Polarizing plate and circular polarizing plate including same

Abstract

The present invention addresses the problem of providing: a polarizing plate having excellent light resistance; and a circular polarizing plate including the polarizing plate. The polarizing plate comprises, in order from the observation side, a resin layer, a bonding layer a, a horizontal polarizing film, and a protective layer, the horizontal polarizing film being adjacent to the protective layer, comprising a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, and having a thickness of 0.1-5 [mu] m. The protective layer is a layer of a cured product of a curable composition containing a polymerizable compound, and a laminate of the polarizing plate comprising a layer closer to the observation side than the horizontal polarizing film has a transmittance of 10% or less at a wavelength of 380 nm, a transmittance of 20% or less at a wavelength of 400 nm, and a transmittance of 80% or more at a wavelength of 450 nm.

Description

Technical Field

[0001] The present invention relates to a polarizing plate and a circular polarizing plate comprising the above-described polarizing plate. Background Technology

[0002] Previously, polarizing plates were used in various image display panels, such as liquid crystal display panels and organic electroluminescent (OLED) display panels, to be bonded to liquid crystal cells and OLED display elements. In recent years, there has been a continuous demand for thinner displays, including image display panels, and this has led to further demands for thinner polarizing plates, which are one of their constituent elements. To address these demands, thin host-guest type polarizing plates containing polymerizable liquid crystal compounds and dichroic compounds have been proposed, for example. For instance, Patent Document 1 discloses a laminate containing a polarizing plate with a linear polarizing layer and an adhesive layer, and a protective film on one or both sides of the linear polarizing layer; Patent Document 2 discloses a polarizing film having resin layers on both sides of the polarizing plate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-062652

[0006] Patent Document 2: Japanese Patent Application Publication No. 2020-56834 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In the case of using a composition comprising a polymeric liquid crystal compound and a dichroic pigment to form a polarizing film for the purpose of thinning, it is known that the lightfastness of conventional laminates is insufficient, especially with the deterioration of the dichroic pigment, sometimes resulting in a decrease in polarization performance. Therefore, the objective of the present invention is to provide a polarizing plate with excellent lightfastness and a circular polarizing plate comprising the polarizing plate.

[0009] Methods for solving problems

[0010] The inventors conducted in-depth research to solve the aforementioned problems. As a result, they discovered that by adjusting the optical properties of a laminate composed of layers positioned closer to the observation side than the horizontal polarizing film to a specified range, the aforementioned problems could be solved, thus completing this invention.

[0011] That is, the present invention includes the following suitable methods.

[0012] [1] A polarizing plate, comprising, from the observation side, a resin layer, an adhesive layer a, a horizontal polarizing film, and a protective layer in sequence.

[0013] The aforementioned horizontal polarizing film, adjacent to the aforementioned protective layer, is composed of a cured product comprising a polymeric liquid crystal composition containing a polymeric liquid crystal compound and a dichroic pigment, and has a thickness of 0.1 to 5 μm.

[0014] The aforementioned protective layer is a cured layer of a curable composition containing a polymeric compound.

[0015] The aforementioned polarizing plate, consisting of a layer closer to the observation side than the horizontal polarizing film, has a transmittance of less than 10% at a wavelength of 380 nm, less than 20% at a wavelength of 400 nm, and more than 80% at a wavelength of 450 nm.

[0016] [2] According to the polarizing plate described in [1], on the opposite side of the surface of the horizontal polarizing film adjacent to the protective layer, there is a cured resin layer, with or without an alignment layer.

[0017] [3] According to the polarizing plate described in [2], wherein the above-mentioned cured resin layer is a cured layer of a curable composition containing a polyfunctional (meth)acrylate and has a thickness of 0.1 to 5 μm.

[0018] [4] The polarizing plate described in any one of [1] to [3], wherein the transmittance of the laminate of the polarizing plate, which is composed of a layer closer to the observation side than the horizontal polarizing film, is less than 5% at a wavelength of 300 nm.

[0019] [5] The polarizing plate according to any one of [1] to [4], wherein the transmittance of the resin layer is less than 5% at a wavelength of 300 nm, less than 10% at a wavelength of 380 nm, less than 20% at a wavelength of 400 nm, and more than 80% at a wavelength of 450 nm.

[0020] [6] The polarizing plate described in any one of [1] to [5], wherein the average transmittance of the laminate of the polarizing plate, which is composed of a layer closer to the observation side than the horizontal polarizing film, is less than 30% at a wavelength of 400 to 420 nm.

[0021] [7] The polarizing plate described in any one of [1] to [6], wherein the dichroic pigments include pigments that have absorption at wavelengths below 450 nm.

[0022] [8] The polarizing plate according to any one of [1] to [7], wherein the protective layer is a cured layer of a curable composition containing a cationic polymeric compound.

[0023] [9] A circular polarizing plate, which is a circular polarizing plate formed by stacking a polarizing plate and a phase difference film as described in any one of [1] to [8] with an adhesive layer b sandwiched between them, wherein the protective layer, the adhesive layer b and the phase difference film contained in the polarizing plate are sequentially adjacent to each other.

[0024]

[10] According to the circular polarizer described in [9], wherein the phase difference film is composed of a cured product containing a curable composition of a polymeric liquid crystal compound.

[0025] Invention Effects

[0026] According to the present invention, it is possible to provide a polarizing plate with high light resistance and a circular polarizing plate comprising the polarizing plate. Detailed Implementation

[0027] 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.

[0028] <Polarizing plate>

[0029] The polarizing plate of the present invention comprises, from the observation side, a resin layer, an adhesive layer a, a horizontal polarizing film, and a protective layer in sequence.

[0030] The aforementioned horizontal polarizing film, adjacent to the aforementioned protective layer, is composed of a cured polymeric liquid crystal composition containing a polymeric liquid crystal compound and a dichroic pigment, and has a thickness of 0.1 to 5 μm.

[0031] The aforementioned protective layer is a cured layer of a curable composition containing a polymeric compound.

[0032] The aforementioned polarizing plate, consisting of a layer closer to the observation side than the horizontal polarizing film, has a transmittance of less than 10% at a wavelength of 380 nm, less than 20% at a wavelength of 400 nm, and more than 80% at a wavelength of 450 nm.

[0033] In the polarizing plate of the present invention, the laminate composed of layers further to the observation side than the horizontal polarizing film has a transmittance of less than 10% at a wavelength of 380 nm, less than 20% at a wavelength of 400 nm, and more than 80% at a wavelength of 450 nm. Surprisingly, by adjusting the transmittance of the laminate composed of layers further to the observation side than the horizontal polarizing film at specific wavelengths to the above range, it is known that a polarizing plate and a circular polarizing plate comprising the polarizing plate can be provided. This polarizing plate maintains good visibility and, for polarizing plates comprising a horizontal polarizing film containing a cured polymeric liquid crystal composition, exhibits high lightfastness and time-stable polarization characteristics. The polymeric liquid crystal composition contains a dichroic pigment.

[0034] In the polarizing plate of the present invention, the laminate composed of layers closer to the observation side than the horizontal polarizing film has a transmittance of 10% or less at a wavelength of 380 nm. It is known that when the transmittance exceeds 10%, the decomposition of dichroic pigments contained in the horizontal polarizing film is sometimes insufficiently suppressed, resulting in a decrease in polarization. From the viewpoint of the lightfastness of the polarizing plate, the transmittance of this laminate at a wavelength of 380 nm is preferably 5% or less, more preferably 1% or less, and even more preferably 0.5% or less.

[0035] In the polarizing plate of the present invention, the laminate composed of layers closer to the observation side than the horizontal polarizing film has a transmittance of 20% or less at a wavelength of 400 nm. It is known that when the transmittance exceeds 20%, the decomposition of dichroic pigments contained in the horizontal polarizing film is sometimes insufficiently suppressed, resulting in a decrease in polarization. From the viewpoint of the lightfastness of the polarizing plate, the transmittance of this laminate at a wavelength of 400 nm is preferably 10% or less, more preferably 5% or less, and even more preferably 4% or less.

[0036] In the polarizing plate of the present invention, the laminate composed of layers further to the observation side than the horizontal polarizing film has a transmittance of 80% or more at a wavelength of 450 nm. When this transmittance is less than 80%, the visibility of the polarizing plate decreases. From the viewpoint of display function when the polarizing plate and the display device are used in combination, the transmittance of this laminate at a wavelength of 450 nm is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more.

[0037] There are no particular limitations on the method for adjusting the transmittance of a laminate consisting of layers closer to the observation side than the horizontal polarizing film to the aforementioned range. It is possible to consider providing a layer with ultraviolet absorption capability in the layer closer to the observation side than the horizontal polarizing film. For example, as described later, it is possible to impart ultraviolet absorption capability to the resin layer and / or the adhesive layer a.

[0038] The polarizing plate of the present invention comprises, from the observation side, a resin layer, an adhesive layer a, a horizontal polarizing film, and a protective layer in sequence. A laminate composed of layers further from the observation side than the horizontal polarizing film includes at least a resin layer and an adhesive layer a, and may also include other layers of the polarizing plate of the present invention disposed further from the observation side than the horizontal polarizing film. Regarding the above-mentioned transmittance measurement, an ultraviolet-visible-near-infrared (UV-Vis-NIR) spectrophotometer can be used, with the laminate composed of layers further from the observation side than the horizontal polarizing film as the test sample. This laminate can be obtained by peeling the laminate at the interface on the surface of the adhesive layer a side of the horizontal polarizing film in the polarizing plate, or it can be obtained by laminating only the layers further from the observation side than the horizontal polarizing film. When the horizontal polarizing film includes an alignment layer, and this alignment layer is laminated further from the observation side than the horizontal polarizing film, the alignment layer is included in the layers further from the observation side than the horizontal polarizing film. Conversely, when the horizontal polarizing film is further from the observation side than this alignment layer, the alignment layer is not included in the layers further from the observation side than the horizontal polarizing film.

[0039] In a preferred embodiment of the present invention, from the viewpoint of the light resistance of the polarizing plate, the transmittance of the laminate consisting of layers that are closer to the observation side than the horizontal polarizing film at a wavelength of 300 nm is preferably 5% or less, more preferably 1% or less, further preferably 0.8% or less, and particularly preferably 0.5% or less.

[0040] In a preferred embodiment of the present invention, from the viewpoint of balancing the lightfastness of the polarizing plate and the display function when the polarizing plate and the display device are used together, the transmittance (T0) of the laminate composed of layers closer to the observation side than the horizontal polarizing film at a wavelength of 450 nm is considered. 450 ) relative to the transmittance at a wavelength of 400 nm (T 400 The ratio of (T) 450 / T 400 The concentration is preferably 20 or more, more preferably 40 or more, and even more preferably 50 or more.

[0041] In this invention, from the viewpoint of suppressing the photo-oxidative degradation of dichroic pigments contained in the horizontal polarizing film, the transmittance of the laminate composed of layers closer to the observation side than the horizontal polarizing film in the wavelength range of 400-420 nm is important. Therefore, in a preferred embodiment of the invention, from the viewpoint of the lightfastness of the polarizing plate, the average transmittance of the laminate composed of layers closer to the observation side than the horizontal polarizing film in the wavelength range of 400-420 nm is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. The average transmittance referred to here is the value obtained by summing the transmittance of each wavelength in the 400-420 nm range and dividing it by the number of wavelengths, which in this case is 21; it is the value obtained by averaging the integral value (area) of the transmission spectrum in the 400-420 nm range. When this value is within the above-mentioned range, the photo-oxidative degradation of dichroic pigments contained in the horizontal polarizing film can be particularly suppressed.

[0042] In a further preferred embodiment of the present invention, from the viewpoint of the light resistance of the polarizing plate, it is even more preferable that the laminate composed of a layer closer to the observation side than the horizontal polarizing film has a transmittance of 5% or less at a wavelength of 300 nm, a transmittance of 10% or less at a wavelength of 380 nm, a transmittance of 20% or less at a wavelength of 400 nm, and a transmittance of 80% or more at a wavelength of 450 nm.

[0043] (Horizontal polarizing film)

[0044] In the polarizing plate of the present invention, the horizontal polarizing film (hereinafter also referred to as "polarizing film") is composed of a cured polymeric liquid crystal composition (hereinafter also referred to as "polarizing film forming composition") containing a polymeric liquid crystal compound and a dichroic pigment, and has a thickness of 0.1 to 5 μm. This polarizing film can be a single layer or a multilayer comprising two or more layers of the cured polymeric liquid crystal composition, or it can be a multilayer comprising one or more layers of the cured polymeric liquid crystal composition and one or more alignment films for forming that layer. The horizontal polarizing film is a polarizing film formed by curing the polymeric liquid crystal compound and the dichroic pigment in a state where they are aligned horizontally relative to the plane of the polarizing film. The horizontal polarizing film generally functions to allow light vibrating in the transmission axis direction to pass through, but blocks polarized light with vibration components perpendicular to it, thus functioning as a polarizing film that extracts linearly polarized light from incident natural light.

[0045] In a preferred embodiment of the invention, from the viewpoint of suppressing curling, the polarizing film is preferably a single layer comprising a cured polymeric liquid crystal composition and the layer comprising the cured polymeric liquid crystal composition is adjacent to the protective layer; or the polarizing film comprises a layer comprising a cured polymeric liquid crystal composition and an alignment film for forming the layer, the layer comprising the cured polymeric liquid crystal composition being adjacent to the protective layer.

[0046] The thickness of the polarizing film is 0.1–5 μm. The thickness of the polarizing film refers to the thickness of the polarizing layer comprising the cured polymeric liquid crystal composition contained in the polarizing film. In the case where the polarizing film has an alignment film, the thickness of the alignment film is not included in the thickness of the polarizing film. From the viewpoint of further thinning and suppressing curling, the thickness of the polarizing film is preferably 0.5–4 μm, more preferably 1–3.5 μm, and even more preferably 1.5–3 μm. The thickness of the polarizing film can be measured using a laser microscope, a film thickness gauge, an ellipsometer, etc. The same method applies to measuring the thickness of each layer constituting the polarizing plate and the protective layer of the circular polarizing plate.

[0047] A polarization film forming composition for forming a polarization film will be described. The polymerizable liquid crystal compound contained in the polarization film forming composition is a compound having at least one polymerizable group and exhibiting liquid crystal properties. Here, a polymerizable group refers to a group that participates in a polymerization reaction, preferably a photopolymerizable group. A photopolymerizable group refers to a group that can participate in a polymerization reaction through an active free radical generated by a polymerization initiator or an acid, etc. Examples of polymerizable groups in a polymerizable liquid crystal compound include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, ethylene oxide, and oxetyl. Among these, a free radical polymerizable group is preferred, acryloyloxy, methacryloyloxy, vinyloxy, ethylene oxide, and oxetyl are more preferred, and acryloyloxy or methacryloyloxy is even more preferred.

[0048] In this invention, the polymerizable liquid crystal compound is preferably a liquid crystal compound exhibiting a smectic liquid crystal phase. By using a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase, a polarizing film with high orientation order and excellent polarization function can be formed. From the viewpoint of achieving higher orientation order, the liquid crystal state exhibited by the polymerizable liquid crystal compound is more preferably a higher-order smectic phase (higher-order smectic liquid crystal state). Here, higher-order smectic phase refers to smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase, and smectic L phase, among which smectic B phase, smectic F phase, and smectic I phase are more preferred, and smectic B phase is even more preferred. The liquid crystal property can be thermotropic liquid crystal or lyotropic liquid crystal; from the viewpoint of being able to achieve dense film thickness control, thermotropic liquid crystal is preferred. In addition, the polymerizable liquid crystal compound can be a monomer, an oligomer formed by polymerization of polymeric groups, or a polymer.

[0049] Examples of such polymeric liquid crystal compounds include compounds represented by formula (A) (hereinafter also referred to as "polymeric liquid crystal compound (A)").

