JP7519786B2 - Optical laminate and method for producing same - Google Patents

Description

The present invention relates to a retardation laminate, an optical laminate, and a method for manufacturing the same.

Organic EL display devices using organic light-emitting diodes (OLEDs) are not only lighter and thinner than liquid crystal display devices, but also offer high image quality with a wide viewing angle, fast response speed, and high contrast, and are therefore used in a variety of fields, including smartphones, televisions, and digital cameras. It is known that in organic EL display devices, the anti-reflection performance is improved by using circular polarizers, etc., to prevent a decrease in visibility due to reflection of external light.

For example, Patent Documents 1 and 2 disclose an optical laminate having an anti-reflection function that is applied to image display panels such as organic EL display devices, in which a polarizing plate including a linear polarizing layer is provided with two retardation layers formed of liquid crystal compounds and laminated to each other via an adhesive layer.

JP 2017-102286 A JP 2015-40953 A

When the liquid crystal compound used in the retardation layer is a polymerizable liquid crystal compound, it is required to increase the degree of polymerization (degree of hardening) in order to improve the optical durability of the retardation layer. When a retardation layer having a high degree of polymerization of a polymerizable liquid crystal compound is laminated with another retardation layer to produce a retardation laminate, and this is used to produce an optical laminate such as a circular polarizing plate, curling may occur in the retardation laminate. Such curling reduces the handleability of the retardation laminate and may cause a decrease in workability in the manufacturing process of the optical laminate.

The present invention aims to provide a retardation laminate, an optical laminate, and a method for producing the same that are easy to handle when producing optical laminates, etc.

The present invention provides the following retardation laminate, optical laminate, and methods for producing the same.
[1] A retardation laminate including a first retardation layer, a first attachment layer, and a second retardation layer in this order,
The first retardation layer includes a first liquid crystal layer which is a cured layer of a polymerizable liquid crystal compound,
The second retardation layer includes a second liquid crystal layer which is a cured layer of a polymerizable liquid crystal compound,
The puncture elastic modulus E1 of the first retardation layer is 35 g f /mm or more,
The retardation laminate, wherein the puncture elastic modulus E1 and the puncture elastic modulus E2 of the second retardation layer satisfy the relationship of the following formula (1).
0.7≦E1/E2≦1.3 (1)
[2] The retardation laminate according to [1], wherein the puncture elastic modulus E2 is 55 g f /mm or less.
[3] The retardation laminate according to [1] or [2], wherein a thickness t1 of the first retardation layer and a thickness t2 of the second retardation layer satisfy the relationship of the following formula (2).
0.1≦t1/t2≦1.3 (2)
[4] The first retardation layer is a laminate of the first liquid crystal layer and a first alignment layer,
The retardation laminate according to any one of [1] to [3], wherein the first alignment layer is provided on the side of the first liquid crystal layer opposite to the first bonding layer.
[5] The second retardation layer is a laminate of the second liquid crystal layer and a second alignment layer,
The retardation laminate according to any one of [1] to [4], wherein the second alignment layer is provided on the side of the second liquid crystal layer opposite to the first bonding layer.
[6] Further, a second base layer is provided on the opposite side of the second retardation layer to the first attachment layer,
The retardation laminate according to any one of [1] to [5], wherein the second base material layer is separably provided between the second base material layer and the second liquid crystal layer.
[7] Further, a first base material layer is provided on the opposite side of the first retardation layer to the first bonding layer,
The retardation laminate according to [6], wherein the first base material layer is separably provided between the first base material layer and the first liquid crystal layer.
[8] An optical laminate having the retardation laminate according to any one of [1] to [6], a second bonding layer, and an optical film in this order,
An optical laminate, wherein the optical film is provided on the first retardation layer side of the retardation laminate via the second attachment layer.
[9] The optical laminate according to [8], wherein the optical film includes a polarizing plate having a protective layer provided on one or both sides of a linear polarizing layer.
[10] A method for producing a retardation laminate including a first retardation layer, a first attachment layer, and a second retardation layer in this order,
A step of preparing a first retardation layer with a base material layer having a first base material layer and the first retardation layer, and a second retardation layer with a base material layer having a second base material layer and the second retardation layer;
The first retardation layer side of the first retardation layer with the base layer and the second retardation layer side of the second retardation layer with the base layer are bonded to each other via the first bonding layer,
the first retardation layer includes a first liquid crystal layer formed by polymerizing a polymerizable liquid crystal compound on the first base layer,
the second retardation layer includes a second liquid crystal layer formed by polymerizing a polymerizable liquid crystal compound on the second base layer,
The puncture elastic modulus E1 of the first retardation layer is 35 g f /mm or more,
The method for producing a retardation laminate, wherein the puncture elastic modulus E1 and the puncture elastic modulus E2 of the second retardation layer satisfy the relationship of the following formula (1).
0.7≦E1/E2≦1.3 (1)
[11] The method for producing a retardation laminate according to [10], wherein a thickness t1 of the first retardation layer and a thickness t2 of the second retardation layer satisfy a relationship of the following formula (2).
0.1≦t1/t2≦1.3 (2)
[12] The method for producing a retardation laminate according to [10] or [11], wherein the first retardation layer with a base layer has a first alignment layer between the first base layer and the first liquid crystal layer.
[13] The second retardation layer with base layer has a second alignment layer between the second base layer and the second liquid crystal layer, the method for producing a retardation laminate according to any one of [10] to [12].
[14] A method for producing an optical laminate including an optical film, a second attachment layer, a first retardation layer, a first attachment layer, and a second retardation layer in this order,
A step of preparing a retardation laminate according to [7] or a retardation laminate produced by the method for producing a retardation laminate according to any one of [10] to [13];
Separating the first base layer from the retardation laminate;
and bonding the optical film to an exposed surface exposed by separating the first base layer via the second bonding layer.
[15] The method for producing an optical laminate according to [14], further comprising a step of separating the second base layer after the step of bonding via the second bonding layer.

The present invention provides a retardation laminate that is easy to handle when manufacturing optical laminates, etc.

FIG. 1 is a schematic cross-sectional view showing an example of a retardation laminate of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of the retardation laminate of the present invention. FIG. 2 is a schematic cross-sectional view showing a still further example of the retardation laminate of the present invention. FIG. 1 is a schematic cross-sectional view showing an example of an optical laminate of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of the optical laminate of the present invention. 1 is a schematic cross-sectional view showing an example of a manufacturing process of the retardation laminate of the present invention.

The retardation laminate, optical laminate, and manufacturing method thereof of the present invention will be described below with reference to the drawings. All of the drawings below are presented to aid in understanding the present invention, and the size and shape of each component shown in the drawings do not necessarily match the size and shape of the actual component.

(Retardation Laminate)
1 to 3 are schematic cross-sectional views showing an example of the retardation laminate of this embodiment. The retardation laminates 1a, 1b, and 1c of this embodiment (hereinafter, these may be collectively referred to as "retardation laminate 1") include a first retardation layer 10, a first bonding layer 30, and a second retardation layer 20 in this order, as shown in FIG. 1 and FIG. 2. The first retardation layer 10 includes a first liquid crystal layer 12 which is a cured layer of a polymerizable liquid crystal compound. The second retardation layer 20 includes a second liquid crystal layer 22 which is a cured layer of a polymerizable liquid crystal compound. The puncture elastic modulus E1 of the first retardation layer 10 is 35 g f /mm or more. The puncture elastic modulus E1 of the first retardation layer 10 and the puncture elastic modulus E2 of the second retardation layer 20 are expressed by the following formula (1):
0.7≦E1/E2≦1.3 (1)
Satisfy the relationship.

The first retardation layer 10 may be the first liquid crystal layer 12 itself, which is a cured layer of a polymerizable liquid crystal compound, or may be a laminate of the first liquid crystal layer 12 and the first alignment layer 11. When the first retardation layer 10 has the first alignment layer 11, the first alignment layer 11 is provided on the side of the first liquid crystal layer 12 opposite to the second retardation layer 20 side.

The puncture modulus E1 of the first retardation layer 10 is 35 g f /mm or more, may be 38 g f /mm or more, may be 40 g f /mm or more, or may be 42 g f /mm or more. The puncture modulus E1 is usually 60 g f /mm or less, may be 55 g f /mm or less, or may be 50 g f /mm or less. The puncture modulus E1 is a value at a temperature of 23 ° C. and a relative humidity of 50%, and can be measured by the method described in the examples below. When the first retardation layer 10 is a laminate of the first liquid crystal layer 12 and the first alignment layer 11, the puncture modulus E1 of the first retardation layer 10 is measured by piercing a needle from the first alignment layer 11 side. In the first retardation layer 10, the temperature dependency of the puncture modulus E1 is not observed in the range of 23 to 80 ° C.

The puncture modulus E1 of the first retardation layer 10 can be adjusted, for example, by the type and degree of polymerization (hardening degree) of the polymerizable liquid crystal compound constituting the first liquid crystal layer 12, the type and amount of additives such as a polymerization initiator, a reactive additive, a leveling agent, a polymerization inhibitor, and a crosslinking agent contained in the first liquid crystal layer 12, the type and degree of polymerization (hardening degree) of the polymerizable compound in the hardening resin composition constituting the first alignment layer 11, and the thickness of the first retardation layer 10. Usually, as the degree of polymerization (hardening degree) increases, the value of the puncture modulus E1 also increases. The puncture modulus E1 of the first retardation layer 10 can also be adjusted by the crosslink density of the first liquid crystal layer 12 and the crosslink density of the first alignment layer 11. For example, in order to increase the crosslink density of the first liquid crystal layer 12, a polyfunctional polymerizable liquid crystal compound having three or more polymerizable groups in the molecule may be used as the polymerizable liquid crystal compound for forming the first liquid crystal layer 12.

In order to set the puncture modulus E1 of the first retardation layer 10 within a predetermined range, for example, a preliminary experiment is performed in which the degree of polymerization (hardening degree) of the polymerizable liquid crystal compound and the degree of polymerization (hardening degree) of the first alignment layer 11 are controlled, and the desired puncture modulus E1 can be obtained. As such a preliminary experiment, for example, when controlling the degree of polymerization of the first liquid crystal layer, it can be performed as follows. First, a coating layer of a liquid crystal layer forming composition containing a polymerizable liquid crystal compound is provided on a first base layer (which may have a first alignment layer), and this coating layer is irradiated with ultraviolet light or the like to form a first liquid crystal layer on the first base layer. The ratio (relative value) of the amount of polymerizable groups of the polymerizable liquid crystal compound contained in the coating layer and the amount of polymerizable groups of the polymerizable liquid crystal compound contained in the first liquid crystal layer is measured by infrared absorption (IR) spectrum measurement or the like to determine the degree of polymerization (hardening degree). The puncture modulus E1 of the first retardation layer including the first liquid crystal layer obtained at this time is measured, and the degree of polymerization and the puncture modulus E1 determined above are related to each other. This procedure is carried out by changing the type of polymerizable liquid crystal compound, the amount of ultraviolet light, etc. In this way, the correlation between the degree of polymerization and the puncture elastic modulus E1 can be obtained, and the degree of polymerization required to obtain the desired puncture elastic modulus E1 can be determined.

The thickness t1 of the first retardation layer 10 is preferably 1.0 μm or more, more preferably 1.5 μm or more, and may be 1.7 μm or more, or may be 2.0 μm or more. The thickness t1 is usually 8 μm or less, and may be 5 μm or less, or may be 3 μm or less.

The second retardation layer 20 may be the second liquid crystal layer 22 itself, which is a cured layer of a polymerizable liquid crystal compound, or may be a laminate of the second liquid crystal layer 22 and the second alignment layer 21. When the second retardation layer 20 has the second alignment layer 21, the second alignment layer 21 is provided on the side of the second liquid crystal layer 22 opposite to the first retardation layer 10 side.

