Intermediate film, laminate, and laminated glass

Abstract

This intermediate film includes an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer.　The present invention makes it possible to provide an intermediate film that can suppress yellowing over time due to light and heat.

Description

Interlayers, laminates, and laminated glass

[0001] The present invention relates to an interlayer film used in laminated glass, a laminate including the interlayer film, and laminated glass.

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

[0003] Ionomer resins have been used in interlayer films for laminated glass in some cases. Known ionomer resins used in interlayer films for laminated glass include ethylene-unsaturated carboxylic acid copolymers, such as ethylene-(meth)acrylic acid copolymers, in which at least some of the carboxyl groups in the side chains are crosslinked between molecular chains by metal cations (see, for example, Patent Documents 1 to 4).

[0004] International Publication No. WO 2022 / 270545 International Publication No. WO 2022 / 065146 JP 2014-58409 A International Publication No. WO 2019 / 054363

[0005] When laminated glass is used in buildings, for example, it is required to suppress yellowing over time due to light and heat. When the above-mentioned ionomer resin is used in an interlayer film, although it has excellent strength and transparency, the ionomer resin itself does not have ultraviolet absorption ability, so it is necessary to add an ultraviolet absorber. However, according to the inventors' studies, it was found that when an ultraviolet absorber was added to the ionomer resin, the edges of the interlayer film yellowed over time due to heat (edge ​​yellowing). To solve this problem, the inventors attempted to use an ultraviolet absorber in combination with an antioxidant, but yellowing over time due to light was confirmed in a light irradiation test using a xenon light source.

[0006] Therefore, an object of the present invention is to provide an interlayer film containing an ionomer resin that can suppress yellowing over time due to light and heat.

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using an interlayer film containing an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer, and have completed the present invention as described below. That is, the present invention provides the following [1] to

[23] .

[0008] [1] An interlayer film comprising an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer. [2] The interlayer film according to [1] above, wherein the phenolic antioxidant has a structure including a phenol group having a t-butyl group at at least one ortho position. [3] The interlayer film according to [1] or [2] above, wherein the N-C hindered amine light stabilizer has a structure represented by formula (1). (In formula (1), *1 and *2 each represent a bond, and *1 represents a bond bonding to a carbon atom.) [4] The interlayer film according to any one of [1] to [3] above, wherein the content of the phenolic antioxidant is 0.05 parts by mass or more and 0.50 parts by mass or less relative to 100 parts by mass of the ionomer resin. [5] The interlayer film according to any one of [1] to [4] above, wherein the content of the N-C hindered amine light stabilizer is 0.01 parts by mass or more and 0.50 parts by mass or less relative to 100 parts by mass of the ionomer resin. [6] The interlayer film according to any one of [1] to [5] above, wherein the content of the antioxidant other than the phenolic antioxidant is 0.30 parts by mass or less relative to 100 parts by mass of the ionomer resin. [7] The interlayer film according to any one of [1] to [6] above, wherein the content of the hindered amine light stabilizer other than the N-C hindered amine light stabilizer is 0.30 parts by mass or less per 100 parts by mass of the ionomer resin. [8] The interlayer film according to any one of [1] to [7] above, wherein the additive having the highest melting point among the additives contained in the interlayer film has a melting point lower than 180°C. [9] The interlayer film according to any one of [1] to [8] above, wherein the ultraviolet absorber is a compound having a benzotriazole structure.

[10] The interlayer film according to any one of [1] to [9] above, wherein the interlayer film contains a silane coupling agent.

[11] The interlayer film according to any one of [1] to

[10] above, wherein the ionomer resin contains a structural unit (A) derived from (meth)acrylic acid, a structural unit (B) derived from a neutralized (meth)acrylic acid, and a structural unit (C) derived from ethylene.

[12] The interlayer film according to

[11] above, wherein the ionomer resin has a total content of the structural units (A) and (B) of 10% by mass or more and 25% by mass or less, based on the total amount of the structural units constituting the ionomer resin.

[13] The interlayer film according to

[11] or

[12] above, wherein the ionomer resin has a content of the structural unit (B) of 4% by mass or more and 17.5% by mass or less, based on the total amount of the structural units constituting the ionomer resin.

[14] The interlayer film according to any one of

[11] to

[13] above, wherein the structural unit (B) in the ionomer resin contains sodium, zinc, or magnesium.

[15] The interlayer film according to any one of [1] to

[14] above, wherein a laminated glass made from two 2.0 mm thick clear glass sheets and the interlayer film has a haze value of 2% or less.

[16] A laminate comprising the interlayer film according to any one of [1] to

[15] above and a pair of substrates, the interlayer film being disposed between the pair of substrates.

[17] The laminate according to

[16] above, wherein the substrates are a pair of substrates selected from the group consisting of organic material substrates and inorganic material substrates.

[18] The laminate according to

[16] or

[17] above, wherein at least one of the pair of substrates is the organic material substrate, and the organic material substrate is at least one selected from the group consisting of a polarizing film, a polyethylene terephthalate film, a polycarbonate plate, and a (meth)acrylic plate.

[19] Laminated glass comprising the laminate according to any one of

[16] to

[18] above.

[20] A display comprising the laminate according to any one of

[16] to

[18] above.

[21] A building comprising the laminate according to any one of

[16] to

[18] above.

[22] A resin composition comprising an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer.

[23] A masterbatch comprising an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer.

[0009] An object of the present invention is to provide an interlayer film containing an ionomer resin that can suppress yellowing over time due to light and heat.

[0010] The present invention will be described in detail below with reference to embodiments. [Interlayer film] The interlayer film of the present invention contains an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer. The interlayer film of the present invention is an interlayer film containing an ionomer resin, but by using an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer in combination, yellowing over time due to light and heat can be suppressed. Each component contained in the interlayer film of the present invention will be described in detail below.

[0011] <Ionomer Resin> The interlayer film of the present invention contains an ionomer resin. The inclusion of an ionomer resin improves the mechanical strength and transparency of the interlayer film. Examples of ionomer resins include ionomer resins of ethylene-unsaturated carboxylic acid copolymers. Ionomer resins are typically resins obtained by neutralizing ethylene-unsaturated carboxylic acid copolymers with metal ions. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, 2-ethylacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, fumaric anhydride, itaconic anhydride, monomethyl maleate, and monoethyl maleate. In the ionomer resin, the unsaturated carboxylic acid may be used alone or in combination of two or more. 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. 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 sodium, magnesium, and zinc is preferred, magnesium or zinc is more preferred, and magnesium is particularly preferred. Metal ions may be used alone or in combination. Using at least one of magnesium and zinc, particularly magnesium, as the metal ion forms an appropriate crosslinked structure, which facilitates increasing the glass transition temperature of the interlayer film and increasing its mechanical strength. Note that (meth)acrylic acid means at least one of methacrylic acid and acrylic acid, and the same applies to similar terms below.

