Method for preparing a barrier film

Abstract

The present application relates to a method for preparing a barrier film. The present application can provide a method for preparing a barrier film having excellent barrier characteristics and optical performances. The barrier film produced by the method of the present application can be effectively used not only for packaging materials of as foods or medicines, and the like, but also for various applications, such as members for FPDs (flat panel displays) such as LCDs (Liquid Crystal Displays) or solar cells, substrates for electronic papers or OLEDs (Organic Light Emitting Diodes), or sealing films.

Claims

1. A method for preparing a water vapor transmission barrier film, the method comprising: coating a composition comprising an amine catalyst and a polysilazane on a base layer via a wet coating process to form a barrier layer, wherein: the amine catalyst is ammonia, ammonium hydroxide, ammonium chloride, trialkylamine, dialkylamine, monoalkyl amine, dialkanolamine, dialkylalkanolamine, trialkanolamine or dialkylaminoalkyl trialkoxysilane; and the amine catalyst is present in an amount within a range of 0.1 to 10 parts by weight relative to 100 parts by weight of the polysilazane; and subjecting the barrier layer to a curing process that includes performing a plasma hardening treatment comprising plasma-treating a surface of the barrier layer containing the polysilazane and the amine catalyst in a processing space in which water vapor, a discharge gas, and oxygen as a reaction gas are injected resulting in maintaining a vapor pressure of water vapor in the processing space at about 5% or more to cause oxidation of the polysilazane whereby SiN units of the polysilazane are converted into SiO units in a thickness direction to layer satisfy Equation 2 below thereby yielding the water vapor transmission barrier film:
0.75d/(c+d)0.97[Equation 2] wherein: c is the number of SiN units present in the barrier layer after the plasma hardening treatment, and d is the number of SiO units present in the barrier layer after the plasma hardening treatment.

2. The method according to claim 1, wherein the polysilazane has a repeating unit of Formula 1: ##STR00002## wherein each of R.sup.1, R.sup.2 and R.sup.3 separately is hydrogen, an alkyl group, an alkenyl group, an aryl group, a carbonyl group, a hydroxyl group or an alkoxy group.

3. The method according to claim 2, wherein R.sup.1 to R.sup.3 in the repeating unit of the Formula 1 are hydrogen atoms.

4. The method according to claim 1, wherein the polysilazane is present in an amount of 55 wt % or more.

5. The method according to claim 1, wherein the plasma-treating is carried out while maintaining a hydrogen partial pressure in the processing space at 2.0010.sup.5 Pa or more.

6. The method according to claim 1, wherein a ratio (H/A) of an injection volumetric flow rate (H) of the water vapor to an injection volumetric flow rate (A) of the discharge gas is maintained at 0.4 or more.

7. The method according to claim 1, wherein a ratio (H/O) of an injection volumetric flow rate (H) of the water vapor to an injection volumetric flow rate (O) of the oxygen is maintained at 0.4 or more.

8. The method according to claim 1, wherein a process pressure during the plasma-treating is maintained at 50 mTorr or more.

9. The method according to claim 1, wherein a power density during the plasma-treating is maintained at 0.2 W/cm.sup.2 or more.

10. The method according to claim 1, wherein a process energy density during the plasma-treating is maintained at 2 J/cm.sup.2 or more.

11. The method according to claim 1, wherein the water vapor transmission barrier film further comprises an undercoating layer between the base layer and the barrier layer.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 to 3 show the structure of a barrier film according to one embodiment of the present application.

(2) FIGS. 4 and 5 show element content changes in the thickness direction of the barrier layers of Example 3 and Comparative Example 2, respectively.

EXPLANATION OF REFERENCE NUMERALS

(3) 1000: barrier film 100: base layer 200: undercoating layer 300: barrier layer 400: protective coating layer 500: anti-blocking layer

MODE FOR INVENTION

(4) Hereinafter, the preparation method of the present application will be described through Examples and Comparative Examples according to the present application, but the scope of the present application is not limited by the following examples.

Example 1. Preparation of Barrier Film (A1)

(5) A barrier film having a structure as shown in FIG. 1 was prepared by the following method. An undercoating layer (intermediate layer) having a thickness of 900 nm was formed on a PET (poly(ethylene terephthalate)) having a thickness of 50 m using an acrylate composition comprising 40 parts by weight of silica nanoparticles having a size of 10 to 15 nm (tris(2-hydroxyethyl)isocyanurate triacrylate (SR368):dipentaerythritol hexaacrylate (DPHA):pentaerythritol triacrylate (PETA)=2:1:7). Subsequently, a polysilazane composition prepared by adding 1 part by weight of dimethylethanolamine (DMEA) to a polysilazane solution (solvent: dibutyl ether) containing about 4 wt % of perhydropolysilazane, relative to 100 parts by weight of the solid content of perhydropolysilazane was coated on the undercoating layer using a Meyer bar, and maintained at 70 C. for 1 minute and at 130 C. for 2 minutes and dried to form a barrier layer having a thickness of about 165 nm.

