JP7091707B2 - Encapsulation composition - Google Patents

Description

The present invention relates to a sealing composition, and makes a sealing composition particularly suitable for sealing a flexible electronic device.

Conventionally, glass substrates have been mainly used in the field of electronic devices such as flat panel displays and electronic paper, but glass substrates are heavy and fragile, and there is a problem that their strength decreases when they are made lighter or thinner. For this reason, in recent years, flexible electronic devices in which the substrate has been replaced with a plastic substrate have been attracting attention. Recently, even in an organic EL device using an organic EL (Electroluminescence) element as a light emitting element, a plastic substrate has been used for weight reduction and flexibility.

On the other hand, an organic EL element is extremely sensitive to moisture, and when the light emitting material deteriorates due to the influence of moisture, the brightness decreases. Therefore, in general, an organic EL device or an organic device is used to block the inside of the element from moisture in the outside air. The entire surface of the EL display panel is sealed with a sealing layer made of a resin composition. This sealing layer is required to have not only moisture permeability resistance for blocking the organic EL element from moisture but also high transparency for transmitting light emitted from the organic EL element. For example, Patent Document 1 describes styrene-isobutylene. A sealing resin composition containing a modified resin (particularly, a maleic anhydride-modified styrene-isobutylene-styrene block copolymer) and a tackifier resin has been proposed. However, when an organic EL device or an organic EL display panel using a plastic substrate is sealed with a conventional sealing resin composition, the organic EL device or the organic EL display panel is stored in a high temperature and high humidity environment. , There is a problem that bubbles are generated at the interface between the sealing layer and the plastic substrate.

International Publication No. 2013/108731 Pamphlet

In view of the above circumstances, according to the present invention, even if the flexible electronic device after sealing is stored in a high temperature and high humidity environment, air bubbles are less likely to be generated at the interface with the plastic substrate, and the sealing also has high transparency. It is an object of the present invention to provide a sealing composition capable of forming a stop layer.

As a result of diligent research to achieve the above object, the present inventors have found that the sealing layer formed mainly of a resin having a urethane bond is less likely to generate bubbles at the interface with the plastic substrate. The present invention has been completed by further research based on the findings and such findings.

That is, the present invention has the following features.
[1] A composition for encapsulating a flexible electronic device, comprising (A1) a resin having a urethane bond and / or (A2) a compound for producing a resin having a urethane bond.
[2] The resin having a urethane bond (A1) is a polyurethane resin having at least a polyester polyurethane skeleton, and the resin-forming compound having a urethane bond (A2) contains at least a polyol containing a polyester polyol and a polyfunctional isocyanate. , The composition according to the above [1].
[3] The composition according to the above [1] or [2], further comprising (B) a hygroscopic filler.
[4] The composition according to any one of the above [1] to [3], wherein the flexible electronic device is a flexible organic EL device.
[5] A flexible electronic device encapsulation sheet comprising a support and a layer of the composition according to any one of the above [1] to [3] formed on the support.
[6] The sheet according to the above [5], wherein the flexible electronic device is a flexible organic EL device.
[7] The electronic element formed on the plastic substrate is sealed with a composition layer containing a resin having a urethane bond formed by the composition according to any one of the above [1] to [3]. Is a flexible electronic device.
[8] The flexible electronic device according to the above [7], wherein the electronic element formed on the plastic substrate is an organic EL element, and the flexible electronic device is a flexible organic EL device.

According to the sealing composition of the present invention, it is possible to form a sealing layer that is less likely to generate bubbles at the interface with the plastic substrate and also has high transparency.

The sealing composition of the present invention is for sealing a flexible electronic device, and is for producing a resin having a urethane bond and / or a resin-forming compound having a urethane bond (that is, a resin having a urethane bond). The main feature is that it contains (a compound of). For example, it is preferable to add a hygroscopic filler to the sealing layer of an organic EL device from the viewpoint of suppressing water vapor permeability, but such a sealing layer maintains high transparency and low haze while maintaining a plastic substrate. It is difficult to suppress the generation of bubbles at the interface with. However, the sealing layer, which is a composition layer containing a resin having a urethane bond formed by the sealing composition of the present invention, maintains high transparency and low haze even if it contains a hygroscopic filler. Moreover, it is possible to suppress the generation of bubbles at the interface with the plastic substrate. Hereinafter, the constituent components of the sealing composition of the present invention will be described in detail.

[(A1) Resin having urethane bond and / or (A2) Compound for resin production having urethane bond]
The sealing composition of the present invention (hereinafter, also simply referred to as “composition”) contains (A1) a resin having a urethane bond and / or (A2) a resin-forming compound having a urethane bond. Hereinafter, "(A1) a resin having a urethane bond and / or (A2) a compound for producing a resin having a urethane bond" is also collectively referred to as "(A) component".

Examples of the resin having the (A1) urethane bond include polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin and the like, and are selected from polyester polyurethane skeleton, polyether polyurethane skeleton and polycarbonate polyurethane skeleton. It may be a resin containing two or more kinds of polyurethane skeletons. Among them, a polyurethane resin having at least a polyester polyurethane skeleton is preferable, and a polyurethane resin whose main skeleton is a polyester polyurethane skeleton is preferable from the viewpoint of realizing a sealing layer capable of suppressing the generation of bubbles at the interface with a plastic substrate at a higher level. Is more preferable. That is, a polyurethane resin in which the polyester polyurethane skeleton is 60 to 100% by mass of the whole is preferable, a polyurethane resin in which the polyester polyurethane skeleton is 70 to 100% by mass of the whole is more preferable, and the polyester polyurethane skeleton is 80 to 100% by mass of the whole. The polyurethane resin is even more preferable, and the polyurethane resin in which the polyester polyurethane skeleton is 90 to 100% by mass of the whole is most preferable.

The (A2) resin-forming compound having a urethane bond is a compound for producing (A1) a resin having a urethane bond, and includes (A21) a polyol and (A22) a polyfunctional isocyanate.

That is, the composition of the present invention is
(I) (A1) A mode containing a resin having a urethane bond,
(Ii) An embodiment containing (A2) a resin-forming compound having a urethane bond ((A21) polyol and (A22) polyfunctional isocyanate), or
(Iii) Any of the embodiments containing (A1) a resin having a urethane bond and (A2) a resin-forming compound having a urethane bond ((A21) polyol and (A22) polyfunctional isocyanate) may be used. From the viewpoint of realizing the object of the invention at a higher level, the embodiment (iii) or (iii) is preferable. When the composition of the present invention is in the embodiment (ii) or (iii), particularly in the embodiment (ii), the (A21) polyol is arranged in the layer of the composition disposed on the plastic substrate of the flexible electronic device. (A22) By proceeding with the urethanization reaction (reaction of forming a resin having a urethane bond) with the polyfunctional isocyanate, the adhesion to the plastic substrate is better, and air bubbles are less likely to be generated at the interface with the plastic substrate. A stop layer can be formed.

As will be described later, the encapsulation of the electronic element of the flexible electronic device by the encapsulation composition of the present invention is also referred to as an electronic element formed on the plastic substrate of the flexible electronic device (hereinafter, also referred to as “electronic element on the plastic substrate”). An embodiment in which the composition is directly applied to a required portion of a plastic substrate so as to cover (abbreviated as), and the coating film (layer of the composition) is cured to form a sealing layer containing a resin having a urethane bond. Alternatively, a sealing sheet having a layer of the composition formed on the support is prepared, and the sealing sheet is laminated on a necessary place on a plastic substrate of a flexible electronic device to form a layer of the composition. Is transferred onto a plastic substrate, and then the layer of the composition is cured to form a sealing layer containing a resin having a urethane bond, or the sealing sheet is used at a required place on the plastic substrate of a flexible electronic device. The layer of the composition is cured as it is to form a sealing layer containing a resin having a urethane bond.

<(A21) Polyol>
As described above, the resin having (A1) urethane bond is preferably at least a polyurethane resin having a polyester polyurethane skeleton, and therefore, the (A21) polyol in the resin-forming compound having (A2) urethane bond (hereinafter, "(A21)). The "component") "preferably contains at least a polyester polyol, and more preferably a polyester polyol alone or an embodiment containing a polyester polyol and a polyether polyol and / or a polycarbonate polyol.

