WO2015199209A1 - Transfer material of luminance-improving film, method of preparing transfer material, luminance-improving film, method of manufacturing optical sheet member using said transfer material, and optical sheet member - Google Patents

Abstract

The present invention provides: a transfer material of a luminance-improving film which comprises a peelable temporary support, a λ/4 plate, and a reflection polarizer, in that order, and has a layer thickness of 8 µm to 30 µm, wherein the reflection polarizer includes a light-reflecting layer formed by immobilizing a cholesteric liquid crystal phase, and both the λ/4 plate and the light-reflecting layer are coated and cured layers of a polymerizable liquid crystal composition including a liquid crystal compound; a method of preparing the transfer material comprising coating the temporary support or the surface of an alignment layer provided on the surface of the temporary support with the polymerizable liquid crystal composition including the liquid crystal compound, and then curing the coated layer thus obtained to form the λ/4 plate; a luminance-improving film obtained by peeling the temporary support from the transfer material; a method of manufacturing an optical sheet member comprising attaching, to a polarizing plate, a peeled surface obtained by peeling the temporary support from the transfer material; and an optical sheet member obtained by the abovementioned manufacturing method. A thin-film optical sheet member can be provided using the transfer material according to the present invention.

Description

Brightness-enhancement film transfer material, transfer material production method, brightness-enhancement film, optical sheet member manufacturing method using transfer material, and optical sheet member

The present invention relates to a transfer material for a brightness enhancement film. The present invention also relates to a method for producing the transfer material, and further relates to a method for producing an optical sheet member using the transfer material, an optical sheet member, and a brightness enhancement film obtained from the transfer material.

Flat panel displays such as liquid crystal display devices (hereinafter also referred to as LCDs) are often used especially for small sizes such as tablet PCs and smartphones, and in recent years, they are increasingly required to be thinner.
On the other hand, the liquid crystal display device has a basic configuration in which a backlight (hereinafter also referred to as BL), a backlight side polarizing plate, a liquid crystal cell, and a viewing side polarizing plate are provided in this order. It has been proposed to provide a reflective polarizer between the backlight and the backlight side polarizing plate of this configuration. The reflective polarizer is an optical element that transmits only light oscillating in a specific polarization direction among light incident while oscillating in all directions, and reflects light oscillating in other polarization directions. This makes it possible to recycle the light that is reflected without being reflected by the reflective polarizer, thereby improving the light utilization efficiency in the LCD. As the reflective polarizer, Patent Document 1 discloses a film known as DBEF (registered trademark) (Dual Brightness Enhancement Film), and Patent Documents 2 to 4 include a λ / 4 plate and a cholesteric liquid crystal phase. A film having a structure in which fixed layers are laminated is described.

Japanese Patent No. 3448626 JP-A-1-133003 Japanese Patent No. 3518660 WO2008 / 016056

When the film functioning as a reflective polarizer as described above is used as a component for an LCD as a brightness enhancement film, the present inventors have attempted to make the brightness enhancement film thinner so that the LCD can be made thinner. However, when the thinned brightness enhancement film is bonded to a polarizer, a problem of bending (bending) occurs.
The subject of this invention is providing the material which enables manufacture of the optical sheet member of a thin film as an optical sheet member which can be used for LCD etc. More specifically, an object of the present invention is to provide a transfer material capable of providing a thin film brightness enhancement film that hardly causes a problem of bending even when used by being attached to a polarizing plate.

As a result of the study by the present inventors, when a brightness enhancement film having a thin layer including a layer formed by polymer stretching is used for a polarizing plate including a polarizer obtained by stretching such as polyvinyl alcohol, the influence of heat and humidity It was found that shrinkage occurred on both sides and the polarizing plate was greatly warped. The inventors of the present invention have further studied earnestly about the structure of the brightness enhancement film which hardly causes such shrinkage, and completed the present invention.

That is, the present invention provides the following [1] to [20].
[1] A transfer material for a brightness enhancement film,
The brightness enhancement film has a thickness of 4 μm or more and 30 μm or less,
The transfer material includes a peelable temporary support, a λ / 4 plate, and a reflective polarizer in this order,
The reflective polarizer includes a light reflecting layer formed by fixing a cholesteric liquid crystal phase,
The λ / 4 plate and the light reflecting layer are both transfer materials that are coating and curing layers of a polymerizable liquid crystal composition containing a liquid crystal compound.
[2] The reflective polarizer includes at least two light reflective layers,
The transfer material according to [1], wherein at least two adjacent layers selected from the group consisting of at least two light reflecting layers and the λ / 4 plate are in direct contact with each other.
[3] The transfer material according to [2], wherein one layer of the light reflecting layer is in direct contact with the λ / 4 plate.
[4] The transfer material according to any one of [1] to [3], wherein the film thickness of the brightness enhancement film is 15 μm or less.
[5] The transfer material according to any one of [1] to [4], wherein the temporary support is selected from the group consisting of a cellulose acylate film and a polyester film.
[6] including an alignment layer;
The transfer material according to any one of [1] to [5], comprising the temporary support, the alignment layer, the λ / 4 plate, and the reflective polarizer in this order.
[7] The transfer material according to [6], wherein the temporary support and the alignment layer are in direct contact, and the alignment layer contains polyvinyl alcohol.
[8] The transfer material according to [7], wherein the temporary support is an unsaponified cellulose acylate film.
[9] The reflection polarizer according to [1] to [8], wherein the reflective polarizer includes a coating / curing layer of a polymerizable liquid crystal composition including a discotic liquid crystal compound and a coating / curing layer of a polymerizable liquid crystal composition including a rod-shaped liquid crystal compound. The transfer material according to any one of the above.
[10] The transfer material according to any one of [1] to [9], wherein Δn of the rod-like liquid crystal compound is 0.2 or more.

[11] Any one of [1] to [10], wherein the helical pitch of the cholesteric liquid crystal phase with the coating / curing layer of the polymerizable liquid crystal composition containing the rod-like liquid crystal compound is continuously changed in the film thickness direction The transfer material according to Item.
[12] A method for producing a transfer material according to any one of [1] to [11],
The λ / 4 plate is formed by applying a polymerizable liquid crystal composition containing a liquid crystal compound to the surface of the temporary support or the alignment layer provided on the surface of the temporary support, and curing the resulting coating film. Manufacturing method.
[13] The production method according to [12], including forming the light reflecting layer by curing a coating film obtained by coating a polymerizable liquid crystal composition containing a liquid crystal compound on the surface of the λ / 4 plate. .
[14] A brightness enhancement film obtained by peeling the temporary support from the transfer material according to any one of [1] to [5], wherein the λ / 4 plate and the reflective polarizer are A brightness enhancement film including an outermost surface of the λ / 4 plate.
[15] A brightness enhancement film obtained by peeling the temporary support from the transfer material according to [7] or [8], wherein the alignment layer, the λ / 4 plate, and the reflective polarizer are A brightness enhancement film including the order and the outermost surface being the orientation layer.
[16] peeling off the temporary support of the transfer material according to any one of [1] to [11],
The manufacturing method of the optical sheet member including bonding together the peeling surface obtained by the said peeling to the polarizing plate containing a polarizer with an adhesive agent.
[17] The production method according to [16], wherein the polarizer includes polyvinyl alcohol, the release surface is bonded to the surface of the polarizer with an adhesive, and the adhesive includes polyvinyl alcohol.
[18] An optical sheet member including the brightness enhancement film according to [14] and a polarizing plate including a polarizer, wherein the λ / 4 plate and the polarizer are directly bonded with an adhesive layer. Sheet member.
[19] An optical sheet member including the brightness enhancement film according to [15] and a polarizing plate including a polarizer, wherein the alignment layer and the polarizer are directly bonded by an adhesive layer. .
[20] The optical sheet member according to [19], wherein both the polarizer and the adhesive layer contain polyvinyl alcohol.

According to the present invention, a transfer material for a brightness enhancement film capable of producing a thin brightness enhancement film is provided. More specifically, according to the present invention, there is provided a transfer material capable of providing a thin-film brightness enhancement film that hardly causes a bending problem even when attached to a polarizer. By using the transfer material of the present invention, it is possible to provide a thinner optical film material having brightness enhancement performance. The optical film material can be used as a constituent member of a liquid crystal display device.

It is a figure which shows the example of the layer structure of a transfer material. It is a figure which shows the example of a layer structure of an optical sheet member.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, the “half width” of a peak means the width of the peak at a peak height of 1/2. The reflection center wavelength and half width of the light reflection layer can be obtained as follows.
When the transmission spectrum of the light reflection layer is measured using a spectrophotometer UV3150 (Shimadzu Corporation), a peak of decrease in transmittance is observed in the selective reflection region. Of the two wavelengths having a transmittance of 1/2 the maximum peak height, the wavelength value on the short wave side is λ1 (nm) and the wavelength value on the long wave side is λ2 (nm). The reflection center wavelength and the half width can be expressed by the following formula.
Reflection center wavelength = (λ1 + λ2) / 2
Half width = (λ2-λ1)

In the present specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. The unit is nm. Re (λ) is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film. In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like. When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method. This measuring method is also partially used for measuring the average tilt angle on the alignment layer side of the discotic liquid crystal molecules in the optically anisotropic layer, which will be described later, and the average tilt angle on the opposite side.
Rth (λ) is the above-mentioned Re (λ) with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis) (if there is no slow axis, film A total of 6 points of light having a wavelength λ nm are incident in 10 degree steps from the normal direction to 50 ° on one side with respect to the normal direction of the film (arbitrary direction in the plane). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value. In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative. The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (A) and formula (B) based on the value, the assumed value of the average refractive index, and the input film thickness value.

Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula (A), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz is the direction orthogonal to nx and ny. Represents the refractive index. d is the film thickness.
Rth = ((nx + ny) / 2−nz) × d Expression (B)

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method. Rth (λ) is −50 ° with respect to the normal direction of the film, using Re (λ) described above as the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis). Then, 11 points of light having a wavelength of λ nm are incident in 10 ° steps from 1 ° to + 50 °, and the measured retardation value, average refractive index assumption and input film thickness value are used as the basis. Calculated by KOBRA 21ADH or WR. In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

In the light reflection layer formed by fixing the cholesteric liquid crystal phase, when the normal ordinary refractive index no and the extraordinary refractive index ne of the liquid crystal are used, the average value of the in-plane refractive index is (nx + ny) / 2 = (no + ne) / 2
It is represented by
Further, since the refractive index in the film thickness direction is no, Rth of the light reflecting layer formed by fixing the cholesteric liquid crystal phase can be expressed by the following formula. In this specification, Rth of a layer formed by fixing a cholesteric liquid crystal phase is a value calculated using the following formula.
Rth = {(no + ne) / 2−no} × d = {(ne−no) / 2} × d
Note that ne and no can be measured with an Abbe refractometer.

In addition, as a method for obtaining Rth of a layer formed by fixing a cholesteric liquid crystal phase, a method using a polarization ellipso can be applied.
For example, the Kimura et al. Jpn. J. et al. Appl. Phys. 48 (2009) When the ellipsometry method is used as described in 03B021, the thickness of the layer formed by fixing the cholesteric liquid crystal phase, the pitch of the helical structure, the twist angle, and the like can be obtained. Obtainable.

