Optical laminate

Abstract

The present invention provides an optical laminate that can effectively peel off a release film even when it includes a linear polarizing layer and a retardation layer; the linear polarizing layer and the retardation layer are hardened layers containing a polymeric liquid crystal compound. The optical laminate of the present invention sequentially comprises a surface protective film, a transparent resin film, a circular polarizer, a first adhesive layer, and a release film. The surface protective film can be peeled off from the transparent resin film. The circular polarizer sequentially comprises a linear polarizing layer and a first retardation layer from the transparent resin film side. The linear polarizing layer includes a first hardened layer containing a first composition of a polymeric liquid crystal compound, and the first retardation layer includes a second hardened layer containing a second composition of a polymeric liquid crystal compound. The release film can be peeled off from the first adhesive layer.

Description

[Technical Field]

[0001] This invention relates to an optical laminate. [Previous Technology]

[0002] In display devices such as liquid crystal display devices and organic EL display devices, optical films such as linear polarizing layers, retardation layers, and laminates having such layers are used. Regarding linear polarizing layers, besides PVA polarizing films formed by adsorbing and orienting dichroic pigments such as iodine onto a polyvinyl alcohol-based resin film, liquid crystal curing layers manufactured by coating a composition containing a polymeric liquid crystal compound onto a substrate are known (e.g., Patent Document 1). Regarding retardation layers, besides retardation films that are extension films formed by extending a resin film, liquid crystal curing layers manufactured by coating a composition containing a polymeric liquid crystal compound onto a substrate are known (e.g., Patent Document 1).

[0002] [Previous Technical Documents]

[0002] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-83843

[0004] Optical film systems sometimes have an adhesive layer for application to a display device and a release film for covering and protecting the adhesive layer. In such optical film systems, the release film must be peeled off to expose the adhesive layer. For example, when applied to a display device using an automatic bonding device, the optical film, which has a release adhesive tape (hereinafter sometimes referred to as "release tape") attached to the surface of the release film, is fixed to a suction stage with suction holes, and the release film is peeled off by pulling up the release tape in this state.

[0005] However, it has been found that when the linear polarizing layer and retardation layer contained in the optical film are liquid crystal curing layers, as mentioned above, if the release tape is used to peel off the release film, sometimes not only the release film is pulled up, but the entire optical film is also pulled up, making it impossible to peel off the release film. In order to peel off the release film, a method has been devised to increase the vacuum suction force of the holding stage and improve the holding force of the optical film on the suction stage. However, at this time, sometimes traces of suction holes remain on the optical film. Traces of suction holes may hinder the inspection of optical films or have an adverse effect on the optical performance of the optical film.

[0006] The object of the present invention is to provide an optical laminate that can effectively peel off a release film even when it includes a linear polarizing layer and a phase retardation layer; the linear polarizing layer and the phase retardation layer are hardened layers containing a polymeric liquid crystal compound.

[0007] The present invention provides the following optical laminates.

[0007] [1] An optical laminate, comprising, in sequence, a surface protective film, a transparent resin film, a circular polarizing plate, a first adhesive layer, and a release film; wherein,

[0007] The aforementioned surface protective film can be peeled off from the aforementioned transparent resin film;

[0007] The aforementioned circular polarizer has a linear polarizing layer and a first phase difference layer sequentially from the aforementioned transparent resin film side. The linear polarizing layer includes a first hardened layer containing a first composition of a polymeric liquid crystal compound, and the first phase difference layer includes a second hardened layer containing a second composition of a polymeric liquid crystal compound.

[0007] The aforementioned release film system can be peeled off from the first adhesive layer.

[0007] [2] The optical laminate as described in [1], wherein the distance D from the surface of the aforementioned surface protective film on the side of the aforementioned transparent resin film to the surface of the aforementioned first adhesive layer on the side of the aforementioned circular polarizer is 20 μm or more and 60 μm or less.

[0007] The tensile modulus of the aforementioned transparent resin film at a temperature of 23°C is 1500 MPa or more and 8000 MPa or less.

[0007] 〔3〕The optical laminate as described in 〔1〕 or 〔2〕, wherein,

[0007] The aforementioned surface protective film has a second adhesive layer and a substrate film sequentially formed from the aforementioned transparent resin film side.

[0007] The tensile modulus of the aforementioned substrate film at a temperature of 23°C is above 2500 MPa and below 6000 MPa.

[0007] The thickness of the aforementioned substrate film is 30μm or more and 120μm or less.

[0007] [4] The optical laminate as described in any one of [1] to [3] has a first bonding layer between the aforementioned transparent resin film and the aforementioned circular polarizer.

[0007] [5] The optical laminate as described in any one of [1] to [4] has a diffusion suppression layer between the aforementioned transparent resin film and the aforementioned circular polarizer.

[0007] 〔6〕The optical stack as described in 〔5〕, wherein the thickness of the aforementioned diffusion suppression layer is less than 5 μm.

[0007] [7] An optical stack as described in any one of [1] to [6], wherein the aforementioned circular polarizer has a second bonding layer, which is bonded to the aforementioned linear polarizer and the aforementioned first phase difference layer.

[0007] [8] An optical laminate as described in any one of [1] to [7], wherein the polymeric liquid crystal compound contained in the aforementioned first component is a polymeric liquid crystal compound that displays a lamellae liquid crystal phase.

[0007] The aforementioned first component further includes a pigment with anisotropic absorption properties.

[0007] 〔9〕An optical laminate as described in any one of 〔1〕 to 〔8〕, wherein,

[0007] The aforementioned second hardening layer is used to harden the aforementioned polymeric liquid crystal compound in a state where the surface of the aforementioned first phase difference layer is horizontally oriented.

[0007] 〔10〕An optical laminate as described in any one of 〔1〕 to 〔9〕, wherein,

[0007] The aforementioned circular polarizer has a second phase retardation layer on the side opposite to the aforementioned linear polarizer layer, and the second phase retardation layer includes a third hardened layer containing a third composition of a polymeric liquid crystal compound.

[0007]

[11] The optical stack as described in

[10] , wherein the aforementioned third hardening layer is hardened in a state in which the aforementioned polymeric liquid crystal compound is oriented perpendicularly to the surface of the aforementioned second retardation layer.

[0007] 〔12〕An optical laminate as described in any one of 〔1〕 to 〔11〕, wherein the adhesion force F1 between the aforementioned surface protective film and the aforementioned transparent resin film, and the adhesion force F2 between the aforementioned first adhesive layer and the aforementioned release film, satisfy the following relationship (1).

[0007] |F1-F2|≧0.02[N / 25mm] (1)

[0008] The optical laminate according to the present invention can effectively peel off the release film. [Simplified Explanation of the Diagram]

[0009] Figure 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0009] Figure 2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention.

[0009] Figure 3 is a top view illustrating an example of a method for peeling a release film from an optical laminate of an embodiment of the present invention.

[0009] Figure 4 is a cross-sectional view illustrating an example of a method for peeling a release film from an optical laminate of an embodiment of the present invention.

Implementation Method

[0010] Hereinafter, a preferred embodiment of the optical laminate will be described with reference to the drawings.

[0010] (Optical laminate)

[0010] Figures 1 and 2 are schematic cross-sectional views of an optical laminate according to one embodiment of the present invention. Figures 3 and 4 are top views and cross-sectional views, respectively, illustrating an example of a method for peeling a release film from an optical laminate according to an embodiment of the present invention.

[0011] The optical laminates 1 and 2 shown in Figures 1 and 2 sequentially have a surface protective film 10, a transparent resin film 15, circular polarizing plates 30 and 40, a first adhesive layer 21, and a release film 23. As shown in Figure 2, the optical laminate 2 may have a first diffusion suppression layer 35 (diffusion suppression layer) between the transparent resin film 15 and the circular polarizing plate 40.

[0012] The surface protective film 10 can be peeled off from the transparent resin film 15 and is in contact with the transparent resin film 15. The surface protective film 10 can be peeled off from the transparent resin film 15 while maintaining the shape of both the surface protective film 10 and the transparent resin film 15. The surface protective film 10 can be a self-adhesive film. In this case, the surface protective film 10 is a self-adhesive separate film, and it is directly in contact with the transparent resin film 15. As shown in Figures 1 and 2, the surface protective film 10 may have a second adhesive layer 12 and a first substrate film 11 (substrate film) sequentially from the transparent resin film 15 side. In this case, the second adhesive layer 12 constituting the surface protective film 10 is in contact with the transparent resin film 15.

[0013] The transparent resin film 15 can be directly bonded to the circular polarizers 30 and 40, but as shown in Figures 1 and 2, they can be laminated with a first bonding layer 25 (adhesive layer or adhesive layer) in between. For example, as shown in Figure 1, when the optical laminate 1 does not have a first diffusion suppression layer 35 between the transparent resin film 15 and the circular polarizer 30, the transparent resin film 15 and the circular polarizer 30 can be directly bonded, or they can be directly bonded to the first bonding layer 25 respectively. For example, as shown in Figure 2, when the optical laminate 2 has a first diffusion suppression layer 35 between the transparent resin film 15 and the circular polarizer 40, the transparent resin film 15 and the first diffusion suppression layer 35 can be directly bonded, or they can be directly bonded to the first bonding layer 25 respectively. The first diffusion suppression layer 35 and the circular polarizer 40 are preferably directly bonded, but they can also be laminated with a bonding layer (adhesive layer or adhesive layer) in between.

[0014] The circular polarizers 30 and 40 sequentially have a linear polarizing layer 31 and a first phase retardation layer 33 starting from the transparent resin film 15 side. The outermost surface of the circular polarizers 30 and 40 on the side closest to the transparent resin film 15 may be the linear polarizing layer 31. The linear polarizing layer 31 and the first phase retardation layer 33 may be directly connected. Alternatively, as shown in Figures 1 and 2, the circular polarizers 30 and 40 may further have a second bonding layer 32 (adhesive layer or adhesive layer) for bonding the linear polarizing layer 31 and the first phase retardation layer 33, and the linear polarizing layer 31 and the first phase retardation layer 33 may be directly connected to the second bonding layer 32 respectively.

[0015] As shown in Figure 2, the circular polarizer 40 may have a second diffusion suppression layer 36 between the linear polarizing layer 31 and the first phase retardation layer 33. Preferably, the second diffusion suppression layer 36 and the linear polarizing layer 31 can be directly connected, but they can also be laminated with an adhesive layer (adhesive layer or bonding agent layer) in between. The second diffusion suppression layer 36 and the first phase retardation layer 33 can be directly connected, or they can be laminated with an adhesive layer (adhesive layer or bonding agent layer) in between.

[0016] As shown in Figure 2, the circular polarizer 40 may have a second phase retardation layer 38 on the side opposite to the linear polarizer 31, after the first phase retardation layer 33. When the circular polarizer 40 has the second phase retardation layer 38, the first phase retardation layer 33 and the second phase retardation layer 38 can be directly connected. However, as shown in Figure 2, a third bonding layer 37 (adhesive layer or adhesive layer) may be provided to bond the first phase retardation layer 33 and the second phase retardation layer 38. In this case, the first phase retardation layer 33 and the second phase retardation layer 38 are preferably directly connected to the third bonding layer 37, respectively.

[0017] In addition to the first phase retardation layer 33 and the second phase retardation layer 38, the circular polarizer 40 may have one or more third phase retardation layers. The deposition position of the third phase retardation layer is not particularly limited; for example, it may be deposited on the side opposite to the first phase retardation layer 33 of the second phase retardation layer 38, or it may be deposited between the first phase retardation layer 33 and the second phase retardation layer 38. The third phase retardation layer may be directly bonded to other layers, or it may be deposited with an adhesive layer (adhesive layer or bonding agent layer) in between.