[0012] When the ionomer resin is an ethylene-unsaturated carboxylic acid copolymer, it typically contains a structural unit (A) derived from an unsaturated carboxylic acid, a structural unit (B) derived from a neutralized product of an unsaturated carboxylic acid, and a structural unit (C) derived from ethylene. In particular, when the ionomer resin is an ethylene-(meth)acrylic acid copolymer, it typically contains a structural unit (A) derived from (meth)acrylic acid (hereinafter also referred to as structural unit (A)), a structural unit (B) derived from a neutralized product of (meth)acrylic acid (hereinafter also referred to as structural unit (B)), and a structural unit (C) derived from ethylene. By containing these structural units (A), (B), and (C), the ionomer resin is likely to have excellent mechanical strength and transparency.

[0013] The monomer constituting the structural unit (A) is not particularly limited as long as it is an unsaturated carboxylic acid, but is preferably at least one of acrylic acid and methacrylic acid. Among these, methacrylic acid is more preferred from the viewpoints of mechanical strength and adhesiveness. The structural unit (A) is a structural unit that has not been neutralized with a metal ion. The structural unit (B) is a neutralized product of a structural unit derived from the above-mentioned unsaturated carboxylic acid, and is preferably a structural unit derived from a neutralized product of at least one of acrylic acid and methacrylic acid, and more preferably a structural unit derived from a neutralized product of methacrylic acid. The structural unit (B) is a structural unit in which the hydrogen ion of the carboxy group in the unsaturated carboxylic acid is substituted with a metal ion. That is, the unsaturated carboxylic acid neutralized product in the structural unit (B) is a metal salt of the unsaturated carboxylic acid. The metal ion in the metal salt is as described above, but is preferably sodium, zinc, or magnesium, more preferably at least one of magnesium and zinc, and particularly preferably magnesium. Therefore, the structural unit (B) preferably contains sodium, zinc, or magnesium, more preferably at least one of magnesium and zinc, and particularly preferably magnesium.

[0014] In the ionomer resin, the total content of the structural units (A) and (B) is preferably 10% by mass or more and 25% by mass or less, based on the total amount of the structural units constituting the ionomer resin. When the total content of the structural units (A) and (B) is 10% by mass or more, the transparency, heat resistance, mechanical strength, etc. of the interlayer film can be improved. Furthermore, when the total content is 25% by mass or less, the flexibility, processability, adhesiveness, etc. can be improved. The total content of the structural units (A) and (B) is more preferably 12% by mass or more and 23% by mass or less, and even more preferably 15% by mass or more and 20% by mass or less.

[0015] In the ionomer resin, the content of the structural unit (B) is preferably 4% by mass or more and 17.5% by mass or less, based on the total amount of structural units constituting the ionomer resin. When the content of the structural unit (B) is 4% by mass or more, the degree of crosslinking of the ionomer resin is increased, and mechanical strength is easily increased. Furthermore, when the content of the structural unit (B) is 4% by mass or more, transparency and heat resistance are also easily increased. Furthermore, by setting the content of the structural unit (B) to 17.5% by mass or less, the flexibility, adhesion, mechanical strength, processability, etc. of the interlayer film are easily improved. The content of the structural unit (B) in the ionomer resin is more preferably 6% by mass or more and 17% 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. The content of the structural unit (B) in the ionomer resin is preferably 6% by mass or more, more preferably 7% by mass or more, even more preferably 9% by mass or more, and still more preferably 10% by mass or more, and is preferably 17% by mass or less, more preferably 16% by mass or less, even more preferably 14% by mass or less, even more preferably 13% by mass or less, and still more preferably 12.5% ​​by mass or less.

[0016] The content of the ethylene-derived structural unit (C) is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, based on the total amount of structural units constituting the ionomer resin, from the viewpoint of easily increasing the impact resistance of the ionomer resin. Furthermore, from the viewpoints of transparency, mechanical strength, and moldability, the content of the ethylene-derived structural unit (C) is preferably 90% by mass or less, more preferably 89% by mass or less, even more preferably 88% by mass or less, and even more preferably 85% by mass or less.

[0017] In the ionomer resin, the content of the structural unit (A) is not particularly limited, but is preferably 3% by mass or more and 15% by mass or less, more preferably 4% by mass or more and 10% by mass or less, even more preferably 5% by mass or more and 9% by mass or less, and still more preferably 4% by mass or more and 8% by mass or less, based on the total amount of the structural units constituting the ionomer resin.

[0018] The ionomer resin may be a copolymer of ethylene and a (meth)unsaturated carboxylic acid neutralized with a metal ion, or a copolymer of ethylene, an unsaturated carboxylic acid, and a monomer other than ethylene and the unsaturated carboxylic acid neutralized with a metal ion. Thus, in a preferred embodiment, the ionomer resin may contain, in addition to the structural units (A), (B), and (C), structural units other than the structural units (A), (B), and (C) (hereinafter also referred to as "other structural units").

[0019] Other structural units include structural units (D) derived from alkyl (meth)acrylates. The presence of the structural unit (D) makes it possible to adjust the glass transition temperature (Tg) of the ionomer resin, for example. Examples of alkyl (meth)acrylates include alkyl (meth)acrylates having approximately 1 to 10 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl. From the viewpoint of not lowering the glass transition temperature of the interlayer film more than necessary, the content of the structural unit (D) derived from alkyl (meth)acrylate is preferably 15% by mass or less, more preferably 8% by mass or less, even more preferably 4.5% by mass or less, and even more preferably 2% by mass or less. Furthermore, from the viewpoint of increasing the mechanical strength at high temperatures without lowering the glass transition temperature, the lower the content of the structural unit (D), the better; it may be 0% by mass or more; and it is preferable that the ionomer resin does not contain the structural unit (D).

[0020] In addition, isobutyl (meth)acrylate is generally preferably used as the alkyl (meth)acrylate in the ionomer resin, but in the present invention, it is preferable that the ionomer resin does not contain any structural units derived from isobutyl (meth)acrylate, or contains only a small amount of such units. Therefore, the content of structural units derived from isobutyl (meth)acrylate is preferably 15% by mass or less, more preferably 8% by mass or less, even more preferably 4.5% by mass or less, and even more preferably 2% by mass or less. In addition, the content of structural units derived from isobutyl (meth)acrylate may be 0% by mass or more, and it is preferable that the ionomer resin does not contain any structural units derived from isobutyl (meth)acrylate.

[0021] Furthermore, the ionomer resin may contain, as other structural units, structural units other than the structural units (A), (B), (C), and (D), and may have, for example, structural units derived from vinyl esters such as vinyl acetate and vinyl propionate.

