TW201942217A - Circularly polarizing plate - Google Patents

Abstract

The present invention provides a circularly polarizing plate which is capable of ensuring the adhesion between a polarizer and a retardation film, while being capable of maintaining excellent antireflection characteristics. A circularly polarizing plate according to the present invention is sequentially provided with a polarizer, a highly adhesive layer which contains a crosslinking agent and a urethane resin having a carboxyl group, and a retardation film which contains a polycarbonate resin and functions as a [lambda]/4 plate, in this order; and the refractive index difference between the retardation film and the highly adhesive layer is 0.01 or less.

Description

Circular polarizer

The invention relates to a circular polarizing plate.

In display devices such as liquid crystal display devices and organic EL (Electro-Luminescence) display devices, for the purpose of preventing reflection of external light, etc., a retardation film having a polarizing element and a retardation film functioning as a λ / 4 plate is used. Circular polarizer. In recent years, a retardation film using a polycarbonate resin has been proposed (Patent Document 1). However, the retardation film using a polycarbonate-based resin has room for improvement in adhesion with other layers such as a polarizing element.

In order to improve the adhesion of the film, it is proposed to form an easy-adhesion layer on one side of the film (Patent Document 2). However, when applied to a retardation film used in a circularly polarizing plate, there is a problem that the anti-reflection characteristics of the circularly polarizing plate cannot be fully exerted due to the formation of an easy-adhesion layer.
Prior art literature patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2015-212816 Patent Document 2: Japanese Patent Laid-Open Publication No. 2014-10292

[Problems to be solved by the invention]

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to provide a circularly polarizing plate which can ensure the adhesion between a polarizing element and a retardation film and maintain excellent anti-reflection characteristics.
[Technical means to solve the problem]

The circular polarizing plate of the present invention is sequentially provided with a polarizing element, an easy-adhesion layer containing a urethane resin having a carboxyl group and a crosslinking agent, and a retardation film containing a polycarbonate resin and functioning as a λ / 4 plate; and The refractive index difference between the retardation film and the easy-adhesion layer is 0.01 or less.
In one embodiment, the crosslinking agent is a compound having a methylol group or a compound having an oxazoline group.
In one embodiment, the thickness of the easy-adhesion layer is less than 1 μm.
In one embodiment, the retardation film satisfies the relationship of Re (450) <Re (550).
In one embodiment, a 90 ° adhesive force between the retardation film and the easy-adhesion layer is 1.0 N / 15 mm or more.
In one embodiment, a 90 ° adhesive force between the polarizing element and the easy-adhesion layer is 1.0 N / 15 mm or more.
In one embodiment, the 90 ° adhesive force between the polarizing element and the easy-adhesion layer after being left for 500 hours at 85 ° C. is 1.0 N / 15 mm or more.
In one embodiment, the 90 ° adhesive force between the polarizing element and the easy-adhesion layer after being left for 240 hours under the conditions of 60 ° C and 95% RH is 0.5 N / 15mm or more.
[Effect of the invention]

According to the present invention, the adhesion between the polarizing element and the retardation film can be sufficiently ensured. Furthermore, even after the endurance test is provided, it is possible to prevent the occurrence of defects such as cohesive failure of the primer, peeling of the interface, and polarization cracking. In addition, it is possible to maintain the excellent anti-reflection characteristics of the circularly polarizing plate. Furthermore, in the circular polarizing plate of the present invention, the flaws on the surface of the retardation film can be buried by the easy-adhesion layer. Therefore, the smoothness of the surface of the retardation film can also be maintained. In addition, the circularly polarizing plate of the present invention can exhibit anti-reflection characteristics better regardless of the type of surface treatment.

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

(Definition of terms and signs)
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 where the refractive index in the plane is the largest (that is, the direction of the late phase axis), and "ny" is the refractive index in the plane that is orthogonal to the late phase axis (that is, the direction of the phase axis) "Nz" is the refractive index in the thickness direction.
The "refractive index" of a film that causes birefringence after stretching is a value calculated from (nx + ny + nz) / 3 unless specifically stated otherwise.
(2) In-plane phase difference (Re)
"Re (550)" is an in-plane retardation of a film measured with light having a wavelength of 550 nm at 23 ° C. Re (550) is determined by the formula: Re = (nx-ny) × d when the thickness of the film is d (nm). In addition, "Re (450)" is an in-plane retardation of a film measured with light having a wavelength of 450 nm at 23 ° C.
(3) Phase difference in thickness direction (Rth)
"Rth (550)" is a phase difference in the thickness direction of the film measured with light having a wavelength of 550 nm at 23 ° C. Rth (550) is determined by the formula: Rth = (nx-nz) × d when the thickness of the film is d (nm). In addition, "Rth (450)" is a phase difference in the thickness direction of the film measured with light having a wavelength of 450 nm at 23 ° C.
(4) Nz coefficient
The Nz coefficient is obtained from Nz = Rth / Re.

A. Circular polarizing plate The circular polarizing plate of the present invention is sequentially provided with a polarizing element, an easy-adhesive layer containing a urethane resin having a carboxyl group and a crosslinking agent, and a phase containing a polycarbonate resin and functioning as a λ / 4 plate Poor film. Practically, an adhesive layer is formed between the easy-adhesion layer and the polarizing element. By forming the easy-adhesion layer as described above, the circular polarizing plate of the present invention can ensure sufficient adhesion between the polarizing element and the retardation film containing a polycarbonate resin. Furthermore, sufficient adhesion can be ensured even after the endurance test of heating and heating and humidification.

FIG. 1 is a schematic cross-sectional view of a circular polarizing plate according to an embodiment of the present invention. The circular polarizing plate 100 includes a polarizing element 10, an adhesive layer 40, an easy-adhesion layer 20, and a retardation film 30 in this order. In the circular polarizing plate 100 of the illustrated example, the polarizing element 10 and the retardation film 30 are laminated with an adhesive layer 40 interposed therebetween. That is, in the illustrated example, the polarizing element 10 and the retardation film 30 are laminated directly (without interposing another optical function layer). If necessary, the circular polarizing plate 100 may be laminated with a protective film (not shown) on the side of the polarizing element 10 opposite to the retardation film 30.

In the circular polarizing plate of the present invention, the refractive index difference between the retardation film and the easy-adhesion layer is 0.01 or less, and preferably 0.005 or less. Since the refractive index difference between the retardation film and the easy adhesion is 0.01 or less, the excellent anti-reflection characteristics of the circular polarizing plate can be maintained. The smaller the refractive index difference between the retardation film and the easy-adhesion layer, the better, particularly preferably, the refractive index difference between the retardation film and the easy-adhesion layer is 0 (the refractive index of the retardation film and the easy-adhesion layer is the same).

In the circular polarizing plate of the present invention, the 90 ° bonding force between the retardation film and the easy-adhesion layer is preferably 1.0 N / 15 mm or more, and more preferably 2.0 N / 15 mm or more. The 90 ° bonding force between the polarizing element and the easy-adhesion layer is preferably 1.0 N / 15 mm or more, and more preferably 2.0 N / 15 mm or more. As long as the 90 ° adhesive force between the retardation film and the easy-adhesion layer and the polarizing element and the easy-adhesion layer is within the above range, sufficient adhesion between the polarizing element and the retardation film can be ensured. In this specification, the 90 ° adhesive force can be measured by the method described in the examples.

