JP2544029B2 - Colored fine particles, method for producing the same, and liquid crystal display device using 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 colored fine particle which is colored to the inside of the fine particle and is excellent in heat resistance and chemical resistance, a method for producing the same, and a liquid crystal display device produced by using the colored fine particle and having a good contrast ratio.

[0002]

2. Description of the Related Art Colored fine particles are used in various fields such as colorants such as plastics and toners. In particular, colored fine particles having a uniform particle size are effective for liquid crystal display devices, standard particles, and the like. As a spacer for a liquid crystal display device, a crushed glass fiber has been conventionally used (Japanese Patent Laid-Open No. 57-54923).
No.), a crosslinked body of silica and a thermoplastic resin (JP-A-57 / 57).
-70520) and other spherical fine particles are used. Since the liquid crystal display element is basically a light receiving type display element,
It has the drawback of being difficult to see in the dark. Therefore, a so-called backlit liquid crystal display element has been developed which illuminates the screen from the back surface of the liquid crystal display element to brighten the screen and withstand use even in a dark place. However, since the spacer is transparent, there is a problem that the light of the backlight on the back surface of the liquid crystal display element leaks through the spacer and the contrast is lowered.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In order to solve this problem, various attempts have been disclosed in which the surface of the above-mentioned transparent spacer is coated with a dye or a metal oxide to provide a light-shielding property. There is. For example, Japanese Patent Laid-Open Nos. 1-144021 and 2
No. 24629, such as colored spherical fine particles of a cross-linked polymer. However, when the surface portion is coated with a dye and a metal oxide, there are problems such as elution and drop-off with respect to liquid crystal, and a step of coating with a transparent resin or modifying with a surface treatment agent is required. However, there has been a problem in terms of performance such that the manufacturing process becomes complicated and a problem occurs in dispersibility at the time of spraying the spacer. JP-A-63-89
Colored fine particles of a metal oxide or a metal hydroxide as shown in 408 have been proposed, but there is a problem that the alignment film is damaged and the quality of the liquid crystal display element is deteriorated because of high surface hardness.

The present invention solves the above problems,
The purpose is to provide colored spherical fine particles having extremely excellent chemical resistance and heat resistance, and to provide a high-quality liquid crystal display device using the colored fine particles.

[0005]

The present invention is a cured spherical fine particle of an amino resin having an average particle size of 0.1 μm or more and 50.0 μm or less and a standard deviation of particle size distribution of 10% or less of the average particle size. The present invention also relates to a colored fine particle characterized in that the inside of the fine particle is dyed with an acid dye, a method for producing the same, and a liquid crystal display device produced using the colored fine particle.

More specifically, the average particle diameter is 0.1 μm.
The solubility of the cured spherical fine particles of the amino resin having a particle size distribution of 50.0 μm or less and a standard deviation value of the particle size distribution of 10% or less of the average particle size is 5 parts by weight or more with respect to 100 parts by weight of water and water. A colored spherical fine particle obtained by dyeing with an acid dye in the temperature range of 70 to 250 ° C. in the presence of a solvent selected from one or more organic solvents, The present invention relates to a manufacturing method thereof, and the above-mentioned problems can be solved by forming a liquid crystal display element using the colored fine particles as a spacer.

The details of the present invention will be described below.

The colored fine particles of the present invention have an average particle size of 0.
A colored fine particle characterized in that the inside of cured spherical fine particles of an amino resin having a particle size distribution standard deviation value of 1 μm or more and 50.0 μm or less and 10% or less of the average particle diameter is dyed with an acid dye. It has excellent chemical resistance and heat resistance as compared with fine particles whose only surface is colored.

