Surface-modified silicon micropowder and method for preparing the same

Abstract

The application discloses surface-modified silicon powder and a preparation method thereof, and comprises the following components in proportion by weight: 88-92 parts of silicon powder, 3-5 parts of self-made starch-based coupling agent, 2-3 parts of aluminate coupling agent, 1-2 parts of nano-silicon dioxide-polydopamine composite particles and 1-2 parts of dispersing agent. The application belongs to the technical field of surface-modified silicon powder, and particularly relates to surface-modified silicon powder and a preparation method thereof.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of surface modified silicon micro powder, and particularly relates to a surface modified silicon micro powder and a preparation method thereof. BACKGROUND

[0002] As an important inorganic non-metallic material, silicon micro powder has a wide application in many fields such as electronics, chemical industry and building materials due to its high hardness, high insulation, low thermal expansion coefficient and other excellent performances. However, the surface of untreated silicon micro powder contains a large number of hydroxyl groups, and the surface energy is high, so the silicon micro powder is easy to agglomerate in an organic matrix and has poor compatibility with the matrix, which greatly limits the application of the silicon micro powder in high-performance composite materials.

[0003] Traditional modification methods of silicon micro powder mostly use a single type of coupling agent, which can improve the interface bonding between the silicon micro powder and the matrix to a certain extent, but can only improve a certain aspect of performance, such as dispersibility or compatibility with a specific type of matrix. Moreover, some traditional coupling agents have problems such as high cost and poor environmental friendliness. With the increasing requirements of modern industry on the performance of materials, such as the need for good dispersibility, high thermal stability and strong bonding force with the matrix in electronic packaging materials, and the need for good processability and environmental friendliness of materials in environmentally friendly coatings, it has become an urgent problem to develop a new type of surface modified silicon micro powder with multiple excellent performances and high cost performance. SUMMARY

[0004] In order to solve the above problems, the application provides a new type of surface modified silicon micro powder with multiple excellent performances and high cost performance and a preparation method thereof.

[0005] In order to achieve the above functions, the technical scheme adopted by the application is as follows: a surface modified silicon micro powder and a preparation method thereof, which comprises the following components by weight fraction: 88-92 parts of silicon micro powder, 3-5 parts of self-made starch-based coupling agent, 2-3 parts of aluminate coupling agent, 1-2 parts of nano-silica-polydopamine composite particles and 1-2 parts of dispersant.

[0006] Preferably, the average particle size of the silicon micro powder is 8-20 microns, and the silica content is greater than or equal to 98%.

[0007] Preferably, the preparation method of the nano-silica-polydopamine composite particles is as follows:

[0008] a: Pour the nano-silica colloidal solution into a reaction container, add a tris-hydrochloric acid buffer solution to the nano-silica colloidal solution for mixing, and the volume ratio of the two solutions is 1-2 times, so that the PH is between 8 and 9, to obtain a mixture.

[0009] b. Adding dopamine monomer to the mixture, the mass ratio of dopamine monomer to nano-silicon dioxide is between 0.5:1-2:1, stirring the mixture at 200-500 revolutions per minute for 12-24 hours to obtain a reactant

[0010] Preferably, the preparation method of the self-made starch-based coupling agent is as follows: starch and water are mixed in a ratio of 1:2 to 1:1.5 to form a starch milk, the starch milk is heated at a temperature of 60-80℃ for 30 minutes to 1 hour to gelatinize the starch, and then the gelatinized starch is cooled to room temperature, 10%-30% of the amount of maleic anhydride is added, and then 1%-5% of the amount of sodium hydroxide is added, and the temperature is maintained at 40-60℃ during stirring, and stirring is performed for 3-6 hours to form a starch-based coupling agent, which is then cooled to room temperature, washed with ethanol, and dried to obtain the self-made starch-based coupling agent.

[0011] Preferably, the dispersant is sodium lignosulfonate.

