Barrier film for display device and display device using the same

Abstract

Provided is a barrier film for display devices that has good barrier properties and can suppress deterioration in the display quality of the display device even when silicon oxide is used. [Solution] A barrier film for a display device, which has a substrate, an inorganic oxide layer, and an overcoat layer in this order, wherein the inorganic oxide layer contains silicon oxide and has a thickness of 30 nm or more, and the overcoat layer contains an acrylic resin and has a thickness of more than 2.0 μm.

Description

[Technical Field]

[0001] The present disclosure relates to a barrier film for a display device and a display device using the same. [Background technology]

[0002] Electronic paper consumes power only when information is rewritten and can maintain display even after power supply is stopped, so it consumes less power than liquid crystal displays and organic electroluminescence (EL) displays. Electronic paper also has excellent properties such as being "excellent flexibility" and "thin and light."

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

[0004] The display medium layer of electronic paper is, for example, configured by dispersing a pigment in a filler liquid. Electronic paper allows information displayed on the electronic paper to be rewritten by placing a desired pigment in the display medium layer on the viewer side through voltage control. The display medium layer's information rewriting performance is prone to deterioration when the filler liquid evaporates or moisture from the outside air invades. Furthermore, electronic paper often uses a plastic film for at least one of the rear substrate and the transparent substrate to achieve thinner, lighter, and more flexible electronic paper. Plastic films have inferior barrier properties compared to glass. Therefore, a plastic film with good barrier properties is required for electronic paper. Plastic films with improved barrier properties may also be required for display devices other than electronic paper, such as organic EL display devices and liquid crystal display devices using wavelength conversion sheets.

[0005] For this reason, barrier films have been developed in which a layer with good barrier properties is formed on a plastic film. Barrier films for display devices have been proposed, for example, in Patent Document 1. Patent Documents 1 and 2 disclose barrier films having a vapor deposition layer on a substrate and further having a coating layer containing a hydrolyzate of alkoxysilane or the like on the vapor deposition layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-202602 [Patent Document 2] Japanese Patent Application Publication No. 2019-188721 Summary of the Invention [Problem to be solved by the invention]

[0007] Barrier films for display devices such as electronic paper are required to have high barrier properties and good visibility. In order to achieve high barrier properties, the present inventors have investigated using silicon oxide as a material for the barrier layer of barrier films for display devices such as electronic paper, and increasing the thickness of the barrier layer containing silicon oxide.

[0008] Increasing the thickness of the barrier layer containing silicon oxide can improve the barrier properties of the barrier film. However, when the thickness of the barrier layer containing silicon oxide is increased, a minute ring-shaped rainbow pattern may be visible in part of the surface of the barrier layer. The rainbow pattern reduces the display quality of display devices such as electronic paper. In particular, the rainbow pattern is extremely noticeable in black and white electronic paper. Patent Documents 1 and 2 do not consider at all the above-mentioned problems that arise when the thickness of the barrier layer containing silicon oxide is increased.

[0009] An object of the present disclosure is to provide a barrier film for a display device that has good barrier properties and can suppress deterioration in the display quality of the display device even when a silicon oxide is used, and to provide a display device using the barrier film for a display device. [Means for solving the problem]

[0010] The present disclosure provides the following [1] to [2]. [1] A substrate, an inorganic oxide layer, and an overcoat layer in this order; the inorganic oxide layer contains silicon oxide and has a thickness of 30 nm or more; The barrier film for a display device, wherein the overcoat layer contains an acrylic resin and has a thickness of more than 2.0 μm. [2] A display device comprising the barrier film for a display device according to [1] above. [Effects of the Invention]

[0011] The barrier film for a display device of the present disclosure and the display device using the same have good barrier properties and can suppress deterioration in display quality. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing one embodiment of a barrier film for a display device according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view showing another embodiment of the barrier film for a display device of the present disclosure. [Figure 3] FIG. 1 is a cross-sectional view showing an embodiment of electronic paper according to the present disclosure. [Figure 4] This is an optical microscope image of a ring-shaped rainbow pattern. [Figure 5] 1 is an optical microscope image of a barrier film according to an embodiment of the present disclosure taken from a planar direction. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described. In this specification, the "barrier film for a display device" may be abbreviated as "barrier film".

[0014] [Barrier film for display devices] The barrier film for a display device of the present disclosure comprises: The film has a substrate, an inorganic oxide layer, and an overcoat layer in this order, the inorganic oxide layer contains silicon oxide and has a thickness of 30 nm or more; The overcoat layer contains an acrylic resin and has a thickness of more than 2.0 μm.

[0015] 1 and 2 are cross-sectional views showing one embodiment of a barrier film 100 of the present disclosure. The barrier film 100 of Figures 1 and 2 has a substrate 11, an inorganic oxide layer 12, and an overcoat layer 14, in that order. The barrier film 100 of Figure 2 has a coating layer 13 between the inorganic oxide layer 12 and the overcoat layer 14. In Fig. 1, the inorganic oxide layer 12 and the overcoat layer 14 are in contact with each other. In Fig. 2, the inorganic oxide layer 12 and the coating layer 13 are in contact with each other, and the coating layer 13 and the overcoat layer 14 are in contact with each other. 1 and 2 are schematic cross-sectional views. That is, in Fig. 1 and Fig. 2, the scale of each layer constituting the barrier film 100 is shown in a simplified manner for ease of illustration, and differs from the actual scale. The same is true for Fig. 3.

