KR102230818B1 - Method for manufacturing optical device - Google Patents

Abstract

The present application provides a method of manufacturing an optical device capable of preventing wrinkles from occurring in the bonding process.

Description

TECHNICAL FIELD [Method for manufacturing optical device]

The present application relates to a method of manufacturing an optical device.

The sunroof generally refers to a fixed or movable (venting or sliding) opening in the ceiling of a vehicle, and functions to allow light or fresh air to flow into the interior of the vehicle.

The sunroof may be installed in a vehicle using, for example, a laminate in which an optical element layer having a predetermined visible light transmittance or a variable visible light transmittance is inserted between a translucent substrate layer such as glass. In the present application, the term visible light may mean light having a wavelength in the range of about 400 nm to 700 nm. In the present application, the term visible light transmittance may be a transmittance for any one wavelength corresponding to the visible light, or may mean an average of transmittance for all light in the visible light region. In the above example, in order to insert the optical element layer between the light-transmitting substrate layer, a hot-melt adhesive is disposed between the light-transmitting substrate layer and the optical element layer, and heat is applied to insert the optical element layer between the light-transmitting substrate layer. The device can be manufactured.

However, in the process of bonding by applying heat, wrinkles are generated at the interface between the adhesive and the light-transmitting substrate layer due to the difference in temperature uniformity of the laminate, resulting in a poor aesthetic appearance.

The present application provides a method of manufacturing an optical device.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. The accompanying drawings show exemplary embodiments of the present invention, which are provided to aid in understanding the present invention. In the accompanying drawings, the thickness may be enlarged to clearly express each layer and region, and the scope of the present invention is not limited by the thickness, size, and ratio indicated in the drawings.

The present application relates to a method of manufacturing an optical device. 1 is a diagram showing a laminate of an exemplary method for manufacturing an optical device of the present application. As shown in FIG. 1, the laminate has a first light-transmitting substrate layer 160, a first adhesive layer 150, an optical element layer 142, a second adhesive layer 130, and a second translucent layer stacked in sequence. And attaching the laminate by applying pressure in the thickness direction of the laminate while applying heat to the laminate including the base layer 120. By applying heat to the laminated body as described above, an optical device including an optical element layer encapsulated by an adhesive layer between the first and second translucent base layers disposed opposite to each other can be manufactured.

In the present application, the term light transmittance may refer to a straight light transmittance of about 60% or more, about 70% or more, about 80% or more, or about 80% or more for visible light. The transmittance may be a straight light transmittance. In the present application, the term straight light transmittance may be a ratio of light (straight light) transmitted through the object in the same direction as the incident direction to light incident on an object in a predetermined direction. In one example, the transmittance may be a measurement result (normal light transmittance) of light incident in a direction parallel to the surface normal of the translucent base layer.

In the bonding process, a process base layer having a higher thermal conductivity than the light-transmitting base layer may be disposed outside at least one of the first and second light-transmitting base layers. For example, as shown in FIG. 1, a process base layer 170 having a higher thermal conductivity than the first light-transmitting base layer 160 may be disposed outside the first light-transmitting base layer 160. In the present application, the term outside of the light-transmitting base layer may mean a position other than between the first and second light-transmitting base layers constituting the laminate, and preferably, adjacent to the optical element layer of the first or second light-transmitting base layer. It may mean that it is located on the opposite side of the side. Referring to FIG. 1, the optical element layer of the first light-transmitting base layer 160, wherein the process base layer 170 is a position other than between the first light-transmitting base layer 160 and the second light-transmitting base layer 120 ( Since it is located on the side opposite to the surface adjacent to 142, the process base layer 170 may be said to be located outside the first light-transmitting base layer 160. In FIG. 1, the process base layer 170 positioned outside the first light-transmitting base layer 160 is in contact with the first light-transmitting base layer 160, but the first light-transmitting base layer 110 and the process base layer 170 are in contact with each other. Other layers not shown in FIG. 1 may be positioned between them.

The manufacturing method of the optical device of the present application is by applying heat after disposing the process substrate layer having the above thermal conductivity on the outside of at least one of the first and second translucent substrate layers, while the heat is applied. By reducing the temperature deviation according to the position of the adhesive layer as possible, it is possible to prevent wrinkles from occurring due to temperature unevenness during the bonding process.

The process base layer may be disposed outside at least one of the first and second light-transmitting base layers, and is preferably located outside of both the first and second light-transmitting base layers and may occur during the bonding process. It can maximize wrinkle suppression power.

Since the process base layers 110 and 170 of the laminate have better thermal conductivity than the first and second translucent base layers 120 and 160 to prevent wrinkles that may occur during the bonding process, the thermal conductivity value is the first. And 2 should be larger than the translucent base layer. The thermal conductivity of the process base layer may be, for example, a lower limit of 5W/mK or more or 10W/mK or more. When the lower limit of the thermal conductivity satisfies the above range, wrinkles that may occur during the bonding process can be effectively prevented. The upper limit of the thermal conductivity of the process base layer is not particularly limited because the higher the thermal conductivity value, the better the ability to prevent wrinkles in the bonding process, but may be, for example, 700W/mK or less or 500W/mK or less. In the case where the value of the physical property values used in the present specification changes according to temperature and/or pressure, the physical property values used may be values at room temperature and pressure, unless otherwise specified.

The term room temperature is a natural temperature that is not heated or reduced, and may generally be any temperature within the range of about 10°C to 30°C, about 23°C, or about 25°C.

The term atmospheric pressure is a natural pressure that is not specifically reduced or increased, and generally refers to a pressure of about 1 atmosphere, such as atmospheric pressure.

