JPH06184461A - Glossy pigment and its production - Google Patents

Abstract

PURPOSE:To obtain a new glossy pigment without any disadvantages of a platy crystal, inferior in orienting properties in a film or a resin due to the thick platy crystal and a low flakiness (diameter/thickness), having a great change in color tone and hardly controlling the color tone of the film or resin in a dispersing step due to easy collapsibility of the platy crystal in dispersing thereof in the film or resin and disadvantages of a scaly iron oxide of an Al solid solution having a restriction on the regulable color tone due to its red color tone even by adding other pigments thereto. CONSTITUTION:This glossy pigment is characterized by coating the surface of a scaly iron oxide with a titanic iron ore-based compound having the ilumenite structure. The titanic iron ore-based compound is preferably a substance of a single phase or a mixed phase selected from the group consisting of the titanic iron ore, geikielite and pyrophanite. The scaly iron oxide scaly is red iron oxide of an Al solid solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pigment having a luster and a method for producing the pigment, and more specifically to a pigment having a luster useful in a wide variety of fields such as paints, synthetic resins, cosmetics, inks, synthetic leathers and wallpapers, and its production. It is about law.

[0002]

2. Description of the Related Art Micaceous iron oxide (Micaceous Iron Oxide, hereinafter abbreviated as "MIO") and Al solid solution scale red iron oxide are known as pigments having iron oxide luster. MIO has a black-purple color and is said to have a strong metallic luster (see Japanese Patent Publication No. 43-12435).
However, since the plate-like crystals are thick and the plate-like ratio (diameter / thickness) is small, the orientation in the coating film or the resin is poor, and it is difficult to utilize their effective properties as a luster pigment. Further, since the plate-like crystals are easily broken when dispersed in a paint or a resin, there is a problem that the color tone of the coating film or the resin is difficult to control because of a large change in the color tone in the dispersing step. Further, Al solid solution scaly red iron oxide is a plate-shaped iron oxide having a composition of Al _x Fe _2-x O ₃ and having a strong luster and having a hematite structure, and has a stronger luster and hiding power than MIO. It is supposed to have (Japanese Patent Publication Sho 60-
(See Japanese Patent No. 8977). Since this iron oxide has a large plate-like ratio, it has good orientation in the coating film and resin, and since the plate-like crystals are hard to break when dispersed in the paint, the change in color tone during the dispersion process is small. Although it has features such as easy control of the color tone of the coating film and the resin, since the color tone is red, there is a limit to the color tone that can be adjusted by adding other pigments. Japanese Examined Patent Publication No. 61-21976 discloses a luster pigment obtained by coating the surface of Al solid solution scale-like red iron oxide particles with titanium dioxide hydrate or titanium dioxide as a pigment for improving the above-mentioned drawbacks of Al solid solution scale-like red iron oxide. Disclosure. However, the pigment
Although the color tone can be variously changed by controlling the thickness of the titanium dioxide hydrate layer or the titanium dioxide layer on the surface of the Al solid solution scale red iron oxide particles, the gloss which is an important characteristic as a luster pigment is It has a drawback that it is weak compared with that of the base pigment, Al solid solution scale red iron oxide.

Japanese Unexamined Patent Publication No. 63-317559 discloses a wide variety of pigment tones from copper to black by reducing the surface of an Al solid solution scale red iron oxide to generate a spinel phase in the surface layer of the pigment. It discloses that it is possible to adjust. However, the pigment obtained by this method has problems that the luster is weaker than that of the Al solid solution scale red iron oxide and the mechanical strength is small.

[0004]

As described above, the conventional plate-shaped or scale-shaped iron oxide pigment has poor orientation in the coating film or resin, and it is difficult to control the color tone of the coating film or resin. However, since the color tone is red, the color tone that can be adjusted is limited even if other pigments are added. Further, the color tone of the luster pigment is obtained by coating the surface of the Al solid solution scale-like red iron oxide particles with titanium dioxide hydrate or titanium dioxide, or by forming a spinel phase on the surface of the Al solid solution scale-like red iron oxide particles. However, the gloss of the pigment obtained by this treatment becomes weaker than that of the Al solid solution scale red iron oxide of the substrate, and the characteristics that Al solid solution scale red iron oxide has as a gloss pigment It wasn't what made use of.

Therefore, an object of the present invention is to provide a luster pigment which does not have the drawbacks of the conventional plate-shaped or scale-shaped iron oxide pigment, and a method for producing the same.

