WO2020184220A1

WO2020184220A1 - Retarder film and polarizer plate having retarder layer

Info

Publication number: WO2020184220A1
Application number: PCT/JP2020/008311
Authority: WO
Inventors: 歩夢中原; 清水　享
Original assignee: 日東電工株式会社
Priority date: 2019-03-12
Filing date: 2020-02-28
Publication date: 2020-09-17
Also published as: JP7322135B2; KR20210136993A; JP2023129640A; TW202039658A; CN113557458A; JPWO2020184220A1

Abstract

Provided is a retarder film in which whitening and cracking are suppressed and that has superior folding endurance. In the present invention, a film containing a prescribed polycarbonate-based resin, having Re(450)/Re(550) of 0.98-1.03 and having Re(550) of 200-400 nm, is used.

Description

Differential film and polarizing plate with retardation layer

The present invention relates to a retardation film and a polarizing plate with a retardation layer.

In recent years, with the spread of thin displays, an image display device (organic EL display device) equipped with an organic EL panel has been proposed. The organic EL panel has a highly reflective metal layer, and tends to cause problems such as reflection of external light and reflection of the background. Therefore, it is known that these problems can be prevented by providing a retardation film. However, when a conventional retardation film is used in an image display device, whitening and / or cracks may occur with use, and the folding resistance may be insufficient.

Japanese Patent No. 3325560

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is a retardation film in which whitening and cracks are suppressed and has excellent folding resistance, and such a retardation film. It is an object of the present invention to provide a polarizing plate with a retardation layer including a film.

The retardation film in the embodiment of the present invention contains a polycarbonate-based resin, and Re (450) / Re (550) is 0.98 to 1.03, and Re (550) is 200 nm to 400 nm.
In one embodiment, the polycarbonate resin contains a structural unit derived from a dihydroxy compound represented by the following formula (4).

In one embodiment, the polycarbonate resin further comprises a structural unit derived from the alicyclic dihydroxy compound, the alicyclic dihydroxy compound is represented by the following general formula (II), and R ¹ is the following ( It is a structure represented by IIb), and n = 0.

HOCH _2- R ^1- CH ₂ OH (II)

In one embodiment, the retardation film suppresses cracks in the deformability test.
In one embodiment, the retardation film suppresses whitening and cracking in the sebum resistance test.
In one embodiment, the retardation film has a MIT count of 500 or more.
In one embodiment, the moisture permeability of the retardation film is less than 100g ^/ m 2 · 24h.
In one embodiment, the retardation change of the retardation film after storage for 500 hours under the conditions of a temperature of 65 ° C. and a humidity of 90% is 1.0% or less.
According to another aspect of the present invention, a polarizing plate with a retardation layer is provided. The polarizing plate with a retardation layer includes a retardation layer and a polarizer, and the retardation layer is composed of the retardation film.
According to one embodiment, the polarizing plate with a retardation layer is used on the visual side of an image display device.

According to the embodiment of the present invention, a resin film containing a predetermined polycarbonate-based resin, having a Re (450) / Re (550) of 0.98 to 1.03 and an in-plane retardation of 200 nm to 400 nm. By using it, it is possible to realize a retardation film in which whitening and cracks are suppressed and excellent in folding resistance.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols herein are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), and “ny” is the in-plane direction orthogonal to the slow-phase axis (that is, the phase-advance axis direction). Is the refractive index of, and "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
“Re (λ)” is an in-plane phase difference measured with light having a wavelength of λ nm at 23 ° C. For example, "Re (550)" is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained by the formula: Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in the thickness direction (Rth)
“Rth (λ)” is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (550)" is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is obtained by the formula: Rth (λ) = (nx−nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.

A. Phase difference film The retardation film according to the embodiment of the present invention contains a polycarbonate resin. The retardation film according to the embodiment of the present invention is typically a stretched film of a polycarbonate resin film.

The retardation film exhibits a flat wavelength dispersion characteristic in which the retardation value hardly changes depending on the wavelength of the measurement light. The Re (450) / Re (550) of the retardation film is 0.98 to 1.03, preferably 0.99 to 1.03, and more preferably 1.00 to 1.03. By using a polycarbonate resin capable of obtaining such Re (450) / Re (550), a retardation film in which whitening and cracks are suppressed in a sebum resistance test and is excellent in shape processability and folding resistance can be obtained. Can be obtained. Further, with such a wavelength dispersion characteristic, excellent antireflection characteristics can be realized in a wide band.

