JPH08259840A - Red-based pigment and its production - Google Patents

Abstract

PURPOSE: To obtain red-based pigment having high chroma from red-purple to red-green and continuous color tone and excellent in stability. CONSTITUTION: This red-based pigment is obtained by coating the surface of platy particles with an iron oxide layer and further coating the surface of the iron oxide-coated platy particles with a titanium compound layer containing titanium dioxide and has color tone of red purple to red coated with a titanium compound layer. In the red-based pigment, optical layer thicknesses of the iron oxide layer and titanium compound layer are each preferably 180-320nm and 15-220nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a red pigment and a method for producing the same, and more particularly to improvement of a red pigment using an inorganic material and a method for producing the same.

[0002]

2. Description of the Related Art Red pigments are widely used in various fields such as cosmetics, vehicle paints, general paints, plastics, inks, synthetic leather, printing, sundries, furniture, ornaments, building materials and general sundries. As a conventional general red pigment,
Many of them use a red organic substance such as carmine, but they have various drawbacks such as deterioration by fading due to light, and the problem of safety remains.

On the other hand, it is well known that red iron oxide is used as an inorganic red pigment. That is, flaky mica particle surfaces coated with red iron oxide, mica particle surfaces coated with titanium dioxide and further coated with iron oxide, or plate-shaped red iron oxide are used. These inorganic red pigments using red iron oxide have excellent advantages such as high safety and high light resistance.

[0004]

However, the reddish pigment using the red iron oxide is limited to brownish red which is a color peculiar to the iron oxide, and has various reddish hues like organic pigments. It was not possible to obtain a red pigment exhibiting the appearance color of. Of course, it is possible to change the color tone of the pigment by, for example, coating the surface of the mica particle with red iron oxide and an inorganic substance having another color tone. In this case, a mixture of plural kinds of substances is formed on the surface of the mica particle. As a result of coating, there is a problem that the coating operation itself is difficult and the lightness is remarkably lowered because light is absorbed by each substance, and gradually approaches black.

In recent years, a red pigment was reported in which iron oxide-coated mica was further coated with an aluminum compound, and a red color of orange to red-blue was exhibited by applying the interference effect of light (JP-A-6-100784). . Although the red pigment coated with the aluminum compound is an inorganic pigment, a bright red hue can be obtained, but its color range is orange to red blue, and a red purple to red green hue is obtained. If this is done, there is a problem that the layer thickness of the aluminum compound becomes thicker, the saturation is lowered and the color tone becomes darker, and in some cases agglomeration occurs to make manufacturing difficult.

The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is a red pigment consisting of only an inorganic substance having a high lightness and saturation and a vivid red-purple to red-green color tone. And to provide a manufacturing method thereof.

[0007]

Means for Solving the Problems As a result of intensive studies by the present inventors in order to achieve the above object, the surface of plate-like particles was coated with iron oxide, and the surface of the plate-like particles coated with iron oxide was coated with a titanium compound. It was found that by coating, a bright red-purple to red-green appearance color different from the hue of red iron oxide itself can be obtained, and the present invention has been completed. That is, the red pigment according to claim 1 of the present invention is a titanium compound comprising a plate-like particle, an iron oxide layer coating the surface of the plate-like particle, and a titanium compound containing titanium dioxide coating the surface of the iron oxide. And a layer having a color tone of reddish purple to reddish green.

The red pigment according to claim 2 has an optical layer thickness of iron oxide covering the surface of the plate-like particles of 180 to 32.
The optical layer thickness of the titanium compound layer, which is 0 nm and is composed of a titanium compound containing titanium dioxide and covers the iron oxide surface, is 15 to 220 nm, and has a reddish purple to red green color tone.

Further, in the manufacturing method according to claim 3, the amount of iron oxide to be coated on the plate-like particles is 80 to 140% by weight.
The iron oxide-coated plate-like particles are formed by coating the plate-like particles with iron oxide by a deposition method from a coating bath containing a precursor of the iron oxide so that the ratio becomes The amount of titanium compound including titanium dioxide to be coated is 3
A titanium compound-coated iron oxide-coated plate by coating the iron oxide-coated plate-like particles with a titanium compound by a deposition method from a coating bath containing a precursor of the titanium compound containing titanium dioxide in an amount of about 50% by weight. Forming a red particle and forming a particle of the titanium compound, and baking the titanium oxide-coated iron oxide-coated plate-shaped particle at 300 to 900 [deg.] C. to obtain a reddish purple to red-green color tone. .

