JP2022190399A - Optical laminate, polarizing plate, and image display device - Google Patents

Abstract

To provide an optical laminate which can suppress degradation of adhesion and change of transmission image sharpness after a light resistance test.SOLUTION: An optical laminate has a first resin layer and a second resin layer on a base material, wherein the first resin layer has an area α1 and an area α2 surrounding the α1 independent of each other, the second resin layer has an area β1 and an area β2 surrounding the area β1 independent of each other, and satisfies the following conditions 1 and 2. 1. θa1 indicating an average inclination angle on the surface on the resin layer side of the base material, and θa2 indicating an average inclination angle on the surface on the second resin layer side of the first resin layer have a relation of θa2<θa1. 2. Pa1 indicating an arithmetic average height on the surface on the resin layer side of the base material and Pa2 indicating an arithmetic average height on the surface of the second resin layer side of the first resin layer have a relation of Pa2<Pa1.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an optical layered body, a polarizing plate, and an image display device.

2. Description of the Related Art Optical laminates are sometimes installed on the surfaces of image display devices such as televisions, notebook PCs, and desktop PC monitors in order to impart antifouling properties, antireflection properties, antiglare properties, and the like.

An optical layered body consists of the basic composition which has an optical function layer on a base material. Since the optical layered body is often used as a surface member of an image display device and the like, there are many opportunities for contact with a person's finger, an object, or the like. Therefore, it is preferable that the optical layered body has good pencil hardness.

In order to improve the pencil hardness of the optical layered body, a cured product of a curable resin composition is preferably used as the binder resin for the optical functional layer.
The cured product of the curable resin composition tends to improve the pencil hardness of the optical layered body, but tends to be inferior in adhesion to the substrate. Patent Literatures 1 and 2 propose an optical layered body using a cured product of a curable resin composition as a binder resin for an optical functional layer and having good adhesion.

JP 2012-234163 A JP 2015-188772 A

The optical layered bodies of Patent Documents 1 and 2 have good initial adhesion. However, the optical layered bodies of Patent Documents 1 and 2 sometimes deteriorated in adhesion or changed in optical properties over time. Specifically, when the optical layered bodies of Patent Documents 1 and 2 were subjected to a light resistance test by ultraviolet irradiation, there were cases where the adhesion was lowered and the transmission image clarity was changed.

An object of the present disclosure is to provide an optical layered body, a polarizing plate and an image display device using the same, which can suppress a decrease in adhesion and a change in transmission image definition after a light resistance test. .

The present disclosure provides the following optical laminates, polarizing plates, and image display devices of [1] to [3].
[1] An optical laminate having a resin layer on a substrate,
The resin layer has a first resin layer and a second resin layer from the substrate side,
The first resin layer has a region α1 independent of each other and a region α2 surrounding the region α1, and the resin contained in the region α1 and the resin contained in the region α2 are different,
The second resin layer has a region β1 independent of each other and a region β2 surrounding the region β1, and the resin contained in the region β1 and the resin contained in the region β2 are different,
An optical laminate that satisfies condition 1 or condition 2 below.
<Condition 1>
θa1 indicating the average inclination angle of the surface of the base material facing the resin layer and θa2 indicating the average inclination angle of the surface of the first resin layer facing the second resin layer have a relationship of θa2<θa1. is.
<Condition 2>
Pa1 indicating the arithmetic mean height of the surface of the base material on the resin layer side and Pa2 indicating the arithmetic mean height of the surface of the first resin layer on the second resin layer side satisfy Pa2<Pa1 is the relationship.
[2] A polarizing plate having a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer. A polarizing plate, wherein at least one of the first transparent protective plate and the second transparent protective plate is the optical laminate according to [1].
[3] An image display device comprising the optical layered body according to [1] on a display element.

The optical layered body, the polarizing plate, and the image display device of the present disclosure can suppress a decrease in adhesion and a change in transmission image definition after a light resistance test.

1 is a cross-sectional view showing an embodiment of an optical laminate of the present disclosure; FIG. It is a figure explaining the method of calculating the position of area|region (alpha)1 in the thickness direction of a 1st resin layer. 1 is a cross-sectional view showing an embodiment of an image display device of the present disclosure; FIG.

Embodiments of the present disclosure will be described below.
[Optical laminate]
The optical laminate of the present disclosure has a resin layer on a substrate,
The resin layer has a first resin layer and a second resin layer from the substrate side,
The first resin layer has a region α1 independent of each other and a region α2 surrounding the region α1, and the resin contained in the region α1 and the resin contained in the region α2 are different,
The second resin layer has a region β1 independent of each other and a region β2 surrounding the region β1, and the resin contained in the region β1 and the resin contained in the region β2 are different,
It satisfies the following condition 1 or condition 2.
<Condition 1>
θa1 indicating the average inclination angle of the surface of the base material facing the resin layer and θa2 indicating the average inclination angle of the surface of the first resin layer facing the second resin layer have a relationship of θa2<θa1. is.
<Condition 2>
Pa1 indicating the arithmetic mean height of the surface of the base material on the resin layer side and Pa2 indicating the arithmetic mean height of the surface of the first resin layer on the second resin layer side satisfy Pa2<Pa1 is the relationship.

FIG. 1 is a cross-sectional view showing one embodiment of an optical laminate 100 of the present disclosure.
The optical layered body 100 of FIG. 1 has a resin layer 20 on a substrate 10 . Moreover, the resin layer 20 of FIG. 1 has a first resin layer 21 and a second resin layer 22 from the substrate 10 side.
Further, the first resin layer 21 of FIG. 1 has a region α1 independent of each other and a region α2 surrounding the region α1. Further, the second resin layer 22 of FIG. 1 has a region β1 independent of each other and a region β2 surrounding the region β1. In this specification, a structure having a region n1 independent of each other and a region n2 surrounding the region n1, like the first resin layer and the second resin layer in FIG. 1, is referred to as a "sea-island structure." sometimes referred to as
Note that FIG. 1 is a schematic cross-sectional view. That is, the reduced scale of each layer, the reduced scale of each material, and the reduced scale of the surface irregularities constituting the optical layered body 100 are schematic representations for ease of illustration, and are different from the actual reduced scale. Figures other than FIG. 1 are also different from the actual scale.

<Base material>
The substrate preferably has good light transmittance, smoothness, heat resistance and mechanical strength. Such substrates include polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, Resin substrates containing resins such as polyether ketone, acrylic resin, polycarbonate, polyurethane and amorphous olefin (Cyclo-Olefin-Polymer: COP) can be mentioned. The resin substrate may be a laminate of two or more resin substrates.
The resin substrate is preferably stretched in order to improve mechanical strength and dimensional stability.

Among the resin substrates, acrylic resin substrates are preferred because they have low hygroscopicity and therefore tend to have good dimensional stability, and have low optical anisotropy and thus tend to have good visibility. Further, the acrylic resin base material satisfies the condition 1 and or the condition 2 by setting the resin layer coating liquid to a predetermined composition and under predetermined drying conditions, and the first resin layer and the second resin layer The resin layer can easily have a sea-island structure.
Since the acrylic resin substrate is hard and brittle, it is difficult to achieve good adhesion when another layer is formed on the acrylic resin substrate. In particular, when a hard resin layer such as a resin layer containing a cured product of a curable resin composition is formed on an acrylic resin substrate, the adhesion between the substrate and the resin layer tends to be insufficient. The optical layered body of the present disclosure satisfies Condition 1 or Condition 2 even when a resin layer containing a cured product of a curable resin composition is formed on an acrylic resin substrate, and the resin layer has a sea-island structure. For example, it is possible to suppress a decrease in adhesion and to easily suppress a change in image definition.
As used herein, acrylic resin means acrylic resin and/or methacrylic resin.

The acrylic resin contained in the acrylic resin substrate is not particularly limited. ) those obtained using methyl acrylate are preferred. Further, as the acrylic resin, JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, JP-A-2005-146084, etc. things are also mentioned. As the acrylic resin, one having a ring structure such as an acrylic resin having a lactone ring structure or an acrylic resin having an imide ring structure may be used.

The acrylic resin preferably has a glass transition point (Tg) of 100° C. or higher and 150° C. or lower, more preferably 105° C. or higher and 135° C. or lower, even more preferably 110° C. or higher and 130° C. or lower.
When the acrylic resin has a glass transition point of 100° C. or higher, excessive dissolution of the acrylic resin base material can be easily suppressed during formation of the resin layer. When the glass transition point of the acrylic resin is 150° C. or lower, the degree of dissolution of the acrylic resin base material when forming the resin layer can be easily controlled.

The acrylic resin substrate may contain a resin other than the acrylic resin, but the ratio of the acrylic resin to the total resin constituting the acrylic resin substrate is preferably 80% by mass or more, and is 90% by mass or more. is more preferable, and 95% by mass or more is even more preferable.