[0012] The application further discloses a preparation method of surface-modified silicon powder.

[0013] S1: Silicon powder pretreatment: the silicon powder is placed in a blast drying oven and dried at 100-110℃ for 3-4 hours to remove water and a small amount of volatile impurities, so that the silicon powder is in a dry state, which is beneficial to the subsequent modification reaction.

[0014] S2: Preparation of a composite modifier solution: the self-made starch-based coupling agent, the aluminate coupling agent and the dispersant are mixed and dissolved to prepare a composite modifier solution.

[0015] S3: Surface modification reaction: the pretreated silicon powder is added to a three-necked flask at an addition rate of 5-10g / min, and the stirring speed is increased to 600-800r / min; the composite modifier is fully contacted with the surface of the silicon powder and reacts at 70-80℃ for 2-3 hours, and in the reaction process, reflux is performed through a condenser tube to reduce solvent volatilization.

[0016] S4: Post-treatment: after the reaction is completed, the reaction product is filtered to obtain a solid product, the solid product is washed with deionized water for 3-4 times, each time using water in an amount of 2-3 times the mass of the solid product to remove unreacted modifiers and impurities, and the washed solid product is dried in a vacuum drying oven at 60-70℃ for 3-4 hours to obtain a surface-modified silicon powder product.

[0017] Preferably, the preparation of the composite modifier solution in the S2 step comprises the following steps:

[0018] a: In a three-necked flask with a stirrer and a thermometer, add self-made starch-based coupling agent, aluminate coupling agent and dispersant;

[0019] b: Add an appropriate amount of anhydrous ethanol as a solvent, and the amount of ethanol is 8-10 times the total mass of the composite modifier;

[0020] c: Stir at room temperature at a speed of 200-300 r / min for 10-15 minutes to preliminarily mix the components uniformly, and then slowly heat to 50-60℃, and continue to stir for 20-30 minutes;

[0021] d step: Add nano-silicon dioxide-polydopamine composite particles to the above solution, and ultrasonically treat for 15-20 minutes at an ultrasonic power of 400-600W to uniformly disperse the composite particles in the solution.

[0022] The present application adopts the above structure and achieves the following beneficial effects: A variety of modifiers can form a bonding or adsorption layer on the surface of the silicon powder, enhancing the compatibility with the organic matrix and improving the mechanical properties of the material. The dispersant and fine process ensure good and stable dispersion of the silicon powder in the system, avoiding problems such as uneven product performance and coating defects. The nano-silicon dioxide-polydopamine composite particles bring special properties such as oxidation resistance and antibacterial properties, and have application potential in the field of functional materials. The self-made starch-based coupling agent and sodium lignosulfonate are environmentally friendly and low in cost, which is conducive to industrialization and sustainable development. The problems of hydrophilicity and easy agglomeration of the silicon powder are solved, and the hydrophobicity and chemical stability are improved, which is suitable for different application environments. DETAILED DESCRIPTION

[0023] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0024] Example 1:

[0025] A surface-modified silicon powder, which comprises the following components by weight fraction: silicon powder: 88 parts (average particle size 8 μm, silicon dioxide content 98.3%), self-made starch-based coupling agent: 3 parts, aluminate coupling agent: 2 parts, nano-silicon dioxide-polydopamine composite particles: 1 part, sodium lignosulfonate: 1 part.

[0026] The application further discloses a preparation method of the surface-modified silicon powder.

[0027] S1: silicon powder pretreatment: the silicon powder is placed in a blast drying oven and dried at 100 DEG C for 4 hours;

[0028] S2: preparation of a composite modifier solution:

[0029] a step: in a three-necked flask with a stirrer and a thermometer, 3 parts of the self-made starch-based coupling agent, 2 parts of the aluminate coupling agent and 1 part of the dispersant are added;

[0030] b step: 48 parts of (3+2+1) * 8 anhydrous ethanol are added as a solvent;

[0031] c step: stirring is carried out at a rotation speed of 200 r / min for 15 minutes at room temperature, and then the temperature is slowly increased to 50 DEG C, and stirring is continuously carried out for 30 minutes;

[0032] d step: 1 part of the nano-silicon dioxide-polydopamine composite particle is added into the above solution, and ultrasonic treatment is carried out under the condition that the ultrasonic power is 400 W for 20 minutes.