The structure of the present invention will be described in more detail below. The plate-like particles that form the basis of the present invention are muscovite mica, biotite, phlogopite, synthetic mica, phlogopite, lithia mica,
Examples thereof include talc, kaolin, sericite, plate silica, plate alumina, plate titanium dioxide, titanium mica, titanium powder, and stainless powder. The particle size of the plate-like particles is not particularly limited, but when used as a pigment for general industrial products such as cosmetics, the particle size is about 1 to 50 μm,
It is preferable that the shape is as flat as possible because a beautiful color tone is easily expressed.

In the present invention, the iron oxide-coated plate-like particles obtained by coating the surface of the plate-like particles with iron oxide are used as an intermediate. The iron oxide coated is α-Fe ₂ O ₃ , γ-Fe ₂ O ₃
Etc. refers to red to brown iron oxide. In the present invention, these may be coated alone, or may be coated in the form of a mixture of two or more kinds. Further, hydrated iron oxide FeO (OH) or black iron oxide (Fe ₃ O ₄ ) may be oxidized to Fe ₂ O ₃ in the final firing step. Further, iron oxide-coated plate-like particles such as commercially available iron oxide-coated mica can be used as an intermediate for the red pigment of the present invention.

Here, the amount of iron oxide to be coated is preferably such that the optical layer thickness of the iron oxide layer is 180 to 320 nm, and specifically, the average particle diameter of the plate-like particles. When the particle size is 20 μm, it is 80
˜140 wt%, preferably 100-120 wt%. When the amount of coated iron oxide is less than 80% by weight, the reddish color tone tends to be weak, and 140% by weight
If it exceeds, the color tone of iron oxide is emphasized, and the color tone is brownish peculiar to iron oxide, which is not preferable. In addition,
Here, the optical layer thickness means the geometric layer thickness multiplied by the refractive index.

On the other hand, the titanium compound used in the present invention is not limited to hydrated titanium dioxide TiO ₂ (H ₂ O) and TiO as long as it contains titanium dioxide TiO ₂ as an essential component.
₂ (2H ₂ O) and low-order titanium oxide TiO _{2 -X} (x = 0 to
1) etc. may be mixed. In the red pigment according to the present invention, the amount of the titanium compound coated is preferably such that the titanium compound layer has an optical layer thickness of 15 to 220 nm, and the average particle diameter of the plate-like particles is 20 μm. In the case of, the amount of the titanium compound is 3 to 50% by weight, preferably 10 to 30% by weight, based on 100% by weight of the iron oxide-coated plate-like particles as the intermediate.

The amount of the titanium compound coated is 3% by weight based on 100% by weight of the iron oxide-coated plate-like particles as the intermediate.
If it is less than 40% by weight, the original color tone of iron oxide cannot be adjusted, and if it exceeds 40% by weight, the saturation is remarkably lowered. When the amount of the titanium compound to be coated is 35% by weight or more based on 100% by weight of the plate-shaped particles coated with the intermediate iron oxide, a red-green appearance color is obtained, and below that, a reddish-purple appearance is obtained. The color is obtained.

In the step of coating the iron oxide-coated plate-like particles, which is an intermediate of the present invention, with the titanium compound, the final firing temperature is 300 to 900 ° C, preferably 350 to 80 ° C.
0 ° C. If the firing temperature exceeds 900 ° C., particle aggregation occurs, which is not preferable. Examples of the method for producing the red pigment according to the present invention include the following methods.

That is, as a method of coating the surface of the plate-like particles with iron oxide, plate-like particles such as commercially available muscovite pigment are dispersed in water, and iron (I) chloride chloride, iron (II) chloride, sulfuric acid ( I)
Aqueous solutions of iron salts such as iron, iron (II) sulfate, iron (I) nitrate, iron (II) nitrate, etc. and alkaline aqueous solutions such as sodium hydroxide, potassium hydroxide etc. are added little by little at the same time while keeping the pH constant. Then, it is coated with hydrated iron oxide by neutralization decomposition,
This is calcined at a high temperature of 300 to 800 ° C., or a commercially available muscovite pigment is dispersed in water, and chloride (I) chloride is added to this.
An aqueous solution of an iron salt such as iron, iron (II) chloride, iron (I) sulfate, iron (II) sulfate, iron (I) nitrate, iron (II) nitrate, etc. and urea are added in advance, and the amount is 80- A method of heating to 100 ° C. for neutralization and decomposition, coating with hydrated iron oxide and then firing at a high temperature of 150 to 800 ° C., a method of vaporizing an iron compound at a high temperature and directly depositing it on plate-like particles, etc. Is mentioned.

The following are examples of methods for coating the intermediate of the present invention coated with iron oxide with a titanium compound. That is, iron oxide-coated plate-like particles are dispersed in an aqueous solution of an inorganic acid salt of titanium such as titanyl sulfate or titanium tetrachloride, and hydrolyzed by heating to precipitate hydrous titanium oxide on the surface of the iron oxide-covered plate-like particles. After this, 30
A method of baking at a high temperature of 0 to 900 ° C, or dispersing iron oxide-coated plate-like particles in water, and then adding an aqueous solution of an inorganic acid salt of titanium such as titanyl sulfate or titanium tetrachloride and sodium hydroxide or potassium hydroxide Alkaline aqueous solution such as is added little by little at the same time while keeping the pH constant, and is coated with hydrated titanium oxide by neutralization decomposition.
And a method in which metallic titanium is vapor-deposited on the iron oxide-coated plate-like particles by a vacuum vapor deposition method, and then this is fired at a high temperature of 300 to 900 ° C. in the atmosphere.

[0018]

As described above, the red pigment according to the present invention uses the titanium compound in order to adjust the color tone of red iron oxide. That is, a general pigment uses a substance that absorbs only light of a specific wavelength and reflects light of other wavelengths. When the pigment is irradiated with white light, which is an aggregate of light of various wavelengths, only the light component of a specific wavelength is absorbed, and the color tone of the pigment is defined by reflected light having a complementary color relationship with the absorbed light. .

That is, in red iron oxide, the brownish red color which is a color peculiar to iron oxide corresponds to the reflected light. Further, in the case of using a general idea of a pigment, it is necessary to add a substance that absorbs light in other wavelength regions in order to adjust the color of the pigment.

However, in this case, the absorption wavelength band is widened, and the color tone of the pigment gradually approaches an achromatic color and the saturation decreases. Therefore, the present inventors decided to adjust the color tone of the iron oxide-coated particles by using the interference effect of light. That is, when the surface of the plate-like particles (mica) is coated with iron oxide, and the iron oxide-coated particles are further coated with a titanium compound, the pigment structure is constructed as schematically shown in FIG.

Here, the mica 10 is in the shape of a thin piece, and the iron oxide 12 is coated in a thin layer on the periphery thereof. The iron oxide layer 12 is further covered with a titanium compound 14 containing titanium dioxide. The mica 10 and the titanium compound 14 are white and have high light transmittance, and the iron oxide layer 12 is brownish red as described above.

When such a pigment is irradiated with white light 16, part of the irradiation light 16 becomes white light 18 reflected on the surface of the titanium compound layer 14, while light 20 reflected by the surface of the iron oxide layer 12 is reflected. Is absorbed in part of the wavelength range by iron oxide, resulting in brownish red light. Further, the reflected light 22 from the surface of the mica 10 is reflected as a specific wavelength light depending on the layer thickness of the iron oxide layer 12 and the titanium compound layer 14. For example, the total layer thickness obtained by adding the layer thicknesses of the iron oxide layer 12 and the titanium compound layer 14 is obtained as reflected light of violet at 270 nm, blue at 310 nm, and green at 360 nm.

Then, for example, the total layer thickness obtained by adding the layer thicknesses of the iron oxide layer 12 and the titanium compound layer 14 is 2 as the optical layer thickness.
If it is 70 nm, the purple reflected light 22 and the white reflected light 18
Causes interference, and the interference light and the red reflected light 20 are mixed with each other to obtain reddish purple reflected light (color tone) having a sharp color tone.

That is, as shown in FIG. 2, the white reflected light 18 and the reflected light 22 have an optical path difference L corresponding to twice the total thickness of the titanium compound layer 14 and the iron oxide layer 12. Further, the reflected light 18 is out of phase with the incident light 16 when reflected by the surface of the titanium compound layer 14. Therefore,
A light component having a wavelength as shown in FIG. 2A in the reflected light 22 and a light component having the same wavelength in the reflected light 18 are deviated by one wavelength due to an optical path difference, and a peak of the light component of the reflected light 22. Since the part of is located at the valley of the light component of the white reflected light 18, the two cancel each other out and disappear in appearance as shown in FIG.

However, as shown in FIG. 3D, in the case of a light component having a wavelength twice that of the above-mentioned (A), the respective light components of the reflected light 22 and the white reflected light 18 have peaks and valleys of both. The portions of are overlapped, and amplitude amplification is performed as shown in FIG. As a result, only the light of the specific wavelength of the reflected light 18 is emphasized, and a much sharper color tone can be obtained as compared with the reflected light of iron oxide itself. The red pigment according to the present invention is coated with a titanium compound. However, since the refractive index of the titanium compound is not so different from the refractive index of iron oxide, the incident light at the interface between the iron oxide 12 and the titanium compound layer 14 is incident. Light reflection is almost negligible.

In the present invention, since the color tone is adjusted by the interference action as described above, the optical path difference for causing the interference action is an important requirement. As is clear from FIG. 2, when the optical path difference is the same as the wavelength of light or an integral multiple thereof, the light intensity in the wavelength region is substantially reduced, and the optical path difference is an integral multiple of the wavelength of light + half wavelength. In that case, the light intensity in the wavelength range is substantially increased. Therefore, the optical path difference must be adjusted so as to adjust the intensity of light having a wavelength in the visible light range.

As described above, the red pigment according to the present invention has excellent lightness and saturation by utilizing the light interference depending on the layer thickness of the titanium compound layer 14 and the iron oxide layer 12. A reddish pigment of reddish purple to reddish green can be obtained. Moreover, since the red pigment is basically formed of an inorganic substance composed of iron oxide and a titanium compound, it has stability, safety, light resistance, acid resistance, alkali resistance, solvent resistance, heat resistance, etc. Is also very good.

[0028]

EXAMPLES Hereinafter, the red pigment and the method for producing the same according to the present invention will be described in more detail with reference to Examples. The present invention is not limited to these examples. Further, the compounding amounts are all shown by weight%. Relationship between color tone and layer thickness First, the relationship between the layer thickness and color tone of the titanium compound layer, which is a feature of the present invention, will be described. Here, red pigments having various titanium compound layer thicknesses were formed by the following method, and their color tones were examined.

50 g of commercially available muscovite (average particle size 30 μm)
Was dispersed in 500 ml of water, and a predetermined amount of 10 wt% ferric chloride (hexahydrate) was added at a rate of 5 ml per minute while heating at 90 ° C. and stirring. At this time, 0.5N sodium hydroxide aqueous solution was added at the same time to adjust the pH to 4.5-
Hold at 5.0. Then, after filtering and drying the product, 5
It was baked at 00 ° C. for 2 hours to obtain iron oxide-coated mica.

Next, 80 g of the obtained iron oxide-coated mica and 1000 ml of an aqueous solution in which a predetermined amount of titanyl sulfate (dihydrate) was dissolved.
Was heated and stirred in the boiling state for 4 hours, washed with water, filtered, dried, and fired in the air at 800 ° C. to obtain titanium dioxide-coated iron oxide-coated mica. The color tone is as follows: 1 g of red pigment is uniformly dispersed in 15 g of nitrified cotton lacquer,
This was uniformly coated on a black measuring paper with an applicator having a clearance of 0.101 mm, dried at 30 ° C. for 1 hour, and then color-measured with a spectrocolorimeter (Minolta CM-1000). The thickness of each layer is indicated by the optical layer thickness.

[0031]

[Table 1] Ferric chloride content 91 g Iron oxide layer thickness 123 nm ──────────────────────────────────── ─ Titanyl sulfate amount (g) 0 2.3 6.8 45 99 113 113 ────────────────────────────────── ─── Titanium dioxide layer thickness (nm) 0 5 15 100 220 220 250 ────────────────────────────────── Total layer thickness (nm) 123 128 138 223 343 373 ───────────────────────────────────── HV / C 2.6R 5.6R 3.6R 2.0R 9.4R 8.9R 8.1 7.7 7.3 6.9 6.3 5.4 /3.3 /5.4 /5.1 /3.6 /3.0 /2.6 ───────────────── ────────────────────

[0032]

[Table 2] Amount of ferric chloride 136 g Iron oxide layer thickness 180 nm ──────────────────────────────────── ─ Titanyl sulfate amount (g) 0 2.3 6.8 45 99 113 113 ────────────────────────────────── ─── Titanium dioxide layer thickness (nm) 0 5 15 100 220 220 250 ────────────────────────────────── Total layer thickness (nm) 180 185 195 280 400 400 430 ───────────────────────────────────── HV / C 2.3R 3.1R 1.0R 5.6RP 4.3RP 3.6RP 8.0 8.2 7.8 7.2 6.9 6.6 /7.1 /7.5 /7.1 /6.5 /6.2 /5.7 ────────────────── ────────────────────

[0033]

[Table 3] Amount of ferric chloride 185 g Iron oxide layer thickness 250 nm ──────────────────────────────────── ─ Titanyl sulfate amount (g) 0 2.3 6.8 45 99 113 113 ────────────────────────────────── ─── Titanium dioxide layer thickness (nm) 0 5 15 100 220 220 250 ────────────────────────────────── Total layer thickness (nm) 250 255 265 350 350 470 500 ───────────────────────────────────── HV / C 2.6R 2.8R 9.8RP 5.0RP 3.2RP 2.2RP 8.6 8.2 6.5 6.1 5.2 4.4 /7.0 /7.3 /7.7 /7.5 /6.0 /3.6 ────────────────── ────────────────────

[0034]

[Table 4] Ferric chloride amount 279 g Iron oxide layer thickness 316 nm ──────────────────────────────────── ─ Titanyl sulfate amount (g) 0 2.3 6.8 45 99 113 113 ────────────────────────────────── ─── Titanium dioxide layer thickness (nm) 0 5 15 100 220 220 250 ────────────────────────────────── ──Total layer thickness (nm) 316 321 331 416 536 566 ───────────────────────────────────── HV / C 3.5R 4.4R 2.2RP 7.8RP 6.3RP 6.1RP 5.8 7.6 6.0 5.8 4.8 3.9 /6.6 /7.0 /7.1 /7.0 /5.3 /2.4 ────────────────── ────────────────────

[0035]

[Table 5] Ferric chloride amount 279 g Iron oxide layer thickness 377 nm ──────────────────────────────────── ─ Titanyl sulfate amount (g) 0 2.3 6.8 45 99 113 113 ────────────────────────────────── ─── Titanium dioxide layer thickness (nm) 0 5 15 100 220 220 250 ────────────────────────────────── ── Total layer thickness (nm) 377 382 392 477 597 627 ───────────────────────────────────── HV / C 4.3R 8.4R 7.0R 6.3RP 5.2RP 3.1R 5.6 4.8 4.3 3.8 3.1 2.9 /6.8 /3.6 /3.6 /2.8 /2.1 /1.6 ────────────────── ────────────────────

As can be seen from Tables 1-5, the iron oxide layer is 18
If it is less than 0 nm, a sufficient red color cannot be obtained, and 32
When it exceeds 0 nm, the saturation is remarkably reduced, or a brownish color tone peculiar to iron oxide is obtained. Further, if the layer thickness of titanium dioxide is less than 15 nm, the color tone of iron oxide cannot be adjusted, resulting in a brownish color, and if it exceeds 220 nm, the saturation decreases and the color tone becomes blurred. .
On the other hand, when the iron oxide layer has a thickness of 180 to 320 nm and the titanium dioxide layer has a thickness of 15 to 220 nm, an extremely sharp and red-purple to red-green color tone different from the color tone of brown red iron oxide is obtained. Was obtained.

When an attempt is made to obtain reddish purple to reddish green by coating aluminum oxide instead of titanium dioxide, for example, 9RP obtained when the iron oxide layer thickness is 250 nm and the titanium dioxide layer thickness is 15 nm in Table 3 above. The front and rear hues may be barely obtained by coating the layer thickness of aluminum oxide to a very large thickness of 250 nm as shown in Table 6 below, but particle aggregation is likely to occur. In addition, when the color tone of purple is further increased, for example, when the color tone of purple is stronger than 8RP, it is necessary to further increase the layer thickness of aluminum oxide, and as a result, the lightness and the saturation are remarkably increased. As a result, the desired color tone cannot be obtained as a result.
If, on the contrary, the layer thickness of aluminum oxide is made thinner in order to improve the brightness and saturation, it is far from the hues of reddish purple to reddish green as in the present invention, and the desired color tone cannot be obtained. .

[0038]

[Table 6] Iron oxide layer thickness 250nm ───────────────────────────────────── Titanium dioxide layer thickness ( nm) 15-──────────────────────────────────── Aluminum oxide layer thickness (nm) -250 ─ ─────────────────────────────────── Total layer thickness (nm) 265 500 ──────── ───────────────────────────── HV / C 9.8RP 9.3RP 6.5 / 7.7 4.4 / 8.5 ───────── ────────────────────────────

As described above, in the red pigment according to the present invention, reddish brown iron oxide-coated plate-like particles are coated with colorless or white titanium dioxide, and their layer thickness is controlled to obtain a very sharp red pigment. A purple to red-green color tone can be obtained.

Example 1 100 g of commercially available muscovite was dispersed in 500 ml of water to obtain 90
3000 ml of 10 wt% ferric chloride (hexahydrate) was added at a rate of 5 ml / min while heating to ℃ and stirring. At this time, 0.5N sodium hydroxide aqueous solution is added at the same time to maintain the pH at 4.5 to 5.0 until the reaction is completed. And
The product was filtered, dried and calcined at 500 ° C. for 2 hours to obtain 176 g of iron oxide-coated mica. Next, 100 g of the obtained iron oxide-coated mica was dispersed in 1000 ml of water in which 12 g of titanyl sulfate (dihydrate) was dissolved, and this was heated, stirred in the boiling state for 4 hours, washed with water, filtered and dried. , In the atmosphere 80
Titanium dioxide coated iron oxide coated mica 117 baked at 0 ° C
g was obtained.

The obtained powder had both a blue interference color and a bright reddish purple appearance color and gloss. The iron oxide layer of this powder had an optical layer thickness of 290 nm, the titanium compound layer had an optical layer thickness of 20 nm, and the weight ratio of iron oxide was 76 when the weight of the plate-like particles was 100%. The weight ratio of the titanium compound was 4.6% by weight based on 100% by weight of the iron oxide-coated plate-like particles.

Example 2 Commercially available iron oxide coated mica (Iriodin 524 manufactured by Merck) 10
0 g was dissolved in 62 g of titanyl sulfate (dihydrate) 10
This was dispersed in 00 ml of water, heated, stirred in the boiling state for 4 hours, washed with water, filtered, dried, and calcined at 400 ° C. in the atmosphere to obtain 136 g of titanium dioxide-coated iron oxide-coated mica. The obtained powder had a green interference color and a bright red-green appearance color and gloss. The iron oxide layer of this powder has an optical layer thickness of 250 nm, the titanium compound layer has an optical layer thickness of 165 nm, and the weight ratio of iron oxide is 100% when the weight of the plate-like particles is 100%. The weight ratio of the titanium compound was 38% by weight based on 100% by weight of the iron oxide-coated plate-like particles.

Example 3 100 g of commercially available muscovite was dispersed in 500 ml of water, 20 ml of 2M titanyl sulfate was further added, and this condition was maintained for 2 hours while heating at 90 ° C. and stirring. It was washed with water, filtered, dried, and then calcined at 800 ° C. to obtain 101 g of titanium dioxide-coated mica. Next obtained titanium dioxide-coated mica 4
0 g was dispersed in 300 ml of water, and 1500 ml of 10 wt% ferric chloride (hexahydrate) was added to 5 ml with heating and stirring at 90 ° C.
It was added at a rate of every minute. At this time, 0.5N sodium hydroxide aqueous solution was simultaneously added to adjust the pH to 4.5 until the reaction was completed.
Hold at ~ 5.0. Then, after filtering and drying the product,
Iron oxide coated mica titanium 7 after firing at 500 ° C for 2 hours
7.0 g was obtained.

Further, 70 g of iron oxide-coated titanium mica obtained
Dissolved in 80 g of titanyl sulfate (dihydrate) 1000
This was dispersed in water (ml), heated, stirred in a boiling state for 4 hours, washed with water, filtered, dried, and fired at 800 ° C. in the atmosphere to obtain 100 g of titanium dioxide-coated iron oxide-coated mica titanium. The powder obtained had a green interference color and a bright red-purple to red-green appearance color and gloss.

The iron oxide layer of this powder had an optical layer thickness of 280 nm, the titanium compound layer had an optical layer thickness of 200 nm, and the weight of the iron oxide when the weight of the plate-like particles was 100%. The ratio is 112% by weight, and the weight ratio of the titanium compound is 46% by weight when the weight of the iron oxide-coated plate-like particles is 100%.
Met.

Example 4 Commercially available iron oxide coated mica (Iriodin 524 manufactured by Merck) 10
Disperse 0 g in 500 ml of water, heat to 90 ° C. and stir while stirring 3500 ml of 1.0 wt% titanium tetrachloride aqueous solution to 5 m.
l Added at a rate of 1 minute. At this time, 0.1N sodium hydroxide aqueous solution was added simultaneously to adjust the pH to 2.
It was kept at 0 to 2.5. Then, the product is washed with water, filtered,
After drying, it was baked at 900 ° C. in the atmosphere to obtain 111 g of titanium dioxide-coated iron oxide-coated mica.

The obtained powder had both a blue interference color and a bright reddish purple appearance color and gloss.
The powder had an optical layer thickness of iron oxide of 250 nm, the titanium compound layer had an optical layer thickness of 61 nm, and the weight ratio of iron oxide was 100% by weight when the weight of the plate-like particles was 100%. The weight ratio of the titanium compound was 14% by weight when the weight of the iron oxide-coated plate-like particles was 100%.

Example 5 100 g of commercially available kaolinite, ferric chloride (hexahydrate)
300 g of urea and 150 g of urea were dispersed in 1000 ml of water, heated at 90 ° C. for 4 hours and stirred, and then the product was filtered,
It was dried and then calcined at 500 ° C. for 2 hours to obtain 186 g of iron oxide-coated kaolinite. Next, 100 g of the obtained iron oxide-coated kaolinite was added to titanyl sulfate (dihydrate).
Disperse 70 g in 1000 ml of dissolved water, heat this, stir in the boiling state for 4 hours, wash with water, filter and dry,
By firing in air at 900 ° C., 126 g of titanium dioxide-coated iron oxide-coated kaolinite was obtained.

The obtained powder had a reddish purple appearance color. The iron oxide layer of this powder had an optical layer thickness of 223 nm, the titanium compound layer had an optical layer thickness of 121 nm, and the weight ratio of iron oxide was 89 when the weight of the plate-like particles was 100%. Wt%, the weight of iron oxide coated plate-like particles is 1
The weight ratio of the titanium compound when set to 00% was 28% by weight.

The material properties of the red pigments, which are the products of the present invention obtained in the above Examples 1 to 5, were tested. For comparison, the pigment properties of colored mica titanium (iron oxide-coated mica and carmine-doped mica titanium) marketed by Maryl, USA were similarly tested. The test items are appearance color tone, acid stability,
It has alkali stability, light stability, and heat stability, and the test methods and test results are shown below.

Appearance color tone: The red pigment of the present invention and 5 g of commercially available colored mica titanium are weighed in a quartz powder color tone measuring cell, sufficiently oriented, and then pressed at a constant pressure to obtain a measurement sample. Created. Next, a measurement sample was measured with a spectrophotometer (Hitachi C-20
00). The colorimetric measurement was an average of three times. Acid stability The red pigment of the present invention and 1.5 g of commercially available colored mica titanium are placed in a test tube containing 50 ml of a stopper, and 30 ml of a 2N hydrochloric acid aqueous solution is added to the test tube to disperse it. After 24 hours, the color tone after 24 hours was visually observed.

Alkali stability The red pigment of the present invention and 1.5 g of commercially available colored mica titanium were placed in a test tube containing 50 ml of a stopper, and 30 ml of a 2N aqueous sodium hydroxide solution was added thereto to disperse the pigment.
The test tube stand was stood still and the color tone after 24 hours was visually observed. Light Stability The red pigment of the present invention and 2.5 g of commercially available colored mica titanium were each molded into a square aluminum dish having a thickness of 3 mm and a side of 20 mm, and this was irradiated with a xenon lamp for 30 hours. Color tone before and after irradiation is spectrophotometer (Hitachi C-20
00) to measure the color difference from the colorimetric value before and after irradiation (△ E)
I asked.

Thermal stability: 3.0 g of the red pigment as the product of the present invention and 3.0 g of commercially available colored mica titanium were weighed in a 20 ml magnetic crucible,
It heat-processed at 400 degreeC in the atmosphere for 2 hours. The color tone before and after the treatment was measured with a spectrocolorimeter (Hitachi C-2000), and the color difference (ΔE) before and after irradiation was determined from the colorimetric value. The results of each stability test are shown in Table 8.

