KR102567053B1 - Achromatic circular polarizer film and antireflection film for display containing with the same - Google Patents

Abstract

The present invention relates to an achromatic circular polarizing film, and more specifically, a retardation film in which the thickness of the retardation film in the circular polarizing film is made thinner than before while preventing or minimizing disclination due to lack of orientation. It relates to an achromatic circular polarizing film provided and a display using the same as an antireflection film for external light.

Description

Achromatic circular polarizing film and antireflection film for display including the same {ACHROMATIC CIRCULAR POLARIZER FILM AND ANTIREFLECTION FILM FOR DISPLAY CONTAINING WITH THE SAME}

The present invention relates to an achromatic circular polarizing film that can be applied as an external light antireflection film, a retardation film applied thereto, and a display, optical element, etc. to which the achromatic circular polarizing film is applied as an antireflection film.

In a display where light is emitted from a highly reflective surface such as OLED (Organic Light Emitting Diodes) or Micro LED (Micro Light Emitting Diodes, or mini LED), when external light is incident on the display panel, the light incident from the outside is reflected inside the display. There is a problem in that an optical signal emitted from the display is weakened due to reflection, resulting in performance degradation.

In order to solve this problem, a high-end display uses a circular polarizing plate having the same function as that shown in FIG. 1 . According to the structure shown in FIG. 1, light incident from the outside is changed into left circularly polarized light by the circular polarizing plate and is incident, and the polarization direction is changed into right circularly polarized light after being reflected by the reflector. The right-circularly polarized light is again extinguished by the left-circularly polarized plate. At this time, the observer observes only the optical signal emitted from the display or optical element as the external light is extinguished. That is, optical signal interference caused by external light is removed to improve the performance of the display or optical element.

In general, the circular polarization film applied as an antireflection film consists of a linear polarizer and a retardation film. If the retardation film used at this time is formed as a regular dispersion film, color characteristics deteriorate due to retardation deviation at long and short wavelengths than ideal QWP. In addition, there is a problem in that light leakage and color characteristic deterioration due to phase difference deviation in the viewing angle appear.

In order to solve these problems of the existing circular polarization film, a reverse dispersion film was applied as a retardation film, but the reverse dispersion film had a small refractive index anisotropy (Dn) and had to be formed very thickly, with a thickness of 3 μm or more. . In addition, a relatively large thickness reverse dispersion film requires a large orientation force during rubbing orientation or optical orientation, and when the orientation force is low, disclination, a kind of defect, occurs and reflects external light on the display. There is a problem that reduces performance.

Korean Patent Publication No. 10-2014-0077580 (published on 2014.06.24.)

The present invention has optimal optical properties for preventing or minimizing disclination due to lack of orientation while lowering the thickness of a reverse wavelength dispersion quarter-wavelength film among circular polarization films applied as an external light antireflection film. It is intended to provide a circular polarizing film to which a retardation film is applied and an antireflection film for a display having the same.

The achromatic circular polarizing film of the present invention for solving the above problems includes a retardation film and a polarizer on top of the retardation film, and the retardation film includes a quarter-wavelength film (hereinafter referred to as "QWP film").

As a preferred embodiment of the present invention, the quarter-wavelength film may include a reverse wavelength dispersion quarter-wavelength film (hereinafter referred to as "r-AQWP") or a flat wavelength dispersion quarter-wavelength film.

As a preferred embodiment of the present invention, in the achromatic circular polarizing film of the present invention, an optical axis angle between the polarizer and the retardation film may be 20° to 40°.

As a preferred embodiment of the present invention, the achromatic circular polarizing film of the present invention may further include a C plate layer on the other side of the retardation film on which the polarizer is stacked, or a C plate layer between the polarizer and the retardation film. .

As a preferred embodiment of the present invention, in the achromatic circular polarizing film of the present invention, the retardation film may further include a half-wavelength film (hereinafter referred to as "HWP") below or above the QWP film.

As a preferred embodiment of the present invention, the QWP film may include a quarter-wavelength film including a liquid crystal having a twist angle of 40° to 70°.

As a preferred embodiment of the present invention, the QWP film may satisfy the retardation on the optical axis of Equations 1 and 2 below.

[Equation 1]

0.830 ≤ α ≤ 1.050

[Equation 2]

0.960≤β≤1.200

In Equations 1 and 2, α is R ₄₅₀ /R ₅₅₀ , β is R ₆₅₀ /R ₅₅₀ , R ₄₅₀ denotes an optical axial retardation at a light wavelength of 450 nm, R ₅₅₀ denotes an optical axial retardation at a light wavelength of 450 nm, and R ₆₅₀ denotes an optical axial retardation at a light wavelength of 650 nm.

As a preferred embodiment of the present invention, the QWP film may have an optical axis retardation (R ₅₅₀ ) of 120 to 150 nm at a wavelength of 450 nm.

As a preferred embodiment of the present invention, the QWP film may have a thickness of 2.5 to 3.8 μm.

As a preferred embodiment of the present invention, the QWP film includes a liquid crystal layer and an alignment layer, and the liquid crystal layer may be formed of a liquid crystal resin including a polymerizable liquid crystal compound and a chiral dopant.

As a preferred embodiment of the present invention, the polymerizable liquid crystal compound may include a reverse wavelength liquid crystal compound having a refractive index of Equation 3 below and a forward wavelength liquid crystal compound having a refractive index of Equation 4 below.

[Equation 3]

0.040 ≤ │Δn ₁ │≤ 0.065

[Equation 4]

0.100 ≤ │Δn ₂ │≤ 0.150

In Equations 3 and 4, Δn ₁ and Δn ₂ respectively mean the difference between the refractive index of extraordinary light (n _e ) and the refractive index of normal light (n _o ).

As a preferred embodiment of the present invention, the polymerizable liquid crystal compound may include the reverse wavelength liquid crystal compound and the forward wavelength liquid crystal compound in a weight ratio of 1:0.05 to 0.55.

As a preferred embodiment of the present invention, when a chiral dopant is not used in the liquid crystal layer of the QWP film, the QWP film may satisfy the refractive index of Equation 5 below.

[Equation 5]

0.045 ≤ │Δn│≤ 0.070

In Equation 5, Δn means the difference between the refractive index of extraordinary light (n _e ) and the refractive index of normal light (n _o ).

As a preferred embodiment of the present invention, the C plate layer may include a homeotropic alignment liquid crystal polymer film and satisfy the refractive index of Equation 6.

[Equation 6]

n _z > n _x ≒ n _y

In Equation 6, n _x is the refractive index in the direction in which the refractive index in the plane in the slow axis direction is the maximum, n _y is the refractive index in the direction orthogonal to the slow axis in the plane and in the plane, and n _z means the refractive index in the thickness direction .

As a preferred embodiment of the present invention, the thickness direction retardation (R _th ) of the C plate layer according to Equation 1 below may be -120 nm to -30 nm.

