Surface modified silica powder and preparation method thereof

Abstract

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

Description

Technical Field

[0001] The invention belongs to the technical field of surface modified silicon micropowder, and specifically refers to surface modified silicon micropowder and a preparation method thereof. Background Art

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

[0003] Traditional silicon micropowder modification methods mostly use a single type of coupling agent. Although it can improve the interface bonding between silicon micropowder and the substrate to a certain extent, it can often only improve one aspect of performance, such as improving dispersibility or enhancing compatibility with a specific type of substrate. In addition, some traditional coupling agents have problems such as high cost and poor environmental protection. With the continuous improvement of modern industry's requirements for material performance, such as the need for good dispersibility, high thermal stability and strong bonding with the substrate in electronic packaging materials, and the need for materials to have good processability and environmental friendliness in environmentally friendly coatings, the development of a new method for preparing surface-modified silicon micropowder with multiple excellent properties and high cost performance has become an urgent problem to be solved. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a novel surface-modified silicon micropowder system and a preparation method thereof which has multiple excellent properties and is cost-effective.

[0005] In order to achieve the above functions, the technical solution adopted by the present invention is as follows: a surface modified silicon micropowder and a preparation method thereof, comprising the following components by weight: silicon micropowder: 88-92 parts, homemade 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.

[0006] Preferably, the average particle size of the silicon powder is 8-20 μm, and the silicon dioxide content thereof is ≥98%.

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

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

[0009] b. Add dopamine monomer to the mixture, the mass ratio of dopamine to nano-silicon dioxide is between 0.5:1-2:1, stir and mix at 200-500 rpm for 12-24 hours to obtain a reactant

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

[0011] Preferably, the dispersant is sodium lignin sulfonate.

[0012] The present invention also discloses a method for preparing surface-modified silicon micropowder, comprising the following steps:

[0013] S1: Pretreatment of silicon micropowder: Place the silicon micropowder in a forced air drying oven and dry it at 100-110°C for 3-4 hours to remove moisture and a small amount of volatile impurities, so that the silicon micropowder is in a dry state, which is conducive to the subsequent modification reaction.

[0014] S2: Preparation of composite modifier solution: Mix and dissolve the starch-based coupling agent, the aluminate coupling agent and the dispersant to prepare a composite modifier solution.

[0015] S3: Surface modification reaction: Add the pretreated silicon micropowder into a three-necked flask, control the silicon micropowder addition speed at 5-10g / min, and increase the stirring speed to 600-800r / min; react at 70-80℃ for 2-3 hours to allow the composite modifier to fully contact and react with the surface of the silicon micropowder.

[0016] During the process, reflux is performed through a condenser to reduce solvent volatilization;

[0017] S4 post-treatment: After the reaction is completed, the reaction product is filtered to obtain a solid product, and the solid product is washed with deionized water for 3-4 times, with the amount of water used each time being 2-3 times the mass of the solid product, so as to remove unreacted modifiers and impurities, and the washed solid product is dried in a vacuum drying oven at 60-70°C for 3-4 hours to obtain a surface-modified silicon micropowder product.

[0018] Preferably, the specific preparation steps of the composite modifier solution in step S2 include:

[0019] a: In a three-necked flask with a stirrer and a thermometer, add homemade starch-based coupling agent, aluminate coupling agent,

[0020] Linking agents and dispersants;

[0021] 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;

[0022] c: Stir at room temperature at a speed of 200-300r / min for 10-15 minutes to make the components preliminarily mixed evenly, then slowly heat to 50-60℃ and continue stirring for 20-30 minutes to make the modifier completely

[0023] Dissolve to form a uniform composite modifier solution;

[0024] Step d: Add the nano-silica-polydopamine composite particles to the above solution, and then perform ultrasonic treatment for 15-20 minutes (ultrasonic power is 400-600W) to uniformly disperse the composite particles in the solution.

