KR102584388B1 - Retardation film, polarizing plate comprising same, liquid crystal display device comprising the same and manufacturing method of retardation film - Google Patents

Abstract

The present invention relates to a retardation film, a polarizing plate including the same, a liquid crystal display device including the same, and a method of manufacturing the retardation film.

Description

Retardation film, polarizer including the same, liquid crystal display device including the same, and method of manufacturing the retardation film

The present invention relates to a retardation film, a polarizing plate including the same, a liquid crystal display device including the same, and a method of manufacturing the retardation film.

Based on recent developments in optical technology, various devices such as plasma display panels (PDP), liquid crystal displays (LCD), and organic light emitting diodes (OLED) are being developed to replace conventional cathode ray tubes. Display devices using this method have been proposed and are commercially available. Recently, the characteristics required for these display devices are becoming more sophisticated, and accordingly, the characteristics required for peripheral components such as optical films applied to display devices are also becoming more sophisticated. In particular, as display devices have recently become thinner, lighter, and larger in screen area, wide viewing angles, high contrast, suppression of image color tone changes depending on viewing angle, and uniform screen display have become particularly important issues.

In general, a liquid crystal display device has a basic configuration in which polarizers are installed on both sides of a liquid crystal cell. The orientation of the liquid crystal cell changes depending on whether an electric field is applied to the driving circuit, and the specific transmittance emitted through the polarizer changes accordingly, thereby changing the light visualization is achieved. At this time, the light path and birefringence change depending on the incident angle of the incident light, because liquid crystal is an anisotropic material with two different refractive indices.

Due to these characteristics, the contrast ratio of liquid crystal displays, which is a measure of how clearly an image is visible, varies depending on the viewing angle, and gray scale inversion occurs, which reduces visibility. have In order to overcome these shortcomings, an optical retardation film (compensation film) is used in liquid crystal display devices to express the optical phase difference generated in the liquid crystal cell.

In particular, an anti-reflection retardation film is used in a polarizer applied to an organic light emitting device (OLED). The existing retardation film consists of 2 to 3 layers, and the first retardation layer uses COP or inverse dispersion PC, and +C A method of coating liquid crystal is used, or a method of using +C liquid crystal for the liquid crystal of a reverse dispersion retardation film on a zero retardation film is used.

However, in the case of using +C liquid crystal for the liquid crystal of the reverse dispersion retardation film in the zero retardation film, the retardation film itself is composed of three layers and has to go through two coating processes, which increases the manufacturing process, resulting in increased process costs and process limitations. It is difficult, and durability problems arise because the coating layer is composed of multiple layers.

Therefore, due to the above problems, research is being conducted on a retardation film for anti-reflection in a polarizer applied to an organic light emitting device (OLED), which has a simple manufacturing process, improved wavelength dispersion, and excellent durability. .

Korean Public Gazette No. 2005-0101743

The present invention seeks to provide a retardation film, a polarizing plate including the same, a liquid crystal display device including the same, and a method of manufacturing the retardation film.

An exemplary embodiment of the present application is a retardation film comprising a composition containing a (meth)acrylate-based resin or a cured product thereof. The composition has a glass transition temperature of 115°C or higher, and the retardation film has an MD of the surface of the retardation film. The angle between the (machine direction) direction and the slow axis has a value of 30° or more and 60° or less, and the retardation film satisfies the following equations (1) and (2). to provide.

Equation (1): 0.7 ≤ Rin(450)/Rin(550) ≤ 1.03

Equation (2): 0.97 ≤ Rin(650)/Rin(550) ≤ 1.2

In the above equations (1) and (2), Rin(λ) is (nx-ny) x d, and is the in-plane phase difference at the wavelength λ nm,

nx is the refractive index in the slow axis direction of the retardation film surface.

ny is the refractive index in the fast axis direction of the retardation film surface, and d is the retardation film thickness.

Another embodiment is a polarizer; And it provides a polarizing plate including at least one retardation film according to an exemplary embodiment of the present application.

In addition, an exemplary embodiment of the present application is a liquid crystal cell; an upper polarizer provided on the upper layer of the liquid crystal cell; a lower polarizer provided on the lower layer of the liquid crystal cell; and a backlight unit provided on a lower layer of the lower polarizer, wherein at least one of the upper polarizer and the lower polarizer is a polarizer; and a retardation film according to the present application disposed on one surface of the polarizer.

Finally, in an exemplary embodiment of the present application, preparing a composition of the retardation film according to the present application; Molding the retardation film by melting and extruding the composition; stretching the retardation film; And a method of manufacturing a retardation film comprising the step of obliquely stretching the retardation film, wherein the retardation film has an angle formed by the MD (machine direction) direction of the retardation film surface and the slow axis direction of 30° or more and 60°. A method for manufacturing a retardation film having the following values is provided.

The retardation film according to the present invention is a retardation film containing a composition containing a (meth)acrylate-based resin or a cured product thereof. The composition has a glass transition temperature in the range of 115 ° C. or higher, and has excellent wavelength dispersion. At the same time, it has excellent heat resistance.

In addition, the retardation film according to the present invention has an angle of 30° or more and 60° or less with the slow axis based on the MD (machine direction) direction of the retardation film surface, and has the above angle range through oblique stretching. Accordingly, the manufacturing process has the characteristic of being simplified.

In addition, the retardation film according to the present invention can adjust wavelength dispersion as the angle between the MD (machine direction) direction of the retardation film surface and the slow axis satisfies a specific range, making it possible to use it for various purposes. It has characteristics.

Figure 1 is a diagram showing a stacked structure of a polarizing plate according to an exemplary embodiment of the present application.
Figure 2 is a diagram showing a stacked structure of a polarizing plate according to an exemplary embodiment of the present application.
Figure 3 is a diagram showing a liquid crystal display device according to an exemplary embodiment of the present application.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Additionally, the embodiments of the present invention are provided to explain the present invention in more detail to those with average knowledge in the relevant technical field.

