JP7257461B2 - optical laminate - Google Patents

Description

The present invention relates to optical laminates.

2. Description of the Related Art In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices) have rapidly spread. 2. Description of the Related Art An image display device typically uses an optical laminate including a polarizing plate and an optical functional layer (eg, anti-glare layer, anti-reflection layer). As such an optical laminate, for example, a polarizing plate with an antireflection layer and an antiglare layer is known (for example, Patent Document 1). In the polarizing plate with an antireflection layer and an antireflection layer, an antireflection laminate including an antireflection layer is attached to the visible side of the polarizing plate via an adhesive layer, and an antireflection laminate including an antireflection layer. The body is attached to the viewing side of the anti-glare laminate via an adhesive layer. In such a polarizing plate with an antireflection layer and an antiglare layer, fine unevenness called orange peel occurs on the viewing side surface, which may adversely affect the display performance of the image display device.

In addition, a polarizing plate having partial polarizing performance is required in order to cope with the diversification of the shape and high functionality of image display devices. As such a polarizing plate, a polarizing plate having a polarizer in which a non-polarizing portion is formed by chemical treatment is known. When the optical layered body includes a polarizing plate containing a non-polarizing portion, a pressure-sensitive adhesive layer is provided on the opposite side of the polarizing plate from the viewing side, and the optical layered body is attached to the display panel. There is a problem that air bubbles tend to enter between them.

JP 2018-155998 A

The present invention has been made to solve the above-mentioned conventional problems, and the main purpose thereof is to suppress orange peel and to provide an optical layered body and display when the optical layered body is bonded to an image display panel. An object of the present invention is to provide an optical layered body capable of suppressing the entry of air bubbles between itself and a panel.

An optical laminate according to an embodiment of the present invention comprises a polarizing plate including a non-polarizing portion, a first optical function body bonded to the viewing side of the polarizing plate via a first pressure-sensitive adhesive layer, and the first A reinforcing layer bonded via a second adhesive layer to the viewing side of the optical function body, and a second optical function body bonded via a third adhesive layer to the viewing side of the reinforcing layer , a fourth adhesive layer located on the side opposite to the viewing side with respect to the polarizing plate, the first adhesive layer, the second adhesive layer, the third adhesive layer and Each thickness of the fourth pressure-sensitive adhesive layer is 17 μm or less.
In one embodiment, the optical layered body has an elastic modulus of 2700 MPa or more.
In one embodiment, each thickness of the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer, and the third pressure-sensitive adhesive layer is less than or equal to the thickness of the fourth pressure-sensitive adhesive layer.
In one embodiment, the sum of the thickness of the first optical function body, the thickness of the reinforcing layer, and the thickness of the second optical function body is 200 μm or less.
In one embodiment, the surface of the fourth pressure-sensitive adhesive layer opposite to the polarizing plate has unevenness of 0.5 μm or more and 1.0 μm or less.
In one embodiment, the optical layered body includes a first retardation layer bonded to the side opposite to the viewing side of the polarizer, and a second retardation layer bonded to the side opposite to the viewing side of the first retardation layer. 2 retardation layers, the fourth pressure-sensitive adhesive layer is disposed on the opposite side of the second retardation layer from the viewing side, and the first retardation layer has nx>ny>nz The second retardation layer exhibits refractive index characteristics of nz>nx>ny.

According to an embodiment of the present invention, an optical layered body that can suppress orange peel and prevent air bubbles from entering between the optical layered body and the display panel when the optical layered body is attached to the display panel is provided. can be realized.

1 is a schematic cross-sectional view of an optical stack according to one embodiment of the invention; FIG.

Although representative embodiments of the present invention will be described below, the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the in-plane direction orthogonal to the slow axis (i.e., fast axis direction) and "nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re(λ)” is the in-plane retardation of the film measured at 23° C. with light of wavelength λ nm. For example, "Re(450)" is the in-plane retardation of a film measured with light having a wavelength of 450 nm at 23°C. Re(λ) is obtained by the formula: Re=(nx−ny)×d, where d (nm) is the thickness of the film.
(3) Thickness direction retardation (Rth)
“Rth(λ)” is the retardation in the thickness direction of the film measured at 23° C. with light having a wavelength of λ nm. For example, "Rth(450)" is the retardation in the thickness direction of the film measured at 23°C with light having a wavelength of 450 nm. Rth(λ) is determined by the formula: Rth=(nx−nz)×d, where d (nm) is the thickness of the film.
(4) Nz Coefficient The Nz coefficient is obtained by Nz=Rth/Re.
(5) Angles When referring to angles in this specification, unless otherwise specified, the angles include angles in both clockwise and counterclockwise directions.

A. 1. Overall Configuration of Optical Layered Body FIG. 1 is a schematic cross-sectional view of an optical layered body according to one embodiment of the present invention. The optical layered body 1 of the illustrated example includes a polarizing plate 2 including a non-polarizing portion 21a, a first optical function body 3 bonded to the viewing side of the polarizing plate 2 with a first adhesive layer 61 interposed therebetween, a first 1, the reinforcing layer 5 bonded to the visible side of the optical function body 3 via the second adhesive layer 62, and the second adhesive layer 5 bonded to the visible side of the reinforcing layer 5 via the third adhesive layer 63. and a fourth pressure-sensitive adhesive layer 9 located on the opposite side of the polarizing plate 2 from the viewing side. In other words, the optical laminate 1 includes the second optical function body 4, the third adhesive layer 63, the reinforcing layer 5, the second adhesive layer 62, the first optical function body 3, A first adhesive layer 61 , a polarizing plate 2 , and a fourth adhesive layer 9 are provided in this order from the viewing side of the optical layered body 1 . More specifically, the non-polarizing portion 21 a is included in the polarizer 21 included in the polarizing plate 2 . The optical layered body 1 can be attached to an image display panel with the fourth adhesive layer 9 .
Each thickness of the first adhesive layer 61, the second adhesive layer 62, the third adhesive layer 63, and the fourth adhesive layer 9 is 17 μm or less.
The orange peel that occurs on the surface of the optical layered body on the viewing side may be caused by unevenness of the pressure-sensitive adhesive layer. On the other hand, with the configuration as described above, since the thickness of each pressure-sensitive adhesive layer is equal to or less than the above upper limit, it is possible to suppress the unevenness of the pressure-sensitive adhesive layer from affecting the surface of the optical layered body on the viewing side. It is possible to suppress the occurrence of orange peel on the viewing side surface of the optical layered body. However, if the thickness of the fourth pressure-sensitive adhesive layer is equal to or less than the above upper limit, unevenness (especially dents) may occur on the panel-side surface of the fourth pressure-sensitive adhesive layer due to the influence of the non-polarizing portion included in the polarizing plate. . In this case, air bubbles are likely to enter between the optical layered body and the display panel when the optical layered body is attached to the display panel by the fourth pressure-sensitive adhesive layer. In this respect, with the configuration as described above, since the reinforcing layer is provided between the first optical function body and the second optical function body, it is possible to improve the elastic modulus of the optical layered body. Even if the thickness of the fourth pressure-sensitive adhesive layer is equal to or less than the above upper limit, it is possible to prevent air bubbles from entering between the fourth pressure-sensitive adhesive layer of the optical layered body and the display panel. Therefore, it is possible to realize an optical layered body that can suppress orange peel and prevent air bubbles from entering between the optical layered body and the display panel when the optical layered body is attached to the display panel.

In one embodiment of the present invention, the elastic modulus of the optical layered body 1 is 2700 MPa or more, preferably 3000 MPa or more, and typically 4000 MPa or less. The elastic modulus (tensile properties) of the optical layered body can be measured by a measuring method based on JIS K 7127 using an autograph manufactured by Shimadzu Corporation. If the elastic modulus of the optical layered body is equal to or higher than the above lower limit, it is possible to stably prevent air bubbles from entering between the optical layered body and the display panel when the optical layered body is attached to the display panel.

The first adhesive layer 61, the second adhesive layer 62, the third adhesive layer 63, and the fourth adhesive layer 9 may have the same thickness, or may have different thicknesses. good too. In one embodiment of the present invention, each thickness of the first adhesive layer 61, the second adhesive layer 62 and the third adhesive layer 63 has the same thickness as the fourth adhesive layer. It is equal to or less than the thickness of the agent layer 9 . More specifically, the thickness of each of the first adhesive layer 61, the second adhesive layer 62, and the third adhesive layer 63 is preferably 15 μm or less, more preferably 13 μm or less, and is typically 5 μm or more. The thickness of the fourth adhesive layer 9 is preferably 16 μm or less, typically 10 μm or more, preferably 14 μm or more. If the thickness of each pressure-sensitive adhesive layer is within such a range, it is possible to stably suppress orange peel and more stably suppress the entry of air bubbles between the optical layered body and the display panel.