The acrylic resin substrate can be produced, for example, by melt extruding pellets made of a humidity-conditioned acrylic resin, stretching the pellets in the longitudinal direction while cooling, and then stretching the pellets in the transverse direction.
In the melt-extrusion step, a screw having one screw, two screws, or two or more screws can be used, and the direction of rotation, number of rotations, and melting temperature of the screws can be set arbitrarily.
Stretching is preferably carried out so as to obtain a desired thickness after stretching. Moreover, although the draw ratio is not limited, it is preferably 1.2 times or more and 4.5 times or less. The temperature and humidity during stretching can be arbitrarily determined. The stretching method may be a general method.

The resin such as acrylic resin contained in the resin substrate preferably has a weight average molecular weight of 10,000 or more and 500,000 or less, more preferably 50,000 or more and 300,000 or less. By setting the weight-average molecular weight of the resin within the above range, conditions 1 and 2 and the sea-island structure can be easily controlled.

The average thickness of the substrate is preferably 10 µm or more, more preferably 20 µm or more, and even more preferably 35 µm or more. By setting the average thickness of the substrate to 10 μm or more, the optical layered body can be easily handled well.
The average thickness of the substrate is preferably 100 µm or less, more preferably 80 µm or less, and even more preferably 60 µm or less. By setting the average thickness of the base material to 100 μm or less, the flexibility resistance of the optical layered body can be easily improved.

The average thickness of the base material mentioned above means the average thickness of the base material when the optical laminate is completed. As will be described later, part of the base material is dissolved by the resin layer coating liquid, so that the average thickness of the base material when the optical layered body is completed may be smaller than the initial average thickness of the base material. . Therefore, it is preferable that the initial average thickness of the base material is greater than the average thickness of the base material when the optical layered body is completed. The difference between the initial average thickness of the base material and the average thickness of the base material when the optical layered body is completed varies depending on the thickness of the resin layer, the composition of the coating liquid for the resin layer, the drying conditions of the coating liquid, and the like. However, it is preferably 0.1 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less.

The average thickness of the substrate can be calculated, for example, by selecting 20 arbitrary points in a cross-sectional photograph of the optical layered body taken by a scanning transmission electron microscope (STEM) and calculating the average value thereof. It is preferable that the acceleration voltage of STEM is 10 kV or more and 30 kV or less, and the magnification of STEM is 1000 times or more and 7000 times or less.
Average thickness of the substrate, thickness of the first resin layer, thickness of the second resin layer, position of the region α1 in the thickness direction of the first resin layer, position of the first particles in the thickness direction of the resin layer, θa1 , θa2, Pa1, Pa2, etc., it is necessary to prepare a measurement sample in which the cross section of the optical layered body is exposed. The sample can be prepared, for example, by the following steps (A1) to (A2). If the interface is difficult to see due to insufficient contrast, the sample may be dyed with osmium tetroxide, ruthenium tetroxide, phosphotungstic acid, or the like as a pretreatment.

(A1) After preparing a cut sample by cutting the optical layered body into an arbitrary size, an embedding sample is prepared by embedding the cut sample in a resin. The size of the cut sample is, for example, a strip of 10 mm long×3 mm wide. The embedding resin is preferably an epoxy resin.
For the embedded sample, for example, the cut sample is placed in the silicon embedding plate, the embedding resin is poured in, and the embedding resin is cured. can be obtained by taking out the embedding resin that envelops the . In the case of the following epoxy resin manufactured by Struers, it is preferable that the above-described curing step is performed by allowing the resin to stand at room temperature for 12 hours. The shape of the embedded sample is block-like.
Examples of silicon embedding plates include those manufactured by Dosaka EM Co., Ltd. A silicon-embedded plate may also be referred to as a silicon capsule. As the epoxy resin for embedding, for example, a mixture of a trade name "Epofix" manufactured by Struers and a trade name "Hardener for Epofix" manufactured by the same company at a ratio of 10:1.2 can be used. .

(A2) A block-shaped embedded sample is cut vertically to prepare a sample for measurement in which the cross section of the optical layered body is exposed. As a sample for measurement, a thin section cut from the block-shaped embedded sample is used (the conditions for the sample for measurement will be described later). The embedded sample is preferably cut through the center of the cut sample. Embedded samples are preferably cut with a diamond knife.
An example of an apparatus for cutting an embedded sample is the product name "Ultramicrotome EM UC7" manufactured by Leica Microsystems. When cutting the embedded sample, it is preferable to first cut roughly (rough trimming) and finally trim precisely under the conditions of "SPEED: 1.00 mm/s" and "FEED: 70 nm".
Among the sections cut from the block-shaped embedded sample as described above, the section without defects such as holes and having a uniform thickness of 60 nm or more and 100 nm or less is the average thickness of the base material, the first resin layer thickness of the second resin layer, the position of the region α1 in the thickness direction of the first resin layer, the position of the first particles in the thickness direction of the resin layer, θa1, θa2, Pa1, Pa2, the first particles can be used as a sample for measuring the particle size of the inorganic fine particles.

In this specification, various measurements and evaluations, and the atmosphere in which sampling for measurement and evaluation is performed are measured at a temperature of 23 ± 5 ° C. and a relative humidity of 40% or more and 65% or less, unless otherwise specified. and In addition, the target optical layered body shall be exposed to the atmosphere for 30 minutes or longer before the measurement, evaluation and sampling.

The substrate may contain additives such as antioxidants, UV absorbers, light stabilizers and plasticizers.
The surface of the substrate may be subjected to physical treatment such as corona discharge treatment or chemical treatment, or may be formed with an easy-adhesion layer, in order to improve adhesion.

<Resin layer>
The resin layer is required to have a first resin layer and a second resin layer from the substrate side. By having the first resin layer and the second resin layer as the resin layers, it is possible to easily suppress a decrease in pencil hardness while improving adhesion.

When the resin layer is a single layer, it is difficult to improve the flex resistance or pencil hardness of the optical layered body. For example, in the case of a single resin layer having a high hardness, it is difficult to improve the bending resistance of the optical layered body. Further, in the case of a single resin layer having a low hardness, it is difficult to improve the pencil hardness of the optical layered body.

The first resin layer and the second resin layer are formed, for example, by coating a base material with a resin layer coating liquid containing a resin component and a solvent, drying it, and curing it as necessary. be able to. The resin layer coating liquid may further contain first particles, inorganic fine particles, and additives, if necessary.
In the case of the above method, for example, the resin layer coating liquid dissolves a part of the base material, and the resin component eluted from the base material is the main component, and the region containing a small amount of the resin component of the resin layer coating liquid is the first Furthermore, the content of the resin component eluted from the base material is small, and the second resin layer can be formed from the region containing the resin component as the main component of the coating liquid for the resin layer . That is, in the above method, the first resin layer and the second resin layer can be formed by one application using one resin layer coating liquid. Moreover, since the content of the resin component eluted from the substrate is small in the second resin layer formed by the above method, the pencil hardness can be easily improved.
In the above method, it is important to set the resin layer coating liquid to a predetermined composition and to set the drying conditions to predetermined conditions. The prescribed composition and prescribed drying conditions will be described later.
The method of applying the resin layer coating liquid onto the substrate is not particularly limited, and may be spin coating, dipping, spraying, die coating, bar coating, gravure coating, roll coating, meniscus coating, or flexographic printing. general-purpose coating methods such as coating method, screen printing method, and speed coater method.
When curing the resin layer coating liquid, it is preferable to irradiate ionizing radiation such as ultraviolet rays and electron beams. Specific examples of ultraviolet light sources include ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps and metal halide lamps. Moreover, the wavelength of the ultraviolet rays is preferably in the wavelength range of 190 nm or more and 380 nm or less. Specific examples of electron beam sources include various electron beam accelerators such as Cockcroftwald type, Vandegraft type, resonant transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type.

The first resin layer has a region α1 independent of each other and a region α2 surrounding the region α1, and the resin contained in the region α1 and the resin contained in the region α2 are required to be different. Furthermore, the second resin layer has a region β1 independent of each other and a region β2 surrounding the region β1, and the resin contained in the region β1 and the resin contained in the region β2 are required to be different. .
Since the first resin layer has the regions α1 and α2 and the second resin layer has the regions β1 and β2, the adhesion after the light resistance test can be easily improved.

The difference between the resin contained in the region α1 and the resin contained in the region α2 means that at least one of resin composition and molecular weight is different. It is preferable that the resin contained in the region α1 and the resin contained in the region α2 have different resin compositions. Examples of different resin compositions include the case where the region α1 and the region α2 contain different types of resin, and the case where the region α1 and the region α2 contain the same type of resin but differ in the mixing ratio of the resin.
The difference between the resin contained in the region β1 and the resin contained in the region β2 means that at least one of resin composition and molecular weight is different. It is preferable that the resin contained in the region β1 and the resin contained in the region β2 have different resin compositions. Examples of different resin compositions include the case where the regions β1 and β2 contain different types of resins, and the case where the regions β1 and β2 contain the same type of resins but differ in the mixing ratio of the resins.

