Optical laminate and elliptical polarizing plate comprising the same

Abstract

The purpose of this invention is to provide an optical laminate that exhibits low strain during bending, high flexibility, and excellent oblique reflectivity, particularly suitable for flexible displays. The optical laminate comprises, in sequence, a retardation film, a polarizer, and a transparent protective film, wherein the aforementioned retardation film contains a polarizer having a polarization density of 100 g / m². 2 A substrate film with a permeability of more than 24 hours and a liquid crystal curing film formed on the substrate film, wherein the thickness of the liquid crystal curing film is more than 0.5 μm and less than 3 μm, and satisfies the following formulas (1) and (2) in a single layer, wherein the aforementioned polarizer is composed of a polyvinyl alcohol resin film containing a dichroic pigment, the aforementioned transparent protective film has a total light transmittance of more than 90% and a 380 nm transmittance of less than 30%, and the aforementioned phase difference film, the aforementioned polarizer and the aforementioned transparent protective film are adjacent to each other through an adhesive layer. Re(450) / Re(550)≤1.00(1) 1.00≤Re(650) / Re(550)(2) [where Re(λ) represents the in-plane phase difference value at wavelength λ].

Description

Technical Field

[0001] The present invention relates to an optical laminate, a roll of the aforementioned optical laminate, and an elliptical polarizing plate comprising the aforementioned optical laminate and an organic EL display device. Background Technology

[0002] An elliptical polarizing plate is an optical component formed by stacking a polarizing plate and a retardation plate. For example, in devices that display images in a planar state, such as organic EL image display devices, it is used to prevent light reflection at the electrodes constituting the device. As the retardation plate constituting the elliptical polarizing plate, a so-called λ / 4 plate is usually used. As such a retardation plate, a retardation plate using a liquid crystal cured film made by coating a polymerizable liquid crystal compound onto a substrate and then curing it is known (Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-207765 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In recent years, there has been a demand for flexible displays, requiring thin and highly flexible elliptical polarizing plates. The retardation film obtained by curing a polymeric liquid crystal compound, as described in reference 1, is suitable for flexible displays from the perspective of achieving thinness. Elliptical polarizing plates (films) can be fabricated by transferring a retardation plate (film) formed from such a liquid crystal cured film onto a polarizing plate via a pressure-sensitive adhesive.

[0008] However, the inventors of this application have discovered that if a pressure-sensitive adhesive is used to transfer the phase retardation plate formed by the liquid crystal curing film, strain is easily generated at the bending point when the elliptical polarizing plate formed therefrom is bent, which will result in striped defects and an increase in light reflectivity from the tilt direction (oblique reflectivity).

[0009] The purpose of this invention is to provide an optical laminate that is not prone to strain when bent, has high flexibility and excellent oblique reflectivity, and is particularly suitable for flexible displays.

[0010] Methods for solving problems

[0011] The inventors of this application conducted in-depth research to solve the aforementioned problems, and as a result, completed this invention. That is, this invention includes the following aspects.

[0012] [1] An optical laminate, which is an optical laminate comprising a phase retardation film, a polarizer and a transparent protective film in sequence.

[0013] The aforementioned phase retardation film contains 100 g / m 2 A substrate film with a moisture permeability of 24 hours or more, and a liquid crystal curing film formed on the substrate film, wherein the thickness of the liquid crystal curing film is 0.5 μm or more and 3 μm or less, and satisfies the following formulas (1) and (2) in a single layer:

[0014] Re(450) / Re(550)≤1.00 (1)

[0015] 1.00≤Re(650) / Re(550) (2)

[0016] [In the formula, Re(λ) represents the in-plane phase difference at wavelength λ]

[0017] The aforementioned polarizer is composed of a polyvinyl alcohol-based resin film containing dichroic pigments. The aforementioned transparent protective film has a total light transmittance of over 90% and a 380nm transmittance of less than 30%.

[0018] The aforementioned phase retardation film, the aforementioned polarizer, and the aforementioned transparent protective film are adjacent to each other, separated by an adhesive layer.

[0019] [2] As described in [1] above, the optical laminate has a total light transmittance of 90% or more and an absolute value of the phase difference Rth(550) in the thickness direction for 550nm light of 5nm or less.

[0020] [3] As described in [1] or [2] above, the aforementioned phase difference film has an optical alignment film with a thickness of more than 10 nm and less than 1000 nm between the substrate film and the liquid crystal curing film.

[0021] [4] The optical laminate as described in any one of [1] to [3] above, wherein the liquid crystal curing film is a film obtained by curing at least one compound having at least one maximum absorption in the wavelength range of 300 to 400 nm.

[0022] [5] The optical laminate as described in any one of [1] to [4] above, wherein the liquid crystal curing film satisfies the following formula (3):

[0023] 100nm≤Re(550)≤170nm (3)

[0024] [In the formula, Re(λ) represents the in-plane phase difference at wavelength λ].

[0025] [6] The optical laminate as described in any one of [1] to [5] above, wherein the aforementioned transparent protective film has a density of 100 g / m³. 2 / 24 hours or more of moisture permeability.

[0026] [7] The optical laminate as described in any one of [1] to [6] above, wherein the aforementioned adhesive layer is a layer formed by a dry curing adhesive.

[0027] [8] The optical laminate as described above in [7], wherein the aforementioned dry curing adhesive comprises polyvinyl alcohol.

[0028] [9] The optical laminate as described in any one of [1] to [8] above, wherein the phase difference film and the adhesive layer that bonds the phase difference film and the polarizer are in contact on the liquid crystal curing film side.

[0029]

[10] An optical laminate roll, which is formed by winding the optical laminate described in any one of [1] to [9] above.

[0030]

[11] An elliptical polarizing plate comprising any one of the optical laminates described in any one of [1] to [9].

[0031]

[12] An organic EL display device comprising the elliptical polarizing plate described above

[11] .

[0032]

[13] A flexible image display device comprising the elliptical polarizing plate described above

[11] .

[0033]

[14] The flexible image display device described above

[13] also includes a window and a touch sensor.

[0034] Invention Effects

[0035] According to the present invention, an optical laminate that is not prone to strain when bent, has high flexibility and excellent oblique reflectivity can be provided, especially an optical laminate suitable for flexible displays. Attached Figure Description

[0036] [ Figure 1 [A schematic cross-sectional view showing an example of the layer configuration of the optical laminate of the present invention.]

[0037] [ Figure 2 [A schematic cross-sectional view showing an example of the layer configuration of the optical laminate of the present invention.] Detailed Implementation

[0038] The embodiments of the present invention will now be described in detail. It should be noted that the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the invention.

[0039] The optical laminate of the present invention comprises a phase retardation film, a polarizer, and a transparent protective film in sequence, wherein the phase retardation film, the polarizer, and the transparent protective film are adjacent to each other with an adhesive layer between them.

[0040] (Adhesive layer)

[0041] In the optical laminate of the present invention, the retardation film and the polarizer, and the polarizer and the transparent protective film are each laminated with an adhesive layer. By bonding the retardation film and the polarizer, and the polarizer and the transparent protective film with adhesive layers, when the resulting optical laminate is repeatedly bent, it is assumed that the deformation in the liquid crystal curing film constituting the retardation film and the deformation of the optical laminate as a whole tend to follow each other, and strain relative to the bending point is less likely to occur. This can suppress stripe-like defects and the increase in oblique reflectivity caused by the aforementioned strain.

[0042] The adhesive layer for bonding the retardation film to the polarizer, and the polarizer to the transparent protective film, can be formed using an adhesive. Examples of adhesives capable of forming this adhesive layer include, for instance, water-based adhesives and other dry-curing adhesives, and chemically reactive adhesives such as active energy radiation-curing adhesives. The adhesive layers for bonding the retardation film to the polarizer, and the polarizer to the transparent protective film, can also be formed using different adhesives, but it is preferable that they are formed using the same adhesive.

[0043] Examples of dry-curing adhesives include compositions containing polymers or polyurethane resins as the main component, which are monomers having proton functional groups such as hydroxyl, carboxyl, or amino groups and olefinic unsaturated groups, and also contain crosslinking agents or curing compounds such as polyaldehydes, epoxy compounds, epoxy resins, melamine compounds, zirconium oxide compounds, and zinc compounds. Examples of polymers containing monomers having proton functional groups such as hydroxyl, carboxyl, or amino groups and olefinic unsaturated groups include ethylene-maleic acid copolymers, itaconic acid copolymers, acrylic acid copolymers, acrylamide copolymers, polyvinyl acetate saponifications, and polyvinyl alcohol resins.

[0044] Examples of polyvinyl alcohol (PVA)-based resins include polyvinyl alcohol, partially saponified PVA, fully saponified PVA, carboxyl-modified PVA, acetyl-modified PVA, hydroxymethyl-modified PVA, and amino-modified PVA. The content of PVA-based resin in water-based drying-curing adhesives is typically 1 to 10 parts by weight relative to 100 parts by weight of water, preferably 1 to 5 parts by weight.

[0045] Examples of polyurethane resins include polyester-based ion-crosslinked polymer polyurethane resins.

[0046] The polyester-based ion-crosslinked polymer polyurethane resin referred to here is a polyurethane resin with a polyester backbone, obtained by introducing a small amount of ionic components (hydrophilic components) into it. This ion-crosslinked polymer polyurethane resin emulsifies in water to form an emulsion without the use of an emulsifier, thus enabling the production of water-based, dry-curing adhesives. When using polyester-based ion-crosslinked polymer polyurethane resin, incorporating a water-soluble epoxy compound as a crosslinking agent is effective.

[0047] Examples of epoxy resins include polyamide epoxy resins obtained by reacting epichlorohydrin with polyamide polyamines (which are obtained by reacting polyalkylene polyamines such as diethylenetriamine or triethylenetetramine with dicarboxylic acids such as adipic acid). Commercially available examples of such polyamide epoxy resins include "Sumirez resin (registered trademark) 650" and "Sumirez resin (registered trademark) 675" (manufactured by Sumika Chemtex Co., Ltd.), and "WS-525" (manufactured by PMC Corporation of Japan). When incorporating epoxy resin, the amount added is typically 1 to 100 parts by weight, preferably 1 to 50 parts by weight, relative to 100 parts by weight of polyvinyl alcohol-based resin.

[0048] Among them, the dry-curing adhesive is preferably an aqueous dry-curing adhesive containing polyvinyl alcohol resin.

[0049] Dry-curing adhesives may contain solvents. Examples of solvents include water, mixtures of water and hydrophilic organic solvents (such as alcohol solvents, ether solvents, ester solvents, etc.), and organic solvents.

[0050] Reactive energy radiation-cured adhesives, as chemically reactive adhesives, are adhesives that cure upon exposure to reactive energy radiation. Reactive energy radiation-cured adhesives may contain solvents.

[0051] Examples of active energy radiation-cured adhesives include: cationic polymerizable adhesives containing epoxy compounds and cationic polymerization initiators; free radical polymerizable adhesives containing acrylic curing components and free radical polymerization initiators; adhesives containing both cationic polymerizable curing components such as epoxy compounds and free radical polymerizable curing components such as acrylic compounds, and also containing cationic polymerization initiators and free radical polymerization initiators; and adhesives that do not contain these polymerization initiators but are cured by irradiation with an electron beam.

[0052] Among these, the preferred active energy radiation-cured adhesives are those containing acrylic curing components and free radical polymerization initiators, exhibiting free radical polymerization properties, or those containing epoxy compounds and cationic polymerization initiators, exhibiting cationic polymerization properties. Examples of acrylic curing components include methyl methacrylate, hydroxyethyl methacrylate, and other methacrylates and methacrylic acid. Active energy radiation-cured adhesives containing epoxy compounds may also contain compounds other than epoxy compounds. Examples of compounds other than epoxy compounds include oxetane compounds and acrylic compounds.

[0053] Examples of free radical polymerization initiators include photopolymerization initiators described below, which can be incorporated into polymerizable liquid crystal compositions forming liquid crystal curable films. Commercially available cationic polymerization initiators include the "KAYARAD" (registered trademark) series (manufactured by Nippon Kayaku Co., Ltd.), the "Cyracure UVI" series (manufactured by Dow Chemical Company), the "CPI" series (manufactured by San-Apro Co., Ltd.), "TAZ," "BBI," and "DTS" (all manufactured by Midori Kagaku Co., Ltd.), the "ADEKA OPTOMER" series (manufactured by ADEKA Co., Ltd.), and "RHODORSIL" (registered trademark) (manufactured by Rhodia Co., Ltd.). The content of the free radical polymerization initiator and the cationic polymerization initiator is typically 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, relative to 100 parts by weight of the active energy ray-cured adhesive.

