JP4839043B2 - Composite oxide black particles, method for producing the same, black paint and black matrix - Google Patents

Description

  The present invention relates to a composite oxide black particle, a method for producing the same, a black paint, and a black matrix, and more specifically, a composite oxide black particle comprising a composite oxide containing molybdenum, for paint, for ink, for toner, and rubber・ Suitable for black pigments for plastics, etc., especially for black matrix coloring composition, plasma display, black electrode on front plate such as plasma address liquid crystal, composite for excellent blackness The present invention relates to black oxide particles, 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 and hiding power, and to be inexpensive. Carbon black Iron oxide pigments such as magnetite and other complex oxide pigments are used depending on the application.

  As typical examples of black pigments mainly composed of metal oxides, Patent Documents 1 to 3 can be cited, and all of the complex oxide black pigments are copper, chromium, iron, manganese, cobalt, aluminum, nickel, zinc, There is a disclosure that it is a composite oxide containing two or more metals selected from the group consisting of antimony, titanium and barium as a main metal component, more specifically. Typical compositions include Cu-Cr, Cu-Mn, Cu-Fe-Mn, Co-Cr-Fe, Co-Cr-Fe-Mn, and Co-Ni-Cr-Fe. Yes.

  Recently, in various fields using black pigments, demands for higher performance and higher quality are increasing, and black pigments are required to be atomized. There is a strong demand for black matrix coloring compositions, plasma displays, black electrodes on front plates such as plasma addressed liquid crystals, and black pigments for forming light shielding layers.

JP-A-9-124972 JP-A-9-237570 JP 2000-235114 A

However, the black pigment in the above prior art exhibits a reddish color due to light scattering when atomized. For this reason, there is a strong demand for black pigments that do not easily exhibit redness even when atomized.
Accordingly, an object of the present invention is to provide black particles in which the disadvantages of the prior art are eliminated.

  The present inventors have studied various components constituting the black pigment, and by imparting a bluish color to the pigment, a composition that can cancel the reddishness caused by light scattering due to atomization and maintain a sufficient blackness We conducted an intensive study. As a result, the present inventors have found that composite oxide black particles made of composite oxide containing molybdenum can solve the above problems, and have completed the present invention.

That is, the composite oxide black particles of the present invention comprise at least molybdenum, the content is Ri 0.3 to 30% by mass, further copper, chromium, manganese, nickel, and any one of zinc or 2 It contains seeds or more, and the average particle diameter of primary particles by SEM observation is 0.02 to 0.1 μm .

  The black composite oxide particle according to the present invention is a paint that requires a fine black pigment because it is a black pigment with a very strong bluish color and does not exhibit redness even when atomized. It is suitable as a black pigment for inks, inks, toners, rubbers and plastics. Particularly, it is suitable for forming a black matrix coloring composition, a plasma display, a black electrode of a front plate such as a plasma address liquid crystal, and a light shielding layer.

  Embodiments of the present invention will be described below.

  The composite oxide black particles of the present invention are composite oxide black particles characterized by containing at least molybdenum.

  In studying the composite oxide black particles of the present invention, according to the present inventors producing composite oxide black particles of various systems (compositions), black pigment particles are generated in various metal oxide systems. I know you will. For example, there are a Co—Mn system, a Co—Cu system, a Co—Mn—Fe system, and the like. However, these composite oxides become reddish as the particle diameter is reduced.

  As a result of intensive studies by the present inventors, the complex oxide black particles of the present invention containing molybten are very bluish black pigments, and even if they are fine particles, redness is suppressed. In short, when compared with the same particle size, redness is suppressed in the composite oxide containing molybten than in the composite oxide not containing molybten. In other words, when the particles having the same color are compared, the composite oxide black particles of the present invention can have a smaller particle size.

  In the composite oxide black particles of the present invention, it is important that the content of molybdenum is 0.3 to 30% by mass with respect to the entire particles. When the amount is less than 0.3% by mass, the effect of improving the color tone cannot be sufficiently obtained. Moreover, when the content of molybden is more than 30% by mass, molybden is not sufficiently taken into the particles and exists as an indeterminate shape, which impairs the color. Considering the balance between color improvement and particle formation, the content is preferably 1 to 15% by mass.

  Further, the complex oxide black particles of the present invention cannot constitute complex oxide black particles only with molybdenum oxide. Coexistence with oxides excellent in blackness other than molybdenum oxide is necessary. A single oxide of molybten is not only insufficient in terms of blackness, but is not preferable as an industrial product because molybten is an expensive material.

