阅读说明：本技术 图像显示装置密封材料及图像显示装置密封片 (Image display device sealing material and image display device sealing sheet ) 是由 富田裕介 高木正利 山本祐五 于 2018-06-19 设计创作，主要内容包括：图像显示装置密封材料含有树脂成分和固化剂,上述树脂成分含有：重均分子量为200以上100,000以下的含有联苯骨架的环氧树脂；重均分子量为180以上790以下的含有脂环骨架的环氧树脂；以及重均分子量为750以上4000以下的苯乙烯系低聚物。(The image display device sealing material contains a resin component and a curing agent, wherein the resin component contains: an epoxy resin having a biphenyl skeleton and a weight average molecular weight of 200 to 100,000; an epoxy resin having a weight average molecular weight of 180 to 790 inclusive and containing an alicyclic skeleton; and a styrene oligomer having a weight average molecular weight of 750 to 4000.)

1. An image display device sealing material comprising a resin component and a curing agent,

the resin component contains:

an epoxy resin having a biphenyl skeleton and a weight average molecular weight of 200 to 100,000;

an epoxy resin having a weight average molecular weight of 180 to 790 inclusive and containing an alicyclic skeleton; and

a styrene oligomer having a weight average molecular weight of 750 to 4000.

2. The sealing material for an image display device according to claim 1, wherein a content ratio of the styrene-based oligomer in the resin component is 5 to 25 mass%.

3. The image display device sealing material according to claim 1, wherein the styrene-based oligomer comprises a homopolymer of a monomer having a styrene skeleton.

4. The image display device sealing material according to claim 1, wherein the resin component further contains an aliphatic hydrocarbon resin.

5. The sealing material for an image display device according to claim 4, wherein the aliphatic hydrocarbon resin is contained in a proportion of 0.30 to 4.0 relative to the styrene-based oligomer.

6. The image display device sealing material according to claim 4, wherein in the resin component,

the content ratio of the aliphatic hydrocarbon resin is 20% by mass or less, and,

the total content of the styrene oligomer and the aliphatic hydrocarbon resin is 30% by mass or less.

7. An image display device-sealing sheet comprising the image display device-sealing material according to claim 1.

8. The image display device sealing sheet according to claim 7, wherein the image display device is an organic EL display.

Technical Field

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

Background

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 by a sealing member in order to suppress deterioration of the optical element due to moisture or the like in the atmosphere.

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

It is proposed, for example, that the polymer has a weight average molecular weight of 3X 10³～1×10⁴The bisphenol epoxy resin of (1), a phenol epoxy resin having a weight average molecular weight of 200 to 800, a curing accelerator, and a silane coupling agent (see, for example, patent document 1).

Disclosure of Invention

Problems to be solved by the invention

However, in the sealing member formed of the sealing composition described in patent document 1, for example, if the sealing member is used for a touch panel of an organic EL display or the like, since the dielectric constant is high, malfunction of the touch panel may occur due to noise caused by the sealing member. In such applications, the sealing member needs to have transparency.

The invention provides an image display device sealing material and an image display device sealing sheet, wherein the sealing member has a relatively low dielectric constant and can ensure transparency.

Means for solving the problems

The present invention [1] includes an image display device sealing material comprising a resin component and a curing agent, wherein the resin component comprises: an epoxy resin having a biphenyl skeleton and a weight average molecular weight of 200 to 100,000; an epoxy resin having a weight average molecular weight of 180 to 790 inclusive and containing an alicyclic skeleton; and a styrene oligomer having a weight average molecular weight of 750 to 4000.

The invention [2] comprises the image display device sealing material according to [1], wherein the styrene oligomer is contained in the resin component in a proportion of 5 to 25 mass%.

The invention [3] comprises the image display device sealing material according to [1] or [2], wherein the styrene-based oligomer comprises a homopolymer of a monomer having a styrene skeleton.

The invention [4] includes the image display device sealing material according to any one of the above [1] to [3], wherein the resin component further contains an aliphatic hydrocarbon resin.

The invention [5] comprises the image display device sealing material according to [4], wherein the aliphatic hydrocarbon resin is contained in a proportion of 0.30 to 4.0 relative to the styrene-based oligomer.

The invention [6] comprises the image display device sealing material according to [4] or [5], wherein the resin component contains the aliphatic hydrocarbon resin in a content ratio of 20% by mass or less, and a total content ratio of the styrene-based oligomer and the aliphatic hydrocarbon resin is 30% by mass or less.

The invention [7] includes an image display device sealing sheet having a sealing layer formed of the image display device sealing material according to any one of the above [1] to [6 ].

The invention [8] comprises the sealing sheet for an image display device according to [7], wherein the image display device is an organic EL display.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the image display device sealing material and the image display device sealing sheet of the present invention, since the resin component includes the epoxy resin containing a biphenyl skeleton and the styrene-based oligomer, a sealing member having a relatively low dielectric constant and ensuring transparency can be formed.

Drawings

Fig. 1 is a side sectional view of a seal sheet as an embodiment of the seal sheet for an image display device of the present invention.

Fig. 2 is a side sectional view of an organic EL display with a touch sensor as an embodiment (a form having an embedded structure or a surface-embedded structure) of an image display device including a sealing member formed of the sealing layer shown in fig. 1.

Fig. 3A is an explanatory view for explaining an embodiment (a form in which a sealing layer on a base film is attached to a substrate) of the method for manufacturing the organic EL display with a touch sensor shown in fig. 2, and shows a step of preparing an element mounting unit. Fig. 3B shows a step of attaching the sealing layer to the substrate so that the organic EL element is embedded in the sealing layer after fig. 3A. Fig. 3C shows a step of peeling the release film from the sealing layer and attaching the cover glass to the sealing layer after fig. 3B.

Fig. 4 is an explanatory view for explaining another embodiment (a form in which a sealing layer on a cover glass or a barrier film is attached to a substrate) of the method for manufacturing an organic EL display with a touch sensor.

Fig. 5 is a side sectional view of an organic EL display with a touch sensor according to another embodiment (a form having an external fitting structure) of the image display device.

Detailed Description

Sealing Material for image display device

The 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 provided in an image display device described later, and is a curable resin composition for forming a sealing member described later by curing. The sealing material contains a resin component and a curing agent.

(1) Resin component

The resin component contains a weight average molecular weight (M)_w) An epoxy resin containing a biphenyl skeleton of 200 to 100,000, and a weight average molecular weight (M)_w) An alicyclic skeleton-containing epoxy resin having a weight average molecular weight (M) of 180 to 790 inclusive_w) A styrene oligomer of 750 to 4000 inclusive.

