KR102435572B1 - Retardation film, polarizing plate comprising the same and display apparatus comprising the same - Google Patents

Abstract

A retardation film comprising a phenoxy resin having a repeating unit consisting of a unit of Formula 1 and a unit of Formula 2 as a base resin, wherein the deviation of the in-plane retardation of Formulas 1 and 2 is 0 nm to 5 nm, respectively, comprising the same A polarizing plate and a display device including the same are provided.

Description

Retardation film, a polarizing plate including the same, and a display device including the same

The present invention relates to a retardation film, a polarizing plate including the same, and a display device including the same.

In display devices such as a liquid crystal display (LCD) or an organic light emitting diode (OLED), the retardation film is used for the purpose of improving a viewing angle, improving display quality, or preventing reflection. The retardation film may be divided into those having forward wavelength dispersion, flat wavelength dispersion, and reverse wavelength dispersion according to wavelength dispersion characteristics. The retardation film having reverse wavelength dispersion refers to a retardation film having a characteristic that a retardation value generated as the wavelength of incident light increases.

In recent years, as a new display device, a self-luminous display device such as an organic electroluminescent display device is attracting attention. In an organic electroluminescent display device, since a reflector such as an aluminum plate is provided on the back side of the display in order to increase light extraction efficiency, external light incident on the display is reflected by the reflector, thereby reducing the contrast of the image. . In order to solve this problem, a method of using a circularly polarizing plate is known for the purpose of preventing side surface light reflection.

The circularly polarizing plate should include a retardation film having reverse wavelength dispersion. The retardation film having reverse wavelength dispersion is prepared by uniaxially, biaxially, or obliquely stretching an unstretched film. However, in the process of stretching the unstretched film of the same material, non-uniformity in MD (machine direction) and/or TD (transverse direction) in-plane retardation of the unstretched film may occur. The non-uniformity of the in-plane retardation not only impairs the uniformity of screen quality, but also requires the use of a retardation film having a relatively large area, which is not economical.

Background art of the present invention is disclosed in Korean Patent Laid-Open No. 10-2016-0006817 and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a retardation film capable of minimizing the deviation of in-plane retardation in both MD (machine direction) and TD (transverse direction) directions.

Another object of the present invention is to provide a retardation film having reverse wavelength dispersion and realizing in-plane retardation Re 100nm to 200nm at a wavelength of 550nm.

Another object of the present invention is to provide a retardation film having a low haze and excellent optical transparency.

Another object of the present invention is to provide a retardation film capable of lowering the difference in visibility from left to right.

Another object of the present invention is to provide a polarizing plate and a display device including the retardation film of the present invention.

The retardation film of the present invention includes a phenoxy resin having a repeating unit consisting of a unit of Chemical Formula 1 and a unit of Chemical Formula 2 as a base resin, and the retardation film has a deviation of the in-plane retardation of the following Formulas 1 and 2 can be 0 nm to 5 nm, respectively:

[Formula 1]

(In Formula 1, R ¹ , R ² are each independently an alkyl group having 1 to 5 carbon atoms, n and m are each independently an integer of 0 to 4, R ³ , R ⁴ are each independently 1 to 5 carbon atoms of an alkylene group).

[Formula 2]

(In Formula 2, A is -C(R ¹ R ² )-, R ¹ , R ² are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms, or R ¹ , R ² are connected to each other and have carbon atoms to form an alicyclic group having 5 to 7 carbon atoms).

[Equation 1]

Deviation of in-plane phase difference on the MD side = Re(max) - Re(min)

(In Equation 1, 5 points are marked at intervals of 0.3 cm in the MD direction for a rectangular specimen of 3 cm in the MD direction and 2 cm in the TD direction among the retardation films, and the in-plane retardation at a wavelength of 550 nm is measured and measured at the points. Among the in-plane phase differences, the maximum value is called Re(max) (unit: nm), and the minimum value is called Re(min) (unit: nm)),

[Equation 2]

Deviation of in-plane phase difference on the TD side = Re(max) - Re(min)

(In Equation 2, 5 points are marked with an interval of 0.3 cm in the TD direction for a rectangular specimen of 3 cm in the MD direction and 2 cm in the TD direction among the retardation films, and the in-plane retardation at a wavelength of 550 nm is measured and measured at the points. Among the in-plane phase differences, the maximum value is called Re(max) (unit: nm), and the minimum value is called Re(min) (unit: nm)).

The polarizing plate of the present invention may include a polarizing film and the retardation film of the present invention formed on one surface of the polarizing film.

The display device of the present invention may include the retardation film of the present invention or the polarizing plate of the present invention.

The present invention provides a retardation film capable of minimizing the deviation of the in-plane retardation in both MD and TD directions.