[0022] In the present invention, the degree of neutralization of the ionomer resin is, for example, 30% or more. From the viewpoint of increasing mechanical strength, it is preferably greater than 40%, more preferably 42% or more, even more preferably 45% or more, and even more preferably 50% or more. Increasing the degree of neutralization of the ionomer resin facilitates increasing the mechanical strength. In addition, in the present invention, it is preferable that the structural unit (B) contains at least one of magnesium and zinc (particularly magnesium) and that the degree of neutralization is increased from the viewpoint of improving mechanical strength. The degree of neutralization of the ionomer resin is not particularly limited, but from the viewpoint of improving the flexibility, adhesion, mechanical strength, processability, etc. of the interlayer film, it is preferably 95% or less, more preferably 90% or less, even more preferably 80% or less, and even more preferably 75% or less. The degree of neutralization of the ionomer resin refers to the percentage (%) of carboxyl groups neutralized with metal ions among all carboxyl groups contained in the ionomer resin.

[0023] The degree of neutralization of the ionomer resin can be determined by IR measurement before and after the hydrochloric acid treatment. Specific measurement methods are as described in the Examples below. The content of each structural unit in the ionomer resin can be determined by mass spectrometry and １ H-NMR measurement is carried out, and the degree of neutralization can be calculated from the integrated intensity ratio of the hydrogen peaks derived from each monomer.

[0024] The content of the ionomer resin in the interlayer film is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 88% by mass or more, based on 100% by mass of the entire interlayer film. By setting the ionomer resin content within the above lower limit, the rigidity, interlayer adhesion, and other properties of the resulting laminated glass can be improved. Furthermore, the content of the ionomer resin in the interlayer film may be, for example, 99.99% by mass or less or 99.9% by mass or less, based on 100% by mass of the entire interlayer film, in order to ensure that a certain amount or more of additives is contained. Furthermore, when the ionomer resin in the interlayer film contains other resin components, the content of the ionomer resin in the interlayer film is preferably a certain amount or less, for example, 98.4% by mass or less, 97.4% by mass or less, or 96.4% by mass or less.

[0025] The method for producing the ionomer resin is not particularly limited, and the ionomer resin can be produced by a known method. For example, the ionomer resin can be produced by radically copolymerizing each monomer component under high temperature and high pressure to obtain an ethylene-unsaturated carboxylic acid copolymer, and then reacting the copolymer with a metal compound.

[0026] <Other Resin Components> The interlayer film of the present invention may contain other resin components in addition to the ionomer resin. The inclusion of other resin components in the interlayer film of the present invention facilitates improved formability, such as extrusion. The other resin components are preferably resins compatible with the ionomer resin. From the viewpoint of compatibility with the ionomer resin, the other resin components are preferably ethylene-unsaturated carboxylic acid copolymers. Here, the unsaturated carboxylic acids used in the ethylene-unsaturated carboxylic acid copolymers are as described above, with (meth)acrylic acid being preferred, and methacrylic acid being more preferred. Furthermore, from the viewpoints of compatibility and extrusion, the other resin components are preferably copolymers of the same type as the copolymer used in the ionomer resin, and more preferably resins prior to neutralization with metal ions to obtain the ionomer resin. Therefore, when the ionomer resin is an ionomer resin of an ethylene-(meth)acrylic acid copolymer, the other resin components are preferably ethylene-(meth)acrylic acid copolymers. When the ionomer resin is an ionomer resin of an ethylene-methacrylic acid copolymer, the other resin component is preferably an ethylene-methacrylic acid copolymer.

[0027] When other resin components are used, the content of the other resin components is preferably 1.5% by mass or more and 25% by mass or less, relative to 100% by mass of the entire interlayer film. By setting the content of the other resin components to 1.5% by mass or more, the viscosity of the ionomer resin is reduced, making it easier to improve extrusion properties. Furthermore, by setting the content to 25% by mass or less, a decrease in mechanical strength can be prevented even when the other resin components are included. The content of the other resin components is more preferably 2.5% by mass or more and 18% by mass or less, and even more preferably 3.5% by mass or more and 11% by mass or less, relative to 100% by mass of the entire interlayer film.

[0028] <Phenol-Based Antioxidant> The interlayer film of the present invention contains a phenol-based antioxidant. A phenol-based antioxidant is an antioxidant having a phenol group in its chemical structure. Among phenol-based antioxidants, from the viewpoint of easily suppressing yellowing of the interlayer film over time due to light and heat when used in combination with an ultraviolet absorber and an N-C hindered amine light stabilizer, a phenol-based antioxidant having a structure with a phenol group having a t-butyl group at at least one ortho-position is preferred. Furthermore, a phenol-based antioxidant having a structure with phenol groups having t-butyl groups at both ortho-positions is more preferred. In other words, a phenol-based antioxidant having a structure with a phenol group having a t-butyl group at at least one ortho-position is a phenol-based antioxidant having a structure represented by the following formula (2): In the above formula (2), a t-butyl group is present at at least one of positions a and b. In addition, in the above formula (2), a t-butyl group is preferably present at both positions a and b.

[0029] The number of structures represented by formula (2) contained in the phenolic antioxidant is preferably one or more, more preferably two or more, and even more preferably three or more, and is usually six or less.

[0030] Examples of commercially available phenolic antioxidants having a structure with a phenol group having a t-butyl group at at least one ortho position include "Irganox 1010," "Irganox 1076," and "Irganox 245" manufactured by BASF, "RIANOX 1010" by Rianlon, and "ADK STAB AO-20," "ADK STAB AO-30," "ADK STAB AO-40," "ADK STAB AO-50," "ADK STAB AO-60," and "ADK STAB AO-80" manufactured by ADEKA. One type of phenolic antioxidant may be used alone, or two or more types may be used in combination.

[0031] The content of the phenolic antioxidant per 100 parts by mass of the ionomer resin is not particularly limited, but is preferably 0.05 parts by mass or more and 0.5 parts by mass or less, and more preferably 0.1 parts by mass or more and 0.4 parts by mass or less. When the content of the phenolic antioxidant is at or above these lower limits, yellowing of the interlayer film over time due to light and heat is more easily suppressed. When the content of the phenolic antioxidant is at or below these upper limits, the effect corresponding to the added amount is easily obtained, use of more than the required amount can be suppressed, and the composition for forming the interlayer film can be easily kneaded.

[0032] The interlayer film of the present invention may contain an antioxidant other than the above-mentioned phenolic antioxidant, but the content thereof is preferably kept low from the viewpoint of suppressing yellowing of the interlayer film over time due to light and heat. The content of the antioxidant other than the phenolic antioxidant per 100 parts by mass of the ionomer resin is preferably 0.3 parts by mass or less, more preferably 0.1 parts by mass or less, and even more preferably 0 part by mass.

