JP7300906B2 - Optical layered body and image display device provided with the same - Google Patents

Description

The present invention relates to an optical layered body and an image display device having the same.

In recent years, from the viewpoint of improving portability by installing on a non-flat surface such as a curved surface or a folded surface, or by folding or forming a scroll shape, a flexible display having flexibility has been attracting attention. In such a flexible display, the front panel is also required to be flexible. A cover glass that has been used for an image display device without flexibility cannot be mounted on a flexible display. Therefore, a front plate made of a resin film is known as a front plate for a flexible display (Patent Document 1).

JP 2017-13492 A

A front panel having flexibility has a problem of insufficient impact resistance as compared with a cover glass used as a front panel of an image display device having no flexibility.

An object of the present invention is to provide an optical layered body having good flexibility suitable for a flexible display and excellent impact resistance, and an image display device having the same.

The present invention provides the following optical layered body and an image display device having the same.
[1] An optical laminate comprising a front plate, a circularly polarizing plate, and a first bonding layer for bonding the front plate and the circularly polarizing plate,
The circularly polarizing plate comprises a linear polarizing plate and a retardation layer in order from the first bonding layer side,
The front plate includes an outer layer forming the outermost surface of the optical layered body, and an inner layer provided so as to be in contact with the outer layer and the first bonding layer,
The outer layer is a first resin film,
The inner layer has a thickness of 100 μm or less,
The optical layered body, wherein the optical layered body has a withstand load of 20 g or more in a ball drop test.

[2] When the in-plane retardation value of the front plate at a wavelength of 550 nm is R0 (550) and the thickness direction retardation value of the front plate at a wavelength of 550 nm is Rth (550), the following formula is satisfied: (1) and formula (2):
2000nm≦R0(550)≦15000nm (1)
5000 nm≦Rth(550)≦15000 nm (2)
The optical layered product according to [1], which satisfies the relationship:

[3] [1] or [2], wherein the product of the tensile modulus of elasticity of the inner layer at a temperature of 23° C. and a relative humidity of 55% and the thickness of the inner layer is 80 MPa mm or more and 700 MPa mm or less; An optical laminate as described.

[4] Any one of [1] to [3], wherein the inner layer includes a second resin film and a second bonding layer for bonding the second resin film and the outer layer. The optical laminate according to any one of the above.

[5] The tensile elastic modulus of the second resin film at a temperature of 23 ° C. and a relative humidity of 55% is a [MPa], the thickness of the second resin film is b [μm], and the second bonding layer When the thickness of is c [μm], the following formula (3):
(a×b×10 ⁻³ )+(c/2)≧55 (3)
The optical layered product according to [4], which satisfies the relationship:

[6] The optical laminate according to [4] or [5], wherein the second resin film has a tensile elastic modulus a [MPa] of 7000 MPa or less at a temperature of 23° C. and a relative humidity of 55%.

[7] The optical laminate according to any one of [4] to [6], wherein the second bonding layer is an adhesive layer.

[8] The product of the tensile modulus of elasticity of the outer layer at a temperature of 23° C. and a relative humidity of 55% and the thickness of the outer layer is 100 MPa mm or more and 800 MPa mm or less of [1] to [7]. The optical layered body according to any one of the above.

[9] The optical layered body according to any one of [1] to [8], wherein the optical layered body has a critical bending number of 100,000 times or more in a bending test.

[10] The optical layered body according to any one of [1] to [9], wherein the optical layered body is an antireflection film.

[11] An image display device comprising the optical layered body according to any one of [1] to [10], wherein the front plate is arranged on the front surface.

According to the optical layered body of the present invention, it is possible to provide an image display device having excellent impact resistance while having good flexibility suitable for flexible displays.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows typically an example of the optical laminated body of this invention. 1 is a schematic cross-sectional view schematically showing an example of an image display device of the present invention; FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, the scale of each component is adjusted appropriately 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)
FIG. 1 is a schematic cross-sectional view schematically showing an example of the optical layered body of this embodiment. The optical laminate 100 includes a front plate 10, a circularly polarizing plate 30, and a first bonding layer 20. As shown in FIG. 1, the front plate 10, the first bonding layer 20, and the A circularly polarizing plate 30 is provided. The first bonding layer 20 is a layer for bonding the front plate 10 and the circularly polarizing plate 30 together. The front plate 10 includes an outer layer 11 forming the outermost surface of the optical layered body 100 and an inner layer 12 provided so as to be in contact with the outer layer 11 and the first bonding layer 20 . The circularly polarizing plate 30 includes a linearly polarizing plate 31 and a retardation layer 32 in order from the first bonding layer 20 side.

The optical laminate 100 can constitute an image display device as described later. Moreover, since the optical laminate 100 includes the circularly polarizing plate 30, it can also be used as an antireflection film.

The optical laminate 100 is an image display device (flexible display) that can be bent, rolled, etc., because the outer layer 11 of the front plate 10 is the first resin film, and the thickness of the inner layer is 100 μm or less. can be used for The optical laminate 100 preferably has flexibility such that the limit number of bends is 100,000 times or more in a bendability test in Examples described later, and the limit number of bends is more preferably 150,000 times or more. More preferably, it is 10,000 times or more. Accordingly, the optical laminate 100 can be suitably applied to flexible displays. A flexibility test can be performed by the method of the example mentioned later.

Light emitted from the display element side of an image display device having the optical layered body 100 through the optical layered body 100 and observed through sunglasses having linear polarization characteristics (hereinafter sometimes referred to as "polarized sunglasses") ( Light that enters from the circularly polarizing plate 30 side of the optical laminate 100, exits from the front plate 10 side, and passes through the polarized sunglasses) presents a specific transmission color according to the phase difference value of the front plate. As a result, the displayed image can be visually recognized even through polarized sunglasses. On the other hand, when an image display device having a front plate with R0 (550) and Rth (550) of less than 10 nm is provided with a linear polarizing plate, when the image display device is viewed through polarized sunglasses, the absorption of the linear polarizing plate Depending on the angle formed by the axis and the absorption axis of the polarizer of the polarizing sunglasses, the luminance is greatly reduced, and a phenomenon called blackout occurs in which the displayed image becomes difficult to see.

The load resistance of the optical layered body 100 in the ball drop test is 20 g or more, preferably 21 g or more, more preferably 22 g or more, may be 25 g or more, and is usually 50 g or less and 40 g or more. It may be below. When the load resistance is within the above range, it is possible to impart excellent impact resistance to the optical laminate 100 even when the outer layer 11 of the front plate 10 is the first resin film. Therefore, by using the optical layered body 100, it is possible to provide a flexible display having flexibility and excellent impact resistance. The withstand load in the ball drop test is measured by the method described in Examples below.

The withstand load of the optical layered body 100 in the ball drop test can be adjusted by the rigidity (tensile modulus, thickness), yield point elongation, yield stress, etc. of each layer forming the optical layered body 100 . For example, the rigidity of the inner layer 12 described later, the type of pressure-sensitive adhesive or adhesive forming the second bonding layer 12b described later contained in the inner layer 12, the thickness of the second bonding layer 12b, and the first bonding layer 20 It can be adjusted by the type of pressure-sensitive adhesive or adhesive used, the thickness of the first bonding layer 20, and the like.

