Optical film, polarizing plate, and method for manufacturing optical film

Abstract

Provided are an optical film, a polarizing plate, and a method for manufacturing an optical film. Provided are an optical film in which a change in phase difference during a humidity reliability test is suppressed, a change in hue during a weather resistance test in the ultraviolet region is suppressed, and adhesiveness is excellent, and a polarizing plate including the optical film. An optical film composed of a resin having a birefringence in a prescribed range and having an orientation degree of 5% or more is used.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical film, a polarizing plate, and a manufacturing method of an optical film. BACKGROUND

[0002] In recent years, in the display market, there is a demand for extending the endurance time of a battery, and further, for reducing the display brightness to suppress heat generation. Therefore, as a polarizing plate for a display, a polarizing plate having a high light transmittance is sought. However, when such a polarizing plate having a high light transmittance is used for a display, there is a problem that the appearance deteriorates under a humidification condition.

[0003] Further, in recent years, displays are increasingly used in environments exposed to ultraviolet rays (for example, a PID (public information display), a mobile phone), and particularly for a polarizing plate in which an optical film is disposed on the panel side, there is a problem that the hue of the optical film changes due to ultraviolet light, and the quality of the display is impaired.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent No. 3325560 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present application has been made to solve the above-described conventional problems, and has an object to provide an optical film in which the phase difference change under a humidification condition is suppressed, the change in hue in a weather resistance test in the ultraviolet region is suppressed, and further, the adhesiveness is excellent, and a polarizing plate including the optical film.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The optical film in the embodiment of the present application is composed of a resin having a birefringence Δnxy of 0.015 or more, an orientation degree of 5% or more, an in-plane retardation Re(550) of 20 nm or less, a phase difference change rate of 10% or less after being kept at 65°C and 90% RH for 500 hours, and a change rate of b value of 1% or less in a weather resistance test in the ultraviolet region.

[0011] In one embodiment, the above-described resin includes a polycarbonate-based resin.

[0012] In one embodiment, the above-described polycarbonate-based resin includes a structural unit derived from a dihydroxy compound represented by the following formula (4).

[0013]

[0014] In one embodiment, the polycarbonate-based resin described above further contains a structural unit derived from an alicyclic dihydroxy compound represented by the following general formula (II), R 1 is a structure represented by the following (IIb), and n = 0.

[0015] HOCH2-R 1 -CH2OH (II)

[0016]

[0017] In one embodiment, the optical film described above has a thickness of 10 μm to 50 μm.

[0018] In another embodiment of the present application, a polarizing plate is provided. The polarizing plate includes a polarizing member, and the optical film described above adhered to at least one side of the polarizing member by means of an adhesive layer.

[0019] According to another aspect of the present application, a method for producing the optical film described above is provided. The production method includes a film forming step at a line speed of 7 m / min to 15 m / min.

[0020] Effects of the Invention

[0021] According to the embodiment of the present application, by forming a resin film composed of a specific resin and having a birefringence Δnxy of 0.015 or more under specific conditions, the degree of orientation reaches a certain value or more, and as a result, an optical film that suppresses changes in phase difference in a humidification reliability test, suppresses changes in color phase in a weather resistance test in the ultraviolet region, and further has excellent adhesiveness can be realized. DETAILED DESCRIPTION

[0022] Hereinafter, the embodiments of the present application will be described, but the present application is not limited to these embodiments.

[0023] (Definitions of Terms and Symbols)

[0024] The definitions of the terms and symbols in the present specification are shown below.

[0025] (1) Refractive Indexes (nx, ny, nz)

[0026] "nx" is the refractive index in the direction in which the refractive index in the plane reaches the maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction.

[0027] (2) In-Plane Phase Difference (Re)

[0028] "Re(A)" is an in-plane retardation measured at 23°C using light having a wavelength of A nm. For example, "Re(550)" is an in-plane retardation measured at 23°C using light having a wavelength of 550 nm. When the thickness of a layer (film) is set as d (nm), Re(A) is calculated by the equation Re(A) = (nx-ny) x d.

[0029] (3) Birefringence (Anxy)

[0030] The birefringence Anxy is calculated by the equation: Anxy = nx-ny.

[0031] A. Optical Film

[0032] The optical film of the embodiment of the present application is formed of a resin. As the resin, polycarbonate resin is typically exemplified. Therefore, the optical film of the embodiment of the present application is typically a polycarbonate resin film. Furthermore, the optical film of the embodiment of the present application is preferably free of an ultraviolet absorber. By the optical film being free of an ultraviolet absorber, it is possible to maintain a neutral color tone when applied to an image display device.

[0033] The birefringence Anxy of the resin constituting the above optical film is typically 0.015 or more, and preferably 0.018 or more. The upper limit of the birefringence Anxy of the above resin can be, for example, 0.040. By forming a resin film composed of a resin having such a birefringence Anxy at a linear velocity of a prescribed speed or more, the degree of orientation reaches a certain value or more, as a result of which it is possible to significantly suppress a change in retardation under a humidified condition.

[0034] The degree of orientation of the above optical film is 5% or more, preferably 5.5% or more, and more preferably 6% or more. The upper limit of the degree of orientation can be, for example, 70%. When the degree of orientation of the optical film is in this range, the adhesiveness of the optical film becomes good. The degree of orientation in this range can be achieved by forming the above resin film at a linear velocity in a prescribed range. The above degree of orientation is measured by, for example, X-ray diffraction method (XRD).

