KR102456679B1 - Diffraction light guide plate and manufacturing method thereof the same - Google Patents

Abstract

The present invention relates to a diffractive light guide plate having excellent thickness uniformity and flatness, low haze, excellent visibility, and excellent mechanical properties such as pencil hardness and strength, and a method of manufacturing such a diffractive light guide plate.

Description

Diffraction light guide plate and manufacturing method of diffractive light guide plate

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

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

A virtual reality device or an augmented reality device may form a diffraction light guide pattern on a lens 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 broken, it may cause fatal damage to the user's eye. It has a high density and is heavy, so it is uncomfortable to wear for a long time.

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

In the case of high-refractive plastic to replace glass, it is very light and various colors can be realized, but there is a problem in that physical properties such as surface flatness and thickness uniformity do not significantly reach that of conventional glass.

Furthermore, in the imprint process of forming the diffraction grating, shape deformation occurs due to low strength, or when a large amount of inorganic particles are used to realize high refractive index, it not only causes haze of the final product, but also the interfacial 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, light compared to glass or tempered glass, and capable of realizing a high refractive index.

Another object of the present invention is to provide a method for manufacturing a diffractive light guide plate for manufacturing the diffractive light guide plate through a simple process.

In the present specification, the diffraction grating pattern includes an optical layer 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 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 formed on one surface of the diffraction grating pattern is a diffraction light guide plate that 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.

In addition, in the present specification, a flat lower substrate, a flat upper substrate, a buffer spacer positioned between the flat lower substrate and the flat upper substrate, and diffraction included in the flat lower substrate or the flat upper substrate Preparing a mold equipment comprising a lattice pattern engraved template (template), the molding space is partitioned by the cushioning spacer; buffering a 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 two or more hydroxyl groups. There is provided a method for manufacturing a diffractive light guide plate comprising: compressing the curable composition under a load of the flat upper substrate, and curing the curable composition is performed to satisfy Equation 1 below.

[Equation 1]

{(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 0.95} ≤ Compressive stress of the cushioning spacer ≤ {(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 1.05}.

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

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

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

In addition, the term "step of" or "step of" to the extent used does not mean "step for".

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

As used herein, the definition of 'thiol compound' refers to a compound containing one or more thiol groups (-SH).

As used herein, the term 'curing' includes both thermosetting and photocuring, and 'curable composition' refers to a thermosetting and/or photocurable composition.

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

According to one embodiment of the invention, the diffraction grating pattern includes an optical layer formed on one surface, the diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer, the diffraction grating pattern and the optical layer The difference in refractive index between the surfaces is 0.01 or less, and the optical layer on which the diffraction grating pattern 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, a diffraction light guide plate may be provided have.

In the optical layer on 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 the continuous phase of the polymer containing it, mechanical properties such as pencil hardness and strength of the diffractive light guide plate are excellent. In addition, there is almost no difference in refractive index between the diffraction grating pattern and one surface of the optical layer, so there is no problem of a decrease in transmittance or haze occurring at the interface, as well as a problem of light incident on the diffraction light guide plate (that is, a light guide )), the efficiency of total reflection within the diffraction light guide plate is increased, and when used in a virtual reality device, a high-resolution image with higher luminance can be displayed.

In the case of a conventional diffraction light guide plate, a resin composition for imprinting is applied on a substrate and dried to form a resin layer, and then a template having a diffraction grating pattern engraved on the resin layer is imprinted through a process of imprinting a pattern portion. Although the light guide plate was manufactured, in the diffractive light guide plate manufactured in this way, an interface exists between the substrate and the pattern part, and it was difficult to secure mechanical properties such as pencil hardness due to poor interfacial adhesion. However, in the diffraction light guide plate according to the exemplary embodiment, the diffraction grating pattern is formed in an integrated structure without an interface on one surface of the optical layer, thereby exhibiting excellent mechanical properties such as high pencil hardness and strength.

In addition, the optical layer formed on one surface of the diffraction grating pattern included in the diffraction light guide plate 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 has a high refractive index and can be used as a diffractive light guide lens for wearable devices. For this reason, it is possible to prevent problems caused by breakage of the conventional glass and difficult to wear for a long time due to the heavy weight of the glass. Furthermore, the diffractive light guide plate can realize a high refractive index even if it does not additionally include inorganic particles, so that it does not cause haze due to inorganic particles and has a low haze, so that visibility is high. In addition, the diffractive light guide plate may be manufactured by a method of manufacturing the diffractive light guide plate to be described later, and thus may have excellent thickness uniformity and flatness.

