WO2021131367A1

WO2021131367A1 - Method for manufacturing optical laminate

Info

Publication number: WO2021131367A1
Application number: PCT/JP2020/042027
Authority: WO
Inventors: 加藤　慎也; 光出▲崎▼
Original assignee: 住友化学株式会社
Priority date: 2019-12-23
Filing date: 2020-11-11
Publication date: 2021-07-01
Also published as: JP7406977B2; TW202126489A; JP2021099436A; CN114846371A; KR20220117920A

Abstract

[Problem] To provide a method for manufacturing an optical laminate which comprises: an optical film; and a retardation layer including a cured material layer formed of a polymerizable liquid crystal compound, and which is less likely to cause wrinkle defects even when curved with a small radius of curvature. [Solution] Provided is a method for manufacturing an optical laminate which comprises, in the following order, an optical film, a cured adhesive layer which is a cured material layer formed of an active energy ray-curable adhesive, and a retardation layer including a cured material layer formed of a polymerizable liquid crystal compound, the method comprising, in the following order: a step for laminating the optical film, the active energy ray-curable adhesive layer, and the retardation layer so that the active energy ray-curable adhesive layer is in contact with the retardation layer; a step for holding the laminate under conditions satisfying at least one among (1) holding at a temperature of at least 30ºC for at least 2 hours, (2) holding for at least 2 hours under vibration conditions, and (3) holding for at least 48 hours; and a step for curing the active energy ray-curable adhesive layer to form a cured adhesive layer.

Description

Manufacturing method of optical laminate

The present invention relates to a method for manufacturing an optical laminate, and also relates to an optical laminate.

In an image display device such as an organic EL display device, an optical laminate (elliptic polarizing plate) in which a polarizing element (linear polarizing element) and a retardation layer are combined is used for the purpose of preventing reflection of external light by a metal electrode. Sometimes. For example, in Japanese Patent Application Laid-Open No. 2018-017996 (Patent Document 1), a polarizing element and a retardation layer formed of a polymerizable liquid crystal compound are laminated via an ultraviolet curable adhesive layer, and the adhesive is irradiated with ultraviolet rays. It is described that the layer is cured to produce an elliptical polarizing plate.

JP-A-2018-017996

A conventional optical laminate produced by adhering an optical film containing a polarizer and a retardation layer formed of a polymerizable liquid crystal compound with an active energy ray-curable adhesive or an adhesive has a radius of curvature. When it is curved so as to be gradually reduced, fine wrinkles (hereinafter, also referred to as “wrinkle defects”) tend to occur in the retardation layer even at a stage having a relatively large radius of curvature. .. Considering application to a bendable or bendable image display device or the like, the optical laminate is required to be less likely to cause wrinkle defects even if it is bent with a small radius of curvature.

The present invention is an optical laminate including an optical film and a retardation layer including a cured product layer of a polymerizable liquid crystal compound, and an optical laminate in which wrinkle defects are unlikely to occur even when curved with a small radius of curvature, and a method for producing the same. Is to provide.

The present invention provides a method for producing an optical laminate and an optical laminate shown below.
[1] A method for manufacturing an optical laminate, which is a method for manufacturing an optical laminate.
The optical laminate includes an optical film, a cured adhesive layer which is a cured product layer of an active energy ray-curable adhesive, and a retardation layer including a cured product layer of a polymerizable liquid crystal compound in this order.
The manufacturing method is
A step of laminating the optical film, the active energy ray-curable adhesive layer, and the retardation layer so that the active energy ray-curable adhesive layer and the retardation layer are in contact with each other.
The following (1) to (3):
(1) Hold at a temperature of 30 ° C. or higher for 2 hours or longer.
(2) Hold for 2 hours or more under vibration conditions,
(3) A step of holding under the condition of satisfying any one or more of holding for 48 hours or more, and
The step of curing the active energy ray-curable adhesive layer to form the cured adhesive layer, and
A method for manufacturing an optical laminate, which comprises the above in this order.
[2] A method for manufacturing an optical laminate, which is a method for manufacturing an optical laminate.
The optical laminate includes an optical film, a cured adhesive layer which is a cured product layer of an active energy ray-curable adhesive, and a retardation layer including a cured product layer of a polymerizable liquid crystal compound in this order.
The manufacturing method is
A step of preparing a laminated body including a base film and the retardation layer laminated in contact with the base film, and
A step of peeling the base film from the retardation layer at a peeling rate of 50 m / min or more,
A step of laminating an optical film on the peeled surface of the retardation layer after peeling the base film via an active energy ray-curable adhesive layer.
The step of curing the active energy ray-curable adhesive layer to form the cured adhesive layer, and
A method for manufacturing an optical laminate, which comprises the above in this order.
[3] The method for producing an optical laminate according to [1] or [2], wherein the optical film contains a linear polarizer.
[4] In the laminating step, the optical film, the active energy ray-curable adhesive layer, and the retardation layer are laminated so that the linear polarizer and the active energy ray-curable adhesive layer are in contact with each other. The method for producing an optical laminate according to [3].
[5] An optical film, a cured adhesive layer which is a cured product layer of an active energy ray-curable adhesive, and a retardation layer including a cured product layer of a polymerizable liquid crystal compound are provided in this order.
The cured adhesive layer and the retardation layer are in contact with each other.
The surfaces of the retardation layer on the cured adhesive layer side are as follows (a) to (d):
(A) Arithmetic mean roughness Sa is 0.065 μm or more.
(B) The root mean square height Sq is 0.085 μm or more.
(C) The development area ratio Sdr of the interface is 0.2% or more.
(D) An optical laminate satisfying any one or more of the root mean square slope Sdq of 0.065 or more.
[6] The optical laminate according to [5], wherein the optical film contains a linear polarizer.
[7] The optical laminate according to [6], wherein the linear polarizer and the curing adhesive layer are in contact with each other.

Provided is an optical laminate comprising an optical film and a retardation layer including a cured product layer of a polymerizable liquid crystal compound, which is less likely to cause wrinkle defects even when curved with a small radius of curvature, and a method for producing the same. Can be done.

It is schematic cross-sectional view which shows an example of the layer structure of the laminated body obtained by the laminating step in Embodiment 1. FIG. It is the schematic sectional drawing which shows an example of the layer structure of an optical laminate. It is schematic cross-sectional view which shows an example of the layer structure of the laminated body prepared in the preparation process in Embodiment 2. FIG. It is a schematic cross-sectional view which shows an example of the layer structure of a linear polarizing plate. It is the schematic sectional drawing which shows an example of the layer structure of the retardation laminated body. It is the schematic sectional drawing which shows the other example of the layer structure of an optical laminate. It is the schematic sectional drawing which shows still another example of the layer structure of an optical laminate. It is a schematic diagram explaining the evaluation method of a wrinkle defect. It is a schematic diagram explaining the direction of the absorption axis and the slow phase axis in an optical laminate.

<Manufacturing method of optical laminate>
The optical laminate produced by the production method according to the present invention includes an optical film and a cured adhesive layer which is a cured product layer of an active energy ray-curable adhesive (hereinafter, also simply referred to as "cured adhesive layer"). And a retardation layer (hereinafter, also simply referred to as “phase difference layer”) including a cured product layer of the polymerizable liquid crystal compound are provided in this order.
The optical laminate produced by the production method according to the present invention can be suitably applied to an image display device such as an organic EL display device.

Hereinafter, embodiments of a method for manufacturing an optical laminate according to the present invention will be described with reference to the drawings. Each of the embodiments shown below may be arbitrarily combined. All drawings are schematic views and may not represent actual dimensions.
In each of the embodiments shown below, a long material may be used as the film or layer used in each step, and each step may be continuously performed, or a single-wafered material may be used as the film or layer used in each step, and each step. May be performed discontinuously. The single-leaved material may be cut from a long material.

