Electronic paper barrier film and electronic paper using same

Abstract

Provided is an electronic paper barrier film that has good barrier properties and is capable of suppressing a decrease in the display quality of electronic paper. An electronic paper barrier film 100 comprises a first cover layer 11, a first inorganic oxide layer 12, and a first base material 13 in this order. The average thickness of the first cover layer 11 is 100-600 nm. The standard deviation σ of the thickness of the first cover layer 11 is 3-60 nm.

Description

Barrier film for electronic paper, and electronic paper using the same

[0001] This disclosure relates to a barrier film for electronic paper and electronic paper using the same.

[0002] Electronic paper consumes power only when rewriting information and can maintain its display even after the power supply is cut off, thus reducing power consumption compared to liquid crystal displays and organic EL displays. In addition, electronic paper has excellent characteristics such as "excellent flexibility" and "thin and lightweight."

[0003] Electronic paper is composed of, for example, a back electrode substrate having a back substrate and back electrodes, a transparent electrode substrate having a transparent substrate and transparent electrodes, and a display medium layer disposed between the back electrode substrate and the transparent electrode substrate.

[0004] The display medium layer of electronic paper has a configuration in which dyes are dispersed in a filler liquid, for example. Electronic paper can rewrite the information displayed on it by controlling the voltage to position the desired dyes in the display medium layer towards the observer. The information rewriting performance of the display medium layer is prone to deterioration if the filler liquid evaporates or if moisture from the outside air enters. In addition, to make electronic paper thinner, lighter, and more flexible, a plastic film is often used for at least one of the back substrate and the transparent substrate. Plastic films have inferior barrier properties compared to glass. Therefore, there is a need for plastic films for electronic paper with good barrier properties.

[0005] For example, Patent Documents 1 and 2 have proposed barrier films for electronic paper.

[0006] International Publication No. 2017 / 130617, Japanese Patent Publication No. 2011-240668

[0007] Barrier films for electronic paper require high levels of barrier properties and optical properties. In particular, as the transition from monochrome to color displays has progressed, the requirements for optical properties have become increasingly stringent in recent years. To achieve high levels of barrier properties, the inventors of this invention investigated forming an inorganic oxide layer on a substrate by vapor deposition or the like, and further providing a coating layer on top of the inorganic oxide layer.

[0008] However, when a coating layer is provided on an inorganic oxide layer, although the barrier properties are improved, striped color unevenness can sometimes be seen within the surface of the barrier film. Striped color unevenness degrades the display quality of display devices such as electronic paper. In particular, striped color unevenness becomes extremely noticeable in two-color electronic paper displays, such as black and white. Patent documents 1 and 2 do not address the above-mentioned problems that occur when a coating layer is provided on an inorganic oxide layer.

[0009] This disclosure aims to provide a barrier film for electronic paper that has good barrier properties and can suppress a deterioration in the display quality of electronic paper. Furthermore, this disclosure aims to provide electronic paper using the aforementioned barrier film.

[0010] This disclosure provides the following <1> to <2>. <1> A barrier film for electronic paper having a first coating layer, a first inorganic oxide layer, and a first substrate in this order, wherein the average thickness of the first coating layer calculated in Measurement 1 below is 100 nm or more and 600 nm or less, and the standard deviation σ of the thickness of the first coating layer calculated in Measurement 1 below is 3 nm or more and 60 nm or less. <Measurement 1> A rectangular sample with a short side of 3 cm and a long side of 6 cm is cut from the barrier film for electronic paper. A first line divides the short side of the sample into three equal parts, and a second line divides the long side of the sample into six equal parts. The thickness of the first coating layer is measured at 10 intersections of the first line and the second line. Based on the thickness of the first coating layer at 10 locations, the following are calculated: "the average thickness of the first coating layer," "the standard deviation σ of the thickness of the first coating layer," "the difference between the maximum and minimum thickness of the first coating layer," and "the maximum difference in the thickness of the first coating layer at adjacent measurement locations." <2> Electronic paper including an electronic paper display element and the barrier film described in <1>.

[0011] The barrier film for electronic paper and the electronic paper using the same described herein have good barrier properties and can suppress a deterioration in the display quality of the electronic paper.

[0012] This is a cross-sectional view showing one embodiment of the barrier film for electronic paper of the present disclosure. This is a cross-sectional view showing another embodiment of the barrier film for electronic paper of the present disclosure. This is a cross-sectional view showing one embodiment of electronic paper of the present disclosure. This is a diagram illustrating the measurement location for the thickness of the first coating layer.

[0013] Embodiments of this disclosure are described below. In this specification, the notation "AA to BB" means AA or greater and BB or less. In this specification, "barrier film for electronic paper" may be abbreviated as "barrier film".

[0014] [Barrier Film for Electronic Paper] The barrier film for electronic paper of this disclosure has a coating layer, an inorganic oxide layer, and a first substrate in this order, wherein the average thickness of the coating layer calculated in Measurement 1 below is 100 nm or more and 600 nm or less, and the standard deviation σ of the thickness of the coating layer calculated in Measurement 1 below is 3 nm or more and 60 nm or less. <Measurement 1> A rectangular sample with a short side of 3 cm and a long side of 6 cm is cut out from the barrier film for electronic paper. A first line divides the short side of the sample into three equal parts, and a second line divides the long side of the sample into six equal parts. The thickness of the first coating layer is measured at 10 intersections of the first line and the second line. Based on the thickness of the first coating layer at 10 locations, the "average thickness of the first coating layer", the "standard deviation σ of the thickness of the first coating layer", the "difference between the maximum and minimum values ​​of the thickness of the first coating layer", and the "maximum difference in the thickness of the first coating layer at adjacent measurement locations" are calculated.

[0015] Figures 1 and 2 are cross-sectional views showing embodiments of the barrier film 100 for electronic paper according to the present disclosure. The barrier film 100 in Figures 1 and 2 has a first coating layer 11, a first inorganic oxide layer 12, and a first substrate 13 in that order. The barrier film 100 in Figure 2 further has an adhesive layer 14 and a second substrate 15, and has the first coating layer 11, the first inorganic oxide layer 12, the first substrate 13, the adhesive layer 14, and the second substrate 15 in that order. Figures 1 and 2 are schematic cross-sectional views. That is, in Figures 1 and 2, the scales of each layer constituting the barrier film 100 are schematic for ease of illustration and differ from the actual scales. The same applies to Figure 3.