Since the optical layer on which the diffraction grating pattern 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, 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. When the difference in refractive index between the diffraction grating pattern and the one surface of the optical layer exceeds 0.01, a problem of a decrease in transmittance resulting from an interface between the diffraction grating pattern and one surface of the optical layer may occur or haze. Accordingly, since the difference in refractive index between the diffraction grating pattern and the one surface of the optical layer satisfies the above range, there is no problem of a decrease in transmittance or haze occurring at the interface, and total reflection of light guided When the efficiency is increased and used in a virtual reality device, an image with higher luminance can be displayed.

1 is a diagram schematically illustrating a cross-section of an optical layer included in the diffractive light guide plate according to the exemplary embodiment. Specifically, the optical layer 300 may have a diffraction grating pattern 200 formed on one surface, and the diffraction grating pattern may include one or more pattern unit 400 .

Specifically, the diffraction grating pattern 200 may include two or more pattern unit bodies 400 spaced apart from one side in the direction of the other side. The pattern unit is not particularly limited as long as it is a pattern capable of diffraction of waveguided light, but is a lattice pattern having the form of a quadrangular prism, a hexagonal prism, a triangular pyramid, a cone, an elliptical cone, or a hemisphere, or a bar or stripe pattern can Meanwhile, the shape of the cross-section of the pattern unit body is not particularly limited, but may have, for example, a quadrangle, a triangle, a rhombus, a trapezoid, a parabola, and the like. The direction of the cross-section of the pattern unit may be perpendicular to the diffraction light guide plate.

In addition, a pitch between the pattern unit bodies 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 is 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, it may mean a length between one point of one pattern unit and one point of another adjacent pattern unit. Also, 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 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 unit bodies 400 included in the diffraction grating pattern 200 are included, the shapes of the two or more pattern unit bodies may be the same, and specifically, the cross-sectional shape, period, height, etc. may be the same. have. Accordingly, the amount of light diffracted in the entire region of the diffractive light guide plate may be the same. In addition, the shape of the two or more pattern unit 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 is 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. When the thickness of the optical layer 300 is too thin, the number of times that the light incident on the diffractive light guide plate including the optical layer is unnecessarily totally reflected inside the diffraction light guide plate increases, thereby increasing the luminance of the light emitted from the diffraction light guide plate. Therefore, when such a diffractive light guide plate is used in a virtual reality device or the like, the resolution may be reduced. On the other hand, when the thickness of the optical layer is too thick, the transmittance of external light with respect to the diffractive light guide plate including the optical layer is reduced, so that the luminance of the external image is lowered, and thus visibility may be deteriorated.

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

In the diffraction light guide plate, an optical layer having the diffraction grating pattern formed on one surface is formed in a one-step process by a method for manufacturing the diffraction light guide plate to be described later, and the diffraction grating pattern is integrated on one surface of the optical layer without an interface. 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 on one surface corresponds to a continuous phase of a polymer including an episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups. In addition, the continuous phase of the polymer can realize a high refractive index without including inorganic particles, thereby preventing haze-induced problems that occur 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 ring compound having two or more hydroxyl groups is less than 5:5, it may be difficult to implement a high refractive index of the diffractive light guide plate, and if it exceeds 9:1, the curing rate control during curing of the curable composition including them is It becomes difficult, and there is a problem in that a streaking 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 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 Chemical Formula 1 has an aliphatic chain skeleton in which episulfide is connected to both ends of the molecule, and in the aliphatic chain, an alkylene group is connected by a sulfur (S) atom. ether) in the form of 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 high content of sulfur atoms may increase the refractive index of the diffraction light guide plate. In addition, 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 diffractive light guide plate.

Meanwhile, in Formula 1, R ₁ and R ₂ may each independently be hydrogen or a methyl group, but is 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 is 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 in the alkylene group included in the thioether repeating unit. When a is too large, the length of the carbon chain in the molecule becomes long, and the glass transition temperature of the diffraction light guide plate is lowered. , this may cause a problem in that the heat resistance of the diffractive light guide plate is lowered, and also, the relative sulfur content is lowered and thus the refractive index of the diffractive light guide plate is lowered.

b in Formula 1 is the number of repeating thioether repeating units in which an alkylene group is connected by a sulfur (S) atom. of the glass transition temperature is lowered, which may cause a problem in that the heat resistance of the diffractive light guide plate is lowered.

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

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

The content of the episulfide compound may be 50 to 99 wt%, 60 to 95 wt%, or 70 to 90 wt% based on 100 wt% 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 diffractive light guide plate is lowered and the yellow index (YI) is increased. On the other hand, if the content of the episulfide compound is too small, the glass transition temperature of the diffractive 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 the following Chemical Formulas 2 and 3.

[Formula 2]

In Formula 2,

R ₅ and R ₆ are each independently a single bond or 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 Formula 3,

Ring A is a 5-membered or 6-membered aromatic heterocyclic 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 skeleton in which thiol groups (-SH) are linked to both ends of the molecule, and in the aliphatic chain, the alkylene group is formed by a sulfur (S) atom. It may include a repeating unit in the form of a linked thioether (thio ether).

