WO2019216120A1

WO2019216120A1 - Polarization plate and display device using polarization plate

Info

Publication number: WO2019216120A1
Application number: PCT/JP2019/016003
Authority: WO
Inventors: 長谷川　亮; 大輔谷岡
Original assignee: 株式会社ポラテクノ
Priority date: 2018-05-09
Filing date: 2019-04-12
Publication date: 2019-11-14
Also published as: CN112534315A; TWI802687B; KR20210006970A; TW201946775A; CN112534315B; JPWO2019216120A1

Abstract

This polarization plate has: a hard coat layer on one surface; and an adhesive layer on the other surface. A polarizer of the polarization plate includes at least one dichroic dye. The polarization plate has a single-film transmittance Ys of 45-60% and a polarization degree Py of 50-95%, which are obtained through measurement of light in a wavelength range of 380-780 nm and then visibility correction thereof. The polarization plate has a*s of not less than -3 but not more than +3 and b*s of not less than -3 but not more than +3 in the hue of an L*a*b* color system, and has a*p of not less than -3 but not more than +3 and b*p of not less than -3 but not more than +3 in the hue when two polarizing films are used so that the polarization axes thereof are positioned in parallel.

Description

Polarizing plate and display device using the same

The present disclosure relates to a polarizing plate and a display device using the polarizing plate.

In recent years, a mirror display in which a mirror (mirror) and a display (image display device) are combined and integrated has been widely used. In particular, when the rear-view mirror of an automobile is used as a mirror display, the rear view can be projected with a camera provided outside the rear of the automobile to compensate for the blind spot obstructed by the rear seat or the pillar of the vehicle. , Safer driving becomes possible.

The mirror display is typically known as the half mirror system, and has a display device under the half mirror to display images so as to emerge from the mirror, or to switch between the mirror state and the image display state. It is a display device that can.

On the other hand, a mirror display having a shutter mechanism for switching between a display mode and a mirror mode on the front surface of the display device has been proposed (hereinafter referred to as a liquid crystal shutter method). In this method, a liquid crystal cell including an absorption-type polarizing plate and a reflective-type polarizing plate is provided on the front surface of the display device unit, and an image display mode and a mirror mode can be switched by driving the liquid crystal cell. Thus, the liquid crystal shutter method is particularly preferable as a rear mirror for automobiles because double reflection (a phenomenon in which an image display image and a reflected image can be seen simultaneously), which has been a problem in the half mirror method, is reduced.

As the absorptive polarizing plate used on the viewing side of such a mirror display, a polarizing plate provided with a polarizer formed by dyeing and stretching a dichroic dye such as iodine or a dye on polyvinyl alcohol is used. At this time, it is good also as a polarizing plate which has high transmittance | permeability and high polarization degree from the image display property of a mirror display, and the reflective characteristic at the time of mirror display. Therefore, an iodine polarizing plate having optical properties superior to that of a dye polarizing plate is used, and the single transmittance of the polarizing plate when the polarizing property and the display contrast are combined is 42 to 45% and the degree of polarization is 96.6 to 99. .5%. Thereby, the linearly polarized light from the image display unit can be emitted with high transmission.

Challenges to be solved

The iodine polarizing plate having a high degree of polarization generally has a low transmittance characteristic on the short wavelength side (near 420 nm). Therefore, when the polarizing plate is used as a polarizing member for a shutter of the mirror display, a display mode or a mirror mode is used. There is a problem that the display image is yellowish in color, and the appearance is worse than a conventional mirror made of a glass plate and metallic luster. The waveform balance and hue of the polarizing plate are generally adjusted by adjusting the blending conditions of the dichroic dye, the dyeing conditions of the polarizing film, etc. However, in the polarizing plate using only the iodine-based dye, the polarizing plate has a neutral hue. It is not easy to adjust to.

Also, in order to improve the function as a mirror, the reflectance in the mirror mode can be improved by increasing the transmittance of the polarizing plate. In this case, in the iodine-type polarizing plate, the transmittance can be increased by reducing the dyeing amount of iodine in the polarizing film. However, a polarizing plate including a polarizing film having a high transmittance by reducing the amount of iodine significantly reduces optical durability against high temperatures and high temperatures and high humidity. Therefore, it is not suitable as a member requiring high durability such as an automobile.

From the above, the use of an iodine-based polarizing plate as the absorption-type polarizing plate in the liquid crystal shutter portion cannot satisfy the above requirements, and therefore a polarizing plate having characteristics suitable for the method is required. Further, since the mirror member is configured by laminating films such as polarizing plates, the display image fluctuates if the film has poor smoothness or has distortion (swells). Therefore, in the mirror display of the said system, it is necessary to maintain the display quality comparable with the mirror using the conventional smooth glass surface.

An object of the present disclosure is to provide a polarizing member that is an absorptive polarizing plate of the shutter portion in a liquid crystal shutter-type mirror display and has excellent optical characteristics, durability, and display quality. That is, one aspect of the present disclosure includes a polarizing plate having a hard coat layer on one surface and an adhesive layer on the other surface, and the polarizer of the polarizing plate contains at least one dichroic dye, The plate has a single transmittance Ys corrected in terms of visibility measured for light in a wavelength region of 380 nm or more and 780 nm or less, 45% or more and 60% or less, and the degree of polarization Py is 50% or more and 95% or less. Is a hue of a single L * a * b * color system, a * s is −3 to +3 and b * s is −3 to +3, and the polarizing axis is composed of two polarizing plates. The polarizing member is characterized in that a * p is −3 to +3 and b * p is −3 to +3 in terms of hue when in parallel.