In one embodiment of the present invention, the sum of the thickness of the first optical function body 3, the thickness of the reinforcing layer 5 and the thickness of the second optical function body 4 is 200 μm or less, preferably 180 μm or less, more preferably It is 170 μm or less, typically 140 μm or more, preferably 150 μm or more. If the sum of the thicknesses of the first optical function body, the reinforcing layer, and the second optical function body is equal to or less than the above upper limit, warping of the optical layered body in a high humidity environment can be suppressed. If the sum of the thicknesses of the first optical function body, the reinforcing layer, and the second optical function body is equal to or greater than the above lower limit, the elastic modulus of the optical layered body can be stably adjusted within the above range.

In one embodiment of the present invention, the surface of the fourth pressure-sensitive adhesive layer 9 opposite to the polarizing plate 2 has irregularities of 0.5 μm or more and 1.0 μm or less. The unevenness on the surface of the fourth adhesive layer 9 is positioned so as to correspond to the non-polarizing portion 21a of the polarizer 21, and overlaps the non-polarizing portion 21a in the thickness direction. The surface of the fourth adhesive layer 9 opposite to the polarizing plate 2 is substantially flat except for irregularities. The unevenness is typically a recess corresponding to the non-polarizing portion 21a. The dimension of the unevenness in the thickness direction of the fourth adhesive layer (the depth of the recessed portion) is in the above range (0.5 μm or more and 1.0 μm or less) based on the surface of the fourth adhesive layer 9 other than the recessed portion. is.
The unevenness of the pressure-sensitive adhesive layer surface can be measured by NewView7300 manufactured by Zygo. If the size of the unevenness formed on the surface of the fourth pressure-sensitive adhesive layer is within such a range, it is possible to more stably prevent air bubbles from entering between the optical layered body and the display panel.

In one embodiment of the present invention, the optical layered body 1 includes the first retardation layer 7 attached to the opposite side of the polarizing plate 2 from the viewing side, and the first retardation layer 7 to the opposite side from the viewing side. and a bonded second retardation layer 8 . In this case, the fourth adhesive layer 9 is arranged on the side opposite to the viewing side of the second retardation layer 8 . The first retardation layer 7 preferably exhibits refractive index characteristics of nx>ny>nz. The second retardation layer 8 preferably exhibits refractive index characteristics of nz>nx>ny. According to such a configuration, it is possible to impart a desired optical compensation function to the optical layered body.

In one embodiment of the present invention, the thickness of the optical laminate 1 is typically 330 μm or less, preferably 310 μm or less, more preferably 300 μm or less, and typically 250 μm or more, preferably 270 μm or more. is. When the thickness of the optical layered body is equal to or less than the above upper limit, warping of the optical layered body in a high-humidity environment can be stably suppressed. Moreover, since the thickness of the optical layered body is equal to or greater than the above lower limit, the elastic modulus of the optical layered body can be stably adjusted within the above range.

The constituent elements of the optical layered body will be described below.

B. Polarizing Plate In one embodiment of the present invention, the polarizing plate 2 comprises a polarizer 21 and a protective layer 22 arranged on the viewing side of the polarizer 21 . The protective layer 22 is typically attached to the viewing side of the polarizer 21 via any appropriate adhesive layer (adhesive layer, adhesive layer: not shown). That is, the polarizing plate 2 may consist of the polarizer 21 , the adhesive layer, and the protective layer 22 . The protective layer 22 is positioned between the polarizer 21 and the first adhesive layer 61 and is in contact with the first adhesive layer 61 . The protective layer 22 is pressure-sensitively adhered to the first adhesive layer 61 . Moreover, the polarizing plate 2 may further include a second protective layer on the side opposite to the viewing side of the polarizer 21 .

B-1. Polarizer Any appropriate polarizer can be employed as the polarizer 21 . For example, the resin film forming the polarizing plate 2 may be a single-layer resin film or a laminate of two or more layers. A resin film forming the polarizer 21 contains a dichroic substance. Dichroic substances include, for example, iodine and organic dyes. Dichroic substances can be used alone or in combination. Among the dichroic substances, iodine is preferred. For example, when the non-polarizing portion 21a is formed by chemical decolorization, the iodine complex contained in the polarizer 21 can be appropriately reduced, and the non-polarizing portion 21a can be provided with properties suitable for use in the camera section, for example. be.

A specific example of a polarizer composed of a single-layer resin film is a PVA-based resin film that has been dyed with iodine and stretched (typically, uniaxially stretched). The dyeing with iodine is performed by, for example, immersing the PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial drawing is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or may be performed while dyeing. Moreover, you may dye after extending|stretching. If necessary, the PVA-based resin film is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, and the like. For example, by immersing the PVA-based resin film in water and washing it with water before dyeing, it is possible not only to wash away stains and anti-blocking agents on the surface of the PVA-based film, but also to swell the PVA-based resin film to prevent uneven dyeing. etc. can be prevented.

Specific examples of the polarizer obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and the resin A polarizer obtained by using a laminate with a PVA-based resin layer formed by coating on a substrate can be mentioned. A polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material is obtained, for example, by applying a PVA-based resin solution to the resin base material and drying the resin base material. forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In one embodiment of the present invention, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may further include stretching the laminate in air at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. In addition, in one embodiment of the present invention, the laminate is preferably subjected to drying shrinkage treatment to shrink the laminate by 2% or more in the width direction by heating while conveying in the longitudinal direction. Typically, the manufacturing method of the present embodiment includes subjecting the laminate to an in-air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing auxiliary stretching, it is possible to improve the crystallinity of PVA and achieve high optical properties even when PVA is coated on a thermoplastic resin. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when immersed in water in the subsequent dyeing process or stretching process, resulting in high optical properties. can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance of the orientation of the polyvinyl alcohol molecules and deterioration of the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. This can improve the optical properties of the polarizer obtained through treatment steps such as dyeing treatment and underwater stretching treatment in which the laminate is immersed in a liquid. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate. Then, any appropriate protective layer may be laminated on the release surface according to the purpose. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. These publications are incorporated herein by reference in their entirety.

The polarizer 21 is preferably composed of a laminate of two or more layers, and more preferably composed of a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate.

The polarizer 21 has a non-polarizing portion 21a. The planar view shape of the non-polarizing portion 21a may be changed as appropriate depending on the application. Examples of the planar shape of the non-polarizing portion 21a include a circle, an ellipse, a square, a rectangle, and a rhombus. The non-polarized portion 21a is typically a bleached portion that is bleached by chemical treatment. More specifically, the non-polarizing portion 21a is formed by bringing a predetermined portion of the polarizer 21 into contact with a treatment liquid (typically, a basic solution). When the polarizer 21 contains iodine as the dichroic substance, when a predetermined portion of the polarizer 21 is brought into contact with a basic solution, the iodine content of the contact portion is easily reduced, and the contact portion is selectively non-existent. A polarizing portion 21a can be formed. As a result, a predetermined portion of the polarizer 21 can be decolorized, and the non-polarized portion 21a can be formed in the polarizer 21 . When the iodine complex is destroyed to form the non-polarized portion, iodine may remain in the non-polarized portion. Then, as the polarizer is used, an iodine complex is formed again, and the non-polarizing portion may no longer have the desired properties. On the other hand, when the non-polarizing portion 21a is formed by contacting the basic solution and the polarizer 21, iodine itself is absorbed into the polarizer 21 (substantially, the non-polarizing portion 21a) as the basic solution is removed. ). As a result, the change in characteristics of the non-polarizing portion 21a due to the use of the polarizer 21 can be suppressed.

The content of the dichroic substance (typically iodine) in the non-polarizing portion 21a is preferably 1.0% by weight or less, more preferably 0.5% by weight or less, and even more preferably 0.2% by weight or less. is. If the content of the dichroic substance in the non-polarizing portion is within this range, the desired transparency can be sufficiently imparted to the non-polarizing portion. For example, when a non-polarizing section is made to correspond to a camera section of an image display device, extremely excellent photographing performance can be achieved in terms of both brightness and color. On the other hand, the lower limit of the content of the dichroic substance in the non-polarized portion is usually below the detection limit. When iodine is used as the dichroic substance, the iodine content can be obtained from, for example, a calibration curve prepared in advance using standard samples from X-ray intensities measured by fluorescent X-ray analysis.

