JP5245094B2 - Gas barrier film - Google Patents

Description

  The present invention relates to a gas barrier film having high transparency and excellent barrier properties against water vapor.

  Conventionally, in an electronic display device such as a display or a touch panel, a glass substrate has been used. However, there is a problem that the glass substrate is cracked, heavy, or not bent. Therefore, in recent years, a flexible substrate constituted by using a resin base material has been developed instead of the glass substrate.

  However, unlike a glass substrate, a resin base material has a property of easily allowing water vapor to pass therethrough, and there is a problem that deterioration of an electronic device is likely to occur unless such gas permeation is sufficiently suppressed.

  In order to solve such a problem, conventionally, as a film having a high gas barrier property, an aluminum vapor-deposited film, a film obtained by vapor-depositing a metal oxide, or the like is known (for example, see Patent Document 1).

Japanese Patent Publication No.53-12953

  However, in the case of an aluminum vapor-deposited film, if sufficient gas barrier properties are ensured, the film has a very low transparency, so that there is a problem that it cannot be used for a device that requires transparency.

Moreover, in the case of the film which vapor-deposited the metal oxide thin film, although transparency became higher than an aluminum vapor deposition film, there existed a problem that gas barrier property was inadequate.
In addition, there are films that improve gas barrier properties by laminating multiple organic or inorganic layers over 4 layers, but the problem is that if the number of layers increases excessively, the manufacturing process becomes complicated and expensive. was there.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a gas barrier film having sufficiently high transparency and excellent barrier properties against water vapor.

Hereinafter, the configuration employed in the present invention will be described.
The gas barrier film of the present invention is a layer formed by coating a transparent film-like resin base material and a resin composition on one surface of the resin base material, and the surface roughness after the coating is JIS B The flattening layer that is flattened to Ra ≦ 2.5 nm with the arithmetic average roughness Ra specified in 0601-2001, and the flattening layer side after the flattening layer is formed on the resin base material The surface roughness is an arithmetic average roughness Ra specified in JIS B 0601-2001, Ra ≦ 2.5 nm, the contact angle of water on the surface is 55 degrees or more, and The oxygen amount x includes an SiO _x layer in a range of 1.6 ≦ x <2.0.

  In the gas barrier film of the present invention, a resin film that can ensure sufficient transparency may be used as the resin base material. For example, a polyester resin film such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate may be used. it can. Moreover, as long as transparency is ensured, film materials other than polyester resin may be used, for example, polyolefin resin such as polyethylene and polypropylene, polyamide resin such as nylon 6 and nylon 12, polyvinyl alcohol and ethylene-vinyl alcohol copolymer. A film made of a synthetic resin such as polystyrene, triacetyl cellulose, acrylic, polyvinyl chloride, polycarbonate, polyimide, polyethersulfone, cyclic polyolefin, or the like can be used. Among them, a polyethylene terephthalate film is preferable in terms of high transparency, high mechanical strength, and excellent dimensional stability. Although the thickness of the resin base material may vary depending on the application, it is preferable that the thickness considered to be general in practice is about 25 to 188 μm.

  In the gas barrier film of the present invention, the planarization layer is a layer that planarizes the surface of the resin substrate by being formed on the surface of the resin substrate. As the resin composition for forming the flattening layer, any resin composition can be used as long as the flattening as defined in the present invention can be realized and the transparency of the resin base material is not excessively impaired. Can be used.

  As an example of such a resin composition, for example, an energy ray curable acrylic resin composition can be given. In addition, examples of the energy rays here include ultraviolet rays and electron beams.

  As the energy ray curable acrylic resin composition, a composition in which an acrylic photopolymerizable prepolymer, a photopolymerizable monomer or the like is a main component and a photopolymerization initiator is further added can be used. .

