JP7305306B2 - circular polarizer - Google Patents

Description

The present invention relates to a circularly polarizing plate.

Display devices such as liquid crystal display devices and organic EL display devices use a circularly polarizing plate equipped with a retardation film that functions as a polarizer and a λ / 4 plate for the purpose of preventing reflection of external light and the like. there is In recent years, a retardation film using a polycarbonate resin has been proposed (Patent Document 1). However, a retardation film using a polycarbonate-based resin has room for improvement in adhesion to other layers such as a polarizer.

In order to improve the adhesion of the film, it has been proposed to form an easy-adhesion layer on one surface of the film (Patent Document 2). However, when applied to a retardation film used for a circularly polarizing plate, there is a problem that the antireflection properties of the circularly polarizing plate are not sufficiently exhibited due to the formation of the easy-adhesion layer.

JP 2015-212816 A JP 2014-10292 A

The present invention has been made to solve the above-described conventional problems, and its object is to ensure adhesion between a polarizer and a retardation film, and to maintain excellent antireflection properties. An object of the present invention is to provide a circularly polarizing plate.

The circularly polarizing plate of the present invention includes a polarizer, an easy-adhesion layer containing a urethane resin having a carboxyl group and a cross-linking agent, and a retardation film that contains a polycarbonate resin and functions as a λ / 4 plate, in this order. and a refractive index difference between the retardation film and the easily adhesive layer is 0.01 or less.
In one embodiment, the cross-linking agent is a compound having a methylol group or a compound having an oxazoline group.
In one embodiment, the easily adhesive layer has a thickness of less than 1 μm.
In one embodiment, the retardation film satisfies the relationship Re(450)<Re(550).
In one embodiment, the 90° adhesive strength between the retardation film and the easy-adhesion layer is 1.0 N/15 mm or more.
In one embodiment, the 90° adhesive force between the polarizer and the easy-adhesion layer is 1.0 N/15 mm or more.
In one embodiment, the 90° adhesive force between the polarizer and the easy-adhesion layer is 1.0 N/15 mm or more after being placed at 85° C. for 500 hours.
In one embodiment, the 90° adhesive strength between the polarizer and the easy-adhesion layer after being placed under conditions of 60° C. and 95% RH for 240 hours is 0.5 N/15 mm or more.

ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness of a polarizer and a retardation film can fully be ensured. Furthermore, even after being subjected to the durability test, it is possible to prevent problems such as undercoating cohesive failure or interfacial peeling, and polarization cracks. Also, the excellent antireflection properties of the circularly polarizing plate can be maintained. Furthermore, in the circularly polarizing plate of the present invention, scratches on the surface of the retardation film can be filled with the easily adhesive layer. Therefore, the smoothness of the retardation film surface can be maintained. In addition, the circularly polarizing plate of the present invention can preferably exhibit antireflection properties regardless of the type of surface treatment.

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

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

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the in-plane direction orthogonal to the slow axis (i.e., fast axis direction) and "nz" is the refractive index in the thickness direction.
Unless otherwise specified, the "refractive index" of a film that exhibits birefringence after stretching refers to a value calculated by (nx+ny+nz)/3.
(2) In-plane retardation (Re)
“Re(550)” is the in-plane retardation of the film measured at 23° C. with light having a wavelength of 550 nm. Re (550) is obtained by the formula: Re=(nx−ny)×d, where d (nm) is the thickness of the film. “Re(450)” is the in-plane retardation of the film measured at 23° C. with light having a wavelength of 450 nm.
(3) Thickness direction retardation (Rth)
“Rth(550)” is the retardation in the thickness direction of the film measured at 23° C. with light having a wavelength of 550 nm. Rth (550) is determined by the formula: Rth=(nx−nz)×d, where d (nm) is the thickness of the film. "Rth(450)" is the retardation in the thickness direction of the film measured at 23°C with light having a wavelength of 450 nm.
(4) Nz Coefficient The Nz coefficient is obtained by Nz=Rth/Re.

A. Circularly polarizing plate The circularly polarizing plate of the present invention includes a polarizer, 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. Prepare in this order. Practically, an adhesive layer is formed between the easy-adhesion layer and the polarizer. By forming the easily adhesive layer as described above, in the circularly polarizing plate of the present invention, sufficient adhesion between the polarizer and the retardation film containing the polycarbonate resin can be ensured. Furthermore, sufficient adhesion can be ensured even after the endurance test with heating and heating and humidification.

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

In the circularly polarizing plate of the present invention, the refractive index difference between the retardation film and the easily adhesive layer is 0.01 or less, preferably 0.005 or less. When the refractive index difference between the retardation film and the easy-adhesion film is 0.01 or less, the excellent antireflection properties of the circularly polarizing plate can be maintained. The smaller the difference in refractive index between the retardation film and the easy-adhesion layer, the better, and it is particularly preferred that the difference in refractive index 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). preferable.

In the circularly polarizing plate of the present invention, the 90° adhesive strength between the retardation film and the easy-adhesion layer is preferably 1.0 N/15 mm or more, more preferably 2.0 N/15 mm or more. Further, the 90° adhesive strength between the polarizer and the easy-adhesion layer is 1.0 N/15 mm or more, more preferably 2.0 N/15 mm or more. If the 90° adhesive strength between the retardation film and the easy-adhesion layer and between the polarizer and the easy-adhesion layer is within the above range, sufficient adhesion between the polarizer and the retardation film can be ensured. In this specification, the 90° adhesive strength can be measured by the method described in Examples.

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

B. Polarizer Any appropriate polarizer can be employed as the polarizer 10 . For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films. In addition, polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with dichroic substances such as iodine and dichroic dyes, and dehydrated PVA and dehydrochlorinated polyvinyl chloride films. A polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is preferably used because of its excellent optical properties.

The dyeing with iodine is performed by, for example, immersing the PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial drawing is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or may be performed while dyeing. Moreover, you may dye after extending|stretching. If necessary, the PVA-based film is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be washed away, but also the PVA-based film can be swollen to remove uneven dyeing. can be prevented.

