JP4444061B2 - Composite black oxide particles, method for producing the same, black paint and black matrix - Google Patents

Description

  The present invention relates to composite black oxide particles, a method for producing the same, a black paint, and a black matrix, and more specifically, composite black oxide particles comprising oxides of cobalt, copper, and manganese, for paints, inks, and toners. Suitable for black pigments for rubber and plastics, especially for black matrix coloring composition, plasma display, black electrode on front plate such as plasma address liquid crystal, and light shielding layer formation, excellent blackness The present invention relates to a composite black oxide particle, a production method thereof, a black paint and a black matrix.

  Black pigments used in paints, inks, toners, rubbers and plastics, etc. are required to be excellent in properties such as blackness, hue, coloring power, hiding power, etc. and inexpensive. Carbon black Iron oxide pigments such as magnetite and other complex oxide pigments are used depending on the application.

In recent years, in addition to the demand for higher performance and higher quality in any of the above fields, for example, black pigments mainly composed of metal oxides are not only excellent in blackness but also black matrix. Oxidation resistance required during firing during formation, dispersibility in vehicle required when coating with resin or solvent, surface smoothness of coating film when coating the coating What is excellent in property etc. is calculated | required.
Representative examples of such black pigments mainly composed of metal oxides include single-component metal oxide particles such as cobalt oxide, manganese oxide, and copper oxide, Cu—Cr, Cu—Mn, and Cu—Cr. -Mn-based, Cu-Fe-Mn-based, Co-Mn-Fe-based, Co-Fe-Cr-based composite oxide particles, and the like.

JP-A-9-237570 Japanese Patent Laid-Open No. 10-231441

  In the metal oxide particles having a single composition, those having a large particle diameter have high blackness, but when they become submicron level particles, they are brown, or such particles are difficult to produce. To do.

Moreover, composite oxide particles also have advantages and disadvantages in terms of performance required for black pigments.
First, in the case of containing chromium as a component, such as Cu—Cr and Cu—Cr—Mn, it is difficult to produce particles of submicron level in addition to the problem of toxicity of chromium.

  In addition, in the case of the Cu—Mn system as disclosed in Patent Document 1, it is easy to make particles fine, but the shape is likely to be indefinite, the particles are likely to aggregate, and the dispersibility and coating when formed into a paint are also easily observed. The smoothness of the film is poor.

  Also, in the case of the Cu—Fe—Mn system as disclosed in Patent Document 1, the blackness is high, the shape is uniform, and the dispersibility is excellent, or Co as disclosed in Patent Document 2 is used. In the case of the -Mn-Fe system, the shape is uniform and the dispersibility is excellent. However, due to the fact that both contain iron (the blackness depends on Fe 2+, but easily deteriorates over time), it is said to be inferior in weather resistance and inferior in acid resistance. .

  As described above, as a black pigment mainly composed of a metal oxide, it is more excellent in blackness, oxidation resistance, dispersibility at the time of coating, and surface smoothness of the coating when the coating is formed. In fact, no satisfactory material has yet been found.

  Therefore, the object of the present invention is mainly suitable as a black pigment for paints, inks, toners, rubbers and plastics, and particularly for black matrix coloring compositions, plasma displays, plasma address liquid crystal and other front plates. Composite black oxide particles suitable for forming black electrodes and light-shielding layers, more excellent in blackness, oxidation resistance, dispersibility during coating, and surface smoothness of the coating when the coating is applied And a method of manufacturing the same.

  As a result of intensive studies on materials mainly composed of various metal oxides, the present inventors have found that specific Co—Cu—Mn based composite oxide particles can solve the above problems, and have completed the present invention.

That is, the composite black oxide particles of the present invention are composed of oxides of cobalt, copper, and manganese, the copper / cobalt molar ratio is 0.1 to 0.5, and the manganese / cobalt molar ratio is 0.
. It is 2 to 1.0.

