KR20210018320A - Image display device encapsulant - Google Patents

Abstract

A resin component and a curing agent are contained in the image display device sealing material. The resin component contains a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin.

Description

Image display device encapsulant

The present invention relates to an image display device sealing material.

As an image display device including an optical element, for example, a liquid crystal display, an organic EL display, and the like are known. In such an image display device, the optical element is sealed with a sealing member in order to suppress deterioration of the optical element due to moisture in the atmosphere or the like.

The sealing member is formed, for example, by embedding the optical element in the sealing composition and then curing the sealing composition. Therefore, in order to impart the required performance for various uses to the sealing member, various compositions of the composition for sealing have been studied.

For example, a curable resin composition for sealing an organic electroluminescent display element containing a phenoxy resin, a cycloalkene oxide-type alicyclic epoxy compound, and a curing agent has been proposed (for example, see Patent Document 1).

International Publication No. 2015/129670

However, when the sealing member formed of the curable resin composition for sealing an organic electroluminescent display element described in Patent Document 1 is used, for example, in a touch panel of an organic EL display, since the dielectric constant is high, noise caused by the sealing member is prevented. As a result, a malfunction may occur in the touch panel.

The present invention provides an image display device encapsulant capable of forming a sealing member having a relatively low dielectric constant and ensuring transparency.

The present invention [1] contains a resin component and a curing agent, and the resin component contains an image display device sealing material containing an epoxy resin containing a bisphenol alkyl substituted cyclohexane skeleton.

In the present invention [2], the resin component further contains a hydrogenated bisphenol A skeleton-containing epoxy resin, the image display device sealing material according to [1].

In the present invention [3], the resin component further contains a biphenyl skeleton-containing epoxy resin having a weight average molecular weight of 800 or more and 100,000 or less, the image display device sealing material according to [1] or [2], have.

According to the image display device encapsulant of the present invention, since the resin component contains an epoxy resin containing a bisphenol alkyl substituted cyclohexane skeleton, a sealing member having a relatively low dielectric constant and ensuring transparency can be formed.

1 is a side cross-sectional view of a sealing sheet as an embodiment of the sealing sheet for an image display device of the present invention.
FIG. 2 is a side cross-sectional view of an organic EL display with a touch sensor as an embodiment (a mode having an in-cell structure or an on-cell structure) of an image display device including a sealing member formed of the sealing layer shown in FIG. 1.
3 is a side cross-sectional view of an organic EL display with a touch sensor as another embodiment (a mode having an out-cell structure) of an image display device.

<First embodiment>

The image display device sealing material of the present invention (hereinafter, referred to as a sealing material) is a sealing resin composition (encapsulating resin composition for an image display device) for sealing an optical element included in an image display device described later, and is cured. It is a curable resin composition which forms a sealing member mentioned later by this. The encapsulant contains a resin component and a curing agent.

(1) resin component

The resin component contains a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin as an essential component.

(1-1) Bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin

The bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin has, for example, a plurality of bisphenol alkyl substituted cyclohexane skeletons and a plurality of epoxy groups (polyfunctional (including bifunctional) type epoxy resin). The bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin preferably has a molecular chain containing a plurality of bisphenol alkyl substituted cyclohexane skeletons, and an epoxy group bonded to both ends of the molecular chain (bifunctional epoxy resin). .

In the bisphenol alkyl substituted cyclohexane skeleton, a cyclohexane ring substituted with one or more alkyl groups (R ¹ ) is bonded to a carbon atom connecting two benzene rings as shown in the following formula (1).

The bisphenol alkyl substituted cyclohexane skeleton is more preferably represented by the following formula (1).

Equation (1)

[In formula (1), I, II, and III are structural units, each of I and III represents a terminal unit, and II represents a repeating unit. R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.]

As the alkyl group represented by R ¹ in the above formula (1), for example, a linear alkyl group having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl), a branched alkyl group having 3 to 6 carbon atoms ( For example, isopropyl, isobutyl, tert-butyl, etc.) etc. are mentioned.

Among the alkyl groups represented by R ¹ in the above formula (1), preferably a linear alkyl group having 1 to 6 carbon atoms is mentioned, and more preferably a methyl group is used. In addition, a plurality of R ^1s in the above formula (1) may be the same or different.

In the formula (1), of the plurality of R ^1s , at least one R ¹ is an alkyl group, preferably two or more R ^1s are an alkyl group, and more preferably three R ^1s are an alkyl group. On the other hand, among a plurality of R ^1s , R ¹ other than an alkyl group is a hydrogen atom.

Further, in the above formula (1), the hydrogen atom of the benzene ring may be substituted with the above alkyl group, but is preferably not substituted with the above alkyl group.

Among such bisphenol alkyl substituted cyclohexane skeletons, particularly preferably, a bisphenol trimethylcyclohexane skeleton-containing epoxy resin represented by the following formula (2) (hereinafter, referred to as a bisphenol TMC skeleton-containing epoxy resin) is mentioned.

Equation (2)

[In formula (2), I, II and III are structural units, each of I and III represents a terminal unit, and II represents a repeating unit. R ¹ is R ¹ and agreed in the formula (1).]

