JP2006182818A - Manufacturing method of carbon black for black matrix and carbon black for black matrix - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon black production method excellent in dispersion performance in a resin composition for forming a black matrix and suitable for black matrix formation, and carbon black produced by the production method.
A method for producing carbon black for a black matrix, characterized in that a slurry in which carbon black is dispersed in an oxidizing agent aqueous solution is subjected to oxidation treatment while being pulverized by a high-pressure homogenizer, then purified and dried. And carbon black produced by this production method,
(1) The ratio Dupa50% / Dst between the Stokes mode diameter Dst (nm) of the aggregate and the average particle diameter Dupa50% (nm) of the agglomerate is 2.0 or less,
(2) The carboxyl group on the surface of the carbon black particles is 1.1 to 8.0 μmol / m ² per external specific surface area STSA of the carbon black particles,
Carbon black for black matrix, characterized by
[Selection figure] None

Description

  The present invention relates to a method for producing carbon black for forming a black matrix used for a color filter for liquid crystal displays, and a carbon black for forming a black matrix.

  A liquid crystal display uses a combination of a reflector and a polarizing plate to control the transmission of incident light by sandwiching a crystal material that becomes liquid crystal between transparent electrodes and applying a voltage between the electrodes to change the molecular arrangement of the liquid crystal. This color liquid crystal display, which displays images and text, is a color LCD that uses red, blue, and green color filters for each pixel to create the three primary colors of light, and controls the brightness of each pixel. To express color changes.

  That is, a color liquid crystal display produces three primary colors of light on a transparent substrate through a color filter layer of red, blue, and green for each pixel, and controls the amount of light transmitted through each pixel to perform color display by coloring by adding the three primary colors. A blocking layer (black matrix) is formed to block light between pixels in order to prevent light leakage between the pixels to improve contrast and prevent a decrease in color purity. The black matrix also has a function of shielding a transistor circuit such as a liquid crystal driving electrode and a TFT (thin film transistor) provided on a substrate facing the color filter.

  Therefore, the black matrix is naturally required to have excellent light-shielding properties, but it must also have a smooth surface, thin layer thickness, low electrical conductivity and high insulation. It is said that. That is, when the surface smoothness is inferior and the layer thickness is thick, irregularities are generated when forming the color pattern of the three primary colors, and when the conductivity is high, the semiconductor element may malfunction due to the applied voltage. Because.

  Conventionally, (1) a black matrix made of a metal thin film of Cr, Ni, Al or the like by photolithography, and (2) a black matrix made of a black resin film in which a black pigment is dispersed in a resin, are used for this black matrix. I came. Among these, the black matrix formed of the metal thin film (1) has a high light shielding degree and optical density and is excellent in resolution, but is highly conductive and has a high light reflectance, so that reflection due to reflected light tends to occur. However, there is a problem that the display quality is impaired, and there is a problem that the cost is increased because the process is complicated.

  On the other hand, the black matrix comprising the black resin film in which the black pigment of (2) is dispersed in the resin has few of the above-mentioned disadvantages. In particular, carbon black has excellent blackness and light shielding properties as a black pigment. It has low conductivity and is suitable as a black pigment for black matrix.

  Therefore, a method of forming a black matrix by applying or printing a resin composition in which carbon black and a photopolymerizable resin are dispersed through an organic solvent on a transparent substrate surface, drying, and photopolymerizing has been developed. . However, since carbon black has poor dispersibility in resins and organic solvents, it is difficult to produce a uniformly and stably dispersed resin composition, making it difficult to form a uniform and thin resin film. In view of this, a technique using carbon black in which the surface properties of carbon black are modified to improve dispersibility in a photopolymerizable resin and an organic solvent has been developed.

For example, Patent Document 1 discloses that in an ink containing at least carbon black in a resin, the carbon black has an oil absorption of 40 to 130 ml per 100 g of carbon black, and the volatile loss when heated at 950 ° C. for 7 minutes. 3% by weight or more, and 10 to 50 parts by weight with respect to 100 parts by weight of the resin is disclosed. A resin black matrix obtained by dispersing a light-shielding agent in a resin, wherein carbon black satisfying at least one of the following (A) to (D) is used as the light-shielding agent. However, (A) PH value is 6.5 or less, (B) The carboxyl group concentration [COOH] on the surface is 0.001 <[COOH] as a molar ratio per total carbon atom, and (C) the hydroxyl group concentration on the surface. [OH] is the molar ratio per total carbon atom, 0.001 <[OH], (D) The surface sulfone group concentration [SO ₃ H] is 0.001 <[SO ₃ H].