In this specification, “visible light” means 380 nm to 780 nm. Moreover, in this specification, when there is no special mention about a measurement wavelength, a measurement wavelength is 550 nm.
Further, in the present specification, regarding the angle (for example, an angle such as “90 °”) and the relationship (for example, “orthogonal”, “parallel”, “crossing at 45 °”, etc.), the technical field to which the present invention belongs. The range of allowable error is included. For example, it means that the angle is within the range of strict angle ± 10 °, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.

In this specification, the “absorption axis” and “transmission axis” of a polarizer or a polarizing plate mean directions that form an angle of 90 ° with each other.
In the present specification, the “slow axis” of a retardation film or the like means a direction in which the refractive index is maximized.
Further, in this specification, numerical values, numerical ranges, and qualitative expressions (for example, “equivalent”, “equal”, etc.) indicating optical characteristics of each member such as a retardation region, a retardation film, and a liquid crystal layer are used. ) Is interpreted to indicate numerical values, numerical ranges and properties including generally allowable errors for liquid crystal display devices and members used therefor.
Further, in this specification, “front” means a normal direction to the display surface.

In the present specification, the brightness enhancement film means a film including a λ / 4 plate and a reflective polarizer.
In this specification, the reflective polarizer means a layer including a light reflection layer formed by fixing a cholesteric liquid crystal phase, and is used separately from the polarizer.

[Transfer material for brightness enhancement film]
The brightness enhancement film transfer material (hereinafter referred to as “transfer material”) is a material capable of transferring the brightness enhancement film to another member. Examples of other members include a polarizing plate.
The transfer material includes a peelable temporary support and a brightness enhancement film. That is, the transfer material includes a temporary support, a λ / 4 plate, and a reflective polarizer. In the transfer material, the temporary support, the λ / 4 plate, and the reflective polarizer are arranged in this order. It is preferable that at least two adjacent layers selected from the group consisting of at least two light reflecting layers and a λ / 4 plate are in direct contact with each other. Further, it is preferable that one layer of the light reflecting layer is in direct contact with the λ / 4 plate.
FIG. 1 shows an example of the layer structure of the transfer material. In FIG. 1, the alignment layer is not considered except for the alignment layer between the temporary support and the λ / 4 plate. In the drawing, the light reflecting layer in the transfer material including a plurality of light reflecting layers includes the first light reflecting layer (14a), the second light reflecting layer (14b), and the third light reflecting layer from the λ / 4 plate side. Shown as layer (14c).
The brightness enhancement film contained in the transfer material is a thin film and has a thickness of 4 μm or more and 30 μm or less. In this range, flexibility can be maintained. The film thickness is preferably 27 μm or less, and more preferably 15 μm or less. The film thickness is preferably 5 μm or more, and more preferably 8 μm or more.

<Temporary support>
In the present specification, the temporary support means a support that can be peeled off from a layer (λ / 4 plate or alignment layer) provided thereon. The temporary support and the alignment layer provided on the surface thereof may be integrally peelable. Being peelable means that the optical properties and film surface state of the brightness enhancement film can be separated without changing them to an extent that affects use.
The temporary support is not particularly limited and may be rigid or flexible, but is preferably flexible in terms of easy handling. The rigid support is not particularly limited, but is a known glass plate such as a soda glass plate having a silicon oxide film on its surface, a low expansion glass, a non-alkali glass, a quartz glass plate, a metal such as an aluminum plate, an iron plate, or a SUS plate. A board, a resin board, a ceramic board, a stone board, etc. are mentioned.
Examples of the flexible support include polymer film, paper, aluminum foil, and cloth.
Examples of polymer films include cellulose acylate films (for example, cellulose triacetate film, cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyethylene, polypropylene, and polymers having an alicyclic structure (norbornene resin). (Arton: trade name, manufactured by JSR, amorphous polyolefin (Zeonex: trade name, manufactured by Nippon Zeon)), etc., polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films , Polyacrylic resin film such as polymethylmethacrylate, polyurethane resin film, polycarbonate film, polystyrene and acrylo Examples thereof include styrene polymers such as tolyl / styrene copolymer (AS resin), among which cellulose acylate film, polyester resin film, polyolefin resin film, polycarbonate film, or styrene polymer are preferable. A rate film and a polyester resin film are more preferable, a cellulose triacetate film or a polyethylene terephthalate film (PET) is more preferable, and a cellulose triacetate film is particularly preferable.
In view of ease of handling, the thickness of the rigid support is preferably from 100 to 3000 μm, and more preferably from 300 to 1500 μm. The film thickness of the flexible support may be about 5 μm to 1000 μm, preferably 10 μm to 250 μm, more preferably 15 μm to 90 μm.

In order to make the temporary support and the layer (λ / 4 plate or alignment layer) provided thereon peelable, the temporary support is subjected to surface treatment (eg, saponification treatment, glow discharge treatment, corona discharge treatment, It is preferable not to perform ultraviolet (UV) treatment or flame treatment. That is, for example, an unsaponified cellulose acylate film is preferable as a temporary support.
In order to make the temporary support and the layer provided thereon peelable, it is also preferable to select the layer provided thereon according to the selected temporary support material and adjust the composition.
In addition, the long temporary support is provided with inorganic particles having an average particle size of about 10 to 100 nm in order to provide slippage in the conveying process and to prevent sticking between the back surface and the surface after winding. It is preferable to use a polymer layer in which 5% to 40% of the solid content is mixed and formed on one side of the temporary support by coating or co-casting with the temporary support.

<Λ / 4 plate>
The λ / 4 plate has an in-plane retardation Re (λ) at a specific wavelength λnm. Re (λ) = λ / 4
An optically anisotropic layer satisfying the above. The above equation may be achieved at any wavelength in the visible light range (for example, 550 nm). In the brightness enhancement film, the λ / 4 plate functions as a layer for converting circularly polarized light obtained by passing through the reflective polarizer into linearly polarized light.

The λ / 4 plate includes a coating / curing layer of a polymerizable liquid crystal composition containing a liquid crystal compound. In the present specification, the coating / curing layer means a layer obtained by curing a polymerizable liquid crystal composition coated on the layer. The λ / 4 plate is a layer showing optical anisotropy expressed by the orientation of molecules of the liquid crystal compound.

The type of liquid crystal compound used for forming the λ / 4 plate is not particularly limited. For example, an optically anisotropic layer obtained by forming a low-molecular liquid crystal compound in a nematic alignment in a liquid crystal state and then fixing by photocrosslinking or thermal cross-linking, or a polymer liquid crystal compound in a nematic alignment in a liquid crystal state and then cooling. Accordingly, an optically anisotropic layer obtained by fixing the orientation can also be used. In the present invention, even when a liquid crystal compound is used for the optically anisotropic layer, the optically anisotropic layer is a layer formed by fixing the liquid crystal compound by polymerization or the like, and thus becomes a layer. After that, it is no longer necessary to show liquid crystallinity. The polymerizable liquid crystal compound may be a polyfunctional polymerizable liquid crystal or a monofunctional polymerizable liquid crystal compound. The liquid crystal compound may be a discotic liquid crystal compound or a rod-like liquid crystal compound, but a discotic liquid crystal compound is more preferable.

In the λ / 4 plate, it is preferable that the molecules of the liquid crystal compound are fixed in any alignment state of vertical alignment, horizontal alignment, hybrid alignment, and tilt alignment. In order to produce a retardation plate having a symmetric viewing angle dependency, the disk surface of the disk-like liquid crystal compound is substantially perpendicular to the film surface (optically anisotropic layer surface), or a rod-like liquid crystal It is preferable that the long axis of the compound is substantially horizontal with respect to the film surface (optically anisotropic layer surface). The term “substantially perpendicular to the discotic liquid crystal compound” means that the average angle between the film surface (optically anisotropic layer surface) and the disc surface of the discotic liquid crystal compound is in the range of 70 ° to 90 °. To do. 80 ° to 90 ° is more preferable, and 85 ° to 90 ° is still more preferable. That the rod-like liquid crystal compound is substantially horizontal means that the angle formed by the film surface (optically anisotropic layer surface) and the director of the rod-like liquid crystal compound is in the range of 0 ° to 20 °. 0 ° to 10 ° is more preferable, and 0 ° to 5 ° is still more preferable.

The λ / 4 plate is composed of a liquid crystal compound such as a rod-like liquid crystal compound or a disk-like liquid crystal compound, and a polymerizable liquid crystal composition containing a polymerization initiator, an alignment control agent, other additives or a solvent, if desired, on a temporary support. It can form by apply | coating to and hardening the coating film obtained. The polymerizable liquid crystal composition may be applied on the surface of the temporary support, or may be formed on the surface of the alignment layer by forming an alignment layer on the temporary support.
Each component, coating method, and curing method of the polymerizable liquid crystal composition for forming the λ / 4 plate are the same as each component, coating method, and curing method in the polymerizable liquid crystal composition for forming the light reflection layer. However, the polymerizable liquid crystal composition for forming the λ / 4 plate preferably does not contain a chiral agent.

The film thickness of the λ / 4 plate may be 1 to 10 μm, and preferably 1 to 5 μm.
The λ / 4 plate preferably satisfies at least one of the following formulas (A) to (C), and more preferably satisfies all of the following formulas (A) to (C).

Formula (A) 450 nm / 4-35 nm <Re (450) <450 nm / 4 + 35 nm
Formula (B) 550 nm / 4-35 nm <Re (550) <550 nm / 4 + 35 nm
Formula (C) 630 nm / 4-35 nm <Re (630) <630 nm / 4 + 35 nm
Further, Rth (550) of the λ / 4 plate is preferably −120 to 120 nm, more preferably −80 to 80 nm, and particularly preferably −70 to 70 nm.

More preferably, the λ / 4 plate satisfies the following formulas (1) to (3).
Formula (1) 450nm / 4-25nm <Re (450) <450nm / 4 + 25nm
Formula (2) 550 nm / 4-25 nm <Re (550) <550 nm / 4 + 25 nm
Formula (3) 630 nm / 4-25 nm <Re (630) <630 nm / 4 + 25 nm
More preferably, the λ / 4 plate satisfies the following formulas (101) to (103).
Formula (101) 450 nm / 4-15 nm <Re (450) <450 nm / 4 + 15 nm
Formula (102) 550 nm / 4-15 nm <Re (550) <550 nm / 4 + 15 nm
Formula (103) 630 nm / 4-15 nm <Re (630) <630 nm / 4 + 15 nm
The λ / 4 plate described above preferably satisfies the following formulas (201) to (203).
Formula (201) 450 nm / 4-5 nm <Re (450) <450 nm / 4 + 5 nm
Formula (202) 550 nm / 4-5 nm <Re (550) <550 nm / 4 + 5 nm
Formula (203) 630 nm / 4-5 nm <Re (630) <630 nm / 4 + 5 nm

The λ / 4 plate preferably satisfies the following formulas (401) to (403).
Formula (401) Re (450) <Re (550) <Re (630)
Formula (402) Re (450) <Re (550) <Re (630)
Formula (403) Re (450) <Re (550) <Re (630)

<Light reflection layer>
The light reflecting layer is a layer formed by fixing a cholesteric liquid crystal layer, and is a coating / curing layer obtained by curing a coating film after coating a polymerizable liquid crystal composition containing a liquid crystal compound on another layer.
The polymerizable liquid crystal composition for forming the light reflecting layer contains a liquid crystal compound. The polymerizable liquid crystal composition for forming the light reflecting layer includes a chiral agent, an alignment controller, a polymerization initiator, an alignment aid, and the like. Other components may be contained.
The light reflection layer is formed by applying the polymerizable liquid crystal composition to other layers such as a λ / 4 plate, another light reflection layer, a temporary support (a temporary support other than the temporary support constituting the transfer material), and an alignment layer. After coating, the coating film can be obtained by curing.
The thickness of the light reflecting layer is preferably 1.5 to 8 μm, more preferably 1.5 to 5 μm, and preferably 2 to 4 μm from the viewpoints of reflectivity, orientation disorder and prevention of transmittance reduction. More preferred is 2 to 3 μm.
Each component, coating method, and curing method of the polymerizable liquid crystal composition for forming the light reflecting layer are the same as each component, coating method, and curing method in the polymerizable liquid crystal composition for forming the λ / 4 plate. However, the polymerizable liquid crystal composition for forming the light reflecting layer preferably contains a chiral agent. In forming the light reflecting layer, the polymerizable liquid crystal composition is cured after forming a cholesteric liquid crystal phase, and a liquid crystal layer formed by fixing the cholesteric liquid crystal phase is produced.