[Embodiment 1]
The method for producing an optical laminate according to the present embodiment includes the following steps in the order described.
A step of laminating an optical film, an active energy ray-curable adhesive layer, and a retardation layer including a cured product layer of a polymerizable liquid crystal compound so that the active energy ray-curable adhesive layer and the retardation layer are in contact with each other. [Laminating process],
The following (1) to (3):
(1) Hold at a temperature of 30 ° C. or higher for 2 hours or longer.
(2) Hold for 2 hours or more under vibration conditions,
(3) A step of holding under the condition of satisfying any one or more of holding for 48 hours or more [holding step], and a step of curing the active energy ray-curable adhesive layer to form a cured adhesive layer [curing step]. ].

[1] Laminating Step FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the laminated body obtained by the laminating step in the present embodiment. The laminating step is a step of laminating the optical film 10 and the retardation layer 30 via the active energy ray-curable adhesive layer 20 (hereinafter, also simply referred to as “adhesive layer”). In the present specification, the active energy ray-curable adhesive layer means a layer composed of the active energy ray-curable adhesive. As the active energy ray-curable adhesive, one having an ability to bond the retardation layer 30 and the optical film 10 is used.

In the laminating step, the optical film 10, the adhesive layer 20, and the retardation layer 30 are laminated so that the adhesive layer 20 and the retardation layer 30 are in contact with each other. Further, the optical film 10, the adhesive layer 20, and the retardation layer 30 are preferably laminated so that the optical film 10 and the adhesive layer 20 are in contact with each other.

In the laminating step, the adhesive layer 20 is formed on one or more surfaces selected from the adhesive surface of the optical film 10 and the adhesive surface of the retardation layer 30, and the optical film 10 and the retardation layer 30 are formed via the adhesive layer 20. It can be carried out by laminating and. The adhesive layer 20 can be formed by applying an active energy ray-curable adhesive to the adhesive surface by a known coating method.
In the laminated body obtained by the laminating step, the thickness of the adhesive layer 20 is usually 0.5 μm or more and 50 μm or less, from the viewpoint of suppressing wrinkle defects, and from the viewpoint of adhesiveness between the optical film 10 and the retardation layer 30. From the viewpoint of thinning the obtained optical laminate, the thickness is preferably 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 20 μm or less.

Before forming the adhesive layer 20, plasma treatment, corona treatment, ultraviolet irradiation treatment, and frame (flame) are applied to one or more surfaces selected from the adhesive surface of the optical film 10 and the adhesive surface of the retardation layer 30. Surface activation treatment such as treatment and saponification treatment may be performed. By this surface activation treatment, the adhesiveness between the optical film 10 and the retardation layer 30 can be enhanced.

The optical film 10 may be a single-layer structure film or a multi-layer structure film. Examples of the optical film 10 include a linear polarizing plate and the like.
In the present specification, the linear polarizing plate is an optical element containing at least a linear polarizing element, and may include a linear polarizing element and a thermoplastic resin film or the like attached to at least one surface thereof.
When the optical film 10 is a linear polarizing plate, the linear polarizing element contained in the linear polarizing plate is preferably in contact with the adhesive layer 20 in the laminated body obtained by the laminating step.
The optical film 10 and the active energy ray-curable adhesive will be described in more detail in the section <Optical laminate> described later.

The retardation layer 30 includes a cured product layer of a polymerizable liquid crystal compound, and exhibits optical anisotropy according to the type of liquid crystal compound used to form the layer. Hereinafter, the cured product layer of this polymerizable liquid crystal compound is also referred to as a “phase difference expression layer”.
In the present specification, the retardation layer 30 may be composed of a retardation expression layer, or may include a retardation expression layer and an orientation layer.

In the laminating step, another one or more layers may be laminated in advance on the retardation layer 30 which is bonded to the optical film 10 via the adhesive layer 20 before the laminating step. For example, a retardation layer laminate including the retardation layer 30 and another retardation layer may be prepared in advance, and the retardation layer laminate may be bonded to the optical film 10 via the adhesive layer 20. Good.
The retardation layer, the retardation expression layer, the alignment layer, the retardation layer laminate and the like will be described in more detail in the section <Optical laminate> described later.

[2] Holding Step The holding step is a step of holding the laminated body obtained by the laminating step under specific conditions.
The specific mode of holding is not particularly limited, and examples thereof include allowing the laminate to stand under the specific conditions.

The above specific conditions are as follows (1) to (3):
(1) Hold at a temperature of 30 ° C. or higher for 2 hours or longer.
(2) Hold for 2 hours or more under vibration conditions,
(3) It is a condition that satisfies any one or more of holding for 48 hours or more.

According to the manufacturing method according to the present embodiment including the laminating step and the holding step, it is possible to manufacture an optical laminated body which is less likely to cause wrinkle defects even if it is curved with a small radius of curvature. This is presumed to be due to the following reasons.
The laminating step brings the retardation layer 30 into contact with the adhesive layer 20 before curing, and this state is maintained under the above specific conditions in the subsequent holding step. Since the active energy ray-curable adhesive before curing exerts an adhesive force on the retardation layer 30 after curing, it is recognized that an interaction with the retardation layer 30 acts. When the active energy ray-curable adhesive that interacts with the retardation layer 30 continues to be in contact with the retardation layer 30 under the above specific conditions, the contact surface of the retardation layer 30 with the adhesive. (Surface X shown in FIG. 1) is considered to be rough. Such roughness of the surface of the retardation layer 30 improves the adhesion with the adhesive layer 20.
When the adhesive force is improved, the cured adhesive layer (adhesive layer after curing) and the retardation layer 30 are integrally deformed when the optical laminate is curved, so that the occurrence of wrinkle defects is suppressed. It is thought that it will be easier to do.
The manufacturing method according to the present embodiment is also advantageous in suppressing rainbow unevenness, which will be described later, in the obtained optical laminate.

The holding temperature under the above condition (1) is 30 ° C. or higher, preferably 35 ° C. or higher, more preferably 38 ° C. or higher, still more preferably 40, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects. It is above ℃. The holding temperature is usually 55 ° C. or lower, and is preferably 50 ° C. or lower because the change in the water content can be reduced after the holding step is completed.

The holding time under the above condition (1) depends on the holding temperature, but is usually 2 hours or more, and is preferably 3 hours or more, more preferably 3 hours or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects. It is 4 hours or more, more preferably 5 hours or more. The holding time depends on the holding temperature, but usually less than 48 hours is sufficient. The holding time may be 48 hours or more, but in this case, the holding step satisfies the conditions (1) and (3).

The vibration applied to the laminated body under the above condition (2) can be performed, for example, by placing the laminated body on a vibration source. The vibration source is not particularly limited as long as it can vibrate with a constant period and a constant amplitude, and a vibration generator may be used, for example, it may rotate at a constant rotation speed. A rotating device such as an electric motor that can be used may be used, or a transformer or the like that can carry an alternating current may be used.
The frequency of the vibration is preferably 5 Hz or higher, more preferably 10 Hz or higher, from the viewpoint of suppressing the occurrence of wrinkle defects. The frequency of the vibration is preferably 50 Hz or less, more preferably 40 Hz or less, from the viewpoint of suppressing the occurrence of so-called floating in which the layers constituting the laminated body are partially separated from each other.
The amplitude of the vibration is preferably 0.5 mm or more, more preferably 1 mm or more, from the viewpoint of suppressing the occurrence of wrinkle defects. The amplitude of the vibration is preferably 30 mm or less, more preferably 10 mm or less, from the viewpoint of suppressing the occurrence of so-called floating in which the layers constituting the laminated body are partially separated from each other.

The holding temperature under the above condition (2) is not particularly limited, but is usually 5 ° C. or higher, preferably 10 ° C. or higher, more preferably 15 ° C. or higher, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects. Yes, more preferably 20 ° C. or higher. The holding temperature may be 30 ° C. or higher, but in this case, the holding step satisfies the conditions (1) and (2). The holding temperature is usually 55 ° C. or lower, and is preferably 50 ° C. or lower because the change in the water content can be reduced even after the holding step is completed.

The holding time under the above condition (2) depends on the holding temperature, but is usually 2 hours or more, and is preferably 3 hours or more, more preferably 3 hours or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects. It is 4 hours or more, more preferably 5 hours or more. The holding time depends on the holding temperature, but usually less than 48 hours is sufficient. The holding time may be 48 hours or more, but in this case, the holding step satisfies the conditions (2) and (3).