Further, Patent Document 3 discloses a black matrix for a color filter, in which a black matrix containing carbon black as a black pigment has an average particle diameter of 40 to 300 nm. In the black matrix containing carbon black as a pigment, the carbon black is characterized in that the total oxygen amount calculated from CO and CO ₂ in the volatile matter at 950 ° C. is 7 mg or more per 100 m ² of the surface area of the carbon black. A black filter color filter resist comprising a carbon black having an average particle size of 50 to 200 nm and a DBP oil absorption of 10 to 40 ml / 100 g is disclosed in Patent Document 5, Patent Document 6 has an average of 1 There is disclosed a carbon black for forming a black resist pattern, characterized in that a carbon black having a secondary particle size of 35 to 150 nm, an aggregate diameter of 60 to 300 nm, and a dibutyl phthalate oil absorption of 30 to 90 ml / 100 g is coated with a resin. .

Further, Patent Document 7 discloses carbon black for an insulating black matrix obtained by coating carbon black having a total oxygen amount of 15 mg / g or more and a total oxygen amount / specific surface area of 0.10 mg / m ² or more with a resin, In Patent Document 8, at least one of the surface carboxyl group concentration [COOH], the surface hydroxyl group concentration [OH], and the surface sulfonic acid group concentration [SO ₃ H] is 0.005 in terms of a molar ratio per total carbon atoms. A resin black matrix comprising a resin containing a larger carbon black as a light-shielding agent and having a specific resistance of 7 × 10 ⁴ Ω · cm or more, Patent Document 9 discloses (A) the average primary particle diameter of 20 to 60 nm, DBP oil absorption of 30 to 100/100 g, specific surface area by the BET method: 30 to 150 m ² / g, a concentration of the carboxyl groups of the particle surface 0.2. [mu] mol / m ² of carbon black, (B) an amino group and / or copolymer having a quaternary ammonium salt thereof, and (C) a color filter black matrix resist carbon black, characterized in that it contains an organic solvent Dispersion liquid compositions have been proposed.

In addition, the present applicant has studied the performance improvement required for these black matrices from different viewpoints, and as a means of modifying the carbon black particle surface by grafting, the nitrogen adsorption specific surface area (N ^₂ SA) 50m ₂ / g or more, and wet oxidation of DBP absorption 140cm ^3/100 g or less of carbon black, the atomic ratio of the total oxygen atoms per total carbon atoms measured by X-ray photoelectron spectroscopy (oxygen binding energy Strength / carbon bond energy strength) For black matrix in which the functional group on the surface of carbon black oxidized to 0.1 or more is used as a base and the vinyl monomer is reacted and the vinyl polymer is chemically bonded by cationic polymerization. A carbon black pigment (Patent Document 10) was developed.

Furthermore, carbon for black matrix formed by converting the functional group on the surface of oxidized carbon black to an azo group to form a backbone, and a vinyl polymer formed by radical graft polymerization of a monomer containing a vinyl group on the backbone is chemically bonded. Black (Patent Document 11) was developed and proposed.
JP-A-8-262223 Japanese Patent Laid-Open No. 9-15403 Japanese Patent Laid-Open No. 9-15419 JP 9-22653 A Japanese Patent Laid-Open No. 9-80220 JP-A-11-80583 JP-A-9-95625 JP-A-9-265006 JP 2004-198717 A JP 2002-69327 A JP 2003-41149 A

  In general, the black matrix has high blackness and light shielding properties, has a high light shielding degree even when the light shielding layer is thin, and the surface of the light shielding layer is smooth and the conductivity of the light shielding layer is small. is needed.

  Fine pores exist on the surface of the carbon black particles, and these fine pores are likely to be formed especially when oxidized, while the inner surfaces of these fine pores are compatible with the resin medium. It doesn't really matter.

  Therefore, in order to improve the dispersion performance and blackness of carbon black in the resin composition, and to improve the performance of the black matrix, the present inventor has an important compatibility with carbon black and the resin medium, Considering that the surface properties of the aggregated particles of carbon black in contact with the resin medium are important, in relation to the aggregate structure of the basic particles of carbon black and the functional groups on the particle surface, the black matrix with carbon black as the black pigment We conducted earnest research on performance improvement.