The present invention provides a retardation film having reverse wavelength dispersion and capable of realizing an in-plane retardation Re 100 nm to 200 nm at a wavelength of 550 nm.

The present invention provides a retardation film having a low haze and excellent optical transparency.

The present invention provides a retardation film having a small difference in visibility from left to right.

The present invention provides a polarizing plate and a display device including the retardation film of the present invention.

It will be described in detail so that a person of ordinary skill in the art can easily carry out the present invention according to the accompanying embodiments. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention, parts not related to the description are omitted.

In the present specification, the "in-plane retardation (Re)" is represented by the following formula A, the "thickness direction retardation (Rth)" is represented by the following formula B, and "the degree of biaxiality (NZ)" can be represented by the following formula C have:

<Formula A>

Re = (nx - ny) x d

<Formula B>

Rth = ((nx + ny)/2 - nz) x d

<Formula C>

NZ = (nx - nz)/(nx - ny)

(In Formulas A to C, nx, ny, and nz are refractive indices of the retardation film in the slow axis direction, fast axis direction, and thickness direction, respectively, at the measurement wavelength, and d is the thickness of the retardation film (unit: nm)). The "measurement wavelength" may be a wavelength of 450 nm, 550 nm or 650 nm.

In this specification, 'nx', 'ny', and 'nz' refer to refractive indices in a slow axis direction, a fast axis direction, and a thickness direction of the corresponding retardation film at the measurement wavelength.

The inventors of the present invention include a phenoxy resin having a repeating unit composed of a unit of Formula 1 and a unit of Formula 2 as a base resin of the retardation film, thereby stretching an unstretched film including the base resin at a predetermined draw ratio. However, it was confirmed that the deviation of the in-plane phase difference in both MD and TD directions was lowered while exhibiting reverse wavelength dispersion, and the present invention was completed.

Hereinafter, a retardation film according to an embodiment of the present invention will be described.

The retardation film may have a deviation of the in-plane retardation of Equation 1 and Equation 2, respectively, of 0 nm to 5 nm: In the above range, the availability of the retardation film can be increased by uniform in-plane retardation even in a wide range of retardation films, and, in particular, a polarizing plate When applied to a polarizer used in a large-screen display device, the screen quality can be improved:

[Equation 1]

Deviation of in-plane phase difference on the MD side = Re(max) - Re(min)

(In Equation 1, 5 points are marked at intervals of 0.3 cm in the MD direction for a rectangular specimen of 3 cm in the MD direction and 2 cm in the TD direction among the retardation films, and the in-plane retardation at a wavelength of 550 nm is measured and measured at the points. Among the in-plane phase differences, the maximum value is called Re(max) (unit: nm), and the minimum value is called Re(min) (unit: nm)),

[Equation 2]

Deviation of in-plane phase difference on the TD side = Re(max) - Re(min)

(In Equation 2, 5 points are marked with an interval of 0.3 cm in the TD direction for a rectangular specimen of 3 cm in the MD direction and 2 cm in the TD direction among the retardation films, and the in-plane retardation at a wavelength of 550 nm is measured and measured at the points. Among the in-plane phase differences, the maximum value is called Re(max) (unit: nm), and the minimum value is called Re(min) (unit: nm)).

The deviation of the in-plane phase difference of Equation 1 and Equation 2 is measured multiple times and obtained as an average value. The deviation of the in-plane phase difference of Equation 1 and Equation 2 is measured with reference to the experimental examples described below.

The retardation film contains a phenoxy resin having a repeating unit consisting of a unit of Formula 1 and a unit of Formula 2 as a base resin, so that the deviation of the in-plane retardation of Formulas 1 and 2 can easily reach 0 nm to 5 nm have:

[Formula 1]

(In Formula 1, R ¹ , R ² are each independently an alkyl group having 1 to 5 carbon atoms, n and m are each independently an integer of 0 to 4, R ³ , R ⁴ are each independently 1 to 5 carbon atoms of an alkylene group).

[Formula 2]

(In Formula 2, A is -C(R ¹ R ² )-, R ¹ , R ² are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms, or R ¹ , R ² are connected to each other and have carbon atoms to form an alicyclic group having 5 to 7 carbon atoms).

Preferably, in Formula 2, A is *-CH ₂ -*, *-C(CH ₃ ) ₂ -* or *-C(C ₅ H ₁₀ )-* (* is a connection site to the carbon of the phenyl group) this can be

The retardation film containing a phenoxy resin prepared by using an epoxy compound having a polycyclic aromatic group such as a naphthyl group or an anthracene group instead of a phenyl group in the unit of Formula 1 has weak reverse wavelength characteristics, so it can produce desired retardation and reverse wavelength dispersion characteristics. It is not possible, and in particular, the following Equation 4 cannot be implemented.

