymer in a solvent by spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, or gravure printing. It can be carried out by a method of developing a layer and drying it as necessary. Examples of the solvent include chlorinated solvents such as methylene chloride, trichloroethylene, and tetrachloroethane; ketone-based solvents such as acetone, methyl ethyl ketone, and cyclohexanone; aromatic solvents such as toluene; cyclic alkanes such as cycloheptane; or N -Methyl pyrrolidone, tetrahydrofuran, etc. can be used suitably.

  In addition, a heating melt of a liquid crystal polymer, preferably a heating melt exhibiting an isotropic phase, is developed according to the above, and a thin layer is further developed and solidified while maintaining the melting temperature as necessary. can do. This method is a method that does not use a solvent. Therefore, the liquid crystal polymer can be developed even by a method that provides good hygiene in the working environment.

  In developing the liquid crystal polymer or the like, a method of superimposing a cholesteric liquid crystal layer through an alignment film may be employed as necessary for the purpose of reducing the thickness. The cholesteric liquid crystal layer thus obtained can be used without being peeled off from the support substrate / alignment substrate used at the time of film formation and transferred to another optical material.

  Cholesteric liquid crystal layer stacking methods include the method of laminating a plurality of individually produced cholesteric liquid crystal layers with an adhesive or adhesive, the method of crimping after swelling or dissolving the surface with a solvent, etc., heat, ultrasonic waves, etc. The crimping method is given while adding. Moreover, after producing a cholesteric liquid crystal layer, methods, such as overlaying the cholesteric liquid crystal layer which has another selective reflection center wavelength on this layer, can be used.

(Production method of cholesteric liquid crystal layer covering visible light wavelength range)
Examples of a method for producing a cholesteric liquid crystal layer covering the visible light wavelength range include a method of irradiating the composition with an ionizing radiation such as an electron beam or an ultraviolet ray by the following method using a composition containing the same liquid crystal monomer as described above. . For example, a method using a difference in polymerization rate due to a difference in ultraviolet transmittance in the thickness direction (Japanese Patent Laid-Open No. 2000-95883), a method of forming a concentration difference in the thickness direction by extraction with a solvent (Japanese Patent No. 3062150) And a method of performing the second polymerization by changing the temperature after the first polymerization (US Pat. No. 6,057,008) and the like.

  In addition, a step of applying a liquid crystal mixture containing a polymerizable mesogenic compound (a) and a polymerizable chiral agent (b) to an alignment substrate, and a state in which the liquid crystal mixture is in contact with a gas containing oxygen from the substrate side A method of performing a polymerization and curing step by irradiating with ultraviolet rays, and increasing the difference in polymerization rate in the thickness direction due to inhibition of oxygen polymerization by irradiating ultraviolet rays from the substrate side (Japanese Patent Laid-Open No. 2000-139953) is preferably used. It is done.

  Regarding the method described in JP-A-2000-13953, a cholesteric liquid crystal layer having a wider reflection wavelength band can be obtained by the following method.

For example, in the ultraviolet polymerization step, the liquid crystal mixture is in contact with a gas containing oxygen at an ultraviolet irradiation intensity of 20 to 200 mW / cm ² at a temperature of 20 ° C. or higher for 0.2 to 5 seconds. The step (1) of irradiating ultraviolet rays from the alignment substrate side, the step (2) of heating the liquid crystal layer at 70 to 120 ° C. for 2 seconds or more in a state where the liquid crystal layer is in contact with the gas containing oxygen, and then In the state in which the liquid crystal layer is in contact with a gas containing oxygen, the step of irradiating with ultraviolet rays from the alignment substrate side at a temperature of 20 ° C. or higher and lower than the step (1) for 10 seconds or more. (3) Next, there is a method performed by the step (4) of irradiating ultraviolet rays in the absence of oxygen (Japanese Patent Application No. 2003-93963).

Further, in the ultraviolet polymerization step, the liquid crystal mixture is in contact with a gas containing oxygen, at a temperature of 20 ° C. or higher, an ultraviolet irradiation intensity of 1 to 200 mW / cm ² and a range of 0.2 to 30 seconds. Step (1) of irradiating ultraviolet rays from the alignment substrate side three times or more while lowering the ultraviolet irradiation intensity and lengthening the ultraviolet irradiation time each time the number of times of ultraviolet irradiation increases, and then in the absence of oxygen Then, there is a method performed by the step (2) of irradiating with ultraviolet rays (Japanese Patent Application No. 2003-94307).

Further, the ultraviolet polymerization step is carried out for 0.2 to 5 seconds at an ultraviolet irradiation intensity of 20 to 200 mW / cm ² at a temperature of 20 ° C. or higher in a state where the liquid crystal mixture is in contact with a gas containing oxygen. Step (1) of irradiating ultraviolet rays from the alignment substrate side, and then in a state where the liquid crystal layer is in contact with a gas containing oxygen, until it reaches a temperature higher than Step (1) and 60 ° C. or higher, A step (2) of irradiating with ultraviolet rays from the alignment substrate side for 10 seconds or more at a temperature rising rate of 2 ° C./second or lower with an ultraviolet irradiation intensity lower than that in step (1), and then irradiating with ultraviolet rays in the absence of oxygen. An example is a method performed in the step (3) (Japanese Patent Application No. 2003-94605).

