JPH09208607A - Colored microparticle, its production, spacer for liquid crystal display and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce colored microparticles containing a well dispersed pigment, being capable of evenly coloring and having excellent mechanical strengths and solvent resistance and having proof against the elution of impurities from the pigment, to provide a process for its production, and to obtain a spacer for liquid crystal displays and a liquid crystal display element. SOLUTION: These particles are made from a polymerizable monomer and carbon black particles surface-coated to prevent the elution of impurities. The production process comprises uniformly dispersing surface-coated carbon black particles in a polymerizable monomer and subjecting the obtained dispersion to suspension polymerization in an aqueous medium. The spacer is made of the above particles. The display is made by using the spacer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a paint, a marking material,
The present invention relates to a colored fine particle used for a carrier for a diagnostic reagent, a spacer for a liquid crystal display element and the like, a method for producing the same, and a liquid crystal display element using the same.

[0002]

2. Description of the Related Art Colored fine particles are used in many fields as paints, labeling materials, diagnostic reagent carriers, spacers for liquid crystal display devices and the like. Such colored fine particles are generally produced by mixing a pigment such as carbon black with a polymer produced in advance. For example, after homogenizing the organic solvent liquid of the polymer and the pigment, spray drying is performed. A method of dispersing the polymer solution in water containing a pigment, removing the water and the solvent, and a method of kneading the polymer and the pigment and pulverizing.

However, in such a method, an apparatus and energy for removing the solvent are required, and the dispersed state of the pigment particles is not uniform in the polymer, and the obtained colored fine particles have an irregular particle shape. However, there was a problem that the particle size distribution was wide and it was not uniformly colored.

Japanese Patent Publication No. 50-33821, Japanese Patent Publication No. 5
6-50883 and Japanese Patent Publication No. 4-89805 disclose a method for producing colored fine particles by suspension-polymerizing a polymerizable monomer in the presence of a pigment. However, in this method, the type of the polymerizable monomer, there is a restriction in terms of the amount, since the pigment contained may be exposed on the surface of the fine particles, the pigment itself may be eluted by an organic solvent, Impurities in the pigment were sometimes eluted. Further, it is unsuitable for applications where it is required that no pigment is present on the surface of the fine particles, for example, when it is used as a carrier for adsorbing or binding biological substances such as proteins and enzymes.

In Japanese Patent Publication No. 4-59321, a monomer comprising a polyfunctional vinyl compound and a lipophilic vinyl compound is mixed with a lipophilic pigment, and the pigment is suspended in an aqueous medium. A method for producing colored fine particles by polymerizing is disclosed. However, with this colored fine particle,
Although an improvement in the dispersibility and solvent resistance of the pigment is recognized, in order to prevent the pigment from substantially existing on the surface of the colored fine particles, a vinyl compound is suspension-polymerized or emulsion-polymerized in a later step. However, there is a problem in that the production process becomes expensive because the polymerization process becomes two steps.

Japanese Unexamined Patent Publication (Kokai) No. 7-2913 discloses a method for producing colored fine particles by mixing a pigment with a crosslinkable monomer and carrying out suspension polymerization in an aqueous phase.
Although the dispersibility of the pigment, the mechanical strength of the fine particles and the solvent resistance are improved, impurities were eluted from the pigment used into the fine particles, and it was difficult to obtain uniformly colored fine particles.

[0007]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a pigment having good dispersibility, capable of uniformly coloring, and having good mechanical strength and durability. Excellent in solvent properties, colored fine particles capable of preventing the elution of impurities from the pigment and a method for producing the same, and
It is to provide a spacer for a liquid crystal display device and a liquid crystal display device.

[0008]

The above object can be achieved by colored fine particles composed of a polymerizable monomer and carbon black whose surface is coated to prevent elution of impurities.

The above object can also be achieved by a method for producing colored fine particles in which carbon black whose surface is coated is uniformly dispersed in a polymerizable monomer and then suspension polymerization is carried out in an aqueous medium. You can

The above object can be further achieved by a spacer for a liquid crystal display device comprising the above-mentioned colored fine particles and a liquid crystal display device using the spacer. Hereinafter, the present invention will be described in detail.

