Optical film, method for producing optical film, polarizing plate, and image display device

Abstract

The present invention addresses the problem of providing: an optical film which has improved alignment of a liquid crystal compound in an optically anisotropic layer and which is prevented from the occurrence of bright spot defects; a method for producing an optical film; a polarizing plate; and an image display device. The optical film according to the present invention comprises a support and an optically anisotropic layer which are located adjacent to each other, in which the optically anisotropic layer is a layer formed using an optically anisotropic layer-forming composition containing a polymerizable liquid crystal compound, the support contains a surfactant having a hydrophilic group and a hydrophobic group, and the hydrophobic group is at least one group selected from the group consisting of an alkyl group having 5 to 29 carbon atoms, a silicon-containing group, and a fluorine-containing group.

Description

Optical film, method for producing optical film, polarizing plate and image display device

[0001] The present invention relates to an optical film, a method for producing an optical film, a polarizing plate, and an image display device.

[0002] Optical films such as optical compensation sheets and retardation films are used in various image display devices to eliminate image coloration or widen the viewing angle. Stretched birefringent films have been used as optical films, but in recent years, it has been proposed to use optical films having an optically anisotropic layer made of a liquid crystal compound instead of stretched birefringent films.

[0003] When forming such an optically anisotropic layer, an alignment film is usually used. For example, Patent Document 1 describes an embodiment in which an optically anisotropic layer is formed on an alignment film formed using a coating liquid containing polyvinyl alcohol having a specific group ([Claim 1], [Claim 2], [Example]).

[0004] Japanese Patent Application Publication No. 9-152509

[0005] From the viewpoint of achieving thinner films and simplifying the manufacturing process, the present inventors have investigated the manufacture of optical films in which a support (base material) is subjected to a rubbing treatment and an optically anisotropic layer is adjacent to the support without using an alignment film. They have found that although the alignment of the liquid crystal compound in the optically anisotropic layer is good, debris from the support is scattered during the rubbing treatment, and this debris can cause bright spot defects in optical films having an optically anisotropic layer.

[0006] Therefore, an object of the present invention is to provide an optical film in which the alignment of liquid crystal compounds in an optically anisotropic layer is improved and the occurrence of bright spot defects is suppressed. Another object of the present invention is to provide a method for producing the optical film, a polarizing plate, and an image display device.

[0007]

[0009] As a result of intensive research to achieve the above object, the present inventors have found that by using a support containing a surfactant having a hydrophilic group and a specific hydrophobic group, the alignment of liquid crystal compounds in an optically anisotropic layer is improved and the occurrence of bright spot defects in an optical film can be suppressed, thereby completing the present invention. That is, the present inventors have found that the above object can be achieved by the following configuration.

[0008] [1] An optical film having a support and an optically anisotropic layer adjacent to each other, wherein the optically anisotropic layer is formed using a composition for forming an optically anisotropic layer containing a polymerizable liquid crystal compound, wherein the support contains a surfactant having a hydrophilic group and a hydrophobic group, and wherein the hydrophobic group is at least one group selected from the group consisting of an alkyl group having 5 to 29 carbon atoms, a silicon-containing group, and a fluorine-containing group. [2] The optical film according to [1], wherein the optically anisotropic layer is a layer in which the orientation state of the polymerizable liquid crystal compound is fixed, and wherein the orientation state is a homogeneous orientation or a twisted orientation. [3] The optical film according to [1] or [2], wherein the support is a cellulose acylate film. [4] The optical film according to any one of [1] to [3], wherein the hydrophilic group of the surfactant is an ionic hydrophilic group. [5] The optical film according to any one of [1] to [4], wherein the hydrophilic group of the surfactant is an anionic hydrophilic group. [6] The optical film according to any one of [1] to [5], wherein the surfactant is a polymer compound. [7] The optical film according to any one of [1] to [6], wherein the hydrophobic group of the surfactant is an alkyl group having 12 to 18 carbon atoms. [8] A method for producing an optical film, comprising: a support preparation step of preparing the support according to [1]; a rubbing step of subjecting the support to a rubbing treatment; and an optically anisotropic layer formation step of forming an optically anisotropic layer on the rubbed support using an optically anisotropic layer-forming composition containing a polymerizable liquid crystal compound. [9] A method for producing the optical film according to [8], wherein the support preparation step comprises a step of casting a dope containing the surfactant according to [1].

[10] A method for producing the optical film according to [8] or [9], wherein the support preparation step comprises a step of impregnating a surface of a polymer film with a composition containing the surfactant according to [1] and a solvent.

[11] A polarizing plate comprising the optical film according to any one of [1] to [7], and a polarizer.

[12] An image display device having the optical film according to any one of [1] to [7].

[13] The image display device according to

[12] , which is a liquid crystal display device.

[14] The image display device according to

[12] , which is an organic electroluminescence display device.

[0009] According to the present invention, an optical film can be provided in which the alignment of a liquid crystal compound in an optically anisotropic layer is improved and the occurrence of bright spot defects is suppressed. Furthermore, according to the present invention, a method for producing the optical film, a polarizing plate, and an image display device can be provided.

[0010] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, each component may be used alone or in combination with two or more substances corresponding to the component. When two or more substances are used in combination for each component, the content of the component refers to the total content of the substances used in combination, unless otherwise specified. In this specification, "(meth)acrylate" refers to "acrylate" or "methacrylate," "(meth)acrylic" refers to "acrylic" or "methacrylic," and "(meth)acryloyl" refers to "acryloyl" or "methacryloyl."

[0011] [Optical Film] The optical film of the present invention has a support and an optically anisotropic layer adjacent to each other. The optically anisotropic layer of the optical film of the present invention is formed using an optically anisotropic layer-forming composition containing a polymerizable liquid crystal compound. The support of the optical film of the present invention contains a surfactant having a hydrophilic group and a hydrophobic group, and the hydrophobic group of the surfactant is at least one group selected from the group consisting of alkyl groups having 5 to 29 carbon atoms, silicon-containing groups, and fluorine-containing groups (hereinafter, also referred to as "specific hydrophobic group"). In the following description, the surfactant having a hydrophilic group and a specific hydrophobic group will also be referred to as "specific surfactant."

[0012] In the present invention, as described above, the use of a support containing a specific surfactant improves the alignment of liquid crystal compounds in the optically anisotropic layer and suppresses the occurrence of bright spot defects in the optical film. The reasons for these effects are not fully understood, but the inventors speculate as follows. Specifically, the use of a support containing a specific surfactant reduces friction between the support and the pile of the rubbing cloth used when rubbing the support, thereby reducing the amount of dust generated from the support, thereby suppressing the occurrence of bright spot defects. Furthermore, the specific surfactant having a specific hydrophobic group maintains compatibility with the main component of the support, allowing the specific surfactant to be uniformly present on the support surface while maintaining a moderately exposed state without being completely covered by the specific surfactant. This is thought to improve the alignment of liquid crystal compounds in the optically anisotropic layer formed on the support. The alignment film and optically anisotropic layer of the optical film of the present invention will now be described in detail.

[0013] [Support] The support of the optical film of the present invention is a support containing a specific surfactant. Here, in the present invention, the support refers to a base material containing the components of the support. For example, when forming an optically anisotropic layer described later, if a part of the components of the optically anisotropic layer penetrates into the support to form a mixed layer of the components of the support and the components of the optically anisotropic layer, the mixed layer is a layer contained in the support.

[0014] The type of support is not particularly limited, and known supports can be used. In particular, a transparent support is preferred. The transparent support refers to a support having a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more.

