KR20210020809A - Diffraction light guide plate and manufacturing method thereof the same - Google Patents

Abstract

The present invention relates to a diffraction light guide plate having excellent thickness uniformity and flatness, excellent visibility due to low haze, and excellent mechanical properties such as hardness and strength of a pencil, and a manufacturing method of the diffraction light guide plate. The diffraction light guide plate includes an optical layer wherein a diffraction grating pattern is formed on one surface thereof.

Description

A method for manufacturing a diffractive light guide plate and a diffractive light guide plate TECHNICAL FIELD [0002] Diffraction light guide plate and manufacturing method of diffraction light guide plate

The present invention relates to a diffractive light guide plate and a method of manufacturing a diffractive light guide plate.

Recently, a device for providing a 3D image to a user has been developed using a virtual reality device and an augmented reality device.

The virtual reality device or the augmented reality device may form a diffraction light guide pattern on lenses such as general glasses to display a desired image to a user.

In general, a lens for a virtual reality device or an augmented reality device uses glass having a high refractive index, and the glass may have a high refractive index, light transmittance, flatness and strength, but when it is damaged, it may cause fatal damage to the user's eyes. It can be used, and due to its high density, it is heavy in weight, which makes it difficult to wear for a long time.

Accordingly, there is a need for a study on a lens that has high light transmittance and a high refractive index so that it can be used as a virtual reality device or an augmented reality device, and is light and relatively safe when damaged.

In the case of a high-refractive plastic to replace glass, it is very light and capable of implementing various colors, but there is a problem that physical properties such as surface flatness and thickness uniformity are not significantly compared to those of conventional glass.

Furthermore, during the imprint process of forming the diffraction grating, shape deformation occurs due to low strength, or when a large amount of inorganic particles is used to implement high refractive index, it not only causes haze of the final product, but also the interface adhesion between the substrate and the high refractive plastic is poor. There is a problem in that it is difficult to secure high pencil hardness, and research for improvement thereof is required.

An object of the present invention is to provide a diffractive light guide plate having excellent thickness uniformity and flatness, low haze, excellent mechanical properties such as pencil hardness and strength, and capable of implementing a high refractive index while being lighter than glass or tempered glass.

In addition, the present invention is to provide a diffractive light guide plate manufacturing method for manufacturing the diffractive light guide plate by a simple process.

In this specification, a diffraction grating pattern includes an optical layer formed on one surface, and the diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer, and the difference in refractive index between the diffraction grating pattern and one surface of the optical layer Is 0.01 or less, and the optical layer on which the diffraction grating pattern is formed on one surface is a diffractive light guide plate, which is a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups.

In addition, in the present specification, diffraction included in the flat lower substrate, the flat upper substrate, the buffer spacer positioned between the flat lower substrate and the flat upper substrate, and the flat lower substrate or the flat upper substrate Preparing a mold equipment including a template in which a lattice pattern is engraved, and in which a molding space is partitioned by the buffer spacer; Buffering the curable composition in the molding space; And compressing the curable composition under the load of the flat upper substrate, and curing the curable composition, wherein the curable composition comprises an episulfide compound, a thiol compound, and an aromatic ring compound having at least two hydroxyl groups. Including, compressing the curable composition under the load of the flat upper substrate, and curing the curable composition is provided a diffraction light guide plate manufacturing method performed to satisfy Equation 1 below.

[Equation 1]

{(Load of flat upper substrate + curing contraction force of curable composition) Х 0.95} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing contraction force of curable composition) Х 1.05}.

Hereinafter, a method of manufacturing a diffractive light guide plate and a diffractive light guide plate according to a specific embodiment of the present invention will be described in more detail.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

Further, when a member is said to be located "on" another member, this includes not only the case where the member is in contact with the other member, but also the case where another member exists between the two members.

In addition, the terms "step (to)" or "step of" to the extent used do not mean "step for".

The definition of “episulfide compound” used herein refers to a compound containing one or more episulfides, wherein episulfide refers to a compound in which an oxygen (O) atom of the epoxide is substituted with a sulfur (S) atom.

The definition of “thiol compound” used herein refers to a compound containing one or more thiol groups (-SH).

In the present specification, “curable” means both thermosetting and photocuring, and “curable composition” means a composition capable of thermosetting and/or photocuring.

In the present specification, high refraction means about 1.6 or more in a wavelength range of 350 to 800 nm or a wavelength of 532 nm.

According to one embodiment of the invention, a diffraction grating pattern includes an optical layer formed on one surface, and the diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer, and the diffraction grating pattern and the optical layer are The difference in refractive index between one surface is 0.01 or less, and the optical layer on which the diffraction grating pattern is formed is a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups, a diffractive light guide plate may be provided. have.

In the optical layer in which the diffraction grating pattern included in the diffraction light guide plate according to the embodiment is formed on one surface, the diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer, and this optical layer is an episulfide compound, A thiol compound and an aromatic ring compound having two or more hydroxyl groups In the case of a continuous phase of the containing polymer, mechanical properties such as pencil hardness and strength of the diffractive light guide plate are excellent. In addition, since there is little difference in refractive index between the diffraction grating pattern and one surface of the optical layer, there is no problem of decrease in transmittance or haze caused by the interface, and light incident on the diffraction light guide plate (i.e., light guide The efficiency of total reflection of) light) in the diffractive light guide plate is increased, and a high-resolution image with higher luminance can be displayed when this is used in a virtual reality device or the like.

In the case of a conventional diffractive light guide plate, after forming a resin layer by applying and drying a resin composition for imprinting on a substrate, the pattern portion is formed through a process of imprinting a template in which the diffraction grating pattern is engraved on the resin layer. Although the light guide plate was manufactured, it was difficult to secure mechanical properties such as pencil hardness due to the presence of an interface between the substrate and the pattern portion in the diffractive light guide plate manufactured by this method, and the interface adhesion was poor. However, in the diffraction light guide plate according to the embodiment, the diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer, so that excellent mechanical properties such as high pencil hardness and strength may be exhibited.

In addition, since the optical layer in which the diffraction grating pattern included in the diffraction light guide plate is formed on one surface is a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups, it is similar to glass. It has a high refractive index and can be used as a diffractive light guide lens of a wearable device. For this reason, it is possible to prevent problems that occur due to breakage of the conventional glass, and problems that are difficult to wear for a long time due to the heavy weight of the glass. Furthermore, the diffractive light guide plate can achieve a high refractive index even if it does not contain additional inorganic particles, and thus, does not cause haze due to inorganic particles, and has low haze, so that visibility is high. In addition, the diffractive light guide plate may be manufactured by a method of manufacturing a diffractive light guide plate, which will be described later, and thus can have excellent thickness uniformity and flatness.

Since the optical layer formed on one surface of the diffraction grating pattern is a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups, the difference in refractive index between the diffraction grating pattern and one surface of the optical layer May be 0.01 or less, 0.05 or less, 0.001 or less, or 0.001 to 0.0001. If the difference in refractive index between the diffraction grating pattern and one surface of the optical layer exceeds 0.01, a problem of lowering of transmittance resulting from an interface between the diffraction grating pattern and one surface of the optical layer or haze may occur. Therefore, since the difference in refractive index between the diffraction grating pattern and one surface of the optical layer satisfies the above range, there is no problem of lowering of transmittance or generation of haze originating from the interface, and total reflection of light guided by light. When the efficiency is improved and the device is used in a virtual reality device, an image with higher brightness can be displayed.

1 is a schematic cross-sectional view of an optical layer included in a diffractive light guide plate according to the embodiment. Specifically, the optical layer 300 has a diffraction grating pattern 200 formed on one surface thereof, and the diffraction grating pattern may include one or more pattern units 400.

Specifically, the diffraction grating pattern 200 may include two or more pattern units 400 that are spaced apart from one side along the other side direction. The pattern unit is not particularly limited as long as it is a pattern capable of diffraction of waved light, but may be a grid pattern having a shape such as a square column, a hexagonal column, a triangular pyramid, a cone, an elliptical cone, or a hemisphere, or a bar or stripe pattern. I can. Meanwhile, the shape of the cross section of the pattern unit is not particularly limited, but may have, for example, a square, a triangle, a rhombus, a trapezoid, and a parabolic shape. The direction of the cross section of the pattern unit may be a direction perpendicular to the diffraction light guide plate.

