Optical film, circularly polarizing plate, image display device

Abstract

This invention provides an optical film, a circular polarizer, and an image display device that can suppress crack formation in the resulting film during die-cutting. One optical film comprises: a stretched resin film; and a liquid crystal layer formed by fixing a liquid crystal compound twisted and oriented along a helical axis extending in the thickness direction, wherein the δa value calculated using the three-dimensional solubility parameter of the resin in the stretched resin film is 8.0 MPa. 1 / 2 The liquid crystal layer comprises a cured polyfunctional compound having two or more polymerizable groups per molecule. The absolute value of the difference between the δa value calculated using the three-dimensional solubility parameters of the polyfunctional compound and the δa value calculated using the three-dimensional solubility parameters of the resin is 4.0 MPa. 1 / 2 the following.

Description

Technical Field

[0001] This invention relates to optical films, circular polarizers, and image display devices. Background Technology

[0002] Liquid crystal layers with anisotropic refractive index are used in various applications such as anti-reflective films for display devices and optical compensation films for liquid crystal display devices.

[0003] For example, Patent Document 1 discloses a method for manufacturing a multilayer film, which includes an optical film comprising a stretched resin film and an optically anisotropic layer formed by fixing a uniformly oriented liquid crystal compound.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-160465

[0005] The optical film is formed according to its intended use. The optical film is punched and adjusted to a specified size. Preferably, no cracks are generated in the film obtained through this punching process. Particularly preferred is that no cracks are generated at the periphery of the resulting film.

[0006] The inventors have discovered that cracks are generated in the resulting film when the optical film described in Patent Document 1 is punched. Summary of the Invention

[0007] In view of the above, the objective of the present invention is to provide an optical film that can suppress the formation of cracks in the resulting film during the die-cutting process.

[0008] Furthermore, the present invention also aims to provide a circular polarizer and an image display device.

[0009] Based on in-depth research into the problems of the prior art, the inventors discovered that the above-mentioned issues can be solved through the following structure.

[0010] (1) An optical film having:

[0011] Stretched resin film; and

[0012] A liquid crystal layer is formed by fixing a liquid crystal compound that is twisted and oriented along a helical axis extending in the thickness direction.

[0013] The δa value calculated using the three-dimensional solubility parameter of the resin in the stretched resin film is 8.0 MPa. 1 / 2 The following describes a liquid crystal layer comprising a cured product of a multifunctional compound having two or more polymerizable groups in one molecule.

[0014] The absolute value of the difference between the δa value calculated using the three-dimensional solubility parameters of the multifunctional compound and the δa value calculated using the three-dimensional solubility parameters of the resin is 4.0 MPa. 1 / 2 the following.

[0015] (2) According to the optical film of (1), the curings of the multifunctional compound are more present on the surface of the stretching resin film side than on the surface of the liquid crystal layer opposite to the stretching resin film side.

[0016] (3) The optical film according to (1) or (2), wherein a mixture of a cured material containing a multifunctional compound and a resin constituting the stretched resin film is further provided between the stretched resin film and the liquid crystal layer.

[0017] (4) The optical film according to (3), wherein the thickness of the hybrid layer is 5 to 50 nm.

[0018] (5) The optical film according to any one of (1) to (4), wherein the stretched resin film comprises a resin selected from the group consisting of cyclic olefin polymers and polystyrene.

[0019] (6) The optical film according to any one of (1) to (5), wherein the stretched resin film comprises a cyclic olefin polymer.

[0020] The multifunctional compound is non-liquid crystal and has a hydrocarbon group with 5 or more carbon atoms.

[0021] (7) The optical film according to (6), wherein the multifunctional compound has at least one group selected from the group consisting of a straight-chain hydrocarbon group having 8 or more carbon atoms and a cyclic hydrocarbon group having 5 or more carbon atoms.

[0022] (8) The optical film according to any one of (1) to (5), wherein the stretched resin film comprises polystyrene.

[0023] The multifunctional compound is non-liquid crystal and has more than one aromatic ring.

[0024] (9) The optical film according to any one of (1) to (8), wherein the weight-average molecular weight of the multifunctional compound is 10,000 or more.

[0025] (10) The optical film according to any one of (1) to (9), wherein the stretched resin film has an in-plane retardation of 100 to 250 nm at a wavelength of 550 nm.

[0026] (11) The optical film according to any one of (1) to (10), wherein the twist angle of the liquid crystal compound is 60 to 100°.

[0027] The product of the refractive index anisotropy Δn of the liquid crystal layer at a wavelength of 550 nm and the thickness d of the liquid crystal layer, Δnd, is 100–250 nm.

[0028] (12) A circular polarizer comprising the optical film described in any one of (1) to (11).

[0029] (13) An image display device comprising the optical film described in any one of (1) to (11).

[0030] Invention Effects

[0031] According to the present invention, it is possible to provide an optical film that can suppress the formation of cracks in the resulting film during the punching process.

[0032] Furthermore, according to the present invention, a circular polarizer and an image display device can also be provided. Detailed Implementation

[0033] The present invention will now be described in detail.

[0034] In addition, in this specification, the numerical range indicated by “~” refers to the range included by taking the values ​​recorded before and after “~” as the lower limit and upper limit values.

[0035] Furthermore, unless otherwise specified, the slow axis and fast axis are defined at a wavelength of 550 nm. That is, unless otherwise specified, for example, the direction of the slow axis refers to the direction of the slow axis at a wavelength of 550 nm.

[0036] In this invention, Re(λ) and Rth(λ) represent the in-plane delay and the thickness direction delay at wavelength λ, respectively. Unless otherwise specified, wavelength λ is 550 nm.

[0037] In this invention, Re(λ) and Rth(λ) are values ​​measured at wavelength λ using an AxoScan OPMF-1 (manufactured by Opto Science, Inc.). The values ​​are calculated by inputting the average refractive index ((nx+ny+nz) / 3) and film thickness (d(μm)) into the AxoScan.

[0038] Slow axis direction (°)

[0039] Re(λ)=R0(λ)

[0040] Rth(λ)=((nx+ny) / 2-nz)×d.

[0041] Additionally, R0(λ) is shown as a value calculated using AxoScan OPMF-1, representing Re(λ).

[0042] In this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by ATAGO CO.,LTD.) and a sodium lamp (λ = 589 nm) as the light source. Furthermore, when measuring wavelength dependence, measurements can be performed using a multi-wavelength Abbe refractometer DR-M2 (manufactured by ATAGO CO.,LTD.) combined with an interference filter.

[0043] Furthermore, values ​​from the Polymer Handbook (JOHN WILEY & SONS, INC) and various optical film catalogs can be used. The average refractive index values ​​of the main optical films are exemplified below: cellulose acylate (1.48), cyclic olefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0044] In addition, in this specification, "visible light" refers to light with a wavelength of 400 to 700 nm. Furthermore, "ultraviolet light" refers to light with a wavelength of 10 nm or more but less than 400 nm.

[0045] Furthermore, in this specification, the terms relating to angles (e.g., "orthogonal", "parallel", etc.) include the range of errors permissible in the technical field to which this invention pertains. For example, it may mean within a tight angle of ±5°, and the error from the tight angle is preferably within a range of ±3°.