(Polyester polyol)
Examples of the polyester polyol include a polyester diol obtained by reacting a dihydric alcohol with a dibasic acid. The dihydric alcohol in the polyester diol may be any one or more selected from an aliphatic diol, an alicyclic diol and an aromatic diol. Preferably, the aliphatic diol alone or a combination of the aliphatic diol and the alicyclic diol or the aromatic diol. The aliphatic diol is preferably an aliphatic diol having 2 to 26 carbon atoms, for example, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,6-hexanediol, neo. Examples thereof include pentyl glycol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol and the like. The alicyclic diol is preferably an alicyclic diol having 6 to 26 carbon atoms, and is, for example, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, or 2-methyl-. Cyclohexanediols such as 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, cyclohexanedimethanol such as 1,4-cyclohexanedimethanol, 2,3-norbornanedimethanol, Norbornane dimethanols such as 2,5-norbornane dimethanol, tricyclodecane dimethanol, pentacyclopentadecane dimethanol, 1,3-adamantan diol, 2,2-adamantan diol, decalin dimethanol, 2,2,4 Examples include 4-tetramethyl-1,3-cyclobutanediol and 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane. Be done. Examples of the aromatic diol include bisphenol A, bisphenol A alkylene oxide adduct, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 9,9'-bis (4-hydroxyphenyl) fluorene, 2, Examples thereof include 2'bis (4'-β-hydroxyethoxyphenyl) propane. In addition, one kind or two or more kinds of aliphatic diols, alicyclic diols and aromatic diols can be used respectively.

The dihydric alcohol preferably contains an aliphatic diol having 2 to 20 carbon atoms and / or an alicyclic diol having 3 to 20 carbon atoms, and more preferably a fat having 3 to 8 carbon atoms. It is an embodiment containing a group diol, and particularly preferably an embodiment containing 3-methyl-1,5-pentanediol and 1,3-cyclohexanediol.

The dibasic acid for forming the polyester diol may be any one or more selected from an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid and an aromatic dicarboxylic acid. Preferably, the aliphatic dicarboxylic acid alone or a combination of the aliphatic dicarboxylic acid and the alicyclic dicarboxylic acid or the aromatic dicarboxylic acid. As the aliphatic dicarboxylic acid, an aliphatic dicarboxylic acid having 2 to 26 carbon atoms is preferable. Examples thereof include diionic acid, pimelli acid, azelaic acid, methylmalonic acid and ethylmalonic acid. As the alicyclic dicarboxylic acid, an alicyclic dicarboxylic acid having 5 to 26 carbon atoms is preferable, and examples thereof include adamantandicarboxylic acid, norbornnedicarboxylic acid, cyclohexanedicarboxylic acid, and decalindicarboxylic acid. As the aromatic dicarboxylic acid, an aromatic dicarboxylic acid having 8 to 26 carbon atoms is preferable, and for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenylether dicarboxylic acid, 5-sodium sulfoisophthalic acid, phenylendandicarboxylic acid, anthracendicarboxylic acid, phenanthrangecarboxylic acid Acids, 9,9'-bis (4-carboxyphenyl) fluorenic acid and the like can be mentioned.

As the dibasic acid, one kind or two or more kinds of compounds are used. Among them, an aliphatic dicarboxylic acid having 2 to 20 carbon atoms and / or an alicyclic dicarboxylic acid having 3 to 20 carbon atoms is preferable, and an aliphatic dicarboxylic acid having 3 to 10 carbon atoms is particularly preferable. Preferred are adipic acid, sebacic acid and the like.

Commercially available products can be used as the polyester polyol. For example, Polyester SNT (manufactured by Nippon Synthetic Chemical Co., Ltd., number average molecular weight 10000, hydroxyl value 8 mgKOH / g), Polyester S0091 (manufactured by Nippon Synthetic Chemical Co., Ltd., number average molecular weight 21000, hydroxyl value 4.5 mgKOH / g), Clare polyol. P-2050 (manufactured by Kuraray, number average molecular weight 2000, hydroxyl value 56 mgKOH / g), Kurare polyol PMPA1500 (manufactured by Kurare, number average molecular weight 1500, polyester polyol consisting of adipic acid and 3-methyl-1,5-pentanediol) ), Claret polyol PMPA2000 (manufactured by Claret, number average molecular weight 2000, polyester polyol composed of adipic acid and 3-methyl-1,5-pentanediol), Claret polyol O-2010 (manufactured by Claret, number average molecular weight 7000, 1) , 9-Nonandiol-containing crystalline polyester polyol), Polylite OD-X-2251 (manufactured by DIC, number average molecular weight 2000, hydroxyl value 56 mgKOH / g), Polylite OD-X-2523 (manufactured by DIC, number average molecular weight 3500) , Hydroxyl value 32 mgKOH / g), Polylite OD-X-2547 (manufactured by DIC, number average molecular weight 4500, hydroxyl value 25 mgKOH / g) and the like.

(Polyether polyol)
As the polyether polyol, for example, a polyether diol obtained by ring-opening polymerization of an ion-polymerizable cyclic compound such as ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, tetrahydrofuran, 2-methyltetrahydrofuran and 3-methyltetrahydrofuran. Can be mentioned. At this time, a copolymer composed of two or more kinds of ion-polymerizable cyclic compounds may be used. In this case, the polymerization mode of each structural unit in the diol is not particularly limited, and random polymerization, block polymerization, alternating polymerization, and grafting are not particularly limited. It may be any of polymerization. Examples of polyether diols obtained by ring-opening polymerization of one of the above ion-polymerizable cyclic compounds include polyethylene glycol, polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polyhexamethylene glycol, and polyhepta. Examples thereof include diols such as methylene glycol and polydecamethylene glycol. Specific examples of the polyether diol obtained by ring-opening and copolymerizing two or more of the above ion-polymerizable cyclic compounds include, for example, tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, and tetrahydrofuran and 3-methyltetrahydrofuran. Binary copolymers obtained from a combination of tetrahydrofuran and ethylene oxide, propylene oxide and ethylene oxide, butene-1-oxide and ethylene oxide; ternary polymers obtained from a combination of tetrahydrofuran, butene-1-oxide and ethylene oxide and the like. Can be done.

(Polycarbonate polyol)
Examples of the polycarbonate polyol include a diol compound represented by the following formula (1) (hereinafter, also abbreviated as “diol compound of the formula (1)”).

[In the formula, n + 1 Rs are independently divalent aliphatic hydrocarbon groups, or formula (2):

[In the formula, the two R's each independently represent a single bond or an alkanediyl group having 1 to 3 carbon atoms. ]
Represents a divalent hydrocarbon group having an alicyclic structure represented by, and n is a number determined so that the number average molecular weight of the compound is 500 to 1,000,000. "

The n + 1 Rs in the formula (1) may be the same or different, and each is preferably a divalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, and each has a divalent value having 1 to 12 carbon atoms. Examples of the aliphatic hydrocarbon group include-(CH ₂ ) _m- (m in the formula is 1 to 12 (preferably 3 to 12, more preferably 5 to 9)), -CH ₂ CH (CH ₃ ). CH _2- , -CH ₂ CH ₂ C (CH ₃ ) HCH ₂ CH _2- , -CH ₂ C (CH ₃ ) H (CH ₂ ) _6- and the like can be mentioned.

Preferred specific examples of R in the formula (1) include-(CH ₂ ) ₆ -,-(CH ₂ ) _9- , -CH ₂ C (CH ₃ ) H (CH ₂ ) _6- , and the like.

Examples of the alkanediyl group having 1 to 3 carbon atoms represented by R'in the formula (2) include -CH ₂ -,-(CH ₂ ) ₂ -,-(CH ₂ ) _3- , and -CH ₂ . -CH (CH ₃ )-etc.

As the diol compound of the above formula (1), a commercially available product can be used, and as the commercially available product, for example, Duranol T6002 (in the formula (1), R is-(CH ₂ ) _6- , and the number average molecular weight is 2000 compounds), Duranol T5650E (in formula (1), R is-(CH ₂ ) _5- and-(CH ₂ ) _6- (molar ratio 1: 1), and the number average molecular weight is 500. ), Duranol T5652 (in formula (1), R is-(CH ₂ ) _5- and-(CH ₂ ) _6- (molar ratio 1: 1), number average molecular weight is 2000), G3452 ( In formula (1), R is-(CH ₂ ) _3- and-CH ₂ CH (CH ₃ ) CH _2- (molar ratio 1: 1) and the number average molecular weight is 2000) (above, Asahi Kasei (Manufactured by Chemicals), UH-200 (in formula (1), R is-(CH ₂ ) _6- , a compound having a number average molecular weight of 2000), UH-300 (in formula (1), R is-( CH ₂ ) _6- (compound with a number average molecular weight of 3000), UHC50-200 (in formula (1), R is-(CH ₂ ) _6- and-((CH ₂ ) ₅ CO ₂ ) _m (CH) ₂ ) _6- (a compound having a molar ratio of 1: 1) and a number average molecular weight of 2000), UHC50-100 (in formula (1), R is-(CH ₂ ) _6- and-((CH ₂ )). ₅ CO ₂ ) _m (CH ₂ ) _6- (a compound having a molar ratio of 1: 1) and a number average molecular weight of 1000), UC-100 (in formula (1), R is R in the above formula (2)). 'Is -CH _2- , a compound having a number average molecular weight of 1000), (all manufactured by Ube Kosan Co., Ltd.), Claret polyol C-1065N (in formula (1), R is-(CH ₂ ) ₉ -and- CH ₂ C (CH ₃ ) H (CH ₂ ) _6- (a compound having a molar ratio of 65:35 and a number average molecular weight of 1000), Clare polyol C-2065N (in formula (1), R is-(1). CH ₂ ) ₉ -and-CH ₂ C (CH ₃ ) H (CH ₂ ) _6- (a compound having a molar ratio of 65:35 and a number average molecular weight of 2000), Clare polyol C-2015N (formula (1) ), R is − (CH ₂ ) ₉ − and −CH ₂ C (CH ₃ ) H (CH ₂ ) ₆ − (molar ratio is 15:85), and the number average molecular weight is 2000 compounds), Claret polyol C-2090 (in formula (1), R is -CH ₂ CH ₂ C (CH ₃ ) HCH ₂ CH _2- and-(CH ₂ ) _6- (molar ratio 9: 1) (A compound having a number average molecular weight of 2000), Claret polyol C-2050 (in formula (1), R is -CH ₂ CH ₂ C (CH ₃ ) HCH ₂ CH _2- and-(CH ₂ ) _6- ( A compound having a molar ratio of 1: 1) and a number average molecular weight of 2000) (all manufactured by Kuraray Co., Ltd.) and the like can be mentioned.

