KR101489860B1 - Preparatory method of tranparent film for antireflection effect - Google Patents

Abstract

The present invention relates to a process for producing an antireflective transparent film which imparts an antireflection effect to a substrate in a continuous roll-to-roll process. More particularly, the present invention relates to a process for producing an antireflective transparent film, , A silica sol consisting of 0.0001 to 0.1 mol of a surfactant, a lower alcohol having 1 to 5 carbon atoms, an acid having an acid concentration controlling acid and a residual water in a ratio of 0.0001 to 0.1 mol per mol of the silica precursor is coated on the heat resistant transparent film and baked at 80 to 150 캜 There is provided a transparent film having microcellular pores formed by the surfactant prepared by washing the surfactant with a detergent and drying the same, and imparting an antireflection effect to the substrate.

According to the present invention, it is possible to mass-produce a large-area antireflection film in a continuous process of a roll-to-roll system, thereby providing an antireflection film that is simple in process and low in manufacturing cost.

Anti-reflection, substrate, transmittance

Description

TECHNICAL FIELD The present invention relates to a transparent film for antireflection,

The present invention relates to an antireflection transparent film, and more particularly, to a method for producing an antireflection transparent film for imparting antireflection effect to a base material in a continuous roll-to-roll system.

It is common for a person to see the screen not see properly due to the reflections of sunlight on the TV when the sun is shining. Glasses and glasses used in displays are not 100% transmissive and have a reflectance of about 4.5%. For example, in the case of using glasses, the reflected light is caught by the reflection due to the reflection, which hinders the viewing of clear objects. In the case of the TV, the external light is reflected on the surface glass, which interferes with the viewing of the screen. In order to reduce such reflection of the transparent material, antireflection (AR) technology by multilayer coating is widely adopted. To prevent the glare caused by reflection and the invisible phenomenon of the screen, it is common to say that these techniques of lowering the reflectance of light in the visible region are referred to as AR coating technology. Experience. Glasses and glasses used in displays are not 100% transmissive and have a reflectance of about 4.5%. For example, in the case of using glasses, the reflected light is caught by the reflection due to the reflection, which hinders the viewing of clear objects. In the case of the TV, the external light is reflected on the surface glass, which interferes with the viewing of the screen.

In 1940, Geffken filed a 3-layer AR coating patent, and 4-layer AR coating technology has been in use for a long time. U.S. Patent No. 5856018 discloses a four layer coating technique of SiO2 / TiO2 / SiO2 / TiO2 applied over polymethylmethacrylate as described. 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. Thus, the conventional reflection reducing coating is composed of at least two to four layers of multilayer coating such as TiO 2 / SiO 2, SiO 2 / TiO 2 / SiO 2, TiO 2 / SiO 2 / TiO 2 / SiO 2, The process is complicated and it is not easy to apply to a large area. In particular, the TiO2 layer has a thickness of 15 nm to 30 nm and is applied as a very thin layer and is very sensitive to moisture, resulting in a large defect rate.

The present invention is to provide a method for producing a monolayer antireflection film capable of mass production using a roll-to-roll process.

An object of the present invention is to provide a product which is made of a single coating layer so that the coating process is simple and inexpensively realizes an antireflection effect.

Further, the present invention is to provide an antireflection film that can be easily applied to a large screen and can be economically produced.

According to the present invention, in a continuous process by a roll-to-roll process, an inorganic silica precursor or organic or inorganic hybrid silica precursor having three or more alkoxy groups on a heat-resistant transparent film, a cationic surfactant in a ratio of 0.0001 to 0.1 mol per 1 mol of the silica precursor, A silica sol composed of an anionic surfactant, a lower alcohol having 1 to 5 carbon atoms, a lower alcohol having an acid concentration controlling agent and water in a remaining amount is coated on the heat-resistant transparent film, baked at 80 to 150 캜, washed with a detergent, A transparent film having microcellular pores formed by the surfactant and imparting an antireflection effect to the substrate is provided. The coating process including the coating is generally performed by coating a silica sol with a dip coating (coating rate: 3 mm / s-100 mm / s), followed by baking with near infrared rays, followed by near-infrared drying. The entire production process can be mass-produced by coating and heat-cleaning in a single roll-to-roll process. Further, a transparent adhesive layer may be further added to the back surface of the heat-resistant transparent film to adhere to the substrate, whereby the antireflection effect can be imparted to the substrate. The adhesive layer may further include a release paper for protecting the adhesive layer. In addition, the transparent film for imparting an antireflection effect may further include a protective layer which is weakly bonded with a physical force, for example, a static electricity or a vacuum adsorption force, in order to protect the transparent film.