The holding temperature under the above condition (3) is not particularly limited, but is usually 5 ° C. or higher, preferably 10 ° C. or higher, more preferably 15 ° C. or higher, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects. Yes, more preferably 20 ° C. or higher. The holding temperature may be 30 ° C. or higher, but in this case, the holding step satisfies the conditions (1) and (3). The holding temperature is usually 55 ° C. or lower, and is preferably 50 ° C. or lower from the viewpoint that the change in the water content can be reduced even after the holding step is completed.

The holding time under the above condition (3) depends on the holding temperature, but is usually 48 hours or more, and is preferably 54 hours or more, more preferably 54 hours or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects. It is 66 hours or more, more preferably 72 hours or more. The holding time depends on the holding temperature, but usually 120 hours or less is sufficient.

Under any of the above conditions (1) to (3), the relative humidity of the environment in which the laminate is held is, for example, 20% RH or more and 80% RH or less, preferably 30% RH or more and 70% RH or less. is there.

[3] Curing Step With reference to FIG. 2, in this step, an optical laminate can be obtained by curing the adhesive layer 20 by irradiation with active energy rays to form a cured adhesive layer 20a. The type of active energy ray to be irradiated is appropriately selected according to the sensitive wavelength of the curable component contained in the active energy ray-curable adhesive constituting the adhesive layer 20 and the like. The active energy ray is preferably ultraviolet light.

[Embodiment 2]
The method for producing an optical laminate according to the present embodiment includes the following steps in the order described.
A step of preparing a laminate including a base film and a retardation layer laminated in contact with the base film [preparation step],
A step of peeling the base film from the retardation layer at a peeling speed of 50 m / min or more [peeling step], via an active energy ray-curable adhesive layer on the peeled surface of the retardation layer after peeling the base film. The process of laminating optical films [lamination process],
A step of curing an active energy ray-curable adhesive layer to form a cured adhesive layer [curing step].

[1] Preparation Step As described above, the retardation layer 30 includes a retardation expression layer (cured product layer of a polymerizable liquid crystal compound), and may be composed of a retardation expression layer or a retardation expression layer. It may include a layer and an orientation layer. Therefore, the laminate including the base film and the retardation layer laminated in contact with the base film prepared in this step has, for example, a layer structure of a base film / alignment layer / retardation expression layer. It may have a layer structure of a base film / retardation layer.

FIG. 3 is a schematic cross-sectional view showing an example of the layer structure of the laminated body prepared in the preparation step in the present embodiment. The laminate shown in FIG. 3 has a layer structure of a base film 41 / an alignment layer 32 / a retardation expression layer 31, and an example in which the retardation layer 30 is composed of a retardation expression layer 31 and an alignment layer 32. Is. As the laminate prepared in this step, one commercially available product or a combination of a plurality of commercially available products may be used.

The laminate prepared in this step may include a base film and a retardation layer laminated in contact with the base film, and is not limited to the example of FIG. One or two or more layers other than the base film 41 and the retardation layer 30 may be laminated on the laminate. For example, a retardation layer laminate including the base film 41, the retardation layer 30, and another retardation layer may be prepared in this step.
The base film, the retardation layer, the retardation expression layer, the alignment layer, the retardation layer laminate and the like will be described in more detail in the section <Optical laminate> described later.

[2] Peeling Step This step is a step of peeling the base film 41 from the retardation layer 30 at a peeling speed of 50 m / min or more.
The peeling speed is preferably 60 m / min or more, more preferably 70 m / min or more, still more preferably 80 m / min or more, and particularly preferably 80 m / min or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects. It is 90 m / min or more. The peeling speed is usually 150 m / min or less, and preferably 120 m / min or less from the viewpoint of preventing breakage of the base film.

The peeling angle of the base film 41 with respect to the laminate from which the base film 41 is peeled is usually larger than 90 degrees and 180 degrees or less. From the viewpoint of facilitating the peeling of the base film 41, the peeling angle is preferably 120 degrees or more and 180 degrees or less.
The peeling angle refers to an angle formed by the surface direction or transport direction of the laminated body when the base film 41 is peeled off and the surface direction or transport direction of the base film 41 to be peeled off.

When the laminate prepared in the preparation step has the base film 41, the alignment layer 32, and the retardation expression layer 31, when the base film 41 is peeled off, the alignment layer 32 is peeled off together with the base film 41. In this case, the surface of the phase difference developing layer 31 is exposed on the surface of the laminate by this step. When the alignment layer 32 remains on the laminate side without being peeled off, the surface of the alignment layer 32 is exposed on the surface of the laminate.
When the laminate prepared in the preparatory step has the base film 41 and the retardation layer 31 and does not have the alignment layer 32, the surface of the retardation layer 31 is on the surface of the laminate by this step. Is exposed.

[3] Laminating Step In this step, an optical film is formed on the peeled surface (exposed surface) of the retardation layer 30 after the base film 41 is peeled off, via the active energy ray-curable adhesive layer (adhesive layer) 20. This is a step of laminating 10. By this step, a layer structure similar to the layer structure shown in FIG. 1 is obtained. The peeled surface may be the surface of the alignment layer 32 or the surface of the retardation expression layer 31. As the active energy ray-curable adhesive, one having an ability to bond the retardation layer 30 and the optical film 10 is used.

In the laminating step, the adhesive layer 20 is formed on one or more surfaces selected from the adhesive surface of the optical film 10 and the adhesive surface (peeling surface) of the retardation layer 30, and the adhesive layer 20 is interposed with the optical film 10. It can be carried out by laminating the retardation layer 30. The adhesive layer 20 can be formed by applying an active energy ray-curable adhesive to the adhesive surface by a known coating method.
In the laminated body obtained by the laminating step, the thickness of the adhesive layer 20 is usually 0.5 μm or more and 50 μm or less, from the viewpoint of suppressing wrinkle defects, and from the viewpoint of adhesiveness between the optical film 10 and the retardation layer 30. From the viewpoint of thinning the obtained optical laminate, the thickness is preferably 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 20 μm or less.

Before forming the adhesive layer 20, one or more surfaces selected from the adhesive surface of the optical film 10 and the adhesive surface (peeling surface) of the retardation layer 30 are subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, etc. in advance. Surface activation treatment such as frame (flame) treatment and saponification treatment may be performed.
By this surface activation treatment, the adhesiveness between the optical film 10 and the retardation layer 30 can be enhanced.

The optical film 10 may be a single-layer structure film or a multi-layer structure film. Examples of the optical film 10 include a linear polarizing plate and the like.
When the optical film 10 is a linear polarizing plate, the linear polarizing element contained in the linear polarizing plate is preferably in contact with the adhesive layer 20 in the laminated body obtained by the laminating step.
The optical film 10 and the active energy ray-curable adhesive will be described in more detail in the section <Optical laminate> described later.

According to the manufacturing method according to the present embodiment including the peeling step and the laminating step, it is possible to manufacture an optical laminated body which is less likely to cause wrinkle defects even if it is curved with a small radius of curvature. This is presumed to be due to the following reasons.
When the base film 41 is peeled from the retardation layer 30 at a peeling speed of 50 m / min or more in the peeling step, the surface (peeling surface) of the retardation layer 30 after peeling is roughened. Such roughness of the surface of the retardation layer 30 improves the adhesive force with the adhesive layer 20 when the adhesive layer 20 is laminated and brought into contact with the surface in the subsequent laminating step.
When the adhesive force is improved, the cured adhesive layer (adhesive layer after curing) and the retardation layer 30 are integrally deformed when the optical laminate is curved, so that the occurrence of wrinkle defects is suppressed. It is thought that it will be easier to do.
The manufacturing method according to the present embodiment is also advantageous in suppressing rainbow unevenness, which will be described later, in the obtained optical laminate.

