KR20220033422A - Retardation film, polarizing plate with retardation layer, and method for producing retardation film - Google Patents

Abstract

An object of the present invention is to provide a retardation film with suppressed variation in retardation in a humidification reliability test, suppressed variation in hue in a UV weather resistance test, and superior adhesiveness, and a polarizing plate with a retardation layer comprising the same. According to the present invention, the retardation film composed of a resin having birefringence in a predetermined range and having an orientation degree of 30% or more is used.

Description

Retardation film, a polarizing plate having a retardation layer, and a method for manufacturing a retardation film {RETARDATION FILM, POLARIZING PLATE WITH RETARDATION LAYER, AND METHOD FOR PRODUCING RETARDATION FILM}

The present invention relates to a retardation film, a polarizing plate having a retardation layer, and a method for manufacturing the retardation film.

In the recent display market, there is a need to lower the display luminance in order to lengthen the battery endurance and suppress heat generation. For this reason, as a polarizing plate used for a display, the polarizing plate with high light transmittance is calculated|required. However, when such a high polarizing plate of light transmittance is used for a display, there exists a subject that an external appearance deteriorates under humidification conditions.

In addition, in recent years, the use of displays in an environment exposed to ultraviolet light is increasing (eg, PID (Public Information Display), mobile phones), and in particular, in a polarizing plate in which a retardation film is disposed on the panel side, by ultraviolet light There is a problem that the color of the retardation film changes and the quality of the display is impaired.

Japanese Patent No. 3325560 Publication

The present invention has been made in order to solve the above conventional problems, and the object thereof is that the phase difference change in the humidification reliability test is suppressed, the color change in the weather resistance test in the ultraviolet region is suppressed, and the adhesion An object of the present invention is to provide a polarizing plate having an excellent retardation film and a retardation layer comprising the retardation film.

The retardation film in the embodiment of the present invention is composed of a resin having a birefringence Δnxy of 0.015 or more, an orientation degree of 30% or more, and a front retardation Re(550) of 100 nm to 180 nm or 220 nm to 340 nm, 65° C. and 90% RH The change rate of the phase difference after holding for 500 hours is 1.5% or less, and the change rate of the b value in the weather resistance test in the ultraviolet region is 1% or less.

In one embodiment, the said resin contains polycarbonate-type resin.

In one embodiment, the said polycarbonate-type resin contains the structural unit derived from the dihydroxy compound represented by following formula (4).

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

HOCH ₂ -R ¹ -CH ₂ OH (II)

In one embodiment, the thickness of the said retardation film is 10 micrometers - 50 micrometers.

In another embodiment of the present invention, a polarizing plate having a retardation layer is provided. The polarizing plate having this retardation layer includes a polarizer and the retardation film bonded to at least one surface of the polarizer through an adhesive layer. In one embodiment, the retardation film is directly bonded to at least one surface of the polarizer through the adhesive layer. In one embodiment, the said adhesive bond layer is comprised from an active energy ray hardening-type adhesive composition.

According to another aspect of the present invention, a method for manufacturing the retardation film is provided. This manufacturing method includes the process of extending|stretching the resin film formed of the said resin.

According to the embodiment of the present invention, by stretching a resin film composed of a predetermined resin having a birefringence Δnxy of 0.015 or more, the orientation degree becomes a certain value or more, As a result, the phase difference change in the humidification reliability test is suppressed, and the ultraviolet region It is possible to realize a retardation film in which the change in color in the weather resistance test is suppressed.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

(Definition of terms and symbols)

Definitions of terms and symbols in this specification 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 maximum (ie, slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (ie, fast axis direction), and "nz" is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

"Re(λ)" is the in-plane retardation measured with light with a wavelength of λnm at 23°C. For example, “Re(550)” is the in-plane retardation measured with light with a wavelength of 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is d(nm).

(3) birefringence (Δnxy)

Birefringence Δnxy is obtained by the formula: Δnxy=nx-ny.

A. Retardation film

The retardation film according to an embodiment of the present invention contains a polycarbonate resin. Accordingly, the retardation film according to the embodiment of the present invention is typically a stretched film of a polycarbonate resin film. Further, the retardation film according to the embodiment of the present invention preferably does not contain an ultraviolet absorber. When retardation film does not contain a ultraviolet absorber, when it applies to an image display apparatus, it becomes possible to maintain a neutral color.

The birefringence Δnxy of the resin constituting the retardation film is typically 0.015 or more, preferably 0.018 or more. The upper limit of the birefringence Δnxy of the resin may be, for example, 0.040. By stretching the resin having such birefringence ?nxy, a retardation film in which retardation change under humidification conditions is suppressed can be obtained.

The retardation film has an orientation degree of 30% or more, preferably 31% or more, and more preferably 32% or more. The upper limit of the degree of orientation is, for example, 70%. When the orientation degree of retardation film is such a range, the adhesiveness of retardation film becomes favorable. The degree of orientation in this range can be realized by stretching the resin film. The degree of orientation is measured, for example, by X-ray diffraction (XRD).

The in-plane retardation Re (550) of the retardation film is 100 nm to 180 nm or 220 nm to 340 nm, preferably 120 nm to 160 nm or 240 nm to 320 nm. That is, the retardation film can function as a λ/2 retardation plate or a λ/4 retardation plate.

