JPS6286331A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To make it possible to maintain the function of the liquid crystal at a high temp. for long periods by applying an organic spacer made of fine particles having a uniform particle size to the titled element. CONSTITUTION:The fine particles having 1-10mum uniform particle size and <=0.3mum standard deviation of the particle size distribution are preferable to the use as the organic spacer 1, with regard to adjusting a gap with a high accuracy. The method of producing the fine spherical and uniform particles which has the prescribed particle size and particle distribution and also has a solvent resistance without the necessity of a classification treatment, is the method of preparing a mixture contg. 100-3,000pts.wt. the total of a crosslinking monomer and a non-crosslinking monomer and 100wt.pts. the fine particles of a crosslinking high polymer having 0.4-5mu the particle size of a swelled monomer and 0.2mum the standard deviation of the particle size distribution in a dispersed state, and then of absorping the monomer in the fine particles made of the crosslinking high polymer followed by polymerizing it in the presence of a polymerization initiator.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention has excellent liquid crystal resistance, heat resistance, and suppression resistance, and can reduce the thickness of the liquid crystal layer in a liquid crystal display element. The present invention relates to a liquid crystal display element in which the gap between transparent electrode substrates is regulated by an organic spacer made of modified crosslinked polymer fine particles that can be adjusted with high precision.

Since the thickness of the liquid crystal layer in a conventional liquid crystal display element, that is, the gap between the transparent electrode substrates, has a large effect on the optical characteristics of the element, spacers are entirely provided in order to adjust the gap with high precision. The main intervening methods include placing it on a transparent electrode substrate, adding it to a sealing material for a liquid crystal enclosure, and using both of these methods together.

The performance required for such a spacer is that it has a solvent-resistant metal that does not dissolve or swell with the liquid crystal or sealant, and that it has a heat treatment temperature (100 to 100℃) when curing the sealant.
Examples include having heat resistance that can withstand temperatures (generally 200° C.), and having strength that can withstand suppression treatment of the substrate.

Conventionally, examples of spacer gold pieces made of organic materials include Japanese Patent Application Laid-open Nos. 55-38567, 57-70522, 57-84432, and 57-189117.
Publication No. 57-210323, Utility Model Application No. 55-1
16318 and the like have been proposed.

These organic spacers are made of glass fiber,
Damage to the substrate or its transparent electrode when pressing the substrate due to the hardness, non-sphericity, etc. of inorganic spacers made of metal oxide powder, etc., and difficulty in adjusting the gap between the substrates with high precision. The purpose is to overcome problems such as sexuality.

Problems to be Solved by the Invention However, conventional organic spacers cannot achieve satisfactory gap accuracy unless they are classified after production to make the particle size uniform. In addition to the problem of obtaining spacers, which requires less time and labor, there is also the serious problem of not satisfying all of the strength requirements such as liquid crystal resistance, solvent resistance, heat resistance, and compression resistance, which makes it difficult to put into practical use. From my point of view, it was not satisfactory.

Means for Solving the Problems The present inventors have overcome the above-mentioned problems, and have developed a method that allows the thickness of the liquid crystal layer in a liquid crystal display element to be adjusted accurately and arbitrarily, and that does not cause any adverse effects such as damage to the substrate due to suppression. As a result of extensive research to develop an organic spacer with excellent liquid crystal resistance, heat resistance, and suppression resistance, we have developed a product that is made by modifying crosslinked polymer fine particles with crosslinkable and non-crosslinkable monomers. They discovered that the purpose could be achieved by using fine particles, and came up with the present invention. That is, the present invention provides a method in which a liquid crystal is sealed between a transparent electrode substrate provided with a transparent electrode and an alignment film, and The gap between the transparent electrode substrates is filled with an organic system consisting of spherical, solvent-resistant, uniformly sized fine particles obtained by modifying cross-linked polymer fine particles through a polymerization process using a non-cross-linking monomer and a cross-linking monomer. The present invention provides a liquid crystal display element that is regulated by spacers.

