WO2010018937A2 - Coating formulation affording antireflection effects on transparent substrate and method for manufacturing transparent substrate with antireflection function using said coating formulation - Google Patents

Abstract

The present invention provides a method for preparing a glass substrate with antireflection functionality by applying a coating formulation that affords antireflection effects to a substrate comprising water, metalloid oxide nanoparticles that are dispersed in said water, and a hydroxide ion agent or fluoride ion agent that is introduced into said metalloid oxide nanoparticles at a mole ratio of 0.005-2:1. The coating formulation of the present invention enables manufacture of a porous nano antireflection film with high transmission following a more streamlined process than the prior art, obtaining an antireflection film with a high adhesive force between the film and substrate, and high durability by increasing particle-particle bonding and the bond strength between particles and substrate.

Description

Method for producing a transparent substrate having an antireflection function by using a coating composition that gives an antireflection effect to the transparent substrate and the coating composition

The present invention relates to a coating composition for imparting an antireflection effect to a transparent substrate and a method for producing a transparent substrate having an antireflection function using the composition.

When watching TV in a bright outside environment, it's common to see a blurred image due to reflected images. This is because glass and optical resins used for glasses and displays do not show 100% light transmittance and have a considerable amount of reflectance. Therefore, in order to maintain the image resolution of the optical transparent substrate, antireflection (AR) technology is widely employed to reduce reflectance and increase light transmittance by surface treatment of the transparent substrate. Such AR technology can be usefully used for optical devices such as telescopes, glasses, optical communication parts, optoelectronic devices, solar devices, and display parts.

Antireflection technology by surface treatment of a transparent substrate can be largely divided into a technique of etching the surface in a fine pattern and AR coating technology to give a porous coating on the surface.

The fine pattern etching method is a method of forming a fine concavo-convex pattern on the surface of the substrate by performing a non-uniform etching of the substrate using a wet or plasma method.

AR coating technology has been used for four years since Geffken applied for three layers of AR coatings in 1940. U.S. Patent 5856018 discloses a four-layer coating technique of SiO2 / TiO2 / SiO2 / TiO2 applied on a polymethyl methacrylate as a substrate. Korean Patent Application No. 10-1994-0036298 discloses a reflection reducing coating in which a high refractive index layer, a low refractive index layer and an uneven low refractive index layer are sequentially stacked. As such, the conventional antireflective coating consists of at least two to four layers of multi-layer coatings such as TiO2 / SiO2, SiO2 / TiO2 / SiO2, TiO2 / SiO2 / TiO2 / SiO2. Uneasy. In particular, the TiO2 layer has a stacking thickness of 15 nm to 30 nm, which is applied as a very thin layer, and is very sensitive to moisture, resulting in many defect rates.

Therefore, since the fine pattern etching method or the multilayer coating method is complicated and it is not easy to control the quality, the manufacturing cost is increased.

By the Frisnel equation, the following conditions can be obtained.

If the refractive index of the substrate is n _t = 1.52, such as glass, and AR coating has n ₁ = 1.23 and a thickness of 1/4 of the wavelength, the material has a low refractive index close to 0% in the visible region. In order to convert a material with a refractive index of 1.52 to a material with a refractive index of 1.23, pores should be made using the following equation derived from the relationship between density and refractive index.

If the refractive index is 1.52 (n value) and the porosity (P value) is 60%, the refractive index is approximated to 1.23 (n _p value). If the pore size is similar to the wavelength of light, the coating layer becomes opaque due to light scattering, so the pore size should be several hundred nanometers or less smaller than the wavelength of light.

In the porous monolayer coating method, a mixture of silica sol and a polymer binder is coated on a substrate, and then the polymer component is removed by extraction or calcination to form pores or the substrate is coated with two polymer mixtures. There is a known method of extracting pores. However, there may be a problem in terms of environment, because a high temperature firing process or a complicated process of extracting the solvent and a toxic solvent should be used.

The present invention is to provide a coating composition that is applied as a single layer coating layer inexpensively giving an antireflection effect to the transparent substrate.

In addition, the present invention is to provide a method for producing a transparent substrate having an antireflection function that can be easily applied to a large area transparent substrate and is economically performed.

According to the present invention, a reflection on a transparent substrate made of water, a metal hydroxide nanoparticle dispersed in the water, and a hydroxide ion providing agent or a fluorine ion providing agent introduced at a molar ratio of 0.005 to 2: 1 relative to the metalloid nanoparticles. A coating composition is provided that imparts a protective effect.

