JPH0420031B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] 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. The manufacturing method for such mica titanium pigments is as follows:
There is also a vacuum deposition process, but the most common method is to hydrolyze an aqueous solution of an inorganic acid salt of titanium (e.g. titanyl sulfate) in the presence of mica, precipitate hydrated titanium dioxide on the mica surface, and then heat it. Kosho 43-
(See Publication No. 25644). 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 is usually silver when the amount of titanium dioxide is between 10 and 26% by weight of the product, gold between 26 and 40%, red, blue in the range of 40 and 50% in the direction of increasing titanium dioxide layer. , changes to green and further 50-60%
In this case, high order interference colors can be 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 coloring pigment added. 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 pigments to which carbon black is added, the carcinogenicity of 3,4-benzpyrene, which may be mixed into the carbon black, becomes a problem, and green mica titanium pigments to which chromium oxide is added In this case, the safety of hexavalent chromium is often questioned, 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 causing 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 titanium dioxide on the surface of mica particles to lower-order titanium oxide, 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 containing a colored pigment, has a pearlescent luster, and is excellent in safety. That is, the present invention mixes metallic titanium with mica coated with titanium dioxide, and under low oxygen conditions
This is a method for producing a colored mica titanium pigment characterized by reduction at 1000°C. 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.
However, in some cases, it is also possible to use biotite or the like. Although the particle size is not particularly limited, the particle size of commercially available mica is 1 to 50 μm, and among these, the smaller the particle size and the flatter the particle shape as possible, the more beautiful the color tone will be when used as a colored mica titanium pigment. Easily exhibits pearlescent luster. Then, metallic titanium is mixed with the mica titanium pigment, and the mixture is heated to 500 to 1000°C, preferably 700°C to
Heat reduction at 900℃. 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. Normally, titanium dioxide is 0 to 60 parts per 100 parts by weight of mica, and lower titanium oxide is 0.01 to 60 parts by weight.
Amounts up to 6 parts by weight can be coated. The amount of lower titanium oxide per 100 parts by weight of mica
If less than 0.01 part 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 become extremely poor and the particles will become more agglomerated. 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. Amount of titanium dioxide and lower titanium oxide The sample before and after the reduction treatment were each ground using a Meno ball mill.
Made mica amorphous. The sample was subjected to x-ray diffraction (Cu-
The intensity of the diffraction lines of titanium dioxide and lower-order titanium oxide was determined using the powder measurement method of Kα rays.
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. Amount of low-order titanium oxide Since all low-order titanium oxides are converted to titanium dioxide by firing in the atmosphere, the amount of low-order titanium oxides was quantified by conducting gravimetric analysis on the sample subjected to the reduction treatment. That is, approximately 5 g of a sample was accurately weighed into a 20 ml 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. Example 1 50 parts of mica was added to 500 parts of ion-exchanged water and thoroughly stirred to be uniformly dispersed. 312.5 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, it was filtered, washed with water, and fired at 900°C to obtain 100 parts of mica coated with titanium dioxide (mica titanium). Next, 1.2 parts of metallic titanium is added to 100 parts of the obtained mica titanium.
The mixture was heated and reduced at 800° C. for 4 hours under a vacuum of 10 ⁻³ torr or less using an oil diffusion pump. 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 amount 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, and lower titanium oxide is 40.5 parts by weight per 100 parts by weight of mica. Titanium was found to be 9.5 parts by weight. Examples 2 to 5 50 parts of each of four types of commercially available (manufactured by Marl Inc., USA) mica titanium-based pearlescent pigments having interference colors were taken, the amount of metallic titanium mixed was varied, and the mixture was mixed with a diffusion pump for 10 ^- The mixture was heated and reduced at 800°C for 4 hours under a vacuum of ³ torr or less. 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 H. lightness V. saturation C). The results are shown in Table 1 below.

[Table] The pigment properties of the colored mica titanium pigments obtained in Examples 1 to 5 above were tested. For comparison, the pigment properties of a colored mica titanium-based pearlescent pigment (a conventional mica titanium-based pigment with a colored pigment added) commercially available from Marl Corporation of the United States 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] The composition of the commercially available product is shown in Table 3 below.

[Table] 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 colored mica titanium-based pigments of the present invention and commercially available colored mica titanium-based pearlescent pigments
Place each in a 50ml test tube with a stopper, and add
After adding 30 ml of 2N hydrochloric acid aqueous solution and dispersing, the mixture was allowed to stand still in a test tube stand, and the color tone after 24 hours was observed with the naked eye. The results are shown in Table 4.