  Examples of the acrylic photopolymerizable prepolymer include urethane acrylate, polyester acrylate, epoxy acrylate, and melamine acrylate. Examples of the acrylic photopolymerizable monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, Lauryl (meth) acrylate, stearyl (meth) acrylate, allyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (Meth) acrylate, glycerol (meth) acrylate, glycidyl (meth) acrylate, benzyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (2-e Xoxyethoxy) ethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, 2- Mention of methoxypropyl (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxytripropylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, etc. Can do.

  Examples of the photopolymerization initiator include benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, and benzoin isobutyl ether; acetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2 -Hydroxy-2-methyl-phenylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, etc. Acetophenones; anthraquinones such as 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-chloroanthraquinone, 2-amylanthraquinone; 2,4-diethylthioxanthone, 2-isopropyl Thioxanthones such as thioxanthone and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone, 4-benzoyl-4′-methyldiphenyl sulfide and 4,4′-bismethylaminobenzophenone; And phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. Specifically, from the market, Irgacure 184 (1-hydroxycyclohexyl phenyl ketone) and Irgacure 907 (2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane manufactured by Ciba Specialty Chemicals, Inc. -1-one), Lucylin TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) manufactured by BASF, etc. can be easily obtained. Moreover, you may use these individually or in mixture of 2 or more types.

  In order to perform the planarization treatment on the surface of the resin base material by coating the resin composition as described above, it is desirable to form a coating layer having a thickness of about 1 to 10 μm as the planarization treatment layer. If the thickness of the planarization layer is less than 1 μm, it becomes difficult to perform the planarization as expected. On the other hand, even if the thickness of the planarization layer exceeds 10 μm, further planarization cannot be expected, which is wasteful in terms of resources and economy.

Furthermore, in the gas barrier film of the present invention, the SiO _x layer is a layer for developing gas barrier properties. Such SiO _x layer can be formed by sputtering, physical vapor deposition techniques such as ion plating.

This SiO _x layer is formed on the surface on the side of the planarization layer after the planarization layer is formed on the resin substrate. As a result, this SiO _x layer also becomes a layer having a very flat surface, and the surface roughness is Ra ≦ 2.5 nm with the arithmetic average roughness Ra specified in JIS B 0601-2001. It becomes possible. The surface roughness of the SiO _x layer is preferably as smooth as possible, and the lower limit thereof is not particularly limited as long as the arithmetic average roughness Ra is 2.5 nm or less.

Further, the surface of the SiO _x layer preferably has a low affinity with water, and as an index, the contact angle of water on the surface of the SiO _x layer is preferably 55 degrees or more. When this contact angle is less than 55 degrees, the affinity with water increases, so that the barrier property against water vapor tends to decrease. In addition, if this contact angle is 55 degree | times or more, an upper limit will not be specifically limited.

Furthermore, in the SiO _x layer, it is also important that the oxygen amount x is in the range of 1.6 ≦ x <2.0. When this amount of oxygen is less than 1.6, when it is 2.0 or more, any gas barrier property tends not to be as high as expected.

According to the gas barrier film of the present invention configured as described above, the SiO _x layer having the characteristics defined in the present invention is formed on the resin substrate whose surface has been previously planarized by the planarization treatment layer. Therefore, it becomes a gas barrier film having a gas barrier performance much higher than that of the conventional product.

Details of the gas barrier performance will be apparent from experimental examples and the like to be described later. However, according to the gas barrier film of the present invention, the water vapor permeability is extremely high, that is, less than 0.02 g / m ² / day.

  Therefore, in various applications where high water vapor barrier properties are required, such as a wide range of applications such as optical members, electronics members, general packaging members, and medicine packaging members, the gas barrier film of the present invention can be used to protect the object to be protected from water vapor. Can be protected.

Sectional drawing which expands and shows a part of gas barrier film demonstrated as embodiment of this invention.

Next, an embodiment of the present invention will be described with an example.
[1] Structure of Gas Barrier Film A gas barrier film 1 illustrated in FIG. 1 is a film having a three-layer structure in which a resin base material 2, a planarization treatment layer 3, and a SiO _x layer 4 are laminated.