When the optical laminate 100 is used as an antireflection film, the reflectance is preferably 10% or less, more preferably 7% or less, even more preferably 5.5% or less. The reflectance can be measured using a spectrophotometer (CM-2600d, manufactured by Konica Minolta, Inc.).

Although the thickness of the optical laminate 100 is not particularly limited, it is preferably 220 μm or less, more preferably 180 μm or less, even more preferably 150 μm or less so as to exhibit good flexibility. , 40 μm or more, and may be 70 μm or more.

Although the shape of the optical layered body 100 in the surface direction is not particularly limited, it preferably has a square shape, and more preferably has a rectangular shape. When the optical laminate 100 has a rectangular shape, the length of the long side is preferably 50 mm to 500 mm, and may be 100 mm to 400 mm, and the length of the short side is, for example, 30 mm to 400 mm. is preferred, and may be 60 mm to 300 mm. The optical layered body 100 may have a rounded rectangular shape in which at least one of the corners of the rectangular shape is rounded, or may have a rectangular shape having a notch on at least one side. Further, the optical layered body 100 may be provided with a hole penetrating in the layering direction.

(Front plate)
As shown in FIG. 1 , the front plate 10 includes an outer layer 11 forming the outermost surface of the optical layered body 100 and an inner layer 12 provided so as to be in contact with the outer layer 11 and the first bonding layer 20 . The front plate 10 is a plate-like body that can transmit light. In the image display device including the optical layered body 100, the front plate 10 can function as a layer for protecting the display elements and the like of the image display device. The front plate 10 may not only have a function of protecting the front surface of the image display device, but also have a function as a touch sensor, a blue light cut function, and the like.

The front plate 10 may have a viewing angle adjustment function. In this case, for the front plate 10, the in-plane retardation value of the front plate at a wavelength of 550 nm is R0 (550), and the thickness direction retardation value of the front plate at a wavelength of 550 nm is Rth (550). (1) and formula (2):
2000nm≦R0(550)≦15000nm (1)
5000 nm≦Rth(550)≦15000 nm (2)
It is preferable to satisfy the relationship of

When the front panel 10 satisfies the relationships of formulas (1) and (2), the image display device using the optical laminate 100 through polarized sunglasses can be viewed from the front or obliquely. In addition, the retardation of the optical layered body can make it difficult for color unevenness, iridescent coloring, to occur. As a result, it is possible to provide the optical layered body 100 which is excellent in impact resistance and flexibility, and which is also excellent in visibility.

The in-plane retardation value R0 (550) of the front plate 10 is more preferably 2500 nm or more, and even more preferably 5000 nm or more. The thickness direction retardation value Rth(550) of front plate 10 is more preferably 8000 nm or more, even more preferably 9000 nm or more, and even more preferably 10000 nm or more.

The stiffness represented by the product of the tensile elastic modulus of the front plate 10 at a temperature of 23° C. and a relative humidity of 55% and the thickness of the front plate 10 is preferably 100 MPa·mm or more, more preferably 150 MPa·mm or more. It may be 300 MPa·mm or more, preferably 5000 MPa·mm or less, may be 4000 MPa·mm or less, or may be 3000 MPa·mm or less. Since the front plate 10 forms the outermost surface of the optical laminate 100, if the rigidity of the front plate 10 is reduced, it becomes difficult to obtain the surface protection function of the display panel of the image display device. , flexibility tends to decrease.

The tensile elastic modulus of the front plate 10 at a temperature of 23° C. and a relative humidity of 55% is preferably 3000 MPa or more, more preferably 5000 MPa or more, preferably 20000 MPa or less, and 15000 MPa or less. is more preferred. When the tensile modulus of elasticity of the outer layer 11 becomes small, the surface hardness tends to be difficult to obtain and the scratch resistance tends to decrease. The tensile modulus of the outer layer 11 at a temperature of 23 ° C. and a relative humidity of 55% can be measured by the method described in the examples described later. This is the value measured by

The angle formed by the slow axis of the front plate 10 and the absorption axis of the linear polarizing plate 31 is preferably 0° or more, more preferably 30° or more, even more preferably 35° or more, The angle is preferably 65° or less, more preferably 60° or less, even more preferably 55° or less, and most preferably 45°.

The thickness of the front plate 10 is not particularly limited, but is preferably 250 μm or less, may be 200 μm or less, and is usually 40 μm or more so as to exhibit good flexibility and good impact resistance. , 70 μm or more.

(outer layer)
The outer layer 11 forming the front plate 10 is the outermost layer of the optical layered body 100 . The outer layer 11 has a function of imparting surface hardness required to the optical laminate 100 and a function of protecting other layers laminated on the outer layer 11 . The first resin film forming the outer layer 11 is not limited as long as it is a film that can transmit light, and is a resin film having a hard coat layer provided on at least one surface of the base film to improve surface hardness. may

The rigidity represented by the product of the tensile modulus of elasticity of the outer layer 11 at a temperature of 23° C. and a relative humidity of 55% and the thickness of the outer layer 11 is preferably 90 MPa·mm or more, and more preferably 100 MPa·mm or more. is more preferably 250 MPa mm or more, preferably 2000 MPa mm or less, more preferably 1200 MPa mm or less, even more preferably 800 MPa mm or less, and 600 MPa - mm or less may be sufficient. Since the outer layer 11 forms the outermost surface of the optical layered body 100, when the rigidity of the outer layer 11 becomes small, it becomes difficult to obtain a sufficient surface hardness of the optical layered body 100, and scratch resistance tends to decrease. Flexibility tends to decrease as the rigidity of the outer layer 11 increases.

The rigidity of the outer layer 11 is preferably greater than the rigidity of the inner layer 12 , the rigidity of the first bonding layer 20 , and the rigidity of the circularly polarizing plate 30 .

The tensile modulus of the outer layer 11 at a temperature of 23° C. and a relative humidity of 55% is preferably 3000 MPa or more, more preferably 5000 MPa or more, and preferably 20000 MPa or less, and 15000 MPa or less. is more preferred. When the tensile modulus of elasticity of the outer layer 11 becomes small, the surface hardness tends to be difficult to obtain and the scratch resistance tends to decrease. The tensile modulus of the outer layer 11 at a temperature of 23 ° C. and a relative humidity of 55% can be measured by the method described in the examples described later. This is the value measured by

The thickness of the outer layer 11 is usually 30 μm or more, and may be 50 μm or more, and is usually 100 μm or less, and may be 80 μm or less. If the thickness of the outer layer 11 is small, the impact resistance tends to decrease, and if the thickness of the outer layer 11 increases, the flexibility tends to decrease.

The first resin film forming the outer layer 11 may be a first retardation film having retardation properties. In this case, the in-plane retardation value of the outer layer 11 at a wavelength of 550 nm may be, for example, 0 nm or more, may be 50 nm or more, may be 300 nm or less, or may be 200 nm or less. good too. The thickness direction retardation value of the outer layer 11 at a wavelength of 550 nm may be, for example, 0 nm or more, may be 100 nm or more, may be 3000 nm or less, or may be 2000 nm or less.