In one embodiment, the phenoxy resin comprises 50:50 to 90:10, preferably 50:50 to 90:10 of the unit of Formula 1: the unit of Formula 2, among 100 mol% of the total moles of the unit of Formula 1 and the unit of Formula 2 It may be included in a mole ratio of 60:40 to 90:10. In the mole ratio range, the deviation of the in-plane retardation of Equations 1 and 2 can reach 0 nm to 5 nm, and the glass transition temperature range of the retardation film of the present invention can be easily reached, so that the film is broken even by stretching or The film does not break and the target retardation can be reached.

In one embodiment, the phenoxy resin may include a unit of Formula 3 below as the repeating unit:

<Formula 3>

(In Formula 3, R ¹ , R ² , R ³ , R ⁴ , n, and m are as defined in Formula 1, and A is as defined in Formula 2).

The phenoxy resin contains 50:50 to 90:10, preferably 60:40 to 90: a bifunctional bis(phenyl glycidyl ether) compound having a fluorene skeleton and a bisphenol-based compound in 100 mol% of the total moles: It can be prepared by reacting in a mole ratio of 10. In the mole ratio range, the deviation of the in-plane retardation of Equations 1 and 2 can reach 0 nm to 5 nm, and the glass transition temperature range of the retardation film of the present invention can be easily reached, so that the film is broken even by stretching or The film does not break and the target retardation can be reached.

The bifunctional bis (phenylglycidyl ether) compound having a fluorene skeleton may include a bifunctional epoxy compound having a 9,9-bis condensed phenyl fluorene skeleton.

The bifunctional bis(phenylglycidyl ether) compound having a fluorene skeleton may not have a polycyclic aromatic group such as a naphthyl group or an anthracene group (eg, a polycyclic aromatic group having 10 to 30 carbon atoms). Retardation film comprising a phenoxy resin prepared by using an epoxy compound having a polycyclic aromatic group such as a naphthyl group or an anthracene group instead of a phenyl group in a bifunctional bis(phenylglycidyl ether) compound having a fluorene skeleton has a reverse wavelength Since the characteristics are weak, desired phase difference and reverse wavelength dispersion characteristics cannot be obtained, and in particular, Equation 4 below cannot be implemented.

For example, the bifunctional bis(phenylglycidyl ether) compound having a fluorene skeleton may include a compound represented by the following formula (4):

<Formula 4>

(In Formula 4, R ¹ , R ² are each independently an alkyl group having 1 to 5 carbon atoms, n and m are each independently an integer of 0 to 4, R ³ , R ⁴ are each independently 1 to 5 carbon atoms of an alkylene group). Preferably, in Formula 4, n and m are 0. Preferably, in Formula 4, R ³ and R ⁴ are each independently a methylene group.

The bisphenol-based compound may include at least one selected from the following Chemical Formula 5-1, the following Chemical Formula 5-2, and the following Chemical Formula 5-3.

<Formula 5-1>

<Formula 5-2>

<Formula 5-3>

The reaction of forming a phenoxy resin by reacting a bifunctional bis(phenyl glycidyl ether) compound having a fluorene skeleton with a bisphenol-based compound may be performed according to a conventional method known to those skilled in the art. For example, the reaction between a bifunctional bis(phenylglycidyl ether) compound having a fluorene skeleton and a bisphenol-based compound may be performed in a warming reaction. When carried out under heating, the reaction may be carried out at 50 °C to 300 °C, for example, 100 °C to 250 °C, 150 °C to 200 °C. The reaction time may be 30 minutes to 24 hours, preferably 1 hour to 18 hours, more preferably 2 hours to 12 hours. For example, the reaction of a bifunctional bis(phenyl glycidyl ether) compound having a fluorene skeleton and a bisphenol-based compound may be performed in the presence of a catalyst. The catalyst is not particularly limited, and hydroxides (alkali metal hydroxide salts such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxide salts), amines (aliphatic amines, aromatic amines, heterocyclic amines, etc.), quaternary ammonium salts, phosphonium salts and the like. For example, the reaction of a bifunctional bis(phenylglycidyl ether) compound having a fluorene skeleton and a bisphenol-based compound may be performed in the presence of a solvent. The solvent is not particularly limited, and may be hydrocarbons, alcohols, ethers, ketones, esters, amides, nitriles, sulfoxides, and the like.

The reaction of a bifunctional bis(phenylglycidyl ether) compound having a fluorene skeleton and a bisphenol-based compound may increase the molecular weight of the phenoxy resin by aging at a predetermined temperature after forming the phenoxy resin. . For example, the aging may be performed at 50 °C to 300 °C, for example 100 °C to 250 °C, 150 °C to 200 °C. For example, the aging may be 30 minutes to 24 hours, preferably 1 hour to 18 hours, more preferably 2 hours to 12 hours.

