JP2019206717A - Image display device sealing material - Google Patents

Abstract

To provide an image display device sealing material capable of forming a seal member that has a relatively low dielectric constant and ensures transparency.SOLUTION: An image display device sealing material contains a resin component and a curing agent, the resin component containing a bisphenol alkyl substituted cyclohexane skeleton-containing epoxy resin. A sealing sheet 1 produced using the image display device sealing material has a sealing layer 2, a base film 3, and a release film 4.SELECTED DRAWING: Figure 1

Description

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

  As an image display device provided with 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 prevent the optical element from being deteriorated by moisture in the atmosphere.

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

  For example, a curable resin composition for sealing an organic electroluminescence 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, the seal member formed from the curable resin composition for sealing an organic electroluminescence display element described in Patent Document 1 has a high dielectric constant when used for a touch panel of an organic EL display, for example. The touch panel may malfunction due to noise caused by the members.

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

  This invention [1] contains the resin component and the hardening | curing agent, The said resin component contains the image display apparatus sealing material containing the bisphenol alkyl substituted cyclohexane frame containing epoxy resin.

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

  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, and the image display device sealing according to the above [1] or [2] Contains wood.

  According to the image display device sealing material of the present invention, since the resin component contains the bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin, it is possible to form a seal member having a relatively low dielectric constant and ensuring transparency.

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

<First Embodiment>
An image display device sealing material (hereinafter referred to as a sealing material) of the present invention is a sealing resin composition (sealing resin composition for an image display device) for sealing an optical element included in an image display device described later. It is a curable resin composition that forms a seal member to be described later by curing. The sealing material 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 (multifunctional (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, as shown in the following formula (1), a cyclohexane ring substituted with one or more alkyl groups (R ¹ ) is bonded to a carbon atom connecting two benzene rings.

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

Formula (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. ]
Examples of the alkyl group represented by R ^{1 in the} above formula (1) include, for example, a linear alkyl group having 1 to 6 carbon atoms (for example, methyl, ethyl, propyl, butyl, pentyl, hexyl), and a branched chain having 3 to 6 carbon atoms. An alkyl group (for example, isopropyl, isobutyl, tert-butyl, etc.) and the like can be mentioned.

Among the alkyl groups represented by R ^{1 in the} above formula (1), a linear alkyl group having 1 to 6 carbon atoms is preferable, and a methyl group is more preferable. Moreover, several R < ¹ > of the said Formula (1) may mutually be same, and may differ.

In the above formula (1), among the plurality of R ^1, at least one R ¹ is an alkyl group, preferably a two or more R ¹ is an alkyl group, more preferably, three of R ¹ is an alkyl It is a group. Of the plurality of R ^1, R ¹ other than alkyl groups are hydrogen atoms.

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

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

Formula (2)

[In Formula (2), I, II, and III are structural units, each of I and III shows a terminal unit, and II shows a repeating unit. R ¹ has the same meaning as ^{R 1} in the formula (1). ]
The bisphenol TMC skeleton-containing epoxy resin represented by the above formula (2) includes bisphenol TMC (4,4 ′-(3,5,5-trimethyl-1,1-cyclohexanediyl) bis (phenol)) and epichlorohydride. It is a copolymer with phosphorus, and has a molecular chain containing a plurality of bisphenol TMC skeletons and glycidyl ether units 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 solid at room temperature. “Normal temperature solid” means a solid state having no fluidity at normal temperature (23 ° C.), and “normal temperature liquid” means a liquid state having fluidity at normal temperature (23 ° C.). (The same applies hereinafter).

  The bisphenol alkyl-substituted cyclohexane skeleton represented by the above formula (1) (the 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. it can. Examples of the other structural unit include a polyol unit derived from a divalent or higher polyol and a biphenyl unit derived from biphenyl.

The weight average molecular weight (M _w ) 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, for example 200,000 or less, preferably 150 , 000 or less. The weight average molecular weight (M _w ) can be determined by gel permeation chromatography (GPC) using polystyrene as a standard substance (the same applies hereinafter).

