Optical laminate and image display device using same

Abstract

The invention provides an optical laminate and an image display device using the same. The optical laminate includes a liquid crystal alignment cured layer, and can suppress specific display unevenness when applied to an image display device. An optical laminate according to an embodiment of the present invention has a polarizing plate including a polarizer, and a phase difference layer laminated on the polarizing plate with an adhesive layer interposed therebetween. The phase difference layer includes, in order from the polarizer side, a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer. The retardation layer has a circular polarization function or an elliptical polarization function as a whole, and has Re (450) lt. Re (550) lt; re (650). In an embodiment of the present invention, the adhesive layer satisfies the following relationship: (logG ') / Tgt 1.7 (where G' is the storage modulus (Pa) of the adhesive layer and T is the thickness ([mu] m) of the adhesive layer.

Description

Technical Field

[0001] The present invention relates to an optical laminate and an image display device using the optical laminate. Background Art

[0002] In recent years, image display devices typified by liquid crystal display devices and electroluminescent (EL) display devices (for example, organic EL display devices and inorganic EL display devices) have been rapidly spreading. In an image display device, in most cases, an optical laminate including a retardation film (for example, an antireflection film in which a polarizer and a retardation film are integrated) is used. In recent years, along with the increasing expectation for thinning of the image display device, there has also been an increasing expectation for thinning of the optical laminate. For the purpose of thinning the optical laminate, progress has been made in thinning the retardation layer (retardation film) that contributes greatly to the thickness. As a representative example of the thin retardation film, a film obtained by aligning a liquid crystal compound and fixing its alignment state (hereinafter referred to as a liquid crystal film) can be cited. Since the liquid crystal compound has an extremely large birefringence (Δn) compared with a resin, the liquid crystal film can reduce the thickness for obtaining a desired in-plane retardation much more than a stretched film of a resin film. However, in an image display device using an optical laminate including a liquid crystal film, display unevenness sometimes occurs depending on the visual recognition environment (specifically, a phenomenon in which a particularly conspicuous thin pink line is visually recognized in the absorption axis direction of the polarizer).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-222282 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The present invention has been made to solve the above-described conventional problems, and its main object is to provide an optical laminate including a liquid crystal alignment cured layer and capable of suppressing specific display unevenness when applied to an image display device.

[0008] Means for Solving the Problems

[0009] [1] The optical laminate according to an embodiment of the present invention has a polarizer including a polarizer and a retardation layer laminated on the polarizer via an adhesive layer; the retardation layer includes a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer in this order from the polarizer side; the retardation layer as a whole has a circular polarization function or an elliptical polarization function, and has a relationship of Re(450) < Re(550) < Re(650); the adhesive layer satisfies the following relationship:

[0010] (logG') / T>1.7

[0011] Here, G' is the storage elastic modulus (Pa) of the adhesive layer, and T is the thickness (μm) of the adhesive layer.

[0012] [2] In the above [1], the adhesive layer is composed of an active energy ray-curable adhesive.

[0013] [3] In the above [1], the adhesive layer is composed of a binder.

[0014] [4] In any one of the above [1] to [3], the thickness of the first liquid crystal alignment solidified layer is 1.7 μm or less.

[0015] [5] According to another aspect of the present invention, there is provided an image display device comprising the optical layered body according to [1] to [4] above.

[0016] Effects of the Invention

[0017] According to the embodiment of the present invention, it is possible to realize an optical laminated body which includes a liquid crystal alignment solidified layer and can suppress specific display unevenness when applied to an image display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic cross-sectional view of an optical layered body according to one embodiment of the present invention.

[0019] Explanation of symbols

[0020] 10 Polarizer

[0021] 11 Polarizer

[0022] 12. Protective layer

[0023] 13. Protective layer

[0024] 20 Phase difference layer

[0025] 21 1st liquid crystal alignment solidification layer

[0026] 22 2nd liquid crystal alignment solidification layer

[0027] 30 Adhesive layer

[0028] 100 Optical laminate DETAILED DESCRIPTION

[0029] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0030] (Definition of Terms and Symbols)

[0031] The definitions of terms and symbols in this specification are as follows.

[0032] (1) Refractive index (nx, ny, nz)

[0033] “nx” is the refractive index in the direction where the refractive index in the plane is maximum (ie, the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0034] (2) In-plane phase difference (Re)

[0035] "Re(λ)" is the in-plane phase difference of the film measured by light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference of the film measured by light of wavelength 550nm at 23°C. When the thickness of the film is set to d(nm), Re(λ) is calculated by the formula: Re = (nx-ny)×d.

[0036] (3) Retardation in the thickness direction (Rth)

[0037] "Rth(λ)" is the phase difference in the thickness direction of the film measured by light of wavelength λnm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction of the film measured by light of wavelength 550nm at 23°C. When the thickness of the film is set to d(nm), Rth(λ) is calculated by the formula: Rth = (nx-nz) × d.

[0038] (4) Nz coefficient

[0039] The Nz coefficient is obtained by Nz=Rth / Re.

[0040] (5) Angle

[0041] When an angle is mentioned in this specification, unless otherwise specified, the angle includes angles in both clockwise and counterclockwise directions.

[0042] A. Optical laminate

[0043] Figure 1 It is a schematic cross-sectional view of an optical laminate of one embodiment of the present invention. The optical laminate 100 shown in the figure has a polarizer 10 and a phase difference layer 20. The polarizer 10 and the phase difference layer 20 are stacked via an adhesive layer 30. The polarizer 10 typically includes a polarizer 11 and protective layers 12 and 13 arranged on both sides of the polarizer 11. Depending on the purpose, at least one of the protective layers 12 and 13 may also be omitted. Therefore, the polarizer may be a so-called double-protection polarizer, a so-called single-protection polarizer, or may be composed of a polarizer alone. In one embodiment, the polarizer may be a single-protection polarizer in which the protective layer 13 is omitted.

[0044] The retardation layer 20 includes a first liquid crystal alignment cured layer 21 and a second liquid crystal alignment cured layer 22 in this order from the polarizer 10 side. The first liquid crystal alignment cured layer 21 and the second liquid crystal alignment cured layer 22 are laminated via an arbitrarily suitable adhesive layer (not shown: hereinafter, sometimes referred to as an interlayer adhesive layer). By using a liquid crystal alignment cured layer as the retardation layer, it is possible to achieve a desired in-plane retardation with a thickness that is extremely thin compared to a stretched film of a resin film. As a result, significant thinning of the optical laminate can be achieved. The retardation layer 20 as a whole (as a laminate of the first liquid crystal alignment cured layer 21 and the second liquid crystal alignment cured layer 22) has a circular polarization function or an elliptical polarization function, and has the relationship of Re(450) < Re(550) < Re(650). In one embodiment, the Nz coefficient of the retardation layer as a whole can be, for example, 0.30 to 0.70. It should be noted that in this specification, the "liquid crystal alignment cured layer" refers to a layer in which liquid crystal compounds are aligned in a predetermined direction within the layer and the alignment state thereof is fixed. The "liquid crystal alignment cured layer" is a concept including an orientation hardened layer obtained by curing a liquid crystal monomer.

[0045] In an embodiment of the present invention, the adhesive layer 30 satisfies the following relationship:

[0046] (logG’) / T > 1.7

[0047] where G' is the storage elastic modulus of the adhesive layer (Pa) and T is the thickness of the adhesive layer (μm). It should be noted that the left side of the above formula is sometimes referred to as the "display unevenness parameter". The display unevenness parameter can be, for example, 2.0 or more, and can also be, for example, 2.5 or more, and can also be, for example, 3.5 or more, and can also be, for example, 4.0 or more, and can also be, for example, 4.5 or more, and can also be, for example, 5.5 or more, and can also be, for example, 6.0 or more, and can also be, for example, 7.0 or more, and can also be, for example, 8.0 or more, and can also be, for example, 9.0 or more. The display unevenness parameter can be, for example, 15.0 or less, and can also be, for example, 10.0 or less.

[0048] When the inventors studied the further thinning of the optical stack containing a liquid crystal orientation solidification layer as a phase difference layer, they found that the image display device using the optical stack containing a liquid crystal orientation solidification layer as a phase difference layer sometimes produces a new problem of specific display unevenness according to the visual recognition environment. Specifically, it was found that in the reflection under the 3-wavelength light source, a phenomenon (sometimes referred to as linear unevenness) in which pink particularly conspicuous thin lines along the absorption axis direction of the polarizer are visually recognized throughout the whole may be produced. Furthermore, the inventors conducted an in-depth study on the suppression of such linear unevenness, and found that: by suppressing the interference of the optical stack, the linear unevenness can be suppressed. In addition, the inventors found that: even in the case of curing shrinkage in the interlayer adhesive layer, if the adhesive layer 30 is suppressed to follow such shrinkage, the interference of the optical stack can also be suppressed, and the result is that the linear unevenness can be well suppressed, and the present invention is completed. That is, such an effect brought by the embodiment of the present invention is to solve the effect of the newly discovered problem when studying the further thinning of the optical stack containing a liquid crystal orientation solidification layer as a phase difference layer, and it is an unexpected excellent effect. It should be noted that the embodiments of the present invention can, of course, suppress display unevenness that has been known so far.

