JP3633710B2 - Alumina titanium-based pigment and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an alumina titanium pigment having an interference color, improved gloss and improved coloring power, and a method for producing the same.
[0002]
[Prior art]
Conventionally, as a pigment having an interference color, a natural fish scale foil made of guanine, or a mica titanium pigment obtained by coating titania with mica as a substrate particle is used. Natural fish scale foil has excellent pearly luster and has advantages such as being harmless to the human body, but it is expensive and has a limited supply amount. It also has a strong cohesion due to drying and is difficult to redisperse. There are problems such as. Mica titanium pigment is a pigment having a very excellent artificial interference color, but quality control is difficult because mica, which is a substrate particle, is a natural mineral. The performance of this pigment depends on the particle diameter and thickness of the substrate particles. However, the technology for cleaving the particles is immature, and it is difficult to produce pigments having various textures.
[0003]
However, mica titanium pigments are widely used as pigments for cosmetics, paints, plastics and the like because they have pearl luster and various interference colors. As the production method, an aqueous solution of an inorganic salt of titanium (for example, titanyl sulfate) is generally hydrolyzed in the presence of mica to precipitate hydrated titanium oxide on the mica surface, followed by calcination. The mica used is generally muscovite mica. In addition, mica is pre-wet pulverized, classified and used with a uniform particle size.
[0004]
[Problems to be solved by the invention]
Natural interference pigments made of fish scale foil have problems such as high price, aggregation during drying, and supply system. The mica titanium pigment exhibits various interference colors depending on the thickness of the titania coating layer on the mica particles. However, natural mica contains iron, and there are problems such as color dullness caused by this, and difficulty in controlling shape factors such as particle shape and aspect ratio of mica particles. Also, the mica particles used in such pigments are disadvantageous in that they are highly wet-pulverized and classified powders and cannot be stored in a dry state. In the case of mica, the melting point is about 1000 ° C. and the heat resistance is inferior to alumina. Furthermore, since it is a natural mineral, it contains components such as iron, and the iron component develops color by the calcination step after the hydrated titanium oxide coating, and color dullness is likely to occur.
[0005]
The present invention is intended to solve the above problems in the prior art.
[0006]
[Means for Solving the Problems]
The present invention is an alumina titanium pigment having an interference color, characterized in that a plate-like particle made of α-alumina is coated with a titania layer having a thickness of 10 to 500 nm .
[0007]
The present invention has led to the development of a pigment having an interference color with less dull color having improved gloss and improved coloring power by coating the surface of the plate-like particle composed of α-alumina with titania. .
[0008]
The plate-like particles made of α-alumina used in the present invention are obtained by the production methods described in JP-A-6-316413 and Japanese Patent Application No. 7-237882 (both applications related to the applicant's application, etc.). Α-alumina plate-like particles may be used. That is, it can be obtained by hydrothermal synthesis by adding NaOH, Na ₂ SiO ₃ , phosphoric acid or the like as a crystallization inhibitor to aluminum hydroxide or alumina hydrate. The α-alumina plate-like particles have excellent surface smoothness, and the shape of the α-alumina plate-like particles can be changed by changing the synthesis conditions, thereby enabling control of glitter feeling. Various colors can be produced by changing the thickness of the titania coating layer. This made it possible to create pigments showing various color sensations.
[0009]
Since α-alumina is used for the substrate particles of the interference pigment, cleavage of the substrate particles after hydrated titanium oxide coating as seen in natural mica does not occur, and there are very few irregularities around the crystal compared to natural mica. The interference color is very vivid because there is little irregular reflection of light at this site.
[0010]
The α-alumina plate-like particles in the present invention preferably have a particle size of 0.5 to 50 μm and an aspect ratio of 10 to 50. More preferable ranges of the particle diameter of the α-alumina plate-like particles include 0.5 to 15 μm and 20 to 30 μm. In the case of 0.5 to 15 μm, the luminance can be kept low. And it can be light pearly. In the case of 20 to 30 μm, the luminance can be increased, and a glittering pearl tone can be obtained. By changing the glitter feeling in this way, it can be properly used depending on the application. The thickness of the titania layer is preferably 10 to 500 nm. By increasing the thickness of the titania layer, the hue changes, but by increasing the thickness, the original color is restored and the hue changes. That is, there are a primary change in hue and a higher order change depending on the thickness of the titania layer.
