JP5399196B2 - Gas barrier film and manufacturing method thereof - Google Patents

Description

  The present invention relates generally to gas barrier films used in displays such as LCD (Liquid Crystal Display), organic EL (Electro-Luminescence), and electronic paper, and more specifically, as an electrode film that replaces glass, The present invention relates to a gas barrier film improved so as to have all of properties, transparency, curl, dimensional change and durability. The present invention also relates to a method for producing such a gas barrier film.

  Conventionally, displays such as LCD, organic EL, and electronic paper use glass as an electrode substrate. FIG. 1 shows the structure of an organic EL element using a conventional glass substrate. On the glass substrate 1, an organic EL element portion 4 sandwiched between an upper electrode 3 and a lower electrode 2 is provided. The organic EL element portion 4 is sealed with a sealing metal can 5. A desiccant 6 is placed in the metal can 5 for sealing.

  FIG. 2 shows the structure of an organic EL element using the resin substrate 7. On the resin substrate 7, a moisture-proof barrier film (also referred to as a gas barrier layer) 8 that barriers oxygen and water vapor and protects the organic EL is formed, and an organic EL element sandwiched between the upper electrode 3 and the lower electrode 2 thereon Part 4 is provided. The organic EL element part 4 is covered with a protective film 9 for sealing.

  By using a resin substrate instead of a glass substrate, the element can be made thinner and lighter. By taking advantage of the flexibility of being a resin, it is possible to realize displays of various shapes that are not bound by the conventional frame. There is also a new market need for lightweight, unbreakable and flexible displays. Various heat-resistant films have been studied to cope with this.

  Now, since a polyimide film generally known as a resin substrate has high heat resistance, there is an advantage that it can withstand a high temperature process in the manufacturing process of LCD. However, there is a problem that transparency is poor. A film in which a gas barrier layer is formed using a sputtering method on a PET film is excellent in transparency, but because the PET film has a high water absorption rate, the dimensional change in a humidified environment or a dry heat environment is particularly large. There is a problem such as low durability in humidification, and as an electrode film replacing glass, there is no film having all of heat resistance, transparency, curl, dimensional change, and durability.

The present invention has been made to solve such problems, and provides a method for producing a gas barrier film having all of heat resistance, transparency, curl, dimensional change, and durability as an electrode film replacing glass. The purpose is to do.

Another object of the present invention is to provide a gas barrier film obtained by such a method .

  The present invention has a synergistic effect by forming a silicon oxide film by plasma enhanced chemical vapor deposition on a film made of an addition (co) polymer of a cyclic olefin having a low water absorption and high transparency and a high glass transition temperature. In particular, the inventors have found that the water vapor barrier property can be improved. The inventors have found that the obtained gas barrier film has suitable heat resistance, transparency, curl, dimensional change, and durability as an electrode substrate.

The method for producing a gas barrier film according to the present invention is a method for producing a gas barrier film having a water vapor permeability of 0.3 g / m ² · day or less, wherein the copolymerization ratio of the cyclic olefin and ethylene is from 80:20 to 90:10, the step of preparing a film sheet made of an addition (co) polymer of a cyclic olefin having a glass transition temperature of 170 ° C. or higher, and the initial adhesion strength with the film sheet is 30 g / 10 mm or less, And the process which prepares the adhesive film which has the adhesive strength after 120 degreeC x 10min heat processing as 30 g / 10mm or less and whose thickness is 60 micrometers or less, and which has polyethylene as a main component, The state which bonded the said film sheet and the said adhesive film in, Bei forming a silicon oxide film having a thickness of 30~300nm on the rear surface by plasma enhanced chemical vapor deposition, the That.

On the upper surface of the silicon oxide film, a first hard coat layer having a chemical resistance mainly composed of an ultraviolet curable acrylic resin and a surface hardness of pencil hardness of HB or more is formed, and the surface of the hard coat layer is roughened. the comprises the step of below Ra = 10 nm in arithmetic average, is preferably of.