  The epoxy equivalent in the bisphenol alkyl-substituted cyclohexane skeleton is, for example, 5,000 g / eq. Or more, preferably 6,000 g / eq. As described above, for example, 100,000 g / eq. Hereinafter, preferably, 75,000 g / eq. It is as follows.

  Such bisphenol TMC skeleton-containing epoxy resins can 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, for example 60% by mass or less, preferably 50% by mass or less, more preferably 40% by mass. It is below mass%.

(1-2) Hydrogenated bisphenol A skeleton-containing epoxy resin The resin component preferably further contains a hydrogenated bisphenol A skeleton-containing epoxy resin as an optional component.

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

  The hydrogenated bisphenol A skeleton-containing epoxy tree has, for example, a plurality of hydrogenated bisphenol A skeletons (specifically, 2,2′-biscyclohexylpropane skeleton) and a plurality of epoxy groups (multifunctional (bifunctional). Including 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 tree is more preferably a hydrogenated product of a bisphenol A skeleton-containing epoxy resin that is a copolymer of bisphenol A and epichlorohydrin, and includes a plurality of hydrogenated bisphenol A skeletons. It has a molecular chain and a glycidyl ether unit bonded to both ends of the molecular chain (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, for example, 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. As described above, for example, 500 g / eq. Hereinafter, preferably 400 g / eq. It is as follows.

  Such hydrogenated bisphenol A skeleton-containing epoxy resins can 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, for example, 80% by mass or less, preferably 70 mass% or less.

  Further, the content ratio of the hydrogenated bisphenol A skeleton-containing epoxy resin is 100 parts by mass in total of the bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin and the biphenyl skeleton-containing epoxy resin having a weight average molecular weight of 800 or more and 100,000 or less (described later) On the other hand, it is 100 mass parts or more, for example, Preferably, it is 120 mass parts or more, for example, 300 mass parts or less, Preferably, it is 200 mass parts or less.

(1-3) Biphenyl skeleton-containing epoxy resin The resin component preferably further contains a biphenyl skeleton-containing epoxy resin having a weight average molecular weight of 800 or more and 100,000 or less as an optional component.

  The biphenyl skeleton-containing epoxy resin has, for example, a plurality of biphenyl skeletons and a plurality of epoxy groups (polyfunctional (including bifunctional) type epoxy resins). 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).

Formula (3)

[In Formula (3), IV, V, and VI are structural units, each of IV and VI represents a terminal unit, and V represents 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 binds to a molecular chain including a plurality of biphenyl skeletons and both ends of the molecular chain. It has a glycidyl ether unit (bifunctional epoxy resin).

As an alkyl group shown as R < ² > of the said Formula (3), the alkyl group similar to R < ¹ > of the said Formula (1), etc. are mentioned, for example.

Of R ^{2 in} the above formula (3), a hydrogen atom and a methyl group are preferable. Moreover, several R < ² > of Formula (3) may mutually be same, and may differ.

In the above formula (3), among the plurality of R ^2, R ² is attached to the 3 and 5 positions of the benzene ring is preferably an alkyl group, more preferably a methyl group. Of the plurality of R ^2, R ² is attached to the 2-position and 6-position of the benzene ring is preferably a hydrogen atom.

  Moreover, the biphenyl type phenoxy resin represented by the above formula (3) can contain other structural units in addition to the structural units IV to VI. Examples of other structural units include a polyol unit derived from a divalent or higher valent polyol and a bisphenol unit derived from bisphenol.

The weight average molecular weight (M _w ) of the biphenyl skeleton-containing epoxy resin is 800 or more, preferably 1,000 or more, more preferably 2,000 or more and 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. As described above, for example, 20,000 g / eq. Hereinafter, preferably, 16,000 g / eq. It is as follows.

  Such biphenyl skeleton-containing epoxy resins can 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% by mass or more, preferably 10% by mass or more, for example, 50% by mass or less, preferably 30% by mass or less.