Hereinafter, each component of the polymerizable liquid crystal composition that can be used for forming the λ / 4 plate and the light reflecting layer and a method for producing the layer will be described.

<Liquid crystal compound>
Examples of the liquid crystal compound include a rod-like liquid crystal compound and a disk-like liquid crystal compound.
Examples of the rod-like liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. In addition to the above low-molecular liquid crystalline molecules, high-molecular liquid crystalline molecules can also be used.

It is more preferable to fix the orientation of the rod-like liquid crystal compound by polymerization, and examples of the polymerizable rod-like liquid crystal compound include those described in Makromol. Chem. 190, 2255 (1989), Advanced Materials, 5, 107 (1993), U.S. Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, WO 95/22586, 95/24455, 97/97. No. 0600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, JP-A-2001-328773, etc. The compounds described in the publication can be used. Further, as the rod-like liquid crystal compound, for example, those described in JP-A-11-513019 and JP-A-2007-279688 can be preferably used.

As the discotic liquid crystal compound, for example, those described in JP-A-2007-108732 and JP-A-2010-244038 can be preferably used, but are not limited thereto.
Although the preferable example of a disk shaped liquid crystal compound is shown below, this invention is not limited to these.

(Δn of liquid crystal compound)
By using the high Δn liquid crystal compound, the reflection of the light reflection layer formed by fixing the cholesteric liquid crystal phase can be broadened. For example, in the case of a rod-like liquid crystal compound, Δn is the difference in refractive index between the minor axis and the major axis of the compound.
The liquid crystal compound used in the light reflection layer formed by fixing the cholesteric liquid crystal phase is practically about 0.06 ≦ Δn ≦ 0.5 (the high Δn liquid crystal material described in JP 2011-510915 A can be used). Yes, corresponding to 15 to 150 nm in half width. Examples of the high Δn liquid crystal compound include Japanese Patent No. 3999400, Japanese Patent No. 4053782, Japanese Patent No. 4947676, and the like, but are not limited thereto. There are methods for measuring Δn, such as paragraph [0112] of Japanese Patent No. 4053778 and paragraph [0142] of Japanese Patent No. 4947676.
In the case where it is necessary to expand the reflection half-value width and reduce the film thickness in a layer to which the pitch gradient method described later is applied, Δn (birefringence) of the liquid crystal compound is preferably 0.16 or more, more preferably 0. .2 or more, more preferably 0.3 or more, and particularly preferably about 0.5, which is the upper limit of Δn of currently commercialized liquid crystals. However, if further high Δn liquid crystals are developed in the future, they can be used and the film thickness can be further reduced.
(Preferred direction of Δn dispersion)
It is known that Δn dispersion of a liquid crystal compound preferably has less dispersion at each wavelength. Δn (450/550 ratio) ≦ 1.6 is preferable, Δn (450/550 ratio) ≦ 1.4 is more preferable, Δn (450/550 ratio) ≦ 1.2 or less is further preferable, and Δn (450/550) Ratio) ≦ 1.1 is particularly preferred.

<Chiral agent>
As the chiral agent, various known chiral agents (for example, described in Liquid Crystal Device Handbook, Chapter 3-4-3, TN, chiral agent for STN, page 199, edited by Japan Society for the Promotion of Science, 42nd Committee, 1989) You can choose from. A chiral agent generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound containing no asymmetric carbon atom can also be used as the chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group. When the chiral agent has a polymerizable group and the rod-shaped liquid crystal compound used in combination also has a polymerizable group, it is derived from the rod-shaped liquid crystal compound by a polymerization reaction between the chiral agent having a polymerizable group and the polymerizable rod-shaped liquid crystal compound. And a polymer having a repeating unit derived from a chiral agent. In this embodiment, the polymerizable group possessed by the chiral agent having a polymerizable group is preferably the same group as the polymerizable group possessed by the polymerizable rod-like liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Particularly preferred.
The chiral agent may be a liquid crystal compound.
Examples of the chiral agent exhibiting a strong twisting force include, for example, JP 2010-181852 A, JP 2003-287623 A, JP 2002-80851 A, JP 2002-80478 A, and JP 2002-302487 A. The chiral agent described in the gazette is mentioned, and can be preferably used. Furthermore, isosorbide compounds having a corresponding structure can be used for the isosorbide compounds described in these publications, and isosorbide compounds having a corresponding structure can be used for the isomannide compounds described in these publications. It can also be used.

<Orientation control agent>
Examples of the alignment control agent include compounds exemplified in [0092] and [0093] of JP-A No. 2005-99248, and [0076] to [0078] and [0082] of JP-A No. 2002-129162. To [0085], the compounds exemplified in JP-A-2005-99248, [0094] and [0095], and JP-A-2005-99248, [0096]. Are included.
A compound represented by the following general formula (I) is also preferred as the fluorine-based alignment control agent.

In the general formula (I), L ¹¹ , L ¹³ , L ¹³ , L ¹⁴ , L ¹⁵ and L ¹⁵ are each independently a single bond, —O—, —S—, —CO—, —COO—, —OCO. —, —COS—, —SCO—, —NRCO—, —CONR— (in the general formula (I), R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), —NRCO—, — CONR- has the effect of reducing the solubility, and has a tendency to increase the haze value at the time of film production, and more preferably -O-, -S-, -CO-, -COO-, -OCO-, -COS- —SCO—, and —O—, —CO—, —COO—, and —OCO— are more preferable from the viewpoint of the stability of the compound. The alkyl group that R can take may be linear or branched. The number of carbon atoms is more preferably 1 to 3, and examples thereof include a methyl group, an ethyl group, and an n-propyl group.

<Polymerization initiator>
Examples of the polymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. An acyloin compound (described in US Pat. No. 2,722,512), a polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of a triarylimidazole dimer and p-aminophenyl ketone (US Pat. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970), acylphosphine oxides Compound (Japanese Patent Publication No. 63-407) No. 99, JP-B-5-29234, JP-A-10-95788, JP-A-10-29997) and the like.

<Solvent>
The polymerizable liquid crystal composition may contain a solvent. As a solvent of the composition for forming each light reflection layer, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

<Application and curing of polymerizable liquid crystal composition>
The application of the polymerizable liquid crystal composition is carried out by using a suitable liquid crystal composition such as a roll coating method, a gravure printing method, a spin coating method, etc. It can be performed by a method of developing by a method. Furthermore, it can be performed by various methods such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method. In addition, a coating film can be formed by discharging a liquid crystal composition from a nozzle using an inkjet apparatus.
Thereafter, the polymerizable liquid crystal composition is cured to fix the alignment state of the molecules of the liquid crystal compound. Curing is preferably carried out by a polymerization reaction of a polymerizable group introduced into a liquid crystal molecule.
The coating film may be dried by a known method after the application of the polymerizable liquid crystal composition and before the polymerization reaction for curing. For example, it may be dried by standing or may be dried by heating.
The liquid crystal compound molecules in the polymerizable liquid crystal composition only need to be aligned in the steps of applying and drying the polymerizable liquid crystal composition.
For example, in an embodiment in which the polymerizable liquid crystal composition is prepared as a coating liquid containing a solvent, the coating film may be dried and the solvent may be removed to obtain a cholesteric liquid crystal phase. Further, heating at a transition temperature to the cholesteric liquid crystal phase may be performed. For example, the cholesteric liquid crystal phase can be stably formed by heating to the temperature of the isotropic phase and then cooling to the cholesteric liquid crystal phase transition temperature. The liquid crystal phase transition temperature of the aforementioned polymerizable liquid crystal composition is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C., from the viewpoint of production suitability and the like. When the temperature is lower than 10 ° C., a cooling step or the like may be required to lower the temperature to a temperature range exhibiting a liquid crystal phase. When the temperature exceeds 200 ° C., a high temperature is required to make the isotropic liquid state higher than the temperature range once exhibiting the liquid crystal phase, which is disadvantageous from waste of thermal energy, deformation of the substrate, and alteration.

The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred. It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. The irradiation energy is preferably 20 mJ / cm ² to 50 J / cm ² , and more preferably 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

In order to accelerate the curing reaction, ultraviolet irradiation may be performed under heating conditions. In particular, when forming the light reflecting layer, it is preferable to maintain the temperature at the time of ultraviolet irradiation within a temperature range exhibiting a cholesteric liquid crystal phase so that the cholesteric liquid crystal phase is not disturbed.
Also, since the oxygen concentration in the atmosphere is related to the degree of polymerization, if the desired degree of polymerization is not reached in the air and the film strength is insufficient, the oxygen concentration in the atmosphere is reduced by a method such as nitrogen substitution. It is preferable. A preferable oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less. The reaction rate of the curing reaction (for example, polymerization reaction) that proceeds by irradiation with ultraviolet rays is 70% or more from the viewpoint of maintaining the mechanical strength of the layer and suppressing unreacted substances from flowing out of the layer. Preferably, it is 80% or more, more preferably 90% or more. In order to improve the reaction rate, a method of increasing the irradiation amount of ultraviolet rays to be irradiated and polymerization under a nitrogen atmosphere or heating conditions are effective. Moreover, after superposing | polymerizing once, the method of hold | maintaining at a temperature higher than superposition | polymerization temperature, and pushing a reaction further by thermal polymerization reaction, and the method of irradiating an ultraviolet-ray again can also be used. The reaction rate can be measured by comparing the absorption intensity of the infrared vibration spectrum of a reactive group (for example, a polymerizable group) before and after the reaction proceeds.

It is sufficient that the optical properties based on the orientation of the liquid crystal compound molecules of the polymerizable liquid crystal composition, for example, the optical properties of the cholesteric liquid crystal phase are retained in the layer, and the cured λ / 4 plate or light reflection The liquid crystal composition of the layer no longer needs to exhibit liquid crystallinity. For example, the liquid crystal composition may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.

