JPH0296119A - Liquid crystal display device made of film substrate and production thereof - Google Patents

Abstract

PURPOSE:To provide the display device which is excellent in uniform space setting and durability and to prevent the impairment of the characteristics intrinsic to a film by using two specific powders as spacers. CONSTITUTION:The spacers 1, 2 consist of the spherical or fibrous hard powder 1 and the cylindrical or hemispherical powder 2 only one flat surface of which is adhered to the film substrate. The powder 1 includes, for example, spherical powders such as glass beads, silica beads, alumina powder, and crosslinked polystyrene beads and cut powders of glass fibers or carbon fibers, etc. The powder 2 is the powder having adhesive power and consist of a thermoplastic resin and is more specifically exemplified by hot melt adhesive resins consisting of polyester, nylon, vinyl acetate, etc. The high gap accuracy and improved durability are obtd. in this way without impairing the resilience which is the characteristics of the film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a film substrate liquid crystal display device and a method for manufacturing the same, and more specifically, to a film substrate liquid crystal display device and a method for manufacturing the same, and more specifically, to a film substrate liquid crystal display device and a method for manufacturing the same. The present invention relates to a film substrate liquid crystal display device and a manufacturing method thereof.

[Prior Art] Conventionally, inorganic particles such as glass beads and silica beads, and organic particles such as crosslinked polystyrene beads have been used as spacers for the purpose of making the gap in a liquid crystal display device constant. However, when these spacers are used, since the substrate is a film, the spacers easily move due to bending or light pressure, resulting in color unevenness.

As a method to solve these problems, JP-A-58-9
Japanese Patent No. 7023 proposes a film substrate liquid crystal display device having a point bonding structure by using the bead-like spacer and powder or fibrous adhesive.

[Problems to be Solved by the Invention] However, although this method has the effect of suppressing the movement of the spacer, the flexibility of the film substrate liquid crystal display device is extremely high because the upper and lower substrates are firmly adhesively fixed. There is a problem in that the original characteristics of the film substrate are significantly deteriorated.

The present invention seeks to solve such problems, and necessarily includes:
It is an object of the present invention to provide a film substrate liquid crystal display device which has uniform gap setting and excellent durability, and which does not impair the original characteristics of the film.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

[(1) A pair of film substrates having a transparent electrode and an alignment film on the inside are arranged facing each other with a predetermined gap between them with a spacer in between,
A film substrate liquid crystal display device in which liquid crystal is sealed in the gap, characterized in that the spacer is composed of the following A and B.

A8 Spherical or fibrous hard powder.

B. A powder mainly composed of a thermoplastic resin, which has a cylindrical or hemispherical shape, and whose flat surface is adhered to only one of the pair of films.

(2) Claim (2) characterized in that after scattering spherical particles made of the powder component B on one substrate, the particles are adhesively fixed by heating, and then the other substrate is brought into close contact with the other substrate.
1) A method for manufacturing a film substrate liquid crystal display device as described above.

(3) Sprinkle spherical particles made of the powder component B onto one substrate, place the other substrate in close contact with each other, and heat and press to melt and compress the particles to a predetermined gap between the substrates. 2. The method of manufacturing a film substrate liquid crystal display device according to claim 1, wherein the adhesive surface between the particles and one of the film substrates is peeled off. ” The present invention will be explained in more detail below.

The spacer used in the present invention consists of a spherical or fibrous hard powder (hereinafter referred to as "A powder") and a cylindrical or hemispherical powder (hereinafter referred to as "A powder") whose only flat surface is adhered to the film substrate. (referred to as B powder).

Examples of powder A include spherical powders such as glass beads, silica beads, alumina powder, and crosslinked polystyrene beads, and cut powders such as glass fibers or carbon fibers. These A powders are hard and have the function of keeping the gap substantially constant.

Powder B is a powder that has adhesive ability and is made of a plastic resin. Specific examples thereof include hot melt adhesive resins made of polyester, nylon, vinyl acetate, and the like. In particular, polyester with well-balanced heat resistance, adhesiveness, and liquid crystal resistance is preferred. Further, cylindrical shape means the shape shown by 2 in FIG. 2, for example, which is made up of two parallel planes and side surfaces, and hemispherical shape means, for example, the shape shown by 2 in FIG. 1. .