As an oxide composition other than molybdenum, one or more oxides or composite oxides of copper, chromium, manganese, nickel, and zinc are used. The oxide selected from the said group, or complex oxide is very excellent black particle | grains as it exists in patent documents 1-3. However, since these black pigments have an insufficient bluish color, many of the black pigments exhibit a reddish color when atomized. On the other hand, the black pigment of the present invention must contain molybdenum in order to improve the color.

The composite oxide black particles of the present invention have an average particle diameter of primary particles by SEM observation Ru 0.02~0.1μm der. The average particle diameter here means an average value of the ferret diameters of 200 particles obtained by taking a 100,000 times photograph with a SEM (scanning electron microscope). When the average particle size is within this range, it is preferable that there is no problem in forming a black matrix or an electrode that is required to be miniaturized, and sufficient blackness can be secured.

The composite oxide black particles of the present invention preferably have a specific surface area of 10 to 70 m ² / g by the BET method, corresponding to an average particle size of 0.02 to 0.1 μm of primary particles by SEM observation. Here, if the BET specific surface area is less than 10 m 2 / ^g, and the particle itself too large, a possibility that the coloring property when the coating material is defective is generated, if it exceeds 70m 2 / ^g, cohesion This is not preferable because it may cause a non-uniform dispersion.

  Further, the composite oxide black particles of the present invention have an L value of 21 or less, an a value of 0.2 or less, and a b value of 0.2 in a primary color coating film of a powder based on JIS K5101-1991. It is preferable that it is 2 or less. When these numerical values do not satisfy the above conditions, the blackness is low, the hue is not sufficiently suppressed in redness, and it is a defect as a black pigment.

  In addition, the composite oxide black particles of the present invention preferably have an L value of 34 or less and a b value of −4.0 or less as measured by a color difference meter in a color developing coating film evaluation using titanium oxide. When these numerical values do not satisfy the above conditions, the blackness is low due to poor dispersibility, and the hue is not preferable because the redness is not sufficiently suppressed. In addition to the above conditions, the a value is more preferably −1.0 or less.

  Moreover, the composite oxide black particles of the present invention preferably have an oil absorption of 20 to 50 ml / 100 g or less. When the oil absorption is less than 20 ml / 100 g, the compatibility with the organic solvent used in the paint is deteriorated, which is not preferable. Further, when the oil absorption exceeds 50 ml / 100 g, there are many agglomerated particles due to the irregular shape of the particles, and as a result, the dispersibility and the fluidity of the powder are inferior.

  Further, the complex oxide black particles of the present invention preferably have a specular reflectance (60 degrees) measured by a gloss meter of 65% or more, and more preferably 70% or more. When the reflectance is less than 65%, the glossiness when formed into a paint is inferior, and the smoothness of the coating film tends to be poor, which is not preferable.

  In addition, the composite oxide black particles of the present invention preferably have an aggregation degree of 35% or less. When the degree of aggregation exceeds 35%, the particles are remarkably aggregated, resulting in not only poor fluidity but also poor dispersibility in the resin.

  Next, a preferred method for producing the composite oxide black particles of the present invention will be described.

  The composite hydroxide slurry containing at least molybdenum is wet-oxidized, and the resulting oxide precursor particles are filtered, washed, dried and crushed, and then fired at 300 to 900 ° C. A dark black particle is obtained.

  A composite hydroxide slurry containing at least molybdenum can be obtained as follows. A molybdate salt and an aqueous solution containing at least one metal salt other than molybten are neutralized and mixed using an alkali hydroxide. The water-soluble molybdate salt is preferably a water-soluble salt such as sodium molybdate, ammonium molybdate, and molybdochloride. As metal salts other than molybdenum, soluble salts such as sulfates, chlorides, nitrates and carbonates of copper, chromium, manganese, nickel, and zinc are preferable. Further, as the alkali hydroxide, sodium hydroxide, potassium hydroxide, aqueous ammonia and the like generally used in industry are preferable.

  Further, the concentration of molybten and the aqueous solution of metal salt other than molybten is not particularly limited as long as it is equal to or lower than the saturated concentration, but considering the industrial productivity, the total metal concentration is 0.2 to 2.0 mol / liter. Is preferred. When the total metal concentration is 0.2 mol / liter or less, the amount that can be produced per unit slurry volume is small, which is not industrially suitable. In addition, when the slurry concentration exceeds 2 mol / liter, the viscosity of the molybdenum-containing hydroxide mixed slurry becomes too high, and a very high energy mixing device must be used for uniform mixing, resulting in high energy costs. Therefore, it is not preferable. Considering both mass production and energy cost, 0.5 to 1.5 mol / liter is more preferable.

