KR102563408B1 - Composition for forming optical substrate and optical substrate comprising cured product thereof - Google Patents

Abstract

The present invention relates to an optical substrate having an excellent light refractive index and a composition for forming an optical substrate capable of implementing the same.

Description

A composition for forming an optical substrate and an optical substrate including a cured product thereof

The present invention relates to an optical substrate including a composition for forming an optical substrate and a cured product thereof.

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

A virtual reality device or an augmented reality device may form a diffraction guiding pattern on a lens such as general glasses to show a desired image to a user. In general, a lens for a virtual reality device or an augmented reality device uses a glass substrate having a high refractive index. The glass substrate has the advantage of having a high refractive index and light transmittance, but can cause fatal damage to the user's eyeball when broken, , It is heavy and uncomfortable to wear for a long time.

Accordingly, it is necessary to study a substrate for optics that has a high refractive index so that it can be used for virtual reality devices or augmented reality devices, and is lightweight and relatively safe when damaged.

Korean Publication No. 10-2017-0089662

The present invention provides an optical substrate having an excellent optical refractive index and a composition for forming an optical substrate capable of implementing the optical substrate.

However, the problem to be solved by the present invention is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

An exemplary embodiment of the present invention, a photoreactive monomer containing a (meth) acrylate-based compound containing an aromatic group; photoinitiators; Surfactants; polar organic solvents; and inorganic particles having a light refractive index of 2.0 or more at a wavelength of 589 nm, wherein the cured product of the photoreactive monomer has a light refractive index of 1.6 or more at a wavelength of 589 nm, and the inorganic particles contain 75 parts by weight based on 100 parts by weight of the solid content. It provides a composition for forming an optical substrate included in an amount of 90 parts by weight or less.

In addition, an exemplary embodiment of the present invention, a substrate; and a diffraction grating layer provided on one surface of the substrate and including a cured product of the composition for forming the optical substrate.

Since the composition for forming an optical substrate according to an exemplary embodiment of the present invention can implement an optical substrate having excellent optical properties, it can be easily used as a diffraction light guide plate for a virtual reality device and/or an augmented reality device.

Since the optical substrate according to one embodiment of the present invention is lightweight and has excellent optical properties, it can be easily applied as a diffraction light guide plate of a virtual reality device and/or an augmented reality device, and has the advantage of reducing user fatigue. there is.

Effects of the present invention are not limited to the above-mentioned effects, and effects not mentioned will be clearly understood by those skilled in the art from the present specification and accompanying drawings.

1 is a view schematically showing a cross section of an optical substrate according to an exemplary embodiment of the present invention.
2 is a diagram schematically illustrating a pattern structure according to an exemplary embodiment of the present invention.
3 is a schematic diagram of an optical substrate according to an embodiment of the present invention.
4 is a photograph taken using a scanning electron microscope of a cross section of an optical substrate prepared in Example 1 of the present invention.
5 is a photograph taken with a digital camera of the optical substrate prepared in Comparative Example 1 of the present invention.

In this specification, when a part is said to "include" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

Throughout the present specification, when a member is said to be located “on” another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

Throughout the present specification, the unit "parts by weight" may mean the ratio of the weight of each component.

Throughout this specification, "(meth)acrylate" is used as a generic term for acrylate and methacrylate.

Throughout this specification, "A and/or B" means "A and B, or A or B".

Throughout the present specification, the optical refractive index may be a value measured based on a wavelength of 589 nm using Spectroscopy Ellipsometry (Ellipsometer M-2000, J.A. Woollam) at 25° C. and 50 RH% and using a Cauchy Film Model.

Hereinafter, this specification will be described in more detail.

An exemplary embodiment of the present invention, a photoreactive monomer containing a (meth) acrylate-based compound containing an aromatic group; photoinitiators; Surfactants; polar organic solvents; and inorganic particles having a light refractive index of 2.0 or more at a wavelength of 589 nm, wherein the cured product of the photoreactive monomer has a light refractive index of 1.6 or more at a wavelength of 589 nm, and the inorganic particles contain 75 parts by weight based on 100 parts by weight of the solid content. It provides a composition for forming an optical substrate included in an amount of 90 parts by weight or less.

Since the composition for forming an optical substrate according to an exemplary embodiment of the present invention can implement an optical substrate having excellent optical properties, it can be easily used as a diffraction light guide plate for a virtual reality device and/or an augmented reality device. Specifically, the optical substrate including the cured product of the composition for forming the optical substrate may have an optical refractive index of 1.75 or more at a wavelength of 589 nm.

According to an exemplary embodiment of the present invention, the cured product of the photoreactive monomer has an optical refractive index of 1.6 or more at a wavelength of 589 nm. Specifically, the cured product formed by curing only the photoreactive monomer itself may have an optical refractive index of 1.6 or more, 1.61 or more, or 1.62 or more at a wavelength of 589 nm. The composition for forming an optical substrate including the photoreactive monomer whose optical refractive index after curing satisfies the above range can easily implement an optical substrate having a optical refractive index of 1.75 or more at a wavelength of 589 nm.

