Silicon micropowder for silicone pouring sealant, and preparation method and application thereof

Abstract

The application provides a silicon powder for organic silicon pouring sealant and a preparation method and application thereof, and belongs to the technical field of fine organic chemical industry. The silicon powder with different fineness is obtained by using ceramic lining ball milling and ceramic grading technology, and the silicon powder is modified by combining with surface treatment technology; the filling effect of the silicon powder in the organic silicon pouring sealant is improved by using silicon powders with different particle sizes, the elongation at break of the glue is improved without reducing the thermal conductivity and ensuring the viscosity, and the problems of low reinforcing effect and low elongation at break of traditional silicon powder are solved. In the application, the alumina ceramic grinding and grading technology is adopted, no magnetic material is introduced during grinding, and the abrasion material generated during grinding is alumina, which has higher insulation and thermal conductivity than the silicon powder, does not affect the application of the silicon powder in the organic silicon pouring sealant, and solves the problem of high magnetic material of traditional silicon powder.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and in particular to a silica micropowder for organosilicon potting compound, its preparation method and application. Background Technology

[0002] With the development of science and technology and the improvement of people's living standards, electronic devices are ubiquitous in our lives, and more and more powerful functions are being integrated into tiny electronic components. Therefore, providing effective protection for electronic components and implementing electronic potting technology with good sealing properties, thermal conductivity, flame retardant properties, and physical protection functions is particularly important.

[0003] Electronic potting compounds are mainly classified into three categories: epoxy potting compounds, silicone potting compounds, and polyurethane potting compounds. Among them, silicone potting compounds are favored due to their excellent high and low temperature resistance, outstanding insulation, and repairability. However, they also have limitations such as poor adhesion and relatively insufficient thermal conductivity. To improve the thermal conductivity of silicone potting compounds, materials with good thermal conductivity, such as silica powder and aluminum hydroxide, are usually used as fillers. Silica powder, also known as quartz powder, is mainly composed of SiO2 and is the most widely used due to its low cost.

[0004] Traditional silica powder is mostly obtained by grinding natural quartz using equipment, with a fineness of 400-1250 mesh. Its reinforcing effect on potting compounds is generally poor, and its elongation at break is low. Using finer silica powder increases the elongation at break, but also increases the system viscosity and decreases the system's thermal conductivity. Furthermore, since silica has a Mohs hardness of 7, and traditional grinding equipment is made of iron, the equipment wears out quickly during grinding, resulting in a higher concentration of magnetic materials in the product. This can negatively impact the insulating properties of the colloid during application. Summary of the Invention

[0005] The purpose of this invention is to provide a silica micro powder for silicone potting compound, its preparation method and application. The silica micro powder has high elongation at break without reducing thermal conductivity and ensuring viscosity, and the product contains low magnetic material content.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing silica micropowder for silicone potting compounds, comprising the following steps:

[0008] The first silicon-containing raw material is subjected to first grinding and first classification in sequence to obtain silicon micro powder of first fineness.

[0009] The second silicon-containing raw material is subjected to a second grinding and a second classification in sequence to obtain silicon micro powder of a second fineness.

[0010] The first fine silicon powder and the first modifier are mixed and subjected to the first modification to obtain the first modified silicon powder;

[0011] The second fine silicon powder and the second modifier are mixed to carry out the second modification, thereby obtaining the second modified silicon powder;

[0012] The first modified silicon powder and the second modified silicon powder are dispersed and mixed to obtain silicon powder for organosilicon potting compound;

[0013] The average particle size of the first fine silicon powder is 5.5–6.7 μm, and the average particle size of the second fine silicon powder is 1.8–3.2 μm.

[0014] Preferably, the silicon dioxide content in the first silicon-containing raw material and the second silicon-containing raw material is ≥98% independently.

[0015] Preferably, the equipment used for the first grinding and the second grinding is a ceramic-lined ball mill, and the equipment used for the first grading and the second grading is a ceramic classifier.

