Multilayer structure and method for producing same, protective sheet for electronic device using said multilayer structure, and electronic device

Abstract

Provided are: a multilayer structure having high barrier properties and clarity and a method for producing the same; a protective sheet for an electronic device using the multilayer structure; and an electronic device. This multilayer structure includes a substrate (X) and a layer (Y). The layer (Y) contains a reaction product (D) of a metal oxide (A) that includes aluminum atoms, and an inorganic phosphorous compound (BI). The substrate (X) and the layer (Y) are contiguous. The image clarity of the multilayer structure with an optical comb width of 0.25 mm when measured according to ISO17221:2014 is 90% or more.

Description

Multilayer structure, method for producing the same, and protective sheet for electronic device and electronic device using the same

[0001] The present invention relates to a multilayer structure having high gas barrier properties and water vapor barrier properties and high clarity, a method for producing the same, and a protective sheet for an electronic device and an electronic device using the same.

[0002] Electronic devices such as solar cells and electronic devices equipped with display devices require a light-transmitting protective member to protect their surfaces. Examples of such protective members include thick glass plates and protective sheets having excellent barrier properties (oxygen barrier properties and water vapor barrier properties) and comprising a barrier layer on a resin substrate.

[0003] As an example of a protective sheet with excellent barrier properties, Patent Document 1 describes an electronic device equipped with a protective sheet containing a multilayer structure in which a coating liquid containing an aluminum-containing compound and a phosphorus compound is applied to a substrate (X), followed by drying and heat treatment to provide a layer (Y) containing a reaction product, the reaction product having an average particle size of 5 to 70 nm. The document also describes that such a protective sheet has excellent gas barrier properties and water vapor barrier properties, and is able to maintain these properties even after a dump heat test.

[0004] International Publication No. 2016 / 103720

[0005] In recent years, protective sheets (multilayer structures) for electronic devices and the like are sometimes required to have a higher level of clarity, and the multilayer structures used in the conventional electronic devices may not have sufficient clarity. The high barrier properties of the multilayer structures used in the conventional electronic devices make them useful as protective sheets for electronic devices and the like, and a multilayer structure having high clarity while maintaining such performance is desired. In order to realize a multilayer structure with high clarity, the present inventors have conducted repeated studies using a substrate with high image clarity as the substrate (X), but have found it difficult to achieve high clarity. As a result of extensive studies, the present inventors have found that there is a relationship between the coating speed of the coating liquid applied when forming the layer (Y) and the clarity of the resulting multilayer structure, leading to the realization of the present invention.

[0006] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a multilayer structure having high barrier properties and clarity, a method for producing the same, and a protective sheet for an electronic device and an electronic device using the same.

[0007] According to the present invention, the object is to provide a multilayer structure having: [1] a multilayer structure including a substrate (X) and a layer (Y), wherein the layer (Y) contains a reaction product (D) of a metal oxide (A) containing aluminum atoms (hereinafter, may be abbreviated simply as "metal oxide (A)") and an inorganic phosphorus compound (BI), the substrate (X) and the layer (Y) being adjacent to each other; and wherein the multilayer structure has an image clarity of 90% or more at an optical comb width of 0.25 mm measured in accordance with ISO 17221:2014; [2] the multilayer structure of [1], wherein the haze value measured in accordance with JIS K7105:1981 is 3% or less; [3] the multilayer structure having a water vapor transmission rate of 1×10 at 40° C. and 90% RH measured in accordance with ISO 15106-5:2015 －２ g / m ２[4] The multilayer structure of any of [1] to [3], wherein the heat shrinkage rate in the MD direction of the substrate (X) when heated at 210°C for 1 minute is 2.90% or less; [5] The multilayer structure of any of [1] to [4], wherein the image clarity of the substrate (X) at an optical comb width of 0.25 mm, measured in accordance with ISO17221:2014, is 90% or more; [6] The multilayer structure of any of [1] to [5], wherein the substrate (X) has a surface layer; [7] The multilayer structure of any of [1] to [6], wherein the substrate (X) and the layer (Y) are directly laminated together; [8] The multilayer structure of any of [1] to [6], wherein the substrate (X) and the layer (Y) are laminated together via an adhesive layer (I); [9] The multilayer structure of [1] to [8], wherein the layer (Y) is disposed on each of both surfaces of the substrate (X);

[10] A method for producing a multilayer structure, comprising: a step (I) of applying a coating liquid (S) containing a metal oxide (A) containing aluminum atoms, an inorganic phosphorus compound (BI), and a solvent to at least one surface of a substrate (X), and removing the solvent to form a precursor layer of layer (Y); and a step (II) of heat-treating the precursor layer of layer (Y) to form layer (Y), wherein the coating speed of the coating liquid (S) in step (I) is 0.03 cm / s or more and 2.5 cm / s or less per cm of coating width, and the image clarity of the resulting multilayer structure at an optical comb width of 0.25 mm, as measured in accordance with ISO 17221:2014, is 90% or more;

[11] A protective sheet for an electronic device, comprising the multilayer structure of any of [1] to [9];

[12] The protective sheet of

[11] , which is a protective sheet for protecting the surface of a photoelectric conversion device, an information display device, or a lighting device;

[13] An electronic device having the protective sheet of

[11] or

[12] .

[0008] According to the present invention, it is possible to provide a multilayer structure having high barrier properties and clarity, a method for producing the same, and a protective sheet for an electronic device and an electronic device using the same.

[0009] In this specification, "barrier properties" mainly refers to both oxygen barrier properties and water vapor barrier properties, and "gas barrier properties" mainly refers to oxygen barrier properties. Furthermore, "clarity" is an evaluation of the clarity of an image seen through the multilayer structure of the present invention, and is determined by the visibility of an image seen through the multilayer structure of the present invention when visually confirmed, as described in the Examples.

[0010] [Multilayer structure] The multilayer structure of the present invention is a multilayer structure including a substrate (X) and a layer (Y), wherein the layer (Y) contains a reaction product (D) of a metal oxide (A) and an inorganic phosphorus compound (BI), the substrate (X) and the layer (Y) are adjacent to each other, and the image clarity of the multilayer structure is 90% or more at an optical comb width of 0.25 mm, as measured in accordance with ISO 17221:2014.

[0011] In this specification, "adjacent" means that they are stacked in a very close state, specifically, directly or via another layer such as an adhesive layer (for example, an adhesive layer having a thickness of 10 μm or less). In a configuration in which the substrate (X) and the layer (Y) are adjacent to each other, the distance between the substrate (X) and the layer (Y) may be 0 μm or more and 10 μm or less, 0 μm or more and 1 μm or less, 0 μm or more and 0.1 μm or less, or 0 μm or more and 0.03 μm or less. Furthermore, for example, when there are multiple substrates (X), it is sufficient that one of the substrates (X) is adjacent to the layer (Y), and the other substrates (X) may or may not be adjacent to the layer (Y). Similarly, when there are multiple layers (Y), it is sufficient that one of the layers (Y) is adjacent to the substrate (X), and the other layers (Y) may or may not be adjacent to the substrate (X). In other words, it is sufficient that at least one pair of the substrate (X) and the layer (Y) is adjacent to each other.

[0012] The multilayer structure of the present invention has an image clarity of 90% or more, and therefore has excellent sharpness when used, for example, as a protective sheet for an electronic device. The image clarity of the multilayer structure of the present invention is preferably 91% or more, more preferably 92% or more, even more preferably 93% or more, and in some cases even more preferably 94% or more or 95% or more. The image clarity of the multilayer structure of the present invention may be 100% or less, or may be 99%, 98%, 97%, or 96% or less.

[0013] Although the details of the method for achieving an image clarity of 90% or more in the multilayer structure of the present invention will be described later, it is particularly important to use a substrate (X) with high image clarity and to apply the coating liquid (S) described below at a coating speed of 0.03 cm / s to 2.5 cm / s per cm of coating width. Here, "0.03 cm / s to 2.5 cm / s per cm of coating width" means that the coating speed conditions change depending on the length of the coating width. For example, when the coating width is 10 cm (when coating is performed over a 10 cm width), this means that the coating speed is 0.3 cm / s to 25 cm / s. When coating is performed on the entire surface of one side of the substrate (X) in a direction perpendicular to the width of the substrate (X) at one time, the coating width is equal to the width of the substrate (X). Note that, depending on the smoothness of the layer (Y) provided by coating or the like, the image clarity of the multilayer structure may be higher than that of the substrate (X).

[0014] In this specification, the term "thickness" refers to the average value (average thickness) of measurements taken at any five points.

[0015] [Substrate (X)] The material of the substrate (X) is not particularly limited, but preferably contains a thermoplastic resin from the viewpoint of high image clarity. The form of the substrate (X) is not particularly limited, but it is preferably in the form of a layer such as a film or a sheet. The substrate (X) preferably contains a thermoplastic resin film or a thermoplastic resin film laminated with an inorganic vapor deposition layer (X'), more preferably contains a thermoplastic resin film, and even more preferably is a thermoplastic resin film.

[0016] Examples of thermoplastic resins used in the substrate (X) include polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate (PET), polyethylene-2,6-naphthalate, polybutylene terephthalate, and copolymers thereof; polyamide resins such as nylon-6, nylon-66, and nylon-12; hydroxyl group-containing polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers; polystyrene; poly(meth)acrylic acid esters; polyacrylonitrile; polyvinyl acetate; polycarbonate; polyarylate; regenerated cellulose; polyimide; polyetherimide; polysulfone; polyethersulfone; polyetheretherketone; ionomer resins, etc. The thermoplastic resin used in the substrate (X) is preferably at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, nylon-6, and nylon-66, and more preferably polyethylene terephthalate from the viewpoint of excellent image clarity.

[0017] The substrate (X) may contain inorganic or organic fine particles to impart easy sliding properties and blocking resistance. From the viewpoint of improving the image clarity of the substrate (X), when inorganic or organic fine particles are contained, they are preferably contained in a surface layer described below. That is, from the viewpoint of image clarity, it may be preferable that the portion of the substrate (X) other than the surface layer does not contain inorganic or organic fine particles. Examples of inorganic fine particles that can be used include metals such as gold, silver, copper, platinum, palladium, rhenium, vanadium, osmium, cobalt, iron, zinc, ruthenium, praseodymium, chromium, nickel, aluminum, tin, zinc, titanium, tantalum, zirconium, antimony, indium, yttrium, and lanthanum, metal oxides such as zinc oxide, titanium oxide, cesium oxide, antimony oxide, tin oxide, indium-tin oxide, yttrium oxide, lanthanum oxide, zirconium oxide, aluminum oxide, and silicon oxide, metal fluorides such as lithium fluoride, magnesium fluoride, aluminum fluoride, and cryolite, metal phosphates such as calcium phosphate, carbonates such as calcium carbonate, sulfates such as barium sulfate, and talc and kaolin. Examples of organic fine particles that can be used include crosslinked fine particles such as silicone compounds, crosslinked styrenes, crosslinked acrylics, and crosslinked melamines, as well as thermoplastic resins that are incompatible with the thermoplastic resin constituting the substrate (X) but that form a sea-island structure when finely dispersed. The average particle size of the fine particles (inorganic and organic fine particles) used is preferably 0.001 to 5 μm.

[0018] When the thermoplastic resin film is used as the substrate (X), the substrate (X) may be a stretched film or a non-stretched film. A stretched film, particularly a biaxially stretched film, is preferred because the resulting multilayer structure has excellent processability (printing, lamination, etc.). The biaxially stretched film may be a biaxially stretched film produced by any of simultaneous biaxial stretching, sequential biaxial stretching, and tubular stretching.