The first resin film is not limited as long as it is a resin film that can transmit light. For example, triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene, polyamide, polyetherimide, poly(meth)acryl, polyimide, polyether Sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl (meth)acrylate, polyethylene terephthalate, polybutylene Examples thereof include films formed of polymers such as terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These polymers can be used alone or in combination of two or more. When the image display device 300 is a flexible display, it is made of a polymer such as polyimide, polyamide, polyamideimide, etc., which has excellent flexibility and can be configured to have high strength and high transparency. A resin film such as the one described above is preferably used.

The first resin film may be a film in which a hard coat layer is provided on at least one surface of the base film to further improve hardness. The hard coat layer may be formed on one surface of the substrate film, or may be formed on both surfaces. When the image display device, which will be described later, is a touch panel type image display device, the surface of the outer layer 11 serves as a touch surface, so a resin film having a hard coat layer is preferably used. By providing a hard coat layer, a resin film having improved hardness and scratch resistance can be obtained. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of ultraviolet curable resins include (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard coat layer may contain additives in order to improve strength. Additives are not limited and include inorganic microparticles, organic microparticles, or mixtures thereof.

(inner layer)
The inner layer 12 constituting the front plate 10 is provided between the outer layer 11 and the first bonding layer 20 and is in direct contact with both the outer layer 11 and the first bonding layer 20 . The inner layer 12 can be provided to improve the impact resistance of the optical stack 100 . The inner layer 12 has a thickness of 100 μm or less, which facilitates giving the optical layered body 100 flexibility suitable for a flexible display. In addition, the inner layer 12 may have retardation properties for imparting the retardation values represented by the above formulas (1) and (2) to the front plate 10, and the inner layer 12 may have the above formula ( It may have phase difference values represented by 1) and (2). As shown in FIG. 1, the inner layer 12 may include a second resin film 12a and a second bonding layer 12b for bonding the second resin film 12a and the outer layer 11 together. . The opposite side of the second bonding layer 12b of the second resin film 12a may be in direct contact with the first bonding layer 20 . Moreover, the inner layer 12 may further include two or more resin films and a bonding layer for bonding two or more resin films.

The stiffness represented by the product of the tensile elastic modulus of the inner layer 12 at a temperature of 23° C. and a relative humidity of 55% and the thickness of the inner layer 12 is preferably 10 MPa·mm or more, and preferably 40 MPa·mm or more. is more preferably 80 MPa·mm or more, preferably 1000 MPa·mm or less, more preferably 700 MPa·mm or less, and even more preferably 640 MPa·mm or less. When the rigidity of the inner layer 12 is within the above range, it is easy to improve the impact resistance while ensuring the flexibility of the optical layered body 100 .

The stiffness of the inner layer 12 is preferably smaller than the stiffness of the outer layer 11 and the stiffness of the circularly polarizing plate 30 , and may be greater than the stiffness of the first bonding layer 20 .

The tensile modulus of the inner layer 12 at a temperature of 23° C. and a relative humidity of 55% is preferably 1000 MPa or more, more preferably 1500 MPa or more, may be 2000 MPa or more, and is 10000 MPa or less. , more preferably 9000 MPa or less, and may be 8000 MPa or less. When the rigidity of the inner layer 12 is within the above range, it is easy to improve the impact resistance while ensuring the flexibility of the optical layered body 100 . The tensile modulus of the inner layer 12 at a temperature of 23 ° C. and a relative humidity of 55% can be measured by the method described in the examples described later. This is the value measured by

When the inner layer 12 includes the second resin film 12a and the second bonding layer 12b, the tensile elastic modulus a [MPa] of the second resin film 12a at a temperature of 23° C. and a relative humidity of 55% is 1000 MPa or more. is preferably 1500 MPa or more, may be 2000 MPa or more, may be 3000 MPa or more, may be 3500 MPa or more, is preferably 7000 MPa or less, and is preferably 6000 MPa or less. It is more preferable that there is, and it may be 5000 MPa or less. The tensile elastic modulus of the second resin film 12a at a temperature of 23° C. and a relative humidity of 55% can be measured by the method described above. When the inner layer 12 includes two or more resin films and includes a lamination layer for laminating the two or more resin films to each other, the tensile modulus of the second resin film 12a is 2 or more resin films. It refers to the tensile modulus of the whole including the film and the lamination layer.

The thickness of the inner layer 12 is 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and preferably 20 μm or more, more preferably 40 μm or more. If the thickness of the inner layer 12 is small, the impact resistance tends to decrease, and if the thickness of the inner layer 12 increases, the flexibility tends to decrease.

The second resin film 12a may be a second retardation film having retardation properties. In this case, the in-plane retardation value of the inner layer 12 at a wavelength of 550 nm may be, for example, 100 nm or more, may be 1000 nm or more, or may be 3000 nm or more. The thickness direction retardation value of the inner layer 12 at a wavelength of 550 nm can be, for example, 2500 nm or more, and may be 3000 nm or more. When the inner layer 12 includes two or more resin films and includes a bonding layer for bonding the two or more resin films to each other, the in-plane retardation value and the thickness direction orientation of the second resin film 12a described above The retardation value refers to the in-plane retardation value and the thickness direction retardation value of the entire film including two or more resin films and bonding layers.

When the inner layer 12 contains the second retardation film and the outer layer 11 is the first retardation film, in the optical laminate 100, the slow axis direction of the first retardation film and the slow axis direction of the second retardation film It is preferable to laminate the outer layer 11 and the inner layer 12 so that their axial directions are aligned. As a result, good visibility can be obtained when an image display device using the optical layered body 100 is viewed through polarized sunglasses.

Further, the angle formed by the slow axis of the first retardation film and the absorption axis of the circular polarizer 30, and the angle formed by the slow axis of the second retardation film and the absorption axis of the circular polarizer 30 are 25° or more. is preferably 30° or more, more preferably 35° or more, and preferably 65° or less, more preferably 60° or less, and 55° or less. is more preferred, and 45° is most preferred.

The thickness b [μm] of the second resin film 12a is not particularly limited. may be 50 μm or more. The thickness b [μm] of the second resin film 12a may be 150 μm or less, or 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and 50 μm or less. It is even more preferable to have When the inner layer 12 includes two or more resin films and includes a lamination layer for laminating the two or more resin films to each other, the thickness of the second resin film 12a is the thickness of the two or more resin films and It refers to the total thickness including the lamination layer.

Rigidity represented by the product of the tensile elastic modulus a [MPa] of the second resin film 12a and the thickness b [μm] of the second resin film 12a (“a×b× 10 ⁻³ ″) [MPa·mm] is preferably 10 MPa·mm or more, more preferably 40 MPa·mm or more, further preferably 80 MPa·mm or more, and 150 MPa·mm or more. 200 MPa·mm or more, or 300 MPa·mm or more. The rigidity of the second resin film 12a is preferably 1500 MPa·mm or less, more preferably 1000 MPa·mm or less, may be 800 MPa·mm or less, or may be 500 MPa·mm or less. . When the rigidity of the second resin film 12a is within the above range, it is easy to improve the impact resistance while ensuring the flexibility of the optical layered body 100 .

