Interlayer film, laminate, and method for manufacturing an 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

[Technical Field]

[0001] This invention relates to an interlayer, a laminate, and a method for manufacturing an interlayer. [Background technology]

[0002] Laminated glass is safer because, even if it breaks due to external impact, the glass fragments are less likely to scatter. Therefore, it is widely used in windows of various vehicles such as automobiles, railway cars, aircraft, and ships, as well as in buildings. Laminated glass is generally known to consist of a pair of glass panes with an interlayer made of thermoplastic resin or similar material sandwiched between them. When used in buildings, laminated glass is used not only for windows but also for glass floors and curtain walls. In these applications, it is sometimes produced in large sizes and used as structural glazing.

[0003] Conventionally, ionomer resins are sometimes used as interlayers for laminated glass. Known ionomer resins used as interlayers 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 of the side chains are crosslinked between molecular chains by metal cations (see, for example, Patent Documents 1-3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2021 / 002326 [Patent Document 2] Japanese Patent Publication No. 2022-120218 [Patent Document 3] Japanese Patent Publication No. 2019-77582 [Overview of the project] [Problems that the invention aims to solve]

[0005] Generally, ionomer resins do not absorb ultraviolet light, so in order to reduce the ultraviolet transmittance of an interlayer containing ionomer resin, it is necessary to incorporate an ultraviolet absorber. Examples in Patent Documents 1 to 3 show cases in which an ultraviolet absorber is incorporated into ionomer resin.

[0006] However, our investigations have shown that adding an ultraviolet absorber to an interlayer containing an ionomer resin can cause the interlayer to become discolored, resulting in a decrease in aesthetic appeal. Therefore, the object of the present invention is to provide an interlayer containing an ionomer resin that suppresses ultraviolet light transmittance while exhibiting minimal discoloration. [Means for solving the problem]

[0007] As a result of diligent research, the inventors of the present invention have found that the above problems can be solved by an interlayer containing an ionomer resin and at least one ultraviolet absorber selected from the group consisting of compounds having a benzotriazole structure represented by the following formula (I) and compounds having a triazine structure, and have completed the present invention. The gist of this invention is as follows:

[0008] [1] An interlayer 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 represented by the following formula (I) and compounds having a triazine structure. [ka] (In the above formula, R1 is an organic group having 4 or more carbon atoms, and R2 to R8 are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.) [2] The intermediate film according to [1] above, wherein the compound having the benzotriazole structure is one of the compounds of formula (2) to (4) below. [ka] [3] The interfilm according to [1] or [2] above, 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 interfilm according to any one of [1] to [3] above, wherein the ionomer resin contains at least one of magnesium and zinc. [5] An intermediate film according to any of [1] to [4] above, comprising a silane coupling agent. [6] The intermediate film according to [5], wherein the silane coupling agent is a silane coupling agent having an epoxy group. [7] The interlayer 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 is considered as 100% by mass. [8] An interlayer film according to any of [1] to [7] above, used as a encapsulant for solar cells. [9] A resin composition comprising 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 represented by the following formula (I) and compounds having a triazine structure. [ka] (In the above formula, R1 is an organic group having 4 or more carbon atoms, and R2 to R8 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 [9] above, wherein the compound having the benzotriazole structure is one of the compounds of the following formulas (2) to (4). [ka]

[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 intermediate film according to any one of [1] to [8] above and a pair of base materials, wherein the intermediate film is disposed between the pair of base materials.

[13] The laminate according to

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

[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 architectural structures.

[16] A display including the laminate according to

[12] or

[13] above.

[17] A solar cell including the laminate according to

[12] or

[13] above.

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

[0009] According to the present invention, it is possible to provide an intermediate film with less coloring while suppressing the ultraviolet transmittance. [Brief Description of the Drawings]

[0010] [Figure 1] It is a diagram schematically explaining λ1-λ2 in the present invention.

[0011] [Intermediate Film] The intermediate film of the present invention contains an ionomer resin and an ultraviolet absorber, and the ultraviolet absorber is at least one intermediate film selected from the group consisting of a compound having a benzotriazole structure represented by the following formula (I) and a compound having a triazine structure.

[0012] [Ultraviolet Absorber] The intermediate film of the present invention contains an ultraviolet absorber. By containing an ultraviolet absorber, the ultraviolet shielding property of the intermediate film is improved. The ultraviolet absorber is at least one selected from the group consisting of compounds having a benzotriazole structure represented by the following formula (I) and compounds having a triazine structure. Including such a specific ultraviolet absorber makes it easier to suppress discoloration of the interlayer film. The reason for this is not entirely clear, but it is thought that by using an ultraviolet absorber with a specific structure, the metal ions contained in the ionomer resin become less likely to coordinate with the ultraviolet absorber, and as a result, discoloration of the interlayer is suppressed.

[0013] [ka] (In the above formula, R1 is an organic group having 4 or more carbon atoms, and R2 to R8 are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.)

[0014] In formula (I) above, R1 is an organic group with 4 or more carbon atoms. This makes it easier to suppress discoloration of the interlayer. The reason for this is not entirely clear, but it is presumed that R1 is the group in the ortho position of the hydroxyl group in formula (I), and because it is an organic group with 4 or more carbon atoms, it makes it easier to suppress coordination between the UV absorber and the metal present in the ionomer resin, and as a result, discoloration of the interlayer can be suppressed.

[0015] From the viewpoint of suppressing discoloration of the interlayer film, R1 is preferably an organic group having 4 to 20 carbon atoms, and more preferably an organic group having 4 to 10 carbon atoms. R1 may contain oxygen atoms, nitrogen atoms, sulfur atoms, etc., but is preferably a hydrocarbon group. In other words, R1 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. Furthermore, it is preferable that R1 comprises either a quaternary carbon atom or an aromatic ring, or both. It is presumed that having such a structure makes it easier to suppress the coordination between the UV absorber and the metal in the ionomer resin, and as a result, the discoloration of the interlayer can be further suppressed. R1 is particularly preferably a group represented by the following formula (a) or formula (b). [ka] In formulas (a) and (b), the asterisk (*) represents a bond that connects to the aromatic ring shown in formula (I).

[0016] In formula (I) above, R2 to R8 are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine, with chlorine being preferred. The organic group may contain oxygen atoms, nitrogen atoms, sulfur atoms, etc., or it may be a hydrocarbon group. In the above formula (I), R2, R4, R5, R6, R7, and R8 are each preferably independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylamino group, anilino group, an acylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, an alkylthio group, or an arylthio group, and among these, a hydrogen atom is more preferably.