[0054] In an optical laminate formed by sequentially stacking a phase retardation film, a polarizer, and a transparent protective film, from the viewpoint of thinning the laminate and improving its flexibility, it is considered advantageous to use adhesives such as dry-curing adhesives and chemically reactive adhesives compared to pressure-sensitive adhesives made of high-viscosity materials. On the other hand, the optical laminate of the present invention includes a liquid crystal curing film exhibiting the optical properties represented by formulas (1) and (2) in a single layer. The polymeric liquid crystal compound forming such a liquid crystal curing film, as described later, generally has a large absorption wavelength in the range of 300 to 400 nm. In addition, the transparent protective film located on the viewing side when assembled into an image display device has ultraviolet absorption capability in order to protect the internal structure of the optical laminate from ultraviolet damage. Therefore, in the manufacture of such an optical laminate, sometimes the ultraviolet light irradiated is absorbed by the liquid crystal curing film and the transparent protective film, and a sufficient amount of ultraviolet light is difficult to reach the interior of the laminate for the curing of the adhesive. Therefore, in the optical laminate of the present invention, which may be sandwiched between layers with ultraviolet absorption capabilities (liquid crystal curing film and transparent protective film), it is advantageous to use a dry-curing adhesive as the adhesive for bonding the retardation film to the polarizer and the polarizer to the transparent protective film, from the viewpoints of thinning, improved flexibility, and obtaining an optical laminate with better interlayer adhesion.

[0055] The thickness of the adhesive layer bonding the retardation film to the polarizer and the polarizer to the transparent protective film is preferably 10 nm or more, more preferably 30 nm or more, even more preferably 50 nm or more, preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 2 μm or less. If the thickness of the adhesive layer is within the above range, strain at the bending point is less likely to occur under repeated bending, thus easily suppressing the generation of stripe-like defects and the increase in oblique reflectivity. The thickness of the adhesive layer bonding the retardation film to the polarizer and the polarizer to the transparent protective film can be the same or different from each other.

[0056] The thickness of the adhesive layer can be measured using instruments such as an interferometer, laser microscope, or stylus thickness gauge.

[0057] (Phase difference film)

[0058] The phase retardation film constituting the optical stack of the present invention comprises having a concentration of 100 g / m 2 A substrate film with a moisture permeability of at least 24 hours, and a liquid crystal cured film formed on the substrate film. The moisture permeability of the substrate film is preferably 150 g / m³. 2 / 24 hours or more, preferably 200g / m 2 / 24 hours or more. If the moisture permeability of the substrate film constituting the retardation film is above the lower limit mentioned above, it becomes easier to control the moisture composition in the optical laminate formed by stacking the retardation film and the polarizer. Especially when using a drying-curing adhesive as the adhesive layer, it is easy to remove the solvent from the adhesive and to prepare an adhesive layer with physical properties similar to the elasticity and flexibility of the liquid crystal cured film formed on the substrate film. Therefore, when bending the optical laminate, the adhesive layer that bonds each layer is less likely to affect the deformation in the liquid crystal cured film, and the overall deformation of the optical laminate and the deformation in each layer are more likely to follow each other. Thus, even under repeated bending, strain at the bending point is less likely to occur, and the resulting stripe-like defects and increase in oblique reflectivity can be suppressed. The upper limit of the moisture permeability of the substrate film is not particularly limited, but is usually 1000 g / m³. 2 / less than 24 hours, preferably 500g / m 2 / less than 24 hours.

[0059] It should be noted that the moisture permeability of the substrate film can be measured, for example, according to JIS Z 0208 (cup method). More specifically, it can be measured according to the method described in the examples below.

[0060] The moisture permeability of the substrate membrane can be controlled by the type of resin that makes up the membrane, the thickness of the membrane, and the surface treatment.

[0061] As a component with 100g / m 2 Resins for substrate films with a moisture permeability of 24 hours or more include, for example, cellulose triacetate, polyvinylpyrrolidone polymers, and (meth)acrylamide polymers. From the viewpoint of ease of acquisition, cellulose triacetate is preferred. Such resins can be used to form films using known methods such as solvent casting and melt extrusion. Alternatively, commercially available products can also be used.

[0062] The thickness of the substrate film can be appropriately determined according to the desired optical laminate composition. From the viewpoint of thinness, processability, flexibility and strength of the optical laminate, it is usually 5μm to 300μm, preferably 15μm to 200μm, and more preferably 20μm to 150μm.

[0063] The substrate film preferably has a total light transmittance of 90% or more, more preferably 92% or more. If the total light transmittance is above the lower limit mentioned above, an optical laminate with high transparency and excellent optical properties can be formed. The upper limit of the total light transmittance in the substrate film is not particularly limited, and it can be 100% or less. The total light transmittance can be measured, for example, according to JIS K7361.

[0064] For the substrate film, the absolute value of the phase difference Rth(550) in the thickness direction for 550nm light is preferably 5nm or less, more preferably 3nm or less. By controlling the phase difference value in the thickness direction of the substrate film, the desired optical properties due to the liquid crystal curing film are less likely to be affected, and the oblique reflectivity of the resulting optical laminate can be suppressed to a low level. When such an optical laminate is assembled into a display device, it exhibits excellent suppression of light leakage and hue changes during black display, thus becoming an optical laminate with advantageous optical properties. The smaller the aforementioned phase difference value Rth(550) of the substrate film, the better; it can also be 0nm. The phase difference value Rth(550) of the substrate film can be controlled not only by the addition of additives but also by casting methods, etc.

[0065] For the surface of the substrate film, depending on the composition of the liquid crystal curing film to be formed, the alignment film, and the adhesive that can be bonded to the substrate film, surface treatments such as corona treatment and plasma treatment may be performed to improve the adhesion to them.

[0066] In this invention, the liquid crystal curing film constituting the phase difference film is a single-layer liquid crystal curing film that satisfies the following formulas (1) and (2).

[0067] Re(450) / Re(550)≤1.00 (1)

[0068] 1.00≤Re(650) / Re(550) (2)

[0069] [In the formula, Re(λ) represents the in-plane phase difference at wavelength λ]

[0070] The term "satisfying with a single layer" means that a single-layer cured film obtained from a polymeric liquid crystal compound containing a liquid crystal compound exhibits the optical properties represented by the above formulas (1) and (2) in a single layer.

[0071] When a liquid crystal curing film satisfies equations (1) and (2), it exhibits so-called inverse wavelength dispersivity, meaning that the in-plane phase difference at shorter wavelengths is less than the in-plane phase difference at longer wavelengths. When exhibiting inverse wavelength dispersivity, there is a tendency to readily achieve the same phase difference performance over a wider wavelength range of visible light, and the optical properties of the optical laminate are easily improved. By using a liquid crystal curing film (hereinafter also referred to as "liquid crystal curing film (x)") having optical properties that satisfy the above equations (1) and (2) in a single layer, it is possible to obtain a thinner phase difference film with excellent optical properties.

[0072] In order to improve the reverse wavelength dispersion and thus further improve the effect of improving the reflectance hue in the front direction of the liquid crystal curable film, Re(450) / Re(550) is preferably 0.70 or more, more preferably 0.78 or more, and preferably 0.95 or less, more preferably 0.92 or less. In addition, Re(650) / Re(550) is preferably 1.0 or more, more preferably 1.01 or more, and even more preferably 1.02 or more.

[0073] The aforementioned in-plane phase difference value can be adjusted by the thickness d1 of the liquid crystal curing film. The in-plane phase difference value of the liquid crystal curing film is determined by Re = (nx(λ) - ny(λ)) × d (where d represents the thickness of the liquid crystal curing film, nx represents the principal refractive index at wavelength λnm in the direction parallel to the plane of the liquid crystal curing film in the refractive index ellipsoid formed by the liquid crystal curing film, and ny represents the refractive index at wavelength λnm in the direction parallel to the plane of the liquid crystal curing film and orthogonal to the aforementioned nx direction in the refractive index ellipsoid formed by the liquid crystal curing film). Therefore, in order to obtain the desired in-plane phase difference value, the three-dimensional refractive index and the film thickness d can be adjusted.

[0074] Furthermore, the liquid crystal curing film (x) preferably satisfies the following formula (3):

[0075] 100nm≤Re(550)≤170nm (3)

[0076] [In the formula, Re(λ) represents the in-plane phase difference at wavelength λ].

[0077] If the liquid crystal curing film (x) satisfies equation (3), it is easy to improve the front reflection hue when the optical stack (elliptical polarizing plate) containing the liquid crystal curing film (x) is applied to an organic EL display device. A further preferred range for the in-plane phase difference value is 130nm ≤ ReA(550) ≤ 150nm.

[0078] In this invention, the liquid crystal cured film (x) can be formed from a cured polymeric liquid crystal composition comprising at least one polymeric liquid crystal compound. As for the polymeric liquid crystal compound, there are no particular limitations as long as it can form a liquid crystal cured film with the desired optical properties; polymeric liquid crystal compounds conventionally known in the field of retardation films can be used.

[0079] Polymerizable liquid crystal compounds are liquid crystal compounds having polymerizable groups. Examples of polymerizable liquid crystal compounds include polymerizable liquid crystal compounds that exhibit positive wavelength dispersion and polymerizable liquid crystal compounds that exhibit reverse wavelength dispersion, obtained by polymerizing the polymerizable liquid crystal compound alone in a state of orientation along a specific direction. From the viewpoint of easily obtaining liquid crystal cured films that individually satisfy the optical properties represented by the above formulas (1) and (2), in the present invention, the liquid crystal cured film (x) constituting the retardation film is preferably a cured film containing a polymerizable liquid crystal composition of a polymerizable liquid crystal compound that exhibits reverse wavelength dispersion, obtained by polymerizing the polymer (cured product) alone in a state of orientation along a specific direction.

[0080] The term "polymerizable group" refers to a group capable of participating in a polymerization reaction. In this invention, the polymerizable group possessed by the polymerizable liquid crystal compound forming the liquid crystal curable film is preferably a photopolymerizable group. A photopolymerizable group refers to a polymerizable group capable of participating in a polymerization reaction using reactive species generated by a photopolymerization initiator, such as active free radicals or acids. Examples of photopolymerizable groups include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloxy, oxetylpropyl, and oxetylbutyl. Acryloyloxy, methacryloxy, vinyloxy, oxetylpropyl, and oxetylbutyl are preferred, and acryloyloxy is more preferred.

[0081] The liquid crystal properties exhibited by the polymerizable liquid crystal compound can be thermotropic or lyotropic, but thermotropic liquid crystals are preferred from the perspective of enabling precise film thickness control. Furthermore, the ordered phase structure in the thermotropic liquid crystal can be nematic, smectic, or disk-shaped. Two or more polymerizable liquid crystal compounds can be used alone or in combination.

[0082] Polymer liquid crystal compounds with so-called T-shaped or H-shaped molecular structures tend to exhibit reverse wavelength dispersion, with T-shaped molecular structures exhibiting a stronger tendency to exhibit reverse wavelength dispersion.

[0083] As a polymeric liquid crystal compound exhibiting reverse wavelength dispersion, a compound having the characteristics described in (A) to (D) below is preferred.

[0084] (A) is a compound that can form a nematic or smectic phase.

[0085] (B) The polymeric liquid crystal compound has π electrons in the long axis direction (a).

[0086] (C) It has π electrons in the direction intersecting the major axis direction (a) [intersecting direction (b)].

[0087] (D) Let the total number of π electrons present in the long axis direction (a) be N(πa), and the total number of molecular weights present in the long axis direction be N(Aa). The π electron density in the long axis direction (a) of the polymeric liquid crystal compound is defined by the following formula (i):

[0088] D(πa)=N(πa) / N(Aa)(i), and

[0089] Let N(πb) be the total number of π electrons present in the cross direction (b) and N(Ab) be the total number of molecular weights present in the cross direction (b). The π electron density in the cross direction (b) of the polymeric liquid crystal compound is defined by the following formula (ii):

[0090] D(πb)=N(πb) / N(Ab) (ii)

[0091] The relationship in equation (iii) exists [that is, the π electron density in the cross direction (b) is greater than the π electron density in the major axis direction (a)].

[0092] 0≤〔D(πa) / D(πb)〕<1 (iii)

[0093] As described above, polymeric liquid crystal compounds with π electrons along their long axis and in the direction intersecting it tend to form T-shaped structures.

[0094] Among the features (A) to (D) above, the major axis direction (a) and the number of π electrons N are defined as follows.

[0095] • For the long axis direction (a), for example, in the case of a compound with a rod-like structure, it is the long axis direction of the rod.

[0096] The number of π electrons N(πa) present in the long axis direction (a) does not include π electrons that disappear through polymerization.

[0097] The number of π electrons N(πa) present in the major axis direction (a) is the total number of π electrons in the major axis and their conjugate π electrons, for example, the number of π electrons present in the rings present in the major axis direction (a) and satisfying Hückel's rule.