The number average molecular weight of the (A21) polyol in the present invention is preferably 1000 to 100,000, more preferably 1000 to 30,000, and particularly preferably 2000 to 2500 from the viewpoint of realizing the object of the present invention at a higher level.

Further, from the viewpoint of realizing the object of the present invention at a higher level, the polyol (A21) has (a) a low molecular weight component having a number average molecular weight of 1000 or more and less than 5000, and (b) a number average molecular weight of 5000 or more and 15000. It is preferable to contain three components having a medium molecular weight component of less than (c) and a high molecular weight component having a number average molecular weight of 15,000 or more and less than 30,000.

The "number average molecular weight" in the present specification is measured by a gel permeation chromatography (GPC) method (polystyrene conversion). For the number average molecular weight by the GPC method, use LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, Shodex K-800P / K-804L / K-804L manufactured by Showa Denko Corporation as a column, and toluene as a mobile phase. It can be measured at a column temperature of 40 ° C. and calculated using a standard polystyrene calibration curve.

From the viewpoint of realizing the object of the present invention at a higher level, the hydroxyl value of the (A21) polyol is preferably in the range of 4 to 60 mgKOH / g. In particular, (a) the hydroxyl value of the low molecular weight component is in the range of more than 20 mgKOH / g and 60 mgKOH / g or less, and (b) the hydroxyl value of the medium molecular weight component and (c) the high molecular weight component is 4 to 20 mgKOH / g. It is more preferably in the range, (a) the hydroxyl value of the low molecular weight component is in the range of 50 to 60 mgKOH / g, and (b) the hydroxyl value of the medium molecular weight component and (c) the hydroxyl value of the high molecular weight component is 4 to 10 mgKOH / g. It is particularly preferable that it is in the range of. The hydroxyl value in the present specification is measured according to JIS K 1557-1.

Further, from the viewpoint of realizing the object of the present invention at a higher level, 60 to 100% by mass of the (A21) polyol is composed of a polyester polyol, and 0 to 40% by mass is a polyether polyol and / or a polycarbonate polyol. It is preferably composed of 80 to 100% by mass of polyester polyol, more preferably 0 to 20% by mass composed of a polyether polyol and / or a polycarbonate polyol, and 90 to 100% by mass of the total polyester polyol. It is even more preferably made of 0 to 10% by mass of a polyether polyol and / or a polycarbonate polyol, and particularly preferably 100% by mass of the whole.

<(A22) Polyfunctional isocyanate>
The (A22) polyfunctional isocyanate is not particularly limited as long as it is a compound having at least two or more isocyanate groups in the molecule that react with the hydroxyl group of the (A21) polyol. Specific examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

Examples of the aliphatic polyisocyanates include 1,2-ethylene diisocyanate, 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, and tetramethylene diisocyanate such as 1,4-tetramethylene diisocyanate, 1, 2-Hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexamethylene diisocyanate such as 2,5-hexamethylene diisocyanate , 2-Methyl-1,5-pentanediisocyanate, 3-methyl-1,5-pentanediisocyanate, lysine diisocyanate and the like. It can use one or more.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate, cyclohexanediisocyanate such as 1,2-cyclohexanediisocyanate, 1,3-cyclohexanediisocyanate, and 1,4-cyclohexanediisocyanate, 1,2-cyclopentane diisocyanate, and 1, , Cyclopentane diisocyanate such as 3-cyclopentane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate, 4,4'-disichexylmethane diisocyanate and the like. .. It can use one or more.

Examples of the aromatic polyisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate. 4,4'-Diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate 4,4'-Diphenylpropane diisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate , Xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate and the like. It can use one or more.

Further, as the above-mentioned aliphatic polyisocyanates, alicyclic polyisocyanates and aromatic polyisocyanates, a dimer or a trimer of the exemplified compound can be used in addition to the exemplified compound, respectively. Specifically, trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Coronate L), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product) Name coronate HL), isocyanate adducts such as isocyanurates of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Coronate HX), trimethylolpropane adduct of xylylene diisocyanate (manufactured by Mitsui Chemicals Co., Ltd., trade name D110N), Examples thereof include a trimethylolpropane adduct of hexamethylene diisocyanate (manufactured by Mitsui Kagaku Co., Ltd., trade name D160N).

(A22) As the polyfunctional isocyanate, one or more selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates and aromatic polyisocyanates can be used. Further, the (A22) polyfunctional isocyanate is preferably one having three or more isocyanate groups in one molecule. Further, the (A22) polyfunctional isocyanate preferably has an isocyanate group (—NCO) content in the range of 3 to 40% by mass, and more preferably in the range of 5 to 20% by mass.

In the composition of the present invention, the mixing ratio of the (A21) polyol and the (A22) polyfunctional isocyanate is such that the hydroxyl group (-OH) and the (A22) polyfunctional isocyanate contained in the (A21) polyol are used from the viewpoint of reducing unreacted substances. The equivalent ratio (NCO / OH) of the isocyanate group (-NCO) to have is preferably 0.2 / 1 to 2/1, more preferably 0.4 / 1 to 1.5 / 1, and particularly preferably 0.6. The amount is 1/1 to 1.2 / 1.

<(A23) A compound having two hydroxyl groups and one carboxyl group in one molecule>
The composition of the present invention includes (A21) a polyol and (A22) a polyfunctional isocyanate, and (A23) a compound having two hydroxyl groups and one carboxyl group in one molecule (hereinafter, "dihydroxycarboxylic acid compound"). It is possible to mix (referred to as).

