Preparation method of nano zinc oxide

Abstract

The invention discloses a preparation method of nano-zinc oxide, and relates to the technical field of preparation of nano-zinc oxide. The method comprises the following steps: mixing zinc oxide powder with a selenium-containing compound water phase, combining the synergistic effect of an antioxidant stabilizer with a specific structure and an inorganic ligand mixture (titanium dioxide, calcium carbonate, white carbon black and talcum powder), and carrying out pH regulation and control, wet grinding and segmented calcination under nitrogen protection to prepare the high-stability nano zinc oxide. Through selenium doping and a heteroatom chelation mechanism of the anti-oxidation stabilizer, an electron trap and a physical barrier for inhibiting an oxidation reaction are formed; the inorganic ligand realizes size control and dispersion stability of the nanoparticles through a heterogeneous nucleation template effect and a surface adsorption effect; the segmented calcination process optimizes crystal growth kinetics and reduces lattice defects. And the obtained product is obviously superior to the traditional process in the aspects of oxidation resistance, dispersion uniformity and high-temperature stability.

Description

Technical Field

[0001] The present invention relates to the technical field of nano zinc oxide preparation, and in particular to a method for preparing nano zinc oxide. Background Art

[0002] Nano-zinc oxide (ZnO) is increasingly used in modern industry and technology due to its unique advantages. It plays a key role in applications ranging from rubber manufacturing to optical materials, from electronic devices to biomedicine. However, existing preparation methods have numerous stability issues and urgently need improvement.

[0003] Traditional preparation processes, such as direct precipitation, are easy to operate and low in cost, but the resulting nano zinc oxide particles are prone to agglomeration. Nano zinc oxide prepared by methods such as chemical precipitation and sol-gel methods can perform well under specific conditions and in some application fields. However, its stability is still insufficient when faced with complex industrial applications and harsh environments. For example, in electronic devices, nano zinc oxide needs to work stably for a long time under different temperature, humidity and electric field conditions, which traditional processes cannot meet. Nano zinc oxide prepared by spray pyrolysis and hydrothermal methods faces challenges in large-scale industrial production. The production process is difficult to control precisely, and is prone to problems such as uneven particle size distribution and fluctuations in impurity content, resulting in unstable product quality. This not only affects the performance consistency in subsequent applications, but also increases production costs, limiting its in-depth application in high-end fields.

[0004] Furthermore, most traditional preparation methods neglect antioxidant properties. In actual use, nano zinc oxide is easily oxidized, resulting in performance degradation, shortened service life, and impacting the reliability and long-term effectiveness of related products and systems, making it difficult to meet the stringent requirements of modern industry for material stability. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing zinc oxide with high stability, strong oxidation resistance and good nano-dispersion in order to solve the problems existing in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing nano zinc oxide, comprising the following steps:

[0007] S1. The zinc oxide powder and the selenium-containing compound are added to water and stirred to obtain a mixed material;

[0008] S2. A precipitant was added to the mixture to adjust the pH of the solution to 8-11 to obtain a precursor suspension;

[0009] S3. The antioxidant stabilizer, titanium dioxide, calcium carbonate, white carbon black, talc are stirred and mixed in proportion to obtain an inorganic ligand mixture;

[0010] S4. The inorganic ligand mixture described in S3 is added to the precursor suspension described in S2, stirred at a constant temperature of 60-90 ° C for 1-4 hours, followed by wet grinding to obtain a mixed dispersion;

[0011] S5. The mixed dispersed material described in S4 is sequentially subjected to solid-liquid separation, deionized water washing, vacuum drying and staged calcination to obtain a nano zinc oxide;

[0012] The structure of the antioxidant stabilizer is as shown in Formula 1:

[0013]

[0014] The Z1 is selected from: O, S, N(H), C(CH3)2.

[0015] Furthermore, the selenium-containing compound is selected from at least one of sodium selenite, selenium powder or selenium dioxide. Furthermore, the antioxidant stabilizer is selected from any one of the compounds shown in the following structures:

[0016] Furthermore, the synthesis method of the antioxidant stabilizer is:

[0017]

[0018] Step 1: Raw materials 1 and 2 undergo Suzuki coupling reaction to generate intermediate 1;

[0019] Step 2: Intermediate 1 undergoes borylation reaction to generate intermediate 2;

[0020] Step 3: Intermediate 2 and raw material 3 are subjected to Suzuki coupling reaction to generate antioxidant stabilizer.

[0021] Furthermore, the precipitant is selected from at least one of sodium hydroxide, sodium carbonate, ammonia water or urea.