An exemplary embodiment of the present application is a retardation film comprising a composition containing a (meth)acrylate-based resin or a cured product thereof. The composition has a glass transition temperature of 115°C or higher, and the retardation film has an MD of the surface of the retardation film. The angle between the (machine direction) direction and the slow axis has a value of 30° or more and 60° or less, and the retardation film satisfies the following equations (1) and (2). to provide.

Equation (1): 0.7 ≤ Rin(450)/Rin(550) ≤ 1.03

Equation (2): 0.97 ≤ Rin(650)/Rin(550) ≤ 1.2

In the above equations (1) and (2), Rin(λ) is (nx-ny) x d, and is the in-plane phase difference at the wavelength λ nm,

nx is the refractive index in the slow axis direction of the retardation film surface.

ny is the refractive index in the fast axis direction of the retardation film surface, and d is the retardation film thickness.

The retardation film according to the present invention is a retardation film containing a composition containing a (meth)acrylate-based resin or a cured product thereof. The composition has a glass transition temperature in the range of 115 ° C. or higher, and has excellent wavelength dispersion. At the same time, it has excellent heat resistance.

In Equations 1 and 2 above, R _in (λ) is the plane direction phase difference measured at a wavelength of λnm, and is a value measured using Axoscan from Axometrics. That is, in Equations 1 and 2, R _in (450), R _in (550), and R _in (650) mean the in-plane retardation values at 450 nm, 550 nm, and 650 nm, respectively.

The plane direction retardation at each wavelength is a value determined by the difference between the refractive index in the slow axis direction and the refractive index in the fast axis direction and the thickness of the retardation film, as shown in the explanation of Equation 1 and Equation 2 above. am.

The slow axis and fast axis are determined according to the orientation direction of the polymer chain of the retardation film. The direction in which the polymer chain is highly oriented is called the slow axis, which is the direction for each wavelength. The direction in which light takes a long time to pass and has the greatest phase difference is called the slow axis. The fast axis is the opposite concept. The direction in which the polymer chain has a small orientation is called the fast axis. It takes a short time for light to pass at each wavelength, so the direction with the smallest phase difference is the fast axis. It is called the fast axis.

In an exemplary embodiment of the present application, Equation 1 may be 0.7 ≤ Rin(450)/Rin(550) ≤ 1.03, and Equation 2 may be 0.97 ≤ Rin(650)/Rin(550) ≤ 1.2.

In an exemplary embodiment of the present application, Equation 1 may be 0.7 ≤ Rin(450)/Rin(550) ≤ 0.99, and Equation 2 may be 0.97 ≤ Rin(650)/Rin(550) ≤ 1.01.

In Equation 1, the in-plane retardation at a wavelength of 550 nm can be referred to as R _in (550), and the in-plane retardation at a wavelength of 450 nm can be referred to as R _in (450). The phase difference ratio at the two wavelengths, R _in (450)/R _in (550), is 1.03 or less, and in Equation 2, R _in (650)/R _in (550) falls within the entire range of Equation 2. If satisfied, reverse wavelength/flat wavelength dispersion can be implemented, and since the retardation film of the present invention has reverse wavelength dispersion in which the phase delay value increases as the optical wavelength increases, the phase is relatively uniform in a wide optical band. It is characterized by causing a delay. As a result, when the retardation film of the present invention is applied to a polarizer or display device, superior color, visibility, and optical characteristics can be realized compared to the prior art.

In this specification, the glass transition temperature was measured using METTLER's DSC (Differential Scanning Calorymeter) equipment, and the measurement method was to put 3 mg to 20 mg of the resin to be measured into an aluminum crucible and heat it at 10 ° C per minute from 30 ° C to 250 ° C. The resin is melted at a temperature increase rate, cooled again to 30°C, and then melted again at a temperature increase rate of 10°C per minute to 200°C. At this time, through METTLER's DSC equipment, the midpoint of the temperature range where the specific heat behavior of the resin changes heat during the second melting process is measured, and this value is measured as the glass transition temperature. That is, the glass transition temperature of a monomer may be a value measured by measuring the glass transition temperature of a monomer when a single monomer is polymerized to form a monopolymer.

In the present application, the composition and content contained in the retardation film can be confirmed through nuclear magnetic resonance (NMR) analysis.

In an exemplary embodiment of the present application, a shock absorber on one or both sides of the retardation film; and a skin layer containing a (meth)acrylate-based resin having a glass transition temperature of 100°C or higher.

In the case of the skin layer, even if the glass transition temperature of the (meth)acrylate-based resin included is low, the stretching temperature is adjusted to that of the core layer, thereby lowering the phase difference and increasing thermal stability.

The core layer refers to a retardation film without a skin layer.

In one embodiment of the present application, rubber may be used as the shock absorber.

In an exemplary embodiment of the present application, the shock absorber is 10 parts by weight or more and 35 parts by weight or less, preferably 15 parts by weight or more and 30 parts by weight, based on 100 parts by weight of the (meth)acrylate resin having a glass transition temperature of 100 ℃ or higher. parts or less, more preferably 17 parts by weight or more and 30 parts by weight or less.

In an exemplary embodiment of the present application, the (meth)acrylate-based resin having a glass transition temperature of 100°C or higher may be polymethylmethacrylate (PMMA).

In an exemplary embodiment of the present application, the composition of the retardation film includes a retardation regulator; and a triazine-based birefringence adjuster, wherein the triazine-based birefringence adjuster satisfies the following equation (3).

Equation (3): dichroism = |αe-α ₀ |

In the above equation (3), αe is the extinction coefficient of extraordinary ray, and α ₀ is the extinction coefficient of ordinary light (ordinary ray).

