Interlayer film, laminate, and method for producing interlayer film

Abstract

This interlayer film contains an ionomer resin and an ultraviolet absorber, ultraviolet absorber being at least one compound selected from the group consisting of compounds having a benzotriazole structure represented by formula (I) and compounds having a triazine structure.　The present invention makes it possible to provide an interlayer film containing an ionomer resin, said film having little coloration while suppressing ultraviolet transmittance. (In the formula, R1 is an organic group having 4 or more carbon atoms, and R2-R8 are each independently a hydrogen atom, a halogen atom, or an organic group having 1-20 carbon atoms.)

Description

Interlayer film, laminate, and method for manufacturing interlayer film

[0001] The present invention relates to an interlayer film, a laminate, and a method for manufacturing an interlayer film.

[0002] Laminated glass is safe because it shatters little even when broken by external impact, and is therefore widely used for window glass in various vehicles such as automobiles, railway vehicles, aircraft, and ships, as well as in buildings. Laminated glass is generally known to be formed by interposing an interlayer film for laminated glass, made of a thermoplastic resin or the like, between a pair of panes of glass to form an integrated glass. When used in buildings, laminated glass is used not only for window glass but also for glass floors, curtain walls, and the like. For these applications, it is sometimes made larger and used as structural glazing.

[0003] Ionomer resins have been used in interlayer films for laminated glass in some cases. Known ionomer resins used in interlayer films for laminated glass include ethylene-unsaturated carboxylic acid copolymers, such as ethylene-(meth)acrylic acid copolymers, in which at least some of the carboxyl groups in the side chains are crosslinked between molecular chains by metal cations (see, for example, Patent Documents 1 to 3).

[0004] International Publication No. 2021 / 002326 Japanese Patent Application Laid-Open No. 2022-120218 Japanese Patent Application Laid-Open No. 2019-77582

[0005] Generally, ionomer resins do not absorb ultraviolet light, so to reduce the ultraviolet transmittance of an interlayer film containing an ionomer resin, it is necessary to blend an ultraviolet absorber in. Examples in Patent Documents 1 to 3 show examples in which an ultraviolet absorber is blended in an ionomer resin.

[0006] However, studies by the present inventors have revealed that adding an ultraviolet absorber to an interlayer film containing an ionomer resin can cause the interlayer film to become discolored, resulting in a decrease in aesthetic appeal. Therefore, an object of the present invention is to provide an interlayer film containing an ionomer resin that exhibits reduced ultraviolet transmittance and minimal discoloration.

[0007] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by an interlayer film containing an ionomer resin and at least one ultraviolet absorber selected from the group consisting of compounds having a benzotriazole structure and compounds having a triazine structure, as represented by the following formula (I), and have thus completed the present invention.

[0008] [1] An interlayer film containing an ionomer resin and an ultraviolet absorber, wherein the ultraviolet absorber is at least one selected from the group consisting of a compound having a benzotriazole structure and a compound having a triazine structure, represented by the following formula (I): (In the above formula, R １ is an organic group having 4 or more carbon atoms, and R ２ ~R ８ each independently represents a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. [2] The interlayer film according to the above [1], wherein the compound having a benzotriazole structure is a compound represented by any one of the following formulas (2) to (4): [3] The interlayer film according to [1] or [2] above, wherein the content of the ultraviolet absorber is 0.01 to 1 part by mass relative to 100 parts by mass of the ionomer resin. [4] The interlayer film according to any one of [1] to [3] above, wherein the ionomer resin contains at least one of magnesium and zinc. [5] The interlayer film according to any one of [1] to [4] above, wherein the interlayer film contains a silane coupling agent. [6] The interlayer film according to [5] above, wherein the silane coupling agent is a silane coupling agent having an epoxy group. [7] The interlayer film according to [5] above, wherein the silane coupling agent is contained in an amount of 0.01% by mass or more and 0.5% by mass or less, when the entire interlayer film is taken as 100% by mass. [8] The interlayer film according to any one of [1] to [7] above, wherein the interlayer film is used as an encapsulant for a solar cell. [9] A resin composition containing an ionomer resin and an ultraviolet absorber, wherein the ultraviolet absorber is at least one selected from the group consisting of a compound having a benzotriazole structure and a compound having a triazine structure represented by the following formula (I): (In the above formula, R １is an organic group having 4 or more carbon atoms, and R ２ ~R ８ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.

[10] The resin composition according to the above [9], wherein the compound having a benzotriazole structure is a compound represented by any one of the following formulas (2) to (4):

[11] The resin composition according to [9] or

[10] above, which is a resin composition obtained by kneading an ionomer resin with a mixture of the ultraviolet absorber and an ethylene-(meth)acrylic acid copolymer.

[12] A laminate comprising the interlayer film according to any one of [1] to [8] above and a pair of substrates, wherein the interlayer film is disposed between the pair of substrates.

[13] The laminate according to

[12] above, wherein the substrate is a substrate selected from the group consisting of organic material substrates and inorganic material substrates.

[14] The laminate according to

[12] or

[13] above, which is laminated glass.

[15] The laminate according to

[12] or

[13] above, which is laminated glass for building structures.

[16] A display comprising the laminate according to

[12] or

[13] above.

[17] A photovoltaic cell comprising the laminate according to

[12] or

[13] above.

[18] The method for producing an interlayer film according to any one of the above [1] to [8], comprising: a step of kneading the ionomer resin with a mixture of the ultraviolet absorber and an ethylene-(meth)acrylic acid-based copolymer to obtain a resin composition; and a step of extruding the resin composition.

[0009] According to the present invention, it is possible to provide an interlayer film that has reduced ultraviolet transmittance and is less colored.

[0010] FIG. 2 is a diagram for explaining λ1-λ2 in the present invention.

[0011] [Interlayer film] The interlayer film of the present invention contains an ionomer resin and an ultraviolet absorber, and the ultraviolet absorber is at least one type of interlayer film selected from the group consisting of compounds having a benzotriazole structure and compounds having a triazine structure, as represented by the following formula (I):

[0012] <Ultraviolet Absorber> The interlayer film of the present invention contains an ultraviolet absorber. The inclusion of an ultraviolet absorber improves the ultraviolet shielding properties of the interlayer film. The ultraviolet absorber is at least one selected from the group consisting of compounds having a benzotriazole structure and compounds having a triazine structure, as represented by the following formula (I). The inclusion of such a specific ultraviolet absorber makes it easier to suppress discoloration of the interlayer film. Although the reason for this is unclear, it is thought that the use of an ultraviolet absorber having a specific structure makes it difficult for metal ions contained in the ionomer resin to coordinate to the ultraviolet absorber, thereby suppressing discoloration of the interlayer film.

[0013] (In the above formula, R １ is an organic group having 4 or more carbon atoms, and R ２ ~R ８ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.

[0014] R in the above formula (I) １ is an organic group having 4 or more carbon atoms. This makes it easier to suppress coloration of the interlayer film. The reason for this is not clear, but １ is a group located at the ortho position of the hydroxyl group in formula (I), and because this is an organic group having 4 or more carbon atoms, it is thought that coordination between the ultraviolet absorber and the metal contained in the ionomer resin can be easily suppressed, and as a result, coloration of the interlayer film can be suppressed.

[0015] R １ From the viewpoint of suppressing coloration of the interlayer film, R is preferably an organic group having 4 to 20 carbon atoms, and more preferably an organic group having 4 to 10 carbon atoms. １ may contain an oxygen atom, a nitrogen atom, a sulfur atom, etc., but is preferably a hydrocarbon group. １ is preferably a hydrocarbon group having 4 or more carbon atoms, more preferably a hydrocarbon group having 4 to 20 carbon atoms, and even more preferably a hydrocarbon group having 4 to 10 carbon atoms. １Preferably, R has either a quaternary carbon atom or an aromatic ring, or both. It is presumed that such a structure makes it easier to suppress coordination between the ultraviolet absorber and the metal contained in the ionomer resin, and as a result, coloration of the interlayer film can be further suppressed. １ is particularly preferably a group represented by the following formula (a) or formula (b): * in formula (a) and formula (b) represents a bond to the aromatic ring shown in formula (I).

