JPH0379673A - Production of colored mica titanium-based pigment - Google Patents

Abstract

PURPOSE:To obtain the title pigment with pearl gloss and bright color tone, also good in usability by mixing metallic titanium with titanium dioxide-coated mica followed by reduction under low-oxygen condition at a specified temperature. CONSTITUTION:The objective pigment can be obtained by mixing metallic titanium with titanium dioxide-coated mica followed by reduction under low- oxygen condition at 500-1000 (pref. 700-900) deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing colored mica titanium pigments, and particularly to a method for producing pigments that develop color by reduction with titanium.

[Prior Art] A titanium mica pigment in which a titanium dioxide layer is formed on the surface of fine flaky mica has pearlescent luster and various interference colors. For this reason, it is widely used not only in the field of cosmetics but also as a pigment for various purposes.

Vacuum deposition is another method for producing mica titanium pigments, but it involves hydrolyzing an aqueous solution of an inorganic acid salt of titanium (for example, titanyl sulfate) in the presence of mica to precipitate hydrated titanium dioxide on the mica surface. A common method is to heat the mixture after heating (see Japanese Patent Publication No. 4325644).

By the way, the produced mica titanium pigment exhibits various interference colors depending on the thickness of the titanium dioxide coating layer on the mica particle surface.

The interference color shows that the amount of titanium dioxide is 10-26% by weight of the product.
26% to 40% is gold, 40%
In the range of ~50%, the color changes from red to blue to green in the direction of increasing titanium dioxide layer, and furthermore, from 50 to 60%, higher order interference colors are obtained.

However, although these mica titanium pigments have pearlescent luster and various interference colors, the appearance color is always close to white, and no one that exhibits a bright chromatic appearance has been obtained.

Conventionally, coloring pigments such as iron oxide, navy blue, chromium oxide, carbon black, and carmine were added to the produced mica titanium pigments in order to produce various external colors.

[Problem to be solved by the invention] However, the safety, stability, light resistance, acid resistance, alkali resistance, solvent resistance, heat resistance, etc. of these colored mica titanium pigments depend on the properties of the added coloring pigment. However, there are many.

For this reason, for example, a blue mica titanium pigment to which navy blue has been added fades in an alkaline solution, and a red mica titanium pigment to which carmine has been added fades and deteriorates when exposed to light.

On the other hand, in the case of mica titanium-based pigments containing carbon black, 3.
The carcinogenicity of 4-benzpyrene has become a problem, and in the case of green mica titanium pigments containing chromium oxide, there are many safety concerns such as the oral toxicity of hexavalent chromium.

Furthermore, since the above-mentioned colored mica titanium pigment contains a colored pigment, it also has problems such as color separation in the solvent.

The present invention was made in view of the problems of the prior art, and its purpose is to have a bright color tone with pearlescent luster, stability, safety, light resistance, acid resistance, alkali resistance, solvent resistance, and heat resistance. An object of the present invention is to provide a method for producing a colored mica titanium pigment having excellent properties.

[Means for Solving the Problems] As a result of intensive research by the present inventors to achieve the above object, the present inventors have found that by reducing at least a portion of the titanium dioxide on the surface of mica particles to lower titanium oxide, the conventional method can be improved. We have completed the present invention by discovering that it is possible to obtain a mica titanium pigment that has a color tone as bright as or more vivid than that of a colored mica titanium pigment, which has a pearlescent luster, and is superior in terms of safety.

That is, the present invention is a method for producing a colored mica titanium pigment characterized by mixing metallic titanium with mica coated with titanium dioxide and reducing the mixture at 500 to 1000° C. under low oxygen conditions.

Next, the configuration of the present invention will be explained in more detail.

The mica used in the present invention may be of any type, and is generally muscovite mica (muscovLte m1ca).
However, in some cases, it is also possible to use biotite or the like.

The particle size is not particularly limited, but the particle size of commercially available mica is 1
~50 μm, and among these, particles with a small particle size and a particle shape as flat as possible are more likely to exhibit beautiful color tone and pearlescent luster when used as a colored mica titanium pigment.