The silica precursor refers to a substance that forms a silica network structure by hydrogen substitution of an alkoxy group and subsequent dehydration reaction. The silica precursor is a tetraalkyl orthosilicate, an alkoxysilylalkane having at least four alkoxy groups, an alkoxysilylalkylene having three alkoxy groups, An alkoxyalkylsilane, an alkoxyalkenylsilane, an alkoxyarylsilane and an alkoxyaralkylsilane, or an organic or inorganic hybrid silica precursor. The alkyl is preferably C1 to C5 alkyl and the alkoxy group is preferably C1 to C5 substituted or unsubstituted alkoxy and most preferably C1 to C4 unsubstituted alkoxy, for example methoxy or < RTI ID = 0.0 > Ethoxy. The alkane or alkylene is preferably a C1 to C5 substituted or unsubstituted alkane or alkylene, preferably a C1 to C3 unsubstituted alkane or alkylene, for example ethane or ethylene, respectively. The silica precursor is most preferably tetramethylorthosilicate, TEOS (tetraethylorthosilicate), tetrapropylososilicate or tetrabutylososilicate.

The surfactants may be cationic surfactants such as DTAB (dodecyltrimethylammonium bromide), TTAB (tetradecyltrimethylammonium bromide), CTAB (cetyltrimethylammonium bromide), CTAC (cetyltrimethylammonium chloride), CDEAB (Sodium dodecylsulfonate), CAS (sodium alkylbenzenesulfonate), AS (sodium alkylsulfate ester), AES (sodium dodecylbenzenesulfonate), and the like are used as anionic surfactants. Alkyl ether sulfuric acid ester sodium), AOS (sodium alpha -olefin sulfonate), or SAS (sodium alkylsulfonate). These cationic and anionic surfactants are used in a ratio of 0.0001 to 0.1 mole per one mole of the silica precursor.

The lower alcohol having 1 to 5 carbon atoms is, for example, ethyl alcohol or propyl alcohol, preferably 10 to 80 molar ratio. The acid for controlling the acid concentration may be an inorganic acid or acetic acid, preferably hydrochloric acid. The amount of acid used to adjust the acid concentration is used in an amount of about 0.0001 to 0.1 mole ratio.

The heat-resistant transparent film used in the present invention is, for example, a polyester, a polycarbonate or a polyimide, and preferably a polyester (PET) film. Depending on the choice of silica precursor and transparent film, the baking temperature can be varied from 80 degrees to 150 degrees. The surfactant forms micelles in the sol component comprising the silica precursor and remains in the baking process, but exits the washing process and forms pores. The cleansing agents used in this washing process are water, lower alcohols having 1 to 5 carbon atoms, such as methyl alcohol, ethyl alcohol, propyl alcohol and / or butyl alcohol, and if necessary, oils, inorganic acids such as hydrochloric acid, acetic acid , Sulfuric acid, nitric acid, benzoic acid, carboxylic acid, phosphoric acid or chromic acid. Since the surfactant is well dissolved in the weakly acidic detergent, it can be cleaned without heating.

As the adhesive used for the back surface of the heat-resistant transparent film, for example, epoxy, acrylic, polyurethane or silicone adhesive is used as the transparent material. Such an adhesive is preferably thermosetting, including a crosslinkable component.

The silica sol antireflective coating of the present invention is not necessarily limited to this. However, the theoretical background is as follows. In the case of a single layer coating as shown in the following figure, the Fresnel`s equation equation ) Being

If the refractive index of the substrate is n ₁ = 1.23 when n _t = 1.52 and the thickness is 1/4 of the desired wavelength, the reflectance of 0% can be obtained as shown in the graph below.

To convert a material with a refractive index of 1.52 to a material with a refractive index of 1.23 (no material with a coating of 1.23 is found so far)

In the above formula

는 기공물질 계수

는 기공물질 밀도

The porosity coefficient

≪ / RTI >

는 비기공물질 계수

는 비기공물질 밀도

Lt; RTI ID = 0.0 >

Lt; RTI ID = 0.0 >

Therefore, if a material having a refractive index of 1.52 is present, a refractive index of 1.23 is obtained when the porosity is 60%. If the pore size is close to the wavelength of the light, the coating layer becomes opaque. Therefore, the pore size should be less than several hundred nanometers, which is much smaller than the wavelength of light (Mihai D. Morariu, University of Groningen, the Netherlands 9th July 2004) .

According to the present invention, it is possible to mass-produce a large-area antireflection film in a continuous process of a roll-to-roll system, thereby providing an antireflection film that is simple in process and low in manufacturing cost.

The following examples are provided to illustrate the present invention but are not to be construed as limiting the present invention.