[0015] The support is preferably a polymer film. Examples of polymer films include cellulose acylate films (e.g., cellulose triacetate film, cellulose diacetate film, cellulose acetate butyrate film, and cellulose acetate propionate film), polyacrylic resin films such as polymethyl methacrylate, polyolefins such as polyethylene and polypropylene, polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyether ketone films, (meth)acrylonitrile films, polyolefins, and polymers having an alicyclic structure (norbornene resins (Arton: product name, manufactured by JSR Corporation), amorphous polyolefins (Zeonex: product name, manufactured by Nippon Zeon Co., Ltd.)). Among these, cellulose acylate films are preferred as the support because they provide better alignment of the liquid crystal compound in the optically anisotropic layer. The support may also be peelable.

[0016] The thickness of the support is preferably from 20 to 100 μm, and more preferably from 25 to 60 μm.

[0017] <Specific Surfactant> The specific surfactant contained in the support is a surfactant having a hydrophilic group and a specific hydrophobic group.

[0018] (Specific Hydrophobic Group) As described above, the specific hydrophobic group contained in the specific surfactant is at least one group selected from the group consisting of an alkyl group having 5 to 29 carbon atoms, a silicon-containing group, and a fluorine-containing group.

[0019] Examples of the alkyl group include pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl (cetyl), octadecyl, icosyl, docosyl, tetracosyl, hexacosyl, and nonacosyl groups. The alkyl group may be a linear or branched alkyl group, but is preferably a linear alkyl group.

[0020] Examples of the silicon-containing group include groups represented by the following formula (S-1): Formula (S-1) -Si(Ra)x(Rb)y, where Ra represents a hydroxyl group or a hydrolyzable group. Rb represents a non-hydrolyzable group. x represents an integer of 1 to 3, y represents an integer of 0 to 2, and the relationship x + y = 3 is satisfied. The hydrolyzable group represents a group capable of generating a silanol group or a group capable of forming a siloxane condensate, and specific examples include a halogen group, an alkoxy group, an acyloxy group, and an isocyanate group. Of these, an alkoxy group (preferably having 1 to 2 carbon atoms) is preferred. Examples of the non-hydrolyzable group include a hydrogen atom, an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, or an alkynyl group, an aromatic hydrocarbon group such as an aryl group, or a combination thereof.

[0021] Examples of the fluorine-containing group include alkyl groups containing fluorine atoms, and specific examples thereof include groups represented by the following formula (F-1): Formula (F-1) -La-Cf where Cf represents a fluorine-containing alkyl group. The fluorine-containing alkyl group represents an alkyl group containing a fluorine atom, and is preferably a perfluoroalkyl group. The number of carbon atoms in the fluorine-containing alkyl group is not particularly limited, and is preferably 1 to 30, more preferably 3 to 20, and even more preferably 5 to 10, because this improves the alignment of the liquid crystal compound in the optically anisotropic layer. The number of fluorine atoms contained in the fluorine-containing alkyl group is not particularly limited, and is preferably 1 to 30, more preferably 5 to 25, and even more preferably 10 to 20, because this improves the alignment of the liquid crystal compound in the optically anisotropic layer. Furthermore, La represents a single bond or a divalent linking group. Examples of the divalent linking group represented by one embodiment of La include a divalent hydrocarbon group which may have a substituent, a divalent heterocyclic group which may have a substituent, -O-, -S-, -N(Q)-, -CO-, or a combination thereof. Q represents a hydrogen atom or a substituent. Examples of the divalent hydrocarbon group include divalent aliphatic hydrocarbon groups such as alkylene groups having 1 to 10 carbon atoms, alkenylene groups having 1 to 10 carbon atoms, and alkynylene groups having 1 to 10 carbon atoms, and divalent aromatic hydrocarbon groups such as arylene groups. Examples of the divalent heterocyclic group include divalent aromatic heterocyclic groups, and specific examples thereof include a pyridylene group (pyridine-diyl group), a pyridazine-diyl group, an imidazole-diyl group, a thienylene group (thiophene-diyl group), and a quinolylene group (quinoline-diyl group). Examples of groups combining these include groups combining at least two or more selected from the group consisting of the above-mentioned divalent hydrocarbon groups, divalent heterocyclic groups, -O-, -S-, -N(Q)-, and -CO-, and examples thereof include -O-divalent hydrocarbon group-, -divalent hydrocarbon group -O-, and -divalent hydrocarbon group -N(Q)-. １Preferably, the divalent linking group is a combination of at least two groups selected from the group consisting of a linear alkylene group having 1 to 10 carbon atoms which may have a substituent, a branched alkylene group having 3 to 10 carbon atoms which may have a substituent, a cyclic alkylene group having 3 to 10 carbon atoms which may have a substituent, an arylene group having 6 to 12 carbon atoms which may have a substituent, -O-, and -N(Q)-, and more preferably a divalent linking group is a combination of at least two groups selected from the group consisting of a linear alkylene group having 1 to 10 carbon atoms which may have a substituent, a cyclic alkylene group having 3 to 10 carbon atoms which may have a substituent, -O-, and -NH-. Note that examples of the substituents that the above-mentioned divalent hydrocarbon groups (including alkylene groups) and divalent heterocyclic groups may have, as well as the substituents represented by one embodiment of Q, include, for example, halogen atoms, alkyl groups, alkoxy groups, aryl groups, aryloxy groups, cyano groups, carboxy groups, alkoxycarbonyl groups, and hydroxyl groups.

[0022] In the present invention, the specific hydrophobic group is preferably an alkyl group having 5 to 29 carbon atoms, more preferably an alkyl group having 10 to 25 carbon atoms, and even more preferably an alkyl group having 12 to 18 carbon atoms, because this further suppresses the occurrence of bright spot defects in the optical film.

[0023] (Hydrophilic Group) The hydrophilic group possessed by the specific surfactant is not particularly limited, and both ionic hydrophilic groups (anionic hydrophilic groups, cationic hydrophilic groups, amphoteric hydrophilic groups) and nonionic hydrophilic groups can be used. Examples of anionic hydrophilic groups include hydroxy groups, carboxy groups, carboxylates, sulfonic acid groups, sulfonates, sulfates, phosphate groups, and phosphate ester salts. Examples of cationic hydrophilic groups include amino groups and quaternary ammonium salts. The nonionic hydrophilic group may be any of ester, ether, ester-ether, and alkanolamide types, with ether types being preferred, and polyoxyalkylene groups (e.g., polyoxyethylene groups, polyoxypropylene groups, polyoxyalkylene groups in which oxyethylene groups and oxypropylene groups are bonded in block or random bonds, etc.) being more preferred.

[0024] Among such hydrophilic groups, an ionic hydrophilic group is preferred, and an anionic hydrophilic group is more preferred, because this improves the alignment of the liquid crystal compound in the optically anisotropic layer and further suppresses the occurrence of bright spot defects in the optical film (hereinafter also abbreviated as "the reason why the effects of the present invention are superior").

[0025] In the present invention, the specific surfactant may be a low-molecular-weight compound or a high-molecular-weight compound. Here, the term "low-molecular-weight compound" refers to a specific surfactant having a molecular weight of 100 or more but less than 2,000. The term "high-molecular-weight compound" refers to a specific surfactant having a molecular weight of 2,000 or more, and the weight-average molecular weight (Mw) is preferably 5,000 to 40,000, more preferably 8,000 to 39,000, and even more preferably 10,000 to 35,000. A weight-average molecular weight of 10,000 or more suppresses unevenness during the formation of an optically anisotropic layer, while a weight-average molecular weight of 40,000 or less improves the alignment of the liquid crystal compound in the optically anisotropic layer.

[0026] In the present invention, the specific surfactant is preferably a polymer compound, since this provides better effects of the present invention.

[0027] Specific examples of low molecular weight compounds among the specific surfactants include sodium dodecyl sulfate, polyoxyethylene (10) cetyl ether, polyoxyethylene (20) docosyl ether, tetrahexylammonium bromide, tetra-n-octylammonium bromide, trimethylstearylammonium bromide, and melissic acid.

