Light-diffusing barrier film

Abstract

Provided is a light-diffusing barrier film. The film is an integral film comprising a barrier layer, a base layer and a light-diffusing layer, sequentially. The film can prevent moisture penetration into a device such as an organic light emitting device, and also imparts a light-diffusing function to the device. In particular, the film can have excellent moisture blocking properties even after a roll-to-roll process.

Claims

1. A light-diffusive barrier film comprising a light-diffusing layer, a base layer and a barrier layer sequentially, wherein a first side (S.sub.1) opposite to a second side of the light-diffusing layer facing the base layer has irregularities with surface roughness (Rt) in a range of 0.1 to 6 μm, wherein the light-diffusing layer is formed from a coating composition comprising 10 parts by weight or more of particles relative to 100 parts by weight of a curable resin, wherein the size of the particles is 500 nm or more, wherein the surface roughness (Rt) means a distance between the highest point (H1) and the lowest point (H2), that is, a height difference (ΔH=H1−H2), when a layer, which is intended to measure the surface roughness, is observed in the direction normal to the surface, wherein a water vapor transmission change rate calculated by the following equation satisfies 30% or less:
Water vapor transmission change rate (%)={(B−A)/A}×100  <Equation> wherein: A is a water vapor transmission rate of the light-diffusive barrier film (F.sub.1); B is another water vapor transmission rate of the light-diffusive barrier film (F.sub.1) measured after applying a constant load on the surface of the barrier layer of the light-diffusive barrier film (F.sub.1) so that the light-diffusing layer irregularity surface of another light-diffusive barrier film (F.sub.2) meets each other, to stack the two film and holding the constant load for 24 hours; the light-diffusive barrier films (F.sub.1, F.sub.2) have the same configuration; and the water vapor transmission rates (A, B) is measured using AQUATRAN 2 (MOCON) under conditions of 38° C. and 100% relative humidity.

2. A light-diffusive barrier film comprising a light-diffusing layer, a base layer and a barrier layer sequentially, wherein a first side (S.sub.1) opposite to a second side of the light-diffusing layer facing the base layer has surface roughness (Rt) of 0.02 μm or more to less than 0.1 μm, and the first side (S1) of the light-diffusing layer with the surface roughness has a sheet resistance of 10.sup.10 Ω/sq or less, wherein the light-diffusing layer is formed from a coating composition comprising 0.1 parts by weight or more of particles relative to 100 parts by weight of a curable resin, wherein the surface roughness (Rt) means a distance between the highest point (H1) and the lowest point (H2), that is, a height difference (ΔH=H1−H2), when a layer, which is intended to measure the surface roughness, is observed in the direction normal to the surface, wherein a water vapor transmission change rate calculated by the following equation satisfies 30% or less:
Water Vapor Transmission Change Rate (%)={(B−A)/A}×100  <Equation> wherein: A is a water vapor transmission rate of the light-diffusive barrier film (F1); B is another water vapor transmission rate of the light-diffusive barrier film (F1) measured after applying a constant load on the surface of the barrier layer of the light-diffusive barrier film (F1) so that the light-diffusing layer irregularity surface of another light-diffusive barrier film (F2) meets each other, to stack the two film and holding the constant load for 24 hours; the light-diffusive barrier films (F1, F2) have the same configuration; and the water vapor transmission rates (A, B) is measured using AQUATRAN 2 (MOCON) under conditions of 38° C. and 100% relative humidity.

3. The light-diffusive barrier film according to claim 2, wherein the light-diffusing layer comprises an antistatic agent.

4. The light-diffusive barrier film according to claim 1, wherein the barrier layer comprises one or more sub-barrier layers.

5. The light-diffusive barrier film according claim 4, wherein the sub-barrier layer has a thickness in a range of 20 to 400 nm.

6. The light-diffusive barrier film according to claim 4, wherein the barrier layer or the sub-barrier layer is a polysilazane layer or a cured layer of the polysilazane layer.