The puncture modulus E2 of the second retardation layer 20 is preferably 55 g f /mm or less, may be 50 g f /mm or less, or may be 45 g f /mm or less. The puncture modulus E2 is usually 5 g f /mm or more, may be 8 g f /mm or more, may be 10 g f /mm or more, or may be 20 g f /mm or more. The puncture modulus E2 is a value at a temperature of 23 ° C. and a relative humidity of 50%, and can be measured by the method described in the examples described later. When the second retardation layer 20 is a laminate of the second liquid crystal layer 22 and the second alignment layer 21, the puncture modulus E2 of the second retardation layer 20 is measured by piercing a needle from the second alignment layer 21 side. In the second retardation layer 20, the temperature dependency of the puncture modulus E2 is not observed in the range of 23 to 80 ° C.

The puncture modulus E2 of the second retardation layer 20 can be adjusted, for example, by the type and degree of polymerization (hardening degree) of the polymerizable liquid crystal compound constituting the second liquid crystal layer 22, the type and amount of additives such as a polymerization initiator, a reactive additive, a leveling agent, a polymerization inhibitor, and a crosslinking agent contained in the second liquid crystal layer 22, the type and degree of polymerization (hardening degree) of the polymerizable compound in the hardening resin composition constituting the second alignment layer 21, the thickness of the second retardation layer 20, etc. Usually, as the degree of polymerization (hardening degree) increases, the value of the puncture modulus E2 also increases. The puncture modulus E2 of the second retardation layer 20 can also be adjusted by the crosslink density of the second liquid crystal layer 22 and the crosslink density of the second alignment layer 21. For example, in order to increase the crosslink density of the second liquid crystal layer 22, a polyfunctional polymerizable liquid crystal compound having three or more polymerizable groups in the molecule may be used as the polymerizable liquid crystal compound for forming the second liquid crystal layer 22.

The method of the preliminary experiment to set the puncture elastic modulus E2 of the second phase difference layer 20 within a predetermined range can be the same as the method of the preliminary experiment to set the puncture elastic modulus E1 of the first phase difference layer to a desired range.

The thickness t2 of the second retardation layer 20 is preferably 1.0 μm or more, and may be 1.5 μm or more, 2.0 μm or more, or 2.5 μm or more. The thickness t2 is usually 8 μm or less, and may be 5 μm or less, 3.5 μm or less, or 3.0 μm or less.

The retardation laminate 1 may have a second base layer 25 on the side opposite to the first bonding layer 30 side of the second retardation layer 20, as in the retardation laminates 1b and 1c shown in Figures 2 and 3. The second base layer 25 is preferably provided in direct contact with the second retardation layer 20. The second base layer 25 is preferably provided separably between the second base layer 25 and the second liquid crystal layer 22. Separable between the second base layer 25 and the second liquid crystal layer 22 means that the second base layer 25 is peelable from the second liquid crystal layer 22, or, if the second alignment layer 21 is present between the second base layer 25 and the second liquid crystal layer 22, that the second alignment layer 21 is peelable from the second liquid crystal layer 21, or that the second alignment layer 21 is peelable from the second liquid crystal layer 22. Therefore, if the second substrate layer 25 is peelable from the second alignment layer 21, when the second substrate layer 25 is separated from the optical laminate 5a (FIG. 4) described below, the second alignment layer 21 remains on the second liquid crystal layer 22. If the second alignment layer 21 is peelable from the second liquid crystal layer 22, when the second substrate layer 25 is separated from the optical laminate 1a, the second alignment layer 21 is peeled off together with the second substrate layer 25.

The retardation laminate 1 may have a first substrate layer 15 on the side opposite to the first bonding layer 30 of the first retardation layer 10 in addition to the second substrate layer 25, as in the retardation laminate 1c shown in FIG. 3. The first substrate layer 15 is preferably provided in direct contact with the first retardation layer 10. The first substrate layer 15 is preferably provided separably between the first substrate layer 15 and the first liquid crystal layer 12. Separable between the first substrate layer 15 and the first liquid crystal layer 12 means that the first substrate layer 15 is peelable from the first liquid crystal layer 12, or, if a first alignment layer 11 is present between the first substrate layer 15 and the first liquid crystal layer 12, that the first alignment layer 11 is peelable from the first liquid crystal layer 12, or that the first alignment layer 11 is peelable from the first liquid crystal layer 12. Therefore, if the first substrate layer 15 is peelable from the first alignment layer 11, when the first substrate layer 15 is separated from the retardation laminate 1c, the first alignment layer 11 remains on the first liquid crystal layer 12. If the first alignment layer 11 is peelable from the first liquid crystal layer 12, when the first substrate layer 15 is separated from the retardation laminate 1c, the first alignment layer 11 is peeled off together with the first substrate layer 15.

The first bonding layer 30 is a layer for bonding the first phase difference layer 10 and the second phase difference layer 20. The first bonding layer 30 can be in direct contact with the first phase difference layer 10 and the second phase difference layer 20. The first bonding layer 30 is an adhesive layer or an adhesive cured layer.

In the retardation laminate 1, the puncture elastic modulus E1 of the first retardation layer 10 and the puncture elastic modulus E2 of the second retardation layer 20 satisfy the relationship of the above formula (1). E1/E2 is 0.7 or more, may be 0.9 or more, or may be 1.0 or more. E1/E2 is 1.3 or less, may be 1.2 or less, or may be 1.1 or less.

The first liquid crystal layer 12 may be formed by applying a liquid crystal layer forming composition containing a polymerizable liquid crystal compound on the first substrate layer 15 through the first alignment layer 11 or without the first alignment layer 11, drying the composition, and polymerizing and curing the polymerizable liquid crystal compound. Similarly, the second liquid crystal layer 22 may be formed by applying a liquid crystal layer forming composition containing a polymerizable liquid crystal compound on the second substrate layer 25 through the second alignment layer 21 or without the second alignment layer 21, drying the composition, and polymerizing and curing the polymerizable liquid crystal compound. In this case, it is considered that the first liquid crystal layer 12 and the second liquid crystal layer 22 have residual shrinkage stress caused by the drying or curing associated with the polymerization. In addition, when the first retardation layer 10 includes the first alignment layer 11 formed using a polymerizable compound, and when the second retardation layer 20 includes the second alignment layer 21 formed using a polymerizable compound, it is considered that the first retardation layer 10 and the second retardation layer 20 also have residual shrinkage stress caused by the curing associated with the polymerization of the polymerizable compound.

The shrinkage stress remaining in the first retardation layer 10 (first liquid crystal layer 12, first alignment layer 11) is suppressed to some extent by the first base layer 15 when the first retardation layer 10 is present on the first base layer 15. This shrinkage stress is released by separating the first base layer 15 from the retardation laminate 1c in the manufacturing process of the retardation laminate 1b or the manufacturing process of the optical laminates 5a, 5b (Figures 4 and 5) described later. Similarly, the shrinkage stress remaining in the second retardation layer 20 (second liquid crystal layer 22, second alignment layer 21) is suppressed to some extent by the second base layer 25 when the second retardation layer 20 is present on the second base layer 25. This shrinkage stress is also released by separating the second base layer 25 included in the retardation laminate 1b in the manufacturing process of the optical laminate 5a described later. Therefore, if the degree of shrinkage on both sides of the retardation laminates 1a and 1b differs significantly due to the shrinkage stress released by the separation of the first base layer 15 and/or the second base layer 25, it is believed that a large amount of curl will occur in the retardation laminates 1a and 1b.

The shrinkage stress remaining in the retardation layers such as the first retardation layer 10 and the second retardation layer 20 tends to increase as the degree of polymerization (degree of curing) of the polymerizable liquid crystal compound and the polymerizable compound increases. Therefore, it is considered that the larger the puncture elastic modulus E1 of the first retardation layer 10 and the puncture elastic modulus E2 of the second retardation layer 20, the larger the shrinkage stress.

In the phase difference laminate 1, the puncture elastic modulus E1 and E2 are set to satisfy the relationship of the above formula (1), so it is considered that the difference between the contraction stress of the first phase difference layer 10 and the contraction stress of the second phase difference layer 20 is suppressed. Therefore, even when using a first phase difference layer 10 whose puncture elastic modulus E1 is in the above range and whose contraction stress is considered to be large, it is possible to suppress curling that occurs in the phase difference laminates 1a and 1b during the manufacturing process of the optical laminates 5a and 5b described below. This improves the handleability of the phase difference laminates 1a and 1b and suppresses a decrease in workability during the manufacture of the optical laminates 5a and 5b.

The thickness t1 of the first retardation layer 10 and the thickness t2 of the second retardation layer 20 are expressed by the following formula (2):
0.1≦t1/t2≦1.3 (2)
It is preferable that the relationship is satisfied. t1/t2 may be 0.3 or more, 0.5 or more, or 0.6 or more. t1/t2 may be 1.2 or less, 1.0 or less, or 0.8 or less.

It is considered that the greater the thickness of the first phase difference layer 10, the greater the contraction stress of the first phase difference layer 10 released when the first base layer 15 is separated. Similarly, for the second phase difference layer 20, it is considered that the greater the thickness, the greater the contraction stress released when the second base layer 25 is separated. Therefore, in the phase difference laminate 1, it is considered that the difference between the contraction stress of the first phase difference layer 10 and the contraction stress of the second phase difference layer 20 can be further reduced by making the thicknesses t1 and t2 satisfy the relationship of the above formula (2). Therefore, even when the first phase difference layer 10 having the puncture elastic modulus E1 in the above range is used, curling that occurs in the phase difference laminates 1a and 1b in the manufacturing process of the optical laminates 5a and 5b described later can be suppressed. This improves the handleability of the phase difference laminates 1a and 1b, and suppresses a decrease in workability during the manufacturing of the optical laminates 5a and 5b.

The MD curl value and TD curl value representing the curl amount of the retardation laminate 1a shown in FIG. 1 are both preferably within ±20 mm, more preferably within ±15 mm, and may be within ±13 mm. At least one of the MD curl value and TD curl value of the retardation laminate 1a may be within ±13 mm, or may be within ±10 mm. The MD curl value and the TD curl value are the curl value in the film transport direction and the curl value in the direction perpendicular to the film transport direction, respectively, and can be determined by the method described in the examples below.

(Optical laminate)
4 and 5 are schematic cross-sectional views showing an example of the optical laminate of this embodiment. The optical laminates 5a and 5b of this embodiment (hereinafter, both may be collectively referred to as "optical laminate 5") have the retardation laminate 1a shown in FIG. 1 or the retardation laminate 1b shown in FIG. 2, a second bonding layer 32, and an optical film 40 in this order. In the optical laminate 5, the optical film 40 is provided on the first retardation layer 10 side of the retardation laminates 1a and 1b via the second bonding layer 32. As described above, the retardation laminates 1a and 1b may or may not include the first alignment layer 11, and may or may not include the second alignment layer 21.

As described above, even if the puncture elastic modulus E1 of the first retardation layer 10 is within the above range, the puncture elastic modulus E1 and the puncture elastic modulus E2 are in the relationship of formula (1) above, so that curling occurring in the retardation laminates 1a and 1b can be suppressed. This is expected to suppress curling occurring in the optical laminates 5a and 5b.

Examples of the optical film 40 include a linear polarizing layer; a polarizing plate having a protective layer on one or both sides of the linear polarizing layer; a polarizing plate with a protective film on one side of the polarizing plate; a reflective film; a semi-transmissive reflective film; a brightness enhancing film; an optical compensation film; and a film with an anti-glare function. One or more of these may be used in combination. The optical film 40 preferably includes at least a linear polarizing layer, and more preferably includes a polarizing plate. When the optical film 40 includes a polarizing plate having a protective layer only on one side of the linear polarizing layer, it is preferable that the linear polarizing layer side of the polarizing plate and the retardation laminate 1a, 1b are bonded together. When the optical film includes a polarizing plate with a protective film, it is preferable that the polarizing plate side of the polarizing plate with the protective film and the retardation laminate 1a, 1b are bonded together.