The retardation change of the retardation film after storage (humidification test) for 500 hours under conditions of a temperature of 65°C and a humidity of 90% is preferably 1.5% or less, and more preferably 1.4% or less. The lower limit may be, for example, 0.01%. The phase difference change (%) is | It 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 this range, when the retardation film is applied to an image display device, the color change due to the phase difference for each location on the image display device is small, and the occurrence of color unevenness on the display is suppressed. can get

As for the retardation film, the change in b value is suppressed in the weather resistance test of the ultraviolet region. The rate of change of the b value is 1% or less, preferably 0.95% or less. The lower limit of the change rate of b value is 0%, for example. That is, the retardation film can be favorably used also in applications requiring weather resistance. This advantage can be obtained when the retardation film contains the specific polycarbonate resin mentioned later.

The thickness of the retardation film is preferably 10 µm to 50 µm, and more preferably 20 µm to 40 µm.

The water vapor transmission rate of the retardation 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 may be, for example, 1 g/m ² ·24h. If the water vapor transmission rate of the retardation film is within such a range, the advantage that the change in retardation in a humidified environment can be suppressed can be obtained.

The retardation film has an absolute value of the photoelastic coefficient of 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, still more preferably usually 1.0×10 ^-12 m ² /N to 1.2×10 ^-11 m ² /N. If the absolute value of the photoelastic coefficient is within such a range, a phase difference change is unlikely to occur when a shrinkage stress during heating occurs. As a result, thermal non-uniformity of the obtained image display apparatus can be prevented favorably.

According to the embodiment of the present invention, as described above, by stretching a resin film composed of a resin having a birefringence Δnxy in a specific range, a retardation film having an orientation degree in a specific range can be obtained. The retardation film satisfies the desired in-plane retardation, and the retardation change in the humidification reliability test is suppressed, the color change in the weather resistance test in the ultraviolet region is suppressed, and the adhesion is excellent. Such retardation film can be suitably used for, for example, a PID (Public Information Display) or a mobile phone.

B. Construction Materials

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

(polycarbonate resin)

The polycarbonate resin according to the present invention includes 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 a dihydroxy compound with a diester carbonate in the presence of a polymerization catalyst.

Here, the dihydroxy compound having the bonding structure represented by the structural formula (1) includes a structure having two alcoholic hydroxyl groups and a linking group -CH ₂ -O- in the molecule, and in the presence of a polymerization catalyst, dicarbonate If it is a compound which reacts with ester and can produce|generate a polycarbonate, even if it is a compound of any structure, it is possible to use it, and it does not matter even if it uses multiple types together. Moreover, as a dihydroxy compound used for the polycarbonate resin which concerns on this invention, you may use together the dihydroxy compound which does not have the bonding structure represented by Structural formula (1). Hereinafter, the dihydroxy compound having the bonding structure represented by Structural Formula (1) is referred to as the dihydroxy compound (A), and the dihydroxy compound not having the bonding structure represented by the Structural Formula (1) is referred to as the dihydroxy compound (B). It is sometimes abbreviated as

(dihydroxy compound (A))

The "linking group -CH ₂ -O-" in the dihydroxy compound (A) means a structure in which a molecule is formed by bonding with atoms other than a hydrogen atom. In this coupling group, at least as an atom to which an oxygen atom can bond or an atom to which a carbon atom and an oxygen atom can bond simultaneously, a carbon atom is most preferable. The number of "linking groups -CH ₂ -O-" in the dihydroxy compound (A) is preferably 1 or more, more preferably 2 to 4.

Specifically, as the dihydroxy compound (A), for example, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyl) Roxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxy) Roxyethoxy)-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 A compound having an aromatic group in a side chain and an ether group bonded to an aromatic group in the main chain, as exemplified by ,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-hydro Roxyethoxy)phenyl]propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]butane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]-4-methyl Pentane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]octane, 1,1-bis[4-(2-hydroxyethoxy) cy)phenyl]decane, 2,2-bis[3-bromo-4-(2-hydroxyethoxy)phenyl]propane, 2,2-bis[3-cyclohexyl-4-(2-hydroxyethane) Bis(hydroxyalkoxyaryl)alkanes as exemplified by oxy)phenyl]propane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,1-bis[3-cyclo Bis(hydroxyalkoxyaryl)cyclo as exemplified by hexyl-4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclopentane as exemplified by alkanes, 4,4'-bis(2-hydroxyethoxy)diphenyl ether, and 4,4'-bis(2-hydroxyethoxy)-3,3'-dimethyldiphenyl ether Dihydroxyalkoxydiaryl ethers, 4,4'-bis(2-hydroxyethoxyphenyl)sulfide, 4,4'-bis[4-(2-dihydroxyethoxy)-3-methylphenyl] Bishydroxyalkoxyarylsulfides as exemplified by sulfide, 4,4'-bis(2-hydroxyethoxyphenyl)sulfoxide, 4,4'-bis[4-(2-dihydroxyethane) Bishydroxyalkoxyarylsulfoxides as exemplified by oxy)-3-methylphenyl]sulfoxide, 4,4'-bis(2-hydroxyethoxyphenyl)sulfone, 4,4'-bis[4-( bishydroxyalkoxyarylsulfones as exemplified by 2-dihydroxyethoxy)-3-methylphenyl]sulfone, 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-hydroxy Roxyethoxy)phenyl]propyl]benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, 1,3-bis[4-(2-hydroxyethoxy)phenyl]-5,7- Compounds having a cyclic ether structure such as dimethyl adamantane, anhydrous sugar alcohols represented by dihydroxy compounds represented by the following formula (4) and spiro glycols represented by the following formula (6) are enumerated, and these are independently You may use it, and you may use it in combination of 2 or more type.