Meanwhile, in the thiol compound represented by Formula 3, one or more thiol groups may be connected to a 5- or 6-membered aromatic ring including 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 in a curing reaction with the episulfide compound, that is, a ring-opening polymerization reaction of the episulfide group, to form a disulfide bond, etc., and atoms in the molecule The refractive index of the diffractive light guide plate may be further increased by including high refractive sulfur (S) atoms in a high content, 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 represent a single bond, methylene, ethylene, propylene, isopropylene, butylene, or isobutylene, but is 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 included in the thioether repeating unit. When c is too large, the length of the carbon chain in the molecule becomes long, so that 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 may occur because the relative sulfur content is lowered.

d in Formula 2 is the number of repeating thioether repeating units in which an alkylene group is connected by a sulfur (S) atom. The transition temperature is lowered, and accordingly, there may be a problem in that the heat resistance of the diffractive light guide plate is lowered.

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

Also, e may be 2 or 3.

In addition, the compound represented by the 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. When the content of the thiol compound is too large, there may be problems in that the glass transition temperature of the diffractive light guide plate is lowered, the yellow index (YI) is increased, and physical properties such as hardness and strength are lowered. On the other hand, when the content of the thiol compound is too small, there is a problem in that the glass transition temperature of the diffractive light guide plate is lowered and the yellow index (YI) is increased.

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

[Formula 4]

In 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, cycloalkyl 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;

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 Formula 5,

Ar ₁ and Ar ₂ are each independently an 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, cycloalkyl 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 ring compound having two or more hydroxyl groups represented by Chemical Formula 4 has a skeleton in which two naphthalenes are connected, and one or more hydroxyl groups may be connected to each naphthalene.

On the other hand, the aromatic ring compound having two or more hydroxyl groups represented by Chemical Formula 5 may represent a form in which two aryl groups in which one or more hydroxyl groups are substituted at the 9th position of fluorene are substituted.

The aromatic ring compound having two or more hydroxyl groups represented by Formula 4 or 5 may implement a high refractive index of the diffractive light guide plate by a conjugation system of aromatic functional groups, and also, due to these aromatic functional groups, diffraction As the aromatic ring compound is included in the light guide plate, even if the content of sulfur atoms is reduced, a decrease in refractive index may be minimized, and further, mechanical properties may be improved by increasing the glass transition temperature (Tg) of the diffractive light guide plate.

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

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

Also, 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 one or two hydroxyl groups, but is not limited thereto.

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

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

In addition, the compound represented by the 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 ring 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 ring compound having two or more hydroxyl groups is too large, the refractive index of the diffractive light guide plate is lowered.

In addition, the continuous phase of the polymer may further include a catalyst. The catalyst includes, for example, an amine, an ammonium salt, or a phosphate salt, 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; Phosphorus compounds, such as a triphenylphosphine, etc. are mentioned. In addition, as a commercially available thing, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (all are the brand names of an imidazole type compound) by Shikoku Kasei Kogyo Co., Ltd., U-CAT3503N, UCAT3502T by San Apro, for example. (all are brand names of the block isocyanate compound of dimethylamine), DBU, DBN, U-CATSA102, U-CAT5002 (all are bicyclic amidine compounds and its salt), etc. are mentioned.

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, such as an ultraviolet absorber, a bluing agent, and a pigment.

The continuous phase of the polymer may be a photocured material or a thermoset material.

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 optical refractive 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 substituted for the glass substrate because the light refractive index equal to that of the glass substrate may be realized despite the plastic material. In addition, when used as a lens of a wearable device due to a high refractive index, optical loss can be minimized and optical information can be moved.

In addition, the glass transition temperature of the diffractive 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 proceed, and accordingly, the temperature of the lens may increase. Meanwhile, since the diffraction light guide plate may have a glass transition temperature of 40° C. or higher, even when used as a lens of a wearable device, a change in physical properties according to temperature can be minimized to realize 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 more 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 more, H or more, or 2H or more. 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.

Also, although the diffractive light guide plate includes one or more pattern units, the thickness deviation may be 3.0% or less, 2.5% or less, 1% or less, or 0.1 to 1%. Since the thickness uniformity of the diffractive light guide plate is higher as the value of the thickness deviation is lower, the diffractive light guide plate according to the exemplary embodiment may have excellent thickness uniformity.

In addition, the thickness deviation of the diffractive light guide plate may be derived by the following general formula (1).

[General formula 1]

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

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

On the other hand, the average thickness is at 25 ℃ and 50 RH% atmosphere, using the contact measurement method using Mitsutoyo's Digimatic Thick 547-401 equipment, at any point of the randomly placed specimen as the origin, with a radius of 10 mm and 22.5 degrees. It may be an average value of thicknesses 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, any point of the randomly placed specimen as the origin, horizontal and vertical It may be an average value of the thicknesses measured at intervals of 1 mm for each.

