KR102437159B1 - Transmission Variable Device - Google Patents

Abstract

The present application relates to a transmittance variable device. In the present application, it is possible to provide a variable transmittance device that has excellent transmittance variable characteristics and does not cause problems such as crosstalk, rainbow, or mirroring, which can be applied to various purposes. .

Description

Transmission Variable Device

This application relates to a transmittance variable device.

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

The use of these devices is gradually expanding, and for example, the devices include eyewear such as glasses or sunglasses, a mobile device, a virtual reality (VR) device, or an augmented reality (AR: Augmented Reality) device. ) can be used for wearable devices such as devices or vehicle windows, or devices that are applied outdoors.

In the case of a device that adjusts transmittance by applying a liquid crystal compound, polarization above a certain level is basically generated. In such a device, crosstalk (crosstalk) is caused by the reflection of a road surface, a structure, or a building having some polarization according to the usage environment. ) phenomenon, a rainbow phenomenon, or a mirroring phenomenon, and the like.

European Patent Publication No. 0022311

The present application relates to a transmittance variable device. An object of the present application is to provide a variable transmittance device that does not cause problems such as a crosstalk phenomenon, a rainbow phenomenon, or a mirroring phenomenon, and can be applied to various purposes.

The angle defined herein should be understood in consideration of errors such as manufacturing errors or variations. For example, the term vertical, parallel, perpendicular or horizontal in this specification means substantially vertical, parallel, orthogonal or horizontal in a range that does not impair the intended effect, for example, in each of the above cases, about An error within ±10 degrees, an error within about ±5 degrees, an error within about ±3 degrees, an error within about ±2 degrees, an error within about ±1 degree, or an error within about ±0.5 degrees may be included. have.

Among the physical properties mentioned in the present specification, when the measured temperature affects the corresponding physical property, unless otherwise specified, the physical property is a physical property measured at room temperature.

As used herein, the term room temperature is a temperature in a state in which the temperature is not particularly heated or reduced, and any one temperature within the 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 less while being more than ℃. In addition, unless otherwise specified, the unit of temperature referred to in this specification is °C.

The retardation, 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, the angle formed by any two directions mentioned herein may be an acute angle among acute to obtuse angles formed by the two directions, or a smaller angle among angles measured in a clockwise direction and a counterclockwise direction. . Accordingly, unless otherwise specified, angles referred to herein are positive numbers. However, in some cases, in order to indicate the measurement direction between the angles measured in the clockwise or counterclockwise direction, the angle measured in the clockwise direction may be expressed 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 aforementioned crosstalk phenomenon, rainbow phenomenon or mirroring phenomenon.

In the present application, the term variable transmittance device may refer to a device capable of switching between at least two or more different states of light. In the above, different states of light may mean states having at least different transmittances.

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

Transmittance of the variable transmittance device in the transmission mode state is at least 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65 % or more, 70% or more, 75% or more, or 80% or more. In addition, the transmittance of the variable transmittance device in the blocking mode state 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 transmission mode, the higher the transmittance, the more advantageous, and the lower the transmittance in the blocking mode. The upper limit of the transmittance may be about 100%, and the lower limit of the transmittance in the blocking mode state may be about 0%.

In one example, in the transmittance variable device capable of switching between the transmissive mode state and the blocking mode state, the difference between the transmittance in the transmissive mode state and the transmittance in the blocking mode state (transmissive mode - blocking mode) 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.

Also, in one example, a ratio (Tmax/Tmin) of the maximum transmittance (Tmax) in the transmission mode state and the minimum transmittance (Tmin) in the cut-off mode state may be in the range of about 1.5 to 10. In another example, 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, 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 straight light transmittance is a percentage of the ratio of the light transmitted in the same direction as the incident direction to the light incident on the device. For example, if the device is in the form of a film or sheet, the transmittance is defined as the percentage of light that has passed through the device in a direction parallel to the normal direction among the light incident in a direction parallel to the normal direction of the film or sheet surface. can

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

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

The switching of the transmittance variable device as described above may be adjusted according to the application of an external signal, for example, whether a voltage signal is applied. For example, in a state where there is no application of an external signal such as a voltage, the transmittance variable device maintains any one of the states described above, and may be switched to another state when a voltage is applied. By changing the strength, frequency and/or shape of the applied voltage, the state of the mode may be changed, or the third other mode state may be implemented.

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

In the present application, the term active liquid crystal layer is a layer including at least a liquid crystal compound, and may refer to a liquid crystal layer capable of controlling the alignment state of the liquid crystal compound through popularity of an external signal or the like. However, the application of the active liquid crystal layer is an 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. may also be used.

The active liquid crystal layer is a layer containing a liquid crystal compound. In the present specification, the range of the term active liquid crystal layer includes a layer including a liquid crystal compound capable of controlling its orientation through the application of an external signal, etc. For example, as described below, the liquid crystal compound (liquid crystal host) and A so-called guest host layer including a dichroic dye is also a kind of a liquid crystal layer defined in this specification. As the liquid crystal compound, any kind of liquid crystal compound may be used as long as its alignment direction can be changed by application of an external signal. For example, as the 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 crosslinkable group so that the alignment direction thereof can be changed by application of an external signal.

Whether the liquid crystal layer includes a liquid crystal compound having a positive or negative dielectric anisotropy, or the liquid crystal layer may exhibit the above-mentioned dielectric anisotropy. The absolute value of the dielectric anisotropy may be appropriately selected in consideration of the purpose of the present application. The term “dielectric anisotropy (Δε)” may mean a difference (ε// - ε⊥) between a horizontal dielectric constant (ε//) and a vertical dielectric constant (ε⊥). As used herein, the term horizontal permittivity (ε//) refers to 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 is substantially horizontal, The perpendicular permittivity (ε⊥) refers to 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 applied voltage is substantially perpendicular to the direction of the liquid crystal molecules.