[0018] The linear polarizing layer 31 comprises a first hardened layer containing a first composition of a polymerizable liquid crystal compound. The first retardation layer 33 comprises a second hardened layer containing a second composition of a polymerizable liquid crystal compound. The second retardation layer 38 preferably comprises a second hardened layer containing a second composition of a polymerizable liquid crystal compound. The third retardation layer preferably comprises a third hardened layer containing a third composition of a polymerizable liquid crystal compound.

[0019] The circular polarizing plates 30 and 40 are preferably in direct contact with the first adhesive layer 21. The release film 23 can be peeled off from the first adhesive layer 21 and is in contact with the first adhesive layer 21. The release film 23 can be peeled off from the first adhesive layer 21 while maintaining the shape of the release film 23 and the first adhesive layer 21. When the release film 23 is peeled off, the first adhesive layer 21 that was originally in contact with it will be exposed.

[0020] Optical laminates 1 and 2 are applied to display elements of display devices such as organic EL display devices by means of the first adhesive layer 21 exposed by peeling off the release film 23. When peeling off the release film 23 from optical laminates 1 and 2, firstly, as shown in Figures 3 and 4, optical laminates 1 and 2 with a release adhesive tape (hereinafter sometimes referred to as "release tape") 45 attached to the surface of the release film 23 are fixed by vacuum suction or the like, with the side of the surface protective film 10 becoming the suction stage 46 with suction holes. After this, by pulling the release tape 45 in the direction of the arrows shown in Figures 3 and 4 (a) to (c), optical laminates 1 and 2 are separated between the release film 23 and the first adhesive layer 21, thereby peeling off the release film 23.

[0021] In the optical stacks 1 and 2, the linear polarizing layer 31 and the first retardation layer 33 contained in the circular polarizers 30 and 40 are composed of a hardened layer containing a polymeric liquid crystal compound, and their thickness is small. For example, compared with a PVA polarizing film containing a polyvinyl alcohol-based resin film and adsorbing dichroic pigments such as iodine, and a retardation film that is an extended film after extending the resin film, the rigidity of the circular polarizers 30 and 40 is smaller.

[0022] Optical laminates 1 and 2 have a transparent resin film 15 between the surface protective film 10 and the circular polarizing plates 30 and 40. Therefore, as described above, even if the rigidity of the circular polarizing plates 30 and 40 is low, the rigidity of the optical laminates 1 and 2 can be increased by the transparent resin film 15. Thus, by pulling up the peeling tape 45 as shown in Figures 4(a) to (c), the release film 23 can be suitably peeled off from the optical laminates 1 and 2.

[0023] In contrast, the linear polarizing layer and the first phase difference layer are the aforementioned hardened layers, and the optical laminate without a transparent resin film lacks sufficient rigidity. Therefore, when the release tape is pulled up, not only does the release film rise, but the optical laminate also rises from the suction stage, making it difficult to peel off the release film. In order to suppress the rise of the optical laminate from the suction stage, if the suction holding force of the optical laminate on the suction stage is increased, there is a risk of residual suction hole marks on the surface protective film and / or the circular polarizing plate. The suction hole marks generated on the optical laminate may hinder the inspection process and reduce the display performance when the optical laminate is applied to a display device. On the other hand, according to the optical laminates 1 and 2 of this embodiment, the release film 23 can be peeled off well, or the residual suction hole marks on the optical laminates 1 and 2 can be suppressed.

[0024] In the optical laminates 1 and 2, the distance D from the surface of the surface protective film 10 on the side adjacent to the transparent resin film 15 to the surface of the first adhesive layer 21 on the side adjacent to the circular polarizer 30 and 40 is preferably 20 μm or more, and can be more than 20 μm, or 25 μm or more, or 30 μm or more, and preferably 60 μm or less, or 55 μm or less, or 50 μm or less, or 40 μm or less. When the distance D is within the above range, as will be described later, by setting the tensile modulus of elasticity of the transparent resin film 15 at a temperature of 23°C to be in the range of 1500 MPa or more and 8000 MPa or less, the release film 23 can be peeled off from the optical laminates 1 and 2 more effectively.

[0025] In optical laminates 1 and 2, it is preferable that the adhesion force F1 between the surface protective film 10 and the transparent resin film 15 and the adhesion force F2 between the first adhesive layer 21 and the release film 23 satisfy the relationship of formula (1).

[0025] |F1-F2|≧0.02[N / 25mm] (1)

[0026] The adhesion force F1 is the peeling force when peeling the surface protective film 10 from the optical laminates 1 and 2, which is equivalent to the force required to separate the surface protective film 10 from the transparent resin film 15 in the optical laminates 1 and 2. The adhesion force F2 is the peeling force when peeling the release film 23 from the optical laminates 1 and 2, and is equivalent to the force required to separate the release film 23 from the first adhesive layer 21 in the optical laminates 1 and 2.

[0027] |F1-F2| can be 0.03N / 25mm or more, or 0.04N / 25mm or more, or 0.20N / 25mm or less, or 0.10N / 25mm or less, or 0.08N / 25mm or less.

[0028] By satisfying the relationship between the adhesion force F1 and the adhesion force F2 in the above equation (1), an appropriate strength relationship can be generated in the peeling force when peeling the surface protective film 10 and the release film 23 from the optical laminates 1 and 2. In this way, the surface protective film 10 and the release film 23 can be peeled off in the desired order. For example, when peeling the release film 23 from the optical laminates 1 and 2 first, it is sufficient to make the adhesion force F2 less than the adhesion force F1, and when peeling the surface protective film 10 from the optical laminates 1 and 2 first, it is sufficient to make the adhesion force F1 less than the adhesion force F2.

[0029] The adhesion strength F1 can be, for example, 0.04 N / 25 mm or more, 0.06 N / 25 mm or more, 0.08 N / 25 mm or more, or less than 0.30 N / 25 mm, less than 0.25 N / 25 mm, less than 0.20 N / 25 mm, or less than 0.15 N / 25 mm. With the adhesion strength F1 within the above range, the surface protective film 10 can be easily peeled off from the optical laminates 1 and 2.

[0030] The adhesion strength F2 can be, for example, 0.01 N / 25 mm or more, 0.02 N / 25 mm or more, 0.03 N / 25 mm or more, or 0.05 N / 25 mm or more, or less than 0.30 N / 25 mm, less than 0.25 N / 25 mm, less than 0.20 N / 25 mm, or less than 0.15 N / 25 mm. With the adhesion strength F2 within the above range, the release film 23 can be easily peeled off from the optical laminates 1 and 2.

[0031] Adhesion F1 and adhesion F2 can be adjusted by adjusting the type and thickness of the surface protective film 10 and the release film 23, or by applying a modification treatment to the surface of the surface protective film 10 that is in contact with the transparent resin film 15 and the surface of the release film 23 that is in contact with the first adhesive layer 21.

[0032] The adhesion F1 and adhesion F2 can be determined by the method described in the examples below, and can be determined according to the 90° peel test method specified in JIS K 6854-1:1999.

[0033] The following describes in detail the components that constitute the optical laminate and the components used to manufacture the optical laminate.

[0034] (Surface protective film)

[0034] The surface protective film 10 is present on the outermost layer of the optical laminates 1 and 2, and is configured to be peelable from the transparent resin film 15. The surface protective film 10 can be used to cover and protect the surface of the transparent resin film.

[0035] The thickness of the surface protective film 10 may be 30 μm or more, or 40 μm or more, or 50 μm or more, or less than 150 μm, or less than 120 μm, or less than 100 μm, or less than 90 μm.

[0036] As described above, the surface protective film 10 may have a multilayer structure of a first substrate film 11 and a second adhesive layer 12, or it may be a self-adhesive film with a single-layer structure composed of the first substrate film 11. The surface protective film 10 may further have antistatic properties and / or antifouling properties, etc.

[0037] The tensile modulus of elasticity of the first substrate film 11 at a temperature of 23°C may be 2500 MPa or more, or 3000 MPa or more, or 3500 MPa or more, or 6000 MPa or less, or 5500 MPa or less.

[0038] The thickness of the first substrate film 11 may be 30 μm or more, or 35 μm or more, or 40 μm or more, or 50 μm or more, or 120 μm or less, or 100 μm or less, or 80 μm or less.

[0039] Since the tensile modulus of the first substrate film 11 is within the above-mentioned range and the thickness is within the above-mentioned range, the release film 23 can be easily and well peeled off from the optical laminates 1 and 2, and the optical laminates 1 and 2 after the release film 23 has been peeled off can be easily and well bonded to the display device. The tensile modulus of the first substrate film 11 can be measured according to the method described in the embodiments below.

[0040] The first substrate film 11 can be, for example, a film made of a resin known in the field of optical films. Examples of resins constituting the first substrate film include: polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norethene polymers; polyvinyl alcohol; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; poly(meth)acrylate; cellulose resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polycarbonate; polyurethane; polyether ether; polyetherketone; polyphenylene sulfide; polyphenylene ether, etc. From the viewpoint of smoothness or quality as a coating substrate, it is preferable to select at least one of cyclic olefin resins, cellulose resins, and polyesters. These resins can be used alone or in combination of two or more. The above-mentioned resins can be used to form a film by known methods such as solvent casting or melt extrusion. "(Meth)acrylic acid" means selected from at least one of acrylic acid and methacrylic acid.

[0041] When the surface protective film 10 has self-adhesive properties, it can be formed using polypropylene resin and polyethylene resin, etc.

[0042] When the surface protective film 10 has antistatic and / or antifouling properties, the first substrate film 11 may also have antistatic and / or antifouling properties, or a surface functional layer with antistatic and / or antifouling properties may be applied to the surface of the first substrate film 11. It is preferable that the surface functional layer is directly in contact with the first substrate film 11. When the surface protective film 10 has a second adhesive layer 12, the surface functional layer is preferably disposed on the side of the first substrate film 11 opposite to the side of the second adhesive layer 12.

[0043] In order to impart the desired release properties and / or adhesion, the first substrate film 11 may be subjected to surface modification treatments such as corona treatment, plasma treatment, and flame treatment, depending on the type of layer adjacent to the first substrate film 11.

[0044] (Transparent resin film)

[0044] The transparent resin film 15 is provided to impart appropriate rigidity to the optical laminates 1 and 2. The tensile modulus of elasticity of the transparent resin film at a temperature of 23°C is preferably 1500 MPa or higher, but can be 1800 MPa or higher, 2000 MPa or higher, 3000 MPa or higher, or 8000 MPa or lower, 7000 MPa or lower, 6000 MPa or lower, or 5000 MPa or lower. The tensile modulus of elasticity of the transparent resin film 15 can be measured by the method described in the embodiments below.

[0045] By ensuring that the tensile modulus of the transparent resin film 15 is within the aforementioned range, even when the distance D between the optical laminates 1 and 2 is between 20 μm and 60 μm, appropriate rigidity can be imparted to the optical laminates 1 and 2. Therefore, as described above, by using the release tape 45 (Figs. 3 and 4), traces of suction holes can be prevented from remaining on the optical laminates 1 and 2, and the release film 23 can be appropriately peeled off.

[0046] The thickness of the transparent resin film 15 may be, for example, 5 μm or more, or 10 μm or more, or 12 μm or more, or 15 μm or more, or 40 μm or less, or 30 μm or less, or 25 μm or less.

[0047] The transparent resin film 15 can be, for example, a film made of a resin known in the field of optical films. Examples of resins constituting the transparent resin film 15 include the resins constituting the first substrate film 11 described above. Preferably, it is selected from at least one of cyclic olefin resins, cellulose resins, and polyesters. The aforementioned resin can be used to form a film by known methods such as solvent casting or melt extrusion.