[0046] The bonding direction of the divalent group (e.g., -COO-) described in this specification is not particularly limited. For example, if L in XLY is -COO-, and the position bonded to the X side is set as *1 and the position bonded to the Y side is set as *2, then L can be *1-O-CO-*2 or *1-CO-O-*2.

[0047] As a characteristic feature of the optical film of the present invention, one can cite the use of a liquid crystal layer formed by fixing a twisted and oriented liquid crystal compound and a cured product containing a multifunctional compound, wherein the absolute value of the difference between the δa value calculated using the three-dimensional solubility parameter of the multifunctional compound and the δa value calculated using the three-dimensional solubility parameter of the resin contained in the stretched resin film is within a specified range.

[0048] The inventors investigated the reasons why cracks are easily generated in films obtained by punching the optical film disclosed in Patent Document 1. They found that in optical films comprising a stretched resin film and a liquid crystal layer formed by fixing a uniformly oriented liquid crystal compound, cracks are easily generated along that direction, especially when the stretching direction of the stretched resin film is parallel to the orientation direction of the uniform orientation.

[0049] Therefore, in this invention, it was first discovered that if a liquid crystal layer formed by fixing a twisted and oriented liquid crystal compound is used as the liquid crystal layer, crack generation can be suppressed even when the stretching direction of the stretched resin film is arranged parallel to the orientation direction of the liquid crystal compound on one surface of the liquid crystal layer.

[0050] It was also found that other major causes of cracking were insufficient adhesion between the stretched resin film and the liquid crystal layer.

[0051] Therefore, in this invention, it has been found that by using a cured product containing a multifunctional compound in the liquid crystal layer, the adhesion between the stretched resin film and the liquid crystal layer is improved, resulting in the suppression of crack formation. In this invention, the absolute value of the difference between the δa value of the multifunctional compound and the δa value calculated using the three-dimensional solubility parameter of the resin contained in the stretched resin film is within a specified range.

[0052] The optical film of the present invention comprises: a stretched resin film; and a liquid crystal layer, formed by fixing a liquid crystal compound twisted and oriented along a helical axis extending in the thickness direction, wherein the δa value calculated using the three-dimensional solubility parameter of the resin in the stretched resin film is 8.0 MPa. 1 / 2 The liquid crystal layer comprises a cured polyfunctional compound having two or more polymerizable groups per molecule. The absolute value of the difference between the δa value calculated using the three-dimensional solubility parameters of the polyfunctional compound and the δa value calculated using the three-dimensional solubility parameters of the resin is 4.0 MPa. 1 / 2 the following.

[0053] The following is a detailed description of each component contained in the optical film.

[0054] <Stretched Resin Film>

[0055] The optical film of the present invention comprises a stretched resin film.

[0056] Stretched resin film refers to a resin film that has undergone stretching treatment. It can be a uniaxially stretched resin film or a biaxially stretched resin film.

[0057] There are no particular restrictions on the resins contained in the stretched resin film; examples include acrylic resins, styrene-based resins, cycloolefin resins, polyester resins, polycarbonate resins, and cellulose derivatives.

[0058] Furthermore, resins are classified into resins with positive intrinsic birefringence and resins with negative intrinsic birefringence based on their differences in optical performance during stretching. The resin contained in the stretched resin film used in this invention can be either a resin with positive intrinsic birefringence or a resin with negative intrinsic birefringence.

[0059] Examples of resins with inherently positive birefringence include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyarylene sulfides such as polyphenylene sulfide; polycarbonate; polyallyl sulfone; polyvinyl chloride; cyclic olefin polymers such as norbornene polymers; and rod-shaped liquid crystal polymers.

[0060] Furthermore, examples of resins with inherently negative birefringence include homopolymers of styrene or styrene derivatives (e.g., polystyrene, fluorinated polystyrene) and polystyrene-based polymers containing copolymers of styrene or styrene derivatives with any monomer; polyacrylonitrile polymers; and (meth)acrylic polymers such as polymethyl methacrylate.

[0061] From the viewpoint of optical properties, cyclic olefin polymers or polystyrene are preferred as the resin contained in the stretched resin film.

[0062] The δa value calculated using the three-dimensional solubility parameters of the resin contained in the stretched resin film is 8.0 MPa. 1 / 2 The following is a description of the pressure at which the optical film is die-cut, from the viewpoint of further suppressing crack formation in the resulting film (hereinafter also referred to as "from the viewpoint of better performance of the present invention"), is preferably 7.0 MPa. 1 / 2 Hereinafter, 6.0 MPa is more preferred. 1 / 2 The lower limit is not specifically limited, but is mostly 2.0 MPa. 1 / 2 The above values ​​are mostly 3.0 MPa. 1 / 2 That's all. As mentioned above, the unit of δa is (MPa). 1 / 2 .

[0063] In this specification, the δa value refers to the non-dispersive component of the SP value calculated by Hoy et al. (refer to VAN KREVELEN, DW, "Properties of Polymers" (ED.3), ELSEVIER, 1990).

[0064] That is, the δa value can be calculated using the three-dimensional solubility parameters (δd, δp, δh) obtained by Hoy et al., and by the following equation (X).

[0065] δa=(δp 2 +δh 2 ) 0.5 Formula (X)

[0066] According to the method of Hoy et al., the values ​​of δd, δp and δh can be calculated based on the chemical structural formula of the compound to be obtained.

[0067] In addition, in the case of polymers containing multiple repeating units, the three-dimensional solubility parameters (δd, δp, δh) of the polymer can be calculated by multiplying the three-dimensional solubility parameters (δd, δp, δh) of each repeating unit by the volume fraction of each repeating unit and summing them. By substituting these parameters into the above equation (X), the value of δa of the polymer can be obtained.

[0068] In this specification, the three-dimensional solubility parameters of each material can be obtained using the software HSP (Hansen Solubility Parameters in Practice: Windows software for efficient processing of HSP) (ver. 5.1.08) developed by Hansen et al.

[0069] There is no particular limitation on the in-plane retardation of the stretched resin film at a wavelength of 550 nm, but from the viewpoint of superior optical properties of the optical film, 100 to 250 nm is preferred, and 150 to 200 nm is more preferred.

[0070] The surface of the stretched resin film (particularly the surface of the side of the liquid crystal layer to be laminated) can be treated. Examples of surface treatments include corona treatment and plasma treatment. By performing the above surface treatments, the stretched resin film and the liquid crystal layer can be easily bonded together, and crack resistance becomes advantageous. The conditions of the surface treatment can be adjusted appropriately.

[0071] There is no particular limitation on the thickness of the stretched resin film, but from the viewpoint of thinness, it is preferably 200 μm or less, more preferably 20 to 150 μm, and even more preferably 40 to 100 μm.

[0072] Furthermore, in this specification, the thickness of the stretched resin film refers to the average thickness of the stretched resin film. This average thickness is calculated by measuring the thickness of the stretched resin film at any five or more locations and then taking the arithmetic mean of these measurements.

