JP2702651B2 - Coated fine particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to coated fine particles, and more particularly to a gap material for a liquid crystal display cell, a gap material for an electrochromic display cell, a conductive or insulating spacer for an electrode plate, or a film or sheet for other uses. The present invention relates to fine particles useful as spacers or the like for maintaining gaps between blocks, and coated fine particles for forming fine projections on a flat or concave surface for use in optical measuring instruments and other applications.

[0002]

2. Description of the Related Art Liquid crystal spacers used in liquid crystal display devices, labeling materials such as fluorescent fine particles used in flow cytometry in the field of biochemistry, standard fine particles used when measuring the particle size of particles using an electron microscope, immunology Inorganic or organic fine particles having a uniform particle size have been used as a diagnostic carrier used for a diagnostic reagent. For example, when using these fine particles as a spacer for a liquid crystal display element, these fine particles are arranged at a predetermined gap in a gap between two transparent glass or plastic substrates,
The distance between the two substrates is kept constant. These spacers are described, for example, in JP-A-57-189117,
JP-A-59-24829, JP-A-1-14402
No. 1 discloses this.

However, such a conventional liquid crystal display device has the following problems because the fine particles are not fixed to the substrate.

(1) In a process of assembling a liquid crystal display element, when air is blown on a substrate or air is sucked from the substrate, spacers disposed on the substrate are scattered and disappear.

(2) In the step of injecting liquid crystal into the liquid crystal display element, the spacer moves on the substrate, and the arrangement of the spacer is biased.

(3) When driving the liquid crystal display element, the spacer moves by electric and hydrodynamic forces.

(4) In a color liquid crystal display device equipped with a color filter, the spacer easily falls into the concave portion due to a large step between the portion where the color filter exists and the portion where the color filter does not exist, and as a result, the function as the spacer is achieved. Disappears.

Various attempts have been made to fix the spacer to the substrate in order to solve such disadvantages.
No specific method has been established.

For example, Japanese Patent Application Laid-Open No. 1-247155 discloses a method for producing adhesive fine particles by coating organic or inorganic fine particles with an olefin resin. However, since the olefin-based resin exhibits tackiness even at room temperature, if the adhesive fine particles are left for a long time, they tend to be gradually blocked, and cannot withstand long-term storage.

Further, Japanese Patent Application Laid-Open No. 63-94224 discloses a method in which acrylic resin fine particles are adhered to fine particles by a mechanical method (mechanofusion method) to obtain adhesive fine particles. However, the adhesive fine particles obtained by this method have poor adhesion, and the resin fine particles coated with the fine particles dissolve in the liquid crystal. Therefore, when such adhesive fine particles are used as a spacer in a liquid crystal display device, it is difficult to fix the spacer in a cell into which liquid crystal has been injected.

Further, it has been proposed that the surface of organic or inorganic fine particles is coated with an epoxy resin, and this coating layer is used as an adhesive layer. The use of epoxy resins is intended to obtain adhesive properties when cured by heat. An amine compound is required to cure the epoxy resin, but the amine compound may adversely affect the operation of the liquid crystal, and is not preferably used for a liquid crystal display device. Further, there is a disadvantage that the life of the adhesive layer is short, and it is necessary to store at a low temperature for long-term storage.

As described above, a bondable spacer used for a liquid crystal display element or the like must not only have a role as a spacer, but also have no adverse effect on the liquid crystal, such as abnormal alignment and disclination. .

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide, when used as a spacer for a liquid crystal display cell, desired adhesion to a substrate. An object of the present invention is to provide fine particles which can be fixed to a substrate and have no adverse effect on liquid crystal.

[0014]

The first coated fine particles of the present invention are coated fine particles having a core fine particle made of an organic material or an inorganic material and a coating layer provided on the surface of the core fine particles. The layer is composed of a vinyl polymer having a double bond in a side chain, and the polymer includes a vinyl polymer having a reactive group in a side chain, a group capable of reacting with the reactive group, and a double bond. Characterized by being obtained by reaction with a compound having the above formula, whereby the above object is achieved.