(1-1) epoxy resin having Biphenyl skeleton

The epoxy resin containing a biphenyl skeleton is a high molecular weight (M) resin having a biphenyl skeleton and an epoxy group_w: 200 to 100,000). The epoxy resin having a biphenyl skeleton is solid at room temperature. The term "solid at room temperature" means a solid state having no fluidity at room temperature (23 ℃), and the term "liquid at room temperature" means a liquid state having fluidity at room temperature (23 ℃) (the same applies hereinafter).

Weight average molecular weight (M) of epoxy resin having biphenyl skeleton_w) Is 200 or more, preferably 250 or more, more preferably 800 or more, further preferably 900 or more, and is 100,000 or less, preferably 90,000 or less. Weight average molecular weight (M)_w) Can be determined by Gel Permeation Chromatography (GPC) using polystyrene as a standard substance (the same applies below).

The epoxy equivalent of the epoxy resin having a biphenyl skeleton is, for example, 100 g/eq.or more, preferably 150 g/eq.or more, for example, 20,000 g/eq.or less, preferably 16,000 g/eq.or less.

Such an epoxy resin having a biphenyl skeleton has, for example, a plurality of biphenyl skeletons and a plurality of epoxy groups (a polyfunctional (including 2-functional) type epoxy resin), and preferably has a molecular chain having a plurality of biphenyl skeletons and epoxy groups bonded to both ends of the molecular chain (a 2-functional type epoxy resin).

Examples of the epoxy resin having a biphenyl skeleton include biphenyl type phenoxy resins represented by the following formula (1).

Formula (1)

[ solution 1]

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

The epoxy resin having a biphenyl skeleton preferably contains a biphenyl type phenoxy resin having the structural units I to III represented by the above formula (1), and more preferably a biphenyl type phenoxy resin having the structural units I to III represented by the above formula (1) is used alone.

When the biphenyl skeleton-containing epoxy resin contains a biphenyl type phenoxy resin having the structural units I to III represented by the above formula (1), the moisture permeability of the sealing member (described later) can be reduced.

The biphenyl type phenoxy resin having the structural units I to III represented by the above formula (1) is a copolymer of a dihydroxybiphenyl derivative and epichlorohydrin, and has a molecular chain containing a plurality of biphenyl skeletons and glycidyl ether units bonded to both ends of the molecular chain.

Examples of the alkyl group represented by R in the formula (1) include a straight-chain alkyl group having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, pentyl, and hexyl), a branched-chain alkyl group having 3 to 6 carbon atoms (e.g., isopropyl, isobutyl, and tert-butyl), and the like.

In R in the above formula (1), preferred examples include a hydrogen atom and a methyl group. In addition, a plurality of R in formula (1) may be the same or different from each other.

Examples of the biphenyl type phenoxy resin represented by the above formula (1) include an epoxy resin formed from a reactant (copolymer) of epichlorohydrin and 4,4 '-biphenol, and an epoxy resin formed from a reactant (copolymer) of epichlorohydrin and 4, 4' - (3,3 '-5, 5' -tetramethyl) biphenol. Such biphenyl type phenoxy resins can be used alone or in combination of 2 or more.

The biphenyl type phenoxy resin represented by the above formula (1) may contain other structural units in addition to the structural units I to III. Examples of the other structural units include a polyol unit derived from a polyol having a valence of 2 or more (e.g., ethylene glycol, benzene glycol, etc.), a bisphenol unit derived from a bisphenol (e.g., 4,4 '- (1-phenylethylidene) bisphenol, 4, 4' - (1-phenylpropylidene) bisphenol, etc.), and the like.

Among other constituent units, a bisphenol unit is preferable, and a unit derived from 4, 4' - (1-phenylethylidene) bisphenol is more preferable.

Among such biphenyl type phenoxy resins, preferred is an epoxy resin comprising a reaction product (copolymer) of 4,4 ' - (3,3 ' -5,5 ' -tetramethyl) diphenol and epichlorohydrin with bisphenol.

The weight average molecular weight (M) of the biphenyl type phenoxy resin represented by the above formula (1)_w) For example, 1,000 or more, preferably 2,000 or more, for example, 100,000 or less, preferably 90,000 or less. The biphenyl type phenoxy resin represented by the above formula (1) has an epoxy equivalent of, for example, 500 g/eq.or more, preferably 1,000 g/eq.or more, for example, 20,000 g/eq.or less, preferably 16,000 g/eq.or less.

As the biphenyl type phenoxy resin represented by the above formula (1), commercially available ones can be used. Examples of commercially available biphenyl-type phenoxy resins represented by the above formula (1) include YX6954BH30 (manufactured by Mitsubishi chemical corporation, epoxy equivalent: 10,000 to 16,000 g/eq.).

Examples of the epoxy resin having a biphenyl skeleton include, in addition to the biphenyl-type phenoxy resin described above, epoxy resins having a biphenyl skeleton which have the structural units I and III represented by the above formula (1) and do not have the structural unit II (that is, epoxy resins in which n is 0).

Examples of the epoxy resin having a biphenyl skeleton, which has the structural units I and III represented by the above formula (1) but does not have the structural unit II, include 4,4 '-bis (2, 3-epoxypropoxy) biphenyl, 4, 4' -bis (2, 3-epoxypropoxy) -3,3 '-5, 5' -tetramethylbiphenyl, and the like.

The epoxy resin having a biphenyl skeleton (n ═ 0) which has the structural units I and III shown in the above formula (1) and does not have the structural unit II may further contain the other structural units described above as long as it has the structural units I and II as main components.

The weight average molecular weight (M) of the biphenyl skeleton-containing epoxy resin (n ═ 0) having the structural units I and III represented by the above formula (1) and not having the structural unit II_w) Is 200 or more, preferably 250 or more, for example 2000 or less, preferably 1000 or less, more preferably less than 1000, and particularly preferably 800 or less. The epoxy equivalent of the epoxy resin containing a biphenyl skeleton (n ═ 0) having the structural units I and III represented by the formula (1) and not having the structural unit II is, for example, 100 g/eq.or more, preferably 125 g/eq.or more, for example, 1000 g/eq.or less, preferably 500 g/eq.or less, more preferably less than 500 g/eq.and particularly preferably 300 g/eq.or less.

A commercially available epoxy resin having a biphenyl skeleton (n ═ 0) which has the structural units I and III represented by the above formula (1) and does not have the structural unit II can also be used. Examples of commercially available epoxy resins (n 0) having a biphenyl skeleton, which have structural units I and III represented by formula (1) but do not have structural unit II, include YX4000 (manufactured by mitsubishi chemical corporation, epoxy equivalent 180 to 192g/eq.), YX4000H (manufactured by mitsubishi chemical corporation, epoxy equivalent 187 to 197g/eq.), YL6121H (manufactured by mitsubishi chemical corporation, epoxy equivalent 170 to 180g/eq.), and the like.