Cured spherical fine particles of amino resin having an average particle size of 0.1 μm or more and 50.0 μm or less and a standard deviation value of the particle size distribution of 10% or less of the average particle size used in the present invention are acetoguanamine, benzoguanamine and cyclohexyl. It is a cured spherical fine particle of an amino resin obtained from one or more kinds selected from the group consisting of carboguanamine, cyclohexene carboguanamine, norbornene carboguanamine, paratoluene sulfonamide, melamine and urea, and formaldehyde. Preferably,
A cured spherical fine particle of an amino resin obtained from one or more kinds selected from the group consisting of benzoguanamine, melamine and cyclohexylcarboguanamine, and formaldehyde.

Cured spherical fine particles of amino resin having an average particle size of 0.1 μm or more and 50.0 μm or less and a standard deviation value of particle size distribution of 10% or less of the average particle size used in the present invention are disclosed in, for example, JP-A-62-62. It can be created by the method of -68811. When the standard deviation of the particle size distribution of such particles is larger than 10% of the average particle size, it becomes difficult to obtain a liquid crystal display device having good display quality. When used for a liquid crystal display device, the average particle size is 1.0 to 20.0 μm.
Spherical particles are preferred.

The acid dye used in the present invention may be any one as long as the dye ion becomes an anion in an aqueous solution,
Specific examples include anthraquinone type, azo type, and nigrosine type. The reason why acid resistance improves the chemical resistance is not clear, but acid dyes do not contain -N in amino resins.
-R ₁ R ₂ (R ₁ and R ₂ are each independently H, CH ₂ O
_{H, CH 2 OCH 2 N-,} CH 2 N- represents a) very high affinity, it is considered to uniformly and firmly attached to the amino resin matrix. The acid dye is more preferably an acid dye having an amino group in the dye molecule. The reason for this is not clear, but when the cured spherical fine particles of the amino resin are dyed, the unreacted methylol group in the cured spherical fine particles of the amino resin reacts with the amino group in the dye molecule,
It is presumed that the chemical resistance is further enhanced.

The solvent used in the method for producing colored fine particles of the present invention has water and / or water solubility of 10%.
One or two or more solvents selected from one or two or more organic solvents that are 5 parts by weight or more based on 0 parts by weight. Preferably, water, acetone, methyl alcohol,
One or more selected from ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol.

The temperature range of dyeing in the method for producing colored fine particles of the present invention is a temperature range of 70 to 250 ° C. More preferably, it is dyed in a temperature range of 100 to 180 ° C. If the temperature is lower than 70 ° C, the dyeability in the amino resin is lowered, and it becomes difficult to obtain good colored fine particles. Also,
If the temperature exceeds 250 ° C, the cured spherical fine particles of the amino resin may be softened or decomposed, which is not preferable. Also,
When dyeing at a temperature higher than the boiling point of the solvent, it is necessary to dye in a closed container such as an autoclave. By this method, the internal pressure in the closed container is increased and the dye can be dyed inside the particles.

In the method for producing colored fine particles of the present invention, the crosslinking reaction of the amino resin proceeds at the same time as dyeing, the dye can be contained in the crosslinked stitch, and the chemical resistance can be enhanced.

In the method for producing colored fine particles of the present invention, a dyeing aid may be used to accelerate dyeing. Further, in order to further improve the crosslink density of the fine particles after dyeing, a curing reaction can be further promoted by a conventional method using a catalyst and aldehydes such as formaldehyde.

The colored fine particles produced by the method for producing colored fine particles of the present invention contain the above acid dye in an amount of 1 per weight of the colored fine particles.
It can contain up to 15% by weight. If it is less than 1% by weight, the degree of coloring may be small, and if it is more than 15% by weight, the crosslink density of the fine particles does not increase and the strength of the particles decreases, or the dye easily elutes due to chemical attack. Sometimes.

By the above method, the acid dye to be dyed can be made to exist even inside the fine particles. The uniformity of the dye can be confirmed by thinly slicing the colored fine particles with a microtome or the like and observing with a microscope.

The colored fine particles obtained in the present invention can be used as a spacer for a liquid crystal display device as shown in FIG. In particular, it can be effectively used as a spacer for a liquid crystal display device with a backlight such as a cold cathode tube or an EL lamp for achieving high contrast.