[0016] R in the above formula (I) ２ ~R ８ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine, with chlorine being preferred. The organic group may contain an oxygen atom, a nitrogen atom, a sulfur atom, or the like, or may be a hydrocarbon group. ２ , R ４ , R ５ , R ６ , R ７ , and R ８ are each independently preferably a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylamino group, an anilino group, an acylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, an alkylthio group, or an arylthio group, and are more preferably a hydrogen atom.

[0017] R in the above formula (I) ３ is a hydrogen atom or an organic group having 1 to 20 carbon atoms. The organic group may contain an oxygen atom, a nitrogen atom, a sulfur atom, or the like, or may be a hydrocarbon group. ３ From the viewpoint of suppressing discoloration of the interlayer film, R is preferably an organic group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 10 carbon atoms or an organic group having an ester structure having 1 to 10 carbon atoms. Furthermore, the hydrocarbon group having 1 to 10 carbon atoms preferably has either a quaternary carbon atom or an aromatic ring, or both. ３is particularly preferably a group represented by the following formula (c), formula (d) or formula (e). * in formula (c), formula (d) and formula (e) represents a bond bonded to the aromatic ring shown in formula (I).

[0018] From the viewpoint of suppressing discoloration of the interlayer film of the present invention, among the compounds having a benzotriazole structure of formula (I), any of the compounds of the following formulas (2) to (4) is preferred, and the compound of formula (2) or (3) is more preferred.

[0019] The type of compound having a triazine structure is not particularly limited. A triazine structure refers to an unsaturated six-membered ring structure containing three nitrogen atoms, and specific examples include 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine. Among compounds having a triazine structure, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-(octyloxy)phenol is preferred because it is easy to suppress coloration of the interlayer film.

[0020] The ultraviolet absorber may be a compound having a benzotriazole structure represented by formula (I) or a compound having a triazine structure, but from the viewpoint of improving the ultraviolet shielding properties of the interlayer film, a compound having a benzotriazole structure represented by formula (I) is preferred.

[0021] The content of the ultraviolet absorber in the interlayer film is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and preferably 3 parts by mass or less, more preferably 2 parts by mass or less, even more preferably 1.5 parts by mass or less, and even more preferably 1 part by mass or less, relative to 100 parts by mass of the ionomer resin. When the content of the ultraviolet absorber is at least these lower limits, the ultraviolet shielding performance of the interlayer film is more likely to be improved. On the other hand, when the content of the ultraviolet absorber is at most these upper limits, coloration of the interlayer film is more likely to be suppressed.

[0022] <Ionomer Resin> The interlayer film of the present invention contains an ionomer resin. Examples of the ionomer resin include ionomer resins of ethylene-unsaturated carboxylic acid copolymers. Ionomer resins are typically resins obtained by neutralizing ethylene-unsaturated carboxylic acid copolymers with metal ions. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, 2-ethylacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, fumaric anhydride, itaconic anhydride, monomethyl maleate, and monoethyl maleate. Of these, acrylic acid and methacrylic acid are preferred. Therefore, the ionomer resin is preferably an ionomer resin of ethylene-(meth)acrylic acid copolymer. Examples of metal ions include those of lithium, potassium, sodium, silver, copper, calcium, magnesium, titanium, zinc, aluminum, barium, beryllium, strontium, tin, lead, iron, cobalt, nickel, cadmium, and mercury. Among these, at least one of magnesium and zinc is preferred. The metal ions may be used alone or in combination. When the ionomer resin contains at least one of magnesium and zinc, particularly when it contains magnesium, an appropriate crosslinked structure is formed, which facilitates increasing the glass transition temperature of the interlayer film and increasing its rigidity. On the other hand, the present inventors have discovered that when the metal ion used in the ionomer is magnesium, the interlayer film is more likely to discolor. By using a specific ultraviolet absorber as in the present invention, discoloration can be suppressed even when using an ionomer resin that is prone to discoloration. Note that (meth)acrylic acid refers to at least one of methacrylic acid and acrylic acid, and the same applies to similar terms below.

[0023] When the ionomer resin is an ethylene-unsaturated carboxylic acid copolymer, it typically contains a structural unit (A) derived from an unsaturated carboxylic acid, a structural unit (B) derived from a neutralized product of an unsaturated carboxylic acid, and a structural unit (C) derived from ethylene. When the ionomer resin is an ethylene-(meth)acrylic acid copolymer, it typically contains a structural unit (A) derived from (meth)acrylic acid, a structural unit (B) derived from a neutralized product of (meth)acrylic acid, and a structural unit (C) derived from ethylene. By containing these structural units (A), (B), and (C), the rigidity of the ionomer resin is easily increased.

[0024] The monomer constituting the structural unit (A) is not particularly limited as long as it is an unsaturated carboxylic acid, but is preferably at least one of acrylic acid and methacrylic acid, and more preferably methacrylic acid from the viewpoints of rigidity and adhesiveness. The structural unit (A) is a structural unit that is not neutralized with a metal ion. The structural unit (B) is a neutralized product of a structural unit derived from the above-mentioned unsaturated carboxylic acid, but is preferably a neutralized product of a structural unit derived from at least one of acrylic acid and methacrylic acid, and more preferably a structural unit of a neutralized methacrylic acid. The structural unit (B) is preferably a neutralized unit of the above-mentioned structural unit (A). The structural unit (B) is a structural unit in which the hydrogen ion of the carboxy group in the unsaturated carboxylic acid is substituted with a metal ion. That is, the unsaturated carboxylic acid neutralized product in the structural unit (B) is a metal salt of the unsaturated carboxylic acid. The metal ion in the metal salt is as described above, but is preferably at least one of magnesium and zinc, and particularly preferably magnesium. Therefore, the structural unit (B) preferably contains at least one of magnesium and zinc, and particularly preferably contains magnesium.

[0025] In the ionomer resin, the total content of the structural units (A) and (B) is preferably 10% by mass or more and 25% by mass or less, based on the total amount of the structural units constituting the ionomer resin. When the total content of the structural units (A) and (B) is 10% by mass or more, the transparency, heat resistance, mechanical strength, etc. of the interlayer film can be improved. Furthermore, when the total content is 25% by mass or less, the flexibility, processability, adhesiveness, etc. can be improved. The total content of the structural units (A) and (B) is more preferably 11% by mass or more and 23% by mass or less, and even more preferably 12% by mass or more and 20% by mass or less.

[0026] In the ionomer resin, the content of the structural unit (B) is preferably 4% by mass or more and 18% by mass or less, based on the total amount of structural units constituting the ionomer resin. When the content of the structural unit (B) is 4% by mass or more, the degree of crosslinking of the ionomer resin is increased, and rigidity is easily increased. Furthermore, when the content is 4% by mass or more, transparency and heat resistance are easily improved. Furthermore, by setting the content of the structural unit (B) to 18% by mass or less, flexibility, adhesion, mechanical strength, processability, etc. of the interlayer film are easily improved. The content of the structural unit (B) in the ionomer resin is more preferably 6% by mass or more and 17.5% by mass or less, even more preferably 7% by mass or more and 16% by mass or less, and even more preferably 10% by mass or more and 14% by mass or less.

[0027] The content of the ethylene-derived structural unit (C) is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and even more preferably 82% by mass or more, based on the total amount of structural units constituting the ionomer resin, from the viewpoint of easily increasing the impact resistance of the ionomer resin. Furthermore, from the viewpoints of transparency, mechanical strength, and moldability, the content of the ethylene-derived structural unit (C) is preferably 90% by mass or less, more preferably 89% by mass or less, even more preferably 88% by mass or less, and even more preferably 85% by mass or less.

[0028] In the ionomer resin, the content of the structural unit (A) is not particularly limited, but is preferably 3% by mass or more and 10% by mass or less, more preferably 4% by mass or more and 9% by mass or less, and even more preferably 8% by mass or less, based on the total amount of the structural units constituting the ionomer resin.

