JP3187592B2 - Spacer for liquid crystal display panel and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel spacer for liquid crystal display panels comprising organic-siloxane composite spherical fine particles having a very uniform particle diameter and a method for producing the same.

[0002]

2. Description of the Related Art A liquid crystal display panel has a structure in which a spacer is interposed between two opposing electrode substrates, and a liquid crystal material is sandwiched between the spacers. The spacer is used to keep the thickness of the liquid crystal layer uniform and constant, and is used as an in-plane spacer in the liquid crystal layer and a seal spacer in the peripheral adhesive sealing material.

In general, since the spacer for a liquid crystal display panel is very expensive, it is desirable that the amount of the spacer used is as small as possible. In particular, when using in-plane spacers that are in direct contact with the liquid crystal material, the use of such spacers in order to minimize the elution of ions and molecules into the liquid crystal from inside the spacers that adversely affects the display performance of the liquid crystal display panel. The amount used should be as low as possible.

The display performance required for practical use of a liquid crystal display panel generally includes high-speed response, high contrast, wide viewing angle, and the like. In order to realize these various performances, the thickness of the liquid crystal layer, that is, the gap distance between the two electrode substrates must be kept strictly constant. As a spacer for a liquid crystal display panel meeting such a demand,
Silica fine particles produced by a sol-gel method (JP-A-62-2
No. 69933), calcined silica fine particles (Japanese Patent Laid-Open No. 1-234826), polymer fine particles obtained by suspension polymerization of a styrene monomer and the like, and the like.
Both are spherical fine particles having a very uniform particle size distribution.

Conventionally, in applying silica fine particles produced by a sol-gel method to a spacer for a liquid crystal display panel, in order to improve the dispersibility of the fine particles on an electrode substrate, or to improve the liquid crystal on the surface of the fine particles. In order to suppress the occurrence of misalignment of the substance, there has been devised surface treatment of the fine particles with an alcohol, a coupling agent, etc.
269933).

[0006]

However, the prior art has the following problems, and it has not been possible to obtain a spacer for a liquid crystal display panel capable of controlling the hardness and mechanical resilience of fine particles. (1) The calcined silica fine particles have poor deformability, and the particle size distribution directly affects the nonuniformity of the gap distance, and image unevenness is likely to occur. Further, since these fine particles are very hard as a material, there is a problem that physical damage is caused to a vapor deposited layer such as an electrode on a substrate, an alignment film, and a coat layer such as a color filter. Further, when a liquid crystal display panel using these fine particles is exposed to a low temperature environment of, for example, −40 ° C., there is a large difference in the thermal expansion coefficient between the liquid crystal and the fine particles. This causes a problem of so-called low-temperature foaming in which the display function does not operate at all.

(2) Although unfired silica fine particles have improved hardness as compared with fired products, they have poor mechanical resilience.
As in the case of the silica fired product fine particles, image unevenness is likely to occur and there is a problem of low-temperature foaming. (3) Since styrene-based polymer fine particles are very soft as a material, it is very difficult to finely adjust the electrode substrate gap distance. For example, usually, the gap distance is adjusted by bonding an adhesive seal to fix both electrode substrates in a state where a peripheral seal material in which a seal spacer is dispersed and an in-plane spacer are sandwiched between two opposing electrode substrates. This is performed in the step of hot pressing both substrates at the curing temperature of the material. However, since the styrene-based polymer fine particles are very soft, it is extremely difficult to achieve a uniform gap distance only by the above-described process alone.After returning both substrates to room temperature again, the gap distance is reduced by cold pressing. An extra step of fine adjustment is required.

Further, since the organic fine particles are very soft, in order to keep the gap distance uniform and constant, it is necessary to increase the number of fine particles to be scattered. As a result, not only does the production cost rise, but also the area of the part where no image is formed increases, and furthermore, the amount of impurities such as ions and molecules dissolving out of the spacer into the liquid crystal layer also increases. , Display quality, such as a decrease in contrast and an increase in roughness.

