Optical stack

Abstract

The present invention provides an optical laminate in which a release film having an antistatic layer is laminated on a polarizing plate, and which exhibits excellent quality control properties. [Solution] The optical laminate consists of a polarizing plate containing a linearly polarizing layer, a first adhesive layer, and a release film that can be peeled off from the first adhesive layer, laminated in this order. The release film has, in order from the first adhesive layer side, a release treatment layer, a first base film, and a first antistatic layer containing an antistatic agent. The average in-plane phase difference value of the release film at a wavelength of 550 nm is 1000 nm or more. The difference between the maximum and minimum values ​​of the in-plane phase difference value of the release film at a wavelength of 550 nm is 150 nm or less.

Description

[Technical Field]

[0001] This invention relates to an optical laminate. [Background technology]

[0002] Polarizing plates containing a linear polarizing layer are used as optical components in display devices such as liquid crystal displays and organic EL displays. When incorporating a polarizing plate into a display device, it is usually bonded to an image display element such as a display panel via an adhesive layer. To facilitate the process of incorporating a polarizing plate into a display device, it is known to pre-laminated an adhesive layer and a release film that can be peeled off from this adhesive layer onto the polarizing plate. By peeling off the release film from the polarizing plate with the adhesive layer and release film laminated on it, and bonding the exposed adhesive layer to the image display element, the polarizing plate can be incorporated into the display device.

[0003] Patent Document 1 discloses the use of a surface protection film to prevent scratches on the surface of a reinforcing film used to impart rigidity and impact resistance to optical components, electronic components, etc. In polarizing plates, it is known that a surface protection film that can be peeled off from the polarizing plate is laminated to the surface of the polarizing plate to suppress scratches and other damage to the surface caused by processing, assembly, inspection, transportation, etc.

[0004] A stretched film, obtained by stretching a resin film, may be used as a release film and a surface protection film. The stretched film has an in-plane phase difference. Therefore, by laminating the stretched film and a polarizing plate so that the slow axis of the stretched film and the absorption axis of the linearly polarized layer are parallel or perpendicular, the polarizing plate can be inspected by observing the transmission of light using crossed nicols with this laminate.

[0005] Laminates of polarizing plates and stretched films are stored in a stacked state, and during inspection, the plates are removed one by one from the stack. At this time, due to the influence of static electricity, two or more plates were sometimes removed simultaneously, a phenomenon known as "multiple removal." To suppress such multiple removals, it is conceivable to use a resin film with an antistatic layer formed on its surface to suppress static electricity. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-116762 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, stretched films equipped with an antistatic layer may exhibit uneven in-plane phase differences. When observing light transmission using crossed nicols with a laminate of such a stretched film laminated onto a polarizing plate, it becomes difficult to inspect the polarizing plate.

[0008] The present invention aims to provide an optical laminate in which at least one of a release film having an antistatic layer and a surface protective film having an antistatic layer is laminated on a polarizing plate, and which has excellent inspectability. [Means for solving the problem]

[0009] The present invention provides the following optical laminate. [1] An optical laminate comprising a polarizing plate containing a linearly polarizing layer, a first adhesive layer, and a release film that can be peeled off from the first adhesive layer, in this order, The release film has, in order from the first adhesive layer side, a release treatment layer, a first base film, and a first antistatic layer containing an antistatic agent. The average in-plane phase difference value of the aforementioned release film at a wavelength of 550 nm is 1000 nm or more. An optical laminate in which the difference between the maximum and minimum in-plane phase difference values ​​of the release film at a wavelength of 550 nm is 150 nm or less. [2] Furthermore, the polarizing plate has a surface protective film that can be peeled off from the polarizing plate on the side opposite to the first adhesive layer, The optical laminate according to [1], wherein the surface protective film comprises, in order from the polarizing plate side, a second base film and a second antistatic layer containing an antistatic agent. [3] The average in-plane phase difference value of the surface protective film at a wavelength of 550 nm is 1000 nm or more. The optical laminate according to [2], wherein the difference between the maximum and minimum in-plane phase difference values ​​of the surface protective film at a wavelength of 550 nm is 150 nm or less. [4] An optical laminate comprising a first adhesive layer, a polarizing plate including a linear polarizing layer, and a surface protective film that can be peeled off from the polarizing plate, in this order, The surface protective film comprises, in order from the polarizing plate side, a second base film and a second antistatic layer containing an antistatic agent. The average in-plane phase difference value of the surface protective film at a wavelength of 550 nm is 1000 nm or more. An optical laminate in which the difference between the maximum and minimum in-plane phase difference values ​​of the surface protective film at a wavelength of 550 nm is 150 nm or less. [5] The optical laminate according to any one of [2] to [4], wherein the surface protective film further has a second adhesive layer on the polarizing plate side of the second substrate film. [6] Furthermore, the first adhesive layer has a release film on the side opposite to the polarizing plate side that is peelable from the first adhesive layer, The optical laminate according to [4] or [5], wherein the release film has, in order from the first adhesive layer side, a release treatment layer, a first base film, and a first antistatic layer containing an antistatic agent. [7] Furthermore, the first adhesive layer has a release film on the side opposite to the polarizing plate side that is peelable from the first adhesive layer, The release film has, in order from the first adhesive layer side, a release treatment layer, a first base film, and a first antistatic layer containing an antistatic agent. The surface resistance of the aforementioned release film at a temperature of 23°C and a relative humidity of 55%RH is 1.0 × 10⁻⁶ 8 Ω / □ or more 5.0×10 14 An optical laminate as described in [1] to [6], wherein the Ω / □ is less than or equal to Ω. [8] Furthermore, the polarizing plate has a surface protective film that can be peeled off from the polarizing plate on the side opposite to the first adhesive layer, The surface protective film comprises, in order from the polarizing plate side, a second base film and a second antistatic layer containing an antistatic agent. The surface resistance of the aforementioned surface protective film at a temperature of 23°C and a relative humidity of 55%RH is 1.0 × 10⁻⁶ 8 Ω / □ or more 1.0×10 11 An optical laminate described in any of [1] to [7], wherein the Ω / □ is less than or equal to Ω. [9] The optical laminate according to any one of [1] to [8], wherein the polarizing plate has a protective layer on one or both sides of the linear polarizing layer.

[10] A method for manufacturing an optical laminate having, in this order, a polarizing plate containing a linearly polarizing layer, a first adhesive layer, and a release film that can be peeled off from the first adhesive layer, The release film has, in order from the first adhesive layer side, a release treatment layer, a first base film, and a first antistatic layer containing an antistatic agent. The average in-plane phase difference value of the aforementioned release film at a wavelength of 550 nm is 1000 nm or more. The process involves applying a coating liquid containing the antistatic agent to the first substrate film to form a first coating layer, A method for manufacturing an optical laminate, comprising the step of drying the first coating layer at a temperature of 60°C or lower to form the first antistatic layer.

[11] A method for manufacturing an optical laminate in which a first adhesive layer, a polarizing plate including a linear polarizing layer, and a surface protective film that can be peeled off from the polarizing plate are laminated in this order, The surface protective film comprises, in order from the polarizing plate side, a second base film and a second antistatic layer containing an antistatic agent. The average in-plane phase difference value of the surface protective film at a wavelength of 550 nm is 1000 nm or more. The process involves applying a coating liquid containing the antistatic agent to the second substrate film to form a second coating layer, A method for manufacturing an optical laminate, comprising the step of drying the second coating layer at a temperature of 60°C or lower to form the second antistatic layer. [Effects of the Invention]

[0010] According to the present invention, even if an optical laminate is formed in which at least one of a release film having an antistatic layer and a surface protective film having an antistatic layer is laminated on a polarizing plate, it can have excellent inspection properties. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing an optical laminate according to one embodiment of the present invention. [Figure 2] Figure 1 is a schematic cross-sectional view illustrating an example of a cross-nicol inspection method for an optical stack shown in Figure 1. [Figure 3] This is a schematic cross-sectional view showing an optical laminate according to another embodiment of the present invention. [Figure 4] Figure 3 is a schematic cross-sectional view illustrating an example of a cross-nicol inspection method for an optical stack shown in Figure 3. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the optical laminate of the present invention will be described with reference to the drawings. The embodiments shown below may be combined in any way. In each embodiment and each drawing, the same or corresponding reference numerals are used for members that have been described earlier, and their descriptions may not be repeated.

[0013] [Embodiment 1] (Optical laminate 1) Figure 1 is a schematic cross-sectional view showing an optical laminate according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view showing an example of a cross-nicol inspection method for the optical laminate shown in Figure 1.

[0014] As shown in Figure 1, the optical laminate 1 is constructed by laminating a polarizing plate 10 containing a linear polarizing layer, a first adhesive layer 11, and a release film 20 that can be peeled off from the first adhesive layer 11 in this order. In the optical laminate 1 shown in Figure 1, the polarizing plate 10 and the first adhesive layer 11 are in direct contact, and the first adhesive layer 11 and the release film 20 are in direct contact.

[0015] The optical laminate 1 may further have a surface protective film 30 on the side of the polarizing plate 10 opposite to the first adhesive layer 11 side, which can be peeled off from the polarizing plate 10.

[0016] The polarizing plate 10 of the optical laminate 1 can be incorporated into a display device. When incorporating the polarizing plate 10 into a display device, the release film 20 is peeled off from the optical laminate 1, the exposed first adhesive layer 11 is bonded to the image display element of the display device, and then the surface protective film 30 is peeled off. Examples of display devices include liquid crystal displays and organic EL displays, and examples of image display elements include liquid crystal display elements and organic EL display elements.

[0017] (Polarizing plate) The optical laminate 1 includes a polarizing plate 10. The polarizing plate 10 may include at least a linear polarizing layer, and may also include layers other than the linear polarizing layer. For example, the polarizing plate 10 may have a protective layer on one or both sides of the linear polarizing layer, or it may have a surface functional layer on the surface of the protective layer. If the polarizing plate 10 has a protective layer, the protective layer may be laminated so as to be in direct contact with the linear polarizing layer, or the linear polarizing layer and the protective layer may be laminated with a bonding layer in between. The bonding layer is an adhesive layer or a bonding agent layer. Details of each layer will be described later.

[0018] (1st adhesive layer) The optical laminate 1 has a first adhesive layer 11. The first adhesive layer 11 can be used as an adhesive layer for bonding the polarizing plate 10 to an image display element or the like. Preferably, the first adhesive layer 11 is laminated so as to be in direct contact with the polarizing plate 10. Details of the first adhesive layer 11 will be described later.

