WO2023190191A1

WO2023190191A1 - Epoxy resin composition, sealing material, and image display device

Info

Publication number: WO2023190191A1
Application number: PCT/JP2023/011893
Authority: WO
Inventors: 薫須田; 宙宮尾
Original assignee: 三井化学株式会社
Priority date: 2022-03-30
Filing date: 2023-03-24
Publication date: 2023-10-05
Also published as: TW202344594A

Abstract

This epoxy resin composition comprises an epoxy resin, a styrene-based viscosity adjuster, polyisobutylene and a compatibilizer. The compatibilizer has a diblock structure containing a styrene-derived structure and an olefin-derived structure. The mixing ratio of the compatibilizer is 30-120 parts by mass with respect to 100 parts by mass of the polyisobutylene. The mixing ratio of the compatibilizer is 80-350 parts by mass with respect to 100 parts by mass of the styrene-based viscosity adjuster.

Description

Epoxy resin compositions, encapsulants and image display devices

The present invention relates to an epoxy resin composition, a sealing material, and an image display device.

In recent years, organic EL displays, for example, have been known as image display devices equipped with optical elements. In such an image display device, the optical element is sealed with a sealant in order to prevent the optical element from deteriorating due to moisture in the atmosphere.

As a sealing composition for forming such a sealing material, for example, a thermosetting resin composition containing a thermosetting resin (epoxy resin) has been proposed (see, for example, Patent Document 1). .

International Publication 2021/117597 pamphlet

On the other hand, sealing materials are required to have even lower moisture permeability.

In order to improve the low moisture permeability, blending polyisobrene with low moisture permeability into the resin is considered, but especially when the resin is an epoxy resin, the compatibility between the epoxy resin and polyisobutylene is low. Therefore, there is a problem that a uniform liquid mixture cannot be obtained.

The present invention provides an epoxy resin composition with excellent compatibility and low moisture permeability, a sealant containing a cured product of the epoxy resin composition, and an image display device equipped with the sealant.

The present invention [1] includes an epoxy resin, a styrene-based viscosity modifier, polyisobutylene, and a compatibilizer, and the compatibilizer has a diblock structure containing a styrene-derived structure and an olefin-derived structure. The blending ratio of the compatibilizer is 30 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of polyisobutylene, and the blending ratio of the compatibilizer is 100 parts by mass of a styrene-based viscosity modifier. The amount of the epoxy resin composition is 80 parts by mass or more and 350 parts by mass or less.

The present invention [2] includes a sealing material containing a cured product of the epoxy resin composition described in the above [1].

The present invention [3] includes an image display device including an optical element and the sealing material according to the above [2] that seals the optical element.

The epoxy resin composition of the present invention contains polyisobutylene. Therefore, it has excellent low moisture permeability.

This epoxy resin composition also contains a compatibilizer (a compatibilizer having a diblock structure containing a styrene-derived structure and an olefin-derived structure) in a predetermined ratio for each of the polyisobutylene and the styrene-based viscosity modifier. agent). Therefore, it has excellent compatibility.

The sealing material of the present invention includes a cured product of the epoxy resin composition of the present invention. Therefore, it has excellent compatibility.

The image display device of the present invention includes an optical element and the sealing material of the present invention that seals the optical element. Therefore, it has excellent low moisture permeability.

The epoxy resin composition includes an epoxy resin, a styrene-based viscosity modifier, polyisobutylene, and a compatibilizer.

<Epoxy resin>
Examples of epoxy resins include aliphatic epoxy resins, alicyclic epoxy resins, and aromatic epoxy resins.

[Aliphatic epoxy resin]
An aliphatic epoxy resin is a curable resin that has an epoxy group and no aliphatic ring (alicyclic skeleton) or aromatic ring.

Examples of aliphatic epoxy resins include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and , 1,6-hexanediol diglycidyl ether.

[Alicyclic epoxy resin]
Alicyclic epoxy resin is a curable resin that has an epoxy group and an aliphatic ring (alicyclic skeleton) and does not have an aromatic ring.

Examples of alicyclic epoxy resins include glycidyl group-containing alicyclic epoxy resins, glycidyl ether group-containing alicyclic epoxy resins, and epoxycyclo structure-containing epoxy resins.

(Glycidyl group-containing alicyclic epoxy resin)
A glycidyl group-containing alicyclic epoxy resin has, for example, a glycidyl group bonded to an aliphatic ring. Such a glycidyl group-containing alicyclic epoxy resin is represented by the following general formula (1), for example.