Therefore, the present invention provides a liquid crystal display panel having a hardness between a silica fine particle and a polymer fine particle, and also having a mechanical restoring property necessary for maintaining a uniform gap distance uniformly. It is an object to provide a spacer for use and a method for manufacturing the same.

[0010]

In order to solve the above-mentioned problems, a spacer for a liquid crystal display panel according to the present invention comprises an organic-siloxane composite in which an organic compound capable of chemically bonding to a silanol group is bonded to the inside and the surface of fine particles. Spherical fine particles, wherein the composition ratio of the organic compound to the siloxane in the fine particles is such that the amount of the organic compound is represented by the total number of moles of carbon and the siloxane is represented by the number of moles of Si.
It is characterized by a range of 0:50.

The organic compound capable of forming a chemical bond with a silanol group as referred to in the present invention means the formation of a chemical bond with the silanol group represented by the following chemical formula 2, which is present in the minimum structural unit of the siloxane represented by the following chemical formula 1. There is no particular limitation as long as it is an organic compound having a functional group capable of

[0012]

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[0013]

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As the organic compound, specifically, an organic compound having an alcoholic hydroxyl group, an epoxy group, an amino group, a carboxyl group, an isocyanate group, or the like, generally has a functional group highly reactive with a silanol group. Organic compounds may be mentioned. Preferably, monohydric alcohols,
Dihydric or higher polyhydric alcohols, more preferably, the above alcohols having 1 to 10 carbon atoms are used. Among them, a polyhydric alcohol represented by the following general formula 3 is particularly preferable.

[0015]

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Wherein R is a methyl group or hydrogen, and n is 1
Represents an integer of 10 to 10. ) These organic compounds may be used alone or as a mixture of two or more. The composition ratio of the organic compound and the siloxane in the composite spherical fine particles of the present invention is represented by the following formula: the amount of the organic compound is represented by the total number of moles of carbon, and the siloxane is represented by the number of moles of Si.
It must be in the range of 0:50. If the amount of the organic compound is less than this ratio, sufficient mechanical resilience cannot be obtained, and the particles become harder than necessary. When the amount of the organic compound is larger than this ratio, the particles are unnecessarily soft.

The surface state of the composite spherical fine particles is preferably as smooth as possible. In particular, in the case of porous particles, it is not preferable because ions, molecules, and the like, which adversely affect the display performance of the liquid crystal display panel, such as adsorbed moisture, are easily adsorbed inside the pores. Further, in order to improve the dispersibility of the composite spherical fine particles on the electrode substrate, or to suppress poor alignment of the liquid crystal substance on the surface of the composite spherical fine particles, or for other purposes, a coupling agent or the like is used. A conventionally known surface modification treatment may be applied to use as a spacer.

Further, the method for producing a spacer for a liquid crystal display panel according to the present invention is characterized in that the spherical silica hydrate fine particles obtained by hydrolyzing and condensing a hydrolyzable silicon compound in an organic solvent containing water are treated with silanol. Heating is performed in the presence of an organic compound capable of chemically bonding to a group. The method for obtaining the composite spherical fine particles of the present invention is not particularly limited, and the composition ratio of the organic compound and the siloxane in the composite spherical fine particles is such that the amount of the organic compound is the total number of moles of carbon, and the siloxane is the amount of Si. It may be produced by any method such that C: Si = 10: 90 to 50:50 in terms of moles.

As a specific production method, for example, a hydrolyzable silicon compound is hydrolyzed and condensed in an organic solvent containing water to first synthesize a spherical silica hydrate fine particle slurry, and then to form a slurry. After subjecting the fine particles to a heat treatment in the presence of the above-mentioned organic compound capable of chemically bonding to a silanol group, a method of isolating the fine particles can be mentioned. In the synthesis of the spherical silica hydrate fine particles, seed particles may be charged in the synthesis system. By selecting the conditions of the heat treatment (temperature, time, etc.), the composition ratio of the organic compound to the siloxane can be arbitrarily set within the above range.