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 above-mentioned refractive index anisotropy. The refractive index anisotropy (nΔ) referred to in the present application is a difference (ne-no) between an extraordinary refractive index (ne, extraordinary refractive index) and an ordinary refractive index (no, ordinary refractive index), which can be confirmed using an Abbe refractometer, A specific manner follows the method disclosed in the following examples.

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

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

In one example, the transmittance variable 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" refers to a functional layer in which dichroic dyes are arranged together according to the arrangement of liquid crystals, and each exhibits anisotropic light absorption characteristics with respect to the alignment direction of the dichroic dye and the direction perpendicular to 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 if the absorption rate of light polarized in the short-axis direction is large, it is called an n-type dye. can be called In one example, when a p-type dye is used, polarized light vibrating in the long-axis direction of the dye is absorbed, and polarized light vibrating in the short-axis direction of the dye is absorbed and transmitted therethrough. Hereinafter, it is assumed that the dichroic dye is a p-type dye, unless otherwise specified.

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

The light modulation film layer including the guest host liquid crystal layer as a transmittance variable layer may function as an active polarizer. As used herein, the term “active polarizer” may refer to a functional device capable of controlling anisotropic light absorption according to application of an external signal. Such an active polarizer may be distinguished from a passive polarizer, which will be described later, which has constant light absorption or light reflection characteristics regardless of external signal application. The guest host liquid crystal layer may control anisotropic light absorption with respect to polarization in a direction parallel to the arrangement direction of the dichroic dye and polarization in a direction perpendicular to the arrangement direction of the dichroic dye by adjusting the arrangement of the liquid crystal and the dichroic dye. Since the arrangement of the liquid crystal and the dichroic dye can be controlled by 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 inclined alignment mode and another state. The meanings of the vertical, horizontal and oblique orientation modes are in accordance with known content.

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

In addition, for example, the term vertical alignment state is a state in which the director of the active liquid crystal layer, which is the transmittance variable layer, or the director of the liquid crystal compound in the liquid crystal layer is approximately 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, About 90 degrees can be achieved.

In addition, for example, the term oblique alignment state is an alignment state between the vertical alignment state and the horizontal alignment state, and the direction of the variable layer (liquid crystal layer) from the side of the variable layer (liquid crystal layer) or the The angle between the direction of the liquid crystal compound in the liquid crystal layer and the variable layer (liquid crystal layer) is greater than 0 degrees and less than 90 degrees, or may mean a case in the range of about 10 degrees to 80 degrees.

In the present specification, the liquid crystal molecule or the director of the liquid crystal compound may refer to 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 have a rod shape, and may mean an axis in a normal direction to the plane of the disk when the liquid crystal molecules have a discotic shape. When a plurality of liquid crystal compounds having different directors exist in the active liquid crystal layer, the directors are vector sums.

In one example, the active liquid crystal layer, which is the transmittance variable layer, may be designed to implement at least a twisted alignment mode. The term twist alignment mode may refer to a spiral structure in which the directors of liquid crystal compounds are oriented in layers while twisting along an imaginary spiral axis in the liquid crystal layer. The twist alignment mode may be implemented in the aforementioned vertical, horizontal or oblique alignment mode, that is, the vertical twist alignment mode is a state in which individual liquid crystal compounds are twisted along a spiral axis in a vertically aligned state to form a layer, The twist alignment mode is a state in which individual liquid crystal compounds are horizontally aligned and twisted along the spiral axis to form a layer, and the oblique twist alignment mode is a state in which individual liquid crystal compounds are twisted along the spiral axis in a tilted alignment state to form layers. .

In the twist alignment mode, the ratio (d/p) of the thickness (d) to the pitch (p) of the liquid crystal layer may be 1 or less. If the ratio (d/p) exceeds 1, since there may be a problem that a finger domain or the like occurs, it may be adjusted within the above range as much as possible. The lower limit of the ratio (d/p) is not particularly limited, but may be greater than or equal to about 0.6 or greater than about 0.6. In the above, the thickness (d) of the liquid crystal layer may have the same meaning 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, D. Podolskyy et al. 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 may 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, 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 a desired twisting without impairing liquid crystallinity, for example, nematic regularity. can be used The chiral agent for inducing rotation in the liquid crystal molecules needs to contain at least chirality in the molecular structure. The chiral agent is, 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 cumulene ) or a compound having an axially asymmetric, optically active site having an axial agent such as binaphthol may be exemplified. The chiral agent may be, for example, a low molecular weight compound having a molecular weight of 1,500 or less. As the 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 may be used.

The rate of application of the chiral agent is not particularly limited to that selected so as to achieve the desired ratio (d/p). In general, the content (wt%) 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 with reference to this method. .

The thickness of the transmittance variable layer may be appropriately selected in consideration of the purpose of the present 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, 8 μm or more. or more, 9 μm or more, or 10 μm or more. By controlling the thickness in this way, it is possible to implement a device having a large difference in transmittance depending on the mode state. The thickness is not particularly limited as it is possible to implement a difference in high transmittance and/or reflectance as the thickness increases, but generally may be 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 shows the retardation film 100 and the variable layer 200 sequentially arranged as a schematic diagram of a device according to an example of the present application.

In the present application, as the retardation film, it is possible to provide a device without a so-called rainbow phenomenon, a mirroring phenomenon, and a crosstalk phenomenon by disposing a film having a large optical anisotropy at a specific position. Incidentally, by applying a film that is anisotropic in terms of mechanical properties as the retardation film, a device having excellent mechanical properties can also be configured.