Specific examples of the polarizer obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and the resin A polarizer obtained by using a laminate with a PVA-based resin layer formed by coating on a substrate can be mentioned. A polarizer obtained by using a laminate of a resin base material and a PVA-based resin layer formed by coating on the resin base material is obtained, for example, by applying a PVA-based resin solution to the resin base material and drying the resin base material. forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Furthermore, stretching may further include stretching the laminate in air at a high temperature (eg, 95° C. or higher) before stretching in an aqueous boric acid solution, if necessary. The obtained resin substrate/polarizer laminate may be used as it is (that is, the resin substrate may be used as an inner protective layer provided between the retardation film and the polarizer), or the resin substrate/polarizer The resin substrate (resin layer) may be peeled off from the secondary laminate, and any appropriate protective layer may be laminated on the peeled surface as an inner protective layer according to the purpose. Details of a method for manufacturing such a polarizer are described, for example, in Japanese Patent Application Laid-Open No. 2012-73580. The publication is incorporated herein by reference in its entirety.

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

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is preferably 42.0% to 46.0%, more preferably 43.0% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, still more preferably 99.9% or higher.

C. Easy-Adhesion Layer The easy-adhesion layer 20 contains a urethane-based resin having a carboxyl group and a cross-linking agent. The easy-adhesion layer is formed on one surface of the retardation film. For example, a circularly polarizing plate can be 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 polarizer. By including the urethane-based resin having a carboxyl group and the cross-linking agent in the easy-adhesion layer, the adhesion between the polarizer and the retardation film including the polycarbonate-based resin is improved. Furthermore, this adhesion can be maintained even when the circularly polarizing plate is subjected to an endurance test. Further, in the circularly polarizing plate of the present invention, the difference in refractive index between the retardation film and the easily adhesive layer is 0.01 or less. Therefore, the excellent antireflection properties of the obtained circularly polarizing plate can be maintained.

C-1. Urethane Resin Having Carboxyl Group The urethane resin has a carboxyl group. By having a carboxyl group, it is possible to provide a circularly polarizing plate having excellent adhesion (particularly at high temperatures) between the polarizer and the retardation film. A urethane-based resin is typically obtained by reacting a polyol and a polyisocyanate. The polyol is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any suitable polyol can be adopted. Examples thereof include polyacryl polyol, polyester polyol, polyether polyol and the like. These may be used alone or in combination of two or more.

A urethane resin having a carboxyl group can be obtained, for example, by reacting the polyol and the polyisocyanate with a chain lengthening agent having a free carboxyl group. Examples of the chain lengthening agent having a free carboxyl group include dihydroxycarboxylic acid, dihydroxysuccinic acid and the like. Dihydroxycarboxylic acids include, for example, dialkylolalkanoic acids such as dimethylolalkanoic acid (eg, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolpentanoic acid). These may be used alone or in combination of two or more.

In the production of the urethane resin, other polyols and other chain lengthening agents may be reacted in addition to the above components. Other polyols include, for example, sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, trimethylol. Examples thereof include polyols having 3 or more hydroxyl groups such as ethane, trimethylolpropane and pentaerythritol. Other chain lengthening agents include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6 - glycols such as hexanediol and propylene glycol; aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine and aminoethylethanolamine; isophoronediamine and 4,4'-dicyclohexylmethanediamine; alicyclic diamines; aromatic diamines such as xylylenediamine and tolylenediamine;

C-2. Cross-linking agent Any appropriate cross-linking agent can be used as the cross-linking agent. Preferably, a cross-linking agent capable of reacting with a carboxyl group and a cross-linking agent capable of reacting with a polyvinyl alcohol-based resin are used. Cross-linking agents capable of reacting with carboxyl groups include polymers having groups capable of reacting with carboxyl groups. Examples of groups capable of reacting with carboxyl groups include organic amino groups, oxazoline groups, epoxy groups, carbodiimide groups, aldehyde groups, and methylol groups. The crosslinker is preferably a polymer with oxazoline groups. A polymer having an oxazoline group has a long pot life at room temperature when mixed with the above urethane resin, and the cross-linking reaction proceeds by heating, resulting in good workability.

Any appropriate polymer can be adopted as the polymer. Examples thereof include acrylic polymers, styrene/acrylic polymers, and the like. Acrylic polymers are preferred. Adhesion between the polarizer and the retardation film can be further improved by using the acrylic polymer.

The cross-linking agent capable of reacting with the polyvinyl alcohol-based resin is preferably a compound having at least two functional groups reactive with the polyvinyl alcohol-based resin. For example, alkylenediamines having two alkylene groups and amino groups such as ethylenediamine, triethylenediamine and hexamethylenediamine; (Isocyanates such as 4-phenylmethane triisocyanate, isophorone diisocyanate and their ketoxime-blocked products or phenol-blocked products; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di- or triglycidyl ether, 1,6-hexane Epoxies such as diol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succindialdehyde, glutar dialdehydes such as dialdehyde, malein dialdehyde and phthaldialdehyde; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, condensates of benzoguanamine and formaldehyde; Salts and oxides of divalent metals such as sodium, potassium, magnesium, calcium, aluminum, iron, nickel, etc., or trivalent metal salts and oxides thereof Cross-linking agents capable of reacting with PVA-based resins are preferably amino-formaldehyde resins. The amino-formaldehyde resin is preferably a compound having a methylol group, the dialdehyde is preferably glyoxal, preferably a compound having a methylol group, more preferably methylolmelamine. By using a compound having a methylol group, a circularly polarizing plate having better optical properties can be obtained.

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

The easy-adhesion layer-forming composition may further contain any appropriate additive. Additives include, for example, antiblocking agents, dispersion stabilizers, thixotropic agents, antioxidants, ultraviolet absorbers, antifoaming agents, thickeners, dispersants, surfactants, catalysts, fillers, lubricants, antistatic agents, agents and the like.