A 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 for manufacturing the diffractive light guide plate according to the exemplary embodiment may satisfy the warp range, and when the warp of the diffractive light guide plate exceeds 100 μm, the reflection angle of the light incident on the diffractive light guide plate cannot be maintained, which can be achieved in virtual reality. When used for devices, etc., the resolution may be reduced.

The warp is a numerical representation of the overall curvature of the diffractive light guide plate, and may be derived as shown in the following general formula (2).

[General formula 2]

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

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

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

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

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

The diffractive light guide plate may be used 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, there is provided a method of manufacturing the above-described diffractive light guide plate.

The present inventors have discovered that when the curable composition is injected into a conventional mold equipment and cured to prepare a substrate, the cured product is peeled off from the mold substrate during curing due to curing shrinkage of the curable composition, leaving a peeling mark on the surface of the substrate to be manufactured. , recognizing that there is a problem that the thickness uniformity is greatly impaired, and also, a resin composition for imprint is applied on a substrate prepared by a molding process and dried to form a resin layer, and then the imprint process is performed on the resin layer. In the case of manufacturing a diffraction light guide plate through the recognition of the fact that it is difficult to secure high pencil hardness due to poor interfacial adhesion between the substrate and the imprinted resin layer, the present invention has been developed.

The method for manufacturing a diffraction 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 flat upper substrate Preparing a mold equipment comprising a template in which the diffraction grating pattern included in the upper substrate is engraved, and the molding space is partitioned by the cushioning spacer;

buffering a curable composition in the molding space; and

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

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

The step of 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 the flat top substrate + curing shrinkage force of the curable composition) Х 0.95} ≤ Compressive stress of the cushioning spacer ≤ {(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 1.05}.

In the diffraction light guide plate manufacturing method according to the other embodiment, due to the use of the buffer-type 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 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 at the same time the diffraction grating pattern engraved in the template is pressed on the upper or lower portion of the cured product, diffraction on one surface of the finally manufactured diffraction light guide plate A grid pattern may be formed. For this reason, it is possible to manufacture a diffraction light guide plate including an optical layer having a diffraction grating pattern formed on one surface in a simple one-step process without performing an additional resin layer forming process and imprint process, and the diffraction grating pattern Since it is formed in an integrated structure without an interface on one surface of the optical layer, mechanical properties such as pencil hardness and strength are excellent.

On the other hand, the compressive stress of the buffer type spacer satisfies Equation 1 above. Since the compressive stress of the cushioning spacer has a difference within 5% of the sum of the load of the flat upper substrate and the curing shrinkage force of the curable composition, according to the shrinkage during curing of the curable composition in the step of curing 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 excellent thickness uniformity can be achieved.

In addition, since the compressive stress of the buffer-type 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. The diffraction grating pattern may appear clearly as a diffraction grating pattern on one surface of the cured product.

On the other hand, when the compressive stress of the buffer-type spacer is less than {(load of the flat top substrate + curing shrinkage force of the curable composition) Х 0.95}, curing is completed before equilibrium is reached, resulting in non-uniformity of the diffraction light guide plate thickness, The diffraction grating pattern may not appear clearly. In addition, when the compressive stress of the buffer-type spacer is greater than {(load of flat upper substrate + curing shrinkage force of curable composition) Х 1.05}, non-uniformity of shrinkage during curing may occur, 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, Equation 1-2, or Equation 1-3 below.

[Equation 1-1]

{(Load of flat top substrate + curing shrinkage of curable composition) Х 0.97} ≤ Compressive stress of cushioning spacer ≤ {(Load of flat top substrate + curing shrinkage of curable composition) Х 1.03}

[Equation 1-2]

{(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 0.98} ≤ Compressive stress of the cushioning spacer ≤ {(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 1.02}

[Equation 1-3]

{(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 0.99} ≤ Compressive stress of the cushioning spacer ≤ {(Load of the flat top substrate + curing shrinkage force of the 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 shrinkage force of the curable composition, and thus manufactured The diffractive light guide plate may exhibit better surface flatness and better thickness uniformity.

The unit of the load of the flat upper substrate, the curing shrinkage force of the curable composition, and the compressive stress of the buffer-type 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, since the cushioning spacer has a compressive stress in consideration of the degree of cure shrinkage as the curable composition is cured and the load of the flat upper substrate, the load of the flat upper substrate according to the cure shrinkage of the curable composition is compressed by the , and may serve to maintain a state in which the curable composition and the flat upper substrate are in close contact with each other in the step of curing the curable composition. In addition, when the template on which the diffraction grating pattern is engraved is included in the flat upper substrate and positioned on the flat upper substrate, the buffer type 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 quo.