The second resin film 12a is not limited as long as it is a light-transmissive film, and for example, a film formed of a polymer exemplified as the first resin film forming the outer layer 11 can be used. When the second resin film 12a is the second retardation film, the second resin film 12a can preferably use a film made of a polymer such as polyethylene naphthalate or polyethylene terephthalate.

(Second bonding layer)
The second bonding layer 12b may be an adhesive layer, but is preferably an adhesive layer. Since the second bonding layer 12b is a pressure-sensitive adhesive layer, the rigidity of the inner layer 12 can be easily adjusted within the range described above, and the impact resistance of the optical layered body 100 can be easily improved. The pressure-sensitive adhesive layer and the adhesive layer can be constructed using materials described later.

The thickness c [μm] of the second bonding layer 12b is not particularly limited, but may be, for example, 1 μm or more, may be 3 μm or more, may be 5 μm or more, or may be 10 μm or more. , may be 15 μm or more, or 20 μm or more, and is preferably 50 μm or less, and may be 30 μm or less.

The tensile elastic modulus a [MPa] of the second resin film 12a of the inner layer 12 constituting the front plate 10, the thickness b [μm] of the second resin film 12a, and the thickness c of the second bonding layer 12b [μm] is the following formula (3):
(a×b×10 ⁻³ )+(c/2)≧55 (3)
It is preferable to satisfy the relationship of

By satisfying the relationship of the above formula (3), the durability of the optical layered body 100 to the pen drop test can be improved. It is considered that the pressure applied to the bottom side (circularly polarizing plate 30 side) of the optical layered body 100 can be reduced by improving the durability to the pen drop test. Therefore, when a touch panel sensor or a display laminate is provided on the bottom surface side of the optical laminate 100 like a composite optical laminate or an image display device described later, by using an optical laminate that satisfies the relationship of the above formula (3), It is possible to improve the durability of the composite optical laminate and the image display device. For example, in the composite optical layered body, it becomes easier to suppress malfunction of the touch panel sensor provided on the bottom side (the circularly polarizing plate 30 side) of the optical layered body 100 . Moreover, by satisfying the formula (3), the durability to the ball drop test can be improved. The durability to the pen drop test can be evaluated by the method described in Examples below.

The value of the left side of the above formula (3) is more preferably 60 or more, more preferably 80 or more, may be 100 or more, may be 200 or more, and may be 250 or more is more preferable, and may be 300 or more. The value of the left side of the above formula (3) is usually 500 or less, and may be 400 or less.

The values of the tensile elastic modulus a [MPa] of the second resin film 12a, the thickness b [μm], the thickness c [μm] of the second bonding layer 12b, and a×b×10 ⁻³ in the above formula (3) can each be in the ranges described above, for example.

The pressure-sensitive adhesive layer forming the second bonding layer 12b is composed of a pressure-sensitive adhesive composition whose main component is a (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin. be able to. Among them, a pressure-sensitive adhesive composition using a (meth)acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance, etc., is preferable. The adhesive composition may be thermosetting.

Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition include butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-(meth)acrylate. Polymers or copolymers containing one or more of (meth)acrylic acid esters such as ethylhexyl as monomers are preferably used. Preferably, the base polymer is copolymerized with a polar monomer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, glycidyl ( Monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., such as meth)acrylates, can be mentioned.

The pressure-sensitive adhesive composition may contain only the above base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a metal ion having a valence of 2 or more, which forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound, which forms an amide bond with a carboxyl group; Examples include epoxy compounds and polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred.

The adhesive composition contains fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, tackifiers, fillers (metal powders and other inorganic powders). etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, photopolymerization initiators, and other additives.

It can be formed by applying an organic solvent-diluted solution of the pressure-sensitive adhesive composition onto a substrate and drying it. When an active energy ray-curable pressure-sensitive adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating the formed pressure-sensitive adhesive layer with an active energy ray.

The adhesive layer forming the second bonding layer 12b can be composed of an adhesive composition. Examples of the adhesive composition include water-based adhesive compositions such as polyvinyl alcohol-based resin aqueous solutions and water-based two-component urethane emulsion adhesives; A composition etc. can be mentioned.

(First bonding layer)
The first bonding layer 20 is a layer interposed between the inner layer 12 of the front plate 10 and the circularly polarizing plate 30 to bond them together, and is a pressure-sensitive adhesive layer or an adhesive layer. The pressure-sensitive adhesive layer and the adhesive layer can be constructed using the materials described above. The second bonding layer 12b is preferably an adhesive layer from the viewpoint of improving the impact resistance while ensuring the flexibility of the optical layered body 100 .

The storage elastic modulus of the first bonding layer 20 at a temperature of 23° C. and a relative humidity of 55% is preferably 0.001 MPa or more, may be 0.01 MPa or more, or may be 0.1 MPa or more. Also, it is preferably 0.5 MPa or less, and may be 0.3 MPa or less. When the storage elastic modulus of the first bonding layer 20 is within the above range, it is easy to improve the impact resistance while ensuring the flexibility of the optical layered body 100 . The storage elastic modulus of the first bonding layer 20 at a temperature of 23° C. and a relative humidity of 55% can be measured by the method described in Examples below.

The thickness of the first bonding layer 20 may be, for example, 1 μm or more, may be 3 μm or more, may be 5 μm or more, may be 10 μm or more, and is usually 100 μm or less. , is preferably 50 μm or less, and may be 30 μm or less.

(Circularly polarizing plate)
The circularly polarizing plate 30 includes a linearly polarizing plate 31 and a retardation layer 32 in order from the first bonding layer 20 side. In addition, since the circularly polarizing plate 30 can suppress the emission of reflected light of external light, the optical layered body 100 can be provided with a function as an antireflection film.

The thickness of the circularly polarizing plate 30 is usually 5 μm or more, may be 20 μm or more, may be 25 μm or more, may be 30 μm or more, and is preferably 80 μm or less, and may be 60 μm or less. is more preferable. When the thickness of the circularly polarizing plate 30 is within the above range, the effect on the load resistance of the optical layered body 100 in the ball drop test is small compared to other layers forming the optical layered body 100, and the effect is ignored. be able to.

(linear polarizing plate)
The linear polarizing plate 31 has a function of selectively transmitting linearly polarized light in one direction from non-polarized light such as natural light. The linear polarizing plate 31 includes, as a polarizer, a stretched film to which a dye having anisotropic absorption is adsorbed, or a film coated with a dye having anisotropic absorption and cured. Dyes having absorption anisotropy include, for example, dichroic dyes. Specifically, iodine and dichroic organic dyes are used as dichroic dyes. Dichroic organic dyes include dichroic direct dyes composed of disazo compounds such as CIDIRECT RED 39, and dichroic direct dyes composed of compounds such as trisazo and tetrakisazo. As a film coated with a dye having anisotropic absorption, which is used as a polarizer, a stretched film adsorbed with a dye having anisotropic absorption, or a composition or dichroic dye having liquid crystallinity. A film having a layer obtained by applying and curing a composition containing a chromatic dye and a polymerizable liquid crystal, and the like. A film coated with and cured with a dye having anisotropic absorption is preferred because there is no limitation in the bending direction, compared to a stretched film to which a dye having anisotropic absorption is adsorbed.