In the examples of the present invention, solids coating, heat treatment, washing and drying processes were conducted by a continuous process using roll-to-roll equipment for the purpose of experiment on the mass production possibility of large-sized anti-reflective coating of single layer anti-

Example 1

Place the reaction vessel on a hot plate and set the temperature at 80 ° C. Add water, hydrochloric acid, and CTAB to ethanol for 1 hour, then add TEOS and react for 3 hours to make a sol. A sol of TEOS: EtOH: H ₂ O: HCl: CTAB molar ratio of 1: 55: 5: 0.004: 0.03 thus prepared was dip coated on PET film in a roll-to-roll manner at a speed range of 6.3 to 6.5 mm / Were also heat-treated in the near-infrared. Subsequently, it was washed with a detergent (750 ml of ethanol + 10.5 g of hydrochloric acid) and dried at 100 ° C near infrared. The reflectance and the transmittance in the case of not washing and in the case of washing were measured and shown in Figs. 1A and 1B, respectively. The average reflectance and the average transmittance are shown in Table 1. A surface TEM image of the dried PET film was taken and shown in FIG.

Examples 2 to 6

The results are shown in Table 1. The results are shown in Tables 1 and 2. The reflectance graph and the transmittance graph are shown in FIGS. 2A to 6B. In Table 1, the component ratio is a molar ratio based on 1 mole of TEOS. The average reflectance and the average transmittance are shown in Table 1.

Table 1

Examples 7 to 11

The same procedure as in Example 1 was carried out except that the surfactant was changed as shown in Table 2 or a plurality of surfactants were used in different conditions. The reflectance graph and the transmittance graph after cleaning are shown in FIG. In the following Table 2, the component ratio is a molar ratio based on 1 mole of TEOS.

Examples 12 to 16

The same procedure as in Example 1 was carried out except that the surfactant was changed as shown in Table 2 or a plurality of surfactants were used in different conditions. The reflectance graph and the transmittance graph after cleaning are shown in Fig.

                                      Table 2

1A and 1B are graphs of reflectance and transmittance of the visible light region of Example 1, respectively

2A and 2B are graphs of reflectance and transmittance of the visible light region of Example 2

3A and 3B are graphs of reflectance and transmittance of the visible light region of Example 3, respectively

FIGS. 4A and 4B are graphs of reflectance and transmittance of the visible region of Example 4, respectively

5A and 5B are graphs of reflectance and transmittance in the visible region of Example 5

6A and 6B are graphs of reflectance versus transmittance of the visible light region of Example 6

7 is a TEM TEM image of the surface of the antireflection film produced in Example 1. Fig.

Claims (8)

An inorganic silica precursor having three or more alkoxy groups or an organic or inorganic hybrid silica precursor, a surfactant in a ratio of 0.0001 to 0.1 mole per 1 mole of the silica precursor, a lower alcohol having 1 to 5 carbon atoms, , The coated transparent film is baked at 80 to 150 캜, the remaining surfactant of the baked transparent film is washed with a cleaning agent, and the washed transparent film is dried A method for producing an antireflection transparent film which gives an antireflection effect to a base material in a roll-to-roll process The method for producing an antireflective transparent film according to claim 1, wherein the cleaning agent is water or a lower alcohol having 1 to 5 carbon atoms A process for producing an antireflective transparent film for imparting antireflection effect to a substrate, wherein the cleaning agent further comprises hydrochloric acid, acetic acid, sulfuric acid, nitric acid, benzoic acid, carboxylic acid, phosphoric acid or chromic acid The method for producing an antireflection transparent film according to claim 1, wherein the silica sol is coated on the heat-resistant transparent film, followed by baking and drying to produce an antireflection transparent film giving an antireflection effect to a substrate formed by infrared irradiation The antireflection film as claimed in any one of claims 1 to 4, wherein the silica precursor is tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate or tetrabutyl orthosilicate, ≪ / RTI > The method for producing an antireflective transparent film according to any one of claims 1 to 4, wherein the transparent film is a polyester film, 5. The composition of any one of claims 1 to 4 wherein the surfactant is selected from the group consisting of DTAB (dodecyltrimethylammonium bromide), TTAB (tetradecyltrimethylammonium bromide), CTAB (cetyltrimethylammonium bromide), CTAC (cetyltrimethylammonium chloride ), Sodium alkylsulfonate (sodium alkylsulfonate), sodium alkylsulfonate (sodium alkylsulfonate), sodium alkylsulfonate (sodium alkylsulfonate), sodium alkylsulfonate (sodium alkylsulfonate), sodium alkylbenzenesulfonate ), A method for producing an antireflection transparent film which gives an antireflection effect to a substrate which is a plurality of surfactants selected from the group consisting of AOS (sodium alpha-olefin sulfonate) and SAS (sodium alkylsulfonate) delete

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