[0033] S3: surface modification reaction: the pretreated silicon powder is added into the three-necked flask at a speed of 5 g / min, meanwhile, the stirring rotation speed is increased to 600 r / min, and reaction is carried out at 70 DEG C for 3 hours, and reflux is carried out through a condenser.

[0034] S4: post-treatment: after the reaction is completed, the solid product is obtained through filtration, the solid product is washed with deionized water, the water amount is about 176 parts (the solid product quality is about 88 parts, 2 times) each time, the washing is carried out 4 times, and the washed solid product is dried in a vacuum drying oven at 60 DEG C for 4 hours.

[0035] Example 2:

[0036] A surface-modified silicon powder, which comprises the following components in parts by weight: silicon powder: 90 parts (average particle size 15 microns, silicon dioxide content 98.5%), self-made starch-based coupling agent: 4 parts, aluminate coupling agent: 2.5 parts, nano-silicon dioxide-polydopamine composite particle: 1.5 parts, sodium lignosulfonate: 1.5 parts.

[0037] The application further discloses a preparation method of the surface-modified silicon powder, which comprises the following steps:

[0038] S1: silicon powder pretreatment: the silicon powder is placed in a blast drying oven and dried at 105 DEG C for 3.5 hours.

[0039] S2: Preparation of a composite modifier solution:

[0040] a Step: Add 4 parts of self-made starch-based coupling agent, 2.5 parts of aluminate coupling agent and 1.5 parts of dispersant in a three-necked flask with a stirrer and a thermometer;

[0041] b Step: Add 72 parts of anhydrous ethanol as a solvent ((4 + 2.5 + 1.5) x 9);

[0042] c Step: Stir at a speed of 250 r / min for 12 minutes at room temperature, and then slowly heat to 55℃, continue to stir for 25 minutes;

[0043] d Step: Add 1.5 parts of nano-silicon dioxide-polydopamine composite particles to the above solution, and ultrasonic treat for 18 minutes under the condition of ultrasonic power of 500W.

[0044] S3: Surface modification reaction: add the pretreated silicon powder into the three-necked flask at a speed of 8g / min, and increase the stirring speed to 700r / min, react at 75℃ for 2.5 hours, and reflux through the condenser tube.

[0045] S4: Post-treatment: after the reaction is completed, filter to obtain a solid product, wash the solid product with deionized water, the amount of water used each time is about 200 parts (the mass of the solid product is about 100 parts, 2 times), wash for 3 times, and dry the washed solid product in a vacuum drying oven at 65℃ for 3.5 hours.

[0046] Example 3:

[0047] A surface modified silicon powder, which comprises the following components in parts by weight: silicon powder: 92 parts (average particle size 20μm, silicon dioxide content 98.8%), self-made starch-based coupling agent: 5 parts, aluminate coupling agent: 3 parts, nano-silicon dioxide-polydopamine composite particles: 2 parts, sodium lignosulfonate: 2 parts.

[0048] The application also discloses a preparation method of the surface modified silicon powder, which comprises the following steps:

[0049] S1: Silicon powder pretreatment: place the silicon powder in a blast drying oven and dry at 110℃ for 3 hours.