  Further, in order to obtain a composite hydroxide slurry containing at least molybten, neutralization mixing of molybten and an aqueous metal salt solution other than molybten and alkali hydroxide may be in any mixing mode, but a more uniform composite hydroxide. In order to produce a slurry, it is more preferable to simultaneously add an aqueous solution of metal other than alkali hydroxide and molybdenum to the molybdenum-containing aqueous solution.

  Moreover, in order to obtain a composite hydroxide, hydroxide core particles having a uniform composition can be obtained by performing neutralization mixing slowly at a speed of 0.1 to 1.5 liters / minute. If the addition rate is faster than 1.5 liters / minute, a hydroxide having a non-uniform composition is formed or irregularly shaped particles are likely to be generated. The products and oxides are not much different from the products obtained within the above range, and this is not preferable in view of productivity.

  Moreover, it is preferable to adjust pH of the hydroxide slurry at the time of obtaining a hydroxide to 9-13. As an adjustment method, it is possible to adjust the addition rate of the alkali hydroxide to be used or adjust the concentration of the alkali hydroxide to be used while constantly monitoring the slurry pH during the neutralization mixing. When the slurry pH is less than 9, the resulting hydroxide tends to be unstable, and when it becomes an oxide, the particle shape tends to be indefinite, and conversely, when the pH exceeds 13, Since stability tends to be high and it tends to be difficult to form an oxide, it is not preferable. Considering the balance between the two, the pH of the hydroxide slurry when obtaining the hydroxide is more preferably 10-12.

  It is important that the thus obtained composite hydroxide containing at least molybdenum is oxidized by a wet process. As a means for wet oxidation, there are a method of blowing an oxygen-containing gas into a slurry, a method of adding an oxidizing agent such as hydrogen peroxide, and the like. Air or the like can be used as the oxygen-containing gas. The composite hydroxide becomes a precursor of the composite oxide black particles of the present invention by being oxidized. When wet oxidation is not performed, the precursor generation is insufficient, and particles with sufficient blackness and redness cannot be obtained.

  In addition, when wet oxidation is performed, a method for measuring the oxidation-reduction potential can be used as a method for grasping whether or not the action of oxidation is sufficient. Specifically, wet oxidation is continued until there is no change in the redox potential. If the wet oxidation / reduction is not sufficient, the precursor generation is insufficient, and particles with sufficient blackness and redness cannot be obtained.

  Moreover, it is preferable that the slurry temperature at the time of performing wet oxidation is 30-60 degreeC. When the slurry temperature is less than 30 ° C., the progress of the oxidation reaction is slow, and even when the slurry temperature is higher than 60 ° C., the oxidation reaction proceeds rapidly and the particle shape tends to be non-uniform.

  Further, the slurry containing the fully oxidized composite oxide precursor is preferably aged. As a condition for sufficient aging, there is a method in which the slurry is heated to 50 to 150 ° C. and stirred at the slurry temperature for 1 to 6 hours. By this aging, the particle shape and particle size distribution of the composite oxide precursor particles can be balanced. For aging at 100 ° C. or lower, heating using an electric heater or steam may be performed in the atmosphere, but when aging is performed at a temperature higher than 100 ° C., a high-pressure vessel such as an autoclave may be used. When the aging temperature is lower than 50 ° C., the produced particles may contain an irregular shape, which is not preferable. When the temperature exceeds 150 ° C., the precursor particles grow excessively, and as a result, composite oxide precursor particles having a large particle size may be generated, which is not preferable. Considering the suppression of irregular shaped particles and the balance of the particle shape, aging at 60 to 95 ° C. is more preferable. Further, when the time for aging is shorter than 1 hour, the effect of aging is not sufficiently exhibited, and even if it is performed for 6 hours or more, there is no difference in the generated particles, which is not economical and not preferable. Considering the effect and economy, it is more preferable to perform aging for 2 to 4 hours.

  Next, the obtained slurry containing the composite oxide precursor particles is filtered and washed in a conventional manner, and further dried to remove the contained water.

  Moreover, it is preferable that the moisture content of the dried composite oxide precursor particles obtained by evaporating moisture is 1% by mass or less. The moisture content is controlled by appropriately adjusting the drying temperature and drying time. The drying temperature is preferably 50 to 120 ° C. When the water content is more than 1% by mass, a large amount of water vapor is generated in the baking step described later, which is not preferable. The water content is more preferably adjusted to 0.1 to 0.6% by mass.

  Moreover, it is necessary to perform crushing operation with respect to the dried product which adjusted the moisture content to 1 mass% or less. When the crushing operation is not performed, the aggregated composite hydroxide precursor particles are supplied to a firing step described later, and problems such as further promotion of aggregation are caused by the firing. As the crushing device, a high-speed rotary hammer mill, impact mill, disk mill or the like is preferable.