In the resin component, the content of the epoxy resin having a biphenyl skeleton is, for example, 5% by mass or more, preferably 10% by mass or more, for example, 50% by mass or less, preferably 40% by mass or less.

(1-2) epoxy resin having alicyclic skeleton

The epoxy resin containing an alicyclic skeleton is a low molecular weight (M) resin having at least an epoxy group and an aliphatic ring (alicyclic skeleton)_w: 180 to 790 inclusive). The epoxy resin having an alicyclic skeleton is liquid at normal temperature. The epoxy resin having an alicyclic skeleton does not have a biphenyl skeleton.

The weight average molecular weight of the alicyclic skeleton-containing epoxy resin is 180 or more and 790 or less, preferably 500 or less. The epoxy equivalent of the alicyclic skeleton-containing epoxy resin is, for example, 90 g/eq.or more, preferably 100 g/eq.or more, for example 190 g/eq.or less, preferably 200 g/eq.or less.

The epoxy resin having an alicyclic skeleton has, for example, a plurality of aliphatic rings and a plurality of epoxy groups (a polyfunctional (including 2-functional) epoxy resin).

Examples of the epoxy resin having an alicyclic skeleton include the following resins: an epoxy group-containing alicyclic skeleton epoxy resin (2-functional epoxy resin) having an epoxy group composed of adjacent 2 carbon atoms forming an aliphatic ring and 1 oxygen atom bonded to the 2 carbon atoms; an alicyclic skeleton epoxy resin (polyfunctional epoxy resin) containing a glycidyl ether, which has a plurality of glycidyl ether units bonded to an aliphatic ring. The epoxy resin having an alicyclic skeleton can be used alone or in combination.

Since the resin component contains the epoxy resin having an alicyclic skeleton, the haze value of the sealing member (described later) can be reduced as compared with the case where the resin component contains the epoxy resin having an aromatic ring skeleton, and the transparency of the sealing member (described later) can be improved.

Examples of the epoxy group-containing alicyclic epoxy resin include alicyclic epoxy compounds having an oxidized cycloolefin structure.

Examples of the alicyclic epoxy compound having an oxidized cycloolefin structure include an epoxy compound having an epoxycyclohexane structure represented by the following formula (2) (hereinafter, referred to as an ECH structure-containing epoxy compound), a modified product thereof, and the like.

Formula (2)

[ solution 2]

[ in the formula (2), X represents a single bond or a linking group (a 2-valent group having 1 or more atoms, and a substituent such as an alkyl group may be bonded to a carbon atom constituting a cyclohexane ring ]

The epoxy compound having an ECH structure represented by the above formula (2) has an epoxycyclohexane structure (epoxycyclohexyl group) at both ends of the molecule, and 2 epoxycyclohexyl groups are bonded directly by a single bond or bonded via a linking group. In addition, the epoxycyclohexyl group is a functional group containing a cyclohexane ring and an epoxy group consisting of adjacent 2 carbon atoms forming the cyclohexane ring and 1 oxygen atom bonded to these 2 carbon atoms.

In the above formula (2), when X is a single bond, the carbon atom forming the cyclohexane ring of the epoxycyclohexyl group at one terminal is directly bonded to the carbon atom forming the cyclohexane ring of the epoxycyclohexyl group at the other terminal.

Examples of the linking group represented by X in the formula (2) include a 2-valent hydrocarbon group, a carbonyl group, an ether group, a thioether group, an ester group, a carbonate group, an amide group, and a group obtained by linking these groups.

Examples of the 2-valent hydrocarbon group include a linear or branched alkylene group having 1 to 18 carbon atoms (e.g., methylene, methylmethylene, dimethylmethylene, ethylene, propylene, trimethylene, etc.), a cycloalkylene group (e.g., 1, 2-cyclopentylene, 1, 3-cyclopentylene, 1, 2-cyclohexylene, 1, 3-cyclohexylene, 1, 4-cyclohexylene, etc.), a cycloalkylidene group (e.g., cyclopentylidene, cyclohexylidene, etc.), and the like.

Among the linking groups represented by X in the above formula (2), from the viewpoint of adhesiveness of the sealing member (described later), preferred are linking groups containing an oxygen atom, more preferred are carbonyl groups, ether groups, ester groups, and carbonate groups, and particularly preferred are ester groups.

Examples of the alkyl group which can be bonded to a carbon atom constituting the cyclohexane ring include, for example, the same alkyl groups as those of R of the above formula (1). Further, a hydrogen atom is preferably bonded to a carbon atom constituting the cyclohexane ring without a substituent (unsubstituted).

Examples of the epoxy compound having an ECH structure represented by the formula (2) include (3,3 ', 4, 4' -diepoxy) bicyclohexane, bis (3, 4-epoxycyclohexylmethyl) ether, 1, 2-bis (3, 4-epoxycyclohexan-1-yl) ethane, 1, 2-epoxy-1, 2-bis (3, 4-epoxycyclohexan-1-yl) ethane, 2-bis (3, 4-epoxycyclohexan-1-yl) propane, 3, 4-epoxycyclohexylmethyl (3, 4-epoxy) cyclohexanecarboxylate, and e-caprolactone-modified 3 ', 4' -epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylate.

The epoxy compound having an ECH structure represented by the above formula (2) can be commercially available. Commercially available products of the epoxy compound having an ECH structure represented by the above formula (2) include, for example, celloxin 8000, celloxin 2021P (epoxy equivalent 128 to 145g/eq.), and celloxin 2081 (both trade names, manufactured by xylonite corporation).

Examples of the glycidyl ether-containing alicyclic skeleton epoxy resin include dicyclopentadiene type epoxy resins represented by the following formula (3) (hereinafter, referred to as DCPD type epoxy resins).

Formula (3)

[ solution 3]

[ in the formula (3), a substituent such as an alkyl group may be bonded to a carbon atom constituting an aliphatic ring derived from dicyclopentadiene. ]

The DCPD-type epoxy resin represented by the above formula (3) has an alicyclic ring derived from dicyclopentadiene and 2 glycidyl ether units bonded to the alicyclic ring.

Examples of the alkyl group which can be bonded to a carbon atom constituting an alicyclic ring derived from dicyclopentadiene include, for example, the same alkyl groups as those mentioned for R in the above formula (1). Further, a hydrogen atom is bonded to a carbon atom constituting an aliphatic ring derived from dicyclopentadiene, and a substituent is not bonded (unsubstituted).