  Furthermore, the following method can be used. In the following method, a cholesteric liquid crystal layer having a wide reflection wavelength band and good heat resistance can be obtained. For example, there is a method in which a liquid crystal mixture containing a polymerizable mesogenic compound (a), a polymerizable chiral agent (b) and a photopolymerization initiator (c) is subjected to ultraviolet polymerization between two substrates (Japanese Patent Application 2003). No. 4346, Japanese Patent Application No. 2003-4101). Further, there is a method in which a polymerizable ultraviolet absorber (d) is further added to the liquid crystal mixture and ultraviolet polymerization is carried out between two substrates (Japanese Patent Application No. 2003-4298). Also, a method of applying a liquid crystal mixture containing a polymerizable mesogenic compound (a), a polymerizable chiral agent (b), and a photopolymerization initiator (c) on an alignment substrate and subjecting it to ultraviolet polymerization in an inert gas atmosphere (Japanese Patent Application No. 2003-4406).

The ultraviolet polymerization step is performed for 0.1 to 5 seconds at a temperature of 70 ° C. or higher and an ultraviolet irradiation intensity of 10 to 200 mW / cm ^{2 in} a state where the liquid crystal mixture is in contact with a gas containing oxygen. , Ultraviolet ray irradiation (1), and then a step (2) of heat treatment at 70 ° C. or higher for 0.1 to 5 seconds in a state where the liquid crystal layer is in contact with a gas containing oxygen, After step (1) and step (2), the step can be carried out by step (3) of irradiating with ultraviolet rays in the absence of oxygen. Preferably, the step (1) and the step (2) are repeated a plurality of times, and then the step (3) of ultraviolet irradiation is performed (Japanese Patent Application No. 2004-71158).

Further, in the ultraviolet polymerization step, the liquid crystal mixture is in contact with a gas containing oxygen at an ultraviolet irradiation intensity of 10 to 200 mW / cm ² at a temperature of 70 ° C. or higher for 0.01 to 5 seconds. , Ultraviolet irradiation step (1), and then the step (2) of heat-treating at 70 ° C. or more for a time exceeding 5 seconds in a state where the liquid crystal layer is in contact with a gas containing oxygen. After step 1) and step (2), the step can be performed by step (3) of irradiating ultraviolet rays in the absence of oxygen. Preferably, the step (1) and the step (2) are repeated a plurality of times, and then the step (3) of ultraviolet irradiation is performed (Japanese Patent Application No. 2004-168666).

  In addition, as a manufacturing method of a polarizing element (A2), the method of the said Japanese Patent Application No. 2003-93963 is preferable.

  The polymerizable mesogenic compound (a), polymerizable chiral agent (b) and the like that form the cholesteric liquid crystal layer will be described below. These materials are cholesteric liquid crystal layers whose pitch length is continuously changed in the thickness direction, and cholesteric to form a laminate. Any liquid crystal layer can be used.

  As the polymerizable mesogenic compound (a), those having at least one polymerizable functional group and having a mesogenic group composed of a cyclic unit or the like are preferably used. Examples of the polymerizable functional group include an acryloyl group, a methacryloyl group, an epoxy group, and a vinyl ether group. Among these, an acryloyl group and a methacryloyl group are preferable. Further, by using a compound having two or more polymerizable functional groups, a crosslinked structure can be introduced to improve durability. Examples of the cyclic unit serving as a mesogenic group include biphenyl, phenylbenzoate, phenylcyclohexane, azoxybenzene, azomethine, azobenzene, phenylpyrimidine, diphenylacetylene, diphenylbenzoate, and bicyclohexane. Cyclohexylbenzene, terphenyl and the like. In addition, the terminal of these cyclic units may have substituents, such as a cyano group, an alkyl group, an alkoxy group, a halogen group, for example. The mesogenic group may be bonded via a spacer portion that imparts flexibility. Examples of the spacer portion include a polymethylene chain and a polyoxymethylene chain. The number of repeating structural units forming the spacer portion is appropriately determined depending on the chemical structure of the mesogenic portion, but the repeating unit of the polymethylene chain is 0 to 20, preferably 2 to 12, and the repeating unit of the polyoxymethylene chain is 0 to 0. 10, preferably 1-3.