[0022] Furthermore, the inorganic ligand mixture comprises the following components by mass: 10-25 parts of titanium dioxide, 15-30 parts of calcium carbonate, 5-15 parts of white carbon black, 20-40 parts of talc, and 3-6 parts of antioxidant stabilizer.

[0023] Furthermore, the wet grinding process uses a planetary ball mill, the grinding medium is zirconia balls, the grinding time is 2-6 hours, and the solid content of the slurry is controlled at 30-50%.

[0024] Furthermore, the staged calcination treatment is specifically as follows: firstly heating to 150-200°C at 2-5°C / min and keeping the temperature for 1-2 hours, then heating to 250-300°C at 3-8°C / min and calcining for 2-3 hours.

[0025] Furthermore, the mass ratio of the zinc oxide powder, the selenium-containing compound and the inorganic ligand mixture is 100:1.5:(25-30).

[0026] Furthermore, the vacuum drying conditions are: vacuum degree -0.08 to -0.1 MPa, drying temperature 60-80° C., and drying time 4-8 hours.

[0027] Furthermore, the staged calcination treatment is carried out in a nitrogen atmosphere, and after calcination, the calcination is cooled to room temperature at a rate of 1-5°C / min.

[0028] The heteroatoms (e.g., O and N) in the antioxidant stabilizer core of the present invention can bind to the zinc oxide surface, inhibiting active oxidation sites. The conjugated structure may capture free radicals through delocalized electrons, blocking the oxidation chain reaction. The rigid core structure forms a physical barrier on the nanoparticle surface, reducing oxygen exposure.

[0029] The present invention synergizes selenium-containing compounds (such as sodium selenite) with selenium-doped zinc oxide to form electron traps in the lattice to inhibit oxidative activity; antioxidant stabilizers block oxidative chain reactions through heteroatom chelation and spatial shielding effects; in the inorganic ligand mixture, titanium dioxide acts as a heterogeneous nucleation template to regulate crystal growth, the porous structure generated by the calcination of calcium carbonate improves dispersibility, and white carbon black and talc synergistically inhibit particle agglomeration through surface adsorption and layered isolation; combined with wet grinding (high-energy crushing of zirconia balls) and a staged calcination process under a nitrogen atmosphere (low-temperature dehydration-high-temperature crystallization gradient control), a multi-level protection system of "selenium-doped modified strong core + inorganic ligand coating + thermodynamically stable structure" is synergistically constructed, ultimately achieving high stability, antioxidant properties and uniform dispersion characteristics of nano zinc oxide.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. Significantly improved stability: Through the synergistic effect of selenium doping and multi-level coating system, the oxidative degradation and high-temperature agglomeration of nanoparticles are effectively inhibited, showing better chemical stability in complex application environments.

[0032] 2. Enhanced antioxidant performance: Antioxidant stabilizers significantly reduce the oxidation rate of active sites on the surface of zinc oxide through the dual mechanisms of electron capture and physical barrier, thereby extending the service life of the material.

[0033] 3. Improved dispersibility and homogenization: The template control of the inorganic ligand mixture is combined with the wet grinding process to significantly reduce particle aggregation, achieve a more uniform particle size distribution and a more stable dispersion state, and adapt to the needs of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1The invention discloses a method for synthesizing the antioxidant stabilizer. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Synthesis example 1

[0037] Synthesis of antioxidant stabilizer 1:

[0038]

[0039] Step 1: Under a nitrogen atmosphere, 20 g of raw material 1, 20.40 g of raw material 2, 16.93 g of anhydrous potassium carbonate, 2.13 g of tetrakis(triphenylphosphine)palladium and 200 g of a mixed solution of toluene, ethanol and water (volume ratio 2:1:1) were added to the reaction system in sequence, heated to 95 ° C and refluxed for 10 hours, turned off the heating, cooled to room temperature, and allowed to stand for separation. The aqueous phase was extracted twice with ethyl acetate, the organic phases were combined, washed three times with water, spin-dried, and column chromatography was performed using a mixture of petroleum ether and dichloromethane as an eluent to obtain 21.87 g of intermediate 1.

[0040] Step 2: Under a nitrogen atmosphere, 21.87 g of intermediate 1 and 210 g of ultra-dry tetrahydrofuran were added to the reaction system in sequence, and the temperature was lowered to -70°C. 3.08 g of n-butyl lithium was added dropwise, and the mixture was stirred for 1 h. 12.90 g of triisopropyl borate was added dropwise. After the addition was complete, the mixture was naturally warmed to room temperature and reacted for 10 h. The solvent was then dried to obtain 15.10 g of intermediate 2.