(1-4) Optional resin component The resin component is a specific resin component (bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin, hydrogenated bisphenol A skeleton-containing epoxy resin, biphenyl skeleton) as long as the effects of the present invention are not impaired. Resin components other than (containing epoxy resin) can be contained.

  Other resin components include, for example, aliphatic hydrocarbon resins, styrene oligomers, bisphenol skeleton-containing epoxy resins (for example, phenoxy resins), polyolefins (for example, polyethylene, polybutadiene, etc.), polychloroprene, polyamide, polyamideimide, polyurethane , Polyether, polyester, silicone resin and the like. These other resin components can be used alone or in combination of two or more. In the resin component, the content ratio of the other resin component is, for example, 10% by mass or less, preferably 5% by mass or less.

  The resin component particularly preferably does not contain other resin components, and consists of 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) Curing agent The curing agent polymerizes the resin component to cure the sealing material. The curing agent is not particularly limited as long as the sealing material can be cured. Examples of the curing agent include amine-based curing agents (for example, diethylenetriamine, triethylenetetramine, tri (dimethylaminomethyl) phenol), imidazole-based curing agents (for example, 2-methylimidazole, 2-ethyl-4-methylimidazole, etc.). ), Acid anhydride curing agents (for example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, etc.), thermal cationic curing agents, photocationic curing agents, and the like. Such curing agents can be used alone or in combination of two or more.

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

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

  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 (for example, an organic EL device).

A known thermal cationic polymerization initiator can be used as the thermal cationic curing agent. As the thermal cationic polymerization initiator, for example, a sulfonium salt having AsF ₆ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , B (C ₆ F ₅ ) ₄ ⁻ , CF ₃ SO ₃ ⁻ or the like as a counter anion, Examples thereof include phosphonium salts, quaternary ammonium salts, diazonium salts, iodonium salts and the like.

  Among the thermal cationic curing agents, preferably, a quaternary ammonium salt is used.

  The photocationic curing agent is a photoacid generator that generates an acid (cation) by light irradiation. As the photocationic curing agent, a known photocationic polymerization initiator can be used. Examples of the photocationic curing agent include CPI-210S (manufactured by San Apro) and IK-1 (manufactured by San Apro).

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

  The content of the curing agent is, for example, 0.3 parts by mass or more, preferably 0.5 parts by mass or more, for example, 10 parts by mass or less, preferably 5 parts by mass or less with respect to 100 parts by mass of the resin component. is there.

(3) Other additives The sealing material is optionally added as other additives such as silane coupling agents, leveling agents, fillers, polymerization initiation aids, anti-aging agents, wettability improvers, and surface active agents. An agent, a plasticizer, an ultraviolet absorber, an antiseptic, an antibacterial agent and the like may be contained in an appropriate ratio.

<Image display device sealing sheet>
The above-described sealing material can be distributed as it is, and is an industrially usable product, but is preferably distributed as an image display device sealing sheet from the viewpoint of handleability.

  With reference to FIG. 1, the sealing sheet 1 as one Embodiment of the image display apparatus sealing sheet of this invention is demonstrated.

  As shown in FIG. 1, the sealing sheet 1 is equipped with the sealing layer 2 which consists of an above-described sealing material, the base film 3, and the release film 4 in order in the thickness direction. Note that 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 sheet 1 and the base film 3 are separated from each other. It is a device that consists of a mold film 4 and is distributed industrially and can be used industrially.

  In order to prevent foreign matters from adhering to the sealing layer 2, it is preferable that the sealing layer 2 is protected by the base film 3 and the release film 4 when the sealing sheet 1 is stored. When the sealing sheet 1 is used, the base film 3 and the release film 4 are peeled off.

  The sealing layer 2 is a dried product of the above-described 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 above-described resin components have not reacted, 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, preferably 30 μm or less.