The molar extinction coefficient of the polymerizable mesogenic compound (a) is 0.1 to 500 dm ³ mol ⁻¹ cm ⁻¹ @ 365 nm, 10 to 30000 dm ³ mol ⁻¹ cm ⁻¹ @ 334 nm, and 1000 to 100,000 dm ^3. it is preferably a mol ^-1 m ^-1 @ 314nm. Those having the molar extinction coefficient have ultraviolet absorbing ability. The molar extinction coefficient is 0.1-50 dm ³ mol ^-1 cm ^-1 @ 365 nm, 50-10000 dm ³ mol ^-1 cm ^-1 @ 334 nm, 10000-50000 dm ³ mol ^-1 cm ^-1 @ 314 nm More preferred. Molar extinction coefficient is ^{0.1~10dm 3 mol -1 cm -1 @ 365nm} , a ^{1000~4000dm 3 mol -1 cm -1 @ 334nm} , at 30000~40000dm ³ mol ^-1 cm ^-1 @ 314nm More preferably. Molar extinction coefficient of ^{0.1dm 3 mol -1 cm -1 @ 365nm} , 10dm 3 mol -1 cm -1 @ 334nm, 1000dm 3 mol -1 cm -1 @ without stick 314nm smaller than sufficient polymerization rate difference It is difficult to increase the bandwidth. On the other ^{hand, 500dm 3 mol -1 cm -1 @} 365nm, 30000dm 3 mol -1 cm -1 @ 334nm, 100000dm 3 mol -1 cm -1 @ If 314nm greater than the polymerization curing to not proceed completely does not end There is. The molar extinction coefficient is a value measured from the absorbance at 365 nm, 334 nm, and 314 nm obtained by measuring the spectrophotometric spectrum of each material.

  The polymerizable mesogenic compound (a) having one polymerizable functional group is, for example, a general formula of the following chemical formula 1:

（式中、Ｒ₁〜Ｒ₁₂は同一でも異なっていてもよく、−Ｆ、−Ｈ、−ＣＨ₃、−Ｃ₂Ｈ₅または−ＯＣＨ₃を示し、Ｒ₁₃は−Ｈまたは−ＣＨ₃を示し、Ｘ₁は一般式（２）：
−（ＣＨ₂ＣＨ₂Ｏ）_a−（ＣＨ₂）_b−（Ｏ）_c−、を示し、Ｘ₂は−ＣＮまたは−Ｆを示す。但し、一般式（２）中のａは０〜３の整数、ｂは０〜１２の整数、ｃは０または１であり、かつａ＝１〜３のときはｂ＝０、ｃ＝０であり、ａ＝０のときはｂ＝１〜１２、ｃ＝０〜１である。）で表される化合物があげられる。

(In the formula, R _{1 to} R ₁₂ may be the same or different and represent —F, —H, —CH ₃ , —C ₂ H ₅ or —OCH ₃ , and R ₁₃ represents —H or —CH ₃ . X ₁ is represented by the general formula (2):
— (CH ₂ CH ₂ O) _a — (CH ₂ ) _b — (O) _c —, and X ₂ represents —CN or —F. In the general formula (2), a is an integer of 0 to 3, b is an integer of 0 to 12, c is 0 or 1, and when a = 1 to 3, b = 0 and c = 0. Yes, when a = 0, b = 1 to 12, and c = 0 to 1. ).

  Specific examples of the polymerizable mesogenic compound (a) include Merck: E7, Wacker Chemical: LC-Silicon-CC3767, BASF: LC242, Takasago International Corporation: L42, and the like.

  Examples of the polymerizable chiral agent (b) include Merck KGaA manufactured by S101, R811, CB15, and BASF manufactured by LC756.

  The amount of the polymerizable chiral agent (b) is preferably about 1 to 20 parts by weight, preferably 3 to 7 parts by weight based on 100 parts by weight of the total of the polymerizable mesogenic compound (a) and the polymerizable chiral agent (b). The part is more suitable. The helical twisting force (HTP) is controlled by the ratio of the polymerizable mesogenic compound (a) and the polymerizable chiral agent (b). By setting the ratio within the above range, the reflection band can be selected so that the reflection spectrum of the obtained cholesteric liquid crystal film can cover the long wavelength region.

  The liquid crystal mixture usually contains a photopolymerization initiator (c). Various kinds of photopolymerization initiators (c) can be used without particular limitation. For example, Irgacure 184, Irgacure 907, Irgacure 369, Irgacure 651, Irgacure 784, Irgacure 814, Darocur 173, Darocur 4205, BASF: TPO (trade name: Lucirin TPO (Lucirin TPO), etc. The blending amount of the agent is preferably about 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the total of the polymerizable mesogenic compound (a) and the polymerizable chiral agent (b). Is preferred.

  As the polymerizable ultraviolet absorber (d), a compound having at least one polymerizable functional group and having an ultraviolet absorbing function can be used without any particular limitation. Specific examples of the polymerizable ultraviolet absorber (d) include RUVA-93 manufactured by Otsuka Chemical Co., and UVA935LH manufactured by BASF. The blending amount of the polymerizable ultraviolet absorber (d) is preferably about 0.01 to 10 parts by weight with respect to a total of 100 parts by weight of the polymerizable mesogenic compound (a) and the polymerizable chiral agent (b). 5 parts by weight is more preferred.

  In order to widen the bandwidth of the resulting cholesteric liquid crystal film, the mixture can be mixed with an ultraviolet absorber to increase the UV exposure intensity difference in the thickness direction. Further, the same effect can be obtained by using a photoreaction initiator having a large molar extinction coefficient.