In the formation of the light reflection layer, the cholesteric liquid crystal phase is fixed by the above-described curing, and the light reflection layer is formed. Here, the state in which the liquid crystal phase is “fixed” is the most typical and preferred mode in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. However, it is not limited to this. Specifically, in a temperature range of 0 ° C. to 50 ° C., or -30 ° C. to 70 ° C. under severe conditions, this layer has no fluidity and is oriented by an external field or external force. It shall mean a state in which the fixed orientation form can be kept stable without causing a change in form.
Other methods for producing a light reflecting layer having a fixed cholesteric liquid crystal phase include, for example, the methods described in JP-A-1-133003, JP-A-3416302, JP-A-3363565, and JP-A-8-271731. You may refer to it.

<Alignment layer>
The transfer material and the brightness enhancement film may include an alignment layer. The alignment layer is used to align the molecules of the liquid crystal compound in the polymerizable composition when the λ / 4 plate or the light reflection layer is formed.
The alignment layer is used in forming the λ / 4 plate or the light reflection layer, and the transfer material or the brightness enhancement film may or may not include the alignment layer. Further, when the transfer material includes an alignment layer between the temporary support and the λ / 4 plate, the alignment layer may or may not be included in the brightness enhancement film. That is, the temporary support may be peeled off at the interface between the temporary support and the alignment layer, or may be peeled off at the interface between the alignment layer and the λ / 4 plate.

The alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique vapor deposition of an inorganic compound such as SiO, or formation of a layer having microgrooves. Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.
Depending on the lower layer material such as the temporary support, the λ / 4 plate, or the light reflecting layer, the lower layer may be directly aligned (for example, rubbed) to function as the alignment layer without providing the alignment layer. it can. An example of such a temporary support as a lower layer is PET.
Further, when the light reflecting layer is laminated directly on the light reflecting layer, the lower light reflecting layer may behave as an alignment layer, and the liquid crystal compound for producing the upper light reflecting layer may be aligned. In such a case, the upper liquid crystal compound can be aligned without providing an alignment layer or without performing a special alignment process (for example, rubbing process).
Hereinafter, a rubbing-treated alignment layer and a photo-alignment layer used by rubbing the surface as preferred examples will be described.

(Rubbing alignment layer)
Examples of the polymer that can be used for the rubbing treatment oriented layer include, for example, a methacrylate copolymer, a styrene copolymer, a polyolefin, polyvinyl alcohol, and the like described in paragraph No. [0022] of JP-A-8-338913. Examples include modified polyvinyl alcohol, poly (N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, and polycarbonate. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. .

The aforementioned composition is applied to the rubbing-treated surface of the alignment layer to align the molecules of the liquid crystal compound. Thereafter, if necessary, the alignment layer polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment layer polymer is crosslinked using a crosslinking agent, thereby the optical anisotropy described above. A layer can be formed.
The film thickness of the alignment layer is preferably in the range of 0.1 to 10 μm.

-Rubbing treatment-
The surface of the alignment layer, temporary support, λ / 4 plate, or light reflection layer to which the polymerizable liquid crystal composition is applied may be rubbed as necessary. The rubbing treatment can be generally performed by rubbing the surface of a film containing a polymer as a main component with paper or cloth in a certain direction. A general method of rubbing is described in, for example, “Liquid Crystal Handbook” (issued by Maruzen, October 30, 2000).

As a method for changing the rubbing density, a method described in “Liquid Crystal Handbook” (published by Maruzen) can be used. The rubbing density (L) is quantified by the following formula (A).
Formula (A) L = Nl (1 + 2πrn / 60v)
In the formula (A), N is the number of rubbing, l is the contact length of the rubbing roller, r is the radius of the roller, n is the number of rotations (rpm) of the roller, and v is the stage moving speed (second speed).

In order to increase the rubbing density, the rubbing frequency should be increased, the contact length of the rubbing roller should be increased, the radius of the roller should be increased, the rotation speed of the roller should be increased, and the stage moving speed should be decreased, while the rubbing density should be decreased. To do this, you can reverse this. In addition, the description in Japanese Patent No. 4052558 can also be referred to as conditions for the rubbing process.

(Photo-alignment layer)
A large number of literatures describe the photo-alignment material used for the photo-alignment layer formed by light irradiation. For example, JP 2006-285197 A, JP 2007-76839 A, JP 2007-138138 A, JP 2007-94071 A, JP 2007-121721 A, JP 2007-140465 A, Azo compounds described in JP 2007-156439 A, JP 2007-133184 A, JP 2009-109831 A, JP 3888848 A, Patent 4151746 Aroma described in JP 2002-229039 A Group ester compounds, maleimide and / or alkenyl-substituted nadiimide compounds having photo-alignment units described in JP-A Nos. 2002-265541 and 2002-31703, and light described in JP-A-4205195 and JP-A-4205198 Crosslinkable silane derivative, special 2003-520878, JP-T-2004-529220 and JP-mentioned as photocrosslinkable polyimide, polyamide or ester are preferable examples described in Japanese Patent No. 4162850. Particularly preferred are azo compounds, photocrosslinkable polyimides, polyamides, or esters.

The photo-alignment layer formed from the above material is irradiated with linearly polarized light or non-polarized light to produce a photo-alignment layer.
In this specification, “linearly polarized light irradiation” is an operation for causing a photoreaction in a photo-alignment material. The wavelength of light used varies depending on the photo-alignment material used, and is not particularly limited as long as it is a wavelength necessary for the photoreaction. Preferably, the peak wavelength of light used for light irradiation is 200 nm to 700 nm, and more preferably ultraviolet light having a peak wavelength of light of 400 nm or less.

The light source used for light irradiation is a commonly used light source such as a tungsten lamp, a halogen lamp, a xenon lamp, a xenon flash lamp, a mercury lamp, a mercury xenon lamp, a carbon arc lamp, or various lasers (eg, semiconductor laser, helium). Neon laser, argon ion laser, helium cadmium laser, YAG laser), light emitting diode, cathode ray tube, and the like.

As means for obtaining linearly polarized light, a method using a polarizing plate (eg, iodine polarizing plate, dichroic dye polarizing plate, wire grid polarizing plate), reflection using a prism-based element (eg, Glan-Thompson prism) or Brewster angle A method using a type polarizer or a method using light emitted from a laser light source having polarization can be employed. Moreover, you may selectively irradiate only the light of the required wavelength using a filter, a wavelength conversion element, etc.

In the case of linearly polarized light, a method of irradiating light from the top surface or the back surface to the alignment layer surface perpendicularly or obliquely to the alignment layer is employed. The incident angle of light varies depending on the photo-alignment material, but is, for example, 0 to 90 ° (vertical), preferably 40 to 90.
When non-polarized light is used, the non-polarized light is irradiated obliquely. The incident angle is 10 to 80 °, preferably 20 to 60, particularly preferably 30 to 50 °.
The irradiation time is preferably 1 minute to 60 minutes, more preferably 1 minute to 10 minutes.

<Reflective polarizer>
The reflective polarizer includes a light reflecting layer. The reflective polarizer preferably includes two or more light reflecting layers, more preferably includes two to four layers, and more preferably includes two or three layers. The reflective polarizer preferably includes two or more light reflecting layers having different reflection center wavelengths, and more preferably includes two or three light reflecting layers having different reflection center wavelengths. The wavelength giving the peak of reflectance (that is, the reflection center wavelength) can be adjusted by changing the pitch or refractive index of the helical structure in the cholesteric liquid crystal phase of the light reflection layer formed by fixing the cholesteric liquid crystal phase. The pitch of the helical structure can be easily adjusted by changing the addition amount of the chiral agent. Specifically, Fujifilm research report No. 50 (2005) p. There is a detailed description in 60-63. Moreover, it can also adjust by conditions, such as temperature, illumination intensity, and irradiation time, when fixing a cholesteric liquid crystal phase.
The reflective polarizer preferably has a function of reflecting blue light, green light and red light.
The reflective polarizer includes a light reflecting layer that is a coating and curing layer of a polymerizable liquid crystal composition containing a discotic liquid crystal compound and a light reflecting layer that is a coating and curing layer of a polymerizable liquid crystal composition containing a rod-like liquid crystal compound. It is preferable.
Hereinafter, in a reflective polarizer including two or more light reflecting layers, a preferable combination of optical characteristics of the light reflecting layers will be exemplified.

(Example of reflective polarizer having two light reflecting layers)
Of the two light reflecting layers, any one layer is preferably a layer that also reflects light in a wavelength region exceeding the wavelength region of one color. For example, it is a layer that reflects blue light and green light in one layer, or a layer that reflects green light and red light in one layer.
Here, blue light is light having a wavelength of 380 to 499 nm, green light is light having a wavelength of 500 to 599 nm, and red light is light having a wavelength of 600 to 780 nm. Infrared light is light of 780 to 850 nm.
When a layer having a reflection half-width of 200 nm or less is controlled as a layer that also reflects light in a wavelength region exceeding the wavelength region of one color, the number of pitches is not in a single pitch but in the cholesteric spiral direction (usually in the film thickness direction). By gradually changing the pitch gradient method, a pitch gradient method capable of realizing a wide half-value width can be used. Regarding the pitch gradient method, the methods described in 1995 (Nature 378, 467-469 1995), JP-A-6-281814, and Japanese Patent No. 4990426 can be referred to. The use of the aforementioned high Δn liquid crystal compound is also preferred.

<Adhesive layer (adhesive)>
In this specification, “adhesion” is used in a concept including “adhesion”.
In the transfer material, the brightness enhancement film, and the optical sheet member described later, between the λ / 4 plate included in the reflective polarizer and the reflective polarizer, and when the reflective polarizer includes two or more light reflecting layers An adhesive layer may be included between the light reflecting layers, between the polarizing plate or polarizer and the λ / 4 plate.
As the pressure-sensitive adhesive used for the adhesive layer, for example, the ratio (tan δ = G ″ / G ′) between the storage elastic modulus G ′ and the loss elastic modulus G ″ measured by a dynamic viscoelasticity measuring device is 0.001 to 1. .5, which includes so-called pressure-sensitive adhesives and substances that are easy to creep. Examples of the pressure-sensitive adhesive include, but are not limited to, an acrylic pressure-sensitive adhesive and a polyvinyl alcohol-based adhesive.

Examples of the adhesive include a boron compound aqueous solution, an epoxy compound curable adhesive that does not contain an aromatic ring in the molecule, as disclosed in JP-A-2004-245925, and 360 described in JP-A-2008-174667. An active energy ray-curable adhesive comprising, as essential components, a photopolymerization initiator having a molar extinction coefficient of 400 or more at a wavelength of 450 nm and an ultraviolet curable compound, a (meth) acrylic adhesive described in JP-A-2008-174667 (A) (meth) acrylic compound having 2 or more (meth) acryloyl groups in the molecule in 100 parts by mass of the total amount of the compound, and (b) having a hydroxyl group in the molecule, and only having a polymerizable double bond (Meth) acrylic compound having one and (c) phenol ethylene oxide modified acrylate or nonylphenol ethylene oxide The active energy ray-curable adhesive containing a modified acrylate, and the like.

The optical sheet member described later preferably has a refractive index difference of 0.15 or less, more preferably 0.10 or less, between the reflective polarizer and the layer adjacent to the polarizing plate side of the reflective polarizer. Is particularly preferably 0.05 or less. Examples of the layer adjacent to the polarizing plate side of the reflective polarizer include the above-described adhesive layer.
Such a method for adjusting the refractive index of the adhesive layer is not particularly limited, but for example, a method described in JP-A-11-223712 can be used. Among the methods described in JP-A-11-223712, the following embodiments are particularly preferable.

