CN114804128B

CN114804128B - Spherical silicon dioxide treatment method

Info

Publication number: CN114804128B
Application number: CN202210403342.2A
Authority: CN
Inventors: 张轲轲; 刘金成; 王韶晖; 蒋学鑫
Original assignee: Bengbu Yishitong Electronic Communication Materials Co ltd
Current assignee: Bengbu Yishitong Electronic Communication Materials Co ltd
Priority date: 2022-04-18
Filing date: 2022-04-18
Publication date: 2023-08-29
Anticipated expiration: 2042-04-18
Also published as: CN114804128A

Abstract

The invention discloses a spherical silicon dioxide treatment method, which relates to the technical field of inorganic powder preparation, wherein dust collection powder is prepared into slurry by adding water, and the pH value is adjusted to be alkaline; adding the slurry into a reaction kettle for hydrothermal reaction; and (3) cleaning and drying the slurry after the hydrothermal reaction to obtain a product. The spherical silicon dioxide treatment method can effectively remove nano particles on the surface of the spherical silicon dioxide, reduce the specific surface area of the spherical silicon dioxide, and can be widely applied to the fields of EMC packaging, copper-clad plates, silicon rubber and the like.

Description

Spherical silicon dioxide treatment method

Technical field:

the invention relates to the technical field of inorganic powder preparation, in particular to a spherical silicon dioxide treatment method.

The background technology is as follows:

spherical silica (spherical quartz powder) is a product obtained by taking irregular-morphology quartz powder as a raw material and performing a spheroidization process (specifically, the irregular-morphology quartz powder passes through a high-temperature flame melting zone and is melted and spheroidized under the action of high temperature and surface tension). The spherical silicon dioxide has the characteristics of low dielectric constant, low expansion coefficient, high filling rate and the like, and is widely applied to the fields of EMC packaging, copper-clad plates, silicon rubber and the like.

The spherical silica is subjected to cyclone classification to obtain coarse particles and fine particles (generally collected by a dust collection cloth bag, and called dust collection powder). It was found that the specific surface area of the dust collecting powder was different from that of the conventional spherical silica. For example, the D50 particle size is 2 to 6 μm, the specific surface area is 6 to 20m ² Per g (normally, coarse particles obtained by cyclone classification, D50 particle size of about 5 μm, specific surface area of less than 1m ² /g). The reason is that a part of the silica is vaporized during the spheroidization (flame zone temperature 1800-2100 deg.c), and the vaporized silica forms nano particles during the condensation, adhering to the surface of the fine particle silica, resulting in an increase in the specific surface area of the fine particle. Further studies have found that this adhesion is not physical adsorption, but rather resembles inter-particle "fusion".

Such spherical silica with nanoparticles adhered to the surface is limited in use because the specific surface area is too large, and the addition amount in the polymer is not too large (such as EMC potting, which causes a sharp increase in viscosity. On the other hand, when wet impurity removal is adopted, hard blocks are formed, and extra working procedures are needed for scattering, so that the cost is increased.

The invention comprises the following steps:

the invention aims to solve the technical problem of providing a spherical silicon dioxide treatment method, which can remove nano silicon dioxide particles welded on the surface of spherical silicon dioxide, obviously reduce the specific surface area of the nano silicon dioxide particles, increase the filling amount of the nano silicon dioxide particles in resin, and overcome important technical barriers for the wide application of the material.

The technical problems to be solved by the invention are realized by adopting the following technical scheme:

a method for treating spherical silica, comprising the following preparation steps:

(1) Adding water into dust collection powder to prepare slurry, and regulating the pH value to be alkaline;

(2) Adding the slurry into a reaction kettle for hydrothermal reaction;

(3) And (3) cleaning and drying the slurry after the hydrothermal reaction to obtain a product.

The alkali used for adjusting the pH value comprises at least one of sodium hydroxide, potassium hydroxide, ammonia water, ethylenediamine and triethylamine.

In order to reduce metal ions in the product, the alkali used for adjusting the pH value is preferably ammonia water, ethylenediamine or triethylamine.

The pH value is adjusted to 9-12.

The hydrothermal reaction temperature is 150-240 ℃.

The hydrothermal reaction time is 4-20 h.

The beneficial effects of the invention are as follows:

1. the spherical silicon dioxide treatment method has the characteristics of simple operation, high efficiency and feasibility, and is suitable for industrial production.

2. The spherical silicon dioxide treatment method can effectively remove nano particles on the surface of the spherical silicon dioxide, reduce the specific surface area of the spherical silicon dioxide, and can be widely applied to the fields of EMC packaging, copper-clad plates, silicon rubber and the like.