[0050] U 1 -V 1 -W 1 -(X) 1 -Y 1 ) n -X 2 -W 2 -V 2 -U 2 (A)

[0051] In formula (A),

[0052] X 1 and X 2 Each of these groups independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom in the divalent aromatic group or divalent alicyclic hydrocarbon group can be substituted by a substituent selected from halogen atoms, alkyl groups with 1 to 4 carbon atoms, fluoroalkyl groups with 1 to 4 carbon atoms, alkoxy groups with 1 to 4 carbon atoms, cyano groups, and nitro groups. The carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group can be substituted by oxygen atoms, sulfur atoms, or nitrogen atoms. Wherein, X 1 and X 2 At least one of them is 1,4-phenylene, which may have the above-mentioned substituents, or cyclohexane-1,4-diyl, which may have the above-mentioned substituents.

[0053] Y 1 It is a single bond or a divalent linker.

[0054] When n is 1 to 3, and n is 2 or more, there are multiple X's. 1They can be the same or different. X 2 Can be used with multiple X 1 Any one or all of them can be the same, or they can be different. Furthermore, when n is 2 or more, multiple Ys... 1 They can be the same or different. From the viewpoint of liquid crystal properties, n is preferably 2 or more.

[0055] U 1 It represents a hydrogen atom or a polymeric group.

[0056] U 2 It indicates a polymerizable group.

[0057] W 1 and W 2 Each is an independent single bond or a divalent linker.

[0058] V 1 and V 2 Each can independently represent an alkyldiyl group with 1 to 20 carbon atoms that can have substituents, wherein the -CH2- group constituting the alkyldiyl group can be replaced by -O-, -CO-, -S- or -NH-.

[0059] In polymeric liquid crystal compound (A), X 1 and X 2 Each is preferably 1,4-phenylene, which may have substituents, or cyclohexane-1,4-diyl, which may have substituents, X 1 and X 2 At least one of them is a 1,4-phenylene that may have a substituent, or a cyclohexane-1,4-diyl that may have a substituent, preferably trans-cyclohexane-1,4-diyl. Examples of substituents that may be present in the 1,4-phenylene or the cyclohexane-1,4-diyl that may have a substituent include alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, and butyl, cyano groups, and halogen atoms such as chlorine and fluorine atoms. Unsubstituted is preferred.

[0060] Furthermore, from the viewpoint of the manifestation of smectic liquid crystal properties, the polymeric liquid crystal compound (A) preferably has an asymmetric structure in the part represented by formula (A1) in formula (A) (hereinafter referred to as "partial structure (A1)").

[0061] -(X) 1 -Y 1 ) n -X 2 - (A1)

[0062] [In the formula, X] 1 Y 1 X 2 [and n] have the same meaning as above.

[0063] As a polymeric liquid crystal compound (A) with a partially asymmetric structure (A1), examples include n=1 and 1 X. 1 With X 2 A consists of polymeric liquid crystal compounds with different structures from each other.

[0064] Additionally, examples of n being 2 and having 2 Ys can be given. 1 They have the same structure and two X's 1 For the same structure and 1 X 2 To be with these two X 1 Polymerizable liquid crystal compounds with different structures (A);

[0065] 2 X 1 In and W 1 bonded X 1 For another X 1 and X 2 Different structures, and another X 1 With X 2 A is a polymeric liquid crystal compound with the same structure as each other.

[0066] In addition, examples of n being 3 and having 3 Ys can be given. 1 They have the same structure and 3 X's 1 And 1 X 2 A polymeric liquid crystal compound (A) with a structure that is completely different from the other three.

[0067] Y 1 Preferred bonds include -CH2CH2-, -CH2O-, -CH2CH2O-, -COO-, -OCOO-, single bonds, -N=N-, and -CR. a =CR b -、-C≡C-、-CR a =N- or -CO-NR a -. R a and R b Each can independently represent an alkyl group having 1 to 4 hydrogen atoms or carbon atoms. Y 1 More preferably, it is -CH2CH2-, -COO-, or a single bond, in the presence of multiple Y 1 In the case of X 2 Bonded Y 1 More preferably, it is -CH2CH2- or -CH2O-. In X 1 and X 2 When all of them have the same structure, it is preferable to have two or more Y atoms with different bonding methods. 1 In the existence of multiple Ys as different bonding methods 1In such cases, it becomes an asymmetric structure, and therefore tends to exhibit smectic liquid crystal properties.

[0068] U 2 It is a polymerizable group. U 1 It is a hydrogen atom or a polymeric group, preferably a polymeric group. U is preferred. 1 and U 2 All are polymerizable groups, preferably free radical polymerizable groups. Examples of polymerizable groups include those previously exemplified as polymerizable groups present in the polymerizable liquid crystal compound (A). U 1 The polymeric groups shown are related to U 2 The polymerizable groups shown may be different from each other, but are preferably of the same kind. In addition, the polymerizable groups may be in a polymerized state or an unpolymerized state, but are preferably in an unpolymerized state.

[0069] As V 1 and V 2 Examples of alkyldiyl groups shown include methylene, ethylene, propane-1,3-diyl, butane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, decane-1,10-diyl, tetradecane-1,14-diyl, and eicosane-1,20-diyl. 1 and V 2 Preferably, it is an alkyldiyl group with 2 to 12 carbon atoms, and more preferably an alkyldiyl group with 6 to 12 carbon atoms.

[0070] Examples of substituents that may be present in the alkyl diester include cyano groups and halogen atoms. The alkyl diester is preferably unsubstituted, and more preferably an unsubstituted straight-chain alkyl diester.

[0071] W 1 and W 2 The components are preferably single bonds, -O-, -S-, -COO-, or -OCOO-, and more preferably single bonds or -O-.

[0072] As a structure that readily exhibits smectic liquid crystal properties, a molecular structure with asymmetry in its molecular structure is preferred. Specifically, polymeric liquid crystal compounds having structures shown in formulas (Aa) to (Ai) readily exhibit smectic liquid crystal properties and are suitable as polymeric liquid crystal compounds (A). Furthermore, from the viewpoint of readily exhibiting higher-order smectic liquid crystal properties, structures having formulas (Aa), (Ab), or (Ac) are more preferred. It should be noted that in formulas (Aa) to (Ai), Indicates a connection key (single key).

[0073] [Chemical Formula 1]

[0074]

[0075] As a polymerizable liquid crystal compound (A), specifically, compounds represented by formulas (A-1) to (A-25) can be cited as examples. When the polymerizable liquid crystal compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably the trans form.

[0076] [Chemical Formula 2]

[0077]

[0078] [Chemical Formula 3]

[0079]

[0080] [Chemical Formula 4]

[0081]

[0082] Preferably, at least one compound is selected from the compounds shown in formulas (A-2), (A-3), (A-4), (A-5), (A-6), (A-7), (A-8), (A-13), (A-14), (A-15), (A-16), and (A-17). As the polymerizable liquid crystal compound (A), one compound may be used alone, or two or more compounds may be used in combination.

[0083] The polymerizable liquid crystal compound (A) can be manufactured by known methods as described in Lub et al., Recl.Trav.Chim.Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

[0084] Provided that the effects of the present invention are not compromised, the composition for forming a polarizing film may contain polymeric liquid crystal compounds other than polymeric liquid crystal compound (A). From the viewpoint of obtaining a polarizing film with high orientation order, the proportion of polymeric liquid crystal compound (A) relative to the total mass of all polymeric liquid crystal compounds in the composition for forming a polarizing film is preferably 51% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. It may also be entirely (100% by mass) polymeric liquid crystal compound (A).

[0085] When the polarization film forming composition contains two or more polymeric liquid crystal compounds, it is preferable that at least one of them is a polymeric liquid crystal compound (A), or all of the components in the polarization film forming composition may be polymeric liquid crystal compounds (A).

[0086] The content of the polymeric liquid crystal compound in the polarizing film forming composition is preferably 40 to 99.9% by mass, more preferably 60 to 99.9% by mass, and even more preferably 70 to 99% by mass, relative to the solid component of the polarizing film forming composition. If the content of the polymeric liquid crystal compound is within the above range, there is a tendency for the orientation of the polymeric liquid crystal compound to increase. In this specification, the solid component refers to the total amount of components after removing the solvent from the polarizing film forming composition. Hereinafter, when referred to as solid component in this specification, it also refers to the component after removing volatile components such as solvents from the target composition.

[0087] The composition for forming polarizing films also includes a dichroic pigment. Here, a dichroic pigment refers to a pigment that has the property that its absorbance along the long axis of the molecule differs from its absorbance along the short axis. There are no particular limitations on the dichroic pigment as long as it possesses the aforementioned property; it can be either a dye or a pigment. Two or more dyes or pigments can be used separately, or a combination of dyes and pigments can be used. Dichroic pigments can be used alone or in combination. To achieve absorption across the entire visible light spectrum, it is preferable to combine two or more dichroic pigments, and more preferably three or more dichroic pigments. In particular, by mixing two or more dichroic pigments with different absorption wavelengths, polarizing films of various hues can be produced, and polarizing films with absorption across the entire visible light spectrum can be manufactured.

[0088] As a dichroic pigment, it is preferable to have the property of absorbing visible light, and preferably to have a maximum absorption wavelength (λ) in the range of 300–700 nm. MAX Examples of such dichroic pigments include acridine pigments, oxazine pigments, anthocyanins, naphthalene pigments, azo pigments, and anthraquinone pigments. Among these, azo pigments are preferred. Furthermore, from the viewpoint of suppressing pigment degradation, the effects of the present invention become significant when the aforementioned dichroic pigments have absorption at wavelengths below 450 nm. Therefore, the aforementioned dichroic pigments preferably include pigments that have absorption at wavelengths below 450 nm.

[0089] Examples of azo dyes include monoazo dyes, diazo dyes, triazo dyes, tetraazo dyes, and succinylazo dyes, with diazo dyes and triazo dyes being preferred. Examples of compounds represented by formula (I) (hereinafter also referred to as "compound (I)").

[0090] K 1 (-N=NK) 2 ) p -N=NK 3 (I)

[0091] In equation (I), K 1 and K 3Independently representing phenyl groups that may have substituents, naphthyl groups that may have substituents, benzoic acid ester groups that may have substituents, or monovalent heterocyclic groups that may have substituents. K 2 This indicates a p-phenylene group that may have substituents, a naphth-1,4-diyl group that may have substituents, a 4,4'-pyridyl group that may have substituents, or a divalent heterocyclic group that may have substituents. p represents an integer from 0 to 4. When p is an integer greater than 2, multiple K groups are represented. 2 They can be the same or different. Within the visible absorption range, -N=N- bonds can be replaced by -C=C-, -COO-, -NHCO-, or -N=CH- bonds.

[0092] Examples of monovalent heterocyclic groups include those obtained by removing one hydrogen atom from heterocyclic compounds such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of divalent heterocyclic groups include those obtained by removing two hydrogen atoms from the aforementioned heterocyclic compounds.

[0093] As K 1 and K 3 The phenyl, naphthyl, benzoic acid phenyl ester group and monovalent heterocyclic group, as well as K 2 The substituents that can be arbitrarily present in p-phenylene, naphth-1,4-diyl, 4,4'-indene, and divalent heterocyclic groups include alkyl groups with 1 to 20 carbon atoms, alkyl groups with 1 to 20 carbon atoms having polymerizable groups, alkenyl groups with 1 to 4 carbon atoms; alkoxy groups with 1 to 20 carbon atoms such as methoxy, ethoxy, and butoxy; alkoxy groups with 1 to 20 carbon atoms having polymerizable groups; fluoroalkyl groups with 1 to 4 carbon atoms such as trifluoromethyl; cyano; nitro; halogen atoms; substituted or unsubstituted amino groups such as amino, diethylamino, and pyrrolidinyl (substituted amino groups refer to amino groups having 1 or 2 alkyl groups with 1 to 6 carbon atoms, amino groups having 1 or 2 alkyl groups with 1 to 6 carbon atoms, or amino groups with 2 to 8 carbon atoms formed by the bonding of substituted alkyl groups. Unsubstituted amino groups are -NH2). It should be noted that, as examples of the aforementioned polymerizable groups, (meth)acryloyl group, (meth)acryloyloxy group, etc.

[0094] In compound (I), the preferred compound is one of the following formulas (I-1) to (I-8).

[0095] [Chemical Formula 5]

[0096]

[0097] [In formulas (I-1) to (I-8),

[0098] B1 ~B 30 Each can independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of substituted and unsubstituted amino groups are as described above), a chlorine atom, or a trifluoromethyl group.

[0099] n1 to n4 represent integers from 0 to 3 independently.

[0100] When n1 is 2 or more, multiple B 2 They can be the same or different.

[0101] When n² is greater than 2, multiple B 6 They can be the same or different.

[0102] When n3 is 2 or more, multiple B 9 They can be the same or different.

[0103] When n4 is 2 or more, multiple B 14 They can be the same or different.

[0104] The preferred anthraquinone pigment is the compound shown in formula (I-9).

[0105] [Chemical Formula 6]

[0106]

[0107] In equation (I-9),

[0108] R 1 ~R 8 Each independently represents a hydrogen atom, -R x -NH2, -NHR x -NR x 2. -SR x Or halogen atoms.

[0109] R x This refers to an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0110] The preferred compound is shown in formula (I-10).

[0111] [Chemical Formula 7]

[0112]

[0113] In formula (I-10),

[0114] R 9~R 15 Each independently represents a hydrogen atom, -R x -NH2, -NHR x -NR x 2. -SR x Or halogen atoms.

[0115] R x This refers to an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0116] The preferred acridine dye is the compound shown in formula (I-11).

[0117] [Chemical Formula 8]

[0118]

[0119] In formula (I-11),

[0120] R 16 ~R 23 Each independently represents a hydrogen atom, -R x -NH2, -NHR x -NR x 2. -SR x Or halogen atoms.

[0121] R x This refers to an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0122] In equations (I-9), (I-10), and (I-11), R is used as... x Alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, and hexyl, while aryl groups having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, and naphthyl.

[0123] As the aforementioned anthocyanins, the compounds shown in formula (I-12) and formula (I-13) are preferred.

[0124] [Chemical Formula 9]

[0125]

[0126] In equation (I-12),

[0127] D 1 and D 2 The groups represented by any one of formulas (I-12a) to (I-12d) are independently represented.

[0128] [Chemical Formula 10]

[0129]

[0130] n5 represents an integer from 1 to 3.

[0131] [Chemical Formula 11]

[0132]

[0133] In formula (I-13),

[0134] D 3 and D 4 The groups represented by any one of the formulas (1-13a) to (1-13h) are independently represented.

[0135] [Chemical Formula 12]

[0136]

[0137] n6 represents an integer from 1 to 3.

[0138] The weight-average molecular weight of dichroic pigments is typically 300–2000, preferably 400–1000.

[0139] The content of the dichroic pigment in the polarizing film forming composition can be appropriately determined according to the type of dichroic pigment used, etc., and is preferably 1 to 60% by mass, more preferably 1 to 20% by mass, and even more preferably 1 to 15% by mass, relative to the solid content of the polarizing film forming composition. If the content of the dichroic pigment is within the above range, the orientation of the polymerizable liquid crystal compound is not easily disturbed, and a polarizing film with high orientation order can be obtained.

[0140] The composition for forming polarizing films may include a polymerization initiator. The polymerization initiator is a compound capable of initiating polymerization reactions of polymerizable liquid crystal compounds, etc. As a polymerization initiator, a photopolymerization initiator that generates active free radicals or acids through the action of light is preferred, especially one capable of initiating polymerization reactions at lower temperatures; a photopolymerization initiator that generates free radicals through the action of light is more preferred. The polymerization initiator may be used alone or in combination of two or more.

