JP5080840B2 - Black complex oxide particles, black slurry, black paste, and black matrix - Google Patents

Description

The present invention relates to black composite oxide particles, and more specifically, blackness and electrical conductivity, as well as small primary particle size and aggregate particle size, and excellent ease of disaggregation of the aggregated particles. Black composite oxide with excellent blackness used especially for black matrix coloring composition, black electrode such as plasma addressed liquid crystal, light shielding layer formation, etc. It relates to physical particles.

Black pigments used in black matrix coloring compositions, black electrodes such as plasma displays and plasma addressed liquid crystals, and light-shielding layers are required to be excellent in properties such as blackness and electrical conductivity and inexpensive. ing. From this point of view, carbon black, iron oxide pigments such as magnetite, and other complex oxide pigments are used depending on applications.

  Of the above black pigments, the complex oxide pigments are excellent in blackness, oxidation resistance, and the like, and therefore, cobalt oxide alone or cobalt oxide oxide pigments have attracted attention. For example, Patent Document 1 discloses a composite black oxide particle composed of an oxide of cobalt, copper, and manganese whose composition is specified. Patent Document 2 discloses a composite oxide particle having a black color containing at least one or more of copper, nickel and molybdenum, and containing a specific amount of cobalt.

  By the way, the required characteristics required for the above black pigment are strict requirements for high performance and high quality in any application field. In addition to being excellent in light-shielding properties, a dense thin film is required for the formation of a light-shielding film. Accordingly, not only fineness of the particle size but also low aggregation and easy disaggregation of particles in black pigments. Is required. Further, there is a demand for particles having a uniform and suitable shape so as to ensure fine lineability when the electrode pattern is formed.

JP 2005-139063 A JP 2006-306712 A

With respect to the required characteristics in the above applications, Patent Document 1 proposes composite black oxide particles made of oxides of cobalt, copper, and manganese, and such particles have excellent blackness and particle shape. Is excellent in dispersibility in that it exhibits a granular shape, but is disadvantageous in terms of the above-mentioned use requiring high electrical resistance and electrical conductivity due to containing manganese.

  Patent Document 2 proposes a composite oxide particle having a black color and containing at least one or more of copper, nickel and molybdenum, and containing a specific amount of cobalt. Is excellent in terms of balance such as oxidation resistance, dispersibility at the time of coating, and surface smoothness of the coating when the coating is formed, but the particle shape is substantially plate-like Therefore, it is disadvantageous for securing the fine line property when the electrode pattern is formed. In addition, there is a concern that the agglomeration of the particles due to the large number of particle surface contacts, and there is a difficulty in lacking the pulverization property.

  As described above, as a black pigment mainly composed of a metal oxide, it is not only excellent in blackness and electrical conductivity, but also can form a dense thin film in the formation of a light-shielding film. No satisfactory material has yet been found for materials that have a uniform and suitable shape that is low in cohesion, easy to disaggregate, and can secure fine lineability when forming an electrode pattern. Is the actual situation.

  Accordingly, the object of the present invention is to provide a black composite oxide that satisfies the above-mentioned problems, which is suitable mainly as a black matrix coloring composition, a black electrode for a front plate of a plasma display, plasma addressed liquid crystal, etc. It is to provide physical particles.

  In response to the above problems, the present inventors have examined the components in the composite oxide particles, identified the particle shape, and found out the knowledge about the composite oxide particles in which the particle size of the primary particles and aggregated particles was controlled, and the present invention. Was completed.

That is, the black composite oxide particles of the present invention are composed of an oxide of cobalt and copper, the average primary particle diameter is 0.03 μm to 0.5 μm, and the D ₅₀ in the particle size measurement based on the number standard by the laser diffraction scattering method is 0. a .05Myuemu～1.0Myuemu, and shape and coloration granular, characterized in that it comprises 40 wt% to 65 wt% cobalt and 5 wt% to 30 wt% copper.