Examples of the pressure-sensitive adhesive used for the adhesive layer include resins such as polyester resins, epoxy resins, polyurethane resins, silicone resins, and acrylic resins. You may use these individually or in mixture of 2 or more types. In particular, an acrylic resin is preferable because it is excellent in reliability such as water resistance, heat resistance, and light resistance, has good adhesion and transparency, and can easily adjust the refractive index to be compatible with a liquid crystal display. As the acrylic pressure-sensitive adhesive, acrylic acid and its esters, methacrylic acid and its esters, acrylamide, homopolymers of acrylic monomers such as acrylonitrile, or copolymers thereof, and at least one of the aforementioned acrylic monomers, Mention may be made of copolymers with aromatic vinyl monomers such as vinyl acetate, maleic anhydride and styrene. In particular, main monomers such as ethylene acrylate, butyl acrylate, and 2-ethylhexyl acrylate that exhibit adhesiveness, monomers such as vinyl acetate, acrylonitrile, acrylamide, styrene, methacrylate, and methyl acrylate that are cohesive components, and further improved adhesion Functional group containing methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, methylol acrylamide, glycidyl methacrylate, maleic anhydride, etc. A copolymer consisting of monomers, with a Tg (glass transition point) in the range of −60 ° C. to −15 ° C. and a weight average molecular weight in the range of 200,000 to 1 million. Shall is preferable.

As the adhesive, a sheet-like photocurable adhesive (Toagosei Group Research Annual Report 11, TREND 2011, No. 14) can be used for the adhesive layer. Like an adhesive, it is easy to bond between optical films, and is preferably crosslinked and cured with ultraviolet rays (UV) to improve storage elastic modulus, adhesive strength and heat resistance.

[Transfer Material Preparation Method]
A method for producing the transfer material is not particularly limited, but it is preferable that at least one light reflecting layer is formed by directly applying to the surface of the λ / 4 plate or the other light reflecting layer. This is because it is possible to provide a thinner brightness enhancement film by including a layer in direct contact without an adhesive layer. In addition, it is possible to provide a brightness enhancement film that is more excellent in flexibility. It is also preferable that all the light reflection layers are formed by being directly applied to the surface of the λ / 4 plate or the other light reflection layer.
The transfer material is produced by, for example, applying a polymerizable liquid crystal composition containing a liquid crystal compound to the surface of the temporary support or the alignment layer provided on the surface of the temporary support, and curing the resulting coating film to obtain λ Forming a / 4 plate.
A light reflecting layer formed on another temporary support may be laminated on the surface of the formed λ / 4 plate using an adhesive layer, and then the other temporary support may be peeled off. Note that another temporary support at this time can be the same as the temporary support in the transfer material. Alternatively, a polymerizable liquid crystal composition can be applied to the surface of the formed λ / 4 plate, and the coating film can be cured to form a light reflecting layer (first light reflecting layer). A polymerizable liquid crystal composition is further applied to the surface of the laminate of the λ / 4 plate and the first light reflection layer produced as described above, and the coating film is cured to form a light reflection layer (second light (Reflection layer) may be formed, and the light reflection layer (second light reflection layer) formed on another temporary support as described above may be laminated using an adhesive layer. In the laminated body, the third light reflection formed on the other temporary support in the order of the direct application of the third light reflection layer and the second light reflection layer from the other temporary support side. The laminate of the layer and the second light reflecting layer is laminated using the adhesive layer, and the λ / 4 plate, the first light reflecting layer, the adhesive layer, the second light reflecting layer, and the third light reflecting layer are laminated. A laminate including the layers in this order may be manufactured, and then another temporary support may be peeled off. The transfer material may be prepared by sequentially coating and curing a λ / 4 plate, a first light reflection layer, and a second light reflection layer on a temporary support. Alternatively, the λ / 4 plate, the first light reflection layer, the second light reflection layer, and the third light reflection layer may be sequentially formed on the temporary support by coating and curing. If necessary, a liquid crystal layer superposition method through an alignment layer can also be adopted.

[Brightness enhancement film]
A brightness enhancement film can be obtained by peeling the temporary support from the transfer material. In the brightness enhancement film obtained by peeling the temporary support from the transfer material, a layer formed by polymer stretching included in a general brightness enhancement film such as a PET film can be excluded. Therefore, even when pasted with a polarizing plate containing a polyvinyl alcohol film, problems such as warpage due to shrinkage are unlikely to occur.
The peeling surface obtained by peeling the temporary support from the transfer material may be a λ / 4 plate or an orientation layer, and the layer on the peeling surface is the outermost surface layer in the brightness enhancement film. When the temporary support and the λ / 4 plate are in direct contact with the transfer material, the temporary support may be peeled off at the interface between the temporary support and the λ / 4 plate. On the other hand, if the transfer material includes an alignment layer between the temporary support and the λ / 4 plate, the temporary support may be peeled off at the interface between the temporary support and the alignment layer. Peeling may be performed at the interface with the λ / 4 plate (that is, the temporary support and the alignment layer are separated from the brightness enhancement film). At this time, it is preferable to peel at the interface between the temporary support and the alignment layer.
When peeled at the interface between the temporary support and the orientation layer, and the peeled surface (outermost surface layer of the brightness enhancement film) becomes an orientation layer containing polyvinyl alcohol, the adhesion with the polarizer which is a polyvinyl alcohol film is good. It is preferable. At this time, it is preferable to use a polyvinyl alcohol-based adhesive as the adhesive.

When the brightness enhancement film is incorporated in a liquid crystal display device, the brightness enhancement film improves the brightness of the liquid crystal display device by the following mechanism.
The light reflecting layer formed by fixing the cholesteric liquid crystal phase contained in the reflective polarizer in the brightness enhancement film has at least one of right circularly polarized light and left circularly polarized light (circularly polarized light in the first polarization state) having a reflection center wavelength. Reflects in the nearby wavelength band and transmits the other (circularly polarized light in the second polarization state). The reflected circularly polarized light in the second polarization state is randomized in its direction and polarization state by a reflection member (also referred to as a light guide or an optical resonator), which will be described later, and is recycled. Again, part of the light is reflected as circularly polarized light in the first polarization state and the remaining part is transmitted as circularly polarized light in the second polarization state, thereby increasing the light utilization rate on the backlight side and increasing the brightness of the liquid crystal display device. Can be improved.
The light emitted from the reflective polarizer, that is, the polarization state of the transmitted light and the reflected light of the reflective polarizer can be measured, for example, by measuring the polarization with an Axoscan from Axometrics.

[Method for Manufacturing Optical Sheet Member]
In this specification, an optical sheet member means a member including a brightness enhancement film and a polarizing plate including a polarizer.
The optical sheet member can be produced by a method including peeling the temporary support of the transfer material and bonding the release surface obtained by peeling to the polarizing plate with an adhesive. When bonding, the angle formed between the slow axis of the λ / 4 plate and the absorption axis of the polarizer may be 30 to 60 °. By doing in this way, it can laminate | stack so that the direction of the linearly polarized light which permeate | transmitted (lambda) / 4 board used for a brightness improvement film may become in parallel with the transmission-axis direction of a polarizing plate.
The angle formed by the slow axis of the λ / 4 plate and the absorption axis of the polarizer is preferably 35 to 55 °, more preferably 40 to 50 °, and even more preferably 45 °. Bonding may be performed with an adhesive, for example.
In order to avoid adhesion of dust or the like to the release surface, it is preferable that the polarizing plate is bonded immediately after the temporary support of the transfer material is released.

FIG. 2 shows a schematic diagram of the optical sheet member. The optical sheet member 21 includes the brightness enhancement film 11 and the polarizing plate 1 including the polarizer 3. In use, a backlight is placed at the bottom of the figure. The polarizing plate 1 and the brightness enhancement film 11 may be laminated via the adhesive layer 20. The polarizing plate is preferably a backlight side polarizing plate when incorporated in a liquid crystal display device.
At the time of lamination, the polarizing plate and the brightness enhancement film are preferably bonded by roll-to-roll using an adhesive. When bonding by roll-to-roll, the brightness enhancement film may be directly bonded to the polarizer without using the polarizer protective film on the backlight unit side of the polarizing plate.
The film thickness of the optical sheet member may be 13 μm to 150 μm, and preferably 15 μm to 100 μm.

<Polarizing plate>
The polarizing plate may be composed only of a polarizer. Usually, like the polarizing plate used in a liquid crystal display device, the polarizing plate and two polarizing plate protective films (hereinafter referred to as protection) disposed on both sides thereof are used. (Also referred to as a film). Of the two protective films, a retardation film is also preferably used as the protective film disposed on the liquid crystal cell side. The polarizing plate of the optical sheet member may be composed of a polarizer and a single polarizing plate protective film.
In FIG. 2, the polarizing plate 1 includes a polarizer 3. The polarizing plate 1 preferably includes a polarizing plate protective film 2 that may be a retardation film on the surface of the polarizer 3 on the viewing side. The polarizing plate 1 may include the polarizing plate protective film 4 on the surface of the polarizer 3 on the backlight unit 31 side (FIGS. 1B and 1D), but may not include ( FIG. 1 (a) and (c)).

(Polarizer)
As the polarizer, it is preferable to use a polymer film in which iodine is adsorbed and oriented. The polymer film is not particularly limited, and various types can be used. For example, polyvinyl alcohol films, polyethylene terephthalate films, ethylene / vinyl acetate copolymer films, partially saponified films of these, hydrophilic polymer films such as cellulose films, polyvinyl alcohol dehydrated products and polychlorinated Examples include polyene-based oriented films such as vinyl dehydrochlorinated products. Among these, it is preferable to use a polyvinyl alcohol film excellent in dyeability with iodine as a polarizer.

Polyvinyl alcohol or a derivative thereof is used as the material for the polyvinyl alcohol film. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters thereof, acrylamide and the like. Can be mentioned.

The polymerization degree of the polymer that is the material of the polymer film is generally 500 to 10,000, preferably in the range of 1000 to 6000, and more preferably in the range of 1400 to 4000. Furthermore, in the case of a saponified film, the degree of saponification is preferably 75 mol% or more, more preferably 98 mol% or more, for example, from the viewpoint of solubility in water, and more preferably 98.3 to 99.8 mol. % Is more preferable.

The aforementioned polymer film (unstretched film) is at least subjected to uniaxial stretching treatment and iodine dyeing treatment according to a conventional method. Furthermore, boric acid treatment and washing treatment can be performed. Further, the polymer film (stretched film) subjected to the above-described treatment is dried according to a conventional method to become a polarizer.
The thickness of the polarizer is not particularly limited, and is usually 5 to 80 μm, preferably 5 to 50 μm, more preferably 5 to 25 μm.

As the optical characteristics of the polarizer, the single transmittance when measured with a single polarizer is preferably 43% or more, and more preferably in the range of 43.3 to 45.0%. Further, it is preferable that the orthogonal transmittance measured by superposing two polarizers described above so that the absorption axes of the two polarizers are 90 ° with each other is smaller, and practically 0.00 % Or more and 0.050% or less is preferable, and 0.030% or less is more preferable. The degree of polarization is preferably 99.90% or more and 100% or less for practical use, and particularly preferably 99.93% or more and 100% or less. Even when measured as a polarizing plate, it is preferable to obtain optical characteristics substantially equivalent to this.