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, it is possible to minimize deformation due to curing shrinkage during curing of the curable composition, and to minimize a decrease in transmittance during photocuring of the curable composition, and also It is possible to induce uniform curing of the curable composition by minimizing the non-uniformity of emission of reaction heat during thermal curing. On the other hand, when the template on which the diffraction grating pattern is engraved is included in the flat upper substrate and positioned on the flat upper substrate, the load of the flat upper substrate is the load due to the template on which the diffraction grating pattern is engraved. included in the load.

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

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

The molding space may be partitioned by the cushioning spacer. Specifically, when a template having a diffraction grating pattern 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 formed. can mean Alternatively, when a template on which a diffraction grating pattern is engraved is provided on the flat upper substrate, 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 for manufacturing a light guide plate according to another embodiment may include buffering a curable composition in the molding space.

Specifically, the step of buffering the curable composition includes 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 on which the diffraction grating pattern is engraved. It can mean filling enough. In particular, the curable composition can be tightly adhered to the entire surface of the engraved pattern of the template. Specifically, the step of buffering the curable composition may mean injecting the curable composition into the molding space at 95 vol% or more, 97 vol% or more, 99 vol% or more, or 100 vol%.

In addition, the buffering of the curable composition may include: injecting the curable composition into a molding space partitioned by the buffer spacer and the flat lower substrate, and laminating a flat upper substrate including the template; a method of injecting the curable composition into a molding space partitioned by a flat lower substrate including the buffer spacer and the template, and stacking 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 diffractive light guide plate. Specifically, the curable composition may be applied without limitation as long as the diffraction light guide plate can be manufactured using mold casting. For example, the curable composition may include the above-described episulfide compound, a thiol compound, and an aromatic ring compound having two or more hydroxyl groups. may 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. Meanwhile, the description of Chemical Formulas 1 to 5 is the same as described for the diffraction light guide plate.

In addition, in the photocurable composition, 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 ring compound including 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, so hardened diffraction Streaking may occur 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. When the content of the episulfide compound is too large, the content of the cured product such as a thiol compound is relatively small, and uncured by-products are generated. ), there is a problem with 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 an uncured by-product is generated, thereby generating diffraction which is a cured product. There is a problem in that the glass transition temperature of the light guide plate is lowered and the yellow index (YI) is increased.

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 large, 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 low, so that uncured by-products are generated. There is a problem in that the glass transition temperature of the light guide plate is lowered and the yellow index (YI) is increased. On the other hand, if the content of the thiol compound is too small, the content of other compositions such as the episulfide compound is relatively high, and uncured by-products are generated, which lowers the glass transition temperature of the diffraction light guide plate, which is a cured product, and reduces the yellowness ( There is a problem in increasing the YI (Yellow Index)

In addition, in the aromatic ring compound containing two or more hydroxyl groups included in the photocurable composition, in the curing reaction of the episulfide compound and the thiol compound, two or more hydroxyl groups are ring-opening polymerization reaction with the episulfide compound to achieve crosslinking. It proceeds, and it is possible to control the curing reaction rate due to the ring-opening polymerization reaction taking place at a reaction rate slower than that of the thiol compound, for example, 1/1,000 reaction rate. In addition, in the aromatic ring compound containing two or more hydroxyl groups, the aromatic ring may control the curing reaction rate due to the ring-opening polymerization reaction occurring at a slower reaction rate than the aliphatic hydroxyl group, for example, a reaction rate of 1/2. Therefore, it is possible to prevent a rapid curing reaction from occurring even after mixing the curable composition, so that the curing reaction does not proceed for more than 7 days in a long-term storage, for example, a temperature condition of 0 ° C. It is possible to prevent the streak phenomenon in

In addition, in the total 100% by weight of the photocurable composition, the content of the aromatic ring 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. When the content of the aromatic ring compound containing two or more hydroxyl groups is too large, there is a problem in that it cannot be sufficiently dissolved in the curable composition or the refractive index of the diffractive light guide plate, which is a cured product, is lowered. .

In addition, the photocurable composition may further include a catalyst. The catalyst is not particularly limited as long as it serves to speed up the curing reaction of the curable composition, but for example, imidazole, 2-methylimidazole, 2-ethylimidazole, and 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; Phosphorus compounds, such as a triphenylphosphine, etc. are mentioned. In addition, as a commercially available thing, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (all are the brand names of an imidazole type compound) by Shikoku Kasei Kogyo Co., Ltd., U-CAT3503N, UCAT3502T by San Apro, for example. (all are brand names of the block isocyanate compound of dimethylamine), DBU, DBN, U-CATSA102, U-CAT5002 (all are bicyclic amidine compounds and its salt), etc. are mentioned.

