KR20200027372A - Transmission Variable Device - Google Patents

Abstract

The present application relates to a device with variable transmittance. In the present application, provided is the device with variable transmittance, which does not cause problems such as crosstalk, rainbow, mirroring, or the like, while having excellent transmittance characteristics, so as to be applied to various uses. The device with variable transmittance comprises: a retardation film having an in-plane retardation of 5,000 nm or more for light having a wavelength of 550 nm; a liquid crystal alignment film; and a liquid crystal layer capable of implementing a twist alignment mode.

Description

Transmission Variable Device

The present application relates to a variable transmission device.

A device capable of varying the transmittance of a liquid crystal compound or the like is known. For example, Patent Document 1, a liquid crystal host material (Liquid Crystal Host material) and a dichroic dye guest (dichroic dye guest) is applied to the so-called GH cell (Guest host cell) variable transmittance device is known.

The use of such devices is gradually expanding, for example, the devices are eyewear such as glasses or sunglasses, mobile devices, devices for virtual reality (VR) or augmented reality (AR). ), Or a wearable device such as a window of a vehicle or a device applied outdoors.

In the case of a device that controls the transmittance by applying a liquid crystal compound, polarization of a certain level or higher is basically generated. In these devices, crosstalk is caused by reflection of light reflected by road surfaces, structures, buildings, etc., depending on the use environment. ), A rainbow phenomenon, or a mirroring phenomenon.

European Patent Publication No. 0022311

This application relates to a device with variable transmission. An object of the present application is to provide a variable transmittance device that can be applied to various uses without causing problems such as a crosstalk phenomenon, a rainbow phenomenon, or a mirroring phenomenon.

The angle defined in this specification should be understood in consideration of errors such as manufacturing error or variation. For example, in the present specification, the terms vertical, parallel, orthogonal or horizontal, etc., mean substantially vertical, parallel, orthogonal or horizontal in a range that does not impair the desired effect, for example, in each case, about It can include errors within ± 10 degrees, errors within approximately ± 5 degrees, errors within approximately ± 3 degrees, errors within approximately ± 2 degrees, errors within approximately ± 1 degrees, or errors within approximately ± 0.5 degrees. have.

Among the properties mentioned in the present specification, the properties are properties measured at room temperature, unless otherwise specified, when the measurement temperature affects the properties.

As used herein, the term room temperature is a temperature in a state that is not particularly warmed or reduced, and any temperature within a range of about 10 ° C to 30 ° C, for example, about 15 ° C or more, 18 ° C or more, 20 ° C or more, or about 23 It may mean a temperature of about 27 ° C or lower while being more than ℃. In addition, unless otherwise specified, the temperature unit mentioned in this specification is ℃.

The phase difference, refractive index, refractive index anisotropy, etc. referred to in this specification are physical quantities for light having a wavelength of about 550 nm unless otherwise specified.

Unless otherwise specified, an angle formed by any two directions referred to herein may be an acute angle from an acute angle to an obtuse angle formed by the two directions, or a small angle among angles measured in clockwise and counterclockwise directions. . Therefore, unless otherwise specified, the angle mentioned in this specification is a positive number. However, in some cases, in order to display a measurement direction between angles measured in a clockwise or counterclockwise direction, the angle measured in the clockwise direction may be displayed as a positive number, and the angle measured in the counterclockwise direction may be expressed as a negative number.

In the present application, by applying a specific retardation film in a specific arrangement, it is possible to provide a variable transmittance device that does not cause problems such as the crosstalk phenomenon, the rainbow phenomenon, or the mirroring phenomenon.

In the present application, the term variable transmission device may mean a device capable of switching between at least two or more different states of light. In the above, the state of the other light may mean a state in which transmittance is different.

As an example of a state in which the variable transmittance device can be implemented, a state of transmission and blocking mode may be exemplified. In one example, the variable transmission device of the present application may be a device capable of switching between at least the transmission and blocking mode states.

The transmittance of the variable transmittance device in the transmission mode state is at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65 % Or more, 70% or more, 75% or more, or 80% or more. In addition, in the blocking mode, the transmittance of the variable transmittance device is 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15 % Or less, 10% or less, or 5% or less. In the transmissive mode, the higher the transmittance is, the lower the transmittance in the blocking mode is advantageous. Therefore, the upper limit of the transmittance in the transmissive mode state and the lower limit of the transmittance in the blocking mode state are not particularly limited. The upper limit of the transmittance of about 100%, the lower limit of the transmittance in the blocking mode state may be about 0%.

In one example, the difference between the transmittance in the transmittance mode state and the transmittance in the cutoff mode state (transmission mode-cutoff mode) in a transmittance variable device capable of switching between the transmittance mode state and the cutoff mode state is 15% or more. , 20% or more, 25% or more, 30% or more, 35% or more, or 40% or more, or 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less , 55% or less, 50% or less, or 45% or less.

In addition, in one example, the ratio (Tmax / Tmin) of the maximum transmittance (Tmax) in the transmission mode state and the minimum transmittance (Tmin) in the blocking mode state may be in a range of about 1.5 to 10. In other examples, the ratio is about 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, 4.5 or more, 5 or more, 6 or more, or 6.5 or more, or about 9.5 or less, about 9 or less, about 8.5 or less, or about 8 or less , About 7.5 or less, about 7 or less, about 6.5 or less, about 6 or less, about 5.5 or less, about 5 or less, about 4.5 or less, about 4 or less, about 3.5 or less, about 3 or less, about 2.5 or less or about 2 or less .

The transmittance may be, for example, straight light transmittance. The linear light transmittance is a percentage of the ratio of light transmitted in the same direction as the incident direction to light incident on the device. For example, if the device is in the form of a film or sheet, the percentage of light transmitted through the device in a direction parallel to the normal direction among light incident in a direction parallel to the normal direction of the film or sheet surface is defined as the transmittance. You can.

The transmittance may be a transmittance or reflectance of a visible light region, for example, a wavelength within a range of about 400 to 700 nm or about 380 to 780 nm, or a transmittance or reflectance of the entire visible light region, or the entire visible light region, respectively. It may be the maximum or minimum transmittance or reflectance among the transmittance or reflectance for, or may be an average value of transmittance in the visible light region or an average value of reflectance. Further, in another example, the transmittance may be transmittance for light having a wavelength of about 550 nm.

The variable transmittance device of the present application may be designed to switch between at least two or more states of one state and the other state selected in the transmission and blocking mode states. If necessary, other third states or higher states may be implemented in addition to the above states, for example, states of intermediate transmittance of the transmission mode and the blocking mode state.

Switching of the variable transmittance device as described above may be adjusted according to whether an external signal is applied, for example, a voltage signal is applied. For example, in the absence of the application of an external signal such as a voltage, the variable transmittance device may maintain one of the states described above, and then switch to another state when a voltage is applied. By changing the strength, frequency, and / or shape of the applied voltage, the mode state can also be changed, or the third other mode state can be implemented.

The variable transmittance device of the present application may include at least a variable transmittance layer for such switching. The variable transmittance layer may be a layer that generates a polarization component in one example. An example of such a variable transmittance layer is an active liquid crystal layer.

In the present application, the term active liquid crystal layer is a layer containing at least a liquid crystal compound, and may mean a liquid crystal layer capable of controlling the alignment state of the liquid crystal compound through popularity of external signals. However, the application of the active liquid crystal layer is one example of the present application, and if necessary, other known transmittance variable layers, for example, an electrochromic material layer, a photochromic material layer, an electrophoretic material layer, or a dispersed particle alignment layer, etc. This can also be used.

The active liquid crystal layer is a layer containing a liquid crystal compound. In this specification, the term active liquid crystal layer includes a layer including a liquid crystal compound capable of controlling its orientation through application of an external signal, etc., and includes, for example, a liquid crystal compound (liquid crystal host) as described below. The so-called guest host layer containing a dichroic dye is also a type of liquid crystal layer defined in this specification. As the liquid crystal compound, all kinds of liquid crystal compounds can be used as long as the orientation direction can be changed by the application of an external signal. For example, as a liquid crystal compound, a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound may be used. In addition, the liquid crystal compound may be, for example, a compound having no polymerizable group or a crosslinkable group so that the orientation direction can be changed by application of an external signal.

The liquid crystal layer may include a liquid crystal compound having a positive or negative dielectric anisotropy, or the liquid crystal layer may exhibit the aforementioned dielectric anisotropy. The absolute value of the dielectric anisotropy can be appropriately selected in consideration of the purpose of the present application. The term "dielectric constant anisotropy (△ ε)" may mean the difference (ε //-ε⊥) between the horizontal dielectric constant (ε //) and the vertical dielectric constant (ε⊥). In this specification, the term horizontal dielectric constant (ε //) means a dielectric constant value measured along the direction of the electric field in a state in which a voltage is applied so that the direction of the electric field by the direction of the liquid crystal molecule and the applied voltage are substantially horizontal, The vertical permittivity (ε⊥) means a dielectric constant value measured along the direction of the electric field in a state in which a voltage is applied such that the direction of the liquid crystal molecules and the direction of the electric field by the applied voltage are substantially perpendicular.