The weight average molecular weight of the phenoxy resin may be 50,000 to 100,000, preferably 60,000 to 80,000. Within the above range, there may be no breakage during film formation and stretching process during extrusion and there may be an effect of improving retardation.

The glass transition temperature of the phenoxy resin may be 115°C to 150°C, preferably 125°C to 145°C. In the above range, even if the unstretched film including the phenoxy resin as the base resin is stretched, the film does not break or break, so that the retardation of the present invention can be sufficiently secured.

The retardation film of the present invention may include a stretched film of an unstretched film including a phenoxy resin formed by reacting a bifunctional bis(phenylglycidyl ether) compound having a fluorene skeleton with a bisphenol-based compound. The retardation film may have a glass transition temperature of 115°C to 150°C, preferably 125°C to 145°C. In the above range, the change in retardation due to the shrinkage of the retardation film is minimized even at 110° C. or higher, and there may be an effect of having durability reliability.

The retardation film may have an in-plane retardation Re at a wavelength of 550 nm from 100 nm to 200 nm, for example from 100 nm to 150 nm, for example, 1/4 retardation. In the above range, when used in a polarizing plate for a light emitting display device, the screen quality can be improved by lowering the lateral reflectance for external light.

The retardation film can implement reverse wavelength dispersion by satisfying the following Equations 3 and 4: The retardation film exhibits reverse wavelength dispersion, so that when used in a polarizing plate for a light emitting display device, the lateral reflectance for external light is lowered to improve the screen quality. can:

[Equation 3]

0.6 ≤ Re(450)/Re(550) ≤ 0.9

[Equation 4]

1.0 < Re(650)/Re(550) ≤ 1.3

(In Equation 3 and Equation 4, Re (450) is the in-plane retardation (unit: nm) at the wavelength of the retardation film at 450 nm, Re (550) is the in-plane retardation at the wavelength of the retardation film at 550 nm (unit: nm), Re ( 650) is the in-plane retardation (unit: nm) at a wavelength of 650 nm of the retardation film.

For example, the retardation film may have a Re(450)/Re(550) (ratio of Re(450) to Re(550)) of Equation 3 of 0.75 to 0.9, preferably 0.8 to 0.87. For example, the retardation film may have a Re(650)/Re(550) (ratio of Re(650) to Re(550)) in Equation 4 of 1.02 to 1.2, preferably 1.05 to 1.2.

For example, the retardation film may have Re (450) of 105 nm to 130 nm, preferably 110 nm to 128 nm, 110 nm to 127 nm, and 110 nm to 125 nm. In the above range, there may be an anti-reflection effect. For example, the retardation film may have Re (650) of 140 nm to 170 nm, 143 nm to 170 nm, and preferably 143 nm to 166 nm. In the above range, there may be an anti-reflection effect.

The retardation film may have a haze of 0% to 3%, preferably 0% to 1%. Within the above range, optical transparency can be increased when used in a polarizing plate for a light emitting display device, and even when laminated with a positive C layer, it can be used in a polarizing plate.

The retardation film may have a thickness of more than 0 μm and 100 μm or less, for example, 30 μm to 80 μm, and 40 μm to 60 μm. Within the above range, it may be used in a polarizing plate for a light emitting display device.

The retardation film may have a thickness direction retardation Rth of 30 nm to 100 nm at a wavelength of 550 nm, for example, 40 nm to 100 nm, or 40 nm to 80 nm. In the above range, there may be an effect of minimizing side reflection by being laminated with the positive C film.

The retardation film may have a degree of biaxiality NZ of 0.95 to 1.05, for example, 0.96 to 1.03, at a wavelength of 550 nm. In the above range, there is an effect of having the reverse wavelength characteristic in the entire visible light region, and in particular, the difference in compensation characteristics for each wavelength can be removed, thereby maximizing the effect.

The retardation film may have a refractive index of 1.45 to 1.55, preferably 1.49 to 1.52. In the above range, there may be an effect of phase difference expression.

The retardation film may have nx of 1.51 to 1.52, ny of 1.50 to 1.51, and nz of 1.505 to 1.515 at a wavelength of 550 nm. In the above range, there may be a reverse wavelength characteristic and a circular polarization effect.

In one embodiment, the retardation film may be a non-epoxy-based retardation film having no epoxy group.

The retardation film may be prepared from a composition for a retardation film including the base resin. In the composition for retardation film, the base resin may be included in an amount of 90 parts by weight to 100 parts by weight, preferably 95 parts by weight to 100 parts by weight, based on the solid content. In the above range, even if the unstretched film is stretched, there is no film breakage and reverse wavelength dispersion and in-plane retardation can be implemented.