Examples of the (A23) dihydroxycarboxylic acid compound include dihydroxyfumaric acid, dihydroxymaleic acid, 2,2-bis (hydroxymethyl) ethanoic acid (also known as dimethylolacetic acid), and 2,3-dihydroxypropanoic acid (also known as glyceric acid). ), 2,2-Bis (hydroxymethyl) propanoic acid (also known as 2,2-dimethylolpropionic acid), 3,3-bis (hydroxymethyl) propanoic acid (also known as 3,3-dimethylolpropionic acid), 2,3-Dihydroxy-2-methylpropanoic acid, 2,2-bis (hydroxymethyl) butanoic acid (also known as dimethylol fatty acid), 2,2-dihydroxybutanoic acid (also known as 2,2-dimethylol butanoic acid), 2,3-Dihydroxybutanoic acid, 2,4-dihydroxybutanoic acid (also known as 3-deoxytetronic acid), 3,4-dihydroxybutanoic acid, 2,4-dihydroxy-3,3-dimethylbutanoic acid, 2,3 -Dihydroxy-2-methylbutanoic acid, 2,3-dihydroxy-2-ethylbutanoic acid, 2,3-dihydroxy-2-isopropylbutanoic acid, 2,3-dihydroxy-2-butylbutanoic acid, (R) -2,4- Dihydroxy-3,3-dimethylbutanoic acid (also known as vantoic acid), 2,3-dihydroxybutanediic acid (also known as tartrate), 2,2-bis (hydroxymethyl) pentanoic acid (also known as dimethylol valeric acid), 3 , 5-Dihydroxy-3-methylpentanoic acid (also known as mevalonic acid), 2,2-bis (hydroxymethyl) hexanoic acid (also known as dimethylolcaproic acid), 2,2-bis (hydroxymethyl) heptanic acid (also known as) , Dimethylol enanthic acid), 3,5-dihydroxyheptanoic acid, 2,2-bis (hydroxymethyl) octanoic acid (also known as dimethylolcapric acid), 2,2-bis (hydroxymethyl) nonanoic acid (also known as dihydroxymethyl) nonanoic acid. Methylolverargonic acid), 2,2-bis (hydroxymethyl) decanoic acid (also known as dimethylolcapric acid), 2,2-bis (hydroxymethyl) dodecanoic acid (also known as dimethylollauric acid), 2,2- Bis (hydroxymethyl) tetradecanoic acid (also known as dimethyrol myristic acid), 2,2-bis (hydroxymethyl) pentadecanoic acid, 2,2-bis (hydroxymethyl) hexadecanoic acid (also known as dimethylol palmitic acid), 2, 2-bis (hydroxymethyl) heptadecanoic acid (also known as dimethylolmargalic acid), 2,2-bis (hydroxymethyl) octa Aliphatic dihydroxycarboxylic acids such as decanoic acid (also known as dimethylol stearate), dimethylol oleic acid, dimethylol linoleic acid, dimethylol linolenic acid, dimethylol aracodonic acid, dimethylol docosahexaenoic acid, and dimethylol eicosapentaenoic acid. 2,3-Dihydroxybenzoic acid (also known as o-pyrocatechuic acid), 2,4-dihydroxybenzoic acid (also known as β-resorcinic acid), 2,5-dihydroxybenzoic acid (also known as gentidic acid), 2,6 -Dihydroxybenzoic acid (also known as γ-resorcinic acid), 3,4-dihydroxybenzoic acid (also known as protocatechuic acid), 3,5-dihydroxybenzoic acid (also known as α-resorcinic acid), 2,6-dihydroxy-4 -Methyl benzoic acid, 2,4-dihydroxy-6-methyl benzoic acid (also known as o-orceric acid), 3,5-dihydroxy-4-methyl benzoic acid, 2,4-dihydroxy-3,6-dimethyl benzoic acid , 2,3-Dihydroxy-4-methoxybenzoic acid, 3,4-dihydroxy-5-methoxybenzoic acid, 2,4-di (hydroxymethyl) benzoic acid, 3,4-di (hydroxymethyl) benzoic acid, 4 -Bromo-3,5-dihydroxybenzoic acid, 5-bromo-2,4-dihydroxybenzoic acid, 3-chloro-2,6-dihydroxybenzoic acid, 5-chloro-2,4-dihydroxybenzoic acid, hydroxy (4) -Hydroxy-3-methoxyphenyl) acetic acid (also known as vanylmandelic acid), D, L-3,4-dihydroxymandelic acid, 2,5-dihydroxyphenylacetic acid (also known as homogentidic acid), 3,4-dihydroxyphenylacetic acid (also known as homogentidic acid). Also known as homoprotocatechuic acid), 3,4- (methylenedioxy) phenylacetic acid, 3- (3,4-dihydroxyphenyl) propanoic acid (also known as hydrocaffeic acid), 3- (2,4-dihydroxyphenyl) acrylic acid (Also known as Umberic acid), 3- (3,4-dihydroxyphenyl) acrylic acid (also known as caffeic acid), 4,4'-bis (p-hydroxyphenyl) pentanoic acid, 3- (3,4-methylenedi) Oxyphenyl) propionic acid, 2,2-bis (hydroxymethyl) butyric acid, 2,4-dihydroxy cinnamic acid, 2,5-dihydroxy cinnamic acid, cinnamyl-3,4-dihydroxy-α-cyano cinnamic acid, 2-bromo -4,5-methylenedioxy cinnamic acid, 3,4-methylenedioxy cinnamic acid, 4,5-methylenedioxy-2-nitrocineric acid, 2,6-dihydroxyi Sonicotinic acid, DL-3,4-dihydroxymandelic acid, 1,4-dihydroxy-2-naphthalenecarboxylic acid, 3,5-dihydroxy-2-naphthalenecarboxylic acid, 3,7-dihydroxy-2-naphthalenecarboxylic acid, 4 , 8-Dihydroxyquinoline-2-carboxylic acid (also known as xanthurenic acid) 3- (3,4-dihydroxyphenyl) propionic acid, 2,4-dihydroxypyrimidine-5-carboxylic acid, 2,6-dihydroxypyridine-4- Carboxylic acid (also known as citradic acid), 2,4-dihydroxythiazole-5-acetic acid, 2- (1-thienyl) ethyl-3,4-dihydroxybenzidenecyanoacetic acid, dipropionic acid-6-estradiol, 2,5- Examples thereof include aromatic rings such as dihydroxy-1,4-benzenediacetic acid, (2R, 3R) -2,3-dihydroxy-3- (phenylcarbamoyl) propionic acid, and heterocyclic dihydroxycarboxylic acids.

Since the (A23) dihydroxycarboxylic acid compound has two hydroxyl groups, it is double-added (urethanized reaction) with (A22) polyfunctional isocyanate in the same manner as the (A21) polyol to produce polyurethane. Then, one carboxyl group of the (A23) dihydroxycarboxylic acid compound becomes a carboxyl group of the side chain of polyurethane.

It is preferable that the two hydroxyl groups in the dihydroxycarboxylic acid compound are both primary in that they are rich in activity during the urethanization reaction. On the other hand, when the carboxyl group functions as a reaction component during the urethanization reaction, it tends to gel during the reaction, and even if a polyurethane resin is obtained without gelling, it tends to partially aggregate. Therefore, the carboxyl group is preferably secondary or tertiary so as not to function as a reaction component of the urethanization reaction.

By using the (A23) dihydroxycarboxylic acid compound instead of a part of the (A21) polyol, it becomes easy to produce a resin having a urethane bond, which is difficult to partially aggregate and has a high uniformity.

The content of the component (A) in the composition of the present invention is not particularly limited, but from the viewpoint of adhesion between the sealing layer and the plastic substrate, 85% by mass per 100% by mass of the total non-volatile content in the composition. The following is preferable, 80% by mass or less is preferable, 75% by mass or less is more preferable, and 70% by mass or less is further preferable. Further, from the viewpoint of imparting flexibility to the sealing layer, 30% by mass or more is preferable, 35% by mass or more is more preferable, and 40% by mass or more is further preferable, per 100% by mass of the total non-volatile content in the composition. ..

<(B) Hygroscopic filler>
In the composition of the present invention, a hygroscopic filler (hereinafter, also abbreviated as "component (B)") ") can be added to the sealing layer in order to impart higher water vapor permeability. The hygroscopic filler (B) is not particularly limited as long as it is a filler having an ability to absorb water, but is preferably a hygroscopic metal oxide. A hygroscopic metal oxide means a metal oxide having an ability to absorb water and chemically reacting with the absorbed water to become a hydroxide. Specific examples thereof include calcium oxide, magnesium oxide, strontium oxide, aluminum oxide, barium oxide, unfired hydrotalcite, semi-fired hydrotalcite, fired hydrotalcite, and fired dolomite. Of these, semi-calcined hydrotalcite and calcined hydrotalcite are preferable from the viewpoint of hygroscopicity.

Hydrotalcite can be classified into uncalcined hydrotalcite, semi-calcined hydrotalcite, and calcined hydrotalcite.

The unfired hydrotalcite is, for example, a metal hydroxide having a layered crystal structure as represented by natural hydrotalcite (Mg ₆ Al ₂ (OH) ₁₆ CO _{3.4H 2} O), for example. It consists of a basic skeleton layer [Mg _1-X Al _X (OH) ₂ ] ^{X +} and an intermediate layer [(CO ₃ ) _{X / 2} · mH ₂ O] ^X- . The uncalcined hydrotalcite in the present invention is a concept including hydrotalcite-like compounds such as synthetic hydrotalcite. Examples of the hydrotalcite-like compound include those represented by the following formulas (I) and the following formula (II).

[M ²⁺ _1-x M ³⁺ x (OH) ₂ ] ^{x +} · [( ^Ann- ) _{x / n} · mH ₂ O] ^x- (I)
(In the formula, M ²⁺ represents a divalent metal ion such as Mg ₂₊ and Zn ²⁺ , M ³⁺ represents a ^trivalent metal ion such as Al ³⁺ and Fe ³⁺ , and An − represents CO ₃ ² and Cl. -Represents an n ^- valent anion such as-, NO _3- ^, 0 <x <1, 0 ≦ m <1, and n is a positive number.)
In the formula (I), M ²⁺ is preferably Mg ²⁺ , M ³⁺ is preferably Al ³⁺ , and ^An − is preferably CO ₃ ^2- .

M ²⁺ _x Al ₂ (OH) _{2x + 6-nz} ( ^An- ) _z · mH ₂ O (II)
(In the formula, M ²⁺ represents divalent metal ions such as Mg ²⁺ and Zn ²⁺ , An − represents ⁿ -valent anions such as CO ₃ ^2- , Cl ⁻ , NO ^3- , and x is 2 or more. Is a positive number, z is a positive number less than or equal to 2, m is a positive number, and n is a positive number.)
In the formula (II), M ²⁺ is preferably ^{Mg 2+} , and An − is preferably CO ₃ ^2- .

