阅读说明：本技术 一种强磁场条件下高抗磁沉降性密封用磁性流体的制备方法 (Preparation method of magnetic fluid for high-magnetic-sedimentation-resistance sealing under strong magnetic field condition ) 是由 黄波 布和*** 李鹏 张晓臣 那宏壮 隋新 于 2019-11-13 设计创作，主要内容包括：一种强磁场条件下高抗磁沉降性密封用磁性流体的制备方法,它涉及磁性流体的制备方法。它是要解决现有的磁性流体的高磁场下抗磁沉降性低的技术问题。本方法：先制备粒径为5～15纳米的Fe<Sub>3</Sub>O<Sub>4</Sub>粉；再将其均匀地分散在环己烷中,加入抗氧剂和分散剂对它进行第一次表面修饰与包覆；接着采用双极性液相转移法将已进行表面修饰与包覆的纳米Fe<Sub>3</Sub>O<Sub>4</Sub>转移到庚烷中,再加入抗氧剂和分散剂对其进行二次表面修饰与包覆,然后将其与金属钝化剂及粘度调节剂加入到合成烃基础油中反应,得到磁性流体。该用磁性流体的饱和磁化强度为498～570GS,在室温1.0T磁场条件下的抗磁沉试验,720小时以上无分离现象。可用于真空密封、阻尼减震领域。(A preparation method of a magnetic fluid for sealing with high magnetic sedimentation resistance under the condition of a strong magnetic field relates to a preparation method of a magnetic fluid. The magnetic fluid aims to solve the technical problem that the existing magnetic fluid is low in anti-magnetic settling property under a high magnetic field. The method comprises the following steps: firstly, preparing Fe with the particle size of 5-15 nanometers 3 O 4 Pulverizing; then uniformly dispersing the mixture in cyclohexane, and adding an antioxidant and a dispersant to carry out primary surface modification and coating on the mixture; then adopting a bipolar liquid phase transfer method to carry out surface modification and coating on the nano Fe 3 O 4 Transferring into heptane, adding antioxidant and dispersant to perform secondary surface modification and coating, and adding metal deactivator and viscosity regulator into synthetic hydrocarbon base oil to react to obtain magnetic fluid. The magnetic fluid has the saturation magnetization of 498-570 GS, and has no separation for more than 720 hours in an anti-magnetic precipitation test under the room temperature and 1.0T magnetic field conditionA phenomenon. Can be used in the fields of vacuum sealing and damping shock absorption.)

1. A preparation method of a magnetic fluid for high-magnetic-sedimentation-resistance sealing under the condition of a strong magnetic field is characterized by comprising the following steps:

firstly, preparing Fe with the particle size of 5-15 nanometers₃O₄Magnetic powder:

secondly, weighing nano Fe₃O₄The lubricant comprises powder, a first antioxidant, a first dispersing agent, a second antioxidant, a second dispersing agent, a metal deactivator, a viscosity regulator and synthetic hydrocarbon base oil;

wherein the first antioxidant is barium petroleum sulfonate, dodecenylsuccinic acid, 4' -dioctyl diphenylamine, dodecenylsuccinic acid, zinc diisooctyl dithiophosphate or high-alkali sulfurized calcium alkyl phenolate;

the first dispersant is: polyisobutylene mono-succinimide, nonyl (octyl) phenol polyoxyethylene ether, diphenyl-p-isooctyl phosphate, sodium fatty alcohol polyoxyethylene ether sulfate, ashless polyisobutylene butylene diamide or alkenyl succinate;

the second antioxidant is octyl diphenylamine, β -mercaptopropionic acid, β -mercaptopropionic acid, trimethylhexadecylammonium bromide, alkylated diphenylamine or octylphenyl α naphthylamine;

the second dispersing agent is: polyvinyl n-butyl ether, boronized succinimide, sodium linear alkylbenzene sulfonate, dialkyl dithiocarbamate, nonylphenol polyoxyethylene ether or high molecular weight polyisobutylene polysuccinimide;

