JPH06116507A - Iridescent luster pigment - Google Patents

Abstract

PURPOSE:To obtain an iridescent luster pigment having excellent surface smoothness, brightness, color tone and durability and useful for coating material, etc., by coating a specific flaky substrate with titania, etc. CONSTITUTION:The pigment is produced by coating a flaky substrate (e.g. glass containing >=80wt.% of silica) produced from a hydrolyzable and polycondensable organometallic compound such as silicon tetraethoxide with titania, zirconia or their mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pearlescent pigment, and more particularly to a pearlescent pigment having a flake substrate coated with a metal oxide.

[0002]

2. Description of the Related Art At present, pearlescent pigments having a semi-transparent layer of titania formed on mica flakes are widely used as fillers for pigments for various paints and cosmetics such as cosmetic creams.

As a method of coating titania on the mica flakes, a method of hydrolyzing a sulfuric acid acid titanium oxysulfate solution at a boiling temperature (for example, Japanese Examined Patent Publication No. 43-25644),
Hydrolysis Method of Titanium Tetrachloride (For example, Japanese Patent Publication No. 49-38)
No. 24) is generally known.

In these methods, a titania hydrate is coated and then heat-treated at 700 to 1000 ° C. to form a stable and highly bright titania coating layer.

[0005] As a mica, usually muscovite mica (muscovit
e mica) is used. Although such mica has cleavability, the surface of the mica flakes is not completely cleaved, the thickness is not uniform even within one mica flake, and the surface thereof has step-like irregularities. This uneven step is normally 0.
It is larger than 05 μm and smaller than 1 μm.

[0006]

The step difference on the surface of the mica flakes is a factor that inhibits multiple reflection interference in the titania layer in the pigment after the formation of the titania layer, and in particular, the angle to the mica flakes is made small. It had a drawback that the color was not deep when viewed from above.

On the other hand, when commercially available flake-shaped glass is used in place of the mica flakes, there is no step on the surface and the smoothness is excellent. However, since its glass composition is soda lime silicate glass, there is a problem in heat resistance. That is, the flake-shaped glass cannot withstand the step of heat treatment at 700 to 1000 ° C. after forming the titania layer, and the heat treatment temperature must be suppressed to 600 ° C. or lower. With such a low temperature heat treatment, since the crystal structure of the titania layer is an anatase structure, it was not possible to obtain a pearlescent pigment having high luster and excellent durability.

In view of the above-mentioned prior art, the present invention provides a pearlescent pigment having a vivid and beautiful color tone which has never been produced.

[0009]

That is, the present invention provides a pigment in which a flaky substrate is coated with titania or zirconia or a mixture thereof, wherein the flake substrate is an organometallic compound capable of hydrolysis and polycondensation. A pearlescent pigment characterized by using the one obtained as a starting material.

In the present invention, the flake-shaped transparent substrate is
The method already proposed by the inventors (JP-A-3-285838)
According to 5), it can be produced from a solution containing an organometallic compound capable of being hydrolyzed and polycondensed.

That is, a solution containing an organometallic compound capable of being hydrolyzed and polycondensed is applied onto a substrate, dried to form a gel-like film, and then the gel is removed from the substrate to which the gel-like film is attached. The flaky glass is manufactured by peeling the flaky film and then sintering it.

The hydrolyzable / polycondensable organometallic compound used as a raw material in the present invention may be basically any compound as long as it can be hydrolyzed and dehydrated and condensed.
Metal alkoxides having alkoxy groups are preferred.
More specifically, methoxides such as silicon, titanium, aluminum, zirconium, phosphorus and boron, ethoxides, propoxides, butoxides and the like are used alone or as a mixture. Therefore, the composition of the flake glass obtained by the present invention, for example, flake glass of any composition, such as pure silica, silica-titania, silica-zirconia, silicate oxide containing other components, etc. can be used. Can withstand the temperature of coating and heat-treating Titania, Zirconia, etc., specifically, the softening point (temperature at which viscosity coefficient is 4.5 × 10 7th power POISE) is 1100.
It is preferable that the content of silica is 80% or more by weight, since the low-refractive-index material for the flake-like substrate is more likely to obtain pearl luster. Generally, silica glass is used.