The retardation characteristic of the retardation film is preferably nx> ny ≧ nz. The in-plane retardation Re (550) of the retardation layer film is 200 nm to 400 nm, preferably 220 nm to 350 nm, and more preferably 250 nm to 300 nm. That is, the retardation film can function as a λ / 2 plate. Here, "ny = nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny <nz may be satisfied as long as the effect of the present invention is not impaired.

The retardation film preferably has an Nz coefficient of 0.9 to 1.5, and more preferably 0.9 to 1.3. When the Nz coefficient is in such a range, an image display device having excellent dependence on the viewing angle of the reflectance and the reflected hue can be obtained.

The moisture permeability of the retardation film is preferably not more than 100g ^/ m 2 · 24h, more preferably not more than 90g ^/ m 2 · 24h. The lower limit may be, for example, 1g ^/ m 2 · 24h. If the moisture permeability of the retardation film is in such a range, it is possible to obtain an advantage that the change in retardation can be suppressed in a humidified environment.

The retardation change of the retardation film after storage (humidification test) for 500 hours under the conditions of a temperature of 65 ° C. and a humidity of 90% is preferably 1.0% or less, more preferably 0.9% or less. Is. The lower limit can be, for example, 0.01%. The phase difference change (%) is represented by | (Re _500- Re ₀ ) / Re ₀ | × 100 (%). Re ₀ is the in-plane retardation (nm) of the retardation film before the start of the test, and Re ₅₀₀ is the in-plane retardation (nm) of the retardation film after the test. If the phase difference change of the retardation film is within such a range, it is possible to obtain an advantage that the hue change due to the phase difference at each location on the image display device is small and the occurrence of color unevenness on the display is suppressed. ..

The thickness of the retardation film can be appropriately set so as to function as a λ / 2 plate. The thickness is preferably 20 μm to 80 μm, more preferably 30 μm to 60 μm, and even more preferably 35 μm to 50 μm.

In the above retardation film, the absolute value of the photoelastic coefficient is preferably 2 × 10 ^-11 m ² / N or less, more preferably 2.0 × 10 ^-13 m ² / N to 1.5 × 10 ^-11 m ^2. / N, more preferably from ^{^{^{1.0 × 10 -12 m 2 /N~1.2×10 -11}}} m 2 / N. When the absolute value of the photoelastic coefficient is in such a range, a phase difference change is unlikely to occur when a shrinkage stress during heating occurs. As a result, thermal unevenness of the obtained image display device can be satisfactorily prevented.

The above retardation film has cracks suppressed in the deformability test. That is, the retardation film can be satisfactorily used even in applications requiring irregular shapes. Such an advantage can be obtained by including the specific polycarbonate resin described later in the retardation film.

The above retardation film has suppressed whitening and cracks in the sebum resistance test. That is, even when the retardation film is used, for example, on the visual side of an image display device and is continuously in contact with the user, it can retain good characteristics. This solves the problem recognized only after the retardation film is used on the visual side of the image display device for a long period of time, which is an unexpectedly excellent effect. Such an advantage can be obtained by including the specific polycarbonate resin described later in the retardation film.

The retardation film has a MIT number of 500 times or more. That is, the retardation film can exhibit excellent fold resistance even when used in a bendable (preferably foldable) image display device. Such an advantage can be obtained by stretching a resin film containing a specific polycarbonate resin described later under a specific stretching method and stretching conditions described later to form a retardation film.

B. As described above, the resin film retardation film is typically a stretched film of a polycarbonate resin film.

(Polycarbonate resin)
The polycarbonate resin according to the present invention contains at least a structural unit derived from a dihydroxy compound having a bonding structure represented by the following structural formula (1), and has at least one bonding structure-CH _2- O- in the molecule. It is produced by reacting a dihydroxy compound containing at least the dihydroxy compound having the above with a carbonic acid diester in the presence of a polymerization catalyst.

Here, the dihydroxy compound having a bonding structure represented by the structural formula (1) includes a structure having _two alcoholic hydroxyl groups and having a linking group −CH2-O— in the molecule, and is a polymerization catalyst. Any compound having any structure can be used as long as it is a compound capable of reacting with a carbonic acid diester to form polycarbonate in the presence of the compound, and a plurality of types may be used in combination. Further, as the dihydroxy compound used for the polycarbonate resin according to the present invention, a dihydroxy compound having no binding structure represented by the structural formula (1) may be used in combination. Hereinafter, the dihydroxy compound having a binding structure represented by the structural formula (1) is abbreviated as the dihydroxy compound (A), and the dihydroxy compound having no binding structure represented by the structural formula (1) is abbreviated as the dihydroxy compound (B). Sometimes.