By using an organic spacer made of fine particles with a uniform particle size as described in the operation, the gap between the transparent electrode substrates in a liquid crystal display element can be adjusted with precision, and the elution of the spacer component that impairs the function of the liquid crystal can be avoided for a long time or at high temperatures. Even if it is placed down, it is prevented and the function of the liquid crystal is maintained. Furthermore, the spacer is not melted or destroyed by heating or pressing during device fabrication, and highly accurate adjustment of the gap can be achieved.

Examples of Constituent Elements of the Invention The organic spacer in the present invention has a particle size of 1 to 1
Fine particles with a uniform particle size of 0 μm and a standard deviation of particle size distribution of 0.3 μm or less are preferably used from the viewpoint of highly accurate adjustment of the gap.

A method for obtaining spherical, solvent-resistant, uniformly sized fine particles having such a particle size and particle size distribution without the need for classification treatment is as follows:
For example, the following method can be cited.

That is, the total amount of the crosslinking monomer and non-crosslinking monomer is 100 to 3000 parts by weight, and the particle size is 04 to 5 μm and the standard deviation of the particle size distribution is 0.2 μm.
By preparing a mixed solution containing 100 parts by weight of crosslinked polymer fine particles of m or less in a dispersed state, absorbing the mJ monomer into the crosslinked polymer fine particles and polymerizing them in the coexistence of a polymerization initiator. Obtainable.

In addition, the crosslinked polymer fine particles used here are obtained by dispersing a non-crosslinking monomer and a crosslinking monomer in a dispersion medium containing or not containing an emulsifier, and in the coexistence of a polymerization initiator soluble in the dispersion medium. It can be easily obtained by applying a normal polymerization method to polymerizing. In this case, a non-emulsifying polymerization method that does not use an emulsifier is preferable since the particle size of the polymer obtained is larger. In addition, the polymer in the emulsion obtained by the usual emulsion polymerization method is used as a seed particle, and it is mixed with a dispersion medium, a crosslinking monomer, a non-crosslinking monomer, and an emulsifier in the amount necessary to stabilize the polymerization reaction. (Surface tension is 55 dyn/am
It is preferable that the above is achieved. ) and seed polymerization by adding a polymerization initiator or 2 times as necessary.
It can also be obtained by repeating the application several times to form particles larger than the initial seed particles. Particles obtained by this method have a more uniform particle size distribution and can therefore be preferably used in the present invention. In this case, it is preferable that the non-crosslinkable monomer be one having a glass transition point of 80° C. or higher, and the crosslinkable monomer preferably be one having an ethylenic double bond k of 2 or more, such as divinylbenzene. used.

The crosslinked polymer fine particles that can be swelled with the monomers used are used in proportions such that, for example, non-crosslinking monomers are 99 to 99.95% by weight and crosslinking monomers are 1 to 0.05% by weight. This can be achieved by mixing and copolymerizing by the above-mentioned method such as emulsion polymerization method. The swelling degree of the crosslinked polymer fine particles obtained by copolymerizing at this usage ratio is usually 8 to 100, which is defined as the volume of the particles after swelling compared to before swelling. It is suitable for If the proportion of the crosslinking monomer used is too small, particles with an excessive degree of swelling will be obtained, and the objectives of the present invention will be difficult to achieve, such as the solvent resistance of the finally obtained uniform particle size particles being insufficient3.゜On the other hand, if the proportion of crosslinkable monomer used is too large, a product with too low degree of swelling (excessive crosslinking density) will be obtained, resulting in the polymerization when providing the crosslinked polymer in the crosslinked polymer fine particles. In the treatment, the monomer cannot be sufficiently diffused into the fine particles, resulting in insufficient polymerization in the fine particles, and new fine particles are generated in addition to the fine particles, which is undesirable.