In addition, a pitch between the pattern units 400 included in the diffraction grating pattern 200 is 0.1 to 1 µm, 0.2 to 0.9 µm, 0.3 to 0.8 µm, or 0.4 to 0.7 µm, and the height May be 0.1 to 1 µm, 0.2 to 0.9 µm, 0.3 to 0.8 µm, or 0.4 to 0.7 µm.

The pitch means an interval at which the pattern unit 400 is repeated, and specifically, may mean a length between a point of one pattern unit and a point of another pattern unit adjacent thereto. In addition, one point of one pattern unit and one point of the other pattern unit may mean positions corresponding to each other between the pattern units, and the direction of the length is a direction parallel to the optical layer 300. In addition, the direction of the height is a direction perpendicular to the optical layer.

When two or more pattern units 400 included in the diffraction grating pattern 200 are included, the shape of the two or more pattern units may be the same, and specifically, the shape, period, height, etc. of the cross section may be the same. have. For this reason, the amount of light diffracted in the entire area of the diffractive light guide plate may be the same. In addition, the shape of the two or more pattern units 400 included in the diffraction grating pattern 200 may be different, and specifically, the shape of the cross section may be the same, but the period and height may be different, and the period may be the same. The shape and height of the cross section may be different.

The thickness of the optical layer 300 may be 0.1 to 10 mm, 0.2 to 9 mm, 0.3 to 8 mm, 0.4 to 7 mm, or 0.5 to 5 mm. If the thickness of the optical layer 300 is too thin, the number of times that light incident on the diffractive light guide plate including the optical layer is unnecessarily totally reflected inside the diffractive light guide plate increases, and thus, the luminance of the outgoing light emitted from the diffractive light guide plate is increased. Therefore, when the diffractive light guide plate is used in a virtual reality device or the like, the resolution may decrease. On the other hand, if the thickness of the optical layer is too thick, the transmittance of external light to the diffractive light guide plate including the optical layer decreases, so that the luminance of the external image is lowered, thereby reducing visibility.

The optical layer 300 on which the diffraction grating pattern 200 is formed may be a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups.

The diffraction light guide plate has an optical layer in which the diffraction grating pattern is formed on one side in a one-step process by a method of manufacturing a diffraction light guide plate to be described later, and the diffraction grating pattern is integrated without an interface on one side of the optical layer. The optical layer and the diffraction grating pattern formed on one surface of the optical layer may include a cured product of the same curable composition. That is, the optical layer on which the diffraction grating pattern is formed corresponds to a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups. In addition, since the continuous phase of the polymer can implement a high refractive index without including inorganic particles, it is possible to prevent a problem related to haze caused when a large amount of inorganic particles are used.

The weight ratio of the thiol compound and the aromatic ring compound having two or more hydroxyl groups may be 5:5 to 9:1, 7:3 to 8.5:1.5, or 7:3 to 8:2. If the weight ratio of the thiol compound and the aromatic cyclic compound having two or more hydroxyl groups is less than 5:5, it may be difficult to implement a high refractive index of the diffraction light guide plate, and if it exceeds 9:1, the curing rate control during curing of the curable composition comprising them It becomes difficult, and there is a problem that streak phenomenon occurs in the diffractive light guide plate.

The episulfide compound may include a compound represented by Formula 1 below.

[Formula 1]

In Formula 1,

R ₁ and R ₂ are each independently hydrogen or alkyl having 1 to 10 carbon atoms,

R ₃ and R ₄ are each independently a single bond or an alkylene having 1 to 10 carbon atoms,

a is an integer from 0 to 4,

b is an integer from 0 to 6.

The episulfide compound represented by Formula 1 has an aliphatic chain-like skeleton in which episulfide is connected at both ends of the molecule, and in the aliphatic chain, an alkylene group is connected by a sulfur (S) atom. ether) may have a repeating unit.

The episulfide compound may contain a high content of sulfur (S) atoms having high atomic refraction in the molecule due to the specific chemical structure described above, and the refractive index of the diffraction light guide plate can be increased by such a high content of sulfur atoms. Further, the episulfide compound can be cured by ring-opening polymerization, and the alkylene sulfide group formed by ring-opening polymerization of the episulfide group can further increase the high refractive index of the diffraction light guide plate.

Meanwhile, in Formula 1, R ₁ and R ₂ may each independently be hydrogen or a methyl group, but are not limited thereto.

In addition, R ₃ and R ₄ may each independently be a single bond, methylene, ethylene, propylene, isopropylene, butylene, or isobutylene, but are not limited thereto.

In addition, a and b may each independently be 0 or 1.

A in Formula 1 relates to the number of carbon atoms of the alkylene group contained in the thioether repeating unit.When a is too large, the length of the carbon chain in the molecule becomes longer, and the glass transition temperature of the diffraction light guide plate is lowered. Accordingly, there may be a problem in that the heat resistance of the diffractive light guide plate is lowered, and also, a problem in that the refractive index of the diffractive light guide plate is lowered due to a lower content of sulfur may occur.

B in Formula 1 is the number of repetitions of thio ether repeating units in which an alkylene group is connected by a sulfur (S) atom, and if b is too large, the chain length of the molecule becomes longer and the diffraction light guide plate during curing The glass transition temperature of is lowered, and accordingly, a problem in that the heat resistance of the diffractive light guide plate is lowered may occur.

In addition, the compound represented by Chemical Formula 1 may be used alone, or two or more may be used in combination.

The episulfide compound is, for example, bis(β-epithiopropyl)sulfide, bis(β-epithiopropyl) disulfide, bis(β-epithiopropylthio)methane, 1,2-bis(β-epi Thiopropylthio)ethane, 1,3-bis(β-epithiopropylthio)propane, 1,4-bis(β-epithiopropylthio)butane, etc., but may contain at least one selected from the group consisting of, but the present The invention is not necessarily limited thereto.

The content of the episulfide compound may be 50 to 99% by weight, 60 to 95% by weight, or 70 to 90% by weight based on 100% by weight of the total diffraction light guide plate. When the content of the episulfide compound is too large, there is a problem in that the glass transition temperature of the diffraction light guide plate is lowered and the yellow index (YI) is increased. On the other hand, when the content of the episulfide compound is too small, the glass transition temperature of the diffraction light guide plate is lowered and the yellow index (YI) is increased, and mechanical properties such as hardness and strength may be deteriorated.

The thiol compound may include at least one selected from compounds represented by Formulas 2 and 3 below.

[Formula 2]

In Chemical Formula 2,

R ₅ and R ₆ are each independently a single bond or an alkylene having 1 to 10 carbon atoms,

c is an integer from 0 to 4,

d is an integer from 0 to 6,

[Formula 3]

In Chemical Formula 3,

Ring A is a 5-membered or 6-membered aromatic hetero ring containing at least one of nitrogen (N) and sulfur (S) atoms,

e is an integer from 1 to 3,

Specifically, the thiol compound represented by Formula 2 has an aliphatic chain-like skeleton in which thiol groups (-SH) are connected at both ends of the molecule, and in the aliphatic chain, an alkylene group is formed by a sulfur (S) atom. It may have a repeating unit in the form of a thio ether to be connected.

Meanwhile, in the thiol compound represented by Chemical Formula 3, at least one thiol group may be connected to a 5- or 6-membered aromatic ring containing a hetero atom such as nitrogen (N) and/or sulfur (S).

The thiol compound represented by Formula 2 or 3 may react with an episulfide group to form a disulfide bond or the like in a curing reaction with the episulfide compound, that is, a ring-opening polymerization reaction of an episulfide group. By including a high content of sulfur (S) atoms having a high refractive index, the refractive index of the diffractive light guide plate may be further increased, and the physical strength of the diffractive light guide plate may be improved.

Meanwhile, in Formula 2, R ₅ and R ₆ may each independently be a single bond, methylene, ethylene, propylene, isopropylene, butylene, or isobutylene, but are not limited thereto.

In addition, c and d may each independently be 0 or 1.

