Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified... – With bonding or intermediate layer of specified composition
Reexamination Certificate
2000-11-30
2003-04-29
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
With bonding or intermediate layer of specified composition
C428S413000, C428S414000, C428S415000, C428S417000, C525S523000, C525S529000, C523S400000, C523S440000, C349S122000, C349S153000, C156S099000, C156S330000
Reexamination Certificate
active
06555187
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a sealant composition for a liquid crystal display cell, a production process for a liquid crystal display cell and a liquid crystal display element.
BACKGROUND ART
In recent years, a liquid crystal display panel (hereinafter referred to as a liquid crystal display element), having characteristics of a light weight and a thin size has come to be widely used as display panels for various devices including a personal computer. As liquid crystal display elements have come to be increasingly used, a use environment thereof has become more and more severe, and large-sized, homogeneous and high quality liquid crystal display cells have been desired.
A liquid crystal sealant composition means a thermosetting resin composition used for forming a cell prepared by charging liquid crystal between transparent glass substrates or transparent plastic substrates suitably provided with transparent electrodes and an alignment film which are important as members for constituting a liquid crystal display element and sealing it off so that it does not leak outsides.
Proposed are, for example, single liquid type thermosetting liquid crystal sealant compositions comprising an epoxy resin and a hydrazide base potential curing agent for epoxy resin and suitably containing a solvent. The above composition group satisfies sufficiently fundamental performances for sealing characteristics of a liquid crystal cell, that is, an adhesive sealing property, a heat resistance, an electric insulating property and a property of not staining liquid crystal, but bubbles through a seal (seal leak) have been liable to be generated in a single layer press hot bonding system which has been regarded as important as one of production systems for homogeneous and high quality liquid crystal display cells.
On the other hand, particularly a large-sized liquid crystal display has strongly been required in recent rears, and as a substrate used for a liquid crystal cell transfers to a large size, a liquid crystal sealant composition having high adhesion reliability which can meet such a large-sized substrate is required to be developed. At the same time, desired as well to be developed is a liquid crystal sealant composition which can meet a production system of a liquid crystal cell by a single layer press hot bonding system.
Further, the existing situation is that a liquid crystal sealant composition with which a high quality liquid crystal element capable of being used under further severer environment than ever, for.example, under a high humidity environment at 80° C. can be produced has more and more strongly been required in recent years.
In order to produce a more homogeneous and higher quality liquid crystal display panel, a hot bonding step is actively tried to be improved in a production site of the above field. It has so far been recognized that, for example, a system in which many substrates are subjected to hot press bonding in a lump sum is good from a viewpoint of a productivity, and the system has widely been put to practical use. However, the system of the hot press bonding is a production system in which many sets of two substrates for constituting a liquid crystal cell having one substrate coated with a liquid crystal sealant composition are subject to cramping in vacuum in a piled-up state and then go through a hot bonding step in a heating furnace, and it has had the problem that the cells tend to make more or less a difference in a quality depending on upper, middle and lower positions in the pile.
Accordingly, the existing situation is that a single layer press hot bonding system, that is, a method in which a set of two transparent substrates for a liquid crystal cell is subjected set by set to hot press bonding for sealing has come to be proposed.
In the above single layer press hot bonding system, however, a publicly known liquid crystal sealant composition of a single liquid hot curing type has been liable to bring about problems such as generation of bubbles through a seal (seal leak), a marked disturbance in a seal width and an increase in stain in the vicinity of a sealed part (generation of inferior liquid crystal display).
Accordingly, the existing situation is that strongly required is a novel liquid crystal sealant composition which can meet the single layer press hot bonding system and exhibit high productivity and which is durable under a high humidity environment of 80° C.
Under such social background as described above, a subject to be solved is to provide a liquid-crystal sealant composition which can meet a substrate for a large-sized liquid crystal element and exhibit high productivity in the single layer press hot bonding system and which can provide a liquid crystal element durable over a long period of time even under a high humidity environment of 80° C., more specifically to provide a liquid crystal sealant composition which is highly fitted to single layer press and in which a liquid crystal display cell obtained using the composition is excellent in a heat resistance and a moisture barrier property and can secure dimensional stability and long-time display stability.
Further, another subject is to provide a production process for a liquid crystal cell using the above liquid crystal sealant composition.
DISCLOSURE OF THE INVENTION
Intensive investigations repeated by the present inventors in order to solve the subjects described above have resulted in finding that the subjects described above can be achieved by a composition comprising a specific epoxy resin, a specific potential curing agent for epoxy resin, a specific rubber-like polymer fine particle, a specific inorganic filler, a specific high softening point-polymer fine particle, and if necessary, a silane coupling agent, a curing accelerator, a solvent and a gap-forming controller each falling in a specific range, and thus the present invention has been completed.
That is, the liquid crystal sealant composition of the present invention comprises the following items [1] to [11]:
[1] A liquid crystal sealant-composition comprising an epoxy resin composition, wherein
(a) an aqueous solution obtained by admixing the above composition with the same mass of purified water has an ionic conductivity of 1 mS/m or less and
(b) a coated material obtained by coating the above epoxy resin composition in a thickness of 50 &mgr;m and subjecting it to heat treatment at 80 to 100° C. for 20 minutes has a viscosity of 50 to 10000 Pa·s at 80 to 100° C. by an E type viscometer; and in a cured matter of the above epoxy resin composition,
(c) the cured matter of the above composition has a linear expansion coefficient of 10×10
−5
mm/mm/° C. or less at 0° C. to 100° C., which is determined by means of a thermomechanical analyzer (TMA),
(d) the cured matter of the above composition has a glass transition temperature Tg of 100° C. or higher, which is deteried by means of a thermomechanical analyzer (TMA), and
(e) a cured matter having a thickness of 100 &mgr;m which is formed from the above composition has a moisture permeability of 200 g/m
2
·24 hours or less at 80° C. at which moisture passes through the above cured matter.
[2] The liquid crystal sealant composition as described in the above item [1], comprising:
20 to 88.9 mass % of an epoxy resin (1) having 1.2 or more epoxy groups on an.average in a molecule,
1 to 15 mass % of a rubber-like polymer fine particle (2) having a softening point of 0° C. or lower and a primary particle diameter of 5 &mgr;m or less,
5 to 50 mass % of an inorganic filler (3),
5 to 30 mass.% of a thermally active potential curing agent for epoxy resin (4), and
0.1 to 9.5 mass % of a high softening point-polymer fine particle (5) having a softening point of 50° C. or higher and a primary particle diameter of 2 &mgr;m or less.
[3] The liquid crystal sealant composition as described in the above item [2], further comprising 0.1 to 5 mass % of a silane coupling agent (6) and 0.1 to 10 mass %
Dawson Robert
Feely Michael J
Mitsui Chemicals Inc.
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