The bisphenol TMC skeleton-containing epoxy resin represented by the above formula (2) is bisphenol TMC (4,4'-(3,5,5-trimethyl-1,1-cyclohexanediyl)bis(phenol)) and epi As a chlorohydrin copolymer, it has a molecular chain including a plurality of bisphenol TMC skeletons and a glycidyl ether unit bonded to both ends of the molecular chain (bifunctional epoxy resin).

The bisphenol TMC skeleton-containing epoxy resin represented by the above formula (2) is a solid at room temperature. On the other hand, "normal temperature solid" refers to a solid state that does not have fluidity at room temperature (23°C), and “normal temperature liquid state” refers to a liquid state that has fluidity at normal temperature (23°C) (the same applies hereinafter). .

In addition, the bisphenol alkyl substituted cyclohexane skeleton represented by the above formula (1) (bisphenol TMC skeleton-containing epoxy resin represented by the above formula (2)) may contain other structural units in addition to the structural units I to III. As another structural unit, for example, a polyol unit derived from a polyol having a divalent or higher value, a biphenyl unit derived from a biphenyl, and the like can be mentioned.

The weight average molecular weight (Mw) of the bisphenol alkyl substituted cyclohexane skeleton is, for example, 10,000 or more, preferably 12,000 or more, more preferably 15,000 or more, such as 200,000 or less, and preferably 150,000 or less. The weight average molecular weight (Mw) can be calculated|required by gel permeation chromatography (GPC) using polystyrene as a standard substance (the same applies hereafter).

The epoxy equivalent in the bisphenol alkyl substituted cyclohexane skeleton is, for example, 5,000 g/eq. Or more, preferably 6,000 g/eq. Or more, for example, 100,000 g/eq. Or less, preferably 75,000 g/eq. Below.

Such bisphenol TMC skeleton-containing epoxy resins may be used alone or in combination of two or more.

In the resin component, the content ratio of the bisphenol TMC skeleton-containing epoxy resin is, for example, 5% by mass or more, preferably 10% by mass or more, such as 60% by mass or less, preferably 50% by mass or less, More preferably, it is 40 mass% or less.

(1-2) Hydrogenated bisphenol A skeleton-containing epoxy resin

The resin component, as an optional component, preferably further contains a hydrogenated bisphenol A skeleton-containing epoxy resin.

The hydrogenated bisphenol A skeleton-containing epoxy resin is a hydrogenated product obtained by adding hydrogen to the bisphenol A skeleton-containing epoxy resin.

Hydrogenated bisphenol A skeleton-containing epoxy resin, for example, has a plurality of hydrogenated bisphenol A skeletons (specifically, 2,2'-biscyclohexylpropane skeleton) and a plurality of epoxy groups (polyfunctional (including bifunctional A) type epoxy resin). The hydrogenated bisphenol A skeleton-containing epoxy resin preferably has a molecular chain containing a plurality of hydrogenated bisphenol A skeletons and an epoxy group bonded to both ends of the molecular chain (bifunctional epoxy resin).

The hydrogenated bisphenol A skeleton-containing epoxy resin is more preferably a hydrogenated product of a bisphenol A skeleton-containing epoxy resin, which is a copolymer of bisphenol A and epichlorohydrin, and comprises a plurality of hydrogenated bisphenol A skeletons and a molecular chain. It has a glycidyl ether unit bonded to both ends of (bifunctional epoxy resin). The hydrogenated bisphenol A skeleton-containing epoxy resin is solid at room temperature.

The weight average molecular weight (Mw) of the hydrogenated bisphenol A skeleton-containing epoxy resin is, for example, 100 or more, preferably 150 or more, more preferably 200 or more, such as 1,000 or less, preferably 800 or less.

The epoxy equivalent in the hydrogenated bisphenol A skeleton-containing epoxy resin is, for example, 50 g/eq. Or more, preferably 150 g/eq. Above, for example, 500g/eq. Or less, preferably 400 g/eq. Below.

Such hydrogenated bisphenol A skeleton-containing epoxy resins may be used alone or in combination of two or more.

In the resin component, the content ratio of the hydrogenated bisphenol A skeleton-containing epoxy resin is, for example, 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, such as 80% by mass. It is below, Preferably it is 70 mass% or less.

In addition, the content ratio of the hydrogenated bisphenol A skeleton-containing epoxy resin is based on a total of 100 parts by mass of the biphenyl skeleton-containing epoxy resin (described later) having a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin and a weight average molecular weight of 800 or more and 100,000 or less, For example, it is 100 parts by mass or more, preferably 120 parts by mass or more, for example, 300 parts by mass or less, preferably 200 parts by mass or less.

(1-3) Biphenyl skeleton-containing epoxy resin

The resin component further contains, as an optional component, a biphenyl skeleton-containing epoxy resin preferably having a weight average molecular weight of 800 or more and 100,000 or less.

The biphenyl skeleton-containing epoxy resin has, for example, a plurality of biphenyl skeletons and a plurality of epoxy groups (multifunctional (including bifunctional) type epoxy resin). The biphenyl skeleton-containing epoxy resin preferably has a molecular chain containing a plurality of biphenyl skeletons and an epoxy group bonded to both ends of the molecular chain (bifunctional epoxy resin).