[0016] Preferably, the rotation speed of the first grinding and the second grinding is 15-30 r / min, the rotation speed of the first grading is 1300-1800 r / min, and the rotation speed of the second grading is 3200-4000 r / min.

[0017] Preferably, the first modifier and the second modifier independently include one or more of KH-550, single-terminated trimethoxysilane oil and stearic acid; the mass of the first modifier is 3 to 12‰ of the mass of the first fine silica powder, and the mass of the second modifier is 3 to 10‰ of the mass of the second fine silica powder.

[0018] Preferably, the conditions for the first modification and the second modification are independent, including: a rotation speed of 1800-2200 r / min, a temperature of 120-140℃, and a time of 10-20 min.

[0019] Preferably, the mass ratio of the first modified silicon micro powder to the second modified silicon micro powder is 12 to 14:1.

[0020] Preferably, the dispersion and mixing temperature is 120–140°C, the rotation speed is 80–100 r / min, and the time is 15–20 min.

[0021] This invention provides silica micropowder for organosilicon potting compounds prepared by the above-described preparation method.

[0022] This invention also provides the application of the aforementioned silicone potting compound's silicon micropowder in the field of electronic potting.

[0023] The beneficial effects of this invention are:

[0024] This invention solves the void problem caused by particle morphology and other factors when using a combination of silicon microparticles with different particle sizes. These large particles often create voids during the filling process due to their irregular shape or loose arrangement, thus affecting the overall thermal conductivity. This invention, through particle size matching, allows small silicon microparticles to effectively fill the voids between large silicon microparticles. This not only reduces the presence of voids but also significantly reduces the adverse effects on thermal conductivity, thereby improving the filling effect of silicon microparticles in silicone potting compounds.

[0025] This invention also incorporates surface treatment technology to treat the silicon micropowder, thereby improving the elongation at break of the colloid without reducing thermal conductivity and ensuring viscosity, thus solving the problems of low reinforcing effect and low tensile elongation at break of traditional silicon micropowder.

[0026] This invention employs alumina ceramic grinding and grading technology, which does not introduce magnetic materials during grinding. The wear material generated during grinding is alumina, which has higher insulation and thermal conductivity than silicon micropowder. This does not affect the application of silicon micropowder in organosilicon potting compounds and solves the problem of excessive magnetic material content in traditional silicon micropowder. Detailed Implementation

[0027] This invention provides a method for preparing silica micropowder for silicone potting compounds, comprising the following steps:

[0028] The first silicon-containing raw material is subjected to first grinding and first classification in sequence to obtain silicon micro powder of first fineness.

[0029] The second silicon-containing raw material is subjected to a second grinding and a second classification in sequence to obtain silicon micro powder of a second fineness.

[0030] The first fine silicon powder and the first modifier are mixed and subjected to the first modification to obtain the first modified silicon powder;

[0031] The second fine silicon powder and the second modifier are mixed to carry out the second modification, thereby obtaining the second modified silicon powder;

[0032] The first modified silicon powder and the second modified silicon powder are dispersed and mixed to obtain silicon powder for organosilicon potting compound;

[0033] The average particle size of the first fine silicon powder is 5.5–6.7 μm, and the average particle size of the second fine silicon powder is 1.8–3.2 μm.

[0034] The present invention preferably utilizes two ceramic-lined ball mills and two ceramic classifiers to grind and classify silicon-containing raw materials to obtain first-fineness silicon micro powder and second-fineness silicon micro powder; specifically: the first silicon-containing raw material is subjected to first grinding and first classification in sequence to obtain first-fineness silicon micro powder, and the second silicon-containing raw material is subjected to second grinding and second classification in sequence to obtain second-fineness silicon micro powder.

