阅读说明：本技术 一种磁性球形颗粒的制备方法 (Preparation method of magnetic spherical particles ) 是由 杨俊佼 马梓栩 项顼 于 2021-09-09 设计创作，主要内容包括：本发明公开了一种磁性球形颗粒的制备方法。该方法的具体操作为：向铁盐和/或钴盐溶液中滴加氨水,通过沉淀反应得到溶胶,然后经过喷雾干燥成球形颗粒,最后高温煅烧成微米级磁性球形颗粒。与现有技术相比,本发明具有以下有益效果：1、无需添加任何粘合剂即可得到较好的球形度颗粒；2、可通过改变前驱体溶胶的固体含量和添加乙醇以及喷雾干燥的各种参数来控制喷雾干燥后粒径的大小；3、本发明制备出来的磁性颗粒粒径大小分布窄、磁性强,能够满足磁性油墨中磁性颗粒的要求；4、本发明无毒、无污染,操作简单,能量消耗低,成本低,可大规模批量生产；5、在前驱体溶胶中加入其他稀土元素,可以很便捷地改变磁性材料的磁性。(The invention discloses a preparation method of magnetic spherical particles. The method comprises the following specific operations: dropwise adding ammonia water into a ferric salt and/or cobalt salt solution, obtaining sol through precipitation reaction, then spray-drying to obtain spherical particles, and finally calcining at high temperature to obtain micron-sized magnetic spherical particles. Compared with the prior art, the invention has the following beneficial effects: 1. better sphericity particles can be obtained without adding any adhesive; 2. the size of the particle diameter after spray drying can be controlled by changing the solid content of the precursor sol and adding ethanol and various parameters of spray drying; 3. the magnetic particles prepared by the method have narrow particle size distribution and strong magnetism, and can meet the requirements of the magnetic particles in the magnetic ink; 4. the invention has no toxicity, no pollution, simple operation, low energy consumption and low cost, and can be produced in large scale; 5. other rare earth elements are added into the precursor sol, so that the magnetism of the magnetic material can be changed conveniently.)

1. A preparation method of magnetic spherical particles is characterized by comprising the following steps: dropwise adding ammonia water into a ferric salt and/or cobalt salt solution, obtaining sol through precipitation reaction, then spray-drying to obtain spherical particles, and finally calcining at high temperature to obtain micron-sized magnetic spherical particles.

2. The preparation method of claim 1, wherein the iron salt is one or more of ferric chloride, ferric nitrate and ferric sulfate.

3. The method according to claim 1, wherein the cobalt salt is cobalt chloride and/or cobalt nitrate.

4. The method according to claim 1, wherein the concentration of the iron salt and/or cobalt salt solution is 0.05-0.5 g/mL.

5. The production method according to claim 1, wherein the aqueous ammonia is added dropwise to a solution pH of 7.

6. The method as claimed in claim 1, wherein the inlet temperature of the spray drying is 150-180 ℃ and the outlet temperature is 90-100 ℃.

7. The method as claimed in claim 1, wherein the high-temperature calcination is a temperature programming, which is performed by raising the temperature to 250-280 ℃ at a rate of 2-10 ℃/min, maintaining the temperature for 2-5h, then raising the temperature to 600-1000 ℃ at a rate of 2-10 ℃/min, and maintaining the temperature for 0.5-2 h.

8. The preparation method according to claim 1, wherein during the spray drying, the sol and ethanol are simultaneously fed, and millimeter-sized magnetic spherical particles are finally obtained.

9. The method according to claim 8, wherein the volume ratio of the sol to the ethanol is 3-5: 1.

10. Use of magnetic spherical particles prepared according to any of claims 1 to 9 as magnetic cores for the preparation of magnetic inks or pigments.

Technical Field

The invention belongs to the technical field of magnetic materials, and particularly relates to a preparation method of micron-sized and millimeter-sized magnetic spherical particles, which can be applied to the fields of magnetic ink or magnetic optically variable ink and the like.

Background

The use of magnetics has expanded rapidly over the last decades. Magnetic materials have very wide application in our lives, such as application to souvenirs, refrigerators, magnets, information storage technologies, life-saving medical equipment and the like. The magnetic ink is mainly characterized in that some magnetic materials are added into the ink, for example, ferric oxide, ferroferric oxide and the like are added into the ink, so that the printed ink mark has magnetism, and information can be recorded and read out, therefore, the magnetic ink can be used in an anti-counterfeiting technology, substances such as cobalt and the like are added into the ferric oxide or the ferroferric oxide, and a magnetic detector can be used for detecting magnetic signals and decoding the magnetic signals. Magnetic ink has been used in the second thirty years of the past century, and has been developed to the present and applied to various fields such as security printing of bills, securities, credit cards and the like. The magnetic ink is almost the same as the common ink and consists of pigment, connecting material, stuffing and supplementary material, but the pigment of the common ink is pigment, while the pigment of the magnetic ink is ferromagnetic material, wherein the best magnetic pigment is Fe₃O₄And Fe₂O₃。

The ferric oxide is an inorganic substance and has the chemical formula of Fe₂O₃The surface of the paint is red or deep red, the covering power and the tinting strength are strong, and the paint has no oil permeability and water permeability, and is suitable for the paint and ink industry. Ferroferric oxide is an inorganic substance with the chemical formula of Fe₃O₄. The black iron oxide is also called magnetic iron oxide, is commonly used as pigment and polishing agent, and can also be used for manufacturing recording tapes and telecommunication equipment. The ferric oxide and the iron oxide black are main magnetic components of the magnetic ink, the ferric oxide and the iron oxide black have the advantages of low price, good effect and the like, but the surface color is dark, so the application of the ferric oxide and the iron oxide black is limited, if the surface of the ferric oxide and the iron oxide black is covered by other substances, the color of the surface of the ferric oxide and the iron oxide black is covered, and thus the ferric oxide and the iron oxide black do not displayThe magnetic material with the color and the light color surface has wider application prospect. We find in experiments that the particle size of common magnetic particles is different and irregular in shape, the surface of the common magnetic particles is not easily coated by other light-colored substances, the surface of micron-sized magnetic spherical particles can be coated more completely, most of magnetic particles sold in the current market are uneven in particle size or are irregular in shape, most of laboratory preparation methods are uneven in particle size and small in yield, and therefore the micron-sized magnetic spherical particles which are easy to cover the surface color can be prepared on a large scale.

However, in recent decades, although various effective methods for preparing nano-scale and micron-scale iron oxide black have been developed at home and abroad, such as mechanical ball milling, coprecipitation, sol-gel, microemulsion, thermal decomposition, solvothermal method, etc., most of the methods have a series of disadvantages, such as high manufacturing cost, low yield, long time, uneven particle size distribution, etc., while some specific production process technologies at home and abroad are confidential to break the technical monopoly at home and further exploration is needed to master a simple method for large-scale preparation.

Disclosure of Invention

Aiming at the problems of high manufacturing cost, long time, small yield, uneven particle size distribution and the like in the prior art for preparing magnetic particles, the invention provides a preparation method of magnetic spherical particles, which can be applied to magnetic core raw materials required in the preparation of magnetic ink and magnetic optically variable ink.

The preparation method of the magnetic spherical particles comprises the following steps: dropwise adding ammonia water into a ferric salt and/or cobalt salt solution, obtaining sol through precipitation reaction, then spray-drying to obtain spherical particles, and finally calcining at high temperature to obtain micron-sized magnetic spherical particles.

The ferric salt is one or more of ferric chloride, ferric nitrate and ferric sulfate.

The cobalt salt is cobalt chloride and/or cobalt nitrate.

The concentration of the ferric salt and/or cobalt salt solution is 0.05-0.5 g/mL.

The ammonia is added dropwise until the pH value of the solution is 7.

The air inlet temperature of the spray drying is 150-180 ℃, and the air outlet temperature is 90-100 ℃.