Commercially available products of the DCPD-type epoxy resin represented by the above formula (3) can also be used. Examples of commercially available products of the DCPD type epoxy resin represented by the above formula (3) include EP-4088S (manufactured by ADEKA Inc., having an epoxy equivalent of 170 g/eq.).

Such an alicyclic skeleton-containing epoxy resin can be used alone or in combination of 2 or more, but is preferably used alone. That is, the epoxy resin having an alicyclic skeleton is preferably one of the epoxy compound having an ECH structure represented by the formula (2) and the DCPD-type epoxy resin represented by the formula (3) used alone.

When the epoxy compound having an ECH structure represented by the above formula (2) is used alone as the epoxy resin having an alicyclic skeleton, the curing speed of the sealing material can be improved as compared with the case where the DCPD type epoxy resin represented by the above formula (3) is used alone as the epoxy resin having an alicyclic skeleton.

In the resin component, the content of the epoxy resin having an alicyclic skeleton is, for example, 10% by mass or more, preferably 20% by mass or more, for example, 50% by mass or less, preferably 40% by mass or less.

When the content ratio of the epoxy resin having an alicyclic skeleton is within the above range, the haze value of the sealing member (described later) can be reduced.

(1-3) styrenic oligomer

The styrene-based oligomer is a polymer in which vinyl groups of a plurality of styrene skeletons are bonded to each other, and has a plurality of styrene units derived from a plurality of styrene skeletons. The styrene-based oligomer is in a solid state at normal temperature.

The styrene-based oligomer does not contain the weight-average molecular weight (M) as shown in comparative example 4 described later_w) A high molecular weight styrene-butadiene-styrene block copolymer (SBS rubber) exceeding 10,000.

Weight average molecular weight (M) of styrenic oligomer_w) 750 or more, preferably 900 or more, 4000 or less, preferably 3800 or less. Number average molecular weight (M) of styrenic oligomer_n) For example, 500 or more, preferably 600 or more, more preferably 700 or more, for example, 2500 or less, preferably 2000 or less, more preferably 1500 or less.

Further, weight average molecular weight/number average molecular weight (M)_w/M_n) For example, 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more, and for example, 2.5 or less, preferably 2.0 or less, more preferably 1.9 or less.

Examples of the styrenic oligomer include homopolymers of monomers having a styrene skeleton, and copolymers of monomers having a styrene skeleton and other polymerizable monomers. Such styrenic oligomers can be used alone or in combination of 2 or more.

Examples of the styrene skeleton-containing monomer include styrene, α -methylstyrene, vinyltoluene, isopropenyltoluene and the like, and isopropenyltoluene is preferably used. The styrene skeleton-containing monomers may be used alone or in combination of 2 or more.

The other polymerizable monomer is a monomer which can be polymerized with a monomer having a styrene skeleton and has, for example, an ethylenically unsaturated double bond. Examples of the other polymerizable monomer include unsaturated aliphatic monomers having 2 to 10 carbon atoms (e.g., ethylene, propylene, butene, isobutylene, butadiene, pentene, pentadiene, isoprene, hexadiene, and methylbutene), unsaturated alicyclic monomers having 5 to 20 carbon atoms (e.g., cyclopentadiene and dicyclopentadiene), α, β -unsaturated carboxylic acids (e.g., acrylic acid and methacrylic acid), (meth) acrylic acid esters, and C-containing monomers obtainable by purification, decomposition, or the like of petroleum₅And (4) fractionation and the like. C₅The fraction is a fraction having a boiling point range of usually-15 ℃ to +45 ℃ at normal pressure, and contains 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-pentene, isoprene, 1, 3-pentadiene, cyclopentadiene and the like. The other polymerizable monomers may be used alone or in combination of 2 or more.

In the copolymer of the styrene skeleton-containing monomer and the other polymerizable monomer, the content ratio of the structural unit derived from the styrene skeleton-containing monomer is, for example, 50% by mass or more, preferably 80% by mass or more, for example, 99% by mass or less, preferably 95% by mass or less.

Among the styrene-based oligomers, a homopolymer of a monomer having a styrene skeleton is preferably used. That is, the styrenic oligomer preferably comprises a homopolymer of a monomer having a styrene skeleton, and more preferably a homopolymer of a monomer having a styrene skeleton alone.

In the case where the styrenic oligomer includes a homopolymer of a monomer having a styrene skeleton (particularly, in the case where a homopolymer of a monomer having a styrene skeleton is used alone), a decrease in moisture permeability of a sealing member (described later) can be achieved.

The content of the styrene-based oligomer in the resin component is, for example, 1 mass% or more, preferably 5 mass% or more, for example, 40 mass% or less, preferably 25 mass% or less, more preferably 20 mass% or less, and particularly preferably 18 mass% or less.

When the content ratio of the styrene-based oligomer is within the above range, the dielectric constant of the sealing member (described later) can be reduced, and the haze value of the sealing member (described later) can be reduced.

(1-4) an optional resin component such as an aliphatic hydrocarbon resin

The resin component preferably contains an aliphatic hydrocarbon resin as an optional component. When the resin component contains an aliphatic hydrocarbon resin, the haze value of the sealing member (described later) can be reliably reduced, and the transparency of the sealing member (described later) can be reliably improved.

The aliphatic hydrocarbon resin is C obtained by decomposing naphtha₅Petroleum hydrocarbon resin using dicyclopentadiene extracted from the fraction as a main raw material. The aliphatic hydrocarbon resin has an aliphatic ring derived from dicyclopentadiene and has no epoxy group. The aliphatic hydrocarbon resin is a solid in the form of a flake at ordinary temperature.

The weight average molecular weight (Mw) of the aliphatic hydrocarbon resin is, for example, 400 or more, preferably 500 or more, for example, 1500 or less, preferably 1000 or less.

The softening point of the aliphatic hydrocarbon resin is, for example, 80 ℃ to 120 ℃. Here, the softening point can be measured by the method described in JIS K2207.

The aliphatic hydrocarbon resin has a bromine number of, for example, 70g/100g to 90g/100 g. Here, the softening point can be measured by the method described in JIS K2543.

Examples of the aliphatic hydrocarbon resin include homopolymers of dicyclopentadiene (hereinafter, referred to as an unmodified alicyclic resin), ester-modified alicyclic resins obtained by introducing an ester group into an unmodified alicyclic resin, and the like. Such aliphatic hydrocarbon resins may be used alone or in combination of 2 or more.

Among the aliphatic hydrocarbon resins, from the viewpoint of compatibility, preferred is an ester-modified alicyclic resin. That is, the aliphatic hydrocarbon resin preferably contains an aliphatic hydrocarbon resin, more preferably contains an ester-modified alicyclic resin, and particularly preferably contains an ester-modified alicyclic resin alone.