In the above formula (1), R1 represents a monovalent organic group, and n represents the degree of polymerization. Further, a substituent such as an alkyl group may be bonded to the carbon atom constituting the cyclohexane ring.

Specifically, the glycidyl group-containing alicyclic epoxy resin represented by the above general formula (1) includes 1,2-epoxy-4-(2-oxiranyl) of 2,2-bis(hydroxymethyl)-1-butanol. ) cyclohexane adducts.

A commercially available product can also be used as the glycidyl group-containing alicyclic epoxy resin represented by the above general formula (1). As a commercially available glycidyl group-containing alicyclic epoxy resin represented by the above general formula (1), for example, EHPE3150 (epoxy equivalent: 170 to 190 g/eq., manufactured by Daicel Corporation) can be mentioned.

(Glycidyl ether group-containing alicyclic epoxy resin)
A glycidyl ether group-containing alicyclic epoxy resin has a glycidyl ether unit bonded to an aliphatic ring. Preferably, the glycidyl ether group-containing cycloaliphatic epoxy resin is a polyglycidyl ether-containing cycloaliphatic epoxy resin having a plurality of glycidyl ether units bonded to an aliphatic ring.

Examples of the glycidyl ether-containing alicyclic epoxy resin include bifunctional glycidyl ether-containing alicyclic epoxy resins. Examples of the bifunctional glycidyl ether-containing alicyclic epoxy resin include hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, and hexahydrophthalic acid diglycidyl ester.

(Epoxy resin containing epoxy cyclo structure)
An epoxy cyclo structure-containing epoxy resin has an epoxy cyclo structure that has an epoxy group composed of two adjacent carbon atoms forming an aliphatic ring and one oxygen atom bonded to those two carbon atoms. .

Examples of epoxy cyclo structure-containing epoxy resins include epoxy cyclohexane structure-containing epoxy resins (hereinafter referred to as ECH structure-containing epoxy resins).

ECH structure-containing epoxy resins include, for example, epoxy resins containing one ECH structure shown in the following chemical formula (2), epoxy resins containing one ECH structure shown in the following chemical formula (3), and the following general formula (4). ) and modified products thereof.

In the above formula (4), X represents a linking group (a divalent group having one or more atoms). R2 represents one atom or substituent selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, an aryl group, a furyl group, and a thienyl group. The two R2's in formula (4) may be the same or different.

The epoxy resin containing the two ECH structures shown in the above general formula (4) (hereinafter referred to as the ECH structure-containing epoxy resin shown in the general formula (4)) has an ECH structure (epoxycyclohexyl group) in the molecule. It has two epoxycyclohexyl groups at both ends and is bonded via a linking group. Note that the epoxycyclohexyl group is a functional group that includes a cyclohexane ring, an epoxy group composed of two adjacent carbon atoms forming the cyclohexane ring, and one oxygen atom bonded to these two carbon atoms. It is.

Examples of the alkyl group represented by R2 in the above general formula (4) include linear or branched alkyl groups having 1 to 6 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, etc.).

Examples of the fluoroalkyl group represented by R2 in the above general formula (4) include linear or branched fluoroalkyl groups having 1 to 6 carbon atoms (e.g., perfluoromethyl group, perfluoroethyl group, perfluoropropyl group). etc.).

Examples of the aryl group represented by R2 in the above general formula (4) include aryl groups having 6 to 18 carbon atoms (eg, phenyl group, naphthyl group, etc.).

Examples of the linking group represented by X in the above general formula (4) include oxygen atom, sulfur atom, divalent hydrocarbon group, polyoxyalkylene group, carbonyl group, ether group, thioether group, ester group, carbonate group, Examples include an amide group and a group in which these are linked.

Examples of divalent hydrocarbon groups include linear or branched alkylene groups having 1 to 20 carbon atoms (e.g., methylene group, methylmethylene group, dimethylmethylene group, ethylene group, propylene group, trimethylene group, butylene group). ), linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms (eg, propenylene group, methylpropenylene group, butenylene group, etc.).

Examples of the polyoxyalkylene group include linear or branched polyoxyalkylene groups having 1 to 120 carbon atoms (eg, polyoxyethylene group, polyoxypropylene group, etc.).