Semi-calcined hydrotalcite refers to a metal hydroxide having a layered crystal structure in which the amount of interlayer water is reduced or eliminated, which is obtained by calcining uncalcined hydrotalcite. The term "interlayer water" refers to "H ₂ O" described in the composition formulas of the above-mentioned uncalcined natural hydrotalcite and hydrotalcite-like compounds, which will be described using the composition formula.

On the other hand, the calcined hydrotalcite refers to a metal oxide having an amorphous structure obtained by calcining an uncalcined hydrotalcite or a semi-calcined hydrotalsite, in which not only the interlayer water but also the hydroxyl group disappears by condensation dehydration.

Unfired hydrotalcite, semi-fired hydrotalcite and calcined hydrotalcite can be distinguished by the saturated water absorption rate. The saturated water absorption rate of the semi-baked hydrotalcite is 1% by mass or more and less than 20% by mass. On the other hand, the saturated water absorption rate of unfired hydrotalcite is less than 1% by mass, and the saturated water absorption rate of calcined hydrotalcite is 20% by mass or more.

The "saturated water absorption rate" as used herein means that 1.5 g of unfired hydrotalcite, semi-fired hydrotalcite or fired hydrotalcite is weighed with a balance, the initial mass is measured, and then the temperature is 60 ° C. under atmospheric pressure. , The mass increase rate with respect to the initial mass when left to stand for 200 hours in a small environmental tester (SH-222 manufactured by Espec Co., Ltd.) set to 90% RH (relative humidity).
Saturated water absorption rate (% by mass)
= 100 × (mass after moisture absorption-initial mass) / initial mass (i)
Can be obtained at.

The saturated water absorption of the semi-baked hydrotalcite is preferably 3% by mass or more and less than 20% by mass, and more preferably 5% by mass or more and less than 20% by mass.

Further, uncalcined hydrotalcite, semi-calcined hydrotalcite and calcined hydrotalcite can be distinguished by the thermogravimetric reduction rate measured by thermogravimetric analysis. The thermogravimetric reduction rate of the semi-baked hydrotalcite at 280 ° C. is less than 15% by mass, and the thermogravimetric reduction rate at 380 ° C. is 12% by mass or more. On the other hand, the thermogravimetric reduction rate of uncalcined hydrotalcite at 280 ° C. is 15% by mass or more, and the thermogravimetric reduction rate of calcined hydrotalcite at 380 ° C. is less than 12% by mass.

For thermogravimetric analysis, 5 mg of hydrotalcite was weighed on an aluminum sample pan using TG / DTA EXSTAR6300 manufactured by Hitachi High-Tech Science Co., Ltd., and the nitrogen flow rate was 200 mL / min in an open state without a lid. It can be carried out from 30 ° C. to 550 ° C. under the condition of a heating rate of 10 ° C./min. The thermogravimetric reduction rate is calculated by the following formula (ii):
Thermogravimetric reduction rate (mass%)
= 100 × (mass before heating-mass when a predetermined temperature is reached) / mass before heating (ii)
Can be obtained at.

Further, uncalcined hydrotalcite, semi-calcined hydrotalcite and calcined hydrotalcite can be distinguished by the peak and relative intensity ratio measured by powder X-ray diffraction. Semi-baked hydrotalcite shows a peak in which 2θ is split into two in the vicinity of 8 to 18 ° by powder X-ray diffraction, or a peak with a shoulder due to the synthesis of the two peaks, and the peak or shoulder that appears on the low angle side. The relative intensity ratio (low-angle side diffraction intensity / high-angle side diffraction intensity) of the diffraction intensity (= low-angle side diffraction intensity) and the diffraction intensity of the peak or shoulder appearing on the high-angle side (= high-angle side diffraction intensity) is 0.001. ~ 1,000. On the other hand, uncalcined hydrotalcite has only one peak near 8 to 18 °, or the relative intensity ratio of the diffraction intensity of the peak or shoulder appearing on the low angle side and the peak or shoulder appearing on the high angle side is in the above range. Be outside. The calcined hydrotalcite does not have a characteristic peak in the region of 8 ° to 18 °, but has a characteristic peak in 43 °. Powder X-ray diffraction measurement is performed by a powder X-ray diffractometer (PANalytical, Empyrean) with anti-cathode CuKα (1.5405 Å), voltage: 45 V, current: 40 mA, sampling width: 0.0260 °, scanning speed: 0. The measurement was performed under the conditions of .0657 ° / s and the measured diffraction angle range (2θ): 5.0131 to 79.9711 °. The peak search uses the peak search function of the software attached to the diffractive device, "minimum significance: 0.50, minimum peak tip: 0.01 °, maximum peak tip: 1.00 °, peak base width: 2". It can be performed under the condition of "0.00 °, method: minimum value of second derivative".

The BET specific surface area of the semi-baked hydrotalcite is preferably 1 to 250 m ² / g, more preferably 5 to 200 m ² / g. The BET specific surface area of the semi-baked hydrotalsite is calculated by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device (Macsorb HM Model 1210 Mountech) according to the BET method and using the BET multipoint method. Can be done.

The average particle size of the semi-baked hydrotalcite is preferably 1 to 1,000 nm, more preferably 10 to 800 nm. The average particle size of the semi-baked hydrotalcite is the median diameter of the particle size distribution when the particle size distribution is prepared on a volume basis by laser diffraction scattering type particle size distribution measurement (JIS Z 8825).

As the component (B), one that has been surface-treated with a surface treatment agent can be used. As the surface treatment agent used for the surface treatment, for example, higher fatty acids, alkylsilanes, silane coupling agents and the like can be used, and among them, higher fatty acids and alkylsilanes are preferable. As the surface treatment agent, one kind or two or more kinds can be used.

Examples of the higher fatty acid include higher fatty acids having 18 or more carbon atoms such as stearic acid, montanic acid, myristic acid, and palmitic acid, and among them, stearic acid is preferable. These may be used alone or in combination of two or more. Examples of the alkylsilanes include methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, octadecyltrimethoxysilane, dimethyldimethoxysilane, octyltriethoxysilane, and n-octadecyldimethyl (n-octadecyldimethyl). Examples thereof include 3- (trimethoxysilyl) propyl) ammonium chloride. These may be used alone or in combination of two or more. Examples of the silane coupling agent include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyl (dimethoxy) methylsilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxy. Epoxy-based silane coupling agents such as silane; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and 11-mercaptoundecyltrimethoxysilane. 3-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldimethoxymethylsilane, N-phenyl-3-aminopropyltrimethoxysilane, N-methylaminopropyltrimethoxysilane, N- (2) Amino-based silane coupling agents such as -aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropyldimethoxymethylsilane; ureido-based silanes such as 3-ureidopropyltriethoxysilane Coupling agents, vinyl-based silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane and vinylmethyldiethoxysilane; styryl-based silane coupling agents such as p-styryltrimethoxysilane; 3-acrylicoxypropyltrimethoxy. An acrylate-based silane coupling agent such as silane and 3-methacryloxypropyltrimethoxysilane; an isocyanate-based silane coupling agent such as 3-isoxypropyltrimethoxysilane, bis (triethoxysilylpropyl) disulfide, and bis (triethoxysilylpropyl). ) A sulfide-based silane coupling agent such as tetrasulfide; phenyltrimethoxysilane, methacryloxypropyltrimethoxysilane, imidazole silane, triazinesilane and the like can be mentioned. These may be used alone or in combination of two or more.

The surface treatment of the component (B) can be performed, for example, by stirring and dispersing the untreated component (B) at room temperature with a mixer, adding and spraying a surface treatment agent, and stirring for 5 to 60 minutes. .. As the mixer, a known mixer can be used, and examples thereof include blenders such as V blenders, ribbon blenders and bubble cone blenders, mixers such as Henshell mixers and concrete mixers, ball mills and cutter mills. Further, when pulverizing the hygroscopic material with a ball mill or the like, a method of mixing the above-mentioned higher fatty acid, alkylsilanes or silane coupling agent and surface-treating the material is also possible. The treatment amount of the surface treatment agent varies depending on the type of the component (B), the type of the surface treatment agent, and the like, but is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the component (B).

The content of the component (B) in the composition of the present invention is not particularly limited, but the adhesion and sealing between the composition layer (sealing layer) containing the resin having a urethane bond formed by the composition and the plastic substrate. From the viewpoint of the transparency of the waterproof layer, the content is preferably 60% by mass or less, preferably 55% by mass or less, more preferably 50% by mass or less, and more preferably 45% by mass, based on 100% by mass of the total non-volatile content in the composition. More preferably, it is by mass or less. Further, from the viewpoint of sufficiently obtaining a hygroscopic effect, the content is preferably 10% by mass or more, more preferably 20% by mass or more, and more preferably 30% by mass or more per 100% by mass of the total non-volatile content in the composition. Is even more preferable.