  The black composite oxide particles according to the present invention are more excellent in blackness, oxidation resistance, dispersibility at the time of coating, and surface smoothness of the coating when the coating is formed. It is suitable as a black pigment for ink, toner and rubber / plastic. In particular, it is suitable for forming a black matrix coloring composition, a plasma display, a black electrode on a front plate such as a plasma address liquid crystal, and a light shielding layer. Moreover, the black matrix, plasma display, and plasma address liquid crystal formed by the black paint using such black composite oxide particles are excellent in blackness, oxidation resistance, uniformity of the fired film and gloss. .

Embodiments of the present invention will be described below. The composite black oxide particles of the present invention are composed of oxides of cobalt, copper, and manganese, the molar ratio of copper / cobalt is 0.1 to 0.5, and the molar ratio of manganese / cobalt is the molar ratio. 0.2 to 1.0, and the crystal structure is spinel type or reverse spinel type.

  In examining the composite black oxide particles of the present invention, according to the present inventors producing composite black oxide particles of various systems (compositions), many of them exhibit a plate-like or irregular shape. We know that things can be obtained. For example, plate-like particles can be easily obtained in Co-Mn, Co-Cu, Co-Mn-Fe, etc., and in Mn-Cu, Mn-Cu-Ni, Co-Fe-Cr, etc. Is easy to obtain irregularly shaped particles. When the shape of the particles is plate-like, the shape is somewhat uniform, but the dispersibility when made into a paint is granular, especially compared to Co-Cu-Mn-based particles exhibiting a spherical or pseudo-spherical shape, It was much inferior. In addition, it has been found that the particles having an irregular shape are inferior in the surface smoothness of the coating film when the coating is formed, as well as the dispersibility when the coating is formed. .

  Therefore, the present inventors first proceeded with studies on the shape of the composite black oxide particles that are granular, particularly spherical or pseudo-spherical, and this has been achieved in the Cu—Fe—Mn system and the Co—Cu—Mn system. I found out. However, in the Cu-Fe-Mn system, not only the dispersibility when made into a paint and the surface smoothness of the paint film when the paint is made into a coating film are excellent, but also the blackness is excellent. It is inferior in terms of properties and discoloration or fading due to oxidation.

  For this reason, it has been found that a Co—Cu—Mn-based material is preferable. However, even this composition does not satisfy all the problems required by the present invention. Here, the present inventors paid attention to the quantity ratio of these components.

First, it is important that the copper / cobalt molar ratio in the present invention is 0.1 to 0.5. When this molar ratio is less than 0.1, the resulting particles are easily coarsened and have poor colorability when formed into a paint. When this molar ratio exceeds 0.5, amorphous particles are likely to be generated, and the dispersibility and blackness when formed into a paint are inferior.

In the present invention, it is important that the manganese / cobalt molar ratio is 0.2 to 1.0. When this molar ratio is less than 0.2, the resulting particles are likely to be indeterminate such as a plate shape, the dispersibility when formed into a paint is poor, and the colorability of the coating film is also poor. In addition, even when the molar ratio exceeds 1.0, the obtained particles tend to be indeterminate such as a plate shape. Moreover, it tends to be finer and the redness of the particles becomes stronger.

  The composite black oxide particles of the present invention preferably have an average particle size of 0.05 to 0.15 μm. Such fine composite black oxide particles are excellent in the surface smoothness of the coating film when made into a paint, and the glossiness of the coating film becomes high.

  The composite black oxide particles of the present invention preferably have an oil absorption of 40 ml / 100 g or less. When this oil absorption exceeds 40 ml / 100 g, there are many agglomerated particles due to the irregular shape of the particles, resulting in poor dispersibility when formed into a paint.

  The composite black oxide particles of the present invention preferably have a BET specific surface area of 10 to 40 m <2> / g. Here, when the specific surface area by BET is less than 10 m 2 / g, the particles themselves are too large, and there is a possibility that the coloring property when formed into a paint may be poor. Not only is the surface smoothness of the coating film inferior, but the particles are too fine and the blackness may decrease.

