DIFFRACTION LIGHT GUIDE PLATE AND MANUFACTURING METHOD THEREOF

Abstract

A diffraction light guide plate comprising an optical layer having diffraction lattice pattern formed as an integrated structure without an interface on one surface thereof, where the optical layer having diffraction lattice pattern is a continuous phase of polymer comprising an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups, the diffraction light guide plate having excellent thickness uniformity and flatness as well as low haze and excellent visibility, and excellent mechanical properties such as pencil hardness and strength, and a method for manufacturing the diffraction light guide plate.

Claims

1. A diffraction light guide plate comprising an optical layer having a diffraction lattice pattern formed on one surface, wherein the diffraction lattice pattern is formed as an integrated structure without an interface on the one surface of the optical layer, wherein a difference in refractive index between the diffraction lattice pattern and the one surface of the optical layer is 0.01 or less, and wherein the optical layer having diffraction lattice pattern formed on one surface is a continuous phase of polymer comprising an episulfide compound, a thiol compound, and an aromatic cyclic compound including two or more hydroxyl groups.

2. The diffraction light guide plate according to claim 1, wherein the diffraction lattice pattern and the one surface of the optical layer respectively have a refractive index of 1.65 or more.

3. The diffraction light guide plate according to claim 1, wherein the weight ratio of the thiol compound to the aromatic cyclic compound having two or more hydroxyl groups is 5:5 to 9:1.

4. The diffraction light guide plate according to claim 1, wherein the episulfide compound comprises a compound represented by the following Chemical Formula 1, wherein the thiol compound comprises at least one selected from compounds represented by the following Chemical Formulas 2 and 3, and wherein the aromatic cyclic compound having two or more hydroxyl groups comprises at least one selected from compounds represented by the following Chemical Formulas 4 and 5: ##STR00009## in Chemical Formula 1, R.sub.1 and R.sub.2 are each independently; hydrogen or C1 to C10 alkyl, R.sub.3 and R.sub.4 are each independently; a single bond or C1 to C10 alkylene, a is an integer of 0 to 4, and b is an integer of 0 to 6, ##STR00010## in Chemical Formula 2, R.sub.5 and R.sub.6 are each independently; a single bond or C1 to C10 alkylene, c is an integer of 0 to 4, and d is an integer of 0 to 6, ##STR00011## in Chemical Formula 3, ring A is a 5- or 6-membered aromatic heterocycle comprising one or more of nitrogen(N) and sulfur(S) atoms, and e is an integer of 1 to 3, ##STR00012## in Chemical Formula 4, R.sub.7 and R.sub.8 are each independently; deuterium, halogen, cyano, nitrile, nitro, amino, C1 to C40 alkyl, C1 to C40 alkoxy, C3 to C40 cycloalkyl, C1 to C40 alkenyl, C6 to C60 aryl, or C1 to C40 heteroaryl comprising one or more 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, and g+I is an integer of 7 or less, ##STR00013## in Chemical Formula 5, Ar.sub.1 and Ar.sub.2 are each independently C6 to C60 aryl substituted with one or more hydroxyl groups, R.sub.9 and R.sub.10 are each independently; deuterium, halogen, cyano, nitrile, nitro, amino, C1 to C40 alkyl, C1 to C40 alkoxy, C3 to C40 cycloalkyl, C1 to C40 alkenyl, C6 to C60 aryl, or C1 to C40 heteroaryl comprising one or more of O, N, Si and S, and m and n are each independently; an integer of 0 to 4.

5. The diffraction light guide plate according to claim 1, wherein the thickness of the diffraction light guide plate is 0.1 to 10 mm.

6. The diffraction light guide plate according to claim 1, wherein the diffraction lattice pattern comprises two or more pattern units, and a pitch between the pattern units is 0.1 to 1 μm, and a height of the pattern units is 0.1 to 1 μm.

7. The diffraction light guide plate according to claim 1, wherein warp of the diffraction light guide plate is 100 μm or less, wherein haze of the diffraction light guide plate is 4.0% or less, wherein pencil hardness of the diffraction light guide plate is HB or more, and wherein thickness deviation of the diffraction light guide plate is 3.0% or less.

8. The diffraction light guide plate according to claim 1, wherein transmittance of the diffraction light guide plate is 80% or more, and wherein YI(Yellow Index) of the diffraction light guide plate is 1 to 30.