The second bonding layer 32 is a layer for bonding the retardation laminates 1a and 1b to the optical film 40. The second bonding layer 32 can be in direct contact with the first retardation layer 10 and the optical film 40 of the retardation laminates 1a and 1b. The second bonding layer 32 is an adhesive layer or an adhesive cured layer.

The optical laminate 5b may further have a third bonding layer and a release film (not shown) in this order on the second retardation layer 20 side. The third bonding layer can be used to bond the optical laminate 5b to an image display element of a display device. The third bonding layer is a pressure-sensitive adhesive layer or an adhesive cured layer. The release film is a film that can be peeled off from the third bonding layer, and can cover and protect the surface of the third bonding layer until the third bonding layer is used.

The optical laminate 5 may be a circular polarizing plate. In this case, the optical film includes a linear polarizing layer, a polarizing plate, or a polarizing plate with a protective film, and at least one of the first retardation layer 10 and the second retardation layer 20 is preferably a quarter-wave retardation layer. When the optical laminate 5 is a circular polarizing plate, the layer structure of the optical laminate 5 may be, when the optical film is a polarizing plate, [i] a polarizing plate, a half-wave retardation layer, and a quarter-wave retardation layer in this order, [ii] a polarizing plate, a quarter-wave retardation layer with reverse wavelength dispersion, and a positive C plate in this order, or [iii] a polarizing plate, a positive C plate, and a quarter-wave retardation layer with reverse wavelength dispersion in this order.

The optical laminate 5 can be used, for example, by being attached to the image display element of a liquid crystal display device or an organic EL (electroluminescence) display device.

(Method of manufacturing retardation laminate)
6 is a schematic cross-sectional view showing an example of a manufacturing process of the retardation laminate of this embodiment. The manufacturing method of the retardation laminate 1 includes the first retardation layer 10 and the second retardation layer 20 described above, the first retardation layer 10 has the puncture elastic modulus E1 described above, and the first retardation layer 10 and the second retardation layer 20 satisfy the relationship of the ratio (E1/E2) described above. The manufacturing method of the retardation laminate 1 is as follows:
A step of preparing a base layer-attached first phase difference layer 18 having a first base material layer 15 and a first phase difference layer 10, and a base layer-attached second phase difference layer 28 having a second base material layer 25 and a second phase difference layer 20 (FIGS. 6A and 6B);
The method includes a step of bonding the first phase difference layer 10 side of the first phase difference layer 18 with the base layer and the second phase difference layer 20 side of the second phase difference layer 28 with the base layer via a first bonding layer 30 (FIG. 6(c)).

The first retardation layer 10 includes a first liquid crystal layer 12 formed by polymerizing a polymerizable liquid crystal compound on a first substrate layer 15, and the second retardation layer 20 includes a second liquid crystal layer 22 formed by polymerizing a polymerizable liquid crystal compound on a second substrate layer 25. Therefore, the process of preparing the first retardation layer 18 with a substrate layer may include a process of polymerizing a polymerizable liquid crystal compound on the first substrate layer 15 to form the first liquid crystal layer 12. In addition, the process of preparing the second retardation layer 28 with a substrate layer may include a process of polymerizing a polymerizable liquid crystal compound on the second substrate layer 25 to form the second liquid crystal layer 22.

The first liquid crystal layer 12 may be formed by polymerizing a polymerizable liquid crystal compound on the first alignment layer 11 provided on the first substrate layer 15. Similarly, the second liquid crystal layer 22 may be formed by polymerizing a polymerizable liquid crystal compound on the second alignment layer 21 provided on the second substrate layer 25. In this case, the step of preparing the substrate layer-attached first retardation layer 18 may include a step of forming the first alignment layer 11 on the first substrate layer 15. Also, the step of preparing the substrate layer-attached second retardation layer 28 may include a step of forming the second alignment layer 21 on the second substrate layer 25.

In the process of laminating via the first laminating layer 30, for example, first, a first laminating composition layer for forming the first laminating layer 30 is formed on the first phase difference layer 10 side of the first phase difference layer 18 with the base layer, and/or the second phase difference layer 20 side of the second phase difference layer 28 with the base layer. Next, the first laminating layer 30 is formed from the first laminating composition layer. The method for forming the first laminating layer 30 from the first laminating composition layer may be selected according to the type of the first laminating composition layer. For example, when the laminating composition is an adhesive composition, the first laminating layer 30 may be formed by curing the laminating agent by irradiating with active energy rays or performing a heat treatment, etc., and when the first laminating composition is a pressure-sensitive adhesive composition, the first laminating composition layer may be the first laminating layer 30. This makes it possible to obtain a retardation laminate 1c in which the first base layer 15, the first retardation layer 10, the first bonding layer 30, the second retardation layer 20, and the second base layer 25 are laminated in this order, as shown in FIG. 6(c) and FIG. 3.

The method for manufacturing the retardation laminate 1 may further include a step of separating the first base layer 15 from the retardation laminate 1c. This makes it possible to obtain a retardation laminate 1b in which the first retardation layer 10, the first bonding layer 30, the second retardation layer 20, and the second base layer 25 are laminated in this order, as shown in FIG. 2.

As described above, even if the puncture elastic modulus E1 of the first retardation layer 10 is within the above range, the puncture elastic modulus E1 and the puncture elastic modulus E2 are in the relationship of formula (1) above, so that curling occurring in the retardation laminate 1b can be suppressed. This makes it possible to suppress a decrease in workability during the manufacture of the optical laminate 5 described later.

(Method for producing optical laminate)
The method for producing the optical laminate 5 includes the steps of:
A step of preparing a retardation laminate 1c shown in FIG. 3 (a first base layer 15, a first retardation layer 10, a first bonding layer 30, a second retardation layer 20, and a second base layer 25 laminated in this order);
A step of separating the first base layer 15 from the retardation laminate 1c;
and bonding a first exposed surface (exposed surface) exposed by separating the first base layer 15 to the optical film 40 via a second bonding layer 32 .

The method for producing the optical laminate 5 may further include a step of separating the second base layer 25 after the step of bonding via the second bonding layer 32. The method for producing the optical laminate 5 may further include a step of forming a third bonding layer on the second exposed surface exposed by the step of separating the second base layer 25.

The process of preparing the phase difference laminate 1c may include a process of manufacturing the phase difference laminate 1c by the above-mentioned method for manufacturing the phase difference laminate 1.

The process of separating the first base layer 15 is a process of separating the first base layer 15 from the retardation laminate 1c shown in FIG. 3 to obtain a retardation laminate 1b in which the first retardation layer 10, the first bonding layer 30, the second retardation layer 20, and the second base layer 25 are laminated in this order as shown in FIG. 2. The separation of the first base layer 15 may involve peeling off only the first base layer 15, or, if the retardation laminate 1c includes a first alignment layer 11, may involve peeling off the first alignment layer 11 together with the first base layer 15. This allows the first base layer 15 to be separated from the first liquid crystal layer 12 included in the first retardation layer 10.

The process of bonding via the second bonding layer 32 is a process of bonding the first exposed surface exposed by separating the first base layer 15 from the retardation laminate 1c to the optical film 40. The first exposed surface can be the first liquid crystal layer 12 or the first alignment layer 11, depending on whether the retardation laminate 1c includes the first alignment layer 11 or not, and whether the first alignment layer 11 is peeled off by separating the first base layer 15 or not.

In the step of laminating via the second laminating layer 32, for example, first, a second laminating composition layer for forming the second laminating layer 32 is formed on the first exposed surface side and/or the optical film 40 side. Next, the second laminating layer 32 is formed from the second laminating composition layer. The method for forming the second laminating layer 32 from the second laminating composition layer may be selected according to the type of the second laminating composition layer. For example, when the second laminating composition is an adhesive composition, the second laminating layer 32 may be formed by curing the laminating agent by irradiating with active energy rays or performing a heat treatment, etc., and when the second laminating composition is a pressure-sensitive adhesive composition, the second laminating composition layer may be used as the second laminating layer 32. This allows the optical laminate 5a shown in FIG. 4 to be obtained.

The process of separating the second substrate layer 25 is a process of separating the second substrate layer 25 from the optical laminate 5a. When separating the second substrate layer 25, only the second substrate layer 25 may be peeled off, or, if the retardation laminates 1b and 1c include the second alignment layer 21, the second alignment layer 21 may also be peeled off together with the second substrate layer 25.

The process of forming the third bonding layer is a process of forming a third bonding layer on the second exposed surface exposed by separating the second base layer 25 from the optical laminate 5a. Only the third bonding layer may be formed, or a laminate structure may be formed in which the third bonding layer and the release film are laminated in this order. The second exposed surface can be the second liquid crystal layer 22 or the second alignment layer 21, depending on whether the optical laminate 5a includes the second alignment layer 21 or not, and whether the second alignment layer 21 is peeled off by separating the second base layer 25 or not.

The third bonding layer is preferably a pressure-sensitive adhesive layer. In this case, the step of forming the third bonding layer may be performed by bonding the third bonding layer side of the bonding layer with a release film, in which the third bonding layer is formed on a release film, to the second exposed surface. This makes it possible to obtain an optical laminate 1 in which a release film that covers and protects the third bonding layer is provided on the side of the third bonding layer opposite the second retardation layer 20.

As described above, even if the puncture elastic modulus E1 of the first phase difference layer 10 is within the above range, the puncture elastic modulus E1 and the puncture elastic modulus E2 are in the relationship of formula (1) above, so that curling occurring in the phase difference laminates 1a and 1b can be suppressed. This is expected to suppress a decrease in workability during the manufacture of the optical laminate 5, and to suppress curling occurring in the optical laminates 5a and 5b.

The following describes in detail the retardation laminate and optical laminate of this embodiment, as well as the components used in their manufacturing methods.

(First retardation layer, second retardation layer)
The first retardation layer and the second retardation layer (hereinafter, both may be collectively referred to as "retardation layers") are layers having retardation properties, and are each a cured product layer of a polymerizable liquid crystal compound. The first retardation layer may have a first alignment layer in addition to the first liquid crystal layer. The second retardation layer may also have a first alignment layer. In addition to the two liquid crystal layers, there may be a second alignment layer.

(First liquid crystal layer, second liquid crystal layer)
The first liquid crystal layer and the second liquid crystal layer (hereinafter, both may be collectively referred to as "liquid crystal layers") are layers of a cured product of a polymerizable liquid crystal compound. A liquid crystal compound and a disc-shaped polymerizable liquid crystal compound can be used. Either one of them may be used, or a mixture containing both of them may be used. When the polymerizable liquid crystal compound is aligned horizontally or vertically with respect to the first substrate layer or the second substrate layer, the optical axis of the polymerizable liquid crystal compound coincides with the long axis direction of the polymerizable liquid crystal compound. When the polymerizable liquid crystal compound is aligned, the optical axis of the polymerizable liquid crystal compound is in a direction perpendicular to the disk surface of the polymerizable liquid crystal compound. The one described in Table 11-513019 (claim 1, etc.) can be suitably used. Examples of the discotic polymerizable liquid crystal compound include those described in JP-A-2007-108732 (paragraphs [0020] to [0067], etc.) and JP-A-2010-244038 (paragraphs [0013] to [0108], etc.). Those can be suitably used.

In order for the liquid crystal layer formed by polymerizing the polymerizable liquid crystal compound to exhibit an in-plane retardation, the polymerizable liquid crystal compound may be aligned in an appropriate direction. When the polymerizable liquid crystal compound is rod-shaped, the in-plane retardation is exhibited by aligning the optical axis of the polymerizable liquid crystal compound horizontally to the plane of the base layer, in which case the optical axis direction and the slow axis direction coincide. When the polymerizable liquid crystal compound is disc-shaped, the in-plane retardation is exhibited by aligning the optical axis of the polymerizable liquid crystal compound horizontally to the plane of the base layer, in which case the optical axis and the slow axis are perpendicular to each other. The alignment state of the polymerizable liquid crystal compound can be adjusted by the combination of the alignment layer and the polymerizable liquid crystal compound.