[0016] <Features of the barrier film of the present disclosure> The main features of the barrier film of the present disclosure are that it has the following configurations (1) to (3). (1) It has a substrate, an inorganic oxide layer, and an overcoat layer in this order. (2) The inorganic oxide layer contains silicon oxide and has a thickness of 30 nm or more. (3) The overcoat layer contains an acrylic resin and has a thickness of more than 2.0 μm.

[0017] The reasons why the above configurations (1) to (3) can improve the barrier properties and prevent the display quality of the display device from deteriorating will be explained below. As described above in (2), the inorganic oxide layer of the barrier film of the present disclosure contains silicon oxide and has a thickness of 30 nm or more. By using silicon oxide as the inorganic oxide constituting the inorganic oxide layer, it is possible to prevent the price of the barrier film from increasing. Furthermore, by making the thickness of the inorganic oxide 30 nm or more, it is possible to impart high barrier properties to the barrier film. However, when an inorganic oxide layer containing silicon oxide is formed by a vacuum deposition method or the like, minute black dots may be visible on the inorganic oxide layer. For example, minute black dots are formed on an inorganic oxide layer formed by a vacuum deposition method due to a splash phenomenon. Since minute black dots are partial defects that occur during film formation, the longer the film formation time, the more likely they are to occur within the surface of the barrier film. In other words, the thicker the inorganic oxide layer containing silicon oxide, the more likely they are to occur within the surface of the barrier film. Although efforts have been made to reduce the splash phenomenon in vacuum deposition, even at the time of filing the present application, it has not been possible to completely eliminate the splash phenomenon. As such, it is difficult to completely eliminate minute black dots. On the other hand, even if tiny black dots appear on the barrier film, the barrier properties are unlikely to be significantly affected. This is due to the above-mentioned configuration (1). That is, when an overcoat layer is provided on the inorganic oxide layer, defects in the inorganic oxide layer are filled with the overcoat layer, which is thought to make it easier to maintain the desired barrier properties. However, in barrier films having the above configurations (1) and (2), minute ring-shaped rainbow patterns may be visible in parts of the surface of the barrier layer. That is, barrier films having the above configurations (1) and (2) are excellent in that they are low-cost and easily achieve high barrier properties, but minute ring-shaped rainbow patterns may be visible. The minute ring-shaped rainbow patterns are a factor that reduces the display quality of display devices. In particular, rainbow patterns are very noticeable in black and white two-color electronic paper. However, the barrier film of the present disclosure, by having the above-mentioned configuration (3) in addition to the above-mentioned configurations (1) and (2), can suppress the visibility of the minute ring-shaped rainbow pattern, and therefore the barrier film of the present disclosure can suppress the degradation of the display quality of the display device. The reason why the provision of the above configuration (3) can prevent the display quality of the display device from deteriorating will be explained below.

[0018] In order to enhance the barrier properties of an inorganic oxide layer, a layer that covers the inorganic oxide layer may be formed on the inorganic oxide layer. In Patent Documents 1 and 2, a coating layer containing an alkoxysilane hydrolysate is formed on a vapor-deposited inorganic oxide layer. The layer formed on the inorganic oxide layer is usually thin, as long as it has a thickness that enhances the barrier properties. The present inventors have discovered that when a thin overcoat layer is formed on an inorganic oxide layer on which minute black dots have been generated by the splash phenomenon, a minute ring-shaped rainbow pattern is generated. Figure 4 is an optical microscope image of the minute ring-shaped rainbow pattern. The black area in the center of Figure 4 is a minute black dot generated by the splash phenomenon. The inorganic oxide layer exhibits height variations centered on the black dots. The height variations in the inorganic oxide layer are typically between 0.1 μm and 3.0 μm. Therefore, when a thin overcoat layer is formed on an inorganic oxide layer with black dots, thickness variations occur in the overcoat layer centered on the black dots. Since interference is more likely to occur the closer the wavelength of light, thickness variations in a thin overcoat layer cause interference variations. Thus, it is believed that the ring-shaped rainbow pattern results from interference variations caused by thickness variations in a thin overcoat layer. The thickness variations in the overcoat layer occur over a wider area than the black dots. Therefore, as shown in Figure 4, the size of the ring-shaped rainbow pattern is larger than the size of the black dots. The barrier film of the present disclosure, by incorporating the above-described feature (3), can suppress the visibility of minute ring-shaped rainbow patterns. The feature (3) stipulates that the thickness of the overcoat layer must be greater than 2.0 μm. By increasing the thickness of the overcoat layer to greater than 2.0 μm, even if thickness unevenness occurs in the overcoat layer centered on the minute black dots in the inorganic oxide layer, the thickness is sufficiently thicker than the wavelength of light, making it less likely to cause interference unevenness. Therefore, the feature (3) can suppress the visibility of minute ring-shaped rainbow patterns. In other words, the barrier film of the present disclosure suppresses the visibility of minute ring-shaped rainbow patterns by intentionally increasing the thickness of the overcoat layer. Figure 5 is an optical microscope image of the barrier film of the present disclosure captured from a planar direction. In the optical microscope image of Figure 5, no ring-shaped rainbow patterns are observed around the minute black dots. The above configuration (3) further specifies that the overcoat layer contains an acrylic resin. Silicon oxide, a typical example of silicon oxide, and acrylic resin have relatively similar refractive indices. Therefore, when the overcoat layer contains an acrylic resin, interference is less likely to occur, making it easier to prevent the visibility of minute ring-shaped rainbow patterns. In addition, acrylic resins have good moisture resistance and light resistance. Therefore, when the overcoat layer contains an acrylic resin, it is easier to maintain the barrier properties of the barrier film over a long period of time.