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 description, the optically anisotropic phase of the retardation film refers to a case having an in-plane retardation to be described later, and anisotropic in terms of mechanical properties refers to a case in which the retardation film has physical 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 in which an electrode layer is formed on one surface of the retardation film. In this case, the electrode layer may be an electrode layer formed in a state in which the retardation film is included in the optical device.

Measurement of the physical properties of each retardation film mentioned in the present specification is measured according to the method described in the Examples section of the present 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 the present specification, the in-plane retardation 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, which 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. m or more or on the order of 15,000 m or more. In addition, the in-plane retardation of each of the retardation films is 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 a film having such a large retardation, a film known as a so-called highly stretched poly(ethylene terephthalate) (PET) film or SRF (Super Retardation Film) is typically known. Accordingly, in the present application, the retardation film may be, for example, a polyester film.

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

In one example, the retardation film may have a ratio (E1/E2) of an elongation (E1) in an arbitrary first direction in a plane and an elongation (E2) in a second direction perpendicular to the first direction (E1/E2) is 3 or more. . In another example, 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. 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 another example.

In this specification, the first direction, the second direction and the third direction of the retardation film are arbitrary 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 MD (Machine Direction) and TD (transverse direction) directions of the retardation film. In one example, the first direction described herein may be any one of a slow axis and a fast axis direction of the retardation film, and the second direction may be the other one of the slow axis and the fast axis direction. In another example, the first direction is any one of MD (Machine Direction) and TD (transverse direction) directions when the retardation film is a stretched retardation film, and the second direction is MD (Machine Direction) and TD (transverse direction) ) may be the other one of the directions.

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

The elongation of the retardation film in the first direction (eg, the aforementioned slow axis direction or the TD direction) 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 (E3) in the first and second directions and an angle in a range of 40 to 50 degrees or an elongation (E3) in the third direction forming about 45 degrees, respectively, in the first direction (E1) ), and the ratio (E3/E2) of the elongation E3 in the third direction to the elongation E2 in the second direction may be 5 or more.

In another example, 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, and is about 20 or less, 18 or less, 16 or less, 14 or less, 12 or less, or 10 or less.

The elongation of the retardation film in the third direction 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.

The retardation film may have a ratio (CTE2/CTE1) of a coefficient of thermal expansion (CTE2) in the second direction to a coefficient of thermal expansion (CTE1) in the first direction of 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 another example.

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/°C or more, 15 ppm/°C or more, 20 ppm/°C or more, 25 ppm/°C or more, 30 ppm/°C or more, 35 ppm/°C or more, 40 ppm/°C or more, 45 ppm at least /°C, at least 50 ppm/°C, at least about 55 ppm/°C, at least 60 ppm/°C, at least 65 ppm/°C, at least 70 ppm/°C, at least 75 ppm/°C, or at least 80 ppm/°C, or at least 140 ppm/°C ℃ or less, 130 ppm/℃ or less, 120 ppm/℃ or less, 100 ppm/℃ or less, 95 ppm/℃ or less, 90 ppm/℃ or less, 85 ppm/℃ or less, 80 ppm/℃ or less, 40 ppm/℃ or less , 30 ppm/℃ or less or 25 ppm/℃ or less.

In the retardation film, the ratio (YM1/YM2) of the elastic modulus YM2 in the second direction to the elastic modulus YM1 in the first direction may be 1.5 or more. In another example, 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.

The elastic modulus YM1 in the first direction may be in the range of about 2 to 10 GPa. The modulus of elasticity (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 or more Hereinafter, it may be 7.5 GPa or less, 7 GPa or less, 6.5 GPa or less, or 6 GPa or less.

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

In the retardation film, a ratio (MS1/MS2) of the maximum stress MS2 in the second direction to the maximum stress MS1 in the first direction may be 1.5 or more. In another example, 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.

The maximum stress MS1 in the first direction (eg, the aforementioned slow axis direction or the TD direction) may be in a range of about 80 to 300 MPa. The maximum stress (MS1) is, 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, 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.

As described above, a representative example of a polymer film having such large optical and mechanical asymmetry is a stretched polyethyleneterephtalate (PET) film known as a so-called highly stretched polyester film, and such a film can be easily obtained in the industry.

Generally, a stretched PET film is a uniaxially oriented film of one or more layers prepared by forming a film by melting/extrusion of a PET-based resin and stretching, or a biaxially oriented film of one or more layers prepared by stretching longitudinally and transversely after forming a film.

The PET-based resin usually means a resin in which 80 mol% or more of the repeating unit is made of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. Although it does not specifically limit as another dicarboxylic acid component, For example, isophthalic acid, p-beta- oxyethoxy benzoic 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, an ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol and/or polytetramethylene glycol, etc. can be heard

The said dicarboxylic acid component and diol component can be used combining 2 or more types as needed. 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, a carbonate bond, or the like, or a diol component may be used.

As a manufacturing method of a PET-type resin, a method of directly polycondensing terephthalic acid, ethylene glycol and/or other dicarboxylic acid or other diol as needed, a dialkyl ester of terephthalic acid and ethylene glycol and/or other dicarboxylic acids as needed A method of polycondensing a dialkyl ester of an acid or another diol after transesterification, and a method of polycondensing terephthalic acid and/or an ethylene glycol ester of another dicarboxylic acid and/or another diol ester if necessary method and the like are 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 above-mentioned complex compound can be used.

Polymerization reaction conditions can be appropriately selected depending on the monomers, catalysts, reaction equipment used, and the desired resin properties, and are not particularly limited, but for example, the reaction temperature is usually about 150° C. to about 300° C., about 200° C. to about 300°C or from 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 latter half of the reaction.

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

The polymerization apparatus may be one in which one reaction tank is completed, or a plurality of reaction tanks may be connected. In this case, the reactants are polymerized while being transferred between the reaction tanks according to the polymerization degree. In addition, it is also possible to employ a method of volatilizing while heating/kneading in which a horizontal reaction device is provided in the latter half of polymerization.