[0006]

The inventors of the present invention have conducted extensive studies to develop a new luster pigment that does not have the drawbacks of conventional luster pigments. As a result, the surface of scaly iron oxide particles was coated with a ilmenite-based compound. The present invention has been completed by discovering that plate-like pigments have characteristics that conventional pigments do not have.

That is, the present invention provides a lustrous pigment characterized in that the surface of scaly iron oxide is coated with a ilmenite compound having an ilmenite structure. In the present invention, scaly iron oxide particle surfaces ilmenite compound coating the preferably ilmenite (FeTiO _3), gate key light (MgTiO ₃₎ and Pyro files Knight (Mn
TiO ₃ ), and binary and ternary solid solutions containing these minerals as end components can be used as well. As the scale-like iron oxide, Al solid solution scale-like red iron oxide is preferably used. The thickness of the crystal obtained by the ultrathin section method is preferably 1 μm or less, more preferably 0.1 to 0.7 μm. The particle size is preferably 1 to 50 μm.

The ilmenite-based compound-coated scale-like iron oxide pigment according to the present invention has the following features.

A) It is non-toxic because the surface of the iron-aluminum oxide is coated with a ilmenite-based compound consisting of titanium oxide and at least one of iron oxide, manganese oxide and magnesium oxide.

B) Since the synthetic product is used as the base pigment, the quality of the product is stable.

C) Since the ilmenite-based compound exhibits a brown or black color, the color tone of the pigment can be widely varied depending on the coating amount. For example, in the case of Al solid solution scale red iron oxide, red to black. Can be changed up to.

D) It has a larger hiding power than Al solid solution scale red iron oxide.

E) It has a strong luster comparable to that of Al solid solution scale red iron oxide.

F) Since the plate crystals are less likely to break when dispersed in a paint or resin, the change in color tone during the dispersing step is small and the color tone of the coating film or resin is easy to control.

The Al solid solution scaly red iron oxide preferably used as the substrate of the pigment of the present invention is, for example, Japanese Patent Publication No. 60-
It is a luster pigment disclosed in Japanese Patent No. 8977, and is typically manufactured under the following conditions.

It can be produced by hydrothermally treating a colloidal precipitate of iron oxyhydroxide or ferric iron in an aqueous solution of aluminate. Specifically, for example, α-iron oxyhydroxide (α-FeOOH) is added to alumina. After being dispersed in an aqueous solution of sodium acid and subjected to hydrothermal treatment at a temperature of 250 ° C. or higher using an autoclave, α-iron oxyhydroxide is 2α-
Decomposes as FeOOH → α-Fe ₂ O ₃ + H ₂ O, MI
O (α-Fe ₂ O ₃ ) crystallizes out, but at this time, aluminum ions in the solution are taken into the crystal lattice, and Al solid solution scale red iron oxide (α-AlxFe ₂ -xO ₃ ) is produced. .

The aqueous aluminate solution used as the hydrothermal treatment mother liquor in the above method is usually prepared by dissolving the aluminate in water or an aqueous alkali solution.
It can also be adjusted from other aluminum compounds. Specifically, (1) after dissolving an aluminum compound, such as aluminum chloride, aluminum sulfate, and aluminum nitrate, whose aqueous solution shows acidity, in water, alkali is added until the pH of the aqueous solution becomes 10 or more. To use. That is, aluminum is said to exist as an aluminate ion in an aqueous solution having a pH of 10 or more (G. Charlow, Kozo Sone, Motoharu Tanaka: Qualitative Analytical Chemistry, Kyoritsu Publishing Co., Ltd., 1974). The solution is now conditioned. (2) Metallic aluminum and alumina are used by dissolving them in a strong acid or a strong alkali. That is, when it is dissolved in a strong acid, the same operation as in the above (1) is performed, and when it is dissolved in a strong alkali, the solution is left as it is and the concentration is adjusted appropriately before use.

The concentration of Al ₂ O ₃ in the aqueous aluminate solution is 10 to 350 g / liter, preferably 20 to 200.
It is in the range of g / liter. That is, when the concentration is lower than 10 g / liter, it is difficult to obtain a product having a strong gloss, and when it exceeds 350 g / liter, the storage stability of the solution is poor, which is not practical.

