KR20240135566A - Optical laminate - Google Patents

Abstract

(Problem) To provide an optical laminate capable of configuring an image display device in which an image can be viewed regardless of the display angle even when the image is viewed through polarized sunglasses, and in which the difference in color taste according to the display angle is reduced.
(Solution) An optical laminate having a first phase difference plate, a polarizer, a second phase difference plate, and an adhesive layer in this order, wherein the first phase difference plate satisfies the relationship of the following formula (1), and the second phase difference plate includes two or more phase difference layers including a liquid crystal cured product in which a polymerizable liquid crystal compound is polymerized, and satisfies the relationships of the following formulas (2) and (3).
1.0 ≤ Re1(450)/Re1(550) (1)
70㎚ ≤ Re2(450) ≤ 130㎚ (2)
Re2(450)/Re2(550) ≤ 1.0 (3)

Description

OPTICAL LAMINATE

The present invention relates to an optical laminate.

Conventionally, in image display devices, a method has been adopted in which a circular polarizing plate is placed on the viewing side of the image display panel to suppress the deterioration of visibility due to reflection of external light.

A circular polarizing plate is an optical laminate in which a polarizer and a phase difference plate are laminated. In a circular polarizing plate, external light directed toward an image display panel is converted into linearly polarized light by the polarizer, and then converted into circularly polarized light by the subsequent phase difference plate. The external light, which is circularly polarized, is reflected from the surface of the image display panel, but the rotation direction of the polarization plane is reversed during this reflection, and after being converted into linearly polarized light by the phase difference plate, it is blocked by the subsequent polarizer. As a result, the emission of external light to the outside is suppressed. As a configuration of a circular polarizing plate, a configuration having a phase difference plate including a cured product of a liquid crystal compound is known (for example, Patent Document 1).

Japanese Patent Publication No. 2016-27431

Foldable image display devices such as smartphones are usually configured to be used at different display angles, such as vertical and horizontal arrangements. When foldable image display devices are used outdoors, the displayed image may be viewed through polarized sunglasses. When the displayed image is viewed through polarized sunglasses, depending on the display angle, there may be cases where it cannot be viewed or there may be differences in the color taste of the viewed image.

The present invention aims to provide an optical laminate capable of configuring an image display device in which reflected light is suppressed, and the image can be viewed regardless of the display angle even when viewed through polarized sunglasses, and in which the difference in color taste according to the display angle is reduced.

The present invention provides the following optical laminate.

〔1〕 It has a first phase difference plate, a polarizer, a second phase difference plate, and an adhesive layer in this order,

The above first phase plate,

It is arranged so that the angle θ1 formed by the delayed axis with respect to the absorption axis of the polarizer is 40° to 50° or -40° to -50°, and also

If the in-plane phase difference value for light with a wavelength of λ nm is Re1(λ), it satisfies the relationship of the following equation (1),

The above second phase plate,

A polymerizable liquid crystal compound comprising two or more phase contrast layers including a polymerized liquid crystal cured product,

At least two of the above-mentioned two-layer or more phase-shifted layers have their ground axes intersecting each other within the plane,

An optical laminate that satisfies the relationships of equations (2) and (3) below, where Re2(λ) is the in-plane phase difference value for light having a wavelength of λ nm.

1.0 ≤ Re1(450)/Re1(550) (1)

70㎚ ≤ Re2(450) ≤ 130㎚ (2)

Re2(450)/Re2(550) ≤ 1.0 (3)

〔2〕 The optical laminate described in 〔1〕, wherein the first phase difference plate is a film obtained by stretching a thermoplastic resin film and has a thickness of 10 ㎛ to 100 ㎛.

〔3〕 The first phase difference plate is an optical laminate according to claim 1 or 2, wherein Re1(λ) satisfies the following equations (4) and (5).

100㎚ ≤ Re1(450) ≤ 130㎚ (4)

100㎚ ≤ Re1(550) ≤ 130㎚ (5)

〔4〕 Further, a protective film is disposed between the polarizer and the second phase difference plate,

The above protective film is an optical laminate as described in 〔1〕 or 〔2〕, having an in-plane phase difference value of 0 nm to 20 nm for light having a wavelength of 550 nm.

〔5〕 An optical laminate as described in 〔1〕 or 〔2〕, wherein at least two of the phase difference layers constituting the second phase difference plate have ground axes intersecting in the plane.

〔6〕 The optical laminate as described in 〔1〕 or 〔2〕, wherein among the two or more phase difference layers constituting the second phase difference plate, the first layer, which is the layer closest to the polarizer, has an angle θ2 of its ground axis with respect to the absorption axis of the polarizer of 10° to 20° or -10° to -20°.

〔7〕 An optical laminate as described in 〔1〕 or 〔2〕, wherein among the two or more phase difference layers constituting the second phase difference plate, the first layer, which is the layer closest to the polarizer, has an angle θ2, which its ground axis forms with respect to the absorption axis of the polarizer, the sign of which is opposite to the sign of the angle θ1.

〔8〕 The first phase difference plate further has a layer having a predetermined ultraviolet absorption characteristic on the surface opposite to the polarizer,

The above-described predetermined ultraviolet absorption characteristic is an optical laminate described in 〔1〕 or 〔2〕, which satisfies the relationships of the following equations (6), (7), and (8), when the transmittance of light having a wavelength of λ㎚ is Tr(λ).

Tr(450) ≥ 85％ (6)

30% ≤ Tr(420) ≤ 75% (7)

0% ≤ Tr(400) ≤ 10% (8)

According to the present invention, it is possible to provide an optical laminate capable of configuring an image display device in which reflected light is suppressed, and further, the image can be viewed regardless of the display angle even when viewed through polarized sunglasses, and further, the difference in color taste according to the display angle is reduced.

Fig. 1 is a schematic cross-sectional view schematically showing an example of an optical laminate of the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments below. In the drawings below, each component is shown with an appropriate scale adjusted to facilitate understanding, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

[Optical laminate]

The optical laminate of the present invention has a first phase difference plate, a polarizer, a second phase difference plate, and an adhesive layer in this order.

The first phase difference plate is arranged so that the angle θ1 that its ground axis forms with respect to the absorption axis of the polarizer is 40° to 50° or -40° to -50°, and further, when the in-plane phase difference value of light having a wavelength λ㎚ is Re1(λ), the relationship of the following equation (1) is satisfied.

1.0 ≤ Re1(450)/Re1(550) (1)

By arranging an optical laminate having a first phase difference plate satisfying the above formula (1) on the front surface of an image display device, even when the displayed image is viewed through polarized sunglasses, the image can be viewed regardless of the display angle, and furthermore, the difference in color taste according to the display angle is reduced, thereby improving visibility.

The second phase difference plate includes two or more phase difference layers including a liquid crystal cured product polymerized with a polymerizable liquid crystal compound, and the two or more phase difference films have their ground axes intersecting each other in the plane at least two of which satisfy the relationships of the following equations (2) and (3), when the in-plane phase difference value of light having a wavelength λ nm is Re2(λ).

70㎚ ≤ Re2(450) ≤ 130㎚ (2)

Re2(450)/Re2(550) ≤ 1.0 (3)

The two or more phase difference layers constituting the second phase difference plate are as follows:

1.0 ≤ Re2(450)/Re2(550) (1-2)

It is desirable to satisfy the relationship.

By disposing an optical laminate in which the second phase difference plate satisfies the relationships of the above formulas (2) and (3) and all of the two or more phase difference layers constituting the second phase difference plate satisfy the relationships of the formulas (1-2) on the front surface of an image display device, reflected light can be suppressed and coloring of reflected light can be suppressed.

Fig. 1 is a schematic cross-sectional view schematically showing an example of an optical laminate of the present embodiment. As shown in Fig. 1, the optical laminate (1) comprises, from the front side, a surface treatment layer (11), a first protective film (12), a first bonding layer (13), a polarizer (14), a second bonding layer (15), a second protective film (16), a third bonding layer (17), a second phase difference plate (18), and an adhesive layer (19), and these are laminated in this order in the thickness direction.

In this specification, a component including a polarizer is also referred to as a linear polarizing plate. The linear polarizing plate may be composed of only a polarizer, or may include components other than a polarizer. In an optical laminate (1), a layered portion including a surface treatment layer (11), a first protective film (12), a first bonded layer (13), a polarizer (14), a second bonded layer (15), and a second protective film (16) is referred to as a linear polarizing plate (10).

In the optical laminate (1), the first protective film (12) corresponds to the first phase difference plate. The first phase difference plate may be a component included in the linear polarizing plate, or may be a component provided separately from the linear polarizing plate. Each layer shown in Fig. 1 may be configured as a single layer, or may be configured as a multiple layer. The optical laminate (1) may have a configuration that has layers other than the layers shown in Fig. 1, or may have a configuration that does not have some of the layers shown in Fig. 1.

[Linear polarizing plate]

A linear polarizing plate is a film having a function of light absorption anisotropy, and is generally a film including a polarizer in which a dichroic dye is uniaxially aligned. In order to uniaxially align a dichroic dye, a film (hereinafter also referred to as a "polarizer") obtained by impregnating iodine or an organic dichroic dye into a polymer such as PVA and stretching it uniaxially, or an optically anisotropic layer (hereinafter also referred to as a "polarizing film") formed by aligning a dichroic dye and a polymerizable liquid crystal compound in a composition (hereinafter also referred to as a "polarizing film-forming composition") including a polymerizable liquid crystal compound and a dichroic dye, can be produced. That is, light is anisotropically absorbed by the dichroic dye incorporated in the stretched polymer or the polymerizable liquid crystal compound, thereby exhibiting a polarizing function.

The polarization performance of a linear polarizing plate can be measured using a spectrophotometer. For example, in the visible light wavelength range of 380 nm to 780 nm, the transmittance (T1) in the transmission axis direction (orientation vertical direction) and the transmittance (T2) in the absorption axis direction (orientation direction) can be measured by the double beam method using a device in which a prism polarizer is set in a spectrophotometer. The polarization performance in the visible light range can be calculated as the visibility-corrected single transmittance (Ty) and the visibility-corrected polarization degree (Py) by calculating the single transmittance and polarization degree at each wavelength using the following equations (11) and (12), and further performing visibility correction by a 2-degree field of view (C light source) of JIS Z 8701. In addition, by calculating the chromaticity a ^* and b ^* in the L ^* a ^* b ^* (CIE) color system using the chromaticity function of the C illuminant from the similarly measured transmittance, the color of a single linear polarizing plate (single color), the color of the linear polarizing plates arranged in parallel (parallel color), and the color of the linear polarizing plates arranged orthogonally (orthogonal color) are obtained. The closer the values of a ^* and b ^* are to 0, the more neutral the color can be determined.

Group penetration rate (%) = (T1 + T2)／2 … (11)

Polarization (%) = (T1 - T2)／(T1 + T2) × 100 … (12)

The visibility correction polarization degree Py of the linear polarizing plate is usually 80% or more, preferably 90% or more, more preferably 95% or more, still more preferably 98% or more, particularly preferably 99% or more, and if it is 99.9% or more, it can be preferably used for a liquid crystal display. Increasing the visibility correction polarization degree Py of the linear polarizing plate is advantageous in enhancing the antireflection function of the optical laminate. If the visibility correction polarization degree Py is less than 80%, the antireflection function may not be fully achieved when used as an antireflection film.

The visibility correction group transmittance Ty of the linear polarizing plate increases as it increases, the clarity at the time of white display increases, but as can be seen from the relationship between equations (11) and (12), if the group transmittance is made too high, there is a problem that the polarization degree decreases. Therefore, it is preferably 30% or more and 60% or less, more preferably 35% or more and 55% or less, even more preferably 40% or more and 50% or less, and even more preferably 40% or more and 45% or less. If the visibility correction group transmittance Ty is too high, the visibility correction polarization degree Py becomes too low, and when used as an antireflection film, the antireflection function may become insufficient.

<Polarizer formed from film>

A polarizer, which is a uniaxially stretched film impregnated with iodine or an organic dichroic dye in a polymer such as PVA, can be manufactured through a process of uniaxially stretching a polyvinyl alcohol-based resin film, a process of dyeing the polyvinyl alcohol-based resin film with a dichroic dye such as iodine to adsorb the dichroic dye, a process of treating the polyvinyl alcohol-based resin film to which the dichroic dye has been adsorbed with a boric acid aqueous solution, and a process of washing the film after the treatment with the boric acid aqueous solution.

The thickness of the polarizer is usually 30 ㎛ or less, preferably 18 ㎛ or less, more preferably 15 ㎛ or less, and even more preferably 10 ㎛ or less. The thickness is usually 1 ㎛ or more, and for example, 5 ㎛ or more may be sufficient.

The uniaxial stretching of a polyvinyl alcohol-based film can be performed before, simultaneously with, or after dyeing with a dichroic dye. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. Of course, the uniaxial stretching may be performed in multiple stages as shown here. For the uniaxial stretching, a method of uniaxially stretching in the film transport direction between rolls having different circumferential speeds, a method of uniaxially stretching in the film transport direction using a hot roll, a method of stretching in the width direction using a tenter, etc. can be employed. Furthermore, the uniaxial stretching may be performed by dry stretching in the air, or by wet stretching in which the polyvinyl alcohol-based film is swollen using a solvent such as water and stretching is performed. The stretching ratio is usually about 3 to 8 times. In addition, after applying an aqueous solution containing polyvinyl alcohol on a thermoplastic resin film, a drying treatment may be performed, and the film may be stretched together with the thermoplastic resin film using the above method.

Dyeing of a polyvinyl alcohol film with a dichroic dye can be carried out, for example, by a method of immersing the polyvinyl alcohol film in an aqueous solution containing a dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye.

<Polarizer formed from a coating film>

A polarizer, which is an optically anisotropic layer made of a polymer of a polymerizable liquid crystal compound containing a dichroic pigment, can be suitably used, for example, in flexible display applications, because its color can be arbitrarily controlled, its thickness can be significantly reduced, and it is non-shrinkable because it is not relaxed by thermal stretching.

A polarizer is formed by applying a polarizer-forming composition onto an alignment film formed on a substrate as needed, and aligning a dichroic dye included in the polarizer-forming composition. The polarizer is a film having a thickness of 0.1 µm or more and 5 µm or less, more preferably 0.3 µm or more and 4 µm or less, and even more preferably 0.5 µm or more and 3 µm or less. If the film thickness is thinner than this range, there are cases where the required light absorption is not obtained, and furthermore, if the film thickness is thicker than this range, the alignment control force by the alignment film decreases, and alignment defects tend to easily occur. In addition, the polarizer-forming composition may further include a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, and an adhesion improver.

The optical anisotropic layer in which a dichroic dye and a polymerizable liquid crystal compound are aligned horizontally with respect to a substrate plane preferably has a ratio (dichroic ratio) of the absorbance A1(λ) in the alignment direction to the absorbance A2(λ) in the vertical direction within the alignment plane for light having a wavelength λ㎚ of 7 or more, more preferably 20 or more, and even more preferably 40 or more. The higher this value, the better the absorption selectivity of the polarizing plate. Although it varies depending on the type of dichroic dye, it is about 5 to 10 in the case of a liquid crystal cured film cured in a nematic liquid crystal phase state.