According to an exemplary embodiment of the present invention, the aromatic group contained in the (meth)acrylate-based compound may be a dibenzofuran group. The (meth)acrylate-based compound containing a dibenzofuran group can effectively suppress a decrease in light refractive index even after curing, and can make the cross-linked structure in the polymer matrix of the cured product dense. Through this, the composition for forming an optical substrate can implement an optical substrate having an excellent light refractive index.

According to an exemplary embodiment of the present invention, the (meth)acrylate-based compound containing the aromatic group may include one (meth)acrylate group. That is, the (meth)acrylate-based compound containing the aromatic group may be a monofunctional compound. By using a (meth)acrylate-based compound containing one (meth)acrylate group, after curing the composition for forming an optical substrate, the remaining unreacted (meth)acrylate group in the polymer matrix of the cured product is effectively suppressed. can do. Through this, the optical refractive index of the optical substrate including the cured product of the composition for forming the optical substrate may be effectively suppressed from being lowered.

According to an exemplary embodiment of the present invention, the (meth)acrylate-based compound containing the aromatic group may be a compound represented by Formula 1 or Formula 2 below.

[Formula 1]

[Formula 2]

In Chemical Formulas 1 and 2, R1 may be hydrogen or a methyl group.

According to an exemplary embodiment of the present invention, the photoreactive monomer may include one or more (meth)acrylate-based compounds containing an aromatic group. Specifically, the photoreactive monomer may be a mixture of the compounds represented by Formulas 1 and 2 above.

According to an exemplary embodiment of the present invention, the photoreactive monomer may be included in an amount of 10 parts by weight or more and 15 parts by weight or less based on 100 parts by weight of solid content. Specifically, the content of the photoreactive monomer may be 11 parts by weight or more and 14.5 parts by weight or less, 11 parts by weight or more and 13 parts by weight or less, or 10.5 parts by weight or more and 13.5 parts by weight or less, based on 100 parts by weight of the solid content. By adjusting the content of the photoreactive monomer within the above range, the optical refractive index of the optical substrate including the cured product of the composition for forming the optical substrate may be effectively improved. In addition, when the content of the photoreactive monomer is within the above range, deterioration of mechanical properties such as shear strength and durability of the cured product of the composition for forming an optical substrate may be suppressed. In addition, by adjusting the content of the photoreactive monomer within the above range, it is possible to effectively improve the pattern moldability of the composition for forming the optical substrate.

In the present specification, the “solid content” may refer to a solute or solid material excluding the solvent in the entire solution, and specifically, the solid content of the composition for forming an optical substrate includes a (meth)acrylate-based compound containing an aromatic group. It may mean including a photoreactive monomer, a photoinitiator, a surfactant, inorganic particles and additives. That is, the composition for forming the optical substrate may be composed of a polar organic solvent and a solid content including a photoreactive monomer, a photoinitiator, a surfactant, inorganic particles, and additives.

According to an exemplary embodiment of the present invention, the inorganic particles have a light refractive index of 2.0 or more at a wavelength of 589 nm. Specifically, the inorganic particles may have an optical refractive index of 2.1 or more, or 2.2 or more at a wavelength of 589 nm. The optical refractive index of the optical substrate including the cured product of the composition for forming the optical substrate may be effectively improved by using inorganic particles having a light refractive index at a wavelength of 589 nm that satisfies the above range.

According to an exemplary embodiment of the present invention, the optical refractive index of the inorganic particles may be measured using a device and/or method for measuring the optical refractive index of inorganic particles in the art. In the present invention, the optical refractive index of the inorganic particles at a wavelength of 589 nm can be calculated using a spectroscopy ellipsometry device and a Cauchy film model. For example, a cured product of a composition prepared by mixing 50 parts by weight of inorganic particles with 50 parts by weight of a photoreactive monomer (refractive index; RI _monomer ) is an RI _{cured product} , the volume fraction of the photoreactive monomer is V _monomer , and the volume fraction of the inorganic particles In the case of V _particles , since RI _{cured product} = (RI _monomer × V _monomer ) + (RI _particle × V _particle ), the refractive index of the inorganic particle (RI _particle ) can be calculated using this.

According to an exemplary embodiment of the present invention, the inorganic particles may include at least one of silica, alumina, zirconia, zeolite, and titanium oxide having the aforementioned light refractive index. In terms of light transmittance, haze, and yellow index of the optical substrate including the cured product of the composition for forming the optical substrate, the inorganic particles may include at least zirconia.

According to one embodiment of the present invention, the inorganic particles may have a diameter of 25 nm or less. Specifically, the inorganic particle may have a diameter of 20 nm or less, 15 nm or less, or 10 nm or less. That is, the inorganic particles may be nano-inorganic particles. Also, the diameter of the inorganic particles may be an average diameter.