In this specification, the resins of the region α1, region α2, region β1 and region β2 mean so-called binder resins. For this reason, particles such as first particles to be described later do not mean the resin of the region α1, the region α2, the region β1, and the region β2.

If the ratio of the region α1 is large, the hardness tends to be insufficient, and if the ratio of the region α2 is large, the adhesion tends to deteriorate. Therefore, the area ratio between the area α1 and the area α2 is preferably 1:99 to 10:90, more preferably 2:98 to 5:95.
If the proportion of the region β1 is large, the hardness tends to be insufficient, and if the proportion of the region β2 is large, the adhesion tends to deteriorate. Therefore, the area ratio between the region β1 and the region β2 is preferably 5:95 to 50:50, more preferably 10:90 to 40:60.
The above area ratio can be calculated from a cross-sectional photograph of the optical layered body taken by a scanning transmission electron microscope (STEM). In order to increase the reliability of the numerical values, a plurality of cross-sectional photographs are obtained, and the area ratio is calculated after setting the total number of the regions α1 or β1 to 50 or more.

In the first resin layer and the second resin layer, the resin contained in the region α1 and the resin contained in the region β2 are preferably substantially the same, and the resin contained in the region α2 and the resin contained in the region β1 It is preferable that the contained resin is substantially the same. By providing the above configuration, it is possible to easily improve the adhesion after the light resistance test. The reason why the adhesion after the light resistance test can be easily improved by the above configuration is that the affinity between the first resin layer and the second resin layer is increased, so that even in a harsh environment such as a light resistance test, the second It is considered that this is because the adhesiveness at the interface between the first resin layer and the second resin layer is less likely to deteriorate.

In order to make it easier to configure the first resin layer to have the region α1 and the region α2, and to make it easier to configure the second resin layer to have the region β1 and the region β2, It is preferable to reduce the compatibility between the components contained in the resin layer coating liquid, or to reduce the compatibility between the components contained in the resin layer coating liquid and the components eluted from the substrate.
By lowering the compatibility as described above, it is believed that the structures of the first resin layer and the second resin layer of the present disclosure can be easily formed due to the events (1) to (4) below.
(1) Part of the substrate dissolves when the resin layer coating liquid is applied onto the substrate.
(2) The resin component eluted from the base material is the main component, and the region containing a small amount of the resin component of the resin layer coating liquid serves as the first resin layer, and the content of the resin component eluted from the base material is small, A region containing the resin component of the resin layer coating liquid as a main component becomes the second resin layer.
(3) Due to the low compatibility, in the above (2), the resin component of the resin layer coating liquid contained in a small amount in the first resin layer forms the region α1, and the resin component eluted from the base material forms the region α1. Form α2.
(4) Due to the low compatibility, in the above (2), the resin component eluted from the base material contained in a small amount in the second resin layer forms the region β1, and the resin component of the resin layer coating liquid forms the region β1. β2 is formed.

When defining the base material side from the center of the thickness direction of the first resin layer as the first region and the second resin layer side from the center of the thickness direction of the first resin layer as the second region, 70 of the region α1 % or more is present in the second region. By having the said structure, the adhesiveness after a light resistance test can be made more favorable easily.

The proportion of the regions α1 existing in the second regions is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more based on the number.

In this specification, the position where the region α1 exists in the thickness direction of the first resin layer is determined by the following methods (1) to (5).
(1) A cross-sectional photograph of the optical layered body is taken with a scanning transmission electron microscope (STEM). It is preferable that the acceleration voltage of STEM is 10 kV or more and 30 kV or less, and the magnification of STEM is 1000 times or more and 7000 times or less.
(2) Based on the cross-sectional photograph, calculate the average altitude X1 of the ridgelines on the surface of the first resin layer on the base material side and the average altitude X2 of the ridgelines on the surface of the first resin layer on the second resin layer side. (see symbols X1 and X2 in FIG. 2).
(3) The center M in the thickness direction of the first resin layer is defined as the middle point between X1 and X2 (see symbol M in FIG. 2).
(4) Based on the cross-sectional photograph, the region α1 existing in the first region on the substrate side from the center of the first resin layer in the thickness direction, and the second resin layer from the center of the thickness direction of the first resin layer count the number of regions α1 existing in the second region on the side. The number of regions α1 existing in both the first region and the second region across the center in the thickness direction of the first resin layer is in the first region and the second region according to the area ratio of the region α1 Allocate For example, for a region α1 with an area ratio of 40% in the first region and 60% in the second region, 0.4 is allocated to the first region and 0.6 to the second region. Allocate.
(5) In order to increase the reliability of the numerical value, obtain a plurality of cross-sectional photographs, set the total number of the regions α1 to 50 or more, and the number-based ratio of the regions α1 existing in the first region and the second region Calculate

The lower limit of the thickness of the entire resin layer (in other words, the total thickness of the first resin layer and the second resin layer) is preferably 4.0 μm or more, more preferably 5.0 μm or more, and more preferably 6.0 μm or more. More preferably, the upper limit is preferably 15.0 μm or less, more preferably 12.0 μm or less, and even more preferably 10.0 μm or less.
The average thickness t1 of the first resin layer has a lower limit of preferably 3.0 µm or more, more preferably 4.0 µm or more, and still more preferably 4.5 µm or more, and an upper limit of 10.0 µm or less, preferably 8.0 µm. The following is more preferable, and 7.0 μm or less is even more preferable. By setting t1 to 3.0 μm or more, adhesion and bending resistance can be easily improved, and by setting t1 to 10.0 μm or less, it is possible to easily suppress a decrease in pencil hardness.
The average thickness t2 of the second resin layer has a lower limit of preferably 0.3 μm or more, more preferably 0.5 μm or more, and still more preferably 1.0 μm or more, and an upper limit of 4.0 μm or less, preferably 3.0 μm. The following is more preferable, and 2.7 μm or less is even more preferable. By setting t2 to 0.3 μm or more, the pencil hardness can be easily improved, and by setting t2 to 4.0 μm or less, deterioration of bending resistance can be easily suppressed.

t1/t2 is preferably 1.5 or more, more preferably 1.8 or more, and further preferably 2.0 or more, in order to easily suppress deterioration in adhesion and bending resistance. preferable. Also, t1/t2 is preferably 10.0 or less, more preferably 5.0 or less, and even more preferably 3.0 or less, in order to easily improve the pencil hardness.

The average thickness of the first resin layer and the average thickness of the second resin layer are determined, for example, by selecting 20 arbitrary points in a cross-sectional photograph of the optical layered body taken by a scanning transmission electron microscope (STEM). It can be calculated from the average value. It is preferable that the acceleration voltage of STEM is 10 kV or more and 30 kV or less, and the magnification of STEM is 1000 times or more and 7000 times or less.

《Resin component》
The resin layer preferably contains a cured product of a curable resin composition as a resin component. By including the cured product of the curable resin composition in the resin layer, it is possible to easily improve the pencil hardness of the optical layered body.

The ratio of the curable resin composition to the total amount of the resin component in the resin layer coating liquid is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. Preferably, 100% by mass is most preferable.

The cured product of the curable resin composition includes a cured product of a thermosetting resin composition and a cured product of an ionizing radiation-curable resin composition. Among these, a cured product of an ionizing radiation-curable resin composition is preferable because it is easy to increase the pencil hardness and to easily dissolve the substrate in the uncured state of the composition.

A thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating.
Thermosetting resins include acrylic resins, urethane resins, phenol resins, urea melamine resins, epoxy resins, unsaturated polyester resins, silicone resins, and the like. If necessary, a curing agent is added to these curable resins in the thermosetting resin composition.

The ionizing radiation-curable resin composition is a composition containing a compound having an ionizing radiation-curable functional group (hereinafter also referred to as an "ionizing radiation-curable compound"). Examples of ionizing radiation-curable functional groups include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, epoxy groups, and oxetanyl groups. As the ionizing radiation-curable compound, a compound having an ethylenically unsaturated bond group is preferred.
Ionizing radiation refers to electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or cross-linking molecules. Usually, ultraviolet rays or electron beams are used, but other electromagnetic waves such as X-rays and gamma rays are also used. , α-rays, ion beams, and other charged particle beams can also be used.
As used herein, a (meth)acryloyl group refers to an acryloyl group or a methacryloyl group. Moreover, in this specification, (meth)acrylate indicates acrylate or methacrylate.