The hardness and mechanical resilience of the fine particles used for the spacer can be measured by the following measuring methods. Shimadzu Micro Compression Testing Machine (M made by Shimadzu Corporation)
According to CTM-200), at room temperature, a load is gradually applied to a sample particle at a constant load speed in the direction of the center of the particle using a circular flat indenter having a diameter of 50 μm, and the compression displacement becomes 20% of the particle diameter. Deform the particles until. Immediately thereafter, the load is gradually unloaded at the same speed as when the load is applied, and the load is finally removed until the load becomes zero. This operation is performed on three different particles of the same material, and the hardness of the particles is defined as a value obtained by standardizing the average value of the magnitude of the load at the time of 20% deformation by a unit diameter according to the following equation. Then, when the load is set to 0 after unloading, the average value of the percentage of the size of the deformation (hereinafter referred to as “residual displacement”) still remaining in the particles with respect to the particle diameter is represented by the mechanical resilience of the particles. Scale.

H = F / R²  H: hardness of sample particles (kg / mm²) F: Compressive load (kg) R: Particle diameter (mm) When the hardness of conventional spacer fine particles is represented by the above value,
When firing silicaobject130kg / mm fine particles², Stille
Polymer fine particles9.2kg / mm²Was
According to the present invention, 20 to 70 kg / mm²In the range of
The composite spherical fine particles whose hardness is adjusted are obtained. one
On the other hand, when the mechanical resilience is represented by the above value,
The silica fine particles had a residual displacement of 13%.
Has an arbitrary residual displacement in the range of 0 to 10%.
Fine particles are obtained.

The degree of hardness and mechanical resilience can be achieved by adjusting the composition ratio of the organic compound and siloxane. The average particle size of the composite spherical fine particles of the present invention can be arbitrarily produced depending on the size of the target gap distance, and is usually preferably 0.5 to 20 μm,
More preferably, it is 10 μm.

The uniformity of the particle diameter is preferably 20% or less, more preferably 10% or less, from the viewpoint of the uniformity of the gap distance. The variation coefficient of the particle diameter is defined by the following equation. Coefficient of variation of particle diameter (%) = (σ / X) × 100 σ: Standard deviation of particle diameter X: Average particle diameter In the present invention, a method for producing a liquid crystal display panel using composite spherical fine particles as a spacer includes: After dispersing the composite spherical fine particles uniformly on one of the two electrode substrates by a wet method or a dry method, the composite spherical fine particles are dispersed in an adhesive sealing material such as an epoxy resin, and then the other. Put the thing applied by means such as screen printing on the adhesive seal part of the electrode substrate, apply moderate pressure, and heat at a temperature of 100 to 150 ° C. for 30 to 60 minutes,
After the adhesive sealing material is cured by heating, a method of injecting liquid crystal to obtain a liquid crystal display panel can be cited, but the present invention is not limited by the method of manufacturing the liquid crystal display panel.

[0024]

The chemical structure of the composite spherical fine particles of the present invention is microscopically composed of molecules of an organic compound capable of chemically bonding to a silanol group and SiO ₄ tetrahedron which is a structural unit of siloxane. Are amorphous solids having a structure in which they are chemically bonded to each other with random bonding angles. In the composite spherical fine particles, the organic compound bonded to the fine particles is distributed in the inside and the surface of the fine particles with a uniform or certain continuous distribution in the radial direction of the fine particles. It is clearly distinguished from those in which the radial distribution of the particles of the core material or the shell material is discontinuous. in this way,
The composite spherical fine particles of the present invention have good mechanical resilience because the organic and inorganic substances are distributed inside and on the fine particles with uniform or certain continuous distribution in the radial direction of the fine particles.

In addition, the composite spherical fine particles of the present invention have an appropriate hardness because of the mixture of organic matter and inorganic matter.
When used as a spacer for a liquid crystal display panel, the gap distance between two electrode substrates can be kept constant, and the electrode substrate surface is not damaged. Furthermore, since the composite spherical fine particles of the present invention are obtained by reacting an organic compound in a suspension of spherical silica hydrate fine particles, the particle diameters are very uniform.

