KR101772400B1

KR101772400B1 - Barrier Film

Info

Publication number: KR101772400B1
Application number: KR1020150128918A
Authority: KR
Inventors: 구은회; 김선민
Original assignee: 한국세라믹기술원
Priority date: 2015-09-11
Filing date: 2015-09-11
Publication date: 2017-08-29
Also published as: KR20170031419A

Abstract

In the present invention, in a barrier film for display comprising a base film and a moisture barrier layer, a planarization primer coating layer formed of a UV-blocking composition in which UV-blocking particles are dispersed in a binder resin is added between the base film and the moisture barrier layer Wherein the moisture barrier barrier film comprises a water barrier film. The barrier film of the present invention is formed by depositing a metal, a metal or a non-metal oxide having a large thermal expansion coefficient on a base film after forming a UV-blocking layer. Therefore, the residual stress applied to the barrier film during the manufacturing process and the manufacture of the module is small, and the film has UV-blocking property. Accordingly, moisture barrier property can be maintained even for a long time continuous repetitive deformation.

Description

{Barrier Film}

More particularly, the present invention relates to a moisture barrier film which is excellent in moisture barrier effect by laminating a thin film formed by using a metal compound having a large thermal expansion coefficient on a plastic base film, Barrier film, which is excellent in UV-blocking property while maintaining transparency to visible light by interposing a primer coating layer containing UV-blocking particles, and is capable of maintaining moisture and UV-blocking property even in successive repeated deformation.

With the recent rise in crude oil prices, interest in the use of renewable energy is increasing. Solar energy is one of the infinite and most likely resources among the various alternatives of renewable energy. Recently, research on solar cells is underway, but it is necessary to develop solar cells with lower cost and higher efficiency.

Research and development of organic solar cells using organic materials in solar cells is underway, and organic solar cells having energy conversion efficiency of about 12% are reported recently. However, since organic materials are vulnerable to light and moisture, barrier technology (moisture and UV blocking technology or encapsulation technology) is one of the important technologies in the production of organic solar cells for commercialization. That is, the organic solar cell is very sensitive to moisture and light, so that the allowable value of water vapor transmission rate (WVTR) is 10 ^-6 g / m 2day (the amount of water permeated per one square meter of substrate per day). Also, when exposed to light, the characteristics are reduced by up to 30% depending on the thickness of the light absorption layer due to the staebler-wronski effect. Since organic solar cells use glass substrates, there is no problem of water permeability and UV-blocking property of the substrate itself, and the barrier properties of packaging materials and sealing materials are improved to solve moisture permeation and UV-blocking problems.

On the other hand, flexible electronic products having a flexible shape are expected to occupy an important position in the market in the future because they are light, bent, and folded. In particular, if flexible organic solar cells are manufactured, they can be applied to wearable devices, which are becoming a recent issue. However, this type of flexible electronic device causes a big problem because it uses plastic (polymer) as substrate instead of glass. In other words, since the plastic substrate has a structure having a low density of intermolecular densities, a large amount of moisture enters the device through the substrate itself. In addition, there is little research on plastic substrates that block the UV region that affects the lifetime of organic solar cells. Therefore, techniques for preventing WVTR and blocking the UV region have been developed by putting various types of barrier films on a plastic substrate. To this end, the undercoat layer produced upon the addition of IZO, or by depositing an IZO to form a layer to block the UV region has a composition having a multilayer film structure produced by the ceramic gas barrier layer deposited on a polymer film, such as SiOx or AlO _y representative ( Patent Document 1).

On the other hand, in order to produce a film having excellent moisture barrier properties with a UV-blocking layer of about 99% or more and a visible ray transmittance of 90% or more, the difference in thermal expansion coefficient between the plastic substrate and the gas barrier ceramic layer is reduced, And the UV cut-off is maximized. In addition, in the thin film manufacturing process, the process temperature should be set as low as possible to minimize the residual stress caused by the thermal history. As a result of efforts made by the inventors, the inventors of the present invention have confirmed that the barrier film using the UV-blocking layer through IZO is excellent in not only water barrier property but also UV-blocking and visible light transmittance.