[0028] Among the specific surfactants, examples of polymeric compounds include polymers having the above-mentioned specific hydrophobic groups and hydrophilic groups on the side chains of a (meth)acrylic polymer. Such polymers are preferably copolymers having a side chain having the above-mentioned specific hydrophobic group (hereinafter also referred to as the "hydrophobic part") and a side chain having the above-mentioned hydrophilic group (hereinafter also referred to as the "hydrophilic part") in separate repeating units. The hydrophobic part is not particularly limited as long as it has the above-mentioned specific hydrophobic group, but preferably has a polyoxyalkylene group as a linking group on the main chain and an alkyl group having 12 to 22 carbon atoms on the terminal end. The hydrophilic part is not particularly limited as long as it has the above-mentioned hydrophilic group, but preferably has a side chain having a polyoxyalkylene group, and more preferably has a side chain having a polyoxyethylene group.

[0029] Examples of the monomer that forms such a hydrophobic part include the following: In the following formula, n represents an integer of 2 to 50.

[0030] Examples of the monomer that forms such a hydrophilic part include the following: In the following formula, n represents an integer of 2 to 50.

[0031] In the present invention, the content of the specific surfactant contained in the support is preferably 0.1 to 20 mass %, more preferably 0.2 to 10 mass %, and even more preferably 0.3 to 5 mass %, relative to the total mass of the support.

[0032] In the present invention, at least a portion of the specific surfactant contained in the support is preferably present in a region extending from the surface of the support on the optically anisotropic layer side to 10% of the thickness of the optically anisotropic layer (hereinafter referred to as the "surface region"). The presence of the specific surfactant in the surface region of the support can be confirmed, for example, by time-of-flight secondary ion mass spectrometry (TOF-SIMS). The TOF-SIMS method can be the method described in "Surface Analysis Technology Selection: Secondary Ion Mass Spectrometry" edited by the Japan Surface Science Society and published by Maruzen Co., Ltd. in 1999. Specifically, the analysis is performed by repeatedly irradiating an ion beam and measuring with TOF-SIMS from the interface on the optically anisotropic layer side of the support. The ion beam irradiation and TOF-SIMS measurement are performed by first analyzing the components of a region extending from the surface to a depth of 1 to 2 nm in the thickness direction (hereinafter referred to as the "surface region"), and then digging further in the thickness direction by 1 to several hundred nm to perform the component analysis of the next surface region. This series of operations is repeated. The distribution of the specific surfactant in the thickness direction of the support is analyzed by measuring the secondary ion intensity derived from the hydrophilic group and the specific hydrophobic group. The type of ion beam used may be, for example, an ion beam produced by an argon gas cluster ion gun (Ar-GCIB gun).

[0033] [Optically Anisotropic Layer] The optically anisotropic layer of the optical film of the present invention is a layer provided adjacent to the support described above, and in the present invention, is a layer formed using an optically anisotropic layer-forming composition containing a polymerizable liquid crystal compound. More specifically, as will be described in detail in the optically anisotropic layer-forming step of the optically anisotropic layer manufacturing method of the present invention described later, it is preferable that the layer is formed by aligning the polymerizable liquid crystal compound in the coating film formed by applying the optically anisotropic layer-forming composition and fixing that state, and in this case, it is no longer necessary for the layer to exhibit liquid crystallinity.

[0034] <Polymerizable Liquid Crystal Compound> The polymerizable liquid crystal compound contained in the composition for forming an optically anisotropic layer is a liquid crystal compound having a polymerizable group. The polymerizable group is not particularly limited, but is preferably a radically or cationic polymerizable group. The radically polymerizable group may be a known radically polymerizable group, and preferred examples include an acryloyloxy group or a methacryloyloxy group. In this case, the acryloyloxy group is generally known to have a faster polymerization rate, and from the viewpoint of improving productivity, an acryloyloxy group is preferred, but a methacryloyloxy group can also be used as the polymerizable group. The cationic polymerizable group may be a known cationic polymerizable group, and specific examples include an alicyclic ether group, a cyclic acetal group, a cyclic lactone group, a cyclic thioether group, a spiro orthoester group, and a vinyloxy group. Among these, an alicyclic ether group or a vinyloxy group is preferred, and an epoxy group, an oxetanyl group, or a vinyloxy group is particularly preferred. Particularly preferred examples of the polymerizable group include polymerizable groups represented by any one of the following formulae (P-1) to (P-20).

[0035]

[0036] The polymerizable liquid crystal compound is not particularly limited, and examples thereof include compounds capable of aligning in any of the following modes: homeotropic alignment, homogeneous alignment, twist alignment, hybrid alignment, and cholesteric alignment. Generally, liquid crystal compounds can be classified into rod-shaped and discotic types based on their shape. Furthermore, each type can be divided into low-molecular-weight and high-molecular-weight types. A high-molecular-weight compound generally refers to a compound with a degree of polymerization of 100 or more (see "Polymer Physics: Phase Transition Dynamics," by Masao Doi, p. 2, Iwanami Shoten, 1992). While any liquid crystal compound can be used in the present invention, rod-shaped or discotic liquid crystal compounds (discotic liquid crystal compounds) are preferred. Furthermore, liquid crystal compounds that are monomers or have a relatively low molecular weight and a degree of polymerization of less than 100 are preferred.

[0037] As the rod-shaped liquid crystal compound, for example, those described in claim 1 of JP-A-11-513019 or paragraphs

[0026] to

[0098] of JP-A-2005-289980 are preferred, and as the discotic liquid crystal compound, those described in paragraphs

[0020] to

[0067] of JP-A-2007-108732 or paragraphs

[0013] to

[0108] of JP-A-2010-244038 are preferred.

[0038] As the polymerizable liquid crystal compound, a liquid crystal compound having reverse wavelength dispersion can be used. Here, in this specification, the term "reverse wavelength dispersion" refers to a liquid crystal compound that, when the in-plane retardation (Re) value of a retardation film produced using the compound is measured at a specific wavelength (visible light range), has a constant or higher Re value as the measured wavelength increases.

[0039] The reverse wavelength dispersion liquid crystal compound is not particularly limited as long as it can form a reverse wavelength dispersion film as described above, and examples thereof include compounds represented by the general formula (I) described in JP-A-2008-297210 (particularly, the compounds described in paragraphs

[0034] to

[0039] ), compounds represented by the general formula (1) described in JP-A-2010-084032 (particularly, the compounds described in paragraphs

[0067] to

[0073] ), and compounds represented by the general formula (1) described in JP-A-2016-081035 (particularly, the compounds described in paragraphs

[0043] to

[0055] ). Further, JP-A-2011-006360, paragraphs

[0027] to

[0100] , JP-A-2011-006361, paragraphs

[0028] to

[0125] , JP-A-2012-207765, paragraphs

[0034] to

[0298] , JP-A-2012-077055, paragraphs

[0016] to

[0345] , WO12 / 141245, paragraphs

[0017] to

[0072] , WO12 / 147904, paragraphs

[0021] to

[0088] , and WO14 / 147904, paragraphs

[0028] to

[0115] of the compounds described in.

[0040] <Polymerization initiator> The composition for forming an optically anisotropic layer preferably contains a polymerization initiator. Examples of the polymerization initiator include those described above in connection with the composition for forming an alignment film.

[0041] <Solvent> The composition for forming an optically anisotropic layer preferably contains a solvent from the viewpoint of workability when forming an optically anisotropic layer. Examples of the solvent include ketones (e.g., acetone, 2-butanone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone), ethers (e.g., dioxane and tetrahydrofuran), aliphatic hydrocarbons (e.g., hexane), alicyclic hydrocarbons (e.g., cyclohexane), aromatic hydrocarbons (e.g., toluene, xylene, and trimethylbenzene), halogenated carbons (e.g., dichloromethane, dichloroethane, dichlorobenzene, and chlorotoluene), esters (e.g., methyl acetate, ethyl acetate, and butyl acetate), water, alcohols (e.g., ethanol, isopropanol, butanol, and cyclohexanol), cellosolves (e.g., methyl cellosolve and ethyl cellosolve), cellosolve acetates, sulfoxides (e.g., dimethyl sulfoxide), and amides (e.g., dimethylformamide and dimethylacetamide).

