JP2016222840A - Encapsulation material for organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encapsulation material for an organic EL element excellent in encapsulation property as well as excellent in flexibility and visibility.SOLUTION: There is provided an encapsulation material for an organic EL element using a (meth)acrylic copolymer (A) having weight average molecular weight of 10,000 to 1,000,000 and obtained by polymerizing a monomer mixture containing a (meth)acrylate-based macro monomer (a) having a double bond-containing carboxylic acid ester group with number average molecular weight of 500 or more and less than 6000 at a singe terminal and a vinyl monomer (b).SELECTED DRAWING: None

Description

  The present invention relates to a transparent sealing material for organic EL elements.

A wide variety of copolymers having different physical properties have been synthesized by copolymerizing vinyl monomers alone or various vinyl monomer mixtures. Among these, a copolymer using a single vinyl monomer cannot meet various physical property requirements, and therefore, generally, a mixture of two or more types of vinyl monomers or a heterogeneous copolymer can be used. Mixing methods have been used. However, when various vinyl monomer mixtures are simply copolymerized, the characteristics of each monomer unit tend to be averaged. Further, when two or more kinds of copolymers are simply mixed, the copolymers are often inferior to the characteristics of each monomer unit without being mixed.
In order to solve these problems, a copolymer using a macromonomer has been studied. A macromonomer is a high molecular weight monomer having a polymerizable functional group. A copolymer obtained by copolymerizing a macromonomer has a characteristic that individual characteristics can be expressed without impairing the characteristics of the macromonomer portion and the monomer unit copolymerized with the macromonomer. Therefore, for example, various copolymers using this type of macromonomer have also been proposed in the field of adhesives.

By the way, an organic electroluminescence element (organic EL element) basically has a configuration in which an anode layer, a light emitting layer, and a cathode layer are sequentially formed on a substrate made of glass or the like. In order to improve performance, a functional layer may be provided between each layer.
The organic EL element having the above-described configuration can emit light by energizing between the anode layer and the cathode layer.
Further, such an organic EL element has properties such as low voltage driving, high efficiency, and high brightness, and is a self-luminous device, so that it can be reduced in thickness and weight. . For this reason, applications have been expanded widely from backlights for liquid crystal displays and night lights to flat displays such as computer terminal displays and television screen displays, and are expected as next-generation materials that can replace liquid crystals.
In addition, the organic EL element is expected as a flexible display because all the constituent elements can be made of a solid material.
However, the solid organic compound constituting the light emitting layer of the organic EL element is easily affected by moisture, oxygen, etc., and its characteristics are likely to deteriorate. For example, when the organic EL element is driven in the atmosphere, a non-light emitting portion (dark spot) is generated due to the intrusion of moisture into the light emitting layer. The occurrence of this dark spot becomes a serious defect in a light source such as a display. Therefore, in order to extend the lifetime of the organic EL element, it is necessary to improve the hermeticity of the element.
In order to prevent such problems, various techniques for sealing a light emitting layer of an organic EL element and suppressing contact with moisture and oxygen have been studied.
Patent Document 1 proposes an organic EL element that eliminates the influence of moisture, oxygen, etc. as much as possible by covering a light emitting layer with a sealing layer in which a barrier layer made of an inorganic film or the like, a resin layer, and a barrier layer are sequentially laminated. Has been. However, when a hard resin layer is used, the resin layer is not sufficiently fixed, and it is insufficient to seal the influence of moisture, oxygen, and the like from the outside. Also, the flexibility was not sufficient.

JP 2001-307873 A

  An object of the present invention is to provide a transparent sealing material that can prevent the influence of moisture, oxygen, and the like from the outside in an organic EL element and has flexibility.

  The present invention has a weight average molecular weight of 10,000 to 1,000,000 obtained by polymerizing a monomer mixture containing a macromonomer (a) having a number average molecular weight of 500 or more and less than 6000 and a vinyl monomer (b). It is related with the sealing material for organic EL used for a certain (meth) acrylic-type copolymer (A).

  Since the (meth) acrylic copolymer (A) of the present invention has the characteristics of the macromonomer portion and the monomer unit copolymerized with the macromonomer, the obtained sealing material has sufficient sealing properties. And prevents entry of moisture and oxygen from the outside. In addition, an organic EL element excellent in flexibility can be provided.

  Next, the present invention will be described based on an embodiment. However, the present invention is not limited to the embodiment described below.

<Organic EL element sealing material>
The organic EL device sealing material of the present invention is a weight average molecular weight obtained by polymerizing a monomer mixture containing a macromonomer (a) having a number average molecular weight of 500 or more and less than 6000 and a vinyl monomer (b). The (meth) acrylic copolymer (A) having a weight average molecular weight of 10,000 to 1,000,000 is used.