[0019] The thickness of each layer of the substrate (X) is preferably 5 μm or more and 200 μm or less, more preferably 7 μm or more and 150 μm or less, and even more preferably 10 μm or more and 100 μm or less. When the thickness of each layer of the substrate (X) is 5 μm or more, the mechanical strength and processability tend to be excellent. Furthermore, when the thickness of each layer of the substrate (X) is 200 μm or less, the flexibility of the resulting multilayer structure tends to be excellent.

[0020] The substrate (X) preferably has high image clarity. The image clarity of the substrate (X) at an optical comb width of 0.25 mm, measured in accordance with ISO 17221:2014, is preferably 90% or more, more preferably 91% or more, and even more preferably 92% or more. From the viewpoint of production costs, the image clarity of the substrate (X) may be 99% or less, 97% or less, 96% or less, or 95% or less. When the image clarity of the substrate (X) is 90% or more, it is easy to adjust the image clarity of the obtained multilayer structure to 90% or more.

[0021] Examples of means for adjusting the image clarity of the substrate (X) to 90% or more include not containing any additives (components other than thermoplastic resins) in layers other than the surface layer described below, or containing only a small amount of additives, if any, and providing a surface layer described below.

[0022] The substrate (X) preferably has a surface layer from the viewpoint of imparting various functions and improving the image clarity of the substrate (X). The surface layer is a layer provided on the surface of the substrate (X) and may be provided on one or both sides of the substrate (X). The substrate (X) may have a resin substrate layer and a surface layer laminated on one or both sides of the resin substrate layer. The resin substrate layer may be a layer of the thermoplastic resin described above as the thermoplastic resin used in the substrate (X). The resin substrate layer may be a PET layer. Another layer such as an inorganic vapor deposition layer (X') may be present between the resin substrate layer and the surface layer. It is preferable that the resin substrate layer and the surface layer are directly laminated. Even when the surface layer is mainly composed of a resin, the resin substrate layer and the surface layer can be distinguished by differences in the composition of each layer.

[0023] The surface layer is not particularly limited as long as it has adhesiveness to the resin substrate layer, etc., but preferably contains a thermoplastic resin as its main component. Here, "mainly containing" means that the content is greater than 50% by mass. Suitable examples of the thermoplastic resin include polyester-based resins, polycarbonate-based resins, epoxy-based resins, alkyd-based resins, acrylic-based resins, urea-based resins, and urethane-based resins. Two or more different thermoplastic resins may also be used in combination, such as a polyester-based resin and a urethane-based resin, a polyester-based resin and an acrylic-based resin, or a urethane-based resin and an acrylic-based resin. Among these, at least one selected from the group consisting of polyester-based resins, acrylic resins, and urethane-based resins is preferred, with polyester-based resins being more preferred.

[0024] It may be preferable for the surface layer to contain various crosslinking agents, from the viewpoint of improving heat-resistant adhesion and dramatically improving moisture-resistant adhesion at the same time. In particular, when a polyester resin, urethane resin, or acrylic resin is used as the main component of the surface layer and a crosslinkable functional group is copolymerized with the resin, it is preferable for the surface layer to further contain a crosslinking agent. The thermoplastic resin and crosslinking agent constituting the surface layer can be mixed in any ratio, but from the viewpoint of improving adhesion, the crosslinking agent is preferably 0.2 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the thermoplastic resin.

[0025] The surface layer may contain the inorganic or organic fine particles described above in order to impart lubricity and anti-blocking properties.

[0026] The heat shrinkage rate of the substrate (X) in the MD direction when heated at 210°C for 1 minute is preferably 2.90% or less, and more preferably 2.80% or less, from the viewpoint of further improving the water vapor barrier property and image clarity. The heat shrinkage rate of the substrate (X) in the MD direction may be 0.5% or more, but from the viewpoint of further improving the water vapor barrier property, 2.10% or more may be preferred. This heat shrinkage rate of the substrate (X) may be the heat shrinkage rate of the substrate (X) used as a raw material for the multilayer structure (substrate (X) before the formation of layer (Y) described below).

[0027] Commercially available products can be used as the substrate (X). Examples of commercially available products with high image clarity include Lumirror (registered trademark) U403, U483, A48, and XW731C manufactured by Toray Industries, Inc., RH210 manufactured by Hyosung Co., Ltd., Diafoil (registered trademark) T600 manufactured by Mitsubishi Chemical Corporation, Cosmoshine (registered trademark) A4160, SRF, and Toyobo Ester (registered trademark) Film HPE manufactured by Toyobo Co., Ltd. These have a surface layer on both sides or one side.

[0028] The substrate (X) is preferably surface-treated from the viewpoint of coatability with the coating liquid (S) described below and the barrier properties of the resulting multilayer structure. The surface treatment can be carried out by a known method, such as UV ozone treatment, high-concentration ozone water treatment, excimer ozone treatment, corona treatment, oxygen plasma treatment, or AP plasma treatment.

[0029] The thermoplastic resin film laminated with an inorganic vapor deposition layer (X') used as the substrate (X) typically has barrier properties against oxygen and water vapor and is a transparent film. When a thermoplastic resin film having an inorganic vapor deposition layer (X') laminated on one side is used as the substrate (X), the layer (Y) described below is laminated on the inorganic vapor deposition layer (X') side. The thermoplastic resin film used in the thermoplastic resin film laminated with an inorganic vapor deposition layer (X') can be any of the thermoplastic resin films exemplified as the substrate (X). The inorganic vapor deposition layer (X') can be formed by vapor deposition of an inorganic substance. Examples of inorganic substances include metal oxides (e.g., silicon oxide, aluminum oxide), metal nitrides (e.g., silicon nitride), and metal nitride oxides (e.g., silicon oxynitride). Among these, an inorganic vapor deposition layer (X') formed of aluminum oxide, silicon oxide, magnesium oxide, or silicon nitride is preferred from the viewpoint of excellent transparency. In some cases, it is preferable that the substrate (X) does not include an inorganic vapor deposition layer (X') from the viewpoint of image clarity.

[0030] The method for forming the inorganic vapor deposition layer (X′) is not particularly limited, and examples thereof include physical vapor deposition methods such as vacuum deposition (e.g., resistance heating deposition, electron beam deposition, molecular beam epitaxy, etc.), sputtering, and ion plating; and chemical vapor deposition methods such as thermal chemical vapor deposition (e.g., catalytic chemical vapor deposition), photochemical vapor deposition, plasma chemical vapor deposition (e.g., capacitively coupled plasma, inductively coupled plasma, surface wave plasma, electron cyclotron resonance, dual magnetron, atomic layer deposition, etc.), and metalorganic chemical vapor deposition.

[0031] The thickness of the inorganic vapor deposition layer (X') varies depending on the types of components constituting the inorganic vapor deposition layer, but is preferably 0.002 to 0.5 μm, more preferably 0.005 to 0.2 μm, and even more preferably 0.01 to 0.1 μm. A thickness within this range may be selected so that the barrier properties and mechanical properties of the multilayer structure are improved. When the thickness of the inorganic vapor deposition layer (X') is 0.002 μm or more, the barrier properties of the inorganic vapor deposition layer (X') against oxygen and water vapor tend to be improved. Furthermore, when the thickness of the inorganic vapor deposition layer (X') is 0.5 μm or less, the barrier properties of the inorganic vapor deposition layer (X') tend to be maintained even after bending.

[0032] As the substrate (X), one type of substrate may be used alone, or two or more types of substrates may be used in combination. When the substrate (X) has multiple layers, the substrates (X) may be the same or different. The number of layers of the substrate (X) may be one layer or two or more layers. The number of layers of the substrate (X) is, for example, one layer or more and three layers or less, preferably one layer or more and two layers or less, and more preferably one layer.

[0033] [Layer (Y)] The layer (Y) contains a reaction product (D) of a metal oxide (A) and an inorganic phosphorus compound (BI). In the multilayer structure of the present invention, the layer (Y) functions as a barrier layer, and therefore, the multilayer structure of the present invention tends to have good barrier properties when it includes the layer (Y). Furthermore, by forming the layer (Y) by an appropriate method, the image clarity of the multilayer structure can be made 90% or more.

[0034] (Metal Oxide (A) Containing Aluminum Atoms) The metal atoms constituting the metal oxide (A) (sometimes collectively referred to as "metal atoms (M)") are usually at least one metal atom selected from metal atoms belonging to Groups 2 to 14 of the periodic table, and contain at least an aluminum atom. The metal atom (M) is preferably an aluminum atom alone, but may contain an aluminum atom and another metal atom. Two or more metal oxides (A) may be mixed and used as the metal oxide (A). Examples of metal atoms other than aluminum atoms include metals in Group 2 of the periodic table, such as magnesium and calcium; metals in Group 12 of the periodic table, such as zinc; metals in Group 13 of the periodic table; metals in Group 14 of the periodic table, such as silicon; and transition metals, such as titanium and zirconium. While silicon is sometimes classified as a metalloid, silicon is considered to be included in the metals herein. The metal atom (M) that can be used in combination with aluminum is preferably at least one selected from the group consisting of titanium and zirconium, from the viewpoints of ease of handling and excellent gas barrier properties of the resulting multilayer structure.

[0035] The proportion of aluminum atoms in the metal atoms (M) is preferably 50 mol % or more, more preferably 70 mol % or more, and even more preferably 90 mol % or more, and even if it is 95 mol % or more, it may be composed essentially of aluminum atoms. Examples of the metal oxide (A) include metal oxides produced by methods such as liquid phase synthesis, vapor phase synthesis, and solid pulverization.

[0036] (Compound (E) containing a metal atom (M) having a hydrolyzable characteristic group bonded thereto) The metal oxide (A) may be a hydrolysis condensate of a compound (E) (hereinafter sometimes abbreviated as "compound (E)") containing a metal atom (M) having a hydrolyzable characteristic group bonded thereto. Examples of the characteristic group include a halogen atom, NO ３Examples of the metal oxide (E) include an alkoxy group having 1 to 9 carbon atoms which may have a substituent, an aryloxy group having 6 to 9 carbon atoms which may have a substituent, an acyloxy group having 2 to 9 carbon atoms which may have a substituent, an alkenyloxy group having 3 to 9 carbon atoms which may have a substituent, a β-diketonato group having 5 to 15 carbon atoms which may have a substituent, and a diacylmethyl group having an acyl group having 1 to 9 carbon atoms which may have a substituent. The hydrolysis condensate of compound (E) can be considered to be substantially the metal oxide (A). Therefore, in this specification, the hydrolysis condensate of compound (E) may be referred to as "metal oxide (A)." That is, in this specification, "metal oxide (A)" can be read as "hydrolysis condensate of compound (E)," and "hydrolysis condensate of compound (E)" can also be read as "metal oxide (A)."

[0037] The compound (E) preferably contains a compound (Ea) containing an aluminum atom, which will be described later, because this makes it easier to control the reaction with the inorganic phosphorus compound (BI) and the resulting multilayer structure has excellent gas barrier properties.

[0038] Examples of the compound (Ea) include aluminum chloride, aluminum nitrate, aluminum acetate, tris(2,4-pentanedionato)aluminum, trimethoxyaluminum, triethoxyaluminum, tri-n-propoxyaluminum, triisopropoxyaluminum, tri-n-butoxyaluminum, tri-sec-butoxyaluminum, tri-tert-butoxyaluminum, etc., and among these, triisopropoxyaluminum and tri-sec-butoxyaluminum are preferred. Two or more types of the compound (Ea) may be used in combination as the compound (E).