The saponification value of the ester-modified alicyclic resin is, for example, 100mgKOH/g or more and 200mgKOH/g or less. The softening point can be measured by the method described in JIS K0070.

Commercially available products of such ester-modified alicyclic resins can also be used. Examples of commercially available products of ester-modified alicyclic resins include Quintone1500 (manufactured by nippon corporation) and Quintone1525L (manufactured by nippon corporation).

The content of the aliphatic hydrocarbon resin in the resin component is, for example, 1 mass% or more, preferably 5 mass% or more, for example, 30 mass% or less, preferably 20 mass% or less.

In the resin component, the total content of the styrene-based oligomer and the aliphatic hydrocarbon resin is, for example, 2 mass% or more, preferably 10 mass% or more, for example, 40 mass% or less, preferably 30 mass% or less.

If the content ratio of the aliphatic hydrocarbon resin is not less than the lower limit and the total content ratio of the styrene-based oligomer and the aliphatic hydrocarbon resin is not less than the lower limit, the dielectric constant can be reliably reduced in the sealing member (described later), and high transparency can be stably ensured. If the content ratio of the aliphatic hydrocarbon resin is not more than the upper limit and the content ratio of the sum of the styrene-based oligomer and the aliphatic hydrocarbon resin is not more than the upper limit, the moldability of the sealing material can be appropriately adjusted, and the sealing material can be stably molded into a sheet shape.

The content ratio (mass ratio) of the aliphatic hydrocarbon resin relative to the styrene-based oligomer is, for example, 0.2 or more, preferably 0.30 or more, for example, 5.0 or less, preferably 4.0 or less.

If the content ratio of the aliphatic hydrocarbon resin relative to the styrene-based oligomer is not less than the lower limit, the haze value of the sealing member (described later) can be reliably reduced, and the transparency of the sealing member (described later) can be reliably improved. If the content ratio of the aliphatic hydrocarbon resin relative to the styrene-based oligomer is not more than the upper limit, the dielectric constant can be more reliably reduced in the sealing member (described later), and high transparency can be more stably ensured.

The resin component may further contain, as an optional component, an epoxy resin having a bisphenol skeleton and a weight average molecular weight of 800 to 100,000.

The epoxy resin having a bisphenol skeleton has a plurality of bisphenol skeletons and a plurality of epoxy groups (polyfunctional (including 2-functional) type epoxy resin), and is solid at ordinary temperature. The epoxy resin having a bisphenol skeleton does not have a biphenyl skeleton and has a higher molecular weight than the above-mentioned epoxy resin having an alicyclic skeleton.

Specifically, the epoxy resin having a bisphenol skeleton has a weight average molecular weight (Mw) of 800 or more, preferably 900 or more, 100,000 or less, preferably 90,000 or less.

The epoxy equivalent of the epoxy resin having a bisphenol skeleton is, for example, 100 g/eq.or more, preferably 150 g/eq.or more, for example, 20,000 g/eq.or less, preferably 15,000 g/eq.or less.

The epoxy resin having a bisphenol skeleton is, for example, a copolymer of bisphenol and epichlorohydrin, and has a molecular chain including a plurality of bisphenol skeletons and glycidyl ether units bonded to both ends of the molecular chain (2-functional epoxy resin). Examples of the bisphenol include bisphenol a and bisphenol F, and bisphenol F is preferable.

The epoxy resin having a bisphenol skeleton is included in order to adjust the content ratio of the resin component for the purpose of moldability of a sealing member (described later). In the examples described later, when the content ratio of the other resin component is changed, the content ratio of the epoxy resin having a bisphenol skeleton is adjusted so that the total of the resin components becomes 100 parts by mass (that is, the content ratio of the epoxy resin having a bisphenol skeleton is 100 — the total of the content ratios of the other resin components).

Specifically, the content of the epoxy resin having a bisphenol skeleton in the resin component is, for example, 5% by mass or more, preferably 15% by mass or more, for example 40% by mass or less, preferably 30% by mass or less. When the content ratio of the epoxy resin having a bisphenol skeleton is within the above range, moldability of the sealing member (described later) is improved.

The resin component may contain other resin components than the specific resin components (the epoxy resin having a biphenyl skeleton, the epoxy resin having an alicyclic skeleton, the styrene-based oligomer, the aliphatic hydrocarbon resin, and the epoxy resin having a bisphenol skeleton) described above within a range not to impair the effects of the present invention.

Examples of the other resin component include other epoxy resins (for example, an epoxy resin having a bisphenol skeleton and a weight average molecular weight of less than 800), polyolefins (for example, polyethylene, polybutadiene, and the like), polychloroprene, polyamides, polyamideimides, polyurethanes, polyethers, polyesters, silicone resins, and the like. These other resin components can be used alone or in combination of 2 or more. The content of the other resin component in the resin component is, for example, 10% by mass or less, preferably 5% by mass or less.

(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 it can cure the sealing material. Examples of the curing agent include amine-based curing agents (e.g., diethylenetriamine, triethylenetetramine, tris (dimethylaminomethyl) phenol, etc.), imidazole-based curing agents (e.g., 2-methylimidazole, 2-ethyl-4-methylimidazole, etc.), acid anhydride-based curing agents (e.g., phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, etc.), and thermal cationic curing agents. Such curing agents can be used alone or in combination of 2 or more.

Among the curing agents, a thermal cationic curing agent is preferably used. That is, the curing agent preferably contains a thermal cationic curing agent, and the thermal cationic curing agent is preferably used alone. If the curing agent contains a thermal cationic curing agent, the curing speed of the sealing material can be improved.

The thermal cationic curing agent is a thermal acid generator that generates an acid by heating. The thermal cationic curing agent is not particularly limited as long as it is a compound that can initiate polymerization of the above-described (1-1) epoxy resin having a biphenyl skeleton and (1-2) epoxy resin having an alicyclic skeleton by generating cations by heating, and is preferably a compound that can initiate polymerization at a heat-resistant temperature of 120 ℃ or lower as a display element (for example, an organic EL element or the like). As the thermal cationic curing agent, a known cationic polymerization initiator can be used. As the thermal cationic polymerization initiator, for example, AsF₆ ^-、SbF₆ ^-、PF₆ ^-、BF₄ ^-、B(C₆F₅)₄ ^-、CF₃SO₃ ^-Etc. as counter anions, sulfonium salts,Salt, quaternary ammonium salt, diazoSalt and iodineSalts and the like.