<Macromonomer (a)>
A macromonomer generally means a polymer compound having a polymerizable group introduced at the end of a polymer. The number average molecular weight of the macromonomer (a) in the present invention is 500 or more and less than 6000. The number average molecular weight is preferably 800 to 5500, and more preferably 1000 to 4500, from the relationship of the balance between adhesive force and coating property.

  Although various things are used for the monomer which comprises macromonomer (a), For example, (meth) acrylic acid methyl, (meth) acrylic acid ethyl, (meth) acrylic acid n-propyl, (meth) acrylic Isopropyl acid, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, ( (Meth) acrylate lauryl, (meth) acrylate stearyl, (meth) acrylate isostearyl (meth) hexadecyl acrylate, (meth) acrylate nonyl, (meth) acrylate isononyl, (meth) acrylate phenyl, (meth) ) Benzyl acrylate, cyclohexyl (meth) acrylate, tetrahydrofur (meth) acrylate Ril, isobornyl (meth) acrylate, 3,5,5-trimethylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyl (meth) acrylate Oxyethyl, terpene acrylate and derivatives thereof, hydrogenated rosin acrylate and derivatives thereof, docosyl (meth) acrylate, glycidyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, Hydroxyl group content such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol (meth) acrylate ( (Meth) acrylic acid ester; T) Acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropyl Phthalic acid, 2- (meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxypropylmaleic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxypropylsuccinic acid, crotonic acid, Carboxylic group-containing vinyl monomers such as fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate; acid anhydride group-containing vinyl monomers such as maleic anhydride and itaconic anhydride; (meth) Glycidyl acrylate, glycylic α-ethyl acrylate And epoxy group-containing vinyl monomers such as (meth) acrylic acid 3,4-epoxybutyl; amino group-containing (meth) acrylic acid esters such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate (Meth) acrylamide, Nt-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-isopropylacrylamide, hydroxyethyl acrylamide, N-methoxymethyl (meth) acrylamide, N- Vinyl monomers containing amide groups such as butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic acid amide, maleimide; styrene, α-methylstyrene, vinyl toluene, (meth) acrylonitrile, vinyl chloride, vinyl acetate, Propio Vinyl monomers such as vinyl acetate divinylbenzene, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, triethylene glycol di ( Many such as (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, N, N'-methylenebis (meth) acrylamide Functional vinyl monomers, acryloylmorpholine, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, (meth) acrylate N-butoxyethyl laurate, isobutoxyethyl (meth) acrylate, t-butoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, nonylphenoxy (meth) acrylate Ethyl, 3-methoxybutyl (meth) acrylate, acetoxyethyl (meth) acrylate, “Placcel FM” (Caprolactone addition monomer, trade name, manufactured by Daicel Chemical Industries, Ltd.), “Blenmer PME-100” (NOF Corporation) ) Methoxypolyethyleneglycol methacrylate (ethylene glycol chain is 2), trade name), "Blenmer PME-200" (NOF Corporation methoxypolyethyleneglycol methacrylate (ethylene glycol chain is 4)) , Product name), "Blemma PME-400 "(manufactured by NOF Corporation, methoxypolyethylene glycol methacrylate (trade name of ethylene glycol is 9), trade name)," Blemmer 50POEP-800B "(manufactured by NOF Corporation, octoxypolyethylene glycol-polypropylene) Glycol-methacrylate (ethylene glycol chain is 8 and propylene glycol chain is 6), trade name) and "Blenmer 20ANEP-600" (NOF Corporation nonylphenoxy (ethylene glycol-polypropylene glycol)) Monoacrylate, trade name), “Blemmer AME-100” (trade name) manufactured by NOF Corporation, “Blemmer AME-200” (trade name, manufactured by NOF Corporation) and “Blemmer 50AOEP-800B” ( NOF Corporation, trade name) Silapre FM-0711 (trade name, manufactured by JNC Corporation), Silaplane FM-0721 (trade name, manufactured by JNC Corporation), Silaplane FM-0725 (trade name, manufactured by JNC Corporation), Silaplane TM-0701 (trade name, manufactured by JNC Corporation), Silaplane TM-0701T (trade name, manufactured by JNC Corporation), X-22-174DX (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), X- 22-2426 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name), X-22-2475 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name), (meth) acrylic acid-2-isocyanatoethyl and the like.

