JP2003119408A - Color-controllable rare earth phosphate-based pigment and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color-changeable rare earth phosphate-based pigment and to provide a method for producing the same. SOLUTION: A rare earth metal salt or oxide is uniformly mixed with at least one kind of a salt or an oxide of an element selected form alkali metals, alkaline earth metals, transition metals, rare earth metals different from the base material and another element to be a cation and ammonium phosphate, and fired in an oxidizing atmosphere at 600 deg.C-1,500 deg.C to synthesize a complex phosphate of the rare earth metal with at least one kind of the element selected from the alkali metals, alkaline earth metals, transition metals, the rare earth metals different from the base material and another metal to be a cation, which is made into a solid solution or a composite. The color of the rear earth phosphate-based pigment can be controlled by the kind and/or the amount of the metal phosphate to be made into the composite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pigment based on a rare earth element phosphate and a complex with a cation different from the rare earth based on the phosphate, and a method for producing the same.

[0002]

2. Description of the Related Art Pigments currently manufactured on an industrial scale as coloring pigments for various substances such as ceramics, plastics and paints include cadmium red, red iron oxide, yellow lead, cobalt green, ultramarine blue, dark blue and cobalt. Blue has been known since ancient times.

However, because these pigments contain metals that are extremely harmful to the human body, especially cadmium, lead, chromium and cobalt, their use is becoming more and more strictly regulated, and indeed many. The problem in the country is that they are banned by law because of their extremely high toxicity. Therefore, there is a demand for materials that can replace them.

As one of the solutions to the above-mentioned problem,
Pigments based on the rare earth element sesquisulfide and calcium, lanthanum, and tantalum complex perovskite oxynitrides have been developed, but in order to obtain highly pure pigments,
The former has a major drawback that hydrogen sulfide must be used during synthesis and the latter must use combustible and toxic gas such as ammonia gas.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems and provide a novel inorganic pigment having high safety and a method for producing the same using a highly safe compound. .

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors extensively studied reaction raw materials and synthetic methods,
After carefully examining the conditions, Sc, Y, and atomic number 5
A salt or oxide of a rare earth metal of 7 to 71, and at least one salt selected from an alkali metal, an alkaline earth metal, a transition metal, a rare earth metal different from the matrix, and other elements capable of forming a cation, or An oxide and an ammonium salt of phosphoric acid are mixed, and a method for producing a rare earth complex phosphate, which is characterized by firing in an oxidizing atmosphere, is found, whereby a new pigment based on a rare earth phosphate is obtained. I got it.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The rare earth complex phosphate particles of the present invention are LnPO ₄ : M or LnP ₂ O ₇ : M (where Ln is an element selected from Sc, Y, and rare earth elements having atomic numbers 57 to 71, and M is an alkali). At least one element selected from a metal, an alkaline earth metal, a transition metal, a rare earth metal different from Ln, and another element that can be a cation) is a pigment particle characterized by being represented by a composition formula. .

The method for producing pigment particles of the present invention is selected from oxides or salts of rare earth metals, alkali metals, alkaline earth metals, transition metals, rare earth metals different from the matrix, and other elements capable of forming cations. Characterized in that it is mixed with at least one salt or oxide to be treated and ammonium salt of phosphoric acid, and calcined in an oxidizing atmosphere (for example, in air). The rare earth-based phosphate composite particles can be obtained by an extremely simple method without using a high reaction gas.

The rare earth sources used in the present invention include scandium, yttrium, and lanthanum.
Oxides, hydroxides, nitrates, chlorides, acetates, citrates, sulfates, carbonates, oxalates, oxycarbonates of rare earth elements having an atomic number of 57 to 71 including cerium,
Although oxysulfates, ammonium sulfates, ammonium nitrates and the like can be used, preferably sulfates which are highly reactive and in which a solid-phase reaction easily proceeds, or rare earth phosphates themselves are used.

In the present invention, the cation source to be complexed with the rare earth is at least one selected from alkali metals, alkaline earth metals, transition metals, rare earth metals different from Ln, and other elements capable of forming cations. Elemental oxides, hydroxides, nitrates, chlorides, acetates,
Citrate, sulfate, carbonate, oxalate, oxycarbonate, oxysulfate, ammonium sulfate, ammonium nitrate and the like can be used, but phosphate itself is preferably used.

The phosphorus source used in the present invention is not particularly limited as long as it is a substance containing phosphorus as a constituent source, regardless of whether it is an inorganic substance or an organic substance. At least one selected from ammonium phosphate, diammonium phosphate, and triammonium phosphate is preferably used because of its high reactivity.

In relation to the preceding paragraph, when a phosphate is used as a starting material for rare earth and a cation species to be complexed, particularly when a reaction proceeds without adding a phosphorus source, a phosphorus source is not added. However, in such a case, a phosphoric acid source is preferably used in order to accelerate the reaction.

