Anti-reflective coating composition comprising siloxane compound, and anti-reflective film using same

Abstract

The present invention relates to an anti-reflective coating composition, to an anti-reflective film using the same, and to a method for manufacturing the anti-reflective film, wherein the anti-reflective coating composition can form a coating layer having a low refractive index. More particularly, the present invention relates to an anti-reflective film and to a method for manufacturing same, wherein the reflectance of the anti-reflective film is minimized by using an anti-reflective coating composition comprising a siloxane compound prepared by reacting organosilane, which has a fluoroalkyl group and alkoxy silane, as a binder to form a coating layer. The anti-reflective film using the anti-reflective coating composition has excellent anti-reflective effects. Thus, it is expected that the present invention can be applied to various display devices such as those which include touch films.

Claims

1. An anti-reflective coating composition comprising: a binder formed by polymerization of a silane compound represented by Formula 1 and an organosilane compound represented by Formula 2, wherein the organosilane compound represented by Formula 2 is present in an amount of 1 part by weight to 30 parts by weight, based on 100 parts by weight of the silane compound represented by Formula 1, and wherein the binder has a weight average molecular weight from 12,000 to 18,000; hollow silica particles; and an acid catalyst configured to promote a surface treatment of the hollow silica by the binder, wherein the acid catalyst is present in an amount of 0.1 part by weight to 20 parts by weight based on 100 parts by weight of the hollow silica particles, wherein the coating composition has a pH in the range of 2 to 4
R.sup.1.sub.xSi(OR.sup.2).sub.4-x[Formula 1] wherein R.sup.1 is a C.sub.1 to C.sub.10 alkyl group, a C.sub.6 to C.sub.10 aryl group, or a C.sub.3 to C.sub.10 alkenyl group; R.sup.2 is a C.sub.1 to C.sub.6 alkyl group; and x is an integer satisfying 0x3
R.sup.3.sub.ySi(OR.sup.4).sub.4-y[Formula 2] wherein R.sup.3 is a C.sub.1 to C.sub.12 fluoroalkyl group; R.sup.4 is a C.sub.1 to C.sub.6 alkyl group; and y is an integer satisfying 0y3.

2. The coating composition according to claim 1, wherein the silane compound represented by Formula 1 comprises at least one compound selected from among tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, trimethoxysilane, triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isobutyltriethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane.

3. The coating composition according to claim 1, wherein the organosilane compound represented by Formula 2 comprises at least one compound selected from among trifluoromethyltrimethoxysilane, trifluoromethyltriethoxysilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, nonafluorobutylethyltrimethoxysilane, nonafluorobutyl ethyltriethoxysilane, nonafluorohexyltrimethoxysilane, nonafluorohexyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, and heptadecafluorodecyltriethoxysilane.

4. The coating composition according to claim 1, wherein x of Formula 1 is an integer of 0, 1 or 2.

5. The coating composition according to claim 1, wherein R.sup.3 of Formula 2 is a C.sub.3 to C.sub.5 fluoroalkyl group.

6. The coating composition according to claim 1, wherein the hollow silica particles have a number average diameter from 1 nm to 1,000 nm.

7. The coating composition according to claim 1, wherein the binder is present in an amount of 10 parts by weight to 120 parts by weight based on 100 parts by weight of the hollow silica particles.

8. An anti-reflective film comprising a low index of refraction layer formed by coating the coating composition according to claim 1 onto a surface of a base.

9. The anti-reflective film according to claim 8, wherein the low index of refraction layer has an index of refraction from 1.20 to 1.25.

10. The anti-reflective film according to claim 8, wherein the low index of refraction layer has a thickness of 1 nm to 1,000 nm.

11. The anti-reflective film according to claim 8, wherein the anti-reflective film has a transmittance of 96% or more and a luminous reflectance from 0.5% to 1.0%.

12. A touch panel comprising the anti-reflective film according to claim 8.

13. A method for manufacturing an anti-reflective film, comprising: preparing a binder by polymerization of a silane compound represented by Formula 1 and an organosilane compound represented by Formula 2, wherein the organosilane compound represented by Formula 2 is present in an amount of 1 part by weight to 30 parts by weight, based on 100 parts by weight of the silane compound represented by Formula 1, and wherein the binder has a weight average molecular weight from 12,000 to 18,000; preparing a coating composition comprising surface-treated hollow silica particles by adding the binder and an acid catalyst to the hollow silica, wherein the acid catalyst is configured to promote a surface treatment of the hollow silica particle by the binder, wherein the acid catalyst is present in an amount of 0.1 part by weight to 20 parts by weight, based on 100 parts by weight of the hollow silica particles; coating the coating composition onto at least one surface of a base film; and performing heat treatment of the coated coating composition, wherein the acid catalyst is configured to adjust the coating composition to a pH value in the range of 2 to 4
R.sup.1.sub.xSi(OR.sup.2).sub.4-x[Formula 1] wherein R.sup.1 is a C.sub.1 to C.sub.10 alkyl group, a C.sub.6 to C.sub.10 aryl group, or a C.sub.3 to C.sub.10 alkenyl group; R.sup.2 is a C.sub.1 to C.sub.6 alkyl group; and x is an integer satisfying 0x3
R.sup.3.sub.ySi(OR.sup.4).sub.4-y[Formula 2] wherein R.sup.3 is a C.sub.1 to C.sub.12 fluoroalkyl group; R.sup.4 is a C.sub.1 to C.sub.6 alkyl group; and y is an integer satisfying 0y3.

14. The method according to claim 13, wherein the coating composition comprises 10 parts by weight to 120 parts by weight of the binder, based on 100 parts by weight of the hollow silica particles.