The second coated fine particles of the present invention are coated fine particles having a core fine particle made of an organic material or an inorganic material and a coating layer provided on the surface of the core fine particles. A vinyl polymer having a double bond, and a polymerization initiator, wherein the polymer has a vinyl polymer having a reactive group in a side chain, a group capable of reacting with the reactive group, and a double bond. Characterized by being obtained by reaction with a compound having the above formula, whereby the above object is achieved.

Next, the present invention will be described in detail.

The first coated fine particles of the present invention are coated fine particles having core fine particles and a coating layer provided on the surface of the core fine particles.

The core fine particles are made of an organic or inorganic material. Examples of the organic material include the following resins: polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polytetrafluoroethylene, polystyrene, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyamide,
Thermoplastic resins such as polysulfone, polyphenylene oxide and polyacetal; homopolymers or copolymers of monomers having two or more double bonds in the molecule, for example, divinylbenzene polymer, divinylbenzene-styrene copolymer And divinylbenzene-methacrylic acid ester copolymers, divinylbenzene-acrylonitrile copolymers, triallyl isocyanurate polymers; and thermosetting resins such as epoxy resins, phenol resins and melamine resins. Among the above organic materials, melamine resin, divinylbenzene polymer, divinylbenzene-styrene copolymer,
Divinylbenzene-methacrylic acid ester copolymer, divinylbenzene-acrylonitrile copolymer and triallyl isocyanurate polymer are particularly preferred.

Examples of the inorganic material include silicate glass, borosilicate glass, lead glass, soda-lime glass, alumina, and aluminum silicate. Among the inorganic materials, silicate glass and borosilicate glass are particularly preferred.

The shape of the core fine particles is not limited.
A spherical shape, an elliptical spherical shape, and a cylindrical shape having the following dimensions are preferable. In the case of a true sphere, the diameter is preferably 0.1 to 1
000 μm, particularly preferably 1 μm to 100 μm. In the case of an elliptical sphere, the minor axis is preferably 0.1 to
The length is 1000 μm, particularly preferably 1 μm to 100 μm, and the major axis to the minor axis is preferably 1 to 10, particularly preferably 1 to 5. In the case of a cylindrical shape, the diameter is preferably 0.5 to 1000 μm,
Particularly preferably, it is 3 to 100 μm.

The core fine particles may be colorless or colored by an appropriate method. When the core fine particles are colored, they can be obtained as follows. When the core fine particles are made of an organic material, carbon black,
It is obtained by treating the core fine particles with a disperse dye, an acid dye, a basic dye, a metal oxide or the like. When the core fine particles are made of an inorganic material, a coating layer made of an organic material is first formed on the surface of the core fine particles, and then the coating layer is decomposed or carbonized at a high temperature. Alternatively, it can be obtained by adding a coloring component to the inorganic material forming the core fine particles.

The coating layer of the coated fine particles of the present invention contains a vinyl polymer having a double bond in a side chain; or the polymer and a polymerization initiator.

The vinyl polymer having a double bond in the side chain is composed of a vinyl polymer having a reactive group in the side chain and a compound having a group capable of reacting with the reactive group and a double bond. Obtained by reaction.

The vinyl polymer having a reactive group in the side chain is usually obtained by reacting a vinyl monomer having a reactive group with a vinyl monomer having no reactive group.
Here, the reactive group refers to a reactive group other than a vinyl group, for example, a hydroxyl group, a carboxyl group, an acid anhydride group, a glycidyl group and the like. The vinyl monomer having a reactive group is represented, for example, by the following general formula (I) or (II).

[0025]

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(Wherein, R ¹ represents a hydrogen atom or a methyl group, and X represents a hydroxylethyl group, a hydroxylpropyl group or a glycidyl group).

[0027]

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(Wherein, R ^{2 and} R ³ each independently represent a hydrogen atom or a methyl group).

Examples of the vinyl monomer having no reactive group include a monomer represented by the following general formula (III). Specifically, styrene, acrylonitrile, methyl methacrylate, isobutyl methacrylate , Ethyl methacrylate, benzyl methacrylate, and vinyl acetate.

[0030]

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(Wherein, R ⁴ and R ⁵ each independently represent a hydrogen atom, a linear alkyl group, a branched alkyl group, a phenyl group, a halogen atom, a carboxylic acid ester group or a nitrile group).

