WO2022018940A1

WO2022018940A1 - Retardation film and method for manufacturing same

Info

Publication number: WO2022018940A1
Application number: PCT/JP2021/018319
Authority: WO
Inventors: 貞裕中西
Original assignee: 日東電工株式会社
Priority date: 2020-07-20
Filing date: 2021-05-14
Publication date: 2022-01-27
Also published as: JP2022020349A; TW202214443A

Abstract

Provided are: a retardation film that has little change in phase difference in heated environments, humidified environments, and after contact with solvents, and that also has excellent solvent resistance; and a method for manufacturing the retardation film. The retardation film according to an embodiment of the present invention comprises a first cured layer, a retardation layer, and a second cured layer, in that order. The retardation layer is formed from a stretched resin film, and the stretched resin film includes a resin containing at least one binding group chosen from carbonate bonds and ester bonds. In the first cured layer and the second cured layer, a cross-linking agent that has a carbon–carbon double bond and the resin included in the stretched resin film are cross-linked via the carbon–carbon double bond.

Description

Phase difference film and its manufacturing method

The present invention relates to a retardation film and a method for manufacturing the same.

In recent years, with the spread of thin displays, displays equipped with organic EL panels have been proposed. The organic EL panel has a highly reflective metal layer, and tends to cause problems such as external light reflection and / or background reflection. Therefore, it is known to prevent these problems by using a circularly polarizing plate having a λ / 4 plate on the visual recognition side. The retardation film used for the circularly polarizing plate has a problem that a retardation change occurs in a heating environment and / or a humidifying environment. Further, the retardation film has a problem that the retardation change occurs even when it comes into contact with a solvent.

Japanese Unexamined Patent Publication No. 2006-171235

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to have a small phase difference change even in a heating environment and a humidified environment, and further, a phase difference change even when in contact with a solvent. It is an object of the present invention to provide a small retardation film and a simple manufacturing method thereof.

The retardation film according to the embodiment of the present invention includes a first cured layer, a retardation layer, and a second cured layer in this order, and the retardation layer is formed of a stretched resin film. Contains a resin containing at least one bonding group selected from carbonate and ester bonds, with a cross-linking agent having a carbon-carbon double bond in the first cured layer and the second cured layer. The resin is crosslinked via the carbon-carbon double bond.
In one embodiment, the resin comprises a structural unit represented by the following formula.

In one embodiment, the resin comprises a structural unit represented by the following formula.

In one embodiment, the retardation film satisfies the relationship Re (450) <Re (550) <Re (650).
In one embodiment, the retardation film satisfies the relationship 0.7 <Re (450) / Re (550) <1.0.
In one embodiment, the Re (550) of the retardation film is 100 nm to 180 nm or 220 nm to 330 nm.
In the aspect where the circularly polarizing plate is provided, the circularly polarizing plate includes the above-mentioned retardation film and a polarizing element.
According to another aspect of the present invention, an image display device is provided. This image display device includes the retardation film. In another embodiment, the image display device comprises the circularly polarizing plate.
According to another aspect of the present invention, there is provided a method for manufacturing the above retardation film. This production method includes a step of cross-linking the resin and the cross-linking agent via the carbon-carbon double bond of the cross-linking agent using a radical generator.
In one embodiment, the radical generator is a hydrogen abstraction type photoradical generator.
In one embodiment, the radical generator is a hydrogen abstraction type thermal radical generator.

The retardation film according to the embodiment of the present invention includes a first cured layer, a retardation layer, and a second cured layer in this order. The retardation layer is formed from a stretched resin film, which comprises a resin containing at least one binding group selected from carbonate and ester bonds. Further, in the first cured layer and the second cured layer, the cross-linking agent having a carbon-carbon double bond and the resin contained in the stretched resin film are cross-linked via the carbon-carbon double bond. There is. In the retardation film according to the embodiment of the present invention, the retardation layer and the first cured layer and the second cured layer are crosslinked as described above, so that even in a heating environment and a humidified environment. It is possible to obtain a retardation film having a small retardation change and a small retardation change even when in contact with a solvent.

FIG. 3 is a schematic cross-sectional view of a retardation film according to one embodiment of the present invention.

Hereinafter, typical 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 refractive index in the plane is maximized (that is, the direction of the slow phase axis), and "ny" is the direction orthogonal to the slow phase axis in the plane (that is, the direction of the phase advance axis). 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) Angle When referring to an angle herein, the angle includes both clockwise and counterclockwise with respect to the reference direction. Therefore, for example, "45 °" means ± 45 °.

A. Overall Configuration of Phase Difference Film FIG. 1 is a schematic cross-sectional view of a retardation film according to one embodiment of the present invention. The retardation film 100 of the illustrated example has a first cured layer 10, a retardation layer 20, and a second cured layer 30 in this order. The retardation layer is formed from a stretched resin film, the stretched resin film containing a resin containing at least one binding group selected from carbonate and ester bonds. In the first cured layer and the second cured layer, the cross-linking agent having a carbon-carbon double bond and the resin contained in the stretched resin film are cross-linked via the carbon-carbon double bond. As a result, the first cured layer and the second cured layer can be formed in the vicinity of the surfaces on both sides of the retardation layer. More specifically, in the retardation film, the central portion of the retardation layer in the thickness direction is composed of the above-mentioned resin which is not crosslinked or has a small degree of cross-linking, and as a result of the above-mentioned resin near the surface being crosslinked, the first cured layer and the first cured layer. It is presumed that the hardened layer of 2 is formed. That is, the first cured layer and the second cured layer are formed from the resin contained in the retardation layer. By having such a structure, the retardation film has an advantage that the phase difference change is small in a heating environment, a humidifying environment, and after contact with a solvent, and further, it is excellent in solvent resistance. Note that FIG. 1 is a schematic diagram, and for convenience, the interface between the first cured layer, the stretched resin film, and the second cured layer is clearly shown. However, in reality, there is no clear interface, and it is presumed that the first cured layer, the stretched resin film, and the second cured layer may have a gradation structure.

The gel fraction of the retardation film is preferably 90% or more, more preferably 95% or more, and further preferably 97% to 99%. It is presumed that such a gel fraction is realized because the first cured layer and the second cured layer substantially prevent the solvent from entering the retardation layer. As described above, it is presumed that the central portion of the retardation layer in the thickness direction is uncrosslinked or is composed of the above resin having a small degree of crosslinking. Is not reflected. The gel fraction can be calculated from the weight of the sample before and after immersing the sample prepared from the retardation film in a predetermined solvent (for example, toluene).

In one embodiment, the cross-linking may be cross-linking between structural units derived from the isosorbide-based dihydroxy compound in the resin contained in the retardation layer. Further, in one embodiment, the first cured layer and the second cured layer may be cross-linked via a carbon-carbon bond between the cross-linking agent and the structural unit derived from the isosorbide-based dihydroxy compound in the above resin. .. As an example, the structure of a reaction product in which structural units derived from the isosorbide dihydroxy compound are crosslinked via a carbon-carbon double bond of a crosslinking agent is shown below. Further, the structure of the cross-linking agent used in the cross-linking reaction is shown below.