The polymerizable monomer used in the present invention is not particularly limited, and examples thereof include acrylic acid, methacrylic acid,
Maleic acid, maleic anhydride, fumaric acid, crotonic acid,
Unsaturated carboxylic acids such as itaconic acid; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate and 2-ethylhexyl acrylate Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, glycidyl methacrylate, β-methacrylic acid
Methacrylic acid esters such as hydroxyethyl and hydroxymethyl methacrylate; styrene, vinyltoluene,
Styrene-based monomers such as α-methylstyrene; vinyl acetate, vinyl propionate, acrylamide, methacrylamide, acrylonitrile, methylol acrylamide, vinyl stearate, acrylic acetate, diallyl adipate, dimethyl itaconate, diethyl maleate, allyl. Alcohol, vinylidene chloride, vinyl chloride,
Examples thereof include ethylene. These may be used alone or in combination of two or more.

Further, together with the above polymerizable monomer, any crosslinkable compound, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene and its derivatives; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, Trimethylolpropane triacrylate,
Di- or triethylenically unsaturated carboxylic acid ester such as 1,3-butanediol dimethacrylate; Divinyl compound such as N, N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfonic acid and 3 or more vinyl groups One kind or two or more kinds of compounds may be used. The amount of the crosslinkable compound used is 0.005 to the total amount of the compound and the polymerizable monomer.
100% by weight is preferred.

The carbon black used in the present invention is
The surface is coated with a thermoplastic resin or the like. The carbon black is not particularly limited, for example,
Examples include channel black, roll black, furnace black, thermal black and the like. The thermoplastic resin is not particularly limited, for example, alkyd resin,
Modified alkyd resin, phenol resin, natural resin modified phenol resin, maleic acid resin, natural resin modified maleic acid resin, fumaric acid resin, ester gum, rosin, petroleum resin, coumarone resin, indene resin, polyester resin,
Examples thereof include polyamide resin, polycarbonate resin, polyester resin, epoxy resin, styrene resin, vinyl resin, acrylic resin, chlorinated rubber, benzoguanamine resin, and urea resin. These may be used alone or in combination of two or more.

The method of coating the surface of carbon black with the above-mentioned thermoplastic resin is not particularly limited, and for example, carbon black is finely powdered in a hydrophobic medium containing the above-mentioned thermoplastic resin by using a grinding machine such as a ball mill. A method of emulsifying, adding and mixing an aqueous dispersion of carbon black in a hydrophobic medium containing the thermoplastic resin and emulsifying, then distilling water by heating, preheating the hydrophobic medium containing the thermoplastic resin Then, a method of adding water dispersion of carbon black and mixing and distilling water at the same time can be mentioned. The surface-coated carbon black obtained by the above method is ethanol, which can be mixed with a hydrophobic medium,
It can be precipitated by mixing a lower alcohol such as isopropanol, and can be recovered by filtration, decantation or the like.

The colored fine particles of the present invention can be obtained by polymerizing the above-mentioned polymerizable monomer and the above-mentioned carbon black whose surface is coated. The polymerization method is not particularly limited, and examples thereof include suspension polymerization and emulsion polymerization. Among them, suspension polymerization is preferable in order to obtain uniformly colored colored fine particles. The suspension polymerization is performed in an aqueous medium after uniformly dispersing the surface-coated carbon black in the polymerizable monomer.

The amount of the above-mentioned polymerizable monomer blended is such that the aqueous medium 1
1 to 200 parts by weight is preferable with respect to 00 parts by weight. 1
If it is less than 100 parts by weight, it is industrially disadvantageous, and if it exceeds 200 parts by weight, it becomes difficult to remove the heat of polymerization. The amount of the carbon black coated on the surface is preferably 0.1 to 200 parts by weight with respect to 100 parts by weight of the polymerizable monomer. If it is less than 0.1 part by weight, it will be difficult to be colored deeply, and if it exceeds 200 parts by weight, the mechanical strength of the obtained colored fine particles may decrease.