[0035] The in-plane retardation Re(550) of the above optical film is 20 nm or less, preferably 15 nm or less, and more preferably 10 nm or less. The lower limit can be, for example, 0 nm. That is, the above optical film is preferably substantially optically isotropic. Such an in-plane retardation Re(550) of the optical film can be obtained by forming the above resin film at a linear velocity in a prescribed range.

[0036] The change in retardation after the above optical film is stored under conditions of a temperature of 65°C and a humidity of 90% for 500 hours (humidification test) is preferably 10% or less, and more preferably 8% or less. The lower limit can be, for example, 0.01%. The above change in retardation (%) is calculated by the equation: Change in Retardation (%) = |(Re(550) after Humidification - Re(550) before Humidification) / Re(550) before Humidification) x 100|500 |Re0- Re1| / Re0 x 100 (%) is indicated. Re0 is the in-plane retardation (nm) of the optical film before the test, and Re1 is the in-plane retardation (nm) of the optical film after the test. 500 The phase difference change of the optical film is in this range, and in the case where the optical film is applied to an image display device, the following advantage is obtained: the color phase change caused by the phase difference at each place on the image display device becomes small, and color unevenness on the display can be suppressed.

[0037] The change in the b value of the above-described optical film is suppressed in the weather resistance test in the ultraviolet region. The change rate in the b value is 1% or less, and preferably 0.95% or less. The lower limit of the change rate in the b value is, for example, 0%. That is, the optical film can also be favorably used for applications requiring weather resistance. The optical film is able to obtain this advantage by containing a specific polycarbonate resin described later.

[0038] The thickness of the above-described optical film is preferably 10 μm to 50 μm, and more preferably 20 μm to 40 μm.

[0039] The moisture permeability of the above-described optical film is preferably 250 g / m 2 24 h or less, and more preferably 150 g / m 2 24 h or less. The lower limit can be, for example, 1 g / m 2 24 h. The moisture permeability of the optical film is in this range, and the advantage that the phase difference change under a humidified environment can be suppressed is obtained.

[0040] The absolute value of the photoelastic coefficient of the above-described optical film is preferably 2 x 10 -11 m 2 / N or less, and more preferably 2.0 x 10 -13 m 2 / N to 1.5 x 10 -11 m 2 / N, and further preferably 1.0 x 10 -12 m 2 / N to 1.2 x 10 -11 m 2 / N. The absolute value of the photoelastic coefficient is in this range, and the phase difference change does not easily occur in the case where a shrinkage stress is generated upon heating. As a result, in the case where the optical film is used for an image display device, thermal unevenness of the image display device can be favorably prevented.

[0041] According to the embodiment of the present application, as described above, by using a resin having a specific range of birefringence Δnxy, film formation is performed at a linear velocity within a prescribed range, whereby an optical film having a specific range of orientation degree can be obtained. The optical film satisfies a desired in-plane retardation (substantially optically isotropic), and further, both the suppression of phase difference variation in a humidity reliability test and the suppression of color phase variation in a weather resistance test in the ultraviolet region and good adhesiveness are taken into consideration.

[0042] By performing film formation of the above-described resin film at a linear velocity of not more than a prescribed velocity, an optical film substantially having optical isotropy can be obtained. However, when the linear velocity is not more than a prescribed velocity, the orientation degree of the obtained optical film decreases, which can result in phase difference variation in a humidity reliability test and a decrease in adhesiveness. Thus, by setting the above-described linear velocity to be more than a prescribed velocity, the orientation degree of the optical film increases, and phase difference variation in a humidity reliability test can be suppressed, and further, adhesiveness increases. That is, by optimizing the range of the above-described linear velocity, a desired in-plane retardation, the suppression of phase difference variation in a humidity reliability test, and excellent adhesiveness can be taken into consideration. Such an optical film is suitably used, for example, in a PID (public information display), a mobile phone.

[0043] B. Constituent material

[0044] The above-described optical film is typically a resin film containing a polycarbonate resin, as described above.

[0045] (Polycarbonate resin)

[0046] The polycarbonate resin of the present application contains at least a structural unit derived from a dihydroxy compound having a bonding structure represented by the following structural formula (1), which is produced by allowing a dihydroxy compound to react with a carbonate diester in the presence of a polymerization catalyst, the dihydroxy compound containing at least a dihydroxy compound having at least one bonding structure -CH2-O- in the molecule.

[0047]

[0048] Here, as the dihydroxy compound having the bonding structure represented by Structural Formula (1), any compound can be used as long as it is a compound having two alcoholic hydroxyl groups, contains a structure having a linking group -CH2-O- within the molecule, and is capable of reacting with a carbonic acid diester in the presence of a polymerization catalyst to produce a polycarbonate. A plurality of compounds can be used in combination. Furthermore, as the dihydroxy compound used in the polycarbonate resin of the present application, a dihydroxy compound not having the bonding structure represented by Structural Formula (1) can also be used in combination. Hereinafter, the dihydroxy compound having the bonding structure represented by Structural Formula (1) will be sometimes simply referred to as dihydroxy compound (A), and the dihydroxy compound not having the bonding structure represented by Structural Formula (1) will be sometimes simply referred to as dihydroxy compound (B).