The visibility correction polarization degree (Py) of the polarizer included in the linear polarizing plate 31 is usually 97% or more, preferably 98% or more, and more preferably 99% or more. The luminosity correction transmittance (Ty) of the polarizer is usually 40% or more, preferably 41% or more, more preferably 42% or more, and may be 44% or more.

(1) Polarizing plate having a stretched film as a polarizer A linear polarizing plate having as a polarizer a stretched film to which a dye having absorption anisotropy is adsorbed will be described. The stretched film, which is a polarizer and absorbs a dye having anisotropic absorption, is usually produced by uniaxially stretching a polyvinyl alcohol resin film and dyeing the polyvinyl alcohol resin film with a dichroic dye. Manufactured through a step of adsorbing a dichroic dye, a step of treating a polyvinyl alcohol resin film on which the dichroic dye is adsorbed with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution. Such a polarizer may be used as a linear polarizing plate as it is, or may be used as a linear polarizing plate by laminating a transparent protective film on one or both sides of the polarizer. The thickness of the polarizer thus obtained is preferably 2 μm to 40 μm.

A polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. Polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Other monomers copolymerizable with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol %, preferably 98 mol % or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is generally about 1,000 to 10,000, preferably 1,500 to 5,000.

A film obtained by forming such a polyvinyl alcohol-based resin is used as a raw film for a polarizer. The method of forming the polyvinyl alcohol-based resin into a film is not particularly limited, and the film can be formed by a known method. The film thickness of the polyvinyl alcohol base film can be, for example, about 10 μm to 150 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. It is also possible to carry out uniaxial stretching in these multiple stages. In the uniaxial stretching, the film may be uniaxially stretched between rolls having different circumferential speeds, or may be uniaxially stretched using hot rolls. The uniaxial stretching may be dry stretching in which the film is stretched in the atmosphere, or wet stretching in which the polyvinyl alcohol resin film is stretched in a swollen state using a solvent. The draw ratio is usually about 3 to 8 times.

The material of the protective film that is attached to one or both sides of the polarizer is not particularly limited, but examples thereof include cyclic polyolefin resin films, cellulose acetate-based resins such as triacetyl cellulose and diacetyl cellulose. Films known in the art, such as resin films, polyester resin films made of resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polycarbonate resin films, (meth)acrylic resin films, polypropylene resin films, etc. can be mentioned. From the viewpoint of thinning, the thickness of the protective film is usually 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and usually 5 μm or more, preferably 20 μm or more. . The protective film may or may not have retardation.

(2) Polarizing plate having a film formed of a liquid crystal layer as a polarizer A linear polarizing plate having a film formed of a liquid crystal layer as a polarizer will be described. As a film coated with a dye having absorption anisotropy used as a polarizer, a composition containing a dichroic dye having liquid crystallinity, or a composition containing a dichroic dye and a liquid crystal compound is used as a base material. A film obtained by coating and curing may be mentioned. The film may be used as a linear polarizing plate with the base removed or together with the base, or may be used as a linear polarizing plate with a protective film on one or both sides thereof. Examples of the protective film include the same ones as the linear polarizing plate having the above stretched film as a polarizer.

It is preferable that the film obtained by applying and curing a dye having anisotropic absorption is thin, but if the film is too thin, the strength tends to decrease and workability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, more preferably 0.5 μm or more and 3 μm or less.

Specific examples of the film obtained by coating the dye having absorption anisotropy include films described in JP-A-2013-37353 and JP-A-2013-33249.

(retardation layer)
The retardation layer 32 may be one layer or two or more layers. The retardation layer 32 includes a λ/4 layer, and may further include a λ/2 layer and a positive C layer. When the retardation layer 32 includes a λ/2 layer, a λ/2 layer and a λ/4 layer are laminated in order from the linear polarizing plate 31 side. When the retardation layer 32 includes a positive C layer, the λ / 4 layer and the positive C layer may be laminated in order from the linear polarizing plate 31 side, and the positive C layer and λ / 4 layer in order from the linear polarizing plate 31 side. May be laminated.

The retardation layer 32 may be formed from the resin film exemplified as the material of the protective film, or may be formed from a layer obtained by curing a polymerizable liquid crystal compound. The retardation layer 32 may further include an alignment film and a base film, and may have a bonding layer for bonding the λ/4 layer and the λ/2 layer or the positive C layer. . The lamination layer is a pressure-sensitive adhesive layer or an adhesive layer, and the above-described layers can be used.

(Composite optical laminate)
The composite optical laminate includes an optical laminate 100 and a touch panel sensor. The touch panel sensor is provided on the circularly polarizing plate 30 side of the optical laminate 100 . The optical layered body 100 and the touch panel sensor can be laminated via, for example, a bonding layer for the touch panel sensor. The lamination layer is a pressure-sensitive adhesive layer and an adhesive layer, and the pressure-sensitive adhesive layer and the adhesive layer can be configured using the materials described above.

(Image display device)
FIG. 2 is a schematic cross-sectional view schematically showing an example of the image display device of this embodiment. The image display device has an optical laminate 100 including a front plate 10 disposed on the front surface (viewing side), a display laminate 200 including a display unit, and a third bonding layer 40. The optical laminate A display laminate 200 is laminated on the circularly polarizing plate 30 side of 100 with a third bonding layer 40 interposed therebetween. The third bonding layer 40 is for bonding the circularly polarizing plate 30 and the display layered body 200 in the optical layered body 100 . When laminating the optical layered body 100 and the display layered body 200 , for example, the third bonding layer 40 is provided on the circularly polarizing plate 30 of the optical layered body 100 , and the display layer is formed on the third bonding layer 40 . Body 200 may be laminated. The lamination layer for the display laminate is a pressure-sensitive adhesive layer or an adhesive layer, and the pressure-sensitive adhesive layer and the adhesive layer can be configured using the materials described above.

The image display device 300 may be a flexible display panel. The image display device, which is a flexible display, may be configured to be foldable with the viewing side surface inside, or may be configured to be wound.

The image display device 300 can be configured as a touch panel type image display device. A touch panel type image display device can be configured using the composite optical laminate described above, and the touch panel sensor side of the composite optical laminate and the display laminate 200 are connected, for example, via a bonding layer for the display laminate. can be stacked together. The lamination layer for the display laminate is a pressure-sensitive adhesive layer and an adhesive layer, and the pressure-sensitive adhesive layer and the adhesive layer can be configured using the materials described above. In the touch panel type image display device, the front panel 10 included in the optical layered body 100 of the composite optical layered body constitutes a touch surface.

Examples of display units included in the display laminate 200 include display units including display elements such as liquid crystal display elements, organic EL display elements, inorganic EL display elements, plasma display elements, and field emission display elements.

The image display device 300 can be used as mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic signboards, measuring instruments and gauges, office equipment, medical equipment, computing equipment, and the like.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "parts" in Examples and Comparative Examples are % by mass and parts by mass.