In the present embodiment, the peeling speed of the base film 41 is controlled as a means for roughening the surface of the retardation layer 30. As another means for roughening, for example, a base film having at least one surface roughened in advance is used, and a retardation layer 30 is formed on the roughened surface to prepare the surface. It may be a laminate prepared in the process.
The surface of the base film 41 can be roughened by a method of rubbing the surface or the like.

[4] Curing Step In this step, the adhesive layer 20 is cured by irradiation with active energy rays to form a cured adhesive layer 20a, whereby an optical laminate having the same layer structure as in FIG. 2 can be obtained. it can. For this step, the description of the curing step of the first embodiment is quoted.

<Optical laminate>
With reference to FIG. 2, the optical laminate according to the present invention (hereinafter, also simply referred to as “optical laminate”) is a cured adhesive which is a cured product layer of an optical film 10 and an active energy ray-curable adhesive. The layer 20a and the retardation layer 30 including the retardation expression layer (cured product layer of the polymerizable liquid crystal compound) are provided in this order.
The optical laminate can be suitably applied to an image display device such as an organic EL display device.

In the optical laminate, the cured adhesive layer 20a and the retardation layer 30 are in contact with each other. In the optical laminate, the optical film 10 and the cured adhesive layer 20a are preferably in contact with each other.

In the optical laminate, the surface (surface Xa in FIG. 2) on the curing adhesive layer 20a side of the retardation layer 30 has the following (a) to (d):
(A) Arithmetic mean roughness Sa is 0.065 μm or more.
(B) The root mean square height Sq is 0.085 μm or more.
(C) The development area ratio Sdr of the interface is 0.2% or more.
(D) Satisfy any one or more of the root mean square slope Sdq of 0.065 or more.

Arithmetic mean roughness Sa, square root mean square root height Sq, interface development area ratio Sdr, and root mean square slope Sdq are all indicators of surface roughness, and are based on ISO 25178 [Examples]. It is measured by the method described in the section.

Since the optical laminate according to the present invention satisfies any one or more of the above (a) to (d), wrinkle defects are unlikely to occur even if it is curved with a small radius of curvature. This is because the adhesion between the cured adhesive layer 20a and the retardation layer 30 is improved by the roughness of the surface of the retardation layer 30 on the side of the curing adhesive layer 20a, and therefore, the phase difference between the curing adhesive layer 20 and the curing adhesive layer 20a. It is considered that the layer 30 is because the optical laminate is integrally deformed when it is curved.

Further, an optical laminate satisfying any one or more of the above (a) to (d) is advantageous in that rainbow unevenness can be suppressed in the reflected light when viewed from the surface of the optical film 10 side. The ability to suppress rainbow unevenness is advantageous in improving the visibility of the optical laminate when it is applied to an image display device such as an organic EL display device.
An optical laminate satisfying any one or more of the above (a) to (d) can suppress rainbow unevenness because the reflected light generated by the light incident inside the optical laminate is reflected at the interface of each layer. This is thought to be because interference can be suppressed.

An optical laminate satisfying any one or more of the above (a) to (d) can be suitably produced by the production method according to the present invention described in the above section <Method for producing an optical laminate>.

From the viewpoint of more effectively suppressing the occurrence of wrinkle defects and rainbow unevenness, the optical laminate preferably satisfies any two or more of the above (a) to (d), and more preferably the above (a) to (a). Any 3 or more of (d) is satisfied, and more preferably all of the above (a) to (d) are satisfied.

The arithmetic mean roughness Sa in (a) above is preferably 0.067 μm or more, more preferably 0.070 μm or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects and rainbow unevenness. The arithmetic mean roughness Sa is usually 0.200 μm or less, and is preferably 0.150 μm or less from the viewpoint of reducing the internal haze of the optical laminate to ensure transparency and maintaining light transmittance.

The root mean square height Sq in (b) above is preferably 0.087 μm or more, more preferably 0.090 μm or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects and rainbow unevenness. The root mean square height Sq is usually 0.250 μm or less, and is preferably 0.200 μm or less from the viewpoint of reducing the internal haze of the optical laminate to ensure transparency and maintaining light transmittance.

The development area ratio Sdr of the interface in (c) above is preferably 0.25% or more, more preferably 0.3% or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects and rainbow unevenness. .. The development area ratio Sdr of the interface is usually 1.20% or less, and is preferably 1.10% or less from the viewpoint of reducing the internal haze of the optical laminate to ensure transparency and maintaining light transmittance. is there.

The root mean square slope Sdq in (d) above is preferably 0.070 or more, more preferably 0.072 or more, from the viewpoint of more effectively suppressing the occurrence of wrinkle defects and rainbow unevenness. The root mean square slope Sdq is usually 0.180 or less, and is preferably 0.160 or less from the viewpoint of reducing the internal haze of the optical laminate to ensure transparency and maintaining light transmittance.

Hereinafter, the elements that form or may form the optical laminate will be described.
[1] Optical film As described above, the optical film 10 may be a single-layer structure film or a multi-layer structure film.
Examples of the optical film 10 include a linear polarizing plate and a linear polarizer.

[2] Linear Polarizing Plate The linear polarizing plate is an optical element containing at least a linear polarizing element, and may further include a thermoplastic resin film or the like attached to at least one surface of the linear polarizing element. The linear polarized light refers to an optical element having a property of transmitting linearly polarized light having a vibrating surface orthogonal to the absorption axis when unpolarized light is incident.

The linear polarizer may be, for example, one in which a polyvinyl alcohol resin film is oriented and a dichroic dye such as iodine is adsorbed and oriented. The linear polarizer may be a monolayer polyvinyl alcohol resin film (polyvinyl alcohol molecules contained in the polyvinyl alcohol resin film oriented) with a bicolor dye adsorbed or oriented, and may be formed on the base film. It may be a laminated film having two or more layers provided with a polyvinyl alcohol resin layer in which a color dye is adsorbed and oriented. Such linear polarizers can be produced by various methods known in the art.
The thickness of the linear polarizer in which the dichroic dye is adsorbed and oriented on the single-layer polyvinyl alcohol resin film is preferably 20 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less.

The linear polarizer may be a cured film obtained by orienting a dichroic dye on a polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound. The linear polarizer is usually dried by applying a composition containing a polymerizable liquid crystal compound and a bicolor dye on a base film made of a thermoplastic resin film or the like or an alignment layer provided on the base film. However, it can be obtained by polymerizing and curing the polymerizable liquid crystal compound contained in the coating film by irradiation with active energy rays such as ultraviolet rays. The laminate of the base film and the linear polarizing element (cured film) thus obtained can be used as a linear polarizing plate.

The thickness of the base film for forming the cured film is not particularly limited, but generally, from the viewpoint of workability such as strength and handleability, it is preferably 1 μm or more and 300 μm or less, and more preferably 10 μm or more and 200 μm or less. It is more preferably 30 μm or more and 120 μm or less.

In the linear polarizing plate, examples of the thermoplastic resin film bonded to at least one surface of the linear polarizer include a polyolefin resin such as polyethylene and polypropylene; a cyclic polyolefin resin such as a norbornene polymer; polyethylene terephthalate and polyethylene. Polyester resin such as naphthalate; (meth) acrylic acid resin such as methyl poly (meth) acrylate; cellulose ester resin such as triacetyl cellulose, diacetyl cellulose and cellulose acetate propionate; polyvinyl alcohol and polyvinyl acetate Vinyl alcohol-based resins such as; polycarbonate-based resins; polystyrene-based resins; polyarylate-based resins; polysulfone-based resins; polyether sulfone-based resins; polyamide-based resins; polyimide-based resins; polyether ketone-based resins; polyphenylene sulfide-based resins; polyphenylene. Examples thereof include an oxide-based resin and a resin film composed of a mixture thereof, a copolymer and the like.
Among the above resins, it is preferable to use any one of cyclic polyolefin-based resin, polyester-based resin, cellulose ester-based resin and (meth) acrylic acid-based resin, or a mixture thereof.
In addition, "(meth) acrylic acid" means "at least one kind of acrylic acid and methacrylic acid".

