A method for preparing gaseous modified spherical silica powder

Abstract

The present invention is a method for preparing gaseous modified spherical silicon dioxide powder, which selects spherical silicon dioxide micropowder as raw material, adopts a gaseous modification method to purify and activate the spherical silicon dioxide powder first, and then performs gaseous modification treatment of a silane coupling agent, and provides different gaseous heat treatment environments through two-stage reactors, thereby ensuring sufficient contact between the treatment agent and the surface of the spherical silicon dioxide. The present invention can realize continuous production of silicon dioxide powder modification pretreatment and modification treatment process on the one hand, and continuous and uninterrupted production in a workshop on the other hand, and can obtain modified spherical silicon dioxide micropowder with low conductivity, uniform coating of the modifier, and excellent compatibility with resin through the impurity removal of the primary reaction and the three-dimensional dynamic reaction process of the gaseous modifier.

Description

Technical Field

[0001] The invention relates to a modification method of non-metallic powder, in particular to a preparation method of gaseous modified spherical silicon dioxide powder, belonging to the technical field of silicon material processing. Background Art

[0002] Spherical silica has become the preferred filler in the mid-to-high-end semiconductor industry due to its large specific surface area, excellent fluidity, and low thermal expansion coefficient. With the advancement of technology and the advent of high-precision, multifunctional products, the requirements for spherical silica fillers are also increasing, especially in the field of electronic device packaging, which requires it to have lower electrical conductivity and higher thermal conductivity. This requires surface treatment of spherical silica to improve the dispersion of particles in composite materials, the wettability between interfaces, and increase the filling amount of fillers, thereby improving the comprehensive performance of composite materials and meeting downstream application needs.

[0003] At present, the surface modification methods of spherical silica mainly include physical coating modification, alcohol and lipid modification, polymer grafting, coupling agent modification and in-situ modification, etc. The modification methods adopted can be divided into wet modification and dry modification. Wet modification is to dissolve dry nano-silica and modifiers in organic solvents such as benzene, toluene, and n-hexane for heating reaction, and then separate and dry to obtain modified silica. The post-processing process of its products is complicated, and the organic solvent pollution is large, which is not suitable for industrial development. Dry modification is a modification process in which dry nano-silica is contacted with an organic modifier and reacts, which is easy to cause a lot of dust and cannot achieve continuous operation.

[0004] Chinese patent document CN101517012A uses an acidic dispersion containing ethanol, water, etc. as a solvent and adopts a coupling agent to wet-modify silicon dioxide. It requires more solvent and takes a long time to react.

[0005] Chinese patent document CN113604073A adopts dry stirring modification of coupling agent at different temperature gradients, adds silane coupling agent to silicon dioxide powder, and conducts high temperature and high pressure stirring reaction under sealed conditions, which is time-consuming and cannot achieve continuous modification operation. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a continuous method for preparing gaseous modified spherical silicon dioxide powder in view of the deficiencies in the prior art, which can effectively reduce the electrical conductivity of the product.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solution: The present invention is a method for preparing gaseous modified spherical silicon dioxide powder, which is characterized by the following steps:

[0008] (1) Raw materials: Spherical silica powder is selected as the raw material. The median particle size of the raw material is 100nm~10μm, the fluidity is not more than 600s / 50g, and the hydrogen ion content in the room temperature water extract is 1.00×10 -3 ~1.00×10 -5.5 mol / L;

[0009] (2) Preheating: Preheating by introducing a hot air flow of 150°C to 500°C into the first-stage negative pressure gas modification reactor until the temperature inside the first-stage negative pressure gas modification reactor is between 150°C and 500°C, and the negative pressure is controlled at -0.1MPa to -0.5MPa;