Among these, methacrylic acid esters are preferable from the viewpoint of improving the glass transition temperature, ease of polymerization, and holding power. More preferably, methyl methacrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, (meth) acrylic Acid hydroxyethyl and hydroxypropyl (meth) acrylate.
Moreover, it is preferable that a macromonomer (a) contains 50-100 mass parts of methacrylic acid ester as a structural component. More preferably, it is 70-100 mass parts, More preferably, it is 90-100 mass parts.

  As the macromonomer (a) in the present invention, those having a terminal structure of the following formula (1) in which a polymerizable group is introduced at the terminal of the poly (meth) acrylate segment are preferable. In the present invention, “(meth) acrylic acid” means “acrylic acid” or “methacrylic acid”.

  In the formula (1), R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. The alkyl group, cycloalkyl group, aryl group or heterocyclic group can have a substituent.

  Examples of R include a branched or straight chain alkyl group having 1 to 20 carbon atoms. Specific examples of the branched or straight chain alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, t-butyl group, i-butyl group, and pentyl. Group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group and icosyl group. Among these, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, pentyl, hexyl, heptyl and octyl groups are preferred because of their availability. A methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group and a t-butyl group are more preferable.

  R includes, for example, a cycloalkyl group having 3 to 20 carbon atoms. Specific examples of the cycloalkyl group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and an adamantyl group. From the viewpoint of availability, a cyclopropyl group, a cyclobutyl group and an adamantyl group are preferred.

  R includes, for example, an aryl group having 6 to 18 carbon atoms. Specific examples of the aryl group having 6 to 18 carbon atoms include a phenyl group and a naphthyl group.

R includes, for example, a heterocyclic group having 5 to 18 carbon atoms. Specific examples of the heterocyclic group for R or R ^{1 to} R ⁿ include a γ-butyrolactone group and an ε-caprolactone group.

  Examples of the substituent that R may have include an alkyl group, an aryl group, a carboxyl group, an alkoxycarbonyl group (—COOR ′), a cyano group, a hydroxyl group, an amino group (—NR′R ″), an amide group ( -CONR'R ''), a halogen, an allyl group, an epoxy group, an alkoxy group (-OR '), a siloxy group, or a group or atom selected from the group consisting of a hydrophilic group or an ionic group. R ′ or R ″ each independently represents the same hydrogen atom, alkyl group, cycloalkyl group, or aryl group as R.

Examples of the alkoxycarbonyl group for the substituent include a methoxycarbonyl group.
Examples of the amino group of the substituent include an amino group, a monomethylamino group, and a dimethylamino group. Examples thereof include an N-methylcarbamoyl group and an N, N-dimethylcarbamoyl group.
Examples of the amide group of the substituent include a carbamoyl group (—CONH ₂ ), an N-methylcarbamoyl group (—CONHMe), and an N, N-dimethylcarbamoyl group (dimethylamide group: —CONMe ₂ ).

Examples of the halogen for the substituent include fluorine, chlorine, bromine and iodine.
As an alkoxy group of the said substituent, a C1-C12 alkoxy group is mentioned, for example, A methoxy group is mentioned as a specific example.
Examples of the hydrophilic or ionic group of the substituent include an alkali salt of a carboxyl group or an alkali salt of a sulfoxyl group, a poly (alkylene oxide) group such as a polyethylene oxide group and a polypropylene oxide group, and a quaternary ammonium base. Of the cationic substituent.
R is preferably an alkyl group or a cycloalkyl group, and more preferably an alkyl group.
Z is a terminal group of the macromonomer (a). Examples of the terminal group of the macromonomer (a) include a group derived from a hydrogen atom and a radical polymerization initiator, similarly to the terminal group of a polymer obtained by known radical polymerization.

  Of the formula (1), the structure of the following formula (2) is particularly preferable.

In Formula (2), n is a natural number of 40-100,000. R and R ^{1 to} R ⁿ are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group. The alkyl group, cycloalkyl group, aryl group or heterocyclic group can have a substituent. X ^{1 to} X ⁿ are each independently a hydrogen atom or a methyl group. Z is a terminal group.
Examples of R and R ^{1 to} R ⁿ include the same groups as R in formula (1), and examples of Z include the same end groups as Z in formula (1). In addition, Z in the formula (2) is preferably a polymerizable functional group. Examples of the terminal polymerizable functional group include a methacryloyl group, an acryloyl group, a vinyl group, and a group similar to the terminal on the left side of the formula (2).

Glass transition temperature (Tga)
In the present invention, the glass transition temperature (Tga) of the macromonomer (a) is preferably 0 to 120 ° C. 10-110 degreeC is more preferable from the point which can express sufficient holding power, when it uses as an adhesive, and 30-100 degreeC is further more preferable.
Tga can be measured with a differential scanning calorimeter (DSC).