  The black composite oxide particles of the present invention have not only blackness and electrical conductivity, but also a primary particle size and a small aggregate particle size, and are excellent in easy disaggregation, and have fine lineability when formed into a paint and electrode pattern is formed. Since it can be ensured, it is suitable for black matrix coloring compositions, plasma displays, black electrodes on front plates such as plasma addressed liquid crystals, and black pigment powder for forming a light shielding layer.

Hereinafter, the present invention will be described based on preferred forms thereof.

The black composite oxide particles of the present invention are composed of an oxide of cobalt and copper, the average primary particle diameter is 0.03 μm to 0.5 μm, and the D ₅₀ in the particle size measurement based on the number standard by the laser diffraction scattering method is 0.05 μm. It is -1.0 micrometer, and a shape exhibits a granular form.

  The basic component of the black composite oxide particles of the present invention is an oxide composed of cobalt and copper. When components other than cobalt and copper of the present invention are contained, it can be seen that other properties required for various applications are affected. For example, if Mn or the like is contained in Patent Document 1, the electrical resistance increases. Therefore, even if it contains components such as Si, Al, Mn, Ni, Zn, Mg, Ti, Zr, W, Mo, and P as other components, for example, within a range that does not inhibit the effects of the present invention. Should be contained only.

  In addition, the amount of components of cobalt and copper contained in the black composite oxide particles of the present invention is such that the cobalt is 40 mass% to 65 mass%, and the copper is 5 mass% to 30 mass%, the blackness and electricity It is suitable because it is possible to obtain a stable granular black complex oxide particle having a fine particle size, low agglomeration property, and without inhibiting conductivity. More preferably, cobalt is 45% by mass to 60% by mass and copper is 10% by mass to 25% by mass, cobalt is 50% by mass to 60% by mass, and copper is 10% by mass to 20% by mass. % Is more preferable.

Further, the black composite oxide particles of the present invention have an average primary particle diameter of 0.03 μm to 0.5 μm, and a D ₅₀ in particle size measurement based on the number standard by the laser diffraction scattering method is 0.05 μm to 1.0 μm. In addition, the shape is granular.

Various properties of the black composite oxide particles vary depending on the components. In the case of a cobalt-copper complex oxide, the particle shape tends to be plate-like particles. Although it is possible to obtain granular, particularly spherical (including pseudo-spherical) particles, it is difficult to form aggregated particles, which is a drawback in the prior art.

On the other hand, the black composite oxide particles of the present invention are not only particles having a granular shape, but the aggregate primary particle size is an index of the aggregate particle size even though the average primary particle size is suitable for the intended use. Due to the fact that D ₅₀ in the particle size measurement based on the number criterion by a certain laser diffraction scattering method is also at a sufficiently small level, it has the property of easy degranulation, that is, the property that aggregation release proceeds rapidly.

When the average primary particle diameter is less than 0.03 μm, not only the color of the pigment becomes reddish, but the particles are too fine, resulting in significant aggregation of the particles and poor deflation. In addition, when the average primary particle diameter exceeds 0.5 μm, the particles are coarse, which not only hinders the securing of fine lineability when the intended use is used, but also has problems such as insufficient hiding power and coloring power as a pigment. Prone to occur. The average primary particle diameter is preferably 0.05 μm to 0.35 μm, more preferably 0.1 μm to 0.25 μm, and is a particle size suitable for the intended use, and hue, coloring power, and hiding power Easy to balance. This primary particle average diameter is measured by SEM observation.

Also, particles smaller than the D ₅₀ of 0.05μ, the small particle size of the primary particles, and is difficult realized than it is difficult to suppress aggregation, and thus exhibit even redness color pigments. Further, when D ₅₀ exceeds 1.0 μm, the aggregated particles are too large, or the primary particles are too large, so that the appearance of the coating film due to coating becomes difficult and the thin lineability is hindered. Not suitable for use. The D ₅₀ is preferably 0.08 μm to 0.8 μm, more preferably 0.1 μm to 0.7 μm, and other properties such as hue, coloring power, hiding power, etc. without impairing easy degranulation. Easy to balance.