[0049] (Dihydroxy compound (A))

[0050] The "linking group -CH2-O-" in the dihydroxy compound (A) refers to a structure in which atoms other than hydrogen atoms are mutually bonded to constitute a molecule. In this linking group, as an atom capable of bonding to an oxygen atom or an atom capable of simultaneously bonding to a carbon atom and an oxygen atom, a carbon atom is most preferable. The number of "linking group -CH2-O-" in the dihydroxy compound (A) is preferably 1 or more, and more preferably 2 to 4.

[0051] More specifically, as the dihydroxy compound (A), there can be mentioned, for example, a compound having an aromatic group in the side chain and an ether group bonded to the aromatic group in the main chain, such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isobutylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene; bis[4-(2-hydroxyethoxy)phenyl]methane, bis[4-(2-hydroxyethoxy)phenyl]diphenylmethane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]ethane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]-1-phenylethane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, 2,2-bis[4-(2-hydroxyethoxy)-3-methylphenyl]propane, 2,2-bis[3,5-dimethyl-4-(2-hydroxyethoxy)phenyl]propane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]-3,3,5-trimethylcyclohexane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,4-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,3-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 2,2-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]propane, 2,2-bis[(2-hydroxyethoxy)-3-isopropylphenyl]propane, 2,2-bis[3-tert-butyl-4-(2-hydroxyethoxy)phenyl]propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]butane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]-4-methylpentane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]octane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]decane, 2,2-bis[3-bromo-4-(2-hydroxyethoxy)phenyl]propane, 2,2-bis[3-cyclohexyl-4-(2-hydroxyethoxy)phenyl]propane; bis(hydroxyalkoxyaryl)cycloalkanes such as 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,1-bis[3-cyclohexyl-4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclopentane;4,4'-bis(2-hydroxyethoxy)phenyl sulfide, 4,4'-bis[4-(2-dihydroxyethoxy)-3-methylphenyl] sulfide, 4,4'-bis(2-hydroxyethoxyphenyl) sulfoxide, 4,4'-bis[4-(2-dihydroxyethoxy)-3-methylphenyl] sulfoxide, 4,4'-bis(2-hydroxyethoxyphenyl) sulfone, 4,4'-bis[4-(2-dihydroxyethoxy)-3-methylphenyl] sulfone, 1,4-bis(hydroxyethoxy)benzene, 1,3-bis(hydroxyethoxy)benzene, 1,2-bis(hydroxyethoxy)benzene, 1,3-bis[2-[4-(2-hydroxyethoxy)phenyl]propyl]benzene, 1,4-bis[2-[4-(2-hydroxyethoxy)phenyl]propyl]benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, 1,3-bis[4-(2-hydroxyethoxy)phenyl]-5,7-dimethyladamantane, a dihydroxy compound represented by the following formula (4) of an anhydrous sugar alcohol; and a compound having a cyclic ether structure such as a spiro glycol represented by the following general formula (6) can be used alone or in combination with two or more kinds.

[0052]

[0053] These dihydroxy compounds (A) can be used alone or in combination with two or more kinds. In the present application, as the dihydroxy compound represented by the aforementioned formula (4), isosorbide, isomannide, and isoidide in a stereoisomer relationship can be exemplified, and one kind can be used alone or two or more kinds can be used in combination.

[0054] Note that, among the dihydroxy compounds (A), isosorbide obtained by dehydration condensation of sorbitol manufactured from various starches which are abundant in resources and easily available, is most preferable in terms of easiness of acquisition and manufacture, optical properties, and moldability. In the present application, isosorbide is suitably used as the dihydroxy compound (A).

[0055] (Dihydroxy compound (B))

[0056] In this invention, dihydroxy compound (B) can be used as the dihydroxy compound, which is a dihydroxy compound other than dihydroxy compound (A). As dihydroxy compound (B), for example, alicyclic dihydroxy compounds, aliphatic dihydroxy compounds, oxoalkyl diols, aromatic dihydroxy compounds, and diols having cyclic ether structures can be used as dihydroxy compounds that form structural units of polycarbonate, and can be used together with dihydroxy compound (A) and, for example, dihydroxy compound shown in formula (4).

[0057] The alicyclic dihydroxy compound used in this invention is not particularly limited, but compounds typically containing a five-membered or six-membered ring structure are preferred. Furthermore, the six-membered ring structure can be fixed into a chair or boat shape by covalent bonds. By making the alicyclic dihydroxy compound a five- or six-membered ring structure, the heat resistance of the resulting polycarbonate can be improved. The alicyclic dihydroxy compound typically contains 70 or less carbon atoms, preferably 50 or less, and more preferably 30 or less. A higher number of carbon atoms results in higher heat resistance, but makes it difficult to synthesize or purify, or increases costs. A smaller number of carbon atoms makes it easier to purify and obtain.

[0058] As alicyclic dihydroxy compounds containing a five-membered ring structure or a six-membered ring structure that can be used in this invention, specifically, alicyclic dihydroxy compounds represented by the following general formula (II) or (III) can be listed.

[0059] HOCH2-R 1 -CH2OH (II)

[0060] HO-R 2 -OH (III)

[0061] In equations (II) and (III), R 1 R 2 These represent cycloalkylene groups with 4 to 20 carbon atoms, respectively.

[0062] Regarding cyclohexanediethanol, which is an alicyclic dihydroxy compound represented by the above general formula (II), including R in general formula (II) 1 Using the following general formula (IIa) (where R is...) 3 Various isomers (represented by alkyl groups or hydrogen atoms with 1 to 12 carbon atoms) are listed. Specific examples of such isomers include 1,2-cyclohexanediethanol, 1,3-cyclohexanediethanol, and 1,4-cyclohexanediethanol.