9. The diffraction light guide plate according to claim 1, wherein the diffraction light guide plate is for a diffraction light guide lens of a wearable device.

10. A method for manufacturing a diffraction light guide plate comprising steps of: preparing a mold equipment comprising a flat lower substrate, a flat upper substrate, buffer spacers positioned between the flat lower substrate and the flat upper substrate, and a template engraved with a diffraction lattice pattern; included in the flat lower substrate or flat upper substrate, where a molding space is partitioned by the buffer spacers; fully charging a curable composition in the molding space; and compressing the curable composition with a 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 cyclic compound having two or more hydroxyl groups, and wherein the step of compressing the curable composition with a load of the flat upper substrate and curing the curable composition is conducted so as to fulfill the following Formula 1:
{(load of flat upper substrate+shrinking force of curable composition)×0.95}≤compressive stress of buffer spacer≤{(load of flat upper substrate+shrinking force of curable composition)×1.05}.  [Formula 1]

11. The method for manufacturing a diffraction light guide plate according to claim 10, wherein flexural modulus of the flat lower substrate and the flat upper substrate are respectively 3 GPa or more.

12. The method for manufacturing a diffraction light guide plate according to claim 10, wherein the template engraved with a diffraction lattice pattern has flexural modulus of 1 to 20 GPa.

13. The method for manufacturing a diffraction light guide plate according to claim 10, wherein surface flatness of the flat lower substrate and the flat upper substrate are respectively 5 μm or less.

14. The method for manufacturing a diffraction light guide plate according to claim 10, wherein elastic modulus of compressibility of the buffer spacer is 0.1 to 10 MPa.

15. The method for manufacturing a diffraction light guide plate according to claim 10, wherein the buffer spacer has a structure in which a non-elastic layer and an elastic layer are laminated, a structure in which an elastic layer is positioned between non-elastic layers, or a structure in which a non-elastic layer is positioned between elastic layers.

16. The method for manufacturing a diffraction light guide plate according to claim 10, wherein the weight ratio of the thiol compound to the aromatic cyclic compound having two or more hydroxyl groups is 5:5 to 9:1.

17. The method for manufacturing a diffraction light guide plate according to claim 10, wherein the episulfide compound comprises a compound represented by the following Chemical Formula 1, wherein the thiol compound comprises at least one selected from compounds represented by the following Chemical Formulas 2 and 3, and wherein the aromatic cyclic compound having two or more hydroxyl groups comprises at least one selected from compounds represented by the following Chemical Formulas 4 and 5: ##STR00014## in Chemical Formula 1, R.sub.1 and R.sub.2 are each independently hydrogen or C1 to C10 alkyl, R.sub.3 and R.sub.4 are each independently a single bond or C1 to C10 alkylene, a is an integer of 0 to 4, and b is an integer of 0 to 6, ##STR00015## in Chemical Formula 2, R.sub.5 and R.sub.6 are each independently a single bond or C1 to C10 alkylene, c is an integer of 0 to 4, and d is an integer of 0 to 6, ##STR00016## in Chemical Formula 3, A—ring A is a 5- or 6-membered aromatic heterocycle comprising one or more of nitrogen(N) and sulfur(S) atoms, and e is an integer of 1 to 3, ##STR00017## in Chemical Formula 4, R.sub.7 and R.sub.8 are each independently deuterium, halogen, cyano, nitrile, nitro, amino, C1 to C40 alkyl, C1 to C40 alkoxy, C3 to C40 cycloalkyl, C1 to C40 alkenyl, C6 to C60 aryl, or C1 to C40 heteroaryl comprising one or more 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, and g+I is an integer of 7 or less, ##STR00018## in Chemical Formula 5, Ar.sub.1 and Ar.sub.2 are each independently; C6 to C60 aryl substituted with one or more hydroxyl groups, R.sub.9 and R.sub.10 are each independently; deuterium, halogen, cyano, nitrile, nitro, amino, C1 to C40 alkyl, C1 to C40 alkoxy, C3 to C40 cycloalkyl, C1 to C40 alkenyl, C6 to C60 aryl, or C1 to C40 heteroaryl comprising one or more of O, N, Si and S, and m and n are each independently; an integer of 0 to 4.