[0042] <Leveling Agent> The composition for forming an optically anisotropic layer preferably contains a leveling agent from the viewpoint of maintaining a smooth surface of the optically anisotropic layer and facilitating alignment control. As such a leveling agent, a fluorine-based leveling agent or a silicon-based leveling agent is preferred because of its high leveling effect relative to the amount added, and a fluorine-based leveling agent is more preferred because it is less likely to cause bleeding (bloom, bleed). Examples of the leveling agent include the compounds described in paragraphs

[0079] to

[0102] of JP-A No. 2007-069471, the compounds represented by general formula (I) described in JP-A No. 2013-047204 (particularly the compounds described in paragraphs

[0020] to

[0032] ), and the compounds represented by general formula (I) described in JP-A No. 2012-211306 (particularly the compounds described in paragraphs

[0022] to

[0029] ). Examples of the leveling agent include compounds described above, liquid crystal alignment promoters represented by general formula (I) described in JP-A-2002-129162 (particularly the compounds described in paragraphs

[0076] to

[0078] and

[0082] to

[0084] ), and compounds represented by general formulas (I), (II) and (III) described in JP-A-2005-099248 (particularly the compounds described in paragraphs

[0092] to

[0096] ). The leveling agent may also function as an alignment control agent, which will be described later.

[0043] <Alignment Control Agent> The composition for forming an optically anisotropic layer may contain an alignment control agent, if necessary. The alignment control agent can form various alignment states such as homogeneous alignment, homeotropic alignment, tilted alignment, twisted alignment, hybrid alignment, and cholesteric alignment, and can also realize specific alignment states more uniformly and more precisely controlled.

[0044] As the alignment control agent for promoting homogeneous alignment, for example, a low molecular weight alignment control agent and a high molecular weight alignment control agent can be used. For low molecular weight alignment control agents, for example, the descriptions in paragraphs

[0009] to

[0083] of JP 2002-20363 A, paragraphs

[0111] to

[0120] of JP 2006-106662 A, and paragraphs

[0021] to

[0029] of JP 2012-211306 A can be referred to, the contents of which are incorporated herein by reference. Furthermore, for polymer orientation control agents, reference can be made to, for example, paragraphs

[0021] to

[0057] of JP-A No. 2004-198511 and paragraphs

[0121] to

[0167] of JP-A No. 2006-106662, the contents of which are incorporated herein by reference.

[0045] Examples of alignment control agents that form or promote homeotropic alignment include boronic acid compounds and onium salt compounds. Examples of such alignment control agents include the compounds described in paragraphs

[0023] to

[0032] of JP 2008-225281 A, paragraphs

[0052] to

[0058] of JP 2012-208397 A, paragraphs

[0024] to

[0055] of JP 2008-026730 A, and paragraphs

[0043] to

[0055] of JP 2016-193869 A, the contents of which are incorporated herein by reference.

[0046] On the other hand, cholesteric alignment can be achieved by adding a chiral agent to the composition for forming an optically anisotropic layer, and the direction of rotation of the cholesteric alignment can be controlled by the direction of the chirality. The pitch of the cholesteric alignment may be controlled depending on the alignment control force of the chiral agent.

[0047] When the composition for forming an optically anisotropic layer contains an alignment control agent, the content of the alignment control agent is preferably 0.01 to 10 mass %, more preferably 0.05 to 5 mass %, based on the total mass of solids in the composition. When the content is within this range, a desired alignment state is achieved, while precipitation, phase separation, alignment defects, etc. are suppressed, and a uniform and highly transparent cured product can be obtained.

[0048] <Other Components> The composition for forming an optically anisotropic layer may contain other components in addition to the components described above. Examples of the other components include a surfactant, a tilt angle control agent, an alignment aid, a plasticizer, and a crosslinking agent.

[0049] The optically anisotropic layer is a film formed using the above-mentioned composition for forming an optically anisotropic layer, and the manufacturing procedure thereof will be described in detail later in the optically anisotropic layer forming step of the manufacturing method of the optical film of the present invention.

[0050] The thickness of the optically anisotropic layer is not particularly limited, but from the viewpoint of making the device thinner, it is preferably 0.7 to 2.5 μm, more preferably 0.9 to 2.2 μm.

[0051] The orientation state of the polymerizable liquid crystal compound in the optically anisotropic layer may be any of homogeneous orientation (horizontal orientation), homeotropic orientation (vertical orientation), tilted orientation, and twisted orientation. Among these, the optically anisotropic layer is preferably a layer in which the polymerizable liquid crystal compound is fixed in a homogeneous or twisted orientation state, because this improves the alignment of the liquid crystal compound in the optically anisotropic layer. In this specification, "homogeneous orientation" refers to a state in which the major surface of the optically anisotropic layer and the long axis direction of the polymerizable liquid crystal compound are parallel. Strict parallelism is not required, and in this specification, it refers to an orientation in which the angle between the long axis direction of the polymerizable liquid crystal compound and the major surface of the optically anisotropic layer is less than 10°. In the optically anisotropic layer, the angle between the long axis direction of the polymerizable liquid crystal compound and the major surface of the optically anisotropic layer is preferably 0 to 5°, more preferably 0 to 3°, and even more preferably 0 to 2°.

[0052] The optically anisotropic layer is more preferably a positive A plate or a positive C plate, and even more preferably a positive A plate.

[0053] Here, a positive A plate (positive A plate) and a positive C plate (positive C plate) are defined as follows. When the refractive index in the in-plane slow axis direction of the film (the direction in which the in-plane refractive index is maximum) is nx, the refractive index in the in-plane direction perpendicular to the in-plane slow axis is ny, and the refractive index in the thickness direction is nz, a positive A plate satisfies the relationship of formula (A1), and a positive C plate satisfies the relationship of formula (C1). Note that a positive A plate has a positive Rth, and a positive C plate has a negative Rth. Formula (A1) nx>ny≒nz Formula (C1) nz>nx≒ny Note that the above "≒" encompasses not only the case where both are completely identical, but also the case where both are substantially identical. Regarding "substantially the same," for a positive A plate, "ny ≒ nz" includes, for example, a case where (ny - nz) x d (where d is the film thickness) is -10 to 10 nm, preferably -5 to 5 nm, and "nx ≒ nz" includes, for example, a case where (nx - nz) x d (where d is the film thickness) is -10 to 10 nm, preferably -5 to 5 nm. Also, for a positive C plate, "nx ≒ ny" includes, for example, a case where (nx - ny) x d (where d is the film thickness) is 0 to 10 nm, preferably 0 to 5 nm.

[0054] When the optically anisotropic layer is a positive A plate, from the viewpoint of functioning as a λ / 4 plate, Re(550) is preferably 100 to 180 nm, more preferably 120 to 160 nm, even more preferably 130 to 150 nm, and particularly preferably 130 to 145 nm. Here, the "λ / 4 plate" is a plate having a λ / 4 function, specifically, a plate having a function of converting linearly polarized light of a certain wavelength into circularly polarized light (or circularly polarized light into linearly polarized light).

[0055] [Method for producing optical film] The method for producing an optical film of the present invention comprises a support preparation step of preparing a support containing the above-mentioned specific surfactant, a rubbing step of subjecting the support to a rubbing treatment, and an optically anisotropic layer formation step of forming an optically anisotropic layer on the rubbed support using an optically anisotropic layer-forming composition containing a polymerizable liquid crystal compound. The procedure of each step will be described in detail below.

[0056] [Support Preparation Step] The support preparation step is a step of preparing a support containing the specific surfactant described above. Here, the support prepared in this step is the support described above as the support included in the optical film of the present invention.