By adjusting the diameter of the inorganic particles within the above range, the inorganic particles can maintain high dispersibility in the composition for forming an optical substrate, and impart transparency to a cured product of the composition for forming an optical substrate to increase the optical refractive index. can be greatly improved. In addition, when the diameter of the inorganic particles is within the aforementioned range, the inorganic particles may be stably dispersed and present in the diffraction guide pattern of the optical substrate prepared using the composition for forming the optical substrate. Through this, it is possible to effectively improve the light refractive index of the optical substrate.

According to an exemplary embodiment of the present invention, the diameter of the inorganic particle may be measured using a device and/or method for measuring the diameter of the inorganic particle in the art. For example, using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), the inorganic particles are photographed, the diameters of the inorganic particles in the photographed images are measured, and the average value thereof can be obtained to obtain the average diameter.

According to an exemplary embodiment of the present invention, the surface of the inorganic particle may be capped with an organic material. For example, the surface of the inorganic particle may be capped with an organic material having a light refractive index of about 1.5 at a wavelength of 589 nm to a thickness of 1.5 nm.

According to an exemplary embodiment of the present invention, the inorganic particles are included in an amount of 75 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of solid content. Specifically, the content of the inorganic particles is 80 parts by weight or more and 90 parts by weight or less, 82 parts by weight or more and 88.5 parts by weight or less, 83.5 parts by weight or more and 87 parts by weight or less, or 84.5 parts by weight or more and 85.5 parts by weight, based on 100 parts by weight of the solid content. may be less than

By adjusting the content of the inorganic particles within the above range, the optical refractive index of the optical substrate including the cured product of the composition for forming the optical substrate at a wavelength of 589 nm can be easily controlled to 1.75 or more. In addition, when the content of the inorganic particles is within the above range, the composition for forming an optical substrate has excellent pattern formability, and the light transmittance, haze, and yellowness of an optical substrate including a cured product of the composition for forming an optical substrate Deterioration of the optical properties of the index can be prevented.

According to an exemplary embodiment of the present invention, the weight ratio of the photoreactive monomer to the inorganic particles may be 1:3 to 1:9. Specifically, the weight ratio of the photoreactive monomer to the inorganic particles may be 1:3 to 1:8, 1:3 to 1:6, 1:7 to 1:8.5, or 1:7.5 to 1:8. By adjusting the weight ratio of the photoreactive monomer and the inorganic particles within the above range, the optical refractive index of the optical substrate including the cured product of the composition for forming the optical substrate at a wavelength of 589 nm can be easily controlled to 1.75 or more. . In addition, when the weight ratio of the photoreactive monomer and the inorganic particles is within the above range, the optical properties of light transmittance, haze, and yellow index of the optical substrate including the cured product of the composition for forming the optical substrate can be implemented at appropriate levels. can

According to one embodiment of the present invention, the surfactant may be a fluorine-based surfactant. By using a fluorine-based surfactant, compatibility between the photoreactive monomer and the inorganic particles can be effectively improved, and through this, light transmittance of an optical substrate including a cured product of the composition for forming an optical substrate can be improved. .

According to an exemplary embodiment of the present invention, the surfactant may be included in an amount of 2 parts by weight or more and 5 parts by weight or less based on 100 parts by weight of the solid content. Specifically, the content of the surfactant may be 2.5 parts by weight or more and 4.5 parts by weight or less, or 2.8 parts by weight or more and 3.5 parts by weight or less, based on 100 parts by weight of the solid content.

By adjusting the content of the surfactant within the above range, the surface energy of the cured product of the composition for forming an optical substrate may be effectively reduced. Through this, it is possible to effectively improve the surface flatness of the cured product, and there is an advantage in that the surface of the composition for forming the optical substrate is molded using a mold and the mold can be more easily removed after curing the composition. .

According to an exemplary embodiment of the present invention, the photoinitiator may be included in an amount of 0.1 parts by weight or more and 1 part by weight or less based on 100 parts by weight of solid content. Specifically, the content of the photoinitiator is 0.15 parts by weight or more and 0.8 parts by weight or less, 0.2 parts by weight or more and 0.7 parts by weight or less, 0.3 parts by weight or more and 0.6 parts by weight or less, or 0.4 parts by weight or more and 0.55 parts by weight, based on 100 parts by weight of the solid content. may be below. By adjusting the content of the photoinitiator within the above range, the photocuring reaction of the composition for forming an optical substrate may be stably performed.

According to an exemplary embodiment of the present invention, the photoinitiator may be a benzophenone-based compound, an acetophenone-based compound, a biimidazole-based compound, a triazine-based compound, an oxime-based compound, or a mixture thereof. Specifically, specific examples of the photoinitiator include benzophenone, benzoyl methyl benzoate, acetophenone, 2,4-diethyl thioxanthone, 2 -Chloro thioxanthone (2-chloro thioxanthone), ethyl anthraquinone (ethyl anthraquinone), 1-hydroxy cyclohexyl-phenyl-ketone (1-Hydroxy-cyclohexyl-phenyl-ketone, commercially available products are BASF's Irgacure 184), Alternatively, 2-hydroxy-2-methyl-1-phenyl-propanone (2-Hydroxy-2-methyl-1-phenyl-propan-1-one, commercially available as Darocur1173 from BASF) may be used.