  The present invention has been developed as a result of the above research, and its purpose is as a black pigment for forming a black matrix used in liquid crystal displays and the like, and it has excellent dispersion performance in a resin composition and is stable over a long period of time. A method for producing a black black for a black matrix, which maintains a dispersed state, has a low conductivity, and has a high light-shielding property, and a black black for a black matrix suitable for forming a black matrix produced by this production method. It is to provide.

  In order to achieve the above object, a method for producing carbon black for a black matrix according to the present invention comprises subjecting a slurry in which carbon black is dispersed in an oxidizing agent aqueous solution to oxidization while crushing with a high-pressure homogenizer, and then purifying And drying is a structural feature.

Further, the carbon black for black matrix according to the present invention is a carbon black produced by the above method,
(1) The ratio Dupa / Dst of the Stokes mode diameter Dst (nm) of the aggregate and the average particle diameter Dupa 50% (nm) of the agglomerate is 2.0 or less,
(2) The carboxyl group on the surface of the carbon black particles is 1.1 to 8.0 μmol / m ² per external specific surface area STSA of the carbon black particles,
This is a structural feature.

  According to the present invention, the dispersion performance in a resin composition for forming a black matrix used in a liquid crystal display or the like is excellent, a stable dispersion state is maintained over a long period of time, conductivity is low, and blackness is high. Thus, it is possible to provide a black matrix carbon black having a high light-shielding property and a black black carbon black suitable for forming a black matrix manufactured by this manufacturing method.

  There are no particular limitations on the carbon black that is the subject of the present invention, and furnace black, channel black, acetylene black, thermal black, and the like can be applied, but it is preferable to use furnace black that is excellent in productivity.

  As the oxidizing agent, for example, peroxodiacid salts such as peroxodisulfate, peroxodiborate, peroxodicarbonate, peroxodiphosphate, etc. are preferably used. Examples of peroxodiacid salts include alkali metal salts and ammonium salts. Etc. are preferable.

  The concentration of the oxidizing agent aqueous solution is preferably 0.1 to 50% by weight, and the concentration of carbon black dispersed in the oxidizing agent aqueous solution is preferably 3 to 25% by weight. Note that deionized water is preferable as the water for dissolving the oxidizing agent. Slurries in which carbon black is added to an aqueous oxidizer solution of a predetermined concentration and stirred and mixed at a temperature of 40 to 90 ° C. to disperse the carbon black to a predetermined concentration collide with each other as a high-pressure jet stream by a high-pressure homogenizer. Or it is made to collide with a wall surface.

  The aggregate of the carbon black particles in the slurry is crushed by the impact at the time of mutual collision or wall collision and the shearing force at the time of jetting. Further, the carbon black particle aggregate and the particle aggregate newly crushed by the frictional heat generated during the collision and shearing are uniformly and efficiently oxidized.

  In this case, the temperature of the slurry rises due to frictional heat. In this case, the temperature is preferably adjusted to a range of 40 to 90 ° C., and if necessary, the nozzle component is adjusted by heating or cooling. When the temperature is lower than 40 ° C., the oxidation treatment does not proceed sufficiently. On the other hand, when the temperature exceeds 90 ° C., the oxidation reaction proceeds at once, and it becomes difficult to control the oxidation treatment, and the temperature is preferably adjusted to 60 to 80 ° C.

  As the high-pressure homogenizer, various types of crushers such as a mutual collision type, a wall collision type, and a shear type that are commercially available are used. As the mutual collision type crusher, for example, a microfluidizer (manufactured by Microfluidic Corporation, trade name) ], An optimizer [made by Sugino Machine Co., Ltd., product name], nanomizer [made by Tokai Co., Ltd., product name], etc. Manufactured by Izumi Food Machine Nari Co., Ltd.).

  As shown in the flowchart of FIG. 1, the crushing and oxidation treatment by the high-pressure homogenizer is performed by first adding carbon black to the aqueous oxidizer solution at a predetermined ratio, and then at an appropriate temperature, for example, 40 to 90 ° C. in a mixing and stirring tank. Stir and mix thoroughly to prepare a slurry.