  The base film 3 is detachably attached to the back surface of the sealing layer 2 in order to support and protect the sealing layer 2 until the sealing sheet 1 is used for forming a sealing member (described later). Yes. 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 when the sealing sheet 1 is shipped, transported, and stored. The flexible film can be peeled off from the back surface of the sealing layer 2 so as to be bent in a substantially U shape.

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

  Examples of the material of the base film 3 include resin materials such as polyester (for example, polyethylene terephthalate (PET)) and polyolefin (for example, polyethylene, polypropylene, etc.), and preferably polyethylene terephthalate.

  Among the base films 3, a film having a moisture barrier property or a gas barrier property is preferable, and a film made of polyethylene terephthalate is more preferable. Although the thickness of the base film 3 is appropriately selected depending on the material of the film, it can be set to, for example, about 25 μm to 150 μm from the point of having followability to a sealing material such as a display element.

  The release film 4 is detachably attached to the surface of the sealing layer 2 in order to protect the sealing layer 2 until the sealing sheet 1 is used for forming a sealing member (described later). . 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 when the sealing sheet 1 is shipped, transported, and stored. The flexible film can be peeled off from the surface of the sealing layer 2 so as to be bent in a substantially U shape.

  The release film 4 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. Moreover, the sticking surface (back surface) of the release film 4 is peeled off as necessary. Examples of the material of the release film 4 include the same resin material as that of the base film 3. Although the thickness of the release film 4 is appropriately selected depending on the material of the film, it can be set to, for example, about 25 μm to 150 μm from the point of having followability to a sealing material such as a display element.

<Method for producing 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 sealing material described above 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 above-described resin component, curing agent, and additive in the above ratio. Moreover, in manufacture of the sealing sheet 1, a sealing material is preferably diluted with the organic solvent and the varnish of a sealing material is prepared.

  The organic solvent is not particularly limited as long as the resin component and the curing agent can be uniformly dispersed or dissolved. Examples of the organic solvent include aromatic hydrocarbons (eg, benzene, toluene, xylene, etc.), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ethers (eg, dibutyl ether, tetrahydrofuran, dioxane, ethylene). Glycol monoalkyl ether, ethylene glycol dialkyl ether, 1-methoxy-2-propanol, etc.), esters (eg, ethyl acetate, butyl acetate, etc.), nitrogen-containing compounds (eg, N-methylpyrrolidone, dimethylimidazolidinone, Dimethylformaldehyde, etc.). The organic solvent 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 into a flask and stirring, or kneading with a three roll.

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

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

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

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

  The sealing sheet 1 is manufactured by the above.

<Manufacture of image display device>
Such a sealing sheet 1 is suitably used for sealing (display element optical element) of an image display device. With reference to FIG. 2, an organic EL display with a touch sensor (hereinafter referred to as an organic EL display 10) as an embodiment of an image display device will be described.

  In the present embodiment, an organic EL display with a touch sensor is used 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 seal member 14, and a cover glass or 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 electrodes (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 atmospheric moisture from coming into contact with 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 arranged on the upper surface and side surfaces of the organic EL element 12 so as to surround the organic EL element 12. Examples of the material of the first inorganic barrier layer 17 include metal oxides (for example, aluminum oxide, silicon oxide, copper oxide, etc.), metal nitrides (for example, aluminum nitride, silicon nitride, etc.), and the like. The material of the first inorganic barrier layer 17 can be used alone or in combination of two or more. Among the materials of the first inorganic barrier layer 17, preferably a metal nitride, more preferably silicon nitride.

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

  The second inorganic barrier layer 18 is disposed on the upper surface and the side surface of the planarization layer 19 so as to surround the planarization layer 19. Examples of the material of the second inorganic barrier layer 18 include the same material as that of the first inorganic barrier layer 17.