The resin base material 2 is a film made of a polyester resin (in this embodiment, made of polyethylene terephthalate), and in this embodiment, the thickness is set to 125 μm.
The flattened layer 3 is obtained by coating the resin substrate 2 with an ultraviolet curable acrylic resin composition and irradiating the resin substrate 2 with ultraviolet rays, and curing the thickness in the present embodiment. Is 6 μm.

  Further, the planarization layer 3 is a layer having a very smooth surface, and the surface roughness is an arithmetic average roughness Ra specified in JIS B 0601-2001, and Ra = 1.1 nm. In this embodiment, this surface roughness was measured using an atomic force microscope (AFM; Atomic Force Microscope, manufactured by KEYENCE, VN-8010).

  Specifically, for measurement, first, a sample film is affixed to glass and then set on a measurement table. As measurement conditions, measurement mode: DFM (dynamic force microscope), scan area: 200 μm × 200 μm, scan speed: Auto was set and AFM measurement was performed. And after correcting the inclination of the AFM image obtained by this measurement, the surface roughness measurement based on JISB0601-2001 method was implemented. In addition, about this measurement, 3 points | pieces were implemented per sample and the average value was employ | adopted as measurement data.

The SiO _x layer 4 is a layer formed on the surface of the flattening treatment layer 3 side by sputtering after the flattening treatment layer 3 is formed on the resin base material 2. In this embodiment, the thickness of the SiO _x layer 4 is Is 50 to 75 nm.

Sputtering for forming the SiO _x layer 4 was carried out by attaching a film (= the one in which the planarizing layer 3 is formed on the resin base material 2) to a roll-to-roll type sputtering apparatus. Further, silicon (manufactured by Sumitomo Metal Mining Co., Ltd.) was attached to the dual magnetron cathode provided in the sputtering apparatus as a sputtering target material.

To start sputtering, first, the vacuum chamber of the sputtering apparatus is depressurized with a vacuum pump and evacuated until the pressure in the vacuum chamber reaches 4 × 10 ⁻⁴ Pa. It was introduced into the vacuum chamber while controlling the flow rate with a flow controller.

  After introducing the discharge gas, the argon gas flow rate is adjusted so that the pressure in the vacuum chamber is 0.4 Pa, and an arbitrary film formation output is supplied to the cathode using a discharge power source (PE-II, manufactured by Advanced Energy). Then, pre-sputtering was performed.

Then, when 10 minutes passed from the start of pre-sputtering, oxygen gas as a reaction gas was introduced into the vacuum chamber while controlling the flow rate with a mass flow controller. After the oxygen gas was introduced, the oxygen gas flow rate was adjusted to an arbitrary discharge voltage. Then, the flow rates of argon gas and oxygen gas were reduced so that the final film forming pressure would be 0.4 Pa, and the desired SiO _x layer 4 was formed while conveying the film.

[2] Physical property / performance measurement About the gas barrier film 1 mentioned above, the physical property and performance were measured. In measuring physical properties and performance, a number of samples having different physical properties were prepared by changing the production conditions, screening was performed on those samples, and samples having excellent performance were selected.

Evaluation items of physical properties and performance measurement include (A) surface roughness Ra of the planarization layer 3, (B) oxygen amount x in the SiO _x layer 4, (C) surface roughness Ra of the SiO _x layer 4, (D) The contact angle of water on the surface of the SiO _x layer 4 and (E) moisture permeability were selected, and these measurements were performed.