[0054]

[Table 7] Pigments used in Comparative Examples ───────────────────────────────── Comparative Example 1 Cloisone Rouge Flambé Mica + Fe ₂ O ₃ ───────────────────────────────── Comparative Example 2 Cloisone Red TiO ₂ + Mica + Carmin ──── ─────────────────────────────

[0055]

[Table 8] Color tone and stability test results ──────────────────────────────────── Color tone HV / C . Acid stability Alkali stability Light stability Thermal stability ──────────────────────────────────── Implementation Example 1 6.2RP 6.10 / 7.70 ◎ ◎ 0.68 0.52 2 6.3RP 7.01 / 6.45 ◎ ◎ 0.73 0.66 3 3.0RP 5.20 / 7.00 ◎ ◎ 0.71 0.43 4 7.1RP 7.33 / 6.10 ◎ ◎ 0.68 0.62 5 2.2RP 7.10 / 6.30 ◎ ◎ 0.64 0.39 ────────────────────────────── ─────── Comparative Example 1 2.8R 4.9 / 6.9 ○ ◎ 0.77 0.83 2 2.3RP 5.4 / 7.5 × × 22.1 40.3 ────────────── ─────────────────────── Evaluation criteria: ◎ No discoloration is observed. Less stable although slight discoloration is observed observed × discoloration with still good stability at high with stability ○ visually without

From the results shown in Table 8, the red pigment, which is a product of the present invention, can have any color tone from reddish purple to reddish green by changing the amount ratio of the iron oxide and / or titanium compound coating the plate-like particles. It is understood that it can be adjusted to. The chroma of the red pigment, which is the product of the present invention, is similar to or higher than that of Chloisone red of Comparative Example 2 to which an organic substance is added. It is extremely rare that inorganic pigments have a saturation comparable to that of organic pigments, and it is clear that the plate-shaped red composite material of the present invention is superior in color tone to commercially available inorganic pigments.

Further, from the results shown in Table 8, the red pigment of the present invention has a stability which is substantially the same as or higher than that of the commercially available iron oxide-coated mica of Comparative Example 1. In particular, it is superior in acid stability to commercially available iron oxide-coated mica. This is because commercially available iron oxide-coated mica dissolves iron oxide by acid, whereas the red pigment of the present invention has the particle surface completely coated with titanium dioxide having excellent acid stability. is there. In addition, the mica titanium of Comparative Example 2 to which carmine was added has a poor stability of carmine, and therefore undergoes severe fading deterioration under severe conditions.

[0058]

As described above, according to the present invention, by coating the surface of iron oxide-coated plate-like particles with a titanium compound containing titanium dioxide and controlling the layer thickness, reddish purple to reddish green color can be obtained. Has a continuous color tone with high saturation,
Moreover, a red pigment having excellent stability can be obtained.

[Brief description of drawings]

[Figure 1]

FIG. 2 is an explanatory diagram showing a color tone adjusting action of the red pigment according to the present invention.

Claims (3)

[Claims] 1. A plate-shaped particle, an iron oxide layer that covers the surface of the plate-shaped particle, and a titanium compound layer that covers the surface of the iron oxide and is composed of a titanium compound containing titanium dioxide. A red pigment having a green color tone. 2. The red pigment according to claim 1, wherein the optical layer thickness of iron oxide coating the surface of the plate-like particles is 180 to 3.
A reddish color having a thickness of 20 nm and an optical layer thickness of a titanium compound layer made of a titanium compound containing titanium dioxide that covers the iron oxide surface is 15 to 220 nm and has a reddish purple to red green color tone. Pigments. 3. The plate-shaped particles are oxidized by a deposition method from a coating bath containing a precursor of the iron oxide so that the amount of iron oxide to be coated on the plate-shaped particles is 80 to 140% by weight. Iron is coated to form iron oxide-coated plate-like particles, and the amount of titanium dioxide containing titanium dioxide to be coated is 3 to 50% by weight relative to the iron oxide-coated plate-like particles. A titanium compound is coated on the iron oxide-coated plate-like particles by a deposition method from a coating bath containing a titanium compound precursor containing titanium to form a titanium compound-coated iron oxide-coated plate-like particle, and the titanium compound-coated iron oxide coat 300 to 9 plate particles
A method for producing a red-based pigment, which has a red-purple to red-green color tone obtained by firing at 00 ° C.