[0073] There are no particular restrictions on the manufacturing method of stretched resin film. For example, a known stretching machine such as a tenter frame can be used to stretch an unstretched resin film.

[0074] As a stretching method, known methods include longitudinal uniaxial stretching, transverse uniaxial stretching, or a combination of both, such as simultaneous biaxial stretching or successive biaxial stretching.

[0075] Furthermore, commercially available products can also be used as stretch resin films.

[0076] <Liquid Crystal Layer>

[0077] The optical film of the present invention comprises a liquid crystal layer formed by fixing a liquid crystal compound twisted and oriented along a helical axis extending in the thickness direction.

[0078] The liquid crystal layer is preferably a layer formed by fixing a chiral nematic phase having a so-called helical structure. Furthermore, when forming the liquid crystal layer, it is preferable to use at least a liquid crystal compound and a chiral reagent described later.

[0079] Furthermore, the "fixed" state refers to the state in which the orientation of the liquid crystal compound is maintained. Specifically, the preferred state is one in which the layer does not flow under normal conditions of 0 to 50°C, or more stringent conditions of -30 to 70°C, and its orientation morphology does not change due to external fields or forces, thus stably and continuously maintaining a fixed orientation morphology.

[0080] There are no particular limitations on the twist angle of the liquid crystal compound (the twist angle of the orientation direction of the liquid crystal compound), and it is mostly greater than 0° and less than 360°. From the viewpoint of superior optical properties of the optical film, it is preferred to be 60 to 100°, and more preferably 70 to 90°.

[0081] In addition, regarding the measurement method of the torsion angle, the AxoScan (polarimeter) device from Axometrics was used, and the device analysis software from Axometrics was used for measurement.

[0082] Furthermore, liquid crystal compound twisting orientation refers to the twisting of the liquid crystal compound from one main surface of the liquid crystal layer to another, with the thickness direction of the liquid crystal layer as the axis. Meanwhile, the orientation direction (in-plane slow axis direction) of the liquid crystal compound varies depending on its position along the thickness direction of the liquid crystal layer.

[0083] There is no particular limitation on the value of the product Δnd of the refractive index anisotropy Δn of the liquid crystal layer and the thickness d of the liquid crystal layer, which is measured at a wavelength of 550 nm. However, from the viewpoint of superior optical properties of the optical film, it is preferred to be 100 to 250 nm, and more preferably 150 to 200 nm.

[0084] In addition, refractive index anisotropy Δn refers to the refractive index anisotropy of the liquid crystal layer.

[0085] Regarding the measurement method of Δnd mentioned above, the AxoScan (polarimeter) device from Axometrics Corporation was used, and the device analysis software from Axometrics Corporation was used for measurement.

[0086] There are no particular restrictions on the types of liquid crystal compounds used to form liquid crystal layers; examples include rod-shaped liquid crystal compounds and disc-shaped liquid crystal compounds (disc-shaped liquid crystal compounds).

[0087] As a rod-shaped liquid crystal compound, for example, the compounds described in claim 1 of Japanese Patent Application Publication No. 11-513019 and paragraphs 0026 to 0098 of Japanese Patent Application Publication No. 2005-289980 may be preferred.

[0088] As a disc-shaped liquid crystal compound, for example, the compounds described in paragraphs 0020 to 0067 of Japanese Patent Application Publication No. 2007-108732 and paragraphs 0013 to 0108 of Japanese Patent Application Publication No. 2010-244038 may be preferred.

[0089] Liquid crystal compounds may have polymerizable groups. There are no particular limitations on the type of polymerizable groups, but functional groups capable of undergoing addition polymerization are preferred, polymerizable olefinic unsaturated groups or cyclopolymerizable groups are more preferred, and (meth)acryloyl, vinyl, styrene or allyl are even more preferred.

[0090] The liquid crystal layer is preferably a layer formed by polymerization of a liquid crystal compound having polymerizable groups. More specifically, a layer formed by polymerization of a liquid crystal compound having polymerizable groups in a twisted orientation is more preferably a layer formed by polymerization of such a compound.

[0091] Liquid crystal layers are cured products of multifunctional compounds having two or more polymerizable groups in one molecule.

[0092] In cases where a multifunctional compound has two or more polymerizable groups in one molecule and is a compound other than a polymer having multiple repeating units, from the viewpoint of achieving better results in this invention, the number of polymerizable groups in the multifunctional compound is preferably 2 to 12, more preferably 2 to 9.

[0093] There are no particular limitations on the types of polymerizable groups contained in the multifunctional compound; examples of polymerizable groups that the liquid crystal compound may possess can be cited. Among these, polymerizable olefinic unsaturated groups are preferred, and (meth)acryloyl, vinyl, styrene, or allyl groups are more preferred.

[0094] The absolute value of the difference between the δa value calculated using the three-dimensional solubility parameters of the multifunctional compound and the δa value calculated using the three-dimensional solubility parameters of the resin contained in the stretched resin film is 4.0 MPa. 1 / 2 From the viewpoint of achieving better results with the present invention, 3.0 MPa is preferred. 1 / 2 Hereinafter, 2.0 MPa is more preferred. 1 / 2 The following is a lower limit; there is no particular limitation, but 0 MPa is preferred. 1 / 2 .

[0095] The δa value calculated using the three-dimensional solubility parameter of the multifunctional compound is not particularly limited as long as the above relationship is satisfied. However, from the viewpoint of achieving better results in this invention, a value of 0 to 10 MPa is preferred. 1 / 2 More preferably 4-8 MPa 1 / 2 .

[0096] There are no particular restrictions on the placement of the cured multifunctional compound in the liquid crystal layer, but from the viewpoint of achieving better results, it is preferable that the cured multifunctional compound is present more on the surface of the stretched resin film side than on the surface of the liquid crystal layer opposite to the stretched resin film side.

[0097] The placement of cured multifunctional compounds in the liquid crystal layer can be determined using time-of-flight secondary ion mass spectrometry (TOF-SIMS). More specifically, while irradiating the liquid crystal layer from the surface opposite to the stretched resin film side towards the stretched resin film side, the composition along the depth direction of the liquid crystal layer is analyzed using TOF-SIMS. The distribution of secondary ion intensities from the cured multifunctional compounds along the depth direction is obtained, and the secondary ion intensities from the cured multifunctional compounds on the surface opposite to the stretched resin film side of the liquid crystal layer are compared with those on the surface opposite to the stretched resin film side. If the secondary ion intensity of the cured multifunctional compounds on the surface of the stretched resin film side of the liquid crystal layer is greater than that on the surface opposite to the stretched resin film side, it can be said that the cured multifunctional compounds are present more abundantly on the surface of the stretched resin film side of the liquid crystal layer than on the surface opposite to the stretched resin film side.

[0098] The multifunctional compound is preferably non-liquid crystal osmotic. That is, the multifunctional compound is preferably not a liquid crystal compound. Non-liquid crystal osmotic means that it does not exhibit liquid crystal properties.

[0099] In the case where the stretched resin film contains a cyclic olefin polymer, from the viewpoint of achieving better results according to the present invention, the multifunctional compound preferably has a hydrocarbon group having 5 or more carbon atoms, and more preferably has a group having at least one selected from the group consisting of a straight-chain hydrocarbon group having 8 or more carbon atoms and a cyclic hydrocarbon group having 5 or more carbon atoms.