[Thickness measurement]
The thickness of each layer was measured using an ellipsometer (M-220, manufactured by JASCO Corporation) or a contact-type film thickness meter (MH-15M, counter TC101, MS-5C, manufactured by Nikon Corporation).

[Measurement of tensile modulus]
The tensile modulus was measured using a tensile tester (AG-1S, manufactured by Shimadzu Corporation) at a temperature of 23° C. and a relative humidity of 55%. When the measurement object was a retardation film, the tensile elastic modulus in the slow axis direction was measured.

[Measurement of in-plane retardation value and thickness direction retardation value]
The in-plane retardation value and thickness direction retardation value were measured using a birefringence measuring device (Axo Sacn, manufactured by Axometrics).

[Ball drop test]
The circularly polarizing plate side of the optical laminate obtained in each example and each comparative example was laminated to a 0.7 mm alkali-free glass via a 5 μm thick acrylic adhesive (manufactured by Sumitomo Chemical Co., Ltd.). A test sample (1) was prepared. This test sample (1) was placed on a steel stage so that the front plate side faces upward, and a ball drop test ball made of steel was vertically freely dropped from a height of 50 cm to obtain an optical laminate. It was made to collide with the alkali-free glass via. Test balls weighing 1 g, 3 g, 4 g, 7 g, 12 g, 16 g, 19 g, 22 g, 25 g, 32 g, and 36 g were used. The maximum value among test ball weights in which no cracks, scratches, or dents were observed in the glass) was called the ball drop test load capacity (g), and was used as an index of impact resistance.

[Flexibility test]
The circularly polarizing plate side of the optical laminate obtained in each example and each comparative example was passed through a 20 μm thick acrylic adhesive (manufactured by Sumitomo Chemical Co., Ltd.) with a flexibility evaluation equipment (CFT-150AC, Covotech). After fixing it in a flat state (unbent state), bend it so that the front plate side faces inside at a rate of 30 times per minute under the conditions of a curvature radius of 3 mm and a temperature of 25 ° C. Then, the bending operation to return to the original flat state was repeated, and the number of bending times when cracks or whitening occurred at the bending position was confirmed as the critical number of bending times. Occurrence of cracks and floating of the lamination layer (adhesive layer) in the bent area due to the bending operation,
A for cases where the number of flexions reaches 200,000 times,
B when the number of bends is 100,000 times or more and less than 200,000 times,
C when the number of bends is less than 100,000 times,
As a result, the flexibility test was evaluated.

[Visibility test]
The circularly polarizing plate side of the optical layered body obtained in each example and each comparative example was placed on a backlight unit (manufacturer: Shinkosha Co., Ltd., product name: LIGHTNING LED viewer 5000A4). The optical layered body was visually observed from the front plate side through polarized sunglasses, and the state of occurrence of color unevenness in which the optical layered body turned iridescent was confirmed. The visibility test was carried out in two directions: the front direction, which is perpendicular to the surface of the front plate, and the oblique direction, which is a direction at 45° to the surface of the front plate. It was confirmed. When the color unevenness was hardly visible and good visibility was obtained, the color unevenness was judged to be "absent", and when the color unevenness was conspicuously visible, the color unevenness was judged to be "present".

[Pen drop test]
From the optical layered bodies obtained in each example and each comparative example, a rectangular piece having a long side of 150 mm and a short side of 70 mm was cut out using a super cutter. The circularly polarizing plate side of the cut piece was attached to the ITO layer side of the touch panel sensor via the adhesive layer to obtain a test sample (2). As the touch sensor panel, a panel composed only of a touch sensor pattern layer was used. The touch sensor pattern layer included an ITO layer as a transparent conductive layer and a cured layer of an acrylic resin composition as a separation layer, and had a thickness of 7 μm.

Next, in an environment with a temperature of 23 ° C. and a relative humidity of 55%, an evaluation pen weighing about 5.6 g (pen tip diameter: 0.75 mm) was positioned and held downward, and the pen for evaluation was dropped from that position toward the front panel side. On the front plate of the test sample (2), the bridge wiring (wiring that electrically connects the touch electrodes) of the conductive layer of the touch panel sensor is marked, and the pen tip falls on the marked bridge. The evaluation pen was dropped like this. For the test sample (2) in which the evaluation pen was dropped, observation with a scanning electron microscope (SEM) (SU8010, manufactured by Horiba) and confirmation of the touch panel sensor function were performed, and the occurrence of cracks and the operation of the touch panel sensor. but,
A when there is no crack and the touch panel sensor operates normally,
B when there is a crack and the touch panel sensor operates normally;
C if there is a crack and the touch panel sensor does not operate normally,
As a result, the pen drop test was evaluated.

[Example 1]
(Preparing the front panel)
As an outer layer, a first resin film having a thickness of 60 μm and having a hard coat layer formed on one side of a base film was prepared. The base film was a polyimide resin film with a thickness of 50 μm. The hard coat layer had a thickness of 10 μm and was a layer formed from a composition containing a dendrimer compound having a polyfunctional acrylic group at its end. The resulting outer layer had an in-plane retardation value of 133 nm at a wavelength of 550 nm, a thickness retardation value of 1754 nm at a wavelength of 550 nm, and a tensile modulus of 8000 MPa.

As an inner layer, a laminate was prepared in which a second bonding layer was formed on a second resin film. The second resin film is a polyethylene naphthalate (PEN) film (“Teonex”, manufactured by Teijin Limited) with a thickness of 34 μm, and the second bonding layer is an acrylic adhesive with a thickness of 5 μm (manufactured by Sumitomo Chemical Co., Ltd. )Met. The second resin film had an in-plane retardation value of 6933 nm at a wavelength of 550 nm, a thickness direction retardation value of 8959 nm at a wavelength of 550 nm, and a tensile modulus of 2400 MPa. The inner layer had a tensile modulus of elasticity of 2500 MPa and a stiffness of 98 MPa·mm.

The surface of the outer layer opposite to the side on which the hard coat layer was formed was bonded to the second bonding layer of the inner layer to obtain a front plate. The outer layer and the inner layer were laminated so that the slow axis direction of the first resin film forming the outer layer and the slow axis direction of the second resin film forming the inner layer were aligned. The in-plane retardation value R0 (550) at a wavelength of 550 nm and the thickness direction retardation value Rth (550) at a wavelength of 550 nm were measured for the obtained front plate. Table 1 shows the results.

(Preparation of linear polarizing plate)
A polyvinyl alcohol (PVA) film having an average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol % or more, and a thickness of 20 µm was prepared. After the PVA film was immersed in pure water at 30°C, it was iodine dyed by immersing it in an aqueous solution having a mass ratio of iodine/potassium iodide/water of 0.02/2/100 at 30°C (iodine dyeing step). . The PVA film that had undergone the iodine dyeing process was subjected to boric acid treatment by immersing it in an aqueous solution having a mass ratio of potassium iodide/boric acid/water of 12/5/100 at 56.5°C (boric acid treatment process). . After the PVA film that had undergone the boric acid treatment step was washed with pure water at 8° C., it was dried at 65° C. to obtain a polarizer in which iodine was adsorbed and oriented in polyvinyl alcohol. The stretching of the PVA film was performed in the iodine dyeing process and the boric acid treatment process. The total draw ratio of the PVA film was 5.3 times. The thickness of the obtained polarizer was 8 μm.