A polymerizable liquid crystal compound is a compound having at least one polymerizable group and liquid crystal properties. When two or more types of polymerizable liquid crystal compounds are used in combination, it is preferable that at least one type has two or more polymerizable groups in the molecule. The polymerizable group means a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can participate in a polymerization reaction by an active radical or acid generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, an oxetanyl group, a styryl group, and an allyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystallinity of the polymerizable liquid crystal compound may be thermotropic or lyotropic liquid crystal, and when thermotropic liquid crystals are classified according to the degree of order, they may be nematic or smectic liquid crystals.

The thickness of the liquid crystal layer is not particularly limited, but is preferably 0.5 μm or more, may be 1 μm or more, and is usually 8 μm or less, may be 5 μm or less, and is preferably 3 μm or less.

(First alignment layer, second alignment layer)
The first alignment layer and the second alignment layer (hereinafter, both may be collectively referred to as "alignment layers") have an alignment regulating force that aligns the polymerizable liquid crystal compound contained in the liquid crystal layer formed on these alignment layers in a desired direction. It is preferable that the alignment layer has solvent resistance that does not dissolve the liquid crystal layer-forming composition described later by coating, etc., and has heat resistance to removal of the solvent and heat treatment for orienting the polymerizable liquid crystal compound.

The alignment layer may be a vertical alignment layer in which the molecular axis of the polymerizable liquid crystal compound is aligned vertically with respect to the substrate layer, a horizontal alignment layer in which the molecular axis of the polymerizable liquid crystal compound is aligned horizontally with respect to the substrate layer, or an inclined alignment layer in which the molecular axis of the polymerizable liquid crystal compound is aligned at an angle with respect to the substrate layer. The first alignment layer and the second alignment layer may be the same alignment layer or different alignment layers.

Examples of the alignment layer include an alignment polymer layer formed from an alignment polymer, a photoalignment polymer layer formed from a photoalignment polymer, and a groove alignment layer having a concave-convex pattern or multiple grooves on the layer surface. The first alignment layer and the second alignment layer may be the same type of layer or different types of layers.

The oriented polymer layer can be formed by applying a composition in which an oriented polymer is dissolved in a solvent to a substrate layer (first substrate layer or second substrate layer), removing the solvent, and performing a rubbing treatment as necessary. In this case, the orientation control force of the oriented polymer layer formed from the oriented polymer can be adjusted as desired by adjusting the surface condition of the oriented polymer and the rubbing conditions.

The photoalignable polymer layer can be formed by applying a composition containing a polymer or monomer having a photoreactive group and a solvent to a substrate layer (first substrate layer or second substrate layer) and irradiating it with light such as ultraviolet light. In particular, when an alignment control force is to be exerted in the horizontal direction, the layer can be formed by irradiating it with polarized light. In this case, the alignment control force in the photoalignable polymer layer can be adjusted as desired by adjusting the conditions for irradiating the photoalignable polymer with polarized light, etc.

The groove alignment layer can be formed, for example, by a method of forming a concave-convex pattern by exposing the surface of a photosensitive polyimide film through an exposure mask having slits in a pattern shape, developing, etc., a method of forming an uncured layer of active energy ray curable resin on a plate-shaped master having grooves on its surface, transferring this layer to a substrate layer (first substrate layer or second substrate layer) and curing it, or a method of forming an uncured layer of active energy ray curable resin on a substrate layer, and pressing a roll-shaped master having concave-convex shapes against this layer to form concave-convex shapes and then curing it.

From the viewpoint that the alignment layer can be easily peeled off and removed together with the substrate layer when the alignment layer is peeled off and removed together with the substrate layer, it is preferable that the alignment layer contains a resin formed by polymerizing a polymerizable compound. The above-mentioned polymerizable compound is a compound having a polymerizable group, and is usually a non-liquid crystal polymerizable non-liquid crystal compound that does not become liquid crystal. The polymerizable groups of the polymerizable compound react with each other to polymerize the polymerizable compound, thereby forming a resin.

When the orientation layer is to be peeled off and removed together with the substrate layer, it is preferable that the orientation layer contains a resin that is a cured product obtained by curing a known monofunctional or polyfunctional (meth)acrylate monomer in the presence of a polymerization initiator. Examples of (meth)acrylate monomers include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono 2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, urethane acrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol polyacrylate, and dipentaerythritol hexaacrylate. The resin may be one of these or a mixture of two or more of these. When such a resin is used as the alignment layer, after the liquid crystal layer is formed, before or after the step of laminating the obtained laminate with other layers such as a polarizing plate, when the substrate layer is separated from the retardation layer with the substrate layer (the first retardation layer with the substrate layer or the second retardation layer with the substrate layer), the alignment layer can be peeled off and removed together with the substrate layer. In this specification, "(meth)acrylic" means that it may be either acrylic or methacrylic. The "(meth)" in (meth)acrylate, etc., has the same meaning.

When the alignment layer is not peeled off together with the substrate layer and remains on the liquid crystal layer side, it is preferable that the alignment layer contains a resin such as a cured product obtained by curing a trifunctional or higher (meth)acrylate monomer, an imide monomer, or a vinyl ether monomer, and it is more preferable that the alignment layer contains a cured product obtained by curing a trifunctional or higher (meth)acrylate monomer.

When the alignment layer is formed by curing the polymerizable compound in the composition for forming an alignment layer by irradiation with ultraviolet light, the light irradiation intensity of the ultraviolet light is not particularly limited, but is preferably 10 to 1,000 mW/cm ² , and more preferably 100 to 600 mW/cm ^2. If the light irradiation intensity of the composition for forming an alignment layer applied on the substrate layer is less than 10 mW/cm ² , the reaction time becomes too long, and if it exceeds 1,000 mW/cm ² , the heat radiated from the light source may cause wrinkles in the substrate layer, resulting in uneven phase difference. The irradiation intensity is an intensity in a wavelength region effective for activating a polymerization initiator, preferably a photoradical polymerization initiator, more preferably an intensity in a wavelength region of 400 nm or less, and even more preferably an intensity in a wavelength region of 280 to 320 nm. It is preferable to set the cumulative light amount to be 10 mJ/cm ² or more, preferably 100 to 1,000 mJ/cm ² , more preferably 400 to 1,000 mJ/cm ² , even more preferably 600 to 1,000 mJ/cm ² , and even more preferably 600 to 1,000 mJ/cm ² , by irradiating with such light irradiation intensity once or multiple times. If the cumulative light amount applied to the composition for forming an alignment layer applied to the base layer is less than 10 mJ/cm ² , the generation of active species derived from the polymerization initiator is insufficient, and the curing of the composition for forming an alignment layer is insufficient. If the cumulative light amount exceeds 1,000 mJ/cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity. The wavelength of light irradiation (UVA (320 to 390 nm), UVB (280 to 320 nm), etc.) varies depending on the thickness and type of the base layer, the types of components contained in the composition for forming an alignment layer, and the combination of components in the composition for forming an alignment layer, and the like, and the integrated amount of light required also changes depending on the wavelength of light irradiation.

When the polymerizable compound in the composition for forming the alignment layer is cured by UV irradiation, the temperature during UV irradiation is preferably 25°C or higher, more preferably 50°C or higher, and even more preferably 80°C or higher, from the viewpoint of sufficiently increasing the degree of polymerization. In addition, if the temperature is too high, wrinkles may occur in the base layer, and there is a concern that uneven phase difference may occur. Therefore, the temperature during UV irradiation is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 120°C or lower. The above upper and lower limits can be combined in any combination.

The thickness of the alignment layer is not particularly limited, but is preferably 0.01 μm or more, may be 0.05 μm or more, may be 0.1 μm or more, and is usually 5 μm or less, may be 2.5 μm or less, or may be 1 μm or less.

(First Retardation Layer with Base Layer, Second Retardation Layer with Base Layer)
The first retardation layer with a substrate layer and the second retardation layer with a substrate layer (hereinafter, both may be collectively referred to as "substrate layer-attached retardation layers") can be obtained by applying a liquid crystal layer-forming composition containing a polymerizable liquid crystal compound onto the substrate layer, drying it, and polymerizing the polymerizable liquid crystal compound to form a liquid crystal layer, which is a cured layer formed by polymerizing the polymerizable liquid crystal compound. When an alignment layer is formed on the substrate layer, the liquid crystal layer-forming composition may be applied onto the alignment layer, and when the liquid crystal layer has a multilayer structure of two or more layers, the liquid crystal layer-forming composition may be applied sequentially to form a multilayer structure. The above-mentioned method may be used to form the alignment layer.

The liquid crystal layer forming composition usually contains a solvent in addition to the polymerizable liquid crystal compound. The liquid crystal layer forming composition may further contain a polymerization initiator, a reactive additive, a polymerization inhibitor, etc. Each of these components may be used alone or in combination of two or more.

As a solvent that may be contained in a composition containing a polymerizable liquid crystal compound, a solvent capable of dissolving the polymerizable liquid crystal compound and being inactive in the polymerization reaction of the polymerizable liquid crystal compound is preferable.

Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, and phenol; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, methyl amyl ketone, methyl isobutyl ketone, and N-methyl-2-pyrrolidinone; non-chlorinated aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; non-chlorinated aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as propylene glycol monomethyl ether, tetrahydrofuran, and dimethoxyethane; and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. The solvents may be used alone or in combination.

The content of the solvent in the polymerizable liquid crystal composition is usually preferably 10 parts by mass to 10,000 parts by mass, and more preferably 50 parts by mass to 5,000 parts by mass, per 100 parts by mass of the solid content. The solid content means the total of the components other than the solvent in the polymerizable liquid crystal composition.

The polymerization initiator that may be contained in the composition containing the polymerizable liquid crystal compound is a compound that can initiate the polymerization reaction of the polymerizable liquid crystal compound, and a photopolymerization initiator is preferred because it can initiate the polymerization reaction under lower temperature conditions. Specifically, photopolymerization initiators that can generate active radicals or acids under the action of light are included, and among these, photopolymerization initiators that generate radicals under the action of light are preferred. Examples of photoradical polymerization initiators include benzoin compounds, benzophenone compounds, benzil ketal compounds, α-hydroxyketone compounds, α-aminoketone compounds, oxime compounds, triazine compounds, iodonium salts, and sulfonium salts. As the photoradical polymerization initiator, only one type may be used, or two or more types may be used in combination.

Commercially available products may be used as the photoradical polymerization initiator. Specific examples of such commercially available products include Irgacure (registered trademark) 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369, Irgacure 379, Irgacure 127, Irgacure 2959, Irgacure 754, Irgacure 379EG (all manufactured by BASF Japan Ltd.), Seikuol BZ, Seikuol Z, Seikuol BEE (all manufactured by Seiko Chemical Co., Ltd.), and Kayacure. (Kayacure) BP100 (manufactured by Nippon Kayaku Co., Ltd.), Kayacure UVI-6992 (manufactured by Dow), Adeka Optomer SP-152, Adeka Optomer SP-170, Adeka Optomer N-1717, Adeka Optomer N-1919, Adeka Arcles NCI-831, Adeka Arcles NCI-930 (all manufactured by ADEKA Corporation), TAZ-A, TAZ-PP (all manufactured by Nippon SiberHegner AG), and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.).

The content of the polymerization initiator is usually 0.1 to 30 parts by mass, preferably 1 to 20 parts by mass, and more preferably 1 to 15 parts by mass, relative to 100 parts by weight of the total amount of the polymerizable liquid crystal compound. Within this range, the reaction of the polymerizable group proceeds sufficiently, and the alignment state of the polymerizable liquid crystal compound is easily stabilized.

The crosslinking agent that may be contained in the composition containing the polymerizable liquid crystal compound is a compound having one or more photo- or heat-reactive groups in the molecule. By using the crosslinking agent, the crosslink density of the liquid crystal layer changes, making it easier to adjust the film strength. Examples of the crosslinking agent include polyfunctional acrylate compounds, epoxy compounds, oxetane compounds, methylol compounds, isocyanate compounds, etc. Among them, polyfunctional acrylate compounds are preferred from the viewpoint of uniformity of the coating film and adjustment of film strength. The crosslinking agent preferably has 2 to 8 reactive groups in the molecule, and more preferably has 2 to 6 polymerizable groups in the molecule.