Specifically, the ECH structure-containing epoxy resin represented by general formula (4) includes bis(3,4-epoxycyclohexylmethyl)ether, 1,2-bis(3,4-epoxycyclohexan-1-yl)ethane, , 2,2-bis(3,4-epoxycyclohexan-1-yl)propane, 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate, and ε-caprolactone modified 3',4'- Examples include epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and preferably 3,4-epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate.

Moreover, a commercially available product can also be used as the ECH structure-containing epoxy resin represented by the above general formula (4). Examples of commercially available epoxy resins containing the ECH structure represented by the above general formula (4) include Celloxide 8010, Celloxide 2021P (epoxy equivalent: 128 to 145 g/eq.), and Celloxide 2081 (manufactured by Daicel Corporation). .

Preferably, the alicyclic epoxy resin includes an epoxy cyclo structure-containing epoxy resin. More preferred examples of the alicyclic epoxy resin include ECH structure-containing epoxy resins represented by the above general formula (4).

The weight average molecular weight of the alicyclic epoxy resin is, for example, 200 or more, for example, 1000 or less, and preferably 500 or less. The weight average molecular weight (Mw) can be determined by gel permeation chromatography (GPC) using polystyrene as a standard substance (the same applies hereinafter).

Furthermore, the epoxy equivalent in the alicyclic epoxy resin is, for example, 90 g/eq. Above, preferably 100g/eq. Above, for example, 250g/eq. Below, preferably 190g/eq. It is as follows. The epoxy equivalent can be measured in accordance with JIS K7236:2001 (the same applies hereinafter).

[Aromatic epoxy resin]
Aromatic epoxy resin is a curable resin that has an epoxy group and an aromatic ring, but does not have an aliphatic ring (alicyclic skeleton).

Examples of aromatic epoxy resins include bisphenol type epoxy resins, diphenyl ether type epoxy resins, novolac type epoxy resins (e.g., phenol novolak type, cresol novolak type, biphenyl novolac type, bisphenol novolac type, naphthol novolak type, trisphenol novolak type) type, dicyclopentadiene novolac type), biphenyl type epoxy resin, and naphthalene type epoxy resin. Preferable aromatic epoxy resins include bisphenol-type epoxy resins and biphenyl-type epoxy resins.

Examples of bisphenol epoxy resins include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol E epoxy resin, bisphenol S epoxy resin, and bisphenol AD epoxy resin. Preferably, the bisphenol epoxy resin includes a bisphenol F epoxy resin.

Further, the aromatic epoxy resin may be solid at room temperature or liquid at room temperature. The aromatic epoxy resin is preferably solid at room temperature. Note that "solid at room temperature" refers to a solid state that does not have fluidity at room temperature (23°C), and "liquid at room temperature" refers to a liquid state that has fluidity at room temperature (23°C). .

The weight average molecular weight (Mw) of the aromatic epoxy resin is, for example, 1,000 or more, preferably 3,000 or more, and, for example, 10,000 or less, preferably 8,000 or less.

Furthermore, the epoxy equivalent in the aromatic epoxy resin is, for example, 1000 g/eq. Above, preferably 5000g/eq. Above, more preferably 8000g/eq. Above, for example, 12000g/eq. It is as follows.

From the viewpoint of improving low moisture permeability, preferable examples of the epoxy resin include alicyclic epoxy resins and aromatic epoxy resins.

Epoxy resins can be used alone or in combination of two or more. Preferably, an alicyclic epoxy resin and an aromatic epoxy resin are used together as the epoxy resin.

When an alicyclic epoxy resin and an aromatic epoxy resin are used together, the blending ratio of the alicyclic epoxy resin should be one with low moisture permeability based on 100 parts by mass of the total amount of the alicyclic epoxy resin and the aromatic epoxy resin. From the viewpoint of improving low moisture permeability, for example, 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and from the viewpoint of improving low moisture permeability, for example, 60 parts by mass or less, preferably, It is 48 parts by mass or less. In addition, the blending ratio of the aromatic epoxy resin is, for example, 40 parts by mass or more, preferably 52 parts by mass, from the viewpoint of improving low moisture permeability, with respect to 100 parts by mass of the total amount of the alicyclic epoxy resin and the aromatic epoxy resin. From the viewpoint of improving low moisture permeability, the amount is, for example, 80 parts by mass or less, preferably 70 parts by mass or less, and more preferably 65 parts by mass or less.