[0041] Step 3: Under a nitrogen atmosphere, 15.10 g of intermediate 2, 20.25 g of raw material 3, 9.42 g of anhydrous potassium carbonate, 1.18 g of tetrakis(triphenylphosphine)palladium, and 200 g of a mixed solution of toluene, ethanol, and water (volume ratio of 2:1:1) were added sequentially to the reaction system. The mixture was heated at 95°C under reflux for 10 hours. The heat was turned off, the mixture was cooled to room temperature, and the mixture was allowed to stand for separation. The aqueous phase was extracted twice with ethyl acetate. The organic phases were combined, washed three times with water, and dried by spin drying. The mixture was then purified by column chromatography using a mixture of petroleum ether and dichloromethane as the eluent to obtain 21.72 g of antioxidant stabilizer 1. MS [MS+1]: 814.

[0042] Antioxidant stabilizer 1 1HNMR-deuterated chloroform: δ8.44-8.32 (m, 4H), 8.21-8.10 (m, 3H), 7.89 (dd, 1H), 7.74 (dd, 1H), 7.66-7.41 (m, 14H), 7.28 (s, 1H), 7.20-7.13 (m, 1H), 4.08 (t, 2H), 0.98 (s, 9H), 0.24 (s, 6H).

[0043] Synthesis Example 2-Synthesis Example 4

[0044] The synthesis of antioxidant stabilizer 2-4 was carried out according to the method of Synthesis Example 1, except that raw material 1 was replaced. The rest of the synthesis remained the same as in Synthesis Example 1. The specific structure of raw material 1, the structure of antioxidant stabilizer 2-4, and the MS [MS+1] data are shown in the table below.

[0045]

[0046]

[0047] Example 1

[0048] A method for preparing nano zinc oxide, the specific steps are as follows:

[0049] S1. Weigh 100 parts by mass of zinc oxide powder (average particle size 1.5 μm) and 1.5 parts by mass of sodium selenite (selenium-containing compound), add them to 500 mL of deionized water, and stir at 800 rpm for 30 minutes to obtain a uniform mixture.

[0050] S2. Add 10 wt % sodium hydroxide solution (precipitant) dropwise to the mixture, adjust the pH of the system to 9.5 ± 0.2, and continue stirring for 1 hour to form a milky white precursor suspension.

[0051] S3. Weigh, by mass, the following: 15 parts of titanium dioxide (anatase type, 50 nm particle size), 22 parts of calcium carbonate (light calcium carbonate, 800 nm particle size), 10 parts of white carbon black (fumed SiO2), 30 parts of talc, and 14 parts of the antioxidant stabilizer prepared in Synthesis Example 1. Add these ingredients to a V-type mixer and mix at 60 rpm for 45 minutes to obtain a uniform inorganic ligand mixture.

[0052] S4. Slowly add 27.5 parts by weight of the inorganic ligand mixture to the precursor suspension. Control the system temperature at 75±2°C and stir at 1200 rpm for 2.5 hours. Then transfer the mixture to a planetary ball mill using 3 mm diameter zirconia balls as the grinding medium. Adjust the slurry solids content to 40% and mill at 300 rpm for 4 hours to obtain a nanoscale mixed dispersion.

[0053] S5: Filter the mixed dispersed material through a plate and frame filter press to collect the filter cake; wash the filter cake with 60°C deionized water until the conductivity is less than 50μS / cm; place the filter cake in a vacuum drying oven (-0.09MPa) and dry it at 70°C for 6 hours to obtain a dry powder with a moisture content of less than 1%; load the powder into a tubular furnace under a nitrogen atmosphere: first stage: heat to 180°C at 3°C / min and keep warm for 1.5 hours; second stage: heat to 280°C at 5°C / min and calcine for 2.5 hours; cooling stage: cool to room temperature at 3°C / min to obtain the finished nano zinc oxide product.

[0054] Example 2-Example 4

[0055] Referring to the preparation method of nano zinc oxide in Example 1, the antioxidant stabilizer therein was replaced with the antioxidant stabilizers prepared in Synthesis Examples 2 to 4 in sequence, and the rest remained the same as in Example 1.

[0056] Comparative Example 1

[0057] Referring to the preparation method of nano zinc oxide in Example 1, the antioxidant stabilizer is not added, and the rest remains the same as in Example 1.