[0019] (Release film 20) The optical laminate 1 has a release film 20. The release film 20 is for covering and protecting the first adhesive layer 11, and in the optical laminate 1, it is laminated to the first adhesive layer 11 in a peelable manner. The release film 20 has an in-plane phase difference value of a size described later, and in the optical laminate 1, the slow axis of the release film 20 and the absorption axis of the linearly polarized layer are substantially parallel or substantially orthogonal. Here, substantially parallel means that the angle between the slow axis of the release film 20 and the absorption axis of the linearly polarized layer is within 0°±10°, preferably within 0°±5°, and more preferably 0°. Substantially orthogonal means that the angle between the slow axis of the release film 20 and the absorption axis of the linearly polarized layer is within 90°±10°, preferably within 90°±5°, and more preferably 90°.

[0020] As shown in FIG. 1, the release film 20 has, in order from the side of the first adhesive layer 11 of the optical laminate 1, a release treatment layer 22, a first base film 21, and a first antistatic layer 23 containing an antistatic agent. It is preferable that the release treatment layer 22 and the first base film 21 are in direct contact. It is preferable that the first base film 21 and the first antistatic layer 23 are in direct contact. Details of each layer will be described later.

[0021] The average in-plane retardation value Re at a wavelength of 550 nm of the release film 20 A1 is 1000 nm or more. The above average in-plane retardation value Re A1 may be 1500 nm or more, may be 1800 nm or more, or may be 2000 nm or more. The above average in-plane retardation value Re A1 is usually 5000 nm or less, may be 4000 nm or less, or may be 3000 nm or less.

[0022] The above average in-plane retardation value Re of the release film 20 A1 can be adjusted, for example, by the in-plane retardation value of the first base film 21. The in-plane retardation value of the first base film 21 can be adjusted, for example, by the type of resin constituting the first base film 21, the draw ratio, etc. The above average in-plane retardation value Re A1 can be determined by the method described in the examples below.

[0023] Let the maximum value of the in-plane retardation value at a wavelength of 550 nm of the release film 20 be Re ma1 and the minimum value of the in-plane retardation value at a wavelength of 550 nm of the release film 20 be Re mi1 When doing so, the difference ΔRe1 (= Re ma1 - Re mi1 ) is 150 nm or less. The difference ΔRe1 may be 130 nm or less, may be 110 nm or less, may be 100 nm or less, may be 80 nm or less, or may be 60 nm or less. The difference ΔRe1 is usually 5 nm or more, may be 10 nm or more, or may be 20 nm or more.

[0024] The above-mentioned difference ΔRe1 of the release film 20 can be adjusted by the method of forming the first antistatic layer 23 on the first base film 21, etc. For example, as will be described later, it can be adjusted by the temperature at which the coating layer formed by applying a coating liquid containing an antistatic agent to the first base film 21 is dried. The above-mentioned difference ΔRe1 can be determined by the method described in the examples described later.

[0025] The release film 20 included in the optical laminate 1 has a first antistatic layer 23 to suppress the simultaneous removal of two or more optical laminates 1 when removing one optical laminate 1 at a time from a superimposed optical laminate 1. In a release film with an antistatic layer, the in-plane phase difference value of the release film may not be uniform and may vary. Inspection of the polarizing plate 10 may be performed by light transmission observation using crossed nicols with the optical laminate 1. In this case, if the variation in the in-plane phase difference value of the release film is large, unevenness in the phase difference will be visible in light transmission observation using crossed nicols with the optical laminate including the polarizing plate and the release film, making it difficult to properly inspect the polarizing plate for defects, etc. This phenomenon is particularly noticeable when the release film 20 of the optical laminate 1 is placed between the linear polarization layer of the inspection polarizing plate 60, which is arranged to be crossed nicols, and the linear polarization layer of the optical laminate 1, as shown in Figure 2. The arrows in Figure 2 indicate the direction in which the light from the light source 61 should be observed when inspecting the polarizing plate 10.

[0026] In contrast, even though the optical laminate 1 has a first antistatic layer 23, the difference ΔRe1 of the release film 20 is within the above range, so the amount of fluctuation in the in-plane phase difference value is small, and unevenness in the phase difference is difficult to see when observing light transmission with crossed nicols using the optical laminate 1. Therefore, since the polarizer plate 10 can be inspected by observing light transmission with crossed nicols using the optical laminate 1, the optical laminate 1 has excellent inspection properties.

[0027] The surface resistance of release film 20 at a temperature of 23°C and a relative humidity of 55%RH is 1.0 × 10⁻⁶. 8Ω / □ or more 5.0×10 14 It is preferable that the surface resistance is Ω / □ or less. The above surface resistance value of the release film 20 is 1.0 × 10 9 It may be greater than or equal to Ω / □, and 1.0 × 10 10 It may be greater than or equal to Ω / □, and also 1.0 × 10 14 It may be less than or equal to Ω / □, and 5.0 × 10 13 It may be less than or equal to Ω / □, and 1.0 × 10 13 It may be less than or equal to Ω / □.

[0028] The surface resistance value of the release film 20 can be adjusted, for example, by the type and amount of antistatic agent contained in the first antistatic layer 23. Generally, the more antistatic agent contained in the first antistatic layer 23, the better the conductivity of the first antistatic layer 23, and therefore the lower the surface resistance value of the release film 20 tends to be. The surface resistance value of the release film 20 is the surface resistance value on the side of the first antistatic layer 23 of the release film 20, and can be measured by the method described in the examples below.

[0029] Since the surface resistance value of the release film 20 is within the above range, even when removing one optical laminate 1 at a time from a superimposed body of multiple optical laminates 1, it is possible to suppress the simultaneous removal of two or more optical laminates 1.

[0030] (Surface protective film 30) The optical laminate 1 may have a surface protection film 30. The surface protection film 30 is used to cover and protect the surface of the polarizing plate 10. In the optical laminate 1, it is peelably bonded to the surface of the polarizing plate 10.

[0031] The surface protective film 30 may have an in-plane phase difference value of a size described later. When the surface protective film 30 has an in-plane phase difference, it is preferable that the slow axis of the surface protective film 30 and the absorption axis of the linearly polarized layer are substantially parallel or substantially orthogonal in the optical laminate 1. Here, substantially parallel means that the angle between the slow axis of the surface protective film 30 and the absorption axis of the linearly polarized layer is within 0°±10°, preferably within 0°±5°, and more preferably 0°. Substantially orthogonal means that the angle between the slow axis of the surface protective film 30 and the absorption axis of the linearly polarized layer is within 90°±10°, preferably within 90°±5°, and more preferably 90°.

[0032] The surface protection film 30 has, in order from the polarizer plate 10 side of the optical laminate 1, a second base film 31 and a second antistatic layer 33 containing an antistatic agent. As shown in Figure 1, the surface protection film 30 may further have a second adhesive layer 32 on the polarizer plate 10 side of the optical laminate 1, and the second adhesive layer 32 may be peelable from the polarizer plate 10. It is preferable that the second adhesive layer 32 and the second base film 31 are in direct contact. Although Figure 1 shows the case in which the surface protection film 30 has a second adhesive layer 32, if the second base film 31 is self-adhesive, the surface protection film 30 does not need to have a second adhesive layer 32. If the second base film 31 is self-adhesive, it is preferable that the second base film 31 and the polarizer plate 10 are in direct contact in the optical laminate 1.

[0033] The surface protection film 30 may further have a second antistatic layer 33 containing an antistatic agent on the side of the second base film 31 opposite to the second adhesive layer 32. It is preferable that the second base film 31 and the second antistatic layer 33 are in direct contact. Details of each layer will be described later.

[0034] The average in-plane phase difference value Re of the surface protective film 30 at a wavelength of 550 nm. A2 The average in-plane phase difference value Re A2The wavelength may be 1500 nm or more, 1800 nm or more, or 2000 nm or more. The above average in-plane phase difference value Re A2 This is usually 5000nm or less, but may also be 4000nm or less, or 3000nm or less.

[0035] The above average in-plane phase difference value Re of the surface protective film 30 A2 This can be adjusted, for example, by the in-plane phase difference value of the second base film 31. The in-plane phase difference value of the second base film 31 can be adjusted, for example, by the type of resin constituting the second base film 31, the stretching ratio, etc. The above average in-plane phase difference value Re A2 This is the average in-plane phase difference value Re of the release film described in the examples below. A1 It can be determined according to the method used to determine [the relevant factor].

[0036] The maximum value of the in-plane phase difference of the surface protective film 30 at a wavelength of 550 nm is Re ma2 The minimum value of the in-plane phase difference of the surface protective film 30 at a wavelength of 550 nm is Re mi2 In this case, the difference between the two is ΔRe2(=Re ma2 -Re mi2 ) may be 150 nm or less. The difference ΔRe2 may be 130 nm or less, 110 nm or less, 100 nm or less, 80 nm or less, or 60 nm or less. The difference ΔRe2 is usually 5 nm or more, and may be 10 nm or more. The above difference ΔRe2 may exceed 150 nm.

[0037] The above-mentioned difference ΔRe2 of the surface protective film 30 can be adjusted by the method of forming the second antistatic layer 33 on the second base film 31, etc. For example, as will be described later, it can be adjusted by the drying conditions of the coating layer applied on the second base film 31 to form the second antistatic layer 33. The above-mentioned difference ΔRe2 can be determined in accordance with the method for determining the difference ΔRe1 for the release film described in the examples described later.

[0038] The surface protection film 30 included in the optical laminate 1 has a second antistatic layer 33 to suppress multiple removals of the optical laminate 1 when removing it from a superimposed structure of multiple optical laminates 1. In a surface protection film with an antistatic layer, the in-plane phase difference value of the surface protection film may not be uniform within the plane and may vary. When inspecting the polarizing plate 10, if the variation in the in-plane phase difference value within the plane of the surface protection film becomes large, unevenness in the phase difference may be visible when observing light transmission using crossed nicols with the optical laminate, making it difficult to properly inspect the polarizing plate for defects, etc. This phenomenon is particularly noticeable when the surface protection film 30 of the optical laminate 1 is placed between the linear polarization layer of an inspection polarizing plate arranged to be crossed nicols and the linear polarization layer of the optical laminate 1.

[0039] In contrast, even if the optical laminate 1 has a second antistatic layer 33, if the difference ΔRe2 of the surface protective film 30 is 150 nm or less, the amount of fluctuation in the in-plane phase difference value is small, and unevenness in the phase difference is difficult to see when observing light transmission with crossed nicols using the optical laminate 1. As a result, even if either the release film 20 or the surface protective film 30 of the optical laminate 1 is placed between the linear polarization layer of the polarizing plate for inspection and the linear polarization layer of the optical laminate 1, the polarizing plate 10 can be inspected by observing light transmission with crossed nicols using the optical laminate 1, thus providing an optical laminate 1 with even greater inspection capabilities.