In addition, according to the present invention, the step of cleaning the transparent substrate surface; Water, the metalloid nanoparticles dispersed in the water on the surface of the transparent substrate and the coating composition consisting of a hydroxide ion providing agent or a fluorine ion providing agent added in a molar ratio of 0.005 to 2: 1 relative to the metalloid nanoparticles Coating a coating; And there is provided a method for producing a transparent substrate having an antireflection function consisting of a step of drying. If necessary, washing and drying may be repeated after drying.

The metalloid oxide nanoparticles are preferably metalloid oxide nanoparticles selected from the group consisting of silica, alumina, titania, magnesia, ceria, zinc oxide, indium oxide, tin oxide and mixtures thereof, and the transparent substrate. May also comprise transparent plastics but are generally metalloid oxides or transparent substrates coated with them, preferably silica, alumina, titania, magnesia, ceria, zinc oxide, indium oxide, tin oxide and mixtures thereof Metallurgical metal, glass or a transparent substrate coated with the metalloid oxide or glass selected from the group consisting of, most preferably, glass.

The coating composition is optionally applied to the glass substrate within 30 days, or optionally within 24 hours after the hydroxide or fluorine ion donor is added. When the concentration of the hydroxide ion providing agent or the fluorine ion providing agent is relatively high, the gelation or dissolution of the nano silica particles may occur within 24 hours depending on the PH, which may make it difficult to use.

The coating composition may further include an organic solvent having a low surface tension such as methanol or ethanol and / or a surfactant as a surface tension reducing agent. The organic solvent is 10% to 90% by weight, preferably 20 to 40% by weight of the total coating composition.

The metalloid oxide nanoparticles are preferably 1 to 10% by weight based on the total weight of the coating composition, and the metalloid oxide nanoparticles have a particle diameter of 1 to 800nm, preferably 5 to 100nm. Quasi-metal oxide nanoparticles of 5 nm or less are difficult to manufacture, and semi-metal oxide nanoparticles having a size of 100 nm or more may exhibit a decrease in transmittance due to scattering.

The hydroxide ion donor may be an inorganic hydroxide or an organic hydroxide, various kinds of hydroxides may be used, and preferably ammonium hydroxide (NH ₄ OH). At this time, for obtaining a stable and adequate bonding force between the particles in the case of the silica nanoparticle solution _{^{[OH -] / [SiO 2}} ] , the molar ratio is preferably from 0.05 to 2.0, most preferably having from 0.1 to 0.5 mole ratio Do.

The fluorine ion providing agent, Preferably, hydrofluoric acid, silicic hexafluoride (H₂SiF₆) Or salts thereof, and most preferably KF or ammonium fluoride (NH).₄F). At this time, in the case of silica nanoparticles [F to obtain an appropriate bonding force between the particles^-, HF₂                     ^-] / [SiO₂] Molar ratio is preferably 0.005 to 1.0, most preferably 0.01 to 0.5. The pH of the solution should preferably be maintained at least 8.5.

The coating composition is coated on the substrate by a method such as spray coating, spin coating, dip coating, slot die coating or the like. The coating composition may be coated on a substrate, if necessary, in multiple layers. At this time, the further the layer away from the substrate, the larger the porosity of the nanoparticles constituting the layer. In addition, if necessary, the surface hardness of the antireflection film by applying a perfluoroalkyl (alkoxy) silane or a perfluoropolyether or derivatives thereof substituted with functional groups of alcohol, silane, acetic acid, amine, halogen on the antireflection substrate In addition to the increase in the high permeability can be maintained for a long time.

The mechanism of bonding between nanoparticles or between nanoparticles and a substrate is described below using silica nanoparticles and a glass substrate as an example. This mechanism is so presumed and the invention is not necessarily limited thereto. The hydroxyl ion donor used in the present invention is presumed to be partially dissolved by the following reaction with the surface of the nano silica particles and the base glass.

^{_{1) SiO 2 + OH - +}} 2H 2 O ----> Si (OH) 5 -

When the coating composition containing the hydroxide ion-providing agent of the present invention is coated on a glass substrate and dried, it is assumed that the following reaction occurs, and a hard bond is formed between the silica nanoparticles or between the silica nanoparticles and the glass substrate surface.

2) Nanoparticles-Si-OH + HO-Si-nanoparticles-> Nanoparticles-Si-O-Si-nanoparticles + H ₂ O

3) Nanoparticles-Si-OH + HO-Si-Glass Surface-> Nanoparticles-Si-O-Si-Glass Surface + H ₂ O

The fluorine ion donor used in the present invention is presumed to be partially dissolved by the following reaction with the surface of the nano silica particles and the base glass.