Production Method of Macromonomer (a) Macromonomer (a) can be produced by a known method. Examples of the method for producing the macromonomer (a) include a method using a cobalt chain transfer agent, a method using an α-substituted unsaturated compound such as α-methylstyrene dimer as a chain transfer agent, and a polymerizable group chemically. And a method by thermal decomposition.
Among these, the production method of the macromonomer (a) is preferably a method of producing a macromonomer (a) using a cobalt chain transfer agent in terms of using a catalyst having a small number of production steps and a high chain transfer constant. In addition, the terminal group Z of the macromonomer (a) at the time of manufacturing using a cobalt chain transfer agent becomes a polymerizable functional group having the same structure as the left side structure of the formula (2).

  Examples of the method for producing the macromonomer (a) using a cobalt chain transfer agent include aqueous dispersion polymerization methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. An aqueous dispersion polymerization method is preferred from the viewpoint that the recovery step is simple.

<Monomer mixture>
The monomer mixture includes a macromonomer (a) and a vinyl monomer (b).
In the monomer mixture, the content of the macromonomer (a) is preferably 7 to 40% by mass. When the content of the macromonomer (a) is 7% by mass or more, the retention tends to be good when used as an adhesive. When it is 40% by mass or less, the coatability tends to be good. The content of the macromonomer (a) is preferably 8 to 30% by mass, more preferably 9 to 20% by mass, from the viewpoint of the holding power of the pressure-sensitive adhesive and the coating property.

<(Meth) acrylic copolymer (A)>
The (meth) acrylic copolymer (A) is a copolymer obtained by polymerizing a monomer mixture containing the macromonomer (a) and the vinyl monomer (b). As a production method, it can be produced by a known polymerization method such as a solution polymerization method, a suspension polymerization method and an emulsion polymerization method. In this invention, since it uses as an adhesive composition, a solution polymerization method is preferable.

In the present invention, in the (meth) acrylic copolymer (A), a polymer having only repeating units derived from the macromonomer (a), one or more repeating monomers derived from the vinyl monomer (b). It can contain at least 1 sort (s) chosen from the polymer which has a unit, an unreacted macromonomer (a), and an unreacted vinyl monomer (b).
Further, the (meth) acrylic copolymer (A) is a block copolymer having repeating units derived from the macromonomer (a) and the vinyl monomer (b), and a repeating unit derived from the macromonomer (a) in the side chain. It contains at least one selected from graft copolymers of vinyl monomers having units.

Vinyl monomer (b)
The vinyl monomer (b) used in the present invention can be the same as the monomer for obtaining the macromonomer (a). In particular, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-butyl acrylate, ethyl acrylate, and the like can exhibit flexibility as an adhesive, and are (meth) acrylic copolymers (because they are hydrophobic) It is preferable because water absorption of A) can be suppressed and electrical characteristics such as the relative dielectric constant of (meth) acrylic copolymer (A) can be adjusted.
In addition, (meth) acrylic acid, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, methyl (meth) acrylate, styrene, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. preferable.

Weight average molecular weight
The (meth) acrylic copolymer (A) has a weight average molecular weight of 10,000 to 1,000,000. When it is 10,000 or more, the durability of the pressure-sensitive adhesive composition tends to be good. If it is 1,000,000 or less, the coatability tends to be good. From the viewpoint of coatability, the weight average molecular weight of the (meth) acrylic copolymer (A) is preferably 5 to 700,000, more preferably 12 to 700,000, and still more preferably 15 to 500,000.

Glass transition temperature (TgB)
In the present invention, the glass transition temperature (TgB) of the copolymer (B) obtained by polymerizing the vinyl monomer (b) is the flexibility of the pressure-sensitive adhesive resin composition at room temperature and appropriate adhesiveness ( In order to have (tackiness), it is preferably −100 ° C. to 10 ° C. TgB is more preferably −65 ° C. to −0 ° C. Especially preferably, it is -60 degreeC--10 degreeC or less.

TgB means a value calculated by Fox's formula from the glass transition temperature and the composition ratio of the polymer obtained from the homopolymer of monomer (b).
In addition, the calculation formula of Fox is a calculation value calculated | required by the following formula | equation. Brandrup, Interscie
nce, 1989].
1 / (273 + Tg) = Σ (Wi / (273 + Tgi))
[Wherein Wi represents the weight fraction of monomer i, and Tgi represents Tg (° C.) of the homopolymer of monomer i]

The glass transition temperatures (Tga) and (TgB) preferably have the relationship of the following formula (3) from the viewpoint that the characteristics of the macromonomer part and the monomer unit copolymerized with the macromonomer can be sufficiently expressed. .
Tga> TgB (3)
More preferably, Tga-TgB> 50 ° C., and most preferably Tga-TgB> 80 ° C.

