Interlayer film

Abstract

An interlayer film according to the present invention comprises 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, wherein the content of the ultraviolet absorber is 0.04-0.18 mass%, and the content of structural units having a un-neutralized carboxylic acid, with respect to the total amount of resin containing a structural unit derived from unsaturated carboxylic acid, is 2.5-4.3 mol%.　The present invention makes it possible to provide an interlayer film having a high adhesive strength, a high UV blocking ratio, and good transparency.

Description

Interlayer

[0001] This invention relates to an interlayer used in laminated glass and the like.

[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 two panes of glass 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. Patent Document 1 describes an invention relating to laminated glass with improved impact resistance and penetration resistance, in which a thermosetting resin is interposed between an ionomer resin, in which the intermolecules of an ethylene-methacrylic acid copolymer are bonded with metal ions, and an organic peroxide and a silane coupling agent. Patent Document 2 describes a resin sheet with excellent transparency and adhesion to glass tin surfaces, comprising a resin composition containing a zinc ionomer of an ethylene-unsaturated carboxylic acid copolymer and a silane coupling agent, wherein the unsaturated carboxylic acid content of the ethylene-unsaturated carboxylic acid copolymer and the degree of neutralization by zinc ions are within a specific range. Patent Document 3 describes an invention relating to a resin composition containing an ethylene acid copolymer, which contains ethylene residues and carboxylic acid residues, and whose degree of neutralization and melt index are within a specific range, for the purpose of improving transparency and adhesion to glass. Patent Document 4 discloses a resin composition for laminated glass interlayers with improved weather resistance, comprising an ionomer of an ethylene-unsaturated carboxylic acid copolymer, a dye, and an ultraviolet absorber.

[0004] Ionomer resins are used in applications other than interlayers for laminated glass. For example, Patent Document 5 describes the use of a crosslinkable ethylene copolymer composition for encapsulating solar cells in solar cell modules.

[0005] Japanese Patent Publication No. 9-30846, Japanese Patent Publication No. 2016-188158, Japanese Patent Publication No. 2009-541523, Japanese Patent Publication No. 2024-086668, Japanese Patent Publication No. 2008-120952

[0006] Ionomer resins are often used as interlayers in laminated glass, particularly for architectural applications, because they can improve rigidity. Furthermore, interlayers are generally required to have high adhesion to glass, a high UV protection rate, and excellent transparency.

[0007] To ensure high adhesion, silane coupling agents are commonly used in addition to ionomer resins. However, when silane coupling agents are incorporated into ionomer resins, they tend to become yellowish and their transparency decreases. Therefore, an interfilm is needed that can achieve high adhesion with a small amount of silane coupling agent while still containing ionomer resin. Furthermore, to achieve a high UV protection rate, UV absorbers are used. However, when UV absorbers are incorporated into ionomer resins, they tend to become yellowish and their transparency decreases.

[0008] However, compositions containing ionomer resins disclosed in the prior art had room for improvement in terms of satisfying all physical properties such as high adhesion to glass, high UV cut rate, and transparency. Therefore, the object of the present invention is to provide an interfilm with high adhesion, high UV cut rate, and good transparency.

[0009] As a result of diligent research, the present inventors have found that the above problems can be solved by an interlayer containing an ionomer resin and a certain amount of a specific type of ultraviolet absorber, and in which the content of constituent units having an unneutralized carboxylic acid is adjusted to a specific range, and have completed the present invention as follows. That is, the present invention provides the following [1] to [8]. [1] An interlayer 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, wherein the content of the ultraviolet absorber is 0.04 to 0.18% by mass, and the content of constituent units having an unneutralized carboxylic acid is 2.5 to 4.3 mol% based on the total amount of resin including constituent units derived from an unsaturated carboxylic acid. [2] The interlayer according to [1], wherein the compound having a benzotriazole structure includes a compound represented by the following general formula (I). (In the above formula, R １ R is an organic group having 4 or more carbon atoms. ２ ~R ８ (Each of these is independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.) [3] The interlayer according to [1] or [2] above, wherein the compound having the benzotriazole structure comprises any of the compounds of the following formulas (2) to (4). [4] The intermediate film according to any one of [1] to [3] above, wherein the compound having the benzotriazole structure includes the compound of the following formula (3). [5] An interlayer according to any one of [1] to [4] above, wherein the content of the constituent units having the unneutralized carboxylic acid is 2.5 to 3.5 mol%. [6] An interlayer according to any one of [1] to [5] above, comprising a silane coupling agent. [7] An interlayer according to any one of [1] to [6] above, wherein the Pammel value is 6 or more. [8] An interlayer according to any one of [1] to [7] above, wherein the ionomer resin is a resin neutralized with magnesium ions. [9] An interlayer according to any one of [1] to [8] above, wherein the bending rigidity at 50°C of the laminated glass obtained by bonding two 2.75 mm thick glass sheets with an interlayer in between is 700 N / mm or more.

[0010] According to the present invention, it is possible to provide an interlayer film with high adhesive strength, high UV protection rate, and good transparency.

[0011] This is a schematic diagram illustrating a method for measuring bending stiffness.

[0012] <Interlayer> The interlayer of the present invention contains an ionomer resin and an ultraviolet absorber. 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 content of the ultraviolet absorber is 0.04 to 0.18% by mass. In addition, in the interlayer, the content of constituent units having unneutralized carboxylic acid, based on the total amount of resin containing constituent units derived from unsaturated carboxylic acid, is 2.5 to 4.3 mol%. The interlayer of the present invention will be described in detail below.

[0013] [UV Absorber] The interlayer of the present invention contains at least one UV absorber selected from the group consisting of compounds having a benzotriazole structure and compounds having a triazine structure. By including a predetermined amount of such a UV absorber, as described later, the UV cut rate can be increased while maintaining good transparency of the interlayer. In particular, from the viewpoint of improving the UV cut rate of the interlayer, it is preferable that the UV absorber contains at least a compound having a benzotriazole structure.

[0014] As a compound having a benzotriazole structure, a compound represented by the following general formula (I) is preferred from the viewpoint of easily suppressing the discoloration of the interlayer and improving transparency. (In the above formula, R １ R is an organic group having 4 or more carbon atoms. ２ ~R ８ Each of these is independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.

[0015] R in the above formula (I) １ It is an organic group with 4 or more carbon atoms. This makes it easier to suppress the coloration of the interlayer. The reason for this is not clear, but R １is a group 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 becomes easier to suppress the coordination between the ultraviolet absorber and the metal possessed by the ionomer resin. As a result, it is presumed that the coloring of the intermediate film can be suppressed.