Then, metallic titanium is mixed with the mica titanium pigment, and the mixture is heated to 500 to 1000°C, preferably 700°C to 90°C.
Heat and reduce at 0°C.

In the produced colored mica titanium pigment, the amount of titanium dioxide and lower titanium oxide or lower titanium oxide coating the mica can be varied over a wide range. Normal mica 100
Up to an amount of titanium dioxide of 0 to 60 parts for the heavy foot part,
Lower titanium oxide can be coated in an amount of 0.01 to 6 parts by weight.

The amount of lower titanium oxide is 0 with respect to 100i1i parts of mica.
．． If less than 0.01 parts by weight is coated, the resulting mica titanium pigment will not be colored. If the amount exceeds 60 parts by weight, the properties of the mica will be extremely poor and the particles will agglomerate strongly. This property holds true even when the amount of titanium dioxide exceeds 60 parts by weight per 100 parts by weight of mica.

[Example] Next, the present invention will be explained in more detail with reference to Examples. Note that the present invention is not limited to this. Moreover, in each example, parts represent parts by weight.

First, prior to specific examples, a method for measuring the amount of titanium dioxide and lower titanium oxide covering the surface of mica particles will be described.

2. Titanium All samples before and after titanium reduction treatment were pulverized using an agate ball mill to render mica amorphous. The intensity of the diffraction line of titanium dioxide and the diffraction line of lower order titanium oxide was determined using the powder measurement method of X-ray diffraction (α rays for Cu-) of the sample. Then, the amounts of titanium dioxide and lower titanium oxide were determined by comparing the intensity with a separately determined mixing ratio of mica and titanium dioxide and a calibration curve of diffraction intensity for which the mixing ratio of lower titanium oxide was known.

Low Feed E + 2 and > (D Amount) Since all low titanium oxide changes to titanium dioxide by firing in the atmosphere, a gravimetric analysis is performed on the sample that has been subjected to reduction treatment to quantify the amount of low titanium oxide. did.

That is, about 5 g of a sample was accurately weighed into a 20 m 1 human magnetic crucible and heat-treated at 800° C. for 4 hours in the atmosphere. After cooling, the weight increase was accurately measured, and the amount of lower titanium oxide was determined from the weight increase.

50 parts of Jikoku 0-beating mica was added to 500 parts of ion-exchanged water and thoroughly stirred to uniformly disperse it. 3,125 parts of an aqueous titanyl sulfate solution having a concentration of 40% by weight was added to the obtained dispersion, and the mixture was heated and boiled for 6 hours while stirring.

After cooling, the mixture was filtered, washed with water, and fired at 900° C. to obtain 100 parts of mica coated with titanium dioxide (titanium mica).

Next, 1.2 parts of metallic titanium was mixed with 100 parts of the obtained mica titanium, and the mixture was mixed with 10-
The mixture was heated and reduced at 800° C. for 4 hours at a vacuum level of less than Jtorr. After cooling, 101.2 parts of powder was obtained. The obtained powder was a bright blue-green powder with pearlescent appearance and interference color.

In addition, when determining the amounts of titanium dioxide and lower titanium oxide that coat mica in the blue-green mica titanium pigment that is this product, it is found that titanium dioxide is 40.5 parts by weight per 100 parts by weight of mica. It was found that titanium suboxide was 9.5 parts by weight.

Take 50 parts each of 4 types of mica titanium pearlescent pigments with interference colors, which are commercially available (manufactured by Marl Corporation in the United States), and mix the mixture with different amounts of metallic titanium using a diffusion pump. 10-”
The vacuum degree was set to below torr, and the mixture was heated and reduced at 80°C for 4 hours.

After cooling, the color and interference color of the obtained powder were observed with the naked eye, and the color tone was measured by the powder cell method using a color analyzer 607 (hue H11 part V, saturation C).

The results are shown in Table 1 below.