To uniformly disperse the surface-coated carbon black in the polymerizable monomer, for example,
Ball mill, bead mill, sand mill, attritor,
A sand grinder, a nanomizer, etc. can be used. In this case, a known dispersant may be added in order to enhance the dispersibility of the surface-coated carbon black.

The aqueous medium is not particularly limited, and examples thereof include polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, gelatin, methyl cellulose, polymethacrylamide, polyethylene glycol, polyethylene oxide monostearate, sorbitan tetraoleate, glycerin mono. Examples thereof include aqueous solutions of water-soluble organic compounds such as oleate and dodecylbenzenesulfonic acid.

The polymerization temperature of the above suspension polymerization is 30 to 95 ° C.
Is preferred. If the temperature is lower than 30 ° C, the polymerization rate is low,
When it exceeds 95 ° C, it becomes difficult to control the polymerization reaction. The polymerization time of the above suspension polymerization is preferably 1 to 50 hours. When the time is less than 1 hour, the polymerization rate is low, and the time exceeding 50 hours is unnecessary.

The colored fine particles obtained by the above suspension polymerization can be separated by means such as filtration and centrifugation.
The separated colored fine particles are washed with water or the like and then dried by heating or reduced pressure to obtain a product of colored fine particles.

In the above suspension polymerization, if necessary,
A polymerization initiator may be added to the aqueous medium. The above-mentioned polymerization initiator is not particularly limited and includes, for example, 2,2′-
Azobisisobutyronitrile, 2,2'-azobis-
Azonitrile compounds such as 2,4'-dimethylvaleronitrile, 2,2'-azobis-methylbutyronitrile and 2,2'-azobis-methylheptonitrile; acetyl peroxide, decanoyl peroxide, lauroyl peroxide, Benzoyl peroxide, p-chlorobenzoyl peroxide, 2,
4-dichlorobenzoyl, diisopropyl peroxide carbonate,
2-Ethylhexyl dicarbonate peroxide, Acetylcyclohexylsulfonyl peroxide, t-Butyl perisobutyrate, t-Butyl perbivalate, t-Butyl 2-ethylhexanoate
Examples include organic peroxides such as -butyl, di-t-butyl peroxide, t-butyl cumyl peroxide, and dicumyl peroxide.
The amount of the polymerization initiator added is 0.05 to 30 parts by weight with respect to 100 parts by weight of the polymerizable monomer. When it is less than 0.05 parts by weight, the polymerization rate is low, and an amount exceeding 30 parts by weight is unnecessary.

The particle size of the colored fine particles of the present invention is 0.01 to.
5000 μm is preferable. If less than 0.01 μm,
It is easy to aggregate, and it is rare that a material having a diameter of more than 5000 μm is used.

The surface of the colored fine particles of the present invention may be coated with a silane coupling agent or the like, if necessary.
The silane coupling agent is not particularly limited, and examples thereof include γ-aminopropyltrimethoxysilane and N-β.
-(Aminoethyl) -γ-aminopropyltrimethoxysilane, 3- [N-allyl-N- (2-aminoethyl)] aminopropyltrimethoxysilane, 3- (N-
Amino-based silane coupling such as allyl-N-glycidyl) aminopropyltriethoxysilane, 3- (N-allyl-N-methacryl) aminopropyltrimethoxysilane, 3- (N, N-diglycidyl) aminopropyltrimethoxysilane Agents; N, N-bis [3- (methyldimethoxysilyl) propyl] amine, N, N-bis [3-
(Trimethoxysilyl) propyl] amine, N, N-bis [3- (methyldimethoxysilyl) propyl] ethylenediamine, N, N-bis [3- (trimethoxysilyl) propyl] ethylenediamine, N-glycidyl-
Amide silane coupling agents such as N, N-bis [3- (methyldimethoxysilyl) propyl] amine and N-glycidyl-N, N-bis [3- (trimethoxysilyl) propyl] amine; vinyltriethoxysilane , Vinyl-based silane coupling agents such as vinyl-tris (2-methoxyethoxy) silane; methacrylic-based silane coupling agents such as γ-methacryloxypropyltrimethoxysilane; glycidyl-based agents such as γ-glycidoxypropyltrimethoxysilane Silane coupling agents; mercapto-based silane coupling agents such as γ-mercaptopropyltrimethoxysilane and the like.

