Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-03-23
2003-07-01
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S100000, C522S071000, C522S077000, C522S083000, C524S107000, C524S114000, C156S272200, C156S275100, C156S275300, C156S326000, C156S325000, C156S327000, C156S330000, C156S331100, C428S001100, C428S001500, C428S345000, C428S3550RA, C428S3550EP, C427S508000, C427S516000, C427S207100
Reexamination Certificate
active
06586496
ABSTRACT:
FIELD OF THE TECHNIQUE
The present invention relates to a photo-curable resin composition for use as a sealing material, which comprises a compound having oxetane ring, as well as to a method for sealing an article, such as flat panel.
BACKGROUND OF THE TECHNIQUE
In recent years, flat panel displays using various display elements have been developed and brought into industrial production in the electronic and electric industries. Many of these displays are made of cells of glass or plastic flat panels enclosing the display elements with sealing. Representatives of such displays are liquid crystal (LC) displays and electroluminescence (EL) displays.
In general, LC display cell has the structure in which a layer of liquid crystal is placed between two substrate glass boards and is sealed along the circumference with a sealing material. Heretofore, thermosetting epoxy resins have been used for the sealing material. There was, however, a problem that a high productivity cannot be expected using such a sealing material of thermosetting epoxy resin, since it is necessary to heat the resin at a temperature as high as 150-180° C. for about two hours in order to attain sufficient curing of the epoxy resin.
On the other hand, EL displays are superior in the high brightness, high efficiency and high responding speed and have attracted notice as flat panel display of next generation. As the display element, inorganic and organic EL display elements have been proposed and inorganic EL display elements are now in practical use for, for example, back illumination of a wrist watch and so on. Organic EL display elements are superior in the high brightness, high efficiency, high responding speed and polychroism, as compared with inorganic EL display elements, but have lower heat resistance with a heat stability temperature of some 60-80° C. In sealing an organic EL display cell, there was, thus, a problem that satisfactory heat curing of the sealing is not attainable with thermosetting epoxy resin.
For obviating these problems, it has been examined to use a photo-curable sealing material capable of being cured promptly at lower temperatures.
As photo-curable sealing material, there are, in a rough grouping, two types, namely, a photo-radical polymerization type (photo-radical type) and a photo-cationic polymerization type (photo-cationic type).
A photo-radical type sealing material, for which an acrylic resin has predominantly been used, has an advantage of capability of employing a wide variety of monomers and oligomers of acrylates, nevertheless it exhibits an insufficient resistance to moisture permeation and is further requested to lower its rate of volumetric contraction and to improve its adhesive strength.
A photo-cationic type sealing material, for which an epoxy resin has predominantly been used, has a relatively better adhesive strength, nevertheless it is requested to be further improved in its photo-sensibility, prompt curability and moisture permeation resistance.
The object of the present invention is to provide a photo-curable resin composition for sealing material for, in particular, display cells, which is curable at lower temperatures and which is superior in the photosensibility, in the prompt curing property, in the adhesive property, in the ability of forming a cured product exhibiting a high adhesive strength and in the resistance to moisture permeation, permits better productivity of the sealed product, such as display panels etc., and can be used favorably, above all, for flat panels of displays based on liquid crystal and on electroluminescence, and to provide a sealing material as well as to provide a sealing method using such a sealing material.
DISCLOSURE OF THE INVENTION
The inventors discovered from sound researches that the problems inherent in the conventional photo-curable resin composition for sealing material mentioned above can be obviated by using, for a photo-curable resin composition as the starting mixture of the sealing resin, a compound having oxetane ring, a photoinitiator for cationic polymerization and a silane coupling agent and that a photo-curable resin composition for sealing material, which is superior in the photosensibility, prompt curability, adhesive strength, resistance to moisture permeation and heat resistance, can be obtained by controlling the viscosity of the composition suitably, whereby the present invention has been completed.
Thus, the present invention resides in the following photo-curable resin composition, sealing material and method for sealing such a sealing material:
(1) A photo-curable resin composition for sealing material, comprising
(A) a compound having oxetane ring,
(B) a photoinitiator for cationic polymerization and
(C) a silane coupling agent,
wherein the composition has a viscosity in the range from 0.01 to 300 Pa.s at 25° C.
(2) The photo-curable resin composition for sealing material as defined in the above (1), which comprises further
(D) an inorganic filler of microparticles.
(3) The photo-curable resin composition for sealing material as defined in the above (1) or (2), which comprises further
(E) a compound having epoxy group.
(4) The photo-curable resin composition for sealing material as defined in any one of the above (1) to (3), wherein it comprises
(A) the compound having oxetane ring, in a proportion of 0.1-99.8% by weight,
(B) the photoinitiator for cationic polymerization, in a proportion of 0.1-10% by weight
(C) the silane coupling agent, in a proportion of 0.1-30% by weight,
(D) the microparticulate inorganic filler, in a proportion of 0-70% by weight and
(E) the compound having epoxy group, in a proportion of 0-99.7% by weight.
(5) The photo-curable resin composition for sealing material as defined in any one of the above (1) to (4), wherein the cured resin obtained by curing the photo-curable resin composition exhibits, under the condition of a temperature of 80° C. and a relative humidity of 95%, a moisture permeability of 250 g/(m
2
·24 hr) or less and an adhesive strength onto glass plate of 4.9 MPa (50 kgf/cm
2
) or more.
(6) A sealing material comprising the photo-curable resin composition as defined in any one of the above (1) to (5).
(7) A sealing material for flat panel display comprising the photo-curable resin composition as defined in any one of the above (1) to (5).
(8) A sealing material for liquid crystal display or electroluminescence display, comprising the photo-curable resin composition as defined in any one of the above (1) to (5).
(9) A method for sealing an article to be sealed, comprising applying the sealing material as defined in the above (6) to the article and subjecting the material to curing.
(10) A method for sealing a display cell of liquid crystal display or electroluminescence display, comprising applying the sealing material as defined in the above (8) to the cell and subjecting the material to curing.
(11) Sealed articles comprising cured layer of the sealing material as defined in the above (6), which seals the article.
(12) A display based on liquid crystal or electroluminescence, comprising a display cell sealed by the sealing material as defined in the above (8).
Below, the present invention will be described in more detail.
<<The Compound (A) Having Oxetane Ring>>
For the compound (A) having oxetane ring to be incorporated in the composition according to the present invention, every compound having at least one oxetane ring represented by the formula (1)
may be employed. There may be recited, for example, compounds having 1 to 15, preferably 1 to 10, especially preferably 1 to 4 oxetane rings.
<Compounds Having One Oxetane Ring>
Every compound having one oxetane ring may be used for this, wherein preference is given, for example, to those represented by the formula (2)
in which Z, R
1
and R
2
have the meanings as given below:
Z stands for oxygen atom or sulfur atom.
R
1
denotes hydrogen atom; fluorine atom; an alkyl group having 1-6 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl or hexyl; a fluoroalkyl group having 1-6 carb
Kikuta Yoshio
Mizuta Yasushi
Nagata Kei
Ota Masahiro
Takamatsu Yasushi
Burns Doane , Swecker, Mathis LLP
McClendon Sanza L.
Mitsui Chemicals Inc.
Seidleck James J.
LandOfFree
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