Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1998-08-28
2001-07-31
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C313S504000, C313S506000, C313S512000, C257S099000, C257S100000, C428S913000, C428S917000
Reexamination Certificate
active
06268071
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an organic EL (electroluminescent) device using an organic compound, and more specifically to an improvement in or relating to an adhesive agent for fixing a sealing plate in place to protect an organic EL structure stacked on a substrate.
In recent years, organic EL devices have been under intensive investigation. One such device is basically built up of a thin film form of hole transporting material such as triphenyldiamine (TPD) deposited by evaporation on a hole injecting electrode, a light emitting layer of fluorescent material such as an aluminum quinolinol complex (Alq
3
) laminated thereon, and a metal (electron injecting) electrode of a metal having a low work function such as Mg and formed on the light emitting layer. This organic EL device now attracts attentions because a very high luminance ranging from several hundreds to tens of thousands cd/m
2
can be achieved with a voltage of approximately 10 V.
A grave problem with an organic EL device is that it is acutely sensitive to moisture. Exposure of the organic EL device to moisture, for instance, causes a light emitting layer to peel off electrode layers, or materials forming part thereof to degenerate. This results in another problem that non-light emission spots called dark spots occur or any consistent light emission cannot be kept.
One approach known to solve this problem is to fix an airtight case, a sealing layer or the like closely on a substrate to cover an organic EL multilayer structure, thereby shielding it from the outside, as typically disclosed in JP-A's 5-36475, 5-89959 and 7-169567.
Even with the provision of such a sealing layer, however, several problems still arise; as driving time goes by, the light emission luminance decreases or the dark spots occur. If the dark spots become large, then the device will deteriorate and, in the worst case, the device will be unable to work.
OBJECT, AND SUMMARY OF THE INVENTION
The present invention has for its object to provide an organic EL device which, in terms of deterioration with time, is reduced as much as possible so as to have an ever longer service life, so that its initial performance can be maintained over a long period of time.
As a consequence of intensive studies of factors ascribable to a deterioration in an organic EL device, the inventors have found that one leading cause of such a deterioration is the reactions of gases released out of a sealing adhesive agent with structural films of the organic EL device, and so have accomplished the present invention.
The aforesaid object is achieved by the inventions defined below.
(1) An organic electroluminescent device comprising a substrate, an organic EL structure stacked on said substrate, a sealing plate located on said organic EL structure with a predetermined space therebetween, and a sealing adhesive agent for fixing said sealing plate on said substrate and closing up said organic EL structure, wherein:
said sealing adhesive agent is a photo-curing type adhesive agent which, after photo-curing, generates gases under heating conditions of 85° C. and 60 minutes, in which gases a total amount of a low-molecular straight-chain aliphatic hydrocarbon which may have a substituent, an aromatic hydrocarbon which may have a substituent, an alicyclic hydrocarbon which may have a substituent, and a heterocyclic compound which may have a substituent, and a siloxane is 200 &mgr;g/g or lower calculated as benzene.
(2) The organic EL device according to (1), wherein said gases generated contain:
propylene carbonate≦25 &mgr;g/g calculated as benzene, propylene glycol≦15 &mgr;g/g calculated as benzene, and toluene≦20 &mgr;g/g calculated as benzene.
(3) The organic EL device according to (1), wherein said gases contains iodobenzene in an amount of at least 1 &mgr;g/g calculated as benzene.
(4) The organic EL device according to (1), wherein said adhesive agent is a cation polymerization epoxy adhesive agent of an ultraviolet curing type.
(5) An organic EL device comprising a substrate, an organic EL structure stacked on said substrate, a sealing plate located on said organic EL structure with a given space therebetween, and a sealing adhesive agent for fixing said sealing plate on said substrate and closing up said organic EL structure, wherein:
said sealing adhesive agent is a photo-curing type adhesive agent which, after photo-curing, generates gases under heating conditions of 85° C. and 60 minutes, said gases containing:
propylene carbonate≦25 &mgr;g/g calculated as benzene,
propylene glycol≦15 &mgr;g/g calculated as benzene, and
toluene≦20 &mgr;g/g calculated as benzene.
(6) The organic EL device according to (5), wherein said gases contains iodobenzene in an amount of at least 1 &mgr;g/g calculated as benzene.
REFERENCES:
patent: 5909081 (1999-06-01), Eida et al.
patent: 0 859 539 (1998-08-01), None
patent: 3-261091 (1991-11-01), None
patent: 5-36475 (1993-02-01), None
patent: 5-89959 (1993-04-01), None
patent: 8-302340 (1996-11-01), None
patent: 96/25020 (1996-08-01), None
Technical Information Paper 30Y-296C and partial translation (Nov. 1997).
Technical Information Paper 30Y-296D and partial translation. (no date).
Ebisawa Akira
Endo Hiroyuki
Kato Hideo
Onitsuka Osamu
Shimamura Junichi
Garrett Dawn L.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
TDK Corporation
Yamnitzky Marie
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