The easy-adhesion layer 20 is typically formed by applying the easy-adhesion layer-forming composition to one surface of the retardation film 30 and drying it, as described above. When the retardation film is a stretched film, the easy-adhesion layer may be formed on the unstretched polycarbonate-based resin film and then stretched, or the easy-adhesion layer may be formed on the stretched polycarbonate-based resin film.

Any appropriate method can be adopted as a method for applying the easily adhesive layer-forming composition. Examples thereof include die coating, bar coating, roll coating, gravure coating, rod coating, slot orifice coating, curtain coating, fountain coating and the like. 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 within such a range, it is possible to provide a circularly polarizing plate having excellent color fastness (especially under high temperature and high humidity). The drying temperature is preferably 120° C. or lower, more preferably 100° C. or lower.

The thickness of the easily bonding 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, still more preferably 200 nm to 400 nm. By setting the thickness in such a range, the adhesion between the polarizer and the retardation film can be ensured. Furthermore, if there are scratches on the surface of the retardation film, the effect of filling the scratches can be exhibited.

D. Retardation Film The retardation film 30 contains a polycarbonate-based resin and functions as a λ/4 plate. A retardation film containing a polycarbonate-based resin has a problem that sufficient adhesion between the polarizer and the retardation film cannot be obtained. In the circularly polarizing plate of the present invention, the easy-adhesion layer is formed on one surface of the retardation film, and the polarizer is laminated on the surface on which the easy-adhesion layer is formed via an adhesive layer. and the retardation film can be secured.

The retardation film 30 typically has a slow axis. In one embodiment, the angle θ between the slow axis of the retardation film 30 and the absorption axis of the polarizer 10 is preferably 38° to 52°, more preferably 42° to 48°, More preferably, it is about 45°. If the angle θ is within such a range, a circularly polarizing plate having excellent circularly polarizing properties can be obtained.

The retardation film preferably exhibits a refractive index characteristic of nx>ny≧nz. A retardation film is typically provided to impart antireflection properties to the 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 even more preferably 110 nm to 170 nm. Here, "ny=nz" includes not only the case where ny and nz are completely equal but also the case where they are substantially equal. Therefore, it is possible that ny<nz to the extent that the effects of the present invention are not impaired.

The birefringence _Δnxy of the retardation film is, for example, 0.0025 or more, preferably 0.0028 or more. On the other hand, the upper limit of the birefringence _Δnxy is, for example, 0.0060, preferably 0.0050. By optimizing the birefringence in such a range, a retardation film that is thin and has desired optical properties can be obtained.

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, particularly preferably 0.9 to 1.3 . By satisfying such a relationship, when the obtained circularly polarizing plate is used in an image display device, a very excellent reflection hue can be achieved.

The retardation film may exhibit a reverse wavelength dispersion characteristic in which the retardation value increases according to the wavelength of the measurement light, or may exhibit a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It may well exhibit a flat wavelength dispersion characteristic in which the retardation value hardly changes even with the wavelength of the measurement light. The retardation film preferably exhibits reverse wavelength dispersion properties. In one embodiment, the retardation film exhibits reverse wavelength dispersion characteristics. In this case, the retardation film satisfies the relationship Re (450) < Re (550), Re (450) / Re (550) of the retardation film is preferably 0.8 or more and less than 1, more preferably It is 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection properties can be achieved. In another embodiment, the retardation film exhibits flat wavelength dispersion characteristics. In this case, Re (450) / Re (550) of the retardation film is preferably 0.99 to 1.03, Re (650) / Re (550) is preferably 0.98 to 1.02 . In this case, the retardation film may have a laminated structure. Specifically, a retardation film that functions as a λ / 2 plate and a retardation film that functions as a λ / 4 plate are arranged at a predetermined axis angle (for example, 50 ° to 70 °, preferably about 60 °). Therefore, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, and as a result, extremely excellent antireflection characteristics can be realized. By using such a retardation film, the antireflection effect can be exhibited more preferably.

The retardation film preferably has a water absorption of 3% or less, more preferably 2.5% or less, and still more preferably 2% or less. By satisfying such a water absorption rate, it is possible to suppress changes in display characteristics over time. Incidentally, the water absorption can be determined according to JIS K 7209.

The absolute value of the photoelastic coefficient of the retardation film is preferably 40×10 ⁻¹² Pa ⁻¹ or less, more preferably 35×10 ⁻¹² Pa ⁻¹ or less. When the photoelastic coefficient is in such a range, non-uniformity of retardation due to heat can be prevented. Also, it is possible to prevent the occurrence of deterioration in image quality.

The thickness of the retardation film is, for example, 70 μm or less, preferably 30 μm to 60 μm. With such a thickness, suitable mechanical strength can be imparted as a protective layer for a polarizer.

The retardation film contains a polycarbonate-based resin. Any appropriate polycarbonate-based resin can be used as the polycarbonate-based resin. Preferably, the polycarbonate-based resin comprises a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, an alicyclic diol, alicyclic dimethanol, di-, tri- or polyethylene glycol, and and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alkylene glycols or spiroglycols. 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. more preferably a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di-, tri- or polyethylene glycol. . The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds as necessary. The details of the polycarbonate resin that can be suitably used in the present invention are described, for example, in JP-A-2014-10291 and JP-A-2014-26266, and the description is incorporated herein by reference. be done.

（上記一般式（１）中、Ｒ^１～Ｒ^４はそれぞれ独立に、水素原子、置換若しくは無置換の炭素数１～２０のアルキル基、置換若しくは無置換の炭素数６～２０のシクロアルキル基、または、置換若しくは無置換の炭素数６～２０のアリール基を表し、Ｘは置換若しくは無置換の炭素数２～１０のアルキレン基、置換若しくは無置換の炭素数６～２０のシクロアルキレン基、または、置換若しくは無置換の炭素数６～２０のアリーレン基を表し、ｍ及びｎはそれぞれ独立に０～５の整数である。） In one embodiment, a polycarbonate-based resin containing a unit structure derived from a dihydroxy compound represented by the following general formula (1) can be used.