[0098] The number of π electrons N(πb) present in the cross direction (b) does not include π electrons that disappear through the polymerization reaction.

[0099] Polymerizable liquid crystal compounds that meet the above conditions have a mesocrystalline structure along their long axis. This mesocrystalline structure enables them to exhibit a liquid crystal phase (nematic phase, smectic phase).

[0100] By heating the polymeric liquid crystal compound satisfying (A) to (D) above its phase transition temperature, a nematic or smectic phase can be formed. In the nematic or smectic phase formed by aligning the polymeric liquid crystal compound, the polymeric liquid crystal compound is typically aligned with each other in a manner parallel to its long axis, which becomes the orientation direction of the nematic or smectic phase. If such a polymeric liquid crystal compound is formed into a film and polymerized in a nematic or smectic state, a polymer film composed of a polymer polymerized in a state aligned along its long axis (a) can be formed. This polymer film absorbs ultraviolet light using π electrons in the long axis direction (a) and π electrons in the cross direction (b). Here, the wavelength of maximum absorption of ultraviolet light absorbed by π electrons in the cross direction (b) is set as λbmax. λbmax is typically 300 nm to 400 nm. The density of π electrons satisfies equation (iii) above. The density of π electrons in the cross direction (b) is greater than that in the major axis direction (a). Therefore, the polymer film exhibits greater absorption of linearly polarized ultraviolet light (wavelength λbmax) with a vibrational surface in the cross direction (b) than with linearly polarized ultraviolet light (wavelength λbmax) with a vibrational surface in the major axis direction (a). This ratio (absorbance of linearly polarized ultraviolet light in the cross direction (b) / absorbance in the major axis direction (a)) is, for example, greater than 1.0, preferably 1.2 or more, typically 30 or less, and for example, 10 or less.

[0101] Polymerizable liquid crystal compounds with the above characteristics are generally polymerizable liquid crystal compounds in which the birefringence of the polymer exhibits reverse wavelength dispersion when polymerized in a state oriented in one direction. Specifically, for example, compounds represented by the following formula (X) (hereinafter also referred to as "polymerizable liquid crystal compound (X)") can be cited.

[0102] [Chemical Formula 1]

[0103]

[0104] In formula (X), Ar represents a divalent group having an aromatic group that may have substituents. The aromatic group referred to here includes, for example, the groups exemplified in (Ar-1) to (Ar-23) described later. Furthermore, Ar may have two or more aromatic groups. These aromatic groups may contain at least one of a nitrogen atom, an oxygen atom, or a sulfur atom. When Ar contains two or more aromatic groups, these two or more aromatic groups may be bonded to each other through single bonds, -CO-O-, -O-, or other divalent bonding groups.

[0105] G 1 and G 2Each of these can be independently represented as a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group can be replaced by a halogen atom, an alkyl group with 1 to 4 carbon atoms, a fluoroalkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, a cyano group, or a nitro group, and the carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group can be replaced by an oxygen atom, a sulfur atom, or a nitrogen atom.

[0106] L 1 L 2 B 1 and B 2 Each is an independent linking group that is either a single bond or divalent.

[0107] k and l each independently represent integers from 0 to 3, satisfying the relation 1 ≤ k + l. Here, in the case of 2 ≤ k + l, B 1 and B 2 G 1 and G 2 They can be the same as each other, or they can be different.

[0108] E 1 and E 2 Each alkane dimethyl group independently represents an alkane with 1 to 17 carbon atoms, more preferably an alkane dimethyl group with 4 to 12 carbon atoms. In addition, the hydrogen atoms contained in the alkane dimethyl group can be replaced by halogen atoms, and the -CH2- contained in the alkane dimethyl group can be replaced by -O-, -S-, or -C(=O)-.

[0109] P 1 and P 2 Each of the above represents a polymeric group or a hydrogen atom independently, with at least one being a polymeric group.

[0110] G 1 and G 2 Each of the following is preferably 1,4-phenylenediyl group, which can be substituted with at least one substituent selected from the group consisting of alkyl groups with 1 to 4 carbon atoms; or 1,4-cyclohexanediyl group, which can be substituted with at least one substituent selected from the group consisting of alkyl groups with 1 to 4 carbon atoms; more preferably methyl-substituted 1,4-phenylenediyl group, unsubstituted 1,4-phenylenediyl group, or unsubstituted 1,4-trans-cyclohexanediyl group; and particularly preferably unsubstituted 1,4-phenylenediyl group or unsubstituted 1,4-trans-cyclohexanediyl group.

[0111] In addition, it is preferable that there are multiple Gs. 1 and G 2 At least one of them is a divalent alicyclic hydrocarbon group, and more preferably it is with L 1 or L2 bonded G 1 and G 2 At least one of them is a divalent alicyclic hydrocarbon group.

[0112] L 1 and L 2 Each is preferably a single bond, an alkylene group having 1 to 4 carbon atoms, or an -O-, -S-, or -R group. a1 OR a2 -、-R a3 COOR a4 -、-R a5 OCOR a6 -、-R a7 OC = OOR a8 -、-N=N-、-CR c =CR d -、or -C≡C-. Here, R a1 ~R a8 Each independently represents a single bond, or an alkylene group having 1 to 4 carbon atoms, R c and R d L represents an alkyl group or hydrogen atom with 1 to 4 carbon atoms. 1 and L 2 Each independently is more preferably a single bond, -OR a2-1 -、-CH2-、-CH2CH2-、-COOR a4-1 -、or-OCOR a6-1 -. Here, R a2-1 R a4-1 R a6-1 Each can independently represent any one of a single bond, -CH2-, or -CH2CH2-. L 1 and L 2 Each of these can be further preferred independently as a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, or -OCO-.

[0113] B 1 and B 2 Each is preferably a single bond, an alkylene group having 1 to 4 carbon atoms, or an -O-, -S-, or -R group. a9 OR a10 -、-R a11 COOR a12 -、-R a13 OCOR a14 - or -R a15 OC = OOR a16 -. Here, R a9 ~R a16 Each can independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B 1 and B2 Each independently is more preferably a single bond, -OR a10-1 -、-CH2-、-CH2CH2-、-COOR a12 -1 -、or-OCOR a14-1 -. Here, R a10-1 R a12-1 R a14-1 Each can independently represent any one of a single bond, -CH2-, or -CH2CH2-. B 1 and B 2 Each of these can be further preferred independently as a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, -OCO-, or -OCOCH2CH2-.

[0114] From the viewpoint of exhibiting inverse wavelength dispersion, k and l are preferably in the range of 2 ≤ k + l ≤ 6, preferably k + l = 4, and more preferably k = 2 and l = 2. If k = 2 and l = 2, it becomes a symmetrical structure, and is therefore preferred.

[0115] As P 1 or P 2 Examples of polymerizable groups include epoxy, vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, oxetylpropyl, and oxetylbutyl.

[0116] Preferably, it is acryloyloxy, methacryloyloxy, vinyl and vinyloxy, and more preferably acryloyloxy and methacryloyloxy.

[0117] Ar preferably has at least one group selected from aromatic hydrocarbon rings that may have substituents, aromatic heterocycles that may have substituents, and electron-withdrawing groups. Examples of such aromatic hydrocarbon rings include benzene rings, naphthyl rings, and anthracene rings, with benzene rings and naphthyl rings being preferred. Examples of such aromatic heterocycles include furan rings, benzofuran rings, pyrrole rings, indole rings, thiophene rings, benzothiophene rings, pyridine rings, pyrazine rings, pyrimidine rings, triazole rings, triazine rings, pyrrolidine rings, imidazole rings, pyrazole rings, thiazole rings, benzothiazole rings, thienothiazole rings, oxazole rings, benzoxazole rings, and phenanthroline rings. Among these, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferred, and a benzothiazole ring is even more preferred. Furthermore, when Ar contains a nitrogen atom, the nitrogen atom preferably has π electrons.

[0118] In formula (X), N represents the total number of π electrons possessed by the group represented by Ar. πThe value is typically 6 or more, preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. Additionally, it is preferably 32 or less, more preferably 26 or less, and even more preferably 24 or less.

[0119] The following groups can be cited as examples of aromatic groups contained in Ar.

[0120] [Chemical Formula 2]

[0121]

[0122] In equations (Ar-1) to (Ar-23), the symbol * represents the connecting part, and Z 0 Z 1 and Z 2 Each of these groups independently represents a hydrogen atom, a halogen atom, an alkyl group (1-12 carbon atoms), a cyano group, a nitro group, an alkyl sulfinyl group (1-12 carbon atoms), an alkyl sulfonyl group (1-12 carbon atoms), a carboxyl group, a fluoroalkyl group (1-12 carbon atoms), an alkoxy group (1-12 carbon atoms), an alkyl thio group (1-12 carbon atoms), an N-alkylamino group (1-12 carbon atoms), an N,N-dialkylamino group (2-12 carbon atoms), an N-alkylaminosulfonyl group (1-12 carbon atoms), or an N,N-dialkylaminosulfonyl group (2-12 carbon atoms). Additionally, Z... 0 Z 1 and Z 2 It can contain polymeric groups.

[0123] Q 1 and Q 2 Each is represented independently - CR 2’ R 3’ -、-S-、-NH-、-NR 2’ -、-CO- or -O-, R 2’ and R 3’ Each can be independently represented as an alkyl group having 1 to 4 hydrogen atoms or carbon atoms.

[0124] J 1 and J 2 Each can be used to represent a carbon atom or a nitrogen atom independently.

[0125] Y 1 Y 2 and Y 3 Each can be independently represented as a substituted aromatic hydrocarbon group or an aromatic heterocyclic group.

[0126] W 1 and W 2 Each can independently represent a hydrogen atom, cyano group, methyl group, or halogen atom, and m represents an integer from 0 to 6.

[0127] As Y1 Y 2 and Y 3 The aromatic hydrocarbon group in the form of the aromatic hydrocarbon group can include phenyl, naphthyl, anthraceneyl, phenanthryl, biphenyl, etc., which have 6 to 20 carbon atoms, preferably phenyl or naphthyl, and more preferably phenyl. As an aromatic heterocyclic group, examples include furanyl, pyrroleyl, thiopheneyl, pyridyl, thiazolyl, benzothiazolyl, etc., which have 4 to 20 carbon atoms and contain at least one heteroatom such as a nitrogen atom, oxygen atom, or sulfur atom, preferably furanyl, thiopheneyl, pyridyl, thiazolyl, or benzothiazolyl.

[0128] Y 1 Y 2 and Y 3 Each can be independently a substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. A polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. A polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

[0129] Z 0 Z 1 and Z 2 Each of the following is preferably composed of a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms. 0 Further preferred are hydrogen atoms, alkyl groups having 1 to 12 carbon atoms, and cyano groups, Z. 1 and Z 2 Further preferred are hydrogen atoms, fluorine atoms, chlorine atoms, methyl groups, and cyano groups. Additionally, Z... 0 Z 1 and Z 2 It can contain polymeric groups.

[0130] Q 1 and Q 2 Preferred types are -NH-, -S-, and -NR. 2’ -、-O-,R 2’ Hydrogen atoms are preferred. Among them, -S-, -O-, and -NH- are particularly preferred.

[0131] Of the formulas (Ar-1) to (Ar-23), formulas (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.

[0132] In equations (Ar-16) to (Ar-23), Y 1 It can bond with the nitrogen atom and Z 0Together, they form an aromatic heterocyclic group. Examples of aromatic heterocyclic groups include those described above that can be present in Ar, such as pyrrole rings, imidazole rings, pyrrolidine rings, pyrrololine rings, pyridine rings, pyrazine rings, pyrimidine rings, indole rings, quinoline rings, isoquinoline rings, purine rings, and pyrrolidine rings. This aromatic heterocyclic group may have substituents. Additionally, Y... 1 It can bond with the nitrogen atom and Z 0 Together, these are the aforementioned substituted polycyclic aromatic hydrocarbon groups or polycyclic aromatic heterocyclic groups. Examples include benzofuran rings, benzothiazole rings, and benzoxazole rings.

[0133] In this invention, the liquid crystal cured film (x) constituting the phase retardation film preferably has at least one maximum absorption wavelength between 300 and 400 nm, and the polymeric liquid crystal compound forming the liquid crystal cured film (x) is preferably a polymeric liquid crystal compound having a maximum absorption wavelength between 300 and 400 nm. When the polymeric liquid crystal composition contains a photopolymerization initiator, there are concerns about polymerization and gelation of the polymeric liquid crystal compound during long-term storage. However, if the maximum absorption wavelength of the polymeric liquid crystal compound is 300-400 nm, even when exposed to ultraviolet light during storage, the generation of reactive species from the photopolymerization initiator and the polymerization and gelation of the polymeric liquid crystal compound caused by these reactive species can be effectively suppressed. Therefore, this becomes advantageous in terms of the long-term stability of the polymeric liquid crystal composition, and the orientation and thickness uniformity of the obtained liquid crystal cured film can be improved. It should be noted that the maximum absorption wavelength of the polymeric liquid crystal compound can be measured using a UV-Vis spectrophotometer in a solvent. The solvent is one that can dissolve polymeric liquid crystal compounds, such as chloroform and tetrahydrofuran.