These B powders satisfy the dimensions shown by the following formula (I).

Q<r1≦2D, 1/4[)≦r2≦2D...
... (■) In the formula, D is the thickness of the liquid crystal layer, rl and r2 are the radius of the contact part with the film substrate, rl is the radius of the non-adhesive part, r2 is the radius of the adhesive part If rl and r2 exceed 2D, their presence will be noticeable in the liquid crystal cell, which may lead to a decrease in image quality, which is not preferable.Also, if r2 of the plane bonded and fixed to the substrate is
If it is less than D, the adhesive force with the substrate will be insufficient, which is not preferable.

Further, the thickness of the liquid crystal layer of a film substrate liquid crystal display device is generally 2 to 10 μm, and the powders A and B in the present invention have a diameter or height that allows them to fit into the gap therebetween.

The spacers used in the present invention have a combined density of 0.5 to 500 pieces/mm2, preferably 10 to 20 pieces/mm2 of A and B powders.
It is preferable to scatter within the range of 0 pieces/+ntn2. If the amount of spraying is less than 0.5 particles/mm2, the function as a spacer cannot be fully expressed.

Furthermore, if the amount of spraying exceeds 500 particles/mm2, the image quality of the liquid crystal display cell will deteriorate, which is not preferable.

The composition ratio of the A and B powders is such that the B powder accounts for 10% or more, preferably 25% or more of the total number of spacers. If the B powder content is less than 10%, the amount of powder adhering to the substrate will decrease, which is undesirable because the mechanical strength and durability of the film liquid crystal display device will decrease.

As the film substrate of the film substrate liquid crystal display device of the present invention, films of polyether sulfone, polyethylene terephthalate, polysulfone, polycarbonate, etc. are preferably used.

Next, a method for manufacturing the film substrate liquid crystal display device of the present invention will be described.

The spacers are distributed on the substrate by dry and/or wet methods. The A powder and the 8 particles can be mixed and sprayed at the same time, or they can be sprayed separately on the same substrate or on different substrates.

The present invention is characterized by the B powder being adhesively fixed to only one of the substrates, and by the following two methods:
It can be glued and fixed on only one side.

The first method is to spray spherical particles (hereinafter referred to as 8 particles) made of the B powder component onto one substrate, and then heat the substrate on which the 8 particles have been spread using a hot air oven, heating furnace, or hot plate. to adhesively fix the particles,
This is a method in which the other substrate is brought into close contact with the other substrate after cooling to room temperature.

In this case, the 8 particles are particles whose diameter is at least larger than the thickness of the liquid crystal layer, and when these particles are heated together with the substrate, they are melted and become hemispherical BiI powder. Here, if the 8 particles are not spherical but fibrous or amorphous powder obtained by mechanical crushing, large particles are required to obtain sufficient adhesion, and therefore, the size of the liquid crystal display cell increases. This will lead to a deterioration in image quality, and furthermore, if the powder is irregularly shaped, it is difficult to make the particle size uniform by classification or the like.

In addition, considering the heat resistance of the substrate film, the heating temperature is preferably 1B, ℃ or less, and roughly 1B.
It is preferably 50'C or less.

Within this range, in order to satisfy Equation (1) above, consider the thermal properties of the resin used as the 8 particles, that is, the glass transition temperature, thermal pour point, softening point, melting point, etc. It is important to select heat treatment conditions appropriately.

Generally, the Act> and 8 particles are dispersed onto the substrate by dry and/or wet methods. In addition, in film liquid crystal display devices, a sealant is applied to the edges of the film substrate by screen printing, etc., but it is best to spray the 8 particles onto a substrate different from the substrate on which the sealant is applied. preferable. Powder A may be sprinkled on either substrate, and when it is sprinkled on the same substrate as 8 particles, it may be mixed with 8 particles and sprayed at the same time, or each may be sprayed separately, or the 8 particles may be heat-treated. It may be sprayed after it has been applied.