In Equation 3, the extinction coefficient α _e of the extraordinary ray and the extinction coefficient α ₀ of the ordinary ray can be calculated by measuring the polarized light transmittance of the film containing the birefringence regulator. For example, a polarizer is attached to the light source of a transmittance measuring device (e.g., Hitachi's U-3310, etc.) to generate polarized light, and then the polarized light is transmitted through a sample film to measure the transmittance T _o of normal light. , transmit polarized light while rotating the sample film by 90° to measure the transmittance T _e of the unusual light. Then, the absorption coefficients of the normal light and the unusual light can be calculated by substituting the measured normal light transmittance and the unusual light transmittance into the equation below.

-Log T = αbc

(T: transmittance, α: extinction coefficient, b: sample thickness, c: triazine birefringence regulator concentration)

In an exemplary embodiment of the present application, the composition of the retardation film may have a glass transition temperature of 115°C or higher, preferably 116°C or higher, and more preferably 118°C or higher.

In another embodiment, the composition of the retardation film may have a glass transition temperature of 150°C or lower, preferably 140°C or lower, and more preferably 135°C or lower.

The retardation film according to the present application has particularly excellent heat resistance as the core layer includes a composition having the above glass transition temperature range.

In an exemplary embodiment of the present application, the phase difference adjusting agent is styrene-maleic anhydride (SMA); Alternatively, a retardation film that is a copolymer of styrene-acrylonitrile (SAN) is provided.

The product obtained by polymerizing two or more different types of units is called a copolymer, and the copolymer may have two or more types of units arranged irregularly or regularly.

The copolymer is a random copolymer in which monomers are mixed together without regularity, a block copolymer in which blocks arranged in certain sections are repeated, or an alternating copolymer in which monomers are alternately repeated and polymerized. There may be a copolymer (Alternating Copolymer), and the phase difference adjuster according to an exemplary embodiment of the present application may be a random copolymer, a block copolymer, or an alternating copolymer.

In the case of the retardation film according to the present application, in order to satisfy the above glass transition temperature range, styrene-maleic anhydride (SMA), which has a high glass transition temperature, is included as a retardation regulator in the (meth)acrylate resin. Alternatively, a highly heat-resistant (meth)acrylate-based resin with a high glass transition temperature may contain styrene-acrylonitrile (SAN) as a phase difference regulator, thereby satisfying the glass transition temperature in the above range. , it is possible to produce a retardation film with particularly excellent heat resistance.

In an exemplary embodiment of the present application, the retardation film is provided in an amount of 10 parts by weight or more and 85 parts by weight or less, based on 100 parts by weight of the composition of the retardation film.

In another embodiment, the retardation regulator is present in an amount of 10 parts by weight or more and 85 parts by weight or less, preferably 15 parts by weight or more and 85 parts by weight or less, more preferably 15 parts by weight, based on 100 parts by weight of the composition of the retardation film. It may be more than 80 parts by weight or less.

When the phase difference adjuster is included in the above range, the retardation film has the feature of changing the wavelength dispersion to an appropriate range to implement reverse wavelength/flat wavelength dispersion. In addition, when the content of the retardation regulator exceeds the above range of parts by weight, the glass transition temperature of the retardation film composition is lowered, which may have the disadvantage of poor heat resistance.

In an exemplary embodiment of the present application, the birefringence regulator is provided in an amount of 5 parts by weight or more and 40 parts by weight or less based on 100 parts by weight of the composition of the retardation film.

In another embodiment, the birefringence regulator is present in an amount of 5 parts by weight or more and 40 parts by weight or less, preferably 5.5 parts by weight or more and 35 parts by weight or less, more preferably 6 parts by weight, based on 100 parts by weight of the composition of the retardation film. It may be more than 30 parts by weight or less.

In the present application, the triazine-based birefringence regulator included in the retardation film is not used for general UV blocking purposes, but is intended to change wavelength dispersion by using the difference in refractive index with the acrylic resin.

When the triazine-based birefringence regulator is included in the above content range, the wavelength dispersion of the retardation film can be lowered below a certain range to achieve normal/inverse dispersion from general positive dispersion, and has excellent optical properties.

In an exemplary embodiment of the present application, the (meth)acrylate-based resin may include a (meth)acrylate-based resin having a weight average molecular weight of 100,000 g/mol to 5 million g/mol.

The weight average molecular weight is one of the average molecular weights used as a standard for the molecular weight of certain polymer materials whose molecular weight is not uniform, and is a value obtained by averaging the molecular weights of the component molecular species of a polymer compound with a molecular weight distribution by weight fraction.

The weight average molecular weight can be measured through Gel Permeation Chromatography (GPC) analysis.

In this specification, (meth)acrylate is meant to include both acrylate and methacrylate. For example, the (meth)acrylate-based resin may be a copolymer of a (meth)acrylic acid ester-based monomer and a crosslinkable functional group-containing monomer.

The (meth)acrylic acid ester-based monomer is not particularly limited, but examples include alkyl (meth)acrylate. More specifically, monomers having an alkyl group having 1 to 12 carbon atoms include pentyl (meth)acrylate, n-butyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethyl It may include one or more of hexyl (meth)acrylate, dodecyl (meth)acrylate, and decyl (meth)acrylate.

The crosslinkable functional group-containing monomer is not particularly limited, but may include, for example, one or more of a hydroxy group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer.

Examples of the hydroxyl group-containing compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. ) acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, or 2-hydroxypropylene glycol (meth)acrylate.

Examples of the carboxyl group-containing compounds include (meth)acrylic acid, 2-(meth)acryloyloxyacetic acid, 3-(meth)acryloyloxypropylic acid, 4-(meth)acryloyloxybutylic acid, and acrylic acid. Examples include sieve, itaconic acid, maleic acid, or maleic anhydride.

Examples of the nitrogen-containing monomer include (meth)acrylonitrile, N-vinyl pyrrolidone, or N-vinyl caprolactam.

The (meth)acrylate-based resin may also be copolymerized with at least one of vinyl acetate, styrene, and acrylonitrile from the viewpoint of improving other functionalities such as compatibility.

In an exemplary embodiment of the present application, the (meth)acrylate-based resin is polymethylmethacrylate (PMMA), or is selected from the group consisting of an N-substituted maleimide structure, a lactone ring structure, and a glutarimide structure. Provided is a retardation film having one or more monomers in the acrylate molecular chain.