The blending ratio of the epoxy resin is, for example, 30 parts by mass or more, preferably 30 parts by mass or more, based on the total amount of the epoxy resin, styrene viscosity modifier, polyisobutylene, and compatibilizer, from the viewpoint of improving low moisture permeability. , 40 parts by mass or more, and, from the viewpoint of improving low moisture permeability, for example, 70 parts by mass or less, preferably 63 parts by mass or less, more preferably 58 parts by mass or less.

<Styrenic viscosity modifier>
The styrenic viscosity modifier is a component that imparts adhesive strength to the epoxy resin composition.

Examples of styrenic viscosity modifiers include styrene polymers, α-methylstyrene polymers, and styrene-α-styrene copolymers.

A commercially available styrene-based viscosity modifier can also be used. Commercially available styrene-based viscosity modifiers include, for example, the FTR series (eg, FTR-8120, FTR-8100, manufactured by Mitsui Chemicals, Inc.).

The weight average molecular weight (Mw) of the styrene-based viscosity modifier is, for example, 1000 or more, preferably 1200 or more, more preferably 1300 or more, from the viewpoint of improving low moisture permeability. , for example, 2000 or less, preferably 1500 or less.

The styrenic viscosity modifiers can be used alone or in combination of two or more.

The blending ratio of the styrene-based viscosity modifier is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, from the viewpoint of improving low moisture permeability, with respect to 100 parts by mass of the epoxy resin. From this point of view, the amount is, for example, 20 parts by mass or less, preferably 15 parts by mass or less.

In addition, the blending ratio of the styrene-based viscosity modifier is, for example, 1.0% with respect to 100 parts by mass of the total amount of the epoxy resin, styrene-based viscosity modifier, polyisobutylene, and compatibilizer from the viewpoint of improving low moisture permeability. The content is 0 parts by mass or more, preferably 5.0 parts by mass, and, from the viewpoint of improving low moisture permeability, for example, 10 parts by mass or less, preferably 7.8 parts by mass or less.

<Polyisobutylene>
Polyisobutylene is a component that imparts low moisture permeability to the epoxy resin composition.

The weight average molecular weight of polyisobutylene is, for example, 10,000 or more, preferably 30,000 or more, more preferably 45,000 or more, from the viewpoint of improving low moisture permeability, and, for example, 100,000 or less from the viewpoint of improving low moisture permeability. , preferably 70,000 or less, more preferably 50,000 or less.

From the viewpoint of improving low moisture permeability, the blending ratio of polyisobutylene is, for example, 15 parts by mass or more, preferably 25 parts by mass or more, more preferably 35 parts by mass or more, based on 100 parts by mass of the epoxy resin. , from the viewpoint of improving low moisture permeability, for example, 50 parts by mass or less.

In addition, the blending ratio of polyisobutylene is, for example, 100 parts by mass or more, preferably 120 parts by mass or more, more preferably 200 parts by mass or more, from the viewpoint of improving low moisture permeability, with respect to 100 parts by mass of the styrene-based viscosity modifier. The content is at least 250 parts by mass, more preferably at least 250 parts by mass, and from the viewpoint of improving low moisture permeability, for example, at most 600 parts by mass, preferably at most 450 parts by mass, more preferably at most 350 parts by mass.

In addition, from the viewpoint of improving low moisture permeability, the blending ratio of polyisobutylene is, for example, 10 parts by mass or more with respect to 100 parts by mass of the total amount of the epoxy resin, styrene-based viscosity modifier, polyisobutylene, and compatibilizer. Preferably, the amount is 15 parts by mass or more, and from the viewpoint of improving low moisture permeability, it is, for example, 40 parts by mass or less, preferably 30 parts by mass or less, and more preferably 25 parts by mass or less.

<Compatibilizer>
The compatibilizer is a component for improving compatibility (specifically, compatibility between the styrene viscosity modifier (epoxy resin) and polyisobutylene).

The compatibilizer has a diblock structure including a styrene-derived structure and an olefin-derived structure. If the compatibilizer has a diblock structure containing a styrene-derived structure and an olefin-derived structure, the compatibility between the styrene-based viscosity modifier (epoxy resin) and polyisobutylene can be improved.

An example of such a compatibilizer is a hydrogenated styrene-isoprene diblock copolymer represented by the following formula (5).

In the above formula (5), l and m indicate the degree of polymerization.