Here, the pressure-sensitive adhesive layer may have a swell degree of 7 or less, and the polarizing member may have a swell degree of 15 or less.

Further, the dichroic dye may include a water-soluble disazo compound represented by the chemical formula (1) or a copper complex salt compound thereof.

(Wherein X represents a hydrogen atom, a methyl group, a methoxy group or an ethoxy group, Y represents a methoxy group or an ethoxy group, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom, a methyl group,- C ₂ H ₄ OH group, a substituted or unsubstituted phenyl group, a phenyl group substituted with a carboxy group, and a phenyl group substituted with a sulfone group.)

The polarizing member may be used for a liquid crystal shutter type mirror display.

Another aspect of the present disclosure is a liquid crystal shutter type mirror display in which the polarizing member, a shutter liquid crystal cell, a reflective polarizing plate, and an image display device are arranged in this order from the viewing side. It is.

effect

According to the present disclosure, it is possible to provide a polarizing member that suppresses coloring of a display image and a reflected image and is highly durable and maintains display stability while maintaining an emission luminance equivalent to that of an iodine polarizing plate having a high degree of polarization. Can do. As a result, a liquid crystal shutter-type mirror display that displays high-quality images and reflected images can be realized.

It is a cross-sectional schematic diagram which shows the structure of the polarizing member in embodiment of this indication. It is a figure which shows the measurement result of the linearly polarized light transmittance with respect to the wavelength in Example 1 and Comparative Example 1.

Form to carry out

The polarizing member 100 in the embodiment of the present disclosure includes an adhesive layer 10, a first support film 12 a, a polarizing film 14, a second support film 12 b, and a hard coat layer 16 as shown in the schematic cross-sectional view of FIG. 1. Composed. FIG. 1 is a schematic diagram to the last, and the actual film thickness and the like of each layer are not as illustrated.

The polarizing member 100 can be a member of a liquid crystal shutter type mirror display, and is provided, for example, on the viewing side of a mirror display mounted on an automobile rearview mirror or the like. The mirror display may include a display device on the entire surface, and the mirror and the display image may be switched on the entire surface or a part thereof, or may include at least one display device on a part of the entire surface, and the part may be a mirror partly. The display image may be switched. The display image is information displayed on the display unit, and indicates color display such as an image or a moving image or simple display using dots or segments such as alphanumeric characters.

A liquid crystal shutter type mirror display is provided with an absorption type polarizing plate, a liquid crystal cell, and a reflection type polarizing plate in this order from the viewing side as a shutter member on the front surface of a liquid crystal display device or the like, and can switch between a mirror state and an image display state. It is a display device that can.

The light emitted from the display device is linearly polarized light. In the display mode of the display (the image is monitored on the display device), the transmission axes of the polarizing plate, the reflective polarizing plate, and the absorbing polarizing plate on the front surface of the display device are in a parallel relationship. That is, this method can suppress a decrease in the amount of light from the display device as compared to the half mirror method. At this time, since the absorption axis of the absorptive polarizing plate is orthogonal to the transmission axis of the reflective polarizing plate, the reflected light (reflected polarized light) of the reflective polarizing plate is absorbed by the absorptive polarizing plate. Thereby, double reflection in the display mode is reduced.

In the mirror mode, the transmission axes of the reflective polarizing plate and the absorbing polarizing plate are orthogonal to each other. In this case, external light (natural light) reflection is transmitted from the absorptive polarizing plate (becomes linearly polarized light), then reflected by the reflective polarizing plate, and again transmitted through the absorptive polarizing plate. Therefore, in order to obtain a higher reflectance, it is preferable that the absorption-type polarizing plate has a higher transmittance, and thus a highly visible mirror is obtained.

In the liquid phase cell, the liquid crystal layer is sandwiched between transparent electrodes. Specifically, when the incident linearly polarized light is transmitted, the polarization axis is changed and the polarization axis is not changed. This element has a structure that can be selected by electrical switching. Thereby, the relationship of the polarization axis of an absorption type polarizing plate and a reflection type polarizing plate switches, and the state of a mirror and the state of an image display can be switched. As the liquid crystal cell, TN (twisted nematic) type liquid crystal is typically used.

The reflective polarizing plate includes a polarizer having a function of transmitting polarized light parallel to the transmission axis and reflecting polarized light orthogonal to the transmission axis, and serves as a mirror in the mirror display according to the present embodiment. As the polarizing plate, for example, a birefringent reflective polarizing film in which a plurality of different birefringent polymer films are alternately laminated can be used. Examples of commercially available reflective polarizing films include DBEF series manufactured by 3M. It is done. Examples of other reflective polarizing films include films having a structure in which quarter-wave retardation layers are disposed on the front and back of a cholesteric liquid crystal layer. Furthermore, a wire grit type inorganic polarizing plate can be used as a reflective polarizing plate. These films are used by being bonded to a liquid crystal cell via an adhesive layer or an adhesive layer. In addition, in order to reduce internal reflection between the display device unit and the liquid crystal shutter unit, that is, between the reflective polarizing plate, for example, an optical adhesive layer may be provided and laminated, or antireflection on both surfaces. A layer may be provided.

The polarizing plate (absorption type polarizing plate) according to the present disclosure will be described below.

[Polarizer]
The polarizing plate has a configuration in which a supporting film 12 (in FIG. 1, a first supporting film 12a and a second supporting film 12b are bonded to both sides) on one side or both sides of a polarizing film 14 having a polarizer. Although only the polarizing film 14 can be used, it is preferable to use it as a polarizing plate in which both surfaces of the polarizing film 14 are sandwiched between the first support film 12a and the second support film 12b. This is because the polarizing film 14 is generally a uniaxially stretched polyvinyl alcohol resin (PVA) film dyed with a dichroic dye, and is a thin film, so that the first support film 12a and the first film This is because, in a state where the film is not sandwiched between the two support films 12b, the film is easily deformed by heat or moisture, and the polarization characteristics may be impaired.