In the circular polarizing plate of the present invention, the 90 ° adhesive force between the polarizing element and the easy-adhesive layer after being left for 500 hours at 85 ° C (hereinafter, also referred to as heating conditions) is preferably 1.0 N / 15mm or more. More preferably, it is 2.0 N / 15mm or more. The 90 ° adhesive force between the polarizing element and the easy-adhesive layer after being left for 240 hours under the conditions of 60 ° C and 95% RH (hereinafter also referred to as heating and humidifying conditions) is preferably 0.5 N / 15mm or more, more preferably It is 1.0 N / 15mm or more. Since the 90 ° adhesive force after being placed under heating and heating and humidifying conditions is within the above range, sufficient adhesion can be ensured even after the endurance test.

B. Polarizing Element As the polarizing element 10, any appropriate polarizing element can be used. For example, the resin film forming the polarizing element may be a single-layer resin film or a laminated body of two or more layers.

Specific examples of the polarizing element containing a single-layer resin film include a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene-vinyl acetate copolymer-based partially saponified film. The molecular film is subjected to a dyeing treatment and extension treatment using a dichroic substance such as iodine or a dichroic dye, a dehydration treatment product of PVA, or a polyene-based alignment film such as a dehydrochlorination treatment product of polyvinyl chloride. From the viewpoint of excellent optical characteristics, it is preferable to use a polarizing element obtained by dyeing a PVA-based film with iodine and uniaxially stretching it.

The above dyeing with iodine is performed, for example, by immersing a PVA-based film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after the dyeing treatment, or it can be extended while dyeing. It is also possible to perform dyeing after stretching. If necessary, the PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, and the like. For example, by immersing the PVA-based film in water and washing it before dyeing, not only the dirt or anti-caking agent on the surface of the PVA-based film can be cleaned, but also the PVA-based film can be swelled to prevent uneven dyeing.

Specific examples of the polarizing element obtained by using the laminate include a laminate using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and coating formed on A polarizing element obtained by laminating a PVA-based resin layer of the resin substrate. A polarizing element obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying it. A PVA-based resin layer is formed on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; the laminate is extended and dyed to use the PVA-based resin layer as a polarizing element. In this embodiment, stretching typically includes dipping and stretching a laminated body in a boric acid aqueous solution. Furthermore, if necessary, the stretching can further include stretching the laminate in the air at a high temperature (for example, 95 ° C. or higher) before stretching in an aqueous boric acid solution. The obtained laminate of the resin substrate / polarizing element can be used directly (that is, the resin substrate can be used as an inner protective layer provided between the retardation film and the polarizing element), or it can be used from the resin substrate / polarizing element. The laminated body peels off the resin base material (resin layer), and an appropriate protective layer is optionally used as the inner protective layer in the peeling area layer. The details of the method of manufacturing such a polarizer are described in, for example, Japanese Patent Laid-Open No. 2012-73580. The entire description of the publication is incorporated herein by reference.

The thickness of the polarizing element can be appropriately designed according to the purpose and application, and is preferably 3 μm to 25 μm.

The polarizing element preferably represents an absorption dichroism at an arbitrary wavelength of 380 nm to 780 nm. The single transmittance of the polarizing element is preferably 42.0% to 46.0%, and more preferably 43.0% to 46.0%. The degree of polarization of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

C. Easy-adhesion layer The easy-adhesion layer 20 contains a polyurethane resin having a carboxyl group and a crosslinking agent. The easy adhesion layer is formed on one surface of the retardation film. For example, a circularly polarizing plate is obtained by forming an adhesive layer on the surface of the retardation film on which the easy-adhesion layer is formed and bonding it to a polarizing element. The easy-adhesion layer contains a polyurethane resin having a carboxyl group and a cross-linking agent, thereby improving the adhesion between the polarizing element and the retardation film containing a polycarbonate resin. Furthermore, even when a circularly polarizing plate is provided in a durability test, this adhesiveness can be maintained. In the circular polarizing plate of the present invention, the refractive index difference between the retardation film and the easy-adhesion layer is 0.01 or less. Therefore, the excellent anti-reflection characteristics of the obtained circular polarizing plate can be maintained.

C-1. Polyurethane resin having a carboxyl group The above-mentioned polyurethane resin has a carboxyl group. By having a carboxyl group, it is possible to provide a circular polarizing plate having excellent adhesion between a polarizing element and a retardation film (especially at high temperatures). Polyurethane-based resins are typically obtained by reacting a polyol with a polyisocyanate. The polyol is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any appropriate polyol can be used. For example, polypropylene polyol, polyester polyol, polyether polyol, and the like. These can be used individually or in combination of 2 or more types.

The urethane resin having a carboxyl group is obtained, for example, by reacting a chain extender having a free carboxyl group in addition to the polyol and the polyisocyanate. Examples of the chain length agent having a free carboxyl group include dihydroxycarboxylic acid and dihydroxysuccinic acid. Examples of the dihydroxycarboxylic acid include dimethylolalkanoic acid (for example, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolvaleric acid) And so on. These can be used individually or in combination of 2 or more types.

In the production of the polyurethane resin, in addition to the above components, other polyols and other chain extenders may be reacted. Examples of other polyhydric alcohols include sorbitol, 1,2,3,6-hexatetraol, 1,4-sorbitan, 1,2,4-butanetriol, and 1,2,5-pentatriol. Polyols having three or more hydroxyl groups such as alcohol, glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, and the like. Examples of other chain extenders include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and neopentyl glycol. , Pentanediol, 1,6-hexanediol, 1,2-propylene glycol and other diols; ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine, aminoethylethanolamine and other fats Family diamines; alicyclic diamines such as isophorone diamine, 4,4'-dicyclohexanemethane diamine; aromatic diamines such as xylylene diamine and toluene diamine.

C-2. Cross-linking agent As the above-mentioned cross-linking agent, any appropriate cross-linking agent can be used. It is preferable to use a crosslinking agent capable of reacting with a carboxyl group and a crosslinking agent capable of reacting with a polyvinyl alcohol-based resin. Examples of the crosslinking agent capable of reacting with a carboxyl group include polymers having a group capable of reacting with a carboxyl group. Examples of the group capable of reacting with a carboxyl group include an organic amino group, an oxazoline group, an epoxy group, a carbodiimide group, an aldehyde group, and a methylol group. The crosslinking agent is preferably a polymer having an oxazoline group. The polymer having an oxazoline group has a long pot life at room temperature when mixed with the above-mentioned polyurethane resin, and the crosslinking reaction proceeds by heating, so the workability is good.

As the polymer, any appropriate polymer can be used. Examples include acrylic polymers, styrene-acrylic polymers, and the like. An acrylic polymer is preferable. By using an acrylic polymer, the adhesiveness between a polarizing element and a retardation film can be further improved.