Next, the obtained crosslinked polymer fine particles are used to prepare a liquid mixture containing a crosslinkable monomer and a non-crosslinkable monomer in a dispersed state. This mixed solution is usually prepared by adding a polymerization initiator to a dispersion of crosslinked polymer fine particles, especially an aqueous dispersion as an emulsion polymerization solution, and a mixture of a crosslinkable monomer and a non-crosslinkable monomer. This is done by adding . Of course, the preparation method is not limited to this. The mixing ratio is 100 parts by weight of the crosslinked polymer fine particles, and the total amount of both monomers is 100 to 3 parts by weight.
000 parts by weight is suitable. If the mixing ratio of the total weight of both vehicles is less than 100 parts by weight, the obtained uniform particle size fine particles will have insufficient solvent resistance, while if it exceeds 3000 parts by weight, the solvent resistance will be insufficient. This is not preferable because polymerization tends to proceed easily. On the other hand, the blending ratio of the two polymers, that is, the crosslinkable monomer and the non-crosslinkable monomer, is 0.1 to 1 mole of the crosslinkable monomer per mole of the non-crosslinkable monomer, preferably 0. .2 to 0.8 mol is suitable. If the blending ratio of the crosslinkable monomer is less than 0.1 mol, the crosslinking density of the crosslinked polymer formed will be too low, while if it exceeds 1 mo/I/wo, the crosslinking density of the crosslinked polymer will be too high, which is preferable. do not have.

Examples of the monomers that can be used include the same monomers as those used in the crosslinked polymer fine particles described above. At this time, if a crosslinkable monomer that is easily soluble in water is used, the monomer will not effectively penetrate into the crosslinked polymer fine particles, and new particles will often be generated in addition to the fine particles. Those hardly soluble in water can be preferably used in a water dispersion system. Moreover, as non-crosslinkable monomers from the same ground, those that are sparingly soluble in water in the same dispersion system can be preferably used. Therefore, a preferred combination is a combination of a crosslinked polymer that is poorly soluble in water, such as a crosslinked polymer fine particle made of a styrene monomer and divinylbenzene, and a crosslinked polymer.

In this case, the appropriate blending ratio for forming the crosslinked polymer is 50 to 90% by weight of styrene monomer and 50 to 10% by weight of divinylbenzene.

The modification treatment by polymerization is carried out in the presence of a polymerization initiator in a state where the monomer II is absorbed into the crosslinked polymer fine particles. The absorption can be carried out, for example, by adding the mixture of the monomers to a dispersion of crosslinked polymer fine particles and stirring the mixture. At that time, heating may be performed to increase the absorption rate of the monomer, or a water-soluble solvent such as acetone or ethanol (in the case of an aqueous dispersion system) may be added. Alternatively, the monomer may be emulsified in advance and added. In addition, in the method using a solvent, it is preferable to remove the solvent before starting the polymerization.

On the other hand, when a water dispersion system is used as the polymerization initiator, an ordinary oil-soluble radical initiator is preferably used. If it is water-soluble, new particles may be generated in addition to the seed particles, which may cause problems. Note that it is desirable to use the oil-soluble polymerization initiator dissolved in the monomer in an amount of 0.1 to 3% by weight in order to smoothly carry out the polymerization in the crosslinked polymer fine particles.

During polymerization, it is desirable to stabilize the particles using an emulsifier or a polymerization stabilizer, and the appropriate amount of use thereof is such that no new particles are produced in addition to the crosslinked polymer fine particles.

By carrying out the polymerization reaction as described above, the particle size of the crosslinked polymer fine particles modified with a monomer and having a crosslinked polymer gold having a higher crosslink density in the crosslinked polymer fine particles is increased. 1=I Oilm, the standard deviation of the particle size distribution is 0.3 μm or less, excellent sphericity, solvent resistance, and uniform particle size can be obtained.

The uniformly sized fine particles obtained in this way have excellent particle size uniformity and do not require classification treatment, and can be used as a trench in the obtained aqueous dispersion or as a dispersion using other organic solvents. Alternatively, it can be used for practical purposes as it is as a dry powder.

In the liquid crystal display element of the present invention, the gap between the transparent electrode substrates is regulated using the above-described spacer.