[0063]

[0064] Regarding tricyclodecanediethanol and pentacyclopentadecanedimethanol, which are alicyclic dihydroxy compounds represented by the above general formula (II), including R in general formula (II)1 various isomers represented by the following general formula (IIb) (in the formula, n represents 0 or 1).

[0065]

[0066] As the alicyclic dihydric compound represented by the above general formula (II), 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol, etc. are included. 1 various isomers represented by the following general formula (IIc) (in the formula, m represents 0 or 1). As such isomers, specifically, 2,6-decahydronaphthalene dimethanol, 1,5-decahydronaphthalene dimethanol, 2,3-decahydronaphthalene dimethanol, etc. can be exemplified.

[0067]

[0068] As the alicyclic dihydric compound represented by the above general formula (II), 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol, etc. are included. 1 various isomers represented by the following general formula (IId). As such isomers, specifically, 2,3-norbornanediol, 2,5-norbornanediol, etc. can be exemplified.

[0069]

[0070] As the alicyclic dihydric compound represented by the above general formula (II), 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol, etc. are included. 1 various isomers represented by the following general formula (IIe). As such isomers, specifically, 1,3-adamantanedimethanol, etc. can be exemplified.

[0071]

[0072] As the alicyclic dihydric compound represented by the above general formula (III), 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol, etc. are included. 2 various isomers represented by the following general formula (IIIa) (in the formula, R 3 represents an alkyl group having 1 to 12 carbon atoms or a hydrogen atom). As such isomers, specifically, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol, etc. can be exemplified.

[0073]

[0074] As the alicyclic dihydric compound represented by the above general formula (III), 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol, etc. are included. 2 various isomers represented by the following general formula (IIIb) (in the formula, n represents 0 or 1).

[0075]

[0076] As the alicyclic dihydric hydroxy compound represented by the above general formula (III), decalin diol or tricyclodecane diol, including R in general formula (III), can be used. 2 Various isomers represented by the following general formula (IIIc) (in the formula, m represents 0 or 1). As such isomers, specifically, 2,6-decalin diol, 1,5-decalin diol, 2,3-decalin diol, and the like can be used.

[0077]

[0078] As the alicyclic dihydric hydroxy compound represented by the above general formula (III), norbornane diol, including R in general formula (III), can be used. 2 Various isomers represented by the following general formula (IIId). As such isomers, specifically, 2,3-norbornane diol, 2,5-norbornane diol, and the like can be used.

[0079]

[0080] As the alicyclic dihydric hydroxy compound represented by the above general formula (III), adamantane diol, including R in general formula (III), can be used. 2 Various isomers represented by the following general formula (IIIe). As such isomers, specifically, 1,3-adamantane diol, and the like can be used.

[0081]

[0082] Among the specific examples of the above alicyclic dihydric hydroxy compound, particularly preferable are cyclohexane dimethanol, tricyclodecane dimethanol, adamantane diol, pentacyclopentadecane dimethanol, and from the viewpoints of easiness of acquisition and easiness of handling, 1,4-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, 1,2-cyclohexane dimethanol, tricyclodecane dimethanol are preferable. In the present application, as the dihydric hydroxy compound (B), tricyclodecane dimethanol is suitably used.

[0083] As the aliphatic dihydric hydroxy compound which can be used in the present application, for example, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexanediol can be exemplified. As the oxyalkylene glycol which can be used in the present application, for example, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol can be exemplified.

[0084] As the aromatic dihydroxy compound usable in the present application, for example, 2,2-bis(4-hydroxyphenyl)propane [= bisphenol A], 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxyphenyl)pentane, 2,4'-dihydroxy-diphenylmethane, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-5-nitrophenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 3,3-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, 4,4'-dihydroxy-2,5-diethoxydiphenyl ether, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 9,9-bis[4-(2-hydroxyethoxy-2-methyl)phenyl]fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-2-methylphenyl)fluorene can be exemplified.

[0085] As the diol having a cyclic ether structure usable in the present application, for example, spirodiols, dioxane diols can be exemplified. Note that the above exemplified compounds are examples of the alicyclic dihydroxy compound, the aliphatic dihydroxy compound, the oxyalkylene diol, the aromatic dihydroxy compound, the diol having a cyclic ether structure usable in the present application, but are not limited at all thereto. One or two or more of these compounds can be used together with the dihydroxy compound represented by formula (4).

[0086] By using these dihydroxy compounds (B), effects of improving the softness in accordance with the use, improving the heat resistance, improving the moldability, and the like can be obtained. The proportion of the dihydroxy compound (A), for example, the dihydroxy compound represented by formula (4), to the total dihydroxy compound constituting the polycarbonate resin of the present application is not particularly limited, and is preferably 10 mol% or more, more preferably 40 mol% or more, further preferably 60 mol% or more, and is preferably 90 mol% or less, more preferably 80 mol% or less, further preferably 70 mol% or less. If the proportion of the structural unit derived from the other dihydroxy compound is too much, the performance such as optical properties can sometimes be reduced.