The crosslinking agent capable of reacting with the polyvinyl alcohol resin is preferably a compound containing at least two functional groups having reactivity with the polyvinyl alcohol resin. For example, ethylene diamine, triethylene diamine, and hexamethylene diamine have two alkylene diamines and amine groups, respectively; toluene diisocyanate, hydrogenated toluene diisocyanate, and trimethylolpropane toluene diisocyanate Adducts, triphenylmethane triisocyanate, methylene bis (4-benzymethane triisocyanate), isophorone diisocyanate, and other ketooxime blocks or phenol blocks, etc. Glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerol or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl Epoxy such as aniline and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde; glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, maleicaldehyde, o-benzene Dialdehydes such as diformaldehyde; hydroxy groups such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylol melamine, ethylguanide, benzoguanamine and formaldehyde condensate- Formaldehyde resins; sodium, potassium, magnesium, calcium, aluminum, iron, nickel and other divalent metals, or salts of trivalent metals and their Oxide. The crosslinking agent capable of reacting with the PVA-based resin is preferably an amine-formaldehyde resin or a dialdehyde. The amino-formaldehyde resin is preferably a compound having a methylol group, and the dialdehyde is preferably glyoxal. A compound having a methylol group is preferable, and a methylol melamine is more preferable. By using a compound having a methylol group, a circularly polarizing plate having further excellent optical characteristics can be obtained.

The easy-adhesion layer is typically formed by applying a polyurethane resin having a carboxyl group and an easy-adhesion layer-forming composition containing a crosslinking agent to a retardation film. The content of the cross-linking agent of the easily-adhesive layer-forming composition can be set to any appropriate value. The content of the crosslinking agent is preferably 100 parts by weight with respect to the polyurethane resin having a carboxyl group, preferably 1 to 20 parts by weight, and more preferably 5 to 15 parts by weight. When the content of the cross-linking agent is in the above range, the adhesion between the polarizing element and the retardation film can be sufficiently ensured.

The easy-adhesive layer-forming composition can further contain any appropriate additives. Examples of the additives include anticaking agents, dispersion stabilizers, thixotropic agents, antioxidants, ultraviolet absorbers, defoamers, tackifiers, dispersants, surfactants, catalysts, fillers, lubricants, Antistatic agents.

The easily-adhesive layer 20 is typically formed by applying the easily-adhesive layer-forming composition to one surface of the retardation film 30 as described above and drying it. In the case of a retardation film-based stretched film, an unadhesive polycarbonate-based resin film may be formed after the easy-adhesive layer is formed, and it may also be formed from an extended polycarbonate-based resin film.

As a method for applying the easy-adhesive layer-forming composition, any appropriate method can be adopted. For example, die coating method, bar coating method, roll coating method, gravure coating method, rod coating method, slot coating method, curtain coating method, spray coating method, etc. . The drying temperature is typically 50 ° C or higher, preferably 70 ° C or higher, and more preferably 90 ° C or higher. By setting the drying temperature to such a range, it is possible to provide a circular polarizing plate having excellent discoloration resistance (particularly under high temperature and high humidity). The drying temperature is preferably 120 ° C or lower, and more preferably 100 ° C or lower.

The thickness of the easy-adhesion layer 20 can be set to any appropriate value. The thickness of the easy-adhesion layer 20 is preferably less than 1 μm, more preferably 50 nm to 500 nm, and still more preferably 200 nm to 400 nm. By setting it as such a range, the adhesiveness of a polarizing element and a retardation film can be ensured. Furthermore, when there is a flaw on the surface of the retardation film, the effect of filling the flaw can be exhibited.

D. Phase Difference Film The phase difference film 30 contains a polycarbonate resin and functions as a λ / 4 plate. In the retardation film containing a polycarbonate resin, there is a problem that the adhesion between the polarizing element and the retardation film cannot be sufficiently obtained. In the circular polarizing plate of the present invention, by forming the easy-adhesion layer on one side of the retardation film, and laminating a polarizing element on the surface on which the easy-adhesion layer is formed via an adhesive layer, a polarizer and a phase difference can be ensured. The tightness of the film.

The retardation film 30 typically has a late phase axis. In one embodiment, the angle θ formed by the retardation axis of the retardation film 30 and the absorption axis of the polarizing element 10 is preferably 38 ° to 52 °, more preferably 42 ° to 48 °, and even more preferably about 45 °. °. As long as the angle θ is within this range, a circularly polarizing plate having very excellent circularly polarizing characteristics can be obtained.

The retardation film preferably has a refractive index characteristic in a relationship of nx> ny ≧ nz. The retardation film is typically provided to impart anti-reflection characteristics to a circularly polarizing plate. In this case, the in-plane retardation Re (550) of the retardation film is preferably 80 nm to 200 nm, more preferably 100 nm to 180 nm, and still more preferably 110 nm to 170 nm. Moreover, "ny = nz" here includes not only the case where ny and nz are completely equal, but also the case where it is substantially equal. Therefore, as long as the effect of the present invention is not impaired, ny <nz may occur.

The birefringence Δn _{xy of the} retardation film is, for example, 0.0025 or more, and preferably 0.0028 or more. On the other hand, the upper limit of the birefringence Δn _{xy is} , for example, 0.0060, and preferably 0.0050. By optimizing the birefringence to such a range, it is possible to obtain a thin retardation film having desired optical characteristics.

The Nz coefficient of the retardation film is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and even more preferably 0.9 to 1.3. By satisfying such a relationship, when the obtained circular polarizing plate is used in an image display device, a very excellent reflection hue can be achieved.

The retardation film may indicate an inverse wavelength dispersion characteristic in which the retardation value becomes larger according to the wavelength of the measurement light, or a positive wavelength dispersion characteristic in which the retardation value becomes smaller according to the wavelength of the measurement light, or the retardation value may be obtained according to measurement The wavelength of light has almost no change in flat wavelength dispersion characteristics. The retardation film preferably exhibits inverse wavelength dispersion characteristics. In one embodiment, the retardation film has an inverse wavelength dispersion characteristic. In this case, the retardation film satisfies the relationship of Re (450) <Re (550), and the Re (450) / Re (550) of the retardation film is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. the following. With such a structure, very excellent anti-reflection characteristics can be achieved. In another embodiment, the retardation film has a flat wavelength dispersion characteristic. In this case, the Re (450) / Re (550) of the retardation film is preferably 0.99 to 1.03, and the Re (650) / Re (550) is preferably 0.98 to 1.02. In this case, the retardation film can have a laminated structure. Specifically, the retardation film functioning as a λ / 2 plate and the retardation film functioning as a λ / 4 plate are formed at a specific axis angle (for example, 50 ° to 70 °, preferably about 60 °). The arrangement can obtain characteristics close to the ideal anti-wavelength dispersion characteristics, and as a result, very excellent anti-reflection characteristics can be achieved. By using such a retardation film, the effect of the antireflection characteristic can be further exerted.

The retardation film preferably has a water absorption of 3% or less, more preferably 2.5% or less, and even more preferably 2% or less. By satisfying such a water absorption, it is possible to suppress the change in the display characteristics with time. The water absorption can be determined in accordance with JIS K 7209.

The absolute value of the retardation film-based photoelastic coefficient is preferably 40 × 10 ^-12 Pa ^-1 or less, and more preferably 35 × 10 ^-12 Pa ^-1 or less. By having the photoelastic coefficient in such a range, it is possible to prevent unevenness in the phase difference caused by heat. In addition, it is possible to prevent degradation of image quality from occurring.