The type of the process base layer of the present application is not particularly limited as long as it satisfies the above-described conditions. The type of the process base layer may be, for example, a stainless steel base layer, an aluminum base layer, a tungsten base layer, an iron base layer, a cast iron base layer, a carbon steel base layer, a copper base layer, a bronze base layer, or a lead base layer.

As the process substrate layer, for example, a stainless steel substrate layer may be used. The stainless steel may be an austenitic stainless steel, a ferritic stainless steel, a martensitic stainless steel, a precipitation hardening martensitic stainless steel, or a duplex stainless steel.

As the process substrate layer, preferably, an aluminum substrate layer can be used. Since aluminum has excellent thermal conductivity, it can effectively prevent wrinkles that may occur during bonding, and has the advantage of being easy to cut because it is easy to cold plastic processing and cutting processing.

The thickness of the process substrate layer of the present application may be determined in consideration of the thickness of the light-transmitting substrate layer, the adhesive layer, and the optical element layer included in the laminate, the conditions of the step of applying heat, and the method of applying heat, and is not particularly limited. . The thickness of the process base layer may be in the range of, for example, 0.5mm to 50mm, 1mm to 25mm, or 3mm to 8mm.

The type of the first and second light-transmitting base layers of the present application is not particularly limited as long as they satisfy the light-transmitting properties described above. The first and second light-transmitting substrate layers may each independently be a soda-lime glass layer, a lead glass layer, a soda alumina glass layer, an alkali borosilicate glass layer, or a borosilicate alumina glass layer.

The thickness of the first and second translucent base layers of the present application may be determined in consideration of the use of the laminated body, and is not particularly limited. The thickness of the first and second translucent substrate layers may be, for example, 1 mm to 10 mm.

The first and second adhesive layers of the present application may be hot melt adhesive layers. The hot-melt adhesive may refer to, for example, an adhesive that is solid at room temperature and solidifies while melting and cooling when heat is applied to exert adhesive strength. In the manufacturing method of the optical device of the present application, in order to insert the optical element layer between the transparent substrate layer, a thermoplastic adhesive layer, which is a hot-melt adhesive layer, is disposed between the transparent substrate layer and the optical element layer, and the laminate is bonded by applying heat. By doing so, it is possible to manufacture an optical device including an optical element layer encapsulated by an adhesive layer.

The type of the first and second adhesive layers is not particularly limited as long as heat is applied to bond the first and second light-transmitting substrate layers and the optical element layer, and encapsulate the optical element layer. The first and second adhesive layers may each independently be a thermoplastic polyurethane adhesive layer, a thermoplastic polyamide adhesive layer, a thermoplastic polyester adhesive layer, a thermoplastic polyolefin adhesive layer, or an ethylene vinyl acetate adhesive layer.

The first and second adhesive layers may be preferably thermoplastic polyurethane adhesive layers (TPU: thermoplastic polyurethane). When using a thermoplastic polyurethane, it is possible to provide a laminate having excellent durability by bonding.

The thickness of the first and second adhesive layers may be determined according to the use of the laminate manufactured by bonding, and is not particularly limited. The thickness of the first and second adhesive layers may be, for example, in the range of 100 μm to 900 μm, 100 μm to 800 μm, or 300 μm to 500 μm.

The method of manufacturing an optical device of the present application may be a method of manufacturing an optical device in which the optical element layer is encapsulated with an adhesive layer surrounding the upper surface, the lower surface, and the side surface of the optical element layer. For example, since the first and second adhesive layers may be formed using a hot-melt adhesive, heat is applied to the laminate to be laminated on the upper and lower portions of the optical element layer in the process of melting-cooling the hot-melt adhesive. The first and second adhesive layers may be encapsulated so as to surround the side surfaces of the optical element layer.

In another example, in order to manufacture an optical device in which the upper, lower and side surfaces of the optical element layer are encapsulated with an adhesive layer, the laminate to which heat is applied adds a third adhesive layer disposed on the side of the optical element layer. Can be included as. Referring to FIG. 1, the exemplary laminate of the present application may further include a third adhesive layer 140 disposed on a side surface of the optical element layer 142. Since the laminate includes the third adhesive layer disposed on the side of the optical element layer, when heat is applied to the laminate, the adhesive layer can be removed from the side of the optical element layer by melting and cooling the third adhesive layer disposed on the side. While encapsulating, an adhesive layer and/or a light-transmitting substrate layer positioned above and below the optical device layer may be bonded.

Matters regarding the material and thickness constituting the third adhesive layer are the same as those described in the first and second adhesive layers, and thus will be omitted.

The type of the optical element layer of the present application is not particularly limited as long as it has a property capable of imparting optical properties according to the use of the laminated body. The optical element layer of the present application may be, for example, an optical element layer having a variable visible light transmittance or blocking part of the incident visible light so that the manufactured optical device can be used for a sunroof.

The optical element layer may be, for example, an optical element capable of switching between a transmission mode and a blocking mode. The transmission mode may mean a state of an optical element such that the visible light transmittance of the optical device is about 30% or more, about 35% or more, about 40% or more, or about 50% or more. The blocking mode may mean a state of an optical element such that the visible light transmittance of the optical device is about 20% or less, about 15% or less, or about 10% or less. The transmittance may be the above-described straight light transmittance. The optical element is also a mode other than the above-described transmission mode and blocking mode, e.g., a mode representing an arbitrary transmittance between the transmittance of the transmission and blocking mode, or the transmittance of the transmittance to the naked eye while the transmittance varies depending on the position. It can be designed to implement a mode in which a gradation is observed.