[0035] In this invention, the first silicon-containing raw material and the second silicon-containing raw material are preferably obtained by washing quartz ore and feeding it into a jaw crusher and a rotary cone crusher for crushing. The crushed material is then screened by a linear vibrating screen to obtain calcite particles with a particle size of 1-2 mm, which are then stored in a large storage tank for homogenization. The first silicon-containing raw material and the second silicon-containing raw material are the same, and the silicon dioxide content in the first silicon-containing raw material and the second silicon-containing raw material is preferably ≥98%.

[0036] In this invention, the rotation speed of the first grinding and the second grinding is preferably 15-30 r / min, more preferably 25 r / min; the rotation speed of the first grading is preferably 1300-1800 r / min, more preferably 1450-1800 r / min; and the rotation speed of the second grading is preferably 3200-4000 r / min, more preferably 3200-3650 r / min.

[0037] In this invention, the average particle size of the first fine silicon powder is preferably 5.5 to 6.7 μm, more preferably 5.5 to 6.0 μm, and even more preferably 5.5 μm; the average particle size of the second fine silicon powder is preferably 1.8 to 3.2 μm, more preferably 1.8 to 2.4 μm, and even more preferably 1.8 μm.

[0038] In this invention, the high-speed disperser is preheated to a suitable temperature, and the first fine silicon powder and the first modifier are mixed in the high-speed disperser to perform the first modification, thereby obtaining the first modified silicon powder; the second fine silicon powder and the second modifier are mixed in the high-speed disperser to perform the second modification, thereby obtaining the second modified silicon powder.

[0039] In this invention, the first modifier and the second modifier preferably include one or more of KH-550, single-terminated trimethoxysilicone oil, and stearic acid, and more preferably one or more of KH-550 and single-terminated trimethoxysilicone oil; wherein KH-550 is used in the form of KH-550 aqueous solution, and the concentration of KH-550 aqueous solution is preferably 50%; this invention does not have a special limitation on the source of the single-terminated trimethoxysilicone oil, and the single-terminated trimethoxysilicone oil used in the embodiments of this invention is a commercially available product with the brand name CG-MO235.

[0040] In this invention, when the first modifier and the second modifier are independently KH-550, single-terminated trimethoxysilane oil, and stearic acid, the preferred mass ratio of KH-550, single-terminated trimethoxysilane oil, and stearic acid is 0-7:0-7:0-7. The preferred order of addition is to add KH-550 first and stir, then add the single-terminated trimethoxysilane oil and stearic acid. KH-550 is added first because it can undergo a chemical reaction on the surface of silicon micropowder, forming a strong coating, thereby improving the compatibility between silicon dioxide and the substrate. As a modifier, the addition of KH-550 can improve the strength and elongation at break of silicon micropowder, while also improving the dispersibility of the powder, which is beneficial to improving thermal conductivity. The addition of silicone oil and stearic acid is mainly to reduce the oil absorption value, and also to improve the compatibility between the powder and the substrate.

[0041] In this invention, the mass of the first modifier is preferably 3 to 12‰ of the mass of the first fine silicon micro powder, more preferably 3 to 11‰, and even more preferably 3 to 10‰; the mass of the second modifier is preferably 3 to 10‰ of the mass of the second fine silicon micro powder, more preferably 3 to 4‰, and even more preferably 3‰.

[0042] In this invention, the conditions for the first modification and the second modification are preferably independently as follows: the rotation speed is preferably 1800-2000 r / min, more preferably 1800-1900 r / min, and even more preferably 1800 r / min; the temperature is preferably 120-140°C, more preferably 120-130°C, and even more preferably 120°C; and the time is preferably 10-20 min, more preferably 15-20 min, and even more preferably 20 min.

[0043] The present invention preferably involves dispersing and mixing the first modified silicon micro powder and the second modified silicon micro powder, stirring with a high-speed mixer, and then sieving and collecting the mixture after stirring to obtain silicon micro powder for organosilicon potting compound.

[0044] In this invention, the mass ratio of the first modified silicon micro powder to the second modified silicon micro powder is preferably 12 to 14:1, and more preferably 13:1.