  The slurry is pressurized to, for example, about 50 to 250 MPa by a high-pressure pump, transferred to a crusher, and jetted as a high-speed jet from the jet nozzle, and the jet flow is subjected to mutual collision or wall collision and shearing force during jetting. The carbon black particle aggregate inside is crushed.

  The slurry crushed by the crusher is transferred to a storage tank mixing and stirring tank and stirred, then retransmitted to the mixing and stirring tank and stirred to maintain the dispersion state of the slurry stably. The slurry in the mixing and stirring tank is again transferred to the crusher, and the carbon black particle aggregates in the slurry are crushed again, and this circulation operation is repeated to crush to a desired state. In addition, you may perform repeatedly the circulation operation which transfers the slurry processed with the crusher directly to a mixing stirring tank, and does not pass through a storage tank mixing stirring tank, and injects it to a crushing machine.

  The slurry crushed by the high-pressure homogenizer and oxidized in this way is purified and dried to produce carbon black for the black matrix. In the purification, for example, residual salts in the slurry are removed by a separation membrane such as an ultrafiltration membrane (UF), a reverse osmosis membrane (RO), and an electrodialysis membrane, and then undispersed lump and coarse particles in the slurry are centrifuged or Remove and purify by means such as filtration.

  The refined slurry is concentrated to an appropriate concentration, for example, 3 to 50% by weight, and dried to produce carbon black for a black matrix. The drying is preferably performed by spray drying using a SK jet o mill, mist dryer, spray dryer, fluid medium tank, slurry dryer or the like.

The carbon black for black matrix of the present invention is produced by the above production method. (1) The ratio of the Stokes mode diameter Dst (nm) of the aggregate to the average particle diameter Dupa 50% (nm) of the agglomerate is Dupa 50% / Dst. 2.0 or less,
(2) The carboxyl group on the surface of the carbon black particles is 1.1 to 8.0 μmol / m ² per external specific surface area STSA of the carbon black particles,
It is characterized by having the following properties.

  The aggregate structure of the carbon black particles consists of aggregates (aggregates) in which the primary particles are fused and firmly bonded, and aggregates (agglomerates) in which the aggregates are secondarily aggregated due to entanglement and the like. Although it is difficult to release the aggregated structure because it is firmly bonded, agglomerate can release the aggregated structure relatively easily.

  Therefore, in the present invention, the agglomerate is crushed, and the ratio Dupa 50% / Dst ratio between the Stokes mode diameter Dst (nm) of the aggregate and the average particle diameter Dupa 50% (nm) of the agglomerate is crushed to 2.0 or less. To do. When the value of Dupa 50% / Dst exceeds 2.0, since the ratio of agglomerate aggregates is large, when a resin composition for forming a black matrix is prepared, long-term stable dispersion in the resin composition is achieved. This is because it is difficult to maintain. These values are values measured by the following method.

Measurement of the Stokes mode diameter Dst (nm) of the aggregate;
A carbon black sample dried according to JIS K6221 (82) 5 “How to make a dry sample” is mixed with a 20 vol% ethanol aqueous solution containing a small amount of a surfactant to obtain a carbon black concentration of 0.1 kg / m ^3. The sample is prepared and sufficiently dispersed with ultrasonic waves to obtain a sample. A disc centrifuging device (DCF; manufactured by Joyes Lobel, UK) was set to a rotation speed of 100 s ⁻¹ , and 0.015 dm ^{3 of} spin solution (2 wt% glycerin aqueous solution, 25 ° C.) was added, and then a buffer of 0.001 dm ³ A liquid (20% by volume ethanol aqueous solution, 25 ° C.) is injected. Next, after adding 0.0005 dm ³ of carbon black dispersion at a temperature of 25 ° C. with a syringe, centrifugal sedimentation was started, and at the same time, the recorder was operated, and the distribution curve shown in FIG. 2 (horizontal axis; carbon black dispersion with syringe) Elapsed time after addition in step, vertical axis; absorbance at a specific point changed with centrifugal precipitation of carbon black). Each time T is read from this distribution curve and substituted into the following equation (Equation 1) to calculate the Stokes equivalent diameter corresponding to each time.

In Equation 1, η is the viscosity of the spin liquid (0.935 × 10 ⁻³ Pa · s), N is the disk rotation speed (100 s ⁻¹ ), r ₁ is the radius of the carbon black dispersion injection point (0.0456 m). , the radius of r ₂ until the absorbance measuring point (0.0482m), ρ _CB is carbon black density ^{(kg / m 3), ρ} 1 is the density of the spin fluid (1.00178kg / m ^3).