By mixing two or more types of dichroic dyes with different absorption wavelengths, polarizers of various colors can be produced, and a polarizer having absorption in the entire visible light range can be produced. By producing a polarizer having such absorption characteristics, it can be expanded into various uses.

(polymerizable liquid crystal compound)

A polymerizable liquid crystal compound is a compound having a polymerizable group and also having liquid crystal properties (hereinafter, also referred to as a polymerizable liquid crystal). The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can participate in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, an oxetanyl group, and the like. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and a methacryloyloxy group or an acryloyloxy group is more preferable. The liquid crystal may be either a thermotropic liquid crystal or a lyotropic liquid crystal, but when mixed with a dichroic dye described later, a thermotropic liquid crystal is preferred. The polymerizable liquid crystal compound may be a monomer or a polymer polymerized with a dimer or higher polymerization.

When the polymerizable liquid crystal compound is a thermotropic liquid crystal, it may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase, or it may be a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. From the viewpoint of being able to exhibit high dichroism, the liquid crystal state exhibited by the polymerizable liquid crystal compound is preferably a smectic phase, and a higher-order smectic phase is more preferable from the viewpoint of high performance. Among these, a higher-order smectic liquid crystal compound that forms a Smectic B phase, a Smectic D phase, a Smectic E phase, a Smectic F phase, a Smectic G phase, a Smectic H phase, a Smectic I phase, a Smectic J phase, a Smectic K phase, or a Smectic L phase is more preferable, and a higher-order smectic liquid crystal compound that forms a Smectic B phase, a Smectic F phase, or a Smectic I phase is still more preferable. When the liquid crystal phase formed by the polymerizable liquid crystal is one of these higher-order smectic phases, a polarizer having higher polarization performance can be manufactured. In addition, a polarizer having such high polarization performance obtains a Bragg peak derived from a higher-order structure such as a hexahedral phase or a crystal phase in X-ray diffraction measurements. The Bragg peak is a peak derived from a periodic structure of molecular orientation, and a film having a periodic interval of 3 to 6 Å can be obtained. The polarizer of the present invention preferably includes a polymer of a polymerizable liquid crystal aligned in a smectic phase, from the viewpoint of obtaining higher polarization characteristics.

As the polymerizable liquid crystal compound, one type may be used alone, or two or more types may be used in combination. The polymerizable liquid crystal composition containing another compound described below may contain another polymerizable liquid crystal compound other than the polymerizable liquid crystal compound, as long as the effects of the present invention are not impaired. However, from the viewpoint of obtaining a polarizer with a high degree of alignment order, the proportion of the polymerizable liquid crystal compound with respect to the total mass of all polymerizable liquid crystal compounds contained in the polymerizable liquid crystal composition is preferably 51 mass% or more, more preferably 70 mass% or more, and even more preferably 80 mass% or more.

The content of the polymerizable liquid crystal compound in the polarizer-forming composition of the present invention is preferably 40 to 99.9 mass%, more preferably 60 to 99 mass%, and even more preferably 70 to 99 mass%, based on the solid content of the polymerizable liquid crystal composition. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to increase. In addition, in this specification, the solid content refers to the total amount of components excluding the solvent from the polymerizable liquid crystal composition.

(Dichromatic pigment)

A dichroic dye is a dye that has different absorbances in the long axis direction and in the short axis direction of the molecule. As a dichroic dye, it is preferable to have a property of absorbing visible light, and it is more preferable to have an absorption maximum wavelength (λMAX) in the range of 380 to 680 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, and among them, azo dyes are preferable. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbenazo dyes, and bisazo dyes and trisazo dyes are preferable. A dichroic dye may be used alone or in combination, but in order to obtain absorption in the entire visible light range, it is preferable to combine two or more types of dichroic dyes, and it is more preferable to combine three or more types of dichroic dyes.

As an azo dye, for example, a compound represented by formula (XVI) (hereinafter, sometimes referred to as “compound (XVI)”) can be mentioned.

T ¹ -A ¹ (-N=NA ² ) _p -N=NA ³ -T ² (XVI)

[In formula (XVI), A ¹ and A ² and A ³ independently represent a 1,4-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, a benzoic acid phenyl ester group which may have a substituent, a 4,4'-stilbenylene group which may have a substituent, or a divalent heterocyclic group which may have a substituent, and T ¹ and T ² are electron-withdrawing groups or electron-releasing groups and are located at a position substantially 180° with respect to the azo bond plane. p represents an integer from 0 to 4. When p is 2 or more, each A ² may be the same or different. In a range showing absorption in the visible range, the -N=N- bond may be replaced by a -C=C-, -COO-, -NHCO-, -N=CH- bond.]

The content of the dichroic dye (the total amount when multiple types are included) is usually 1 to 60 parts by mass, preferably 1 to 40 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound, from the viewpoint of obtaining good light absorption characteristics. If the content of the dichroic dye is less than this range, light absorption becomes insufficient and sufficient polarization performance cannot be obtained, and if it is more than this range, the alignment of the liquid crystal molecules may be inhibited.

<Method for manufacturing a polarizer formed from a film>

Polarizers are usually manufactured through a process of uniaxially stretching a PVA film, a process of adsorbing a dichroic dye by dyeing the PVA film with a dichroic dye, a process of crosslinking the PVA film to which the dichroic dye has been adsorbed by treating it with a boric acid aqueous solution, and a process of washing the film after the crosslinking treatment with the boric acid aqueous solution (hereinafter also referred to as boric acid treatment).

The uniaxial stretching of the PVA film can be performed before, simultaneously with, or after dyeing with a dichroic dye. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. Of course, the uniaxial stretching may be performed in multiple stages as shown here. For the uniaxial stretching, a method of uniaxially stretching in the film transport direction between rolls having different peripheral speeds, a method of uniaxially stretching in the film transport direction using a hot roll, a method of stretching in the width direction using a tenter, etc. can be employed. In addition, the uniaxial stretching may be performed by dry stretching in the air, or by wet stretching in which the PVA film is swollen using a solvent such as water and stretching is performed. The stretching ratio is usually about 3 to 8 times.

Dyeing of a PVA film with a dichroic dye can be carried out, for example, by a method of immersing the PVA film in an aqueous solution containing a dichroic dye. As the dichroic dye, iodine or a dichroic organic dye is specifically used. In addition, it is preferable to perform a treatment of swell by immersing the PVA film in water before the dyeing treatment.

When iodine is used as a dichroic dye, a method of dyeing by immersing a PVA film in an aqueous solution containing iodine and potassium iodide is usually adopted. The iodine content in this aqueous solution is usually about 0.01 to 1 part by mass per 100 parts by mass of water, and the potassium iodide content is usually about 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40°C. In addition, the immersion time in this aqueous solution (dyeing time) is usually about 20 to 1,800 seconds.

Meanwhile, when a dichroic organic dye is used as a dichroic dye, a method of dyeing a PVA film by immersing it in an aqueous solution containing a water-soluble dichroic organic dye is usually adopted. The content of the dichroic organic dye in this aqueous solution is usually about 0.0001 to 10 parts by mass, and preferably about 0.001 to 1 part by mass, per 100 parts by mass of water. This dye aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the dichroic organic dye aqueous solution used for dyeing is usually about 20 to 80°C. In addition, the immersion time in this aqueous solution (dyeing time) is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with a dichroic dye can be carried out by a method of immersing the dyed PVA film in a boric acid-containing aqueous solution. The content of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by mass, and preferably about 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by mass, and preferably about 5 to 12 parts by mass, per 100 parts by mass of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, and preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

The PVA film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be performed, for example, by a method of immersing the PVA film treated with boric acid in water. The temperature of the water in the water washing treatment is usually about 5 to 40°C. Also, the immersion time is usually about 1 to 120 seconds.

After washing, a drying process is performed, and a polarizer is obtained. The drying process can be performed using a hot air dryer or a far-infrared heater. The temperature of the drying process is usually about 30 to 100°C, and preferably about 50 to 80°C. The time of the drying process is usually about 60 to 600 seconds, and preferably about 120 to 600 seconds. By the drying process, the moisture content in the polarizer is reduced to a practical level. The moisture content is usually about 5 to 20 mass%, and preferably 8 to 15 mass%, with respect to the total mass of the polarizer. If the moisture content is 5 mass% or more, the polarizer has sufficient flexibility, so that damage or breakage after drying can be suppressed. In addition, if the moisture content is 20 mass% or less, the polarizer has sufficient thermal stability.

In this manner, a polarizer in which a dichroic dye is adsorbed and aligned on a PVA film can be manufactured.

In addition, the polarizer obtained above may also have a protective film bonded to one or both sides thereof using the adhesive.

<Protective film>

The protective film has the function of protecting the surface of the polarizer. The polarizer and the protective film may be directly laminated with each other. Here, “directly laminated” includes a state in which the protective film is laminated on the polarizer by the self-adhesiveness of the protective film, and a state in which the protective film is laminated via an adhesive or a pressure-sensitive adhesive. The protective film may be surface-treated (e.g., corona treatment, etc.) to improve adhesion to the polarizer, and may be formed with a thin layer such as a primer layer (also called an easy-adhesive layer).

As a protective film, for example, a resin film having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and stretchability can be used. The resin film may be a thermoplastic resin film. Specific examples of such resins include cellulose-based resins such as triacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone-based resins; polysulfone-based resins; polycarbonate-based resins; polyamide-based resins such as nylon and aromatic polyamide; polyimide-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin-based resins having cyclo-based and norbornene structures (also called norbornene-based resins); (meth)acrylic-based resins such as polymethyl methacrylate; polyarylate-based resins; polystyrene-based resins; polyvinyl alcohol-based resins, and mixtures thereof. Protective films of such materials are readily available on the market. In addition, thermosetting resins or ultraviolet-curable resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone may also be mentioned.

Examples of chain polyolefin resins include chain olefin homopolymers such as polyethylene resin (polyethylene resin which is a homopolymer of ethylene or a copolymer mainly composed of ethylene), polypropylene resin (polypropylene resin which is a homopolymer of propylene or a copolymer mainly composed of propylene), and copolymers composed of two or more types of chain olefins.

Cyclic polyolefin resin is a general term for resins polymerized using cyclic olefins as polymerization units, and examples thereof include resins described in Japanese Patent Application Laid-Open No. 1-240517, Japanese Patent Application Laid-Open No. 3-14882, and Japanese Patent Application Laid-Open No. 3-122137. Specific examples of cyclic polyolefin resins include ring-opened (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain olefins such as ethylene and propylene (typically random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among these, norbornene resins using a norbornene monomer such as norbornene or a polycyclic norbornene monomer as the cyclic olefin are preferably used.

Polyester resins are resins having an ester bond in the main chain, and are generally polycondensates of polyhydric carboxylic acids or derivatives thereof and polyhydric alcohols. As the polyhydric carboxylic acid or derivatives thereof, dihydric dicarboxylic acids or derivatives thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. As the polyhydric alcohol, dihydric diols can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A representative example of a polyester resin is polyethylene terephthalate, which is a polycondensation of terephthalic acid and ethylene glycol.

Cellulose ester resins are esters of cellulose and fatty acids. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, copolymers having multiple types of polymerization units constituting these cellulose ester resins, and those in which some of the hydroxyl groups are modified with other substituents are also included. Of these, cellulose triacetate (triacetyl cellulose) is particularly preferable.

(Meth)acrylic resins are resins whose main constituent monomer is a compound having a (meth)acryloyl group. Specific examples of (meth)acrylic resins include, for example, poly(meth)acrylic acid esters such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymers; methyl methacrylate-(meth)acrylic acid ester copolymers; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymers; methyl (meth)acrylate-styrene copolymers (MS resins, etc.); and copolymers of methyl methacrylate and a compound having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate-(meth)acrylic acid norbornyl copolymers, etc.). Preferably, a polymer containing a poly(meth)acrylic acid C1-6 alkyl ester as a main component, such as poly(meth)acrylate methyl, is used, and more preferably, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100 wt%, preferably 70 to 100 wt%) is used.

Polycarbonate resins are made of polymers in which monomer units are bonded via carbonate groups. The polycarbonate resins may be resins called modified polycarbonates in which the polymer skeleton is modified, or copolymerized polycarbonates. Details of polycarbonate resins are described in, for example, Japanese Patent Application Laid-Open No. 2012-31370. The description of the above patent document is incorporated herein by reference.

The thickness of the protective film is preferably 0.1 ㎛ to 60 ㎛, more preferably 0.5 ㎛ to 40 ㎛, and even more preferably 1 ㎛ to 30 ㎛.

The protective film can be used by arranging it so that it faces the viewing side from the polarizer. Therefore, the protective film may be subjected to surface treatment such as hard coating treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment, as necessary. In addition/or, the protective film may be subjected to treatment (typically, imparting an (alternative) circular polarization function or imparting an ultra-high phase difference) to improve visibility when viewed through polarizing sunglasses, as necessary. By performing such treatment, excellent visibility can be realized even when the display screen is viewed through a polarizing lens such as polarizing sunglasses. Therefore, the polarizing plate with a phase difference plate can be suitably applied to an image display device that can be used outdoors. In the optical laminate (1), the first protective film (11) disposed on the viewing side from the polarizer (14) is a first phase difference plate to which a phase difference is imparted. The first phase difference will be described in detail later.

A protective film can be produced by stretching a film including the thermoplastic resin described above. Examples of the stretching treatment include uniaxial stretching and biaxial stretching. Examples of the stretching direction include the machine flow direction (MD) of the unstretched film, the direction orthogonal thereto (TD), and the direction oblique to the machine flow direction (MD). The biaxial stretching may be simultaneous biaxial stretching in which stretching is performed in two stretching directions simultaneously, or may be sequential biaxial stretching in which stretching is performed in a predetermined direction and then in another direction. The stretching treatment can be performed, for example, by using two or more pairs of nip rolls with a large outlet speed to stretch in the longitudinal direction (machine flow direction: MD), or by gripping both ends of the unstretched film with a chuck and spreading it in the direction orthogonal to the machine flow direction (TD). At this time, it is possible to control the phase difference value and wavelength dispersion by adjusting the thickness of the film or adjusting the stretching ratio. In addition, it is possible to control the wavelength dispersion value by adding a wavelength dispersion adjusting agent to the resin.

The above protective film may contain any appropriate additives depending on the purpose. Examples of the additives include antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light stabilizers, ultraviolet absorbers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic fillers or inorganic fillers; resin modifiers; plasticizers; lubricants; and phase difference reducing agents. The types, combinations, and contents of the additives contained may be appropriately set depending on the purpose or desired characteristics.

In addition, a surface treatment layer may be provided on the outer surface of the protective film to impart desired surface optical properties or other characteristics. Specific examples of the surface treatment layer include a hard coating layer, an anti-glare layer, an anti-reflection layer, an antistatic layer, and an anti-fouling layer. The method for forming the surface treatment layer is not particularly limited, and a known method can be used. The surface treatment layer may be formed on one side of the protective film, or may be formed on both sides.