As a manufacturing method for a liquid crystal display element, for example, as shown in FIG. 112, powder of an organic spacer 1 is dispersed in a sealing material 2, and then the powder is coated with a transparent electrode 4 and an alignment film 5, such as a glass plate, a dew stick film, or a polarizing film. The transparent electrode substrate 3 is attached on a base material 6 made of a plate or the like by a screen printing method, and another transparent electrode substrate 3 is superimposed on it to suppress it (generally about 1 kg/CI!). Pressure) and heat to harden the sealing material, and then inject liquid crystal 7, or as shown in Figure 3.4, apply a dispersion of organic spacer 1 using a spin code method, etc. and then disperse it. Dry the medium or aerosol/+7'f of organic spacer l:
After spreading the organic spacer 1 over almost the entire surface of the transparent electrode substrate 3, applying the sealing material 2, overlapping and heating other substrates, and applying the liquid crystal 7 in the same manner as described above.
An example of this method is to perform an injection process. Is there an organic spacer almost entirely on the latter substrate? What method should be used to attach it, especially if it is a large one, in terms of the accuracy of the gap in the center? Since it can be measured, it can be advantageously applied to large panels.

Effects of the Invention According to the present invention, a spherical, solvent-resistant organic system consisting of uniformly sized crosslinked polymer fine particles modified by a polymerization process using a non-crosslinking monomer and a crosslinking monomer is produced. Since the 7 baser is used, a liquid crystal display element with excellent gap accuracy between the transparent electrode substrates can be obtained. As a result, an element with excellent performance such as viewing angle characteristics and response characteristics can be obtained.

Furthermore, since the spacer is virtually never melted or destroyed by heating or compression during device fabrication, highly accurate adjustment of the substrate gap can be easily achieved, and the yield rate of liquid crystal display elements with highly accurate gaps can be increased. can be obtained with high efficiency and excellent reliability.

In addition, the spacer has excellent liquid crystal resistance and stability under the element, so that a liquid crystal display element with excellent function maintenance can be obtained.

Examples Reference Example 1 Styrene 3 in which 0.25% of divinylbenzene (% by weight, the same as below) was dissolved in 70 parts of ion-exchanged water in which 6 parts (by weight, the same hereinafter) of IJ (lauryl sulfate) was dissolved.
After dispersing 0 part, the temperature was raised to 70°C under a nitrogen stream while stirring, then 5 parts of ion exchange water in which 0.03 part of potassium persulfate was dissolved was added, and the temperature was maintained at 70°C for 8 hours. A dispersion of polymer particles was obtained. The particle size of this polymer particle is 0,043 μm.The standard deviation of the particle size distribution is 0.01.
It was μm.

Next, part of the dispersed M2O of the obtained polymer particles and 65 parts of ion-exchanged water were mixed and wetted at 70°C, and then 30 parts of styrene in which 25% of divinylbenzene was dissolved was added and stirred for 1 hour. Then, in step b, 5 parts of ion-exchanged water in which 0.03 parts of potassium persulfate was dissolved was added and kept at 70°C for 8 hours, so that the particle size was O,I +49 μm and the standard deviation of the particle size distribution was 0. An aqueous dispersion of 0.127 parts m of polymer particles was obtained. Further, the obtained dispersion was used to obtain an aqueous dispersion of polymer particles having a composition shown in the table L7, which did not undergo bonding.

In this way, the loosely crosslinked i
Dispersion liquid B of crosslinked polymer fine particles with a good particle size distribution,
I got C=i. In addition, the degree of swelling of the fine particles in the dispersion C obtained here with respect to the styrene monomer was 4 (11), which was 15.

Next, add 10 parts of the dispersion of C in the table to 120 parts of ion-exchanged water and polyvinyl alcohol (Kuraray Bobber #420, /7-
After adding 5 parts of a 10% aqueous solution (degree of oxidation: 88%, manufactured by Kuraray Co., Ltd.) and stirring uniformly, benzylic peroxide/L' was added to 60 parts of a monomer consisting of 75% styrene and 259% divinylbenzene.
A total of 0.6 part of the solution was added and polymerized under a nitrogen stream at 60° C. for 4 hours and 80° C. for 5 hours while stirring to obtain a dispersion of fine particles of uniform particle size.

