JPH0859218A - Method for producing inorganic pigment from iron phosphate and / or phosphate sludge - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for producing an inorganic pigment. [Structure] An aqueous suspension having a pH of less than 7 containing at least 50% by weight of at least one kind of phosphate sludge generated in the phosphate chemical conversion treatment of iron phosphate and a metal material and iron are placed in a closed pressure vessel. After filling and heat and pressure treatment, the product containing the precipitate is filtered and the precipitate is collected,
A method for producing an inorganic pigment from iron phosphate and / or phosphate sludge, which comprises washing with water and drying to produce the inorganic pigment. [Effect] A new inorganic pigment of green to black green is obtained, and the phosphate sludge can be effectively used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an inorganic pigment, more specifically, a novel inorganic pigment produced from a phosphate chemical conversion sludge generated in a phosphoric acid conversion treatment of iron phosphate and / or a metal material. Method, and to the reuse of phosphate sludge.

[0002]

2. Description of the Related Art Generally, phosphate pigments such as zinc phosphate and iron phosphate pigments are excellent in anticorrosive properties, and therefore various pigments such as anticorrosive primers, intermediate coatings and undercoating pigments. Is used for. As a method for producing a zinc phosphate pigment, JP-A-49-26291 discloses that a phosphate treatment solution containing zinc ions is allowed to act on an iron material to form a precipitate containing zinc phosphate as a main component. ing. In this production process, the precipitates are colloidal and fine in the initial stage, but the particle size increases with the passage of time, and it is considered difficult to control them. The phosphate pigment produced in this way has an average particle size of 10 μm to several tens.
It is as large as .mu.m and, as disclosed in Japanese Patent Publication No. 49-2005, it is necessary to make it fine with a special crusher in order to mix it with the coating material. It should be noted that Japanese Patent Publication No. 46-12289 has already manufactured iron phosphate pigments having a uniform fine particle size. However, these zinc phosphate pigments and iron phosphate pigments have the drawback of being expensive. Also,
In JP-A-52-69898, a phosphate treatment liquid is allowed to act on an iron material to form a precipitate containing zinc phosphate and iron phosphate as main components, which is collected and dried to obtain a phosphate pigment. Although produced, the resulting pigment has poor alkali resistance, its color is limited, and its use is limited.
Also, as a green pigment, Japanese Patent Publication No. 30-4339 discloses a method for producing alumina-chromium, etc. However, it is necessary to avoid the use of chromium as much as possible because of environmental problems. As described above, at present, no inorganic pigments have been obtained which can control the color from iron phosphate and phosphate sludge, have good dispersibility, low cost and no environmental problems.

Regarding the disposal of phosphate sludge generated during the phosphating treatment of metallic materials, the recent strengthening of laws and regulations concerning industrial waste treatment, for example, in the end of 1995 in the Contracting States of the London Dumping Treaty, There is a ban on dumping into the ocean, which makes future waste treatment impossible, and we have to deal with it.

[0004]

[Problems to be Solved by the Invention]
It is an object of the present invention to provide a new method for producing an inorganic pigment from iron phosphate and / or phosphate sludge, and to recycle phosphate sludge.

[0005]

As a result of intensive studies on means for solving the above-mentioned problems, the inventors of the present invention have found that phosphorus generated in the phosphate chemical conversion treatment of iron phosphate and / or metal materials. It has been newly found that a novel inorganic pigment can be obtained by heat-pressurizing acidification sludge and iron in a closed pressure vessel, and completed the present invention.

That is, the present invention provides an iron suspension and an aqueous suspension having a pH of less than 7 containing 50% by weight or less of at least one kind of phosphate sludge generated in the phosphate chemical conversion treatment of iron phosphate and metallic materials. A phosphoric acid characterized in that it is filled in a closed pressure vessel and subjected to heat and pressure treatment, then the product containing a precipitate is filtered, the precipitate is collected, washed with water and dried to produce an inorganic pigment. Provided is a method for producing an inorganic pigment from iron and / or phosphate sludge.

The proportion of iron added to at least one of the phosphate conversion sludges generated in the phosphate conversion treatment of the iron phosphate and the metal material is such that the phosphate conversion of the iron phosphate and the metal material. It is preferable that 0.001 mol or more of 0-valent iron or 0.0005 mol or more of divalent iron ion is contained with respect to 1 mol of trivalent iron ions in the synthetic sludge.