The method for coating the surface of the colored fine particles with the silane coupling agent is not particularly limited, and for example, the silane coupling agent and the colored fine particles are treated in an inorganic solvent such as water or an organic solvent such as alcohol. And then heated under stirring, after heating the colored fine particles are separated by decantation or the like, the solvent is removed by vacuum drying or the like, the silane coupling agent and the colored fine particles are directly mixed and heated, etc. Is mentioned.

The colored fine particles of the present invention can be suitably used as a spacer for a liquid crystal display device.

When the colored fine particles of the present invention are used as a spacer for a liquid crystal display device, the K value of the colored fine particles of the present invention is preferably 250 kgf / mm ² or more. If it is less than 250 kgf / mm ² , it may be difficult to accurately and stably maintain the distance between the pair of substrates of the obtained liquid crystal display element.

Here, the K value is a value defined by the following equation (1), which universally and quantitatively represents the hardness of a sphere. By using this K value, it becomes possible to quantitatively and uniquely express the suitable hardness of the colored fine particles of the present invention when the colored fine particles of the present invention are used as a spacer for a liquid crystal display device.

K = (3 / √2) · F · S ^−3/2 / R ^−1/2 (1) (In the formula, F represents a load value (kgf) in 10% compression deformation of the colored fine particles. , S represents compressive displacement (mm), and R represents particle radius (mm).)

When the colored fine particles of the present invention are used as a spacer for a liquid crystal display element, the recovery rate after compression deformation of the colored fine particles of the present invention is preferably 30% or more. If it is less than 30%, the plastic deformation is too large, which may cause an inconvenience in the step of determining the distance between the pair of substrates of the obtained liquid crystal display element.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a liquid crystal display device using a spacer for a liquid crystal display device comprising colored fine particles of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the liquid crystal display element A is disposed between the pair of substrates 7 and 9 and between the pair of substrates 7 and 9 in order to keep the gap between the pair of substrates 7 and 9 constant. Spacers 8, a nematic liquid crystal 11 enclosed between the pair of substrates 7 and 9, a sealing member 10 filled around the pair of substrates 7 and 9, and the surfaces of the substrates 7 and 9 are covered. The polarized sheets 12 and 13 are formed.

The substrates 7 and 9 are made of transparent substrates 1 and 4 made of glass, and ITO (Indium-Tin-Oxi) is formed on one side of the substrates.
de) patterning the transparent electrodes 2 and 5 made of a film,
The surfaces of the transparent electrodes 2 and 5 and the transparent substrates 1 and 4 are covered with alignment control films 3 and 6 made of a polyimide film or the like. The alignment control films 3 and 6 are subjected to alignment control processing by rubbing.

The spacer 8 is the colored fine particles of the present invention having a K value within the above-mentioned predetermined range and a recovery rate after compression deformation within the predetermined range.

[0034]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Preparation of colored fine particles 60 parts by weight of tetramethylol methanetriacrylate,
20 parts by weight of divinylbenzene and acrylonitrile 20
12 parts by weight of carbon black whose surface was coated with polyethylene was added, and the carbon black whose surface was coated was uniformly dispersed using a bead mill for 48 hours. 2 parts by weight of benzoyl peroxide was uniformly mixed with the colored polymerizable monomer composition in which the carbon black coated on the surface was dispersed, and the mixture was added to 850 parts by weight of a 3% by weight aqueous solution of polyvinyl alcohol. After well stirring, the colored polymerizable monomer droplets were suspended in a fine particle having a particle size of about 3 to 10 μm with a homogenizer to obtain a suspension.