The adhesive film is removed, and a second hard coat layer is formed on the upper surface of the appearing film sheet. The second hard coat layer has a chemical resistance mainly composed of an ultraviolet curable acrylic resin and a pencil hardness of HB or more. It is preferable to provide a step of setting the curl value to 5 mm or less after standing for 30 minutes in a 160 ° C. environment.

It is preferable to further include a step of forming a transparent electrode having a surface resistance value of 500Ω / □ or less on the first hard coat layer .

A gas barrier film according to another aspect of the present invention is a gas barrier film obtained by the above-described method, and has a water vapor transmission rate of 0.3 g / hour after 24 hours in a measurement environment at 40 ° C. × 100% by a mocon method. m ² · day or less, the water vapor transmission rate after 48 hours is 0.3 g / m ² · day or less, and after standing for 30 minutes in a 160 ° C. environment at 40 ° C. × 100% in the measurement environment, and a water vapor transmission rate of at 24hr elapsed following 0.3g ^/ m 2 · day, the water vapor transmission rate of at 48hr elapsed is below 0.3g ^/ m 2 · day.

  Such a gas barrier film is preferably used for a display or a solar cell.

  The self-adhesive film has the purpose of preventing scratches on the back surface when forming a silicon oxide film on the cyclic olefin film, and the purpose of assisting the film not to break (since the cyclic olefin film is brittle) The film is easily broken by a device for forming a silicon oxide film by plasma chemical vapor deposition by roll-to-roll), and is used for three purposes for winding the processed film without generating blocking or wrinkles.

  According to the gas barrier film of the present invention, suitable heat resistance, transparency, curl, dimensional change and durability as an electrode substrate can be obtained.

It is a figure which shows the structure of the organic EL element using the conventional glass substrate. It is a figure which shows the structure of the organic EL element using a resin substrate. 3 is a cross-sectional view for explaining a process of the method for producing a gas barrier film according to Example 1. FIG.

  The purpose of obtaining a gas barrier film that has all of heat resistance, transparency, curl, dimensional change, and durability as an electrode film that replaces glass, is a cyclic olefin with low water absorption and high transparency, and high glass transition temperature. This was realized by forming a silicon oxide film on a film made of an addition (co) polymer by a plasma chemical vapor deposition method. Embodiments of the present invention will be described below with reference to the drawings.

  A copolymer having a copolymerization ratio of norbornene and ethylene of 82:18 and a glass transition temperature of 180 ° C. was extruded by a melt extrusion method to a thickness of 100 μm to form a film. Next, with reference to FIG. 3 (A), a self-adhesive film 11 composed mainly of polyethylene having a thickness of 50 μm was bonded to one side of the obtained film 10. The adhesion strength was 12 g / 10 mm.

  Next, the silicon oxide film 12 having a thickness of 150 nm is formed on the surface opposite to the surface on which the self-adhesive film 11 is bonded, by attaching it to the feeding roll of the plasma chemical vapor deposition apparatus, A transparent gas barrier film was obtained. Table 1 shows values of water vapor permeability of the obtained transparent gas barrier film. Next, the self-adhesive film 11 was peeled off. The adhesion strength when peeling the self-adhesive film 11 was 22 g / 10 mm.

(Film formation conditions)
・ Deposition rate: 30 m / min
・ Plasma power: 14kW
Reaction gas mixture ratio: hexamethyldisiloxane: oxygen: helium = 1: 3: 1
・ Vacuum degree in vacuum chamber: 0.3 Pa

Next, referring to FIG. 3B, the upper surface of the silicon oxide film 12 is subjected to corona treatment with a processing power of 138 W · min / m ² , and the ultraviolet curable acrylic resin is applied to the upper surface of the silicon oxide film 12. A hard coat agent having a thickness of 5 μm was provided by applying a hard coat agent containing as a main component and curing it with an ultraviolet irradiation device. The pencil hardness of the surface was H, and the arithmetic average of the surface roughness was Ra = 0.6 nm.