C in Formula 2 relates to the number of carbon atoms in the alkylene group contained in the thioether repeating unit. When c is too large, the length of the carbon chain in the molecule becomes longer, resulting in a lower glass transition temperature of the diffraction light guide plate. Accordingly, there may be a problem in that the heat resistance of the diffractive light guide plate is lowered, and also, a problem in that the refractive index of the diffractive light guide plate is lowered due to a lower content of sulfur may occur.

D in the formula (2) is the number of repeating thio ether repeating units in which the alkylene group is connected by a sulfur (S) atom, and if d is too large, the chain length of the molecule becomes longer and the diffraction light guide plate is advantageous. The transition temperature is lowered, and accordingly, there may be a problem in that the heat resistance of the diffractive light guide plate is deteriorated.

In addition, in Formula 3, the A ring may be pyridine, pyrimidine, triazine, imidazole, thiophene, thiazole, or thiadiazole, but is not limited thereto.

In addition, e may be 2 or 3.

In addition, the compounds represented by Formula 2 or 3 may be used alone or in combination of two or more.

The thiol compound may include, for example, at least one selected from the following compounds.

The content of the thiol compound may be 1 to 30% by weight, 5 to 25% by weight, or 7 to 10% by weight based on 100% by weight of the total diffraction light guide plate. If the content of the thiol compound is too high, the glass transition temperature of the diffraction light guide plate is lowered, the yellow index (YI) is increased, and physical properties such as hardness and strength are deteriorated. On the other hand, when the content of the thiol compound is too small, there is a problem of lowering the glass transition temperature of the diffraction light guide plate and increasing the yellow index (YI).

The aromatic ring compound having two or more hydroxyl groups may include at least one selected from compounds represented by the following Chemical Formulas 4 and 5.

[Formula 4]

In Chemical Formula 4,

R ₇ and R ₈ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, and 1 to 40 carbon atoms. Alkenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S,

f and g are each independently an integer of 1 to 7,

h and i are each independently an integer of 0 to 6,

f+h is an integer of 7 or less,

g+i is an integer of 7 or less,

[Formula 5]

In Chemical Formula 5,

Ar ₁ and Ar ₂ are each independently an aryl having 6 to 60 carbon atoms in which one or more hydroxyl groups are substituted,

R ₉ and R ₁₀ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, and having 1 to 40 carbon atoms. Alkenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S,

m and n are each independently an integer of 0 to 4.

Specifically, the aromatic cyclic compound having two or more hydroxyl groups represented by Formula 4 has a skeleton to which two naphthalenes are linked, and one or more hydroxyl groups may be linked to each naphthalene.

Meanwhile, the aromatic cyclic compound having two or more hydroxyl groups represented by Chemical Formula 5 may exhibit a form in which two aryl groups having one or more hydroxyl groups substituted at the 9th position of fluorene are substituted.

The aromatic cyclic compound having two or more hydroxyl groups represented by Formula 4 or 5 may realize a high refractive index of the diffraction light guide plate by a conjugation system of aromatic functional groups, and due to such aromatic functional groups, diffraction Even if the content of the sulfur atom decreases as the aromatic cyclic compound is included in the light guide plate, a decrease in the refractive index may be minimized, and further, the glass transition temperature (Tg) of the diffraction light guide plate may be increased to improve mechanical properties.

Meanwhile, in Formula 4, R ₇ and R ₈ may each independently be deuterium, halogen, cyano, nitrile, nitro, amino, methyl, or ethyl, but are not limited thereto.

In addition, f and g may each independently be 1 or 2.

In addition, h and i may each independently be 0 or 1.

In addition, in Formula 5, Ar ₁ and Ar ₂ may each independently be phenyl or naphthalenyl substituted with 1 or 2 hydroxyl groups, but are not limited thereto.

In addition, R ₉ and R ₁₀ may each independently be deuterium, halogen, cyano, nitrile, nitro, amino, methyl, or ethyl, but are not limited thereto.

In addition, m and n may each independently be 0 or 1.

In addition, the compounds represented by Formula 4 or 5 may be used alone or in combination of two or more.

The aromatic ring compound having two or more hydroxyl groups may include, for example, at least one selected from the following compounds.

The content of the aromatic cyclic compound having two or more hydroxyl groups may be 0.1 to 10% by weight, 0.5 to 5% by weight, or 1 to 3% by weight based on 100% by weight of the total diffraction light guide plate. If the content of the aromatic cyclic compound having two or more hydroxyl groups is too large, there is a problem that the refractive index of the diffraction light guide plate is lowered, and if the content is too small, the curing reaction rate is too fast, and thus streaking occurs in the diffractive light guide plate.

In addition, the continuous phase of the polymer may further include a catalyst. Examples of the catalyst include an amine, an ammonium salt, or a phosphate, and specifically, for example, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4- Methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methyl Imidazole derivatives such as midazole; Dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethyl benzylamine, 4-methoxy-N,N-dimethylbenzylamine, 4-methyl-N,N-dimethylbenzylamine, N, Amine compounds such as N-dicyclohexylmethylamine; Hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; And phosphorus compounds such as triphenylphosphine. In addition, as commercially available ones, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ manufactured by Shikoku Kasei Kogyo (all are brand names of imidazole compounds), U-CAT3503N, UCAT3502T manufactured by San Apro (All are trade names of dimethylamine block isocyanate compounds), DBU, DBN, U-CATSA102, and U-CAT5002 (all bicyclic amidine compounds and salts thereof), and the like.

The content of the catalyst may be 0.001 to 10% by weight, 0.01 to 5% by weight, or 0.1 to 1% by weight, based on 100% by weight of the total diffraction light guide plate.

In addition, the diffractive light guide plate may further include other additives used to impart a specific function to a display substrate in the technical field to which the present invention pertains, in addition to this.

The continuous phase of the polymer may be a photo-cured product or a thermo-cured product.

One surface of the diffraction grating pattern 200 and the optical layer 300 may have a refractive index of 1.65 or more, 1.70 or more, 1.72 or more, or 1.73 to 2.5, respectively, at a wavelength of 532 nm. In the case of a general glass substrate, the photorefractive index is 1.65 or more at a wavelength of 532 nm. Accordingly, the diffraction light guide plate including the optical layer on which the diffraction grating pattern is formed on one surface may be made of a plastic material, but can implement a light refractive index equivalent to that of a glass substrate, thereby replacing a glass substrate. In addition, when used as a lens of a wearable device due to its high optical refractive index, optical loss can be minimized and optical information can be moved.

In addition, the glass transition temperature of the diffraction light guide plate may be 40°C or higher, 40°C to 150°C, 50°C to 130°C, or 80 to 100°C. In the case of a wearable device, continuous image transmission and output may be performed, and accordingly, the temperature of the lens may increase. Meanwhile, since the diffractive light guide plate may have a glass transition temperature of 40° C. or higher, even if it is used as a lens of a wearable device, a change in physical properties according to temperature can be minimized to achieve high durability.

The haze of the diffractive light guide plate may be 4.0% or less, 3.0% or less, 2.0% or less, or 1.5 to 0.01%. Since the diffractive light guide plate has a refractive index of 1.65 or higher without including inorganic particles, it does not cause haze and has high visibility.

In addition, the pencil hardness of the diffractive light guide plate may be HB or higher, H or higher, or 2H or higher. Since the diffraction grating pattern 200 is formed in an integrated structure without an interface on one surface of the optical layer 300, mechanical properties such as pencil hardness and strength are excellent.

In addition, although the diffraction light guide plate includes one or more pattern units, the thickness variation may be 3.0% or less, 2.5% or less, 1% or less, or 0.1 to 1%. As the value of the thickness deviation is lower, the thickness uniformity of the diffractive light guide plate is higher, and thus the diffractive light guide plate according to the embodiment may have excellent thickness uniformity.

In addition, the thickness deviation of the diffractive light guide plate can be derived as in the following general formula 1.

[General Formula 1]

Thickness deviation (%) = (maximum deviation/average thickness) Х 100

The maximum thickness or minimum thickness can be measured using a contact measurement method using Mitsutoyo's Digimatic Thick 547-401 equipment at 25 ℃ and 50 RH% atmosphere. Alternatively, the maximum thickness or minimum thickness can be measured at 25° C. and 50 RH% using a non-contact measurement method using Micro-Epsilon's IFS-2405-1 or IFC-2451-MP equipment.