In the compatibilizer, the proportion of units having a styrene-derived structure is, for example, 30 mol% or more, preferably 40 mol%, based on the total amount of units having a styrene-derived structure and units having an olefin-derived structure. For example, it is 70 mol% or less, preferably 60 mol% or less. Further, the proportion of units having an olefin-derived structure is, for example, 30 mol% or more, preferably 40 mol% or more, with respect to the total amount of units having a styrene-derived structure and olefin-derived structures, and , for example, 70 mol% or less, preferably 60 mol% or less.

More preferably, in the compatibilizer, the proportion of units having a styrene-derived structure and the proportion of units having an olefin-derived structure are the same. In other words, the proportion of units having a styrene-derived structure is 50 mol% with respect to the total amount of units having a styrene-derived structure and units having an olefin-derived structure. The proportion is 50 mol%. Note that the proportion of units having a structure derived from styrene in the compatibilizer is preferably 0.5 or more and 10 or less with respect to the molecular chain of the styrene-based viscosity modifier.

A commercially available product can also be used as the compatibilizer. Examples of commercially available compatibilizers include Septon 1020 (manufactured by Kuraray Co., Ltd.).

The compatibilizers can be used alone or in combination of two or more.

The compounding ratio of the compatibilizer is 30 parts by mass or more, preferably 40 parts by mass or more, and 120 parts by mass or less, preferably 90 parts by mass or less, more preferably 70 parts by mass or less, based on 100 parts by mass of polyisobutylene. Parts by mass or less.

If the blending ratio of the compatibilizer to 100 parts by mass of polyisobutylene is equal to or higher than the above lower limit, compatibility (specifically, compatibility between the styrene viscosity modifier (epoxy resin) and polyisobutylene) and low moisture permeability are achieved. can be improved.

On the other hand, if the blending ratio of the compatibilizer to 100 parts by mass of polyisobutylene is less than the above-mentioned lower limit, the above-mentioned compatibility and low moisture permeability will decrease.

Furthermore, if the blending ratio of the compatibilizer to 100 parts by mass of polyisobutylene is below the above upper limit, low moisture permeability can be improved.

On the other hand, if the blending ratio of the compatibilizer to 100 parts by mass of polyisobutylene exceeds the above upper limit, the low moisture permeability will decrease.

Further, the blending ratio of the compatibilizer is 80 parts by mass or more, preferably 120 parts by mass or more, and 350 parts by mass or less, preferably 250 parts by mass or less, with respect to 100 parts by mass of the styrene-based viscosity modifier. More preferably, it is 200 parts by mass or less.

If the blending ratio of the compatibilizer to 100 parts by mass of the styrene-based viscosity modifier is at least the above lower limit, low moisture permeability can be improved.

On the other hand, if the blending ratio of the compatibilizer to 100 parts by mass of the styrene-based viscosity modifier is less than the above-mentioned lower limit, the low moisture permeability will decrease.

In addition, if the blending ratio of the compatibilizer to 100 parts by mass of the styrene-based viscosity modifier is below the above upper limit, the compatibility (specifically, the compatibility between the styrene-based viscosity modifier (epoxy resin) and polyisobutylene) ) and can improve low moisture permeability.

On the other hand, if the blending ratio of the compatibilizer to 100 parts by mass of the styrene-based viscosity modifier exceeds the above upper limit, the above compatibility and low moisture permeability will decrease.

Further, the blending ratio of the compatibilizer is, for example, 5 parts by mass or more, preferably 8 parts by mass or more, with respect to 100 parts by mass of the total amount of the epoxy resin, styrene-based viscosity modifier, polyisobutylene, and compatibilizer. Further, for example, the amount is 25 parts by mass or less, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less.

<Additives>
The epoxy resin composition can contain additives in appropriate proportions, if necessary.

Additives include, for example, polymerization initiators, other viscosity modifiers, leveling agents, silane coupling agents, fillers, sensitizers, antioxidants, antiaging agents, plasticizers, ultraviolet absorbers, preservatives, and , antibacterial agents.

The additives can be used alone or in combination of two or more.

[Polymerization initiator]
Examples of the polymerization initiator include thermal cationic polymerization initiators and photocationic polymerization initiators. Preferably, the polymerization initiator is a thermal cationic polymerization initiator.

A thermal cationic polymerization initiator is a thermal acid generator that generates an acid (cation) when heated.