[Equation 1]

_Rth = {(n _x +n _y )/2 - n _z }×d

In Equation 1, n _x is the refractive index in the direction in which the refractive index in the plane in the slow axis direction is the maximum, n _y is the refractive index in the direction orthogonal to the slow axis in the plane and in the plane, n _z is the refractive index in the thickness direction, d is is the thickness of the film.

Another object of the present invention relates to a retardation film applied to the achromatic circular polarizing film, and to provide a retardation film including a quarter-wavelength film having a thickness of 2.5 to 3.8 μm and a liquid crystal twist angle of 40° to 70°. .

Another object of the present invention is an antireflection film for a display, including the above-described circularly polarizing film.

As a preferred embodiment of the present invention, the display may be an Organic Light Emitting Diodes (OLED) display or a Micro Light Emitting Diodes (LED) display.

The circularly polarizing film of the present invention can prevent or minimize light leakage on the front and side surfaces and improve the color balance, and the retardation with a relatively thin thickness compared to the conventional ones. A circularly polarizing film to which the film is applied may be provided. Such a circularly polarizing film of the present invention is suitable for application as an external light antireflection film for OLED displays and micro LED displays requiring flexibility and thinness.

1 is a conceptual diagram explaining the antireflection principle of a conventional circular polarizing film composed of a polarizer and a retardation film.
2A to 2G each show a schematic diagram of the structure of the circularly polarizing film of the present invention.
3 is a polarization microscope measurement photograph of the reverse wavelength dispersion film prepared in Comparative Example 1 (A) and Example 1 (B) performed in Experimental Example 1.
4 is a simulation measurement result for light leakage characteristics of Preparation Example 1 (B), Preparation Example 2 (C), and Comparative Preparation Example 1 (A) conducted in Experimental Example 2.

Terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features or It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

In addition, the expression "~ on or ~ on top" or "~ on the bottom" means directionality, not only when the upper and lower components are in direct contact or spaced apart, but also include another component in the middle Including the case where there is, it means directionality.

The structural description of the achromatic circular polarizing film of the present invention is as follows.

As schematically shown in FIG. 2A, the achromatic circular polarizing film 100 of the present invention is applied to the upper part of the display unit (reflection layer) 1.

The achromatic circular polarization film includes a retardation film 10 and a polarizer 20 on top of the retardation film.

The retardation film may be composed of a quarter-wavelength film (hereinafter referred to as "QWP film"), and the QWP film may be a reverse wavelength dispersion quarter-wavelength film (hereinafter referred to as "r-AQWP film") or a flat wavelength quarter-wavelength film. can

In the achromatic circular polarizing film of the present invention, an optical axis angle between the polarizer and the retardation film may be 20° to 40°, preferably 22° to 38°. At this time, if the optical axis angle between the polarizer and the retardation film is less than 20°, there may be a problem of blue shift in color coordinates, and if the optical axis angle between the polarizer and the retardation film exceeds 40°, there may be a red shift in color coordinates. Therefore, it is preferable to combine the optical properties of the polarizer and the retardation film to satisfy the optical axis angle within the above range.

As shown schematically in FIG. 2B, the retardation film of the achromatic circular polarizing film of the present invention may be composed of the QWP film 12 alone, and as shown schematically in FIG. It is referred to as "HWP film", and may be a retardation film in which 14) is laminated.

In addition, as shown in FIGS. 2D and 2F, the achromatic circular polarizing film of the present invention is a structure in which a C plate layer 30 is formed under a retardation film (QWP film alone, or QWP film and HWP film two-layer structure). 2e and 2g, it may be a structure in which the C plate layer 30 is formed between the polarizer and the retardation film (QWP film alone, or QWP film and HWP film two-layer structure).

It is possible to directly attach the polarizer, retardation film, QWP film, HWP film, and C plate layer constituting the achromatic circular polarizing film of the present invention described above without a separate adhesive layer (or adhesive layer) for combining (or integrating) each. And, although not shown in FIG. 2, if necessary, when bonding (or bonding) between at least one layer, a transparent adhesive layer (OCA, Optically Clear Adhesive) or a transparent adhesive layer may be interposed.

The transparent pressure-sensitive adhesive layer may use an acrylic pressure-sensitive adhesive, and the acrylic pressure-sensitive adhesive includes an acrylic polymer having an alkyl (meth)acrylate monomer unit as a main skeleton as a base polymer. The average number of carbon atoms of the alkyl group of the alkyl (meth) acrylate constituting the main skeleton of the acrylic polymer is about 1 to 12, preferably one having 1 to 9 carbon atoms can be used. As specific examples of the alkyl (meth) acrylate, Methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, la There are uryl (meth)acrylates and the like, and these may be used alone or in combination of two or more.

The acrylic polymer may use a polymer or copolymer obtained by polymerizing or copolymerizing monomers to improve adhesion and heat resistance. Preferred examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate hydroxyl group-containing monomers such as (4-hydroxymethylcyclohexyl)-methyl acrylate; carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; Contains sulfonic acid groups such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl(meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid monomer; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; maleimide, N-cyclohexylmaleimide, N-phenylmaleimide; N-acryloylmorpholine; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methyl(meth)acrylamide, N-butyl (N-substituted) amide monomers such as (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide; Aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, 3-(3-pyrinidyl)propyl (meth)acrylate (meth)acrylic acid alkylaminoalkyl type monomers such as the like; (meth)acrylic acid alkoxyalkyl-based monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; and N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, succinimide-based monomers such as N-acryloylmorpholine; A polymer or copolymer obtained by polymerizing or copolymerizing one or more monomers selected from the above may be used as the acrylic polymer.

In addition, the achromatic circularly polarizing film of the present invention may further include a protective film on the polarizer.

In addition, the circular polarizing film of the present invention composed of a polarizer and a retardation film may have a front reflectance of 0.002400 or less, preferably 0.001700 to 0.002350, more preferably 0.001700 to 0.002300. In addition, the side reflectivity (θ = 50, Φ = 45 deg) may be 0.012000 or less, preferably 0.004000 to 0.011500, more preferably 0.005000 to 0.011000.

In addition, the circular polarizing film of the present invention composed of a polarizer, a retardation film, and a C plate layer may have a front reflectance of 0.002300 or less, preferably 0.001500 to 0.002300. In addition, the side reflectivity (θ = 50, Φ = 45 deg) may be 0.010000 or less, preferably 0.003000 to 0.009500, more preferably 0.003500 to 0.008500.

Each layer (or film) constituting the achromatic circular polarizing film of the present invention will be described in detail as follows.

[Polarizer]

In the present invention, the polarizer may use a stretched film in which a dye having absorption anisotropy is adsorbed or a film in which a dye having absorption anisotropy is applied and aligned, and a polarizer commercially available in the art may be used.

[Phase difference film]

In the present invention, as a retardation film, a very thin QWP film having a thickness of 2.5 to 3.8 μm, preferably a thickness of 2.70 to 3.60 μm, and more preferably a thickness of 2.85 to 3.50 μm may be applied.

In order to apply such a thin QWP film as a retardation film, the QWP film must satisfy the following optical properties to manufacture a circular polarizing film as an antireflection film.

The QWP film used in the present invention satisfies the retardation on the optical axis of Equations 1 and 2 below.