The polarizing film 14 is a film having a function of converting natural light into linearly polarized light, and may be obtained by adsorbing and orienting a dichroic dye on a PVA film. Examples of dichroic dyes include azo compounds, anthraquinone compounds, and tetrazines. Especially when dichroic dyes of azo compounds are used, optical properties under high temperature conditions and high temperature and high humidity conditions are used. Excellent durability of properties and easy hue adjustment. Therefore, when the dichroic dye is used, even if the polarizing film 14 is arranged on the display device, the influence of yellowish coloring can be suppressed as compared with the iodine polarizing film.

The dichroic dye used for the polarizing film 14 is preferably an azo compound dye from the viewpoint of optical properties and durability. I. Direct Yellow 12, C.I. I. Direct Yellow 28, C.I. I. Direct Yellow 44, C.I. I. Direct Orange 26, C.I. I. Direct Orange 39, C.I. I. Direct Orange 107, C.I. I. Direct Red 2, C.I. I. Direct Red 31, C.I. I. Examples include Direct Red 79, dyes described in JP-A No. 2003-215338, and dyes described in WO 2007/138980.

Examples of commercially available dyes include Kayafect Violet P Liquid (manufactured by Nippon Kayaku Co., Ltd.), Kayafect Yellow Y, Kayafect Orange G, Kayafect Blue KW, and Kayafect Blue Liquid 400.

Furthermore, a dichroic dye optimized for obtaining the hue of the achromatic polarizing plate described in WO2015 / 186661, WO2014 / 162634 may be used.

At this time, it is preferable that a hue of neutral gray is obtained by blending two or more of these dyes so as to supplement the polarization characteristics at each wavelength in the visible range and dyeing them on PVA. For example, in the case of blending three or more kinds of dyes including a blue dichroic dye, the polarizing film 14 is arranged on the display device by adjusting the blending amount of the blue dichroic dye. It is possible to optimize the degree of coloring of the yellowish color at the time or to match the coloring of blue. Moreover, the neutral gray color can be adjusted more easily by using a dichroic dye optimized to obtain an achromatic hue. Examples of the commercially available dye-based polarizing plate include “achromatic” series manufactured by Polatechno Co., Ltd.

It is particularly preferable from the viewpoint of durability that the azo compound contains a water-soluble disazo compound represented by the chemical formula (2) or the copper complex salt compound.

Here, X represents a hydrogen atom, a methyl group, a methoxy group or an ethoxy group, and Y represents a methoxy group or an ethoxy group. R ₁ represents a hydrogen atom or a methyl group, and R ₂ is substituted with a hydrogen atom, a methyl group, a —C ₂ H ₄ OH group, a substituted or unsubstituted phenyl group, a phenyl group substituted with a carboxy group, or a sulfone group. Represents a phenyl group.

As the compound, a commercially available compound may be used, and it can be produced by a known production method, for example, a production method described in JP-A-59-145255.

Furthermore, it is preferable that the water-soluble compound represented by the chemical formula (3) or a copper complex compound thereof is included as the azo compound.

Here, A represents a phenyl group or naphthyl group substituted with a methyl group, and R represents an amino group, a methylamino group, an ethylamino group, or a phenylamino group.

As the compound, a commercially available compound may be used, and it can be produced by a known production method, for example, a production method described in JP-A-3-12606.

When a dichroic dye is used as a dichroic dye, durability of optical properties under high temperature conditions and high temperature and high humidity conditions is superior to iodine, and color change during molding is less than that of iodine. Therefore, the hue of the polarizing film 14 can be easily adjusted, and the yellowness can be lowered as compared with the case where iodine is used as the dichroic dye.

The polarizing film 14 or the polarizing plate suitable for the polarizing member 100 has a single transmittance Ys corrected in terms of visibility measured with respect to light in a wavelength region of 380 nm to 780 nm and a polarization degree Py of 50% to 60%. % Or more and 95% or less is preferable. However, the relationship between the single transmittance Ys and the optical property of the degree of polarization Py is the case of a polarizing film using a general dichroic dye. There is a possibility that optical properties may be improved by improving the performance and orientation of individual dichroic dyes. In that case, Py may exceed the range above the range of Ys.

When the single transmittance Ys is less than 45%, the polarization degree Py exceeds 95%. In this case, the transmittance of linearly polarized light is about 85% or less. Therefore, it is not possible to obtain a display luminance equivalent to that of an iodine-based polarizing plate (single transmittance Ys: 43%, linearly polarized light transmittance: about 86%), and coloration of the display image cannot be improved. .

In the case of a polarizing plate having a single transmittance Ys exceeding 60%, the degree of polarization Py is less than 50%, and sufficient polarization characteristics cannot be obtained, so that the shutter function of the mirror display may not sufficiently function.

Therefore, the preferable optical characteristic of the polarizing film 14 is that the single transmittance Ys is 45% or more and 60% or less, particularly 50% or more and 55% or less. As a result, the linearly polarized light transmittance is 87% or higher, and a display luminance equivalent to or higher than that of the iodine-based polarizing plate can be obtained. In this case, coloring of the display image can be suppressed as compared with the iodine polarizing plate. Furthermore, since the polarizing plate has a higher transmittance, the reflectance of natural light is improved and the visibility of the mirror mode is improved.