(Polarizing plate protective film)
The optical sheet member may or may not have a polarizing plate protective film on the side opposite to the liquid crystal cell of the polarizer. When a polarizing plate protective film is not provided on the side opposite to the liquid crystal cell of the polarizer, a reflective polarizer described later may be provided directly or via an adhesive.
Among the protective films described above, as the protective film disposed on the side opposite to the liquid crystal cell, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropyl cellulose, dipropyl cellulose, and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetylcellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “ UZ-TAC ”and“ KC Series ”manufactured by Konica.

A specific example of the cyclic polyolefin resin is preferably a norbornene resin. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include cyclic olefin ring-opening (co) polymers, cyclic olefin addition polymers, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And the graft polymer which modified these with unsaturated carboxylic acid or its derivative (s), and those hydrides, etc. are mentioned. Specific examples of the cyclic olefin include norbornene monomers.

Various products are commercially available as cyclic polyolefin resins. Specific examples include the product names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, the product name “ARTON” manufactured by JSR Corporation, the product name “TOPAS” manufactured by TICONA, and the product rules manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

Any appropriate (meth) acrylic resin can be adopted as the (meth) acrylic resin. For example, poly (meth) acrylate such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymers, (meth) methyl acrylate-styrene copolymers (MS resin, etc.), polymers having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, And methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferable examples include C1-6 alkyl poly (meth) acrylates such as poly (meth) acrylate methyl. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by mass, preferably 70 to 100% by mass).

Specific examples of the (meth) acrylic resin include, for example, (Meth) acrylic resin having a ring structure in the molecule described in Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

(Meth) acrylic resin having a lactone ring structure can also be used as the (meth) acrylic resin. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

The thickness of the protective film can be set as appropriate, but is generally about 1 to 80 μm from the viewpoints of strength, workability such as handling, and thin layer properties. In particular, 1 to 60 μm is preferable, and 5 to 40 μm is more preferable. The protective film is particularly suitable for a thickness of 5 to 25 μm.

[Liquid Crystal Display]
The optical sheet member can be used in a liquid crystal display device. The brightness enhancement film can be used in a liquid crystal display device in combination with a polarizing plate.
The liquid crystal display device is an optical sheet member or a brightness enhancement film and a polarizing plate,
Blue light having an emission center wavelength in a wavelength band of 430 to 480 nm;
Green light having an emission center wavelength in a wavelength band of 500 to 600 nm,
A backlight unit including a light source that emits red light having at least a part of a peak of emission intensity in a wavelength band of 600 to 700 nm;
The backlight unit includes a reflection member that converts and reflects the polarization state of light emitted from the light source and reflected by the brightness enhancement film or the optical sheet member at the rear of the light source. It is preferable.

<Backlight unit>
The configuration of the backlight unit may be an edge light method using a light guide plate or a reflection plate as a constituent member, or a direct type.
In the liquid crystal display device, the above-described backlight unit includes a reflection member at the rear portion of the light source that converts and reflects the polarization state of light emitted from the light source and reflected by the brightness enhancement film or the above-described optical sheet member. There is no restriction | limiting in particular as such a reflecting member, A well-known thing can be used, and it is described in patent 3416302, patent 3363565, patent 4091978, patent 3448626, etc., The content of these gazettes is this Incorporated into the invention.
An example of the light source of the backlight unit is a white light source such as a white LED (Light Emitting Diode). As another example, a light source having a blue light-emitting diode that emits blue light and a fluorescent material that emits green light and red light when blue light from the blue light-emitting diode is incident, emits light in a wavelength band of 300 nm to less than 430 nm. A light source having a UV light emitting diode that emits UV light having a central wavelength, and a fluorescent material that emits blue light, green light, and red light when the UV light of the UV light emitting diode is incident, and blue light that emits the blue light described above Emits blue light such as a light source (pseudo white LED) having a light emitting diode and a fluorescent material (such as a yellow phosphor) that emits a broad peak of light from the green light to the red light when the blue light is incident. Examples include a blue light emitting diode, a green light emitting diode that emits green light, and a red light emitting diode that emits red light.
Among these, white LEDs and blue light emitting diodes emitting blue light from the viewpoint of energy conversion (power-light conversion efficiency) and the aforementioned green light and red light described above when blue light from the blue light emitting diode is incident. A light source having a fluorescent material that emits light, or a blue light emitting diode that emits blue light, and a fluorescent material that emits a broad peak of light from the green light to the red light when the blue light is incident (yellow fluorescent light) It is more preferable that the light source of the backlight unit is a white LED or a blue light emitting diode that emits blue light and a blue light emitting diode. It is more preferable to have a fluorescent material that emits the aforementioned green light and the aforementioned red light when blue light is incident. In a more preferred embodiment, the backlight unit has a blue light having an emission center wavelength in the wavelength band of 430 to 480 nm, a green light having an emission center wavelength in the wavelength band of 500 to 600 nm, and a wavelength band of 600 to 700 nm. It is preferable to emit red light having at least part of the peak of emission intensity.

Examples of fluorescent materials include yttrium / aluminum / garnet yellow phosphors and terbium / aluminum / garnet yellow phosphors. The fluorescence wavelength of the fluorescent material can be controlled by changing the particle diameter of the phosphor.
In the liquid crystal display device, the blue light-emitting diode that emits the blue light and the fluorescent material that emits the green light and the red light when the blue light of the blue light-emitting diode is incident are quantum dots. It is a member (for example, a quantum dot sheet or a bar-shaped quantum dot bar), and the quantum dot member is preferably disposed between the optical sheet member and the blue light source. Such a quantum dot member is not particularly limited, and a known member can be used. For example, JP 2012-169271 A, SID '12 DIGEST p. 895, etc., and the contents of these documents are incorporated in the present invention. As such a quantum dot sheet, QDEF (Quantum Dot Enhancement Film, manufactured by Nanosys) can be used.

It is preferable that the emission center wavelength of blue light emitted from the backlight unit is in the wavelength band of 440 to 470 nm.
The emission center wavelength of the green light emitted from the backlight unit is preferably in the wavelength band of 520 to 570 nm.
It is preferable that the emission center wavelength of red light emitted from the backlight unit is in a wavelength band of 600 to 640 nm.

It is preferable that the full width at half maximum of the blue light, the green light, and the red light is 100 nm or less.
The blue light emitted from the backlight unit preferably has an emission intensity peak with a half-value width of 80 nm or less, more preferably an emission intensity peak with a half-value width of 70 nm or less, and a half-value width of 30 nm or less. It is particularly preferable to have a peak of emission intensity as follows.
The green light emitted from the backlight unit preferably has an emission intensity peak with a half-value width of 80 nm or less, more preferably an emission intensity peak with a half-value width of 70 nm or less, and a half-value width of 60 nm or less. It is particularly preferable to have a peak of emission intensity as follows.
The red light emitted from the backlight unit preferably has an emission intensity peak with a half-value width of 80 nm or less, more preferably an emission intensity peak with a half-value width of 70 nm or less, and a half-value width of 60 nm or less. It is particularly preferable to have a peak of emission intensity as follows.

In addition, the backlight unit preferably includes a known diffusion plate, diffusion sheet, prism sheet (for example, BEF), and a light guide. Other members are also described in Japanese Patent No. 3416302, Japanese Patent No. 3363565, Japanese Patent No. 4091978, Japanese Patent No. 3448626, and the contents of these publications are incorporated in the present invention.
In order to further improve the front luminance of the liquid crystal display device using the brightness enhancement film and the optical sheet member of the present invention, it is preferable to provide the backlight unit with two prism sheets. Moreover, it is preferable that the directions of the prisms of the two prism sheets are substantially parallel. The direction in which the prisms of the two prism sheets are substantially parallel means that the angle formed by the prisms of the two prism sheets is within ± 5 °. Note that the prism sheet has a plurality of protrusions (in the present specification, these protrusions are also referred to as prisms) extending in one direction within the surface of the prism sheet. The directions in which the plurality of prisms arranged in are extended are parallel. The direction of the prism refers to the extending direction of a plurality of prisms arranged in a row.

<Display panel>
An example of a preferable display panel of the above-described liquid crystal display device is a transmissive mode liquid crystal panel, which includes a pair of polarizers and a liquid crystal cell therebetween. A retardation film for viewing angle compensation is usually disposed between each polarizer and the liquid crystal cell. There is no restriction | limiting in particular about the structure of a liquid crystal cell, The liquid crystal cell of a general structure is employable. The liquid crystal cell includes, for example, a pair of substrates arranged opposite to each other and a liquid crystal layer sandwiched between the pair of substrates, and may include a color filter layer, if necessary. The driving mode of the liquid crystal cell is not particularly limited, and is twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optically compensated bend cell (OCB). Various modes such as can be used.

One embodiment of a liquid crystal display device has a liquid crystal cell in which a liquid crystal layer is sandwiched between substrates provided with electrodes on at least one opposite side, and the liquid crystal cell is arranged between two polarizing plates. preferable. The liquid crystal display device includes a liquid crystal cell in which liquid crystal is sealed between upper and lower substrates, and displays an image by changing the alignment state of the liquid crystal by applying a voltage. Furthermore, it has an accompanying functional layer such as a polarizing plate protective film, an optical compensation member that performs optical compensation, and an adhesive layer as necessary. The liquid crystal display device may include other members. For example, along with (or instead of) a color filter substrate, thin layer transistor substrate, lens film, diffusion sheet, hard coat layer, antireflection layer, low reflection layer, antiglare layer, etc., forward scattering layer, primer layer, antistatic layer Further, a surface layer such as an undercoat layer may be disposed.

<Method of bonding optical sheet member to liquid crystal display device>
As a method for bonding the brightness enhancement film or the optical sheet member to the liquid crystal display device, a known method can be used. In addition, a roll-to-panel manufacturing method can be used, which is preferable for improving productivity and yield. The roll-to-panel manufacturing method is described in JP-A-2011-48381, JP-A-2009-175653, JP-A-4628488, JP-B-4729647, WO2012 / 014602, WO2012 / 014571, and the like. It is not limited.

Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Preparation of support HSA with alignment film>
(Alkaline saponification treatment)
A cellulose acylate film “TD80UL” (manufactured by Fuji Film Co., Ltd.) was passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C. Thereafter, an alkali solution having the composition shown below was applied to one side of the film using a bar coater at a coating amount of 14 ml / m ² and heated to 110 ° C. The heated film was transported for 10 seconds under a steam far-infrared heater manufactured by Noritake Company Limited. Subsequently, 3 ml / m ^{2 of} pure water was applied using the same bar coater. Further, washing with a fountain coater and draining with an air knife were repeated three times, and then the film was transported to a drying zone at 70 ° C. for 10 seconds and dried to produce an alkali saponified film.