As the ionizing radiation-curable compound, both a monofunctional ionizing radiation-curable compound having one ionizing radiation-curable functional group and a polyfunctional ionizing radiation-curable compound having two or more ionizing radiation-curable functional groups are used. be able to. Both monomers and oligomers can be used as the ionizing radiation-curable compound. Since the monofunctional ionizing radiation-curable monomer tends to have good compatibility with other resin components, it tends to be difficult to form a sea-island structure in the first resin layer and the second resin layer. When using monofunctional ionizing radiation-curable monomers, the aforementioned properties should be noted.
In order to partially dissolve the base material, form a sea-island structure in the first resin layer and the second resin layer, increase the pencil hardness, and facilitate suppression of cure shrinkage, It is preferable to use the following mixtures (a) to (c) as the ionizing radiation-curable compound. The following (a) to (c) are preferably compounds having an ethylenically unsaturated bond group as an ionizing radiation-curable functional group, more preferably (meth)acrylate compounds. As the (meth)acrylate compound, a part of the molecular skeleton modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol or the like can also be used.
(a) difunctional ionizing radiation-curable monomer (b) trifunctional or higher ionizing radiation-curable monomer (c) polyfunctional ionizing radiation-curable oligomer

By including the bifunctional ionizing radiation-curable monomer (a) as the ionizing radiation-curable compound, a part of the base material can be easily dissolved, so that θa1 or Pa1 can be easily increased. However, if the amount of the bifunctional ionizing radiation-curable monomer (a) is too large, the substrate may be excessively dissolved, resulting in a decrease in strength of the substrate or a decrease in pencil hardness of the optical laminate. There is
By containing the trifunctional or higher ionizing radiation-curable monomer (b) as the ionizing radiation-curable compound, the pencil hardness of the optical layered body can be easily improved. However, if the amount of the tri- or higher functional ionizing radiation-curable monomer (b) is too large, the hardness of the resin layer may become too high and the flex resistance of the optical layered body may decrease.
By containing the polyfunctional ionizing radiation-curable oligomer (c) as the ionizing radiation-curable compound, curing shrinkage can be easily suppressed while maintaining the pencil hardness of the optical laminate. However, if the amount of the polyfunctional ionizing radiation-curable oligomer (c) is too large, the pencil hardness of the optical laminate may decrease.

The amount of the bifunctional ionizing radiation-curable monomer (a) with respect to the total amount of the ionizing radiation-curable compound is preferably 10% by mass or more and 40% by mass or less, and is 13% by mass or more and 30% by mass or less. is more preferable, and more preferably 15% by mass or more and 25% by mass or less.
The amount of the trifunctional or higher ionizing radiation-curable monomer (b) with respect to the total amount of the ionizing radiation-curable compound is preferably 25% by mass or more and 55% by mass or less, and is 30% by mass or more and 50% by mass or less. is more preferable, and more preferably 35% by mass or more and 45% by mass or less.
The amount of (c) polyfunctional ionizing radiation-curable oligomer relative to the total amount of ionizing radiation-curable compounds is preferably 25% by mass or more and 55% by mass or less, and is preferably 30% by mass or more and 50% by mass or less. More preferably, it is 35% by mass or more and 45% by mass or less.

The bifunctional ionizing radiation-curable monomer (a) includes ethylene glycol di(meth)acrylate, bisphenol A tetraethoxy diacrylate, bisphenol A tetrapropoxy diacrylate, 1,6-hexanediol diacrylate and the like.

Trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, as (b) ionizing radiation-curable monomers having trifunctional or higher functionality, dipentaerythritol tetra(meth)acrylate, isocyanuric acid-modified tri(meth)acrylate, and the like.
The number of functional groups of the tri- or higher ionizing radiation-curable monomer (b) is preferably 3 or more and 5 or less, more preferably 3 or more and 4 or less, in order to suppress curing shrinkage while increasing pencil hardness. Preferably, 3 is more preferable.

Examples of the polyfunctional ionizing radiation-curable oligomer (c) include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate.
Urethane (meth)acrylates are obtained, for example, by reacting polyhydric alcohols and organic diisocyanates with hydroxy (meth)acrylates.
Preferred epoxy (meth)acrylates include (meth)acrylates obtained by reacting tri- or more functional aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc. with (meth)acrylic acid; (Meth)acrylates obtained by reacting aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc. with polybasic acids and (meth)acrylic acid, and bifunctional or higher aromatic epoxy resins, alicyclic It is a (meth)acrylate obtained by reacting a group epoxy resin, an aliphatic epoxy resin, or the like with a phenol and (meth)acrylic acid.

The number of functional groups in the polyfunctional ionizing radiation-curable oligomer (c) is preferably 4 or more and 8 or less, more preferably 5 or more and 7 or less, in order to suppress cure shrinkage while maintaining pencil hardness. , 6.
The weight-average molecular weight of the polyfunctional ionizing radiation-curable oligomer (c) is preferably 1000 to 5000, more preferably 1100 to 3500, in order to maintain pencil hardness while suppressing curing shrinkage. More preferably 1200-2000.
As used herein, the weight average molecular weight is the average molecular weight measured by GPC analysis and converted to standard polystyrene.

When the ionizing radiation-curable compound is an ultraviolet-curable compound, the ionizing radiation-curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyldimethylketal, benzoylbenzoate, α-acyloxime ester, thioxanthones, and the like.
The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing speed, and is selected from, for example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, and the like. One or more types are mentioned.

《First particle》
The resin layer preferably contains first particles having an average particle size of 0.5 μm or more in order to easily improve the antiglare property. In order to facilitate better antiglare properties, it is more preferable that the second resin layer contains the first particles.

It is preferable that 70% or more of the first particles based on the number of the first particles exist on the second resin layer side in order to easily improve the antiglare property. The ratio is preferably 80% or more, more preferably 90% or more.

The position of the first particles in the thickness direction of the resin layer can be determined, for example, from a cross-sectional photograph of the optical layered body taken with a scanning transmission electron microscope (STEM). Moreover, the ratio based on the number mentioned above can be calculated from the cross-sectional photograph. In order to increase the reliability of the numerical value, it is preferable to obtain a plurality of cross-sectional photographs, set the total number of the first particles to 50 or more, and then calculate the ratio based on the above number.
In addition, the first particles present in both the first resin layer and the second resin layer across the first resin layer and the second resin layer are divided according to the area ratio of each layer. Allocate the number to For example, 0.4 of the first particles present in the first resin layer with an area ratio of 40% and in the second resin layer with an area ratio of 60% are allocated to the first resin layer. , and assign 0.6 to the second resin layer.
It is preferable that the acceleration voltage of STEM is 10 kV or more and 30 kV or less, and the magnification of STEM is 1000 times or more and 7000 times or less.

As the first particles, resins such as polymethyl methacrylate, polyacrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone, fluorine-based resin and polyester-based resin. inorganic particles formed from one or more inorganic substances such as silica, alumina, zirconia and titania; Among these, organic particles are preferable because they are excellent in dispersion stability and have a relatively small specific gravity, so that the first particles can be easily positioned in the second resin layer.

The lower limit of the content of the first particles is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, with respect to 100 parts by mass of the resin component of the resin layer coating liquid. It is preferably 1.3 parts by mass or more, and the upper limit is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, and 3.0 parts by mass or less. It is even more preferable to have
By setting the content of the first particles to 0.5 parts by mass or more, the antiglare property can be easily improved. Further, by setting the content of the first particles to 10.0 parts by mass or less, it is possible to easily suppress deterioration in bending resistance.

The average particle size of the first particles is preferably 0.8 μm or more, and more preferably 1.0 μm or more, in order to facilitate good antiglare properties.
The average particle size of the first particles is preferably 3.0 μm or less, more preferably 2.7 μm or less, and 2.5 μm or less in order to easily suppress deterioration in bending resistance. is more preferred.

The average particle size of the first particles can be calculated, for example, by the following operations (B1) to (B3).
(B1) Take a transmission observation image of the optical layered body with an optical microscope. The magnification is preferably 500 times or more and 2000 times or less.
(B2) Extract arbitrary 10 particles from the observation image and calculate the particle diameter of each particle. The particle diameter is measured as the distance between two straight lines that provide the maximum distance between two parallel straight lines that sandwich the cross section of the particle.
(B3) Perform the same operation 5 times on different screen observation images of the same sample, and take the value obtained from the number average of the particle diameters for a total of 50 particles as the average particle diameter of the particles.
However, when the first particles cannot be optically observed, the average particle diameter of the first particles is calculated by the following (B4) to (B6).
(B4) From the optical layered body, a section that passes through the center of the first particle is produced by a microtome. The thickness of the section is preferably 60 nm to 100 nm. A plurality of sections are continuously produced for each first particle, and the section that maximizes the particle diameter calculated from each section by the operation of (B5) is taken as the section that passes through the center of the first particle. be able to.
(B5) The obtained section is observed with a scanning transmission electron microscope (STEM) to calculate the particle size. The method for calculating the particle size is the same as in (B2). The magnification is preferably 5,000 times or more and 20,000 times or less.
(B6) The operations of (B4) to (B5) are performed on 20 particles, and the value obtained from the number average of the particle diameters of 20 particles is taken as the average particle diameter of the first particles.