The liquid crystal layer may include a liquid crystal compound having a refractive index anisotropy (nΔ) in a range of about 0.03 to 0.2, or the liquid crystal layer may exhibit the aforementioned refractive index anisotropy. The refractive index anisotropy (nΔ) referred to in the present application is the difference between the abnormal refractive index (ne, extraordinary refractive index) and the normal refractive index (no-ne), which can be confirmed using an Abbe refractometer. The specific method follows the method disclosed in the following examples.

The driving mode of the liquid crystal layer is, for example, DS (Dynamic Scattering) mode, ECB (Electrically Controllable Birefringence) mode, IPS (In-Plane Switching) mode, FFS (Fringe-Field Wwitching) mode, OCB (Optially Compensated Bend) Mode, Vertical Alignment (VA) mode, Multi-domain Vertical Alignment (MVA) mode, Patterned Vertical Alignment (PVA) mode, Hybrid Aligned Nematic (HAN) mode, Twisted Nematic (TN) mode, Super Twisted Nematic (STN) mode, etc. Can be illustrated.

The active liquid crystal layer, which is a variable transmittance layer, may further include a dichroic dye together with the liquid crystal compound in terms of controlling light transmittance variable characteristics. In this case, the active liquid crystal layer may be referred to as a guest host liquid crystal cell, which will be described later. In the present specification, the term "dye" may mean a material capable of intensively absorbing and / or modifying light in at least a part or the entire range of a visible light region, for example, within a wavelength range of 400 nm to 700 nm, The term "dichroic dye" may mean a material capable of anisotropic absorption of light in at least a portion or the entire range of the visible light region. Such dyes are known as, for example, azo dyes or anthraquinone dyes, but are not limited thereto.

In one example, the variable transmittance layer is a liquid crystal layer including a liquid crystal and a dichroic dye, and may be a so-called guest host liquid crystal cell. The term "GHLC layer" may mean a functional layer in which dichroic dyes are arranged together according to the arrangement of liquid crystals, and exhibit anisotropic light absorption characteristics with respect to the alignment direction of the dichroic dye and the vertical direction of the alignment direction. have. For example, a dichroic dye is a material whose absorption rate of light varies depending on the polarization direction. If the absorption rate of light polarized in the long axis direction is large, it is called a p-type dye, and when the absorption rate of light polarized in the short axis direction is large, it is called an n-type dye. It can be called. In one example, when a p-type dye is used, polarization vibrating in the long axis direction of the dye is absorbed, and polarization vibrating in the short axis direction of the dye is less absorbed and can be transmitted. Hereinafter, unless otherwise specified, it is assumed that the dichroic dye is a p-type dye.

The ratio of the dichroic dye included in the guest host liquid crystal layer is not particularly limited, and may be set to an appropriate range in consideration of a desired transmittance. In general, considering the miscibility of the dichroic dye and the liquid crystal compound, the dichroic dye may be included in the liquid crystal layer at a ratio of about 0.1% to 4% by weight.

The light modulating film layer including the guest host liquid crystal layer as a variable transmittance layer may function as an active polarizer. In this specification, the term "active polarizer (Active Polarizer)" may mean a functional element that can adjust the anisotropic light absorption according to the application of an external signal. Such an active polarizer may be distinguished from a passive polarizer, which will be described later, having constant light absorption or light reflection characteristics regardless of external signal application. The guest host liquid crystal layer may adjust the arrangement of the liquid crystal and the dichroic dye to control the anisotropic light absorption for polarization in the direction parallel to the alignment direction of the dichroic dye and polarization in the vertical direction. Since the arrangement of the liquid crystal and the dichroic dye can be controlled by the application of an external signal such as a magnetic field or an electric field, the guest host liquid crystal layer can control anisotropic light absorption according to the application of an external signal.

In one example, the active liquid crystal layer may be configured to be able to switch between at least one of a vertical alignment mode, a horizontal alignment mode, and an inclination alignment mode. The meanings of the vertical, horizontal and inclined orientation modes are according to known content.

Thus, for example, the term horizontal alignment state may mean a state in which the direction of the active liquid crystal layer, which is a variable transmittance layer, or the direction of the liquid crystal compound in the liquid crystal layer is substantially parallel to the variable layer (liquid crystal layer). . In this case, the angle between the director and the variable layer on the side of the variable layer (liquid crystal layer) may be in a range of approximately 0 degrees to 10 degrees or approximately 0 degrees to 5 degrees, or may be approximately 0 degrees.

Further, for example, the term vertical alignment state is a state in which the direction of the active liquid crystal layer, which is a variable transmittance layer, or the direction of the liquid crystal compound in the liquid crystal layer is arranged substantially perpendicular to the plane of the variable layer (liquid crystal layer), For example, the angle between the director and the variable layer (liquid crystal layer) on the side of the variable layer (liquid crystal layer) is, for example, in the range of about 80 degrees to 100 degrees or 85 degrees to 95 degrees, Approximately 90 degrees can be achieved.

Further, for example, the term inclined alignment state is an alignment state of the intermediate state of the vertical alignment state and the horizontal alignment state, and the direction of the variable layer (liquid crystal layer) on the side of the variable layer (liquid crystal layer) or the It may mean a case in which the angle of the liquid crystal compound in the liquid crystal layer with the variable layer (liquid crystal layer) is more than 0 degrees and less than 90 degrees, or is within a range of approximately 10 degrees to 80 degrees.

In this specification, the direction of the liquid crystal molecule or the liquid crystal compound may mean an optical axis or a slow axis of the active liquid crystal layer. The director of the liquid crystal molecules may mean a long axis direction when the liquid crystal molecules are rod-shaped, and may mean an axis in a normal direction of the plane of the disc when the liquid crystal molecules are discotic. When a plurality of liquid crystal compounds having different orientations exist in the active liquid crystal layer, the orientation is a vector sum.

In one example, the active liquid crystal layer that is the variable transmittance layer may be designed to implement at least a twist alignment mode. The term twist alignment mode may refer to a spiral structure in which liquid crystal compounds in a liquid crystal layer are aligned while being twisted along a virtual spiral axis. The twist alignment mode may be implemented in the above-described vertical, horizontal or inclined alignment mode, that is, the vertical twist alignment mode is a state in which individual liquid crystal compounds are layered while twisting along a spiral axis in a vertically aligned state, and horizontally. Twisted alignment mode is a state in which individual liquid crystal compounds are twisted along a spiral axis in a horizontally aligned state, and inclined twisted alignment mode is a state in which individual liquid crystal compounds are twisted along a spiral axis in a tilted state. .

In the twist alignment mode, the ratio (d / p) of the thickness (d) and the pitch (p) of the liquid crystal layer may be 1 or less. If the ratio (d / p) exceeds 1, there may be a problem in that a finger domain or the like may be generated, and thus it can be adjusted to the above range. The lower limit of the ratio (d / p) is not particularly limited, but may be about 0.6 or more or about 0.6 or more. In the above, the thickness (d) of the liquid crystal layer may mean the same as the cell gap of the liquid crystal cell.

The pitch (p) of the liquid crystal layer in the twist alignment mode can be measured by a measurement method using a Wedge cell, and specifically, Simple method for accurate measurements of the cholesteric pitch using a stripe-wedge Grandjean-Cano cell (Liquid Crystals, Vol. 35, No. 7, July 2008, 789-791).

The liquid crystal layer may further include a so-called chiral agent so that the liquid crystal layer can implement a twist mode. That is, the active liquid crystal layer may include at least a liquid crystal compound and a chiral agent, or at least a liquid crystal compound and a dichroic dye and a chiral agent. The chiral agent or chiral dopant that may be included in the liquid crystal layer is not particularly limited as long as it can induce desired rotation without impairing liquid crystal properties, for example, nematic regularity. Can be used. The chiral agent for inducing rotation in the liquid crystal molecule needs to contain at least chirality in the molecular structure. As a chiral agent, for example, a compound having one or two or more asymmetric carbons, a compound having an asymmetric point on a heteroatom such as a chiral amine or a chiral sulfoxide, or a cumulene ) Or a compound having an optically active site (axially asymmetric, optically active site) having an accumulator such as binaphthol. Chiral agents can be, for example, low molecular weight compounds having a molecular weight of 1,500 or less. As a chiral agent, a commercially available chiral nematic liquid crystal, for example, a chiral dopant liquid crystal S-811 commercially available from Merck or LC756 from BASF can be used.

The application rate of the chiral agent is not particularly limited as it is selected so as to achieve the desired ratio (d / p). In general, the content (% by weight) of the chiral agent is calculated by the formula of 100 / (HTP (Helixcal Twisting power) × pitch (nm), and an appropriate ratio can be selected in consideration of the desired pitch by referring to this method. .