[0134] Specifically, examples of polymeric liquid crystal compounds capable of forming liquid crystal cured films (x) include those described in Japanese Patent Application Publication No. 2011-207765 and Japanese Patent Application Publication No. 2010-031223. Furthermore, polymeric liquid crystal compounds exhibiting positive wavelength dispersion as homopolymers can be used as long as a liquid crystal cured film (x) satisfying the above formulas (1) and (2) in a monolayer can be formed.

[0135] Regarding the content of the polymeric liquid crystal compound in the polymeric liquid crystal composition used to form the liquid crystal cured film (x), it is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and even more preferably 90 to 95 parts by mass, relative to 100 parts by mass of the solid component of the polymeric liquid crystal composition. If the content of the polymeric liquid crystal compound is within the above range, it is advantageous from the viewpoint of the orientation of the obtained liquid crystal cured film (x). It should be noted that, in this specification, the term "solid component of the polymeric liquid crystal composition" refers to all components obtained by removing volatile components such as organic solvents from the polymeric liquid crystal composition.

[0136] The polymeric liquid crystal composition used to form the liquid crystal cured film (x) may contain, in addition to the polymeric liquid crystal compound, additives such as solvents, polymerization initiators, leveling agents, antioxidants, photosensitizers, and reactive additives. Only one of these components may be used, or two or more may be used in combination.

[0137] Polymerizable liquid crystal compositions are typically coated onto substrate films or the like in a solvent-dissolved state, therefore the presence of a solvent is preferred. As a solvent, a solvent that can dissolve the polymerizable liquid crystal compound but is inactive for the polymerization reaction of the liquid crystal compound is preferred. Furthermore, a solvent that will not dissolve the substrate film used is preferred. Examples of solvents include, for example, water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene, xylene, and anisole; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; and amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone (NMP), and 1,3-dimethyl-2-imidazolinone. These solvents can be used alone or in combination of two or more. From the viewpoint of film coating, it is preferable to use at least one solvent selected from alcohol solvents, ester solvents, ketone solvents, chlorinated solvents, amide solvents, and aromatic hydrocarbon solvents. From the viewpoint of the solubility of polymerizable liquid crystal compounds, it is more preferable to use at least one solvent selected from ester solvents, ketone solvents, amide solvents, and aromatic hydrocarbon solvents.

[0138] The solvent content in the polymeric liquid crystal composition is preferably 50 to 98 parts by weight, more preferably 70 to 95 parts by weight, relative to 100 parts by weight of the polymeric liquid crystal composition. Therefore, the solid component preferably accounts for 2 to 50 parts by weight of the polymeric liquid crystal composition. If the solid component is 50 parts by weight or less, the viscosity of the polymeric liquid crystal composition becomes lower, and thus the film thickness becomes approximately uniform, with a tendency to avoid unevenness. The above-mentioned solid component can be suitably determined considering the thickness of the polymeric liquid crystal cured film to be manufactured.

[0139] Polymerization initiators are compounds that can generate reactive species through the action of heat or light, thereby initiating polymerization reactions of polymerizable liquid crystal compounds, etc. Examples of reactive species include free radicals, cationic or anionic species. From the viewpoint of easy reaction control, photopolymerization initiators that generate free radicals through light irradiation are preferred.

[0140] Examples of photopolymerization initiators include benzoin compounds, benzophenone compounds, benzoyl ketal compounds, oxime compounds, α-hydroxy ketone compounds, α-amino ketone compounds, triazine compounds, iodonium salts, and sulfonium salts; commercially available products may also be used. Specifically, examples include Irgacure (イルガキュア, registered trademark) 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369, Irgacure 379, Irgacure 127, Irgacure 2959, Irgacure 754, Irgacure 379EG (all manufactured by BASF Japan Ltd.), SEIKUOLBZ, SEIKUOL Z, SEIKUOL BEE (all manufactured by Seiko Chemical Co., Ltd.), kayacure (カヤキュアー) BP100 (manufactured by Nippon Kayaku Co., Ltd.), kayacure UVI-6992 (manufactured by DOW Corporation), ADEKA OPTOMER SP-152, and ADEKA. OPTOMER SP-170, ADEKA OPTOMER N-1717, ADEKA OPTOMER N-1919, ADEKA ARKLS NCI-831, ADEKA ARKLS NCI-930 (all manufactured by ADEKA Co., Ltd.), TAZ-A, TAZ-PP (all manufactured by Nihon Siber Hegner KK), and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.), etc.

[0141] The polymerizable liquid crystal composition contains at least one photopolymerization initiator, or multiple initiators in combination, which can be appropriately selected based on their relationship with the polymerizable liquid crystal compounds contained in the polymerizable liquid crystal composition.

[0142] Photopolymerization initiators can fully and effectively utilize the energy emitted from the light source and have excellent productivity. Therefore, the maximum absorption wavelength is preferably 300nm to 400nm, more preferably 300nm to 380nm, and preferably α-acetophenone-based polymerization initiators or oxime-based photopolymerization initiators.

[0143] Examples of α-acetophenone compounds include 2-methyl-2-morpholino-1-(4-methylthioalkylphenyl)propane-1-one, 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutane-1-one, and 2-dimethylamino-1-(4-morpholinophenyl)-2-(4-methylphenylmethyl)butane-1-one, with 2-methyl-2-morpholino-1-(4-methylthioalkylphenyl)propane-1-one and 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutane-1-one being more preferred. Commercially available α-acetophenone compounds include Irgacure 369, 379EG, 907 (all manufactured by BASF Japan Ltd.) and SEIKUOLBEE (manufactured by Seiko Chemical Co., Ltd.).

[0144] Oxime ester-based photopolymerization initiators can generate free radicals such as phenyl radicals and methyl radicals by irradiation. The polymerization of polymerizable liquid crystal compounds can be suitably carried out via these free radicals. Oxime ester-based photopolymerization initiators that generate methyl radicals are preferred due to their high initiation efficiency. Furthermore, from the viewpoint of making the polymerization reaction even more efficient, photopolymerization initiators that can efficiently utilize ultraviolet light with wavelengths of 350 nm or higher are preferred. As photopolymerization initiators that can efficiently utilize ultraviolet light with wavelengths of 350 nm or higher, triazine compounds or carbazole compounds containing an oxime ester structure are preferred; from the viewpoint of sensitivity, carbazole compounds containing an oxime ester structure are more preferred. Examples of carbazole compounds containing an oxime ester structure include 1-[4-(phenylthio)-1,2-octanedione 2-(O-benzoyl oxime)] and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] acetophenone-1-(O-acetyl oxime). Commercially available oxime ester-based photopolymerization initiators include Irgacure OXE-01, Irgacure OXE-02, Irgacure OXE-03 (all manufactured by BASF Japan Ltd.), ADEKA OPTOMER N-1919, and ADEKA ARKLS NCI-831 (all manufactured by ADEKA Corporation).

[0145] The content of the photopolymerization initiator is typically 0.1 to 30 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, preferably 1 to 20 parts by mass, and more preferably 1 to 15 parts by mass. Within these ranges, the reaction of the polymerizable groups proceeds sufficiently, and the orientation of the polymerizable liquid crystal compound is not easily disturbed.

[0146] Leveling agents are additives that adjust the flowability of polymerizable liquid crystal compositions and make the resulting coating smoother. Examples of leveling agents include silicone-based, polyacrylate-based, and perfluoroalkyl-based agents.Commercially available products can also be used as leveling agents, specifically including DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, and FZ2123 (all of which are Dow Corning Toray). (Manufactured by Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341, X22-161A, KF6001 (all manufactured by Shin-Etsu Chemical Industry Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (all manufactured by Momentive Advanced Materials Japan Contract Co., Ltd.), fluorinert (registered trademark) FC-72, fluorinert FC-40, fluorinert FC-43, fluorinert FC-3283 (all manufactured by Sumitomo 3MLtd.), MEGAFACE (registered trademark) R-08, MEGAFACE R-30, MEGAFACE R-90, MEGAFACE F-410, MEGAFACE F-411, MEGAFACE F-443, MEGAFACE F-445, MEGAFACE F-470, MEGAFACE F-477, MEGAFACE F-479, MEGAFACE F-482, MEGAFACE F-483, MEGAFACE F-556 (all manufactured by DIC Co., Ltd.), F-top (trade name) EF301, F-top EF303, F-top EF351, F-top EF352 (all manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Surflon (registered trademark) S-381, Surflon S-382, Surflon S-383, Surflon S-393, Surflon SC-101, Surflon SC-105, KH-40, SA-100 (all manufactured by AGC Seimi Chemical Co., Ltd.), trade name E1830, trade name E5844 (manufactured by Daikin Fine Chemical Kenkyusho, KK), BM-1000, BM-1100, BYK-352, BYK-353, and BYK-361N (all manufactured by BM Chemie), etc. Leveling agents can be used alone or in combination of two or more.

[0147] The leveling agent content is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, and more preferably 0.05 to 3 parts by mass. If the leveling agent content is within the above range, there is a tendency to easily orient the polymerizable liquid crystal compound and make the resulting liquid crystal cured film smoother, which is therefore preferred.

[0148] By combining antioxidants, the polymerization reaction of polymerizable liquid crystal compounds can be controlled. The antioxidants can be primary antioxidants selected from phenolic, amine, quinone, and nitroso antioxidants, or secondary antioxidants selected from phosphorus and sulfur antioxidants.

[0149] In order to polymerize the polymerizable liquid crystal compound without disturbing its orientation, the content of antioxidant is typically 0.01 to 10 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass.

[0150] Antioxidants can be used alone or in combination of two or more.

[0151] By using a photosensitizer, the sensitivity of the photopolymerization initiator can be increased. Examples of photosensitizers include xanthones such as xanthone and thioxanthone; anthracene derivatives with substituents such as anthracene and alkyl ethers; phenothiazines; and rubrene. Two or more photosensitizers can be used alone or in combination. The content of the photosensitizer is typically 0.01 to 10 parts by weight relative to 100 parts by weight of the polymerizable liquid crystal compound, preferably 0.05 to 5 parts by weight, and more preferably 0.1 to 3 parts by weight.

[0152] By using reactive additives, the adhesion between the substrate film and the liquid crystal curable film, as well as the adhesion between the phase retardation film and the adhesive layer, can be improved. As reactive additives, substances having carbon-carbon unsaturated bonds and active hydrogen reactive groups within their molecules are preferred. It should be noted that the term "active hydrogen reactive group" here refers to a group reactive to groups containing active hydrogen, such as carboxyl (-COOH), hydroxyl (-OH), and amino (-NH2). Glycidyl groups, oxazoline groups, carbodiimide groups, aziridinyl groups, imide groups, isocyanate groups, isothiocyanate groups, and maleic anhydride groups are representative examples. The number of carbon-carbon unsaturated bonds or active hydrogen reactive groups in the reactive additive is typically 1 to 20, preferably 1 to 10 each.

[0153] In reactive additives, it is preferable to have at least two active hydrogen reactive groups. In this case, the presence of multiple active hydrogen reactive groups may be the same or different.

[0154] The carbon-carbon unsaturated bonds in the reactive additive can be carbon-carbon double bonds, carbon-carbon triple bonds, or combinations thereof, but carbon-carbon double bonds are preferred. Specifically, as a reactive additive, carbon-carbon unsaturated bonds are preferably contained in the form of vinyl and / or (meth)acrylic acid groups. Furthermore, reactive additives whose active hydrogen reactive groups are at least one selected from the group consisting of epoxy groups, glycidyl groups, and isocyanate groups are preferred, and reactive additives having acrylic acid groups and isocyanate groups are more preferred.