More specifically, the photoinitiator is Irgacure 184, Irgacure 819, Irgacure 250 (above, BASF), DIC-F560, Darocur 1173 (above, Ciba), WPI-113, WPI-116, WPI-169, WPI-170 , WPI-124, WPAG-638, WPAG-469, WPAG-370, WPAG-367, WPAG-336 (above, Wako Pure Chemical Industries, Ltd.), B2380, B2381, C1390, D2238, D2248, D2253, I0591, T1608, T1609, T2041, T2042 (above, Tokyo Kasei Industrial Co.), AT-6992, At-6976 (above, ACETO Co.), CPI-100, CPI-100P, CPI101A, CPI-200K, CPI-210S (above, San Apro Co.) , SP-056, SP-066, SP-130, SP-140, SP-150, SP-170, SP-171, SP-172 (above, ADEKA), CD-1010, CD-1011, CD-1012 (Above, Sartomer), San Aid SI-60, SI-80, SI-100, SI-60L, SI-80L, SI-100L, SI-L145, SI-L150, SI-L160, SI-L110, SI-L147 (above, Sanshin Chemical Industry Co., Ltd.), PI2074 (Rhodia Japan Co., Ltd.), etc. can be used. However, the type of the photoinitiator is not limited.

According to an exemplary embodiment of the present invention, the polar organic solvent used in the art may be used without limitation. For example, the polar organic solvent includes at least one of propylene glycol monomethyl ether acetate (PGMEA), 2-butoxyethanol acetate, tetraethylene glycol dimethyl ether and diethylene glycol dibutyl ether can do.

According to an exemplary embodiment of the present invention, the composition for forming the optical substrate may further include an additive including at least one of a release agent, a UV absorber, an antioxidant, a UV stabilizer, a dye, and a pigment.

According to an exemplary embodiment of the present invention, the release agent may be a silicone-based compound or an alkyl phosphate-based compound, but is not limited thereto, and a release agent used in the art may be applied.

According to an exemplary embodiment of the present invention, the UV absorber may be a benzophenone-based compound, a benzotriazole-based compound, or a hydroxyphenyltriazine-based compound, but is limited thereto It is not, and a UV absorber used in the art may be applied.

According to an exemplary embodiment of the present invention, the UV stabilizer may be a hindered amine compound, but is not limited thereto, and UV stabilizers used in the art may be applied.

According to an exemplary embodiment of the present invention, the dye and / or pigment is added to improve the color value of the optical substrate, and dyes and / or pigments used in the art may be applied. For example, when the yellow index value of the initial color of the optical substrate is high, an anthraquinone-based compound, a phthalocyanine-based compound, an indanthren-based compound, or the like can be used as a blue dye. there is.

According to an exemplary embodiment of the present invention, the content of the additive may be 0.1 parts by weight or more and 5 parts by weight or less based on 100 parts by weight of the solid content of the composition for forming an optical substrate. However, it is not limited thereto, and the content of the additive may be appropriately adjusted according to the use of the optical substrate.

An exemplary embodiment of the present invention is a substrate; and a diffraction grating layer provided on one surface of the substrate and including a cured product of the composition for forming the optical substrate. That is, the optical substrate includes a photoreactive monomer including a (meth)acrylate-based compound containing an aromatic group, a photoinitiator, a surfactant, a polar organic solvent, and an inorganic particle having a light refractive index of 2.0 or more at a wavelength of 589 nm. , A diffraction grating layer including a cured product of a composition for forming an optical substrate having a light refractive index of 1.6 or more at a wavelength of 589 nm of a cured product of a photoreactive monomer and a substrate.

Since the optical substrate according to one embodiment of the present invention is lightweight and has excellent optical properties, it can be easily applied as a diffraction light guide plate of a virtual reality device and/or an augmented reality device, and has the advantage of reducing user fatigue. there is.

According to an exemplary embodiment of the present invention, the substrate may be a glass substrate or a plastic substrate, but the type of the substrate is not limited. In addition, when the optical substrate is applied to a diffraction light guide plate for an augmented reality device or a diffraction light guide plate for a virtual reality device, a substrate that does not degrade the optical properties of the diffraction light guide plate may be used without limitation.

According to an exemplary embodiment of the present invention, the optical refractive index of the optical substrate at a wavelength of 589 nm may be 1.75 or more. Specifically, the optical refractive index of the optical substrate at a wavelength of 589 nm may be 1.79 or 1.8 or more. Since the optical substrate having a refractive index of 1.75 or more at a wavelength of 589 nm has excellent optical properties, it has the advantage of being easily applied to a diffraction light guide plate for an augmented reality device or a diffraction light guide plate for a virtual reality device.