The thermoplastic resin film may be a single layer obtained by mixing one kind or two or more kinds of resin materials, or may have a multilayer structure of two or more layers. When having a multi-layer structure, the resins constituting each layer may be the same or different from each other.
Any additive may be added to the thermoplastic resin film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an antioxidant, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.

The thickness of the thermoplastic resin film is preferably 2 μm or more and 300 μm or less, more preferably 5 μm or more and 200 μm or less, and further, from the viewpoint of thinning and flexibility of the optical laminate and the durability of the optical laminate. It is preferably 5 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and particularly preferably 5 μm or more and 30 μm or less.

The thermoplastic resin film can be laminated on the linear polarizer via an adhesive layer.
Examples of the adhesive forming the adhesive layer include water-based adhesives and active energy ray-curable adhesives.
Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like.
The active energy ray-curable adhesive is an adhesive that cures by irradiating with active energy rays such as ultraviolet rays, and includes, for example, a polymerizable compound and a photopolymerizable initiator, a photoreactive resin, and a binder. Examples thereof include those containing a resin and a photoreactive cross-linking agent. Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable (meth) acrylic monomer, and a photocurable urethane monomer, and oligomers derived from these monomers. .. Examples of the photopolymerization initiator include substances that generate active species such as neutral radicals, anion radicals, and cationic radicals by irradiating them with active energy rays such as ultraviolet rays.

The linear polarizing plate can further include a film or layer other than the above. Other films or layers include a protective film laminated on the surface of the linear polarizing plate; a reflective film placed at an appropriate position on the linear polarizing plate, a transflective reflective film, an optical compensation film, a film with an antiglare function, and the like. Examples include a retardation film.

The linear polarizing plate is preferably a single-protective polarizing plate in which a thermoplastic resin film is bonded to only one surface of the linear polarizing element, as shown in FIG. When the linear polarizing plate is a single-protective polarizing plate, the thickness thereof is thin, and as a result, the thickness of the optical laminate can be reduced. Therefore, for example, the organic EL display device provided with the optical laminate of the present invention can be easily applied as a flexible organic EL display device capable of bending, bending, winding, and the like.
When the optical film 10 is a single-protective polarizing plate, it is preferable that the linear polarizer is in contact with the cured adhesive layer 20a in the optical laminate.

[3] Curing Adhesive Layer The curing adhesive layer 20a is a cured product layer of an active energy ray-curable adhesive. The cured adhesive layer 20a can be formed by curing the active energy ray-curable adhesive layer (adhesive layer) 20 formed in the above-mentioned laminating step in the curing step.
As the active energy ray-curable adhesive, the same one as the active energy ray-curable adhesive described in the above [2] can be used.

In the optical laminate, the thickness of the cured adhesive layer 20a is usually 0.5 μm or more and 50 μm or less, from the viewpoint of suppressing wrinkle defects, from the viewpoint of adhesiveness between the optical film 10 and the retardation layer 30, and obtaining. From the viewpoint of thinning the optical laminate, the thickness is preferably 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 20 μm or less.

[4] Phase Difference Layer The phase difference layer 30 includes a retardation expression layer 31 which is a cured product layer of a polymerizable liquid crystal compound, and may further include an alignment layer 32.

The retardation expression layer 31 is formed by using a polymerizable liquid crystal compound, and a known polymerizable liquid crystal compound can be used. The type of the polymerizable liquid crystal compound is not particularly limited, and a rod-shaped liquid crystal compound, a disk-shaped liquid crystal compound, and a mixture thereof can be used. The polymerizable liquid crystal compound for forming the 1/4 wave plate having a reverse wavelength dispersibility is preferably a rod-shaped liquid crystal compound, for example, the polymerizable liquid crystal compound described in JP-A-2011-207765.

A composition for forming a retardation expression layer containing a polymerizable liquid crystal compound, a solvent, and various additives as necessary is applied onto the alignment layer 32 to form a coating film, and the coating film is cured. The retardation expression layer 31 which is a cured product layer of the polymerizable liquid crystal compound can be formed. Alternatively, the retardation expression layer forming composition may be directly applied onto the base film to form a coating film, and the coating film may be stretched together with the base film to form the retardation expression layer 31.
The thickness of the retardation expression layer 31 is usually 0.1 μm or more and 10 μm or less, preferably 0.2 μm or more and 5 μm or less.

The composition for forming a retardation layer may contain a polymerization initiator, a reactive additive, a leveling agent, a polymerization inhibitor and the like in addition to the above-mentioned polymerizable liquid crystal compound and solvent. As the polymerizable liquid crystal compound, the solvent, the polymerization initiator, the reactive additive, the leveling agent, the polymerization inhibitor and the like, known ones can be appropriately used.
Examples of the leveling agent that may be contained in the composition for forming the retardation expression layer and the retardation expression layer include a leveling agent containing an organically modified silicone oil as a main component and a leveling agent containing a polyacrylate compound as a main component. Examples thereof include leveling agents containing a fluorine atom-containing compound such as perfluoroalkyl as a main component. The main component refers to the component having the largest amount of all the components contained in the leveling agent. The content of the leveling agent in the composition for forming the retardation layer is preferably 0.01 parts by mass or more and 5 parts by mass or less, and more preferably 0.1 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound. It is 3 parts by mass or less.

The alignment layer 32, which may be included in the retardation layer 30, is a layer having an orientation restricting force for aligning the polymerizable liquid crystal compound contained in the liquid crystal layer formed on the retarding layer 30 in a desired direction. Examples of the oriented layer 32 include an oriented polymer layer formed of an oriented polymer, a photo-oriented polymer layer formed of a photo-aligned polymer, and a grub-aligned layer having a concavo-convex pattern and a plurality of grubs (grooves) on the layer surface. be able to.
The thickness of the alignment layer 32 is usually 10 nm or more and 500 nm or less, preferably 10 nm or more and 200 nm or less.

The oriented polymer layer can be formed by applying a composition in which the oriented polymer is dissolved in a solvent to the base film 41 to remove the solvent, and if necessary, performing a rubbing treatment. In this case, the orientation regulating force can be arbitrarily adjusted depending on the surface condition of the orientation polymer and the rubbing conditions.

The photooriented polymer layer can be formed by applying a composition containing a polymer or monomer having a photoreactive group and a solvent to the base film 41 and irradiating it with polarized light. In this case, in the photo-alignment polymer layer, the orientation-regulating force can be arbitrarily adjusted depending on the polarization irradiation conditions for the photo-orientation polymer.

The grub alignment layer is active on a plate-shaped master having grooves on the surface, for example, a method of forming a concavo-convex pattern by exposure, development, etc. through an exposure mask having a pattern-shaped slit on the surface of a photosensitive polyimide film. A method of forming an uncured layer of an energy ray-curable resin, transferring this layer to a base film 41 and curing it, forming an uncured layer of an active energy ray-curable resin on the base film 41, and this It can be formed by a method of forming irregularities and hardening them by pressing a roll-shaped master having irregularities against the layer.

As the base film 41, a resin film having the same structure as the above-mentioned thermoplastic resin film can be used.
The thickness of the base film 41 is not particularly limited, but generally, from the viewpoint of workability such as strength and handleability, it is preferably 1 μm or more and 300 μm or less, more preferably 10 μm or more and 200 μm or less, and further preferably 30 μm or more. It is 120 μm or less.
Any additive may be added to the base film 41. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an antioxidant, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.

[5] Laminated Layers As described above, in the laminating step of the first embodiment and the preparatory step of the second embodiment related to the method for manufacturing an optical laminated body, the retardation layer 30 and others are used as the retardation layer 30. A retardation layer laminate including the retardation layer and the retardation layer laminate of the above may be used.

FIG. 5 is a schematic cross-sectional view showing an example of the layer structure of the retardation laminate. The retardation laminate shown in FIG. 5 includes a base film 41, an alignment layer 32, a retardation expression layer 31, an adhesive layer 61, a retardation development layer 71, an alignment layer 72, and a base film 42 in this order. In the retardation layer shown in FIG. 5, the retardation layer 31 and the alignment layer 32 can be the retardation layer 30 which is bonded to the optical film 10 via the curing adhesive layer 20a in the optical laminate.
The retardation laminate shown in FIG. 5 may not have at least one of the alignment layer 32 and the alignment layer 72.