In an exemplary embodiment of the present application, the (meth)acrylate-based resin may be polymethyl methacrylate (PMMA, poly methyvlmethacrylate).

When the (meth)acrylate resin has polymethyl methacrylate (PMMA), styrene-maleic anhydride (SMA) may be used as the retardation regulator to improve the heat resistance of the retardation film. You can.

In an exemplary embodiment of the present application, the (meth)acrylate-based resin has one or more monomers selected from the group consisting of an N-substituted maleimide structure, a lactone ring structure, and a glutarimide structure in the acrylate molecular chain. It may be a (meth)acrylate-based resin.

When the (meth)acrylate-based resin has one or more monomers selected from the group consisting of N-substituted maleimide structure, lactone ring structure, and glutarimide structure in the acrylate molecular chain. , (meth)acrylate resin itself has excellent heat resistance.

In the (meth)acrylate-based resin, the N-substituted maleimide structure, lactone ring structure, and glutarimide structure can be confirmed through nuclear magnetic resonance (NMR) measurement.

In an exemplary embodiment of the present application, the N-substituted maleimide structure may be N-phenylmaleimide (PMI).

In an exemplary embodiment of the present application, the birefringence regulator may be a 2-hydroxyphenyl-s-triazine derivative, and specifically, BASF's Tinuvin 1600, Tinuvin 460, and Tinuvin477. , Tinuvin479, Tinuvin1577, and/or ADEKA's LA-F70, LA46, etc., but are not limited thereto.

In an exemplary embodiment of the present application, the birefringence adjusting agent may be represented by the following formula (1).

[Formula 1]

In Formula 1,

L ₁ to L ₃ are the same or different from each other, and are each independently directly bonded; Substituted or unsubstituted arylene group; Or a substituted or unsubstituted heteroarylene group,

Z ₁ to Z ₃ are the same as or different from each other, and are each independently hydrogen; hydroxyl group; Substituted or unsubstituted alkoxy group; Substituted or unsubstituted alkyl group; Substituted or unsubstituted aryl group; Or a substituted or unsubstituted heteroaryl group.

a, b, and c are the same or different from each other and are each independently an integer of 1 to 3,

p, q and r are the same or different from each other and are each independently an integer from 1 to 5. When a, b, c, p, q and r are integers of 2 or more, 2 or more substituents in parentheses are the same or different from each other.

Examples of the above substituents are described below, but are not limited thereto.

In this specification, the term “substituted or unsubstituted” refers to an alkoxy group; Alkyl group; Aryl group; and substituted or unsubstituted with one or more substituents selected from the group consisting of heterocyclic groups, or substituted or unsubstituted with two or more of the above-exemplified substituents linked. For example, “a substituent group in which two or more substituents are connected” may be a biphenyl group. That is, the biphenyl group may be an aryl group, or it may be interpreted as a substituent in which two phenyl groups are connected.

In the present specification, the alkyl group may be straight chain or branched, and the number of carbon atoms is not particularly limited, but is preferably 1 to 40. According to one embodiment, the carbon number of the alkyl group is 1 to 20. According to another embodiment, the carbon number of the alkyl group is 1 to 10. According to another embodiment, the carbon number of the alkyl group is 1 to 6. Specific examples of alkyl groups include methyl group, ethyl group, propyl group, n-propyl group, isopropyl group, butyl group, n-butyl group, isobutyl group, tert-butyl group, sec-butyl group, 1-methyl-butyl group, 1-ethyl-butyl group, pentyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, hexyl group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group, 4- Methyl-2-pentyl group, 3,3-dimethylbutyl group, 2-ethylbutyl group, heptyl group, n-heptyl group, 1-methylhexyl group, cyclopentylmethyl group, cyclohexylmethyl group, octyl group, n-octyl group , tert-octyl group, 1-methylheptyl group, 2-ethylhexyl group, 2-propylpentyl group, n-nonyl group, 2,2-dimethylheptyl group, 1-ethyl-propyl group, 1,1-dimethyl- Propyl group, isohexyl group, 4-methylhexyl group, 5-methylhexyl group, etc., but are not limited to these.

In the present specification, the alkoxy group may be straight chain, branched chain, or ring chain. The number of carbon atoms of the alkoxy group is not particularly limited, but is preferably 1 to 40 carbon atoms. Specifically, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentyloxy, neopentyloxy, isopentyloxy, n. -It can be hexyloxy, 3,3-dimethylbutyloxy, 2-ethylbutyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, benzyloxy, p-methylbenzyloxy, etc. It is not limited.

Substituents containing alkyl groups, alkoxy groups, and other alkyl group moieties described in this specification include both straight-chain or branched forms.

In the present specification, the aryl group is not particularly limited, but preferably has 6 to 60 carbon atoms, and may be a monocyclic aryl group or a polycyclic aryl group. According to one embodiment, the aryl group has 6 to 30 carbon atoms. According to one embodiment, the aryl group has 6 to 20 carbon atoms. The aryl group may be a monocyclic aryl group, such as a phenyl group, biphenyl group, or terphenyl group, but is not limited thereto. The polycyclic aryl group may be a naphthyl group, anthracenyl group, phenanthryl group, pyrenyl group, perylenyl group, triphenyl group, chrysenyl group, fluorenyl group, etc., but is not limited thereto.