[0010] (3) Primary gas treatment: Spherical silica powder is continuously fed into the preheated primary negative pressure gas modification reactor using a feeding device, and the activator is simultaneously introduced into the gasification carrier in the primary negative pressure gas modification reactor through an activator delivery pipeline, and a hot air flow of 150°C to 500°C is continuously introduced to maintain the temperature in the primary negative pressure gas modification reactor at 150°C to 500°C, and the negative pressure is maintained at -0.1MPa to -0.5MPa; the spherical silica powder is circulated and turned over by the hot air flow in the primary negative pressure reactor, collides with each other, and the powder surface is activated and pretreated under a high temperature heat treatment environment; the activator is selected from one or more of deionized water, ammonia water or hydrogen peroxide; the mass ratio of spherical silica to activator is 1 to 100:1;

[0011] (4) Secondary gaseous modification treatment: The spherical silica powder after primary treatment is mixed and homogenized in the middle and lower layers of the reactor due to gravity, and is sucked into the secondary reactor through negative pressure airflow. The temperature in the secondary reactor is controlled at 150°C~500°C, and the negative pressure is maintained at -0.1MPa~-0.5MPa; a surface treatment modifier is introduced into the gasification carrier in the secondary reactor through a pipeline, and the surface treatment modifier is selected from silane coupling agents containing vinyl, isocyanate, acyl, phenyl, alkyl, epoxy, amino, mercapto or alkoxy groups; the mass ratio of spherical silica to surface treatment modifier is 10~1000:1; the modified powder is sucked into the silo port through negative pressure, and the modified product is collected by an oscillator.

[0012] The method for preparing gaseous modified spherical silicon dioxide powder described in the present invention has a further preferred technical solution: two-stage negative pressure gaseous modification reactors are interconnected, a blower is arranged outside the first-stage negative pressure gaseous modification reactor, and an induced draft fan is arranged outside the second-stage negative pressure gaseous modification reactor, and the negative pressure environment of the overall environment is maintained by controlling the power of the blower and induced draft fan. The airflow is transported to the first-stage negative pressure gaseous modification reactor by the blower and enters the second-stage reactor after circulating and flipping in the reactor. After circulating and flipping again, the airflow is brought out by the induced draft fan, so that a stable negative pressure passage is maintained in the entire system.

[0013] The method for preparing gaseous modified spherical silicon dioxide powder of the present invention has a further preferred technical solution that the introduced activating agent is sprayed out through a plurality of gasification nozzles installed in a primary negative pressure gaseous modification reactor, and the nozzle pressure is 0.1 MPa to 0.4 MPa.

[0014] The method for preparing gaseous modified spherical silicon dioxide powder described in the present invention has a further preferred technical solution: the feeding device is selected from one of a screw feeder, a belt feeder, a roller feeder, an impeller feeder, a disc feeder or a vibrating feeder, and the feeding volume or mass per unit time is controlled by the speed or power of the feeder.

[0015] The method for preparing gaseous modified spherical silicon dioxide powder of the present invention has a further preferred technical solution: during preheating, the temperature of the preheated hot air flow is 180°C~300°C, the temperature in the first-level negative pressure gas modification reactor is preheated to 180°C~300°C, and the negative pressure is controlled at -0.2MPa~-0.3MPa.

[0016] The method for preparing gaseous modified spherical silicon dioxide powder of the present invention has a further preferred technical solution: during the primary gas treatment process, the hot air flow introduced into the primary negative pressure gas modification reactor is 180°C~300°C, the temperature in the primary negative pressure gas modification reactor is maintained at 180°C~300°C, and the negative pressure is maintained at -0.2MPa~-0.3MPa.

[0017] The method for preparing gaseous modified spherical silicon dioxide powder of the present invention has a further preferred technical solution that in the primary gaseous treatment process, the mass ratio of spherical silicon dioxide to activator is 5-50:1.

[0018] The method for preparing gaseous modified spherical silicon dioxide powder of the present invention has a further preferred technical solution: in the secondary gaseous modification treatment, the temperature in the secondary reactor is controlled at 180°C to 300°C, and the negative pressure is maintained at -0.2MPa to -0.3MPa.