Examples of the sulfonium salt include boron fluoride-based sulfonium salts (e.g., triphenylsulfonium boron tetrafluoride), arsenic fluoride-based sulfonium salts (e.g., triphenylsulfonium arsenic hexafluoride, tris (4-methoxyphenyl) sulfonium arsenic hexafluoride, diphenyl (4-phenylthiophenyl) sulfonium arsenic hexafluoride, etc.), antimony fluoride-based sulfonium salts (e.g., triphenylsulfonium antimony hexafluoride, etc.), phosphorus fluoride-based sulfonium salts (e.g., triphenylsulfonium phosphorus hexafluoride, etc.), etc.

AsThe salt includes, for example, antimony fluorideSalts (e.g., ethyltriphenylphosphonium)Antimony hexafluoride, tetrabutylAntimony hexafluoride, etc.), and the like.

Examples of the quaternary ammonium salt include antimony fluoride-based quaternary ammonium salts (e.g., antimony N, N-dimethyl-N-benzylanilinium hexafluoride, and N, N-dimethyl-N-benzylpyridine)Antimony hexafluoride, N-dimethyl-N- (4-methoxybenzyl) pyridineAntimony hexafluoride, N-diethyl-N- (4-methoxybenzyl) pyridineAntimony hexafluoride, antimony N, N-diethyl-N- (4-methoxybenzyl) tolueneammonium hexafluoride, antimony N, N-dimethyl-N- (4-methoxybenzyl) tolueneammonium hexafluoride, etc.), boron fluoride-based quaternary ammonium salts (e.g., boron N, N-diethyl-N-benzylanilinium tetrafluoride, etc.), organic acid-based quaternary ammonium salts (e.g., N, N-diethyl-N-benzylpyridine, etc.)Trifluoromethanesulfonic acid, etc.), and the like.

As iodineThe salt may be, for example, antimony fluoride-based iodineSalts (e.g. diphenyliodine)Antimony hexafluoride, etc.), fluorinePhosphorus iodideSalts (e.g. diphenyliodine)Phosphoric acid hexafluoride, etc.), boron fluoride-based iodineSalts (e.g. diphenyliodine)Boron tetrafluoride, etc.), and the like.

Such a thermal cationic curing agent can be used alone or in combination of 2 or more.

Among the thermal cationic curing agents, quaternary ammonium salts are preferable, and antimony fluoride quaternary ammonium salts are more preferable.

Commercially available products of such thermal cationic curing agents can also be used. As commercial products of the thermal cationic curing agent, there are mentioned, for example, CXC-1612, CXC-1733, CXC1821 (all King Industries Co., Ltd.), SAN-AID SI-60, SAN-AID SI-80, SAN-AID SI-B3, SAN-AID SI-B3A, SAN-AID SI-B4 (all Sanxin chemical Industries Co., Ltd.), TA-100(SAN-apro Co., Ltd.), and the like.

The content of the curing agent is, for example, 0.5 parts by mass or more, preferably 1 part by mass or more, for example, 10 parts by mass or less, and preferably 5 parts by mass or less, relative to 100 parts by mass of the resin component.

(3) Other additives

The sealing material may contain, as other additives, an organic solvent, a silane coupling agent, a leveling agent, and the like as required.

If the sealing material contains an organic solvent, the sealing material can be prepared as a varnish. The organic solvent is not particularly limited as long as the resin component and the curing agent are uniformly dispersed or dissolved. Examples of the organic solvent include aromatic hydrocarbons (e.g., benzene, toluene, xylene, etc.), ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), and the like) Ethers (e.g. dibutyl ether, tetrahydrofuran, dibutyl ether)Alkanes, ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, 1-methoxy-2-propanol, etc.), esters (e.g., ethyl acetate, butyl acetate, etc.), nitrogen-containing compounds (e.g., N-methylpyrrolidone, dimethylimidazolidinone, dimethylformaldehyde, etc.), and the like. Such organic solvents can be used alone or in combination of 2 or more.

Among the organic solvents, ketones are preferable, and methyl ethyl ketone is more preferable. When the organic solvent contains a ketone, the resin component (particularly, an epoxy resin having a biphenyl skeleton) can be uniformly dissolved.

The content of the organic solvent is, for example, 50 parts by mass or more, preferably 60 parts by mass or more, for example, 90 parts by mass or less, and preferably 80 parts by mass or less, relative to 100 parts by mass of the resin component.

When the sealing material contains a silane coupling agent, the adhesion of a sealing member (described later) to a substrate (described later) can be improved.

Examples of the silane coupling agent include epoxy group-containing silane coupling agents (e.g., γ -glycidoxypropyltrimethoxysilane, γ -glycidoxypropyltriethoxysilane, β - (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, etc.), amino group-containing silane coupling agents (e.g., N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyltriethoxysilane, 3-aminopropyltrimethoxysilane, etc.), methacryloyl group-containing silane coupling agents (e.g., γ -methacryloxypropylmethyldimethoxysilane, gamma-glycidoxypropyl-triethoxysilane, beta-epoxycyclohexyl) ethyltrimethoxysilane, etc.), methacryloyl group-containing silane coupling agents, Gamma-methacryloxypropyltrimethoxysilane, and the like). Such silane coupling agents can be used alone or in combination of 2 or more.

Among the silane coupling agents, preferred are those containing an epoxy group, and more preferred is gamma-glycidoxypropyltrimethoxysilane.

The content of the silane coupling agent is, for example, 0.05 parts by mass or more, preferably 0.1 parts by mass or more, for example, 30 parts by mass or less, preferably 5 parts by mass or less, relative to 100 parts by mass of the resin component.

If the sealing material contains a leveling agent, the surface of the sealing material can be smoothed when the sealing material is applied. The content of the leveling agent is, for example, 0.01 parts by mass or more, preferably 0.1 parts by mass or more, for example, 5.0 parts by mass or less, preferably 1.0 part by mass or less, relative to 100 parts by mass of the resin component.

The sealing material may further contain, as other additives, a filler, a polymerization initiation aid, an antioxidant, a wettability improver, a surfactant, a plasticizer, an ultraviolet absorber, an antiseptic, an antibacterial agent, and the like at an appropriate ratio as required.

Sealing sheet for image display device

The sealing material can be directly distributed as a single material and is an industrially available product, but is preferably distributed as a sealing sheet for an image display device from the viewpoint of operability.

A seal sheet 1 as an embodiment of the seal sheet for an image display device of the present invention will be described with reference to fig. 1.

As shown in fig. 1, the sealing sheet 1 includes: a sealing layer 2 formed of the above-described sealing material, a base film 3, and a release film 4. The sealing sheet 1 is a member for manufacturing an image display device, does not include a display element and a substrate on which the display element is mounted, and specifically, is a device which is composed of a sealing layer 2, a base film 3, and a release film 4, is distributed as a single member, and is industrially applicable.