[0141] As photopolymerization initiators, known photopolymerization initiators can be used, such as self-destructive photopolymerization initiators and hydrogen-abstracting photopolymerization initiators that generate active free radicals.

[0142] As self-destructive photopolymerization initiators, self-destructive compounds such as benzoin, acetophenone, hydroxyacetophenone, α-aminoacetophenone, oxime esters, acylphosphine oxides, and azo compounds can be used. Additionally, as hydrogen-abstraction photopolymerization initiators, hydrogen-abstraction compounds such as benzophenone, benzoin ethers, benzoylacetyl ketals, dibenzocycloheptanone, anthraquinones, xanthones, thioxanthones, haloacetophenones, dialkoxyacetophenones, halodiimidazoles, halotriazines, and triazines can be used.

[0143] Iodonium salts and matte salts can be used as photopolymerization initiators that generate acids.

[0144] From the viewpoint of preventing pigment dissolution, a reaction at low temperature is preferred. From the viewpoint of reaction efficiency at low temperature, a self-destructive photopolymerization initiator is preferred, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred.

[0145] Specifically, the following substances can be cited as photopolymerization initiators.

[0146] Benzoin compounds, such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether;

[0147] Oligomers of 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propane-1-one, 1-hydroxycyclohexylphenyl one and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane-1-one, etc., are hydroxyacetophenone compounds.

[0148] α-aminoacetophenone compounds such as 2-methyl-2-morpholino-1-(4-methylthiophenyl)propane-1-one and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1-one;

[0149] 1,2-Octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)], acetone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl oxime) and other oxime ester compounds;

[0150] Acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide;

[0151] Benzophenone, methyl phthalobenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl diphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone and 2,4,6-trimethylbenzophenone and other benzophenone compounds;

[0152] Diethoxyacetophenone and other diekoxyacetophenone compounds;

[0153] 2,4-Bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)vinyl]-1,3,5 Triazine compounds, including 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)vinyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)vinyl]-1,3,5-triazine, and 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)vinyl]-1,3,5-triazine.

[0154] The photopolymerization initiator can be appropriately selected from the aforementioned photopolymerization initiators in relation to the polymerizable liquid crystal compound that forms the polarizing film.

[0155] Alternatively, commercially available photopolymerization initiators can be used. Commercially available polymerization initiators include: Irgacure (イルガキュア) (registered trademark) 907, 184, 651, 819, 250 and 369, 379, 127, 754, OXE01, OXE02, OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, Esacure KIP160 (manufactured by IDM Resins BV); SEIKUOL (registered trademark) BZ, Z and BEE (manufactured by Seiko Chemical Co., Ltd.); kayacure (カヤキュアー) (registered trademark) BP100 and VUI-6992 (manufactured by Dow Chemical Co., Ltd.); ADEKA Optomer SP-152, N-1717, N-1919, SP-170, and ADEKA ARKLS. NCI-831, ADEKA ARKLS NCI-930 (manufactured by ADEKA Co., Ltd.); TAZ-A and TAZ-PP (manufactured by NIHON SIBER HEGNER Co., Ltd.); and TAZ-104 (manufactured by SANWACHEMICAL Co., Ltd.), etc.

[0156] The content of the polymerization initiator is preferably 0.1 to 20 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, more preferably 0.1 to 15 parts by mass, even more preferably 0.5 to 10 parts by mass, and particularly preferably 0.5 to 8 parts by mass. If the content of the polymerization initiator is within the above range, the polymerization reaction can be carried out without significantly disturbing the orientation of the polymerizable liquid crystal compound.

[0157] The polarizing film forming composition may include a leveling agent. The leveling agent functions to adjust the flowability of the polarizing film forming composition and to make the coating obtained by applying the composition smoother. Specifically, surfactants are an example. Preferably, the leveling agent is selected from at least one of leveling agents mainly composed of polyacrylate compounds and leveling agents mainly composed of fluorine-containing compounds. Leveling agents may be used alone or in combination of two or more.

[0158] Examples of leveling agents that are mainly composed of polyacrylate compounds include BYK-350, BYK-352, BYK-353, BYK-354, BYK-355, BYK-358N, BYK-361N, BYK-380, BYK-381 and BYK-392 (BYK Chemie).

[0159] Examples of leveling agents whose main component is a compound containing fluorine atoms include Megaface (registered trademark) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-470, F-471, F-477, F-479, F-482, F-483, and F-556 (DIC Corporation); Surflon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH-40, and SA-100 (AGC Seimi Chemical Co., Ltd.); E1830 and E5844 (Daikin FineChemical Research Institute, Ltd.); Eftop EF301, Eftop EF303, Eftop EF351, and Eftop EF352 (Mitsubishi Material Electronic Chemical Co., Ltd.).

[0160] When the composition for forming the polarizing film contains a leveling agent, its content is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the polymeric liquid crystal compound, more preferably 0.05 to 3 parts by mass. If the content of the leveling agent is within the above range, there is a tendency to easily orient the polymeric liquid crystal compound, reduce the likelihood of unevenness, and obtain a smoother polarizing film.

[0161] The composition for forming a polarizing film may contain additives other than leveling agents. Examples of such additives include polymerizable non-liquid crystal compounds, photosensitizers, antioxidants, release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When other additives are included, their content is preferably more than 0% and less than 20% by mass relative to the solid content of the composition for forming a polarizing film, more preferably more than 0% and less than 10% by mass.

[0162] The polarizing film forming composition can be manufactured using conventional liquid crystal composition preparation methods. It is typically prepared by mixing and stirring a polymerizable liquid crystal compound, a dichroic pigment, a desired polymerization initiator, and the aforementioned additives. Furthermore, liquid crystal compounds that generally exhibit smectic liquid crystal properties have high viscosity; therefore, from the viewpoint of improving the coatability of the liquid crystal composition to facilitate the formation of a polarizing film, the viscosity can be adjusted by adding a solvent to the composition.

[0163] The solvent can be appropriately selected based on the solubility of the polymerizable liquid crystal compound and dichroic pigment used, and preferably a solvent that can completely dissolve the above components and is inactive to the polymerization reaction.

[0164] As solvents, examples include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or 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; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; carbonate solvents such as ethylene carbonate and propylene carbonate; and pyrrolidone solvents such as N-methylpyrrolidone. These solvents can be used alone or in combination of two or more.

[0165] The solvent content is preferably 100 to 1900 parts by mass relative to 100 parts by mass of the solid component of the composition for forming the polarizing film, more preferably 150 to 1000 parts by mass, and even more preferably 180 to 800 parts by mass.

[0166] In this invention, the cured layer formed by the polarizing film forming composition is preferably a liquid crystal cured film with a high degree of orientation order. A liquid crystal cured film with a high degree of orientation order can produce Bragg peaks from higher-order structures such as hexagonal phases and crystalline phases in X-ray diffraction measurements. A Bragg peak refers to a peak arising from a planar periodic structure of molecular orientation. Therefore, the polarizing film (cured layer) constituting the polarizing plate of this invention preferably displays a Bragg peak in X-ray diffraction measurements. That is, in this invention, the polarizing film (cured layer) is preferably oriented in a manner that allows the film to display a Bragg peak in X-ray diffraction measurements. In one embodiment of this invention, the planar periodic interval of molecular orientation is preferably 3.0 to 6.0 Å. A high degree of orientation order, such as displaying a Bragg peak, can be achieved by controlling the type of polymeric liquid crystal compound used, the type and amount of dichroic pigment, and the type and amount of polymerization initiator, etc.

[0167] In this invention, the polarizing film may include an alignment film. The alignment film has an orientation-restricting force that orients the polymerizable liquid crystal compound in a desired direction. By coating the polarizing film forming composition onto the alignment film, a polarizing film (cured layer) with good orientation precision can be easily obtained. Preferably, the alignment film has solvent resistance that prevents dissolution due to coating of the aforementioned polarizing film forming composition, and heat resistance in heat treatments for solvent removal and orientation of the polymerizable liquid crystal compound. Furthermore, a small difference in refractive index between the alignment film and the protective film is preferable.

[0168] Examples of orientation films include orientation films containing orientation polymers, photo-oriented films, grooved orientation films with raised or recessed patterns or multiple grooves on the surface, and stretched films stretched along the orientation direction. These various orientation films can be appropriately selected from those conventionally known in the field based on the desired orientation restraint force.

[0169] In one embodiment of the invention, a photoalignment film is preferred from the viewpoints of improving alignment accuracy and adhesion to the cured layer formed by the composition for forming a polarizing film. The photoalignment film is also advantageous because the direction of the alignment restraint force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

[0170] Photoalignment films are typically obtained by coating a composition (hereinafter also referred to as a "photoalignment film forming composition") containing a polymer, oligomer, or monomer having photoreactive groups and a solvent onto a substrate or the like, and then irradiating it with polarized light (preferably polarized UV light). If the polymer or the like contained in the photoalignment film forming composition has the same reactive groups (e.g., (meth)acryloyl groups) as the functional groups of the polymeric liquid crystal compound that forms the polarized film, there is a tendency for improved adhesion between the cured layer of the polymeric liquid crystal compound and the alignment film.

[0171] Photoreactive groups are groups that generate liquid crystal alignment ability through light irradiation. Specifically, examples include photoreactive groups that participate in orientation-inducing or isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodecomposition reactions of molecules generated by light irradiation, thus becoming 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 photoreactive groups, groups having unsaturated bonds, especially double bonds, are preferred, and groups having at least one selected from 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) are particularly preferred.

[0172] Specifically, as such an alignment film, for example, the optical alignment film described in Japanese Patent Application Publication No. 2020-56834 and Japanese Patent Application Publication No. 2021-196514 can be used.

[0173] The thickness of the alignment film is preferably 10–3000 nm, more preferably 10–1000 nm, further preferably 10–500 nm, even more preferably 10–300 nm, and particularly preferably 30–300 nm. If the thickness of the alignment film is within the above range, it exhibits good adhesion at the interface with the cured layer formed from the polarization film forming composition formed on the alignment film, and exerts an orientation regularity force, enabling the formation of a polarization film with high orientation order. The thickness of the alignment film can be measured using an ellipsometer.

[0174] Polarizing films can be manufactured, for example, by a method including the following steps:

[0175] The step of forming a coating film of the composition for forming a polarizing film;

[0176] The step of removing the solvent from the above coating film;

[0177] The steps include heating the liquid crystal compound to a temperature above which the polymeric liquid crystal compound phase transforms into a liquid phase, and then cooling it to transform the polymeric liquid crystal compound phase into a liquid crystal phase (e.g., a smectic liquid crystal phase); and...

[0178] The step of polymerizing a polymerizable liquid crystal compound while maintaining the above-described liquid crystal phase.

[0179] The formation of a coating film of the polarizing film forming composition can be achieved, for example, by coating the polarizing film forming composition onto a substrate, an alignment film, or the like. The substrate can be a layer constituting the polarizing plate of the present invention, but in one embodiment of the present invention, it is preferred to be a layer that is ultimately peeled off.

[0180] As a substrate, conventionally known resin film substrates used in the field of optical films can be used. Specifically, examples of resins constituting such resin films include polyolefin resins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; poly(meth)acrylic acid resins such as poly(meth)acrylate and poly(meth)acrylate; cellulose ester resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; vinyl alcohol resins such as polyvinyl alcohol and polyvinyl acetate; polycarbonate resins; polystyrene resins; polyaryl ester resins; polysulfone resins; polyethersulfone resins; polyamide resins; polyimide resins; polyetherketone resins; polyphenylene sulfide resins; polyphenylene ether resins; and mixtures thereof. These resins can be used alone or in combination of two or more. Such resins can be used to form resin film substrates by solvent casting, melt extrusion, or other known methods. In addition, commercially available products can be used as the membrane substrate or the resin constituting the membrane substrate. Surface treatments such as corona treatment and plasma treatment can be applied to the membrane substrate, and demolding treatment can be performed after the substrate is peeled off.

[0181] There are no particular limitations on the thickness of the substrate; any appropriate thickness within a practical range can be selected. For example, it can be approximately 5μm to 300μm.

[0182] There are no particular limitations on the method for forming the polarizing film by coating the composition. Known methods such as spin coating, extrusion, gravure coating, die coating, rod coating, applicator coating, and flexographic printing can be used.

[0183] When the composition for forming a polarizing film contains a solvent, the solvent is usually removed from the coated composition. Methods for solvent removal include natural drying, ventilation drying, heating drying, and reduced pressure drying. The coating is preferably dried such that the residual solvent in the polarizing film is less than 1% by weight relative to the total mass of the polarizing film. The amount of residual solvent can be quantified by peeling the polarizing film off a substrate and weighing it, immersing the polarizing film in a solvent such as tetrahydrofuran that dissolves the polarizing film, irradiating it with ultrasound for about 10 minutes to extract the dissolved components, and then analyzing the solution using gas chromatography. The drying temperature and drying time, among other conditions, can be appropriately determined based on the composition of the polarizing film forming composition, the substrate, and the material of the alignment film.

[0184] The polymeric liquid crystal compound in the coating is usually heated to a temperature above the temperature at which it transforms into a liquid crystal state or solution state, and then cooled to the temperature at which liquid crystal orientation occurs, thereby orienting together with the dichroic pigment to form a liquid crystal phase.

[0185] The temperature for aligning the polymeric liquid crystal compound in the coating film can be determined in advance by observing the texture of the composition containing the polymeric liquid crystal compound. Alternatively, solvent removal and liquid crystal alignment can be performed simultaneously. While the temperature at this time depends on the solvent removed and the type of polymeric liquid crystal compound used, it is preferably in the range of 50–200°C, and more preferably in the range of 80–130°C.

[0186] While maintaining the liquid crystal state of the polymeric liquid crystal compound, the polymeric liquid crystal compound is polymerized and cured, thereby forming a polarizing film as a cured layer of the liquid crystal composition. Photopolymerization is preferred as the polymerization method. In photopolymerization, the light used to irradiate the dried film is appropriately selected based on the type of polymeric liquid crystal compound contained in the dried film (especially the type of polymeric groups possessed by the polymeric liquid crystal compound), the type of polymerization initiator, and their amounts. Compared to conventional host-guest type liquid crystal cured layers, i.e., liquid crystal cured layers obtained by polymerizing polymeric liquid crystal compounds while maintaining a smectic liquid crystal phase, the cured layer containing the polymeric liquid crystal compound polymerized in a state of maintaining a nematic liquid crystal phase, exhibits higher polarization performance. Furthermore, compared to cured layers coated only with dichroic pigments or lyotropic liquid crystals, it demonstrates superior polarization performance and film strength.

[0187] (Protective layer)

[0188] The polarizing plate of the present invention includes a protective layer adjacent to the aforementioned horizontal polarizing film. By including the protective layer, the strength of the horizontal polarizing film can be enhanced, and the diffusion of dichroic pigments can be suppressed.

[0189] In one embodiment of the present invention, the protective layer is preferably a layer formed from a protective layer forming composition containing an active energy ray curable component. Examples of active energy ray curable components include cationic polymeric compounds and free radical polymeric compounds. Specific examples of cationic polymeric compounds include epoxy compounds having one or more epoxy groups within the molecule, oxetane compounds having one or more oxetane rings within the molecule, and vinyl compounds. Specific examples of free radical polymeric compounds include (meth)acrylic acid compounds having one or more (meth)acryloyl groups within the molecule, and vinyl compounds.

[0190] The protective layer is a cured layer of a curable composition comprising a polymeric compound (e.g., a free radical polymeric compound and / or a cationic polymeric compound). The protective layer preferably has a thickness of 0.2–5 μm, more preferably 0.5–4 μm, further preferably 0.7–3 μm, and even more preferably 1–2.5 μm. The polarizing plate of the present invention uses a cured layer of a polymeric compound adjacent to the polarizing film as a protective layer, thereby suppressing the diffusion of dichroic pigments in polarizing films formed using polymeric liquid crystal compositions comprising polymeric liquid crystal compounds and dichroic pigments.