(Hereinafter, blank spaces) The pigment properties of the colored mica titanium pigments obtained in Examples 1 to 5 above were tested. For comparison, a colored mica titanium-based pearlescent pigment commercially available from Marl Co., Ltd.
The pigment properties of a conventional mica titanium pigment (addition of a colored pigment) were similarly tested. As the commercially available colored mica titanium-based pearlescent pigments for comparison, those corresponding to the color tones of the colored mica titanium-based pigments of Examples 1 to 5 were selected.

The correspondence is shown in the table below.

Table 2 The composition of the commercially available product is shown in Table 3 below.

Table 3 Commercially available colored mica titanium pearlescent pigment composition The test items are acid stability, alkali stability, light stability, thermal stability, and dispersion stability, and the test methods and test results are as follows.

■ Acid stability test 1.5 g of the colored mica titanium pigment, which is a product of the present invention, and 1.5 g of the commercially available colored mica titanium pearlescent pigment were each placed in a 50 ml test tube with a stopper, and 3 parts of a 2N aqueous hydrochloric acid solution was added to the test tube.
After adding 0ml and dispersing, stand it on the test placket and leave it still.
The color tone after 4 hours was observed with the naked eye. The results are shown in Table 4.

Test results in Table 4: ○: Very stable with no change in color tone △: Gradually fades and the color tone becomes pale and whitish ×: Fades and changes to white As is clear from the results in Table 4, this is a product of the present invention. All colored mica titanium pigments were stable to acids, but all commercially available colored mica titanium pearlescent pigments were unstable and gradually faded, and after 24 hours, commercially available Cloisonne Red turned white. The colors of Cloisonné Gold, Cloisonné Blue, and Cloisonné Green became pale and whitish, and the pearlescent luster was extremely reduced. Thus, it can be seen that the colored mica titanium pigment, which is a product of the present invention, has excellent acid stability.

■Alkali stability test 1.5 g of the colored mica titanium pigment that is a product of the present invention and 1.5 g of the commercially available colored mica titanium pearlescent pigment are each placed in a 50 ml test tube with a stopper, and a 2N aqueous solution of caustic soda is added to the test tube. After adding 30ml and dispersing, leave it on the test placket.
The color tone after 4 hours was observed with the naked eye. The results are shown in Table 5.

(Margin below) Table 5 Alkali Stability Test Results ◎ 2. Extremely stable with no change in color tone △: Gradually fades and the color tone becomes pale and whitish ×: Discolors and changes to white As is clear from the results in Table 5, The colored mica titanium-based pigment, which is a product of the present invention, is completely stable against alkali, whereas all commercially available colored mica titanium-based pearlescent pigments are unstable and gradually fade, and after 24 hours, the commercially available cloisoned Cloisonne Blue changed to white, and Cloisonne Gold and Cloisonne Green became dull and whitish in color, and their pearlescent luster was extremely reduced. Thus, it can be seen that the colored mica titanium pigment, which is a product of the present invention, has excellent alkali stability.

■Photostability test A colored mica titanium pigment, which is a product of the present invention, and a commercially available colored mica titanium pearlescent pigment are each mixed with talc (manufactured by Asada Seifun Co., Ltd.) in a ratio of 3=7. 5
Each of the samples (g) was molded into a square aluminum medium plate with a thickness of 3 mm and a -side of 20 mm, and was irradiated with a xenon lamp for 30 hours. The color tone after irradiation and the color tone before irradiation were measured using a color analyzer 607, and the color difference (ΔE) before and after irradiation was determined from the colorimetric values. The results are shown in Table 6.

(The following is a blank space) Table 6 Test Results As is clear from the results in Table 6, the colored mica titanium pigment, which is the product of the present invention, has a color difference (△E) of 0.0 between before and after irradiation.
5 or less, and the difference in color tone is almost indistinguishable to the naked eye, whereas the commercially available Cloisonne Red and Cloisonne Gold have a color difference of 35.3 and 18.0, respectively.
It was extremely large, and the change in color tone was obvious even to the naked eye.

In addition, Cloisonne Green and Cloisonne Blue had a large color difference of 6.0 and 5.2, respectively, and it was observed that a color tone change was clearly observed even with the naked eye.