<Adhesive composition used for sealing material for organic EL element>
The pressure-sensitive adhesive composition used for the organic EL device sealing material of the present invention contains a (meth) acrylic copolymer (A).
In the said adhesive composition, you may contain the well-known component mix | blended with the normal adhesive composition. For example, a filler can be added to impart heat resistance, thermal conductivity, flame retardancy, electrical conductivity, and the like. Examples of the filler include metal powders such as zinc oxide powder and titanium oxide powder, carbon black such as acetylene black, talc, glass powder, silica powder, conductive particles, and inorganic fillers such as glass powder; polyethylene powder, Examples thereof include organic fillers such as polyester powder, polyamide powder, fluororesin powder, polyvinyl chloride powder, epoxy resin powder, and silicone resin powder. These fillers may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition can also be used after being crosslinked by ultraviolet irradiation, electron beam irradiation, heating or the like. For example, a method of adding a crosslinking agent capable of chemically bonding to a reactive group such as a hydroxyl group introduced into the (meth) acrylic copolymer (A) and reacting by heating or curing, or (meth) acryloyl as a crosslinking agent Examples thereof include a method in which a polyfunctional (meth) acrylate having two or more groups, an acrylate having a nitrogen atom introduced, and a reaction initiator such as a photopolymerization initiator are added and reacted.
Furthermore, a functional group can be introduced into the (meth) acrylic copolymer (A) to form a pressure-sensitive adhesive composition containing a crosslinking agent or a polymerization initiator, or it can be used after being crosslinked. Examples of the crosslinking method include an isocyanate crosslinking system, an epoxy crosslinking system, a metal chelate crosslinking system, a photocrosslinking system, a melamine crosslinking system, an aziridine crosslinking system, and the like, and these can be used in combination.

  Examples of the isocyanate-based crosslinking agent include aromatic polyisocyanates such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated products of the above aromatic polyisocyanates. Aliphatic or alicyclic polyisocyanates, dimers or trimers of these polyisocyanates, adducts composed of these polyisocyanates and polyols such as trimethylolpropane, and the like. Or 2 or more types can be used together.

  Examples of the epoxy-based crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A type epoxy resin, N, N, N ′, N′-tetraglycidyl. -M-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine and the like.

  Examples of the metal chelate compound include those in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of the polyvalent metal include aluminum, nickel, chromium, copper, iron, tin, titanium, zinc, cobalt, manganese, and zirconium.

  Examples of the organic compound that can be covalently or coordinately bonded include those having oxygen in a ketone compound such as acetylacetone, an alkyl ester, an alcohol compound, a carboxylic acid compound, and an ether compound.

The photocuring system can be cross-linked by UV irradiation or the like by adding a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups as a cross-linking agent and a reaction initiator such as a photopolymerization initiator. Examples of the crosslinking agent include polyfunctional (meth) acrylates having two or more (meth) acryloyl groups, or 2 organic functional groups such as isocyanate groups, epoxy groups, melamine groups, glycol groups, siloxane groups, and amines. Polyfunctional organic functional group resin having at least one, or organic metal compound having metal complex such as zinc, aluminum, sodium, zirconium, calcium, triethylene glycol diacrylate, polyalkylene glycol diacrylate, bisphenol A-EO / PO Modified diacrylate, alkoxylated hexanediol diacrylate , Polyisobutylene diacrylate, alkoxylated trimethylolpropane triacrylate, alkoxylated pentaerythritol triacrylate, alkoxylated pentaerythritol tetraacrylate, alkoxylated dipentaerythritol pentaacrylate, caprolactone modified dipentaerythritol pentaacrylate and hexaacrylate And (meth) acrylate.
Examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl) -Propionyl) benzyl} phenyl] -2-methyl-propan-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), methyl phenylglyoxylic acid 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3 ' -Dimethyl-4-methoxybenzophenone, 4- (1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl) benzophenone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like.

  If necessary, tackifier resins, antioxidants, light stabilizers, metal deactivators, anti-aging agents, hygroscopic agents, rust inhibitors, hydrolysis inhibitors, fillers, plasticizers, defoamers Various additives such as an agent, a leveling agent, a desiccant, and a softening agent can be appropriately contained. A reaction catalyst (a tertiary amine compound, a quaternary ammonium compound, a tin laurate compound, etc.) may be appropriately contained.

  As a kind of antioxidant, phenol type, phosphorus type, hydroxylamine type, sulfur type etc. are mentioned, for example. Of these, phenol-based and phosphoric acid-based antioxidants that are less colored after heating are preferable. These may be used alone or in combination of several kinds. It is preferable that the compounding quantity of the said antioxidant shall be the range of 0.1-5 mass parts with respect to a (meth) acrylic-type copolymer.