  The composite oxide precursor particles thus obtained are fired at 300 to 900 ° C. This is because the complex oxide precursor particles do not change to complex oxide black particles unless firing is performed. When the firing temperature is less than 300 ° C., the shape change is not sufficient, and sufficient blackness and blueness cannot be obtained. On the other hand, when the temperature exceeds 900 ° C., the sintering of the particles proceeds, the particle diameter increases, the coloring performance is inferior, and it is not suitable as a black pigment. More preferable conditions at the firing temperature are 500 to 700 ° C.

  In addition, the firing time is preferably 1 hour to 3 hours. When the firing time is less than 1 hour, the shape change is not sufficient, and when it exceeds 3 hours, sintering of the particles may proceed, which is not preferable.

  Moreover, the atmosphere at the time of baking may be in the air, in an inert gas atmosphere, or at an oxygen concentration of 21% by volume or more.

  When the complex oxide black particles containing molybdenum obtained as described above are crushed to loosen the aggregate, the coloring performance as a black pigment is improved, which is even more preferable. As a crushing method, either a dry method or a wet method may be used. Examples of the dry crushing method include a jet mill using an air current, such as a high speed rotating hammer mill, an impact mill, a disk mill, a wheel type kneader having an action of compression, shear, and spatula. As a wet pulverization method, molybten-containing composite oxide black particles obtained by firing are cooled to at least around room temperature and suspended in water, and then a high-speed rotating homomixer, wet jet mill, and media are used. Examples of the treatment method include a wet ball mill and an attritor. In the case of wet-type crushing, it is necessary to dry again in order to remove moisture by performing filtration and washing again. In both dry and wet crushing operations, it is not preferable to add a strength operation that destroys the particles themselves. When the particles are destroyed by such an operation, the particle size distribution becomes wide, which may affect the performance as a pigment, particularly the color.

  Moreover, in order to remove the aggregated particles, a classification operation can be added as necessary. Examples of the classification operation include air classification such as a dry vibration sieve and a dry cyclone, and a wet cyclone as a wet method.

  The black paint obtained by using the composite oxide black particles of the present invention, and the black matrix, plasma display, or plasma address liquid crystal obtained by using the black paint, blackness, fluidity, and oxidation resistance. The fired film has excellent uniformity and gloss.

  Hereinafter, the present invention will be specifically described with reference to examples and the like. However, the scope of the present invention is not limited to such examples.

[Example 1]
5 liters of sodium molybdate aqueous solution 0.15 mol / liter was prepared (A liquid).
Separately from the sodium molybdate aqueous solution, 3 liters of manganese sulfate pentahydrate aqueous solution 1.1 mol / liter was prepared (Liquid B).
Furthermore, 1.2 liters of 12 mol / liter sodium hydroxide aqueous solution was prepared (C solution).
After each solution was prepared, solution A was placed in a 20 liter reaction vessel equipped with a stirrer, and solution B was continuously added thereto at a rate of 0.5 liter / minute. Then, C liquid was also added continuously and it adjusted so that pH of a mixed slurry might be set to 12. Meanwhile, the slurry temperature was maintained at 40 ° 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., and the air blowing was terminated when the oxidation-reduction potential stopped changing.
Further, the produced composite hydroxide precursor particle-containing slurry was heated to 85 ° C., and then aged for 3 hours. The composite hydroxide precursor particle-containing slurry thus aged was filtered and washed, followed by drying at 80 ° C. for 10 hours to obtain a dried composite hydroxide precursor particle having a moisture content of 0.2% by mass. .
The dried product was pulverized and fired at 600 ° C. for 2 hours in the air to obtain composite oxide particles.

  The obtained composite oxide particles were evaluated by the following methods. The evaluation results are shown in Table 1.