According to an exemplary embodiment of the present invention, the haze value of the optical substrate may be 1 or less. Specifically, the haze value of the optical substrate may be 0.5 or less, or 0.3 or less. The optical substrate having a haze value within the aforementioned range has excellent optical properties, and thus has an advantage of being easily applied as a diffraction light guide plate for an augmented reality device or a diffraction light guide plate for a virtual reality device.

The haze of the optical substrate may be measured using a device and/or method for measuring the haze of a member in the art. For example, after positioning the diffraction grating layer of the optical substrate to face the direction of the light source, it can be measured according to JIS K 7105-1 standard using a haze meter (COH400 manufactured by Nippon Denshoku).

According to one embodiment of the present invention, the yellow index value of the optical substrate may be 3 or less. Specifically, the yellow index value of the optical substrate may be 2.9 or less, or 2.7 or less. The optical substrate having a yellow index value within the above range may have excellent optical properties.

The yellow index value of the optical substrate may be measured using a device and/or method for measuring the yellow index of a member in the art. For example, the yellow index value of the optical substrate may be measured according to ASTM standards using a COH400 transmittance meter manufactured by Nippon Denshoku.

According to an exemplary embodiment of the present invention, light transmittance of the optical substrate at a wavelength of visible light may be 85% or more. Specifically, the light transmittance of the optical substrate at a wavelength of visible light may be 89% or more, or 90% or more. An optical substrate having light transmittance at visible light wavelengths within the aforementioned range may be easily used as a diffraction light guide plate for an augmented reality device or a diffraction light guide plate for a virtual reality device.

According to one embodiment of the present invention, the light transmittance of the optical substrate may be measured using a device and/or method for measuring the light transmittance of a member in the art. For example, the light transmittance of the optical substrate at a wavelength of visible light may be measured using COH400 equipment manufactured by Nippon Denshoku.

According to an exemplary embodiment of the present invention, the light refractive index at a wavelength of 589 nm and the light transmittance, yellow index, and haze values at a wavelength of visible light of the optical substrate are measured on Corning's LCD glass (thickness: 0.7 mm) as a substrate. It may be a value measured based on an optical substrate on which the diffraction grating layer is formed to a thickness of 1 μm.

According to an exemplary embodiment of the present invention, one surface of the diffraction grating layer may include a pattern structure, and the pattern structure may include the inorganic particles.

1 is a view schematically showing a cross section of an optical substrate according to an exemplary embodiment of the present invention. Specifically, FIG. 1 shows an optical substrate having a diffraction grating layer 200 on one surface of a substrate 100, and a pattern structure 210 is provided on one surface of the diffraction grating layer 200, and the pattern structure ( 210) may include inorganic particles 300.

According to an exemplary embodiment of the present invention, as the inorganic particles are included in the pattern structure, the optical substrate including the diffraction grating layer can easily implement an optical refractive index of 1.75 or more at a wavelength of 589 nm.

2 is a diagram schematically illustrating a pattern structure according to an exemplary embodiment of the present invention. Specifically, in FIG. 2 , the pattern structure 210 is provided at an inclination angle of θ from one surface of the diffraction grating layer 200, the pattern structure 210 has a height of h, and the pattern structure 210 has a width of d1. It is a view showing that two or more pattern structures 210 are provided with a pitch of d2. In the present invention, “interval” means the interval at which the pattern structure is repeated, and as shown in FIG. 2, the length between a point of one pattern structure 210 and a point of another pattern structure 210 adjacent thereto. can mean A point of one pattern structure 210 and a point of another pattern structure 210 may mean positions corresponding to each other between the pattern structures 210 .

According to an exemplary embodiment of the present invention, the width of the pattern structure may be 100 nm or more and 400 nm or less, and the interval between the pattern structures may be 200 nm or more and 800 nm or less. Specifically, the pattern structure may have a width of 100 nm or more and 300 nm or less, or 150 nm or more and 250 nm or less. In addition, the interval between the pattern structures may be 300 nm or more and 600 nm or less, or 350 nm or more and 450 nm or less.

According to one embodiment of the present invention, a diffraction grating layer including a pattern structure having the width described above can be easily formed using the composition for forming an optical substrate. In addition, the composition for forming the optical substrate has excellent moldability, and thus the interval between the pattern structures can be easily implemented within the above-described range.

Also, each of the plurality of pattern structures included in the diffraction grating layer may have different widths, and intervals between the pattern structures may be differently set according to regions of the diffraction grating layer. In addition, the width of the pattern structure and the interval between the pattern structures may be adjusted according to the specifications of the diffraction light guide plate to which the optical substrate is applied.

According to an exemplary embodiment of the present invention, by adjusting the width of the pattern structure and the distance between the pattern structures to the above range, optical properties such as light refractive index, light transmittance, haze, and yellow index of the optical substrate can be further improved. can Specifically, the light refractive index and light transmittance of the optical substrate at a wavelength of 589 nm can be easily adjusted to appropriate levels for application to a diffraction light guide plate. In addition, since the haze value and the yellow index value of the optical substrate can be effectively reduced, deterioration of optical properties of the optical substrate can be suppressed.