[0058] Comparative Example 2

[0059] Referring to the preparation method of nano zinc oxide in Example 1, the mass parts of zinc oxide powder were replaced with 80 parts, and the rest remained the same as in Example 1.

[0060] Performance testing:

[0061] The zinc oxide content was detected according to standard Q / RB-017-2017, the average particle size was measured using a laser particle size analyzer, and the specific surface area was measured using a specific surface area meter.

[0062] Average particle size / μm <![CDATA[Specific surface area / m 2 / g]]> Zinc oxide content / % Example 1 0.75 28 52.2 Example 2 0.76 33 53.8 Example 3 0.67 29 51.1 Example 4 0.88 26 49.5 Comparative Example 1 1.02 21 32.3 Comparative Example 2 0.95 22 38.7

[0063] Compared with the comparative example, the nano zinc oxide in the embodiment shows a better trend in terms of the three indicators of average particle size, specific surface area and zinc oxide content. The embodiments in which an antioxidant stabilizer is added generally show a smaller average particle size and a higher specific surface area, indicating that the component effectively suppresses particle agglomeration and promotes dispersion. In contrast, in comparative example 1 in which no stabilizer is added and comparative example 2 in which the raw material ratio is adjusted, the average particle size is significantly increased, the specific surface area is significantly reduced, and the zinc oxide content is greatly reduced, reflecting the key influence of the synergistic effect of the antioxidant stabilizer and the raw material ratio on the product performance. The differences between the different embodiments show that the structural changes of the antioxidant stabilizer will directly affect the particle size distribution and zinc oxide purity of the final product, wherein the stabilizer of a specific structure has more advantages in suppressing oxidation and maintaining the nanostructure.

[0064] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing nano zinc oxide, characterized in that: The following steps are involved: S1. The zinc oxide powder and the selenium-containing compound are added to water and stirred to obtain a mixed material; S2. A precipitant was added to the mixture to adjust the pH of the solution to 8-11 to obtain a precursor suspension; S3. The antioxidant stabilizer, titanium dioxide, calcium carbonate, white carbon black, talc are stirred and mixed in proportion to obtain an inorganic ligand mixture; S4. The inorganic ligand mixture described in S3 is added to the precursor suspension described in S2, stirred at a constant temperature of 60-90 ° C for 1-4 hours, followed by wet grinding to obtain a mixed dispersion; S5. The mixed dispersed material described in S4 is sequentially subjected to solid-liquid separation, deionized water washing, vacuum drying and staged calcination to obtain a nano zinc oxide; The structure of the antioxidant stabilizer is as shown in Formula 1: The Z1 is selected from: O, S, N(H), C(CH3)2.

2. The method for preparing nano zinc oxide according to claim 1, wherein: The selenium-containing compound is selected from at least one of sodium selenite, selenium powder or selenium dioxide.

3. The method for preparing nano zinc oxide according to claim 1, wherein: The antioxidant stabilizer is selected from any one of the compounds shown in the following structures:

4. The method for preparing nano zinc oxide according to claim 1, wherein: The precipitant is selected from at least one of sodium hydroxide, sodium carbonate, ammonia water or urea.

5. The method for preparing nano zinc oxide according to claim 1, wherein: The inorganic ligand mixture comprises the following components by mass: 10-25 parts of titanium dioxide, 15-30 parts of calcium carbonate, 5-15 parts of white carbon black, 20-40 parts of talc, and 3-6 parts of antioxidant stabilizer.

6. The method for preparing nano zinc oxide according to claim 1, wherein: The wet grinding process uses a planetary ball mill, the grinding medium is zirconia balls, the grinding time is 2-6 hours, and the solid content of the slurry is controlled at 30-50%.

7. The method for preparing nano zinc oxide according to claim 1, wherein: The staged calcination treatment is specifically as follows: firstly heating the temperature to 150-200°C at 2-5°C / min and keeping the temperature for 1-2 hours, then heating the temperature to 250-300°C at 3-8°C / min and calcining for 2-3 hours.

8. The method for preparing nano zinc oxide according to claim 1, wherein: The mass ratio of the zinc oxide powder, the selenium-containing compound and the inorganic ligand mixture is 100:1.5:(25-30).

9. The method for preparing nano zinc oxide according to claim 1, wherein: The vacuum drying conditions are: vacuum degree -0.08 to -0.1 MPa, drying temperature 60-80° C., and drying time 4-8 hours.

10. The method for preparing nano zinc oxide according to claim 1, wherein: The stepwise calcination process is carried out under a nitrogen atmosphere, and after calcination, the product is cooled to room temperature at a rate of 1-5° C. / min.

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