(Dihydroxy compound (A))
The "linking group -CH 2 _-O-" in the dihydroxy compounds (A), is meant the structure that constitutes the molecule bonded to each other with atoms other than hydrogen atoms. In this linking group, at least an atom to which an oxygen atom can be bonded or an atom to which a carbon atom and an oxygen atom can be bonded at the same time is most preferably a carbon atom. The number of "linking groups _-CH 2 -O-" in the dihydroxy compound (A) is preferably 1 or more, more preferably 2 to 4.

More specifically, examples of the dihydroxy compound (A) include 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene and 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-) As exemplified by (2-hydroxyethoxy) -3-tert-butyl-6-methylphenyl) fluorene, 9,9-bis (4- (3-hydroxy-2,2-dimethylpropoxy) phenyl) fluorene, Compounds having an aromatic group on the side chain and an ether group bonded to the aromatic group on the main chain, 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) ethoxy ) -3-Phenylphenyl] propane, 2,2-bis [(2-hydroxyethoxy) -3-isopropylphenyl] propane, 2,2-bis [3-tert-butyl-4- (2-hydroxyethoxy) phenyl ] Lopan, 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, Bis (hydroxyalkoxyaryl) alkanes, as exemplified by 2,2-bis [3-cyclohexyl-4- (2-hydroxyethoxy) phenyl] propane, 1,1-bis [4- (2-hydroxyethoxy) ethoxy] ) Phenyl] cyclohexane, 1,1-bis [3-cyclohexyl-4- (2-hydroxyethoxy) phenyl] cyclohexane, 1,1-bis [4- (2-hydroxyethoxy) phenyl] cyclopentane as exemplified , Bis (hydroxyalkoxyaryl) cycloalkans, 4,4'-bis (2-hydroxyethoxy) diphenyl ether, 4,4'-bis (2-hydroxyethoxy) -3,3'-dimethyldiphenyle Dihydroxyalkoxydiaryl ethers, 4,4'-bis (2-hydrochiethoxyphenyl) sulfide, 4,4'-bis [4- (2-dihydroxyethoxy) -3-methylphenyl, as exemplified by tel. ] Bishydroxyalkoxyaryl sulfides, 4,4'-bis (2-hydrochiethoxyphenyl) sulfoxides, 4,4'-bis [4- (2-dihydroxyethoxy) -3-methyl, as exemplified by sulfides. Bishydroxyalkoxyaryl sulfoxides, 4,4'-bis (2-hydrochiethoxyphenyl) sulfides, 4,4'-bis [4- (2-dihydroxyethoxy) -3-, as exemplified by phenyl] sulfoxides. Methylphenyl] sulfides, such as bishydroxyalkoxyarylsulfones, 1,4-bishydroxyethoxybenzene, 1,3-bishydroxyethoxybenzene, 1,2-bishydroxyethoxybenzene, 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] Examples thereof include compounds having a cyclic ether structure such as -5,7-dimethyladamantane, anhydrous sugar alcohol represented by the dihydroxy compound represented by the following formula (4), and spiroglycol represented by the following general formula (6). These may be used alone or in combination of two or more.

These dihydroxy compounds (A) may be used alone or in combination of two or more. In the present invention, examples of the dihydroxy compound represented by the above formula (4) include isosorbide, isomannide, and isoidet having a stereoisomeric relationship, and one of these may be used alone or two or more. May be used in combination.

Among the dihydroxy compounds (A), isosorbide obtained by dehydration condensation of sorbitol, which is abundant as a resource and is produced from various easily available starches, is easy to obtain and produce, and has optical properties. Most preferable from the viewpoint of moldability. In the present invention, isosorbide is preferably used as the dihydroxy compound (A).

(Dihydroxy compound (B))
In the present invention, the dihydroxy compound (B), which is a dihydroxy compound other than the dihydroxy compound (A), may be used as the dihydroxy compound. As the dihydroxy compound (B), for example, an alicyclic dihydroxy compound, an aliphatic dihydroxy compound, an oxyalkylene glycol, an aromatic dihydroxy compound, and diols having a cyclic ether structure are used as the dihydroxy compound as a constituent unit of the polycarbonate. It can be used together with the dihydroxy compound (A), for example, the dihydroxy compound represented by the formula (4).