[0016] R １ From the viewpoint of suppressing the coloring of the intermediate film, it is preferably an organic group having 4 or more and 20 or less carbon atoms, and more preferably an organic group having 4 or more and 10 or less carbon atoms. R １ may contain an oxygen atom, a nitrogen atom, a sulfur atom, etc., but is preferably a hydrocarbon group. That is, R １ is preferably a hydrocarbon group having 4 or more carbon atoms, more preferably a hydrocarbon group having 4 or more and 20 or less carbon atoms, and even more preferably a hydrocarbon group having 4 or more and 10 or less carbon atoms. Further, R １ preferably has either or both of a quaternary carbon atom and an aromatic ring. By having such a structure, it becomes easier to further suppress the coordination between the ultraviolet absorber and the metal possessed by the ionomer resin. As a result, it is presumed that the coloring of the intermediate film can be further suppressed. R １ is particularly preferably a group represented by the following formula (a) or formula (b). The * in formula (a) and formula (b) is a bond that binds to the aromatic ring shown in formula (I).

[0017] 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, iodine, etc., and chlorine is preferred. The organic group may contain an oxygen atom, a nitrogen atom, a sulfur atom, etc., or may be a hydrocarbon group. R in the above formula (I) ２ 、R ４ 、R ５ 、R ６ 、R ７ 、and R ８Each of these is 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 preferred. ２ ~R ８ In this, at least one is preferably a branched alkyl group, and more preferably a branched alkyl group having 4 to 10 carbon atoms. When a compound having a benzotriazole structure is equipped with a branched alkyl group, its compatibility with ionomer resins having ethylene-derived structural units (described later) is improved, and the haze of the interlayer tends to be reduced.

[0018] R in the above formula (I) ３ R is a hydrogen atom or an organic group having 1 to 20 carbon atoms. This organic group may include oxygen atoms, nitrogen atoms, sulfur atoms, etc., or it may be a hydrocarbon group. ３ From the viewpoint of suppressing discoloration of the interlayer film, it is preferable that the group is 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. ３ It is preferably a branched alkyl group, and more preferably a branched alkyl group having 4 to 10 carbon atoms. ３ It is preferably a group represented by the following formulas (c), (d), or (e), and is particularly preferably a branched alkyl group (d). In formulas (c), (d), and (e), the asterisk (*) represents a bond that connects to the aromatic ring shown in formula (I).

[0019] From the viewpoint of suppressing discoloration of the interlayer of the present invention, among the compounds having the benzotriazole structure of formula (I), any of the following compounds (2) to (4) are preferred.

[0020] Among the compounds having the benzotriazole structure, from the viewpoint of suppressing the coloring of the intermediate film, the compound of the following formula (3) is particularly preferable.

[0021] In the intermediate film of the present invention, a compound having a triazine structure may be used as the ultraviolet absorber. The triazine structure means an unsaturated six-membered ring structure containing three nitrogens, and specifically, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, etc. can be mentioned. Among the compounds having a triazine structure, from the viewpoint of suppressing the coloring of the intermediate film, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol is preferable.

[0022] The content of at least one ultraviolet absorber selected from the group consisting of the compound having a benzotriazole structure and the compound having a triazine structure in the present invention is 0.04 to 0.18% by mass based on the total amount of the intermediate film. When the content of the above ultraviolet absorber is less than 0.04% by mass, the ultraviolet cut-off rate of the intermediate film deteriorates. Further, when the content of the above ultraviolet absorber exceeds 0.18% by mass, the intermediate film is likely to be colored and the transparency decreases. The content of the ultraviolet absorber in the intermediate film is preferably 0.04 to 0.14% by mass, more preferably 0.05 to 0.12% by mass.

[0023] The intermediate film may contain other ultraviolet absorbers other than the compound having a benzotriazole structure and the compound having a triazine structure as long as the effects of the present invention are not inhibited. From the viewpoint of suppressing the coloring of the intermediate film, etc., the content of the other ultraviolet absorber is preferably 1% by mass or less, more preferably 0.2% by mass or less, and further preferably 0% by mass based on the total amount of the intermediate film.

[0024] The content of the UV absorber in the intermediate film can be confirmed by quantitative analysis after identifying the type of the UV absorber by qualitative analysis. The qualitative analysis may be performed using NMR, IR, GPC, thermal decomposition GC / MS, solution GC / MS, a melting point measuring instrument, or the like. The quantitative analysis can be performed using GPC. Specifically, after creating a calibration curve relating the peak area and the concentration using a standard product, an additive solution (a solution containing a UV absorber) extracted from a sample (intermediate film) is analyzed by GPC. The additive solution can be prepared, for example, by freeze-grinding a sample (intermediate film), dissolving it in a good solvent (a solvent capable of dissolving the resin and the UV absorber), adding a poor solvent (a solvent incapable of dissolving the resin but capable of dissolving the UV absorber) to reprecipitate the resin, and recovering the supernatant. Then, the additive solution thus prepared may be filtered using a syringe filter or the like and then analyzed by GPC. When two or more types of UV absorbers are contained and it is difficult to perform quantitative analysis without separating them in the analysis by GPC, silica gel column chromatography may be appropriately used to separate the plurality of UV absorbers and then quantitative analysis may be performed by GPC. As the detector of GPC, for example, a UV detector can be used. Regarding the set wavelength of the UV detector, when one type of UV absorber is contained in the intermediate film, it is desirable to measure at 350 nm. When two or more types are contained, it is desirable to obtain the absorption spectra of each, select a region with little spectral overlap, and select a value close to 400 nm within that region for measurement. It is desirable to perform qualitative analysis before performing quantitative analysis of the UV absorber.

[0025] [Ionomer Resin] The interlayer of the present invention contains an ionomer resin. Examples of ionomer resins include resins containing constituent units derived from unsaturated carboxylic acids, such as 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, monoethyl maleate, etc. In the ionomer resin, one unsaturated carboxylic acid may be used alone, or two or more may be used in combination. Among these, acrylic acid and methacrylic acid are preferred. Therefore, the ionomer resin is preferably an ionomer resin of ethylene-(meth)acrylic acid copolymer. Note that (meth)acrylic acid means at least one of methacrylic acid or acrylic acid, and the same applies to the following similar terms.

[0026] 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. Among these, at least one of magnesium and zinc is preferred, and magnesium is particularly preferred. A single metal ion may be used, or two or more may be used in combination. When at least one of magnesium and zinc, particularly magnesium, is used as the metal ion, an appropriate cross-linking structure is formed, making it easier to increase the bending stiffness at both 25 and 50°C.

[0027] When an ionomer resin is an ethylene-unsaturated carboxylic acid copolymer, it typically contains constituent units (A) derived from ethylene, constituent units (B) derived from neutralized unsaturated carboxylic acid, and constituent units (C) derived from unsaturated carboxylic acid. The carboxylic acid in constituent unit (C) is a carboxylic acid that has not been neutralized by metal ions. In this specification, constituent unit (C) derived from unsaturated carboxylic acid may also be referred to as constituent unit (C) having unneutralized carboxylic acid. In particular, when an ionomer resin is an ethylene-(meth)acrylic acid copolymer, it typically contains constituent units (A) derived from ethylene, constituent units (B) derived from neutralized (meth)acrylic acid, and constituent units (C) derived from (meth)acrylic acid. The constituent units derived from (meth)acrylic acid correspond to constituent unit (C) having unneutralized carboxylic acid. By containing these constituent units (A), (B), and (C), the ionomer resin enhances adhesive strength and makes it easier to achieve excellent bending stiffness at 25°C and 50°C.