In the retardation laminate shown in FIG. 5, the combination of the retardation layer 31 and the retardation layer 71 is, for example, a combination of a 1/2 wave plate and a 1/4 wave plate, or an inverse wavelength dispersibility. It is a combination of the 1/4 wave plate and the positive C plate.
In the case of a combination of the 1/2 wave plate and the 1/4 wave plate, it is preferable that the retardation expression layer 31 arranged on the side closer to the optical film 10 in the optical laminate is the 1/2 wave plate.

When the retardation laminate shown in FIG. 5 is used in the lamination step of the first embodiment or the second embodiment according to the method for manufacturing an optical laminate, the base film 41 is peeled off from the retardation laminate. After that, it is laminated on the optical film 10 via the adhesive layer 20.
FIG. 6 shows an example of the layer structure of the optical laminate manufactured when the retardation laminate shown in FIG. 5 is used in the lamination step of the first embodiment or the second embodiment according to the method for manufacturing the optical laminate. It is a schematic cross-sectional view which shows. The optical laminate shown in FIG. 6 may not have at least one of the alignment layer 32 and the alignment layer 72.

The retardation laminate shown in FIG. 5 includes, for example, a laminate having a layer structure of a base film 41 / alignment layer 32 / retardation expression layer 31 and a substrate film 42 / alignment layer 72 / retardation expression layer 71. It can be manufactured by preparing or preparing a laminate having the above-mentioned layer structure and laminating these laminates via the adhesive layer 61.

Examples of the adhesive forming the adhesive layer 61 include a water-based adhesive and an active energy ray-curable adhesive. As these adhesives, the same adhesives as those described above that can be used for bonding the linear polarizer and the thermoplastic resin film can be used.
An adhesive layer can also be used as the adhesive layer 61. The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer is a composition in which a (meth) acrylic resin, a styrene resin, a silicone resin or the like is used as a base polymer, and a cross-linking agent such as an isocyanate compound, an epoxy compound or an aziridine compound is added. Can be mentioned.

The adhesive layer 61 is preferably a cured product layer of an active energy ray-curable adhesive such as an ultraviolet curable adhesive from the viewpoint of more effectively suppressing the occurrence of wrinkle defects.

[6] Adhesive Layer The optical laminate may further include an adhesive layer. FIG. 7 is a schematic cross-sectional view showing an example of the layer structure of the optical laminate having the pressure-sensitive adhesive layer 80.
The optical laminate shown in FIG. 7 can be manufactured, for example, by peeling the base film 42 from the optical laminate shown in FIG. 6 and laminating an adhesive layer on the peeled surface. A separate film may be laminated on the outer surface of the pressure-sensitive adhesive layer.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these examples.

<Example 1>
(1) Preparation of Linear Polarizing Plate A linear polarizer [thickness: 8 μm], which is a uniaxially stretched film formed by adsorbing and orienting iodine on a polyvinyl alcohol-based resin film, was prepared.
A first thermoplastic resin film is laminated on one surface of the linear polarizer via a polyvinyl alcohol-based adhesive, and a second thermoplastic resin film is laminated on the other surface of the linear polarizer, and a pair of patches is attached. A laminate having a layer structure of a first thermoplastic resin film / polyvinyl alcohol-based adhesive layer / linear polarizer / second thermoplastic resin film was obtained by passing it between the joint rolls.
No adhesive is interposed between the linear polarizer and the second thermoplastic resin film, and the second thermoplastic resin film is releasably laminated on the linear polarizer.

The following were used as the first thermoplastic resin film and the second thermoplastic resin film.
-First thermoplastic resin film: Clear hard coat film manufactured by Nippon Paper Industries Co., Ltd. Product name "COP20ST-HC" (film in which a clear hard coat layer is formed on a cyclic polyolefin resin film, thickness: 25 μm )
-Second thermoplastic resin film: Triacetyl cellulose (TAC) film manufactured by FUJIFILM Corporation, trade name "Fujitac" (thickness: 80 μm)

The obtained laminate was heat-treated at 80 ° C. for 300 seconds using a hot air dryer to dry the polyvinyl alcohol-based adhesive layer to obtain a linear polarizing plate.

(2) Preparation of Laminated Phase Difference Layer The retardation films 1 and 2 shown below and the active energy ray-curable adhesive 1 were prepared.
・ Phase difference film which is a 1/2 wave plate 1: Trade name "QL FILM QL AA 318" manufactured by FUJIFILM Corporation (base film 1 which is a TAC film having a thickness of 80 μm and the orientation formed on the base film 1). A retardation film having a total thickness of 2 μm composed of a layer 1 and a retardation expression layer 1 (in-plane retardation value 235 nm) which is a cured product layer (single layer) of a polymerizable liquid crystal compound formed on the layer 1).
Phase difference film 2: 1/4 wave plate: Trade name "QL FILM QL AB 318" manufactured by FUJIFILM Corporation (base film 2 which is a TAC film with a thickness of 80 μm and the orientation formed on the substrate film 2). A retardation film having a total thickness of 1 μm composed of a layer 2 and a retardation expression layer 2 (in-plane retardation value 120 nm) which is a cured product layer (single layer) of a polymerizable liquid crystal compound formed on the layer 2).
・ Active energy ray-curable adhesive 1: Cationic polymerizable UV-curable high-refractive index adhesive

The surface of the retardation expression layer 1 of the retardation film 1 and the surface of the retardation expression layer 2 of the retardation film 2 were subjected to corona treatment. The active energy ray-curable adhesive 1 is applied to each of the corona-treated surfaces of these retardation films using a bar coater so that the total thickness of the adhesive layer after curing is 1.5 μm, and then the retardation is achieved. The film 1 and the retardation film 2 are overlapped and passed between a pair of bonding rolls, and the base film 1 / alignment layer 1 / retardation expression layer 1 / active energy ray-curable adhesive 1 layer / retardation expression A laminate having a layer structure of layer 2 / alignment layer 2 / base film 2 was obtained.

The obtained laminate is irradiated with ultraviolet rays so that the integrated light intensity is 250 mJ / cm ² (UVB) using an ultraviolet irradiation device (the lamp uses a "D valve" manufactured by Fusion UV Systems). The layer of the active energy ray-curable adhesive 1 was cured by the above method to obtain a retardation layer laminate.

(3) Preparation of Optical Laminated Body 1 The second thermoplastic resin film of the linearly polarizing plate obtained in (1) above is peeled off, and the base material of the retardation layer laminated body obtained in (2) above is peeled off. The film 1 was peeled together with the alignment layer 1 at a peeling rate of 25 m / min. The peeling angle of the base film 1 with respect to the retardation layer laminate from which the base film 1 is peeled was set to 180 degrees.
Corona treatment was applied to the surface of the linear polarizer exposed by the peeling of the second thermoplastic resin film and the surface of the retardation developing layer 1 exposed by the peeling of the base film 1.
The alignment layer 1 was peeled off together with the base film 1.

After applying the active energy ray-curable adhesive 2 to the corona-treated surfaces of the linear polarizing plate and the retardation layer laminate using a bar coater so that the total thickness of the adhesive layer after curing is 2 μm, a straight line is formed. The polarizing plate and the retardation layer laminate are laminated and passed between a pair of bonding rolls to form a layer of a first thermoplastic resin film / polyvinyl alcohol-based adhesive layer / linear polarizer / active energy ray-curable adhesive 2. A laminate having a layer structure of / retardation layer 1 / cured product layer of active energy ray-curable adhesive 1 / retardation layer 2 / alignment layer 2 / base film 2 was obtained.

The following was used as the active energy ray-curable adhesive 2.
-Active energy ray-curable adhesive 2: Cationic polymerizable UV-curable adhesive

The obtained laminate was placed in a constant temperature and humidity chamber and held (standing) for 5 hours in an environment at a temperature of 40 ° C. (holding step). The relative humidity in the holding step was 55% RH (same for other examples and comparative examples).