[0039] Furthermore, the compound (E) may contain a compound (Eb) containing a metal atom (M) other than aluminum. Examples of the compound (Eb) include titanium compounds such as tetrakis(2,4-pentanedionato)titanium, tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-butoxytitanium, and tetrakis(2-ethylhexoxy)titanium; and zirconium compounds such as tetrakis(2,4-pentanedionato)zirconium, tetra-n-propoxyzirconium, and tetra-n-butoxyzirconium. These compounds (Eb) may be used alone or in combination of two or more.

[0040] The proportion of compound (Ea) in compound (E) is not particularly limited, and is, for example, preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and may be 100 mol%.

[0041] By hydrolyzing compound (E), at least a portion of the hydrolyzable characteristic groups of compound (E) is converted to hydroxyl groups. Furthermore, the hydrolyzate is condensed to form a compound in which a metal atom (M) is bonded via an oxygen atom (O). When this condensation is repeated, a compound that can be essentially considered a metal oxide is formed. Note that hydroxyl groups are usually present on the surface of the metal oxide (A) formed in this manner.

[0042] In this specification, compounds in which the ratio of [the number of moles of oxygen atoms (O) bonded only to metal atoms (M)] / [the number of moles of metal atoms (M)] is 0.8 or more are considered to be included in the metal oxide (A). Here, the oxygen atom (O) bonded only to the metal atom (M) is the oxygen atom (O) in a structure represented by M-O-M, and excludes oxygen atoms bonded to the metal atom (M) and a hydrogen atom (H), such as the oxygen atom (O) in a structure represented by M-O-H. The ratio in the metal oxide (A) is preferably 0.9 or more, more preferably 1.0 or more, and even more preferably 1.1 or more. There are no particular limitations on the upper limit of this ratio, but it is usually expressed as n / 2, where n is the valence of the metal atom (M).

[0043] For the hydrolysis and condensation to occur, it is important that compound (E) has a hydrolyzable characteristic group. If such a group is not bonded, the hydrolysis and condensation reaction does not occur or occurs very slowly, making it difficult to prepare the target metal oxide (A).

[0044] The hydrolysis condensate of compound (E) may be produced from a specific raw material by, for example, a method employed in a known sol-gel process. The raw material may be at least one selected from the group consisting of compound (E), a partial hydrolysis product of compound (E), a complete hydrolysis product of compound (E), a compound obtained by partial hydrolysis condensation of compound (E), and a compound obtained by partial condensation of a complete hydrolysis product of compound (E).

[0045] It is preferable that the metal oxide (A) to be mixed with the inorganic phosphorus compound (BI)-containing material (the inorganic phosphorus compound (BI) or a composition containing the inorganic phosphorus compound (BI)) described below does not substantially contain phosphorus atoms.

[0046] (Inorganic phosphorus compound (BI)) The inorganic phosphorus compound (BI) contains a site capable of reacting with the metal oxide (A), and typically contains a plurality of such sites, preferably 2 to 20 sites. Such sites include sites capable of condensation reaction with functional groups (e.g., hydroxyl groups) present on the surface of the metal oxide (A), and examples thereof include halogen atoms directly bonded to phosphorus atoms and oxygen atoms directly bonded to phosphorus atoms. The functional groups (e.g., hydroxyl groups) present on the surface of the metal oxide (A) are usually bonded to metal atoms (M) constituting the metal oxide (A).

[0047] Examples of the inorganic phosphorus compound (BI) include phosphorus oxoacids such as phosphoric acid, diphosphoric acid, triphosphoric acid, polyphosphoric acid in which four or more molecules of phosphoric acid are condensed, phosphorous acid, phosphonic acid, phosphonous acid, phosphinic acid, and phosphinous acid, as well as salts thereof (e.g., sodium phosphate), and derivatives thereof (e.g., halides (e.g., phosphoryl chloride), dehydrates (e.g., diphosphorus pentoxide)). The inorganic phosphorus compound (BI) may be used alone or in combination with two or more. Among these, from the viewpoint of improving the stability of the coating liquid (S) described below and the gas barrier properties of the resulting multilayer structure, it is preferable to use phosphoric acid alone or to use phosphoric acid in combination with another inorganic phosphorus compound. When phosphoric acid is used in combination with another inorganic phosphorus compound, it is preferable that 50 mol % or more of the inorganic phosphorus compound (BI) is phosphoric acid.

[0048] (Reaction Product (D)) The reaction product (D) is obtained by the reaction of the metal oxide (A) with the inorganic phosphorus compound (BI). Compounds produced by the reaction of the metal oxide (A), the inorganic phosphorus compound (BI), and other compounds are also included in the reaction product (D).

[0049] In the infrared absorption spectrum of layer (Y), －１ The maximum absorption wavenumber in the region is 1080-1130 cm －１ For example, in the process of reacting a metal oxide (A) with an inorganic phosphorus compound (BI) to form a reaction product (D), a metal atom (M) derived from the metal oxide (A) and a phosphorus atom (P) derived from the inorganic phosphorus compound (BI) form a bond represented by M-O-P via an oxygen atom (O). As a result, a characteristic absorption band derived from this bond appears in the infrared absorption spectrum of the reaction product (D). The characteristic absorption band based on the M-O-P bond is in the range of 1080 to 1130 cm －１ In particular, when the characteristic absorption band is in the region of 800 to 1400 cm where absorption due to bonding of various atoms with oxygen atoms is generally observed, the resulting multilayer structure exhibits excellent gas barrier properties. －１ When the absorption is strongest in the region of , the resulting multilayer structure exhibits even better gas barrier properties.

[0050] In contrast, when a metal compound such as compound (E) or a metal salt and an inorganic phosphorus compound (BI) are mixed in advance and then hydrolyzed and condensed, a complex is obtained in which metal atoms derived from the metal compound and phosphorus atoms derived from the inorganic phosphorus compound (BI) are mixed and reacted almost uniformly. In this case, in the infrared absorption spectrum, －１ The maximum absorption wavenumber in the region is 1080 to 1130 cm －１ It will be out of range.

[0051] In the infrared absorption spectrum of layer (Y), －１ The half width of the maximum absorption band in the region is 200 cm from the viewpoint of the gas barrier property of the resulting multilayer structure. －１ Preferably less than 150 cm －１ Less than 100 cm is more preferable. －１ More preferably, 50 cm or less －１ The following are particularly preferred:

[0052] The infrared absorption spectrum of the layer (Y) was measured using a Fourier transform infrared spectrophotometer (Spectrum One manufactured by PerkinElmer Co., Ltd.) in the range of 800 to 1400 cm －１ However, when the measurement cannot be performed by the above-mentioned method, a reflection measurement such as a reflection absorption method, an external reflection method, or an attenuated total reflection method, or a transmission measurement method such as a Nujol method or a tablet method after scraping off the layer (Y) from the multilayer structure may be performed, but the method is not limited to these.

[0053] Furthermore, the layer (Y) may partially contain the metal oxide (A) and / or the inorganic phosphorus compound (BI) that are not involved in the reaction.

[0054] In the layer (Y), the molar ratio of metal atoms derived from the metal oxide (A) to phosphorus atoms derived from the inorganic phosphorus compound (BI) is preferably in the range of [metal atoms derived from the metal oxide (A)]:[phosphorus atoms derived from the inorganic phosphorus compound (BI)]=1.0:1.0 to 3.6:1.0, more preferably 1.1:1.0 to 3.0:1.0. Excellent gas barrier performance can be obtained within this range. The molar ratio in the layer (Y) can be adjusted by the mixing ratio of the metal oxide (A) to the inorganic phosphorus compound (BI) in the coating liquid (S) used to form the layer (Y). The molar ratio in the layer (Y) is usually the same as the ratio in the coating liquid (S).

[0055] The thickness of the layer (Y) (when the multilayer structure has two or more layers (Y), the total thickness of the layers (Y)) is preferably 0.05 to 4.0 μm, more preferably 0.1 to 2.0 μm. By making the layer (Y) thin, dimensional changes in the multilayer structure during processing such as printing and lamination can be suppressed. Furthermore, since the flexibility of the multilayer structure is increased, its mechanical properties can be made closer to those of the substrate itself. From the viewpoint of gas barrier properties, the thickness of each layer (Y) is preferably 0.05 μm or more, more preferably 0.1 μm or more. The thickness of each layer (Y) is preferably 2.0 μm or less, more preferably 1.0 μm or less. The thickness of the layer (Y) can be controlled by the concentration of the coating liquid (S) described below used to form the layer (Y) or its application method. The thickness of the layer (Y) can be measured by observing the cross section of the multilayer structure with a scanning electron microscope or a transmission electron microscope.

[0056] The number of layers (Y) may be one or two or more. By having two or more layers (Y), the barrier property tends to be improved. The number of layers (Y) may be two. When two or more layers (Y) are present, it is preferable that a layer (Y) is disposed on each of both surfaces of each substrate (X). When two or more layers (Y) are present, the lamination method is not particularly limited, and the layer (Y) may be disposed directly on one or both surfaces of the substrate (X), or a multilayer structure including the layer (Y) may be bonded using an adhesive layer (I) described below.

[0057] The layer (Y) may further contain other components in addition to the above-mentioned components (metal oxide (A), inorganic phosphorus compound (BI), and their reaction product (D)). Examples of other components that can be contained in the layer (Y) include a polymer (F) (hereinafter sometimes abbreviated as "polymer (F)") having at least one functional group selected from the group consisting of a carbonyl group, a hydroxyl group, a carboxyl group, a carboxylic anhydride group, and a salt of a carboxyl group, an organic phosphorus compound (BO), a crosslinking agent-containing resin composition (V), inorganic acid metal salts such as carbonates, hydrochlorides, nitrates, bicarbonates, sulfates, hydrogen sulfates, and borates, organic acid metal salts such as oxalates, acetates, tartrates, and stearates, metal complexes such as cyclopentadienyl metal complexes (e.g., titanocene) and cyanometal complexes (e.g., Prussian blue), layered clay compounds, crosslinking agents, polymer compounds other than the polymer (F), plasticizers, antioxidants, ultraviolet absorbers, and flame retardants. The content of the other components in layer (Y) in the multilayer structure is preferably 50% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and may be 4% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, or 0% by mass (no other components included). From the viewpoint of having higher clarity in the multilayer structure of the present invention, it is preferable that the content of other components is low.

[0058] (Polymer (F)) The polymer (F) has at least one functional group selected from the group consisting of a carbonyl group, a hydroxyl group, a carboxyl group, a carboxylic anhydride group, and a salt of a carboxyl group. The polymer (F) is preferably a polymer having at least one functional group selected from the group consisting of a hydroxyl group and a carboxyl group.

[0059] Examples of the polymer (F) include polyethylene glycol; polyvinyl alcohol-based polymers such as polyvinyl alcohol, modified polyvinyl alcohol containing 1 to 50 mol% of α-olefin units having 4 or less carbon atoms, and polyvinyl acetal (e.g., polyvinyl butyral); polysaccharides such as cellulose and starch; (meth)acrylic acid-based polymers such as polyhydroxyethyl (meth)acrylate, poly(meth)acrylic acid, and ethylene-acrylic acid copolymer; and maleic acid-based polymers such as hydrolysates of ethylene-maleic anhydride copolymers, hydrolysates of styrene-maleic anhydride copolymers, and hydrolysates of isobutylene-maleic anhydride alternating copolymers. Among these, polyethylene glycol or polyvinyl alcohol-based polymers are preferred.