The compounds having a group capable of reacting with the reactive group of the vinyl monomer and a double bond include the following compounds.

1) When the vinyl monomer having a reactive group is a vinyl monomer having a hydroxyl group, acid chloride having a double bond, isocyanate having a double bond, silane having a double bond Compounds and acid anhydrides having a double bond are exemplified.

2) When the vinyl monomer having a reactive group is a vinyl monomer having a glycidyl group, a carboxylic acid having a double bond, an isocyanate having a double bond, and a double monomer having a double bond. Examples include silane compounds.

3) When the vinyl monomer having a reactive group is a vinyl monomer having an acid anhydride group, examples thereof include alcohols having a double bond.

If the content of the group capable of reacting with a reactive group and the compound having a double bond in the vinyl polymer having a double bond in the side chain is too small, the content of the compound for a liquid crystal display element spacer or the like is too small. When used, they may swell in the liquid crystal or dissolve in the liquid crystal. On the other hand, if the content of the compound is too large, it becomes difficult to synthesize a polymer having a double bond in a side chain forming the coating layer, and the adhesiveness of the coating layer may be deteriorated.

Accordingly, the compound having a group capable of reacting with the reactive group and the double bond is occupied by the double bond in the resulting polymer having the double bond in the side chain represented by the following formula. It is preferable that the content is contained such that the ratio K is 0.027 to 8.1.

[0038]

(Equation 1)

The thickness of the coating layer of the coated fine particles of the present invention is preferably 2 to 10% of the diameter of the core fine particles. When the thickness of the coating layer is less than 2% of the diameter of the core fine particles, the adhesion between the core fine particles and the coating layer is insufficient. On the other hand, when the thickness of the coating layer exceeds 10% of the diameter of the core fine particles, it is obtained. When the coated fine particles are used as a spacer for a liquid crystal display element, in the step of heating the coated fine particles to adhere to the substrate, the coating layer melts and spreads to a portion that does not need to exhibit an adhesive force. Adversely affect the operation of the liquid crystal,
As a result, image display may be degraded.

The above-mentioned coating layer contains a polymerization initiator as required. This polymerization initiator has a half-life of 100
It is preferable that the temperature, which is the time, is 80 ° C. or higher. If the temperature at which the half-life is 100 hours is less than 80 ° C., the decomposition of the polymerization initiator proceeds remarkably in the step of forming the coating layer, so that the adhesion in the adhesion step may not be easy. Furthermore, the change in performance during storage becomes remarkable, and the quality of the coated fine particles obtained may deteriorate. Examples of the polymerization initiator include peroxyketal (PK), dialkyl peroxide (DAP), peroxydicarbonate (PDC), peroxyester (POE), and the like. Compounds.

[0041]

[Table 1]

To obtain the coated fine particles of the present invention, for example,
First, a vinyl monomer having a reactive group and a vinyl monomer having no reactive group are polymerized while coexisting with the core fine particles to obtain a polymer having a reactive group in a side chain. As a method of polymerizing the above monomers, solution polymerization,
There are methods such as bulk polymerization and emulsion polymerization. Considering the introduction of a double bond into the polymer in a later step, the above polymerization method is more preferably a solution polymerization.

Next, a polymer having a double bond in the side chain is obtained by reacting a reactive group on the side chain of the polymer with a group having a double bond and a group capable of reacting with the reactive group. .
First, a compound having a group capable of reacting with the reactive group and a compound having a double bond is added to the core fine particles coated with the polymer having a reactive group on the side chain, and the polymer is reacted with the compound. . As a result, a polymer having a double bond in the side chain is formed, and core fine particles coated with the polymer are obtained.

In the case of obtaining coated fine particles containing a polymerization initiator in the coating layer, usually, the above-mentioned reaction solution having been reacted with the group capable of reacting with the reactive group and the compound having a double bond is added to the reaction solution. Add the polymerization initiator. By drying and pulverizing the coated fine particles thus obtained, coated fine particles having a desired particle size can be obtained.