18. The method for manufacturing a diffraction light guide plate according to claim 10, wherein cure shrinkage of the curable composition is 15% or less.

19. The method for manufacturing a diffraction light guide plate according to claim 10, wherein the curable composition has a viscosity of 4000 cP or less; after maintained at a temperature of −5 to 0° C. for 12 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0167] FIG. 1 is a schematic diagram of the cross-section of the optical layer included in the diffraction light guide plate according to one embodiment of the present disclosure.

[0168] FIG. 2 is a schematic diagram of the cross-section of mold equipment, in the step of curing a curable composition, in the manufacturing method of a diffraction light guide plate according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

[0169] The present disclosure will be explained in detail in the following examples. However, these examples are presented only as the illustrations of the present disclosure, and the scope of the present disclosure is not limited thereby.

Preparation Example 1: Preparation of Curable Composition

[0170] A curable composition comprising 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 1.0 part by weight of a catalyst N,N-dicyclohexylmethylamine was prepared.

[0171] The cure shrinkage of the prepared curable composition was measured by the above explained measurement method of cure shrinkage, and modulus of compressive stress calculated by dividing the measured cure shrinkage by the volume of a sample was 2.5*10.sup.3 N/m.sup.3.

Preparation Example 2: Preparation of Curable Composition

[0172] 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 part by weight of a catalyst N,N-dicyclohexylmethylamine was prepared.

[0173] The cure shrinkage of the prepared curable composition was measured by the above explained measurement method of cure shrinkage, and modulus of compressive stress calculated by dividing the measured cure shrinkage by the volume of a sample was 2.5*10.sup.3 N/m.sup.3.

Preparation Example 3: Preparation of Imprint Resin Composition

[0174] An imprint resin composition comprising 8.3 parts by weight of zirconia particles having a 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-trimethylbenzoyl)phenylphosphinate was prepared.

Examples and Comparative Examples: Manufacture of Diffraction Light Guide Plate

Example 1

[0175] A glass substrate having a flexural modulus of 70 GPa, surface flatness of 0.5 μm, thickness of 30 mm and diameter of 200 mm was prepared as a lower substrate, and on the lower substrate, a template (flexural modulus: 3 GPa) engraved with a diffraction lattice pattern was attached. Wherein, it was attached such that the center of the lower substrate and the center of the template contact, the template was polyethyleneterephthalate(PET) having a diameter of 150 mm and thickness of 200 μm, and the pitch of the engraved diffraction lattice pattern was 405 nm and the depth was 500 nm.

[0176] Thereafter, buffer spacers made of silicon, having elastic modulus of compressibility of 1.0 MPa, height of 1,007 μm, and cross-section of 10×10 mm.sup.2 were positioned at the interval of 120° so as to contact the circumference of the lower substrate, thus forming molding spaces, and then, the curable composition prepared according to Preparation Example 1 was injected into the molding spaces, and using a glass substrate having flexural modulus of 70 GPa, load of 8.2 N, diameter of 200 mm, and surface flatness of 0.5 μm as a upper substrate, the curable composition was fully charged in the molding spaces.

[0177] And, the curable composition was put in a convection oven from Jeio Tech Co., Ltd., and left at room temperature for 2 hours, and then, a temperature rise speed was set to 1° C./min, and it was photocured at 45° C. for 2 hours, at 60° C. for 2 hours, at 75° C. for 2 hours, and at 90° C. for 4 hours to manufacture a diffraction light guide plate with a thickness of 0.8 mm.

Comparative Example 1

[0178] A diffraction light guide plate was manufactured by the same method as 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

[0179] A glass substrate having a flexural modulus of 70 GPa, surface flatness of 0.5 μm, thickness of 30 mm and diameter of 200 mm was used as a lower substrate, and buffer spacers made of silicon, having elastic modulus of compressibility of 1.0 MPa, height of 804 μm, and cross-section of 10×10 mm.sup.2 were positioned at the interval of 120° so as to contact the circumference of the lower substrate, thus forming molding spaces, and then, the curable composition prepared according to Preparation Example 1 was injected into the molding spaces, and using a glass substrate having flexural modulus of 70 GPa, load of 8.2 N, diameter of 200 mm, and surface flatness of 0.5 μm as a upper substrate, the curable composition was fully charged in the molding spaces.