The difference between the content of the dichroic substance in the portion of the polarizer 21 other than the non-polarizing portion 21a and the content of the dichroic substance in the non-polarizing portion 21a is preferably 0.5% by weight or more, more preferably 1% by weight or more. If the content difference is within such a range, a non-polarizing portion having desired transparency can be formed.

The polarizer 21 excluding the non-polarizing portion 21a preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer 21 is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. . The degree of polarization of the polarizer 21 is preferably 97.0% or higher, more preferably 99.0% or higher, still more preferably 99.9% or higher.

The transmittance of the non-polarized portion 21a (for example, the transmittance measured with light having a wavelength of 550 nm at 23° C.) is preferably 50% or more, more preferably 60% or more, still more preferably 75% or more, and particularly preferably 90%. That's it. With such a transmittance, the non-polarized portion has desired transparency. As a result, when the polarizing plate is arranged so that the non-polarizing portion corresponds to the camera portion of the image display device, it is possible to prevent adverse effects on the photographing performance of the camera.

When the non-polarized portion 21a is formed by contact with a treatment liquid (typically a basic solution), since the dichroic substance (iodine) has been removed from the non-polarized portion 21a, the non-polarized portion 21a is It can be thinner than the portion other than the non-polarizing portion 21a. Typically, the surface of the polarizer 21 opposite to the viewing side (the surface on the side of the fourth pressure-sensitive adhesive layer 9) is recessed in a portion corresponding to the non-polarizing portion 21a. On the other hand, the surface of the polarizer 21 on the viewing side (the surface on the side of the protective layer 22) is substantially flat without recesses in the portions corresponding to the non-polarizing portions 21a.

The thickness of the polarizer 21 excluding the non-polarizing portion 21a is preferably 15 μm or less, more preferably 12 μm or less, even more preferably 10 μm or less, particularly preferably 8 μm or less, and typically 1 μm or more, preferably 3 μm or more. be.

The thickness of the non-polarizing portion 21a with respect to the thickness of the polarizer 21 (thickness of the non-polarizing portion 21a/thickness of the polarizer 21) is typically less than 1.0, preferably 0.98 or less. is 0.80 or more, preferably 0.85 or more.

B-2. Protective Layer Protective layer 22 is formed of any suitable film that can be used as a protective layer for polarizer 21 . Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based resins. , polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based transparent resins. Thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may also be used. In addition, "(meth)acrylic resin" refers to acrylic resin and/or methacrylic resin. In addition, for example, a glassy polymer such as a siloxane-based polymer can also be used. Further, polymer films described in JP-A-2001-343529 (WO01/37007) can also be used. Materials for this film include, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in a side chain. can be used, for example, a resin composition comprising an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrudate of the resin composition.

In one embodiment of the present invention, protective layer 22 contains a (meth)acrylic resin. As the (meth)acrylic resin, for example, a (meth)acrylic resin having a glutarimide structure is used. (Meth)acrylic resins having a glutarimide structure, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006 -337491, JP 2006-337492, JP 2006-337493, JP 2006-337569, JP 2007-009182, JP 2009-161744, JP 2010-284840 It is described in the publication. These descriptions are incorporated herein by reference.

The thickness of the protective layer 22 is typically 300 μm or less, preferably 100 μm or less, more preferably 5 μm to 80 μm, still more preferably 10 μm to 60 μm. In addition, when the surface treatment is performed, the thickness of the protective layer 22 is the thickness including the thickness of the surface treatment layer.

C. First Optical Function Body The first optical function body 3 can impart desired optical functions to the optical laminate 1 . Examples of the first optical function body 3 include a reflection-preventing laminate and a sunglass countermeasure laminate.
The thickness of the first optical function body 3 is typically 20 μm to 60 μm, preferably 30 μm to 50 μm.

In one embodiment of the present invention, the first optical function body 3 is an anti-glare laminate 3a. The anti-reflection laminate 3 a includes an anti-reflection layer 32 and a first base material 31 arranged on the viewing side of the anti-reflection layer 32 . The anti-glare layer 32 is supported by the first base material 31 . The anti-glare layer 32 is arranged on the viewer side with respect to the protective layer 22 and is attached to the protective layer 22 via the first adhesive layer 61 . The anti-glare layer 32 is in contact with the first adhesive layer 61 and pressure-sensitively adhered to the first adhesive layer 61 . The first base material 31 is located on the opposite side of the anti-glare layer 32 from the first pressure-sensitive adhesive layer 61 . The first substrate 31 is in contact with the second adhesive layer 62 and pressure-sensitively adhered to the second adhesive layer 62 .

C-1. Anti-Reflection Layer The anti-reflection layer 32 is provided to prevent reflection of the user's face of the image display device, the keyboard of the image display device, external light (for example, fluorescent lamp), and the like. In one embodiment of the present invention, the anti-glare layer 32 is an alignment fixed layer of a liquid crystal compound. As used herein, the term "fixed alignment layer" refers to a layer in which a liquid crystal compound is aligned in a predetermined direction and the alignment state is fixed. In addition, the "alignment fixed layer" is a concept including an alignment cured layer obtained by curing a liquid crystal monomer. The liquid crystal compound may be a rod-like liquid crystal compound, a discotic (disk-like) liquid crystal compound, or a combination thereof.

In one embodiment of the invention, anti-glare layer 32 comprises a discotic liquid crystal compound. More specifically, the anti-glare layer 32 is a layer in which a discotic liquid crystal compound is fixed while oriented in a predetermined direction. Discotic liquid crystal compounds generally have a cyclic mother nucleus such as benzene, 1,3,5-triazine, or calixarene at the center of the molecule, and a linear alkyl group, alkoxy group, or substituted benzoyl A liquid crystal compound having a discotic molecular structure in which oxy groups and the like are radially substituted as side chains. Representative examples of discotic liquid crystals include C.I. Destrade et al., Mol. Cryst. Liq. Cryst. 71, 111 (1981), benzene derivatives, triphenylene derivatives, truxene derivatives and phthalocyanine derivatives; Kohne et al., Angew. Chem. 96, 70 (1984) and cyclohexane derivatives described in J. Am. M. In the report of Lehn et al., J. Am. Chem. Soc. Chem. Commun. , 1794 (1985); In the report of Zhang et al., J. Am. Am. Chem. Soc. 116, 2655 (1994), azacrown-based and phenylacetylene-based macrocycles. Further specific examples of discotic liquid crystal compounds include compounds described in JP-A-2006-133652, JP-A-2007-108732, JP-A-2010-244038, and JP-A-2014-214177. The descriptions of the above documents and publications are incorporated herein by reference. An anti-glare layer containing a discotic liquid crystal compound can typically be a so-called negative A-plate having a refractive index characteristic of nx=nz>ny.

In another embodiment, anti-glare layer 32 contains a rod-shaped liquid crystal compound. More specifically, in the anti-glare layer, the rod-like liquid crystal compounds are aligned in a predetermined direction (typically, the slow axis direction) (homogeneous alignment). Examples of rod-like liquid crystal compounds include liquid crystal compounds whose liquid crystal phase is a nematic phase (nematic liquid crystal). As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. Either lyotropic or thermotropic mechanism may be used to develop the liquid crystallinity of the liquid crystal compound. The liquid crystal polymer and liquid crystal monomer may be used alone or in combination. Any suitable liquid crystal monomer can be employed as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP-T-2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Specific examples of such polymerizable mesogenic compounds include LC242 (trade name) available from BASF, E7 (trade name) available from Merck, and LC-Sillicon-CC3767 (trade name) available from Wacker-Chem. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable. Specific examples of liquid crystal compounds are described in, for example, JP-A-2006-163343. The description of the publication is incorporated herein by reference. An anti-glare layer containing a rod-shaped liquid crystal compound can typically be a so-called positive A plate having a refractive index characteristic of nx>ny=nz.

The anti-glare layer 32 can typically function as a λ/2 plate. When the anti-reflection layer 32 functions as a λ/2 plate, the reflection can be effectively prevented by controlling the orientation angle (or slow axis direction). The in-plane retardation Re(550) of such anti-glare layer 32 is 220 nm to 320 nm, preferably 240 nm to 300 nm, and still more preferably 250 nm to 280 nm.