As the thermal cationic polymerization initiator, a known thermal cationic polymerization initiator can be used. Examples of thermal cationic polymerization initiators include sulfonium salts having counteranions such as AsF ^6- , SbF ^6- , PF ^6- , BF ^4- , B(C ₆ F ₅ ) ₄ ^- , CF ₃ SO ₃ ^- , etc. Examples include phosphonium salts, quaternary ammonium salts, diazonium salts, and iodonium salts.

The polymerization initiators can be used alone or in combination of two or more types.

The blending ratio of the polymerization initiator is, for example, 1 part by mass or more, preferably 2 parts by mass or more, and, for example, 5 parts by mass or less, based on 100 parts by mass of the epoxy resin.

The blending ratio of the polymerization initiator is, for example, 0.1 part by mass or more, preferably 0.5 parts by mass, based on 100 parts by mass of the total amount of the epoxy resin, styrene viscosity modifier, polyisobutylene, and compatibilizer. The amount is not less than 5.0 parts by mass, preferably not more than 2.0 parts by mass.

[Other viscosity modifiers]
Other viscosity modifiers are viscosity modifiers other than the above-mentioned styrene-based viscosity modifiers. Specifically, other viscosity modifiers include, for example, petroleum resins, terpene resins, phenol resins, and rosin resins. Other viscosity modifiers preferably include petroleum resins.

Commercially available products can also be used as other viscosity modifiers. Other commercially available viscosity modifiers include, for example, QTN-1500 (petroleum resin, manufactured by Nippon Zeon Co., Ltd.).

Other viscosity modifiers can be used alone or in combination of two or more.

The blending ratio of other viscosity modifiers is, for example, 10 parts by mass or more, preferably 15 parts by mass or more, with respect to 100 parts by mass of the total amount of the epoxy resin, styrene viscosity modifier, polyisobutylene, and compatibilizer. Further, it is, for example, 30 parts by mass or less, preferably 20 parts by mass or less.

[Leveling agent]
The leveling agent is a component for improving the flatness of the sealing material obtained using the epoxy resin composition.

Examples of the leveling agent include silicone leveling agents, acrylic leveling agents, and fluorine leveling agents. Preferably, the leveling agent is a silicone leveling agent.

The leveling agents can be used alone or in combination of two or more.

The blending ratio of the leveling agent is, for example, 0.1 part by mass or more, or, for example, 1.0 part by mass with respect to 100 parts by mass of the total amount of the epoxy resin, styrene-based viscosity modifier, polyisobutylene, and compatibilizer. The amount is preferably 0.5 parts by mass or less.

[Silane coupling agent]
Examples of the silane coupling agent include a silane compound having an epoxy group, a silane compound having a carboxyl group, a silane compound having a methacryloyl group, a silane compound having an acid anhydride group, and a silane compound having an isocyanate group. Preferable examples of the silane coupling agent include silane compounds having an epoxy group.

The silane coupling agents can be used alone or in combination of two or more.

The blending ratio of the silane coupling agent is, for example, 0.1 part by mass or more, preferably 0.5 part by mass, based on 100 parts by mass of the epoxy resin, styrene viscosity modifier, polyisobutylene, and compatibilizer. parts or more, and for example, 3.0 parts by mass or less, preferably 1.0 parts by mass or less.

[Filling material]
Examples of fillers include silica, alumina, oxides (eg, titanium oxide, magnesium oxide), and hydroxides (eg, aluminum hydroxide, magnesium hydroxide). Preferably, the filler includes silica.

The fillers can be used alone or in combination of two or more.

The blending ratio of the filler is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, based on 100 parts by mass of the total amount of the epoxy resin, styrene viscosity modifier, polyisobutylene, and compatibilizer. It is 50 parts by mass or less, preferably 30 parts by mass or less.

<Preparation of epoxy resin composition>
To prepare an epoxy resin composition, an epoxy resin, a styrene-based viscosity modifier, polyisobutylene, a compatibilizer, and optional additives are mixed. In particular, when blending a polymerization initiator, the polymerization initiator is blended after components other than the polymerization initiator are blended. In this way, an epoxy resin composition is prepared.

Additionally, the epoxy resin composition can be diluted with a known organic solvent. That is, the epoxy resin composition can be prepared as an epoxy resin composition varnish.

When diluting the epoxy resin composition with a known organic solvent (for example, methyl ethyl ketone and toluene), the solid content concentration of the varnish of the epoxy resin composition is, for example, 10% by mass or more, or, for example, 50% by mass. It is as follows.