The solvent of the raw material solution containing the above-mentioned organometallic compound may be basically any solvent as long as it substantially dissolves the above-mentioned organometallic compound, but methanol, ethanol and propanol can be used.
Most preferred are alcohols such as alcohol and butanol. The amount of this solvent used is 0.1 to 0.995, preferably 0.2 to 0.995, in volume ratio with respect to the total amount of the organometallic compound and the solvent.
9, more preferably 0.3 to 0.85.

Moisture is required for the hydrolysis of the above-mentioned raw material organometallic compound. It may be neutral, acidic or basic, but in order to accelerate hydrolysis, hydrochloric acid, nitric acid,
It is preferable to use water acidified with sulfuric acid or the like. The amount used is 1 mol to 100 mol of water with respect to 1 mol of the organometallic compound.
A molar range is preferred. The acid is used in a molar ratio of 0.01 to 2, preferably 0.0
It is 5 to 1.5.

In addition, in order to change the characteristics of the raw material solution, for example, to adjust the thickness of the solution applied to the substrate, an organic thickener or the like may be added to the solution. However, if the added amount is large, it may remain as a carbide on the thin film due to the heating in the final stage, so the amount should be 10% by weight or less.

In the present invention, the substrate to which the solution containing the hydrolyzable / polycondensable organometallic compound is to be applied is made of a material such as stainless steel, metal such as gold and silver, glass or plastic and has a smooth surface. To use. The smoothness is preferably such that the surface irregularities are less than 0.05 μm. A liquid containing the organometallic compound is applied to such a substrate to form a thin liquid film having a thickness of 0.06 to 50 μm. When this film is dried, it contracts as a gel film, but the substrate does not contract, so cracks occur in the film. The flaky substrate is manufactured by peeling the gel film from the substrate and then sintering it.

Further, the surface smoothness of the flake-like substrate produced by this method becomes very good by improving the smoothness of the substrate to which the above-mentioned solution is applied, and the step difference observed in the mica flakes is obtained. Absent.

Regarding the size of the flaky substrate used, the thickness is usually 0.05 μm to 5 μm. 5μ
If it is thicker than m, the difference in the drying speed between the film portion on the free surface and the film portion near the base material becomes too large, and the resulting flaky base material will have peeling between films in the horizontal direction on the base material. . When such peeling between films occurs, the distribution of the film thickness of the obtained flake-like substrate becomes wide and the quality as a product deteriorates. On the other hand, when the thickness is less than 0.05 μm, the adhesion between the substrate and the film becomes too large, and the film does not peel off from the substrate, and the flakes are not formed. The diameter of the flake-like substrate produced by the present invention is usually 10 μm to several mm, and its aspect ratio is at least 5, preferably at least 10.

The flaky substrate thus obtained can be coated with titania or zirconia by a known method to easily produce a pearlescent pigment having a bright reflection interference color. By controlling the thickness of the titania and zirconia to be coated in the range of 50 to 200 nm, pearlescent luster such as silver, golden, red, magenta, blue and green can be obtained.

One of the known titania coating methods described above is as follows. A flaky substrate, for example, flaky silica glass, is dispersed in water, an aqueous titanium oxysulfate solution and sulfuric acid are slowly added thereto, and this is heated to coat the surface of the flaky substrate with a titania hydrate having a predetermined thickness. By heating this at about 1000 ° C., a titania layer is formed and exhibits a pearlescent reflection interference color.

[0021]

EXAMPLES Examples will be shown below.

Example 1 Commercially available silicon tetraethoxide, ethanol, water,
The mixture was mixed at a volume ratio of 1: 2: 1 and stirred at room temperature for about 24 hours. The surface is polished, 20 cm x 20 cm
A stainless steel plate having a thickness of 1 mm was prepared as a base material. The solution prepared above was formed into a film on this substrate by dip coating and left in the atmosphere at 20 ° C. and 60% RH for 5 minutes. Then, this was put in an oven at 120 ° C. and dried for 2 minutes, and the gel film separated from the substrate was collected with a nylon brush. Collect the collected flaky silica gel at 1000 ° C for 2
Heat treatment was performed for an hour to obtain flake-shaped silica glass.