[0057] The method for preparing the support is not particularly limited, and may be, for example, a method including a step of casting a dope containing the specific surfactant described above. Note that the method for preparing and casting the dope may be any conventionally known method, except for blending the specific surfactant into the dope.

[0058] Another method for preparing the support includes a method comprising a step of impregnating the surface of a polymer film with a composition containing the specific surfactant and a solvent. Examples of the solvent used together with the specific surfactant include the solvents described in the optically anisotropic layer-forming composition. The solvent used can be appropriately selected depending on the properties of the substrate, such as the ease of impregnation. Examples of the polymer film include the same polymer films as those described in the support of the optical film of the present invention, and cellulose acylate films are particularly preferred. The method for impregnating the polymer film with the composition is not particularly limited, and examples include coating methods, such as wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating.

[0059] [Rubbing Step] The rubbing step is a step of subjecting a support containing the specific surfactant described above to a rubbing treatment. Here, the rubbing treatment can be a treatment method that is widely used as a liquid crystal alignment treatment step for liquid crystal display devices. That is, a method is used in which the surface of the alignment film is rubbed in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber, or the like to obtain alignment.

[0060] [Optically Anisotropic Layer Forming Step] The optically anisotropic layer forming step is a step of forming an optically anisotropic layer on a support that has been subjected to a rubbing treatment, using a composition for forming an optically anisotropic layer.

[0061] One specific example of a procedure for forming an optically anisotropic layer is a method in which an optically anisotropic layer-forming composition is applied to a support, a coating film is formed on the support, the polymerizable liquid crystal compound in the coating film is aligned, and then the coating film is cured to form an optically anisotropic layer. Examples of methods for applying the optically anisotropic layer-forming composition to a support include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. After applying the optically anisotropic layer-forming composition to the support, if necessary, the support coated with the optically anisotropic layer-forming composition may be dried to remove the solvent.

[0062] The method for orienting the polymerizable liquid crystal compound in the coating film (orientation treatment) is not particularly limited, and examples include a method of heating the coating film and a method of drying the coating film at room temperature. In the case of a thermotropic liquid crystal compound, the liquid crystal phase formed by the orientation treatment can generally be transitioned by a change in temperature. In the case of a lyotropic liquid crystal compound, the transition can also be caused by changing the composition ratio, such as the amount of solvent. The conditions for heating the coating film are not particularly limited, but the heating temperature is preferably 50 to 150°C, and the heating time is preferably 10 seconds to 5 minutes.

[0063] Next, the coating film in which the polymerizable liquid crystal compound is aligned is subjected to a curing treatment to form an optically anisotropic layer. The curing method is not particularly limited, and examples thereof include light irradiation treatment and heat treatment, with light irradiation being preferred. The type of light used for exposure is not particularly limited, but ultraviolet light is preferred. The exposure dose is not particularly limited, and is 10 mJ / cm. ２ ~50 J / cm ２ is preferred, and 20 mJ / cm ２ ~5 J / cm ２ In order to promote the polymerization reaction, the reaction may be carried out under heating conditions.

[0064] [Polarizing Plate] The polarizing plate of the present invention is a polarizing plate having the optical film of the present invention and a polarizer.

[0065] [Polarizer] The polarizer of the polarizing plate of the present invention is not particularly limited as long as it has the function of converting light into specific linearly polarized light, and conventionally known absorptive polarizers and reflective polarizers can be used. Examples of absorptive polarizers include iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers include coated polarizers and stretched polarizers, and either type can be used. However, polarizers produced by adsorbing iodine or a dichroic dye onto polyvinyl alcohol and stretching the resulting film are preferred. Furthermore, methods for obtaining polarizers by stretching and dyeing a laminated film having a polyvinyl alcohol layer formed on a substrate are described in Japanese Patent Nos. 5,048,120, 5,143,918, 4,691,205, 4,751,481, and 4,751,486. These known techniques related to polarizers can also be preferably used. Examples of coated polarizers include those disclosed in WO2018 / 124198, WO2018 / 186503, WO2019 / 132020, WO2019 / 132018, WO2019 / 189345, JP2019-197168A, JP2019-194685A, and JP2019-139222A, and known techniques relating to these polarizers can also be preferably utilized. Examples of reflective polarizers that can be used include polarizers in which thin films with different birefringences are laminated, wire grid polarizers, and polarizers in which a cholesteric liquid crystal having a selective reflection region is combined with a quarter-wave plate. Among these, polyvinyl alcohol-based resins (-CH ２A polymer containing -CHOH- as a repeating unit. In particular, a polarizer containing at least one selected from the group consisting of polyvinyl alcohol and an ethylene-vinyl alcohol copolymer is preferred. Furthermore, from the viewpoint of imparting crack resistance, the polarizer may have depolarizing portions formed along opposing edges. Examples of depolarizing portions include those described in JP 2014-240970 A. The polarizer may also have non-polarizing portions arranged at predetermined intervals in the longitudinal direction and / or width direction. The non-polarizing portions are partially bleached portions. The arrangement pattern of the non-polarizing portions can be appropriately set depending on the purpose. For example, when the polarizer is cut (cut, punched, etc.) to a predetermined size for installation in an image display device of a predetermined size, the non-polarizing portions are arranged in positions corresponding to the camera portion of the image display device. Examples of arrangement patterns of non-polarizing portions include those described in JP 2016-27392 A.

[0066] The thickness of the polarizer is not particularly limited, but is preferably from 3 to 60 μm, more preferably from 3 to 30 μm, and even more preferably from 3 to 10 μm.

[0067] The polarizing plate of the present invention may include, in addition to the optical film and polarizer of the present invention, other optical films, a protective film (described later), and other functional layers. The function of the functional layer is not particularly limited, and may be, for example, a layer having a function such as an adhesive layer, a stress relaxation layer, a planarizing layer, an antireflection layer, a refractive index adjustment layer, or an ultraviolet absorbing layer. The protective film may be used on both sides of the polarizer, or on only one side of the polarizer. When the protective film is located on the same side as the optical film of the present invention, it may be disposed between the polarizer and the optical film, or on the opposite side of the optical film from the polarizer, via a pressure-sensitive adhesive or adhesive. When the optically anisotropic layer of the optical film of the present invention described above or the optically anisotropic layer of the present invention is a λ / 4 plate (positive A plate), the polarizing plate can be used as a circular polarizing plate. When the polarizing plate is used as a circular polarizing plate, the optically anisotropic layer described above is a λ / 4 plate (positive A plate), and the angle between the slow axis of the λ / 4 plate and the absorption axis of the polarizer described below is preferably 30 to 60°, more preferably 40 to 50°, even more preferably 42 to 48°, and particularly preferably 45°. Here, the "slow axis" of the λ / 4 plate refers to the direction in which the refractive index is maximized in the plane of the λ / 4 plate, and the "absorption axis" of the polarizer refers to the direction in which the absorbance is highest. The polarizing plate can also be used as an optical compensation film for an IPS (In-Plane-Switching) or FFS (Fringe-Field-Switching) liquid crystal display device. When the polarizing plate is used as an optical compensation film for an IPS-mode or FFS-mode liquid crystal display device, the above-mentioned optically anisotropic layer is preferably used as at least one plate of a laminate of a positive A plate and a positive C plate, and the angle between the slow axis of the positive A plate layer and the absorption axis of the polarizer is preferably orthogonal or parallel, more preferably 0 to 5° or 85 to 95°. Furthermore, when the optical compensation film is formed by laminating a polarizer, a positive C plate, and a positive A plate in this order, it is more preferable that the angle between the slow axis of the positive A plate and the absorption axis of the polarizer is parallel.Similarly, when the optical compensation film has a polarizer, a positive A plate, and a positive C plate laminated in this order, it is more preferable that the angle between the slow axis of the positive A plate and the absorption axis of the polarizer is perpendicular. When the polarizing plate of the present invention is used in a liquid crystal display device described below, it is preferable that the angle between the slow axis of the optically anisotropic layer and the absorption axis of the polarizer is parallel or perpendicular. In this specification, "parallel" does not require strict parallelism, but means that the angle between one and the other is less than 10°. In this specification, "orthogonal" does not require strict perpendicularity, but means that the angle between one and the other is more than 80° and less than 100°.