After polymerization, the resin is discharged from the reactor or horizontal reactor in a molten state, and then in the form of flakes that are cooled and pulverized on a cooling drum or a cooling belt, etc. is obtained Moreover, solid-state polymerization can be performed as needed, and molecular weight can also be improved or a low molecular-weight component can also be reduced. Examples of the low molecular weight component that can be contained 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 resin is usually 0.45 to 1.0 dL/g, 0.50 to 1.0 dL/g, when the resin is dissolved in a mixed solvent of phenol/tetrachloroethane = 50/50 (weight ratio) and expressed as an intrinsic viscosity measured at 30°C. 10 dL/g or in the range of 0.52 to 0.80 dL/g.

In addition, the PET-based resin may contain additives as needed. As an additive, a lubricant, an antiblocking agent, a heat stabilizer, antioxidant, an antistatic agent, a light resistance agent, an impact resistance improving agent, etc. are mentioned, for example. It is preferable that the amount added is within a range that does not adversely affect optical properties.

PET-based resins are usually used in the form of pellets granulated by an extruder for blending these additives and for film forming to be described later. Although the size or shape of the pellets is not particularly limited, they are usually cylindrical, spherical, or flat spherical in height and diameter of 5 mm or less. The PET-type resin obtained in this way can be shape|molded into a film form, and it can be set as a PET film with high mechanical strength by shape|molding and extending|stretching process. Although it does not specifically limit as the manufacturing method, For example, the method described below is employ|adopted.

The dried pellets made of PET resin are fed to a melt-extrusion apparatus, heated to a melting point or higher, and melted. Next, the molten resin is extruded from a die and quenched and solidified to a temperature below the glass transition temperature on a rotating cooling drum to obtain an unstretched film in a substantially amorphous state. This melting temperature is determined according to the melting point of the PET-based resin used or the extruder, 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 rotating cooling drum, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. In the electrostatic application adhesion method, a linear electrode is usually installed on the upper surface of the film in a direction orthogonal to the flow of the film, and a DC voltage of about 5 to 10 kV is applied to the electrode to provide an electrostatic charge to the film, and rotational cooling This is a method of improving the adhesion between the drum and the film. In addition, the liquid coating adhesion method is a method of improving the adhesion between the rotary cooling drum and the film by uniformly applying the liquid to the entire or part of the surface of the rotary cooling drum (eg, only the portion in contact with both ends of the film). Both may be used in combination as needed. The PET-based resin used may be mixed with two or more types of resins and resins having different structures or compositions as needed. For example, mixing and using the pellet with which the granular filler as an antiblocking agent, an ultraviolet absorber, an antistatic agent, etc. were mix|blended, and the pellet of non-blending, etc. are mentioned.

In addition, the number of lamination|stacking of the film to be extruded can also be made into two or more layers as needed. For example, prepare pellets blended with a granular filler as an anti-blocking agent and unblended pellets, and feed it from another extruder to the same die to make a film consisting of two types and three layers of "filler blended / unblended / filler blended" Extrusion, etc. are mentioned.

The unstretched film is usually longitudinally stretched first in the extrusion direction at a temperature equal to or higher than the glass transition temperature. The stretching temperature is usually 70°C to 150°C, 80 to 130°C, or 90 to 120°C. Moreover, a draw ratio is 1.1 to 6 times or 2 to 5.5 times normally. Extending|stretching may be completed by one time, and may be divided and performed into multiple times as needed.

The vertically stretched film obtained in this way can be heat-processed after that. Next, you may perform a relaxation process as needed. 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. Incidentally, the relaxation amount is usually 0.1 to 20% or 2 to 5%. The temperature and the relaxation amount of this relaxation treatment can set the amount of relaxation and the temperature at the time of a relaxation treatment so that the thermal contraction rate at 150 degreeC of the PET film after a relaxation treatment may be 2 % or less.

In the case of obtaining a uniaxially stretched or biaxially stretched film, transverse stretching is usually performed by a tenter after longitudinal stretching treatment, or after thermal 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. Moreover, a draw ratio is 1.1 to 6 times or 2 to 5.5 times normally. Thereafter, heat treatment and, if necessary, relaxation treatment can be performed. 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. The relaxation amount is usually 01 to 20%, 1 to 10%, or 2 to 5%. The temperature and the amount of relaxation of this relaxation treatment can be set so that the thermal contraction rate at 150° C. of the PET film after the relaxation treatment is 2% or less, the amount of relaxation and the temperature at the time of the relaxation treatment.

In the uniaxial stretching and biaxial stretching treatment, after transverse stretching, in order to relieve deformation of the main axis of orientation as typified by bowing, heat treatment or stretching treatment may be performed again. The maximum value of the deformation in the direction of elongation of the orientation main axis by bowing is usually within 45 degrees, within 30 degrees, or within 15 degrees. In addition, the extending|stretching direction means here the extending|stretching direction large in longitudinal stretch or lateral stretch.

In the biaxial stretching of a PET film, the case of a transverse stretch magnification is usually performed slightly larger than a longitudinal stretch magnification, and in this case, an extending|stretching direction means a direction perpendicular|vertical with respect to the longitudinal direction of the said film. In addition, in uniaxial stretching, it is normally extended|stretched in the transverse direction as mentioned above, and in this case, an extending|stretching direction means a direction perpendicular|vertical with respect to a longitudinal direction similarly.