After that, the laminated body is irradiated with ultraviolet rays so ^{that the integrated light amount becomes 400 mJ / cm 2} (UVB) using an ultraviolet irradiation device (the lamp uses an "H valve" manufactured by Fusion UV Systems). The layer of the active energy ray-curable adhesive 2 was cured to obtain an optical laminate 1. The environment at the time of ultraviolet irradiation was a temperature of 23 ° C. and a relative humidity of 55% RH (the same applies to other examples and comparative examples).
In the obtained optical laminate 1, the angle of the phase-advancing axis SL1 of the phase difference developing layer 1 (1/2 wavelength plate) with respect to the absorption axis PL of the linear polarizer is 75 °, and the phase difference expressing layer 2 (1 /). The angle of the phase-advancing axis SL2 of the 4-wave plate) was 15 °. The optical laminate 1 functioned as a circularly polarizing plate.

(4) Fabrication of Optical Laminated Body 2 (Lamination of Adhesive Layer on Optical Laminated Body 1)
The sheet-shaped adhesive 1 shown below was prepared.
-Sheet-like adhesive 1: Transfer-type non-carrier film ((meth) acrylic adhesive layer [thickness: 15 μm], a lightly peelable film laminated on one surface, and laminated on the other surface. Laminated film with a heavy-release film)

The base film 2 contained in the optical laminate 1 obtained in (3) above was peeled off together with the alignment layer 2, and the lightly peelable film contained in the sheet-like adhesive 1 was peeled off. Corona treatment was applied to the surface of the retardation developing layer 2 exposed by peeling the base film 2 and the surface of the pressure-sensitive adhesive layer exposed by peeling the lightly peelable film.
The alignment layer 2 was peeled off together with the base film 2.

The optical laminate 1 and the sheet-like adhesive 1 are laminated and passed between a pair of bonding rolls to pass a first thermoplastic resin film / polyvinyl alcohol-based adhesive layer / linear polarizer / active energy ray-curable adhesive 2 Obtained an optical laminate 2 having a layer structure of a cured product layer / retardation developing layer 1 / cured product layer of active energy ray-curable adhesive 1 / retardation developing layer 2 / adhesive layer / double peelable film. ..

<Example 2>
In the holding step, the optical laminate 1 was held in the same manner as in Example 1 except that the laminate was attached to the inner wall with a constant temperature and humidity chamber and held (standing) for 5 hours in a vibration environment having a frequency of 10 Hz and an amplitude of 1 mm. Made. The temperature environment in the holding step was 23 ° C. Further, the optical laminate 2 was produced in the same manner as in Example 1 except that the optical laminate 1 was used.

<Example 3>
In the holding step, the optical laminated body 1 was produced in the same manner as in Example 1 except that the laminated body was placed in a constant temperature and humidity chamber and held (standing) for 3 days in an environment of a temperature of 23 ° C. The relative humidity in the holding step was 55% RH. Further, the optical laminate 2 was produced in the same manner as in Example 1 except that the optical laminate 1 was used.

<Example 4>
(1) Preparation of Linear Polarizing Plate A linear polarizing plate was produced in the same manner as in Example 1.

(2) Preparation of Phase Difference Layer Laminated Body A retardation layer laminate was produced in the same manner as in Example 1.

(3) Preparation of Optical Laminated Body 1 The second thermoplastic resin film of the linearly polarizing plate obtained in (1) above is peeled off together with the alignment layer 1, and the retardation layer laminated body obtained in (2) above is peeled off. The base film 1 contained in the film was peeled off at a peeling rate of 90 m / min. The peeling angle of the base film 1 with respect to the retardation layer laminate from which the base film 1 is peeled was set to 180 degrees.
After that, the optical laminate 1 was produced in the same manner as in Example 1 except that the holding step was not performed.

(4) Fabrication of Optical Laminated Body 2 (Lamination of Adhesive Layer on Optical Laminated Body 1)
An optical laminate 2 was produced in the same manner as in Example 1 except that the optical laminate 1 obtained in (3) above was used.

<Comparative example 1>
In the holding step, the optical laminated body 1 was produced in the same manner as in Example 1 except that the laminated body was placed in a constant temperature and humidity chamber and held (standing) for 5 hours in an environment of a temperature of 23 ° C. The relative humidity in the holding step was 55% RH. Further, the optical laminate 2 was produced in the same manner as in Example 1 except that the optical laminate 1 was used.

<Comparative example 2>
First thermoplastic resin film / polyvinyl alcohol-based adhesive layer / linear polarizer / active energy ray-curable adhesive 2 layer / retardation developing layer 1 / active energy ray-curable adhesive without carrying out a holding step After obtaining a laminated body having a layer structure of a cured product layer of the agent 1, a retardation expressing layer 2 and a base film 2, the layer of the active energy ray-curable adhesive 2 was cured by immediately irradiating with ultraviolet rays. An optical laminate 1 was produced in the same manner as in Example 1 except for the above. Further, the optical laminate 2 was produced in the same manner as in Example 1 except that the optical laminate 1 was used.

<Comparative example 3>
(1) Preparation of a linearly polarizing plate with an adhesive layer A linearly polarizing plate was produced in the same manner as in Example 1.
In addition, the sheet-shaped adhesive 2 shown below was prepared.
-Sheet-like pressure-sensitive adhesive 2: A transfer-type non-carrier film ((meth) acrylic pressure-sensitive adhesive layer [thickness: 5 μm], a lightly peelable film laminated on one surface, and laminated on the other surface. Laminated film with a heavy-release film)

The second thermoplastic resin film of the linear polarizing plate was peeled off, and the lightly peelable film of the sheet-like pressure-sensitive adhesive 2 was peeled off. Corona treatment was applied to the surface of the linear polarizer exposed by peeling the second thermoplastic resin film and the surface of the pressure-sensitive adhesive layer exposed by peeling the lightly peelable film.
After that, the sheet-like adhesive 2 from which the lightly peelable film was peeled off was laminated on the surface (corona-treated surface) of the linear polarizer on the corona-treated surface side, and the first thermoplastic resin film / polyvinyl alcohol-based adhesive layer was laminated. A linear polarizing plate with an adhesive layer having a layer structure of / linear polarizer / adhesive layer / double-release film was obtained.

(3) Preparation of Optical Laminated Body 1 The heavy-release film of the linearly polarizing plate with an adhesive layer obtained in (1) above is peeled off, and the retardation layer laminated body obtained in (2) above has. The base film 1 was peeled together with the alignment layer 1 at a peeling rate of 25 m / min. The peeling angle of the base film 1 with respect to the retardation layer laminate from which the base film 1 is peeled was set to 180 degrees.
Corona treatment was applied to the surface of the pressure-sensitive adhesive layer exposed by peeling the heavy-release film and the surface of the retardation-developing layer 1 exposed by peeling the base film 1.
The alignment layer 1 was peeled off together with the base film 1.

After that, the retardation layer laminate is laminated on the corona-treated surface of the linear polarizing plate with the pressure-sensitive adhesive layer on the corona-treated surface side, and the first thermoplastic resin film / polyvinyl alcohol-based adhesive layer / linear polarizer / pressure-sensitive adhesive is used. An optical laminate 1 having a layer structure of a layer / retardation developing layer 1 / cured product layer of active energy ray-curable adhesive 1 / retardation developing layer 2 / base film 2 was obtained.