Such an epoxy resin composition has excellent compatibility (specifically, compatibility between the styrene viscosity modifier (epoxy resin) and polyisobutylene) and low moisture permeability. Therefore, it can be suitably used as a sealing material for sealing an optical element.

Specifically, the sealing material includes a cured product of the above-mentioned epoxy resin composition.

When the epoxy resin composition contains a thermal cationic polymerization initiator, the epoxy resin composition is cured by heating the epoxy resin composition.

As for the heating conditions, the curing temperature is, for example, 60°C or higher and, for example, 100°C or lower. The heating time is, for example, 1 minute or more and, for example, 60 minutes or less.

The cured product of the epoxy resin composition preferably has transparency. Specifically, the total light transmittance (according to JIS K 7361-1) of the cured product of the epoxy resin composition is, for example, 80% or more, preferably 85% or more, more preferably 90% or more, or , for example, 100% or less.

Since the sealing material contains the cured product of the above-mentioned epoxy resin composition, it has excellent low moisture permeability.

<Image display device>
The image display device includes an optical element and the sealing material that seals the optical element. Since the image display device includes the above sealing material, it has excellent low moisture permeability.

<Effect>
The epoxy resin composition includes polyisobutylene. Therefore, it has excellent low moisture permeability.

Specifically, the compatibilizer has a structure similar to a styrenic viscosity modifier and a structure similar to polyisobutylene. Specifically, the compatibilizer has both a styrene-derived structure similar to a styrene-based viscosity modifier and an olefin-derived structure similar to polyisobutylene.

Furthermore, the compatibilizer has a diblock structure in which the styrene-derived structure and the olefin-derived structure are combined.

Therefore, the compatibility between the styrene-based viscosity modifier and the epoxy resin that is highly compatible with the styrene-based viscosity modifier and polyisobutylene is improved.

On the other hand, if the compatibilizer contains a styrene-derived structure and an olefin-derived structure, but they do not have a diblock structure, for example, a block combination consisting of a styrene-derived structure - an olefin-derived structure - a styrene-derived structure In the case of a polymer, the distance between the styrene-derived structures at both ends is limited by chemical bonds, so compatibility will not improve unless the styrene-based viscosity modifier is adjacent to both ends.

On the other hand, since the compatibilizer in this epoxy resin composition has a structure derived from styrene at one end and a structure derived from olefin at the other end, the compatibility can be reliably improved.

Next, the present invention will be explained based on Examples and Comparative Examples, but the present invention is not limited by the Examples below. Note that "parts" and "%" are based on mass unless otherwise specified. In addition, the specific numerical values of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description are the corresponding blending ratios ( Substitute with the upper limit value (value defined as "less than" or "less than") or lower limit value (value defined as "more than" or "exceeding") of the relevant description, such as content percentage), physical property value, parameter, etc. be able to.

<Ingredient details>
The trade names and abbreviations of the components used in each Example and each Comparative Example will be explained in detail. CEL2021P: 3,4-epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate, ECH structure-containing epoxy resin shown in the above general formula (4), trade name "Celoxide 2021P", molecular weight: 252.3, epoxy equivalent :128-145g/eq. , Daicel Corporation jER-4005P: bisphenol F type epoxy resin solid at room temperature, weight average molecular weight 7582, epoxy equivalent 10000 g/eq. , product name "jER4005P", manufactured by Mitsubishi Chemical Corporation,
XY-6954B35: biphenyl type epoxy resin solid at room temperature, weight average molecular weight 36,691, epoxy equivalent 10000 g/eq. , product name "XY-6954B35", manufactured by Mitsubishi Chemical Corporation,
FTR-8120: Styrene viscosity modifier, weight average molecular weight 1420, Mitsui Chemicals FTR-8100: Styrene viscosity modifier, weight average molecular weight 1420, Mitsui Chemicals TETRAX-3T: Polyisobutylene, product name "Tetrax" Grade 3T", weight average molecular weight 49,000, ENEOS Corporation TETRAX-6T: polyisobutylene, trade name "Tetrax Grade 6T", weight average molecular weight 80,000, ENEOS Corporation Septon-1020: compatibilizer, hydrogenation Styrene-isoprene diblock copolymer (proportion of units with a styrene-derived structure: 50%, proportion of units with an olefin-derived structure: 50%), Tuftec M1943 manufactured by Kuraray Co., Ltd.: Compatibilizer, polystyrene-polybutadiene -Polystyrene block copolymer, Asahi Kasei Co., Ltd. CXC-1733: Thermal cationic polymerization initiator, Kusumoto Kasei Co., Ltd. QTN-1500: Other viscosity modifiers, petroleum resin, Nippon Zeon Co., Ltd. BYK-302: Silicone leveling agent , KBM-403 manufactured by Bick Chemie: 3-glycidoxypropyltriethoxysilane, X12-967C manufactured by Shin-Etsu Chemical Co., Ltd.: Silane coupling agent with acid anhydride, KBM-4803 manufactured by Shin-Etsu Chemical Co., Ltd.: epoxy group Silane compound, EP4088L manufactured by Shin-Etsu Chemical Co., Ltd.: Epoxy resin having a dicyclopentadiene skeleton, SC-2050MB manufactured by ADEKA: Filler, silica, manufactured by Admatex Co., Ltd.