[Equation 1]

0.830≤α≤1.050, preferably 0.900≤α≤0.995, more preferably 0.920≤α≤0.990

[Equation 2]

0.960≤β≤1.200, preferably 0.965≤β≤1.150, more preferably 0.970≤β≤1.050

In Equations 1 and 2, α is R ₄₅₀ /R ₅₅₀ , β is R ₆₅₀ /R ₅₅₀ , R ₄₅₀ denotes an optical axial retardation at a light wavelength of 450 nm, R ₅₅₀ denotes an optical axial retardation at a light wavelength of 450 nm, and R ₆₅₀ denotes an optical axial retardation at a light wavelength of 650 nm.

And, the QWP film may be a reverse wavelength dispersion quarter-wavelength film that satisfies α<β.

In addition, the QWP film may be a flat wavelength dispersion quarter-wavelength film that satisfies α≒β.

In addition, the QWP film may have an optical axis retardation (R ₅₅₀ ) of 120 to 150 nm, preferably 125 to 145 nm, and more preferably 130 nm to 143 nm at a wavelength of 550 nm.

In addition, the QWP film includes a liquid crystal having a twist angle of 40° to 70°, preferably a twist angle of 50° to 70°, and more preferably a twist angle of 56° to 68°. Here, the twist angle means the twist angle of the liquid crystal from the bottom of the QWP film to the top when the direction close to the polarizer film is the top of the QWP film and the direction far from the polarizer film is the bottom of the QWP film, based on the polarizer film. . That is, it means the twisted angle of the upper liquid crystal based on the angle O° of the lower liquid crystal of the QWP film.

In addition, when a chiral dopant is not used in the liquid crystal layer of the QWP film, the QWP film may satisfy the refractive index of Equation 5 below.

[Equation 5]

0.045 ≤│Δn│≤ 0.070, preferably 0.048 ≤│Δn│≤ 0.065, more preferably 0.050 ≤│Δn│≤ 0.065

In Equation 5, Δn means the difference between the refractive index of extraordinary light (n _e ) and the refractive index of normal light (n _o ).

The QWP film for satisfying the above-described thickness and optical properties includes a liquid crystal layer formed of a liquid crystal resin containing a polymerizable liquid crystal compound and a chiral dopant, and an alignment layer for liquid crystal alignment. In addition, the alignment may be performed through rubbing alignment or optical alignment.

The polymerizable liquid crystal compound in the liquid crystal resin includes a reverse wavelength liquid crystal compound having a refractive index of Equation 3 below and a forward wavelength liquid crystal compound having a refractive index of Equation 4 below.

[Equation 3]

0.040 ≤│Δn ₁ │≤ 0.065, preferably 0.040 ≤│Δn ₁ │≤ 0.060, more preferably 0.040 ≤│Δn ₁ │≤ 0.048

[Equation 4]

0.100 ≤│Δn ₂ │≤ 0.150, preferably 0.110 ≤│Δn ₂ │≤ 0.150, more preferably 0.120 ≤│Δn ₂ │≤ 0.140

In Equations 3 and 4, Δn ₁ and Δn ₂ respectively mean the difference between the refractive index of extraordinary light (n _e ) and the refractive index of normal light (n _o ).

In addition, the polymerizable liquid crystal compound may include the reverse wavelength liquid crystal and the forward wavelength liquid crystal in a weight ratio of 1:0.05 to 0.55, preferably 1:0.10 to 0.45 weight ratio, more preferably 1:0.15 to 0.35 weight ratio. It can be included in weight ratio. At this time, if the weight ratio of the regular wavelength liquid crystal is less than 0.05, the alignment of the liquid crystal in the QWP film is insufficient and the optical properties cannot be matched with the polarizer, which may cause a linear lattice defect (disclination). Since the value of the retardation on the optical axis (α, β) of the film may not satisfy Equation 1 and/or Equation 2 above, it is recommended to use it within the above range.

Among the polymerizable liquid crystal compounds, one or a mixture of two or more reverse wavelength liquid crystal compounds satisfying the refractive index of Equation 3 may be used as the reverse wavelength liquid crystal.

As the reverse wavelength liquid crystal compound, at least one selected from commercially available nematic liquid crystal compounds and discotic liquid crystal compounds may be used.

As a reverse wavelength liquid crystal compound, the nematic liquid crystal compound is 2-(C ₁ ~C ₅ alkyl)-1,4-phenylenebis(4-(((4-(acryloyloxy)(C ₁ ~C ₅ alkoxy)carbonyl)oxy)benzoate ((2-(C ₁ ~C ₅ alkyl)-1,4-phenylene bis(4-(((4-(acryloyl oxy)(C ₁ ~C ₅ alkoxy) carbonyl)oxy)benzoate); a copolymer in which two or more polymers having one or more functional groups are copolymerized; and/or a disulfonic acid-based compound having a polycyclic structure.

Polymers having at least one functional group are poly(2,2'-disulfo-4,4'-benzidine terephthalamide, poly(2,2'-disulfo-4,4'-benzidine sulfoterephthalamide, poly( para-phenylene sulfoterephthalamide), poly(2-sulfo-1,4-phenylene sulfoterephthalamide), poly(2,2'-disulfo-4,4'-benzidine naphthalene-2,6-dicar Boxamide, poly(disulfobiphenylene-1,2-ethylene-2,2'-disulfobiphenylene), poly(2,2'-disulfobiphenylene-dioxyterephthaloyl), poly((2 ,2'-disulfobiphenyl-2-sulfodioxyterephthaloyl), poly(sulfophenylene-1,2-ethylene-2,2'-disulfobiphenylene), poly(2-sulfophenylene,1 ,2-ethylene-2'-sulfophenylene), poly(2,2'-disulfobiphenyl-2-sulfo-1,4-dioxymethylphenylene), poly(disulfo-quarterphenylethylene), poly( disulfo-terphenylethylene), poly(sulfo-biphenylethylene), poly(disulfo-biphenylethylene), poly(4,9-disulfobenzo[1,2-d;5,4-d'] Bisoxazole-1,7-ethylene), poly(benzo[1,2-d;5,4-d']bisoxazole-1,7-[1,1'-ethane-1,2-diyl- 2,2'-disulfodibenzene]), poly(4,9-disulfobenzo[1,2-d;5,4-d']bisoxazole-1,7-[1,1'-ethane -1,2-diyl-2,2'-disulfodibenzene]), poly(benzo[1,2-d;4,5-d']bisthiazole-1,7-[1,1'-ethane- 1,2-diyl-2,2'-disulfodibenzene]), poly(4,9-disulfobenzo[1,2-d;4,5-d']bisthiazole-1,7--[1 ,1'-ethane-1,2-diyl-2,2'-disulfodibenzene]), poly(4,4'-dimethylene-1-sulfobiphenyl)-(4,4'-deoxy-1 ,1'-disulfobiphenyl)ether) and poly(4,4'-dimethylene-1,1'-sulfobiphenyl)-(4,4'-dioxy-1,1'-disulfobiphenyl)ether ) may include one or more selected from among.