[0191] In a preferred embodiment of the present invention, the protective layer forming composition may contain a cationic polymeric compound as an active energy ray curable component. When the protective layer forming composition contains a cationic polymeric compound, in polarizing films formed using a polymeric liquid crystal composition containing a polymeric liquid crystal compound and a dichroic pigment, the diffusion of the dichroic pigment can be suppressed, and even with a thin polarizing film and protective layer, the curling of the polarizing plate can be suppressed. In polarizing films using dichroic pigments, a protective layer is sometimes provided to prevent the diffusion of the dichroic pigment, but curling sometimes occurs, especially in the case of thin polarizing films. When using free radical polymeric compounds that easily produce curing shrinkage, for example, when lamination is performed by heating, it is sometimes difficult to suppress curling, but by providing a protective layer as a cured layer of a curable composition containing a cationic polymeric compound, the diffusion of the dichroic pigment can be sufficiently suppressed, and curling can be suppressed.

[0192] The following describes the case where the curable composition for forming a protective layer (hereinafter also referred to as the "composition for forming a protective layer") contains a cationic polymerizable compound. The cationic polymerizable compound contained in the composition for forming the protective layer refers to a compound or oligomer that undergoes a cationic polymerization reaction and is cured by irradiation or heating with active energy rays such as ultraviolet light, visible light, electron beams, or X-rays. Examples include epoxy compounds, oxetane compounds, and vinyl compounds. Preferably, the cationic polymerizable compound is a polymerizable compound having a cyclic ether structure, and more preferably a polymerizable compound having epoxy groups and / or oxetane groups.

[0193] Polymerizable compounds with epoxy groups (also called "epoxide compounds") refer to compounds having one or more epoxy groups, preferably two or more, within their molecules. An epoxy compound can be used alone or in combination of two or more. Examples of epoxy compounds include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. From the viewpoint of suppressing curling, weather resistance, and reduction in curing speed, epoxy compounds preferably include alicyclic epoxy compounds and / or aliphatic epoxy compounds.

[0194] Alicyclic epoxides are compounds that have one or more epoxy groups bonded to an alicyclic ring within the molecule. Examples include alicyclic epoxides with cyclopentane or cyclohexane oxide structures. Specifically, examples include 3,4-epoxycyclohexanecarboxylic acid (3,4-epoxycyclohexylmethyl ester), 3,4-epoxy-6-methylcyclohexanecarboxylic acid (3,4-epoxy-6-methylcyclohexylmethyl ester), ethylene bis(3,4-epoxycyclohexanecarboxylic acid ester), bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, and diethylene glycol bis(3,4-epoxycyclohexylmethyl ether). Ethylene glycol bis(3,4-epoxycyclohexyl methyl ether), 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro[5.2.2.5.2.2]eicosene, 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5]undecane, 4-vinylcyclohexene dioxide, limonene dioxide, bis(2,3-epoxycyclopentyl) ether, dicyclopentadiene dioxide, etc.

[0195] Aromatic epoxy compounds are compounds that have an aromatic ring and an epoxy group within their molecules. Specific examples include bisphenol-type epoxy compounds or their oligomers, such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether; phenolic epoxy resins, such as phenol-formaldehyde epoxy resin, cresol-formaldehyde epoxy resin, and hydroxybenzaldehyde-phenol-formaldehyde epoxy resin; multifunctional epoxy compounds, such as 2,2',4,4'-tetrahydroxydiphenylmethane glycidyl ether and 2,2',4,4'-tetrahydroxybenzophenone glycidyl ether; and multifunctional epoxy resins, such as epoxidized polyvinylphenol.

[0196] Hydrogenated epoxy compounds are glycidyl ethers of polyols with alicyclic rings. They can be obtained by selectively hydrogenating the aromatic ring of an aromatic polyol under pressure in the presence of a catalyst to obtain a nucleus-hydrogenated polyhydroxy compound, and then glycidyl etherifying this nucleus-hydrogenated polyhydroxy compound. Specific examples of aromatic polyols include bisphenol-type compounds such as bisphenol A, bisphenol F, and bisphenol S; phenolic resins such as phenol-formaldehyde resin, cresol-formaldehyde resin, and hydroxybenzaldehyde-phenol-formaldehyde resin; and multifunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol. Glycidyl ethers can be prepared by reacting alicyclic polyols obtained by hydrogenating the aromatic ring of an aromatic polyol with epichlorohydrin; for example, diglycidyl ether of hydrogenated bisphenol A can be cited.

[0197] Aliphatic epoxides are compounds that have at least one ethylene oxide ring (a three-membered cyclic ether) bonded to an aliphatic carbon atom within their molecule. Examples include monofunctional epoxides such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether; difunctional epoxides such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; trifunctional or more functional epoxides such as trimethylolpropane triglycidyl ether and pentaerythritol tetraglycidyl ether; and epoxides such as 4-vinylcyclohexene dioxide and limonene dioxide, which have one epoxy group directly bonded to an alicyclic ring and an ethylene oxide ring bonded to an aliphatic carbon atom. Preferably, difunctional epoxides have two ethylene oxide rings bonded to aliphatic carbon atoms within their molecule (also known as aliphatic diesters).

[0198] Polymerizable compounds containing an oxetane group (also known as "oxetane compounds") are compounds containing one or more oxetane rings (oxetane groups) within their molecules. Specific examples include 3-ethyl-3-hydroxymethyloxetane (also known as oxetane alcohol), 2-ethylhexyloxetane, 1,4-bis[{(3-ethyloxetane-3-yl)methoxy}methyl]benzene (also known as xylenedioxetane), 3-ethyl-3[{(3-ethyloxetane-3-yl)methoxy}methyl]oxetane, 3-ethyl-3-(phenoxymethyl)oxetane, and 3-(cyclohexyloxy)methyl-3-ethyloxetane. Oxetane compounds can be used as the main component of cationic polymerizable compounds or in combination with epoxy compounds. By using oxetane compounds in combination, the curing speed of the protective layer can be improved and pigment diffusion can be inhibited.

[0199] Vinyl compounds that can be cationic polymers include aliphatic or alicyclic vinyl ethers. Specific examples include vinyl ethers of alkyl or alkenyl alcohols with 5 to 20 carbon atoms, such as n-pentyl vinyl ether, isopentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, and oleyl vinyl ether; hydroxyl-containing vinyl ethers such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, and 4-hydroxybutyl vinyl ether; vinyl ethers of monohydric alcohols having aliphatic or aromatic rings, such as cyclohexyl vinyl ether, 2-methylcyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, and benzyl vinyl ether; and glycerol monovinyl ether, 1,4-butanediol monovinyl ether, and 1,4-butanediol divinyl ether. Vinyl ethers include mono- and polyvinyl ethers of polyols such as ethers, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol tetravinyl ether, trimethylolpropane divinyl ether, trimethylolpropane trivinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxymethylcyclohexane monovinyl ether, and 1,4-dihydroxymethylcyclohexane divinyl ether; mono- or divinyl ethers of polyalkylene glycols such as diethylene glycol divinyl ether, triethylene glycol divinyl ether, and diethylene glycol monobutyl monovinyl ether; and other vinyl ethers such as glycidyl vinyl ether and ethylene glycol vinyl ether methacrylate. Vinyl compounds can be used as the main component of cationic polymerizable compounds, or in combination with epoxy compounds, or epoxy compounds and oxetane compounds. Combining vinyl compounds can improve the curing speed and reduce the viscosity of the protective layer.

[0200] In addition to the polymerizable compounds described above, the composition for forming the protective layer may further include other cationic polymerizable compounds other than those described above, such as cyclic lactone compounds, cyclic acetal compounds, cyclic sulfide compounds, and spirocyclic orthoester compounds.

[0201] In one embodiment of the invention, from the viewpoint of suppressing curling, the composition for forming the protective layer preferably comprises an epoxy compound and / or an oxetane compound as cationic polymerizable compounds. In this case, the content of the epoxy compound and / or oxetane compound (the total content when two or more are included) is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, and can be 100% by mass, relative to 100% by mass.

[0202] In a preferred embodiment of the invention, from the viewpoint of suppressing curling and the diffusion of dichroic pigments, the composition for forming the protective layer preferably includes an oxetane compound as a cationic polymerizable compound. In this case, relative to 100% by mass of the total amount of the cationic polymerizable compound, the content of the oxetane compound (the total content when two or more are included) is preferably 10% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, even more preferably 50% by mass or more, particularly preferably 60% by mass or more, for example, 70% by mass or more, 80% by mass or more, or even 100% by mass.

[0203] The content of cationic polymeric compounds contained in the protective layer forming composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, relative to the amount of solid components in the protective layer forming composition.

[0204] From the viewpoint of suppressing the diffusion of dichroic pigments in the obtained polarizing plates and circular polarizing plates, the content of aromatic cationic polymeric compounds, such as aromatic epoxy compounds and / or aromatic oxobutane compounds in the protective layer forming composition is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less, relative to 100% by mass of the total amount of cationic polymeric compounds contained in the protective layer forming composition.

[0205] The composition for forming the protective layer preferably also contains a photocationic polymerization initiator. The photocationic polymerization initiator generates cationic species or Lewis acids by irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams, initiating the polymerization reaction of the cationic curable compound. The photocationic polymerization initiator exerts its catalytic effect through light, therefore exhibiting excellent storage stability and workability even when mixed into the photocationic curable compound. Examples of compounds that generate cationic species or Lewis acids by irradiation with active energy rays include, for example, aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, and iron-aromatic complexes.

[0206] Aromatic iodonium salts are compounds containing a diaryliodonium cation; typical examples of this cation include diphenyliodonium. Aromatic sulfonium salts are compounds containing a triarylsulfonium cation; typical examples of this cation include triphenylsulfonium and 4,4'-bis(diphenylsulfonyl)diphenyl sulfide. Aromatic diazonium salts are compounds containing a diazonium cation; typical examples of this cation include benzenediazonium. Additionally, iron-aromatic complexes are typically cyclopentadienyl iron(II)aromatic cation complexes.

[0207] The cations and anions shown above pair to form photocationic polymerization initiators. Examples of anions that constitute photocationic polymerization initiators include specific phosphorus-based anions [(Rf]]. n PF 6-n ] - hexafluorophosphate anion PF6 - SbF6, anion of hexafluoroantimonate - The pentafluorohydroxyantimonate anion SbF5(OH) - AsF6 hexafluoroarsenate anion - Tetrafluoroborate anion BF4 - Tetra(pentafluorophenyl)borate anion B(C6F5)4 - Etc. Among these, from the viewpoint of the curability of cationic polymeric compounds and the safety of the resulting protective layer, special phosphorus-based anions [(Rf)] are preferred. n PF 6-n ] - hexafluorophosphate anion PF6 - .

[0208] Photocationic polymerization initiators can be used alone or in combination of two or more. Among them, aromatic sulfonium salts exhibit ultraviolet absorption characteristics even in the wavelength region around 300 nm, thus exhibiting excellent curability and forming a protective layer with good mechanical strength, making them a suitable choice.

[0209] The content of the photocationic polymerization initiator in the protective layer forming composition is preferably 1 to 10% by mass, more preferably 2 to 8% by mass, relative to the solid content of the composition. If the content of the photocationic polymerization initiator is within the above range, the cationic polymerizable compound can be fully cured, the resulting protective layer can be endowed with high mechanical strength, and the curl suppression effect can be improved.

[0210] In another embodiment of the invention, the protective layer forming composition may include a free radical polymerizable compound as an active energy ray curable component. In this embodiment, it is more preferable to include (meth)acrylic acid compounds, and even more preferable to include polyfunctional (meth)acrylic acid ester compounds. From the viewpoint of inhibiting pigment diffusion, (meth)acrylic acid compounds, especially polyfunctional (meth)acrylic acid ester compounds, are preferred.

[0211] (Meth)acrylic acid compounds are compounds having at least one (meth)acryloyloxy group within their molecule, and can be monomers, oligomers, or polymers. Examples of (meth)acrylic acid compounds include, for instance, monofunctional (meth)acrylate compounds, polyfunctional (meth)acrylate compounds, urethane (meth)acrylate compounds, polyfunctional urethane (meth)acrylate compounds, epoxy (meth)acrylate compounds, polyfunctional epoxy (meth)acrylate compounds, carboxyl-modified epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, etc. A single (meth)acrylic acid compound can be used alone, or two or more compounds can be used in combination. In this specification, "(meth)acrylate" refers to "acrylate" or "methacrylate," and "(meth)acryloyl" also refers to "acryloyl" or "methacryloyl."

[0212] Examples of (meth)acrylate compounds include monofunctional (meth)acrylate compounds having one (meth)acryloyloxy group in the molecule and polyfunctional (meth)acrylate compounds having two or more (meth)acryloyloxy groups in the molecule.

[0213] Examples of monofunctional (meth)acrylate monomers include alkyl (meth)acrylates. In alkyl (meth)acrylates, when the alkyl group has 3 or more carbon atoms, it can be either straight-chain or branched. Specific examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. In addition, aralkyl methacrylates such as benzyl methacrylate; terpene alcohol methacrylates such as isobornyl methacrylate; methacrylates with a tetrahydrofurfuryl structure such as tetrahydrofurfuryl methacrylate; methacrylates with a cycloalkyl group at the alkyl site such as cyclohexyl methacrylate, cyclohexylmethyl methacrylate, dicyclopentyl acrylate, dicyclopentenyl methacrylate, and 1,4-cyclohexanediethanol monoacrylate; aminoalkyl methacrylates such as N,N-dimethylaminoethyl methacrylate; and methacrylates with an ether bond at the alkyl site such as 2-phenoxyethyl methacrylate, dicyclopentenoxyethyl methacrylate, ethyl carbitol methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, and phenoxy polyethylene glycol methacrylate can also be used as monofunctional methacrylate monomers.

[0214] Examples of difunctional (meth)acrylate monomers include alkylene glycol dimethacrylates such as ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, and neopentyl glycol dimethacrylate; diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, and polyethylene glycol dimethacrylate; and polyethylene glycol dimethacrylate. Di(meth)acrylates of polyoxyalkylene glycols, such as diol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate; di(meth)acrylates of halogen-substituted alkylene glycols, such as tetrafluoroethylene glycol di(meth)acrylate; di(meth)acrylates of aliphatic polyols, such as trimethylolpropane di(meth)acrylate, di(trimethylolpropane)di(meth)acrylate, and pentaerythritol di(meth)acrylate; hydrogenated dicyclopentadienyl di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, etc. Di(meth)acrylates of hydrogenated dicyclopentadiene or tricyclodecanediols, such as 1,3-dioxane-2,5-diyldi(meth)acrylate (also known as dioxanediol di(meth)acrylate), and di(meth)acrylates of dioxanediols or dioxanediols; di(meth)acrylates of bisphenol A or bisphenol F ethylene oxide adducts, such as ethylene oxide adducts of bisphenol A or bisphenol F; acrylic adducts of bisphenol A diglycidyl ether and bisphenol F diglycidyl ether. Products such as bisphenol A or bisphenol F epoxy di(meth)acrylates; organosilicon di(meth)acrylates; neopentyl glycol hydroxypentanoate di(meth)acrylates; 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane; 2,2-bis[4-(meth)acryloyloxyethoxyethoxycyclohexyl]propane; 2-(2-hydroxy-1,1-dimethylethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane) di(meth)acrylates; tri(hydroxyethyl)isocyanurate di(meth)acrylates, etc.