15. The method according to claim 13, wherein the coating composition is prepared by adding the binder and the acid catalyst to the hollow silica particles, followed by stirring at 20 C. to 40 C. for 5 hours to 50 hours.

16. The method according to claim 13, wherein heat treatment is performed at a temperature of 50 C. to 200 C.

Description

EXAMPLE 1

(1) 1. Preparation of Siloxane Compound Binder

(2) 100 parts by weight of water, 433 parts by weight of isopropanol and 36 parts by weight of 0.1 M HNO.sub.3 were placed in a reactor, followed by stirring for 10 minutes. Next, 372 parts by weight of tetraethoxysilane (tetraethyl orthosilicate, TEOS) and 29 parts by weight of (3,3,3-trifluoropropyl)triethoxysilane were slowly introduced into the reactor through a funnel for 30 minutes. Next, the components were stirred at 50 C. for 2 hours, followed by cooling to room temperature, and then stirred again at a stirring speed of 200 rpm for 24 hours, thereby obtaining a transparent binder solution. It was confirmed that the solution had a solid content of 13 wt % and a pH of 2.2. The transparent solution was used in the preparation of a coating composition in the next stage without a separate purification process.

(3) 2. Preparation of Anti-Reflective Coating Composition

(4) 65 parts by weight of the prepared binder solution, 100 parts by weight of isopropanol and 65 parts by weight of a dispersion sol (Thrylya 4110, JGC C&C Co., Ltd., 20% w/w), which was prepared by dispersing hollow silica particles having a umber average diameter of 60 nm in isopropanol, were placed in a reactor, followed by stirring at room temperature for 24 hours, thereby preparing an anti-reflective coating composition. It was confirmed that the anti-reflective coating composition had a solid content of 10 wt % and a pH of 2.5.

(5) 3. Manufacture of Anti-Reflective Film

(6) The prepared anti-reflective coating composition was coated to a thickness of 100 nm onto a 20 m thick PET film using a Mayer bar, followed by drying at 130 C. for 2 minutes, thereby forming an coating layer. Next, the coating layer was subjected to aging in an oven at 60 C. for 24 hours, thereby manufacturing a final anti-reflective film.

EXAMPLE 2

(7) An anti-reflective coating composition and an anti-reflective film were prepared in the same manner as in Example 1 except that 100 parts by weight of water, 700 parts by weight of isopropanol, 50 parts by weight of 0.1 M HNO.sub.3, 350 parts by weight of tetraethoxysilane (tetraethyl orthosilicate, TEOS) and 100 parts by weight of (3,3,3-trifluoropropyl)triethoxysilane were used.

EXAMPLE 3

(8) An anti-reflective coating composition and an anti-reflective film were prepared in the same manner as in Example 1 except that 100 parts by weight of water, 700 parts by weight of isopropanol, 50 parts by weight of 0.1 M HNO.sub.3, 350 parts by weight of tetraethoxysilane (tetraethyl orthosilicate, TEOS) and 100 parts by weight of nonafluorohexyltriethoxysilane were used.

COMPARATIVE EXAMPLE

(9) An anti-reflective coating composition and an anti-reflective film were prepared in the same manner as in Example 1 except that a binder was prepared by condensation polymerization of only tetraethoxysilane without (3,3,3-trifluoropropyl)triethoxysilane.

EVALUATION

(10) 1. Molecular Weight of Binder

(11) A weight average molecular weight of each of the binders polymerized in Examples and Comparative Example was measured using an E2695 GPC apparatus (Water Co., Ltd.). Results are shown in Table 1.

(12) TABLE-US-00001 TABLE 1 Weight average molecular weight Example 1 12,000 Example 2 14,000 Example 3 18,000 Comparative Example 8,000

(13) 2. Index of Refraction

(14) An index of refraction of the coating layer of each of the prepared anti-reflective films was measured at wavelengths of 532 nm, 632.8 nm and 830 nm using a prism coupler, and an index of refraction at 550 nm was calculated using the Cauchy dispersion formula. Results are shown in Table 2.

(15) TABLE-US-00002 TABLE 2 Index of refraction Example 1 1.23 Example 2 1.23 Example 3 1.24 Comparative Example 1.26

(16) As shown in Table 2, it was confirmed that the coating layers of Examples could realize an index of refraction of 1.23 corresponding to a theoretically optimum value when the PET base was used.

(17) 3. Transmittance and Minimum Reflectance

(18) A transmittance of each of the manufactured anti-reflective films was measured using a CM-5 spectrophotometer (Konica Minolta Co., Ltd.). In addition, a back surface of each of the anti-reflective films was subjected to blackening treatment, followed by measurement of luminous reflectance and minimum reflectance. Results are shown in Table 3.

(19) TABLE-US-00003 TABLE 3 Transmittance Luminous Minimum (D65) reflectance (D65) reflectance (%) (%) (%) Example 1 96.2 0.7 0.6 Example 2 96.1 0.7 0.6 Example 3 96.0 0.9 0.7 Comparative 95.1 1.1 1.0 Example

(20) As shown in Table 3, it was confirmed that, since the anti-reflective films of Examples had a transmittance of 96% or more, a luminous reflectance from 0.7% to 0.8% and a minimum reflectance from 0.6% to 0.7%, the anti-reflective films of Examples exhibit excellent anti-reflection.

(21) Although the present invention has been described with reference to some embodiments, it should be understood that the embodiments are provided for illustration only, and that various modifications, changes, alterations, and equivalent embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be limited only by the accompanying claims and equivalents thereof.