The composition for retardation film may further include an additive, if necessary, in addition to the base resin. The additives include fillers, reinforcing agents, colorants (dyes or pigments), conductive agents, flame retardants, plasticizers, lubricants, stabilizers (heat stabilizers or antioxidants), curing agents, curing accelerators, mold release agents, antistatic agents, flow regulators, leveling agents, dispersants, It may include, but is not limited to, one or more of an antifoaming agent and a surface modifier. Additives may be included alone or in mixture of two or more.

In one embodiment, the retardation film may further include rod-shaped nanoparticles. The rod-shaped nanoparticles are elongated rod-shaped nanoparticles and refer to nanoparticles having a long axis and a short axis. The rod-shaped nanoparticles have a higher refractive index in the thickness direction than in the plane direction, so when the rod-shaped nanoparticles are included in the film and then stretched, the rod-shaped nanoparticles are arranged in the stretching direction to increase the refractive index in the thickness direction, thereby stably realizing the phase difference of the present invention. and increase the strength of the film. The rod-shaped nanoparticles may have a refractive index ratio of a refractive index in a major axis direction: a refractive index in a minor axis direction in a range of 1:1.2 to 1:1.7. In the above range, the retardation of the present invention may be better exhibited when the film is stretched. The rod-shaped nanoparticles may have a length aspect ratio of 1.5:1 to 3:1, preferably 2:1 to 3:1. In the above range, the retardation of the present invention may be exhibited when the film is stretched, the total light transmittance of the film may be increased, and may not be crushed when mixed with the resin. The aspect ratio means the ratio of the long axis, ie, length, of the rod-shaped nanoparticles to the diameter of the short axis, ie, cross-section, of the rod-shaped nanoparticles. The rod-shaped nanoparticles may have a short axis of 5 nm to 50 nm, preferably 10 nm to 30 nm, and a long axis of 30 nm to 150 μm. Within the above range, the strength of the film can be increased, and desired birefringence can be achieved.

The rod-shaped nanoparticles exhibit negative optical anisotropy, and may include, for example, at least one of strontium carbonate (SrCO ₃ ), calcium carbonate, magnesium carbonate, zirconium carbonate, cobalt carbonate, and manganese carbonate, preferably in the present invention. Strontium carbonate can be used for the aromatic vinyl-based monomer, acid anhydride-based monomer and comonomer. The rod-shaped nanoparticles may be used that are not surface-treated, but those that are surface-treated with a titanate compound such as titanium may be used.

The rod-shaped nanoparticles may be included in an amount of 1 wt% to 15 wt%, preferably 2 wt% to 10 wt% of the retardation film. In the above range, the effect of the film of the present invention can be obtained by increasing the refractive index in the thickness direction of the retardation film.

The retardation film may be prepared by preparing an unstretched film by forming or molding the composition for retardation film using a conventional film-forming method, casting method, melt extrusion method, calendering method, etc., and stretching the prepared unstretched film. . The stretching may be uniaxial stretching or biaxial stretching, preferably biaxial stretching. Also, the stretching may be performed by diagonal stretching. Uniaxial stretching includes fixed width uniaxial stretching. The draw ratio may be 1.5 times to 4.5 times the MD draw ratio and/or 1.5 times to 4.5 times the TD draw ratio based on uniaxial stretching. Biaxial stretching may be 1.1 times to 1.5 times in TD after stretching 1.5 times to 4.5 times in the MD direction. The stretching temperature may be 125°C to 160°C, preferably 135°C to 155°C. In the above range, there may be an effect of minimizing retardation and in-plane deviation due to stretching. Stretching is to apply a stretching treatment to an unstretched film after film formation or molding, and the stretching method is not particularly limited, and wet stretching or dry stretching, a tenter method, a tube method, and the like can be employed.

Hereinafter, the polarizing plate of this invention is demonstrated.

The polarizing plate may include a polarizing film and the retardation film of the present invention formed on one surface of the polarizing film. The polarizing plate can improve screen quality by lowering the lateral reflectance for external light by being used in a light emitting display device.

In one embodiment, the polarizing plate may include a polarizing film and the retardation film of the present invention formed on a lower surface of the polarizing film. By further forming an adhesive film on the lower surface of the retardation film, a polarizing plate may be laminated on a panel for a light emitting display device.

In one embodiment, the polarizing film may be a polarizer. Specifically, the polarizer may include a polyvinyl alcohol-based polarizer manufactured by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film. The polarizer may have a thickness of 5 μm to 40 μm. Within the above range, it can be used in a display device.