The alicyclic dihydroxy compound that can be used in the present invention is not particularly limited, but a compound having a 5-membered ring structure or a 6-membered ring structure is usually used. Further, the 6-membered ring structure may be fixed in a chair shape or a boat shape by a covalent bond. Since the alicyclic dihydroxy compound has a 5-membered ring or 6-membered ring structure, the heat resistance of the obtained polycarbonate can be increased. The number of carbon atoms contained in the alicyclic dihydroxy compound is usually 70 or less, preferably 50 or less, and more preferably 30 or less. The larger this value, the higher the heat resistance, but the synthesis becomes difficult, the purification becomes difficult, and the cost becomes high. The smaller the number of carbon atoms, the easier it is to purify and obtain.

Specific examples of the alicyclic dihydroxy compound containing a 5-membered ring structure or a 6-membered ring structure that can be used in the present invention include alicyclic dihydroxy compounds represented by the following general formulas (II) or (III). Be done.
HOCH _2- R ^1- CH ₂ OH (II)
HO-R ^2- OH (III)
(In formulas (II) and (III), R ¹ and R ² each represent a cycloalkylene group having 4 to 20 carbon atoms.)
As the cyclohexanedimethanol which is an alicyclic dihydroxy compound represented by the general formula (II), in the general formula (II), R ¹ is the following general formula (IIa) (in the formula, R ³ has 1 to 1 carbon atoms). Includes various isomers represented by 12 alkyl groups or hydrogen atoms). Specific examples of such are 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and the like.

As tricyclodecanedimethanol and pentacyclopentadecanedimethanol, which are alicyclic dihydroxy compounds represented by the above general formula (II), in the general formula (II), R ¹ is the following general formula (IIb) (in the formula). , N represents 0 or 1) and includes various isomers represented by).

As the decalin dimethanol or tricyclotetradecane dimethanol which is an alicyclic dihydroxy compound represented by the general formula (II), in the general formula (II), R ¹ is the following general formula (IIc) (in the formula, in the formula). m includes various isomers represented by 0 or 1). Specific examples thereof include 2,6-decalin dimethanol, 1,5-decalin dimethanol, and 2,3-decalin dimethanol.

Further, as norbornane dimethanol which is an alicyclic dihydroxy compound represented by the above general formula (II), various isomers in which R ¹ is represented by the following general formula (IId) in the general formula (II) are used. Include. Specific examples of such a substance include 2,3-norbornane dimethanol, 2,5-norbornane dimethanol and the like.

The adamantane dimethanol, which is an alicyclic dihydroxy compound represented by the general formula (II), includes various isomers in which R ¹ is represented by the following general formula (IIe) in the general formula (II). Specific examples of such a substance include 1,3-adamantane dimethanol and the like.

Further, in the cyclohexanediol which is an alicyclic dihydroxy compound represented by the above general formula (III), in the general formula (III), R ² is the following general formula (IIIa) (in the formula, R ³ has 1 to 1 carbon atoms. Includes various isomers represented by 12 alkyl groups or hydrogen atoms. Specific examples of such a product include 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol and the like.

As the tricyclodecanediol and pentacyclopentadecanediol, which are alicyclic dihydroxy compounds represented by the general formula (III), in the general formula (III), R ² is the following general formula (IIIb) (in the formula, n). Indicates 0 or 1) and includes various isomers represented by).

As a decalin diol or a tricyclotetradecane diol which is an alicyclic dihydroxy compound represented by the general formula (III), in the general formula (III), R ² is the following general formula (IIIc) (in the formula, m is 0). , Or various isomers represented by 1). Specifically, 2,6-decalin diol, 1,5-decalin diol, 2,3-decalin diol and the like are used as such.

The norbornane diol which is an alicyclic dihydroxy compound represented by the general formula (III), in the general formula (III), includes various isomers where R ² is represented by the following general formula (IIId). Specifically, 2,3-norbornanediol, 2,5-norbornanediol and the like are used as such.

The adamantane diol which is an alicyclic dihydroxy compound represented by the general formula (III), in the general formula (III), includes various isomers where R ² is represented by the following general formula (IIIe). Specifically, 1,3-adamantane diol and the like are used as such substances.