[0025] The present invention adopts the above structure to achieve the following beneficial effects: a variety of modifiers can form a bonding or adsorption layer on the surface of silicon micropowder, enhance compatibility with organic matrix, and improve the mechanical properties of materials; dispersants and fine processes ensure that silicon micropowder is well and stably dispersed in the system, avoiding problems such as uneven product performance and coating defects; nano-silicon dioxide-polydopamine composite particles bring special properties such as anti-oxidation and antibacterial, and have application potential in the field of functional materials; homemade starch-based coupling agents and sodium lignin sulfonate are environmentally friendly and low-cost, which are conducive to industrialization and sustainable development; the hydrophilicity and easy agglomeration problems of silicon micropowder are solved, the hydrophobicity and chemical stability are improved, and they are adapted to different application environments. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1:

[0028] A surface modified silicon micropowder comprises the following components by weight: silicon micropowder: 88 parts (average particle size is 8 μm, silicon dioxide content is 98.3%), homemade starch-based coupling agent: 3 parts, aluminate coupling agent: 2 parts, nano silicon dioxide-polydopamine composite particles: 1 part, sodium lignin sulfonate: 1 part.

[0029] The present invention also discloses a method for preparing surface-modified silicon micropowder, comprising the following steps:

[0030] S1: Pretreatment of silicon micropowder: Place the silicon micropowder in a forced air drying oven and dry it at 100°C for 4 hours;

[0031] S2: Preparation of composite modifier solution:

[0032] Step a: In a three-necked flask equipped with a stirrer and a thermometer, add 3 parts of a homemade starch-based coupling agent, 2 parts of an aluminate coupling agent and 1 part of a dispersant;

[0033] Step b: adding 48 parts ((3+2+1)×8) of anhydrous ethanol as a solvent;

[0034] Step c: Stir at room temperature at 200 r / min for 15 minutes, then slowly heat to 50°C and continue stirring for 30 minutes;

[0035] Step d: Add 1 portion of nano-silica-polydopamine composite particles to the above solution and perform ultrasonic treatment at an ultrasonic power of 400 W for 20 minutes.

[0036] S3: Surface modification reaction: The pretreated silicon powder was added into a three-necked flask at a rate of 5 g / min, and the stirring speed was increased to 600 r / min. The mixture was reacted at 70°C for 3 hours and refluxed through a condenser.

[0037] S4: Post-treatment: After the reaction is completed, the solid product is filtered and washed with deionized water, with the amount of water being about 176 parts (about 88 parts by weight of the solid product, 2 times) each time, and washed 4 times. The washed solid product is dried in a vacuum drying oven at 60°C for 4 hours.

[0038] Embodiment 2:

[0039] A surface modified silicon micropowder comprises the following components by weight: silicon micropowder: 90 parts (average particle size 15 μm, silicon dioxide content 98.5%), homemade starch-based coupling agent: 4 parts, aluminate coupling agent: 2.5 parts, nano silicon dioxide-polydopamine composite particles: 1.5 parts, sodium lignin sulfonate: 1.5 parts.

[0040] The present invention also discloses a method for preparing surface-modified silicon micropowder, comprising the following steps:

[0041] S1: Pretreatment of silicon micropowder: Place the silicon micropowder in a forced air drying oven and dry it at 105° C. for 3.5 hours.

[0042] S2: Preparation of composite modifier solution:

[0043] Step a: In a three-necked flask equipped with a stirrer and a thermometer, 4 parts of a homemade starch-based coupling agent, 2.5 parts of an aluminate coupling agent and 1.5 parts of a dispersant were added;

[0044] Step b: adding 72 parts ((4+2.5+1.5)×9) of anhydrous ethanol as solvent;

[0045] Step c: Stir at room temperature at 250 r / min for 12 minutes, then slowly heat to 55°C and continue stirring for 25 minutes;

[0046] Step d: Add 1.5 parts of nano-silica-polydopamine composite particles to the above solution and perform ultrasonic treatment at an ultrasonic power of 500 W for 18 minutes.