Such a crosslinked structure can be formed (by post-crosslinking) by performing a crosslinking treatment after producing a stretched resin film. In one embodiment, a polyethylene terephthalate (PET) film is roll-laminated on both sides of a stretched resin film via a reactive composition containing a cross-linking agent and a radical generator. By performing a crosslinking reaction on the obtained laminate and further peeling off the PET film, a first cured layer and a second cured layer are formed on the surface of the stretched resin film (phase difference layer), and the present invention A retardation film according to the above embodiment can be obtained. In another embodiment, the surface of the stretched resin film is coated with a reactive composition containing a cross-linking agent, a radical generator (with a diluting solvent if necessary), and then heat-treated as necessary. A cured layer can be obtained by carrying out a cross-linking reaction (by heat or UV irradiation) in a nitrogen atmosphere. By applying this operation to both sides of the stretched resin film, a first cured layer and a second cured layer are formed on the surface of the stretched resin film (phase difference layer), and a retardation film according to the embodiment of the present invention is obtained. Be done. In forming such a crosslinked structure, the resin forming the stretched resin film does not need to contain a crosslinkable group. When a stretched resin film is manufactured using a resin containing a crosslinkable group, problems such as gelation of the resin may occur in the manufacturing process (for example, kneading, extrusion, stretching). According to the embodiment of the present invention, it is possible to manufacture a retardation film having a first cured layer and a second cured layer without causing such a problem. Further, according to the post-crosslinking according to the embodiment of the present invention, the retardation film can be produced according to the embodiment of the present invention without modifying the normal retardation film and the process for producing the retardation film. .. In this respect, the invention of the present application has an excellent effect.

The retardation film (substantially, the retardation layer) preferably satisfies the relationship of Re (450) <Re (550) <Re (650). Further, the retardation film preferably satisfies the relationship of 0.7 <Re (450) / Re (550) <1.0. That is, the retardation film exhibits a reverse wavelength dispersion characteristic in which the retardation value increases according to the wavelength of the measured light. When the retardation film has such characteristics, very excellent antireflection characteristics can be realized.

The retardation film (substantially, the retardation layer) preferably has Re (550) of 100 nm to 180 nm or 220 nm to 330 nm, and more preferably Re (550) of 120 nm to 180 nm. Alternatively, it is 240 nm to 310 nm.

As the thickness of the retardation film, any appropriate thickness can be adopted depending on the desired Re (550). The thickness of the retardation film is preferably 20 μm to 100 μm, more preferably 30 μm to 60 μm. The thickness indicates the total thickness of the retardation layer and the first cured layer and the second cured layer.

The retardation film (substantially, the retardation layer) has an internal haze of preferably 3% or less, more preferably 2% or less, still more preferably 1% or less. The lower limit of the internal haze can be substantially 0%. If the internal haze is in such a range, excellent transparency of the retardation film can be realized.

The photoelastic coefficient of the retardation film (substantially the retardation layer) is preferably 1 × 10 ^-12 (m ² / N) to 40 × 10 ^-12 (m ² / N), more preferably. ^{^{1 × 10 -12 (m 2 /}} N) ~ 30 × 10 -12 (m 2 / N) deli, more preferably ^{^{1 × 10 -12 (m 2 /}} N) ~ 20 × 10 -12 (m 2 / N).

A-1. Phase difference layer The retardation layer can be formed from a stretched resin film. The stretched resin film can be obtained by stretching the resin film. The resin film contains a resin containing at least one bonding group of carbonate bond and ester bond. Examples of the resin include a polycarbonate resin, a polyester carbonate resin, a polyester resin, a polyarylate resin, and an acrylic resin. These resins may be used alone or in combination (eg, blending, copolymerization). Among these resins, a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, may be simply referred to as a polycarbonate-based resin) is preferably used.

As the above-mentioned polycarbonate-based resin, any suitable polycarbonate-based resin can be used as long as the effects of the present invention can be obtained. For example, the polycarbonate-based resin preferably contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, an alicyclic dimethanol, di, tri or polyethylene glycol. Also included are structural units derived from at least one dihydroxy compound selected from the group consisting of alkylene glycols or spiroglycols. More preferably, the polycarbonate-based resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and / or di, tri or polyethylene glycol. Containing structural units derived from; more preferably, structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from di, tri or polyethylene glycol. include. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds, if necessary. Details of the polycarbonate-based resin that can be suitably used for the present invention are, for example, JP-A-2014-10291, JP-A-2014-226666, JP-A-2015-21816, JP-A-2015-21217. , Japanese Patent Application Laid-Open No. 2015-21218, and the description is incorporated herein by reference.

Examples of the structural unit derived from the fluorene-based dihydroxy compound include structural units represented by the following formulas. The structural unit may be referred to as an oligofluorene structural unit.

In the general formula (1) and the general formula (2), R ¹ to R ³ are alkylene groups having 1 to 4 carbon atoms which may independently have a direct bond and a substituent, respectively, and are R. ⁴ to R ⁹ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 4 to 10 carbon atoms which may have a substituent, and a substituent. An acyl group having 1 to 10 carbon atoms which may have a group, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, and 1 to 10 carbon atoms which may have a substituent. An aryloxy group, an acyloxy group having 1 to 10 carbon atoms which may have a substituent, an amino group which may have a substituent, and a vinyl having 1 to 10 carbon atoms which may have a substituent. A group, an ethynyl group having 1 to 10 carbon atoms which may have a substituent, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group. However, ^{at least two adjacent groups of R 4} to R ⁹ may be bonded to each other to form a ring. ^{Further, the two R 4} , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ included in the general formula (1) may be the same or different from each other. ^{Similarly, the two R 4} , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ included in the general formula (2) may be the same as or different from each other.

In R ¹ and R ² , for example, the following alkylene groups can be adopted as the "alkylene group having 1 to 4 carbon atoms which may have a substituent". Linear alkylene group such as methylene group, ethylene group, n-propylene group, n-butylene group; methylmethylene group, dimethylmethylene group, ethylmethylene group, propylmethylene group, (1-methylethyl) methylene group, 1 -Methylethylene group, 2-methylethylene group, 1-ethylethylene group, 2-ethylethylene group, 1-methylpropylene group, 2-methylpropylene group, 1,1-dimethylethylene group, 2,2-dimethylpropylene group , A alkylene group having a branched chain, such as a 3-methylpropylene group. Here, ^{the positions of the branched chains in R 1} and R ² are indicated by the numbers assigned so that the carbon on the fluorene ring side is at the 1st position.

The choice of R ¹ and R ² has a particularly important effect on the development of reverse wavelength dispersibility. The resin exhibits the strongest reverse wavelength dispersibility in a state where the fluorene ring is oriented perpendicular to the main chain direction (stretching direction). In order to bring the orientation state of the fluorene ring closer to the above state and to exhibit strong reverse wavelength dispersibility, it is preferable to adopt ^{R 1} and R ^{2 having 2 to 3 carbon atoms on the main chain of the alkylene group.} .. When the number of carbon atoms is 1, unexpectedly, the reverse wavelength dispersibility may not be exhibited. The reason for this is that the orientation of the fluorene ring is fixed in a direction that is not perpendicular to the main chain direction due to steric hindrance of the carbonate group and / or ester group that are the linking groups of the oligofluorene structural unit. Conceivable. On the other hand, when the number of carbon atoms is too large, the fixation of the orientation of the fluorene ring is weakened, which may weaken the reverse wavelength dispersibility. In addition, the heat resistance of the resin is also reduced.