  The maximum Stokes equivalent diameter in the Stokes equivalent diameter and absorbance distribution curve (FIG. 3) thus obtained is defined as the Stokes mode diameter Dst (nm) of the aggregate.

Measurement of agglomerate average particle size Dupa 50% (nm);
The concentration of carbon black in the slurry was adjusted to 0.1 to 0.5 kg / cm ³ and measured using a heterodyne laser Doppler type particle size distribution analyzer (UPA model 9340 manufactured by Microtrac). This measurement device measures the intensity of Brownian motion, that is, the particle diameter, from the degree of frequency modulation because the frequency of scattered light is modulated by the Doppler effect when laser light is irradiated onto particles that are in Brownian motion in suspension. To do. A cumulative frequency distribution curve is created from the particle diameters of the aggregates of carbon black particles measured in this manner, and the 50% cumulative frequency value of the cumulative frequency distribution curve is defined as the average particle diameter Dupa 50% (nm) of the agglomerate. .

Furthermore, the carbon black for black matrix of the present invention has a carboxyl group on the surface of the carbon black particles of 1.1 to 8.0 μmol / m ² per external specific surface area STSA of the carbon black particles in addition to the above aggregated structure. It is characterized by.

When carbon black is oxidized, various functional groups such as a carboxyl group, a hydroxyl group, and a quinone group are generated on the surface of the carbon black particles. Among these functional groups, the affinity for organic solvents such as propylene glycol monomethyl ether acetate and methoxybutyl acetate is high, and the carboxyl group is greatly involved in maintaining a stable dispersion state in the solvent. Therefore, in the present invention, the amount of carboxyl groups present on the surface of the carbon black particles is specified as 1.1 to 8.0 μmol / m ² per external specific surface area STSA.

By the oxidation treatment, fine pores are easily formed on the surface of the carbon black particles, and these fine pores hardly affect the dispersion performance at the interface. Therefore, dispersion performance is improved by using the external specific surface area STSA for measuring an external surface area not including fine pores of 20 angstroms or less, for example, instead of the nitrogen adsorption specific surface area (N ₂ SA) in which the area of the pore inner surface is also measured. It becomes possible to accurately evaluate the amount of carboxyl groups per unit surface area of the carbon black particles that greatly influence.

The reason for setting the amount of carboxyl group in the range of 1.1~8.0μmol / m ² is not sufficient to improve the dispersibility is less than 1.1μmol / m ^2, but exceed 8.0μmol / m ² This is because no significant effect is observed in improving dispersibility.

These characteristics are measured by the following method.
(A) External surface area (STSA);
Using an automatic specific surface area measuring device (manufactured by Shimadzu Corporation, Gemini 2375), measurement is performed in accordance with the method described in ASTM D5816-99 “Standard Test Methods for Carbon Black—External Surface Area by Multipoint Nitrogen Adsorption”.

(B) a carboxyl group;
After shaking the addition of carbon black 2~5g 6 hours in 0.976Mol / dm ³ sodium bicarbonate 0.5 dm ^3, was filtered carbon black from the reaction solution, 0.05 mol to the filtrate / dm ³ HCl After adding the aqueous solution, a neutralization titration test is performed with a 0.05 mol / dm ³ aqueous sodium hydroxide solution until the pH becomes 7.0 to quantify the carboxyl group.

  Thus, the carbon black for black matrix of the present invention is characterized in that the ratio of agglomerates which are secondary aggregates of carbon black particles is small and the aggregates are also small, and in addition, particles that affect the dispersion performance By specifying the amount of the carboxyl group on the surface by the external specific surface area not containing pores on the particle surface, it becomes possible to stably disperse the resin in the black matrix resin composition.

  Furthermore, since the average particle diameter of carbon black agglomerates is small, the thickness of the light shielding layer can be reduced, and a black matrix having high blackness and light shielding properties can be formed.

  The carbon black for black matrix of the present invention is a method of preparing a resin composition by mixing with an organic solvent and a resin, applying the resin composition to a transparent substrate by a spin coater, or applying a photoresist to the transparent substrate as a printing ink. A black matrix is formed by coating and baking the resin film by a method such as printing.