Further, the black composite oxide particles of the present invention are characterized in that the particle shape of the black composite oxide particles is granular in addition to the specification of the primary particles and the aggregated particles. The term “granular” as used herein refers to a material having an isotropic shape such as a spherical shape, a pseudo-spherical shape, a polyhedral shape, etc., excluding those having an anisotropic shape or an indefinite shape such as a plate shape, a needle shape, etc. Aggregates (powder) in which 80% or more of the particles are occupied by granular particles are also regarded as granular particle powder.

As described above, in the case of a cobalt-copper composite oxide, the particle shape is easy to obtain a plate-like particle, and even if it is a granular particle, the particle size of the primary particle and the aggregated particle is not at the above level. Met. On the other hand, the black composite oxide particles of the present invention specify the component as cobalt-copper and control the particle size level and shape of the particles to be granular. In addition, it is possible to ensure fine lineability when forming the electrode pattern.

In the primary particles have an average particle size and the D _50, by the ratio D _{50 / (average} primary particle diameter), can show a degree of aggregation of the particles, it is preferred that the ratio is 1 to 4, 1 More preferably, it is ~ 3. The D _{50 / (average} diameter of primary particles) is (it is impossible theoretically take less than 1) is the in the above range, the degree of agglutination is sufficiently suppressed, not only can ensure the easy deagglomeration properties, Excellent hiding power and coloring power.

Further, the black composite oxide particles of the present invention preferably have a D _MAX of 4 μm or less based on the number standard by a laser diffraction / scattering particle size distribution measurement method. This D _MAX is an index indicating the degree of coarse particles in the aggregated particles, and this numerical value affects the coating properties when the pigment is used as a paint. Therefore, when D _MAX is within the above range, when the pigment is used as a paint, the influence of coarse particles is suppressed, and the appearance defect of the coating film is difficult to occur. When the D _MAX is preferably 3.5 μm or less, more preferably 2 μm or less, the coating film when used as a paint becomes more excellent in smoothness.

Also, the black complex oxide particles of the present invention, D ₉₀ based on the number value determined by a laser diffraction scattering particle size distribution measuring method preferably a 0.5Myuemu～2myuemu. This D ₉₀ is an index indicating the degree of aggregation on the larger particle size side in the entire aggregated particle, and the degree of aggregation can be seen by comparing with the D ₅₀ or D ₁₀ value. When this D ₉₀ is within the above range, the particle size level is low agglomeration and the primary particle size is not excessively refined or coarsened, and the pigment properties (blackness, hue, The hiding power, coloring power, etc.) are not impaired. The D ₉₀ is preferably 0.8 μm to 1.8 μm, and more preferably 1 μm to 1.6 μm, so that it is more excellent in easy degranulation and easily balances pigment properties.

  The crystal structure of the black composite oxide particles of the present invention is preferably a spinel type or an inverse spinel type in order to exhibit performance stability.

Also, the black complex oxide particles of the present invention, from the viewpoint of smoothness of the grained or particle surfaces of the particles, is preferably a specific surface area according to ^{BET 10m 2 / g~40m 2 / g} , more preferably ^{10 m} 2 / g It is good that it is ˜30 m ² / g.

Further, the black complex oxide particles of the present invention preferably have a tap density of 0.8 g / cm ^{3 to} 2.0 g / cm so that more particles can be mixed and dispersed in the vehicle that forms the paint at the time of coating. ^3, may more preferably at ^{0.8g / cm 3 ~1.6g / cm 3} .

The black composite oxide particles of the present invention preferably have a specific gravity of 6.0 g / cm ^{3 to} 7.0 g / cm ³ , more preferably 6.0 g / cm ^{3 in} order to improve initial dispersibility during coating. may is cm ³ ~ 6.8g / cm ^3.

In the black composite oxide particles of the present invention, since the aggregation is suppressed when the magnetic aggregation of the particles is smaller, the saturation magnetization is preferably 5 Am ² / kg or less, more preferably 3 Am ² / kg or less. good.

The black complex oxide particles of the present invention preferably have an electric resistance value of 10 ⁰ Ω · cm to 10 ³ Ω · cm, more preferably 10 ⁰ Ω · cm, in view of electrical conductivity required for the intended application. It is good that it is cm-10 ² Ω · cm.