──────────────────────────────────
Alkaline solution composition ──────────────────────────────────
Potassium hydroxide 4.7 parts by weight Water 15.8 parts by weight Isopropanol 63.7 parts by weight Surfactant SF-1: C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₂₀ H 1.0 part by weight Propylene glycol 14. 8 parts by mass ──────────────────────────────────

(Formation of alignment film)
An alignment film coating solution having the following composition was continuously applied to the long support A saponified as described above with a # 14 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 100 ° C. for 120 seconds. The obtained coating film was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle formed by the longitudinal direction of the film and the rotation axis of the rubbing roller was about 45 °.
──────────────────────────────────
Composition of alignment film coating solution ──────────────────────────────────
Denatured polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight Photopolymerization initiator (Irgacure 2959, manufactured by BASF) 0.3 parts by weight ───────── ─────────────────────────

<Preparation of support HSB with alignment film>
The surface of the cellulose acylate film “TD80UL” (manufactured by FUJIFILM Corporation) was removed using a roll having low foreign matter and adhesive strength. Thereafter, an alignment film coating solution having the following composition was continuously applied with a # 16 wire bar. Further, it was dried with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. The obtained coating film was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle formed by the longitudinal direction of the film and the rotation axis of the rubbing roller was about 45 °.

──────────────────────────────────
Composition of alignment film coating solution ──────────────────────────────────
Denatured polyvinyl alcohol 10 parts by weight Water 380 parts by weight Methanol 120 parts by weight Glutaraldehyde 0.5 parts by weight Photopolymerization initiator (Irgacure 2959, manufactured by BASF) 0.2 parts by weight ───────── ─────────────────────────

<Preparation of support HSC>
The PET film (Cosmo Shine manufactured by Toyobo Co., Ltd.) was directly and continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the rotation axis of the rubbing roller was 45 ° clockwise relative to the longitudinal direction of the film.

<Formation of λ / 4 plate using A1 discotic liquid crystal compound>
A coating liquid A1 containing a discotic liquid crystal compound having the following composition is continuously applied to the surface of the alignment film of the support HSA or the support HSB or the rubbing surface of the support HSC (see Table 1) with a wire bar # 3.6. Applied. The conveyance speed (V) of the film was 20 m / min. In order to dry the solvent of the coating solution and to mature the alignment of the discotic liquid crystal compound, it was heated with warm air at 130 ° C. for 90 seconds. Subsequently, UV irradiation was performed at 80 ° C. to fix the orientation of the liquid crystal compound and form an optically anisotropic layer.
At this time, the UV irradiation amount was 300 mJ / cm ² .
──────────────────────────────────
Coating liquid A1 containing discotic liquid crystal compound
――――――――――――――――――――――――――――――――――
Discotic liquid crystal compound (Compound 101) 80 parts by mass Discotic liquid crystal compound (Compound 102) 20 parts by mass Alignment aid 1 0.9 parts by mass Alignment aid 2 0.1 parts by mass Surfactant 1 0.3 parts by mass polymerization Initiator 1 3 parts by weight Methyl ethyl ketone 301 parts by weight ──────────────────────────────────

The alignment aids 1 and 2 are each a mixture of two types of compounds having different methyl group substitution positions on the trimethyl-substituted benzene ring (mixing ratio of the two types of compounds 50:50 (mass ratio)). In addition, the description “a / b = 98/2” of the surfactant 1 indicates that a is 98 mass% and b is 2 mass%.

<A2 Formation of λ / 4 plate using rod-like liquid crystal compound>
A coating liquid C1 containing a rod-shaped liquid crystal compound having the following composition was continuously applied to the prepared alignment film with a # 3.6 wire bar. The conveyance speed (V) of the film was 20 m / min. In order to dry the solvent of the coating solution and to mature the alignment of the rod-like liquid crystal compound, it was heated with hot air at 85 ° C. for 120 seconds. Subsequently, UV irradiation was performed at 80 ° C. to fix the orientation of the liquid crystal compound and form an optically anisotropic layer.
At this time, the UV irradiation amount was 300 mJ / cm ² .
――――――――――――――――――――――――――――――――――
Coating liquid A2 containing rod-like liquid crystal compound
――――――――――――――――――――――――――――――――――
Rod-like liquid crystal compound 201 83 parts by weight Rod-like liquid crystal compound 202 14 parts by weight Rod-like liquid crystal compound 203 3 parts by weight polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by weight polymerization initiator IRGACURE819 (manufactured by BASF) 4 parts by weight surfactant 2 0.05 parts by weight surfactant 3 0.01 parts by weight methyl ethyl ketone 157 parts by weight cyclohexanone 8 parts by weight ――――――――――――――――――――― ―――――――――――――

<Formation of λ / 4 plate made of stretched film>
Preparation of cellulose acylate solution:
The main agent, additive and solvent described below are put into a mixing tank, stirred to dissolve each component, heated to 90 ° C. for about 10 minutes, and then filtered with an average pore size of 34 μm and sintered with an average pore size of 10 μm. It filtered with the metal filter.
――――――――――――――――――――――――――――――――――
Dope composition ――――――――――――――――――――――――――――――――――
-348 parts by mass of methylene chloride-52 parts by mass of methanol-100 parts by mass of cellulose acetate with a substitution degree of 2.43-Inorganic fine particles (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.)
0.2 parts by mass ――――――――――――――――――――――――――――――――――

Casting:
The above-mentioned dope was cast using a band casting machine so as to be 100 μm after drying. The band was made of stainless steel.
Dry:
The web (film) obtained by casting was peeled from the band, and then the pass roll was conveyed and dried at a drying temperature of 120 ° C. for 20 minutes. In addition, the drying temperature here means the film surface temperature of a film.
Stretch:
The obtained web (film) is peeled from the band, sandwiched between clips, and is 2.3 times in the film transport direction (MD) using a tenter at a stretching temperature of 230 ° C. and a stretching ratio under the conditions of free end uniaxial stretching. So that it was stretched.
The obtained film was evaluated, and it was confirmed that an A plate with a film thickness of 45 μm and Re = 135 nm could be produced.

<B1 Formation of Cholesteric Layer Using Discotic Liquid Crystal Compound>
As a light reflecting layer formed by fixing a cholesteric liquid crystal phase using a discotic liquid crystal compound as a liquid crystal compound on the surface of any one of the λ / 4 plates (see Table 1) prepared by the above method, One light reflecting layer was formed.
A coating liquid B1 containing a discotic liquid crystal compound having the following composition was adjusted on the surface of the prepared alignment film so as to have the film thickness shown in Table 1 and continuously applied.
Subsequently, the solvent was dried at 70 ° C. for 2 minutes, and after evaporating the solvent, heat aging was performed at 115 ° C. for 3 minutes to obtain a uniform alignment state.
A light reflection layer was formed by irradiating with ultraviolet rays using a mercury lamp.
At this time, the UV irradiation amount was 300 mJ / cm ² .
──────────────────────────────────
Composition of optically anisotropic layer coating solution B1 ――――――――――――――――――――――――――――――――――
Discotic liquid crystal compound (Compound 101) 80 parts by mass Discotic liquid crystal compound (Compound 102) 20 parts by mass of polymerizable monomer 10 parts by mass Surfactant 1 0.3 part by mass Polymerization initiator 1 3 parts by mass chiral agent 1 Table 1 Methyl ethyl ketone 290 parts by mass Cyclohexanone 50 parts by mass ―――――――――――――――――――――――――――――――――

<B2 Formation of Cholesteric Layer Using Rod-shaped Liquid Crystal Compound>
Fujifilm PET (thickness: 75 μm) was prepared as a temporary support and continuously rubbed. The rubbing treatment direction was parallel to the film longitudinal direction. In addition, it confirmed that a general PET film (For example, Cosmo Shine A4100 (Toyobo)) can be used as a temporary support body other than the said PET film.
A coating liquid B2 containing a rod-like liquid crystal compound having the following composition was adjusted so as to have the film thickness shown in Table 1 on the rubbing treated surface of the PET film and continuously applied. The conveyance speed (V) of the film was 20 m / min. In order to dry the solvent of the coating solution and to mature the alignment of the rod-like liquid crystal compound, it was heated with hot air at 85 ° C. for 120 seconds. Subsequently, UV irradiation was performed at 80 ° C. to fix the orientation of the liquid crystal compound and form a light reflection layer.
At this time, the UV irradiation amount was 300 mJ / cm ² .
――――――――――――――――――――――――――――――――――
Coating liquid B2 containing a rod-like liquid crystal compound
――――――――――――――――――――――――――――――――――
Rod-like liquid crystal compound 201 83 parts by weight Rod-like liquid crystal compound 202 15 parts by weight Rod-like liquid crystal compound 203 2 parts by weight polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by weight polymerization initiator IRGACURE 819 (manufactured by BASF) 4 parts by weight surfactant 2 0.05 parts by weight surfactant 3 0.01 parts by weight chiral agent LC756 (manufactured by BASF) Methyl ethyl ketone described in Table 1 165 parts by weight cyclohexanone 10 parts by weight ――――――――― ―――――――――――――――――――――――――

<B3 Formation of Cholesteric Layer Using High Δn Rod-shaped Liquid Crystal Compound>
Fujifilm PET (thickness: 75 μm) was prepared as a temporary support and continuously rubbed. The rubbing treatment direction was parallel to the film longitudinal direction. In addition to the above PET film, it was confirmed that a general PET film (for example, Cosmo Shine A4100 (Toyobo)) could be used as a temporary support. The coating liquid B3 containing a rod-like liquid crystal compound having the following composition was used as the above PET film. It adjusted so that it might become the film thickness as described in Table 1 on the rubbing process surface of the film, and it apply | coated continuously. The conveyance speed (V) of the film was 20 m / min. In order to dry the solvent of the coating solution and to mature the alignment of the rod-like liquid crystal compound, it was heated with hot air at 85 ° C. for 120 seconds. Subsequently, UV irradiation was performed at 80 ° C. to fix the orientation of the liquid crystal compound and form a light reflection layer.
At this time, the UV irradiation amount was 300 mJ / cm ² .
――――――――――――――――――――――――――――――――――
Coating liquid B3 containing a rod-like liquid crystal compound
――――――――――――――――――――――――――――――――――
Rod-shaped liquid crystal compound 204 100 parts by mass polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by mass polymerization initiator IRGACURE819 (manufactured by BASF) 4 parts by mass surfactant 2 0.05 parts by mass surfactant Agent 3 0.01 parts by mass chiral agent LC756 (manufactured by BASF) Methyl ethyl ketone 200 parts by mass Cyclohexanone 20 parts by mass in Table 1 ------- ―――――――――――

<Formation of pitch gradient cholesteric layer using B4 high Δn rod-like liquid crystal compound>
Fujifilm PET (thickness: 75 μm) was prepared as a temporary support and continuously rubbed. The rubbing treatment direction was parallel to the film longitudinal direction. In addition, it confirmed that a general PET film (For example, Cosmo Shine A4100 (Toyobo)) can be used as a temporary support body other than the said PET film.
Coating liquid B4 containing a rod-like liquid crystal compound having the following composition was adjusted to the film thickness shown in Table 1 on the rubbing-treated surface of the PET film and continuously applied. The conveyance speed (V) of the film was 20 m / min.