The high-temperature calcination is temperature programming, the temperature is raised to 280 ℃ at the temperature raising rate of 2-10 ℃/min, the temperature is kept for 2-5h, then the temperature is raised to 1000 ℃ at the temperature raising rate of 2-10 ℃/min, and the temperature is kept for 0.5-2 h.

During spray drying in the preparation method, the sol and the ethanol are simultaneously fed, and the millimeter-scale magnetic spherical particles are finally obtained. The volume ratio of the sol to the ethanol is 3-5: 1.

The magnetic spherical particles prepared by the method are used as magnetic cores to prepare magnetic ink or magnetic pigments.

Compared with the prior art, the invention has the following beneficial effects: 1. better sphericity particles can be obtained without adding any adhesive; 2. the size of the particle diameter after spray drying can be controlled by changing the solid content of the precursor sol and adding ethanol and various parameters of spray drying; 3. the magnetic particles prepared by the method have narrow particle size distribution and strong magnetism, and can meet the requirements of the magnetic particles in the magnetic ink; 4. the invention has no toxicity, no pollution, simple operation, low energy consumption and low cost, and can be produced in large scale; 5. other rare earth elements are added into the precursor sol, so that the magnetism of the magnetic material can be changed conveniently.

Drawings

FIG. 1 is a Scanning Electron Micrograph (SEM) of iron hydroxide particles prepared by spray drying according to example 1.

Fig. 2 is a scanning image (SEM) of the magnetic spherical particles after calcination prepared in example 1.

FIG. 3 is a graph showing a distribution of the particle diameters of the magnetic spherical particles after calcination, obtained in example 1.

Fig. 4 is a photograph of the magnetic spherical particles after calcination obtained in example 2.

Detailed Description

Example 1

A. 15g of FeCl₃Adding 70mLH₂Dissolving in O under stirring, wherein the solution is light yellow; then placing in a constant temperature water bath at 25 ℃, starting stirring, and passing through a constant pressureSlowly dripping 50mL of 10% ammonia water into the three-neck flask by using a dropping funnel, continuously stirring for 140min after about 40min, and stopping stirring after the pH value of the solution is stabilized at 7 to obtain ferric hydroxide sol;

B. setting technological parameters of a spray dryer, air inlet temperature: 170 ℃, air outlet temperature: 95-100 ℃, feeding speed of a peristaltic pump: 12RPM, fan frequency: 35HZ, feeding 40mL of iron hydroxide sol by spray drying each time, and collecting the spray-dried iron hydroxide particles in a material receiving tank;

C. and (2) placing the ferric hydroxide particles in a crucible, continuously drying for 7h at 200 ℃ in an oven, finally placing in a muffle furnace, setting a program for heating, heating to 265 ℃ at a heating rate of 3 ℃/min, keeping for 4h, continuously heating to 700 ℃ at a heating rate of 3 ℃/min, and keeping for 1h to obtain the micron-sized magnetic spherical particles.

Example 2

A. 15g of FeCl₃Adding 68mLH₂Dissolving in O under stirring, wherein the solution is light yellow; then placing the solution in a thermostatic water bath at 25 ℃, starting stirring, slowly dripping 50mL of ammonia water with the mass concentration of 10% into a three-neck flask through a constant-pressure dropping funnel, continuing stirring for 140min after dripping is finished for about 40min, and stopping stirring after the pH value of the solution is stabilized at 7 to obtain ferric hydroxide sol;

B. setting technological parameters of a spray dryer, air inlet temperature: 170 ℃, air outlet temperature: 95-100 ℃, feeding speed of a peristaltic pump: 12RPM, fan frequency: 35HZ, feeding 40mL of ferric hydroxide sol and 10mL of ethanol in each spray drying process, and collecting the spray-dried ferric hydroxide particles in a material collecting tank;

C. and (2) placing the iron hydroxide particles in a crucible, then continuously drying for 7h at 200 ℃ in an oven, finally placing in a muffle furnace, setting a program for heating, heating to 265 ℃ at a heating rate of 10 ℃/min, keeping for 4h, then continuously heating to 900 ℃ at a heating rate of 3 ℃/min, and keeping for 1h to obtain the millimeter-sized magnetic spherical particles.