Among the specific examples of the alicyclic dihydroxy compounds described above, cyclohexanedimethanol, tricyclodecanedimethanol, adamantandiol, and pentacyclopentadecanedimethanol are particularly preferable, and are easily available and easy to handle. From this point of view, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and tricyclodecanedimethanol are preferable. In the present invention, tricyclodecanedimethanol is preferably used as the dihydroxy compound (B).

Examples of the aliphatic dihydroxy compound that can be used in the present invention include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, and 1,2-butanediol. Examples include diol, 1,5-heptanediol, and 1,6-hexanediol. Examples of oxyalkylene glycols that can be used in the present invention include diethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol.

Examples of the aromatic dihydroxy compound that can be used in the present invention include 2,2-bis (4-hydroxyphenyl) propane [= bisphenol A] and 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-nitro) Phenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 3,3-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) Sulfur, 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, Examples thereof include 9-bis (4-hydroxyphenyl) fluorene and 9,9-bis (4-hydroxy-2-methylphenyl) fluorene.

Examples of diols having a cyclic ether structure that can be used in the present invention include spiroglycols and dioxane glycols. The above-exemplified compound is an example of an alicyclic dihydroxy compound, an aliphatic dihydroxy compound, an oxyalkylene glycol, an aromatic dihydroxy compound, and a diol having a cyclic ether structure that can be used in the present invention. It is not limited. One or more of these compounds can be used together with the dihydroxy compound represented by the formula (4).

By using these dihydroxy compounds (B), effects such as improvement of flexibility, improvement of heat resistance, and improvement of moldability can be obtained according to the application. The ratio of the dihydroxy compound (A), for example, the dihydroxy compound represented by the formula (4) to all the dihydroxy compounds constituting the polycarbonate resin according to the present invention is not particularly limited, but is preferably 10 mol% or more, more preferably 40 mol. % Or more, more preferably 60 mol% or more, preferably 90 mol% or less, more preferably 80 mol% or less, still more preferably 70 mol% or less. If the content ratio of the structural unit derived from other dihydroxy compounds is too large, the performance such as optical characteristics may be deteriorated.

When an alicyclic dihydroxy compound is used among the above other dihydroxy compounds, the dihydroxy compound (A) with respect to all the dihydroxy compounds constituting the polycarbonate, for example, the dihydroxy compound represented by the formula (4) and the alicyclic dihydroxy compound The total ratio is not particularly limited, but is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more.

Further, regarding the content ratio of the dihydroxy compound (A), for example, the structural unit derived from the dihydroxy compound represented by the formula (4) and the structural unit derived from the alicyclic dihydroxy compound in the polycarbonate resin according to the present invention. Although it can be selected in any ratio, the structural unit derived from the dihydroxy compound represented by the formula (4): the structural unit derived from the alicyclic dihydroxy compound = 1: 99 to 99: 1 (mol%) is preferable, and in particular. The structural unit derived from the dihydroxy compound represented by the formula (4): the structural unit derived from the alicyclic dihydroxy compound = 10: 90 to 90:10 (mol%) is preferable. If the number of structural units derived from the dihydroxy compound represented by the formula (4) is larger than the above range and the number of structural units derived from the alicyclic dihydroxy compound is smaller, coloring becomes easier, and conversely, the dihydroxy represented by the formula (4). If the number of structural units derived from the compound is small and the number of structural units derived from the alicyclic dihydroxy compound is large, the molecular weight tends to be difficult to increase.

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

Details of the polycarbonate resin are described in, for example, Japanese Patent Application Laid-Open No. 2012-31370. The description of the patent document is incorporated herein by reference.

C. Method for producing a retardation film The method for producing a retardation film according to the embodiment of the present invention includes stretching a resin film. The resin film is a film formed from the polycarbonate resin described in Section B above.

In one embodiment, the retardation film can be made by biaxial stretching. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. The stretching ratio in the longitudinal direction is preferably more than 1.0 times and 2.0 times or less, and more preferably 1.1 times to 1.5 times. The draw ratio in the width direction is preferably 1.6 times to 2.2 times, more preferably 1.8 times to 2.0 times. By stretching the film formed from the above-mentioned polycarbonate resin at such a stretching ratio, not only desired optical properties but also extremely excellent mechanical properties (for example, deformability and folding resistance) are realized. be able to.