In order to prevent the image display image and the reflection image from being colored yellowish or the like by arranging the polarizing plate in front of the display device, the polarizing plate has a neutral hue with no color. It is preferable. Specifically, in the hue of the L * a * b * color system, the values of a * and b * of the polarizing plate are both 0 or close to 0. From the viewpoint of the characteristics of various dyes, it is not easy to produce a polarizing plate having such a hue value. Therefore, when applied to a mirror display, it is preferable to set a hue value that makes it difficult to visually recognize coloring. In the case of the polarizing plate alone (s), the hue values are preferably such that a * s is −3 to +3 and b * s is −3 to +3. Thereby, coloring can be suppressed in the image display image from the information device. Further, in the case of hue values when two polarizing plates are used and the polarization axis is parallel (p), it is preferable that a * p is −3 to +3 and b * p is −3 to +3. Thereby, coloring in the reflected image of a mirror can be suppressed.

The transmittance (unit:%) and the degree of polarization (unit:%) in the present embodiment are values measured by JASCO Corporation V-7100 or Hitachi, Ltd. U-4100. Specifically, a polarizing plate is produced, and the transmittance when one polarizing plate is used is the transmittance when the single polarizing plate Ys and the two polarizing plates are stacked so that the absorption axis directions are the same. Let the transmittance be the parallel transmittance Yp, and let the transmittance when the two polarizing plates are stacked so that the absorption axes are orthogonal to each other be the orthogonal transmittance Yc. The respective transmittances are calculated from the formula (1) by obtaining the spectral transmittance τλ at predetermined wavelength intervals dλ (here, 5 nm) in the wavelength region of 380 to 780 nm. In Equation (1), Pλ represents the spectral distribution of the standard light (C light source), yλ represents the color matching function of the double field of view, and τλ represents the spectral transmittance.

Also, the degree of polarization Py is obtained from the parallel transmission Yp and the orthogonal transmission Yc according to Equation (2).

The transmittance of linearly polarized light is the transmittance obtained by making absolute polarized light incident on the polarizing plate and measuring it so that the vibration direction of the absolute polarized light is perpendicular to the absorption axis direction of the polarizing plate. This is expressed as parallel transmittance Ky. Here, the absolute parallel transmittance Ky can be obtained by substituting the single-unit transmittance Ys and the orthogonal transmittance Yc obtained above into Equation (3). Note that the absolute parallel transmittance Ky may be obtained only for a predetermined wavelength of each wavelength from 380 nm to 780 nm, for example, depending on the design of the display device and the waveform characteristics of the polarizing plate. You may represent with the average value of a range.

When using the support film 12 as a polarizing plate, the support film 12 is bonded to one side or both sides of the polarizing film 14 through an adhesive layer. As support films 12 (first support film 12a, second support film 12b), cycloolefin resin film, polyester resin film, acrylic resin film, polycarbonate resin film, polysulfone resin film, alicyclic polyimide film A resin film, an acetylcellulose-based resin film, or the like can be applied. From the viewpoint of easily adhering to a polarizing film and obtaining a polarizing plate, it is preferable to use an acetyl cellulose resin, more preferably triacetyl cellulose (TAC).

Note that the transmittance on the short wavelength side (near 420 nm) decreases depending on the type of UV absorber or the like added to the support film, and as a result, b * s as a polarizing plate affects the increase. The degree of this increase is proportional to the thickness of the support film. Therefore, the thickness of the support film is preferably 100 μm or less, more preferably 40 to 80 μm, and it is preferable to have a polarizing plate configuration in which the influence of coloring is suppressed.

When automobile drivers wear polarized sunglasses, the polarization axes of the polarizing film 18 of the polarizing member 100 and the polarized sunglasses coincide with each other, and the display image may not be visible or may not be used as a mirror. Therefore, the visibility problem can be solved by providing a retardation film on the viewing side of the polarizing member 100, that is, the viewing side of the polarizing plate. In this Embodiment, you may affix together on the visual recognition side of a polarizing plate through an adhesion | attachment or an adhesion layer, and may use it as the support film 12b of a polarizing plate. In this case, it is preferable to provide a hard coat layer on the surface on the viewing side of the retardation film.

A retardation film is a film-like optical member made of a birefringent material. The thickness of the retardation film may be 5 μm or more and 200 μm or less, and may be 10 μm or more and 150 μm or less. When the thickness of the retardation film is less than 5 μm, the handleability as an industrial material is lowered. In addition, when the film thickness exceeds 200 μm, distortion and waviness associated with film formation tend to appear, and the quality of the display image of the mirror display may be impaired.

The material of the retardation film is, for example, a film obtained by stretching a film mainly composed of a polycarbonate resin, a polyester resin, a cycloolefin resin, or a transparent film coated with an ultraviolet curable polymer liquid product. And oriented ones can be selected.

The retardation of the retardation film may be in the range of 100 nm to 30000 nm. Examples of the retardation film include a λ / 4 retardation film, a λ / 2 retardation film, and a high retardation film having super birefringence.

In the retardation film, it is preferable that the relationship between the angle formed by the slow axis and the absorption axis of the polarizing plate 100 is in an angle range of greater than 0 ° and less than 90 °. That is, it is preferable to exclude the case where the slow axis of the retardation film coincides with the absorption axis of the polarizing plate 100 (relation angle is 0 °) and the case where they are orthogonal (relation angle is 90 °). The retardation film and the polarizing plate 100 are preferably laminated so as to be 40 to 50 degrees, more preferably 45 degrees. In such a relationship, since the polarized light emitted or reflected from the mirror display is not completely absorbed by the absorption axis of the polarized sunglasses, the display information of the device can be visually recognized even when the polarized sunglasses are worn.