[0087] Among the above other dihydroxy compounds, when an alicyclic dihydroxy compound is used, the proportion of the total of the dihydroxy compound (A), for example, the dihydroxy compound represented by formula (4), and the alicyclic dihydroxy compound, with respect to the total dihydroxy compound constituting the polycarbonate is not particularly limited, and is preferably 80 mol% or more, more preferably 90 mol% or more, and further preferably 95 mol% or more.

[0088] Further, regarding the proportion of the structural unit derived from the dihydroxy compound (A), for example, the dihydroxy compound represented by formula (4), and the structural unit derived from the alicyclic dihydroxy compound in the polycarbonate resin of the present application, these can be selected at an arbitrary ratio, and the proportion of the structural unit derived from the dihydroxy compound represented by formula (4) : the structural unit derived from the alicyclic dihydroxy compound = 1 : 99 to 99 : 1 (mol%) is preferred, and the proportion of the structural unit derived from the dihydroxy compound represented by formula (4) : the structural unit derived from the alicyclic dihydroxy compound = 10 : 90 to 90 : 10 (mol%) is particularly preferred. If the proportion of the structural unit derived from the dihydroxy compound represented by formula (4) is higher and the proportion of the structural unit derived from the alicyclic dihydroxy compound is lower than the above range, there is a tendency that coloring is easy, and conversely, if the proportion of the structural unit derived from the dihydroxy compound represented by formula (4) is lower and the proportion of the structural unit derived from the alicyclic dihydroxy compound is higher than the above range, there is a tendency that the molecular weight is difficult to increase.

[0089] Further, when an aliphatic dihydroxy compound, an oxyalkylene glycol, an aromatic dihydroxy compound, or a diol having a cyclic ether structure is used, the proportion of the total of the dihydroxy compound (A), for example, the dihydroxy compound represented by formula (4), and these various dihydroxy compounds, with respect to the total dihydroxy compound constituting the polycarbonate is not particularly limited, and can be selected at an arbitrary ratio. Further, the proportion of the structural unit derived from the dihydroxy compound (A), for example, the dihydroxy compound represented by formula (4), and the structural unit derived from these various dihydroxy compounds is also not particularly limited, and can be selected at an arbitrary ratio.

[0090] Details of the polycarbonate-based resin are described in, for example, Japanese Patent Application Publication No. 2012-31370 (Japanese Patent No. 5448264). The description of this patent document is incorporated herein by reference.

[0091] C. Method for manufacturing optical film

[0092] The optical film is obtained by film-forming a resin such as the polycarbonate-based resin described in item B. As the method of forming the film, any and appropriate molding process can be employed. As specific examples, there can be mentioned extrusion molding, blow molding, flow coating (e.g., flow casting), calender molding, and the like. Among them, extrusion molding or flow coating, which can improve the smoothness of the resulting film and can obtain good optical uniformity, can be preferably employed, and flow coating can be more preferably employed. The line speed of the flow coating is preferably 7 m / min to 15 m / min, and more preferably 7 m / min to 12 m / min. By film-forming the resin film described in item B at a line speed of not more than a prescribed speed, an optical film substantially having optical isotropy can be obtained. However, when the line speed is not more than a certain speed, the orientation degree of the resulting optical film decreases, which can lead to a change in the phase difference in the humidity reliability test and a decrease in the adhesiveness. Thus, by setting the line speed to be more than the certain speed, the orientation degree of the optical film increases, which can suppress a change in the phase difference in the humidity reliability test, and further, the adhesiveness improves. That is, by flow casting at a line speed within the above range, it is possible to balance the desired in-plane phase difference, suppression of a change in the phase difference in the humidity reliability test, and excellent adhesiveness. Further, by flow casting at a line speed within the above range, it is possible to suppress the film thickness unevenness in the MD direction (lengthwise direction) and the phase difference unevenness caused by the film thickness unevenness.

[0093] D. Polarizing plate

[0094] The polarizing plate typically has a polarizing member and the above optical film attached to at least one surface of the polarizing member with an adhesive layer. As described above, the adhesiveness of the optical film to the polarizing member is excellent. In the polarizing member, a protective layer can be provided on at least one surface of the polarizing member. Further, an adhesive layer and a spacer can be provided on the surface of the polarizing plate opposite to the viewing side. As to the polarizing member, the protective layer, the adhesive layer, and the spacer, the constitution known in the art can be employed, and thus detailed description is omitted.

[0095] As the adhesive composition constituting the above adhesive layer, an active energy ray-curable adhesive composition is typically exemplified. The active energy ray-curable adhesive composition contains an active energy ray-curable compound.

[0096] The active energy ray-curable adhesive composition of the present application is, for example, an active energy ray-curable adhesive composition containing active energy ray-curable compounds (A), (B), and (C) as curable components, and contains, when the total amount of the composition is set to 100% by weight, 29.0 (MJ / m 3 )1 / 2or more and 32.0 (MJ / m 3(A) 0.0–4.0% by weight of active energy ray-cured compound (A) with an SP value of 18.0 (MJ / m²) 3 More than 1 / 2 but less than 21.0 (MJ / m³) 3 The active energy ray-cured compound (B) was 5.0–98.0% by weight, with an SP value of 21.0 (MJ / m²). 3 ) more than 1 / 2 and 26.0 (MJ / m 3 The active energy ray-curable compound (C) is less than 1 / 2 in weight, and the content is 5.0 to 98.0% by weight. It should be noted that in this invention, "total composition" refers to the total amount of various initiators and / or additives included in addition to the active energy ray-curable compound.