[0040] The surface resistance of surface protective film 30 at a temperature of 23°C and a relative humidity of 55%RH is 1.0 × 10⁻⁶. 8 Ω / □ or more 1.0×10 11 It is preferable that the surface resistance is Ω / □ or less. The above surface resistance value of the surface protective film 30 is 5.0 × 10 8 It may be greater than or equal to Ω / □, and 1.0 × 10 9 It may be greater than or equal to Ω / □, and also 5.0 × 10 10 It may be less than or equal to Ω / □, and 1.0 × 10 10 It may be less than or equal to Ω / □, and 5.0 × 10 9 It may be less than or equal to Ω / □.

[0041] The surface resistance value of the surface protection film 30 can be adjusted, for example, by the type and amount of antistatic agent contained in the second antistatic layer 33. Generally, the more antistatic agent contained in the second antistatic layer 33, the better the conductivity of the second antistatic layer 33, and therefore the lower the surface resistance value of the surface protection film 30 tends to be. The surface resistance value of the surface protection film 30 is the surface resistance value on the second antistatic layer 33 side of the surface protection film 30, and can be measured by the method described in the examples described later.

[0042] Since the surface resistance value of the surface protective film 30 is within the above range, even when removing one optical laminate 1 at a time from a superimposed body of multiple optical laminates 1, it becomes easier to suppress the simultaneous removal of two or more optical laminates 1.

[0043] The peeling force of the surface protective film 30 to the polarizing plate 10 at a temperature of 23°C and a relative humidity of 55% is preferably 0.01 N / 25 mm or more, may be 0.03 N / 25 mm or more, may be 0.08 N / 25 mm or more, and preferably 0.5 N / 25 mm or less, may be 0.4 N / 25 mm or less, or may be 0.3 N / 25 mm or less.

[0044] The above peeling force can be measured by the following procedure: The release film 20 is peeled off from an optical laminate 1 including a surface protective film, which has been cut into a rectangle of 150 mm x 25 mm, and the alkali-free glass substrate (thickness 0.7 mm, Corning "Eagle") is attached to the first adhesive layer 11. The test specimen is prepared by laminating it to "XG". This test specimen is exposed to a heated and pressurized environment by being placed in an autoclave with an internal temperature of 50°C and an internal pressure of 490.3kPa (gauge pressure) for 20 minutes, and then stored for 24 hours in an atmosphere of 23°C and 55% RH relative humidity to be prepared as an evaluation sample. For this evaluation sample, a peel test is performed in accordance with JIS K6854-2:1999 "Adhesives - Test methods for peel strength - Part 2: 180° peel" using a peeling device (Shimadzu Corporation "Autograph AGS-50NX") to peel the surface protective film 180° at a moving speed of 300 mm / min, and the peel strength is measured.

[0045] (Method for manufacturing optical laminate 1) The optical laminate 1 can be manufactured by laminating each layer so that it has the layer structure of the optical laminate 1 described above. For example, the optical laminate 1 can be manufactured by laminating a polarizing plate 10, a first adhesive layer 11, a release film 20, and, if necessary, a surface protection film 30. The optical laminate 1 may also be obtained, for example, by laminating a polarizing plate 10, or a laminate in which a surface protection film 30 and a polarizing plate 10 are laminated, onto a laminate in which the first adhesive layer 11 is laminated on the release treatment layer 22 side of the release film 20. Alternatively, the optical laminate 1 may be obtained by laminating a laminate of a first base film 21 and a release treatment layer 22 with a polarizing plate 10 via the first adhesive layer 11, and then forming a first antistatic layer 23 on the side of the first base film 21 opposite to the release treatment layer 22 side.

[0046] In the method for manufacturing the optical laminate 1, it is preferable to include the steps of applying a coating liquid containing an antistatic agent to a first base film 21 to form a first coating layer, and drying the first coating layer to form a first antistatic layer 23 of the release film 20. Applying the coating liquid to the first base film 21 makes it easier to uniformly distribute the antistatic agent on the first base film 21. The coating liquid preferably contains an antistatic agent, which will be described later, and a solvent such as water or an organic solvent.

[0047] A release treatment layer 22 may be formed on the first base film 21 that forms the first coating layer. Alternatively, a release treatment layer 22 may be formed on the first base film 21 on which the first antistatic layer 23 is formed. As described above, a release treatment layer 22, a first adhesive layer 11, and a polarizing plate 10 may be laminated on the first base film 21 that forms the first coating layer.

[0048] From the viewpoint of reducing variations in the in-plane phase difference of the release film and keeping it within the range of the above-mentioned difference ΔRe1, the temperature at which the first coating layer formed by applying the coating liquid is dried is preferably 60°C or lower, may be 50°C or lower, may be 40°C or lower, is usually 5°C or higher, preferably 10°C or higher, and more preferably 15°C or higher. The drying time for the first coating layer can be set according to the drying temperature, the amount and type of solvent contained in the coating layer, etc. For example, it can be 1 minute or more, may be 5 minutes or more, may be 10 minutes or more, is usually 100 minutes or less, may be 60 minutes or less, or may be 30 minutes or less.

[0049] As described above, the release film 20 has an average in-plane phase difference value Re at a wavelength of 550 nm. A1 The difference is 1000 nm or more. In such a release film 20, the first base film 21 is usually a highly stretched film, so when the first coating layer is heated and dried to form the first antistatic layer 23, it is thought that unevenness in the phase difference occurs due to the relaxation of the stretch of the first base film 21. In the manufacturing method of the optical laminate 1 of this embodiment, when forming the first antistatic layer 23, the drying temperature of the first coating layer is set to 60°C or less, so it is possible to suppress the relaxation of the stretch of the first base film 21, and it is presumed that the above-mentioned difference ΔRe1 of the release film 20 can be reduced to, for example, 150 nm or less.

[0050] The method for manufacturing the optical laminate 1 may include the steps of applying a coating liquid containing an antistatic agent to the second base film 31 to form a second coating layer, and drying the second coating layer to form a second antistatic layer 33 of the surface protective film 30. Applying the coating liquid to the second base film 31 makes it easier to uniformly distribute the antistatic agent on the second base film 31. The coating liquid may contain an antistatic agent, as described later, and a solvent such as water or an organic solvent.

[0051] A second adhesive layer 32 may be formed on the second base film 31 that forms the second coating layer. Alternatively, the second adhesive layer 32 may be formed on the second base film 31 on which the second antistatic layer 33 is formed. The second base film 31 that forms the second coating layer may have a polarizing plate 10 laminated on it, or the second adhesive layer and the polarizing plate 10 may be laminated in order from the second base film 31 side.

[0052] In particular, from the viewpoint of reducing variations in the in-plane phase difference of the surface protective film 30 and making the above-mentioned ΔRe2 150 nm or less, the temperature when applying and drying the coating liquid is preferably 60°C or less, may be 50°C or less, may be 40°C or less, is usually 5°C or more, is preferably 10°C or more, and is more preferably 15°C or more. The drying time of the second coating layer can be set according to the drying temperature, the amount and type of solvent contained in the coating layer, etc. For example, it can be 1 minute or more, may be 5 minutes or more, may be 10 minutes or more, is usually 100 minutes or less, may be 60 minutes or less, or may be 30 minutes or less.

[0053] The average in-plane phase difference value Re of the surface protective film 30 at a wavelength of 550 nm. A2When the wavelength is 1000 nm or greater, the second base film 31 is usually a highly stretched film. Therefore, when the second coating layer is heated and dried to form the second antistatic layer 33, it is thought that unevenness in the phase difference occurs due to the relaxation of the stretch of the second base film 31. In the manufacturing method of the optical laminate 1 of this embodiment, since the drying temperature of the second coating layer is set to 60°C or less when forming the second antistatic layer 33, it is possible to suppress the relaxation of the stretch of the second base film 31, and it is presumed that the above-mentioned difference ΔRe2 of the surface protective film 30 can be reduced to, for example, 150 nm or less.

[0054] [Embodiment 2] (Optical laminate 2) Figure 3 is a schematic cross-sectional view showing an optical laminate according to one embodiment of the present invention. Figure 4 is a schematic cross-sectional view showing an example of a cross-nicol inspection method for the optical laminate shown in Figure 3.

[0055] As shown in Figure 3, the optical laminate 2 is constructed by laminating a first adhesive layer 11, a polarizing plate 10 including a linear polarizing layer, and a surface protective film 50 that can be peeled off from the polarizing plate 10 in that order. In the optical laminate 2 shown in Figure 3, the first adhesive layer 11 and the polarizing plate 10 are in direct contact, and the polarizing plate 10 and the surface protective film 50 are in direct contact. The polarizing plate 10 and the first adhesive layer 11 included in the optical laminate 2 can be those described above.

[0056] The optical laminate 2 may further have a release film 40 on the side of the first adhesive layer 11 opposite to the polarizing plate 10, which can be peeled off from the first adhesive layer 11. The polarizing plate 10 of the optical laminate 2 can be incorporated into a display device as described in the previous embodiment.

[0057] (Surface protective film 50) The optical laminate 2 has a surface protection film 50. The surface protection film 50 is used to cover and protect the surface of the polarizing plate 10. In the optical laminate 2, it is peelably bonded to the surface of the polarizing plate 10. The surface protection film 50 has an in-plane phase difference value of a size described later, and in the optical laminate 2, the slow phase axis of the surface protection film 50 and the absorption axis of the linear polarizing layer are substantially parallel or substantially orthogonal. The angle between the slow phase axis and the absorption axis in the cases of substantially parallel and substantially orthogonal is as described in the previous embodiment.

[0058] The surface protection film 50 has, in order from the polarizer plate 10 side of the optical laminate 2, a second base film 51 and a second antistatic layer 53 containing an antistatic agent. As shown in Figure 3, the surface protection film 50 may further have a second adhesive layer 52 on the polarizer plate 10 side of the optical laminate 1, and the second adhesive layer 52 may be peelable from the polarizer plate 10. It is preferable that the second adhesive layer 52 and the second base film 51 are in direct contact. It is also preferable that the second base film 51 and the second antistatic layer 53 are in direct contact. Figure 3 shows the case where the surface protection film 50 has a second adhesive layer 52, but if the second base film 51 is self-adhesive, the surface protection film 50 does not need to have a second adhesive layer 52. If the second base film 51 is self-adhesive, it is preferable that the second base film 51 and the polarizer plate 10 are in direct contact in the optical laminate 2.