[0033] <N-C Hindered Amine Light Stabilizer> The interlayer film of the present invention contains an N-C hindered amine light stabilizer. Hindered amine light stabilizers are known as additives also known as HALS, and are compounds having a hindered amine structure. Here, the hindered amine structure generally has a 2,2,6,6-tetramethylpiperidine skeleton. An N-C hindered amine light stabilizer has a structure in which the nitrogen atom in the hindered amine structure is bonded to a carbon atom other than the carbon atoms constituting the cyclic structure of the hindered amine. More specifically, the N-C hindered amine light stabilizer is a compound having a structure represented by the following formula (1): (In formula (1), *1 and *2 each represent a bond, and *1 represents a bond bonded to a carbon atom.)

[0034] The N-C hindered amine light stabilizer in the present invention may have only one structure represented by the above formula (1), or may have two or more structures represented by the above formula (1), but the number of structures represented by the formula (1) is preferably one or two.

[0035] *1 in formula (1) is not particularly limited as long as it is a bond bonding to a carbon atom, and is, for example, a bond bonding to an organic group R1 having 1 to 10 carbon atoms. The organic group R1 may contain an oxygen atom, a nitrogen atom, or the like. From the viewpoint of suppressing yellowing over time due to light and heat, the organic group R1 is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group.

[0036] In formula (1), *2 represents a bond bonded to any group R2, and examples of R2 include a hydroxyl group and an organic group having 1 to 20 carbon atoms. The organic group having 1 to 20 carbon atoms may be a monovalent to trivalent organic group. For example, when R2 is a divalent or higher organic group, the N-C hindered amine light stabilizer can have a plurality of structures represented by formula (1).

[0037] The number of structures represented by formula (1) in the NC hindered amine light stabilizer may be one, but is preferably two or more, and more preferably two.

[0038] As the N-C hindered amine light stabilizer, commercially available products can be used, and examples thereof include products manufactured by BASF under the names "Tinuvin 765," "Tinuvin PA144," "Tinuvin 292," and "Tinuvin 622." Among these, Tinuvin 765 is preferred. The N-C hindered amine light stabilizers may be used alone or in combination of two or more.

[0039] The content of the N-C hindered amine light stabilizer relative to 100 parts by mass of the ionomer resin is not particularly limited, but is preferably 0.01 parts by mass or more and 0.5 parts by mass or less, more preferably 0.03 parts by mass or more and 0.4 parts by mass or less, and even more preferably 0.07 parts by mass or more and 0.3 parts by mass or less. When the content of the N-C hindered amine light stabilizer is at or above these lower limits, yellowing of the interlayer film over time due to light and heat is more easily suppressed. When the content of the N-C hindered amine light stabilizer is at or below these upper limits, the effect corresponding to the added amount is easily obtained, use of more than the required amount can be suppressed, and the composition for forming the interlayer film can be easily kneaded.

[0040] The interlayer film of the present invention may contain a hindered amine light stabilizer other than the above-mentioned N-C hindered amine light stabilizer, but the content thereof is preferably kept low from the viewpoint of suppressing yellowing of the interlayer film over time due to light and heat. The content of the hindered amine light stabilizer other than the N-C hindered amine light stabilizer per 100 parts by mass of the ionomer resin is preferably 0.3 parts by mass or less, more preferably 0.1 parts by mass or less, and even more preferably 0 part by mass.

[0041] <UV Absorber> The interlayer film of the present invention contains an UV absorber. Examples of UV absorbers include conventionally known UV absorbers such as compounds having a malonic acid ester structure, compounds having an oxalic acid anilide structure, compounds having a benzotriazole structure, compounds having a benzophenone structure, compounds having a triazine structure, compounds having a benzoate structure, and compounds having a hindered amine structure. The UV absorbers may be used alone or in combination of two or more. Among these UV absorbers, compounds having a benzotriazole structure are preferred from the viewpoint of easily suppressing yellowing of the interlayer film over time due to light and heat when used in combination with a phenolic antioxidant and an N-C hindered amine light stabilizer.

[0042] As the compound having a benzotriazole structure, a compound represented by the following formula (3) is preferred from the viewpoint of making it easier to suppress coloration of the interlayer film. (In the above formula, R１ is an organic group having 4 or more carbon atoms, and R ２ ~R ８ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms.

[0043] R in the above formula (3) １ is an organic group having 4 or more carbon atoms. This makes it easier to suppress coloration of the interlayer film. The reason for this is not clear, but １ is a group located at the ortho position of the hydroxyl group in formula (3), and because this is an organic group having 4 or more carbon atoms, it is thought that coordination between the ultraviolet absorber and the metal contained in the ionomer resin can be easily suppressed, and as a result, coloration of the interlayer film can be suppressed.

[0044] R １ From the viewpoint of further suppressing coloration of the interlayer film, R is preferably an organic group having 4 to 20 carbon atoms, and more preferably an organic group having 4 to 10 carbon atoms. １ may contain an oxygen atom, a nitrogen atom, a sulfur atom, etc., but is preferably a hydrocarbon group. １ is preferably a hydrocarbon group having 4 or more carbon atoms, more preferably a hydrocarbon group having 4 to 20 carbon atoms, and even more preferably a hydrocarbon group having 4 to 10 carbon atoms. １ Preferably, R has either a quaternary carbon atom or an aromatic ring, or both. It is presumed that such a structure makes it easier to suppress coordination between the ultraviolet absorber and the metal contained in the ionomer resin, and as a result, coloration of the interlayer film can be further suppressed. １ is particularly preferably a group represented by the following formula (a) or formula (b): * in formula (a) and formula (b) represents a bond bonded to the aromatic ring shown in formula (3).

[0045] R in the above formula (3) ２ ~R ８ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. The organic group may contain an oxygen atom, a nitrogen atom, a sulfur atom, or the like, or may be a hydrocarbon group. ２, R ４ , R ５ , R ６ , R ７ , and R ８ are each independently preferably a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylamino group, an anilino group, an acylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, an alkylthio group, or an arylthio group, and are more preferably a hydrogen atom.

[0046] R in the above formula (3) ３ is a hydrogen atom or an organic group having 1 to 20 carbon atoms. The organic group may contain an oxygen atom, a nitrogen atom, a sulfur atom, or the like, or may be a hydrocarbon group. ３ From the viewpoint of further suppressing coloration of the interlayer film, R is preferably an organic group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 10 carbon atoms or an organic group having an ester structure having 1 to 10 carbon atoms. Furthermore, the hydrocarbon group having 1 to 10 carbon atoms preferably has either a quaternary carbon atom or an aromatic ring, or both. ３ is particularly preferably a group represented by the following formula (c), formula (d) or formula (e). * in formula (c), formula (d) and formula (e) represents a bond bonded to the aromatic ring shown in formula (3).

[0047] From the viewpoint of suppressing discoloration of the interlayer film of the present invention, among compounds having a benzotriazole structure of formula (3), any of the compounds of the following formulas (4) to (6) is preferred, and the compound of formula (4) or (5) is more preferred.