Regarding D1 indicating the average particle diameter of the first particles and t2 indicating the average thickness of the second resin layer, t2-D1 is preferably −0.5 μm or more and 2.0 μm or less. is preferred.
When t2−D1 is −0.5 μm or more, the first particles can easily provide the surface of the optical layered body with an uneven shape, so that the antiglare property can be easily improved. t2-D1 is more preferably 0 μm or more, further preferably 0.1 μm or more.
When t2−D1 is 2.0 μm or less, the first particles are less likely to protrude from the surface of the second resin layer, thereby making it easier to improve the scratch resistance. t2-D1 is more preferably 1.5 μm or less, and even more preferably 0.8 μm or less.

《Inorganic fine particles》
The resin layer may contain inorganic fine particles. Since the resin layer contains inorganic fine particles having a relatively large specific gravity, the first particles are less likely to sink below the resin layer, and the first particles can be easily positioned in the second resin layer. In addition, the inorganic fine particles can enhance the dispersibility of the first particles and easily suppress the deterioration of the bending resistance.
In this specification, inorganic fine particles mean inorganic particles having an average primary particle size of 200 nm or less.
The average particle diameter of the inorganic fine particles is preferably 1 nm or more and 200 nm or less, more preferably 2 nm or more and 100 nm or less, and even more preferably 5 nm or more and 50 nm or less.

The average particle size of the inorganic fine particles can be calculated by the following operations (C1) to (C3).
(C1) Take an image of the cross section of the optical laminate with a TEM or STEM. The acceleration voltage of the TEM or STEM is preferably 10 kV or more and 30 kV or less, and the magnification is preferably 50,000 times or more and 300,000 times or less.
(C2) Any 10 inorganic fine particles are extracted from the observation image, and the particle diameter of each inorganic fine particle is calculated. The particle diameter is measured as the distance between two arbitrary parallel straight lines sandwiching the cross section of the inorganic fine particles, and the distance between the two straight lines being the maximum.
(C3) Perform the same operation 5 times on observation images of the same sample on different screens, and use the average particle diameter of the inorganic fine particles as the value obtained from the number average of the particle diameters for a total of 50 particles.

Examples of inorganic fine particles include fine particles made of silica, alumina, zirconia, titania, and the like. Among these, silica is preferable since it easily suppresses the generation of internal haze.

The lower limit of the content of the inorganic fine particles is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, with respect to 100 parts by mass of the resin component of the resin layer coating liquid. It is more preferably 0.7 parts by mass or more, and the upper limit is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and 2.0 parts by mass or less. is more preferred.
By setting the content of the inorganic fine particles to 0.1 part by mass or more, the first particles can be easily positioned in the second resin layer. Further, by setting the content of the inorganic fine particles to 5.0 parts by mass or less, it is possible to prevent the first particles from excessively floating above the resin layer, and thus it is possible to easily prevent deterioration of the bending resistance.

"Additive"
The resin layer coating liquid may contain leveling agents, refractive index modifiers, antistatic agents, antifouling agents, UV absorbers, light stabilizers, antioxidants, viscosity modifiers, thermal polymerization initiators, etc., as necessary. It may contain additives.

"solvent"
The resin layer coating liquid preferably contains a solvent.
As the solvent, it is preferable to select a solvent that can dissolve the substrate. The values of θa1 and Pa1 tend to increase as the solvent that dissolves the base material is used more easily. However, if the base material is dissolved excessively, the strength of the base material is lowered, so it is preferable to select an appropriate solvent according to the type of base material.
In addition, it is preferable to select the solvent in consideration of not only the solubility of the base material but also the evaporation rate inherent to the solvent. The rate at which the solvent evaporates can also be controlled by the drying conditions. For example, the higher the drying temperature, the faster the solvent will evaporate. Also, the faster the drying air speed, the faster the solvent evaporates.
If the drying of the solvent is slow, the dissolution of the substrate proceeds, and θa1 and Pa1 tend to increase. Further, if the drying of the solvent is slow and the drying temperature is high, the resin component moves rapidly between the first resin layer and the second resin layer, and θa2 and Pa2 tend to increase.
From the above, it is preferable to select the solvent in consideration of the solubility of the substrate, the evaporation rate, and the drying conditions.

Examples of solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers such as dioxane and tetrahydrofuran; aliphatic hydrocarbons such as hexane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons; halogenated carbons such as dichloromethane and dichloroethane; esters such as methyl acetate, ethyl acetate and butyl acetate; alcohols such as isopropanol, butanol and cyclohexanol; cellosolves such as methyl cellosolve and ethyl cellosolve; glycol ethers such as propylene glycol monomethyl ether acetate; cellosolve acetates; sulfoxides such as dimethylsulfoxide; amides such as dimethylformamide and dimethylacetamide; The solvent may be used singly or as a mixture of two or more.

An acrylic resin base material is easily dissolved in a solvent. Therefore, when an acrylic resin base material is used as the base material, it is preferable that the solvent contains a solvent having a high evaporation rate.
In the present specification, a solvent with a high evaporation rate means a solvent with an evaporation rate of 100 or more when the evaporation rate of butyl acetate is set to 100. Further, in this specification, a solvent with a slow evaporation rate means a solvent with an evaporation rate of less than 100 when the evaporation rate of butyl acetate is 100.

The evaporation rate of the solvent having a high evaporation rate is more preferably 120 or more and 450 or less, and even more preferably 140 or more and 400 or less.
Solvents with high evaporation rates include, for example, isopropyl alcohol (evaporation rate of 150), methyl isobutyl ketone (evaporation rate of 160), toluene (evaporation rate of 200), and methyl ethyl ketone (evaporation rate of 370).
The solvent having a fast evaporation rate is preferably 75% by mass or more and 85% by mass or less of the total amount of the solvent.

In order to facilitate the formation of the sea-island structure in the first resin layer and the second resin layer, the solvent should contain a solvent that has a slow evaporation rate, high polarity, and a large molecular weight. is preferred. A solvent having the properties described above increases the viscosity of the coating liquid, so that the coating liquid tends to gel. Therefore, the solvent having the properties described above can easily reduce the compatibility of the coating liquid, so that the sea-island structure can be easily formed. Solvents with the properties described above include cyclohexanone and diacetone alcohol.
The solvent that evaporates slowly, has high polarity, and has a large molecular weight preferably accounts for 15% by mass or more and 25% by mass or less of the total amount of the solvent.

《Drying conditions》
When forming the resin layer from the resin layer coating liquid, it is preferable to control the drying conditions.
Further, in the optical layered body of the present disclosure, it is preferable to dry the resin layer coating liquid in two stages. Specifically, it is preferable to reduce the drying air velocity in the first stage of drying and increase the drying air velocity in the second stage of drying. At the time of drying in the first stage, a first resin layer is formed by a region containing a resin component eluted from the base material as a main component and containing a small amount of the resin component of the resin layer coating liquid, and the resin eluted from the base material. A second resin layer can be formed by a region containing a small amount of the component and containing the resin component of the resin layer coating liquid as a main component. Furthermore, by increasing the drying temperature in the first step, the resin component can be easily moved, thereby facilitating the formation of the islands-in-the-sea structure.
By performing the second stage of drying, excessive dissolution of the base material can be suppressed, so that θa1 and Pa1 can be easily suppressed from becoming too large.

Furthermore, it is preferable to control the drying time in the first-stage drying and the second-stage drying. A longer drying time for drying the coating liquid for the resin layer means that it takes longer to irradiate the resin component of the coating liquid for the resin layer with the ionizing radiation. In other words, lengthening the drying time of the resin layer coating liquid means that the resin component of the resin layer coating liquid maintains an uncured and fluid state for a long time. Therefore, if the drying time for drying the coating solution for the resin layer becomes long, the resin component moves rapidly between the first resin layer and the second resin layer, and θa2 and Pa2 tend to increase. , conditions 1 and 2 are less likely to be satisfied.

Drying conditions can be controlled by drying temperature and air speed in the dryer. The preferred ranges for the drying temperature and air velocity vary depending on the composition of the resin layer coating liquid, so it cannot be generalized, but the following conditions are preferred.
<Drying in the first stage>
The drying temperature is preferably 75° C. or higher and 95° C. or lower, and the drying wind speed is preferably 1 m/s or higher and 10 m/s or lower. The drying time is preferably 20 seconds or more and 40 seconds or less.
<Drying in the second step>
The drying temperature is preferably 75° C. or higher and 95° C. or lower, and the drying wind speed is preferably 15 m/s or higher and 30 m/s or lower. The drying time is preferably 20 seconds or more and 40 seconds or less.

Ionizing radiation is applied after drying the coating liquid in order to dissolve a part of the base material with the coating liquid for the resin layer and to facilitate sufficient mixing of the components eluted from the base material and the coating liquid for the resin layer. is preferred.