[0059] The average in-plane phase difference value Re of surface protective film 50 at a wavelength of 550 nm. A2 It is 1000 nm or more. The above average in-plane phase difference value Re A2 The wavelength may be 1500 nm or more, 1800 nm or more, or 2000 nm or more. The above average in-plane phase difference value Re A2 This is usually 5000nm or less, but may also be 4000nm or less, or 3000nm or less. The above average in-plane phase difference value Re of the surface protective film 50 A2This can be adjusted and determined by the method described in the previous embodiment.

[0060] The maximum value of the in-plane phase difference of the surface protective film 50 at a wavelength of 550 nm is Re ma2 The minimum in-plane phase difference value of the surface protective film 50 at a wavelength of 550 nm is set to Re mi2 In this case, the difference between the two is ΔRe2(=Re ma2 -Re mi2 ) is 150 nm or less. The difference ΔRe2 may be 130 nm or less, 110 nm or less, 100 nm or less, 80 nm or less, or 60 nm or less. The difference ΔRe2 is usually 5 nm or more, may be 10 nm or more, or 20 nm or more. The above difference ΔRe2 of the surface protective film 50 can be adjusted and determined by the method described in the previous embodiment.

[0061] The surface protection film 50 included in the optical laminate 2 has a second antistatic layer 53 to suppress multiple layers, etc. In a surface protection film with an antistatic layer, the in-plane phase difference value of the surface protection film may not be uniform within the plane and may vary. Inspection of the polarizing plate 10 may be performed by light transmission observation using crossed nicols with the optical laminate 2. In this case, if the variation in the in-plane phase difference value within the plane of the surface protection film becomes large, unevenness in the phase difference will be visible in light transmission observation using crossed nicols with the optical laminate including the polarizing plate and the surface protection film, making it difficult to properly inspect the polarizing plate for defects, etc. This phenomenon is particularly noticeable when the surface protection film 50 of the optical laminate 2 is placed between the linear polarization layer of the inspection polarizing plate 60, which is arranged to be crossed nicols, and the linear polarization layer of the optical laminate 2, as shown in Figure 4. The arrows in Figure 4 indicate the direction in which light from the light source 61 is observed when inspecting the polarizing plate 10.

[0062] In contrast, even though the optical laminate 2 has a second antistatic layer 53, the difference ΔRe2 of the surface protective film 50 is within the above range, so the amount of fluctuation in the in-plane phase difference value is small, and unevenness in the phase difference is difficult to see when observing light transmission with crossed nicols using the optical laminate 2. Therefore, since the polarizer plate 10 can be inspected by observing light transmission with crossed nicols using the optical laminate 2, the optical laminate 2 has excellent inspection properties.

[0063] The surface resistance value of the surface protection film 50 at a temperature of 23°C and a relative humidity of 55%RH can be within the range of the surface resistance value of the surface protection film described in the previous embodiment. By setting the surface resistance value of the surface protection film 50 within the above range, it becomes easier to suppress the multiple layers of the optical laminate.

[0064] The peeling force of the surface protective film 50 on the polarizing plate 10 at a temperature of 23°C and a relative humidity of 55% can be within the range of the surface protective film described in the previous embodiment.

[0065] (Release film 40) The optical laminate 2 may have a release film 40. The release film 40 is used to cover and protect the first adhesive layer 11. In the optical laminate 2, it is laminated peelably on the first adhesive layer 11. The release film 40 may have an in-plane phase difference, as will be described later. When the release film 40 has an in-plane phase difference, it is preferable that the slow axis of the release film 40 and the absorption axis of the linearly polarized layer are substantially parallel or substantially orthogonal in the optical laminate 2. The angle between the slow axis and the absorption axis when they are substantially parallel and substantially orthogonal is as described in the previous embodiment.

[0066] As shown in Figure 3, the release film 40 has a release treatment layer 42 and a first base film 41 in that order, starting from the side of the first adhesive layer 11 of the optical laminate 2. It is preferable that the release treatment layer 42 and the first base film 41 are in direct contact.

[0067] The release film 40 may further have a first antistatic layer 43 containing an antistatic agent on the side of the first base film 41 opposite to the release treatment layer 42. It is preferable that the first base film 41 and the first antistatic layer 43 are in direct contact.

[0068] The average in-plane phase difference value Re of the release film 40 at a wavelength of 550 nm. A1 It is 1000 nm or more. The above average in-plane phase difference value Re A1 The wavelength may be 1500 nm or more, 1800 nm or more, or 2000 nm or more. The above average in-plane phase difference value Re A1 This is usually 5000 nm or less, but may also be 4000 nm or less, or 3000 nm or less. The above average in-plane phase difference value Re of the release film 40 A1 This can be adjusted and determined by the method described in the previous embodiment.

[0069] The maximum value of the in-plane phase difference of the release film 40 at a wavelength of 550 nm is Re ma1 The minimum value of the in-plane phase difference of the release film 40 at a wavelength of 550 nm is set to Re mi1 In this case, the difference between the two is ΔRe1(=Re ma1 -Re mi1 ) is 150 nm or less. The difference ΔRe1 may be 130 nm or less, 110 nm or less, 100 nm or less, 80 nm or less, or 60 nm or less. The difference ΔRe1 is usually 5 nm or more, may be 10 nm or more, or 20 nm or more. The above difference ΔRe1 may exceed 150 nm. The above difference ΔRe1 of the release film 40 can be adjusted and determined by the method described in the previous embodiment.

[0070] The release film 40 included in the optical laminate 2 has a first antistatic layer 43 to suppress multiple layers, etc. In release films with an antistatic layer, the in-plane phase difference value of the release film may not be uniform in the plane and may vary. When inspecting the polarizing plate 10, the release film 40 of the optical laminate 2 may be placed in a crossed nicol formed between the linear polarization layer of the inspection polarizing plate and the linear polarization layer of the optical laminate 2. In this case, if the variation in the in-plane phase difference value of the release film becomes large, unevenness in the phase difference will be visible when observing light transmission using the optical laminate in a crossed nicol, making it difficult to properly inspect the polarizing plate for defects, etc. This phenomenon is particularly noticeable when the release film 40 of the optical laminate 2 is placed between the linear polarization layer of the inspection polarizing plate and the linear polarization layer of the optical laminate 2, which are arranged to form a crossed nicol.

[0071] In contrast, even if the optical laminate 2 has a first antistatic layer 43, if the difference ΔRe1 of the release film 40 is 150 nm or less, the amount of fluctuation in the in-plane phase difference value is small, and unevenness in the phase difference is difficult to see when observing light transmission with crossed nicols using the optical laminate 2. As a result, even if either the surface protective film 50 or the release film 40 of the optical laminate 2 is placed between the linear polarization layer of the polarizing plate for inspection and the linear polarization layer of the optical laminate 1, the polarizing plate 10 can be inspected by observing light transmission with crossed nicols using the optical laminate 2, thus providing an optical laminate 2 with even greater inspection capabilities.

[0072] The surface resistance value of the release film 40 at a temperature of 23°C and a relative humidity of 55%RH can be within the range of the surface resistance value of the release film described in the previous embodiment. By setting the surface resistance value of the release film 40 within the above range, it becomes easier to further suppress the formation of multiple layers of the optical laminate.

[0073] (Method for manufacturing optical laminate 2) The optical laminate 2 can be manufactured by laminating each layer so that it has the layer structure of the optical laminate 2 described above. For example, the optical laminate 2 can be manufactured by laminating the first adhesive layer 11, polarizing plate 10, surface protection film 50, and, if necessary, release film 40. The optical laminate 2 may also be obtained by laminating the first adhesive layer 11, or a laminate in which the first adhesive layer 11 is laminated on the release treatment layer 42 side of the release film 40, onto a laminate in which the surface protection film 50 and the polarizing plate 10 are laminated. Alternatively, the optical laminate 2 may be obtained by first obtaining a laminate in which the second base film 51 and the polarizing plate 10 are laminated, or by first obtaining a laminate in which the second base film 51, the second adhesive layer 52, and the polarizing plate 10 are laminated in this order, and then forming the second antistatic layer 53 on the side of the second base film 51 opposite to the polarizing plate 10.

[0074] In the method for manufacturing the optical laminate 2, the method for forming a surface protective film 50 by forming a second antistatic layer 53 on a second base film 51, and the method for forming a release film 40 by forming a first antistatic layer 43 on a first base film 41, are the methods described in the previous embodiment. In each method, the temperature at which the coating liquid is dried is preferably within the range of temperatures described in the previous embodiment, from the viewpoint of reducing variations in in-plane phase difference.

[0075] The layers and other components that make up the optical laminate described above will be explained in more detail below.

[0076] (First base film) The first base film included in the release film can be a film formed from a thermoplastic resin, and is usually a stretched film that has undergone a stretching treatment. Examples of thermoplastic resins that form the first base film include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having cyclo and norbornene structures (also called norbornene resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins; cellulose resins such as triacetylcellulose; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamides; and polyimide resins. The first base film is preferably a polyester resin film, and more preferably a stretched polyester resin film that has undergone a stretching treatment. "(meth)acrylic" means at least one selected from acrylic and methacrylic.

[0077] The average in-plane phase difference value of the first substrate film at a wavelength of 550 nm is usually 1000 nm or more, but may be 1500 nm or more, 1800 nm or more, or 2000 nm or more, and is usually 5000 nm or less, but may be 4000 nm or less, or 3000 nm or less. The above average in-plane phase difference value can be determined in accordance with the method for determining the average in-plane phase difference value ReA1 of the release film described in the examples below.

[0078] The thickness of the first base film is, for example, 5 μm or more, may be 10 μm or more, may be 50 μm or more, may be 70 μm or more, and may be, for example, 300 μm or less, may be 200 μm or less, may be 150 μm or less, may be 120 μm or less, or may be 100 μm or less.

[0079] (Release layer) The release layer contained in the release film is a layer formed by applying a release treatment to one surface of the first base film. The release layer is, for example, a coating layer formed by coating the surface of the first base film with a release agent composition containing known release agents such as fluorine compounds, silicone compounds, long-chain alkyl compounds, and fatty acid amide compounds.

[0080] The thickness of the release layer can be 10 nm to 2000 nm, but is preferably 10 nm to 1000 nm, and more preferably 10 nm to 500 nm.

[0081] (First antistatic layer) The first antistatic layer, which may be included in the release film, contains an antistatic agent. Known antistatic agents can be used, including, for example, conductive polymers; conductive fine particles such as metal fine particles, metal oxide fine particles, or fine particles coated with metal; ionic conductive compositions consisting of an electrolyte salt and an organopolysiloxane; ionic compounds; surfactants (cationic, anionic, and amphoteric surfactants); and at least one of hydrolyzable organosilicon compounds and their condensed polymers. The first antistatic layer may contain one or more of the above-mentioned antistatic agents. The inclusion of an antistatic agent in the antistatic layer reduces its electrical resistance, thereby imparting antistatic properties to the release film and, consequently, the optical laminate.