The back surface is subjected to corona treatment with a treatment power of 138 W · min / m ² , a hard coat agent mainly composed of an ultraviolet curable acrylic resin is applied to the upper surface, and cured by an ultraviolet irradiation device, Provided a hard coat layer 14 having a thickness of 3 μm. The pencil hardness of the surface was H, and the arithmetic average of the surface roughness was Ra = 0.6 nm. The curl value after leaving the obtained film in a 160 ° C. environment for 30 minutes was 3 mm. The obtained electrode film had a total light transmittance of 92.5% and a haze of 0.15%.

  Further, referring to FIG. 3C, an ITO film (transparent conductive film) is formed on the upper surface laminated with silicon oxide film 12 and hard coat layer 13 by using a sputtering apparatus so that the surface resistance value becomes 250Ω / □. Indium tin oxide) 15 was formed. The shrinkage rate when the obtained electrode film was allowed to stand for 30 minutes in a 160 ° C. environment was MD / TD = 0.08 / 0.05%.

  Further, wet etching was performed to form a pattern on the ITO surface. In the etching process using 5% hydrochloric acid and 25% caustic soda, no defects such as appearance occurred. Further, it was immersed in xylene for 5 minutes, then immersed in toluene for 5 minutes and then dried. There were no defects such as appearance. Table 2 shows the value of water vapor permeability of the obtained film.

  A film was prepared such that the copolymerization ratio of norbornene and ethylene was 82:18, and the copolymerization of cyclic olefin and ethylene having a glass transition temperature of 180 ° C. was made by melt extrusion to a thickness of 150 μm. Next, a self-adhesive film composed mainly of polyethylene having a thickness of 30 μm was bonded to one side. The adhesion strength was 10 g / 10 mm.

  Next, this was mounted on a feeding roll of a plasma chemical vapor deposition apparatus, and a silicon oxide film having a thickness of 180 nm was formed on the surface opposite to the surface on which the self-adhesive film was bonded under the following conditions. Such a transparent gas barrier film was obtained. The value of water vapor permeability of the obtained transparent gas barrier film is shown in Table 1. Then, the self-adhesive film was peeled off. The adhesion strength when peeling the self-adhesive film was 15 g / 10 mm.

(Film formation conditions)
・ Deposition rate: 30 m / min
・ Plasma power: 16kW
・ Reaction gas mixing ratio; hexamethyldisiloxane: oxygen: helium = 1: 3: 3
・ Vacuum chamber vacuum degree: 0.2 Pa

Next, the upper surface of the silicon oxide film is subjected to corona treatment with a treatment power of 138 W · min / m ² , and a hard coat agent mainly composed of an ultraviolet curable acrylic resin is applied to the upper surface of the silicon oxide film. A hard coat layer having a thickness of 5 μm was provided by curing. The pencil hardness of the surface was H, and the arithmetic average of the surface roughness was Ra = 0.8 nm.

The back surface is also subjected to corona treatment with a treatment power of 138 W · min / m ² , a hard coat agent mainly composed of an ultraviolet curable acrylic resin is applied to the upper surface, and the thickness is cured by an ultraviolet irradiation device. A 3 μm hard coat layer was provided. The pencil hardness of the surface was H, and the arithmetic average of the surface roughness was Ra = 0.9 nm. The curl value after the resulting film was allowed to stand for 30 minutes in a 160 ° C. environment was 4 mm. The obtained electrode film had a total light transmittance of 92.1% and a haze of 0.40%.

  Further, an ITO film was formed on the surface opposite to the surface laminated with the silicon oxide film and the hard coat layer by using a sputtering apparatus so that the surface resistance value was 300Ω / □. The contraction rate when the obtained electrode film was allowed to stand for 30 minutes in a 160 ° C. environment was MD / TD = 0.10 / 0.08%.

Further, wet etching was performed to form a stripe pattern having a line width of 10 mm on the ITO surface. In the etching process using 5% hydrochloric acid and 25% caustic soda, no defects such as appearance occurred. Further, it was immersed in xylene for 5 minutes, then immersed in toluene for 5 minutes and then dried. There were no defects such as appearance. Table 2 shows the value of water vapor permeability of the obtained film.
[Comparative Example 1]

  A film was prepared such that the copolymerization ratio of norbornene and ethylene was 77:23, and the copolymerization of a cyclic olefin and ethylene having a glass transition temperature of 140 ° C. was 100 μm in thickness by a melt extrusion method. Next, a self-adhesive film composed mainly of polyethylene having a thickness of 30 μm was bonded to one side. The adhesion strength was 10 g / 10 mm.