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

The confirmation direction of the orientation main axis is known, for example, it can be measured using a retardation film/optical material inspection device RETS (manufactured by Otsuka Electronics Co., Ltd.) or a molecular orientation meter MOA (manufactured by Oji Corporation). can

Functional layers other than the anti-glare layer may be laminated on one side or both sides of the stretched PET film as long as the effect of the present application is not hindered. Examples of the laminated functional layer include a conductive layer, a hard coat layer, a smoothing layer, a lubricating layer, an anti-blocking layer, and an easily bonding layer.

The above-described manufacturing method is an exemplary method for obtaining the retardation film of the present application, and any kind of commercially available retardation film may be used as long as the retardation film applicable in the present application has the above-described physical properties.

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

In one example, the device may include a liquid crystal alignment film to be described later between the retardation film and the transmittance variable layer. In this case, the angle between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment film is 0 degrees to 70 degrees. 2 is a schematic diagram in the case where the retardation film 100, the liquid crystal alignment layer 300, and the transmittance variable layer 200 are sequentially disposed in the above example. The angle is a smaller angle among the angles between the orientation direction and the slow axis, and may be in the range of 0 degrees to 360 degrees in one example. In another example, 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, 22 degrees or more, 24 degrees or more, 26 or more degrees, 28 degrees or more, 30 degrees or more, 32 degrees or more, 34 degrees or more, 36 degrees or more, 38 degrees or more, 40 degrees or more, 42 degrees or more, 44 degrees or more, 46 degrees or more or more, 48 degrees or more, or 50 degrees or more, or less than 360 degrees, 350 degrees or less, 340 degrees or less, 330 degrees or less, 320 degrees or less, 310 degrees or less, 300 degrees or less, 290 degrees or less, 280 degrees or less, 270 degrees or less , 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 The degree may be less than or equal to 130 degrees, less than 120 degrees, less than 110 degrees, less than 100 degrees, less than 90 degrees, less than 80 degrees, less than 70 degrees, or less than 60 degrees. The liquid crystal alignment layer may be used to determine the initial alignment of the liquid crystal in the liquid crystal layer when the transmittance variable layer is an active liquid crystal layer. The type of the liquid crystal alignment layer applied at this time is not particularly limited, and may be, for example, a known rubbing alignment layer or a photo-alignment layer. As will be described later, there are cases in which alignment layers are present on both sides of the active liquid crystal layer. In this case, the alignment layer having the alignment direction at the angle with the slow axis of the retardation film is the alignment direction of the alignment layer located close to the retardation film. The alignment direction may be a rubbing direction in the case of a rubbing alignment layer and a direction of polarized light to be irradiated in the case of a photo-alignment layer, and this alignment direction may be confirmed by a detection method using a linear polarizer. For example, when the liquid crystal layer (transmittance variable layer) is in a twisted alignment mode such as STN (Super Twisted Nematic) mode, a linear polarizer is disposed on one surface and transmittance is measured while changing the absorption axis of the polarizer, the absorption axis Alternatively, when the transmission axis and the alignment direction of the liquid crystal alignment layer coincide, the transmittance tends to be low, and the alignment direction can be confirmed through simulation reflecting the refractive index anisotropy of the applied liquid crystal compound. A method of confirming the alignment direction according to the mode of the liquid crystal layer (transmittance variable layer) is known, and in the present application, an angle between the alignment direction of the liquid crystal alignment layer and the slow axis can be confirmed in this known method.

In another example, when the transmittance variable layer is an active liquid crystal layer capable of implementing the twist alignment mode described above, the angle formed between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer is the twist alignment 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 so as to be in the range of 0 degrees to 360 degrees. In another example, 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, 22 degrees or more, 24 degrees or more, 26 or more degrees, 28 degrees or more, 30 degrees or more, 32 degrees or more, 34 degrees or more, 36 degrees or more, 38 degrees or more, 40 degrees or more, 42 degrees or more, 44 degrees or more, 46 degrees or more or more, 48 degrees or more, or 50 degrees or more, or less than 360 degrees, 350 degrees or less, 340 degrees or less, 330 degrees or less, 320 degrees or less, 310 degrees or less, 300 degrees or less, 290 degrees or less, 280 degrees or less, 270 degrees or less , 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 The degree may be less than or equal to 130 degrees, less than 120 degrees, less than 110 degrees, less than 100 degrees, less than 90 degrees, less than 80 degrees, less than 70 degrees, or less than 60 degrees. The meaning of the alignment direction of the liquid crystal alignment layer and the method for determining it are the same as described above. In the liquid crystal layer in twist mode, the twist direction is analyzed using a measuring device such as Exoscan to analyze the rotation direction of the polarization source emitted from the transmittance variable layer can be measured through In the above case, the twisting direction may be a clockwise direction or a counterclockwise direction.

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

For example, when the twist angle of the twist alignment mode of the variable layer is in the range of 50 degrees to 180 degrees or 80 degrees to 180 degrees, the smaller angle between the slow axis of the retardation film and the orientation direction of the liquid crystal alignment layer An 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 1 below.

[Formula 1]

0.05×Δnd×T/㎛ + 10 ≤ A ≤ 0.16 ×Δnd×T/㎛ + 60

In Equation 1, A is a smaller angle among the angles formed by the alignment direction of the liquid crystal alignment layer or the angle formed 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 550 nm wavelength light of the variable layer (active liquid crystal layer), d is the thickness of the liquid crystal layer (unit: μm), and T is the twist alignment mode of the Twist angle (in degrees).

The confirmation method of the twist direction of the twist orientation mode for confirming whether the above formula is satisfied is the same as described above, and the twist angle can be confirmed in the manner of .