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 large, the curing reaction proceeds rapidly, and there is a problem in handling safety of 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, optical and mechanical properties of the hardened diffractive light guide plate may be deteriorated due to non-curing.

In addition, the curable composition may further include other additives used to impart a specific function to a substrate for a display in the technical field to which the present invention pertains, such as 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 cure shrinkage rate 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 occurring due to rapid curing. 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, 100 to 200 cP.

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

2 is a view schematically showing a cross-section of the mold equipment in the step of curing the curable composition. Specifically, FIG. 2 shows a molding equipment including a cushioning spacer 503 provided between a flat lower substrate 501 and a flat upper substrate 502 including a template 504 on which a diffraction grating pattern is engraved. In the molding space, it shows that the curable composition 600 is injected and buffered. As such, after the curable composition is buffered, the diffractive light guide plate may be manufactured by photocuring and/or thermosetting the composition.

The rate of temperature increase during heat treatment of the curable composition for thermosetting may be 2 °C/min or less, 1 °C/min or less, or 0.1 to 0.5 °C/min. When the temperature increase rate is within the above range, it is possible to induce uniform curing of the curable composition by minimizing the deviation between positions of heat transferred to the curable composition and minimizing the non-uniformity of discharging heat of reaction.

The final temperature during the thermal curing may be 50 to 100 ℃, or 60 to 80 ℃, between the positions of heat transferred to the curable composition by placing an isothermal holding section at a temperature lower than the final temperature three or more times before reaching the final temperature deviation can be minimized. The temperature difference between the isothermal maintenance sections may be 10° C. to 20° C., and the holding times of the isothermal maintenance sections may be 1 hour to 5 hours, respectively. For example, after the curable composition was left at room temperature (25 °C) for 2 hours, heat cured at 45 °C for 2 hours, 60 °C for 2 hours, 75 °C for 2 hours, and 90 °C for 4 hours to form 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 are within the above ranges, a bowing phenomenon of the flat upper substrate may be minimized, and thus the thickness uniformity of the manufactured diffractive light guide plate may be greatly increased. .

The flexural modulus of the template on 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 on which the diffraction grating pattern is engraved is less than 1 GPa, the uniformity of the diffraction grating pattern may be damaged as the curing and shrinkage of the curable composition exceeds 20 GPa, and the diffraction grating pattern engraved on the template with excessive stiffness if it exceeds 20 GPa 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 also be significantly improved compared to that of a general diffractive light guide plate.

A method of measuring the surface flatness is as follows. Specifically, in 25 ℃ and 50 RH% atmosphere, QED's ASI (aspheric stitching interferometry) equipment to measure one point per 0.16 Х 0.16 ㎟ in an area of 200 mm in diameter, or using a three-dimensional shape measuring instrument of Deokin Corporation, It can be measured as a value obtained by the difference between the highest and lowest values of heights measured at intervals of 5 mm and 11.25 degrees with respect to an arbitrary origin in an area of 200 mm in diameter.

Each of the flat lower substrate and the flat upper substrate may be a transparent substrate. Specifically, each of the flat lower substrate and the flat upper substrate may be an organic substrate, which can effectively photo-cur the curable composition due to excellent light transmittance.

The compressive elastic modulus of the cushioning 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 cushioning spacer is within the above range, the load is uniformly transmitted 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 appear clearly as a diffraction grating pattern on one surface of the cured product.

A method of measuring the compressive elastic modulus of the cushioning spacer is as follows. Specimen deformation ((initial thickness-thickness after deformation)/initiality measured during compression with a specimen area of 5 Х 5 ㎟ and a compression rate of 1 mm/min using TA's Texture Analyzer in an atmosphere of 25 ℃ and 50 RH% thickness). In addition, the compressive elastic modulus of the cushioning spacer when the cushioning spacer is composed of two or more different layers is the force measured when a laminated specimen is prepared with an area of 5 Х 5 ㎟ and compressed at a compression rate of 1 mm/min. It can be a measure of the slope with respect to 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. On the other hand, when the cushioning spacer has 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, the compressive elastic modulus of the cushioning 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, the non-elastic layer may serve as a support, and the elastic layer may serve to adjust the height change according to the shrinkage of the curable composition. have.

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

The cure shrinkage rate of the curable composition may be derived as shown in the following general formula (3).

[General Formula 3]

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

The method for manufacturing a diffractive light guide plate according to another embodiment may further include obtaining the diffractive light guide plate from the mold equipment. Specifically, the obtaining of the diffraction light guide plate may include removing the flat upper substrate, the flat lower substrate, and the template in which the diffraction grating pattern is engraved to obtain the diffractive light guide plate. The removal of the flat upper substrate, the flat lower substrate and the template includes, after the curing of the curable composition is completed, the flat upper substrate, the flat lower substrate and the template in a diffraction light guide plate that is a cured product of the curable composition. It could mean to separate.