The black composite oxide particles of the present invention have the characteristics described above, but the black composite oxide particles can be dispersed in various organic solvents to form a black slurry. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, glycol ethers such as cellosolve and carbitol, acetates such as ethyl acetate, and alcohols such as ethanol and propall. Aliphatic hydrocarbons such as octane and decane. As a distribution method, What is necessary is just to process using a media type stirring mill, a high-speed shearing type stirrer, etc. Moreover, in order to stabilize the dispersion state in a slurry, chemical | medical agents, such as surfactant, can be contained. Such a black slurry can be used mainly as a raw material for the black paste described below.

  Moreover, the black complex oxide particles can be blended with a film-forming component containing various resins and glass frit to form a black paste. Examples of the resin include acrylic resins, styrene resins, epoxy resins, polyester resins, and phenol resins. The glass frit having a low melting point and a particle size that can secure the thixotropy of a suitable paste is preferably selected in consideration of the particle size and content of the black composite oxide particles. Moreover, chemical | medical agents, such as surfactant and a coupling agent, can be contained for storage stability. The resin is preferably about 5 to 300 parts by weight and the glass frit is preferably about 5 to 200 parts by weight with respect to 100 parts by weight of the black composite oxide particles. Such a black paste is used in a form such as screen printing or offset printing to form a black matrix.

Next, a preferred method for producing the black composite oxide particles of the present invention will be described.
The black composite oxide particles of the present invention were prepared by neutralizing and mixing a metal salt mixed aqueous solution prepared using a water-soluble salt containing cobalt and copper and an alkali hydroxide, and the resulting metal hydroxide slurry was adjusted to pH 10. To 13 and oxidized at a temperature of 60 ° C. to 95 ° C. to obtain a precursor, and after solid-liquid separation of the obtained precursor, the solid content is heat-treated at a temperature of 400 to 700 ° C. for 1 hour and 3 hours or less. It is manufactured by doing.

First, a metal salt mixed aqueous solution is prepared using a water-soluble salt of cobalt and copper. The amount of cobalt salt and the amount of copper salt in the aqueous solution are preferably adjusted so that cobalt in the obtained black composite oxide particles is balanced to 40% by mass to 65% by mass and copper is 5% by mass to 30% by mass. .

  The cobalt and copper metal salts used in the preparation of the aqueous solution are not particularly limited as long as they are water-soluble, such as sulfates, nitrates, carbonates, chlorides, and the like, which are suitable for the liquidity of the reaction system. Use it. Further, the total metal ion concentration in the aqueous solution may be adjusted to about 0.5 to 2.0 mol / L in consideration of productivity and the like.

  Next, the mixed aqueous metal salt solution and the alkali hydroxide are mixed to produce a mixed hydroxide slurry.

  The alkali hydroxide used for this neutralization is preferably a caustic alkali such as sodium hydroxide or potassium hydroxide. The neutralization mixing may be any mixing mode, but it is preferable to add the metal salt mixed aqueous solution to the alkali hydroxide, and if the addition is performed for 30 to 120 minutes, the mixed hydroxylation with a uniform composition is performed. Core particles are obtained. If the addition time is shorter than 30 minutes, a non-uniform form of hydroxide is formed or amorphous particles are likely to be generated, and if it exceeds 120 minutes, a mixed hydroxide of a uniform composition is formed. However, the growth of the nuclei progresses, resulting in coarser grains than the intended grain size, or coarse grains become contaminated.

  Moreover, it is preferable to maintain slurry temperature at 50-90 degreeC in the case of the said mixing. When this temperature is less than 50 ° C., a hydroxide having a non-uniform composition may be formed when mixed with an alkali hydroxide to form a composite hydroxide. Further, when the temperature exceeds 90 ° C., the size of the nuclei is likely to be non-uniform, and the size of the finally obtained composite oxide particles is assumed to vary.