[0060] The polymer (F) may be a homopolymer of a monomer having a polymerizable group, a copolymer of two or more monomers, or a copolymer of a monomer having at least one functional group selected from the group consisting of a carbonyl group, a hydroxyl group, a carboxyl group, a carboxylic anhydride group, and a salt of a carboxyl group and a monomer not having such a group. Two or more polymers (F) may be mixed and used as the polymer (F).

[0061] The molecular weight of the polymer (F) is not particularly limited, but in order to obtain a multilayer structure having better gas barrier properties and mechanical strength, the weight average molecular weight of the polymer (F) is preferably at least 5000, more preferably at least 8000, and even more preferably at least 10000. The upper limit of the weight average molecular weight of the polymer (F) is not particularly limited, and is, for example, at most 1,500,000.

[0062] From the viewpoint of maintaining a good appearance of the multilayer structure, the content of polymer (F) in layer (Y) is preferably less than 50 mass %, more preferably 20 mass % or less, and even more preferably 10 mass % or less, based on the mass of layer (Y), and may be 0 mass %. Polymer (F) may or may not react with components in layer (Y).

[0063] (Organophosphorus Compound (BO)) The organophosphorus compound (BO) is preferably a polymer (BOa) having a plurality of phosphorus atoms or an organophosphorus compound (BOb) described below.

[0064] (Polymer (BOa) Having Multiple Phosphorus Atoms) Examples of the functional group containing a phosphorus atom that the polymer (BOa) has include a phosphate group, a phosphite group, a phosphonate group, a phosphonous group, a phosphinate group, a phosphinous group, and functional groups derived therefrom (for example, salts, (partial) ester compounds, halides (for example, chlorides), dehydrates), etc. Among these, a phosphate group and a phosphonate group are preferred, and a phosphonate group is more preferred.

[0065] Examples of the polymer (BOa) include polymers of phosphono(meth)acrylic acid esters such as 6-[(2-phosphonoacetyl)oxy]hexyl acrylate, 2-phosphonooxyethyl methacrylate, phosphonomethyl methacrylate, 11-phosphonoundecyl methacrylate, and 1,1-diphosphonoethyl methacrylate; polymers of vinylphosphonic acids such as vinylphosphonic acid, 2-propene-1-phosphonic acid, 4-vinylbenzylphosphonic acid, and 4-vinylphenylphosphonic acid; polymers of vinylphosphinic acids such as vinylphosphinic acid and 4-vinylbenzylphosphinic acid; and phosphorylated starch. The polymer (BOa) may be a homopolymer of a monomer having at least one phosphorus atom-containing functional group, or a copolymer of two or more monomers. Furthermore, two or more polymers composed of a single monomer may be used in combination as the polymer (BOa). Among these, polymers of phosphono(meth)acrylic acid esters and polymers of vinylphosphonic acids are preferred, polymers of vinylphosphonic acids are more preferred, and polyvinylphosphonic acid is even more preferred. The polymer (BOa) can also be obtained by homopolymerizing or copolymerizing a vinylphosphonic acid derivative such as a vinylphosphonic acid halide or a vinylphosphonic acid ester, followed by hydrolysis.

[0066] In addition, polymer (BOa) may be a copolymer of a monomer having at least one phosphorus atom-containing functional group and another vinyl monomer. Examples of other vinyl monomers that can be copolymerized with the monomer having a phosphorus atom-containing functional group include (meth)acrylic acid, (meth)acrylic acid esters, acrylonitrile, methacrylonitrile, styrene, nucleus-substituted styrenes, alkyl vinyl ethers, alkyl vinyl esters, perfluoroalkyl vinyl ethers, perfluoroalkyl vinyl esters, maleic acid, maleic anhydride, fumaric acid, itaconic acid, maleimide, phenylmaleimide, etc., and among these, (meth)acrylic acid esters, acrylonitrile, styrene, maleimide, and phenylmaleimide are preferred.

[0067] In order to obtain a multilayer structure having excellent flex resistance, the proportion of the structural units derived from a monomer having a functional group containing a phosphorus atom in all structural units of the polymer (BOa) is preferably 10 mol % or more, more preferably 40 mol % or more, even more preferably 70 mol % or more, particularly preferably 90 mol % or more, and may be 100 mol %.

[0068] Although there are no particular restrictions on the molecular weight of the polymer (BOa), it is preferable that the number average molecular weight is in the range of 1,000 to 100,000. When the number average molecular weight is in this range, it is possible to achieve both a high level of effect of improving the flex resistance of the multilayer structure of the present invention and, when the coating liquid (S) described below is used, viscosity stability of the coating liquid (S).

[0069] When layer (Y) of the multilayer structure contains polymer (BOa), the ratio WBOa / WBI of the mass WBOa of the polymer (BOa) to the mass WBI of the inorganic phosphorus compound (BI) in layer (Y) preferably satisfies the relationship 0.01 / 99.99≦WBOa / WBI<6.00 / 94.00, and from the viewpoint of excellent barrier performance, it is more preferable that it satisfies the relationship 0.10 / 99.90≦WBOa / WBI<4.50 / 95.50, it is even more preferable that it satisfies the relationship 0.20 / 99.80≦WBOa / WBI<4.00 / 96.00, and it is particularly preferable that it satisfies the relationship 0.50 / 99.50≦WBOa / WBI<3.50 / 96.50. That is, it is preferable to use a small amount of WBOa, 0.01 or more and less than 6.00, while using a large amount of WBI, 94.00 or more and 99.99 or less. Even when the inorganic phosphorus compound (BI) and / or the organic phosphorus compound (BOa) have reacted in the layer (Y), the inorganic phosphorus compound (BI) and / or the organic phosphorus compound (BOa) constituting the reaction product (D) is regarded as the inorganic phosphorus compound (BI) and / or the organic phosphorus compound (BOa). In this case, the mass of the inorganic phosphorus compound (BI) and / or the organic phosphorus compound (BOa) used to form the reaction product (D) (the mass of the inorganic phosphorus compound (BI) and / or the organic phosphorus compound (BOa) before the reaction) is included in the mass of the inorganic phosphorus compound (BI) and / or the organic phosphorus compound (BOa) in the layer (Y).

[0070] (Organic phosphorus compound (BOb)) The organic phosphorus compound (BOb) has a phosphorus atom having at least one hydroxyl group bonded thereto and a polar group bonded thereto via an alkylene chain or polyoxyalkylene chain having from 3 to 20 carbon atoms. The organic phosphorus compound (BOb) has a lower surface free energy than the metal oxide (A), the inorganic phosphorus compound (BI), and their reaction product (D), and segregates to the surface side during the precursor formation process of the layer (Y). As a result, the flex resistance of the multilayer structure of the present invention and the adhesion between the layer (Y) and a layer directly laminated thereto may be improved.

[0071] Examples of the organic phosphorus compound (BOb) include 3-hydroxypropylphosphonic acid, 4-hydroxybutylphosphonic acid, 5-hydroxypentylphosphonic acid, 6-hydroxyhexylphosphonic acid, 7-hydroxyheptylphosphonic acid, 8-hydroxyoctylphosphonic acid, 9-hydroxynonylphosphonic acid, 10-hydroxydecylphosphonic acid, 11-hydroxyundecylphosphonic acid, 12-hydroxydodecylphosphonic acid, 13-hydroxydotridecylphosphonic acid, 14-hydroxytetradecylphosphonic acid, and 15-hydroxypentadecylphosphonic acid. Phenoxyethanol, 16-hydroxyhexadecylphosphonic acid, 17-hydroxyheptadecylphosphonic acid, 18-hydroxyoctadecylphosphonic acid, 19-hydroxynonadecylphosphonic acid, 20-hydroxyicosylphosphonic acid, 3-hydroxypropyl dihydrogen phosphate, 4-hydroxybutyl dihydrogen phosphate, 5-hydroxypentyl dihydrogen phosphate, 6-hydroxyhexyl dihydrogen phosphate, 7-hydroxyheptyl dihydrogen phosphate, 8-hydroxyoctyl dihydrogen phosphate, 9-hydroxynonyl dihydrogen phosphate, 10-hydroxydecyl dihydrogen phosphate, 11-hydroxyundecyl dihydrogen phosphate, 12-hydroxydodecyl dihydrogen phosphate, 13-hydroxydotridecyl dihydrogen phosphate, 14-hydroxytetradecyl dihydrogen phosphate, 15-hydroxypentadecyl dihydrogen phosphate, 16-hydroxyhexadecyl dihydrogen phosphate, 17-hydroxyheptadecyl dihydrogen hydrogen phosphate, 18-hydroxyoctadecyl dihydrogen phosphate, 19-hydroxynonadecyl dihydrogen phosphate, 20-hydroxyicosyl dihydrogen phosphate, 3-carboxypropyl phosphonic acid, 4-carboxybutyl phosphonic acid, 5-carboxypentyl phosphonic acid, 6-carboxyhexyl phosphonic acid, 7-carboxyheptyl phosphonic acid, 8-carboxyoctyl phosphonic acid, 9-carboxynonyl phosphonic acid, 10-carboxydecyl phosphonic acid, 11-carboxyundecyl phosphonic acid,Examples of such phosphonic acids include 12-carboxydodecylphosphonic acid, 13-carboxydotridecylphosphonic acid, 14-carboxytetradecylphosphonic acid, 15-carboxypentadecylphosphonic acid, 16-carboxyhexadecylphosphonic acid, 17-carboxyheptadecylphosphonic acid, 18-carboxyoctadecylphosphonic acid, 19-carboxynonadecylphosphonic acid, and 20-carboxyicosylphosphonic acid. These may be used alone or in combination of two or more.

[0072] When the layer (Y) of the multilayer structure contains an organic phosphorus compound (BOb), the ratio MBOb / MBI of the number of moles of the organic phosphorus compound (BOb) to the number of moles of the inorganic phosphorus compound (BI) in the layer (Y) is 1.0×10 －４ ≦MBOb / MBI≦2.0×10 －２ It is preferable that the relationship be satisfied, 3.5 × 10 －４ ≦MBOb / MBI≦1.0×10 －２ It is more preferable that the relationship is 5.0 × 10 －４ ≦MBOb / MBI≦6.0×10 －３ It is more preferable that the following relationship is satisfied.

[0073] When layer (Y) contains an organic phosphorus compound (BOb), the atomic ratio of carbon atoms to aluminum atoms (C / Al ratio) in the layer (Y) of the multilayer structure within a range of 5 nm from the surface on the side not in contact with the substrate (X), as measured by X-ray photoelectron spectroscopy (XPS), is preferably in the range of 0.1 to 15.0, more preferably in the range of 0.3 to 10.0, and particularly preferably in the range of 0.5 to 5.0. Having a C / Al ratio on the surface of layer (Y) in the above range may improve the adhesion between layer (Y) and adjacent layers.

[0074] (Crosslinking Agent-Containing Resin Composition (V)) The layer (Y) may have good flex resistance by containing a crosslinking agent-containing resin composition (V). The crosslinking agent-containing resin composition (V) is composed of a hydroxyl group-containing resin and a crosslinking agent. Examples of the hydroxyl group-containing resin include hydroxyl group-containing epoxy resins, hydroxyl group-containing polyester resins, hydroxyl group-containing (meth)acrylic resins, hydroxyl group-containing polyurethane resins, vinyl alcohol-based resins, and polysaccharides. Among these, it is preferable to contain a vinyl alcohol-based resin or a polysaccharide, more preferably a vinyl alcohol-based resin, and even more preferably a polyvinyl alcohol resin. As the crosslinking agent, a silicon compound having a glycidyl group, an organic titanium compound, or an organic zirconium compound is preferably used. The mass ratio of the hydroxyl group-containing resin to the crosslinking agent (hydroxyl group-containing resin / crosslinking agent) is preferably 2.0 or more and 200 or less, more preferably 9.0 or more and 60 or less.