4) SiO ₂ + 6F ^_ + 6H ⁺ -----> H ₂ SiF ₆ + 2H ₂ O

When the coating composition containing the fluorine ion-providing agent of the present invention is coated on a glass substrate and dried, it is assumed that the following reaction occurs, and a solid bond is formed between the silica nanoparticles or between the silica nanoparticles and the glass substrate surface.

5) Nanoparticles-Si-F + HO-Si-nanoparticles ----> Nanoparticles-Si-O-Si-nanoparticles + HF

6) Nanoparticles-Si-F + HO-Si-Glass Surface ----> Nanoparticles-Si-O-Si-Glass Surface + HF

The coating composition of the present invention can produce a nanoporous anti-reflective film having a high transmittance even with a simplified process compared to the prior art, and has a high adhesive strength between the membrane and the substrate and high durability by increasing the bonding between the particles and particles and the particles and the substrate. An antireflection film can be obtained.

1 is a graph showing the transmittance of a substrate when an antireflection film is formed according to Example 20 of the present invention and when no antireflection treatment is performed (Comparative Example 2).

2 is a graph showing the transmittance of the substrate when the antireflection film according to Example 21 of the present invention is formed on the ITO glass substrate and when it is not (Comparative Example 3).

<Example 1>

55 mL of distilled water was added to 45 mL of a 10 wt% solution of colloidal silica (Ace Hitec, Silifog) having an average particle size of 6 nm, and then treated with an ultrasonic disperser for about 30 minutes to prepare a silica dispersion having a concentration of 4.5 wt%. 0.14 g of NH ₄ F was added to the dispersion, and a molar ratio of [NH ₄ F] / [SiO ₂ ] was set at 0.05 to about 30 minutes using an ultrasonic disperser to prepare a coating composition. The coating composition was prepared in order to observe the gelation, pH and size of the silica particles. After the preparation, the pH of the solution and the size of the silica particles were continuously measured for 15 days. Measured using.

After washing the soda-lime glass well with detergent, it was immersed in 1M KOH solution for 5 hours and then washed with distilled water to blow air to dry to avoid water marks. 12 hours after the preparation of the coating composition, the soda-lime glass was coated at a speed of 800 rpm at 20 ^° C. and 20% relative humidity by spin coating to prepare a silica coating film, and then dried at 120 ^° C. for 3 hours. It was.

The transmittance and reflectance of the produced sample were measured by Shimadzu UV-3100PC spectrophotometer. The hardness of the anti-reflection film was measured by a pencil hardness tester using the standard method of ASTM D3360-00, and the adhesion of the anti-reflection film was performed by the scotch tape test according to the standard method of ASTM D3359. Measured physical properties are summarized in Table 1.

Comparative Example 1

The same method as in Example 1 was carried out except that the silica dispersion without NH ₄ F was used as the coating composition. Measured physical properties are summarized in Table 1.

<Examples 2-4>

NH ₄ F in Examples 2 to 4 was carried out as in Example 1 except that 0.27g, 0.55g and 1.11g were used, respectively. However, the coating composition was not performed when the gelation or the particle size of the nano silica particles were reduced within 12 hours after preparation. Measured physical properties are summarized in Table 1.

<Examples 5-8>

Examples 5 to 8 are the same as in Example 1 except that 0.08g (equivalent to 0.007 molar ratio), 0.18g, 0.35g and 0.72g (equivalent to 0.066 molar ratio) of H ₂ SiF ₆ is used instead of NH ₄ F, respectively. Was performed. However, the coating composition was not performed when the gelation or the particle size of the nano silica particles were reduced within 12 hours after preparation. Measured physical properties are summarized in Table 1.

<Examples 9-12>

Examples 9 to 10 were carried out as in Example 1 except for using 0.21 g, 0.42 g, 0.84 g and 1.68 g KOH instead of NH ₄ F, respectively. However, the coating composition was not performed when the gelation or the particle size of the nano silica particles were reduced within 12 hours after preparation. Measured physical properties are summarized in Table 1.

<Examples 13 and 14>

Examples 13 and 14 were respectively coated in the thin film samples prepared in Examples 3 and 4 by diluting Solvay's perfluoropolyether solution to 0.3 wt% in Galden ZV-130 solvent to spin coating to a thickness of about 2-5 nm. After coating using the method was carried out by drying for 1 hour at 120 ^° C. The surface hardness of the membrane was measured by a pencil hardness tester using the standard method of ASTM D3360-00, and the hardness values were summarized in Table 2, and it was confirmed that the H value was increased by one step without loss of transmittance.