[0068] [Protective Film] The material of the protective film is not particularly limited, and examples thereof include the same polymer films as those described for the support of the optical film of the present invention, and among these, it is preferable to use a cellulose acylate film.

[0069] The optical properties of the protective film are not particularly limited, but when the protective film is located on the same side as the optical film of the present invention, it is preferable that the following formulas are satisfied: 0 nm≦Re(550)≦10 nm −40 nm≦Rth(550)≦40 nm.

[0070] [Adhesive Layer] In the polarizing plate, an adhesive layer may be disposed between the optical film of the present invention and the polarizer. Examples of materials for forming the adhesive layer include members formed of substances having a ratio of storage modulus G' to loss modulus G" (tan δ = G" / G') measured with a dynamic viscoelasticity measuring device of 0.001 to 1.5, and include so-called adhesives and substances that tend to creep. Examples of adhesives include, but are not limited to, polyvinyl alcohol-based adhesives.

[0071] [Adhesive Layer] The polarizing plate may have an adhesive layer disposed between the optical film of the present invention and the polarizer. The adhesive layer is preferably a curable adhesive composition that cures upon irradiation with active energy rays or heating. Examples of curable adhesive compositions include curable adhesive compositions containing a cationically polymerizable compound and curable adhesive compositions containing a radically polymerizable compound. The thickness of the adhesive layer is preferably 0.01 to 20 μm, more preferably 0.01 to 10 μm, and even more preferably 0.05 to 5 μm. When the thickness of the adhesive layer is within this range, lifting or peeling does not occur between the laminated protective layer or optically anisotropic layer and the polarizer, and practically acceptable adhesive strength is obtained. Furthermore, from the viewpoint of suppressing the generation of bubbles, the thickness of the adhesive layer is preferably 0.4 μm or more. Furthermore, from the viewpoint of durability, the bulk water absorption of the adhesive layer may be adjusted to 10% by mass or less, preferably 2% by mass or less. The bulk water absorption is measured in accordance with the water absorption test method described in JIS K 7209. For the adhesive layer, reference can be made to, for example, paragraphs

[0062] to

[0080] of JP 2016-35579 A, ​​the contents of which are incorporated herein by reference.

[0072] [Easy-Adhesion Layer] The polarizing plate may have an easy-adhesion layer disposed between the optical film of the present invention and the polarizer. From the viewpoint of excellent adhesion between the optical film of the present invention and the polarizer and further suppressing the occurrence of cracks in the polarizer, the easy-adhesion layer should have a storage modulus at 85°C of 1.0 × 10 ６ Pa ~ 1.0 x 10 ７ Pa is preferable. Constituent materials of the easy-adhesion layer include polyolefin-based components and polyvinyl alcohol-based components. The thickness of the easy-adhesion layer is preferably 500 nm to 1 μm. For the easy-adhesion layer, for example, paragraphs

[0048] to

[0053] of JP 2018-36345 A can be referred to, and the contents of these can be incorporated into the present specification.

[0073] [Image Display Device] The image display device of the present invention is an image display device having the optical film of the present invention or the optically anisotropic layer of the present invention. The display element used in the image display device is not particularly limited, and examples thereof include a liquid crystal cell, an organic electroluminescence (hereinafter abbreviated as "EL (Electro Luminescence)") display panel, and a plasma display panel. Of these, a liquid crystal cell and an organic EL display panel are preferred, and a liquid crystal cell is more preferred. That is, as the image display device, a liquid crystal display device using a liquid crystal cell as the display element or an organic EL display device using an organic EL display panel as the display element is preferred, and a liquid crystal display device is more preferred.

[0074] [Liquid Crystal Display Device] A liquid crystal display device, which is an example of an image display device, is a liquid crystal display device having the above-described polarizing plate and a liquid crystal cell. Of the polarizing plates provided on both sides of the liquid crystal cell, it is preferable to use the above-described polarizing plate as the front-side polarizing plate, and it is more preferable to use the above-described polarizing plate as the front-side and rear-side polarizing plates. The liquid crystal cell constituting the liquid crystal display device will be described in detail below.

[0075] <Liquid Crystal Cell> The liquid crystal cell used in the liquid crystal display device is preferably, but not limited to, a VA (Vertical Alignment) mode, an OCB (Optically Compensated Bend) mode, an IPS (In-Plane-Switching) mode, an FFS (Fringe-Field-Switching) mode, or a TN (Twisted Nematic) mode. In a TN mode liquid crystal cell, when no voltage is applied, the rod-shaped liquid crystal molecules are aligned substantially horizontally and further twisted at an angle of 60 to 120 degrees. TN mode liquid crystal cells are most commonly used in color TFT liquid crystal displays and are described in numerous literature. In a VA mode liquid crystal cell, the rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied. VA mode liquid crystal cells include (1) narrowly defined VA mode liquid crystal cells in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied and substantially horizontally when a voltage is applied (described in Japanese Patent Application Laid-Open No. 2-176625), (2) multi-domain VA mode liquid crystal cells (described in SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845) in order to widen the viewing angle (MVA mode liquid crystal cells), (3) n-ASM mode liquid crystal cells in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied and substantially horizontally when a voltage is applied (described in Proceedings of the Japan Liquid Crystal Symposium 58-59 (1998)), and (4) SURVIVAL mode liquid crystal cells (announced at LCD International 98). Furthermore, VA-mode liquid crystal cells may be any of PVA (Patterned Vertical Alignment) type, optical alignment type, and PSA (Polymer-Sustained Alignment) type. Details of these modes are described in Japanese Patent Application Laid-Open No. 2006-215326 and Japanese Patent Application Laid-Open No. 2008-538819. In IPS-mode liquid crystal cells, rod-shaped liquid crystal molecules are aligned substantially parallel to the substrates, and the liquid crystal molecules respond in a planar manner when an electric field parallel to the substrate surface is applied. In IPS-mode cells, black is displayed when no electric field is applied, and the absorption axes of a pair of upper and lower polarizing plates are perpendicular to each other.Methods of using an optical compensation sheet to reduce light leakage in oblique directions during black display and improve the viewing angle are disclosed in JP-A Nos. 10-54982, 11-202323, 9-292522, 11-133408, 11-305217, and 10-307291.

[0076] [Organic EL Display Device] An example of an organic EL display device, which is an example of an image display device, includes, from the viewing side, a polarizer, a λ / 4 plate (positive A plate) made of the above-mentioned optically anisotropic layer, and an organic EL display panel, in this order. The organic EL display panel is a display panel configured using organic EL elements in which an organic light-emitting layer (organic electroluminescence layer) is sandwiched between electrodes (between a cathode and an anode). The configuration of the organic EL display panel is not particularly limited, and a known configuration may be used.

[0077] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0078] [Example 1] [Preparation of Cellulose Acylate Film (Support)] A cellulose acylate dope having the following composition was placed in a mixing tank, stirred, and heated at 90°C for 10 minutes. The resulting composition was then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare a dope. The solid content of the dope was 23.5% by mass, the amount of plasticizer added was the ratio relative to the cellulose acylate, and the solvent for the dope was methylene chloride / methanol / butanol = 81 / 18 / 1 (mass ratio).