Next, the second method is to spread 8 particles onto one substrate, place the other substrate in close contact with each other, and then apply heat and pressure treatment to melt and compress it to a predetermined gap between the substrates. In this method, the particles are adhesively fixed between the particles, and then the adhesive surface of either the particles and the substrate is peeled off.

In this case, as in the first method, the 8 particles are particles whose diameter is at least larger than the thickness of the liquid crystal layer, and when these particles are melted and compressed by the rain plate, they become cylindrical B powder. .

Furthermore, in this method, the 8 particles may be sprinkled on either substrate, and the A powder may also be sprinkled on either substrate.

8 The method of peeling off the adhesive surfaces of either the particles and the substrate is to deform the side substrates into an arch shape in the same direction before or after the liquid crystal is filled into the cell, and then apply tension to each adhesive surface. Examples include methods of applying stress and compressive stress. In addition, a type of shear stress is applied to the cell after the liquid crystal has been filled in by passing it through a rubber roller with a gap narrower than the cell thickness (either one made of rollers or one made of rollers and a flat surface is fine). This method is particularly preferred because it has advantages such as continuous processing, precise control of stress, and excellent reproducibility. .

Furthermore, in the present invention, by combining the first method and the second method, it is also possible to obtain a film substrate liquid crystal display device having eight cylindrical particles and eight hemispherical particles.

[Example] Examples of the present invention are listed below, but the present invention is not limited thereto.

Synthesis Example 1 (Synthesis Example of 8 Particles) 50 parts by weight of chloroform was added to 100 parts by weight of polyester resin (trade name: 1chemito ni 1294 manufactured by Toshi ■).
A polymer solution was obtained by dissolving. The polymer solution was heated at room temperature for 60 min.
While stirring at a stirring speed of 0 rt) m, 4% concentration of polyvinyl alcohol (trade name "GOHSENOL EG-05J") was added.
Parts by weight of aqueous solution B (manufactured by Nippon Gosei Kagaku Co., Ltd.) were continuously added over 5 minutes to transform the initial W10 type emulsion into a final O/W type dairy emulsion. After adding 70 parts by weight of water to the emulsion, it was heated at 300 rl) III for 60' while stirring.
After increasing the temperature to
Spherical polyester resin particles with a particle size variation rate of 12% in μm were obtained.

Example 1 The spherical polyester resin particles obtained in Synthesis Example 1 were dispersed in Freon containing 0.5 wt% ethanol on a polyether sulfone film substrate on which an ITO film and an orientation-treated polyimide alignment film were formed, and a wet process was carried out. Spread. The amount of spraying was 50 particles/mm2. Next, the film substrate on which the particles were sprinkled was placed in a hot air oven at 150'C for 4 hours.
The particles were adhered and fixed to the substrate by heat treatment for 0 minutes. As a result of scanning electron microscopy (32M observation), the particles had a hemispherical shape, a height of 8 μm, and a radius of the adhesive surface with the substrate of 3.9 μm.

Next, a sealant was screen printed on the peripheral edge, and 50% crosslinked polystyrene particles (monodisperse particles with a particle size of 8 μm) were added.
Another polyether sulfone film substrate that had been wet-sprayed at a density of 200
It was treated at 120'C for 2 hours under a load of ';j/cm to firmly bond the upper and lower substrates and the sealant.

Next, a film substrate liquid crystal display device having a uniform liquid crystal layer thickness was obtained by injecting liquid crystal into the empty cell and sealing the injection port.

FIG. 1 shows a longitudinal cross-sectional view of the film substrate liquid crystal display device of Example 1. In Figure 1, 1 is a crosslinked polystyrene particle, 2
3 indicates a polyester resin powder, 3 indicates a liquid crystal, 4 indicates a film substrate, and 5 indicates a sealant.

Example 2 Cross-linked polystyrene particles (particle size 8μ
Monodispersed particles of 50 m2/mm2 were wet-sprayed, and then the spherical polyester resin particles obtained in Synthesis Example 1 were dispersed in Freon containing 0.5 wt% of ethanol.
Wet spraying was performed so that the number of particles/mm2 was 0.