The thickness of the retardation film is, for example, 70 μm or less, and preferably 30 μm to 60 μm. As long as it has such a thickness, appropriate mechanical strength can be provided even as a protective layer of a polarizing element.

The retardation film contains a polycarbonate-based resin. As the polycarbonate-based resin, any appropriate polycarbonate-based resin can be used. 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, and a polycarbonate resin derived from an alicyclic diol, an alicyclic dimethyl alcohol, A structural unit of at least one dihydroxy compound of a group consisting of di-, tri- or polyethylene glycol, and alkylene glycol or spirodiol. 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 a di-, Tri- or polyethylene glycol structural unit; further preferably, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a di-, tri- or polyethylene glycol Of structural unit. The polycarbonate-based resin may optionally contain structural units derived from other dihydroxy compounds. Further, details of the polycarbonate-based resin that can be preferably used in the present invention are described in, for example, Japanese Patent Laid-Open No. 2014-10291 and Japanese Patent Laid-Open No. 2014-26266, which are incorporated herein by reference. The record.

In one embodiment, a polycarbonate resin containing a unit structure derived from a dihydroxy compound represented by the following general formula (1) can be used.
[Chemical 1]

(In the general formula (1), R ¹ to R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and a substituted or unsubstituted carbon group having 6 to 20 carbon atoms. Cycloalkyl, or substituted or unsubstituted aryl having 6 to 20 carbons; X represents substituted or unsubstituted alkyl having 2 to 10 carbons, or substituted or unsubstituted 6 A cycloalkyl group of ~ 20, or a substituted or unsubstituted alkylene group of 6 to 20 carbon atoms; m and n are each independently an integer of 0 to 5).

Specific examples of the dihydroxy compound represented by the general formula (1) include 9,9-bis (4-hydroxyphenyl) fluorene and 9,9-bis (4-hydroxy-3-methylphenyl). , 9,9-bis (4-hydroxy-3-ethylphenyl) 茀, 9,9-bis (4-hydroxy-3-n-propylphenyl) 茀, 9,9-bis (4-hydroxy -3-isopropylphenyl) fluorene, 9,9-bis (4-hydroxy-3-n-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-second butylphenyl)茀, 9,9-bis (4-hydroxy-3-tert-butylphenyl) 茀, 9,9-bis (4-hydroxy-3-cyclohexylphenyl) 茀, 9,9-bis (4- Hydroxy-3-phenylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3 -Methylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isopropylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) ) -3-isobutylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-third 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-methylbenzene ) Fluorene, 9,9-bis (4- (3-hydroxy-2,2-dimethylpropoxy) benzene ) Fluorene and so on.

The polycarbonate-based resin may contain, in addition to the above-mentioned structural unit derived from a dihydroxy compound, isosorbide, isomannide, isoiditol, spirodiol, dialkylene glycol, The structural unit of dihydroxy compounds such as diethylene glycol (DEG), triethylene glycol (TEG), polyethylene glycol (PEG), and bisphenols.

The details of the polycarbonate-based resin containing a structural unit derived from a dihydroxy compound are described in, for example, Japanese Patent No. 5204200, Japanese Patent Laid-Open No. 2012-67300, Japanese Patent No. 3325560, and WO2014 / 061677. The description of this patent document is incorporated by reference in this specification.

In one embodiment, a polycarbonate resin containing an oligofluorene structural unit can be used. Examples of the polycarbonate-based resin containing an oligofluorene structural unit include a resin containing a structural unit represented by the following general formula (2) and / or a structural unit represented by the following general formula (3).
[Chemical 2]

(In the general formula (2) and the general formula (3), R ₅ and R ₆ are each independently a direct bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms (preferably a main chain) The carbon number on the alkylene group is 2 to 3.) R ₇ is a direct bond, substituted or unsubstituted carbonyl group of 1 to 4 (preferably, the carbon number on the main chain is 1 to 2). R ₈ ~ R ₁₃ are each independently a hydrogen atom, substituted or unsubstituted carbon number 1 to 10 (preferably 1 to 4, more preferably 1 to 2), Substituted or unsubstituted carbons with 4 to 10 (preferably 4 to 8, more preferably 4 to 7), substituted or unsubstituted carbons with 1 to 10 (preferably 1 to 4, More preferably 1 to 2) fluorenyl, substituted or unsubstituted carbon number 1 to 10 (preferably 1 to 4, more preferably 1 to 2) alkoxy, substituted or unsubstituted Aryloxy groups with 1 to 10 carbon atoms (preferably 1 to 4 and more preferably 1 to 2), and substituted or unsubstituted carbons with 1 to 10 carbon atoms (preferably 1 to 4 and more preferably 1 to 4) 2) fluorenyloxy group, substituted or unsubstituted amine group, substituted or unsubstituted vinyl group with 1 to 10 (preferably 1 to 4) carbon atoms, substituted or unsubstituted carbon number 1 ~ 10 (preferably 1 ~ 4) ethynyl, sulfur with substituent Promoter, having a silicon atom, a halogen atom, a nitro group, or a cyano group of. Also adjacent R ₈ ~ ₁₃ in at least two of the R groups bonded to each other to form a ring).

In one embodiment, the fluorene ring system included in the oligofluorene structural unit has a structure of all hydrogen atoms of R ₈ to R ₁₃ , or has a structure of R ₈ and / or R ₁₃ selected from a halogen atom, a fluorenyl group, and a nitro group. Any one of the group consisting of cyano, cyano, and sulfo, and R ₉ to R ₁₂ are each a hydrogen atom.

The details of the polycarbonate-based resin containing an oligofluorene structural unit are described in, for example, Japanese Patent Laid-Open No. 2015-212816. The description of this patent document is incorporated by reference in this specification.

The glass transition temperature of the polycarbonate-based resin is preferably 110 ° C to 150 ° C, and more preferably 120 ° C to 140 ° C. If the glass transition temperature is too low, heat resistance tends to deteriorate, dimensional changes may occur after film formation, and the image quality of the obtained image display device may be reduced. If the glass transition temperature is too high, the forming stability at the time of film formation may be deteriorated, and the transparency of the film may be impaired. The glass transition temperature was determined in accordance with JIS K 7121 (1987).

The molecular weight of the polycarbonate-based resin can be expressed by reduced viscosity. The reduced viscosity was measured by accurately preparing a polycarbonate concentration of 0.6 g / dL using dichloromethane as a solvent, and using a Ubbelohde viscosity tube at a temperature of 20.0 ° C ± 0.1 ° C. The lower limit of the reduced viscosity is usually preferably 0.30 dL / g, and more preferably 0.35 dL / g or more. The upper limit of the reduced viscosity is generally preferably 1.20 dL / g, more preferably 1.00 dL / g, and still more preferably 0.80 dL / g. If the reduced viscosity is less than the above-mentioned lower limit, there may be a problem that the mechanical strength of a molded product becomes small. On the other hand, if the reduced viscosity is larger than the above-mentioned upper limit value, there may be a problem that the fluidity at the time of molding is lowered and the productivity or moldability is lowered.