The thickness of the variable transmittance layer may be appropriately selected in consideration of the purpose of each application. In one example, the thickness of the variable transmittance layer is about 0.01 μm or more, 0.1 μm or more, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, and 8 μm. Or more, 9 μm or more, or 10 μm or more. By controlling the thickness in this way, a device having a large difference in transmittance according to the mode state can be implemented. The thicker the thickness is, the higher the transmittance and / or the reflectivity can be realized, so it is not particularly limited, but may be generally about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

The device of the present application further includes a retardation film disposed on at least one surface of the above-mentioned variable transmittance layer. 1 is a schematic diagram of a device according to an example of the present application, and shows the retardation film 100 and the variable layer 200 arranged in an orderly manner.

In the present application, a device having no so-called rainbow phenomenon, mirroring phenomenon, and crosstalk phenomenon can be provided by arranging a film having an optically large anisotropy as a specific position as the retardation film. Incidentally, by applying an anisotropic film in terms of mechanical properties as the retardation film, a device having excellent mechanical properties can also be constructed.

In the present specification, the retardation film that is anisotropic in terms of optical and mechanical properties may be referred to as an asymmetric substrate or an asymmetric retardation film. In the above, the retardation film is optically anisotropic in the case of having an in-plane retardation described later, and in terms of mechanical properties, the retardation film is in the case of having the properties described later.

Hereinafter, the physical properties of the retardation film referred to in this specification may be physical properties of the retardation film itself or physical properties in a state where an electrode layer is formed on one surface of the retardation film. In this case, the electrode layer may be an electrode layer formed while the retardation film is included in the optical device.

The physical properties of each retardation film referred to in this specification are measured according to the method described in the Examples section of this specification.

In one example, the in-plane retardation of the retardation film may be about 4,000 nm or more. The in-plane retardation is a value for light having a wavelength of 550 nm.

In this specification, the in-plane phase difference (Rin) may mean a value calculated by Equation A below.

[Formula A]

Rin = d × (nx-ny)

In Equation A, Rin is the in-plane retardation, d is the thickness of the retardation film, nx is the refractive index in the slow axis direction of the retardation film, and ny is the refractive index in the fast axis direction, and is the refractive index in the in-plane direction orthogonal to the slow axis direction. .

The in-plane retardation of the retardation film is 4,500 nm or more, 5,000 nm or more, 6,000 nm or more, 7,000 nm or more, 8,000 nm or more, 9,000 m or more, 10,000 m or more, 11,000 m or more, 12,000 m or more, 13,000 m or more, 14,000, respectively. It may be more than m or more than 15,000 m. In addition, the in-plane retardation of each of the retardation films may be about 50,000 nm or less, about 40,000 nm or less, about 30,000 nm or less, 20,000 nm or less, 18,000 nm or less, 16,000 nm or less, 15,000 nm or less, or 12,000 nm or less.

As the film having such a large phase difference, a film known as a so-called high-strength poly (ethylene terephthalate) (PET) film or a super retardation film (SRF) is typically known. Therefore, in the present application, the retardation film may be, for example, a polyester film.

Films having an extremely high retardation as described above are well known in the industry, and such films exhibit great asymmetry as well as optically large anisotropy as well as mechanical properties due to high stretching in the manufacturing process. State known to the industry A typical example of the retardation film is a polyester film such as a PET (poly (ethylene terephthalate)) film, for example, a brand of SRF (Super Retardation Film) series supplied by Toyobo. .

In one example, the retardation film may have a ratio (E1 / E2) of elongation (E1) in an arbitrary first direction in a plane and elongation (E2) in a second direction perpendicular to the first direction (3). . The ratio (E1 / E2) may be about 3.5 or more, 4 or more, 4.5 or more, 5 or more, 5.5 or more, 6 or more, or 6.5 or more in other examples. The ratio (E1 / E2) may be about 20 or less, 18 or less, 16 or less, 14 or less, 12 or less, 10 or less, 8 or less, or 7.5 or less in other examples.

As used herein, the terms first, second, and third directions of the retardation film are any directions in the plane of the film. For example, when the retardation film is a stretched retardation film, the in-plane direction may be an in-plane direction formed by a machine direction (MD) and a transverse direction (TD) direction of the retardation film. In one example, the first direction described in this specification may be any one of a slow axis and a slow axis direction of the retardation film, and the second direction may be another direction of a slow axis and a slow axis direction. In another example, when the retardation film is a stretched retardation film, the first direction is any one of a MD (Machine Direction) and a TD (transverse direction) direction, and the second direction is a MD (Machine Direction) and a TD (transverse direction) ) May be the other of the directions.

In one example, the first direction of the retardation film referred to herein may be the TD direction or the slow axis direction.

The elongation in the first direction (for example, the above-mentioned slow axis direction or TD direction) of the retardation film may be 15% or more or 20% or more. In another example, the elongation may be about 25% or more, 30% or more, 35% or more, or 40% or more, or about 60% or less, 55% or less, 50% or less, or 45% or less.

In one example, the retardation film has an elongation (E1) in the first direction and an elongation (E3) in the third direction forming an angle or about 45 degrees in the range of 40 degrees to 50 degrees with the first and second directions, respectively. ), The ratio (E3 / E2) of the elongation (E3) in the third direction and the elongation (E2) in the second direction may be 5 or more.

The ratio (E3 / E2) may be 5.5 or more, 6 or more, 6.5 or more, 7 or more, 7.5 or more, 8 or more, or 8.5 or more in other examples, about 20 or less, 18 or less, 16 or less, 14 or less, 12 or less, or It may be 10 or less.

The elongation in the third direction of the retardation film may be 30% or more. In another example, the elongation may be about 35% or more, 40% or more, 45% or more, 50% or more, or 55% or more, or about 80% or less, 75% or less, 70% or less, or 65% or less.

In the retardation film, a ratio (CTE2 / CTE1) of a coefficient of thermal expansion (CTE2) in the second direction and a coefficient of thermal expansion (CTE1) in the first direction may be 1.5 or more. The coefficients of thermal expansion (CTE1, CTE2) are values identified within a temperature range of 40 ° C to 80 ° C, respectively. The ratio (CTE2 / CTE1) may be about 2 or more, about 2.5 or more, 3 or more, or 3.5 or more, or 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less in other examples.

The coefficient of thermal expansion (CTE2) in the second direction may be in the range of 5 to 150 ppm / ° C. The coefficient of thermal expansion is about 10 ppm / ℃ or higher, 15 ppm / ℃ or higher, 20 ppm / ℃ or higher, 25 ppm / ℃ or higher, 30 ppm / ℃ or higher, 35 ppm / ℃ or higher, 40 ppm / ℃ or higher, 45 ppm / ℃ or higher, 50 ppm / ℃ or higher, about 55 ppm / ℃ or higher, 60 ppm / ℃ or higher, 65 ppm / ℃ or higher, 70 ppm / ℃ or higher, 75 ppm / ℃ or higher, or 80 ppm / ℃ or higher, or 140 ppm / ℃ or less, 130 ppm / ° C or less, 120 ppm / ° C or less, 100 ppm / ° C or less, 95 ppm / ° C or less, 90 ppm / ° C or less, 85 ppm / ° C or less, 80 ppm / ° C or less, 40 ppm / ° C or less , 30 ppm / ℃ or less or 25 ppm / ℃ or less.

In the retardation film, a ratio (YM1 / YM2) of the elastic modulus YM2 in the second direction and the elastic modulus YM1 in the first direction may be 1.5 or more. The ratio (YM1 / YM2) may be about 2 or more, or 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2.5 or less in other examples.

The elastic modulus YM1 in the first direction may be in a range of about 2 to 10 GPa. The elastic modulus (YM1) is, in another example, about 2.5 GPa or more, 3 GPa or more, 3.5 GPa or more, 4 GPa or more, 4.5 GPa or more, 5 GPa or more, or 5.5 GPa or more, or about 9.5 GPa or less, 9 GPa or less, 8.5 GPa or less, 8 GPa Hereinafter, it may be 7.5 GPa or less, 7 GPa or less, 6.5 GPa or less, or 6 GPa or less.

The modulus of elasticity may mean a so-called Young's modulus.

In the retardation film, a ratio (MS1 / MS2) of a maximum stress (MS2) in the second direction and a maximum stress (MS1) in the first direction may be 1.5 or more. The ratio (MS1 / MS2) may be about 2 or more, or 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2.5 or less in other examples.

The maximum stress (MS1) in the first direction (for example, the above-described slow axis direction or TD direction) may be in a range of about 80 to 300 MPa. The maximum stress (MS1), in another example, about 90 MPa or more, about 100 MPa or more, about 110 MPa or more, about 120 MPa or more, about 130 MPa or more, about 140 MPa or more, about 150 MPa or more, about 155 MPa or more, 160 MPa or more, 165 MPa or more, 170 MPa or more, 175 MPa or more, or 180 MPa or more, or about 300 MPa or less, about 290 MPa or less, about 280 MPa or less, about 270 MPa or less, about 260 MPa or less, about 250 MPa or less, about 245 MPa or less, It may be 240 MPa or less, 235 MPa or less, 230 MPa or less, 225 MPa or less, 220 MPa or less, 215 MPa or less, 210 MPa or less, 205 MPa or less, 200 MPa or less, 195 MPa or less, or 190 MPa or less.