[0082] Examples of conductive polymers include polyacetylene, polyphenylene bonded at the para or meta position, polymers in which phenyl groups are linked via divalent groups (for example, polyphenylene vinylene with phenyl groups linked via -CH=CH-, polyphenylene sulfide with phenyl groups linked via -S-, and polyphenylene oxide with phenyl groups linked via -O-), and polymers in which the five-membered ring contains one element other than C and H and is linked at the 2nd and 5th positions. (For example, polypyrroles have five-membered rings containing NH linked at positions 2 and 5; polythiophenes have five-membered rings containing S linked at positions 2 and 5; polyfurans have five-membered rings containing O linked at positions 2 and 5; polyselenophenes have five-membered rings containing Se linked at positions 2 and 5; and polyterlofenes have five-membered rings containing Te linked at positions 2 and 5.) Polymers obtained by polymerizing aromatic amines (for example, polyaniline and polyaminopyrene) and polystyrene sulfonic acid are examples.

[0083] Examples of conductive fine particles include silver powder, copper powder, nickel powder, zinc oxide (ZnO), tin oxide (SnO2), antimond-doped tin oxide (ATO), and tin-doped indium oxide (ITO).

[0084] Examples of ionic conductive compositions include electrolyte salts and organopolysiloxanes represented by the following formula. [ka] [In the formula, R 11 R is a monovalent organic group. 12 ~R 14 is an alkylene group, R 15 represents hydrogen or a monovalent organic group. m is an integer between 0 and 100, and n is an integer between 1 and 100. -(-Si(R 11 R 11 )O-)-unit and -(-Si(R 11 R 12 The order of the )O-)- units is arbitrary. a and b are each integers between 0 and 100, and cannot be 0 at the same time. -(-R 13 O-)- and -(-R 14 The order of the O-)- sequences is arbitrary.

[0085] Examples of electrolyte salts include those in which the cation is a metal cation belonging to Group I or Group II of the periodic table. Examples of cations include lithium, sodium, potassium, magnesium, calcium, and barium.

[0086] Ionic compounds are, for example, compounds having an inorganic cation or an organic cation and an inorganic anion or an organic anion.

[0087] Examples of inorganic cations include lithium cations [Li + ], sodium cation [Na + ), potassium cation [K + Alkali metal ions such as [Be] and beryllium cations [Be] 2+ ], magnesium cation [Mg 2+ ], calcium cation [Ca 2+ Examples include alkaline earth metal ions such as [ ].

[0088] Examples of organic cations include imidazolium cations, pyridinium cations, pyrrolidinium cations, ammonium cations, sulfonium cations, phosphonium cations, and piperidinium cations.

[0089] Examples of inorganic anions include the chloride anion [Cl - ], bromide anion [Br - ], Yodid Anion [I - ], tetrachloroaluminate anion [AlCl4 - ], heptachlorodialuminate anion [Al2Cl7 - ], tetrafluoroborate anion [BF4 -〕, hexafluorophosphate anion [PF6 - 〕, perchlorate anion [ClO4 - 〕, nitrate anion [NO3 - 〕, hexafluoroarsenate anion [AsF6 - 〕, hexafluoroantimonate anion [SbF6 - 〕, hexafluoroniobate anion [NbF6 - 〕, hexafluorotantalate anion [TaF6 - 〕, dicyanamide anion [(CN)2N - 〕, etc. can be mentioned.

[0090] Examples of organic anions include acetate anion [CH3COO - 〕, trifluoroacetate anion [CF3COO - 〕, methanesulfonate anion [CH3SO3 - 〕, trifluoromethanesulfonate anion [CF3SO3 - 〕, p-toluenesulfonate anion [p-CH3C6H4SO3 - 〕, bis(fluorosulfonyl)imide anion [(FSO2)2N - 〕, bis(trifluoromethanesulfonyl)imide anion [(CF3SO2)2N - 〕, tris(trifluoromethanesulfonyl)methanide anion [(CF3SO2)3C - 〕, dimethylphosphinate anion [(CH3)2POO - 〕, (poly)hydrofluorofluoride anion [F(HF)n - 〕 (n is about 1 to 3), thiocyanate anion [SCN - 〕, perfluorobutanesulfonate anion [C4F9SO3 - 〕, bis(pentafluoroethanesulfonyl)imide anion [(C2F5SO2)2N - 〕, perfluorobutanoate anion [C3F7COO - 〕, (trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imide anion [(CF3SO2)(CF3CO)N -], perfluoropropane-1,3-disulfonate anion [ - O3S(CF2)3SO3 - ], carbonate anion [CO3 2- Examples include:

[0091] Specific examples of ionic compounds can be appropriately selected from the above combinations of cationic and anionic components. Examples of ionic compounds having organic cations, classified by the structure of the organic cation, are as follows:

[0092] Pyridinium salts: N-hexylpyridinium hexafluorophosphate, N-octylpyridinium hexafluorophosphate, N-octyl-4-methylpyridinium hexafluorophosphate, N-butyl-4-methyllupyridinium hexafluorophosphate, N-decylpyridinium bis(fluorosulfonyl)imide, N-dodecylpyridinium bis(fluorosulfonyl)imide, N-tetradecylpyridinium bis(fluorosulfonyl)imide, N-Hexadecylpyridinium bis(fluorosulfonyl)imide, N-dodecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-tetradecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-Hexadecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-benzyl-2-methylpyridinium bis(fluorosulfonyl)imide, N-benzyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-Hexylpyridinium bis(trifluoromethanesulfonyl)imide N-octylpyridinium bis(trifluoromethanesulfonyl)imide, N-octyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide, N-butyl-4-methyllupyridinium bis(trifluoromethanesulfonyl)imide.

[0093] Imidazolium salt: 1-Ethyl-3-methylimidazolium hexafluorophosphate, 1-Ethyl-3-methylimidazolium p-toluenesulfonate, 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide 1-Butyl-3-methylimidazolium methanesulfonate, 1-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide.

[0094] Pyrrolidinium salts: N-butyl-N-methylpyrrolidinium hexafluorophosphate, N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

[0095] Quaternary ammonium salts: Tetrabutylammonium hexafluorophosphate, Tetrabutylammonium p-toluenesulfonate, (2-hydroxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide (2-hydroxyethyl)trimethylammonium dimethylphosphine.

[0096] Furthermore, examples of ionic compounds containing inorganic cations include the following: Lithium bromide, Lithium iodide, Lithium tetrafluoroborate, Lithium hexafluorophosphate, Lithium thiocyanate, Lithium perchlorate, Lithium trifluoromethanesulfonate, Lithium bis(fluorosulfonyl)imide, Lithium bis(trifluoromethanesulfonyl)imide, Lithium bis(pentafluoroethanesulfonyl)imide, Lithium tris(trifluoromethanesulfonyl)methanide, Lithium p-toluenesulfonate, Sodium hexafluorophosphate, Sodium bis(fluorosulfonyl)imide, Sodium bis(trifluoromethanesulfonyl)imide, Sodium p-toluenesulfonate, Potassium hexafluorophosphate, Potassium bis(fluorosulfonyl)imide, Potassium bis(trifluoromethanesulfonyl)imide, Potassium p-toluenesulfonate.

[0097] These ionic compounds may be used individually or in combination of two or more.

[0098] Examples of surfactants include hydrocarbon-based surfactants, fluorine-based surfactants, and silicone-based surfactants.

[0099] Hydrolyzable organosilicon compounds are compounds in which a non-hydrolyzable organic group and a hydrolyzable organic or inorganic group are bonded to a silicon atom, or compounds in which a hydrolyzable organic group is bonded to a silicon atom. Here, the organic group may have a carbon atom bonded to it, or another atom may be bonded to it. Hydrolyzable organosilicon compounds can be specifically represented by the following formula. Si(T1 ) q (T 2 ) 4-q [In the formula, T 1 represents a hydrogen atom or a non-hydrolyzable organic group, T 2 [where represents a hydrolyzable group, and q represents an integer from 0 to 3.]

[0100] In the above formula, T 1 Typical examples of non-hydrolyzable organic groups represented by include alkyl groups having approximately 1 to 4 carbon atoms, alkenyl groups having approximately 2 to 4 carbon atoms, and aryl groups such as phenyl groups. 2 Examples of hydrolyzable groups represented by the above formula include alkoxy groups having about 1 to 5 carbon atoms, such as methoxy groups and ethoxy groups; acyloxy groups, such as acetoxy groups and propionyloxy groups; halogen atoms, such as chlorine atoms and bromine atoms; and substituted silylamino groups, such as trimethylsilylamino groups. Hydrolyzable organosilicon compounds may also be alkoxysilane compounds, halogenated silane compounds, acyloxysilane compounds, silazane compounds, etc. These hydrolyzable organosilicon compounds are represented by the T in the above formula. 1 or T 2 As part of the compound, it may have substituents such as aryl groups, vinyl groups, allyl groups, (meth)acryloyloxy groups, epoxy groups, amino groups, mercapto groups, and fluoroalkyl groups. "(meth)acryloyl" means at least one selected from acryloyl and methacryloyl.

[0101] Specific examples of hydrolyzable organosilicon compounds include halogenated silane compounds such as methyltrichlorosilane; alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane; and silazane compounds such as hexamethyldisilazane. These can be used individually or in combination of two or more.

[0102] As the hydrolyzable organosilicon compound, hydrolysis products obtained by partially hydrolyzing the above-mentioned hydrolyzable organosilicon compound may be used. Alternatively, as the hydrolyzable organosilicon compound, a polymer obtained by condensing the above-mentioned hydrolysis products may be used as an oligomer or polymer. These hydrolysis products and polymers can be produced by adding an acid such as hydrochloric acid, phosphoric acid, acetic acid, or sulfuric acid, or a base such as sodium hydroxide or sodium acetate, to the hydrolyzable organosilicon compound.