[0079] ----------------------------------------------- Cellulose acylate dope ------------------------------------------------ Cellulose acylate (acetyl substitution degree 2.86, viscosity average degree of polymerization 310) 100 parts by mass Sugar ester compound 1 (shown in chemical formula (S4)) 6.0 parts by mass Sugar ester compound 2 (shown in chemical formula (S5)) 2.0 parts by mass Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by mass Sodium dodecyl sulfate 0.75 parts by mass Solvent (methylene chloride / methanol / butanol) ------------------------------------------------

[0080]

[0081] The dope prepared above was cast using a drum film-forming machine. Specifically, the dope was cast from a die onto a metal support cooled to 0°C, and then the resulting web (film) was peeled off. The drum was made of SUS (stainless used steel). Next, the cast web (film) was peeled off from the drum and dried for 20 minutes in a tenter apparatus at 30 to 40°C, using a tenter apparatus in which both ends of the web were clipped during film transport. Subsequently, the web was post-dried by zone heating while being transported by a roll. Next, the resulting web was knurled, and then a winding support S-1 was produced.

[0082] [Formation of Optically Anisotropic Layer] The roll support S-1 prepared above was continuously subjected to rubbing treatment. At this time, the longitudinal direction of the long film was parallel to the transport direction, and the angle between the film longitudinal direction (transport direction) and the rotation axis of the rubbing roller was 80°. The film longitudinal direction (transport direction) was set to 90°, and when observed from the film side, the film width direction was used as the reference (0°) and clockwise directions were expressed as positive values, so the rotation axis of the rubbing roller was at an angle of 10°. In other words, the position of the rotation axis of the rubbing roller was rotated 80° counterclockwise with the film longitudinal direction as the reference.

[0083] Using the rubbed cellulose acylate film as a support, an optically anisotropic layer-forming composition (1) containing a rod-shaped liquid crystal compound having the following composition was applied using a Giesser coater to form a composition layer. The resulting composition layer was then heated at 80°C for 60 seconds. This heating caused the rod-shaped liquid crystal compound in the composition layer to align in a predetermined direction. Thereafter, the composition layer was irradiated with ultraviolet light (irradiation dose: 35 mJ / cm) using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) at 30°C in oxygen-containing air (oxygen concentration: approximately 20% by volume). ２ Subsequently, the obtained composition layer was heated at 80°C for 10 seconds. After that, nitrogen purging was performed to adjust the oxygen concentration to 100 ppm by volume, and the composition layer was irradiated with ultraviolet light (irradiation dose: 500 mJ / cm) using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 80°C. ２ ), an optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed. In this way, an optical film (F-1) was produced.

[0084] ------------------------------------------------ Composition for forming optically anisotropic layer (1) -------------------------------------------------- Rod-shaped liquid crystal compound (A) below: 80 parts by mass Rod-shaped liquid crystal compound (B) below: 17 parts by mass Polymerizable compound (C) below: 3 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by BASF) 3 parts by mass Left-handed twisted chiral agent (L2) below: 0.46 parts by mass Right-handed twisted chiral agent (R2) below: 0.41 parts by mass Polymer (A) below: 0.08 parts by mass Polymer (B) below: 0.38 parts by mass Methyl isobutyl ketone 117 parts by mass・Ethyl propionate 23 parts by mass ・Cyclohexane 16 parts by mass

[0085] Rod-like liquid crystal compound (A) [a mixture of the following liquid crystal compounds (RA), (RB), and (RC) in a mass ratio of 84:14:2]

[0086] Rod-shaped liquid crystal compound (B)

[0087] Polymerizable compound (C)

[0088] Left-twisted chiral agent (L2)

[0089] Right-twisted chiral agent (R2)

[0090] Polymer (A) [fluorine part: 39% by mass, mesogen part: 61% by mass]

[0091] Polymer (B) (wherein the numerical value for each repeating unit represents the content (% by mass) of each repeating unit relative to all repeating units.)

[0092] The optical film (F-1) prepared above was cut parallel to the rubbing direction, and the optically anisotropic layer was observed from the cross-sectional direction using a polarizing microscope. The thickness of the optically anisotropic layer was 2.7 μm, and the region (second region) with a thickness (d2) of 1.3 μm on the substrate side of the optically anisotropic layer was homogeneously aligned without a twist angle, and the region (first region) with a thickness (d1) of 1.4 μm on the air side (opposite the substrate) of the optically anisotropic layer was twistedly aligned. The optical properties of the optical film (F-1) were determined using an Axoscan from Axometrics and their analysis software (Multi-Layer Analysis). The product of Δn2 and the thickness d2 of the second region at a wavelength of 550 nm (Δn2d2) was 173 nm, the twist angle of the liquid crystal compound was 0°, and the alignment axis angles of the liquid crystal compound relative to the longitudinal direction were −10° on the side in contact with the substrate and −10° on the side in contact with the first region. Furthermore, the product of Δn1 and the thickness d1 of the first region at a wavelength of 550 nm (Δn1d1) was 184 nm, the twist angle of the liquid crystal compound was 75°, and the alignment axis angles of the liquid crystal compound relative to the longitudinal direction were −10° on the side in contact with the second region and −85° on the air side.

[0093] Examples 2 to 13 and Comparative Examples 1 to 3 Optical films were produced in the same manner as in Example 1, except that the type and amount of surfactant added was changed as shown in Table 1 below. Comparative Example 1 is an example in which no surfactant was added, and is indicated by "-" in Table 1 below. The structures of Copolymer A, Copolymer B, and Copolymer C used as surfactants in Examples 11 to 13 are as follows:

[0094] Copolymer A

[0095] Copolymer B

[0096] Copolymer C

[0097] [Example 14] An optical film was produced in the same manner as in Example 2, except that the composition for forming an optically anisotropic layer (1) was changed to the composition for forming an optically anisotropic layer (2) shown below, and the optically anisotropic layer was formed under the following conditions.

[0098] ------------------------------------------------ Optically anisotropic layer-forming composition (2)---------------------------------------------------------------- Rod-shaped liquid crystal compound (A) 80 parts by mass Rod-shaped liquid crystal compound (B) 17 parts by mass Polymerizable compound (C) 3 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by BASF) 3 parts by mass Left-handed twisted chiral agent (L2) 0.46 parts by mass Right-handed twisted chiral agent (R2) 0.41 parts by mass Polymer (A) 0.08 parts by mass o-xylene 156 parts by mass----------------------------------------------------------------

[0099] Example 15 An optical film was produced in the same manner as in Example 1, except that a surfactant (sodium dodecyl sulfate) was not added to the cellulose acylate dope, and that the following surfactant-containing composition was applied with a #8 bar and then dried at 80°C for 1 minute before rubbing treatment. ------------------------------------------------ Surfactant-containing composition ------------------------------------------------ Sodium dodecyl sulfate 0.5 parts by mass Isopropyl alcohol 90.0 parts by mass Water 10.0 parts by mass

[0100] Example 16 An optical film was produced in the same manner as in Example 2, except that the optically anisotropic layer-forming composition (1) was replaced with the optically anisotropic layer-forming composition (3) shown below, and the position of the rotation axis of the rubbing roller was changed from -10° to +12.5°. The thickness of the obtained optically anisotropic layer was 1.0 μm. The average tilt angle of the long axes of the rod-shaped liquid crystal compounds with respect to the film plane was 0°, confirming that the liquid crystal compounds were aligned horizontally with respect to the film plane. The angle of the slow axis was -77.5°, when perpendicular to the rotation axis of the rubbing roller and the film width direction was taken as 0° (the film longitudinal direction is 90°, and the clockwise direction with respect to the film width direction when observed from the optically anisotropic layer C side is represented as a positive value). The in-plane retardation of the optically anisotropic layer at a wavelength of 550 nm was 116 nm, and the optically anisotropic layer exhibited forward wavelength dispersion.