[0048] In order to impart the desired adhesion, the transparent resin film 15 may be subjected to surface modification treatments such as corona treatment, plasma treatment, and flame treatment, depending on the type of layer adjacent to the transparent resin film 15.

[0049] (Circular polarizing plate)

[0049] The circular polarizers 30 and 40 can convert light incident from the linear polarizing layer 31 into linearly polarized light, and then convert the linearly polarized light into circularly polarized light. When the converted circularly polarized light is reflected and then incident on the circular polarizers 30 and 40 from the first phase difference layer 33, the circular polarizers 30 and 40 can convert the circularly polarized light into linearly polarized light, and the linearly polarized light is absorbed by the linear polarizing layer.

[0050] The linear polarizing layer 31 and the first retardation layer 33 are laminated directly or in between the second diffusion suppression layer 36 and / or the second bonding layer 32. The adhesion between the linear polarizing layer 31 and the first retardation layer 33 is typically 2 N / 25 mm or more. The linear polarizing layer 31 and the first retardation layer 33 are laminated with an adhesion that does not cause peeling between them, i.e., the magnitude of material damage. The adhesion between the linear polarizing layer 31 and the first retardation layer 33 is measured according to the 90° peel test method specified in JIS K 6854-1:1999, as described in the embodiments below.

[0051] (Linear polarizing layer)

[0051] The linear polarizing layer 31 has the following properties: when unpolarized light is incident, it allows linearly polarized light with a vibration plane orthogonal to the absorption axis to pass through. The linear polarizing layer 31 may include a first hardening layer containing a first composition of a polymeric liquid crystal compound, and a first alignment layer for orienting the polymeric liquid crystal compound.

[0052] The polymeric liquid crystal compound contained in the first composition is a compound that contains at least one polymeric group and exhibits liquid crystal properties. The polymeric liquid crystal compound may be a compound exhibiting anisotropic absorption. When the polymeric liquid crystal compound exhibits anisotropic absorption, the first composition may not contain a pigment exhibiting anisotropic absorption.

[0053] The term "polymerizable group" refers to a group that can participate in polymerization reactions by generating active free radicals or acids from polymerization initiators, with photopolymerizable groups being preferred. Examples of polymerizable groups include vinyl, ethoxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, (meth)acrylyl, ethylene oxide, and oxetyl. Among these, free radical polymerizable groups are preferred, (meth)acrylyl, vinyl, and ethoxy are more preferred, and (meth)acrylyl is even more preferred.

[0054] The polymeric liquid crystal compound contained in the first component is preferably a compound exhibiting lamellar liquid crystal properties. By using a polymeric liquid crystal compound exhibiting lamellar liquid crystal properties, a linear polarizing layer with high orientation order can be formed. From the viewpoint of achieving higher orientation order, the liquid crystal state exhibited by the polymeric liquid crystal compound is preferably a higher-order lamellar phase (higher-order lamellar liquid crystal state). Here, the term "higher-order lamellar phase" refers to lamellar phase B, lamellar phase D, lamellar phase E, lamellar phase F, lamellar phase G, lamellar phase H, lamellar phase I, lamellar phase J, lamellar phase K, and lamellar phase L, among which lamellar phase B, lamellar phase F, and lamellar phase I are preferred. The liquid crystal property can be thermotropic liquid crystal or liquidotropic liquid crystal, but from the perspective of controllable dense film thickness, thermotropic liquid crystal is preferred. Furthermore, polymeric liquid crystal compounds can be monomers, but they can also be oligomers or polymers formed by polymerizing polymeric groups.

[0055] In addition to the polymerizable liquid crystal compound, the first component system may also contain a pigment exhibiting anisotropic absorption. Anisotropic absorption refers to a pigment whose absorbance along its long axis and along its short axis are different. The pigment exhibiting anisotropic absorption is not particularly limited as long as it possesses the aforementioned properties; it can be a dye or a pigment. Furthermore, it can be used by combining two or more dyes or pigments separately, or by combining dyes and pigments.

[0056] A pigment with anisotropic absorption is preferably one that has a maximum absorption wavelength (λMAX) in the wavelength range of 300 nm to 700 nm. Examples of pigments with such anisotropic absorption include acridine pigments, aziridine pigments, anthocyanins, naphthalene pigments, azo pigments, and anthraquinone pigments. Among these, azo pigments are preferred. Examples of azo pigments include monoazo pigments, diazo pigments, triazo pigments, tetraazo pigments, and diphenylethylene azo pigments, with diazo pigments and triazo pigments being preferred. Examples of pigments with anisotropic absorption include those exemplified in Japanese Patent Application Publication No. 2013-101328.

[0057] In addition to the polymerizable liquid crystal compound and the pigment with anisotropic absorption described above, the first component system may also include a solvent, a polymerization initiator such as a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, an antioxidant, a release agent, a stabilizer, a colorant, a flame retardant, and a lubricant. Known methods may be used for such systems, for example, those exemplified in Japanese Patent Application Publication Nos. 2017-102479 and 2017-83843.

[0058] The linear polarizing layer 31 may include a first orientation layer. The first orientation layer may be disposed on the side of the first phase difference layer 33 of the first hardening layer, or on the side of the transparent resin film 15 of the first hardening layer.

[0059] The first alignment layer system has an alignment limiting force that orients the polymerizable liquid crystal compound in a desired direction. Preferably, the first alignment layer has solvent resistance that prevents dissolution by coating of the first composition, and heat resistance for heat treatment used to remove solvents or orient the polymerizable liquid crystal compound. Examples of the first alignment layer system include an alignment polymer layer formed of an alignment polymer, a photoalignment polymer layer formed of a photoalignment polymer, and a groove alignment layer having a textured surface or a plurality of grooves. From the viewpoint of accuracy and quality of the alignment angle, a photoalignment polymer layer is preferred as the first alignment layer system. Examples of the first alignment layer exemplified in Japanese Patent Application Publication No. 2013-33249 are also possible.

[0060] The linear polarizing layer 31 can be manufactured using the polarizing layer manufacturing method described in Japanese Patent Application Publication No. 2013-33249, etc. The first curing layer can be formed, for example, by forming a coating film by coating a first composition onto a first orientation layer and then curing (hardening) the coating film. Alternatively, the first curing layer can be formed by coating a first composition onto a substrate layer to form a coating film and then extending the coating film together with the substrate layer.

[0061] (1st phase difference layer, 2nd phase difference layer, 3rd phase difference layer)

[0061] The first retardation layer 33 is a second hardened layer containing a second composition of a polymerizable liquid crystal compound, and may also include a second alignment layer for orienting the polymerizable liquid crystal compound. The second retardation layer 38 is a third hardened layer containing a third composition of a polymerizable liquid crystal compound, and may also include a third alignment layer for orienting the polymerizable liquid crystal compound. The third retardation layer is a fourth hardened layer containing a fourth composition of a polymerizable liquid crystal compound, and may also include a fourth alignment layer for orienting the polymerizable liquid crystal compound. The second to fourth alignment layers may be disposed on the linear polarizing layer 31 side of the second to fourth hardened layers, or on the first adhesive layer 21 side of the second to fourth hardened layers.

[0062] As shown in Figure 1, when the circular polarizer 30 has a linear polarizing layer 31 and a first phase difference layer 33, the second hardening layer contained in the first phase difference layer 33 is preferably hardened in a state in which the polymeric liquid crystal compound is oriented in a horizontal direction relative to the surface of the first phase difference layer 33.

[0063] The first phase difference layer 33 is preferably a λ / 4 phase difference layer that satisfies the relationship shown in the following equation (2).

[0063] 120nm≦Re(550)≦170nm (2)

[0063] [In equation (2), Re(550) represents the in-plane phase difference value of the first phase difference layer at a wavelength of 550 nm.]

[0064] In equation (2), the in-plane phase difference Re(550) can be above 125nm, or above 130nm, or below 165nm, or below 160nm.

[0065] The first phase difference layer 33 is preferably a λ / 4 phase difference layer that satisfies the above equation (2) and satisfies the inverse wavelength dispersion of the following equations (3) and (4).

[0065] Re(450) / Re(550)≦1.00 (3)

[0065] Re(650) / Re(550)≧1.00 (4)

[0065] [In equations (3) and (4),

[0065] Re(450) represents the in-plane phase difference value of the first phase difference layer at a wavelength of 450nm.

[0065] Re(550) represents the in-plane phase difference value of the first phase difference layer at a wavelength of 550nm.

[0065] Re(650) represents the in-plane phase difference value of the first phase difference layer at a wavelength of 650 nm.

[0066] In formula (3), Re(450) / Re(550) can be 0.70 or more, or 0.78 or more, or 0.92 or less, or 0.90 or less, or 0.87 or less, or 0.86 or less, or 0.85 or less. In formula (4), Re(650) / Re(550) can be 1.01 or more, or 1.02 or more.

[0067] As shown in Figure 2, when the circular polarizer 40 has a linear polarizing layer 31, a first phase difference layer 33, and a second phase difference layer 38, the combination of the first phase difference layer 33 and the second phase difference layer 38 can be listed as [i] the combination of the λ / 4 phase difference layer and the positive C layer, and [ii] the combination of the λ / 2 phase difference layer and the λ / 4 phase difference layer.

[0068] When the first phase retardation layer 33 is a λ / 4 phase retardation layer, as described above, it is preferable to harden the polymeric liquid crystal compound in a horizontal orientation relative to the surface of the first phase retardation layer 33. When the second phase retardation layer 38 is a λ / 4 phase retardation layer, the third hardened layer contained in the second phase retardation layer 38 is preferably hardened in a horizontal orientation relative to the surface of the second phase retardation layer 38. Furthermore, when the first phase retardation layer 33 or the second phase retardation layer 38 is a λ / 4 phase retardation layer, it is preferable to satisfy the relationship in equation (2) above. In addition to equation (2) above, the relationships in equations (3) and (4) above can also be satisfied.

[0069] In the case of [i] above, and when the first phase retardation layer 33 is a positive C layer, the second hardening layer contained in the first phase retardation layer 33 is preferably hardened in a state in which the polymeric liquid crystal compound is oriented perpendicularly to the surface of the first phase retardation layer 33. In the case of [i] above, and when the second phase retardation layer 38 is a positive C layer, the third hardening layer contained in the second phase retardation layer 38 is preferably hardened in a state in which the polymeric liquid crystal compound is oriented perpendicularly to the surface of the second phase retardation layer 38.

[0070] The positive C layer system is preferably satisfied with the following relationship (5).

[0070] -100nm≦Rth(550)≦-40nm (5)

[0070] [In Equation (5), Rth(550) represents the phase difference value of the first or second phase difference layer in the thickness direction at a wavelength of 550 nm.]

[0071] In equation (5), the phase difference value Rth(550) in the thickness direction can be above -90nm, above -80nm, or below -50nm.

[0072] In the case of [ii] above, when the first phase retardation layer 33 is a λ / 2 phase retardation layer, the second hardening layer contained in the first phase retardation layer 33 is preferably hardened such that the polymeric liquid crystal compound is horizontally oriented relative to the surface of the first phase retardation layer 33. In the case of [ii] above, when the second phase retardation layer 38 is a λ / 2 phase retardation layer, the third hardening layer contained in the second phase retardation layer 38 is preferably hardened such that the polymeric liquid crystal compound is horizontally oriented relative to the surface of the second phase retardation layer 38.

[0073] The λ / 2 phase difference layer system is better if it satisfies the relationship of the following equation (6).

[0073] 200nm≦Re(550)≦300nm (6)

[0073] [In Equation (6), Re(550) represents the in-plane phase difference value of the first or second phase difference layer at a wavelength of 550 nm.]

[0074] In equation (6), the in-plane phase difference Re(550) can be above 220nm or below 280nm.