A representative example of a polymer film having such large optical and mechanical asymmetry as described above is a stretched PET (polyethyleneterephtalate) film known as a so-called high-stretched polyester film, which is readily available in the industry.

Normally, a stretched PET film is a biaxially stretched film produced by forming a PET resin by melt / extrusion, stretching at least one uniaxially oriented film prepared by stretching, or vertically and transversely stretching after forming.

PET-based resin usually means a resin in which 80 mol% or more of the repeating unit is ethylene terephthalate, and may include other dicarboxylic acid components and diol components. Although it does not specifically limit as another dicarboxylic acid component, For example, isophthalic acid, p-beta-oxyethoxybenzoic acid, 4,4'- dicarboxydiphenyl, 4,4'- dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid and / or 1,4-dicarboxycyclohexane and the like.

The other diol component is not particularly limited, but propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol and / or polytetramethylene glycol, etc. Can be mentioned.

 The dicarboxylic acid component or the diol component may be used in combination of two or more kinds as necessary. Moreover, oxycarboxylic acids, such as p-oxybenzoic acid, can also be used together. Further, as another copolymerization component, a dicarboxylic acid component containing a small amount of an amide bond, a urethane bond, an ether bond and a carbonate bond, or a diol component may be used.

As a method for producing the PET-based resin, a method of directly polycondensing terephthalic acid, ethylene glycol and / or other dicarboxylic acids or other diols as necessary, dialkyl esters of terephthalic acid and ethylene glycol and / or other dicars as necessary A method for polycondensation after transesterification of a dialkyl ester or other diol of a carboxylic acid, and for polycondensation of terephthalic acid and / or ethylene glycol ester of another dicarboxylic acid and / or other diol ester as necessary Method or the like is employed.

For each polymerization reaction, a polymerization catalyst containing an antimony-based, titanium-based, germanium-based or aluminum-based compound, or a polymerization catalyst containing the complex compound can be used.

The polymerization reaction conditions can be appropriately selected depending on the monomers, catalysts, reaction devices and the desired resin properties, and are not particularly limited, for example, the reaction temperature is usually about 150 ° C to about 300 ° C, about 200 ° C To about 300 ° C or about 260 ° C to about 300 ° C. In addition, the reaction pressure is usually atmospheric pressure to about 2.7 Pa, and may be on the reduced pressure side in the second half of the reaction.

The polymerization reaction proceeds by volatilizing a leaving reaction product such as a diol, an alkyl compound, or water.

The polymerization apparatus may be one in which the reaction tank is completed, or may be one in which a plurality of reaction tanks are connected. In this case, depending on the degree of polymerization, the reactants are polymerized while being transferred between the reactors. In addition, a horizontal reaction device is provided at the end of polymerization, and a method of volatilization while heating / kneading can also be adopted.

After the polymerization is finished, the resin is released from the reaction tank or the horizontal reaction device in a molten state, and then cooled or crushed in a cooling drum or cooling belt, or in the form of pellets after being introduced into an extruder and extruded into a string. Is obtained. Further, if necessary, solid phase polymerization may be performed to improve molecular weight or reduce low molecular weight components. Examples of the low molecular weight component that can be included in the PET-based resin include a cyclic trimer component, but the content of the cyclic trimer component in the resin is usually adjusted to 5000 ppm or less or 3000 ppm or less.

The molecular weight of the PET-based resin is usually 0.45 to 1.0 dL / g, 0.50 to 0.50, when the resin is dissolved in a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) and expressed at an extreme viscosity measured at 30 ° C. 10 dL / g or 0.52 to 0.80 dL / g.

Further, the PET-based resin may contain additives as necessary. Examples of the additives include lubricants, anti-blocking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents and impact resistance improvers. It is preferable that the addition amount is within a range that does not adversely affect the optical properties.

PET-based resins are usually used in the form of pellets assembled by an extruder for the mixing of these additives and for the film forming described later. The size and shape of the pellets are not particularly limited, but are usually columnar, spherical, or flat spherical with a height and diameter of 5 mm or less. The PET-based resin thus obtained can be formed into a film and stretched to obtain a transparent and homogeneous PET film with high mechanical strength. Although it does not specifically limit as a manufacturing method, the method described next is employ | adopted, for example.

The pellet composed of the dried PET resin is supplied to a melt extrusion apparatus, and heated to a melting point or higher to melt. Next, the molten resin is extruded from the die and rapidly cooled and solidified to a temperature below the glass transition temperature on a rotary cooling drum, thereby obtaining an unstretched film in a substantially amorphous state. The melting temperature is determined depending on the melting point or extruder of the PET resin used, and is not particularly limited, but is usually 250 ° C to 350 ° C. Further, in order to improve the flatness of the film, it is preferable to increase the adhesion between the film and the rotary cooling drum, and an electrostatically applied adhesion method or a liquid coating adhesion method is preferably employed. With the electrostatic application adhesion method, a linear electrode is usually provided in a direction orthogonal to the flow of the film on the upper surface side of the film, and a DC voltage of about 5 to 10 kV is applied to the electrode to provide static charge to the film and to rotate cooling It is a method to improve the adhesion between the drum and the film. In addition, the liquid coating adhesion method is a method of improving the adhesion between the rotating cooling drum and the film by uniformly applying the liquid to all or part of the surface of the rotating cooling drum (for example, only the portion in contact with both ends of the film). Both can also be used together if necessary. The PET-based resin used may be mixed with two or more kinds of resins, resins having different structures or compositions, as necessary. For example, a pellet containing a granular filler as an antiblocking agent, an ultraviolet absorber or an antistatic agent, and a mixture of pellets without mixing may be used.

In addition, the number of layers of the film to be extruded may be two or more layers if necessary. For example, a pellet composed of a granule filler as an anti-blocking agent and a non-blended pellet are prepared, and supplied from the other extruder to the same die to form a film composed of two or three layers of "filler blend / unblended / filler blend" And extrusion.

The unstretched film is usually stretched longitudinally in the extrusion direction, usually at a temperature above the glass transition temperature. The stretching temperature is usually 70 ° C to 150 ° C, 80 to 130 ° C or 90 to 120 ° C. In addition, the draw ratio is usually 1.1 to 6 times or 2 to 5.5 times. Stretching may be completed once or divided into multiple times as necessary.

The longitudinal stretched film obtained in this way can be heat-processed after this. Subsequently, a relaxation treatment may be performed as necessary. The heat treatment temperature is usually 150 ° C to 250 ° C, 180 to 245 ° C or 200 to 230 ° C. Further, the heat treatment time is usually 1 to 600 seconds or 1 to 300 seconds or 1 to 60 seconds.

The temperature of the relaxation treatment is usually 90 to 200 ° C or 120 to 180 ° C. In addition, the amount of relaxation is usually 0.1 to 20% or 2 to 5%. As for the temperature and the amount of relaxation of the relaxation treatment, the relaxation amount and the temperature at the time of the relaxation treatment can be set so that the heat shrinkage rate at 150 ° C of the PET film after the relaxation treatment is 2% or less.

In the case of obtaining a uniaxially stretched and biaxially stretched film, transverse stretching is usually performed by a tenter after a longitudinal stretching treatment or after heat treatment or relaxation treatment as necessary. The stretching temperature is usually 70 ° C to 150 ° C, 80 ° C to 130 ° C, or 90 ° C to 120 ° C. In addition, the draw ratio is usually 1.1 to 6 times or 2 to 5.5 times. Thereafter, heat treatment and relaxation treatment can be performed as necessary. The heat treatment temperature is usually 150 ° C to 250 ° C or 180 ° C to 245 ° C or 200 to 230 ° C. The heat treatment time is usually 1 to 600 seconds, 1 to 300 seconds, or 1 to 60 seconds.

The temperature of the relaxation treatment is usually 100 to 230 ° C, 110 to 210 ° C, or 120 to 180 ° C. In addition, the relaxation amount is usually 01 to 20%, 1 to 10%, or 2 to 5%. As for the temperature and the amount of relaxation of the relaxation treatment, the relaxation amount and the temperature at the time of the relaxation treatment can be set so that the heat shrinkage rate at 150 ° C of the PET film after the relaxation treatment is 2% or less.

In the uniaxial stretching and biaxial stretching treatment, after transverse stretching, in order to alleviate the deformation of the oriented main axis as represented by Boeing, heat treatment or stretching treatment may be performed again. The maximum value of deformation with respect to the stretching direction of the orientation main axis by boeing is usually within 45 degrees, within 30 degrees, or within 15 degrees. In addition, the extending | stretching direction here means the extending | stretching large direction in longitudinal stretch or transverse stretch.

In the biaxial stretching of the PET film, the case of the transverse stretching magnification is usually slightly larger than the longitudinal stretching magnification, and in this case, the stretching direction refers to a direction perpendicular to the long direction of the film. In addition, in uniaxial stretching, it is usually stretched in the horizontal direction as described above, and in this case, the stretching direction means the vertical direction with respect to the same long direction.