Description of the drawings:

FIG. 1 is an SEM image of dust collection powder before treatment of example 1;

FIG. 2 is an SEM image of the dust of the invention after treatment of example 1;

FIG. 3 is an SEM image of the dust of the invention after treatment of example 2;

FIG. 4 is an SEM image of the dust of the invention after treatment of example 3;

FIG. 5 is an SEM image of the dust of the invention after treatment of comparative example 1;

FIG. 6 is an SEM image of the dust of comparative example 2 after the treatment of the present invention.

The specific embodiment is as follows:

the invention is further described below with reference to specific embodiments and illustrations in order to make the technical means, the creation features, the achievement of the purpose and the effect of the implementation of the invention easy to understand.

Example 1

21g of D50 particles with a particle size of 3 μm and a specific surface area of 9.6m were taken ² Adding 56g of deionized water into per g of spherical silicon dioxide dust collection powder, adding ammonia water to adjust the pH value to 9, stirring for 30min, placing the obtained slurry into a 100mL hydrothermal reaction kettle, reacting for 15h at 200 ℃, pumping and filtering the reacted slurry until the conductivity of the slurry is less than 5 mu s/cm, drying to obtain a loose product, and testing the D50 particle size to be 2.9 mu m and the specific surface area to be 6.4m ² /g。

Example 2

Taking 21g of spherical silicon dioxide dust collecting powder which is the same as that of example 1, adding 56g of deionized water, adding triethylamine to adjust the pH value to 12, stirring for 30min, placing the obtained slurry into a 100mL hydrothermal reaction kettle, reacting for 15h at 200 ℃, pumping, filtering and washing the reacted slurry until the conductivity of the slurry is less than 5 mu s/cm, drying to obtain a loose product, and testing the particle size of D50 to be 2.8 mu m and the specific surface area to be 3.4m ² /g。

Example 3

Taking 21g of spherical silicon dioxide dust collecting powder which is the same as that of example 1, adding 56g of deionized water, then adding ammonia water to adjust the pH value to 9, stirring for 30min, placing the obtained slurry into a 100mL hydrothermal reaction kettle, reacting for 15h at 240 ℃,washing the reacted slurry with suction to obtain slurry with conductivity less than 5 μs/cm, stoving to obtain loose product with D50 particle size of 2.85 microns and specific surface area of 4.6m ² /g。

Comparative example 1

Taking 21g of spherical silicon dioxide dust collecting powder which is the same as that of example 1, adding 56g of deionized water, adding nitric acid to adjust the pH value to 4, stirring for 30min, placing the obtained slurry into a 100mL hydrothermal reaction kettle, reacting for 15h at 200 ℃, pumping, filtering and washing the reacted slurry until the conductivity of the slurry is less than 5 mu s/cm, drying to obtain agglomerated hard lumps, and testing that the D50 particle size is 2.95 mu m and the specific surface area is 9.3m ² /g。

Comparative example 2

Taking 21g of spherical silicon dioxide dust collecting powder which is the same as that of example 1, adding 56g of deionized water, adding ammonia water to adjust the pH value to 9, stirring for 30min, filtering and washing the obtained slurry until the conductivity of the slurry is less than 5 mu s/cm, drying to obtain an agglomerated hard lump product, and testing the particle size of D50 to be 3.0 mu m and the specific surface area to be 9.6m ² /g。

Fig. 1 and 2 show dust collecting powders before and after treatment in example 1, and it can be seen from the figures that the small particles adhering to the surface of spherical silica after treatment are significantly reduced, and fig. 3 and 4 show dust collecting powders after treatment, wherein the surface small particles are further reduced when the PH value is increased or the hydrothermal temperature is increased, as compared with example 1. Fig. 5 and 6 show the products obtained under acidic hydrothermal and alkaline non-hydrothermal conditions, respectively, without significantly reducing the adhesion of small particles on the surface of the spherical silica.

The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A method for treating spherical silica, comprising the steps of:

(2) Adding the slurry into a reaction kettle for hydrothermal reaction;

(3) Washing and drying the slurry after the hydrothermal reaction to obtain a product;

the pH value is adjusted to 9-12;

the alkali used for regulating the pH value comprises at least one of sodium hydroxide, potassium hydroxide, ammonia water, ethylenediamine and triethylamine;

the dust collecting powder has a D50 particle diameter of 3 mu m and a specific surface area of 9.6m ² Spherical silica/g; the surface of the spherical silica is welded with nano silica particles.

2. The method for treating spherical silica according to claim 1, wherein: the alkali used for regulating the pH value is ammonia water, ethylenediamine or triethylamine.

3. The method for treating spherical silica according to claim 1, wherein: the hydrothermal reaction temperature is 150-240 ℃.

4. The method for treating spherical silica according to claim 1, wherein: the hydrothermal reaction time is 4-20 h.