The above-mentioned raw materials are mechanically mixed by a mortar or a ball mill. The obtained mixed powder remains powdery, or is pelletized by pressure molding,
Heat treatment is performed in an oxidizing gas. As the oxidizing gas at this time, oxygen, air, a mixed gas thereof, or the like can be used, and it is not particularly limited, but air that does not cost much is preferably used.

The temperature of the heat treatment is 600 to 15
It can be carried out at any temperature in the range of 00 ° C,
In order to increase the reaction rate, it is desirable to carry out at 900 to 1000 ° C. Further, at 600 ° C. or lower, the production rate of the rare earth-based phosphate is significantly reduced due to the decrease in the reaction rate,
On the other hand, at 1500 ° C. or higher, decomposition of the produced rare earth phosphate occurs.

Further, the heat treatment time is set to 1 to 50 hours, preferably 5 to 15 hours. It can be said that it is desirable to set the upper limit and the lower limit of the heat treatment temperature and time in consideration of the progress of the solid-phase reaction and the energy consumption required for the reaction.

The rare earth phosphate particles of the present invention are capable of exhibiting a very wide range of colors, particularly depending on the rare earth elements forming a part of their composition and the different cations to be complexed. . This shows that those chromaticity coordinates can be controlled in an extremely wide range. As an example, cerium phosphate (CeP
Examples of color change in the case of O ₄ ) are described below, but the present invention is not limited thereto. -When alkaline earth metals such as calcium, strontium and barium are compounded, the white color of the cerium phosphate matrix changes from green to green. -It turns yellow when bismuth and / or nickel is combined.・ When yttrium is compounded, it changes to beige. -It turns brown when iron is compounded.・ When copper is compounded, it changes to blue-green.・ It becomes light purple when Neodymium is compounded.・ Compounding europium turns pink.

The ratio of the cations to be complexed in the present invention may be any composition as long as it produces a color, and is not particularly limited, but a composition in which M is 20 to 60 mol% relative to the rare earth Ln is used. It is preferably used because the color is often expressed.

The rare earth phosphate thus obtained may be washed if necessary. The washing medium at this time may be any medium as long as it dissolves impurities, and is not particularly limited, but water is preferably inexpensive and easy to use.

The washing method in the preceding paragraph may be repeated centrifugation or decantation and filtration, or a fine powder washing apparatus using a ceramic filter or an ultrafiltration membrane. The washed particles are dried by air drying at room temperature or by heat drying using an oven or the like. At this time, a vacuum dryer, a freeze dryer, a spray dryer or the like may be used, and is not particularly limited, but drying by a rotary evaporator that can be easily and quickly evaporated, heat drying using an oven, or the like, A combination of is preferably used.

In this way, it is possible to obtain a novel colored pigment which is based on a rare earth phosphate and whose color can be controlled by the cation species to be complexed.

Furthermore, the rare earth phosphate-based pigment particles of the present invention have very good tinting strength and very good hiding power, so that they are suitable for plastics, paints, varnishes, rubbers, ceramics, glass, paper, Ink, cosmetics,
It can be used very suitably for coloring many substances such as dyes.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In these examples, CIE 19 is the color space recommended by the CIE (International Commission on Illumination) in 1976.
The color is evaluated by a 76 (L ^* a ^* b ^* ) color system. This color specification method is based on JIS according to Japanese Industrial Standards.
Z 8729.

In the L ^* a ^* b ^* colorimetric method of the previous section, L ^*
Gives a measure of the reflectance (bright / dark) and takes values from 100 (white) to 0 (black). On the other hand, a ^* and b ^* are values of color tendency, and + a ^* = red and −a ^* =, respectively.
Green, + b ^* = yellow, and -b ^* = blue. That is, L ^*
Represents a change from black to white, a ^* represents a change from green to red, and b ^* represents a change from yellow to blue.

[0024]

Example 1 5.54 g of cerium (III) sulfate octahydrate, 1.04 g of calcium carbonate and 3.42 g of ammonium hydrogen phosphate were placed in a mortar and the whole was pulverized to obtain a homogeneous mixture. At this time, the Ce / Ca molar ratio is 1.5.
Met. Next, this homogeneous mixture was calcined as a powder in an air stream at 900 ° C. for 24 hours. The powder obtained was a CePO ₄ : Ca solid solution by powder X-ray diffraction, and had L ^*
= 71.2, a ^* =-8.37, b ^* = 15.6, which was a green powder having chromaticity coordinates.

(Example 2) 5.22 g of cerium (III) sulfate octahydrate, 1.55 g of strontium chloride and 3.43 g of ammonium hydrogen phosphate were placed in a mortar and the whole was ground to obtain a homogeneous mixture. At this time, the Ce / Sr molar ratio was 1.5. Next, this homogeneous mixture was calcined as a powder in an air stream at 900 ° C. for 24 hours. The powder obtained was a CePO ₄ : Sr solid solution by powder X-ray diffraction, and had L ^* = 76.6, a ^* = − 8.37, b ^* = 15.
It was a green powder having a chromaticity coordinate of 6.