7. The light-diffusive barrier film according to claim 6, wherein the polysilazane has a unit of the following Formula 1: ##STR00002## wherein, R.sup.1, R.sup.2 and R.sup.3 are each independently hydrogen, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkylsilyl group, an alkylamide group or an alkoxy group.

8. The light-diffusive barrier film of claim 1, wherein the light-diffusing layer has a thickness of 20 μm or less.

9. The light-diffusive barrier film of claim 1, wherein the light-diffusing layer, the base layer and the barrier layer are in direct contact with each other.

10. An electric or electronic device comprising the light-diffusive barrier film of claim 1.

11. A method for producing a light-diffusive barrier film of claim 1, comprising: providing a laminate comprising a base layer and a light-diffusing layer, wherein a first side (S.sub.1) opposite to a second side of the light-diffusing layer facing the base layer has surface roughness (Rt) in a range of 0.1 to 6 μm; and applying a barrier layer coating composition on the first side opposite to the second side of the base layer, on which the light-diffusing layer is formed, and then drying it to form a polysilazane layer.

12. A method for producing a light-diffusive barrier film of claim 2, comprising: providing a laminate comprising a base layer and a light-diffusing layer, wherein a first side (S.sub.1) opposite to a second side of the light-diffusing layer facing the base layer has surface roughness (Rt) of 0.02 μm or more and less than 0.1 μm and the first side (S.sub.1) of the light-diffusing layer with the surface roughness has a sheet resistance of 10.sup.10 Ω/sq or less; and applying a barrier layer coating composition on the first side opposite to the second side of the base layer, on which the light-diffusing layer is formed, and then drying it to form a polysilazane layer.

13. The method of claim 11, wherein a light-diffusing layer coating composition comprising 10 parts by weight or more of particles relative to 100 parts by weight of a curable resin is coated on one side of the base layer and then cured to form the light-diffusing layer.

14. The method of claim 11, wherein the barrier layer coating composition comprises a polysilazane of Formula 1: ##STR00003## wherein, R1, R2 and R3 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkylsilyl group, an alkylamide group or an alkoxy group.

15. The method for producing a light-diffusive barrier film according to claim 14, wherein a roll-to-roll process is used, and the method further comprises winding the laminate provided in the first step onto a roll (R1) before applying the barrier layer coating composition.

16. The method of claim 15, wherein the wound laminate is unwound from the roll (R1) for applying the barrier layer coating composition and further comprises winding the light-diffusive barrier film after applying the barrier layer coating composition on a roll (R2) and holding the wound state for 1 hour or longer.

17. The method of claim 16, further comprising unwinding the wound light-diffusive barrier film from the roll (R2) and curing the polysilazane of the barrier layer coating composition and the curing of the polysilazane is performed by plasma treatment or UV light irradiation.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 to 4 schematically show structures of a light-diffusive barrier film according to an embodiment of the present application.

(2) The reference numerals used in the drawings are as follows. 10: barrier layer 11: second sub-barrier layer 12: first sub-barrier layer 20: base layer 30: light-diffusing layer 40: hard coating layer

EXAMPLES

(3) Hereinafter, the present application will be described in detail by way of examples. However, the protection scope of the present application is not limited by the examples as described below.

(4) <Measurement Methods>

(5) For films of Examples and Comparative Examples below, the respective physical properties of Examples and Comparative Examples below as compared were measured as follows.

(6) Method of Measuring Surface Roughness

(7) The surface roughness of the light-diffusing layer surface was measured by a non-contact (vibrating) method using AFM (atomic force microscope) equipment, for example, XE7 equipment from Park Science.

(8) Method of Measuring Sheet Resistance

(9) The produced light-diffusive barrier film was cut to a width of 10 cm and a length of 10 cm to prepare a specimen. Subsequently, using a sheet resistance meter (Hiresta-UP MCP-HT450, Mitsubishi Chemical), the electrode of the meter was pressed at a pressure of 2 kgf, and then the sheet resistance was measured at an applied voltage of 500 V. Three points in the width direction of the specimen were each measured for 10 seconds, and an average value was taken.