(In general formula (1) above, R ¹ to R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 6 to 20 carbon atoms, , or represents a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, X is a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, a substituted or unsubstituted cycloalkylene group having 6 to 20 carbon atoms, Alternatively, it represents a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, and 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, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9 - bis(4-hydroxy-3-ethylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-propylphenyl)fluorene, 9,9-bis(4-hydroxy-3-isopropylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-sec-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3- tert-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-cyclohexylphenyl)fluorene, 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-tert-butylphenyl)fluorene, 9 ,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4 -(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, 9,9-bis (4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene and the like.

In addition to the structural unit derived from the dihydroxy compound, the polycarbonate-based resin includes isosorbide, isomannide, isoidet, spiroglycol, dioxane glycol, diethylene glycol (DEG), triethylene glycol (TEG), polyethylene glycol (PEG), and bisphenols. may contain a structural unit derived from a dihydroxy compound such as

Details of polycarbonate resins containing structural units derived from dihydroxy compounds are described in, for example, Japanese Patent No. 5204200, Japanese Patent Application Laid-Open No. 2012-67300, Japanese Patent No. 3325560, WO2014/061677, and the like. The description of the patent document is incorporated herein by reference.

（上記一般式（２）および上記一般式（３）中、Ｒ_５およびＲ_６はそれぞれ独立に、直接結合、置換若しくは無置換の炭素数１～４のアルキレン基（好ましくは、主鎖上の炭素数が２～３であるアルキレン基）である。Ｒ_７は、直接結合、置換若しくは無置換の炭素数１～４のアルキレン基（好ましくは、主鎖上の炭素数が１～２であるアルキレン基）である。Ｒ_８～Ｒ_１３はそれぞれ独立に、水素原子、置換若しくは無置換の炭素数１～１０（好ましくは１～４、より好ましくは１～２）のアルキル基、置換若しくは無置換の炭素数４～１０（好ましくは４～８、より好ましくは４～７）のアリール基、置換若しくは無置換の炭素数１～１０（好ましくは１～４、より好ましくは１～２）のアシル基、置換若しくは無置換の炭素数１～１０（好ましくは１～４、より好ましくは１～２）のアルコキシ基、置換若しくは無置換の炭素数１～１０（好ましくは１～４、より好ましくは１～２）のアリールオキシ基、置換若しくは無置換の炭素数１～１０（好ましくは１～４、より好ましくは１～２）のアシルオキシ基、置換若しくは無置換のアミノ基、置換若しくは無置換の炭素数１～１０（好ましくは１～４）のビニル基、置換若しくは無置換の炭素数１～１０（好ましくは１～４）のエチニル基、置換基を有する硫黄原子、置換基を有するケイ素原子、ハロゲン原子、ニトロ基、またはシアノ基である。Ｒ_８～Ｒ_１３のうち隣接する少なくとも２つの基が互いに結合して環を形成していてもよい。） In one embodiment, polycarbonate-based resins containing oligofluorene structural units may be used. Polycarbonate resins containing oligofluorene structural units include, for example, resins containing structural units represented by the following general formula (2) and/or structural units represented by the following general formula (3).

(In general formulas (2) and (3) above, R ₅ and R ₆ are each independently a direct bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms (preferably, an alkylene group having 2 to 3 carbon atoms), and R ₇ is a direct bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms (preferably an alkylene group having 1 to 2 carbon atoms on the main chain). Each of R ₈ to R ₁₃ is independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), a substituted or unsubstituted A substituted or unsubstituted aryl group having 4 to 10 carbon atoms (preferably 4 to 8, more preferably 4 to 7) having 4 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2) having 1 to 10 carbon atoms acyl group, substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), substituted or unsubstituted 1 to 10 carbon atoms (preferably 1 to 4, more preferably is 1 to 2) aryloxy group, substituted or unsubstituted acyloxy group having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), substituted or unsubstituted amino group, substituted or unsubstituted A vinyl group having 1 to 10 carbon atoms (preferably 1 to 4), a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms (preferably 1 to 4), a sulfur atom having a substituent, a silicon having a substituent an atom, a halogen atom, a nitro group, or a cyano group, and at least two adjacent groups among R ₈ to R ₁₃ may bond together to form a ring.)

In one embodiment, the fluorene ring contained in the oligofluorene structural unit has a structure in which all of R ₈ to R ₁₃ are hydrogen atoms, or R ₈ and/or R ₁₃ are halogen atoms or acyl groups. , a nitro group, a cyano group, and a sulfo group, and R ₉ to R ₁₂ are hydrogen atoms.

Details of polycarbonate resins containing oligofluorene structural units are described, for example, in JP-A-2015-212816. The description of the patent document is incorporated herein by reference.

The glass transition temperature of the polycarbonate-based resin is preferably 110° C. or higher and 150° C. or lower, more preferably 120° C. or higher and 140° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to be poor, which may cause dimensional changes after film formation, and may lower the image quality of the resulting image display device. If the glass transition temperature is excessively high, the molding stability during film molding may deteriorate, and the transparency of the film may be impaired. The glass transition temperature is obtained according to JIS K 7121 (1987).

The molecular weight of the polycarbonate-based resin can be represented by the reduced viscosity. The reduced viscosity is measured using an Ubbelohde viscometer at a temperature of 20.0°C ± 0.1°C, using methylene chloride as a solvent, precisely adjusting the polycarbonate concentration to 0.6 g/dL. The lower limit of the reduced viscosity is usually preferably 0.30 dL/g, more preferably 0.35 dL/g or more. The upper limit of the reduced viscosity is usually preferably 1.20 dL/g, more preferably 1.00 dL/g, still more preferably 0.80 dL/g. If the reduced viscosity is less than the above lower limit, there may occur a problem that the mechanical strength of the molded product is reduced. On the other hand, if the reduced viscosity is higher than the above upper limit, there may be a problem that the fluidity during molding is lowered and the productivity and moldability are lowered.