[0103] As an antistatic agent, a condensed polymer obtained by hydrolyzing and polycondensing the above-mentioned hydrolyzable organosilicon compounds may be used. The hydrolysis of the above-mentioned hydrolyzable organosilicon compounds can be carried out by known methods. Specifically, the hydrolyzable organosilicon compound can be dissolved in a predetermined amount of organic solvent in an amount that requires a predetermined solid content concentration to form a homogeneous solution, and then hydrolyzed in the presence of a catalyst. If an organic solvent is not used, the hydrolyzable organosilicon compound can be added to a homogeneous solution of water and a catalyst in an amount that requires a predetermined solid content concentration, and then hydrolyzed. Generally, hydrolysis can be carried out by adding an amount of water required for the desired hydrolysis rate in the presence of an acid or alkali catalyst. As catalysts for hydrolysis, there are acids such as hydrochloric acid, phosphoric acid, sulfuric acid, and acetic acid, and basic hydroxide catalysts such as LiOH, NaOH, and KOH, and 0.01 to 10% by weight is used relative to the hydrolyzable organosilicon compound. The reaction temperature for hydrolysis can be as low as room temperature to 50°C, and the reaction time varies depending on the reaction temperature and the amount of catalyst, but is generally 1 to 24 hours. A condensed polymer of the hydrolyzable organosilicon compound is prepared by the above hydrolysis reaction. Furthermore, when a condensed polymer of a hydrolyzable organosilicon compound gels on a coated surface, it acquires a large number of silanol groups (Si-OH) containing hydroxyl groups on its surface, which is effective in exhibiting antistatic properties. Since the condensed polymer of a hydrolyzable organosilicon compound is prepared by hydrolysis, the terminal groups of the polymer contain OH groups, which is also effective in exhibiting antistatic properties.

[0104] Hydrolyzable organosilicon compounds and their condensed polymers may be used individually, or as a mixture of the hydrolyzable organosilicon compound and its condensate.

[0105] The first antistatic layer can be formed, for example, by applying a coating solution containing an antistatic agent to the surface of the first substrate film. The coating solution typically contains an antistatic agent, a solvent (including water), and, if necessary, a curable resin such as a (meth)acrylic compound that hardens upon irradiation with heat or active energy rays. The surface of the first substrate film may be subjected to surface activation treatments such as corona treatment, plasma treatment, primer treatment, or anchor coating treatment, if necessary. This improves the adhesion between the first antistatic layer and the first substrate film and improves the wettability of the coating solution to the first substrate film.

[0106] Solvents are used to adjust the concentration and viscosity of the coating solution, the film thickness of the coating layer, etc. The solvent used can be selected as appropriate, but examples include water; alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, isobutanol, and tert-butanol; alkoxy alcohols such as 2-ethoxyethanol, 2-butoxyethanol, 3-methoxypropanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ketoles such as diacetone alcohol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; and ethers such as dioxane and tetrahydrofuran. The amount of solvent used is selected as appropriate depending on the material, shape, coating method of the first substrate film, the desired thickness of the first antistatic layer, etc., but is usually about 20 to 100,000 parts by weight per 100 parts by weight of the total amount of antistatic agent.

[0107] Methods for applying a coating solution to the surface of the first substrate film include, for example, microgravure coating, roll coating, dipping coating, flow coating, spin coating, die coating, cast transfer, and spray coating.

[0108] The first antistatic layer is preferably formed by applying a coating liquid to the surface of the first substrate film and drying the resulting coating layer. The drying temperature is preferably 60°C or lower, as described above, from the viewpoint of reducing variations in the in-plane phase difference of the release film.

[0109] The thickness of the first antistatic layer can be between 10 nm and 1000 nm, but from the viewpoint of thinning the optical laminate, it is preferably 800 nm or less, but may also be 700 nm or less, 50 nm or more, or 100 nm or more. If the thickness of the first antistatic layer is less than 10 nm, the adhesion, antistatic properties, and strength may be insufficient, and if it exceeds 1000 nm, the adhesion and transparency may be insufficient, and defects such as cracking may occur.

[0110] (1st adhesive layer) The first adhesive layer is an adhesive layer formed using an adhesive composition. The adhesive composition or the reaction product of the adhesive composition exhibits adhesive properties by adhering itself to a substrate such as a metal layer, and is referred to as a pressure-sensitive adhesive. Furthermore, the adhesive layer formed using the active energy ray curable adhesive composition described later can have its degree of crosslinking and adhesive strength adjusted by irradiation with active energy rays.

[0111] As the adhesive composition, any conventionally known adhesive with excellent optical transparency can be used without particular limitation. For example, adhesive compositions containing base polymers such as acrylic polymers, urethane polymers, silicone polymers, and polyvinyl ethers can be used. The adhesive composition may also be an active energy ray curing adhesive composition or a thermosetting adhesive composition. Among these, an adhesive composition using an acrylic resin as the base polymer, which has excellent transparency, adhesive strength, re-peelability (reworkability), weather resistance, and heat resistance, is preferred. The adhesive layer is preferably composed of reaction products of an adhesive composition containing (meth)acrylic resin, a crosslinking agent, and a silane compound, and may contain other components.

[0112] The adhesive composition for forming the first adhesive layer may include, for example, a base polymer such as an acrylic polymer, urethane polymer, silicone polymer, or polyvinyl ether. The adhesive composition may also be an active energy ray curing adhesive or a thermosetting adhesive. Among these, an adhesive using (meth)acrylic resin as the base polymer, which has excellent transparency, adhesive strength, re-peelability (reworkability), weather resistance, and heat resistance, is preferred. The adhesive layer is preferably composed of a reaction product of an adhesive containing (meth)acrylic resin, a crosslinking agent, and a silane compound, and may also contain other components.

[0113] The first adhesive layer may be formed using an active energy ray curable adhesive. An active energy ray curable adhesive can be formed by blending an ultraviolet-curable compound such as a polyfunctional acrylate with the above-mentioned adhesive composition, forming a layer using this compound, and then curing it by irradiation with ultraviolet light, thereby forming a harder adhesive layer. Active energy ray curable adhesives have the property of curing when irradiated with energy rays such as ultraviolet light or electron beams. Because active energy ray curable adhesives are tacky even before irradiation with energy rays, they adhere closely to the substrate, and the adhesion strength can be adjusted by curing through irradiation with energy rays.

[0114] The thickness of the first adhesive layer is not particularly limited, but is preferably 5 μm or more, may be 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, and is usually 300 μm or less, may be 250 μm or less, 100 μm or less, or 50 μm or less.

[0115] (Linear polarized layer) The linear polarization layer contained in a polarizing plate has the property of transmitting linearly polarized light having a vibration plane perpendicular to the absorption axis when unpolarized light is incident on it. The linear polarization layer may be a polyvinyl alcohol-based resin film (hereinafter sometimes referred to as "PVA-based film") on which iodine is adsorbed and oriented, or it may be a film containing a liquid crystalline polarization layer formed by coating a base film with a composition containing a compound having absorption anisotropy and liquid crystalline properties. The compound having absorption anisotropy and liquid crystalline properties may be a mixture of a dye having absorption anisotropy and a compound having liquid crystalline properties, or it may be a dye having absorption anisotropy and liquid crystalline properties.

[0116] The linearly polarized layer is preferably a PVA-based film on which iodine is adsorbed and oriented. Examples of PVA-based films for the linearly polarized layer include polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which have been subjected to iodine dyeing and stretching treatments. If necessary, the PVA-based film on which iodine has been adsorbed and oriented by the dyeing treatment may be treated with an aqueous boric acid solution, followed by a washing step to wash off the aqueous boric acid solution. Known methods can be used for each step.

[0117] Polyvinyl alcohol-based resins (hereinafter sometimes referred to as "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 copolymers of vinyl acetate and other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups.

[0118] The degree of saponification of PVA resins is typically around 85-100 mol%, preferably 98 mol% or higher. PVA resins may be modified; for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of PVA resins is typically around 1,000-10,000, preferably 1,500-5,000. The degree of saponification and average degree of polymerization of PVA resins can be determined in accordance with JIS K 6726 (1994). If the average degree of polymerization is less than 1,000, it is difficult to obtain desirable polarization performance, and if it exceeds 10,000, film processability may be poor.

[0119] A method for manufacturing a linearly polarized film made of PVA may include the steps of preparing a base film, applying a resin solution such as a PVA resin onto the base film, and drying to remove the solvent to form a resin layer on the base film. A primer layer may be formed in advance on the surface of the base film on which the resin layer will be formed. As the base film, a film made of a resin material described later as a thermoplastic resin used to form the first protective film can be used. As the material for the primer layer, examples include a resin obtained by crosslinking a hydrophilic resin used in the linearly polarized film.

[0120] Next, the amount of solvent, such as water, in the resin layer is adjusted as needed. Then, the base film and the resin layer are uniaxially stretched, and subsequently, the resin layer is stained with iodine to adsorb and orient the iodine into the resin layer. Next, if necessary, the resin layer with the adsorbed and oriented iodine is treated with an aqueous boric acid solution, and then a washing step is performed to wash off the aqueous boric acid solution. This produces a PVA-based film in which the resin layer with the adsorbed and oriented iodine, i.e., the linearly polarized layer, is formed. Known methods can be used for each step.

[0121] The amount of boric acid in the boric acid-containing aqueous solution used to treat the PVA-based film or resin layer on which iodine is adsorbed and oriented is usually about 2 to 15 parts by mass per 100 parts by mass of water, and preferably 5 to 12 parts by mass. This boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by mass per 100 parts by mass of water, and preferably 5 to 12 parts by mass. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

[0122] Uniaxial stretching of the PVA film, as well as the base film and resin layer, may be performed before dyeing, during dyeing, or during the boric acid treatment after dyeing, or uniaxial stretching may be performed at each of these multiple stages. The PVA film, as well as the base film and resin layer, may be uniaxially stretched in the MD direction (film transport direction), in which case uniaxial stretching may be performed between rolls with different peripheral speeds, or uniaxial stretching may be performed using a heated roll. The PVA film, as well as the base film and resin layer, may also be uniaxially stretched in the TD direction (direction perpendicular to the film transport direction), in which case the so-called tenter method can be used. Furthermore, the stretching may be dry stretching performed in air, or wet stretching performed while the PVA film or resin layer is swollen with a solvent. In order to exhibit the performance of the linearly polarized 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, etc., 8 times or less is preferred.

[0123] A linearly polarized film produced using a manufacturing method that utilizes a base film can be obtained by laminating a protective layer and then peeling off the base film.

[0124] The thickness of the linearly polarizing layer, which is a PVA-based film, is preferably 1 μm or more, may be 2 μm or more, may be 5 μm or more, preferably 30 μm or less, more preferably 15 μm or less, may be 10 μm or less, or may be 8 μm or less.

[0125] A film containing a liquid crystalline polarizing layer includes a linear polarizing layer obtained by coating a base film with a composition containing a dye having liquid crystalline properties and absorption anisotropy, or a composition containing a dye having absorption anisotropy and a polymerizable liquid crystal. Examples of base films include films using resin materials described later as thermoplastic resins used to form a protective layer. Examples of films containing a liquid crystalline polarizing layer include the polarizing layer described in Japanese Patent Application Publication No. 2013-33249.