And, the functional group is -N=N-, , , , , or And, R, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ are independently a hydrogen atom, a C ₁ ~ C ₅ alkyl group, -SO ₃ H, -PO ₃ H ₂ , -(CH ₂ ) _m OH (where m is 1 to 5), -NH ₂ .

The polycyclic disulfonic acid-based compound is 4,4'-(5,5-dioxydibenzo[b,d]thien-3,7-diyl)dibenzenesulfonic acid, dinaphtho[2,3-b: 2',3'-d]furan disulfonic acid, 12H-benzene[b]phenoxazine disulfonic acid, dibenzo[b,i]oxantrene disulfonic acid, benzo[b]naphtho[2',3':5, 6]dioxino[2,3-i]oxantrene disulfonic acid, dibenzo[b,d]chrysene-7,14-dione disulfonic acid and/or 7-(4-sulfophenyl)dibenzo[b, d]thiophene-3-sulfonic acid-5,5-dioxide, wherein the disulfonic acid compound is -Cl, -Br, -NO ₂ , -F, -CF ₃ , -CN, -OH, -OCH ₃ , -OC ₂ H ₅ , -OCOCH ₃ , -OCN, -SCN, and -NHCOCH ₃ may include one or more substituents selected from one or more.

As a reverse wavelength liquid crystal compound, the discotic liquid crystal compound has negative refractive index anisotropy (uniaxial), for example, a benzene derivative, a cyclohexane derivative, an azacrown-based macrocycle or a phenylacetylene-based macrocycle at the molecular center. It can include a liquid crystal compound having a structure in which a linear alkyl group, an alkoxy group, a substituted benzoyloxy group, or the like is radially substituted as the mother nucleus. In addition, the discotic liquid crystal compound may be one having a polymerizable unsaturated group (eg, an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, etc.) that is cured by heat or light. there is.

Among the polymerizable liquid crystal compounds, the short-wavelength liquid crystal compound may be used by mixing one type or two or more types of short-wavelength liquid crystals that satisfy the refractive index of Equation 4 above.

At least one selected from commercially available nematic liquid crystal compounds and discotic liquid crystal compounds may be used as the long-wavelength liquid crystal compound.

Examples of the short-wavelength liquid crystal include, for example, a short-wavelength liquid crystal compound represented by Formula 1 and/or Formula 2 below, but is not limited thereto.

[Formula 1]

In Formula 1, R ¹ is -CH ₂ CH ₂ O(C=O)CHCH ₂ , -CH ₂ CH ₂ CH ₂ O(C=O)CHCH ₂ , -CH ₂ CH ₂ CH ₂ CH ₂ O(C =O)CHCH ₂ , is -CH ₂ CH ₂ CH ₂ O(C=O)CHCH ₂ CH ₃ , -CH ₂ CH ₂ CH ₂ CH ₂ O(C=O)CHCH ₂ CH ₃ and X is a halogen element , and n is 0 to 2.

[Formula 2]

X in Formula 2 is -C(=O)O- or -OC(=O)-, and each of R ¹ to R ⁶ may independently be a hydrogen atom, a halogen atom, an alkoxycarbonyl group, a cyano group, or a nitro group.

The liquid crystal resin used to form the QWP film and the liquid crystal layer is a polymerizable monomer, a polymerization initiator, a tilt control agent, a leveling agent, and a liquid crystal alignment in addition to the polymerizable liquid crystal compound within a range that does not significantly affect the optical properties of the QWP. An agent, an infrared absorbing dye, and/or a solvent may be further included. In addition to this, the liquid crystal resin may further include other additives such as a thixolytic agent, a gelling agent, an antioxidant, and an ultraviolet absorber.

<Chiral dopant>

The chiral dopant serves to induce spiral twist or enhance spiral twist when the liquid crystal compound in the liquid crystal layer is in a liquid crystal state, and a known chiral dopant used in the art may be used, preferably. may use a chiral compound polymerizable with the liquid crystal compound, a photosensitive chiral compound, or the like.

As an example of the polymerizable chiral compound, chiral compounds known in US Patent Publication No. US2003-0026922 and US Patent Registration No. US6217792 may be used. Preferably, a compound represented by Formula 3 below may be used. there is.

[Formula 3]

A in Formula 3 is -OC(=O)-, -C(=S)-O-, or is, preferably or am. In Formula 3, n is 1 to 4, preferably n is 2 to 3. Also, B in Formula 3 is a C ₂ -C ₈ straight-chain alkylene group, preferably a C ₃ -C ₅ straight-chain alkylene group.

A specific example of the polymerizable chiral compound is paliocolor LC 759 from BASF, which is commercially available.

In addition, the photosensitive chiral compound has a property of changing its helical twisting power depending on the wavelength and intensity of light it absorbs, and has a molecular structure with one or more chiral centers. , those having the property of forming photoisomers through a photoisomerization reaction by irradiation with light can be used. For a preferred example, a 2-benzylidene-p-menthanone-based compound may be used, and preferably a compound represented by Formula 4 below may be used.

[Formula 4]

In Formula 4, R ¹ is a C ₁ to C ₅ straight-chain alkyl group, C ₃ to C ₅ branched alkyl group, -COOH, -NH ₂ or C ₁ to C ₅ alkoxy group, and R ² is -CN, - NO ₂ , a phenyl group or an alkoxyphenyl group.

As a liquid crystal resin composition, when using a chiral compound, its amount is 0.20 to 1.60 parts by weight, preferably 0.30 to 1.35 parts by weight, preferably 0.50 to 1.32 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound of the liquid crystal resin. It is good. At this time, if the chiral compound is used in an amount of less than 0.20 parts by weight or more than 1.60 parts by weight, distortion of the liquid crystal in the liquid crystal layer may be insufficient or excessive, so that a desired twist angle may not be formed, so it is preferable to use it within the above range.

<Polymeric monomer>

The polymerizable monomer is an optional monomer capable of copolymerizing with a polymerizable liquid crystal compound as an additive component for adjusting the wavelength dispersion characteristics of the retardation film and increasing the high-temperature and moist heat durability through improved dispersibility, and 4-(2-methacryloyl oxyethyloxy)benzoic acid-4'-methoxyphenyl, 4-(6-methacryloyloxyhexyloxy)benzoic acid biphenyl, 4-(2-acryloyloxyethyloxy)benzoic acid-4'-cyano Biphenyl, 4-(2-methacryloyloxyethyloxy)benzoic acid-4'-cyanobiphenyl, 4-(2-methacryloyloxyethyloxy)benzoic acid-3',4'-difluoro Phenyl, 4-(2-methacryloyloxyethyloxy)benzoate naphthyl, 4-acryloyloxy-4'-decylbiphenyl, 4-acryloyloxy-4'-cyanobiphenyl, 4- (2-acryloyloxyethyloxy)-4'-cyanobiphenyl, 4-(2-methacryloyloxyethyloxy)-4'-methoxybiphenyl, 4-(2-methacryloyl Oxyethyloxy)-4'-(4"-fluorobenzyloxy)-biphenyl, 4-acryloyloxy-4'-propylcyclohexylphenyl, 4-methacryloyl-4'-butylbicyclohexyl , 4-acryloyl-4'-amyltolan, 4-acryloyl-4'-(3,4-difluorophenyl)bicyclohexyl, 4-(2-acryloyloxyethyl)benzoic acid (4 -amylphenyl) and 4-(2-acryloyloxyethyl)benzoic acid (4-(4'-propylcyclohexyl)phenyl).