[0016] <First Substrate> The first substrate can be a resin film containing one or more resins selected from polyester, triacetylcellulose, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyetherketone, acrylic, polycarbonate, polyurethane, and amorphous olefin. Among these resin films, stretched polyester films are preferred from the viewpoint of mechanical strength, dimensional stability, and heat resistance, and biaxially stretched polyester films are more preferred. Examples of polyester films include polyethylene terephthalate film and polyethylene naphthalate film.

[0017] The thickness of the first substrate is preferably 5.0 μm or more, more preferably 8.0 μm or more, and even more preferably 10.0 μm or more. The thickness of the first substrate is preferably 100.0 μm or less, more preferably 75.0 μm or less, and even more preferably 50.0 μm or less. By setting the thickness of the first substrate within the above range, it is easier to improve the handling properties of the barrier film and to make the barrier film thinner.

[0018] In the constituent elements shown in this specification, if there are multiple options for the upper limit and lower limit of a numerical value, the description shall be limited to an embodiment within a range that combines one selected from the upper limit options and one selected from the lower limit options. As a first example, we will consider the description, "Parameter B may be A1 or greater, A2 or greater, or A3 or greater. Parameter B may be A4 or less, A5 or less, or A6 or less." In the first example, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, or A3 or greater and A6 or less. As a second example, we will consider the description, "Parameter C may be A1 or greater and A4 or less, A2 or greater and A5 or less, or A3 or greater and A6 or less." In the second example, the numerical range of parameter C may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less. Furthermore, embodiments of the thickness range of the first substrate described above include 5.0 μm or more and 100.0 μm or less, 5.0 μm or more and 75.0 μm or less, 5.0 μm or more and 50.0 μm or less, 8.0 μm or more and 100.0 μm or less, 8.0 μm or more and 75.0 μm or less, 8.0 μm or more and 50.0 μm or less, 10.0 μm or more and 100.0 μm or less, 10.0 μm or more and 75.0 μm or less, and 10.0 μm or more and 50.0 μm or less.

[0019] In this specification, the thickness of the first substrate and the second substrate (described later) shall be the average of the thicknesses at any 10 locations. The thicknesses of the first and second substrates shall be measured using a general-purpose film thickness measuring instrument. Examples of film thickness measuring instruments include Mitutoyo's Digimatic Standard Outside Micrometer (model number: MDC-25SX).

[0020] In this specification, the thickness of the layer, haze, and b ＊When measuring various parameters such as values, unless otherwise specified, measurements shall be taken in an atmosphere with a temperature of 23°C ± 5°C and a relative humidity of 40% to 65%. Furthermore, before measuring various parameters, the sample shall be exposed to the aforementioned atmosphere for 30 to 60 minutes.

[0021] The first substrate may have an anti-blocking layer containing a matting agent on one side to suppress blocking. General-purpose inorganic particles and organic particles can be used as the matting agent. It is preferable that the anti-blocking layer be placed on the side of the first substrate opposite to the side having the first inorganic oxide layer.

[0022] The surface of the first substrate having the first inorganic oxide layer may be surface-treated to improve adhesion and other properties. Examples of surface treatments include corona discharge treatment, ozone treatment, low-temperature plasma treatment, glow discharge treatment, and oxidation treatment. In addition, an anchor coat layer may be formed on the side of the first substrate having the first inorganic oxide layer to improve adhesion.

[0023] <First Inorganic Oxide Layer> The first inorganic oxide layer preferably contains one or more inorganic oxides selected from aluminum oxide, silicon oxide, and magnesium oxide. To facilitate the improvement of barrier properties and to increase the production efficiency of the barrier film, silicon oxide or aluminum oxide is preferred among the inorganic oxides. In other words, the first inorganic oxide layer preferably contains silicon oxide or aluminum oxide.

[0024] The first inorganic oxide layer can be formed by physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or by chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition. Among these, vacuum deposition is preferred because it offers excellent productivity due to its high deposition rate. Compared to CVD, PVD is preferred because it is less likely to result in carbon contamination in the inorganic oxide layer.

[0025] When the first inorganic oxide layer contains silicon and oxygen, the total content ratio of silicon and oxygen is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and even more preferably 95% by mass or more based on the total solid content of the first inorganic oxide layer. Examples of the inorganic oxide containing silicon and oxygen include silicon oxides (SiO x ) such as silicon dioxide. The inorganic oxide layer containing silicon and oxygen may contain other elements such as carbon as long as it does not inhibit the effects of the optical laminate of the present disclosure. When the first inorganic oxide layer contains aluminum and oxygen, the total content ratio of aluminum and oxygen is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more based on the total solid content of the first inorganic oxide layer. The inorganic oxide containing aluminum and oxygen is Al ２ O ３ Examples of aluminum oxides (AlO x ) include the like. As the inorganic oxide containing aluminum and oxygen, a small amount of aluminum hydroxide may be contained as long as it does not inhibit the effects of the present disclosure.

[0026] The preferred thickness of the first inorganic oxide layer varies depending on the type of the inorganic oxide, and thus cannot be generally stated. When the first inorganic oxide layer contains silicon and oxygen, the thickness of the first inorganic oxide layer is preferably 30 nm or more, more preferably 40 nm or more, and still more preferably 50 nm or more in order to improve the barrier property. When the first inorganic oxide layer contains silicon and oxygen, the thickness of the first inorganic oxide layer is preferably 200 nm or less, more preferably 150 nm or less, and still more preferably 120 nm or less. By setting the thickness to 200 nm or less, it is easy to suppress the occurrence of scratches and cracks in the first inorganic oxide layer, and it is easy to lower the b ＊ value of the barrier film.

[0027] When the first inorganic oxide layer contains aluminum and oxygen, the thickness of the first inorganic oxide layer is preferably 6 nm or more, more preferably 7 nm or more, in order to improve the barrier property. Further, when the first inorganic oxide layer contains aluminum and oxygen, the thickness of the first inorganic oxide layer is preferably 50 nm or less, more preferably 45 nm or less, and still more preferably 40 nm or less. By setting the thickness to 50 nm or less, it is easy to suppress the occurrence of scratches and cracks in the first inorganic oxide layer.