[0215] Trifunctional (meth)acrylate monomers are monomers that have three (meth)acryloyloxy groups in their molecule. Examples include glycerol trimethacrylate, trimethylolpropane trimethacrylate, di(trimethylolpropane)trimethacrylate, pentaerythritol trimethacrylate, the reaction product of pentaerythritol trimethacrylate and acid anhydride, caprolactone-modified trimethylolpropane trimethacrylate, caprolactone-modified pentaerythritol trimethacrylate, and ethylene oxide-modified trimethacrylate. Hydroxymethyl propane tri(meth)acrylate, ethylene oxide modified pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, propylene oxide modified pentaerythritol tri(meth)acrylate, isocyanurate tri(meth)acrylate, caprolactone modified pentaerythritol tri(meth)acrylate reacting with acid anhydrides, ethylene oxide modified pentaerythritol tri(meth)acrylate reacting with acid anhydrides, propylene oxide modified pentaerythritol tri(meth)acrylate reacting with acid anhydrides, etc.

[0216] Four-functional (meth)acrylate monomers are monomers that have four (meth)acryloyloxy groups in their molecules. Examples of such monomers include di(trimethylolpropane)tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, tripentaerythritol tetra(meth)acrylate, caprolactone-modified pentaerythritol tetra(meth)acrylate, caprolactone-modified tripentaerythritol tetra(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, ethylene oxide-modified tripentaerythritol tetra(meth)acrylate, propylene oxide-modified pentaerythritol tetra(meth)acrylate, and propylene oxide-modified tripentaerythritol tetra(meth)acrylate.

[0217] Examples of 5-functional (meth)acrylate monomers include dipentaerythritol pentamethacrylate, tripentaerythritol pentamethacrylate, the reaction product of dipentaerythritol pentamethacrylate and acid anhydride, caprolactone-modified dipentaerythritol pentamethacrylate, caprolactone-modified tripentaerythritol pentamethacrylate, ethylene oxide-modified dipentaerythritol pentamethacrylate, ethylene oxide-modified tripentaerythritol pentamethacrylate, propylene oxide-modified dipentaerythritol pentamethacrylate, propylene oxide-modified tripentaerythritol pentamethacrylate, caprolactone-modified dipentaerythritol pentamethacrylate and acid anhydride, ethylene oxide-modified dipentaerythritol pentamethacrylate and acid anhydride, and propylene oxide-modified dipentaerythritol pentamethacrylate and acid anhydride.

[0218] Examples of hexafunctional (meth)acrylate monomers include dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified tripentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified tripentaerythritol hexa(meth)acrylate, propylene oxide-modified dipentaerythritol hexa(meth)acrylate, and propylene oxide-modified tripentaerythritol hexa(meth)acrylate.

[0219] Examples of hexafunctional (meth)acrylate monomers include tripentaerythritol heptamethacrylate, reactants of tripentaerythritol heptamethacrylate with acid anhydrides, caprolactone-modified tripentaerythritol heptamethacrylate, reactants of caprolactone-modified tripentaerythritol heptamethacrylate with acid anhydrides, ethylene oxide-modified tripentaerythritol heptamethacrylate, reactants of ethylene oxide-modified tripentaerythritol heptamethacrylate with acid anhydrides, propylene oxide-modified tripentaerythritol heptamethacrylate, and reactants of propylene oxide-modified tripentaerythritol heptamethacrylate with acid anhydrides.

[0220] 8-functional (meth)acrylate monomers are monomers that have 8 (meth)acryloyloxy groups in the molecule. Examples of such monomers include tripentaerythritol octa(meth)acrylate, caprolactone-modified tripentaerythritol octa(meth)acrylate, ethylene oxide-modified tripentaerythritol octa(meth)acrylate, and propylene oxide-modified tripentaerythritol octa(meth)acrylate.

[0221] When using polyfunctional (meth)acrylate compounds, the crosslinking density of the cured resin layer can be adjusted by controlling the molecular weight between crosslinking points and the number of crosslinking points. More specifically, the smaller the molecular weight between crosslinking points, the higher the crosslinking density; conversely, the more crosslinking points, the denser the crosslinking density. This also improves the diffusion inhibition function of dichroic pigments in polarizing films.

[0222] Carbamate (meth)acrylate compounds generally refer to reactants of isocyanate compounds, polyol compounds, and (meth)acrylate compounds, and are preferably polyfunctional carbamate (meth)acrylate compounds having two or more (meth)acryloyloxy groups within the molecule. Polyfunctional carbamate (meth)acrylate compounds can form cross-linked structures, which is advantageous from the viewpoint of improving adhesion to polarizing films, inhibiting the diffusion of dichroic pigments, and imparting moderate toughness. The number of functional groups in the polyfunctional carbamate (meth)acrylate compound is preferably 2 to 5.

[0223] In one embodiment of the present invention, from the viewpoint of suppressing pigment diffusion, the composition for forming the protective layer preferably comprises a polyfunctional (meth)acrylate compound and a urethane (meth)acrylate compound as free radical polymerizable compounds. In this case, it is preferable to include the polyfunctional (meth)acrylate compound and the urethane (meth)acrylate compound in a ratio preferably 95:5 to 50:50, more preferably 90:10 to 70:30 (polyfunctional (meth)acrylate compound: urethane (meth)acrylate compound, mass ratio). By including the polyfunctional (meth)acrylate compound and the urethane (meth)acrylate compound in the above-mentioned mixing ratio, the adhesion to the polarizing film is easily improved. The urethane (meth)acrylate compound is preferably a polyfunctional urethane (meth)acrylate compound. The urethane (meth)acrylate compound can be a resin such as an oligomer.

[0224] In one embodiment of the present invention, when the composition for forming the cured resin layer contains a free radical polymerizable compound, it is preferable to include a (meth)acrylate compound as a free radical polymerizable compound, and more preferably, a polyfunctional (meth)acrylate compound. In this case, the content of the (meth)acrylate compound (the total content when two or more are included) relative to 100% by mass of the total free radical polymerizable compound is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. If the content of the (meth)acrylate compound, especially the polyfunctional (meth)acrylate compound, is within the above range, the diffusion inhibition function of the dichroic pigment can be improved.

[0225] Furthermore, in the above embodiments, the composition for forming the cured resin layer preferably further comprises a urethane (meth)acrylate compound as a free radical polymerizable compound. In this case, relative to 100% by mass of the total amount of the free radical polymerizable compound, the content of the urethane (meth)acrylate compound is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. If the content of the urethane (meth)acrylate compound is within the above range, the adhesion to the polarizing film and the diffusion inhibition function of the dichroic pigment can be improved.

[0226] In one embodiment of the present invention, when the composition for forming the cured resin layer contains a monofunctional (meth)acrylate compound, from the viewpoint of adhesion to the polarizing film, its content (the total content of two or more compounds) is preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and even more preferably 10% by mass or less, relative to 100% by mass of the total amount of the free radical polymerizable compound.

[0227] When the composition for forming the cured resin layer contains a free radical polymerizable compound, it preferably contains a photoradical polymerization initiator. A photoradical polymerization initiator is an initiator that initiates the polymerization reaction of a free radical curable compound by irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams. A single photoradical polymerization initiator may be used alone, or two or more may be used in combination.

[0228] Specific examples of photoradical polymerization initiators include acetophenone, 3-methylacetophenone, benzoyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one, and 2-hydroxy-2-methyl-1-phenylpropane-1-one, among other acetophenone-based initiators; benzophenone, 4-chlorobenzophenone, and 4,4'-diaminodiphenyl ether... Initiators include benzophenone and other benzophenone-based initiators; alkyl benzophenone-based initiators such as 2,2-dimethoxy-1,2-diphenylethane-1-one and 1-hydroxy-cyclohexyl-phenyl-one; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; acylphosphine oxide-based initiators such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and xanthones, fluorenone, camphorquinone, benzaldehyde, anthraquinone, etc.

[0229] The content of the photoradical polymerization initiator in the protective layer forming composition is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, relative to 100 parts by mass of the solid component of the curable compound. If the content of the photoradical polymerization initiator is within the above range, the polymerization initiation ability can be sufficiently manifested, and the curability can be improved.

[0230] The composition for forming the protective layer may contain additives such as cationic polymerization accelerators, photosensitizers, ion scavengers, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow modifiers, plasticizers, defoamers, antistatic agents, and leveling agents, as needed.

[0231] The composition for forming the protective layer may contain an organic solvent to adjust the viscosity to suit the application method, or it may be substantially solvent-free (solvent-free). It should be noted that "substantially solvent-free" does not exclude the possibility of unavoidable solvent contamination.

[0232] As a solvent, any solvent capable of dissolving the components of the composition constituting the protective layer can be used. For example, appropriate selections can be made from aliphatic hydrocarbons such as hexane and octane; aromatic hydrocarbons such as toluene and xylene; alcohols such as ethanol, 1-propanol, isopropanol, and 1-butanol; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate, butyl acetate, and isobutyl acetate; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; and esterified glycol ethers such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate. These solvents can be used alone or in combination of two or more.

[0233] The type and content of the solvent are appropriately selected based on the type, content, shape, coating method, and thickness of the cured resin layer of the components constituting the composition for forming the protective layer. When a solvent is included, its amount is preferably 3 to 1000 parts by weight relative to 100 parts by weight of the solid components of the composition for forming the cured resin layer, more preferably 5 to 100 parts by weight, and even more preferably 7 to 50 parts by weight.

[0234] The protective layer can be manufactured by a method including the following steps:

[0235] The step of forming a protective layer coating of the composition on the horizontally polarizing film manufactured as described above;

[0236] The step of removing the solvent from the above coating film;

[0237] The step of polymerizing a cationic polymeric compound or a free radical polymeric compound contained in the composition to form a protective layer.

[0238] The method for forming the protective layer composition is not particularly limited. The composition can be applied to the polarizing film manufactured as described above, using the same method as for applying the polarizing film forming composition. When the protective layer forming composition contains a solvent, the solvent is typically removed from the coated composition. Examples of solvent removal methods include natural drying, ventilation drying, heating drying, and reduced pressure drying. The film is preferably dried such that the residual solvent in the protective layer is less than 1% by weight relative to the total mass of the polarizing film. Drying conditions such as drying temperature and drying time can be appropriately determined based on the composition of the protective layer forming composition and the materials constituting the polarizing film.

[0239] Preferably, the obtained coating is irradiated with active energy rays at room temperature, thereby polymerizing cationic or free radical polymeric compounds to create a protective layer. Examples of light sources for 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.

[0240] Regarding the irradiation energy of the active energy rays, it can be appropriately determined based on the type of cationic or free radical polymerizable compound contained in the composition for forming the protective layer, and preferably the irradiation intensity for the wavelength region effective for activation is 10 to 5000 mJ / cm. 2 The setting method is preferred, and more preferably, it is 100–2000 mJ / cm. 2 .

[0241] The aforementioned protective layer does not function as an adhesive layer. Therefore, in a preferred embodiment of the invention, during the curing of this protective layer, one side of the protective layer is adjacent to the polarizing film, but the other side is not adjacent to other films, etc. In this embodiment, the protective layer is the outermost layer of a polarizing plate that includes the polarizing film and the protective layer adjacent to the polarizing film.

[0242] From the viewpoint of suppressing the reflectivity of the obtained polarizer, the in-plane average refractive index of the protective layer is preferably 1.50 to 1.55, more preferably 1.50 to 1.53, and even more preferably 1.50 to 1.52. As a method for setting the in-plane average refractive index within the above range, for example, adjusting the composition of the protective layer forming composition can be cited.

[0243] The thickness of the protective layer is preferably 0.2 to 5 μm, more preferably 0.5 to 4 μm, even more preferably 0.7 to 3 μm, and even more preferably 1 to 2.5 μm. If the thickness of the protective layer is within the above range, it can function as a protective layer for the polarizing film, and can obtain sufficient strength to suppress the occurrence of warping over time and to prevent breakage when peeled from the substrate.

[0244] (Cure the resin layer)

[0245] The polarizing plate of the present invention may have an orientation layer sandwiched or not sandwiched on the opposite side of the surface of the horizontal polarizing film adjacent to the protective layer, and may also have a cured resin layer.

[0246] The cured resin layer is preferably a layer formed from a curable resin layer forming composition containing an active energy ray curable component. Examples of active energy ray curable components include cationic polymeric compounds and free radical polymeric compounds. The cationic polymeric compounds and free radical polymeric compounds described in the above-mentioned protective layer forming composition can be used as cationic polymeric compounds and free radical polymeric compounds that may be contained in the curable resin layer forming composition. The curable resin layer forming composition is preferably a cured layer containing a curable composition of a polyfunctional (meth)acrylate. Examples of polyfunctional (meth)acrylates include the polyfunctional (meth)acrylates described in the protective layer forming composition (2- to 8-functional (meth)acrylate monomers, 3-functional (meth)acrylate monomers), and the description of preferred polyfunctional (meth)acrylates that may be contained in the protective layer forming composition also applies.

[0247] From the viewpoint of thinning and suppressing the diffusion of dichroic pigments, the thickness of the cured resin layer is preferably 0.1 to 5 μm, more preferably 0.5 to 4 μm, even more preferably 1 to 3.5 μm, and even more preferably 1.5 to 3 μm.

[0248] The cured resin layer can be obtained, for example, by coating a curing resin layer forming composition onto the side of a resin film or the aforementioned polarizing film opposite to the protective layer, and then irradiating the coating film with active energy rays to cure the coating film. There are no particular limitations on the coating method for the curing resin layer forming composition; known methods such as spin coating, extrusion, gravure coating, die coating, rod coating, applicator coating, and flexographic printing can be used. In one embodiment of the present invention, it is preferable to use a film that has undergone a release treatment as the resin film, and then laminate the cured resin layer to form the polarizing film on the cured resin layer. In this embodiment, the final polarizing plate is preferably a polarizing plate that includes a peelable resin film on the cured resin layer, or a polarizing plate having a cured resin layer obtained after peeling off the peelable resin film as the outermost layer.

[0249] The active energy rays are appropriately selected based on the type of curable compound, the type of polymerization initiator, and their amounts. Specific examples include visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays, and gamma rays. Among these, ultraviolet light is preferred from the perspective of easy control of the polymerization reaction and the ability to use a widely used device in the field as a photopolymerization apparatus.

[0250] Examples of light sources that emit 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 that emit light in the wavelength range of 380–440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

[0251] The intensity of ultraviolet irradiation is appropriately determined based on the composition of the composition used to form the cured resin layer, and is not particularly limited, but is typically 10 to 3,000 mW / cm². 2 The intensity of ultraviolet irradiation is preferably within the wavelength range effective for activating the polymerization initiator. The irradiation time 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. One or more irradiations at this intensity result in a cumulative light intensity of 10 to 3,000 mJ / cm². 2 Preferably, it is 50–2,000 mJ / cm². 2 More preferably 100–1,000 mJ / cm 2 The thickness of the cured resin layer is not particularly limited; for example, it can be 0.1–5.0 μm.

[0252] (Resin layer)

[0253] The polarizing plate of the present invention also has a resin layer. The resin layer may be, for example, a layer comprising at least a resin film. The resin layer may be a single layer or multiple layers. As the resin film contained in the resin layer, resin film substrates conventionally known in the field of optical films may be used, for example. From the viewpoint of the lightfastness of the polarizing plate, it is preferable to design the resin layer in a manner that allows the optical properties of the laminate composed of layers closer to the observation side than the horizontal polarizing film in the polarizing plate of the present invention to be controlled within an appropriate range. Examples of resins constituting resin films include, for instance, polyolefin resins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; poly(meth)acrylic acid resins such as poly(meth)acrylate and poly(methyl)acrylate; cellulose ester resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; vinyl alcohol resins such as polyvinyl alcohol and polyvinyl acetate; polycarbonate resins; polystyrene resins; polyaryl ester resins; polysulfone resins; polyethersulfone resins; polyamide resins; polyimide resins; polyetherketone resins; polyphenylene sulfide resins; polyphenylene ether resins; and mixtures thereof. These resins can be used alone or in combination of two or more. Such resins can be used to form resin film substrates by solvent casting, melt extrusion, or other known methods. Furthermore, commercially available resins can be used as film substrates or resins constituting film substrates.