As the composition of the liquid crystal resin, the amount of the polymerizable monomer used is 0.50 to 10.00 parts by weight, preferably 1.00 to 8.00 parts by weight, preferably 3.0 to 7.0 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound of the liquid crystal resin. It is good.

<Polymerization Initiator>

The polymerization initiator is a radical polymerization initiator, and a thermal radical initiator and/or an optical radical initiator may be used, preferably an optical radical initiator. Photo-radical initiators include acetophenone-based compounds, biimidazole-based compounds, triazine-based compounds, O-acyloxime-based compounds, onium salt-based compounds, benzoin-based compounds, benzophenone-based compounds, α-diketone-based compounds, and polynuclear quinones. At least one selected from paddy-based compounds, diazo-based compounds, and imidosulfonate-based compounds may be used.

The acetophenone-based compound is 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1- one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2- It may include at least one selected from diphenylethane-1-one, 1,2-octanedione, and 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone.

The biimidazole-based compound is 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetrakis(4-ethoxycarbonylphenyl)-1,2'- Biimidazole, 2,2'-bis(2-bromophenyl)-4,4',5,5'-tetrakis(4-ethoxycarbonylphenyl)-1,2'-biimidazole, 2 ,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)- 4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'- Tetraphenyl-1,2'-biimidazole, 2,2'-bis(2-bromophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2, 2'-bis(2,4-dibromophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole and 2,2'-bis(2,4,6-tribe lomophenyl) -4,4', 5,5'-tetraphenyl-1,2'-biimidazole.

As an optical radical initiator, commercially available BASF's Irgacure907, Irgacure 184, Irgacure 369, Irgacure 651, Irgacure 819, Irgacure907, Irgacure OXE02, etc. may be used, or Adekaoptomer N1919 from ADEKA may be used.

As the composition of the liquid crystal resin, the amount of the polymerization initiator is 0.05 to 4.00 parts by weight, preferably 0.1 to 2.0 parts by weight, preferably 0.2 to 1.0 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound of the liquid crystal resin. good night.

<Leveling agent>

The leveling agent serves to improve the leveling property of the surface of the retardation film while improving the dispersibility of the liquid crystal compound in the liquid crystal layer, and a fluorine-based surfactant and/or a silicone-based surfactant may be used. In addition, as the fluorine-based surfactant, a pentaerythritol-based surfactant or a dipentaerythritol-based surfactant may be used. As an example of the pentaerythritol-based surfactant, there is a compound represented by Formula 5 below, but the present invention is not limited thereto.

[Formula 5]

In Formula 5, R ¹ is a methylene group, an ethylene group, or a propylene group, and each of R ² to R ⁴ is independently -C _n F _2n+1 , -C _n F _2n H, -CF ₂ O(C ₂ F ₄ )OCF ₃ , or am.

As a liquid crystal resin composition, when using a leveling agent, its amount is 0.5 to 10.00 parts by weight, preferably 0.8 to 7.5 parts by weight, preferably 1.0 to 5.0 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound of the liquid crystal resin. good night.

<liquid crystal aligning agent>

The liquid crystal alignment agent is a polymer having an optical alignment group, and the optical alignment group may include an azobenzene-containing group, a cinnamic acid structure-containing group, a chalcone-containing group, a benzophenone-containing group, and/or a coumarin-containing group. In addition, the polymer may include at least one polymer selected from polyorganosiloxane, styrene-maleimide-based copolymer, acrylic polymer, polyamic acid, polyimide, and polyamic acid ester.

As the composition of the liquid crystal resin, when using the liquid crystal aligning agent, its amount is 2.00 to 10.00 parts by weight, preferably 2.00 to 7.00 parts by weight, preferably 2.0 to 5.0 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound of the liquid crystal resin. It is good.

<Infrared ray absorbing dye>

As the infrared absorbing dye, any dye absorbing light with a wavelength of 680 to 900 m may be used without particular limitation. Preferably, the infrared absorbing dye is a dichroic dye having different absorbances in the direction of the major axis of the molecule and the absorbance in the direction of the minor axis of the molecule. Examples of such infrared absorbing pigments include diketopyrrolopyrrole pigments, diimmonium pigments, phthalocyanine pigments, naphthalocyanine pigments, azo pigments, polymethane pigments, anthraquinone pigments, There are pyrylium-based pigments, squarylium-based pigments, triphenylmethane-based pigments, cyanine-based pigments, and aminium-based pigments.

As the composition of the liquid crystal resin, when using the infrared absorbing dye, its amount is 1.00 to 15.00 parts by weight, preferably 1.50 to 10.00 parts by weight, preferably 2.0 to 5.0 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound of the liquid crystal resin. It is good.

<Tilt control agent>

The tilt control agent serves to control the tilt angle by reducing or increasing the tilt angle of the liquid crystalline compound, and may include at least one selected from a compound represented by Formula 6 and a polymer represented by Formula 7 there is.

[Formula 6]

R ¹ and R ² in Formula 6 are independently a hydrogen atom, -(OCH ₂ ) _n C ₆ F ₁₃ , -(OCH ₂ CH ₂ ) _n C ₆ F ₁₃ , -(OCH ₂ CH ₂ CH ₂ ) _n C ₆ F ₁₃ or -(OCH ₂ CH ₂ CH ₂ CH ₂ ) _n C ₆ F ₁₃ , where n is an integer from 1 to 3.

[Formula 7]

R ¹ and R ⁸ in Formula 7 are independently a hydrogen atom, -OH, -COOH or -SO ₃ H, and R ² , R ⁴ and R ⁶ are independently a hydrogen atom, a C ₁ ~ C ₃ alkyl group or -COOH And, R ³ , R ⁵ and R ⁷ are independently -COOH, -COOCH ₂ (CF ₂ ) _n H, -COOCH ₂ CH ₂ (CF ₂ ) _n H or -COOCH ₂ CH ₂ OH, and n is 3 to is an integer of 10, x is an integer of 40 to 100, y is an integer of 10 to 30, and z is an integer of 2 to 10.

As a composition of the liquid crystal resin, when using the tilt control agent, its amount is 0.001 to 2.00 parts by weight, preferably 0.01 to 1.80 parts by weight, preferably 0.1 to 1.5 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound of the liquid crystal resin. It is good.