  The obtained mixed hydroxide slurry is adjusted in the range of pH 10 to 13, and an appropriate oxidizing agent (hydrogen peroxide, etc.) is added and an oxygen-containing gas, preferably air is blown into the black composite oxide in the slurry. Generate particles. The reaction temperature at this time is over 60 ° C. and 95 ° C. or less. When the reaction temperature is 60 ° C. or lower, the shape of the generated particles is easily plate-shaped, and it is difficult to obtain stable granular particles. On the other hand, when the reaction temperature exceeds 95 ° C., the desired granular particles can be obtained, but only the energy cost is increased more than necessary, which is uneconomical.

  The oxidation reaction is continued until the oxidation-reduction potential in the slurry reaches equilibrium, and the slurry thus obtained is further stirred at 80 to 100 ° C. for 1 to 6 hours or treated at 100 to 150 ° C. using an autoclave or the like. Then, the black composite oxide particles in the slurry may be aged.

  The slurry containing the black complex oxide particles that have been aged is subjected to conventional filtration, washing, and dehydration, followed by drying at 50 to 120 ° C. and then pulverization. Heat treatment is performed at 700 ° C. for more than 1 hour and 3 hours or less to stabilize the form. If the heat treatment time is 1 hour or less, the form of the oxide is not stable, and the hue may be deteriorated. On the other hand, if it exceeds 3 hours, the coloring power may be reduced due to the effect of inter-particle sintering.

Moreover, when the temperature at the time of heat processing is less than 400 degreeC, there exists a possibility that the form of an oxide may not be stable and stability of various characteristics may be lacking. Moreover, when it exceeds 700 degreeC, there exists a possibility that particle | grains may aggregate easily and an coloring power may become poor by an excessive heat load. Note that the atmosphere during the heat treatment may be in the air or in an inert gas atmosphere.
Since the black composite oxide particles obtained by the heat treatment may be partially aggregated, a conventional crushing treatment may be added.

Hereinafter, the present invention will be specifically described with reference to examples and the like.
[Example 1]
As shown in Table 1, 12 mol of cobalt sulfate and 4 mol of copper sulfate were dissolved in 10 liters of water (solution A). On the other hand, 10 liters of an aqueous sodium hydroxide solution having a pH adjusted to 11.5 was prepared (B solution). Next, liquid A was added to liquid B at a constant rate over 90 minutes. While maintaining the temperature during this addition at 60 ° C., 1N aqueous sodium hydroxide solution was appropriately added so that the pH of the mixed solution was 11.5. When the addition was completed, the liquid temperature was adjusted to 85 ° C., air was blown at a rate of 1 liter / min, and an oxidation reaction was performed for 2 hours to obtain precursor particles. Further, the obtained precursor particle slurry was aged for 2 hours while maintaining 85 ° C. The obtained slurry was filtered, washed and dried by a usual method to obtain a solid content. This solid content was heat-treated at 550 ° C. for 2 hours in an air atmosphere, thereby obtaining black composite oxide particles. The obtained particles were evaluated by the following methods. The results are shown in Table 2.

