KR100445601B1 - Functional Pigment Using Low Purity Of Iron Salt And Method Of Making The Same - Google Patents

Abstract

The present invention relates to a functional pigment using a low-purity iron salt and a method for producing a functional pigment. Synthesis of seed material for preparing iron oxide by adding alkali to a mixed solution prepared with ferrous salt (II) solution and ferric salt (III) solution step; The seed material was repeatedly adsorbed on the surface of the seed material by adsorbing iron hydroxide (II), which was prepared separately from the low-purity ferrous salt (II) solution and stored in a non-oxidizing atmosphere, and then oxidized with an oxygen-containing gas. Continuously growing; A washing step of washing away impurities contained in the magnetite after the seed material growth is completed; It characterized in that it comprises a drying and continuous atmosphere controlled heat treatment step in the continuous heat treatment apparatus.

According to the present invention, using a crude iron sulfate solution as a starting material, the step of synthesizing the seed material, the repetitive growth step of the seed material, the washing step of the grown magnetite particles, the heat treatment with an atmosphere gas at the same time drying in a continuous heat treatment apparatus It is economical than the magnetite manufactured by using the high purity raw material by the step process, and its excellent magnetic properties, oxidation temperature, and reducing ability makes it useful as a functional pigment and reducing catalyst for high quality toner, Accordingly, various pigments such as brown, red, and black may be prepared.

Description

Functional Pigment Using Low Purity Of Iron Salt And Method Of Making The Same}

The present invention relates to a functional pigment and a method for producing a functional pigment using a low purity iron salt.

According to the present invention, magnetic iron oxide having a mineral phase of magnetite (γ-Fe ₂ O ₃ ), and magnetic iron oxide for toner having a mineral phase of magnetite (α-Fe ₃ O ₄ ) using an inexpensive low-purity iron salt, as well as a magnetic iron oxide having a mineral phase of A pigment of brown color and a pigment of red color having a mineral phase of hematite (α-Fe ₂ O ₃ ) can also be easily produced.

In general, iron salts can be obtained as a by-product in the large steel industry and titanium dioxide manufacturing process in abundant and inexpensive manner, and are currently mainly used as iron oxide or red pigment for soft ferrite and hard ferrite. However, black magnetic pigments using this rich iron salt are not used because of lack of technology and economic feasibility. The lack of economics is due in particular to the need for a purification process for high purity, resulting in high manufacturing costs. Iron salts produced in Korea are mainly made up of iron sulfate and iron chloride.

The manufacturing method of iron salt products is largely divided into dry method, wet method and spray roasting method. The spray roasting method is a method of roasting by spraying an aqueous solution of ferric chloride alone or a mixed solution of ferric chloride into a roasting furnace that maintains a temperature range of 500 ° C to 1000 ° C in an atmosphere containing or without oxygen. This is a method that is simple and short manufacturing process, low production cost is widely used for mass production. The iron oxide having the mineral phase of hematite obtained here is commercially active in the field of Ferrite, but the iron oxide having the mineral phase of magnetite obtained in the non-oxygen atmosphere is not only easy to mix the mineral phase of hematite, but also deteriorates the magnetic properties. Due to the uneven particle size and magnetic properties, there are many problems to be used as a functional pigment for high quality toner. The method of manufacturing hematite by dry method is a method of synthesizing magnetite by one-step wet method and then heat-treating in two-step oxidizing atmosphere. It is economical to be used as low-purity hematite and before synthesis of one-step wet method Purification process must be performed. The high process cost in the refining process is a big burden on the manufacturing cost. In the wet method, an aqueous solution in which iron sulfate or iron chloride is dissolved in water is added to an aqueous solution in which Alkali is dissolved, followed by stirring, followed by heating while injecting an oxidizing gas. At this time, it is possible to produce various iron oxides or hydrous iron oxides having various colors and particle shapes depending on the synthesis conditions, but if the by-products are used without undergoing a purification process, color or magnetic properties are deteriorated due to the influence of impurities. In addition, in the case of magnetite, surface oxidation is likely to occur, and various surface coatings are used to suppress it and improve dispersion characteristics.

As the alkali, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium silicate, potassium silicate, lithium silicate, sodium carbonate, potassium carbonate, lithium carbonate, sodium polyphosphate, potassium polyphosphate, lithium polyphosphate and the like are used. As the surface coating, hydrophobing agents such as organometallic compounds, oils, powders, and resins, and inorganic elements such as Al, Ti, Mg, Si, Co, Zr, Mn, Zn, and Cu are used. These surface coating methods are difficult to uniformly coat very fine particle surface of 100 ~ 400nm, and the coatings are agglomerated with each other, causing uneven distribution of coatings. This acts as a factor of lowering the saturation magnetization value and the residual magnetization value, especially when used as a pigment using magnetic properties.