[Measurement / evaluation]
(1) Measurement of Surface Roughness A rectangular laminate piece having a length of 50 mm (long side) and a width of 15 mm with the absorption axis of the linear polarizer as the length direction is cut out from the optical laminate 2 to form a heavy-release film. The adhesive layer is peeled off to expose it, and the exposed adhesive layer is attached to an acrylic plate (black) to form a test piece [first thermoplastic resin film / polyvinyl alcohol-based adhesive layer / linear polarizer / active energy ray curing. It has a layer structure of a cured product layer of the sex adhesive 2 / a retardation developing layer 1 / a cured product layer of the active energy ray-curable adhesive 1 / a retardation developing layer 2 / an adhesive layer / an acrylic plate (black). ]. This test piece is exposed to light from the first thermoplastic resin film side, conforms to ISO 25178, and is subjected to a layer cross-section analysis mode by a scanning white interference microscope "VertScan" (Hitachi is manufactured by TechScience Co., Ltd.). Measures the arithmetic average roughness Sa, the square mean square root height Sq, the developing area ratio Sdr of the interface, and the root mean square slope Sdq of the surface on the linear polarizer side in the retardation layer (phase contrast expression layer 1). did. The results are shown in Table 1. The measurement conditions were as follows.
Camera: Sony "XCL-32"
Objective lens: 5CTI
Lens barrel: 1.0X
Zoom lens: 1X
Light source: 530 White
Measurement device: Piezo Measurement mode: Wave

(2) Evaluation of Wrinkle Defects A test piece (rectangle) having a length of 50 mm (long side) and a width of 15 mm (short side) with the absorption axis of the linear polarizer as the length direction was cut out from the optical laminate 1.
As shown in FIG. 8, the test piece (S) is curved so that the two short sides (S1) face each other to form a curved portion (C) at the center in the long side direction, and while maintaining this state. Curvature diameter (R) of the curved portion of the test piece by reducing the distance between the two glass plates (G) while holding between the two glass plates (flat plates) (G) arranged parallel to each other. ) Was reduced to 10 mm, and then an expansion step of widening the distance between the two glass plates until the bending state was eliminated was repeated 10 times to perform a 10 mm bending test. The two short sides (S1) of the test piece (S) were fixed to the glass plate (G), respectively.
If no wrinkle defect occurs in the test piece after the 10 mm bending test, the reduction step and the expansion step are repeated 10 times in the same manner as above except that the curvature diameter R of the bent portion is further set to 5 mm for the same test piece. The test was conducted.
If no wrinkle defect occurs in the test piece after the 5 mm bending test, the reduction step and the expansion step are repeated 10 times in the same manner as above except that the curvature diameter R of the bent portion is further set to 4 mm for the same test piece. The test was conducted.
If no wrinkle defect occurs in the test piece after the 4 mm bending test, the reduction step and the expansion step are repeated 10 times in the same manner as above except that the curvature diameter R of the bent portion is further set to 3 mm for the same test piece. The test was conducted.
If no wrinkle defect occurs in the test piece after the 3 mm bending test, the reduction step and the expansion step are repeated 10 times in the same manner as above except that the curvature diameter R of the bent portion is further set to 2 mm for the same test piece. The test was conducted.

The portion of the test piece wound around the mandrel was visually observed, and the resistance to wrinkle defects was evaluated according to the following criteria. The results are shown in Table 1.
A: No wrinkle defect is observed even after starting from the 10 mm bending test and finishing the 2 mm bending test.
B: No wrinkle defect was observed even after starting from the 10 mm bending test and completing the 3 mm bending test, but when the 2 mm bending test was continued, wrinkle defects occurred.
C: No wrinkle defect was observed even after starting from the 10 mm bending test and completing the 4 mm bending test, but when the 3 mm bending test was continued, wrinkle defects occurred.

The absorption axis (PL) of the linear polarizer, the phase advance axis (SL1) of the retardation expression layer 1 and the phase advance axis (SL2) of the retardation expression layer 2 in each test piece are viewed from the linear polarizer side. It was as shown in FIG. That is, the absorption axis (PL) is + 135 ° with respect to the short side, and the phase advance axis (SL1) is the short side, assuming that the counterclockwise direction is positive (+) when viewed from the first thermoplastic resin film side (linear polarizer side). The phase advance axis (SL2) was + 60 ° with respect to the short side. Each test piece functions as a circularly polarizing plate.

(3) Evaluation of Rainbow Unevenness A test piece (rectangle) having a size of 100 mm in length × 100 mm in width was cut out from the optical laminate 2. The heavy-release film was peeled off from this test piece and bonded to a flat black acrylic plate using an exposed adhesive layer. Further, a glass plate [Non-alkali glass "Eagle XG" manufactured by Corning Inc., thickness 0.7 mm] is laminated on the first thermoplastic resin film, which is the uppermost layer of the optical laminate 2, via a water film for evaluation. It was made into a laminated body.

The obtained evaluation laminate was placed in a room with a fluorescent lamp. The position of the fluorescent lamp was 250 mm above the black acrylic plate. In this state, the reflected light of the light from the fluorescent lamp was visually observed from the surface (the surface on the glass plate side) side of the evaluation laminate, and the resistance to rainbow unevenness was evaluated according to the following criteria. The results are shown in Table 1. The reflected light of the light from the fluorescent lamp means the light emitted from the glass plate side by reflecting the light from the fluorescent lamp incident on the inside of the optical laminate 2 at the interface of each layer.
A: No rainbow unevenness is observed in the reflected light.
B: Very slight rainbow unevenness is observed in the reflected light.
C: Rainbow unevenness is observed in the reflected light (rainbow unevenness is observed more clearly than B).

10 Optical film,
20 Active energy ray-curable adhesive layer (adhesive layer),
20a hardened adhesive layer,
30 phase difference layer,
31 Phase difference expression layer,
32 Orientation layer,
41 Base film,
42 base film,
50 linear polarizer,
51 Adhesive layer,
52 Thermoplastic resin film,
61 Adhesive layer,
71 Phase difference expression layer,
72 Orientation layer,
80 Adhesive layer.

Claims

A method for manufacturing an optical laminate,
The optical laminate includes an optical film, a cured adhesive layer which is a cured product layer of an active energy ray-curable adhesive, and a retardation layer including a cured product layer of a polymerizable liquid crystal compound in this order.
The manufacturing method is
A step of laminating the optical film, the active energy ray-curable adhesive layer, and the retardation layer so that the active energy ray-curable adhesive layer and the retardation layer are in contact with each other.
The following (1) to (3):
(1) Hold at a temperature of 30 ° C. or higher for 2 hours or longer.
(2) Hold for 2 hours or more under vibration conditions,
(3) A step of holding under the condition of satisfying any one or more of holding for 48 hours or more, and
The step of curing the active energy ray-curable adhesive layer to form the cured adhesive layer, and
A method for manufacturing an optical laminate, which comprises the above in this order.
A method for manufacturing an optical laminate,
The optical laminate includes an optical film, a cured adhesive layer which is a cured product layer of an active energy ray-curable adhesive, and a retardation layer including a cured product layer of a polymerizable liquid crystal compound in this order.
The manufacturing method is
A step of preparing a laminated body including a base film and the retardation layer laminated in contact with the base film, and
A step of peeling the base film from the retardation layer at a peeling rate of 50 m / min or more,
A step of laminating an optical film on the peeled surface of the retardation layer after peeling the base film via an active energy ray-curable adhesive layer.
The step of curing the active energy ray-curable adhesive layer to form the cured adhesive layer, and
A method for manufacturing an optical laminate, which comprises the above in this order.
The method for producing an optical laminate according to claim 1 or 2, wherein the optical film contains a linear polarizer.
In the laminating step, the optical film, the active energy ray-curable adhesive layer, and the retardation layer are laminated so that the linear polarizer and the active energy ray-curable adhesive layer are in contact with each other. Item 3. The method for producing an optical laminate according to Item 3.
An optical film, a cured adhesive layer which is a cured product layer of an active energy ray-curable adhesive, and a retardation layer including a cured product layer of a polymerizable liquid crystal compound are provided in this order.
The cured adhesive layer and the retardation layer are in contact with each other.
The surfaces of the retardation layer on the cured adhesive layer side are as follows (a) to (d):
(A) Arithmetic mean roughness Sa is 0.065 μm or more.
(B) The root mean square height Sq is 0.085 μm or more.
(C) The development area ratio Sdr of the interface is 0.2% or more.
(D) An optical laminate satisfying any one or more of the root mean square slope Sdq of 0.065 or more.
The optical laminate according to claim 5, wherein the optical film contains a linear polarizer.
The optical laminate according to claim 6, wherein the linear polarizer and the cured adhesive layer are in contact with each other.