  The mixture can be used as a solution. Solvents used in preparing the solution are usually halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, phenols such as phenol and parachlorophenol, benzene, toluene, Aromatic hydrocarbons such as xylene, methoxybenzene, 1,2-dimethoxybenzene, others, acetone, methyl ethyl ketone, ethyl acetate, tert-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene bricol monomethyl ether, diethylene glycol Dimethyl ether, ethyl cellosolve, butyl cellosolve, 2-pyrrolidone, N-methyl-2-pyrrolidone, pyridine, triethylamine, te Rahidorofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, can be used acetonitrile, butyronitrile, carbon disulfide, cyclopentanone, cyclohexanone and the like. The solvent to be used is not particularly limited, but methyl ethyl ketone, cyclohexanone, cyclopentanone and the like are preferable. Although the concentration of the solution depends on the solubility of the thermotropic liquid crystalline compound and the final film thickness of the cholesteric liquid crystal film, it cannot be generally stated, but it is usually preferably about 3 to 50% by weight.

  It should be noted that the exemplified alignment substrate can also be used when a cholesteric liquid crystal layer whose pitch length continuously changes in the thickness direction is produced. A similar method can be adopted as the orientation method.

  In order for the phenomenon of the reflective polarizer of the present invention to function effectively, the cholesteric liquid crystal layer is preferably sufficiently thick. In general, in the case of a cholesteric liquid crystal layer having a single pitch length, sufficient selective reflection can be obtained if the thickness is about several pitches (2 to 3 times the selective reflection center wavelength). If the selective reflection center wavelength is in the range of 400 to 600 nm, considering the refractive index of the cholesteric liquid crystal, it functions as a polarizing element if the thickness is about 1 to 1.5 μm. Since the cholesteric liquid crystal layer used for the reflective polarizer has a reflection band in a wide band, the thickness is preferably 2 μm or more. The thickness is desirably 4 μm or more, more desirably 6 μm or more.

  The reflective polarizer (polarizing element) formed by the cholesteric liquid crystal layer can be used together with the alignment base material or by peeling from the alignment base material.

  The polarizing filter of the present invention can use a polarizing element having the above function, and the polarizing element can be used by being laminated on a translucent support substrate. FIG. 12 is a cross-sectional view of a polarizing filter F in which a light transmitting support base material S is laminated on a polarizing element A.

  Examples of the translucent support base include glass and translucent resin. Examples of the translucent resin include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymers, and the like. Examples thereof include styrene polymers such as (AS resin) and polycarbonate polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples include polymer blends.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing a thermoplastic resin having unsubstituted phenyl and a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference, a small photoelastic coefficient, and a low moisture permeability, they have excellent humidification durability.

  The thickness of the translucent support base material is not particularly limited, but is preferably about 0.05 to 10 mm. Lamination of the polarizing element to the translucent support substrate can be performed by bonding with a pressure-sensitive adhesive, an adhesive, or the like.

  In addition, a polarizing filter hard coat layer, a stain-proof layer and a water repellent treatment layer can be provided. Usually, it is provided on the surface of the polarizing filter. These layers can be provided with a plurality of types of layers.

  The polarizing filter of the present invention can be used as polarizing sunglasses. As the polarizing sunglasses, it is preferable to use a polarizing filter F in which a translucent support base material S is laminated on the polarizing element A. Examples of the translucent support base include the same materials as described above, such as glass and translucent resin.

  As the polarized sunglasses, those having a light-absorbing semi-transmissive layer are suitable as described above. FIG. 13 shows a case where the light-transmitting translucent layer E is provided on the polarizing element A side of the polarizing filter F in which the light-transmitting supporting substrate S is laminated on the polarizing element A. As the light-absorbing translucent layer E, a colored translucent support substrate can be used. For coloring, the inside of the substrate may be dyed, or only the surface may be dyed, or a colored layer may be formed on the surface. The degree of coloring of the light-absorbing semi-transmissive layer E is preferably, for example, a transmittance of 10 to 70%. The transmittance is a value measured by a spectrophotometer U4100 manufactured by Hitachi, Ltd.

  Moreover, as shown in FIG. 14, what laminated | stacked the polarizing element A on the light-absorbing semi-transmissive layer E can be used. In this case, as the light-absorbing semi-transmissive layer E, a colored translucent support base material conventionally used for sunglasses or the like can be applied as it is. When used in the embodiment of FIG. 14, the thickness of the light-absorbing semi-transmissive layer E is preferably about 0.05 to 10 μm, which is a typical thickness of sunglasses.

  Further, as shown in FIG. 15, an absorptive polarizer PL can be used as the light-absorbing semi-transmissive layer E. When a linear polarizer is used as the absorptive polarizer PL, the characteristics in the axial direction of the linear polarizer can be added to the incident angle-dependent polarization characteristics of the polarizing element (reflection polarizer) A. If a circular polarizer is used as the absorbing polarizer PL, it hardly affects the transmittance in the vicinity of the front surface, and functions effectively only for cutting incident light from the side and obliquely behind.