[0029] The ionomer resin may contain structural units other than the structural units (A), (B), and (C) (hereinafter also referred to as "other structural units"). Therefore, the ionomer resin may be a copolymer obtained by copolymerizing ethylene and an unsaturated carboxylic acid and neutralizing it with a metal ion, or a copolymer obtained by copolymerizing ethylene, an unsaturated carboxylic acid, and a monomer other than ethylene and an unsaturated carboxylic acid and neutralizing it with a metal ion. An example of such a structural unit is the structural unit (D) derived from an alkyl (meth)acrylate. The inclusion of the structural unit (D) makes it possible to adjust the glass transition temperature (Tg) of the ionomer resin, for example. Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates having approximately 1 to 10 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl. The content of the structural unit (D) derived from alkyl (meth)acrylate is preferably 15% by mass or less, more preferably 8% by mass or less, even more preferably 4.5% by mass or less, and even more preferably 2% by mass or less, from the viewpoint of preventing an unnecessary decrease in glass transition temperature. Furthermore, the content of the structural unit (D) is better as low as possible, from the viewpoint of increasing rigidity without decreasing the glass transition temperature, and may be 0% by mass or more, and it is preferable that the ionomer resin does not contain the structural unit (D).

[0030] In addition, isobutyl (meth)acrylate is generally preferably used as the alkyl (meth)acrylate in ionomer resins, but in the present invention, it is preferable that the ionomer resin does not contain any structural units derived from isobutyl (meth)acrylate, or contains only a small amount of such units. Therefore, the content of structural units derived from isobutyl (meth)acrylate is preferably 15% by mass or less, more preferably 8% by mass or less, even more preferably 4.5% by mass or less, and even more preferably 2% by mass or less. The content of structural units derived from isobutyl (meth)acrylate may be 0% by mass or more, and it is preferable that the ionomer resin does not contain any structural units derived from isobutyl (meth)acrylate.

[0031] Furthermore, the ionomer resin may contain, as other structural units, structural units other than the structural units (A), (B), (C), and (D), and may have, for example, structural units derived from vinyl esters such as vinyl acetate and vinyl propionate.

[0032] In the present invention, the degree of neutralization of the ionomer resin is, for example, 30% or more. From the viewpoint of increasing rigidity, it is preferably more than 40%, more preferably 42% or more, even more preferably 45% or more, and even more preferably 50% or more. Furthermore, in the present invention, by including at least one of magnesium and zinc (particularly magnesium) in the structural unit (B) and increasing the degree of neutralization, it becomes easier to achieve even better rigidity. Furthermore, the degree of neutralization of the ionomer resin is not particularly limited, but from the viewpoint of improving the flexibility, adhesion, mechanical strength, processability, etc. of the interlayer film, it is preferably 95% or less, more preferably 90% or less, even more preferably 80% or less, and even more preferably 75% or less. The degree of neutralization of the ionomer resin refers to the percentage (%) of carboxyl groups neutralized with metal ions out of all carboxyl groups contained in the ionomer resin.

[0033] The degree of neutralization of the ionomer resin can be determined by IR measurement before and after the hydrochloric acid treatment. Specific measurement methods are as described in the Examples below. The content of each structural unit in the ionomer resin can be determined by mass spectrometry and １ H-NMR measurement is carried out, and the degree of neutralization can be calculated from the integrated intensity ratio of the hydrogen peaks derived from each monomer.

[0034] The ionomer resin has a melt mass flow rate (MFR), measured in accordance with JIS K7210:1999 under conditions of 190°C and a load of 2160 g, of, for example, 0.01 g / 10 min or more and 150 g / 10 min or less, preferably 0.01 g / 10 min or more and 50 g / 10 min or less, more preferably 0.1 g / 10 min or more and 30 g / 10 min or less, and even more preferably 0.1 g / 10 min or more and 10 g / 10 min or less, from the viewpoints of processability, mechanical strength, and the like.

[0035] The content of the ionomer resin in the interlayer film is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 88% by mass or more, based on 100% by mass of the entire interlayer film. By setting the ionomer resin content within the above lower limit, the rigidity, interlayer adhesion, and other properties of the resulting laminated glass can be improved. The content of the ionomer resin in the interlayer film may be 100% by mass or less, based on 100% by mass of the entire interlayer film. However, from the viewpoint of including a certain amount or more of additives, it may be, for example, 99.99% by mass or less or 99.9% by mass or less. When the ionomer resin in the interlayer film contains other resin components described below, the content of the ionomer resin in the interlayer film should be a certain amount or less, for example, 98% by mass or less or 97% by mass or less.

[0036] The method for producing the ionomer resin is not particularly limited, and the ionomer resin can be produced by a known method. For example, the ionomer resin can be produced by radically copolymerizing each monomer component under high temperature and high pressure to obtain an ethylene-unsaturated carboxylic acid copolymer, and then reacting the copolymer with a metal compound.

[0037] <Other Resin Components> The interlayer film of the present invention may contain other resin components in addition to the ionomer resin. The ionomer resin may become too viscous during kneading, resulting in reduced extrudability. However, the inclusion of other resin components improves the extrudability of the interlayer film of the present invention. The other resin components are preferably resins compatible with the ionomer resin. From the viewpoint of compatibility with the ionomer resin, the other resin components are preferably ethylene-unsaturated carboxylic acid copolymers. The unsaturated carboxylic acids used in the ethylene-unsaturated carboxylic acid copolymers are as described above. Among these, (meth)acrylic acid is preferred, and methacrylic acid is more preferred. Furthermore, from the viewpoints of compatibility and extrudability, the other resins are preferably copolymers of the same type as the copolymer used in the ionomer resin, and more preferably resins prior to neutralization with metal ions to obtain the ionomer resin. Therefore, when the ionomer resin is an ionomer resin of an ethylene-(meth)acrylic acid copolymer, the other resins are preferably ethylene-(meth)acrylic acid copolymers. When the ionomer resin is an ionomer resin of an ethylene-methacrylic acid copolymer, the other resin is preferably an ethylene-methacrylic acid copolymer.

[0038] When other resin components are used, the content of the other resin components is preferably 1.5% by mass or more and 25% by mass or less, relative to 100% by mass of the entire interlayer film. By setting the content of the other resin components to 2% by mass or more, the viscosity of the ionomer resin is reduced, making it easier to improve extrusion properties. Furthermore, by setting the content to 25% by mass or less, a decrease in rigidity can be prevented even when other resin components are included. The content of the other resin components is more preferably 2.5% by mass or more and 18% by mass or less, and even more preferably 3.5% by mass or more and 12% by mass or less, relative to 100% by mass of the entire interlayer film.

[0039] <Silane Coupling Agent> The interlayer film may contain a silane coupling agent as an additive. The inclusion of a silane coupling agent in the interlayer film facilitates improved adhesion to substrates, glass, and the like. The present inventors have discovered that interlayer films containing ionomer resins have glass adhesion properties that differ from those of interlayer films containing polyvinyl acetal resins. Specifically, they found that interlayer films containing ionomer resins exhibit lower adhesion to the top surface of float glass compared to adhesion to the bottom surface. Further investigations have revealed that adding a silane coupling agent to an interlayer film containing an ionomer resin can achieve excellent adhesion regardless of the glass surface. Examples of the silane coupling agent include those having a functional group, such as a group containing a polymerizable carbon-carbon double bond (e.g., a vinyl group, a (meth)acryloyl group), an amino group, or an epoxy group, and a hydrolyzable group (e.g., an alkoxy group).

[0040] Examples of silane coupling agents having a polymerizable carbon-carbon double bond include vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldiethoxysilane, and 3-acryloxypropyltriethoxysilane. Examples of silane coupling agents having an amino group include N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride. Examples of silane coupling agents having an epoxy group include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane. The interlayer film may contain one type of silane coupling agent alone or two or more types.

[0041] Among these, from the viewpoint of improving adhesion to glass and substrates, silane coupling agents having an amino group are preferred, and among these, silane coupling agents having an ethylenediamine structure such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltriethoxysilane are preferred. Furthermore, from the viewpoint of improving adhesion to glass and substrates and further reducing the yellowness of the interlayer film, silane coupling agents having an epoxy group are more preferred, and among these, 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane are even more preferred.

[0042] From the viewpoint of improving adhesion to glass and substrates, the content of the silane coupling agent in the interlayer film is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.005% by mass or more and 2% by mass or less, even more preferably 0.01% by mass or more and 1% by mass or less, still more preferably 0.01% by mass or more and 0.5% by mass or less, and even more preferably 0.05% by mass or more and 0.5% by mass or less, based on 100% by mass of the entire interlayer film. Although there are no particular upper limits, the content of the silane coupling agent is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, based on 100% by mass of the entire interlayer film.