Specific examples of the component (B) in the present invention include the following.
-DHT-4C (manufactured by Kyowa Chemical Industry Co., Ltd.): Semi-fired hydrotalcite (average particle size: 400 nm, BET specific surface area: 15 m ² / g)
-DHT-4A-2 (manufactured by Kyowa Chemical Industry Co., Ltd.): Semi-firing hydrotalcite (average particle size: 400 nm, BET specific surface area: 13 m ² / g)
-KW-2200 (manufactured by Kyowa Chemical Industry Co., Ltd.): Calcined hydrotalcite (average particle size: 400 nm, BET specific surface area: 146 m ² / g)
-DHT-4A (manufactured by Kyowa Chemical Industry Co., Ltd.): Unfired hydrotalcite (average particle size: 400 nm, BET specific surface area: 10 m ² / g)

<(C) Adhesive-imparting resin>
In order to make the sealing layer have higher adhesion to the plastic substrate, the composition of the present invention is blended with a tackifier resin (hereinafter, also abbreviated as "component (C)"). Can be done. The adhesive-imparting resin is not particularly limited, and is a turpen-based adhesive-imparting resin, terpene-phenol-based adhesive-imparting resin, rosin-based adhesive-imparting resin, hydrogenated terpene-based resin, aromatic-modified terpene-based resin, etc. Resins (aliphatic petroleum resin, hydrogenated alicyclic petroleum resin, aromatic petroleum resin, aliphatic aromatic copolymerized petroleum resin, alicyclic petroleum resin, dicyclopentadiene petroleum resin and hydride thereof, etc. ), Etc., but a rosin-based adhesive resin is preferable from the viewpoint of adhesiveness and compatibility. Examples of the rosin-based tackifier resin include modified rosins (ununiformized rosin, polymerized rosin, and other chemicals) obtained by unequalizing unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, and modifying them by polymerization. Specified rosin, etc.), various rosin derivatives, and the like. Examples of the rosin derivative include rosin esters in which unmodified rosin is esterified with alcohols, rosin esters such as modified rosin esters in which modified rosins such as hydrogenated rosin, disproportionated rosin, and polymerized rosin are esterified with alcohols. Unsaturated fatty acid-modified rosins obtained by modifying unmodified rosins and modified rosins (hydrogenated rosins, disproportionated rosins, polymerized rosins, etc.) with unsaturated fatty acids; unsaturated fatty acid-modified rosins obtained by modifying rosin esters with unsaturated fatty acids. Esters; Login alcohols obtained by reducing carboxy groups in unmodified rosins, modified rosins (hydrogenated rosins, disproportionated rosins, polymerized rosins, etc.), unsaturated fatty acid modified rosins or unsaturated fatty acid modified rosin esters; Examples thereof include metal salts of rosins (particularly rosin esters) such as modified rosins, modified rosins, and various rosin derivatives. Further, as the rosin derivative, a rosin phenol resin obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermally polymerizing them can also be used. The alcohols used to obtain the above rosin esters are dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and neopentyl glycol, trihydric alcohols such as glycerin, trimethylolethane and trimethylolpropane, and penta. Examples thereof include tetrahydric alcohols such as erythritol and diglycerin, and hexahydric alcohols such as dipentaerythritol.

The content of the component (C) in the composition is not particularly limited. However, from the viewpoint of adhesion between the composition layer (sealing layer) containing the resin having a urethane bond formed by the composition and the plastic substrate and the transparency of the sealing layer, the content thereof is set in the composition. Per 100% by mass of the total non-volatile content, 50% by mass or less is preferable, 40% by mass or less is preferable, 35% by mass or less is more preferable, 30% by mass or less is further preferable, and 20% by mass or less is most preferable. Further, from the viewpoint of sufficiently obtaining the effect of improving the adhesive strength, the content is preferably 3% by mass or more, more preferably 6% by mass or more, and 8% by mass, based on 100% by mass of the total non-volatile content in the composition. The above is more preferable.

<(D) catalyst>
In the composition of the present invention, from the viewpoint of the efficiency of the heavy addition reaction (urethanization reaction) in the component (A21) and the component (A22) (or the component (A21), the component (A22) and the component (A23)), A urethanization catalyst (hereinafter, also abbreviated as “component (D)”) can be blended. Examples of the urethanization catalyst include copper naphthenate, cobalt naphthenate, zinc naphthenate, dibutyltin dilaurate, and triethylamine. 1,4-diazabicyclo [2.2.2] octane, 2,6,7-trimethyl-1,4-diazabicyclo [2.2.2] octane and the like can be mentioned. The urethanization catalyst is (A21). It is preferable to use 0.01 to 1 part by mass with respect to 100 parts by mass of the total amount of the component and the (A22) component, or the total amount of the (A21) component, the (A22) component and the (A23) component.

<(E) Organic solvent>
From the viewpoint of the coatability of the composition, the efficiency of the urethanization reaction, and the like, it is preferable to add an organic solvent to the composition of the present invention. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone (hereinafter, also abbreviated as “MEK”), cyclohexanone, and acetic acid esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate. , Carbitols such as cellosolve and butylcarbitol, aromatic hydrocarbons such as toluene and xylene, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and the like. Only one kind of such organic solvent may be used, or two or more kinds thereof may be used in combination. The amount of the organic solvent is not particularly limited, but it is preferable to use an amount having a viscosity (25 ° C.) of the composition of 300 to 2000 mPa · s from the viewpoint of coatability.

<Other additives>
The composition of the present invention may further contain other additives different from the above-mentioned components. Examples of such additives include silica, alumina, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, boron nitride, aluminum borate, barium titanate, and titanium. Inorganic fillers such as strontium acid, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate; organic fillers such as rubber particles, silicon powder, nylon powder, fluorine powder; orben, Examples thereof include thickeners such as Benton; silicone-based, fluorine-based, and polymer-based defoaming agents or leveling agents; adhesion-imparting agents such as triazole compounds, thiazole compounds, triazine compounds, and porphyrin compounds. The inorganic filler or the hygroscopic metal oxide can be surface-treated with a surface treatment agent to improve its moisture resistance. Examples of the surface treatment agent include aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, vinylsilane-based coupling agents, imidazole silane-based coupling agents, organosilazane compounds, titanate-based coupling agents, and the like. Can be mentioned. These may be used alone or in combination of two or more.

<Manufacturing method of composition>
The composition of the present invention can be produced by mixing the above-mentioned components using a kneading roller, a rotary mixer, or the like.

<Use>
The composition of the present invention is for encapsulating a flexible electronic device in which electronic elements such as a thin film, an LCD element, an LED element, an EL element, and a solar cell are formed on a thin plastic substrate (plastic film). Since the sealing layer can be formed on the plastic substrate by a low temperature process, it can be particularly preferably used for sealing a flexible organic EL device. The thin plastic substrate (plastic film) of the flexible organic EL device may be, for example, poly (ethylene terephthalate) (PET), poly (butylene terephthalate) (PBT), poly (ethylene naphthalate) (PEN), polycarbonate (PC). , Polycarbonate (PI), Polysulfone (PSO) and Poly (p-phenylene ether sulfone) (PES) are used, and the composition of the present invention is used for these various plastic films. It is possible to form a sealing layer that is less likely to generate bubbles at the interface with and has excellent transparency. In particular, it acts particularly favorably on polyimide (PI) films. That is, it is possible to form a sealing layer having a particularly excellent effect of suppressing the generation of bubbles at the interface with the polyimide (PI) film.

In the composition of the present invention, the composition is directly applied to a necessary part of the plastic substrate so as to cover the electronic element formed on the plastic substrate of the flexible electronic device, and the coating film is dried by heating or hot air blowing. Then, by curing the dried coating film (layer of the composition), a sealing layer made of a cured product of the composition containing a resin having a urethane bond can be formed. Further, the composition of the present invention is applied onto the support, and the coating film is dried by heating or blowing with hot air to form a sealed coating film (layer of the composition) on the support. A sheet for preparation is prepared, the encapsulation sheet is laminated on a necessary part on a plastic substrate of a flexible electronic device, the layer of the composition is transferred, and the layer of the composition disposed on the plastic substrate is cured. Alternatively, by laminating the sealing sheet on the required part on the plastic substrate of the flexible electronic device and curing the layer of the composition as it is, from the cured product of the composition containing the resin having a urethane bond. Can form a sealing layer.

