JPS60181730A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent disturbance of orientation of liquid crystal molecules near a sealant without lowering sealing strength by using a specified modified epoxy one-component type adhesive for both base plates each using a polyimide film as a liquid crystal orienting film to fabricate a cell. CONSTITUTION:A display electrode 3 and a backside electrode 4 are formed on the inside of both of a front base 1 and a back base 2 opposite to each other, and both electrodes 3, 4 are coated with a polyimide resin to form a liquid crystal orienting films 5. The surrounding part of the bases 1, 2 are fabricated by using as a sealant a modified epoxy resin prepared by graft polymerizing a silicone resin with a bisphenol A type resin, and as a hardening agent a modified epoxy one-component type adhesive using adipic acid dihydride or the like so as to prevent disturbance of the liquid crystal molecules near and in contact with the sealant 6. The films 5 and the sealant 16 are in contact with each other or they are partly overlapped each other, thus permitting the disturbance of the liquid crystals to be prevented and a liquid crystal display device good in quality to be obtained.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a liquid crystal display, and particularly relates to a front substrate and a rear substrate each coated with a liquid crystal alignment film, which are coated with a sealing material at a constant interval of 5 to 15 μm. The present invention relates to a liquid crystal display that uses a special sealant to improve its performance, without weakening the adhesive strength and without disturbing the orientation of liquid crystal molecules in the vicinity of the sealant.

[Technical background of the invention and its problems]

A typical liquid crystal display has a structure as shown in FIG.

That is, a display electrode (3) and a back electrode 1 (4) made of a transparent electrode material are formed on the mutually opposing inner surfaces of a front substrate (1) and a back substrate (2), respectively, and these electrodes f3) (4) are formed. A polyimide resin, which is a liquid crystal aligning material, is applied to the top of each layer to form a liquid crystal aligning film (5). The front substrate (1) and the rear substrate (2) having such a configuration are assembled using a sealing material (6) at the peripheral edge so as to have a constant interval of 5 to 15 μm, and liquid crystal is injected and sealed into this constant interval. to complete the liquid crystal display.

However, when using bisphenol resin, which has been commonly used for sealing materials (6), and using fatty acids or aromatic amines as a curing agent, or when diaminophenylmethane or the like is used as a curing agent for phenol novolak resin, When using a so-called two-component poxy resin adhesive, the liquid crystal alignment film (5) and the sealing material (6) come into contact with this sealing material (6) as shown in FIG. 05 to 2 to prevent the alignment of liquid crystal molecules in the peripheral area from being disturbed and to prevent the adhesive strength of the sealing material (6) from decreasing.
It was necessary to provide an interval of approximately

For this reason, in the manufacturing process of liquid crystal displays, it is extremely important to keep the distance between the liquid crystal alignment film (5) and the sealing material (6) approximately 0.5 to 2-2. Not only was the application of the two-component poxy resin adhesive extremely slow, but there was also the problem that the liquid crystal display tended to be large.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problem, and even if the liquid crystal alignment film and the sealing material are in contact with each other or in a structure in which a part of the sealing material is overlapped, the adhesive strength of the sealing material is not weakened.
Another object of the present invention is to provide a liquid crystal display device that does not disturb the orientation of liquid crystal molecules in the vicinity of contact with the sealing material.

[Summary of the invention]

That is, the present invention uses a modified epoxy resin obtained by graph-polymerizing a silicone resin with a bisphenol A type resin, and adipine as a curing agent. It is assembled using a modified epoxy thread one-component adhesive using acid dihydrazide or a similar compound, and is designed to prevent disordered orientation of liquid crystal molecules in the vicinity of contact with the sealing material. The liquid crystal aligning film and the sealing material are in contact with each other, or have a structure in which a portion of the liquid crystal alignment film and the sealing material are combined with each other.

[Embodiments of the invention]

Next, one embodiment of the liquid crystal display of the present invention will be described with reference to FIG. In the figure, the same reference numerals as in FIG. 1 indicate the same parts.