[0254] As the resin film, cellulose ester-based resin films, cyclic olefin-based resin films, polyester-based resin films, and poly(meth)acrylic acid-based resin films are preferred, with cyclic olefin-based resin films being more preferred. From the viewpoint of improving the lightfastness of the polarizing plate, these resin films facilitate the control of the optical properties of the laminate in the polarizing plate of the present invention, which consists of layers closer to the observation side than the horizontal polarizing film, within an appropriate range. Furthermore, in polarizing plates containing thin polarizing films, the generation of curling warping is easily suppressed. In addition, the use of cyclic olefin-based resin films can also be advantageous in terms of further improving the adhesion to adjacent layers.

[0255] Commercially available resin films can be used as the aforementioned resin film. Examples of commercially available resin films include Zeonor Film (registered trademark) manufactured by ZEON Corporation of Japan (e.g., Zeonor ZF, Zeonor ZF-U, Zeonor ZD-U).

[0256] Surface treatment can be applied to the resin film. Examples of surface treatment methods include treating the surface of the resin film with corona or plasma under a vacuum to atmospheric pressure atmosphere, laser treatment of the resin film surface, ozone treatment of the resin film surface, saponification treatment of the resin film surface, flame treatment of the resin film surface, coating the resin film surface with a coupling agent, primer treatment of the resin film surface, and graft polymerization, which involves attaching reactive monomers or reactive polymers to the surface of the resin film and then irradiating it with radiation, plasma, or ultraviolet light to cause a reaction.

[0257] The thickness of the resin film is preferably 5 to 50 μm, more preferably 8 to 45 μm, and even more preferably 10 to 40 μm. If the thickness of the resin film is within the above range, it can perform its function as a resin film and can also take into account the design of the layer thickness, etc., as a polarizing plate, and the process adaptability from polarizing plate manufacturing to actual use.

[0258] From the viewpoint of controlling the optical properties of a laminate consisting of layers closer to the observation side than the horizontal polarizing film in a polarizing plate to the aforementioned appropriate range, the resin layer preferably includes a light-absorbing layer, and more preferably includes two or more light-absorbing layers. The light-absorbing layer is preferably a layer formed by a light-absorbing layer forming composition containing a light-absorbing compound. The light-absorbing layer forming composition more preferably further includes at least one light-absorbing compound. The type and amount of the light-absorbing compound are not particularly limited as long as it can adjust the optical properties of the laminate consisting of layers closer to the observation side than the horizontal polarizing film in the polarizing plate of the present invention to an appropriate range; for example, compounds containing a partial cyanine (Japanese: メロシアニン) structure within the molecule are preferred. A compound containing a partial cyanine structure refers to a compound containing a partial structure shown as -(NC=CC=C)- within the molecule; examples include partial cyanine compounds, cyanine compounds, indole compounds, benzotriazole compounds, etc. The light-absorbing compound is more preferably a compound shown in formula (II) (hereinafter, sometimes referred to as compound (II)).

[0259] [Chemical Formula 13]

[0260]

[0261] In formula (II), R 31 and R 35 Each of the following groups independently represents a hydrogen atom, an alkyl group with 1 to 25 carbon atoms that may have substituents, an aralkyl group with 7 to 15 carbon atoms that may have substituents, an aryl group with 6 to 15 carbon atoms, or a heterocyclic group, wherein the -CH2- group contained in the alkyl or aralkyl group can be replaced by -NR. 1A -, -CO-, -SO2-, -O-, or -S- substitution.

[0262] R 1A It represents an alkyl group having 1 to 6 hydrogen atoms or carbon atoms.

[0263] R 32 R 33 and R 34 Each of the following can independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms that may have substituents, an aromatic hydrocarbon group that may have substituents, or an aromatic heterocyclic group that may have substituents, wherein the -CH2- contained in the alkyl group can be replaced by -NR 1B -, -CO-, -SO2-, -O-, or -S- substitution.

[0264] R 1B It represents an alkyl group having 1 to 6 hydrogen atoms or carbon atoms.

[0265] R 36 and R 37 Each independently represents a hydrogen atom, an alkyl group having 1 to 25 carbon atoms, or an electron-withdrawing group, or R36 and R 37 They can connect with each other to form a ring structure.

[0266] R 31 and R 32 They can be connected to form a ring structure, R 32 and R 33 They can be connected to form a ring structure, R 32 and R 34 They can be connected to form a ring structure, R 33 and R 36 They can connect to each other to form a ring structure.

[0267] In a preferred embodiment of the present invention, from the viewpoint of the lightfastness of the polarizing plate, it is preferable that the transmittance of the resin layer at a wavelength of 300 nm is 5% or less, at a wavelength of 380 nm is 10% or less, at a wavelength of 400 nm is 20% or less, and at a wavelength of 450 nm is 80% or more. Furthermore, from the viewpoint of the lightfastness of the polarizing plate, it is more preferable that the transmittance of the resin layer at a wavelength of 300 nm is 1% or less, even more preferably 0.8% or less, and particularly preferably 0.5% or less.

[0268] (Lamination layer a)

[0269] The polarizing plate of the present invention comprises, from the observation side, a resin layer, an adhesive layer a, a horizontal polarizing film and a protective layer, wherein the horizontal polarizing film is adjacent to the protective layer.

[0270] In one embodiment of the present invention, the polarizing plate of the present invention can be obtained by overlapping the above-described resin layer with a horizontal polarizing film and a protective layer, with an adhesive layer in between. In this embodiment, the resin film and the polarizing film are bonded together by an adhesive layer a, which serves as an adhesive layer or a bonding layer.

[0271] The bonding layer 'a' is not particularly limited as long as it functions as a layer that can bond the resin layer to the horizontal polarizing film, or to a cured resin layer disposed on the opposite side of the surface of the horizontal polarizing film adjacent to the aforementioned protective layer. It can be a layer formed from a known adhesive. The adhesive or bonding agent is not particularly limited; conventionally known adhesives and bonding agents can be used without particular restriction. Examples of adhesives include those with acrylic, rubber, urethane, silicone, or polyvinyl ether base polymers. Additionally, energy-curing adhesives and thermosetting adhesives can also be used. Examples of adhesives include active energy-curing adhesives, water-based adhesives, organic solvent-based adhesives, and solvent-free adhesives.

[0272] From the viewpoints of thinning the polarizing plate and suppressing curling, the thickness of the bonding layer a is preferably 1 to 10 μm, more preferably 1 to 8 μm, even more preferably 1 to 5 μm, and even more preferably 1.5 to 3 μm.

[0273] From the viewpoint of adjusting the transmittance of the laminate of the polarizing plate, which is composed of layers closer to the observation side than the horizontal polarizing film, at a specific wavelength to the range mentioned above, the average transmittance of the bonding layer a at a wavelength of 400 to 420 nm is preferably 99.5% or less, more preferably 98.0% or less, even more preferably 96.0% or less, and even more preferably 95.0% or less.

[0274] The polarizing plate of the present invention may also include other layers besides those described above, provided that the effect of the present invention is not affected. Examples of such other layers include adhesive layers, protective films, separators, antistatic layers, etc., for bonding with phase retardation layers, etc., as described later.

[0275] <Circular Polarizing Plate>

[0276] The polarizing plate of the present invention is suitable for use as a constituent material in liquid crystal display devices, organic EL display devices, etc., because it has excellent functions in suppressing curling and suppressing the diffusion of dichroic pigments from the polarizing film to other layers. The polarizing plate of the present invention can also be used as a circular polarizing plate in combination with a phase retardation film. In a preferred embodiment of the present invention, the polarizing plate can be used as a circular polarizing plate in which the polarizing plate and the phase retardation film are stacked together with an adhesive layer b in between, and the protective layer of the polarizing plate, the adhesive layer b, and the phase retardation film are sequentially adjacent. Therefore, the present invention also provides a circular polarizing plate, which is a circular polarizing plate in which the polarizing plate of the present invention and the phase retardation film are stacked together with an adhesive layer b in between, and the protective layer of the polarizing plate, the adhesive layer b, and the phase retardation film are sequentially adjacent.

[0277] (Phase difference film)

[0278] The retardation film contained in the circular polarizer is preferably composed of a polymer of a polymeric liquid crystal compound. If the retardation film is a cured layer (cured film) of a polymeric liquid crystal compound, a thinner circular polarizer can be formed compared to the case where the layer with the retardation is formed from a stretched film. However, since the retardation film is a thin film (e.g., 5 μm or less), it is prone to curling. In the optical laminate of the present invention, due to the presence of a specific protective layer, the occurrence of curling can be suppressed.

[0279] From the viewpoint that the aforementioned effects are easily made significant, in one embodiment of the present invention, the thickness of the retardation film is preferably 0.1–5 μm, more preferably 0.5–5 μm, further preferably 0.5–3 μm, and even more preferably 1–3 μm. It should be noted that, in the present invention, the retardation film is a film that displays a phase difference in the in-plane or thickness direction. It can be a single layer formed from a polymer of a polymeric liquid crystal compound, or, if the layer formed from the polymer exists adjacent to an alignment film used to form the layer, it can include the alignment film. When the retardation film includes the alignment film, the thickness of the retardation film does not include the thickness of the alignment film.

[0280] In this specification, there may be one retardation film or more than two retardation films. When there are more than two retardation films, the thickness of each retardation film may be appropriately determined according to the required optical characteristics of each retardation film, the composition of the optical laminate, the application, etc., and their thicknesses may be the same or different.

[0281] In order for the polarizer of the present invention to function as a circular polarizer, the circular polarizer preferably includes a phase difference film that satisfies the following formula (1).

[0282] 120nm≤Re(550)≤170nm (1)

[0283] [In the formula, Re(λ) represents the in-plane phase difference value of the phase difference film at wavelength λnm]

[0284] That is, in the case where the circular polarizer of the present invention contains only one phase difference film, the phase difference film preferably satisfies the above formula (1).

[0285] If the in-plane phase difference Re(550) of the retardation film is within the range of Equation (1), then the retardation film becomes a retardation film that functions as a 1 / 4 wavelength plate, and it is easy to improve the effect of front reflection tone (the effect of suppressing color) when the circular polarizer containing the retardation film is applied to organic EL display devices, etc. A further preferred range of the in-plane phase difference value is 130nm≤Re(550)≤150nm.

[0286] In addition to equation (4), the aforementioned phase difference film preferably also satisfies the following equations (2) and (3):

[0287] Re(450) / Re(550)≤1.00 (2)

[0288] 1.00≤Re(650) / Re(550) (3)

[0289] [In the formula, Re(λ) represents the in-plane phase difference value of the phase difference film at wavelength λnm].

[0290] When the retardation film satisfies equations (2) and (3), the retardation film exhibits so-called inverse wavelength dispersion, where the in-plane phase difference value at short wavelengths is smaller than the in-plane phase difference value at long wavelengths. Circular polarizers with such retardation films tend to exhibit excellent front-side color tone when assembled into organic EL display devices, etc. From the viewpoint that improving inverse wavelength dispersion can further enhance the effect of improving the reflected color tone in the front direction, Re(450) / Re(550) is preferably 0.70 or more, more preferably 0.78 or more, and preferably 0.92 or less, more preferably 0.90 or less, further preferably 0.87 or less, particularly preferably 0.86 or less, and even more particularly preferably 0.85 or less. Furthermore, Re(650) / Re(550) is preferably 1.01 or more, more preferably 1.02 or more.

[0291] The aforementioned in-plane phase difference value can be adjusted by the film thickness dA of the retardation film. The in-plane phase difference value is determined by the formula ReA(λ) = (nxA(λ) - nyA(λ)) × dA [where nxA(λ) represents the principal refractive index at wavelength λnm in the in-plane of the retardation film, nyA(λ) represents the refractive index at wavelength λnm in the same plane as nxA, orthogonal to the direction of nxA, and dA represents the film thickness of the retardation film]. Therefore, to obtain the desired in-plane phase difference value (ReA(λ): the in-plane phase difference value of the retardation film at wavelength λ (nm), the three-dimensional refractive index and film thickness dA can be adjusted.

[0292] The optical laminate of the present invention preferably includes a phase retardation film formed of a "horizontally oriented liquid crystal curing film", wherein the "horizontally oriented liquid crystal curing film" is formed by curing a polymeric liquid crystal compound in a state of horizontal orientation relative to the plane of the phase retardation film. In the case where the optical laminate of the present invention includes only one phase retardation film, the phase retardation film is usually a "horizontally oriented liquid crystal curing film", preferably satisfying the above formulas (1) to (3).

[0293] Examples of retardation films that can be included in the circular polarizer of the present invention include retardation films that function as positive C-plates (nx≈ny<nz) and retardation films that function as half-wavelength plates. The retardation film that functions as a positive C-plate is a "vertically oriented liquid crystal cured film" formed by curing a polymeric liquid crystal compound in a state where it is oriented perpendicularly to the plane of the retardation film. By combining a retardation film that functions as a quarter-wavelength plate and a retardation film that functions as a positive C-plate, when this circular polarizer is applied to an organic EL display device, an improvement in oblique reflection color tone can be expected in addition to an improvement in the front reflection color tone.

[0294] The polymeric liquid crystal compound capable of forming a retardation film in this invention can be appropriately selected from polymeric liquid crystal compounds conventionally known in the field of retardation films, depending on the desired optical properties. The polymeric liquid crystal compounds that can be used in this invention can be classified, for example, according to their shape, as rod-shaped (rod-shaped liquid crystal compounds) and disk-shaped (disc-shaped liquid crystal compounds, disc-shaped liquid crystal compounds), or any single liquid crystal compound can be used. Furthermore, two or more rod-shaped liquid crystal compounds, two or more disk-shaped liquid crystal compounds, or a mixture of rod-shaped and disk-shaped liquid crystal compounds can be used.

[0295] Polymerizable liquid crystal compounds are liquid crystal compounds having polymerizable groups. Examples of polymerizable liquid crystal compounds (cured products) obtained by polymerizing the polymerizable liquid crystal compound individually in a state of orientation along a specific direction include polymerizable liquid crystal compounds exhibiting positive wavelength dispersion and polymerizable liquid crystal compounds exhibiting reverse wavelength dispersion. In this invention, either one polymerizable liquid crystal compound may be used alone, or two polymerizable liquid crystal compounds may be used in combination.

[0296] In this invention, the polymeric groups in the polymeric liquid crystal compound forming the phase retardation film are preferably photopolymeric groups. Examples of photopolymeric groups include groups similar to those exemplified as polymeric groups that can be present in the polymeric liquid crystal compound forming the polarization film. The liquid crystal properties exhibited by the polymeric liquid crystal compound can be thermotropic or lyotropic, but thermotropic liquid crystals are preferred from the perspective of enabling dense film thickness control. Furthermore, the phase sequence structure in the thermotropic liquid crystal can be nematic liquid crystal, smectic liquid crystal, or discoid liquid crystal. Two or more polymeric liquid crystal compounds can be used alone or in combination.

[0297] As a polymeric liquid crystal compound (hereinafter also referred to as "polymeric liquid crystal compound (B)") that forms a phase difference film, from the viewpoint of endowing the phase difference properties shown in the above formulas (2) and (3), all compounds that satisfy the following (I) to (IV) can be cited.

[0298] (I) Compounds exhibiting thermotropic liquid crystal properties;

[0299] (II) The polymeric liquid crystal compound has π electrons in the long axis direction (a).

[0300] (III) It has π electrons in the direction intersecting the major axis direction (a) [intersecting direction (b)].