[0019] <Barrier film laminate structure> Examples of layered structures of the barrier film of the present disclosure include the following (1) to (4). In the following (1) to (4), " / " means the interface between layers. The barrier film of the present disclosure may have layers other than the substrate, anchor coat layer, inorganic oxide layer, coating layer, and overcoat layer, as long as the effects of the present disclosure are not impaired. (1) Substrate / inorganic oxide layer / overcoat layer (2) Substrate / inorganic oxide layer / coating layer / overcoat layer (3) Substrate / anchor coat layer / inorganic oxide layer / overcoat layer (4) Substrate / anchor coat layer / inorganic oxide layer / coating layer / overcoat layer

[0020] The barrier film of the present disclosure preferably has no other layer on the side of the overcoat layer opposite to the inorganic oxide layer. In other words, the barrier film of the present disclosure preferably has the overcoat layer as the outermost layer. By adopting the above-described configuration, the occurrence of a ring-shaped rainbow pattern can be suppressed without excessively increasing the thickness of the barrier film. In order to prevent damage to the outermost overcoat layer, a protective film that can be peeled off at room temperature may be attached to the overcoat layer. The protective film is peeled off when the film is incorporated into a display device. "Peellable" means that the peel strength when peeling the protective film from the overcoat layer is 1.5 N / 25 mm or less.

[0021] <Base material> The substrate is preferably a resin film having optical transparency. Examples of the resin film include resin films containing one or more resins selected from polyester, triacetyl cellulose, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, acrylic, polycarbonate, polyurethane, and amorphous olefin. Among these resin films, stretched polyester films are preferred, and biaxially stretched polyester films are more preferred, from the viewpoints of mechanical strength, dimensional stability, and heat resistance. Examples of polyester films include polyethylene terephthalate films and polyethylene naphthalate films.

[0022] The substrate may be a single layer of a resin film, or may be a laminate of a plurality of resin films bonded together. A substrate having a plurality of resin films laminated together may be a laminate of the resin films bonded together directly, or may be a laminate of the resin films bonded together via an adhesive layer.

[0023] The thickness of the substrate is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more. By making the thickness of the substrate 5 μm or more, it is easier to improve the strength of the barrier film. From the viewpoint of thinning the substrate and making it easier to suppress the intrusion of water vapor and oxygen from the edges, the thickness of the substrate is preferably 200 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, more preferably 75 μm or less, and more preferably 50 μm or less.

[0024] In the configuration requirements described herein, when multiple upper and lower limit options are shown, it is assumed that the range described is a combination of one selected from the upper limit options and one selected from the lower limit options. For example, embodiments of the thickness range of the above-mentioned substrate include 5 μm to 200 μm, 5 μm to 150 μm, 5 μm to 100 μm, 5 μm to 75 μm, 5 μm to 50 μm, 8 μm to 200 μm, 8 μm to 150 μm, 8 μm to 100 μm, 8 μm to 75 μm, 8 μm to 50 μm, 10 μm to 200 μm, 10 μm to 150 μm, 10 μm to 100 μm, 10 μm to 75 μm, and 10 μm to 50 μm.

[0025] In this specification, the thickness of each layer constituting the barrier film, such as the thickness of the substrate, the thickness of the overcoat layer, the thickness of the inorganic oxide layer, etc., refers to the average value of the thickness measured at 20 points on a cross-sectional image taken with a scanning transmission electron microscope, excluding the minimum and maximum values, and 18 points.

[0026] In this specification, the layer thickness, haze, b * Unless otherwise specified, the measurement of various parameters such as the value shall be carried out in an atmosphere at a temperature of 23°C ± 5°C and a relative humidity of 40% to 65%. Furthermore, before measuring the various parameters, the sample shall be exposed to the atmosphere for 30 minutes to 60 minutes.

[0027] The substrate preferably has a total light transmittance according to JIS K7361-1:1997 of 80% or more, more preferably 85% or more, and even more preferably 87% or more. The substrate preferably has a haze according to JIS K7136:2000 of 10% or less, more preferably 5% or less, and even more preferably 2% or less.

[0028] The surface of the substrate on which the inorganic oxide layer is formed may be subjected to a surface treatment in order to improve adhesion, etc. Examples of the surface treatment include corona discharge treatment, ozone treatment, low-temperature plasma treatment, glow discharge treatment, and oxidation treatment.

[0029] <Inorganic oxide layer> The inorganic oxide layer must contain silicon oxide. Furthermore, the inorganic oxide layer must have a thickness of 30 nm or more. By including silicon oxide as the inorganic oxide constituting the inorganic oxide layer, it is possible to suppress an increase in the price of the barrier film. By making the thickness of the inorganic oxide 30 nm or more, it is possible to impart high barrier properties to the barrier film. Silicon oxide is an oxide containing silicon. A typical example of silicon oxide is silicon oxide (SiOx) such as silicon dioxide. That is, the inorganic oxide layer preferably contains silicon oxide.

[0030] The total content of silicon and oxygen in the inorganic oxide layer is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more. The inorganic oxide layer may contain elements other than silicon and oxygen as long as the effects of the present disclosure are not impaired.

[0031] In order to improve the barrier properties, the thickness of the inorganic oxide is preferably 40 nm or more, more preferably 50 nm or more, and even more preferably 60 nm or more. If the inorganic oxide layer is too thick, cracks tend to occur in the inorganic oxide layer. Furthermore, when the inorganic oxide layer reaches a certain thickness, the barrier properties tend to saturate. Therefore, the thickness of the inorganic oxide layer is preferably 200 nm or less, more preferably 150 nm or less, even more preferably 120 nm or less, and even more preferably 100 nm or less. The barrier film preferably has only one inorganic oxide layer.