In the present specification, the heterocyclic group is a heterocyclic group containing one or more of N, O, P, S, Si, and Se as heteroatoms, and the number of carbon atoms is not particularly limited, but is preferably 1 to 60 carbon atoms. According to one embodiment, the carbon number of the heterocyclic group is 1 to 30. Examples of heterocyclic groups include pyridyl group, pyrrole group, pyrimidyl group, pyridazinyl group, furanyl group, thiophenyl group, imidazole group, pyrazole group, oxazole group, isoxazole group, thiazole group, isothiazole group, Triazole group, oxadiazole group, thiadiazole group, dithiazole group, tetrazole group, pyranyl group, thiopyranyl group, pyrazinyl group, oxazinyl group, thiazinyl group, dioxynyl group, triazinyl group, tetrazinyl group, quinine Nolinyl group, isoquinolinyl group, quinolyl group, quinazolinyl group, quinoxalinyl group, naphthyridinyl group, acridyl group, xanthenyl group, phenanthridinyl group, diazanaphthalenyl group, triazidenyl group, indole group , indolinyl group, indolizinyl group, phthalazinyl group, pyrido pyrimidinyl group, pyrido pyrazinyl group, pyrazino pyrazinyl group, benzothiazole group, benzoxazole group, benzimidazole group, benzothiophene group. , benzofuranyl group, dibenzothiophenyl group, dibenzofuranyl group, carbazole group, benzocarbazole group, dibenzocarbazole group, indolocarbazole group, indenocarbazole group, phenazinyl group, imidazopyridine group, phenoxazinyl group. , phenanthridine group, phenanthroline group, phenothiazine group, imidazopyridine group, imidazophenanthridine group. A benzoimidazoquinazoline group, a benzoimidazophenanthridine group, etc. are included, but are not limited to these.

In the present specification, the description of the heterocyclic group described above can be applied, except that the heteroaryl group is aromatic.

In this specification, the description of the aryl group described above can be applied, except that arylene is a divalent group.

In an exemplary embodiment of the present application, L ₁ to L ₃ are a direct bond; Alternatively, it may be a substituted or unsubstituted arylene group having 6 to 60 carbon atoms.

In another exemplary embodiment, L ₁ to L ₃ are a direct bond; Alternatively, it may be a substituted or unsubstituted arylene group having 6 to 40 carbon atoms.

In another exemplary embodiment, L ₁ to L ₃ are a direct bond; Or it may be a phenylene group.

In an exemplary embodiment of the present application, Z ₁ to Z ₃ are hydrogen; hydroxyl group; A substituted or unsubstituted aryl group having 6 to 60 carbon atoms; Or it may be a substituted or unsubstituted alkoxy group.

In another exemplary embodiment, Z ₁ to Z ₃ are hydrogen; hydroxyl group; A substituted or unsubstituted aryl group having 6 to 40 carbon atoms; Or it may be a substituted or unsubstituted alkoxy group.

In another exemplary embodiment, Z ₁ to Z ₃ are hydrogen; hydroxyl group; Aryl group having 6 to 40 carbon atoms; Alternatively, it may be an alkoxy group substituted or unsubstituted with an alkyl group having 1 to 40 carbon atoms.

In another exemplary embodiment, Z ₁ to Z ₃ are hydrogen; hydroxyl group; phenyl group; It may be a substituted or unsubstituted alkoxy group with a branched chain alkyl group having 1 to 10 carbon atoms.

In an exemplary embodiment of the present application, Formula 1 may be represented by Formula 2 below.

[Formula 2]

In Formula 2, the definitions of Z ₁ to Z ₃ , p, q, and r are the same as those in Formula 1.

In an exemplary embodiment of the present application, at least one of Z ₁ to Z ₃ may be a substituted or unsubstituted aryl group.

In particular, when at least one of Z ₁ to Z ₃ has a phenyl group, the difference in birefringence appears larger than when it does not, and due to the structural difference in the birefringence regulator, the birefringence regulator in which Z ₁ to Z ₃ does not have a phenyl group is used. Even when prescribed in large quantities, the effect appears to be small.

In particular, in one embodiment of the present application, when BASF's Tinuvin 1600 (2-hydroxyphenyl-s-triazine derivative) was used as a birefringence adjuster, the effect of improving wavelength dispersion was the greatest compared to similar contents, which was due to the structural difference. This may be due to a difference in birefringence.

In an exemplary embodiment of the present application, the retardation film satisfies the following equations 4 and 5.

[Equation 4]

50nm ≤ R _in (550) ≤ 250nm

[Equation 5]

50nm ≤ R _th (550) ≤ 350nm

In Equations 4 and 5 above,

R _in (550) is the in-plane phase difference at a wavelength of 550 nm, and is the value of (n _x -n _y ) xd,

R _th (550) is the thickness direction phase difference at a wavelength of 550 nm, and is the value of {n _z -(n _x +n _y )/2} xd,

The n _x is the refractive index in the slow axis direction of the retardation film surface,

The n _y is the refractive index in the fast axis direction of the retardation film surface,

where n _z is the refractive index in the thickness direction of the retardation film,

Where d is the thickness of the retardation film.

In Equations 4 and 5 above, R _in (λ) is the plane direction phase difference measured at a wavelength of λ nm, and is a value measured using Axoscan from Axometrics. In addition, R _th (λ) is the phase difference in the thickness direction at a wavelength of λ nm, and the refractive index in the thickness direction is measured with AxoScan equipment, and is a value determined by the difference from the average of the refractive index in the plane direction and the thickness.

In an exemplary embodiment of the present application, the thickness of the retardation film is 10 ㎛ or more and 120 ㎛ It may be below.

In another embodiment, the thickness of the retardation film is 10 ㎛ or more and 120 ㎛ or less, preferably 30 ㎛ or more and 110 ㎛ or less, more preferably 60 ㎛ or more and 105 ㎛ It may be below.

As can be seen from Equations 4 and 5 above, the retardation value changes depending on the thickness of the retardation film, and in the present application, when the thickness of the retardation film is within the above range, it has average dispersion/inverse dispersion.

In an exemplary embodiment of the present application, preparing a composition of the retardation film according to the present application; Molding the retardation film by melting and extruding the composition; stretching the retardation film; And a method of manufacturing a retardation film comprising the step of obliquely stretching the retardation film, wherein the retardation film has an angle formed by the MD (machine direction) direction of the retardation film surface and the slow axis direction of 30° or more and 60°. A method for manufacturing a retardation film having the following values is provided.