"Curing" is to promote the urethanization reaction in the dried coating film (layer of the composition). For example, the dried coating film (layer of the composition) exceeds room temperature and is not covered with room temperature. It is carried out by placing it in an environment having a temperature of 100 ° C. or lower (preferably 80 ° C. or lower, more preferably 40 ° C. or lower). The "room temperature" here means the "room temperature" specified in JIS Z 8703. Such curing may be carried out until the layer of the composition is completely cured (that is, no change in hardness of the layer of the composition is observed), or may be stopped before the layer of the composition is completely cured. The curing time can be shortened by curing at a temperature exceeding 80 ° C. By curing, the urethanization reaction (formation of a resin having a urethane bond, further urethanization (crosslinking) of the resin having a urethane bond, etc.) proceeds in the layer of the composition disposed on the plastic substrate, and the urethane bond is formed. A sealing layer made of a cured product of a composition containing a resin having a resin is obtained, and the sealing layer adheres to a plastic substrate and an electronic element with high adhesion to seal the electronic element.

From the viewpoint of realizing the object of the present invention at a higher level, in the present invention, the curing period applied to the coating film (layer of the composition) after drying varies depending on the environmental temperature for curing, but is generally 1. It is preferably about 10 days, more preferably about 3 to 10 days.

<Sealing sheet>
For example, the composition of the present invention made into a varnish by blending an organic solvent is applied onto the support, and the obtained coating film is dried by heating or blowing with hot air to dry the composition of the present invention on the support. A sealing sheet on which a layer of the composition is formed is obtained. The sealing sheet may be cured of the dried coating film (layer of the composition) formed on the support before being used for the sealing operation. This curing is for enhancing the adhesiveness of the layer of the composition formed on the support, and is preferably about 3 to 6 days.

Supports used for the sealing sheet include polyolefins such as polyethylene, polypropylene and polyvinyl chloride, polyethylene terephthalate (hereinafter abbreviated as "PET"), polyesters such as polyethylene naphthalate, polycarbonate and polyimide. Plastic film can be mentioned. PET is particularly preferable as the plastic film. Further, the support may be a metal foil such as an aluminum foil, a stainless steel foil, or a copper foil. The support may be subjected to a mold release treatment in addition to the mat treatment and the corona treatment. Examples of the mold release treatment include a mold release treatment using a mold release agent such as a silicone resin-based mold release agent, an alkyd resin-based mold release agent, and a fluororesin-based mold release agent. When the support has a release layer in the present invention, the release layer is also regarded as a part of the support. The thickness of the support is not particularly limited, but is preferably 20 to 200 μm, more preferably 20 to 125 μm from the viewpoint of handleability and the like.

In order to improve the moisture resistance of the sealing sheet, a plastic film having a barrier layer may be used as a support. Examples of the barrier layer include nitrides such as silicon nitride, oxides such as aluminum oxide, stainless steel foils, and metal foils of aluminum foils. Examples of the plastic film include the above-mentioned plastic film. As the plastic film having a barrier layer, a commercially available product may be used. Further, it may be a film obtained by composite laminating a metal foil and a plastic film. For example, examples of commercially available polyethylene terephthalate films with aluminum foil include "PET Tsuki AL1N30" manufactured by Tokai Toyo Aluminum Sales Co., Ltd. and "PET Tsuki AL3025" manufactured by Fukuda Metals Co., Ltd.

In the sealing sheet, the layer of the composition may be protected by a protective film. By protecting with a protective film, it is possible to prevent dust and the like from adhering to the surface of the resin composition layer and scratches. As the protective film, it is preferable to use a plastic film similar to the support. Further, the protective film may be subjected to a mold release treatment in addition to the matte treatment and the corona treatment. The thickness of the protective film is not particularly limited, but is usually 1 to 150 μm, preferably 10 to 100 μm.

If the support for the sealing sheet has moisture resistance and high transmittance, the sealing sheet is laminated to the required part of the object to be sealed and cured as it is. Therefore, it is possible to form a sealing structure having high moisture resistance. Examples of such a support having moisture resistance and high transmittance include a plastic film on which an inorganic substance such as silicon oxide (silica), silicon nitride, SiCN, or amorphous silicon is vapor-deposited on the surface. Examples of the plastic film include polyolefins such as polyethylene, polypropylene and polyvinyl chloride, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate and polyimide. PET is particularly preferable as the plastic film. Examples of commercially available moisture-proof plastic films include Tech Barrier HX, AX, LX, L series (manufactured by Mitsubishi Plastics) and X-BARRIER (manufactured by Mitsubishi Plastics) with further enhanced moisture-proof effect. Be done. As the support, a support having a multi-layer structure of two or more layers may be used.

In the sealing structure of the present invention, that is, the electronic element on the plastic substrate of the flexible electronic device is isolated from the air by a composition layer containing a resin having a urethane bond disposed in a fixed state on the plastic substrate. The thickness of the composition layer (sealing layer) containing the resin having a urethane bond is usually 3 μm to 200 μm, preferably 5 μm to 100 μm, and more preferably 5 μm to 50 μm.

<Flexible electronic device>
When a flexible electronic device in which an electronic element is sealed is manufactured by the sealing composition of the present invention, it is preferable to use the sealing sheet for sealing. That is, by laminating the sealing sheet of the present invention on the plastic substrate on which the electronic element of the flexible electronic device is formed, the flexible electronic device in which the electronic element is sealed can be obtained. If the sealing sheet is protected by a protective film, it is peeled off, and then the sealing sheet is laminated on the substrate and cured so that the resin composition layer is in direct contact with the substrate. The method of laminating the sealing sheet may be a batch method or a continuous method using a roll.

According to the sealing composition of the present invention, a sealing layer capable of maintaining high transparency and low haze and suppressing the generation of bubbles at the interface with the plastic substrate can be formed, so that the electronic device is an organic EL device. In a flexible electronic device that is a light emitting element such as the above, deterioration of the element can be prevented without lowering the light emitting efficiency of the device. Therefore, a flexible light emitting device with a long life can be realized. Further, since the sealing layer can be formed on the plastic substrate by the low temperature process, a flexible organic EL electronic device having a long life can be realized.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" in the components mean "parts by mass", respectively, unless otherwise specified.

The raw materials used in the examples and comparative examples are as follows.
(A21) Polyol
-Polyester SNT (manufactured by Nippon Synthetic Chemical Co., Ltd.): Polyester polyol (number average molecular weight 10,000, hydroxyl value 8 mgKOH / g, solid content 60% by mass)
Polyester S0091 (manufactured by Nippon Synthetic Chemical Co., Ltd.): Polyester polyol (number average molecular weight 21000, hydroxyl value 4.5 mgKOH / g, solid content 55% by mass)
-Kuraray Polyol P-2050 (manufactured by Kuraray): Polyester polyol (number average molecular weight 2000, hydroxyl value 56 mgKOH / g, viscosity 5200 mPa · s)
-Fine Tuck CT-6030 (manufactured by DIC): Acrylic polyol (viscosity 5000 mPa · s, solid content 45% by mass)
(A22) Polyfunctional isocyanate

Coronate L (manufactured by Tosoh Corporation): Trimethylolpropane-tolylene diisocyanate trimer adduct, NCO content 13.2% by mass
-Coronate HX (manufactured by Tosoh Corporation): isocyanurate form of hexamethylene diisocyanate, NCO content 21.1% by mass
Amine-based curing agent (2,4,6-tris (diaminomethyl) phenol, hereinafter abbreviated as "TAP")

(B) Hygroscopic filler DHT-4C (manufactured by Kyowa Chemical Industry Co., Ltd.): Semi-fired hydrotalcite (average particle size: 400 nm, BET specific surface area: 15 m ² / g)
N41S (manufactured by Toda Kogyo Co., Ltd.): Calcined hydrotalcite (average particle size: 40 nm, BET specific surface area: 133 m ² / g)

(C) Adhesive-imparting resin KE-359 (manufactured by Arakawa Chemical Co., Ltd.): Rosin ester (softening point 94-104 ° C., hydroxyl value 38-47 mgKOH / g)
-Alcon P125 (manufactured by Arakawa Chemical Co., Ltd.): Cyclohexane ring-containing hydrogenated petroleum resin (softening point 125 ° C)

(E) Organic solvent , toluene, swazole # 1000 (manufactured by Maruzen Petrochemical Co., Ltd.): Aromatic mixed solvent, methyl ethyl ketone (MEK)

Polyolefin resin T-YP757B (manufactured by Seikou PMC Co., Ltd.): Maleic anhydride-modified styrene-isobutylene-styrene copolymer, maleic anhydride group concentration 0.464 mmol / g, number average molecular weight 100,000
T-YP766 (manufactured by Seikou PMC Co., Ltd.): Glycyzyl methacrylate-modified styrene-isobutylene-styrene copolymer, glycidyl group concentration 0.638 mmol / g, number average molecular weight 100000

The compositions of Examples and Comparative Examples were prepared according to the following procedure. The compounding was carried out in the amount shown in Table 1. The amounts of the components other than the organic solvent shown in Table 1 are values converted into non-volatile components.