In order to prevent foreign matter from adhering to the sealing layer 2 and the like, the sealing layer 2 is preferably 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.

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 front surface and a flat back surface.

In the sealing layer 2, the above epoxy components (the epoxy resin having a biphenyl skeleton, the epoxy resin having an alicyclic skeleton, and the epoxy resin having a bisphenol skeleton) are not reacted, and these epoxy components are contained in the sealing layer 2 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 peelably attached to the back surface of the sealing layer 2 to support and protect the sealing layer 2 during a period before the sealing sheet 1 is used to form a sealing member (described later). That is, the base film 3 is a flexible film, and 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, transportation, and storage of the sealing sheet 1, and can be peeled off from the back surface of the sealing layer 2 so as to be bent into a substantially U shape immediately before the use of the sealing sheet 1.

The base film 3 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. The attached surface (surface) of the base film 3 is subjected to a peeling treatment as necessary.

Examples of the material of the base film 3 include resin materials such as polyester (e.g., polyethylene terephthalate (PET)), polyolefin (e.g., 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. The thickness of the base film 3 is also appropriately selected depending on the material of the film, but may be, for example, about 25 μm to 150 μm in view of having a capability of following the 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 before the sealing sheet 1 is used for forming a sealing member (described later). That is, the release film 4 is a flexible film, and 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, and can be peeled off from the surface of the sealing layer 2 so as to be bent into a substantially U shape immediately before the sealing sheet 1 is used.

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. The sticking surface (back surface) of the release film 4 is subjected to a peeling treatment as necessary. Examples of the material of the release film 4 include the same resin materials as those of the base film 3. The thickness of the release film 4 is also appropriately selected depending on the material of the film, but may be, for example, about 25 μm to 150 μm in view of having a capability of following the material to be sealed such as a display device.

Method for manufacturing sealing sheet for image display device

Next, a method for producing the sealing sheet 1 will be explained.

In the production of the sealing sheet 1, for example, the above-mentioned sealing material (preferably, varnish containing an organic solvent) is prepared, and the sealing material is coated on the surface of the base film 3 by a known method.

The sealing material is prepared by mixing the above-mentioned resin component, curing agent and additive (preferably the above-mentioned organic solvent) in the above-mentioned ratio. The components can be dispersed by a ball mill, or charged into a flask and stirred, or kneaded by a three-roll mill, for example, to mix them.

Further, examples of the method of applying the sealing material include screen printing, a dispenser, and an application roller.

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

The heating temperature is a temperature at which the sealing material is dried without being cured, and is, for example, 20 ℃ or higher, preferably 90 ℃ or higher, for example, 120 ℃ or lower, and preferably less than 100 ℃. 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, the coating film is dried, and the sealing layer 2 formed of the sealing material can be prepared. Next, a release film 4 is attached to the surface of the sealing layer 2.

By the above operation, the sealing sheet 1 is manufactured.

< manufacture of image display device >

Next, a method for manufacturing an organic EL display with a touch sensor (hereinafter, referred to as an organic EL display 10) as an embodiment of a method for manufacturing an image display device will be described with reference to fig. 2, 3A to 3C, and 4.

In addition, in the present embodiment, an organic EL display with a touch sensor is given as an example of an 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. Among such image display devices, an organic EL display is preferable, an organic EL display with a touch sensor is more preferable, and an organic EL display with a capacitance type touch sensor is particularly preferable. That is, the sealing material is preferably a sealing material for an organic EL display, more preferably a sealing material for an organic EL display with a touch sensor, and the sealing sheet is preferably a sealing sheet for an organic EL display, more preferably a sealing sheet for an organic EL display with a touch sensor.

The method for manufacturing the organic EL display 10 includes the steps of: a step of preparing the component mounting unit 11 (see fig. 3A); a step of attaching the sealing layer 2 of the sealing sheet 1 to the substrate 13 so as to embed the organic EL element 12 covered with the barrier layer 16 (see fig. 3B); a step of attaching a cover glass or a barrier film 15 to the sealing layer 2 (see fig. 3C); and a step of curing the sealing layer 2 to form the sealing member 14 (see fig. 2).

In the method of manufacturing the organic EL display 10, first, as shown in fig. 3A, the element mounting unit 11 is prepared. The element-mounting unit 11 includes a substrate 13, an organic EL element 12 as an example of an optical element (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 contact of moisture in the atmosphere with the organic EL element 12. The barrier layer 16 includes a 1 st inorganic barrier layer 17, a planarization layer 19, and a 2 nd inorganic barrier layer 18.

The 1 st inorganic barrier layer 17 is disposed on the upper surface and the side surfaces of the organic EL element 12 so as to surround the organic EL element 12. Examples of the material of the 1 st inorganic barrier layer 17 include metal oxides (e.g., aluminum oxide, silicon oxide, copper oxide, etc.), metal nitrides (e.g., aluminum nitride, silicon nitride, etc.), and the like. The material of the 1 st inorganic barrier layer 17 may be used alone or in combination of 2 or more. Among the materials of the 1 st inorganic barrier layer 17, a metal nitride is preferable, and silicon nitride is more preferable.

The planarization layer 19 is disposed on the upper surface of the 1 st inorganic barrier layer 17. Examples of the material of the planarizing layer 19 include known resin materials.

The 2 nd 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 2 nd inorganic barrier layer 18 include the same materials as those of the 1 st inorganic barrier layer 17.

The electrodes (not shown) constitute sensors of the organic EL display with touch sensors. An electrode (not shown) is located between the substrate 13 and a sealing member 14 (described later). For example, the electrode (not shown) may be located within the substrate 13 or may be located on the organic EL element 12.

Next, as shown by the imaginary line in fig. 1, the release film 4 is peeled off from the sealing sheet 1 and removed. Further, as shown in fig. 3B, after the sealing sheet 1 is heated to the bonding temperature, the sealing layer 2 is bonded to the substrate 13 so that the organic EL element 12 covered with the barrier layer 16 is embedded in the sealing layer 2.

The pasting temperature is a temperature at which the sealing layer 2 is softened without being cured, and is, for example, 40 ℃ or higher, preferably 60 ℃ or higher, for example, 120 ℃ or lower, preferably 100 ℃ or lower.

Next, as shown by the imaginary line in fig. 3B, the base film 3 is peeled off from the sealing layer 2 and removed. Further, as shown in fig. 3C, a cover glass or a barrier film 15 is attached to the upper surface of the sealing layer 2. Although not shown, the cover glass or the barrier film 15 includes a glass plate and electrodes provided on a lower surface of the glass plate and constituting sensors of the organic EL display with touch sensors.