The structure of the present invention will be described in detail below. The iron phosphate applicable to the present invention is not particularly limited as long as it is a commercially available reagent or a synthesized product. For example, the following product names can be given. 1) Ferrous phosphate octahydrate (8414 manufactured by Junsei Chemical Co., Ltd.)
0-1501) 2) Iron (II) phosphate octahydrate (FE150113 manufactured by Kojundo Chemical Research Institute Co., Ltd.) 3) O-iron phosphate (II) (P manufactured by Kojundo Chemical Research Institute Co., Ltd.)
120213) 4) Iron (II) phosphate octahydrate (Kanto Chemical Co., Ltd. 160
37-01) 5) Ferrous phosphate octahydrate (manufactured by DR PAUL LOHMAN GmbH) 6) Iron (III) phosphate dihydrate (FE150114, manufactured by Kojundo Chemical Laboratory Co., Ltd.) 7) o- Iron phosphate (III) (P120214 manufactured by Kojundo Chemical Laboratory Co., Ltd.) 8) Ferric phosphate tetrahydrate (manufactured by Junsei Chemical Co., Ltd. 8414)
5-1501, 1553) 9) Iron (III) phosphate tetrahydrate (manufactured by Kanto Chemical Co., Inc.) 10) Iron (III) phosphate n-hydrate (manufactured by Kanto Chemical Co., Ltd. 1
6028-01) 11) Iron (III) phosphate n-hydrate (Wako Pure Chemical Industries, Ltd.)
090-02702) 12) Iron (III) phosphate baked granules (Kanto Chemical Co., Inc.)
13) Ferric pyrophosphate (crystal) (Kanto Chemical Co., Ltd. 5
8214-43) 14) Ferric pyrophosphate solution (containing 2.5 to 3.5%)
(Kanto Chemical Co., Inc. 58214-43) 15) Iron (III) diphosphate solubility (Wako Pure Chemical Industries, Ltd. 090-02405) 16) Iron (III) phosphate calci
edgranular GR (Merck 393
5) 17) Ferric Pyrophosphate S
oluble Crystals (SIGMA CHEM
(Made by ICAL)

Further, the phosphate chemical conversion treatment liquid in the phosphate chemical conversion treatment varies depending on the type and purpose of the metal to be treated (eg, corrosion resistance, coating adhesion, base treatment for lubrication for plastic working, etc.). There are various types, but typical examples include zinc phosphate-based coating solution, manganese phosphate-based coating solution, iron phosphate-based coating solution and zinc calcium phosphate-based coating solution. .

Further, examples of the metal material to be subjected to the phosphate chemical conversion treatment include iron, zinc, aluminum and alloys thereof. Phosphate sludge, which is a by-product generated during the phosphate chemical conversion treatment of those metallic materials, is also applicable to the present invention. Table 1 shows a typical composition (dry state) of this phosphate sludge.

[0011]

[Table 1]

As shown in Table 1, in the composition of the dried phosphate sludge, the phosphate ion was contained most, followed by the iron ion. And most of them form phosphate compounds in the form of ferric phosphate.

In the production of the inorganic pigment according to the present invention, water is added to iron phosphate and / or phosphate sludge as required. The water to be added may be tap water, industrial water, deionized water or distilled water, but deionized water or distilled water is more preferable. The phosphate sludge can be treated without adding water if the water content is 50% by weight or more.

In the present invention, an aqueous suspension having a pH of less than 7 containing 50% by weight or less of at least one kind of phosphate sludge generated in the phosphate conversion treatment of iron phosphate and metallic materials is used. Therefore, an aqueous suspension containing both iron phosphate and phosphate sludge generated in the phosphate chemical conversion treatment of a metallic material can be used, and the mixing ratio thereof is not particularly limited. When the content of iron phosphate and / or phosphate sludge exceeds 50% by weight, the production rate of the inorganic pigment is extremely reduced, which is not preferable. Also, the pH
When it is 7 or more, the hydrothermal reaction does not occur and the inorganic pigment cannot be produced. However, since the pH of an aqueous suspension containing iron phosphate and / or phosphate sludge is usually 4 or less, it can be used as it is.

The iron content in the present invention is a general term for metallic iron or divalent iron ions. The metallic iron is preferably iron containing as few impurities as possible, but may be an iron pipe, iron powder, iron rod, iron sand, iron wire, steel plate, steel wool, iron scrap, or the like. Again 2
Valuable iron ions may be added.