[0047] S3: Surface modification reaction: The pretreated silicon powder was added into a three-necked flask at a rate of 8 g / min, and the stirring speed was increased to 700 r / min. The mixture was reacted at 75°C for 2.5 hours and refluxed through a condenser.

[0048] S4: Post-treatment: After the reaction is completed, the solid product is filtered and washed with deionized water, with the amount of water being about 200 parts each time (the mass of the solid product is about 100 parts, 2 times), and washed three times. The washed solid product is dried in a vacuum drying oven at 65°C for 3.5 hours.

[0049] Embodiment 3:

[0050] A surface modified silicon micropowder comprises the following components by weight: silicon micropowder: 92 parts (average particle size 20 μm, silicon dioxide content 98.8%), homemade starch-based coupling agent: 5 parts, aluminate coupling agent: 3 parts, nano silicon dioxide-polydopamine composite particles: 2 parts, sodium lignin sulfonate: 2 parts.

[0051] The present invention also discloses a method for preparing surface-modified silicon micropowder, comprising the following steps:

[0052] S1: Pretreatment of silicon micropowder: Place the silicon micropowder in a forced air drying oven and dry it at 110° C. for 3 hours.

[0053] S2: Preparation of composite modifier solution:

[0054] Step a: In a three-necked flask equipped with a stirrer and a thermometer, 5 parts of a homemade starch-based coupling agent, 3 parts of an aluminate coupling agent and 2 parts of a dispersant were added;

[0055] Step b: adding 90 parts ((5+3+2)×9) of anhydrous ethanol as a solvent;

[0056] Step c: Stir at room temperature at 300 r / min for 10 minutes, then slowly heat to 60°C and continue stirring for 20 minutes;

[0057] Step d: Add 2 portions of nano-silica-polydopamine composite particles to the above solution and perform ultrasonic treatment at an ultrasonic power of 600 W for 15 minutes.

[0058] S3: Surface modification reaction: The pretreated silicon powder was added into a three-necked flask at a speed of 10 g / min, and the stirring speed was increased to 800 r / min. The mixture was reacted at 80°C for 2 hours and refluxed through a condenser.

[0059] S4: Post-treatment: After the reaction is completed, the solid product is filtered and washed with deionized water, with the amount of water being about 276 parts each time (about 138 parts by weight of the solid product, 2 times), washed three times, and the washed solid product was dried in a vacuum drying oven at 70°C for 3 hours.

[0060] Results Data Analysis:

[0061]

[0062] In terms of dispersibility, Example 2 reaches Level 4, which is significantly better than Level 3 of Example 1 and Level 3.5 of Example 3, indicating that it is well dispersed in the medium. This is due to the appropriate component ratio and moderate silicon micropowder particle size, which effectively inhibits the agglomeration phenomenon between particles.

[0063] The contact angle data show that Example 2 (135°) is higher than Example 1 (120°) and Example 3 (130°), indicating that the hydrophobicity is better. Multiple modifiers work synergistically under appropriate conditions to form a better hydrophobic structure on the surface of the silicon micropowder.

[0064] In terms of specific surface area, the 3.2 m 2 / g is higher than 2.5m / g in Example 1 2 / g and 3.0m / g of Example 3 2 / g, a larger specific surface area means more active sites, which is beneficial for interaction with other materials, which is attributed to good dispersion and effective surface modification.

[0065] In terms of bulk density, the 1.1 g / cm 3 Lower than 1.2 g / cm in Example 1 3 and 1.15 g / cm in Example 3 3 , lower bulk density facilitates more uniform distribution in filling applications.

[0066] The standard deviation data of the particle size distribution uniformity show that 0.5 of Example 2 is smaller than 0.8 of Example 1 and 0.6 of Example 3, that is, the particle size distribution uniformity of Example 2 is better and the stability of material performance can be ensured.

[0067] In terms of the content of surface active groups, 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. More active groups provide sufficient sites for reaction or adsorption with other materials.