[0043] <Other Additives> In addition to the above-mentioned ultraviolet absorbers and silane coupling agents, the additives contained in the interlayer film may also include at least one of antioxidants and other known additives.

[0044] Examples of antioxidants include phenolic compounds, phosphoric acid compounds, and sulfur compounds. The antioxidants can prevent the interlayer film from being deteriorated by oxidation and improve durability. The antioxidants may be used alone or in combination of two or more.

[0045] The interlayer film of the present invention may contain other additives in addition to those mentioned above. Examples of such additives include plasticizers, light stabilizers, antistatic agents, surfactants, colorants, foaming agents, lubricants, crystal nucleating agents, crystallization accelerators, crystallization retarders, catalyst deactivators, heat ray absorbers, heat ray reflectors, heat dissipation agents, inorganic fillers, organic fillers, impact resistance improvers, slip agents, crosslinking agents, crosslinking aids, tackifiers, processing aids, mold release agents, hydrolysis inhibitors, antiblocking agents, antifogging agents, flame retardants, flame retardant aids, light diffusing agents, antibacterial agents, antifungal agents, and dispersants.

[0046] <Difference between λ1 and λ2 (λ1-λ2)> The interlayer film of the present invention is preferably an interlayer film in which the difference (λ1-λ2) between the wavelength λ1 (nm) and the wavelength λ2 (nm) described below is 20 nm or less. In transmittance measurements of a laminated glass obtained by sandwiching the interlayer film between two 2.5 mm thick clear glass sheets, the wavelength λ1 is the shortest wavelength (nm) at which the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less in the wavelength range of 300 to 460 nm and in the range of light transmittance of 10% or more. In transmittance measurements performed on a solution of an ultraviolet absorber having the same concentration (mass %) as the ultraviolet absorber contained in the interlayer film under the conditions of an optical path length L (mm) defined by the following standard, the wavelength λ2 is the shortest wavelength (nm) at which the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less in the wavelength range of 300 to 460 nm and in the range of light transmittance of 10% or more. When the thickness of the interlayer film is more than 0 mm and less than 1.5 mm, the optical path length L is 1 mm; when the thickness of the interlayer film is 1.5 mm or more and less than 2.5 mm, the optical path length L is 2 mm; when the thickness of the interlayer film is 2.5 mm or more and less than 3.5 mm, the optical path length L is 3 mm; and when the thickness of the interlayer film is 3.5 mm or more, the optical path length L is the length obtained by rounding off the thickness (mm) of the interlayer film to one decimal place.

[0047] In the present invention, the difference between λ1 and λ2 (λ1 - λ2) is preferably 20 nm or less. When the difference between λ1 and λ2 is 20 nm or less, discoloration of the interlayer film is easily suppressed, resulting in good aesthetics. From the viewpoint of further suppressing discoloration of the interlayer film, the difference between λ1 and λ2 is preferably 15 nm or less, and more preferably 10 nm or less. The lower limit of the difference between λ1 and λ2 is not particularly limited, but is preferably 0 nm. The difference between λ1 and λ2 can be adjusted by the type and amount of ultraviolet absorber and ionomer resin used. The reason why discoloration of the interlayer film can be suppressed when the difference between λ1 - λ2 is a certain value or less is presumed to be as follows.

[0048] FIG. 1 shows a schematic diagram of a transmittance curve (dotted line) obtained by measuring the transmittance of a laminated glass with an interlayer film to calculate λ1, and a transmittance curve (solid line) obtained by measuring the transmittance of a solution to calculate λ2. The interlayer film contains an ionomer resin and an ultraviolet absorber, while the solution contains the same concentration of ultraviolet absorber as the interlayer film but does not contain an ionomer resin. The transmittance curve of the interlayer film (dotted line) is shifted toward longer wavelengths than the transmittance curve of the solution (solid line). This is presumably due to the coordination of metal ions contained in the ionomer resin in the interlayer film with the ultraviolet absorber. The coordination of such metal ions with the ultraviolet absorber is believed to be the cause of interlayer film discoloration. Therefore, when the amount of shift toward longer wavelengths is small, i.e., when the difference between λ1 and λ2 is below a certain level, it is believed that interlayer film discoloration can be suppressed.

[0049] λ1 is preferably 400 nm or more and 430 nm or less. When λ1 is in this range, yellowing of the interlayer film is easily suppressed. From this viewpoint, λ1 is more preferably 410 nm or more and 430 nm or less, and even more preferably 415 nm or more and 425 nm or less.

[0050] In measuring the transmittance of laminated glass including an interlayer film, it is preferable that the light transmittance at a wavelength of 380 nm is 10% or less. When the light transmittance at a wavelength of 380 nm is 10% or less, the ultraviolet ray shielding performance of the interlayer film is further improved. The light transmittance at a wavelength of 380 nm is more preferably 5% or less, even more preferably 4.5% or less, even more preferably 4.0% or less, and even more preferably 2.0% or less. The lower limit of the light transmittance at a wavelength of 380 nm is 0%. In measuring the transmittance of laminated glass including an interlayer film, it is preferable that the light transmittance at a wavelength of 420 nm is 80% or more. When the light transmittance at a wavelength of 420 nm is 80% or more, the transparency of the interlayer film is improved and yellowing is further suppressed. The light transmittance at a wavelength of 420 nm is more preferably 82% or more, even more preferably 84% or more. The upper limit of the light transmittance at a wavelength of 420 nm is 100%.

[0051] In measuring the transmittance of the laminated glass including the interlayer film, the light transmittance at wavelength λ1 is preferably 80% or more, more preferably 82% or more, and even more preferably 84% or more. The upper limit of the light transmittance at λ1 is 100%.

[0052] In measuring the transmittance of a solution containing an ultraviolet absorber, the light transmittance at wavelength λ2 is preferably 80% or more. The light transmittance at wavelength λ1 is more preferably 82% or more, and even more preferably 84% or more. The upper limit of the light transmittance at wavelength λ1 is 100%.

[0053] Next, the methods for calculating λ1 and λ2 will be described. λ1 is the minimum wavelength (nm) at which the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less in a wavelength range of 300 to 460 nm in a region where light transmittance is 10% or more, when measuring the transmittance of a laminated glass obtained by sandwiching an interlayer film between two sheets of clear glass with a thickness of 2.5 mm. Here, the region where light transmittance is 10% or more is the region on the long-wavelength side (right side) of point P on the transmittance curve (dotted line) for the interlayer film in Figure 1. The increase in transmittance (%) with respect to the increase in wavelength (nm) corresponds to the slope of the transmittance curve (dotted line), and λ1 is the minimum wavelength at which this slope is 1 or less.

[0054] λ2 is measured by preparing a solution of the ultraviolet absorber at the same concentration (mass %) as the concentration (mass %) of the ultraviolet absorber contained in the interlayer film. In transmittance measurements of the solution under conditions of an optical path length L (mm), λ2 is the minimum wavelength (nm) at which the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less in a wavelength range of 300 to 460 nm, where the light transmittance is 10% or more. Here, the region where the light transmittance is 10% or more refers to the region on the long-wavelength side (right side) of point Q on the transmittance curve (solid line) of the solution in Figure 1. The increase in transmittance (%) with respect to the increase in wavelength (nm) corresponds to the slope of the transmittance curve (dotted line), and λ2 is the minimum wavelength at which the slope is 1 or less.

[0055] The minimum wavelength at which the slope is 1 or less can be determined as follows. A transmittance curve is generally obtained by scanning a spectrophotometer from short wavelengths to long wavelengths at equal intervals (for example, 5 nm intervals) and plotting the transmittance at each measurement point. If adjacent measurement points are λn (nm) and λm (nm), and the transmittance at λn (nm) is Tn (%) and the transmittance at λm (nm) is Tm (%), the slope of the transmittance curve is calculated as (Tm-Tn) / (λm-λn). In this way, the slope is calculated sequentially from the short wavelength side to the long wavelength side, and the portion where the slope is 1 or less is identified for the first time. If the above-mentioned portions λn (nm) and λm (nm) are the portions where the slope is 1 or less for the first time, the wavelength at the midpoint between λn (nm) and λm (nm) is the above-mentioned λ1 or λ2.