In addition, an orientation main axis means the molecular orientation direction at arbitrary points on a stretched PET film. In addition, the deformation | transformation with respect to the extending direction of an orientation main axis means the angle difference between an orientation main axis and an extending direction. In addition, the maximum value means the maximum value of the value in the vertical direction with respect to a long direction.

The orientation direction of the orientation main axis is known, and can be measured, for example, using a retardation film and optical material inspection device RETS (manufactured by Otsuka Denshi Co., Ltd.) or molecular orientation system MOA (manufactured by Oji Keisukki Co., Ltd.). You can.

To the stretched PET film, functional layers other than the anti-glare layer or the like can be laminated on one side or both sides, as long as the effects of the present application are not impaired. Examples of the functional layer to be stacked include a conductive layer, a hard coating layer, a smoothing layer, an easily lubricating layer, an anti-blocking layer, and an easily adhesive layer.

The above-described manufacturing method is one exemplary method for obtaining the retardation film of the present application, and the retardation film applicable in the present application may have any commercially available product if it has the above-described physical properties.

In the device of the present application, the retardation film is included in the device such that the slow axis of the film has a specific positional relationship.

In one example, the device may include a liquid crystal alignment layer, which will be described later, between the retardation film and the variable transmittance layer. In this case, an angle between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer is 0 degrees. It may be in the range of 70 to 70 degrees. 2 is a schematic diagram of the case where the retardation film 100, the liquid crystal alignment layer 300, and the variable transmittance layer 200 are sequentially arranged in the above example. The angle is a small angle among the angles formed by the orientation direction and the slow axis, and may be in a range of 0 degrees to 360 degrees in one example. In other examples, the angle is greater than 0 degrees, 2 degrees or more, 4 degrees or more, 6 degrees or more, 8 degrees or more, 10 degrees or more, 12 degrees or more, 14 degrees or more, 16 degrees or more, 18 degrees or more, 20 degrees or more, Above 22 degrees, above 24 degrees, above 26 degrees, above 28 degrees, above 30 degrees, above 32 degrees, above 34 degrees, above 36 degrees, above 38 degrees, above 40 degrees, above 42 degrees, above 44 degrees, above 46 degrees Above, above 48 degrees or above 50 degrees, below 360 degrees, below 350 degrees, below 340 degrees, below 330 degrees, below 320 degrees, below 310 degrees, below 300 degrees, below 290 degrees, below 280 degrees, below 270 degrees , 260 degrees or less, 250 degrees or less, 240 degrees or less, 230 degrees or less, 220 degrees or less, 210 degrees or less, 200 degrees or less, 190 degrees or less, 180 degrees or less, 170 degrees or less, 160 degrees or less, 150 degrees or less, 140 It may be less than or equal to, less than or equal to 130 degrees, less than or equal to 120 degrees, less than or equal to 110 degrees, less than or equal to 100 degrees, less than or equal to 90 degrees, less than or equal to 80 degrees, less than or equal to 70 degrees, or less than or equal to 60 degrees. The liquid crystal alignment layer may be used to determine initial alignment of liquid crystals in the liquid crystal layer when the variable transmittance layer is an active liquid crystal layer. The type of the liquid crystal alignment film applied at this time is not particularly limited, and may be, for example, a known rubbing alignment film or a photo-alignment film. As described later, there are cases where alignment films are present on both sides of the active liquid crystal layer. In this case, the alignment film having a slow axis of the retardation film and an alignment direction of the angle is an alignment direction of the alignment film positioned close to the retardation film. The alignment direction may be a rubbing direction in the case of a rubbing alignment film, and a direction of polarized light irradiated in the case of a photo-alignment film, which can be confirmed by a detection method using a linear polarizer. For example, when a liquid crystal layer (transmissivity variable layer) is a twist alignment mode such as a STN (Super Twisted Nematic) mode, a linear polarizer is disposed on one surface, and the transmittance is measured while changing the absorption axis of the polarizer. Alternatively, when the transmission axis and the alignment direction of the liquid crystal alignment layer coincide, the transmittance tends to be low. The alignment direction may be confirmed through simulation reflecting anisotropy of the refractive index of the applied liquid crystal compound. The method of confirming the alignment direction according to the mode of the liquid crystal layer (variable transmittance layer) is known, and in this application, the angle formed by the alignment direction and the slow axis of the liquid crystal alignment layer can be confirmed by such a known method.

In another example, in the case where the variable transmittance is an active liquid crystal layer capable of implementing the above-described twist alignment mode, the twist alignment of the angle formed by the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer in the alignment direction of the liquid crystal alignment layer When measured along the twisting direction of the mode, the retardation film may be disposed to be within a range of 0 degrees to 360 degrees. In other examples, the angle is greater than 0 degrees, 2 degrees or more, 4 degrees or more, 6 degrees or more, 8 degrees or more, 10 degrees or more, 12 degrees or more, 14 degrees or more, 16 degrees or more, 18 degrees or more, 20 degrees or more, Above 22 degrees, above 24 degrees, above 26 degrees, above 28 degrees, above 30 degrees, above 32 degrees, above 34 degrees, above 36 degrees, above 38 degrees, above 40 degrees, above 42 degrees, above 44 degrees, above 46 degrees Above, above 48 degrees or above 50 degrees, below 360 degrees, below 350 degrees, below 340 degrees, below 330 degrees, below 320 degrees, below 310 degrees, below 300 degrees, below 290 degrees, below 280 degrees, below 270 degrees , 260 degrees or less, 250 degrees or less, 240 degrees or less, 230 degrees or less, 220 degrees or less, 210 degrees or less, 200 degrees or less, 190 degrees or less, 180 degrees or less, 170 degrees or less, 160 degrees or less, 150 degrees or less, 140 It may be less than or equal to, less than or equal to 130 degrees, less than or equal to 120 degrees, less than or equal to 110 degrees, less than or equal to 100 degrees, less than or equal to 90 degrees, less than or equal to 80 degrees, less than or equal to 70 degrees, or less than or equal to 60 degrees. In the above, the meaning of the alignment direction of the liquid crystal alignment film and a method for determining the same are as described above, and the twisting direction in the twist mode liquid crystal layer is analyzed using a measuring device such as Exoscan to analyze the rotation direction of the polarization source emitted from the variable transmittance layer It can be measured through. In the above case, the twisting direction may be clockwise or counterclockwise.

The arrangement of the retardation film may be controlled in consideration of the twist angle of the twist alignment mode, the refractive anisotropy of the transmittance variable layer (active liquid crystal layer) and / or the thickness of the variable layer (active liquid crystal layer) in another example. .

For example, when the twist angle of the twist alignment mode of the variable layer is within a range of 50 degrees to 180 degrees or 80 degrees to 180 degrees, a smaller angle among the angles formed by the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer or The angle formed by the slow axis and the alignment direction measured along the twisting direction of the twist alignment mode in the alignment direction of the liquid crystal alignment layer may satisfy Equation 1 below.

[Equation 1]

0.05 × △ nd × T / µm + 10 ≤ A ≤ 0.16 × △ nd × T / µm + 60

In Equation 1, A is a small angle among the angles formed by the alignment direction of the liquid crystal alignment layer or the angle between the slow axis and the alignment direction measured along the twisting direction of the twist alignment mode in the alignment direction of the liquid crystal alignment layer (unit : Degrees), Δn is the refractive index anisotropy of the variable layer (active liquid crystal layer) for light having a wavelength of 550 nm, d is the thickness of the liquid crystal layer (unit: μm), and T is the twist orientation mode. Twist angle (unit: degree).

The method of confirming the twisting direction of the twist orientation mode for confirming whether the above formula is satisfied is as described above, and the twist angle can be confirmed by the method of ~.

When Equation 1 is satisfied, the product (Δnd) of the refractive index anisotropy (Δn) for light having a wavelength of 550 nm of the liquid crystal layer and the thickness (d) of the liquid crystal layer may be 0.7 μm or less. The product (Δnd) of the refractive index anisotropy (Δn) and the thickness (d) of the liquid crystal layer is about 0.2 μm or more, 0.25 μm or more, 0.3 μm or more, 0.35 μm or more, 0.4 μm or more, or 0.45 μm or more in another example. You can.

In addition, the angle A in Equation 1 above is (0.05 × Δnd × T / μm + 11) or higher, (0.05 × Δnd × T / μm + 12) or higher, (0.05 × Δnd × T / μm) in another example. + 13) or more, (0.05 × △ nd × T / µm + 14) or more, (0.05 × △ nd × T / µm + 15) or more, (0.05 × △ nd × T / µm + 16) or more, (0.05 × △ nd × T / µm + 17) or higher, (0.05 × △ nd × T / µm + 18) or higher, (0.05 × △ nd × T / µm + 19) or higher, (0.05 × △ nd × T / µm + 20) ) Or (0.05 × Δnd × T / µm + 21) or more.