  Further, the composite black oxide particles of the present invention have a variation coefficient of 40% or less obtained by (standard deviation of ferret diameter by SEM photograph) / (average particle diameter of ferret diameter by SEM photograph) × 100 (%). It is preferable. When this coefficient of variation exceeds 40%, the particle size distribution of the particles is too wide, and there are too many aggregated particles or too many coarse particles, resulting in poor dispersibility and smoothness of the coating film. .

  Further, the composite black oxide particles of the present invention have an L value of 20 or less, an a value of 0.1 or less, and a b value of 0 in a color difference meter according to JIS K5101-1991. .1 or less is preferable. When these numerical values do not satisfy the above conditions, the blackness is low, the hue is strong reddish or yellowish, which is a problem as a black pigment.

  In addition, the composite black oxide particles of the present invention have a ΔE value obtained by (ΔL2 + Δa2 + Δb2) 1/2 of 0 and 0.02 for samples before and after heat treatment at 180 ° C. for 2 hours in air. It is preferable that it is 5 or less. When this ΔE exceeds 0.5, the oxidation resistance is inferior.

Further, the composite black oxide particles of the present invention have a color difference L value of 35 or less, an a value of −0.5 or less, and a b value of −3.5 or less in color strength measurement using titanium oxide. It is preferable. When these numerical values do not satisfy the above conditions, the blackness is low, the hue is strong reddish or yellowish, which is a problem as a black pigment.

  Next, a preferred method for producing the composite black oxide particles of the present invention will be described. The method for producing black composite oxide particles according to the present invention is obtained by neutralizing and mixing a metal salt mixed aqueous solution prepared using a water-soluble salt of cobalt, copper, and manganese, and an alkali hydroxide, and the resulting metal hydroxide The product slurry is maintained at a pH of 10 to 13 and oxidized at a temperature of more than 40 ° C. and 60 ° C. or less, and the resulting precursor slurry is aged by raising the temperature to a range of 80 to 150 ° C. The heat treatment is performed at 400 to 700 ° C. for over 1 hour and for 3 hours or less.

  In the present invention, the composition ratio of cobalt, copper, and manganese is important when preparing a mixed aqueous solution using water-soluble salts of cobalt, copper, and manganese. In order to dissolve the metal salt used in the aqueous solution, the temperature of the aqueous solution is preferably 30 to 60 ° C. When the temperature is less than 30 ° C., there is a high possibility that an undissolved metal salt remains in the aqueous solution, and when mixed with an alkali hydroxide to form a composite hydroxide, a hydroxide with a non-uniform composition is formed. There is a risk of forming. Moreover, when it exceeds 60 degreeC, the magnitude | size of a nucleus tends to become non-uniform | heterogenous and it is estimated that the size of the composite oxide particle finally obtained also varies.

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

  An aqueous solution composed of water-soluble salts of cobalt, copper and manganese thus obtained and an alkali hydroxide are mixed to produce a hydroxide slurry of a mixture of cobalt, copper and manganese.

  The alkali hydroxide used for this neutralization is preferably a caustic alkali such as sodium hydroxide or potassium hydroxide. Moreover, about the neutralization mixing, any mixing mode may be used, but it is preferable to add alkali hydroxide to the water-soluble salt aqueous solution of cobalt, copper, and manganese, and if the addition is performed during 60 to 120 minutes, A hydroxide core particle having a uniform composition is obtained. If the addition time is shorter than 60 minutes, a non-uniform composition of hydroxide is formed or amorphous particles are likely to be generated, and if it exceeds 120 minutes, a uniform composition of hydroxide is formed. The growth of nuclei also proceeds, and irregularly shaped particles tend to be generated.

  The obtained hydroxide slurry is adjusted in a pH range of 10 to 13, and an appropriate oxidizing agent (hydrogen peroxide or the like) is added and an oxygen-containing gas, preferably air is blown into the black composite oxide particles in the slurry. Is generated. The reaction temperature at this time is preferably more than 40 ° C. and 60 ° C. or less. If the temperature is 40 ° C. or lower, the particles may be atomized and the blackness may be lowered. When the temperature exceeds 60 ° C., irregularly shaped particles are likely to occur frequently.