Examples of the present invention will be shown below, but the present invention is not limited to these examples.

[0020]

Example 1 A four-necked flask was charged with 75 parts of melamine, 75 parts of benzoguanamine, 290 parts of formalin having a concentration of 37% and 1.16 parts of a sodium carbonate aqueous solution having a concentration of 10% to prepare a mixture, and the pH of the system was adjusted to 8.0. Prepared. This mixture was heated to 90 ° C. with stirring and reacted at the same temperature for 1.5 hours to obtain an initial condensate having a water miscibility of 200%. Separately, 5.5 parts of nonionic surfactant Emulgen 430 (manufactured by Kao, polyoxyethylene oleyl ether) was added to 24 parts of water.
It is dissolved in 55 parts and the temperature of this surfactant solution is adjusted to 5
The temperature was raised to 0 ° C. and the mixture was stirred. The above-mentioned initial condensate was added to a surfactant aqueous solution under stirring to obtain an emulsion of the initial condensate. To this was added 90 parts of a 5% aqueous solution of dodecylbenzenesulfonic acid, and the mixture was held at a temperature of 50 to 60 ° C. for 3 hours for condensation curing to obtain an emulsion of a cured resin. Add this emulsion to cold water 3
It was put into 000 parts and rapidly cooled. Then, the paste obtained by separating the hardened resin from the emulsion by sedimentation was placed in an aqueous solution obtained by dissolving 7.5 parts of Emulgen 430 and 4.5 parts of dodecylbenzenesulfonic acid in 2000 parts of water. Dispersion was performed using an ultrasonic disperser. The emulsion obtained by dispersion was gradually heated to 85 ° C. with stirring and then cooled to 30 ° C. The cured resin was separated from the emulsion by sedimentation.
The particle size distribution of this cured resin is measured by a particle size distribution measuring device (coulter
Counter-C-1000, Coulter Electronics Inc.
The average particle size was 8.00 μm and the standard deviation was 0.32 μm, and when observed with an optical microscope (magnification: 600 times), they were spherical particles and were well transparent to light.

50 g of cured spherical fine particles of benzoguanamine / melamine / formaldehyde amino resin having an average particle diameter of 8.00 μm and a standard deviation of 0.32 μm, and Kayasil Skyble-R which is an anthraquinone acid dye.
(Nippon Kayaku Co., Ltd.) 10 g, pure water 450 g, and Catanit A (manufactured by Nitto Riken Co., Ltd.) 0.5 g, which is a latent curing catalyst for amino resin, were charged in a 2-liter autoclave. . After substituting with N ₂ , the temperature was raised to 170 ° C. and dyeing was carried out for 5 hours. After the completion of dyeing, the particles were separated by filtration, washed with pure water several times, dried and crushed.

The obtained particles are dyed in dark blue,
Light was blocked well. From the material balance before and after dyeing, it was confirmed that the particles contained 5% by weight of the dye. By using such colored fine particles, B
When an STN liquid crystal display device with a 5th size backlight was prepared, a liquid crystal display device having a higher contrast than a display device using a conventional spacer could be prepared. In addition, it worked well without dye elution.

[0023]

Example 2 The same procedure as in Example 1 was repeated except that 75 parts of melamine and 75 parts of benzoguanamine were changed to 150 parts of melamine and the reaction time at 85 ° C. was changed from 1.5 hours to 4 hours. 00 μm, standard deviation 0.22
True spherical hardened spherical fine particles of μm were obtained.

50 g of cured spherical fine particles of melamine / formaldehyde amino resin having an average particle diameter of 3.00 μm and a standard deviation of 0.22 μm, 5 g of a nigrosine-based acid dye w-45 (produced by Orient Chemical Co., Ltd.), Pure water 4
00 g and 50 g of ethanol were charged into a 2 liter autoclave. After substituting with N ₂ , the temperature was raised to 100 ° C. and dyeing was carried out for 8 hours. After the completion of dyeing, the particles were filtered off in the same manner as in Example 1, washed with pure water several times, dried and crushed.