<Evaluation method>
(A) Particle shape and particle shape were observed with a primary particle average diameter scanning microscope (magnification 40,000 times). At the same time, the ferret diameter of 200 particles was arbitrarily measured, and the number average value was taken as the primary particle average diameter.
(B) D ₅₀ , D ₉₀ , D _MAX by laser diffraction scattering type particle size distribution measurement method
0.1 g of a sample was added to 100 ml of a sodium hexametaphosphate aqueous solution adjusted to 0.1%, and dispersed in a BRANSON 2200 (trade name) ultrasonic bath for 3 minutes. The dispersion was measured with LS-230 (trade name) manufactured by Beckman Coulter.
(C) D ₅₀ was measured when the dispersion time in the easy-defining property (d) of the aggregated particles was changed from 0 minutes to 6 minutes. The results are shown in FIG. 1 together with the results for 3 minutes.
(E) Specific surface area Measured with a 2200 type BET meter made by Shimadzu-Micromeritics.
(F) Cobalt and copper content with respect to the whole particle | grains The sample was melt | dissolved completely in the acid and content of cobalt and copper was calculated | required by ICP.
(G) Electric resistance 10 g of a sample was put in a holder, and after applying a pressure of 58.9 MPa to form a 25 mmφ tablet, an electrode was attached and measurement was performed under a pressure of 14.7 MPa. The electrical resistance value was calculated from the thickness and cross-sectional area of the sample used for the measurement and the resistance value.
(H) Blackness and hue The blackness of the powder was measured according to JIS K5101-1991.
Add 1.4 cc of castor oil to 2.0 g of sample and knead with Hoover-type Mahler. 7.5 g of lacquer is added to 2.0 g of this kneaded sample, and after further kneading, this is applied onto a mirror-coated paper using a 4 mil applicator, dried, and then a color difference meter (manufactured by Tokyo Denshoku Co., Ltd., Color Analyzer). Blackness (L value) and hue (a value, b value) were measured with TC-1800 type.
(I) Coloring power (evaluation of dispersibility and hue during coating)
Add 1.3 cc of castor oil to 0.5 g of black particles and 1.5 g of titanium oxide (R800 manufactured by Ishihara Sangyo Co., Ltd.), knead with Hoover-type Mahler, add 4.5 g of lacquer to 2.0 g of this kneaded sample, After further kneading, this was coated on a mirror-coated paper using a 4 mil applicator, dried, and measured for blackness (L value) with a color difference meter (Tokyo Denshoku Color Analyzer TC-1800). did.
(J) Tap density Measured with a powder tester PT-E type manufactured by Hosokawa Micron.
(K) Specific gravity Using a multi-volume density meter 1305 manufactured by Shimadzu Corporation, measurement was performed in an environment at room temperature of 20 ° C.
(L) Saturation magnetization Using a vibrating sample magnetometer VSM-P7 manufactured by Toei Industry Co., Ltd., measurement was performed with a load magnetic field of 796 kA / m.

[Examples 2-3, Comparative Examples 1 and 2]
As shown in Table 1, black complex oxide particles were obtained in the same manner as in Example 1 except that each production condition was changed. About the obtained black complex oxide particle, the place characteristic was evaluated similarly to Example 1. The results are shown in Table 2.

As is apparent from Table 2, the black composite oxide particles of the examples have a granular shape, a small average primary particle diameter, and D ₅₀ , D ₉₀ , and D _MAX each indicating the degree of aggregation. Relatively small. As a result, as shown in FIG. 1, without applying a mechanical load, it can be seen that the D ₅₀ is small, it is excellent in easy deagglomeration properties. Further, it has excellent blackness and electrical conductivity, and has various characteristics such as high tap density and low saturation magnetization.

On the other hand, the black composite oxide particles of the comparative example had a somewhat large primary particle average diameter, and the particles were non-granular. Although Comparative Example 1 was an oxide of cobalt and copper, D ₅₀ , D ₉₀ , and D _MAX indicating the degree of aggregation were large, and aggregation between primary particles was large. Therefore, as shown in FIG. 1, pulverization with a load of about the ultrasonic vibration is difficult. Moreover, it can be seen that each has inferior characteristics.

Is a diagram illustrating an easily deagglomeration property (change in D ₅₀₎

Claims (7)

It is made of an oxide of cobalt and copper, has an average primary particle size of 0.03 μm to 0.5 μm, D ₅₀ in particle size measurement based on the number standard by laser diffraction scattering method is 0.05 μm to 1.0 μm, and has a shape the granular and coloration,
Black composite oxide particles containing 40% to 65% by weight of cobalt and 5% to 30% by weight of copper . Black complex oxide particles according to claim 1, wherein the tap density of ^{0.8g / cm 3 ~2.0g / cm 3} . Black complex oxide particles according to claim 1 or 2, wherein the specific gravity of ^{6.0g / cm 3 ~7.0g / cm 3} . Black complex oxide particles according to any one of claims 1-3, wherein the saturation magnetization is less than 5Am ² / kg. The black slurry containing the black complex oxide particle in any one of Claims 1-4 . The black paste containing the black complex oxide particle in any one of Claims 1-4 . A black matrix formed from the black paste according to claim 6 .