[0028] In this specification, the thicknesses of the first inorganic oxide layer and the adhesive layer described later are calculated from the average value of the values at 10 locations measured from an image of a vertical cross-section taken using, for example, a scanning transmission electron microscope (STEM).

[0029] <First Coating Layer> The barrier film of the present disclosure needs to have a first coating layer on the side opposite to the first base material of the first inorganic oxide layer. By providing the first coating layer in addition to the first inorganic oxide layer, it is easy to enhance the barrier property of the barrier film. The first coating layer is preferably located on the outermost surface of the barrier film.

[0030] The barrier film of the present disclosure requires that the average of the thickness of the first coating layer calculated by the following Measurement 1 is 100 nm or more and 600 nm or less, and the standard deviation σ of the thickness of the first coating layer calculated by the following Measurement 1 is 3 nm or more and 60 nm or less. <Measurement 1> Cut out a rectangular sample of 3 cm in the short side × 6 cm in the long side from the barrier film for electronic paper. Draw a first line that divides the short side direction of the sample into three equal parts, and a second line that divides the long side direction of the sample into six equal parts. Measure the thickness of the first coating layer at 10 intersections of the first line and the second line. Based on the thicknesses of the first coating layer at 10 locations, calculate "the average of the thickness of the first coating layer", "the standard deviation σ of the thickness of the first coating layer", "the difference between the maximum value and the minimum value of the thickness of the first coating layer", and "the maximum value of the difference between the thicknesses of the first coating layer at adjacent measurement locations".

[0031] Figure 4 is a diagram illustrating the measurement locations for the thickness of the first coating layer in Measurement 1. In Figure 4, reference numeral 100A indicates a rectangular sample with a short side of 3 cm and a long side of 6 cm. In Figure 4, the dashed line represents the first line, the dashed line represents the second line, and the black circles with reference numerals X1 to X10 correspond to the intersections of the first and second lines.

[0032] In Measurement 1, the thickness of the first coating layer is measured at 10 points at the intersections of the first and second lines. In Measurement 1, the thickness of the first coating layer at each point is measured from the image of the vertical cross-section of the barrier film captured by a scanning transmission electron microscope. Specifically, the thickness of the first coating layer at each point is measured according to the following procedure A1 to A3.

[0033] A1: Ten small samples are cut from a rectangular sample measuring 3 cm on the short side and 6 cm on the long side. Each small sample is a rectangle measuring 3 mm on the short side and 6 mm on the long side. The direction of the short and long sides of the small samples is aligned with the direction of the short and long sides of the original 3 cm x 6 cm sample. Each small sample is cut so that the intersection points X1 to X10 are located in the center of the plane of each small sample. A2: From each small sample, an imaging sample is prepared in which the vertical cross-section of the barrier film is exposed. The imaging sample is prepared so that the width direction of the vertical cross-section is in the direction of the long side of the small sample. "Vertical cross-section of the barrier film" means a cross-section perpendicular to the XY plane, assuming that the plane of the barrier film is the XY plane. A3: The imaging sample is imaged using a scanning transmission electron microscope to obtain an image of the vertical cross-section of the barrier film. The image is adjusted so that the width of the image area excluding the scale bar is 1200 nm. The thickness of the first coating layer in the image is measured at three locations every 200 nm in the width direction, and the average of these three measurements is taken as the thickness of the first coating layer for each small sample. Then, the thickness of the first coating layer for each small sample is taken as the thickness of the first coating layer at each measurement location.

[0034] The imaging samples for A2 and A3 are prepared, for example, by the following steps B1 to B2. The acceleration voltage for the scanning transmission electron microscope A3 is preferably 100V to 30kV.

[0035] B1: Prepare an embedded sample by embedding a small sample in resin. B2: Prepare an imaging sample by cutting the embedded sample vertically, exposing the vertical cross-section of the barrier film. Cut the embedded sample so that the width direction of the vertical cross-section is in the direction of the long side of the small sample. Cut the embedded sample with a microtome using a diamond knife.

[0036] In B1 above, epoxy resin is preferred for the embedding resin. The embedded sample can be obtained, for example, by placing a small sample in a silicone embedding plate, pouring in the embedding resin, and then, after the embedding resin has hardened, removing the small sample and the embedding resin surrounding it from the silicone embedding plate. The shape of the embedded sample is block-like. The silicone embedding plate is sometimes referred to as a silicone capsule.

[0037] In B2 above, when cutting the embedded sample, it is preferable to cut so as to pass through the center of the small sample. When cutting the embedded sample with a microtome, it is preferable to initially cut the embedded sample roughly, and then finally trim it precisely under the conditions of "SPEED: 1.00 mm / s" and "FEED: 70 nm".

[0038] The barrier film of this disclosure is required to have an average thickness of the first coating layer calculated in Measurement 1 of 100 nm or more and 600 nm or less, and a standard deviation σ of the thickness of the first coating layer calculated in Measurement 1 of 3 nm or more and 60 nm or less. By setting the average thickness and standard deviation σ of the thickness of the first coating layer of the barrier film of this disclosure within the above range, it is possible to achieve good barrier properties and suppress the deterioration of the display quality of electronic paper. The reasons why the barrier film of this disclosure can achieve good barrier properties and suppress the deterioration of the display quality of electronic paper will be explained below.