[0056] The solution used in measuring λ2 can be prepared by dissolving the ultraviolet absorber in a solvent. The solvent is not particularly limited as long as it can dissolve the ultraviolet absorber, and various organic solvents, plasticizers, etc. can be used, but it is preferable to use tetrahydrofuran or triethylene glycol-di-2-ethylhexanoate.

[0057] Furthermore, the optical path length L when measuring λ2 needs to be close to the thickness of the interlayer film. That is, when the thickness of the interlayer film is more than 0 mm and less than 1.5 mm, the optical path length L is 1 mm; when the thickness of the interlayer film is 1.5 mm or more and less than 2.5 mm, the optical path length L is 2 mm; when the thickness of the interlayer film is 2.5 mm or more and less than 3.5 mm, the optical path length L is 3 mm; and when the thickness of the interlayer film is 3.5 mm or more, the optical path length L is the length obtained by rounding off the first decimal place of the thickness of the interlayer film. The optical path length L can be adjusted by the type of cell into which the solution is introduced when measuring λ2.

[0058] <Yellowness Index (YI)> From the viewpoint of improving aesthetics, the yellowness index (YI) of the interlayer film of the present invention is preferably 2.5 or less, more preferably 2 or less, and even more preferably 1.5 or less. From the viewpoint of improving aesthetics, the yellowness index per unit thickness of the interlayer film (YI / d) is preferably 2.5 or less, more preferably 2 or less, and even more preferably 1.5 or less. The yellowness index per unit thickness of the interlayer film (YI / d) is the value obtained by dividing the yellowness index (YI) by the thickness (mm) of the interlayer film. The yellowness index is also called the yellow index (YI) and is measured using a spectrophotometer in accordance with JIS K7105.

[0059] (Thickness) The thickness of the interlayer film is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.5 mm or more, even more preferably 0.6 mm or more, and preferably 4 mm or less, more preferably 3.0 mm or less, even more preferably 2.5 mm or less, even more preferably 1.6 mm or less, and even more preferably 1.0 mm or less. When the thickness of the interlayer film is at least these lower limit values, the rigidity and adhesiveness of the interlayer film, as well as the penetration resistance when the interlayer film is used in laminated glass, can be improved. When the thickness of the interlayer film is at most these upper limit values, the transparency of the interlayer film can be easily ensured.

[0060] (Width) The interlayer film of the present invention preferably has a width of 1 m or more. A width of 1 m or more makes the interlayer film suitable for use in large-sized laminated glass, laminated glass for architectural structures, and the like. A width of 1 m or more may make industrial mass production difficult, but mass production can be facilitated by incorporating a resin other than an ionomer resin, such as an ethylene-methacrylic acid copolymer, into the interlayer film. The width of the interlayer film is more preferably 2 m or more. The interlayer film is not particularly limited, but from the viewpoint of improving productivity, it is preferably 5 m or less, and more preferably 4 m or less.

[0061] The interlayer film of the present invention is preferably an extrusion molded product obtained by extrusion molding, as described below. Being an extrusion molded product facilitates industrial mass production of large interlayer films with widths of 1 m or more, as described above. Furthermore, extrusion molded products can have high viscosity, which can reduce productivity. However, productivity can be improved by including a resin other than an ionomer resin, such as an ethylene-methacrylic acid copolymer, in the interlayer film.

[0062] The interlayer film of the present invention is preferably composed of a single layer film. The layers constituting the monolayer film may be composed of a resin composition having the composition described above. That is, the layers constituting the monolayer film may be composed of a resin composition containing an ionomer resin and an ultraviolet absorber, and optionally containing additives. The interlayer film of the present invention may also be a multilayer film having two or more layers. The multilayer film may have the overall composition of the interlayer film as described above, but the resin composition constituting each layer may have the composition described above for the interlayer film. That is, each layer may be composed of a resin composition containing an ionomer resin and an ultraviolet absorber, and optionally containing additives, as described above for the interlayer film. In a multilayer film, the compositions of the layers may be different or the same. In a monolayer film or a multilayer film, the contents of the ionomer resin, ultraviolet absorber, other resin components, and additives in the resin composition constituting each layer may be as described above. However, while the content of each component described above was based on 100% by mass of the interlayer film, in the resin composition constituting each layer, the content of each component is based on 100% by mass of the resin composition instead of 100% by mass of the interlayer film.

[0063] [Method for Manufacturing Interlayer Film] The interlayer film may be prepared by obtaining a resin composition for forming the interlayer film and molding the resin composition. The resin composition may be prepared by mixing components constituting the interlayer film, such as an ionomer resin, an ultraviolet absorber, and additives other than the ultraviolet absorber, if necessary, to obtain a resin composition, and then forming the resulting resin composition into a film by extrusion molding, press molding, roll molding, or the like to obtain the interlayer film. The method for mixing the components to obtain the resin composition is not particularly limited, but a kneading method using an extruder is preferred. Furthermore, when the interlayer film is multilayered, the resin compositions for forming each layer may be prepared, and the resulting resin compositions may be formed into a film by extrusion molding, press molding, roll molding, or the like to form each layer, and the layers may then be laminated to obtain the interlayer film. In this case, the extrusion molding may be performed by co-extrusion. Among the above methods, extrusion molding is preferred for forming the interlayer film. Using extrusion molding allows for efficient production of wide interlayer films.

[0064] In one embodiment, the present invention may produce an interlayer film using a so-called masterbatch. The masterbatch is a mixture (hereinafter sometimes referred to as mixture (A)) of a resin component and an additive. The resin component can be at least one of an ionomer resin and a resin component other than the ionomer resin. The resin component other than the ionomer resin is preferably the other resin component described above, and more preferably an ethylene-(meth)acrylic acid copolymer. The use of a masterbatch allows the additive to be easily mixed into the ionomer resin. Furthermore, by including the other resin component, such as an ethylene-(meth)acrylic acid copolymer, in mixture (A), the viscosity of the resin composition can be effectively reduced, making it easier to knead the resin composition in an extruder, for example. The additives contained in mixture (A) preferably include an ultraviolet absorber, and may also include a silane coupling agent or other additives. The form of mixture (A) is not particularly limited, but is typically in the form of particles such as pellets.

[0065] Even when a masterbatch is used, the interlayer film is preferably formed by extrusion molding. Therefore, in a preferred embodiment, the method for producing an interlayer film may include step (1) of kneading an ionomer resin with a mixture (A) of an ultraviolet absorber and an ethylene-(meth)acrylic acid copolymer to obtain a resin composition, and step (2) of extruding the obtained resin composition. In step (1), the mixing ratio of the mixture (A) to the ionomer resin (mixture (A) / ionomer resin) is preferably 2 / 98 or more and 30 / 70 or less, more preferably 3 / 97 or more and 20 / 70 or less, and even more preferably 4 / 96 or more and 15 / 85 or less, by mass ratio. By setting the mixing ratio within the above range, appropriate amounts of additives and other resin components such as the ethylene-(meth)acrylic acid copolymer can be blended into the resin composition.

[0066] The total content of additives in mixture (A) is preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 15% by mass or less, based on the total amount of mixture (A). By making the total content of additives in mixture (A) equal to or greater than the above-mentioned lower limit, an appropriate amount of additives can be blended into the resin composition without mixing more than necessary of other resin components, such as ethylene-(meth)acrylic acid copolymers, into the resin composition. By making the content of additives in mixture (A) equal to or less than the above-mentioned upper limit, the additives can be properly dispersed in mixture (A).

[0067] The interlayer film of the present invention is preferably disposed between a pair of substrates and used, and more preferably used in a laminate, as described below. The interlayer film may also be used to bond a pair of substrates. The interlayer film is particularly preferably an interlayer film for laminated glass, used in laminated glass. The interlayer film can also be used in applications other than laminates, such as various sealing materials, and specifically, can be used in sealing materials for solar cells.

[0068] <Resin Composition> The present invention can also provide a resin composition containing an ionomer resin and an ultraviolet absorber, wherein the ultraviolet absorber is at least one selected from the group consisting of compounds having a benzotriazole structure and compounds having a triazine structure, as represented by formula (I) above. Furthermore, the resin composition described above is preferably a resin composition obtained by kneading a mixture of an ionomer resin, an ultraviolet absorber, and an ethylene-(meth)acrylic acid copolymer. An interlayer film obtained from the resin composition exhibits ultraviolet blocking properties while suppressing coloration. The resin composition may contain other resin components and additives other than the ultraviolet absorber, as necessary. The contents of the ionomer resin, ultraviolet absorber, other resin components, and each additive in the resin composition may be as described above. However, while the content of each component described above was based on 100% by mass of the interlayer film, in the resin composition, the content of each component is based on 100% by mass of the resin composition instead of 100% by mass of the interlayer film.

[0069] <Laminate> The laminate according to the present invention includes the above-described interlayer film and a pair of substrates, with the interlayer film disposed between the pair of substrates. In the laminate, the pair of substrates may be bonded via the interlayer film. Furthermore, in the laminate, the interlayer film disposed between the pair of substrates may be a single film, or multiple interlayer films may be disposed between the pair of substrates. The multiple interlayer films may be integrated between the substrates, and the pair of substrates may be bonded via the integrated multiple interlayer films. When used in, for example, architectural structures, the interlayer film disposed between the laminates may need to be thick. Using multiple interlayer films makes it easier to relatively increase the thickness of the interlayer film disposed between the laminates.

[0070] The pair of substrates used in the laminate of the present invention is preferably selected from the group consisting of organic material substrates and inorganic material substrates. Examples of organic material substrates include organic resin plates and resin films. Hereinafter, the resin film used as the substrate may be referred to as a substrate resin film. The organic resin plate is also called an organic glass plate. The organic resin plate is not particularly limited, but includes (meth)acrylic plates such as polycarbonate plates and polymethyl methacrylate plates, polyester plates such as acrylonitrile-styrene copolymer plates, acrylonitrile-butadiene-styrene copolymer plates, and polyethylene terephthalate plates, fluorine-based resin plates, polyvinyl chloride plates, chlorinated polyvinyl chloride plates, polypropylene plates, polystyrene plates, polysulfone plates, epoxy resin plates, phenolic resin plates, unsaturated polyester resin plates, and various organic glass plates such as polyimide resin plates. The organic resin plate may be subjected to appropriate surface treatment. Among the above, polycarbonate plates are preferred because of their excellent transparency and impact resistance, and (meth)acrylic plates are preferred because of their high transparency, weather resistance, and mechanical strength, with polycarbonate plates being more preferred. The thickness of the organic resin plate is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.4 mm or more, and is preferably 5.0 mm or less, more preferably 3.0 mm or less.

[0071] The substrate resin film is not particularly limited, but examples thereof include polyester resin films such as (meth)acrylic resin film, polycarbonate film, polyethylene terephthalate (PET) film, and polyethylene naphthalate (PEN) film; polyolefin resin films such as polyethylene film and polypropylene film; cyclic polyolefin (COP) film, triacetyl cellulose (TAC) film, polyethersulfone (PES) resin film, and polyimide resin film. Among these, PET film is preferred. A surface layer such as a hard coat layer made of a (meth)acrylic resin may be provided on the surface of the substrate resin film. The substrate resin film may be a single layer, or may be a laminate of two or more layers. The organic material substrate may also be a functional film containing the substrate resin film. A preferred functional film is a polarizing film (polarizing plate).

[0072] The thickness of the substrate resin film or functional film in the laminate is not particularly limited, but is preferably 30 μm or more, more preferably 50 μm or more, and preferably 500 μm or less, more preferably 450 μm or less. A relatively thick, low-flexibility, and generally unfoldable material is called an organic resin plate, while a relatively thin, generally foldable material is generally called a resin film, but these are not clearly distinguished. Among the above, the organic material substrate is preferably any of a polarizing film (polarizing plate), a PET film, a (meth)acrylic plate, and a polycarbonate plate.

[0073] Examples of inorganic material substrates include inorganic glass plates. The inorganic glass plates are not particularly limited, but include various glass plates such as clear glass, clear float glass, float glass plates, tempered glass, colored glass, polished glass plates, patterned glass plates, wired glass plates, lined glass plates, ultraviolet absorbing glass plates, infrared reflecting glass plates, infrared absorbing glass plates, and green glass. The inorganic glass may be subjected to surface treatment or the like. The thickness of the inorganic glass is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.3 mm or more, even more preferably 0.5 mm or more, and is preferably 5.0 mm or less, even more preferably 3.0 mm or less.

[0074] Here, it is also preferable that both of the pair of substrates are glass. In this case, the laminate becomes laminated glass. That is, the laminated glass of the present invention comprises a pair of glass members and an interlayer film disposed between the pair of glass members. The glass members may be inorganic glass plates or organic glass plates. The two glass members may be made of the same material or different materials. For example, one may be inorganic glass and the other organic glass, but it is preferable that both of the two glass members are inorganic glass or organic glass. The thickness of each of the above glass members is not particularly limited, but is preferably 0.5 mm or more and 5 mm or less, more preferably 0.7 mm or more and 3 mm or less. As described above, the interlayer film disposed between the pair of glass members may be one sheet or multiple sheets.

[0075] The organic material substrate or inorganic material substrate may be appropriately provided with an electrode, a sensor, or the like. The electrode is composed of a conductive layer laminated on each of the above substrates. Examples of sensors include touch sensors. A touch sensor is a sensor that detects touch input when a finger, a touch pen, or other object approaches or touches the substrate, and is composed of a conductive layer laminated on the above substrate. When a finger, a touch pen, or other object approaches or touches the substrate, an electrical change such as capacitance, current, or voltage occurs in the conductive layer, and the touch sensor detects the touch input based on this electrical change. The conductive layer is not particularly limited, and any conventionally known transparent electrode material can be used without particular limitation. Examples include an indium tin oxide (ITO) conductive film, a tin oxide conductive film, a zinc oxide conductive film, and a polymer conductive film. Furthermore, an organic material substrate (particularly a film) on which a conductive layer such as an electrode or a sensor is laminated may have the above-mentioned hard coat layer formed on the surface opposite to the surface on which the conductive layer is provided.

[0076] The laminate can also be used to make a display. For example, a laminate including a display element, an intermediate film, and a surface protection panel can be used as a display. Furthermore, a touch panel can be provided on the display to make a display with a touch panel. An example of a touch panel display is a laminate including a display element, an intermediate film, a touch panel, an intermediate film, and a surface protection panel in this order. The respective components are adhered and joined by the intermediate film.

[0077] The surface protection panel is preferably either an organic resin plate or an inorganic glass plate, but is preferably an inorganic glass plate. The surface protection panel may be an OGS (one glass solution) panel, and may be provided with a sensor such as a touch sensor. Therefore, the surface protection panel may be composed of an inorganic glass plate equipped with a sensor.

[0078] Examples of the display element include an organic EL display element and a liquid crystal display element. The display element preferably has a polarizing plate (polarizing film) provided on its surface. The polarizing plate (polarizing film) generally has a configuration in which protective films are provided on both sides of a polarizer such as a polyvinyl alcohol resin film. The protective film is made of the above-mentioned resin film for substrate, and is preferably any one of a PET film, a COP film, or a TAC film. Note that a hard coat layer made of a (meth)acrylic resin or the like may be provided on the surface of the protective film as a surface layer of the substrate.

[0079] The touch panel may be composed of inorganic glass, an organic resin plate, or a substrate resin film to which a touch sensor is attached, but inorganic glass or a substrate resin film to which a touch sensor is attached is preferred. Furthermore, in the touch panel, the inorganic glass, the organic resin plate, or the substrate resin film may be a multilayer structure in which two or more of these are laminated. Even in this case, the touch panel may have a touch sensor attached to either the inorganic glass, the organic resin plate, or the substrate resin film. Furthermore, the touch panel may have a protective film made of a substrate resin film disposed on either the outermost surface on the front side or the outermost surface on the back side. Therefore, the adhesive surface of the touch panel to the interlayer film is either inorganic glass, organic glass, or a substrate resin film.

[0080] The laminate can also be used to form a solar cell. An example of a solar cell including the laminate is a solar cell in which a power generating cell is provided on the laminate. The power generating cell is provided on the surface or side of the laminate and has the function of converting light into electricity. Specific examples of the power generating cell include power generating cells using silicon-based semiconductors such as single crystal silicon, polycrystalline silicon, and amorphous silicon as a photoelectric conversion layer, power generating cells using compound-based semiconductors such as CuInSe, Cu(In,Ga)Se, Ag(In,Ga)Se, CuInS, Cu(In,Ga)S, Ag(In,Ga)S, and solid solutions thereof, CIS, CIGS, GaAs, and CdTe as a photoelectric conversion layer, and organic power generating cells using organic materials such as organic dyes as a photoelectric conversion layer.

[0081] (Method for manufacturing laminate and laminated glass) The laminate of the present invention can be manufactured, for example, by preparing a pair of substrates and one or more interlayer films, disposing one interlayer film or multiple overlapping interlayer films between the pair of substrates, and bonding them together under pressure. The method of bonding is not particularly limited, but it is preferable to bond them under pressure while heating. Alternatively, after pre-bonding at a relatively low pressure and temperature, the pressure, temperature, or both may be increased to higher levels than those for pre-bonding. When multiple interlayer films are disposed between the pair of substrates, it is preferable to integrate the multiple interlayer films during bonding under pressure.

[0082] Furthermore, when the laminate is a laminated glass, for example, one or more interlayer films are sandwiched between two glass members and passed through a pressure roll, or placed in a rubber bag and subjected to vacuum suction to remove any air remaining between the two glass members and the interlayer films. This is then pre-bonded at approximately 70 to 110°C to obtain a laminated intermediate. The laminated intermediate is then placed in an autoclave or pressed at approximately 120 to 150°C and a pressure of 1 to 1.5 MPa for full bonding. In this manner, laminated glass can be obtained. When multiple interlayer films are disposed between a pair of glass members, the multiple interlayer films are preferably integrated during the pre-bonding and full bonding processes.

[0083] The interlayer film, laminate, and laminated glass of the present invention can be used in a variety of fields, including electronic devices such as displays, solar cells, solar cell encapsulants, vehicles such as automobiles, railway cars, aircraft, and ships, and various architectural structures such as buildings, condominiums, detached houses, halls, and gymnasiums. Among these, their use in vehicles and architectural structures is preferred, and their use in architectural structures is particularly preferred. In vehicles and architectural structures, laminated glass is preferably used. In vehicle applications, it is preferably used as window glass, and in automobiles, for example, it is preferably used as any of the windshield, rear glass, and side glass. In architectural structures, it is preferably used as window glass, glass floors, curtain walls, and the like. When used in architectural structures, the laminated glass may be, for example, enlarged and used as structural glazing.

[0084] The present invention will be explained in more detail by way of examples, but the present invention is not limited to these examples in any way.

[0085] The measurements and evaluations of various physical properties were carried out as follows.

[0086] [Thickness of Interlayer Film] The thickness of the interlayer film was measured as an average of 10 points using a microscope "DSX500" manufactured by Olympus Corporation.

[0087] [Content and Degree of Neutralization of Each Structural Unit] The mass % of each structural unit of an ethylene / (meth)acrylic acid copolymer and its ionomer resin was determined by the following hydrochloric acid treatment: １ H-NMR and IR measurements were carried out to determine the content. [Hydrochloric acid treatment] 500 μL of ethanol and 1 mL of hydrochloric acid were added to 100 mg of a sample that had been freeze-pulverized using a JFC-2000 (manufactured by Japan Analytical Industry Co., Ltd.), and the mixture was stirred at 60°C for 48 hours. The mixture was then washed three times with ultrapure water to remove the hydrochloric acid, and dried by heating.

[0088] [Degree of Neutralization] The degree of neutralization was determined by IR measurement of a sample before and after hydrochloric acid treatment. －１Based on the methylene peak height of 1700 cm －１ The carboxylic acid peak height was calculated using the following formula: In the following formula, the denominator is the peak height of 1700 cm for the sample after the hydrochloric acid treatment. －１ Peak height / 1460 cm －１ The peak height of the molecule is 1700 cm for the sample before hydrochloric acid treatment. －１ Peak height / 1460 cm －１ represents the peak height of [ １ H-NMR Measurement] The sample after the hydrochloric acid treatment was dissolved in a solvent (tetrachloroethane:dimethyl sulfoxide = 5:2) to a concentration of about 1 to 3 wt % to prepare a measurement solution. １ H-NMR measurement (apparatus: AVANCE 400 (PRODIGY), spectrometer: AVANCE III HD) was carried out. The measurement conditions were an accumulation of 8 times and a temperature of 120°C. In the analysis, the integrated value of H derived from the methyl group of methacrylic acid was used as the reference, and this value was set to 3.00. At that time, the total mass% of the structural units (A) and (B) and the mass% content of the ethylene-derived structural unit (C) were calculated from the integrated intensity ratio of the H peak derived from methylene appearing at 1.15-1.62 ppm. Furthermore, the respective contents of the structural units (A) and (B) were calculated from the above-mentioned degree of neutralization.

[0089] [Yellowness Index (YI)] The YI value (yellowness index) of the obtained laminated glass was measured by a transmission method using a spectrophotometer (Hitachi High-Technologies Corporation, model U-4100) in accordance with JIS K7105.

[0090] [λ1-λ2] (1) Preparation of Laminated Glass Two sheets of clear glass (5 cm long x 5 cm wide x 2.5 mm thick, visible light transmittance 90.4%, manufactured by Central Glass Co., Ltd.) conforming to JIS R3202 (2011) and a 5 cm x 5 cm interlayer film prepared in each of the Examples and Comparative Examples were prepared, and the interlayer film was sandwiched between the two sheets of clear glass to obtain a laminate. This laminate was placed in a rubber bag and degassed for 20 minutes at a vacuum of 0.08 MPa. After that, it was transferred to an oven while degassed and further held at 90 ° C for 30 minutes to vacuum press the laminate, thereby temporarily bonding the laminate. The temporarily bonded laminate was then bonded for 20 minutes in an autoclave at 140 ° C and a pressure of 1.3 MPa to obtain a laminated glass consisting of a glass plate / interlayer film / glass plate.

[0091] (2) Measurement of λ1 (nm) For the laminated glass prepared as described above, transmittance was measured in the wavelength range of 300 to 460 nm using a spectrophotometer (Hitachi High-Technologies Corporation, "U-4100"). Then, in the region where light transmittance is 10% or more, the minimum wavelength λ1 (nm) at which the increase in transmittance (%) per increase in wavelength (nm) is 1 or less was determined. Specifically, in the region where light transmittance is 10% or more, the slope (increase in transmittance / increase in wavelength) between adjacent measurement points from the short wavelength side was calculated sequentially, and the portion where the slope first became 1 or less was identified. Then, when the adjacent measurement points where the slope first became 1 or less were designated as λn (nm) and λm (nm), the wavelength at the midpoint between λn (nm) and λm (nm) was designated as λ1 (nm).

[0092] (3) Measurement of λ2 (nm) For the UV absorbers used in each Example and Comparative Example, solutions were prepared at the same concentration (mass %) as in the interlayer film. Specifically, the UV absorbers were dissolved in either THF or triethylene glycol bis(2-ethylhexanoate) (3GO) to prepare the solutions. The solutions prepared as described above were introduced into a cell with an optical path length of 1 mm, and transmittance measurements were performed in the wavelength range of 300 to 460 nm using a spectrophotometer (Hitachi High-Tech Corporation, "U-4100"). The minimum wavelength λ2 (nm) at which the increase in transmittance (%) per increase in wavelength (nm) was 1 or less in the range of light transmittance of 10% or more was determined. Specifically, in the range of light transmittance of 10% or more, the slope (increase in transmittance / increase in wavelength) between adjacent measurement points, starting from the shortest wavelength, was calculated sequentially, and the point where the slope first became 1 or less was identified. Then, when the adjacent measurement points where the slope first became less than 1 were defined as λn (nm) and λm (nm), the wavelength at the midpoint between λn (nm) and λm (nm) was defined as λ2 (nm).