As shown in fig. 4, the sealing layer 2 may be attached to the cover glass or the barrier film 15, and then the sealing layer 2 may be attached to the component mounting unit 11.

Next, as shown in fig. 2, the sealing layer 2 is heated to a curing temperature, and the sealing layer 2 is cured to form the sealing member 14.

The curing temperature is higher than the above-mentioned drying temperature. The curing temperature is, for example, 70 ℃ or higher, preferably 80 ℃ or higher, for example, 150 ℃ or lower, preferably 120 ℃ or lower. The curing time is, for example, 10 minutes or more, preferably 30 minutes or more, for example, 2 hours or less, preferably 60 minutes or less.

Through the above operation, the organic EL display 10 including the element-mounting unit 11, the sealing member 14, and the cover glass or the barrier film 15 is manufactured. Such an organic EL display 10 is a capacitance type touch panel. The organic EL display 10 has an embedded structure in which the organic EL element 12 is disposed between 2 electrodes constituting the sensor, or a surface-embedded structure in which 1 of the 2 electrodes constituting the sensor is disposed 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 dielectric constant of the sealing member 14 is, for example, 3.0 or more, preferably 3.2 or more, and is, for example, less than 3.80, preferably 3.70 or less. The dielectric constant can be measured by the method described in the examples described later.

If the dielectric constant of the sealing member 14 is not less than the lower limit, the degree of freedom in material selection can be improved. If the dielectric constant of the sealing member 14 is not more than the upper limit, it is possible to suppress the occurrence of malfunction in an organic EL display or the like with a touch sensor.

The haze value of the sealing member 14 is, for example, 0.1 or more, for example, less than 5.0%, preferably 4.0% or less, more preferably 3.0% or less, particularly preferably 2.0% or less, and particularly preferably less than 1.0. The haze value can be measured by the method described in the examples described below.

If the haze value of the sealing member 14 is not more than the above upper limit, it is possible to achieve an improvement in visibility of a display (including an organic EL display with a touch sensor).

The sealing member 14 has a moisture permeability of, for example, 20g/m²24h or more, e.g. 50g/m²24h or less, preferably less than 45g/m²24h, more preferably 40g/m²24h or less. Here, the moisture permeability can be measured by the method described in the examples described later.

If the moisture permeability of the sealing member 14 is not more than the above upper limit, deterioration of the optical element sealed by the sealing member 14 can be suppressed.

< action Effect >

However, the sealing member of the liquid crystal display is provided in a frame shape so as to surround the liquid crystal disposed between the substrate 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 as to embed the organic EL element therein. Therefore, the sealing member of the organic EL display has a larger influence on 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 the organic EL display does not require a low dielectric constant to the extent required for a sealing member of a general semiconductor component.

The present inventors have found that the dielectric constant of a sealing member formed of a sealing material can be adjusted to a range required for an image display device, particularly an organic EL display, by adding a styrene oligomer, which is generally used as a thickener or the like, to a resin component of the sealing material.

However, if a styrene-based oligomer is added to the resin component, the following disadvantages occur: the sealing member is clouded, and the transparency of the sealing member is lowered, so that high transparency required for the sealing member of an image display device (particularly, an organic EL display) cannot be secured.

Accordingly, the present inventors have made various studies on the composition of the resin component and have found the following findings: the present inventors have completed the present invention by including an epoxy resin having a biphenyl skeleton together with a styrene-based oligomer in a resin component, thereby enabling a reduction in dielectric constant of a sealing member and ensuring high transparency.

Since the above-mentioned sealing material contains the epoxy resin having a biphenyl skeleton and the styrene-based oligomer as the resin components, the dielectric constant of the sealing member can be reduced to a range required for an image display device (particularly, an organic EL display), and high transparency required for the image display device (particularly, the organic EL display) can be ensured.

The content ratio of the styrene-based oligomer in the resin component is preferably in the above range. Therefore, the transparency of the sealing member can be improved.

Further, as for the styrenic oligomer, a homopolymer of a monomer having a styrene skeleton is preferably used alone. Therefore, the moisture permeability of the sealing member can be reduced, and deterioration of a display element (for example, an organic EL element or the like) sealed by the sealing member can be suppressed.

The resin component preferably contains an aliphatic hydrocarbon resin. Therefore, the transparency of the sealing member can be more reliably improved.

The content ratio of the aliphatic hydrocarbon resin to the styrene-based oligomer is preferably in the above range. Therefore, the transparency of the sealing member can be more reliably improved.

In the resin component, the content ratio of the aliphatic hydrocarbon resin is preferably not more than the upper limit, and the content ratio of the sum of the styrene-based oligomer and the aliphatic hydrocarbon resin is preferably not more than the upper limit. Therefore, the moldability of the sealing material can be appropriately adjusted, and the sealing material can be stably molded into a sheet shape.

Further, as shown in fig. 1, the sealing sheet 1 has a sealing layer 2 formed of a sealing material. Therefore, the workability of the sealing material can be improved. Further, in the sealing member, a reduction in dielectric constant can be achieved, and high transparency can be ensured.

< modification example >

In the modification, the same members and steps as those in the above-described 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 sealing sheet for an image display device of the present invention is not limited thereto. 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 provided. That is, the image display device sealing sheet may be constituted only by the sealing layer 2, or may be provided with the sealing layer 2 and either 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 a built-in structure in which the organic EL element 12 is disposed between 2 electrodes constituting the sensor, or a surface-mounted structure in which 1 of the 2 electrodes is disposed on the organic EL element 12, but is not limited thereto.

For example, as shown in fig. 5, the organic EL display 20 may have an external fitting structure in which 2 electrodes constituting a sensor are arranged on the upper side of the sealing member 14. The organic EL display 20 includes the element mounting unit 11, the sealing member 14, and the sensor unit 25.

The sensor unit 25 includes a glass substrate 23, an adhesive layer 21, and a cover glass 22. The glass substrate 23 is disposed on the upper surface of the sealing member 14. The glass substrate 23 includes transparent electrodes constituting sensors of the organic EL display with touch sensors. The adhesive layer 21 is disposed between the glass substrate 23 and the cover glass 22, and bonds the glass substrate 23 and the cover glass 22 together. Cover glass 22 is disposed on the upper side of adhesive layer 21. The cover glass 22 includes electrodes constituting sensors of the organic EL display with touch sensors. In the organic EL display 20, the substrate 13 does not include an electrode.

The above-described modifications exhibit the same operational advantages as the above-described one embodiment. The above-described embodiments and modifications can be combined as appropriate.