Such switching between modes can be achieved by the optical device comprising an active liquid crystal element. In the above, the active liquid crystal element is a liquid crystal element capable of switching between alignment states of at least two or more optical axes, for example, first and second alignment states. In the above, the optical axis may mean the direction of the long axis of the liquid crystal compound included in the liquid crystal device in a rod-type shape, and in the case of a discotic shape, it may mean a normal direction of the plane of the disk. For example, when a liquid crystal device includes a plurality of liquid crystal compounds whose optical axes have different directions in a certain alignment state, the optical axis of the liquid crystal device may be defined as an average optical axis, and in this case, the average optical axis is the optical axis of the liquid crystal compounds. It can mean a vector sum.

In the liquid crystal device as described above, the alignment state can be changed by application of energy, for example, application of voltage. For example, the liquid crystal device may have one of the first and second alignment states in a state in which no voltage is applied, and then switch to another alignment state when a voltage is applied.

The blocking mode may be implemented in one of the first and second alignment states, and the transmission mode may be implemented in another alignment state. For convenience, in this specification, it is described that the blocking mode is implemented in the first state.

The liquid crystal device may include a liquid crystal layer including at least a liquid crystal compound. In one example, the liquid crystal layer is a so-called guest host liquid crystal layer, and may be a liquid crystal layer including a liquid crystal compound and an anisotropic dye.

The liquid crystal layer is a liquid crystal layer using a so-called guest host effect, and is a liquid crystal layer in which the anisotropic dye is aligned according to an alignment direction of the liquid crystal compound (hereinafter, it may be referred to as a liquid crystal host). The orientation direction of the liquid crystal host may be adjusted according to whether or not the above-described external energy is applied.

The type of liquid crystal host used in the liquid crystal layer is not particularly limited, and a general type of liquid crystal compound applied to implement a guest host effect may be used.

For example, as the liquid crystal host, a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound may be used. In general, a nematic liquid crystal compound may be used. The term nematic liquid crystal compound refers to a liquid crystal compound that can be arranged in an orderly manner in the direction of the molecular axis, although there is no regularity on the position of liquid crystal molecules, and such liquid crystal compounds are in the form of a rod or a disc (discotic). Can be

Such nematic liquid crystal compounds are, for example, about 40°C or more, about 50°C or more, about 60°C or more, about 70°C or more, about 80°C or more, about 90°C or more, about 100°C or more, or about 110°C or more. It may be selected to have a clearing point or to have a phase transition point in the above range, that is, a phase transition point from a nematic phase to an isotropic phase. In one example, the clearing point or the phase transition point may be about 160°C or less, about 150°C or less, or about 140°C or less.

The liquid crystal compound may have a negative or positive dielectric anisotropy. The absolute value of the dielectric anisotropy may be appropriately selected in consideration of the purpose. For example, the dielectric anisotropy may be greater than 3 or greater than 7, less than -2 or less than -3.

The liquid crystal compound may also have an optical anisotropy (Δn) of about 0.01 or greater or about 0.04 or greater. The optical anisotropy of the liquid crystal compound may be about 0.3 or less or about 0.27 or less in other examples.

Liquid crystal compounds that can be used as the liquid crystal host of the guest host liquid crystal layer are known to experts in the art, and can be freely selected from them.

The liquid crystal layer includes an anisotropic dye together with the liquid crystal host. The term dye may refer to a material capable of intensively absorbing and/or modifying light in at least a part or the entire range in the visible light region, for example, 380 nm to 780 nm wavelength range, and the term anisotropic dye is the It may mean a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region.

As the anisotropic dye, for example, a known dye known to have a property that can be aligned according to the alignment state of the liquid crystal host may be selected and used. For example, an azo dye or an anthraquinone dye may be used as the anisotropic dye, and the liquid crystal layer may contain one or two or more dyes in order to achieve light absorption in a wide wavelength range.

The dichroic ratio of the anisotropic dye may be appropriately selected in consideration of the purpose. For example, the anisotropic dye may have a dichroic ratio of 5 to 20 or less. The term dichroic ratio, for example, in the case of a p-type dye, may mean a value obtained by dividing the absorption of polarized light parallel to the major axis direction of the dye by the absorption of polarized light parallel to the direction perpendicular to the major axis direction. The anisotropic dye may have the dichroic ratio in at least a portion of the wavelength or in any one or the entire range in the wavelength range of the visible light region, for example, in the wavelength range of about 380 nm to 780 nm or about 400 nm to 700 nm. have.

The content of the anisotropic dye in the liquid crystal layer may be appropriately selected in consideration of the purpose. For example, the content of the anisotropic dye may be selected within the range of 0.1 to 10% by weight based on the total weight of the liquid crystal host and the anisotropic dye. The ratio of the anisotropic dye can be changed in consideration of the desired transmittance and the solubility of the anisotropic dye in the liquid crystal host.

The liquid crystal layer basically includes the liquid crystal host and an anisotropic dye, and if necessary, may further include other optional additives according to known forms. As an example of the additive, a chiral dopant or a stabilizer may be exemplified, but is not limited thereto.

The liquid crystal layer may have an anisotropy (R) of about 0.5 or more. The anisotropy (R) is the absorbance of light polarized parallel to the alignment direction of the liquid crystal host (E(p)) and the absorbance of light polarized perpendicular to the alignment direction of the liquid crystal host (E(s)). It is measured according to the following equation.

<Anisotropy formula>

Anisotropy (R) = [E(p)-E(s)] / [E(p) + 2*E(s)].

The criterion used above is another identical device that does not contain a dye in the liquid crystal layer.