The angle formed by the slow axis of the anti-glare layer 32 and the absorption axis of the polarizer 21 is preferably 35° to 55°, more preferably 40° to 50°, still more preferably about 45°. be. By arranging the anti-reflection layer 32 functioning as a λ/2 plate at such an axial angle, the reflection can be effectively prevented.

The thickness of the anti-glare layer 32 is preferably 1 μm to 5 μm, more preferably 1 μm to 3 μm.

When an alignment film is used for aligning the liquid crystal compound, the anti-reflection laminate 3 a further includes an alignment film between the anti-reflection layer 32 and the first substrate 31 . That is, the anti-reflection laminate 3 a may be composed of the anti-reflection layer 32 , the alignment film, and the first base material 31 . The alignment film generally contains a polymer material as a main component. Representative examples of polymeric materials include polyvinyl alcohol, polyimide, and derivatives thereof. Modified or unmodified polyvinyl alcohol is preferred in one embodiment of the present invention. As the alignment film, for example, modified polyvinyl alcohol described in WO01/88574A1 and Japanese Patent No. 3907735 can be used. The alignment film is typically subjected to an alignment treatment. Typical examples of alignment treatment include rubbing treatment and photo-alignment treatment. Since the rubbing process is well known in the industry, detailed description is omitted. As the photo-aligned alignment film (photo-alignment film), for example, those described in WO2005/096041, trade name LPP-JP265CP manufactured by Rolic technologies, etc. can be used. The thickness of the alignment film is, for example, 0.01 μm to 10 μm, preferably 0.01 μm to 1 μm, more preferably 0.01 μm to 0.5 μm.

The anti-glare layer 32 can be formed, for example, by the following procedure. First, a coating liquid for forming an alignment film is applied onto the first substrate 31 and dried to form a coating film. The coating film is rubbed in a predetermined direction to form an alignment film on the first substrate 31 . The predetermined direction can correspond to the slow axis direction of the anti-glare layer 32 to be obtained. Next, a coating solution for forming an anti-glare layer (for example, a solution containing a liquid crystal compound and optionally a cross-linkable monomer) is applied onto the formed alignment film and heated. Heating removes the solvent of the coating liquid and advances the orientation of the liquid crystal compound. Heating may be carried out in one step, or may be carried out in multiple steps by changing the temperature. Next, the crosslinkable (or polymerizable) monomer is crosslinked (or polymerized) by UV irradiation to fix the orientation of the liquid crystal compound. In this manner, the anti-reflection layer 32 is formed on the first base material 31 (substantially, on the alignment film). A method for orienting a discotic liquid crystal compound is described, for example, in JP-A-2014-214177, and a method for orienting a rod-like liquid crystal compound is described, for example, in JP-A-2006-163343. The descriptions of these publications are incorporated herein by reference. The alignment film may be omitted depending on the desired alignment state, the type of liquid crystal compound, and the like.

C-2. First Substrate The first substrate 31 is used to form the anti-glare layer 32 .

Any appropriate resin film is used as the first base material 31 . Examples of resin film-forming materials include polyester resins such as polyethylene terephthalate (PET), cycloolefin resins such as norbornene resins, addition of cycloolefins (e.g., norbornene) and α-olefins (e.g., ethylene). Cellulosic resins such as resins obtained by polymerization (COC) and triacetyl cellulose (TAC) can be mentioned. In one embodiment of the present invention, the first substrate 31 contains TAC-based resin.

The thickness of the first base material 31 can be appropriately set according to the purpose. The thickness of the first base material 31 is typically 20 μm to 200 μm, preferably 25 μm to 100 μm, more preferably 30 μm to 50 μm.

D. Reinforcement Layer The reinforcement layer 5 provides the optical laminate 1 with excellent resistance to local loads. In one embodiment of the present invention, the reinforcing layer 5 is attached to the first base material 31 via the second adhesive layer 62 . The reinforcing layer 5 is arranged between the second adhesive layer 62 and the third adhesive layer 63 . The reinforcing layer 5 is in contact with the second adhesive layer 62 and the third adhesive layer 63 and is pressure-sensitively adhered to the second adhesive layer 62 and the third adhesive layer 63 .

The reinforcing layer 5 is made of any suitable film. Specific examples of the material that is the main component of the reinforcing layer 5 include, for example, the same material as the main component of the protective layer 22 described in section B-2 above (the above transparent resin, the above thermosetting resin, or UV curable resins, the glassy polymers described above, and the resin compositions described above). In one embodiment of the present invention, the reinforcing layer 5 contains a (meth)acrylic resin, preferably a (meth)acrylic resin having a glutarimide structure. That is, each of the protective layer 22 and the reinforcing layer 5 contains a (meth)acrylic resin. By using a (meth)acrylic resin for the protective layer 22 and the reinforcing layer 5 , it is possible to stably suppress light leakage when a load of a predetermined value or more is locally applied to the optical layered body 1 .

As with the protective layer 22, the reinforcing layer 5 may be subjected to the above-described surface treatment and/or the above-described treatment for improving visibility, if necessary.

The thickness of the reinforcing layer 5 is typically 20 μm to 70 μm, preferably 30 μm to 50 μm. If the thickness of the reinforcing layer is within such a range, the elastic modulus of the optical layered body can be suitably adjusted within the above range.

E. Second Optical Function Body The second optical function body 4 can provide the optical laminate 1 with an optical function different from that of the first optical function body 3 . Examples of the second optical function body 4 include an antireflection layered body and a layered body for sunglasses.
The thickness of the second optical function body 4 is typically 40 μm to 120 μm, preferably 70 μm to 100 μm or less.

In one embodiment of the invention, the second optical function body 4 is an antireflection laminate 4a. The antireflection laminate 4a includes a second substrate 41, a hard coat layer 42 arranged on the viewer side of the second substrate 41, and an antireflection layer 43 arranged on the viewer side of the hard coat layer 42. including. In other words, the antireflection laminate 4 a may consist of the second base material 41 , the hard coat layer 42 and the antireflection layer 43 . The second base material 41 is arranged on the viewing side with respect to the reinforcing layer 5 and is attached to the reinforcing layer 5 via the third adhesive layer 63 . The second substrate 41 is in contact with the third adhesive layer 63 and pressure-sensitively adhered to the third adhesive layer 63 . In one embodiment of the present invention, the hard coat layer 42 is formed directly on the surface of the second base material 41 on the viewing side. As used herein, "directly" means that there is no intervening adhesive layer or adhesive layer. In addition, the antireflection layer 43 is formed directly on the surface of the hard coat layer 42 on the viewing side.

E-1. Second Substrate The second substrate 41 is used to form the hard coat layer 42 and the antireflection layer 43 . Any appropriate resin film is used as the second base material 41 . As the material for forming the second base material 41, for example, the same material as the material for forming the first base material 31 described in section C-2 above (the above polyester resin, the above cycloolefin resin, the above resins obtained by addition polymerization of cycloolefins and α-olefins, and the cellulose-based resins described above). In one embodiment of the invention, the second base material 41 contains a TAC-based resin.

The thickness of the second base material 41 can be appropriately set according to the purpose. The thickness of the second base material 41 is typically 20 μm to 200 μm, preferably 50 μm to 150 μm, more preferably 70 μm to 90 μm.

E-2. Hard Coat Layer The hard coat layer 42 can impart excellent pencil hardness to the optical laminate 1 . Furthermore, by appropriately adjusting the refractive index difference between the hard coat layer 42 and the antireflection layer 43, the reflectance of the optical laminate 1 can be further reduced.

Hard coat layer 42 preferably has sufficient surface hardness, excellent mechanical strength, and excellent optical transparency. The hard coat layer 42 can be formed from any appropriate resin as long as it has such desired properties. Specific examples of resins include thermosetting resins, thermoplastic resins, ultraviolet curing resins, electron beam curing resins, and two-liquid mixed resins. Among the resins forming the hard coat layer 42, UV-curing resins are preferred. If the resin is an ultraviolet curable resin, the hard coat layer 42 can be formed with simple operation and high efficiency.

Specific examples of UV curable resins include polyester, acrylic, urethane, amide, silicone and epoxy UV curable resins. UV-curable resins include UV-curable monomers, oligomers, and polymers. Preferred UV-curable resins include resin compositions containing acrylic monomer or oligomer components having preferably 2 or more, more preferably 3 to 6, UV-polymerizable functional groups. Typically, the UV curable resin contains a photopolymerization initiator.