[0075] The in-plane phase difference values ​​Re(550) and Re(450), and the phase difference value Rth(550) in the thickness direction can be determined, for example, by measurement performed by a phase difference measuring device.

[0076] The polymeric liquid crystal compound used to form the second, third, and fourth hardened layers can be a known polymeric liquid crystal compound. The polymeric liquid crystal compound is a compound having at least one polymeric group and exhibiting liquid crystal properties.

[0077] There is no particular limitation on the type of polymerizable liquid crystal compound; rod-shaped liquid crystal compounds, disk-shaped liquid crystal compounds, and mixtures thereof may be used. A phase difference is displayed by hardening a hardened layer system formed by polymerizing the polymerizable liquid crystal compound, thereby oriented the polymerizable liquid crystal compound in a suitable direction. When the rod-shaped polymerizable liquid crystal compound is oriented horizontally or vertically relative to the plane of the display device, the optical axis of the polymerizable liquid crystal compound is aligned with the long axis direction of the polymerizable liquid crystal compound. When the disk-shaped polymerizable liquid crystal compound is oriented, its optical axis exists in a direction perpendicular to the disk surface of the polymerizable liquid crystal compound. For example, the type of rod-shaped polymerizable liquid crystal compound described in Japanese Patent Application Publication No. 11-513019 (claim 1, etc.) may be suitable. As a disc-shaped polymeric liquid crystal compound system, it is suitable to use the methods described in Japanese Patent Application Publication No. 2007-108732 (paragraphs

[0020] to

[0067] , etc.) and Japanese Patent Application Publication No. 2010-244038 (paragraphs

[0013] to

[0108] , etc.).

[0078] The polymerizable group system of the so-called polymerizable liquid crystal compound, as described above, refers to the group that participates in the polymerization reaction, with photopolymerizable groups being preferred. The so-called photopolymerizable group refers to a group that can participate in the polymerization reaction through active free radicals or acids generated from photopolymerization initiators. Examples of polymerizable groups include vinyl, ethoxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, (meth)acryloxy, ethylene oxide, oxetyl, styryl, and allyl. Among these, (meth)acryloxy, ethoxy, ethylene oxide, and oxetyl are preferred, with acryloxy being even more preferred. The liquid crystal system of the polymerizable liquid crystal compound can be thermotropic or liquidotropic. If classified by degree of order, thermotropic liquid crystals can be nematic liquid crystals or lamellar liquid crystals. In order to form a hardened layer of a polymeric liquid crystal compound, when two or more types of polymeric liquid crystal compounds are used, it is preferable that at least one type has two or more polymeric groups in its molecule. "(meth)acrylyl" means at least one selected from acrylyl and methacrylyl.

[0079] The liquid crystal system displayed by the polymeric liquid crystal compound can be a thermotropic liquid crystal or a liquidotropic liquid crystal, but in terms of the point where a dense film thickness can be controlled, a thermotropic liquid crystal is preferred. Furthermore, the phase order structure system in the thermotropic liquid crystal can be a nematic liquid crystal, a lamellar liquid crystal, or a butterfly liquid crystal. Two or more polymeric liquid crystal compounds can be used alone or in combination.

[0080] Polymerizable liquid crystal compounds with so-called T-shaped or H-shaped molecular structures tend to exhibit reverse wavelength dispersion when polymerized and hardened, while polymerizable liquid crystal compounds with T-shaped molecular structures tend to exhibit even stronger reverse wavelength dispersion.

[0081] The first phase retardation layer 33, the second phase retardation layer 38, and the third phase retardation layer may respectively include a second alignment layer, a third alignment layer, and a fourth alignment layer. The second to fourth alignment layers have an alignment limiting force that orients the polymeric liquid crystal compound in a desired direction. The second to fourth alignment layers may each be independently a vertical alignment layer formed by aligning the molecular axis of the polymeric liquid crystal compound perpendicularly to the plane of the display device, a horizontal alignment layer formed by aligning the molecular axis of the polymeric liquid crystal compound horizontally to the plane of the display device, or an oblique alignment layer formed by aligning the molecular axis of the polymeric liquid crystal compound obliquely to the plane of the display device. From the viewpoint of the accuracy and quality of the alignment angle, a photo-aligned polymer layer is preferred.

[0082] Preferably, the second to fourth alignment layers have solvent resistance that prevents dissolution by coatings containing the second to fourth components of the polymeric liquid crystal compound, and heat resistance for heat treatments used to remove solvents or orient the polymeric liquid crystal compound. Examples of the second to fourth alignment layers include an alignment polymer layer formed of an alignment polymer, a photoalignment polymer layer formed of a photoalignment polymer, and a groove alignment layer having a textured surface or a plurality of grooves on its surface.

[0083] The second to fourth components each comprise a polymerizable liquid crystal compound, a solvent, and various additives as needed. The second to fourth hardened layers can be formed by coating the second to fourth components onto the second to fourth alignment layers to form a coating film, and then curing (hardening) the coating film. Alternatively, the second to fourth components can be coated onto a substrate layer to form a coating film, and then the coating film can be extended together with the substrate layer to form the second to fourth hardened layers. Examples of additives included in the second to fourth components include polymerization initiators, reactive additives, leveling agents, polymerization inhibitors, etc. Solvents, polymerization initiators, reactive additives, leveling agents, polymerization inhibitors, etc., can be those known to be suitable.

[0084] A film formed by casting resin can be used as the substrate layer system, such as a film formed using the resin constituting the first substrate film described above. The thickness of the substrate layer is not particularly limited, but from the perspective of workability such as strength or operability, it is generally preferred to be 1 to 300 μm or less, more preferably 20 to 200 μm, and even more preferably 30 to 120 μm. The substrate layer system can be assembled in the display device together with the first to third retardation layers, or the substrate layer can be peeled off and only the second to fourth hardening layers, or the second hardening layer and the second alignment layer, the third hardening layer and the third alignment layer, or the fourth hardening layer and the fourth alignment layer can be assembled in the display device. When the substrate layer is assembled in the display device, the thickness of the substrate layer may be less than 30 μm, for example, it may be 25 μm or less.

[0085] The thickness of the first phase difference layer to the third phase difference layer can be 0.1 μm or more, or 0.2 μm or more, or 3 μm or less, or 2 μm or less, respectively.

[0086] (First adhesive layer, second adhesive layer)

[0086] The first adhesive layer 21 and the second adhesive layer 12 are adhesive layers formed using an adhesive composition. An adhesive composition or a reaction product of an adhesive composition exhibits adhesion by attaching itself to a substrate such as a display element of a display device; this is also known as a pressure-sensitive adhesive. Furthermore, the adhesive layer formed using the active energy line curing type adhesive composition described later can have its cross-linking degree or adhesion strength adjusted by irradiating an active energy line.

[0087] Adhesives with excellent optical transparency can be used without particular limitation as the adhesive composition system. For example, adhesive compositions containing matrix polymers such as acrylic polymers, urethane polymers, polysiloxane polymers, and polyvinyl ethers can be used. Furthermore, the adhesive composition system can be an active energy line curing type adhesive composition or a thermosetting type adhesive composition. Among these, an acrylic resin as the matrix polymer adhesive composition with excellent transparency, adhesion, re-peelability (reworkability), weather resistance, and heat resistance is suitable. The adhesive layer is preferably composed of a reaction product of an adhesive composition containing (meth)acrylic resin, a crosslinking agent, and a silane compound, and may also contain other components.

[0088] The active energy line curing adhesive composition is formed by incorporating a polyfunctional acrylate or other UV-curable compound into the adhesive composition described above. The resulting layer is then irradiated with ultraviolet light to cure it, thereby forming a harder adhesive layer. The active energy line curing adhesive has the property of curing upon irradiation with energy lines such as ultraviolet light or electron beams. The active energy line curing adhesive also possesses adhesiveness before energy line irradiation, thus exhibiting the property of adhering closely to the substrate and adjusting the adhesion through curing by energy line irradiation.

[0089] The adhesive composition and the active energy line hardening type adhesive composition may contain additives such as antioxidants, tackifiers, thermoplastic resins, fillers, flow modifiers, plasticizers, defoamers, antistatic agents, and solvents as needed.

[0090] The thickness of the first adhesive layer 21 and the second adhesive layer 12 is not particularly limited, but may be 5 μm or more, or 10 μm or more, or 15 μm or more, or 20 μm or more, or 25 μm or more, or less than 300 μm, or less than 250 μm, or less than 100 μm, or less than 50 μm.

[0091] (First diffusion inhibition layer, second diffusion inhibition layer)

[0091] In order to suppress the diffusion of anisotropic pigments or anisotropic polymeric liquid crystal compounds (hereinafter, both are sometimes referred to as "isotropic pigments") in the linear polarizing layer 31 to other layers, a first diffusion suppression layer 35 and a second diffusion suppression layer 36 may be used.

[0092] The first diffusion suppression layer 35 is disposed between the transparent resin film 15 and the circular polarizer 40, and the second diffusion suppression layer constitutes the circular polarizer 40 and is disposed between the linear polarizer 31 and the first phase difference layer 33. When the optical laminate 2 having the first diffusion suppression layer 35 and / or the second diffusion suppression layer 36 is assembled in a display device, the time-dependent reduction in optical properties caused by the diffusion of anisotropic pigments can be suppressed.

[0093] The first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 are not particularly limited as long as they are layers capable of inhibiting the diffusion of anisotropic pigments. Examples of the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 are layers formed from resin compositions containing water-soluble polymers and layers formed from curing compositions containing active energy line curing resins.

[0094] Because the polarity of water-soluble polymers differs significantly from that of anisotropic pigments, the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 formed from a resin composition containing water-soluble polymers can inhibit the diffusion of anisotropic pigments. Examples of water-soluble polymers that can form the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 include: polyacrylamide polymers; polyvinyl alcohol, ethylene-vinyl alcohol copolymers, (meth)acrylic acid or its anhydride-vinyl alcohol copolymers, etc.; carboxyvinyl polymers; polyvinylpyrrolidone; starches; sodium alginate; polyethylene oxide polymers, etc. These polymers can be used alone or in combination of two or more.

[0095] When the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 are formed of a resin composition containing a water-soluble polymer, the content of the water-soluble polymer in the layer is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more.

[0096] In order to introduce a crosslinking structure that enhances the density of the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 and improves the function of inhibiting the diffusion of anisotropic pigments, the resin composition containing the water-soluble polymer may contain a crosslinking agent. Examples of crosslinking agents include: ionic crosslinking agents such as glyoxylates, water-soluble crosslinking agents such as epoxy crosslinking agents; hydrophobic crosslinking agents such as isocyanate crosslinking agents, polyaldehyde crosslinking agents such as glyoxal and glyoxal derivatives, and metal compound crosslinking agents such as zirconium chloride and titanium lactate. The content of the crosslinking agent in the resin composition containing the water-soluble polymer may be, for example, 0.1 parts by mass or more, 1 part by mass or more, 10 parts by mass or more, or less than 100 parts by mass, 50 parts by mass or less, or 30 parts by mass or less, relative to 100 parts by mass of the water-soluble polymer.

[0097] A resin composition containing a water-soluble polymer is prepared into a solution by dissolving the water-soluble polymer in a solvent. The solvent can be selected according to the type of water-soluble polymer, such as water, alcohol, or a mixture of water and alcohol, with water being preferred.

[0098] The concentration of solid components in a resin composition containing a water-soluble polymer may be, for example, 1% by mass or more, 2% by mass or more, 50% by mass or less, or 30% by mass or less.