On the other hand, the average thickness is at 25 ℃ and 50 RH% atmosphere, using a contact measurement method using Mitsutoyo's Digimatic Thick 547-401 equipment, a random point of a randomly placed specimen as the origin, a radius of 10 mm and 22.5 degrees. It may be an average value of the thickness measured at intervals. Alternatively, the average thickness is at 25 ℃ and 50 RH% atmosphere, using a non-contact measurement method using FiberPro's OWTM (Optical Wafer Thickness Measurement System) equipment, using a random point of the randomly placed specimen as the origin, horizontal and vertical It may be an average value of the thickness measured at 1 mm intervals for each.

The warp of the diffractive light guide plate may be 100 µm or less, 50 µm or less, 20 µm or less, 10 µm or less, or 0.1 to 10 µm. The diffractive light guide plate manufactured by the method of manufacturing the diffractive light guide plate according to the above embodiment may satisfy the warp range, and when the warp of the diffractive light guide plate exceeds 100 μm, the reflection angle of light incident on the diffractive light guide plate cannot be maintained. When used in a device, the resolution may be degraded.

Warp is a numerical representation of the overall curvature of the diffractive light guide plate, and can be derived as in General Formula 2 below.

[General Formula 2]

Warp = maximum deviation between center plane and reference plane-minimum deviation between center plane and reference plane

In General Formula 2, the center plane is a plane corresponding to the middle of the thickness of the diffraction light guide plate, and the reference plane is a plane calculated by least squares fit with respect to the center plane in the measurement area. Accordingly, the warp corresponds to a difference between the maximum and minimum deviations between the reference plane and the center plane.

Meanwhile, the central surface may be derived using a non-contact measurement method using Fiber Pro's OWTM (Optical Wafer Thickness Measurement System) equipment in an atmosphere of 25° C. and 50 RH%.

In addition, the diffractive light guide plate may have a transmittance, specifically, a transmittance value of 80% or more, 80 to 99%, or 85 to 90%, as measured according to JIS K 7361 when the thickness is 1 mm. .

In addition, the diffractive light guide plate has a yellowness (YI; Yellow Index), specifically, a yellowness of 1 to 30, 2 to 22, 2.1 to 10, 2.2 to 5, or 2.3 to 4, as measured according to ASTM E313-1973, May exhibit low yellowness.

The diffractive light guide plate may be for a diffractive light guide lens of a wearable device. Specifically, the wearable device is an augmented reality device or a virtual reality device, and the diffraction light guide plate may be included as a lens of the wearable device, and due to the diffraction grating pattern included in the diffraction light guide plate, input, movement and Transmission can be facilitated.

According to another embodiment of the present invention, a method of manufacturing the above-described diffractive light guide plate is provided.

The present inventors believe that when a substrate is manufactured by injecting a curable composition into a conventional mold equipment and then curing, the cured product is peeled off the mold substrate during curing due to curing shrinkage of the curable composition, leaving peel marks on the surface of the substrate to be manufactured. , Recognizing that there is a problem that the thickness uniformity is greatly damaged, and also, after forming a resin layer by applying and drying a resin composition for imprint on a substrate manufactured by a molding process, the imprint process is performed on the resin layer. In the case of manufacturing a diffractive light guide plate, it was recognized that it was difficult to secure high pencil hardness due to poor interfacial adhesion between the substrate and the imprinted resin layer, and the present invention was developed.

The method of manufacturing a diffractive light guide plate according to another embodiment includes: a flat lower substrate, a flat upper substrate, a buffer spacer positioned between the flat lower substrate and the flat upper substrate, and the flat lower substrate or the flat plate Preparing a mold equipment including a template in which a diffraction grating pattern included in an upper substrate is engraved, and in which a molding space is partitioned by the buffer spacer;

Buffering the curable composition in the molding space; And

Compressing the curable composition under the load of the flat upper substrate and curing the curable composition; Including,

The curable composition includes an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups,

Compressing the curable composition under the load of the flat upper substrate, and curing the curable composition satisfies Equation 1 below.

[Equation 1]

{(Load of flat upper substrate + curing contraction force of curable composition) Х 0.95} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing contraction force of curable composition) Х 1.05}.

In the method of manufacturing a diffractive light guide plate according to another embodiment, due to the use of the buffer spacer, the cured product is peeled off from the flat lower substrate and the flat upper substrate of the mold equipment according to the curing shrinkage of the curable composition when the curable composition is cured. By minimizing the phenomenon, it is possible to manufacture a diffractive light guide plate having very excellent surface flatness and thickness uniformity.

In addition, due to the use of a template in which the diffraction grating pattern is engraved, the curable composition is cured and the diffraction grating pattern engraved on the template is compressed on the top or bottom of the cured product. A lattice pattern can be formed. For this reason, it is not necessary to perform an additional resin layer formation process and imprint process, and a diffraction light guide plate including an optical layer in which a diffraction grating pattern is formed on one surface can be manufactured by a simple one-step process, and the diffraction grating pattern Is excellent in mechanical properties such as pencil hardness and strength because it is formed in an integrated structure without an interface on one surface of the optical layer.

Meanwhile, the compressive stress of the buffer spacer satisfies Equation 1 above. Since the compressive stress of the buffer-type spacer has a difference within 5% of the sum of the load of the flat upper substrate and the curing contraction force of the curable composition, in the curing step of the curable composition, depending on the curing shrinkage of the curable composition The flat upper substrate is brought into close contact with the curable composition. Accordingly, the manufactured diffractive light guide plate exhibits excellent surface flatness, and thus thickness uniformity can be excellently implemented.

In addition, since the compressive stress of the buffer spacer satisfies Equation 1, the template included in the flat lower substrate or the flat upper substrate may also be in close contact with the curable composition, and thus, the intaglio in the template The diffraction grating pattern may clearly appear as a diffraction grating pattern on one side of the cured product.

On the other hand, when the compressive stress of the buffer-type spacer is less than {(load of flat upper substrate + curing contraction force of curable composition) Х 0.95}, curing is completed before equilibrium is reached, resulting in uneven thickness of the diffractive light guide plate, The diffraction grating pattern may not appear clearly. In addition, when the compressive stress of the buffer-type spacer is greater than {(load of the flat upper substrate + curing shrinkage force of the curable composition) Х 1.05}, non-uniformity of shrinkage may occur during curing, resulting in poor appearance characteristics of the diffraction light guide plate.

Specifically, according to an exemplary embodiment of the present invention, Equation 1 may satisfy Equation 1-1, 1-2, or 1-3 below.

[Equation 1-1]

{(Load of flat upper substrate + curing shrinkage force of curable composition) Х 0.97} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) Х 1.03}

[Equation 1-2]

{(Load of flat upper substrate + curing shrinkage force of curable composition) Х 0.98} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) Х 1.02}

[Equation 1-3]

{(Load of flat upper substrate + curing shrinkage force of curable composition) Х 0.99} ≤ Compressive stress of buffer type spacer ≤ {(load of flat upper substrate + curing shrinkage force of curable composition) Х 1.01}

Specifically, the compressive stress of the buffer-type spacer may have a difference within 3%, within 2%, or within 1% of the sum of the load of the flat upper substrate and the curing contraction force of the curable composition, and is manufactured accordingly. The diffractive light guide plate exhibits more excellent surface flatness, and thickness uniformity may be better implemented.

Units of the load of the flat upper substrate, the curing contraction force of the curable composition, and the compressive stress of the buffer spacer may be kgf or N.

The buffer spacer may serve to prevent the cured product of the curable composition from being peeled off from the flat upper substrate due to curing shrinkage of the curable composition. Specifically, the buffer spacer has a compressive stress in consideration of the degree of curing and shrinkage of the curable composition and the load of the flat upper substrate as the curable composition is cured, and thus the load of the flat upper substrate according to the curing shrinkage of the curable composition It is compressed by, and in the step of curing the curable composition, it may serve to maintain a state in which the curable composition and the flat upper substrate are in close contact with each other. In addition, when a template in which the diffraction grating pattern is engraved is included in the flat upper substrate and is positioned on the flat upper substrate, the buffer spacer is in close contact with the template and the curable composition in the step of curing the curable composition. It can play a role in maintaining the status.