[0155] Specific examples of reactive additives include compounds such as methacryloxyglycidyl ether and acryloxyglycidyl ether, which have (meth)acrylic acid groups and epoxy groups; compounds such as oxetane acrylate and oxetane methacrylate, which have (meth)acrylic acid groups and oxetane butyl groups; compounds such as lactone acrylate and lactone methacrylate, which have (meth)acrylic acid groups and lactone groups; compounds such as vinyl oxazoline and isopropenyl oxazoline, which have vinyl and oxazoline groups; and oligomers of compounds such as methyl isocyanate acrylate, methyl isocyanate methacrylate, ethyl 2-isocyanate acrylate, or ethyl 2-isocyanate methacrylate, which have (meth)acrylic acid groups and isocyanate groups. Additionally, compounds such as methacrylic anhydride, acrylic anhydride, maleic anhydride, or vinyl maleic anhydride, which have vinyl, vinylidene, and anhydride groups, can be cited. Preferably, the oligomers are methacryloyloxyglycidyl ether, acryloyloxyglycidyl ether, methyl isocyanate acrylate, methyl isocyanate methacrylate, vinyloxazoline, ethyl 2-isocyanate acrylate, ethyl 2-isocyanate methacrylate, or the oligomers thereof, and particularly preferably methyl isocyanate acrylate, ethyl 2-isocyanate acrylate, or the oligomers thereof.

[0156] As the aforementioned reactive additives, commercially available products can be used directly, or they can be purified as needed. For example, Laromer (registered trademark) LR-9000 (manufactured by BASF) is a commercially available product.

[0157] When the polymerizable liquid crystal composition contains reactive additives, the content of reactive additives is typically 0.01 to 10 parts by mass, preferably 0.1 to 7 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

[0158] The polymeric liquid crystal compositions used to form liquid crystal curable films (x) can each be obtained by stirring the polymeric liquid crystal compound, solvent, polymerization initiator, and other components at a specified temperature.

[0159] The liquid crystal cured film (x) can be manufactured, for example, by a method including the following steps:

[0160] A process of forming a coating film of a polymeric liquid crystal composition comprising at least one polymeric liquid crystal compound on a substrate film or an alignment film described later, drying the coating film, and aligning the polymeric liquid crystal compound in the polymeric liquid crystal composition; and,

[0161] The process of polymerizing a polymerizable liquid crystal compound while maintaining its orientation to form a liquid crystal cured film.

[0162] A coating of a polymeric liquid crystal composition can be formed by coating a substrate film or an alignment film formed on a substrate film as described below.

[0163] Methods for coating polymeric liquid crystal compositions onto substrate films include known methods such as spin coating, extrusion coating, gravure coating, die coating, bar coating, applicator coating, and printing methods such as flexographic printing.

[0164] Next, the solvent is removed by drying or the like, thereby forming a dried coating film. Examples of drying methods include natural drying, ventilation drying, heating drying, and reduced pressure drying. At this time, by heating the coating film obtained from the polymeric liquid crystal composition, the solvent can be dried and removed from the coating film, and the polymeric liquid crystal compound can be oriented in a desired direction, such as a direction horizontal relative to the plane of the coating film. The heating temperature of the coating film can be appropriately determined considering the polymeric liquid crystal compound used and the material of the substrate film on which the coating film is formed. Generally, a temperature above the liquid crystal phase transition temperature is required to transform the polymeric liquid crystal compound into a liquid crystal phase state. To remove the solvent contained in the polymeric liquid crystal composition while simultaneously oriented the polymeric liquid crystal compound to the desired state, for example, the temperature can be heated to a level above the liquid crystal phase transition temperature (smectic phase transition temperature or nematic phase transition temperature) of the polymeric liquid crystal compound contained in the aforementioned polymeric liquid crystal composition. The heating temperature is preferably 3°C or more higher than the liquid crystal phase transition temperature of the polymeric liquid crystal compound, more preferably 5°C or more. There is no particular upper limit to the heating temperature, but to avoid damage to the coating, substrate film, etc. caused by heating, it is preferable to be below 180°C, and more preferably below 150°C.

[0165] It should be noted that the liquid crystal phase transition temperature can be measured using, for example, a polarizing microscope equipped with a temperature control stage, a differential scanning calorimeter (DSC), or a thermogravimetric differential calorimeter (TG-DTA). Furthermore, when two or more polymeric liquid crystal compounds are used in combination as polymeric liquid crystal compounds, the aforementioned phase transition temperature refers to the temperature measured using a mixture of polymeric liquid crystal compounds obtained by mixing all the polymeric liquid crystal compounds constituting the polymeric liquid crystal composition at the same ratio as the composition in the polymeric liquid crystal composition, as in the case of using a single polymeric liquid crystal compound. Additionally, it is known that the liquid crystal phase transition temperature of the polymeric liquid crystal compound typically present in the polymeric liquid crystal composition is lower than the liquid crystal phase transition temperature of the polymeric liquid crystal compound monomer.

[0166] The heating time can be appropriately determined according to the heating temperature, the type of polymeric liquid crystal compound used, the type of solvent, its boiling point and amount, etc., and is usually 0.5 to 10 minutes, preferably 0.5 to 5 minutes.

[0167] Solvent removal from the coating film can be performed simultaneously with heating the polymerizable liquid crystal compound above its liquid crystal phase transition temperature, or it can be performed separately. However, from the viewpoint of improving productivity, simultaneous removal is preferred. Before heating the polymerizable liquid crystal compound above its liquid crystal phase transition temperature, a pre-drying step can be provided to moderately remove the solvent from the coating film under conditions where the polymerizable liquid crystal compound contained in the coating film obtained from the polymerizable liquid crystal composition will not polymerize. Examples of drying methods in the pre-drying step include natural drying, ventilation drying, heating drying, and reduced pressure drying. The drying temperature (heating temperature) in this drying step can be appropriately determined according to the type of polymerizable liquid crystal compound used, the type of solvent, its boiling point, and its amount.

[0168] Next, in the obtained dried coating film, while maintaining the orientation state of the polymerizable liquid crystal compound, the polymerizable liquid crystal compound is polymerized by light irradiation, thereby forming a liquid crystal cured film as a polymer of the polymerizable liquid crystal compound existing in the desired orientation state. Photopolymerization is commonly used as the polymerization method. In photopolymerization, the light irradiating the dried coating film can be appropriately selected based on the type of photopolymerization initiator contained in the dried coating film, the type of polymerizable liquid crystal compound (especially the type of polymerizable groups possessed by the polymerizable liquid crystal compound), and their amount. Specific examples include light selected from one or more of the group consisting of visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays, and gamma rays, and active energy rays such as active electron rays. From the perspective of easy control of the polymerization reaction and the ability to use widely used devices in the art as photopolymerization devices, ultraviolet light is preferred. It is preferable to pre-select the type of polymerizable liquid crystal compound and photopolymerization initiator contained in the polymerizable liquid crystal composition in a manner that allows photopolymerization to be carried out using ultraviolet light. Furthermore, during polymerization, the drying coating can be cooled simultaneously using appropriate cooling methods while being irradiated with light, thereby controlling the polymerization temperature. By employing such cooling methods, when polymerizing the polymerizable liquid crystal compound at a lower temperature, a liquid crystal cured film can be appropriately formed even when using a substrate with low heat resistance. Additionally, the polymerization reaction can be promoted by increasing the polymerization temperature within a range that does not cause adverse effects due to heat during light irradiation (such as deformation of the substrate film due to heat). During photopolymerization, a patterned cured film can also be obtained through masking, development, and other processes.

[0169] Examples of light sources for the aforementioned active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380–440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

[0170] Ultraviolet radiation intensity is typically 10–3,000 mW / cm². 2 The intensity of ultraviolet irradiation is preferably within the wavelength range effective for activating the photopolymerization initiator. The irradiation time is typically 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds to 1 minute. When irradiated once or multiple times at this intensity, the cumulative light intensity is 10 to 3,000 mJ / cm². 2 Preferably, it is 50–2,000 mJ / cm². 2 More preferably 100–1,000 mJ / cm 2 .

[0171] The thickness of the liquid crystal cured film (x) is 0.5 μm to 3 μm, more preferably 1.0 μm or more, even more preferably 1.5 μm or more, and even more preferably 2.5 μm or less. When the thickness of the liquid crystal cured film (x) is within the above range, the desired optical properties are easily exhibited. Furthermore, strain at the bending point is easily suppressed during repeated bending. The thickness of the liquid crystal cured film (x) can be measured using an interferometer, laser microscope, or stylus-type thickness gauge.

[0172] A liquid crystal curable film (x) can be formed on an alignment film. An alignment film is a film with alignment control forces that orient a polymeric liquid crystal compound in a desired direction. By forming a liquid crystal curable film using a horizontal alignment film with alignment control forces that orient the polymeric liquid crystal compound in the horizontal direction and a vertical alignment film with alignment control forces that orient the polymeric liquid crystal compound in the vertical direction, the polymeric liquid crystal compound can be oriented in the desired direction with higher precision, resulting in a liquid crystal curable film that exhibits excellent optical properties when assembled into display devices, etc. The alignment control forces can be arbitrarily adjusted by the type of alignment film, surface condition, friction conditions, etc., and when the alignment film is formed from a photo-alignable polymer, they can be arbitrarily adjusted by polarized light irradiation conditions, etc.

[0173] As an alignment film, an alignment film is preferred that has solvent resistance, meaning it will not dissolve due to coating of the polymeric liquid crystal composition, and heat resistance for solvent removal and heat treatment during the alignment of the polymeric liquid crystal compound. Examples of alignment films include alignment films containing an alignment polymer, photoalignment films, grooved alignment films with raised or recessed patterns or multiple grooves on the surface, and stretched films stretched along the alignment direction. From the viewpoint of the accuracy and quality of the alignment angle, a photoalignment film is preferred.

[0174] Examples of oriented polymers include polyamides having intramolecular amide bonds, gelatin-like substances, polyimides having intramolecular imide bonds and their hydrolysates such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylates. Polyvinyl alcohol is preferred. Two or more oriented polymers can be used alone or in combination.

[0175] Orientation films containing orientation polymers are typically obtained by coating a composition (hereinafter also referred to as "orientation polymer composition") made by dissolving the orientation polymer in a solvent onto the surface of a substrate film or the like to which the orientation film is to be formed, and then removing the solvent, or by coating the orientation polymer composition onto a substrate, removing the solvent, and then rubbing (rubbing method). As a solvent, the same solvents exemplified above as solvents that can be used in polymerizable liquid crystal compositions can be cited.

[0176] The concentration of the oriented polymer in the oriented polymer composition is only required to be within the range where the oriented polymer material can be completely dissolved in the solvent. Relative to the solution, it is preferably 0.1 to 20% when converted to solid content, and more preferably about 0.1 to 10%.

[0177] Commercially available orientation film materials can also be used directly as orientation polymer compositions. Examples of commercially available orientation film materials include SUNEVER (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and OPTMER (registered trademark, manufactured by JSR Corporation).

[0178] As a method for coating an oriented polymer composition onto the surface of a substrate film or the like to which an oriented film is to be formed, the same method as that exemplified as a method for coating a polymeric liquid crystal composition onto a substrate film can be cited.

[0179] Methods for removing solvents contained in oriented polymer compositions include natural drying, ventilation drying, heating drying, and vacuum drying.

[0180] To impart orientation control force to an alignment film, a friction treatment (friction method) can be performed as needed. One method for imparting orientation control force using the friction method is to bring a film of an orientation polymer, formed on the surface of a substrate by coating an orientation polymer composition onto a substrate and then annealing it, into contact with a rotating friction roller wound with a friction cloth. If masking is performed during the friction treatment, multiple regions (patterns) with different orientation directions can also be formed on the alignment film.

[0181] Photoalignment films are typically obtained by coating a composition (hereinafter also referred to as "photoalignment film forming composition") comprising a polymer and / or monomer having photoreactive groups onto the surface of a substrate film to which the alignment film is to be formed, removing the solvent, and then irradiating it with polarized light (preferably polarized UV light). Photoalignment films are also advantageous in that the direction of the alignment control force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

[0182] A photoreactive group refers to a group that generates liquid crystal alignment ability through light irradiation. Specifically, it includes photoreactive groups that participate in molecular orientation induction or isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodecomposition reactions, which are the origin of liquid crystal alignment ability. Among these, groups that participate in dimerization reactions or photocrosslinking reactions are preferred from the perspective of excellent alignment. As a photoreactive group, it is preferred to have a group having unsaturated bonds, especially double bonds, and particularly preferred to have a group having at least one selected from the group consisting of carbon-carbon double bonds (C=C bond), carbon-nitrogen double bonds (C=N bond), nitrogen-nitrogen double bonds (N=N bond), and carbon-oxygen double bonds (C=O bond).

[0183] Examples of photoreactive groups with C=C bonds include vinyl, polyene, stilbazole, stilbazole group, chalcone, and cinnamoyl.