[0093] [Transmittance at wavelengths of 380 nm and 420 nm] Two sheets of clear glass (5 cm long x 5 cm wide x 2.5 mm thick, visible light transmittance 90.4%, manufactured by Central Glass Co., Ltd.) conforming to JIS R3202 (2011) and an interlayer film prepared in each of the examples and comparative examples measuring 5 cm x 5 cm were prepared, and the interlayer film was sandwiched between the two sheets of clear glass to obtain a laminate. This laminate was placed in a rubber bag and degassed at a vacuum of 0.08 MPa for 20 minutes, then transferred to an oven while degassed, and further held at 90 ° C for 30 minutes to vacuum press the laminate to pre-press the laminate. The pre-pressed laminate was pressed in an autoclave at 140 ° C and a pressure of 1.3 MPa for 20 minutes to obtain a laminated glass consisting of a glass plate / interlayer film / glass plate. The laminated glass prepared as described above was measured for transmittance at a wavelength of 380 nm (T380) and transmittance at a wavelength of 420 nm (T420) using a spectrophotometer (Hitachi High-Technologies Corporation's "U-4100").

[0094] [Evaluation of Yellowing Suppression] The interlayer films produced in each Example and Comparative Example were used as samples. The samples were cut into 5 cm squares and fixed upright on a stand. The edge of the sample was observed from the front, and the yellowness was compared with that of a color sample (yellowness index 0.5) and evaluated by 10 evaluators. The yellowing suppression evaluation was performed according to the following criteria: A: 3 or less out of 10 people rated it as more yellow than the color sample; B: 4 to 5 out of 10 people rated it as more yellow than the color sample; C: 6 or more out of 10 people rated it as more yellow than the color sample.

[0095] [Evaluation of Adhesion] (Production of Laminated Glass) The interlayer films according to Examples 5 to 7 described below were subjected to a pummel test. The interlayer films according to Examples 5 to 7 were sandwiched between two 2.5 mm-thick clear glass sheets (300 mm long x 300 mm wide) conforming to JIS R3202 (2011) to obtain laminates. Top-face-attached laminates were prepared by laminating the top surface of the interlayer film in contact with the interlayer film, and bottom-face-attached laminates were prepared by laminating the bottom surface of the interlayer film in contact with the interlayer film. The laminates were placed in a rubber bag and degassed at a vacuum of 0.08 MPa for 20 minutes. Then, the degassed laminates were transferred to an oven and held at 90°C for 30 minutes for vacuum pressing to temporarily bond the laminates. The temporarily bonded laminates were then pressed in an autoclave at 140°C and a pressure of 1.3 MPa for 20 minutes to obtain laminated glass consisting of a glass plate / interlayer film / glass plate.

[0096] (Pummel Test) The obtained laminated glass was left to stand for 16 hours in a temperature environment of 23°C ± 0.6°C. After standing, the central portion of the laminated glass (a portion measuring 150 mm long x 150 mm wide) was struck with a hammer with a head of 0.45 kg to crush the glass particles to a particle size of 6 mm or less. The other side was also struck with the hammer the same number of times. The degree of film exposure after partial glass peeling was measured, and the pummel value was calculated according to Table 1 below. For each example, measurements were performed on two sheets of laminated glass, and the average value was calculated by arithmetically averaging the four pummel values ​​obtained from the measurements on the front and back surfaces. The pummel value is a value used to measure the degree of adhesion between the interlayer film and the glass sheet, and is a value defined by the degree of film exposure (area %) after partial glass peeling, as defined in Table 1. A higher pummel value indicates higher adhesion of the interlayer film.

[0097]

[0098] The components used in the examples and comparative examples are as follows.

[0099] <Ionomer Resin> Details of the ionomer resin are as follows. *Ionomer resin 1 is an ionomer resin made by neutralizing an ethylene-methacrylic acid copolymer with magnesium ions.

[0100] <Ultraviolet absorbers> Compound having a benzotriazole structure represented by formula (I): "RIASORB UV-234" manufactured by Rianlon, a compound represented by formula (2), shown as "UV-234" in Table 3. Compound having a benzotriazole structure represented by formula (I): "Tinuvin 640" manufactured by BASF, a compound represented by formula (3), shown as "UV-640" in Table 3. Compound having a triazine structure: "UV-1164" manufactured by Rianlon, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol, shown as "UV-1164" in Table 3. Benzophenone-based ultraviolet absorber, "SEESORB 107" manufactured by Shipro Chemical Co., Ltd. Compound having a benzotriazole structure not corresponding to formula (I): "Tinuvin-P" manufactured by BASF

[0101] [Example 1] (Preparation of interlayer film) 100 parts by mass of ionomer resin 1 and 0.3 parts by mass of an ultraviolet absorber were kneaded at 170°C and extruded to obtain an interlayer film having a thickness of 1000 µm and the composition shown in Table 3. Various evaluations were performed on the interlayer film.

[0102] [Examples 2 to 4, Comparative Examples 1 to 3] Interlayer films were produced in the same manner as in Example 1, except that the composition of the resulting interlayer film was changed as shown in Table 3. Various evaluations were carried out on the resulting interlayer film.

[0103] [Example 5] An interlayer film was produced in the same manner as in Example 1, except that the type of ultraviolet absorber was changed to those shown in Table 4, the content was changed to 0.2 parts by mass, and the interlayer film thickness was changed to 760 μm. Various evaluations were performed on the interlayer film.

[0104] Example 6 An interlayer film was prepared in the same manner as in Example 5, except that 3-glycidoxypropylmethyldimethoxysilane (manufactured by Shin-Etsu Silicones Co., Ltd., product name: KBE-402) was added as a silane coupling agent so that the amount was 0.1 wt % when the entire interlayer film was taken as 100 mass %. Various evaluations were performed on the interlayer film.

[0105] Example 7 An interlayer film was prepared in the same manner as in Example 5, except that N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (manufactured by Shin-Etsu Silicones Co., Ltd., product name: KBM-602) was added as a silane coupling agent so that the amount was 0.1 wt %, taking the entire interlayer film as 100 mass %. Various evaluations were performed on the interlayer film. The results of Examples 5 to 7 are shown in Table 4.

[0106]

[0107]

[0108] The interlayer films of each Example contained an ultraviolet absorber, had low T380 (%) values, and exhibited good ultraviolet shielding performance. Furthermore, despite containing an ionomer resin, they had low yellowness index (YI) and suppressed discoloration. Furthermore, the results of Examples 5 to 7 demonstrate that interlayer films containing an ionomer resin and a silane coupling agent can exhibit excellent adhesion regardless of the glass surface. The interlayer film of Comparative Example 1 did not contain an ultraviolet absorber and exhibited low yellowness index, but had a high T380 (%) value and poor ultraviolet shielding performance. The interlayer films of Comparative Examples 2 and 3 did not use the specific ultraviolet absorber of the present invention, had high yellowness index (YI), and were found to be more susceptible to discoloration than the interlayer films of the Examples.

Claims

1. An interlayer film containing an ionomer resin and an ultraviolet absorber, wherein the ultraviolet absorber is at least one selected from the group consisting of compounds having a benzotriazole structure and compounds having a triazine structure represented by the following formula (I). (In the above formula, R １ is an organic group having 4 or more carbon atoms, R ２ ~R ８ are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.

2. The interlayer film according to claim 1, wherein the compound having a benzotriazole structure is a compound represented by any one of the following formulas (2) to (4):

3. The interlayer film according to claim 1 or 2, wherein the content of the ultraviolet absorber is 0.01 to 1 part by mass per 100 parts by mass of the ionomer resin.

4. The interlayer film according to claim 1 or 2, wherein the ionomer resin contains at least one of magnesium and zinc.

5. The interlayer film according to claim 1 or 2, which contains a silane coupling agent.

6. The intermediate film according to claim 5, wherein the silane coupling agent is a silane coupling agent having an epoxy group.

7. The interlayer film according to claim 5, containing the silane coupling agent in an amount of 0.01% by mass or more and 0.5% by mass or less when the entire interlayer film is taken as 100% by mass.

8. A laminate comprising the interlayer film according to claim 1 or 2 and a pair of substrates, the interlayer film being disposed between the pair of substrates.

9. The laminate according to claim 8, which is a laminated glass.

10. The laminate according to claim 8, which is a laminated glass for architectural structures.

11. A method for producing an interlayer film according to claim 1 or 2, comprising the steps of: kneading a mixture of an ionomer resin, an ultraviolet absorber and an ethylene / (meth)acrylic acid copolymer to obtain a resin composition; and extruding the resin composition.

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