[0126] The total thickness of the base film and the linearly polarized layer formed as described above is preferably small, but if it is too small, the strength decreases and the processability tends to be poor. Therefore, it is usually 50 μm or less, preferably 30 μm or less, and more preferably 0.5 μm to 25 μm.

[0127] (protective layer) The protective layer that may be included in the polarizing plate may be laminated so as to be in direct contact with the linear polarizing layer, but it is preferable that it be laminated via a bonding layer. The protective layer is preferably a resin layer, and more preferably a resin film. Examples of resin films include films formed from thermoplastic resins that are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, stretchability, etc. Specific examples of thermoplastic resins include cellulose resins such as triacetylcellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamides; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having cyclo and norbornene structures (also called norbornene resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins; and mixtures thereof.

[0128] The protective layer may have anti-reflective properties, anti-glare properties, hard coat properties, etc. (Hereinafter, a protective film having such properties may be referred to as a "functional protective film"). If the protective layer is not a functional protective film, a surface functional layer such as an anti-reflective layer, anti-glare layer, or hard coat layer may be laminated on the linear polarization layer or the protective layer. The surface functional layer is preferably provided in direct contact with the protective layer. The surface functional layer is preferably provided on the side of the protective layer opposite to the linear polarization layer side and on the side of the polarizing plate opposite to the first adhesive layer side.

[0129] The protective layer is preferably 3 μm or thicker, more preferably 5 μm or thicker, and preferably 50 μm or less, and more preferably 30 μm or less.

[0130] (Bonding layer) Examples of bonding layers that the polarizing plate may have include an adhesive layer or a bonding agent layer. Examples of adhesive layers include an adhesive layer formed using the adhesive composition described in the first adhesive layer above. The thickness of the adhesive layer is not particularly limited, but is preferably 5 μm or more, may be 10 μm or more, may be 15 μm or more, may be 20 μm or more, may be 25 μm or more, and is usually 300 μm or less, may be 250 μm or less, may be 100 μm or less, or may be 50 μm or less.

[0131] The adhesive layer can be formed by curing the curable component in the adhesive composition. Examples of adhesive compositions for forming the adhesive layer include adhesives other than pressure-sensitive adhesives (tacks), such as water-based adhesives and active energy ray-curable adhesives.

[0132] Examples of water-based adhesives include adhesives in which polyvinyl alcohol resin is dissolved or dispersed in water. There are no particular limitations on the drying method when using water-based adhesives, but methods such as using a hot air dryer or an infrared dryer can be employed.

[0133] Examples of active energy ray curing adhesives include solvent-free active energy ray curing adhesives containing curable compounds that harden upon irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays. By using a solvent-free active energy ray curing adhesive, the adhesion between layers can be improved.

[0134] As an active energy ray curable adhesive, it is preferable to include either a cationic curable compound, a radical curable compound, or both, as these exhibit good adhesion. The active energy ray curable adhesive may further contain a cationic polymerization initiator, such as a photocationic polymerization initiator, or a radical polymerization initiator for initiating the curing reaction of the above-mentioned curable compound.

[0135] Examples of cationically polymerizable curable compounds include epoxy compounds such as alicyclic epoxy compounds having epoxy groups bonded to an alicyclic ring, polyfunctional aliphatic epoxy compounds having two or more epoxy groups but no aromatic ring, monofunctional epoxy groups having one epoxy group (excluding those included in alicyclic epoxy compounds), and polyfunctional aromatic epoxy compounds having two or more epoxy groups and an aromatic ring; oxetane compounds having one or more oxetane rings in the molecule; and combinations thereof.

[0136] 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 thereof.

[0137] Active energy ray curing adhesives may contain sensitizers, such as photosensitizers, as needed. Using sensitizers improves reactivity and further enhances the mechanical strength and adhesive strength of the adhesive layer. Known sensitizers can be appropriately applied. When sensitizers are included, the amount 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 curing adhesive.

[0138] Active energy ray curing adhesives may contain additives such as ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, antistatic agents, leveling agents, and solvents, as needed.

[0139] When using an active energy ray curing adhesive, the adhesive coating layer can be cured by irradiating it with active energy rays such as ultraviolet light, visible light, electron beams, or X-rays to form an adhesive layer. Ultraviolet light is preferred as the active energy ray, and in this case, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc., can be used as light sources.

[0140] The thickness of the adhesive layer is preferably 0.1 μm or more, may be 0.5 μm or more, and preferably 10 μm or less, and may be 5 μm or less.

[0141] (Second base film) The second base film included in the surface protection film can be a film formed from a thermoplastic resin, and is usually a stretched film that has undergone a stretching treatment. Examples of thermoplastic resins that form the first base film include those described as thermoplastic resins that form the first base film.

[0142] If the second base film is self-adhesive, the second base film may be formed from a self-adhesive film. A self-adhesive film is a film that adheres on its own without the need for means of adhesion such as a second adhesive layer, and is capable of maintaining that adhered state. A self-adhesive film can be formed using, for example, a polypropylene resin and a polyethylene resin.

[0143] The thickness of the second base film is, for example, 5 μm or more, may be 10 μm or more, 50 μm or more, 70 μm or more, or, for example, 300 μm or less, may be 200 μm or less, 150 μm or less, 120 μm or less, or 100 μm or less.

[0144] The average in-plane phase difference value of the second substrate film at a wavelength of 550 nm is usually 1000 nm or more, but may be 1500 nm or more, 1800 nm or more, 2000 nm or more, and is usually 5000 nm or less, but may be 4000 nm or less, or 3000 nm or less. The above average in-plane phase difference value is the average in-plane phase difference value Re of the release film described in the examples below. A1 It can be determined according to the method used to determine [the relevant factor].

[0145] (Second adhesive layer) The second adhesive layer contained in the surface protective film is an adhesive layer formed using an adhesive composition. Examples of adhesive compositions include those described as adhesive compositions for forming the first adhesive layer.

[0146] The thickness of the second adhesive layer is not particularly limited, but is preferably 5 μm or more, may be 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, and is usually 300 μm or less, may be 250 μm or less, 100 μm or less, or 50 μm or less.

[0147] (Second antistatic layer) The second antistatic layer, which may be included in the surface protective film, contains an antistatic agent. Examples of antistatic agents include those used to form the first antistatic layer. The second antistatic layer may contain one or more of the above-mentioned antistatic agents. By including an antistatic agent in the antistatic layer, the electrical resistance of the antistatic layer is reduced, thereby imparting antistatic performance to the surface protective film and, consequently, to the optical laminate.

[0148] The second antistatic layer can be formed in the same manner as the first antistatic layer, except, for example, that the second base film is used instead of the first base film. The second antistatic layer is preferably formed by applying a coating liquid to the surface of the second base film and drying the resulting coating layer. The drying temperature is preferably 60°C or lower, as described above, from the viewpoint of reducing variations in the in-plane phase difference of the surface protective film.

[0149] The thickness of the second antistatic layer can be between 10 nm and 1000 nm, but from the viewpoint of thinning the optical laminate, it is preferably 800 nm or less, but may also be 700 nm or less, 50 nm or more, or 100 nm or more. If the thickness of the second antistatic layer is less than 10 nm, the adhesion, antistatic properties, and strength may be insufficient, and if it exceeds 1000 nm, the adhesion and transparency may be insufficient, and defects such as cracking may occur. [Examples]

[0150] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "parts" in the examples and comparative examples refer to mass percent and parts by mass.

[0151] [Measuring Phase Difference Values] For the release films used in the examples and comparative examples, the in-plane phase difference values ​​at a wavelength of 550 nm were measured using a phase difference measuring device (KOBRA-WPR, manufactured by Oji Instruments Co., Ltd.) in the following procedure: The in-plane phase difference values ​​were measured for a 300 mm square area of ​​the release film, and the measured in-plane phase difference values ​​were averaged to obtain the average in-plane phase difference value Re A1 The maximum value Re of the measured in-plane phase difference is calculated. ma1 and minimum value Re mi1 The difference between ΔRe1(=Re ma1 -Re mi1 The result was calculated. The results are shown in Table 1.

[0152] [Measurement of surface resistance] The surface resistance values ​​of the release films and surface protection films used in the examples and comparative examples were measured using the "MCP-HT450" manufactured by Mitsubishi Chemical Analytec Co., Ltd. Each surface resistance value was measured under conditions of 23°C and 55% RH relative humidity on the surface of the first antistatic layer of the release film and the surface of the second antistatic layer of the surface protection film. The results are shown in Table 1.

[0153] [Example 1] (Preparation of release film (1)) A polyethylene terephthalate (PET) film (manufactured by Lintec Corporation: product name "PLR-382190") with a release treatment applied to one side to form a release treatment layer was prepared. A coating liquid containing an antistatic agent (manufactured by Corcoat Co., Ltd.: product name "Corcoat WAS-15SF") was applied to the side of this PET film opposite to the side with the release treatment layer, and dried at a temperature of 23°C for 10 minutes to form a first antistatic layer, thereby obtaining a release film (1). The layer structure of the release film (1) was release treatment layer / PET film (first base film) / first antistatic layer.

[0154] (Formation of the first adhesive layer) A reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer was charged with a mixed solution of 81.8 parts ethyl acetate, 96 parts butyl acrylate, 3 parts 2-hydroxyethyl acrylate, and 1 part acrylic acid as the solvent. The internal temperature was raised to 55°C while replacing the air in the reaction vessel with nitrogen gas to eliminate oxygen. Subsequently, the entirety of a solution of 0.14 parts azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts ethyl acetate was added. The temperature was maintained at this level for 1 hour after the addition of the polymerization initiator. Then, while maintaining the internal temperature at 54-56°C, ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts / hr. When the concentration of the acrylic resin reached 35%, the addition of ethyl acetate was stopped, and the temperature was maintained at this level for another 12 hours from the start of ethyl acetate addition. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20%, and an ethyl acetate solution of the acrylic resin was prepared.

[0155] The obtained acrylic resin had a weight-average molecular weight (Mw) of 1.47 million and a polystyrene equivalent (Mw / Mn) of 5.5, as measured by GPC. The weight-average molecular weight and number-average molecular weight were measured using a GPC instrument with four "TSK gel XL" columns (manufactured by Tosoh Corporation) and one "Shodex GPC KF-802" column (manufactured by Showa Denko K.K.), a total of five columns, connected in series. Tetrahydrofuran was used as the eluent, and the measurements were performed under the conditions of a sample concentration of 5 mg / mL, sample introduction volume of 100 μL, temperature of 40°C, and flow rate of 1 mL / min. The values ​​were calculated using standard polystyrene equivalents.