In an exemplary embodiment of the present application, a method of manufacturing a retardation film is provided, wherein the step of stretching the retardation film is a step of stretching the retardation film in the MD (machine direction) direction of the surface of the retardation film.

In one aspect of the present application, the step of obliquely stretching the retardation film is performed so that the acute angle formed between the direction of stretching the retardation film and the oblique stretching direction of the retardation film is 30° or more and 60° or less. A manufacturing method is provided.

That is, in the method of manufacturing the retardation film, the retardation film may be manufactured through melting and extrusion, followed by stretching in the MD direction, followed by an oblique stretching step. At this time, the angle of the acute angle of the straight line connecting the moving direction of the inclined stretching machine and the moving direction of the MD stretching machine is called the tilt angle, and by adjusting this, the MD (machine direction) direction of the retardation film surface is aligned with the slow axis. It can be manufactured to have an angle of 30° or more and 60° or less.

In an exemplary embodiment of the present application, the angle formed by the MD (machine direction) direction of the retardation film surface and the slow axis is 30° or more and 60° or less, preferably a value of 35° or more and 55° or less. You can have

The retardation film according to the present invention is capable of controlling wavelength dispersion as the angle between the MD (machine direction) direction of the retardation film surface and the slow axis satisfies a certain range, making it possible to use it for various purposes. have it

Meanwhile, the method for producing the retardation film of the present invention having the above characteristics is not particularly limited, and may be produced by preparing the composition, forming it into a film, and stretching it.

The composition is prepared by pre-blending the film raw materials using any suitable mixer, such as an omni mixer, and then extruding and kneading the resulting mixture. In this case, the mixer used for extrusion kneading is not particularly limited, and for example, any suitable mixer such as an extruder such as a single-screw extruder or a twin-screw extruder or a pressure kneader can be used.

Examples of the film forming method include any appropriate film forming method such as solution casting method (solution casting method), melt extrusion method, calendering method, and compression molding method. Among these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are preferable.

Solvents used in the solution casting method (solution casting method) include, for example, aromatic hydrocarbons such as benzene, toluene, and xylene; Aliphatic hydrocarbons such as cyclohexane and decalin; esters such as ethyl acetate and butyl acetate; Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; Halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride; dimethylformamide; Dimethyl sulfoxide, etc. can be mentioned. These solvents may be used individually or two or more types may be used in combination.

Equipment for carrying out the solution casting method (solution casting method) includes, for example, a drum casting machine, a band casting machine, and a spin coater. Meanwhile, examples of the melt extrusion method include the T die method and the inflation method. The molding temperature may be 150°C to 350°C, or 200°C to 300°C.

When forming a film by the T die method, a T die can be mounted on the tip of a known single-screw extruder or a twin-screw extruder, and the extruded film is wound to obtain a roll-shaped film.

After the film is formed through the above process, the film is stretched. The stretching process may be performed in machine direction (MD) stretching, transverse direction (TD) stretching, or both. Additionally, when both longitudinal stretching and transverse stretching are performed, either one may be stretched first and then stretched in the other direction, or both directions may be stretched simultaneously. Additionally, the stretching may be performed in one step or may be performed in multiple steps. In the case of longitudinal stretching, stretching can be performed by a speed difference between rolls, and in the case of transverse stretching, a tenter can be used. The tenter's rail starting angle is usually within 10 degrees to suppress the bowing phenomenon that occurs during transverse stretching and to regularly control the angle of the optical axis. The bowing suppression effect can be obtained even when transverse stretching is performed in multiple stages.

The stretching temperature is preferably in the range near the glass transition temperature of the composition as a film raw material. When the glass transition temperature of the composition is Tg, it is preferably (Tg-30°C) to (Tg+100°C). Preferably, it is within the range of (Tg-20°C) to (Tg+80°C), more preferably within the range of (Tg-5°C) to (Tg+20°C). If the stretching temperature is less than (Tg-30°C), there is a risk that a sufficient stretching ratio may not be obtained. Conversely, if the stretching temperature exceeds (Tg+100°C), the resin composition may flow and there is a risk that stable stretching may not be performed.

Additionally, in an exemplary embodiment of the present application, the stretching ratio in the step of stretching the film may be 1.05 to 10 times based on the length in the stretching direction.

In addition, the total stretching ratio may be 1.1 times or more, 1.2 times or more, or 1.5 times or more, and 25 times or less, 10 times or less, or 7 times or less based on the total stretched area of the base film. If the stretching ratio is less than 1.1 times, the stretching effect may not be sufficiently achieved, and if it exceeds 25 times, the film layer may crack.

Before the stretching, the surface on which the composition is applied may be flattened and a drying process may be further performed to volatilize the solvent contained in the composition.

The retardation film may be subjected to heat treatment (annealing) after stretching treatment in order to stabilize its optical isotropy or mechanical properties. The heat treatment conditions are not particularly limited and any appropriate conditions known to those skilled in the art may be employed.

The retardation film of the present invention as described above can be usefully applied to a polarizing plate and/or a liquid crystal display device. In one embodiment of the present invention, the present invention includes a polarizer; And it provides a polarizing plate including at least one retardation film of the present application.

Figure 1 is a diagram showing a stacked structure of a polarizer 103 according to an exemplary embodiment of the present application. Specifically, the polarizer 103 has a structure in which a polarizer 102 and a retardation film 101 are stacked on one surface of the polarizer.

In an exemplary embodiment of the present application, the polarizer is not particularly limited, and a polarizer well known in the art, for example, a film made of polyvinyl alcohol (PVA) containing iodine or a dichroic dye, is used.

A polarizer exhibits the characteristic of being able to extract only light vibrating in one direction from light that is incident while vibrating in various directions. These properties can be achieved by stretching polyvinyl alcohol (PVA), which has absorbed iodine, under strong tension. For example, more specifically, swelling the PVA film by soaking it in an aqueous solution, dyeing the swollen PVA film with a dichroic material that imparts polarization, and stretching the dyed PVA film. ) to form a polarizer through a stretching step of arranging the dichroic dye material side by side in the stretching direction, and a complementary color step of correcting the color of the PVA film that has undergone the stretching step. However, the polarizing plate of the present invention is not limited to this.