In the optical laminate (1), the first protective film (12) and the second protective film (16) correspond to the protective films described above. In the optical laminate (1), the first protective film (11) is a protective film arranged on the viewing side from the polarizer (14), and a surface treatment layer (11) is formed on the viewing side surface thereof. The second protective film (16) is arranged between the polarizer (14) and the second phase difference plate (18). From the viewpoint of suppressing coloring of reflected light of an image display device observed in a diagonal direction, the second protective film (16) preferably has an in-plane phase difference value of light having a wavelength of 550 nm of 0 nm to 20 nm, more preferably 0 nm to 10 nm, most preferably 0 nm to 5 nm, and ideally 0 nm.

<Surface treatment layer>

The surface treatment layer has the function of increasing the surface hardness of the protective film and is provided for the purpose of preventing surface scratches, etc. The surface treatment layer preferably has a pencil hardness of H or harder as measured by a pencil hardness test (measured by placing an optical film having a surface treatment layer on a glass plate) specified in JIS K 5600-5-4:1999 "General testing methods for paints - Part 5: Mechanical properties of coatings - Section 4: Scratch hardness (pencil method)".

The material forming the surface treatment layer is generally one that is hardened by heat or light. Examples thereof include organic hard coating materials such as organic silicon, melamine, epoxy, (meth)acrylic, and urethane (meth)acrylate, and inorganic hard coating materials such as silicon dioxide. Among these, urethane (meth)acrylate or polyfunctional (meth)acrylate hard coating materials are preferably used because they have good adhesion to the protective film and excellent productivity.

The surface treatment layer may contain various fillers, depending on the purpose, for the purpose of adjusting the refractive index, improving the bending elastic modulus, stabilizing the volume shrinkage rate, and further improving heat resistance, antistatic properties, antiglare properties, etc. In addition, the surface treatment layer may contain additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an anti-foaming agent.

The surface treatment layer may contain additives to further improve strength. The additives are not limited, and may include inorganic fine particles, organic fine particles, or mixtures thereof. In addition, the thickness of the surface treatment layer is preferably thick to provide hardness, but if it is too thick, it may be easily broken when cut, so it may be 1 ㎛ to 20 ㎛, or 2 ㎛ to 10 ㎛. The thickness of the surface treatment layer is preferably 3 ㎛ to 7 ㎛.

The antiglare layer is a layer having a fine rough surface, and is preferably formed using the hard coating material described above.

An antiglare layer having a fine uneven shape on its surface can be formed by 1) a method of forming a coating film containing fine particles on a stretched film and providing unevenness based on the fine particles, 2) a method of forming a coating film containing or not containing fine particles on a stretched film and then pressing it against a mold (roll, etc.) having an uneven shape on its surface to transfer the uneven shape (also called an embossing method), etc.

The antireflection layer is a layer for weakening the external light reflection of the protective film surface for a person observing the protective film, and usually has a reflectance of 1.5% or less for visible light. Such an antireflection layer with a reflectance is typically formed by laminating a high refractive index layer having a high refractive index and a low refractive index layer having a low refractive index, or by using the method or material described in Japanese Patent Application Laid-Open No. 2021-6929. By adjusting these refractive indices and the thickness of each layer, the reflected light from each layer can be weakened mutually, so that an excellent antireflection function is exhibited.

The antireflection layer composed of a high refractive index layer and a low refractive index layer is preferably manufactured by using a coating composition capable of forming each of the high refractive index layer and the low refractive index layer, as will be described in detail later, because the operation is very simple. Here, an example of a coating composition capable of forming each of the high refractive index layer and the low refractive index layer is given. This coating composition is liquid, and contains an appropriate curable resin and, if necessary, an additive. A coating composition capable of forming a high refractive index layer (coating solution for forming a high refractive index layer) is formed by dissolving, for example, a curable resin such as urethane acrylate and an initiator for photopolymerization (photopolymerization initiator) such as acetophenone, benzophenone, benzyl dimethyl ketal, α-hydroxyalkyl phenone, α-aminoalkyl phenone or thioxanthone in a solvent such as methyl ethyl ketone or methyl isobutyl ketone. In order to improve the coating property, a leveling agent, preferably a fluorine-based leveling agent, may be included. In addition, a coating composition capable of forming a low refractive index layer (coating solution for forming a low refractive index layer) is formed by dissolving a binder resin such as polyethylene glycol diacrylate or pentaerythritol (tri/tetra) acrylate as a curable resin, an initiator for photopolymerization (photopolymerization initiator) such as acetophenone, benzophenone, benzyl dimethyl ketal, α-hydroxyalkyl phenone, α-aminoalkyl phenone or thioxanthone in a solvent such as 1-methoxy-2-propyl acetate or methyl isobutyl, and dispersing silica particles in the solution. A fluorine-based leveling agent may be included in order to further improve the coating property. In addition, the coating compositions capable of forming each of the high refractive index layer and the low refractive index layer mentioned herein are merely examples, and it is preferable to optimize the coating solution for forming the high refractive index layer and the coating solution for forming the low refractive index layer, respectively, depending on the characteristics of the antireflection layer to be formed.

The antireflection layer may include, for example, a low-refractive-index layer. Additionally, it may have a multilayer structure further including a high-refractive-index layer and/or a medium-refractive-index layer between the protective film and the low-refractive-index layer.

The low-refractive-index layer can be formed by a method of coating a coating solution containing a cured product of the above-described curable resin or a light-transmitting resin such as a metal alkoxide-based polymer and inorganic particles, and then curing the coating layer as needed. As the inorganic particles, for example, low-refractive-index particles such as LiF (refractive index 1.4), MgF (refractive index 1.4), 3NaF·AlF (refractive index 1.4), AlF (refractive index 1.4), Na ₃ AlF ₆ (refractive index 1.33), and hollow silica particles, etc. can be exemplified.

The antistatic layer is provided for the purpose of imparting conductivity to the surface of the protective film and suppressing the influence of static electricity. For the formation of the antistatic layer, for example, a method of applying a resin composition containing a conductive material (antistatic agent) onto the protective film can be adopted. For example, by allowing an antistatic agent to coexist with the hard coating material used for forming the hard coating layer described above, an antistatic hard coating layer can be formed.

The antifouling layer is provided to provide water-repellent properties, oil-repellent properties, sweat resistance, antifouling properties, etc. A preferable material for forming the antifouling layer is a fluorine-containing organic compound. Examples of the fluorine-containing organic compound include fluorocarbons, perfluorosilanes, and polymer compounds thereof. The method for forming the antifouling layer can use a physical vapor deposition method, a chemical vapor deposition method, a wet coating method, etc., representative examples of which are deposition or sputtering. The average thickness of the antifouling layer is usually about 1 to 50 nm, and preferably 3 to 35 nm.

[1st phase plate]

The first phase difference plate may include a layer that expresses a phase difference, and the layer that expresses a phase difference may be a phase difference film formed from a thermoplastic resin film by stretching or the like, or may be a layer (hereinafter also referred to as a "phase difference film") made of a polymer in an aligned state of a polymerizable liquid crystal compound and exhibiting optical anisotropy. A film obtained by stretching a thermoplastic resin film is preferable from the viewpoint of scratch resistance, a cycloolefin polymer film or a triacetyl cellulose film is more preferable from the viewpoint of optical use, and a cycloolefin polymer film is more preferable from the viewpoint of versatility. When the first phase difference plate is a film obtained by stretching a thermoplastic resin film, the thickness thereof is preferably 10 µm to 100 µm, and from the viewpoint of layer thickness design of the optical laminate, it is more preferable 15 µm to 80 µm, and even more preferably 20 µm to 50 µm.

In the case where the first phase difference plate is a phase difference film, the optical laminate may have a configuration in which the first protective film, which is a component of the linear polarizing plate, also serves as the first phase difference plate, or may have a configuration in which the first phase difference plate is provided separately from the linear polarizing plate. In the case where the first phase difference plate has a phase difference film, the phase difference film can be obtained by the method for forming the phase difference layer of the second phase difference plate described later, except that a polymerizable liquid crystal compound having regular dispersion properties is selected so as to exhibit regular dispersion characteristics (satisfying formula (1)).

The first phase difference plate is arranged so that the angle θ1 that its ground axis forms with respect to the absorption axis of the polarizer is 40° to 50° or -40° to -50°, and preferably about 45° or about -45°. When the in-plane phase difference value of the first phase difference plate for light having a wavelength λ㎚ is Re1(λ), the relationship of the following equation (1) is satisfied, and preferably the relationship of the following equation (1a) is further satisfied.

1.0 ≤ Re1(450)/Re1(550) (1)

1.0 ≤ Re1(550)/Re1(650) (1a)

(In the equation, Re1(450) represents the in-plane phase difference value of the first phase difference plate for light having a wavelength of 450 nm, Re1(550) represents the in-plane phase difference value for light having a wavelength of 550 nm, and Re1(650) represents the in-plane phase difference value of the first phase difference plate for light having a wavelength of 650 nm.)

The first phase plate preferably satisfies the following equations (4) and (5) for Re1(λ).

100㎚ ≤ Re1(450) ≤ 130㎚ (4)

100㎚ ≤ Re1(550) ≤ 130㎚ (5)

By having the first phase difference plate satisfy the above equations (1) and (4), an optical laminate can be provided that enables the display image to be viewed regardless of the display angle even when viewed through polarized sunglasses, and further enables the configuration of an image display device in which the difference in color taste according to the display angle is reduced. Although the phase difference value is often designed based on light having a wavelength of 550 nm, it is thought that it is important for solving the problem that the phase difference value for light having a wavelength of 450 nm be within a predetermined range.

When "Re1(450)/Re1(550)" of the first phase difference plate is less than 1.0, the difference in color taste according to the display angle becomes large. Preferably, it is 1.00 or more and 1.3 or less, more preferably 1.02 or more and 1.2 or less, and even more preferably 1.03 or more and 1.1 or less. The value of "Re1(450)/Re1(550)" can be arbitrarily adjusted by adjusting the material of the phase difference film, or by adjusting the mixing ratio of the polymerizable liquid crystal compound, the lamination angle of a plurality of optically anisotropic layers, or the phase difference value.

When the layer expressing the phase difference included in the first phase difference plate is a phase difference film, its thickness is preferably 0.5 to 5 ㎛, more preferably 0.8 to 4 ㎛, and even more preferably 1 to 3 ㎛.

[2nd phase plate]

The second phase difference plate includes a liquid crystal cured product in which a polymerizable liquid crystal compound is polymerized, and includes two or more phase difference layers which are phase difference films exhibiting optical anisotropy. When the second phase difference plate includes, for example, two phase difference layers, the phase axes of the two phase difference layers are arranged so as to intersect each other in the plane. When the second phase difference plate has three or more phase difference layers, it is preferable that the phase axes of two of the three or more phase difference layers are arranged so as to intersect each other in the plane. It is also preferable that the phase axes of all the phase difference layers of the three or more layers are arranged in different directions in the plane, that is, the phase axes of any two of the phase difference layers of all the phase difference layers of the three or more layers are arranged so as to intersect each other.

The second phase difference plate satisfies the relationships of equations (2) and (3) below, when the in-plane phase difference value of light with a wavelength of λ nm is Re2(λ).

70㎚ ≤ Re2(450) ≤ 130㎚ (2)

Re2(450)/Re2(550) ≤ 1.0 (3)

In order to highly achieve the antireflection function which is the purpose of the present invention, the second phase difference plate should preferably have a λ/4 layer function (i.e., a π/2 phase difference function) in the entire visible light range. Specifically, it may be a reverse wavelength-dispersion λ/4 layer, or it is preferable that it be a combination of a forward wavelength-dispersion λ/2 layer and a forward wavelength-dispersion λ/4 layer. Furthermore, from the viewpoint of being able to compensate for the antireflection function in the diagonal direction, it is preferable that it further includes a layer having anisotropy in the thickness direction (positive C plate). Furthermore, each optically anisotropic layer may have a tilt orientation or may form a cholesteric alignment state.

The second phase difference plate may be, for example, configured such that all of the phase difference layers including the liquid crystal cured product are positive A plates, and furthermore, the ground axes of the phase difference layers intersect each other within the plane. Furthermore, from the viewpoint of suppressing coloration of reflected light of the image display device observed in the diagonal direction, it is preferable that the λ/2 layer be a negative A plate.

<Phase barrier>

It is preferable to form a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as a “composition for forming a phase contrast film”) by coating it on a transparent substrate and forming an optically anisotropic layer made of a polymer in which the polymerizable liquid crystal compound is aligned, in that thinning and wavelength dispersion characteristics can be arbitrarily designed. In addition, the composition for forming a phase contrast film may further contain a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, and an adhesion improver.

The phase contrast film is usually formed by applying a phase contrast film-forming composition onto an alignment film formed on a substrate, and polymerizing a polymerizable liquid crystal compound included in the phase contrast film-forming composition. The phase contrast film is usually a film cured in a state in which the polymerizable liquid crystal compound is aligned, and in order to cause a phase difference within the viewing surface, it is necessary to be a cured film in which the polymerizable liquid crystal compound is polymerized in a state in which the polymerizable group is aligned in a horizontal direction with respect to the substrate surface. At this time, if the polymerizable liquid crystal compound is a rod-shaped liquid crystal, it may be a positive A plate, and if the polymerizable liquid crystal compound is a disc-shaped liquid crystal, it may be a negative A plate.

The thickness of the phase contrast film is usually 10 ㎛ or less, preferably 5 ㎛ or less, and more preferably 0.3 ㎛ or more and 3 ㎛ or less. It is preferably a coating layer formed by polymerizing one or more polymerizable liquid crystals.

[Composition combining 2-layer and 4-layer λ/wavelength dispersion]

As a second phase difference plate, a configuration combining a cyclic dispersive λ/2 layer and a cyclic dispersive λ/4 layer is known as one of methods for achieving anti-reflection performance. For example, the cyclic dispersive λ/2 layer is a negative A plate, and the cyclic dispersive λ/4 layer is a positive A plate. It is preferable that the ground axis of the cyclic dispersive λ/2 layer and the ground axis of the cyclic dispersive λ/4 layer intersect at an intersection angle of, for example, 50° to 70° in the plane. The intersection angle referred to here means the narrower intersection angle among the intersection angles of the two ground axes.

With respect to the absorption axis of the polarizer, the slow axis of the regular dispersive λ/2 layer is, for example, 10° to 20°, preferably 12° to 18°, and more preferably about 15°, and the slow axis of the regular dispersive λ/4 layer is, for example, 70° to 80°, more preferably 72° to 78°, and even more preferably about 75°.

In another embodiment, with respect to the absorption axis of the polarizer, the slow axis of the regular dispersive λ/2 layer is, for example, -10° to -20°, preferably -12° to -18°, more preferably about -15°, and the slow axis of the regular dispersive λ/4 layer is, for example, -70° to -80°, more preferably -72° to -78°, more preferably about -75°.