[0028] The monomer constituting the constituent unit (C) 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. Among these, methacrylic acid is more preferable from the viewpoint of bending rigidity and adhesiveness. Constituent unit (C) is a constituent unit that has not been neutralized by a metal ion. Constituent unit (B) is a neutralized product of the constituent unit derived from the above 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 a methacrylic acid neutralized product. Constituent unit (B) is a constituent unit in which the hydrogen ions of the carboxyl group in the unsaturated carboxylic acid are replaced 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 from the viewpoint of forming an appropriate crosslinking structure and making it easier to increase rigidity, at least one of magnesium and zinc is preferred, and magnesium is particularly preferred. Therefore, it is preferable that constituent unit (B) contains at least one of magnesium and zinc, and it is particularly preferable that it contains magnesium. In other words, the ionomer resin is preferably a resin neutralized with magnesium ions.

[0029] The ionomer resin may be obtained by neutralizing a copolymer of ethylene and an unsaturated carboxylic acid with metal ions, or by neutralizing a copolymer of ethylene, an unsaturated carboxylic acid, and monomers other than ethylene and an unsaturated carboxylic acid with metal ions. Therefore, in addition to constituent units (A), (B), and (C), the ionomer resin may also contain constituent units other than constituent units (A), (B), and (C) (hereinafter also referred to as "other constituent units").

[0030] 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.

[0031] The ionomer resin may also 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] The ionomer resin has a melt mass flow rate (MFR) measured in accordance with JIS K7210:1999 under conditions of 190°C and a 2160g load, which, from the viewpoint of processability and mechanical strength, is, for example, 0.01 g / 10 min to 150 g / 10 min, preferably 0.01 g / 10 min to 50 g / 10 min, more preferably 0.1 g / 10 min to 30 g / 10 min, and even more preferably 0.1 g / 10 min to 10 g / 10 min.

[0033] The ionomer resin content in the interlayer is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, when the total amount of the interlayer is considered to be 100% by mass. By setting the ionomer resin content to be above the above lower limit, the rigidity and interlayer adhesion of the resulting laminated glass can be improved. Furthermore, when the total amount of the interlayer is considered to be 100% by mass, the ionomer resin content in the interlayer may be, for example, 99.96% by mass or less, or 99.9% by mass or less, from the viewpoint of including a certain amount or more of additives. In addition, when the interlayer contains other resin components as described later, it is preferable to keep the ionomer resin content in the interlayer below a certain amount, for example, 98% by mass or less, 95% by mass or less, or 90% by mass or less.

[0034] The ionomer resin content in the interlayer is preferably 50 to 99.96% by mass, more preferably 55 to 99.9% by mass, and even more preferably 60 to 98% by mass.

[0035] 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.

[0036] [Other Resin Components] The interlayer may contain other resin components in addition to the ionomer resin described above. The ionomer resin may become too viscous during mixing, reducing its moldability, such as extrusion. However, by including other resin components in the interlayer, it becomes easier to improve the moldability, such as extrusion. The other resin component is preferably a resin that is compatible with the ionomer resin. From the viewpoint of compatibility with the ionomer resin, examples of other resin components include resins containing constituent units derived from unsaturated carboxylic acids, and among these, ethylene-unsaturated carboxylic acid copolymers are preferred. Here, the unsaturated carboxylic acid used in the ethylene-unsaturated carboxylic acid copolymer is as described above, with (meth)acrylic acid being preferred, and methacrylic acid being more preferred. Therefore, ethylene-(meth)acrylic acid copolymers are preferred as the other resin.

[0037] Ethylene-unsaturated carboxylic acid copolymers used as other resins can also be described as copolymers containing constituent units (A) derived from ethylene and constituent units (C) derived from unsaturated carboxylic acid (constituent units (C) having unneutralized carboxylic acid). Ethylene-unsaturated carboxylic acid copolymers are typically ethylene-(meth)acrylic acid copolymers. Ethylene-(meth)acrylic acid copolymers are copolymers containing constituent units (A) derived from ethylene and constituent units (C) derived from (meth)acrylic acid (constituent units (C) having unneutralized carboxylic acid.

[0038] Furthermore, ethylene-unsaturated carboxylic acid copolymers used as other resins may contain constituent units other than (A) and (C) (other constituent units (D)). Examples of other constituent units include constituent unit (D) derived from alkyl (meth)acrylate. Therefore, ethylene-unsaturated carboxylic acid copolymers may consist only of constituent units (A) and (C), but they may also contain constituent units (D) derived from alkyl (meth)acrylate in addition to constituent units (A) and (C). Details of alkyl (meth)acrylate are as described above.

[0039] From the viewpoint of compatibility and extrudeability, it is preferable that the other resin components be copolymers of the same type as those used in the ionomer resin, and more preferably that the resin be used before neutralization with metal ions to obtain the ionomer resin. Therefore, if the ionomer resin is an ionomer resin of ethylene-(meth)acrylic acid copolymer, it is preferable that the other resin components be ethylene-(meth)acrylic acid copolymers. Also, if the ionomer resin is an ionomer resin of ethylene-methacrylic acid copolymer, it is preferable that the other resin components be ethylene-methacrylic acid copolymers.

[0040] The content of other resin components is, for example, 1.5% to 40% by mass, preferably 3% to 30% by mass, when the total amount of the interlayer film is considered to be 100% by mass. By setting the content of other resin components above the lower limit, the complex viscosity of the ionomer resin is reduced, making it easier to improve extrudeability. Furthermore, by setting the content of other resin components below the upper limit, it is possible to prevent a decrease in bending rigidity even when other resin components are included. The content of other resin components is more preferably 3% to 25% by mass, and even more preferably 5% to 15% by mass, when the total amount of the interlayer film is considered to be 100% by mass. However, other resin components do not have to be used in the interlayer film, and the resin component in the interlayer film may consist of an ionomer resin. In addition, interlayer films generally often contain polyvinyl acetal resin, but from the viewpoint of bending rigidity and impact resistance, it is preferable that the interlayer film of the present invention does not contain polyvinyl acetal resin. Furthermore, if the interlayer contains polyvinyl acetal resin in addition to the ionomer resin, the transparency of the interlayer decreases. From this viewpoint as well, it is preferable that the interlayer of the present invention does not contain polyvinyl acetal resin.

[0041] The content of the resin component in the interlayer (for example, the total amount of ionomer resin and other resins) is not particularly limited when the total amount of the interlayer is considered to be 100% by mass, but is, for example, 60% by mass or more and 100% by mass or less, preferably 70% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less.