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

  The sealing member 14 is a cured product of the sealing layer 2 (sealing material), and seals the organic EL element 12 covered with the barrier layer 16. The sealing member 14 is formed from the sealing layer 2 from which the base film 3 and the release film 4 are peeled off. Specifically, after the sealing layer 2 from which the base film 3 and the release film 4 have been peeled is attached to the substrate 13 so as to embed the organic EL element 12 covered with the barrier layer 16, the sealing layer A cover glass or a barrier film 15 is attached to the upper surface of 2, and then the sealing layer 2 is cured. Thereby, the seal 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, preferably 3.70 or less. In addition, a dielectric constant can be measured based on the method as described in the Example mentioned later.

  If the dielectric constant of the seal member 14 is equal to or higher than the lower limit, the degree of freedom in material selection can be improved. If the dielectric constant of the sealing member 14 is equal to or lower than the above upper limit, it is possible to suppress malfunctions 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. The moisture permeability can be measured according to the method described in the examples described later.

  When the moisture permeability of the seal member 14 is equal to or less than the above upper limit, it is possible to suppress deterioration of the optical element sealed by the seal member 14.

  The cover glass or barrier film 15 is disposed on the upper surface of the seal member 14. Although not shown, the cover glass or the barrier film 15 includes a glass plate and electrodes that are provided on the lower surface of the glass plate and constitute a sensor of an organic EL display with a touch sensor.

  Such an organic EL display 10 has 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 disposed on the organic EL element 12. Has an on-cell structure.

<Effect>
However, the sealing member of the liquid crystal display is provided in a frame shape so as to surround the periphery of the liquid crystal disposed between the base material and the glass plate, for example. On the other hand, as shown in FIG. 2, the sealing member of the organic EL display is provided so that the organic EL element is embedded therein. Therefore, the seal member of the organic EL display has a larger influence on the dielectric constant than the seal member of the liquid crystal display, and it is desired to reduce the dielectric constant.

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

  The inventors of the present invention have studied the composition of the resin component in various ways, and the resin component of the encapsulant contains a bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin, so that the dielectric constant can be reduced in the sealing member. However, the present inventors have found the knowledge that can ensure high transparency and completed the present invention.

  In the sealing material described above, since the resin component contains the bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin, the dielectric constant can be reduced to the range required for the image display device (particularly, the organic EL display) in the seal member, High transparency required for a display device (in particular, an organic EL display) can be secured.

  Moreover, as shown in FIG. 1, the sealing sheet 1 has the sealing layer 2 which consists of a sealing material. Therefore, the handling property of the sealing material can be improved. Further, in the sealing member, high transparency can be ensured while the dielectric constant can be reduced.

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 bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin (bisphenol TMC skeleton-containing epoxy resin) and the biphenyl skeleton-containing epoxy resin described above. It is not limited to this.

  In the second embodiment, the resin component contains a copolymer of a bisphenol alkyl-substituted cyclohexane skeleton-containing monomer (for example, bisphenol TMC) and a biphenyl skeleton-containing epoxy monomer (for example, tetramethylbiphenyl diglycidyl ether). 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 skeleton), 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, a bisphenol TMC skeleton-biphenyl skeleton-containing epoxy resin.

  Such a copolymer particularly preferably has a molecular chain containing 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 type). 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% by mass or more, preferably 30% by mass or more, for example, 70% by mass or less, preferably Is 60% by mass or less, more preferably 50% by mass or less.

  In the second embodiment, the resin component preferably contains a hydrogenated bisphenol A skeleton-containing epoxy resin as described 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 by such 2nd Embodiment, there can exist an effect similar to above-described 1st Embodiment.

Further, the resin component is a bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin as the bisphenol alkyl-substituted cyclohexane skeleton-containing epoxy resin in the first embodiment (preferably a bisphenol TMC skeleton-containing epoxy resin represented by the above formula (2)), and A copolymer with the biphenyl skeleton-containing epoxy resin in the first embodiment (preferably, the biphenyl skeleton-containing epoxy resin represented by the above formula (3)) can also be contained.
<Modification>
In the modification, the same members and steps as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 1, the sealing sheet 1 includes a sealing layer 2, a base film 3, and a release film 4, but the image display device sealing sheet is not limited to this. The image display device sealing sheet may not include the base film 3 and / or the release film 4 as long as the sealing layer 2 is included. That is, the image display device sealing sheet may be composed of only the sealing layer 2, and may include the sealing layer 2 and any one of the base film 3 and the release film 4.