[0032] The inorganic oxide layer can be formed by, for example, physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating; chemical vapor deposition (CVD) methods such as plasma enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Among these, vacuum deposition is preferred because it has a high deposition rate and is therefore highly productive. PVD is preferred because it is less likely to introduce carbon into the inorganic oxide layer than CVD.

[0033] <Overcoat layer> The overcoat layer is disposed on the side of the inorganic oxide layer opposite the substrate. When a coating layer (described later) is not present between the inorganic oxide layer and the overcoat layer, the overcoat layer is preferably in contact with the inorganic oxide layer. When a coating layer (described later) is present between the inorganic oxide layer and the overcoat layer, the overcoat layer is preferably in contact with the coating layer.

[0034] The overcoat layer must contain an acrylic resin and have a thickness of more than 2.0 μm. By making the overcoat layer thicker than 2.0 μm, even if thickness unevenness occurs in the overcoat layer centered around tiny black dots in the inorganic oxide layer, interference unevenness is less likely to occur. Therefore, by making the overcoat layer thicker than 2.0 μm, minute ring-shaped rainbow patterns can be suppressed. By making the overcoat layer contain an acrylic resin, interference is more unlikely to occur, making it easier to suppress minute ring-shaped rainbow patterns. Furthermore, by making the overcoat layer contain an acrylic resin, the barrier properties of the barrier film can be more easily maintained over a long period of time.

[0035] The thickness of the overcoat layer is preferably 2.5 μm or more, more preferably 3.0 μm or more, and even more preferably 4.0 μm or more. If the thickness of the overcoat layer is too thick, winding defects such as blocking may occur during winding and production efficiency may decrease. Therefore, the thickness of the overcoat layer is preferably 40.0 μm or less, more preferably 30.0 μm or less, even more preferably 20.0 μm or less, and even more preferably 10.0 μm or less.

[0036] The acrylic resin is a polymer containing, as a monomer component, at least one ethylenically unsaturated monomer having a carboxyl group or a carboxylic acid ester group selected from the group consisting of methacrylic acid, acrylic acid, methacrylic acid esters, and acrylic acid esters. The acrylic resin may have functional groups other than the carboxyl group and the carboxylic acid ester group, such as a urethane group, as long as the effects of the present disclosure are not impaired. The content of the acrylic resin is preferably 30% by mass or more of the total solid content of the overcoat layer, more preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, and more preferably 80% by mass or more.

[0037] To facilitate suppression of blocking, the acrylic resin preferably has a glass transition temperature of 40° C. or higher, more preferably 60° C. or higher, and even more preferably 80° C. or higher. The upper limit of the glass transition temperature is about 200° C.

[0038] The overcoat layer may contain particles to suppress blocking, but preferably does not substantially contain particles, because if particles aggregate, the visibility of the particle-aggregated areas will change from that of other areas, resulting in a deterioration in display characteristics. "Substantially free" means that the content is 1.0% by mass or less of the total solid content of the overcoat layer, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and most preferably 0% by mass.

[0039] The overcoat layer is preferably non-adhesive to prevent blocking. In this specification, a non-adhesive layer refers to a layer in which a ball does not stop in the measurement section for 5 seconds or more under the conditions of "inclination angle: 20°" and "ball number: No. 1" in the inclined ball tack test of JIS Z0237:2022. "Inclination angle: 20°" is the smallest inclination angle specified in the test. "Ball number: No. 1" is the smallest ball specified in the test, with a diameter of approximately 0.8 mm.

[0040] The overcoat layer may contain additives such as a silane coupling agent, an antioxidant, and an ultraviolet absorber. The overcoat layer can be formed, for example, by applying a coating liquid containing components constituting the overcoat layer onto the inorganic oxide layer and drying it.

[0041] It is preferable to reduce the viscosity of the coating liquid for the overcoat layer. By reducing the viscosity of the coating liquid for the overcoat layer, it is possible to more easily prevent the elevation difference near the black dots of the inorganic oxide layer from being reflected in the overcoat layer. Therefore, by reducing the viscosity of the coating liquid for the overcoat layer, it is possible to more easily prevent the ring-shaped rainbow pattern from being observed. By reducing the solid content of the coating liquid for the overcoat layer, it is possible to more easily reduce the viscosity of the coating liquid for the overcoat layer.

[0042] <Coating layer> The barrier film may have a coating layer between the inorganic oxide layer and the overcoat layer. By having the coating layer, it is possible to more easily improve the barrier properties. When the coating layer is provided, it is preferred that the inorganic oxide layer and the coating layer are in contact with each other, and that the coating layer and the overcoat layer are in contact with each other.

[0043] The coating layer preferably contains one or more selected from a water-soluble polymer and a metal alkoxide compound. Of the water-soluble polymer and the metal alkoxide compound, the coating layer more preferably contains one or more selected from the water-soluble polymer, and even more preferably contains one or more selected from the water-soluble polymer and one or more selected from the metal alkoxide compound.

[0044] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, and ethylene-vinyl alcohol copolymers, and among these, polyvinyl alcohol and ethylene-vinyl alcohol copolymers are preferred for their barrier properties, with polyvinyl alcohol being more preferred. That is, the coating layer preferably contains one or more selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymers, and more preferably contains polyvinyl alcohol.

[0045] When the coating layer contains a water-soluble polymer and a metal alkoxide-based compound, the content of the water-soluble polymer relative to 100 parts by mass of the total amount of the metal alkoxide-based 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.