<Solvent>

The solvent is propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol ethyl methyl ether, tetrahydrofuran, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl acetate, acetate n -Butyl, isobutyl acetate, t-butyl acetate, ethyl acetoacetate, propylene glycol monomethyl ether acetate, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, 1 , 2-dimethyl-2-imidazolidinone and N,N-dimethylformamide may contain one or two or more selected from among. In addition, the amount of solvent used is 50 to 150 parts by weight, preferably 50 to 120 parts by weight, more preferably 80 to 120 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound. At this time, if the solvent amount is less than 50 parts by weight, the viscosity of the liquid crystal resin is too high and the coating workability is too poor, and using 150 parts by weight of the liquid crystal resin is too low to adversely affect the liquid crystal orientation. It is good.

<Alignment layer>

The alignment layer may be prepared by coating, drying, and rubbing a resin for an alignment layer on a support.

The application is a coating commonly known in the art such as curtain coating, extrusion coating, roll coating, spin coating, dip coating, bar coating, spray coating, slide coating, print coating, gravure coating, die coating, cap coating or dip coating. Dispensing can be done by law.

In addition, the resin for the alignment layer may include a polymer including at least one selected from polyimide, polyvinyl alcohol, polyester, polyallylate, polyamideimide, and polyetherimide.

And, the thickness of the alignment layer may be 0.001 ~ 2.00 ㎛, preferably 0.001 ~ 1.00 ㎛.

In addition, a known support may be used as the support, and preferably, a support made of a material capable of being separated from the alignment layer after formation of the alignment layer may be used. For example, the support may be a polyolefin resin such as polyethylene, polypropylene, norbornene-based polymer; Cyclic olefin resin; polyvinyl alcohol resin; polyethylene terephthalate resin; polymethacrylic acid ester resin; polyacrylic acid ester resin; cellulose ester resins such as triacetyl cellulose resin, diacetyl cellulose resin, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate resin; polysulfone resin; polyethersulfone resin; polyether ketone resin; polyphenylene sulfide resin; and polyphenylene oxide resin; One made of a resin containing at least one selected from among may be used.

In addition, the surface of the support may be subjected to release treatment such as silicon treatment.

[HWP film]

As described above, the retardation film of the present invention may further include an HWP film.

The HWP film may be introduced by forming it on top of the QWP film so as to exist between the polarizer and the QWP.

Further, the HWP film may use a stretched film or may use a liquid crystal polymer film including a liquid crystal layer formed of a liquid crystal resin containing a polymerizable liquid crystal compound and an alignment layer for liquid crystal alignment. In addition, the alignment may be performed through rubbing alignment or optical alignment.

[C plate layer]

The C plate layer used in the present invention is a liquid crystal polymer film, or may be formed by coating a retardation film or a polarizer with a liquid crystal polymer.

And, when the C plate layer is a liquid crystal polymer film, it may be a stretched film or a film in which a liquid crystal layer made of liquid crystal polymer and an alignment film layer for aligning liquid crystals are laminated. In addition, the alignment may be performed through rubbing alignment or optical alignment.

The liquid crystal polymer film constituting the C plate layer may be a vertically aligned liquid crystal polymer film that satisfies the refractive index of Equation 6.

[Equation 6]

n _z > n _x ≒ n _y

In Equation 6, n _x is the refractive index in the direction in which the refractive index in the plane in the slow axis direction is the maximum, n _y is the refractive index in the direction orthogonal to the slow axis in the plane and in the plane, and n _z means the refractive index in the thickness direction .

In addition, the C plate layer may have a thickness direction retardation (R _th ) of -120 nm to -30 nm, preferably -90 nm to -60 nm according to Equation 1 below, and a circular polarization film to which the C plate layer is applied It can be applied by adjusting it according to a large TV display, mobile display, rollable display, etc. to which the (anti-reflection film) is to be applied.

[Equation 1]

_Rth = {(n _x +n _y )/2 - n _z }×d

In Equation 1, n _x is the refractive index in the direction in which the refractive index in the plane in the slow axis direction is the maximum, n _y is the refractive index in the direction orthogonal to the slow axis in the plane and in the plane, n _z is the refractive index in the thickness direction, d is is the thickness of the film.

Hereinafter, the present invention will be described in more detail through examples, but the following examples are not intended to limit the scope of the present invention, which should be interpreted to aid understanding of the present invention.

[Example]

Example 1: Preparation of retardation film (r-AQWP film)

(1) Manufacture of liquid crystal resin

2-(C ₁ alkyl)-1,4-phenylenebis(4-(((4-(acryloyloxy)(C ₄ alkoxy)carbonyl)oxy)benzoate and benzo[b]naphtho A reverse wavelength liquid crystal compound containing [2',3':5,6]dioxino[2,3-i]oxantrene disulfonic acid in a weight ratio of 1:0.5 was prepared. It satisfies the refractive index (Δn ₁ ) of -1.

Then, a positive-wavelength liquid crystal compound represented by Chemical Formula 1-1 was prepared. The constant wavelength liquid crystal compound satisfies the refractive index (Δn ₂ ) of Equation 4-1 below.

[Formula 1-1]

In Formula 1-1, R ¹ is -CH ₂ CH ₂ CH ₂ CH ₂ O(C=O)CHCH ₂ , and n is 0.

[Equation 3-1]

0.042 ≤│Δn ₁ │≤ 0.048

[Equation 4-1]

0.125 ≤│Δn ₂ │≤ 0.135

In Equation 3-1 and Equation 4-1, Δn ₁ and Δn ₂ respectively mean the difference between the refractive index of extraordinary light (n _e ) and the refractive index of normal light (n _o ).

Next, a polymerizable liquid crystal compound was prepared so that the reverse wavelength liquid crystal compound and the forward wavelength liquid crystal compound were mixed in a weight ratio of 1:0.2.

Based on 100 parts by weight of the polymerizable liquid crystal compound, 1.1 parts by weight of a polymerizable chiral dopant (paliocolor LC 759 from BASF), a polymerizable monomer, 4-(2-methacryloyloxyethyloxy)-4'-( 3.8 parts by weight of 4″-fluorobenzyloxy)-biphenyl, 0.32 parts by weight of Irgacure 907 (BASF) as an optical radical initiator, 4.0 parts by weight as a leveling agent, 2.2 parts by weight of a polyamic acid ester polymer having a coumarin-containing group as a liquid crystal alignment agent A liquid crystal resin was prepared by mixing 0.64 parts by weight of a tilt control agent, a compound represented by Formula 6-1, and 87 parts by weight of a mixed solvent in which propylene glycol monomethyl ether and N-methyl-2-pyrrolidone were mixed as solvents.

[Formula 6-1]

R ¹ and R ² in Formula 6-1 are -(OCH ₂ CH ₂ CH ₂ ) _n C ₆ F ₁₃ , and n is 2.

[Formula 5-1]

In Formula 5-1, R ¹ is a methylene group, and each of R ² , R ³ , and R ⁴ is -CF ₂ O(C ₂ F ₄ )OCF ₃ .

(2) film formation

An alignment film in which an alignment film layer having a thickness of 0.3 µm was formed on an upper portion of a cellulose ester support (substrate) having a thickness of 60 µm was prepared.