That is, a display electrode (3) and a back electrode (4) made of a transparent electrode material are formed on the mutually opposing inner surfaces of a front substrate (1) and a back substrate (2), respectively. Polyimide resin, which is a liquid crystal alignment material, is applied to form a liquid crystal alignment film (5). The front board with this configuration (
1) and the back Efi + board (2) are covered with sealing material tte on the periphery.
A liquid crystal display device is constructed by assembling the liquid crystals at regular intervals of 5 to 15 μm, and injecting and sealing liquid crystal into the regular interval parts.

Up to this point, it is almost the same as a conventional liquid crystal display, but in this example, bisphenol A is used as the sealing material 6).
A modified epoxy resin made by grafting a silicone resin onto an i-resin, and a modified epoxy one-component adhesive using adipic acid dihydrazide or a similar compound as a curing agent.For example, Structbond Es-55 manufactured by Mitsui Toatsu Chemical Co., Ltd.
By using 00, even if a part of the sealing material (t61) is overlapped with the liquid crystal alignment film (5) on the mutually opposing inner surfaces of the front substrate (1) and the back substrate (2), this sealing material [61 It is possible to prevent the alignment of liquid crystal molecules in the vicinity of contact with the liquid crystal molecules from being disturbed, and there was hardly any decrease in adhesive strength.

Next, a specific example will be explained.

The first specific example is when making a cell for a numerical display small shield liquid crystal display used as a display for ordinary industrial meters, etc., using a screen printing method to make a sealing material, Structbond LFS 5500, into a Q, 3 am width. After printing on the front substrate and drying the printed substrate in a dry open at 90°C for 30 minutes to completely remove the solvent contained in the sealant, apply a pressure of 100g/c+n'' to the back side. It is adhered to the substrate with a gap of 7 μm, and baked at 180° C. for 60 minutes to harden the sealing material, and a liquid crystal display cell is assembled.

In the second specific example, when making a dot matrix type large liquid crystal display cell mainly used as a display device for hand belt computers, etc., Structbond ES-5500, which is a seal strip, is printed on the front substrate by screen printing. The printed board was dried at 90°C for 60 minutes in a dry open oven to completely remove the solvent contained in the sealant.
: 1+Apply any pressure to adhere to the outer substrate with a gap of 10 μm, bake at 180° for 90 minutes to harden the sealing material, and assemble a cell for a large liquid crystal display.

A liquid crystal display was assembled by injecting and fixing '1'N type liquid crystal into the liquid crystal display cell and the large liquid crystal display cell of the two specific examples mentioned above, and then heated to a high temperature of 80''O and a humidity of 90℃.
A high-humidity test and an ultraviolet irradiation test were conducted, but no abnormalities occurred in either case, and in particular, no disturbance in the alignment of liquid crystal molecules near the area in contact with the sealing material was observed. In addition, the adhesive strength of the sealing materials all showed a high adhesive strength of 40 F-y/cnF or more, and this adhesive strength showed almost no change in the high temperature, high humidity test, and ultraviolet irradiation test.

In the above-mentioned embodiment, the liquid crystal alignment film and a part of the sealing material were combined into one structure, but the structure is not limited to this.
Of course, they may be spaced apart to the extent that they touch each other or on the same line as in the conventional case.

[Interchangeable invention]

As described above, according to the present invention, it is possible to prevent the orientation of liquid crystal molecules in the vicinity of contact with the sealing material from being disturbed.
Therefore, it is possible to provide a liquid crystal display device with good quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of a conventional liquid crystal display, and FIG. 2 is an explanatory cross-sectional view of an embodiment of the liquid crystal display of the present invention. 1.Front substrate 2.Back substrate 3.Display electrode 4..Back electrode 5..Liquid crystal alignment film 6,16 Seal material agent Patent attorney Inoue -Male

Claims (2)

[Claims] (1) A front substrate and a rear substrate each coated with polyimide resin as a liquid crystal alignment film, a modified epoxy resin obtained by graft polymerizing silicone resin to bisphenol A5 resin as a sealing material, and adipic acid dihydrazide or similar metal material as a curing agent. Modified epoxy system used 1
A patented liquid crystal display that is assembled using a liquid adhesive and is designed to prevent the alignment of liquid crystal molecules in the vicinity of contact with a sealing material from being disturbed. (2) Claim 1 characterized by a layer having a structure in which the liquid crystal alignment film and the sealing material are in contact with each other or are partially overlapped.
The liquid crystal display described in TL No. 1.