The description of the thickness and thickness deviation, refractive index, glass transition temperature, haze, etc. of the diffractive light guide plate manufactured by the method for manufacturing the diffractive light guide plate according to the other embodiment is as described in the above-described diffractive 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 can 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 thickness of the diffractive light guide plate is within the above range depending on the purpose of the diffractive light guide plate. The thickness can be adjusted.

Surfaces of the flat lower substrate, the flat upper substrate, and the template on which the diffraction grating pattern is engraved may be surface-treated with a release agent, respectively. The release agent may be applied without limitation as long as it is generally used in the art. For example, the surface-treated with the release agent may be surface-coated using a fluorine-based silane coupling agent. When the surface is coated using the release agent, in the step of obtaining the diffraction light guide plate, damage to the surface of the diffraction 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, light compared to glass or tempered glass, and capable of realizing a high refractive index Also, it is possible to provide a method for manufacturing a diffractive light guide plate capable of manufacturing such a diffractive light guide plate in a simple one-step process.

1 is a diagram schematically illustrating a cross-section of an optical layer included in a diffractive light guide plate according to an exemplary embodiment of the present invention.
2 is a diagram schematically illustrating a cross-section of a mold equipment in a step of curing a curable composition in a method for manufacturing a diffraction light guide plate according to another embodiment of the present invention.

The invention is described in more detail in the following examples. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

Preparation Example 1: Preparation of a 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 - A curable composition comprising 1.0 parts by weight of dicyclohexylmethylamine was prepared.

The cure shrinkage force of the prepared curable composition was measured by the above-described method for measuring cure shrinkage force, and the compressive stress coefficient calculated by dividing the measured cure 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 cure shrinkage force of the prepared curable composition was measured by the above-described method for measuring cure shrinkage force, and the compressive stress coefficient calculated by dividing the measured cure 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 size 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 comprising

<Examples and Comparative Examples: Preparation of a 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 with a diffraction grating pattern engraved on the lower substrate (flexural modulus: 3 GPa) was prepared. attached. At this time, it was attached so that the circle center of the lower substrate and the circle center of the template were in contact, the template had a diameter of 150 mm and a thickness of 200 µm, polyethylene terephthalate (PET), and the pitch of the engraved diffraction grating pattern was 405 nm, and the depth was 500 nm.

After that, a molding space is formed by providing buffer-type spacers made of silicon with a compressive elastic modulus of 1.0 MPa, a height of 1,007 μm, and a cross-sectional area of 10 Х 10 mm2 at 120° intervals so as to be in contact with the circumference of the lower substrate. After injecting the curable composition prepared according to Preparation Example 1 into the molding space, as an upper substrate, 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 was used. was buffered in the molding space.

Furthermore, the curable composition was placed in a convection oven of Jiotech, left at room temperature for 2 hours, the temperature increase rate was set to 1°C/min, and then at 45°C for 2 hours, at 60°C for 2 hours, and at 75°C for 2 hours. , to prepare a diffractive light guide plate having a thickness of 0.8 mm by thermal curing at 90° C. for 4 hours.

Comparative Example 1

A diffraction 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

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 used as the lower substrate, and a compressive elastic modulus of 1.0 MPa, a height of 804 µm, and a cross-sectional area of 10 Х 10 mm2 was used. After forming a molding space by providing buffer-type spacers made of silicon at 120° intervals so as to be in contact with the circumference of the lower substrate, the curable composition prepared according to Preparation Example 1 is injected into the molding space, and then bending 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.

Furthermore, the curable composition was placed in a convection oven of Jiotech, left at room temperature for 2 hours, the temperature increase rate was set to 1°C/min, and then at 45°C for 2 hours, at 60°C for 2 hours, and at 75°C for 2 hours. , and thermosetting 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 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 is engraved on the imprint resin layer was applied at 40° C. temperature and 20 bar pressure conditions. After forming a diffraction grating by pressing in the , 1000 mJ/cm ² UV (360 nm light source) was irradiated and cured to prepare a diffraction light guide plate having a thickness of 0.8 mm, and cut into a 6 Х 5 cm rectangle.

Comparative Example 3

A diffraction 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. Measuring refractive index

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

2. Haze measurement

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

3. Pencil hardness measurement

After fixing a pencil at a load of 0.5 kg and an angle of 45° on the surface of the diffraction light guide plate of Examples and Comparative Examples, it was determined whether or not the pencil was scratched by the pencil hardness, and the maximum pencil hardness that does not cause scratches is shown in Table 1 below. .