[0099] In addition to the water-soluble polymer, crosslinking agent, and solvent, the resin composition containing the water-soluble polymer may also contain additives such as preservatives and leveling agents. The content of additives in the resin composition containing the water-soluble polymer, for example, may be 10% by mass or less, or 5% by mass or less, relative to the solid content of the resin composition.

[0100] The first diffusion inhibition layer 35 and the second diffusion inhibition layer 36, formed from a resin composition comprising a water-soluble polymer, can be formed by coating the resin composition onto the surfaces on which the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 are formed (e.g., the linear polarizing layer 31 of the circular polarizers 30 and 40) and then drying them. The drying process can be performed, for example, by blowing hot air. The drying temperature can be, for example, 40°C or higher, 60°C or lower, or 100°C or lower, and the drying time can be, for example, 10 seconds or more or 600 seconds or less.

[0101] Since the active energy line curable resin can be highly polymerized, the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 formed by the curable composition containing the active energy line curable resin can inhibit the diffusion of anisotropic pigments. Examples of curable compositions include cationic polymeric curable compositions containing cationic polymeric compounds as curable compounds, free radical polymeric curable compositions containing free radical polymeric compounds as curable compounds, and curable compositions containing a mixture of cationic polymeric compounds and free radical polymeric compounds. Specific examples of cationic polymeric compounds include epoxy compounds having one or more epoxy groups in the molecule, oxetane compounds having one or more oxetane rings in the molecule, and vinyl compounds. Specific examples of free radical polymeric compounds include (meth)acrylic acid compounds having one or more (meth)acrylic groups in the molecule, and vinyl compounds. The curing composition system may contain one or more cationic polymeric compounds and / or one or more free radical polymeric compounds.

[0102] Cationic polymeric compounds, which are the main components of cationic polymeric curable compositions, refer to compounds or oligomers that undergo cationic polymerization and harden by irradiation or heating with active energy lines such as ultraviolet light, visible light, electron beams, and X-rays. Examples include epoxy compounds, oxetane compounds, and vinyl compounds. Among these, epoxy compounds are preferred.

[0103] An epoxy compound is a compound having one or more (preferably two or more) epoxy groups within its molecule. An epoxy compound may be used alone or in combination with two or more types. Examples of epoxy compounds include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. From the viewpoints of weather resistance, curing speed, and adhesion, epoxy compounds comprising alicyclic epoxy compounds and / or aliphatic epoxy compounds are preferred.

[0104] When the curing composition contains an epoxy compound as a cationic polymerizable compound, the content of the epoxy compound relative to 100 parts by mass of the solid component of the curing composition may be 10 parts by mass or more, 15 parts by mass or more, 20 parts by mass or more, or 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less.

[0105] When the total amount of curing compounds contained in the curing composition is set to 100% by mass, the content of cationic polymeric compounds (the total content of these when there are two or more cationic polymeric compounds) can be 50% by mass or more, or 60% by mass or more, or 70% by mass or more. Furthermore, the curing composition may further include polymer components (thermoplastic resins, etc.).

[0106] When the curing component contains a cationic polymerizable compound, it is preferable to include a photocationic polymerization initiator. A photocationic polymerization initiator is one that generates cationic species or Lewis acids by irradiation with active energy lines such as visible light, ultraviolet light, X-rays, or electron beams, thereby initiating the polymerization reaction of the cationic curing compound. Since the photocationic polymerization initiator uses light as a catalyst, it maintains excellent stability and workability even when mixed with a photocationic curing compound. Examples of compounds that generate cationic species or Lewis acids by irradiation with active energy lines include, for example, onium salts such as aromatic monium salts and aromatic strontium salts, aromatic diazonium salts, and iron-aromatic complexes.

[0107] Photocationic polymerization initiators can be used alone or in combination with two or more. Among them, aromatic strontium salts are suitable for use because they also have ultraviolet absorption characteristics in the wavelength region around 300 nm, thus exhibiting excellent curing properties and producing cured products with good mechanical strength or adhesion strength.

[0108] Relative to 100 parts by mass of the solid component of the curing compound, the content of the photocationic polymerization initiator in the curing composition can be 1 part by mass or more, or 2 parts by mass or more, or 10 parts by mass or less, or 8 parts by mass or less. If the content of the photocationic polymerization initiator is within the above range, the cationic polymerizable compound can be sufficiently cured, and high mechanical strength or adhesion strength can be imparted to the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36.

[0109] The curing composition containing cationic polymeric compounds may also contain more free radical polymeric compounds to form a mixed curing composition. By using free radical polymeric compounds, it is expected to improve the hardness or mechanical strength of the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36, and it is easier to adjust the viscosity or curing speed of the curing composition.

[0110] Free radical polymerizable compounds refer to compounds or oligomers that undergo free radical polymerization and harden under the irradiation or heating of active energy lines such as ultraviolet light, visible light, electron beams, and X-rays. Specifically, compounds containing vinyl unsaturated bonds can be listed. Compounds containing vinyl unsaturated bonds include (meth)acrylic acid compounds with one or more (meth)acrylic acid groups in the molecule, as well as vinyl compounds such as styrene, styrene sulfonic acid, vinyl acetate, vinyl propionate, and N-vinyl-2-pyrrolidone. Among these, (meth)acrylic acid compounds are preferred free radical polymerizable compounds.

[0111] (Meth)acrylic acid compounds are compounds having at least one (meth)acrylic acid group in the molecule, and can be monomers, oligomers, or polymers. Examples of (meth)acrylic acid compounds include: monofunctional (meth)acrylate compounds, polyfunctional (meth)acrylate compounds, and other (meth)acrylate compounds; polyfunctional urethane (meth)acrylate compounds, and other urethane (meth)acrylate compounds; epoxy (meth)acrylate compounds, and other epoxy (meth)acrylate compounds; carboxyl-modified epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, etc. A single (meth)acrylic acid compound may be used alone, or two or more may be used in combination.

[0112] Examples of (meth)acrylate compounds include monofunctional (meth)acrylate compounds having one (meth)acryloxy group in the molecule and polyfunctional (meth)acrylate compounds having two or more (meth)acryloxy groups in the molecule.

[0113] When using a polyfunctional (meth)acrylate compound, the crosslinking density of the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 can be adjusted by controlling the molecular weight between crosslinking points and the number of crosslinking points of the compound. More specifically, the smaller the molecular weight between crosslinking points, the higher the crosslinking density; and the more crosslinking points, the denser the crosslinking density, which can improve the masking properties of the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 for anisotropic pigments.

[0114] The term "urethane (meth)acrylate compound" generally refers to a reaction product of isocyanate compounds, polyol compounds, and (meth)acrylate compounds, with polyfunctional urethane (meth)acrylate compounds having two or more (meth)acryloxy groups in the molecule being preferred. Polyfunctional urethane (meth)acrylate compounds are advantageous from the viewpoint of enhancing the function of the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 in inhibiting the diffusion of anisotropic pigments, as they can form cross-linked structures, and can impart appropriate styrene properties. The number of functional groups in the polyfunctional urethane (meth)acrylate compound is preferably 2 or more and 5 or less.

[0115] Epoxy (meth)acrylate compounds can be obtained, for example, by the addition reaction of polyglycidyl ether with (meth)acrylic acid, and examples include polyfunctional epoxy (meth)acrylates having at least two (meth)acryloxy groups in the molecule. Polyester (meth)acrylate compounds can be examples of compounds having an ester bond and at least two (meth)acrylyl groups (typically (meth)acryloxy) groups in the molecule.

[0116] When the curing composition contains a free radical polymerizable compound, it is preferable to include a polyfunctional (meth)acrylate compound as a free radical polymerizable compound. In this case, relative to 100 parts by mass of the solid content of the curing composition, the content of the polyfunctional (meth)acrylate compound may be, for example, 50 parts by mass or more, 60 parts by mass or more, 70 parts by mass or more, or 100 parts by mass or less, 95 parts by mass or less, or 90 parts by mass or less.

[0117] When the curable composition contains a free radical polymerizable compound, it is preferable that it contains a polyfunctional (meth)acrylate compound and a polyfunctional urethane (meth)acrylate compound as free radical polymerizable compounds. In this case, the content ratio of the polyfunctional (meth)acrylate compound to the urethane (meth)acrylate compound (mass ratio of polyfunctional (meth)acrylate compound to urethane (meth)acrylate compound) can be from 95:5 to 50:50, or from 90:10 to 70:30.

[0118] When the curing component contains a free radical polymerizable compound, it is preferable to contain a photoradioactive polymerization initiator. A photoradioactive polymerization initiator initiates the polymerization reaction of the free radical polymerizable compound by irradiation with active energy lines such as visible light, ultraviolet light, X-rays, or electron beams. A photoradioactive polymerization initiator may be used alone or in combination with two or more.

[0119] Specific examples of photoradical polymerization initiators include: acetophenone, 3-methylacetophenone, benzyl dimethyl acetal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morphofolinylpropane-1-one, and acetobenzene-based initiators such as 2-hydroxy-2-methyl-1-phenylpropane-1-one; benzophenone, 4-chlorobenzophenone, and 4,4'-diaminodibenzophenone. Benzophenone, etc., is a starting agent; alkylphenols such as 2,2-dimethoxy-1,2-diphenylethane-1-one and 1-hydroxy-cyclohexyl-phenyl-one are starting agents; benzoin ethers such as benzoin propyl ether and benzoin ethyl ether are starting agents; thioxanthraquinones such as 4-isopropylthioxanthraquinone are starting agents; acetylsine oxides such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide are starting agents; others include xanthraquinones, fumonisins, camphorquinone, benzaldehyde, anthraquinones, etc.

[0120] Relative to 100 parts by mass of the solid component of the polymerizable compound, the content of the photoradical polymerization initiator in the curing composition can be 1 part by mass or more, or 2 parts by mass or more, or 10 parts by mass or less, or 8 parts by mass or less. If the content of the photoradical polymerization initiator is within the above range, the polymerization initiation energy is fully manifested and the curing property is improved. At the same time, because the photoradical polymerization initiator is not easy to remain, it is easy to suppress the decrease in visible light transmittance, etc.

[0121] The first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 formed from the curable composition are formed by coating the curable composition onto the surfaces on which the first diffusion inhibition layer 35 and the second diffusion inhibition layer 36 are formed (e.g., the linear polarizing layer 31 of the circular polarizers 30 and 40), and then irradiating the active energy lines to harden the curable composition. To adjust the viscosity to suit the coating method, the curable composition may contain an organic solvent or may be substantially solvent-free (solvent-free). "Substantially solvent-free" means that the unavoidable mixing of solvents is not excluded.

[0122] Any solvent system can dissolve the components constituting the hardening composition. Examples include: water; alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl pentyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvent systems can be used alone or in combination of two or more.

[0123] The curing composition system may contain additives such as cationic polymerization accelerators, photosensitizers, ion scavengers, antioxidants, chain movers, tackifiers, thermoplastic resins, fillers, flow modifiers, plasticizers, defoamers, antistatic agents, and leveling agents as needed.

[0124] Examples of active energy beams used for curing curable compositions include visible light, ultraviolet light, X-rays, or electron beams, with ultraviolet light being preferred. Examples of light sources for active energy beams include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten filament lamps, gallium lamps, excimer lasers, LED light sources that emit light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

[0125] The intensity of ultraviolet (UV) irradiation is typically between 10 mW / cm² and 3000 mW / cm². A suitable UV irradiation intensity is within the wavelength range effective for activating photopolymerization initiators. The irradiation time is typically 0.1 seconds or more, but can be 1 second or more, 5 seconds or more, or 10 seconds or more; it can also be less than 10 minutes, 5 minutes or less, 3 minutes or less, or 1 minute or less. The cumulative UV light intensity can be 10 mJ / cm² or more, 50 mJ / cm² or more, 100 mJ / cm² or more; it can also be less than 3000 mJ / cm², 2000 mJ / cm² or less, or 1000 mJ / cm².