[0049] As long as the above formula is satisfied, the adhesive layer 30 can adopt any suitable composition. Specifically, the adhesive layer can be composed of an adhesive or an adhesive. That is, the adhesive layer can be an adhesive layer or an adhesive layer. As an adhesive, for example, water-based adhesives, solvent-based adhesives, emulsion-based adhesives, solvent-free adhesives, active energy ray (representatively electron beams, ultraviolet rays, visible light) curing adhesives, thermosetting adhesives, and hot melt adhesives can be listed. Preferably, it is an adhesive, a water-based adhesive or an active energy ray curing adhesive; more preferably, it is an adhesive, a water-based adhesive or a free radical curing active energy ray curing adhesive. Since the free radical curing active energy ray curing adhesive is solvent-free, it is preferred from the perspective of environmental considerations, and it has the advantage of being thinner. Since the adhesive has no curing shrinkage, it can ensure smoothness and alleviate the dimensional shrinkage of the polarizer in a high temperature environment, so it has the advantage of suppressing the unevenness of the phase difference layer. Water-based adhesives are preferred from the perspective of environmental considerations because they do not use organic solvents, and have the advantage of being thinner. It should be noted that as active energy ray-curable adhesives, for example, adhesives that can be cured under light (visible light) with a wavelength of 380nm to 440nm can be cited. For convenience, such adhesives are sometimes referred to as ultraviolet curing adhesives.

[0050] In the optical laminate, the total thickness from the first liquid crystal orientation solidification layer to the second liquid crystal orientation solidification layer is preferably less than 20 μm, more preferably 3 μm to 10 μm. According to an embodiment of the present invention, it is possible to solve the problem of newly discovered linear unevenness in an optical laminate comprising a very thin liquid crystal orientation solidification layer. It should be noted that if the total thickness from the first liquid crystal orientation solidification layer to the second liquid crystal orientation solidification layer is in the above-mentioned range, the total thickness from the polarizer to the second liquid crystal orientation solidification layer (the actual total thickness of the optical laminate excluding the thickness of the adhesive for bonding to the image display panel) is, for example, less than 100 μm, and can be, for example, 30 μm to 80 μm.

[0051] In actual use, the optical laminate has an adhesive layer (not shown) as the outermost layer on the second liquid crystal orientation solidified layer side (image display panel side), and is made to be attached to the image display panel. In this case, on the surface of the adhesive layer, a release liner is preferably temporarily attached until the optical laminate is used. By temporarily attaching a release liner, the adhesive layer can be protected and a roll of the optical laminate can be formed.

[0052] Hereinafter, the components of the optical layered body will be described in detail.

[0053] B. Polarizer

[0054] B-1. Polarizer

[0055] The polarizer 11 is typically formed of a polyvinyl alcohol (PVA) resin film containing a dichroic substance (eg, iodine). Examples of the PVA resin include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and partially saponified ethylene-vinyl acetate copolymer.

[0056] The PVA resin preferably includes an acetoacetyl-modified PVA resin. If such a structure is used, a polarizer having a desired mechanical strength can be obtained. When the PVA resin as a whole is set to 100 wt %, the amount of the acetoacetyl-modified PVA resin is preferably 5 wt % to 20 wt %, more preferably 8 wt % to 12 wt %. If the amount is such a range, a polarizer having a more excellent mechanical strength can be obtained.

[0057] The polarizer preferably contains iodide or sodium chloride (sometimes collectively referred to as halide). Examples of iodide include potassium iodide, sodium iodide, and lithium iodide. The content of halide in the polarizer is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, relative to 100 parts by weight of PVA-based resin. The halide can be added to the coating liquid that forms the PVA-based resin layer as a precursor of the polarizer in the manufacturing method described later, and finally introduced into the polarizer. By introducing the halide into the polarizer, the orientation of the PVA molecules in the polarizer can be improved, thereby realizing a polarizer with excellent optical properties (representatively, a high degree of polarization and a high monomer transmittance).

[0058] The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is preferably 41.0% to 46.0%, more preferably 42.0% to 45.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more. According to an embodiment of the present invention, even if the single transmittance is in the above-mentioned range, the polarization degree can be maintained within such a range.

[0059] The thickness of the polarizer is, for example, 12 μm or less, preferably 10 μm or less, more preferably 1 μm to 8 μm, and further preferably 3 μm to 7 μm. By combining such a thin polarizer with a liquid crystal orientation solidification layer, a significant thinning of the optical laminate can be achieved. In addition, if the thickness of the polarizer is within the above range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0060] The polarizer can be produced by any appropriate method. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0061] Specific examples of polarizers composed of a single-layer resin film include polarizers obtained by dyeing and stretching hydrophilic polymer films such as PVA films, partially formalized PVA films, and partially saponified films of ethylene-vinyl acetate copolymers with dichroic substances such as iodine or dichroic dyes, and polyene-based oriented films such as dehydrated PVA films and dehydrochlorinated polyvinyl chloride films, etc. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching the film is used from the perspective of excellent optical properties.

[0062] The dyeing using iodine is performed, for example, by immersing the PVA membrane in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching can be performed after the dyeing treatment, or it can be performed while dyeing. In addition, it can also be dyed after stretching. As needed, the PVA membrane is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA membrane in water for washing before dyeing, not only can the stains and anti-blocking agents on the surface of the PVA membrane be washed away, but also the PVA membrane can be swelled to prevent uneven dyeing.

[0063] As a specific example of a polarizer obtained using a laminate, a laminate using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate using a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be cited. The polarizer obtained using a laminate using a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be made, for example, by the following method: a PVA-based resin solution is applied to a resin substrate and dried to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; the laminate is stretched and dyed to make the PVA-based resin layer into a polarizer. In this embodiment, it is preferred to form a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of the resin substrate. Stretching typically includes immersing the laminate in a boric acid aqueous solution for stretching. Furthermore, stretching may further include stretching the laminate in the air at a high temperature (e.g., above 95°C) before stretching in a boric acid aqueous solution as required. In addition, in the present embodiment, it is preferred that the laminate is provided with a drying shrinkage treatment that shrinks by more than 2% in the width direction by heating while conveying in the length direction. Representatively, the manufacturing method of the present embodiment includes sequentially performing an air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate. By introducing auxiliary stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, and high optical properties can be achieved. In addition, by improving the orientation of PVA in advance, when immersed in water in the subsequent dyeing process and stretching process, problems such as reduction and dissolution of the orientation of PVA can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecules and the reduction of the orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thus, the optical properties of the polarizer obtained by the treatment process of immersing the laminate in a liquid such as a dyeing treatment and an underwater stretching treatment can be improved. Furthermore, by shrinking the laminate in the width direction using a drying shrinkage treatment, the optical properties can be improved. The obtained laminate of resin substrate / polarizer can be used directly (that is, the resin substrate can also be used as a protective layer of polarizer), or can be used on the peeling surface obtained by peeling off the resin substrate from the laminate of resin substrate / polarizer or on the surface on the opposite side of the peeling surface and any suitable protective layer corresponding to the purpose. The details of the manufacturing method of such a polarizer are recorded in, for example, Japanese Patent Publication No. 2012-73580 and Japanese Patent No. 6470455. The overall records of these publications are cited in this specification as a reference.

[0064] B-2. Protective layer

[0065] The protective layers 12 and 13 are composed of any suitable resin film. As the material constituting the resin film, representative examples include cellulose resins such as triacetyl cellulose (TAC), cycloolefin resins such as polynorbornene, (meth) acrylic resins, polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. As a representative example of (meth) acrylic resins, (meth) acrylic resins with lactone ring structures can be listed. (Meth) acrylic resins with lactone ring structures are, for example, recorded in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084. These publications are cited in this specification as reference. From the viewpoint of ease of processing into a special shape, cellulose resins are preferred, and TAC is more preferred. From the viewpoint of obtaining a polarizing plate having low water vapor permeability and excellent durability, cycloolefin resins and (meth)acrylic resins are preferred.

[0066] The optical laminate is typically configured on the visual recognition side of the image display device, and the protective layer 12 is typically configured on its visual recognition side. Therefore, for the protective layer 12, surface treatment can also be implemented as needed. As a surface treatment, for example, hard coating treatment, anti-reflection treatment, anti-adhesion treatment, and anti-glare treatment can be listed. And / or, for the protective layer 12, it is also possible to implement a treatment to improve the visual recognition of the situation of visual recognition through polarized sunglasses as needed (representatively, giving (elliptical) circular polarization function, giving ultra-high phase difference). By implementing such a treatment, even in the case of visually recognizing the display screen through polarized lenses such as polarized sunglasses, excellent visual recognition can be achieved. Therefore, the optical laminate is also suitably applicable to image display devices that can be used outdoors.

[0067] In one embodiment, the protective layer 13 is preferably optically isotropic. In this specification, “optically isotropic” means that the in-plane retardation Re(550) is 0 nm to 10 nm and the thickness direction retardation Rth(550) is -10 nm to +10 nm.

[0068] The thickness of each of the protective layers 12 and 13 is preferably 10 to 80 μm, more preferably 12 to 40 μm, and further preferably 15 to 35 μm. When the protective layer 12 is surface treated, the thickness of the protective layer 12 includes the thickness of the surface treated layer.

[0069] C. Phase difference layer

[0070] The retardation layer 20 includes the first liquid crystal alignment cured layer 21 and the second liquid crystal alignment cured layer 22 in this order from the polarizer side as described above. Further, as described above, the retardation layer 20 as a whole (as a laminate of the first liquid crystal alignment cured layer 21 and the second liquid crystal alignment cured layer 22) has a circular polarization function or an elliptical polarization function, and has a relationship of Re(450) < Re(550) < Re(650). Regarding the description of the retardation layer in this item, when it is simply referred to as "retardation layer", it means the description of the retardation layer as a whole, and when it is simply referred to as "liquid crystal alignment cured layer", it means the summary description of the first liquid crystal alignment cured layer and the second liquid crystal alignment cured layer.

[0071] The Re(550) of the retardation layer 20 is preferably 100 nm to 200 nm, more preferably 110 nm to 180 nm, still more preferably 120 nm to 170 nm, and particularly preferably 130 nm to 150 nm. If the Re(550) of the retardation layer is in such a range, the retardation layer combined with the polarizer can exhibit a good circular polarization function or elliptical polarization function.