[0101] ------------------------------------------------ Composition for forming optically anisotropic layer (3)------------------------------------------------ Rod-like liquid crystal compound (A) 100 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 6 parts by mass Fluorine-containing compound (F-1) below 0.25 parts by mass Fluorine-containing compound (F-2) below 0.1 parts by mass Ethylene oxide-modified trimethylol propane triacrylate 4 parts by mass Methyl isobutyl ketone 337 parts by mass------------------------------------------------

[0102] Fluorine-containing compound (F-1)

[0103] Fluorine-containing compound (F-2)

[0104] [Comparative Example 4] An optical film was produced in the same manner as in Example 1, except that the roll-up support S-1 was replaced with A4160 (one-sided easy-adhesion type, thickness 50 μm) manufactured by Toyobo Co., Ltd.

[0105] Comparative Example 5 A 58 μm thick (meth)acrylic resin film having a lactone ring structure and having an easy-adhesion layer on one side was produced in the same manner as in Example 4 of JP 2012-93703 A. An optical film was produced in the same manner as in Example 1, except that the (meth)acrylic resin film produced above was used instead of the winding support S-1.

[0106] [Evaluation] The prepared optical films were evaluated as follows. The results are shown in Table 1 below. Furthermore, the prepared optical films were analyzed for components in the depth direction using a time-of-flight secondary ion mass spectrometer (TOF-SIMS) ("SIMS5" manufactured by IONTOF). The analysis confirmed that, for the optical films prepared in Examples 1 to 16 and Comparative Examples 2, 3, and 5, a surfactant was present in the region of the support from the surface on the optically anisotropic layer side to 10% of the support thickness, while for the optical films prepared in Comparative Examples 1 and 4, a surfactant was not present in the support. Furthermore, the component analysis confirmed that, for the optical films prepared in Examples 1 to 16 and Comparative Examples 1 to 3, the optically anisotropic layer and the support were adjacent to each other, while for the optical films prepared in Comparative Examples 4 and 5, an easy-adhesion layer was present between the optically anisotropic layer and the support.

[0107] [Dynamic Friction Coefficient] A 100 g load was applied to the surface of the support, and a stainless steel ball was rolled over it, and the load applied was measured to determine the dynamic friction coefficient.

[0108] [Orientation] The optically anisotropic layer in the obtained optical film was observed at random in 10 visual fields (visual field size 1715 × 1280 μm) at 50x magnification under a polarizing microscope in a crossed Nicol position, and each visual field was classified into the following three categories. I: No optical defects were observed. II: Slight optical defects were observed, but at a level that poses no practical problems. III: Many optical defects were observed, at a level that poses practical problems. The 10 visual fields were evaluated using the following five-point scale. A: All 10 visual fields were I or II, with 0 to 2 II visual fields. B: All 10 visual fields were I or II, with 3 to 5 II visual fields. C: All 10 visual fields were I or II, with 6 to 10 II visual fields. D: III was included in 10 visual fields, and 1 to 5 III visual fields. E: III was included in 10 visual fields, and 6 to 10 III visual fields.

[0109] [Bright Spot Defects] Two polarizing plates were stacked on a light box in a crossed Nicol position, and the obtained optical film (observation area: 1 × 1 m) was sandwiched between the two polarizing plates, and light was transmitted through the light box. The optical film was observed from above the polarizing plate using a magnifying glass, and defects with a diameter of 100 μm or more were marked. A cross section was cut with a microtome so as to pass through the center of the marked defects, and observation was performed under an optical microscope from the cross-sectional direction. The number of defects in which foreign matter was observed in the optically anisotropic layer was counted and evaluated according to the following criteria. Note that the optical films produced in Comparative Examples 4 and 5 were deemed unevaluable due to poor orientation, which made it impossible to accurately evaluate bright spot defects, and are indicated by "-" in Table 1 below. A: 2 or less defects B: 3 to 4 defects C: 5 to 8 defects D: 8 to 20 defects E: 21 or more defects

[0110]

[0111] The results shown in Table 1 indicate that when the support did not contain a specific surfactant or when a surfactant other than the specific surfactant was contained, the alignment of the liquid crystal compound in the optically anisotropic layer was good, but the occurrence of bright spot defects could not be suppressed (Comparative Examples 1 to 3). Furthermore, when the support and the optically anisotropic layer were not adjacent, the alignment of the liquid crystal compound in the optically anisotropic layer was poor (Comparative Examples 4 to 5). In contrast, when the support adjacent to the optically anisotropic layer contained a specific surfactant, the alignment of the liquid crystal compound in the optically anisotropic layer was good and the occurrence of bright spot defects could be suppressed (Examples 1 to 16). In particular, a comparison of Examples 1 to 4 and 7 with Examples 5 and 6 indicates that when the specific surfactant had an ionic hydrophilic group (Examples 1 to 4 and 7), the alignment of the liquid crystal compound in the optically anisotropic layer was better and the occurrence of bright spot defects in the optical film was more suppressed. Furthermore, comparisons between Examples 1 and 10, and between Examples 2 and 7, have revealed that when the specific surfactant has an anionic hydrophilic group, the alignment of the liquid crystal compound in the optically anisotropic layer is further improved, and the occurrence of bright spot defects in the optical film can be further suppressed. Furthermore, comparisons between Examples 1 to 3 and 11 have revealed that when the specific surfactant is a polymer compound, the alignment of the liquid crystal compound in the optically anisotropic layer is further improved, and the occurrence of bright spot defects in the optical film can be further suppressed. Furthermore, comparisons between Examples 1 to 7 have revealed that when the hydrophobic group in the specific surfactant is an alkyl group having 12 to 18 carbon atoms, the occurrence of bright spot defects in the optical film can be further suppressed.

Claims

1. An optical film having a support (excluding those having an alignment layer) and an optically anisotropic layer adjacent to each other, the optically anisotropic layer is a layer formed using a composition for forming an optically anisotropic layer containing a polymerizable liquid crystal compound, the support contains a surfactant having a hydrophilic group and a hydrophobic group, at least a part of the surfactant is present in a region extending from the surface of the support on the optically anisotropic layer side to 10% of the thickness of the optically anisotropic layer, The optical film, wherein the hydrophobic group is at least one group selected from the group consisting of an alkyl group having 5 to 29 carbon atoms, a silicon-containing group, and a fluorine-containing group.

2. the optically anisotropic layer is a layer in which the alignment state of the polymerizable liquid crystal compound is fixed, The optical film according to claim 1 , wherein the orientation state is a homogeneous orientation or a twisted orientation.

3. The optical film according to claim 1 , wherein the support is a cellulose acylate film.

4. The optical film according to claim 1 , wherein the hydrophilic group of the surfactant is an ionic hydrophilic group.

5. The optical film according to claim 1 , wherein the hydrophilic group of the surfactant is an anionic hydrophilic group.

6. The optical film according to claim 1 , wherein the surfactant is a polymer compound.

7. 2. The optical film according to claim 1, wherein the hydrophobic group of the surfactant is an alkyl group having 12 to 18 carbon atoms.

8. A support preparation step of preparing the support according to claim 1; a rubbing step of subjecting the support to a rubbing treatment; an optically anisotropic layer forming step of forming an optically anisotropic layer on the support that has been subjected to the rubbing treatment, using a composition for forming an optically anisotropic layer that contains a polymerizable liquid crystal compound; The method for producing an optical film comprising the steps of:

9. The method for producing an optical film according to claim 8 , wherein the support preparation step comprises a step of casting a dope containing the surfactant according to claim 1 .

10. The method for producing an optical film according to claim 8 , wherein the support preparation step comprises a step of impregnating a surface of a polymer film with a composition containing the surfactant and the solvent according to claim 1 .

11. A polarizing plate comprising the optical film according to any one of claims 1 to 7 and a polarizer.

12. An image display device comprising the optical film according to any one of claims 1 to 7.

13. The image display device according to claim 12, which is a liquid crystal display device.

14. 13. The image display device according to claim 12, which is an organic electroluminescence display device.