JPH0480718A - Manufacturing method of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To improve long-term reliability by previously forming an adhesive layer on the peripheral edge of at least one substrate, then superposing two sheets of the substrates and sealing the substrates. CONSTITUTION:The adhesive layer is previously formed in the peripheral edge of at least one substrate and thereafter, two sheets of the substrates are superposed and are sealed in the case of production of the liquid crystal display panel which consists of two sheets of the substrates disposed with transparent electrodes and a medium layer formed by dispersing a liquid crystal into a medium and is crimped with the medium layer by means of two sheets of the substrates in such a manner that the transparent electrode surfaces face each other. While the adhesive is not particularly limited, a hot melt adhesive, UV curing type adhesive, epoxy resin adhesive, thermosetting type adhesive, etc., are adequately used. After the adhesive is previously applied in the peripheral edge of at least one substrate and thereafter, the other substrate is superposed thereon and the substrates are hermetically sealed in such a manner and, therefore, the hydroscopicity is small and the long-term reliability is excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a polymer-dispersed liquid crystal display panel with excellent water resistance.

The liquid crystal display panel of the present invention can be used for various displays, optical shutters, control devices, etc., and can be particularly suitably used as a liquid crystal display panel for large screens.

[Prior art and its problems]

Recently, a polymer-dispersed liquid crystal display panel comprising a medium layer in which liquid crystals are dispersed has been proposed in Japanese Patent Publication No. 58-501631.

The conventional method for sealing this polymer-dispersed liquid crystal display panel is to seal the peripheral edges of two substrates with a sealant in advance, fill the liquid crystal through the injection hole, and then
It is not possible to use a method of sealing the injection port.

Therefore, in order to seal this polymer-dispersed liquid crystal display panel, a method has been adopted in which the polymer-dispersed liquid crystal is sandwiched between two substrates, and then the periphery of the substrates is sealed using an epoxy resin.

In this case, there was a problem in that the epoxy resin could not be sufficiently cured in order to prevent the liquid crystal inside the cell from deteriorating due to heat. As a result, the sealing becomes insufficient, moisture easily enters the inside, and the performance of the liquid crystal display panel deteriorates during long-term use.

[Means for solving problems]

The present inventors conducted extensive research in order to solve the above problems, and as a result, they arrived at the present invention.

The present invention consists of two substrates on which transparent electrodes are disposed, and a medium layer in which liquid crystal is dispersed in the medium, and the medium layer is
In manufacturing a liquid crystal display panel in which the transparent electrode surfaces are sandwiched between two substrates, an adhesive layer is formed in advance on the peripheral edge of at least one of the substrates, and then an adhesive layer is formed on the peripheral edge of at least one substrate.
The present invention relates to a method of manufacturing a liquid crystal display panel, which is characterized by stacking and sealing two substrates.

The adhesive used in the present invention is not particularly limited, but hot melt adhesives, ultraviolet curable adhesives, epoxy resin adhesives, thermosetting adhesives, and the like can be suitably used.

The medium layer of the present invention is a medium layer in which liquid crystal is dispersed in the medium, and a specific example thereof is a polymer-dispersed liquid crystal, such as N CA P (N CA P ( Nematic Curvilin
ear Aligned Phase: Nematic curve aligned phase) liquid crystal (Special Publication No. 58-501631)
, latex-incorporated liquid crystal (Japanese Patent Application Laid-Open No. 60-252687
), a material in which liquid crystal microdroplets are dispersed in epoxy resin (Japanese Patent Publication No. 61-502128), or a liquid crystal composite film with a network structure prepared by a solvent casting method (Po
lyIler Preprints, Japan vo
l, 37. No. 8.2450 (1988)).

〔Example〕

EXAMPLES The present invention will be explained in further detail by way of Examples below.

Example 1 10% PVA aqueous solution, liquid crystal, dichroic dye (PVA:liquid crystal = 1:3.5 (weight ratio), dichroic dye is 3% by weight of liquid crystal)
] was thoroughly mixed, and this was coated and dried using a doctor blade on a transparent electrode-equipped substrate that had been patterned with predetermined electrodes using ITO or the like (thickness: 15 μm). A true melt adhesive was applied as a sealant to the peripheral edge of this substrate using a hot melt dispenser. This substrate and the other substrate on which predetermined electrodes had been patterned using ITo or the like were bonded together at predetermined positions, and heated and pressed to produce a liquid crystal display panel.

The above liquid crystal display panel was subjected to a humidity resistance test for 500 hours at 60° C. and 195% humidity.

The resistance value when 50V was applied was 4.3 x 109 before the test.
Ω was 4.2×10 9 Ω after the test, and did not change at all.

As a comparative example, a polymer-dispersed liquid crystal was sandwiched between two substrates, and then the periphery of the substrates was sealed with epoxy resin to produce a liquid crystal display panel, which was resistant to humidity for 500 hours at 60°C and 195% humidity. A sex test was conducted.

The resistance value when 50V was applied was 5.4 x 109 before the test.
The resistance was 3.9×10'Ω after the test, which was a significant decrease in resistance.

〔Effect of the invention〕

In the liquid crystal display panel of the present invention, an adhesive is applied to the peripheral edge of at least one substrate in advance, and then the other substrate is overlapped and sealed, so that hygroscopicity is small and long-term signal performance can be improved.

Patent applicant: Ube Industries Co., Ltd.

Claims (1)

[Claims] A liquid crystal display panel consisting of two substrates provided with transparent electrodes and a medium layer in which liquid crystal is dispersed in the medium, the medium layer being sandwiched between the two substrates so that the transparent electrode surfaces face each other. 1. A method for manufacturing a liquid crystal display panel, comprising forming an adhesive layer on the peripheral edge of at least one of the substrates in advance, and then overlapping and sealing the two substrates.