In another embodiment, the slow axis of the regular dispersive λ/2 layer is, for example, 70° to 80°, preferably 72° to 78°, more preferably about 75°, with respect to the absorption axis of the polarizer, and the slow axis of the regular dispersive λ/4 layer is, for example, 10° to 20°, more preferably 12° to 18°, more preferably about 15°.

In another embodiment, the slow axis of the regular dispersive λ/2 layer is, for example, -70° to -80°, preferably -72° to -78°, more preferably about -75°, with respect to the absorption axis of the polarizer, and the slow axis of the regular dispersive λ/4 layer is, for example, -10° to -20°, more preferably -12° to -18°, and even more preferably about -15°.

When the in-plane phase difference value at wavelength λ is Re(λ), it is obtained by combining layers having optical properties represented by equations (21), (23), and (24) and layers having optical properties represented by equations (22), (23), and (24) in a specific ground-axis relationship.

100㎚ ＜ Re(550) ＜ 150㎚ (21)

150㎚ ＜ Re(550) ＜ 320㎚ (22)

Re(450)/Re(550) ≥ 1.00 (23)

1.00 ≥ Re(650)/Re(550) (24)

In Equation (21), the preferable range of Re(550) is 100 nm to 150 nm, more preferably 105 nm to 145 nm, and even more preferably 110 nm to 140 nm. In addition, in Equation (22), the preferable range of Re(550) is 150 nm to 320 nm, more preferably 170 nm to 310 nm, and even more preferably 210 nm to 300 nm.

As a method for combining the above-mentioned configurations, well-known methods such as Japanese Patent Application Laid-Open No. 2015-163935 and WO2013／137464 can be cited. From the viewpoint of viewing angle compensation, it is preferable to use a λ/2 layer, which is a disk-shaped polymerizable liquid crystal compound, and a λ/4 layer, which is a rod-shaped polymerizable liquid crystal compound.

As a polymerizable liquid crystal compound in the form of a disk, for example, a compound containing a group represented by the formula (W) (hereinafter sometimes referred to as a polymerizable liquid crystal compound (C)) can be mentioned.

[In formula (W), R ⁴⁰ represents the following formulas (W-1) to (W-5).

X ⁴⁰ and Z ⁴⁰ represent an alkanediyl group having 1 to 12 carbon atoms, and a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, -CH ₂ - constituting the alkanediyl group may be substituted with -O- or -CO-.

As polymerizable liquid crystals of a rod shape, examples thereof include compounds represented by formula (Ⅰ), formula (Ⅱ), formula (Ⅲ), formula (IV), formula (V), or formula (VI).

P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (Ⅰ)

P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (Ⅱ)

P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (Ⅲ)

P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (Ⅳ)

P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (Ⅴ)

P11-B11-E11-B12-A11-B13-A12-F11 (Ⅵ)

(In the formula, A12 to A14 are each independently synonymous with A11, B14 to B16 are each independently synonymous with B12, B17 is synonymous with B11, and E12 is synonymous with E11. F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxy group, a methylol group, a formyl group, a sulfo group (-SO ₃ H), a carboxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom, and -CH ₂ - constituting the alkyl group and the alkoxy group may be substituted with -O-.)

[Other components]

In addition to the configuration combining the above-mentioned wavelength-dispersive λ/2 layer and wavelength-dispersive λ/4 layer, there are no particular restrictions on configurations having tilt or cholesteric orientation as long as they achieve an anti-reflection function, and examples thereof include known configurations disclosed in WO2021/060378, WO2021/132616, and WO2021/132624.

The content of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and even more preferably 90 to 95 parts by mass, per 100 parts by mass of the solid content of the polymerizable liquid crystal composition. When the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of the orientation of the resulting liquid crystal cured film. In addition, in this specification, the solid content of the polymerizable liquid crystal composition means all components excluding volatile components such as organic solvents from the polymerizable liquid crystal composition.

The in-plane retardation value of the second phase contrast film can be adjusted according to the thickness of the phase contrast film. Since the in-plane retardation value is determined by the following equation (8), Δn(λ) and the film thickness d can be adjusted to obtain a desired in-plane retardation value (Re2(λ)). The thickness of the phase contrast film is preferably 0.5 µm to 5 µm, more preferably 1 µm to 3 µm. The thickness of the phase contrast film can be measured by an interference thickness meter, a laser microscope, or a stylus-type thickness meter. In addition, Δn(λ) depends on the molecular structure of the polymerizable liquid crystal compound described later.

Re2(λ) = d × Δn(λ) … (8)

(In the formula, Re2(λ) represents the in-plane phase difference value at wavelength λ㎚, d represents the film thickness, and Δn(λ) represents the birefringence at wavelength λ㎚.)

<Description>

As the substrate, a glass substrate and a film substrate can be mentioned, and a film substrate is preferable, and a long roll film is more preferable in that it can be continuously manufactured. As the resin constituting the film substrate, for example, polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide, and polyphenylene oxide; and the like plastics can be mentioned. Among these, from the viewpoint of transparency, etc. when used for optical film purposes, a film substrate selected from among triacetyl cellulose, cyclic olefin resin, polymethacrylic acid ester, and polyethylene terephthalate is more preferable.

Examples of commercially available cellulose ester substrates include "Fuji Tac Film" (manufactured by FUJIFILM Corporation); "KC8UX2M", "KC8UY", and "KC4UY" (all manufactured by KONICA MINOLTA OPTO, INC.).

Examples of commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona, Germany), "ARTON" (registered trademark) (manufactured by JSR Corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (all manufactured by Zeon Corporation), and "APEL" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). These cyclic olefin resins can be formed into a film by a known means such as a solvent casting method or a melt extrusion method, and used as a substrate. A commercially available cyclic olefin resin substrate can also be used. Examples of commercially available cyclic olefin resin substrates include “ESINA” (registered trademark), “SCA40” (registered trademark) (all manufactured by Sekisui Chemical Company, Limited), “ZEONOR FILM” (registered trademark) (manufactured by Optes Co., Ltd.), and “ARTON FILM” (registered trademark) (manufactured by JSR Corporation).

The thickness of the substrate is preferably thin in terms of mass that allows practical handling, but if it is too thin, the strength decreases and the processability tends to decrease. The thickness of the substrate is usually 5 µm to 300 µm, preferably 10 µm to 200 µm, and more preferably 10 to 50 µm. In addition, since it is possible to apply only the optically anisotropic layer of the present invention by peeling off the substrate and transferring the polymer of the polymerizable liquid crystal compound containing the dichroic dye, an additional thin film effect is obtained.

<Alignment film>

In this specification, the alignment film has an alignment-regulating power that aligns the liquid crystal of a polymerizable liquid crystal compound in a desired direction.

The alignment film facilitates the alignment of the liquid crystal of the polymerizable liquid crystal compound. The state of the liquid crystal alignment, such as horizontal alignment, vertical alignment, hybrid alignment, and inclined alignment, varies depending on the properties of the alignment film and the polymerizable liquid crystal compound, and the combination thereof can be arbitrarily selected. For example, if the alignment film is a material that exhibits horizontal alignment as an alignment control force, the polymerizable liquid crystal compound can form horizontal alignment or hybrid alignment, and if it is a material that exhibits vertical alignment, the polymerizable liquid crystal compound can form vertical alignment or inclined alignment. The expressions horizontal, vertical, etc. indicate the direction of the major axis of the aligned polymerizable liquid crystal compound with respect to the optical anisotropic layer plane. For example, vertical alignment means that the major axis of the aligned polymerizable liquid crystal compound is perpendicular to the optical anisotropic layer plane. Perpendicular as used herein means 90° ± 20° with respect to the optical anisotropic layer plane.

The orientation regulation force can be arbitrarily adjusted according to the surface state or rubbing conditions when the alignment film is formed of an orientation polymer, and can be arbitrarily adjusted according to polarization irradiation conditions, etc. when formed of a photo-orientable polymer. In addition, the liquid crystal alignment can also be controlled by selecting the physical properties of the polymerizable liquid crystal compound, such as surface tension or liquid crystallinity.

As the alignment film formed between the substrate and the optically anisotropic layer, it is preferable that it is insoluble in the solvent used when forming the optically anisotropic layer on the alignment film, and further has heat resistance in the removal of the solvent or in the heat treatment for alignment of the liquid crystal. Examples of the alignment film include an alignment film made of an alignment polymer, a photoalignment film, a groove alignment film, a stretched film stretched in the alignment direction, and the like. When applied to a long roll film, a photoalignment film is preferable because the alignment direction can be easily controlled.

The thickness of the alignment film is usually in the range of 10 nm to 5000 nm, preferably in the range of 10 nm to 1000 nm, and more preferably in the range of 30 to 300 nm.

As the orientation polymer used in the rubbing alignment film, there may be mentioned polyamides or gelatins having an amide bond in the molecule, polyimides having an imide bond in the molecule, and their hydrolyzates such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Of these, polyvinyl alcohol is preferable. These orientation polymers may be used alone, or two or more may be used in combination.

As a method of rubbing, an example is a method of bringing a film of an orientation polymer formed on the surface of a substrate into contact by applying an orientation polymer composition to a substrate and annealing it on a rotating rubbing roll wrapped with a rubbing cloth.

The photo-alignment film is made of a polymer, oligomer, or monomer having a photo-reactive group. The photo-alignment film obtains alignment control power by irradiating polarized light. The photo-alignment film is more preferable in that the direction of the alignment control power can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

A photoreactive group refers to a group that causes liquid crystal alignment ability by irradiating light. Specifically, it is a group that causes a photoreaction that becomes the origin of liquid crystal alignment ability, such as molecular alignment induction, isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction caused by irradiating light. Among the above photoreactive groups, those that cause a dimerization reaction or photocrosslinking reaction are preferable in that they have excellent alignment properties. As a photoreactive group that can cause the above reaction, those having an unsaturated bond, particularly a double bond, are preferable, and a group having at least one selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond) is more preferable.

Examples of the photoreactive group having a C=C bond include a vinyl group, a polyene group, a stilbene group, a stilbazole group, a stilbazolium group, a chalcone group, and a cinnamoyl group. From the viewpoints of easy control of reactivity and expression of orientation regulation power during photoalignment, a chalcone group and a cinnamoyl group are preferable. Examples of the photoreactive group having a C=N bond include groups having structures such as an aromatic Schiff base group and an aromatic hydrazone. Examples of the photoreactive group having an N=N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and the like, as well as those having azoxybenzene as a basic structure. Examples of the photoreactive group having a C=O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, and a halogenated alkyl group.

In order to investigate polarization, it may be a form in which polarization is irradiated directly from the film surface, or a form in which polarization is irradiated from the substrate side and the polarization is transmitted and irradiated. In addition, it is particularly preferable that the polarization is substantially parallel light. It is preferable that the wavelength of the polarization to be irradiated is a wavelength range in which the photoreactive group of the polymer or monomer having the photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) in the range of a wavelength of 250 to 400 nm is particularly preferable. As a light source used for the polarization irradiation, a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an ultraviolet laser such as KrF or ArF, and a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp are more preferable. These lamps are preferable because the emission intensity of ultraviolet light having a wavelength of 313 nm is large. Polarization can be irradiated by irradiating light from the light source through an appropriate polarizer. As such polarizers, polarizing filters, polarizing prisms such as Glen Thompson or Glen Taylor, or wire grid type polarizers can be used.

<Composition for forming an optical anisotropic layer>

The composition for forming a polarizing film or the composition for forming a phase contrast film (hereinafter also referred to as the composition for forming an optically anisotropic layer) may also contain a reactive additive such as a solvent, a leveling agent, a polymerization initiator, a photosensitizer, a polymerization inhibitor, a crosslinking agent, or an adhesive, and it is preferable from the viewpoint of processability to contain a solvent or a leveling agent.

<Solvent>

The composition for forming an optically anisotropic layer may contain a solvent. Since polymerizable liquid crystal compounds generally have high viscosity, the composition for forming an optically anisotropic layer is often dissolved in a solvent, thereby facilitating application and, as a result, facilitating formation of an optically anisotropic layer. The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound, and is also preferably a solvent that is inactive to the polymerization reaction of the polymerizable liquid crystal compound.

Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene, nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; Examples thereof include amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. These solvents may be used alone, or two or more types may be used in combination.

The content of the solvent is preferably 50 to 98 mass% with respect to the total amount of the optically anisotropic layer-forming composition. In other words, the content of the solid content in the optically anisotropic layer-forming composition is preferably 2 to 50 mass%, and more preferably 5 to 30 mass%. When the content of the solid content is 50 mass% or less, the viscosity of the optically anisotropic layer-forming composition is lowered, so that the thickness of the optically anisotropic layer becomes approximately uniform, and thus it tends to be difficult for unevenness to occur in the optically anisotropic layer. In addition, the content of the solid content can be determined in consideration of the thickness of the optically anisotropic layer to be manufactured.

<Leveling agent>

The composition for forming an optical anisotropic layer may contain a leveling agent. A leveling agent is an additive that has the function of adjusting the fluidity of the composition and making the film obtained by applying the composition more flat. Examples of leveling agents include organic modified silicone oil-based, polyacrylate-based, and perfluoroalkyl-based leveling agents. Among them, polyacrylate-based leveling agents and perfluoroalkyl-based leveling agents are preferable.

When the composition for forming an optical anisotropic layer contains a leveling agent, it is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal compound, and further, the optical anisotropic layer obtained tends to be smoother. When the content of the leveling agent with respect to the polymerizable liquid crystal compound exceeds the above range, the optical anisotropic layer obtained tends to be uneven. In addition, the composition for forming an optical anisotropic layer may contain two or more types of leveling agents.

<Polymerization initiator>

The composition for forming an optical anisotropic layer may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound or the like. As the polymerization initiator, a photopolymerization initiator that generates active radicals by the action of light is preferable from the viewpoint of not depending on the phase state of the thermotropic liquid crystal.

As the photopolymerization initiator, any known photopolymerization initiator can be used as long as it is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound. Specifically, a photopolymerization initiator capable of generating an active radical or an acid by the action of light can be mentioned, and among these, a photopolymerization initiator that generates a radical by the action of light is preferable. The photopolymerization initiator can be used alone or in combination of two or more types.

As the photopolymerization initiator, a known photopolymerization initiator can be used, and for example, as the photopolymerization initiator generating an active radical, a self-cleavage type benzoin compound, acetophenone compound, hydroxyacetophenone compound, α-aminoacetophenone compound, oxime ester compound, acylphosphine oxide compound, azo compound, etc. can be used, and a hydrogen-abstraction type benzophenone compound, alkylphenone compound, benzoin ether compound, benzyl ketal compound, dibenzosvelone compound, anthraquinone compound, xanthone compound, thioxanthone compound, halogenoacetophenone compound, dialkoxyacetophenone compound, halogenobisimidazole compound, halogenotriazine compound, triazine compound, etc. can be used. As a photopolymerization initiator that generates acid, iodonium salts, sulfonium salts, etc. can be used. From the viewpoint of excellent reaction efficiency at low temperatures, a self-cleavage type photopolymerization initiator is preferable, and in particular, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are preferable.

The content of the polymerization initiator in the composition for forming an optical anisotropic layer can be appropriately adjusted depending on the type and amount of the polymerizable liquid crystal compound, but is usually 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the above range, polymerization can be performed without disturbing the orientation of the polymerizable liquid crystal compound.

<Increaser>

The composition for forming an optical anisotropic layer may contain a sensitizer. As the sensitizer, a photosensitizer is preferable. As the sensitizer, examples thereof include xanthone compounds such as xanthone and thioxanthone (for example, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and anthracene containing an alkoxy group (for example, dibutoxyanthracene, etc.); phenothiazine, and rubrene.

When the composition for forming an optical anisotropic layer contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the composition for forming an optical anisotropic layer can be further promoted. The amount of such sensitizer to be used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the content of the polymerizable liquid crystal compound.

[Polymerization inhibitor]

From the viewpoint of stably proceeding with the polymerization reaction, the composition for forming an optically anisotropic layer may contain a polymerization inhibitor. The progress of the polymerization reaction of the polymerizable liquid crystal compound can be controlled by the polymerization inhibitor.

Examples of the polymerization inhibitor include radical scavengers such as hydroquinone, alkoxy group-containing hydroquinone, alkoxy group-containing catechol (e.g., butylcatechol, etc.), pyrogallol, 2,2,6,6-tetramethyl-1-piperidinyloxy radical; thiophenols; β-naphthylamines and β-naphthols.

When the composition for forming an optical anisotropic layer contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the content of the polymerizable liquid crystal compound. When the content of the polymerization inhibitor is within the above range, polymerization can be performed without disturbing the orientation of the polymerizable liquid crystal compound.

<Composition for forming an optically anisotropic layer; reactive additive>

The composition for forming an optical anisotropic layer may contain a reactive additive. As the reactive additive, it is preferable that it has a carbon-carbon unsaturated bond or an active hydrogen reactive group in its molecule. In addition, the "active hydrogen reactive group" as used herein means a group that is reactive toward a group having an active hydrogen such as a carboxyl group (-COOH), a hydroxyl group (-OH), an amino group (-NH ₂ ), and representative examples thereof include a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, a thioisocyanate group, a maleic anhydride group, and the like. The number of carbon-carbon unsaturated bonds and active hydrogen reactive groups that the reactive additive has is usually 1 to 20 each, and preferably 1 to 10 each.

The carbon-carbon unsaturated bond of the reactive additive may be a carbon-carbon double bond, a carbon-carbon triple bond, or a combination thereof, but is preferably a carbon-carbon double bond. Among these, the reactive additive is preferably one containing a carbon-carbon unsaturated bond as a vinyl group and/or a (meth)acrylic group. Furthermore, a reactive additive having at least one active hydrogen reactive group selected from the group consisting of an epoxy group, a glycidyl group, and an isocyanate group is preferable, and a reactive additive having an acrylic group and an isocyanate group is more preferable.

Since light emitted from an OLED has polarization, when observing light emitted from the OLED through the second phase difference plate, the polarizer, and the first phase difference plate through sunglasses, it is preferable that the signs of the angle θ2 of the slow axis of the first layer of the second phase difference plate (the phase difference layer closest to the polarizer) with respect to the absorption axis of the polarizer and the signs of the angle θ1 of the slow axis of the first phase difference plate with respect to the absorption axis of the polarizer be different from each other, from the viewpoint of reducing coloration of the light observed through sunglasses. With this arrangement, the absorption axis of the first phase difference plate and the absorption axis of the phase difference layer (the first layer) closest to the polarizer among the phase difference layers constituting the second phase difference plate are arranged inverted with respect to the absorption axis of the polarizer as the axis, so the phase difference is canceled, and coloration of the observed light is reduced.

The absolute value of the angle of the slow axis of the first layer of the second phase difference plate (the slow axis layer closest to the polarizer) with respect to the absorption axis of the polarizer is preferably small, that is, the absorption axis and the slow axis are close to parallel, from the viewpoint of reducing the reflectivity when viewed in the diagonal direction. For this reason, the angle of the slow axis of the first layer of the second phase difference plate (the slow axis layer closest to the polarizer) with respect to the absorption axis of the polarizer is preferably 10° to 20°, or -10° to -20°. With respect to the second phase difference, in the case of a configuration that combines the above-mentioned orthogonal-dispersive λ/2 layer and the orthogonal-dispersive λ/4 layer, the first layer may be either a orthogonal-dispersive λ/2 layer or a orthogonal-dispersive λ/4 layer.

[First bonding layer, second bonding layer, third bonding layer, adhesive layer]

The first bonding layer (13), the second bonding layer (15), and the third bonding layer (17) in the optical laminate (1) are layers that are responsible for bonding two layers within the optical laminate (1), and an adhesive layer or an adhesive layer can be used.

<Adhesive layer>

The adhesive layer is one form of the first bonding layer (13), the second bonding layer (15), the third bonding layer (17), and the adhesive layer (19). In addition to these layers, the adhesive layer can be used as a bonding layer of two layers. As the adhesive composition forming the adhesive layer, any conventionally known adhesive composition having excellent optical transparency can be used without particular limitation, and for example, an adhesive composition having a base polymer such as an acrylic resin, a urethane resin, a silicone resin, or a polyvinyl ether resin can be used. Furthermore, an active energy ray-curable adhesive composition, a heat-curable adhesive composition, or the like may be used. Among these, an adhesive composition using an acrylic resin having excellent transparency, adhesive strength, re-peelability, weather resistance, heat resistance, and the like as a base polymer is preferable.

The adhesive composition may further contain a crosslinking agent, a silane compound, an antistatic agent, etc.

[(Meta)Acrylic Resin]

The (meth)acrylic resin included in the adhesive composition is preferably a polymer (hereinafter also referred to as a “(meth)acrylic acid ester polymer”) containing a structural unit derived from a (meth)acrylic acid alkyl ester represented by the following formula (X) (hereinafter also referred to as “structural unit (X)”) as a main component (for example, containing 50 parts by mass or more with respect to 100 parts by mass of the structural unit of the (meth)acrylic resin).

Also, in this specification, (meth)acrylic resin means either an acrylic resin or a methacrylic resin, and the word "(meth)" in (meth)acrylate has the same meaning.

[In the formula, R ¹⁰ represents a hydrogen atom or a methyl group, R ²⁰ represents an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have any structure of a straight chain, branched or cyclic structure, and the hydrogen atom of the alkyl group may be substituted with an alkoxy group having 1 to 10 carbon atoms.]

As the (meth)acrylic acid ester represented by the formula (X), for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, i-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, i-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n- and i-nonyl (meth)acrylate, n-decyl (meth)acrylate, i-decyl (meth)acrylate, Examples thereof include n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, and t-butyl (meth)acrylate. Specific examples of the alkoxy group-containing alkyl acrylate include 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and the like. Among these, those containing n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate are preferable, and those containing n-butyl (meth)acrylate are particularly preferable.

The (meth)acrylic acid ester polymer may contain a structural unit derived from a monomer other than the structural unit (X). The structural units derived from other monomers may be one type or two or more types. Examples of other monomers that the (meth)acrylic acid ester polymer may contain include a monomer having a polar functional group, a monomer having an aromatic group, and an acrylamide-based monomer.

As a monomer having a polar functional group, a (meth)acrylate having a polar functional group can be mentioned. As a polar functional group, a hydroxyl group; a carboxyl group; a substituted or unsubstituted amino group substituted with an alkyl group having 1 to 6 carbon atoms; a heterocyclic group such as an epoxy group can be mentioned.

The content of a structural unit derived from a monomer having a polar functional group in the (meth)acrylic acid ester polymer is preferably 10 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, further preferably 0.5 parts by mass or more and 5 parts by mass or less, and particularly preferably 1 part by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the total structural units of the (meth)acrylic acid ester polymer.

As a monomer having an aromatic group, there may be mentioned a (meth)acrylic acid ester having one (meth)acryloyl group and one or more aromatic rings (e.g., a benzene ring, a naphthalene ring, etc.) in the molecule, and having a phenyl group, phenoxyethyl group, or benzyl group. By including these structural units, the white fading phenomenon of a polarizing plate that occurs in a high temperature, high humidity environment can be suppressed.

The content of a structural unit derived from a monomer having an aromatic group in the (meth)acrylic acid ester polymer is preferably 20 parts by mass or less, more preferably 4 parts by mass or more and 20 parts by mass or less, and even more preferably 4 parts by mass or more and 15 parts by mass or less, with respect to 100 parts by mass of the total structural units of the (meth)acrylic acid ester polymer.

Examples of acrylamide monomers include N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, and N-(2-methylpropoxymethyl)acrylamide. By including these structural units, the bleed out of additives such as the antistatic agent described below can be suppressed.

In addition, as a structural unit derived from a monomer other than the structural unit (X), a structural unit derived from a styrene-based monomer, a structural unit derived from a vinyl-based monomer, a structural unit derived from a monomer having multiple (meth)acryloyl groups in the molecule, etc. may be included.

The weight average molecular weight (hereinafter also simply referred to as "Mw") of the (meth)acrylic resin (X) is preferably 500,000 to 2.5 million. When the weight average molecular weight is 500,000 or more, the durability of the first adhesive layer in a high temperature and high humidity environment can be improved. When the weight average molecular weight is 2.5 million or less, the operability when coating a coating solution containing the adhesive composition becomes good. The molecular weight distribution (Mw/Mn) expressed by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (hereinafter also simply referred to as "Mn") is usually 2 to 10. The "weight average molecular weight" and the "number average molecular weight" in this specification are polystyrene conversion values measured by the gel permeation chromatography (GPC) method.

The (meth)acrylic resin, when dissolved in ethyl acetate to make a 20 mass% solution, preferably has a viscosity at 25°C of 20 Pa·s or less, more preferably 0.1 to 15 Pa·s. When the viscosity of the (meth)acrylic resin at 25°C is within the above range, it contributes to improved durability and reworkability of a polarizing plate including an adhesive layer formed by the resin. The above viscosity can be measured by a Brookfield viscometer.

The glass transition temperature (Tg) of the (meth)acrylic resin is, for example, -60 to 20°C, preferably -50 to 15°C, more preferably -45 to 10°C, and even more preferably -40 to 0°C. In addition, the glass transition temperature can be measured by differential scanning calorimetry (DSC).

The (meth)acrylic resin may contain two or more types of (meth)acrylic acid ester polymers. Examples of such (meth)acrylic acid ester polymers include relatively low-molecular-weight (meth)acrylic acid ester polymers having a structural unit (X) derived from the (meth)acrylic acid ester as a main component and having a weight-average molecular weight in the range of 50,000 to 300,000.

(Meth)acrylic resins can usually be produced by known polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In the production of (meth)acrylic resins, polymerization is usually carried out in the presence of a polymerization initiator. The amount of the polymerization initiator to be used is usually 0.001 to 5 parts by mass relative to 100 parts by mass of the total of all monomers constituting the (meth)acrylic resin. (Meth)acrylic resins can also be produced by a method of polymerizing using active energy rays such as ultraviolet rays.

<Bridge>

The adhesive composition preferably contains a crosslinking agent. Examples of the crosslinking agent include commonly used crosslinking agents (e.g., isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, peroxides, etc.), and in particular, from the viewpoints of the pot life of the adhesive composition, crosslinking speed, and durability of the polarizing plate, an isocyanate-based compound is preferable.

An isocyanate compound is a compound having at least two isocyanato groups (-NCO) in the molecule. Specific examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. In addition, adducts obtained by reacting these isocyanate compounds with polyols such as glycerol or trimethylolpropane, and dimers or trimers of these isocyanate compounds may also be mentioned. Two or more types of isocyanate compounds may be combined.

The proportion of the crosslinking agent is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 1 part by mass, per 100 parts by mass of the (meth)acrylic resin.

<Silane compound>

The adhesive composition may further contain a silane compound.

Examples of the silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethoxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and the like.

Additionally, the silane compound may include an oligomer derived from the silane compound.

The content of the silane compound in the adhesive composition is usually 0.01 to 10 parts by mass, and preferably 0.05 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic resin. When the content of the silane compound is 0.01 parts by mass or more, the adhesion between the adhesive layer and the adherend tends to improve, and when the content is 10 parts by mass or less, the silane compound tends to be suppressed from bleeding out from the adhesive layer.

<Anti-Defense Agent>

The adhesive composition may further contain an antistatic agent. As the antistatic agent, known ones can be mentioned, and an ionic antistatic agent is preferable. As the cationic component constituting the ionic antistatic agent, organic cations and inorganic cations can be mentioned. As the organic cation, a pyridinium cation, an imidazolium cation, an ammonium cation, a sulfonium cation, a phosphonium cation, etc. can be mentioned. As the inorganic cation, alkali metal cations such as a lithium cation, a potassium cation, a sodium cation, a cesium cation, and the like, and alkaline earth metal cations such as a magnesium cation, a calcium cation, and the like can be mentioned. As the anionic component constituting the ionic antistatic agent, either an inorganic anion or an organic anion may be mentioned, but an anionic component containing a fluorine atom is preferable in that it has excellent antistatic performance. As anionic components containing fluorine atoms, examples thereof include hexafluorophosphate anion (PF ₆ ^- ), bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ^- ], and bis(fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N ^- ].

An ionic antistatic agent that is solid at room temperature is preferable in that it has excellent stability over time in the antistatic performance of the adhesive composition.

The content of the antistatic agent is, for example, 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, and more preferably 1 to 7 parts by mass, per 100 parts by mass of the (meth)acrylic resin.

The adhesive composition may contain additives such as an ultraviolet absorber, a solvent, a crosslinking catalyst, a tackifier, a plasticizer, and the like, alone or in combination of two or more. In addition, it is also useful to mix an ultraviolet-curable compound into the adhesive composition, form an adhesive layer, and then cure it by irradiating it with ultraviolet rays to form a harder adhesive layer.

The adhesive layer can be formed, for example, by dissolving or dispersing the adhesive composition in a solvent to form an adhesive composition containing a solvent, then applying this to the surface of a layer providing the adhesive layer, and drying it.

The thickness of the adhesive layer is usually 0.1 to 30 ㎛, preferably 3 to 30 ㎛, and more preferably 5 to 25 ㎛.

[Adhesive layer]

The adhesive layer is one form of the first bonding layer (13), the second bonding layer (15), and the third bonding layer (17). In addition to these layers, the adhesive layer can be used as a bonding layer of two layers. Examples of the adhesive composition include an aqueous adhesive composition, a curable adhesive composition that is cured by heating or irradiation with active energy rays such as ultraviolet rays, visible light, electron rays, and X-rays, and the like. Examples of the aqueous adhesive composition include one in which a polyvinyl alcohol-based resin or a urethane resin as a main component is dissolved in water, and one in which a polyvinyl alcohol-based resin or a urethane resin as a main component is dispersed in water. The aqueous adhesive composition may further contain a curable component such as a polyhydric aldehyde, a melamine-based compound, a zirconia compound, a zinc compound, a glyoxal compound, a water-soluble epoxy resin, or a crosslinking agent. Examples of the water-based adhesive composition include the adhesive composition described in Japanese Patent Application Laid-Open No. 2010-191389, the adhesive composition described in Japanese Patent Application Laid-Open No. 2011-107686, the composition described in Japanese Patent Application Laid-Open No. 2020-172088, and the composition described in Japanese Patent Application Laid-Open No. 2005-208456.

The curable adhesive composition is preferably an active energy ray-curable adhesive composition that contains a curable (polymerizable) compound as a main component and is cured by irradiation with active energy rays. Examples of the active energy ray-curable adhesive composition include a cationic polymerization adhesive composition that contains a cationic polymerizable compound as a curable compound, a radical polymerization adhesive composition that contains a radical polymerizable compound as a curable compound, and a hybrid adhesive composition that contains both a cationic polymerizable compound and a radical polymerizable compound as curable compounds.

A cationic polymerizable compound is a compound or oligomer that undergoes a cationic polymerization reaction and is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron rays, or X-rays, or by heating, and specific examples thereof include epoxy compounds, oxetane compounds, and vinyl compounds.

Examples of the epoxy compounds include alicyclic epoxy compounds (compounds having at least one epoxy group bonded to an alicyclic ring in the molecule) such as 3,4-epoxycyclohexylmethyl and 3,4-epoxycyclohexanecarboxylate; aromatic epoxy compounds (compounds having an aromatic ring and an epoxy group in the molecule) such as bisphenol A diglycidyl ether; and aliphatic epoxy compounds (compounds having at least one oxylane ring bonded to an aliphatic carbon atom in the molecule) such as 2-ethylhexyl glycidyl ether and 1,4-butanediol diglycidyl ether.

As oxetane compounds, compounds having one or more oxetane rings in the molecule, such as 3-ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, can be mentioned.

The cationic polymerization type adhesive composition preferably contains a cationic polymerization initiator. The cationic polymerization initiator may be a thermal cationic polymerization initiator or a photocationic polymerization initiator. Examples of the cationic polymerization initiator include aromatic diazonium salts such as benzenediazonium hexafluoroantimonate; aromatic iodonium salts such as diphenyliodonium tetrakis(pentafluorophenyl)borate; aromatic sulfonium salts such as triphenylsulfonium hexafluorophosphate; and iron-arene complexes such as xylene-cyclopentadienyl iron(II) hexafluoroantimonate. The content of the cationic polymerization initiator is usually 0.1 to 10 parts by mass per 100 parts by mass of the cationic polymerizable compound. Two or more types of cationic polymerization initiators may be contained.

Examples of the cationic polymerization adhesive composition include cationic polymerization compositions described in Japanese Patent Application Laid-Open No. 2016-126345, International Publication No. 2019/10315, and Japanese Patent Application Laid-Open No. 2021-113969.

A radical polymerizable compound is a compound or oligomer that undergoes a radical polymerization reaction and is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron rays, or X-rays, or by heating, and specifically, a compound having an ethylenically unsaturated bond can be mentioned. Examples of a compound having an ethylenically unsaturated bond include a (meth)acrylic compound having one or more (meth)acryloyl groups in the molecule, and a vinyl compound having one or more vinyl groups in the molecule.

As the (meth)acrylic compound, examples thereof include (meth)acryloyl group-containing compounds such as (meth)acrylic oligomers, which are obtained by reacting two or more types of (meth)acrylate monomers, (meth)acrylamide monomers, and functional group-containing compounds each having at least one (meth)acryloyloxy group in the molecule, and which have at least two (meth)acryloyl groups in the molecule.

The radical polymerization type adhesive composition preferably contains a radical polymerization initiator. The radical polymerization initiator may be a thermal radical polymerization initiator or a photoradical polymerization initiator. Examples of the radical polymerization initiator include acetophenone-based initiators such as acetophenone and 3-methylacetophenone; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone and 4,4'-diaminobenzophenone; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; xanthone, fluorenone and the like. The content of the radical polymerization initiator is usually 0.1 to 10 parts by mass with respect to 100 parts by mass of the radical polymerizable compound. Two or more types of radical polymerization initiators may be contained.

Examples of radical polymerization adhesive compositions include radical polymerization compositions described in Japanese Patent Application Laid-Open No. 2016-126345, Japanese Patent Application Laid-Open No. 2016-153474, and International Publication No. 2017/183335.

The active energy ray-curable adhesive composition may contain additives such as an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, an antistatic agent, a leveling agent, and a solvent, as needed.

Bonding of two layers by an adhesive layer can be carried out by coating an adhesive composition on at least one bonding surface selected from each of the two layers, overlapping the two surfaces with the coating layer of the adhesive composition interposed between them, applying pressure from above and below using a bonding roll or the like to bond them, and then drying the adhesive layer, curing it by irradiating it with an active energy ray, or curing it by heating.

Before forming the coating layer of the adhesive layer, at least one of the bonding surfaces selected from each of the two layers may be subjected to an adhesive treatment such as saponification treatment, corona treatment, plasma treatment, primer treatment, or anchor coating treatment.

To form the coating layer of the adhesive composition, various coating methods such as a die coater, a comma coater, a gravure coater, a wire bar coater, and a doctor blade coater can be used.

The light irradiation intensity when irradiating with active energy rays is determined depending on the composition of the active energy ray-curable adhesive composition and is not particularly limited, but is preferably 10 mW/cm2 or more and 1,000 mW/cm2 or less. In addition, the irradiation intensity is preferably an intensity in a wavelength range effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. It is preferable to irradiate once or multiple times with such light irradiation intensity so that the accumulated light dose is 10 mJ/cm2 or more, and more preferably 100 mJ/cm2 or more and 1,000 mJ/cm2 or less.

The light source used to perform polymerization and curing of the active energy ray-curable adhesive composition is not particularly limited, and examples thereof include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The thickness of the adhesive layer formed by the water-based adhesive composition may be, for example, 5 ㎛ or less, preferably 1 ㎛ or less, more preferably 0.5 ㎛ or less, and may be 0.01 ㎛ or more, and preferably 0.05 ㎛ or more.

The thickness of the adhesive layer formed by the active energy ray-curable adhesive composition may be, for example, 10 µm or less, preferably 5 µm or less, more preferably 3 µm or less, may be 0.1 µm or more, preferably 0.5 µm or more, and more preferably 1 µm or more.

[Other layers that the optical laminate may have]

It is preferable that the optical laminate has a layer having a predetermined ultraviolet absorption characteristic. The predetermined ultraviolet absorption characteristic is a characteristic that satisfies the relationships of the following equations (5), (6), and (7), where Tr(λ) is the transmittance of light having a wavelength of λ nm.

Tr(450) ≥ 85% (5)

30% ≤ Tr(420) ≤ 75% (6)

0% ≤ Tr(400) ≤ 10% (7)

By providing a layer having a predetermined ultraviolet absorption characteristic, coloring of transmitted light can be suppressed.

A layer having a predetermined ultraviolet absorption characteristic may be provided at any position in the optical laminate, and for example, the surface treatment layer provided on the surface of the viewer side of the first protective film may have a configuration satisfying the above formulas (5), (6), and (7).

A type of layer having desirable UV absorption characteristics to satisfy the above equations (5), (6), and (7) is described.

According to one embodiment, the layer having a predetermined ultraviolet absorbing property includes an ultraviolet absorbent. For example, the following formula (XI):

A compound (XI) represented by is included as an ultraviolet absorber.

In the above formula (XI), A represents a methylene group, a secondary amino group, an oxygen atom or a sulfur atom. From the viewpoint of exhibiting high photoselective absorption, A preferably represents a methylene group, a secondary amino group or an oxygen atom.

In the above formula (XI), R ¹ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

R ¹ represents an alkyl group having preferably 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 3 carbon atoms, from the viewpoint of exhibiting high photoselective absorption. Here, when the alkyl group has at least one methylene group, at least one of the methylene groups may be substituted with an oxygen atom or a sulfur atom. Examples of such alkyl groups include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, an n-hexyl group, an n-octyl group, an n-decyl group, a methoxy group, an ethoxy group, and an isopropoxy group.

In the above formula (XI), R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. From the viewpoint of exhibiting high light-selective absorption, R ² and R ³ each independently represent preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, even more preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and particularly preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

In the above formula (XI), R ⁴ represents an alkyl group having 3 to 50 carbon atoms, or an alkyl group having 3 to 50 carbon atoms and having at least one methylene group, wherein at least one of the methylene groups is substituted with an oxygen atom.

The alkyl group having 3 to 50 carbon atoms in R ⁴ preferably has 8 to 45 carbon atoms (e.g., 10 to 45), more preferably 12 to 40, still more preferably 13 to 35, and particularly preferably 14 to 30, from the viewpoints of affinity for hydrophobic substances, solubility in hydrophobic solvents, and economical manufacturing efficiency. In addition, a substituent may be bonded to a carbon atom on the alkyl group.

The alkyl group having 3 to 50 carbon atoms and having at least one methylene group in R ⁴ is, from the viewpoints of affinity for hydrophobic substances, solubility in hydrophobic solvents, and economical manufacturing, an alkyl group having preferably 3 to 40 carbon atoms, more preferably 4 to 35 carbon atoms, and particularly preferably 5 to 30 carbon atoms. Here, in the alkyl group having 3 to 50 carbon atoms and having at least one methylene group, at least one of the methylene groups is substituted with an oxygen atom, and examples thereof include an ethoxy group, a propoxy group, and a 2-methoxyethoxymethyl group. Furthermore, polyethylene glycol groups such as a diethylene glycol group and a triethylene glycol group, and polypropylene glycol such as a dipropylene glycol group and a tripropylene glycol group, etc. can also be mentioned.

In addition, a substituent may be bonded to the carbon atom on the alkyl group of R ⁴ . Examples of the substituent include a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 6 carbon atoms, an alkylsulfonyl group having 1 to 6 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, an N-alkylamino group having 1 to 6 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 6 carbon atoms, and an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

When R ⁴ is an alkyl group having 3 to 50 carbon atoms, from the viewpoints of affinity with a hydrophobic substance and solubility in a hydrophobic solvent, it is more preferable that R ⁴ is an alkyl group having a branched structure having 3 to 12 carbon atoms, and it is even more preferable that it is an alkyl group having a branched structure having 6 to 10 carbon atoms.

Here, an alkyl group having a branched structure refers to an alkyl group in which at least one of the carbon atoms of the alkyl group is a tertiary carbon or a quaternary carbon. Specific examples of alkyl groups having a branched structure having 3 to 12 carbon atoms include alkyl groups having the following structure.

* Indicates a connection.

In the above formula (XI), X ¹ represents an electron-withdrawing group. From the viewpoint of improving the photoselective absorption, X ¹ is preferably -NO ₂ , -CN, -COR ⁸ , -COOR ⁹ , -OR ¹⁰ , a halogen atom (-F, -Cl, -Br, -I), -CSR ¹¹ , -CSOR ¹² , or -CSNR ¹³ , more preferably a nitro group, a cyano group, or -COOR ⁹ , and even more preferably a cyano group, or -COOR ⁹ . Here, R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, for example, 2 to 5 carbon atoms, or a phenyl group.

In the above formula (XI), Y ¹ represents -CO-, -COO-, -OCO-, -O-, -S-, -NR ⁵ -, -NR ⁶ CO-, -CONR ⁷ -, or -CS-, and from the viewpoint of improving photoselective absorption, preferably represents -CO-, -COO-, -OCO-, or -O-, and more preferably represents -CO-, -COO-, or -OCO-. Here, R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, for example, 2 to 5 carbon atoms, or a phenyl group.

In a preferred embodiment of the present invention, the compound (XI) represented by the formula (XI) is represented by the following formula (XI-I):

It is preferable to be expressed as , from the viewpoint of excellent solubility in various solvents and/or affinity with various compounds.

In the above formula (XI-I), R ^4-1 represents an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 2 to 5 carbon atoms, more preferably an alkyl group having 3 to 4 carbon atoms.

n is an integer from 1 to 10, preferably an integer from 1 to 8, more preferably an integer from 1 to 6, for example, an integer from 1 to 4, and particularly an integer from 1 to 3, from the viewpoint of excellent solubility in various solvents and/or affinity with various compounds. In addition, when n is within the above range, the light absorbency per 1 mass part is improved, and even if the compound (XI) included in a member constituting the optical laminate is a small amount, the blue light cut function can be exhibited, and further, for example, when the compound (XI) is contained in an adhesive, the adhesive function thereof is unlikely to be inhibited, and further, when the compound (XI) is contained in a protective film, the optical function as a protective film is unlikely to be inhibited.

A, R ¹ , R ² and R ³ are the same as in the above formula (XI).

In a more preferred embodiment of the present invention, the compound represented by the formula (XI-I) is represented by the following formula (XI-II):

It is more preferable to represent it as. If the compound represented by the above formula (XI-I) is a compound represented by the above formula (XI-II), since the solubility in various solvents and/or affinity with various compounds is excellent, it becomes easy to uniformly dissolve the compound in the solvent, and at the same time, since the affinity with various compounds is excellent and exhibits amphiphilicity, when the compound is included in a member constituting an optical laminate, it is difficult to cause bleed out, so that a light absorption function can be stably exhibited.

In formula (XI-II), R ^4-1 and n are the same as in formula (XI-I).

[Video display device]

The image display device includes an optical laminate and an image display element (such as an organic EL display element). The optical laminate is arranged on the viewing side of the image display element. The optical laminate (1) can be bonded to the image display element using an adhesive layer (19).

The image display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, an electroluminescence display device, and the like.

The image display device can be used as a mobile device such as a smartphone or tablet, a television, a digital photo frame, an electronic signboard, a measuring instrument or gauge, an office device, a medical device, a computer device, etc.

[Example]

Hereinafter, the present invention will be described more specifically by showing examples and comparative examples, but the present invention is not limited by these examples. The mixing amounts indicated by "%" and "part" in the examples and comparative examples are mass% and mass parts, unless otherwise specified.

[Fabrication of optical laminates]

Optical laminates of examples and comparative examples having the configurations shown in Fig. 1 were produced. Among the configurations shown in Fig. 1, the first protective film with a surface treatment layer attached (a laminate of the surface treatment layer (11) and the first protective film (12)) and the second phase difference plate (18) were selected and employed for each example and each comparative example, and the other components, that is, the first bonding layer (13), the polarizer (14), the second bonding layer (15), the second protective film (16), the third bonding layer (17), and the adhesive layer (19), were the same for all examples and comparative examples.

[Measurement of phase difference value]

The phase difference values of the first protective film and the second phase difference plate were measured using a phase difference measuring device (KOBRA-WPR manufactured by Oji Scientific Instruments).