[0042] (Content of constituent units) The content of constituent units (A) derived from ethylene, constituent units (B) derived from neutralized unsaturated carboxylic acid, and constituent units (C) containing unneutralized carboxylic acid in the interlayer film will be explained below. Note that the constituent units (C) containing unneutralized carboxylic acid described below include not only those contained in the ionomer resin, but also those contained in resins containing constituent units derived from unsaturated carboxylic acid that are not ionomer resins. Similarly, the constituent units (A) derived from ethylene include not only those contained in the ionomer resin, but also those contained in resins containing constituent units derived from unsaturated carboxylic acid that are not ionomer resins. Furthermore, other constituent units (D) also include constituent units (D) contained in resins containing constituent units derived from unsaturated carboxylic acid that are not ionomer resins. Furthermore, the content of each constituent unit is based on the total amount of resin containing constituent units derived from unsaturated carboxylic acid, as described below. That is, when using an ionomer resin of an ethylene-unsaturated carboxylic acid copolymer and an ethylene-unsaturated carboxylic acid copolymer that is not an ionomer resin, the total amount of both is used as the basis. However, the interlayer does not necessarily have to contain an ethylene-unsaturated carboxylic acid copolymer as described above.

[0043] In the interlayer, the content of constituent units (C) having unneutralized carboxylic acid is 2.5 to 4.3 mol% based on the total amount of resin containing constituent units derived from unsaturated carboxylic acid. If the content of constituent units (C) having unneutralized carboxylic acid is less than 2.5 mol%, the adhesion to glass will be low, and the Pammel value described later will be small. If the content of constituent units (C) having unneutralized carboxylic acid is greater than 4.3 mol%, it will be more prone to discoloration and transparency will deteriorate. The content of constituent units (C) having unneutralized carboxylic acid is preferably 2.5 to 3.5 mol%, and more preferably 2.5 to 3.3 mol%.

[0044] In the interlayer, the content of constituent units (B) derived from unsaturated carboxylic acid neutralized products is, for example, 2 mol% to 15 mol%, preferably 2.5 mol% to 10 mol%, and more preferably 3 mol% to 8 mol%. When the content of constituent units (B) is above the lower limit, the degree of crosslinking of the ionomer resin increases, making it easier to increase the bending stiffness, especially the bending stiffness at 50°C. It also makes it easier to increase transparency and heat resistance. By keeping the content of constituent units (B) below the upper limit, it becomes easier to improve the flexibility, adhesion, mechanical strength, and processability of the interlayer.

[0045] In the interlayer, the total content of constituent units (B) derived from neutralized unsaturated carboxylic acid and constituent units (C) having unneutralized carboxylic acid is preferably 5 mol% to 20 mol%, more preferably 6 mol% to 15 mol%, and even more preferably 7 mol% to 12 mol%, based on the total amount of resin containing constituent units derived from unsaturated carboxylic acid. If the total content of constituent units (B) and (C) is above the lower limit, the transparency, heat resistance, and mechanical strength of the interlayer can be improved. Furthermore, if the total content of constituent units (B) and (C) is below the upper limit, flexibility, processability, and adhesion can be improved.

[0046] In the interlayer, the content of ethylene-derived constituent units (A) is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more, based on the total amount of resin containing unsaturated carboxylic acid-derived constituent units, from the viewpoint of easily improving the impact resistance of the ionomer resin. Furthermore, the content of ethylene-derived constituent units (A) is preferably 95 mol% or less, more preferably 93 mol% or less, from the viewpoint of transparency, mechanical strength, and moldability.

[0047] As described above, the ionomer resin may contain other constituent units (D), such as constituent units derived from alkyl (meth)acrylate. The content of other constituent units (D) is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 2 mol% or less, based on the total amount of resin containing constituent units derived from unsaturated carboxylic acid. Furthermore, from the viewpoint of increasing rigidity at high temperatures, the less the content of constituent units (D), the better, and it is sufficient if it is 0 mol% or more, and it is preferable that the ionomer resin does not contain any constituent units (D).

[0048] Furthermore, while isobutyl (meth)acrylate, and especially isobutyl 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, in the interlayer film, the content of constituent units derived from isobutyl (meth)acrylate is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 2 mol% or less, based on the total amount of resin containing constituent units derived from unsaturated carboxylic acid. Moreover, the content of constituent units derived from isobutyl (meth)acrylate may be 0 mol% or more, and it is preferable that the ionomer resin does not contain any constituent units derived from isobutyl (meth)acrylate.

[0049] (Degree of Neutralization) The degree of neutralization of the ethylene-unsaturated carboxylic acid copolymer and its ionomer resin contained in the interlayer is, for example, 30% or more, but preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and even more preferably 55% or more. A higher degree of neutralization tends to increase the bending stiffness, especially the bending stiffness at 50°C. Furthermore, the degree of neutralization of the ethylene-unsaturated carboxylic acid copolymer and its ionomer resin is not particularly limited, but preferably 95% or less, more preferably 90% or less, even more preferably 80% or less, and even more preferably 75% or less. By keeping the degree of neutralization below a certain value, the flexibility, adhesion, mechanical strength, processability, etc. of the interlayer can be improved. In this specification, the degree of neutralization refers to the percentage (%) of carboxyl groups that are neutralized by metal ions out of the total carboxyl groups contained in the ethylene-unsaturated carboxylic acid copolymer and its ionomer resin contained in the interlayer.

[0050] The degree of neutralization 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 interlayer film can be determined by mass spectrometry and １ This can be calculated by performing 1H-NMR measurements and analyzing the integrated intensity ratio of the hydrogen peaks originating from each monomer, as well as the degree of neutralization.

[0051] [Silane Coupling Agent] The interlayer may contain additives. The interlayer may contain, for example, a silane coupling agent as an additive. By containing a silane coupling agent, the interlayer can more easily improve its adhesion to substrates, glass, etc. A silane coupling agent is a compound having a Si atom, a reactive group Y selected from organic functional groups such as vinyl groups, epoxy groups, amino groups, (meth)acryloyl groups, and mercapto groups, and a hydrolysis group OR selected from methoxy groups, ethoxy groups, etc. (OR may all be the same or different, and n is 0 to 2). More specifically, silane coupling agents include those having groups containing polymerizable carbon-carbon double bonds such as vinyl groups and (meth)acryloyl groups, organic functional groups such as amino groups and epoxy groups, and alkoxy groups.

[0052] 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 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 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.

[0053] 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-aminopropyltrimethoxysilane are preferred. From the viewpoint of improving adhesion to glass and substrates, the content of the silane coupling agent in the interlayer film is, for example, 0.001% by mass or more, preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.03% by mass or more, when the total amount of the interlayer film is 100% by mass. Furthermore, from the viewpoint of suppressing discoloration, the content of the silane coupling agent in the interlayer film is, for example, 1% by mass or less, preferably 0.5% by mass or less, and more preferably 0.3% by mass or less, when the total amount of the interlayer film is 100% by mass.

[0054] [Additives] In addition to the UV absorber and silane coupling agent mentioned above, the intermediate film may contain at least one of the following additives: an antioxidant and other known additives.

[0055] Examples of antioxidants include phenolic compounds, phosphoric acid compounds, and sulfur compounds. Antioxidants prevent oxidative degradation of the interlayer film, thereby improving durability. Antioxidants may be used individually or in combination of two or more types.

[0056] The interlayer may contain known additives other than 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, etc. From the viewpoint of design, it is preferable that the interlayer contains a colorant. From the viewpoint of transparency, it is preferable that the interlayer does not contain a colorant.