The retardation film is obtained, for example, by extending a film made of the polycarbonate resin. As a method for forming a film from a polycarbonate-based resin, any appropriate molding process can be adopted. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, a FRP (Fiber Reinforced Plastics) molding method, and a casting coating method. Method (for example, cast film method), calendering method, hot pressing method, and the like. An extrusion molding method or a casting coating method is preferred. This is because the smoothness of the obtained film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition or type of the resin to be used, the characteristics required for the retardation film, and the like. Further, as described above, since a large number of film products are being sold on the market, the commercially available film can also be directly provided in the stretching process.

The thickness of the resin film (unstretched film) can be set to any appropriate value according to the required thickness of the retardation film, the required optical characteristics, the stretching conditions described later, and the like. It is preferably 50 μm to 300 μm.

The above-mentioned stretching can adopt any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching magnification, and stretching direction). Specifically, various extension methods such as free-end extension, fixed-end extension, free-end contraction, and fixed-end contraction can be used individually or simultaneously or sequentially. The extending direction can also be performed in various directions or dimensions such as a long direction, a width direction, a thickness direction, and an oblique direction. The elongation temperature is preferably Tg-30 ° C to Tg + 60 ° C, and more preferably Tg-10 ° C to Tg + 50 ° C relative to the glass transition temperature (Tg) of the resin film.

By appropriately selecting the above-mentioned extension method and extension conditions, a retardation film having the above-mentioned required optical characteristics (for example, refractive index characteristics, in-plane retardation, and Nz coefficient) can be obtained.

In one embodiment, the retardation film is made by uniaxially extending the resin film or uniaxially extending the fixed end. As a specific example of the uniaxial extension of the fixed end, a method of moving the resin film in the long-side direction and extending it in the width direction (lateral direction) can be mentioned. The stretching ratio is preferably 1.1 to 3.5 times.

In another embodiment, the retardation film can be produced by continuously extending a long resin film obliquely in a direction at an angle θ with respect to the long-side direction. By using oblique extension, a long stretched film having an alignment angle (late phase axis in the direction of angle θ) with an angle θ with respect to the long side direction of the film can be obtained, for example, when laminated with a polarizing element. Roll-to-roll, which simplifies the process. In addition, the angle θ may be an angle formed between the absorption axis of the polarizing element of the circular polarizer and the retardation axis of the retardation film. As described above, the angle θ is preferably 38 ° to 52 °, more preferably 42 ° to 48 °, and even more preferably about 45 °.

E. Adhesive layer polarizing element and retardation film are bonded together via an adhesive layer formed on the easy-adhesion layer. The adhesive layer can contain any appropriate adhesive. The thickness of the adhesive layer is preferably 20 nm to 1000 nm, and more preferably 100 nm to 700 nm.

The refractive index difference between the adhesive layer and the retardation film is preferably 0.01 or less, and more preferably 0.005 or less. When the refractive index difference between the adhesive layer and the retardation film is within the above range, the excellent anti-reflection characteristics of the circular polarizing plate can be further maintained.

The adhesive is preferably isotropic with transparency and optical properties. As the adhesive, any appropriate one can be used. Specific examples include an aqueous adhesive, a solvent-based adhesive, an emulsion-based adhesive, a solventless adhesive, an active energy ray-curable adhesive, and a thermosetting adhesive. Examples of the active energy ray-curable adhesive include an electron beam-curable adhesive, an ultraviolet-curable adhesive, and a visible light-curable adhesive. It is preferable to use a thermosetting adhesive or a UV-curable adhesive containing a PVA-based resin.

Examples of the PVA-based resin contained in the thermosetting adhesive containing a PVA-based resin include a PVA resin and a PVA resin containing an ethylamidine group. A PVA resin containing an ethylamidine group is preferred. This is because the adhesion between the polarizing element and the protective film can be further improved, and the durability can be improved.

The above-mentioned acetamidine-containing PVA resin is obtained by, for example, reacting a PVA-based resin with diketene by any method. Specific examples include a method of adding diketene to a dispersion in which PVA-based resin is dispersed in a solvent such as acetic acid; Method: A method of directly contacting a diketene gas or a liquid diketene with a PVA-based resin.

The thermosetting adhesive containing the PVA-based resin may contain a crosslinking agent. As the cross-linking agent, any appropriate cross-linking agent can be used. It is preferred that the compound contains at least two functional groups having reactivity with the PVA-based resin. As the functional group containing at least two functional groups having reactivity with a PVA-based resin, those listed as the cross-linking agent of the easily-adhesive layer can be used.

The compounding quantity of the said crosslinking agent can be suitably set according to the kind of said PVA-type resin, etc. It is typically about 10 to 60 parts by weight, and preferably 20 to 50 parts by weight, based on 100 parts by weight of the PVA-based resin. This is because the adhesiveness can be made excellent. Moreover, when the compounding quantity of a crosslinking agent is large, reaction of a crosslinking agent may progress in a short time, and an adhesive agent may gel. As a result, the application time (application period) as an adhesive may be extremely short, and industrial use may become difficult.

The thermosetting adhesive containing the PVA-based resin can contain a metal compound colloid. The metal compound colloid may be one in which metal compound fine particles are dispersed in a dispersion medium, and may be one having static stability due to mutual repulsion due to the same kind of charge of the fine particles, thereby having permanent stability. By containing such a metal compound colloid, for example, even when the compounding amount of the said crosslinking agent is large, the adhesive composition excellent in stability can be obtained.

The average particle diameter of the fine particles forming the above-mentioned metal compound colloid may be any appropriate value as long as it does not adversely affect optical characteristics such as polarization characteristics. It is preferably 1 nm to 100 nm, and further preferably 1 nm to 50 nm. This is because the fine particles can be uniformly dispersed in the adhesive layer to ensure the adhesiveness, and the occurrence of crack point defects can be suppressed. Moreover, the so-called "crack point defect" refers to light leakage.

As the metal compound, any appropriate compound can be adopted. Examples include metal oxides such as alumina, silica, zirconia, and titanium oxide; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, and calcium phosphate; diatomite, talc, and clay , Kaolin and other minerals. As described later, a colloid of a metal compound having a positive charge is preferably used in the present invention. Examples of the metal compound include alumina and titanium oxide, and alumina is particularly preferred.

The metal compound colloid is typically dispersed in a dispersion medium and exists in the state of a colloidal solution. Examples of the dispersion medium include water and alcohols. The solid content concentration in the colloidal solution is typically about 1% to 50% by weight, and preferably 1% to 30% by weight. The colloidal solution can contain an acid such as nitric acid, hydrochloric acid, or acetic acid as a stabilizer.

The compounding amount of the metal compound colloid (solid matter component) is preferably 200 parts by weight or less, more preferably 10 parts by weight to 200 parts by weight, and still more preferably 20 parts by weight to 175 parts with respect to 100 parts by weight of the polyvinyl alcohol resin. It is particularly preferably 30 parts by weight to 150 parts by weight. This is because it is possible to suppress the occurrence of crack point defects while ensuring adhesion.