4. Warp measurement

For the diffraction light guide plates of Examples and Comparative Examples, specimens of a rectangular region having a major axis of 600 mm and a minor axis of 400 mm were prepared, and the 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 midplane and reference plane - minimum deviation between midplane and reference plane

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

5. Measurement of Glass Transition Temperature

Glass transition temperatures (Tg) were measured for the diffraction guide plates of Examples 1 and 2 and the plastic substrates of Comparative Examples 2 and 3 using Perkin Elmer's Pyris 6 Differential Scanning Calorimetry (DSC), 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 (μm) 20 24 55 68 Glass transition temperature (℃) 85 74 85 74

According to Table 1 below, the 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 diffraction light guide plate of Example 1 had high refractive index and glass transition temperature, excellent pencil hardness, and low warp and haze and high visibility.

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

200: diffraction grating pattern 300: optical layer
400: pattern unit 501: flat lower substrate
502: flat upper substrate 503: cushioning spacer
504: diffraction grating pattern engraved template 600: curable composition

Claims (19)

A diffraction grating pattern comprising an optical layer formed on one surface,
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 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,
The diffraction light guide plate, wherein the aromatic ring compound having two or more hydroxyl groups is at least one selected from compounds represented by the following formula (4):
[Formula 4]

In 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, cycloalkyl 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;
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.
According to claim 1,
The diffraction grating pattern and one surface of the optical layer have a refractive index of 1.65 or more, respectively.
According to 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.
According to claim 1,
The episulfide compound includes a compound represented by the following formula (1),
The thiol compound is a diffraction light guide plate comprising at least one selected from compounds represented by the following Chemical Formulas 2 and 3:
[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 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 Formula 2,
R ₅ and R ₆ are each independently a single bond or 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 Formula 3,
Ring A is a 5-membered or 6-membered aromatic heterocyclic ring containing at least one of nitrogen (N) and sulfur (S) atoms,
e is an integer from 1 to 3.
According to claim 1,
The diffractive light guide plate has a thickness of 0.1 to 10 mm.
According to claim 1,
The diffraction grating pattern includes one or more pattern units,
The diffraction light guide plate, wherein a pitch between the pattern units is 0.1 to 1 μm, and a height is 0.1 to 1 μm.
According to claim 1,
A 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 more,
A thickness variation of the diffractive light guide plate is 3.0% or less.
According to 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.
According to claim 1,
The diffractive light guide plate is for a diffractive light guide lens of a wearable device.
A flat lower substrate, a flat upper substrate, a buffer spacer positioned between the flat lower substrate and the flat upper substrate, and a template in which a diffraction grating pattern included in the flat lower substrate or the flat upper substrate is engraved (template), comprising the steps of preparing a molding equipment in which the molding space is partitioned by the buffer spacer;
buffering a curable composition in the molding space; and
Including; compressing the curable composition under the load of the flat upper substrate, and curing the curable composition;
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 a load of the flat upper substrate, and curing the curable composition is performed to satisfy Equation 1 below:
[Equation 1]
{(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 0.95} ≤ Compressive stress of the cushioning spacer ≤ {(Load of the flat top substrate + curing shrinkage force of the curable composition) Х 1.05}.
11. The method of claim 10,
and a flexural modulus of each of the flat lower substrate and the flat upper substrate is 3 GPa or more.
11. The method of claim 10,
The template on which the diffraction grating pattern is engraved has a flexural modulus of 1 to 20 GPa.
11. The method of claim 10,
Surface flatness of the flat lower substrate and the flat upper substrate is 5 μm or less, respectively.
11. The method of claim 10,
The compression elastic modulus of the cushioning spacer is 0.1 to 10 MPa, the diffraction light guide plate manufacturing method.
11. The method of claim 10,
The buffer spacer has a structure in which an inelastic layer and an elastic layer are laminated, an elastic layer is provided between the inelastic layers, or a structure in which an inelastic layer is provided between the elastic layers.
11. 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.
11. The method of claim 10,
The episulfide compound includes a compound represented by the following formula (1),
The thiol compound includes at least one selected from compounds represented by the following Chemical Formulas 2 and 3,
The method for manufacturing a diffraction light guide plate, wherein the aromatic ring compound having two or more hydroxyl groups includes at least one selected from compounds represented by the following Chemical Formulas 4 and 5:
[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 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 Formula 2,
R ₅ and R ₆ are each independently a single bond or 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 Formula 3,
Ring A is a 5-membered or 6-membered aromatic heterocyclic ring containing at least one of nitrogen (N) and sulfur (S) atoms,
e is an integer from 1 to 3,
[Formula 4]

In 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, cycloalkyl 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;
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 Formula 5,
Ar ₁ and Ar ₂ are each independently an 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, al 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 from 0 to 4.
11. The method of claim 10,
The curing shrinkage of the curable composition is 15% or less, the diffraction light guide plate manufacturing method.
11. 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.

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