<Organic EL device>
The organic EL device according to the present invention can have various configurations known in the technical field. The organic EL device of the present invention includes a laminate including a pair of opposed electrodes, that is, an anode and a cathode, and a light emitting unit having at least an organic light emitting layer disposed between the electrodes. The laminate is sealed with a sealing material having an adhesive layer according to the present invention. A barrier layer may be provided on both sides or one side of the adhesive layer. Moreover, although not limited to the structure demonstrated below, the organic EL element of this invention can have the following structures, for example.

  In the organic EL device of the present invention, a laminate composed of two electrodes and a light emitting unit disposed between the electrodes may be, for example, a single light emitting unit or a combination of two or more light emitting units. As can be seen from some of the built-in ones, it can have various layer configurations. In addition, the structure of a laminated body is demonstrated below.

  In the organic EL element, the laminate is supported by a substrate. The substrate used here is usually made of a hard material, for example, an inorganic material such as zirconia-stabilized yttrium (YSZ), glass or metal, or a resin material such as polyester, polyimide or polycarbonate. There is no restriction | limiting in the shape, a structure, a dimension, etc., and a board | substrate can be selected optimal according to the structure of the target EL element. A typical substrate is in the form of a plate. The substrate may be colorless and transparent, translucent, or opaque. Further, the substrate may be provided with a moisture permeation preventive layer (gas barrier layer) or the like as required.

  The organic EL device according to the present invention can additionally have various components known in the field of organic EL devices in addition to the components described above.

  As described above, the organic EL element can have a sealing cap (also referred to as a sealing plate) in the outermost layer. The sealing cap is usually made of a hard material, and a typical example is glass or metal.

  According to another method, a protective film can be provided on the outermost layer of the organic EL element. This protective film is preferably a protective film having a water vapor barrier property or an oxygen barrier property, and is also referred to as a gas barrier layer or a gas barrier film. Here, it is referred to as “gas barrier film” or “gas barrier film layer”. The gas barrier film layer can be formed from various materials having a water vapor barrier property. Suitable materials include, for example, polyethylene trifluoride, polytrifluoroethylene chloride (PCTFE), polyimide, polycarbonate, polyethylene terephthalate. Silicon oxide, silicon nitride, aluminum oxide, diamond-like carbon, etc., using polymer layers such as alicyclic polyolefin, ethylene-vinyl alcohol copolymer, etc., or laminates thereof, and film formation methods such as sputtering on the polymer layer And those coated with an inorganic thin film. Although the thickness of the gas barrier film layer can be changed in a wide range, it is usually in the range of about 10 to 500 μm.

  The sealing material for organic EL elements of the present invention exhibits excellent sealing performance due to domain formation by microphase separation of main chain and side chain and entanglement effect as a branched polymer, and has flexibility.

  Examples and comparative examples are shown below, and the resin composition of the present invention will be described in more detail. However, the present invention is not limited to these. In the present embodiment, “part” means “part by mass”.

<Synthesis of Macromonomer (a-1)>
<Production of Dispersant 1>
In a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer, 900 parts of deionized water, 60 parts of 2-sulfoethyl sodium methacrylate, 10 parts of potassium methacrylate and 12 parts of methyl methacrylate (MMA) are stirred. The temperature was raised to 50 ° C. while replacing the inside of the polymerization apparatus with nitrogen. Into this, 0.08 part of 2,2′-azobis (2-methylpropionamidine) dihydrochloride was added as a polymerization initiator, and the temperature was further raised to 60 ° C. After the temperature increase, MMA was continuously added dropwise at a rate of 0.24 part / minute for 75 minutes using a dropping pump. The reaction solution was held at 60 ° C. for 6 hours and then cooled to room temperature to obtain Dispersant 1 having a solid content of 10% by mass as a transparent aqueous solution.

In a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer, 145 parts of deionized water, 0.1 part of sodium sulfate and 0.25 part of dispersant 1 (solid content 10% by mass) were stirred and stirred uniformly. Solution. Next, 100 parts of MMA, 0.0045 parts of bis [(difluoroboryl) diphenylglyoxymate] cobalt (II) as a chain transfer agent and “Perocta O” (registered trademark) (1,1, (3,3-tetramethylbutylperoxy 2-ethylhexanoate, manufactured by NOF Corporation) 0.45 was added to form an aqueous suspension.
Next, the inside of the polymerization apparatus was purged with nitrogen, heated to 80 ° C. and reacted for 1 hour, and further heated to 90 ° C. and held for 1 hour in order to increase the polymerization rate. Thereafter, the reaction solution was cooled to 40 ° C. to obtain an aqueous suspension containing a macromonomer. This aqueous suspension was filtered, and the filtrate was washed with deionized water, dehydrated, and dried at 40 ° C. for 16 hours to obtain a macromonomer (a-1). The number average molecular weight of this macromonomer (a-1) was 1900, and the glass transition temperature measured by DSC was 73 ° C.