  In any of the absorption type polarizers, since the front transmittance of the polarizing element (reflection polarizer) A alone is about 50%, it is generally preferable to use an absorption type polarizer having a high single transmittance. Is preferred. The desirable single transmittance of the absorbing polarizer is 40% or more, desirably 42% or more, and more desirably 44% or more.

  In the polarizing filter and the polarizing sunglasses of the present invention, since the polarized light needs to be maintained on the incident surface side, the supporting bases disposed between the polarizing element (reflective polarizer) A and the reflector are polarized. It is desirable to use a material that does not disturb. On the other hand, since disorder of polarization including depolarization does not become a problem between the polarizing element (reflection polarizer) A and the eye, as a support substrate having a phase difference as a translucent support substrate, for example, polyethylene A terephthalate film or the like can be used.

  Examples of linear polarizers include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films, and two types of iodine and dichroic dyes. Examples thereof include a polyene-based oriented film such as a film obtained by adsorbing a chromatic substance and uniaxially stretched, a dehydrated polyvinyl alcohol product or a dehydrochlorinated polyvinyl chloride product. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride and the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed with dyeing after iodine. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  Moreover, what has a protective film on both surfaces of a polarizer can be used for the said linear polarizer. The protective film provided on the polarizer preferably has excellent transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic properties, and the like. Examples of the protective film are the same as those of the translucent support substrate.

  The surface of the protective film to which the polarizer is not adhered may be subjected to a treatment for the purpose of hard coat layer, antireflection treatment, antisticking, diffusion or antiglare.

  Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipping properties with an appropriate ultraviolet curable resin such as acrylic or silicone is applied to the protective film. It can be formed by a method of adding to the surface. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the protective film itself, or can be provided separately from the protective film as an optical layer.

  The circular polarizer can be obtained, for example, by combining a ¼ wavelength plate with the linear polarizer. As a quarter wave plate, a birefringent film or a liquid crystal polymer obtained by stretching a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefin, polyarylate, or polyamide. And a film in which an alignment layer of a liquid crystal polymer is supported by a film.

  For the lamination of the polarizing filter and the polarizing sunglasses, an adhesive material and an adhesive material can be used. The adhesive material and the adhesive material are not particularly limited, but for example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. Further, an ultraviolet curable type can be used.

  Hereinafter, the present invention will be specifically described with reference to examples. The reflection bandwidth is measured by measuring the reflection spectrum of the cholesteric liquid crystal layer (polarizing element) with a spectrophotometer (Otsuka Electronics Co., Ltd., instantaneous multi-photometry system MCPD-2000). It was set as the reflection band which has. Further, UVC321AM1 manufactured by USHIO INC. Was used as the ultraviolet exposure machine used in each example.

  (Distortion rate): In order to evaluate the distortion rate of the polarizing element, the transmission spectrum of the sample was measured with an instantaneous multiphotometer (MCPD-2000 manufactured by Otsuka Electronics Co., Ltd.). When natural light is projected and the sample is installed perpendicularly to the projected light (measurement of outgoing light from the front), and when the sample is installed at an angle of 60 ° from the vertical direction (measurement of 60 ° outgoing light) About each, the state of the light which permeate | transmitted them was measured with the polarizing plate arrange | positioned at the output side, and the transmission spectrum when a polarizing plate was rotated 10 degrees at a time was measured. As the polarizing plate, a Sigma-Optical Gram Thompson prism polarizer was used (extinction ratio of 0.00001 or less). The distortion rate was obtained from the following calculation formula. Strain rate = minimum transmittance / maximum transmittance.

Production Example 1
A monofunctional mesogen compound (Takasago International Corporation, L42) 95.1 parts by weight, a bifunctional chiral agent (BASF LC756) 4.9 parts by weight, and a solvent (cyclopentanone) 233 parts by weight were blended. A coating liquid (solid content 30 wt%) was prepared by adding 5 wt% of a photopolymerization initiator (Ciba Specialty Chemicals, Irgacure 369) to the solution. The coating solution was applied onto a stretched polyethylene terephthalate film (alignment substrate) using a wire bar so that the thickness after drying was 10 μm, and the solvent was dried at 100 ° C. for 2 minutes. As a step (1), the obtained film was irradiated with ultraviolet rays at 139 mW / cm ² for 0.1 seconds in an air atmosphere at 100 ° C. from the alignment substrate side. Next, as step (2), heat treatment was performed for 120 seconds in an air atmosphere at 100 ° C. Further, step (1) and step (2) were repeated. Thereafter, as step (3), ultraviolet irradiation from the liquid crystal layer side was performed at 60 mW / cm ² for 30 seconds in a nitrogen atmosphere at 50 ° C. to obtain a cholesteric liquid crystal layer (polarizing element) having a selective reflection band of 430 to 1010 nm. .