[0046] Examples of the metal alkoxide-based compound 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: In the formula, M represents a metal such as Si, Ti, Al, or Zr, and R represents an alkyl group such as a methyl group or an ethyl group. Specific examples of metal alkoxides include tetramethoxysilane, tetraethoxysilane, and isopropoxyaluminum.

[0047] In order to improve the barrier properties, the thickness of the coating layer is preferably 70 nm or more, more preferably 100 nm or more, and even more preferably 150 nm or more. The thickness of the coating layer is preferably 600 nm or less, more preferably 480 nm or less, more preferably 370 nm or less, and even more preferably 300 nm or less. By setting the thickness to 600 nm or less, the barrier film can be made thinner and the occurrence of cracks in the coating layer can be easily suppressed.

[0048] The coating layer may contain additives such as a silane coupling agent, a curing agent, and a dispersant. The coating layer can be formed, for example, by applying a coating liquid containing components constituting the coating layer onto the inorganic oxide layer and drying it.

[0049] <Anchor coat layer> The barrier film may have an anchor coat layer between the substrate and the inorganic oxide layer. By having the anchor coat layer, the adhesion of the inorganic oxide layer is improved, which makes it easier to improve the barrier properties. When the anchor coat layer is present, it is preferred that the substrate and the anchor coat layer are in contact with each other, and that the anchor coat layer and the inorganic oxide layer are in contact with each other.

[0050] The anchor coat layer preferably contains a resin such as a thermoplastic resin or a thermosetting resin, etc. The proportion of the resin to the total solid content of the anchor coat layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0051] The resin may be one or more selected from thermoplastic resins such as polystyrene resins, polyolefin resins, ABS resins, AS resins, AN resins, polyphenylene oxide resins, polycarbonate resins, polyacetal resins, polyethylene terephthalate resins, polybutylene terephthalate resins, polysulfone resins, polyphenylene sulfide resins, acrylic resins, and cellulose resins; and thermosetting resins such as oxazoline group-containing resins. Among these, a mixed resin of an oxazoline group-containing resin and a thermoplastic resin is preferred. The mass ratio of the oxazoline group-containing resin to the thermoplastic resin (oxazoline group-containing resin:thermoplastic resin) is preferably 5:95 to 80:20, more preferably 10:90 to 70:30. Examples of the oxazoline group-containing resin include those described in JP-A-11-179836.

[0052] The thickness of the anchor coat layer is preferably 0.005 μm or more and 5 μm or less, more preferably 0.008 μm or more and 3 μm or less, and even more preferably 0.01 μm or more and 1 μm or less.

[0053] The anchor coat layer may contain additives such as antioxidants and leveling agents within a range that does not impair the effects of the present disclosure. The anchor coat layer can be formed, for example, by applying a coating liquid containing components constituting the anchor coat layer onto the substrate and drying it.

[0054] The total thickness of the barrier film is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and is preferably 180 μm or less, more preferably 150 μm or less, and even more preferably 130 μm or less. By making the total thickness of the barrier film 10 μm or more, the barrier film can be made easier to handle, and by making the total thickness of the barrier film 180 μm or less, it is easier to make display devices such as electronic paper thinner. In this specification, the total thickness of the barrier film is the average value of the 18 measurements taken at 20 locations, excluding the minimum and maximum values. The total thickness at each measurement location is measured using a general-purpose film thickness measuring device. Examples of film thickness measuring devices include Mitutoyo's Digimatic Standard Outside Micrometer (product number: MDC-25SX).

[0055] <Physical properties> The barrier film has a water vapor permeability of 0.02 g / m according to JIS K7129-2:2019. 2 ·day or less, and 0.01 g / m 2 It is more preferable that it is less than 1 day. The temperature and humidity conditions for measuring the water vapor permeability are 40°C and a relative humidity of 90%. Prior to measuring the water vapor permeability, the sample to be measured is exposed to an atmosphere at a temperature of 23°C ± 5°C and a relative humidity of 40% to 65% for 30 to 60 minutes. In this specification, the water vapor permeability refers to the average value of three measurements.

[0056] The barrier film has an oxygen permeability of 0.5cc / m according to JIS K7126-2:2006. 2 ·day·atm or less is preferable. The temperature and humidity conditions for measuring oxygen permeability are 23°C and 90% relative humidity. Prior to measuring oxygen permeability, the sample to be measured is exposed to an atmosphere at a temperature of 23°C ± 5°C and a relative humidity of 40% to 65% for 30 to 60 minutes. In this specification, oxygen permeability refers to the average value of three measurements.

[0057] The barrier film preferably has a total light transmittance according to JIS K7361-1:1997 of 80% or more, more preferably 85% or more, and even more preferably 87% or more. The upper limit of the total light transmittance is about 95%. In this specification, the total light transmittance refers to the average value of three measurements. The barrier film preferably has a haze according to JIS K7136:2000 of 10% or less, more preferably 5% or less, and even more preferably 2% or less. The lower limit of haze is about 0.1%. In this specification, haze refers to the average value of three measurements. When measuring the total light transmittance and haze, the light incident surface is the surface on the substrate side.

[0058] The barrier film reduces the L caused by reflected light when the overcoat layer side is the light incident surface. * a * b * Color space b * It is preferable that the value is between -1.0 and 5.0. * The value is more preferably -0.5 or more and 4.0 or less, and further preferably -0.1 or more and 3.0 or less. * Values ​​represent the mean of three measurements. Barrier film b * The larger the value, the thicker the inorganic oxide layer containing silicon oxide tends to be. * By setting the value to -1.0 or more, it is possible to easily improve the barrier properties. * By setting the value to 5.0 or less, it is possible to suppress the yellowish color from becoming too strong, and therefore it is possible to more easily suppress the deterioration of the display quality of the display device. In this specification, b * The reflected light from which the value is calculated shall be measured to include a specular reflection component based on the geometric condition d of JIS Z8722:2009. <Geometric condition d of JIS Z8722:2009> The sample is irradiated with a single light beam whose optical axis does not exceed 10° with respect to the normal of the sample surface, and the light reflected in all directions is collected and received. Also, in this case, the irradiation light beam shall not include a light beam having an inclination of 5° or more with respect to its center line.