[0017] In formula (I) above, R3 is a hydrogen atom or an organic group having 1 to 20 carbon atoms. The organic group may include an oxygen atom, a nitrogen atom, a sulfur atom, etc., or it may be a hydrocarbon group. From the viewpoint of suppressing discoloration of the interlayer film, R3 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 1 to 10 carbon atoms having an ester structure. Furthermore, it is preferable that the hydrocarbon group having 1 to 10 carbon atoms comprises either a quaternary carbon atom or an aromatic ring, or both. R3 is particularly preferably a group represented by the following formulas (c), (d), or (e). [ka] In formulas (c), (d), and (e), the asterisk (*) represents a bond that connects 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 the benzotriazole structure of formula (I), any of the compounds of formulas (2) to (4) below are preferred, and the compound of formula (2) or (3) is more preferred. [ka]

[0019] The types of compounds having a triazine structure are 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-triazin-2-yl]-5-(octyloxy)phenol is preferred because it easily suppresses the discoloration of the interlayer.

[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 performance of the interlayer, it is preferable that it be a compound having a benzotriazole structure represented by formula (I).

[0021] The amount of UV absorber in the interlayer 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, 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, per 100 parts by mass of ionomer resin. If the amount of UV absorber is above these lower limits, the UV shielding performance of the interlayer tends to improve further. On the other hand, if the amount of UV absorber is below these upper limits, discoloration of the interlayer tends to be suppressed more easily.

[0022] <Ionomer resin> The interlayer of the present invention contains an ionomer resin. Examples of ionomer resins include ionomer resins of ethylene-unsaturated carboxylic acid copolymers. Typically, ionomer resins are 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. Among these, acrylic acid and methacrylic acid are preferred. Therefore, the ionomer resin is preferably an ionomer resin of an ethylene-(meth)acrylic acid copolymer. Furthermore, examples of metal ions include lithium, potassium, sodium, silver, copper, calcium, magnesium, titanium, zinc, aluminum, barium, beryllium, strontium, tin, lead, iron, cobalt, nickel, cadmium, and mercury, but among these, at least one of magnesium and zinc is preferred. A single metal ion may be used, or two or more may be used in combination. If the ionomer resin contains at least one of magnesium and zinc, and particularly magnesium, The formation of an appropriate cross-linking structure makes it easier to raise the glass transition temperature of the interlayer and thus increase its rigidity. On the other hand, the inventors have found that when magnesium is the metal ion used in the ionomer, the interlayer film tends to become discolored. As in the present invention, by using a specific ultraviolet absorber, discoloration can be suppressed even when using an ionomer resin that is prone to discoloration. Note that (meth)acrylic acid means at least one of methacrylic acid or acrylic acid, and the same applies to the following similar terms.

[0023] When an ionomer resin is an ionomer resin of an ethylene-unsaturated carboxylic acid copolymer, it typically contains constituent units (A) derived from an unsaturated carboxylic acid, constituent units (B) derived from an unsaturated carboxylic acid neutralized product, and constituent units (C) derived from ethylene. In the case of an ionomer resin made of ethylene-(meth)acrylic acid copolymer, it typically contains constituent units derived from (meth)acrylic acid (constituent unit (A)), constituent units derived from (meth)acrylic acid neutralized product (constituent unit (B)), and constituent units derived from ethylene (constituent unit (C)). The inclusion of these constituent units (A), (B), and (C) in the ionomer resin makes it easier to increase its rigidity.

[0024] The monomer constituting the constituent unit (A) is not particularly limited as long as it is an unsaturated carboxylic acid, but it is preferably at least one of acrylic acid and methacrylic acid, and more preferably methacrylic acid from the viewpoint of rigidity and adhesiveness. Note that constituent unit (A) is a constituent unit that has not been neutralized by metal ions. The constituent unit (B) is a neutralized product of the constituent unit derived from the unsaturated carboxylic acid, but it is preferably a neutralized product of a constituent unit derived from at least one of acrylic acid and methacrylic acid, and more preferably a constituent unit of methacrylic acid neutralized product. The constituent unit (B) is preferably a neutralized unit of the constituent unit (A) above. Constituent unit (B) is a constituent unit obtained by substituting the hydrogen ions of the carboxyl group in an unsaturated carboxylic acid with metal ions. That is, the unsaturated carboxylic acid neutralized product in constituent unit (B) is a metal salt of the unsaturated carboxylic acid. The metal ions in the metal salt are as described above, but at least one of magnesium and zinc is preferred, and magnesium is particularly preferred. Therefore, the constituent unit (B) preferably contains at least one of magnesium and zinc, and is particularly preferably magnesium.

[0025] In ionomer resins, the total content of constituent units (A) and (B) is preferably 10% by mass or more and 25% by mass or less, based on the total amount of constituent units constituting the ionomer resin. When the total content of constituent units (A) and (B) is 10% by mass or more, the transparency, heat resistance, and mechanical strength of the interlayer can be improved. Furthermore, when it is 25% by mass or less, flexibility, processability, and adhesion can be improved. More preferably, the total content of constituent units (A) and (B) is 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 ionomer resins, the content of constituent unit (B) is preferably 4% by mass or more and 18% by mass or less, based on the total amount of constituent units constituting the ionomer resin. When the content of constituent unit (B) is 4% by mass or more, the degree of crosslinking of the ionomer resin increases, making it easier to increase its rigidity. Furthermore, when it is 4% by mass or more, it is easier to increase transparency and heat resistance. In addition, by setting the content of constituent unit (B) to 18% by mass or less, it is easier to improve the flexibility, adhesion, mechanical strength, and processability of the interlayer film. The content of constituent 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] From the viewpoint of easily improving the impact resistance of the ionomer resin, the content of ethylene-derived constituent units (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 constituent units constituting the ionomer resin. Furthermore, from the viewpoint of transparency, mechanical strength, and moldability, the content of ethylene-derived constituent units (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 constituent unit (A) is not particularly limited, but it is preferably 3% by mass or more and 10% by mass or less based on the total amount of constituent units constituting the ionomer resin, more preferably 4% by mass or more and 9% by mass or less, and even more preferably 8% by mass or less.

[0029] In ionomer resins, constituent units other than constituent units (A), (B), and (C) (hereinafter also referred to as "other constituent units") may be contained. Therefore, the ionomer resin may be a copolymer obtained by copolymerizing ethylene and an unsaturated carboxylic acid and neutralizing it with metal ions, or a copolymer obtained by copolymerizing ethylene, an unsaturated carboxylic acid, and monomers other than ethylene and an unsaturated carboxylic acid and neutralizing it with metal ions. Other constituent units include constituent unit (D) derived from alkyl (meth)acrylate. The presence of constituent unit (D) allows for adjustment of the glass transition temperature (Tg) of, for example, ionomer resins. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl, which have approximately 1 to 10 carbon atoms. From the viewpoint of not lowering the glass transition temperature unnecessarily, the content of constituent units (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. Furthermore, from the viewpoint of increasing rigidity without lowering the glass transition temperature, the less the content of constituent units (D), it is preferable to have 0% by mass or more, and it is preferable that the ionomer resin does not contain constituent units (D).