These dihydroxy compounds (A) may be used independently and may be used in combination of 2 or more type. In the present invention, examples of the dihydroxy compound represented by the formula (4) include isosorbide, isomannide, and isoidet, which have a stereoisomer relationship, and these may be used alone, 2 You may use it combining more than types.

In addition, among the dihydroxy compounds (A), isosorbide obtained by dehydration condensation of sorbitol, which is abundantly present as a resource and produced from various readily available starches, has ease of acquisition and production, optical properties, and moldability. It is most preferred in terms of In the present invention, isosorbide is preferably used as the dihydroxy compound (A).

(dihydroxy compound (B))

In the present invention, as the dihydroxy compound, a dihydroxy compound (B) that is a dihydroxy compound other than the dihydroxy compound (A) may be used. As the dihydroxy compound (B), for example, an alicyclic dihydroxy compound, an aliphatic dihydroxy compound, an oxyalkylene glycol, an aromatic dihydroxy compound, or a diol having a cyclic ether structure is used in the composition of the polycarbonate. As a dihydroxy compound used as a unit, it can be used together with a dihydroxy compound (A), for example, the dihydroxy compound represented by Formula (4).

Although it does not specifically limit as an alicyclic dihydroxy compound which can be used for this invention, Preferably, the compound containing a 5-membered ring structure or a 6-membered ring structure is used normally. In addition, the 6-membered ring structure may be fixed in a chair shape or a boat shape by a covalent bond. When the alicyclic dihydroxy compound has a 5-membered ring or 6-membered ring structure, the heat resistance of the polycarbonate obtained can be made high. 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. Heat resistance becomes high, so that this value becomes large, but synthesis|combination becomes difficult, refinement|purification becomes difficult, or cost becomes expensive. It is easy to refine|purify and becomes easy to obtain, so that a carbon atom number becomes small.

Specific examples of the alicyclic dihydroxy compound having a 5-membered ring structure or a 6-membered ring structure usable in the present invention include an alicyclic dihydroxy compound represented by the following general formula (II) or (III).

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 cyclohexanedimethanol which is an alicyclic dihydroxy compound represented by the said general formula (II), in general formula (II), R< ¹ > is following general formula (IIa) (wherein, R< ³ > is a C1-C12 represents an alkyl group or a hydrogen atom). Specific examples thereof include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol.

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

As decalindimethanol or tricyclotetradecanedimethanol 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) (wherein m is 0 or 1), and various isomers are included. Specific examples thereof include 2,6-decalin dimethanol, 1,5-decalin dimethanol, and 2,3-decalin dimethanol.

Moreover, as norbornane dimethanol which is an alicyclic dihydroxy compound represented by the said general formula (II), in general formula (II), R< ¹ > includes various isomers represented by the following general formula (IId). Specific examples thereof include 2,3-norbornane dimethanol and 2,5-norbornane dimethanol.

As adamantane dimethanol which is an alicyclic dihydroxy compound represented by general formula (II), in general formula (II), R< ¹ > includes various isomers represented by the following general formula (IIe). Specific examples thereof include 1,3-adamantane dimethanol and the like.

In addition, in the cyclohexanediol which is an alicyclic dihydroxy compound represented by the general formula (III), in the general formula (III), R ² is the following general formula (IIIa) (wherein R ³ is 1 to 12 carbon atoms) represents an alkyl group or a hydrogen atom of). Specific examples thereof include 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2-methyl-1,4-cyclohexanediol and the like.

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

As decalindiol or tricyclotetradecanediol 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) (wherein m is 0 or 1 is included). As such, 2,6-decalindiol, 1,5-decalindiol, 2,3-decalindiol and the like are specifically used.

As norbornane diol which is an alicyclic dihydroxy compound represented by the said general formula (III), in general formula (III), R< ² > includes various isomers represented by the following general formula (IIId). As such, 2,3-norbornanediol, 2,5-norbornanediol, etc. are specifically used.

As adamantane diol which is an alicyclic dihydroxy compound represented by the said general formula (III), in general formula (III), R< ² > includes various isomers represented by the following general formula (IIIe). As such, 1,3-adamantanediol or the like is specifically used.

Among the specific examples of the alicyclic dihydroxy compound described above, cyclohexanedimethanols, tricyclodecanedimethanols, adamantanediols, and pentacyclopentadecanedimethanols are preferable, and availability and handling are particularly preferred. 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and tricyclodecanedimethanol are preferable from a viewpoint of the ease. In the present invention, tricyclodecane dimethanol is preferably used as the dihydroxy compound (B).

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

As the aromatic dihydroxy compound usable in the present invention, 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 and 9,9-bis(4-hydroxy-2-methylphenyl)fluorene are listed.

Examples of the diols having a cyclic ether structure that can be used in the present invention include spiroglycols and dioxane glycols. In addition, the above exemplary compounds are examples of alicyclic dihydroxy compounds, aliphatic dihydroxy compounds, oxyalkylene glycols, aromatic dihydroxy compounds, and diols having a cyclic ether structure that can be used in the present invention, and at least these is not limited to These compounds can be used 1 type, or 2 or more types together with the dihydroxy compound represented by Formula (4).

By using these dihydroxy compounds (B), effects such as improvement of flexibility, improvement of heat resistance and improvement of moldability according to the use can be obtained. 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 Preferably 10 mol% or more, more preferably 40 mol% or more, still more preferably 60 mol% or more, preferably 90 mol% or less, more preferably 80 mol% or less, still more preferably 70 mol% or less am. When there are too many content rates of the structural unit derived from another dihydroxy compound, performance, such as an optical characteristic, may be reduced.

Among the other dihydroxy compounds, when an alicyclic dihydroxy compound is used, the dihydroxy compound (A) for all the dihydroxy compounds constituting the polycarbonate, for example, the dihydroxy compound represented by the formula (4) Although the ratio of the total of a hydroxy compound and an alicyclic dihydroxy compound is not specifically limited, Preferably it is 80 mol% or more, More preferably, it is 90 mol% or more, More preferably, it is 95 mol% or more.

In addition, the dihydroxy compound (A) in the polycarbonate resin according to the present invention, for example, a structural unit derived from a dihydroxy compound represented by formula (4) and an alicyclic dihydroxy compound The content ratio of the structural unit can be selected at any ratio, but structural unit derived from a dihydroxy compound represented by formula (4): structural unit derived from an alicyclic dihydroxy compound = 1:99 to 99: 1 (mol%) is preferable, in particular, structural unit derived from the dihydroxy compound represented by formula (4): structural unit derived from an alicyclic dihydroxy compound = 10:90 to 90:10 (mol%) It is preferable to be If there are more structural units derived from the dihydroxy compound represented by Formula (4) than the above range and fewer structural units derived from the alicyclic dihydroxy compound, the color becomes easier, and conversely, the dihydroxy compound represented by Formula (4) When there are few structural units derived from a hydroxy compound and there are many structural units derived from an alicyclic dihydroxy compound, there exists a tendency for molecular weight to become difficult to become large.

In addition, when using an aliphatic dihydroxy compound, oxyalkylene glycol, an aromatic dihydroxy compound, or a diol having a cyclic ether structure, the dihydroxy compound (A) for all the dihydroxy compounds constituting the polycarbonate ), for example, the ratio of the sum of the dihydroxy compound represented by Formula (4) and each of these dihydroxy compounds is not specifically limited, It can select by arbitrary ratios. In addition, the content ratio of the structural unit derived from the dihydroxy compound (A), for example, the dihydroxy compound represented by formula (4), and the structural units derived from each of these dihydroxy compounds is not particularly limited. and may be selected at any ratio.

The detail of polycarbonate-type resin is described in Unexamined-Japanese-Patent No. 2012-31370 (Japanese Patent No. 5448264), for example. The description of the above patent document is incorporated herein by reference.

C. Manufacturing method of retardation film

The manufacturing method of the retardation film by embodiment of this invention includes the extending|stretching process of a resin film. The resin film is a film formed of the polycarbonate resin described in section B above.

In one embodiment, retardation film is produced by uniaxial stretching or fixed-end uniaxial stretching of a resin film. Specific examples of the fixed-end uniaxial stretching include a method in which the resin film is stretched in the width direction (transverse direction) while running in the longitudinal direction. A draw ratio becomes like this. Preferably they are 1.1 times - 3.5 times, More preferably, they are 1.5 times - 3.0 times, More preferably, they are 2.0 times - 2.5 times. By stretching the resin film formed of the polycarbonate resin according to item B at such a draw ratio, the solvent permeability to the retardation film is changed, a compatible layer with the adhesive layer is formed, and the adhesive force is improved. This phenomenon is so remarkable that the retardation value of retardation film is high. That is, by extending|stretching a specific polycarbonate resin by the above draw ratios, the phase difference change in the humidification condition of retardation film can be suppressed remarkably.

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, still more preferably Tg-10°C to Tg+10°C. . By stretching at such a temperature, a retardation film having suitable properties in the present invention can be obtained. In addition, Tg is the glass transition temperature of the constituent material of a film.

D. Polarizing plate having retardation layer

The retardation film according to the above items A to C may be provided as a laminate with other optical films and/or optical members. In one embodiment, the retardation film may be provided as a laminated body with a polarizing plate (polarizing plate which has retardation layer). Accordingly, the present invention includes a polarizing plate having a retardation layer having the retardation film. A polarizing plate having a retardation layer according to an embodiment of the present invention includes a polarizing plate and a retardation layer composed of the retardation film. In the retardation film, the angle between the absorption axis of the polarizer of the polarizing plate and the slow axis of the retardation film may be appropriately set according to the purpose and purpose. In one embodiment, the angle is preferably 40° to 50°, more preferably 42° to 48°, still more preferably about 45°.

A polarizing plate having a retardation layer typically includes a polarizer and the retardation film bonded to at least one surface of the polarizer through an adhesive layer. As described above, the retardation film has excellent adhesion to the polarizer.

Examples of the adhesive composition constituting the adhesive layer include active energy ray-curable adhesive compositions. The active energy ray-curable adhesive composition contains an active energy ray-curable compound.

The active energy ray-curable adhesive composition according to the present invention is, for example, an active energy ray-curable adhesive composition containing active energy ray-curable compounds (A), (B) and (C) as a curable component, and the total amount of the composition is 100 0.0 to 4.0 wt% of the active energy ray-curable compound (A) having an SP value of 29.0 (MJ/m ³ ) 1/2 or more and 32.0 (MJ/m ³ ) 1/2 or less when taken as a weight %, an SP value of 18.0 (MJ/m ³ ) 1/2 or more and 21.0 (MJ/m ³ ) 1/2 or more of the active energy ray-curable compound (B) in an amount of 5.0 to 98.0% by weight and an SP value of 21.0 (MJ/m ³ ) 1/2 or more 26.0 (MJ/m ³ ) 1/2 or less active energy ray-curable compound (C) is contained in an amount of 5.0 to 98.0% by weight. In addition, in this invention, "composition whole quantity" shall mean the whole quantity containing various initiators and additives in addition to an active energy ray hardening type compound.

The active energy ray-curable compound (A) has a radically polymerizable group such as a (meth)acrylate group, and has an SP value of 29.0 (MJ/m ³ ) 1/2 or more and 32.0 (MJ/m ³ ) 1/2 or less. It can be used without limitation. Specific examples of the active energy ray-curable compound (A) include hydroxyethyl acrylamide (SP value 29.5), N-methylolacrylamide (SP value 31.5), and the like. In addition, in this invention, a (meth)acrylate group means an acrylate group and/or a methacrylate group.

The active energy ray-curable compound (B) has a radically polymerizable group such as a (meth)acrylate group, and a compound having an SP value of 18.0 (MJ/m ³ ) 1/2 or more and 21.0 (MJ/m ³ ) 1/2 or more. It can be used without limitation. Specific examples of the active energy ray-curable compound (B) include, for example, tripropylene glycol diacrylate (SP value 19.0), 1,9-nonanediol diacrylate (SP value 19.2), tricyclodecane dimethanol diacrylate (SP value 20.3), cyclic trimethylolpropane formal acrylate (SP value 19.1), dioxane glycol diacrylate (SP value 19.4), EO modified diglycerin tetraacrylate (SP value 20.9), etc. are mentioned. In addition, as an active energy ray-curable compound (B), a commercial item can also be used suitably, For example, Aronix M-220 (made by TOAGOSEI CO., LTD., SP value 19.0), light acrylate 1,9ND-A ( Kyoeisha Chemical Co., Ltd. production, SP value 19.2), light acrylate DGE-4A (Kyoeisha Chemical Co., Ltd. production, SP value 20.9), light acrylate DCP-A (Kyoeisha Chemical Co., Ltd. production) , SP value 20.3), SR-531 (manufactured by SARTOMER, SP value 19.1), CD-536 (manufactured by SARTOMER, SP value 19.4) and the like.

The active energy ray-curable compound (C) has a radically polymerizable group such as a (meth)acrylate group, and has an SP value of 21.0 (MJ/m ³ ) 1/2 or more and 26.0 (MJ/m ³ ) 1/2 or less. It can be used without limitation. Specific examples of the active energy ray-curable compound (C) include acryloylmorpholine (SP value 22.9), N-methoxymethylacrylamide (SP value 22.9), N-ethoxymethylacrylamide (SP value 22.3) ) are listed. Further, as the active energy ray-curable compound (C), commercially available products can also be suitably used, for example, ACMO (manufactured by Kohjin Co., Ltd., SP value 22.9), Wasmer 2MA (manufactured by Kasano Kosan Co., Ltd., SP value 22.9), Wasmer EMA (manufactured by Kasano Kosan Co., Ltd., SP value 22.3), Wasmer 3MA (manufactured by Kasano Kosan Co., Ltd., SP value 22.4), and the like.

Details of the adhesive composition are described in, for example, Japanese Patent Application Laid-Open No. 2019-147865. The description of the above patent document is incorporated herein by reference. By combining the adhesive layer and the retardation film, a compatible layer is formed between the retardation film and the adhesive layer, and the adhesion of the retardation film is improved. Therefore, preparation of the polarizing plate which has retardation layer WHEREIN: It becomes unnecessary to form an easily bonding layer between retardation film and an adhesive bond layer. Accordingly, in the polarizing plate having the retardation layer, the retardation film is preferably directly bonded to at least one surface of the polarizer through an adhesive layer. In the polarizing plate having the retardation layer that does not have such an easily adhesive layer, the retardation change under humidification conditions can be well suppressed.

You may have a protective layer on at least one surface of the said polarizer. Moreover, you may have an adhesive layer and a separator in the surface on the opposite side to the visual recognition side of the polarizing plate which has the said retardation layer. As for the polarizer, the protective layer, the pressure-sensitive adhesive layer, and the separator, the configuration is well known in the industry and thus detailed description is omitted.

(Example)

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method and evaluation method of each characteristic are as follows.

(1) In-plane phase difference

The retardation film obtained in the Example and the comparative example was cut out to 4 cm in length and 4 cm in width, and it was set as the measurement sample. About the said measurement sample, the in-plane retardation Re (550) was measured using the Axometrics company make, product name "Axoscan".

(2) refractive index and birefringence Δnxy

It measured with an Abbe refractometer (DR-M2, manufactured by ATAGO CO., LTD.). The measurement was performed in 23 degreeC environment.

(3) thickness

The thickness of 10 µm or less was measured using an interference film thickness analyzer (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-9800”). The thickness exceeding 10 μm was measured using a digital micrometer (manufactured by ANRITSU CORPORATION, product name “KC-351C”).

(4) orientation

The degree of orientation was calculated|required by the X-ray diffraction method (XRD) using the retardation film obtained by the Example and the comparative example.

(5) Humidification phase difference change

A polarizing plate having a retardation layer obtained in Examples and Comparative Examples was cut out to 5 cm × 5 cm, an adhesive was applied to one side with a hand roller, and the adhesive side was stuck to one side of alkali glass to obtain a test piece. 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. A thing with a phase difference change of 1.5 % or less was made into favorable, and what exceeded 1.5 % was made into defect.

(6) Parallel color a-value and b-value

The parallel hue a value and the parallel hue b value of the retardation films obtained in Examples and Comparative Examples were calculated|required. The measurement was performed using the spectroscopic altimeter (made by JASCO Corporation, brand name "V-7100"). UV fade tester (device name; UV fade meter tester U48, manufactured by Suga Test Instruments Co., Ltd.) A case in which the change rate of the b value before input and the b value after 100 h input is 1% or less is considered good, and if it exceeds 1%, it is considered defective. did.

(7) Adhesiveness

The retardation film and the polarizer obtained by the Example and the comparative example were bonded together, and the laminated body was obtained. The obtained laminated body was cut out in the magnitude|size of 200 mm parallel to the extending|stretching direction of a polarizer, and 15 mm in an orthogonal direction, and the said laminated body was bonded to the glass plate. Then, an incision is placed between the retardation film and the polarizer with a cutter knife, and the retardation film and the polarizer are peeled at a peeling rate of 1000 mm/min in the 90° C. direction by the Tensilon universal testing machine RTC (manufactured by A&D Company, Limited), and the peeling The strength (N/15 mm) was measured. The case where peeling strength was 1 N/15 mm or more was made into favorable, and the case where it was less than 1 N/15 mm was made into defect.

[Example 1]

1. Preparation of resin film

To 81.98 parts by mass of isosorbide (hereinafter, it may be abbreviated as "ISB"), 47.19 parts by mass of tricyclodecanedimethanol (hereinafter, it may be abbreviated as "TCDDM"), diphenyl carbonate (hereinafter, it may be abbreviated) (sometimes abbreviated as "DPC") 175.1 parts by mass and 0.979 parts by mass of a 0.2 mass % cesium carbonate aqueous solution as a catalyst were put into a reaction vessel, and in a nitrogen atmosphere, as the first step of the reaction, the heating bath temperature was The raw material was dissolved (about 15 minutes) by heating at 150 DEG C and stirring if necessary. Next, the generated phenol was extracted out of the reaction vessel while the pressure was set to 13.3 kPa from the normal pressure and the heating bath temperature was raised to 190°C in 1 hour. After maintaining the entire reaction vessel at 190°C for 15 minutes, as the second step, the pressure in the reaction vessel is set to 6.67 kPa, the heating bath temperature is raised to 230°C for 15 minutes, and the generated phenol is removed from the reaction vessel extracted out. Since the stirring torque of the stirrer increased, the temperature was raised from 8 minutes to 250° C., and the pressure in the reaction vessel was set 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 resulting reactant was extruded into water to obtain polycarbonate resin pellets. The obtained polycarbonate resin had a birefringence Δnxy of 0.015. After vacuum drying the obtained polycarbonate resin at 100 ° C for 12 hours, a single screw extruder (manufactured by SHIBAURA MACHINE CO., LTD., cylinder set temperature: 250 ° C), T-die (width 1700 mm, set temperature: 250 ° C), cast A 90-micrometer-thick polycarbonate resin film was produced using the film film forming apparatus provided with the roll (setting temperature: 60 degreeC) and the winder.

2. Preparation of retardation 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 140 degreeC, the extending|stretching temperature was 138 degreeC, and the draw ratio in the longitudinal direction was made into 2.4 times. The degree of orientation of the obtained retardation film was 31.1%, the in-plane retardation Re(550) was 140 nm, the humidification retardation change rate was 1.21%, and the thickness was 40 micrometers. The obtained retardation film was used for evaluation of said (6) and (7). A result is shown in Table 1.

3. Fabrication of polarizing plate

As the resin substrate, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 µm) having a long Tg of about 75°C was used, and one surface of the resin substrate was corona treated.

Polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (manufactured by The Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosepimer") are mixed in a ratio of 9: 1 PVA-based resin 100 weight What added 13 weight part of potassium iodide to the part was dissolved in water, and the PVA aqueous solution (coating liquid) was prepared.

The PVA-type resin layer with a thickness of 13 micrometers was formed by coating the said PVA aqueous solution on the corona-treated surface of a resin base material, and drying at 60 degreeC, and the laminated body was produced.

The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching treatment).

Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Next, in a dyeing bath (aqueous solution of iodine obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) at a solution temperature of 30° C., the single transmittance (Ts) of the finally obtained polarizer is a predetermined value. It was immersed for 60 seconds while adjusting the concentration as much as possible (dyeing treatment).

Then, it was immersed for 30 seconds in a crosslinking bath (a boric acid aqueous solution obtained by mix|blending 3 weight part of potassium iodide with respect to 100 weight part of water, and mix|blending 5 weight part of boric acid) with a liquid temperature of 40 degreeC (crosslinking process).

Thereafter, while the laminate is immersed in an aqueous boric acid solution (boric acid concentration of 4 wt%, potassium iodide concentration of 5 wt%) at a liquid temperature of 70 ° C. It uniaxially stretched as much as possible (underwater stretching process).

Then, the laminated body was immersed in the washing|cleaning bath (aqueous solution obtained by mix|blending 4 weight part of potassium iodide with respect to 100 weight part of water) with a liquid temperature of 20 degreeC (washing process).

Thereafter, while drying in an oven maintained at about 90°C, it was brought into contact with a heating roll made of SUS whose surface temperature was maintained at about 75°C (dry shrinkage treatment).

In this way, a polarizer having a thickness of about 5 µm was formed on the resin substrate to obtain a polarizing plate having a configuration of the resin substrate/polarizer.

In addition, a cycloolefin-based film (manufactured by Zeon Corporation, trade name "Zeonor") was bonded to the surface on the opposite side to the resin base material of the obtained polarizer through an ultraviolet curing adhesive as a protective layer. Specifically, it applied so that the total thickness of a curable adhesive might be set to about 1.0 micrometer, and it joined using the roll machine. Thereafter, UV rays were irradiated from the cycloolefin-based film side to cure the adhesive. Next, the resin base material was peeled, and the polarizing plate which has a structure of a cycloolefin type film (protective layer)/polarizer was obtained. The in-plane retardation of the protective layer was 135 nm. The angle between the slow axis of the protective layer and the absorption axis of the polarizer was substantially parallel to each other.

4. Fabrication of a polarizing plate having a retardation layer

On one side of the retardation film, using an MCD coater (manufactured by FUJI MACHINERY Co., Ltd.), an active energy ray-curable adhesive composition was coated to a thickness of 0.7 μm, and the polarizer surface of the polarizing plate was bonded with a roll machine. The active energy ray-curable adhesive composition is "light acrylate 1.9ND-A", Kyoeisha Chemical Co., Ltd. Production of 40 copies, 「Aronix M-5700」, TOAGOSEI CO., LTD. Production of 20 copies, trade name 「ARUFON UP1190」TOAGOSEI CO., LTD. Preparation was obtained by mixing 10 parts of each component and stirring at 50 degreeC for 1 hour. Then, from the side of the retardation film bonded, after irradiating visible light with an active energy ray irradiation apparatus and hardening an active energy ray hardening-type adhesive agent, it hot-air-dried at 70 degreeC for 3 minutes, and obtained the polarizing plate which has a retardation layer. The angle between the absorption axis of the polarizer and the slow axis of the retardation film was set to 45°. The polarizing plate which has the obtained retardation layer was used for evaluation of said (5). A result is shown in Table 1.

[Example 2]

Except having set thickness to 30 micrometers, it carried out similarly to Example 1, and obtained retardation film. The degree of orientation of the obtained retardation film was 31.9%, the in-plane retardation Re(550) was 140 nm, and the humidification retardation change rate was 1.15%. Moreover, similarly to Example 1, the polarizing plate which has a retardation layer was obtained using the obtained retardation film. The obtained retardation film and the polarizing plate which has retardation layer were subjected to the same evaluation in Example 1. A result is shown in Table 1.

[Example 3]

A retardation film was obtained in the same manner as in Example 1 except that the birefringence Δnxy of the polycarbonate resin was 0.018, the preheating temperature was 138°C, and the stretching temperature was 135°C. The degree of orientation of the obtained retardation film was 35.7%, the in-plane retardation Re(550) was 270 nm, and the humidification retardation change rate was 1.29%. Moreover, similarly to Example 1, the polarizing plate which has a retardation layer was obtained using the obtained retardation film. The polarizing plate having the obtained retardation film and retardation layer was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Example 4]

Same as Example 1 except that the birefringence Δnxy of the polycarbonate resin was 0.024, the thickness was 30 μm, the draw ratio was 2.5 times, the preheating temperature was 138°C, and the stretching temperature was 135°C to obtain a retardation film. The degree of orientation of the obtained retardation film was 34.6%, the in-plane retardation Re(550) was 260 nm, and the humidification retardation change rate was 1.31%. Moreover, similarly to Example 1, the polarizing plate which has a retardation layer was obtained using the obtained retardation film. The polarizing plate having the obtained retardation film and retardation layer was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 1]

A retardation 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 draw ratio in the longitudinal direction was set to 2.12. The degree of orientation of the obtained retardation film was 29.4%, the in-plane retardation Re(550) was 140 nm, and the humidification retardation change rate was 2.81%. Moreover, the polarizing plate which has a retardation layer was produced using the retardation film obtained by carrying out similarly to Example 1 except having formed the easily bonding layer. The polarizing plate having the obtained retardation film and retardation layer was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 2]

The retardation was carried out in the same manner as in Example 1 except that a cycloolefin-based resin film having a birefringence Δnxy of 0.021 (manufactured by Zeon Corporation, trade name “Zeonor”) was used, and the preheating temperature was 150°C and the stretching temperature was 148°C. got a film. The degree of orientation of the obtained retardation film was 30.1%, the in-plane retardation Re(550) was 140 nm, and the humidification retardation change rate was 1.2%. Moreover, the polarizing plate which has a retardation layer was produced using the retardation film obtained by carrying out similarly to Example 1 except having formed the easily bonding layer. The polarizing plate having the obtained retardation film and retardation layer was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 3]

(Polymerization of polyester carbonate-based resin)

The polymerization was carried out using a batch polymerization apparatus comprising two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 mass Parts (0.139 mol), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19×10 ^-2 parts by mass (6.78×10 ^-5 mol) of calcium acetate monohydrate were added as a catalyst. After replacing the inside of the reactor with reduced pressure nitrogen, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100°C. The internal temperature was made to reach 220 degreeC 40 minutes after the start of temperature increase, and while controlling so that this temperature might be maintained, pressure reduction was started, and it was set as 13.3 kPa in 90 minutes after reaching 220 degreeC. The phenol vapor produced by the polymerization reaction was guided to a reflux condenser at 100° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the phenol vapor that was not condensed was guided to a condenser at 45° C. and recovered. After nitrogen was introduced into the first reactor and the pressure was returned to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature increase and pressure reduction in the 2nd reactor were started, and it was set as the internal temperature of 240 degreeC and the pressure of 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined stirring power was reached. When a predetermined power was reached, nitrogen was introduced into the reactor and the pressure was restored, the resulting polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets. The obtained polycarbonate resin had a birefringence Δnxy of 0.012.

(Production of retardation film)

After vacuum drying the obtained polyester carbonate-based resin (pellet) at 100° C. for 12 hours, a single screw extruder (manufactured by SHIBAURA MACHINE CO., LTD., cylinder set temperature: 270° C.), T-die (width 1700 mm, set temperature: 270 degreeC), a cast roll (setting temperature: 75 degreeC), and the film film forming apparatus provided with the winder were used, and the 130-micrometer-thick long resin film was produced. The obtained elongate resin film was extended|stretched, adjusting so that a predetermined|prescribed retardation might be obtained, and the 40-micrometer-thick retardation film was obtained. The stretching conditions were in the longitudinal direction, and the stretching ratio was 2.12 times. The degree of orientation of the obtained retardation film was 28.8%, the in-plane retardation Re(550) was 140 nm, and the humidification retardation change rate was 3.1%. Moreover, the polarizing plate which has a retardation layer was produced using the retardation film obtained by carrying out similarly to Example 1 except having formed the easily bonding layer. The polarizing plate having the obtained retardation film and retardation layer was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

[Comparative Example 4]

10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, trade name "Paliocolor LC242", represented by the following formula) and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name "Ilgacure 907") 3 g was melt|dissolved in 40 g of toluene, and the liquid crystal composition (coating liquid) was prepared. The birefringence Δnxy of the liquid crystal composition was 0.004.

The liquid-crystal layer was formed by coating the said liquid-crystal coating liquid on the surface of a polyethylene terephthalate (PET) film with a bar coater, and heat-drying at 90 degreeC for 2 minute(s). The formed liquid crystal layer was irradiated with light of 1 mJ/cm ² using a metal halide lamp, and the liquid crystal layer was cured to form a liquid crystal solidified layer on the PET film. The liquid crystal solidified layer was peeled from PET film, and retardation film was obtained. The obtained retardation film had an in-plane retardation Re(550) of 140 nm, a humidification retardation change rate of 2%, and a thickness of 2 µm. Moreover, the polarizing plate which has a retardation layer was obtained using the retardation film obtained similarly to Example 1. The polarizing plate having the obtained retardation film and retardation layer was subjected to the same evaluation as in Example 1. A result is shown in Table 1.

As is clear from Table 1, it is confirmed that the retardation film of Examples of the present invention is excellent in all of the humidification retardation change rate, weather resistance and adhesiveness. It is estimated that this is realized by extending|stretching the resin film containing specific polycarbonate resin on specific extending|stretching conditions. In addition, in the evaluation of the change in humidification retardation, it is confirmed that the retardation film without an easily adhesive layer is suppressed in the change in humidification retardation as compared with the retardation film having an easily adhesive layer (Comparison of Example 1 and Comparative Example 1) . Moreover, from the comparison of Examples 1-4 and Comparative Example 4, it is confirmed that the color change in a weather resistance test is suppressed by using the retardation film which does not contain a ultraviolet absorber.

(Industrial Applicability)

The polarizing plate which has the retardation film and retardation layer by embodiment of this invention is used suitably for an image display apparatus.

Claims (9)

A retardation film composed of a resin having a birefringence Δnxy of 0.015 or more, the degree of orientation is 30% or more, the front retardation Re (550) is 100 nm to 180 nm or 220 nm to 340 nm, and the retardation change rate after holding at 65° C. and 90% RH for 500 hours This is 1.5 % or less, and the retardation film whose rate of change of b value in the weather resistance test of an ultraviolet region is 1 % or less. The method of claim 1,
The retardation film wherein the resin comprises a polycarbonate-based resin. 3. The method of claim 2,
The retardation film in which the said polycarbonate-type resin contains the structural unit derived from the dihydroxy compound represented by following formula (4).

4. The method of claim 3,
The polycarbonate-based resin further includes a structural unit derived from an alicyclic dihydroxy compound, wherein the alicyclic dihydroxy compound is represented by the following general formula (II), and R ¹ is represented by the following (IIb) structure, and n = 0 retardation film.
HOCH ₂ -R ¹ -CH ₂ OH (II)

The method of claim 1,
A retardation film having a thickness of 10 μm to 50 μm. A polarizing plate having a polarizer and a retardation layer comprising the retardation film according to any one of claims 1 to 5 bonded to at least one surface of the polarizer through an adhesive layer. 7. The method of claim 6,
A polarizing plate having, on at least one surface of the polarizer, a retardation layer to which the retardation film is directly bonded through the adhesive layer. 7. The method of claim 6,
A polarizing plate having a retardation layer in which the adhesive layer is composed of an active energy ray-curable adhesive composition. A method for producing the retardation film according to any one of claims 1 to 5, comprising the step of stretching a resin film formed of the resin.