Next, this was mounted on a delivery roll of a plasma chemical vapor deposition apparatus, and a silicon oxide film was formed under the same conditions as in Example 1 to obtain a transparent gas barrier film according to this comparative example. Then, the self-adhesive film was peeled off. The adhesion strength when peeling the self-adhesive film was 11 g / 10 mm.
[Comparative Example 2]

A biaxially stretched polyester film (E5100 manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm was used, and this was mounted on a feeding roll of a plasma chemical vapor deposition apparatus, and the corona-treated surface of the film was subjected to the same conditions as in Example 1 above. A silicon oxide film was formed to obtain a transparent gas barrier film.

(Copolymer of cyclic olefin and ethylene)
The water absorption (23 ° C./24 hours) of the copolymer of cyclic olefin and ethylene used in the present invention is usually preferably about 0.005 to 0.1%. If the water absorption rate exceeds 0.1%, the dimensional stability of the resulting substrate tends to decrease.
The refractive index of the copolymer of cyclic olefin and ethylene used in the present invention is usually about 1.49 to 1.55, and the light transmittance is about 93.0 to 90.8%.
Various known additives such as an ultraviolet absorber, an inorganic or organic antiblocking agent, a lubricant, an antistatic agent and a stabilizer may be added to the copolymer of cyclic olefin and ethylene for the purpose.

(Production method)
A method for obtaining a film from a copolymer of a cyclic olefin and ethylene is not particularly limited, and examples thereof include a solution casting method, an extrusion method, and a calendar method.

(Film thickness)
The film of the copolymer of cyclic olefin and ethylene is preferably 20 to 300 μm, and more preferably 40 to 200 μm. If the film strength is too thin, the film strength tends to be insufficient.

(surface treatment)
Surface modification such as flame treatment, UV irradiation treatment, corona discharge treatment, plasma treatment, itro treatment, primer treatment, chemical treatment to improve the wettability and adhesion of the cyclic olefin and ethylene copolymer film surface Processing may be performed. The corona discharge treatment and the ultraviolet irradiation treatment can be performed in air, nitrogen gas, rare gas, or the like. By such surface modification treatment, the wetting tension of the surface of the cyclic olefin resin film is preferably 450 μN / cm (23 ° C.) or more, and more preferably 500 μN / cm (23 ° C.) or more.

(Stretching)
Retardation can be controlled by stretching a copolymer film of cyclic olefin and ethylene. The method is not particularly limited, and examples thereof include a roll stretching method, a tenter clip stretching method, and a rolling method.

(Hard coat)
There is no restriction | limiting in particular in the kind of coating material used for the hard coat provided in the single side | surface or both surfaces of the copolymer film of the cyclic olefin of this invention, and ethylene. Thermosetting or ultraviolet curable hard coat paints such as acrylic, urethane, and silicon that have performance that does not impair optical properties are suitable.
In addition, the hard coat layer can be provided with anti-glare performance as needed for the purpose of preventing reflection of external light when used outdoors. There is no particular limitation on the means for imparting anti-glare performance. For example, a method of forming a hard coat layer by mixing an appropriate amount of silica particles or organic fine particles with the above-mentioned paint, a method of transferring irregularities onto the surface of the hard coat layer Can be used.

(Shrinkage factor)
The shrinkage ratio was measured by measuring the length of four sides of a film cut into a size of 100 × 100 mm in units of 0.001 mm using a high-speed machine, and then measuring the measured film in an oven set at 160 ° C. for 30 minutes. Then, the length of the four sides of the film was measured again in units of 0.001 mm using a high-speed machine, and the amount of change in the length of each of the four sides was determined. Two sheets were measured, the average value was obtained for each of the MD direction and the TD direction, and the shrinkage was obtained. A negative value means contraction, and a positive value means expansion.