[0048] As the ultraviolet absorber having a benzotriazole structure, commercially available products can be used, and examples thereof include "Tinuvin 640," "Tinuvin 326," "Tinuvin 234," and "Tinuvin 328" manufactured by BASF, and RIASORB UV-326, UV-327, UV-328, UV-928, and UV-234 manufactured by Rianlon.

[0049] The content of the ultraviolet absorber per 100 parts by mass of the ionomer resin is not particularly limited, but is preferably 0.05 parts by mass or more and 0.5 parts by mass or less, and more preferably 0.1 parts by mass or more and 0.4 parts by mass or less. When the content of the ultraviolet absorber is at least these lower limits, yellowing of the interlayer film over time due to light and heat is more easily suppressed. When the content of the ultraviolet absorber is at most these upper limits, the effect corresponding to the added amount is easily obtained, use of more than the necessary amount can be suppressed, and the composition for forming the interlayer film can be easily kneaded.

[0050] <Silane Coupling Agent> The interlayer film may contain additives other than the above-mentioned ultraviolet absorbers, phenolic antioxidants, and N-C hindered amine light stabilizers. The interlayer film preferably contains, for example, a silane coupling agent as the additive. By including a silane coupling agent, the interlayer film is more likely to improve its adhesion to substrates, glass, and the like. Examples of silane coupling agents include those having a functional group such as a group containing a polymerizable carbon-carbon double bond, such as a vinyl group or a (meth)acryloyl group, an amino group, or an epoxy group, and a hydrolyzable group such as an alkoxy group.

[0051] Examples of silane coupling agents having a polymerizable carbon-carbon double bond include vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldiethoxysilane, and 3-acryloxypropyltriethoxysilane. Examples of silane coupling agents having an amino group include N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride. Examples of silane coupling agents having an epoxy group include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane. The interlayer film may contain one type of silane coupling agent alone or two or more types.

[0052] Among these, from the viewpoint of improving adhesion to glass and substrates, silane coupling agents having an amino group are preferred, and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane is particularly preferred. From the viewpoint of improving adhesion to glass and substrates, the content of the silane coupling agent in the interlayer film is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.005% by mass or more and 2% by mass or less, even more preferably 0.01% by mass or more and 1% by mass or less, and even more preferably 0.05% by mass or more and 0.5% by mass or less, based on 100% by mass of the entire interlayer film.

[0053] <Other Additives> The interlayer film of the present invention may contain additives other than the above-mentioned ultraviolet absorber, phenolic antioxidant, N-C hindered amine light stabilizer, and silane coupling agent. Examples of other additives include plasticizers, light stabilizers, antistatic agents, surfactants, colorants, foaming agents, lubricants, crystal nucleating agents, crystallization accelerators, crystallization retarders, catalyst deactivators, heat absorbers, heat reflectors, heat dissipation agents, inorganic fillers, organic fillers, impact 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, and dispersants.

[0054] <Melting Point of Additives> The interlayer film of the present invention contains the above-mentioned ultraviolet absorber, phenolic antioxidant, and N-C hindered amine light stabilizer as additives. The interlayer film of the present invention may also contain, as necessary, a silane coupling agent or other additives as additives. From the viewpoint of facilitating the kneading of the resin composition used to form the interlayer film, the melting point of the additive with the highest melting point contained in the interlayer film is preferably lower than 200°C, more preferably lower than 180°C, and even more preferably 180°C or lower. The melting point of the additive is the endothermic peak temperature of the melting curve measured using a DSC (differential scanning calorimeter). The DSC measurement is performed by increasing the temperature from room temperature (25°C) at a rate of 10°C / min.

[0055] <MFR of Interlayer Film> From the viewpoint of increasing the extrusion rate of the resin composition for forming the interlayer film and facilitating molding processability, the melt flow rate (MFR) of the interlayer film of the present invention is, for example, 0.01 g / 10 min or more and 150 g / 10 min or less, preferably 0.01 g / 10 min or more and 50 g / 10 min or less, more preferably 0.1 g / 10 min or more and 30 g / 10 min or less, even more preferably 0.1 g / 10 min or more and 10 g / 10 min or less, and still more preferably 1 g / 10 min or more and 5 g / 10 min or less. The MFR of the interlayer film is measured at 190°C and a load of 2.16 kg in accordance with JIS K7210-1 (2014).

[0056] <Haze> The interlayer film of the present invention preferably has high transparency, particularly when used in buildings. From this perspective, the haze value of a laminated glass made from two 2.0 mm thick clear glass sheets and the interlayer film of the present invention is preferably 2% or less, more preferably 1% or less, and even more preferably 0.5% or less. The haze value can be measured in accordance with JIS K 7105:1981.

[0057] <Thickness> The thickness of the interlayer film is not particularly limited, but is preferably 0.2 mm or more and 4 mm or less. By making the thickness of the interlayer film 0.2 mm or more, the mechanical strength, adhesiveness, and penetration resistance when the interlayer film is used in laminated glass can be improved. Furthermore, by making the thickness 4 mm or less, the transparency of the interlayer film can be easily ensured. The thickness of the interlayer film is more preferably 0.4 mm or more, and even more preferably 0.6 mm or more. Furthermore, it is more preferably 2.5 mm or less, even more preferably 1.6 mm or less, and even more preferably 1.0 mm or less.

[0058] <Width> The interlayer film of the present invention preferably has a width of 1 m or more. A width of 1 m or more makes the interlayer film suitable for use in large-sized laminated glass, laminated glass for architectural structures, and the like. The width of the interlayer film is more preferably 2 m or more. Furthermore, the interlayer film is not particularly limited, but from the viewpoint of improving productivity, it is preferably 5 m or less, more preferably 4 m or less.

[0059] The interlayer film of the present invention is preferably an extrusion molded product obtained by extrusion molding, as described below. By using an extrusion molded product, it becomes easy to industrially mass-produce large interlayer films having a width of 1 m or more, as described above.

[0060] <Resin Composition> The present invention can also provide a resin composition for forming the above-described interlayer film. The composition of the resin composition is the same as that of the above-described interlayer film. That is, the resin composition contains an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer. The resin composition may also contain additives such as a silane coupling agent, as needed. The contents of the ionomer resin, ultraviolet absorber, phenolic antioxidant, N-C hindered amine light stabilizer, and optionally the silane coupling agent, etc., in the resin composition are as described for the above-described interlayer film.

[0061] <Masterbatch> In the present invention, a masterbatch containing the above-described ionomer resin, UV absorber, phenolic antioxidant, and N-C hindered amine light stabilizer can also be provided. For example, the masterbatch and the ionomer resin can be mixed to obtain the above-described resin composition, and an interlayer film can be produced from the resin composition. When a masterbatch is used, the UV absorber, phenolic antioxidant, and N-C hindered amine light stabilizer can be easily mixed with the ionomer resin.