For the polarizing member 100 including the retardation film, it is preferable to select a material and a manufacturing method in the above-described retardation film, adhesive or adhesive layer, hard coat layer, and the like so that the degree of undulation defined below is 15 or less. In particular, when an adhesive layer is used in the lamination of the polarizing plate and the retardation film, it is preferable to use an adhesive layer that suppresses the occurrence of “swell” described later. Thereby, also in the polarizing member 100 provided with retardation film, the mirror display which has a high-definition mirror surface with few distortions can be obtained.

[Adhesive layer 10]
The adhesive layer 10 is provided as a layer used when the polarizing member 100 is bonded to another member. The adhesive layer 10 is provided on the surface of the first support film 12a opposite to the polarizing film 14. The pressure-sensitive adhesive layer 10 is formed, for example, by applying a pressure-sensitive adhesive obtained by diluting a solid component of an acrylic or polyester pressure-sensitive adhesive with a solvent such as toluene or methyl ethyl ketone (MEK) to a release film and drying it. The pressure-sensitive adhesive is not particularly limited as long as it is acrylic or polyester-based, and other pressure-sensitive adhesives may be used. Add adhesives such as curing agents and silane coupling agents in the adhesive to adjust the adhesion to the adherend, and to prevent the occurrence of peeling and foaming in durability. Can do. Here, the dilution rate of the solid component with the solvent may be 5 times or less. Thereby, it can be set as the adhesion layer which suppressed generation | occurrence | production of the "swell" mentioned later.

Next, the blended adhesive is applied to a release film, and the solvent is volatilized in the drying step. In the drying step, the solvent may be volatilized from the release film coated with the pressure-sensitive adhesive using a plurality of drying furnaces each set to a temperature range of 40 ° C to 100 ° C.

At this time, the coating amount is adjusted so that the thickness of the pressure-sensitive adhesive after drying is 1 μm or more and 30 μm or less, more preferably 5 μm or more and 25 μm or less. Thereafter, the adhesive side is bonded to the first support film 12a.

[Hard coat layer 16]
The hard coat layer 16 is a layer for protecting the surface of the polarizing member 100. The hard coat layer 16 is provided on the surface on the opposite side of the polarizing film 14 of the second support film 12b. The hard coat layer 16 can be obtained, for example, by applying an ultraviolet curable resin to the surface of the second support film 12b and curing it by irradiating with ultraviolet rays. Specifically, for example, a solvent is prepared by mixing one or more polyfunctional (meth) acrylates, a polymerization initiator, and a surface conditioner with methyl ethyl ketone, which is a solvent, to prepare a paint, and apply it to one side of a TAC film. The hard coat layer 16 can be formed by drying the solvent at 40 to 80 ° C. and curing it by irradiating with ultraviolet rays using a high pressure mercury lamp. The film thickness of the hard coat layer 16 may be not less than 1 μm and not more than 20 μm from the viewpoints of the hardness and warpage (curl) after curing. When the film thickness is 20 μm or more, high hardness can be obtained, but the film is warped violently, which makes it difficult to bond to the polarizing film, and cracks occur in the hard coat layer due to bending during processing. There is a fear, and it may cause peeling of the durability test. Therefore, the film thickness may be 2 μm or more and 10 μm or less, and a hard coat layer having both hardness and workability can be obtained. In order to improve hardness and reduce warpage, a solvent in which nano-level colloidal silica is dispersed (for example, organosilica sol manufactured by Nissan Chemical Industries, Ltd.) may be blended.

At this time, by using a diluting solvent that is erodible to the support film, the interface between the formed hard coat layer and the support film is mixed, and reflected light generated between the hard coat layer and the support film. It is possible to suppress thin film interference (interference fringes).

Also, scratch resistance can be enhanced by performing ultraviolet irradiation in a nitrogen atmosphere. The scratch resistance is evaluated, for example, by a scratch test using steel wool (# 0000, 250 g load, 10 to 100 reciprocations), and it is preferable that the hard coat surface is not scratched by the test.

The hardness of the hard coat layer is evaluated by a pencil hardness test (scratch hardness (pencil method)) based on JIS 5600-5-4. For example, when the support film on which the hard coat layer is formed is a TAC film (40 to 80 μm), the hardness generally preferably has a 750 g load of 2H or more, more preferably 750 g load, in the evaluation method. By having 4H or more, it is determined that the hard coat layer has a high hardness. However, the hardness according to the evaluation method depends not only on the film thickness of the hard coat layer but also on the physical properties such as the thickness of the supporting film as a base and the pressing hardness (easiness to be crushed), and therefore is limited to the above index. is not.

The hard coat layer 16 may contain a surface conditioner. Thereby, leveling of the applied coating liquid is promoted to form a smooth surface, and a surface with excellent surface feel can be formed as a member for a mirror display. In addition, by using a silicon-based or fluorine-based surface conditioner, antifouling and fingerprint resistance functions can be imparted to the hard coat layer 16.

[About swell degree]
When the support film 12 and other membranes are formed by a casting method, particularly when a resin diluted with a solvent is formed by the casting method, the resin and the solvent are convected in the process of removing the solvent during concentration and concentrating the concentration. Fluctuation due to convection may remain after film formation. In addition, fluctuations may occur due to the influence of wind during air drying. “Waviness” means such a state of fluctuation of film thickness fluctuation or non-uniform phase difference.

When waviness is present in the support film 12 or the adhesive layer 10 of the polarizing member 100, the liquid crystal display to which the polarizing member 100 is applied causes distortion of a display image. Therefore, it is preferable that the member used for the polarizing member 100 has a swell degree as low as possible.