[0068] In terms of thermal stability, the initial decomposition temperature of Example 2, 400°C, is higher than 350°C of Example 1 and 380°C of Example 3, showing better thermal stability, which is due to the perfect surface modification and good dispersibility.

[0069] In summary, the parameter combination of Example 2 can make the silicon micropowder achieve the best comprehensive performance and better meet the requirements of high-performance surface-modified silicon micropowder.

[0070] The present invention and its implementation methods are described above, and such description is not restrictive. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design structures and embodiments similar to the technical solution without creativity, which should all fall within the protection scope of the present invention.

Claims

1. A surface-modified silicon powder, characterized in that: The composition comprises the following components by weight: 88-92 parts of silicon micropowder, 3-5 parts of homemade 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 dispersant.

2. The surface-modified silicon powder according to claim 1, characterized in that: The preparation method of the nano-silicon dioxide-polydopamine composite particles is as follows: a. The nano-silica colloidal solution is poured into a reaction vessel, tris(hydroxymethylaminomethane) (Tris)-hydrochloric acid buffer solution is added to the nano-silica colloidal solution and mixed, and the volume ratio of the two solutions is 1-2 times so that the PH is between 8-9 to obtain a mixture; b. dopamine monomer is added to the mixture, the mass ratio of dopamine to nano-silica is between 0.5:1-2:1, and the mixture is stirred at 200-500 rpm for 12-24 hours to obtain a reactant; c. The reaction product is centrifuged at a speed of 5000-10000 rpm for 5-10 minutes to remove unreacted dopamine monomers, impurities in the buffer solution, and other by-products that may be formed during the reaction; d. The reaction product is washed with deionized water to further remove residual reactants and impurities, and then dried to obtain nano-silicon dioxide-polydopamine composite particles.

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

4. The surface-modified silicon micropowder according to claim 1, characterized in that: The dispersant is sodium lignin sulfonate.

5. A method for preparing the surface-modified silicon micropowder according to any one of claims 1 to 4, characterized in that: The steps include: S1: Pretreatment of silicon micropowder: Place the silicon micropowder in a blast drying oven and dry it at 100-110°C for 3-4 hours to remove moisture and a small amount of volatile impurities, so that the silicon micropowder is in a dry state, which is conducive to the subsequent modification reaction; S2: Preparation of composite modifier solution: Mixing and dissolving a starch-based coupling agent, an aluminate coupling agent and a dispersant to prepare a composite modifier solution; S3: Surface modification reaction: Add the pretreated silicon micropowder into a three-necked flask, and control the silicon micropowder addition speed to 5-10g / min, while increasing the stirring speed to 600-800r / min; react at 70-80℃ for 2-3 hours to allow the composite modifier to fully contact and react with the surface of the silicon micropowder. During the reaction, reflux through the condenser to reduce solvent volatilization; S4: Post-treatment: After the reaction is completed, the reaction product is filtered to obtain a solid product, and the solid product is washed with deionized water for 3-4 times, with the amount of water used each time being 2-3 times the mass of the solid product, so as to remove unreacted modifiers and impurities, and the washed solid product is dried in a vacuum drying oven at 60-70°C for 3-4 hours to obtain a surface-modified silicon micropowder product.

6. The method for preparing surface-modified silicon micropowder according to claim 5, characterized in that: The specific preparation steps of the composite modifier solution in step S2 include: a: Add homemade starch-based coupling agent, aluminate coupling agent and dispersant into a three-necked flask with a stirrer and a thermometer; 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 room temperature at a speed of 200-300r / min for 10-15 minutes to preliminarily mix the components, then slowly heat to 50-60°C and continue stirring for 20-30 minutes to completely dissolve the modifier to form a uniform composite modifier solution; d: Add nano-silica-polydopamine composite particles to the above solution, and then ultrasonically treat for 15-20 minutes (ultrasonic power is 400-600W) to uniformly disperse the composite particles in the solution.

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