A retardation film is obtained, for example, by stretching a film formed from the above-mentioned polycarbonate-based resin. Any appropriate molding method can be adopted as a method for forming a film from a polycarbonate-based resin. Specific examples include compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, cast coating method (e.g., casting method), calendar molding method, and heat press. law, etc. Extrusion or cast coating methods are preferred. This is because the smoothness of the resulting film can be enhanced and good optical uniformity can be obtained. Molding conditions can be appropriately set according to the composition and type of the resin used, properties desired for the retardation film, and the like. As described above, many film products of polycarbonate-based resins are commercially available, and the commercially available films may be subjected to the stretching treatment as they are.

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

Any suitable drawing method and drawing conditions (eg, drawing temperature, draw ratio, drawing direction) may be employed for the above-mentioned drawing. Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end shrinking, and fixed-end shrinking can be used singly or simultaneously or sequentially. As for the stretching direction, the stretching can be performed in various directions and dimensions such as the length direction, the width direction, the thickness direction, the oblique direction, and the like. The stretching temperature is preferably Tg-30°C to Tg+60°C, more preferably Tg-10°C to Tg+50°C, relative to the glass transition temperature (Tg) of the resin film.

By appropriately selecting the stretching method and stretching conditions, a retardation film having the desired optical properties (eg, refractive index properties, in-plane retardation, Nz coefficient) can be obtained.

In one embodiment, the retardation film is produced by uniaxially stretching or fixed-end uniaxially stretching a resin film. As a specific example of fixed-end uniaxial stretching, there is a method in which the resin film is stretched in the width direction (horizontal direction) while running in the longitudinal direction. The draw ratio is preferably 1.1 times to 3.5 times.

In another embodiment, the retardation film can be produced by continuously obliquely stretching a long resin film in the direction of the above angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of θ with respect to the longitudinal direction of the film (slow axis in the direction of angle θ) can be obtained. Roll-to-roll is possible, and the manufacturing process can be simplified. The angle θ may be the angle formed by the absorption axis of the polarizer and the slow axis of the retardation film in the circularly polarizing plate. The angle θ is, as described above, preferably 38° to 52°, more preferably 42° to 48°, and even more preferably about 45°.

E. Adhesive Layer The polarizer and the retardation film are attached via the adhesive layer formed on the easy-adhesion layer. The adhesive layer may consist of any suitable adhesive. The thickness of the adhesive layer is preferably 20 nm to 1000 nm, 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, 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 antireflection properties of the circularly polarizing plate can be maintained.

The adhesive preferably has transparency and optical isotropy. Any suitable adhesive may be employed. Specific examples include water-based adhesives, solvent-based adhesives, emulsion-based adhesives, non-solvent-based adhesives, active energy ray-curable adhesives, and heat-curable adhesives. Active energy ray-curable adhesives include electron beam-curable adhesives, ultraviolet-curable adhesives, and visible light-curable adhesives. Preferably, a thermosetting adhesive containing PVA-based resin or an ultraviolet curable adhesive is used.

Examples of PVA-based resins contained in thermosetting adhesives containing PVA-based resins include PVA resins and acetoacetyl group-containing PVA resins. An acetoacetyl group-containing PVA resin is preferred. This is because the adhesion between the polarizer and the protective film can be further improved, and the durability can be improved.

The acetoacetyl group-containing PVA-based resin can be obtained, for example, by reacting the PVA-based resin with diketene by any method. Specific examples include a method of adding diketene to a dispersion obtained by dispersing a PVA-based resin in a solvent such as acetic acid; a method of adding diketene to a solution of a PVA-based resin dissolved in a solvent such as dimethylformamide or dioxane. a method of bringing diketene gas or liquid diketene into direct contact with PVA-based resin;

The thermosetting adhesive containing the PVA-based resin may contain a cross-linking agent. Any appropriate cross-linking agent can be employed as the cross-linking agent. Preferably, it is a compound having at least two functional groups reactive with the PVA-based resin. As the compound having at least two functional groups reactive with the PVA-based resin, those mentioned as the cross-linking agent for the easy adhesion layer can be used.

The amount of the cross-linking agent to be blended can be appropriately set according to the type of the PVA-based resin. Typically, it is about 10 to 60 parts by weight, preferably 20 to 50 parts by weight, per 100 parts by weight of the PVA-based resin. It is because it can be excellent in adhesiveness. When the amount of the cross-linking agent is large, the reaction of the cross-linking agent proceeds in a short time, and the adhesive tends to gel. As a result, the usable time (pot life) as an adhesive is extremely shortened, and industrial use may become difficult.

The thermosetting adhesive containing the PVA-based resin may 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 electrostatically stabilized due to mutual repulsion of similar charges of the fine particles and have permanent stability. . By containing such a metal compound colloid, for example, an adhesive composition with excellent stability can be obtained even when the amount of the cross-linking agent is large.

The average particle size of the fine particles forming the metal compound colloid may be any appropriate value as long as it does not adversely affect optical properties such as polarization properties. It is preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm. This is because the fine particles can be uniformly dispersed in the adhesive layer, the adhesion can be secured, and the occurrence of knicks can be suppressed. In addition, a "knick defect" means light leakage.

Any appropriate compound can be adopted as the metal compound. Examples include metal oxides such as alumina, silica, zirconia, and titania; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, and calcium phosphate; and minerals such as celite, talc, clay, and kaolin. be done. As will be described later, positively charged metal compound colloids are preferably used in the present invention. Examples of the metal compound include alumina and titania, with alumina being particularly preferred.

The metal compound colloid typically exists in the form of a colloidal solution dispersed in a dispersion medium. Examples of dispersion media include water and alcohols. The solid content concentration in the colloidal solution is typically about 1% to 50% by weight, preferably 1% to 30% by weight. Colloidal solutions may contain acids such as nitric acid, hydrochloric acid, acetic acid, etc. as stabilizers.