[0045] In this invention, the preferred rotation speed for dispersion mixing is 70-100 r / min, more preferably 80 r / min, and the preferred time is 15-30 min, more preferably 20 min.

[0046] This invention provides silica micropowder for organosilicon potting compounds prepared by the above-described preparation method.

[0047] This invention also provides the application of the aforementioned silicone potting compound's silicon micropowder in the field of electronic potting.

[0048] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1

[0050] In this embodiment, the first silicon-containing raw material and the second silicon-containing raw material are independently obtained by selecting quartz ore with a silicon dioxide content of more than 98%, washing them, and feeding them into a jaw crusher and a rotary cone crusher for crushing. After being screened by a linear vibrating screen, calcite particles with a particle size of 1-2 mm are obtained and stored in a large storage tank for homogenization.

[0051] The first silicon-containing raw material was successively fed into a ball mill with a ceramic liner and a ceramic classifier for first grinding and first classification. The rotation speed of the first grinding was 25 r / min and the rotation speed of the first classification was 1800 r / min, to obtain first fine silicon powder with an average particle size of 5.5 μm.

[0052] The second silicon-containing raw material was successively fed into a ball mill with a ceramic liner and a ceramic classifier for second grinding and second classification. The rotation speed of the second grinding was 25 r / min and the rotation speed of the second classification was 4000 r / min, to obtain second fine silicon micro powder with an average particle size of 1.8 μm.

[0053] The first fine silica powder was added to a high-speed disperser at 120°C, and a KH-550 aqueous solution (the KH-550 concentration in the KH-550 aqueous solution was 50%, and the mass of KH-550 was 5‰ of the mass of the first fine silica powder) was added. The stirring speed was 1800 r / min for 10 min. Then, a single-terminated trimethoxy silicone oil with a mass of 3‰ of the mass of the first fine silica powder and stearic acid with a mass of 2‰ of the mass of the first fine silica powder were added. The stirring was continued for 10 min to carry out the first modification and obtain the first modified silica powder.

[0054] The second fineness silica powder was added to a high-speed disperser at 120°C, and 3‰ of the second fineness silica powder by weight of single-terminated trimethoxy silicone oil was added. The stirring speed was 1800 r / min and the time was 10 min to carry out the second modification and obtain the second modified silica powder.

[0055] The first modified silicon powder and the second modified silicon powder were dispersed and mixed at a mass ratio of 12:1. The mixture was stirred using a high-speed mixer at a speed of 80 r / min for 20 min. After stirring, the mixture was sieved, collected, and packaged to obtain the silicone potting compound silicon powder of Example 1.

[0056] Example 2

[0057] In this embodiment, the first silicon-containing raw material and the second silicon-containing raw material are independently obtained by selecting quartz ore with a silicon dioxide content of more than 98%, washing them, and feeding them into a jaw crusher and a rotary cone crusher for crushing. After being screened by a linear vibrating screen, calcite particles with a particle size of 1-2 mm are obtained and stored in a large storage tank for homogenization.

[0058] The first silicon-containing raw material was successively fed into a ball mill with a ceramic liner and a ceramic classifier for first grinding and first classification. The rotation speed of the first grinding was 25 r / min and the rotation speed of the first classification was 1450 r / min, to obtain first fine silicon micro powder with an average particle size of 6.0 μm.

[0059] The second silicon-containing raw material was successively fed into a ball mill with a ceramic liner and a ceramic classifier for second grinding and second classification. The rotation speed of the second grinding was 25 r / min and the rotation speed of the second classification was 3650 r / min, to obtain second fine silicon powder with an average particle size of 2.4 μm.

[0060] The first fine silica powder was added to a high-speed disperser at 130°C, and a KH-550 aqueous solution (the KH-550 content in the KH-550 aqueous solution was 50%, and the mass of KH-550 was 7‰ of the mass of the first fine silica powder) was added. The stirring speed was 1800 r / min for 10 min. Then, stearic acid with a mass of 3‰ of the mass of the first fine silica powder was added, and the stirring was continued for 10 min to carry out the first modification, thereby obtaining the first modified silica powder.

[0061] The second fineness silica powder was added to a high-speed disperser at a temperature of 130°C, and 4‰ of the second fineness silica powder by weight of single-terminated trimethoxy silicone oil was added. The stirring speed was 2000 r / min and the time was 10 min to carry out the second modification and obtain the second modified silica powder.

[0062] The first modified silicon powder and the second modified silicon powder were dispersed and mixed at a mass ratio of 13:1. The mixture was stirred using a high-speed mixer at a speed of 80 r / min for 20 min. After stirring, the mixture was sieved, collected, and packaged to obtain the silicon powder for organosilicon potting compound of Example 2.

[0063] Example 3

[0064] In this embodiment, the first silicon-containing raw material and the second silicon-containing raw material are independently obtained by selecting quartz ore with a silicon dioxide content of more than 98%, washing them, and feeding them into a jaw crusher and a rotary cone crusher for crushing. After being screened by a linear vibrating screen, calcite particles with a particle size of 1-2 mm are obtained and stored in a large storage tank for homogenization.

[0065] The first silicon-containing raw material was successively fed into a ball mill with a ceramic liner and a ceramic classifier for first grinding and first classification. The rotation speed of the first grinding was 25 r / min and the rotation speed of the first classification was 1300 r / min, resulting in first fine silicon powder with an average particle size of 6.7 μm.

[0066] The second silicon-containing raw material was successively fed into a ball mill with a ceramic liner and a ceramic classifier for second grinding and second classification. The rotation speed of the second grinding was 25 r / min and the rotation speed of the second classification was 3200 r / min, to obtain second fine silicon micro powder with an average particle size of 3.2 μm.

[0067] The first fine silica powder was added to a high-speed disperser at 140°C, and a KH-550 aqueous solution (KH-550 concentration in the KH-550 aqueous solution was 50%, and the mass of KH-550 was 3‰ of the mass of the first fine silica powder) was added. The stirring speed was 2100 r / min for 10 min. Then, a single-terminated trimethoxy silicone oil with a mass of 1‰ of the mass of the first fine silica powder and stearic acid with a mass of 7‰ of the mass of the first fine silica powder were added. The mixture was stirred for another 10 min to carry out the first modification and obtain the first modified silica powder.

[0068] The second fine silica powder was added to a high-speed disperser at a temperature of 140°C, along with 2‰ of the mass of the second fine silica powder, a single-terminated trimethoxy silicone oil, and 2‰ of the mass of the second fine silica powder, and stearic acid. The stirring speed was 2100 r / min for 10 min to carry out the second modification, thereby obtaining the second modified silica powder.

[0069] The first modified silicon powder and the second modified silicon powder were dispersed and mixed at a mass ratio of 14:1. The mixture was stirred using a high-speed mixer at a speed of 80 r / min for 20 min. After stirring, the mixture was sieved, collected, and packaged to obtain the silicone potting compound silicon powder of Example 3.

[0070] Comparative Example 1

[0071] Commercially available standard 1250 mesh silicon micro powder was purchased from Lingshou County Baixin New Material Technology Co., Ltd.

[0072] Comparative Example 2

[0073] Commercially available 5000-mesh silicon powder was purchased from Lianyungang Miaojing Silicon Materials Co., Ltd.

[0074] Application examples and performance testing

[0075] The silicone potting compounds obtained in Examples 1-3 and the silicone powders in Comparative Examples 1-2 were prepared according to the following formulations to obtain silicone potting compounds. The properties of the silicone potting compounds were measured according to the following methods, and the results are shown in Table 1.