  Examples of the organic solvent include propylene glycol monomethyl ether acetate, methoxybutyl acetate, diethylene glycol monomethyl ether, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, benzene, chloroform, dichloromethane, ethyl acetate, methyl lactate, methyl lactate, methyl cellosolve. , Ethyl cellosolve, butyl cellosolve, methanol, ethanol, propanol, butanol, triethylene glycol, tetrahydrofuran, N-methyl-2-pyrrolidone, N, N'-dimethylformamide, N, N'-dimethylacetamide, N, N ' -Dimethyl sulfoxide or the like is used.

  Examples of the resin include heat resistance and fluidity such as acrylic resin, methacrylic acid resin, phenol resin, melamine resin, xylene resin, diallyl phthalate resin, cryptal resin, epoxy resin, alkylbenzene resin, polyester resin, and polyvinyl alcohol. An excellent photopolymerizable resin is used.

  The resin composition for forming a black matrix is prepared by mixing the carbon black of the present invention with an organic solvent and a resin. The mixing ratio is, for example, 2 to 20% by weight of carbon black, 60 to 96% by weight of the organic solvent. %, Resin in a ratio of 2 to 20% by weight.

  This is because if the proportion of carbon black is less than 2% by weight, the light-shielding property of the formed black matrix becomes low, while if it exceeds 20% by weight, the thickness of the black matrix becomes thick. Further, when the organic solvent is less than 60% by weight, the fluidity is remarkably lowered, so that it is difficult to form a black matrix having a uniform film thickness, and when it exceeds 96% by weight, the light shielding property is remarkably lowered. Further, if the resin is less than 2% by weight, the film strength of the black matrix decreases, and if it exceeds 20% by weight, the viscosity of the resin composition increases and it becomes difficult to control the film thickness.

  Examples of the present invention will be specifically described below in comparison with comparative examples.

Examples 1-4, Comparative Examples 1-2
100 g of carbon blacks having different external specific surface areas STSA and DBP oil absorption shown in Table 1 were mixed in a mixing and stirring tank shown in FIG. 1 together with ³ dm ^{3 of} sodium peroxodisulfate aqueous solution having different concentrations to prepare slurry.

  A high-pressure homogenizer (manufactured by Sanmaru Machinery Co., Ltd.) was used as a crusher, and the slurry was jetted at a pressure of 100 MPa to cause the jet streams to collide with each other. The slurry after the jetting collision was transferred to a storage tank mixing and stirring tank, cooled with stirring, and then retransmitted to the mixing and stirring tank. Thus, the circulation operation which injects a slurry and collides an injection flow mutually was performed repeatedly for 8 hours, and the crushing process and the oxidation process were performed to carbon black.

  Next, in order to purify the slurry, the remaining salt was removed by an ultrafiltration membrane [AHP-1010, manufactured by Asahi Kasei Co., Ltd., molecular weight cut off: 50000], followed by filtration and drying to produce a carbon black sample.

  With respect to these carbon black samples, the carboxyl group, the Stokes mode diameter Dst of the aggregate and the average particle diameter Dupa 50% of the agglomerate were measured, and the results are shown in Table 1.

Comparative Example 3
A carbon black sample was produced in the same manner as in Example 1 except that the slurry was stirred and mixed at a temperature of 60 ° C. and a stirring speed of 0.12 s ⁻¹ for 10 hours instead of crushing the slurry with a high-pressure homogenizer.

  Lightly mix 16g of these carbon black samples with 64g of propylene glycol monomethyl ether acetate as the organic solvent, 20g of acrylic resin as the resin, and 3g of Irgacure-907 (manufactured by Ciba Specialty Chemicals) as the photopolymerization initiator. After that, a resin composition for forming a black matrix was prepared by finely dispersing with a homogenizer. The degree of sedimentation and viscosity with time of this resin composition were measured by the following methods, and the results are shown in Table 2.

Sedimentation over time;
After producing the resin composition, the sedimentation state after standing for 1 month was observed.

viscosity;
The viscosity at a temperature of 298K was measured using a rotational vibration viscometer (manufactured by Yamaichi Denki, VM-100A-L).