The content of the metal compound colloid (solid content) 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 100 parts by weight based on 100 parts by weight of the polyvinyl alcohol resin. 175 parts by weight, particularly preferably 30 to 150 parts by weight. This is because it is possible to suppress the occurrence of knicks while ensuring adhesiveness.

A specific example of the ultraviolet curable adhesive is a (meth)acrylate adhesive. (Meth)acrylate means acrylate and/or methacrylate. The curable component in the (meth)acrylate adhesive includes, for example, a compound having a (meth)acryloyl group and a compound having a vinyl group. Preferred (meth)acryloyl group-containing compounds include N-substituted amide monomers represented by the following formula (4).
CH ₂ ═C(R ¹⁴ )—CONH _2-m —(X—O—R ¹⁵ ) _m (4)
Here, R ¹⁴ represents a hydrogen atom or a methyl group, X represents a -CH ₂ - group or a -CH ₂ CH ₂ - group, R ¹⁵ represents a -(CH ₂ ) _n -H group (where n is 0 , 1 or 2), and m represents 1 or 2.

The (meth)acrylate-based adhesive may further contain a monomer having two or more carbon-carbon double bonds, preferably a polyfunctional (meth)acrylate-based monomer, as a curable component. More preferably, monomers with two or more carbon-carbon double bonds are hydrophobic. In addition, the (meth)acrylate-based adhesive may contain various monofunctional (meth)acrylates having aromatic rings and hydroxyl groups, urethane (meth)acrylates, polyester (meth)acrylates, etc., as curable components. .

The (meth)acrylate-based adhesive may contain any suitable copolymer component.

The UV 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, relative to the total amount of the ultraviolet curable adhesive. , 0.1 to 3 parts by weight.

Various additives can be blended into the UV-curable adhesive as other optional components within a range that does not impair the objects and effects of the present invention. Such additives include various polymers or oligomers; polymerization inhibitors; polymerization initiation aids; leveling agents; wettability improvers; A dye etc. can be mentioned.

Another specific example of the active energy ray-curable adhesive is a photocationically curable adhesive mainly composed of an epoxy compound and a photoacid generator. Usable epoxy compounds include, for example, the compounds described in [0031]-[0085] of JP-A-2010-145537. Examples of the photoacid generator include compounds described in [0080]-[0095] of JP-A-2009-013316. The descriptions of these publications are incorporated herein by reference.

F. Protective Film The circularly polarizing plate of the present invention further includes any appropriate layer in addition to the polarizer, the easy-adhesion layer, and the retardation film. Examples include protective films. The protective film is formed of any suitable film that can be used as a protective film for polarizers. Specific examples of materials that are the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, and polysulfones. , polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based, and acetate-based transparent resins. Thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may also be used. In addition, for example, a glassy polymer such as a siloxane-based polymer can also be used. Further, polymer films described in JP-A-2001-343529 (WO01/37007) can also be used. Materials for this film include, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in a side chain. can be used, for example, a resin composition comprising an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile/styrene copolymer. The polymer film can be, for example, an extrudate of the resin composition.

The circularly 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, the protective film may be subjected to surface treatment such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment, if necessary.

Any appropriate thickness can be adopted as the thickness of the protective film. The thickness of the protective film is, for example, 10 μm to 100 μm, preferably 30 μm to 90 μm. In addition, when the surface treatment is given, the thickness of the protective film is the thickness including the thickness of the surface treatment layer.

G. Display Device The circularly polarizing plate of the present invention can be applied to any appropriate 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 polarizing plate arranged on the viewing side of the display element. The circularly polarizing plate is arranged so that the retardation layer faces the display element side.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. "Parts" and "%" in Examples and Comparative Examples are by weight unless otherwise specified.

(1) Thickness The thickness of the retardation film was measured using a dial gauge (manufactured by PEACOCK, product name: "DG-205 type pds-2").
(2) Refractive index Measured with an Abbe refractometer (DR-M2, manufactured by Atago). The measurement was performed in a 23° C. environment at a measurement wavelength of 589 nm.
(3) Initial adhesive strength (90° adhesive strength)
The circularly polarizing plates obtained in Examples and Comparative Examples were cut into a size of 200 mm parallel to the absorption axis direction of the polarizer and 20 mm in the orthogonal direction, and a cutter knife was used to make a cut between the retardation film and the polarizer. , the circularly polarizing plate was attached to a glass plate. Using a tensilon universal tester RTC manufactured by A&D Co., Ltd., the retardation film and the polarizer were peeled off at a peeling speed of 1000 mm / min in the direction of 90 degrees, and the peel strength was measured and taken as 90 ° adhesive strength. .
(4) Reflectance of circularly polarizing plate An adhesive (manufactured by Nitto Denko Co., Ltd., trade name: No. 7) was applied on the reflector so that the thickness after drying was 15 μm. The retardation film of the circularly polarizing plate and the reflector were bonded together. Further, a polarizing plate (manufactured by Nitto Denko Corporation, trade name “REGQS1298DUHC3”) was laminated on the retardation plate so that the angle formed by the slow axis of the retardation plate and the absorption axis of the polarizing plate was 45°. Then, the reflectance was measured using a spectrophotometer "CM-2600d" manufactured by Konica Minolta (SCI value).
(5) Presence or Absence of Peeling The circularly polarizing plates obtained in Examples and Comparative Examples were observed with an optical microscope to observe the presence or absence of peeling between the polarizer and the retardation film. Also, the circularly polarizing plates obtained in Examples and Comparative Examples were placed in an environment of 85° C. for 500 hours, and then the presence or absence of peeling was confirmed using an optical microscope (heating test). Similarly, the circularly polarizing plates obtained in Examples and Comparative Examples were placed 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 and humidification test). When peeling could not be confirmed, it was evaluated as ◯, and when there was peeling that could be visually confirmed, it was evaluated as x.
(6) Appearance (streak unevenness)
After placing the circularly polarizing plates obtained in Examples and Comparative Examples in an environment of 60° C. and 95% RH for 240 hours, the surfaces of the circularly polarizing plates were visually observed. When streaks were not visible in the darkroom, they were marked with ⊙, and when they were visible in the darkroom but not under normal operating conditions, they were marked with ◯.