Specific examples of the ultraviolet-curable adhesive include a (meth) acrylate-based adhesive. The (meth) acrylate means an acrylate and / or a methacrylate. Examples of the curable component in the (meth) acrylate-based adhesive include a compound having a (meth) acrylfluorenyl group and a compound having a vinyl group. Preferred examples of the compound having a (meth) acrylfluorenyl group include an N-substituted fluorenamine monomer represented by the following formula (4).
CH ₂ = C (R ¹⁴ ) -CONH _2-m- (XOR ¹⁵ ) _m (4)
Here, R ¹⁴ represents a hydrogen atom or a methyl group; X represents a -CH ₂ -group or -CH ₂ CH ₂ -group, and R ¹⁵ represents a-(CH ₂ ) _n -H group (where n is 0, 1, or 2). ); M represents 1 or 2.

The (meth) acrylate-based adhesive may further contain a monomer having two or more carbon-carbon double bonds, and preferably further contains a polyfunctional (meth) acrylate-based monomer as a curable component. More preferably, it is a single-system hydrophobic having two or more carbon-carbon double bonds. The (meth) acrylate-based adhesive may contain monofunctional (meth) acrylates having various aromatic rings and hydroxyl groups, urethane (meth) acrylates, and polyester (meth) acrylates. Ester and the like serve as a curable component.

The (meth) acrylate-based adhesive may contain any appropriate copolymerization component.

The ultraviolet-curable adhesive further contains a polymerization initiator. The content of the polymerization initiator is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and even more preferably 0.1 to 3 parts by weight with respect to the total amount of the ultraviolet curing adhesive.

As long as the ultraviolet curing type adhesive does not impair the object and effect of the present invention, various additives can be blended as other optional components. Examples of the additives include various polymers or oligomers, polymerization inhibitors, polymerization initiation aids, leveling agents, wettability improvers, surfactants, plasticizers, ultraviolet absorbers, and silane coupling agents. , Inorganic fillers, pigments, dyes, etc.

As another specific example of the active energy ray-curable adhesive, a photocationic curable adhesive having an epoxy compound and a photoacid generator as a main component may be mentioned. Examples of the epoxy compound that can be used include compounds described in [0031] to [0085] of Japanese Patent Laid-Open No. 2010-145537. Examples of the photoacid generator include compounds described in [0080] to [0095] of Japanese Patent Laid-Open No. 2009-013316. The descriptions of these publications are incorporated by reference in this specification.

F. Protective film The circular polarizing plate of the present invention is provided with any appropriate layer in addition to the above-mentioned polarizing element, easy-adhesion layer, and retardation film. For example, a protective film is mentioned. The protective film is formed from any appropriate film that can be used as a protective film for a polarizing element. Specific examples of the material of the main component of the film include cellulose-based resins such as triethylammonium cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, and polymer-based Transparent resins such as fluorene imide, polyether fluorene, polyfluorene, polystyrene, polynorbornene, polyolefin, (meth) acrylic, and acetic acid. In addition, heat-curable resins such as (meth) acrylic, urethane-based, urethane-based (meth) acrylic, epoxy-based, and silicone-based, or UV-curable resins can also be cited . Other examples include glassy polymers such as siloxane polymers. In addition, a polymer film described in Japanese Patent Laid-Open No. 2001-343529 (WO01 / 37007) may be used. As a material of the film, for example, a thermoplastic resin having a substituted or unsubstituted imine group in a side chain, and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in a side chain can be used. Examples of the resin composition include a resin composition having an alternating copolymer containing isobutylene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded product of the resin composition.

The circular polarizing plate of the present invention is typically arranged on the viewing side of the display device, and the protective film is typically arranged on the viewing side. Therefore, a surface treatment such as a hard coating treatment, an anti-reflective treatment, an anti-sticking treatment, or an anti-glare treatment may be performed on the protective film as necessary.

The thickness of the protective film can be any appropriate thickness. The thickness of the protective film is, for example, 10 μm to 100 μm, and preferably 30 μm to 90 μm. When the surface treatment is performed, the thickness of the protective film is a thickness including the thickness of the surface treatment layer.

G. Display Device The circular polarizing plate of the present invention can be applied to any suitable application. Specifically, it can be applied to display devices such as a liquid crystal display device and an organic EL display device. This display device includes, for example, a display element and the above-mentioned circularly polarizing plate arranged on the viewing side of the display element. The circular polarizing plate is arranged so that the retardation layer is on the display element side.
Examples

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited by these examples. The measurement method of each characteristic is as follows. In addition, "part" and "%" in an Example and a comparative example are a weight basis as long as it is not specifically stated otherwise.

(1) Thickness Using a dial gauge (manufactured by PEACOCK, product name "DG-205 type pds-2"), the thickness of the retardation film was measured.
(2) The refractive index was measured using an Abbe refractometer (DR-M2, manufactured by Atago). The measurement was performed under the environment of 23 ° C, and the measurement wavelength was set to 589 nm.
(3) Initial bonding force (90 ° bonding force)
The circular polarizing plates obtained in the examples and comparative examples were cut out in a size of 200 mm parallel to the absorption axis direction of the polarizing element and 20 mm in the orthogonal direction. A cutter was used between the retardation film and the polarizing element. A cut is made, and the circular polarizing plate is attached to a glass plate. Using a Tensilon universal testing machine RTC manufactured by A & D Co., Ltd., the retardation film and the polarizing element were peeled at a peeling speed of 1000 mm / min at a direction of 90 degrees, and the peeling strength was measured to make it a 90 ° adhesive force.
(4) Reflectivity of circularly polarizing plate Apply an adhesive (manufactured by Nitto Denko Corporation, trade name: No. 7) on the reflecting plate so that the thickness after drying is 15 μm. Examples and comparisons The retardation film of the circular polarizing plate obtained in the example is bonded to the reflecting plate. Further, a polarizing plate (manufactured by Nitto Denko Corporation, trade name "REGQS1298DUHC3") was attached to the retardation plate so that the angle formed by the retardation axis of the retardation plate and the absorption axis of the polarizing plate was 45 °. Then, the reflectance (SCI value) was measured using a spectrophotometer "CM-2600d" manufactured by Konica Minolta.
(5) Existence of peeling The circular polarizing plates obtained in the examples and comparative examples were observed with an optical microscope, and the presence or absence of peeling between the polarizing element and the retardation film was observed. In addition, after the circular polarizing plates obtained in the examples and comparative examples were left in an environment of 85 ° C. for 500 hours, the presence or absence of peeling was confirmed using an optical microscope (heating test). Similarly, the circularly polarizing plates obtained in the examples and comparative examples were left in an environment of 60 ° C. and 95% RH for 240 hours, and then the presence or absence of peeling was confirmed using an optical microscope (heating humidification test). The case where peeling was not confirmed was set as x, and the case where peeling was confirmed visually was made into x.
(6) Appearance (uneven bars)
After the circular polarizing plates obtained in the examples and comparative examples were left in an environment of 60 ° C. and 95% RH for 240 hours, the surface of the circular polarizing plates was visually confirmed. The case where the stripe unevenness cannot be visually recognized in the dark room is set to ◎, and the case where it is visually recognizable in the dark room but cannot be recognized in a normal use environment is set.