[0180] And, the curable composition was put in a convection oven from Jeio Tech Co., Ltd., and left at room temperature for 2 hours, and then, a temperature rise speed was set to 1° C./min, and it was thermally cured at 45° C. for 2 hours, at 60° C. for 2 hours, at 75° C. for 2 hours, and at 90° C. for 4 hours to manufacture a plastic substrate.

[0181] On the plastic substrate, the imprint resin composition(refractive index 1.70) prepared according to Preparation Example 3 was applied and dried to form an imprint resin layer with a thickness of 1 μm. And then, on the imprint resin layer, a template(diameter 150 mm, thickness 200 μm, polyethyleneterephthalate) engraved with a diffraction lattice pattern of 405 nm pitch and 1 μm depth was compressed under 40° C. temperature and 20 bar pressure conditions to form diffraction lattice, and then, irradiated by UV(360 nm light source) at 1000mJ/cm.sup.2 to prepare a diffraction light guide plate with a thickness of 0.8 mm, and it was cut to the form of 6×5 cm rectangles.

Comparative Example 3

[0182] A diffraction light guide plate was manufactured by the same method as 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.

[0183] Evaluation

[0184] 1. Measurement of Refractive Index

[0185] The refractive indexes of the diffraction light guide plates of Examples and Comparative Examples were measured using spectroscopic ellipsometry from Ellipso Technology Co. Ltd., and the results were shown in the following Table 1.

[0186] 2. Measurement of Haze

[0187] The haze of the diffraction light guide plates of Examples and Comparative Examples was measured by ASTM D-100, and the results were shown in the following Table 1.

[0188] 3. Measurement of Pencil Hardness

[0189] After fixing a pencil on the surface of each diffraction light guide plate of Examples and Comparative Examples at a load of 0.5 kg, and an angle of 45°, the surface was scratched according to pencil hardness and it was judged with the unaided eye whether or not scratched, and the maximum pencil hardness at which scratch is not generated was shown in the following Table 1.

[0190] 4. Measurement of Warp

[0191] For the diffraction light guide plates of Examples and Comparative Examples, rectangular specimens with a long axis of 60 mm and a short axis of 400 mm were prepared, warp was calculated by the following General Formula 2, and the results were shown in the following Table 1.

Warp=maximum deviation between central side and base side−minimum deviation between central side and base side  [General Formula 2]

[0192] The central side may be drawn by measuring a thickness of the diffraction light guide plate and a distance between a base optical body mounted on the lower part of the diffraction light guide plate and the diffraction light guide plate, by a non-contact measurement method using OWTM(Optical Wafer Thickness Measurement system) equipment of Fiberpro, under 25° C. and 50 RH % atmosphere. Meanwhile, the base side may be calculated by least squares fit to the central side.

[0193] 5. Measurement of Glass Transition Temperature

[0194] For the diffraction light guide plates of Examples land 2 and plastic substrates of Comparative Examples 2 and 3, glass transition temperatures(Tg) were measured using Pyris 6 DSC(Differential Scanning calorimetry) from Perkin Elmer Inc., and the results were shown in the following Table 1.

TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Example 1 Example 1 Example 2 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 85 74 85 74 temperature(° C.)

[0195] According to the Table 1, it was confirmed that the diffraction light guide plate of Example 1 having a continuous phase of polymers comprising an episulfide compound, a thiol compound, and an aromatic cyclic compound having two or more hydroxyl groups, wherein a diffraction lattice pattern is formed as an integrated structure without an interface on one surface of an optical layer, has high refractive index and glass transition temperature, excellent pencil hardness, and low haze and high visibility.

[0196] On the contrary, it was confirmed that the diffraction light guide plate of Comparative Example 1 which does not use an aromatic cyclic compound has lower refractive index and glass transition temperature and higher warp, compared to Example 1. And, it was confirmed that the diffraction light guide plates of Comparative Examples 2 and 3 wherein an interface exists between a diffraction lattice pattern and an optical layer has remarkably high warp and haze, and lowered pencil hardness, compared to Example 1.

DESCRIPTION OF REFERENCE NUMERALS

[0197] 200: diffraction lattice pattern [0198] 300: optical layer [0199] 400: pattern unit [0200] 501: flat lower substrate [0201] 502: flat upper substrate [0202] 503: buffer spacer [0203] 504: template engraved with diffraction lattice pattern [0204] 600: curable composition