Next, another polyether sulfone film substrate was placed in close contact with each other to face each other to form a 200';j/cr? under load of r1
It was treated at 50° C. for 2 hours to bond the upper and lower substrates, the polyester resin particles, and the sealant. As a result of SEX observation,
The spherical polyester resin particles took the form of a spheroid with the short axis flattened at the top and bottom, had a height of 8 μm, and had a radius of 4.6 μm at the bonding surface with the upper and lower substrates.

Next, liquid crystal was injected into the empty cell and the injection port was sealed to obtain a cell having a uniform liquid crystal layer thickness. Further, the cell was passed several times between rubber rolls having a clearance of 0.15 M and a Shore A hardness of 60 to apply shear stress, thereby obtaining a film substrate liquid crystal display device in which the adhesive surface to one of the substrates was peeled off.

FIG. 2 shows a longitudinal cross-sectional view of the film substrate liquid crystal display device of Example 2.

Comparative Example 1 All operations were performed in the same manner as in Example 2, except that spherical polyester resin particles were not used, crosslinked styrene particles were dispersed at 100 particles/mm2, and the process of passing between rubber rolls was not performed. A liquid crystal display device was obtained.

Comparative Example 2 All operations were performed in the same manner as in Example 2, except that the cells were not passed between rubber rolls (that is, both the upper and lower substrates and the polyester resin particles were adhesively fixed). A liquid crystal display device was obtained.

Using the film substrate liquid crystal display devices obtained in Examples 1 and 2 and Comparative Examples 1 and 2, the distribution of substrate gap (minimum to maximum), pencil rubbing test (number of times color unevenness occurred and did not return to its original state) ) and the flexibility of the cell were evaluated. The results are shown in Table 1.

As shown in Table 1, the film substrate liquid crystal display device of the present invention was found to be excellent in gap accuracy, durability, and flexibility.

n〉 Q: 100 times or more △: 50 to 100 times ×: 50 times or less [Effects of the invention] The film substrate liquid crystal display device of the present invention has high gap accuracy without impairing the flexibility, which is a feature of the film.
Moreover, it has excellent durability.

[Brief explanation of the drawing]

FIG. 1 shows a longitudinal sectional view of a film substrate liquid crystal display device according to Example 1 of the present invention. FIG. 2 shows a longitudinal sectional view of a film substrate liquid crystal display device according to Example 2 of the present invention. 1: Cross-linked polystyrene particles, 2: Polyester resin powder, 3: Liquid crystal, 4: Film substrate, 5: Sealant Figure 1 Patent applicant Toshi Co., Ltd. Civility Figure 2

Claims (4)

[Claims] (1) In a film substrate liquid crystal display device in which a pair of film substrates having a transparent electrode and an alignment film inside are arranged facing each other with a predetermined gap between them with a spacer in between, and liquid crystal is sealed in the gap, the spacer is , B. A film substrate liquid crystal display device comprising: . A. Spherical or fibrous hard powder. B. A powder mainly composed of a thermoplastic resin, which is cylindrical or hemispherical, and whose plane is adhered to only one of the pair of films. (2) The film substrate liquid crystal display device according to claim (I), wherein the powder B satisfies the dimensions expressed by the following formula (I). O<r_1≦2D, 1/4D≦r_2≦2D...
・(I) (where D is the thickness of the liquid crystal layer, r_1 and r_2
is the radius of the contact part with the film substrate, r_1 is the radius in the non-bonded part, and r_2 is the radius in the bonded part. ) (3) Claim (3) characterized in that after scattering spherical particles made of the powder component B on one substrate, the particles are adhesively fixed by heating, and then the other substrate is brought into close contact with the other substrate.
1) A method for manufacturing a film substrate liquid crystal display device as described above. (4) Sprinkle spherical particles made of the powder component B onto one substrate, place the other substrate in close contact with each other, and heat and press the particles to melt and compress the particles to a predetermined gap between the substrates. 2. The method of manufacturing a film substrate liquid crystal display device according to claim 1, wherein the adhesive surface between the particles and one of the film substrates is peeled off.