[Measurement of transmittance]

The transmittance of the surface treatment layer of the first protective film with the surface treatment layer attached was measured by cutting the first protective film with the surface treatment layer attached to a size of 30 mm × 30 mm and using an ultraviolet-visible spectrophotometer “UV-2450” manufactured by Shimadzu Corporation, at a wavelength of 200 to 800 nm, to measure the transmittance [%).

[1] 1st protective film

As the first protective film, the following first protective films 1a to 5a were prepared.

(1) 1st protective film 1a

A cycloolefin film (manufactured by Zeon Corporation, trade name "ZF-14", glass transition temperature 140°C) was prepared. The prepared film was uniaxially stretched at 140°C, and the stretching ratio was adjusted so as to obtain the following retardation values, thereby obtaining a first protective film 1a. The obtained stretched film had retardation values of Re1 (450) = 105 nm and Re1 (550) = 100 nm, and had a slow axis in the stretching direction.

(2) 1st protective film 2a

The stretching conditions for obtaining the stretched film of the first protective film 1a were changed to adjust the following phase difference values to obtain the first protective film 2a. The obtained stretched film had phase difference values of Re1 (450) = 127 nm and Re1 (550) = 121 nm, and had a slow axis in the stretching direction.

(3) 1st protective film 3a

The stretching conditions for obtaining the stretched film of the first protective film 1a were changed to adjust the phase difference values below to obtain the first protective film 4a. The obtained stretched film had phase difference values of Re1 (450) = 147 nm and Re1 (550) = 140 nm, and had a ground axis in the stretching direction.

(4) 1st protective film 4a

A cycloolefin film (manufactured by Zeon Corporation, product name "ZF-14") was prepared. After adjusting the ratio of the polymerizable liquid crystal compound described in Japanese Patent Application Laid-Open No. 2015-163935 to have the following phase difference values, the polymerizable liquid crystal compound was applied onto the prepared cycloolefin film, and the phase difference film was formed by polymerizing the polymerizable liquid crystal compound, thereby obtaining a first protective film 5a. The phase difference values of the obtained first protective film 5a were Re1 (450) = 119 nm and Re1 (550) = 140 nm.

(5) 1st protective film 5a

A cycloolefin film (manufactured by Zeon Corporation, product name "ZF-14") was prepared. This film was used as the first protective film. The first protective film had a phase difference value of Re1 (450) = 0 nm and Re1 (550) = 0 nm.

[2] Surface treatment layer attached to the first protective film

On the first protective film obtained above, a surface treatment layer was formed using the surface treatment layer composition below, and a first protective film with a surface treatment layer attached was obtained. The combination and evaluation results are shown in Table 3. The first protective film with a surface treatment layer attached was cut so that the ground axis was 45° or -45° with respect to the longitudinal direction of the rectangle, and used in an optical laminate.

(Surface treatment layer composition A)

As a surface treatment layer composition A, 20 parts of EBECRYL4858 (manufactured by DAICL-ALLNEX LTD.), 0.21 part of Irgacure-184 (manufactured by BASF Japan Ltd.), 26 parts of cyclopentanone (manufactured by Kanto Chemical Co., Inc.), and 24 parts of N-methyl-2-pyrrolidone (manufactured by Kanto Chemical Co., Inc.) were mixed and stirred at room temperature for 2 hours to obtain a homogeneous solution, which was then used.

(Formation of surface treatment layer)

On the first protective film, the surface treatment layer composition A was applied using a wire bar so that the film thickness after curing became 5 ㎛ to form a coating film. For the formed coating film, the solvent was evaporated by flowing dry air of 70℃ at a flow rate of 0.5 m/s for 30 seconds, and ultraviolet rays were irradiated in a nitrogen atmosphere (oxygen concentration 200 ppm or less) so that the accumulated light amount became 200 mJ/cm2 to cure, thereby forming a surface treatment layer. The surface treatment layer had a transmittance Tr(450) of 100% for light having a wavelength of 450 nm, a transmittance Tr(420) of 100% for light having a wavelength of 420 nm, and a transmittance Tr(400) of 100% for light having a wavelength of 400 nm.

(Surface treatment layer composition B)

As a surface treatment layer composition B, 20 parts of EBECRYL4858 (manufactured by DAICL-ALLNEX LTD.), 0.80 parts of UVA-01 synthesized in Synthesis Example 1, 0.21 parts of Irgacure-184 (manufactured by BASF Japan Ltd.), 26 parts of cyclopentanone (manufactured by Kanto Chemical Co., Inc.), and 24 parts of N-methyl-2-pyrrolidone (manufactured by Kanto Chemical Co., Inc.) were mixed and stirred at room temperature for 2 hours to obtain a homogeneous solution, which was then used.

(Synthesis Example 1)

A nitrogen atmosphere was created inside a 200 mL 4-necked flask equipped with a Dimroth condenser and a thermometer, and 10 g of powder of compound UVA-M-02 synthesized with reference to a patent document (Japanese Patent Application Laid-Open No. 2014-194508), 3.7 g of acetic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.), 5.8 g of 2-ethoxyethyl cyanoacetate (manufactured by TOKYO KASEI KOGYO CO., LTD.), and 60 g of acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) were charged and stirred with a magnetic stirrer. At an internal temperature of 25°C, 4.7 g of N,N-diisopropylethylamine (hereinafter abbreviated as DIPEA; manufactured by TOKYO KASEI KOGYO CO., LTD.) was added dropwise from a dropping funnel over 1 hour, and the mixture was kept at an internal temperature of 25°C for an additional 2 hours after completion of the dropping. After completion of the reaction, acetonitrile was removed using a reduced pressure evaporator, toluene was added to the obtained oily substance, and the produced insoluble components were removed by filtration. The filtrate was concentrated again using a reduced pressure evaporator, and the concentrated solution was purified by column chromatography (silica gel), and recrystallized from toluene to obtain the target product. The crystals were dried under reduced pressure at 60°C to obtain 5.2 g of compound UVA-01 as a yellow powder. The yield was 65%. In addition, the absorption maximum wavelength (λmax) was measured using a spectrophotometer UV-3150 (manufactured by Shimadzu Corporation). λmax=389 nm (in 2-butanone), ε(400) was 125 L/(g cm), and ε(420)/ε(400) was 0.0153.

And, when ^1H -NMR analysis was performed, the following peaks were observed, confirming that compound UVA-01 was produced.

¹ H-NMR(CDCl ₃ )δ: 1.21(t, 3H), 2.10(quIn, 2H), 2.98-3.04(m, 5H), 3.54-3.72(m, 6H), 4.31(t, 2H), 5.53 (d, 2H), 7.93(d, 2H)

(Formation of surface treatment layer)

On the first protective film, the surface treatment layer composition B was applied using a wire bar so that the film thickness after curing became 5 ㎛, thereby forming a coating film. For the formed coating film, the solvent was evaporated by circulating dry air of 70℃ at a flow rate of 0.5 m/s for 30 seconds, and the ultraviolet rays were irradiated in a nitrogen atmosphere (oxygen concentration 200 ppm or less) so that the accumulated light amount became 200 mJ/cm2, thereby forming a surface treatment layer. The surface treatment layer had a transmittance Tr(450) of 90% for light having a wavelength of 450 nm, a transmittance Tr(420) of 50% for light having a wavelength of 420 nm, and a transmittance Tr(400) of 0% for light having a wavelength of 400 nm.

(Surface treatment layer composition C)

As a composition C for a surface treatment layer, 20 parts of EBECRYL4858 (manufactured by DAICL-ALLNEX LTD.), 0.80 parts of UVA-02 represented by the following chemical formula (1-1-2), 0.21 parts of Irgacure-184 (manufactured by BASF Japan Ltd.), 26 parts of cyclopentanone (manufactured by Kanto Chemical Co., Inc.), and 24 parts of N-methyl-2-pyrrolidone (manufactured by Kanto Chemical Co., Inc.) were mixed and stirred at room temperature for 2 hours to obtain a homogeneous solution, which was then used.

(UVA-02)

(Formation of surface treatment layer)

On the first protective film, the surface treatment layer composition C was applied using a wire bar so that the film thickness after curing became 5 ㎛ to form a coating film. For the formed coating film, the solvent was evaporated by circulating dry air of 70℃ at a flow rate of 0.5 m/s for 30 seconds, and the ultraviolet rays were irradiated in a nitrogen atmosphere (oxygen concentration 200 ppm or less) so that the accumulated light amount became 200 mJ/cm2 to cure, thereby forming a surface treatment layer. The surface treatment layer had a transmittance Tr(450) of 49% for light having a wavelength of 450 nm, a transmittance Tr(420) of 18% for light having a wavelength of 420 nm, and a transmittance Tr(400) of 6% for light having a wavelength of 400 nm.

[3] Second phase plate

(2nd phase plate 1b)

<Production of 1st floor 1b>

[Preparation of photo-orientable polymer composition (1)]

A photoalignable material having the following structure (weight average molecular weight: 50,000, m:n=50:50) was manufactured according to the method described in Japanese Patent Application Laid-Open No. 2021-196514. Two parts of the photoalignable material and 98 parts of propylene glycol monomethyl ether (PGME, solvent) were mixed as components, and the resulting mixture was stirred at 80°C for 1 hour, thereby preparing a photoalignable polymer composition (1).

Photo-orientable materials:

[Production of polymerizable liquid crystal compounds]

A polymerizable liquid crystal compound (A1) and a polymerizable liquid crystal compound (A2) having the structures shown below were prepared, respectively. The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were prepared in the same manner as described in Japanese Patent Application Laid-Open No. 2010-244038.

Polymerizable liquid crystal compound (A1):

Polymerizable liquid crystal compound (A2):

[Preparation of composition (Y1) for forming a phase barrier film]

A polymerizable liquid crystal compound (A1) and a polymerizable liquid crystal compound (A2) were mixed at a mass ratio of 80:20 to obtain a mixture. Per 100 parts of the obtained mixture, 0.1 part of a leveling agent "MEGAFACE F-556" (manufactured by DIC Corporation), 2.5 parts of a photopolymerization initiator "Omnirad 907" (manufactured by IGM Resin B.V.), and 0.1 part of an ionic compound (B) were added. In addition, propylene glycol monomethyl ether acetate (PEGMEA) was added, and the mixture was stirred at a temperature of 80°C for 1 hour, thereby preparing a composition (Y1) for forming a phase contrast film. The ionic compound (B) has a structure represented by the following formula.

[Table 1]

Ionic compound (B)

A photoalignable polymer composition (1) was applied to a triacetyl cellulose film (TAC) (manufactured by KONICA MINOLTA, INC., KC4UY) cut into a rectangle. The obtained coating film was dried at 120°C for 2 minutes, and then cooled to room temperature to form a dry film. Furthermore, using a UV irradiation device, 100 mJ (based on 313 nm) of polarized ultraviolet light was continuously irradiated so as to be -15° with respect to the longitudinal direction of the TAC, to form a 100 nm photoalignment film. Thereon, a composition (Y1) for forming a phase contrast film was applied by a bar coater. The obtained coating film was dried at 100°C for 1 minute, and then cooled to room temperature to obtain a dry film. Next, by continuously irradiating the dried film with ultraviolet light at an exposure dose of 1000 mJ/cm2 (based on 365 nm) using a high-pressure mercury lamp in a nitrogen atmosphere, the polymerizable liquid crystal compound was cured in a state in which it was aligned horizontally with respect to the substrate plane. In this way, a first layer 1b composed of TAC/alignment film/(λ/2 layer) was obtained. The film thickness of the obtained λ/2 layer was measured with a laser microscope and was found to be 1.8 μm. The in-plane retardation value was measured using KOBRA-WR manufactured by Oji Scientific Instruments. As a result, the in-plane retardation value at a wavelength of 550 nm was Re(550)=270 nm, and the in-plane retardation value at a wavelength of 450 nm was Re(450)=291 nm. In addition, since the retardation value of TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties. The orientation angle was -15° with respect to the longitudinal direction of the TAC.

<Production of 2nd floor 1b>

Water was added to commercially available polyvinyl alcohol (polyvinyl alcohol 1000 fully saponified type, manufactured by Wako Pure Chemical Corporation). The mixture was heated at 100°C for 1 hour to obtain an oriented polymer composition.

A polymerizable liquid crystal compound, Paliocolor LC242 (manufactured by BASF Japan Ltd.), a leveling agent, "BYK-361N" (manufactured by BYK-Chemie Japan K.K.), and a photopolymerization initiator, "Omnirad 907" (manufactured by IGM Resin B.V.), were mixed in the amounts shown in Table 2 below. In addition, propylene glycol 1-monomethyl ether 2-acetate (PGME) was added. The mixture was stirred at 80°C for 1 hour, thereby preparing a composition (Y2) for forming a phase difference plate.

[Table 2]

Polymerizable liquid crystal compound LC242:

An orientation polymer composition was applied to a triacetyl cellulose film (TAC) (manufactured by KONICA MINOLTA, INC., KC4UY) cut into a rectangle. The coating was heated and dried to form an orientation polymer film having a thickness of 100 nm. The surface of the obtained orientation polymer film was rubbed at an angle of 75° from the longitudinal direction of the TAC to form an orientation film. A composition (Y2) for forming a phase difference plate was applied onto the orientation film by a bar coater. The obtained coating film was dried at 100°C for 1 minute and then cooled to room temperature to obtain a dry film. Next, using a high-pressure mercury lamp ("UniQure VB-15201BY-A" manufactured by Ushio Inc.), ultraviolet light at an exposure dose of 1000 mJ/cm2 (based on 365 nm) was irradiated to the dried film in a nitrogen atmosphere, and the polymerizable liquid crystal compound was cured in a state where it was aligned horizontally to the substrate plane. In this way, a second layer 1b composed of TAC/alignment film/(λ/4 layer) was obtained. The film thickness of the obtained λ/4 layer was measured with a laser microscope and was found to be 1.0 μm. The in-plane retardation value was measured using KOBRA-WR manufactured by Oji Scientific Instruments. As a result, the in-plane retardation value at a wavelength of 550 nm was Re(550)=142 nm, and the in-plane retardation value at a wavelength of 450 nm was Re(450)=153.4 nm. In addition, since the phase difference value at the wavelength of 550 nm of TAC is approximately 0, it does not affect the optical properties. The orientation angle was 75° with respect to the longitudinal direction of the TAC.

After corona treatment was performed on the phase difference film side of the substrate/alignment film/(λ/2 layer) as the first layer 1b and the substrate/alignment film/(λ/4 layer) as the second layer 1b, respectively, the respective substrates were bonded together with an adhesive layer (acrylic adhesive layer) interposed so that the longitudinal directions of the respective substrates become the same, thereby obtaining substrate/alignment film/(λ/2 layer)/adhesive layer/(λ/4 layer)/alignment film/substrate. For the second phase difference plate 1b, the apparent in-plane phase difference value Re2(550) at a wavelength of 550 nm was 139 nm, and the apparent in-plane phase difference value Re2(450) at a wavelength of 450 nm was 106 nm. In addition, since the phase difference value of TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties mentioned above. When viewed from the λ/2 layer side, the orientation angle was 15° for the λ/2 layer and 75° for the λ/4 layer with respect to the longitudinal direction of the TAC.