  As shown in FIG. 2, the organic EL display 10 includes the barrier layer 16, but is not limited thereto. The organic EL display 10 may not include the barrier layer 16.

  The organic EL display 10 has 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 is disposed on the organic EL element 12. Although it has an on-cell structure, it is not limited to this.

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

  The sensor unit 25 is disposed on the seal member 14. The sensor unit 25 includes electrodes that constitute a sensor of an organic EL display with a touch sensor. In the organic EL display 20, the substrate 13 does not include an electrode.

  Also about each above-described modification, there exists an effect similar to above-described embodiment. The above-described embodiments and modifications can be combined as appropriate.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to them. Specific numerical values such as blending ratio (content ratio), physical property values, and parameters used in the following description are described in the above-mentioned “Mode for Carrying Out the Invention”, and the corresponding blending ratio (content ratio) ), Physical property values, parameters, etc. may be replaced with the upper limit values (numerical values defined as “less than” or “less than”) or lower limit values (numbers defined as “greater than” or “exceeded”). it can. “Part” and “%” are based on mass unless otherwise specified.

Synthesis example 1
In a flask equipped with a stirrer, thermometer, nitrogen blowing tube and cooling tube, 100 parts by mass of bisphenol TMC and 140 parts by mass of bisphenol TMC diglycidyl ether (ratio of the number of moles of epoxy groups / number of moles of phenolic hydroxyl groups = 1. 03) and 15 parts by mass of cyclohexanone as a reaction solvent were added, and the temperature was raised to 100 ° C. in a nitrogen atmosphere. Next, 0.1 parts by mass of methyltriphenylphosphonium bromide (TMP) as a catalyst was further charged into 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 allowed to react for 12 hours. The reaction temperature was 140 to 145 ° C. when the non-volatile content was 80% by mass or more, and thereafter the reflux temperature. 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 blowing tube and cooling tube, 100 parts by mass of bisphenol TMC and 118 parts by mass of tetramethylbiphenyldiglycidyl ether (ratio of moles of epoxy groups / moles of phenolic hydroxyl groups = 1) 0.03) and 15 parts by mass of cyclohexanone as a reaction solvent were added, and the temperature was raised to 100 ° C. in a nitrogen atmosphere. Next, 0.1 parts by mass of TMP as a catalyst was further charged into the flask, and then 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 allowed to react for 12 hours. The reaction temperature was 140 to 145 ° C. when the non-volatile content was 80% or more, and thereafter the reflux temperature. 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
Bisphenol TMC skeleton-containing epoxy resin obtained in each synthesis example shown in Table 1 and hydrogenated bisphenol A skeleton-containing epoxy resin (trade name: YX8000, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 352, epoxy equivalent: 205 g / eq .) And a biphenyl skeleton-containing epoxy resin (trade name: YX6954BH30, manufactured by Mitsubishi Chemical Corporation, in the above formula (3), R ² is a hydrogen atom and a methyl group, weight average molecular weight: 39,000, epoxy equivalent: 10,000 to 16,000 g / eq.) And a thermal cationic curing agent (trade name: CXC-1612, manufactured by King Industries) in the formulation shown in Table 1 (in terms of solid content) to prepare a sealing material did.

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 (trade name: CPI-210S, manufactured by San Apro).

Comparative Example 1
Bisphenol type phenoxy resin (trade name: jER4275, manufactured by Mitsubishi Chemical Corporation, containing bisphenol A skeleton and bisphenol F skeleton, epoxy equivalent: 8,400-9,200 g / eq.) And cycloalkene oxide type epoxy resin (trade name) : Celoxide 2021P, 3,4-epoxycyclohexylmethyl (3,4-epoxy) cyclohexanecarboxylate, molecular weight: 252.3, epoxy equivalent: 128-145 g / eq., And solid epoxy resin (trade name: jER4005P, Mitsubishi) Chemical company, epoxy equivalent: 1070 g / eq.) And thermal cationic curing agent (trade name: CXC-1612, manufactured by King Industries) are mixed in the formulation shown in Table 1 (in terms of solid content), A sealing material was prepared.