Korean Patent Laid-Open Publication No. 2013-0046681

It is an object of the present invention to provide a moisture barrier film which is excellent in UV-blocking property and can maintain moisture and UV-blocking property even in successive repeated deformation.

The moisture barrier film according to the present invention is a barrier film for a display comprising a base film and a moisture barrier layer, wherein a barrier film formed between the base film and the moisture barrier layer is formed of a UV- And a planarization primer coating layer.

Wherein the UV-blocking composition comprises, based on 100 parts by weight of the binder resin; 1 to 20 parts by weight of at least one UV-blocking particle selected from the group consisting of CeO ₂ , TiO ₂ , ZnO and IZO.

The average particle diameter of the UV-blocking particles is preferably 10 to 100 nm.

The coefficient of linear thermal expansion of the moisture barrier layer is preferably in the range of 5.7 to 6.3 x 10 ^-6 캜 ^-1 .

Wherein the moisture barrier layer comprises at least one oxide of a metal or a non-metal selected from the group consisting of niobium (Nb), terbium (Tb), magnesium (Mg), aluminum (Al), silica (Si) Or a nitride layer formed from a nitride oxide.

The thickness of the primer coating layer is 0.1 to 5 占 퐉; The thickness of the thin film layer is preferably 50 to 200 nm.

In the moisture barrier film according to the present invention, a protective layer may be formed on the moisture barrier layer to have a structure in which a base film, a UV-blocking planarizing primer coating layer, a moisture barrier layer and a protective layer are laminated in order.

Between the base film and the protective layer, two or more repeating units composed of a primer coating layer and a moisture barrier layer may be provided.

The barrier film of the present invention is formed by depositing a metal, a metal or a non-metal oxide having a large thermal expansion coefficient on a base film after forming a UV-blocking layer. Therefore, the residual stress applied to the barrier film during the manufacturing process and the manufacture of the module is small, and the film has UV-blocking property. Accordingly, moisture barrier property can be maintained even for a long time continuous repetitive deformation.

1 is a schematic cross-sectional view of a first embodiment of a barrier film according to the present invention,
2 is a schematic cross-sectional view of the second embodiment,
3 is a schematic cross-sectional view of the third embodiment,
4 is a schematic diagram schematically illustrating a configuration of an apparatus for measuring moisture permeability of a barrier film of the present invention.

The moisture barrier film according to the present invention is a barrier film for a display comprising a base film and a moisture barrier layer, wherein a barrier layer is provided between the base film and the moisture barrier layer and a UV- And further comprising a formed flattening primer coating layer.

[Structure of barrier film]

Hereinafter, a barrier film according to the present invention will be described with reference to the drawings.

Figures 1 to 3 are schematic diagrams of embodiments of a barrier film according to the present invention. In the drawings, the thickness of each layer or the ratio thereof is illustrative, and in actuality, the thickness ratio of each layer may be different from that exemplified.

The barrier film 10 according to the first embodiment of the present invention according to the first embodiment of the present invention is a barrier film 10 interposed between the base film 11 and the water barrier layer 13 with a UV-blocking planarizing primer coating layer 12 interposed therebetween.

The barrier film 20 according to the second embodiment of FIG. 2 is obtained by sequentially laminating the base film 21, the planarizing UV-blocking primer coating layer 22 and the moisture barrier layer 23, And a protective layer 24 is further formed thereon.

The barrier film 30 according to the third embodiment in Fig. 3 has a first UV-blocking primer coating layer 32, a first moisture barrier layer 33, and a second UV-blocking primer coating layer 33 between the base film 31 and the protective layer 34. [ A UV-blocking primer coating layer 32 'and a second moisture barrier layer 33', and at least two moisture barrier layers are formed in one barrier film. Although not shown, in another embodiment of the barrier film according to the present invention, the moisture barrier layer can be provided in three or more layers.