[0030] Furthermore, while isobutyl (meth)acrylate is generally preferred as the alkyl (meth)acrylate in ionomer resins, in the present invention, it is preferable that the ionomer resin does not contain any constituent units derived from isobutyl (meth)acrylate, or contains only a small amount. Therefore, the content of constituent 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. In addition, the content of constituent 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 constituent units derived from isobutyl (meth)acrylate.

[0031] Furthermore, the ionomer resin may contain other constituent units besides constituent units (A), (B), (C), and (D), for example, constituent 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, but from the viewpoint of increasing rigidity, it is preferable to exceed 40%, more preferably 42% or more, even more preferably 45% or more, and even more preferably 50% or more. Furthermore, in this invention, by including at least one of magnesium and zinc (especially magnesium) in the constituent unit (B) and increasing the degree of neutralization, it becomes easier to further improve rigidity. Furthermore, while the degree of neutralization of the ionomer resin is not particularly limited, from the viewpoint of improving the flexibility, adhesion, mechanical strength, and processability 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 all carboxyl groups contained in the ionomer resin that are neutralized by metal ions.

[0033] The degree of neutralization in the above-mentioned ionomer resin can be determined from IR measurements before and after hydrochloric acid treatment. The specific measurement method is as described in the examples below. Furthermore, the content of each constituent unit in the above ionomer resin was determined by mass spectrometry and 1 This can be calculated by performing 1H-NMR measurements and determining the degree of neutralization from the integrated intensity ratio of the hydrogen peaks originating from each monomer.

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

[0035] The ionomer resin content in the interlayer 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, when the entire interlayer is considered to be 100% by mass. By setting the ionomer resin content to the above lower limit, the rigidity and interlayer adhesion of the resulting laminated glass can be improved. Furthermore, the ionomer resin content in the interlayer should be 100% by mass or less when the entire interlayer is considered to be 100% by mass. 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. Furthermore, if the ionomer resin in the interlayer contains other resin components as described later, the content of the ionomer resin in the interlayer should be kept below a certain amount, for example, it may be 98% by mass or less, or 97% by mass or less.

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

[0037] <Other resin components> The interlayer of the present invention may contain other resin components in addition to the ionomer resin described above. The ionomer resin may become too viscous during kneading, reducing its extrudeability, but the interlayer of the present invention, by containing other resin components, has good extrudeability. The other resin component is preferably a resin that is compatible with the ionomer resin. From the viewpoint of compatibility with the ionomer resin, an ethylene-unsaturated carboxylic acid copolymer is preferred as the other resin component. Here, the unsaturated carboxylic acid used in the ethylene-unsaturated carboxylic acid copolymer is as described above, and among them, (meth)acrylic acid is preferred, and methacrylic acid is more preferred. Furthermore, from the viewpoint of compatibility and extrudeability, it is preferable to use the same type of copolymer as the copolymer used in the above-mentioned ionomer resin for the other resins, and it is even more preferable to use the resin before it is neutralized with metal ions to obtain the above-mentioned ionomer resin. Therefore, if the ionomer resin is an ionomer resin of an ethylene-(meth)acrylic acid copolymer, it is preferable that the other resins are also ethylene-(meth)acrylic acid copolymers. Also, if the ionomer resin is an ionomer resin of an ethylene-methacrylic acid copolymer, it is preferable that the other resins are also ethylene-methacrylic acid copolymers.

[0038] When other resin components are used, the content of these other resin components is preferably 1.5% by mass or more and 25% by mass or less, based on 100% by mass of the entire interlayer. By setting the content of other resin components to 2% by mass or more, the viscosity of the ionomer resin is reduced, making it easier to improve extrudeability. Furthermore, by setting it to 25% by mass or less, it is possible to prevent a decrease in rigidity even when other resin components are included. The content of 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, based on 100% by mass of the entire interlayer.

[0039] <Silane coupling agent> The interlayer may contain a silane coupling agent as an additive. The inclusion of a silane coupling agent in the interlayer makes it easier to improve adhesion to the substrate, glass, etc. The inventors have found that an interlayer containing ionomer resin has different glass adhesion properties than an interlayer containing polyvinyl acetal resin. Specifically, they found that the interlayer containing ionomer resin exhibits lower adhesion to the top surface of float glass compared to its adhesion to the bottom surface. Further investigation revealed that by adding a silane coupling agent to the interlayer containing ionomer resin, excellent adhesion can be achieved regardless of the glass surface. Examples of the silane coupling agents mentioned above include those having a polymerizable carbon-carbon double bond, such as a vinyl group or (meth)acryloyl group, a functional group such as an amino group or epoxy group, and a hydrolyzing group such as an alkoxy group.

[0040] Examples of silane coupling agents having polymerizable carbon-carbon double bonds 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 containing 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 hydrochloride salts of N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane. 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 may contain one silane coupling agent alone, or it may contain two or more silane coupling agents.

[0041] Among these, silane coupling agents having an amino group are preferred from the viewpoint of improving adhesion to glass and substrates, and among them, 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 the glass and substrate and further reducing the yellowness of the interlayer film, it is more preferable to use a silane coupling agent having an epoxy group, and among these, 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane are even more preferable.

[0042] From the viewpoint of improving adhesion to glass and substrates, the content of the silane coupling agent in the interlayer is preferably 0.001% to 5% by mass, more preferably 0.005% to 2% by mass, even more preferably 0.01% to 1% by mass, even more preferably 0.01% to 0.5% by mass, and even more preferably 0.05% to 0.5% by mass, when the entire interlayer is considered as 100% by mass. Furthermore, although there is no particular upper limit, the content of the silane coupling agent is preferably 0.5% by mass or less, and 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 UV absorber and silane coupling agent mentioned above, the intermediate film may also contain at least one of the following additives: an antioxidant and other known additives.

[0044] Examples of antioxidants include phenolic compounds, phosphate compounds, and sulfur compounds. Antioxidants can prevent oxidative degradation of the interlayer film, thereby improving durability. Antioxidants may be used individually or in combination of two or more types.

[0045] The interlayer film of the present invention may contain other additives besides those listed above, such as plasticizers, light stabilizers, antistatic agents, surfactants, colorants, foaming agents, lubricants, crystal nucleating agents, crystallization accelerators, crystallization retarders, catalyst deactivators, heat absorbers, heat reflectors, heat dissipators, inorganic fillers, organic fillers, impact resistance modifiers, 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, dispersants, and the like.