<Example 1>
18 parts of rosin ester (KE-359, 60% swazole # 1000 solution) and 20 parts of semi-baked hydrotalcite (DHT-4C) are dispersed in 8 parts of polyester polyol (Kuraray polyol P-2050) with 3 rolls. , A mixture was obtained. The obtained mixture was mixed with 5 parts of polyester polyol (Polyester SNT), 45 parts of polyester polyol (Polyester S0091), 3.3 parts of polyfunctional isocyanate (Coronate L) and 20 parts of MEK, and the obtained mixture was mixed at high speed. The varnish was prepared by uniformly dispersing it with a rotating mixer. The obtained varnish was uniformly applied on a mold release-treated surface of a PET film (thickness 38 μm) treated with a silicone-based mold release agent with a die coater, heated at 100 ° C. for 3 minutes, and then at 40 ° C. After heating for 3 days, a sealing sheet having a resin composition layer having a thickness of 20 μm was obtained. The viscosity (25 ° C.) of the varnish is 1200 mPa · s, and the equivalent ratio (NCO / OH) of the hydroxyl group (-OH) of all polyester polyols in the varnish to the isocyanate group (-NCO) of all polyfunctional isocyanates is 0. It was .8 / 1.

<Example 2>
A varnish and a sealing sheet were prepared in the same manner as in Example 1 except that two parts of Coronate HX were used as the polyfunctional isocyanate. The viscosity (25 ° C.) of the varnish is 1200 mPa · s, and the equivalent ratio (NCO / OH) of the hydroxyl group (-OH) of all polyester polyols in the varnish to the isocyanate group (-NCO) of all polyfunctional isocyanates is 1. It was 2/1.

<Example 3>
A varnish and a sealing sheet were prepared in the same manner as in Example 1 except that one part of Coronate HX was used as the polyfunctional isocyanate. The viscosity (25 ° C.) of the varnish is 1200 mPa · s, and the equivalent ratio (NCO / OH) of the hydroxyl group (-OH) of all polyester polyols in the varnish to the isocyanate group (-NCO) of all polyfunctional isocyanates is 0. It was .6 / 1.

<Example 4>
A varnish and a sealing sheet were prepared in the same manner as in Example 1 except that the amount of semi-baked hydrotalcite (DHT-4C) used was changed from 20 parts to 12 parts. The viscosity (25 ° C.) of the varnish is 900 mPa · s, and the equivalent ratio (NCO / OH) of the hydroxyl group (-OH) of all polyester polyols in the varnish to the isocyanate group (-NCO) of all polyfunctional isocyanates is 0. It was .8 / 1.

<Example 5>
A varnish and a sealing sheet were prepared in the same manner as in Example 1 except that the amount of semi-baked hydrotalcite (DHT-4C) used was changed from 20 parts to 6 parts. The viscosity (25 ° C.) of the varnish is 700 mPa · s, and the equivalent ratio (NCO / OH) of the hydroxyl group (-OH) of all polyester polyols in the varnish to the isocyanate group (-NCO) of all polyfunctional isocyanates is 0. It was .8 / 1.

<Comparative Example 1>
In 128 parts of cyclohexane ring-containing hydride petroleum resin (Arcon P125, 60% swazole # 1000 solution), 24 parts of maleic anhydride-modified styrene-isobutylene-styrene copolymer (T-YP757B), glycidylmethacrylate-modified styrene-isobutylene-styrene. 18 parts of the copolymer (T-YP766) and 0.5 part of the amine-based curing agent (TAP) were blended, and the obtained mixture was uniformly dispersed with a high-speed rotary mixer to prepare a varnish. The obtained varnish was uniformly applied on the release-treated surface of a PET film (thickness 38 μm) treated with a silicone-based mold release agent with a die coater, and heated at 130 ° C. for 60 minutes to increase the thickness. A sealing sheet having a composition layer of 20 μm was obtained.

<Comparative Example 2>
In 128 parts of cyclohexane ring-containing hydride petroleum resin (Arcon P125, 60% swazole # 1000 solution), 24 parts of maleic anhydride-modified styrene-isobutylene-styrene copolymer (T-YP757B), glycidylmethacrylate-modified styrene-isobutylene-styrene. 18 parts of the copolymer (T-YP766) and 40 parts of the calcined hydrotalcite (N41S) were dispersed in three rolls to obtain a mixture. 0.5 part of an amine-based curing agent (TAP) was added to the obtained mixture, and the obtained mixture was uniformly dispersed with a high-speed rotary mixer to prepare a varnish of a resin composition. The obtained varnish was uniformly applied on the release-treated surface of a PET film (thickness 38 μm) treated with a silicone-based mold release agent with a die coater, and heated at 130 ° C. for 60 minutes to increase the thickness. A sealing sheet having a composition layer of 20 μm was obtained.

The composition layers of the encapsulation sheets of Examples and Comparative Examples obtained as described above were evaluated as follows. The results are shown in Table 1.

1. 1. Evaluation of total light transmittance and haze The sealing sheet (thickness of composition layer: 20 μm) produced in Examples and Comparative Examples was cut into a length of 50 mm and a width of 20 mm, and the cut sealing sheet was cut into a glass plate. A batch type vacuum laminator (Nichigo Morton, V-160) was applied to (microslide glass with a length of 76 mm, a width of 26 mm, and a thickness of 1.2 mm, white slide glass S1112 edged by Matsunami Glass Industry Co., Ltd. No. 2). Laminated using. The laminating conditions were a temperature of 80 ° C., a reduced pressure time of 30 seconds, and then a pressure of 0.3 MPa for 30 seconds. Then, the PET film of the sealing sheet was peeled off, and the same glass plate as above was further laminated on the exposed composition layer to prepare a laminated body. The light transmittance spectrum of the obtained laminate was measured with D65 light using a haze meter HZ-V3 (halogen lamp) manufactured by Suga Test Instruments Co., Ltd. with air as a reference, and evaluated according to the following criteria.

[Total light transmittance]
Good (○): 90% or more Possible (△): 85% or more and less than 90% Defective (×): Less than 85%

[Haze]
Good (○): Less than 2% Possible (△): 2% or more and less than 5% Defective (×): 5% or more

2. 2. Evaluation of foam resistance The sealing sheet (thickness of composition layer: 20 μm) produced in Examples and Comparative Examples was cut into a length of 40 mm and a width of 40 mm, and a roll-type laminator (VA-420A, manufactured by Taisei Laminator) was manufactured. ) Was laminated on a polyimide film (length 50 mm, width 50 mm, thickness 50 μm, manufactured by Ube Kosan Co., Ltd., product number Upirex-S). The laminating conditions were a temperature of 25 ° C., a speed of 1 m / min, and a pressure of 0.3 MPa. Then, the PET film was peeled off, and a PET film (length 40 mm, width 40 mm, thickness 100 μm, manufactured by Toray Industries, Inc., Lumirror) was further laminated on the exposed composition layer under the same conditions as above. Further, the laminate of Example 1-5 was cured at 40 ° C. for 3 days. Then, the laminate was stored in a constant temperature and high humidity bath at 85 ° C. and 85% RH for 5 days, and then the degree of foaming was visually evaluated according to the following criteria. The results are shown in Table 1.
Good (○): No foaming Defective (×): With foaming

The flexible electronic device encapsulation composition of the present invention can form a encapsulating layer that can maintain high transparency, low haze, and suppress the generation of air bubbles at the interface with the plastic substrate. Therefore, in particular, in a flexible electronic device in which the electronic element is a light emitting element such as an organic EL element, it is possible to prevent the device from deteriorating without lowering the luminous efficiency of the device, which contributes to extending the life of the flexible light emitting element device.

Claims (7)

A composition for encapsulating a flexible electronic device, comprising (A1) a resin having a urethane bond and / or (A2) a compound for producing a resin having a urethane bond.
(A1) The resin having a urethane bond is a polyurethane resin in which the polyester polyurethane skeleton is 60 to 100% by mass of the whole.
(A2) The resin-forming compound having a urethane bond contains (A21) a polyol and (A22) a polyfunctional isocyanate.
(A21) A composition used for forming a sealing layer in which 60 to 100% by mass of the polyol is composed of a polyester polyol and has an interface with a polyimide substrate of a flexible electronic device. The composition according to claim 1, further comprising (B) a hygroscopic filler. The composition according to claim 1 or 2, wherein the flexible electronic device is a flexible organic EL device. A sealing layer comprising a support and a layer of the composition according to claim 1 or 2 formed on the support, wherein the layer of the composition has an interface with a polyimide substrate of a flexible electronic device. Flexible electronic device encapsulation sheet used to form. The sheet according to claim 4, wherein the flexible electronic device is a flexible organic EL device. The electronic device formed on the polyimide substrate is sealed by a sealing layer containing a resin having a urethane bond formed by the composition according to claim 1 or 2, and the polyimide substrate and the sealing layer are sealed. A flexible electronic device that has an interface with. The flexible electronic device according to claim 6, wherein the electronic element formed on the polyimide substrate is an organic EL element, and the flexible electronic device is a flexible organic EL device.