[0057] [Pammel Value] The interlayer of the present invention preferably has a pammel value of 6 or higher, more preferably 7 or higher, and even more preferably 8 or higher, from the viewpoint of improving adhesion to the glass and preventing peeling, foaming, etc. The pammel value is 9 or lower. The pammel value can be determined by measuring it on laminated glass obtained by bonding two pieces of glass with a thickness of 2.75 mm (measured value, nominal value is 3 mm) via an interlayer. Details of the method for measuring the pammel value and the method for manufacturing the laminated glass used for measuring the pammel value are shown in the examples. The 2.75 mm glass used for measuring the pammel value is clear glass, and details thereof are also shown in the examples.

[0058] The Pammel value can be adjusted by the type of resin and additives contained in the interlayer. For example, increasing the content of constituent units with unneutralized carboxylic acids makes it easier to raise the Pammel value. Additionally, including a silane coupling agent in the interlayer can also increase the Pammel value.

[0059] [Bending Stiffness] The interlayer of the present invention preferably has a bending stiffness of 700 N / mm or more at 50°C for laminated glass obtained by bonding two pieces of glass with a thickness of 2.75 mm (measured value, nominal value is 3 mm) via an interlayer for laminated glass. A bending stiffness of 700 N / mm or more at 50°C ensures high static stiffness regardless of changes in ambient temperature, making it suitable for use in building applications. A bending stiffness of 800 N / mm or more at 50°C is more preferable, and 900 N / mm or more is even more preferable. While a higher bending stiffness of the interlayer at 50°C is desirable, from the viewpoint of ensuring a certain degree of flexibility in the interlayer, it may be, for example, 3000 N / mm or less, or 2000 N / mm or less.

[0060] Furthermore, the interlayer of the present invention preferably has a bending rigidity of 1000 N / mm or more at 25°C for laminated glass obtained by bonding two 2.75 mm thick glass sheets with the interlayer in between. A bending rigidity of 1000 N / mm or more at 25°C ensures high static rigidity around 25°C, making it suitable for use in building applications. A bending rigidity of 1200 N / mm or more at 25°C is more preferably, 1300 N / mm or more is even more preferably, and 1400 N / mm or more is even more preferably. While a higher bending rigidity of the interlayer at 25°C is desirable, from the viewpoint of ensuring a certain degree of flexibility in the interlayer, it may be, for example, 4000 N / mm or less, 3000 N / mm or less, 2300 N / mm or less, or 2000 N / mm or less.

[0061] Bending stiffness can be adjusted by the type of resin, the composition of the monomers constituting the resin, and the thickness of the interlayer. For example, using ionomer resin makes it easier to increase bending stiffness, and using high-Tg monomers in the ionomer resin while reducing the low-Tg component or increasing the degree of neutralization makes it easier to increase bending stiffness at 50°C. In addition, when other resin components are included in addition to ionomer resin, reducing the content of the other resin components makes it easier to maintain high bending stiffness, especially at high temperatures.

[0062] The bending stiffness at 50°C or 25°C mentioned above is best measured by first pre-pressing two 2.75 mm thick glass sheets with an interlayer in between, then performing the final pressing in an autoclave to obtain a laminated glass for measurement, and finally curing the laminated glass for measurement for one week, then measuring it in an environment of 25°C or 50°C. The manufacturing conditions for the laminated glass for measurement should be as shown in the manufacturing method of laminated glass described in the examples below. The 2.75 mm glass used for bending stiffness measurement is float glass, and its details are as shown in the examples.

[0063] [Thickness] The thickness of the interlayer is not particularly limited, but is, for example, 0.2 mm or more and 6 mm or less, preferably 0.6 mm or more and 4.5 mm or less, and more preferably 1.5 mm or more and 3.6 mm or less. Setting the thickness of the interlayer above a certain level makes it easier to improve bending rigidity, adhesion, etc. Also, by keeping it below the above upper limit, it is possible to prevent the interlayer from becoming unnecessarily thick, and it becomes easier to manufacture it in a general-purpose manner. It also becomes easier to ensure transparency, etc.

[0064] 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. A width of 2 m or more is more preferable. 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. Furthermore, the interlayer is preferably an extruded product obtained by extrusion molding, as described later. Being an extruded product makes it easy to industrially mass-produce large-format interlayers with a width of 1 m or more, as described above.

[0065] The interlayer of the present invention consists of a single layer, and 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 a resin component such as an ionomer resin, and containing at least one ultraviolet absorber (a predetermined ultraviolet absorber) selected from the group consisting of compounds having a benzotriazole structure and compounds having a triazine structure. The interlayer may also be a multilayer film of two or more layers. In a multilayer film, the overall composition of the interlayer may be as described above for the interlayer, but it is preferable that the resin composition constituting each layer has the composition described above for the interlayer. That is, each layer may consist of a resin composition containing a resin such as an ionomer resin, and a predetermined ultraviolet absorber, as described above for the interlayer. In a multilayer film, the compositions of each layer may be different from or the same. In single-layer or multi-layer films, the content of ionomer resin, the content of other resin components, and the content of a specified ultraviolet absorber 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.

[0066] [Method for Manufacturing Interlayer Films] Interlayer films can be manufactured by obtaining a resin composition for forming an interlayer film and then molding the interlayer film from the resin composition. Interlayer films can be manufactured by mixing components that constitute the interlayer film, such as a resin component, a predetermined ultraviolet absorber, and other additives added as needed, to obtain a resin composition, and then appropriately heating and melting the obtained resin composition to form a film, such as by extrusion molding, press molding, or roll molding, to obtain an interlayer film. The method for mixing each component to obtain the resin composition is not particularly limited, but a method of kneading using an extruder is preferred. Furthermore, if the interlayer film consists of multiple layers, resin compositions for forming each layer can be prepared, and the obtained resin compositions can be appropriately heated and melted to form each layer, such as by extrusion molding, press molding, or roll molding, to form a film, and then the layers can be laminated to obtain an interlayer film. If the interlayer film consists of multiple layers, co-extrusion is preferred for extrusion molding. Among the above methods, it is preferable to mold the interlayer film by extrusion molding. By employing extrusion molding, wide interlayer films can be manufactured efficiently. Furthermore, as shown in the method for manufacturing the laminate described later, the interlayer of the present invention may consist of multiple interlayers arranged between two substrates and integrated between the two substrates to form a single interlayer.

[0067] The interlayer may be manufactured 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 other 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 is effectively reduced, making it possible to easily knead the resin composition in an extruder or the like. The additive contained in mixture (A) may be one or more selected from the above-mentioned additives, and preferably contains at least one of a silane coupling agent, an ultraviolet absorber, and an antioxidant, but may also contain other additives. The form of mixture (A) is not particularly limited, but is typically in the form of particles such as pellets.

[0068] The interlayer is preferably used by being placed between two substrates, and more preferably by being used as a laminate, as will be described later. Furthermore, the interlayer may be placed between two components, i.e., two substrates, and used to bond the two substrates together. The interlayer is particularly preferably a laminated glass interlayer used in laminated glass. The two substrates may be the same or different.