Commercially available products may be used as the polyfunctional acrylate. Specific examples of such commercially available products include A-DOD-N, A-HD-N, A-NOD-N, APG-100, APG-200, APG-400, A-GLY-9E, A-GLY-20E, A-TMM-3, A-TMPT, AD-TMP, ATM-35E, A-TMMT, A-9550, A-DPH, HD-N, NOD-N, NPG, TMPT (manufactured by Shin-Nakamura Chemical Co., Ltd.), and "ARONIX "M-220", "M-325", "M-240", "M-270", "M-309", "M-310", "M-321", "M-350", "M-360", "M-305", "M-306", "M-450", "M-451", "M-408" , "M-400", "M-402", "M-403", "M-404", "M-" Examples include 405", M-406 (manufactured by Toa Gosei Co., Ltd.), EBECRYL11, 145, 150, 40, 140, 180, DPGDA, HDDA, TPGDA, HPNDA, PETIA, PETRA, TMPTA, TMPEOTA, DPHA, and the EBECRYL series (manufactured by Daicel-Cytec Co., Ltd.).

The content of the crosslinking agent is preferably 1 to 30 parts by mass, and more preferably 3 to 20 parts by mass, relative to 100 parts by mass of the total amount of the polymerizable liquid crystal compound. If the content of the crosslinking agent is below the lower limit, problems are likely to occur during processing such as polishing, and if it is above the upper limit, the orientation state of the liquid crystal compound becomes unstable, making it more likely that orientation defects will occur.

The reactive additive that may be contained in the composition containing the polymerizable liquid crystal compound is preferably one having a carbon-carbon unsaturated bond and an active hydrogen reactive group in its molecule. The "active hydrogen reactive group" here means a group that is reactive to a group having active hydrogen such as a carboxyl group (-COOH), a hydroxyl group (-OH), or an amino group (-NH ₂ ), and representative examples thereof include a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, a thioisocyanate group, and a maleic anhydride group. The number of carbon-carbon unsaturated bonds and active hydrogen reactive groups that the reactive additive has in its molecule is usually 1 to 20, and preferably 1 to 10.

In the reactive additive, it is preferable that at least two active hydrogen reactive groups are present in the molecule. In this case, the multiple active hydrogen reactive groups may be the same or different.

The carbon-carbon unsaturated bond that the reactive additive has in the molecule refers to a carbon-carbon double bond or a carbon-carbon triple bond, and is preferably a carbon-carbon double bond. In particular, the reactive additive preferably contains a carbon-carbon unsaturated bond in the molecule as a vinyl group and/or a (meth)acrylic group. Furthermore, it is preferable that the active hydrogen reactive group is at least one selected from the group consisting of an epoxy group, a glycidyl group, and an isocyanate group. In particular, a reactive additive having an acrylic group as the carbon-carbon double bond and an isocyanate group as the active hydrogen reactive group is particularly preferable.

Examples of reactive additives include compounds having a (meth)acrylic group and an epoxy group, such as methacryloxyglycidyl ether and acryloxyglycidyl ether; compounds having a (meth)acrylic group and an oxetane group, such as oxetane acrylate and oxetane methacrylate; compounds having a (meth)acrylic group and a lactone group, such as lactone acrylate and lactone methacrylate; compounds having a vinyl group and an oxazoline group, such as vinyl oxazoline and isopropenyl oxazoline; compounds having a (meth)acrylic group and an isocyanate group, such as isocyanatomethyl acrylate, isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate, and oligomers of these monomers. In addition, compounds having a vinyl group or vinylene group and an acid anhydride, such as methacrylic anhydride, acrylic anhydride, maleic anhydride, and vinyl maleic anhydride, can be mentioned. Among these, methacryloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyloxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, or oligomers of these monomers are preferred, and isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate, or oligomers of these monomers are particularly preferred.

When the polymerizable liquid crystal composition contains a reactive additive, the content is usually 0.1 parts by mass or more and 30 parts by mass or less, and preferably 0.1 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the polymerizable liquid crystal compound.

The composition containing the polymerizable liquid crystal compound may contain a leveling agent to make the coating film obtained by applying the composition flatter. Examples of the leveling agent include silicone-based, polyacrylate-based, and perfluoroalkyl-based leveling agents.

The content of the leveling agent is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, it is easy to align the polymerizable liquid crystal compound, and the obtained liquid crystal cured film (cured layer of the polymerizable liquid crystal compound) tends to be smoother, which is preferable.

The liquid crystal layer forming composition can be applied by known methods such as coating methods such as spin coating, extrusion, gravure coating, die coating, slit coating, bar coating, and applicator methods, and printing methods such as flexography. After applying the liquid crystal layer forming composition, it is preferable to remove the solvent under conditions that do not polymerize the polymerizable liquid crystal compound contained in the applied layer. Examples of drying methods include natural drying, ventilation drying, heat drying, and reduced pressure drying.

The polymerization of the polymerizable liquid crystal compound after drying of the coating layer can be carried out by a known method of polymerizing a compound having a polymerizable functional group. Examples of the polymerization method include thermal polymerization and photopolymerization, and photopolymerization is preferable from the viewpoint of ease of polymerization. When polymerizing the polymerizable liquid crystal compound by photopolymerization, it is preferable to use a liquid crystal layer forming composition containing a photopolymerization initiator, apply and dry this liquid crystal layer forming composition, align the polymerizable liquid crystal compound contained in the dried coating after drying, and perform photopolymerization while maintaining this liquid crystal alignment state.

Photopolymerization can be carried out by irradiating the polymerizable liquid crystal compound in the dried film with active energy rays. The active energy rays to be irradiated can be appropriately selected depending on the type and amount of polymerizable groups in the polymerizable liquid crystal compound, the type of photopolymerization initiator, etc., and can include, for example, one or more active energy rays selected from the group consisting of visible light, ultraviolet light, laser light, X-rays, α-rays, β-rays, and γ-rays. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and photopolymerization devices that are widely used in this field can be used. It is preferable to select the type of polymerizable liquid crystal compound and photopolymerization initiator so that they can be photopolymerized by ultraviolet light. In photopolymerization, the polymerization temperature can also be controlled by irradiating the active energy rays while cooling the dried film with an appropriate cooling means.

When the coating layer of the liquid crystal layer forming composition is cured by ultraviolet irradiation, the light irradiation intensity of the ultraviolet light is not particularly limited, but is preferably 10 to 1,000 mW/cm ² , and more preferably 100 to 600 mW/cm ^2. If the light irradiation intensity to the coating layer is less than 10 mW/cm ² , the reaction time becomes too long, and if it exceeds 1,000 mW/cm ² , the heat radiated from the light source may cause wrinkles in the base layer, resulting in uneven retardation. The irradiation intensity is an intensity in a wavelength region effective for activating a polymerization initiator, preferably a photoradical polymerization initiator, more preferably an intensity in a wavelength region of 400 nm or less, and even more preferably an intensity in a wavelength region of 280 to 320 nm. It is preferable to set the cumulative light amount to be 10 mJ/ ^cm2 or more, preferably 100 to 1,000 mJ/ ^cm2 , more preferably 400 to 1,000 mJ/ ^cm2 , even more preferably 600 to 1,000 mJ/ ^cm2 , and particularly preferably 600 to 1,000 mJ/ ^cm2 , by irradiating the coating layer with such light irradiation intensity once or multiple times. If the cumulative light amount to the coating layer is less than 10 mJ/ ^cm2 , the generation of active species derived from the polymerization initiator is insufficient, and the coating layer is insufficiently cured. If the cumulative light amount exceeds 1,000 mJ/ ^cm2 , the irradiation time becomes very long, which is disadvantageous for improving productivity. The wavelength of light (UVA (320 to 390 nm), UVB (280 to 320 nm), etc.) during light irradiation varies depending on the thickness and type of the base layer, the types of components contained in the composition for forming a liquid crystal layer, and the combination of components in the composition for forming a liquid crystal layer, and the like, and the integrated amount of light required also changes depending on the wavelength during light irradiation.

When the coating layer of the liquid crystal layer forming composition is cured by UV irradiation, the temperature during UV irradiation is preferably 25°C or higher, more preferably 50°C or higher, and even more preferably 80°C or higher, from the viewpoint of sufficiently increasing the degree of polymerization. Furthermore, if the temperature is too high, wrinkles may occur in the base layer, and there is a concern that unevenness in retardation may occur. Therefore, the temperature during UV irradiation is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 120°C or lower. The above upper and lower limit values can be combined in any combination.

(First base layer, second base layer)
The first substrate layer and the second substrate layer (hereinafter, both may be collectively referred to as "substrate layers") support an alignment layer and a liquid crystal layer, which will be described later, formed on these substrate layers. The base layer preferably is a film made of a resin material.

As the resin material, for example, a resin material excellent in transparency, mechanical strength, thermal stability, stretchability, etc. is used. Specifically, polyolefin resins such as polyethylene and polypropylene; cyclic polyolefin resins such as norbornene-based polymers; polyester resins such as PET and polyethylene naphthalate; (meth)acrylic acid resins such as poly(methyl meth)acrylate; cellulose ester resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; vinyl alcohol resins such as polyvinyl alcohol and polyvinyl acetate; polycarbonate resins; polystyrene resins; polyarylate resins; polysulfone resins; polyethersulfone resins; polyamide resins; polyimide resins; polyether ketone resins; polyphenylene sulfide resins; polyphenylene oxide resins, and mixtures and copolymers thereof can be mentioned. Of these resins, it is preferable to use any one of cyclic polyolefin resins, polyester resins, cellulose ester resins, and (meth)acrylic acid resins, or mixtures thereof.

The thickness of the base layer is not particularly limited, but in general, from the standpoint of strength, ease of handling, and other workability, it is preferably 1 to 300 μm, more preferably 10 to 200 μm, and even more preferably 30 to 120 μm.

When the first retardation layer with a substrate layer has a first alignment layer, or when the second retardation layer with a substrate layer has a second alignment layer, in order to improve the adhesion between the first substrate layer and the first alignment layer, and between the second substrate layer and the second alignment layer, at least the surface of the first substrate layer on which the first alignment layer is formed and at least the surface of the second substrate layer on which the second alignment layer is formed may be subjected to corona treatment, plasma treatment, flame treatment, or the like, or a primer layer, or the like may be formed.

The substrate layer is peelable from the liquid crystal layer or the alignment layer, and the magnitude of the peeling force between the substrate layer and the liquid crystal layer or the alignment layer must be determined taking into account the order in which the substrate layers are peeled off. It is preferable that the peeling force of the first substrate layer, which is separated first from the retardation laminate, is smaller than the peeling force of the second substrate layer, which is separated later.

(First lamination layer, second lamination layer, third lamination layer)
The first attachment layer, the second attachment layer, and the third attachment layer (hereinafter, these may be collectively referred to as "attachment layers") may be pressure-sensitive adhesive layers or adhesive curing layers. The pressure-sensitive adhesive layer can be formed using a pressure-sensitive adhesive composition, and the cured adhesive layer can be formed using an adhesive composition.

(Adhesive Layer)
The adhesive layer refers to a layer composed of an adhesive composition. In this specification, the "adhesive" is a so-called pressure-sensitive adhesive that exhibits adhesiveness by attaching itself to an adherend such as a polarizing plate or a liquid crystal layer. In addition, the active energy ray curable adhesive described later can adjust the crosslinking degree and adhesive strength by irradiating with energy rays.

As the adhesive, any adhesive known in the art that has excellent optical transparency can be used without any particular restrictions. For example, an adhesive having a base polymer such as an acrylic, urethane, silicone, or polyvinyl ether adhesive can be used. In addition, an active energy ray curable adhesive, a heat curable adhesive, or the like may be used. Among these, an adhesive having an acrylic resin as a base polymer that has excellent transparency, adhesive strength, removability (hereinafter also referred to as reworkability), weather resistance, heat resistance, and the like is preferable. The adhesive layer is preferably composed of a reaction product of an adhesive composition containing a (meth)acrylic resin, a crosslinking agent, and a silane compound, and may contain other components.