[0059] The b of the above-described barrier film * value is the b of the reflected light * value. Also, the light transmitted through the barrier film is reflected by the display element. For example, in the case of a barrier film for an electronic paper, the light transmitted through the barrier film is reflected by the electronic paper display element. Therefore, when measuring the b of the barrier film * value, the measurement is made taking into account the reflection of the display element. Specifically, a sample is prepared by arranging a standard white reflecting plate of perfect diffusion on the surface opposite to the light incident surface of the barrier film, and the b of the barrier film is measured using the sample. * value. L * a * b * The color system is based on the L * a<000​​​​​​​​​​​​​​This is the average number of hits.]

[0061] As described above, when a ring-shaped rainbow pattern occurs centered on a tiny black dot, the ring-shaped rainbow pattern occurs over a wider area than the tiny black dot. Therefore, a barrier film that satisfies formula (1) suppresses the occurrence of a ring-shaped rainbow pattern. In formula (1), black dots with a maximum diameter of 100 μm or more are counted because small dots with a maximum diameter of less than 100 μm are less noticeable even if a rainbow pattern occurs. In formula (1), black dots with a maximum diameter of 2000 μm or less are counted because black dots with a maximum diameter of more than 2000 μm are unlikely to occur, and a portion including black dots with a maximum diameter of more than 2000 μm is unsuitable for use as a barrier film. In formula (1), Y / X is preferably 0.5 or less, more preferably 0.2 or less, even more preferably 0.1 or less, and most preferably 0. Y / X being 0 means that X exceeds 0 while Y is 0. X varies depending on how much splashing is to be suppressed, but is usually 1 particle / m 2 More than 100 pieces / m 2 The following is the result.

[0062] The maximum diameter of each black dot is measured according to the following steps A1 to A3. The number of ring-shaped rainbow patterns formed around a black dot and extending beyond the black dot is determined by placing a black plate on the substrate side of the cut sample A3 below and observing with a magnifying glass. Observation is carried out in a bright room environment where the illuminance on the surface of the cut sample is between 500 lux and 1000 lux.

[0063] A1: Place a black board and a barrier film on a horizontal table in that order. Place the barrier film on top of the black board with the substrate side facing the black board. A2: In a bright room environment where the illuminance on the barrier film surface is between 500 lux and 1000 lux, observe the presence of black dots with a magnifying glass. A3: A cut sample is prepared by cutting out the area where black dots and ring-shaped rainbow patterns are confirmed from the barrier film. A planar photograph is taken with an optical microscope from the side of the cut sample opposite the substrate. The maximum diameter of the black dot is calculated from the planar photograph obtained. The maximum diameter of the black dot means the maximum distance between two parallel lines when the black dot is sandwiched between the two lines.

[0064] The barrier film of the present disclosure can be used in displays such as electronic paper, liquid crystal displays, EL displays such as organic EL displays and inorganic EL displays, plasma displays, LED displays such as mini LED and micro LED display elements, etc. Liquid crystal displays include liquid crystal displays using a wavelength conversion sheet.

[0065] [Display device] The display device of the present disclosure includes the above-described barrier film for a display device of the present disclosure.

[0066] Examples of the display device include electronic paper, liquid crystal display devices, EL display devices such as organic EL display devices and inorganic EL display devices, plasma display devices, LED display devices such as mini LED and micro LED display elements, etc. The liquid crystal display device includes a liquid crystal display device using a wavelength conversion sheet.

[0067] The display device of the present disclosure may be electronic paper, and the electronic paper may include an electronic paper display element and the above-described barrier film of the present disclosure. The barrier film may be disposed so that the surface on the substrate side faces the electronic paper display element, or so that the surface on the overcoat layer side faces the electronic paper display element.

[0068] Fig. 3 is a cross-sectional view showing one embodiment of electronic paper 300 of the present disclosure. The electronic paper 300 of Fig. 3 includes an electronic paper display element 200 and a barrier film 100 of the present disclosure. The electronic paper 300 of Fig. 3 is arranged so that the surface of the barrier film 100 on the overcoat layer 14 side faces the electronic paper display element 200.

[0069] The electronic paper display element may be a general-purpose electronic paper display element, for example, an electronic paper display element having a rear electrode substrate having a rear substrate and a rear electrode, a transparent electrode substrate having a transparent substrate and a transparent electrode, and a display medium layer disposed between the rear electrode substrate and the transparent electrode substrate.

[0070] As the back electrode substrate, transparent electrode substrate and display medium layer, general-purpose back electrode substrate, transparent electrode substrate and display medium layer can be used. For example, the display medium layer can be appropriately selected depending on the display method of the electronic paper, such as electrophoresis, twist ball, powder migration, liquid crystal display, or electrochromic.

[0071] The electronic paper display element and the barrier film of the present disclosure are preferably laminated via an adhesive layer, and a general-purpose adhesive can be used as the adhesive constituting the adhesive layer.