Further, when the coated fine particles of the present invention are used as a spacer for a liquid crystal display device or the like, the coated fine particles are sprayed on a substrate, and the coating layer is melted by heat treatment. And then inject liquid crystal. The heat treatment is preferably performed at a temperature in the range of 150 to 200 ° C., whereby the double bond of the polymer having a double bond in the side chain is polymerized to form a crosslinked structure, and the coating layer is formed. To cure. When a polymerization initiator is contained, this reaction is accelerated. The cured coating layer has good adhesiveness to the substrate, and the components constituting the coating layer do not dissolve in the liquid crystal.

[0046]

In the coated fine particles of the present invention, the coating layer, which is an adhesive resin provided on the surface, does not show any adhesiveness at a normal working temperature (40 ° C. or lower). However, when heat treatment is performed on the coated fine particles disposed on the substrate, the coating layer is in a fluid state, and a contact area enough to adhere to the substrate is secured. When further heated, the polymer having a double bond in the side chain contained in the coating layer polymerizes to form a crosslinked structure, and as a result, the coating layer is cured. Therefore, when the coated fine particles of the present invention are used as a spacer for a liquid crystal display device, they have sufficient adhesiveness to a substrate and do not elute into the liquid crystal.

[0047]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 100 g of divinylbenzene copolymer fine particles (core fine particles) having a particle size of 8.00 μm were placed in a flask, 300 g of methyl ethyl ketone was added, and the mixture was sufficiently stirred. The inside of the flask was replaced with nitrogen and heated to 80 ° C. Then, methyl methacrylate 25g, isobutyl acrylate 1
A mixture of monomers consisting of 7 g, 8 g of hydroxyl acrylate and 1.5 g of azobisisobutyronitrile was added dropwise to the flask over 1 hour. After the completion of the dropwise addition, the mixture was heated for 2 hours to complete the polymerization of the monomer, thereby obtaining a solution containing the core fine particles coated with the polymer.

Separately, 1 mol (174 g) of tolylene diisocyanate and 1 mol (116 g) of hydroxyethyl acrylate were reacted to prepare an unreacted urethane acrylate having an isocyanate group.

To the solution containing the coated core fine particles was added 0.2 g of hydroquinone monomethyl ether as a polymerization inhibitor, and then the urethane acrylate 2 was added.
0 g was added, and the mixture was reacted at 80 ° C. for 4 hours. After the reaction was completed, 0.16 g of dicumyl peroxide was added to the mixture,
The mixture was poured on a polyethylene film, dried into a thin plate, and dried. This was roughly pulverized and then further pulverized in a ball mill, and a lump and fine particles having a particle diameter smaller than a predetermined particle size were removed using a sieve to obtain desired coated fine particles.

Adhesion test: The obtained coated fine particles were sprayed on a glass substrate using a spacer sprayer. This is 10
It was measured with a magnifying glass of 0 times magnification. The number of the coated fine particles sprayed was 145 / mm ² .

Next, this was placed in a heating device and heated at 180 ° C. for 1 hour to be fixed on a glass substrate. This was immersed in acetone for 5 minutes, washed with water and dried. When this was measured with a magnifying glass having a magnification of 100 times, the number of coated fine particles on the glass substrate was 144 / mm ² . As a result, it can be seen that the fine particles dispersed on the substrate adhere to and remain on the substrate without substantially reducing the number due to the heat treatment.

In place of the acetone immersion described above, a glass substrate which was similarly heated by applying a spacer thereto was immersed in liquid crystal and left to stand for one hour. As a result of measurement with the same magnifying glass as described above, the number of coated fine particles remaining on the substrate was 14
0 / mm ² . This shows that the adhered coated fine particles almost remain.

A liquid crystal cell was prepared using the coated fine particles, and as a result of evaluation, there was no abnormality except that the liquid crystal having a particle size of about 5% was abnormal in the periphery of the coated fine particles. was gotten.

Comparative Example 1 Coated fine particles were obtained in the same manner as in Example 1 except that a urethane acrylate having no reactive group was used instead of an unreacted urethane acrylate having an isocyanate group.

Adhesion test: The obtained coated fine particles were sprayed on a glass substrate using a spacer sprayer. This is 10
It was measured with a magnifying glass of 0 times magnification. The number of the coated fine particles sprayed was 127 / mm ² .