[0100] The hydrocarbon group having 5 or more carbon atoms can be a monovalent group or a divalent or more group. Preferably, the hydrocarbon group having 5 or more carbon atoms contains 5 to 20 carbon atoms, more preferably 5 to 15. The hydrocarbon group having 5 or more carbon atoms can be linear, branched, or cyclic. The hydrocarbon group having 5 or more carbon atoms can be an aliphatic group or an aromatic group.

[0101] The aforementioned straight-chain hydrocarbon group with 8 or more carbon atoms can be a monovalent group or a divalent or more group. The number of carbon atoms contained in the straight-chain hydrocarbon group with 8 or more carbon atoms is preferably 8 to 20, more preferably 8 to 15.

[0102] The cyclic hydrocarbon group having 5 or more carbon atoms can be a monovalent group or a divalent or more group. The number of carbon atoms in the cyclic hydrocarbon group having 5 or more carbon atoms is preferably 5 to 20, more preferably 5 to 10. The cyclic hydrocarbon group having 5 or more carbon atoms can be an aliphatic cyclic hydrocarbon group or an aromatic cyclic hydrocarbon group. The cyclic hydrocarbon group having 5 or more carbon atoms can be a monocyclic structure or a fused ring structure.

[0103] In the case where the stretched resin film contains polystyrene, from the viewpoint of achieving better results in this invention, the multifunctional compound preferably has one or more aromatic rings.

[0104] The number of aromatic rings contained in the polyfunctional compound is preferably one or more, more preferably two to five.

[0105] Aromatic rings can be aromatic hydrocarbon rings or aromatic heterocycles.

[0106] Multifunctional compounds can also be polymers containing multiple repeating units.

[0107] When the multifunctional compound is a polymer, there is no particular limitation on the weight-average molecular weight of the multifunctional compound, but from the viewpoint of better performance of the present invention, it is preferably 10,000 or more, more preferably 15,000 or more. There is no particular upper limit, but it is preferably 30,000 or less, more preferably 25,000 or less.

[0108] In this invention, the weight-average molecular weight and number-average molecular weight are values ​​measured by gel permeation chromatography (GPC).

[0109] • Solvent (eluent): N-methylpyrrolidone

[0110] • Device Name: TOSOH HLC-8220GPC

[0111] • Column: Connect 3 TOSOH TSKgelSuperAWM-H (6mm×15cm) for use

[0112] Column temperature: 25℃

[0113] • Sample concentration: 0.1% by mass

[0114] • Flow rate: 0.35 mL / min

[0115] Calibration curves: Calibration curves for 7 samples of TSK standard polystyrene manufactured by TOSOH, with Mw = 2,800,000 to 1,050 (Mw / Mn = 1.03 to 1.06).

[0116] As a multifunctional compound, the compound represented by formula (A) or the compound represented by formula (B) is preferred.

[0117] Formula (A)R a1 -L a1 -R a2

[0118] In formula (A), R a1 and R a2 Each polymerizable group is represented independently. As described above, examples of polymerizable groups that liquid crystal compounds can possess can be cited as examples of polymerizable groups.

[0119] L a1 It refers to an alkylene group having 6 or more carbon atoms or a group represented by formula (A-1).

[0120] In equation (A-1), * represents the bonding position.

[0121] Formula (A-1)*-L a2 -L a3 -L a4 -*

[0122] L a2 and L a4 Each can be used independently to represent an alkylene group. L a3 It represents a divalent polycyclic aliphatic hydrocarbon group.

[0123] From the viewpoint that the present invention has superior effects, L a1 The alkylene groups with 6 or more carbon atoms mentioned above preferably have 8 or more carbon atoms. There is no particular upper limit, but it is preferably 20 or less, and more preferably 15 or less.

[0124] By L a2 and L a4 The number of carbon atoms in the alkylene group is not particularly limited, but from the viewpoint of better performance of the present invention, it is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1.

[0125] By L a3 The divalent polycyclic aliphatic hydrocarbon group is a divalent group formed by removing two hydrogen atoms from a polycyclic aliphatic hydrocarbon. Examples of polycyclic aliphatic hydrocarbons include norbornene ring, tricyclic decane ring, tetracyclic dodecane ring, and adamantane ring.

[0126] Formula (B)R b1 -Lb1 -L b2 -L b3 -L b4 -L b5 -R b2

[0127] In equation (B), R b1 and R b2 Each polymerizable group is represented independently. As described above, examples of polymerizable groups that liquid crystal compounds can possess can be cited as examples of polymerizable groups.

[0128] By L b1 and L b5 Each can independently represent an alkylene group that may contain an oxygen atom. (L) b1 and L b5 The number of carbon atoms in the alkylene group is not particularly limited, but is preferably 1 to 10, more preferably 1 to 3. (The last part, "from L," appears to be a typographical error and is left untranslated.) b1 and L b5 The alkylene group can be either straight-chain or branched.

[0129] L b2 and L b4 Each of these groups represents a divalent aromatic group independently. The aromatic ring constituting the divalent aromatic group can be a monocyclic or polycyclic ring. Examples of divalent aromatic groups include divalent aromatic hydrocarbon cyclic groups or divalent aromatic heterocyclic groups. Examples of aromatic hydrocarbon rings constituting divalent aromatic hydrocarbon cyclic groups include benzene rings, naphthalene rings, and fluorene rings.

[0130] L b3 Indicates an alkylene group or a divalent aromatic group. Derived from L... b3 The number of carbon atoms in the alkylene group is not particularly limited, but is preferably 1 to 5, more preferably 1 to 3. (The last part, "from L," appears to be a typographical error and is left untranslated.) b3 The alkylene group can be linear or branched. As a group composed of L... b3 The divalent aromatic group represented can be exemplified by L... b2 and L b4 The divalent aromatic group indicates the group.

[0131] When the multifunctional compound is a polymer, the multifunctional compound preferably contains repeating units represented by formula (C).

[0132] [Chemical Formula 1]

[0133]

[0134] In equation (C), R c1 This indicates a hydrogen atom or an alkyl group. The number of carbon atoms in an alkyl group is not particularly limited, but is preferably 1 to 3, more preferably 1.

[0135] L c1 This indicates a single bond or a divalent linking group. There are no particular limitations on the divalent linking group; examples include -COO-, -CO-, -O-, alkylene (preferably with 1 to 10 carbon atoms, more preferably with 1 to 5 carbon atoms), cycloalkylene (preferably with 3 to 20 carbon atoms), arylene (preferably with 6 to 20 carbon atoms), -SO-, -SO2-, -NH-, -NR-, and divalent linking groups formed by combining two or more of these. The R above represents an alkyl (preferably with 1 to 10 carbon atoms), a cycloalkyl (preferably with 3 to 20 carbon atoms), or an aryl (preferably with 6 to 20 carbon atoms).

[0136] Examples of divalent linking groups formed by combining two or more of them include -COO-alkylene- and -CONH-alkylene-.