<Example 15>

55 mL of distilled water was added to 45 mL of a 10 wt% solution of colloidal silica (Ace Hitec, Silifog) having an average particle size of 6 nm, and then treated with an ultrasonic disperser for about 30 minutes to prepare a silica dispersion having a concentration of 4.5 wt%. 0.3 g of NH ₄ F was added to the dispersion and treated with an ultrasonic disperser for about 30 minutes to prepare a coating composition.

After washing the soda-lime glass well with detergent, it was immersed in 1M KOH solution for 4-6 hours and washed with distilled water to blow air to dry to avoid water marks. Here, the coating composition prepared above was applied at a speed of 800 rpm at 20 ^° C. and 20% relative humidity by spin coating to prepare a silica coating film, and then dried at 120 ^° C. for 3 hours.

The transmittance and reflectance of the produced sample were measured by Shimadzu UV-3100PC spectrophotometer. The hardness of the anti-reflection film was measured by a pencil hardness tester using the standard method of ASTM D3360-00, and the adhesion of the anti-reflection film was performed by the scotch tape test according to the standard method of ASTM D3359. Measured physical properties are summarized in Table 3.

<Examples 16-19>

The average particle size of the silica particles was performed in the same manner as in Example 15 except that the average particle sizes of the silica particles were 15, 20, and 40 nm (Ace Hitech, Silifog) and 120 nm (Evonik, Aerodisp), respectively. The characteristics of this antireflection film are summarized in Table 3.

Comparative Example 2

After washing the soda-lime glass well with detergent, it was immersed in 1M KOH solution for 5 hours and then washed with distilled water to blow air to dry to avoid water marks. There was no antireflection film treatment. The rest was performed in the same manner as in Example 1, and its transmittance is represented by an A curve in FIG. 1 around the visible light region.

Example 20

Except for forming a coating film on the back surface of the soda-lime glass prepared in the same manner as in Example 1 to form an anti-reflection film on both sides was carried out in the same manner as in Example 1 and its transmittance is centered in the visible region It is shown by the B curve at 1. In Comparative Example 2, in which the antireflection film was not formed, the transmittance percentage showed a maximum improvement of 10%.

Comparative Example 3

The glass specimen coated with indium tin oxide (ITO) was ultrasonically cleaned with ethanol and secondary distilled water for 20 minutes, and then treated with oxygen plasma (at which the partial pressure of oxygen was 0.2 Torr and the RF output was 100 W for 3 minutes). Of contaminants was removed. It was carried out as in Example 1 except that the glass substrate coated with the oxygen plasma treated indium tin oxide (ITO) coated instead of the soda-lime glass was not treated with the anti-reflective coating. Its transmittance is shown by the curve C in FIG. 2 around the visible light region.

 Example 21

Instead of soda-lime glass, the glass specimen coated with indium tin oxide (ITO) was ultrasonically cleaned for 20 minutes with ethanol and secondary distilled water, and then treated with oxygen plasma to remove contaminants on the surface (wetness of ITO surface). In this case, the method of Example 1 was performed except that the partial pressure of oxygen was 0.2 Torr and the RF output was 100 W for 3 minutes). The pencil hardness of the antireflection film was 3H. The transmittance of the sample coated with the silica anti-reflection film on one surface of the ITO side was increased by about 5% compared to the ITO glass substrate without the anti-reflection film, and its transmittance is represented by the D curve of FIG. 2 around the visible light region. The resistance change of the ITO thin film could not be observed.

Table 1 Composition of Coating Solution and Properties of Solution and Anti-reflection Film

	Furtherance		Properties
number	catalyst	Concentration (wt%)	Solution stability	Transmittance	Pencil hardness
Comparative Example 1	No addition	-	No change for 15 days	94%	HB
Example 1	NH 4 F	0.14	No change for 15 days	94.2%	2H
Example 2		0.27	No change for 15 days	94.4%	3H
Example 3		0.55	Gelation within 24 hours	92.5%	4H
Example 4		1.11	Gel within 3 hours	-	-
Example 5	H 2 SiF 6	0.08	No change for 15 days	93.5%	2H
Example 6		0.18	No change for 15 days	94%	2H
Example 7		0.35	Gel within 8 hours	-	-
Example 8		0.72	Gel within 3 hours	-	-
Example 9	KOH	0.21	No change for 15 days	93%	2H
Example 10		0.42	No change for 15 days	93%	2H
Example 11		0.84	No change for 15 days	-	-
Example 12		1.68	Silica dissolved	-	-

TABLE 2 Perfluoropolyether additional coating

number	Transmittance	Pencil hardness
Example 13	94.3%	4H
Example 14	92.6%	5H

TABLE 3 Characteristics of Anti-reflection Film According to Particle Size

number	Size (nm)	Hardness	Permeability (%)
Example 15	6	3H	94.5
Example 16	15	3H	94.2
Example 17	20	2H	94.1
Example 18	40	2H	93.0
Example 19	120	HB	92.2

AR technology using the present invention can be usefully used for optical devices such as telescopes, glasses, optical communication components, optoelectronic devices, solar devices and display parts.