In the present invention is to solve the problems in the conventional manufacturing method of various iron oxides, such as by-product as a raw material without refining process is inexpensive, magnetic properties, catalyst properties, pigment properties, etc. as compared to a product manufactured from a raw material It is an object of the present invention to provide a method for producing this excellent functional black iron oxide and brown and red pigment.

1 is a schematic configuration diagram of a heat treatment apparatus for continuously performing drying and crystal phase control of a magnetite prepared through a wet synthesis step by adjusting an atmosphere gas;

<Description of the symbols for the main parts of the drawings>

1: raw material feeder 2: raw material feeder

3: heat treatment apparatus 4: air supply port

5: nitrogen gas supply port 6: hydrogen gas supply port

7, 8, 9: gas outlet

The present invention for achieving the above object relates to a method for producing an economical and high-quality functional pigment using low-purity iron salt that can be obtained inexpensively and abundantly in Korea, and a low-purity ferrous salt (II) solution and a second Synthesizing the magnetite seed material by mixing the iron salt (III) solution in a predetermined ratio: Repeating the growth of the magnetite by iron hydroxide (II) or ferrous salt (II) solution and alkaline aqueous solution: with water The washing step: characterized by consisting of a continuous heat treatment step for drying and mineral phase by adjusting the atmosphere gas in the heat treatment apparatus below 500 ℃. Atmospheric gas refers to air, oxygen gas, hydrogen gas, ammonia gas, carbon monoxide gas, nitrogen gas, and mixed gas thereof for controlling oxidation and reducing atmospheres.

Magnetic iron oxide having a mineral phase of magnetite (γ-Fe ₂ O ₃ ) for toner having a mineral phase of magnetite (α-Fe ₃ O ₄ ), and magnetite (γ-Fe ₂ O ₃ ) according to the purpose of the material to be obtained through such a step process, and Various kinds of iron oxides can be produced according to the use and purpose, such as a brown pigment and a red pigment having a mineral phase of hematite (α-Fe ₂ O ₃ ). In particular, the black magnetic iron oxide is excellent in magnetic properties and blackness by controlling the reduction degree (x) in the chemical formula represented by Fe ₃ O _4-x , which is not only suitable for toners but also as an economical reduction catalyst. Can be used. In addition, the heat treatment apparatus may have a structure as shown in FIG. 1, and the method of manufacturing the functional pigment according to the present invention using the heat treatment apparatus shown in this drawing will be described in more detail as follows. It should be noted that in the following description, only parts necessary for understanding the manufacturing method according to the present invention will be described, and descriptions of other parts will be omitted so as not to obscure the subject matter of the present invention.

Seed material synthesis step, the ferrous salt (Ⅱ) solution of ferric salt (Ⅲ) using a solution by adjusting the charge ratio to ^{Fe +2 / Fe +3 = 0.4 ~} 1.0 , and an alkali (OH ^-) / (Fe ⁺² + Fe ⁺³ ) = 1.6 ~ 5.0 At this time, the temperature of the solution is to maintain more than 50 ℃. In the next growth step of the seed material, the iron hydroxide (II) or ferrous salt (II) solution previously stored in a non-oxidizing atmosphere and an aqueous alkali solution are continuously grown by at least one or more repetitive methods. In the repetitive growth stage, air or oxygen and a mixture of these and inert gases are used. Repetitive is a method in which iron hydroxide (II) for seed material growth is gradually added continuously and deposited on the surface layer of seed material, oxidized by stopping the input for a certain time, and then restarting iron hydroxide (II) again. it means. In this process, 0.02% by weight or less of B, Nb, P,, Pt, W, Sr, V, Y, Mo, Pd, in order to improve magnetic properties, oxidation resistance, catalytic properties and densification of particles One or more elements selected from Ba are added. This method results in the formation of several layers of protective layers, which in particular have an effect on the oxidation resistance. In addition, there is an advantage in that uniform particles can be obtained in a desired size. In the washing step, Na, K, S, Cl, etc., which act as impurities, are washed off with water. Aqueous ammonia, caustic soda, hydrochloric acid and sulfuric acid are used depending on the pH of the grown particles for efficient flushing.