The angle A in Equation 1 is (0.16 × Δnd × T / μm + 55) or less, (0.16 × Δnd × T / μm + 50) or less, and (0.16 × Δnd × T / μm + 45) or less , (0.16 × △ nd × T / μm + 40) or less, (0.16 × △ nd × T / μm + 35) or less, (0.16 × △ nd × T / μm + 30) or less, (0.16 × △ nd × T / Μm + 25) or less, (0.16 × △ nd × T / μm + 20) or less, (0.16 × △ nd × T / μm + 15) or less, (0.16 × △ nd × T / μm + 10) or less, ( It may be about 0.16 × Δnd × T / µm + 5) or less or (0.16 × Δnd × T / µm + 1) or less.

In another example, when the twist angle of the twist alignment mode of the variable layer is within a range of 50 degrees to 180 degrees or 80 degrees to 180 degrees, a smaller angle or an angle formed between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer The angle between the slow axis and the alignment direction measured along the twisting direction of the twist alignment mode in the alignment direction of the liquid crystal alignment layer may satisfy Equation 2 below.

[Equation 2]

0.16 × △ nd × T / µm-10 ≤ A ≤ 0.16 × △ nd × T / µm + 20

In Equation 2, A is a small angle among the angles formed by the alignment direction of the liquid crystal alignment layer or the angle formed by the slow axis and the alignment direction measured along the twisting direction of the twist alignment mode in the alignment direction of the liquid crystal alignment layer (unit : Degrees), Δn is the refractive index anisotropy of the variable layer (active liquid crystal layer) for light having a wavelength of 550 nm, d is the thickness of the liquid crystal layer (unit: μm), and T is the twist orientation mode. Twist angle (unit: degree).

The twisting direction and the twisting method of the twist orientation mode for confirming whether the above formula is satisfied are as described above.

When Equation 2 is satisfied, the product (Δnd) of the refractive index anisotropy (Δn) for light having a wavelength of 550 nm of the liquid crystal layer and the thickness (d) of the liquid crystal layer may be greater than 0.7 μm. The product (Δnd) of the refractive index anisotropy (Δn) and the thickness (d) of the liquid crystal layer may be about 2 μm or less, 1.5 μm or less, or about 1 μm or less in another example.

In addition, the angle A in Equation 2 above is (0.16 × Δnd × T / μm −8) or higher, (0.16 × Δnd × T / μm-6) or higher, and (0.16 × Δnd × T / μm) in another example. -4) or higher, (0.16 × △ nd × T / μm-2) or higher, (0.16 × △ nd × T / μm) or higher, (0.16 × △ nd × T / μm + 2) or higher, (0.16 × △ nd XT / µm + 4) or higher (0.16 × Δnd × T / µm + 6) or higher.

In addition, the angle A in Equation 2 above is (0.16 × Δnd × T / μm + 18) or less, (0.16 × Δnd × T / μm + 16) or less, (0.16 × Δnd × T / μm + 14) ) Or less, (0.16 × △ nd × T / μm + 12) or less, (0.16 × △ nd × T / μm + 10) or less, (0.16 × △ nd × T / μm + 8) or less, (0.16 × △ nd × T / µm + 6) or less, (0.16 × △ nd × T / µm + 4) or less, (0.16 × △ nd × T / µm + 2) or less, or (0.16 × △ nd × T / µm) or less have.

In another example, when the twist angle of the twist alignment mode of the variable layer is 180 degrees or more or more than 180 degrees, a small angle or an orientation direction of the liquid crystal alignment layer among the angles formed by the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer The angle between the slow axis and the alignment direction measured along the twisting direction of the twist alignment mode satisfies Equation 3 below, or is greater among the angles formed by the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer. The angle between the slow axis and the alignment direction measured along the reverse direction of the twisting direction of the twist alignment mode in the alignment direction of the liquid crystal alignment layer may satisfy Equation 4 below.

[Equation 3]

A = (42 ± 5) + (17 ± 5) × sin (2 △ n × d × f)

[Equation 4]

A = (132 ± 5) + (17 ± 5) × sin (2 △ n × d × f)

In Equations 3 and 4, Δn is the refractive index anisotropy of the liquid crystal layer for light having a wavelength of 550 nm, d is the thickness of the liquid crystal layer (unit: μm), and f is the twist angle (unit: Degrees).

In addition, in Equation 3, A is smaller than the angle formed by the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer or the slow axis measured along the twisting direction of the twist alignment mode in the alignment direction of the liquid crystal alignment layer. The angle (unit: degree) formed by the alignment direction, and in Equation 4, A is a larger angle among the angles formed by the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer or the twist alignment mode in the alignment direction of the liquid crystal alignment layer The angle (unit: degree) between the slow axis and the orientation direction measured along the reverse direction of the twisting direction of.

The twisting direction and the twisting method of the twist orientation mode for confirming whether the above formula is satisfied are as described above.

When the equations 3 or 4 are satisfied, the twist angle may be about 600 degrees or less, 550 degrees or less, 500 degrees or less, 450 degrees or less, 400 degrees or less, 350 degrees or less, 300 degrees or less, 250 degrees or less, or 200 degrees or less. You can.

When Equation 3 or 4 is satisfied, the product (Δnd) of the refractive index anisotropy (Δn) for light having a wavelength of 550 nm of the liquid crystal layer and the thickness (d) of the liquid crystal layer is

When Equation 1 is satisfied, a product (Δnd) of refractive index anisotropy (Δn) for light having a wavelength of 550 nm of the liquid crystal layer and thickness (d) of the liquid crystal layer may be in a range of 0.2 μm to 2 μm. have. The product (Δnd) of the refractive index anisotropy (Δn) and the thickness (d) of the liquid crystal layer is about 0.25 μm or more, 0.3 μm or more, 0.35 μm or more, 0.4 μm or more, or 0.45 μm or more, or about 1.5 in another example. It may be less than or equal to about 1 μm or less.

In addition, the angle A in Equation 3 is (42 ± 4) + (17 ± 4) × sin (2Δn × d × f), (42 ± 3) + (17 ± 3) × sin (2) in another example. △ n × d × f), (42 ± 2) + (17 ± 2) × sin (2 △ n × d × f), (42 ± 1) + (17 ± 1) × sin (2 △ n × d × f) or (42 + 17 × sin (2Δn × d × f)), and the angle A in Equation 4 is (132 ± 4) + (17 ± 4) × sin (2 △ n) in another example. × d × f), (132 ± 3) + (17 ± 3) × sin (2 △ n × d × f), (132 ± 2) + (17 ± 2) × sin (2 △ n × d × f ), (132 ± 1) + (17 ± 1) × sin (2Δn × d × f) or (132 + 17 × sin (2Δn × d × f)).

By arranging the retardation film having the above-described large optical anisotropy in the above-described positional relationship, it is possible to provide a device having excellent transmittance variability and having no rainbow phenomenon, mirroring phenomenon, and crosstalk phenomenon.

As described above, the refractive index anisotropy (Δn) applied to the above-mentioned formulas is measured using an Abbe refractometer according to the method disclosed in Examples, and the thickness (d) of the liquid crystal layer, that is, a cell gap The measurement method of is also according to the method disclosed in the Examples.

The variable transmittance device of the present application includes the variable transmittance layer and the retardation film, and can be configured in various ways as long as the arrangement between them is controlled as mentioned above.

For example, basically, a variable transmittance layer, particularly an active liquid crystal layer, is positioned between two opposingly disposed substrates, in order to implement the device of the present application, any one of the two substrates is the retardation film described above. It can also be formed (first method).

Alternatively, the device of the present application may be implemented by attaching the retardation film to the outside of an element including a variable transmittance layer positioned between two opposingly disposed substrates (second method).

3 is an example of implementing a device according to the first method, and such devices include the phase difference film 100, the electrode layer 400, the alignment layer 300, the active liquid crystal layer 200, and the alignment layer sequentially arranged. 500, an electrode layer 400, and a substrate 600.

In addition, Figure 4 is an example of implementing a device according to the second method, such a device, the phase difference film 100, the substrate 600, the electrode layer 400, the alignment layer 300, the active liquid crystal sequentially arranged The layer 200, the alignment layer 500, the electrode layer 400 and the substrate 600 may be included.

That is, when the device is implemented in the first method, the retardation film is applied as a substrate, and the above-described liquid crystal alignment layer may be formed on the surface of the retardation film. When the device is implemented in the second method, the device is the liquid crystal. The alignment layer may further include a substrate formed on the surface, and the retardation film may be attached to a surface on which the liquid crystal alignment layer of the substrate is not formed.

The electrode layer 400 that may be included in the device is configured to apply power to the active liquid crystal layer 200 as an external signal, and as the electrode layer, a known transparent electrode layer can be applied. For example, a so-called conductive polymer layer, a conductive metal layer, a conductive nanowire layer or a metal oxide layer such as ITO (Indium Tin Oxide) may be used as the electrode layer. In addition, various materials and methods for forming a transparent electrode layer are known and can be applied without limitation.