The load of the flat upper substrate may be 3.4 N to 34 N, 5.9 N to 27 N, or 7 N to 25 N. When the load of the flat upper substrate is within the above range, deformation due to curing shrinkage during curing of the curable composition can be minimized, reduction in transmittance during photocuring of the curable composition can be minimized, and By minimizing the non-uniformity in discharge of reaction heat during thermal curing, it is possible to induce uniform curing of the curable composition. On the other hand, when the template in which the diffraction grating pattern is engraved is included in the flat upper substrate and is located on the flat upper substrate, the load of the flat upper substrate is a load due to the template in which the diffraction grating pattern is engraved. It corresponds to the included load.

In Equation 1, the curing shrinkage force of the curable composition may be measured by the following method. Specifically, using TA's Texure Analyzer equipment at 25°C and 50 RH% atmosphere, after applying a certain amount of the curable composition on the lower jig, lower the upper jig to contact the curable composition to record the initial value of the force. And, after raising the temperature to 90° C. and maintaining it for 5 hours, the final value of the force is recorded, and the value obtained as the difference between the final value of the force and the initial value can be measured.

In Equation 1, the compressive stress of the buffer spacer can be measured in the following manner. Specifically, in an atmosphere of 25°C and 50 RH%, the specimen is deformed ((initial thickness-thickness after deformation)/initial when compressed with a specimen area of 5 Х 5 ㎟ and a compression speed of 1 mm/min using TA's Texture Analyzer. It may be a measure of the force at the moment of reaching the thickness).

The molding space may be partitioned by the buffer spacer. Specifically, when a template in which a diffraction grating pattern is engraved on the flat lower substrate is provided, the molding space is partitioned by the buffer spacer, and an empty space provided between the template and the flat upper substrate is provided. It can mean. Alternatively, when a template in which a diffraction grating pattern is engraved on the flat upper substrate is provided, the molding space is partitioned by the buffer spacer, meaning an empty space provided between the template and the flat lower substrate. can do.

The method of manufacturing the light guide plate according to the other embodiment may include buffering the curable composition in the molding space.

Specifically, the step of buffering the curable composition may include injecting the curable composition into the molding space so that the curable composition is in close contact with the flat lower substrate (or the flat upper substrate) and the template in which the diffraction grating pattern is engraved. It can mean filling enough. In particular, the curable composition may be tightly adhered to the entire surface of the intaglio pattern of the template. Specifically, the step of buffering the curable composition may mean injecting the curable composition in an amount of 95 vol% or more, 97 vol% or more, 99 vol% or more, or 100 vol% to the molding space.

In addition, the step of buffering the curable composition may include injecting the curable composition into a molding space divided into the buffer-type spacer and the flat-type lower substrate, and laminating a flat-type upper substrate including the template; A method of injecting the curable composition into a molding space divided into a flat lower substrate including the buffer spacer and the template, and laminating the flat upper substrate; Alternatively, various methods such as a method of injecting the curable composition by providing an injection hole in the mold equipment may be used.

Meanwhile, the curable composition may be a photocurable composition or a thermosetting composition, and may be applied without limitation as long as it is for manufacturing a diffraction light guide plate. Specifically, the curable composition may be applied without limitation as long as it is capable of manufacturing a diffractive light guide plate using mold casting. For example, the curable composition comprises the above-described episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups. Can include. Specifically, The curable composition may include an episulfide compound represented by Formula 1, a thiol compound represented by Formula 2 or 3, and an aromatic ring compound having two or more hydroxyl groups represented by Formula 4 or 5. On the other hand, the description of Chemical Formulas 1 to 5 is as described in the previous diffraction light guide plate.

In addition, in the photocurable composition, the weight ratio of the thiol compound and the aromatic cyclic compound having two or more hydroxyl groups may be 5:5 to 9:1, 7:3 to 8.5:1.5, or 7:3 to 8:2. . If the weight ratio of the thiol compound and the aromatic ring compound containing two or more hydroxyl groups is less than 5:5, it may be difficult to implement a high refractive index, and if it exceeds 9:1, it is difficult to control the curing rate during curing of the curable composition, resulting in a cured diffraction Streak phenomenon occurs in the light guide plate, and long-term storage of the curable composition may be difficult.

In addition, in the total 100% by weight of the photocurable composition, the content of the episulfide compound may be 50 to 99% by weight, 60 to 95% by weight, or 70 to 90% by weight. If the content of the episulfide compound is too high, the content of the cured product such as a thiol compound is relatively small, resulting in uncured by-products, which lowers the glass transition temperature of the cured diffractive light guide plate and yellowness (YI; Yellow Index). There is a problem of increasing ). On the other hand, if the content of the episulfide compound is too small, the content of the curing agent such as a thiol compound is relatively high, so that the curing agent is not sufficiently dissolved in the curable composition, or uncured by-products are generated. There is a problem of lowering the glass transition temperature of the light guide plate and increasing the yellow index (YI).

In addition, in the total 100% by weight of the photocurable composition, the content of the thiol compound may be 1 to 30% by weight, 5 to 25% by weight, or 7 to 10% by weight. If the content of the thiol compound is too high, the solid thiol compound is not sufficiently dissolved in the curable composition, or the content of other compositions such as the episulfide compound is relatively small, resulting in uncured by-products, etc. There is a problem of lowering the glass transition temperature of the light guide plate and increasing the yellow index (YI). On the other hand, when the content of the thiol compound is too small, the content of other compositions such as the episulfide compound is relatively increased, resulting in uncured by-products, which lowers the glass transition temperature of the cured diffraction light guide plate and reduces yellowness ( There is a problem of increasing the YI; Yellow Index)

In addition, the aromatic ring compound containing two or more hydroxyl groups contained in the photocurable composition is crosslinked by a ring-opening polymerization reaction of two or more hydroxyl groups with the episulfide compound and the thiol compound in the curing reaction with the episulfide compound and the thiol compound. It proceeds, and the curing reaction rate can be controlled because the ring-opening polymerization reaction occurs at a reaction rate that is slower than that of the thiol compound, for example, 1/1,000. In addition, in the aromatic ring compound containing two or more hydroxyl groups, the aromatic ring is a slower reaction rate than the aliphatic hydroxyl group, for example, due to the ring-opening polymerization reaction at a reaction rate of 1/2, the curing reaction rate can be controlled. Therefore, it is possible to prevent the rapid curing reaction from occurring even after mixing the curable composition, so that the curing reaction does not proceed for longer than 7 days at a temperature condition of 0°C for long-term storage, for example, and further, the diffraction light guide plate due to rapid curing It can prevent streak phenomenon in

Further, in 100% by weight of the total photocurable composition, the content of the aromatic cyclic compound including two or more hydroxyl groups may be 0.1 to 10% by weight, 0.5 to 5% by weight, or 1 to 3% by weight. If the content of the aromatic cyclic compound containing two or more hydroxyl groups is too high, there is a problem that it is not sufficiently dissolved in the curable composition or the refractive index of the cured diffraction light guide plate is lowered, and if it is too small, there is a problem in that the curing reaction rate cannot be controlled. .

In addition, the photocurable composition may further include a catalyst. The catalyst is not particularly limited as long as it plays a role in accelerating the curing reaction of the curable composition. For example, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimida Sol, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, etc. Imidazole derivatives of; Dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethyl benzylamine, 4-methoxy-N,N-dimethylbenzylamine, 4-methyl-N,N-dimethylbenzylamine, N, Amine compounds such as N-dicyclohexylmethylamine; Hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; And phosphorus compounds such as triphenylphosphine. In addition, as commercially available ones, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ manufactured by Shikoku Kasei Kogyo (all are brand names of imidazole compounds), U-CAT3503N, UCAT3502T manufactured by San Apro (All are trade names of dimethylamine block isocyanate compounds), DBU, DBN, U-CATSA102, and U-CAT5002 (all bicyclic amidine compounds and salts thereof), and the like.

The content of the catalyst may be 0.001 to 10% by weight, 0.01 to 5% by weight, or 0.1 to 1% by weight, based on 100% by weight of the total curable composition. If the content of the catalyst is too high, the curing reaction proceeds rapidly, and there is a problem in handling the curable composition due to overheating, and long-term storage is difficult and streaking may occur. On the other hand, if the content of the catalyst is too small, the optical and mechanical properties of the cured diffraction light guide plate may be deteriorated due to uncured.