Next, this was put into a heating device and heated at 180 ° C. for 1 hour. This was immersed in acetone for 5 minutes, washed with water and dried. When this was measured with a magnifying glass of 100 times magnification, the number of coated fine particles on the glass substrate was 1
8 / mm ² . Thus, it can be seen that the fine particles sprayed on the substrate are dissolved in acetone because the crosslinking reaction does not proceed even after the heat treatment, and as a result, the fine particles are not left on the substrate.

Instead of the above-mentioned acetone immersion, a glass substrate which was similarly heated by applying a spacer thereto was immersed in a liquid crystal and allowed to stand for one hour. As a result of measurement with the same magnifying glass as described above, the number of coated fine particles remaining on the substrate was 48
/ Mm ² . This shows that the adhered coated fine particles hardly remain.

Example 2 100 g of divinylbenzene copolymer fine particles having a particle size of 8.00 μm were placed in a flask, and methyl ethyl ketone 300
g was added and stirred well. The inside of the flask was replaced with nitrogen and heated to 80 ° C. Subsequently, 25 g of methyl methacrylate, 20 g of isobutyl acrylate, 5 g of maleic anhydride, and 1.5 g of azobisisobutyronitrile
g of the monomer mixture was dropped into the flask over 1 hour. After the completion of the dropwise addition, the mixture was heated for 2 hours to complete the polymerization of the monomer, thereby obtaining a solution containing the core fine particles coated with the polymer. To this solution was added 0.2 g of hydroquinone monomethyl ether as a polymerization inhibitor, and 6.6 g of hydroxyethyl methacrylate was added.
The reaction was performed at 4 ° C. for 4 hours. After the reaction was completed, 0.2 g of dicumyl peroxide was added to the mixture, and the mixture was poured on a polyethylene film and dried in a thin plate shape. This was roughly pulverized and then further pulverized in a ball mill, and a lump and fine particles having a particle diameter smaller than a predetermined particle size were removed using a sieve to obtain desired coated fine particles.

Adhesion test: The obtained coated fine particles were sprayed on a glass substrate using a spacer sprayer. This is 10
It was measured with a magnifying glass of 0 times magnification. The number of the coated fine particles sprayed was 115 / mm ² .

Next, this was placed in a heating device, heated at 180 ° C. for 1 hour, and fixed on a glass substrate. This was immersed in acetone for 5 minutes, washed with water and dried. When this was measured with a magnifying glass having a magnification of 100 times, the number of coated fine particles on the glass substrate was 110 / mm ² . As a result, it can be seen that the fine particles dispersed on the substrate adhere to and remain on the substrate without substantially reducing the number due to the heat treatment.

In place of the acetone immersion described above, a glass substrate on which spacers were sprayed and heat-treated was immersed in liquid crystal and left for 1 hour. As a result of measurement with the same magnifying glass as described above, the number of coated fine particles remaining on the substrate was 10
2 / mm ² . This shows that the adhered coated fine particles almost remain.

Comparative Example 2 Coated fine particles were obtained in the same manner as in Example 2 except that 5 g of isobutyl methacrylate was used instead of 5 g of maleic anhydride.

Adhesion test: The coated fine particles obtained were sprayed on a glass substrate using a spacer sprayer. This is 10
It was measured with a magnifying glass of 0 times magnification. The number of the coated fine particles sprayed was 125 / mm ² .

Next, this was put into a heating device and heated at 180 ° C. for 1 hour. This was immersed in acetone for 5 minutes, washed with water and dried. When this was measured with a magnifying glass of 100 times magnification, the number of coated fine particles on the glass substrate was 5
8 / mm ² . As a result, it can be seen that the fine particles sprayed on the substrate dissolve in acetone because the crosslinking reaction does not proceed even after the heat treatment, and as a result, the fine particles are not left on the substrate.

In place of the acetone immersion described above, a glass substrate on which spacers were sprayed and heat-treated was immersed in liquid crystal and left for 1 hour. As a result of measurement with the same magnifying glass as described above, the number of coated fine particles remaining on the substrate was 28
/ Mm ² . This shows that the adhered coated fine particles hardly remain.