In another embodiment, the polarizing film may include a polarizer and a protective layer formed on at least one surface of the polarizer. The protective layer may protect the polarizer to increase reliability of the polarizer and increase mechanical strength of the polarizer.

The protective layer may include one or more of an optically clear, protective film or protective coating layer. The protective film is a cellulose ester-based resin containing triacetyl cellulose (TAC), etc., a cyclic polyolefin-based resin containing amorphous cyclic polyolefin (COP), etc., a polycarbonate-based resin, polyethylene terephthalate (PET), etc. Poly(meth)acrylate-based resins including polyester-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethyl methacrylate resins, and the like It may include a film formed of at least one of a resin, polyvinyl alcohol-based resin, polyvinyl chloride-based resin, and polyvinylidene chloride-based resin, but is not limited thereto. The protective coating layer may be formed of an active energy ray-curable resin composition including an active energy ray-curable compound and a polymerization initiator. The active energy ray-curable compound may include at least one of a cationically polymerizable curable compound, a radical polymerizable curable compound, a urethane resin, and a silicone-based resin.

A functional coating layer may be additionally formed on the other surface of the polarizing film. The functional coating layer may include, but is not limited to, at least one of a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low reflection layer, and an ultra-low reflection layer.

An angle between the absorption axis (MD of the polarizer) of the polarizing film and the optical axis of the retardation film may be 43° to 47°. In the above range, there may be a reflectance reduction effect.

The retardation film may be directly laminated on the polarizing film. That is, the optical film may be laminated in contact with the polarizing film without an adhesive layer, an adhesive layer, or an adhesive layer.

The retardation film may be laminated on the polarizing film by an adhesive layer, an adhesive layer, or an adhesive layer. The pressure-sensitive adhesive layer, the adhesive layer, or the pressure-sensitive adhesive layer may be formed of a conventional pressure-sensitive adhesive known to those skilled in the art, but is not limited thereto.

In another embodiment, the polarizing plate may include a polarizing film, and a laminate of the retardation film of the present invention and a positive C plate formed on the lower surface of the polarizing film. The retardation film and the positive C plate may be sequentially formed from the polarizing film, or the positive C plate and the retardation film may be sequentially formed from the polarizing film. Through this, it is possible to increase the antireflection effect for external light. A polarizing plate may be laminated on the panel for a light emitting display device by further forming an adhesive film on the lower surface of the laminate.

The positive C plate may have a thickness direction retardation Rth of -40 nm to -80 nm at a wavelength of 550 nm. In the above range, it is possible to obtain an antireflection effect for external light together with the retardation film.

Hereinafter, the display device of the present invention will be described.

The display device of the present invention may include at least one of the retardation film of the present invention and the polarizing plate of the present invention. In an embodiment, the display device may include a liquid crystal display device, a light emitting device display device, and preferably a light emitting device display device. The light-emitting device display device includes an organic or organic-inorganic light-emitting device, for example, a light emitting material such as a light emitting diode (LED), an organic light emitting diode (OLED), a quantum dot light emitting diode (QLED), or a phosphor. It may mean a light emitting device.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are provided to help the understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Example One

In a state in which 9,9-bis[4-(2,3-epoxypropoxy)phenyl]fluorene and bisphenol A (compound of Formula 5-2) were dissolved at 100° C., 9,9- out of 100 mol% of the total number of moles Bis[4-(2,3-epoxypropoxy)phenyl]fluorene:bisphenol A was mixed in a molar ratio of 60:40, followed by solution polymerization. The obtained mixture was degassed at 180° C. and dried at 100° C. for 12 hours to prepare a phenoxy resin formed by reaction of 9,9-bis[4-(2,3-epoxypropoxy)phenyl]fluorene and bisphenol A. . The glass transition temperature of the phenoxy resin is 130°C.

The phenoxy resin prepared above was supplied to a 30 phi extruder in which nitrogen was substituted from the raw material hopper to the extruder. The mixture was melted at 250° C. to prepare raw pellets. The prepared raw material pellets were passed through a coat hanger type T die, and an unstretched film having a thickness of 100 μm was prepared through a chrome plating casting roll and a drying roll. The prepared unstretched film was uniaxially stretched twice and uniaxially in MD at a stretching temperature of 140° C. to prepare a uniaxially-stretched 50 μm-thick retardation film (glass transition temperature: 130° C.).

An 80 μm thick polyvinyl alcohol film (saponification degree: 99.5, degree of polymerization: 2000) was immersed in 0.3% iodine aqueous solution and dyed, followed by MD stretching so as to obtain a draw ratio of 5.0. Then, the stretched polyvinyl alcohol film was immersed in a 3% concentration of boric acid solution and 2% aqueous potassium iodide solution, respectively, for color correction in a complementary color process, and then dried at 50° C. for 4 minutes to prepare a polarizer (thickness 23 μm). A polarizing plate was prepared by laminating the retardation film and positive C layer (acrylic film: SDI) prepared above on the lower surface of the polarizer.