The stretching temperature of the resin film is preferably Tg-30 ° C to Tg + 30 ° C, more preferably Tg-15 ° C to Tg + 15 ° C, and even more preferably Tg-10 ° C to Tg + 10 ° C. By stretching at such a temperature, a retardation film having appropriate characteristics in the present invention can be obtained. Tg is the glass transition temperature of the constituent material of the film.

By selecting the above-mentioned stretching method and stretching conditions and stretching the resin film containing the above-mentioned polycarbonate resin, whitening and cracking are suppressed in the sebum resistance test, and deformability and folding resistance are suppressed. An excellent retardation film can be obtained.

D. Polarizing plate with retardation layer The retardation film according to the above items A to C can be provided as a laminate with another optical film and / or an optical member. In one embodiment, the retardation film can be provided as a laminate with a polarizing plate (polarizing plate with a retardation layer). Therefore, the present invention includes a polarizing plate with a retardation layer having the retardation film. The polarizing plate with a retardation layer according to the embodiment of the present invention includes a polarizing plate and a retardation layer composed of the retardation film. In the retardation film, the angle formed by the absorption axis of the polarizing element of the polarizing plate and the slow axis of the retardation film can be appropriately set according to the application and purpose. In one embodiment, the angle is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and even more preferably about 45 °.

The polarizing plate typically has a polarizing element and a protective layer arranged on at least one side of the polarizing element.

As the polarizer, any suitable polarizer can be adopted. For example, the resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer system partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine and a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical characteristics, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is used.

The dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Moreover, you may dye after stretching. If necessary, the PVA-based film is subjected to a swelling treatment, a cross-linking treatment, a washing treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt on the surface of the PVA-based film and the blocking inhibitor, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. Details of the method for producing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The description of the patent document is incorporated herein by reference. The entire description of the publication is incorporated herein by reference.

In one embodiment, the thickness of the polarizer is preferably 1 μm to 25 μm, more preferably 3 μm to 10 μm, and even more preferably 3 μm to 8 μm. When the thickness of the polarizer is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The protective layer is formed of any suitable protective film that can be used as a film to protect the polarizer. Specific examples of the material that is the main component of the protective film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone. Examples thereof include transparent resins such as polyester-based, polystyrene-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, and acetate-based. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Further, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

The thickness of the protective layer is preferably 10 μm to 100 μm. The protective layer may be laminated on the polarizer via an adhesive layer (specifically, an adhesive layer or an adhesive layer), or may be laminated in close contact with the polarizer (without an adhesive layer). Good. If necessary, a surface treatment layer such as a hard coat layer, an antiglare layer, and an antireflection layer can be formed on the protective layer arranged on the outermost surface of the polarizing plate with a retardation layer.

The polarizing plate with a retardation layer can be used on the visual side of an image display device. Further, the retardation layer in the polarizing plate with a retardation layer may be arranged on the visual recognition side or may be arranged on the display cell side.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method and evaluation method for each characteristic are as follows.
(1) In-plane retardation and wavelength dispersion characteristics The retardation films obtained in Examples and Comparative Examples were cut into lengths of 4 cm and widths of 4 cm and used as measurement samples. For the measurement sample, the in-plane phase difference Re (550) was measured using the product name "Axoscan" manufactured by Axometrics. Furthermore, Re (450) was also measured, and Re (450) / Re (550) was calculated.
(2) Humidity Permeability The retardation films obtained in Examples and Comparative Examples have an area of 1 m ^{2 in} an atmosphere of a temperature of 40 ° C. and a humidity of 92% RH in accordance with the JIS Z0208 moisture permeability test (cup method). The amount of water vapor (g) passing through the sample in 24 hours was measured.
(3) Phase difference change The retardation films obtained in Examples and Comparative Examples are cut into 5 cm × 5 cm pieces, an adhesive is attached to one side with a hand roller, and the adhesive side is attached to one side of alkaline glass. A test piece was obtained by attaching. 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 phase difference change (%) before the start of the test and after the test was calculated.
(4) Deformation workability test The retardation films obtained in Examples and Comparative Examples were irradiated with a CO ₂ laser at an energy of 3 Kw, cut in the flow direction of the film and in the direction perpendicular to the flow direction, and 200 mm × 200 mm. A measurement sample was obtained. The cut portion was observed using a laser microscope, and was marked with 〇 if there were no cracks, and x if there were cracks and / or could not be cut.
(5) Sebum resistance test The retardation films obtained in Examples and Comparative Examples were cut into 5 cm x 5 cm pieces, an adhesive was attached to one side with a hand roller, and the adhesive side was attached to one side of alkaline glass. A test piece was obtained by attaching. The obtained test piece was immersed in an oleic acid solution under the conditions of 65 ° C. and 90% RH for 72 hours, and after being taken out, a transparent one was marked with ◯, and a whitened or cracked one was marked with x.
(6) Number of MITs The MIT test was conducted in accordance with JIS P 8115. Specifically, the retardation films obtained in Examples and Comparative Examples were cut out to a length of 15 cm and a width of 1.5 cm and used as measurement samples. Attach the measurement sample to the MIT folding fatigue tester BE-202 (manufactured by Tester Sangyo Co., Ltd.) (load 1.0 kgf, clamp R: 0.38 mm), and repeatedly bend at a test speed of 90 cpm and a bending angle of 90 °. The test value was the number of bends when the measurement sample broke. Those with experience points of 500 times or more were evaluated as 〇, and those with less than 500 times were evaluated as x.