<Evaluation method>
(A) Metal content other than molybden and molybten Samples were dissolved and measured by ICP.
(B) Average particle diameter of primary particles by SEM observation (hereinafter referred to as SEM diameter)
A 100,000 times photograph was taken with an SEM (scanning electron microscope), and the ferret diameter of 200 particles was measured.
(C) Aggregation degree (fluidity)
The vibration time was measured at 65 sec using “Powder Tester Type PT-E” (trade name) manufactured by Hosokawa Micron. The degree of aggregation was determined from the measurement result using a predetermined calculation formula.
(D) Specific surface area Measured with a 2200 type BET meter manufactured by Shimadzu Micromeritics.
(E) Oil absorption amount It carried out based on JISK5101-1991.
(F) Primary color coating film measurement The primary color coating film measurement of powder was performed based on 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). TC-1800 type), L, a, b values were measured.
(G) Color-development coating film measurement Add castor oil 1.3cc to sample 0.5g and titanium oxide (Ishihara Sangyo R800) 1.5g, and knead with Hoover-type Mahler. After adding 4.5 g of lacquer and kneading, this was applied onto a mirror-coated paper using a 4 mil applicator, dried, and then dried with a color difference meter (color analyzer TC-1800 manufactured by Tokyo Denshoku Co., Ltd.). , A, b values were measured.
(H) Specular reflectance (Glossiness associated with surface smoothness of coating film)
60 g of a solution prepared by dissolving styrene acrylic resin (TB-1000F) in (resin: toluene = 1: 2), 10 g of the heat-treated sample, and 90 g of glass beads having a diameter of 1 mm are placed in a bottle having an inner volume of 140 ml, and the lid is closed. Then, it was mixed for 30 minutes with a paint shaker (manufactured by Toyo Seiki Co., Ltd.). This was coated on a glass plate using a 4 mil applicator, dried, and then measured for a reflectance of 60 degrees with a murakami gloss meter (GM-3M).

[Examples 2-7, Comparative Examples 1-5]
Composite oxide particles were obtained in the same manner as in Example 1 except that the metal salt aqueous solution having the composition shown in Table 1 was used.
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 molybdenum-containing composite oxide black particles of the examples were particles excellent in the blackness of the color-extracted coating film, in particular, the bluish blackness. In addition to fluidity, it was excellent in dispersibility during coating and surface smoothness when coating the coating.

  Compared to this, the composite oxide particles of Comparative Example 1 have an excessive molybdenum content, and thus cannot be taken into the composite oxide particles, and a large number of simple amorphous oxide particles are generated. . As a result, the amount of oil absorption was high, and the blackness and hue of the developed color coating film were inferior (all the developed color L, a, and b values were high). In addition, the specular reflectance was low, the dispersibility and the fluidity of the powder when formed into a paint were inferior, the cohesion was high, and the smoothness of the coating film was adversely affected.

  Since the composite oxide particles of Comparative Examples 2 to 4 are composite oxide particles containing other metal elements instead of molybdenum, the color development hue was inferior in spite of the same particle size as in the examples ( (Expand colors a and b values are both higher). Moreover, the specular reflectance and the degree of aggregation were slightly inferior, and the dispersibility when formed into a paint and the smoothness of the coating film were also adversely affected.

Since the composite oxide particles of Comparative Example 5 had a low molybdenum content, the effect of containing molybdenum was insufficient, and the hue of the color-developing coating film was inferior (both the color development a and b values were high). Moreover, the specular reflectance was low, and the dispersibility and the fluidity of the powder when in paint were inferior.

Claims (10)

Containing at least molybdenum, and its content is 0.3-30% by mass,
In addition, one or more of copper, chromium, manganese, nickel, and zinc are included,
Composite oxide black particles having an average primary particle size of 0.02 to 0.1 μm by SEM observation. A composite hydroxide slurry containing molybdenum and one or more of copper, chromium, manganese, nickel, and zinc is wet-oxidized, and the resulting oxide precursor particles are heated at 300 to 700 ° C. The composite oxide black particles according to claim 1, which are obtained by firing.   The composite oxide black particles according to claim 1, wherein the aggregation degree is 35% or less.   The composite oxide black particles according to any one of claims 1 to 3, having an L value of 34 or less and a b value of -4.0 or less in color difference measurement of a color-extracted coating film using titanium oxide.   In the primary color coating film evaluation of the powder based on JIS K5101-1991, L value by a color difference meter is 21 or less, a value is 0.2 or less, and b value is 0.2 or less. The composite oxide black particles described.   The composite oxide black particles according to any one of claims 1 to 5, wherein an oil absorption amount based on JIS K 5101-1991 is 20 to 50 ml / 100 g or less. The complex oxide black particles according to any one of claims 1 to 6, wherein a specular reflectance at 60 degrees measured by a gloss meter is 65% or more.   A black paint containing the composite oxide black particles according to claim 1.   A black matrix formed by the black paint according to claim 8. A method for producing the composite oxide black particles according to any one of claims 1 to 7,
A composite hydroxide slurry containing molybdenum and one or more of copper, chromium, manganese, nickel, and zinc is wet-oxidized, and the resulting oxide precursor particles are filtered, washed, and dried. The method for producing composite oxide black particles characterized by firing at 300 to 700 ° C. after crushing.