According to an exemplary embodiment of the present invention, the pattern structure may have an inclined pattern inclined at an angle of 50° or more and 90° or less from one surface of the diffraction grating layer. Referring to FIG. 2 , the pattern structure 210 may be provided at an inclination angle θ of 50° or more and 90° or less from one surface of the diffraction grating layer 200 . Also, the height h of the pattern structure 210 may be greater than 0 nm and less than 600 nm. By adjusting the inclination angle of the inclined pattern structure and/or the height of the pattern structure within the above range, an optical substrate that is easily applied to the diffraction light guide plate may be implemented.

In addition, the width of the pattern structure and the interval between the pattern structures may be adjusted according to the specifications of the diffraction light guide plate to which the optical substrate is applied.

3 is a schematic diagram of an optical substrate according to an embodiment of the present invention. Referring to FIG. 3 , a first diffraction area 410, a second diffraction area 420, and a third diffraction area 430 are formed in the diffraction grating layer 200 along a direction from one side to the other side of the diffraction grating layer 200. can be compartmentalized. In addition, the pattern structure 210 may be provided in each of the first diffraction region 410, the second diffraction region 420, and the third diffraction region 430, and the shape of the pattern structure 210 provided in each region. may be different from each other.

According to an exemplary embodiment of the present invention, the optical substrate includes at least a first diffraction area and a third diffraction area among a first diffraction area, a second diffraction area, and a third diffraction area partitioned along a direction from one side to the other side of the diffraction grating layer. area can be included. That is, the diffraction grating layer of the optical substrate may include a first diffraction area and a third diffraction area, and may additionally include a second diffraction area.

Referring to FIG. 3 , the first diffractive region 410 may be a region into which incident light including light having various wavelength values is incident. Also, the second diffraction area 420 is an area in which light incident into the optical substrate is diffracted, and may be an area in which light incident on the first diffraction area 410 is expanded to a third diffraction area 430. The third diffraction area 430 is an area from which light is emitted from the optical substrate, and when the diffraction light guide plate including the optical substrate is used in the display unit, the third diffraction area 430 is adjacent to the eyeball of the user of the display unit. As an area, it may be an area where light is emitted to provide display information to the user.

According to one embodiment of the present invention, the pattern structure may have a height that varies from one side of the diffraction grating layer to the other side. Referring to FIG. 3 , the diffraction grating layer may include a plurality of pattern structures having constant heights and a plurality of pattern structures having gradually changed heights according to regions. In particular, by gradually increasing the heights of the plurality of pattern structures provided in the third diffraction area, light diffraction efficiency may be gradually improved from one side of the third diffraction area to the other side. Through this, when the diffraction light guide plate including the optical substrate is used in a display unit, a user can be provided with image information of a higher quality.

According to an exemplary embodiment of the present invention, the pattern structure may have a duty that changes along a direction from one side of the diffraction grating layer to the other side. In the present invention, “duty” may mean a value obtained by dividing the value of the width of the pattern structure by the interval between the pattern structures (width of the pattern structure/interval between the pattern structures). Referring to FIG. 3 , the duty of the pattern structure may be a value (d1/d2) obtained by dividing the width d1 of the pattern structure by the spacing d2 of the pattern structure.

According to an embodiment of the present invention, the third diffraction region of the diffraction grating layer may include a pattern structure in which duty gradually increases from one side to the other side. Since the third diffraction region of the diffraction grating layer includes a pattern structure having a duty gradually increasing from one side to the other side, light diffraction efficiency may be gradually increased from one side to the other side of the third diffraction region.

According to an exemplary embodiment of the present invention, the duty of the pattern structure may be controlled by adjusting the width of the pattern structure and the interval between the pattern structures. For example, the duty cycle of the pattern structures may be increased by setting the same intervals between the pattern structures and gradually increasing the widths of the pattern structures.

According to one embodiment of the present invention, the duty of the pattern structure may be greater than or equal to 0.1 and less than or equal to 1.0. Specifically, the duty of the pattern structure included in the third diffraction region may be greater than or equal to 0.1 and less than or equal to 1.0. By adjusting the duty ratio of the pattern structure included in the third diffraction region to the above range, an optical substrate that can be easily applied to the diffraction light guide plate can be implemented.

According to an exemplary embodiment of the present invention, the optical substrate may be a diffraction light guide plate for an augmented reality device or a diffraction light guide plate for a virtual reality device. That is, since the optical substrate has excellent optical properties such as optical refractive index, light transmittance, haze, and yellow index and is lightweight, it is easy to apply as a diffraction light guide plate for an augmented reality device or a diffraction light guide plate for a virtual reality device.

Hereinafter, examples will be described in detail to explain the present invention in detail. However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention is not construed as being limited to the embodiments described below. The embodiments herein are provided to more completely explain the present invention to those skilled in the art.