The biphenyl skeleton-containing epoxy resin is more preferably represented by the following formula (3).

Equation (3)

[In formula (3), IV, V, and VI are constituent units, each of IV and VI is a terminal unit, and V is a repeating unit. R ² represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.]

The biphenyl skeleton-containing epoxy resin represented by the above formula (3) is a copolymer of a dihydroxybiphenyl derivative and epichlorohydrin, and is bonded to a molecular chain containing a plurality of biphenyl skeletons and at both ends of the molecular chain. It has a glycidyl ether unit (bifunctional epoxy resin).

Examples of the alkyl group represented by R ² in the formula (3) include the same alkyl group as in R ^{1 in} the formula (1).

Among R ² in the formula (3), preferably, a hydrogen atom and a methyl group are exemplified.

In addition, a plurality of R ² in Formula (3) may be the same or different.

In the formula (3), of the plurality of R ² , R ² bonded to the 3rd and 5th positions of the benzene ring is preferably an alkyl group, more preferably a methyl group. On the other hand, the plurality of R ^2, R ² benzene ring 2 and a coupling on the top 6 is preferably a hydrogen atom.

In addition, the biphenyl-type phenoxy resin represented by the above formula (3) may contain other structural units in addition to the structural units IV to VI. As other structural units, for example, a polyol unit derived from a polyol having a divalent or higher value, a bisphenol unit derived from a bisphenol, and the like can be mentioned.

The weight average molecular weight (Mw) of the biphenyl skeleton-containing epoxy resin is 800 or more, preferably 1,000 or more, more preferably 2,000 or more, 100,000 or less, and preferably 90,000 or less.

The epoxy equivalent in the biphenyl skeleton-containing epoxy resin is, for example, 500 g/eq. Or more, preferably 1,000 g/eq. Above, for example, 20,000 g/eq. Or less, preferably 16,000 g/eq. Below.

Such biphenyl skeleton-containing epoxy resins may be used alone or in combination of two or more.

In the resin component, the content ratio of the biphenyl skeleton-containing epoxy resin is, for example, 5 mass% or more, preferably 10 mass% or more, such as 50 mass% or less, preferably 30 mass% or less. .

(1-4) Optional resin component

The resin component is other than the above-described specific resin component (bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin, hydrogenated bisphenol A skeleton-containing epoxy resin, biphenyl skeleton-containing epoxy resin) within the range that does not impair the effects of the present invention. It may contain a resin component.

As other resin components, for example, aliphatic hydrocarbon resins, styrene oligomers, bisphenol skeleton-containing epoxy resins (e.g., phenoxy resins, etc.), polyolefins (e.g., polyethylene, polybutadiene, etc.), polychloroprene , Polyamide, polyamideimide, polyurethane, polyether, polyester, silicone resin, and the like.

These other resin components may be used alone or in combination of two or more. In the resin component, the content ratio of the other resin components is, for example, 10 mass% or less, preferably 5 mass% or less.

In addition, the resin component particularly preferably contains no other resin component, and comprises a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin, a hydrogenated bisphenol A skeleton-containing epoxy resin, and a biphenyl skeleton-containing epoxy resin.

(2) hardener

The curing agent cures the encapsulant by polymerizing the resin component. The curing agent is not particularly limited as long as it can cure the encapsulant. As a curing agent, for example, an amine curing agent (e.g., diethylenetriamine, triethylenetetramine, tri(dimethylaminomethyl)phenol, etc.), an imidazole-based curing agent (e.g., 2-methylimida Sol, 2-ethyl-4-methylimidazole, etc.), acid anhydride curing agents (e.g., phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, etc.), thermal cationic curing agents, photo cationic curing agents, etc. Can be lifted. Such curing agents may be used alone or in combination of two or more.

Among the curing agents, preferably, a thermal cationic curing agent and a photo cationic curing agent are mentioned. That is, the curing agent preferably contains a thermal cationic curing agent and/or a photo cationic curing agent.

Each of the thermal cationic curing agent and the photo cationic curing agent is a polymerization of the above-described bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin, if necessary, the hydrogenated bisphenol A skeleton-containing epoxy resin and the biphenyl skeleton-containing epoxy resin. It is not particularly limited as long as it is a compound capable of initiating.

The thermal cationic curing agent is a thermal acid generator that generates an acid (cation) by heating. The thermal cationic curing agent is preferably a compound capable of initiating polymerization at a heat-resistant temperature of 120°C or lower, such as a display device (eg, an organic EL device).

As the thermal cationic curing agent, a known thermal cationic polymerization initiator can be used. Column as a cationic polymerization initiator, for _{^{example, AsF 6 -, SbF 6 -}} , PF 6 -, BF 4 -, B (C 6 F 5) 4 -, CF 3 SO 3 - , etc., sulfonium salt as for anions , Phosphonium salt, quaternary ammonium salt, diazonium salt, iodonium salt, and the like.

Among the thermal cationic curing agents, quaternary ammonium salts are preferably used.