[0019] The method for preparing gaseous modified spherical silicon dioxide powder of the present invention has a further preferred technical solution that in the secondary gaseous modification treatment, the mass ratio of spherical silicon dioxide to the surface treatment modifier is 40-100:1.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention adopts a gaseous modification method to first purify and activate the spherical silicon oxide powder, and then performs a gaseous modification treatment of the silane coupling agent. A gaseous heat treatment environment is provided by two-stage reactors to ensure sufficient contact between the treatment agent and the surface of the spherical silicon dioxide, thereby realizing continuous and uninterrupted modification production of the production line.

[0022] 2. The present invention can realize continuous production of silica powder modification pretreatment and modification process on the one hand, and can realize continuous and uninterrupted production in the workshop on the other hand. Through the impurity removal of the primary reaction and the three-dimensional dynamic reaction process of the gaseous modifier, modified spherical silica powder with low conductivity, uniform modifier coating and excellent compatibility with resin can be obtained.

[0023] 3. The activator is in a high-temperature gasified state in the reactor. Within a certain range of addition, it can fully contact the surface of spherical silica without producing a wetting and bonding effect. While activating the hydroxyl groups on the surface of the powder, the soluble impurities on the surface of the spherical silica are desorbed due to the contact and collision of the activator and are taken away under the guidance of the hot air flow. The gaseous pretreatment plays a role in impurity removal, purification and surface activation. On the one hand, it can reduce the content of soluble impurities on the surface of the powder in the pretreatment stage to obtain spherical powder with low conductivity. On the other hand, it can improve the surface activity of the powder, which is convenient for the next step of surface modification.

[0024] 4. On the one hand, the continuous and uninterrupted two-stage treatment reduces the number of steps in the modification process and realizes assembly line production. On the other hand, it can keep the activated powder in a high-temperature active state without the influence of the intermediate treatment process, and directly enter the modification process, which promotes the complete reaction of the modification process, thereby improving the compatibility between the modified powder and the resin and reducing the resin viscosity. DETAILED DESCRIPTION

[0025] The specific implementation modes of the present invention are further described below in detail to facilitate further understanding of the present invention by those skilled in the art, but it does not constitute a limitation on the rights thereof.

[0026] Embodiment 1:

[0027] Spherical silica powder with a D50 of 5 μm is fed into a first-stage negative pressure reactor through a screw feeder, the hot air flow temperature is set at 250°C, the system negative pressure is controlled at -0.24 MPa by adjusting the induced draft fan and the blower power, and deionized water is sprayed into the gasification nozzle 1 for activation pretreatment, the nozzle pressure is set to 0.15 MPa, and the mass ratio of the amount of spherical silica to the amount of deionized water is adjusted to 20:1. The silane coupling agent KH560 is sprayed into the gasification nozzle 2 for modification treatment, the nozzle pressure is set to 0.2 MPa, the hot air flow temperature is set to 250°C, and the mass ratio of the amount of spherical silica to the amount of silane coupling agent KH560 is adjusted to 80:1 to obtain a modified spherical silica product.

[0028] Embodiment 2:

[0029] Spherical silica powder with a D50 of 2 μm is fed into a first-stage negative pressure reactor through a screw feeder, the hot air flow temperature is set at 180°C, the system negative pressure is controlled at -0.3 MPa by adjusting the induced draft fan and the blower power, and deionized water is sprayed into the gasification nozzle 1 for activation pretreatment, the nozzle pressure is set to 0.21 MPa, and the mass ratio of the amount of spherical silica to the amount of deionized water is adjusted to 25:1. The gasification nozzle 2 is sprayed with silane coupling agent A171 for modification treatment, the nozzle pressure is set to 0.23 MPa, and the mass ratio of the amount of spherical silica to the amount of silane coupling agent A171 is adjusted to 80:1 to obtain a modified spherical silica product.