(Production Example 1) Production of retardation film 1 38.06 parts by weight (0.059 mol) of bis [9- (2-phenoxycarbonylethyl) fluorene-9-yl] methane, isosorbide (manufactured by Roquette Fleur, Trade name "POLYSORB") 53.73 parts by weight (0.368 mol), 1,4-cyclohexanedimethanol (cis, trans mixture, manufactured by SK Chemicals) 9.64 parts by weight (0.067 mol), diphenyl carbonate (Mitsubishi 81.28 parts by weight (0.379 mol) and 3.83 × 10 ^-4 parts by weight (2.17 × 10 ^-6 mol) of calcium acetate monohydrate as a catalyst were introduced into the reaction vessel, and the inside of the reaction device was decompressed with nitrogen. Replacement. Under a nitrogen atmosphere, the raw materials were dissolved while stirring at 150 ° C. for about 10 minutes. It took 30 minutes to raise the temperature to 220 ° C, and reacted under normal pressure for 60 minutes as a step in the first stage of the reaction. Then, it took 90 minutes to depressurize the pressure from normal pressure to 13.3 kPa and maintained it at 13.3 kPa for 30 minutes. The generated phenol was extracted out of the reaction system. Then, it took 15 minutes to raise the temperature of the heating medium to 240 ° C, and it took 15 minutes to reduce the pressure to below 0.10 kPa, and the generated phenol was extracted out of the reaction system as a step in the second stage of the reaction. After the specific stirring torque is reached, the pressure is returned to normal pressure with nitrogen and the reaction is stopped. The generated polyester carbonate is extruded into water, and the strand is cut to obtain polycarbonate resin particles. Then, a film was produced from the obtained polycarbonate-based resin particles. The refractive index of the obtained film (unstretched) was 1.53.
The film was stretched obliquely to obtain a retardation film (thickness: 57 μm, photoelastic coefficient: 16 × 10 ^-12 Pa ^-1 , Re (450): 120 nm, Re (550): 140 nm, Re (450) / Re (550): 0.86). At this time, the extending direction is 45 ° with respect to the longitudinal direction of the film. In addition, the stretch ratio was adjusted to 2 to 3 times so that the obtained retardation film exhibited a retardation of λ / 4. The stretching temperature was 148 ° C (that is, Tg + 5 ° C of the unstretched modified polycarbonate film).

(Production Example 2) Production of retardation film 2 was based on 81.98 parts by mass of isosorbide, 47.19 parts by mass of tricyclodecanedimethanol, 175.1 parts by mass of diphenyl carbonate, and a 0.2 mass% aqueous solution of cesium carbonate as a catalyst. 0.979 parts by mass was put into a reaction vessel, and the temperature of the heating tank was heated to 150 ° C. under a nitrogen atmosphere, and the raw materials were dissolved (about 15 minutes) as needed as the first step of the reaction while stirring.

Then, while the pressure was set to 13.3 kPa from the normal pressure, and it took 1 hour to raise the temperature of the heating tank to 190 ° C, the generated phenol was drawn out of the reaction vessel.
After the entire reaction vessel was held at 190 ° C for 15 minutes, the pressure in the reaction vessel was set to 6.67 kPa, and the temperature of the heating tank was raised to 230 ° C in 15 minutes. The generated phenol was extracted outside the reaction vessel as the second stage. step. As the stirring torque of the stirrer increased, it took 8 minutes to increase the temperature to 250 ° C. In order to remove the phenol generated, the pressure in the reaction vessel was reduced to 0.200 kPa or less. After the specific stirring torque is reached, the reaction is ended, and the produced reactant is extruded into water to obtain pellets of a polycarbonate copolymer.
Use a single-shaft extruder (manufactured by ISUZU Chemical Machinery Co., Ltd., screw diameter 25 mm, cylinder set temperature: 220 ° C), T-die (width 200 mm, set temperature: 220 ° C), cooling roller (set temperature : 120 ~ 130 ° C) and a film forming device of a scooping machine, the obtained particles are made into a film with a thickness of 100 μm. The refractive index of the obtained film (unstretched) was 1.51.
The obtained film was diagonally extended to obtain a retardation film 2 (thickness: 30 μm, photoelastic coefficient: 30 × 10 ^-12 Pa ^-1 , Re (450): 140 nm, Re (550): 140 nm, Re (450) / Re (550): 1.0). At this time, the extending direction was set to be 45 ° with respect to the longitudinal direction of the film. In addition, the stretch ratio was adjusted to 2 to 3 times so that the obtained retardation film exhibited a retardation of λ / 4.

(Manufacturing Example 3) A polarizing element was produced such that a polymer film (manufactured by Kuraray (Stock Corporation), trade name "VF-PE-A # 3000") with a polyvinyl alcohol-based resin having a thickness of 30 μm as a main component was facing the film Tensions were applied to the long side in the five baths under the conditions of (1) to (5) below, and stretched so that the final stretch ratio was 6.2 times the original length of the film. This stretched film was dried in an air-circulating drying oven at 40 ° C for 1 minute to prepare a polarizing element.
＜ Conditions ＞
(1) Swelling bath: 30 degrees pure water.
(2) Dyeing bath: an aqueous solution containing 30 degrees of iodine in an amount of 0.035 parts by weight relative to 100 parts by weight of water and 0.2 parts by weight of potassium iodide in 100 parts by weight of water.
(3) The first crosslinking bath: a 40-degree aqueous solution containing 3% by weight of potassium iodide and 3% by weight of boric acid.
(4) The second crosslinking bath: a 60-degree aqueous solution containing 5% by weight of potassium iodide and 4% by weight of boric acid.
(5) Water bath: a 25-degree aqueous solution containing 2.6% by weight of potassium iodide.

[Example 1]
(Preparation of easy-adhesive layer-forming composition 1)
5 parts by weight of a polyurethane resin (manufactured by Daiichi Kogyo Co., Ltd., trade name: Superflex 210) was added and mixed with 5 parts by weight of a cross-linking agent (manufactured by DIC Corporation, trade name: WATERSOL S695) to prepare an easy-adhesive layer forming composition.
(Preparation of Adhesive Composition 1)
50 parts by weight of methylolmelamine with respect to 100 parts by weight of a polyvinyl alcohol-based resin having an acetamidine group (average degree of polymerization of 1200, a degree of saponification of 98.5 mol%, and a degree of acetamidine of 5 mol%) Parts were dissolved in pure water to prepare an aqueous solution with a solid component concentration of 3.7% by weight. Alumina colloids with a positive charge (average particle diameter of 15 nm) were added to 10% by weight of the solid component content based on 100 parts by weight of the aqueous solution. 18 parts by weight of an aqueous solution was prepared.