(curl)
The distance at which the central part floats from the stage was measured on a flat stage so that the convex surface of the film cut into a size of 100 × 100 mm was on the top.

(Surface resistance value)
The surface resistance value of the ITO film was measured by a 4-terminal 4-probe method using a resistivity meter “Loresta” manufactured by Mitsubishi Chemical Analytech.

  (Water vapor transmission rate)

  The measurement was performed under conditions of 40 ° C. and 100% RH using a PERMATRAN 3/31 manufactured by MOCON.

  The measurement was carried out after 24 hours, 48 hours, after standing for 30 minutes in an environment of 160 ° C., after 24 hours, and after 48 hours.

(Measurement of film thickness of silicon oxide film)
The Si intensity in the unit film was measured using a Rigaku fluorescent X-ray analyzer RIX-2000, and the film thickness of the silicon oxide film was converted from the peak intensity using a calibration curve.

(Surface roughness)
For the surface roughness, Ra value within a 10 × 10 μm square area was measured in contact mode using SPM manufactured by Shimadzu Corporation.

(surface hardness)
It measured according to JIS-K5600-5-4. Measurement was performed at a load of 750 gf.

(Adhesion strength)
The adhesion strength of the adhesive film was measured by peeling at 180 degrees using a peel tester manufactured by HEIDON.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  Since the gas barrier film according to the present invention is excellent in transparency, heat resistance, and gas barrier properties, it can be processed with a roll-to-roll suitable for a transparent substrate of a flexible device, and can be used for a display or a solar cell.

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Lower electrode 3 Upper electrode 4 Organic EL element part 5 Sealing metal can 6 Desiccant 7 Resin substrate 8 Gas barrier layer 9 Sealing protective film 10 Film 11 Self-adhesive film 12 Silicon oxide film 13, 14 Hard coat Layer 15 ITO film

Claims (6)

A method for producing a gas barrier film having a water vapor permeability of 0.3 g / m ² · day or less,
A step of preparing a film sheet made of an addition (co) polymer of a cyclic olefin having a cyclic olefin / ethylene copolymer ratio of 80:20 to 90:10 and a glass transition temperature of 170 ° C. or higher ;
An adhesive film mainly composed of polyethylene having an initial adhesion strength with the film sheet of 30 g / 10 mm or less and an adhesion strength after heat treatment of 120 ° C. × 10 min of 30 g / 10 mm or less and a thickness of 60 μm or less. A preparation process;
A process of forming a silicon oxide film having a thickness of 30 to 300 nm on the back surface of the film sheet and the pressure-sensitive adhesive film by plasma chemical vapor deposition . On the upper surface of the silicon oxide film, a first hard coat layer having a surface hardness of HB or higher and a chemical resistance mainly composed of an ultraviolet curable acrylic resin is formed, and the surface roughness of the hard coat layer is increased. The manufacturing method of the gas barrier film of Claim 1 provided with the process which makes Ra = 10 nm or less by arithmetic mean. The adhesive film is removed, and a second hard coat layer having chemical resistance mainly composed of an ultraviolet curable acrylic resin and a pencil hardness of HB or more is formed on the upper surface of the film sheet that appears. The method for producing a gas barrier film according to claim 2 , further comprising a step of setting the curl value to 5 mm or less after standing for 30 minutes in a 160 ° C environment. The method for producing a gas barrier film according to claim 2, further comprising a step of forming a transparent electrode having a surface resistance value of 500 Ω / □ or less on the first hard coat layer. A gas barrier film obtained by the method according to claim 1,
In a measurement environment at 40 ° C. × 100% by the Mocon method, the water vapor permeability after 24 hours is 0.3 g / m ² · day or less, and the water vapor permeability after 48 hours is 0.3 g / m ² · day. In a measurement environment at 40 ° C. × 100% by the Mocon method after being left in a 160 ° C. environment for 30 minutes, the water vapor transmission rate after 24 hours is 0.3 g / m ² · day or less, A gas barrier film having a water vapor permeability of 0.3 g / m ² · day or less after 48 hours. A display or solar cell using the gas barrier film according to claim 5 .

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