[0301] (IV) D(πa) and D(πb) are in a relationship of 0 ≤ [D(πa) / D(πb)] ≤ 1.

[0302] [That is, the π electron density in the cross direction (b) is greater than the π electron density in the major axis direction (a)]

[0303] The D(πa) is the π electron density in the long axis (a) of the polymeric liquid crystal compound, defined by the following equation (i), when the total number of π electrons present in the long axis direction (a) is set as N(πa) and the total number of molecular weights present in the long axis direction is set as N(Aa):

[0304] D(πa)=N(πa) / N(Aa) (i)

[0305] The D(πb) is the π electron density in the cross direction (b) of the polymeric liquid crystal compound, defined by the following formula (ii), when the total number of π electrons present in the cross direction (b) is set as N(πb) and the total number of molecular weights present in the cross direction (b) is set as N(Ab):

[0306] D(πb)=N(πb) / N(Ab) (ii).

[0307] It should be noted that, for all polymeric liquid crystal compounds (B) that satisfy (I) to (IV) above, a nematic phase or a smectic phase can be formed, for example, by heating to a temperature above the phase transition temperature. The nematic or smectic phase formed by the orientation of this polymeric liquid crystal compound is typically oriented such that the long axis directions of the polymeric liquid crystal compounds are parallel to each other, and this long axis direction becomes the orientation direction of the nematic or smectic phase.

[0308] Polymerizable liquid crystal compounds (B) possessing the above-mentioned properties generally exhibit reverse wavelength dispersion. Specifically, compounds that satisfy the properties described in (I) to (IV) above can be exemplified, for example, by compounds represented by the following formula (B1).

[0309] [Chemical Formula 14]

[0310]

[0311] The compound shown in formula (B1) above can be used alone or in combination of two or more.

[0312] In formula (B1), Ar represents a divalent group having an aromatic group that may have substituents. Examples of such aromatic groups include those 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 nitrogen, oxygen, or sulfur atoms. When Ar contains two or more aromatic groups, these two or more aromatic groups may be bonded to each other via single bonds, -CO-O-, -O-, or other divalent bonding groups.

[0313] In equation (B1), G1 and G 2 Each of these groups independently represents 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 may be replaced by a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 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 may be replaced by an oxygen atom, a sulfur atom, or a nitrogen atom.

[0314] In formula (B1), L 1 L 2 B 1 and B 2 Each is an independent single bond or a divalent linker.

[0315] In equation (B1), k and l independently represent integers from 0 to 3, satisfying the relationship 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.

[0316] In equation (B1), E 1 and E 2 Each alkyl group independently represents an alkyl group with 1 to 17 carbon atoms, more preferably an alkyl group with 4 to 12 carbon atoms. In addition, the hydrogen atoms contained in the alkyl group can be replaced by halogen atoms, and the -CH2- contained in the alkyl group can be replaced by -O-, -S-, or -C(=O)-.

[0317] In equation (X), P 1 and P 2 Each of the following groups represents a polymeric group or a hydrogen atom independently, with at least one being a polymeric group.

[0318] G 1 and G 2 Each of the following is preferably 1,4-phenylene diel that can be substituted with at least one substituent selected from halogen atoms and alkyl groups having 1 to 4 carbon atoms, or 1,4-cyclohexane diel that can be substituted with at least one substituent selected from halogen atoms and alkyl groups having 1 to 4 carbon atoms; more preferably methyl-substituted 1,4-phenylene diel, unsubstituted 1,4-phenylene diel, or unsubstituted 1,4-trans-cyclohexane diel; and particularly preferably unsubstituted 1,4-phenylene diel or unsubstituted 1,4-trans-cyclohexane diel.

[0319] 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 1or L 2 bonded G 1 and G 2 At least one of them is a divalent alicyclic hydrocarbon group.

[0320] 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 the following: 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-.

[0321] 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 the following: 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-.

[0322] 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, which is therefore preferred.

[0323] As P 1 or P 2 Examples of polymerizable groups include epoxy, vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, (meth)acryloyl, ethylene oxide, and oxetyl. Among these, (meth)acryloyl, vinyl, and vinyloxy are preferred, and (meth)acryloyl is more preferred.

[0324] Ar preferably has at least one 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.

[0325] In formula (B1), N represents the total number of π electrons possessed by the group represented by Ar. π The 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 36 or less, more preferably 32 or less, even more preferably 26 or less, and particularly preferably 24 or less.

[0326] Examples of aromatic groups contained in Ar include the following groups.

[0327] [Chemical Formula 15]

[0328]

[0329] In equations (Ar-1) to (Ar-23), The mark indicates the connection part, 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 alkylsulfinyl group (1-12 carbon atoms), an alkylsulfonyl group (1-12 carbon atoms), a carboxyl group, a fluoroalkyl group (1-12 carbon atoms), an alkoxy group (1-12 carbon atoms), an alkylthio 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.

[0330] In equations (Ar-1) to (Ar-23), 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.

[0331] In equations (Ar-1) to (Ar-23), J 1 and J 2 Each can be used to represent a carbon atom or a nitrogen atom independently.

[0332] In equations (Ar-1) to (Ar-23), Y 1 Y 2 and Y 3 Each can be independently represented as a substituted aromatic hydrocarbon group or an aromatic heterocyclic group.

[0333] In formula (Ar-1) to formula (Ar-23), 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.

[0334] As Y 1 Y2 and Y 3 The aromatic hydrocarbon group in the compound can include phenyl, naphthyl, anthraceneyl, phenanthryl, biphenyl, and other aromatic hydrocarbon groups with 6 to 20 carbon atoms, with phenyl and naphthyl being preferred, and phenyl being more preferred. As aromatic heterocyclic groups, can include furanyl, pyrroleyl, thiopheneyl, pyridyl, thiazolyl, benzothiazolyl, and other aromatic heterocyclic groups with 4 to 20 carbon atoms containing at least one heteroatom such as a nitrogen atom, oxygen atom, or sulfur atom, with furanyl, thiopheneyl, pyridyl, thiazolyl, and benzothiazolyl being preferred.

[0335] 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.

[0336] 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.

[0337] 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.

[0338] From the perspective of molecular stability, formulas (Ar-6) and (Ar-7) are preferred among formulas (Ar-1) to (Ar-23).

[0339] In formula (Ar-16) ~ (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 that Ar can possess, as described above, include pyrrole rings, imidazole 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.

[0340] The compound shown in formula (B1) can be manufactured, for example, according to the method described in Japanese Patent Application Publication No. 2010-31223.

[0341] Provided that the effects of the present invention are not impaired, the polymeric liquid crystal composition used to form the retardation film (hereinafter also referred to as the "composition for forming the retardation film") may also contain other polymeric liquid crystal compounds besides polymeric liquid crystal compound (B1). When the composition for forming the retardation film contains two or more polymeric liquid crystal compounds, from the viewpoint of obtaining a retardation film with excellent optical properties, it is preferable that at least one of them is polymeric liquid crystal compound (B1), and it is also possible that all of the components contained in the composition for forming the retardation film are polymeric liquid crystal compounds (B1).

[0342] The content of polymeric liquid crystal compound (B) in the phase retardation film forming composition is preferably 60 to 99.9% by mass, more preferably 70 to 99.9% by mass, and even more preferably 80 to 99% by mass, relative to the solid component of the polarization film forming composition. If the content of polymeric liquid crystal compound is within the above range, there is a tendency for the orientation of polymeric liquid crystal compound to become higher.

[0343] The phase retardation film forming composition may contain a polymerization initiator for initiating the polymerization reaction of a polymerizable liquid crystal compound. As the polymerization initiator, it can be appropriately selected from those conventionally used in the field; it can be a thermal polymerization initiator or a photopolymerization initiator. From the perspective of being able to initiate the polymerization reaction at lower temperatures, a photopolymerization initiator is preferred. Suitable examples are those previously exemplified as photopolymerization initiators that can be used in polarization film forming compositions. Furthermore, the phase retardation film forming composition may contain, as needed, a photosensitizer, a leveling agent, and additives, as exemplified as additives contained in polarization film forming compositions. As the photosensitizer and leveling agent, examples are those previously exemplified as photosensitizers and leveling agents that can be used in polarizer forming compositions.

[0344] The composition for forming a phase retardation film is prepared, for example, by mixing and stirring a polymerizable liquid crystal compound with a desired polymerization initiator, additives, etc. Furthermore, to improve coatability, a solvent can be added to the composition for forming the phase retardation film to adjust the viscosity. Examples of solvents include those exemplified above as solvents contained in compositions for forming polarizers.

[0345] A retardation film can be obtained by coating a retardation film forming composition onto a substrate or an alignment film, removing the solvent by drying, and then curing the polymeric liquid crystal compound in the resulting coating film in an aligned state. Examples of alignment films that are the same as those previously exemplified as alignment films used in the fabrication of polarizing films can be cited as examples.

[0346] The coating method for the composition used to form the phase difference film and the curing conditions using active energy rays are examples of methods that can be used in the preparation of polarization films.

[0347] When a retardation film is laminated onto a polarizer, it is preferable to laminate it such that the slow axis (optical axis) of the retardation film is substantially 45° to the absorption axis of the polarizer. By laminating the retardation film with its slow axis (optical axis) substantially 45° to the absorption axis of the polarizer, it functions as a circular polarizer. It should be noted that the substantially 45° is typically in the range of 45 ± 5°. The polarizer and the retardation film can be bonded, for example, by sandwiching an adhesive layer between them.

[0348] (Adhesive layer b)

[0349] In the circular polarizer of the present invention, the polarizer and the phase retardation film are stacked with an adhesive layer b in between. The adhesive layer b is a layer formed by an adhesive. This adhesive layer b is not particularly limited as long as it functions as a layer for bonding the polarizer, particularly a protective layer for the polarizer, to the phase retardation film; it can be a layer formed by a known adhesive. The adhesive or bonding agent is not particularly limited; conventionally known adhesives and bonding agents can be used without particular restriction. Examples of adhesives include those with acrylic, rubber, urethane, silicone, or polyvinyl ether base polymers. Additionally, energy-curing adhesives, thermosetting adhesives, etc., can also be used. Examples of adhesives include active energy-curing adhesives, water-based adhesives, organic solvent-based adhesives, and solvent-free adhesives.

[0350] From the viewpoint of making the circular polarizing plate thinner, the thickness of the bonding layer b is preferably 1 to 10 μm, and more preferably 3 to 8 μm.

[0351] The polarizing plate and circular polarizing plate of the present invention have excellent lightfastness and are suitable as components of various display devices. Furthermore, in a preferred embodiment of the present invention, curling is not easily generated, resulting in good processability when manufacturing image display devices, etc., incorporating the polarizing plate or circular polarizing plate.

[0352] A display device is a device having display elements, including light-emitting elements or light-emitting devices as light sources. Examples of display devices include liquid crystal displays, organic electroluminescent (EL) displays, inorganic electroluminescent (EL) displays, touch panel displays, electron emission displays (e.g., field emission displays (FED), surface field emission displays (SED)), electronic paper (display devices using electronic inks, electrophoretic elements, plasma displays), projection displays (e.g., grating light valve (GLV) displays, displays with digital micromirror devices (DMD)), and piezoelectric ceramic displays. Liquid crystal displays include any one of transmissive liquid crystal displays, transflective liquid crystal displays, reflective liquid crystal displays, direct-viewing liquid crystal displays, and projection liquid crystal displays. These display devices can be displays for two-dimensional images or stereoscopic displays for three-dimensional images. In particular, the polarizing plate and circular polarizing plate of the present invention can be suitably used in organic electroluminescent (EL) displays and inorganic electroluminescent (EL) displays, and can also be suitably used in liquid crystal displays and touch panel displays.

[0353] Example

[0354] The present invention will now be described in more detail with examples and comparative examples, but the invention is not limited to these examples. Unless otherwise specified, the amounts used, parts, and percentages of content are indicated on a mass basis.

[0355] <Manufacturing Example 1: Fabrication of Resin Layer A-1>

[0356] A cycloolefin-based film (Zeonor Film ZF (manufactured by ZEON Corporation of Japan)) was obtained, and one side of the Zeonor Film ZF was subjected to corona discharge treatment. The active energy ray-curable resin composition A1 described in paragraphs

[0151] to

[0153] and

[0155] of Japanese Patent Application Publication No. 2019-8292 was adjusted to an appropriate concentration and applied to the corona-discharge-treated surface using a rod coater. After drying, it was irradiated with ultraviolet light under a nitrogen atmosphere using an ultraviolet irradiation device with a conveyor belt (lamp: "H bulb" manufactured by Fusion UV Systems Co., Ltd.), thereby forming a light-absorbing layer A. The thickness of the light-absorbing layer A is 3 μm. The film with the light-absorbing layer A formed on one side of the Zeonor Film ZF obtained therein was used as resin layer A-1.

[0357] <Manufacturing Example 2: Fabrication of Resin Layer A-2>

[0358] A Zeonor Film ZF-U (manufactured by ZEON Corporation, Japan) with an ultraviolet absorbing layer (light absorption layer B) was used instead of Zeonor Film ZF. A light absorption layer A was formed on one side of the Zeonor Film ZF-U. Otherwise, a resin layer was obtained by the same method as described in Manufacturing Example 1. The thickness of the light absorption layer A was 3 μm. This film was used as resin layer A-2.

[0359] <Example 1>

[0360] 1. Fabrication of horizontal polarizing film

[0361] (1) Preparation of composition for forming horizontal polarizing film

[0362] The same method was used as described in paragraph

[0192] of Japanese Patent Application Publication No. 2020-56834 to obtain a composition for forming a horizontal polarizing film.

[0363] (2) Fabrication of horizontal polarizing film

[0364] The same method was performed as described in paragraphs

[0193] to

[0196] of Japanese Patent Application Publication No. 2020-56834, forming a cured resin layer (1.5 μm), a photo-alignment film, and a horizontal polarizing film (2.3 μm) on the demolded surface of the polyethylene terephthalate film that had undergone demolding treatment, thus obtaining a laminate X.

[0365] 2. Fabrication of Protective Layer B

[0366] On the surface opposite to the cured resin layer of the laminate X (horizontal polarizing film) obtained as described above, the composition for forming the protective layer B described below is applied using a bar coater to a cured thickness of 2.0 μm. After drying, the UVA region is irradiated with a cumulative light intensity of 600 mJ / cm² in a nitrogen atmosphere using a conveyor belt ultraviolet irradiation device (lamp: "H bulb" manufactured by Fusion UV Systems). 2 The ultraviolet light is used to form a protective layer B. Thus, a laminate Y-1 is obtained, which sequentially contains a PET release film, a cured resin layer, a photo-alignment film, a horizontal polarizing film, and a protective layer B.

[0367] (Preparation of the composition for forming protective layer B)

[0368] The following components were mixed and stirred at 23°C for 4 hours to obtain a composition for forming protective layer B.

[0369] • Multifunctional acrylate monomer: Dipentaerythritol hexaacrylate (trade name: NK ESTER A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd.): 50 parts by weight

[0370] • Carbamate acrylate polymer: Carbamate acrylate (trade name: EBECRYL 4858, manufactured by DAICEL-ALLNEX Co., Ltd., with 2 functional groups, a weight-average molecular weight (Mw) of 450, and 44.4 × 10⁻⁶ functional groups per unit molecular weight). -4 50 parts by weight

[0371] • Free radical polymerization initiator: 2-[4-(methylthio)benzoyl]-2-(4-morpholinyl)propane (trade name: Irgacure 907, manufactured by BASF): 3 parts by weight

[0372] Methyl ethyl ketone: 10 parts by weight

[0373] (In-plane average refractive index)

[0374] On one side of a stretched norbornene resin film (Zeonor Film, manufactured by ZEON Corporation, Japan), a protective layer B forming composition was applied using a bar coater (manufactured by Daiichi Rika Co., Ltd.) to achieve a thickness of approximately 30 μm after ultraviolet irradiation. The cumulative light intensity in the UVA region was 600 mJ / cm² under a nitrogen atmosphere using an ultraviolet irradiation device with a conveyor belt (lamp: "H bulb" manufactured by Fusion UV Systems). 2 Under ultraviolet light, the norbornene resin film was peeled off from the cured material, and the in-plane average refractive index (589 nm) of the cured layer was measured using a multi-wavelength Abbe refractometer (Atago Co., Ltd., DR-M2) at 25°C. The refractive indices of each protective layer obtained by measurement are recorded in Table 1.