The heat treatment step can be largely divided into two sections. In the front section of the heat treatment device with a heating device, a drying process to remove moisture contained in the grown magnetite particles is carried out. In the rear section, the atmospheric gas below 500 ℃ is adjusted to change the mineral phase and the surface characteristics of the particles. It is characterized by consisting of a continuous heat treatment step for controlling. In particular, by using the latent heat in the drying process as it is a continuous weak reduction heat treatment, economical reduction heat treatment is possible.

Continuously supplying the washed and dehydrated magnetite composite product from the raw material feeder 1 to the raw material feeder 2 is carried out in the heat treatment apparatus 3 in the direction of the arrow to perform continuous drying and oxidation or reduction heat treatment.

In order to obtain a black magnetic pigment for the reduction catalyst or toner having a mineral phase of magnetite (α-Fe ₃ O ₄ ) according to the use and purpose of the material to be obtained in this process, the flow rate of the hydrogen gas supply port 6 is increased, Reduce the flow rate of the air supply port (4), open the damper of the gas outlet (7) to further suppress the oxidizing atmosphere as possible, control the reducing atmosphere to heat treatment, having a mineral phase of hematite (α-Fe ₂ O ₃ ) In order to obtain red pigment or ferrite iron oxide, on the contrary, the nitrogen gas supply port 5 and the hydrogen gas supply port 6 are closed, and the damper is adjusted so that the emissions from the gas outlets of (7) and (8) are increased. In order to obtain a pigment of magnetic iron oxide and brown system having a mineral phase of brown margeite (γ-Fe ₂ O ₃ ), the atmosphere and temperature are controlled to be in the middle of the two conditions. Skillful driving skills are required. After the heat treatment, various iron oxides may be pulverized depending on the application.

When manufacturing pigments through these steps, not only can the manufacturing cost be reduced by using rich and inexpensive raw materials, but also high quality properties can be obtained. Functional pigment for toner, reducing catalyst, paint, rubber, printing ink, construction It can be used in a wide range of fields such as materials, ceramic products and synthetic resins.

The various iron oxides prepared above are measured by the following method.

1. Mineral phase analysis:

The analysis was performed using an X-ray diffraction analyzer (XRD), and the analysis conditions were 40 KV, 15 mA, CuKα, and a scanning speed of 0.02 ° / min.

2. Magnetic characteristic measurement:

It was measured using a vibration-type magnetic measuring system (VSM), the measurement conditions were the maximum applied magnetic field of 5 KOe, the filling density of about 1.0 g / cc at room temperature.

3. Measurement of oxidation temperature and reduction degree (x)

Using a thermogravimetric analyzer (TGA) to increase the temperature to 500 ℃ 5 ℃ / min to obtain a graph of the weight change with temperature. The oxidation temperature was determined as the temperature at which the extension line connecting the point at 80% of the maximum weight change and the point at 20% meets the line at weight change = 0.

The present invention will be described in more detail based on Examples as follows, but the present invention is not limited to the Examples.

Example 1

A mixed aqueous solution of unpurified FeSO ₄ · 7H ₂ O and Fe ₂ (SO 4) ₃ · nH ₂ O was charged to Fe ^{+ 2} / Fe ⁺³ = 1.0, and then a NaOH aqueous solution was added to (OH ⁻ ) / (Fe ⁺² + Fe ⁺³ ) = 2.6 with air to synthesize the seed material for 30 minutes at 80 ℃. In the seed material growth stage, air was stopped and Fe (OH) ₂ , which was prepared in advance and stored in a nitrogen gas atmosphere, was continuously added. 10 minutes after the 20% by volume of the total Fe (OH) ₂ was added, the air was restarted and oxidized for 30 minutes. Thereafter, Fe (OH) _{2 was} added and air oxidation was performed four more times in the same manner. In an iterative process for seed material growth, B was added to 0.005% of the total Fe ₃ O ₄ . The magnetite with complete particle growth was washed with water and then filtered. The filtered magnetite was pulverized after heat treatment at 250 ° C. and a hydrogen gas flow rate of 100 L / min in a continuous heat treatment apparatus as shown in FIG. 1. The results are shown in the following [Table 1] and [Table 2].

Example 2

Except that the heat treatment temperature in the continuous heat treatment apparatus to 150 ℃ was carried out in the same manner as in Example 1, the results are shown in the following [Table 1] and [Table 2].

Example 3

The mixed aqueous solution was synthesized in the same manner as in Example 2 except that the mixed aqueous solution was prepared to have Fe ^{+ 2} / Fe ^{+ 3} = 0.5, and the results are shown in the following [Table 1] and [Table 2].