Example One

Preparation of a composition for forming an optical substrate

As photoreactive monomers, dibenzo[b,d]furan-3-ylmethyl acrylate, a (meth)acrylate-based compound represented by Formula 1, and dibenzo[b,d], a (meth)acrylate-based compound represented by Formula 2 above ] Prepare M1082 (Miwon Specialty Co.) mixed with furan-3,7-diylbis (methylene) diacrylate, Darocur 1173 (Ciba Co.) as a photoinitiator, DIC-F560 (Megaface Co.) as a fluorine-based surfactant, and zirconia as inorganic particles (ZrO ₂ ) and 2-butoxyethanol acetate as a solvent were mixed in a weight ratio of 1:1 to prepare PCPG-50-BCA (Pixelligent Co.).

At this time, the cured product obtained by curing only the photoreactive monomer had a light refractive index of about 1.65 at a wavelength of 589 nm. In addition, the zirconia (ZrO ₂ ) had an optical refractive index of 2.1 at a wavelength of 589 nm and an average diameter of 8 nm.

Thereafter, a composition for forming an optical substrate was prepared by mixing prepared M1082, Darocur 1173, DIC-F560, and PCPG-50-BCA.

At this time, the solid content of the prepared composition for forming an optical substrate was about 54% by weight. In addition, with respect to 100 parts by weight of solid content, the content of zirconia, which is an inorganic particle, is about 85.3 parts by weight, the content of photoreactive monomer is about 11.4 parts by weight, the content of photoinitiator is about 2.8 parts by weight, and the content of fluorine-based surfactant is about 0.5 parts by weight. It was wealth.

Manufacture of optical substrates

LCD glass (Corning Co., Ltd.) having a thickness of 0.7 mm was prepared as a substrate, and the composition for forming an optical substrate was applied to a thickness of about 1 μm on the glass substrate, and dried at a temperature of 80 ° C. for about 3 minutes. . Thereafter, the pattern of the diffraction grating layer set in advance was imprinted on the surface of the composition for forming a substrate for optical use on the substrate using an intaglio mold. In the process of imprinting, ultraviolet rays having an intensity of 100 mw/cm ² or more at a temperature of about 40° C. are irradiated for 60 seconds or more to photo-cur the composition for forming a substrate for optical use, so that the diffraction grating layer is provided on the substrate. A substrate was prepared.

At this time, referring to FIG. 2, in the diffraction grating layer of the optical substrate manufactured, the width (d1) of the pattern structure is about 202.5 nm, the interval (d2) between the pattern structures is about 405 nm nm, and the height (h) of the pattern structure was about 200 nm, and the slope (Θ) of the patterned structure was about 35° nm.

4 is a photograph taken using a scanning electron microscope of a cross section of an optical substrate prepared in Example 1 of the present invention. Referring to FIG. 4 , it was confirmed that inorganic particles were included in the pattern structure of the diffraction grating layer prepared in Example 1.

That is, according to an exemplary embodiment of the present invention, as inorganic particles are included in the pattern structure of the diffraction grating layer, the optical substrate including the diffraction grating layer can easily implement an optical refractive index of 1.75 or more at a wavelength of 589 nm. Able to know.

Example 2 and Example 3

As shown in Table 1 below, a composition for forming an optical substrate was prepared in the same manner as in Example 1, except that the contents of zirconia, photoreactive monomer, photoinitiator, and fluorine-based surfactant were adjusted with respect to 100 parts by weight of solid content, , A substrate for optics was prepared using this.

inorganic particles
(parts by weight) photoreactive monomer
(parts by weight) photoinitiator
(parts by weight) Surfactants
(parts by weight) Example 1 ZrO ₂ (85.3) M1082
(11.4) DIC-F560
(2.8) Darocur 1173 (0.5) Example 2 ZrO ₂ (77.3) M1082
(19.4) DIC-F560
(2.8) Darocur 1173 (0.5) Example 3 ZrO ₂ (80.3) M1082
(16.4) DIC-F560
(2.8) Darocur 1173 (0.5)

In Table 1, the contents of the inorganic particles, photoreactive monomers, photoinitiators, and fluorine-based surfactants are based on 100 parts by weight of solid content.

comparative example One

As shown in Table 2 below, a composition for forming an optical substrate was prepared in the same manner as in Example 1, except that the contents of zirconia, photoreactive monomer, photoinitiator, and fluorine-based surfactant were adjusted with respect to 100 parts by weight of solid content, , A substrate for optics was prepared using this.