The photo-cationic curing agent is a photo-acid generator that generates an acid (cation) by light irradiation. As the photo cationic curing agent, a known photo cationic polymerization initiator can be used. As an optical cationic curing agent, CPI-210S (made by San Apro), IK-1 (made by San Apro), etc. are mentioned, for example.

Such curing agents may be used alone or in combination of two or more.

The content ratio of the curing agent is, for example, 0.3 parts by mass or more, preferably 0.5 parts by mass or more, such as 10 parts by mass or less, and preferably 5 parts by mass or less, based on 100 parts by mass of the resin component.

(3) other additives

The encapsulant may contain a silane coupling agent, a leveling agent, a filler, a polymerization initiation aid, an anti-aging agent, a wettability improving agent, a surfactant, a plasticizer, an ultraviolet absorber, a preservative, an antibacterial agent, etc. .

<Image display device sealing sheet>

The above-described sealing material can be distributed as it is and can be used industrially, but is preferably distributed as an image display device sealing sheet from the viewpoint of handling properties.

Referring to Fig. 1, a sealing sheet 1 as an embodiment of the sealing sheet for an image display device of the present invention will be described.

As shown in FIG. 1, the sealing sheet 1 includes a base film 3, a sealing layer 2 made of the above sealing material, and a release film 4 in order in the thickness direction. On the other hand, the sealing sheet 1 is a component for manufacturing an image display device, and does not include a display element and a substrate on which the display element is mounted, specifically, the sealing layer 2, the base film 3, and It is a device which consists of the release film 4, distributes as a component alone, and can be used industrially.

In order to prevent foreign matter from adhering to the encapsulation layer 2, when storing the encapsulation sheet 1, it is preferable that the encapsulation layer 2 is protected by the base film 3 and the release film 4 . On the other hand, when using the sealing sheet 1, the base film 3 and the release film 4 are peeled off.

The sealing layer 2 is a dried product of the above sealing material, and has a film shape (flat plate shape). Specifically, the sealing layer 2 has a predetermined thickness, extends in a predetermined direction orthogonal to the thickness direction, and has a flat surface and a flat back surface.

In the sealing layer 2, the resin components described above are not reacting, and the sealing layer 2 contains these resin components in an uncured state.

The thickness of the sealing layer 2 is, for example, 1 µm or more, preferably 5 µm or more, for example, 100 µm or less, and preferably 30 µm or less.

The base film 3 can be peeled off on the back surface of the sealing layer 2 in order to support and protect the sealing layer 2 while the sealing sheet 1 is used for formation of the sealing member (described later). Are attached to each other. That is, the base film 3 is laminated on the back surface of the sealing layer 2 so as to cover the back surface of the sealing layer 2 at the time of shipment, transport, and storage of the sealing sheet 1, and the sealing sheet 1 ) Immediately before use, it is a flexible film that can be pulled off so as to be curved in a substantially U shape from the back surface of the sealing layer 2.

The base film 3 has a flat plate shape, specifically, has a predetermined thickness, extends in a predetermined direction orthogonal to the thickness direction, and has a flat surface and a flat back surface. The bonding surface (surface) of the base film 3 is peeled off as needed.

As the material of the base film 3, resin materials such as polyester (e.g., polyethylene terephthalate (PET), etc.), polyolefin (e.g., polyethylene, polypropylene, etc.) can be mentioned, Preferably, polyethylene terephthalate is used.

Among the base films 3, preferably, a film having moisture barrier properties or gas barrier properties is exemplified, more preferably a film made of polyethylene terephthalate. Although the thickness of the base film 3 is appropriately selected depending on the material of the film, it can be, for example, about 25 µm to 150 µm in terms of having followability with respect to a material to be sealed such as a display element.

The release film 4 is peelably adhered to the surface of the sealing layer 2 to protect the sealing layer 2 while the sealing sheet 1 is used for formation of the sealing member (described later). Has been. That is, the release film 4 is laminated on the surface of the sealing layer 2 so as to cover the surface of the sealing layer 2 at the time of shipment, transport, and storage of the sealing sheet 1, and the sealing sheet 1 ) Immediately before use, it is a flexible film that can be pulled off from the surface of the sealing layer 2 so as to be curved in a substantially U shape.

The release film 4 has a flat plate shape, specifically, a predetermined thickness, extends in a predetermined direction orthogonal to the thickness direction, and has a flat surface and a flat back surface. In addition, the bonding surface (back surface) of the release film 4 is subjected to a peeling treatment as necessary. As a material of the mold release film 4, the resin material similar to the base film 3 is mentioned, for example. Although the thickness of the release film 4 is appropriately selected depending on the material of the film, it can be, for example, about 25 µm to 150 µm from the point of having followability to a material to be sealed such as a display element.

<Production method of the image display device sealing sheet>

Next, the manufacturing method of the sealing sheet 1 is demonstrated.

In order to manufacture the sealing sheet 1, for example, the above sealing material is prepared, and the sealing material is applied to the surface of the base film 3 by a known method.

The sealing material is prepared by mixing the resin component, the curing agent, and the additive described above in the above ratio. In addition, in the manufacture of the sealing sheet 1, the sealing material is preferably diluted in an organic solvent to prepare a varnish of the sealing material.