(6) The barrier layer was treated with a plasma discharge device using a Ti electrode and cured. At this time, argon gas was injected as a discharge gas through a water bubbler so that the ratio of the injection flow rates of discharge gas (Ar gas):reaction gas (O2):water vapor was 3:4:3 or so (discharge gas injection flow rate: 75 sccm, reaction gas injection flow rate: 100 sccm, and steam injection flow rate: 75 sccm). At this time, the process pressure was 250 mTorr, the temperature was 110 C., the applied power of the plasma treatment was 1094 W, and the process energy was about 20 J/cm.sup.2. The plasma treatment time was about 3 minutes to 5 minutes or so.

Example 2Preparation of Barrier Film (A2)

(7) A barrier film was prepared in the same manner as in Example 1, except that the barrier layer was formed using a composition prepared by adding 2 parts by weight of dimethylethanolamine (DMEA) relative to 100 parts by weight of the solid content of perhydropolysilazane.

Example 3Preparation of Barrier Film (A3)

(8) A barrier film was prepared in the same manner as in Example 1, except that the barrier layer was formed using a composition prepared by adding 3 parts by weight of dimethylethanolamine (DMEA) relative to 100 parts by weight of the solid content of perhydropolysilazane.

Example 4Preparation of Barrier Film (A4)

(9) A barrier film was prepared in the same manner as in Example 1, except that the barrier layer was formed using a composition prepared by adding 1 part by weight of triethanolamine (TEA) instead of dimethylethanolamine (DMEA) relative to 100 parts by weight of the solid content of perhydropolysilazane.

Example 5Preparation of Barrier Film (A5)

(10) A barrier film was prepared in the same manner as in Example 1, except that the barrier layer was formed using a composition prepared by adding 2 parts by weight of triethanolamine (TEA) instead of dimethylethanolamine (DMEA) relative to 100 parts by weight of the solid content of perhydropolysilazane.

Example 6Preparation of Barrier Film (A6)

(11) A barrier film was prepared in the same manner as in Example 1, except that the barrier layer was formed using a composition prepared by adding 3 parts by weight of triethanolamine (TEA) instead of dimethylethanolamine (DMEA) relative to 100 parts by weight of the solid content of perhydropolysilazane.

Example 7Preparation of Barrier Film (A7)

(12) A barrier film was prepared in the same manner as in Example 1, except that the barrier layer was formed using a composition prepared by adding 3 parts by weight of diethylaminopropyltrimethoxysilane (DEAPTMS) relative to 100 parts by weight of the solid content of perhydropolysilazane.

Comparative Example 1Preparation of Barrier Film (B1)

(13) A barrier film was prepared in the same manner as in Example 1, except that no water vapor was injected upon the plasma treatment.

Comparative Example 2Preparation of Barrier Film (B2)

(14) A barrier film was prepared in the same manner as in Example 1, except that the amine catalyst (DMEA) was not added.

Experimental Example 1Measurement of Water Vapor Transmission Rate of Barrier Film

(15) The water vapor transmission rates (WVTR, unit: mg/m.sup.2/day) of the barrier films prepared according to Examples and Comparative Examples were evaluated by AQUATRAN 1 (Mocon) at 30 C. and 100% relative humidity and shown in Table 1 below.

(16) TABLE-US-00001 TABLE 1 Comparative Example Example 1 2 3 4 5 6 7 1 2 WVTR 0.74 <0.5 <0.5 <0.5 <0.5 0.90 0.85 2.6 2.0

Experimental Example 2

(17) The contents of elements in the thickness direction of the barrier layer in the barrier films of Example 3 and Comparative Example 2 were analyzed by the EDS line profile. The JEOL JEM-ARM200F Field Emission Transmission Electron Microscope equipped with Schottky Field emitter, STEM Cs corrector and Energy Dispersive X-Ray Spectrometer was used as the analyzer and analyzed at an accelerating voltage of 200 kV and resolution capability point resolution (0.19 mm) and line resolution (0.10 nm), where the conversion ratio of SiN bond units to SiO bond units was calculated in the region corresponding to in the thickness direction of the barrier layer from the side of the barrier layer contacting the undercoating layer according to the following general formula.

(18) FIGS. 4 and 5 are the analysis results of the EDS line profile for Example 3 and Comparative Example 2, respectively. As a result of calculation, the corresponding value in Example 3 was 0.97, and the corresponding value in Comparative Example 2 was about 0.74. Through these results, it can be confirmed that the method of the present application can exhibit excellent barrier characteristics, since the conversion of polysilazane to SiO is more effectively achieved.
b/(a+b)[General Formula 1]

(19) In General Formula 1, a means the number of SiN bond units existing in a region corresponding to of the thickness of the barrier layer based on the side where the barrier layer contacts the undercoating layer, and b means the number of SiO bond units existing in a region corresponding to of the thickness of the barrier layer based on the side where the barrier layer contacts the undercoating layer.