Example 2

A retardation film and a polarizing plate were prepared in the same manner as in Example 1, except that Example 1 was biaxially stretched by 2.5 times in MD and 1.1 times in TD.

Example 3

A retardation film and a polarizing plate were prepared in the same manner as in Example 1, except that Example 1 was biaxially stretched 1.1 times in MD and 2.6 times in TD.

Example 4

In Example 1, 9,9-bis[4-(2,3-epoxypropoxy)phenyl]fluorene:bisphenol A was mixed in a molar ratio of 90:10 and a phenoxy resin polymerized was used. A retardation film and a polarizing plate were prepared in the same manner as in 1 .

Example 5

Example 1 and Example 1 except that in Example 1, a phenoxy resin prepared by mixing bisphenol F (compound of Formula 5-1) in a molar ratio of 60:40 instead of bisphenol A (compound of Formula 5-2) was used A retardation film and a polarizing plate were prepared in the same manner.

Example 6

Example 1 and Example 1 except that in Example 1, a phenoxy resin prepared by mixing bisphenol Z (compound of Formula 5-3) in a molar ratio of 60:40 instead of bisphenol A (compound of Formula 5-2) was used A retardation film and a polarizing plate were prepared in the same manner.

comparative example One

A polycarbonate resin (T7430, Mitsubishi Corporation) was used at 240° C. using a T-die film making machine to prepare an unstretched film having a thickness of 100 μm. The prepared unstretched film was stretched 1.5 times in MD at 140° C. to prepare a retardation film and a polarizing plate having a thickness of 50 μm.

comparative example 2

Styrene-methacryl-maleic anhydride resin (R310, DENKA Corporation) was used at 260° C. using a T-die film making machine to prepare an unstretched film having a thickness of 100 μm. The prepared unstretched film was stretched 1.5 times in MD at 155° C. to prepare a retardation film and a polarizing plate having a thickness of 50 μm.

The following physical properties were evaluated for the retardation films prepared in Examples and Comparative Examples, and the results are shown in Tables 1 and 2 below.

(1) In-plane retardation (unit: nm), thickness-direction retardation (unit: nm) and degree of biaxiality: In-plane retardation (@wavelength 550nm, 450nm, 650nm) for the retardation films prepared in Examples and Comparative Examples using Axoscan was used to measure. In the same manner, the thickness direction retardation (@wavelength 550 nm) was measured using Axoscan.

(2) Haze (unit: %): The haze was measured for the retardation films prepared in Examples and Comparative Examples using a haze measuring device.

(3) Deviation of in-plane retardation (unit: nm): For the retardation films prepared in Examples and Comparative Examples, rectangular specimens of 3 cm in MD direction and 2 cm in TD direction were cut. Five points were marked at intervals of 0.3 cm in the MD direction on the obtained rectangular specimen, and the in-plane retardation at a wavelength of 550 nm was measured at the points. The difference between the maximum value and the minimum value among the measured in-plane phase differences was obtained, and the deviation of the in-plane phase difference was calculated according to Equation 1.

For the retardation films prepared in Examples and Comparative Examples, a rectangular specimen of 3 cm in the MD direction and 2 cm in the TD direction was cut. Five points were marked at intervals of 0.3 cm in the TD direction on the obtained rectangular specimen, and the in-plane retardation at a wavelength of 550 nm was measured at the points. The difference between the maximum value and the minimum value among the measured in-plane phase differences was obtained, and the deviation of the in-plane phase difference was calculated according to Equation 2.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Re(550) 145.63 142 143 135.23 143 138.6 Re(450) 126.59 117.86 120.12 113.12 119.15 120.9 Re(650) 152.69 151.94 151.58 143.54 152.39 144.9 Rth(550) 48 66 72 70 80 45 NZ 0.9714 0.966 0.9625 0.9645 0.9625 0.9745 Re(450)/Re(550) 0.87 0.83 0.84 0.84 0.83 0.87 Re(650)/Re(550) 1.05 1.07 1.06 1.06 1.07 1.05 haze 0.92 0.93 0.91 0.91 0.92 0.91 Deviation of Equation 1 3 3 3 3 3 2 Deviation of Equation 2 2 3 2 3 3 2

Comparative Example 1 Comparative Example 2 Re(550) 350 316 Re(450) 357 338.12 Re(650) 343 303.36 Rth(550) 190 -162 Re(450)/Re(550) 1.02 1.07 Re(650)/Re(550) 0.98 0.96 haze 0.9 0.92 Deviation of Equation 1 4 7 Deviation of Equation 2 3 6

As shown in Table 1, the retardation film of the present invention can minimize the deviation of the in-plane retardation in both MD and TD directions, has reverse wavelength dispersion, and can implement the in-plane retardation Re 100nm to 200nm at a wavelength of 550nm, and the haze is To provide a retardation film having low optical transparency and excellent optical transparency.