The obtained suspension was transferred to a 2 liter separable flask equipped with a thermometer, a stirrer and a reflux condenser, and heated to 85 ° C. while stirring in a nitrogen atmosphere,
The polymerization reaction was carried out for 7 hours, and the temperature was further raised to 90 ° C. and maintained for 3 hours to complete the polymerization reaction. Then, the polymerization reaction liquid was cooled, and the formed colored fine particles were filtered, sufficiently washed with water and dried to obtain 120 parts by weight of pigment-dispersed colored fine particles having a particle diameter of 3 to 10 μm. The obtained colored fine particles are classified,
Colored fine particles having an average particle size of 5.55 μm and a particle size variation coefficient of 2.48% were obtained. The K value of the obtained colored fine particles, the recovery rate after compression deformation, the blackness, and the impurity concentration in the colored fine particles were evaluated by the following methods, and the results are shown in Table 1.

Evaluation Method (1) K Value (i) Measuring Method At room temperature, the obtained colored fine particles were dispersed on a steel plate having a smooth surface, and one colored fine particle was selected from the powder. Next, using a micro compression tester (PCT-200 type, manufactured by Shimadzu Corp.), a diamond-made diameter of 50 μm was used.
The colored fine particles were compressed on the smooth end surface of the cylinder. At this time, the compression load was electrically detected as an electromagnetic force, and the compression displacement was electrically detected as a displacement due to the operating transformer.

As a result, the compressive displacement as shown in FIG.
The relationship of loads was calculated. As shown in FIG.
The load value and the compressive displacement in% compressive deformation were obtained, respectively. From these values and the above equation (1), the relationship between the K value and the compression strain as shown in FIG. 3 was obtained. However, the compressive strain is a value obtained by dividing the compressive displacement by the particle diameter of the colored fine particles and expressing it in%. (Ii) Compression speed This was performed by a constant load speed compression method. The load was increased at a rate of 0.27 grams weight per second (grf). (Iii) Test load The maximum load was 10 grf.

(2) Recovery Rate after Compressive Deformation (i) Measuring Method At room temperature, the obtained colored fine particles were dispersed on a steel sheet having a smooth surface, and one colored fine particle was selected from them. Next, using a micro compression tester (PCT-200 type, manufactured by Shimadzu Corp.), a diamond-made diameter of 50 μm was used.
The colored fine particles were compressed on the smooth end surface of the cylinder. At this time, the load was electrically detected as an electromagnetic force, and the compression displacement was electrically detected as a displacement due to the operating transformer.

As shown in FIG. 4, after compressing the colored fine particles to the reversal load value (shown by curve a in FIG. 4), the load was decreased conversely (shown by curve b in FIG. 4). . At this time, the relationship between the load and the compressive displacement was measured. However, the end point in the unloading was not the load value of zero but the origin load value of 0.1 g or more. Recovery rate is the displacement L to the point of reversal
₁ and displacement difference L from the point of reversal to the point where the origin load value is taken
It was defined as a value showing a ratio of ₂ (L ₂ / L ₁₎ in%.

(Ii) Measurement conditions Reverse load value 1 grf Origin load value 0.1 grf Compression rate under load and unload 0.27 grf / sec Measuring chamber temperature 20 ° C.

(3) Blackness The obtained colored fine particles were visually observed for blackness, and dark black ones were marked with ⊚ and light black ones were marked with x.

(4) Impurity Concentration in Colored Fine Particles Sodium ions present in the obtained colored fine particles,
Each concentration of potassium ion, chlorine ion, sulfate ion,
It was measured by ion chromatography.

Production of Liquid Crystal Display Device On a glass plate having a thickness of 0.7 mm, an indium oxide film having a thickness of about 500 Å was formed by a low temperature sputtering method.
After forming the tin oxide-based transparent conductive film, a predetermined electrode pattern was formed by photolithography. Then
After applying an aligning agent on this, a heated alignment control film was formed. Next, this glass plate was cut into a size of 5 cm × 12.5 cm to obtain a glass substrate of a liquid crystal display element.

An epoxy adhesive mixed with a glass fiber spacer was printed with a width of 1 mm on the periphery of the obtained glass substrate by screen printing. After the glass substrate was placed horizontally, the colored particles of the high molecular weight polymer were scattered from above by pressurized nitrogen gas and uniformly dropped onto the glass substrate. The application time was adjusted so that the application concentration of the polymer colored fine particles on the glass substrate was about 100 particles / mm ² .