When the surface of the flake silica glass was observed with an electron microscope, no surface step was observed and the surface was smooth.

15 g of this flake-shaped silica glass was added to 10
It was dispersed in 0 ml of water and kept at 80 ° C. Where 12
titanium oxysulfate aqueous solution corresponding to 1 g of titanium dioxide 1
00 g and 50 g of 50% sulfuric acid were slowly added. This was heated and boiled for about one and a half hours. While reacting, one drop of the slurry was taken and placed on a black background, and the interference color due to the titania hydrate layer was observed. When this color turned reddish orange, the boiling was stopped. The slurry was filtered, washed with water to remove sulfuric acid, and dried.

The resulting titania hydrate coated flakes were
Heat treatment was performed at 1000 ° C. for 1 hour to obtain a golden pearlescent pigment composed of titania-coated flake silica glass. Its dimensions were a thickness of about 0.7 μm and an average particle size of about 60 μm. The thickness of the titania layer was about 85 nm.
This pearlescent pigment was dispersed in an acrylic resin in an amount of about 5% by weight and applied on a metal substrate coated with a black paint. The interference color of this pearlescent pigment was a very deep golden color with no fog, which was superior to conventional pearlescent pigments made from mica.

Comparative Example-1 In Example-1, instead of 15 g of the flake silica glass, muscovite powder (Japan Mica Mfg. Co., Ltd.,
Coating of titania was carried out in the same manner except that 30 g of A50) was used.

The obtained pearlescent pigment had the same golden color as that of Example-1, but was less deep than that of Example-1, and some cloudiness was observed.

When the mica flakes used were observed with an electron microscope, many uneven steps of 0.1 to 0.5 μm were recognized in one flakes.

Comparative Example-2 In Example-1, instead of 15 g of the flake-like silica glass, C glass flake (Nippon glass fiber 〓, soda lime silicate glass composition, "Fainlake RCF-1" was used.
The coating of titania hydrate was carried out in the same manner except that 40 g) was used.

When this was heat-treated at 1000 ° C.,
The flakes were softly deformed and did not retain the form of powdery pigment.

Then, heat treatment was carried out at 600 ° C. for 2 hours, the obtained pigment was dispersed in an acrylic resin by the same method and conditions as in Example-1, and coated on a black substrate. The interference color was orange, which was less vivid than the pigment from the mica shown in Comparative Example-1.

When the used C glass flakes were observed with an electron microscope, the surface of the flakes was smooth and no uneven step was observed.

Example-2 Aqueous solution 30 in which the pH was adjusted to 2.7 by adding urea in advance.
Zirconium sulfate corresponding to 10 g of zirconium dioxide was dissolved in 0 ml. To this, 12 g of the flake silica glass described in Example-1 was added and heated to 90 ° C,
It was kept at this temperature for about one and a half hours with good stirring. Then, the slurry was filtered, washed with water and dried. this,
It heat-processed at 800 degreeC for 1 hour. The thickness of the zirconia layer was about 80 nm. It was dispersed in an acrylic resin and coated on a black substrate in the same manner as in Example-1. The pigment was a bright silver color with a strong shine.

Comparative Example-3 Zirconia was coated under the same method and conditions as in Example-2 except that 30 g of muscovite powder described in Comparative Example-1 was used.

The obtained pigment was silver, but the brightness and brilliance were inferior to those of the pigment prepared in Example-2.

[0036]

INDUSTRIAL APPLICABILITY The present invention has a pearly luster that is brighter and deeper than conventional, in which a flaky substrate having excellent surface smoothness and high heat resistance is coated with fine particles of titania or zirconia alone or a mixed oxide thereof. A pigment can be provided.

[0037]

Claims (2)

[Claims] 1. A pigment in which a flaky substrate is coated with titania or zirconia or a mixture thereof,
A pearlescent pigment, wherein the flake-like substrate is obtained by using an organometallic compound capable of hydrolysis and polycondensation as a starting material. 2. The pearlescent pigment according to claim 1, wherein the flaky substrate is glass containing 80% by weight or more of silica.