[0097] The active energy radiation-curable compound (A) only needs to have free radical polymerizable groups such as (meth)acrylate groups and an SP value of 29.0 (MJ / m²). 3 ) more than 1 / 2 and 32.0 (MJ / m 3 Compounds with a content of 1 / 2 or less can be used without limitation. Specific examples of active energy ray-curable compounds (A) include hydroxyethyl acrylamide (SP value 29.5) and N-hydroxymethyl acrylamide (SP value 31.5). It should be noted that in this invention, (meth)acrylate groups refer to acrylate groups and / or methacrylate groups.

[0098] Active energy radiation-cured compound (B) only needs to have free radical polymerizable groups such as (meth)acrylate groups and an SP value of 18.0 (MJ / m²). 3 More than 1 / 2 but less than 21.0 (MJ / m³) 3)1 / 2or more and 26.0 (MJ / m2)1 / 2or less can be used without limitation. As specific examples of the active energy ray-curable compound (B), for example, tripropyleneglycol diacrylate (SP value 19.0), 1,9-nonanediol diacrylate (SP value 19.2), tricyclodecanedimethanol diacrylate (SP value 20.3), cyclic trimethylolpropane formal acrylate (SP value 19.1), dioxanediol diacrylate (SP value 19.4), EO-modified diglycerol tetraacrylate (SP value 20.9), and the like can be listed. Note that, as the active energy ray-curable compound (B), commercially available products can also be appropriately used, for example, ARONIX M-220 (manufactured by Toagosei Co., Ltd., SP value 19.0), Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 19.2), Light Acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 20.9), Light Acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 20.3), SR-531 (manufactured by SARTOMER Co., Ltd., SP value 19.1), CD-536 (manufactured by SARTOMER Co., Ltd., SP value 19.4), and the like can be listed.

[0099] The active energy ray-curable compound (C) is a compound having a (meth)acrylate group or the like as a radical polymerizable group, and having an SP value of 21.0 (MJ / m2)1 / 2or more and 26.0 (MJ / m2)1 / 2or less. As specific examples of the active energy ray-curable compound (C), for example, acryloyl morpholine (SP value 22.9), N-methoxymethyl acrylamide (SP value 22.9), N-ethoxymethyl acrylamide (SP value 22.3), and the like can be listed. Note that, as the active energy ray-curable compound (C), commercially available products can also be appropriately used, for example, ACMO (manufactured by KOHJIN Co., Ltd., SP value 22.9), Wasmer 2MA (manufactured by KASAI KOSAN Co., Ltd., SP value 22.9), Wasmer EMA (manufactured by KASAI KOSAN Co., Ltd., SP value 22.3), Wasmer 3MA (manufactured by KASAI KOSAN Co., Ltd., SP value 22.4), and the like can be listed. 3 )1 / 2or more and 26.0 (MJ / m2)1 / 2or less can be used without limitation. As specific examples of the active energy ray-curable compound (B), for example, tripropyleneglycol diacrylate (SP value 19.0), 1,9-nonanediol diacrylate (SP value 19.2), tricyclodecanedimethanol diacrylate (SP value 20.3), cyclic trimethylolpropane formal acrylate (SP value 19.1), dioxanediol diacrylate (SP value 19.4), EO-modified diglycerol tetraacrylate (SP value 20.9), and the like can be listed. Note that, as the active energy ray-curable compound (B), commercially available products can also be appropriately used, for example, ARONIX M-220 (manufactured by Toagosei Co., Ltd., SP value 19.0), Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 19.2), Light Acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 20.9), Light Acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 20.3), SR-531 (manufactured by SARTOMER Co., Ltd., SP value 19.1), CD-536 (manufactured by SARTOMER Co., Ltd., SP value 19.4), and the like can be listed. 3 )1 / 2or more and 26.0 (MJ / m2)1 / 2or less can be used without limitation. As specific examples of the active energy ray-curable compound (B), for example, tripropyleneglycol diacrylate (SP value 19.0), 1,9-nonanediol diacrylate (SP value 19.2), tricyclodecanedimethanol diacrylate (SP value 20.3), cyclic trimethylolpropane formal acrylate (SP value 19.1), dioxanediol diacrylate (SP value 19.4), EO-modified diglycerol tetraacrylate (SP value 20.9), and the like can be listed. Note that, as the active energy ray-curable compound (B), commercially available products can also be appropriately used, for example, ARONIX M-220 (manufactured by Toagosei Co., Ltd., SP value 19.0), Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 19.2), Light Acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 20.9), Light Acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd., SP value 20.3), SR-531 (manufactured by SARTOMER Co., Ltd., SP value 19.1), CD-536 (manufactured by SARTOMER Co., Ltd., SP value 19.4), and the like can be listed.

[0100] Details of the above-described adhesive composition are described, for example, in Japanese Patent Application Publication No. 2019-147865. The description of this publication is incorporated herein by reference. By adhering the above-described optical film to the adhesive layer composed of the above-described adhesive composition, the adhesion of the optical film becomes more excellent.

[0101] Examples

[0102] Hereinafter, the present application will be specifically described by way of examples, but the present application is not limited to these examples. Note that the measuring method and evaluation method of each property are shown below.

[0103] (1) In-plane retardation

[0104] The optical film obtained in the examples and comparative examples was cut into 4 cm in length and 4 cm in width as a measurement sample. With respect to the measurement sample, the in-plane retardation Re(550) was measured using an article manufactured by Axometrics, Inc. under the product name "Axoscan".