[0126] The thicknesses of the first diffusion suppression layer 35 and the second diffusion suppression layer 36 are preferably 5 μm or less, or 4 μm or less, or 3 μm or less, or 0.1 μm or more, or 0.3 μm or more, or 0.5 μm or more. By ensuring that the thicknesses of the first diffusion suppression layer 35 and the second diffusion suppression layer 36 are within the above-mentioned ranges, the diffusion of anisotropic pigments in the linear polarizing layer 31 to other layers can be effectively suppressed.

[0127] (First bonding layer, second bonding layer, third bonding layer, bonding layer)

[0127] The first adhesive layer 25, the second adhesive layer 32, the third adhesive layer 37, and the adhesive layer are adhesive layers or bonding agent layers. The adhesive layer can be formed using the adhesive composition described in the first adhesive layer 21 and the second adhesive layer 12 or an active energy line curing type adhesive composition. The thickness of the adhesive layer can be set within the range described in the first adhesive layer 21 and the second adhesive layer 12.

[0128] The adhesive layer can be formed by curing the curing component in the adhesive composition. The adhesive composition used to form the adhesive layer is an adhesive other than a pressure-sensitive adhesive, such as water-based adhesives and active energy line curing adhesives.

[0129] Examples of water-based adhesives include adhesives that dissolve or disperse polyvinyl alcohol resin 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.

[0130] Examples of active energy line curing adhesives include solvent-free active energy line curing adhesives that are cured by irradiation with active energy lines such as ultraviolet light, visible light, electron beams, and X-rays. By using solvent-free active energy line curing adhesives, the adhesion between layers can be improved.

[0131] From the perspective of exhibiting good adhesion, it is preferable that the active energy line curing adhesive contains either or both of a cationic polymerizable curing compound and a free radical polymerizable curing compound. The active energy line curing adhesive may further contain a cationic polymerization initiator, such as a photocationic polymerization initiator, or a free radical polymerization initiator, for initiating the curing reaction of the aforementioned curing compound.

[0132] Examples of cationic polymerizable curing compounds include: alicyclic epoxy compounds having epoxy groups bonded to alicyclic rings; polyfunctional aliphatic epoxy compounds having two or more epoxy groups but no aromatic rings; monofunctional epoxy groups having one epoxy group (excluding those included in alicyclic epoxy compounds); polyfunctional aromatic epoxy compounds having two or more epoxy groups and aromatic rings; oxetane compounds having one or more oxetane rings in the molecule; and combinations thereof.

[0133] Examples of curing compounds with free radical polymerizability include (meth)acrylic acid compounds (compounds having one or more (meth)acrylic acid groups in the molecule), other vinyl compounds with double bonds that have free radical polymerizability, or combinations thereof.

[0134] The active energy line curing adhesive may contain sensitizers such as photosensitizers as needed. By using sensitizers, reactivity is increased, and the mechanical strength or adhesive strength of the adhesive layer can be further improved. Known sensitizers are suitable for use. When preparing the sensitizer, the amount prepared is preferably in the range of 0.1 to 20 parts by weight relative to 100 parts by weight of the total active energy line curing adhesive.

[0135] Active energy line curing adhesives may contain additives such as ion traps, antioxidants, chain movers, tackifiers, thermoplastic resins, fillers, flow modifiers, plasticizers, defoamers, antistatic agents, leveling agents, and solvents as needed.

[0136] When using an active energy line curing adhesive, active energy lines such as ultraviolet light, visible light, electron beams, and X-rays can be irradiated to harden the adhesive coating layer and form an adhesive layer. Ultraviolet light is preferred as the active energy line system. The light source system can be a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, or a metal halide lamp.

[0137] The thickness of the adhesive layer can be 0.1 μm or more, or 0.5 μm or more, or 10 μm or less, or 5 μm or less.

[0137] [Example]

[0138] Hereinafter, embodiments will be shown to illustrate the present invention in more detail, but the present invention is not limited to these embodiments. In the embodiments and comparative examples, "%" and "parts" are "mass %" and "parts by mass" unless otherwise specified.

[0139] [Preparation of surface protective film (1)]

[0139] (Preparation of adhesive composition (1))

[0139] In a reaction apparatus equipped with a stirrer, thermometer, reflux cooling, and nitrogen inlet tube, nitrogen gas was introduced to replace the air in the reaction apparatus. Then, 93 parts of 2-ethylhexyl acrylate, 5.5 parts of 8-hydroxyoctyl acrylate, 1.5 parts of acrylic acid, and 60 parts of solvent (ethyl acetate) were added to the reaction apparatus. After this, 0.1 parts of azobisisobutyronitrile (AIB) were added dropwise over 2 hours as a polymerization initiator, and the reaction was carried out at 65°C for 6 hours to obtain an acrylic resin solution (1). The weight average molecular weight of the acrylic polymers contained in the acrylic resin solution (1) is approximately 500,000, converted from standard polystyrene obtained by gel permeation chromatography.

[0140] To 100 parts of acrylic polymer contained in acrylic resin solution (1), 2.0 parts of 1-octylpyridinium dodecylbenzene sulfonate as an antistatic agent were added and stirred, and then 1.5 parts of CORONATE HX (a triisocyanate of hexamethylene diisocyanate compound: manufactured by TOSOH Corporation) were added and stirred to obtain adhesive composition (1).

[0141] (Preparation of the surface protective film (1) attached to the separation membrane)

[0141] After coating an adhesive composition (1) onto a 15 μm thick separation membrane made of polyethylene terephthalate (PET) film coated with polysiloxane resin, the membrane is dried at 90°C to remove the solvent, forming a second adhesive layer with a thickness of 15 μm after drying. Subsequently, for the first substrate film, a 75 μm thick polyethylene terephthalate (PET) film with one side treated with antistatic and antifouling methods is used. The side of this PET film opposite to the side treated with antistatic and antifouling methods is deposited onto the second adhesive layer to obtain a surface protective film (1) with the separation membrane attached. The layer structure of the surface protective film (1) with the separation membrane attached is surface protective film (1) (first substrate film / second adhesive layer) / separation membrane.

[0142] [Preparation of Surface Protective Film (2)]

[0142] Regarding the first substrate film, except for the use of a 38 μm thick polyethylene terephthalate (PET) film with one side treated with antistatic and antifouling treatment, the rest are prepared in the same order as the surface protective film (1) with the separation film, thus obtaining the surface protective film (2) with the separation film. The layer structure of the surface protective film (2) with the separation film is surface protective film (2) (first substrate film / second adhesive layer) / separation film.

[0143] [Fabrication of a circular polarizer with a diffusion suppression layer]

[0144] (Preparation of aqueous solutions of water-soluble polymers)

[0144] A water-soluble polymer composed of the following structural units is obtained according to the following synthetic reaction mechanism.

[0144]

[0145] In 400g of dimethyl sulfoxide, 20g of polyvinyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) with a molecular weight of 1000, 0.55mg of N,N-dimethyl-4-aminopyridine as a nucleophile, and 4.6g of triethylamine were dissolved and stirred while the mixture was heated to 60°C. Afterward, a solution containing 10.5g of methacrylic anhydride was added dropwise to 50g of dimethyl sulfoxide over 1 hour, and the mixture was heated and stirred at 60°C for 14 hours to allow the reaction to proceed. After cooling the resulting reaction solution to room temperature, 481g of methanol was added to the reaction solution and stirred until completely mixed, thereby adjusting the ratio (by mass) of the reaction solution to methanol to 1:1. 1500mL of acetone was slowly added to this solution to crystallize the water-soluble polymer by crystallization. The resulting solution containing white crystals was filtered, thoroughly washed with acetone, and then dried under vacuum to obtain 20.2g of the water-soluble polymer. The obtained water-soluble polymer is dissolved in water to prepare a 3% by mass aqueous solution of the water-soluble polymer.

[0146] (Modulation of components for forming a photooriented layer)

[0146] The following components are mixed and the resulting mixture is stirred at 80°C for 1 hour to obtain a composition for forming a photooriented layer.

[0146] ‧Photooriented polymer [The polymer shown in the following formula as disclosed in Japanese Patent Application Publication No. 2013-33249 (quantity average molecular weight: about 28,200, Mw / Mn: 1.82)]: 2 parts

[0146]

[0146] ‧ Solvent (o-xylene): 98 parts

[0147] (Modification of Component 1)

[0147] The first composition is obtained by mixing the following components and stirring at 80°C for 1 hour.

[0147] The azo pigment with the following formula described in the example of Japanese Patent Application Publication No. 2013-101328 is used in the pigment system with absorption anisotropy.

[0147] ‧The polymeric liquid crystal compound (A1) shown in the following formula: 75 parts

[0147]

[0147] ‧The polymeric liquid crystal compound (A2) shown in the following formula: 25 parts

[0147]

[0147] ‧A pigment (azo pigment 1) having the absorption anisotropy shown in the following formula: 2.5 parts

[0147]

[0147] ‧A pigment (azo pigment 2) having the absorption anisotropy shown in the following formula: 2.5 parts

[0147]

[0147] ‧A pigment (azo pigment 3) having the absorption anisotropy shown in the following formula: 2.5 parts

[0147]

[0147] ‧Polymerization initiator [2-Dimethylamino-2-benzyl-1-(4-morphofolinylphenyl)butane-1-one (IRGACURE 369; manufactured by Ciba Specialty Chemicals, Inc.)]: 6 parts

[0147] ‧Leveling agent [polyacrylate compound (BYK-361N; manufactured by BYK-Chemie)]: 1.2 parts

[0147] ‧ Solvent [o-xylene]: 250 parts

[0148] (Modification of the second component)

[0148] The second composition is obtained by mixing the following components and stirring at 80°C for 1 hour.

[0148] ‧The polymeric liquid crystal compound (X1) shown in the following formula: 100 parts

[0148]

[0148] ‧The polymeric liquid crystal compound (X2) shown in the following formula: 33 parts

[0148]

[0148] ‧Polymerization initiator [2-Dimethylamino-2-benzyl-1-(4-morphofolinylphenyl)butane-1-one (IRGACURE (registered trademark) 369; manufactured by BASF JAPAN)]: 8 parts

[0148] ‧Leveling agent [polyacrylate compound (BYK-361N; manufactured by BYK-Chemie)]: 0.1 parts

[0148] ‧Reaction additive (LALOMER LR9000; manufactured by BASF JAPAN): 6.7 parts

[0148] ‧ Solvent (cyclopentanone): 546 parts

[0148] ‧ Solvent [N-methylpyrrolidone]: 364 parts

[0149] (Modulation of components for orientation layer formation)

[0149] A composition for oriented layer formation was prepared by adding 2-butoxyethanol to SUNEVER SE-610 (manufactured by Nissan Chemical Industries, Ltd.), a commercially available oriented polymer. The solid content of the oriented layer formation composition is 1%, and the solvent content is 99%, relative to the total amount of the composition. The solid content of the oriented polymer was calculated from the concentration stated in the shipping specification.

[0150] (Modification of the third component)

[0150] Mix the following ingredients and stir at 80°C for 1 hour, then cool to room temperature to obtain composition 3. The content ratios shown below are the content ratios of each ingredient relative to the total amount of composition 3.