When Equation 1 is satisfied, the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer with respect to light having a wavelength of 550 nm 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. can

In addition, the angle A in Equation 1 is (0.05×Δnd×T/㎛ + 11) or more, (0.05×Δnd×T/㎛+12) or more, and (0.05×Δnd×T/㎛) in another example + 13) or more, (0.05×Δnd×T/㎛ + 14) or more, (0.05×Δnd×T/㎛ + 15) or more, (0.05×Δnd×T/㎛ + 16) or more, (0.05× △nd×T/㎛ + 17) or more, (0.05×Δnd×T/㎛ + 18) or more, (0.05×Δnd×T/㎛ + 19) or more, (0.05×Δnd×T/㎛ + 20) ) or more or (0.05×Δnd×T/㎛ + 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, (0.16×Δnd×T/μm + 45) or less , (0.16×Δnd×T/㎛ + 40) or less, (0.16×Δnd×T/㎛ + 35) or less, (0.16×Δnd×T/㎛ + 30) or less, (0.16×Δnd×T /μm + 25) or less, (0.16×Δnd×T/μm + 20) or less, (0.16×Δnd×T/μm + 15) or less, (0.16×Δnd×T/μm + 10) or less, ( 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 in the range of 50 degrees to 180 degrees or 80 degrees to 180 degrees, the smaller angle among the angles 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×Δnd×T/㎛ - 10 ≤ A ≤ 0.16 ×Δnd×T/㎛ + 20

In Equation 2, A is a smaller angle among the angles formed by the alignment direction of the liquid crystal alignment layer or the angle formed 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 550 nm wavelength light of the variable layer (active liquid crystal layer), d is the thickness of the liquid crystal layer (unit: μm), and T is the twist alignment mode of the Twist angle (in degrees).

The confirmation method of the twist direction and the twist angle of the twist orientation mode for confirming whether the above equation is satisfied is the same as described above.

When Equation 2 is satisfied, the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer with respect to light having a wavelength of 550 nm 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 is (0.16×Δnd×T/㎛ −8) or more, (0.16×Δnd×T/㎛-6) or more, and (0.16×Δnd×T/㎛) in another example. -4) or more, (0.16×Δnd×T/㎛-2) or more, (0.16×Δnd×T/㎛) or more, (0.16×Δnd×T/㎛+2) or more, (0.16×Δnd ×T/μm+4) or more or (0.16×Δnd×T/μm+6) or more.

In addition, the angle A in Equation 2 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, ) or less, (0.16×Δnd×T/μm+12) or less, (0.16×Δnd×T/μm+10) or less, (0.16×Δnd×T/μm+8) or less, (0.16×Δnd ×T/㎛+6) or less, (0.16×Δnd×T/㎛+4) or less, (0.16×Δnd×T/㎛+2) or less, or (0.16×Δnd×T/㎛) 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, the smaller angle among the angles between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment layer or the alignment direction of the liquid crystal alignment layer In the twist alignment mode, the angle between the slow axis and the alignment direction measured along the twisting direction satisfies the following Equation 3, or the angle between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment film is the greater of An angle or an angle between the slow axis and the alignment direction measured along a direction opposite to 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(2Δn×d×f)

[Equation 4]

A = (132±5) + (17±5)×sin(2Δn×d×f)

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

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

The confirmation method of the twist direction and the twist angle of the twist orientation mode for confirming whether the above equation is satisfied is the same as described above.

When Equation 3 or 4 is satisfied, the twist angle is 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. can

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

When Equation 1 is satisfied, the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer with respect to light having a wavelength of 550 nm and the thickness (d) of the liquid crystal layer can be in the 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 It may be about 1 μm or less or 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(2Δn×d×f), (42±1) + (17±1)×sin(2Δn×d) ×f) or (42 + 17 × sin(2Δn × d × f)), and the angle A in Equation 4 is (132±4) + (17±4) × sin(2Δn) in another example ×d×f), (132±3) + (17±3)×sin(2Δn×d×f), (132±2) + (17±2)×sin(2Δn×d×f) ), (132±1) + (17±1)×sin(2Δn×d×f) or (132+17×sin(2Δn×d×f)).

By disposing the retardation film having the above-described large optical anisotropy in the above positional relationship, it may be possible to provide a device having excellent transmittance variable characteristics and without a rainbow phenomenon, a mirroring phenomenon, and a crosstalk phenomenon.

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

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

For example, basically, the transmittance variable layer, particularly the 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 used as the retardation film described above. It can also be formed as (1st method).

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

3 is an example of implementing a device according to the first method, and such a device is the retardation film 100 , the electrode layer 400 , the alignment layer 300 , the active liquid crystal layer 200 , and the alignment layer arranged in sequence. 500 , an electrode layer 400 , and a substrate 600 may be included.

In addition, FIG. 4 is an example of implementing a device according to the second method, and such a device includes the phase difference film 100 , the substrate 600 , the electrode layer 400 , the alignment layer 300 , and the active liquid crystal arranged in sequence. It may include a layer 200 , an alignment layer 500 , an electrode layer 400 , and a substrate 600 .

That is, when implementing the device in the first manner, the retardation film is applied as a substrate, the liquid crystal alignment film described above may be formed on the surface of the retardation film, and when implementing the device in the second manner, the device is the liquid crystal The alignment layer may further include a substrate formed on its surface, and the retardation film may be attached to a surface of the substrate on which the liquid crystal alignment layer 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 a known transparent electrode layer may be applied as the electrode layer. 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 the transparent electrode layer are known and can be applied without limitation.

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

The type of 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, as the substrate, an inorganic film such as a glass film, a crystalline or amorphous silicon film, a quartz or an indium tin oxide (ITO) film, or a plastic film may be used. Examples of the plastic substrate include triacetyl cellulose (TAC); COP (cyclo olefin copolymer) 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); It is not limited.

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

For example, although not shown in the drawings, a spacer or sealant for maintaining an interval between the substrates may be included in addition to a known configuration, for example, the above-described substrate, a transmittance variable layer, and the like.