The addition of iron is related to the adjustment of the color of the inorganic pigment. For example, addition of 0.001 mol of 0-valent iron or 0.0005 mol of divalent iron ion to 1 mol of trivalent iron ion in iron phosphate or phosphate sludge gives a light green color and 0-valent Add 0.05 mol of iron or 0.001 mol of divalent iron ion to green color, 0.1 mol of 0-valent iron or 0.05 mol of divalent iron ion to black-green color, and further add more iron. Because it can be adjusted to a blackish black green,
The amount of iron added is changed according to the required color. When the proportion of iron is less than 0.001 mol as 0-valent iron with respect to 1 mol of trivalent iron ion in iron phosphate and phosphate sludge,
Alternatively, if the amount of divalent iron ion is less than 0.0005 mol, the desired color cannot be adjusted.

A liquid prepared by adding iron necessary for producing a predetermined color to the above aqueous suspension containing iron phosphate and / or phosphate sludge is placed in a closed pressure vessel, sealed, and heated and pressurized. To process. It is preferable to use a closed pressure vessel having a heat resistant temperature of 300 ° C. or higher and a pressure resistance of 30 kg / cm ² G or higher. The heating and pressurizing conditions are not particularly limited, but the heating temperature is preferably 150 ° C or higher, more preferably 170 ° C or higher. The applied pressure is preferably 4 kg / cm ² G or more, more preferably 7 kg / cm ² G or more. After adjusting the iron phosphate or phosphate sludge content, pH, amount of iron added, heating temperature and pressure as described above, it is held for 2 hours or more. If it is less than 2 hours, the hydrothermal reaction is difficult to proceed.

After holding it for 2 hours or more, it is cooled to, for example, 100 ° C. or lower, and a cooling operation is performed to release the pressure to atmospheric pressure. Then, the closed pressure vessel is opened and the product is taken out. The product is filtered to collect a precipitate, which is washed with water and dried to obtain an inorganic pigment having an average particle size of 3 to 5 μm.

As a result of the X-ray diffraction analysis of the thus-collected inorganic pigment, it was found that the basic iron phosphate was Fe.
It was found to be ₃ (PO ₄ ) ₂ (OH) ₂ . As a comparison with this inorganic pigment, the X-ray diffraction result of iron (II) phosphate octahydrate is shown in FIG.

According to the method of the present invention, the inorganic pigment produced from iron phosphate and / or phosphate sludge does not dissolve in acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and therefore has very excellent acid resistance. ing. Alkali resistance with an aqueous sodium hydroxide solution is stable up to pH 12.5. Table 2 shows, as a comparison, the characteristics of typical inorganic pigments produced by the method of the present invention and the characteristics of iron oxide, which is a red pigment.

[0021]

[Table 2]

As shown in Table 2, the inorganic pigment obtained by the production method of the present invention can utilize the phosphate sludge generated during the phosphate chemical conversion treatment of the metal material as a raw material, and thus can be used as an industrial waste. It is very useful as a countermeasure against the pollution problem of and the pigment can be supplied at a low price. The iron added at the time of production can be used as a substitute for iron scraps, etc., so that iron-based waste can be reused. Since the obtained inorganic pigment has very good filterability, impurities can be easily removed by filtration and washing with water. It has a fine particle size of 3 μm to 5 μm and, as judged from the oil absorption amount in Table 2, has good dispersibility, and thus can be used as a pigment for various paints. A green inorganic pigment can be obtained from iron phosphate or phosphate sludge, and since it is an iron phosphate-based component, it has excellent rust prevention.

[0023]

EXAMPLES Examples of the present invention are shown below together with comparative examples, but the present invention is not limited to these examples.

Example 1 Commercially available reagent iron (II) phosphate octahydrate (Fe ₃ (PO ₄ ) ₂
8H ₂ O) 40 g, iron powder 0.67 g (0 valent iron 0.05 mole to 1 valent iron ion 1 mole), deionized water 3
59.33 g was put into a closed pressure vessel (capacity 500 ml, heat resistant temperature 300 ° C., pressure resistance 300 kg / cm ² G).
The content of iron (II) phosphate octahydrate is 10% by weight, p
H was 4.85. 200 r for contents of closed pressure vessel
While stirring at pm, temperature 170 ° C, pressure 7.2 kg /
It was heated and pressed to cm ² G and kept in that state for 8 hours. After cooling, the closed pressure vessel was opened and the product was taken out. The product was filtered, washed with water and dried to collect 30.65 g of a black-green inorganic pigment. The X-ray diffraction result of this inorganic pigment is shown in FIG.

From FIG. 2, it was found that the inorganic pigment was basic iron phosphate and the main component was Fe ₃ (PO ₄ ) ₂ (OH) ₂ .