In an exemplary embodiment of the present application, the polarizer and the retardation film can be adhered with an adhesive, and the adhesive that can be used is not particularly limited as long as it is known in the art. For example, there are water-based adhesives, one-component or two-component polyvinyl alcohol (PVA)-based adhesives, polyurethane-based adhesives, epoxy-based adhesives, styrene butadiene rubber (SBR-based) adhesives, or hot melt adhesives, but the present invention It is not limited to these examples.

The retardation film may be directly attached to one or both sides of the polarizer. In addition, it can be usefully used as a retardation film by attaching it to the protective film of a conventional polarizer in which a protective film is attached to both sides of the polarizer.

When the retardation film is directly attached to one or both sides of the polarizer, for example, the structure may be an upper protective film/polarizer/retardation film or a retardation film/polarizer/lower protective film. The attachment method is to coat the surface of the retardation film or polarizer with a primer using a roll coater, gravure coater, bar coater, knife coater, capillary coater, or micro chamber doctor blade coater. , it can be performed by spraying adhesive in a dropwise manner, heating and lamination of the laminate including the retardation film and polarizer with a lamination roll, lamination by pressing at room temperature, or UV curing.

Figure 2 is a diagram showing a stacked structure of a polarizing plate according to an exemplary embodiment of the present application. Specifically, the polarizer 103 may have a structure in which the polarizer protection film 104/adhesive layer 105/retardation film 101/polarizer 102/polarizer protection film 104 are stacked in that order.

In one embodiment of the present application, a polarizer protective film is attached to one side of the polarizer, and a retardation film according to the present application is attached to the opposite side of the polarizer to which the polarizer protective film is attached. do.

In an exemplary embodiment of the present application, the polarizer protective film includes a cycloolefin polymer (COP)-based film, an acrylic film, a triacetylcellulose (TAC)-based film, a cycloolefin copolymer (COC)-based film, a polynorbornene (PNB)-based film, and a polyethylene (PET)-based film. It may be made of any one or more of terephtalate-based films.

In an exemplary embodiment of the present application, a liquid crystal display device including the polarizer is provided.

In addition, an exemplary embodiment of the present application is a liquid crystal cell; an upper polarizer provided on the upper layer of the liquid crystal cell; a lower polarizer provided on the lower layer of the liquid crystal cell; and a backlight unit provided on a lower layer of the lower polarizer, wherein at least one of the upper polarizer and the lower polarizer is a polarizer; and a retardation film according to an exemplary embodiment of the present application disposed on one surface of the polarizer.

In an exemplary embodiment of the present application, the upper polarizer includes the polarizer; and the retardation film, wherein the retardation film is disposed to face the liquid crystal cell.

In an exemplary embodiment of the present application, the lower polarizer includes the polarizer; and the retardation film, wherein the retardation film is disposed to face the backlight unit.

The upper polarizer includes the polarizer; and the retardation film, wherein the retardation film is disposed to face the liquid crystal cell, wherein the upper polarizer includes the polarizer; and the retardation film, which means that the retardation film at this time is arranged in the direction of the liquid crystal cell within the liquid crystal display device. Specifically, the backlight unit/lower polarizer/liquid crystal cell/retardation film/polarizer are stacked in that order. It means having a structure.

The lower polarizer includes the polarizer; and the retardation film, wherein the retardation film is disposed to face the backlight unit, wherein the lower polarizer includes the polarizer; and the retardation film, which means that the retardation film at this time is disposed in the backlight unit direction within the liquid crystal display device, and specifically, backlight unit/polarizer/retardation film/liquid crystal cell/upper polarizer are stacked in that order. It means having a structure.

In the liquid crystal display device according to the present application, when the retardation film among the upper polarizers is disposed to face the liquid crystal cell, or when the retardation film among the lower polarizers is disposed to face the backlight unit, it is included in the retardation film. The triazine-based birefringence regulator may have the main purpose of improving the function of the panel through a phase contrast expression function rather than UV absorption as the main function.

The backlight unit includes a light source that irradiates light from the back of the liquid crystal panel. The type of the light source is not particularly limited, and general LCD light sources such as CCFL, HCFL, or LED can be used.

Figure 3 is a diagram showing a liquid crystal display device according to an exemplary embodiment of the present application. Specifically, an upper polarizer 11 and a lower polarizer 12 may be stacked on both sides of the liquid crystal cell 10, and the surface of the lower polarizer 12 adjacent to the backlight unit 14 is in contact with the liquid crystal cell 10. It may have a structure in which a protective film 13 is laminated on the opposite side. A polarizer according to an embodiment of the present application may be used as the upper polarizer 11 and the lower polarizer 12, and preferably, a polarizer according to an embodiment of the present application may be used as the lower polarizer 12.

The contents of the protective film are the same as those of the polarizer protective film described above.

Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, these examples are merely presented as examples of the invention, and the scope of the invention is not determined by them.

< Manufacturing example >

< phase difference Production of film>

A retardation film was produced by melting and extruding the retardation film composition having the composition shown in Table 1 below, and then stretched in the MD direction according to the conditions shown in Table 1 below. Afterwards, a retardation film was produced by adjusting the acute angle (tilt angle) of the straight line connecting the direction of movement of the inclined stretcher and the direction of MD stretcher according to the conditions in Table 1 below.

As can be seen in Table 1, the retardation film corresponding to Examples 1 to 4 is a retardation film containing a composition containing a (meth)acrylate resin or a cured product thereof, and the composition of the core layer has a glass transition temperature. As it has a range of 115℃ or higher, it has excellent wavelength dispersion and has excellent heat resistance.

The retardation film corresponding to Example 4 was manufactured by improving mechanical properties using a skin layer using co-extrusion in order to use SMA with a high glass transition temperature alone.