As described above, as the liquid crystal alignment layer included in the device, a known rubbing alignment layer or a photo alignment layer may be applied, and the type of alignment layer that can be applied according to a desired mode is known.

The type of the substrate (reference numeral 600 in FIGS. 3 and 4) that can be applied in the device is not particularly limited. As the substrate, the above-described retardation film itself may be applied as a polymer film substrate, or other known substrates may be applied.

For example, an inorganic film such as a glass film, a crystalline or amorphous silicon film, quartz, or an indium tin oxide (ITO) film, a plastic film, or the like can be used as the substrate. As the plastic substrate, triacetyl cellulose (TAC); Cyclo olefin copolymer (COP) such as norbornene derivatives; PMMA (poly (methyl methacrylate); PC (polycarbonate); PE (polyethylene); PP (polypropylene); PVA (polyvinyl alcohol); DAC (diacetyl cellulose); Pac (Polyacrylate); PES (poly ether sulfone); PEEK (polyetheretherketon) ); PPS (polyphenylsulfone), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate) or an amorphous fluorine resin substrate may be used. It is not limited.

The device basically includes the above-described retardation film, liquid crystal alignment layer, and variable transmittance layer, and may further include various known configurations as long as their positional relationship is set as mentioned above.

For example, although not shown in the drawings, well-known structures, for example, the above-described substrate, a variable transmittance layer, and the like, may also include spacers or sealants that maintain a gap between the substrates.

In addition, as other components, adhesives or adhesives applied for the purpose of attaching the retardation film to the substrate or other uses, a hard coating layer, an anti-reflection layer, a layer including a dye having a near-infrared (NIR) cut function, etc. Additional configurations may be included. In addition, if necessary, the device may or may not include a passive polarizing layer such as a so-called passive polarizing layer, for example, a polarizing layer of poly (vinyl alcohol) (PVA) series.

The variable transmittance device as described above can be applied to various uses. Applications for which the variable transmittance device can be applied include openings in enclosed spaces, such as buildings or containers or vehicles, such as windows or sunroofs, or for eyewear or windows, and shading plates of organic light emitting deivce (OLED). And the like. The scope of the eyewear in the above includes all eyewear formed to allow an observer, such as general glasses, sunglasses, sports goggles or a wearable device such as a helmet or a device for virtual reality or augmented reality to observe the outside through the lens. You can.

Eyewear is a typical application to which the variable transmittance device of the present application can be applied. Recently, sunglasses, sports goggles, or augmented reality experience devices such as eyewear in which lenses are mounted so as to be inclined from an observer's front gaze are commercially available. The variable transmittance device of the present application can be effectively applied to the aforementioned eyewear.

When the variable transmittance device of the present application is applied to eyewear, the structure of the eyewear is not particularly limited. That is, the transmittance variable device may be mounted and applied in a lens for a left eye and / or a right eye of a known eyewear structure.

For example, the eyewear may include a left eye lens and a right eye lens; And a frame supporting the lens for the left eye and the lens for the right eye.

5 is an exemplary schematic diagram of the eyewear, a schematic diagram of the eyewear including the frame 82 and the lens 84 for the left eye and the right eye, or the structure of the eyewear to which the transmittance variable device of the present application can be applied. Is not limited to FIG. 5.

In the eyewear, the left-eye lens and the right-eye lens may each include the variable transmittance device. Such a lens may include only the variable transmittance device, or may include other configurations.

Other configurations or designs of the eyewear are not particularly limited, and a known method may be applied.

In this application, it is possible to provide a variable transmittance device capable of being applied to various uses without causing problems such as a crosstalk phenomenon, a rainbow phenomenon, or a mirroring phenomenon, while having excellent transmittance characteristics. .

1-4 are schematic diagrams of an exemplary variable transmittance device of the present application.
5 exemplarily shows eyewear.
6 is a schematic view for explaining a method for measuring the thickness (cell gap) of the variable transmittance film.
7 is a view for use in the process of measuring the thickness (cell gap) of the variable transmittance film.
8 is a view showing a method for evaluating refractive index anisotropy.
9 to 12 are views showing the results of Examples or Comparative Examples.

Although the present application is specifically described through the following examples, the scope of the present application is not limited by the following examples.

1. Evaluation of retardation of polymer film

The in-plane retardation value (Rin) of the polymer film was measured for light at a wavelength of 550 nm using Agilent's UV / VIS spectroscope 8453 equipment. After installing the two polarizers on the UV / VIS spectroscope so that the transmission axes are orthogonal to each other, and installing the polymer film between the two polarizers so that the slow axis of the polymer film is 45 degrees with the transmission axis of the two polarizers, then transmittance according to the wavelength. Was measured. The phase retardation order of each peak is obtained from the transmittance graph according to the wavelength. Specifically, in the transmittance graph according to the wavelength, the waveform satisfies Equation A below, and the maximum peak (Tmax) condition in the sine wave satisfies Equation B below. In the case of λmax in Equation A, T in Equation A and T in Equation B are the same, so Equation is developed. Formulas are also developed for n + 1, n + 2, and n + 3, and when n and n + 1 formulas are rearranged and R is eliminated, and n is divided into λn and λn + 1 formulas, the following formula C is derived. Since n and λ are known based on the same T in Equation A and T in Equation B, R is obtained for each of λn, λn + 1, λn + 2, and λn + 3. For 4 points, a straight trend line of the R value according to the wavelength is obtained, and the R value for the equation 550 nm is calculated. The function of the straight trend line is Y = ax + b, and a and b are constants. The Y value when 550 nm is substituted for x of the function is a Rin value for light having a wavelength of 550 nm.

[Formula A]

T = sin ² [(2πR / λ)]

[Formula B]

T = sin ² [((2n + 1) π / 2)]

[Formula C]

n = (λn -3λn + 1) / (2λn + 1 + 1-2λn)

In the above, R means an in-plane retardation (Rin), λ means a wavelength, and n means a vertex order of a sine wave.

2. Evaluation of the thickness of the variable transmittance layer (liquid crystal layer)

The thickness of the variable transmittance layer, that is, the cell gap (cell gap) was measured in the following manner using a spectrometer. As shown in FIG. 6, light I _I is irradiated from one surface of the variable transmittance layer having a cell gap d, and light I _T transmitted from the other surface is measured. When irradiating the light, the irradiation angle is made parallel to the virtual surface normal direction of the variable transmittance layer. When the transmittance for each wavelength is checked in this way, a transmittance graph as shown in FIG. 7 may be obtained due to constructive interference. The graph obtained as shown in FIG. 7 has a relationship between the cell gap (d), which is the thickness of the variable transmittance layer, and Equation E below. In Equation E below, κ is between the wavelengths λ ₁ and λ ₂ in FIG. 7. It is the number of peaks present in. That is, from the graph obtained as shown in FIG. 7, the number of peaks between the wavelengths λ ₁ and λ ₂ , which is κ, is obtained, and the cell gaps (d) can be obtained by substituting the wavelengths λ ₁ and λ ₂ into E. have.

[Formula E]

3. Evaluation of refractive index anisotropy of variable transmittance layer (liquid crystal layer)

The refractive index anisotropy (Δn) of the variable transmittance layer was evaluated in the following manner using an Abbe refractometer. If a vertical alignment layer is coated on the surfaces of the measuring prisms and illumination prisms of the Abbe refractometer, and the liquid crystal compound to be measured is applied to the measuring prisms and then covered with the illumination prisms, the liquid crystal compound is vertically aligned by the vertical alignment of the two interfaces. . The liquid crystal compound applied in the above process is only a liquid crystal compound to be applied to a variable transmittance layer not mixed with other materials such as dichroic dye.

Thereafter, as shown in FIG. 8, when a linear polarizing plate is applied to the eyepiece side and irradiated with light to observe, θe and θo as shown in FIG. 8 can be obtained, and the refractive index of the measuring prism (n _p ) And the above angles θe and θo, the ideal refractive index (n _e = n _p sinθe) and the normal refractive index (n _o = n _p sinθo) can be obtained, and the difference (n _e -n _o ) is defined as the refractive anisotropy Can be. The reference wavelength at the time of the measurement is approximately 550 nm.

Example 1.

As a polymer film substrate, a device was manufactured using Toyobo's highly stretched PET (Polyethylene terephthalate) film substrate (SRF substrate, thickness: 80 μm, manufacturer: Toyobo, product name: TA044). An indium tin oxide (ITO) film (electrode layer) was first deposited on one surface of the SRF substrate to form an alignment film. The SRF substrate applied in the above has an in-plane retardation of about 11,000 nm to 14,000 nm based on the 550 nm wavelength after the ITO film is deposited. As the alignment film, a polyimide-based horizontal alignment film (SE-7492, Nissan) having a thickness of approximately 300 nm was formed by rubbing with a rubbing cloth, wherein the rubbing direction (orientation direction) and the slow axis direction of the SRF substrate were approximately 12 clockwise. It was made to become a figure (upper board | substrate, manufacture of a viewing side board | substrate). Similarly, a lower substrate was prepared. The device was fabricated by arranging the upper substrate and the lower substrate so that the respective alignment films faced each other (cell gap: 6 μm), and sealing the liquid crystal material after injecting it therein.