  The cholesteric liquid crystal layer thus obtained transmitted circularly polarized light in the normal direction, but linearly polarized approximate light was obtained at an incident angle of about 30 °. The distortion rate was 0.95 in the normal direction, the distortion rate was 0.39 in the direction of the incident angle of 30 °, and 0.04 in the direction of the incident angle of 60 °. The polarization axis of the obliquely reflected light of the obtained cholesteric liquid crystal layer substantially coincided with the axial direction of the surface reflection component such as the water surface, and functioned as a reflective polarizer capable of removing the surface reflected light.

Production Example 2
Five kinds of cholesteric liquid crystal polymers having selective reflection center wavelengths of 430 nm, 480 nm, 550 nm, 630 nm, and 720 nm were prepared based on European Patent Application No. 0837544.

  The cholesteric liquid crystal polymer has the following chemical formula 2:

で表される重合性ネマチック液晶モノマーＡと、下記化３：

A polymerizable nematic liquid crystal monomer A represented by the formula:

で表される重合性カイラル剤Ｂを、下記に示す割合（重量比）
選択反射中心波長（ｎｍ） モノマーＡ／カイラル剤Ｂ（配合比）
４３０ｎｍ ８．５／１
４８０ｎｍ ９．８１／１
５５０ｎｍ １１．８／１
６３０ｎｍ １４．２／１
７２０ｎｍ １６．６／１
で配合した液晶混合物を重合することにより作製した。

The polymerizable chiral agent B represented by the following ratio (weight ratio)
Selective reflection center wavelength (nm) Monomer A / Chiral agent B (blending ratio)
430nm 8.5 / 1
480 nm 9.81 / 1
550 nm 11.8 / 1
630 nm 14.2 / 1
720 nm 16.6 / 1
It was produced by polymerizing the liquid crystal mixture blended in 1.

  Each liquid crystal mixture was made into a 33 wt% solution dissolved in tetrahydrofuran, and then purged with nitrogen in an environment of 60 ° C. to obtain a reaction initiator (azobisisobutyronitrile, 0.5 wt% based on the mixture). ) Was added for polymerization treatment. The resulting polymer was purified by reprecipitation separation with diethyl ether.

  The cholesteric liquid crystal polymer was dissolved in methylene chloride to prepare a 10% by weight solution. The solution was applied to the alignment substrate with a wire bar so that the thickness upon drying was about 2 μm. A 75 μm-thick polyethylene terephthalate (PET) film was used as the alignment substrate, and a surface of which a polyvinyl alcohol layer was applied to a thickness of about 0.1 μm and rubbed with a rayon rubbing cloth was used. After coating, it was dried at 140 ° C. for 15 minutes. After this heat treatment, the liquid crystal was cooled and fixed at room temperature to obtain a thin film.

  The cholesteric liquid crystal layer and triacetyl cellulose (TAC) were bonded together with an acrylic pressure-sensitive adhesive and dried at 80 ° C. for 5 minutes. Subsequently, only PET was gently peeled off. In this operation, a polarizing element having a thickness of 10 μm was obtained by sequentially stacking five layers so that the cholesteric liquid crystal layer was changed from the long wavelength side to the short wavelength side. The obtained polarizing element had a selective reflection band at 430 nm to 720 nm.

  The cholesteric liquid crystal layer thus obtained transmitted circularly polarized light in the normal direction, but linearly polarized approximate light was obtained at an incident angle of about 30 °. The distortion rate was 0.88 in the normal direction, the distortion rate was 0.55 in the direction of the incident angle of 30 °, and 0.16 in the direction of the incident angle of 60 °. The polarization axis of the obliquely reflected light of the obtained cholesteric liquid crystal layer substantially coincided with the axial direction of the surface reflection component such as the water surface, and functioned as a reflective polarizer capable of removing the surface reflected light.

Production Example 3
Five kinds of cholesteric liquid crystal polymers having selective reflection center wavelengths of 420 nm, 480 nm, 550 nm, 620 nm, and 690 nm were prepared.

The cholesteric liquid crystal polymer is a ratio (weight ratio) of a liquid crystal monomer A which is a polymerizable mesogen compound (LC242 manufactured by BASF) and a polymerizable chiral agent B (LC756 manufactured by BASF) shown below.
Selective reflection center wavelength (nm) Monomer A / Chiral agent B (blending ratio)
420nm 94/6
480nm 95/5
550 nm 95.5 / 4.5
620 nm 96.5 / 3.5
720nm 97/3
It was produced by polymerizing the liquid crystal mixture blended in 1.

  The liquid crystal mixture is made into a 20 wt% solution in which each is dissolved with cyclopentane, and then a photoreaction initiator (Ciba Specialty Chemicals, Irgacure 907, 1 wt% with respect to the mixture) is added to form a solution. Prepared.