[0039] First, the barrier film of this disclosure can be made to have good barrier properties by setting the average thickness of the first coating layer to 100 nm or more. Furthermore, the barrier film of this disclosure can be made to have good barrier properties by setting the average thickness of the first coating layer to 600 nm or less, which makes it easier to suppress the occurrence of cracks in the first coating layer and thus easier to suppress the deterioration of barrier properties. However, when the average thickness of the first coating layer was set to 100 nm or more and 600 nm or less, cases of striped color unevenness occurring within the surface of the barrier film occurred frequently. The inventors investigated the cause of striped color unevenness occurring within the surface of a barrier film having a coating layer on an inorganic oxide layer. As a result, the inventors found that "when the average thickness of the first coating layer is 100 nm or more and 600 nm or less, interference is more likely to occur because the thickness is close to the wavelength of light", "if the first coating layer has thickness unevenness within the surface, interference unevenness occurs within the surface", and "striped color unevenness is visible due to interference unevenness within the surface". The inventors have discovered that striped color unevenness can be suppressed by reducing the thickness unevenness of the first coating layer. In other words, the inventors have discovered that a decrease in the display quality of electronic paper can be suppressed by reducing the thickness unevenness of the first coating layer. However, simply reducing the thickness unevenness of the first coating layer sometimes resulted in the first coating layer adhering to other components, which reduced the manufacturing efficiency of the barrier film. Other components include the first substrate and the conveyor rolls of the coating apparatus. Furthermore, when the first coating layer was peeled off from a state in which it was adhering to other components, the barrier properties sometimes decreased due to damage to a part of the first coating layer. As a result of diligent research, the inventors have discovered that the above-mentioned problems can be suppressed by setting the standard deviation σ of the thickness of the first coating layer to a predetermined value or higher. As described above, the barrier film of this disclosure has good barrier properties and can suppress a decrease in the display quality of electronic paper by setting the average thickness and the standard deviation σ of the thickness of the first coating layer within the above range.

[0040] The average thickness of the first coating layer is preferably 120 nm to 570 nm, more preferably 150 nm to 550 nm, more preferably 170 nm to 480 nm, and more preferably 190 nm to 400 nm. The standard deviation σ of the thickness of the first coating layer is preferably 3 nm to 55 nm, more preferably 4 nm to 50 nm, more preferably 4 nm to 40 nm, and more preferably 4 nm to 35 nm.

[0041] The difference between the maximum and minimum thickness of the first coating layer calculated in measurement 1 is preferably 10 nm or more and 200 nm or less, more preferably 15 nm or more and 180 nm or less, and even more preferably 20 nm or more and 150 nm or less. Setting the difference between the maximum and minimum thickness to 10 nm or more makes it easier to suppress the first coating layer from adhering to other components. Setting the difference between the maximum and minimum thickness to 200 nm or less makes it easier to suppress the deterioration of the display quality of the electronic paper. Also, setting the difference between the maximum and minimum thickness to 200 nm or less makes it easier to suppress the localized deterioration of the barrier properties in areas with thin thickness.

[0042] The maximum difference in the thickness of the first coating layer at adjacent measurement locations calculated in Measurement 1 is preferably 5 nm or more and 100 nm or less, more preferably 8 nm or more and 90 nm or less, and even more preferably 10 nm or more and 80 nm or less. Setting the maximum difference in thickness of adjacent measurement locations to 5 nm or more makes it easier to suppress the first coating layer from adhering to other components. Setting the maximum difference to 100 nm or less makes it easier to suppress the deterioration of the display quality of the electronic paper. Also, setting the maximum difference to 100 nm or less makes it easier to suppress the localized deterioration of the barrier properties at thin areas. Adjacent measurement locations mean measurement locations adjacent in the long side direction and / or short side direction. For example, when the reference numeral X1 in Figure 4 is used as the reference, the adjacent measurement locations are X2 and X6, and when the reference numeral X3 in Figure 4 is used as the reference, the adjacent measurement locations are X2, X4 and X8, and so on.

[0043] The coefficient of variation of the thickness of the first coating layer is preferably 0.300 or less, more preferably 0.200 or less, and even more preferably 0.160 or less. The coefficient of variation is a dimensionless parameter obtained by dividing the standard deviation σ by the mean. The coefficient of variation of the thickness of the first coating layer can be expressed by the following formula 1: Coefficient of variation of the thickness of the first coating layer = Standard deviation σ of the thickness of the first coating layer / Mean of the thickness of the first coating layer (Formula 1) By setting the coefficient of variation of the thickness of the first coating layer to 0.300 or less, it is easier to make the shrinkage rate of the first coating layer uniform in the plane, and thus it is easier to suppress the occurrence of cracks in the first coating layer over time due to repeated shrinkage. For this reason, by setting the coefficient of variation of the thickness of the first coating layer to 0.300 or less, it is easier to suppress the decrease in barrier properties over time. There is no particular lower limit to the coefficient of variation of the thickness of the first coating layer, but it is usually 0.010 or more.

[0044] The barrier film can take the form of a single sheet or a roll. When multiple rectangular samples measuring 3 cm on the short side and 6 cm on the long side can be cut from a sheet of barrier film, the percentage of samples in which the "average thickness of the first coating layer" and the "standard deviation σ of the thickness of the first coating layer" satisfy the above-mentioned range is preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, and most preferably 100%. Similarly, the percentage of samples in which the "difference between the maximum and minimum thickness of the first coating layer," the "difference in the thickness of the first coating layer at adjacent measurement points," and the "coefficient of variation of the thickness of the first coating layer" satisfy the above-mentioned range is preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, and most preferably 100%.

[0045] In the case of a roll-shaped barrier film, a rectangular sample measuring 3 cm on the short side and 6 cm on the long side is cut out with the long side of the sample aligned with the width direction of the roll. When multiple rectangular samples measuring 3 cm on the short side and 6 cm on the long side can be cut out in the width direction of the roll, the proportion of samples in which the "average thickness of the first coating layer" and the "standard deviation σ of the thickness of the first coating layer" satisfy the above-mentioned range is preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, and most preferably 100%. Similarly, the proportion of samples in which the "difference between the maximum and minimum values ​​of the thickness of the first coating layer," the "difference in the thickness of the first coating layer at adjacent measurement points," and the "coefficient of variation of the thickness of the first coating layer" satisfy the above-mentioned range is preferably 50% or more, more preferably 70% or more, even more preferably 90% or more, and most preferably 100%. The physical properties of the coating film tend to fluctuate easily in the width direction of the roll, but tend to fluctuate less in the flow direction of the roll. Therefore, the process of cutting multiple rectangular samples measuring 3 cm on the short side and 6 cm on the long side in the width direction of the roll only needs to be performed at predetermined positions in the direction of the roll's flow, and does not need to be performed at all positions in the direction of the roll's flow. However, the physical properties of the coating may vary near the start and end points of the roll. For this reason, the process of cutting multiple samples in the width direction of the roll only needs to be performed, for example, at positions at 10%, 50%, and 90% of the roll's total length.