[0072] The retardation layer 20 has a relationship of Re(450) < Re(550) < Re(650). That is, the retardation layer 20 preferably shows an inverse dispersion wavelength dependence in which the phase difference value increases corresponding to the wavelength of the measurement light. If it is such a configuration, a good antireflection function can be achieved in a very wide wavelength band. Re(450) / Re(550) is, for example, more than 0.5 and less than 1.0, preferably 0.7 to 0.95, more preferably 0.75 to 0.92, and still more preferably 0.8 to 0.9. Re(650) / Re(550) is preferably 1.0 or more and less than 1.15, more preferably 1.03 to 1.1.

[0073] In one embodiment, the Nz coefficient of the retardation layer 20 can be, for example, 0.30 to 0.70 as described above. Therefore, the retardation layer 20 shows a refractive index characteristic of nx > nz > ny. If it is such a configuration, reflection in the tilt direction can be well prevented, and a wide viewing angle of the antireflection function can be achieved. The Nz coefficient is preferably 0.35 to 0.65, more preferably 0.40 to 0.60, and still more preferably 0.45 to 0.55.

[0074] As the liquid crystal compound used in the liquid crystal orientation solidification layer, for example, liquid crystal polymers and liquid crystal monomers can be listed. The liquid crystal compound is preferably capable of polymerization (i.e., liquid crystal monomer). If the liquid crystal compound is capable of polymerization, then by orienting the liquid crystal compound and polymerizing it, the orientation state of the liquid crystal compound can be fixed. Here, the polymer formed by polymerization is non-liquid crystal. Therefore, the formed liquid crystal orientation solidification layer, for example, does not cause the transition to liquid crystal phase, glass phase, and crystalline phase caused by temperature changes that are unique to liquid crystal compounds. As a result, the liquid crystal orientation solidification layer becomes a phase difference layer with excellent stability that is not affected by temperature changes.

[0075] In one embodiment, the liquid crystal orientation solidification layer can be formed using a composition comprising a liquid crystal compound (polymerizable liquid crystal compound, i.e., liquid crystal monomer) that can be polymerized. The polymerizable liquid crystal compound contained in the composition in this specification refers to a compound having a polymerizable group and having liquid crystal properties. The polymerizable group refers to a group that participates in the polymerization reaction, preferably a photopolymerizable group. Wherein, the photopolymerizable group refers to a group that can participate in the polymerization reaction by an active free radical, acid, etc. generated by a photopolymerization initiator. As a liquid crystal monomer, for example, the polymerizable mesogen compounds recorded in Japanese Patent Table 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171 and GB2280445, etc., etc. can be used. Specific examples of such polymerizable mesogen compounds include LC242 manufactured by BASF, E7 manufactured by Merck, and LC-Sillicon-CC3767 manufactured by Wacker-Chem.

[0076] The liquid crystal compound may be thermotropic or lyotropic in its liquid crystal properties. In addition, the liquid crystal phase may be a nematic liquid crystal or a smectic liquid crystal. From the perspective of ease of manufacture, the liquid crystal properties are preferably thermotropic nematic liquid crystals.

[0077] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type thereof. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

[0078] The birefringence Δn of the liquid crystal orientation solidified layer is preferably 0.06 or more, more preferably 0.08 or more, further preferably 0.09 or more, and particularly preferably 0.10 or more. The upper limit of Δn can be, for example, 0.13, and can be, for example, 0.12. If Δn is such a range, the desired in-plane phase difference can be achieved with a very thin thickness. As a result, the liquid crystal orientation solidified layer and the optical laminate can be further thinned, which can ultimately contribute to the significant thinning of the image display device.

[0079] The liquid crystal orientation solidified layer can exhibit a reverse dispersion wavelength characteristic in which the phase difference value increases according to the wavelength of the measuring light, a positive wavelength dispersion characteristic in which the phase difference value decreases according to the wavelength of the measuring light, or a flat wavelength dispersion characteristic in which the phase difference value does not change substantially according to the wavelength of the measuring light.

[0080] The first liquid crystal orientation solidification layer 21 can function as a λ / 2 plate, and the second liquid crystal orientation solidification layer 22 can function as a λ / 4 plate. Specifically, the Re(550) of the first liquid crystal orientation solidification layer is preferably 150nm to 300nm, more preferably 200nm to 270nm, and further preferably 220nm to 260nm; the Re(550) of the second liquid crystal orientation solidification layer is preferably 100nm to 200nm, more preferably 110nm to 160nm, and further preferably 120nm to 140nm. The thickness of the first liquid crystal orientation solidification layer can be adjusted in a manner to obtain the desired in-plane phase difference of the λ / 2 plate. In one embodiment, the thickness of the first liquid crystal orientation solidification layer can be, for example, 2.0μm to 4.0μm. In other embodiments, the thickness of the first liquid crystal orientation solidification layer is preferably 1.7μm or less, more preferably 1.6μm or less, and further preferably 1.5μm or less. In this case, the thickness of the first liquid crystal orientation solidification layer can be, for example, 1.3μm or more. Like this, according to an embodiment of the present invention, the thickness of the first liquid crystal orientation solidification layer can be made thinner than before, while suppressing linear unevenness. The thickness of the second liquid crystal orientation solidification layer can be adjusted in a manner to obtain the desired in-plane phase difference of the λ / 4 plate. Specifically, its thickness can be, for example, 0.8μm to 2.5μm. The angle between the slow axis of the first liquid crystal orientation solidification layer and the transmission axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and further preferably 14° to 16°; the angle between the slow axis of the second liquid crystal orientation solidification layer and the transmission axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and further preferably 74° to 76°. It should be noted that the configuration order of the first liquid crystal orientation solidification layer and the second liquid crystal orientation solidification layer can also be reversed, and the angle between the slow axis of the first liquid crystal orientation solidification layer and the transmission axis of the polarizer and the angle between the slow axis of the second liquid crystal orientation solidification layer and the transmission axis of the polarizer can also be reversed.

[0081] The refractive index of the liquid crystal alignment cured layer may vary depending on the composition forming the liquid crystal alignment cured layer (substantially the type of liquid crystal compound, the type, number, combination, and amount of additives). LC1 The refractive index n of the second liquid crystal alignment cured layer is LC2 The refractive index n of the first liquid crystal alignment cured layer may be the same or different (the refractive index n of the first liquid crystal alignment cured layer may be LC1 The refractive index n of the second liquid crystal alignment cured layer may be larger. LC2 The refractive index n of the first liquid crystal alignment cured layer is LC1 The refractive index n of the second liquid crystal alignment solidified layer is preferably 1.55 to 1.75, and more preferably 1.60 to 1.70. LC2It is preferably 1.45 to 1.65, and more preferably 1.50 to 1.60. The refractive index n of the first liquid crystal alignment solidified layer LC1 The refractive index n of the second liquid crystal alignment cured layer is LC2 The refractive index n of the first liquid crystal alignment cured layer is LC1 The refractive index n of the second liquid crystal alignment cured layer is LC2 The absolute value of the difference can be, for example, 0.00 to 0.20. The refractive index of the liquid crystal orientation solidification layer is typically changed according to the composition of the liquid crystal orientation solidification layer in order to obtain the desired optical properties. As a result, linear unevenness may sometimes occur, but according to an embodiment of the present invention, by making the display unevenness parameter greater than 1.7, linear unevenness can be suppressed.

[0082] It is also possible to introduce a side chain type thermotropic liquid crystal polymer into the first liquid crystal orientation solidification layer and / or the second liquid crystal orientation solidification layer (essentially the liquid crystal composition forming them). By introducing a side chain type thermotropic liquid crystal polymer, the effect of vertically oriented liquid crystal monomers (homeotropic orientation) can be produced. As a result, the nz of the first liquid crystal orientation solidification layer and / or the second liquid crystal orientation solidification layer can be increased, and as a result, the Nz coefficient of the first liquid crystal orientation solidification layer and / or the second liquid crystal orientation solidification layer can be set to the above-mentioned desired range. Finally, the Nz coefficient of the phase difference layer can be set to the above-mentioned desired range without providing the positive C plate described later.

[0083] As the side chain type thermotropic liquid crystal polymer, a copolymer having a monomer unit containing a thermotropic liquid crystal segment side chain and a monomer unit containing a non-liquid crystal segment side chain is typically used. When the polymer has a thermotropic liquid crystal segment in the side chain, the side chain type liquid crystal polymer can be oriented when the liquid crystal composition is heated to a predetermined temperature. In addition, when the side chain type polymer has a non-liquid crystal segment in the side chain, the non-liquid crystal segment interacts with the photopolymerizable liquid crystal monomer, which can produce an effect of vertically aligning the photopolymerizable liquid crystal monomer.

[0084] As the side chain type thermotropic liquid crystal polymer, a copolymer having a liquid crystalline monomer unit represented by the general formula (I) and a non-liquid crystalline monomer unit represented by the general formula (II) is preferably used.

[0085] [Chemical formula 1]

[0086]

[0087] [Chemical formula 2]

[0088]

[0089] In formula (I), R 1is a hydrogen atom or a methyl group, R 2 is a cyano group, a fluoro group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and X 1 For -CO 2 - or -OCO-. a is an integer of 1 to 6, and b and c are 1 or 2, respectively, independently.

[0090] In formula (II), R 3 is a hydrogen atom or a methyl group, R 4 It is an alkyl group having 7 to 22 carbon atoms, a fluoroalkyl group having 1 to 22 carbon atoms, or a group represented by the following general formula (III).

[0091] [Chemical formula 3]

[0092]

[0093] In formula (III), R 5 is an alkyl group having 1 to 5 carbon atoms, and d is an integer of 1 to 6.