[Example 1]
1. 1. Preparation of resin film Isosorbide (hereinafter sometimes abbreviated as "ISB") 81.98 parts by mass, tricyclodecanedimethanol (hereinafter sometimes abbreviated as "TCDDM") 47.19 parts by mass, diphenyl 175.1 parts by mass of carbonate (hereinafter sometimes abbreviated as "DPC") and 0.979 parts by mass of a 0.2% by mass aqueous solution of cesium carbonate as a catalyst were put into a reaction vessel, and the reaction was carried out in a nitrogen atmosphere. As the first step of the above, the heating tank temperature was heated to 150 ° C., and the raw materials were dissolved while stirring as necessary (about 15 minutes). Next, the pressure was changed from normal pressure to 13.3 kPa, and the generated phenol was extracted from the reaction vessel while raising the heating tank temperature to 190 ° C. in 1 hour. After holding the entire reaction vessel at 190 ° C. for 15 minutes, as the second step, the pressure inside the reaction vessel is set to 6.67 kPa, the heating tank temperature is raised to 230 ° C. in 15 minutes, and the generated phenol is generated. It was taken out of the reaction vessel. Since the stirring torque of the stirrer increased, the temperature was raised to 250 ° C. in 8 minutes, and the pressure in the reaction vessel was brought to 0.200 kPa or less in order to remove the generated phenol. After reaching a predetermined stirring torque, the reaction was terminated, and the produced reaction product was extruded into water to obtain pellets of a polycarbonate resin. After vacuum-drying the obtained polycarbonate resin at 80 ° C. for 5 hours, a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250 ° C.), T-die (width 300 mm, set temperature: 250 ° C.), chill roll ( A polycarbonate resin film having a thickness of 135 μm was produced using a film-forming device equipped with a set temperature (120 to 130 ° C.) and a winder.

2. 2. Preparation of Phase Difference Film The unstretched polycarbonate resin film was subjected to preheat treatment and simultaneous biaxial stretching using a simultaneous biaxial stretching machine to obtain a retardation film. The preheating temperature was 138.5 ° C., the stretching temperature was 138.5 ° C., the stretching ratio in the longitudinal direction was 1.2 times, and the stretching ratio in the width direction was 1.9 times. Wavelength dispersion value of the obtained retardation film was 1.025, the in-plane retardation Re (550) is 269 nm, the moisture permeability is 80g ^/ m 2 · 24h, the phase difference change is 0.8% Met. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

[Example 2]
The retardation film was the same as in Example 1 except that the preheating temperature was 139 ° C., the stretching temperature was 139 ° C., the stretching ratio in the longitudinal direction was 1.25 times, and the stretching ratio in the width direction was 2.0 times. Got Wavelength dispersion value of the obtained retardation film was 1.021, the in-plane retardation Re (550) is 262 nm, the moisture permeability is 83g ^/ m 2 · 24h, the phase difference change is 0.9% Met. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

[Example 3]
A retardation film was obtained in the same manner as in Example 1 except that the stretching ratio in the longitudinal direction was 1.25 times and the stretching ratio in the width direction was 2.0 times. Wavelength dispersion value of the obtained retardation film was 1.026, the in-plane retardation Re (550) is 279 nm, the moisture permeability is 81g ^/ m 2 · 24h, the phase difference change is 0.8% Met. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