5 is a photograph taken with a digital camera of the optical substrate prepared in Comparative Example 1 of the present invention. Referring to FIG. 5 , it can be seen that the content of inorganic particles in the optical substrate of Comparative Example 1 is low, so that the monomers and the inorganic particles are not homogeneously mixed and the monomers are not aggregated to form a uniform coating film.

comparative example 2

Titanium dioxide (DT-TIOA-N10, Dito Technology Co., Ltd.) was used as an inorganic particle, and the contents of titanium dioxide, photoreactive monomer, photoinitiator, and fluorine-based surfactant were adjusted with respect to 100 parts by weight of the solid content as shown in Table 1 below. Except for the above, a composition for forming a substrate for optics was prepared in the same manner as in Example 1, and a substrate for optics was prepared using the same.

The titanium dioxide had an optical refractive index of 2.5 at a wavelength of 589 nm and an average diameter of 10 nm.

inorganic particles
(parts by weight) photoreactive monomer
(parts by weight) photoinitiator
(parts by weight) Surfactants
(parts by weight) Comparative Example 1 ZrO ₂ (67.6) M1082
(29.1) DIC-F560
(2.8) Darocur 1173 (0.5) Comparative Example 2 TiO ₂ (74) M1082
(22.7) DIC-F560
(2.8) Darocur 1173 (0.5)

Evaluation of physical properties of optical substrates

With respect to the optical substrates prepared in Examples 1 to 3 and Comparative Examples 1 to 2, the optical refractive index, light transmittance, yellow index and haze of the optical substrate were measured using the method described above, and the results It is shown in Table 3 below.

optical refractive index light transmittance yellow index haze Example 1 1.7960 89.05 0.93 0.36 Example 2 1.7514 89.39 1.07 0.37 Example 3 1.8127 89.43 0.97 0.38 Comparative Example 1 1.7279 89.79 0.95 0.35 Comparative Example 2 1.8619 88.06 4.33 2.13

As shown in Table 3, it can be seen that the optical substrates of Examples 1 to 3 have optical refractive index of 1.75 or more, excellent light transmittance, and excellent optical properties from low haze and yellow index values.

In contrast, it was confirmed that the optical substrate of Comparative Example 1 having an inorganic particle content of less than 75 parts by weight had a small light refractive index and had poor optical properties. In addition, it was confirmed that the optical properties of the optical substrate of Comparative Example 2, in which the inorganic particles were TiO ₂ and the content thereof was less than 75 parts by weight, had a high yellow index value, and thus did not have excellent optical properties.

Therefore, it can be seen that the optical substrate according to the present invention has excellent optical properties. In addition, it can be seen that the composition for forming an optical substrate according to the present invention can implement an optical substrate having excellent optical properties.

100: substrate
200: diffraction grating layer
210: pattern structure
300: inorganic particles
410 first diffraction region
420: second diffraction region
430 third diffraction region

Claims (16)

A photoreactive monomer including a (meth)acrylate-based compound containing an aromatic group; photoinitiators; Surfactants; polar organic solvents; And inorganic particles having a light refractive index of 2.0 or more at a wavelength of 589 nm;
The cured product of the photoreactive monomer has an optical refractive index of 1.6 or more at a wavelength of 589 nm,
The inorganic particles are included in an amount of 75 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of solid content,
The photoreactive monomer is contained in an amount of 10 parts by weight or more and 15 parts by weight or less based on 100 parts by weight of solid content, the composition for forming an optical substrate.
delete The method of claim 1,
The surfactant is included in an amount of 2 parts by weight or more and 5 parts by weight or less based on 100 parts by weight of solid content.
The method of claim 1,
The photoinitiator is a composition for forming an optical substrate included in an amount of 0.1 parts by weight or more and 1 part by weight or less based on 100 parts by weight of solid content.
The method of claim 1,
A composition for forming an optical substrate wherein the weight ratio of the photoreactive monomer to the inorganic particles is 1:3 to 1:9.
The method of claim 1,
The composition for forming an optical substrate having a diameter of 25 nm or less of the inorganic particles.
write; and
An optical substrate comprising a diffraction grating layer provided on one surface of the substrate and including a cured product of the composition for forming an optical substrate according to claim 1 .
The method of claim 7,
An optical substrate having an optical refractive index of 1.75 or more at a wavelength of 589 nm.
The method of claim 7,
An optical substrate having a haze value of 1 or less.
The method of claim 7,
An optical substrate having a yellow index value of 3 or less.
The method of claim 7,
One side of the diffraction grating layer includes a pattern structure, and the pattern structure includes the inorganic particles.
The method of claim 11,
The width of the pattern structure is 100 nm or more and 400 nm or less, and the interval between the pattern structures is 200 nm or more and 800 nm or less.
The method of claim 11,
The pattern structure is an optical substrate having an inclined pattern inclined at an angle of 50 ° or more and 90 ° or less from one surface of the diffraction grating layer.
The method of claim 11,
The pattern structure is an optical substrate in which a height is changed along a direction from one side to the other side of the diffraction grating layer.
The method of claim 11,
The pattern structure is an optical substrate whose duty is changed along a direction from one side to the other side of the diffraction grating layer.
The method of claim 7,
The optical substrate is a diffraction light guide plate for an augmented reality device or a diffraction light guide plate for a virtual reality device.