[0105] (2) Refractive index and birefringence Δnxy

[0106] Measured with an Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.). The measurement was performed in an environment at 23°C.

[0107] (3) Thickness

[0108] The thickness of 10 μm or less was measured using an interference film thickness meter (product name "MCPD-9800", manufactured by Otsuka Electronics Co., Ltd.). The thickness of more than 10 μm was measured using a digital micrometer (product name "KC-351C", manufactured by ANRITSU Co., Ltd.).

[0109] (4) Orientation degree

[0110] The orientation degree was calculated by X-ray diffraction (XRD) using the optical film obtained in the examples and comparative examples.

[0111] (5) Change in humidification retardation

[0112] The optical film obtained in the examples and comparative examples was cut into 5 cm x 5 cm, and an adhesive was attached to one side using a hand roller to obtain a test piece by attaching the adhesive side to one side of alkali glass. The test piece was stored in an oven at a temperature of 65°C and a humidity of 90% for 500 hours (humidification test), and the change in retardation (%) before and after the test was calculated. The case where the change in retardation was 10% or less was evaluated as good, and the case where the change in retardation exceeded 10% was evaluated as poor.

[0113] (6) Parallel color a value and b value

[0114] The parallel color a value and the parallel color b value of the optical film obtained in the examples and the comparative examples were found. The measurement was performed using a spectrophotometer (manufactured by Shimadzu Corporation, trade name "V-7100"). The case where the change rate of the b value before being put into the ultraviolet fading tester (device name; ultraviolet fading meter tester U48, manufactured by Suga Test Instruments Co., Ltd.) and the b value after being put in for 100 h was 1% or less was recorded as good, and the case where the change rate exceeded 1% was recorded as poor.

[0115] (7) Adhesiveness

[0116] The optical film obtained in the examples and the comparative examples was bonded to a polarizing member to obtain a laminate. The obtained laminate was cut to have a size of 200 mm in a direction parallel to the stretching direction of the polarizing member and 15 mm in a direction orthogonal thereto, and the laminate was attached to a glass plate. Furthermore, a notch was made between the optical film and the polarizing member with a cutter, and the optical film and the polarizing member were peeled at a peeling speed of 1000 mm / min in a 90-degree direction using a TENSILON universal testing machine (manufactured by A&D Company Limited), and the peeling strength (N / 15 mm) was measured. The case where the peeling strength was 1 N / 15 mm or more was recorded as good, and the case where the peeling strength was less than 1 N / 15 mm was recorded as poor.

[0117] [Example 1]

[0118] In a reaction vessel, 47.19 parts by mass of tricyclodecane dimethanol (hereinafter sometimes abbreviated as "TCDDM"), 175.1 parts by mass of diphenyl carbonate (hereinafter sometimes abbreviated as "DPC"), and 0.979 parts by mass of a 0.2 mass% aqueous cesium carbonate solution as a catalyst were charged with respect to 81.98 parts by mass of isosorbide (hereinafter sometimes abbreviated as "ISB"), and a heating bath temperature was raised to 150°C under a nitrogen atmosphere, and the raw materials were dissolved with stirring as needed (about 15 minutes) as a procedure of the first stage of the reaction. Next, the pressure was set to 13.3 kPa from the normal pressure, and the heating bath temperature was raised to 190°C over 1 hour, and the generated phenol was taken out to the outside of the reaction vessel. After the entire reaction vessel was maintained at 190°C for 15 minutes, the pressure in the reaction vessel was set to 6.67 kPa, and the heating bath temperature was raised to 230°C over 15 minutes, and the generated phenol was taken out to the outside of the reaction vessel as a procedure of the second stage. Since the stirring torque of the stirrer gradually increased, the temperature was raised to 250°C over 8 minutes, and further, the pressure in the reaction vessel was reduced to 0.200 kPa or less in order to remove the generated phenol. After the prescribed stirring torque was reached, the reaction was ended, and the generated reaction product was extruded into water, and a pellet of polycarbonate resin was obtained. The birefringence Δnxy of the obtained polycarbonate resin was 0.015. After the obtained polycarbonate resin was vacuum-dried at 100°C for 12 hours, an optical film composed of polycarbonate resin was produced using a film production device provided with a single-screw extruder (Toshiba Machine Co., Ltd., barrel set temperature: 250°C), a T die (width: 1700 mm, set temperature: 250°C), a casting roll (set temperature: 60°C), and a winder, at a film production line speed of 7 m / min. The orientation degree of the obtained optical film was 7.4%, the in-plane retardation Re(550) was 6 nm, and the thickness was 40 μm. The obtained optical film was subjected to the evaluations of (5) to (7) described above. The results are shown in Table 1.