[0184] Examples of photoreactive groups with C=N bonds include those with aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups with N=N bonds include azophenyl, azonaphthyl, aromatic heterocyclic azo, diazo, formazanyl, and groups with an azobenzene oxide structure. Examples of photoreactive groups with C=O bonds include benzophenone, coumarin, anthraquinone, and maleimide. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

[0185] Preferably, the photoreactive groups involved in the photodimerization reaction are selected. Considering the need for less polarized light irradiation required for photoorientation and the ease of obtaining photoorientation films with excellent thermal and time stability, cinnamoyl and chalcone groups are preferred. Especially when the liquid crystal curing film is formed from a polymeric liquid crystal compound having (meth)acryloyloxy groups as polymerizable groups, using a polymer with cinnamoyl groups at the ends of its polymer side chains as the polymer with photoreactive groups to form the orientation film can improve the adhesion to the liquid crystal curing film.

[0186] As a solvent included in the composition for forming a photo-aligned film, the same solvents exemplified above as solvents that can be used in polymeric liquid crystal compositions can be appropriately selected based on the solubility of the polymer or monomer having photoreactive groups.

[0187] The content of the polymer or monomer with photoreactive groups in the composition for forming a photo-aligned film can be appropriately adjusted according to the type of polymer or monomer and the thickness of the target photo-aligned film. It is preferably set to at least 0.2% by mass, more preferably in the range of 0.3% to 10% by mass, relative to the mass of the composition for forming the photo-aligned film. The composition for forming the photo-aligned film may also contain polymers such as polyvinyl alcohol and polyimide, and photosensitizers, without significantly impairing the properties of the photo-aligned film.

[0188] As a method for coating a composition for forming a photo-alignment film onto the surface to which the alignment film is to be formed, the same method as the method for coating an orientation polymer composition can be cited. As a method for removing the solvent from the coated composition for forming a photo-alignment film, for example, natural drying, ventilation drying, heating drying, and vacuum drying can be cited.

[0189] To irradiate with polarized light, the product obtained by removing the solvent from the composition for forming a photo-alignment film coated on a substrate film can be directly irradiated with polarized UV light, or the polarized light can be irradiated from the substrate film side and allowed to pass through. Furthermore, it is particularly preferable that the polarized light is substantially parallel light. The wavelength of the polarized light used for irradiation should preferably be within the wavelength range where the photoreactive groups of the polymer or monomer having photoreactive groups can absorb light energy. Specifically, UV (ultraviolet) light in the wavelength range of 250–400 nm is particularly preferred. Examples of light sources used for this polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, KrF, ArF, and other ultraviolet lasers, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps being more preferred. Among these, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps, which emit ultraviolet light at a wavelength of 313 nm, have high luminous intensity and are therefore preferred. The light from the aforementioned light sources can be passed through a suitable polarizer for irradiation, thereby irradiating with polarized UV light. As the polarizer, polarizing filters, polarizing prisms such as Glan-Thomson and Glan-Taylor, and wire grid-type polarizers can be used.

[0190] It should be noted that if masking is applied during rubbing or polarized light irradiation, multiple regions (patterns) with different liquid crystal orientations can also be formed.

[0191] Groove-aligned films are films with raised or recessed patterns or multiple grooves (slots) on their surface. When a polymerizable liquid crystal compound is coated on a film having multiple linear grooves arranged at equal intervals, the liquid crystal molecules are aligned along the direction of the grooves.

[0192] Examples of methods for obtaining grooved alignment films include: exposing the surface of a photosensitive polyimide film through an exposure mask with a patterned slit, followed by development and rinsing to form a raised or recessed pattern; forming a layer of UV-curable resin before curing on a plate-shaped master with grooves on its surface, transferring the formed resin layer to a substrate or the like, and then curing it; and pressing a roll-shaped master with multiple grooves against a film of UV-curable resin before curing formed on the surface to which the alignment film is to be formed, forming a raised or recessed pattern, and then curing it.

[0193] The thickness of the alignment film (an alignment film containing an alignment polymer or a photo-alignment film) is typically in the range of 10 nm to 10,000 nm, preferably in the range of 10 nm to 2,500 nm, more preferably in the range of 10 nm to 1,000 nm, even more preferably in the range of 10 nm to 500 nm, and particularly preferably in the range of 50 nm to 250 nm.

[0194] (Polarizing film)

[0195] The polarizer constituting the optical laminate of the present invention is a film that has the function of extracting linearly polarized light from incident natural light, and is a polyvinyl alcohol-based resin film containing a dichroic pigment. As the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin film, a saponified form of a polyvinyl acetate-based resin can be used. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate as a homopolymer of vinyl acetate, copolymers of vinyl acetate with other monomers that can copolymerize therewith (e.g., ethylene-vinyl acetate copolymers, etc.) can also be mentioned.

[0196] Other monomers that can copolymerize with vinyl acetate include, for example, unsaturated carboxylic acids, alkenes, vinyl ethers, unsaturated sulfonic acids, and acrylamides with ammonium groups.

[0197] The degree of saponification of polyvinyl alcohol (PVA) resins is typically around 85–100 mol%, preferably 98 mol% or higher. PVA resins can be modified; for example, polyvinyl formal and polyvinyl acetal obtained by modification with aldehydes can also be used. The degree of polymerization of PVA resins is typically around 1,000–10,000, preferably in the range of 1,500–5,000.

[0198] The film obtained by forming a film from such a polyvinyl alcohol-based resin can be used as a preform for polarizing films. There are no particular limitations on the method for forming the polyvinyl alcohol-based resin film; known methods can be used. The film thickness of the polyvinyl alcohol preform can be set, for example, to approximately 10–150 μm.

[0199] Polarizing films are typically manufactured through the following steps: uniaxial stretching of a polyvinyl alcohol (PVA) resin film; dyeing the PVA resin film with a dichroic dye, thereby adsorbing the dichroic dye; treating the PVA resin film with the adsorbed dichroic dye using an aqueous boric acid solution; and washing with water after the boric acid-based aqueous solution treatment. It should be noted that by dyeing the PVA resin film with a dichroic dye, the dichroic dye is incorporated into the PVA resin film. When a polarizing film is manufactured using the above method, the polarizing film becomes a stretched PVA resin film containing the dichroic dye.

[0200] Uniaxial stretching of polyvinyl alcohol (PVA) resin films can be performed before, simultaneously with, or after dyeing with dichroic pigments. When uniaxial stretching is performed after dyeing, it can be performed before or during boric acid treatment. Uniaxial stretching can also be performed in multiple stages. During uniaxial stretching, stretching can be performed along the uniaxial axis between rollers with different circumferential speeds, or it can be performed using hot rollers. Furthermore, uniaxial stretching can be dry stretching performed in the atmosphere, or wet stretching performed using a solvent while the PVA resin film is swollen. From the viewpoint of suppressing polarizer deformation, the stretching ratio is preferably 8 times or less, more preferably 7.5 times or less, and even more preferably 7 times or less. Furthermore, from the viewpoint of performing the function of a polarizer, the stretching ratio is typically 4.5 times or more. By keeping the stretching ratio within the above range, the deformation of the polarizer over time can be suppressed.

[0201] One method for dyeing polyvinyl alcohol (PVA) resin films using dichroic pigments is to immerse the PVA resin film in an aqueous solution containing a dichroic pigment. Examples of dichroic pigments include iodine or dichroic dyes. Dichroic dyes include, for example, dichroic direct dyes formed from diazo compounds such as Direct Red 39, and dichroic direct dyes formed from triazo or tetraazo compounds. It should be noted that the PVA resin film is preferably pre-immersed in water before the dyeing process.

[0202] When using iodine as a dichroic pigment, the common method for staining is to impregnate a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide.

[0203] The iodine content in this aqueous solution is typically about 0.01 to 1 part by weight per 100 parts by weight of water. The potassium iodide content is typically about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for staining is typically about 20 to 40°C. The immersion time (staining time) in this aqueous solution is typically about 20 to 1,800 seconds.

[0204] It should be noted that before impregnating the polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide, the film can be immersed in water to facilitate swelling and dyeing. The impregnation temperature is typically 20–80°C, preferably 30–60°C, and the impregnation time (dyeing time) is typically 20–1800 seconds.

[0205] On the other hand, when using dichroic organic dyes as dichroic pigments, the dyeing method is usually adopted by impregnating a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye.

[0206] The content of dichroic organic dyes in this aqueous solution is typically 1 × 10⁻⁶ per 100 parts by weight of water. -4 Approximately 10 parts by weight, preferably 1×10 -3 ~1 part by weight, more preferably 1×10 -3 ~1×10 -2 Parts by weight. This aqueous solution may contain inorganic salts such as sodium sulfate as dyeing auxiliaries. The temperature of the dichroic dye aqueous solution used in dyeing is usually around 20–80°C. In addition, the immersion time (dyeing time) in this aqueous solution is usually around 10–1,800 seconds.

[0207] Boric acid treatment following dyeing with dichroic pigments is typically carried out by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The boric acid content in this aqueous solution is typically about 2 to 15 parts by weight per 100 parts by weight of water, preferably 5 to 12 parts by weight. When iodine is used as the dichroic pigment, the aqueous boric acid solution preferably contains potassium iodide, in which case the potassium iodide content is typically about 0.1 to 15 parts by weight per 100 parts by weight of water, preferably 5 to 12 parts by weight. The immersion time in the aqueous boric acid solution is typically about 60 to 1,200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. The temperature for boric acid treatment is typically above 50°C, preferably 50 to 85°C, more preferably 60 to 80°C.

[0208] Boric acid-treated polyvinyl alcohol (PVA) resin membranes are typically subjected to a water washing process. This washing can be performed, for example, by immersing the boric acid-treated PVA resin membrane in water. The water temperature during the washing process is usually around 5–40°C.

[0209] In addition, the soaking time is usually around 1 to 120 seconds.

[0210] After washing, a drying process is performed to obtain a polarizing film. The drying process can be carried out using, for example, a hot air dryer or a far-infrared heater. The drying temperature is typically around 30–100°C, preferably 50–80°C. The drying time is typically around 60–600 seconds, preferably 120–600 seconds. Through the drying process, the moisture content of the polarizing film is reduced to a practical level. Its moisture content is typically around 5–20% by mass, preferably 8–15% by mass. If the moisture content is within the above range, a polarizing film with moderate flexibility and excellent thermal stability can be obtained.

[0211] The polyvinyl alcohol-based resin film is obtained by uniaxial stretching, dyeing with dichroic pigments, boric acid treatment, washing, and drying as described above.

[0212] The thickness of the polarizer is preferably 5 to 40 μm, more preferably 5 to 20 μm.

[0213] (Transparent protective film)

[0214] The optical laminate of the present invention includes a transparent protective film bonded to the side of a polarizer opposite to the retardation film, separated by an adhesive layer. Polarizers are relatively thin and their surfaces are easily damaged. Therefore, it is common practice to have protective films on both sides of the polarizer to prevent external damage and contamination. However, in the optical laminate of the present invention, no protective film is laminated on the side of the polarizer facing the retardation film. This results in a thinner optical laminate with low oblique reflectivity.

[0215] In this invention, the transparent protective film has a total light transmittance of 90% or more, more preferably 92% or more. If the total light transmittance is above the aforementioned lower limit, an optical laminate with high transparency and excellent optical properties can be formed. The upper limit of the total light transmittance in the substrate film is not particularly limited, and it can be 100% or less. The total light transmittance can be measured, for example, according to JIS K 7361.

[0216] Furthermore, the 380nm transmittance of the aforementioned transparent protective film is 30% or less, preferably 25% or less, and more preferably 20% or less. If the 380nm transmittance of the transparent protective film is below the aforementioned upper limit, then when the optical laminate containing the transparent protective film is assembled into an image display device, the layers constituting the optical laminate (polarizer, liquid crystal curing film, etc.) can be protected from damage by ultraviolet light exposed on the viewing side. The lower limit of the 380nm transmittance of the transparent protective film is not particularly limited and can also be 0%. To ensure that the 380nm transmittance of the transparent protective film is 30% or less, the transparent protective film may contain ultraviolet absorbers, etc. The 380nm transmittance can be measured, for example, using a spectrophotometer.

[0217] As a transparent protective film bonded to a polarizer through an adhesive layer, any known resin film can be used as long as it meets the aforementioned requirements for total light transmittance and 380nm transmittance. Examples of resins suitable for forming transparent protective films include, for instance, polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate; polyacrylate; cellulose esters such as cellulose triacetate, cellulose diacetate, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; polyphenylene sulfide; and polyphenylene ether. Such resins can be used to form films using known methods such as solvent casting and melt extrusion. Surface treatments such as silicone treatment (e.g., mold release treatment), corona treatment, and plasma treatment can also be applied to the surface of the transparent protective film.