[0137] The aforementioned alkylene groups can be straight-chain or branched. Furthermore, the alkylene groups can also contain cyclic structures such as aliphatic rings (preferably aliphatic cyclic hydrocarbons with 5 or more carbon atoms; more specifically, cyclohexane rings).

[0138] R c2 This refers to a polymerizable group. As mentioned above, examples of polymerizable groups that liquid crystal compounds can possess can be cited as examples of polymerizable groups.

[0139] When a multifunctional compound contains a repeating unit represented by formula (C), the content of the repeating unit represented by formula (C) is preferably 20 to 100% by mass, more preferably 40 to 100% by mass, relative to all repeating units of the multifunctional compound.

[0140] When the multifunctional compound is a polymer, the multifunctional compound preferably contains repeating units represented by formula (D).

[0141] [Chemical Formula 2]

[0142]

[0143] In equation (D), R d1 This indicates a hydrogen atom or an alkyl group. The number of carbon atoms in an alkyl group is not particularly limited, but is preferably 1 to 3, more preferably 1.

[0144] L d1 Indicates a single bond or a divalent linker. As a group composed of L... d1 The divalent linking group represented can be exemplified by the L group described above. c1 The divalent linker is an example of a group.

[0145] R d2 It indicates an alkyl or monovalent aromatic group.

[0146] There is no particular limitation on the number of carbon atoms in the alkyl group, but it is preferably 6 or more, more preferably 8 or more, and even more preferably 12 or more. There is no particular upper limit, but it is preferably 20 or less, and more preferably 15 or less.

[0147] The aromatic ring constituting a monovalent aromatic group can be a monocyclic or polycyclic ring. Examples of monovalent aromatic groups include monovalent aromatic hydrocarbon cyclic groups or monovalent aromatic heterocyclic groups. Examples of aromatic hydrocarbon rings constituting monovalent aromatic hydrocarbon cyclic groups include benzene rings, naphthalene rings, and fluorene rings.

[0148] When a multifunctional compound contains a repeating unit represented by formula (D), the content of the repeating unit represented by formula (D) is preferably 20 to 80% by mass, more preferably 40 to 60% by mass, relative to all repeating units of the multifunctional compound.

[0149] Furthermore, when the multifunctional compound contains repeating units represented by formulas (C) and (D), the content of the repeating unit represented by formula (C) is preferably 20 to 80% by mass, more preferably 40 to 60% by mass.

[0150] The cured polyfunctional compound is a product obtained by reacting (polymerizing) the polymerizable groups of the above-mentioned polyfunctional compound.

[0151] As described later, by using a polymerizable liquid crystal composition containing multifunctional compounds, the multifunctional compounds also react (polymerize) during the curing process when forming the liquid crystal layer, and the liquid crystal layer contains cured multifunctional compounds.

[0152] The content of the cured polyfunctional compound in the liquid crystal layer is not particularly limited. From the viewpoint of achieving better results in this invention, it is preferably 0.05 to 10.0% by mass, more preferably 0.10 to 5.0% by mass, relative to the total mass of the liquid crystal layer.

[0153] <Other Components>

[0154] Optical films may also include other components besides the stretched resin film and liquid crystal layer mentioned above.

[0155] The stretched resin film may also have a mixed layer between the stretched resin film and the liquid crystal layer, consisting of a cured material containing a polyfunctional compound and the resin constituting the stretched resin film.

[0156] As described later, when a polymeric liquid crystal composition is coated onto a stretched resin film to form a liquid crystal layer, depending on the components (especially solvents) contained in the polymeric liquid crystal composition, the surface of the stretched resin film may sometimes partially dissolve, forming a layer containing the resin and polyfunctional compounds contained in the stretched resin film, which is equivalent to a mixed layer.

[0157] When a hybrid layer is present, the optical film sequentially comprises a stretched resin film, a hybrid layer, and a liquid crystal layer. Furthermore, it is preferable that the stretched resin film and the hybrid layer are in direct contact, and it is also preferable that the hybrid layer and the liquid crystal layer are in direct contact.

[0158] The hybrid layer is equivalent to a layer containing two components: the resin that constitutes the stretched resin film and the cured polyfunctional compound.

[0159] The presence of the mixed layer can be determined using time-of-flight secondary ion mass spectrometry (TOF-SIMS). More specifically, while irradiating the surface of the liquid crystal layer from the side opposite to the stretched resin film side to the surface of the stretched resin film side with an ion beam, the composition of the liquid crystal layer in the depth direction is analyzed by time-of-flight secondary ion mass spectrometry. The distribution of the secondary ion intensity of each component in the depth direction is obtained, and the thickness region of the three components observed—the secondary ion intensity from the resin constituting the stretched resin film and the secondary ion intensity from the cured polyfunctional compound—corresponds to the mixed layer.

[0160] The thickness of the hybrid layer is not particularly limited, but from the viewpoint of achieving better results in this invention, it is preferably 5 to 50 nm.

[0161] Furthermore, in this specification, the thickness of the hybrid layer refers to the average thickness of the hybrid layer. This average thickness is calculated by taking the arithmetic average of the thicknesses measured at any five or more points along the hybrid layer using the TOF-SIMS method.

[0162] <Methods for Manufacturing Optical Films>

[0163] There are no particular limitations on the manufacturing method of the optical film of the present invention, and known methods can be used.

[0164] The preferred method is as follows: coating a polymeric liquid crystal composition containing a liquid crystal compound with polymeric groups (hereinafter also referred to as a polymeric liquid crystal compound) onto a stretched resin film, orienting the polymeric liquid crystal compound in the resulting coating film, and subjecting the coating film to a curing treatment.

[0165] The method of using the above-described liquid crystal composition will be described in detail below.

[0166] The polymerizable liquid crystal composition contains a polymerizable liquid crystal compound. As described above, examples of liquid crystal compounds include rod-shaped liquid crystal compounds and disc-shaped liquid crystal compounds.

[0167] The content of the polymeric liquid crystal compound in the polymeric liquid crystal composition is preferably 50-98% by mass, more preferably 70-95% by mass, relative to the total solid content of the composition.

[0168] In addition, solid components refer to components that can form a liquid crystal layer without solvent, and are also defined as solid components even if they are in liquid form.

[0169] Polymerizable liquid crystal compositions may also contain other components besides polymerizable liquid crystal compounds. Examples of such other components include polymerization initiators. The polymerization initiator used is selected based on the form of the polymerization reaction; for example, thermal polymerization initiators and photopolymerization initiators are examples.

[0170] The content of polymerization initiator in the polymerizable liquid crystal composition is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, relative to the total solid content of the composition.

[0171] Polymerizable liquid crystal compositions may also contain the aforementioned multifunctional compounds.

[0172] The content of the multifunctional compound in the polymeric liquid crystal composition is preferably 0.1 to 10.0% by mass, more preferably 0.2 to 5.0% by mass, relative to the total mass of the polymeric liquid crystal compound.

[0173] Other components that may be included in polymerizable liquid crystal compositions, in addition to those mentioned above, include orientation control agents (vertical orientation agents, horizontal orientation agents), surfactants, adhesive modifiers, plasticizers, and solvents.