<Other layers>
The optical laminate may have layers other than the substrate and the resin layer. Other layers include an antireflection layer, an antifouling layer, an antistatic layer, and the like.

<Condition 1, Condition 2>
The optical laminate of the present disclosure needs to satisfy Condition 1 or Condition 2 below. Although the optical layered body of the present disclosure should satisfy at least one of Condition 1 and Condition 2, it preferably satisfies both.
<Condition 1>
θa1 indicating the average inclination angle of the surface of the base material facing the resin layer and θa2 indicating the average inclination angle of the surface of the first resin layer facing the second resin layer have a relationship of θa2<θa1. is.
<Condition 2>
Pa1 indicating the arithmetic mean height of the surface of the base material on the resin layer side and Pa2 indicating the arithmetic mean height of the surface of the first resin layer on the second resin layer side satisfy Pa2<Pa1 is the relationship.

-Condition 1-
If the relationship θa2<θa1 is not satisfied, the small θa1 makes it difficult to achieve good initial adhesion, and the large θa2 makes it difficult to suppress the change in transmission image definition after the lightfastness test.
The reason why the transmission image definition changes before and after the light resistance test is considered to be that the refractive index difference at the interface between the first resin layer and the second resin layer changes between before and after the light resistance test. In the optical laminate of the present disclosure, there is not only the interface between the first resin layer and the second resin layer, but also the interface between the substrate and the first resin layer. Substrates (especially acrylic resin substrates) are relatively resistant to denaturation in lightfastness tests. On the other hand, the resin component of the resin layer coating liquid is relatively easily denatured by the light resistance test. For this reason, the refractive index of the second resin layer, which contains a small amount of the resin component of the substrate, tends to change before and after the light resistance test. On the other hand, the substrate and the first resin layer containing a large amount of the resin component of the substrate are less likely to change in refractive index before and after the light resistance test. Therefore, if the relationship θa2<θa1 is not satisfied due to the large θa2, it is considered difficult to suppress the change in the clarity of the transmitted image after the lightfastness test.

-Condition 2-
If the relationship Pa2<Pa1 is not satisfied, a small Pa1 makes it difficult to achieve good initial adhesion, and a large Pa2 makes it difficult to suppress changes in transmission image definition after the lightfastness test.
The reason why it is difficult to suppress the change in transmission image definition after the lightfastness test when Pa2<Pa1 is not satisfied due to the large Pa2 is considered to be the same as the reason for the condition 1.

θa1 is preferably 5.0 degrees or more, more preferably 8.0 degrees or more, and still more preferably 10.0 degrees or more, in order to facilitate good initial adhesion. θa1 is preferably 20.0 degrees or less, more preferably 18.0 degrees or less, and even more preferably 17.0 degrees or less, in order to easily improve the pencil hardness.

θa2 is preferably 10.0 degrees or less, more preferably 8.0 degrees or less, still more preferably 6.0 degrees or less, in order to easily suppress changes in transmission image definition after the light resistance test, and 4.0 degrees. degree or less is even more preferable.
θa2 is preferably greater than 0 degrees, more preferably 1.0 degrees or more, and even more preferably 2.0 degrees or more, in order to facilitate good adhesion.

Pa1 is preferably 0.05 μm or more, more preferably 0.07 μm or more, and even more preferably 0.10 μm or more, in order to facilitate good initial adhesion. Pa1 is preferably 0.25 μm or less, more preferably 0.23 μm or less, and even more preferably 0.20 μm or less, in order to easily improve the pencil hardness.

Pa2 is preferably 0.15 μm or less, more preferably 0.13 μm or less, still more preferably 0.10 μm or less, and more preferably 0.06 μm or less, in order to easily suppress a change in transmission image definition after the light resistance test. More preferred.
Pa2 is preferably 0.02 μm or more, more preferably 0.04 μm or more, and still more preferably 0.05 μm or more, in order to facilitate good adhesion.

θa1 and θa2, and Pa1 and Pa2 can be measured, for example, as follows.
(1) A cross-sectional photograph of the optical laminate is taken with a scanning transmission electron microscope (STEM). It is preferable that the acceleration voltage of STEM is 10 kV or more and 30 kV or less, and the magnification of STEM is 5000 times or more and 10000 times or less.
(2) From the image of the cross-sectional photograph, the ridgeline of the interface between the base material and the resin layer and the ridgeline of the interface between the first resin layer and the second resin layer are obtained, and height data is obtained. Concretely, it is done as follows. The interface between the substrate and the resin layer corresponds to the surface of the substrate on the resin layer side. The interface between the first resin layer and the second resin layer corresponds to the surface of the first resin layer on the second resin layer side.
(a) Display captured images with the open source and public domain image processing software ImageJ (version 1.52a).
(b) Obtain the length per pixel from the scale representation displayed in the image.
(c) Select “FreeHand Selections”, create a ROI that includes the interface, and adjust the Brightness so that the colors are clearly different across the interface.
(d) Apply Process-Smooth twice.
(e) Set Image-Type to 8bit.
(f) Select “Straight” to draw a line along the interface.
(g) Install and run ABSnake, which is a Plugin of ImageJ. At that time, set “Gradient threshold” to 10 and set Draw color to Red. Leave other settings as default.
(h) Visually confirm that the interface is traced with Red. If it is defective, start over from (f).
(i) Run Image-Adjust-Color Threshold. Set a threshold to separate Red from the rest. Specifically, set the color space to RGB, check "Pass" for "Red", "Green" and "Blue", set the upper and lower limits of the Red range to the maximum value (255), and set "Green" and " Set the upper and lower limits of the range of "Blue" to the minimum value (0).
(j) Execute Process-Binary-Make Binary to binarize the trace line portion of the interface and the portion other than the trace line.
(k) Save the binarized data with “Text Image” with File-Save As.
(l) From the binarized data, convert the interface into a height data point sequence.
(3) Calculate the average tilt angle and the arithmetic average height from the height data point sequence according to the following procedure.
(m) Obtain the center line of the height data by quadratic regression using the least squares method, and subtract the center line from the height data so that the center line is 0 and the upward direction is positive, and the downward direction is negative. Let the direction of the center line be the x-axis, and the direction perpendicular to it (height direction) be the y-axis.
(n) Convert the height data to length using the length per pixel obtained in (b).
(o) Apply a Gaussian low-pass filter with a cut-off wavelength of 0.5 μm.
(p) tan ⁻¹ ((y _i+1 −y _i−1 )/2Δx) [y _i is the height at the i-th point in the height data point sequence, Δx is the x-axis distance between adjacent points] θa1 and θa2 are obtained by calculating the arithmetic mean of the absolute values of the tilt angles of the obtained points.
(q) Arithmetic mean heights Pa1 and Pa2 are calculated by calculating the arithmetic mean of the absolute values of the heights at each point.

In this specification, θa1 and θa2, and Pa1 and Pa2 mean average values of measured values of 20 samples.
In order to set θa1 and θa2 and Pa1 and Pa2 within the above ranges, as described above, a part of the base material should be dissolved in the resin layer coating liquid, and the composition of the resin layer coating liquid should be appropriately prepared. It is important to set the drying conditions of the resin layer coating liquid within an appropriate range.

<Optical properties, surface shape>
The optical laminate preferably has a total light transmittance of 70% or more, more preferably 80% or more, and even more preferably 85% or more according to JIS K7361-1:1997.
The light incident surface for measuring the total light transmittance and haze, which will be described later, is the substrate side.

The optical laminate preferably has a JIS K7136:2000 haze of 0.5% or more, more preferably 1.0% or more, and even more preferably 1.5% or more. By setting the haze to 0.5% or more, the antiglare property can be easily improved.
Further, in order to easily suppress deterioration in image resolution, the optical laminate preferably has a haze of 20% or less, more preferably 10% or less, and even more preferably 5% or less.

In order to facilitate good antiglare properties, the optical layered body preferably has an arithmetic mean roughness Ra of JIS B0601:2001 on the resin layer side surface of 0.03 μm or more, more preferably 0.05 μm or more. is more preferred. Moreover, in order to easily suppress deterioration in image resolution, the optical layered body preferably has an Ra of the surface on the resin layer side of 0.12 μm or less, more preferably 0.10 μm or less. Ra means a value at a cutoff value of 0.8 mm.

