CN114804128A

CN114804128A - Spherical silicon dioxide treatment method

Info

Publication number: CN114804128A
Application number: CN202210403342.2A
Authority: CN
Inventors: 张轲轲; 刘金成; 王韶晖; 蒋学鑫
Original assignee: Anhui Estone Material Technology Co ltd
Current assignee: Bengbu Yishitong Electronic Communication Materials Co ltd
Priority date: 2022-04-18
Filing date: 2022-04-18
Publication date: 2022-07-29
Anticipated expiration: 2042-04-18
Also published as: CN114804128B

Abstract

The invention discloses a spherical silicon dioxide treatment method, which relates to the technical field of inorganic powder preparation, wherein dust collecting 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 (4) cleaning and drying the slurry after the hydrothermal reaction to obtain a product. The spherical silicon dioxide treatment method can effectively remove nanoparticles on the surface of the spherical silicon dioxide, reduce the specific surface area of the spherical silicon dioxide, and the obtained spherical silicon dioxide can be widely applied to the fields of EMC packaging, copper clad laminates, silicon rubber and the like.

Description

Spherical silicon dioxide treatment method

The technical field is as follows:

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

Background art:

the spherical silica (spherical quartz powder) is a product obtained by taking irregular-shaped quartz powder as a raw material and performing a spheroidizing process (specifically, the irregular-shaped quartz powder is subjected to melt spheroidization under the action of high temperature and surface tension through a high-temperature flame melting zone). 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 silicon dioxide is subjected to cyclone classification to obtain coarse particles and fine particles (I)Collected by a dust collecting cloth bag, called as dust collecting powder). It was found that the specific surface area of the dust-collecting powder behaves differently compared with conventional spherical silica. For example, D50 has a particle size of 2 to 6 μm and a specific surface area of 6 to 20m ² (normally, coarse particles obtained by cyclone classification, D50 particle size about 5 μm, specific surface area less than 1 m) ² In terms of/g). The reason is that a part of silicon dioxide is vaporized in the spheroidizing process (the temperature of a flame area is 1800-2100 ℃), and the vaporized silicon dioxide forms nano particles in the condensation process and adheres to the surface of fine particle silicon dioxide, so that the specific surface area of the fine particles is increased. Further studies have found that this adhesion is not physisorption, but is analogous to inter-particle "fusion".

The spherical silica with nanoparticles adhered on the surface is not suitable to be added in a polymer in an excessive amount (such as EMC encapsulation, and the viscosity is increased sharply when the specific surface area is too large), so that the application is limited. On the other hand, when wet impurity removal is adopted, the impurities are hard to be formed, an additional process is needed to break up the impurities, and the cost is increased.

The invention content is as follows:

the technical problem to be solved by the invention is to provide a spherical silicon dioxide treatment method, which can remove the 'welded' nano silicon dioxide particles on the surface of the spherical silicon dioxide, obviously reduce the specific surface area of the spherical silicon dioxide, increase the filling amount of the spherical silicon dioxide particles in resin and overcome important technical obstacles for the wide application of the materials.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

a spherical silicon dioxide treatment method comprises the following preparation steps:

(1) adding water into the dust collecting powder to prepare slurry, and adjusting the pH value to be alkaline;

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

(3) and (4) 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 base 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 invention has the beneficial effects that:

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

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

Description of the drawings:

FIG. 1 is an SEM photograph of a dust collected before processing in example 1 of the present invention;

FIG. 2 is an SEM photograph of dust collecting powder after treatment in example 1 of the present invention;

FIG. 3 is an SEM photograph of dust collecting powder after treatment in example 2 of the present invention;

FIG. 4 is an SEM picture of dust collecting powder after treatment in example 3 of the invention;

FIG. 5 is an SEM photograph of the dust collecting powder after treatment in comparative example 1 of the present invention;

FIG. 6 is an SEM photograph of the dust collecting powder after the treatment in comparative example 2 of the present invention.

The specific implementation mode is as follows:

in order to make the technical means, the original characteristics, the achieved purposes and the effects of the invention easy to understand, the invention is further explained by combining the specific embodiments and the drawings.

Example 1

The particle diameter of 21g D50 was 3 μm, and the specific surface area was 9.6m ² Adding 56g of deionized water into per gram of spherical silicon dioxide dust collecting powder, 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 200 ℃, and filtering and cleaning the reacted slurry until the slurry has low conductivityDrying at 5 μ s/cm to obtain loose product with D50 particle size of 2.9 μm and specific surface area of 6.4m ² /g。

Example 2

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

Example 3

Taking 21g of spherical silicon dioxide dust collecting powder same as that in 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 in a 100mL hydrothermal reaction kettle, reacting for 15h at 240 ℃, carrying out suction filtration and cleaning on the reacted slurry until the conductivity of the slurry is less than 5 mu s/cm, drying to obtain a loose product, testing that the D50 particle size is 2.85 mu m, and the specific surface area is 4.6m ² /g。

Comparative example 1

Taking 21g of spherical silicon dioxide dust collecting powder same as that in example 1, adding 56g of deionized water, then adding nitric acid to adjust the pH value to 4, stirring for 30min, placing the obtained slurry in a 100mL hydrothermal reaction kettle, reacting for 15h at 200 ℃, carrying out suction filtration and cleaning on the reacted slurry until the conductivity of the slurry is less than 5 mu s/cm, drying to obtain an agglomerated hard block, wherein the particle size is 2.95 mu m according to a test D50, and the specific surface area is 9.3m ² /g。

Comparative example 2

Taking 21g of spherical silicon dioxide dust collecting powder same as that in example 1, adding 56g of deionized water, then adding ammonia water to adjust the pH value to 9, stirring for 30min, carrying out suction filtration and cleaning on the obtained slurry until the conductivity of the slurry is less than 5 mu s/cm, drying to obtain an agglomerated hard block product, wherein the D50 test shows that the particle size is 3.0 mu m and the specific surface area is 9.6m ² /g。

Fig. 1 and 2 show the dust collecting powder before and after the treatment of example 1, and it can be seen from the figure that the small particles attached to the surface of the spherical silica after the treatment are significantly reduced, and fig. 3 and 4 show that the small particles on the surface of the dust collecting powder after the treatment are further reduced when the PH value is increased or the hydrothermal temperature is increased compared with example 1. Fig. 5 and 6 show the products obtained under the acidic hydrothermal and alkaline non-hydrothermal conditions, respectively, and the small particles attached to the surface of the spherical silica are not obviously reduced.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The method for treating the spherical silicon dioxide is characterized by comprising the following preparation steps:

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

2. The method for treating spherical silica according to claim 1, wherein: the alkali used for adjusting the pH value comprises at least one of sodium hydroxide, potassium hydroxide, ammonia water, ethylenediamine and triethylamine.

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

4. The method for treating spherical silica according to claim 1, wherein: the pH value is adjusted to 9-12.

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

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