[0156] To 100 parts of the solid content of the ethyl acetate solution of the acrylic resin prepared above (resin concentration: 20%), 0.3 parts of a crosslinking agent (manufactured by Tosoh Corporation: product name "Coronate L", ethyl acetate solution of an isocyanate compound, active ingredient 75%) and 0.5 parts of a silane compound (manufactured by Shin-Etsu Chemical Co., Ltd.: product name "KBM403") were mixed, and ethyl acetate was further added to obtain an adhesive composition with a solid content concentration of 14%. Note that the amount of crosslinking agent used is in parts by mass as an active ingredient.

[0157] The adhesive composition obtained above was applied to the release treatment layer side of the release film (1) using an applicator so that the thickness after drying was 25 μm, and dried at a temperature of 50°C for 60 minutes to obtain a release film (1) with an adhesive layer, in which the first adhesive layer was formed on the release treatment layer side of the release film (1).

[0158] (Fabrication of polarizing plates) As protective layers, a 20 μm thick triacetylcellulose (TAC) film and a 29 μm thick norbornene-based resin film with a hard coat layer formed on one side were prepared. As a linearly polarized layer, a PVA-based resin film with iodine, a dichroic dye, adsorbed and oriented was prepared. The thickness of the linearly polarized layer was 8 μm.

[0159] Dissolve 3 parts carboxyl group-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd.: product name "KL-318") in 100 parts by weight of water, and add a water-soluble epoxy resin, a polyamide epoxy additive (manufactured by Taoka Chemical Industry Co., Ltd.: product name "Sumire's Resin (registered trademark)") to the aqueous solution. A water-based adhesive was prepared by adding 1.5 parts of 650(30), an aqueous solution with a solid content concentration of 30%.

[0160] The TAC film prepared above was subjected to saponification treatment. The norbornene-based resin film prepared above was subjected to corona treatment on the side opposite to the hard coat layer, and on both sides of the linear polarizing layer prepared above. The saponified TAC film was bonded to one side of the linear polarizing layer via the water-based adhesive obtained above, and the corona-treated side (opposite to the hard coat layer) of the norbornene-based resin film was bonded to the other side of the linear polarizing layer via the water-based adhesive obtained above. A drying treatment was performed to form an adhesive layer, thereby obtaining a polarizing plate. The layer structure of the polarizing plate was TAC film (protective layer) / adhesive layer / linear polarizing layer / adhesive layer / norbornene-based resin film (protective layer) / hard coat layer.

[0161] (Fabrication of optical laminate (1)) A surface protection film (thickness 53 μm) was prepared by forming an acrylic adhesive layer (thickness 15 μm) on the side opposite to the second antistatic layer of a polyester resin film (second base film, thickness 38 μm) having a second antistatic layer on its surface. The layer structure of the surface protection film was second antistatic layer / second base film / acrylic adhesive layer (second adhesive layer). The acrylic adhesive layer of this surface protection film was laminated to the hard coat layer side of the norbornene resin film of the polarizing plate obtained above to obtain a polarizing plate with a surface protection film.

[0162] An optical laminate (1) was obtained by laminating the first adhesive layer side of the adhesive-coated release film (1) obtained above onto the TAC film side of the polarizing plate with surface protection film obtained above. The layer structure of the optical laminate (1) was: surface protection film (second antistatic layer / second base film / second adhesive layer) / polarizing plate (hard coat layer / protective layer / adhesive layer / linear polarizing layer / adhesive layer / protective layer) / first adhesive layer / release film (release treatment layer / first base film / first antistatic layer). The slow axis of the surface protection film and the absorption axis of the linear polarizing layer were orthogonal, and the slow axis of the release film and the absorption axis of the linear polarizing layer were orthogonal. The optical laminate (1) was evaluated for the inspectability and multi-layer production described below. The results are shown in Table 1.

[0163] [Examples 2-4] Release films (2) to (4) were obtained in the same manner as the preparation of release film (1) in Example 1, except that the amount of coating solution containing an antistatic agent was changed to form the first antistatic layer.

[0164] Optical laminates (2) to (4) were obtained in the same manner as the optical laminate (1) of Example 1, except that the release films (2) to (4) obtained above were used instead of release film (1). The following quality control evaluations and multi-layer evaluations were performed on optical laminates (2) to (4). The results are shown in Table 1.

[0165] [Comparative Example 1] A polyethylene terephthalate (PET) film (manufactured by Lintec Corporation: product name "PLR-382190") with a release agent applied to one side was prepared. A coating solution containing an antistatic agent (manufactured by Takamatsu Oil & Fat Co., Ltd.: product name "ASA-2050") was applied to the side of the PET film opposite to the side with the release agent, and the film was heated and dried at 130°C for 10 minutes to form a first antistatic layer and obtain a release film (5).

[0166] An optical laminate (5) was obtained in the same manner as the optical laminate (1) of Example 1, except that the release film (5) obtained above was used instead of the release film (1). The optical laminate (5) was evaluated for the inspectability and multi-layer properties described below. The results are shown in Table 1.

[0167] [Evaluation of quality control] A polarizing plate for inspection (linear polarizing plate; made by laminating a polyvinyl alcohol (PVA) polarizer onto a norbornene-based resin film) was set up with the PVA polarizer side facing the viewing side, and the optical laminates obtained in the examples and comparative examples were positioned so that the absorption axis direction of the linear polarizing layer was crossed with the absorption axis direction of the linear polarizing layer of the polarizing plate for inspection. The visibility of unevenness was confirmed by visual observation of light transmission. Visual observation of light transmission revealed that those with strong visible unevenness had poor inspection capabilities for defects, etc., while those with weak visible unevenness had excellent inspection capabilities. Based on this, the inspection capabilities were evaluated according to the following criteria. A: The visible inconsistencies were minimal, and the quality control was excellent. B: Although some unevenness was visible, the quality control was good. C: The visible inconsistencies were significant, resulting in poor quality control.

[0168] [Evaluation of multiple trades] For evaluation, a laminate (40 mm x 40 mm) was prepared, consisting of a surface protection film with an antistatic layer, a polarizing plate, an adhesive layer, and a release film, laminated in this order. The antistatic layer was formed on the side of the surface protection film opposite the polarizing plate. The evaluation laminate was placed on a rubber base with the release film side facing the base, and an optical laminate was laminated onto the surface protection film side of this evaluation laminate, with the surface protection film facing the release film side of the optical laminate obtained in the examples and comparative examples. With a load of 1000 g applied to the laminated optical laminate side, the evaluation laminate and the optical laminate were rubbed back and forth three times. The load was applied using a rubber part that was in contact with the optical laminate. After the rubbing operation, with the evaluation laminate and the optical laminate overlapping, the surfaces of the evaluation laminate and the optical laminate were tilted so that they were perpendicular to the horizontal plane, and it was checked whether the optical laminate had fallen off. This test was performed three times, and the multi-layer evaluation was performed according to the following criteria. a: In all three tests, the optical laminate detached. b: In three tests, the optical laminate detached twice. c: In three tests, the optical laminate detached once. d: In all three tests, the optical laminate did not detach even once.

[0169] [Table 1] [Explanation of Symbols]

[0170] 1,2 Optical laminate, 10 Polarizing plate, 11 First adhesive layer, 20,40 Release film, 21,41 First base film, 22,42 Release treatment layer, 23,43 First antistatic layer, 30,50 Surface protective film, 31,51 Second base film, 32,52 Second adhesive layer, 33,53 Second antistatic layer, 60 Polarizing plate for inspection, 61 Light source.

Claims

1. An optical laminate comprising a polarizing plate containing a linearly polarizing layer, a first adhesive layer, and a release film that can be peeled off from the first adhesive layer, laminated in this order, The release film has, in order from the first adhesive layer side, a release treatment layer, a first base film, and a first antistatic layer containing an antistatic agent. The average in-plane phase difference value of the aforementioned release film at a wavelength of 550 nm is 1000 nm or more. The average in-plane phase difference value of the first substrate film at a wavelength of 550 nm is 1000 nm or more. An optical laminate in which the difference between the maximum and minimum in-plane phase difference values ​​of the release film at a wavelength of 550 nm is 150 nm or less.

2. Furthermore, the polarizing plate has a surface protective film that can be peeled off from the polarizing plate on the side opposite to the first adhesive layer. The optical laminate according to claim 1, wherein the surface protective film comprises, in order from the polarizing plate side, a second base film and a second antistatic layer containing an antistatic agent.

3. The average in-plane phase difference value of the surface protective film at a wavelength of 550 nm is 1000 nm or more. The average in-plane phase difference value of the second substrate film at a wavelength of 550 nm is 1000 nm or more. The optical laminate according to claim 2, wherein the difference between the maximum and minimum in-plane phase difference values ​​of the surface protective film at a wavelength of 550 nm is 150 nm or less.

4. An optical laminate comprising a first adhesive layer, a polarizing plate including a linear polarizing layer, and a surface protective film that can be peeled off from the polarizing plate, laminated in this order, The surface protective film comprises, in order from the polarizing plate side, a second base film and a second antistatic layer containing an antistatic agent. The average in-plane phase difference value of the surface protective film at a wavelength of 550 nm is 1000 nm or more. The average in-plane phase difference value of the second substrate film at a wavelength of 550 nm is 1000 nm or more. An optical laminate in which the difference between the maximum and minimum in-plane phase difference values ​​at a wavelength of 550 nm of the surface protective film is 150 nm or less.

5. The optical laminate according to any one of claims 2 to 4, wherein the surface protective film further has a second adhesive layer on the polarizing plate side of the second base film.

6. Furthermore, the first adhesive layer has a release film on the side opposite to the polarizing plate side that is peelable from the first adhesive layer. The optical laminate according to claim 4, wherein the release film comprises, in order from the first adhesive layer side, a release treatment layer, a first base film, and a first antistatic layer containing an antistatic agent.

7. The surface resistance of the aforementioned release film at a temperature of 23°C and a relative humidity of 55% RH is 1.0 × 10⁻⁶. ８ Ω / □ or more 5.0×10 １４ An optical laminate according to any one of claims 1 to 3 and 6, wherein the coefficient of gravity is Ω / □ or less.

8. The surface resistance of the aforementioned surface protective film at a temperature of 23°C and a relative humidity of 55% RH is 1.0 × 10⁻⁶. ８ Ω / □ or more 1.0×10 １１ An optical laminate according to any one of claims 2 to 6, wherein the Ω / □ is less than or equal to Ω.

9. The optical laminate according to any one of claims 1 to 8, wherein the polarizing plate has a protective layer on one or both sides of the linear polarizing layer.

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