[0075] [Layer (W)] In the multilayer structure of the present invention, a layer (W) containing at least one selected from the group consisting of a polymer (F), an organic phosphorus compound (BO), and a crosslinker-containing resin composition (V) may be directly laminated on the surface of the layer (Y) opposite to the substrate (X). The inclusion of the layer (W) in the multilayer structure may improve flex resistance or improve adhesion to the adhesive layer (I') described below. From the viewpoint of clarity of the multilayer structure, it may be preferable not to include the layer (W).

[0076] When the multilayer structure of the present invention includes the layer (W), the layer (W) is preferably directly laminated to the layer (Y). Suitable embodiments of the polymer (F), the organophosphorus compound (BO), and the crosslinking agent-containing resin composition (V) that can be contained in the layer (W) are as described above.

[0077] The layer (W) may further contain other components, such as inorganic acid metal salts such as carbonates, hydrochlorides, nitrates, hydrogencarbonates, sulfates, hydrogensulfates, and borates, organic acid metal salts such as oxalates, acetates, tartrates, and stearates, metal complexes such as cyclopentadienyl metal complexes (e.g., titanocene) and cyano metal complexes (e.g., Prussian blue), layered clay compounds, crosslinking agents, polymer compounds other than the polymer (BOa) and the polymer (F), plasticizers, antioxidants, ultraviolet absorbers, flame retardants, etc. The content of the other components in the layer (W) is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, and may be 2% by mass or less, 1% by mass or less, or 0% by mass (no other components).

[0078] When the multilayer structure of the present invention includes the layer (W), the thickness thereof is preferably 0.005 μm or more from the viewpoint of improving the flex resistance of the multilayer structure of the present invention. Although the upper limit of the thickness of the layer (W) is not particularly limited, it is economically preferable to set the upper limit of the thickness of the layer (W) to 1.0 μm, since the effect of improving the flex resistance reaches saturation at a thickness of 1.0 μm or more.

[0079] [Adhesive layer (I)] The multilayer structure of the present invention may have an adhesive layer (I) between the substrate (X) and the layer (Y). By providing the adhesive layer (I), it may be possible to improve the adhesion between the substrate (X) and the layer (Y). In particular, when the substrate (X) has a surface layer, it is preferable to provide the adhesive layer (I) between the surface layer and the layer (Y), and it is more preferable to provide the adhesive layer (I) after surface-treating the surface layer.

[0080] The adhesive constituting the adhesive layer (I) is not particularly limited as long as it has adhesive properties between the substrate (X) and the layer (Y), and examples thereof include polyurethane adhesives, polyester adhesives, etc. The adhesive properties can sometimes be further enhanced by adding a small amount of additives such as a known silane coupling agent to these adhesives. Examples of the silane coupling agent include silane coupling agents having reactive groups such as an isocyanate group, an epoxy group, an amino group, a ureido group, and a mercapto group.

[0081] Although known polyurethane adhesives can be used, it is preferable to use a two-component polyurethane adhesive in which a polyisocyanate component and a polyol component are mixed and reacted. Commercially available two-component polyurethane adhesives can be used, such as Takelac (registered trademark) and Takenate (registered trademark) manufactured by Mitsui Chemicals, Inc.

[0082] Known polyester adhesives can be used, and commercially available products include, for example, Elitel (registered trademark) KT-0507, KT-8701, KT-8803, KT-9204, KA-5034, KA-3556, KA-1449, KA-5071S, and KZA-1449S (all manufactured by Unitika Ltd.), Vylonal (registered trademark) MD-1200 and Vylonal MD-1480 (all manufactured by Toyobo Co., Ltd.), PES Resin A124GP, and PES Resin A684G (manufactured by Takamatsu Oil & Fat Co., Ltd.). Adding a vinyl alcohol resin, particularly polyvinyl alcohol, to a polyester adhesive can sometimes further enhance adhesion. When a vinyl alcohol resin and a polyester resin are used simultaneously, the mass ratio (vinyl alcohol resin / polyester resin) is preferably 1 / 99 or more and 50 / 50 or less, from the viewpoint of maintaining good adhesion while exhibiting higher peel strength. The polyester resin is preferably a polyester resin having a carboxyl group from the viewpoint of affinity with the vinyl alcohol resin. Furthermore, when used as an adhesive, the polyester resin is preferably an aqueous dispersion. When the polyester resin is an aqueous dispersion, the affinity with the polyvinyl alcohol resin tends to be better.

[0083] The thickness of each adhesive layer (I) is preferably 0.001 to 10.0 μm, more preferably 0.003 to 5.0 μm, even more preferably 0.005 to 1.0 μm, even more preferably 0.007 to 0.1 μm, and particularly preferably 0.01 to 0.03 μm.

[0084] [Other Layers (J)] The multilayer structure of the present invention may include a layer (J) other than the substrate (X), the layer (Y), the layer (W), and the adhesive layer (I) in order to improve various properties (e.g., heat sealability, barrier properties, mechanical properties). Such a multilayer structure of the present invention can be produced, for example, by laminating the layer (Y) to the substrate (X) (if necessary via the adhesive layer (I)), and then adhering or forming the other layer (J) directly or via an adhesive layer (I') described below. Examples of the other layer (J) include, but are not limited to, an ink layer, a polyolefin layer, a thermoplastic resin layer such as an ethylene-vinyl alcohol copolymer resin layer, and the like.

[0085] When the multilayer structure of the present invention includes an ink layer, examples of the ink layer include a film obtained by drying a liquid in which a polyurethane resin containing a pigment (e.g., titanium dioxide) is dispersed in a solvent. However, a film obtained by drying an ink containing a pigment-free polyurethane resin or other resin as a main component, or a resist for forming electronic circuit wiring, may also be used. Examples of coating methods for the ink layer include gravure printing and various other coating methods such as a wire bar, spin coater, and die coater. The thickness of the ink layer is preferably 0.5 to 10.0 μm, and more preferably 1.0 to 4.0 μm.

[0086] By forming the outermost layer of the multilayer structure of the present invention as a polyolefin layer, it is possible to impart heat-sealing properties to the multilayer structure and improve the mechanical properties of the multilayer structure. From the viewpoint of improving heat-sealing properties and mechanical properties, the polyolefin is preferably polypropylene or polyethylene. Furthermore, in order to improve the mechanical properties of the multilayer structure, it is preferable to laminate at least one film selected from the group consisting of a polyester film, a polyamide film, and a hydroxyl group-containing polymer film. From the viewpoint of improving the mechanical properties, polyethylene terephthalate is preferred as the polyester, nylon-6 is preferred as the polyamide, and an ethylene-vinyl alcohol copolymer is preferred as the hydroxyl group-containing polymer.

[0087] The other layer (J) may be a layer formed by extrusion coating lamination. There is no particular limitation on the extrusion coating lamination method that can be used in the present invention, and any known method may be used. In a typical extrusion coating lamination method, a molten thermoplastic resin is fed into a T-die, and the thermoplastic resin is taken out from a flat slit of the T-die and cooled to produce a laminate film.

[0088] Other examples of extrusion coating lamination methods include sandwich lamination and tandem lamination. The sandwich lamination method is a method in which a molten thermoplastic resin is extruded onto one substrate, and a second substrate is supplied from a separate unwinder (unwinder) and bonded together to produce a laminate. The tandem lamination method is a method in which two single lamination machines are connected together to produce a five-layer laminate at once.

[0089] [Adhesive Layer (I')] In the multilayer structure of the present invention, the adhesive layer (I') may be used to enhance adhesion to other members (e.g., other layer (J)). The adhesive layer (I) may be composed of an adhesive resin. The adhesives exemplified for the adhesive layer (I) may also be used as the adhesive constituting the adhesive layer (I'). As the adhesive resin for enhancing adhesion to other members, a two-component reactive polyurethane adhesive in which a polyisocyanate component and a polyol component are mixed and reacted is preferred. Furthermore, the adhesive may be further enhanced by adding a small amount of an additive, such as a known silane coupling agent, to the anchor coating agent or adhesive. Examples of silane coupling agents include, but are not limited to, silane coupling agents having a reactive group such as an isocyanate group, an epoxy group, an amino group, a ureido group, or a mercapto group. Adhesion to other members may more effectively suppress deterioration of gas barrier properties or appearance when the multilayer structure of the present invention is subjected to processing such as printing or lamination, and may also enhance the drop strength of protective sheets and electronic devices using the multilayer structure of the present invention.

[0090] [Configuration of the multilayer structure, etc.] In the multilayer structure of the present invention, at least one pair of a substrate (X) and a layer (Y) are laminated adjacent to each other. The substrate (X) and the layer (Y) may be laminated directly or via an adhesive layer (I), but when the substrate (X) has a surface layer and is provided with a layer (Y) facing the surface layer, the substrate (X) and the layer (Y) are preferably laminated via the adhesive layer (I), and when the substrate (X) does not have a surface layer, the substrate (X) and the layer (Y) are preferably laminated directly.

[0091] Examples of the structure of the multilayer structure of the present invention are shown below, but the multilayer structure of the present invention is not limited to these. Each specific example may be combined in multiple configurations. Here, " / " means that the layers are laminated directly or via an adhesive layer. (1) Layer (Y) / Substrate (X) (2) Layer (Y) / Substrate (X) / Layer (Y) (3) Substrate (X) / Layer (Y) / Layer (Y) / Substrate (X) (4) Layer (Y) / Substrate (X) / Substrate (X) / Layer (Y) (5) Layer (Y) / Substrate (X) / Layer (Y) / Substrate (X) (6) Layer (Y) / Substrate (X) / Layer (Y) / Substrate (X) / Layer (Y) In the above examples, the substrate (X) preferably includes a PET layer. Furthermore, another layer (J) may be further included. If another layer (J) is included, the other layer (J) may be laminated to the layer (Y) or the substrate (X) via an adhesive layer (I'). The multilayer structure may consist of only the substrate layer (X) and the layer (Y), or may consist of only the substrate layer (X), the layer (Y) and the adhesive layer (I).

[0092] The haze value of the multilayer structure of the present invention, measured in accordance with JIS K7105:1981, is preferably 3% or less, more preferably 2.5% or less, and even more preferably 2.0% or less. A haze value of not more than the upper limit improves the clarity of the multilayer structure. The haze value of the multilayer structure of the present invention may be 0.1% or more, or may be 0.5% or more. The haze value of the multilayer structure can be adjusted by the type and thickness of the substrate (X), the thickness of the layer (Y), etc.

[0093] The water vapor transmission rate of the multilayer structure of the present invention at 40°C and 90% RH measured in accordance with ISO15106-5:2015 is 1 x 10－２ g / m ２ ・day or less is preferable, 5.0 × 10 －３ g / m ２ days or less is more preferable, 3.0 × 10 －３ g / m ２ The water vapor transmission rate of the multilayer structure of the present invention is more preferably 1.0×10 －５ g / m ２ ・It may be 1.0 × 10 days or more. －４ g / m ２ The water vapor transmission rate of the multilayer structure can be adjusted by the type and thickness of the substrate (X), the thickness of the layer (Y), etc.

[0094] [Method for producing a multilayer structure] The matters described for the multilayer structure of the present invention are applicable to the production method of the present invention, so duplicated explanations may be omitted. Furthermore, the matters described for the production method of the present invention are applicable to the multilayer structure of the present invention.