[0046] <Difference between λ1 and λ2 (λ1-λ2)> The interlayer of the present invention is preferably an interlayer in which the difference between wavelengths λ1 (nm) and λ2 (nm), as described below (λ1-λ2), is 20 nm or less. The above wavelength λ1 is the smallest wavelength (nm) in the 300-460 nm wavelength range, in the region where the light transmittance is 10% or more, where the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less, in the transmittance measurement of laminated glass obtained by sandwiching an interlayer between two 2.5 mm thick clear glass sheets. The above wavelength λ2 is the smallest wavelength (nm) in the wavelength range of 300 to 460 nm, in the region where the light transmittance is 1 or less in proportion to the increase in wavelength (nm), when a solution of ultraviolet absorber with the same concentration (mass%) as the ultraviolet absorber contained in the interlayer is prepared and the transmittance measurement is performed on the solution under the conditions of an optical path length L (mm) defined by the following criteria. If the thickness of the interlayer is greater than 0 mm and less than 1.5 mm, the optical path length L shall be 1 mm; if the thickness of the interlayer is 1.5 mm or more and less than 2.5 mm, the optical path length L shall be 2 mm; if the thickness of the interlayer is 2.5 mm or more and less than 3.5 mm, the optical path length L shall be 3 mm; and if the thickness of the interlayer is 3.5 mm or more, the optical path length L shall be the length obtained by rounding the thickness of the interlayer (mm) to the first decimal place.

[0047] In the present invention, it is preferable that the difference between λ1 and λ2 (λ1-λ2) is 20 nm or less. When the difference between λ1 and λ2 is 20 nm or less, discoloration of the interlayer is easily suppressed, resulting in good aesthetics. From the viewpoint of further suppressing the discoloration of the interlayer, 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 UV absorber and ionomer resin used. The reason why the coloration of the interlayer can be suppressed when the difference between λ1 and λ2 is below a certain level is presumed to be as follows.

[0048] Figure 1 schematically shows the transmittance curve (dotted line) obtained by measuring the transmittance of laminated glass with an interlayer to calculate λ1, and the transmittance curve (solid line) obtained by measuring the transmittance of a solution to calculate λ2. The interlayer contains an ionomer resin and a UV absorber, whereas the solution contains the same concentration of UV absorber as the interlayer but does not contain the ionomer resin. The transmittance curve of the interlayer (dotted line) is shifted to longer wavelengths than the transmittance curve of the solution (solid line). This is presumed to be due to the coordination of metal ions contained in the ionomer resin in the interlayer with the ultraviolet absorber. This coordination of metal ions with the ultraviolet absorber is thought to be the cause of the interlayer's discoloration. Therefore, it is thought that discoloration of the interlayer can be suppressed when the shift to longer wavelengths is small, that is, when the difference between λ1 and λ2 is below a certain level.

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

[0050] In the transmittance measurement of laminated glass with an interlayer, 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 shielding performance of the interlayer 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 the transmittance measurement of laminated glass with an interlayer, it is preferable that the light transmittance at a wavelength of 420 nm is 80% or higher. When the light transmittance at a wavelength of 420 nm is 80% or higher, the transparency of the interlayer is improved and yellowing is further suppressed. It is more preferable that the light transmittance at a wavelength of 420 nm is 82% or higher, and even more preferable that it is 84% ​​or higher. The upper limit for the light transmittance at a wavelength of 420 nm is 100%.

[0051] In measuring the transmittance of laminated glass having the above-described interlayer, it is preferable that the light transmittance at wavelength λ1 is 80% or higher. More preferably, the light transmittance at λ1 is 82% or higher, and even more preferably 84% or higher. The upper limit of the light transmittance at λ1 is 100%.

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

[0053] Next, we will explain how to calculate λ1 and λ2. λ1 is the smallest wavelength (nm) in the wavelength range of 300 to 460 nm, in which the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less, in the region where the light transmittance is 10% or more, when measuring the transmittance of laminated glass obtained by sandwiching an interlayer between two 2.5 mm thick clear glass sheets. Here, the region where the light transmittance is 10% or more is the region to the right of point P on the transmittance curve (dotted line) of the interlayer in Figure 1, on the longer wavelength side. Also, the increase in transmittance (%) with respect to the increase in wavelength (nm) corresponds to the slope of the transmittance curve (dotted line), and the smallest wavelength at which this slope becomes 1 or less is λ1.

[0054] λ2 is determined by preparing a solution of ultraviolet absorber at the same concentration (mass%) as the ultraviolet absorber contained in the interlayer and measuring it. λ2 is the smallest wavelength (nm) in the wavelength range of 300 to 460 nm, where the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less, in a transmittance measurement performed under the condition of an optical path length L (mm) for the said solution, in the region where the light transmittance is 10% or more. Here, the region where the light transmittance is 10% or more is the region to the right of point Q on the transmittance curve of the solution (solid line) in Figure 1, on the longer wavelength side. Also, the increase in transmittance (%) with respect to the increase in wavelength (nm) corresponds to the slope of the transmittance curve (dotted line), and the smallest wavelength at which this slope is 1 or less is λ2.

[0055] The smallest wavelength at which the slope is less than or equal to 1 can be determined as follows: A transmittance curve is generally obtained by scanning the spectrum from short wavelengths to long wavelengths at equal intervals (e.g., 5 nm intervals) using a spectrophotometer and plotting the transmittance at each measurement point. If adjacent measurement points are denoted as λn(nm) and λm(nm), and the transmittance at λn(nm) is Tn(%) and the transmittance at λm(nm) is Tm(%), then 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 point where the slope first becomes 1 or less is identified. If the above-mentioned λn(nm) and λm(nm) points are the point where the slope first becomes 1 or less, then the wavelength at the midpoint between λn(nm) and λm(nm) will be λ1 or λ2.

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

[0057] Furthermore, the optical path length L used when measuring λ2 must be close to the thickness of the interlayer. Specifically, if the thickness of the interlayer is greater than 0 mm but less than 1.5 mm, the optical path length L should be 1 mm; if the thickness of the interlayer is 1.5 mm or more but less than 2.5 mm, the optical path length L should be 2 mm; if the thickness of the interlayer is 2.5 mm or more but less than 3.5 mm, the optical path length L should be 3 mm; and if the thickness of the interlayer is 3.5 mm or more, the optical path length L should be the thickness of the interlayer rounded to the first decimal place. The optical path length L can be adjusted by the type of cell into which the solution is introduced when measuring λ2.

[0058] <Yellowness (YI)> From the viewpoint of improving aesthetics, the yellowness (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. Furthermore, the yellowness (YI / d) per unit thickness of the interlayer 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. Note that the yellowness (YI / d) per unit thickness of the interlayer is the value obtained by dividing the yellowness (YI) by the thickness of the interlayer (mm). The degree of yellowness 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 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. If the thickness of the interlayer is above these lower limits, the rigidity, adhesion, and penetration resistance of the interlayer when it is laminated into glass can be improved. If the thickness of the interlayer is below these upper limits, it becomes easier to ensure the transparency of the interlayer.

[0060] (width) The interlayer of the present invention preferably has a width of 1 m or more. Having a width of 1 m or more allows for suitable use in large-format laminated glass and laminated glass for building structures. While a width of 1 m or more may make industrial mass production difficult, incorporating resins other than ionomer resins, such as ethylene-methacrylic acid copolymers, into the interlayer can facilitate mass production. A width of 2 m or more is more preferable for the interlayer. Furthermore, while the interlayer is not particularly limited, from the viewpoint of improving productivity, a width of 5 m or less is preferable, and 4 m or less is more preferable.

[0061] Furthermore, the interlayer of the present invention is preferably an extruded product obtained by extrusion molding as described later. Being an extruded product makes it easy to mass-produce large interlayers with a width of 1 m or more, as described above. In addition, while the viscosity of extruded products can be high and productivity may decrease, productivity can be improved by incorporating resins other than ionomer resins, such as ethylene-methacrylic acid copolymers, into the interlayer.

[0062] The interlayer of the present invention is preferably composed of a single-layer film. The layers constituting the single-layer film may consist of a resin composition having the composition described above. That is, the layers constituting the single-layer film may consist of a resin composition containing an ionomer resin, an ultraviolet absorber, and, if necessary, appropriate additives. Furthermore, the interlayer of the present invention may be a multilayer film of two or more layers. The multilayer film may have an overall composition of the interlayer as described above for the interlayer, but it is preferable that the resin compositions constituting each layer have the composition described above for the interlayer. That is, each layer may consist of a resin composition containing an ionomer resin and an ultraviolet absorber, as described above for the interlayer, and optionally containing appropriate additives. In a multilayer film, the compositions of each layer may be different from or the same. Furthermore, in single-layer or multi-layer films, the content of ionomer resin, ultraviolet absorber, other resin components, and additives in the resin composition constituting each layer may be as described above. However, while the standard for the content of each component described above was based on 100% by mass of the interlayer, in the resin composition constituting each layer, the standard for the content of each component shall be 100% by mass of the resin composition instead of 100% by mass of the interlayer.

[0063] [Method for manufacturing interlayer films] The interlayer can be prepared by obtaining a resin composition for forming the interlayer and then molding the interlayer from the resin composition. The resin composition can be prepared by mixing components that constitute the interlayer, such as an ionomer resin, an ultraviolet absorber, and additives other than the ultraviolet absorber as needed, and then forming the resulting resin composition into a film by extrusion molding, press molding, roll molding, etc. The method for mixing the components to obtain the resin composition is not particularly limited, but a method of kneading using an extruder is preferred. Furthermore, if the interlayer consists of multiple layers, it is preferable to prepare resin compositions for forming each layer, form each layer into a film by extrusion molding, press molding, roll molding, etc., and then laminate the layers to obtain the interlayer. In this case, co-extrusion is preferable for extrusion molding. Of the above methods, the interlayer is preferably formed by extrusion molding. By employing extrusion molding, a wide interlayer can be efficiently manufactured.

[0064] In one embodiment, the present invention may produce an interlayer film using a so-called masterbatch. The masterbatch consists of a mixture (hereinafter sometimes referred to as mixture (A)) obtained by mixing an additive with a resin component, and the resin component can be at least one of an ionomer resin and other resin components other than ionomer resins. The resin component other than the ionomer resin is preferably one of the other resin components mentioned above, and more preferably an ethylene-(meth)acrylic acid copolymer. By using a masterbatch, the additive can be easily mixed with 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 possible to easily knead the resin composition in an extruder or the like. The additives contained in mixture (A) preferably include an ultraviolet absorber, but may also include silane coupling agents or other additives. The form of mixture (A) is not particularly limited, but it is typically in the form of particles such as pellets.

[0065] Even when using a masterbatch, it is preferable to form the interlayer by extrusion molding. Therefore, in a preferred embodiment, the method for producing the interlayer may include a 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 a step (2) of extruding the obtained resin composition. In step (1), the mixing ratio of mixture (A) to the ionomer resin (mixture (A) / ionomer resin) is preferably 2 / 98 or more and 30 / 70 or less by mass ratio, 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 keeping the mixing ratio within the above range, additives and other resin components such as ethylene-(meth)acrylic acid copolymers can be blended into the resin composition in appropriate amounts.

[0066] Furthermore, 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 keeping the total amount of additives in mixture (A) above the lower limit, an appropriate amount of additives can be incorporated into the resin composition without mixing other resin components, such as ethylene-(meth)acrylic acid copolymers, into the resin composition in excess of what is necessary. Furthermore, by keeping the amount of additives in mixture (A) below the upper limit, the additives can be properly dispersed in mixture (A).

[0067] The interlayer of the present invention is preferably used by being placed between a pair of substrates, and more preferably by being used in a laminate, as described later. Furthermore, the interlayer may be used to bond a pair of substrates together. The interlayer is particularly preferably a laminated glass interlayer used in laminated glass. Furthermore, the interlayer can be used in applications other than laminates, such as various encapsulating materials, and specifically, it can be used as a encapsulating material for solar cells.

[0068] <Resin composition> In the present invention, a resin composition containing an ionomer resin and an ultraviolet absorber is also provided, wherein the ultraviolet absorber is at least one selected from the group consisting of compounds having a benzotriazole structure represented by the above formula (I) and compounds having a triazine structure. Furthermore, it is preferable that the above resin composition is a resin composition obtained by kneading an ionomer resin with a mixture of an ultraviolet absorber and an ethylene-(meth)acrylic acid copolymer. The interfilm obtained from this resin composition can suppress discoloration while having ultraviolet shielding properties. The resin composition may contain other resin components and additives other than UV absorbers, as needed. The content of ionomer resin, UV absorber, other resin components, and each additive in the resin composition should be as described above. However, while the standard for the content of each component described above was based on 100% by mass of the interlayer, in the resin composition, the standard for the content of each component should be 100% by mass of the resin composition instead of 100% by mass of the interlayer.

[0069] <Laminate> The laminate according to the present invention comprises the above-described interlayer film and a pair of substrates, wherein the interlayer film is placed between the pair of substrates. In the laminate, the pair of substrates may be bonded together via the interlayer film. Furthermore, in the laminate, the interlayer film placed between the pair of substrates may be a single film, or multiple interlayer films may be placed between the pair of substrates. The multiple interlayer films may be integrated between the substrates, and the pair of substrates may be bonded together via the integrated multiple interlayer films. The interlayers placed between laminates may need to be thick, for example, when used in building structures. However, by using multiple interlayers, it becomes easier to make the thickness of the interlayers placed between the laminates relatively large.

[0070] In the laminate of the present invention, it is preferable to select a pair of substrates from the group consisting of organic material substrates and inorganic material substrates. Examples of organic material substrates include organic resin plates and resin films. In the following text, resin films used as substrates may be referred to as "substrate resin films." Organic resin plates are also called organic glass plates. While not particularly limited, examples of organic resin plates include polycarbonate plates, (meth)acrylic plates such as polymethyl methacrylate plates, polyester plates such as acrylonitrile styrene copolymer plates, acrylonitrile butadiene styrene copolymer plates, and polyethylene terephthalate plates, fluororesin 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 polyimide resin plates. Organic resin plates may be subjected to appropriate surface treatments. Of the above, polycarbonate sheets are preferred due to their excellent transparency and impact resistance, (meth)acrylic sheets are preferred due to their high transparency, excellent weather resistance and mechanical strength, and among these, polycarbonate sheets are more preferred. The thickness of the organic resin sheet is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.4 mm or more, and also preferably 5.0 mm or less, and even more preferably 3.0 mm or less.

[0071] The resin film for the base material is not particularly limited, but examples 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, triacetylcellulose (TAC) film, polyethersulfone (PES) resin film, and polyimide resin film. Among these, PET film is preferred. Furthermore, a surface layer, such as a hard coat layer made of (meth)acrylic resin, may be provided on the surface of the resin film for the base material. The resin film for the base material may consist of a single layer, or it may be made up of two or more layers laminated together. Furthermore, the organic material substrate may be a functional film containing the above-mentioned resin film for the substrate. A polarizing film (polarizing plate) is a preferred example of the functional film.

[0072] The thickness of the resin film or functional film used as the base material in the laminate is not particularly limited, but is preferably 30 μm or more, more preferably 50 μm or more, and also preferably 500 μm or less, and even more preferably 450 μm or less. While materials that are relatively thick, have low flexibility, and are generally not bendable are called organic resin sheets, materials that are relatively thin and generally bendable are generally called resin films, these are not clearly distinguished from each other. Among the above, the organic material substrate is preferably a polarizing film (polarizing plate), PET film, (meth)acrylic sheet, or polycarbonate sheet.

[0073] Examples of inorganic material substrates include inorganic glass plates. While the inorganic glass plates are not particularly limited, examples include clear glass, clear float glass, float plate glass, tempered glass, colored glass, polished plate glass, patterned glass, wired plate glass, reinforced plate glass, ultraviolet absorbing plate glass, infrared reflective plate glass, infrared absorbing plate glass, and green glass. The inorganic glass may undergo surface treatment. 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 also preferably 5.0 mm or less, and even more preferably 3.0 mm or less.

[0074] Here, it is also preferable that both of the pair of substrates be 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 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 be 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, and more preferably 0.7 mm or more and 3 mm or less. As described above, the interlayer placed between the pair of glass members may be one layer or multiple layers.

[0075] The organic or inorganic material substrate may have electrodes, sensors, etc., attached to it as appropriate. The electrodes are composed of conductive layers laminated onto each of the above substrates. One example of a sensor is a touch sensor. A touch sensor is a sensor that detects touch input when a finger, stylus, or other object approaches or comes into contact with a substrate, and is composed of a conductive layer laminated on the substrate. When a finger, stylus, or other object approaches or comes into contact with the substrate, an electrical change such as capacitance, current, or voltage occurs in the conductive layer, and this electrical change detects touch input. The conductive layer is not particularly limited and can be any conventionally known transparent electrode material, such as indium tin oxide (ITO) conductive film, tin oxide conductive film, zinc oxide conductive film, or polymer conductive film. Furthermore, in organic material substrates (especially films) on which conductive layers such as electrodes and sensors are laminated, the hard coat layer described above may be formed on the surface opposite to the surface on which the conductive layers are provided.

[0076] The above laminate can also be used to create a display. For example, a laminate comprising a display element, an interlayer, and a surface protection panel can be used as a display. Furthermore, a touch panel can be added to the display to create a touch panel display. An example of a touch panel display is a laminate comprising a display element, an interlayer, a touch panel, an interlayer, and a surface protection panel in that order. The interlayer adheres and joins each component.

[0077] The surface protection panel is preferably an organic resin plate or an inorganic glass plate, but an inorganic glass plate is preferred. The surface protection panel may also be an OGS (one glass solution) panel, and sensors such as touch sensors may be provided on the surface protection panel. Therefore, the surface protection panel may be made of an inorganic glass plate with sensors attached.

[0078] Examples of display elements include organic EL display elements and liquid crystal display elements. It is preferable that a polarizing plate (polarizing film) is provided on the surface of the display element. 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 composed of the above-mentioned substrate resin film, and is preferably one of PET film, COP film, or TAC film. A hard coat layer made of (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 made of inorganic glass, an organic resin plate, or a resin film for a base material, with a touch sensor attached, but inorganic glass or a resin film for a base material with a touch sensor attached is preferred. Furthermore, in a touch panel, two or more inorganic glass, organic resin plates, or resin films for the substrate may be laminated to form a multilayer structure. In this case as well, it is preferable that a touch sensor be attached to either the inorganic glass, organic resin plate, or resin film for the substrate in the touch panel. Additionally, a protective film made of the resin film for the substrate may be placed on either the outermost surface of the front side or the outermost surface of the back side of the touch panel. Therefore, the bonding surface between the touch panel and the interlayer will be one of the inorganic glass, organic glass, or resin film for the substrate.

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

[0081] (Method for manufacturing laminates 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, placing one or more overlapping interlayer films between the pair of substrates, and then pressing them together. The bonding method is not particularly limited, but it is preferable to bond while heating. Alternatively, pre-bonding may be performed at a relatively low pressure and temperature, followed by final bonding at a higher pressure, temperature, or both than the pre-bonding method. When multiple interlayer films are arranged on a pair of substrates, it is preferable to integrate the multiple interlayer films during bonding.

[0082] Furthermore, in the case of laminated glass, for example, one or more interlayer films are placed between two glass members, and the air remaining between the two glass members and the interlayer films is removed by passing them through a pressure roll or by placing them in a rubber bag and applying reduced pressure and suction. Then, a laminated intermediate is obtained by pre-bonding at approximately 70 to 110°C. Next, the laminated intermediate is placed in an autoclave or pressed and bonded at approximately 120 to 150°C and a pressure of 1 to 1.5 MPa to complete the bonding process. In this way, laminated glass can be obtained. When multiple interlayer films are placed between a pair of glass members, it is preferable to integrate the multiple interlayer films during the pre-bonding and bonding processes.

[0083] The interlayer films, laminates, and laminated glass of the present invention can be used in a variety of fields, including electronic devices such as displays, solar cells, encapsulants for solar cells, vehicles such as automobiles, railway cars, aircraft, and ships, and various building structures such as buildings, apartments, detached houses, halls, and gymnasiums. Among these, use in vehicles and building structures is preferred, and use in building structures is more preferred. Laminated glass is preferable in vehicles and building structures. Furthermore, in vehicle applications, it is often used as window glass; for example, in automobiles, it is suitable for use in the windshield, rear window, or side windows. Furthermore, in building structures, it is suitable for use in window panes, glass floors, curtain walls, etc. When used in building structures, laminated glass may be made into large sheets, for example, or used as structural glazing. [Examples]

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

[0085] The various physical properties were measured and evaluated as follows.

[0086] [Thickness of the interlayer] The thickness of the intermediate film was measured by averaging 10 points using a microscope "DSX500" manufactured by Olympus Corporation.

[0087] [Content and neutralization degree of each structural unit] The mass percentages of each structural unit of the ethylene-(meth)acrylic acid copolymer and its ionomer resin were determined after performing the following hydrochloric acid treatment by 1 performing H-NMR and IR measurements. [Hydrochloric acid treatment] For 100 mg of the sample cryogenically pulverized using JFC-2000 (manufactured by Nippon Analytical Industry Co., Ltd.), 500 μL of ethanol and 1 mL of hydrochloric acid were added, and the mixture was stirred at 60 °C for 48 hours. Then, it was washed three times with ultrapure water to remove hydrochloric acid and dried by heating.

[0088] [Neutralization degree] The neutralization degree was determined by performing IR measurements on the samples before and after hydrochloric acid treatment, respectively. Based on the peak height of methylene at 1460 cm -1 the carboxylic acid peak height at 1700 cm -1 was calculated by the following formula. In the following formula, the denominator represents the peak height at 1700 cm -1 of the sample after hydrochloric acid treatment / the peak height at 1460 cm -1 and the numerator represents the peak height at 1700 cm -1 of the sample before hydrochloric acid treatment / the peak height at 1460 cm -1 of the sample.

Equation

[0089] [Yellowness (YI)] Using a spectrophotometer (Hitachi High-Tech Corporation "U-4100"), the YI value (yellowness, yellow index) of the obtained laminated glass was measured by transmission method in accordance with JIS K7105.

[0090] [λ1-λ2] (1) Fabrication of laminated glass Two clear glass sheets (5cm x 5cm x 2.5mm thick, visible light transmittance 90.4%, manufactured by Central Glass Co., Ltd.) conforming to JIS R3202 (2011) were prepared, along with interlayer films prepared in each example and comparative example, each measuring 5cm x 5cm. The interlayer films were sandwiched between the two clear glass sheets to obtain a laminate. This laminate was placed in a rubber bag, degassed at a vacuum of 0.08 MPa for 20 minutes, then transferred to an oven while still degassed, and vacuum-pressed at 90°C for 30 minutes to temporarily bond the laminate. The temporarily bonded laminate was then 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 sheet / interlayer / glass sheet.

[0091] (2) Measurement of λ1 (nm) The laminated glass prepared as described above was subjected to transmittance measurements in the wavelength range of 300 to 460 nm using a spectrophotometer (Hitachi High-Tech Corporation's "U-4100"). Then, we determined the smallest wavelength λ1 (nm) at which the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less in the region where the light transmittance is 10% or more. Specifically, in the region where the light transmittance is 10% or higher, the slope (increase in transmittance / increase in wavelength) between adjacent measurement points was calculated sequentially from the short wavelength side, and the point where the slope first becomes 1 or less was identified. Then, when the adjacent measurement points where the slope first becomes 1 or less were designated as λn(nm) and λm(nm), the wavelength at the midpoint between λn(nm) and λm(nm) was defined as λ1(nm).

[0092] (3) Measurement of λ² (nm) For each example and comparative example, a solution of the ultraviolet absorber was prepared at the same concentration (mass%) as the interlayer. Specifically, the ultraviolet absorber was dissolved in either THF or triethylene glycol bis(2-ethylhexanoate) (3GO) to prepare the solution. The solution prepared as described above was introduced into a cell with a 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"). Then, we determined the smallest wavelength λ2 (nm) at which the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less in the region where the light transmittance is 10% or more. Specifically, in the region where the light transmittance is 10% or higher, the slope (increase in transmittance / increase in wavelength) between adjacent measurement points was calculated sequentially from the short wavelength side, and the point where the slope first becomes 1 or less was identified. Then, when the adjacent measurement points where the slope first becomes 1 or less were designated 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 380nm and 420nm] Two clear glass sheets (5cm x 5cm x 2.5mm thick, visible light transmittance 90.4%, manufactured by Central Glass Co., Ltd.) conforming to JIS R3202 (2011) were prepared, along with interlayer films prepared in each example and comparative example, each measuring 5cm x 5cm. The interlayer films were sandwiched between the two clear glass sheets to obtain a laminate. This laminate was placed in a rubber bag, degassed at a vacuum of 0.08 MPa for 20 minutes, then transferred to an oven while still degassed, and vacuum-pressed at 90°C for 30 minutes to temporarily bond the laminate. The temporarily bonded laminate was then 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 sheet / interlayer / glass sheet. The transmittance at a wavelength of 380 nm (T380) and a wavelength of 420 nm (T420) was measured for the laminated glass prepared as described above using a spectrophotometer (Hitachi High-Tech Corporation "U-4100").

[0094] [Evaluation of suppression of yellowing] The interlayer films prepared in each example and comparative example were used as samples. The samples were cut into 5 cm squares, fixed to a stand, and stood upright. The edges of the samples were observed from the front, and the yellowness was evaluated by 10 evaluators in comparison to a color chart (yellowness 0.5). The following criteria were used to evaluate the suppression of yellowness. A: Three out of ten people rated it as yellower than the color sample. B: 4-5 out of 10 people rated it as yellower than the color sample. C: More than 6 out of 10 people rated it as yellower than the color sample.

[0095] [Evaluation of adhesion] (Manufacturing of laminated glass) The interlayers described in Examples 5 to 7 below were subjected to a Pammel test. The interlayers according to Examples 5 to 7 were sandwiched between two sheets of clear glass (300 mm x 300 mm) with a thickness of 2.5 mm in accordance with JIS R3202 (2011) to obtain a laminate. We fabricated two types of laminates: one with top-surface alignment, where the top surface of each layer was in contact with the interlayer, and another with bottom-surface alignment, where the bottom surface of each layer was in contact with the interlayer. The laminate was placed in a rubber bag, degassed at a vacuum of 0.08 MPa for 20 minutes, then transferred to an oven while still degassed, and vacuum-pressed at 90°C for 30 minutes to pre-compress the laminate. The pre-compressed laminate was then compressed 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 / glass plate.