<Production of Macromonomer (a-2) to (a-5)>
Manufactured in the same manner as the macromonomer (a-1) except that the monomer added to the dispersant 1, the polymerization initiator, and the chain transfer agent were changed to the amounts (parts) shown in Table 1. The number average molecular weight (Mn) and glass transition temperature (Tga) of the obtained macromonomer (a) are shown together in Table 1.

MMA: Methyl methacrylate IBXMA: Isobornyl methacrylate

  The glass transition temperature (Tga) of the macromonomer (a) and the molecular weight of the macromonomer (a) were measured by the following methods.

Glass transition temperature (Tga) of macromonomer (a)
Using a differential inspection calorimeter (DSC SmartLoader manufactured by Rigaku), the temperature was measured at a heating rate of 5 ° C./min in a nitrogen atmosphere. In addition, aluminum oxide was used as a standard substance.
Molecular weight of macromonomer (a) / macromonomer (a)
It measured using gel permeation chromatography (GPC) (HLC-8320 by Tosoh Corporation). After adjusting 0.2% by mass of the tetrahydrofuran solution of the macromonomer (a), 10 μl of the above solution was injected into a device equipped with a Tosoh column (TSKgel SuperHZM-M × HZM-M × HZ2000, TSKguardcolumn super HZ-L). The flow rate was 0.35 ml / min, the eluent was tetrahydrofuran (stabilizer BHT), the column temperature was 40 ° C., and the number average molecular weight (Mn) was calculated in terms of standard polystyrene.

[Production Example 1]
<Production of (meth) acrylic copolymer (A-1)>
A four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet was charged with 40 parts of ethyl acetate, 1.7 parts of IPA, and 15 parts of macromonomer (a-1) as the charged solvent. The temperature was raised to 85 ° C. under gas flow. After reaching 85 ° C., a mixture comprising 20 parts of ethyl acetate, 81 parts of n-butyl acrylate, 4 parts of acrylic acid and 0.04 part of benzoyl peroxide was added dropwise over 4 hours. After holding for 1 hour after the completion of dropping, a mixture of 0.5 part of “Perocta O” and 10 parts of ethyl acetate was added, and after holding for 2 hours, “Irganox 1010” (product of BASF Corporation) was used as an antioxidant. Name) After adding 0.5 part, after adding ethyl acetate so that solid content might be 50%, it cooled to room temperature and obtained the (meth) acrylic-type copolymer (A-1).

[Production Examples 2 to 8]
<Production of (meth) acrylic copolymers (A-2) to (A-8)>
(Meth) acrylic copolymer in the same manner as in Production Example 1 except that the composition of the monomer mixture used (macromonomer (a) and vinyl monomer (b)) and the initial charge solvent were changed to Table 2. (A-2) to (A-8) were obtained.
In addition, (A-7) is an example in which the macromonomer (a) was not used.

MMA: methyl methacrylate n-BA: n-butyl acrylate 2-EHA: 2-ethylhexyl acrylate AA: 2-HEMA acrylate: 2-hydroxyethyl methacrylate

[Example 1]
The (meth) acrylic copolymer (A-1) produced in Production Example 1 was applied to one side of a polyethylene terephthalate film (PET film) so that the thickness after drying was 50 μm, and then at 100 ° C. for 30 minutes. The sealing material was obtained by making it dry. Subsequently, the release layer side of the polyethylene terephthalate film (PET film, thickness 50 μm) subjected to the release treatment was bonded to the sealant, and this was used as a transparent sealant for organic EL devices. This organic EL element sealing material was evaluated by the following methods. The results are shown in Table 23.

[Examples 2 to 6, Comparative Examples 1 and 2]
Using the (meth) acrylic copolymer (A) produced in Production Examples 2 to 8, a sealing material for organic EL elements was obtained in the same manner as in Example 1.