[0072] The electronic paper of the present disclosure may have components other than the electronic paper display element and the barrier film of the present disclosure. Examples of components other than the electronic paper display element and the barrier film of the present disclosure include a touch panel, an anti-reflection film, and an anti-glare film. The touch panel is preferably disposed between the electronic paper display element and the barrier film of the present disclosure. The anti-reflection film and the anti-glare film are preferably disposed on the opposite side of the barrier film of the present disclosure from the electronic paper display element.

[0073] The display device of the present disclosure may be a liquid crystal display device, the liquid crystal display device including a backlight and a liquid crystal display element, the backlight including at least one light source that emits primary light, an optical plate that is disposed adjacent to the light source and that guides or diffuses light, and a wavelength conversion sheet that is disposed on the light emission side of the optical plate, and the wavelength conversion sheet includes the barrier film for a display device.

[0074] The liquid crystal display element and backlight may be general-purpose ones, and the light source and optical plate constituting the backlight may be general-purpose ones. An example of a wavelength conversion sheet constituting a backlight is one having a first protective film for quantum dots, a quantum dot-containing layer, and a second protective film for quantum dots in this order. In such a wavelength conversion sheet, at least one of the first protective film for quantum dots and the second protective film for quantum dots is preferably the barrier film for a display device of the present disclosure. In the wavelength conversion sheet, the barrier film is preferably arranged so that the surface on the overcoat layer side faces the quantum dot-containing layer side. The quantum dot-containing layer can be a general-purpose quantum dot-containing layer. Of the first protective film for quantum dots and the second protective film for quantum dots, the one that does not use the barrier film of the present disclosure can be a general-purpose protective film.

[0075] The present disclosure includes the following [1] to

[10] . [1] A substrate, an inorganic oxide layer, and an overcoat layer in this order; the inorganic oxide layer contains silicon oxide and has a thickness of 30 nm or more; The barrier film for a display device, wherein the overcoat layer contains an acrylic resin and has a thickness of more than 2.0 μm. [2] The barrier film for a display device according to [1], wherein the inorganic oxide layer and the overcoat layer are in contact with each other. [3] The barrier film for a display device further has a coating layer between the inorganic oxide layer and the overcoat layer, The barrier film for a display device according to [1], wherein the inorganic oxide layer and the coating layer are in contact with each other, and the coating layer and the overcoat layer are in contact with each other. [4] The barrier film for a display device further has an anchor coat layer between the substrate and the inorganic oxide layer, The barrier film for a display device according to any one of [1] to [3], wherein the substrate and the anchor coat layer are in contact with each other, and the anchor coat layer and the inorganic oxide layer are in contact with each other. [5] The barrier film for a display device according to any one of [1] to [4], wherein the inorganic oxide layer has a thickness of 40 nm or more and 200 nm or less. [6] The barrier film for a display device according to any one of [1] to [5], wherein the overcoat layer has a thickness of 2.5 μm or more and 40.0 μm or less. [7] The barrier film for a display device according to [3], wherein the thickness of the coating layer is 70 nm or more and 600 nm or less. [8] The barrier film for a display device has an L based on reflected light when the overcoat layer side is a light incident surface. * a * b * Color space b * The barrier film for a display device according to any one of [1] to [7], wherein the value is −1.0 or more and 5.0 or less. [9] A display device comprising the barrier film for a display device according to any one of [1] to [8].

[10] The display device according to [9], wherein the display device is electronic paper, and the electronic paper includes an electronic paper display element and the barrier film for the display device. [Example]

[0076] Next, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to these examples. "Parts" and "%" are based on mass unless otherwise specified.

[0077] 1. Measurement and Evaluation The following measurements and evaluations were carried out on the barrier films for display devices of the Examples and Comparative Examples. The results are shown in Table 1. The evaluations or measurements of 1-1 to 1-3 were carried out in an atmosphere at a temperature of 23°C ± 5°C and a relative humidity of 40% to 65%. Furthermore, before the evaluation or measurement, the samples were exposed to the above atmosphere for 30 minutes.

[0078] 1-1. 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 Research Laboratory, product number: HM-150). The light incident surface was the surface on the substrate side.

[0079] 1-2.b * value Samples were prepared by placing a perfectly diffusing standard white reflector on the substrate side of the barrier film of each of the examples and comparative examples. The surface of the sample on the overcoat layer side was used as the light incident surface, and the L based on the reflected light of the sample was measured. * a * b * Color space b * The measurement device used was a spectrophotometer manufactured by JASCO Corporation (product name: V670), and the following accessories were used: Accessory unit: Integrating sphere unit (JASCO Corporation, product number: ISN-723) Light source: Deuterium lamp (190~350nm), halogen lamp (330~2700nm) Measurement spot diameter: 2mm

[0080] 1-3.Ring-shaped rainbow pattern From the barrier films of the Examples and Comparative Examples, samples containing areas where black dots with a maximum diameter of 100 μm to 2000 μm were observed within the surface of the inorganic oxide layer were cut out. The black dots were confirmed using a magnifying glass with a scale in a bright room environment. The black plate and the sample were placed on top of each other on a horizontal table. The sample was placed on the black plate with the substrate side facing the black plate. The sample was visually evaluated for the presence of a ring-shaped rainbow pattern in a bright room environment where the illuminance on the sample surface was 500 lux or more and 1000 lux or less. Samples where no ring-shaped rainbow pattern was observed were rated "A," and samples where a ring-shaped rainbow pattern was observed were rated "C."