(Production Example 1) Production of Retardation Film 1 Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 38.06 parts by weight (0.059 mol) and isosorbide (manufactured by Rocket Fleuret, 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 Kagaku Co., Ltd.) 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 charged into a reaction vessel. Then, the inside of the reactor was replaced with nitrogen under reduced pressure. The raw materials were dissolved under a nitrogen atmosphere with stirring at 150° C. for about 10 minutes. As the first step of the reaction, the temperature was raised to 220° C. over 30 minutes, and the reaction was carried out at normal pressure for 60 minutes. Subsequently, the pressure was reduced from normal pressure to 13.3 kPa over 90 minutes, and the pressure was maintained at 13.3 kPa for 30 minutes, and the generated phenol was discharged out of the reaction system. Next, as the second step of the reaction, the temperature of the heating medium was raised to 240° C. over 15 minutes while the pressure was reduced to 0.10 kPa or less over 15 minutes, and the generated phenol was discharged out of the reaction system. After reaching a predetermined stirring torque, the pressure was returned to normal pressure with nitrogen to stop the reaction, the polyester carbonate produced was extruded into water, and the strand was cut to obtain polycarbonate resin pellets. Next, a film was produced from the obtained polycarbonate-based resin pellets. The refractive index of the obtained film (unstretched) was 1.53.
The film is obliquely stretched to form 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 that time, the stretching direction was 45° with respect to the longitudinal direction of the film. The draw 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) Preparation of Retardation Film 2 To 81.98 parts by weight of isosorbide, 47.19 parts by weight of tricyclodecanedimethanol, 175.1 parts by weight of diphenyl carbonate, and 0.2 parts by weight of cesium carbonate as a catalyst. 0.979 parts by mass of an aqueous solution is put into a reaction vessel, and under a nitrogen atmosphere, as the first step of the reaction, the heating bath temperature is heated to 150 ° C., and the raw materials are added while stirring as necessary. Allow to dissolve (approximately 15 minutes).

Next, the pressure was changed from normal pressure to 13.3 kPa, and the generated phenol was discharged out of the reaction vessel while raising the heating bath temperature to 190° C. in 1 hour.
After holding the entire reaction vessel at 190°C for 15 minutes, as the second step, the pressure inside the reaction vessel was increased to 6.67 kPa, the heating tank temperature was raised to 230°C in 15 minutes, and the generated phenol was removed. It was pulled out of the reaction vessel. As the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and the pressure in the reaction vessel was made to reach 0.200 kPa or less in order to remove the generated phenol. After reaching a predetermined stirring torque, the reaction was terminated, and the produced reactant was extruded into water to obtain polycarbonate copolymer pellets.
The obtained pellets, a single screw extruder (manufactured by Isuzu Kakoki Co., Ltd., screw diameter 25 mm, cylinder set temperature: 220 ° C.), T die (width 200 mm, set temperature: 220 ° C.), chill roll (set temperature: 120 ~ 130° C.) and a film-forming apparatus equipped with a winder to obtain a film having a thickness of 100 μm. The refractive index of the obtained film (unstretched) was 1.51.
The resulting film was obliquely stretched to form 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 that time, the stretching direction was 45° with respect to the longitudinal direction of the film. The draw ratio was adjusted to 2 to 3 times so that the obtained retardation film exhibited a retardation of λ/4.

(Production Example 3) Preparation of polarizer A polymer film (manufactured by Kuraray Co., Ltd., trade name “VF-PE-A#3000”) having a thickness of 30 μm and mainly composed of a polyvinyl alcohol resin was prepared by the following (1) to The film was immersed in five baths under the conditions of (5) while tension was applied in the longitudinal direction of the film, and then stretched so that the final draw ratio was 6.2 times the original length of the film. This stretched film was dried for 1 minute in an air circulation drying oven at 40 degrees to produce a polarizer.
<Condition>
(1) Swelling bath: Pure water at 30°C.
(2) Dyeing bath: A 30°C aqueous solution containing 0.035 parts by weight of iodine and 0.2 parts by weight of potassium iodide per 100 parts by weight of water.
(3) First cross-linking bath: 40° C. aqueous solution containing 3% by weight of potassium iodide and 3% by weight of boric acid.
(4) Second cross-linking bath: 60° C. aqueous solution containing 5% by weight of potassium iodide and 4% by weight of boric acid.
(5) Washing bath: 25° C. aqueous solution containing 2.6% by weight of potassium iodide.

[Example 1]
(Preparation of easy-adhesion layer-forming composition 1)
Add and mix 5 parts by weight of a cross-linking agent (manufactured by DIC, product name: Watersol S695) to 100 parts by weight of urethane resin (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Superflex 210) to form an easy-adhesion layer. A composition was prepared.
(Preparation of adhesive composition 1)
50 parts by weight of methylol melamine was dissolved in pure water with respect to 100 parts by weight of a polyvinyl alcohol resin having an acetoacetyl group (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%). , Prepare an aqueous solution with a solid content concentration of 3.7% by weight, and 18 parts by weight of an aqueous solution containing positively charged alumina colloid (average particle diameter 15 nm) at a solids concentration of 10% by weight per 100 parts by weight of this aqueous solution. was prepared by adding