[0046] The first coating layer preferably contains one or more selected from water-soluble polymers and metal alkoxide compounds. The coating layer more preferably contains one or more selected from water-soluble polymers and metal alkoxide compounds, and even more preferably contains one or more selected from water-soluble polymers and one or more selected from metal alkoxide compounds.

[0047] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, and ethylene-vinyl alcohol copolymers. Among these, polyvinyl alcohol and ethylene-vinyl alcohol copolymers are preferred due to their barrier properties, and polyvinyl alcohol is more preferred. In other words, the coating layer preferably contains one or more selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymers, and more preferably contains polyvinyl alcohol.

[0048] When the first coating layer contains a water-soluble polymer and a metal alkoxide compound, the content of the water-soluble polymer relative to 100 parts by mass of the total amount of the metal alkoxide compound is preferably 5 parts by mass or more and 500 parts by mass or less, more preferably 7 parts by mass or more and 100 parts by mass or less, and even more preferably 8 parts by mass or more and 50 parts by mass or less.

[0049] Examples of metal alkoxide compounds include metal alkoxides, metal alkoxide hydrolysates, and metal alkoxide polymers. Metal alkoxides are M(OR) ｎ It is a compound represented by the general formula , where M represents a metal such as Si, Ti, Al, and Zr, and R represents an alkyl group such as a methyl group and an ethyl group. Specific examples of metal alkoxides include tetramethoxysilane, tetraethoxysilane, and isopropoxyaluminum.

[0050] The first coating layer is preferably substantially free of particles. This is because the presence of particles may result in differences in barrier properties between areas with and without particles. Substantially free means that the amount of particles is 1.0% by mass or less of the total solid content of the first coating layer, more preferably 0.5% by mass or less, more preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and most preferably 0% by mass.

[0051] The first coating layer may contain particles. When the first coating layer contains particles, it is preferable to use particles that do not have polymerizable reactive groups on their surface in order to suppress the occurrence of cracks in the first coating layer. Examples of polymerizable reactive groups include acrylic groups, vinyl groups, epoxy groups, silanol groups, etc.

[0052] The first coating layer can be formed, for example, by applying and drying a coating solution for the first coating layer, which contains the components constituting the first coating layer, onto an inorganic oxide layer. The coating solution may contain additives such as a silane coupling agent, a curing agent, and a dispersant.

[0053] The average thickness of the first coating layer can be adjusted, for example, by the amount of solid content adhering to the coating liquid for the first coating layer. The standard deviation σ of the thickness of the first coating layer can be adjusted, for example, by the methods C1 to C2 below. C1: Viscosity of the coating liquid. Lower viscosity tends to decrease the standard deviation, and higher viscosity tends to increase the standard deviation. Viscosity can be adjusted, for example, by the solid content of the coating liquid. C2: Change in drying temperature. Lower drying temperature tends to decrease the standard deviation, and higher drying temperature tends to increase the standard deviation.

[0054] <Other Layers> The barrier film of this disclosure may have layers other than the first coating layer, the first inorganic oxide layer, and the first substrate. For example, the barrier film of this disclosure may have an anchor coat layer between the first inorganic oxide layer and the first substrate.

[0055] The barrier film of this disclosure further comprises a second coating layer and a second inorganic oxide layer, and the first coating layer, the first inorganic oxide layer, the second coating layer, the second inorganic oxide layer, and the first substrate may be in this order. Embodiments of the second coating layer can be the same as embodiments of the first coating layer. However, since the second coating layer is located on the inside of the barrier film, the range of the standard deviation σ of the thickness, the range of the difference between the maximum and minimum values ​​of the thickness, and the range of the difference in thickness between adjacent measurement locations may be different from embodiments of the first coating layer. Embodiments of the second inorganic oxide layer can be the same as embodiments of the first inorganic oxide layer.

[0056] The barrier film of this disclosure further comprises an adhesive layer and a second substrate, and the coating layer, the inorganic oxide layer, the first substrate, the adhesive layer, and the second substrate may be arranged in this order. The presence of an adhesive layer and a second substrate in the barrier film makes it easier to handle the barrier film.

[0057] <Second Substrate> The second substrate can be a resin film containing one or more resins selected from polyester, triacetylcellulose, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyetherketone, acrylic, polycarbonate, polyurethane, and amorphous olefin. Among these resin films, stretched polyester film is preferred from the viewpoint of mechanical strength, dimensional stability, and heat resistance, and biaxially stretched polyester film is more preferred. Examples of polyester films include polyethylene terephthalate film and polyethylene naphthalate film.

[0058] The second substrate may have a blocking prevention layer containing a matting agent on at least one side of the resin film to suppress blocking. General-purpose inorganic particles and organic particles can be used as the matting agent.

[0059] The thickness of the second substrate is preferably 20.0 μm or more, more preferably 30.0 μm or more, and even more preferably 45.0 μm or more. The thickness of the second substrate is preferably 120.0 μm or less, more preferably 100.0 μm or less, and even more preferably 80.0 μm or less. By setting the thickness of the second substrate within the above range, it is easier to improve the handling properties of the barrier film and to make the barrier film thinner.

[0060] <Adhesive Layer> Examples of adhesives that make up the adhesive layer include moisture-curing adhesives, thermosetting adhesives, UV-curing adhesives, heat-sensitive adhesives (e.g., hot-melt adhesives), and pressure-sensitive adhesives. General-purpose adhesives can be used for these various types of adhesives.

[0061] The adhesive layer is preferably formed from a curing adhesive to ensure good adhesion over the long term. Examples of curing adhesives include moisture-curing adhesives, thermosetting adhesives, and UV-curing adhesives, with thermosetting adhesives and UV-curing adhesives being preferred, and thermosetting adhesives being more preferred.

[0062] Examples of thermosetting adhesives include general-purpose one-component curing adhesives and two-component curing adhesives. Among these, two-component curing polyurethane adhesives are preferred. Two-component curing polyurethane adhesives are adhesives containing polyol compounds and isocyanate compounds.