Claims (15)

1. It provides an antireflection effect to a transparent substrate made of water, a metal hydroxide nanoparticle dispersed in the water and a hydroxide ion providing agent or a fluorine ion providing agent in a molar ratio of 0.005 to 2: 1 relative to the metalloid nanoparticles. Coating Composition
2. The method of claim 1, wherein the metalloid oxide nanoparticles are nanoparticles of metalloids selected from the group consisting of silica, alumina, titania, magnesia, ceria, zinc oxide, indium oxide, tin oxide and mixtures thereof. The transparent substrate is an antireflective effect on a transparent substrate which is a metalloid, glass or a substrate coated with silica, alumina, titania, magnesia, ceria, zinc oxide, indium oxide, tin oxide and mixtures thereof. Coating composition
3. The coating composition of claim 2, wherein the semimetal oxide nanoparticles are silica nanoparticles and the transparent substrate is glass.
4. The coating composition of claim 1, wherein the coating composition further comprises 10 wt% to 90 wt% of methanol or ethanol as a surface tension reducing agent.
5. The coating composition of claim 1, wherein the coating composition is applied to a glass substrate within 30 days after the hydroxide ion providing agent or the fluorine ion providing agent is added.
6. According to claim 1, wherein the nano silica in the coating composition is 1 to 10% by weight based on the total weight of the coating composition, the nano silica is a coating composition to impart an antireflection effect to a transparent substrate having a particle diameter of 5 ~ 100m
7. 6. The method of claim 5, provided ion the hydroxide in the coating composition of claim hydroxide ammonium (NH ₄ OH) and _{^{[OH -] / [SiO 2}} ] , the molar ratio is given the anti-reflection effect in the range of 0.05 to 2 transparent substrate of the Coating composition
8. The method of claim 5, wherein the fluorine ion providing agent in the coating composition is hydrofluoric acid, hexafluorosilicate (H₂SiF₆) Or salts thereof [F^-, HF₂                 ^-] / [SiO₂], The coating composition imparting the antireflection effect to the transparent substrate of 0.005 to 1.0
9. Cleaning the transparent substrate surface; A coating comprising a hydroxide ion providing agent or a fluorine ion providing agent introduced at a molar ratio of 0.005 to 2: 1 to water, the metalloid oxide nanoparticles dispersed in the water, and the metalloid nanoparticles dispersed on the surface of the transparent substrate. Coating the composition; And Method for producing a transparent substrate having an antireflection function consisting of a step of drying
10. 10. The method according to claim 9, wherein the metalloid oxide nanoparticles are metalloid oxide nanoparticles selected from the group consisting of silica, alumina, titania, magnesia, ceria, zinc oxide, indium oxide, tin oxide and mixtures thereof. The substrate is a transparent substrate having an antireflection function, which is a metalloid, glass or a substrate coated with silica, alumina, titania, magnesia, ceria, zinc oxide, indium oxide, tin oxide and mixtures thereof. Manufacturing Method
11. 10. The method of claim 9, wherein the metalloid oxide nanoparticles are silica nanoparticles and the transparent substrate is glass.
12. 10. The method of claim 9, further comprising applying perfluoroalkyl (alkoxy) silane, perfluoropolyether or derivatives thereof.
13. The method of claim 10, wherein the coating composition has an antireflection function applied to a glass substrate within 30 days after the hydroxide ion providing agent or the fluorine ion providing agent is added.
14. The method according to claim 11, wherein the nano silica in the coating composition is 1 to 10% by weight based on the total weight of the coating composition, the nano silica has a particle diameter of 5 to 100 nm and the hydroxide ion providing agent is ammonium hydroxide (NH ₄ OH), and ^- the method of / [SiO _2] molar ratio of transparent substrates having an antireflection function in the 0.5 to 1.2 [OH]
15. The method of claim 12, wherein the nano-silica in the coating composition is 1 to 10% by weight based on the total weight of the coating composition, the nano-silica has a particle diameter of 5 to 100 nm and the fluorine ion providing agent is hydrofluoric acid, hexafluorosilicate ( H₂SiF₆) Or salts thereof [F^-, HF₂                 ^-] / [SiO₂] Molar ratio is 0.005 to 1.0 method of manufacturing a transparent substrate having an antireflection function

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