Example 4

Hydrogen gas in the continuous heat treatment apparatus was carried out in the same manner as in Example 1, except that the input amount of 20 L / min, the results are shown in the following [Table 1] and [Table 2].

Example 5

Except not performing hydrogen gas in the continuous heat treatment apparatus was carried out in the same manner as in Example 1, the results are shown in the following [Table 1] and [Table 2].

Comparative Example 1

The aqueous FeSO ₄ · 7H ₂ O solution was neutralized with NaOH to have a pH of 3 or more, to precipitate impurities, and then a high-purity purified filtrate was used to remove the precipitate. (OH ^-) in a first aqueous solution of NaOH added into the reactor to a ferrous sulfate aqueous solution so that the tablet ^{/ (Fe +2 + Fe +3)} = 2.6 In the air with the magnetite was synthesized during 80 ℃, 10 hours. After filtering the synthetic material and dried in an air atmosphere at 80 ℃ for 24 hours, the results are shown in the following [Table 1] and [Table 2].

Comparative Example 2

Except for omitting the growth step of the seed material was carried out in the same manner as in Example 1, the results are shown in the following [Table 1] and [Table 2].

According to the present invention, using a crude iron sulfate solution as a starting material, the step of synthesizing the seed material, the repetitive growth step of the seed material, the washing step of the grown magnetite particles, the heat treatment with an atmosphere gas at the same time drying in a continuous heat treatment apparatus It is economical than the magnetite manufactured by using the high purity raw material by the step process, and its excellent magnetic properties, oxidation temperature, and reducing ability makes it useful as a functional pigment and reducing catalyst for high quality toner, Accordingly, various pigments such as brown, red, and black may be prepared.

As described above, the present invention has been described in detail only with respect to the described embodiments, but it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and modifications belong to the appended claims. It is natural.

Claims (9)

A seed material synthesis step of preparing iron oxide by adding alkali to a mixed solution prepared with a ferrous salt (II) solution and a ferric salt (III) solution; The seed material was repeatedly adsorbed on the surface of the seed material by adsorbing iron hydroxide (II), which was prepared separately from the low-purity ferrous salt (II) solution and stored in a non-oxidizing atmosphere, and then oxidized with an oxygen-containing gas. Continuously growing; A washing step of washing away impurities contained in the magnetite after the seed material growth is completed; Method for producing a functional pigment using a low-purity iron salt comprising a drying and continuous atmosphere controlled heat treatment step in a continuous heat treatment apparatus. According to claim ^{1, Fe +2 / Fe +3 = 0.4} ~ 1.2 for the alkali solution to be manufactured by mixing the ^{(OH -) / (Fe +2} + Fe +3) to be put into a = 1.6 ~ 3.6, 50 Continuous seed material including the step of synthesizing the seed material prepared at ℃ ℃ and the method of oxidizing for at least 5 minutes by restarting the oxygen-containing gas after the addition of the iron hydroxide (II) and at least once at 70 to 100 ℃ Method for producing a functional pigment using a low-purity iron salt, comprising the step of growth and superimposed in the drying process at a continuous gas heat treatment at 120 to 500 ℃. The low purity iron salt of claim 1, wherein Mn and Ti in the ferrous salt (II) solution and the ferric salt (III) solution are each contained at least 0.2% by weight relative to the total Fe. Method for producing a functional pigment using a purity iron salt. The method of claim 1, wherein the functional pigment prepared contains at least one element selected from B, Nb, P, Sr, V, Y, Mo, Pd, and Ba in an amount of 0.001 to 0.02% by weight relative to the total Fe. Method for producing a functional pigment using a low purity iron salt, characterized in that. The functional pigment using low-purity iron salt of claim 1, wherein hydrogen atmosphere, nitrogen gas, ammonia gas, carbon dioxide gas, oxygen gas, air, and a mixture thereof are used during the atmosphere control heat treatment in the continuous heat treatment step. Manufacturing method. _Two surface layers having a degree of reduction (x) of -0.5 to 1.5 from the surface of the iron oxide represented by Fe ₃ O _4-x and an inner layer having a difference of at least 0.1 from the surface layer. The functional pigment using the low purity iron salt which has the above heterogeneous structure, Mn is 0.2 weight% or more with respect to total Fe, and 0.5 weight% or more of Ti is contained. A toner containing a functional pigment prepared according to claim 1. A reduction catalyst containing a functional pigment prepared according to claim 1. A paint containing a functional pigment prepared according to claim 1.