[0030] Embodiment 3:

[0031] Spherical silica powder with a D50 of 0.5 μm is fed into a first-stage negative pressure reactor through a screw feeder, the hot air flow temperature is set at 230°C, the system negative pressure is controlled at -0.3 MPa by adjusting the induced draft fan and the blower power, and deionized water is sprayed into the gasification nozzle 1 for activation pretreatment, the nozzle pressure is set to 0.2 MPa, and the mass ratio of the amount of spherical silica to the amount of deionized water added is adjusted to 20:1. The silane coupling agent KH550 is sprayed into the gasification nozzle 2 for modification treatment, the nozzle pressure is set to 0.2 MPa, and the mass ratio of the amount of spherical silica to the amount of silane coupling agent KH550 added is adjusted to 50:1 to obtain a modified spherical silica product.

[0032] Embodiment 4:

[0033] Spherical silica powder with a D50 of 0.5 μm is fed into a first-stage negative pressure reactor through a screw feeder, the hot air flow temperature is set at 195°C, the system negative pressure is controlled at -0.32 MPa by adjusting the induced draft fan and the blower power, and deionized water is sprayed into the gasification nozzle 1 for activation pretreatment, the nozzle pressure is set to 0.18 MPa, and the mass ratio of the amount of spherical silica to the amount of deionized water added is adjusted to 50:1. The gasification nozzle 2 is sprayed with silane coupling agent KBM13 for modification treatment, the nozzle pressure is set to 0.2 MPa, and the mass ratio of the amount of spherical silica to the amount of silane coupling agent KBM13 added is adjusted to 50:1 to obtain a modified spherical silica product.

[0034] Embodiment 5:

[0035] Spherical silica powder with a D50 of 0.5 μm is fed into a first-stage negative pressure reactor through a screw feeder, the hot air flow temperature is set at 180°C, the system negative pressure is controlled at -0.25 MPa by adjusting the induced draft fan and the blower power, and deionized water is sprayed into the gasification nozzle 1 for activation pretreatment, the nozzle pressure is set to 0.22 MPa, and the mass ratio of the amount of spherical silica to the amount of deionized water is adjusted to 20:1. Silane coupling agent A171 is sprayed into the gasification nozzle 2 for modification treatment, the nozzle pressure is set to 0.24 MPa, and the mass ratio of the amount of spherical silica to the amount of silane coupling agent A171 is adjusted to 100:1 to obtain a modified spherical silica product.

[0036] Comparative Example 1

[0037] Spherical silica powder with a D50 of 0.5 μm was directly added to a mixer, and dry-modified with silane coupling agent KH550. The mass ratio of the added amount of spherical silica to the added amount of silane coupling agent KH550 was adjusted to 100:1 to obtain a modified spherical silica product.

[0038] Comparative Example 2

[0039] Spherical silica powder with a D50 of 2 μm was directly added to a mixer, and dry-modified with a silane coupling agent KH550. The mass ratio of the added amount of spherical silica to the silane coupling agent KH560 was adjusted to 200:1 to obtain a modified spherical silica product.

[0040] The products obtained from the above examples and comparative examples were evaluated using the following methods:

[0041] a. Conductivity measurement

[0042] An aqueous dispersion of silica fine powder was prepared (10.0 g of silica / 100 mL of pure water, 25° C.), and the conductivity was measured using an alternating current two-electrode conductivity meter.

[0043] b. Determination of viscosity of resin mixture

[0044] The modified silica powder and the basic bisphenol F epoxy resin were ultrasonically mixed and degassed at a mass ratio of 5:3, and the viscosity was tested using a rotational viscometer in a water bath at 23±2°C.

[0045] c. Liquidity test

[0046] Use a Hall flow meter to test the fluidity of spherical powders, and record the time required for 50 grams of sample to flow completely through the Hall flow meter funnel. Repeat three times and take the arithmetic mean; if the powder does not flow when the small hole is opened, tap the funnel lightly to make the powder start to flow.