[0174] Furthermore, to induce the twisted orientation of the liquid crystal compound, the polymerizable liquid crystal composition preferably contains a chiral agent. The chiral agent is added to induce the twisted orientation of the liquid crystal compound; however, in cases where the liquid crystal compound possesses optically active compounds such as asymmetric carbon atoms within its molecule, the addition of a chiral agent is unnecessary. Moreover, depending on the manufacturing method and the twist angle, the addition of a chiral agent may or may not be required.

[0175] As a chiral reagent, there are no particular structural limitations as long as it is a substance compatible with the liquid crystal compound to be used. Any of the known chiral reagents can also be used (e.g., "Handbook of Liquid Crystal Devices" edited by the 142nd Committee of the Japan Society for the Promotion of Science, Chapter 3, Item 4-3, TN and STN are chiral reagents, page 199, mid-1989).

[0176] There is no particular limit to the amount of chiral reagent used; the amount is adjusted to achieve the aforementioned torsion angle.

[0177] Examples of coating methods for polymerizable liquid crystal compositions include curtain coating, dip coating, spin coating, printing coating, spray coating, slot coating, roller coating, sliding coating, doctor blade coating, gravure coating, and wire rod coating.

[0178] Next, the formed coating film is subjected to an orientation treatment to orient the polymeric liquid crystal compound in the coating film.

[0179] Orientation processing can be performed by drying the coating at room temperature or by heating the coating. In the case of thermotropic liquid crystal compounds, the liquid crystal phase formed by orientation processing can generally be transferred according to changes in temperature or pressure. In the case of lyotropic liquid crystal compounds, transfer can also be achieved through compositional ratios such as solvent volume.

[0180] In addition, there are no particular restrictions on the conditions for heating the coating, but the heating temperature is preferably 50 to 250°C, more preferably 50 to 150°C, and the heating time is preferably 10 seconds to 10 minutes.

[0181] Furthermore, after heating the coating film, and before the curing process (light irradiation treatment) described later, the coating film can be cooled as needed.

[0182] Next, the coating film after the polymeric liquid crystal compound has been oriented is subjected to a curing process.

[0183] There are no particular limitations on the method of curing the coating film after the polymeric liquid crystal compound has been oriented; for example, light irradiation and heat treatment can be mentioned. From the viewpoint of manufacturing adaptability, light irradiation is preferred, and ultraviolet irradiation is more preferred.

[0184] There are no particular restrictions on the irradiation conditions for light treatment, but 50–1000 mJ / cm² is preferred. 2 The amount of radiation.

[0185] There are no particular restrictions on the atmosphere during light irradiation treatment, but a nitrogen atmosphere is preferred.

[0186] Furthermore, while the method of using a polymeric liquid crystal composition has been described above, the present invention is not limited to this method.

[0187] For example, a liquid crystal composition containing a liquid crystal compound that does not have polymerizable groups can be used.

[0188] Furthermore, a stretched resin film and a liquid crystal layer can be separately fabricated and bonded together via an adhesive layer (e.g., an adhesive layer and a bonding layer) to manufacture the optical film of the present invention.

[0189] <Uses>

[0190] The aforementioned optical film can be used for various applications. For example, the in-plane delay of the optical film can be adjusted to use it as a so-called λ / 4 plate or λ / 2 plate.

[0191] In addition, a λ / 4 plate refers to a plate that has the function of converting linearly polarized light of a specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). More specifically, it is a plate whose in-plane delay Re at a specified wavelength λnm is represented by λ / 4 (or an odd multiple thereof).

[0192] The in-plane delay (Re(550)) of the λ / 4 plate at a wavelength of 550nm can have an error of about 25nm centered on the ideal value (137.5nm), for example, preferably 110-160nm, more preferably 120-150nm.

[0193] Furthermore, the λ / 2 plate refers to an optically anisotropic film whose in-plane retardation Re(λ) at a specific wavelength λnm satisfies Re(λ)≈λ / 2. This formula can be implemented at any wavelength in the visible light region (e.g., 550nm). Preferably, the in-plane retardation Re(550) at a wavelength of 550nm satisfies the following relationship.

[0194] 210nm≤Re(550)≤300nm

[0195] <Polarizer>

[0196] The optical film of the present invention is preferably applicable to polarizers.

[0197] That is, the polarizer (preferably a circular polarizer) of the present invention includes an optical film and a polarizer. Furthermore, a circular polarizer refers to an optical element that converts unpolarized light into circularly polarized light.

[0198] A polarizer is any component that can convert light into linearly polarized light (a linear polarizer), and absorption polarizers can be used as the primary type.

[0199] Examples of absorption-type polarizers include iodine-based polarizers, dye-based polarizers utilizing dichroic dyes, and polyene-based polarizers. Iodine-based and dye-based polarizers include coated polarizers and stretched polarizers, both of which are applicable, but polarizers made by adsorbing iodine or dichroic dyes onto polyvinyl alcohol and then stretching it are preferred.

[0200] <Image display device>

[0201] The optical film of the present invention is preferably applicable to image display devices.

[0202] The image display device of the present invention includes a display element and the aforementioned optical film.

[0203] When the optical film of the present invention is applied to an image display device, it can also be used as the aforementioned polarizer. That is, the image display device of the present invention may also include a display element, the aforementioned optical film, and a polarizer. In this case, the optical film and polarizer of the present invention are preferably configured as a circular polarizer, with the circular polarizer disposed on the visual recognition side, and the polarizer disposed on the visual recognition side within the circular polarizer.

[0204] There are no particular limitations on image display elements; examples include organic electroluminescent display elements and liquid crystal display elements.

[0205] Example

[0206] The following examples and comparative examples further illustrate the features of the present invention. Regarding the materials, amounts, proportions, processing contents, and processing steps shown in the following examples, appropriate modifications can be made without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as limited by the specific examples shown below.

[0207] <Manufacturing of Stretched Resin Film 1>

[0208] Particles of norbornene resin (manufactured by Zeon Corporation, ZEONOR1420) were formed using a T-die film extrusion machine to obtain an unstretched cyclic olefin polymer substrate with a thickness of 100 μm.

[0209] The resulting unstretched resin film was stretched longitudinally and then stretched obliquely to obtain an obliquely stretched resin film. The stretching temperature and magnification were adjusted to an in-plane retardation of 180 nm and a slow axis angle of -13° at a wavelength of 550 nm.

[0210] Furthermore, when viewed from the surface of the resulting stretched resin film (the side where the liquid crystal layer is formed), the aforementioned slow axis direction is clockwise relative to the film transport direction, indicated by a negative value.

[0211] <Manufacturing of Stretch Resin Film 2>

[0212] Syndiotactic polystyrene ("130-ZC" manufactured by Idemitsu Kosan Co., Ltd., with a glass transition temperature of 98°C and a crystallization temperature of 140°C) was fed into a twin-screw extruder and melt-extruded into sheets at approximately 280°C to obtain an unstretched resin film with a thickness of 100 μm.

[0213] The resulting unstretched resin film was stretched longitudinally and then stretched obliquely to obtain an obliquely stretched resin film. The stretching temperature and magnification were adjusted to an in-plane retardation of 180 nm and a slow axis angle of -13° at a wavelength of 550 nm.