[Example 4]
A retardation film was obtained in the same manner as in Example 1 except that the preheating temperature was 139 ° C. and the stretching temperature was 139 ° C. Wavelength dispersion value of the obtained retardation film was 1.021, the in-plane retardation Re (550) is 271 nm, the moisture permeability is 97g ^/ m 2 · 24h, the phase difference change is 1.0% Met. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

[Example 5]
A retardation film was obtained in the same manner as in Example 1 except that the preheating temperature was 140 ° C. and the stretching temperature was 140 ° C. Wavelength dispersion value of the obtained retardation film was 1.022, the in-plane retardation Re (550) is 230 nm, the moisture permeability is 78g ^/ m 2 · 24h, the phase difference change is 0.8% Met. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

[Example 6]
A retardation film was obtained in the same manner as in Example 1 except that the preheating temperature was 138 ° C. and the stretching temperature was 138 ° C. Wavelength dispersion value of the obtained retardation film was 1.025, the in-plane retardation Re (550) is 300 nm, the moisture permeability is 76g ^/ m 2 · 24h, the phase difference change is 0.8% Met. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

[Comparative Example 1]
The same as in Example 1 except that a commercially available cycloolefin resin film (manufactured by Zeon Corporation, trade name "Zeonoa") was used as the resin film and stretched at a preheating temperature of 180 ° C. and a stretching temperature of 175 ° C. A retardation film was obtained. Wavelength dispersion value of the obtained retardation film was 1.01, in-plane retardation Re (550) is 270 nm, the moisture permeability is 25g ^/ m 2 · 24h, the phase difference change is 0.6% Met. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

[Comparative Example 2]
The rubbing treatment was performed by adjusting the rotation axis of the rubbing roller to be 45 ° counterclockwise with respect to the longitudinal direction of the triacetyl cellulose (TAC) film (manufactured by Fuji Film Co., Ltd.). The rubbing-treated TAC film was coated with a liquid crystal to obtain a liquid crystal-coated triacetyl cellulose (TAC) film. A retardation film was obtained in the same manner as in Example 1 except that this liquid crystal coated TAC film was used as the resin film and no stretching was performed. Wavelength dispersion value of the obtained retardation film was 1.09, in-plane retardation Re (550) is 260 nm, the moisture permeability is 330g ^/ m 2 · 24h, the phase difference change is met 4% It was. The obtained retardation film was subjected to the evaluations (4) to (6) above. The results are shown in Table 1.

As is clear from Table 1, it can be seen that the retardation film of the embodiment of the present invention is excellent in all of the moisture permeability, the retardation change, the deformability test, the sebum resistance test and the MIT test. It is presumed that this is realized by stretching a resin film containing a specific polycarbonate resin under a specific stretching method and stretching conditions.

The retardation film according to the embodiment of the present invention is suitably used for an image display device.

Claims

Contains polycarbonate resin,
Re (450) / Re (550) is 0.98 to 1.03,
Re (550) is 200 nm to 400 nm,
Phase difference film.
The retardation film according to claim 1, wherein the polycarbonate-based resin contains a structural unit derived from a dihydroxy compound represented by the following formula (4).
The polycarbonate resin further contains a structural unit derived from an alicyclic dihydroxy compound.
The alicyclic dihydroxy compound has a structure represented by the following general formula (II), R 1 is represented by the following (II b), and n = 0.
The retardation film according to claim 2.

HOCH 2- R 1- CH 2 OH (II)
The retardation film according to any one of claims 1 to 3, wherein cracks are suppressed in the deformability test.
The retardation film according to any one of claims 1 to 4, wherein whitening and cracking are suppressed in a sebum resistance test.
The retardation film according to claims 1 to 5, wherein the number of MITs is 500 or more.
Moisture permeability is not more than 100g / m 2 · 24h, the phase difference film according to any one of claims 1 to 6.
The retardation film according to any one of claims 1 to 7, wherein the retardation change after storage for 500 hours under the conditions of a temperature of 65 ° C. and a humidity of 90% is 1.0% or less.
A polarizing plate with a retardation layer, which has a retardation layer and a polarizer composed of the retardation film according to any one of claims 1 to 8.
The polarizing plate with a retardation layer according to claim 9, which is used on the visual side of an image display device.