■Thermal Stability Test Weigh out 3g of each of the colored mica titanium pigment, which is a product of the present invention, and the commercially available colored mica titanium pearlescent pigment, into a 20m magnetic crucible, and heat it in the atmosphere at 200°C, 300°C.
Heat treatment was performed for 2 hours under each temperature condition of 400°C and 500°C. The color of the processed powder is measured with a color analyzer 607,
The color difference (ΔE) from the pigment before treatment was determined. In addition, changes in color tone were observed with the naked eye. The respective results are shown in Table 7.

(Left below) Table 7 Thermal Stability (△E) Test As is clear from the results in Table 7, the colored mica titanium pigment, which is the product of the present invention, has a color difference of 0.5 or less to the naked eye up to 400°C. It is stable with almost no change in color tone. 5
When the temperature reaches 00°C, the color changes to yellowish white. This is because the lower titanium oxide on the surface of the mica particles was oxidized and changed to titanium oxide. That is, it can be seen that the colored mica titanium pigment, which is the product of the present invention, is stable up to temperatures below 500°C.

On the other hand, commercially available Cloisonne Red and Cloisonne Blue have a color difference of 3°2.3.5 at 200°C, and the color change is clearly visible even with the naked eye. When the temperature reaches 300°C, the color tone increases to 36.4.26.2 and changes from red to yellow-red and from blue to red-brown. That is, since the color tone of Cloisonne Red and Cloisonne Blue changes at 200° C., it can be seen that they are inferior in thermal stability. Cloisonné green has a color difference of 7.8 at 400°C, the saturation decreases, and the color changes to dark green. That is, it is stable at temperatures below 400°C, but unstable at temperatures above that. As for Cloisonné Gold, even at 500°C, the saturation is only slightly inferior, and the color difference is less than 1°0, which is highly stable.

■Dispersion (color separation) stability test 1.0 g each of the colored mica titanium pigment, which is a product of the present invention, and the commercially available colored mica titanium pearlescent pigment,
Add 0.2% by weight to a 50ml test tube with a stopper scale.
50 ml of an aqueous hexatalic acid solution was added thereto and dispersed for 30 seconds using a polytron, and the dispersion was further dispersed using ultrasound. After dispersion, let it stand still on the test stand, and immediately after leaving it undisturbed,
The dispersion state was visually observed after 5 minutes, 10 minutes, 30 minutes, and 1 hour. The results were as shown in Table 8.

(Margin below) Table 8 Water dispersibility test results ○: No sedimentation, showing good dispersibility.

△ mark: Sedimentation is progressing with color separation.

× Mark: Complete sedimentation with color separation.

As is clear from the results in Table 8, the colored mica titanium pigment, which is a product of the present invention, is uniformly dispersed even after standing for 1 hour, whereas the commercial product Cloisonne Blue and Cloisonne For red, sedimentation was observed after 5 minutes of standing, and the supernatant liquid was blue or red in color. This is simply due to the separation of the mixed navy blue and carmine. Sedimentation of Cloisonne Green was observed 30 minutes after standing, and the supernatant liquid had a darker green color than the green color of the sedimented particles.

This is simply due to the separation of the mixed chromium oxide.

Cloisonne gold remained uniformly dispersed even after standing for 1 hour.

As is clear from the above test results, the colored mica titanium pigment, which is the product of the present invention, is stable with no change at all when exposed to acids, alkalis, or light, and is 50% stable when exposed to heat.
It is stable up to temperatures below 0°C and does not change color. Furthermore, it has excellent dispersibility, does not cause color separation, and has excellent pigment properties.

[Effects of the Invention] As explained above, according to the method for producing a colored mica titanium pigment according to the present invention, since mica coated with titanium dioxide is reduced with metallic titanium, pearlescent luster and bright color tone can be obtained. It is possible to obtain a colored mica titanium-based pigment which has the following characteristics and is excellent in usability.

Claims (1)

[Claims] (1) A method for producing a colored mica titanium pigment, which comprises mixing titanium metal into mica coated with titanium dioxide and reducing the mixture at 500 to 1000°C under low oxygen conditions.