[0081] 1-4.Water vapor permeability (barrier properties) The water vapor permeability values ​​of the barrier films of the Examples and Comparative Examples were measured according to JIS K7129-2:2019. The measurement device used was a MOCON ultra-high sensitivity water vapor permeability measuring device (product name: AQUATRAN 3) manufactured by Hitachi High-Tech Science Corporation. The temperature and humidity conditions for measuring the water vapor permeability were 40°C and 90% relative humidity. Prior to measuring the water vapor permeability, the sample for measurement was exposed to an atmosphere with a temperature of 23°C ± 5°C and a relative humidity of 40% to 65% for 30 minutes. When the water vapor permeability was 0.020 g / m 2 A passing level is one that is less than 10 days.

[0082] 2. Preparation of barrier film for display devices [Example 1] Silicon oxide (SiO2) was deposited by vacuum deposition on one side of the substrate (biaxially oriented polyethylene terephthalate film, thickness: 25 μm, haze: 1%, total light transmittance: 91%) to form an inorganic oxide layer with a thickness of 50 nm. Next, the following coating solution for forming a coating layer was applied onto the inorganic oxide layer by gravure printing, and the coating layer was heat-treated at 180° C. for 60 seconds to form a coating layer having a thickness of 300 nm. Next, the following coating liquid for an overcoat layer was applied onto the coating layer by gravure printing, and the resulting mixture was heat-treated at 150°C for 10 seconds to form an overcoat layer with a thickness of 2.1 µm, thereby obtaining the barrier film for a display device of Example 1. The barrier film for a display device of Example 1 has, in this order, a substrate, an inorganic oxide layer, a coating layer, and an overcoat layer.

[0083] <Preparation of Coating Solution for Forming Coating Layer> Solution A was prepared by mixing tetraethoxysilane into a solution (pH 2.2) made by mixing water, isopropyl alcohol, and 0.5N hydrochloric acid while cooling the solution to 10°C. Separately, solution B was prepared by mixing polyvinyl alcohol with a saponification value of 99% or more and isopropyl alcohol. Solutions A and B were mixed to prepare a coating liquid for forming a coating layer (solid content: 5% by mass). In the coating liquid for forming a coating layer, the mass ratio of tetraethoxysilane to polyvinyl alcohol was 29:4.

[0084] <Coating liquid for overcoat layer> An acrylic resin (manufactured by DIC Corporation, trade name: ACRYDIC A-166) was diluted with a solvent to a solid content of 10% by mass to prepare a coating liquid for the overcoat layer.

[0085] [Examples 2 to 5] Barrier films for displays of Examples 2 to 5 were obtained in the same manner as in Example 1, except that the thickness of the inorganic oxide layer and the thickness of the overcoat layer were set to the values ​​shown in Table 1.

[0086] [Comparative Example 1] A barrier film for a display device of Comparative Example 1 was obtained in the same manner as in Example 1, except that no overcoat layer was provided on the coating layer.

[0087] Comparative Example 2 A barrier film for a display device of Comparative Example 2 was obtained in the same manner as in Example 1, except that the thickness of the overcoat layer was changed to 0.8 μm.

[0088] Comparative Example 3 A barrier film for a display device of Comparative Example 3 was obtained in the same manner as in Example 1, except that the thickness of the inorganic oxide layer was changed to 25 nm.

[0089] Comparative Example 4 A barrier film for a display device of Comparative Example 4 was obtained in the same manner as in Example 1, except that the inorganic oxide layer was changed to an inorganic oxide layer having a thickness of 10 nm, on which aluminum oxide was vapor-deposited by a vacuum vapor deposition method.

[0090] [Table 1]

[0091] The results in Table 1 confirm that the barrier films for display devices of the Examples have good barrier properties due to their low water vapor permeability. Furthermore, the results in Table 1 confirm that the barrier films for display devices of the Examples do not show any ring-shaped rainbow pattern, which means that they can suppress deterioration in display quality. [Explanation of symbols]

[0092] 11: Base material 12: Inorganic oxide layer 13: Covering layer 14: Overcoat layer 100: Barrier film for display devices 200: Electronic paper display element 300: Electronic paper

Claims

1. The film has a substrate, an inorganic oxide layer, and an overcoat layer in this order, the inorganic oxide layer contains silicon oxide and has a thickness of 30 nm or more; The barrier film for a display device, wherein the overcoat layer contains an acrylic resin and has a thickness of more than 2.0 μm.

2. The barrier film for a display device according to claim 1 , wherein the inorganic oxide layer and the overcoat layer are in contact with each other.

3. the barrier film for a display device further has a coating layer between the inorganic oxide layer and the overcoat layer, The barrier film for a display device according to claim 1 , wherein the inorganic oxide layer and the coating layer are in contact with each other, and the coating layer and the overcoat layer are in contact with each other.

4. The barrier film for a display device further has an anchor coat layer between the substrate and the inorganic oxide layer, The barrier film for a display device according to claim 1 , wherein the substrate and the anchor coat layer are in contact with each other, and the anchor coat layer and the inorganic oxide layer are in contact with each other.

5. 2. The barrier film for a display device according to claim 1, wherein the inorganic oxide layer has a thickness of 40 nm or more and 200 nm or less.

6. 2. The barrier film for a display device according to claim 1, wherein the overcoat layer has a thickness of 2.5 μm or more and 40.0 μm or less.

7. The barrier film for a display device according to claim 3, wherein the thickness of the coating layer is 70 nm or more and 600 nm or less.

8. The barrier film for a display device has an L based on reflected light when the overcoat layer side is a light incident surface. ＊ a ＊ b ＊ Color system b ＊ 2. The barrier film for a display device according to claim 1, wherein the value is −1.0 or more and 5.0 or less.

9. A display device comprising the barrier film for a display device according to any one of claims 1 to 8.

10. the display device is electronic paper, The display device according to claim 9 , wherein the electronic paper includes an electronic paper display element and the barrier film for the display device.

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