The organic solvent is not particularly limited as long as it can uniformly disperse or dissolve the resin component and the curing agent. As an organic solvent, for example, aromatic hydrocarbons (e.g., benzene, toluene, xylene, etc.), ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ethers (e.g. , Dibutyl ether, tetrahydrofuran, dioxane, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, 1-methoxy-2-propanol, etc.), esters (e.g., ethyl acetate, acetic acid Butyl, etc.), nitrogen-containing compounds (for example, N-methylpyrrolidone, dimethylimidazolidinone, dimethylformaldehyde, etc.), and the like. Organic solvents can be used alone or in combination of two or more.

Each component can be mixed, for example, by dispersing with a ball mill, charging in a flask and stirring, or kneading with three rolls.

Moreover, as a coating method of a sealing material, screen printing, a dispenser, a coating roll, etc. are mentioned, for example.

Subsequently, the sealing material is dried and, if necessary, an organic solvent is volatilized to form a coating film.

The heating temperature is a temperature at which the encapsulant is dried without curing, and is, for example, 20°C or higher, preferably 90°C or higher, for example 120°C or lower, and preferably lower than 100°C. The heating time is, for example, 1 minute or more, preferably 2 minutes or more, such as 30 minutes or less, and preferably 15 minutes or less.

Thereby, the coating film is dried, and the sealing layer 2 formed from the sealing material is prepared. Next, the release film 4 is affixed to the surface of the sealing layer 2.

By the above, the sealing sheet 1 is manufactured.

<Manufacture of image display device>

Such a sealing sheet 1 is suitably used for sealing (display element optical element) of an image display device. Referring to Fig. 2, an organic EL display with a touch sensor (hereinafter, referred to as the organic EL display 10) as an embodiment of the image display device will be described.

On the other hand, in this embodiment, an organic EL display with a touch sensor is exemplified as the image display device, but the image display device is not particularly limited. Examples of the image display device include a liquid crystal display (including a liquid crystal display with a touch sensor), an organic EL display (including an organic EL display with a touch sensor) and the like.

The organic EL display 10 includes an element mounting unit 11, a sealing member 14, and a cover glass or a barrier film 15.

The element mounting unit 11 includes a substrate 13, an organic EL element 12 as an example of a display element, a barrier layer 16, and an electrode (not shown).

The substrate 13 supports the organic EL element 12. The substrate 13 preferably has flexibility.

The organic EL element 12 is a known organic EL element, and is mounted on the substrate 13. Although not shown, the organic EL element 12 includes a cathode reflective electrode, an organic EL layer, and an anode transparent electrode.

The barrier layer 16 covers the organic EL element 12 and suppresses moisture in the air from contacting the organic EL element 12. The barrier layer 16 includes a first inorganic barrier layer 17, a planarization layer 19, and a second inorganic barrier layer 18.

The first inorganic barrier layer 17 is disposed on the top and side surfaces of the organic EL element 12 so as to surround the organic EL element 12. As the material of the first inorganic barrier layer 17, for example, a metal oxide (for example, aluminum oxide, silicon oxide, copper oxide, etc.), a metal nitride (for example, aluminum nitride, silicon nitride, etc.) Can be lifted. The material for the first inorganic barrier layer 17 may be used alone or in combination of two or more. Among the materials of the first inorganic barrier layer 17, metal nitride is preferably used, and silicon nitride is more preferably used.

The planarization layer 19 is disposed on the upper surface of the first inorganic barrier layer 17. As the material of the planarization layer 19, a known resin material can be mentioned.

The second inorganic barrier layer 18 is disposed on the top and side surfaces of the planarization layer 19 so as to surround the planarization layer 19. As the material of the second inorganic barrier layer 18, a material similar to that of the first inorganic barrier layer 17 is exemplified.

Electrodes (not shown) constitute a sensor of an organic EL display with a touch sensor. An electrode (not shown) is positioned between the substrate 13 and the sealing member 14. For example, an electrode (not shown) may be located in the substrate 13 or on the organic EL element 12.

The sealing member 14 is a cured product of the sealing layer 2 (encapsulation material), and seals the organic EL element 12 coated on the barrier layer 16. The sealing member 14 is formed of the encapsulation layer 2 from which the base film 3 and the release film 4 are peeled off. Specifically, after the encapsulation layer 2 from which the base film 3 and the release film 4 are peeled off is affixed to the substrate 13 so as to bury the organic EL element 12 covered with the barrier layer 16 , The cover glass or the barrier film 15 is affixed on the upper surface of the sealing layer 2, and after that, the sealing layer 2 is hardened. Thereby, the sealing member 14 is formed.

The dielectric constant of the sealing member 14 is, for example, 3.0 or more, preferably 3.2 or more, for example, less than 3.80, and preferably 3.70 or less. On the other hand, the dielectric constant can be measured according to the method described in Examples to be described later.

When the dielectric constant of the sealing member 14 is more than the above lower limit, the degree of freedom of material selection can be improved. If the dielectric constant of the sealing member 14 is less than or equal to the above upper limit, it is possible to suppress the occurrence of malfunction in an organic EL display with a touch sensor or the like.