  The oxidation reaction is continued until the oxidation-reduction potential in the slurry reaches equilibrium, and the temperature of the slurry thus obtained is raised to 80 to 150 ° C. After the temperature rise, the black composite oxide particles in the slurry are aged by stirring at 80 to 100 ° C. for 1 to 6 hours or by using an autoclave or the like at 100 to 150 ° C. This aging is important for causing the reaction to proceed to form granular particles. When the processing temperature at this time is less than 80 ° C. (100 ° C. when using an autoclave or the like), the reaction does not proceed so easily. Particles cannot be formed, and amorphous particles are likely to be generated. When the temperature exceeds 100 ° C. (150 ° C. when using an autoclave or the like), the particle size distribution of the particles obtained due to the high reaction rate becomes wide, which is not preferable.

  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. Since the black composite iron oxide particles after the heat treatment may be partially aggregated, a conventional crushing treatment may be added.

  If the temperature during the heat treatment is less than 400 ° C., the form of the oxide is not stable, and the stability of various properties may be lacking. Moreover, when it exceeds 700 degreeC, there exists a possibility that blackness and a hue may become bad by an excessive heat load. Note that the atmosphere during the heat treatment may be in the air or in an inert gas atmosphere.

  If the composite black oxide particles of the present invention are used as a black pigment, and the black matrix, plasma display, or plasma address liquid crystal obtained by using the black pigment, the blackness, oxidation resistance, fired coating Excellent uniformity and gloss.

    Hereinafter, the present invention will be specifically described with reference to examples and the like.

[Example 1]
830 g of cobalt sulfate heptahydrate, 224 g of copper sulfate pentahydrate, and 324 g of manganese sulfate pentahydrate are poured into 6 liters of water at a temperature of 45 ° C. and dissolved by stirring. Next, 1 mol / L aqueous solution of caustic soda is added to this mixed aqueous solution. 7.1 liter was added over about 90 minutes, and the pH of the resulting hydroxide slurry was adjusted to 12. The liquid temperature after completion of the addition was 50 ° C. 30 minutes after the adjustment was completed, air was blown in at a rate of 3 liters / minute for about 2 hours while maintaining the liquid temperature at 50 ° C. Thereafter, stirring of the reaction solution was continued, the temperature was raised to 85 ° C. in about 60 minutes, and then held for 1 hour. After maintaining for 1 hour, the produced composite iron oxide particle slurry was filtered and washed, and the washed cake was dried at 80 ° C. for 10 hours. The dried product was pulverized and calcined in the atmosphere at 600 ° C. for 2 hours to obtain composite iron oxide particles having a particle size of 0.07 μm and BET of 24 m 2 / g.

<Evaluation method>
(A) Co, Cu, and Mn contents: Samples were dissolved and measured by ICP. (B) Average particle diameter: A 100,000 times photograph was taken with a SEM (scanning electron microscope), and the ferret diameter of 200 particles was measured. (C) Specific surface area: Measured with a 2200 type BET meter manufactured by Shimadzu-Micromeritics. (D) Oil absorption amount: Measured according to JIS K 5101. (E) Blackness, hue; The blackness of the powder was measured according to JIS K5101-1991. Add castor oil 1.4 cm ³ to 2.0 g of sample and knead with Hoover type Mahler. After adding 7.5 g of lacquer to 2.0 g of this kneaded sample and further kneading, this was applied onto a mirror-coated paper using a 4 mil applicator, dried, and then a color difference meter (Tokyo Denshoku Color Analyzer TC- 1800 type), blackness (L value) and hue (a value, b value) were measured. (F) Coloring power (dispersibility when made into paint): Add castor oil 1.3 cm ³ to 0.5 g of magnetite particles and 1.5 g of titanium oxide (R800 manufactured by Ishihara Sangyo Co., Ltd.), and knead with a Hoover type Mahler. After adding 4.5 g of lacquer to 2.0 g of the kneaded sample and further kneading, this is applied onto a mirror-coated paper using a 4 mil applicator, dried, and then a color difference meter (color analyzer manufactured by Tokyo Denshoku Co., Ltd.). TC-1800 type). (G) Oxidation resistance test: Put a sample in a watch glass, and dry it at 180 ° C. for 2 hours in a ventilated dryer (Oven PH-201 made by Tabai Espec). (E), (f) In the same manner, blackness, hue, and coloring power were measured. (H) Specular reflectance (glossiness associated with surface smoothness of coating film); 60 g of a solution obtained by dissolving styrene acrylic resin (TB-1000F) in (resin: toluene = 1: 2), sample after heat treatment 10 g of glass beads having a diameter of 1 mm and 90 g were placed in a bottle having an internal volume of 140 ml, capped, and then mixed for 30 minutes with a paint shaker (manufactured by Toyo Seiki Co., Ltd.). This was applied onto a glass plate using a 4 mil applicator, dried, and then measured for blackness with a color difference meter and with a reflectance of 60 degrees with an uneven GLOSS METER (GM-3M).