[Base film]

The base film serves as a support for a barrier film composed of a plurality of layers. As the base film, any plastic film having heat resistance and flexibility as well as light transmittance can be used without limitation. The light transmittance required for use as the base film should be not less than 85%, preferably not less than 90%, in the visible light region.

The material of the plastic film that can be used for the base film includes, for example, polyolefin resin such as polyethylene resin and polypropylene resin, polyester such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, diacetyl cellulose, Cellulose resins such as acetyl cellulose and acetyl cellulose butyrate, and at least one polymer selected from polyether sulfone, polycarbonate, polyimide, polyarylate, and epoxy resins. Particularly, a film formed of polyethylene terephthalate or the like is preferable because of its high strength and low cost.

In order to increase the mechanical properties and the thermal and optical properties of the plastic film, at least one selected from a filler or a fiber-type filler and a mixture thereof may be further added to the polymer. Examples of the filler include IZO, ZnO, metal, glass powder, diamond powder, silicon oxide, clay, calcium phosphate, magnesium phosphate, barium sulfate, aluminum fluoride, calcium silicate, magnesium silicate, barium silicate, barium carbonate, Barium hydroxide, and aluminum silicate may be used. As the filler of fiber type, glass fiber or woven glass fiber may be used.

On the other hand, the base film may be subjected to a surface treatment using ultraviolet ray, corona, flame, plasma, sputtering, ion beam, chemical, or the like in advance in order to improve adhesion with a water barrier layer or a UV-blocking primer coating layer described later. The thickness of the base film can be appropriately adjusted according to each material in consideration of flexibility and light transmittance. For example, when the base film is formed of a polyester-based polymer such as polyethylene terephthalate or polyethylene naphthalate, a film having a thickness of 20 to 200 탆 may be used.

[Water barrier layer]

The barrier film of the present invention comprises a moisture barrier layer laminated on a base film with a UV-blocking layer interposed therebetween.

Wherein the moisture barrier layer comprises at least one oxide of a metal or a non-metal selected from the group consisting of niobium (Nb), terbium (Tb), magnesium (Mg), aluminum (Al), silica (Si) Or a nitride oxide. When the metal or nonmetal compound is formed as a thin film, the Coefficients of Linear Thermal Expansion measured at 20 ° C has a value in the range of 5.7 to 6.3 x 10 ^-6 ° C ^-1 . The coefficient of linear expansion of the metal or non-metal compound is smaller than the coefficient of linear expansion of alumina (Al ₂ O ₃ ) of 7.4 × 10 ^-6 ° C. ^-1 . Accordingly, there is an advantage in that residual stress remaining on the barrier film during the production process of a film or a module is reduced because there is little difference between the metal oxide thin film layer and a base material film made of a plastic material having a larger linear expansion coefficient value. As a result of such reduction of the residual stress, the barrier film of the present invention according to the present invention not only has few defects such as cracks in the thin film generated during processing but also occurs due to continuous repeated deformation after completion of the module including the barrier film Is reduced. Therefore, the moisture permeability of the barrier film can be remarkably reduced.

The moisture barrier layer may be formed directly on the base film or formed on the UV-blocking primer coating layer. As a method of forming a thin film of a metal or a nonmetal compound on the base film or the UV-blocking primer coating layer, a method known in the art can be employed. For example, the moisture barrier layer may be formed as a thin film by chemical vapor deposition (CVD), sputtering, evaporation, atomic layer deposition, or ion plating.

The thickness of the moisture barrier layer is preferably 20 to 500 nm, more preferably 30 to 300 nm, and still more preferably 50 to 200 nm. If the thickness of the moisture barrier layer is less than 20 nm, it may be difficult to obtain a desired level of moisture barrier performance because it is difficult to obtain continuity of the moisture barrier layer. On the other hand, if it is more than 500 nm, the flexibility of the layer is lowered and the residual stress is increased inside, so that the possibility of occurrence of bond such as cracks of the layer is increased and it is difficult to maintain moisture barrier property by continuous repeated deformation.