Hard coat layer 42 may be formed by any appropriate method. For example, the hard coat layer 42 can be formed by coating a resin composition for forming a hard coat layer on the second base material 41, drying it, and curing the dried coating film by irradiating it with ultraviolet rays. .

The thickness of the hard coat layer 42 is, for example, 0.5 μm to 20 μm, preferably 1 μm to 15 μm.

Details of the hard coat layer and the adhesion structure between the hard coat layer and the antireflection layer are described in, for example, JP-A-2016-224443. The description of the publication is incorporated herein by reference.

E-3. Antireflection Layer The antireflection layer 43 is provided to prevent reflection of external light (for example, fluorescent light). Any appropriate configuration can be adopted as the configuration of the antireflection layer 43 . A typical configuration of the antireflection layer 43 includes (1) a single layer of a low refractive index layer having an optical thickness of 120 nm to 140 nm and a refractive index of about 1.35 to 1.55; (3) Alternating multi-layer laminate of high refractive index layers and low refractive index layers;

Materials that can form the low refractive index layer include, for example, silicon oxide (SiO ₂ ) and magnesium fluoride (MgF ₂ ). The refractive index of the low refractive index layer is typically about 1.35 to 1.55. Materials capable of forming the high refractive index layer include, for example, titanium oxide (TiO ₂ ), niobium oxide (Nb ₂ O ₃ or Nb ₂ O ₅ ), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), ZrO ₂ —TiO ₂ can be mentioned. The refractive index of the high refractive index layer is typically about 1.60 to 2.20. Materials capable of forming the medium refractive index layer include, for example, titanium oxide (TiO ₂ ), a mixture of a material capable of forming a low refractive index layer and a material capable of forming a high refractive index layer (for example, titanium oxide and oxide mixtures with silicon). The refractive index of the medium refractive index layer is typically about 1.50 to 1.85. The thicknesses of the low refractive index layer, the medium refractive index layer, and the high refractive index layer can be set so as to realize an appropriate optical film thickness according to the layer structure of the antireflection layer, desired antireflection performance, and the like.

Antireflection layer 43 is typically formed by a dry process. Specific examples of the dry process include a PVD (Physical Vapor Deposition) method and a CVD (Chemical Vapor Deposition) method. PVD methods include a vacuum deposition method, a reactive deposition method, an ion beam assist method, a sputtering method, and an ion plating method. As the CVD method, there is a plasma CVD method. A dry process for forming the antireflection layer 43 is preferably a sputtering method.

The thickness of the antireflection layer 43 is, for example, about 20 nm to 300 nm.

In the antireflection layer 43, the difference between the maximum reflectance and the minimum reflectance in the wavelength range of 400 nm to 700 nm is preferably 2.0% or less, more preferably 1.9% or less, and still more preferably 1.0%. 8% or less. If the difference between the maximum reflectance and the minimum reflectance is in such a range, it is possible to satisfactorily prevent the coloring of the reflected light.

In one embodiment of the present invention, the antireflection layer 43 is located on the outermost surface of the optical laminate 1 on the viewing side. The moisture permeability of the antireflection layer 43 is typically 1.0 g/mm ² or less, preferably 0.1 g/mm ² or less, and typically 0.01 g/mm ² or more. The water vapor permeability is measured in accordance with the JIS Z0208 water vapor permeability test (cup method) as the amount of water vapor (g) that passes through a ¹ m2 sample in 24 hours in an atmosphere with a temperature of 40°C and a humidity of 92% RH. can be measured. If the moisture permeability of the antireflection layer 43 located on the outermost surface is equal to or less than the above upper limit, warping of the optical layered body 1 in a high-humidity environment can be stably suppressed.

Note that the antireflection layer 43 does not have to be positioned on the outermost surface of the optical layered body 1 . The antireflection laminate 4a may have an outermost layer on the viewing side of the antireflection layer 43, if necessary. That is, the antireflection laminate 4a may consist of the second substrate 41, the hard coat layer 42, the antireflection layer 43, and the outermost layer. The range of moisture permeability of the outermost surface layer is the same as the range of moisture permeability of the antireflection layer 43 described above. Examples of the outermost layer include an antifouling layer. The antifouling layer contains, for example, a fluorine group-containing silane compound (for example, an alkoxysilane compound having a perfluoropolyether group) or a fluorine group-containing organic compound. The antifouling layer preferably exhibits water repellency with a water contact angle of 110 degrees or more.

F. First adhesive layer, second adhesive layer, and third adhesive layer Each of the first adhesive layer 61, the second adhesive layer 62, and the third adhesive layer 63 contains an adhesive ( pressure sensitive adhesive). More specifically, the first adhesive layer 61 is formed by applying an adhesive to the protective layer 22 of the polarizing plate 2 so as to have the thickness described above. The second adhesive layer 62 is formed by applying an adhesive on the first substrate 31 of the first optical function body 3 so as to have the thickness described above. The third adhesive layer 63 is formed by applying an adhesive onto the reinforcing layer 5 so as to have the thickness described above. The first adhesive layer 61, the second adhesive layer 62, and the third adhesive layer 63 may be formed from the same adhesive, or may be formed from different adhesives. In one embodiment of the present invention, first adhesive layer 61, second adhesive layer 62 and third adhesive layer 63 are formed from the same adhesive. When the first pressure-sensitive adhesive layer 61, the second pressure-sensitive adhesive layer 62 and the third pressure-sensitive adhesive layer 63 are formed from the same pressure-sensitive adhesive, the manufacturing cost of the optical laminate 1 can be reduced.

The adhesive typically contains a (meth)acrylic polymer, urethane polymer, silicone polymer or rubber polymer as a base polymer. When a (meth)acrylic polymer is used as the base polymer, the adhesive layer is formed from, for example, an adhesive containing the (meth)acrylic polymer.

F-1. (Meth)acrylic polymer The (meth)acrylic polymer contains a polymer of monomer components (raw material monomers) having alkyl (meth)acrylate as a main component. In other words, the (meth)acrylic polymer contains structural units derived from alkyl (meth)acrylates. Alkyl (meth)acrylate is preferably 50% by weight or more in all monomer components that are raw materials of the (meth)acrylic polymer, and can be arbitrarily set as the balance of monomers other than the alkyl (meth)acrylate. (Meth)acrylate refers to acrylate and/or methacrylate.

Alkyl (meth)acrylates constituting the main skeleton of the (meth)acrylic polymer include linear or branched alkyl groups having 1 to 18 carbon atoms. Examples of alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, amyl group, hexyl group, cyclohexyl group, heptyl group, 2-ethylhexyl group, isooctyl group, nonyl group and decyl group. , isodecyl group, dodecyl group, isomyristyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like. Alkyl (meth)acrylates can be used alone or in combination. The average carbon number of the alkyl group is preferably 3-10.

The (meth)acrylic polymer may contain a structural unit derived from a copolymerizable monomer polymerizable with the alkyl (meth)acrylate, in addition to the structural unit derived from the alkyl (meth)acrylate. That is, the monomer component that is the raw material of the (meth)acrylic polymer can further contain a copolymerizable monomer in addition to the alkyl (meth)acrylate.

Examples of copolymerizable monomers include carboxyl group-containing monomers, hydroxyl group-containing monomers, amino group-containing monomers, amide group-containing monomers, cyclization polymerizable monomers, epoxy group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, Polyfunctional acrylates, (meth)acrylic acid esters having an alicyclic hydrocarbon group, (meth)acrylic acid esters having an aromatic hydrocarbon group, vinyl esters, aromatic vinyl compounds, dienes, vinyl ethers, vinyl chloride etc. Comonomers can be used alone or in combination.

Among such copolymerizable monomers, preferred are reactive group-containing monomers containing a reactive group capable of reacting with the cross-linking agent described later, and more preferred are carboxyl group-containing monomers and hydroxyl group-containing monomers. mentioned. The reactive group-containing monomer becomes a reaction point with the cross-linking agent when the pressure-sensitive adhesive contains the cross-linking agent described below. Carboxyl group-containing monomers and hydroxyl group-containing monomers are highly reactive with intermolecular cross-linking agents, and are therefore preferably used to improve cohesiveness and heat resistance of the pressure-sensitive adhesive layer to be obtained. A carboxyl group-containing monomer is preferable in terms of achieving both durability and reworkability, and a hydroxyl group-containing monomer is preferable in terms of improving reworkability. The copolymerizable monomers can be used singly or in combination as raw material monomers for the (meth)acrylic polymer.