As shown in the general formulas (1) and (2), in R ¹ and R ² , one end of the alkylene group is bonded to the fluorene ring and the other end is either an oxygen atom or a carbonyl carbon contained in the linking group. It is bound to the crab. From the viewpoint of thermal stability, heat resistance and reverse wavelength dispersibility, it is preferable that the other end of the alkylene group is bonded to the carbonyl carbon.

Further, from the viewpoint of facilitating production, it is preferable to use the same alkylene group for ^{R 1} and R ^2.

In R ^3, the term "alkylene group having 1 to carbon atoms which may have a substituent 4" may be employed for example, the following alkylene groups. Linear alkylene group such as methylene group, ethylene group, n-propylene group, n-butylene group; methylmethylene group, dimethylmethylene group, ethylmethylene group, propylmethylene group, (1-methylethyl) methylene group, 1 -Methylethylene group, 2-methylethylene group, 1-ethylethylene group, 2-ethylethylene group, 1-methylpropylene group, 2-methylpropylene group, 1,1-dimethylethylene group, 2,2-dimethylpropylene group , A alkylene group having a branched chain such as a 3-methylpropylene group.

R ³ preferably has 1 to 2 carbon atoms on the main chain of the alkylene group, and particularly preferably 1 carbon atom. ^{When R 3} having too many carbon atoms on the main chain is adopted ^{, the immobilization of the fluorene ring is weakened as in R 1} and R ² , the reverse wavelength dispersibility is lowered, the photoelastic coefficient is increased, and the heat resistance is lowered. Etc. may be invited. On the other hand, the smaller the number of carbon atoms on the main chain, the better the optical properties and / or heat resistance, but when the 9-positions of the two fluorene rings are directly connected by a direct bond, the thermal stability deteriorates.

In R ¹ to R ³ , the substituents exemplified below may be adopted as the substituents that the alkylene group may have, but substituents other than these may be adopted. Halogen atom selected from fluorine atom, chlorine atom, bromine atom and iodine atom; alkoxy group having 1 to 10 carbon atoms such as methoxy group and ethoxy group; acyl group having 1 to 10 carbon atoms such as acetyl group and benzoyl group; Acylamino groups having 1 to 10 carbon atoms such as acetoamide groups and benzoylamide groups; nitro groups; cyano groups; 1 to 1 to the halogen atoms, the alkoxy groups, the acyl groups, the acylamino groups, the nitro groups, the cyano groups and the like. An aryl group having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group, wherein three hydrogen atoms may be substituted.

The number of the substituents is not particularly limited, but is preferably 1 to 3. When there are two or more substituents, the types of substituents may be the same or different. If the number of substituents is too large, the reaction may be inhibited or pyrolysis may occur during the polymerization. Further, from the viewpoint of industrially inexpensive production, it is preferable that ^{R 1} to R ^{3 are unsubstituted.}

In R ⁴ to R ⁹ , for example, the following alkyl groups can be adopted as the "alkyl group having 1 to 10 carbon atoms which may have a substituent". Linear alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl, n-decyl; isopropyl group, 2-methylpropyl group, 2,2- An alkyl group having a branched chain such as a dimethylpropyl group and a 2-ethylhexyl group; a cyclic alkyl group such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group and a cyclooctyl group.

The number of carbon atoms of the alkyl group is preferably 4 or less, and more preferably 2 or less. When the number of carbon atoms of the alkyl group is within this range, steric hindrance between fluorene rings is unlikely to occur, and desired optical properties derived from the fluorene ring tend to be obtained.

As the substituent that the alkyl group may have, the substituents exemplified below can be adopted, but substituents other than these may be adopted. Halogen atom selected from fluorine atom, chlorine atom, bromine atom and iodine atom; alkoxy group having 1 to 10 carbon atoms such as methoxy group and ethoxy group; acyl group having 1 to 10 carbon atoms such as acetyl group and benzoyl group; Acylamino groups having 1 to 10 carbon atoms such as acetoamide groups and benzoylamide groups; nitro groups; cyano groups; 1 to 1 to the halogen atoms, the alkoxy groups, the acyl groups, the acylamino groups, the nitro groups, the cyano groups and the like. An aryl group having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group, wherein three hydrogen atoms may be substituted.

The number of the substituents is not particularly limited, but is preferably 1 to 3. When there are two or more substituents, the types of substituents may be the same or different. If the number of such substituents is too large, the reaction may be inhibited or pyrolysis may occur during the polymerization. Further, from the viewpoint of industrially inexpensive production, it is preferable that ^{R 4} to R ^{9 are unsubstituted.}

Specific examples of the alkyl group include a trifluoromethyl group, a benzyl group, a 4-methoxybenzyl group, a methoxymethyl group and the like.

Further, in R ⁴ to R ⁹ , for example, the following aryl group can be adopted as the "aryl group having 4 to 10 carbon atoms which may have a substituent". Aryl groups such as phenyl group, 1-naphthyl group and 2-naphthyl group; heteroaryl groups such as 2-pyridyl group, 2-thienyl group and 2-furyl group.

The aryl group preferably has 8 or less carbon atoms, and more preferably 7 or less carbon atoms. When the number of carbon atoms of the aryl group is within this range, steric hindrance between the fluorene rings is unlikely to occur, and the desired optical properties derived from the fluorene ring tend to be obtained.

In R ⁴ to R ⁹ , the substituents exemplified below may be adopted as the substituents that the aryl group may have, but substituents other than these may be adopted. Halogen atom selected from fluorine atom, chlorine atom, bromine atom and iodine atom; alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group and isopropyl group; Alkoxy group; acyl group having 1 to 10 carbon atoms such as acetyl group and benzoyl group; acylamino group having 1 to 10 carbon atoms such as acetamide group and benzoylamide group; nitro group; cyano group. The number of the substituents is not particularly limited, but is preferably 1 to 3. When there are two or more substituents, the types of substituents may be the same or different. Further, from the viewpoint of industrially inexpensive production, it is preferable that ^{R 4} to R ^{9 are unsubstituted.}

Specific examples of the aryl group include 2-methylphenyl group, 4-methylphenyl group, 3,5-dimethylphenyl group, 4-benzoylphenyl group, 4-methoxyphenyl group, 4-nitrophenyl group and 4-cyano. Phenyl group, 3-trifluoromethylphenyl group, 3,4-dimethoxyphenyl group, 3,4-methylenedioxyphenyl group, 2,3,4,5,6-pentafluorophenyl group, 4-methylfuryl group, etc. Can be mentioned.

Further, in R 4 ^- R ^9, "acyl group which has ~ 1 carbon atoms which may 10 have a substituent" may be employed for example the following acyl groups. An aliphatic acyl group such as a formyl group, an acetyl group, a propionyl group, a 2-methylpropionyl group, a 2,2-dimethylpropionyl group and a 2-ethylhexanoyl group; a benzoyl group, a 1-naphthylcarbonyl group and a 2-naphthylcarbonyl group. , 2-Aromatic acyl groups such as frill carbonyl groups.