[0069] <Laminate> The laminate of the present invention has an interlayer and two substrates, with the interlayer being placed between the two substrates. The two substrates may be the same or different. In the laminate, the two substrates are preferably bonded together via the interlayer. In the laminate, the interlayer placed between the two substrates may be one, or multiple interlayers may be placed and integrated between the two substrates to form a single interlayer. By placing multiple interlayers between the two substrates, even when it is necessary to increase the thickness of the interlayer between two glass sheets, such as in laminated glass for building structures, this can be accommodated with an interlayer of a general-purpose thickness. The multiple interlayers are preferably integrated between the substrates, and the two substrates are preferably bonded together via the integrated interlayer. The total thickness of the interlayer between the substrates in the laminate is not particularly limited, but for example, it is 0.2 mm or more and 7.6 mm or less, preferably 0.6 mm or more and 4.5 mm or less, and more preferably 1.5 mm or more and 3.6 mm or less.

[0070] A separate layer may be provided between the interlayer and the substrate, but it is preferable that no separate layer is provided and the interlayer is in direct contact with the substrate. Furthermore, when using multiple interlayers, a separate layer may be provided between the multiple interlayers, but it is preferable that no separate layer is provided and the interlayers are directly bonded to each other to form a single integrated interlayer. Examples of the separate layer include resin films other than the interlayer of the present invention described above.

[0071] The substrates used in laminates include resin films and glass, but glass is preferred among these. By using glass as both substrates in a laminate, the laminate becomes laminated glass.

[0072] Examples of resin films used as substrates include polyester resin films such as (meth)acrylic resin films, polycarbonate films, polyethylene terephthalate (PET) films, and polyethylene naphthalate (PEN) films, as well as polyolefin resin films such as polyethylene films and polypropylene films, cyclic polyolefin (COP) films, triacetylcellulose (TAC) films, polyethersulfone (PES) resin films, and polyimide resin films. The resin film may consist of a single layer or two or more layers laminated together. Functional layers such as a hard coat layer may be provided on the surface of the resin film as appropriate, and electrodes, sensors, etc., may be attached. The thickness of the resin film used as a substrate is not particularly limited, but is preferably 30 μm or more, more preferably 50 μm or more, and also, for example, 1 mm or less, but preferably 500 μm or less, and more preferably 450 μm or less.

[0073] Furthermore, glass sheets can be used as the glass. The glass sheets can be either inorganic glass or organic glass, but inorganic glass is preferred. Inorganic glass is not particularly limited, but examples include clear glass, float glass, tempered glass such as tempered float glass, colored glass, polished glass, patterned glass, wired glass, reinforced glass, ultraviolet absorbing glass, infrared reflective glass, infrared absorbing glass, and green glass. Among these, float glass is preferred from the viewpoint of versatility, and tempered glass is preferred from the viewpoint of high resistance to high-speed impact. As for organic glass, what is generally called resin glass is used, and is not particularly limited, but examples include organic glass composed of polycarbonate sheets, polymethyl methacrylate sheets, polyester sheets, etc. The two glass sheets may be made of the same material or different materials. For example, one may be inorganic glass and the other may be organic glass, but it is preferable that both glass sheets are either inorganic glass or organic glass. The thickness of each of the above-mentioned glass layers is not particularly limited, but is, for example, 0.5 mm to 20 mm, preferably 1 mm to 15 mm, more preferably 2 mm to 12 mm, and even more preferably 3 mm to 10 mm. Setting the glass thickness above a certain value makes it easier to improve the resistance of the laminate to high-speed impacts. Also, setting the thickness below the above upper limit prevents the laminate from becoming unnecessarily thick.

[0074] In one embodiment of the present invention, the laminate preferably has a Pammel value of 6 or higher from the viewpoint of preventing delamination, foaming, etc. A Pammel value of 7 or higher is more preferable, and 8 or higher is even preferable. The Pammel value is 9 or lower. The Pammel value is a value measured relative to the laminate. The measurement conditions for the Pammel value are as described above, and the details of the test method are as described in the examples. The glass transition temperature of the interlayer is as described above, and a detailed explanation thereof is omitted.

[0075] (Method for Manufacturing Laminates) The laminate of the present invention can be manufactured, for example, by preparing two substrates and one or more interlayer films, placing one or more interlayer films between the two substrates, and then pressing them together. If the laminate has another layer other than the interlayer film of the present invention, a resin film or the like that constituting the other layer may be placed together with the interlayer between the two substrates. The pressing is not particularly limited, but it is preferable to press while heating. Alternatively, pre-bonding may be performed at a relatively low pressure and temperature, and then the final bonding may be performed at a higher pressure, temperature, or both than the pre-bonding. When multiple interlayer films are placed between two substrates, it is preferable to integrate the multiple interlayer films during the pressing process.

[0076] Furthermore, in the case of laminated glass, for example, one or more interlayer films are placed between two sheets of glass, and the air remaining between the two sheets of glass and the interlayer film 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 two sheets of glass, it is preferable to integrate the multiple interlayer films by either pre-bonding or complete bonding.

[0077] The interlayers and laminates of the present invention can be used in a variety of fields, including electronic devices such as displays, 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. In vehicles and building structures, it is preferable to use laminated glass. In vehicle applications, it is often used as window glass; for example, in automobiles, it may be used as the windshield, rear window, or side window. In building structures, it may be used as window glass, glass floor, curtain wall, etc. Laminated glass may, for example, be made into large sheets or used as structural glazing.

[0078] 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.

[0079] The various physical properties were measured and evaluated as follows.

[0080] [Interlayer Thickness] The thickness of the interlayer was measured using an Olympus DSX500 microscope and an average of 10 points.

[0081] [Content and degree of neutralization of each constituent unit] The amount (mol%) of each constituent unit in the ethylene-(meth)acrylic acid copolymer and its ionomer resin is determined after the hydrochloric acid treatment described below. １The composition was determined by 1H-NMR and IR measurements. For the measurement of the content and degree of neutralization of each constituent unit, if the interlayer film contained an ethylene-unsaturated carboxylic acid copolymer and its ionomer resin, the sample used was a mixture obtained by mixing these in the proportions used in each interlayer film. If the interlayer film did not contain an ethylene-unsaturated carboxylic acid copolymer and only an ionomer resin was used, the ionomer resin used in each interlayer film was used as the sample. (Hydrochloric acid treatment) 100 mg of the sample, freeze-dried using JFC-2000 (manufactured by Nippon Analytical Industry Co., Ltd.), was mixed with 500 μL of ethanol and 1 mL of hydrochloric acid and stirred at 60°C for 48 hours. Afterward, it was washed three times with ultrapure water to remove the hydrochloric acid and dried by heating.

[0082] (Degree of Neutralization) The degree of neutralization was determined by IR measurement of the sample before and after hydrochloric acid treatment. 1460 cm⁻¹ before and after hydrochloric acid treatment －１ Based on the peak height of methylene, 1700 cm －１ The peak height of the carboxylic acid was calculated using the following formula. In the following formula, the denominator is 1700 cm in the sample after hydrochloric acid treatment. －１ Peak height: 1460 cm －１ The peak height of the molecule is 1700 cm in the sample before hydrochloric acid treatment. －１ Peak height: 1460 cm －１ This represents the peak height.