[0062] The masterbatch can be prepared by mixing an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer. The form of the masterbatch is not particularly limited, but it is typically in the form of pellets or other particles.

[0063] The content of each component in the masterbatch is not particularly limited, but is preferably as follows. The content of the ultraviolet absorber in the masterbatch is preferably 0.01 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the ionomer resin. The content of the phenolic antioxidant in the masterbatch is preferably 0.05 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the ionomer resin. The content of the N-C hindered amine light stabilizer in the masterbatch is preferably 0.01 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the ionomer resin.

[0064] <Structure of Interlayer Film> The interlayer film of the present invention is preferably composed of a single layer film. The layer constituting the monolayer film may be composed of the resin composition described above. That is, the layer constituting the monolayer film may be composed of a resin composition containing an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer, and the monolayer film may be formed from this resin composition. The interlayer film of the present invention may also be a multilayer film consisting of two or more layers. The multilayer film may have the overall composition described above for the interlayer film, but the resin composition constituting each layer may have the composition described above for the interlayer film. That is, each layer may be composed of a resin composition containing an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer, as described above for the interlayer film. In the multilayer film, the compositions of the layers may be different or the same.

[0065] <Method for Manufacturing Interlayer Film> The interlayer film may be prepared by preparing a resin composition for forming the interlayer film and molding the resin composition. The interlayer film may be prepared by mixing components constituting the interlayer film, such as an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, an N-C hindered amine light stabilizer, and additives as needed, to obtain a resin composition. The resulting resin composition may then be heated and melted as needed, and formed into a film by extrusion molding, press molding, roll molding, or the like to obtain a film. The method for mixing the components to obtain the resin composition is not particularly limited, but kneading using an extruder is preferred. As described above, a resin composition containing a masterbatch and an ionomer resin may also be used. Furthermore, when the interlayer film is multilayered, resin compositions for forming each layer may be prepared, and the resulting resin composition may be heated and melted as needed, and formed into a film by extrusion molding, press molding, roll molding, or the like to form each layer. The interlayer film may then be laminated to obtain a multilayered interlayer film. When the interlayer film is multilayered, co-extrusion may be used for the extrusion molding. Among the above methods, extrusion molding is preferred for forming the interlayer film. By using extrusion molding, wide interlayer films can be produced efficiently.

[0066] <Laminate> The present invention can provide a laminate including the above-described interlayer film. Specifically, the present invention can provide a laminate including an interlayer film and a pair of substrates, with the interlayer film disposed between the pair of substrates. In the laminate, the pair of substrates may be bonded via the interlayer film. Furthermore, in the laminate, the interlayer film disposed between the pair of substrates may be a single film, or multiple interlayer films may be disposed between the pair of substrates. By disposing multiple interlayer films between the pair of substrates, even when a large interlayer film thickness is required between a pair of glass members, such as in laminated glass for buildings, it is possible to use an interlayer film of a general thickness. Note that the multiple interlayer films may be integrated between the substrates, and the pair of substrates may be bonded via the integrated multiple interlayer films. The total thickness of the interlayer films between the substrates in the laminate is not particularly limited, but is, for example, 0.2 mm to 6 mm, preferably 0.4 mm to 4.5 mm, and more preferably 0.6 mm to 3.6 mm. Although another layer may be provided between the interlayer film and the substrate, it is preferable that no other layer is provided and the interlayer film is disposed so as to be in direct contact with the substrate. Furthermore, when multiple interlayer films are used, another layer may be provided between the multiple interlayer films, but it is preferable that no other layer is provided and the interlayer films are in direct contact with each other.

[0067] The substrates are a pair of substrates selected from the group consisting of organic material substrates and inorganic material substrates, and both of the substrates may be organic material substrates, both of the substrates may be inorganic material substrates, or one of the substrates may be an organic material substrate and the other an inorganic material substrate.

[0068] Examples of organic material substrates include organic resin plates and resin films. Organic resin plates are also called organic glass plates. Examples of organic resin plates include, but are not limited to, (meth)acrylic plates such as polycarbonate plates and polymethyl methacrylate plates, polyester plates such as acrylonitrile-styrene copolymer plates, acrylonitrile-butadiene-styrene copolymer plates, and polyethylene terephthalate plates, as well as various organic glass plates such as fluorine-based resin plates, polyvinyl chloride plates, chlorinated polyvinyl chloride plates, polypropylene plates, polystyrene plates, polysulfone plates, epoxy resin plates, phenolic resin plates, unsaturated polyester resin plates, and polyimide resin plates. The organic resin plates may be subjected to appropriate surface treatments. The thickness of the organic resin plate is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.4 mm or more, and preferably 5.0 mm or less, more preferably 3.0 mm or less.

[0069] The resin film is not particularly limited, but examples thereof include polyester resin films such as (meth)acrylic resin films, polycarbonate films, polyethylene terephthalate (PET) films, and polyethylene naphthalate (PEN) films; polyolefin resin films such as polyethylene films and polypropylene films; cyclic polyolefin (COP) films, triacetyl cellulose (TAC) films, polyethersulfone (PES) resin films, and polyimide resin films. The resin film may also be a polarizing film. A functional layer such as a hard coat layer made of a (meth)acrylic resin may be appropriately provided on the surface of the resin film, and electrodes, sensors, and the like may be attached. The thickness of the resin film is not particularly limited, but is preferably 30 μm or more, more preferably 50 μm or more, and preferably 500 μm or less, and more preferably 450 μm or less.

[0070] Among the above, the organic material substrate is preferably at least one selected from the group consisting of a polarizing film, a polyethylene terephthalate film, a polycarbonate plate, and a (meth)acrylic plate.

[0071] Examples of inorganic material substrates include inorganic glass plates. The inorganic glass plates are not particularly limited, but include various glass plates such as float glass, tempered glass, colored glass, polished glass, patterned glass, wired glass, lined glass, ultraviolet absorbing glass, infrared reflecting glass, infrared absorbing glass, and green glass. The inorganic glass may be subjected to surface treatment. The thickness of the inorganic glass is not particularly limited, but is preferably 0.1 mm or more, more preferably 1.0 mm or more, and is preferably 5.0 mm or less, more preferably 3.0 mm or less.

[0072] The laminate of the present invention can be used to produce laminated glass. The laminated glass includes a pair of substrates and an interlayer film disposed between the pair of substrates. The substrates can be glass members selected from the inorganic glass plates and organic glass plates described above. When the laminate is laminated glass, for example, one or more interlayer films are sandwiched between two glass members and passed through a pressure roll, or placed in a rubber bag and subjected to vacuum suction to remove any air remaining between the two glass members and the interlayer film. This is followed by pre-bonding at approximately 70 to 110°C to obtain a laminated intermediate. The laminated intermediate can then be placed in an autoclave or pressed at approximately 120 to 150°C and a pressure of 1 to 1.5 MPa for full bonding. In this manner, laminated glass can be obtained. When multiple interlayer films are disposed between a pair of glass members, the multiple interlayer films can be integrated by either pre-bonding or full bonding.