On the other hand, in the embodiment of the barrier film according to the present invention, the moisture barrier layer may be formed as a single layer (first to third embodiments) or may have a multilayer structure. When the moisture barrier layer is composed of a plurality of layers, each of the moisture barrier layers may be formed of the same metal compound composition or may have a different composition, and the thickness of each layer may be arbitrarily adjusted within a range of the total thickness of 20 to 500 nm . A UV-blocking primer coating layer may be interposed between the plurality of moisture barrier layers as in the fourth embodiment illustrated in FIG.

[UV cut planarization primer coating layer]

The UV-cut planarization primer coating layer may be formed between the two layers to enhance the interlayer adhesion of the substrate layer and the moisture barrier layer and to block light in the UV-region. In addition, the UV-cut planarization primer coating layer may serve to smooth the surface on which the moisture barrier layer is laminated and to relieve the stress experienced by the barrier film when mechanical deformation occurs after bonding. It improves the light stability by blocking the light of the UV-region which lowers the lifetime of the organic solar cell.

The intended UV-cut planarization primer coating layer is composed of a binder resin and IZO, and an additive added as required. As the binder resin constituting the adhesive layer, a thermosetting resin or an ionizing radiation-curable resin which is crosslinked and cured by heating and / or ionizing radiation is suitably used. These resins are crosslinked and cured to improve the adhesion between the base film and the metal compound thin film.

The thermosetting resin is a thermosetting resin which is obtained by applying a coating liquid containing a thermosetting resin onto a plastic film and then crosslinking and curing the thermosetting resin by heat so that a thermosetting resin capable of crosslinking and curing by heat below the heat- desirable. Concretely, crosslinking and curing of a crosslinkable resin such as melamine, epoxy, epoxy silane, aminoalkyd, urethane, acrylic, polyester, phenol and the like can be used.

These can be used alone, but it is preferable to add a curing agent in order to further improve the hardness of the crosslinkable and crosslinked hard coat film. In addition, in the present invention, the thermosetting resin also includes a room temperature curing type resin which is cured at room temperature (5 to 35 DEG C).

As the curing agent, compounds such as polyisocyanate, amino resin, epoxy resin, and carboxylic acid can be appropriately used in accordance with a suitable resin.

As the ionizing radiation curable resin, it is preferable to use a material formed from a coating material that can be crosslinked and cured by irradiation with at least ionizing radiation (ultraviolet ray or electron beam). As such an ionizing radiation curing coating material, there can be used one or a mixture of two or more kinds of photocationic polymerizable photopolymerizable resin, photo radical polymerizable photopolymerizable prepolymer or photopolymerizable monomer, and the like. Various additives may be added to such ionizing radiation curable paints, but in the case of using ultraviolet rays during curing, it is preferable to add a photopolymerization initiator, an ultraviolet sensitizer, and the like.

On the other hand, as the UV-blocking particles included in the UV-blocking composition, for example, one or more particles selected from the group consisting of CeO ₂ , TiO ₂ , ZnO and IZO can be used. According to the repeated experiments of the inventors, it has been confirmed that when the above-mentioned particles are added to a composition for forming a primer coating layer, UV-light can be blocked with a transmittance of 10% or less, preferably 1% or less with respect to a UV-wavelength of 300 nm or less .

The size of the UV-blocking particles is preferably 100 nm or less. In order to improve the transmittance of visible light, it should be about 100 nm or less which is 1/4 of 400 nm which is a short wavelength of visible light. If the thickness exceeds 100 nm, the transmittance of the visible light region decreases due to the size of the particles.

On the other hand, the content of the UV-blocking particles in the composition is 1 to 20 parts by weight, preferably 5 to 15 parts by weight, more preferably 9 to 13 parts by weight, based on 100 parts by weight of the binder resin. If the amount is less than 1 part by weight, the UV shielding property is deteriorated. If the amount is more than 20 parts by weight, the roughness of the flattening layer becomes large and water permeability increases.