A carboxyl group-containing monomer is a compound containing a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of carboxyl group-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Among these, acrylic acid is preferred. The (meth)acrylic polymer may preferably contain a structural unit derived from a carboxyl group-containing monomer, more preferably a structural unit derived from (meth)acrylic acid. When the (meth)acrylic polymer contains a structural unit derived from a carboxyl group-containing monomer, the adhesive properties of the adhesive layer can be improved.

When a carboxyl group-containing monomer is used as a raw material monomer, the content of the carboxyl group-containing monomer is usually 0.01% by weight or more and 10% by weight or less in all monomer components that are raw materials for the (meth)acrylic polymer.

A hydroxyl group-containing monomer is a compound containing a hydroxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group and a vinyl group. Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl ( hydroxyalkyl (meth)acrylates such as meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate; (4-hydroxymethylcyclohexyl)-methyl acrylate and the like. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is more preferred. The (meth)acrylic polymer may preferably contain structural units derived from hydroxyl group-containing monomers, more preferably structural units derived from 2-hydroxyethyl (meth)acrylate and/or 4-hydroxybutyl (meth)acrylate. When the (meth)acrylic polymer contains a structural unit derived from a hydroxyl group-containing monomer, the durability of the pressure-sensitive adhesive layer can be improved.

When a hydroxyl group-containing monomer is used as a raw material monomer, the content of the hydroxyl group-containing monomer is usually 0.01% by weight or more and 10% by weight or less in all monomer components that are raw materials for the (meth)acrylic polymer.

The (meth)acrylic polymer has a weight average molecular weight Mw of, for example, 200,000 to 3,000,000, preferably 1,000,000 to 2,500,000, and more preferably 1,200,000 to 2,500,000. If the weight-average molecular weight Mw is within such a range, a pressure-sensitive adhesive layer with excellent durability (especially heat resistance) can be obtained. If the weight average molecular weight Mw exceeds 3,000,000, viscosity increase and/or gelation during polymer polymerization may occur.

F-2. Cross-linking agent The adhesive can contain a cross-linking agent. As the cross-linking agent, an organic cross-linking agent, a polyfunctional metal chelate, or the like can be used. Examples of organic cross-linking agents include isocyanate-based cross-linking agents, peroxide-based cross-linking agents, epoxy-based cross-linking agents, and imine-based cross-linking agents. Polyfunctional metal chelates are those in which polyvalent metals are covalently or coordinately bonded to organic compounds. When the adhesive is radiation-curable, a polyfunctional monomer can be used as a cross-linking agent. Cross-linking agents can be used alone or in combination. The cross-linking agent preferably includes an isocyanate-based cross-linking agent and a peroxide-based cross-linking agent.

When a cross-linking agent is added to the adhesive, the amount of the cross-linking agent is usually 0.01 to 15 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer (base polymer). When an isocyanate-based cross-linking agent is blended in the adhesive, the amount of the isocyanate-based cross-linking agent is usually 0.01 to 15 parts by weight, preferably 1 part by weight, per 100 parts by weight of the (meth)acrylic polymer. 0 to 10 parts by weight, more preferably 2.5 to 5 parts by weight. When a peroxide cross-linking agent is added to the adhesive, the amount of the peroxide cross-linking agent is usually 0.01 to 2 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer. , preferably 0.1 to 0.5 parts by weight. When the blending ratio of the cross-linking agents (isocyanate-based cross-linking agent and peroxide-based cross-linking agent) is within the above range, when a reactive group-containing monomer is included in the raw material monomer component of the (meth)acrylic polymer, it will be described later. The elastic modulus of the pressure-sensitive adhesive layer can be smoothly adjusted within a desired range.

F-3. Reactive Functional Group-Containing Silane Coupling Agent The adhesive may contain a reactive functional group-containing silane coupling agent. In the reactive functional group-containing silane coupling agent, the reactive functional group is typically a functional group other than an acid anhydride group. Examples of functional groups other than acid anhydride groups include epoxy group, mercapto group, amino group, isocyanate group, isocyanurate group, vinyl group, styryl group, acetoacetyl group, ureido group, thiourea group, and (meth)acrylic group. , heterocyclic groups, and combinations thereof. Silane coupling agents containing reactive functional groups can be used alone or in combination.

When blending a reactive functional group-containing silane coupling agent in the adhesive, the amount of the reactive functional group-containing silane coupling agent is usually 0.001 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer. 5 parts by weight or less.

F-4. Additive The adhesive may contain a (meth)acrylic oligomer and/or an ionic compound. Moreover, the adhesive may contain an additive. Specific examples of additives include powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light Stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, and foils can be used. Also, a redox system with a reducing agent added may be employed within a controllable range. Also, the adhesive may contain a polyether compound having a reactive group (for example, a reactive silyl group). The type, number, combination, content, etc. of additives can be appropriately set according to the purpose. The content of the additive is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and still more preferably 1 part by weight or less with respect to 100 parts by weight of the (meth)acrylic polymer.

F-5. Properties of Adhesive The storage modulus of the adhesive at 23° C. and 55% RH is typically 0.05 GPa or more, preferably 0.11 GPa or more, and typically 0.2 GPa or less, preferably 0.15 GPa or less. is. The storage modulus can be measured according to JIS K 7244 using a dynamic viscoelasticity measuring device "ARES" manufactured by Rheometric. If the elastic modulus of the adhesive is within such a range, the elastic modulus of the optical layered body 1 can be stably adjusted within the above range.

G. First Retardation Layer The first retardation layer 7 may be composed of a retardation film having any appropriate optical properties and/or mechanical properties depending on the purpose. The first retardation layer 7 is located on the opposite side of the polarizing plate 2 to the viewing side. The first retardation layer 7 is typically attached to the opposite side of the polarizer 21 from the viewing side via any appropriate adhesive layer. The thickness of the adhesive layer is typically 0.5 μm to 2.5 μm. The first retardation layer 7 may also serve as a protective layer on the side opposite to the viewing side of the polarizer 21 .

The thickness of the first retardation layer 7 is preferably 10 μm to 60 μm, more preferably 30 μm to 50 μm.

The in-plane retardation Re(550) of the first retardation layer 7 is preferably 80 nm to 150 nm, more preferably 90 nm to 140 nm, still more preferably 100 nm to 130 nm.

As described above, the first retardation layer 7 preferably exhibits a refractive index characteristic of nx>ny>nz. The Nz coefficient of the first retardation layer 7 is preferably 1.1-3.0, more preferably 1.3-2.7.

The first retardation layer 7 may preferably be arranged such that its slow axis is substantially parallel to the absorption axis of the polarizer 21 . As used herein, the expressions “substantially parallel” and “substantially parallel” include cases in which the angle formed by two directions is 0°±7°, preferably 0°±5°, more preferably is 0°±3°. The expressions "substantially orthogonal" and "substantially orthogonal" include the case where the angle formed by the two directions is 90°±7°, preferably 90°±5°, more preferably 90°± 3°. Further, references herein to simply "orthogonal" or "parallel" are intended to include substantially orthogonal or substantially parallel states.

The absolute value of the photoelastic coefficient of the first retardation layer 7 is preferably 2×10 ⁻¹¹ m ² /N or less, more preferably 2.0×10 ⁻¹³ m ^{2 /} N to 1.5×10 ^{− 11} m ² /N, more preferably 1.0×10 ⁻¹² m ^{2 /} N to 1.2× ^{10 −11} m ² /N of resin. If the absolute value of the photoelastic coefficient is within such a range, the phase difference is less likely to change when shrinkage stress occurs during heating. Therefore, by forming the first retardation layer using a resin having such an absolute value of photoelastic coefficient, heat unevenness can be satisfactorily prevented when the optical layered body is applied to an image display device.

The first retardation layer 7 may exhibit a reverse wavelength dispersion characteristic in which the retardation value increases according to the wavelength of the measurement light, or a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. and a flat wavelength dispersion characteristic in which the retardation value hardly changes even with the wavelength of the measurement light. The first retardation layer 7 preferably exhibits flat wavelength dispersion characteristics. Specifically, Re(450)/Re(550) of the first retardation layer 7 is preferably 0.99 to 1.03, and Re(650)/Re(550) is preferably 0.98. ~1.02. By arranging a λ / 2 plate (first retardation layer) and a λ / 4 plate (second retardation layer) having flat wavelength dispersion characteristics at a predetermined axis angle, ideal reverse wavelength dispersion It is possible to obtain characteristics close to the characteristics, and as a result, very excellent antireflection characteristics can be realized.