[0011]
In the present invention, α-alumina plate-like particles are dispersed in pure water, urea and a water-soluble titanium salt (for example, titanium sulfate) are mixed and heated to uniformly form hydrated titanium oxide on the surface of the α-alumina plate-like particles. precipitated coated, then the alumina substrate by 600 to 1000 ° C. calcined, uniformly thick alumina titanium-based pigment having an interference color, characterized in that to coat the titania layer is 500nm from 10 manufacturing method It is.
[0012]
An amount of the water-soluble titanium salt necessary for obtaining an interference color is 0.4 × 10 ³ mol to 16 × 10 ³ mol, more preferably 1.2 × 10 ³ per 1 m ² of α-alumina plate-like particles. Add 12 x 10 ^ ³ mol from mol. If it is less than 0.4 × 10 ³ mol, the substrate particles cannot be completely coated with titania, and if it exceeds 16 × 10 ³ mol, the coating layer after the hydrated titanium oxide coating is cracked. is there. Further, 0.02 mol to 0.2 mol, preferably 0.06 mol to 0.12 mol, of urea is added per 1 m ² of α-alumina plate-like particles. If the amount is less than 0.02 mol, the particles are agglomerated at the time of coating, and if the amount exceeds 0.2 mol, the titania particles are difficult to adhere on the α-alumina plate-like particles.
[0013]
This is well dispersed in pure water, and then rapidly heated to 80 to 90 ° C. and maintained at that temperature for 2.5 to 5 hours. The titanium salt is hydrolyzed with ammonia generated by the thermal hydrolysis of urea. Then, hydrated titanium oxide is deposited on the surface of the α-alumina plate-like particles. In this case, if the temperature is less than 80 ° C., the reaction rate becomes very slow, which is inconvenient. If it exceeds 90 ° C., it is inconvenient in that the hydrated titanium oxide hardly adheres to the α-alumina particles. The α-alumina plate-like particles coated with hydrated titanium oxide are calcined at 600 to 1000 ° C. to obtain hydrated titanium oxide as titania to obtain an alumina titanium pigment. If the calcination temperature is less than 600 ° C., the titania crystal structure is not taken, and if it exceeds 1000 ° C., the titania particles grow and interference is less likely to occur.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described by way of examples.
[0015]
【Example】
Examples 1 to 3
Particle size 10 μm, aspect ratio 20 or particle size 6 μm, aspect ratio 30 or particle size 4 μm, aspect ratio 30 α-alumina plate particles 10 m ² and ion-exchanged water 200 ml, urea 0.08 mol / m ² , titanium sulfate Are mixed in a glass container of 1.4 × 10 ³ mol / m ² , 2.1 × 10 ³ mol / m ² and 2.8 × 10 ³ mol / m ² , respectively, and heated to 90 ° C. And kept at this temperature until the end of the reaction. Thereafter, washing was performed with pure water until there were almost no miscellaneous ions, followed by drying and calcination at 700 ° C. to obtain a pigment having a pure white appearance color. By applying 15 parts of the pigment and 100 parts of clear lacquer and applying this pigment to the concealment rate test paper, a coated surface having a pearly luster can be obtained. These exhibit vivid color tones of yellow, purple, and green (secondary interference colors) at each particle size, but the brightness is not so strong.
[0016]
Examples 4 to 6
Particle diameter 10 μm, aspect ratio 20 or particle diameter 6 μm, aspect ratio 30 or particle diameter 4 μm, aspect ratio 30 α-alumina plate particles 2 m ² and ion-exchanged water 200 ml, urea 0.08 mol / m ² , titanium sulfate Are mixed in a glass container of 1.4 × 10 ￣ ³ mol / m ² , 2.1 × 10 ^{３ 3} mol / m ² and 2.8 × 10 ￣ ³ mol / m ² , respectively, and heated to 80 ° C. And kept at this temperature until the end of the reaction. Thereafter, washing was performed with pure water until there were almost no miscellaneous ions, followed by drying and calcination at 700 ° C. to obtain a pigment having a pure white appearance color. 15 parts of this pigment and 100 parts of clear lacquer were mixed and applied to a concealment rate test paper to obtain a coated surface having a pearly luster. These show vivid colors of yellow, purple and green at each particle size, but the glitter is not so strong.