Specifically, the anisotropy (R) is from the value for the absorbance of the liquid crystal layer in which the dye molecules are horizontally oriented (E(p)) and the value for the absorbance of the same liquid crystal layer in which the dye molecules are vertically oriented (E(s)). Can be measured. The absorbance is measured by comparing it with a liquid crystal layer that does not contain any dye but has the same configuration elsewhere. These measurements are performed using a polarized light beam that vibrates in a direction parallel to the orientation direction (E(p)) in the case of one vibrating surface, and vibrates in a direction perpendicular to the orientation direction (E(s)) in subsequent measurements. Can be. The liquid crystal layer is not switched or rotated during the measurement, and therefore, the measurement of E(p) and E(s) can be performed by rotating the vibrating surface of the polarized incident light.

An example of a detailed procedure is as described below. Spectra for measurement of E(p) and E(s) can be recorded using a spectrometer such as a Perkin Elmer Lambda 1050 UV spectrometer. The spectrometer is equipped with a Glan-Thompson polariser for a wavelength range of 250 nm to 2500 nm in both the measuring beam and the reference beam. The two polarizers are controlled by a stepping motor and are oriented in the same direction. The change in the polarizer direction of the polarizer, for example, switching from 0 degrees to 90 degrees is always performed synchronously and in the same direction with respect to the measurement beam and the reference beam. The orientation of the individual polarizers was determined by the University of Wurzburg's T. It can be measured using the method described in T. Karstens' 1973 dissertation.

In this method, the polarizer is rotated in steps of 5 degrees with respect to the oriented dichroic sample, and the absorbance is recorded at a fixed wavelength, for example in the region of maximum absorption. A new reference line zero line is executed for each polarizer position. For the measurement of the two dichroic spectra E(p) and E(s), an antiparallel-rubbed test cell coated with polyimide AL-1054 from JSR was placed in both the measuring beam and the reference beam. The two test cells can be selected with the same layer thickness. The test cell containing the pure host (liquid crystal compound) is placed in the reference beam. A test cell containing a solution of dye in the liquid crystal is placed in the measuring beam. Two test cells for the measuring beam and the reference beam are installed in the ray path in the same orientation direction. In order to ensure the maximum possible precision of the spectrometer, E(p) may necessarily be within its maximum absorption wavelength range, for example in the range of 0.5 to 1.5. This corresponds to a transmittance of 30% to 5%. This is set by adjusting the layer thickness and/or dye concentration accordingly.

The anisotropy (R) is determined by E(p) and E(s) according to the above equations as shown in the literature ("Polarized Light in Optics and Spectroscopy", DS Kliger et al., Academic Press, 1990). Can be calculated from the measured values for

The anisotropy (R) may be about 0.55 or more, 0.6 or more, or 0.65 or more in another example. The anisotropy (R) may be, for example, about 0.9 or less, about 0.85 or less, about 0.8 or less, about 0.75 or less, or about 0.7 or less.

Such anisotropy (R) can be achieved by controlling the type of the liquid crystal layer, for example, the type of the liquid crystal compound (host), the type and ratio of the anisotropic dye, the thickness of the liquid crystal layer, and the like.

Although lower energy is used through the anisotropy R within the above range, it is possible to provide an optical device in which the contrast ratio is increased because the difference between the transmittance in the transmission state and the blocking state increases.

The thickness of the liquid crystal layer may be appropriately selected in consideration of a purpose, for example, a desired degree of anisotropy. In one example, the thickness of the liquid crystal layer is about 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, 3.5 μm or more, 4 μm or more , 4.5 μm or more, 5 μm or more, 5.5 μm or more, 6 μm or more, 6.5 μm or more, 7 μm or more, 7.5 μm or more, 8 μm or more, 8.5 μm or more, 9 μm or more, or 9.5 μm or more. By controlling the thickness in this way, an optical device having a large difference between the transmittance in the transmission state and the transmittance in the blocking state, that is, a device having a large contrast ratio can be implemented. The thicker the thickness, the higher the contrast ratio can be implemented, and thus is not particularly limited, but may generally be about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

The active liquid crystal layer as described above or a liquid crystal device including the same may switch between a first alignment state and a second alignment state different from the first alignment state. The switching may be controlled through application of external energy such as voltage. For example, one of the first and second alignment states may be maintained in a voltage unapplied state, and then may be switched to another alignment state by applying a voltage.

The first and second orientation states may be selected from a horizontal orientation, a vertical orientation, a twist nematic orientation, or a cholesteric orientation, respectively, in an example. For example, in the blocking mode, the liquid crystal element or the liquid crystal layer is at least horizontal alignment, twist nematic alignment, or cholesteric alignment, and in the transmission mode, the liquid crystal element or liquid crystal layer is different from the vertical alignment or the horizontal alignment of the blocking mode. It may be in a horizontal orientation state with an optical axis in a different direction. The liquid crystal device may be a device in a normally black mode in which the cut-off mode is implemented in a state where no voltage is applied, or may implement a normal transparent mode in which the transmission mode is implemented in a state in which a voltage is not applied.

In the alignment state of the liquid crystal layer, a method of determining in which direction the optical axis of the liquid crystal layer is formed is known. For example, the direction of the optical axis of the liquid crystal layer can be measured using another polarizing plate that knows the direction of the optical axis, which can be measured using a known measuring device, for example, a polarimeter such as Jascp's P-2000. I can.

A method of implementing a liquid crystal element in a normal transmission or blocking mode as described above by controlling dielectric anisotropy of a liquid crystal host and an alignment direction of an alignment layer for aligning the liquid crystal host is known.

The liquid crystal device may include two base films disposed opposite to each other and the active liquid crystal layer present between the two base films.

In addition, in the liquid crystal element, a spacer for maintaining a gap between the two base films and/or a gap between the two base films arranged opposite to each other is maintained between the two base films, and the base film is attached thereto. It may further include a sealant. As the spacer and/or sealant, a known material may be used without particular limitation.