After bar-coating and applying the previously prepared liquid crystal resin to the alignment layer, drying at about 120° C. for 60 seconds, UV irradiation (wavelength: 365 nm, light intensity: 500 mJ/cm ² ) with a high-pressure mercury lamp under a nitrogen atmosphere, and curing. By forming a liquid crystal layer, an r-AQWP film (retardation film) was prepared.

In the retardation film, the total thickness of the alignment layer and the liquid crystal layer excluding the support was 3.10 μm.

Examples 2 to 6

A liquid crystal resin and a retardation film were prepared in the same manner as in Example 1, but as shown in Table 1 below, the liquid crystal resin was prepared by varying the weight ratio of the reverse wavelength liquid crystal compound and the forward wavelength liquid crystal compound in the liquid crystal resin, and then the retardation film was used. was prepared, and Examples 2 to 6 were carried out, respectively.

Comparative Example 1

A liquid crystal resin and a retardation film were prepared in the same manner as in Example 1, but as a liquid crystal compound in the liquid crystal resin, only a reverse wavelength liquid crystal compound was used and the liquid crystal resin was prepared without using a chiral dopant, and then the liquid crystal resin A retardation film having a thickness of 3.44 μm was prepared by using.

Comparative Example 2

A liquid crystal resin and a retardation film were prepared in the same manner as in Example 1, but as shown in Table 1 below, the liquid crystal resin was prepared by varying the weight ratio of the reverse wavelength liquid crystal compound and the forward wavelength liquid crystal compound in the liquid crystal resin, and then using this to prepare a 2.12㎛ A thick retardation film was prepared.

Comparative Example 3

A liquid crystal resin and a retardation film were prepared in the same manner as in Example 1, except that 2 parts by weight of a chiral dopant was used, and the liquid crystal resin was prepared in the same manner and composition as in Example 1, and then the retardation was made using the liquid crystal resin. A film was made.

division in liquid crystal resin
Reverse wavelength liquid crystal and forward wavelength liquid crystal compound weight ratio Chiral dopant usage Example 1 1:0.25 1.1 parts by weight Example 2 1:0.11 1.1 parts by weight Example 3 1:0.18 1.1 parts by weight Example 4 1:0.43 1.1 parts by weight Example 5 1:0.53 1.1 parts by weight Example 6 1:0.25 1.3 parts by weight Comparative Example 1 1:0 0 Comparative Example 2 1:0.77 1.1 parts by weight Comparative Example 3 1:0.25 2.0 parts by weight

Experimental Example 1: Measurement of optical properties of retardation film

Optical axis retardation and refractive index (Δn = difference between extraordinary light refractive index (n _e ) and normal light refractive index (n _o )) of the retardation films prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 2 below. The thickness reduction rate in Table 2 below is calculated and shown based on the thickness of the retardation film of Comparative Example 1.

division optical on-axis phase difference index of refraction
(Δn) thickness reduction rate
(thickness) twist angle
α β Comparative Example 1 0.841 1.029 0.04 0% (3.44㎛) 10° or less Example 1 0.978 0.991 - 9.88% (3.10㎛) 58-62° Example 2 0.936 1.018 - 2.62% (3.35㎛) 60-64° Example 3 0.955 1.002 - 4.94% (3.27㎛) 59-63° Example 4 0.988 0.989 - 17.44% (2.84㎛) 56-60° Example 5 0.992 0.982 - 24.42% (2.60㎛) 55-59° Example 6 0.977 0.990 - 5.5% (3.25㎛) 66-67° Comparative Example 2 1.105 0.921 - 38.37% (2.12㎛) 54-58° Comparative Example 3 0.959 1.005 - 4.07% (3.30㎛) 110 to 114° α is R ₄₅₀ /R ₅₅₀ , β is R ₆₅₀ /R ₅₅₀ , R ₄₅₀ is the optical on-axis retardation at a light wavelength of 450 nm, R ₅₅₀ is the optical on-axis retardation at a light wavelength of 450 nm, and R ₆₅₀ is the optical on-axis retardation at a light wavelength of 650 nm.

Looking at the measurement results of optical properties in Table 2, it can be seen that the retardation films of Comparative Example 1 and Examples 1 to 4 exhibit reverse wavelength dispersion or flat dispersion characteristics. On the other hand, Example 5 had a constant wavelength dispersion characteristic range but showed almost flat dispersion characteristics, and Comparative Example 2 had a problem in that the film thickness was thin but had a positive wavelength dispersion characteristic.

In addition, in the case of Comparative Example 1, the reverse wavelength dispersion is high, but the polarization microscope image (200 times) of the film prepared in Example 1 and Comparative Example 1 in A (Example 1) and B (Comparative Example 1) of FIG. ), and looking at this, in the case of Comparative Example 1, it can be confirmed that disclination, which is an alignment defect, has occurred. In contrast, it was confirmed that the film of Example 1 did not have such defects.

In addition, in the case of Comparative Example 3 using an excessive amount of chiral dopant, there was a very high twist angle exceeding 70 °.

Production Example 1: Production of circular polarizing film

After applying a transparent adhesive film (OCA, Optically Clear Adhesive) and forming an adhesive layer on top of a 200 μm-thick stretched polarizer (manufacturer: LG Chem), the retardation film prepared in Example 1 was laminated on top of the adhesive layer and A circular polarizer was prepared by drying.

Preparation Example 2

In the circular polarizing film of Preparation Example 1, a 0.9 μm-thick C plate (manufacturer: Clap Co., Ltd.) was laminated under the retardation film to prepare a circular polarizer.

The C plate satisfies the refractive index of Equation 6 below, and has a thickness direction retardation (R _th ) of -80 to -83 nm.

[Equation 6]

n _z > n _x ≒ n _y

In Equation 6, n _x is the refractive index in the direction in which the refractive index in the plane in the slow axis direction is the maximum, n _y is the refractive index in the direction orthogonal to the slow axis in the plane and in the plane, and n _z means the refractive index in the thickness direction .

Comparative Preparation Example 1

After applying a transparent adhesive film (OCA, Optically Clear Adhesive) and forming an adhesive layer on top of a 200 μm-thick stretched polarizer (manufacturer: LG Chem), the retardation film prepared in Comparative Example 3 was laminated on top of the adhesive layer and A circular polarizer was prepared by drying.

Experimental Example 2: Measurement of optical properties of circularly polarizing film 2

Simulation measurements (color contour) were performed on the light leakage characteristics of the circular polarizing films of Preparation Examples 1 to 2 and Comparative Preparation Example 1, and the results were shown in A (Comparative Preparation Example 1), B (Production Example 1) and C in FIG. 4. (Production Example 2). In addition, simulator data and thickness direction retardation (R _th ) for front reflectivity and side reflectivity, which are simulation measurement data, are shown in Table 3 below.