The UV-cut planarization primer coating layer may contain a thermoplastic resin such as an acrylic adhesive resin in addition to the above-mentioned curable resin. Additives such as a leveling agent, an ultraviolet absorber, an antioxidant, an antistatic agent, a pigment, and a dye may be added in addition to the resin in a range that does not impair the original function of moisture and UV blocking and interlayer adhesion. UV reduces the characteristics of organic solar cells to about 30%. Therefore, by using materials that block UV, the optical stability of photovoltaic cells, the lifetime of solar cells, and the optical spacer function as optical spacers .

The adhesive layer may be provided with a separate function by adding an additive. For example, a water absorbent may be further contained in the primer coating layer.

The planarizing primer coating layer is formed by drying and curing the above-mentioned thermosetting resin or ionizing radiation curing coating material by heating and / or ionizing radiation.

The thickness of the planarizing primer coating layer is preferably 0.1 to 5 占 퐉, more preferably 0.3 to 3 占 퐉. When the coating thickness is thinner than 0.1 탆, the transparency is good but the adhesive force is poor. When it is thicker than 5 탆, the adhesive property is excellent, but the uniformity of the film thickness is poor, and uniformity of the thin film formed by vapor deposition, sputtering, The continuity is degraded.

[Protective layer]

On the other hand, the protective layer functions to protect the moisture barrier layer, which is produced in the form of a thin film of a metal compound, from external physical impact such as scratches generated during handling.

The polymer composition constituting the protective layer in the barrier film according to the present invention and the forming method thereof are qualitatively similar to those of the primer coating layer. However, it is possible to form the protective layer by adjusting the surface hardness of the layer formed by various methods such as changing the specific composition to 2H or more, more preferably 3H or more, based on the pencil hardness.

For example, as one method of controlling the hardness, there may be mentioned a method of mixing the monomer or oligomer constituting the resin used in the protective layer or adjusting the addition of the resin or additive to be added. This method may be particularly effective in the case of using an acrylate-based monomer having a hydroxy group or an amino group as a photopolymerizable monomer.

Another method for controlling the surface hardness of the protective layer may be, for example, a method of controlling the irradiation amount of the ionizing radiation in the case of the ionizing radiation curing resin. In addition, various known methods can be applied.

The thickness of the protective film is not particularly limited, but is preferably 0.1 to 5 占 퐉.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

&Lt; Example 1 >

A barrier film composed of a " base film / UV blocking planarizing primer coating layer / water barrier layer " having the layer structure of FIG. 1 was prepared by the following steps.

As a first step, IZO for UV-blocking was added to an organic hybrid epoxy polymer solution on a primer-treated PET film ( SKC product ) having a thickness of 100 μm, and the coating solution was applied by a spin coating method, To form a 1 占 퐉 planarization UV-blocking primer coating layer.

As a second step, SiO ₂ was deposited on the UV-blocking primer coating layer to form a moisture barrier layer. Sputtering for deposition was carried out by flowing 500 W of power and 30 sccm of Ar gas. A moisture barrier layer with a thickness of 100 nm was deposited at a deposition rate of 20 A / min at a process pressure of 2x10 < ^-3 > Torr.

&Lt; Example 2 >

After the second step in Example 1, Al ₂ O ₃ was laminated to prepare a barrier film composed of `base film / UV-cut planarizing primer coating layer / water barrier layer 1 / water barrier layer 2 '. In Example 2, the thickness of each of the moisture barrier layers formed was 100 nm. Al ₂ O ₃ was deposited by sputtering at a deposition rate of 16 Å / min at a power of 500 W and a process pressure of 2 × 10 ^-3 Torr to a thickness of 100 nm.

&Lt; Example 3 >

After the third step of Example 2, the moisture barrier layer 1 (SiO ₂ ) / moisture barrier layer 2 (Al ₂ O ₃ ) was laminated to form a base film / UV-blocking planarizing primer coating layer / water layer Barrier layer 1 / water barrier layer 2 / water barrier layer 1 / water barrier layer 2 '. The thickness of each of the moisture barrier layers formed in Example 3 was 100 nm.

&Lt; Comparative Example 1 &

In the second step of Example 2, a barrier film was prepared in the same manner as in Example 2 except that a planarizing primer coating layer without addition of IZO was used in forming the UV-cut planarization primer coating layer.