[0094] The ratio of the liquid crystal monomer unit to the non-liquid crystal monomer unit in the side chain type liquid crystal polymer can be appropriately set according to the purpose. The ratio (molar ratio) of the non-liquid crystal monomer to the total of the liquid crystal monomer unit and the non-liquid crystal monomer unit is preferably 0.05 to 0.8, more preferably 0.1 to 0.6, and further preferably 0.15 to 0.5. If it is such a structure, a liquid crystal orientation solidified layer showing a desired refractive index characteristic (Nz coefficient) can be obtained.

[0095] The ratio of the liquid crystal monomer to the side chain liquid crystal polymer in the liquid crystal composition can be appropriately set according to the purpose. When the content of the side chain liquid crystal polymer is high, there is a tendency for the Nz coefficient to become smaller; when the content of the liquid crystal monomer is high, there is a tendency for the Nz coefficient to become larger. The content of the liquid crystal monomer is preferably 1.2 to 20 times, more preferably 1.3 to 10 times, further preferably 1.4 to 9 times, and particularly preferably 1.5 to 8 times relative to the content of the side chain liquid crystal polymer. If it is such a structure, a liquid crystal orientation solidified layer showing the desired refractive index characteristics (Nz coefficient) can be obtained.

[0096] Details of the side chain type liquid crystal polymer and the method for forming a liquid crystal alignment solidified layer having an Nz coefficient of less than 1.0 are described in Japanese Patent No. 6769921. The description of this patent is incorporated herein by reference.

[0097] The phase difference layer 20 may further include a positive C plate. The refractive index characteristics of the positive C plate show the relationship of nz>nx=ny. The phase difference Rth(550) in the thickness direction of the positive C plate is preferably -20nm to -300nm, more preferably -30nm to -250nm, further preferably -40nm to -200nm, and particularly preferably -50nm to -150nm. Here, "nx=ny" not only includes the case where nx and ny are strictly equal, but also includes the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the positive C plate can be less than 10nm.

[0098] The positive C plate can be formed, for example, using a composition containing the above-mentioned side chain type liquid crystal polymer. As a specific example of the method for forming the positive C plate, there can be cited the method described in

[0020] to

[0028] of Japanese Patent Publication No. 2002-333642. In this case, the thickness of the positive C plate is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and further preferably 0.5 μm to 5 μm.

[0099] D. Adhesive layer

[0100] The adhesive layer 30 may have any appropriate structure as long as the above-mentioned desired display unevenness parameter is achieved. The adhesive layer 30 is preferably composed of a binder, a water-based adhesive, or an active energy ray-curable adhesive (particularly an ultraviolet-curable adhesive) as described above.

[0101] Active energy ray curing adhesives typically contain monofunctional components, multifunctional components (curing components) and photopolymerization initiators. Monofunctional components and multifunctional components are respectively representative free radical polymerizable compounds. As preferred monofunctional components, for example, higher alkyl esters of (meth) acrylic acid and modified bodies thereof can be cited. Specifically, isostearyl acrylate, lauryl acrylate, acryloyl morpholine, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone, etc. can be cited. By using such a monofunctional component with a large molecular weight per functional group, an adhesive with a small curing shrinkage can be obtained. As a result, an adhesive layer with a small uneven thickness can be obtained. As preferred multifunctional components, for example, monomers and / or oligomers having functional groups such as more than two (meth) acrylate groups and (meth) acrylamide groups can be cited. Specifically, polyethylene glycol diacrylate, trimethylolpropane triacrylate, and glycerol triacrylate can be cited. As specific examples of monofunctional components other than the above, tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, phenoxydiethylene glycol acrylate, cyclic trimethylolpropane formal acrylate, dioxanediol diacrylate, EO modified diglycerol tetraacrylate, γ-butyrolactone acrylate, N-methylpyrrolidone, hydroxyethyl acrylamide, N-hydroxymethyl acrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, 9-vinyl carbazole, 4-vinylphenyl boronic acid, fluorene acrylate. In one embodiment, the monofunctional component or the multifunctional component has a ring structure. Specifically, acryloyl morpholine, γ-butyrolactone acrylate, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone, N-methylpyrrolidone, 9-vinyl carbazole, fluorene acrylate can be listed. Compounds having a ring structure have a small free volume (high density), so by using such compounds, an adhesive with a small curing shrinkage can be obtained. As a result, an adhesive layer with a small uneven thickness can be obtained. Monofunctional components or multifunctional components can be used only one, or two or more can be used in combination.

[0102] The active energy ray-curable adhesive may further contain a cationic polymerizable compound as required. The cationic polymerizable compound may be monofunctional or polyfunctional. As monofunctional cationic polymerizable compounds, for example, p-tert-butylphenyl glycidyl ether and 3-ethyl-3-[(2-ethylhexyl)oxy]oxetane may be listed. As polyfunctional cationic polymerizable compounds, for example, 3-ethyl-3-{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane may be listed. As cationic polymerizable compounds, silane coupling agents may also be used. As silane coupling agents, for example, 3-glycidoxypropyltrimethoxysilane may be listed.

[0103] The active energy ray curing adhesive may further contain an acrylic oligomer as required. The molecular weight of the acrylic oligomer may be suitably set according to the purpose. By using an acrylic oligomer that does not further form a bond, an adhesive having a small curing shrinkage can be obtained. As a result, an adhesive layer having a small uneven thickness can be obtained.

[0104] The active energy ray-curable adhesive may further contain a photopolymerization initiator as necessary. Examples of the photopolymerization initiator include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, and diethylthioxanthone.

[0105] The active energy ray-curable adhesive may further contain a plasticizer (for example, an oligomer component), a crosslinking agent, a diluent, etc., depending on the purpose. In addition, commercial products may be used for the above-mentioned components.

[0106] The smaller the absolute value of the difference between the refractive index of the active energy ray-curable adhesive and the refractive index of the adjacent layer (particularly, the first liquid crystal alignment cured layer) is, the more preferably it is.

[0107] The details of the active energy ray-curable adhesive are described in, for example, Japanese Patent Application Laid-Open No. 2018-017996. The description of the publication is incorporated herein by reference.

[0108] The water-based adhesive typically includes a polyvinyl alcohol (PVA) resin. The adhesive layer can be typically formed by applying a PVA resin aqueous solution and drying it. The average degree of polymerization of the PVA resin contained in the aqueous solution is preferably about 100 to 5000, and more preferably 1000 to 4000. The average degree of saponification is preferably about 85 mol% to 100 mol%, and more preferably 90 mol% to 100 mol%. If the average degree of polymerization and the average degree of saponification are in such a range, an adhesive layer (substantially the first adhesive layer) having excellent adhesion to the polarizer can be formed.

[0109] The PVA resin preferably contains an acetoacetyl group. This is because an optical laminate having excellent adhesion to the polarizer and the protective layer and excellent durability can be obtained. The PVA resin containing an acetoacetyl group can be obtained, for example, by reacting the PVA resin with diketene by any method. The acetoacetyl modification degree of the PVA resin containing an acetoacetyl group is typically 0.1 mol% or more, preferably about 0.1 mol% to 40 mol%, more preferably 1 mol% to 20 mol%, and particularly preferably 2 mol% to 7 mol%. It should be noted that the acetoacetyl modification degree is a value measured by NMR.

[0110] The resin concentration in the PVA-based resin aqueous solution is preferably 0.1 wt% to 15 wt%, more preferably 0.5 wt% to 10 wt%. The viscosity of the aqueous solution is preferably 1 to 50 mPa·s. The pH of the aqueous solution is preferably 2 to 6, more preferably 2.5 to 5, more preferably 3 to 5, and particularly preferably 3.5 to 4.5. If the resin concentration and viscosity of the PVA-based resin aqueous solution are within such a range, an adhesive layer having a desired thickness can be formed in an embodiment of the present invention.

[0111] In one embodiment, the PVA resin aqueous solution (and, consequently, the adhesive layer) may contain a metal compound colloid. The metal compound colloid is a substance obtained by dispersing metal compound particles in a dispersion medium, and is electrostatically stabilized due to mutual repulsion of like charges of the particles, and has long-term stability.

[0112] The average particle size of the fine particles forming the metal compound colloid can be set to any appropriate value as long as it does not adversely affect the optical properties such as transparency and polarization properties. It is preferably 1 nm to 100 nm, and more preferably 1 nm to 50 nm, because the fine particles can be uniformly dispersed in the adhesive layer.

[0113] As the metal compound, any appropriate compound can be used. For example, metal oxides such as aluminum oxide, silicon dioxide, zirconium oxide, and titanium dioxide; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, and calcium phosphate; and minerals such as diatomaceous earth, talc, clay, and kaolin. It is preferred to use a metal compound colloid having a positive charge. As the metal compound, aluminum oxide, titanium dioxide, and the like can be listed, and aluminum oxide is particularly preferred.

[0114] When the adhesive layer is an adhesive layer, the storage elastic modulus of the adhesive constituting the adhesive layer at 25° C. is preferably 5.0×10 6 Pa~3.0×10 9 Pa, preferably 1.0×10 7 Pa~2.0×10 9 Pa, more preferably 1.5×10 7 Pa~1.5×10 9 Pa. If the storage elastic modulus of the adhesive is within such a range, a desired display unevenness parameter can be achieved.

[0115] When the adhesive layer is an adhesive layer, the thickness of the adhesive layer may vary according to the storage elastic modulus of the adhesive constituting the adhesive layer. The thickness of the adhesive layer may be, for example, 0.05 μm to 7.0 μm, 0.1 μm to 6.0 μm, 0.5 μm to 5.0 μm, or 1.0 μm to 3.0 μm.