In addition, the optical axis angles of the retardation film and the polarizer of Preparation Examples 1 to 7 and Comparative Preparation Example 1 were measured, and the results are shown in Table 3 below.

division phase difference
film circular polarization film
reflectivity phase difference film
polarizer
optical axis angle face side
(measurement standard:
θ=50, Φ=45 degrees) Preparation Example 1 Example 1 0.002220 0.010082 25° (±0.2°) Preparation Example 2 Example 1 0.000222 0.006016 - Preparation Example 3 Example 2 0.002003 0.007692 - Production Example 4 3 in implementation 0.002122 0.008764 - Preparation Example 5 Example 4 0.002317 0.011080 - Preparation Example 6 Example 5 0.002372 0.011542 - Preparation Example 7 Example 6 0.002284 0.009073 22° (±0.2°) Comparative Preparation Example 1 Comparative Example 3 0.002473 0.012091 45° (±0.2°)

Looking at the physical property measurement results in Table 3, it was confirmed that the circular polarizing films prepared in Preparation Examples 1 to 7 had very excellent antireflection with a frontal reflectance of 0.002400 or less and a side reflectance of 0.012000 or less. In addition, Preparation Example 2 in which the C plate was formed showed lower reflectivity measurement results on both the front and side surfaces than Preparation Example 1, and through this, it was confirmed that the antireflection effect was increased during the formation of the C plate. These optical characteristics could also be confirmed through B and C of FIG. 4 .

And, looking at Preparation Example 1 and Preparation Examples 2 to 6, as the amount of constant wavelength liquid crystal used in the retardation film increased, the side reflectance value increased, and the antireflection effect tended to decrease.

In addition, Comparative Preparation Example 1 prepared with a retardation film without using a chiral dopant showed a relatively poor antireflection effect, although the thickness of the retardation film itself was thin compared to Preparation Examples 1 and 2, and the optical axis Angle values tended to be high.

Although the preferred embodiments of the present invention have been described and illustrated using specific terms above, such terms are only used to clearly explain the present invention, and the embodiments and described terms of the present invention are the technical spirit and scope of the following claims. It is obvious that various changes and changes can be made without departing from the scope. Such modified embodiments should not be individually understood from the spirit and scope of the present invention, and should be said to fall within the scope of the claims of the present invention.

Reference Numerals 1: reflective layer (display unit) 10: retardation film
12: QWP film (r-AQWP film or flat dispersion film) 14: HWP film
20: polarizer 30: C plate layer
100: achromatic circular polarization film

Claims (13)

A circularly polarizing film with a frontal reflectance of 0.002400 or less and a side reflectivity (measured under θΦdeg conditions) of 0.012000 or less,
The circular polarization film includes a retardation film and a polarizer on top of the retardation film,
The retardation film includes a quarter-wavelength film containing liquid crystal having a twist angle of 50 ° to 70 °,
The quarter-wavelength film includes a reverse wavelength dispersion film or a flat wavelength dispersion film,
The quarter-wavelength film satisfies the retardation on the optical axis of Equations 1 and 2 below, and has a thickness of 2.5 to 3.8 μm,
The quarter wave film includes a liquid crystal layer and an alignment layer,
The liquid crystal layer is formed of a liquid crystal resin containing a polymerizable liquid crystal compound, a polymerizable monomer, a chiral dopant, a polymerization initiator, a leveling agent, a liquid crystal alignment agent, a tilt control agent, and a solvent,
The liquid crystal resin includes 0.20 to 1.60 parts by weight of the chiral dopant based on 100 parts by weight of the polymerizable liquid crystal compound,
The polymerizable liquid crystal compound includes a reverse wavelength liquid crystal compound having a refractive index of Equation 3 and a forward wavelength liquid crystal compound having a refractive index of Equation 4 below in a weight ratio of 1: 0.05 to 0.55,
The tilt control agent comprises at least one selected from a compound represented by Formula 6 and a polymer represented by Formula 7;
[Equation 1]
0.830 ≤ α ≤ 1.050
[Equation 2]
0.960≤β≤1.200
In equations 1 and 2, α is R₄₅₀/R₅₅₀, and β is R₆₅₀/R₅₅₀ego, R₄₅₀Optical on-axis retardation at a silver light wavelength of 450 nm, R₅₅₀Optical on-axis retardation at a silver light wavelength of 450 nm, R₆₅₀denotes the optical on-axis retardation at a light wavelength of 650 nm.
[Equation 3]
0.040 ≤ │Δ_One│≤ 0.065
[Equation 4]
0.100 ≤ │Δ₂│≤ 0.150
In equations 3 and 4, Δ_One and Δ₂ Each is an extraordinary light refractive index (n_e) and normal light refractive index (n_o) means the difference of
[Formula 6]

R in Formula 6^One and R²are independently a hydrogen atom, -(OCH₂)_nC₆F₁₃, -(OCH₂CH₂)_nC₆F₁₃, -(OCH₂CH₂CH₂)_nC₆F₁₃or -(OCH₂CH₂CH₂CH₂)_nC₆F₁₃, and n is an integer from 1 to 3.
[Formula 7]

R in Formula 7^One and R⁸is independently a hydrogen atom, -OH, -COOH or -SO₃H and R², R⁴ and R⁶is independently a hydrogen atom, C_One~C₃An alkyl group of or -COOH, R³, R⁵ and R⁷are independently -COOH, -COOCH₂(CF₂)_nH, -COOCH₂CH₂(CF₂)_nH or -COOCH₂CH₂OH, n is an integer from 3 to 10, x is an integer from 40 to 100, y is an integer from 10 to 30, and z is an integer from 2 to 10.
The achromatic circularly polarizing film according to claim 1, wherein R ₅₅₀ is 120 to 150 nm.
delete The achromatic circularly polarizing film according to claim 1, wherein an optical axis angle between the polarizer and the retardation film is 20° to 40°.
delete delete The achromatic circular polarizing film according to claim 1, further comprising a C plate layer on the other side of the retardation film on which the polarizer is stacked, or further comprising a C plate layer between the polarizer and the retardation film.
The achromatic circularly polarizing film according to claim 1, wherein the retardation film further comprises a half-wavelength film under or above the quarter-wavelength film.
8. The method of claim 7, wherein the C plate layer includes a homeotropic liquid crystal polymer film, and an achromatic circular polarization film, characterized in that it satisfies the refractive index of Equation 6;
[Equation 6]
n _z > n _x ≒ n _y
In Equation 6, n _x is the refractive index in the direction in which the refractive index in the plane in the slow axis direction is the maximum, n _y is the refractive index in the direction orthogonal to the slow axis in the plane and in the plane, and n _z means the refractive index in the thickness direction .
The achromatic circularly polarizing film according to claim 7 , wherein the C plate layer has a thickness direction retardation (R _th ) of -120 nm to -30 nm according to Equation 1 below;
[Equation 1]
_Rth = {(n _x +n _y )/2 - n _z }×d
In Equation 1, n _x is the refractive index in the direction in which the refractive index in the plane in the slow axis direction is the maximum, n _y is the refractive index in the direction orthogonal to the slow axis in the plane and in the plane, n _z is the refractive index in the thickness direction, d is is the thickness of the film.
delete An antireflection film for a display comprising the circular polarizing film of any one of claims 1, 2, 4, and 7 to 10.
The antireflection film for a display according to claim 12, wherein the display is an Organic Light Emitting Diodes (OLED) display or a Micro LED (Light Emitting Diodes) display.