(2nd phase plate 2b)

<Production of 2b, 1st floor>

A first layer 3b was produced under the same conditions as the first layer 1b, except that the alignment direction of the photo-alignment film of the first layer 1b was 15° with respect to the longitudinal direction of the TAC. The film thickness of the obtained λ/2 layer was measured with a laser microscope, and it was 1.8 μm. The in-plane phase difference value was measured using KOBRA-WR manufactured by Oji Scientific Instruments. As a result, the in-plane phase difference value at a wavelength of 550 nm was Re(550)=270 nm, and the in-plane phase difference value at a wavelength of 450 nm was Re(450)=291 nm. In addition, since the phase difference value of the TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties. The alignment angle was 15° with respect to the longitudinal direction of the TAC.

<Production of 2nd floor 2b>

A second layer 2b was produced under the same conditions as the second layer 1b, except that the rubbing treatment angle of the second layer 1b was -75° with respect to the longitudinal direction of the TAC. The in-plane phase difference value at a wavelength of 550 nm was Re(550)=142 nm, and the in-plane phase difference value at a wavelength of 450 nm was Re(450)=153.4 nm. In addition, since the phase difference value of the TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties. The orientation angle was -75° with respect to the longitudinal direction of the TAC.

After corona treatment was performed on the phase difference film side of the substrate/alignment film/(λ/2 layer) as the first layer 2b and the substrate/alignment film/(λ/4 layer) as the second layer, respectively, the respective substrates were bonded together with an adhesive layer (acrylic adhesive layer) interposed so that the longitudinal directions of the respective substrates were in the same direction, thereby obtaining substrate/alignment film/(λ/2 layer)/adhesive layer/(λ/4 layer)/alignment film/substrate. For the second phase difference plate 2b, the apparent in-plane phase difference value Re2(550) at a wavelength of 550 nm was 139 nm, and the apparent in-plane phase difference value Re2(450) at a wavelength of 450 nm was 106 nm. In addition, since the phase difference value of TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties mentioned above. When viewed from the λ/2 layer side, the orientation angle was -15° for the λ/2 layer and -75° for the λ/4 layer with respect to the longitudinal direction of the TAC.

(2nd phase plate 3b)

<Production of 3b on the 1st floor>

A first layer 3b was produced under the same conditions as the first layer 1b, except that the alignment direction of the photo-alignment film of the first layer 1b was -75° with respect to the longitudinal direction of the TAC. The film thickness of the obtained λ/2 layer was measured with a laser microscope, and it was 1.8 μm. The in-plane retardation value was measured using KOBRA-WR manufactured by Oji Scientific Instruments. As a result, the in-plane retardation value at a wavelength of 550 nm was Re(550)=270 nm, and the in-plane retardation value at a wavelength of 450 nm was Re(450)=291 nm. In addition, since the retardation value at a wavelength of 550 nm of the TAC is approximately 0, it does not affect the optical properties described above. The alignment angle was -75° with respect to the longitudinal direction of the TAC.

<Production of 2nd floor 3b>

A second layer 3b was produced under the same conditions as the second layer 1b, except that the rubbing treatment angle of the second layer 1b was 15° with respect to the longitudinal direction of the TAC. The in-plane phase difference value at a wavelength of 550 nm was Re(550)=142 nm, and the in-plane phase difference value at a wavelength of 450 nm was Re(450)=153.4 nm. In addition, since the phase difference value of the TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties. The orientation angle was 15° with respect to the longitudinal direction of the TAC.

After corona treatment was performed on the phase difference film side of the substrate/alignment film/(λ/2 layer) as the first layer 3b and the substrate/alignment film/(λ/4 layer) as the second layer 3b, respectively, the respective substrates were bonded together with an adhesive layer (acrylic adhesive layer) interposed so that the longitudinal directions of the respective substrates were in the same direction, thereby obtaining substrate/alignment film/(λ/2 layer)/adhesive layer/(λ/4 layer)/alignment film/substrate. For the second phase difference plate 3b, the apparent in-plane phase difference value Re2(550) at a wavelength of 550 nm was 139 nm, and the apparent in-plane phase difference value Re2(450) at a wavelength of 450 nm was 106 nm. In addition, since the phase difference value of TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties mentioned above. When viewed from the λ/2 layer side, the orientation angle was 75° for the λ/2 layer and 15° for the λ/4 layer with respect to the longitudinal direction of the TAC.

(2nd phase plate 4b)

<Production of 4b on the 1st floor>

A first layer 4b was produced under the same conditions as the first layer 1b, except that the alignment direction of the photo-alignment film of the first layer 1b was 75° to the longitudinal direction of the TAC. The film thickness of the obtained λ/2 layer was measured with a laser microscope, and it was 1.8 μm. The in-plane phase difference value was measured using KOBRA-WR manufactured by Oji Scientific Instruments. As a result, the in-plane phase difference value at a wavelength of 550 nm was Re(550)=270 nm, and the in-plane phase difference value at a wavelength of 450 nm was Re(450)=291 nm. In addition, since the phase difference value at a wavelength of 550 nm of the TAC is approximately 0, it does not affect the optical properties. The alignment angle was 75° to the longitudinal direction of the TAC.

<Production of 2nd floor 4b>

A second layer 4b was produced under the same conditions as the second layer 1b, except that the rubbing treatment angle of the second layer 1b was -15° with respect to the longitudinal direction of the TAC. The in-plane phase difference value at a wavelength of 550 nm was Re(550)=142 nm, and the in-plane phase difference value at a wavelength of 450 nm was Re(450)=153.4 nm. In addition, since the phase difference value of the TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties. The orientation angle was -15° with respect to the longitudinal direction of the TAC.

After corona treatment was performed on the phase difference film side of the substrate/alignment film/(λ/2 layer) as the first layer 4b and the substrate/alignment film/(λ/4 layer) as the second layer 4b, respectively, the respective substrates were bonded together with an adhesive layer (acrylic adhesive layer) interposed so that the longitudinal directions of the respective substrates were in the same direction, thereby obtaining substrate/alignment film/(λ/2 layer)/adhesive layer/(λ/4 layer)/alignment film/substrate. For the second phase difference plate 4b, the apparent in-plane phase difference value Re2(550) at a wavelength of 550 nm was 139 nm, and the apparent in-plane phase difference value Re2(450) at a wavelength of 450 nm was 106 nm. In addition, since the phase difference value of TAC at a wavelength of 550 nm is approximately 0, it does not affect the optical properties mentioned above. When viewed from the λ/2 layer side, the orientation angle was -75° for the λ/2 layer and -15° for the λ/4 layer with respect to the longitudinal direction of the TAC.

[4] Adhesive layer

As the third bonding layer (17) and the adhesive layer (19), an acrylic adhesive layer (storage elastic modulus at 23°C: 1.3 MPa) with a thickness of 25 μm and bonded to a peeling film on both sides was used.

[5] Polarizer

A polyvinyl alcohol film having a thickness of 20 ㎛, a degree of polymerization of 2400, and a degree of saponification of 99% or more was uniaxially stretched on a hot roll at a stretching ratio of 4.5 times, and, while maintaining the tension, was immersed in a dyeing bath at 28°C containing 0.05 parts by mass of iodine and 5 parts by mass of potassium iodide per 100 parts by mass of water for 60 seconds.

Next, it was immersed in a 64°C boric acid aqueous solution 1 containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water for 110 seconds. Next, it was immersed in a 67°C boric acid aqueous solution 2 containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water for 30 seconds. Thereafter, it was washed with 10°C pure water and dried to obtain a polarizer. The polarizer had a thickness of 8 μm and a boron content of 4.3 mass%.

[6] Production of optical laminates (Examples 1 to 12, Comparative Examples 1 to 3)

A second protective film (triacetyl cellulose, thickness 20 μm) was attached to one surface of a polarizer using a water-based adhesive (second bonding layer (15)), and a first protective film (for Comparative Example 1, a first protective film without a surface treatment layer) was attached to the other surface using a water-based adhesive (first bonding layer (13)), using a roll bonding machine. After bonding, a drying process was performed at 80° C. for 3 minutes. A linear polarizing plate (10) having protective films laminated on both surfaces of a polarizer (14) was obtained. The linear polarizing plate (10) was laminated in this order: a surface treatment layer (11), a first protective film (12), a first bonding layer (13), a polarizer (14), a second bonding layer (15), and a second protective film (16). In these laminates, the angle θ1 formed by the ground axis of the first protective film and the absorption axis of the polarizer is shown in Table 3. In each example, the surface treatment layer composition used to form the surface treatment layer, the first protective film used for the first phase difference plate, and the second phase difference plate are shown in Table 3.

After cutting the linear polarizing plate (10) into a rectangle with the longitudinal direction being the absorption axis of PVA, an adhesive layer (third bonding layer (17)) is interposed on the surface of the second protective film (16) of the linear polarizing plate (10), the substrate is peeled off from the first layer surface side of the second phase plate (18), and the second phase plate (18) is bonded so that the first layer surface side is positioned on the linear polarizing plate (10) side, and further, the substrate is peeled off from the second layer surface side of the second phase plate (18), and an adhesive layer (19) is bonded to the peeled surface to obtain an optical laminate (1). In the optical laminate (1), the second phase plate (18) is a second phase plate 1b to 4b as shown in Table 3. In the optical laminate (1), the angle θ2 between the ground axis of the first layer and the absorption axis of the polarizer of the linear polarizing plate (10) is shown in Table 3.

[7] Evaluation

An organic EL display device was manufactured by bonding each optical laminate (1) to an organic EL display element through an adhesive layer (19).

(1) Observation of transmitted light

The organic EL display device was displayed as a white display, and the appearance of the white display was observed through polarizing sunglasses by changing the display angle. In addition, during the observation, it was observed whether there was a difference in the color taste or visibility of the image viewed in vertical display and horizontal display. The above observation results were evaluated based on the following criteria. The results are shown in Table 3. In Table 3, the color taste observed in vertical display and the color taste observed in horizontal display are expressed as (color taste observed in vertical display/color taste observed in horizontal display).

A: No matter what viewing angle I looked at, the appearance of the white mark did not differ at all.

B: I felt a slight difference in the appearance of the white mark depending on the display angle.

C: I felt a difference in the appearance of the white mark depending on the display angle.

D: Depending on the display angle, there was a difference in the appearance of the white display, and there was an angle where the display turned black.

(2) Observation of reflected light

The organic EL display device was set to a black display, and the display angle was changed to observe the appearance of the black display through polarized sunglasses. In addition, the color of the image recognized during the observation was observed. The above observation results were evaluated based on the following criteria. The results are shown in Table 3. In Table 3, when a color other than black was observed, that color is also shown.

A: No matter what viewing angle I was looking at, the appearance of the black mark did not differ at all.

B: I felt a slight difference in the appearance of the black mark depending on the display angle.

C: I felt a difference in the appearance of the black mark depending on the display angle.

(3) Observation of transmitted light in all directions

An organic EL display device was displayed as a white display, and the coloration of the white display in the diagonal direction (in the range of elevation angle 60° and azimuth angle 0 to 360°) was observed through polarizing sunglasses. The results of the observation were evaluated based on the following criteria, and the results are shown in Table 3.

A: I didn't feel any discoloration on the white mark.

B: I felt a little discoloration on the white mark.

C: I felt discoloration on the white mark.

(4) Observation of reflected light from all directions

The organic EL display device was set as a black display, and the coloring of the black display in the diagonal direction (in the range of elevation angle 60° and azimuth angle 0 to 360°) was observed through polarizing sunglasses. The results of the observation were evaluated based on the following criteria, and the results are shown in Table 3.

A: I didn't notice any difference in the coloring of the black mark.

B: I felt a little discoloration on the black mark.

C: I felt discoloration on the black mark.

[Table 3]

1: Optical laminate
11: Surface treatment layer
12: 1st protective film
13: 1st layer of glue
14: Polarizer
15: Second layer of glue
16: 2nd protective film
17: Third layer of adhesion
18: 2nd phase plate
19: Adhesive layer

Claims (8)

It has a first phase plate, a polarizer, a second phase plate, and an adhesive layer in this order.
The above first phase plate,
It is arranged so that the angle θ1 that the ground axis forms with respect to the absorption axis of the polarizer is 40° to 50° or -40° to -50°, and also
If the in-plane phase difference value for light with a wavelength of λ nm is Re1(λ), it satisfies the relationship of the following equation (1),
The above second phase plate,
A polymerizable liquid crystal compound comprising two or more phase contrast layers including a polymerized liquid crystal cured product,
At least two of the above-mentioned two-layer or more phase-shifted layers have their ground axes intersecting each other within the plane,
An optical laminate that satisfies the relationships of equations (2) and (3) below, where Re2(λ) is the in-plane phase difference value for light having a wavelength of λ nm.
1.0 ≤ Re1(450)/Re1(550) (1)
70㎚ ≤ Re2(450) ≤ 130㎚ (2)
Re2(450)/Re2(550) ≤ 1.0 (3) In the first paragraph,
The above first phase difference plate is an optical laminate made by stretching a thermoplastic resin film and having a thickness of 10 ㎛ to 100 ㎛. In paragraph 1 or 2,
The above first phase difference plate is an optical laminate in which Re1(λ) satisfies the following equations (4) and (5).
100㎚ ≤ Re1(450) ≤ 130㎚ (4)
100㎚ ≤ Re1(550) ≤ 130㎚ (5) In paragraph 1 or 2,
Further, it has a protective film disposed between the polarizer and the second phase difference plate,
The above protective film is an optical laminate having an in-plane phase difference value of 0 nm to 20 nm for light having a wavelength of 550 nm. In paragraph 1 or 2,
An optical laminate in which at least two of the phase difference layers constituting the second phase difference plate have ground axes intersecting in the plane. In paragraph 1 or 2,
An optical laminate, wherein among two or more phase difference layers constituting the second phase difference plate, the first layer, which is the layer closest to the polarizer, has an angle θ2 of its ground axis with respect to the absorption axis of the polarizer of 10° to 20° or -10° to -20°. In paragraph 1 or 2,
An optical laminate in which, among two or more phase difference layers constituting the second phase difference plate, the first layer, which is the layer closest to the polarizer, has a sign of the angle θ2 formed between its ground axis and the absorption axis of the polarizer, which is opposite to the sign of the angle θ1. In paragraph 1 or 2,
The first phase difference plate further has a layer having a predetermined ultraviolet absorption characteristic on the surface opposite to the polarizer,
An optical laminate having the above-described ultraviolet absorption characteristics, wherein the optical laminate satisfies the relationships of the following equations (6), (7), and (8), when the transmittance of light having a wavelength of λ㎚ is Tr(λ).
Tr(450) ≥ 85% (6)
30% ≤ Tr(420) ≤ 75% (7)
0% ≤ Tr(400) ≤ 10% (8)