  Among these evaluation items, for (A) and (C), the arithmetic average roughness Ra was measured according to JIS B 0601-2001 by the method described above. For (B), ESCA (ESCA5400, manufactured by ULVAC-PHI) was used, and as the X-ray source, an Mg anode (output 400 W, tube voltage 14 kV) was used, the measurement range was 0.8 mmφ, Si: 2p, O The measurement was performed in a range where a peak corresponding to a binding energy of 1 s appears. The obtained measurement results were analyzed with software (MultiPak, manufactured by ULVAC-PHI) attached to the ESCA apparatus. At this time, the background of Shirley is removed for each peak, the sensitivity coefficient of each element is corrected for the peak area, and the atomic ratio is obtained. With respect to the obtained atomic ratio, the number of O atoms was calculated by setting the number of Si atoms to 1. Three points were measured per sample, and the average value was adopted as the oxygen amount x.

  For (D), using an automatic contact angle meter (DM-500, manufactured by Kyowa Interface Science Co., Ltd.), a sample film is affixed to a slide glass, set on the base of the automatic contact angle meter, and 1 μL of distilled water is added. After dropping, the contact angle after 3 seconds was measured. In addition, about this contact angle, 5 points | pieces per sample were measured and the average value was employ | adopted as measurement data.

  About (E), it measured based on JISK7129B in the environment of a temperature of 40 degreeC, and a relative humidity of 90% using the water-vapor-permeation tester (PERMATRAN W3 / 33, the product made by MOCON).

In addition to the above evaluation items, the thickness of the SiO _x layer 4 and the total light transmittance were also measured. The total light transmittance was measured according to JIS K 7136 method using a haze meter (HZ-2, Suga test machine). Some representative samples are extracted and the measurement results and the like for these samples are shown in Table 1.

In Table 1, the samples shown as Examples 1 to 3 had a moisture permeability of not more than the measurement guaranteed value of the measuring apparatus (0.02 g / m ² / day or less), and showed extremely high water vapor barrier properties.
On the other hand, the sample shown as Comparative Example 1 has a relatively rough surface roughness of the planarization layer 3 of 9.0 nm and a relatively rough surface roughness of the SiO _x layer 4 of 9.4 nm. Comparative Example 1 did not show a water vapor barrier property as high as expected.

  Therefore, in order to further verify this result, experiments were repeated by changing the surface roughness of the planarization layer 3. And when the experimental result was verified, it turned out that about the surface roughness of the planarization process layer 3 has not ensured sufficiently high water vapor | steam barrier property regarding the sample exceeding 2.5 nm at least.

However, as also shown in Comparative Examples 2 to 6, since a sufficiently high water vapor barrier property may not be ensured even in a sample having a surface roughness of the planarization layer 3 of 2.5 nm or less, this point is further improved. Study was carried out. Specifically, the surface roughness of the SiO _x layer 4 was also variously changed and further experiments were repeated, and the experimental results were verified.

As a result, it was found that the surface roughness of the SiO _x layer 4 was not able to ensure a sufficiently high water vapor barrier property for a sample having at least 2.5 nm. In this regard, in Comparative Examples 1 to 6 illustrated in Table 1, except for Comparative Example 5, the surface roughness of the SiO _x layer 4 exceeds 2.5 nm. It can be seen that the water vapor barrier property is not so high.

On the other hand, as for Comparative Example 5, although the surface roughness of the SiO _x layer 4 was 2.5 nm or less, Examples 1 to 3 did not show a high water vapor barrier property. Therefore, further in this respect, when a lot of experimental results were verified, when the contact angle of water was less than 55 degrees, there was a tendency that a sufficiently high water vapor barrier property could not be secured.

This tendency is also observed in the samples illustrated in Table 1. For example, in Examples 1 to 3, the contact angles of water on the surface of the planarization layer 3 are 62 degrees, 60 degrees, and 64 degrees, respectively. It is a large angle of 55 degrees or more. On the other hand, in the case of the comparative example 5 described above, the surface roughness of the SiO _x layer 4 is 2.5 nm or less, but the contact angle of water is 51 degrees, which is less than 55 degrees.

Furthermore, during the verification as described above, it was found that the oxygen amount x of the SiO _x layer 4 also has a tendency to affect moisture permeability. Specifically, when the oxygen amount x is less than 1.6 (for example, Comparative Example 6), there is a tendency that the water vapor barrier property is lowered (that is, the moisture permeability is increased).