[0214] <Example 1>

[0215] A polymeric liquid crystal composition (1) containing rod-shaped liquid crystal compounds of the following composition was coated onto a stretched resin film 1 using a die-coating machine to form a coating film. The resulting coating film was then heated at 90°C for 100 seconds. This heating resulted in a twisted layer with the rod-shaped liquid crystal compounds in the coating film twisted and oriented. Then, nitrogen purging was performed to achieve an oxygen concentration of 100 ppm by volume. The orientation state of the liquid crystal compounds was fixed by irradiating the coating film with ultraviolet light using a metal halide lamp (manufactured by EYE GRAPHICS CO.,LTD.), thereby producing an optical film 1 (irradiation dose: 500 mJ / cm). 2 ).

[0216]

[0217]

[0218] Rod-shaped liquid crystal compound (A)

[0219] [Chemical Formula 3]

[0220]

[0221] Rod-shaped liquid crystal compound (B)

[0222] [Chemical Formula 4]

[0223]

[0224] Polymerizable compounds (C)

[0225] [Chemical Formula 5]

[0226]

[0227] Left-handed tortuous chiral reagent (L1)

[0228] [Chemical Formula 6]

[0229]

[0230] Polymer (A) (where the values ​​recorded in each repeating unit represent the content (mass%) of each repeating unit relative to all repeating units.)

[0231] [Chemical Formula 7]

[0232]

[0233] A-DCP (Tricyclodecanedimethyl diacrylate)

[0234] [Chemical Formula 8]

[0235]

[0236] <Examples 2-12, Comparative Examples 2-3, Comparative Example 5>

[0237] The types of stretching resin film, solvent and multifunctional compound were changed as shown in the table below. Otherwise, optical films 2-12, optical film C2, optical film C3 and optical film C5 were prepared according to the same steps as in Example 1.

[0238] <Comparative Example 1>

[0239] The optical film C1 was prepared by using a polymeric liquid crystal composition (2) instead of a polymeric liquid crystal composition (1), except that the same steps as in Example 1 were followed.

[0240]

[0241] <Comparative Example 4>

[0242] The types of stretching resin film, solvent, and multifunctional compound were changed as shown in the table below. Otherwise, the optical film C4 was prepared following the same steps as in Comparative Example 1.

[0243] In addition, the optical properties of the liquid crystal layer contained in the optical films of each embodiment and comparative example were determined using AxoScan from Axometrics and the company's analysis software (Multi-Layer Analysis).

[0244] In the optical films of Examples 1-12 and Comparative Examples 2-4, the product of Δn and thickness d (Δnd) of the liquid crystal layer at a wavelength of 550 nm is 180 nm, the twist angle of the liquid crystal compound is 80°, and the orientation axis angle of the liquid crystal compound relative to the strip length direction (transport direction) is -13° on the surface of the stretching resin film side of the liquid crystal layer and -93° on the surface of the air interface side of the liquid crystal layer, thus forming a twisted orientation in the liquid crystal layer.

[0245] In the optical film of Comparative Example 1, the product of Δn and thickness d (Δnd) of the liquid crystal layer at a wavelength of 550 nm is 180 nm, the twist angle of the liquid crystal compound is 0°, and the orientation axis angle of the liquid crystal compound relative to the strip length direction (transport direction) is -13° on the surface of the stretching resin film side of the liquid crystal layer and -13° on the surface of the air interface side of the liquid crystal layer, exhibiting uniform orientation.

[0246] Furthermore, when viewed from the liquid crystal layer side of the obtained optical film, the aforementioned orientation axis angle relative to the length direction of the strip (transport direction) is expressed as a negative value in clockwise direction.

[0247] <Fabrication of Circular Polarizers>

[0248] (Making a polarizer)

[0249] A polyvinyl alcohol (PVA) film with a thickness of 80 μm was stained by immersing it in an aqueous iodine solution with a concentration of 0.05% by mass at 30 °C for 60 seconds. Next, the resulting film was longitudinally stretched to five times its original length while being immersed in an aqueous boric acid solution with a concentration of 4% by mass for 60 seconds, and then dried at 50 °C for 4 minutes to obtain a polarizer with a thickness of 20 μm.

[0250] (Fabrication of polarizer protective film)

[0251] A commercially available cellulose acylated membrane, FUJI TAC TG40UL (manufactured by FUJIFILM Corporation), was prepared by immersing it in a 1.5 mol / L sodium hydroxide aqueous solution at 55°C, followed by thorough rinsing with water. Then, the resulting membrane was immersed in a 0.005 mol / L dilute sulfuric acid aqueous solution at 35°C for 1 minute, followed by immersion in water and thorough rinsing with the dilute sulfuric acid aqueous solution. Finally, the resulting membrane was thoroughly dried at 120°C to produce a polarizer protective film with a saponified surface.

[0252] (Fabrication of a circular polarizer)

[0253] Using a polyvinyl alcohol-based adhesive, the polarizer and the polarizer protective film are continuously bonded together to obtain a polarizer with a polarizer protective film.

[0254] The stretched resin film sides of the optical films 1-12 and C1-C5 prepared above were bonded to the polarizer side of the polarizer with the polarizer protective film using adhesive SK2057 (manufactured by Soken Chemical & Engineering Co., Ltd.) to create a long strip-shaped circular polarizer.

[0255] Then, adhesive SK2057 (manufactured by Soken Chemical & Engineering Co., Ltd.) with a single-sided spacer is bonded to the liquid crystal layer side of the optical film to obtain laminates 1 to 12 containing a circular polarizer and laminates C1 to C5. The laminates sequentially include a polarizer protective film, a polarizer, an adhesive, a stretching resin film, a liquid crystal layer, an adhesive, and a spacer.

[0256] <Evaluation>

[0257] (Evaluation of TOF-SIMS)

[0258] While etching the surface of the liquid crystal layer on the side opposite to the stretched resin film, TOF-SIMS is measured to obtain the depth-direction distribution of the secondary ion intensity from the cured multifunctional compound and the secondary ion intensity from the resin contained in the stretched resin film before reaching the stretched resin film.

[0259] Based on the obtained depth direction distribution, the thickness region of both the secondary ion strength from the cured polyfunctional compound and the secondary ion strength from the resin contained in the stretched resin film was identified as the hybrid layer before reaching the stretched resin film, and the thickness of the hybrid layer was evaluated according to the following criteria.

[0260] 1: The thickness of the hybrid layer is less than 5nm

[0261] 2: The thickness of the hybrid layer is 5–50 nm.

[0262] 3: The thickness of the hybrid layer exceeds 50nm but is less than 100nm.

[0263] 4: The thickness of the hybrid layer exceeds 100nm

[0264] Based on the depth distribution obtained above, the case where the cured multifunctional compound exists on the surface of the stretched resin film side more than on the surface of the liquid crystal layer opposite to the stretched resin film side is designated as "A", otherwise it is designated as "B".