  The solution was applied to the alignment substrate with a wire bar so that the thickness upon drying was about 2 μm. As the alignment base material, a polyethylene terephthalate film manufactured by Toray Industries, Inc .: a film obtained by aligning Lumirror 75 μm with a rubbing cloth was used. After coating, the film is dried at 90 ° C. for 2 minutes, heated once to the isotropic transition temperature (130 °), and then gradually cooled and irradiated with ultraviolet rays in an environment of 80 ° C. while maintaining a uniform orientation state (10 mW / The cholesteric liquid crystal layer was obtained by curing at a square cm × 1 minute. The obtained film of each wavelength was bonded by ultraviolet irradiation (10 mW / square cm × 1 minute) using a translucent adhesive (NORLAND, NOA68, thickness: 2 μm). The obtained polarizing element had a selective reflection band of about 400 to 750 nm.

  The cholesteric liquid crystal layer thus obtained transmitted circularly polarized light in the normal direction, but linearly polarized approximate light was obtained at an incident angle of about 30 °. The distortion rate was 0.90 in the normal direction, the distortion rate was 0.42 in the direction of the incident angle of 30 °, and 0.08 in the direction of the incident angle of 60 °. The polarization axis of the obliquely reflected light of the obtained cholesteric liquid crystal layer substantially coincided with the axial direction of the surface reflection component such as the water surface, and functioned as a reflective polarizer capable of removing the surface reflected light.

  The following evaluation was performed about the obtained polarizing element.

Example 1
Polarized sunglasses as shown in FIG. 13 were produced. As the support substrate, an acrylic support substrate: Sumibex-Clear product (2 mm thickness) manufactured by Sumitomo Chemical Co., Ltd. was used. As the polarizing element, the reflective polarizer obtained in Production Example 1 was used. As the light-absorbing semi-transmissive layer, a colored barrier PET film manufactured by Sumitomo Osaka Cement Co., Ltd. (with a transmittance of 79%) was used. The order of lamination is the order of “support base material—UV adhesive material—reflecting polarizer—adhesive material—light-absorbing semi-transmissive layer” from the incident surface side. The support base material and the reflective polarizer were laminated with an ultraviolet curable adhesive, and the ray barrier film was laminated using the laminated adhesive material as it was. As the adhesive, an ultraviolet curable adhesive (NORLAND, NOA68) was used.

Example 2
Polarized sunglasses as shown in FIG. 14 were produced. As the polarizing element, the reflective polarizer obtained in Production Example 2 was used. As the light-absorbing semi-transmissive layer, sunglasses made of dyed resin: a commercial product (made of polycarbonate resin CR39 for spectacles) was used. The stacking order is “reflection polarizer-adhesive material—light-absorbing semi-transmissive layer” from the incident surface side. The adhesive material is Nitto Denko NO. 7 Acrylic adhesive (25 μm thick) was used.

Example 3
Polarized sunglasses as shown in FIG. 15 were produced. As the polarizing element, the reflective polarizer obtained in Production Example 3 was used. As the light-absorbing semi-transmissive layer, a linear polarizer: EGW5226DU-HC-ARC manufactured by Nitto Denko Corporation was used. The stacking order is “reflection polarizer-adhesive material—light-absorbing semi-transmissive layer” from the incident surface side. The adhesive material is Nitto Denko NO. 7 Acrylic adhesive (25 μm thick) was used.

Example 4
Polarized sunglasses as shown in FIG. 15 were produced. As the polarizing element, the reflective polarizer obtained in Production Example 1 was used. As the light-absorbing semi-transmissive layer, a laminated product of circular polarizer: EGW5226DU-HC-ARC (linear polarizer) manufactured by Nitto Denko Corporation and NRF 140 nm (¼ wavelength plate) manufactured by Nitto Denko Corporation was used. The stacking order is “reflection polarizer-adhesive material—light-absorbing semi-transmissive layer” from the incident surface side. The quarter wave plate was placed between the reflective polarizer and the linear polarizer. The lamination of the linear polarizer and the quarter wavelength plate was arranged so that the axial angle was 45 degrees. The adhesive material is Nitto Denko NO. 7 Acrylic adhesive (25 μm thick) was used.

  The polarized sunglasses obtained in Examples 1 to 4 were put on and the object under the water surface was confirmed. Visibility improved when wearing polarized sunglasses. On the other hand, the visibility of the liquid crystal monitor did not change when wearing polarized sunglasses. Even when the neck angle was changed intentionally by tilting the neck, the front direction functioned as a circularly polarizing plate, and since there was no azimuth, no change in transmittance was observed. Furthermore, the showcase using the vertically arranged glass plate was visually confirmed from an oblique side. Visibility was easily improved by shifting the line of sight in an oblique direction when visually recognizing. Moreover, the incident light from the oblique back was absorbed by the light-absorbing semi-transmissive layer and was not dazzled.

Comparative Example 1
Evaluation similar to the example was performed with commercially available polarized sunglasses (CR-39 plastic and glass material were used, and a dye-based polarizing element was sandwiched and integrally molded so as not to cause distortion of the lens). . The visibility of underwater objects has been improved. However, when the liquid crystal monitor is viewed, there is a case where the brightness is significantly lowered. When the head was shaken, the brightness changed remarkably, which was uncomfortable. Further, when looking into the glass showcase from the side, there was no improvement in visibility.