A in the aluminate solution aqueous solution
The relative proportion of l ₂ O ₃ concentration and alkali concentration is also important. That is, if the alkali concentration is too high with respect to the Al ₂ O ₃ concentration, the solid solution rate of aluminum in the MIO crystal decreases, and the crystal thickness increases, which is not preferable because the properties of the product approach MIO. If the alkali concentration is too low with respect to the Al ₂ O ₃ concentration, the storage stability of the solution deteriorates, which is not practical. N for Al ₂ O ₃ concentration (g / liter) when sodium aluminate is used as an aluminate
As for the ratio of aOH concentration (g / liter), when Al ₂ O ₃ is 1, NaOH is about 0.8 to 1.8.

Furthermore, when iron oxyhydroxide is used as the iron raw material, the slurry concentration during hydrothermal treatment varies depending on the type of iron oxyhydroxide and the size of the particles, etc. and is not as uniform as the case may be, with a high value of 500 g / liter. Although the treatment can be carried out even with a concentration, it is in the range of 200 g / liter or less in most cases, and particularly 150 g / liter or less is suitable for obtaining a large product having a uniform particle size distribution.

Other factors affecting the particle system and thickness of the product include the rate of temperature rise and the state of stirring during the hydrothermal treatment, and among these factors, the rate of temperature rise has a large influence on the thickness of the product. ing. That is, in order to obtain a thin product, it is necessary to increase the temperature rising rate, and to obtain an Al solid solution scale red iron oxide having a yellow-red color and a thickness of 0.15 μm or less. Then, the rate of temperature increase in the temperature range of 250 ° C. or higher is preferably 50 ° C./Hr or higher.

The purity of the Al solid solution scale red iron oxide used as the base pigment may be 95% or more.
There is no particular problem even if Mn, Ti, Zn, Si, Co, Cr, Ni, Mg, Ca, Si and the like are contained as impurities in the Al solid solution scale red iron oxide.

Further, the base pigment is not limited to Al solid solution flaky red iron oxide, and is, for example, Japanese Patent Publication No. 43-12435, Japanese Patent Publication No. 55-104923.
Further, scaly iron oxide having a size of 1 μm or less produced by another method such as JP-A-63-112663 can be used. The coating treatment of the ilmenite-based compound on the surface of the flaky iron oxide particles can be performed by the following method.

That is, in the coating treatment with ilmenite, a water-soluble titanium salt is added to an aqueous slurry of scaly iron oxide, and this is hydrolyzed to hydrate titanium dioxide hydrate on the surface of the scaly luster pigment particles. Is deposited, filtered, washed, and then fired in an inert gas atmosphere. Add water-soluble iron salt together with water-soluble titanium salt,
After hydrolyzing these to deposit titanium dioxide hydrate and iron oxide hydrate on the surface of the scaly luster pigment particles,
Although the coating treatment with ilmenite can be performed by a method of firing in an inert gas atmosphere after filtration and washing, the coating treatment is possible without particularly adding the water-soluble iron salt together with the water-soluble titanium salt. is there. That is, by firing in an inert gas atmosphere, ferric iron of the base flaky iron oxide is reduced to ferrous iron, and this ferrous iron reacts with titanium oxide present on the surface of the particles to form ilmenite. To generate.

In the coating treatment with Gakey light, a water-soluble titanium salt is added to an aqueous slurry of scaly iron oxide, and this is hydrolyzed to form titanium dioxide hydrate on the surface of the scaly luster pigment particles. After deposition, a water-soluble magnesium salt is added to the slurry, the liquid temperature of the slurry is raised to the boiling point, and then filtration, washing and firing are performed.

The coating treatment with pyrophanite is carried out by adding a water-soluble titanium salt and a water-soluble manganese salt to an aqueous slurry of scaly iron oxide, and hydrolyzing this to oxidize the surface of the scaly luster pigment particles. After depositing titanium hydrate and manganese oxide hydrate, filtration, washing, and firing in an inert gas atmosphere are carried out.

The coating treatment with Gakey light and ilmenite-based solid solution is carried out by adding a water-soluble titanium salt and a water-soluble iron salt to an aqueous slurry of scaly iron oxide, and hydrolyzing this to add the scaly luster pigment. After depositing titanium dioxide hydrate and iron oxide hydrate on the surface of the particles, after adding a water-soluble magnesium salt to the slurry, the liquid temperature of the slurry is raised to the boiling point, then, after filtration and washing, The firing is performed in an inert gas atmosphere.

The coating treatment with pyrofanite and ilmenite-based solid solution is carried out by adding a water-soluble titanium salt, a water-soluble iron salt and a water-soluble manganese salt to an aqueous slurry of flaky iron oxide, and hydrolyzing the resulting solution. It is carried out by depositing titanium dioxide hydrate, iron oxide hydrate and manganese oxide hydrate on the surface of scaly luster pigment particles, filtering and washing, and then firing in an inert gas atmosphere.

As the water-soluble titanium salt, titanyl sulfate, titanium sulfate, titanium tetrachloride, etc. can be used, and as the water-soluble iron salt, ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride. , Ferrous nitrate, ferric nitrate, etc. can be used. Further, magnesium hydroxide is preferably used as the water-soluble magnesium salt, and as the water-soluble manganese salt, manganese sulfate, manganese sulfate, manganese chloride,
Manganese chloride, manganese nitrate, manganese nitrate, etc. are used.

The firing temperature is preferably in the range of 500 to 1200 ° C. That is, if the firing temperature is lower than 500 ° C., the reaction rate is slow and long heating is required, which is not practical, and particles having a firing temperature higher than 1200 ° C. are sintered and the dispersibility deteriorates. Therefore, it is not preferable.

When coating with a ilmenite-based compound containing ilmenite or pyrophanite, it is necessary to fire in a region where Fe ²⁺ and Mn ²⁺ are stable during firing, that is, in an inert gas atmosphere. .

It should be noted that even if Ni or Co is contained as a constituent component of the ilmenite-based compound, it does not matter at all, a part of Ti ⁴⁺ is changed to Ti ³⁺ depending on the firing conditions, or the base Al solid solution scale is used. Even if a part of the red iron oxide is changed to the spinel phase, if the ilmenite-based compound is formed on the surface of the luster pigment particles, a pigment with strong luster can be obtained, so there is no particular problem.

The treatment can be performed by using a reducing gas instead of the inert gas. However, in order to obtain a pigment having the same color tone with good reproducibility by this method, it is necessary to strictly adjust the treatment conditions. .

The present invention will be described in more detail with reference to the following examples. The following examples are given for illustrative purposes only and the scope of the invention is not limited thereby.

[0035]

【Example】

Example 1. 110 g of commercially available yellow iron oxide (α-FeOOH: Turox LL-XLO) as Al ₂ O ₃ is 50 g /
Liter, dispersed in 1000 ml of 65 g / liter sodium aluminate aqueous solution as NaOH, and then charged in an autoclave lined with nickel.
The temperature was raised to 300 ° C. in 1 hour while stirring at 50 rpm, and then the temperature was maintained for 20 minutes.

After allowing to cool, the contents were taken out of the autoclave, washed with water until the electric conductivity of the filtrate became 100 μS / cm or less, and then dried.

The color tone of this product was red and had a strong luster, the size in the plate-like direction was 3 to 25 μm, and the crystal thickness determined by the ultrathin section method was about 0.2 μm.

50 g of the above iron oxide was used as TiO ₂ for 2.5
g, a titanyl sulfate aqueous solution containing 12 g of H ₂ SO ₄ 1
After dispersing in 000 ml, the temperature was raised to the boiling point while stirring at 300 rpm, and the temperature was maintained for 2 hours. 1000 ml of warm water was added to the slurry and the temperature was kept at the boiling point for 1 hour. After cooling, the filtrate was washed with water until the electric conductivity of the filtrate became 100 μS / cm or less, and then dried. When heat-treated at 950 ° C. for 1 hour in a nitrogen gas atmosphere, a highly glossy pigment having a black color tone was obtained. X-ray powder diffraction identified ilmenite and Al solid solution red iron oxide having a hematite structure.

Example 2. After 85 g of Al solid solution scale red iron oxide synthesized under the same conditions as in Example 1 was dispersed in a sulfuric acid acid solution containing 4.0 g of TiO ₂ and 3.9 g of MnO, 40 g / liter of hydroxylation was obtained. An aqueous solution of sodium was added dropwise to adjust the pH of the slurry to 9.0. The filtrate was washed with water until the electric conductivity was 100 μS / cm or less, and then dried. 600 ℃ in nitrogen gas atmosphere
When subjected to a heat treatment for 0.5 hour, a highly glossy pigment having a reddish brown color tone was obtained. X-ray powder diffraction identified Al solid solution red iron oxide having pyrophanite and hematite structure.