Another glass substrate was superposed on the glass substrate on which the high-molecular polymer colored fine particles were dispersed, and then a load of 1 kg / cm ² was applied by a pressing machine so that the entire glass substrate was uniformly applied. . At the same time, this one at 160 ℃
20 minutes to heat the surrounding epoxy adhesive. After the inside of the cell thus manufactured was sucked to form a vacuum, liquid crystal was injected into the inside from a hole provided in a part of the peripheral seal portion to manufacture a liquid crystal display element.

As a result of measuring the gap value between the upper and lower substrates of the obtained liquid crystal display element, the gap value was 6.36 ± 0.0.
It was 3 μm. Polarizing sheets were attached to both upper and lower surfaces of the liquid crystal display element so that the color tone of the reflected light applied to the obtained liquid crystal display element exhibited an olive color. At this time, the olive color was uniform and no uneven color was observed in the density.
The electric resistance of the obtained liquid crystal display device and the display contrast of the image were evaluated by the following methods, and the results are shown in Table 1.
It was shown to.

Evaluation Method (1) Electric Resistance The resistance between the electrodes of the obtained liquid crystal display element was measured by the fine particle filling cell method. (2) Image Display Contrast The obtained liquid crystal display device is connected to a power source and turned on, and the display contrast of the image is visually observed. A sample having a good image display contrast is marked with ⊚, and a display contrast is poor. Some were marked as x.

Examples 2 to 4 Colored fine particles and a liquid crystal display device were prepared and evaluated in the same manner as in Example 1 except that the compounding amounts shown in Table 1 were used, and the results are shown in Table 1. .

Comparative Example 1 A carbon black whose surface was not coated was used, and Table 1
Colored fine particles and a liquid crystal display device were produced and evaluated in the same manner as in Example 1 except that the compounding amount shown in Table 1 was used, and the results are shown in Table 1.

Comparative Example 2 Colored fine particles were prepared in the same manner as in Example 1 except that the carbon black was not compounded and the compounding amounts shown in Table 1 were used.
A liquid crystal display device was prepared and evaluated, and the results are shown in Table 1.

[0052]

[Table 1]

[0053]

EFFECTS OF THE INVENTION Since the colored fine particles and the method for producing the same of the present invention are as described above, the impurities of carbon black do not elute into the colored fine particles and have a uniform and thick black color, and the mechanical strength and resistance It is possible to obtain colored fine particles having excellent solvent properties, and when used as a coating material, a labeling material, a carrier for a diagnostic reagent, a spacer for a liquid crystal display device, etc., the impurities of carbon black do not elute from the colored fine particles, and thus are suitable. Can be used. In particular, when it is used as a spacer for a liquid crystal display element, it is possible to prevent a decrease in display contrast of the liquid crystal display element.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one form of a liquid crystal display element of the present invention.

FIG. 2 is a graph showing the relationship between load and compressive displacement of colored fine particles.

FIG. 3 is a graph showing the relationship between the K value and the compression strain of colored fine particles.

FIG. 4 is a diagram illustrating a method of measuring a recovery rate of a colored fine particle after compression deformation.

[Explanation of symbols]

 1. Transparent substrate 2. Transparent electrode 3. Alignment control film 4. Transparent substrate 5. Transparent electrode 6. Alignment control film 7. Substrate 8. Spacer 9. Substrate 10. Seal member 11. Nematic liquid crystal 12. Polarizing sheet 13. Polarizing sheet

Claims (4)

[Claims] 1. Colored fine particles comprising a polymerizable monomer and carbon black whose surface is coated to prevent elution of impurities. 2. A method for producing colored fine particles, which comprises uniformly dispersing a surface-coated carbon black in a polymerizable monomer, and then carrying out suspension polymerization in an aqueous medium. 3. A spacer for a liquid crystal display device, which comprises colored fine particles composed of a polymerizable monomer and carbon black whose surface is coated to prevent elution of impurities. 4. A liquid crystal display device using the spacer for a liquid crystal display device according to claim 3.