[0083] ( １ (H-NMR measurement) After hydrochloric acid treatment, the sample was dissolved in a solvent (tetrachloroethane:dimethyl sulfoxide = 5:2) to a concentration of approximately 1-3% by mass to prepare the measurement solution. １¹H-NMR measurements were performed (instrument: AVANCE 400 (PRODIGY), spectrometer: AVANCE III HD). The measurement conditions were 8 cumulative measurements at a temperature of 120°C. In the analysis, the integral value of H originating from the methyl group of methacrylic acid was used as the reference value, set to 3.00. At that time, the total mol% of constituent units (B) and (C) and the content (mol%) of constituent unit (A) derived from ethylene were calculated from the integral intensity ratio of the H peaks originating from methylene that appear between 1.15 and 1.62 ppm. Furthermore, the respective content (mol%) of constituent units (B) and (C) was calculated from the degree of neutralization.

[0084] [Pammel Value] 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 part of the laminated glass (150 mm vertical x 150 mm horizontal area) 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 value of the surface and the Pammel value of the back surface. The Pammel value is a value that examines the degree of adhesion between the interlayer and the glass plate, and is defined by the degree of exposure (area %) of the film after partial delamination of the glass, as defined in Table 1. A larger Pammel value indicates higher adhesion of the interlayer.

[0085] Based on the Panmel values ​​measured as described above, the following evaluations were made. Note that a higher Panmel value indicates better adhesion. (Evaluation) A: Panmel value of 6 or higher B: Panmel value less than 6

[0086] [Bending Stiffness] The bending stiffness of laminated glass was evaluated using the test method schematically shown in Figure 1. As the measuring device, an Instron "Type 5965 Universal Tester" fitted with a three-point bending test fixture was used. The measurement conditions were as follows: the distance D1 between the supports was 13.2 cm, the sample length D2 was 20 cm, and the width was 8 cm. Deformation was applied to the laminated glass 20 in the direction F at a displacement rate of 1 mm / min, and the stress was measured when either a displacement of 0.5 mm was reached or a force of 500 N was applied, and the bending stiffness was calculated. When calculating the bending stiffness, data with an indentation depth of 0.2 mm or more was used. The bending stiffness was measured in both a 25°C environment and a 50°C environment. Three samples were prepared at each level, and the bending stiffness of each was measured, and the arithmetic mean of the three was used. The bending stiffness (N / mm) is the slope of the straight line on a graph created with indentation depth (mm) on the horizontal axis and load (N) on the vertical axis. The laminated glass obtained in each example and comparative example was cured for one week after manufacturing by being left in an environment of 23°C and 50% RH before its bending stiffness (N / mm) was measured.

[0087] [Yellowness YI] For each example and comparative example, the laminated glass obtained was measured using a spectrophotometer (Hitachi High-Tech Corporation "U-4100") in accordance with JIS K7105, and the YI value (yellowness, yellow index) of the obtained laminated glass was measured by transmission. The result was divided by the thickness d (mm) of the interlayer and evaluated according to the following evaluation criteria. (Evaluation) A: YI / d is less than 2.0 B: YI / d is 2.0 or more

[0088] [Haze] For each example and comparative example, the laminated glass obtained was measured at 25°C in accordance with JIS K6714 and evaluated based on the following evaluation criteria. A Haze Meter "HM-150N" manufactured by Murakami Color Co., Ltd. was used for measurement. (Evaluation) A: Haze is less than 0.6% B: Haze is 0.6% or more

[0089] [UV Cut Rate] For the laminated glass obtained in each example and comparative example, the UV cut rate was determined by calculating the ultraviolet transmittance (%) at wavelengths of 300 nm to 380 nm using the following formula (I). The ultraviolet transmittance was calculated using a spectrophotometer (for example, Hitachi High-Tech Corporation's "U-4150") in accordance with JIS A 5759:2016. In equation (I), T UV is ultraviolet transmittance, T(λ) is spectral transmittance (%), U λ Δλ is the weighting factor for ultraviolet light. The UV cut rate (%) was calculated from the ultraviolet transmittance (%) obtained by formula (I) using "100 - ultraviolet transmittance (%)". (Evaluation) A: UV cut rate of 90% or more B: UV cut rate of less than 90%

[0090] [Overall Judgment] For each evaluation of Pammel value, yellowness (YI), haze, and UV cut rate, the overall judgment was "A" if all evaluation results were "A", and "B" if at least one evaluation result was "B".

[0091] The components used in the following examples and comparative examples were as follows:

[0092] <Resin> Ionomer 1: Ionomer resin obtained by neutralizing an ethylene-methacrylic acid copolymer with magnesium ions. In the ionomer resin, constituent units derived from ethylene (A) = 92.6 mol%, constituent units derived from neutralized methacrylic acid (B) = 5.3 mol%, constituent units derived from methacrylic acid (constituent units with unneutralized carboxylic acid) (C) = 2.1 mol%, degree of neutralization = 72%. Ionomer 2: Ionomer resin obtained by neutralizing an ethylene-methacrylic acid copolymer with sodium ions. In the ionomer resin, constituent units derived from ethylene (A) = 91.2 mol%, constituent units derived from neutralized methacrylic acid (B) = 6.4 mol%, constituent units derived from methacrylic acid (constituent units with unneutralized carboxylic acid) (C) = 2.4 mol%, degree of neutralization = 73%. Ionomer 3: An ionomer resin obtained by neutralizing an ethylene-methacrylic acid copolymer with magnesium ions. In the ionomer resin, the constituent units derived from ethylene (A) = 92.9 mol%, the constituent units derived from neutralized methacrylic acid (B) = 3.8 mol%, the constituent units derived from methacrylic acid (constituent units with unneutralized carboxylic acid) (C) = 3.3 mol%, and the degree of neutralization = 54%. Ionomer 4: An ionomer resin obtained by neutralizing an ethylene-methacrylic acid copolymer with magnesium ions. In the ionomer resin, the constituent units derived from ethylene (A) = 92.9 mol%, the constituent units derived from neutralized methacrylic acid (B) = 3.3 mol%, the constituent units derived from methacrylic acid (constituent units with unneutralized carboxylic acid) (C) = 3.8 mol%, and the degree of neutralization = 46%. EMAA: Ethylene-methacrylic acid copolymer, with ethylene-derived constituent units (A) = 92.6 mol%, and methacrylic acid-derived constituent units (constituent units with unneutralized carboxylic acid) (C) = 7.4 mol%.

[0093] <UV absorbers> ・UV absorbers having a benzotriazole structure, such as "RIASORB UV-928" (manufactured by Rianlon), and UV absorbers with the structure represented by the following formula (3). In the table, it is indicated as "UV-928".

[0094] - A UV absorber having a benzotriazole structure, "RIASORB UV-P" (manufactured by Rianlon), is a UV absorber with the structure represented by the following formula. In the table, it is indicated as "UV-P".