  If the oxygen amount x is 1.6 or more, the water vapor transmission rate can be sufficiently reduced, and the desired water vapor barrier property can be exhibited. In particular, the oxygen amount x is 1.8 or more. For example, the water vapor transmission rate could be significantly reduced (for example, Examples 1 to 3).

  However, the larger the amount of oxygen x, the better, and when the amount of oxygen x is 2.0 or more, the water vapor barrier property tends to decrease (for example, Comparative Examples 3 to 5). In particular, as shown in Comparative Example 3, when the oxygen amount x was 2.2 or more, the water vapor barrier property tended to be remarkably lowered.

Therefore, in order to ensure a sufficiently high water vapor barrier property in consideration of the above-described tendency, first, the planarization treatment layer 3 is planarized to a surface roughness of 2.5 nm or less, and SiO _x. It is considered preferable to flatten the surface roughness of the layer 4 to a level of 2.5 nm or less. For the SiO _x layer 4, the production conditions (for example, the processing time during sputtering and the discharge voltage) are adjusted so that the contact angle of water on the surface is 55 degrees or more, and the oxygen amount x is 1 When adjusted so that it is 6 or more and less than 2.0, it is considered that a sufficiently high water vapor barrier property is exhibited.

[3] Modifications and the like Although the embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment described above, and can be implemented in various other forms.

  For example, in the said embodiment, although the film made from a polyethylene terephthalate was shown as an example of the resin base material 2, other polyester resin films can also be used, for example, using films, such as a polybutylene terephthalate and a polyethylene naphthalate. Also good. In addition, if there is no problem in required transparency and mechanical strength, a film material other than polyester resin may be used. For example, polycarbonate, polyethylene, polypropylene, polystyrene, triacetyl cellulose, acrylic, polyvinyl chloride, etc. These films may be used as the resin base material 2.

  Moreover, in the said embodiment, although the ultraviolet curable acrylic resin composition was illustrated as a resin composition which forms the planarization process layer 3, it coats with an electron beam curable resin composition in addition to this. Also, the desired planarization layer 3 can be formed. Moreover, even if it is other than the energy ray curable coating composition that is cured by such ultraviolet rays or electron beams, by applying to the resin substrate surface, if the resin substrate surface can be planarized, The planarization layer 3 can be formed using any resin composition.

Furthermore, in the above embodiment, to form a SiO _x layer 4 by sputtering, it is also possible to form by other physical vapor deposition techniques, for example, by an ion plating method, intended SiO _x Layer 4 may be formed.

In addition, in the above embodiment, the resin base material 2, planarization layer 3, and SiO _x layer 4, the respective thicknesses, have been exemplified specific values for the thickness of these layers, the gas barrier film It suffices if it is appropriately adjusted according to the use of 1.

1 ... gas barrier film, 2 ... resin substrate 3 ... planarization layer, 4 ... SiO _x layer.

Claims (3)

A transparent film-like resin substrate;
It is a layer formed by coating a resin composition on one surface of the resin base material, and the surface roughness after coating is the arithmetic average roughness Ra specified in JIS B 0601-2001, Ra ≦ 2. A planarization layer that planarizes to 5 nm;
After the planarization layer is formed on the resin substrate, the layer is formed on the surface on the planarization layer side, and the surface roughness is an arithmetic average roughness defined in JIS B 0601-2001. An SiO _x layer in which Ra is Ra ≦ 2.5 nm, the contact angle of water on the surface is 55 ° or more, and the oxygen amount x is in the range of 1.6 ≦ x <2.0. Gas barrier film. The gas barrier film according to claim 1, wherein the resin composition forming the planarization treatment layer is an energy ray curable acrylic resin composition. The gas barrier film according to claim 1, wherein the resin base material is a polyester resin film.