The prepared resin composition was applied on a borosilicate transparent glass substrate having a thickness of 1.1 mm at a rotational speed of 0.06 s ⁻¹ using a spin coater, and then heat-treated on a hot plate having a temperature of 393 K for 120 seconds. Next, UV light is irradiated under a condition of 200100 ml / cm ² by an exposure apparatus (USHIO INC.) Through a mask having a line width of 20 μm (the portion that becomes a black matrix is 20 μm), and then a developer manufactured by Fuji Film Ohlin. The resin composition was cured by immersion in (FHD-5) and irradiation with ultraviolet rays. Thereafter, the film was immersed in a developer FHD-5 manufactured by Fuji Film Olin Co., Ltd., washed with a shower at a flow rate of 8.33 cm ³ / s and a discharge pressure of 0.098 MPa, and developed to remove the black resin layer in the non-exposed area. Finally, it was heated for 1 hour on a hot plate having a surface temperature of 523 K to form a black matrix pattern.

  The black matrix thus formed was measured and evaluated by the following method, and the results are shown in Table 3.

Coating surface electrical resistivity: Except that the glass substrate was changed to a chromium deposition substrate, a coating film was formed in the same manner as the black matrix, and a circular electrode having an area of 0.28 cm ² (S) was formed on the cured coating film using silver. A constant voltage (100 V) is applied using a constant voltage generator (Kenwood, PA36-2A, regulated DC power supply) between this electrode and the chrome vapor deposition surface as the counter electrode. The current (I) flowing through the membrane was measured with an ammeter (Advantest, R644C, digital multimeter). Next, the film thickness (d) cm of the black film was measured, and the volume resistivity R was calculated from the following formula.
R (Ω · cm) = (V · S) / (I · d)

Optical density (OD value);
A transmission optical density (OD value) was measured using a Macbeth densitometer (RD-927, manufactured by Kolmorgen), and an optical density per 1 μm of film thickness was determined.

Light sensitivity;
Evaluation was performed using a 41-step step tablet (manufactured by Kodak Co., No. 2) with an optical density of 0.00 as the first step and an optical density increasing by 0.05 at each step. The larger this value, the better the photosensitivity.

Film hardness;
The measurement was performed according to the method of JIS K5400 “Pencil scratch test”.

Surface roughness;
The surface was observed using SPM (scanning probe microscope, AFM mode, SPI-3100), and the surface roughness was measured.

Presence or absence of black matrix layer residue;
The state of removal of the black matrix layer in the non-exposed area by development was observed with an optical microscope.

  From the results of Tables 1, 2, and 3, Examples 1 to 4 were excellent in dispersibility of carbon black in the resin composition, and did not produce a precipitate even after standing for 1 month, and the viscosity was low. Further, the black matrix formed from this resin composition had good coating surface electrical resistivity, optical density, photosensitivity, film hardness, surface roughness, and no residue.

  In contrast, in Comparative Example 1, after preparing the resin composition, some of the particles floated in the initial stage, and after standing for one month, the color of the supernatant became transparent, and the black matrix formed with this resin composition Gave a residue. In Comparative Example 2, the resin composition hardly caused a precipitate even after standing for 1 month, but the viscosity was remarkably increased. In Comparative Example 3, which was stirred and mixed instead of crushing with a high-pressure homogenizer, a precipitate was formed in the resin composition after standing for 1 month. Thus, in the comparative example, the dispersion performance of carbon black in the resin was lowered.

It is the flowchart which illustrated the manufacturing process of carbon black for black matrices of the present invention. It is the distribution curve which showed the change of the light absorbency by the elapsed time after adding the carbon black dispersion liquid at the time of measurement of Dst, and carbon black centrifugal sedimentation. It is a distribution curve which shows the relationship between the Stokes equivalent diameter obtained at the time of measurement of Dst, and a light absorbency.

Claims (2)

  A method for producing carbon black for a black matrix, characterized in that a slurry in which carbon black is dispersed in an oxidizing agent aqueous solution is subjected to oxidation treatment while being pulverized by a high-pressure homogenizer, then purified and dried. A carbon black produced by the production method of claim 1,
(1) The ratio Dupa50% / Dst between the Stokes mode diameter Dst (nm) of the aggregate and the average particle diameter Dupa50% (nm) of the agglomerate is 2.0 or less,
(2) The carboxyl group on the surface of the carbon black particles is 1.1 to 8.0 μmol / m ² per external specific surface area STSA of the carbon black particles,
Carbon black for black matrix, characterized by

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