The adhesive layer may be formed using an active energy ray curable adhesive. The active energy ray curable adhesive is prepared by blending an ultraviolet-curable compound such as a multifunctional acrylate into an adhesive composition, forming an adhesive layer, and then curing the adhesive layer by irradiating it with ultraviolet light, thereby forming a harder adhesive layer. The active energy ray curable adhesive has the property of being cured by irradiation with energy rays such as ultraviolet rays and electron beams. The active energy ray curable adhesive has adhesiveness even before irradiation with energy rays, and therefore is an adhesive that has the property of adhering to an adherend such as an optical film or a retardation layer, and being cured by irradiation with energy rays to adjust the adhesion.

Active energy ray-curable adhesives generally contain an acrylic adhesive and an energy ray-polymerizable compound as the main components. Usually, a crosslinking agent is also blended, and if necessary, a photopolymerization initiator, photosensitizer, etc. can also be blended.

The thickness of the adhesive layer is preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the adhesive layer is preferably 40 μm or less, and more preferably 30 μm or less. The above upper and lower limit values can be combined in any combination.

(cured adhesive layer)
The adhesive cured layer refers to an adhesive cured layer formed by curing a curable component in an adhesive composition. The adhesive composition for forming the adhesive cured layer is an adhesive other than a pressure-sensitive adhesive (adhesive), and examples thereof include water-based adhesives and active energy ray curable adhesives. Examples of water-based adhesives include adhesives in which a polyvinyl alcohol resin is dissolved or dispersed in water. Examples of active energy ray curable adhesives include solvent-free active energy ray curable adhesives containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays. By using a solvent-free active energy ray curable adhesive, the adhesion between layers can be improved. On the other hand, if the active energy ray curable adhesive contains a solvent (especially an organic solvent), sufficient adhesion cannot be obtained even if the curable component contained in the adhesive is the same, and when the retardation laminate or the optical laminate is cut to a predetermined size, problems such as peeling at the end of the adhesive tend to occur. In addition, since a process of drying the solvent is added, additional shrinkage stress due to heat is applied, and curling may easily occur in the retardation laminate or the optical laminate.

The active energy ray curable adhesive preferably contains either one or both of a cationic polymerizable curable compound and a radical polymerizable curable compound, since these exhibit good adhesive properties. The active energy ray curable adhesive may further contain a cationic polymerization initiator or a radical polymerization initiator for initiating the curing reaction of the curable compound.

Examples of cationic polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (compounds having one or more oxetane rings in the molecule), and combinations of these.

Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having radically polymerizable double bonds, or combinations of these.

The active energy ray-curable adhesive may contain a sensitizer as necessary. The use of a sensitizer improves reactivity, and can further improve the mechanical strength and adhesive strength of the cured adhesive layer. Any known sensitizer can be used as appropriate. When a sensitizer is added, the amount of the sensitizer added is preferably in the range of 0.1 to 20 parts by mass per 100 parts by mass of the total amount of the active energy ray-curable adhesive.

The active energy ray-curable adhesive may contain additives such as ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow control agents, plasticizers, defoamers, antistatic agents, leveling agents, and solvents, as necessary.

The adhesive composition layer may be formed by applying the adhesive composition to the bonding surface of the first retardation layer with the base layer or the second retardation layer with the base layer. As the application method, a conventional coating technique using a die coater, a comma coater, a reverse roll coater, a gravure coater, a rod coater, a wire bar coater, a doctor blade coater, an air doctor coater, or the like may be adopted.

There are no particular limitations on the drying method when using a water-based adhesive, but for example, a drying method using a hot air dryer or an infrared dryer can be used.

When an active energy ray-curable adhesive is used, the adhesive composition layer can be cured by irradiating it with active energy rays such as ultraviolet rays, visible light, electron beams, or X-rays to form a cured adhesive layer. As the active energy ray, ultraviolet rays are preferred, and in this case, the light source that can be used may be a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a metal halide lamp, or the like.

The thickness of the adhesive cured layer is, for example, 0.01 μm or more, may be 0.05 μm or more, may be 0.5 μm or more, and is usually 5 μm or less, may be 3 μm or less, or may be 2 μm or less.

(Linear Polarizing Layer)
The linearly polarizing layer has a property of transmitting linearly polarized light having a vibration plane perpendicular to the absorption axis when unpolarized light is incident on the linearly polarizing layer. The linearly polarizing layer may include a polyvinyl alcohol (hereinafter, sometimes abbreviated as "PVA")-based resin film, or may be a cured film obtained by aligning a dichroic dye in a polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound.

Examples of linearly polarizing layers containing a PVA-based resin film include hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer films, which have been dyed with iodine or a dichroic substance such as a dichroic dye, and stretched. Because of their excellent optical properties, it is preferable to use a linearly polarizing layer obtained by dyeing a PVA-based resin film with iodine and stretching it uniaxially.

PVA-based resins can be produced by saponifying polyvinyl acetate-based resins. Polyvinyl acetate-based resins can be polyvinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and other monomers that can be copolymerized with vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides with ammonium groups.

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

A film made from such a PVA-based resin is used as the original film for the linear polarizing layer. The method for making the PVA-based resin film is not particularly limited, and the film can be made by a known method. The thickness of the PVA-based resin original film is, for example, about 10 to 100 μm, preferably about 10 to 60 μm, and more preferably about 15 to 30 μm.

Other examples of the manufacturing method of the linear polarizing layer including a PVA-based resin film include a process that includes the steps of first preparing a substrate film, applying a solution of a resin such as a PVA-based resin onto the substrate film, and then drying to remove the solvent to form a resin layer on the substrate film. A primer layer can be formed in advance on the surface of the substrate film on which the resin layer is to be formed. A resin film such as PET can be used as the substrate film. Examples of materials for the primer layer include PVA resin crosslinked with the hydrophilic resin used in the linear polarizing layer.

Next, the amount of solvent such as water in the resin layer is adjusted as necessary, and then the base film and the PVA resin layer are uniaxially stretched. The PVA resin layer is then dyed with a dichroic dye such as iodine to adsorb and align the dichroic dye in the PVA resin layer. Next, as necessary, the PVA resin layer with the dichroic dye adsorbed and aligning is treated with an aqueous boric acid solution, and a washing step is performed to wash off the aqueous boric acid solution. This produces a PVA resin layer with the dichroic dye adsorbed and aligning, i.e., a film of a linearly polarizing layer. Publicly known methods can be used for each step.

The uniaxial stretching of the substrate film and the PVA resin layer may be performed before dyeing, during dyeing, or during the boric acid treatment after dyeing. The uniaxial stretching may be performed at each of these multiple stages. The substrate film and the PVA resin layer may be uniaxially stretched in the MD direction (film conveying direction). In this case, they may be uniaxially stretched between rolls with different peripheral speeds, or may be uniaxially stretched using a heated roll. The substrate film and the PVA resin layer may be uniaxially stretched in the TD direction (direction perpendicular to the film conveying direction). In this case, the so-called tenter method can be used. The substrate film and the PVA resin layer may be stretched by dry stretching in the air, or by wet stretching in a state in which the PVA resin layer is swollen with a solvent. In order to express the performance of the linearly polarizing layer, the stretching ratio is 4 times or more, preferably 5 times or more, and particularly preferably 5.5 times or more. There is no particular upper limit to the stretching ratio, but from the viewpoint of suppressing breakage, it is preferably 8 times or less.

The linearly polarizing layer produced by the above method can be obtained by laminating a protective layer (described below) and then peeling off the substrate film. This method makes it possible to further reduce the thickness of the linearly polarizing layer.

As a method for producing a linearly polarizing layer, which is a cured film obtained by orienting a dichroic dye in a polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound, there can be mentioned a method in which a composition for forming a polarizing layer containing a polymerizable liquid crystal compound and a dichroic dye is applied onto a substrate film, and the polymerizable liquid crystal compound is polymerized and cured while maintaining the liquid crystal state to form a linearly polarizing layer. The linearly polarizing layer thus obtained is in a state in which it is laminated onto the substrate film, and the linearly polarizing layer with the substrate film may be used as a polarizing plate, which will be described later.

As the dichroic dye, a dye having different absorbance in the long axis direction and absorbance in the short axis direction of the molecule can be used, and for example, a dye having a maximum absorption wavelength (λmax) in the range of 300 to 700 nm is preferable. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, anthraquinone dyes, etc., and among these, azo dyes are preferable. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, stilbene azo dyes, etc., and bisazo dyes and trisazo dyes are more preferable.

The composition for forming the polarizing layer may contain a solvent, a polymerization initiator such as a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, and the like. The polymerizable liquid crystal compound, dichroic dye, solvent, polymerization initiator, photosensitizer, polymerization inhibitor, and the like contained in the composition for forming the polarizing layer may be a known compound, and may be, for example, one exemplified in JP-A-2017-102479 or JP-A-2017-83843. The polymerizable liquid crystal compound may be the same as the compound exemplified as the polymerizable liquid crystal compound used to obtain the liquid crystal layer (first liquid crystal layer, second liquid crystal layer) described later. The method for forming a linear polarizing layer using the composition for forming the polarizing layer may also be the method exemplified in the above publication.

The thickness of the linearly polarizing layer is preferably 2 μm or more, and more preferably 3 μm or more. The thickness of the linearly polarizing layer is 25 μm or less, preferably 15 μm or less, more preferably 13 μm or less, and even more preferably 7 μm or less. The above upper and lower limit values can be combined in any combination.

(Polarizer)
A polarizing plate can be formed by laminating a protective layer on one or both sides of the linearly polarizing layer via a known adhesive layer or adhesive cured layer. This polarizing plate is a so-called linear polarizing plate. As the protective layer that can be laminated on one or both sides of the linearly polarizing layer, for example, a film formed from a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, stretchability, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose; polyester resins such as PET and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamide; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having cyclo- and norbornene structures (also called norbornene-based resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, and mixtures thereof. When protective layers are laminated on both sides of the linearly polarizing layer, the resin compositions of the two protective layers may be the same or different.

The film formed from the thermoplastic resin may be subjected to a surface treatment (e.g., corona treatment, etc.) to improve adhesion with the linear polarizing layer made of the PVA-based resin and the dichroic material, and a thin layer such as a primer layer (also called an undercoat layer) may be formed.

The protective layer may be, for example, the above-mentioned thermoplastic resin that has been stretched, or may not be stretched (hereinafter, sometimes referred to as "unstretched resin"). Examples of stretching treatments include uniaxial stretching and biaxial stretching.

The thickness of the protective layer is preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the protective layer is preferably 50 μm or less, and more preferably 30 μm or less. The above upper and lower limit values can be combined in any combination.

The surface of the protective layer opposite the linear polarizing layer may have a surface treatment layer, such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, an anti-glare layer, a diffusion layer, etc. The surface treatment layer may be a separate layer laminated on the protective layer, or may be formed by applying a surface treatment to the surface of the protective layer.

The thickness of the polarizing plate is not particularly limited, but is usually 2 μm or more and 300 μm or less. The thickness of the polarizing plate may be 10 μm or more, 150 μm or less, 120 μm or less, or 80 μm or less.

(Polarizing plate with protective film)
A polarizing plate can be made into a polarizing plate with a protective film by laminating a protective film on one side of the polarizing plate. The protective film may be a resin film for the protective film on which an adhesive layer is formed, or may be formed of a self-adhesive film. The thickness of the protective film may be, for example, 30 to 200 μm, preferably 40 to 150 μm, and more preferably 50 to 120 μm.

Examples of resins constituting the resin film for the protective film include polyolefin resins such as polyethylene resins and polypropylene resins; cyclic polyolefin resins; polyester resins such as PET and polyethylene naphthalate; polycarbonate resins; (meth)acrylic resins, etc. Among these, polyester resins such as PET are preferred. The resin film for the protective film may have a single-layer structure, but may also have a multi-layer structure of two or more layers.