[Examples 7 to 10]
The (meth) acrylic copolymers (A-1 to A-3, A-6) prepared in Production Examples 1 to 3 and 6 were mixed with the monomers and photoinitiators shown in Table 4, and a 50 μm PET film. After coating to a thickness of 50 μm after drying, an adhesive layer was formed by drying at 100 ° C. for 30 minutes. Furthermore, the peeling layer side of the 50 μm PET film subjected to the peeling treatment was bonded to the adhesive layer side, and UV irradiation was performed using a 2P curing device with a high-pressure mercury lamp, an irradiation intensity of 200 mW / cm ² , and an irradiation amount of 1000 mJ / cm ^2. Then, the pressure-sensitive adhesive layer was cross-linked to obtain an organic EL element sealing material.

[Examples 11 and 12]
The (meth) acrylic copolymer (A-5) produced in Production Example 5 was mixed with the crosslinking agent shown in Table 4 and applied to a 50 μm PET film so that the thickness after drying was 50 μm. An adhesive layer was formed by drying at 100 ° C. for 30 minutes. Further, the release layer side of a 50 μm PET film subjected to the release treatment was bonded to the pressure-sensitive adhesive layer side, and after curing at 40 ° C. for 3 days, an organic EL device sealing material was obtained.

Examples 1 to 12 and Comparative Examples 1 and 2 were evaluated by the following methods.
The results are shown in Table 3 and Table 4.

(Evaluation method)
It measured using the molecular weight gel permeation chromatography (GPC) (Tosoh Corporation HLC-8120) of the (meth) acrylic-type copolymer (A) . After adjusting 0.3% by mass of the tetrahydrofuran solution of the acrylic copolymer (A), 20 μl of the above solution was injected into a device equipped with a Tosoh column (TSKgel SuperHM-H * 4, TSKguardcolumn SuperH-H). , Flow rate: 0.06 ml / min, eluent: tetrahydrofuran (stabilizer BHT), column temperature: measured at 40 ° C., and weight average molecular weight (Mw) was calculated in terms of standard polystyrene.

In accordance with the holding power test JISZ0237, the release film of the sealing material prepared by the above method is peeled off, and a 30 mm × 100 mm SUS plate is used with a 2 kg hand roller so that the bonding surface is 20 × 20 mm. Pasted together. After curing at 40 ° C. for 30 minutes, a 0.5 kg weight was attached to the end of the PET film, and the holding time was measured in a constant temperature layer at 40 ° C. Holding power was determined according to the following criteria.
Holding time 30 minutes or more: ◎
5 minutes or more and 30 minutes or less: ○
Within 5 minutes: ×

Adhesion test In accordance with JISZ0237, the peel strength Y for a glass substrate with an ITO film is measured at a peel angle of 180 ° and a tensile speed of 60 mm / min. The adhesive strength was determined according to the following criteria.
Y ≧ 3N / 25mm: ○
Y <3N / 25mm: ×

Sealability When the determination by the holding force test is “◯” and the determination by the adhesion test is “O”, the space generated inside the display panel is closely adhered without any gap, and the state can be maintained. Therefore, “◯” was given as being excellent in sealing properties, and “X” was given as being otherwise inferior in sealing properties.

Image Visibility The printed matter was brought into close contact with the organic EL element sealing material prepared by the above-described method, and the visibility of the printed matter was visually determined. The case where it was good was “◯”, and the case where it was bad was “x”.

IRGAQUR184: Ciba brand name TPA-100: Asahi Kasei brand name Coronate L: Nippon Polyurethane brand name

In Examples 1 to 6, good sealing properties were shown and the visibility was excellent.
On the other hand, Comparative Example 1 uses a (meth) acrylic copolymer (A-7) that does not use the macromonomer (a), and has poor sealing properties.
Moreover, the comparative example 2 used the (meth) acrylic-type copolymer (A-8) which used the thing whose number average molecular weights of the macromonomer (a) are 7000, and was inferior in sealing property.
Examples 7 to 12 are examples in which the pressure-sensitive adhesive layer was cross-linked, but in this case as well, it had good stopping properties and was excellent in visibility.

The sealing material for organic EL elements of the present invention is suitable for EL display panels for mobile phones, personal digital assistants, desktop computers, notebook computers, televisions, in-vehicle information devices, watches, and other various display devices. Can be used.

Claims (2)

  A weight average molecular weight of 10,000 to 1,000,000 obtained by polymerizing a monomer mixture containing a macromonomer (a) having a number average molecular weight of 500 or more and less than 6000 and a vinyl monomer (b) (meta ) A sealing material for organic EL, which uses an acrylic copolymer (A). The organic EL sealing material according to claim 1, wherein the macromonomer (a) is represented by the following formula (2).
(In the formula (2), n is a natural number .R and ^R 1 to R ⁿ of 4-5999 are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. Alkyl The group, cycloalkyl group, aryl group or heterocyclic group may have a substituent, and X ^{1 to} X ⁿ are each independently a hydrogen atom or a methyl group.)