Comparative Example 2
Bisphenol-type phenoxy resin is a biphenyl skeleton-containing epoxy resin (trade name: YX6954BH30, manufactured by Mitsubishi Chemical Corporation, R ² is a hydrogen atom and a methyl group in the above formula (3), weight average molecular weight: 39,000, epoxy equivalent: 10, 000 to 16,000 g / eq.) A sealing material was prepared in the same manner as in Comparative Example 1 except that it was changed.

Comparative Example 3
Bisphenol type phenoxy resin (trade name: jER4275, manufactured by Mitsubishi Chemical Corporation, containing bisphenol A skeleton and bisphenol F skeleton, epoxy equivalent: 8,400-9,200 g / eq.), And hydrogenated bisphenol A skeleton-containing epoxy resin ( Product name: YX8000, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 352, epoxy equivalent: 205 g / eq.) And thermal cation initiator (trade name: CXC-1612, manufactured by King Industries) are shown in Table 1. It mixed by prescription (solid content conversion), and prepared the sealing material.

<Evaluation>
-Dielectric constant The sealing material of each Example and each comparative example is PET film (PET film (trade name: Purex A53, manufactured by Teijin DuPont Films Co., Ltd., thickness: 38 μm, base) After coating on the film), it was dried at 90 ° C. for 3 minutes in a nitrogen purge oven to form a sealing layer having a thickness of 15 μm.

  Next, a PET film (molded PET film (trade name: Purex A31, manufactured by Teijin DuPont Films, Inc., thickness: 38 μm, release film)) was bonded to the sealing layer at 80 ° C. by a thermal laminator. .

  By the above, the sealing sheet provided with a base film, a sealing layer, and a release film was prepared. By repeating this, two sealing sheets were prepared for each of Examples and Comparative Examples. And in two sealing sheets corresponding to the same Example or Comparative Example, after peeling the release film from the sealing layer, the two sealing layers were bonded together in the thickness direction, and their thickness was 30 μm. It was.

  Next, the two sealing layers bonded together are peeled from the base film on one side and cured at 100 ° C. for 1 hour, and then the base film on the other side is peeled off from the cured sealing layer for measurement. A sample was obtained. The dielectric constant at 100 kHz of the obtained sample was measured by an automatic equilibrium bridge method using an LCR meter HP4284A (manufactured by Agilent Technologies).

The dielectric constant was evaluated according to the following criteria. The results are shown in Table 1.
○: Less than 3.80 ×: 3.80 or more.

-Moisture permeability The sealing sheet of each Example and each comparative example was prepared like evaluation of said dielectric constant. And after peeling a release film from the sealing layer, the sealing layer was hardened at 100 degreeC for 1 hour. Next, the base film was peeled from the cured sealing layer to obtain a measurement sample. The moisture permeability (moisture permeability) of the obtained sample was measured under conditions of 60 ° C. and 90% RH in accordance with JIS Z0208. Then, it converted into the value in case the thickness of a sample is 100 micrometers from the film thickness of the sample used for the measurement.

The moisture permeability was evaluated according to the following criteria. The results are shown in Table 1.
○: Less than 45 g / m ² · 24 h Δ: 45 g / m ² · 24 h or more.

1 Sealing sheet 2 Sealing layer

Claims (3)

Containing a resin component and a curing agent,
The said resin component contains the bisphenol alkyl substituted cyclohexane frame containing epoxy resin, The image display apparatus sealing material characterized by the above-mentioned.   The image display device sealing material according to claim 1, wherein the resin component further contains a hydrogenated bisphenol A skeleton-containing epoxy resin.   The image display device sealing material according to claim 1, wherein 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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