[0073] The interlayer film, laminate, and laminated glass of the present invention can be used in a variety of fields, including electronic devices such as displays, vehicles such as automobiles, railway cars, aircraft, and ships, and various buildings such as buildings, condominiums, detached houses, halls, and gymnasiums. Among these, their use in vehicles and buildings is preferred, and the interlayer film of the present invention and the laminate and laminated glass containing it are more preferred for buildings because they are less likely to yellow over time due to light and heat. Laminated glass is preferably used in vehicles and buildings. Furthermore, in vehicle applications, the glass may be used as window glass, and in automobiles, for example, it may be used as any of the windshield, rear glass, and side glass. In buildings, the glass may be used as window glass, glass floors, curtain walls, and the like. When used in buildings, the laminated glass may be made larger and used as structural glazing, for example.

[0074] The present invention will be explained in more detail by way of examples, but the present invention is not limited to these examples in any way.

[0075] The measurements and evaluations of various physical properties were carried out as follows.

[0076] [Thickness of Interlayer Film] The thickness of the interlayer film was measured as an average of 10 points using a microscope "DSX500" manufactured by Olympus Corporation.

[0077] [Content of each structural unit and degree of neutralization] The mass % of each structural unit of the ionomer resin was determined by the following hydrochloric acid treatment: １ H-NMR and IR measurements were carried out to determine the content. [Hydrochloric acid treatment] 500 μL of ethanol and 1 mL of hydrochloric acid were added to 100 mg of a sample that had been freeze-pulverized using a JFC-2000 (manufactured by Japan Analytical Industry Co., Ltd.), and the mixture was stirred at 60°C for 48 hours. The mixture was then washed three times with ultrapure water to remove the hydrochloric acid, and dried by heating.

[0078] [Degree of Neutralization] The degree of neutralization was determined by subjecting the sample before and after the hydrochloric acid treatment to IR measurement. －１ Based on the methylene peak height of 1700 cm －１The carboxylic acid peak height was calculated using the following formula: In the following formula, the denominator is the peak height of 1700 cm for the sample after the hydrochloric acid treatment. －１ Peak height / 1460 cm －１ The peak height of the molecule is 1700 cm for the sample before hydrochloric acid treatment. －１ Peak height: 1460cm －１ represents the peak height of

[0079] [ １ H-NMR Measurement] The sample after the hydrochloric acid treatment was dissolved in a solvent (tetrachloroethane:dimethyl sulfoxide = 5:2) to a concentration of about 1 to 3 mass % to prepare a measurement solution. １ H-NMR measurement (apparatus: AVANCE 400 (PRODIGY), spectrometer: AVANCE III HD) was carried out. The measurement conditions were an accumulation of 8 times and a temperature of 120°C. In the analysis, the integrated value of H derived from the methyl group of methacrylic acid was used as the reference, and this value was set to 3.00. At that time, the total mass% of the structural units (A) and (B) and the mass% content of the ethylene-derived structural unit (C) were calculated from the integrated intensity ratio of the H peak derived from methylene appearing at 1.15-1.62 ppm. Furthermore, the respective contents of the structural units (A) and (B) were calculated from the above-mentioned degree of neutralization.

[0080] <MFR of Interlayer Film> The MFR of the interlayer film of each example and comparative example was measured at 190°C under a load of 2.16 kg in accordance with JIS K7210-1 (2014).

[0081] <Haze of Interlayer Film> An interlayer film (5 cm long x 5 cm wide) from each Example and Comparative Example was sandwiched between two sheets of clear glass (5 cm long x 5 cm wide x 2.0 mm thick) conforming to JIS R3202 (2011) to obtain a laminate. This laminate was placed in a rubber bag and degassed at a vacuum of 2.6 kPa for 20 minutes, then transferred to an oven in the degassed state and held at 90°C for 30 minutes to perform vacuum pressing, thereby temporarily bonding the laminate. The temporarily bonded laminate was then pressure-bonded in an autoclave for 20 minutes under conditions of 135°C and a pressure of 1.2 MPa to obtain a laminated glass consisting of a glass plate / interlayer film / glass plate. The haze value of the laminated glass prepared as described above was measured using a HAZE METER "HM-150N" manufactured by Murakami Color Co., Ltd. in accordance with JIS K6714.

[0082] <Evaluation of Yellowness Change by Heat Resistance Test> Laminated glass was produced using the interlayer films of each Example and Comparative Example in the same manner as described above for measuring the haze of the interlayer film. The yellow index value (YI value) of the laminated glass was measured at 23°C. This was defined as the initial YI value. The laminated glass was then placed in an oven at 100°C, and after 3000 hours had passed, it was removed from the oven and, once the surface temperature of the laminated glass had reached 23°C, the yellow index value (YI value) was measured. This was defined as the YI value after the heat resistance test. ΔYI was calculated using the following formula and evaluated according to the following criteria. The YI value was measured as the YI value (yellowness, yellow index) of the obtained laminated glass by a transmission method in accordance with JIS K7105:1981 using a spectrophotometer ("U-4100" manufactured by Hitachi High-Technologies Corporation). ΔYI=YI value after heat resistance test−initial YI value (Evaluation criteria for change in yellowness due to heat resistance test) A: ΔYI in the heat resistance test is 2 or less B: ΔYI in the heat resistance test is more than 2

[0083] After the heat resistance test, the laminated glass was visually inspected for yellowing at the edge and evaluated as follows: (Evaluation of edge yellowing after heat resistance test) A: No edge yellowing B: Edge yellowing

[0084] <Evaluation of Yellowness Change by Light Irradiation Test> Laminated glass was produced using the interlayer films of each Example and Comparative Example using the same method as described above for measuring the haze of the interlayer film. The yellow index value (YI value) of the laminated glass was measured at 23°C. This was defined as the initial YI value. The laminated glass was then irradiated with light from a xenon (Xe) light source for 3,000 hours. The light irradiation test was performed using an SX-75 model manufactured by Suga Test Instruments Co., Ltd. The resulting laminated glass (the laminated glass before the light irradiation test) was fixed to a sample fixture so that one edge of the laminated glass was exposed. One of the surfaces of the fixed laminated glass was irradiated with xenon light at an irradiance of 60 W / m2 (irradiance measurement wavelength: 300 to 400 nm) for 3,000 hours at a black panel temperature of 63°C and a chamber humidity of 50% RH. (Inner filter: quartz, outer filter: #275) After irradiation was completed, the laminated glass was allowed to cool, and when the surface temperature reached 23°C, the yellow index value (YI value) was measured. This was taken as the YI value after light irradiation. ΔYI was calculated using the following formula and evaluated according to the following criteria: ΔYI = YI value after light irradiation - initial YI value (Evaluation criteria for yellowness change due to light irradiation test) A: ΔYI in the light irradiation test is 1.5 or less B: ΔYI in the light irradiation test is more than 1.5

[0085] <Overall evaluation: judgment> A: When the results of the evaluation of yellowness change in the heat resistance test, evaluation of edge yellowing after the heat resistance test, and evaluation of yellowness change in the light irradiation test are all A. B: When at least one of the evaluations of yellowness change in the heat resistance test, evaluation of edge yellowing after the heat resistance test, and evaluation of yellowness change in the light irradiation test is B.