[0116] As the specific example of adhesive, acrylic adhesive, rubber adhesive, silicone adhesive, polyester adhesive, urethane adhesive, epoxy adhesive and polyether adhesive can be listed. By adjusting the type, number, combination and proportion of the monomers forming the base polymer of the adhesive, as well as the amount of cross-linking agent, reaction temperature, reaction time, etc., it is possible to prepare an adhesive with the desired characteristics corresponding to the purpose. The base polymer of the adhesive can be used alone or in combination of two or more. From the viewpoints of transparency, processability and durability, acrylic adhesive (acrylic adhesive composition) is preferred. The acrylic adhesive composition representatively comprises (meth) acrylic polymer as the main component as the base polymer. (Meth) acrylic polymer contains (meth) alkyl acrylate as the main monomer component. It should be noted that (meth) acrylic acid refers to acrylic acid and / or methacrylic acid.

[0117] The alkyl (meth)acrylate may be contained in a proportion of preferably 50% by weight or more, more preferably 60% by weight or more, further preferably 70% by weight or more, particularly preferably 80% by weight or more, and particularly preferably 90% by weight or more in all monomer components forming the (meth)acrylic polymer.

[0118] As the alkyl (meth)acrylate, preferably, there can be mentioned an alkyl (meth)acrylate having a linear or branched alkyl group with 1 to 18 carbon atoms. The alkyl group has more preferably 2 to 10 carbon atoms, and further preferably 3 to 8 carbon atoms. As the alkyl (meth)acrylate, for example, there can be mentioned methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate. The alkyl (meth)acrylate can be used alone or in combination.

[0119] (Meth) acrylic polymers may also contain a comonomer copolymerizable with (meth) alkyl acrylate as a monomer component. Examples of comonomers include carboxyl-containing monomers and hydroxyl-containing monomers. Carboxyl-containing monomers are compounds that contain carboxyl groups in their structures and polymerizable unsaturated double bonds such as (meth) acryloyl and vinyl groups. Examples of carboxyl-containing monomers include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Acrylic acid is preferred. Hydroxyl-containing monomers are compounds that contain hydroxyl groups in their structures and polymerizable unsaturated double bonds such as (meth) acryloyl and vinyl groups. As the hydroxyl-containing monomer, for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate can be listed. 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferred. From the viewpoint of adjusting the properties of the adhesive layer, comonomers other than the above can also be used. As such comonomers, for example, monomers containing amino groups, monomers containing amide groups, multifunctional monomers, cyclopolymerizable monomers, monomers containing sulfonic acid groups, monomers containing phosphoric acid groups, (meth) acrylates with alicyclic hydrocarbon groups, (meth) acrylates with aromatic hydrocarbon groups, vinyl esters, aromatic vinyl compounds, olefins, dienes, and vinyl ethers can be listed. Comonomers can be used alone or in combination.

[0120] The adhesive composition may also contain a crosslinking agent. As the crosslinking agent, an organic crosslinking agent, a multifunctional metal chelating agent, etc. may be used. As the organic crosslinking agent, for example, isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents may be cited. A multifunctional metal chelating agent is a substance in which a polyvalent metal is covalently bonded or coordinately bonded to an organic compound.

[0121] The amount of the cross-linking agent to be added is, for example, 0.01 to 5 parts by weight relative to 100 parts by weight of the (meth)acryl-based polymer.

[0122] The adhesive composition may also contain a silane coupling agent. The silane coupling agent preferably contains a reactive functional group. The reactive functional group of the silane coupling agent containing a reactive functional group is typically a functional group other than an anhydride group. As functional groups other than anhydride groups, for example, epoxy groups, mercapto groups, amino groups, isocyanate groups, isocyanurate groups, vinyl groups, styryl groups, acetoacetyl groups, urea groups, thiourea groups, (meth) acrylic groups, heterocyclic groups and combinations thereof can be cited. The silane coupling agent containing a reactive functional group can be used alone or in combination.

[0123] The amount of the reactive functional group-containing silane coupling agent blended is usually 0.001 to 2 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

[0124] The adhesive composition may also contain additives. Specific examples of additives include powders such as colorants and pigments, dyes, surfactants, plasticizers, adhesiveness imparting agents, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, inhibitors, inorganic or organic fillers, metal powders, particles, and foils. In addition, a redox system with a reducing agent may be used within a controllable range. The type, number, combination, content, etc. of the additives may be appropriately set according to the purpose.

[0125] When the adhesive layer is a pressure-sensitive adhesive layer, the storage elastic modulus of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer at 25° C. is preferably 8.0×10 4 Pa~1.0×10 6 Pa, preferably 9.0×10 4 Pa~5.0×10 5 Pa, more preferably 1.0×10 5 Pa~2.0×10 5 Pa, particularly preferably 1.1×10 5 Pa~1.5×10 5 Pa. If the storage elastic modulus of the binder is within such a range, a desired display unevenness parameter can be achieved.

[0126] When the adhesive layer is an adhesive layer, the thickness of the adhesive layer may vary according to the storage elastic modulus of the adhesive constituting the adhesive layer. The thickness of the adhesive layer may be, for example, 0.7 μm to 5.0 μm, 0.8 μm to 3.0 μm, or 1.0 μm to 3.0 μm.

[0127] E. Interlayer bonding layer

[0128] E-1. Overview

[0129] As described above, the interlayer adhesive layer (not shown) is an adhesive layer for laminating the first liquid crystal alignment fixed layer 21 and the second liquid crystal alignment fixed layer 22. The interlayer adhesive layer may be composed of a binder or an adhesive.

[0130] In one embodiment, the refractive index n of the first liquid crystal alignment cured layer is LC1 , the refractive index n of the second liquid crystal alignment cured layer LC2 and the refractive index n of the interlayer adhesive layer AD , and the thickness of the interlayer adhesive layer T AD and uneven thickness TVAD The following formula (1) is satisfied. It should be noted that the "refractive index" of the liquid crystal alignment solidification layer in this specification refers to the refractive index in the transmission axis direction of the polarizer unless otherwise specified. Since the adhesive layer is substantially optically isotropic, the refractive index n AD It is also isotropic.

[0131] |{(n LC1 +n LC2 ) / 2-n AD}|×(TV AD / T AD )×1000≤3.0 (1)

[0132] The left side of formula (1) is preferably 2.5 or less, more preferably 2.0 or less, further preferably 1.8 or less, particularly preferably 1.2 or less, and particularly preferably 0.7 or less. The absolute value of the left side of formula (1) is preferably smaller, and may be 0.0, for example.

[0133] Regardless of whether the interlayer adhesive layer is an adhesive layer or a pressure-sensitive adhesive layer, the refractive index n of the interlayer adhesive layer is AD For example, the refractive index n of the interlayer adhesive layer may be 1.45 or more, or 1.50 or more, or 1.52 or more. AD It is preferably 1.54 or more, more preferably 1.55 or more, further preferably 1.57 or more, and particularly preferably 1.60 or more. AD For example, it may be 1.63 or less.

[0134] When the interlayer adhesive layer is an adhesive layer, the thickness T of the interlayer adhesive layer is AD For example, it is 3 μm or more, preferably 4 μm or more, more preferably 5 μm or more, further preferably 10 μm or more, and particularly preferably 15 μm or more. AD For example, it may be 30 μm or less. When the interlayer adhesive layer is an adhesive layer, the thickness T of the interlayer adhesive layer is AD It is preferably 0.5 μm to 2.0 μm, and more preferably 0.8 μm to 1.2 μm. The thickness unevenness TV of the interlayer adhesive layer AD It is preferably 0.20 μm or less, more preferably 0.18 μm or less, and still more preferably 0.16 μm or less. AD For example, it may be 0.03 μm or more.

[0135] Hereinafter, the adhesive and the pressure-sensitive adhesive constituting the interlayer adhesive layer will be described respectively.

[0136] E-2. Adhesive

[0137] As adhesive, as long as it satisfies the above-mentioned characteristics, any suitable composition can be adopted. As the specific example of adhesive, acrylic adhesive, rubber adhesive, silicone adhesive, polyester adhesive, urethane adhesive, epoxy adhesive and polyether adhesive can be listed. By adjusting the type, number, combination and proportion of the monomers of the base polymer forming the adhesive, as well as the amount of cross-linking agent, reaction temperature, reaction time, etc., it is possible to prepare an adhesive with the desired characteristics corresponding to the purpose. The base polymer of the adhesive can be used alone, or two or more can be used in combination. From the viewpoints such as transparency, processability and durability, acrylic adhesive (acrylic adhesive composition) is preferred. Acrylic adhesive composition representatively comprises (methyl) acrylic polymer as main component as base polymer. (methyl) acrylic polymer can be contained in the adhesive composition in the solid content of the adhesive composition, for example, with a ratio of more than 50 weight %, preferably more than 70 weight %, more preferably more than 90 weight %.

[0138] The (meth) acrylic polymer preferably comprises an aromatic ring-containing monomer (m1) as a monomer component. As monomer (m1), a compound containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule can be used. As monomer (m1), such a compound can be used alone or in combination of two or more. The aromatic ring and the ethylenically unsaturated group can be directly bonded or bonded via a connecting group.

[0139] As the ethylenically unsaturated group, for example, (meth)acryloyl, vinyl, and (meth)allyl can be cited. From the viewpoint of polymerization reactivity, (meth)acryloyl is preferred, and from the viewpoint of flexibility and adhesiveness, acryloyl is more preferred. From the viewpoint of suppressing the decrease in the flexibility of the adhesive, as the monomer (m1), a compound having 1 ethylenically unsaturated group contained in one molecule (i.e., a monofunctional monomer) is preferably used.

[0140] The number of aromatic rings contained in the molecule of the compound 1 used as the monomer (m1) may be 1 or more than 2. The upper limit of the number of aromatic rings contained in the monomer (m1) is not particularly limited, and may be, for example, 16 or less. In some embodiments, from the viewpoint of the ease of preparation of the (meth)acrylic polymer and the transparency of the adhesive, the number of aromatic rings may be, for example, 12 or less, preferably 8 or less, more preferably 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less.