Example 3 100 g of divinylbenzene copolymer fine particles having a particle size of 7.50 μm were placed in a flask, and methyl ethyl ketone 300
g was added and stirred well. The inside of the flask was replaced with nitrogen and heated to 80 ° C. Subsequently, a mixture of monomers composed of 25 g of methyl methacrylate, 17 g of isobutyl acrylate, 8 g of hydroxyethyl acrylate, and 1.4 g of azobisisovaleronitrile was dropped into the flask over 1 hour. After the completion of the dropwise addition, the mixture was heated for 2 hours to complete the polymerization of the monomer, thereby obtaining a solution containing the core fine particles coated with the polymer.

Separately, 1 mol (174 g) of tolylene diisocyanate and 1 mol (130 g) of hydroxyethyl methacrylate were reacted to prepare an unreacted urethane acrylate having an isocyanate group.

To the solution containing the coated core fine particles was added 0.2 g of hydroquinone monomethyl ether as a polymerization inhibitor, and then the urethane acrylate 2 was added.
1 g was added and reacted at 80 ° C. for 9 hours. After the completion of the reaction, the mixture was flowed on a polyethylene film, dried in a thin plate shape. This was roughly pulverized and then further pulverized in a ball mill, and a lump and fine particles having a particle diameter smaller than a predetermined particle size were removed using a sieve to obtain desired coated fine particles.

Adhesion test: The obtained coated fine particles were sprayed on a glass substrate using a spacer sprayer. This is 10
It was measured with a magnifying glass of 0 times magnification. The number of the coated fine particles sprayed was 140 / mm ² .

Next, this was placed in a heating device and heated at 180 ° C. for 1 hour to be fixed on a glass substrate. This was immersed in acetone for 5 minutes, washed with water and dried. When this was measured with a magnifying glass having a magnification of 100 times, the number of coated fine particles on the glass substrate was 134 / mm ² . As a result, it can be seen that the fine particles dispersed on the substrate adhere to and remain on the substrate without substantially reducing the number due to the heat treatment.

In place of the above acetone immersion, a glass substrate on which spacers were sprayed and heat-treated was immersed in liquid crystal and left for 1 hour. As a result of measurement with the same magnifying glass as described above, the number of coated fine particles remaining on the substrate was 12
8 / mm ² . This shows that the adhered coated fine particles almost remain.

A liquid crystal cell was prepared using the coated fine particles, and as a result of evaluation, there was no abnormality except for a liquid crystal having a particle size of about 3% in the periphery of the coated fine particles. was gotten.

[0074]

When the coated fine particles of the present invention are used as a spacer for a liquid crystal display device, the coated fine particles of the present invention show no adhesiveness at a normal working temperature (40 ° C. or lower). However, when heat treatment is performed on the coated fine particles disposed on the substrate, the particles have sufficient adhesiveness to the substrate and do not elute into the liquid crystal. Therefore, the operation as a display element is not affected and an excellent effect as a spacer is exhibited.

The fine particles of the present invention can be used as a gap material for a liquid crystal display cell, a gap material for an electrochromic display cell, a spacer for an electrode plate, or a spacer for maintaining a gap between films, sheets and blocks for other uses. It is useful, and may also be used to form microprojections on a flat or concave surface for optical or other uses, and the like.

Claims (2)

(57) [Claims] 1. A coated fine particle having a core fine particle made of an organic material or an inorganic material and a coating layer provided on the surface of the core fine particle, wherein the coating layer has a double bond having a double bond in a side chain. The polymer is obtained by reacting a vinyl polymer having a reactive group in a side chain with a compound having a group capable of reacting with the reactive group and a double bond. Coated fine particles, 2. A coated fine particle comprising a core fine particle made of an organic material or an inorganic material and a coating layer provided on the surface of the core fine particle, wherein the coating layer has a double bond having a double bond in a side chain. Coalescing,
And a polymerization initiator, wherein the polymer is obtained by a reaction between a vinyl polymer having a reactive group in a side chain and a compound having a group capable of reacting with the reactive group and a double bond. Coated microparticles, characterized in that: