JP2002129064A - Controlling method for hue/gloss of mica-based titanium pearl pigment and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily and accurately controlling method for a hue and a gloss of a pearl pigment when producing a mica-based titanium pearl pigment. SOLUTION: When a surface of a mica is coated with titanium oxide by using an aqueous solution of titanium chloride, the hue and the gloss of the pearl pigment are controlled by changing a chlorine content/a titanium content in the aqueous solution of titanium chloride. Preferably, in the aqueous solution of titanium tetrachloride, a chlorine concentration is changed in 20-40 wt.%, and a titanium concentration is changed in 5-25 wt.%. Typically, the mica-based titanium pearl pigment is an interference-type color. While applying the above controlling method, the mica-based titanium pearl pigment is produced by suspending fine mica particles in the aqueous solution of titanium chloride, hydrolyzing the aqueous solution of titanium tetrachloride to form a film of titanium oxide on the surface of the mica, and calcining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for simply and accurately controlling the hue and gloss of a titanium oxide-coated mica-based titanium pearl pigment used for paints, cosmetics and the like, and to a mica-based titanium incorporating such control. The present invention relates to a method for producing a pearl pigment. In particular, the present invention, when producing a mica-based titanium pearl pigment by coating titanium oxide on the mica surface with a titanium chloride aqueous solution, in the titanium chloride aqueous solution, chlorine content, or titanium content, or chlorine content and By changing both the titanium content (collectively referred to as chlorine content / titanium content),
The hue / gloss control of mica-based titanium pearl pigments, which controls hue or gloss, or both hue and gloss (collectively referred to as hue / gloss), is a pillar.

[0002]

2. Description of the Related Art Pearl pigments or pearlescent pigments have conventionally been produced from natural plate-like guanine crystals collected from fish scales, but they are expensive and are mostly used at present. Among these synthetic products, mica-based titanium pearl pigments in which mica is coated with a metal oxide such as titanium oxide are rich in color, are easy to handle because they are powder, and have optical properties, light resistance, heat resistance, Because of its chemical resistance and non-toxicity, it is widely used in automotive coatings, plastics, inks and cosmetics.

[0003] Mica-based titanium pearl pigments form a film of fine particles of a metal oxide such as titanium oxide or iron oxide on the surface of a flake of natural or synthetic mica, so that the film has an optical effect. Realizes a pearl-like luster effect. Light has the property of reflecting and refracting when it enters a boundary between substances having different refractive indices.However, mica-based titanium pearl pigments having a metal oxide film on the surface reflect some light and partially reflect light. Refractive multi-layer reflections create a true pearlescent luster. Also, a thin film with a high refractive index, such as titanium oxide, reflects and refracts light both at the upper boundary of the film and at the lower boundary of the film, so that the optical thickness of the thin film (multiplied by the refractive index and the thickness) Value) satisfies a certain condition, light interference occurs. Therefore, in the titanium oxide pearl pigment coated with titanium oxide, the wavelength of the interfering light changes depending on the thickness of the titanium oxide coating, and the hue changes. Incidentally, in JP-A-59-33364, "Optics-Kozo Ishiguro, Kyoritsu Zensho, Vol. 56, p. 17
0, issued September 1972-"and USP-30878
27 ", the thickness of the hydrous titanium film deposited on the surface of the mica particles and the color change based on the light interference theory due to the increase in the thickness are gray (silver), yellow, red, yellow,
It is described as blue and green.

[0004] As described above, conventionally, in a titanium oxide pearl pigment coated with titanium oxide, the hue and gloss of the titanium oxide coating have been controlled by changing the thickness of the titanium oxide coating. However, this coating thickness is on the order of nanometers, and it has been difficult to control the coating thickness uniformly and without variation, and to control the hue and gloss of the pearl pigment.

[0005] A method of forming a titanium oxide film on a mica surface is to hydrolyze or neutralize titanyl sulfate, titanium sulfate, titanium chloride or an organic titanic acid to produce a titanium oxide hydrate or a titanium hydroxide, which is then fired. It is done by doing. Among these methods, the method of hydrolyzing titanyl sulfate or titanium sulfate aggregates the titanium oxide particles generated by sulfate ions to form a uniform titanium oxide film, but is mainly used for cosmetic anatase having a low refractive index. It is used for the production of mica-based titanium pearl pigments coated with titanium, and is inferior in both gloss and interference color to rutile-type titanium oxide-coated mica-based titanium pearl pigments hydrolyzed from titanium chloride.

Further, in the method of hydrolyzing an organic titanic acid such as alkoxytitanium, the raw material of the organic titanic acid is expensive and the cost is increased. Also, in the method of hydrolyzing titanium chloride, it is difficult to form a uniform coating due to excessive supply of titanium chloride,
In order to adjust the thickness of the titanium oxide film, strict control such as pH and temperature at the time of film formation was required.

Among the known methods of forming a titanium oxide film, in the method of hydrolyzing titanium chloride, Japanese Patent Publication No. 49-3824 discloses an aqueous titanium salt solution having a dilute concentration in a specific range. A method of simultaneously supplying an alkali metal base to an aqueous suspension of a solid substance to be coated such as mica, and controlling a titanium salt addition amount to form a titanium oxide coating while constantly maintaining a constant pH value during the coating process. Is disclosed. In JP-A-59-33364 (supra), titanium tetrachloride and a polybasic organic acid or an oxypolybasic organic acid are mixed under heating in an aqueous medium with mica fine particles, and a water-containing organic A method for producing a titanium oxide-coated mica-based titanium pearl pigment by forming a titanium oxide coating and then firing the coating is disclosed.

[0008]

The above-mentioned prior art has a certain effect in terms of forming a uniform titanium oxide film. However, when the hue and gloss of the pearl pigment are stably and precisely controlled. Strict control such as titanium chloride concentration, pH and temperature when hydrolyzing titanium chloride is required, and it is difficult to adjust, for example, a subtle interference color such as reddish color in the same series of hues.

Accordingly, an object of the present invention is to provide a method for producing a mica-based titanium pearl pigment by coating mica surface with titanium oxide with an aqueous solution of titanium chloride, the hue and luster of the pearl pigment, particularly the same series of subtle hue. An object of the present invention is to establish a method capable of easily and accurately controlling the difference and a method for producing a mica-based titanium pearl pigment incorporating the method.

[0010]

Under such circumstances, the present inventors have developed a method for controlling the hue and gloss of a pearl pigment when producing a mica-based titanium pearl pigment by coating mica surface with titanium oxide with an aqueous titanium chloride solution. As a result of intensive studies, it was found that by changing the composition of the aqueous solution of titanium chloride, which is the raw material, without changing the pH and temperature when hydrolyzing titanium chloride, the subtle hue of pearl pigments, especially of the interference color type, was changed. And that the gloss can be controlled,
The present invention has been completed. By changing the chlorine content in the aqueous titanium chloride solution, the hue of the pearl pigment can be controlled. By changing the titanium content, the gloss of the pearl pigment can be controlled. These combined controls are also possible.

That is, the method for controlling the hue / gloss of the mica-based titanium pearl pigment of the present invention comprises the steps of: providing a mica-based titanium pearl pigment by coating mica surface with titanium oxide with an aqueous titanium chloride solution; By changing the chlorine content, or the titanium content, or both the chlorine content and the titanium content (chlorine content / titanium content), the hue or gloss of the pearl pigment, or both the hue and gloss (hue / gloss) ) Are individually controlled.

Further, the method for producing a mica-based titanium pearl pigment of the present invention comprises the steps of suspending mica fine particles in an aqueous solution of titanium chloride and hydrolyzing the aqueous solution of titanium chloride in the presence of mica. To form a titanium oxide film by precipitating the mica, the mica having the oxide film formed thereon is washed with water, and then baked to produce a mica-based titanium pearl pigment. By controlling the content, or both the chlorine content and the titanium content (chlorine content / titanium content), to control the hue or gloss, or both the hue and gloss (hue / gloss) of the pearl pigment, respectively. It is characterized by.

In these methods, it is preferable that the titanium chloride aqueous solution is a titanium tetrachloride aqueous solution, the chlorine concentration in the titanium tetrachloride aqueous solution is changed in a range of 20 to 40% by weight, and the titanium concentration in the titanium tetrachloride aqueous solution is changed. Is 5
It is varied in the range of 25% by weight. Typically, mica titanium pearl pigments are of the interference color type.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The hue / gloss control method of the mica titanium pearl pigment of the present invention is effective for interference color type pearl pigments,
Among them, interference color gold is particularly effective. The interference color type means that the wavelength of the interfering light changes depending on the thickness of the titanium oxide film, and the hue changes.

In the present invention, an aqueous solution of titanium chloride is used as a raw material for coating the titanium oxide. The titanium chloride aqueous solution is a titanium trichloride aqueous solution and a titanium tetrachloride aqueous solution, and both can be used in the present invention. However, since the titanium trichloride aqueous solution needs to be oxidized in advance, the titanium tetrachloride aqueous solution is used. It is preferably used.

Known methods can be used for the production of titanium chloride. For example, an aqueous solution of titanium trichloride can be obtained by a membrane electrolysis method of an aqueous solution of titanium tetrachloride or a method of reacting titanium metal with hydrochloric acid. The aqueous solution of titanium tetrachloride can be obtained by a method in which titanium tetrachloride is gradually dropped and dissolved in pure water.

In the present invention, the hue / gloss of the resulting mica-based titanium pearl pigment can be controlled by changing the chlorine / titanium content in the titanium chloride aqueous solution. If used,
Chlorine content is 20-40%, preferably 25-40%,
Particularly preferably, it is varied in the range of 28 to 38%, and the titanium content is 5 to 21%, preferably 10 to 20%,
Particularly preferably, it is changed in the range of 13 to 19%.

Here, the chlorine content means the total amount of chlorine in titanium chloride such as titanium tetrachloride and chlorine in free hydrochloric acid in an aqueous solution of titanium chloride. Further, as described above, the chlorine content in the titanium chloride aqueous solution is changed. However, when the titanium chloride concentration is changed, the thickness of the generated titanium oxide film varies, and specifically, the liberation in the aqueous solution is caused. Change the concentration of hydrochloric acid.

The titanium tetrachloride aqueous solution as described above can be prepared by various methods, and specific preparation methods are described below.

First, (a) by supplying titanium tetrachloride into water, the titanium tetrachloride and water are contacted and reacted to form an aqueous solution of titanium tetrachloride, and (b) when titanium oxide hydrate precipitates. Means that titanium tetrachloride is added in an amount of 0.1
By supplying at a rate of at least mol / hour, the chlorine concentration of the reaction system is increased to, for example, at least 3 mol / L, and the precipitated titanium oxide hydrate is dissolved in the reaction system. Thereafter, the production of an aqueous solution of titanium tetrachloride is continued, and (c) thereafter, titanium tetrachloride and water are independently and simultaneously supplied to the reaction system in which the titanium oxide hydrate is dissolved to precipitate the titanium oxide hydrate. The required amount of titanium tetrachloride aqueous solution is generated while avoiding.

In the above-mentioned preparation method, step (a)
In (c) at least in step (c), the electric conductivity of the produced titanium tetrachloride aqueous solution was measured, and desirably at the same time by measuring the specific gravity of the titanium tetrachloride aqueous solution produced in step (c). The supply amount of titanium tetrachloride and / or water is controlled based on the electric conductivity of the titanium tetrachloride aqueous solution and preferably the specific gravity of the titanium tetrachloride aqueous solution.

In short, the generation of precipitates generated during initial dissolution is suppressed through the measurement of the electric conductivity of the produced titanium tetrachloride aqueous solution, and even if the precipitates are deposited, the heat of dissolution is used to cause re-dissolution. Preventing precipitation of hydrolyzed solids due to partial overheating in the titanium tetrachloride dropping part,
In addition, in the reaction of the step (c), the control of the chlorine concentration and the titanium concentration of the titanium tetrachloride aqueous solution is performed through the measurement of the electric conductivity of the generated titanium tetrachloride aqueous solution and the measurement of the specific gravity of the generated titanium tetrachloride aqueous solution. It can be carried out.

The titanium tetrachloride aqueous solution produced as described above is intermittently or continuously withdrawn from the reaction system to produce a titanium tetrachloride aqueous solution. When the concentration of chlorine or titanium in the aqueous solution is adjusted, the produced tetrachloride is produced. Air or an inert gas can be brought into contact with the titanium aqueous solution. Specifically, an operation (aeration) of blowing air or an inert gas into the produced titanium tetrachloride aqueous solution is performed. As an aeration method, a method of immersing a nozzle for supplying air or an inert gas in an aqueous solution of titanium tetrachloride and performing bubbling, or introducing an aqueous solution of titanium tetrachloride from the top of a column filled with the packing material, A method in which air or an inert gas is introduced from the lower portion and brought into contact with and aerated, or the like is employed. The amount of air or inert gas contacted at this time varies depending on the titanium concentration and chlorine concentration in the titanium tetrachloride aqueous solution as the final product. The amount of gas is usually 10 ~
It is 200 L, preferably 30-100 L. The concentration of titanium or chlorine in the aqueous solution of titanium tetrachloride can be adjusted by aeration.

Next, a titanium oxide film is formed on the mica surface using the above-mentioned aqueous solution of titanium chloride. A specific method will be described below.

With regard to the mica (mica) to be used, commercially available general-purpose mica for pearl pigments can be used. The average particle size of the mica is generally in the range of 1 to 15 μm. The mica is suspended in an aqueous hydrochloric acid solution, and an aqueous solution of titanium tetrachloride is dropped into the suspension. The suspension temperature is 50-100 ° C, preferably 70-90 ° C. At this time, a neutralizing agent such as sodium hydroxide is simultaneously dropped into the suspension, and the pH of the suspension is adjusted.
Is controlled to 0.5 to 3, preferably 1.0 to 3, hydrolysis of the titanium tetrachloride aqueous solution occurs. By hydrolyzing the titanium tetrachloride aqueous solution in the presence of mica in this manner, titanium oxide is deposited on the mica surface, and a titanium oxide film is formed. Thereafter, the pH of the suspension of mica on which the oxide film was formed was adjusted to a neutral region, and the mica was washed with water.
Firing at 00 to 1000 ° C, preferably 750 to 900 ° C, to obtain a mica-based titanium pearl pigment.

As described above, the hue of the pearl pigment can be controlled by forming a titanium oxide film on the mica surface by the above-described method using an aqueous solution of titanium chloride having a changed chlorine content. As is well known, the hue is a color coordinate a ^* , b ^* (+ a ^* : red direction, -a ^* : green direction, + b ^* : yellow direction, -b ^* : "L ^* a ^* b ^* color system"). (Blue direction). Specifically, by lowering the chlorine content in the titanium chloride aqueous solution,
The value of the hue a-axis of the pearl pigment can be set to the minus side, and conversely, by increasing the chlorine content in titanium chloride, the value of the hue a-axis can be set to the plus side. At the same time, the value of the b-axis is increased by lowering the chlorine content in titanium chloride. Control of the chlorine content can be performed in the process of producing the titanium chloride aqueous solution as described above.

The gloss can be controlled by controlling the titanium content in the titanium chloride aqueous solution. Here, “gloss” means that when irradiating a sample with white light, 60 g
It is evaluated by measuring the intensity of reflected light at an angle of 20 degrees. Increasing the titanium content increases the reflected light intensity and increases the gloss. The titanium content is controlled by changing the dilution of titanium chloride.

By changing both the chlorine content and the titanium content in the titanium chloride aqueous solution, both the hue and gloss of the pearl pigment can be controlled.

For example, the total amount of titanium tetrachloride added to mica is first determined so as to obtain a titanium oxide film thickness necessary for the development of a specific hue, such as a yellow (gold) series, and the same series is determined by the control method according to the present invention. Hue control can be performed. By changing the total amount of titanium tetrachloride added to mica, the thickness of the titanium oxide film can be changed, and fine hue control in another hue series can be performed. It is a major feature of the present invention that the subtle hue and gloss of the pearl pigment of the interference color type can be controlled.

[0030]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Note that this is merely an example and does not limit the present invention.

(Example 1) (Preparation of pearl pigment) In a vessel equipped with a stirrer, an average particle size of 1
A hydrochloric acid-based suspension of pH 2.0 containing 5% by weight of raw material mica (scale mica) of １５15 μm was prepared, stirred, and kept at 80 ± 5 ° C. Then, in this suspension,
An aqueous solution of titanium tetrachloride having a chlorine content of 39.8% by weight and a titanium content of 15.6% by weight was dropped at a dropping rate of 4 kg / hour. At the same time, a 15% by weight aqueous solution of sodium hydroxide was added dropwise so that the pH of the suspension was 2.0 ± 0.2. In this way, the aqueous solution of titanium tetrachloride was hydrolyzed, to the raw mica particle surfaces to precipitate a hydrate of titanium oxide, titanium tetrachloride so that 40 to 45% by weight of TiO ₂ with respect to mica The aqueous solution was dropped. After the dropwise addition of the predetermined amount of the aqueous solution of titanium tetrachloride was completed, an aqueous solution of sodium hydroxide was added to adjust the pH of the suspension to 7.3. Then, the suspension was cooled to room temperature, filtered and washed with water. Thereafter, the mica having the titanium oxide film formed thereon was fired at 800 ° C. for 2 hours to obtain a pearl pigment.

(Evaluation of Hue and Gloss) Hue and gloss were evaluated in accordance with JIS Z 8730 by the following method. 1 g of the pearl pigment obtained above
Was mixed with an applicator to a coating thickness of 4 mil (1/1000 inch) on black and white glossy paper, dried at room temperature, and then evaluated for the gloss color of the yellow interference color panel. . Hue (hue a-axis value, b-axis value)
Was measured using a CM-1000 color tone meter manufactured by Minolta, and pearl luster (60 ° and 20 °) was measured using an IG-330 model manufactured by Horiba, Ltd. The hue having the strongest redness in Examples 1 to 6 was 1
The ranking was visually determined. Further, regarding the gloss, the highest gloss in Examples 1 to 6 was ranked first, and was ranked visually. Table 1 shows the obtained results.

(Examples 2 to 6) Example 1 shown in Table 1
A pearl pigment was prepared and evaluated in the same manner as in Example 1 except that an aqueous solution of titanium tetrachloride having a changed chlorine content and titanium content was used. The results are shown in Table 1.

[0034]

[Table 1]

From the results in Table 1, it can be seen that the higher the chlorine concentration in the titanium tetrachloride aqueous solution, the more reddish the yellow (gold) series hue becomes.
It can be seen that the gloss value increases and the gloss increases as the titanium concentration in the titanium tetrachloride aqueous solution increases (the titanium concentration increases in Examples 2, 4, 1, and 2).
3, 5, 6). In FIG. 1, "L ^* a ^*
b ^* color system "color coordinates a ^* , b ^* (+ a ^* : red direction,-
a ^* : green direction, + b ^* : yellow direction, -b ^* : blue direction). It can be seen that the higher the chlorine concentration, the more the redness in the yellow phase slightly increases.

[0036]

As described above, according to the method for controlling the hue of a mica-based titanium pearl pigment of the present invention, the chlorine content / titanium content in the raw material titanium chloride aqueous solution can be changed easily and easily. Hue of pearl pigment with high accuracy /
Gloss can be controlled. It is a major feature of the present invention that the subtle hue and gloss of the pearl pigment of the interference color type can be controlled.

[Brief description of the drawings]

FIG. 1 shows color coordinates a ^* , b ^* (+) of “L ^* a ^* b ^* color system”.
a ^* : Red direction, -a ^* : Green direction, + b ^* : Yellow direction, -b ^* :
FIG. 9 is a coordinate diagram showing a change in hue of Examples 1 to 6 in a blue direction).

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yanagita Higashi 6-1, 1-1 Ichimachi, Tachikawa-shi, Tokyo Inside Nippon Kenken Kogyo Co., Ltd. (72) Iku Yagura 6-1, Ichibancho, Tachikawa-shi, Tokyo Address 2 Nippon Kenken Kogyo Co., Ltd. F term (reference) 4J037 AA26 CA05 EE03 EE14 EE26 EE28 EE43 FF03 FF13 FF22 FF25

Claims (10)

[Claims] When producing a mica-based titanium pearl pigment by coating mica surface with titanium oxide using an aqueous solution of titanium chloride, a chlorine content or a titanium content, or a chlorine content and a titanium content in the titanium chloride aqueous solution. A method for controlling the hue / gloss of a mica-based titanium pearl pigment, wherein the hue or the gloss, or both the hue and the gloss, of the pearl pigment are respectively controlled by changing both the amounts. 2. The method for controlling the hue / gloss of a mica-based titanium pearl pigment according to claim 1, wherein the aqueous titanium chloride solution is an aqueous titanium tetrachloride solution. 3. The method for controlling the hue / gloss of a mica-based titanium pearl pigment according to claim 2, wherein the chlorine concentration in the aqueous titanium tetrachloride solution is 20 to 40% by weight. 4. The method for controlling the hue / gloss of a mica-based titanium pearl pigment according to claim 2, wherein the titanium concentration in the titanium tetrachloride aqueous solution is 5 to 25% by weight. 5. The method for controlling the hue / gloss of a mica-based titanium pearl pigment according to claim 1, wherein the mica-based titanium pearl pigment is an interference color type. 6. A titanium oxide film is formed by suspending mica fine particles in an aqueous solution of titanium chloride and hydrolyzing the aqueous solution of titanium chloride in the presence of mica to precipitate titanium oxide on the surface of mica. The method for producing a mica-based titanium pearl pigment by rinsing after washing the mica having a coating thereon with water,
By adjusting the chlorine content, or the titanium content, or both the chlorine content and the titanium content, the hue, or gloss, or both the hue and the gloss of the pearl pigment are controlled, respectively. Pigment manufacturing method. 7. The method for producing a mica-based titanium pearl pigment according to claim 6, wherein the aqueous titanium chloride solution is an aqueous titanium tetrachloride solution. 8. The method for producing a mica-based titanium pearl pigment according to claim 7, wherein the chlorine concentration in the aqueous titanium tetrachloride solution is 20 to 40% by weight. 9. The method for producing a mica-based titanium pearl pigment according to claim 7, wherein the titanium concentration in the titanium tetrachloride aqueous solution is 5 to 25% by weight. 10. The method for producing a mica-based titanium pearl pigment according to claim 6, wherein the mica-based titanium pearl pigment is an interference color type.