[0141] The aromatic ring possessed by the compound used as the monomer (m1) may be, for example, a benzene ring (which may be a benzene ring constituting a part of a biphenyl structure or a fluorene structure), a condensed ring of a naphthalene ring, an indene ring, an azulene ring, an anthracene ring, a phenanthrene ring, or the like carbon ring; for example, a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a thiophene ring, or the like heterocyclic ring. The heteroatoms contained as ring-constituting atoms in the above heterocyclic ring may be, for example, one or more selected from the group consisting of nitrogen, sulfur, and oxygen. In several embodiments, the heteroatoms constituting the heterocyclic ring may be one or both of nitrogen and sulfur. For example, the monomer (m1) may also have a structure formed by condensation of one or more carbon rings and one or more heterocyclic rings, such as a dinaphthophene structure.

[0142] Examples of compounds that can be preferably used as monomer (m1) include aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds. Aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds can be used alone or in combination of two or more. One or more aromatic ring-containing (meth)acrylates and one or more aromatic ring-containing vinyl compounds can also be used in combination.

[0143] The content of the monomer (m1) in the monomer component constituting the (meth) acrylic polymer can be set, for example, in a manner that allows for achieving an adhesive layer that takes into account the desired refractive index and adhesive properties (e.g., peel strength, flexibility, etc.) and / or optical properties (e.g., total light transmittance, haze value, etc.). In several embodiments, the content of the monomer (m1) in the monomer component can be, for example, 30% by weight or more, preferably 50% by weight or more, 60% by weight or more, or 70% by weight or more. From the viewpoint of easily obtaining a higher refractive index, in several embodiments, the content of the monomer (m1) can be, for example, more than 70% by weight, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The upper limit of the content of the monomer (m1) in the monomer component is 100% by weight. From the viewpoint of balancing high refractive index and adhesive properties and / or optical properties, it is advantageous to set the content of the above-mentioned monomer (m1) to less than 100 weight %, for example, preferably about 99 weight % or less, more preferably 98 weight % or less, 97 weight % or less, or 96 weight % or less. In several embodiments, the content of monomer (m1) may be 93 weight % or less, 90 weight % or less, 80 weight % or less, or 75 weight % or less. In several embodiments in which adhesive properties and / or optical properties are given more importance, the content of monomer (m1) in the monomer component may be 70 weight % or less, 60 weight % or less, or 45 weight % or less.

[0144] In several embodiments, as monomer (m1), from the aspect of easily obtaining a high refractive index effect, a monomer having more than two aromatic rings (preferably a carbocyclic ring) in one molecule can be preferably used. As an example of a monomer having more than two aromatic rings in one molecule (hereinafter, also referred to as "a monomer containing multiple aromatic rings"), a monomer having a structure in which two or more non-condensed aromatic rings are bonded via a connecting group, a monomer having a structure in which two or more non-condensed aromatic rings are directly (i.e., not via other atoms) chemically bonded, a monomer having a condensed aromatic ring structure, a monomer having a fluorene structure, a monomer having a dinaphthophene structure, a monomer having a dibenzothiophene structure, etc. can be listed. A monomer containing multiple aromatic rings can be used alone, or two or more can be used in combination.

[0145] As at least a part of the monomer (m1), a high refractive index monomer can be preferably used. Here, the so-called "high refractive index monomer" refers to a monomer whose refractive index is, for example, about 1.510 or more, preferably about 1.530 or more, and more preferably about 1.550 or more. There is no particular limit to the upper limit of the refractive index of the high refractive index monomer, but from the perspective of the ease of preparation of the adhesive composition and the ease of taking into account the flexibility suitable as an adhesive, for example, it is 3.000 or less, or 2.500 or less, or 2.000 or less, or 1.900 or less, or 1.800 or less, or 1.700 or less. The high refractive index monomer can be used alone or in combination of two or more.

[0146] It should be noted that the refractive index of the monomer can be measured, for example, using an Abbe refractometer under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25° C. As the Abbe refractometer, a model "DR-M4" manufactured by ATAGO or an equivalent thereof can be used. When a nominal value of the refractive index at 25° C. is provided by a manufacturer, the nominal value can be adopted.

[0147] As the high refractive index monomer, a monomer having a corresponding refractive index among the compounds included in the concept of the aromatic ring-containing monomer (m1) (for example, the compounds and compound groups exemplified above) can be suitably used. Specific examples include m-phenoxybenzyl acrylate (refractive index: 1.566, Tg of homopolymer: -35°C), 1-naphthylmethyl acrylate (refractive index: 1.595, Tg of homopolymer: 31°C), ethoxylated o-phenylphenol acrylate (number of repetitions of oxyethylene units: 1, refractive index: 1.578), benzyl acrylate (refractive index (nD20): 1.519, Tg of homopolymer: 6°C), phenoxyethyl acrylate (refractive index (nD20): 1.517, Tg of homopolymer: 2°C), phenoxydiethylene glycol acrylate (refractive index: 1.5 10. Tg of homopolymer: -35°C), 6-acryloxymethyl dinaphthophene (6MDNTA, refractive index: 1.75), 6-methacryloxymethyl dinaphthophene (6MDNTMA, refractive index: 1.726), 5-acryloxyethyl dinaphthophene (5EDNTA, refractive index: 1.786), 6-acryloxyethyl dinaphthophene (6EDNTA, refractive index: 1.722), 6-vinyl dinaphthophene (6VDNT, refractive index: 1.802), 5-vinyl dinaphthophene (abbreviation: 5VDNT, refractive index: 1.793).

[0148] The content of the high refractive index monomer (i.e., an aromatic ring-containing monomer having a refractive index of about 1.510 or more, preferably about 1.530 or more, and more preferably about 1.550 or more) in the monomer (m1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, 35% by weight or more, or 40% by weight or more. In several embodiments, from the viewpoint of easily obtaining a higher refractive index, the content of the high refractive index monomer in the monomer (m1) may be, for example, 50% by weight or more, preferably 70% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. Substantially 100% by weight of the monomer (m1) may be a high refractive index monomer. In addition, in several embodiments, for example, from the viewpoint of balancing the high refractive index with the adhesive properties and / or optical properties, the content of the high refractive index monomer in the monomer (m1) may be less than 100 wt %, or less than 98 wt %, or less than 90 wt %, or less than 80 wt %, or less than 65 wt %. In several embodiments, considering the adhesive properties and / or optical properties, the content of the high refractive index monomer in the monomer (m1) may be less than 70 wt %, or less than 50 wt %, or less than 25 wt %, or less than 15 wt %, or less than 10 wt %. The embodiments of the present invention may be implemented even if the content of the high refractive index monomer in the monomer (m1) is less than 5 wt %. It is also possible not to use a high refractive index monomer.

[0149] The (meth)acrylic polymer may also contain a monomer (comonomer) copolymerizable with the aromatic ring-containing monomer (m1) as a monomer component. Examples of the comonomer include aliphatic alkyl (meth)acrylates, alicyclic alkyl (meth)acrylates, carboxyl-containing monomers, hydroxyl-containing monomers, and amide-containing monomers. The type, number, combination, and content of the comonomer in the monomer component may be appropriately set according to the purpose.

[0150] Acrylic adhesive (acrylic adhesive composition) may also contain a refractive index enhancer according to the purpose. The so-called refractive index enhancer in this specification refers to a material that can improve the refractive index of the adhesive layer by using it. As the refractive index enhancer, a material with a high refractive index compared to the refractive index of the adhesive layer containing the refractive index enhancer may be preferably used. In addition, as the refractive index enhancer, a material with a high refractive index compared to the base polymer (e.g., acrylic polymer) of the adhesive layer containing the refractive index enhancer may be preferably used. By appropriately using the refractive index enhancer, a higher refractive index and practical adhesive performance may be appropriately taken into account. In several embodiments, the refractive index enhancer is preferably an organic material. The organic material used as the refractive index enhancer may be a polymer or a non-polymer. In addition, it may have a polymerizable functional group or may not have a polymerizable functional group. The refractive index enhancer may be used alone or in combination of two or more.

[0151] The amount of the refractive index enhancer relative to 100 parts by weight of the base polymer (when using multiple refractive index enhancers, their total amount) can be appropriately set according to the purpose. From the viewpoint of the high refractive index of the adhesive, the amount of the refractive index enhancer relative to 100 parts by weight of the base polymer can be set to, for example, more than 1 part by weight, and it is advantageous to set it to more than 3 parts by weight, preferably more than 5 parts by weight, or more than 7 parts by weight, or more than 10 parts by weight, or more than 15 parts by weight, or more than 20 parts by weight. In addition, in several embodiments, the amount of the refractive index enhancer relative to 100 parts by weight of the base polymer can be set to, for example, less than 80 parts by weight, and from the viewpoint of balancing the high refractive index of the adhesive and the reduction and suppression of the adhesive properties and optical properties, it is advantageous to set it to less than 60 parts by weight, and it is preferably set to less than 45 parts by weight. In several embodiments that place more emphasis on adhesive properties and optical properties, the amount of the refractive index enhancer used relative to 100 parts by weight of the base polymer may be, for example, 30 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 3 parts by weight or less. The embodiments of the present invention may be implemented even if the amount of the refractive index enhancer used in the adhesive layer relative to 100 parts by weight of the base polymer is less than 1 part by weight, or the refractive index enhancer is not substantially used. Here, the so-called substantially not used means at least not intentionally used.