In addition, as other components, a pressure-sensitive adhesive or adhesive, a hard coating layer, an anti-reflection layer, a layer containing a dye having a NIR (Near-Infrared) cut function applied for use or other uses for attaching the retardation film to a substrate, etc. Known It may further include a configuration. In addition, if necessary, the device may or may not include a so-called passive polarization layer, for example, a passive polarization layer such as a poly(vinyl alcohol) (PVA)-based polarization layer.

The transmittance variable device as described above can be applied to various uses. For uses to which the transmittance variable device can be applied, an opening in a closed space including a building, container, or vehicle, such as a window or a sunroof, or for eyewear or windows, a light blocking plate of an organic light emitting device (OLED) and the like can be exemplified. In the above range of eyewear, general eyewear, sunglasses, sports goggles or helmets, or wearable devices such as virtual reality or augmented reality experience devices, etc. All eyewear formed so that an observer can observe the outside through a lens. can

A typical use to which the transmittance variable device of the present application can be applied is eyewear. Recently, sunglasses, sports goggles, or augmented reality experience devices have been marketed as eyewear in which a lens is mounted so as to be inclined from the observer's frontal line of sight. The transmittance variable device of the present application may be effectively applied to the aforementioned eyewear.

When the transmittance variable 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 lens for a left eye and a lens for a right eye; and a frame supporting the left eye lens and the right eye lens.

5 is an exemplary schematic diagram of the eyewear, which is a schematic diagram of the eyewear including the frame 82 and the lenses 84 for left and right eyes, but 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 lens for the left eye and the lens for the right eye may each include the transmittance variable device. Such a lens may include only the transmittance variable 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 the present application, it is possible to provide a variable transmittance device that has excellent transmittance variable characteristics and does not cause problems such as crosstalk, rainbow, or mirroring, which can be applied to various purposes. .

1 to 4 are schematic diagrams of an exemplary transmittance variable device of the present application.
5 exemplarily shows eyewear.
6 is a schematic view for explaining a method of 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 transmittance variable film.
8 is a view showing a method for evaluating refractive index anisotropy.
9 to 12 are diagrams showing the results of Examples or Comparative Examples.

Hereinafter, the present application will be described in detail through Examples, but the scope of the present application is not limited by the Examples below.

1. Evaluation of retardation of polymer films

The in-plane retardation value (Rin) of the polymer film was measured for light having a wavelength of 550 nm using Agilent's UV/VIS spectroscope 8453 equipment. After installing two polarizers in a UV/VIS spectroscope so that their transmission axes are orthogonal to each other, the slow axis of the polymer film forms 45 degrees with the transmission axes of the two polarizers, respectively, between the two polarizers, transmittance according to wavelength was measured. A phase retardation order of each peak is obtained from the transmittance graph according to wavelength. Specifically, in the transmittance graph according to wavelength, the waveform satisfies the following Equation A, and the maximum peak (Tmax) condition in the sine waveform satisfies the following Equation B. In the case of λmax in Equation A, since T of Equation A and T of Equation B are the same, the expression is expanded. Expanding the equations for n+1, n+2, and n+3, arranging the n and n+1 equations to eliminate R, and rearranging n into the λn and λn+1 equations, the following equation C is derived. Since T in Equation A and T in Equation B are the same, n and λ can be known, so R is obtained for each of λn, λn+1, λn+2 and λn+3. Obtain a straight line trend line of R value according to wavelength for 4 points and calculate R value for Equation 550 nm. The function of a straight trend line is Y=ax+b, where a and b are constants. The Y value when 550 nm is substituted for x of the above function is the 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 the in-plane phase difference (Rin), λ means the wavelength, and n means the vertex order of the sine wave.

2. Thickness evaluation of the transmittance variable layer (liquid crystal layer)

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

[Formula E]

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

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

After that, as shown in FIG. 8, when a linear polarizing plate is applied to the eyepiece side and light is irradiated and observed, θe and θo as shown in FIG. 8 can be obtained, and the refractive index of the measuring prism (n _p ) and the angles (θe and θo), the abnormal 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 index 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 fabricated using Toyobo's high-stretch PET (Polyethylene terephthalate) film substrate (SRF substrate, thickness: 80㎛, manufacturer: Toyobo, product name: TA044). First, an indium tin oxide (ITO) film (electrode layer) was deposited on one surface of the SRF substrate, and an alignment film was formed. The applied SRF substrate has an in-plane retardation of approximately 11,000 nm to 14,000 nm based on a wavelength of 550 nm after the ITO film is deposited. As the alignment layer, a polyimide-based horizontal alignment layer (SE-7492, Nissan) with a thickness of approximately 300 nm was formed by rubbing with a rubbing cap, and the rubbing direction (orientation direction) and the slow axis direction of the SRF substrate were approximately 12 clockwise. (Preparation of upper substrate and viewer-side substrate). In the same manner, a lower substrate was prepared. The upper substrate and the lower substrate were arranged so that each alignment layer was opposite to each other (cell gap: 6 μm), and a liquid crystal material was injected therein and then sealed to fabricate a device.

At the time of the arrangement, the orientation directions of the lower substrates 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) containing a liquid crystal compound having a positive dielectric anisotropy with a refractive index anisotropy (Δn) of 0.13 and a dichroic dye A composition was used in which the concentration was about 0.38% by weight. The obtained transmittance variable 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) measured according to the twisting direction of the twist mode and the liquid crystal alignment layer The angle formed by the orientation direction is approximately 12 degrees.

Comparative Example 1.