[0050] S2: Preparation of a composite modifier solution:

[0051] a Step: Add 4 parts of self-made starch-based coupling agent, 2.5 parts of aluminate coupling agent and 1.5 parts of dispersant in a three-necked flask with a stirrer and a thermometer;

[0052] b Step: 90 parts of anhydrous ethanol were added as a solvent;

[0053] c Step: stirring at room temperature at a speed of 300 r / min for 10 minutes, and then slowly increasing the temperature to 60°C, and continuing to stir for 20 minutes;

[0054] d Step: 2 parts of nano-silicon dioxide-polydopamine composite particles were added to the above solution, and ultrasonic treatment was performed under the condition of an ultrasonic power of 600 W for 15 minutes.

[0055] S3: surface modification reaction: the pretreated silicon powder was added to a three-necked flask at a speed of 10 g / min, and the stirring speed was increased to 800 r / min, and the reaction was carried out at 80°C for 2 hours, and the reflux was carried out through a condenser.

[0056] S4: post-treatment: after the reaction was completed, the solid product was obtained by filtration, and the solid product was washed with deionized water, and the amount of water used each time was about 276 parts (the mass of the solid product was about 138 parts, 2 times), and the washing was carried out 3 times, and the washed solid product was dried in a vacuum drying oven at 70°C for 3 hours.

[0057] Results data analysis:

[0058] Example Dispersion (visual observation, rating 1 - 5, 5 best) Contact angle (°) Specific surface area (m² / g) Bulk density (g / cm³) Particle size distribution uniformity (standard deviation, the smaller the more uniform) Surface active group content (mmol / g) Thermal stability (onset decomposition temperature, °C) 1 3 120 2.5 1.2 0.8 1.5 350 2 4 135 3.2 1.1 0.5 2.2 400 3 3.5 130 3 1.15 0.6 2 380

[0059] In terms of dispersibility, example 2 reached level 4, which was significantly better than level 3 of example 1 and level 3.5 of example 3, indicating that it was well dispersed in the medium, which was due to the appropriate component ratio and moderate particle size of the silicon powder, so that the agglomeration between particles was effectively inhibited.

[0060] The contact angle data showed that the 135° of example 2 was higher than the 120° of example 1 and the 130° of example 3, indicating that it had better hydrophobicity, and various modifiers synergistically acted under suitable conditions to form a more optimal hydrophobic structure on the surface of the silicon powder.

[0061] In terms of specific surface area, the 3.2 m² / g of example 2 was higher than the 2.5 m² / g of example 1 and the 3.0 m² / g of example 3, and more specific surface area meant more active sites, which was beneficial to the interaction with other materials, which was attributed to good dispersibility and effective surface modification.

[0062] In terms of bulk density, 1.1 g / cm3 of Example 2 is lower than 1.2 g / cm3 of Example 1 and 1.15 g / cm3 of Example 3, and lower bulk density is beneficial to achieve more uniform distribution in filling applications.

[0063] The standard deviation data of particle size distribution uniformity show that 0.5 of Example 2 is less than 0.8 of Example 1 and 0.6 of Example 3, that is, the particle size distribution uniformity of Example 2 is better, which can ensure the stability of material performance.

[0064] In terms of surface active group content, 2.2 mmol / g of Example 2 is higher than 1.5 mmol / g of Example 1 and 2.0 mmol / g of Example 3, and more active groups provide sufficient sites for reaction or adsorption with other materials.

[0065] In terms of thermal stability, the initial decomposition temperature of 400℃ of Example 2 is higher than 350℃ of Example 1 and 380℃ of Example 3, which shows better thermal stability, which is due to perfect surface modification and good dispersibility.

[0066] In summary, the parameter combination of Example 2 can make the silicon powder reach the best comprehensive performance, which is more in line with the requirements of high-performance surface-modified silicon powder.

[0067] The above describes the present application and its embodiments, which is not restrictive. In general, if a person skilled in the art is inspired by it, without departing from the purpose of the present application, without creative design, similar structural ways and embodiments to the technical solution should belong to the protection scope of the present application.