[0265] (Evaluation of the impact factor)

[0266] The laminate containing the circular polarizer was placed in a constant temperature bath (manufactured by ESPEC CORP.) at 80°C for 24 hours, followed by 3 hours of humidification in a room at 25°C and 60% relative humidity. Four polarizer sheets were then punched from the protective film side using a 4cm × 4cm Thomson blade (manufactured by Nakayama Co., Ltd.). The 4cm × 4cm polarizer samples were examined for crack patterns on each side using a magnifying glass and evaluated according to the following criteria. In practical applications, a value above C is acceptable.

[0267] A: No cracks will form.

[0268] B: A crack less than 0.1 mm appeared on the punching end face.

[0269] C: A crack of 0.1 mm or more but less than 0.2 mm was generated from the punching end face.

[0270] D: A crack of more than 0.2 mm was generated from the punching end face.

[0271] Furthermore, in the evaluations B to D above, cracks were found on the optical film.

[0272] Table 1 shows the δa values ​​of the resin and polyfunctional compounds contained in the stretched resin film calculated by the above method.

[0273] Additionally, the three-dimensional solubility parameters (δd, δp, δh) for COP are (18.0, 3.0, 2.0). The three-dimensional solubility parameters (δd, δp, δh) for PSt are (18.5, 4.5, 2.9). The HSP values ​​for multifunctional compounds were calculated by inputting the SMILES values ​​of each multifunctional compound in the DIY function of HSPip (ver. 5.1.08).

[0274] In Table 1, the "Type" column of the "Stretch Resin Film" column indicates the stretch resin film used. "COP" indicates stretch resin film 1, and "PSt" indicates that stretch resin film 2 was used.

[0275] In Table 1, the "Orientation State" column of the "Liquid Crystal Layer" column indicates the orientation state of the liquid crystal compound. "Twisted" means that the twisted orientation of the liquid crystal compound is fixed, and "Uniform" means that the uniform orientation of the liquid crystal compound is fixed.

[0276] In Table 1, the "Solvent" column under the "Liquid Crystal Layer" section indicates the types of solvents contained in the polymeric liquid crystal composition. Additionally, the designation "A / B=50 / 50" indicates that solvent A and solvent B are mixed in a 50:50 mass ratio.

[0277] In Table 1, the "Molecular Weight" column in the "Multifunctional Compounds" section represents the weight-average molecular weight of the corresponding multifunctional compounds.

[0278] In Table 1, the "δa" column in the "Multifunctional Compounds" section represents the δa of the multifunctional compounds.

[0279] In Table 1, the "Difference in δa" column represents the absolute value of the difference between the δa of the resin contained in the stretched resin film and the δa of the polyfunctional compound.

[0280] In addition, all the multifunctional compounds shown in Table 1 are non-liquid crystals.

[0281] In Table 1, polymer (B) is represented by the following formula. The “40” and “60” listed in each repeating unit indicate the content (mass%) of each repeating unit relative to all repeating units in the polymer.

[0282] [Chemical Formula 9]

[0283]

[0284] In Table 1, polymer (C) is represented by the following formula. The "100" listed in each repeating unit indicates the content (mass %) of the repeating unit relative to all repeating units in the polymer.

[0285] [Chemical Formula 10]

[0286]

[0287] In Table 1, polymer (D) is represented by the following formula. The “50” and “50” in each repeating unit indicate the content (mass%) of each repeating unit relative to all repeating units in the polymer.

[0288] [Chemical Formula 11]

[0289]

[0290] In Table 1, polymer (E) is represented by the following formula. The "100" listed in each repeating unit indicates the content (mass %) of the repeating unit relative to all repeating units in the polymer.

[0291] [Chemical Formula 12]

[0292]

[0293] [Table 1]

[0294]

[0295]

[0296] As shown in Table 1, the optical film of the present invention exhibits the desired effect.

[0297] By comparing Examples 1 to 3, it was confirmed that the effect was better when the thickness of the hybrid layer was 5 to 50 nm.

[0298] By comparing Examples 4 and 5, it was confirmed that the polyfunctional compound with a straight-chain hydrocarbon group having 8 or more carbon atoms has a better effect.

[0299] By comparing Examples 6, 7 and 11, it was confirmed that the multifunctional compound had better performance when it was a polymer with a weight average molecular weight of 10,000 or more.

[0300] By comparing Examples 8 and 9, it was confirmed that when more of the cured multifunctional compound exists on the surface of the stretched resin film side compared to the surface of the liquid crystal layer opposite to the stretched resin film side, the effect is better.

[0301] By comparing Examples 9 and 12, it was confirmed that the stretch resin film containing polystyrene, having a non-liquid crystal structure, and possessing more than one aromatic ring exhibits superior performance.

Claims

1. An optical film having: Stretched resin film; and A liquid crystal layer is formed by fixing a liquid crystal compound that is twisted and oriented along a helical axis extending in the thickness direction. The δa value calculated using the three-dimensional solubility parameters of the resin in the stretched resin film is 8.0 MPa. 1 / 2 the following, The liquid crystal layer comprises a cured product of a multifunctional compound having two or more polymerizable groups in one molecule. The absolute value of the difference between the δa value calculated using the three-dimensional solubility parameters of the multifunctional compound and the δa value calculated using the three-dimensional solubility parameters of the resin is 4.0 MPa. 1 / 2 the following.

2. The optical film according to claim 1, wherein, Compared to the surface of the liquid crystal layer opposite to the stretching resin film side, the cured polyfunctional compound is more present on the surface of the stretching resin film side.

3. The optical film according to claim 1 or 2, wherein, Between the stretched resin film and the liquid crystal layer, there is also a mixed layer containing a cured product of the polyfunctional compound and a resin constituting the stretched resin film.

4. The optical film according to claim 3, wherein, The thickness of the hybrid layer is 5–50 nm.

5. The optical film according to claim 1 or 2, wherein, The stretched resin film comprises a resin selected from the group consisting of cyclic olefin polymers and polystyrene.

6. The optical film according to claim 1 or 2, wherein, The stretched resin film comprises a cyclic olefin polymer. The multifunctional compound is non-liquid crystal and has a hydrocarbon group having 5 or more carbon atoms.

7. The optical film according to claim 6, wherein, The polyfunctional compound has at least one group selected from the group consisting of straight-chain hydrocarbon groups having 8 or more carbon atoms and cyclic hydrocarbon groups having 5 or more carbon atoms.

8. The optical film according to claim 1 or 2, wherein, The stretched resin film comprises polystyrene. The multifunctional compound is non-liquid crystal and has one or more aromatic rings.

9. The optical film according to claim 1 or 2, wherein, The weight-average molecular weight of the multifunctional compound is above 10,000.

10. The optical film according to claim 1 or 2, wherein, The in-plane retardation of the stretched resin film at a wavelength of 550 nm is 100–250 nm.

11. The optical film according to claim 1 or 2, wherein, The twist angle of the liquid crystal compound is 60–100°. The product of the refractive index anisotropy Δn of the liquid crystal layer at a wavelength of 550 nm and the thickness d of the liquid crystal layer, Δnd, is 100–250 nm.

12. A circular polarizer comprising the optical film according to any one of claims 1 to 11.

13. An image display device comprising the optical film according to any one of claims 1 to 11.

Images