[0095] - Benzophenone-based UV absorber, "SEESORB 107" (manufactured by Cipro Chemical Co., Ltd.), a UV absorber with the structure represented by the following formula.

[0096] - A UV absorber having a benzotriazole structure, "RIASORB UV-234" manufactured by Rianlon, is a compound represented by the following formula (2), and is indicated as "UV-234" in the table.

[0097] - A triazine-containing ultraviolet absorber, "RIASORB UV-1164" manufactured by Rianlon, has a structure represented by the following formula, and is indicated as "UV-1164" in the table.

[0098] - A UV absorber having a triazine structure, "RIASORB UV-460" manufactured by Rianlon, is a UV absorber with a structure represented by the following formula, and is indicated as "UV-460" in the table.

[0099] <Silane Coupling Agents> • "KBM-602" (manufactured by Shin-Etsu Silicone Co., Ltd.), N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane • "KBE-402" (manufactured by Shin-Etsu Silicone Co., Ltd.), 3-glycidoxypropylmethyldiethoxysilane

[0100] [Example 1] Ionomer resin 1, EMMA, ultraviolet absorber (UV-928), and silane coupling agent (KBM-602) were put into an extruder in the proportions shown in Table 2, kneaded at 170°C, and extruded to obtain an interlayer film with a thickness of 0.76 mm and a width of 1 m. Next, laminated glass was prepared using the obtained interlayer film as follows, and various measurements were performed.

[0101] (Preparation of laminated glass for Pammel value measurement) Two pieces of clear glass (300 mm long x 150 mm wide) with a thickness of 2.75 mm (measured value, nominal value is 3 mm) in accordance with JIS R3202 (2011) were prepared, along with one interlayer measuring 30 cm long x 15 cm wide. The interlayer was sandwiched between the two pieces of clear glass to obtain a laminated intermediate. This laminated intermediate was placed in a rubber bag and degassed at a vacuum of 0.08 MPa for 20 minutes. Then, while still degassed, it was transferred to an oven and held at 90°C for 30 minutes to vacuum press and temporarily bond the laminated intermediate. The temporarily bonded laminated intermediate was pressed in an autoclave at 140°C and a pressure of 1.3 MPa for 20 minutes to obtain laminated glass with the two pieces of glass bonded together by the interlayer. In the fabrication of the laminated glass, the top surface of each float glass plate (the surface opposite the tin surface) was adjusted to become the bonding surface with the interlayer.

[0102] (Preparation of laminated glass for bending stiffness measurement) Two pieces of float glass (manufactured by Sanshiba Glass Co., Ltd.) measuring 20 cm in length, 8 cm in width, and 2.75 mm in thickness were prepared, along with one interlayer measuring 20 cm in length, 8 cm in width. The interlayer was sandwiched between the two pieces of float glass to obtain a laminated intermediate. Subsequently, laminated glass was prepared using the same method as for the preparation of laminated glass for measuring the Pammel value described above, and the bending stiffness was measured using the obtained laminated glass. In the preparation of the laminated glass for bending stiffness measurement, the top surface of each piece of float glass (the surface opposite the tin side) was adjusted to become the bonding surface with the interlayer.

[0103] (Preparation of laminated glass for measuring yellowness YI) Two clear glass sheets (5 cm long x 5 cm wide x 2.0 mm thick) and interlayer films prepared in accordance with JIS R3202 (2011) for each example and comparative example were prepared. The interlayer film was sandwiched between the two clear glass sheets 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, while still degassed, it was transferred to an oven and held at 90°C for 30 minutes to vacuum press and temporarily bond the laminate. The temporarily bonded 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 / glass plate.

[0104] (Preparation of laminated glass for haze value measurement) Laminated glass was prepared using the same method as the laminated glass for yellowness YI measurement described above.

[0105] (Preparation of laminated glass for UV cut rate measurement) Laminated glass was prepared using the same method as the laminated glass for yellowness YI measurement described above.

[0106] [Examples 2-17, Comparative Examples 1-16] Interlayer films and laminated glass were prepared in the same manner as in Example 1, except that the types and amounts of resin, UV absorber, and silane coupling agent used were changed as shown in Tables 2-3, and various measurements were performed.

[0107]

[0108]

[0109] The interlayers of each example contain 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. The content of the ultraviolet absorber is 0.04 to 0.18% by mass, and the content of constituent units having an unneutralized carboxylic acid is 2.5 to 4.3 mol%. The interlayers of each example that satisfy the requirements of the present invention have a high Pammel value, thus exhibiting excellent adhesion, high transparency due to low yellowness and haze, and excellent UV cut rate. Furthermore, Example 3 is an example using a compound having a benzotriazole structure with a branched alkyl group, and it was confirmed that the haze value was lower compared to Example 10, which uses a compound having a benzotriazole structure without a branched alkyl group. Examples 11 to 13 are examples in which only ionomer resin is used as the resin (100% ionomer resin), but by adjusting the content of the ultraviolet absorber and the content of constituent units having an unneutralized carboxylic acid within a predetermined range, an interlayer with high adhesion, high UV cut rate, and good transparency was obtained. On the other hand, the interlayer films of Comparative Examples 1, 6-11, 14, and 15, which either did not contain UV absorbers or contained them in small amounts, had poor UV protection. Comparative Examples 2-5 and 12-13 and 16, which had high UV absorber content, had high yellowness and poor transparency. Furthermore, the interlayer films of Comparative Examples 3, 6, and 12-13, which had low content of constituent units containing unneutralized carboxylic acids, had low Pammel values ​​and poor adhesion, while the interlayer film of Comparative Example 11, which had a high content of constituent units containing unneutralized carboxylic acids, had a high Pammel value but high yellowness and haze and poor transparency.

Claims

1. An interlayer 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, wherein the content of the ultraviolet absorber is 0.04 to 0.18% by mass, and the content of unneutralized carboxylic acid-containing structural units based on the total amount of resin containing structural units derived from unsaturated carboxylic acids is 2.5 to 4.3 mol%.

2. The interlayer according to claim 1, wherein the compound having the benzotriazole structure includes a compound represented by the following general formula (I). (In the above formula, R １ R is an organic group having 4 or more carbon atoms. ２ ~R ８ Each of these is independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms.

3. The interlayer according to claim 1, wherein the compound having the benzotriazole structure comprises any of the compounds of the following formulas (2) to (4).

4. The intermediate film according to any one of claims 1 to 3, wherein the compound having the benzotriazole structure includes the compound of the following formula (3).

5. The intermediate film according to any one of claims 1 to 3, wherein the content of the constituent unit having the unneutralized carboxylic acid is 2.5 to 3.5 mol%.

6. An interfilm according to any one of claims 1 to 3, comprising a silane coupling agent.

7. An interlayer according to any one of claims 1 to 3, wherein the Pammel value is 6 or greater.

8. The interfilm according to any one of claims 1 to 3, wherein the ionomer resin is a resin neutralized with magnesium ions.

9. The interlayer according to any one of claims 1 to 3, wherein the bending rigidity at 50°C of the laminated glass obtained by bonding two 2.75 mm thick glass sheets with an interlayer in between is 700 N / mm or more.

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