Claims

1. A surface-modified silica powder, characterized in that... The composition by weight includes the following components: silica powder: 88-92 parts; self-made starch-based coupling agent: 3-5 parts; aluminate coupling agent: 2-3 parts; nano-silica-polydopamine composite particles: 1-2 parts; and dispersant: 1-2 parts, wherein the dispersant is sodium lignosulfonate. It also includes a method for preparing the aforementioned nano-silica-polydopamine composite particles, as follows: a. Pour the nano-silica gel solution into a reaction vessel, add tris(hydroxymethyl)aminomethane (Tris)-hydrochloric acid buffer solution to the nano-silica gel solution and mix, with the volume ratio of the two solutions being 1-2 times, so that the pH is between 8 and 9, to obtain a mixture; b. Add dopamine monomer to the mixture, with the mass ratio of dopamine monomer to nano-silica between 0.5:1 and 2:1, and stir at 200-500 rpm for 12-24 hours to obtain the reactant; c. Centrifuge the reactants and products at a speed of 5000-10000 rpm for 5-10 minutes to remove unreacted dopamine monomers, impurities in the buffer solution, and other byproducts that may be formed during the reaction. d. Wash the reaction product with deionized water to further remove residual reactants and impurities, and then dry it to obtain nano-silica-polydopamine composite particles; The preparation method of the self-made starch-based coupling agent is as follows: starch and water are mixed in a ratio of 1:2 to 1:1.5 to form a starch slurry. The starch slurry is heated to a temperature between 60 and 80°C for 30 minutes to 1 hour to fully gelatinize the starch. After the gelatinized starch is cooled to room temperature, 10% to 30% of maleic anhydride based on the starch weight is added and mixed. Then, 1% to 5% of sodium hydroxide based on the starch weight is added. During the stirring process, the temperature is maintained between 40°C and 60°C for 3 to 6 hours to form a starch-based coupling agent. After cooling to room temperature, it is washed with ethanol and dried. The dried product is the self-made starch-based coupling agent.

2. The surface-modified silica powder according to claim 1, characterized in that, The average particle size of the silicon micropowder is 8-20 μm, and its silicon dioxide content is ≥98%.

3. A method for preparing surface-modified silica micropowder according to any one of claims 1 to 2, characterized in that: Includes the following steps: S1: Pretreatment of silicon micro powder: Place the silicon micro powder in a forced-air drying oven and dry it at 100-110℃ for 3-4 hours to remove moisture and a small amount of volatile impurities, so that the silicon micro powder is in a dry state, which is beneficial to the subsequent modification reaction; S2: The preparation steps of the composite modifier solution include: a: In a three-necked flask equipped with a stirrer and a thermometer, add the homemade starch-based coupling agent, aluminate coupling agent and dispersant; b: Add an appropriate amount of anhydrous ethanol as a solvent. The amount of ethanol is 8-10 times the total mass of the composite modifier. c: Stir at 200-300 rpm for 10-15 minutes at room temperature to ensure initial uniform mixing of all components, then slowly heat to 50-60℃ and continue stirring for 20-30 minutes; d: Add nano-silica-polydopamine composite particles to the above solution, and then sonicate for 15-20 minutes at an ultrasonic power of 400-600W to ensure that the composite particles are uniformly dispersed in the solution. S3: Surface modification reaction: Add the pretreated silica powder to a three-necked flask at a rate of 5-10 g / min while increasing the stirring speed to 600-800 r / min. React at 70-80℃ for 2-3 hours to ensure that the composite modifier is in full contact with the silica powder surface and reacts. During the reaction, reflux is carried out through a condenser to reduce solvent evaporation. S4: Post-processing: After the reaction is complete, filter the reaction product to obtain a solid product. Wash the solid product with deionized water 3-4 times, each time using 2-3 times the mass of the solid product, to remove unreacted modifiers and impurities. Dry the washed solid product in a vacuum drying oven at 60-70℃ for 3-4 hours to obtain the surface-modified silica powder product.