The easy-adhesion layer-forming composition was applied to one surface of the retardation film 1 to form an easy-adhesion layer having a thickness of 100 nm.
In addition, a TAC film (TAC film (Konica Minolta A polarizer was attached to a surface of a polarizer (trade name: KC2UA manufactured by Co., Ltd., one surface of which was hard-coated) that was not hard-coated.
Next, the adhesive composition 1 is applied to the easy adhesion layer so that the thickness after drying is 0.1 μm, and the polarizer and the retardation film of the laminate of the polarizer and the TAC film are laminated, A circularly polarizing plate was obtained. The slow axis of the retardation film and the absorption axis of the polarizer were attached so as to form an angle of 45°. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[Example 2]
A circularly polarizing plate was produced in the same manner as in Example 1, except that 15 parts by weight of the cross-linking agent was added to the easy-adhesion layer-forming composition. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[Example 3]
A circularly polarizing plate was obtained in the same manner as in Example 1, except that an oxazoline group-containing water-soluble polymer (manufactured by Nippon Shokubai Co., Ltd., trade name: Epocross WS700) was used as the cross-linking agent contained in the composition for forming an easily adhesive layer. . Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[Example 4]
A circularly polarizing plate was produced in the same manner as in Example 3, except that the amount of the cross-linking agent added to the easy-adhesion layer-forming composition was changed to 15 parts by weight. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[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. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[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. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[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. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[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. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[Example 9]
(Preparation of adhesive composition 2)
Active energy ray curing components (10 parts by weight of hydroxyethylacrylamide, 30 parts by weight of acryloylmorpholine, and 54.5 parts by weight of 1,9-nonanediol diacrylate), and a foam inhibitor (polyorganosiloxane (manufactured by BYK Chemie Japan) , trade name: BYK-UV 3570)) 0.50 parts by weight, and as polymerization initiators, 3 parts by weight of IRGACURE 907 (manufactured by BASF) and 2 parts by weight of KAYACURE DETX-S (manufactured by Nippon Kayaku Co., Ltd.). , Adhesive Composition 2 was prepared.
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. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

[Example 10]
A circularly polarizing plate was produced in the same manner as in Example 4, except that the adhesive composition 2 was used to form an adhesive layer having a thickness of 0.50 μm. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

(Comparative example 1)
A circularly polarizing plate was produced in the same manner as in Example 1, except that no cross-linking agent was added to the easily adhesive layer-forming composition. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

(Comparative example 2)
In the same manner as in Example 1, except that a silane coupling agent (manufactured by Shin-Etsu Silicone Co., Ltd., trade name: KBM603) was used instead of the easy-adhesion layer-forming composition 1 to form an easy-adhesion layer with a thickness of 50 nm. A plate was made. Table 1 shows the evaluation results of the obtained circularly polarizing plate.

(Comparative Example 3)
A circularly polarizing plate was produced in the same manner as in Example 5, except that no cross-linking agent was added to the easy-adhesion layer-forming composition. Table 1 shows the evaluation results of the obtained circularly polarizing plate.
In addition, circularly polarizing plates were produced by changing the thickness of the easy-adhesion layer to 200 nm or 400 nm, respectively, and the obtained circularly polarizing plates were similarly evaluated. Table 1 shows the results.

(Comparative Example 4)
In the same manner as in Example 5, except that a silane coupling agent (manufactured by Shin-Etsu Silicone Co., Ltd., trade name: KBM603) was used instead of the easy-adhesion layer-forming composition 1 to form an easy-adhesion layer with a thickness of 50 nm. A plate was made. Table 1 shows the evaluation results of the obtained circularly polarizing plate.

(Comparative Example 5)
Instead of the easy-adhesion layer-forming composition 1, a modified polyolefin resin (manufactured by Unitika Ltd., trade name "Arrow Base SE-1030N"), an aqueous solution of a polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER Z200"), and an easy-adhesion layer-forming composition mixed with pure water to obtain a thickness A circularly polarizing plate was produced in the same manner as in Example 5, except that an easy-adhesion layer with a thickness of 500 nm was formed. Table 1 shows the evaluation results of the obtained circularly polarizing plate.

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

[evaluation]
As is clear from Table 1, the circularly polarizing plate of the present invention ensured sufficient adhesion between the polarizer and the retardation film. These circularly polarizing plates maintained sufficient adhesion even when placed under heating conditions and heating and humidifying conditions. Furthermore, the excellent antireflection properties of the circularly polarizing plate were maintained. In particular, in Examples 1 to 4 using a retardation film having a reverse dispersion property, the antireflection property of the circularly polarizing plate was more exhibited.

The circularly polarizing plate of the present invention is suitably used for display devices such as liquid crystal display devices and organic EL display devices. The circularly polarizing plate of the present invention can be suitably used regardless of the type of surface treatment.

REFERENCE SIGNS LIST 10 polarizer 20 easy adhesion layer 30 retardation film 40 adhesive layer 100 circularly polarizing plate

Claims (6)

a polarizer;
an easy-adhesion layer containing a urethane-based resin having a carboxyl group and a cross-linking agent;
A retardation film that contains a polycarbonate resin, functions as a λ / 4 plate, and satisfies the relationship Re (450) < Re (550) in this order,
The composition forming the easy adhesion layer contains 5 to 15 parts by weight of the cross-linking agent with respect to 100 parts by weight of the urethane resin having the carboxyl group,
The thickness of the easy-adhesion layer is 200 nm to 400 nm,
The retardation film is a stretched film of a film formed from a polycarbonate-based resin,
A circularly polarizing plate, wherein the refractive index difference between the retardation film and the easy-adhesion layer is 0.01 or less. 2. The circularly 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. 3. The circularly polarizing plate according to claim 1, wherein a 90[deg. ] adhesive strength between said retardation film and said easy-adhesion layer is 1.0 N/15 mm or more. 4. The circularly polarizing plate according to claim 1, wherein the 90[ deg .] adhesive force between said polarizer and said easy-adhesion layer is 1.0 N/15 mm or more. 5. The circularly polarizing plate according to claim 1 , wherein the 90[deg.] adhesive force between said polarizer and said easy-adhesion layer is 1.0 N/15 mm or more after being placed at 85[deg.] C. for 500 hours. 6. The 90° adhesive force between the polarizer and the easy-adhesion layer after being placed under conditions of 60° C. and 95% RH for 240 hours is 0.5 N/15 mm or more, according to any one of claims 1 to 5 . circular polarizer.

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