[0076] formula:

[0077] Group A: 250g methyl vinyl polysiloxane, 42.5g hydrogen-containing silicone oil (Shin-Etsu silicone oil, KF99, Japan), 525g silica powder, 1.25g cyclohexanol;

[0078] Group B: 250g methyl vinyl polysiloxane, 525g silica powder, 0.5g Karstedt catalyst;

[0079] Groups A and B are mixed at a mass ratio of 1:1 to obtain an organosilicon potting compound.

[0080] method:

[0081] Viscosity (mPa.s): HG / T 5053-2016;

[0082] Elongation at break (%): GB / T 528-2009;

[0083] Thermal conductivity (W·m) -1· k -1 ): ASTM D5470;

[0084] Magnetic substances (ppm): Measured using the JS11-G1 magnetic material analyzer from Beijing Hengaode Instruments.

[0085] Table 1 Performance tests of the organosilicon potting compounds obtained from silicon micropowder in Examples 1-3 and Comparative Examples 1-2

[0086]

[0087] Comparing the performance test results of Examples 1-3 and Comparative Examples 1-2, it can be found that the elongation at break of the organosilicon potting compound prepared from the silicon micropowder of the present invention is significantly better than that of conventional commercially available silicon micropowder, the content of magnetic materials is significantly reduced, and the thermal conductivity and viscosity are not much different from those of the organosilicon potting compound prepared from conventional silicon micropowder.

[0088] As can be seen from the above embodiments, the present invention provides a silicon micro powder for silicone potting compounds. The silicon micro powder for silicone potting compounds significantly improves the elongation at break of silicone potting compounds without reducing thermal conductivity and ensuring viscosity. At the same time, the amount of magnetic material in the silicon micro powder for silicone potting compounds is reduced, which solves the problems of low reinforcing effect, low elongation at break, and high magnetic material content of traditional silicon micro powders.

[0089] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing silica micropowder for organosilicon potting compounds, characterized in that, Includes the following steps: The first silicon-containing raw material is subjected to first grinding and first classification in sequence to obtain silicon micro powder of first fineness. The second silicon-containing raw material is subjected to a second grinding and a second classification in sequence to obtain silicon micro powder of a second fineness. The first fine silicon powder and the first modifier are mixed and subjected to the first modification to obtain the first modified silicon powder; The second fine silicon powder and the second modifier are mixed to carry out the second modification, thereby obtaining the second modified silicon powder; The first modified silicon powder and the second modified silicon powder are dispersed and mixed to obtain silicon powder for organosilicon potting compound; the mass ratio of the first modified silicon powder and the second modified silicon powder is 12-14:

1. The equipment used for the first grinding and the second grinding is a ceramic-lined ball mill, and the equipment used for the first grading and the second grading is a ceramic classifier. The average particle size of the first fine silicon powder is 5.5–6.7 μm, and the average particle size of the second fine silicon powder is 1.8–3.2 μm. The first modifier and the second modifier independently include one or more of KH-550, single-terminated trimethoxysilane oil, and stearic acid; The rotation speeds of the first and second grinding processes are independently 15–30 r / min, the rotation speed of the first stage is 1300–1800 r / min, and the rotation speed of the second stage is 3200–4000 r / min. The mass of the first modifier is 3 to 12‰ of the mass of the first fine silicon powder, and the mass of the second modifier is 3 to 10‰ of the mass of the second fine silicon powder.

2. The preparation method according to claim 1, characterized in that, The silicon dioxide content in both the first and second silicon-containing raw materials is ≥98%.

3. The preparation method according to claim 1, characterized in that, The conditions for the first and second modifications are independent and include: a rotation speed of 1800–2200 r / min, a temperature of 120–140 °C, and a time of 10–20 min.

4. The preparation method according to claim 1, characterized in that, The dispersion and mixing temperature is 120–140°C, the rotation speed is 80–100 r / min, and the time is 15–20 min.

5. Silicone micropowder for organosilicon potting compound prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the silicone micropowder for the silicone potting compound according to claim 5 in the field of electronic potting.

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