Example 2 Ferric phosphate n-hydrate (FePO ₄ .nH) was used as a commercially available reagent.
₂ O) 40 g, iron scraps (cutting powder) 2.87 g, and deionized water 360 ml were placed in a closed pressure vessel (capacity 500 ml, heat resistant temperature 300 ° C., pressure resistance 300 kg / cm ² G). The content of this ferric phosphate n-hydrate is 9.93% by weight, p
H was 4.56. 200 r for contents of closed pressure vessel
While stirring at pm, temperature 170 ° C, pressure 7.2 kg /
It was heated and pressed to cm ² G and kept in that state for 8 hours. After cooling, the closed pressure vessel was opened and the product was taken out. The product was filtered, washed with water and dried to collect 24.37 g of a blue-green inorganic pigment. The X-ray diffraction result of this inorganic pigment is shown in FIG.

From FIG. 3, it was found that the inorganic pigment was basic iron phosphate and the main component was Fe ₃ (PO ₄ ) ₂ (OH) ₂ .

Example 3 Next, a chemical conversion treatment sludge (water content 55.5%) 18 taken from a phosphate conversion treatment line of an actual automobile body was used.
0 kg, industrial water 239.32 kg, steel wool 0.68 kg (0.05 mol of 0-valent iron to 1 mol of 3-valent iron ion) in a closed pressure vessel (capacity 0.5 m ³ , heat-resistant temperature 300 ° C., pressure resistance) 30 kg / cm ² G).
The chemical conversion treatment sludge content was 20% by weight, and the pH was 3.
It was 05. While stirring the contents of the closed pressure vessel at 250 rpm, a temperature of 190 ° C. and a pressure of 12.8 kg / cm ²
It was heated and pressurized to G and kept in that state for 6 hours. After cooling, the closed pressure vessel was opened and the product was taken out. The product was filtered, washed with water, and dried to collect 53.6 kg of a green inorganic pigment. The X-ray diffraction result of this inorganic pigment is shown in FIG.

From FIG. 4, it was found that the inorganic pigment was basic iron phosphate and the main component was Fe ₃ (PO ₄ ) ₂ (OH) ₂ .

Example 4 In addition, in order to change the color of the inorganic pigment, 180 kg of the chemical conversion treated sludge (water content 55.5%) used in Example 3, 218.6 kg of industrial water, 1.4 kg of steel wool (trivalent) Zero-valent iron (0.1 mol) per 1 mol of iron ion is sealed in a pressure vessel (capacity 0.5 m ³ , heat-resistant temperature 300 ° C., pressure resistance 3
0 kg / cm ² G). The content of the chemical conversion treatment sludge was 20% by weight, and the pH was 3.1. Close the contents of the closed pressure vessel at 250 rpm while stirring at 250 rpm.
℃, heat and pressure treatment to a pressure of 12.8 kg / cm ² G,
The state was maintained for 6 hours. After cooling, the closed pressure vessel was opened and the product was taken out. The product was filtered, washed with water and dried to collect 55.8 kg of a black-green inorganic pigment. The X-ray diffraction result of this inorganic pigment is shown in FIG.

From FIG. 5, it was found that the inorganic pigment was basic iron phosphate and the main component was Fe ₃ (PO ₄ ) ₂ (OH) ₂ .

Example 5 Next, a pigment was produced from the conversion conversion sludge generated from the zinc calcium phosphate treatment used in cold working of steel. This chemical conversion treatment sludge is in a dry state with PO ₄ ; 5
5.4 wt%, Fe; 18.8 wt%, Zn; 11.2
% By weight, Ni: 0.01% by weight, Mn: 0.2% by weight,
The composition was Na: 0.8% by weight, Ca: 0.7% by weight. And chemical conversion sludge (water content 30%) 11
4 kg, industrial water 284.5 kg, steel wool 1.
5 kg (0.1 mol of 0-valent iron ion to 1 mol of 3-valent iron ion) was put into a closed pressure vessel (capacity 0.5 m ³ , heat-resistant temperature 300 ° C., pressure resistance 30 kg / cm ² G). The chemical conversion treatment sludge content was 19.95% by weight and the pH was 3.02. 250 rpm for the contents of the closed pressure vessel
While stirring at 190 ° C, pressure 12.8 kg / c
It was heated and pressurized to m ² G and kept in that state for 6 hours. After cooling, the closed pressure vessel was opened and the product was taken out. The product was filtered, washed with water and dried to collect 52.6 kg of a black-green inorganic pigment. The X-ray diffraction result of this inorganic pigment is shown in FIG.

The characteristics and composition of the inorganic pigments collected in Examples 1, 2, 3, 4 and 5 are shown in Table 3. The dispersibility in Table 3 is obtained by blending a pigment with a paint and measuring the disperse particle size with a grind gauge particle size meter.
20 μm was considered good.