As the base film, for example, an inorganic film or a plastic film made of glass or the like can be used. As a plastic film, TAC (triacetyl cellulose) film; COP (cycloolefin copolymer) films such as norbornene derivatives; Acrylic film, such as PMMA (poly(methyl methacrylate)); PC (polycarbonate) film; PE (polyethylene) film; PP (polypropylene) film; PVA (polyvinyl alcohol) film; DAC (diacetyl cellulose) film; Pac (polyacrylate) film; PES (polyether sulfone) film; PEEK (polyetheretherketon) film; PPS (polyphenylsulfone) film, PEI (polyetherimide) film; PEN (polyethylenemaphthatlate) film; PET (polyethyleneterephtalate) film; PI (polyimide) film; PSF (polysulfone) film; A PAR (polyarylate) film or a fluororesin film may be used, but is not limited thereto. For the base film, a coating layer of a silicon compound such as gold, silver, silicon dioxide or silicon monoxide, or a coating layer such as an antireflection layer, if necessary May exist.

As the base film, a film having a retardation in a predetermined range may be used. In one example, the base film may have a front retardation of 100 nm or less. In another example, the front phase difference is about 95 nm or less, about 90 nm or less, about 85 nm or less, about 80 nm or less, about 75 nm or less, about 70 nm or less, about 65 nm or less, about 60 nm or less, about 55 nm or less, about 50 nm or less, about 45 nm or less , About 40 nm or less, about 35 nm or less, about 30 nm or less, about 25 nm or less, about 20 nm or less, about 15 nm or less, about 10 nm or less, about 5 nm or less, about 4 nm or less, about 3 nm or less, about 2 nm or less, about 1 nm or less Or about 0.5 nm or less. In another example, the front phase difference is about 0 nm or more, about 1 nm or more, about 2 nm or more, about 3 nm or more, about 4 nm or more, about 5 nm or more, about 6 nm or more, about 7 nm or more, about 8 nm or more, about 9 nm or more, or about 9.5 It may be greater than or equal to nm.

The absolute value of the retardation in the thickness direction of the base film may be, for example, 200 nm or less. In another example, the absolute value of the retardation in the thickness direction is 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 85 nm or less, 80 nm or less. , 70nm or less, 60nm or less, 50nm or less, 40nm or less, 30nm or less, 20nm or less, 10nm or less, 5nm or less, 4nm or less, 3nm or less, 2nm or less, 1nm or less or 0.5nm or less, 0nm or more, 10nm or more, 20nm It may be at least 30 nm, at least 40 nm, at least 50 nm, at least 60 nm, at least 70 nm, or at least 75 nm. If the absolute value of the retardation in the thickness direction is within the above range, the retardation in the thickness direction may be negative or positive, and may be, for example, a negative number.

In the present specification, the front retardation (Rin) is a value calculated by Equation 1 below, and the thickness direction retardation (Rth) is a value calculated by Equation 2 below, and unless otherwise specified, the reference wavelength of the front and thickness retardation Is about 550 nm.

[Equation 1]

Front phase difference (Rin) = d × (nx-ny)

[Equation 2]

Thickness direction retardation (Rth) = d × (nz-ny)

In Equations 1 and 2, d is the thickness of the base film, nx is the refractive index in the slow axis direction of the base film, ny is the refractive index in the fast axis direction of the base film, and nz is the refractive index in the thickness direction of the base film.

When the base film is optically anisotropic, the angle formed by the slow axes of the base films disposed oppositely is, for example, within a range of about -10 degrees to 10 degrees, within a range of -7 degrees to 7 degrees, and -5 degrees to 5 degrees. It may be in the range of degrees or in the range of -3 degrees to 3 degrees, or may be approximately parallel.

In addition, the angle formed by the slow axis of the base film and the light absorption axis of the polarizer to be described later is, for example, in the range of about -10 degrees to 10 degrees, in the range of -7 degrees to 7 degrees, and in the range of -5 degrees to 5 degrees. Within a range or within a range of -3 degrees to 3 degrees or may be approximately parallel, or within a range of about 80 degrees to 100 degrees, within a range of about 83 degrees to 97 degrees, within a range of about 85 degrees to 95 degrees, or from about 87 degrees It may be in the range of 92 degrees or approximately vertical.

Through the phase difference adjustment or the arrangement of the slow axis as described above, it may be possible to implement an optically excellent and uniform transmission and blocking mode.

The thickness of the base film as described above is not particularly limited, and may be, for example, in the range of about 50 μm to 200 μm.

In a liquid crystal device, a conductive layer and/or an alignment layer may be present on one surface of the base film, for example, on a surface facing the active liquid crystal layer.

The conductive layer present on the surface of the base film is a configuration for applying a voltage to the active liquid crystal layer, and a known conductive layer may be applied without particular limitation. As the conductive layer, for example, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide) may be applied. Examples of the conductive layer that can be applied in the present application are not limited to the above, and all types of conductive layers known to be applicable to liquid crystal devices in this field may be used.

In one example, an alignment layer is present on the surface of the base film. For example, a conductive layer may be first formed on one surface of the base film, and an alignment layer may be formed thereon.

The alignment layer is a configuration for controlling the alignment of a liquid crystal host included in the active liquid crystal layer, and a known alignment layer may be applied without particular limitation. Known alignment layers in the industry include rubbing alignment layers, photo alignment layers, and the like, and alignment layers that can be used in the present application are the known alignment layers, which are not particularly limited.