In the above arrangement, the orientation directions of the lower substrate of the upper substrate were parallel to each other, and the rubbing directions were arranged to be opposite to each other. In addition, as the liquid crystal material, a chiral dopant (S811, Merck) in a GHLC mixture (MDA-16-1235, Merck) comprising a liquid crystal compound having a dielectric constant anisotropy with a refractive index anisotropy (Δn) of 0.13 and a dichroic dye Was used at a concentration of about 0.38% by weight. The obtained variable transmittance layer (liquid crystal layer) is a twist mode liquid crystal layer having a twisted angle of approximately 90 degrees, and the slow axis of the upper substrate (SRF substrate) and the liquid crystal alignment layer measured according to the twisting direction of the twist mode. The angle formed by the orientation direction of is approximately 12 degrees.

Comparative Example 1.

As a polymer film substrate, a device was manufactured in the same manner as in Example 1, except that a PC (Polycarbonate) film substrate (PC substrate, thickness: 100 μm, manufacturer: Teijin, product name: PFC100-D150), which is an isotropic film substrate, was applied. Did. In this case, since the applied film substrate is an isotropic film substrate, the relationship between the orientation direction of the alignment film and the slow axis of the substrate is not considered.

Test Example

In the examples and comparative examples, an absorption type linear PVA (poly (vinyl alcohol)) polarizer is disposed on the surface of the upper SRF substrate or PC substrate of each device, and light is emitted while rotating the absorption axis of the polarizer in a range of 0 degrees to 360 degrees. The change in the color coordinate (CIE La * b *) of the resulting light was measured. 9 is a comparison result of Example 1 and Comparative Example 1 as the measurement results as described above. In FIG. 9, SRF ITO_12 is Example 1 and PC_ITO is Comparative Example 1. It can be confirmed from the drawing that the change in the color coordinates (a * -b * color coordinates) in the case of Example 1 is significantly less than that of Comparative Example 1.

Example 2.

10 is a GHLC mixture (MDA-16) comprising a liquid crystal compound and a dichroic dye having a dielectric constant anisotropy with a positive refractive index anisotropy (Δn) of 0.13, in which a device is manufactured in the same manner as in Example 1 -1235, Merck) is a diagram showing the results in the case of using a liquid crystal material in which chiral dopants (S811, Merck) are blended, and the thickness of the liquid crystal layer, that is, a cell gap of 6 μm. In the drawing, the X-axis is the twist angle (T) of the device, and the Y-axis is the slow axis angle of the SRF substrate showing the smallest color coordinate change when the color coordinate change is measured in the same manner as in Test Example 1 at the twist angle (T). The slow axis angle of the SRF substrate is an angle formed by the slow axis of the upper substrate (SRF substrate) and the alignment direction of the liquid crystal alignment layer formed on the upper substrate, which is the alignment direction of the alignment layer as shown in Example 1 when manufacturing the device. You can adjust it by controlling. In addition, the twist angle (X-axis) can be controlled through the amount of chiral dopant added. The vertical scatter bar shown in the figure shows the optimal slow axis angle. It can be seen from the figure that the optimum angle is in accordance with the following Equation 1 when the twist angle is 180 degrees or less.

[Equation 1]

0.16 × △ nd × T / µm-10 ≤ A ≤ 0.16 × △ nd × T / µm + 20

In Formula 1, Δn is the refractive index anisotropy of the liquid crystal layer for light having a wavelength of 550 nm, and is 0.13 for Example 2, d is the thickness (unit: μm) of the liquid crystal layer, and for Example 2, 6 µm, and T is the twist angle (unit: degree) of the twist orientation mode.

Example 3.

11 is a GHLC mixture (SHN-5011XX) including a liquid crystal compound and a dichroic dye having a dielectric constant anisotropy with a positive refractive index anisotropy (Δn) of 0.076, in which a device is manufactured in the same manner as in Example 1. (JNC) as a dichroic dye, a mixture of LG Chem's dichroic dye (JD 12, a dye mixed with three dyes of cyan, magenta, and yellow color on the UK color systhesis solution) at a concentration of approximately 1.8 wt% ) Is a diagram showing the results when a liquid crystal material containing chiral dopants (S811, Merck) is used, and the thickness of the liquid crystal layer, that is, a cell gap is set to 11 μm. In the drawing, the X-axis is the twist angle (T) of the device, and the Y-axis is the slow axis angle of the SRF substrate showing the smallest color coordinate change when the color coordinate change is measured in the same manner as in Test Example 1 at the twist angle (T). The slow axis angle of the SRF substrate is an angle formed by the slow axis of the upper substrate (SRF substrate) and the alignment direction of the liquid crystal alignment layer formed on the upper substrate, which is the alignment direction of the alignment layer as shown in Example 1 when manufacturing the device. You can adjust it by controlling. In addition, the twist angle (X-axis) can be controlled through the amount of chiral dopant added. The vertical scatter bar shown in the figure shows the optimal slow axis angle. It can be seen from the figure that the optimum angle is in accordance with Equation 1 of Example 2 when the twist angle is 180 degrees or less.

Example 4.

12 is a GHLC mixture (SHN-5011XX) comprising a liquid crystal compound and a dichroic dye having a dielectric constant anisotropy with a positive refractive index anisotropy (Δn) of 0.076, wherein the device is manufactured in the same manner as in Example 1. (JNC) as a dichroic dye, a mixture of LG Chem's dichroic dye (JD 12, a dye mixed with three dyes of cyan, magenta, and yellow color on the UK color systhesis solution) at a concentration of approximately 1.8 wt% ) Is a diagram showing the results when a liquid crystal material containing chiral dopants (S811, Merck) is used, and the thickness of the liquid crystal layer, that is, a cell gap is set to 12 μm. In the drawing, the X-axis is the twist angle (T) of the device, and the Y-axis is the slow axis angle of the SRF substrate showing the smallest color coordinate change when the color coordinate change is measured in the same manner as in Test Example 1 at the twist angle (T). The slow axis angle of the SRF substrate is an angle formed by the slow axis of the upper substrate (SRF substrate) and the alignment direction of the liquid crystal alignment layer formed on the upper substrate, which is the alignment direction of the alignment layer as shown in Example 1 when manufacturing the device. You can adjust it by controlling. In addition, the twist angle (X-axis) can be controlled through the amount of chiral dopant added. The vertical scatter bar shown in the figure shows the optimal slow axis angle. It can be seen from the figure that the optimum angle is in accordance with Equation 1 of Example 2 when the twist angle is 180 degrees or less.

Claims (11)

A retardation film having an in-plane retardation of 5,000 nm or more for light having a wavelength of 550 nm; Liquid crystal alignment film; And a liquid crystal layer capable of implementing a twist alignment mode in the above order,
The twist angle of the twist orientation mode is within a range of 50 degrees to 180 degrees,
The product (Δnd) of the refractive index anisotropy (Δn) for light at a wavelength of 550 nm of the liquid crystal layer and the thickness (d) of the liquid crystal layer exceeds 0.7 μm,
Among the angles formed by the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer, a small angle A satisfies Equation 1 below:
[Equation 1]
0.16 × △ nd × T / ㎛-10 ≤ A ≤ 0.16 × △ nd × T / ㎛ + 20
In Equation 1, Δn is the refractive index anisotropy of the liquid crystal layer for light having a wavelength of 550 nm, d is the thickness of the liquid crystal layer (unit: μm), and T is the twist angle of the twist alignment mode (unit: degree). to be. The variable transmittance device according to claim 1, wherein a ratio (Tmax / Tmin) of the maximum transmittance (Tmax) and the minimum transmittance (Tmin) is within a range of 1.5 to 10. The transmittance variable device according to claim 1, wherein the angle A is an angle measured along the twisting direction of the twist alignment mode in the alignment direction of the liquid crystal alignment film. The transmittance variable device according to claim 3, wherein the twisting direction is clockwise or counterclockwise. The transmittance variable device according to claim 1, wherein the liquid crystal alignment film is formed on a surface of the retardation film. The transmittance variable device according to claim 1, wherein the liquid crystal alignment film further comprises a substrate formed on its surface, and the retardation film is attached to a surface on which the liquid crystal alignment film of the substrate is not formed. The transmittance variable device according to claim 1, wherein the twist orientation mode is a horizontal twist orientation mode or an inclined twist orientation mode. The device of claim 1, wherein the liquid crystal layer comprises a dichroic dye. The variable transmittance device according to claim 1, wherein the liquid crystal layer contains a chiral agent. The transmittance variable device according to claim 1, wherein a thickness of the liquid crystal layer is 20 µm or less. Left-eye and right-eye lenses; And a frame supporting the lens for the left eye and the lens for the right eye,
Each of the left-eye lens and the right-eye lens includes the variable transmittance device of claim 1.

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