[0086] <Regarding each component used in the examples and comparative examples> (Resins) Ionomer resin: an ionomer resin obtained by neutralizing an ethylene-methacrylic acid copolymer with magnesium ions, metal species Mg, degree of neutralization 66%, structural unit (A) 6.7% by mass, structural unit (B) 13.0% by mass, structural unit (C) 80.3% by mass. In Table 1, this is shown as "Ionomer Resin 1." Polyvinyl acetal resin: average degree of polymerization 3,300, hydroxyl group amount 30.8 mol%, acetylation degree 0.8 mol%, acetalization degree 68.4 mol%, shown as "PVB1" in Table 1.

[0087] (Antioxidants) Phenolic antioxidant: "IRGANOX 1010" manufactured by BASF, an antioxidant having four phenolic groups with t-butyl groups at both ortho positions, melting point 110 to 125°C. Phosphorus-based antioxidant: "ADEKA STAB 2112" manufactured by ADEKA, powder, melting point 180 to 190°C. Phosphorus-based antioxidant: "ADEKA STAB 3010" manufactured by ADEKA, liquid at room temperature (25°C).

[0088] (Ultraviolet absorber) Ultraviolet absorber: an ultraviolet absorber having a benzotriazole structure, "Tinuvin 640" manufactured by BASF, melting point 109 to 113°C, shown as "UV-640" in Table 1. Ultraviolet absorber: an ultraviolet absorber having a benzotriazole structure, "Tinuvin 326" manufactured by BASF, melting point 137 to 141°C, shown as "T-326" in Table 1.

[0089] (Light stabilizer) N-C type hindered amine light stabilizer: "Tinuvin 765" manufactured by BASF, a hindered amine light stabilizer having two structures represented by formula (1). In Table 1, it is shown as "HS765". It is a liquid at room temperature (25°C).

[0090] (Silane Coupling Agent) Silane coupling agent: "KBM-602", N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd. Liquid at room temperature (25° C.).

[0091] Example 1 100 parts by mass of ionomer resin 1, 0.3 parts by mass of antioxidant (IRGANOX1010), 0.2 parts by mass of ultraviolet absorber (UV-640), 0.1 parts by mass of N-C type hindered amine light stabilizer (HS765), and 0.15 parts by mass of silane coupling agent (KBM-602) were charged into an extruder, kneaded at 170°C, and extruded to obtain an interlayer film having a thickness of 0.76 mm and a width of 1 m. The various evaluations described above were carried out using this interlayer film.

[0092] [Examples 2 to 4, Comparative Examples 1 to 12] Interlayer films were obtained in the same manner as in Example 1, except that the types and amounts of each component were changed as shown in Table 1. The interlayer films were used to carry out the various evaluations described above.

[0093]

[0094] The interlayer films shown in each example contained an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer. The laminated glass produced using these interlayer films was able to suppress yellowing over time due to light and heat. In contrast, Comparative Examples 1 to 11 were examples of interlayer films containing an ionomer resin but not containing at least one of an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer. These interlayer films were unable to suppress yellowing over time due to light and heat. Comparative Example 12 was an example in which an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer were used in combination, but a polyvinyl acetal resin was used as the resin instead of an ionomer resin. Comparative Example 12 resulted in edge yellowing during a heat resistance test. From the above, it can be seen that the combined use of an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer in an interlayer film containing an ionomer resin is effective from the perspective of suppressing yellowing over time due to light and heat.

Claims

1. An interlayer film comprising an ionomer resin, an ultraviolet absorber, a phenolic antioxidant, and an N-C hindered amine light stabilizer.

2. The interlayer film according to claim 1, wherein the phenolic antioxidant has a structure including a phenol group having a t-butyl group at at least one ortho position.

3. The interlayer film according to claim 1 or 2, wherein the N-C hindered amine light stabilizer has a structure represented by formula (1). (In formula (1), *1 and *2 each represent a bond, and *1 represents a bond bonded to a carbon atom.) 4. The interlayer film according to claim 1 or 2, wherein the content of the phenolic antioxidant is 0.05 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of the ionomer resin.

5. The interlayer film according to claim 1 or 2, wherein the content of the N-C type hindered amine light stabilizer relative to 100 parts by mass of the ionomer resin is 0.01 parts by mass or more and 0.5 parts by mass or less.

6. The interlayer film according to claim 1 or 2, wherein the content of the antioxidant other than the phenol-based antioxidant is 0.3 parts by mass or less per 100 parts by mass of the ionomer resin.

7. The interlayer film according to claim 1 or 2, wherein the content of the hindered amine light stabilizer other than the N-C hindered amine light stabilizer is 0.3 parts by mass or less relative to 100 parts by mass of the ionomer resin.

8. The interlayer film according to claim 1 or 2, wherein the additive having the highest melting point among the additives contained in the interlayer film has a melting point lower than 180°C.

9. The interlayer film according to claim 1 or 2, wherein the ultraviolet absorber is a compound having a benzotriazole structure.

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

11. The interlayer film according to claim 1 or 2, wherein the ionomer resin comprises a structural unit (A) derived from (meth)acrylic acid, a structural unit (B) derived from a neutralized product of (meth)acrylic acid, and a structural unit (C) derived from ethylene.

12. The interlayer film according to claim 11, wherein the ionomer resin has a total content of the structural units (A) and (B) of 10% by mass or more and 25% by mass or less, based on the total amount of the structural units constituting the ionomer resin.

13. The interlayer film according to claim 11, wherein the ionomer resin has a content of the structural unit (B) of 4 mass% or more and 17.5 mass% or less, based on the total amount of structural units constituting the ionomer resin.

14. The interlayer film according to claim 11, wherein the structural unit (B) in the ionomer resin contains sodium, zinc, or magnesium.

15. The interlayer film according to claim 1 or 2, wherein the haze value of a laminated glass made from two 2.0 mm thick clear glass sheets and the interlayer film is 2% or less.

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

17. Laminated glass comprising the laminate of claim 16.

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