In order to achieve the above-described alignment of the optical axis, the alignment direction of the alignment layer may be controlled. For example, the orientation directions of the two alignment films formed on each side of the two base films disposed opposite to each other are within the range of about -10 degrees to 10 degrees, the angle within the range of -7 degrees to 7 degrees, and -5 degrees to It may be at an angle within the range of 5 degrees or an angle within the range of -3 degrees to 3 degrees, or may be approximately parallel to each other. In another example, the orientation directions of the two alignment layers are within a range of about 80 to 100 degrees, an angle within a range of about 83 to 97 degrees, an angle within a range of about 85 to 95 degrees, or within a range of about 87 to 92 degrees. They can be angled or approximately perpendicular to each other.

Since the direction of the optical axis of the active liquid crystal layer is determined according to the alignment direction, the alignment direction can be confirmed by checking the direction of the optical axis of the active liquid crystal layer.

The shape of the liquid crystal element having the above configuration is not particularly limited, and may be determined according to the application of the optical device, and is generally in the form of a film or a sheet.

The laminate may further include a polarizer together with the active liquid crystal device. The polarizer is disposed between the first and second translucent base layers. A laminate including a polarizer is, for example, as shown in FIG. 1, the first light-transmitting substrate layer 160, the first adhesive layer 150, the optical element layer 142, and the Including the second adhesive layer 130, the polarizer 141, the fourth adhesive layer 143 and the second light-transmitting base layer 120, the third disposed on the side of the optical element layer 142 It may include an adhesive layer 140. When bonding the laminated body as described above, an optical device in which the optical element layer and the polarizer are encapsulated by the adhesive layer can be manufactured. In the above example, since the laminate includes the fourth adhesive layer 143 between the optical element layer 142 and the polarizer 141, when heat is applied to the laminate, the optical element layer and the polarizer are formed by the fourth adhesive layer. Can be cemented. Matters regarding the thickness and type of the fourth adhesive layer are the same as those described for the first and second adhesive layers, and thus will be omitted.

As the polarizer, for example, an absorption type linear polarizer, that is, a polarizer having a light absorption axis formed in one direction and a light transmission axis formed substantially perpendicular thereto may be used.

When it is assumed that the blocking state is implemented in the first alignment state of the active liquid crystal layer, the polarizer has an angle formed by the average optical axis (a vector of the optical axis) of the first alignment state and the light absorption axis of the polarizer. It may be disposed in the optical device to be between 100 degrees or 85 degrees to 95 degrees, or to be approximately vertical, or to be between 35 degrees to 55 degrees or about 40 to 50 degrees, or to be disposed on the optical device to be approximately 45 degrees. have.

When the alignment direction of the alignment layer is taken as a reference, the alignment direction of the alignment layer formed on each side of the two base films of the two base films of the liquid crystal elements arranged opposite as described above is an angle within the range of about -10 degrees to 10 degrees to each other, -7 degrees to When an angle within the range of 7 degrees, an angle within the range of -5 degrees to 5 degrees, or an angle within the range of -3 degrees to 3 degrees, or substantially parallel to each other, the orientation direction of any one of the two alignment layers and the polarizer The angle formed by the light absorption axis may be 80 to 100 degrees or 85 to 95 degrees, or may be approximately vertical.

In another example, the orientation directions of the two alignment layers are within a range of about 80 degrees to 100 degrees, an angle within a range of about 83 degrees to 97 degrees, an angle within a range of about 85 degrees to 95 degrees, or within a range of about 87 degrees to 92 degrees. In the case of forming an angle or substantially perpendicular to each other, the angle formed by the alignment direction of the alignment layer disposed closer to the polarizer among the two alignment layers and the light absorption axis of the polarizer is 80 degrees to 100 degrees or 85 degrees to 95 degrees, or , Can be approximately vertical. For example, the liquid crystal element and the polarizer may be disposed so that the optical axis (average optical axis) in the first alignment direction of the liquid crystal element and the light absorption axis of the polarizer are in the above relationship while being stacked on each other.

In one example, when the polarizer is a polarization coating layer to be described later, a structure in which the polarization coating layer is inside the liquid crystal device may be implemented. For example, a structure in which the polarizing coating layer is present between any one of the base films of the liquid crystal device and the active liquid crystal layer may be implemented. For example, the above-described conductive layer, the polarizing coating layer, and the alignment layer may be sequentially formed on a base film.

The kind of the polarizer that can be applied in the optical device of the present application is not particularly limited. For example, as a polarizer, a common material used in conventional LCDs, for example, a PVA (poly(vinyl alcohol)) polarizer, a lyotropic liquid crystal (LLC), or a reactive liquid crystal (RM: A polarizer implemented by a coating method, such as a polarizing coating layer including reactive mesogen) and a dichroic dye, may be used. In the present specification, the polarizer implemented by the coating method as described above may be referred to as a polarization coating layer. As the lyotropic liquid crystal, a known liquid crystal may be used without any particular limitation, and for example, a lyotropic liquid crystal capable of forming a lyotropic liquid crystal layer having a dichroic ratio of about 30 to 40 may be used. Meanwhile, when the polarizing coating layer includes a reactive liquid crystal (RM) and a dichroic dye, a linear dye or a discotic dye may be used as the dichroic dye. May be.

The optical device of the present application may include only one of the active liquid crystal elements and polarizers as described above. Thus, the optical device may include only one of the active liquid crystal elements, and may include only one polarizer.

The manufacturing method of the optical device of the present application includes the step of bonding the laminate by applying pressure in the thickness direction of the laminate while applying heat to the laminate.

A method of applying heat to the laminate in the bonding process is not particularly limited, and a method known in the bonding field using a hot-melt adhesive may be used. For example, a method of placing the laminate in an autoclave chamber and raising the temperature may be used.