<Preparation of epoxy resin composition>
Examples 1 to 11 and Comparative Examples 1 to 15
Epoxy resin compositions were prepared by blending each component based on the formulations listed in Tables 1 to 3. Specifically, first, components other than the polymerization initiator were mixed into a flask. Next, 50 parts by mass of methyl ethyl ketone and 50 parts by mass of toluene were added and dissolved with stirring at room temperature. Then, a polymerization initiator was added and stirred at room temperature. In this way, a varnish of an epoxy resin composition was prepared.

<Evaluation>
[Compatibility]
The state of the varnish of the epoxy resin composition of each Example and each Comparative Example was visually observed.
Compatibility was evaluated based on the following criteria. The results are shown in Tables 1 to 3.
{standard}
Good: The varnish of the epoxy resin composition was transparent.
×: White turbidity and/or aggregates were observed in the varnish of the epoxy resin composition.

[Coatability]
The varnish of the epoxy resin composition of each example and each comparative example was applied to PET film (release-treated PET film (trade name: PET75x1H-ASI5, manufactured by Nipper Co., Ltd., thickness: : 75 μm, base film) and dried in a nitrogen purge oven at 80° C. for 3 minutes to form a coating film (thickness: 15 μm). Coatability was evaluated based on the following criteria. The results are shown in Tables 1 to 3.
{standard}
○: Coating streaks and/or repellency were not observed.
×: Coating streaks and/or repelling were observed.

[Releasability]
The peelability was evaluated based on the following criteria. The results are shown in Tables 1 to 3.
{standard}
Good: The resin alone could be removed from the PET film.
×: The resin alone could not be removed from the PET film. Or the resin film is damaged due to scratches, holes, etc.

[Low moisture permeability]
In the peelability evaluation, the peeled coating film was subjected to a 24-hour moisture permeability test in a constant temperature and humidity chamber at a temperature of 60°C and a relative humidity of 95% RH, in accordance with the JIS Z 0208 moisture permeability test (cup method). was carried out and the moisture permeability was measured. The lower the moisture permeability, the better the low moisture permeability. The results are shown in Tables 1 to 3. In addition, in Table 2 and Table 3, in the case where the coating film could not be peeled off in the coating property evaluation, it is described as "unmeasurable". Furthermore, even if the coating cannot be peeled off, if there are small holes and/or cracks, the moisture permeability cannot be measured and is described as "unmeasurable."

Note that although the above invention has been provided as an exemplary embodiment of the present invention, this is merely an example and should not be interpreted in a limiting manner. Variations of the invention that are obvious to those skilled in the art are intended to be within the scope of the following claims.

The epoxy resin composition, sealing material, and image display device of the present invention can be suitably used, for example, in the production of organic EL displays.

Claims

Contains an epoxy resin, a styrene viscosity modifier, polyisobutylene, and a compatibilizer,
The compatibilizer has a diblock structure including a styrene-derived structure and an olefin-derived structure,
The blending ratio of the compatibilizer is 30 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of polyisobutylene,
In the epoxy resin composition, the blending ratio of the compatibilizer is 80 parts by mass or more and 350 parts by mass or less with respect to 100 parts by mass of the styrene-based viscosity modifier.
A sealing material comprising a cured product of the epoxy resin composition according to claim 1.
An image display device comprising an optical element and the sealing material according to claim 2, which seals the optical element.