[0095] Examples of the method for producing the multilayer structure of the present invention include a production method including: step (I) of applying a coating liquid (S) containing a metal oxide (A), an inorganic phosphorus compound (BI), and a solvent to at least one surface of a substrate (X) and removing the solvent to form a precursor layer of layer (Y); and step (II) of heat-treating the precursor layer of layer (Y) to form layer (Y), wherein the coating speed of the coating liquid (S) in step (I) is 0.03 cm / s or more and 2.5 cm / s or less per cm of coating width. When producing a multilayer structure containing an organic phosphorus compound (BO) or a polymer (F), the organic phosphorus compound (BO) or the polymer (F) may be contained in the coating liquid (S) used in step (I) to form a layer (Y) containing the organic phosphorus compound (BO) or the polymer (F), or a coating liquid (T) containing the organic phosphorus compound (BO) or the polymer (F) may be prepared, and the coating liquid (T) may be applied to the surface of a precursor layer of the layer (Y) obtained in step (I) or the surface of the layer (Y) obtained in step (II) in step (III) to impregnate the layer (Y) with the organic phosphorus compound (BO) or the polymer (F), or a layer (W) may be provided on the layer (Y). Note that when an adhesive layer (I) is provided between the substrate (X) and the layer (Y), the production method may include a step of providing the adhesive layer (I) on the substrate (X) before step (I).

[0096] [Step (I)] In step (I), a coating liquid (S) containing a metal oxide (A), an inorganic phosphorus compound (BI), and a solvent is applied to at least one surface of a substrate (X) at a speed of 0.03 cm / s to 2.5 cm / s per cm of coating width, and the solvent is then removed to form a precursor layer of the layer (Y). The coating liquid (S) is usually applied to at least one surface of the substrate (X) directly or via an adhesive layer (I). That is, the coating liquid (S) may be applied onto the adhesive layer (I) of a substrate (X) provided with the adhesive layer (I). The coating speed of the coating liquid (S) is preferably 2.4 cm / s or less, more preferably 2.0 cm / s or less, per cm of coating width, from the viewpoint of improving the image clarity of the resulting multilayer structure. The coating speed of the coating liquid (S) is preferably 0.05 cm / s or more, more preferably 0.2 cm / s or more, per cm of coating width, from the viewpoints of image clarity of the resulting multilayer structure, productivity, and coating stability.

[0097] The reason why the coating speed of the coating liquid (S) improves the image clarity of the resulting multilayer structure is unclear, but it is presumed that when the coating speed exceeds 2.5 cm / s per cm of width of the substrate (X), coating streaks that are difficult to see visually are formed. On the other hand, when the coating speed is less than 0.03 cm / s per cm of width, it is presumed that the coating liquid (S) applied to the substrate tends to be repelled from the substrate, making it impossible to properly construct the layer (Y). Furthermore, in order to achieve the effects of the present invention in applying the coating liquid (S), it is essential to control the coating speed relative to the coating width within the above-mentioned range. The reason for this is unclear, but it is thought that the leveling range in the width direction of the coating liquid (S) applied to the substrate (X) increases in proportion to the coating width, which changes the leveling properties after coating.

[0098] The coating liquid (S) is obtained by mixing a metal oxide (A), an inorganic phosphorus compound (BI), and a solvent. Specific means for preparing the coating liquid (S) include a method of mixing a dispersion of the metal oxide (A) with a solution containing the inorganic phosphorus compound (BI); and a method of adding the inorganic phosphorus compound (BI) to a dispersion of the metal oxide (A) and mixing them. The temperature during mixing is preferably 50°C or less, more preferably 30°C or less, and even more preferably 20°C or less. The coating liquid (S) may contain other compounds (e.g., an organic phosphorus compound (BO) or a polymer (F)), and may optionally contain at least one acid compound (Q) selected from the group consisting of acetic acid, hydrochloric acid, nitric acid, trifluoroacetic acid, and trichloroacetic acid.

[0099] The dispersion of metal oxide (A) can be prepared, for example, according to a method employed in a known sol-gel method, by mixing compound (E), water, and, if necessary, an acid catalyst or an organic solvent, and condensing or hydrolytically condensing compound (E). When a dispersion of metal oxide (A) is obtained by condensing or hydrolytically condensing compound (E), the obtained dispersion may be subjected to a specific treatment (such as peptization in the presence of the acid compound (Q)) if necessary. The solvent used to prepare the dispersion of metal oxide (A) is not particularly limited, but alcohols such as methanol, ethanol, and isopropanol; water; or a mixed solvent thereof are preferred.

[0100] The solvent used for the solution containing the inorganic phosphorus compound (BI) may be appropriately selected depending on the type of inorganic phosphorus compound (BI), and preferably contains water. The solvent may contain an organic solvent (e.g., alcohols such as methanol) as long as it does not interfere with the dissolution of the inorganic phosphorus compound (BI).

[0101] The solid content concentration of the coating liquid (S) is preferably 1 to 20 mass %, more preferably 2 to 15 mass %, and even more preferably 3 to 10 mass %, from the viewpoints of the storage stability of the coating liquid and the coatability to the substrate (X). The solid content concentration can be calculated, for example, by dividing the mass of the solid content remaining after distilling off the solvent from the coating liquid (S) by the mass of the coating liquid (S) used for treatment.

[0102] The viscosity of the coating liquid (S), measured with a Brookfield rotational viscometer (SB type viscometer: rotor No. 3, rotation speed 60 rpm), at the temperature during coating is preferably 3000 mPa·s or less, more preferably 2500 mPa·s or less, and even more preferably 2000 mPa·s or less. A viscosity of 3000 mPa·s or less improves the leveling properties of the coating liquid (S), allowing a multilayer structure with superior appearance to be obtained. Furthermore, the viscosity of the coating liquid (S) is preferably 50 mPa·s or more, more preferably 100 mPa·s or more, and even more preferably 200 mPa·s or more.

[0103] In the coating liquid (S), the molar ratio of aluminum atoms to phosphorus atoms is preferably in the range of 1.0:1.0 to 3.6:1.0, more preferably 1.1:1.0 to 3.0:1.0, and particularly preferably 1.11:1.00 to 1.50:1.00. The molar ratio of aluminum atoms to phosphorus atoms can be calculated by subjecting a dried product of the coating liquid (S) to X-ray fluorescence analysis.

[0104] The coating method of the coating liquid (S) is not particularly limited, and known methods can be used, such as roll coating, gravure coating, screen printing, reverse coating, kiss coating, die coating, metalling bar coating, chamber doctor combined coating, and bar coating.

[0105] The method for removing the solvent (drying treatment) after application of the coating liquid (S) is not particularly limited, and any known drying method can be applied. Examples of the drying method include hot air drying, hot roll contact drying, infrared heating, and microwave heating.

[0106] The drying temperature is preferably lower than the flow initiation temperature of the substrate (X). The drying temperature after application of the coating liquid (S) may be, for example, about 60°C or higher and 180°C or lower, more preferably 60°C or higher and lower than 140°C, even more preferably 70°C or higher and lower than 130°C, and particularly preferably 80°C or higher and lower than 120°C. The drying time is not particularly limited, but is preferably 1 second or higher and lower than 1 hour, more preferably 5 seconds or higher and lower than 15 minutes, and even more preferably 5 seconds or higher and lower than 300 seconds. In particular, when the drying temperature is 100°C or higher (e.g., 100 to 140°C), the drying time is preferably 1 second or higher and lower than 4 minutes, more preferably 5 seconds or higher and lower than 4 minutes, and even more preferably 5 seconds or higher and lower than 3 minutes. When the drying temperature is lower than 100°C (e.g., 60 to 99°C), the drying time is preferably 3 minutes or higher and lower than 1 hour, more preferably 6 minutes or higher and lower than 30 minutes, and even more preferably 8 minutes or higher and lower than 25 minutes. When the drying treatment conditions of the coating liquid (S) are within the above range, a multilayer structure having better gas barrier properties tends to be obtained. By removing the solvent through the drying, a precursor layer of the layer (Y) is formed.

[0107] When layers (Y) are laminated on both sides of a substrate (X), for example, a coating liquid (S) is applied to one side of the substrate (X) and the solvent is removed to form a first layer (a precursor layer of the first layer (Y)), and then a coating liquid (S) is applied to the other side of the substrate (X) and the solvent is removed to form a second layer (a precursor layer of the second layer (Y)). The compositions of the coating liquids (S) applied to each side may be the same or different.

[0108] [Step (II)] In step (II), the precursor layer of layer (Y) formed in step (I) is heat-treated to form layer (Y). In step (II), a reaction to produce reaction product (D) proceeds. To ensure that the reaction proceeds sufficiently, the heat treatment temperature is preferably 140°C or higher, more preferably 170°C or higher, even more preferably 180°C or higher, and particularly preferably 190°C or higher. A low heat treatment temperature increases the time required to achieve a sufficient reaction rate, resulting in reduced productivity. The heat treatment temperature varies depending on the type of substrate (X). For example, when a thermoplastic resin film made of a polyamide resin is used as the substrate (X), the heat treatment temperature is preferably 270°C or lower. Furthermore, when a thermoplastic resin film made of a polyester resin is used as the substrate (X), the heat treatment temperature is preferably 240°C or lower. The heat treatment may be performed in an air atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like. The heat treatment time is preferably from 1 second to 1 hour, more preferably from 1 second to 15 minutes, and even more preferably from 5 to 300 seconds.

[0109] Step (II) preferably includes a first heat treatment step (II-1) and a second heat treatment step (II-2). When the heat treatment is performed in two or more stages, the temperature of the second heat treatment (hereinafter referred to as the second heat treatment) is preferably higher than the temperature of the first heat treatment (hereinafter referred to as the first heat treatment), more preferably 15°C or more higher than the temperature of the first heat treatment, even more preferably 20°C or more higher, and particularly preferably 30°C or more higher.

[0110] Furthermore, the heat treatment temperature in step (II) (the first heat treatment temperature in the case of two or more heat treatment stages) is preferably higher than the drying temperature in step (I), preferably by 30°C or more, more preferably by 50°C or more, even more preferably by 55°C or more, and particularly preferably by 60°C or more, in order to obtain a multilayer structure having good properties.

[0111] When the heat treatment in step (II) is performed in two or more stages, the temperature of the first heat treatment is preferably 140°C or higher but lower than 200°C, and the temperature of the second heat treatment is more preferably 180°C or higher but lower than 270°C. The temperature of the second heat treatment is preferably higher than the first heat treatment temperature, more preferably 15°C or higher, and even more preferably 25°C or higher. In particular, when the heat treatment temperature is 200°C or higher, the heat treatment time is preferably 0.1 seconds to 10 minutes, more preferably 0.5 seconds to 15 minutes, and even more preferably 1 second to 3 minutes. When the heat treatment temperature is lower than 200°C, the heat treatment time is preferably 1 second to 15 minutes, more preferably 5 seconds to 10 minutes, and even more preferably 10 seconds to 5 minutes.

[0112] [Step (III)] In the method for producing a multilayer structure of the present invention, when an organic phosphorus compound (BO), a polymer (F), and / or other components are used, the method may include step (III) of applying a coating liquid (T) obtained by mixing the organic phosphorus compound (BO), the polymer (F), and / or other components and a solvent onto the precursor layer of layer (Y) obtained in step (I), layer (Y) obtained in step (II), or the precursor layer of layer (Y) obtained after step (II-1), followed by a drying treatment. When step (III) is performed after step (II-1), it is preferable to perform step (II-2) after the drying treatment of step (III). In step (III), the amount of coating of the coating liquid (T) may be increased to form layer (W) on layer (Y).