The polarizer obtained above and a 13 μm thick cycloolefin polymer (COP) film (ZF-14, manufactured by Nippon Zeon Co., Ltd., with an in-plane retardation value of 1 nm at a wavelength of 550 nm) are nip-rolled via a water-based adhesive. pasted together with The obtained laminate was dried at 60° C. for 2 minutes while maintaining the tension at 430 Nm to obtain a linear polarizing plate having a COP film on one side. The water-based adhesive consists of 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol (“Kuraray Poval KL318” manufactured by Kuraray Co., Ltd.), and a water-soluble polyamide epoxy resin (“Sumirez Resin 650” (solid concentration: 30%). Aqueous solution of (Taoka Chemical Co., Ltd.) and 1.5 parts were added.

・溶媒（９５部）：シクロペンタノン (Preparation of retardation layer)
A composition for forming a horizontal alignment film was obtained by mixing the following components and stirring the resulting mixture at a temperature of 80° C. for 1 hour.
· Photo-alignable material (5 parts) (weight average molecular weight: 30000):

- Solvent (95 parts): cyclopentanone

・重合性液晶化合物Ｂ（１０部）：

・レベリング剤（１部）：
Ｆ－５５６（ＤＩＣ株式会社製）
・重合開始剤（６部）：
２－ジメチルアミノ－２－ベンジル－１－（４－モルホリノフェニル）ブタン－１－オン（イルガキュア３６９、ＢＡＳＦジャパン株式会社製） Further, the following components were mixed, N-methyl-2-pyrrolidone (NMP) was further added so that the solid content concentration was 13%, and the mixture was stirred at 80°C for 1 hour to form a horizontally aligned liquid crystal layer. A composition for Polymerizable liquid crystal compound A below was synthesized according to the method described in JP-A-2010-31223, and polymerizable liquid crystal compound B below was synthesized according to the method described in JP-A-2009-173893.
- Polymerizable liquid crystal compound A (90 parts):

- Polymerizable liquid crystal compound B (10 parts):

- Leveling agent (1 part):
F-556 (manufactured by DIC Corporation)
- Polymerization initiator (6 parts):
2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369, manufactured by BASF Japan Ltd.)

A cyclic olefin resin (COP) film (ZF-14-50, manufactured by Nippon Zeon Co., Ltd.) was subjected to corona treatment. The corona treatment was performed once using TEC-4AX (manufactured by Ushio Inc.) under conditions of an output of 0.78 kW and a treatment speed of 10 m/min. The composition for forming a horizontal alignment film obtained above was applied to the corona-treated surface of this COP film with a bar coater and dried at 80° C. for 1 minute. Using a polarized UV irradiation device (“SPOT CURE SP-9”, manufactured by Ushio Inc.), the coating film was irradiated with an axial angle of 45° so that the integrated light amount at a wavelength of 313 nm was 100 mJ/cm ² . A horizontal alignment film having a thickness of 100 nm was obtained by exposing the film to polarized UV light.

Subsequently, the composition for forming a horizontal alignment liquid crystal layer obtained above was applied to this horizontal alignment film using a bar coater and dried at 120° C. for 1 minute. Using a high-pressure mercury lamp (“Unicure VB-15201BY-A”, manufactured by Ushio Inc.), the coating film is irradiated with ultraviolet rays (in a nitrogen atmosphere, integrated light intensity at a wavelength of 365 nm: 500 mJ/cm ² ). A λ/4 retardation layer, which is a horizontally aligned liquid crystal layer, was formed to obtain a retardation layer. The thickness of the λ/4 retardation layer was 2.3 µm. The obtained retardation layer has a COP film, a horizontal alignment film, and a λ/4 retardation layer in this order.

On the λ / 4 retardation layer side of the obtained retardation layer, a 5 μm thick acrylic adhesive (manufactured by Sumitomo Chemical Co., Ltd.) is laminated, and the adhesive and glass are laminated, and then the COP film is peeled off. Then, a sample for measurement was obtained. As a result of measuring the in-plane retardation value R0 _p (λ) at the wavelength λ of this measurement sample, R0 _p (450) = 119 nm, R0 _p (550) = 140 nm, R0 _p (650) = 144 nm, R0 _p (450)/R0 _p (550)=0.85, R0 _p (650)/R0 _p (550)=1.03, and the λ/4 retardation layer exhibited reverse wavelength dispersion. The λ/4 retardation layer was a positive A plate satisfying the relationship nx>ny≈nz.

Further, as a result of measuring the thickness direction retardation value Rth _p (λ) at the wavelength λ of the above measurement sample, Rth _p (450) = 61 nm, Rth _p (550) = 71 nm, Rth _p (650) = 73 nm. Met.

(Preparation of circularly polarizing plate)
The polarizer side of the linear polarizing plate obtained above and the λ / 4 retardation layer side of the retardation layer obtained above are laminated via a 5 μm thick acrylic adhesive (manufactured by Sumitomo Chemical Co., Ltd.). Then, the COP film of the retardation layer was peeled off to obtain a circularly polarizing plate. The linear polarizing plate and the retardation layer were bonded together so that the angle between the absorption axis of the polarizer and the slow axis of the λ/4 retardation layer was 45°. A circularly polarizing plate has a COP film (a COP film of a linearly polarizing plate), a polarizer, an acrylic pressure-sensitive adhesive, and a λ/4 retardation layer in this order.

(Fabrication of optical laminate)
The inner layer side of the front plate obtained above and the linear polarizing plate side of the circularly polarizing plate were pasted together via a 5 μm thick acrylic pressure-sensitive adhesive (manufactured by Sumitomo Chemical Co., Ltd.) to form an optical laminate having a thickness of 132 μm. got a body A ball drop test, a flexibility test, a visibility test, and a pen drop test were carried out using the obtained optical layered body. Table 1 shows the results.

[Example 2]
In the same manner as in Example 1, except that a high birefringence polyethylene terephthalate (PET) film ("Cosmoshine SRF" manufactured by Toyobo Co., Ltd.) having a thickness of 80 μm was used as the second resin film forming the inner layer. A front plate was obtained, and an optical laminate was obtained. The second resin film had an in-plane retardation value of 6187 nm at a wavelength of 550 nm, a thickness direction retardation value of 6320 nm at a wavelength of 550 nm, and a tensile modulus of 3800 MPa. The inner layer had a tensile modulus of elasticity of 3900 MPa and a stiffness of 332 MPa·mm.

The in-plane retardation value R0 (550) at a wavelength of 550 nm and the thickness direction retardation value Rth (550) at a wavelength of 550 nm were measured for the obtained front plate. In addition, a ball drop test, a flexibility test, a visibility test, and a pen drop test were carried out using the obtained optical layered body. These results are shown in Table 1.