[0047] The results are as follows:

[0048]

Claims

1. A method for preparing gaseous modified spherical silicon dioxide powder, characterized in that: The steps are as follows: (1) Raw materials: Spherical silica powder is selected as the raw material. The median particle size of the raw material is 100nm~10μm, the fluidity is not more than 600s / 50g, and the hydrogen ion content in the room temperature water extract is 1.00×10 -3 ~1.00×10 -5.5 mol / L; (2) Preheating: Preheating by introducing a hot air flow of 150°C to 500°C into the first-stage negative pressure gas modification reactor until the temperature inside the first-stage negative pressure gas modification reactor is between 150°C and 500°C, and the negative pressure is controlled at -0.1MPa to -0.5MPa; (3) Primary gas treatment: Spherical silica powder is continuously fed into the preheated primary negative pressure gas modification reactor using a feeding device, and the activator is simultaneously introduced into the gasification carrier in the primary negative pressure gas modification reactor through an activator delivery pipeline, and a hot air flow of 150°C to 500°C is continuously introduced to maintain the temperature in the primary negative pressure gas modification reactor at 150°C to 500°C, and the negative pressure is maintained at -0.1MPa to -0.5MPa; the spherical silica powder is circulated and turned over by the hot air flow in the primary negative pressure reactor, collides with each other, and the powder surface is activated and pretreated under a high temperature heat treatment environment; the activator is selected from one or more of deionized water, ammonia water or hydrogen peroxide; the mass ratio of spherical silica to activator is 1 to 100:1; (4) Secondary gaseous modification treatment: The spherical silica powder after primary treatment is mixed and homogenized in the middle and lower layers of the reactor due to gravity, and is sucked into the secondary reactor through negative pressure airflow. The temperature in the secondary reactor is controlled at 150°C~500°C, and the negative pressure is maintained at -0.1MPa~-0.5MPa; a surface treatment modifier is introduced into the gasification carrier in the secondary reactor through a pipeline, and the surface treatment modifier is selected from silane coupling agents containing vinyl, isocyanate, acyl, phenyl, alkyl, epoxy, amino, mercapto or alkoxy groups; the mass ratio of spherical silica to surface treatment modifier is 10~1000:1; the modified powder is sucked into the silo port through negative pressure, and the modified product is collected by an oscillator.

2. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: The two-stage negative pressure gas modification reactors are interconnected. A blower is arranged outside the first-stage negative pressure gas modification reactor and an induced draft fan is arranged outside the second-stage negative pressure gas modification reactor. The power of the blower and induced draft fan is controlled to maintain the negative pressure environment of the overall environment. The airflow is transported to the first-stage negative pressure gas modification reactor by the blower and enters the second-stage reactor after circulating and flipping in the reactor. After circulating and flipping again, the airflow is brought out by the induced draft fan, so that a stable negative pressure passage is maintained in the whole system.

3. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: The introduced activating agent is sprayed out through a plurality of gasification nozzles installed in a first-stage negative pressure gas modification reactor, and the nozzle pressure is 0.1MPa to 0.4MPa.

4. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: The feeding device is selected from one of a screw feeder, a belt feeder, a roller feeder, an impeller feeder, a disc feeder or a vibrating feeder, and the feeding volume or mass per unit time is controlled by the speed or power of the feeder.

5. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: During preheating, the temperature of the preheated hot air flow is 180°C~300°C, and the temperature in the first-level negative pressure gas modification reactor is preheated to 180°C~300°C, and the negative pressure is controlled at -0.2MPa~-0.3MPa.

6. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: During the primary gas treatment process, the hot air flow introduced into the primary negative pressure gas modification reactor is 180°C ~ 300°C, the temperature in the primary negative pressure gas modification reactor is maintained at 180°C ~ 300°C, and the negative pressure is maintained at -0.2MPa ~ -0.3MPa.

7. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: In the primary gas treatment process, the mass ratio of spherical silica to activator is 5~50:

1.

8. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: In the secondary gaseous modification treatment, the temperature in the secondary reactor is controlled at 180°C ~ 300°C, and the negative pressure is maintained at -0.2MPa ~ -0.3MPa.

9. The method for preparing gaseous modified spherical silicon dioxide powder according to claim 1, characterized in that: In the secondary gaseous modification treatment, the mass ratio of spherical silica to surface treatment modifier is 40~100:1.

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