<Size, shape, etc.>
The optical layered body may be in the form of a sheet cut into a predetermined size, or may be in the form of a roll obtained by winding a long sheet. The size of the sheet is not particularly limited, but the maximum diameter is about 2 inches or more and 500 inches or less. The “maximum diameter” refers to the maximum length of the optical layered body when any two points are connected. For example, when the optical layered body is rectangular, the diagonal of the rectangle is the maximum diameter. When the optical layered body is circular, the diameter of the circle is the maximum diameter.
The width and length of the roll are not particularly limited, but generally the width is about 500 mm or more and 3000 mm or less, and the length is about 500 m or more and 5000 m or less. The roll-shaped optical layered body can be used by being cut into sheets according to the size of an image display device or the like. When cutting, it is preferable to exclude the roll ends whose physical properties are not stable.
The shape of the sheet is not particularly limited, and may be, for example, a polygon such as a triangle, quadrangle, or pentagon, a circle, or a random irregular shape. More specifically, when the optical layered body has a rectangular shape, the aspect ratio is not particularly limited as long as there is no problem as a display screen. For example, horizontal:vertical=1:1, 4:3, 16:10, 16:9, 2:1, 5:4, 11:8.

[Polarizer]
A polarizing plate of the present disclosure has a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer. A polarizing plate, wherein at least one of the first transparent protective plate and the second transparent protective plate is the above-described optical layered body of the present disclosure.

A polarizing plate is used, for example, to impart antireflection properties by combining a polarizing plate and a λ/4 retardation plate. In this case, the λ/4 retardation plate is arranged on the display element of the image display device, and the polarizing plate is arranged on the viewer side of the λ/4 retardation plate.
When a polarizing plate is used for a liquid crystal display device, the polarizing plate is used to provide the function of a liquid crystal shutter. In this case, the liquid crystal display device is arranged in the order of the lower polarizing plate, the liquid crystal display element, and the upper polarizing plate, and the absorption axis of the polarizer of the lower polarizing plate and the absorption axis of the polarizer of the upper polarizing plate are perpendicular to each other. placed. In the above configuration, the polarizing plate of the present disclosure is preferably used as the upper polarizing plate.

<Transparent protective plate>
The polarizing plate of the present disclosure is the optical layered body of the present disclosure in which at least one of the first transparent protective plate and the second transparent protective plate is described above. A preferred embodiment is an embodiment in which, of the first transparent protective plate and the second transparent protective plate, the transparent protective plate on the light emitting side is the above-described optical layered body of the present disclosure. The optical layered body is preferably arranged so that the substrate-side surface of the optical layered body faces the polarizer.

When one of the first transparent protective plate and the second transparent protective plate is the above-described optical laminate of the present disclosure, the other transparent protective plate is not particularly limited, but an optically isotropic transparent protective plate is preferable. .
As used herein, optically isotropic refers to an in-plane retardation of 20 nm or less, preferably 10 nm or less, more preferably 5 nm or less. Acrylic films and triacetyl cellulose (TAC) films are easy to impart optical isotropy.

<Polarizer>
As a polarizer, for example, sheet-type polarizers such as polyvinyl alcohol film, polyvinyl formal film, polyvinyl acetal film, ethylene-vinyl acetate copolymer system saponified film dyed with iodine or the like and stretched; wire grid type polarizers made of metal wires, coating type polarizers coated with lyotropic liquid crystals or dichroic guest-host materials, multilayer thin film type polarizers, and the like. These polarizers may be reflective polarizers having the function of reflecting non-transmissive polarized light components.

<Size, shape, etc.>
Embodiments of the size and shape of the polarizing plate of the present disclosure include the above-described embodiments of the size and shape of the optical layered body of the present disclosure.

[Image display device]
The image display device of the present disclosure has the above-described optical layered body of the present disclosure on a display element.

FIG. 3 is a cross-sectional view showing an embodiment of an image display device 500 of the present disclosure. The image display device 500 of FIG. 3 has the optical laminate 100 of the present disclosure on the display element 200 . In the image display device, the optical layered body is preferably arranged so that the substrate side faces the display element side.

Display elements include liquid crystal display elements; EL display elements (organic EL display elements, inorganic EL display elements); plasma display elements; display elements using QD (Quantum dot); LED displays such as mini LED and micro LED display elements element; and the like. These display elements may have a touch panel function inside the display element.
The liquid crystal display method of the liquid crystal display element includes an IPS method, a VA method, a multi-domain method, an OCB method, an STN method, a TSTN method, and the like. If the display element is a liquid crystal display element, a backlight is required. The backlight is arranged on the opposite side of the liquid crystal display element to the side where the optical layered body is arranged.

Further, the image display device of the present disclosure may be an image display device with a touch panel having a touch panel between the display element and the optical layered body. In this case, it is preferable that the optical layered body is arranged on the outermost surface of the image display device with a touch panel, and that the substrate side of the optical layered body faces the display element side.

The size of the image display device is not particularly limited, but the maximum diameter of the effective display area is preferably 2 inches or more and 500 inches or less.
The effective display area of an image display device is an area in which an image can be displayed. For example, when the image display device has a housing that surrounds the display element, the area inside the housing becomes the effective image area.
The maximum diameter of the effective image area is defined as the maximum length obtained by connecting any two points within the effective image area. For example, if the effective image area is rectangular, the diagonal of the rectangle is the maximum diameter. Also, when the effective image area is circular, the diameter of the circle is the maximum diameter.

Next, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited by these examples. "Parts" and "%" are based on mass unless otherwise specified.

1. Measurement and Evaluation Measurements and evaluations of the optical layered bodies of Examples and Comparative Examples were performed as follows. The atmosphere during each measurement and evaluation was set at a temperature of 23±5° C. and a relative humidity of 40% or more and 65% or less. Moreover, before starting each measurement and evaluation, the target sample was exposed to the atmosphere for 30 minutes or more, and then the measurement and evaluation were performed. Table 2 shows the results.

1-1. Presence or Absence of Region α1 and Region β1 and Percentage of Region α1 Present in Second Region According to the description in the text of the specification, samples with exposed cross sections of the optical laminates of Examples and Comparative Examples were produced. The presence or absence of the region α1 and the region β1 was confirmed from a cross-sectional photograph of the sample taken with a scanning transmission electron microscope. Furthermore, the area ratio between the area α1 and the area α2 and the area ratio between the area β1 and the area β2 were calculated. An independent region α1 exists in the first resin layer 21, a resin contained in the region α1 is different from a resin contained in the region α2, and an independent region β1 exists in the second resin layer 22. That is, the difference between the resin contained in the region β1 and the resin contained in the region β2 can be determined from the difference in brightness in the photograph.
Furthermore, the number-based ratio of the regions α existing in the second region was calculated. In calculating the ratio, a plurality of cross-sectional photographs were taken until the total number of regions α exceeded 50.

1-2. θa1 and θa2, and Pa1 and Pa2
According to the description in the text of the specification, samples of the optical layered bodies of Examples and Comparative Examples with exposed cross sections were produced. θa1 and θa2, and Pa1 and Pa2 were calculated from a cross-sectional photograph of the sample taken with a scanning transmission electron microscope according to the description in the specification.

1-3. Average Thickness of First Resin Layer and Second Resin Layer According to the description in the specification, samples of the optical layered bodies of Examples and Comparative Examples were prepared in which cross sections were exposed. Select 20 arbitrary points from the cross-sectional photograph of the sample taken with a scanning transmission electron microscope, and calculate the average thickness t1 of the first resin layer and the average thickness t2 of the second resin layer from the average value. did.

1-4. Total light transmittance (Tt) and haze (Hz)
The optical laminates of Examples and Comparative Examples were cut into 10 cm squares. After visually confirming that there were no abnormalities such as dust or scratches, the cutting sites were selected at random. Using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory), the total light transmittance of each sample according to JIS K7361-1:1997 and the haze according to JIS K7136:2000 were measured.
In order to stabilize the light source, turn on the power switch of the device and wait at least 15 minutes before performing calibration without setting anything at the entrance opening (the place where the measurement sample is installed). A sample was set and measured. The light incident surface was on the substrate side.

1-5. Adhesion Adhesion of the optical laminates of Examples and Comparative Examples was evaluated by the following method.
Furthermore, the adhesion of the optical laminates of Examples and Comparative Examples was evaluated after the following light resistance test was carried out.
A sample for evaluation was cross-cut into a grid of 10 squares in total, ie, 10 squares vertically and 10 squares horizontally. The cut interval was 1 mm. When cutting, the blade of the cutter was inserted from the second resin layer side, and cross-cut was performed so that the blade of the cutter reached the top of the substrate.
Adhesive tape (manufactured by Nichiban Co., Ltd., product name "Cellotape (registered trademark)") is attached to the surface of the cross-cut sample, and the cross-cut method specified in JIS K 5600-5-6: 1999 is compliant. A peel test was performed. Based on the results of the peel test, adhesion was evaluated according to the following evaluation criteria.
<Evaluation Criteria>
A: Less than 5% of the cross-cut portions where peeling can be confirmed in the lattice pattern.
B: 5% or more and less than 15% of cross-cut portions where peeling can be confirmed in the grid pattern.
C: 15% or more cross-cut portions where peeling can be confirmed in the grid pattern.