III, according to nanometer Fe₃O₄Quality of the powderThe percentage concentration of the nano Fe is 50 to 55 percent₃O₄Adding the powder into cyclohexane, heating to 65-80 ℃ under the high-speed stirring condition of 4000-4500 rpm, adding a first dispersing agent and a first antioxidant, stirring for 10-20 minutes under the condition of 65-80 ℃, carrying out magnetic precipitation for 10-15 minutes, filtering by using filter cloth of 200-400 meshes, filtering out large particles and insoluble substances, and obtaining the surface-activated and modified nano Fe₃O₄Suspending the solution;

fourthly, activating and modifying the surface of the nano Fe₃O₄Adding the suspension solution into a reaction kettle with a circulating condensation system, adding heptane under the high-speed stirring condition with the rotating speed of 5000-6500 rpm, heating to 70-85 ℃, continuously stirring for 2-4 hours, and evaporating to remove cyclohexane to obtain nano Fe₃O₄A heptane dispersion of (1);

fifth, nanometer Fe in the reaction kettle₃O₄Adding a second dispersing agent and a second antioxidant into the heptane dispersion liquid, heating to 100-120 ℃, simultaneously starting a circulating water condensation system for reflux reaction for 1-2 hours, and cooling to room temperature to obtain secondary surface modified nano Fe₃O₄Magnetic powder-heptane pre-dispersion;

sixthly, adding the synthetic hydrocarbon base oil into a container, heating to 80-100 ℃, adding a metal passivator and a viscosity regulator under the high-speed stirring condition of 5000-6500 rpm, continuously stirring for 30-50 minutes, and then carrying out secondary surface modification on the nano Fe₃O₄Adding the magnetic powder-heptane pre-dispersion liquid into synthetic hydrocarbon base oil, simultaneously heating to 150-165 ℃, reacting for 2-4 hours under the high-speed stirring condition of 5000-6500 rpm, cooling to 100 ℃, placing a container on a magnet, and standing to room temperature to obtain the magnetic fluid with high magnetic sedimentation resistance under the condition of a strong magnetic field.

2. The method for preparing the magnetic fluid for sealing with high magnetic sedimentation resistance under the condition of the strong magnetic field according to claim 1, wherein Fe with the particle size of 5-15 nm is adopted in the step one₃O₄The preparation method of the magnetic powder comprises the following steps:

(1) to the mass percentage concentration of 25-30%Introducing nitrogen into NaOH aqueous solution to drive oxygen, continuously introducing nitrogen to form protective atmosphere, and stirring FeCl₂With FeCl₃Dropwise adding the mixed aqueous solution into a NaOH aqueous solution, heating to 60-85 ℃ after dropwise adding, dropwise adding a surfactant, stirring and reacting for 20-40 minutes at 80-85 ℃ after dropwise adding the surfactant, and continuously introducing nitrogen for atmosphere protection in the reaction process to obtain a suspension; wherein FeCl₂With FeCl₃FeCl in the mixed aqueous solution of₂With FeCl₃Is 1: (1.5-2.5); FeCl₂With FeCl₃In the mixed aqueous solution of FeCl₂The mass percentage concentration of the active carbon is 50-60 percent; the surfactant is added in an amount of FeCl₂、FeCl₃5-15% of the total mass of the components;

(2) transferring the suspension into a hydrothermal synthesis kettle, placing the hydrothermal synthesis kettle in an oven with the temperature of 120-150 ℃ for heat preservation for 4-6 hours, washing the product with deionized water and ethanol in sequence after the reaction is finished, filtering and drying to obtain the nano Fe₃O₄Pulverizing; the nano Fe₃O₄The particle size of the particles is 5-15 nm.

3. The method for preparing the magnetic fluid for sealing with high magnetic sedimentation resistance under the condition of the strong magnetic field according to claim 2, wherein the surfactant in the step (1) is one or a combination of more of oleic acid, sodium (Z) -9-octadecenylate, ethoxylated alkyl fatty alcohol polyoxyethylene ether, sodium dodecyl benzene sulfonate, linear tetrapropenyl sodium benzene sulfonate and barium methylenedinaphthalene sulfonate.

4. The method for preparing the magnetic fluid for sealing with high magnetic settling resistance under the condition of the strong magnetic field according to claim 1, 2 or 3, characterized in that the metal passivator in the second step is N-cyclohexyl-N-phenyl-p-phenylenediamine, trimethyl hexadecyl ammonium bromide, N-12 alkyl thiazole mercaptan, 2, 5-di (tert-dodecyl-dithio) -1,3, 4-thiadiazole, methyl benzotriazole derivative or 2,6-, di-tert-butyl- α dimethylamino-p-cresol.