The moisture permeability of the sealing member 14 is, for example, 20 g/m ² ·24 h or more, for example, less than 45 g/m ² ·24 h. On the other hand, the moisture permeability can be measured according to the method described in Examples to be described later.

When the moisture permeability of the sealing member 14 is less than or equal to the above upper limit, deterioration of the optical element sealed by the sealing member 14 can be suppressed.

The cover glass or barrier film 15 is disposed on the upper surface of the sealing member 14. Although not shown, the cover glass or the barrier film 15 is provided with a glass plate and an electrode which is provided on the lower surface of a glass plate and constitutes a sensor of an organic EL display with a touch sensor.

In such an organic EL display 10, an in-cell structure in which the organic EL element 12 is disposed between two electrodes constituting the sensor, or one of the two electrodes constituting the sensor is on the organic EL element 12. It has an on-cell structure that is arranged.

<action effect>

By the way, the sealing member of a liquid crystal display is provided in a frame shape so that it may surround the periphery of the liquid crystal arrange|positioned between a base material and a glass plate, for example. In contrast, the sealing member of the organic EL display is provided so that the organic EL element is embedded therein, as shown in Fig. 2. Therefore, the sealing member of the organic EL display has a greater influence of the dielectric constant than the sealing member of the liquid crystal display, and it is desired to reduce the dielectric constant.

On the other hand, the sealing member of an organic EL display is not required to have a low dielectric constant as required for a sealing member of an ordinary semiconductor component.

The present inventors have studied various compositions of the resin component, and the resin component of the sealing material contains a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin, thereby achieving a reduction in the dielectric constant in the sealing member, and high transparency. The present invention was completed by finding the knowledge that can be secured.

In the above sealing material, since the resin component contains an epoxy resin containing a bisphenol alkyl substituted cyclohexane skeleton, in the sealing member, the dielectric constant can be reduced to a range required for an image display device (especially an organic EL display), while High transparency required for display devices (especially organic EL displays) can be ensured.

Moreover, as shown in FIG. 1, the sealing sheet 1 has a sealing layer 2 made of a sealing material. Therefore, it is possible to improve the handleability of the sealing material. Further, in the sealing member, while the dielectric constant can be reduced, high transparency can be secured.

<Second Embodiment>

Next, a second embodiment of the sealing material will be described.

In the first embodiment described above, the resin component preferably contains the above-described bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin (bisphenol TMC skeleton-containing epoxy resin) and the above-described biphenyl skeleton-containing epoxy resin. Is not limited to this.

In the second embodiment, the resin component is a bisphenol alkyl substituted cyclohexane skeleton-containing monomer (e.g., bisphenol TMC, etc.) and a biphenyl skeleton-containing epoxy monomer (e.g., tetramethylbiphenyl diglycidyl ether, etc.). ) Contains a copolymer. The resin component preferably contains a copolymer of bisphenol TMC and tetramethylbiphenyl diglycidyl ether.

Such a copolymer has a plurality of bisphenol alkyl substituted cyclohexane skeletons (bisphenol TMC skeletons), a plurality of biphenyl skeletons, and a plurality of epoxy groups (polyfunctional (including bifunctional) type epoxy resin). Therefore, such a copolymer corresponds to a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin (bisphenol TMC skeleton-containing epoxy resin), and more specifically, to a bisphenol TMC skeleton-biphenyl skeleton-containing epoxy resin.

Such a copolymer, particularly preferably, has a molecular chain including a plurality of bisphenol TMC skeletons and a plurality of biphenyl skeletons, and an epoxy group (glycidyl ether unit) bonded to both ends of the molecular chain (bifunctional Mold epoxy resin).

In the resin component, the content ratio of the copolymer of the bisphenol alkyl substituted cyclohexane skeleton-containing monomer and the biphenyl skeleton-containing epoxy monomer is, for example, 10 mass% or more, preferably 30 mass% or more, for example, It is 70 mass% or less, Preferably it is 60 mass% or less, More preferably, it is 50 mass% or less.

In addition, in the second embodiment, the resin component preferably contains a hydrogenated bisphenol A skeleton-containing epoxy resin, similarly to the above. On the other hand, the resin component may contain a biphenyl skeleton-containing epoxy resin, but preferably does not contain a biphenyl skeleton-containing epoxy resin.

That is, in the second embodiment, the resin component is preferably composed of a copolymer of a bisphenol alkyl substituted cyclohexane skeleton-containing monomer and a biphenyl skeleton-containing epoxy monomer, and a hydrogenated bisphenol A skeleton-containing epoxy resin.

Also with such a second embodiment, the same effects as those of the first embodiment can be exhibited.

In addition, the resin component is a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin, and the bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin in the first embodiment (preferably, the bisphenol TMC skeleton represented by the above formula (2) It may contain a copolymer of the epoxy resin containing) and the epoxy resin containing the biphenyl skeleton in the first embodiment (preferably the epoxy resin containing the biphenyl skeleton represented by the above formula (3)).