[0119] [Example 2]

[0120] An optical film was obtained by the same operation as in Example 1, except that the film production line speed was set to 8 m / min and the thickness was set to 30 μm. The orientation degree of the obtained optical film was 5.7%, and the in-plane retardation Re(550) was 3 nm. The obtained optical film was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0121] [Example 3]

[0122] An optical film was obtained in the same manner as in Example 1, except that the birefringence Δnxy of the polycarbonate resin was set to 0.018, the film- forming line speed was set to 10 m / min, and the thickness was set to 20 μm. The degree of orientation of the obtained optical film was 6.1%, and the in-plane retardation Re(550) was 2 nm. The obtained optical film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0123] [Example 4]

[0124] An optical film was obtained in the same manner as in Example 1, except that the birefringence Δnxy of the polycarbonate resin was set to 0.024, the film- forming line speed was set to 12 m / min, and the thickness was set to 20 μm. The degree of orientation of the obtained optical film was 8.1%, and the in-plane retardation Re(550) was 2 nm. The obtained optical film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0125] [Comparative Example 1]

[0126] An optical film was obtained in the same manner as in Example 1, except that the birefringence Δnxy of the polycarbonate resin was set to 0.016, and the film- forming line speed was set to 5 m / min. The degree of orientation of the obtained optical film was 4.8%, and the in-plane retardation Re(550) was 5 nm. The obtained optical film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0127] [Comparative Example 2]

[0128] An optical film was obtained in the same manner as in Example 1, except that a triacetate cellulose (TAC) film (Konica Minolta Optica, Inc., product name "KC4UA") having a birefringence Δnxy of 0.018 was used, and the line speed was set to 15 m / min. The degree of orientation of the obtained optical film was 5.1%, and the in-plane retardation Re(550) was 2 nm. The obtained optical film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0129] [Comparative Example 3]

[0130] (Polymerization of the polyester carbonate resin)

[0131] Polymerization was performed using a batch polymerization apparatus composed of 2 vertical reactors equipped with stirring blades and reflux coolers controlled at 100°C. Bis[9-(2-phenoxy carbonyl ethyl) fluorene-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiro glycol (SPG) 42.28 parts by mass (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by mass (0.298 mol), and calcium acetate monohydrate 1.19 x 10 -2 -4 parts by mass (6.78 x 10 -5 -4 mol) as a catalyst were charged. After the inside of the reactor was replaced with nitrogen gas under reduced pressure, the reactor was warmed with a heating medium, and stirring was started when the inside temperature reached 100°C. The inside temperature reached 220°C 40 minutes after the start of warming, and the temperature was controlled so as to maintain this temperature, and at the same time, the pressure was reduced. Phenol vapor produced along with the polymerization reaction was introduced into a reflux cooler controlled at 100°C, and a certain amount of monomer components contained in the phenol vapor was returned to the reactor, and the uncondensed phenol vapor was introduced into a condenser controlled at 45°C and recovered. Nitrogen gas was introduced into the first reactor, and after the pressure was temporarily returned to the atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Subsequently, the temperature increase and pressure reduction in the second reactor were started, and the inside temperature was controlled to 240°C and the pressure was controlled to 0.2 kPa in 50 minutes. Then, the polymerization was performed until a predetermined stirring power was reached. Nitrogen gas was introduced into the reactor to return the pressure when the predetermined power was reached, and the polyester carbonate resin produced was extruded into water, and the strands were cut to obtain pellets. The birefringence Δnxy of the obtained polycarbonate resin was 0.012.

[0132] (Optical film production)

[0133] After the obtained polyester carbonate resin (pellets) were vacuum-dried at 80°C for 5 hours, an optical film having a length of 40 μm was produced using a film production apparatus equipped with a single-screw extruder (Toshiba Machine Co., Ltd., barrel set temperature: 270°C), a T die (width: 1700 mm, set temperature: 270°C), a casting roll (set temperature: 75°C), and a winder, at a film production line speed of 8 m / min. The obtained optical film had an orientation degree of 4.3% and an in-plane retardation Re(550) of 7 nm. The obtained optical film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0134] [Comparative Example 4]

[0135] A cellulose triacetate film having a thickness of 40 μm was subjected to a brushing treatment, and was subjected to coating. The optical film obtained had an in-plane retardation Re(550) of 3 nm and a thickness of 2 μm. The optical film obtained was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0136] [Table 1]

[0137]

[0138] As is apparent from Table 1, the optical films of the Examples of the present application are excellent in each of the change in the retardation in the presence of moisture, the weather resistance, and the adhesion. It is presumed that this is achieved by film formation of a resin film containing a specific polycarbonate resin having a specific birefringence Δnxy at a specific line speed. Furthermore, as is apparent from the comparison between Examples 1 to 4 and Comparative Example 4, by using an optical film containing no ultraviolet absorber, the change in the color phase in the weather resistance test can be suppressed.

[0139] Industrial Applicability

[0140] The optical film and the polarizing plate of the embodiments of the present application are suitably used for image display devices.

Claims

1. A method for producing an optical film, comprising a film forming step at a line speed of 7 m / min to 15 m / min, The optical film is an optical film composed of a resin having a birefringence Δnxy of 0.015 or more, an orientation degree of 5% or more, an in-plane retardation Re(550) of 20 nm or less, a change rate of the retardation after 500 hours at 65°C and 90% RH of 10% or less, and a change rate of the b value in the ultraviolet region weather resistance test of 1% or less, wherein Re(550) is an in-plane retardation measured at 23°C using light of wavelength 550 nm, the resin comprises a polycarbonate resin, the polycarbonate resin comprises structural units derived from a dihydroxy compound represented by the following formula (4) and structural units derived from an alicyclic dihydroxy compound, The alicyclic dihydroxy compound is represented by the following general formula (II), R 1 is a structure represented by the following (IIb), n = 0, HOCH2-R 1 -CH2OH (II) 。 2. The method for producing according to claim 1, wherein the optical film has a thickness of 10 μm to 50 μm.

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