The swell degree is an evaluation value for numerically evaluating the quality of the display image on the mirror display. The degree of waviness of the support film 12, the polarizing plate, the pressure-sensitive adhesive layer 10 and the like can be measured using a polarizing plate waviness inspection apparatus manufactured by Fusion Co., Ltd.

Explain the measurement of swell. A dot pattern of equal intervals is displayed on a 4K resolution monitor display, and a monitor image of the dot pattern reflected on the mirror portion is taken by a camera through a smooth mirror set at an angle of 45 degrees. This is a blank measurement. Next, an object to be measured such as a support film 12, a polarizing plate, and an adhesive layer 10 is placed between the mirror and the camera, and an image of a dot pattern when the object to be measured is transmitted is measured with the camera. At this time, the object to be measured is a flat glass plate bonded with an adhesive. By analyzing the image of the captured dot pattern, the standard deviation (Total σ) of the deviation of the dot pattern is obtained and the value is used as the undulation degree.

The swell degree is about 5 when blank. That is, as the degree of undulation is closer to 5, there is almost no undulation, and as the degree of undulation exceeds 5, the measured object has an optical distortion.

The swell degree of a general polarizing member (including a polarizing plate and an adhesive layer) applied to a liquid crystal display is 20 or more and 23 or less. When such a polarizing member is used as a member of a mirror display, the swell is more easily recognized than when the liquid crystal display is directly viewed. This is because a mirror display is often used in a mirror state with no image display, and a reflected image is observed, so that the surface shape becomes important. Therefore, if there is a wave of the polarizing member 100 serving as a mirror surface, a landscape image reflected as a reflected image looks distorted and cannot function sufficiently as a mirror display.

Therefore, the degree of undulation of the polarizing member 100 suitable for a mirror display is preferably 15 or less, and more preferably 8 or less. By setting it as such a wave | undulation degree, in a mirror display using the polarizing member 100, a high quality mirror surface with little distortion can be obtained.

In order to realize such a degree of undulation of the polarizing member 100, the support film 12 having a small degree of undulation may be used. The support film 12 may have a swell degree of 12 or less, more preferably 7 or less. The swell degree in this case is a value when measured using an adhesive layer having a swell degree of 6 or less (the adhesive layer hardly contributes). Since the degree of undulation of the support film 12 depends on its thickness, the thickness of the support film 12 may be 200 μm or less, more preferably 80 μm or less, and more preferably 40 to 60 μm.

Further, the pressure-sensitive adhesive layer 10 may have a swell degree of 7 or less.

[Durability]
Members used for automobile interiors are required to have high durability. For example, a display device such as a liquid crystal display is required to satisfy the reliability of 1000 hours or more at a dry heat test of 95 ° C. and 1000 hours or more at a wet heat test of 65 ° C. and 93%. This is based on the durability of a member such as a TFT liquid crystal display device used in the display device section. It is preferable that the polarizing member used in the display device has the same or equivalent reliability. The durability in that case is, for example, 1000 hours or more at 105 ° C. for the dry heat test and 240 hours or more at 85 ° C. and 85% for the wet heat test. Therefore, it is preferable to use a dye-based polarizing film containing a dichroic dye as the polarizing member. In addition, as an evaluation item of the durability of the polarizing member, there are, for example, changes in optical characteristics, and changes in appearance such as discoloration, peeling, and deformation.

[Preparation of Polarizing Film 14]
A polyvinyl alcohol resin film (VF-PS (75 μm) manufactured by Kuraray Co., Ltd.) was swollen in water at 30 ° C. for 5 minutes, and then dyed at 30 ° C. (1000 parts by weight of water, 0.3 parts by weight of sodium tripolyphosphate). On the other hand, 0.11 part by weight of C.I.Direct Orange 39 and 0.11 part by weight of C.I.Direct Red 81, a blue dye obtained by the method described in JP-A-3-12606 0.10 parts by weight of green dye obtained by the method described in JP-A No. 59-145255 was immersed in 0.11 part by weight for 5 minutes, followed by dyeing with the dye. The film was stretched 5.5 times in a weight% boric acid aqueous solution to obtain a stretched film, and after the stretching treatment, the stretched film was immersed in a 5 weight% boric acid aqueous solution at 50 ° C. for 2 minutes, washed with water, and air at 30 to 80 ° C. In dried to obtain a polarizing film 14 of the present disclosure. The resulting thickness of the polarizing film 14 was 30 [mu] m.

[Preparation of hard coat layer]
40 parts by weight of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30) as a polyfunctional (meth) acrylate, 60 parts by weight of methyl ethyl ketone as a solvent, and 0.2 parts by weight of an acrylic polymer leveling agent And 2 parts by weight of Irgacure 184 (manufactured by Ciba Specialty Chemicals) as a polymerization initiator were mixed to prepare a paint, which was applied to one side of a TAC film having a thickness of 60 μm by a microgravure coater. Thereafter, the solvent was removed by drying at 40 to 80 ° C. for 2 minutes, and then the coating film was irradiated with ultraviolet rays by a high-pressure mercury lamp in a nitrogen atmosphere to cure the coating film, thereby forming a hard coat layer on the TAC film. The film thickness of the obtained hard coat layer was about 5 μm. The pencil hardness of this hard coat layer was 2H at a load of 750 g.