[0113] The solvent used in the coating liquid (T) may be appropriately selected depending on the types of the organic phosphorus compound (BO), the polymer (F) and / or other components, but is preferably an alcohol such as methanol, ethanol, isopropanol, or the like; water; or a mixed solvent thereof.

[0114] The solid content concentration in the coating liquid (T) is preferably 0.01 to 60 mass%, more preferably 0.1 to 50 mass%, and even more preferably 0.2 to 40 mass%, from the viewpoints of storage stability and coatability of the solution. The solid content concentration can be determined by the same method as that described for the coating liquid (S).

[0115] As with the application of the coating liquid (S), the method for applying the coating liquid (T) is not particularly limited, and known methods can be used.

[0116] The conditions for removing the solvent (drying treatment) after application of the coating liquid (T) in the step (III) can be the same as the conditions for the drying treatment after application of the coating liquid (S) in the step (I).

[0117] [Step (IV)] The method for producing a multilayer structure of the present invention may include a step of, before carrying out step (I), subjecting the substrate (X) to a surface treatment as necessary and then providing an adhesive layer (I). More preferably, the production method may include a step (IV) of applying a coating liquid (R) containing a PVA-based resin, a polyester-based resin, and a solvent onto the substrate (X) and then removing the solvent to form the adhesive layer (I).

[0118] The coating liquid (R) may be obtained, for example, by mixing the PVA-based resin, the polyester-based resin, and the solvent as they are, or by mixing a solution or dispersion containing the PVA-based resin with a solution or dispersion containing the polyester-based resin. Among these, from the viewpoint of uniformity of the solution, it is preferable to obtain the coating liquid (R) by mixing an aqueous solution of the PVA-based resin with a dispersion of the polyester-based resin.

[0119] The solvent used in the coating liquid (R) is not particularly limited, but is preferably water as the main component, or may be water alone. When water is used as the main component, alcohols such as methanol, ethanol, and isopropanol are preferably used as other solvents.

[0120] The solid content concentration of the coating liquid (R) is preferably 0.01 to 10 mass % from the viewpoints of the storage stability of the coating liquid and the coatability to the substrate (X). The solid content concentration can be calculated, for example, by dividing the mass of the solid content remaining after distilling off the solvent from the coating liquid (R) by the mass of the coating liquid (R) used for treatment.

[0121] The coating method of the coating liquid (R) is not particularly limited, and a known method can be adopted, such as a casting method, a dipping method, a roll coating method, a gravure coating method, a screen printing method, a reverse coating method, a spray coating method, a kiss coating method, a die coating method, a metaling bar coating method, a coating method using a chamber doctor, a curtain coating method, and a bar coating method.

[0122] The method for removing the solvent from the coating liquid (R) after application to the substrate (X) is not particularly limited, and any known drying method can be applied. Examples of the drying method include hot air drying, hot roll contact drying, infrared heating, and microwave heating.

[0123] [Electronic Device Protective Sheet and Electronic Device] An electronic device using the multilayer structure of the present invention comprises an electronic device main body and a protective sheet that protects the surface of the electronic device main body. The electronic device protective sheet of the present invention includes the multilayer structure of the present invention. The electronic device protective sheet of the present invention may be composed solely of the multilayer structure of the present invention, or may be composed of the multilayer structure of the present invention and other components. The electronic device protective sheet of the present invention has high barrier properties and clarity. Therefore, by using the protective sheet of the present invention, an electronic device can be obtained that is less susceptible to deterioration even in harsh environments and has high clarity of transmitted images. For example, when used in a substrate film for electronic paper, it can be suitably used as a protective material for electronic paper ink, which is sensitive to moisture.

[0124] The electronic device of the present invention may be a photoelectric conversion device, an information display device, or a lighting device. Examples of photoelectric conversion devices include various solar cells and other photoelectric conversion devices. Examples of information display devices include liquid crystal displays, organic electroluminescence displays, plasma displays, electronic paper, and other information display devices. Examples of lighting devices include LED lighting, organic electroluminescence lighting, and other lighting devices.

[0125] The electronic device of the present invention can be particularly preferably used as a device including an optical element. The optical element is appropriately selected depending on the application of the electronic device of the present invention. Here, the optical element in the present invention has an optical function, and the optical function can include, for example, an information display function, a light-emitting function, etc. When an optical element having an information display function is used as the optical element, the electronic device of the present invention can be used as an information display device, and when an optical element having a light-emitting function is used as the optical element, the electronic device of the present invention can be used as a light-emitting device (illumination device).

[0126] Examples of the optical element having the information display function include a liquid crystal cell used in a liquid crystal display device, an organic EL element used in an organic EL display device, and an electronic paper element (particle migration type, liquid crystal type, electrochemical type, etc.) used in an electronic paper device. Here, by using a liquid crystal cell as the optical element, the optical device of the present invention becomes a liquid crystal display device, by using an organic EL element, it becomes an organic EL display device, and by further using an electronic paper element, it becomes an electronic paper device.

[0127] The liquid crystal cell, organic EL element, and electronic paper element are not particularly limited, and generally known elements can be used.

[0128] The multilayer structure of the present invention can also be used as a film called a substrate film, such as a substrate film for LCDs, organic EL displays, or electronic paper. In this case, the multilayer structure may serve as both a substrate and a protective sheet. Furthermore, the electronic device to be protected by the protective sheet is not limited to the above examples, and may also be, for example, an IC tag, an optical communication device, a fuel cell, or the like.

[0129] The electronic device protective sheet of the present invention may include a surface protective layer disposed on one surface of the multilayer structure. The surface protective layer is preferably a layer made of a highly transparent and scratch-resistant resin. Furthermore, the surface protective layer in a protective sheet for a device that may be used outdoors, such as a solar cell, is preferably made of a resin with high weather resistance (e.g., light resistance). Furthermore, when protecting a surface that requires light transmission, a surface protective layer with high light transmissivity is preferred. Examples of materials for the surface protective layer (surface protective film) include acrylic resin, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose, cycloolefin polymer, ethylene-tetrafluoroethylene copolymer (ETFE), polytetrafluoroethylene, 4-fluoroethylene-perchloroalkoxy copolymer, 4-fluoroethylene-6-fluoropropylene copolymer, 2-ethylene-4-fluoroethylene copolymer, poly-3-chlorofluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride.

[0130] To enhance the durability of the surface protective layer, various additives (e.g., ultraviolet absorbers) may be added to the surface protective layer. A preferred example of a highly weather-resistant surface protective layer is an acrylic resin layer to which an ultraviolet absorber has been added. Examples of ultraviolet absorbers include, but are not limited to, benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based, nickel-based, and triazine-based ultraviolet absorbers. In addition, other stabilizers, light stabilizers, antioxidants, etc. may be used in combination.

[0131] Furthermore, in order to enhance the durability of the surface protective layer, a weather-resistant coating such as a hard coat may be applied to the surface. The type of coating is not particularly limited, and known materials can be used.

[0132] The configuration of the protective sheet is not particularly limited, but the following configurations may be suitably used, for example: (1) multilayer structure (2) multilayer structure / adhesive layer / polyethylene terephthalate (3) multilayer structure / adhesive layer / triacetyl cellulose (4) multilayer structure / adhesive layer / acrylic resin (5) multilayer structure / adhesive layer / polycarbonate (6) multilayer structure / adhesive layer / cycloolefin polymer (7) multilayer structure / adhesive layer / ETFE When the multilayer structure of the present invention is laminated with another material, it may be preferable to arrange the other material on the outside to protect the multilayer structure.

[0133] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples, and many modifications can be made by those skilled in the art within the scope of the technical concept of the present invention. Analysis and evaluation in the following examples and comparative examples were carried out as follows.

[0134] <Materials used in the Examples and Comparative Examples> PET23-A: Biaxially oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc., "Lumirror (trademark) U403" (product name), with surface layers on both sides, thickness 23 μm, image clarity 94%, MD heat shrinkage 2.16% PET23-B: Biaxially oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc., "Lumirror (trademark) XW731C" (product name), with surface layers on one side, thickness 23 μm, image clarity 93%, MD heat shrinkage 2.79% PET23-C: Biaxially oriented polyethylene terephthalate film; manufactured by Hyosung Co., Ltd., "RH210" (product name), with surface layers on both sides, thickness 23 μm, image clarity 94%, MD heat shrinkage 2.70% PET23-D: Biaxially oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc., "Lumirror (trademark) S105" (product name), thickness 23 μm, image clarity 83%, MD heat shrinkage 3.00% PET38: Biaxially oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc., "Lumirror (trademark) U483" (product name), with surface layers on both sides, thickness 38 μm, image clarity 94%, MD heat shrinkage 2.05% PET50: Biaxially oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc., "Lumirror (trademark) U403" (product name), with surface layers on both sides, thickness 50 μm, image clarity 94%, MD heat shrinkage 2.04% PET75: Biaxially oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc., "Lumirror (trademark) U483" (product name), with surface layers on both sides, thickness 75 μm, image clarity 93%, MD heat shrinkage 2.08% PET12: Biaxially oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc., "Lumirror (trademark) P60" (product name), thickness 12 μm, image clarity 82%, MD heat shrinkage 3.12% The image clarity and MD heat shrinkage of the above materials were measured according to the methods described in the evaluation methods (5) Image clarity and (2) MD heat shrinkage described below.

[0135] <Evaluation Method> (1) Measurement of Maximum Absorption Wave Number (Imax) of Infrared Absorption Spectrum The layer (Y) of the multilayer structure obtained in the Examples and Comparative Examples was measured by an attenuated total reflection method using a Fourier transform infrared spectrophotometer. －１The maximum absorption wave number (Imax) in the region was calculated. The measurement conditions were as follows: Apparatus: Spectrum One manufactured by PerkinElmer Co., Ltd. Measurement mode: Attenuated total reflection method Measurement region: 800 to 1400 cm －１

[0136] (2) MD shrinkage rate The substrate (X) used in the examples and comparative examples was cut to 12 cm x 12 cm, and a 6 cm x 6 cm (36 squares) grid was drawn in the center so that each square was approximately 1 cm (MD direction) x 1 cm (TD direction) to prepare a measurement sample, and the length of each square parallel to the MD direction was measured with a vernier caliper. Subsequently, the measurement sample was left to stand in a dryer at 210 ° C. for 3 minutes, and after removal, the length of each square parallel to the MD direction was measured again with a vernier caliper. The shrinkage rate of the length of each square parallel to the MD direction before and after leaving the dryer was calculated, and the average value was taken as the MD shrinkage rate.

[0137] (3) Thickness The multilayer structures obtained in the examples and comparative examples were cut using a focused ion beam (FIB) to prepare slices for cross-sectional observation. The prepared slices were fixed to a sample base with carbon tape and subjected to platinum ion sputtering at an acceleration voltage of 30 kV for 30 seconds. The cross section of the multilayer structure was observed using a field emission transmission electron microscope, and the thickness of each layer and the thickness of the multilayer structure as a whole were calculated. The measurement conditions were as follows. The thickness was the average of the measurements at five locations. Apparatus: JEM-2100F manufactured by JEOL Ltd. Acceleration voltage: 200 kV Magnification: 250,000x

[0138] (4) Water Vapor Permeability The multilayer structures obtained in the Examples and Comparative Examples were attached to a water vapor permeability measuring device, and the water vapor permeability was measured by a differential pressure method in accordance with ISO 15106-5:2015. The measurement conditions were as follows. The lower the water vapor permeability, the better the water vapor barrier properties were judged to be. Device: DELTAPERM manufactured by TECHNOLOX Corporation Temperature: 40°C Humidity on the water vapor supply side: 90% RH

[0139] (5) Image clarity The substrate (X) used in the examples and comparative examples or the multilayer structures obtained in the examples and comparative examples was attached to an image clarity measuring device, and image clarity was measured in accordance with ISO 17221:2014. The measurement conditions were as follows, and the average value of five measurements was taken as the measured value. Device: Image clarity measuring device IC-T manufactured by Suga Test Instruments Co., Ltd. Optical comb width: 0.25 mm

[0140] (6) Haze The multilayer structures obtained in the examples and comparative examples were attached to a haze meter HR-100 (manufactured by Murakami Color Research Laboratory Co., Ltd.), and the haze was measured in accordance with JIS K7105: 1981. The measurement was carried out five times, and the average value was taken as the measured value.