(10) Method of Measuring Water Vapor Transmission Rate

(11) (1) Water Vapor Transmission Rate (10.sup.−3 g/m.sup.2day)

(12) The water vapor transmission rates of the light-diffusive barrier films finally prepared in Examples and Comparative Examples were measured using AQUATRAN 2 (MOCON) under 38° C. and 100% relative humidity.

(13) (2) Water Vapor Transmission Change Rate (%)

(14) It was calculated according to the following equation.
Water vapor transmission change rate (%)={(B−A)/A}×100  <Equation>

(15) In Equation above, A is the water vapor transmission rate (in Tables 1 and 2, (i) water vapor transmission rate) of the light-diffusive barrier film finally produced without any blocking process (see Step 4) in Example 1 below) in each of Examples and Comparative Examples, and B is the water vapor transmission rate (in Tables 1 and 2, (ii) water vapor transmission rate) of the light-diffusive barrier film finally produced according to each of Examples and Comparative Examples. Each water vapor transmission rate (A, B) is measured using AQUATRAN 2 (MOCON) under conditions of 38° C. and 100% relative humidity.

(16) Method of Measuring Haze and Light Transmittance

(17) The haze and the light transmittance of the produced light-diffusive barrier film were measured using a haze meter (hm-150, Murakami color research laboratory).

EXAMPLES AND COMPARATIVE EXAMPLES

Example 1

(18) 1) Formation of Light-Diffusing Layer on Base Layer

(19) A light-diffusing layer coating composition containing 20 parts by weight of a photocurable resin relative to a solvent was prepared. Specifically, 80 parts by weight of pentaerythritol triacrylate (PETA) and 20 parts by weight of dipentaerythritol hexaacrylate (DPHA) were dissolved in a solvent (propylene glycol monomethyl ether). To the solution, 4 parts by weight of a polymerization initiator (Irgacure 127, Ciba), 5 parts by weight of an antistatic agent (ELEC ME-2, Kao) and 10 parts by weight of particles (MX80, Soken) having an average particle diameter of 0.8 μm were added to prepare a light-diffusing layer composition.

(20) It was applied on one side of a polyethylene terephthalate (PET) film (T600E50, Mitsubishi) having a thickness of 50 μm by a bar coat (using #5 bar) method. Thereafter, the obtained coating film was heated and dried at 100° C. for 2 minutes, and then subjected to vacuum UV light irradiation using a UV light irradiation line to form a light-diffusing layer having the surface roughness (Rt) described in the following table.

(21) 2) Formation of Hard Coating Layer

(22) With regard to the opposite side of the base film on which the light-diffusing layer was formed, 80 parts by weight of pentaerythritol triacrylate (PETA) and 20 parts by weight of dipentaerythritol hexaacrylate (DPHA) were dissolved in a solvent (propylene glycol monomethyl ether). To the solution, 4 parts by weight of a polymerization initiator (Irgacure 127, Ciba) was added to prepare a hard coating composition. After a coating film was formed on the surface of the base film, on which the light-diffusing layer was not formed, by a bar coat method, it was heated and dried at 100° C. for 2 minutes, and then irradiated with UV rays to form a hard coating layer having a thickness of 1 μm.

(23) 3) Formation of Barrier Layer

(24) Polysilazane (trade name: NL120) was dissolved in dibutyl ether, and then the solution was applied to the surface of the hard coating layer, on which the base film was not formed, by a bar coat method. The obtained coating film was heated and dried at 70° C. for 1 minute and at 130° C. for 2 minutes to form a barrier layer having a thickness of 150 nm (uncured barrier layer formation).

(25) 4) Performing Blocking

(26) The film having the laminated structure of the ‘light-diffusing layer/base layer/hard coating layer/barrier layer’ formed through the above-described processes 1) to 3) is referred to as a first film (F.sub.1). Also, a second film (F.sub.2) was further produced through the same processes as the production of the first film (F.sub.1). A load of 18 kg was applied on the surface of the barrier layer of the first film (F.sub.1) so that the light-diffusing layer irregularity surface of the second barrier film (F.sub.2) met each other to stack the first and second films (F.sub.1, F.sub.2), and the load was maintained for 24 hours. At this time, the first and second films (F.sub.1, F.sub.2) are in a sheet shape, where the size of the contact area is 10 cm×10 cm. The relevant process simulates the process when the light-diffusive barrier film has been wound in the roll-to-roll process.