The particle size of the fine particles was 4.50 μm, and the standard deviation of the particle size distribution was 0.15 μm.

Reference Example 2 10 parts of the dispersion of B in the above table, 120 parts of ion-exchanged water and polyvinyl alcohol-A/(Kurare Bobber/1/224,
Saponification degree: 88%, manufactured by Kuraray Co., Ltd.)) After adding 5 parts of a 10% aqueous solution and stirring uniformly, 60 parts of a monomer consisting of 75% of styrene and 25% of divinylbenzene was mixed with benzylic peroxide/L1.
A total of 0.6 part of the solution was added and polymerized under a nitrogen stream at 60° C. for 4 hours and 80° C. for 5 hours while stirring to obtain a dispersion of fine particles of uniform particle size. The particle size of this fine particle is 1.92
The standard deviation of pm and particle size distribution was 0.1211 m.

Example 1 The fine particles obtained in Reference Example 1 were dried using a spray drying method to form a powder, which was then mixed with an all-epoxy adhesive (SE-4500).
0 for sealing material made of epoxy resin (manufactured by Yoshikawa Kako Co., Ltd.)
, 1 weight φ was added and mixed thoroughly, and screen printing was performed on the transparent electrode substrate provided with the rubbed material of the transparent electrode and IML film, and another transparent electrode substrate was superimposed on this and Ikq/a+ was applied under vacuum. ! After crimping at a pressure of
The sealing material was cured by heat treatment for a period of time, and liquid crystal was injected to obtain a liquid crystal display element having the specifications shown in FIG. 1.2.

The gap between the transparent electrode substrates in this device, or its accuracy, was excellent and uniform at 45±O2 μm.

Note that the base material for the transparent electrode substrate has a thickness of 100 μm.
It is made of transparent uniaxially stretched polyethylene terephthalate film.

Example 2 The fine particles obtained in Reference Example 2 were dried using a spray drying method to form a powder, which was dispersed in ethyl alcohol using ultrasonic waves, and the resulting dispersion was prepared using a spin code method in Example 1.
After spraying on the same transparent electrode substrate and the same transparent electrode substrate, Ethyl alcohol fi/f was volatilized.

The number of particles in the obtained substrate is ioo per LCD.
It was about m. Next, a sealing material (same as above) containing 0.1% by weight of the same powder was screen printed on the obtained substrate, and another transparent electrode substrate was superimposed on this, and then treated in the same manner as in Example 1. A liquid crystal display element having the specifications shown in Fig. 3.4 was obtained.

The gap between the transparent electrode substrates in this device, or its accuracy, was excellent and uniform at 1.92±O'' μm.

Incidentally, the element in which the powder is used for the substrate surface 5 and the substrate bonding part of Example 2 is particularly effective when the substrate area is large.

[Brief explanation of drawings]

Figure 1 is a perspective view of a transparent electrode substrate (schematic) attached with a sealant containing organic spacers, Figure 2 is a side cross-sectional view of a liquid crystal display element using the substrate, and Figure 3 is an organic spacer coated on the entire surface. Perspective view of a transparent electrode substrate (schematic) with distributed attachment, No. 4
The figure is a side sectional view of a liquid crystal display element using the substrate. l: Organic spacer 2: Seal material 3: Transparent electrode substrate 4: Transparent electrode 5: Alignment film 6: Base material 7: Liquid crystal

Claims (1)

[Claims] 1. In a liquid crystal display element in which a liquid crystal is sealed between transparent electrode substrates provided with transparent electrodes and an alignment film, and the gap between the transparent electrode substrates is regulated with an organic spacer. , the organic spacer is characterized in that it consists of spherical, melt-resistant, uniformly sized fine particles obtained by modifying crosslinked polymer fine particles through a polymerization process using a non-crosslinking monomer and a crosslinking monomer. Liquid crystal display element. 2. The device according to claim 1, wherein the uniform particle size fine particles have a particle size of 1 to 10 μm and a standard deviation of particle size distribution of 0.3 μm or less.