[0218] In one embodiment of the present invention, the transparent protective film preferably has a content of 100 g / m³. 2 / 24 hours or more, preferably 150g / m 2 / 24 hours or more, further preferably 200g / m 2 / 24 hours or more of moisture permeability. If the moisture permeability of the transparent protective film is above the lower limit mentioned above, then when using a dry-curing adhesive to laminate the retardation film and the polarizer to form an optical laminate, the solvent in the dry-curing adhesive can be efficiently removed not only from the substrate film constituting the retardation film but also from the transparent protective film. Therefore, an optical laminate can be obtained in which, when bent, the deformation in the liquid crystal cured film formed on the substrate film and the deformation of the optical laminate easily follow each other, and even under repeated bending, strain at the bending point is not easily induced. Furthermore, compared to the case where only the substrate film has high moisture permeability, the time for removing the solvent from the adhesive can be shortened, thus also being advantageous in terms of productivity. The upper limit of the moisture permeability of the transparent protective film is not particularly limited, but is typically 1000 g / m³. 2 / less than 24 hours, preferably 500g / m2 / less than 24 hours. The moisture permeability of the transparent protective film can be measured using the same method as that of the substrate film.

[0219] Using 100g / m 2 In the case of a transparent protective film that is more than 24 hours permeable to moisture, the transparent protective film and the substrate film can be the same or different.

[0220] The thickness of the transparent protective film can be appropriately determined according to the desired optical laminate composition. From the viewpoint of thinness, processability, flexibility and strength of the optical laminate, it is usually 5μm to 300μm, preferably 20μm to 200μm, and more preferably 20μm to 150μm.

[0221] The following is based on Figure 1 and Figure 2 An example of the layer configuration of the optical laminate of the present invention will be described, but the optical laminate of the present invention is not limited to these methods. Figure 1 The optical laminate 100 shown includes: a phase retardation film 1, a polarizer 3 laminated on one side of the aforementioned phase retardation film through an adhesive layer 2, and a transparent protective film 5 laminated on the side of the polarizer 3 opposite to the phase retardation film 1 through an adhesive layer 4. Figure 1 In the optical laminate 100 shown, the phase difference film 1 includes a liquid crystal curing film 13 formed on the substrate film 11 with the alignment film 12 in between.

[0222] The optical laminate of the present invention, in addition to comprising a retardation film, a polarizer, and a transparent protective film, and an adhesive layer for bonding them together, may also include other layers with various functions that can be assembled into an image display device, etc. However, in the layer configuration of retardation film / adhesive layer / polarizer / adhesive layer / transparent protective film formed adjacent to each other, no other layers are assembled. Examples of other layers include: for example, an adhesive layer for assembling the optical laminate into an image display device; for example, a second retardation film containing a liquid crystal compound oriented vertically relative to the film surface, which has optical properties different from the liquid crystal cured film (x), etc.

[0223] In this invention, the phase retardation film can be laminated with the polarizer on either side of the substrate film and the liquid crystal curing film constituting the phase retardation film, separated by an adhesive layer. For example, Figure 1 In the optical laminate 100 shown, the substrate film 11 constituting the retardation film 1 is laminated with the polarizer 3 through the adhesive layer 2. On the other hand, Figure 2 In the optical laminate 100 shown, the liquid crystal curing film 13 constituting the phase difference film 1 is laminated with the polarizer 3 through the adhesive layer 2.

[0224] When the optical laminate of the present invention is assembled into an image display device or the like, the heat resistance of the optical laminate is easily improved if the liquid crystal curing film (x) constituting the retardation film is not in contact with the adhesive layer used to bond the optical laminate to the components constituting the image display device, such as the image display unit. Therefore, in one embodiment of the present invention, it is preferable that the retardation film is in contact with the adhesive layer used to bond the retardation film to the polarizer on the side of the liquid crystal curing film constituting the retardation film.

[0225] The optical laminate of the present invention can be manufactured by bonding a retardation film, a polarizer, and a transparent protective film together using an adhesive. When using a dry-curing adhesive, the dry-curing adhesive can be applied / injected onto the bonding surfaces of the retardation film, the polarizer, and / or the transparent protective film to form a laminate of retardation film / adhesive layer / polarizer / adhesive layer / transparent protective film. After drying, the solvent in the adhesive is removed from the laminate, and the laminate is cured, thereby bonding the layers together.

[0226] The drying process and / or solvent removal can be carried out, for example, by blowing hot air. The temperature depends on the type of solvent, but is generally in the range of 30–200°C, preferably 35–150°C, more preferably 40–100°C, and even more preferably 50–100°C. The drying time is typically about 10 seconds to 30 minutes.

[0227] Alternatively, when using an active energy radiation-curable adhesive, the adhesive is cured by irradiating it with active energy radiation, thereby obtaining an adhesive layer. The source of the active energy radiation is not particularly limited, but is preferably active energy radiation with a luminescence distribution at a wavelength of 400 nm or less, and more preferably ultraviolet light. Specifically, examples of light sources include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black lamps, microwave-excited mercury lamps, and metal halide lamps.

[0228] The light irradiation intensity of the active energy X-ray curable adhesive can be appropriately determined according to the composition of the active energy X-ray curable adhesive, and there is no particular limitation. The effective wavelength range for activation of polymerization initiators is typically 10–3,000 mW / cm². 2 The irradiation time of the active energy ray-cured adhesive can be appropriately selected according to the active energy ray-cured adhesive being cured, and there is no particular limitation. It is typically 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiated once or multiple times at this ultraviolet irradiation intensity, the cumulative light intensity is typically 10 to 3,000 mJ / cm². 2 Preferably, it is 50–2,000 mJ / cm². 2More preferably 100–1,000 mJ / cm 2 .

[0229] The optical laminate of the present invention can be continuously manufactured by a roll-to-roll method. For example, it can be continuously manufactured by: producing a retardation film comprising a substrate film and a liquid crystal curing film (x) wound into a roll, conveying the retardation film while unwinding it, using an adhesive for bonding the layers, sequentially layering a separately fabricated polarizer and a transparent protective film on the retardation film, and then curing the adhesive by drying or photocuring.

[0230] Therefore, in one embodiment of the present invention, the optical laminate of the present invention can be in the form of an optical laminate roll wound into a roll shape.

[0231] The optical stack of the present invention, which includes a phase retardation film and a polarizer, can also be an elliptical polarizer. Therefore, the present invention includes an elliptical polarizer comprising the optical stack of the present invention.

[0232] In one embodiment of the present invention, it is preferred that the slow axis (optical axis) of the liquid crystal curing film constituting the optical laminate and the elliptical polarizer of the present invention forms an angle of 45±5° with the absorption axis of the polarizer.

[0233] The elliptical polarizing plate of the present invention can be used in various display devices.

[0234] A display device is a device that has display elements and includes light-emitting elements or devices as a light source. Examples of display devices include liquid crystal displays (LCDs), organic electroluminescent (EL) displays, inorganic electroluminescent (EL) displays, touch panel displays, electron emission displays (e.g., field emission displays (FEDs) and surface field emission displays (SEDs)), electronic paper (displays using electronic ink or electrophoretic elements), plasma displays, projection displays (e.g., grating light valve (GLV) displays and displays with digital micromirror devices (DMDs)), and piezoelectric ceramic displays. Liquid crystal displays include transmissive liquid crystal displays and semi-transmissive liquid crystal displays. This invention relates to any liquid crystal display device, including reflective liquid crystal display devices, direct-viewing liquid crystal display devices, and projection liquid crystal display devices. These display devices can be either two-dimensional or three-dimensional displays. Specifically, the elliptical polarizing plate of this invention is suitable for both organic and inorganic electroluminescent (EL) display devices, and the laminate of this invention is suitable for both liquid crystal display devices and touch panel display devices. These display devices, by incorporating the laminate of this invention which is less prone to interference unevenness, are able to exhibit excellent image display characteristics.

[0235] In one embodiment of the present invention, the above-mentioned display device is preferably a flexible image display device, and the present invention also includes a flexible image display device comprising the elliptical polarizing plate of the present invention.

[0236] The flexible image display device having the elliptical polarizing plate of the present invention preferably also has a window and a touch sensor.

[0237] A flexible image display device is formed, for example, of a flexible image display device laminate and an organic EL display panel. The flexible image display device laminate is positioned on the viewing side relative to the organic EL display panel and is configured in a bendable manner. In addition to the elliptical polarizing plate of the present invention described above, the flexible image display device laminate may also include a window, a touch sensor (for a touch panel), etc. Their stacking order is arbitrary, but it is preferable to stack them in the order of window, elliptical polarizing plate, and touch sensor, or in the order of window, touch sensor, and elliptical polarizing plate, starting from the viewing side.

[0238] If an elliptical polarizing plate is present on the viewing side of the touch sensor, the pattern of the touch sensor becomes less visually recognizable, and the visual recognizability of the displayed image improves, which is therefore preferred. The various components can be laminated using adhesives, bonding agents, etc. Furthermore, the laminate for the flexible image display device can have a light-shielding pattern formed on at least one side of any of the aforementioned layers: the viewing window, the elliptical polarizing plate, and the touch sensor.

[0239] The viewing window, positioned on the viewing side of the flexible image display device, serves to protect other components from external impacts or environmental changes such as temperature and humidity. Conventionally, glass has been used as such a protective layer; however, the viewing window in a flexible image display device is not as rigid and inflexible as glass, but rather possesses flexible properties. The aforementioned viewing window is formed from a flexible, transparent substrate and may include a hard coating on at least one side.

[0240] There are no particular limitations on the windows, touch sensors, etc., used as components of the laminated body for the flexible image display device; conventionally known windows, touch sensors, etc., can be used.

[0241] Example

[0242] The present invention will be described in more detail below through examples. It should be noted that, unless otherwise specified, "%" and "parts" in the examples refer to mass % and mass parts, respectively.

[0243] [Example 1]

[0244] (1) Preparation of composition for photo-alignment film formation

[0245] Two parts of polymer (1) with a number average molecular weight of 28,000 represented by the following chemical formula were mixed with 98 parts of o-xylene, and the mixture was stirred at 80°C for 1 hour to obtain a composition for photo-aligned film formation.

[0246] Polymer (1)

[0247] [Chemical Formula 3]

[0248]

[0249] [In the formula, Me represents a methyl group.]

[0250] (2) Preparation of polymeric liquid crystal composition for forming liquid crystal cured film

[0251] The following polymeric liquid crystal compounds were mixed: A-1 (86.0 parts), A-2 (14.0 parts), a polyacrylate compound (leveling agent / BYK-361N; manufactured by BYK-Chemie) (0.12 parts), 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1-one (photopolymerization initiator / Irgacure 369; manufactured by Ciba Specialty Chemicals Inc.) (3.0 parts), and LALOMER LR9000 (manufactured by BASF Japan Ltd.) (2.0 parts). Anisole was further added at a solid content concentration of 9%. A polymeric liquid crystal composition (A1) comprising polymeric liquid crystal compounds A-1 and A-2 was obtained.

[0252] It should be noted that the polymerizable liquid crystal compound A-1 was synthesized using the method described in Japanese Patent Application Publication No. 2010-31223. The maximum absorption wavelength λmax (LC) of the polymerizable liquid crystal compound A-1, measured in chloroform, is 350 nm.

[0253] Polymerizable liquid crystal compound A-1:

[0254] [Chemical Formula 4]

[0255]

[0256] Polymerizable liquid crystal compound A-2:

[0257] [Chemical Formula 5]

[0258]

[0259] (3) Fabrication of phase retardation film

[0260] A cellulose triacetate membrane (KC4CZ-TAC, 40 μm thick, manufactured by Kasuga Electric Co., Ltd.) was treated once using a corona treatment apparatus (AGF-B10; manufactured by Kasuga Electric Co., Ltd.) at an output power of 0.3 kW and a processing speed of 3 m / min. The aforementioned photo-alignment film forming composition was then coated onto the corona-treated surface using a bar coater, dried at 80°C for 1 minute, and irradiated with polarized UV light (SPOT CURE SP-7 with polarizer unit; manufactured by USHIO INC.) at 100 mJ / cm². 2 The cumulative light intensity was used to expose the film to polarized UV light to form an optical alignment film. The thickness of the obtained optical alignment film was measured using a polarized ellipticity meter (M-220, manufactured by Japan Spectrophotometer Co., Ltd.), and the result was 100 nm.

[0261] The moisture transmittance and total light transmittance of the aforementioned cellulose triacetate membrane (KC4CZ-TAC), used as the substrate membrane for the phase retardation membrane, were measured according to the following method.

[0262] (Measurement of moisture permeability)

[0263] The water permeability [g / (m²·24hr)] of the protective film at a temperature of 40°C and a relative humidity of 90% was determined using the cup method specified in JIS Z 0208. The water permeability of the above-mentioned TAC film was 370 g / m². 2 / 24 hours.

[0264] (Measurement of total light transmittance)

[0265] According to JIS K7361, the total light transmittance was measured using a haze meter HM150 manufactured by Murakami Color Technology Research Institute Co., Ltd. The total light transmittance of the above-mentioned TAC film was 93%.