The step of applying the heat may sequentially include, for example, a heating step, a constant temperature step, and a temperature reduction step. In the present application, the temperature raising step refers to a step of raising the temperature outside the laminate, the constant temperature step refers to a step of maintaining a constant temperature outside the laminate, and the temperature reduction step lowers the temperature of the outer side of the laminate. It can mean the step of letting go. The temperature outside the laminate may mean, for example, a temperature of air existing outside the laminate. In one example, the step of applying heat may be performed using an autoclave. Specifically, heat can be applied to the laminate by placing the laminate in the chamber of the autoclave and changing the temperature of the chamber of the autoclave according to the above-described heating, constant temperature, and temperature reduction steps.

The time for raising the temperature in the heating step is not particularly limited, but may be performed for a time within the range of, for example, 10 minutes to 30 minutes. The heating step may be performed by increasing the temperature at a constant rate from room temperature to a predetermined temperature to be maintained in the constant temperature step for the above time.

The time for maintaining the constant temperature in the constant temperature step is not particularly limited, but may be performed for a time within the range of, for example, 10 minutes to 5 hours. In the constant temperature step, for example, during the time period, the temperature may be maintained at a temperature in the range of 70°C to 200°C, 80°C to 150°C, or 80°C to 120°C.

The bonding step may be performed under a pressure of 500 to 2,000 mmHg, 500 to 1,500 mmHg, or 500 to 1,000 mmHg. That the bonding step is performed under a predetermined pressure may mean the temperature of the environment in which the laminate is placed before applying pressure to the laminate. For example, after the laminate is put in a vacuum bag having a pressure of 750 mmHg, heat and pressure may be applied in an autoclave chamber.

The pressure applied to the laminate in the bonding step may be in the range of 1.5bar to 10bar, 1.5bar to 5bar, or 1.5bar to 3bar. When the pressure is applied to the laminate in the bonding step, for example, it may mean the pressure of the chamber raised while heat is applied to the laminate placed in the autoclave chamber under normal pressure conditions. The pressure applied to the laminate may be within the pressure range during the heating step, the constant temperature step, and the temperature reduction step, or within the pressure range during any one of the steps.

The manufacturing method of the optical device of the present application may provide an optical device further including any necessary configuration in addition to the above configuration. For example, the method of manufacturing an optical device of the present application can provide an optical device including a known configuration such as a retardation layer, an optical compensation layer, an antireflection layer, and a hard coating layer at an appropriate position.

The optical device manufactured by the method of manufacturing the optical device of the present application can be used for various purposes, for example, eyewear such as sunglasses or eyewear for AR (Argumented Reality) or VR (Virtual Reality). , It can be used for exterior walls of buildings or sunroofs for vehicles.

In one example, the optical device may itself be a sunroof for a vehicle.

For example, in a vehicle including a vehicle body in which at least one opening is formed, the optical device or a vehicle sunroof mounted on the opening may be mounted and used.

The present application provides a method of bonding a laminate capable of preventing wrinkles in a thermoplastic adhesive layer.

1 is a diagram illustrating a method of manufacturing an optical device of the present application by way of example.
2 and 3 are diagrams showing the locations where the temperature was measured in the bonding process.

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

Example 1.

As shown in FIG. 1, a first translucent base layer 160, a first adhesive layer 150, an optical element layer 142, a polarizer 142, a second adhesive layer 130, and a second translucent base layer 120 ) Were sequentially stacked, and an adhesive layer 140 was also disposed on the side of the optical element layer 142 to prepare a laminate. In addition, process substrate layers 110 and 170 are stacked outside each of the first and second translucent substrate layers 120 and 160.

In the above, soda lime glass having a thickness of about 8 cm was used as the first light-transmitting substrate layer, and tempered glass glass having a thickness of about 8 cm was used as the second light-transmitting substrate layer.

As the process substrate, an aluminum metal plate having a thickness of about 5 mm was used.

In the above, the thermal conductivity of each of the soda lime glass, tempered glass glass, and aluminum metal plate was about 1.0 W/mK, about 1.1 W/mK, and about 126 W/mK, respectively.

On the other hand, as the adhesive layer, a sheet-like thermoplastic polyurethane (TPU: thermoplastic polyurethane, Covestro's TPU) having a thickness of 380 μm was used.

In addition, in the above, an active liquid crystal device was used as the optical device layer, and a known PVA (poly(vinyl alcohol))-based absorption polarizer was used as the polarizer. In the active liquid crystal device, a guest host layer was formed between two COP (cycloolefin polymer) films in which an ITO (Indium Tin Oxide) electrode layer and an alignment layer were sequentially formed on the surface thereof. The cell gap of the active liquid crystal element was about 12 μm, and as a guest host layer, a nematic liquid crystal having a dielectric anisotropy of about -4.9 as a liquid crystal compound host, and a dichroic dye having a refractive index anisotropy of about 0.132, and a dichroic ratio of about 6.5 A black dye of about 8 to 8 was formed by applying a guest host mixture in which a weight ratio of 98.7:1.3 (nematic liquid crystal: dichroic dye) was mixed.

The laminate was put in an autoclave and bonded by pressing under vacuum conditions (750 mmHg).

At this time, the temperature condition is, after raising the temperature from room temperature (about 25°C) to about 100°C at a temperature increase rate of about 5°C/min, maintaining the temperature at 100°C for about 100 minutes, and then again. It was cooled to room temperature at a temperature reduction rate of about -1.6°C/min.

In addition, the pressure applied to the laminate was controlled to about 2 bar.

As a result of visually observing the manufactured optical device, no wrinkles were observed at the ends.

Comparative Example 1.

The laminate was bonded in the same manner as in Example 1, except that the process substrate was not disposed outside the first and second translucent substrate layers.

As a result of visually observing the manufactured optical device, severe wrinkles were observed at the ends.