It is a conceptual diagram which shows the polarization axis direction of the emitted light which permeate | transmitted the polarizing element (reflective polarizer) of this invention. It is a conceptual diagram which shows the polarization-axis direction of the emitted light at the time of seeing FIG. 1 (A) from the normal line direction of a polarizing element (reflection polarizer). It is a conceptual diagram which shows the polarization axis direction of the emitted light which permeate | transmitted the polarizing element (reflective polarizer) of this invention. It is a conceptual diagram which shows the polarization-axis direction of the emitted light at the time of seeing FIG. 2 (A) from the normal line direction of a polarizing element (reflection polarizer). It is a conceptual diagram explaining a polarization component. It is a conceptual diagram which shows the polarization separation by the conventional cholesteric liquid crystal layer. It is a conceptual diagram which shows the polarization separation by the conventional cholesteric liquid crystal layer. It is a conceptual diagram which shows the polarization separation by the polarizing element (cholesteric liquid crystal layer) of this invention. It is a conceptual diagram which shows the polarization separation by the polarizing element (cholesteric liquid crystal layer) of this invention. It is a conceptual diagram which observes a water surface with the polarizing filter (polarized sunglasses) of this invention. It is a conceptual diagram which observes a show window with the polarizing filter (polarized sunglasses) of this invention. It is a conceptual diagram which observes a show window with the polarizing filter (polarized sunglasses) of this invention. It is a conceptual diagram which observes a liquid crystal panel and a water surface with the polarizing filter (polarization sunglasses) of this invention. In the polarized sunglasses of the present invention, it is a conceptual diagram showing the influence of reflection of incident light from around the eyes. In the polarized sunglasses of the present invention, it is a conceptual diagram for suppressing the influence of reflection of incident light from around the eyes. It is an example of sectional drawing of the polarizing filter (polarization sunglasses) of the present invention. It is an example of sectional drawing of the polarized sunglasses of the present invention. It is an example of sectional drawing of the polarized sunglasses of the present invention. It is an example of sectional drawing of the polarized sunglasses of the present invention.

Explanation of symbols

A Polarizing element (reflective polarizer)
i incident light e outgoing light r1 reflected light from a reflector (linearly polarized light)
r2 Linearly polarized light orthogonal to r2 r3 Circularly polarized light E Absorbing semi-transmissive layer F Polarizing filter S Translucent support base material PL Absorbing polarizer

Claims (13)

  A polarizing filter having a function of transmitting circularly polarized light with respect to incident light in a normal direction and a function of reflecting linearly polarized light with respect to incident light in an oblique direction.   A polarizing element having at least a function of transmitting circularly polarized light with respect to incident light in a normal direction and having a function of reflecting linearly polarized light with respect to incident light in an oblique direction is used. The polarizing filter according to 1.   A polarizing element having a function of transmitting circularly polarized light with respect to incident light in the normal direction and reflecting linearly polarized light with respect to incident light in an oblique direction with an incident angle of 30 ° or more with respect to the normal direction. The polarizing filter according to claim 1, wherein the polarizing filter is used at least.   4. The polarizing filter according to claim 2, wherein the polarizing element is a reflective polarizer formed by a cholesteric liquid crystal layer having polarization separation characteristics, which emits incident light after polarization separation. In the reflective polarizer, the outgoing light with respect to the incident light in the normal direction has a distortion rate of 0.5 or more,
The outgoing light with respect to the incident light that is inclined by 60 ° or more from the normal direction has a distortion rate of 0.2 or less,
5. The polarizing filter according to claim 4, wherein the linearly polarized light component of the emitted light increases as the incident angle increases.   The reflective polarizer is characterized in that the linearly polarized light component of the emitted light that increases as the incident angle increases has a polarization axis of linearly polarized light in a direction substantially orthogonal to the normal direction of the polarizing element surface. 5 polarizing filter.   The reflective polarizer has a linearly polarized light polarization axis substantially parallel to the normal direction of the polarizing element surface, wherein the linearly polarized light component of the outgoing light increases as the incident angle increases. 5 polarizing filter.   The polarizing filter according to claim 4, wherein the reflective polarizer has a reflection bandwidth of 200 nm or more.   2. The polarizing filter is provided such that the reflection axis direction of linearly polarized light with respect to obliquely incident light in the polarizing filter is a direction that reflects reflected light obliquely from the water surface and blocks transmission. The polarizing filter in any one of -8.   The polarizing filter according to claim 1, comprising at least one layer selected from a hard coat layer, a stain-proofing layer, and a water-repellent treatment layer.   Polarized sunglasses using the polarizing filter according to claim 1.   The polarizing sunglasses according to claim 11, wherein a light-absorbing semi-transmissive layer is provided closer to the eye than the polarizing filter.   13. The polarized sunglasses according to claim 12, wherein the light-absorbing semi-transmissive layer is an absorptive polarizer.

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