The adhesive constituting the adhesive layer for the protective film may be the same as the adhesive constituting the adhesive layer described above. The protective film can be obtained by forming an adhesive layer by applying an adhesive composition to the surface of the resin film for the protective film and drying it. If necessary, the adhesive-coated surface of the resin film for the protective film may be subjected to a surface treatment (e.g., corona treatment, etc.) to improve adhesion, and a thin layer such as a primer layer (also called an undercoat layer) may be formed. If necessary, the adhesive layer for the protective film may have a release film for covering and protecting the surface opposite to the resin film for the protective film. This release film can be peeled off at an appropriate timing when laminating with a polarizing plate.

A self-adhesive film is a film that can adhere by itself without the need for a means for adhesion such as an adhesive layer, and can maintain that adhered state. Self-adhesive films can be formed, for example, using polypropylene-based resins and polyethylene-based resins.

The thickness of the polarizing plate with the protective film is preferably 32 μm or more and 500 μm or less. The thickness of the polarizing plate with the protective film may be 40 μm or more, and may be 350 μm or less, 200 μm or less, or 150 μm or less.

(Release film)
The release film covers and protects the adhesive layer or supports the adhesive layer, and functions as a separator that can be peeled off from the adhesive layer. Examples of the release film include a film in which a release treatment such as silicone treatment has been applied to the surface of the adhesive layer side of the substrate film. Examples of the resin material constituting the substrate film include the same resin material as the above-mentioned resin material constituting the protective layer. The resin film may have a single layer structure, or may be a multilayer resin film having a multilayer structure of two or more layers.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples and comparative examples, "%" and "parts" are by mass % and parts by mass unless otherwise specified.

[Measurement of puncture elastic modulus E1, E2]
(Preparation of measurement sample)
The first retardation layer with the substrate layer and the second retardation layer with the substrate layer used in the examples and comparative examples were cut into a size of 40 mm x 40 mm, and each was used as a cut-out piece. A glued mount of 40 mm x 40 mm was also prepared. The glued mount was cut out in a square of 30 mm x 30 mm in the center. The cut-out piece was attached to the glued mount so that the surface of the first retardation layer or the surface of the second retardation layer of the cut-out piece was in contact with the glue on the glued mount. Next, the first substrate layer or the second substrate layer was separated from the cut-out piece to prepare a measurement sample for the puncture elastic modulus E1 and E2.

(Determination of puncture elastic moduli E1 and E2)
A needle with a tip diameter of 1 mmφ and 0.5R was attached to a handy compression tester ("NDG5 piercing tester needle penetration force measurement specification", manufactured by Kato Tech Co., Ltd.). The needle was pierced vertically from the first retardation layer side or the second retardation layer side (opposite the glued mount side) of the measurement sample at a piercing speed of 0.33 cm/sec into the first retardation surface or the second retardation surface of the measurement sample. The strain amount S [mm] at the stress F [g f ] just before the measurement sample breaks due to this piercing was calculated, and the value of stress F [g f ] / strain amount S [mm] was calculated. This operation was performed on each of the five measurement samples, and the average value was determined as the piercing elastic modulus E1, E2 [g f /mm]. The measurement was performed in an environment of a temperature of 23 ° C. and a relative humidity of 50%.

[Calculation of curl amount]
(Preparation of COP film with adhesive layer)
A cyclic polyolefin film with a protective film (thickness 23 μm, ZF-14, manufactured by Zeon Corporation) (hereinafter sometimes referred to as "COP with protective film") was prepared with a size of 380 mm in MD (film conveying direction) length x 180 mm in TD (direction perpendicular to the film conveying direction). A corona treatment (800 W, 10 m/min, bar width 700 mm, 1 pass) was applied to the surface opposite to the protective film side of the COP with protective film. In addition, the first separator was peeled off from the adhesive layer with double-sided separator (380 mm x 180 mm) described later. Using an automatic laminating machine HALTEC, the COP surface of the COP with protective film prepared above and the surface exposed by peeling the first separator from the adhesive layer with double-sided separator were bonded to obtain a COP film with an adhesive layer. The COP film with a pressure-sensitive adhesive layer had a COP with a protective film (protective film, cyclic polyolefin film), a pressure-sensitive adhesive layer, and a second separator in this order.

(Measurement of curl value of retardation laminate with COP film (test piece (a)))
The second separator was peeled off from the COP film with the adhesive layer, and the surface of the exposed adhesive layer was bonded to the surface of the retardation laminate obtained in the examples and comparative examples by peeling off the first base layer. As a result, a laminate was obtained in which the COP with the protective film, the adhesive layer, the first retardation layer, the bonding layer, the second retardation layer, and the second base layer were laminated in this order, and this laminate was kept for 24 hours under an environment of a temperature of 23 ° C. and a relative humidity of 55%. The above laminate was cut out so that the long side length was 150 mm, the short side length was 50 mm, and the angle between the long side and the TD direction of the above laminate was 45 degrees. The protective film of the COP with the protective film was peeled off from the cut piece, and the second base layer was separated, which was used as the test piece (a).

After sufficiently discharging the test piece (a), the concave surface of the test piece (a) was placed on a reference surface (horizontal table), and the heights of the two corners on the diagonal line of the test piece (a) whose extension direction is relatively close to the direction parallel to the MD direction of the laminate were measured from the reference surface, and the average value was used as the measured MD curl value. Similarly, the heights of the two corners on the diagonal line whose extension direction is relatively close to the direction parallel to the TD direction were measured from the reference surface, and the average value was used as the measured TD curl value. When the test piece (a) was placed on the reference surface so that the cyclic polyolefin film (hereinafter sometimes referred to as "COP film") side exposed by peeling off the protective film was on top, if the two corners of the test piece (b) rose up, this curl was considered to be a positive curl, and the height of the corners from the reference surface was expressed as a positive value. On the other hand, when test piece (a) is placed on a reference surface with the COP film side facing down, if the above two corners of test piece (a) rise up, this curl is considered to be reverse curl, and the height of the corners from the reference surface is expressed as a negative value.

(Measurement of curl value of COP film with adhesive layer (test piece (b)))
A test piece (b) was obtained in the same manner as in the measurement of the curl value of the retardation laminate, except that the protective film and the second separator of the COP with protective film were peeled off from the COP film with the adhesive layer prepared above, and the measured MD curl value and the measured TD curl value were determined. In this embodiment, the measured MD curl value and the measured TD curl value of the test piece (b) were both 0 mm.

(Determination of Curl Value of Retardation Laminate)
The measured MD curl value obtained for the test piece (b) was subtracted from the measured MD curl value obtained for the test piece (a) to obtain the MD curl value of the retardation laminate.Similarly, the measured TD curl value obtained for the test piece (b) was subtracted from the measured TD curl value obtained for the test piece (a) to obtain the TD curl value of the retardation laminate.The MD curl value and the TD curl value indicate that curl is suppressed if they are close to 0, and the larger the absolute value, the more curling progresses.

[Preparation of adhesive layer with double-sided separator]
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube was charged with 97.0 parts of n-butyl acrylate, 1.0 parts of acrylic acid, 0.5 parts of 2-hydroxyethyl acrylate, 200 parts of ethyl acetate, and 0.08 parts of 2,2'-azobisisobutyronitrile, and the air in the reaction vessel was replaced with nitrogen gas. The reaction solution was heated to 60°C while stirring under a nitrogen atmosphere, reacted for 6 hours, and then cooled to room temperature. When the weight average molecular weight of a portion of the obtained solution was measured, the production of a (meth)acrylic acid ester polymer of 1.8 million was confirmed.

100 parts of the (meth)acrylic acid ester polymer obtained above (solid content equivalent; the same applies below) was mixed with 0.30 parts of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") as an isocyanate-based crosslinking agent, and 0.30 parts of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM403") as a silane coupling agent, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of the adhesive composition.

The above coating solution was applied to the release-treated surface (peeling surface) of a first separator (SP-PLR382190, manufactured by Lintec Corporation) with an applicator so that the thickness after drying would be 25 μm, and then dried at 100°C for 1 minute to form an adhesive layer. Another second separator (SP-PLR381031, manufactured by Lintec Corporation) was attached to the surface of the adhesive layer opposite to the surface to which the separator was attached, to obtain an adhesive layer with a double-sided separator.

[Preparation of adhesive composition]
The cationic curable components a1 to a3 shown in [a] to [c] below, and the cationic polymerization initiators and sensitizers shown in [d] and [e] below were mixed and then degassed to prepare a photocurable adhesive composition. The parts shown below are the amounts of each material in the adhesive composition.
[a] Cationic curable component a1
3',4'-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate (product name: CEL2021P, manufactured by Daicel Corporation): 70 parts (solid content)
[b] Cationic curable component a2
Neopentyl glycol diglycidyl ether (product name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts (solid content)
[c] Cationic curable component a3
2-Ethylhexyl glycidyl ether (product name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts (solid content)
[d] Cationic polymerization initiator: 50% propylene carbonate solution of "CPI-100" (manufactured by San-Apro Co., Ltd.): 2.25 parts (solid content)
[e] Sensitizer 1,4-diethoxynaphthalene: 2 parts (solid content)

・溶剤（シクロペンタノン）：９５部 [Preparation of first retardation layer with base layer]
(Preparation of photoalignment layer forming composition (1))
The following components were mixed, and the resulting mixture was stirred at a temperature of 80° C. for 1 hour to obtain a composition for forming a photoalignment layer (1).
Photoalignment material (compound represented by the following formula): 5 parts

Solvent (cyclopentanone): 95 parts

・重合性液晶化合物Ａ２（下記式で表される化合物）：２０部

・重合開始剤（２－ジメチルアミノ－２－ベンジル－１－（４－モルホリノフェニル）ブタン－１－オン（イルガキュア３６９；チバスペシャルティケミカルズ社製））：６部
・溶剤（シクロペンタノン）：４００部 (Preparation of Liquid Crystal Layer Forming Composition (A-1))
The following components were mixed, and the mixture was stirred at 80° C. for 1 hour to obtain a liquid crystal layer forming composition (A-1). Polymerizable liquid crystal compound A1 and polymerizable liquid crystal compound A2 were synthesized by the method described in JP-A-2010-31223.
Polymerizable liquid crystal compound A1 (compound represented by the following formula): 80 parts

Polymerizable liquid crystal compound A2 (compound represented by the following formula): 20 parts

Polymerization initiator (2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals)): 6 parts Solvent (cyclopentanone): 400 parts

(Preparation of the first retardation layer with the base layer)
A polyethylene terephthalate (PET) film (first substrate layer) having a thickness of 100 μm was treated once using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) under the conditions of an output of 0.3 kW and a treatment speed of 3 m/min. The photo-alignment layer forming composition (1) was applied to the corona-treated surface using a bar coater, dried at 80° C. for 1 minute, and exposed to polarized UV light with an integrated light amount of 100 mJ/cm ² using a polarized UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) to obtain a photo-alignment layer (first alignment layer). The thickness of the obtained photo-alignment layer was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) and was 100 nm.

Next, the liquid crystal layer forming composition (A-1) was applied onto the photo-alignment layer using a bar coater, and dried at 120°C for 1 minute. Then, a high pressure mercury lamp (Unicur VB-15201BY-A, manufactured by Ushio Inc.) was used to irradiate with ultraviolet light (under nitrogen atmosphere, wavelength: 365 nm, irradiation intensity at wavelength 365 nm: 10 mW/cm ² , accumulated light quantity: 2000 mJ/cm ² ) to form a first liquid crystal layer, thereby obtaining a first retardation layer with a substrate layer. The thickness of the obtained first liquid crystal layer was measured with a laser microscope (LEXT, manufactured by Olympus Corporation), and the thickness was 2.0 μm. When the PET film (first substrate layer) was separated from the first retardation layer with the substrate layer, the peeling interface was between the photoalignment layer and the first liquid crystal layer, the thickness of the first retardation layer (first liquid crystal layer) was 2.0 μm, and the puncture elastic modulus E1 of the first retardation layer was 39.9 g f /mm.