&Lt; Comparative Example 2 &

In the second step of Example 3, a barrier film was prepared in the same manner as in Example 3 except that a planarizing primer coating layer without addition of IZO was used in forming the UV-cut planarization primer coating layer.

Optical characteristics and water permeability of the barrier film were measured.

Optical properties were measured by UV-visible spectrophotometer, a s-3100 model from scinco, and the transmittance was measured for UV-wavelengths from 320 to 380 nm.

On the other hand, the moisture permeability was measured using a self-produced moisture permeability meter, and the moisture permeability of the self-produced water permeability is shown in FIG. The moisture permeability of the barrier film is lower than that of the bottom chamber which maintains a high partial pressure of water below the film when maintaining a constant partial pressure difference of water between the upper chamber and the lower chamber of the film. Is defined as the amount of water permeating per unit area per hour and was measured from the results of monitoring the pressure over time through the measuring instrument of FIG.

The water permeability was measured by measuring the pressure before and after water permeation under the conditions of relative humidity of 100% and temperature of 38 ° C. The moisture permeability and optical characteristics of the barrier film thus produced are shown in Table 1.

The above results are summarized in Table 1 below.

The moisture barrier layer
material Optical characteristic Water permeability
(g / m 2 · day)
T (%), 550 nm T (%) UV Example 1 SiO2 89 One 0.0001 Example 2 Al2O3 88 One 0.0003 Example 3 SiO2 / Al2O3 88 One 0.000007 Comparative Example 1 SiO2 89 95 0.001 Comparative Example 2 Al ₂ O ₃ 89 95 0.002

In the above Table 1, the barrier film according to the present invention having a thin film formed using the UV-cut planarizing layer, cut off 99% of the UV wavelength light that affects the lifetime of the solar cell.

Therefore, the UV barrier film of the present invention can be used as a protective film for an organic solar cell, which is liable to be deteriorated by moisture and a reduction in lifetime caused by light with a UV wavelength. In addition, it can be used as a protective film for display devices such as LCD and OLED.

10, 20, 30. Barrier film
11, 21, 31. Base film
12, 22, 32, 32 '.. UV cut planarization primer coating layer
13, 23, 33, 33 '. The moisture barrier layer
24, 34. The protective layer

Claims

A barrier film for display comprising a base film and a moisture barrier layer,
Further comprising a planarizing primer coating layer formed between the base film and the moisture barrier layer and formed of a UV-blocking composition in which UV-blocking particles are dispersed in a binder resin,
Wherein the UV-blocking composition comprises, based on 100 parts by weight of the binder resin; At least one UV-blocking particle selected from the group consisting of CeO2, TiO2, ZnO and IZO (Indium Zinc Oxide) 1 to 20 parts by weight,
Wherein the binder resin is a thermosetting resin or an ionizing radiation curable resin, the UV-blocking particles have an average particle diameter of 100 nm or less,
Wherein the moisture barrier layer has a Coefficients of Linear Thermal Expansion in the range of 5.7 to 6.3 x 10 ^-6 캜 ^-1 and the moisture barrier layer is made of niobium (Nb), terbium (Tb), magnesium (Mg), aluminum Wherein the thin film layer is formed of an oxide, a nitride, or a nitride oxide of at least one metal selected from the group consisting of Al, Si, and Ga.

delete

The method according to claim 1, wherein the thickness of the primer coating layer is 0.1 to 5 탆; Wherein the moisture barrier layer has a thickness of 20 to 500 nm.

The moisture barrier film according to claim 1, wherein a protective layer is formed on the moisture barrier layer, and the base film, the UV-blocking planarizing primer coating layer, the moisture barrier layer and the protective layer are laminated in order.

The moisture barrier film according to claim 1, wherein two or more repeating units composed of a planarizing primer coating layer and a moisture barrier layer are provided between the base film and the protective layer.

The moisture barrier film according to claim 1, wherein the UV-light having a wavelength of 320 to 380 nm has a transmittance of 10% or less.