[Table] As is clear from the results in Table 4, all of the colored mica titanium pigments that are products of the present invention were stable against acids, but all of the commercially available colored mica titanium pearlescent pigments were not. It was stable and gradually faded, and after 24 hours, the commercially available Cloisonne Red turned white, and the colors of Cloisonne Gold, Cloisonne Blue, and Cloisonne Green became pale and whitish, 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 acid stability. Alkali stability test 1.5 g of the colored mica titanium-based pigment of the present invention and the commercially available colored mica titanium-based pearlescent pigment
Place each in a 50ml test tube with a stopper, and add
After adding and dispersing 30 ml of 2N caustic soda aqueous solution, the mixture was left to stand in a test tube rack and the color tone was observed with the naked eye after 24 hours. The results are shown in Table 5.

[Table] As is clear from the results in Table 5, the colored mica titanium pigment, which is the product of the present invention, is completely stable against alkalis, whereas all commercially available colored mica titanium pearlescent pigments are unstable. The color gradually faded, and after 24 hours, the commercially available Cloisonet and Cloisonne Blue changed to white, and the colors of Cloisonne Gold and Cloisonne Green became pale and whitish, and their pearlescent luster was extremely reduced. Thus, it can be seen that the colored mica titanium pigment, which is the product of the present invention, has excellent alkali stability. Photostability test The colored mica titanium pigment, which is a product of the present invention, and the commercially available colored mica titanium pearlescent pigment are each mixed with talc (manufactured by Asada Seifun Co., Ltd.) in a ratio of 3:7, and 2.5 g of the mixture is 3mm thick each, one side
It was molded into a 20 mm square aluminum medium plate, 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.

【table】

[Table] As is clear from the results in Table 6, the color difference (△E) of the colored mica titanium pigment, which is a product of the present invention, before and after irradiation is 0.5 or less, which is almost unchanged, and there is almost no difference in color tone with the naked eye. On the other hand, commercial products Cloisoneret and Cloisonegol had an extremely large color difference of 35.3 and 18.0, respectively, and the change in color tone was clear even to the naked eye. In addition, Cloisonne Green and Cloisonne Blue have a color difference of 6.0 and 5.2, respectively.
It was observed that there was a noticeable change in color tone even with the naked eye. Thermal Stability Test The colored mica titanium pigment which is the product of the present invention and the commercially available colored mica titanium pearlescent pigment were tested separately.
Weighed 3g into a 20ml magnetic crucible and placed it in the atmosphere for 200 ml.
Heat treatment was performed for 2 hours under each temperature condition of 300°C, 300°C, 400°C, and 500°C. The color of the powder after treatment is measured using a color analyzer 607, and the color difference (△E) from the pigment before treatment is determined.
I asked for In addition, changes in color tone were observed with the naked eye. The respective results are shown in Table 7.

【table】

[Table] As is clear from the results in Table 7, the colored mica titanium pigment, which is the product of the present invention, is stable with a color difference of 0.5 or less up to 400°C, with almost no change in color tone to the naked eye. When the temperature reaches 500℃, 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, the commercial products Cloisonne Red and Cloisonne Blue have a color difference of 3.2 and 3.2, respectively, at 200℃.
3.5, and the change in color tone is clearly visible to the naked eye. When the temperature reaches 300℃, the color tone increases to 36.4 and 26.2, and the color changes from red to yellow-red and from blue to red-brown. In other words, Cloisonne red and Cloisonne blue change color tone at 200°C, indicating that they are inferior in thermal stability. Cloisonné green is 400
At ℃, the color difference becomes 7.8, 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 degrees Celsius, the saturation is only slightly inferior, and the color difference is less than 1.0, which is highly stable. Dispersion (color separation) stability test Put 1.0 g each of the colored mica titanium-based pigment, which is a product of the present invention, and the commercially available colored mica titanium-based pearlescent pigment into a 50 ml test tube with a stopper scale, and add 0.2 weight % hexatalic acid aqueous solution was added and dispersed for 30 seconds using a polytron, and this dispersion was further dispersed using ultrasonic waves. After dispersion, let stand in a test tube stand, immediately after standing, after 5 minutes, after 10 minutes,
The dispersion state was visually observed after 30 minutes and 1 hour. The results were as shown in Table 8.

[Table] △ 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 products Cloisonne Blue and Cloisonne Red are uniformly dispersed. , 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. Cloisonné green is
Sedimentation was observed after 30 minutes of 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 that is the product of the present invention is stable against acids, alkalis, and light, and is stable under heat at temperatures below 500°C. Stable up to temperatures of
Does not cause color change. 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 with mica coated with titanium dioxide and reducing the mixture under vacuum at 500 to 1000°C.