[0150] ‧The polymeric liquid crystal compound shown in the following formula [LC242; manufactured by BASF]: 19.2%

[0150]

[0150] ‧Polymerization initiator (IRGACURE 907; manufactured by BASF JAPAN): 0.5%

[0150] ‧Leveling agent [BYK CHEMIE JAPAN; BYK361N]: 0.1%

[0150] ‧Reaction additive (Laromer LR-9000; manufactured by BASF JAPAN): 1.1%

[0150] ‧ Solvent [Propylene glycol 1-monomethyl ether 2-acetate (PGMEA)]: 79.1%

[0151] (Fabrication of a linear polarizing layer with diffusion suppression layer attached)

[0151] On the release-treated surface of the release polyethylene terephthalate (PET) film (UNITIKA Co., Ltd. "FF-50", single-sided release-treated PET film, substrate thickness: 50μm), the above-prepared 3% by mass aqueous solution of water-soluble polymer is coated with a rod coater and dried at 100°C for 2 minutes to form a first diffusion inhibition layer with a thickness of 2μm composed of a film of water-soluble polymer.

[0152] After plasma treatment of the surface of the first diffusion inhibition layer, the above-modified composition for forming the photo-orientation layer is coated using a bar coater to form a coated film. The coated film is dried at 100°C for 2 minutes to remove the solvent and form a dried film. The dried film is irradiated with polarized ultraviolet light at an intensity of 20 mJ / cm2 (313 nm reference) to impart orientation restraint force, forming a first orientation layer with a thickness of 50 nm.

[0153] The first composition prepared above is coated onto the first orientation layer using a rod coater to form a coated film. Furthermore, by drying at 110°C for 2 minutes to remove the solvent and transfer the polymeric liquid crystal compound phase into a liquid phase, the film is cooled to room temperature and the polymeric liquid crystal compound phase is transferred into a lamellar liquid crystal state. Subsequently, the obtained dried film is irradiated with ultraviolet light at 1000 mJ / cm² (365 nm reference) using a high-pressure mercury lamp, and polymerization is performed while maintaining the lamellar liquid crystal state of the polymeric liquid crystal compound contained in the dried film to form a first hardened layer with a thickness of 3 μm.

[0154] After applying plasma treatment to the first hardened layer, a 3% by mass aqueous solution of the prepared water-soluble polymer is coated using a rod coater, and dried at 100°C for 2 minutes to form a second diffusion inhibition layer with a thickness of 2 μm composed of a water-soluble polymer film, thus obtaining a linear polarizing layer with a diffusion inhibition layer. The layer structure of the linear polarizing layer with a diffusion inhibition layer is release PET film / first diffusion inhibition layer / linear polarizing layer (first orientation layer / first hardened layer) / second diffusion inhibition layer.

[0155] (Fabrication of the first phase difference layer with substrate layer attached)

[0155] A corona treatment was applied to the surface opposite to the release treatment surface of a release polyethylene terephthalate (PET) film (UNITIKA Co., Ltd. "FF-50", single-sided release-treated PET film, substrate thickness: 50 μm). The aforementioned photo-alignment layer forming composition was coated onto the corona-treated film using a rod coater, dried at 120°C for 2 minutes, and then cooled to room temperature to form a dried film. The dried film was then irradiated with polarized ultraviolet light at an intensity of 100 mJ / cm² (313 nm reference) to form a second alignment layer with a thickness of 100 nm.

[0156] The first composition prepared above is coated onto the second alignment layer using a rod coater to form a coated film. Then, after heating and drying at 120°C for 2 minutes, it is cooled to room temperature to obtain a dried film. Subsequently, on this dried film, a second hardened layer with a thickness of 2 μm is formed by irradiating it with ultraviolet light at an exposure intensity of 1000 mJ / cm² (365 nm reference), causing the polymerizable liquid crystal compound to be horizontally aligned relative to the surface of the first retardation layer. This yields the first retardation layer of the substrate layer. The layer structure of the first retardation layer of the substrate layer is release PET film / first retardation layer (second alignment layer / second hardened layer).

[0157] (Fabrication of the second phase difference layer with substrate layer)

[0157] The surface of a cyclic olefin polymer (COP) film (ZF-14, manufactured by ZEON Corporation, Japan) was treated once using a corona treatment apparatus at an output of 0.3 kW and a treatment speed of 3 m / min. The prepared orientation layer formation composition was then applied to the corona-treated surface using a rod coater and dried at 90°C for 1 minute to obtain a third orientation layer. The thickness of the third orientation layer was measured using a laser microscope and found to be 1 μm.

[0158] The prepared third composition is coated onto the third alignment layer using a rod coater to form a coating film. Then, after drying at 90°C for 1 minute, a third hardened layer with a thickness of 500 nm is formed by irradiating with ultraviolet light (cumulative light intensity at a wavelength of 365 nm in a nitrogen environment: 1000 mJ / cm²) using a high-pressure mercury lamp. This hardens the polymeric liquid crystal compound to a state perpendicular to the surface of the second retardation layer, thus obtaining the second retardation layer with a substrate layer. The layer structure of the second retardation layer with the substrate layer is COP film / second retardation layer (third alignment layer / third hardened layer).

[0159] (Preparation of adhesive composition)

[0159] After mixing the components shown below, degassing is performed to prepare a cationic polymeric adhesive layer composition.

[0159] The cationic polymerization initiator was prepared as a 50% by mass solution of propyl carbonate, and its solid content is shown.

[0159] ‧1,6-Hexanediol diglycidyl ether (EX-212L, manufactured by Nagase Chemtex Inc.): 25 parts

[0159] ‧4-Hydroxybutylvinyl ether: 10 parts

[0159] ‧Bisphenol F type epoxy resin (EXA-830CRP, manufactured by DIC Corporation): 65 parts

[0159] ‧Catonic polymerization initiator (CPI-100P, manufactured by SUNAPRO Co., Ltd., 50% by mass solution): 3 parts

[0160] (Fabrication of a circular polarizer with a diffusion suppression layer)

[0160] A linear polarizing layer and a first phase retardation layer are bonded together with a second bonding layer (a 5μm thick pressure-sensitive adhesive layer manufactured by LINTEC) between the second diffusion suppression layer on the second diffusion suppression layer side and the first phase retardation layer side of the substrate layer, such that the angle between the absorption axis of the linear polarizing layer and the slow axis of the first phase retardation layer is 45°, thereby obtaining a laminate of the linear polarizing layer and the first phase retardation layer. The layer structure of this laminate is: release PET film / first diffusion suppression layer / linear polarizing layer (first orientation layer / first hardening layer) / second diffusion suppression layer / second bonding layer (adhesive layer) / first phase retardation layer (second hardening layer / second orientation layer) / release PET film.

[0161] A corona treatment is applied to the surface of the second phase retardation layer of the substrate layer obtained above. The surface of the laminate (the laminate of the linear polarizing layer and the first phase retardation layer) exposed on the side of the first phase retardation layer, which is peeled off from the above-obtained laminate, and the corona-treated surface of the second phase retardation layer of the substrate layer are bonded together with the above-prepared adhesive composition, and irradiated with ultraviolet light at an exposure dose of 500 mJ / cm2 (365 nm reference) using an ultraviolet irradiation device (SPOT CURE SP-7, manufactured by USHIO Electric Co., Ltd.). Thereby, a third bonding layer with a thickness of 2 μm is formed from the adhesive composition as an adhesive layer, and a circular polarizer with a diffusion suppression layer is obtained. The layer structure of a circular polarizer with a diffusion suppression layer is: release PET film / first diffusion suppression layer / linear polarizing layer (first alignment layer / first hardening layer) / second diffusion suppression layer / second bonding layer (adhesive layer) / first retardation layer (second hardening layer / second alignment layer) / third bonding layer (adhesive layer) / second retardation layer (third hardening layer / third alignment layer) / COP film. In the circular polarizer with a diffusion suppression layer, the linear polarizing layer to the second retardation layer constitute the circular polarizer.

[0162] [Preparation of the release film for the first adhesive layer]

[0162] (Preparation of adhesive composition (2))

[0162] In a reactor equipped with a cooling pipe, a nitrogen inlet pipe, a thermometer, and a stirrer, a mixed solution of 81.8 parts acetone, 98.4 parts butyl acrylate, 0.6 parts acrylic acid, and 1.0 parts 2-hydroxyethyl acrylate was packed. Nitrogen was used to replace the air in the apparatus, eliminating the presence of oxygen, and the internal temperature was raised to 55°C. After this, a solution containing 0.14 parts azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts acetone was added. One hour after adding the polymerization initiator, the concentration of acrylic resin other than the monomer was adjusted to 35%. Acetone was continuously added to the reactor at an addition rate of 17.3 parts / hr, while maintaining the internal temperature at 54 to 56°C for 12 hours. Finally, ethyl acetate was added to adjust the concentration of acrylic resin to 20%, thereby obtaining an acrylic resin solution (2).

[0163] 100 parts of mixed acrylic resin solution (2) (non-volatile component amount), 0.5 parts of isocyanate compound (CORONATE L, ethyl acetate solution of trimethylolpropane adduct of toluene diisocyanate (solid component concentration 75%) (manufactured by TOSOH Co., Ltd.)), 0.5 parts of silicate compound (KBM-403, 3-epoxypropoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)), and ethyl acetate was added to make the solid component concentration 10% to obtain adhesive composition (2).

[0164] (Preparation of the release film for the first adhesive layer)

[0164] Using a release-treated polyethylene terephthalate film (38 μm thick) as a release film, an adhesive composition (2) was coated onto its release-treated surface using a thin coater to a thickness of 15 μm after drying. The coated layer was dried at 100°C for 1 minute to obtain a release film with a first adhesive layer. Subsequently, a release-treated polyethylene terephthalate (PET) film (38 μm thick) serving as the release film was laminated onto the first adhesive layer and cured for 7 days at 23°C and 50% RH to obtain a release film with a first adhesive layer. The layer structure of the release film with the first adhesive layer is release film / first adhesive layer / release film.

[0165] 〔Example 1〕

[0165] Corona treatment was applied to the exposed surfaces of a 13 μm thick cyclic olefin polymer (COP) film (ZF-14, manufactured by ZEON Corporation, Japan) serving as a transparent resin film, and the circular polarizer with the diffusion suppression layer obtained above, after the release PET film was peeled off. The corona-treated surfaces were then bonded together with the aforementioned prepared adhesive composition in between, and irradiated with ultraviolet light at an exposure dose of 500 mJ / cm² (365 nm reference) using an ultraviolet irradiation device (SPOT CURE SP-7, manufactured by USHIO Electric Co., Ltd.). This formed a first bonding layer with a thickness of 2 μm, serving as the adhesive layer, from the adhesive composition, thus obtaining a laminate of the transparent resin film and the circular polarizer. The laminated structure consists of a transparent resin film (COP film) / a first bonding layer (adhesive layer) / a first diffusion inhibition layer / a linear polarizing layer (first orientation layer / first curing layer) / a second diffusion inhibition layer / a second bonding layer (adhesive layer) / a first phase retardation layer (second curing layer / second orientation layer) / a third bonding layer (adhesive layer) / a second phase retardation layer (third curing layer / third orientation layer) / COP film.

[0166] The surface exposed by peeling off the COP film on the second phase difference layer side 2 of the above-obtained laminate (the laminate of transparent resin film and circular polarizer) is bonded to the surface exposed by peeling off one of the release films from the release film with the first adhesive layer obtained above, to obtain a laminate (a laminate of transparent resin film, circular polarizer, first adhesive layer, and release film). The surface exposed by peeling off the release film from the surface protective film (1) with the release film obtained above is bonded to the transparent resin film surface of the laminate to obtain an optical laminate (1). The layer structure of the optical laminate (1) is as follows: surface protective film (1) (first substrate film / second adhesive layer) / transparent resin film (COP film) / first bonding layer (adhesive layer) / first diffusion inhibition layer / linear polarization layer (first orientation layer / first hardening layer) / second diffusion inhibition layer / second bonding layer (adhesive layer) / first phase difference layer (second hardening layer / second orientation layer) / third bonding layer (adhesive layer) / second phase difference layer (third hardening layer / third orientation layer) / first adhesive layer / release film.