Example 3. 25 g of Al solid solution scale red iron oxide synthesized under the same conditions as in Example 1 was dispersed in 1000 ml of an aqueous titanyl sulfate solution containing 1.4 g of TiO _{2 and} 13 g of H ₂ SO ₄ , and then 300 r
After the temperature was raised to the boiling point while stirring at pm, the temperature was raised to 2
Held for hours. 1000 ml of warm water was added to the slurry and the temperature was kept at the boiling point for 1 hour. After allowing to cool, the filtrate was washed with water until the electric conductivity was 100 μS / cm or less.
After being dispersed in a magnesium hydroxide aqueous solution containing 1.3 g of MgO, the liquid temperature of the slurry was raised to the boiling point while stirring at 300 rpm, and the temperature was maintained for 2 hours. The filtrate was washed with water until the electric conductivity was 100 μS / cm or less, and then dried. When heat-treated at 700 ° C. for 1 hour in air, a highly glossy pigment having a brown color tone was obtained. X-ray powder diffraction identified Alky solid solution red iron oxide having Gehkylite and hematite structure.

Example 4. 40 g of Al solid solution scaly red iron oxide synthesized under the same conditions as in Example 1 was 2.0 g as TiO ₂ , 0.9 g as MnO and 0.9 as FeO.
After being dispersed in a sulfuric acid acidic solution containing g, 40 g / liter of an aqueous sodium hydroxide solution was added dropwise to adjust the pH of the slurry to 7.5. The electric conductivity of the filtrate is 100μ
It was washed with water until S / cm or less and then dried. When heat treatment was performed at 900 ° C. for 1 hour in a nitrogen gas atmosphere, a highly glossy pigment having a blackish brown color tone was obtained.
X-ray powder diffraction identified ilmenite-based compounds having an ilmenite structure and Al solid solution red iron oxide having a hematite structure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruyoshi Okazaki 25 Titan Kogyo Co., Ltd., 1978 Kogushi, Ube, Yamaguchi Prefecture

Claims (8)

[Claims] 1. A luster pigment characterized in that the surface of scaly iron oxide is coated with a ilmenite compound having an ilmenite structure. 2. The ilmenite-based compound is selected from the group consisting of ilmenite, gerkylite and pyrophanite, and a solid solution of two and three components having the above components as end components. 1. The bright pigment according to 1. 3. The luster pigment according to claim 1, wherein the scaly iron oxide is Al solid solution scaly red iron oxide. 4. A water-soluble titanium salt is added to an aqueous slurry of flaky iron oxide, which is hydrolyzed to deposit titanium dioxide hydrate on the surface of the flaky pigment particles and then filtered. The method for producing a luster pigment according to claim 1, characterized in that after the washing, the pigment is baked in an inert gas atmosphere. 5. A water-soluble titanium salt is added to an aqueous slurry of scale-like iron oxide, which is hydrolyzed to deposit titanium dioxide hydrate on the surface of the scale-like luster pigment particles, 2. The method for producing a luster pigment according to claim 1, wherein the pigment is dispersed in an aqueous magnesium salt solution, the temperature of the slurry is raised to the boiling point, and then the slurry is filtered, washed and calcined. 6. A water-soluble titanium oxide and water-soluble manganese salt is added to an aqueous slurry of scaly iron oxide, which is hydrolyzed to hydrate titanium dioxide and oxidize on the surface of the scaly luster pigment particles. The method for producing a luster pigment according to claim 1, wherein the manganese hydrate is deposited, filtered, washed, and then fired in an inert gas atmosphere. 7. A water-soluble slurry of scaly iron oxide, to which a water-soluble titanium salt and a water-soluble manganese salt are added, which are hydrolyzed to hydrate the titanium dioxide hydrate and oxidize on the surface of the scaly luster pigment particles. After depositing a manganese hydrate, the pigment is dispersed in an aqueous magnesium salt solution, the temperature of the slurry is raised to the boiling point, then filtered, washed, and then fired in an inert gas atmosphere. Claim 1
A method for producing the luster pigment described. 8. The scaly red iron oxide is Al solid solution scaly red iron oxide having a crystal thickness of 1 μm or less as determined by an ultrathin section method. The method for producing a lustrous pigment according to item 1.