The obtained particles were dyed black, and were well shielded from light. From the material balance before and after dyeing, it was confirmed that the particles contained 3% by weight of the dye. B5 is produced by a known method using such colored fine particles.
When a plate-sized ferroelectric liquid crystal display device with a backlight was prepared, a liquid crystal display device having a higher contrast than a display device using a conventional spacer could be prepared. In addition, it worked well without dye elution.

[0026]

Example 3 In Example 1, 75 parts of melamine and 75 parts of benzoguanamine were added to 150 parts of benzoguanamine,
The reaction time at 85 ° C was changed from 1.5 hours to 0.5 hours, and the surfactant was added from Emulgen 4307.5 parts to PVA205.
(Polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) Hard spherical spherical fine particles having an average particle size of 16.00 μm and a standard deviation of 1.15 μm were obtained in the same manner except that the content was changed to 2 parts.

50 g of cured spherical fine particles of benzoguanamine / formaldehyde amino resin having an average particle diameter of 16.00 μm and standard deviation of 1.15 μm, anthraquinone acid dye Kayacil cyanine green G (manufactured by Nippon Kayaku Co., Ltd.) ) 20 g, pure water 300 g and isopropyl alcohol 50 g were charged into a 2 liter autoclave. After substituting with N ₂ , the temperature was raised to 130 ° C. and dyeing was carried out for 12 hours. After the completion of dyeing, the particles were filtered off in the same manner as in Example 1, washed with pure water several times, dried and crushed.

The obtained particles are dyed in dark green,
Light was blocked well. From the material balance before and after dyeing, it was confirmed that the particles contained 10% by weight of the dye. A B5 plate-sized STN liquid crystal display device with a back light was prepared using such colored fine particles by a known method. As a result, a liquid crystal display device having a higher contrast than a display device using a conventional spacer could be prepared. In addition, it worked well without dye elution.

[0029]

Comparative Example 1 Average particle size obtained in Example 1 8.
Benzoguanamine with 00 μm and standard deviation 0.32 μm /
The cured spherical fine particles of melamine / formaldehyde amino resin were washed with pure water several times without being dyed, then dried and crushed. The obtained particles were transparent and transmitted light. When a B5 plate-sized STN liquid crystal display device with a back light having a size of B5 was prepared using such fine particles, the contrast was worse than that of the display device using the colored fine particles of this example and the display quality was deteriorated.

[0030]

Comparative Example 2 Colored fine particles were prepared in the same manner as in Example 1 except that the reaction temperature of the autoclave was changed from 170 ° C to 40 ° C. The colored fine particles obtained were hardly dyed and transmitted light well. By using such fine particles, a B5 plate-sized backlit S by a known method.
When a TN liquid crystal display device was produced, the contrast was worse and the display quality was lower than that of the display device using the colored fine particles of this example.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display device according to the present invention.

[Brief description of reference numerals]

 1, glass plate 2, seal resin 3, seal spacer 4, alignment film 5, transparent electrode 6, polarizing film 7, liquid crystal 8, colored particles

Claims (3)

(57) [Claims] 1. An average particle size of 0.1 μm or more and 50.0 μm
m or less and standard deviation of particle size distribution is 10% of average particle size
The following is a cured spherical fine particle of an amino resin, wherein the inside of the fine particle is dyed with an acid dye, which is a colored fine particle. 2. The average particle diameter is 0.1 μm or more and 50.0 μm.
m or less and standard deviation of particle size distribution is 10% of average particle size
70% by weight of the following cured spherical fine particles of amino resin in the presence of a solvent selected from the group consisting of water and / or an organic solvent having a solubility in water of 5 parts by weight or more based on 100 parts by weight of water: A method for producing colored fine particles, which comprises dyeing with an acid dye in a temperature range of 250 ° C. 3. A liquid crystal display device produced by using the colored fine particles according to claim 1.