The number of carbon atoms of the acyl group is preferably 4 or less, and more preferably 2 or less. When the number of carbon atoms of the acyl group is within this range, steric hindrance between the fluorene rings is unlikely to occur, and the desired optical properties derived from the fluorene ring tend to be obtained.

As the substituent that the acyl group may have, the substituents exemplified below can be adopted, but substituents other than these may be adopted. Halogen atom selected from fluorine atom, chlorine atom, bromine atom and iodine atom; alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group and isopropyl group; Alkoxy group; acylamino group having 1 to 10 carbon atoms such as acetamide group and benzoylamide group; nitro group; cyano group; acyl group having 1 to 10 carbon atoms such as the halogen atom, the alkoxy group, the acetyl group and the benzoyl group. An aryl group having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group, wherein 1 to 3 hydrogen atoms may be substituted with the acylamino group, the nitro group, the cyano group and the like.

The number of the substituents is not particularly limited, but is preferably 1 to 3. When there are two or more substituents, the types of substituents may be the same or different. Further, from the viewpoint of industrially inexpensive production, it is preferable that ^{R 4} to R ^{9 are unsubstituted.}

Specific examples of the acyl group include chloroacetyl group, trifluoroacetyl group, methoxyacetyl group, phenoxyacetyl group, 4-methoxybenzoyl group, 4-nitrobenzoyl group, 4-cyanobenzoyl group and 4-trifluoromethylben. Soil groups and the like can be mentioned.

Further, in R ⁴ to R ⁹ , for example, the following alkoxy group and aryloxy group can be adopted as the "alkoxy group or aryloxy group having 1 to 10 carbon atoms which may have a substituent". .. Alkoxy groups such as methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, trifluoromethoxy group and phenoxy group.

The number of carbon atoms of the alkoxy group and the aryloxy group is preferably 4 or less, and more preferably 2 or less. When the carbon number of the alkoxy group and the aryloxy group is within this range, steric hindrance between the fluorene rings is unlikely to occur, and the desired optical properties derived from the fluorene ring tend to be obtained.

As the substituents that the alkoxy group and the aryloxy group may have, the substituents exemplified below can be adopted, but substituents other than these may be adopted. Halogen atom selected from fluorine atom, chlorine atom, bromine atom and iodine atom; alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group and isopropyl group; Alkoxy group; acylamino group having 1 to 10 carbon atoms such as acetamide group and benzoylamide group; nitro group; cyano group; acyl group having 1 to 10 carbon atoms such as the halogen atom, the alkoxy group, the acetyl group and the benzoyl group. An aryl group having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group, wherein 1 to 3 hydrogen atoms may be substituted with the acylamino group, the nitro group, the cyano group and the like.

Specific examples of the alkoxy group and the aryloxy group include chloromethyl group, bromomethyl group, 2-bromoethyl group, trifluoromethyl group, methoxymethyl group, methoxyethoxymethyl group, 3-chlorophenoxy group and 3-bromophenoxy. Examples thereof include a group, a 4-chlorophenoxy group, a 3-chlorophenoxy group, a 4-chlorophenoxy group, a 3-bromophenoxy group, a 4-bromophenoxy group, a 4-methoxyphenoxy group and the like.

Further, in R ⁴ to R ⁹ , for example, the following acyloxy groups can be adopted as the "acyloxy group having 1 to 10 carbon atoms which may have a substituent". An aliphatic acyloxy group such as a formyloxy group, an acetyloxy group, a propanoyloxy group, a butanoyloxy group, an acrylyloxy group and a methylenedioxy group; an aromatic acyloxy group such as a benzoyloxy group.

The number of carbon atoms of the acyloxy group is preferably 4 or less, and more preferably 2 or less. When the number of carbon atoms of the acyloxy group is within this range, steric hindrance between the fluorene rings is unlikely to occur, and the desired optical properties derived from the fluorene ring tend to be obtained.

As the substituent that the acyloxy group may have, the substituents exemplified below can be adopted, but substituents other than these may be adopted. Halogen atom selected from fluorine atom, chlorine atom, bromine atom and iodine atom; alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group and isopropyl group; Alkoxy group; acylamino group having 1 to 10 carbon atoms such as acetamide group and benzoylamide group; nitro group; cyano group; acyl group having 1 to 10 carbon atoms such as the halogen atom, the alkoxy group, the acetyl group and the benzoyl group. An aryl group having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group, wherein 1 to 3 hydrogen atoms may be substituted with the acylamino group, the nitro group, the cyano group and the like.

Specific examples of the acyloxy group include a chloroacetyloxy group, a trifluoroacetyloxy group, a methoxyacetyloxy group, a phenoxyacetyloxy group, a 4-methoxybenzoyloxy group, a 4-nitrobenzoyloxy group, and a 4-cyanobenzoyloxy group. , 4-Trifluoromethylbenzyloxy group and the like.

Further, in R ⁴ to R ⁹ , for example, the following amino groups can be adopted as the specific structure of the "amino group which may have a substituent", but other amino groups are adopted. It is also possible to do. Amino group; N-methylamino group, N, N-dimethylamino group, N-ethylamino group, N, N-diethylamino group, N, N-methylethylamino group, N-propylamino group, N, N-di An aliphatic amino group such as a propylamino group, an N-isopropylamino group, an N, N-diisopropylamino group; an aromatic amino group such as an N-phenylamino group, an N, N-diphenylamino group; a formamide group, an acetamide group, Acylamino groups such as decanoylamide group, benzoylamide group and chloroacetamide group; alkoxycarbonylamino group such as benzyloxycarbonylamino group and tert-butyloxycarbonylamino group.

The amino group is an N, N-dimethylamino group, an N-ethylamino group, or an N, N-diethylamino group, which does not have a highly acidic proton, has a small molecular weight, and tends to increase the fluorene ratio. It is preferable to adopt a group, and it is more preferable to adopt an N, N-dimethylamino group.

Further, in R ⁴ to R ⁹ , for example, the following vinyl group and ethynyl group can be adopted as the "vinyl group or ethynyl group having 1 to 10 carbon atoms which may have a substituent". It is also possible to adopt a vinyl group or the like other than these. Vinyl group, 2-methylvinyl group, 2,2-dimethylvinyl group, 2-phenylvinyl group, 2-acetylvinyl group, ethynyl group, methylethynyl group, tert-butylethynyl group, phenylethynyl group, acetylethynyl group, Trimethylsilylethynyl group.

The carbon number of the vinyl group and the ethynyl group is preferably 4 or less. When the carbon number of the vinyl group and the ethynyl group is within this range, steric hindrance between the fluorene rings is unlikely to occur, and the desired optical properties derived from the fluorene ring tend to be obtained. In addition, the longer the conjugated system of the fluorene ring makes it easier to obtain stronger inverse wavelength dispersibility.

Further, ^{as the "sulfur atom having a substituent" in R 4} to R ⁹ , for example, the following sulfur-containing groups can be adopted, but sulfur-containing groups other than these can also be adopted. Sulfonyl group; Alkylsulfonyl group such as methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, isopropylsulfonyl group; arylsulfonyl group such as phenylsulfonyl group, p-tolylsulfonyl group; methylsulfinyl group, ethylsulfinyl group, propylsulfinyl group Alkylsulfinyl groups such as isopropylsulfinyl group; arylsulfinyl groups such as phenylsulfinyl group and p-tolylsulfonyl group; alkylthio groups such as methylthio group and ethylthio group; arylthio groups such as phenylthio group and p-tolylthio group; methoxysulfonyl group , Ekoxysulfonyl groups such as ethoxysulfonyl groups; aryloxysulfonyl groups such as phenoxysulfonyl groups; aminosulfonyl groups; N-methylaminosulfonyl groups, N-ethylaminosulfonyl groups, N-tert-butylaminosulfonyl groups, N, N -Alkyl sulfonyl groups such as dimethylaminosulfonyl groups and N, N-diethylaminosulfonyl groups; arylaminosulfonyl groups such as N-phenylaminosulfonyl groups and N, N-diphenylaminosulfonyl groups. The sulfo group may form a salt with lithium, sodium, potassium, magnesium, ammonium or the like.

Among the sulfur-containing groups, it is preferable to use a methylsulfinyl group, an ethylsulfinyl group, or a phenylsulfinyl group, which does not have a highly acidic proton, has a small molecular weight, and can increase the fluorene ratio, and is preferably a methylsulfinyl group. It is more preferable to adopt.

Further, in R ⁴ to R ⁹ , for example, the following silyl group can be adopted as the "silicon atom having a substituent". Trialkylsilyl group such as trimethylsilyl group and triethylsilyl group; trialkoxysilyl group such as trimethoxysilyl group and triethoxysilyl group. Among these, a trialkylsilyl group that can be handled stably is preferable.

Further, in R ⁴ to R ⁹ , a fluorine atom, a chlorine atom, a bromine atom and an iodine atom can be adopted as the "halogen atom". Among these, it is preferable to use a fluorine atom, a chlorine atom, or a bromine atom, which is relatively easy to introduce and has a tendency to increase the reactivity at the 9-position of fluorene because of its electron-withdrawing property, and chlorine. It is more preferable to adopt an atom or a bromine atom.

Examples of the structural unit derived from the isosorbide-based dihydroxy compound include structural units represented by the following formulas.

Examples of the dihydroxy compound into which the structural unit represented by the general formula (3) can be introduced include isosorbide (ISB), isomannide, and isoidet having a stereoisomer relationship. These may be used individually by 1 type and may be used in combination of 2 or more type. Among these, ISB is most preferable from the viewpoint of availability and polymerization reactivity.

The structural unit represented by the general formula (3) is preferably contained in the resin in an amount of 5% by mass or more and 70% by mass or less, and preferably 10% by mass or more and 65% by mass or less. It is more preferable, and it is particularly preferable that the content is 20% by mass or more and 60% by mass or less. If the content of the structural unit represented by the general formula (3) is too small, the heat resistance may be insufficient. On the other hand, if the content of the structural unit represented by the general formula (3) is too large, the heat resistance becomes excessively high, and the mechanical properties and / or the melt processability deteriorate.

Examples of the structural unit derived from di, bird or polyethylene glycol include structural units represented by the following general formulas (4) to (8) that do not contain an aromatic component.

In the general formula (4), R ¹⁰ represents an alkylene group having 2 to 20 carbon atoms which may have a substituent.

As the dihydroxy compound into which the structural unit of the general formula (4) can be introduced, for example, the following dihydroxy compound can be adopted. Ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexane Dihydroxy compounds of linear aliphatic hydrocarbons such as diol, 1,9-nonanediol, 1,10-decanediol and 1,12-dodecanediol; dihydroxy of branched aliphatic hydrocarbons such as neopentyl glycol and hexylene glycol. Compound.

In the general formula (5), R ¹¹ represents a cycloalkylene group having 4 to 20 carbon atoms which may have a substituent.

As the dihydroxy compound into which the structural unit of the general formula (5) can be introduced, for example, the following dihydroxy compound can be adopted. Fats exemplified by 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantandiol, hydrogenated bisphenol A, 2,2,4,4-tetramethyl-1,3-cyclobutanediol and the like. A dihydroxy compound which is a secondary alcohol and a tertiary alcohol of a cyclic hydrocarbon.

In the general formula (6), R ¹² represents a cycloalkylene group having 4 to 20 carbon atoms which may have a substituent.

As the dihydroxy compound into which the structural unit of the general formula (6) can be introduced, for example, the following dihydroxy compound can be adopted. 1,2-Cyclohexanedimethanol, 1,3-Cyclohexanedimethanol, 1,4-Cyclohexanedimethanol, Tricyclodecanedimethanol, Pentacyclopentadecanedimethanol, 2,6-decalindimethanol, 1,5-decalingi It is exemplified by dihydroxy compounds derived from terpene compounds such as methanol, 2,3-decalindimethanol, 2,3-norbornandimethanol, 2,5-norbornandimethanol, 1,3-adamantandimethanol, limonene and the like. A dihydroxy compound that is a primary alcohol of alicyclic hydrocarbon.

In the general formula (7), R ¹³ represents an alkylene group having 2 to 10 carbon atoms which may have a substituent, and p is an integer of 1 to 40. Two or more R ^13s may be the same or different from each other.

As the dihydroxy compound into which the structural unit of the general formula (7) can be introduced, for example, the following dihydroxy compound can be adopted. Oxyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol and polypropylene glycol.

In the general formula (8), R ¹⁴ represents a group having an acetal ring having 2 to 20 carbon atoms which may have a substituent.

As the dihydroxy compound into which the structural unit of the general formula (8) can be introduced, for example, spiroglycol represented by the following structural formula (14), dioxane glycol represented by the following structural formula (15), or the like is adopted. Can be done.

Details of the polycarbonate resin are described in, for example, JP-A-2015-212816, JP-A-2010-134232 and JP-A-2020-064298. The description of the patent document is incorporated herein by reference.

A-2. First Hardened Layer and Second Hardened Layer The first hardened layer and the second hardened layer can be formed by cross-linking the resin contained in the retardation layer and a cross-linking agent as described above. Therefore, the first cured layer and the second cured layer may be substantially composed of the above resin crosslinked via a crosslinking agent. The retardation film according to the embodiment of the present invention has a first cured layer and a second cured layer on both sides of the retardation layer, so that the retardation change is small under a heating environment, a humidifying environment, and after contact with a solvent. Further, it has the advantage of being excellent in solvent resistance.

Examples of the cross-linking agent include tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,9-nonanediol di (meth) acrylate. 1,10-decanediol di (meth) acrylate, 2-ethyl-2-butylpropanediol di (meth) acrylate, bisphenol A di (meth) acrylate, bisphenol A ethylene oxide adduct di (meth) acrylate, bisphenol A propylene Oxide adduct Di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, neopentyl glycol di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, dioxane glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimetylolprophantri (meth) acrylate, pentaerythritol tri (meth) acrylate , Pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, EO-modified diglycerin tetra (meth) acrylate and other (meth) acrylic acids and esters of polyhydric alcohols. Examples include the compound, 9,9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl] fluorene. These can be used alone or as a mixture of two or more. Among these, tricyclodecanedimethanol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and 1,6-hexanediol di (meth) acrylate are particularly preferable. The cross-linking agent can be appropriately selected depending on the swelling property of the stretched resin film to be cross-linked.