Test Example 1. Comparison of temperature change

The temperature profile of each part in the bonding process in Example 1 and Comparative Example 1 was examined. Specifically, temperature measurement probes 180 were formed at portions indicated by dotted lines in FIGS. 2 and 3, and temperature changes were measured for each portion during the heating, constant temperature, and temperature reduction processes. The measurement results are shown in Tables 1 to 4 below.

As can be seen from Tables 1 and 2, when an aluminum metal plate is used as a process substrate layer and bonded together, it can be seen that the temperature deviation for each part is maintained within about 5 °C during the process of heating up, constant temperature, and reduced temperature. On the other hand, as can be seen from Tables 3 and 4, in the case of Comparative Example 1, it can be seen that a large temperature deviation occurs for each part during the heating, constant temperature, and reduced temperature process, and wrinkles and the like occur due to the temperature deviation.

Example 1-Heating and incubation step Time (minutes) 0 15 30 45 60 75 Temperature by location
(˚C) center 18.6 30.3 49.6 65.6 75.8 83.6 middle 17.9 30 50.6 68.7 76.2 83.5 edge 18.8 32.6 54.2 68.4 78.3 85.1

Example 1-temperature reduction step Time (minutes) 0 15 30 45 Temperature by location
(˚C) center 92.9 95.1 91.6 84.8 middle 92.3 94.4 90.6 83.5 edge 93.2 95 90.2 82.3

Comparative Example 1-Heating and constant temperature step Time (minutes) 0 15 30 45 60 75 Temperature by location
(˚C) center 17.8 31.4 55.8 71.5 82 88.5 middle 18.1 33 58.5 74.4 84.5 90.8 edge 19.2 36.4 65.9 82.5 91.3 95.8

Comparative Example 1-Temperature reduction step Time (minutes) 0 15 30 45 60 Temperature by location
(˚C) center 96.6 94.2 84.6 70.7 56.4 middle 97.6 94.6 84.3 69.5 54.7 edge 99.9 95.4 82.5 65.5 49.3

Claims (18)

A method for manufacturing an optical device comprising an optical element layer encapsulated by an adhesive layer between a first and a second translucent base layer disposed oppositely,
Applying heat to the laminate including the first light-transmitting substrate layer, the first adhesive layer, the optical element layer, the second adhesive layer, and the second light-transmitting substrate layer sequentially laminated, while applying a pressure in the thickness direction of the laminate. It includes the step of bonding the laminate by adding,
A method of manufacturing an optical device in which the bonding is performed in a state in which a process base layer having a higher thermal conductivity than the light-transmitting base layer is disposed outside at least one of the first and second light-transmitting base layers in the bonding process . The method for manufacturing an optical device according to claim 1, wherein the adhesive layer encapsulates the optical element layer while surrounding the upper surface, the lower surface, and the side surface of the optical element layer. The method for manufacturing an optical device according to claim 1, wherein the laminate further comprises a third adhesive layer disposed on a side surface of the optical element layer. The method for manufacturing an optical device according to claim 1, wherein the first and second translucent base layers are each independently a soda-lime glass layer, a lead glass layer, a soda alumina glass layer, an alkali borosilicate glass layer, or a borosilicate alumina glass layer. The optical device of claim 1, wherein the optical element layer comprises a liquid crystal host and an anisotropic dye guest, and has an active liquid crystal layer capable of switching between a first alignment state and a second alignment state. Manufacturing method. The method for manufacturing an optical device according to claim 5, wherein the laminate further comprises a polarizer disposed between the first and second translucent base layers. The optical device according to claim 6, wherein the polarizer is arranged such that an angle formed by an average optical axis in the first alignment state of the active liquid crystal layer and a light absorption axis of the polarizer is in a range of 80 degrees to 100 degrees or 35 degrees to 55 degrees. Device manufacturing method. The method of claim 6, wherein the laminate comprises the first light-transmitting base layer, the first adhesive layer, the optical element layer, the second adhesive layer, the polarizer, the fourth adhesive layer, and the second light-transmitting layer sequentially stacked. A method of manufacturing an optical device including a base layer. The method for manufacturing an optical device according to claim 8, wherein the laminate further comprises a third adhesive layer disposed on a side surface of the optical element layer. The method of claim 1, wherein the adhesive layer is a thermoplastic polyurethane adhesive layer, a thermoplastic polyamide adhesive layer, a thermoplastic polyester adhesive layer, a thermoplastic polyolefin adhesive layer, or an ethylene vinyl acetate adhesive layer. The method for manufacturing an optical device according to claim 1, wherein the bonding is performed in a state in which the eutectic base layer is disposed outside both the first and the second light-transmitting base layer. The method of claim 1, wherein the process substrate layer has a thermal conductivity in the range of 5 W/mK to 500 W/mk. The optical device according to claim 1, wherein the process base layer is a stainless steel base layer, an aluminum base layer, a tungsten base layer, an iron base layer, a cast iron base layer, a carbon steel base layer, a copper base layer, a bronze base layer or a lead base layer Manufacturing method. The method of claim 1, wherein the step of applying heat to the laminate in the bonding process includes a step of increasing temperature, step of constant temperature, and step of reducing temperature in sequence. The method of claim 14, wherein the heating step is performed for a time in the range of 10 minutes to 30 minutes, the incubation step is performed for a time in the range of 10 minutes to 5 hours, and the temperature reduction step is performed for a time in the range of 10 minutes to 100 minutes. Method of manufacturing an optical device performed during. The method for manufacturing an optical device according to claim 14, wherein the temperature is maintained at a temperature in the range of 70°C to 200°C in the constant temperature step. The method for manufacturing an optical device according to claim 1, wherein the bonding step is performed under a pressure of 500 to 2,000 mmHg. The method of claim 1, wherein the pressure applied to the laminate in the bonding process is in the range of 1.5 bar to 10 bar.

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