As a polymer film substrate, a PC (Polycarbonate) film substrate (PC substrate, thickness: 100㎛, 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 Examples and Comparative Examples, an absorption-type linear poly(vinyl alcohol) polarizer is disposed on the upper SRF substrate or PC substrate surface of the device manufactured, respectively, and the light is emitted while rotating the absorption axis of the polarizer in the range of 0 degrees to 360 degrees. The change in color coordinates (CIE La*b*) of the light was measured. 9 is a comparison view 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. From the drawings, it can be seen that the change in color coordinates (a*-b* color coordinate) of Example 1 is significantly smaller in the case of Example 1 than in the case of Comparative Example 1.

Example 2.

10 is a GHLC mixture (MDA-16) comprising a liquid crystal compound having a positive dielectric anisotropy with a refractive index anisotropy (Δn) of 0.13 and a dichroic dye as a liquid crystal material, except that a device is fabricated in the same manner as in Example 1; -1235, Merck) using a liquid crystal material in which a chiral dopant (S811, Merck) is mixed, and the thickness of the liquid crystal layer, that is, the cell gap is 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 minimum color coordinate change when the color coordinate change is measured at the twist angle (T) in the same manner as in Test Example 1. 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. can be controlled by controlling In addition, the twist angle (X-axis) is controllable through the amount of the chiral dopant added. The vertical scatter bar shown in the figure shows the optimal slow axis angle. From the drawings, it can be seen that when the twist angle is 180 degrees or less, the optimum angle follows Equation 1 below.

[Formula 1]

0.16×Δnd×T/㎛ - 10 ≤ A ≤ 0.16 ×Δnd×T/㎛ + 20

In Equation 1, Δn is the refractive index anisotropy of the liquid crystal layer with respect to light of a wavelength of 550 nm, in Example 2, 0.13, and d is the thickness (unit: μm) of the liquid crystal layer, in Example 2, 6 μm, and T is the twist angle (unit: degrees) of the twist orientation mode.

Example 3.

11 is a GHLC mixture (SHN-5011XX) comprising a dichroic dye and a liquid crystal compound having a positive dielectric anisotropy having a refractive index anisotropy (Δn) of 0.076 as a liquid crystal material, except that a device was fabricated in the same manner as in Example 1; A mixture of LG Chem's dichroic dye (JD 12, a dye mixed with three types of dyes of cyan, magenta, and yellow color in UK color systhesis solution) as a dichroic dye to (JNC) at a concentration of approximately 1.8% by weight ) using a liquid crystal material containing a chiral dopant (S811, Merck), and the thickness of the liquid crystal layer, that is, the cell gap is 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 minimum color coordinate change when the color coordinate change is measured at the twist angle (T) in the same manner as in Test Example 1. 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. can be controlled by controlling In addition, the twist angle (X-axis) is controllable through the amount of the chiral dopant added. The vertical scatter bar shown in the figure shows the optimal slow axis angle. From the figure, it can be seen that the optimum angle conforms to 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 dichroic dye and a liquid crystal compound having a positive dielectric anisotropy having a refractive index anisotropy (Δn) of 0.076 as a liquid crystal material, except that a device was fabricated in the same manner as in Example 1; A mixture of LG Chem's dichroic dye (JD 12, a dye mixed with three types of dyes of cyan, magenta, and yellow color in UK color systhesis solution) as a dichroic dye to (JNC) at a concentration of approximately 1.8% by weight ) is a diagram showing the results when a liquid crystal material containing a chiral dopant (S811, Merck) is used and the thickness of the liquid crystal layer, that is, a cell gap, is 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 minimum color coordinate change when the color coordinate change is measured at the twist angle (T) in the same manner as in Test Example 1. 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. can be controlled by controlling In addition, the twist angle (X-axis) is controllable through the amount of the chiral dopant added. The vertical scatter bar shown in the figure shows the optimal slow axis angle. From the figure, it can be seen that the optimum angle conforms to 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 4,000 nm or more with respect to light having a wavelength of 550 nm; liquid crystal alignment film; and a liquid crystal layer comprising a dichroic dye, which can implement a twisted alignment mode, in order,
without a passive polarization layer,
The twist angle of the twist orientation mode is in the range of 50 degrees to 180 degrees,
The product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer with respect to light of a wavelength of 550 nm and the thickness (d) of the liquid crystal layer exceeds 0.7 μm,
A transmittance variable device in which a small angle A among the angles between the slow axis of the retardation film and the alignment direction of the liquid crystal aligning film satisfies Equation 1:
[Formula 1]
0.16×Δnd×T/㎛ - 10 ≤ A ≤ 0.16 ×Δnd×T/㎛ + 20
In Equation 1, Δn is the refractive index anisotropy of the liquid crystal layer with respect to 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: degrees) to be. The transmittance variable device according to claim 1, wherein the transmittance variable device is capable of switching between a transmissive mode state and a blocking mode state, wherein the maximum transmittance (Tmax) in the transmissive mode state and the minimum transmittance (Tmin) in the interrupted mode state are The transmittance variable device, wherein the ratio (Tmax/Tmin) is in the 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 twisted alignment mode in the alignment direction of the liquid crystal aligning film. 4. The 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 aligning film is formed on a surface of the retardation film. According to claim 1, wherein the transmittance variable device further comprises a substrate, the liquid crystal aligning film is formed on the surface of the substrate, the retardation film is attached to the surface of the substrate on which the liquid crystal aligning film is not formed Transmittance variable device. The device according to claim 1, wherein the twist orientation mode is a horizontal twist orientation mode or an oblique twist orientation mode. delete The transmittance variable device according to claim 1, wherein the liquid crystal layer contains a chiral agent. The transmittance variable device according to claim 1, wherein the liquid crystal layer has a thickness of 20 mu m or less. left and right eye lenses; and a frame supporting the left eye lens and the right eye lens,
The eyewear for each of the left eye lens and the right eye lens includes the transmittance variable device of claim 1.

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