[0063] The thickness of the adhesive layer is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, and even more preferably 4 μm to 10 μm. A thickness of 2 μm or more makes it easier to improve adhesion to the second substrate. A thickness of 30 μm or less makes it easier to thin the barrier film and also makes it easier to suppress stress caused by curing shrinkage of the adhesive.

[0064] <Physical Properties> The barrier film has a water vapor transmission rate of 0.02 g / m² according to JIS K7129-2:2019. ２ - Preferably less than or equal to 0.01 g / m² ２ - It is more preferable that it be less than or equal to 1 day. The temperature and humidity conditions for measuring water vapor transmission shall be 40°C and 90% relative humidity. In addition, before measuring water vapor transmission, the sample to be measured shall be exposed to an atmosphere of 23°C ± 5°C and a relative humidity of 40% to 65% for 30 to 60 minutes. In this specification, water vapor transmission means the average value of three measured values.

[0065] The barrier film has an oxygen permeability value of 0.5 cc / m² according to JIS K7126-2:2006. ２- It is preferably the following for the day - atm. The temperature and humidity conditions when measuring the oxygen permeability shall be 23°C and a relative humidity of 90%. Also, before measuring the oxygen permeability, the sample for measurement shall be exposed to an atmosphere of 23°C ± 5°C and a relative humidity of 40% or more and 65% or less for 30 minutes or more and 60 minutes or less. In this specification, the oxygen permeability means the average value of three measurement values.

[0066] The barrier film preferably has a total light transmittance of 85% or more according to JIS K7361 - 1:1997, more preferably 87% or more, and even more preferably 89% or more. The upper limit of the total light transmittance is about 95%. In this specification, the total light transmittance means the average value of three measurement values.

[0067] The barrier film preferably has a haze of 20% or less according to JIS K7136:2000, more preferably 15% or less, and even more preferably 10% or less. The lower limit of the haze is not particularly limited, but is usually 0.1% or more. By setting the haze to 20% or less, it is easy to suppress the display of the electronic paper display element from being blurred and visually recognized. In this specification, the haze means the average value of three measurement values. The light incident surface when measuring the total light transmittance and the haze shall be the surface on the first base material side.

[0068] The barrier film is based on the L of the reflected light when the first base material side is the light incident surface with respect to the first inorganic oxide layer ＊ a ＊ b ＊ value of the b value in the color system ＊ is preferably -1.0 or more and 5.0 or less. The b ＊ value is more preferably -0.5 or more and 4.0 or less, and even more preferably -0.1 or more and 3.0 or less. In this specification, the b ＊ value means the average value of three measurement values. The b ＊ By setting the value to 5.0 or less, the yellowish color of the barrier film can be suppressed. By setting the b ＊ value to -1.0 or more, it is easy to suppress the white balance of the background of the electronic paper from being disrupted. In this specification, the b ＊The reflected light used to calculate the value shall be measured to include a specular reflection component, based on geometric condition d of JIS Z8722:2009. <Geometric condition d of JIS Z8722:2009> The sample is irradiated with a single beam of light whose optical axis does not exceed 10° with respect to the normal to the sample surface, and the light reflected in all directions is collected and received. In this case, the irradiated beam of light shall not contain any rays that are tilted at an angle of 5° or more with respect to its center line.

[0069] b of the barrier film mentioned above ＊ The value is the b of the reflected light. ＊ It is a value. Also, light that passes through the barrier film is reflected by the display element. For example, in the case of a barrier film for electronic paper, light that passes through the barrier film is reflected by the electronic paper display element. For this reason, the b of the barrier film ＊ When measuring the value, the reflection of the display element is taken into consideration. Specifically, a sample is prepared in which a perfectly diffusive standard white reflector is placed on the side of the barrier film opposite to the light incident surface, and the b of the barrier film is measured using this sample. ＊ Measure the value. L ＊ a ＊ b ＊ The color system was standardized by the International Commission on Illumination (CIE) in 1976. ＊ a ＊ b ＊ It is based on a color system and is adopted in JIS Z8781-4:2013.

[0070] [Electronic Paper] The electronic paper of this disclosure includes an electronic paper display element and the barrier film of this disclosure described above.

[0071] Figure 3 is a cross-sectional view showing one embodiment of the electronic paper 300 of the present disclosure. The electronic paper 300 in Figure 3 includes an electronic paper display element 200 and a barrier film 100 of the present disclosure. In the electronic paper 300 of Figure 3, the side of the barrier film 100 facing the first coating layer 11 is positioned facing the electronic paper display element 200. In this specification, "the side of the barrier film facing the first coating layer" means the side of the barrier film having the first coating layer, with respect to the first inorganic oxide layer. The barrier film may be positioned so that the side of the barrier film facing the first coating layer is facing the electronic paper display element, or it may be positioned so that the side of the barrier film opposite to the side facing the first coating layer is facing the electronic paper display element.

[0072] A general-purpose electronic paper display element can be used as the electronic paper display element. An example of an electronic paper display element is one having a back electrode substrate having a back substrate and a back electrode, a transparent electrode substrate having a transparent substrate and a transparent electrode, and a display medium layer disposed between the back electrode substrate and the transparent electrode substrate.

[0073] General-purpose back electrode substrates, transparent electrode substrates, and display media layers can be used as the back electrode substrate, transparent electrode substrate, and display media layer. For example, the display media layer can be appropriately selected according to the display method of the electronic paper. Examples of electronic paper display methods include electrophoresis, twist ball, powder transfer, liquid crystal display, and electrochromic methods.

[0074] Preferably, the electronic paper display element and the barrier film of this disclosure are laminated with an adhesive layer in between. The adhesive constituting the adhesive layer can be a general-purpose adhesive.

[0075] The electronic paper of this disclosure may have components other than the electronic paper display element and the barrier film of this disclosure. Examples of components other than the electronic paper display element and the barrier film of this disclosure include a touch panel; a functional film such as an anti-reflective film, an anti-glare film, or a protective film; an adhesive layer; and the like. The touch panel is preferably placed between the electronic paper display element and the barrier film of this disclosure. The functional film is preferably placed on the opposite side of the barrier film of this disclosure from the electronic paper display element. If the electronic paper of this disclosure includes a functional film, the barrier film and the functional film are preferably bonded via an adhesive layer. The functional film and / or adhesive layer preferably contain an ultraviolet absorber.