(27) 5) Curing of Barrier Layer (First Barrier Layer)

(28) The first film (F.sub.1) was subjected to plasma treatment to cure the barrier layer. The plasma treatment was performed under conditions of a flow rate of about Ar:O2=1:1 (on the basis of sccm), a pressure of about 138 mTorr, a power of about 0.27 W/cm.sup.2 and an energy of about 20 J/cm.sup.2. The barrier layer curing was finally performed to produce a light-diffusive barrier film of Example 1.

Example 2

(29) A light-diffusive barrier film of Example 2 was produced in the same manner as in Example 1, except that another coating bar was used at the time of coating the light-diffusing layer composition (#4 bar using). The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Example 3

(30) A light-diffusive barrier film of Example 3 was produced in the same manner as in Example 1, except that no antistatic agent was used and another coating bar was used at the time of coating the light-diffusing layer composition (#3 bar using). The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Example 4

(31) A light-diffusive barrier film of Example 4 was produced in the same manner as in Example 1, except that no antistatic agent was used in the light-diffusing layer composition and particles (GB05S, Aica Kogyo) having an average particle diameter of 5 μm were used instead of the particles used in Example 1 (coated with a #5 bar). The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Example 5

(32) A light-diffusive barrier film of Example 5 was produced in the same manner as in Example 4, except that another coating bar was used at the time of coating the light-diffusing layer composition (#4 bar using). The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Example 6

(33) A light-diffusive barrier film of Example 6 was produced in the same manner as in Example 4, except that another coating bar was used at the time of coating the light-diffusing layer composition (#3 bar using). The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Example 7

(34) A light-diffusive barrier film of Example 7 was produced in the same manner as in Example 6, except that in Process 3), the thickness of the heat-dried barrier layer was changed to 80 nm instead of 150 nm. The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Example 8

(35) The polysilazane composition was coated on the cured barrier layer (first barrier layer) of the light-diffusive barrier film produced in Example 3 and dried in the same manner as in Process 3) described in Example 1. Thereafter, a light-diffusive barrier film of Example 8 comprising a first barrier layer (cured) and a cured second barrier layer (cured) (thickness 150 nm) was produced through Processes 4) and 5) described in Example 1. The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Comparative Example 1

(36) A light-diffusive barrier film of Comparative Example 1 was produced in the same manner as in Example 1, except that particles (MX-2000, Soken) having an average particle diameter of 20 μm were used instead of the particles used in Example 1, a light-diffusing layer coating composition containing 50 parts by weight of the photo-curable resin relative to the solvent was used, no antistatic agent was used and the knife coating was used at the time of coating the light-diffusing layer composition. The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Comparative Example 2

(37) A light-diffusive barrier film of Comparative Example 2 was produced in the same manner as in Example 1, except that no antistatic agent was used in the light-diffusing layer composition. The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Comparative Example 3

(38) A light-diffusive barrier film of Comparative Example 3 was produced in the same manner as in Example 2, except that no antistatic agent was used in the light-diffusing layer composition. The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

Comparative Example 4

(39) A light-diffusive barrier film of Comparative Example 4 was produced in the same manner as in Comparative Example 1, except that in Process 3), the thickness of the heat-dried barrier layer was changed to 80 nm instead of 150 nm. The surface roughness (Rt) value of the light-diffusing layer is shown in the following table.