The thickness of the first cured layer and the second cured layer is preferably 0.2 μm to 10.0 μm, and more preferably 0.5 μm to 5.0 μm. By having the thickness of the first cured layer and the second cured layer in such a range, a desired gel fraction can be obtained, and as a result, the phase difference changes under the heating environment, the humidifying environment and after the solvent contact. It is possible to obtain a retardation film having a small size and excellent solvent resistance.

B. Method for manufacturing a retardation film B-1. Method for Producing Resin Film Any suitable method can be adopted as the method for forming the resin film. For example, a melt extrusion method (for example, T die molding method), a cast coating method (for example, a casting method), a calendar molding method, a hot pressing method, a coextrusion method, a comelt method, a multi-layer extrusion, an inflation forming method and the like can be mentioned. Will be. Preferably, a T-die molding method, a casting method and an inflation molding method are used.

The thickness of the resin film (that is, the unstretched film) can be set to an arbitrary appropriate value according to desired optical characteristics, stretching conditions described later, and the like. It is preferably 50 μm to 300 μm, and more preferably 80 μm to 250 μm.

B-2. Method for Producing Stretched Resin Film For the stretching, any appropriate stretching direction and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) can be adopted as long as the above stretched resin film can be obtained. Specifically, various stretching methods such as free-end stretching, fixed-end stretching / free-end shrinkage, and fixed-end shrinkage can be used alone or simultaneously or sequentially. The stretching direction can also be performed in various directions and / or dimensions such as a horizontal direction, a vertical direction, a thickness direction, and a diagonal direction. The stretching temperature is preferably in the range of the glass transition temperature (Tg) ± 20 ° C. of the resin film.

By appropriately selecting the stretching method and stretching conditions, a retardation film having desired optical characteristics (for example, in-plane retardation) can be finally obtained.

In one embodiment, the stretched resin film is produced by uniaxially stretching or fixed-end uniaxially stretching the resin film. Specific examples of the uniaxial stretching include a method of stretching the resin film in the longitudinal direction (that is, the longitudinal direction) while running the resin film in the long direction. The draw ratio is preferably 10% to 500%.

In another embodiment, the stretched resin film is produced by continuously diagonally stretching a long resin film in a direction of an angle θ with respect to the long direction. By adopting diagonal stretching, a long stretched resin film having an orientation angle of an angle θ with respect to the long direction of the film can be obtained. The process can be simplified.

Examples of the stretching machine used for diagonal stretching include a tenter type stretching machine capable of applying a feeding force, a pulling force, or a pulling force at different speeds in the lateral and / or vertical directions. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as the long resin film can be continuously and diagonally stretched.

Examples of the method of diagonal stretching include JP-A-50-83482, JP-A-2-113920, JP-A-3-182701, JP-A-2000-9912, and JP-A-2002-86554. Examples thereof include the methods described in JP-A-2002-22944.

The thickness of the stretched resin film is preferably 10 μm to 90 μm, more preferably 20 μm to 50 μm.

As the stretched resin film, a commercially available film may be used as it is, or a commercially available film may be used by secondary processing (for example, stretching treatment, surface treatment) depending on the purpose. Specific examples of commercially available films include the trade name "Pure Ace RM" manufactured by Teijin Limited.

In one embodiment, the stretched resin film is subjected to a relaxation treatment. This makes it possible to relieve the stress caused by stretching. Any appropriate conditions may be adopted as the mitigation processing conditions. For example, the stretched resin film is shrunk along the stretching direction at a predetermined relaxation temperature and a predetermined relaxation rate (that is, shrinkage rate). The relaxation temperature is preferably 60 ° C to 150 ° C. The relaxation rate is preferably 3% to 6%.

B-3. Post-crosslinking (formation of first hardened layer and second hardened layer)
In one embodiment, a polyethylene terephthalate (PET) film is roll-laminated on both sides of the stretched resin film via a reactive composition containing a cross-linking agent and a radical generator. By performing a crosslinking reaction on the obtained laminate, a first cured layer and a second cured layer can be formed. In another embodiment, the surface of the stretched resin film is coated with a reactive composition containing a cross-linking agent, a radical generator (with a diluting solvent if necessary), and then heat-treated as necessary. A cured layer can be obtained by carrying out a cross-linking reaction (by heat or UV irradiation) in a nitrogen atmosphere. By applying this operation to both sides of the stretched resin film, a first cured layer and a second cured layer can be formed on the surface of the stretched resin film (phase difference layer). In the formation of such a first cured layer and the second cured layer, the resin forming the stretched resin film does not need to contain a crosslinkable group. When a stretched resin film is manufactured using a resin containing a crosslinkable group, problems such as gelation of the resin may occur in the manufacturing process (for example, kneading, extrusion, stretching). According to the embodiment of the present invention, it is possible to manufacture a retardation film having a first cured layer and a second cured layer without causing such a problem. Further, according to the post-crosslinking according to the embodiment of the present invention, the retardation film can be produced according to the embodiment of the present invention without modifying the normal retardation film and the process for producing the retardation film. .. In this respect, the invention of the present application has an excellent effect.

When the reactive composition is applied to the surface of the stretched resin film as in another embodiment described above, heat treatment may be performed in order to promote the penetration of the cross-linking agent into the stretched resin film. The heating temperature of the heat treatment is preferably lower than the glass transition temperature of the resin of the stretched resin film. This is because the phase difference of the stretched resin film decreases when the heat treatment is performed at a temperature higher than the glass transition temperature. The heat treatment is unnecessary when a cross-linking agent having high permeability to the stretched resin film is used. When the reactive composition contains a volatile solvent, the heat treatment can be performed in combination with the drying step.

Typical examples of the radical generator include a thermal radical generator and a photoradical generator, both of which can be used. Further, the radical generator includes a cleavage type radical generator and a hydrogen abstraction type radical generator, and an agent having a high hydrogen abstraction ability such as a hydrogen abstraction type radical generator is preferably used. That is, in the embodiment of the present invention, a hydrogen abstraction type thermal radical generator or a hydrogen abstraction type photoradical generator can be preferably used. When the hydrogen abstraction type radical generator becomes a radical, the radical abstracts hydrogen in the resin contained in the retardation film, generates a radical in the chemical structure of the resin, and the monomer polymerizes (that is, that is, starts from there. Addition) It is considered to react. This is because in the embodiment of the present invention, since the polyfunctional monomer is used as the cross-linking agent, the reaction point thereof becomes the cross-linking point.