Simple modifications or changes of the present invention can be easily carried out by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (15)

A retardation film comprising a phenoxy resin having a repeating unit consisting of a unit of Chemical Formula 1 and a unit of Chemical Formula 2 as a base resin, wherein the retardation film has a deviation of the in-plane retardation of Equations 1 and 2, respectively, from 0 nm to 5 nm, the retardation film:
[Formula 1]

(In Formula 1, R ¹ , R ² are each independently an alkyl group having 1 to 5 carbon atoms, n and m are each independently an integer of 0 to 4, R ³ , R ⁴ are each independently 1 to 5 carbon atoms of an alkylene group).
[Formula 2]

(In Formula 2, A is -C(R ¹ R ² )-, R ¹ , R ² are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms, or R ¹ , R ² are connected to each other and have carbon atoms to form an alicyclic group having 5 to 7 carbon atoms).
[Equation 1]
Deviation of in-plane phase difference on the MD side = Re(max) - Re(min)
(In Equation 1, five points are marked at intervals of 0.3 cm in the MD direction for a rectangular specimen of 3 cm in the MD direction and 2 cm in the TD direction among the retardation films, and the in-plane retardation at a wavelength of 550 nm is measured and measured at the points. Among the in-plane phase differences, the maximum value is called Re(max) (unit: nm), and the minimum value is called Re(min) (unit: nm)).
[Equation 2]
Deviation of in-plane phase difference on the TD side = Re(max) - Re(min)
(In Equation 2, 5 points are marked at intervals of 0.3 cm in the TD direction for a rectangular specimen of 3 cm in the MD direction and 2 cm in the TD direction among the retardation films, and the in-plane retardation at a wavelength of 550 nm is measured and measured at the points. Among the in-plane phase differences, the maximum value is called Re(max) (unit: nm), and the minimum value is called Re(min) (unit: nm)).
According to claim 1, wherein the phenoxy resin is the number of moles of the unit of Formula 1: the unit of Formula 2 in a mole number of 50:50 to 90:10 among 100 mol% of the total number of moles of the unit of Formula 1 and the unit of Formula 2 What is included in the ratio, the retardation film.
The retardation film according to claim 2, wherein the mole ratio is 60:40 to 90:10.
The retardation film according to claim 1, wherein the phenoxy resin comprises a repeating unit of Formula 3 below as the repeating unit:
<Formula 3>

(In Formula 3, R ¹ , R ² , R ³ , R ⁴ , n, and m are as defined in Formula 1, and A is as defined in Formula 2).
According to claim 1, wherein in Formula 2, A is *-CH ₂ -*, *-C(CH ₃ ) ₂ -* or *-C(C ₅ H ₁₀ )-(* is a linkage site to the carbon of the phenyl group ), the retardation film.
The retardation film of claim 1, wherein the unit of Formula 1 does not have a polycyclic aromatic group.
The retardation film of claim 1, wherein the retardation film has a glass transition temperature of 115°C to 150°C.
The retardation film according to claim 1, wherein the retardation film satisfies the following formulas 3 and 4:
[Equation 3]
0.6 ≤ Re(450)/Re(550) ≤ 0.9
[Equation 4]
1.0 < Re(650)/Re(550) ≤ 1.3
(In Equation 3 and Equation 4, Re (450) is the in-plane retardation at a wavelength of 450 nm of the retardation film (unit: nm), Re (550) is the in-plane retardation at a wavelength of 550 nm of the retardation film (unit: nm), Re ( 650) is the in-plane retardation (unit: nm) at a wavelength of 650 nm of the retardation film.
The retardation film of claim 1, wherein the retardation film has an in-plane retardation Re of 100 nm to 200 nm at a wavelength of 550 nm.
The retardation film according to claim 1, wherein nx is 1.51 to 1.52, ny is 1.50 to 1.51, and nz is 1.505 to 1.515 at a wavelength of 550 nm in the retardation film.
The retardation film of claim 1, wherein the retardation film is a uniaxially oriented or biaxially oriented film.
The retardation film of claim 1, wherein the retardation film further contains rod-shaped nanoparticles.
polarizing film; and the retardation film of any one of claims 1 to 12 formed on one surface of the polarizing film.
The polarizing plate according to claim 13, wherein a positive C plate is further laminated on one surface of the retardation film.
A display device comprising the polarizing plate of claim 13 .