[Preparation of second retardation layer (1) with base layer]
(Preparation of Orientation Layer-Forming Composition (2))
2-Butoxyethanol was added to Sunever SE-610 (manufactured by Nissan Chemical Industries, Ltd.), a commercially available oriented polymer, to obtain an orientation layer forming composition (2). The obtained orientation layer forming composition (2) had a solid content of 1% relative to the total amount of the composition, and a solvent content of 99% relative to the total amount of the composition. The solid content of Sunever SE-610 was calculated from the concentration stated in the delivery specifications.

・重合開始剤（イルガキュア（登録商標）９０７、ＢＡＳＦジャパン社製）：０．５％：
・反応添加剤（Ｌａｒｏｍｅｒ（登録商標）ＬＲ－９０００、ＢＡＳＦジャパン社製）：１．１％
・溶剤（プロピレングリコール１－モノメチルエーテル２－アセタート）：７９．１％ (Preparation of Liquid Crystal Layer Forming Composition (B-1))
The following components were mixed, and the resulting mixture was stirred at 80° C. for 1 hour and then cooled to room temperature to obtain a liquid crystal layer forming composition (B-1).
Polymerizable liquid crystal compound (LC242, manufactured by BASF): 19.2%

Polymerization initiator (Irgacure (registered trademark) 907, manufactured by BASF Japan Ltd.): 0.5%:
Reactive additive (Laromer (registered trademark) LR-9000, manufactured by BASF Japan): 1.1%
Solvent (propylene glycol 1-monomethyl ether 2-acetate): 79.1%

(Preparation of second retardation layer (1) with substrate layer)
A 38 μm thick polyethylene terephthalate (PET) film (second base layer) was treated once using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) under the conditions of an output of 0.3 kW and a treatment speed of 3 m/min. The surface subjected to the corona treatment was coated with the composition for forming an alignment layer (2) using a bar coater and dried at 90° C. for 1 minute to obtain an alignment layer (second alignment layer). The thickness of the obtained alignment layer was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) and found to be 2.2 μm.

Subsequently, the liquid crystal layer forming composition (B-1) was applied onto the alignment layer using a bar coater, and dried at 90 ° C. for 1 minute. Then, a high pressure mercury lamp (Uniquer VB-15201BY-A, manufactured by Ushio Inc.) was used to irradiate ultraviolet light (under a nitrogen atmosphere, wavelength: 365 nm, integrated light amount at wavelength 365 nm: 1000 mJ / cm ² ) to form a second liquid crystal layer, thereby obtaining a second retardation layer (1) with a substrate layer. The thickness of the second liquid crystal layer in the second retardation layer (1) with a substrate layer was 0.8 μm. The peeling interface when the PET film (second substrate layer) was separated from the second retardation layer (1) with a substrate layer was between the PET film and the alignment layer, the thickness of the second retardation layer (alignment layer and second liquid crystal layer) was 3.0 μm, and the puncture elastic modulus E2 of the second retardation layer was 36.0 g f / mm.

[Preparation of second retardation layer (2) with base layer]
(Preparation of Liquid Crystal Layer Forming Composition (B-2))
A liquid crystal layer forming composition (B-2) was prepared in the same manner as in the preparation of the liquid crystal layer forming composition (B-1), except that no reactive additive (Laromer (registered trademark) LR-9000) was contained.

(Preparation of second retardation layer (2) with substrate layer)
On the alignment layer, the liquid crystal layer forming composition (B-2) was applied instead of the liquid crystal layer forming composition (B-1), and the integrated light amount in the subsequent ultraviolet irradiation was set to 700 mJ / cm ^2. Except for this, the second retardation layer (2) with the substrate layer was obtained in the same procedure as in the preparation of the second retardation layer (1) with the substrate layer. The thickness of the second liquid crystal layer in the second retardation layer (2) with the substrate layer was 0.8 μm. The peeling interface when the PET film (second substrate layer) was separated from the second retardation layer (2) with the substrate layer was between the alignment layer and the second liquid crystal layer, the thickness of the second retardation layer (second liquid crystal layer) was 0.8 μm, and the puncture elastic modulus E2 of the second retardation layer was 8.2 g f / mm.

[Preparation of second retardation layer (3) with base layer]
Except for the fact that the cumulative amount of light in the ultraviolet irradiation after applying the liquid crystal layer forming composition (B-2) on the alignment layer was 1000 mJ / cm ² , the second retardation layer with the substrate layer (3) was obtained in the same procedure as in the preparation of the second retardation layer with the substrate layer (2). The thickness of the second liquid crystal layer in the second retardation layer with the substrate layer (3) was 0.8 μm. The peeling interface when the PET film (second substrate layer) was separated from the second retardation layer with the substrate layer (3) was between the alignment layer and the second liquid crystal layer, the thickness of the second retardation layer (second liquid crystal layer) was 0.8 μm, and the puncture elastic modulus E2 of the second retardation layer was 15.0 g f / mm.

[Preparation of second retardation layer (4) with base layer]
(Preparation of Liquid Crystal Layer Forming Composition (B-4))
A liquid crystal layer forming composition (B-4) was prepared in the same manner as in the preparation of the liquid crystal layer forming composition (B-1), except that the amount of the polymerization initiator (Irgacure (registered trademark) 907) was halved (0.25%).

(Preparation of second retardation layer (4) with substrate layer)
Except for using the liquid crystal layer forming composition (B-4), the second retardation layer with the substrate layer (4) was obtained in the same procedure as the preparation of the second retardation layer with the substrate layer (1). In the second retardation layer with the substrate layer (4), the thickness of the photo-alignment layer (second alignment layer) was 2.2 μm, and the thickness of the second liquid crystal layer was 0.8 μm. When the PET film (second substrate layer) was separated from the second retardation layer with the substrate layer (1), the peeling interface was between the PET film and the alignment layer, the thickness of the second retardation layer (alignment layer and second liquid crystal layer) was 3.0 μm, and the puncture modulus E2 of the second retardation layer was 23.0 g f / mm.

Example 1
The surface of the second retardation layer side of the second retardation layer (1) (MD length 380 mm × TD length 180 mm) with the substrate layer prepared above was treated once using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) under conditions of an output of 0.8 kW, a treatment speed of 10 m / min, and a bar width of 700 mm. The adhesive composition prepared above was applied to the corona-treated surface of the second retardation layer (1) with the substrate layer using a coater (bar coater manufactured by Daiichi Rika Co., Ltd.) so that the thickness after curing was 1 μm to form an adhesive composition layer.

The adhesive composition layer formed on the second retardation layer (1) with the substrate layer and the first retardation layer side of the first retardation layer with the substrate layer prepared above were laminated using an attachment device (LPA3301, manufactured by Fujipla Co., Ltd.). Thereafter, using a belt conveyor equipped ultraviolet irradiation device (the lamp is "H bulb" manufactured by Fusion UV Systems Co., Ltd.), the adhesive composition layer was cured by irradiating ultraviolet light so that the irradiation intensity in the UVA region was 390 mW / cm ² and the accumulated light amount was 420 mJ / cm ² , and the accumulated light amount in the UVB region was 400 mW / cm ² and 400 mJ / cm ² , to obtain a retardation laminate. The retardation laminate was a laminate in which the first substrate layer, the first retardation layer, the first bonding layer (adhesive cured layer), the second retardation layer, and the second substrate layer were laminated in this order. The curl value of the obtained retardation laminate was determined. The results are shown in Table 1.

[Comparative Examples 1 to 3]
A retardation laminate was obtained in the same manner as in Example 1, except that the second retardation layer with the base layer (2) to (4) was used instead of the second retardation layer with the base layer (1). The curl value of the obtained retardation laminate was determined. The results are shown in Table 1.

1, 1a, 1b, 1c retardation laminate, 5, 5a, 5b optical laminate, 10 first retardation layer, 11 first alignment layer, 12 first retardation layer, 15 first base layer, 18 group First retardation layer with material layer, 20 Second retardation layer, 21 Second alignment layer, 22 Second retardation layer, 25 Second base layer, 28 Second retardation layer with base material layer, 30 First Lamination layer, 32 Second lamination layer, 40 Optical film.

Claims (10)

An optical laminate having a retardation laminate, a second bonding layer, and an optical film in this order,
The retardation laminate includes a first retardation layer, a first attachment layer, and a second retardation layer in this order,
The first retardation layer includes a first liquid crystal layer which is a cured layer of a polymerizable liquid crystal compound,
The second retardation layer includes a second liquid crystal layer which is a cured layer of a polymerizable liquid crystal compound,
The puncture elastic modulus E1 of the first retardation layer is 35 gf/mm or more,
The puncture elastic modulus E1 and the puncture elastic modulus E2 of the second retardation layer satisfy the relationship of the following formula (1),
The thickness t1 of the first retardation layer and the thickness t2 of the second retardation layer satisfy the relationship of the following formula (2'),
An optical laminate, wherein the optical film is provided on the first retardation layer side of the retardation laminate via the second attachment layer.
0.7≦E1/E2≦1.3 (1)
0.1≦t1/t2≦0.8 (2') The optical laminate according to claim 1, wherein the puncture elastic modulus E2 is 55 gf/mm or less. the first retardation layer is a laminate of the first liquid crystal layer and a first alignment layer,
The optical laminate according to claim 1 , wherein the first alignment layer is provided on a side of the first liquid crystal layer opposite to a side of the first bonding layer. the second retardation layer is a laminate of the second liquid crystal layer and a second alignment layer,
The optical laminate according to claim 1 , wherein the second alignment layer is provided on a side of the second liquid crystal layer opposite to the first bonding layer. Further, a second base layer is provided on the opposite side of the second retardation layer to the first attachment layer,
The optical laminate according to any one of claims 1 to 4 , wherein the second base material layer is separably provided between the second base material layer and the second liquid crystal layer. The optical laminate according to any one of claims 1 to 5 , wherein the optical film comprises a polarizing plate having a linear polarizing layer and a protective layer provided on one or both sides of the linear polarizing layer. A method for producing an optical laminate including an optical film, a second attachment layer, a first retardation layer, a first attachment layer, and a second retardation layer in this order,
A step of preparing a retardation laminate including a first base layer, a first retardation layer, a first attachment layer, and a second retardation layer in this order;
Separating the first base layer from the retardation laminate;
and bonding the optical film to an exposed surface exposed by separating the first base layer via the second bonding layer,
The retardation laminate is
A step of preparing a base layer-attached first retardation layer having the first base material layer and the first retardation layer, and a base layer-attached second retardation layer having a second base material layer and the second retardation layer;
The first retardation layer side of the first retardation layer with the base layer and the second retardation layer side of the second retardation layer with the base layer are bonded together via the first bonding layer,
the first retardation layer includes a first liquid crystal layer formed by polymerizing a polymerizable liquid crystal compound on the first base layer,
the second retardation layer includes a second liquid crystal layer formed by polymerizing a polymerizable liquid crystal compound on the second base layer,
The puncture elastic modulus E1 of the first retardation layer is 35 gf/mm or more,
The puncture elastic modulus E1 and the puncture elastic modulus E2 of the second retardation layer satisfy the relationship of the following formula (1),
A method for producing an optical laminate , wherein a thickness t1 of the first retardation layer and a thickness t2 of the second retardation layer satisfy a relationship of the following formula (2') .
0.7≦E1/E2≦1.3 (1)
0.1≦t1/t2≦0.8 (2') The method for producing an optical laminate according to claim 7 , wherein the first retardation layer with a base layer has a first alignment layer between the first base layer and the first liquid crystal layer. The method for producing an optical laminate according to claim 7 or 8 , wherein the second retardation layer with a base layer has a second alignment layer between the second base layer and the second liquid crystal layer. The method for producing an optical laminate according to claim 7 , further comprising a step of separating the second base layer after the step of bonding via the second bonding layer.

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