[Preparation of polarizing plate]
A TAC film having a thickness of 60 μm was laminated on both surfaces of the polarizing film obtained by the above method using an aqueous adhesive containing polyvinyl alcohol (PVA). Then, it dried at 70 degreeC for 5 minute (s), and the polarizing plate was obtained. At this time, the TAC film with the hard coat layer obtained by the above method is used as the second support film 12b on one side to be laminated, and the TAC film without the hard coat layer is bonded to the polarizing film as the first support film 12a. did. Table 1 shows the results obtained by measuring the optical characteristics of the obtained polarizing plate using a spectrophotometer U-4100 manufactured by Hitachi, Ltd. At this time, the single transmittance Ys of the polarizing plate was 50.1%, and the polarization degree Py was 73.7%. Further, the linearly polarized light transmittance was measured using JASCO V-7100, and the transmittance waveform of the polarizing plate in the visible light region is shown in FIG.

[Preparation of adhesive layer 10]
According to a known document (Japanese Patent Laid-Open No. 2016-206468), an acrylic pressure-sensitive adhesive was applied on a release film and dried to prepare an adhesive layer 10. The pressure-sensitive adhesive layer 10 was applied to the polarizing member 100 by pasting the obtained coated surface toward the first support film 12a. Then, in order to accelerate | stimulate the crosslinking reaction of the hardening | curing agent in the adhesion layer 10, it was hold | maintained at 35 degreeC for 3 days or more, and the polarizing member 100 in a present Example was obtained.

The film thickness of the obtained adhesive layer 10 was 20 μm. Only this adhesive layer 10 was bonded on a glass plate, and the degree of undulation was 6.6 as measured by a polarizing plate undulation inspection device manufactured by Fusion Co., Ltd. In addition, the 60 μm-thick TAC film measured in the same manner was 6.5, and the undulation degree of the polarizing member 100 was 7.4.

A polyvinyl alcohol resin film (manufactured by Kuraray Co., Ltd., VF-PS (75 μm)) was swollen in water at 30 ° C. for 5 minutes, and then dyed at 30 ° C. (1000 parts by weight of water and 0.3 parts by weight of sodium tripolyphosphate). In contrast, 0.0.10 parts by weight of C.I.Direct Orange 39, 0.10 parts by weight of C.I.Red Red 81, and blue obtained by the method described in JP-A-3-12606 0.13 parts by weight of a dye and a green dye obtained by the method described in JP-A-59-145255 are immersed in 0.10 parts by weight for 5 minutes, followed by dyeing with the dye, followed by 50 ° C. The film was stretched 5.5 times in a 3% by weight boric acid aqueous solution to obtain a stretched film, and after the stretching treatment, the stretched film was immersed in a 5% by weight boric acid aqueous solution at 50 ° C. for 2 minutes, washed with water, and then 30-80 The film was dried in the air to obtain the polarizing film 14 of the present disclosure, and the thickness of the polarizing film 14 obtained was 30 μm, and the polarizing film obtained using a spectrophotometer U-4100 manufactured by Hitachi, Ltd. When the optical characteristics were measured, the single transmittance Ys was 50.1% and the polarization degree Py was 73.8% In addition, since the proportion of the blue dye was increased in the dye blend, the hue of Example 1 was It was possible to shift more blue.

The production of the polarizing plate and the production of the polarizing member are the same as those described in Example 1.

Comparative example

A commercially available polarizing member, a hard-coated iodine polarizing plate SKN-18243T-HC (manufactured by Polatechno) was used. The thickness of the product (excluding protective film and release film) is 220 μm. Specifically, the hard coat layer has a thickness of 5 μm, the support film has a thickness of 80 μm, and the adhesive layer has a thickness of 25 μm. When the optical properties of the polarizing member were measured, the single transmittance Ys was 42.8%, and the polarization degree Py was 99.9%. Further, the linearly polarized light transmittance was measured using JASCO V-7100, and the transmittance waveform of the polarizing plate in the visible light region is shown in FIG.

As in Example 1, the polarizing member was bonded onto a glass plate and the swell degree was measured. The swell degree was 22.2.

[Evaluation of optical properties]
The polarizing member of Example 1 and Comparative Example 1 is bonded to one side of a white plate glass having a thickness of 1.1 mm, and DBEF manufactured by the reflective polarizing plate 3M is used on the opposite side of the glass plate using the above-mentioned adhesive layer. An evaluation sample was prepared by pasting and making it look like a liquid crystal shutter part. At this time, samples were produced in which the relationship between the polarization axis of the polarizing member and the transmission axis of the reflective polarizing plate was orthogonal and parallel. The case of the orthogonal relationship corresponds to the mode of the mirror mode in the mirror display, and the total light reflectance of the polarizing plate member surface of the sample at this time was measured to calculate the reflection hue (a * r, b * r). The total light reflectivity Yr (unit:%) is measured using a spectrophotometer U-4100 manufactured by Hitachi, Ltd., and the polarizing member surface of the evaluation sample is installed on the white plate side of the integrating sphere with the integrating sphere side facing. It was measured. The total light reflectance Yr was obtained in the same manner as the calculation method of the formula (1).

Also, in the case of a parallel relationship, it corresponds to the mode of display mode on the mirror display. The transmittance of the sample at this time was measured, and the hue was calculated. The measurement results are shown in Table 2.

[Durability test]
The polarizing member obtained as described above was cut into a size of 45 × 40 mm (absorption axis parallel to the long side), and bonded to white plate glass (thickness: 1.1 mm) as a sample for durability test. Thereafter, the sample was put into an autoclave and subjected to a pressure treatment for 15 minutes under an atmospheric pressure of 0.5 MPa and a temperature of 60 ° C., thereby sufficiently adhering the adhesive layer of the polarizing member and the glass.

The conditions of the durability test were 105 ° C. as a dry heat test and 85 ° C. and 85% as a wet heat test, and samples were put into the respective conditions. The durability performance was evaluated by measuring the optical characteristics of the sample before and after the introduction of the durability tester using a spectrophotometer U-4100, and measuring the transmittance (Ys) and the hue (a * s, b * s) before and after the introduction. This was done by determining the amount of change (after charging-before charging).