[0034]

[Table 3]

Further, a coating material was prepared as a trial with the inorganic pigment of Example 3 produced by the method of the present invention at the compounding ratio shown in Table 4. And
One-coat spray coating was applied on the SPCC-SD test panel and evaluated by the following coating film performance test method. The evaluation results are shown in Table 5. Here, the coating film performance test method will be described. Pencil hardness The pencil hardness is the limit point at which the coating film is not scratched. Cuts were made in 1 cm square at 1 mm intervals with a cutter knife to make cuts in the paint film, and the paint film was rapidly peeled off with a piece of cellophane tape, and the number of remaining goug marks was counted. Flexibility test A 20φ mandrel was bent 180 degrees around a shaft, and a film without peeling of the coating film was passed.

Water resistance test After immersing the coating film in water having a water temperature of 40 ° C. for 120 hours, the same goggles test was conducted to count the number of goggles that remained. Moisture resistance test A coated plate was left for 120 hours in an atmosphere of a temperature of 50 ° C. and a humidity of 98%, and a goose eye test was conducted in the same manner as in the above to count the number of remaining goug eyes. Abrasion resistance test A load of 1,000 g was applied on the coated plate, and the amount of peeling when sliding 1000 times was measured. Salt spray test Peeling width (mm) of black cut part after SST120Hr
Was measured.

[0037]

[Table 4]

[0038]

[Table 5]

The following can be said from the coating film performance test results of Examples 1 to 5 and Table 5. (1) The inorganic pigments of the present invention of Examples 1 to 6 have a hue of black green, blue green or green, have an average particle diameter of 3 to 5 μm and are excellent in dispersibility. (2) The inorganic pigment obtained in Example 3 has a green color, but since this color is changed, the amount of steel wool added is increased from that in Example 3 to produce the inorganic pigment. A different black-green inorganic pigment was obtained. As described above, by partially changing the production conditions of the present invention, the color of the obtained inorganic pigment can be adjusted from green to black green. (3) From the results in Table 5, for the paint using the inorganic pigment of the present invention of Example 3, pencil hardness, scoring test, flexibility test, water resistance test, moisture resistance test, abrasion resistance test and salt spray test. Also, the performance is excellent.

[0040]

INDUSTRIAL APPLICABILITY The inorganic pigment produced by the production method of the present invention is a novel inorganic pigment having a green, blue-green or black-green hue and having an average particle size of 3 to 5 μm and good dispersibility. Further, the color can be adjusted from green to blackish green by the manufacturing method of the present invention. Furthermore, by using the phosphate sludge generated in the phosphate chemical conversion treatment of a metal material as a raw material, the production method of the present invention enables effective use of the phosphate sludge as an inorganic pigment, and it can be used as industrial waste. Eliminates the need for disposal.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction diagram of an inorganic pigment and iron (II) phosphate octahydrate produced by the method of the present invention.

FIG. 2 is an X-ray diffractogram of an inorganic pigment produced by the method of the present invention from iron (II) phosphate octahydrate.

FIG. 3 is an X-ray diffraction diagram of an inorganic pigment produced by the method of the present invention from ferric phosphate hydrate (FePO ₄ .nH ₂ O).

FIG. 4 is an X-ray diffractogram of an inorganic pigment produced by the method of the present invention from automobile body phosphate conversion sludge.

FIG. 5 is an X-ray diffraction pattern of the inorganic pigment produced by the method of the present invention when the color is adjusted.

FIG. 6 is an X-ray diffraction pattern of an inorganic pigment produced by the method of the present invention from sludge containing calcium phosphate phosphate conversion treatment.

Claims (2)

[Claims] 1. A closed pressure vessel containing an iron suspension and an aqueous suspension having a pH of less than 7 containing 50 wt% or less of at least one kind of phosphate sludge generated in the phosphate conversion treatment of iron phosphate and a metal material. Iron phosphate and // characterized by producing an inorganic pigment by filling the inside and heating and pressurizing, and then filtering the product containing the precipitate, collecting the precipitate, washing with water, and drying. Alternatively, a method for producing an inorganic pigment from phosphate sludge. 2. An iron component added to an aqueous suspension having a pH of less than 7 containing 50% by weight or less of at least one of the phosphate chemical conversion sludge generated in the phosphate chemical conversion treatment of the iron phosphate and the metal material. Is 0.001 mol or more as 0-valent iron or 0.0005 mol or more as divalent iron ion with respect to 1 mol of trivalent iron ion in iron phosphate and / or phosphate sludge. The manufacturing method according to claim 1.