Examples of the hydrogen abstraction type thermal radical generator include organic peroxides such as perbutyl D, perbutyl C, park mill D, perhexyl D, perbutyl E, perbutyl I, perhexyl I, perbutyl Z, perhexyl Z, perbutyl A, and perbutyl 355. , Perbutyl L, Perbutyl O, Perhexyl O, Perocta O, Perbutyl PV, Perhexyl PV, Perbutyl ND, Perhexyl ND, Perocta ND, Perhexa V, Perhexa 22, Perhexa 3M, Perhexa C, Perhexa HC, Pertetra A, Perhexa MC, Niper Examples include BW, pearloyle 355, and pearloyle L. Examples of the hydrogen abstraction type photoradical generator include those described in JP-A-2012-52000. Further, 3,3', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone (BTTB), perdual TA, and perdual TX can also be mentioned.

The retardation film obtained above can be subjected to matrix-assisted laser desorption / ionization time-of-flight mass spectrometer (MALDI-TOFMS, manufactured by BRUKER DALTONICS) after high-temperature methanol decomposition treatment. Whether or not the post-crosslinking reaction has proceeded can be evaluated depending on whether or not a repeating pattern derived from the crosslinking reaction is obtained.

C. Circular polarizing plate The circularly polarizing plate according to the embodiment of the present invention includes the retardation film according to the above items A and B, and a polarizing element. A protective layer may be placed on at least one side of the polarizing element. The angle formed by the slow axis of the retardation layer of the retardation film and the absorption axis of the polarizing element is preferably 35 ° to 55 °, more preferably 40 ° to 50 °, and particularly preferably 43 to 47 °. °, most preferably about 45 °.

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

Specific examples of the polarizing element 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-based partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine or a bicolor dye, a polyene-based oriented film such as a dehydrated product of PVA or a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical properties, a polarizing element obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film 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. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Further, it may be dyed after being stretched. If necessary, the PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a cleaning 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 stain and / or the blocking inhibitor on the surface of the PVA-based film, but also to swell the PVA-based film to cause uneven dyeing. Etc. can be prevented.

Specific examples of the polarizing element 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 polarizing element obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizing element obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying it. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer a stator. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further comprise, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. The obtained resin base material / polarizing element laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizing element), and the resin base material is peeled off from the resin base material / polarizing element laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface and used. Details of the method for producing such a polarizing element are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The entire description of the publication is incorporated herein by reference.

The thickness of the polarizing element is, for example, 1 μm to 80 μm. In one embodiment, the thickness of the polarizing element is preferably 1 μm to 15 μm, more preferably 3 μm to 10 μm, and even more preferably 3 μm to 8 μm. When the thickness of the polarizing element is within such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

D. Image display device The retardation film according to items A and B and the circularly polarizing plate according to item C can be used for an image display device. Therefore, in the embodiment of the present invention, an image display device using such an optical laminate is also included. Typical examples of the image display device include a liquid crystal display device and an organic EL display device. The image display device according to the embodiment of the present invention includes the retardation film according to the above items A and B and the circularly polarizing plate according to the item C.

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 of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.

(1) Thickness Measured using a dial gauge (manufactured by PEACOCK, product name "DG-205 type pds-2").
(2) Phase difference value A sample having a size of 50 mm × 50 mm was cut out from the retardation films obtained in Examples and Comparative Examples to prepare a measurement sample, and the measurement was performed using Axoscan manufactured by Axometrics. The measurement wavelengths were 450 nm, 550 nm and 650 nm, and the measurement temperature was 23 ° C.
(3) Heat phase difference change A sample is prepared by laminating the retardation film obtained in Examples and Comparative Examples to glass via an adhesive layer, and the phase difference is measured by the same method as the phase difference measurement. Was measured. After putting the measured sample into an oven at 105 ° C. for 120 hours, the sample was taken out, the phase difference was measured again, and the rate of change of Re (550) was determined.
(4) Humidification phase difference change A sample is prepared by laminating the retardation film obtained in Examples and Comparative Examples to glass via an adhesive layer, and the phase difference is measured by the same method as the phase difference measurement. Was measured. The measured sample was placed in an oven at 85 ° C. and a humidity of 85% for 120 hours, the sample was taken out, the phase difference was measured again, and the rate of change (%) of Re (550) was determined.
(5) Change in phase difference after contact with solvent With respect to the retardation films obtained in Examples and Comparative Examples, the phase difference was measured by the same method as in the measurement of the phase difference. Toluene or cyclopentanone was added dropwise to the sample after measurement, and the solvent was wiped off after 1 minute. After wiping off the solvent, the phase difference at the point where the solvent came into contact was measured again, and the rate of change (%) of Re (550) was determined.
(6) Solvent resistance test Toluene or cyclopentanone was added dropwise to the retardation films obtained in Examples and Comparative Examples, and the solvent was wiped off after 1 minute. After wiping off the solvent, the one in which no trace was left in the place where the solvent came into contact was regarded as good, and the one in which the trace remained was regarded as defective.
(7) Gel fraction The retardation films obtained in Examples and Comparative Examples were collected at about 5 cm square, weighed, and then immersed in 50 g of toluene for 1 hour. After soaking, the residue was taken out and dried at 150 ° C. for 10 minutes, the weight was measured again, and the gel fraction (%) was calculated.

[Example 1]
1. 1. Preparation of Polycarbonate Resin Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100 ° C. Bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] methane 29.60 parts by mass (0.046 mol), ISB 29.21 parts by mass (0.200 mol), SPG 42.28 parts by mass (0.139 mol) , DPC 63.77 parts by mass (0.298 mol) and calcium acetate monohydrate 1.19 × 10-2 parts by mass (6.78 × 10-5 mol) were charged as a catalyst. After substituting nitrogen under reduced pressure in the reactor, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100 ° C. The internal temperature was brought to 220 ° C. 40 minutes after the start of the temperature rise, and the depressurization was started at the same time as controlling to maintain this temperature, and the temperature was 13.3 kPa 90 minutes after reaching 220 ° C. 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 non-condensed phenol vapor was guided to a condenser at 45 ° C. for recovery. Nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and depressurization in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Then, the polymerization was allowed to proceed until the stirring power became a predetermined value. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, the produced polyester carbonate was extruded into water, and the strands were cut to obtain pellets.

2. 2. Preparation of resin film 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 200 mm, set temperature: 250 ° C). ), A chill roll (set temperature: 120 to 130 ° C.), and a film-forming device equipped with a winder were used to prepare a resin film having a thickness of 135 μm.

3. 3. Preparation of Stretched Resin Film The obtained long resin film was stretched in the width direction at a stretching temperature of 134 ° C. and a stretching ratio of 2.8 times, and subsequently subjected to relaxation treatment in the width direction of the stretched film. did. The conditions for the relaxation treatment were a relaxation temperature of 130 ° C. and a relaxation rate of 4.5%. Then, it was heat-treated at 125 ° C. for 2 minutes to obtain a stretched resin film having a thickness of 48 μm. The obtained stretched resin film had Re (550) of 180 nm and Re (450) / Re (550) of 0.85.