5. The method for producing a magnetic fluid for sealing with high magnetic settling resistance under high magnetic field conditions according to claim 1, 2 or 3, wherein the viscosity modifier in the second step is: polymethacrylate, polyisobutylene, hydrogenated styrene diene copolymer, trimethylolpropane oleate, polymethacrylate or polyisobutylene.

6. The method for preparing a magnetic fluid for sealing with high magnetic settling resistance under the condition of a strong magnetic field according to claim 1, 2 or 3, wherein the mass of the surfactant in the second step is nano Fe₃O₄1-3% of the powder.

7. The method for preparing the magnetic fluid for high magnetic settling resistance sealing under the condition of the strong magnetic field according to claim 1, 2 or 3, wherein the mass of the first antioxidant in the second step is nano Fe₃O₄1-3% of the powder.

8. The method for producing a magnetic fluid for sealing with high magnetic settling resistance under high magnetic field conditions as claimed in claim 1, 2 or 3, wherein the first dispersant in the second step is nano-Fe by mass₃O₄1 to 2.5 percent of the powder by mass.

9. The method for preparing a magnetic fluid for high magnetic settling resistance sealing under high magnetic field conditions as claimed in claim 1, 2 or 3, wherein the second antioxidant in step two is nano Fe in mass₃O₄1-3% of the powder.

10. The method for producing a magnetic fluid for sealing with high magnetic settling resistance under high magnetic field conditions as claimed in claim 1, 2 or 3, wherein the first dispersant in the second step is nano-Fe by mass₃O₄1 to 2.5 percent of the powder by mass.

Technical Field

The invention relates to a preparation method of magnetic fluid.

Technical Field

The magnetic fluid is a magnetic and flowable non-Newtonian fluid functional material, and nanometer ferrite particles are uniformly dispersed in organic or inorganic liquid by utilizing the surface modification and activation technology of nanoparticles to form a uniform and stable non-Newtonian fluid sol system. The magnetic fluid not only has the surface effect, the small-size effect, the macroscopic quantum tunneling effect and the volume effect, but also has the characteristics of superparamagnetism, high magnetic susceptibility and the like. The research and application of the magnetic fluid are expanded from the original chemical material field to a plurality of fields of medicine, biochemistry, microelectronics, automatic control, optics and the like, a situation of multidisciplinary cross cooperation and common development is formed, and new properties and new performances of the magnetic fluid are continuously developed.

The market for seals and vacuum seals for dust protection is currently growing internationally. Nowadays, tens of millions of computers are installed in foreign countries, and disk drives of the computers adopt nano magnetic fluid dustproof sealing to ensure the ultra-pure state of the disk working environment. Vacuum sealing devices have also been used in semiconductor manufacturing equipment. In addition, large-scale integrated circuits, CVD equipment, plasma etching, vacuum deposition processes, and the like are sealed with a nanomagnetic fluid at a place where a high degree of vacuum must be maintained. In the pharmaceutical and chemical fields as well as in petrochemical production, there is a need for such a zero-leakage, contamination-free shaft seal arrangement. In 2008, China becomes the largest sealing element production base in the world, and 57.4% of sealing element products are produced in China all over the world. While the production of magnetic fluid seals is increasing at a rate of more than 15% per year. With the increasing production scale of the magnetic fluid sealing element, the performance requirement and the service life requirement of the magnetic fluid sealing element are increased. Chinese patent publication No. CN109686526A, a stable magnetic fluid under high magnetic field and a method for preparing the same, discloses a method for preparing a magnetic fluid, which comprises coating magnetic powder with a titanic acid coupling agent, mixing the magnetic powder, a carrier liquid and a dispersant, and performing ultrasonic dispersion to obtain the stable magnetic fluid. The magnetic saturation intensity of the magnetic fluid is 100-500 GS, but the magnetic fluid is unstable under the condition of a strong magnetic field of 1.26T, has low magnetic sedimentation resistance, and is not suitable for being used under the condition of the strong magnetic field of 1.26T.

Disclosure of Invention

The invention aims to solve the technical problem of low magnetic sedimentation resistance of the existing magnetic fluid, and provides a preparation method of a magnetic fluid for sealing with high magnetic sedimentation resistance under the condition of a strong magnetic field.

The preparation method of the magnetic fluid for high-magnetic-sedimentation-resistance sealing under the condition of the strong magnetic field comprises the following steps:

firstly, preparing Fe with the particle size of 5-20 nanometers₃O₄Magnetic powder:

secondly, weighing nano Fe₃O₄The lubricant comprises powder, a first antioxidant, a first dispersing agent, a second antioxidant, a second dispersing agent, a metal deactivator, a viscosity regulator and synthetic hydrocarbon base oil;

wherein the first antioxidant is barium petroleum sulfonate, dodecenylsuccinic acid, 4' -dioctyl diphenylamine, dodecenylsuccinic acid, zinc diisooctyl dithiophosphate or high-alkali sulfurized calcium alkyl phenolate;

the first dispersant is: polyisobutylene mono-succinimide, nonyl (octyl) phenol polyoxyethylene ether, diphenyl-p-isooctyl phosphate, sodium fatty alcohol polyoxyethylene ether sulfate, ashless polyisobutylene butylene diamide or alkenyl succinate;

the second antioxidant is octyl diphenylamine, β -mercaptopropionic acid, β -mercaptopropionic acid, trimethylhexadecylammonium bromide, alkylated diphenylamine or octylphenyl α naphthylamine;

the second dispersing agent is: polyvinyl n-butyl ether, boronated succinimide, sodium linear alkylbenzene sulfonate (LAS90), dialkyl dithiocarbamate, nonylphenol polyoxyethylene ether or high molecular weight polyisobutylene polysuccinimide;

III, according to nanometer Fe₃O₄The mass percentage concentration of the powder is 50-55 percent and the nano Fe₃O₄Adding the powder into cyclohexane, heating to 65-80 ℃ under the high-speed stirring condition of 4000-4500 rpm, adding a first dispersing agent and a first antioxidant, stirring for 10-20 minutes under the condition of 65-80 ℃, carrying out magnetic precipitation for 10-15 minutes, filtering by using filter cloth of 200-400 meshes, filtering out large particles and insoluble substances, and obtaining the surface-activated and modified nano Fe₃O₄Suspending the solution;

fourthly, activating and modifying the surface of the nano Fe₃O₄Adding the suspension solution into a reaction kettle with a circulating condensation system, adding heptane under the high-speed stirring condition with the rotating speed of 5000-6500 rpm, heating to 80-81 ℃, continuously stirring for 2-4 hours, and evaporating to remove cyclohexane to obtain nano Fe₃O₄A heptane dispersion of (1);

fifth, nanometer Fe in the reaction kettle₃O₄Adding a second dispersing agent and a second antioxidant into the heptane dispersion liquid, heating to 100-120 ℃, simultaneously starting a circulating water condensation system for reflux reaction for 1-2 hours, and cooling to room temperature to obtain secondary surface modified nano Fe₃O₄Magnetic powder-heptane pre-dispersion;

sixthly, adding the synthetic hydrocarbon base oil into a container, heating to 80-100 ℃, adding a metal passivator and a viscosity regulator under the high-speed stirring condition of 5000-6500 rpm, continuously stirring for 30-50 minutes, and then carrying out secondary surface modification on the nano Fe₃O₄Adding the magnetic powder-heptane pre-dispersion liquid into synthetic hydrocarbon base oil, simultaneously heating to 150-165 ℃, reacting for 2-4 hours under the high-speed stirring condition of 5000-6500 rpm, cooling to 100 ℃, placing a container on a magnet, and standing to room temperature to obtain the magnetic fluid with high magnetic sedimentation resistance under the condition of a strong magnetic field.

The invention firstly prepares Fe with the grain diameter of 5-20 nanometers₃O₄And making nano Fe₃O₄The lattice structure of the nano-Fe tends to be complete, thereby improving the nano-Fe₃O₄The specific saturation magnetization of the magnetic material is made to reach the original nano Fe₃O₄The specific saturation magnetization is 132 percent, so that the nano Fe is reduced₃O₄The solid content in a magnetic fluid system is reduced, and the nanometer F is reducede₃O₄Due to brownian motion. Then adding nano Fe₃O₄Surface modification and chemical bond coupling are carried out by using a dispersing agent and an antioxidant to ensure that the nano Fe₃O₄The surface is fully coated by the antioxidant, thereby leading the nano Fe₃O₄The metal oxide is completely isolated from the carrier liquid, and the damage of the metal oxide to the molecular structure of the carrier liquid is reduced. The secondary surface coating enhances the nano Fe₃O₄The lipophilicity and the intermolecular force solve the problem of nano Fe₃O₄The affinity problem with short-chain olefin is solved, a firmer chemical bond combination system is formed between the two, and the stable performance and structure of the sol system under the condition of strong magnetic field are realized. The invention not only reduces the cost of the product, but also solves the problems of high magnetic saturation intensity of the magnetic fluid and anti-magnetic sedimentation property of the product under the condition of strong magnetic field. The saturation magnetization B of the magnetic fluid is 498-570 GS, an anti-magnetic precipitation test is carried out under the condition of a 1.26T magnetic field at room temperature, no separation phenomenon occurs within 720 hours, and meanwhile, synthetic hydrocarbon base oil is used as carrier liquid, so that the heat resistance of the product is improved. The preparation method is simple in preparation process and easy to realize industrialization.