In addition, the retardation film according to the present invention has an angle of 30° or more and 60° or less with the slow axis based on the MD (machine direction) direction of the retardation film surface, and has the above angle range through oblique stretching. Accordingly, it was confirmed that the manufacturing process has the characteristic of being simplified.

In addition, the retardation film according to the present invention can adjust wavelength dispersion as the angle between the MD (machine direction) direction of the retardation film surface and the slow axis satisfies a specific range, making it possible to use it for various purposes. It was confirmed that the characteristic was present.

Comparative Example 1 of Table 1 did not satisfy the inclination angle range in oblique stretching, so the retardation film had an angle formed by the MD (machine direction) direction of the retardation film surface and the slow axis with a value of 27°. In this case, in the case of Comparative Example 2, the birefringence regulator is not included, so it does not satisfy the range of Equations 1 and 2, and in the case of Comparative Example 3, the glass transition temperature value of the retardation film composition is low, confirming that the heat resistance is poor. I was able to.

101: Phase contrast film
102: Polarizer
103: Polarizer
104: Polarizer protective film
105: Adhesive layer
10: liquid crystal cell
11: upper polarizer
12: lower polarizer
13: Protective film
14: Backlight unit

Claims (17)

A retardation film containing a composition containing a (meth)acrylate resin or a cured product thereof,
The composition has a glass transition temperature of 115°C or higher,
The retardation film has an angle between the MD (machine direction) direction of the retardation film surface and the slow axis of 30° or more and 60° or less,
The retardation film satisfies the following equations (1) and (2):
Equation (1): 0.7 ≤ Rin(450)/Rin(550) ≤ 1.03
Equation (2): 0.97 ≤ Rin(650)/Rin(550) ≤ 1.2
In the above equations (1) and (2), Rin(λ) is (nx-ny)xd, and is the in-plane phase difference at the wavelength λ nm,
nx is the refractive index in the slow axis direction of the retardation film surface.
ny is the refractive index in the fast axis direction of the retardation film surface, and d is the retardation film thickness. In claim 1,
A shock absorber on one or both sides of the retardation film; And a retardation film comprising a skin layer containing a (meth)acrylate-based resin having a glass transition temperature of 100°C or higher. In claim 1,
The composition includes a phase difference regulator; And it further includes a triazine-based birefringence regulator,
The retardation film wherein the triazine-based birefringence regulator satisfies the following equation (3):
Equation (3): dichroism = |αe-α ₀ |
In the above equation (3), αe is the extinction coefficient of extraordinary ray, and α ₀ is the extinction coefficient of ordinary light (ordinary ray). In claim 3,
The phase difference adjusting agent includes styrene-maleic anhydride (SMA); Or a retardation film that is a copolymer of styrene-acrylonitrile (SAN). In claim 3,
The phase difference regulator is based on 100 parts by weight of the composition,
A retardation film containing 10 parts by weight or more and 85 parts by weight or less. In claim 3,
The triazine-based birefringence regulator is based on 100 parts by weight of the composition,
A retardation film containing 5 parts by weight or more and 40 parts by weight or less. The method according to claim 1, wherein the (meth)acrylate-based resin is polymethylmethacrylate (PMMA), or one or more monomers selected from the group consisting of an N-substituted maleimide structure, a lactone ring structure, and a glutarimide structure. A retardation film having in the acrylate molecular chain. In claim 1,
The retardation film is a retardation film that satisfies the following Equations 4 and 5:
[Equation 4]
50nm ≤ R _in (550) ≤ 250nm
[Equation 5]
50nm ≤ R _th (550) ≤ 350nm
In Equations 4 and 5 above,
R _in (550) is the in-plane phase difference at a wavelength of 550 nm, the value of (n _x -n _y ) xd,
R _th (550) is the thickness direction phase difference at a wavelength of 550 nm, and is the value of {n _z -(n _x +n _y )/2} xd,
The n _x is the refractive index in the slow axis direction of the retardation film surface,
The n _y is the refractive index in the fast axis direction of the retardation film surface,
where n _z is the refractive index in the thickness direction of the retardation film,
Where d is the thickness of the retardation film. In claim 1,
The thickness of the retardation film is 10 ㎛ or more and 100 ㎛ The retardation film is as follows. polarizer; and
A polarizing plate comprising at least one retardation film according to any one of claims 1 to 9. In claim 10,
A polarizer protective film is attached to one side of the polarizer,
A polarizing plate wherein the retardation film is attached to a surface of the polarizer opposite to the surface of the polarizer to which the polarizer protective film is attached. liquid crystal cell;
an upper polarizer provided on the upper layer of the liquid crystal cell;
a lower polarizer provided on the lower layer of the liquid crystal cell; and
It includes a backlight unit provided on a lower layer of the lower polarizer,
At least one of the upper polarizer and the lower polarizer is a polarizer; And a liquid crystal display device comprising the retardation film of any one of claims 1 to 9 disposed on one surface of the polarizer. In claim 12,
The upper polarizer includes the polarizer; And it includes the retardation film,
The retardation film is arranged to face the liquid crystal cell. In claim 12,
The lower polarizer includes the polarizer; And it includes the retardation film,
The retardation film is arranged to face the backlight unit. Preparing a composition of the retardation film according to any one of claims 1 to 9;
Molding the retardation film by melting and extruding the composition;
stretching the retardation film; and
Obliquely stretching the retardation film;
A method for manufacturing a retardation film comprising,
The retardation film is a method of manufacturing a retardation film, wherein the angle formed between the MD (machine direction) direction of the retardation film surface and the slow axis has a value of 30° or more and 60° or less. In claim 15,
The step of stretching the retardation film is a step of stretching the retardation film in the MD (machine direction) direction of the surface of the retardation film. In claim 15,
In the step of obliquely stretching the retardation film, the acute angle formed between the direction of stretching the retardation film and the oblique stretching direction of the retardation film is 30° or more and 60° or less.