[0026]

Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. Example 1 In a 2 liter glass reactor equipped with a stirrer, a dropping port and a thermometer, 470 parts by weight of methanol, 360 parts by weight of 25% aqueous ammonia, and an average particle diameter of 1.2 μm as seed particles were used.
Was added and uniformly mixed. A solution in which 507 parts by weight of ethyl silicate was dissolved in 256 parts by weight of methanol was dropped from the dropping port over 5 hours while the mixture was adjusted to 35 ± 0.5 ° C. and uniformly stirred. After the dropwise addition, the mixture was stirred uniformly for 1 hour to carry out hydrolysis and condensation to obtain a suspension (A) of spherical silica hydrate fine particles.

2 l equipped with stirrer, dropper and thermometer
A glass reactor was prepared separately and methanol 47
4 parts by weight, 340 parts by weight of 25% aqueous ammonia and 136 parts by weight of the suspension (A) as a seed particle slurry were dropped and uniformly mixed. While adjusting the mixture to 35 ± 0.5 ° C. and stirring uniformly, a solution prepared by dissolving 320 parts by weight of ethyl silicate in 186 parts by weight of methanol was added through the dropping port.
It was dropped over time. After the dropwise addition, stirring was continued uniformly for 1 hour to carry out hydrolysis and condensation to obtain a suspension (B) of spherical silica hydrate fine particles.

Ethylene glycol 320 in suspension (B)
Parts by weight, and concentrated at normal pressure using an evaporator. When the internal temperature reached 150 ° C., heating was continued for 1 hour, and ethylene glycol-siloxane composite spherical fine particles in which ethylene glycol was bonded to the particle surface and inside were added. A slurry of ethylene glycol was obtained. After this ethylene glycol slurry was subjected to solid-liquid separation by filtration, washing with methanol was repeated three times, and the obtained solid was dried in a vacuum dryer at 100 ° C. for 3 hours to obtain an average particle size of 5.
A powder of spherical particles of the ethylene glycol-siloxane composite having a particle size of 94 μm and a variation coefficient of 1.9% without agglomeration or polarization of the particle size distribution was obtained.

When the hardness and mechanical resilience of the obtained composite spherical fine particles were evaluated by the aforementioned method, the hardness was 64.
kg / mm ² , and the residual displacement was 7.5%. The composition ratio of the organic compound and the siloxane in the composite spherical fine particles by elemental analysis was C: Si = 31: 69, where the amount of the organic compound was represented by the total number of moles of carbon and the siloxane by the number of moles of Si. Was.

When the above-mentioned composite spherical fine particles were sandwiched between the electrode substrates for a liquid crystal display panel, the periphery thereof was sealed, and the inside was filled with liquid crystal, the liquid crystal operated without the above-mentioned problems. -Example 2 In the same manner as in Example 1 except that heating at 260 ° C with triethylene glycol was used instead of heating at 150 ° C with ethylene glycol, the average particle diameter was 6.06 µm, and the variation coefficient was 1.9%. Thus, a triethylene glycol-siloxane composite spherical fine particle powder having no particle aggregation or polarization in particle size distribution was obtained.

When the hardness and mechanical resilience of the obtained composite spherical fine particles were evaluated by the aforementioned method, the hardness was 48.
kg / mm ² , and the residual displacement was 9.5%. The composition ratio of the organic compound and the siloxane in the composite spherical fine particles by elemental analysis was C: Si = 15: 85, where the amount of the organic compound was expressed by the total number of moles of carbon and the siloxane by the number of moles of Si. Was.

The above-mentioned composite spherical fine particles were sandwiched between the electrode substrates for a liquid crystal display panel, the periphery thereof was sealed, and then liquid crystal was filled therein. As a result, the liquid crystal operated without the above-mentioned problems. -Comparative Example 1-An average particle size of 5.67 µm was obtained in the same manner as in Example 1 except that heating at 150 ° C for 1 hour with ethylene glycol was replaced with heating at 120 ° C for 15 minutes with ethylene glycol. A powder of ethylene glycol-siloxane composite spherical fine particles having a coefficient of variation of 1.9% and free from aggregation of particles and polarization of particle size distribution was obtained.