In addition, the curable composition may further include other additives used to impart a specific function to a display substrate in the technical field to which the present invention pertains, in addition to this, a UV absorber, a bluing agent, and a pigment.

The photocurable composition may be a photocurable composition or a thermosetting composition. Specifically, the curable composition may be a thermosetting composition.

Meanwhile, the curable composition may have a curing shrinkage of 15% or less, 1% to 15% or less, 1% or more and 12% or less, or 1% or more and 10% or less, but is not limited thereto.

In addition, the curable composition may be stored for a long time, and in particular, it may be stored for a long time even in a state in which a catalyst is included. In addition, it is possible to suppress the streak phenomenon caused by rapid hardening. Specifically, the curable composition has a viscosity of 4000 cP or less, 3000 cP or less, 2500 cP or less, 2000 cP or less, 1000 cP or less, 500 cP or less, 300 cP or less, after being maintained at a temperature of -5 to 0°C for 12 hours, It may be 100 to 200 cP.

The method of manufacturing a light guide plate according to the other embodiment may include compressing the curable composition under a load of the flat upper substrate, and curing the curable composition.

2 is a diagram schematically showing a cross section of a mold equipment in a step of curing a curable composition. Specifically, FIG. 2 is a diagram of a molding equipment including a buffer type spacer 503 provided between a planar lower substrate 501 and a flat upper substrate 502 including a template 504 in which a diffraction grating pattern is engraved. It shows that the curable composition 600 is injected into the molding space to be buffered. In this way, after the curable composition is buffered, photocuring and/or thermosetting may be performed to prepare a diffractive light guide plate.

In order to heat-cure the curable composition, the heating rate of the curable composition may be 2 °C/min or less, 1 °C/min or less, or 0.1 to 0.5 °C/min. When the heating rate is within the above range, it is possible to induce uniform curing of the curable composition by minimizing the variation between positions of heat transferred to the curable composition and minimizing the unevenness of discharge of reaction heat.

During the thermal curing, the final temperature may be 50 to 100° C., or 60 to 80° C., and between positions of heat transferred to the curable composition by placing an isothermal maintenance section three or more times at a temperature lower than the final temperature before reaching the final temperature. The deviation can be minimized. The temperature difference between the isothermal maintenance periods may be 10°C to 20°C, and the holding time of the isothermal maintenance periods may be 1 hour to 5 hours, respectively. For example, after allowing the curable composition to stand at room temperature (25°C) for 2 hours, heat curing at 45°C for 2 hours, 60°C for 2 hours, 75°C for 2 hours, and 90°C for 4 hours to obtain a diffraction light guide plate. Can be manufactured.

In the step of curing the curable composition, a diffraction grating pattern may be formed on one surface of the optical layer by a template in which the diffraction grating pattern is engraved. The diffraction grating pattern is the same as the description of the diffraction grating pattern formed on one surface of the optical layer included in the aforementioned diffraction light guide plate.

The flexural modulus of the flat lower substrate and the flat upper substrate may be 3 GPa or more, 10 GPa or more, 20 GPa or more, or 40 GPa to 300 GPa, respectively. When the flexural modulus of the flat lower substrate and the flat upper substrate is within the above range, the bowing phenomenon of the flat upper substrate can be minimized, and thus the thickness uniformity of the manufactured diffractive light guide plate can be greatly increased. .

The flexural modulus of the template in which the diffraction grating pattern is engraved may be 1 to 20 GPa, 1.5 to 15 GPa, or 2 to 10 GPa. If the flexural modulus of the template in which the diffraction grating pattern is engraved is less than 1 GPa, the uniformity of the diffraction grating pattern may be damaged as the curable composition is cured and contracted, and if it exceeds 20 GPa, the diffraction grating pattern engraved on the template due to excessive stiffness. This can be damaged.

Surface flatness of the flat lower substrate and the flat upper substrate may be 5 μm or less, 2 μm or less, or 0.01 to 1 μm, respectively. When the surface flatness of the flat lower substrate and the flat upper substrate is within the above range, the surface flatness of the manufactured diffractive light guide plate may be significantly improved than that of a general diffractive light guide plate.

The method of measuring the surface flatness is as follows. Specifically, in an atmosphere of 25° C. and 50 RH%, measure one point per 0.16 Х 0.16 mm 2 in a 200 mm diameter area with QED's ASI (aspheric stitching interferometry) equipment, or use a three-dimensional shape measuring instrument of Deokin, It can be measured as a value obtained as the difference between the highest and lowest values of the height measured at intervals of 5 mm and 11.25 degrees with a radius of 5 mm based on an arbitrary origin in a 200 mm diameter region.

Each of the planar lower substrate and the planar upper substrate may be a transparent substrate. Specifically, the planar lower substrate and the planar upper substrate may each be an organic substrate, which may effectively perform photocuring of the curable composition due to excellent light transmission properties.

The compressive elastic modulus of the buffer spacer may be 0.1 MPa to 10 MPa, 0.1 MPa to 5 MPa, 0.1 MPa to 3 MPa, or 0.1 MPa to 2 MPa. When the compressive elastic modulus of the buffer-type spacer is within the above range, a load is uniformly transferred to the curable composition when the flat upper substrate is in contact, thereby increasing the thickness uniformity of the diffraction light guide plate, and diffraction engraved on the template. The grating pattern may clearly appear as a diffraction grating pattern on one side of the cured product.

A method of measuring the compressive elastic modulus of the buffer spacer is as follows. In an atmosphere of 25 ℃ and 50 RH%, specimen deformation of the force measured when compression with a specimen area of 5 Х 5 ㎟ and a compression speed of 1 mm/min using TA's Texture Analyzer ((initial thickness-thickness after deformation)/initial It may mean a slope for thickness). In addition, when the buffer spacer is composed of two or more different layers, the compressive modulus of the buffer spacer is the force measured when the laminated specimen is prepared with an area of 5 Х 5 mm2 and compressed at a compression speed of 1 mm/min. It may be a measure of the slope for deformation ((initial thickness-thickness after deformation)/initial thickness).

The buffer spacer may have a structure in which an inelastic layer and an elastic layer are stacked, a structure in which an elastic layer is provided between the inelastic layers, or a structure in which an inelastic layer is provided between the elastic layers. Meanwhile, when the buffer spacer has a structure in which an inelastic layer and an elastic layer are stacked, an elastic layer is provided between the inelastic layers, or a structure in which the inelastic layer is provided between the elastic layers, the compressive elastic modulus of the buffer spacer is It may mean the compressive elastic modulus of the elastic layer.

Since the buffer spacer may be designed in consideration of the degree of shrinkage of the curable composition, it may serve as a support as the inelastic layer, and may serve as the elastic layer to control a height change according to the shrinkage of the curable composition. have.

The curing shrinkage rate of the curable composition may be 15% or less, 1% to 15%, 1% to 12%, or 1% to 10%.

The curing shrinkage rate of the curable composition may be derived as shown in General Formula 3 below.

[General Formula 3]

Curing shrinkage (%) = {(volume before curing-volume after complete curing) / volume before curing} Х 100.

The method of manufacturing a diffractive light guide plate according to another embodiment may further include obtaining a diffractive light guide plate from the mold equipment. Specifically, in the step of obtaining the diffractive light guide plate, a diffractive light guide plate may be obtained by removing the flat upper substrate, the flat lower substrate, and the template in which the diffraction grating pattern is engraved. Removing the planar upper substrate, the planar lower substrate, and the template may include, after the curing of the curable composition is completed, the planar upper substrate, the flat lower substrate, and the template are transferred to a diffractive light guide plate that is a cured product of the curable composition. It can mean separating.

The description of physical properties such as thickness and thickness deviation, refractive index, glass transition temperature, haze, and the like of the diffractive light guide plate manufactured by the method of manufacturing the diffractive light guide plate according to the other embodiment are as mentioned in the above-described diffraction light guide plate. In addition, as mentioned above, the diffractive light guide plate may be for a diffractive light guide lens of a wearable device.

On the other hand, the thickness of the diffractive light guide plate may be adjusted according to the separation distance between the flat lower substrate and the flat upper substrate and the curing shrinkage rate of the curable composition, and the diffractive light guide plate within the above range according to the use of the diffractive light guide plate. The thickness can be adjusted.