[Examples 2 and 3, Comparative Examples 1 to 5]
As shown in Table 1, composite oxide particles were obtained in the same manner as in Example 1 except that each production condition was changed. Various characteristics of the obtained composite oxide particles were evaluated in the same manner as in Example 1. The results are shown in Table 2.

  As is clear from Table 2, the black composite oxide particles of the examples are excellent in blackness, hue, oxidation resistance, dispersibility during coating, and surface smoothness when coating the coating.

  Compared to this, the composite oxide particles of Comparative Example 1 are irregularly shaped particles due to the large ratio of copper / cobalt and manganese / cobalt, and have excellent tinting power, but the blackness, hue, and paint are coated. The surface smoothness is inferior.

  In the oxide particles of Comparative Example 2, copper and manganese were not added. Blackness and hue decreased, and coloring power also decreased. Since the shape is plate-like, the surface smoothness when the paint is made into a coating film is lowered.

  In Comparative Example 3, the composite oxide particles composed of chromium, copper, and manganese are inferior in blackness, coloring power, and surface smoothness when formed into a paint.

  Although it is complex oxide particle which consists of a cobalt and copper composition of the comparative example 4, it is inferior to blackness, a hue, coloring power, and the surface smoothness when it makes it a coating material.

The composite oxide particles composed of the cobalt and manganese compositions of Comparative Example 5 are inferior in blackness, hue, coloring power, and surface smoothness when formed into a paint.

Claims (7)

  It is made of an oxide of cobalt, copper, and manganese, and has a copper / cobalt molar ratio of 0.1 to 0.5 and a manganese / cobalt molar ratio of 0.2 to 1.0. Spinel type or reverse spinel type composite black oxide particles. 2. The composite black oxidation according to claim 1, wherein the primary average particle size is 0.05 to 0.15 μm, and the coefficient of variation CV value of the following formula (1) in the particle size distribution by SEM observation is 40% or less. Particle.
CV value (%) = (standard deviation of particle diameter by SEM observation (μm)) / (number average particle diameter by SEM observation (μm)) × 100 (1) The composite black oxide particles according to claim 1 or 2, wherein the BET has a specific surface area of 10 to 40 m ² / g.   The composite black oxide particles according to claim 1, wherein the oil absorption is 40 ml / 100 g or less.   The black coating material containing the composite black oxide particle in any one of Claims 1-4.   A black matrix formed by the black paint according to claim 5. A metal salt mixed aqueous solution prepared using a water-soluble salt of cobalt, copper and manganese and an alkali hydroxide are neutralized and mixed in 60 to 120 minutes, and the obtained metal hydroxide slurry is adjusted to pH 10 to 13 Maintain and oxidize at a temperature above 40 ° C. and below 60 ° C., age the resulting precursor at 80-150 ° C., and after solid-liquid separation, temperature 400-700 ° C. above 1 hour, below 3 hours a method of manufacturing a double if black oxide particles you heat treatment,
Cobalt, copper, and manganese so that the molar ratio of copper / cobalt in the composite black oxide particles is 0.1 to 0.5 and the molar ratio of manganese / cobalt is 0.2 to 1.0. A method for producing composite black oxide particles, wherein the water-soluble salt is used .