The invention adopts the nano ferrite soft magnetic material as the magnetic working medium, improves the surface activity and the functional coating technology, enhances the surface activation energy of the nano ferrite soft magnetic material, simultaneously improves the van der Waals force and intermolecular force of the nano ferrite soft magnetic material, further eliminates the force generated by gravity and a magnetic field on the nano ferrite soft magnetic material, forms a stable sol system under the condition of a strong magnetic field, and has high magnetic saturation strength. The high-vacuum degree sealing of the sealing element is realized by utilizing the unique magnetic film sealing property, no solid friction, high thermal conductivity, overlong stability, automatic memory repair, omnibearing sealing property and other excellent characteristics of the magnetic fluid; the system has high reliability, high transmission efficiency and high transmission speed; self-memory reparative; non-directional sealing and low energy consumption. The overall adaptability and application range of the sealing element are improved. The magnetic fluid can be widely applied to vacuum sealing and damping shock absorption, has good stability and high magnetic saturation intensity under the condition of a strong magnetic field, prolongs the service life of a sealing element and a shock absorber, ensures the stability of performance and enables the sealing element to achieve high vacuum degree sealing on a medium.

Drawings

FIG. 1 shows the nano Fe obtained in step one of example 1₃O₄XRD spectrum of (1);

FIG. 2 shows the nano-Fe obtained in step one of example 1₃O₄The particle size distribution map of (a);

FIG. 3 is a graph of the specific magnetic saturation intensity of the magnetic fluid prepared in example 1;

FIG. 4 is a photograph of a magnetic sedimentation resistance test of the magnetic fluid prepared in example 1;

FIG. 5 shows the nano-Fe obtained in step one of example 2₃O₄XRD spectrum of (1);

FIG. 6 shows the nano-Fe obtained in step one of example 2₃O₄The particle size distribution map of (a);

FIG. 7 is a graph of the specific magnetic saturation intensity of the magnetic fluid prepared in example 2;

FIG. 8 is a photograph of a magnetic sedimentation resistance test of the magnetic fluid prepared in example 2;

FIG. 9 shows the nano-Fe obtained in step one of example 3₃O₄XRD spectrum of (1);

FIG. 10 shows the nano-Fe obtained in step one of example 3₃O₄The particle size distribution map of (a);

FIG. 11 is a graph of the specific magnetic saturation intensity of the magnetic fluid prepared in example 3;

FIG. 12 is a photograph of a magnetic sedimentation resistance test of the magnetic fluid prepared in example 3;

FIG. 13 shows the nano-Fe obtained in step one of example 4₃O₄XRD spectrum of (1);

FIG. 14 shows the nano-Fe obtained in step one of example 4₃O₄The particle size distribution map of (a);

FIG. 15 is a graph of the specific magnetic saturation intensity of the magnetic fluid prepared in example 4;

FIG. 16 is a photograph of a magnetic sedimentation resistance test of the magnetic fluid prepared in example 4;

FIG. 17 shows the nano-Fe obtained in step one of example 5₃O₄XRD spectrum of (1);

FIG. 18 shows the nano-Fe obtained in step one of example 5₃O₄The particle size distribution map of (a);

FIG. 19 is a graph of the specific magnetic saturation intensity of the magnetic fluid prepared in example 5;

FIG. 20 is a photograph of a magnetic sedimentation resistance test of the magnetic fluid prepared in example 5;

FIG. 21 shows the nano-Fe obtained in step one of example 6₃O₄XRD spectrum of (1);

FIG. 22 shows the nano-Fe obtained in step one of example 6₃O₄The particle size distribution map of (a);

FIG. 23 is a graph of the specific magnetic saturation intensity of the magnetic fluid prepared in example 6;

FIG. 24 is a photograph of a magnetic sedimentation resistance test of the magnetic fluid prepared in example 6.

Detailed Description