[Example 3]
A front plate was prepared in the same manner as in Example 1, except that a 45 μm-thick biaxially oriented polyethylene terephthalate (PET) film (“Lumirror”, manufactured by Toray Industries, Inc.) was used as the second resin film forming the inner layer. was obtained to obtain an optical laminate. The second resin film had an in-plane retardation value of 2655 nm at a wavelength of 550 nm, a thickness direction retardation value of 3455 nm at a wavelength of 550 nm, and a tensile modulus of 4000 MPa. The inner layer had a tensile modulus of elasticity of 4100 MPa and a stiffness of 205 MPa·mm.

The in-plane retardation value R0 (550) at a wavelength of 550 nm and the thickness direction retardation value Rth (550) at a wavelength of 550 nm were measured for the obtained front plate. In addition, a ball drop test, a flexibility test, a visibility test, and a pen drop test were carried out using the obtained optical layered body. These results are shown in Table 1.

[Example 4]
As the second resin film forming the inner layer, a uniaxially stretched cycloolefin polymer (COP) film (“ZF-14-23”, manufactured by Nippon Zeon Co., Ltd.) with a thickness of 23 μm is used, and the second bonding layer forming the inner layer. A front plate and an optical laminate were obtained in the same manner as in Example 1, except that a 20 μm-thick acrylic pressure-sensitive adhesive (manufactured by Sumitomo Chemical Co., Ltd.) was used. The second resin film had an in-plane retardation value of less than 1 nm at a wavelength of 550 nm, a thickness direction retardation value of less than 1 nm at a wavelength of 550 nm, and a tensile modulus of 2100 MPa. The inner layer had a tensile modulus of elasticity of 2300 MPa and a stiffness of 99 MPa·mm.

The in-plane retardation value R0 (550) at a wavelength of 550 nm and the thickness direction retardation value Rth (550) at a wavelength of 550 nm were measured for the obtained front plate. In addition, a ball drop test, a flexibility test, a visibility test, and a pen drop test were carried out using the obtained optical layered body. These results are shown in Table 1.

[Comparative Example 1]
A front plate was obtained and an optical laminate was obtained in the same manner as in Example 1, except that the inner layer was not provided. The in-plane retardation value R0 (550) at a wavelength of 550 nm and the thickness direction retardation value Rth (550) at a wavelength of 550 nm were measured for the obtained front plate. In addition, a ball drop test, a flexibility test, a visibility test, and a pen drop test were carried out using the obtained optical layered body. These results are shown in Table 1.

[Comparative Example 2]
Same as Example 1, except that a uniaxially stretched cycloolefin polymer (COP) film (“ZF-14-23”, manufactured by Nippon Zeon Co., Ltd.) with a thickness of 23 μm was used as the second resin film forming the inner layer. Then, a front plate was obtained, and an optical laminate was obtained. The second resin film had an in-plane retardation value of less than 1 nm at a wavelength of 550 nm, a thickness direction retardation value of less than 1 nm at a wavelength of 550 nm, and a tensile modulus of 2100 MPa. The inner layer had a tensile modulus of elasticity of 2200 MPa and a stiffness of 62 MPa·mm.

The in-plane retardation value R0 (550) at a wavelength of 550 nm and the thickness direction retardation value Rth (550) at a wavelength of 550 nm were measured for the obtained front plate. In addition, a ball drop test, a flexibility test, a visibility test, and a pen drop test were carried out using the obtained optical layered body. These results are shown in Table 1.

[Comparative Example 3]
As the second resin film forming the inner layer, a uniaxially stretched cycloolefin polymer (COP) film (“ZF-14-23”, manufactured by Nippon Zeon Co., Ltd.) with a thickness of 23 μm was coated with an acrylic soft coat layer with a thickness of 80 μm (“ UF8003G" manufactured by Kyoeisha Chemical Co., Ltd.) was used to obtain a front plate and an optical laminate in the same manner as in Example 1. The second resin film had an in-plane retardation value of less than 1 nm at a wavelength of 550 nm, a thickness direction retardation value of less than 1 nm at a wavelength of 550 nm, and a tensile modulus of 2100 MPa. The inner layer had a tensile modulus of elasticity of 2300 MPa and a stiffness of 248 MPa·mm.

The in-plane retardation value R0 (550) at a wavelength of 550 nm and the thickness direction retardation value Rth (550) at a wavelength of 550 nm were measured for the obtained front plate. In addition, a ball drop test, a flexibility test, a visibility test, and a pen drop test were carried out using the obtained optical layered body. These results are shown in Table 1.

10 Front plate 11 Outer layer 12 Inner layer 12a Second resin film 12b Second bonding layer 20 First bonding layer 30 Circularly polarizing plate 31 Linear polarizing plate 32 Retardation layer 40th 3 bonding layers, 100 optical layered body, 200 display layered body, 300 image display device.

Claims (9)

An optical laminate comprising a front plate, a circularly polarizing plate, and a first bonding layer for bonding the front plate and the circularly polarizing plate,
The circularly polarizing plate comprises a linear polarizing plate and a retardation layer in order from the first bonding layer side,
The front plate includes an outer layer forming the outermost surface of the optical layered body, and an inner layer provided so as to be in contact with the outer layer and the first bonding layer,
The outer layer is a first resin film,
The thickness of the outer layer is 30 μm or more,
The inner layer includes a second resin film and a second bonding layer for bonding the second resin film and the outer layer,
The inner layer has a thickness of 100 μm or less,
The tensile elastic modulus of the second resin film at a temperature of 23 ° C. and a relative humidity of 55% is a [MPa], the thickness of the second resin film is b [μm], and the thickness of the second bonding layer is When c [μm], the following formula (3):
(a×b×10 ⁻³ )+(c/2)≧80 (3)
satisfy the relationship of
The optical layered body, wherein the optical layered body has a withstand load of 20 g or more in a ball drop test. In the front plate, when the in-plane retardation value of the front plate at a wavelength of 550 nm is R0 (550) and the thickness direction retardation value of the front plate at a wavelength of 550 nm is Rth (550), the following formula (1) and equation (2):
2000nm≦R0(550)≦15000nm (1)
5000 nm≦Rth(550)≦15000 nm (2)
2. The optical laminate according to claim 1, which satisfies the relationship of 3. The optical laminate according to claim 1, wherein the product of the tensile elastic modulus of the inner layer at a temperature of 23° C. and a relative humidity of 55% and the thickness of the inner layer is 80 MPa·mm or more and 700 MPa·mm or less. . The optical laminate according to any one of claims 1 to 3, wherein the second resin film has a tensile elastic modulus a [MPa] of 7000 MPa or less at a temperature of 23°C and a relative humidity of 55%. The optical laminate according to any one of claims 1 to 4, wherein the second bonding layer is an adhesive layer. The product of the tensile elastic modulus of the outer layer at a temperature of 23 ° C. and a relative humidity of 55% and the thickness of the outer layer is 100 MPa mm or more and 800 MPa mm or less, according to any one of claims 1 to 5 An optical laminate as described. The optical layered body according to any one of claims 1 to 6, wherein the optical layered body has a critical bending number of 100,000 times or more in a bending test. The optical laminate according to any one of claims 1 to 7, wherein the optical laminate is an antireflection film. An image display device comprising the optical laminate according to any one of claims 1 to 8, wherein the front plate is arranged on the front surface.

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