4. Post-crosslinking Crosslinks with 10 parts by mass of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by Nichiyu Co., Ltd., product name "Perocta O"), which is a hydrogen abstraction type thermal radical generator. A reactive composition 1 was prepared by mixing with 100 parts by mass of a tricyclodecanedimethanol diacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., product name “A-DCP”) as an agent. 3. A polyethylene terephthalate (PET) film (thickness 50 μm) was roll-laminated on both sides of the stretched resin film obtained in 1 above via the reactive composition 1, and “PET film / reactive composition 1 / stretched resin film / reaction” was obtained. A laminate having the composition of "sexual composition 1 / PET film" was obtained. The laminate was heat-treated at 120 ° C. for 10 minutes to carry out a crosslinking treatment. Next, the PET films on both sides of the laminated body were peeled off to obtain a retardation film. The obtained retardation film had a thickness of 50 μm, a Re (550) of 144 nm, a Re (450) / Re (550) of 0.85, and a haze of 0.7%. The obtained retardation film was subjected to the evaluations (3) to (7) above. The results are shown in Table 1.

5. Evaluation of post-crosslinking 4. The retardation film obtained in 1 was subjected to high temperature methanol decomposition treatment, and MALDI-TOFMS measurement was performed on the decomposed methyl ester product. As a result, isosorbide (ISB) + PMA was added in addition to methyl acrylate (PMA) alone. The existence of the body was confirmed. In the ISB + PMA adduct, the Na adduct of the oligomer obtained by adding methyl acrylate to isosorbide was detected as a peak group represented by m / z = 146.0579 (ISB) +86.0348 (PMA) × n + 22.99. I was certified by being there. Elemental substance PMA not bound to isosorbide was identified by the fact that the Na adduct of the oligomer of methyl acrylate was detected as a peak group represented by m / z = 0 + 86.0348 (PMA) × n + 22.99. ..

(ISB + PMA prism): Estimated binding position

(PMA alone)
The presence of the ISB + PMA adduct means that a polyfunctional acrylic monomer was formed into a carbon-carbon bond in the polyester carbonate resin.

[Example 2]
A stretched resin film was obtained in the same manner as in Example 1 except that the stretching temperature and the stretching ratio were appropriately adjusted. The stretched resin film had a thickness of 48 μm, a Re (550) of 147 nm, and a Re (450) / Re (550) of 0.85.

1 part by mass of 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name "DETX-S"), which is a hydrogen abstraction type photoradical generator, and 1,6-hexanediol diacrylate (Shin Nakamura), which is a cross-linking agent. 50 parts by mass of trimethylolpropane triacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name "A-TMPT") and 50 parts by mass of trimethylolpropane triacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name "A-TMPT") are mixed and reactive. Composition 2 was prepared. A polyethylene terephthalate (PET) film (thickness 50 μm) was roll-laminated on both sides of the stretched resin film via the reactive composition 2, and “PET film / reactive composition 2 / stretched resin film / reactive composition” was obtained. A laminate having the composition of "2 / PET film" was obtained. The laminate was subjected to UV irradiation (900 mJ / cm ² ) for cross-linking treatment. Next, the PET films on both sides of the laminated body were peeled off to obtain a retardation film. The obtained retardation film had a thickness of 50 μm, a Re (550) of 144 nm, a Re (450) / Re (550) of 0.85, and a haze of 0.9%. The obtained retardation film was subjected to the evaluations (3) to (7) above. The results are shown in Table 1.

[Example 3]
A stretched resin film was obtained in the same manner as in Example 1 except that the stretching temperature and the stretching ratio were appropriately adjusted. The stretched resin film had a thickness of 48 μm, a Re (550) of 165 nm, and a Re (450) / Re (550) of 0.85.

3,3', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone (manufactured by Nichiyu Co., Ltd., product name "BTTB-20G" (PGMEA solution 20% by weight solution)), which is a hydrogen abstraction type photoradical generator. 10 parts by weight, 50 parts by weight of 1,6-hexanediol diacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name "A-HD-N") and trimethylolpropane triacrylate (Shin Nakamura Chemical Industry Co., Ltd.) The reactive composition 3 was prepared by mixing with 50 parts by mass (manufactured by the company, product name "A-TMPT"). The reactive composition 3 was bar-coated on one side surface of the stretched resin film, heat-treated at 50 ° C. for 10 minutes, and then UV-irradiated (900 mJ / cm ² ) in a nitrogen atmosphere for cross-linking treatment. .. Similarly, the reactive composition 3 is bar-coated on another surface, heat-treated at 50 ° C. for 10 minutes, and then UV-irradiated (900 mJ / cm ² ) in a nitrogen atmosphere for cross-linking treatment. As a result, a retardation film was obtained. The obtained retardation film had a thickness of 55 μm, a Re (550) of 144 nm, a Re (450) / Re (550) of 0.85, and a haze of 0.7%. The obtained retardation film was subjected to the evaluations (3) to (7) above. The results are shown in Table 1.

[Comparative Example 1]
A retardation film was obtained in the same manner as in Example 1 except that the stretching temperature and the stretching ratio were appropriately adjusted and the crosslinking treatment using the reactive composition was not performed as in Examples 1 and 2. The retardation film had a thickness of 48 μm, a Re (550) of 144 nm, a Re (450) / Re (550) of 0.85, and a haze of 0.3%. The obtained retardation film was subjected to the evaluations (3) to (7) above. The results are shown in Table 1.

As is clear from Table 1, according to the retardation film of the embodiment of the present invention, it can be seen that the retardation change after the heating test, the humidification test and the solvent contact is small, and the solvent resistance is also excellent.

The retardation film according to the embodiment of the present invention is suitably applied to a circularly polarizing plate and an image display device.

10 First cured layer 20 Phase difference layer 30 Second cured layer 100 Phase difference film

Claims

A first cured layer, a retardation layer, and a second cured layer are provided in this order.
The retardation layer is formed of a stretched resin film, and the retardation layer is formed of a stretched resin film.
The stretched resin film contains a resin containing at least one binding group selected from carbonate and ester bonds.
In the first cured layer and the second cured layer, the cross-linking agent having a carbon-carbon double bond and the resin are cross-linked via the carbon-carbon double bond.
Phase difference film.
The retardation film according to claim 1, wherein the resin contains a structural unit represented by the following formula.
The retardation film according to claim 1 or 2, wherein the resin contains a structural unit represented by the following formula.
The retardation film according to any one of claims 1 to 3, which satisfies the relationship of Re (450) <Re (550) <Re (650).
The retardation film according to any one of claims 1 to 4, which satisfies the relationship of 0.7 <Re (450) / Re (550) <1.0.
The retardation film according to any one of claims 1 to 5, wherein Re (550) is 100 nm to 180 nm or 220 nm to 330 nm.
A circularly polarizing plate comprising the retardation film according to any one of claims 1 to 6 and a polarizing element.
An image display device comprising the retardation film according to any one of claims 1 to 6.
An image display device provided with the circularly polarizing plate according to claim 7.
The method for manufacturing a retardation film according to any one of claims 1 to 6.
A step of cross-linking the resin and the cross-linking agent via the carbon-carbon double bond of the cross-linking agent using a radical generator.
A method for manufacturing a retardation film.
The method for producing a retardation film according to claim 10, wherein the radical generator is a hydrogen abstraction type photoradical generator.
The method for producing a retardation film according to claim 10, wherein the radical generator is a hydrogen abstraction type thermal radical generator.