[0141] (7) Clarity The electronic device protection sheets obtained in the Examples and Comparative Examples were placed on the surface of any image display device with the laminated material side facing up, and the clarity of the characters displayed on the image display device was evaluated. Ten panelists evaluated the characters as follows: A: clearly displayed characters; B: characters with slightly blurred edges; and C: characters with a hazy overall appearance. The most common evaluation was used to evaluate the clarity. If there were multiple most common evaluations, the multiple evaluations were recorded together.

[0142] (8) Oxygen Permeability The multilayer structures obtained in the examples and comparative examples were cut into 10 mm x 10 mm pieces. The cut-out multilayer structures were attached to an oxygen permeability measuring device, and the oxygen permeability was measured by the isobaric method. The measurement conditions were as follows. Device: OX-TRAN2 / 21 manufactured by MOCON Corporation Temperature: 20°C Humidity on oxygen supply side: 85% RH Humidity on carrier gas side: 85% RH Carrier gas flow rate: 10 mL / min Oxygen pressure: 1.0 atm Carrier gas pressure: 1.0 atm

[0143] <Production Example of Coating Liquid (S-1)> 230 parts by mass of distilled water was heated to 70°C while stirring. 88 parts by mass of triisopropoxyaluminum was added dropwise to the distilled water over 1 hour, and the liquid temperature was gradually raised to 95°C. Hydrolysis and condensation were carried out by distilling off the generated isopropanol. 4.0 parts by mass of a 60% by mass aqueous nitric acid solution was added to the resulting liquid, and the mixture was stirred at 95°C for 3 hours to deflocculate the particle aggregates of the hydrolysis and condensation product. The liquid was then concentrated to a solids concentration of 10% by mass in terms of aluminum oxide, yielding a solution. 54.29 parts by mass of distilled water and 18.80 parts by mass of methanol were added to 22.50 parts by mass of the resulting solution, and the mixture was stirred until uniform, yielding a dispersion. Subsequently, 4.41 parts by mass of an 85% by mass aqueous phosphoric acid solution was added dropwise to the dispersion while stirring, while maintaining the liquid temperature at 15°C. Further, 18.80 parts by mass of the methanol solution was added dropwise, and stirring was continued at 15°C until the viscosity reached 1,500 mPa s, to obtain the target coating solution (S-1). The molar ratio of aluminum atoms to phosphorus atoms in the coating solution (S-1) was aluminum atoms:phosphorus atoms = 1.15:1.00.

[0144] <Production Example of Coating Liquid (R-1)> 4.8 parts by mass of PVA "Kuraray Poval (registered trademark) 48-80" and 95.2 parts by mass of water were mixed and stirred at room temperature for 5 hours to dissolve the "Kuraray Poval (registered trademark) 48-80" and obtain a PVA aqueous solution. Next, 0.8 parts by mass of polyester-based aqueous dispersion "Elitell (registered trademark) KA-5071S" (manufactured by Unitika Ltd.), 1.2 parts by mass of the PVA aqueous solution, 68.1 parts by mass of water, and 29.9 parts by mass of methanol were mixed and stirred for 1 hour to obtain coating liquid (R-1).

[0145] Example 1: PET23-A (width 21 cm) was used as the substrate (X-1). A corona treatment device TEC-4AC manufactured by Kasuga Electric Co., Ltd. was used to treat the substrate at 130 W·min / m ２A surface treatment was performed on one side of the substrate at a strength of 1000000000000000. On one side of the surface-treated substrate, a coating liquid (R-1) was applied using a bar coater so that the thickness after drying would be 10 nm. The coated substrate was dried at 140 ° C. for 1 minute, and an adhesive layer (I-1) was formed on one side of the substrate. On one side of the substrate on which the adhesive layer (I-1) was formed, a coating liquid (S-1) was applied using a bar coater so that the thickness after drying would be 0.4 μm, under conditions of a coating speed of 12.6 cm / s (coating speed per 1 cm of coating width is 0.6 cm / s). The coated substrate was dried at 120 ° C. for 3 minutes and then heat-treated at 180 ° C. for 1 minute, and a precursor layer of layer (Y-1) was formed on the substrate. Next, surface treatment was performed on the other side using the same method, and then an adhesive layer (I-1) and a precursor layer of layer (Y-1) were formed. The resulting film having the precursor layer of layer (Y-1) formed thereon was heat-treated at 210°C for 1 minute to obtain a multilayer structure of layer (Y-1) (0.4 µm) / adhesive layer (I-1) (10 nm) / substrate (X-1) (23 µm) / adhesive layer (I-1) (10 nm) / layer (Y-1) (0.4 µm). Layer (Y-1) of the resulting multilayer structure and the multilayer structure were evaluated according to the methods described in the evaluation methods (1), (3), (4), (5), (6), and (8) above. The results are shown in Table 1.

[0146] Six sheets of the resulting multilayer structure were prepared, and an adhesive layer was formed on one side of each sheet using a two-component polyurethane adhesive (Takelac (registered trademark) A-1102 manufactured by Mitsui Chemicals, Inc. and Takenate (registered trademark) A-3070 manufactured by Mitsui Chemicals, Inc.), and the materials shown below were laminated onto the adhesive layer to produce six types of protective sheets for electronic devices. The clarity of each of the obtained protective sheets for electronic devices was evaluated according to the method described in the evaluation method (7) above. The results are shown in Table 1. Note that clarity 1 to clarity 6 in Table 1 refer to the evaluation of protective sheets for electronic devices laminated with the materials 1 to 6 below, respectively. 1. Lumirror (trademark) U403 (manufactured by Toray Industries, Inc., thickness 50 μm) 2. Cosmoshine SRF (trademark) (manufactured by Toyobo Co., Ltd., thickness 80 μm) 3. Triacetyl cellulose (TAC) film (manufactured by Konica Minolta, Inc., thickness 80 μm) 4. 4. OXIS (trademark) PMMA (manufactured by Okura Kogyo Co., Ltd., thickness 40 μm) 5. Polycarbonate film Pure Ace (trademark) (manufactured by Teijin Limited, thickness 70 μm) 6. Zeonor Film (trademark) (manufactured by Zeon Corporation, thickness 70 μm)

[0147] Example 2 A multilayer structure and a protective sheet for electronic devices were produced and evaluated in the same manner as in Example 1, except that PET23-B was used instead of PET23-A used in Example 1 and the adhesive layer (I-1) was not provided on the side not having the surface layer. The results are shown in Table 1.

[0148] Examples 3 to 6, Comparative Example 1 Multilayer structures and protective sheets for electronic devices were produced and evaluated in the same manner as in Example 1, except that the substrate (X) shown in Table 1 was used instead of PET23-A used in Example 1. The results are shown in Table 1.

[0149] Example 7 A multilayer structure and a protective sheet for electronic devices were prepared and evaluated in the same manner as in Example 1, except that one surface of the PET23-A used in Example 1 was not surface-treated, and the adhesive layer (I-1) and the layer (Y-1) were not provided, and a multilayer structure of layer (Y-1) (0.4 μm) / adhesive layer (I-1) (10 nm) / (surface-treated surface) substrate (X-1) (23 μm) (untreated surface) was prepared. The results are shown in Table 1.

[0150] Examples 8 to 10, Comparative Examples 2 and 3 Multilayer structures and protective sheets for electronic devices were prepared and evaluated in the same manner as in Example 1, except that the application speed of the coating liquid (S) in Example 1 was changed as shown in Table 1. The results are shown in Table 1. Note that, in the multilayer structure of Comparative Example 3, the coating liquid (S) applied to the substrate was repelled from the substrate, and a uniform layer (Y) could not be formed, and therefore the evaluations of the evaluation methods (4), (5), (6), and (8) were not performed.

[0151] Comparative Example 4 A multilayer structure and a protective sheet for electronic devices were prepared and evaluated in the same manner as in Example 1, except that PET12 was used instead of PET23-A used in Example 1 and the application speed of the coating liquid (S) was changed as shown in Table 1. The results are shown in Table 1.

[0152]

[0153] As shown in Table 1, the multilayer structures of Examples 1 to 10 have high barrier properties and image clarity. Furthermore, a comparison of Examples 1, 8 to 10 and Comparative Examples 2 and 3 shows that the application speed of the coating liquid (S) for forming the layer (Y) has a significant effect on the image clarity of the resulting multilayer structure.

Claims

1. A multilayer structure comprising a substrate (X) and a layer (Y), The layer (Y) contains a reaction product (D) of a metal oxide (A) containing an aluminum atom and an inorganic phosphorus compound (BI), the substrate (X) and the layer (Y) are adjacent to each other, A multilayer structure, wherein the image clarity of the multilayer structure is 90% or more at an optical comb width of 0.25 mm, as measured in accordance with ISO 17221:2014.

2. 2. The multilayer structure according to claim 1, which has a haze value of 3% or less as measured in accordance with JIS K7105:1981.

3. Water vapor transmission rate of 1 x 10 at 40°C and 90% RH measured in accordance with ISO15106-5:2015 －２ g / m ２ 2. The multilayer structure of claim 1, wherein the average particle size is equal to or less than 100 μm.

4. 2. The multilayer structure according to claim 1, wherein the substrate (X) has a heat shrinkage rate in the machine direction when heated at 210°C for 1 minute of 2.90% or less.

5. The multilayer structure according to claim 1, wherein the image clarity of the substrate (X) is 90% or more at an optical comb width of 0.25 mm, as measured in accordance with ISO 17221:2014.

6. The multilayer structure according to claim 1, wherein the substrate (X) has a surface layer.

7. The multilayer structure according to claim 1 , wherein the substrate (X) and the layer (Y) are directly laminated together.

8. The multilayer structure according to claim 1, wherein the substrate (X) and the layer (Y) are laminated via an adhesive layer (I).

9. The multilayer structure according to claim 1, comprising a layer (Y) disposed on each side of a substrate (X).

10. a step (I) of applying a coating liquid (S) containing an aluminum atom-containing metal oxide (A), an inorganic phosphorus compound (BI), and a solvent to at least one surface of the substrate (X), and removing the solvent to form a precursor layer of the layer (Y); and Step (II) of forming layer (Y) by heat-treating the precursor layer of layer (Y). Including, the coating speed of the coating liquid (S) in the step (I) is 0.03 cm / s or more and 2.5 cm / s or less per 1 cm of coating width, A method for producing a multilayer structure, wherein the image clarity of the resulting multilayer structure is 90% or more when measured in accordance with ISO 17221:2014 at an optical comb width of 0.25 mm.

11. A protective sheet for electronic devices, comprising the multilayer structure according to any one of claims 1 to 9.

12. The protective sheet according to claim 11, which is a protective sheet for protecting the surface of a photoelectric conversion device, an information display device, or a lighting device.

13. An electronic device comprising the protective sheet according to claim 11.