[0096] (Pammel test) The resulting laminated glass was left to stand for 16 hours at a temperature of 23°C ± 0.6°C. After standing, the central part of the laminated glass (150 mm x 150 mm) was struck with a hammer with a head of 0.45 kg until the glass particle size was 6 mm or less. The other side was struck with the hammer the same number of times. The degree of exposure of the film after partial delamination of the glass was measured, and the Pammel value was determined according to Table 1 below. Measurements were performed on two pieces of laminated glass for each example, and the average value was calculated by taking the arithmetic mean of the four values ​​obtained from the measurement: the Pammel values ​​of the surface and the Pammel values ​​of the back surface. The Pammel value is a value used to measure the degree of adhesion between the interlayer and the glass plate. It is defined by the degree of exposure (area %) of the film after partial delamination of the glass, and is shown in Table 1. A higher Pammel value indicates stronger adhesion of the interlayer.

[0097] [Table 1]

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

[0099] <Ionomer resin> Details of the ionomer resin are as follows: [Table 2] *Ionomer resin 1 is an ionomer resin obtained by neutralizing an ethylene-methacrylic acid copolymer with magnesium ions.

[0100] <UV absorber> Compounds having a benzotriazole structure represented by formula (I): "RIASORB UV-234" manufactured by Rianlon, and compounds represented by formula (2), which are indicated as "UV-234" in Table 3. Compounds having a benzotriazole structure represented by formula (I): BASF's "Tinuvin 640", and the compound represented by formula (3), which is indicated as "UV-640" in Table 3. • Compounds containing a triazine structure: "UV-1164" manufactured by Lianglong, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol, indicated as "UV-1164" in Table 3. • Benzophenone-based UV absorber, "SEESORB 107" manufactured by Cipro Chemical Co., Ltd. Compounds with a benzotriazole structure that do not fall under formula (I): BASF's "Tinuvin-P"

[0101] [Example 1] (Fabrication of interlayers) An interlayer with a thickness of 1000 μm and the composition shown in Table 3 was obtained by kneading 100 parts by mass of ionomer resin 1 and 0.3 parts by mass of ultraviolet absorber at 170°C and extruding the mixture. Various evaluations were performed on this interlayer.

[0102] [Examples 2-4, Comparative Examples 1-3] An interlayer was prepared in the same manner as in Example 1, except that the composition of the resulting interlayer was changed as shown in Table 3. Various evaluations were performed on the interlayer.

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

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

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

[0106] [Table 3]

[0107] [Table 4]

[0108] The interlayers in each example contained UV absorbers, had low T380 (%) values, and exhibited good UV shielding performance. Furthermore, despite containing ionomer resin, they had low yellowness (YI) and suppressed discoloration. Furthermore, the results from Examples 5-7 demonstrate that an interlayer made by adding a silane coupling agent to an ionomer resin exhibits excellent adhesion regardless of the glass surface. The interlayer in Comparative Example 1 did not contain an ultraviolet absorber and had a low degree of yellowness, but it had a high T380 (%) value and poor ultraviolet shielding performance. The interlayer films of Comparative Examples 2 and 3 did not use the specific UV absorber described in the present invention, and were found to have a high degree of yellowness (YI), making them more susceptible to coloring than the interlayer films of the Examples.

Claims

1. An interlayer 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. The compound having the benzotriazole structure is one of the compounds of the following formulas (2) to (4): The ionomer resin comprises a constituent unit (A) derived from an unsaturated carboxylic acid, a constituent unit (B) derived from a neutralized unsaturated carboxylic acid, and a constituent unit (C) derived from ethylene, wherein the content of the constituent unit (B) derived from the neutralized unsaturated carboxylic acid is 10% by mass or more and 18% by mass or less based on the total amount of constituent units constituting the ionomer resin, and is an interlayer film. 【Chemistry 1】

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

3. The interfilm according to claim 1, wherein the ionomer resin comprises at least one of magnesium and zinc.

4. The interlayer according to claim 1, comprising a silane coupling agent.

5. The intermediate film according to claim 4, wherein the silane coupling agent is a silane coupling agent having an epoxy group.

6. The interlayer according to claim 4, 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 is considered as 100% by mass.

7. A laminate comprising the interlayer film described in claim 1 and a pair of substrates, wherein the interlayer film is disposed between the pair of substrates.

8. The laminate according to claim 7, which is a laminated glass.

9. The laminate according to claim 7, which is laminated glass for building structures.

10. The process involves kneading an ionomer resin with a mixture of an ultraviolet absorber and an ethylene-(meth)acrylic acid copolymer to obtain a resin composition. The process of extruding the resin composition and A method for producing an interlayer film according to claim 1, comprising:

11. The interfilm according to any one of claims 1 to 6, wherein the ionomer resin contains magnesium.

12. The interlayer according to any one of claims 1 to 6, wherein the ionomer resin contains only one type of metal ion.

13. The ionomer resin comprises a constituent unit (A) derived from an unsaturated carboxylic acid, a constituent unit (B) derived from an unsaturated carboxylic acid neutralized product, and a constituent unit (C) derived from ethylene, wherein the total content of the constituent unit (A) derived from the unsaturated carboxylic acid and the constituent unit (B) derived from the unsaturated carboxylic acid neutralized product is 10% by mass or more and 25% by mass or less based on the total amount of constituent units constituting the ionomer resin, as described in any one of claims 1 to 6.

14. The intermediate film according to any one of claims 1 to 6, wherein the degree of neutralization of the ionomer resin is 50% or more and 75% or less.

15. The interlayer according to any one of claims 1 to 6, wherein the difference between wavelength λ1 (nm) and wavelength λ2 (nm) measured by the following method (λ1 - λ2) is 20 nm or less. (measurement) The wavelength λ1 is the smallest wavelength (nm) in the region of 300 to 460 nm where the increase in transmittance (%) with respect to the increase in wavelength (nm) is 1 or less, in the region where the light transmittance is 10% or more, when measuring the transmittance of laminated glass obtained by sandwiching the interlayer between two clear glass sheets with a thickness of 2.5 mm. The wavelength λ2 is the smallest wavelength (nm) in the wavelength range of 300 to 460 nm, in the region where the light transmittance is 1 or less in proportion to the increase in wavelength (nm), when a transmittance measurement is performed on the solution of ultraviolet absorber with the same concentration (mass%) as the concentration (mass%) of ultraviolet absorber contained in the interlayer, under the conditions of an optical path length L (mm) defined below. If the thickness of the interlayer is greater than 0 mm and less than 1.5 mm, the optical path length L shall be 1 mm; if the thickness of the interlayer is 1.5 mm or more and less than 2.5 mm, the optical path length L shall be 2 mm; if the thickness of the interlayer is 2.5 mm or more and less than 3.5 mm, the optical path length L shall be 3 mm; and if the thickness of the interlayer is 3.5 mm or more, the optical path length L shall be the length obtained by rounding the thickness of the interlayer (mm) to the first decimal place.

16. An interlayer according to any one of claims 1 to 6, comprising a single-layer film consisting of a single layer.

17. A method for using the interlayer film according to any one of claims 1 to 6 to bond a pair of substrates.

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