<Light resistance test>
Ultraviolet carbon arc lamp type light resistance and weather resistance tester conforming to JIS B7751 (trade name “FAL-AU B” manufactured by Suga Test Instruments Co., Ltd., light source: ultraviolet carbon arc lamp, irradiance: 500 W/m ² , black Panel temperature: 63° C.), the optical laminates of Examples and Comparative Examples were placed in such a way that the resin layer side faced the light source, and the test was carried out for 200 hours.

1-6. Transmission image clarity (JIS K7374:2007 transmission image clarity)
The transmission image clarity of the optical laminates of Examples and Comparative Examples was measured. The light incident surface was on the substrate side. As a measuring device, an image clarity measuring instrument (trade name: ICM-1T) manufactured by Suga Test Instruments Co., Ltd. was used. The sum of the transmitted image sharpness for the four optical comb widths is shown in Table 2 (unit is "%"). Four comb widths of 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm were used.
Further, the transmission image definition was measured in the same manner as described above for the optical layered bodies of Examples and Comparative Examples after the light resistance test. The sum of the transmitted image sharpness for the four optical comb widths is shown in Table 2 (unit is "%").
Table 2 shows the difference in transmission image clarity before and after the lightfastness test (unit: %). A pass level of the difference is 10.0% or less, and among the pass levels, a difference of 5.0% or less is more preferable.

1-7. Antiglare property On the substrate side of the optical laminates of Examples and Comparative Examples, a transparent adhesive layer (Panac) with a thickness of 25 µm (trade name: "Panaclean PD-S1", refractive index: 1.49) was interposed therebetween. A sample was prepared by bonding a black plate (Kuraray Co., Ltd., trade name “Comoglass DFA2CG 502K (black) system”, total light transmittance 0%, thickness 2 mm, refractive index 1.49) (sample size: length 20 cm x width 30 cm). From the center of the first main surface of the sample under a bright room environment (illuminance on the first main surface of the sample is 500 lux or more and 1000 lux or less; illumination: Hf32 type straight tube three-wavelength neutral white fluorescent lamp) 20 test subjects evaluated whether or not the anti-glare property was obtained to such an extent that the reflection of the observers themselves was not disturbing, based on the following criteria. The lighting position at the time of evaluation was 2 m above the horizontal table in the vertical direction. The subjects were in their thirties and healthy with a visual acuity of 0.7 or more.
A: More than 14 people answered that they were good B: More than 7 people and less than 13 people answered that they were good C: Less than 6 people answered that they were good

2. Fabrication of Optical Laminate [Example 1]
(Manufacture of base material)
A copolymer of methyl methacrylate and methyl acrylate was kneaded at 260° C. using a twin-screw extruder to obtain a pellet-like composition (glass transition point: 134° C.). The resulting pellet-like composition was melt-extruded with a T-die (T-die temperature: 260°C) and discharged onto a cooling roll at 130°C. Next, the film was successively biaxially stretched at a stretching temperature of 145° C. in the machine direction and the transverse direction at a draw ratio of 1.5 times. After cooling, an acrylic resin substrate having a thickness of 40 μm was obtained.
(Formation of resin layer)
The resin layer coating liquid of Example 1 in Table 1 was applied onto the acrylic resin base material by a Meyer bar coating method at a coating amount of 6.0 g/m ² , and then at a wind speed of 5 m/s and a temperature of 90°C. was dried for 30 seconds with warm air of 100 rpm, and the first stage of drying was performed. Further, the coating liquid was dried for 30 seconds with hot air at a wind speed of 20 m/s and a temperature of 90° C. to carry out a second stage of drying. Next, in a nitrogen atmosphere with an oxygen concentration of 200 ppm or less, the ionizing radiation-curable resin composition of the resin layer coating liquid is cured by irradiating with ultraviolet rays so that the integrated light amount is 100 mJ/cm ² , and the first A resin layer and a second resin layer were formed to obtain an optical laminate of Example 1. In the present specification, the coating amount means the coating amount after drying.

[Examples 2-4], [Comparative Examples 1-3]
Example 1 was carried out in the same manner as in Example 1, except that the composition of the resin layer coating liquid, the coating amount of the resin layer coating liquid, and the drying conditions of the resin layer coating liquid were changed to the compositions and the like shown in Table 1. Optical laminates of 2 to 4 and Comparative Examples 1 to 3 were obtained.

In Table 1, the hexafunctional urethane acrylate oligomer is Mitsubishi Chemical Corp.'s urethane acrylate oligomer (trade name: Shiko UV-7600B, weight average molecular weight: 1400), and the bifunctional acrylate monomer is tetraethylene glycol diacrylate. The trifunctional acrylate monomer is pentaerythritol triacrylate, the monofunctional acrylate monomer is 4-hydroxybutyl acrylate, and the photopolymerization initiator is IGM Resins B.V.'s trade name "Omnirad 184."

From the results in Table 2, it can be confirmed that the optical layered bodies of Examples can suppress a decrease in adhesion and a change in transmission image clarity after the light resistance test.
On the other hand, in the optical laminate of Comparative Example 1, the first resin layer does not have the region α1. Therefore, in the optical layered body of Comparative Example 1, the affinity between the first resin layer and the second resin layer cannot be improved, and the adhesion after the light resistance test is deteriorated. there were. In Comparative Example 1, since the resin layer coating liquid contains a monofunctional monomer, the compatibility is good. Therefore, it is considered that the formation of the sea-island structure becomes difficult, and the region α1 is not formed.
The optical layered body of Comparative Example 2 has large θa1 and Pa1 and does not satisfy both the conditions 1 and 2. For this reason, the optical layered body of Comparative Example 2 had a sharp change in transmission image clarity after the light resistance test. The reason why Comparative Example 2 does not satisfy the conditions 1 and 2 is that the long drying time causes the resin component to move rapidly between the first resin layer and the second resin layer, and θa2 and Pa2 are reduced. Probably because it got bigger.
The optical layered body of Comparative Example 3 has small θa1 and Pa1 and does not satisfy both the condition 1 and the condition 2. For this reason, the optical layered body of Comparative Example 3 could not have good adhesion after the light resistance test. The optical layered body of Comparative Example 3 had insufficient adhesion before the light resistance test. The reason why Comparative Example 3 does not satisfy Conditions 1 and 2 is considered to be that the resin layer coating liquid does not contain a bifunctional monomer.

10: Substrate 20: Resin layer 21: First resin layer 22: Second resin layer 100: Optical laminate 200: Display element 500: Image display device

Claims (14)

An optical laminate having a resin layer on a substrate,
The resin layer has a first resin layer and a second resin layer from the substrate side,
The first resin layer has a region α1 independent of each other and a region α2 surrounding the region α1, and the resin contained in the region α1 and the resin contained in the region α2 are different,
The second resin layer has a region β1 independent of each other and a region β2 surrounding the region β1, and the resin contained in the region β1 and the resin contained in the region β2 are different,
An optical laminate that satisfies condition 1 or condition 2 below.
<Condition 1>
θa1 indicating the average inclination angle of the surface of the base material facing the resin layer and θa2 indicating the average inclination angle of the surface of the first resin layer facing the second resin layer have a relationship of θa2<θa1. is.
<Condition 2>
Pa1 indicating the arithmetic mean height of the surface of the base material on the resin layer side and Pa2 indicating the arithmetic mean height of the surface of the first resin layer on the second resin layer side satisfy Pa2<Pa1 is the relationship. 2. The optical laminate according to claim 1, wherein θa1 is 5.0 degrees or more and 20.0 degrees or less. 3. The optical layered body according to claim 1, wherein said .theta.a2 is 10.0 degrees or less. 2. The optical laminate according to claim 1, wherein the Pa1 is 0.05 μm or more and 0.25 μm or less. 3. The optical laminate according to claim 1, wherein the Pa2 is 0.15 [mu]m or less. When defining the base material side from the center of the thickness direction of the first resin layer as a first region and the second resin layer side from the center of the thickness direction of the first resin layer as a second region, 6. The optical laminate according to claim 1, wherein 70% or more of said region α1 is present in said second region. The resin contained in the region α1 and the resin contained in the region β2 are substantially the same, and the resin contained in the region α2 and the resin contained in the region β1 are substantially the same. 7. The optical laminate according to any one of 1 to 6. The optical laminate according to any one of claims 1 to 7, wherein the resin layer contains first particles having an average particle size of 0.5 µm or more. The optical laminate according to claim 8, wherein the second resin layer contains the first particles. The optical laminate according to claim 8 or 9, wherein the first particles are organic particles. The optical laminate according to any one of claims 1 to 10, wherein the substrate is an acrylic resin substrate. The optical laminate according to any one of claims 1 to 11, wherein the resin layer contains a cured product of a curable resin composition. A polarizing plate having a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, A polarizing plate, wherein at least one of the first transparent protective plate and the second transparent protective plate is the optical laminate according to any one of claims 1 to 12. An image display device comprising the optical laminate according to any one of claims 1 to 12 on a display element.

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