[0375] 3. Fabrication of the phase retardation film

[0376] A horizontally oriented phase retardation film was fabricated by operating in the same manner as described in Example 1 (paragraphs

[0276] to

[0280] ) of Japanese Patent Application Publication No. 2022-176121.

[0377] 5. Fabrication of a circular polarizing plate

[0378] The protective layer B of the above-obtained laminate Y-1 is bonded to the coated side (liquid crystal layer side) of the horizontally aligned retardation film prepared above using an acrylic adhesive (pressure-sensitive adhesive manufactured by Lintec Corporation, 5 μm thick) to form laminate Z-1. During bonding, the relative angle between the slow axis of the retardation film and the absorption axis of the horizontal polarization film is 135 degrees. Then, after peeling off the PET film on the cured resin layer side of the above-obtained laminate Z-1, the cured resin layer and the surface opposite to the light absorption layer A of the above-obtained resin layer A-1 are bonded together using an acrylic adhesive to obtain a circular polarizing plate that sequentially includes resin layer A-1, bonding layer a (adhesive layer), cured resin layer, light alignment film, horizontal polarization film, protective layer B, bonding layer b (adhesive layer), and retardation film.

[0379] <Example 2>

[0380] As the resin layer, resin layer A-2 obtained in Manufacturing Example 2 was used instead of resin layer A-1 obtained in Manufacturing Example 1. Otherwise, a circular polarizing plate comprising resin layer A-2, bonding layer a (adhesive layer), cured resin layer, photo-alignment film, horizontal polarizing film, protective layer B, bonding layer b (adhesive layer), and phase difference film was obtained by means of the same method as described in Example 1.

[0381] <Example 3>

[0382] (Preparation of adhesive composition A)

[0383] Adhesive composition A was prepared by mixing the following ingredients.

[0384] • Neopentyl glycol diglycidyl ether (trade name: EX-211L, manufactured by Nagase ChemteX Co., Ltd.): 30 parts by weight

[0385] ·3-Ethyl-3{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane (trade name: OXT-221, manufactured by Toa Synthetic Co., Ltd.): 13 parts by weight

[0386] • Bisphenol A type epoxy resin (trade name: EP-4100E, ADEKA Co., Ltd., viscosity 13 Pa·s (temperature 25°C)): 45 parts by weight

[0387] • Aromatic oxobutane compound (trade name: TCM-104, manufactured by TRONLY): 12 parts by weight

[0388] • Cationic polymerization initiator (trade name: CPI-100_50% solution, manufactured by San-Apro Co., Ltd.): 5.5 parts by weight (actual solid content 2.75 parts by weight)

[0389] ·1,4-Diethoxynaphthalene: 1.2 parts by weight

[0390] ·9,10-Dibutoxyanthracene: 1.9 parts by weight

[0391] • Organosilicon-based leveling agent (trade name: KP-341, manufactured by Shin-Etsu Chemical Co., Ltd.): 0.25 parts by weight

[0392] It should be noted that the adhesive composition A prepared as described above was applied to the substrate using a rod coater to achieve a cured thickness of 2 μm. A UV irradiation device with a conveyor belt (using a "V-bulb" manufactured by Fusion UVSystems) was used, with a cumulative light intensity of 1600 mJ / cm² in the UV-V region. 2 After the adhesive was cured by irradiating visible light under a nitrogen atmosphere, the transmission spectrum of the adhesive layer (adhesive layer a) obtained by peeling it from the substrate was measured. The results showed that the average transmittance in the range of 400-420 nm was 94.70%.

[0393] (Fabrication of a circular polarizing plate)

[0394] A protective layer B forming composition was applied to the surface of the horizontal polarizing film of the laminate X obtained in the same manner as in Example 1, with a cured thickness of 1.0 μm. Otherwise, the protective layer B was formed on the surface of the horizontal polarizing film opposite to the cured resin layer using the same method as described in Example 1. Thus, a laminate Y-2 was obtained having a PET release film, a cured resin layer, a photoalignment film, a horizontal polarizing film, and a protective layer B in sequence. A laminate Z-2 was fabricated by bonding the protective layer B of the horizontal polarizing film with the phase retardation film to an acrylic adhesive using the same method as described in Example 1. Next, after peeling off the PET film from the cured resin layer side of the laminate Z-2, corona treatment was applied to the surfaces of the cured resin layer and the resin layer A-2 prepared in Manufacturing Example 2 opposite to the light-absorbing layer A. Adhesive composition A was applied to the corona-treated surface using a coating machine (a bar coater manufactured by Daiichi Rika Co., Ltd.), and bonding was performed using an attachment device ("LPA3301" manufactured by FUJIPLA Co., Ltd.). Using a conveyor belt-mounted ultraviolet irradiation device (using a "V bulb" manufactured by Fusion UV Systems), a cumulative light intensity of 1600 mJ / cm² in the wavelength region (UVV region) of 395–445 nm was irradiated from the substrate side of the retardation film. 2 Visible light is used to cure the adhesive, thereby obtaining a circular polarizing plate that sequentially includes a resin layer A-2, an adhesive layer a (adhesive layer), a cured resin layer, a light alignment film, a horizontal polarizing film, a protective layer B, an adhesive layer b (adhesive layer), and a phase difference film.

[0395] <Example 4>

[0396] When forming a protective layer B on the surface of the horizontal polarizing film of the laminate X, the composition for forming the protective layer B is applied so that the thickness after curing is 2.0 μm. Otherwise, a circular polarizing plate comprising a resin layer A-2, an adhesive layer a (adhesive layer), a cured resin layer, a photo-alignment film, a horizontal polarizing film, a protective layer B, an adhesive layer b (adhesive layer), and a phase difference film is obtained by means of the same method as described in Example 3.

[0397] <Example 5>

[0398] When forming a protective layer B on the surface of the horizontal polarizing film of the laminate X, the composition for forming the protective layer B is applied so that the thickness after curing is 5.0 μm. Otherwise, a circular polarizing plate comprising resin layer A-2, bonding layer a (adhesive layer), cured resin layer, photo-alignment film, horizontal polarizing film, protective layer B, bonding layer b (adhesive layer), and phase difference film is obtained by means of the same method as described in Example 3.

[0399] <Example 6>

[0400] (Creation of protective layer A)

[0401] On the surface of laminate X (horizontal polarizing film) opposite to the cured resin layer, the composition for forming protective layer A is applied using a bar coater to a cured thickness of 1.5 μm. The UVA region is then irradiated with a cumulative light intensity of 600 mJ / cm² in a nitrogen atmosphere using a conveyor belt-mounted ultraviolet irradiation device (lamp: "H bulb" manufactured by Fusion UV Systems). 2 The ultraviolet light emitted creates a protective layer A on the side of the horizontally polarized film opposite to the cured resin layer. Thus, a laminate Y-3 is obtained, consisting of a PET release film, a cured resin layer, a photo-alignment film, a horizontally polarized film, and a protective layer A.

[0402] (Preparation of the composition for forming protective layer A)

[0403] The following components were mixed and stirred at 23°C for 4 hours to obtain a composition for forming protective layer A.

[0404] Celloxide 2021P: 3,4-Epoxycyclohexanecarboxylic acid-3,4-epoxycyclohexylmethyl ester (manufactured by Daicel Chemical Co., Ltd.) 32.5 parts by weight

[0405] EHPE3150: 1,2-epoxy-4-(2-epoxyethylene)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (manufactured by Daicel Chemical Co., Ltd.) 17.5 parts by weight

[0406] • OXT-221: 50 parts by weight of bis(3-ethyl-3-oxetanebutylmethyl) ether (manufactured by Toa Synthetic Co., Ltd.)

[0407] • CPI-100P: 2.5 parts by weight of 50% solution of propylene carbonate of triarylsulfonium hexafluorophosphate (manufactured by San-Apro Co., Ltd.)

[0408] SH710: 0.25 parts by weight of silicone-based leveling agent (manufactured by Dow Corning Toray Co., Ltd.)

[0409] (Fabrication of a circular polarizing plate)

[0410] A circular polarizing plate comprising a resin layer A-2, an adhesive layer a, a cured resin layer, a photo-alignment film, a horizontal polarizing film, a protective layer A, an adhesive layer b, and a phase difference film was obtained by using the same method as described in Example 2.

[0411] <Example 7>

[0412] A circular polarizing plate comprising a resin layer A-2, an adhesive layer a (adhesive layer), a cured resin layer, a photo-alignment film, a horizontal polarizing film, a protective layer A, an adhesive layer b (adhesive layer), and a phase difference film was obtained by using the same method as described in Example 3.

[0413] <Comparative Example 1>

[0414] A circular polarizing plate comprising a resin layer (TAC), an adhesive layer a, a cured resin layer, a photo-alignment film, a horizontal polarizing film, a protective layer B, an adhesive layer b, and a phase retardation film was obtained by means of the same method described in Example 1, except that a triacetyl cellulose membrane (KC4UY, manufactured by Konica Minolta Co., Ltd.) was used instead of resin layer A-1.

[0415] <Optical property evaluation>

[0416] The transmitted light of the laminates consisting of layers closer to the observation side than the horizontal polarizing film obtained in the Examples and Comparative Examples was measured using a UV-Vis spectrophotometer. As the test sample, a laminate obtained by sequentially stacking layers closer to the observation side than the horizontal polarizing film was used. It should be noted that, for example, in the case of Example 1, the laminate of resin layer A-1, acrylic adhesive, cured resin layer, and photoalignment film corresponds to a laminate closer to the observation side than the horizontal polarizing film. In this example, a laminate obtained by separately stacking layers was used as the test sample, but the same result would occur if a laminate obtained by peeling off a layer closer to the observation side than the horizontal polarizing film from the circular polarizing plate was used as the test sample. The results are shown in Table 1.

[0417] The evaluation methods for optical properties are as follows.

[0418] (a) Comparative Example 1, Examples 1, 2, and 6

[0419] The resin layer was bonded to the glass using an acrylic adhesive (adhesive layer a), and the transmittance was measured.

[0420] (b) Examples 3, 4, 5, and 7

[0421] Adhesive composition A was coated onto a resin layer and cured to obtain a laminate P. The adhesive layer (adhesive layer a) of laminate P was bonded to glass using an adhesive to obtain sample Q. Separately, sample R was prepared by bonding only the adhesive to the glass. The transmittance of both sample Q and sample R was measured. Then, the transmittance of sample R was subtracted from the transmittance of sample Q to obtain the transmittance of the laminate located closer to the observation side than the horizontal polarizing film.

[0422] It should be noted that in this embodiment and comparative example, since the cured resin layer and the alignment layer do not contain materials that change the transmittance value, the transmittance of the laminate of the resin layer and the bonding layer a is measured. The result obtained is the same as the value measured using a laminate of resin layer / bonding layer a / cured resin layer / alignment layer, which is a layer composed of layers closer to the observation side than the horizontal polarizing film, acting as a polarizing plate.

[0423] <Lightfastness Evaluation>

[0424] The release film was peeled off from the phase retardation film side of the circular polarizer obtained in the examples and comparative examples, and then bonded to glass using an acrylic adhesive, thereby producing a sample for evaluating lightfastness testing. In a xenon lightfastness testing machine (equipment name: Atlas Ci4400, manufactured by DJK Corporation), the film (resin layer) with the ultraviolet absorption layer of the circular polarizer was used as the light source side, and the output power at a wavelength of 420 nm was set to 2.4 W / m. 2Under the conditions, the circular polarizer was immersed for 80 hours and 240 hours.

[0425] For samples that underwent lightfastness testing using the above method, the glass surface was positioned on the light source side and placed on a backlight. A linear polarizer was set to an orthogonal Nicol prism configuration. The appearance was visually observed from the front of the sample, and the lightfastness was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[0426] (Evaluation Criteria)

[0427] A: In either case after 80 hours or 240 hours, almost no light leakage was observed on the front side of the sample.

[0428] B: Almost no light leakage was observed after 80 hours, but slight light leakage was observed at the end after 240 hours.

[0429] C: Slight light leakage was observed at the end after 80 hours, and significant light leakage was observed after 240 hours.

[0430] D: Obvious light leakage was observed at the end after 80 hours.

[0431] <Curly Evaluation>

[0432] The circular polarizer prepared by the above method was cut into 8cm × 8cm pieces with the absorption axis at 45°. The release film was peeled off from the phase retardation film side, thus preparing a sample for curl evaluation. The sample was placed on a flat stage with the phase retardation film side up, and the curl values ​​at the four corners were measured. The sum of these values ​​was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[0433] (Evaluation Criteria)

[0434] A: Less than 20mm

[0435] B: 20mm or more but less than 35mm

[0436] C: 35mm or more and less than 60mm

[0437] D: 60mm and above

[0438] [Table 1]

[0439]

Claims

1. A polarizing plate, comprising, from the observation side, a resin layer, an adhesive layer a, a horizontal polarizing film, and a protective layer in sequence. The horizontal polarizing film, adjacent to the protective layer, is composed of a cured polymeric liquid crystal composition containing a polymeric liquid crystal compound and a dichroic pigment, and has a thickness of 0.1 μm to 5 μm. The protective layer is a cured layer of a curable composition containing a polymeric compound. The polarizing plate, consisting of a layer on the observation side closer to the horizontal polarizing film, has a transmittance of less than 10% at a wavelength of 380 nm, less than 20% at a wavelength of 400 nm, and more than 80% at a wavelength of 450 nm.

2. The polarizing plate according to claim 1, wherein, On the opposite side of the surface of the horizontal polarizing film adjacent to the protective layer, an alignment layer, with or without an alignment layer, is also provided, along with a cured resin layer.

3. The polarizing plate according to claim 2, wherein, The cured resin layer is a cured layer of a curable composition containing polyfunctional (meth)acrylate and has a thickness of 0.1 μm to 5 μm.

4. The polarizing plate according to claim 1 or 2, wherein, The polarizing plate, consisting of a layer on the observation side that is closer to the horizontal polarizing film than the polarizing film, has a transmittance of less than 5% at a wavelength of 300 nm.

5. The polarizing plate according to claim 1 or 2, wherein, The resin layer has a transmittance of less than 5% at a wavelength of 300nm, less than 10% at a wavelength of 380nm, less than 20% at a wavelength of 400nm, and more than 80% at a wavelength of 450nm.

6. The polarizing plate according to claim 1 or 2, wherein, The polarizing plate, consisting of a layer on the observation side that is closer to the horizontal polarizing film, has an average transmittance of less than 30% at wavelengths of 400 nm to 420 nm.

7. The polarizing plate according to claim 1 or 2, wherein, The dichroic pigments include pigments that have absorption at wavelengths below 450 nm.

8. The polarizing plate according to claim 1 or 2, wherein, The protective layer is a cured layer of a curable composition containing a cationic polymeric compound.

9. A circular polarizing plate, which is a circular polarizing plate formed by stacking a polarizing plate as described in claim 1 or 2 and a phase difference film with an adhesive layer b sandwiched between them, wherein the protective layer contained in the polarizing plate, the adhesive layer b and the phase difference film are sequentially adjacent to each other.

10. The circular polarizing plate according to claim 9, wherein, The phase retardation film is composed of a cured product of a curable composition containing a polymeric liquid crystal compound.

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