The first retardation layer 7 may be composed of any suitable resin film that can satisfy the properties as described above. Representative examples of such resins include cyclic olefin-based resins, polycarbonate-based resins, cellulose-based resins, polyester-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic resins. system resin. Among them, cyclic olefin resins can be preferably used. The first retardation layer 7 is obtained, for example, by stretching a film formed from the above resin. Details of the cyclic olefin resin and the stretching method of the resin film (method of forming the retardation film) are described in, for example, JP-A-2015-210459 and JP-A-2016-105166. The description of this publication is incorporated herein by reference.

H. Second Retardation Layer The second retardation layer 8 may be composed of a retardation film having any appropriate optical properties and/or mechanical properties depending on the purpose. The second retardation layer 8 is located on the side opposite to the viewing side of the first retardation layer 7 . The second retardation layer 8 is typically attached to the side opposite to the viewing side of the first retardation layer 7 via any appropriate adhesive layer. The thickness of the adhesive layer is typically 0.5 μm to 2.5 μm.

The thickness of the second retardation layer 8 is preferably 10 μm to 50 μm, most preferably 20 μm to 40 μm.

The in-plane retardation Re(550) of the second retardation layer 8 is preferably 10 nm to 60 nm, more preferably 20 nm to 50 nm, still more preferably 30 nm to 40 nm.

As described above, the second retardation layer 8 preferably exhibits a refractive index characteristic of nz>nx>ny. The Nz coefficient of the second retardation layer 8 is preferably -10 to -0.1, more preferably -5 to -1.

The second retardation layer 8 can preferably be arranged such that its slow axis is substantially orthogonal to the absorption axis of the polarizer 21 .

The second retardation layer 8 may be composed of any suitable resin film that can satisfy the properties as described above. Such resins can typically be polymers with negative intrinsic birefringence. A polymer having negative intrinsic birefringence refers to a polymer whose refractive index in the orientation direction is relatively small when the polymer is oriented by stretching or the like. Examples of polymers having negative intrinsic birefringence include those in which a chemical bond or functional group with large polarization anisotropy such as an aromatic group or a carbonyl group is introduced into the side chain of the polymer. Specific examples include modified polyolefin-based resins (eg, modified polyethylene-based resins), acrylic resins, styrene-based resins, maleimide-based resins, fumarate-based resins, and the like. The second retardation layer 8 can be obtained, for example, by appropriately stretching a film formed from the above resin.

Note that in one embodiment of the present invention, the optical stack 1 includes the first retardation layer 7 and the second retardation layer 8, but the optical stack includes the first retardation layer and/or the second retardation layer No retardation layer may be provided.

I. Fourth Adhesive Layer The fourth adhesive layer 9 is arranged on the side opposite to the viewing side of the second retardation layer 8 . The fourth adhesive layer 9 is formed from an adhesive (pressure-sensitive adhesive). More specifically, the fourth pressure-sensitive adhesive layer 9 is formed by applying a pressure-sensitive adhesive onto the second retardation layer 8 so as to have the thickness described above. The pressure-sensitive adhesive is as described in section F above regarding the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer. The fourth adhesive layer 9 may be formed from the same adhesive as the first to third adhesive layers, or may be formed from a different adhesive.

J. Image Display Device The optical layered body according to the above items A to I can be applied to an image display device. Therefore, one embodiment of the present invention also includes an image display device using such an optical laminate. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes the optical layered body described in items A to I above on the viewing side thereof. The image display device includes an image display panel. The image display panel includes image display cells. An image display device may be called an optical display device, an image display panel may be called an optical display panel, and an image display cell may be called an optical display cell.

In the image display device, the optical layered body 1 described above is attached to the image display panel with the fourth pressure-sensitive adhesive layer 9 . More specifically, a common method is to attach the polarizing plate to a rotating body such as a drum roll and attach it to the transported panel with high accuracy.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. In addition, the measuring method of each characteristic is as follows.

(1) Orange Peel The optical laminates obtained in Examples and Comparative Examples were cut into 200 mm×300 mm sizes to obtain test samples. In the test sample, the absorption axis direction (MD direction) of the polarizer was parallel to the width direction (direction orthogonal to the longitudinal direction) of the test sample. Then, the test sample was attached to a black acrylic plate with a fourth adhesive layer. Light is incident on the surface of the visible side of the test sample attached to the acrylic plate using a fluorescent lamp so that the reflection angle is 45 ° to 70 °, and the appearance of the test sample (surface on the visible side) was visually observed. The results were evaluated according to the following criteria.
A: Inconspicuous unevenness B: Noticeable unevenness C: Remarkably noticeable unevenness (2) Air bubbles glued to the glass. The interface between the fourth pressure-sensitive adhesive layer of the optical laminate and the alkali-free glass was observed with a microscope. Then, the generation of air bubbles was evaluated according to the following criteria.
A: After bonding the optical laminate to the non-alkali glass, there are no air bubbles between the fourth pressure-sensitive adhesive layer and the non-alkali glass.
B: Air bubbles are present between the fourth pressure-sensitive adhesive layer and the alkali-free glass after the optical laminate is attached to the alkali-free glass.
(3) Modulus of Elasticity The optical laminates obtained in Examples and Comparative Examples were cut into 25 mm×150 mm size (specimen type 2 according to JIS K 7127) to obtain test samples. The elastic modulus (tensile properties) of the test sample was measured by a measuring method based on JIS K 7127 using an autograph manufactured by Shimadzu Corporation.
(4) Evaluation of unevenness on the surface of the fourth adhesive layer The surface of the fourth adhesive of the optical laminates obtained in Examples and Comparative Examples was exposed, and the surface was subjected to unevenness using New view 7300 manufactured by Zygo. was measured.

[Examples 1 and 2]
1. Preparation of Polarizing Plate (Polarizer Laminate) As a thermoplastic resin substrate, a long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used. was corona-treated on one side.
Polyvinyl alcohol (degree of polymerization: 4,200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER") were mixed at a ratio of 9:1, and 100 parts by weight of PVA-based resin. was added with 13 parts by weight of potassium iodide and dissolved in water to prepare an aqueous PVA solution (coating solution).
The above PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.
The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment).
Then, the finally obtained polarizer is added to a dyeing bath (iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. It was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) was a desired value (dyeing treatment).
Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 40°C (an aqueous solution of boric acid obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water). (crosslinking treatment).
After that, while immersing the laminate in an aqueous solution of boric acid (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70° C., the laminate was moved vertically (longitudinally) between rolls with different peripheral speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
After that, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment).
Thereafter, while drying in an oven maintained at about 90° C., it was brought into contact with a heating roll made of SUS whose surface temperature was maintained at about 75° C. (dry shrinkage treatment).
Thus, a polarizer having a thickness of about 5 μm was formed on the resin substrate.
An acrylic resin film (thickness: 40 μm) having a glutarimide structure as a protective layer was attached to the surface of the obtained polarizer (the surface opposite to the resin substrate) via an ultraviolet curable adhesive. rice field. Specifically, the curable adhesive was applied so as to have a total thickness of about 2.0 μm, and was bonded using a roll machine. After that, UV rays were irradiated from the acrylic resin film side to cure the adhesive. Then, the resin substrate was peeled off to obtain a polarizing plate having a structure of acrylic resin film (protective layer)/polarizer.
Next, a surface protective film having through holes was attached to the surface of the polarizer (the surface opposite to the protective layer) to obtain a laminate having a structure of protective layer/polarizer/surface protective film. After that, the laminate was immersed in an aqueous NaOH solution (basic solution) to bring the polarizer exposed from the through holes into contact with the basic solution. As a result, the portion of the polarizer in contact with the basic solution was decolorized to form a non-polarized portion.
Next, after the laminate was purely immersed and washed, the laminate was immersed in a H ₂ SO ₄ aqueous solution (acidic solution) and then purely immersed and washed. After that, the surface protective film was peeled off from the polarizer and removed.
As described above, a polarizing plate including a polarizer having a non-polarizing portion was obtained. The thickness of the non-polarizing portion was 4.5 μm. Further, the surface of the polarizer on the side opposite to the protective layer had a concave portion corresponding to the non-polarized portion, while the surface of the polarizer on the side of the protective layer was substantially flat.