In order to dry the solvent of the coating solution and to mature the alignment of the rod-like liquid crystal compound, it was heated with a warm air of 110 ° C. for 120 seconds.
Subsequently, UV irradiation was performed at 100 ° C. with an irradiation amount of 20 mJ / cm ² .
Thereafter, as orientation ripening, heating was performed with warm air at 80 ° C. for 120 seconds.
Subsequently, UV irradiation was performed at 70 ° C. with an irradiation amount of 350 mJ / cm ² to form a light reflection layer.
――――――――――――――――――――――――――――――――――
Coating liquid B4 containing a rod-like liquid crystal compound
――――――――――――――――――――――――――――――――――
Rod-shaped liquid crystal compound 204 100 parts by mass polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by mass polymerization initiator 1 4 parts by mass surfactant 2 0.05 part by mass surfactant 3 0.01 Mass part chiral agent 2 Methyl ethyl ketone listed in Table 1 200 parts by mass Cyclohexanone 20 parts by mass ――――――――――――――――――――――――――――――――― -

<Formation of brightness enhancement film>
The films prepared above were laminated in the order shown in Table 1.
About what was described as "Yes" about the adhesive layer in Table 1, the layers described on both sides of the adhesive layer were bonded using an adhesive (SK2057 manufactured by Soken Chemical Co., Ltd.). About what was formed including bonding using the light reflection layer formed in the temporary support body surface, the temporary support body peeled after bonding. Peeling was performed at the interface between the temporary support and the layer in direct contact with the temporary support in the film. That is, the film having an alignment layer between the temporary support and the λ / 4 plate was peeled between the temporary support and the alignment layer.

<Preparation of optical sheet member>
Next, a polarizer is produced in the same manner as in [0219] to [0220] of JP-A-2006-293275, and the brightness enhancement film and the polarizing plate protective film (TD40UL (manufactured by FUJIFILM Corporation) are used as the polarizer. The optical sheet member was manufactured by pasting to both sides of each.
At the time of bonding, the support of the brightness enhancement film was peeled off, and the peeled surface was bonded to a polarizer with the adhesive described in Table 1. In the example described as “Adhesive” in Table 1, it was bonded with SK2057 manufactured by Soken Chemical. In the example of “PVA glue”, the laminated film is bonded to PVA using a polyvinyl alcohol adhesive (PVA (manufactured by Kuraray Co., Ltd., PVA-117H) 3% aqueous solution as an adhesive). And dried at 100 ° C. for 2 minutes to cure. In the example described as “UV adhesive”, a commercially available epoxy UV curable resin (UV curable adhesive NOA72 manufactured by NORLAND) was applied in a thickness of 2 μm, and the laminated film was bonded to PVA. Later, it was cured with ultraviolet light.

<Manufacture of liquid crystal display devices>
A commercially available liquid crystal display device (manufactured by Panasonic, trade name TH-L42D2) was disassembled, the backlight side polarizing plate was changed to the optical sheet member prepared above, and the backlight unit was replaced with the following quantum dots (RGB narrow band) It changed into the backlight unit, the liquid crystal display device was manufactured, and it used for the following evaluation.
The used quantum dot backlight unit includes a blue light emitting diode (Nichia B-LED, main wavelength 465 nm, half-value width 20 nm) as a light source. In addition, a quantum dot member that emits fluorescence of green light having a center wavelength of 535 nm and a half-value width of 40 nm and red light having a center wavelength of 630 nm and a half-value width of 40 nm when blue light of the blue light-emitting diode is incident on the front portion of the light source is provided. . In addition, a reflection member that converts and reflects the polarization state of light emitted from the light source and reflected by the above-described brightness enhancement film or the above-described optical sheet member is provided behind the light source.
The evaluation results are shown in Table 2.

(1) Front luminance The front luminance of the liquid crystal display device is measured using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM) in the same manner as in the method described in [0180] of JP-A-2009-93166. The front luminance of was measured. Based on the results, evaluation was made according to the following criteria. Evaluation was made on the basis of Comparative Example 6 in which no brightness enhancement film was provided.
5: When the front luminance of the liquid crystal display device of Comparative Example 6 is 100%, it is 130% or more, which is good.
4: When the front luminance of the liquid crystal display device of Comparative Example 6 is 100%, it is 120% to less than 130%, which is relatively good.
3: When the front luminance of the liquid crystal display device of Comparative Example 6 is 100%, it is 110% to less than 120%, which is relatively bad.
2: When the front luminance of the liquid crystal display device of Comparative Example 6 is 100%, it is less than 110%, which is bad.

(2) Diagonal tint change Diagonal tint change Δu′v ′ of the liquid crystal display device was evaluated by the following method. The hue color difference Δu′v ′ obtained by calculating the difference between the color coordinates u ′ and v ′ between the front (polar angle 0 degree) and the polar angle 60 degrees direction is measured in the azimuth angle 0 to 360 degrees direction, and the average The value was used as an evaluation index of the diagonal color change Δu′v ′. A measuring machine (EZ-Contrast 160D, manufactured by ELDIM) was used for measuring the color coordinates u′v ′. Based on the results, evaluation was made according to the following criteria.
5: When the oblique color change of the liquid crystal display device of Comparative Example 7 is 100%, the color change is less than 60%.
4: When the oblique color change of the liquid crystal display device of Comparative Example 7 is 100%, the color change is 60% or more to less than 70%.
3: When the oblique color change of the liquid crystal display device of Comparative Example 7 is 100%, the color change is 70% to less than 80%.
2: When the oblique color change of the liquid crystal display device of Comparative Example 7 is 100%, the color change is 80% or more to 100%.

Panel warpage: Bending The polarizing plate on the lower side of an IPS mode liquid crystal cell (LGLS 42LS5600) was peeled off, and the produced polarizing plate with a brightness enhancement film was attached to the liquid crystal cell. At this time, the transmission axis of the polarizing plate was arranged so as to be crossed Nicol similarly to the original product.
The panel warpage at the time of humidity change of the liquid crystal display device produced as described above was evaluated by the following method.
(Panel warping after elapse of high temperature and high humidity environment) After allowing the liquid crystal display device to pass for 48 hours at 60 ° C. and 90% relative humidity, the liquid crystal display device was disassembled in an environment of 25 ° C. and 60% relative humidity to obtain a liquid crystal cell The amount of warpage was measured as panel warpage.
5: Panel warpage is less than 7 mm and warpage is small 4: Panel warpage is 7 mm or more and less than 8 mm and warpage is relatively small 3: Panel warpage is 8 mm or more and less than 9 mm and warpage is relatively large 2 : Large warpage when panel warpage is 9mm or more

Surface scratch resistance After peeling off the support, it was bonded to a polarizer, and then the surface opposite to the brightness enhancement film was bonded to the glass substrate with an adhesive.
The deformation after the following load was applied to this sample was measured with a non-contact surface / layer cross-sectional shape measurement system VertScan (manufactured by Ryoka System).
As for the load, the tip of the push-pull gauge was processed into a spherical shape of 5 mmφ, and a load of 0.5 kg was applied for 10 seconds.
4: Deformation amount is 3 μm or less and is not substantially visible 3; Deformation amount is 3 μm or more and is visually recognized

101 Temporary support 112 Alignment layer 1 Polarizing plate 2 Polarizing plate protective film (retardation film)
3 Polarizer 4 Polarizing Plate Protective Film 11 Brightness Improvement Film 12 λ / 4 Plate 14a First Light Reflecting Layer 14b Second Light Reflecting Layer 14c Third Light Reflecting Layer 20 Adhesive Layer (Adhesive)
21 Optical sheet member

Claims (20)

1. A transfer material for a brightness enhancement film,
   The brightness enhancement film has a thickness of 4 μm or more and 30 μm or less,
   The transfer material includes a detachable temporary support, a λ / 4 plate, and a reflective polarizer in this order,
   The reflective polarizer includes a light reflecting layer formed by fixing a cholesteric liquid crystal phase,
   The λ / 4 plate and the light reflection layer are both transfer materials which are coating and curing layers of a polymerizable liquid crystal composition containing a liquid crystal compound.
2. The reflective polarizer comprises at least two light reflective layers;
   The transfer material according to claim 1, wherein at least two adjacent layers selected from the group consisting of at least two light reflecting layers and the λ / 4 plate are in direct contact with each other.
3. The transfer material according to claim 2, wherein one layer of the light reflecting layer is in direct contact with the λ / 4 plate.
4. The transfer material according to any one of claims 1 to 3, wherein the film thickness of the brightness enhancement film is 15 袖 m or less.
5. The transfer material according to any one of claims 1 to 4, wherein the temporary support is selected from the group consisting of a cellulose acylate film and a polyester film.
6. Including an alignment layer;
   The transfer material according to any one of claims 1 to 5, comprising the temporary support, the alignment layer, the λ / 4 plate, and the reflective polarizer in this order.
7. The transfer material according to claim 6, wherein the temporary support and the alignment layer are in direct contact, and the alignment layer contains polyvinyl alcohol.
8. The transfer material according to claim 7, wherein the temporary support is an unsaponified cellulose acylate film.
9. The reflective polarizer includes a coating / curing layer of a polymerizable liquid crystal composition containing a discotic liquid crystal compound and a coating / curing layer of a polymerizable liquid crystal composition containing a rod-shaped liquid crystal compound. The transfer material described.
10. The transfer material according to any one of claims 1 to 9, wherein Δn of the rod-like liquid crystal compound is 0.2 or more.
11. The transfer according to any one of claims 1 to 10, wherein the helical pitch of the cholesteric liquid crystal phase with the coating and hardening layer of the polymerizable liquid crystal composition containing the rod-like liquid crystal compound is continuously changed in the film thickness direction of the layer. material.
12. A method for producing a transfer material according to any one of claims 1 to 11,
    The λ / 4 plate is formed by applying a polymerizable liquid crystal composition containing a liquid crystal compound to the surface of the temporary support or the alignment layer provided on the surface of the temporary support, and curing the resulting coating film. Manufacturing method.
13. The manufacturing method according to claim 12, comprising forming the light reflecting layer by curing a coating film obtained by coating a polymerizable liquid crystal composition containing a liquid crystal compound on the surface of the λ / 4 plate.
14. A brightness enhancement film obtained by peeling the temporary support from the transfer material according to any one of claims 1 to 5, comprising the λ / 4 plate and the reflective polarizer, and having an outermost surface. A brightness enhancement film which is the λ / 4 plate.
15. A brightness enhancement film obtained by peeling the temporary support from the transfer material according to claim 7 or 8, comprising the alignment layer, the λ / 4 plate, and the reflective polarizer in this order. A brightness enhancement film whose surface is the alignment layer.
16. Peeling off the temporary support of the transfer material according to any one of claims 1 to 11,
    The manufacturing method of the optical sheet member including bonding the peeling surface obtained by the said peeling to the polarizing plate containing a polarizer with an adhesive agent.
17. The manufacturing method according to claim 16, wherein the polarizer includes polyvinyl alcohol, the release surface is bonded to a surface of the polarizer with an adhesive, and the adhesive includes polyvinyl alcohol.
18. An optical sheet member comprising the brightness enhancement film according to claim 14 and a polarizing plate including a polarizer, wherein the λ / 4 plate and the polarizer are directly bonded with an adhesive layer.
19. An optical sheet member comprising the brightness enhancement film according to claim 15 and a polarizing plate including a polarizer, wherein the alignment layer and the polarizer are directly bonded by an adhesive layer.
20. The optical sheet member according to claim 19, wherein both the polarizer and the adhesive layer contain polyvinyl alcohol.

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