[0266] In addition, the phase difference [Re(550) and Rth(550)] at a wavelength of 550 nm of the above-mentioned TAC film as a substrate was measured, and the result was approximately 0.

[0267] Next, the previously prepared polymeric liquid crystal composition (A1) containing a polymeric liquid crystal compound was coated onto the aforementioned photoalignment film using a rod coater and dried at 120°C for 1 minute. Then, ultraviolet light (cumulative light intensity at wavelength 313 nm: 500 mJ / cm² under nitrogen atmosphere) was irradiated from the side coated with the polymeric liquid crystal composition (A1) using a high-pressure mercury lamp (UniQure VB-15201BY-A; manufactured by USHIO INC.). 2This resulted in a phase retardation film, which is a laminate of a cellulose triacetate film (substrate film), a photoalignment film, and a liquid crystal curing film. The thickness of the obtained liquid crystal curing film was measured using a laser microscope (LEXT; manufactured by Olympus Corporation), and the result was 2.3 μm.

[0268] The phase difference at a wavelength of 550 nm was measured, and the result was Re(550) = 140 nm. Furthermore, the phase difference at wavelengths of 450 nm and 650 nm was measured, and the results were Re(450) / Re(550) = 0.85 and Re(650) / Re(550) = 1.05.

[0269] (4) Fabrication of polarizer (iodine PVA type polarizer)

[0270] A 30 μm thick polyvinyl alcohol (PVA: average degree of polymerization approximately 2400, degree of saponification ≥ 99.9 mol%) film was uniaxially stretched to approximately 5 times its original thickness using a dry stretching method. Further, while maintaining tension, it was immersed in pure water at 40°C for 40 seconds. Then, it was dyed by immersion in a dyeing aqueous solution with an iodine / potassium iodide / water mass ratio of 0.044 / 5.7 / 100 at 28°C for 30 seconds. Next, it was immersed in a boric acid aqueous solution with an iodide / boric acid / water mass ratio of 11.0 / 6.2 / 100 at 70°C for 120 seconds. Following this, it was washed with pure water at 8°C for 15 seconds, dried at 60°C for 50 seconds under a tension of 300 N, and then dried at 75°C for 20 seconds to obtain a 12 μm thick polarizer formed by the adsorption and orientation of iodine in the polyvinyl alcohol film.

[0271] (5) Fabrication of optical laminates

[0272] The phase retardation film and polarizer prepared above, as well as the triacetate cellulose film (TAC: Konica Minolta Opto Co., Ltd. "KC4UY") serving as a transparent protective film, are sequentially stacked. A water-based drying-curing adhesive is injected, with the triacetate side of the aforementioned phase retardation film and the polarizer, and the triacetate side of the aforementioned transparent protective film and the side of the polarizer opposite to the phase retardation film, in contact. The polarizer is bonded using clamping rollers with the absorption axis of the polarizer and the slow axis of the liquid crystal cured film in the phase retardation film at a 45° angle. While maintaining the tension of the resulting laminate at 430 N / m, it is dried at 60°C for 2 minutes to obtain an optical laminate I (elliptical polarizer) formed from the liquid crystal cured film / photoalignment film / substrate film / adhesive layer / polarizer / adhesive layer / transparent protective film.

[0273] It should be noted that the above-mentioned water-based drying and curing adhesive is prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (KURARAY POVAL KL318; manufactured by KURARAY Co., Ltd.) and 1.5 parts of water-soluble polyamide epoxy resin (Sumirez resin 650; manufactured by Sumika Chemtex Co., Ltd., an aqueous solution with a solid component concentration of 30%) to 100 parts of water.

[0274] The moisture transmittance and total light transmittance of the transparent protective film were measured using the same method as for the substrate film described above. The result was a moisture transmittance of 350 g / m². 2 The total light transmittance is 93% over 24 hours.

[0275] Furthermore, using a device consisting of a folder with a polarizer mounted on a spectrophotometer (Shimadzu UV-3150, manufactured by Shimadzu Corporation), the 380nm transmittance of the transparent protective film was measured by the double-beam method. This folder has a screen on the reference side that cuts off 50% of the light intensity. The 380nm transmittance of the transparent protective film was 8%.

[0276] (6) Evaluation of optical laminates

[0277] (i) Evaluation of flexibility

[0278] The flexural properties were evaluated using the general test method for coatings—flexural resistance (cylindrical mandrel method) described in JIS-K-5600-5-1, as follows.

[0279] Optical laminates were cut to squares of 25mm × 200mm. A Type II cylindrical mandrel bending resistance testing machine (manufactured by TP Giken Co., Ltd.) was used. Under conditions of 25°C and 55% RH, the liquid crystal cured layer of the phase retardation film was wound around a mandrel with a diameter of 6mm (bending radius R = 3mm) as the outer side, and a bending test was conducted. After the test, the optical laminates were visually inspected in a dark room using transmitted light to observe the crack formation. Cases where cracking was visually identifiable were marked "×", and cases where cracking was not visually identifiable were marked "○". The results are shown in Table 1.

[0280] (ii) Evaluation of oblique reflectivity

[0281] The oblique reflectivity of the optical laminate was measured as described below. A measurement sample was prepared by bonding the side of the optical laminate from the retardation film (in the case of optical laminate I, a liquid crystal curing film) to a reflector (a mirrored aluminum plate) using an acrylic adhesive.

[0282] A spectrophotometer (Konica Minolta Co., Ltd. CM3700A) was used to measure the oblique reflectance (reflectance Y value) of the sample by shining light from a D65 light source at an 8° angle. An oblique reflectance of 1% or more but less than 6% was recorded as ○, 6% or more but less than 8% as △, and 8% or more as ×. The results are shown in Table 1.

[0283] (iii) Evaluation of heat resistance test

[0284] An acrylic adhesive is used to bond the side of the optical laminate from the phase retardation film to a glass plate to prepare the measurement sample.

[0285] The obtained test samples were placed in an oven at 85°C for 500 hours. The in-plane phase difference was then measured using a KOBRA-WR instrument manufactured by Oji Measurement Instrument Co., Ltd., to determine the change in the in-plane phase difference at 550 nm before and after the heat resistance test. A change of 1 nm or more but less than 3 nm was recorded as ○, a change of 3 nm or more but less than 5 nm was recorded as △, and a change of 5 nm or more was recorded as ×. The results are shown in Table 1.

[0286] [Example 2]

[0287] When bonding the retardation film to the polarizer, the liquid crystal curing film side is bonded to the polarizer. Otherwise, the same procedure as in Example 1 is followed to manufacture an optical laminate consisting of a substrate film / photoalignment film / liquid crystal curing film / adhesive layer / polarizer / adhesive layer / transparent protective film, and the results are evaluated. The results are shown in Table 1.

[0288] [Example 3]

[0289] As a transparent protective film, a polymethyl methacrylate resin film (manufactured by Sumitomo Chemical Co., Ltd., moisture permeability: 50g / m³) is used. 2 (24-hour total light transmittance: 93%, 380nm transmittance: 6%), otherwise, the same procedure as in Example 1 was followed to manufacture an optical laminate formed of a substrate film / photoalignment film / liquid crystal curing film / adhesive layer / polarizer / adhesive layer / transparent protective film, and the laminate was evaluated.

[0290] The results are shown in Table 1.

[0291] [Example 4]

[0292] As a transparent protective film, a cyclic olefin polymer film (COP; ZF-14; manufactured by ZEON Corporation, Japan) with added ultraviolet absorbers is used; moisture permeability: 13 g / m³. 2(24-hour total light transmittance: 92%, 380nm transmittance: 8%). Otherwise, the optical laminate consisting of a substrate film / photoalignment film / liquid crystal curing film / adhesive layer / polarizer / adhesive layer / transparent protective film was manufactured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0293] [Comparative Example 1]

[0294] As the substrate film, the TAC film used as the transparent protective film in Example 1 was employed. In the optical laminate fabrication process, after bonding the transparent protective film to the polarizer using the same water-based, dry-curing adhesive as used in Example 1, an acrylic adhesive with a cured thickness of 5 μm was used to bond the side of the polarizer without the transparent protective film to the liquid crystal cured film side of the retardation film. The triacetic acid cellulose film, serving as the substrate film, was then peeled off. Otherwise, the process was the same as in Example 1 to fabricate an optical laminate consisting of a photo-alignment film / liquid crystal cured film / adhesive layer / polarizer / adhesive layer / transparent protective film, and the results were evaluated. The results are shown in Table 1.

[0295] [Comparative Example 2]

[0296] Without peeling off the triacetic acid cellulose used as the substrate film, an optical laminate consisting of a substrate film / photoalignment film / liquid crystal curing film / adhesive layer / polarizer / adhesive layer / transparent protective film was manufactured in the same manner as in Comparative Example 1, and evaluated. The results are shown in Table 1.

[0297] [Reference Example 1]

[0298] As the substrate membrane, a cyclic olefin polymer membrane (COP; ZF-14; manufactured by ZEON Corporation, Japan, moisture permeability: 13 g / m³) is used. 2 (24-hour total light transmittance: 92%, 380nm transmittance: 90%). Otherwise, the optical laminate consisting of a substrate film / photoalignment film / liquid crystal curing film / adhesive layer / polarizer / adhesive layer / transparent protective film was manufactured and evaluated in the same manner as in Example 4. The results are shown in Table 1.

[0299] [Table 1]

[0300]

[0301] It was confirmed that the optical laminates (Examples 1-4) having the layer structure according to the present invention have excellent flexibility and low oblique reflectivity.

[0302] Explanation of reference numerals in the attached figures

[0303] 1: Phase retardation film

[0304] 2: Adhesive layer

[0305] 3: Polarizing film

[0306] 4: Adhesive layer

[0307] 5: Transparent protective film

[0308] 11: Substrate film

[0309] 12: Orientation film

[0310] 13: Liquid crystal curing film

[0311] 100: Optical laminate

Claims

1. An optical laminate, which is an optical laminate comprising sequentially a retardation film, a polarizer, and a transparent protective film. The phase retardation film contains 100 g / m 2 A substrate film with a moisture permeability of 24 hours or more, and a liquid crystal curing film formed on the substrate film, wherein the thickness of the liquid crystal curing film is 0.5 μm or more and 3 μm or less, and satisfies the following formulas (1) and (2) in a single layer: Re(450) / Re(550)≤1.00 (1) 1.00≤Re(650) / Re(550) (2) In the formula, Re(λ) represents the in-plane phase difference at wavelength λ. The polarizer is composed of a polyvinyl alcohol-based resin film containing dichroic pigments. The transparent protective film has a total light transmittance of over 90% and a 380nm transmittance of less than 30%. The phase retardation film, the polarizer, and the transparent protective film are adjacent to each other, separated by an adhesive layer. The phase retardation film is in contact with the adhesive layer that bonds the phase retardation film and the polarizer on the side of the liquid crystal curing film. The thickness of the adhesive layer is more than 10 nm and less than 5 μm. The adhesive layer is formed from an adhesive selected from dry-curing adhesives and chemically reactive adhesives.

2. The optical laminate as claimed in claim 1, wherein, The substrate film has a total light transmittance of over 90%, and the absolute value of the phase difference Rth(550) in the thickness direction for 550nm light is less than 5nm.

3. The optical laminate as described in claim 1 or 2, wherein, The phase retardation film has a photo-alignment film with a thickness of more than 10 nm and less than 1000 nm between the substrate film and the liquid crystal curing film.

4. The optical laminate as described in claim 1 or 2, wherein, The liquid crystal curable film is obtained by curing at least one compound that has at least one maximum absorption in the wavelength range of 300-400 nm.

5. The optical laminate as described in claim 1 or 2, wherein, The liquid crystal curing film satisfies the following formula (3): 100nm≤Re(550)≤170nm (3) In the formula, Re(λ) represents the in-plane phase difference at wavelength λ.

6. The optical laminate as described in claim 1 or 2, wherein, The transparent protective film has a density of 100g / m³. 2 / 24 hours or more of moisture permeability.

7. The optical laminate as described in claim 1 or 2, wherein, The adhesive layer is formed by a dry-curing adhesive.

8. The optical laminate as claimed in claim 7, wherein, The drying-curing adhesive contains polyvinyl alcohol.

9. An optical laminate roll, which is formed by winding the optical laminate according to any one of claims 1 to 8.

10. An elliptical polarizing plate comprising the optical laminate of any one of claims 1 to 8.

11. An organic EL display device comprising the elliptical polarizing plate of claim 10.

12. A flexible image display device comprising the elliptical polarizing plate of claim 10.

13. The flexible image display device of claim 12, further comprising a viewing window and a touch sensor.

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