[0017]
Example 7
Α-alumina plate-like particles 10 m ² having a particle size of 30 μm and an aspect ratio of 20, 200 ml of ion-exchanged water, urea 0.08 mol / m ² , and titanium sulfate 1.4 × 10 ³ mol / m ² , 2.1 ×, respectively. The mixture was mixed in a 10 ³ mol / m ² , 2.8 × 10 ³ mol / m ² glass container and heated to 90 ° C. and held at this temperature until the end of the reaction. Thereafter, washing was performed with pure water until there was almost no miscellaneous ions, dried, and calcined at 700 ° C. to obtain a pigment having a pure white appearance color. This pigment can be mixed with 15 parts of pigment and 100 parts of clear lacquer and applied to a concealment rate test paper to obtain a coated surface having pearly luster. These show vivid colors of yellow, purple and green, respectively, and have a very strong glitter.
[0018]
Examples 8 to 10
Particle size 10 μm, aspect ratio 20 or particle size 6 μm, aspect ratio 30 or particle size 4 μm, aspect ratio 30 α-alumina plate particles 10 m ² and ion-exchanged water 200 ml, urea 0.06 mol / m ² , titanium sulfate Are mixed in a glass container of 0.4 × 10 ³ mol / m ² , 0.5 × 10 ³ mol / m ² and 0.7 × 10 ³ mol / m ² , respectively, and heated to 90 ° C. And kept at this temperature until the end of the reaction. Thereafter, washing was performed with pure water until there were almost no miscellaneous ions, dried, and calcined at 700 ° C. to obtain a pigment having a pure white appearance color. This pigment can be mixed with 15 parts of pigment and 100 parts of clear lacquer and applied to a concealment rate test paper to obtain a coated surface having pearly luster. These exhibit vivid color tones of yellow, purple, and green (primary interference colors) at each particle size.
[0019]
【The invention's effect】
The alumina titanium pigment of the present invention does not cause color dullness unlike a pigment having a conventional interference color, and can change the glitter by changing the particle diameter, and the thickness of the titania layer Various color sensations are shown by changing The α-alumina particles used as the substrate do not contain a colored substance, so that an interference pigment having a pure white appearance color can be obtained, and the surface is rich in smoothness and has very little irregularities around the particles. Color development is brighter than other interference pigments. Further, since it has high hardness and excellent chemical stability, it is excellent in terms of high durability as a paint used outdoors. Further, according to the production method of the present invention, a vivid color tone and pearl luster can be adjusted, and an alumina titanium pigment excellent in usability without color dullness can be obtained.

Claims (5)

An alumina titanium pigment having an interference color, wherein a plate-like particle made of α-alumina is coated with a titania layer having a thickness of 10 to 500 nm . The alumina titanium pigment having an interference color according to claim 1, wherein the α-alumina plate-like particles have a shape with a particle size of 0.5 to 50 µm and an aspect ratio of 10 to 50. α-alumina plate particles, water-soluble titanium salt and urea are mixed in an aqueous system and heated to uniformly precipitate and coat hydrated titanium oxide on the surface of α-alumina plate particles, and then calcined at 600 to 1000 ° C. alumina substrate, uniform thickness of the alumina titanium-based pigment having an interference color, characterized in that to coat the titania layer is 500nm from 10 manufacturing process by. 4. The interference color according to claim 3, which requires a titanium amount of 0.4 × 10 ⁻³ mol to 16 × 10 ⁻³ mol and a urea amount of 0.02 mol to 0.2 mol per surface area (m ² ) of the alumina to be coated. A method for producing an alumina titanium pigment. The method for producing an alumina titanium pigment having an interference color according to claim 3 or 4, wherein the liquid temperature is maintained at 80 to 90 ° C in the hydrated titanium oxide coating step.