The easy-adhesive layer-forming composition was coated on one surface of the retardation film 1 to form an easy-adhesive layer having a thickness of 100 nm.
Furthermore, a TAC film (on the TAC film (Konecranes) of the TAC film) was coated on one surface of the polarizer with a thickness of 0.1 μm after drying, and was hard-coated through the adhesive. Manufactured by Caminolta, trade name: KC2UA) The hard-coated side is applied to the polarizing element.
Next, the above-mentioned adhesive composition 1 was coated on the easy-adhesion layer so that the thickness after drying was 0.1 μm, and the polarizing element and the retardation film of the laminated body of the polarizing element and the TAC film were laminated to obtain a circular shape. Polarizer. Furthermore, the retardation film is bonded so that the retardation axis of the retardation film and the absorption axis of the polarizing element form an angle of 45 °. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 2]
A circularly polarizing plate was produced in the same manner as in Example 1 except that the amount of the crosslinking agent added was 15 parts by weight in the easy-adhesive layer forming composition. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 3]
Except that an oxazoline group-containing water-soluble polymer (produced by Nippon Catalytic Corporation, trade name: Epocros WS700) was used as a crosslinking agent included in the easy-adhesive layer-forming composition, a circle was produced and obtained in the same manner as in Example 1. Polarizer. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 4]
A circularly polarizing plate was produced in the same manner as in Example 3, except that the amount of the crosslinking agent added to the easy-adhesive layer-forming composition was 15 parts by weight. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 5]
A circularly polarizing plate was produced in the same manner as in Example 1 except that the retardation film 2 was used instead of the retardation film 1. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 6]
A circularly polarizing plate was produced in the same manner as in Example 2 except that the retardation film 2 was used instead of the retardation film 1. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 7]
A circularly polarizing plate was produced in the same manner as in Example 3 except that the retardation film 2 was used instead of the retardation film 1. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 8]
A circularly polarizing plate was produced in the same manner as in Example 4 except that the retardation film 2 was used instead of the retardation film 1. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 9]
(Preparation of Adhesive Composition 2)
Active energy ray hardening components (10 parts by weight of hydroxyethylpropenamide, 30 parts by weight of acrylomorphine, and 54.5 parts by weight of 1,9-nonanediol diacrylate), a bubble inhibitor (polyorganosiloxane Manufactured by BYK-Chemie Japan, trade name: BYK-UV 3570)) 0.50 parts by weight, 3 parts by weight of IRGACURE907 (manufactured by BASF) as a polymerization initiator, and 2 parts by weight of KAYACURE DETX-S (manufactured by Nippon Kayaku Co., Ltd.) Parts were mixed to prepare an adhesive composition 2.
A circularly polarizing plate was produced in the same manner as in Example 3 except that the obtained adhesive composition 2 was used to form an adhesive layer having a thickness of 0.50 μm. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

[Example 10]
A circularly polarizing plate was produced in the same manner as in Example 4 except that the above-mentioned adhesive composition 2 was used to form an adhesive layer having a thickness of 0.50 μm. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

(Comparative example 1)
A circularly polarizing plate was produced in the same manner as in Example 1 except that a crosslinking agent was not added to the easy-adhesive layer-forming composition. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

(Comparative example 2)
A circularly polarizing plate was produced in the same manner as in Example 1 except that the easy-adhesive layer forming composition 1 was replaced with a silane coupling agent (manufactured by Shin-Etsu Silicone Co., Ltd., trade name: KBM603) to form an easy-adhesive layer having a thickness of 50 nm. The evaluation results of the obtained circular polarizing plates are shown in Table 1.

(Comparative example 3)
A circularly polarizing plate was produced in the same manner as in Example 5 except that a crosslinking agent was not added to the easy-adhesive layer-forming composition. The evaluation results of the obtained circular polarizing plates are shown in Table 1.
Further, a circularly polarizing plate was prepared in which the thickness of the easy-adhesive layer was changed to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plate was evaluated in the same manner. The results are shown in Table 1.

(Comparative Example 4)
A circularly polarizing plate was produced in the same manner as in Example 5 except that the easy-adhesive layer forming composition 1 was replaced with a silane coupling agent (manufactured by Shin-Etsu Silicone Co., Ltd., trade name: KBM603) to form an easy-adhesive layer having a thickness of 50 nm. The evaluation results of the obtained circular polarizing plates are shown in Table 1.

(Comparative example 5)
In addition to replacing the easy-adhesive layer forming composition 1, a modified polyolefin resin (manufactured by Unitika (stock), trade name is used so that the mass ratio (solid content) of the polyolefin-based component to the polyvinyl alcohol-based component is 90:10) "ARROWBASE SE-1030N"), an aqueous solution of a polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200"), and an easy-adhesive layer forming composition mixed with pure water to form an easy-adhesive layer having a thickness of 500 nm Other than that, a circularly polarizing plate was produced in the same manner as in Example 5. The evaluation results of the obtained circular polarizing plates are shown in Table 1.

(Comparative Example 6)
A circularly polarizing plate was produced in the same manner as in Comparative Example 5 except that an easy-adhesive layer having a thickness of 800 nm was formed. The evaluation results of the obtained circular polarizing plates are shown in Table 1.

[Table 1]

[Evaluation]
As clearly shown in Table 1, in the circular polarizing plate of the present invention, sufficient adhesion between the polarizing element and the retardation film is ensured. In such a circularly polarizing plate, sufficient adhesion can be maintained even when placed under heating conditions and heating and humidifying conditions. Furthermore, the excellent anti-reflection characteristics of the circularly polarizing plate are maintained. In particular, in Examples 1 to 4 using a retardation film having a reverse dispersion characteristic, the anti-reflection characteristics of the circularly polarizing plate were further exerted.
[Industrial availability]

The circular polarizing plate of the present invention is preferably used for display devices such as a liquid crystal display device and an organic EL display device. The circular polarizing plate of the present invention can be preferably used regardless of the type of surface treatment.

10‧‧‧ polarizing element

20‧‧‧ Easy to attach layer

30‧‧‧ retardation film

40‧‧‧ Adhesive layer

100‧‧‧ circular polarizer

FIG. 1 is a schematic cross-sectional view of a circular polarizing plate according to a preferred embodiment of the present invention.

Claims (8)

A circular polarizing plate, which sequentially includes a polarizing element, An easy-adhesive layer containing a polyurethane resin having a carboxyl group and a crosslinking agent, and Retardation film containing polycarbonate resin and functioning as a λ / 4 plate; and The refractive index difference between the retardation film and the easy-adhesion layer is 0.01 or less. The circular polarizing plate according to claim 1, wherein the cross-linking agent is a compound having a methylol group or a compound having an oxazoline group. For example, the circular polarizer of claim 1 or 2, wherein the thickness of the easy-adhesion layer is less than 1 μm. For example, the circularly polarizing plate according to any one of claims 1 to 3, wherein the retardation film satisfies the relationship of Re (450) <Re (550). For example, the circular polarizing plate according to any one of claims 1 to 4, wherein a 90 ° adhesive force between the retardation film and the easy-adhesion layer is 1.0 N / 15 mm or more. For example, the circular polarizing plate according to any one of claims 1 to 5, wherein the 90 ° adhesive force between the polarizing element and the easy-adhesion layer is 1.0 N / 15 mm or more. For example, the circular polarizing plate according to any one of claims 1 to 6, wherein the 90 ° adhesive force between the polarizing element and the easy-adhesion layer after being left for 500 hours at 85 ° C is 1.0 N / 15mm or more. For example, the circular polarizing plate according to any one of claims 1 to 7, wherein the 90 ° adhesive force between the polarizing element and the easy-adhesive layer after being left for 240 hours at 60 ° C and 95% RH is 0.5 N / 15mm or more. .