2. Anti-Reflection Laminate As the anti-reflection laminate, a TAC film with a retardation layer manufactured by FUJIFILM Corporation (product name: HL214, thickness: 42 μm) was used.

3. Preparation of Antireflection Laminate As an antireflection laminate, an AR film (AR+HC thickness: 4 μm, substrate thickness: 80 μm) manufactured by Dexerials Corporation was used.

4. Preparation of adhesive 4-1. Preparation of adhesive PSA1 used in the first to fourth adhesive layers 94.9 parts of butyl acrylate, 94.9 parts of butyl acrylate, A monomer mixture containing 0.1 part 4-hydroxybutyl acrylate and 5.0 parts acrylic acid was charged. Further, 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts of this monomer mixture together with 100 parts of ethyl acetate, and nitrogen gas was introduced while gently stirring. After the replacement, the liquid temperature in the flask was maintained at around 55° C., and the polymerization reaction was carried out for 8 hours to prepare a solution of acrylic polymer A1 having a weight average molecular weight (Mw) of 2,200,000 and Mw/Mn=3.0. .
To 100 parts of the solid content of the acrylic polymer A1 solution, 3 parts of a trimethylolpropane/tolylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Coronate L") and 0.5 parts of a peroxide cross-linking agent (benzoyl peroxide). 2 parts, 0.075 parts of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403"), and a polyether compound having a reactive silyl group (manufactured by Kaneka, trade name "Silyl SAT10") was blended to obtain a pressure-sensitive adhesive PSA1. The storage modulus of the adhesive constituting the adhesive layer was measured based on JIS K 7244 using a dynamic viscoelasticity measuring device "ARES" manufactured by Rheometric. The storage modulus of PSA1 at 23°C and 55% RH was 0.11 GPa.

5. Preparation of Optical Laminate A glare-preventing laminate was attached to the protective layer of the polarizing plate via the adhesive PSA1. Specifically, the adhesive PSA1 was applied to the surface of the protective layer on the viewing side to form a first adhesive layer having the thickness shown in Table 1, and then the anti-glare laminate was formed. The layers were brought into contact with the first pressure-sensitive adhesive layer, and the reflection-preventing laminate was attached to the polarizing plate via the first pressure-sensitive adhesive layer. At this time, adjustment was made so that the slow axis of the glare-preventing layer (orientation-fixed layer of the liquid crystal compound) formed an angle of 45° with respect to the absorption axis of the polarizer.
Next, an acrylic resin film (thickness: 40 μm) having a glutarimide structure was laminated as a reinforcing layer onto the first base material of the anti-glare laminate via an adhesive PSA1. Specifically, the pressure-sensitive adhesive PSA1 is applied to the surface of the first base material on the viewing side to form a second pressure-sensitive adhesive layer having a thickness shown in Table 1, and the reinforcing layer is formed of the second pressure-sensitive adhesive. It was brought into contact with the layer and attached to the anti-reflection laminate.
Next, an antireflection laminate was laminated on the reinforcing layer with an adhesive PSA1 interposed therebetween. Specifically, the pressure-sensitive adhesive PSA1 is applied to the surface of the reinforcing layer on the viewing side to form a third pressure-sensitive adhesive layer having the thickness shown in Table 1, and then the second base of the antireflection laminate is formed. The material was brought into contact with the second adhesive layer, and the antireflection laminate was laminated to the reinforcing layer via the third adhesive layer.
Further, a cyclic olefin-based film (refractive index characteristics: nx>ny>nz, in-plane retardation: 116 nm) as a first retardation layer is applied to the surface of the polarizer opposite to the protective layer with an ultraviolet curable adhesive. A layer (thickness: 1.0 µm) was interposed between them. At this time, the slow axis of the first retardation layer was adjusted to form an angle of 0° with respect to the absorption axis of the polarizer. After that, a modified polyethylene film (refractive index characteristics: nz>nx>ny, in-plane retardation: 35 nm) is applied as a second retardation layer to the surface of the first retardation layer opposite to the polarizer, and a UV-curing type They were bonded via an adhesive layer (thickness 1.0 μm). At this time, the slow axis of the second retardation layer was adjusted to form an angle of 90° with respect to the absorption axis of the polarizer.
Then, the pressure-sensitive adhesive PSA1 was applied to the surface of the second retardation layer opposite to the first retardation layer to form a fourth pressure-sensitive adhesive layer having the thickness shown in Table 1.
By the above, the antireflection laminate/third adhesive layer/reinforcing layer/second adhesive layer/anti-reflection laminate/first adhesive layer/polarizing plate/first retardation layer/second was obtained. Table 1 shows the thickness of each layer included in the optical layered body, the total thickness of the optical layered body, and the total thickness of the anti-reflection layered body, the reinforcing layer, and the antireflection layered body. The optical layered body was also evaluated for the orange peel, the air bubbles, the elastic modulus, and the unevenness of the surface of the fourth pressure-sensitive adhesive layer. The results are shown in Table 2 together with the thickness of each adhesive layer.

[Comparative Examples 1 to 4]
The anti-reflection laminate is attached to the anti-reflection laminate via the second adhesive layer without providing a reinforcing layer between the anti-reflection laminate and the anti-reflection laminate, and each adhesive Antireflection laminate/second adhesive layer/anti-glare laminate/first adhesive layer in the same manner as in Example 1, except that the layer thicknesses were changed to the values shown in Tables 1 and 2. An optical laminate having a structure of /polarizing plate/first retardation layer/second retardation layer/fourth pressure-sensitive adhesive layer was obtained.

[evaluation]
As is clear from Table 2, by setting the thickness of each pressure-sensitive adhesive layer to 17 μm or less and providing a reinforcing layer between the anti-reflection laminate and the anti-reflection laminate, orange peel can be suppressed while the optical laminate can be is attached to the image display panel, an optical layered body can be obtained in which air bubbles can be suppressed from entering between the optical layered body and the display panel.

The optical laminate of the present invention can be suitably used for image display devices (typically, liquid crystal display devices and organic EL display devices).

REFERENCE SIGNS LIST 1 optical laminate 2 polarizing plate 21a non-polarizing portion 3 reflection prevention laminate 4 antireflection laminate 5 reinforcing layer 61 first adhesive layer 62 second adhesive layer 63 third adhesive layer 7 first adhesive layer Retardation layer 8 Second retardation layer 9 Fourth adhesive layer

Claims (6)

a polarizing plate including a non-polarizing portion;
a first optical function body bonded to the polarizing plate via a first pressure-sensitive adhesive layer;
a reinforcing layer located on the opposite side of the polarizing plate with respect to the first optical function body and bonded to the first optical function body via a second adhesive layer;
a second optical function body located on the side opposite to the first optical function body with respect to the reinforcement layer and bonded to the reinforcement layer via a third adhesive layer ;
a fourth adhesive layer located on the opposite side of the first optical function body with respect to the polarizing plate,
The optical laminate, wherein each thickness of the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer, the third pressure-sensitive adhesive layer and the fourth pressure-sensitive adhesive layer is 17 μm or less. 2. The optical laminate according to claim 1, which has an elastic modulus of 2700 MPa or more. The thickness of each of the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer is the thickness of the fourth pressure-sensitive adhesive layer or less, according to claim 1 or 2. Optical laminate. The optical laminate according to any one of claims 1 to 3, wherein the sum of the thickness of the first optical function body, the thickness of the reinforcing layer, and the thickness of the second optical function body is 200 µm or less. body. The optical laminate according to any one of claims 1 to 4, wherein the surface of the fourth pressure-sensitive adhesive layer opposite to the polarizing plate has unevenness of 0.5 µm or more and 1.0 µm or less. a first retardation layer positioned on the opposite side of the first optical function body with respect to the polarizing plate and attached to the polarizing plate;
A second retardation layer located on the opposite side of the polarizing plate with respect to the first retardation layer and attached to the first retardation layer,
The fourth pressure-sensitive adhesive layer is arranged on the opposite side of the first retardation layer with respect to the second retardation layer ,
The first retardation layer exhibits refractive index characteristics of nx>ny>nz,
The optical laminate according to any one of claims 1 to 5, wherein the second retardation layer exhibits refractive index characteristics of nz>nx>ny.

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