Surfaces of the flat lower substrate, the flat upper substrate, and the template in which the diffraction grating pattern is engraved may be surface-treated with a release agent, respectively. The release agent may be applied without limitation, provided it is generally used in the art. For example, the surface treatment with the release agent may be surface coated with a fluorine-based silane coupling agent. When the surface is coated using the release agent, in the step of obtaining the diffractive light guide plate, damage to the surface of the diffractive light guide plate is minimized, and the flat lower substrate, the flat upper substrate, and the template can be removed.

According to the present invention, it is possible to provide a diffractive light guide plate having excellent thickness uniformity and flatness, low haze, excellent mechanical properties such as pencil hardness and strength, and capable of implementing a high refractive index while being lighter than glass or tempered glass. In addition, it is possible to provide a method of manufacturing a diffractive light guide plate capable of manufacturing such a diffractive light guide plate by a simple one-step process.

1 is a schematic cross-sectional view of an optical layer included in a diffractive light guide plate according to an embodiment of the present invention.
2 is a view schematically showing a cross section of a mold equipment in the step of curing a curable composition in a method of manufacturing a diffractive light guide plate according to another embodiment of the present invention.

The invention will be described in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

Preparation Example 1: Preparation of curable composition

89.0 parts by weight of bis(β-epithiopropyl)sulfide, 7.0 parts by weight of 2,2'-thiodiethanethiol, 3.0 parts by weight of 2.2'-dihydroxy-1,1'-binaphthalene, and N,N as a catalyst -To prepare a curable composition containing 1.0 part by weight of dicyclohexylmethylamine.

The curing shrinkage force of the prepared curable composition was measured by the method of measuring the curing shrinkage force described above, and the compressive stress coefficient calculated by dividing the measured curing shrinkage force by the volume of the sample was 2.5*10 ³ N/m ³ .

Preparation Example 2: Preparation of curable composition

A curable composition comprising 89.5 parts by weight of bis(β-epithiopropyl)sulfide, 9.5 parts by weight of 2,2'-thiodiethanethiol, and 1.0 parts by weight of N,N-dicyclohexylmethylamine as a catalyst was prepared.

The curing shrinkage force of the prepared curable composition was measured by the method of measuring the curing shrinkage force described above, and the compressive stress coefficient calculated by dividing the measured curing shrinkage force by the volume of the sample was 2.5*10 ³ N/m ³ .

Preparation Example 3: Preparation of imprint resin composition

8.3 parts by weight of zirconia particles having a particle diameter of 20 nm, 8.3 parts by weight of dipentaerythritol hexaacrylate (DPHA), 83.0 parts by weight of butyl carbitol acetate, and 0.4 parts by weight of ethyl (2,4,6-trimethylbinzoyl) phenylphosphinate An imprint resin composition containing was prepared.

<Examples and Comparative Examples: Preparation of diffractive light guide plate>

Example 1

As a lower substrate, a glass substrate having a flexural modulus of 70 GPa, a surface flatness of 0.5 μm, a thickness of 30 mm, and a diameter of 200 mm was prepared, and a template (flexural modulus: 3 GPa) in which a diffraction grating pattern was engraved on the lower substrate was prepared. Attached. At this time, it was attached so that the circular center of the lower substrate and the circular center of the template were in contact, the diameter of the template was 150 mm, the thickness was polyethylene terephthalate (PET), and the pitch of the engraved diffraction grating pattern was It was 405 nm and the depth was 500 nm.

Thereafter, a buffer-type spacer made of silicon having a compressive elastic modulus of 1.0 MPa, a height of 1,007 µm, and a cross-sectional area of 10 Х 10 ㎟ is provided at 120° intervals to contact the circumference of the lower substrate to form a molding space. After injecting the curable composition prepared according to Preparation Example 1 into the molding space, the curable composition using a glass substrate having a flexural modulus of 70 GPa, a load of 8.2 N, a diameter of 200 mm, and a surface flatness of 0.5 μm as an upper substrate Was buffered in the molding space.

Further, the curable composition was placed in a convection oven of Jeio Tech, allowed to stand at room temperature for 2 hours, and then the heating rate was set to 1° C./min, followed by 2 hours at 45° C., 2 hours at 60° C., 2 hours at 75° C. , Heat curing at 90° C. for 4 hours to prepare a diffractive light guide plate having a thickness of 0.8 mm.

Comparative Example 1

A diffractive light guide plate was manufactured in the same manner as in Example 1, except that the curable composition prepared according to Preparation Example 2 was used instead of the curable composition prepared according to Preparation Example 1.

Comparative Example 2

As the lower substrate, a glass substrate with a flexural modulus of 70 GPa, a surface flatness of 0.5 µm, a thickness of 30 ㎜, and a diameter of 200 ㎜ was used, and a compressive elastic modulus of 1.0 MPa, a height of 804 µm, and a cross-sectional area of 10 Х 10 ㎟. After forming a molding space by providing a silicone buffer spacer at 120° intervals to contact the circumference of the lower substrate, the curable composition prepared according to Preparation Example 1 was injected into the molding space, and then bent as an upper substrate. The curable composition was buffered in the molding space using a glass substrate having an elastic modulus of 70 GPa, a load of 8.2 N, a diameter of 200 mm, and a surface flatness of 0.5 µm.

Further, the curable composition was placed in a convection oven of Jeio Tech, allowed to stand at room temperature for 2 hours, and then the heating rate was set to 1 °C/min, followed by 2 hours at 45 °C, 2 hours at 60 °C, 2 hours at 75 °C. , By heat curing at 90° C. for 4 hours to prepare a plastic substrate.

The imprint resin composition (refractive index 1.70) prepared according to Preparation Example 3 was applied to the plastic substrate and then dried to form an imprint resin layer having a thickness of 1 μm. Thereafter, a template (diameter 150 mm, thickness 200 µm, polyethylene terephthalate) in which a diffraction grating pattern having a pitch of 405 nm and a depth of 1 µm was engraved on the imprint resin layer was applied at a temperature of 40° C. and a pressure of 20 bar. After forming a diffraction grating by pressing at, the diffraction light guide plate having a thickness of 0.8 mm was prepared by irradiation with UV (360 nm light source) of ^{1000 mJ/cm 2 and cured, and cut into a rectangular shape of 6 占5 cm.}

Comparative Example 3

A diffractive light guide plate was manufactured in the same manner as in Comparative Example 2, except that the curable composition prepared according to Preparation Example 2 was used instead of the curable composition prepared according to Preparation Example 1.

evaluation

1. Refractive index measurement

The refractive indexes of the diffractive light guide plates of Examples and Comparative Examples were measured using spectroscopic ellipsometry of Ellipso Technology, and the results are shown in Table 1 below.

2. Haze measurement

The haze of the diffractive light guide plates of Examples and Comparative Examples was measured by ASTM D-1003, and the results are shown in Table 1 below.

3. Pencil hardness measurement

After fixing the pencil to the surface of the diffraction light guide plate of Examples and Comparative Examples at a load of 0.5 kg and an angle of 45°, it was determined whether or not the pencil was scratched with the naked eye by scratching according to the pencil hardness, and the maximum pencil hardness without scratches is shown in Table 1 below .

4. Warp measurement

For the diffraction light guide plates of Examples and Comparative Examples, specimens having a rectangular area of 600 mm long and 400 mm short were prepared, and warp was calculated through the following General Formula 2, and the results are shown in Table 1 below.

[General Formula 2]

Warp = maximum deviation between center plane and reference plane-minimum deviation between center plane and reference plane

The central surface is a reference optical body installed under the diffractive light guide plate and the thickness of the diffractive light guide plate using a non-contact measurement method using OWTM (Optical Wafer Thickness Measurement System) equipment of Fiber Pro in an atmosphere of 25° C. and 50 RH% It can be derived by measuring the distance between and the diffraction light guide plate. Meanwhile, the reference plane may be calculated using a least squares fit with respect to the center plane.