[0076] This disclosure includes the following <1> to <8>. <1> A barrier film for electronic paper having a first coating layer, a first inorganic oxide layer, and a first substrate in this order, wherein the average thickness of the first coating layer calculated in Measurement 1 below is 100 nm or more and 600 nm or less, and the standard deviation σ of the thickness of the first coating layer calculated in Measurement 1 below is 3 nm or more and 60 nm or less. <Measurement 1> A rectangular sample measuring 3 cm on the short side and 6 cm on the long side is cut from the barrier film for electronic paper. A first line divides the short side of the sample into three equal parts, and a second line divides the long side of the sample into six equal parts. The thickness of the first coating layer is measured at 10 intersections of the first line and the second line. Based on the thickness of the first coating layer at 10 locations, the following are calculated: "the average thickness of the first coating layer," "the standard deviation σ of the thickness of the first coating layer," "the difference between the maximum and minimum thickness of the first coating layer," and "the maximum difference in the thickness of the first coating layer at adjacent measurement locations." <2> The barrier film for electronic paper according to <1>, wherein the difference between the maximum and minimum thickness of the first coating layer calculated in measurement 1 is 10 nm or more and 200 nm or less. <3> The barrier film for electronic paper according to <1> or <2>, wherein the maximum difference in the thickness of the first coating layer at adjacent measurement locations calculated in measurement 1 is 5 nm or more and 100 nm or less. <4> The barrier film for electronic paper according to any one of <1> to <3>, wherein the first coating layer contains one or more selected from water-soluble polymers and metal alkoxide compounds. <5> The barrier film for electronic paper according to any one of <1> to <4>, wherein the first inorganic oxide layer contains silicon oxide or aluminum oxide. <6> A barrier film for electronic paper according to any one of <1> to <5>, further comprising an adhesive layer and a second substrate, wherein the first coating layer, the first inorganic oxide layer, the first substrate, the adhesive layer and the second substrate are arranged in this order. <7> When the first substrate side is the light incident surface with respect to the first inorganic oxide layer, L based on reflected light. ＊ a ＊ b ＊ color system b ＊A barrier film for electronic paper described in any of <1> to <6>, wherein the value is between -1.0 and 5.0. <8> Electronic paper comprising an electronic paper display element and a barrier film described in any of <1> to <7>.

[0077] Next, the present disclosure will be described in more detail by examples, but the present disclosure is not limited in any way by these examples. Unless otherwise specified, "parts" and "%" are based on mass.

[0078] 1. Measurement and Evaluation The following measurements and evaluations were performed on the barrier films for electronic paper of the examples and comparative examples. The evaluations or measurements in 1-1 to 1-5 were carried out in an atmosphere with a temperature of 23°C ± 5°C and a relative humidity of 40% to 65%. In addition, the samples were exposed to the above atmosphere for 30 to 60 minutes before evaluation or measurement.

[0079] 1-1. Thickness of the First Coating Layer A rectangular sample measuring 3 cm on the short side and 6 cm on the long side was cut from near the center of the barrier film of the example and comparative example. The thickness of the first coating layer was measured at 10 locations on the sample according to the procedures A1 to A3 in the main text of the specification. Based on the thickness of the first coating layer at 10 locations, the "average thickness of the first coating layer," the "standard deviation σ of the thickness of the first coating layer," the "difference between the maximum and minimum values ​​of the thickness of the first coating layer," and the "difference in the thickness of the first coating layer at adjacent measurement locations" were calculated.

[0080] 1-2. Total light transmittance and haze: The total light transmittance and haze of the barrier films of the examples and comparative examples were measured using a haze meter (manufactured by Murakami Color Technology Laboratory, product number: HM-150). The light incident surface was the surface on the first substrate side.

[0081] 1-3. b ＊ Samples were prepared by placing a fully diffusing standard white reflector on the first coating layer side of the barrier film of the example and comparative example. The first substrate side of the sample was used as the light incident surface, and L was determined based on the reflected light of the sample. ＊ a ＊ b ＊ color system b ＊The values ​​were measured. The measuring instrument used was a spectrophotometer manufactured by JASCO Corporation (product name: V670), and the following accessories were used: • Accessories: Integrating sphere unit (manufactured by JASCO Corporation, part number: ISN-723) • Light source: Deuterium lamp (190-350 nm), halogen lamp (330-2700 nm) • Measurement spot diameter: 2 mm

[0082] 1-4. Striped Color Unevenness Samples were prepared by laminating the first substrate side of the barrier film of the example and comparative example to a black board (Kuraray Co., Ltd., product name: Comoglass DFA2CG 502K (black), thickness 2 mm) measuring 3 cm on the short side and 6 cm on the long side via a Panac Co., Ltd. optical transparent adhesive sheet (product name: Panaclean PD-S1). The sample was placed on a horizontal table with the first coating layer side facing outwards. The presence of striped color unevenness was evaluated in a bright room environment where the illuminance on the sample surface was between 500 lux and 1000 lux. Twenty adults evaluated the samples and ranked them according to the following criteria: A: Two or fewer people answered that the striped color unevenness was clearly noticeable. B: More than two but five people answered that the striped color unevenness was clearly noticeable. C: More than five but ten people answered that the striped color unevenness was clearly noticeable. D: More than 10 people answered that they could clearly see striped color unevenness.

[0083] 1-5. Ten barrier films of the examples and comparative examples of adhesion between the first coating layer and other components were laminated. Then, a 1000g weight was placed on top and left for 24 hours in an atmosphere of 23°C ± 5°C and a relative humidity of 40% to 65%. After removing the weight, when separating the ten barrier films, the presence or absence of the first coating layer adhering to the adjacent first substrate was evaluated. Those without the first coating layer adhering to the adjacent first substrate were designated as "A", and those with the first coating layer adhering to the adjacent first substrate were designated as "C".