[0152] (Additives (H RO ))

[0153] In some embodiments, as the refractive index enhancer, an organic material having a higher refractive index than the base polymer may be preferably used. Hereinafter, such an organic material may be referred to as an "additive (HRO )". Here, "H RO " indicates an organic material with a high refractive index. Additives (H RO ) may be used alone or in combination of two or more.

[0154] As an additive (H RO ) can be selected from organic materials, such as organic compounds having an aromatic ring and organic compounds having a heterocyclic ring (which may be an aromatic ring or a non-aromatic heterocyclic ring). RO The aromatic ring possessed by the organic compound having an aromatic ring used in the monomer (m1) (hereinafter also referred to as "aromatic ring-containing compound") can be selected from the same aromatic rings as the aromatic ring possessed by the compound used as the monomer (m1).

[0155] As an additive (H RO ) include aromatic ring-containing monomers such as benzyl acrylate, m-phenoxybenzyl acrylate, 2-(o-phenylphenoxy)ethyl acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, the above-mentioned monomers having a fluorene structure, monomers having a dinaphthophene structure, monomers having a dibenzothiophene structure, etc.; aromatic ring-containing compounds without ethylenically unsaturated groups such as 3-phenoxybenzyl alcohol, dinaphthophene and its derivatives (for example, compounds having a structure in which one or more substituents selected from hydroxyl, methanol, diethanol, glycidyl, etc. are bonded to the dinaphthophene ring).

[0156] The acrylic adhesive composition may preferably contain a silane coupling agent and / or a crosslinking agent. As the silane coupling agent, for example, epoxy-containing silane coupling agents may be cited. As the crosslinking agent, for example, isocyanate crosslinking agents and peroxide crosslinking agents may be cited. Furthermore, the acrylic adhesive composition may also contain additives. As specific examples of additives, antioxidants, conductive agents, colorants, pigments and other powders, dyes, surfactants, plasticizers, adhesion imparting agents, surface lubricants, leveling agents, softeners, anti-aging agents, light stabilizers, ultraviolet absorbers, inhibitors, inorganic or organic fillers, metal powders, particles, foils may be cited. In addition, a redox system with a reducing agent may also be used within a controllable range. The type, number, combination, content, etc. of the silane coupling agent, crosslinking agent and / or additive may be appropriately set according to the purpose.

[0157] E-3. Adhesive

[0158] The adhesive (adhesive composition) may typically contain (meth)acrylates containing an aromatic ring skeleton and metal oxide particles. Each of these is briefly described below. It should be noted that other components (such as curing components and adhesives) that may be included in the adhesive may be formed using known structures, so specific descriptions are omitted.

[0159] By containing (meth) acrylate with aromatic ring skeleton in the adhesive composition, an adhesive layer with a desired refractive index can be formed in an embodiment of the present invention. As the (meth) acrylate with aromatic ring skeleton, it is preferred to use at least one (meth) acrylate containing a group consisting of (meth) acrylate with polycyclic aromatic ring skeleton and (meth) acrylate with more than 2 aromatic rings. As such (meth) acrylate, for example, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 1-naphthyl (meth) acrylate, phenoxybenzyl (meth) acrylate, ethylene oxide modified o-phenylphenol (meth) acrylate, 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene and (meth) acrylic acid reactants. Among them, phenoxybenzyl (meth) acrylate and phenoxyethyl (meth) acrylate are more preferably used, and phenoxybenzyl (meth) acrylate is particularly preferably used. When the total amount of the adhesive composition is 100% by mass, the amount of the (meth)acrylate having an aromatic ring skeleton is preferably 20% by mass to 90% by mass, and more preferably 30% by mass to 80% by mass.

[0160] As metal oxide particles, for example, silicon oxide, zirconium oxide, titanium oxide, zinc oxide, antimony pentoxide, tin oxide, aluminum oxide, indium oxide, indium tin oxide, iron oxide, cerium oxide, yttrium oxide, manganese oxide, holmium oxide, copper oxide, bismuth oxide, cobalt oxide, cobalt tetraoxide, iron tetraoxide, magnesium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, scandium oxide, tantalum pentoxide, niobium pentoxide, iridium oxide, rhodium oxide, ruthenium oxide and composite oxides formed by combining them can be listed. Among them, zirconium oxide and titanium oxide are preferred, and zirconium oxide is particularly preferred. It should be noted that the metal oxide particles can be composed only of the metal oxides listed above, or can also contain other components, but it is preferred that the metal oxide accounts for the largest weight as a component in the particles. The metal oxide particles may be in any shape such as spherical, ellipsoidal, cubic, rectangular or pyramidal. It should be noted that the metal oxide particles may be those surface-treated by any appropriate method.

[0161] From the viewpoint of improving the stability of the metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer, the average particle size of the metal oxide particles is preferably 1 nm to 150 nm, and more preferably 1 nm to 50 nm. The average particle size of the metal oxide particles can be derived, for example, by the following method: by magnifying and observing the particles using a transmission electron microscope (TEM), a field emission transmission electron microscope (FE-TEM), a field emission scanning electron microscope (FE-SEM), etc., randomly selecting, for example, 1000 particles, measuring their maximum length, and calculating the arithmetic average thereof.

[0162] From the viewpoint of improving the stability of the metal oxide particles in the adhesive composition and improving the refractive index of the adhesive layer, the amount of the metal oxide particles is preferably 10% to 50% by mass, more preferably 15% to 40% by mass, when the total amount of the adhesive composition is set to 100% by mass.

[0163] The adhesive composition may further contain a hydroxyl-containing (meth) acrylate. If such a composition is used, the adhesive strength of the adhesive layer can be further improved. When the total amount of the adhesive composition is set to 100% by mass, the amount of the hydroxyl-containing (meth) acrylate is preferably 1% to 30% by mass, more preferably 3% to 20% by mass.

[0164] F. Image display device

[0165] The optical laminate described in the above items A to E can be applied to image display devices. Therefore, the embodiments of the present invention also include image display devices using such optical laminates. As representative examples of image display devices, liquid crystal display devices and organic EL display devices can be listed. The image display device of the embodiment of the present invention typically has the optical laminate described in the above items A to E on its visual recognition side.

[0166] Example

[0167] The present invention is specifically described below by way of examples, but the present invention is not limited to these examples. The measuring methods and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0168] (1) Storage elastic modulus

[0169] (1-1) Active Energy Ray Curable Adhesives and Water-Based Adhesives

[0170] The active energy ray-curable adhesive used in the examples and comparative examples was coated on a cycloolefin polymer film (COP film: manufactured by ZEON CORPORATION, product name "ZF14") (thickness 100 μm), and the same COP film was attached to the coated surface to obtain a laminate. The laminate was irradiated with an active energy ray irradiation device ("LightHAMMER10 Mark III" manufactured by Heraeus, valve: V valve) at a peak illuminance of 1600 mW / cm 2 , cumulative exposure 1000 / mJ / cm 2 (wavelength 380 nm to 440 nm) to obtain a cured product layer (monomer film) of an active energy ray-curable adhesive. The illuminance of the active energy ray was measured using "Sola-Check System" manufactured by Solatell.

[0171] The storage elastic modulus at 25° C. of the cured product layer (monomer film) of the obtained active energy ray-curable adhesive was measured under the following conditions using a dynamic viscoelasticity measuring apparatus (manufactured by TA Instruments, trade name “RSA-G2”).

[0172] (Load mode): Stretch

[0173] (Heating rate): 5℃ / min

[0174] (Frequency): 1Hz

[0175] (Initial strain): 0.1%

[0176] The water-based adhesive was also measured in the same manner as above.

[0177] (1-2) Adhesive

[0178] The solution of the acrylic adhesive composition used in the examples and comparative examples was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (Mitsubishi Chemical polyester film, thickness: 38 μm), and dried at 150°C for 3 minutes to prepare an adhesive sheet (thickness 1 mm). The adhesive sheet was punched into a disk shape with a diameter of 8 mm as a measurement sample. Using the measurement sample, the storage elastic modulus of the adhesive at 25°C was measured using a dynamic viscoelasticity measuring device (TA Instruments, trade name "ARES-G2") under the following conditions.

[0179] (Load mode): Torsion

[0180] (Heating rate): 5℃ / min

[0181] (Frequency): 1Hz

[0182] (Measurement temperature): -70℃~150℃

[0183] (2) Thickness

[0184] The measurement was performed using an interferometer film thickness meter ("MCPD9800" manufactured by Otsuka Electronics Co., Ltd.).

[0185] (3) Linear unevenness

[0186] A conventional acrylic adhesive was placed on the second liquid crystal orientation cured layer side of the optical laminate obtained in the examples and comparative examples, and the optical laminate was bonded to a V3 reflector (manufactured by NEODIS) via the acrylic adhesive to form a test sample. The obtained test sample was visually observed under a 3-wavelength fluorescent lamp and evaluated according to the following criteria.

[0187] 1: No linear unevenness was found

[0188] 2: Slight linear unevenness was observed

[0189] 3: Linear unevenness is observed, but it is tolerable in practical use.

[0190] 4: Linear unevenness is observed to a degree that is not acceptable in practical use.

[0191] 5: Significant linear unevenness

[0192] [Manufacturing Example 1: Preparation of Adhesive]

[0193] In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler, 94.9 parts of butyl acrylate, 0.1 parts of 2-hydroxyethyl acrylate, 5 parts of acrylic acid, and 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator were added together with 100 parts of ethyl acetate, and nitrogen was introduced while slowly stirring to replace the nitrogen. Then, the liquid temperature in the flask was maintained at about 55°C and a polymerization reaction was performed for 8 hours to prepare an acrylic polymer solution. With respect to 100 parts of the solid content of the obtained acrylic polymer solution, 0.6 parts of an isocyanate crosslinking agent (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd., an adduct of trimethylolpropane tolylene diisocyanate), 0.2 parts of benzoyl peroxide (NYPER BMT manufactured by NOF Corporation), and 0.2 parts of γ-glycidoxypropylmethoxysilane (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) were added to prepare a solution of an acrylic adhesive composition. The solution of the acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (release film: Mitsubishi Chemical Polyester Film (Co., Ltd.), MRF38) treated with a silicone release agent, and dried at 150°C for 3 minutes to form an adhesive layer of a predetermined thickness on the surface of the release film. The storage elastic modulus of the adhesive was 1.1×10 5 (Pa).