<modification example>

In the modified example, the same reference numerals are used for members and processes similar to those in the first embodiment, and detailed descriptions thereof are omitted.

As shown in Fig. 1, the sealing sheet 1 includes the sealing layer 2, the base film 3, and the release film 4, but the image display device sealing sheet is not limited thereto. If the image display device sealing sheet is provided with the sealing layer 2, the base film 3 and/or the release film 4 may not be provided. That is, the image display device sealing sheet may be constituted by only the sealing layer 2, and may be provided with either the sealing layer 2 and the base film 3 and the release film 4.

As shown in Fig. 2, the organic EL display 10 includes a barrier layer 16, but is not limited thereto. The organic EL display 10 does not need to have the barrier layer 16.

In addition, the organic EL display 10 has an in-cell structure in which the organic EL element 12 is disposed between two electrodes constituting a sensor, or an on-cell structure in which one of the two electrodes is disposed on the organic EL element 12 It has a structure, but is not limited to this.

For example, as shown in FIG. 3, the organic EL display 20 may have an outcell structure in which two electrodes constituting a sensor are disposed above the sealing member 14. The organic EL display 20 includes the element mounting unit 11 described above, the sealing member 14 described above, and the sensor unit 25.

The sensor unit 25 is disposed on the sealing member 14. The sensor unit 25 is provided with electrodes constituting a sensor of an organic EL display with a touch sensor. On the other hand, in the organic EL display 20, the substrate 13 does not have an electrode.

Also about each of the above-described modified examples, the same effects as those of the above-described embodiment are exhibited. The above-described embodiments and modifications can be appropriately combined.

Example

Examples are shown below to describe the present invention more specifically, but the present invention is not limited thereto. Specific values such as mixing ratios (contents ratio), physical properties, and parameters used in the following description are described in the above ``Specific Contents for Carrying out the Invention'', and the corresponding mixing ratios (contents ratio) , Physical properties, parameters, etc. can be replaced with the upper limit (a value defined as "less than" or "less than") or a lower limit (a value defined as "above" or "exceeding"). In addition, "part" and "%" are based on mass unless otherwise specified.

Synthesis Example 1

In a flask equipped with a stirrer, thermometer, nitrogen inlet pipe and cooling pipe, 100 parts by mass of bisphenol TMC and 140 parts by mass of bisphenol TMC diglycidyl ether (ratio of moles of epoxy group/moles of phenolic hydroxyl group = 1.03), and 15 parts by mass of cyclohexanone was added as a reaction solvent, and the temperature was raised to 100°C in a nitrogen atmosphere. Subsequently, as a catalyst, 0.1 parts by mass of methyl triphenylphosphonium bromide (TMP) was added to the flask, and the internal temperature of the flask was raised to 140°C. As the reaction proceeded, the reaction solution began to thicken, so 75 parts by mass of cyclohexanone was added to the reaction solution and reacted for 12 hours. On the other hand, the reaction temperature was 140 to 145°C when the nonvolatile content was 80% by mass or more, and the temperature was refluxed thereafter. After completion of the reaction, 200 parts by mass of methyl ethyl ketone was added to the reaction solution to obtain a resin varnish containing a bisphenol TMC skeleton-containing epoxy resin.

Synthesis Example 2

In a flask equipped with a stirrer, thermometer, nitrogen inlet tube and cooling tube, 100 parts by mass of bisphenol TMC and 118 parts by mass of tetramethylbiphenyl diglycidyl ether (ratio of number of moles of epoxy group/number of moles of phenolic hydroxyl group = 1.03) Wow, 15 parts by mass of cyclohexanone was added as a reaction solvent, and the temperature was raised to 100°C in a nitrogen atmosphere. Subsequently, after adding 0.1 parts by mass of TMP as a catalyst to the flask, the internal temperature of the flask was raised to 140°C. As the reaction proceeded, the reaction solution began to thicken, so 75 parts by mass of cyclohexanone was added to the reaction solution and reacted for 12 hours. On the other hand, the reaction temperature was 140 to 145°C when the non-volatile content was 80% or more, and the reflux temperature thereafter. After completion of the reaction, 200 parts by mass of methyl ethyl ketone was added to the reaction solution to obtain a resin varnish containing a bisphenol TMC skeleton-containing epoxy resin (bisphenol TMC skeleton-biphenyl skeleton-containing epoxy resin).

Examples 1 and 2

The bisphenol TMC skeleton-containing epoxy resin obtained in each of the synthesis examples shown in Table 1, and a hydrogenated bisphenol A skeleton-containing epoxy resin (trade name: YX8000, manufactured by Mitsubishi Chemical, weight average molecular weight: 352, epoxy equivalent: 205 g/eq.), and bisphenol A skeleton-containing epoxy resin. Phenyl skeleton-containing epoxy resin (trade name: YX6954BH30, manufactured by Mitsubishi Chemical Corporation, in the formula (3), R ² represents a hydrogen atom and a methyl group, a weight average molecular weight: 39,000, an epoxy equivalent: 10,000 to 16,000 g/eq.), and a thermal cation The system hardening agent (trade name: CXC-1612, manufactured by King Industries) was mixed by the formulation shown in Table 1 (in terms of solid content) to prepare a sealing material.