[0084] 1-6. Water Vapor Transmission Rate The water vapor transmission rate was measured for the barrier films for electronic paper in the examples and comparative examples according to JIS K7129-2:2019. The measuring device used was the MOCON ultra-high sensitivity water vapor transmission rate measuring device (product name: AQUATRAN 3) from Hitachi High-Tech Science Co., Ltd. The temperature and humidity conditions for measuring water vapor transmission rate were 40°C and 90% relative humidity. Before measuring water vapor transmission rate, the sample was exposed to an atmosphere of 23°C ± 5°C and a relative humidity of 40% to 65% for 30 minutes. The water vapor transmission rate was 0.02 g / m³. ２ - A score of 7 or less is considered a passing level.

[0085] 2. Fabrication of barrier film for electronic paper [Example 1] A sheet-like biaxially oriented PET film with a thickness of 23 μm was prepared as the first substrate (sheet size: 20 cm x 30 cm). Silicon oxide (SiO₂) was deposited on the first substrate by vacuum deposition. ２ A first inorganic oxide layer (thickness: 70 nm) was formed by depositing a material. Next, the following coating solution for the first coating layer was applied onto the first inorganic oxide layer by gravure printing, and the mixture was heated at 180°C for 60 seconds to form a first coating layer with an average thickness of 300 nm, thereby obtaining the barrier film for electronic paper of Example 1.

[0086] <Preparation of the coating solution for the first coating layer> Solution A was prepared by mixing tetraethoxysilane with a solution (pH 2.2) of water, isopropyl alcohol, and 0.5N hydrochloric acid while cooling it to 10°C. Separately, solution B was prepared by mixing polyvinyl alcohol with a saponification value of 99% or more and isopropyl alcohol. Solution A and solution B were mixed to prepare the coating solution for the first coating layer (solid content: 8% by mass). In the coating solution for the first coating layer, the mass ratio of tetraethoxysilane to polyvinyl alcohol (mass of tetraethoxysilane:mass of polyvinyl alcohol) is 29:4.

[0087] [Examples 2-5] [Comparative Examples 1-4] Except for changing the solid content of the coating solution for the first coating layer, the drying temperature of the coating solution for the first coating layer, and the average thickness of the first coating layer to the values ​​in Table 1, barrier films for electronic paper of Examples 2-5 and Comparative Examples 1-4 were obtained in the same manner as in Example 1.

[0088]

[0089] From the results in Table 1, it can be confirmed that the barrier film of the example has good barrier properties because it has a low water vapor permeability. Furthermore, from the results in Table 1, it can be confirmed that the barrier film of the example can suppress striped color unevenness, thus suppressing the deterioration of the display quality of the electronic paper. Furthermore, from the results in Table 1, it can be confirmed that the barrier film of the example can suppress adhesion between the first coating layer and other components. For this reason, the barrier film of the example can suppress the deterioration of the display quality of the electronic paper caused by adhesion between the first coating layer and other components. On the other hand, the barrier film of Comparative Example 1 did not have sufficient barrier properties because the average thickness of the first coating layer was less than 100 nm. The barrier film of Comparative Example 2 did not have sufficient barrier properties because the average thickness of the first coating layer exceeded 600 nm, making it prone to cracking in the first coating layer. The barrier film of Comparative Example 3 could not suppress adhesion between the first coating layer and other components because the standard deviation σ of the thickness of the first coating layer was less than 3 nm. The barrier film of Comparative Example 4 failed to suppress striped color unevenness because the standard deviation σ of the thickness of the first coating layer exceeded 60 nm. Multiple rectangular samples measuring 3 cm on the short side and 6 cm on the long side can be cut from the barrier films of the Examples and Comparative Examples. The thickness of the first coating layer in Table 1 is the value of the sample cut from near the center of the barrier films of the Examples and Comparative Examples. Although not shown in Table 1, the thickness of the first coating layer of samples cut from other parts of the barrier films of the Examples and Comparative Examples was equivalent to the value in Table 1.

[0090] 11: First coating layer 12: First inorganic oxide layer 13: First substrate 14: Adhesive layer 15: Second substrate 100: Barrier film for electronic paper 200: Electronic paper display element 300: Electronic paper

Claims

1. A barrier film for electronic paper having a first coating layer, a first inorganic oxide layer, and a first substrate in that order, wherein the average thickness of the first coating layer calculated in Measurement 1 below is 100 nm or more and 600 nm or less, and the standard deviation σ of the thickness of the first coating layer calculated in Measurement 1 below is 3 nm or more and 60 nm or less. <Measurement 1> A rectangular sample with a short side of 3 cm and a long side of 6 cm is cut from the barrier film for electronic paper. A first line divides the short side of the sample into three equal parts, and a second line divides the long side of the sample into six equal parts. The thickness of the first coating layer is measured at 10 intersection points of the first line and the second line. Based on the thickness of the first coating layer at 10 locations, the "average thickness of the first coating layer," the "standard deviation σ of the thickness of the first coating layer," the "difference between the maximum and minimum thicknesses of the first coating layer," and the "maximum difference in the thickness of the first coating layer at adjacent measurement points" are calculated.

2. The barrier film for electronic paper according to claim 1, wherein the difference between the maximum and minimum values ​​of the thickness of the first coating layer calculated in measurement 1 is 10 nm or more and 200 nm or less.

3. The barrier film for electronic paper according to claim 1, wherein the maximum value of the difference in thickness of the first coating layer at adjacent measurement locations calculated in measurement 1 is 5 nm or more and 100 nm or less.

4. The barrier film for electronic paper according to claim 1, wherein the first coating layer comprises one or more selected from water-soluble polymers and metal alkoxide compounds.

5. The barrier film for electronic paper according to claim 1, wherein the first inorganic oxide layer comprises silicon oxide or aluminum oxide.

6. The barrier film for electronic paper according to claim 1, further comprising an adhesive layer and a second substrate, wherein the first coating layer, the first inorganic oxide layer, the first substrate, the adhesive layer, and the second substrate are arranged in this order.

7. L based on reflected light when the first substrate side is the light incident surface with respect to the first inorganic oxide layer. ＊ a ＊ b ＊ color system b ＊ A barrier film for electronic paper according to claim 1, wherein the value is between -1.0 and 5.

0.

8. Electronic paper comprising an electronic paper display element and a barrier film according to any one of claims 1 to 7.

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