[0167] 〔Example 2〕

[0167] Optical laminate (2) was obtained in the same manner as in Example 1, except that the surface protective film (2) with the separation film obtained above was used instead of the surface protective film (1) with the separation film. The layer structure of the optical laminate (2) is: surface protective film (2) (first substrate film / second adhesive layer) / transparent resin film (COP film) / first bonding layer (adhesive layer) / first diffusion inhibition layer / linear polarization layer (first orientation layer / first hardening layer) / second diffusion inhibition layer / second bonding layer (adhesive layer) / first phase difference layer (second hardening layer / second orientation layer) / third bonding layer (adhesive layer) / second phase difference layer (third hardening layer / third orientation layer) / first adhesive layer / release film.

[0168] 〔Example 3〕

[0168] Optical laminate (3) was obtained in the same manner as in Example 1, except that a 20 μm thick triacetyl cellulose (TAC) membrane (KC2CT, manufactured by KONICA MINOLTA Co., Ltd.) was used instead of the cyclic olefin polymer (COP) membrane used as the transparent resin membrane. The layer structure of the optical laminate (3) is as follows: surface protective film (1) (first substrate film / second adhesive layer) / transparent resin film (TAC film) / first bonding layer (adhesive layer) / first diffusion inhibition layer / linear polarization layer (first orientation layer / first hardening layer) / second diffusion inhibition layer / second bonding layer (adhesive layer) / first phase retardation layer (second hardening layer / second orientation layer) / third bonding layer (adhesive layer) / second phase retardation layer (third hardening layer / third orientation layer) / first adhesive layer / release film.

[0169] 〔Example 4〕

[0169] Opto-laminated composite (4) was obtained in the same manner as in Example 2, except that a 20 μm thick triacetyl cellulose (TAC) membrane (KC2CT, manufactured by KONICA MINOLTA Co., Ltd.) was used instead of the cyclic olefin polymer (COP) membrane used as the transparent resin membrane. The layer structure of the optical laminate (4) is as follows: surface protective film (2) (first substrate film / second adhesive layer) / transparent resin film (TAC film) / first bonding layer (adhesive layer) / first diffusion inhibition layer / linear polarization layer (first orientation layer / first hardening layer) / second diffusion inhibition layer / second bonding layer (adhesive layer) / first phase retardation layer (second hardening layer / second orientation layer) / third bonding layer (adhesive layer) / second phase retardation layer (third hardening layer / third orientation layer) / first adhesive layer / release film.

[0170] 〔Comparative Example 1〕

[0170] The surface of the circular polarizer with the diffusion suppression layer obtained above, exposed by peeling off the COP film on the side of the second phase difference layer, is bonded to the surface exposed by peeling off one of the release films from the release film with the first adhesive layer obtained above, to obtain a laminate (a laminate of a transparent resin film, a circular polarizer, a first adhesive layer, and a release film). The surface of the laminate exposed by peeling off the release PET film on the side of the circular polarizer is bonded to the surface exposed by peeling off the release film from the surface protective film (2) with the release film obtained above, to obtain an optical laminate (5). The layer structure of the optical laminate (5) is a surface protective film (2) (first substrate film / second adhesive layer) / first diffusion inhibition layer / linear polarization layer (first orientation layer / first hardening layer) / second diffusion inhibition layer / second bonding layer (adhesive layer) / first phase difference layer (second hardening layer / second orientation layer) / third bonding layer (adhesive layer) / second phase difference layer (third hardening layer / third orientation layer) / first adhesive layer / release film.

[0171] 〔Comparative Example 2〕

[0171] Optical laminate (6) was obtained in the same manner as in Comparative Example 1, except that the surface protective film (1) with the separation film obtained above was used instead of the surface protective film (2) with the separation film. The layer structure of the optical laminate (6) is: surface protective film (1) (first substrate film / second adhesive layer) / first diffusion inhibition layer / linear polarization layer (first orientation layer / first hardening layer) / second diffusion inhibition layer / second bonding layer (adhesive layer) / first phase difference layer (second hardening layer / second orientation layer) / third bonding layer (adhesive layer) / second phase difference layer (third hardening layer / third orientation layer) / first adhesive layer / release film.

[0172] [Evaluation]

[0172] (Determination of the tensile modulus of elasticity of the first substrate film)

[0172] A rectangular test piece (1) with a length of 100 mm and a width of 25 mm was cut from the first substrate film used for surface protective films (1) and (2). Using the upper and lower clamps of a tensile testing machine [Shimadzu Corporation AUTOGRAPH AG-1S testing machine], the test piece (1) was clamped at both ends along its long side with the clamps spaced 5 cm apart. The test piece was stretched along its long side at a temperature of 23°C and a relative humidity of 55%. The tensile modulus of elasticity at 23°C was calculated in MPa from the slope of the initial straight line of the obtained stress-deformation curve. The results are shown in Table 1.

[0173] (Determination of tensile modulus of elasticity of transparent resin film)

[0173] Except for the transparent resin film used in the embodiments, the tensile modulus of the transparent resin film was calculated in the same order as the determination of the tensile modulus of the first substrate film described above. The results are shown in Table 1.

[0174] (Measurement of adhesion)

[0174] A test piece (2) with a width of 25 mm and a length of approximately 150 mm was cut from the optical laminates (1) to (6) obtained in the Examples and Comparative Examples. Using a tensile testing machine (Shimadzu Corporation AUTOGRAPH AG-1S testing machine), one end of the test piece (2) in the length direction was clamped, and a 90° peel test was performed at a crosshead speed (clamp movement speed) of 200 mm / min in an environment with a temperature of 23°C and a relative humidity of 60%, according to JIS K 6854-1:1999 "Adhesives - Peel adhesion strength test method - Part 1: 90° peel", to measure the peel force when peeling the surface protective film from the test piece (2) and the peel force when peeling the release film from the test piece (2). The peel force when peeling the surface protective film was taken as the adhesion force F1 between the surface protective film and the transparent resin film, and the peel force when peeling the release film was taken as the adhesion force F2 between the first adhesive layer and the release film. The results are shown in Table 1.

[0175] (Peeling test of the peeling film)

[0175] Test pieces (3) with a width of 80 mm and a length of approximately 50 mm were cut from the optical laminates (1) to (6) obtained in the Examples and Comparative Examples, respectively. The protective film side of the test piece (3) was bonded to Corning glass (0.4 mm thick) with an adhesive layer (pressure-sensitive adhesive, 5 μm thick) in between. After the Corning glass was bonded, a release tape (SERO TAPE (registered trademark) CT-24; manufactured by NICHIBAN Co., Ltd.) was applied to the release film of the test piece (3). The release tape was 24 mm wide and 80 mm long, and was extended across one side of the test piece (3). It was applied to the surface of the release film for a length of 30 mm from one end of the release tape in the length direction (see Figure 3). This tape was fixed to the evaluation table of a high-speed peel tester (manufactured by Imada Seisakusho Co., Ltd.).

[0176] Next, the end of the peeling tape opposite to the end on which the test piece (3) is mounted is held with the gripping part of a high-speed peel tester, and a 180° peel test is performed with the angle (peeling angle) relative to the surface direction of the test piece (3) set to 180° and the peeling speed set to 2.4 m / min. The results of the test are evaluated according to the following criteria.

[0176] A: The tensile force of the peeling film is less than 2N.

[0176] B: The tensile force of the peeling film exceeds 2N.

[0177] (Adhesion Test)

[0177] Test pieces (4) measuring 160 mm × 80 mm were cut from the optical laminates (1) to (6) obtained in the Examples and Comparative Examples, respectively. Using a high-precision laminator (HALTECH HAL650: manufactured by Sankyo), the release film was peeled off while the protective film side of the test piece (4) was adsorbed onto the suction cup side of the high-precision laminator, so that the exposed first adhesive layer was bonded to a 75 μm thick polyimide film (UPILEX-S 75S: manufactured by Ube Industries) disposed on the screen side of the high-precision laminator. The laminated laminate was removed, and the presence of any suction holes was checked. The results were evaluated according to the following criteria.

[0177] a: No trace of suction hole can be seen in the test piece (4).

[0177] b: Traces of suction holes can be seen on the test piece (4) or the surface protective film.

[0178] [Table 1]

Claims

1. An optical laminate, comprising, in sequence, a surface protective film, a transparent resin film, a circular polarizing plate, a first adhesive layer, and a release film, wherein a first diffusion suppression layer is further provided between the aforementioned transparent resin film and the aforementioned circular polarizing plate; wherein, The aforementioned surface protective film is peelable from the aforementioned transparent resin film; the aforementioned circular polarizer has a linear polarizing layer and a first phase reversal layer sequentially from the aforementioned transparent resin film side, the linear polarizing layer comprising a first hardened layer containing a first composition of a polymeric liquid crystal compound, and the first phase reversal layer comprising a second hardened layer containing a second composition of a polymeric liquid crystal compound; the aforementioned release film is peelable from the aforementioned first adhesive layer; the distance D from the surface of the aforementioned surface protective film on the side of the aforementioned transparent resin film to the surface of the aforementioned first adhesive layer on the side of the aforementioned circular polarizer is 20 μm or more and 55 μm or less; the thickness of the aforementioned transparent resin film is 5 μm or more and 40 μm or less; the tensile modulus of the aforementioned transparent resin film at a temperature of 23°C is 1500 MPa or more and 8000 MPa or less.

2. The optical laminate as described in claim 1, wherein, The aforementioned surface protective film has a second adhesive layer and a substrate film sequentially from the aforementioned transparent resin film side. The tensile modulus of the aforementioned substrate film at a temperature of 23°C is 2500MPa or more and 6000MPa or less, and the thickness of the aforementioned substrate film is 30μm or more and 120μm or less.

3. The optical laminate as described in claim 1 or 2 further comprises a first bonding layer between the aforementioned transparent resin film and the aforementioned circular polarizer.

4. The optical laminate as described in claim 1 or 2 further comprises a diffusion suppression layer between the aforementioned transparent resin film and the aforementioned circular polarizer.

5. The optical laminate as described in claim 4, wherein, The thickness of the aforementioned diffusion inhibition layer is less than 5 μm.

6. The optical laminate as described in claim 1 or 2, wherein, The aforementioned circular polarizer has a second bonding layer, which is bonded to the aforementioned linear polarizer and the aforementioned first phase difference layer.

7. The optical laminate as described in claim 1 or 2, wherein, The polymeric liquid crystal compound contained in the aforementioned first component is a polymeric liquid crystal compound that displays a lamellae liquid crystal phase, and the aforementioned first component further contains a pigment with anisotropic absorption.

8. The optical laminate as described in claim 1 or 2, wherein, The aforementioned second hardening layer is used to harden the aforementioned polymeric liquid crystal compound in a horizontal orientation relative to the surface of the aforementioned first retardation layer.

9. The optical laminate as described in claim 1 or 2, wherein, The aforementioned circular polarizer has a second phase retardation layer on the side opposite to the aforementioned linear polarizer layer, and the second phase retardation layer includes a third hardened layer containing a polymeric liquid crystal compound.

10. The optical laminate as described in claim 9, wherein, The aforementioned third hardening layer is hardened in a state where the aforementioned polymeric liquid crystal compound is oriented perpendicularly to the surface of the aforementioned second phase difference layer.

11. The optical laminate as described in claim 1 or 2, wherein, The adhesion force F1 between the aforementioned surface protective film and the aforementioned transparent resin film, and the adhesion force F2 between the aforementioned first adhesive layer and the aforementioned release film satisfy the following relationship (1): |F1-F2|≧0.02[N / 25mm] (1).

Images