Examples 3 and 4

A sealing material was prepared in the same manner as in Examples 1 and 2, except that the thermal cationic curing agent was changed to a photocationic curing agent (brand name: CPI-210S, manufactured by San Apro).

Comparative Example 1

Bisphenol type phenoxy resin (trade name: jER4275, manufactured by Mitsubishi Chemical Co., Ltd., containing bisphenol A skeleton and bisphenol F skeleton, epoxy equivalent: 8,400 to 9,200 g/eq.), and cycloalkene oxide type epoxy resin (trade name: Celoxide 2021P, 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexane carboxylate, molecular weight: 252.3, epoxy equivalent: 128 to 145 g/eq.) and solid epoxy resin (trade name: jER4005P, manufactured by Mitsubishi Chemical, Epoxy Equivalent weight: 1070 g/eq.) and a thermal cationic curing agent (brand name: CXC-1612, manufactured by King Industries) were mixed by the formulation shown in Table 1 (in terms of solid content) to prepare a sealing material.

Comparative Example 2

Bisphenol-type phenoxy resin is a biphenyl skeleton-containing epoxy resin (trade name: YX6954BH30, manufactured by Mitsubishi Chemical Co., Ltd., R ² in the formula (3) is a hydrogen atom and a methyl group, weight average molecular weight: 39,000, epoxy equivalent: 10,000 to 16,000 g/ eq.), it carried out similarly to Comparative Example 1, and prepared the sealing material.

Comparative Example 3

Bisphenol-type phenoxy resin (trade name: jER4275, manufactured by Mitsubishi Chemical, containing bisphenol A skeleton and bisphenol F skeleton, epoxy equivalent: 8,400 to 9,200 g/eq.), and hydrogenated bisphenol A skeleton-containing epoxy resin (trade name: YX8000, Mitsubishi A chemical company make, weight average molecular weight: 352, epoxy equivalent: 205 g/eq.) and a thermal cationic initiator (brand name: CXC-1612, made by KingIndustries) were mixed by the formulation shown in Table 1 (in terms of solid content), and a sealing material was Prepared.

<Evaluation>

·permittivity

After coating the sealing material of each Example and each comparative example on a PET film (release-treated PET film, brand name: PUREX A53, manufactured by Teijin DuPont Film, thickness: 38 μm, base film) by a coating machine, nitrogen purge oven Then, it dried at 90 degreeC for 3 minutes, and the sealing layer of 15 micrometers in thickness was formed.

Next, a PET film (release-treated PET film, brand name: Purex A31, Teijin DuPont film company make, thickness: 38 μm, release film) was bonded to the sealing layer at 80°C by a thermal laminator.

By the above, a sealing sheet provided with a base film, a sealing layer, and a release film was prepared. This was repeated to prepare two sealing sheets for each of the Examples and Comparative Examples. And in the two sealing sheets corresponding to the same Example or Comparative Example, after the release film was peeled from the sealing layer, the two sealing layers were bonded to each other in the thickness direction, and their thickness was set to 30 μm.

Subsequently, the two sealing layers bonded together were peeled off the base film on one side and cured at 100° C. for 1 hour, and then the base film on the other side was peeled off from the sealing layer after curing to obtain a measurement sample. The dielectric constant of the obtained sample at 100 kHz was measured by an automatic balancing bridge method using an LCR meter HP4284A (manufactured by Azirent Technologies).

And the permittivity was evaluated according to the following criteria. The results are shown in Table 1.

○: less than 3.80

×: 3.80 or more.

·Permeability

In the same manner as in the evaluation of the above dielectric constant, sealing sheets of each of the examples and each of the comparative examples were prepared. And after peeling the release film from the sealing layer, the sealing layer was cured at 100 degreeC for 1 hour.

Then, the base film was peeled from the sealing layer after curing to obtain a sample for measurement. The moisture permeability (moisture permeability) of the obtained sample was measured under conditions of 60°C and 90%RH in accordance with JIS Z0208. Thereafter, the film thickness of the sample used for the measurement was converted into a value when the thickness of the sample was 100 μm.

And the moisture permeability was evaluated according to the following criteria. The results are shown in Table 1.

○: less than 45g/m ² ·24h

△: 45g/m ² ·24h or more.

In addition, although the said invention was provided as an exemplary embodiment of this invention, this is only a mere illustration and should not be interpreted limitedly. Modification examples of the present invention that are apparent by those skilled in the art are included in the later claims.

The image display device sealing material of the present invention is suitably used as a sealing material for various image display devices, specifically, as a sealing material for a liquid crystal display and an organic EL display.

1 bag sheet
2 encapsulation layer

Claims (3)

Contains a resin component and a hardener,
The said resin component contains a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin, The image display device sealing material characterized by the above-mentioned. The method of claim 1,
The said resin component further contains a hydrogenated bisphenol A skeleton-containing epoxy resin, The image display device sealing material characterized by the above-mentioned. The method of claim 1,
The resin component further contains a biphenyl skeleton-containing epoxy resin having a weight average molecular weight of 800 or more and 100,000 or less.

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