Tables 1 to 4 and FIG. 2 show the measurement results for each Example and Comparative Example 1.

The hue values of the polarizing plates obtained from Examples 1 and 2 were smaller than those of Comparative Example 1 using an iodine polarizing plate as shown in Table 1. As shown in the spectral waveform of FIG. 2, the transmittance on the short wavelength side is improved as compared with Comparative Example 1, the waveform is flat in the entire visible light region, and a neutral hue than Comparative Example 1 can be achieved. did it. Further, by setting the single transmittance Ys to 50.1%, the linearly polarized light transmittance equivalent to that of the comparative example 1 can be obtained. Therefore, the amount of light from the display unit is not inferior to that obtained when an iodine-based polarizing plate having a high degree of polarization is used, so that the same display luminance can be obtained.

Table 2 shows the evaluation results of the optical characteristics of the evaluation sample as if it were a liquid crystal shutter. The reflectance of the mirror mode was higher than that of the polarizing member in Comparative Example 1 using an iodine-based polarizing plate. That is, in the polarizing member 100 in Example 1, the visibility in the mirror state can be improved. Further, the b * r value of the polarizing member 100 in Example 1 was lower than that in Comparative Example 1. That is, the use of the polarizing member 100 in Example 1 can suppress the coloring of the mirror. In the display mode, the polarizing member 100 in Example 1 had a small hue value in Comparative Example 1. Therefore, a small colored display image can be provided as in the mirror mode.

The durability test results are shown in Tables 3 and 4. In the dry heat test (shown in Table 3), Examples 1 and 2 have a smaller change in b * s than Comparative Example 1. In other words, even when exposed to high temperatures for a long period of time, the display is less likely to be yellow. In the wet heat test (shown in Table 4), in Examples 1 and 2, the amount of change in transmittance is small and the polarization performance is maintained, but in Comparative Example 1, the degree of polarization Py is greatly reduced and the polarization is reduced. The performance is lost.

Therefore, Examples 1 and 2 which are dye-based polarizing plates have excellent optical durability under both high temperature and high humidity conditions.

As described above, according to the polarizing member 100 in the present embodiment, since the polarizing member has a low degree of undulation, it is possible to suppress fluctuations in the display image and the reflected image. Further, by using the polarizing member 100, a liquid crystal shutter type mirror display used as a rearview mirror for automobiles or the like gives a high reflectance in the mirror mode, and also reduces the influence of coloring by the polarizing plate in the display mode. be able to. Furthermore, it is possible to provide a dye-based polarizing plate for a mirror display having excellent durability in long-term use and a mirror display using the same.

Claims

A polarizing member,
A polarizing plate having a hard coat layer on one side and an adhesive layer on the other side,
The polarizer of the polarizing plate contains at least one dichroic dye,
The polarizing plate has a single transmittance Ys whose visibility is corrected, measured for light in a wavelength region of 380 nm to 780 nm, in a range of 45% to 60% and a polarization degree Py of 50% to 95%,
The polarizing plate has a hue of a single L * a * b * color system in which a * s is −3 to +3 and b * s is −3 to +3 and two polarizing plates are used. In the hue when the polarization axes are parallel, a * p is −3 to +3 and b * p is −3 to +3.
The polarizing member according to claim 1,
The pressure-sensitive adhesive layer has a swell degree of 7 or less,
The polarizing member has a swell degree of 15 or less.
The polarizing member according to claim 1,
The dichroic dye includes a water-soluble disazo compound represented by the chemical formula (1) or a copper complex salt compound thereof.

(Wherein X represents a hydrogen atom, a methyl group, a methoxy group or an ethoxy group, Y represents a methoxy group or an ethoxy group, R 1 represents a hydrogen atom or a methyl group, R 2 represents a hydrogen atom, a methyl group,- C 2 H 4 OH group, a substituted or unsubstituted phenyl group, a phenyl group substituted with a carboxy group, and a phenyl group substituted with a sulfone group.)
The polarizing member according to claim 2,
The dichroic dye includes a water-soluble disazo compound represented by the chemical formula (2) or a copper complex salt thereof.

(Wherein X represents a hydrogen atom, a methyl group, a methoxy group or an ethoxy group, Y represents a methoxy group or an ethoxy group, R 1 represents a hydrogen atom or a methyl group, R 2 represents a hydrogen atom, a methyl group,- C 2 H 4 OH group, a substituted or unsubstituted phenyl group, a phenyl group substituted with a carboxy group, and a phenyl group substituted with a sulfone group.)
The polarizing member according to claim 1,
Used for liquid crystal shutter-type mirror displays.
The polarizing member according to claim 2,
Used for liquid crystal shutter-type mirror displays.
The polarizing member according to claim 3,
Used for liquid crystal shutter-type mirror displays.
The polarizing member according to claim 1;
A liquid crystal shutter-type mirror display comprising a shutter liquid crystal cell, a reflective polarizing plate, and an image display device arranged in this order from the viewing side.
The polarizing member according to claim 2,
A liquid crystal shutter-type mirror display comprising a shutter liquid crystal cell, a reflective polarizing plate, and an image display device arranged in this order from the viewing side.
The polarizing member according to claim 3,
A liquid crystal shutter-type mirror display comprising a shutter liquid crystal cell, a reflective polarizing plate, and an image display device arranged in this order from the viewing side.
The polarizing member according to claim 4,
A liquid crystal shutter-type mirror display comprising a shutter liquid crystal cell, a reflective polarizing plate, and an image display device arranged in this order from the viewing side.