JPH03220525A - lcd display panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to 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]

In a conventional method for sealing a liquid crystal display panel, the peripheral edges of two substrates are sealed in advance with a sealant, liquid crystal is filled through an injection hole, and then the injection hole is closed.

This method cannot be used for polymer-dispersed liquid crystal display panels, and a method has been adopted in which a polymer-dispersed liquid crystal is sandwiched between two substrates and then the peripheral edges of the substrates are sealed with 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, such as a decrease in contrast ratio, 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 a liquid crystal display panel that is sandwiched between two substrates so that the transparent electrode surfaces face each other, the sealing material that seals the periphery of the substrate is made by adding unsaturated carboxylic acids to a hydrocarbon resin whose main component is polyolefin. The present invention relates to a liquid crystal display panel characterized by:

The sealing material of the present invention is made by adding unsaturated carboxylic acids to a hydrocarbon resin containing polyolefins as a main component. Specific examples of the hydrocarbon resin mainly composed of polyolefins used in the present invention include homopolymers of ethylene or polymers of ethylene and other α-olefins such as propylene, butene, pentene, hexene, and heptane. Mention may be made of block or random copolymers. In addition, homopolymers of propylene or other α-polymers such as ethylene, butene, pentene, hexene, heptane, etc.
- Binary or more block or random copolymers with olefins can be mentioned.

Specific examples of unsaturated carboxylic acids added to hydrocarbon resins containing polyolefins as main components include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and their metal salts such as sodium and magnesium. be able to.

These can also be used in combination of two or more types.

Examples of methods for adding unsaturated carboxylic acids to hydrocarbon resins mainly composed of polyolefins include mixing polyolefins, unsaturated carboxylic acids, and organic peroxides, heating and melting the mixture, and reacting the mixture; A method of reacting in a solvent, etc. can be used. The amount of unsaturated carboxylic acid to be used for a hydrocarbon resin mainly composed of polyolefins is IX10-b to 1x10-3 mol, especially lXl0-5 to 1x10-3 mol per gram of hydrocarbon resin mainly composed of polyolefins. 5X10-' moles are preferred.

Further, by adding a filler to the sealing material and applying and sealing the sealant, moisture resistance can be further improved. Specific examples of fillers include inorganic fillers such as powdered, flaky, and fibrous glass, calcium carbonate, tackle, and mica, and polytetrafluoroethylene and ethylene-47.
Fluorinated tyrene copolymer resin, vinylidene fluoride resin, 3
Examples include fluororesin powders such as fluorinated chlorinated ethylene resins. The usage ratio of the filler to the sealing material is 5 to 50 parts by weight, particularly 10 parts by weight, per 100 parts by weight of the sealing material.
~50 parts by weight is preferred.

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
lymer Preprints, Japan vol.
, 37. No. 8.2450 (1988)).

〔Example〕

The present invention will be explained in further detail with reference to production examples below.

Production example 1 Melt index (MI) 2.0 g/l 0 minutes (measurement temperature 190°C), density 0.919 g/c+fl
, melting point 123″C1 molecular weight distribution (Mw/Mn) 3, butene-1 content 4% by weight linear low density polyethylene (LL
DPE) and 0.3X1 for this LLDPEI g
0-' moles of maleic anhydride and 0.096XIO-'
Mol of t-butyl peroxide was mixed in a Henschel tank mixer, and the resulting mixture was put into a single extruder (screw diameter: 50 mm, L/D = 24) and heated at 200''C under a nitrogen atmosphere. and melt-kneaded with a residence time of about 1 minute to produce maleic acid-modified polyethylene (maleic acid-modified cotton-like low-density polyethylene).

The maleic acid-modified polyethylene (modified product) obtained was L
0.29 x 10 mol of maleic anhydride was graft-polymerized to LDPElg, Mll, 5g/10
minute, density 0.919 g/C'lll, and melting point 123
'C.

On the other hand, 10% PVA aqueous solution, liquid crystal, dichroic dye [PVA
:Liquid crystal = 1:3.5 (weight ratio), dichroic dye is 3 parts of liquid crystal
% by weight] 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). This substrate was bonded to another substrate on which predetermined electrodes had been patterned using ITO or the like in advance so as to match each other at a predetermined position to produce a liquid crystal display panel.

The maleic acid-modified polyethylene was applied to the periphery of the bonded substrates using a hot melt gun to seal the liquid crystal display panel.

The above liquid crystal display panel was subjected to a moisture resistance test for 500 hours at 50° C. and 195% humidity.

The resistance value when 50V was applied was 7.3 x 109 before the test.
Ω was 5.6×10 9 Ω after the test, and did not change at all.

Production Example 2 A liquid crystal display panel was produced in the same manner as Production Example 1 except that a conventionally known two-component epoxy resin adhesive was used as the sealing material, and it was resistant to humidity for 500 hours at 50°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 after the test was 1.58×10 9 Ω, which was a significant decrease in resistance.

Production Example 3 Calcium carbonate (Whiten SSB Red, average particle size 1.25 μm, specific surface area 1.85 square meters/g, Shiraishi Calcium) was added to the maleic acid-modified polyethylene produced in Production Example 1 at 75:25 (parts by weight). A liquid crystal display panel was manufactured using a sealing material mixed at a ratio of 50°C1.
A 500 hour moisture resistance test was conducted under the condition of 95% humidity.

The resistance value when 50V was applied was 8.2×109 before the test.
Ω, 6 after the test. It was 1×10′Ω.

〔Effect of the invention〕

Since the liquid crystal display panel of the present invention uses a hydrocarbon resin containing polyolefins as a main component to which unsaturated carboxylic acids are added as a sealing material, it has low hygroscopicity and can improve long-term reliability.

Further, when the sealing material of the present invention is used, the peripheral edge of the substrate can be sealed in a short time, and the adverse effect on the liquid crystal due to heating in the sealing process is small.

Claims (1)

[Claims] (1) Consisting of two substrates on which transparent electrodes were arranged and a medium layer in which liquid crystal was dispersed in the medium, the medium layer was sandwiched between the two substrates so that the transparent electrode surfaces faced each other. 1. A liquid crystal display panel characterized in that a sealing material for sealing a peripheral edge of a substrate is made of a hydrocarbon resin containing polyolefins as a main component to which unsaturated carboxylic acids are added.