(Example 3) Cerium (III) sulfate octahydrate
5.24 g, nickel sulfate 1.52 g, hydrogen phosphate
3.24 g of ammonium monoxide is placed in a mortar, and the whole is ground and smoothed.
Quality mixture. At this time, the Ce / Ni molar ratio is 1.5.
Met. This homogeneous mixture is then left as a powder in air.
It was baked at 900 ° C. for 24 hours under circulation. The powder obtained is
From powder X-ray diffraction to CePO_Four: Ni solid solution, L^*
= 91.3, a^*= -2.63, b ^*= 16.0 chromaticity
It was a yellow powder with coordinates.

(Example 4) 6.22 g of cerium (III) sulfate octahydrate, 12.1 g of neodymium acetate monohydrate, and 11.7 g of ammonium hydrogen phosphate were placed in a mortar, and the whole was crushed to obtain a homogeneous mixture. And At this time, the Ce / Nd molar ratio was 1.5. Next, this homogeneous mixture was calcined as a powder in an air stream at 900 ° C. for 24 hours. The powder obtained was a CePO ₄ : Nd solid solution by powder X-ray diffraction, and L ^* = 89.0, a ^* = 6.65, b ^* = − 3.3.
It was a purple powder having a chromaticity coordinate of 5.

Example 5 5.10 g of cerium (III) sulfate octahydrate, 1.76 g of europium acetate monohydrate,
3.15 g of ammonium hydrogen phosphate was placed in a mortar and the whole was crushed into a homogeneous mixture. At this time, the Ce / Eu molar ratio was 1.5. Next, this homogeneous mixture was calcined as a powder in an air stream at 900 ° C. for 24 hours. The powder obtained was a CePO ₄ : Eu solid solution by powder X-ray diffraction, and L ^* = 91.8, a ^* = 4.47, b ^* = −.
It was a pale red powder with a chromaticity coordinate of 0.16.

(Example 6) 5.35 g of cerium (III) sulfate octahydrate, 1.35 g of copper chloride and 3.30 g of ammonium hydrogen phosphate were placed in a mortar and the whole was ground to obtain a homogeneous mixture. At this time, the Ce / Cu molar ratio was 1.5. Next, this homogeneous mixture was calcined as a powder in an air stream at 900 ° C. for 24 hours. The obtained powder was CePO ₄ : Cu solid solution by powder X-ray diffraction, and L ^* = 8.
It was a pale blue-green powder having chromaticity coordinates of 7.5, a ^* =-9.66, b ^* = 1.71.

[0030]

According to the present invention, a salt or oxide of Sc, Y, and a rare earth metal having an atomic number of 57 to 71, an alkali metal, an alkaline earth metal, a transition metal, a rare earth metal different from the matrix, and At least one salt or oxide selected from other elements capable of forming cations and an ammonium salt of phosphoric acid are uniformly mixed and simply baked at 600 ° C to 1500 ° C in an oxidizing atmosphere. In this way, it is possible to obtain a novel inorganic pigment having high safety and a production method thereof using a compound having high safety. Furthermore, in the rare earth phosphate-based pigment of the present invention, the color can be controlled by the type of cation to be complexed.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ginya Adachi             Takigahana, Mikage, Mikage Town, Higashinada-ku, Kobe City, Hyogo Prefecture             No. 1345-9 (72) Inventor Nobunato Imanaka             4-1-1 Higashi Uneno, Kawanishi City, Hyogo Prefecture (72) Inventor Toshiyuki Masui             1-2 Aoyamadai, Suita City, Osaka Prefecture C20-103             issue F-term (reference) 4J037 AA04 CA09 CA10 CA11 CA22                       DD20 EE25 EE44 EE47 FF03                       FF29

Claims (4)

[Claims] 1. LnPO ₄ : M or LnP ₂ O ₇ :
M (where Ln is an element selected from Sc, Y, and rare earth elements with atomic numbers 57 to 71, M can be an alkali metal, an alkaline earth metal, a transition metal, a rare earth metal different from Ln, and a cation. Pigment particles represented by a composition formula of at least one element selected from other elements). 2. The pigment particles according to claim 1, wherein the color can be controlled by changing the type of M and / or the amount of complexation. 3. The pigment particle according to claim 1, wherein Ln is Ce. 4. Sc, Y, and atomic numbers 57 to 71.
Up to rare earth metal salts or oxides with alkali metals,
At least one salt or oxide selected from an alkaline earth metal, a transition metal, a rare earth metal different from the matrix, and other elements capable of forming a cation, and an ammonium salt of phosphoric acid are uniformly mixed and oxidized. 60 in a sex atmosphere
By firing at 0 ° C. to 1500 ° C., at least one selected from rare earth metals, alkali metals, alkaline earth metals, transition metals, rare earth metals different from the matrix, and other elements that can be cations. 4. A complex phosphate with an element, characterized in that
The method for producing the pigment particles according to item 1.