[0194] [Manufacturing Example 2: Preparation of Adhesive A]

[0195] 10 parts of hydroxyethyl acrylamide (trade name "HEAA", manufactured by KJ Chemicals), 50 parts of phenoxy diethylene glycol acrylate (trade name "LIGHT ACRYLATE P2H-A", manufactured by Kyoeisha Chemical Co., Ltd.), 25 parts of 1,9-nonanediol diacrylate (trade name "LIGHT ACRYLATE 1,9NDA", manufactured by Kyoeisha Chemical Co., Ltd.), 10 parts of acrylic oligomer (trade name "ARUFON UP-1190", manufactured by Toagosei Co., Ltd.), 3 parts of photopolymerization initiator (trade name "Omnirad 907", manufactured by IGM Resins BV) and 2 parts of photopolymerization accelerator (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) were stirred at 50°C for 1 hour to prepare adhesive A (active energy ray curing adhesive). The storage elastic modulus of adhesive A was 1.8×10 7 (Pa).

[0196] [Manufacturing Example 3: Preparation of Adhesive B]

[0197] 11 parts of hydroxyethyl acrylamide (trade name "HEAA", manufactured by KJ Chemicals), 1 part of acryloylmorpholine (trade name "ACMO", manufactured by KJ Chemicals), 4 parts of 2-acetoacetoxyethyl methacrylate (trade name "AAEM", manufactured by Mitsubishi Chemical Co., Ltd.), 59 parts of tripropylene glycol diacrylate (trade name "ARONIX M-220", manufactured by Toagosei Co., Ltd.), 1 part of 4-vinylphenylboric acid (manufactured by FUJIFILM Wako Pure Chemical Corporation), 10 parts of acrylic oligomer (trade name "ARUFONUP-1190", manufactured by Toagosei Co., Ltd.), 3 parts of photopolymerization initiator (trade name "Omnirad 907", manufactured by IGM Resins BV), and 1 part of photopolymerization accelerator (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd.) were stirred at 50° C. for 1 hour to prepare Adhesive B (active energy ray-curable adhesive). The storage elastic modulus of adhesive B is 1.3×10 9 (Pa).

[0198] [Manufacturing Example 4: Preparation of Adhesive C]

[0199] Adhesive C (aqueous adhesive) was prepared by mixing 6.02 parts of acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more, solid content concentration 4%, manufactured by Mitsubishi Chemical Co., Ltd., trade name "GOHSENX Z-200"), 25 parts of an aqueous solution containing positively charged alumina colloid (average particle size 15 nm) at a solid content concentration of 3.2%, and 18.98 parts of pure water. The storage elastic modulus of adhesive C was 1.5×10 9 (Pa).

[0200] [Example 1]

[0201] 1. Preparation of polarizer

[0202] 1-1. Preparation of polarizer

[0203] As the thermoplastic resin substrate, a long amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) having a Tg of about 75° C. was used, and one surface of the resin substrate was subjected to a corona treatment.

[0204] To 100 parts by weight of a PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1, 13 parts by weight of potassium iodide were added, and the resulting substance was dissolved in water to prepare a PVA aqueous solution (coating solution).

[0205] The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.

[0206] The obtained laminate was uniaxially stretched to 2.4 times in the longitudinal direction (length direction) in an oven at 130° C. (in-air auxiliary stretching treatment).

[0207] Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution prepared by mixing 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilization treatment).

[0208] Next, the film was immersed in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 per 100 parts by weight of water) at a liquid temperature of 30° C. for 60 seconds while adjusting the concentration so that the single body transmittance (Ts) of the polarizer finally obtained becomes a desired value (dyeing treatment).

[0209] Next, the sample was immersed in a crosslinking bath (boric acid aqueous solution prepared by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment).

[0210] Afterwards, the laminate was immersed in an aqueous boric acid solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C, and was uniaxially stretched (underwater stretching treatment) in the longitudinal direction (length direction) between rollers with different peripheral speeds so that the total stretching ratio became 5.5 times.

[0211] Thereafter, the laminate was immersed in a washing bath (an aqueous solution prepared by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment).

[0212] Thereafter, the sheet was brought into contact with a SUS heating roll whose surface temperature was maintained at about 75° C. while being dried in an oven maintained at about 90° C. (drying shrinkage treatment).

[0213] In this manner, a polarizer having a thickness of about 5 μm was formed on the resin substrate, thereby obtaining a polarizing plate having a structure of resin substrate / polarizer. The single-body transmittance Ts of the polarizer was 43.3%.

[0214] 1-2. Preparation of polarizing film

[0215] On the surface of the obtained polarizer (the surface opposite to the resin substrate), the HC-COP film is attached via an ultraviolet curing adhesive. It should be noted that the HC-COP film is a film having an HC layer (thickness 4 μm) formed on a cycloolefin resin (COP) film (thickness 25 μm), and is attached in such a way that the COP film becomes the polarizer side. It should be noted that the Re (550) of the COP film is 135 nm. Next, the resin substrate is peeled off to obtain a polarizing plate having a structure of HC layer / COP film (protective layer) / polarizer.

[0216] 2. Fabrication of phase difference layer

[0217] A photopolymerizable liquid crystal compound ("Paliocolor LC242" manufactured by BASF, the following chemical formula) showing a nematic liquid crystal phase was dissolved in cyclopentanone to prepare a solution having a solid content concentration of 30% by weight. A surfactant ("BYK-360" manufactured by BYK-Chemie) and a photopolymerization initiator ("Omnirad907" manufactured by IGM Resins) were added to the solution to prepare a liquid crystal composition solution. The amount of surfactant and polymerization initiator added was set to 0.01 parts by weight and 3 parts by weight, respectively, relative to 100 parts by weight of the photopolymerizable liquid crystal compound. As a substrate, a biaxially stretched norbornene film ("ZeonorFilm" manufactured by ZEON CORPORATION, thickness 33μm, Re(550) = 135nm) was prepared. The above-mentioned liquid crystal composition was applied to the substrate using a rod coater in such a manner that Re(550) became 240nm, and the liquid crystal was oriented by heating at 100°C for 3 minutes. After cooling to room temperature, the samples were irradiated in a nitrogen atmosphere with a cumulative light intensity of 400 mJ / cm 2 The substrate was photocured by ultraviolet light to obtain a laminate having a structure of a substrate / a first liquid crystal orientation solidification layer. The first liquid crystal orientation solidification layer was oriented along the surface and had a thickness of 1.7 μm. The same operation as above was performed except that the coating thickness was changed to obtain a laminate having a substrate / a second liquid crystal orientation solidification layer (oriented along the surface, thickness 0.92 μm, Re (550) = 130 nm).

[0218] [Chemical formula 4]

[0219]

[0220] 3. Fabrication of optical laminates

[0221] After the first liquid crystal orientation solidification layer is bonded to the surface of the polarizer of the polarizer via the adhesive (thickness 1 μm) of Manufacturing Example 1, the substrate is peeled off. Next, the second liquid crystal orientation solidification layer is bonded to the surface of the first liquid crystal orientation solidification layer via an acrylic adhesive (5 μm), and the substrate is peeled off to obtain an optical laminate having a structure of polarizer / adhesive layer / first liquid crystal orientation solidification layer / interlayer adhesive layer / second liquid crystal orientation solidification layer. In the optical laminate, the angle formed by the transmission axis of the polarizer of the polarizer and the slow axis of the first liquid crystal orientation solidification layer is 15°, and the angle formed by the transmission axis of the polarizer of the polarizer and the slow axis of the second liquid crystal orientation solidification layer is 75°. The obtained optical laminate is provided for the above-mentioned "linear unevenness" evaluation. The results are shown in Table 1.

[0222] [Examples 2 to 7 and Comparative Examples 1 to 4]

[0223] An optical layered body was obtained in the same manner as in Example 1 except that the configuration of the adhesive layer was changed as shown in Table 1. The obtained optical layered body was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0224] Table 1

[0225]

[0226] [evaluate]

[0227] As shown in Table 1, linear unevenness can be suppressed by controlling the display unevenness parameter.

[0228] Industrial Applicability

[0229] The optical layered body according to the embodiment of the present invention can be suitably used in an image display device (typically, a liquid crystal display device and an organic EL display device).

Claims

1. An optical laminate having a polarizing plate including a polarizer and a retardation layer laminated on the polarizing plate via an adhesive layer, wherein the retardation layer includes a first liquid crystal alignment cured layer and a second liquid crystal alignment cured layer in this order from the polarizing plate side, the retardation layer as a whole has a circular polarization function or an elliptical polarization function, and has a relationship of Re(450) < Re(550) < Re(650), the adhesive layer satisfies the following relationship: (logG’) / T > 1.7 in, where G’ is the storage elastic modulus of the adhesive layer, with the unit of Pa, and T is the thickness of the adhesive layer, with the unit of μm.

2. The optical layered body according to claim 1, wherein: The adhesive layer is composed of an active energy ray curable adhesive.

3. The optical layered body according to claim 1, wherein: The adhesive layer is composed of an adhesive.

4. The optical layered body according to any one of claims 1 to 3, wherein The thickness of the first liquid crystal alignment cured layer is 1.7 μm or less.

5. An image display device including the optical laminate according to any one of claims 1 to 3.

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