5. Glass transition temperature measurement measurement

The glass transition temperature (Tg) was measured using Perkin Elmer's Pyris 6 DSC (Differential Scanning Calorimetry) for the diffracted light guide plates of Examples 1 and 2 and the plastic substrates of Comparative Examples 2 and 3, and the results are shown in Table 1 below. Indicated.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Refractive index 1.73 1.71 1.73 1.71 Haze (%) 1.4 1.4 4.1 4.2 Pencil hardness 2H 2H 6B 6B Warp (㎛) 20 24 55 68 Glass transition temperature (℃) 85 74 85 74

According to Table 1 below, a diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer, and has a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups. It was confirmed that the diffractive light guide plate of Example 1 had high refractive index and glass transition temperature, excellent pencil hardness, low warp and low haze, and high visibility.

On the other hand, it was confirmed that Comparative Example 1 not using the aromatic heterocyclic compound had a lower refractive index and glass transition temperature and higher warp than that of Example 1. In addition, it was confirmed that in Comparative Examples 2 and 3, in which the interface between the diffraction grating pattern and the optical layer was present, warp and haze were significantly higher than in Example 1, and the pencil hardness was lowered.

200: diffraction grating pattern 300: optical layer
400: pattern unit 501: flat bottom substrate
502: flat upper substrate 503: buffer type spacer
504: template in which the diffraction grating pattern was engraved 600: curable composition

Claims (19)

Including an optical layer formed on one surface of the diffraction grating pattern,
The diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer,
The difference in refractive index between the diffraction grating pattern and one surface of the optical layer is 0.01 or less,
The optical layer on which the diffraction grating pattern is formed is a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups.
The method of claim 1,
The diffraction grating pattern and one surface of the optical layer each have a refractive index of 1.65 or more.
The method of claim 1,
The weight ratio of the thiol compound and the aromatic ring compound having two or more hydroxyl groups is 5:5 to 9:1, the diffraction light guide plate.
The method of claim 1,
The episulfide compound includes a compound represented by Formula 1 below,
The thiol compound includes at least one selected from compounds represented by the following formulas 2 and 3,
The aromatic ring compound having two or more hydroxyl groups comprises at least one selected from compounds represented by the following Formulas 4 and 5, a diffraction light guide plate:
[Formula 1]

In Formula 1,
R ₁ and R ₂ are each independently hydrogen or alkyl having 1 to 10 carbon atoms,
R ₃ and R ₄ are each independently a single bond or an alkylene having 1 to 10 carbon atoms,
a is an integer from 0 to 4,
b is an integer from 0 to 6,
[Formula 2]

In Chemical Formula 2,
R ₅ and R ₆ are each independently a single bond or an alkylene having 1 to 10 carbon atoms,
c is an integer from 0 to 4,
d is an integer from 0 to 6,
[Formula 3]

In Chemical Formula 3,
Ring A is a 5-membered or 6-membered aromatic hetero ring containing at least one of nitrogen (N) and sulfur (S) atoms,
e is an integer from 1 to 3,
[Formula 4]

In Chemical Formula 4,
R ₇ and R ₈ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, and 1 to 40 carbon atoms. Alkenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S,
f and g are each independently an integer of 1 to 7,
h and i are each independently an integer of 0 to 6,
f+h is an integer of 7 or less,
g+i is an integer of 7 or less,
[Formula 5]

In Chemical Formula 5,
Ar ₁ and Ar ₂ are each independently an aryl having 6 to 60 carbon atoms in which one or more hydroxyl groups are substituted,
R ₉ and R ₁₀ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, and having 1 to 40 carbon atoms. Alkenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S,
m and n are each independently an integer of 0 to 4.
The method of claim 1,
The diffractive light guide plate has a thickness of 0.1 to 10 mm.
The method of claim 1,
The diffraction grating pattern includes one or more pattern units,
A diffraction light guide plate having a pitch between the pattern units of 0.1 to 1 μm and a height of 0.1 to 1 μm.
The method of claim 1,
The warp of the diffractive light guide plate is 100 μm or less,
The haze of the diffractive light guide plate is 4.0% or less,
The pencil hardness of the diffractive light guide plate is HB or higher,
The diffractive light guide plate has a thickness deviation of 3.0% or less.
The method of claim 1,
The transmittance of the diffractive light guide plate is 80% or more,
The diffractive light guide plate has a yellow index (YI) of 1 to 30.
The method of claim 1,
The diffractive light guide plate is for a diffractive light guide lens of a wearable device.
A template in which a diffraction grating pattern included in the flat lower substrate, the flat upper substrate, the buffer spacer positioned between the flat lower substrate and the flat upper substrate, and the flat lower substrate or the flat upper substrate is engraved preparing a mold equipment including a (template) and in which a molding space is partitioned by the buffer spacer;
Buffering the curable composition in the molding space; And
Compressing the curable composition under the load of the flat upper substrate and curing the curable composition; Including,
The curable composition includes an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups,
Compressing the curable composition under the load of the flat upper substrate, and curing the curable composition is performed to satisfy Equation 1 below:
[Equation 1]
{(Load of flat upper substrate + curing contraction force of curable composition) Х 0.95} ≤ Compressive stress of buffer spacer ≤ {(load of flat upper substrate + curing contraction force of curable composition) Х 1.05}.
The method of claim 10,
The method of manufacturing a diffractive light guide plate, wherein the flat lower substrate and the flat upper substrate each have a flexural modulus of 3 GPa or more.
The method of claim 10,
The template in which the diffraction grating pattern is engraved has a flexural modulus of 1 to 20 GPa.
The method of claim 10,
A method of manufacturing a diffractive light guide plate, wherein the flatness of the surface of the flat lower substrate and the upper flat substrate is 5 μm or less.
The method of claim 10,
The compressive elastic modulus of the buffer spacer is 0.1 to 10 MPa, the method of manufacturing a diffractive light guide plate.
The method of claim 10,
The buffer spacer is a structure in which an inelastic layer and an elastic layer are stacked, an elastic layer is provided between the inelastic layers, or an inelastic layer is provided between the elastic layers.
The method of claim 10,
The weight ratio of the thiol compound and the aromatic ring compound having two or more hydroxyl groups is 5:5 to 9:1, the diffraction light guide plate manufacturing method.
The method of claim 10,
The episulfide compound includes a compound represented by Formula 1 below,
The thiol compound includes at least one selected from compounds represented by the following formulas 2 and 3,
The aromatic ring compound having two or more hydroxyl groups comprises at least one selected from compounds represented by the following Formulas 4 and 5, a method of manufacturing a diffraction light guide plate:
[Formula 1]

In Formula 1,
R ₁ and R ₂ are each independently hydrogen or alkyl having 1 to 10 carbon atoms,
R ₃ and R ₄ are each independently a single bond or an alkylene having 1 to 10 carbon atoms,
a is an integer from 0 to 4,
b is an integer from 0 to 6,
[Formula 2]

In Chemical Formula 2,
R ₅ and R ₆ are each independently a single bond or an alkylene having 1 to 10 carbon atoms,
c is an integer from 0 to 4,
d is an integer from 0 to 6,
[Formula 3]

In Chemical Formula 3,
Ring A is a 5-membered or 6-membered aromatic hetero ring containing at least one of nitrogen (N) and sulfur (S) atoms,
e is an integer from 1 to 3,
[Formula 4]

In Chemical Formula 4,
R ₇ and R ₈ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, and 1 to 40 carbon atoms. Alkenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S,
f and g are each independently an integer of 1 to 7,
h and i are each independently an integer of 0 to 6,
f+h is an integer of 7 or less,
g+i is an integer of 7 or less,
[Formula 5]

In Chemical Formula 5,
Ar ₁ and Ar ₂ are each independently aryl having 6 to 60 carbon atoms substituted with one or more hydroxyl groups,
R ₉ and R ₁₀ are each independently deuterium, halogen, cyano, nitrile, nitro, amino, alkyl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, and eggs having 1 to 40 carbon atoms. Kenyl, aryl having 6 to 60 carbon atoms, or heteroaryl having 1 to 40 carbon atoms including at least one of O, N, Si and S,
m and n are each independently an integer of 0 to 4.
The method of claim 10,
The curing shrinkage ratio of the curable composition is 15% or less, the diffractive light guide plate manufacturing method.
The method of claim 10,
The curable composition has a viscosity of 4000 cP or less after being maintained at a temperature of -5 to 0° C. for 12 hours, a method of manufacturing a diffractive light guide plate.

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