When the hardness and mechanical resilience of the obtained composite spherical fine particles were evaluated by the aforementioned method, the hardness was 56
kg / mm ² , and the residual displacement was 13%. The composition ratio of the organic compound and the siloxane in the composite spherical fine particles by elemental analysis was as follows: the amount of the organic compound was represented by the total number of moles of carbon, and the siloxane was represented by the number of moles of Si. Was.

When the above-mentioned composite spherical fine particles are sandwiched between the electrode substrates for a liquid crystal display panel, the periphery thereof is sealed, and the inside is filled with liquid crystal, the above-mentioned problem occurs, and the liquid crystal display panel cannot be used as a spacer. There was nothing. Comparative Example 2 After the suspension (B) in Example 1 was subjected to solid-liquid separation by filtration, washing with methanol was repeated three times, and the obtained solid was dried in a vacuum dryer at 100 ° C. for 3 hours. Thus, spherical silica fine particles having an average particle diameter of 5.67 μm and a variation coefficient of 1.9% and having no aggregation of the particles or polarization of the particle diameter distribution were obtained. The whole amount of the obtained fine particle powder was dispersed in 320 parts by weight of ethylene glycol using a throw-in type ultrasonic oscillator, and then concentrated at normal pressure using an evaporator, and heated at an internal temperature of 150 ° C. for 1 hour. Was continued to obtain an ethylene glycol slurry of spherical silica fine particles.

After the ethylene glycol slurry was separated into solid and liquid by filtration, washing with methanol was repeated three times, and the obtained solid was dried in a vacuum dryer at 100 ° C. for 3 hours to give an average particle size of 5.67 μm. , Variation coefficient 1.9
%, A powder of spherical silica fine particles free from particle aggregation and polarization of the particle size distribution was obtained. When the hardness and mechanical resilience of the obtained spherical silica fine particles were evaluated by the above-described method,
The hardness was 64 kg / mm ² and the residual displacement was 12%. Further, the composition ratio of the organic compound and the siloxane in the composite spherical fine particles by elemental analysis is represented by the following formula: the amount of the organic compound is expressed by the total number of moles of carbon, and the siloxane is expressed by the number of moles of Si.
0.04: 99.96.

When the above-mentioned composite spherical fine particles are sandwiched between the electrode substrates for a liquid crystal display panel, the periphery thereof is sealed, and then the inside is filled with liquid crystal, the above-described problem occurs, and the liquid crystal display panel can be used as a spacer. There was nothing.

[0037]

As described above, the organic-siloxane composite spherical fine particles serving as the spacer for the liquid crystal display panel of the present invention have a very uniform particle diameter, and have a high hardness between the silica fine particles and the polymer fine particles. It has resilience. Therefore, by using the fine particles of the present invention as a spacer for a liquid crystal display panel, the surface of the electrode substrate is not damaged, low-temperature bubbling occurs, image unevenness occurs, manufacturing costs increase, and various display performances do not decrease. Thus, a high-performance liquid crystal display panel having excellent image quality can be manufactured.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideki Oishi 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo Japan 1 Nippon Shokubai Himeji Works Co., Ltd. Hei 1-234826 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1339 500

Claims (2)

(57) [Claims] 1. An organic-siloxane composite spherical fine particle in which an organic compound capable of chemically bonding to a silanol group is bonded to the inside and the surface of the fine particle, wherein the composition ratio of the organic compound and the siloxane in the fine particle is The amount is represented by the total number of moles of carbon, and the siloxane is expressed by the number of moles of Si.
A spacer for a liquid crystal display panel, wherein i = 10: 90 to 50:50. 2. A spherical silica hydrate fine particle obtained by hydrolyzing and condensing a hydrolyzable silicon compound in an organic solvent containing water is heated in the presence of an organic compound capable of chemically bonding to a silanol group. A method for manufacturing a spacer for a liquid crystal display panel according to claim 1.