(40) TABLE-US-00001 TABLE 1 Water vapor transmission rate Light-diffusing (i) upon (ii) upon Water vapor Light-diffusing layer performing no performing transmission layer Rt sheet resistance blocking blocking change rate (μm)* (Ω/sq) (10.sup.−3 g/m.sup.2 day) (10.sup.−3 g/m.sup.2 day) (%)** Example 1 0.025 8.3 × 10.sup.9 3.24 3.38 4.32 Example 2 0.08 7.3 × 10.sup.9 3.31 2.95 10.9 Example 3 0.13   Not measurable*** 2.87 2.43 15.3 Example 4 1.34 Not measurable 3.16 3.56 12.7 Example 5 3.52 Not measurable 3.35 3.18 5.1 Example 6 5.13 Not measurable 2.95 3.64 23.4 C. Exam. 1 8.34 Not measurable 3.48 12 244.8 C. Exam. 2 0.025 Not measurable 3.72 14 276.3 C. Exam. 3 0.08 Not measurable 3.25 18 453.8 *R(t) of the light-diffusing layer is influenced by a particle size, a thickness of the coated product and particle aggregation, and the like. **The water vapor transmission change rate (%) is the percentage change rate between (i) and (ii) values based on the value of (i). ***Not measurable: more than the limit value sheet resistance (10.sup.12 Ω/sq) of the measuring equipment. C. Exam.: Comparative Example

(41) From Examples 3 to 6, it can be seen that the sheet resistance is large because no antistatic agent is used upon forming the light-diffusing layer. However, from the water vapor transmission change rates, it can be seen that the damage of the barrier layer is small in these examples. This is because the surface roughness of the light-diffusing layer is sufficient, so that damage due to generation of static electricity at the interface peeling can be avoided. In Comparative Example 1, since the surface irregularities are too large, the barrier layer is damaged by the irregularities, so that the water vapor transmission change rate is large.

(42) On the other hand, when Examples 1 and 2 are compared with Comparative Examples 2 and 3, it can be seen that even if the surface roughness of the light-diffusing layer exists, in the case of being 0.1 μm or less, there is a limit to reduce the degree of interface adhesiveness between the light-diffusing layer and the barrier layer, and thus it is necessary to adjust the sheet resistance of the light-diffusing layer to a predetermined range.

(43) TABLE-US-00002 TABLE 2 Water vapor transmission rate Light-diffusing (i) upon (ii) upon Water vapor Light-diffusing layer performing no performing transmission layer Rt sheet resistance blocking blocking change rate (μm)* (Ω/sq) (10.sup.−3 g/m.sup.2 day) (10.sup.−3 g/m.sup.2 day) (%)** Example 7 5.13 Not measurable 11.86 13.38 12.8 C. Exam. 4 8.34 Not measurable 11.86 347.74 2,832 *R(t) of the light-diffusing layer is influenced by a particle size, a thickness of the coated product and particle aggregation, and the like. **The water vapor transmission change rate (%) is the percentage change rate between (i) and (ii) values based on the value of (i). ***Not measurable: more than the limit value sheet resistance (10.sup.12 Ω/sq) of the measuring equipment. C. Exam.: Comparative Example

(44) From Table 2 above, it is confirmed that Comparative Example 4 has a high ‘water vapor transmission rate (ii)’ and a high ‘water vapor transmission change rate (%).’ Particularly, the water vapor transmission change rate is much higher than that of the examples. This means that when the surface roughness (Rt) of the light-diffusing layer is excessively large, the barrier layer is damaged by the irregularities of the light-diffusing layer in the wound state. That is, the results of Example 7 and Comparative Example 4 suggest that it is important to prevent damage to the barrier layer in the roll-to-roll process even when the thickness of the barrier layer that has the greatest effect on the water vapor transmission rate of the film is the same.

(45) TABLE-US-00003 TABLE 3 Water vapor Light transmission rate Haze transmittance Barrier layer (10.sup.−3 g/m.sup.2 day) (%) (%) Example 3 Single layer 2.43 86.5 89.1 Example 8 Two layers 0.02 86.6 86.5

(46) Table 3 above shows that the water vapor transmission rate decreases as a number of barrier layers are included (that is, comprising two or more sub-barrier layers) regardless of the presence or absence of blocking. Specifically, even if the second barrier layer is further formed on the first barrier layer after the blocking is performed, it can be confirmed that excellent moisture blocking properties (low water vapor transmission rate) are secured according to Examples of the present application.