Silica micropowder for organic silicon pouring sealant as well as preparation method and application of silica micropowder

Abstract

The invention provides silica powder for an organic silicon pouring sealant as well as a preparation method and application of the silica powder, and belongs to the technical field of fine organic chemical industry. Ceramic lining ball milling and ceramic grading technologies are utilized to obtain silica micropowder with different finenesses, and a surface treatment technology is combined to modify the silica micropowder; the filling effect of the silica powder in the organic silicon pouring sealant is improved by matching the silica powder with different particle sizes, the elongation at break of the sealant is improved while the thermal conductivity is not reduced and the viscosity is ensured, and the problems of low reinforcing effect and low tensile elongation at break of the traditional silica powder are solved. An alumina ceramic grinding and grading technology is adopted, magnetic substances are not introduced during grinding, an abrasion substance generated during grinding is alumina, the insulativity and thermal conductivity of the abrasion substance are higher than those of silica powder, application of the silica powder in the organic silicon pouring sealant is not affected, and the problem that the magnetic substances of traditional silica powder are too high is solved.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemical industry, and in particular to silicon micropowder for organic silicon potting adhesive, and a preparation method and application thereof. Background Art

[0002] With the development of science and technology and the improvement of people's living standards, electronic devices can be seen everywhere in life, and more and more powerful functions are integrated into small electronic components. Therefore, it is particularly important to provide effective protection for electronic components and implement electronic potting technology with good airtightness, thermal conductivity, flame retardancy and physical protection functions.

[0003] Electronic potting glue mainly includes epoxy potting glue, silicone potting glue and polyurethane potting glue. Among them, silicone potting glue is favored for its excellent high and low temperature resistance, excellent insulation and repairability. However, it also has limitations such as poor adhesion and relatively insufficient thermal conductivity. In order to improve the thermal conductivity of silicone potting glue, materials with good thermal conductivity such as silicon micropowder and aluminum hydroxide are usually used as fillers. Silicon micropowder is also called quartz powder, and its main component is SiO2. It is the most widely used because of its low cost.

[0004] Traditional silicon micropowder is mostly obtained by grinding natural quartz with equipment, and the fineness is mostly 400-1250 mesh. It has a general reinforcing effect on potting glue and poor elongation at break. If silicon micropowder with higher fineness is used, the elongation at break will increase, but it will also increase the viscosity of the system and reduce the thermal conductivity of the system. In addition, since the Mohs hardness of silicon dioxide is 7, the traditional grinding equipment is made of iron, and the equipment wear is high during grinding, resulting in a high content of magnetic substances in the product, which is easy to have an adverse effect on the insulation of the colloid when used. Summary of the invention

[0005] The object of the present invention is to provide a silicon micropowder for silicone potting adhesive and a preparation method and application thereof, wherein the silicon micropowder has a high elongation at break while ensuring viscosity without reducing thermal conductivity, and the product contains less magnetic material.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing silicon micropowder for silicone potting adhesive, comprising the following steps:

[0008] The first silicon-containing raw material is subjected to a first grinding and a first classification in sequence to obtain silicon micropowder of a first fineness;

[0009] The second silicon-containing raw material is subjected to second grinding and second classification in sequence to obtain silicon micropowder of second fineness;

[0010] The first fineness silicon micropowder and the first modifier are mixed to perform a first modification to obtain a first modified silicon micropowder;

[0011] The second fineness silicon micropowder is mixed with a second modifier to perform a second modification to obtain a second modified silicon micropowder;

[0012] Dispersing and mixing the first modified silicon micropowder and the second modified silicon micropowder to obtain silicon micropowder for silicone potting adhesive;

[0013] The average particle size of the first fineness silicon powder is 5.5-6.7 μm, and the average particle size of the second fineness 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 independently ≥ 98%.

[0015] Preferably, the equipment used for the first grinding and the second grinding are independently ceramic-lined ball mills, and the equipment used for the first classification and the second classification are independently ceramic classifiers.

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

[0017] Preferably, the first modifier and the second modifier independently include one or more of KH-550, single-ended trimethoxy silicone oil and stearic acid; the mass of the first modifier is 3 to 12‰ of the mass of the first fineness silicon micropowder, and the mass of the second modifier is 3 to 10‰ of the mass of the second fineness silicon micropowder.

[0018] Preferably, the conditions for the first modification and the second modification independently include: a rotation speed of 1800-2200 r / min, a temperature of 120-140° C., and a time of 10-20 min.

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

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

[0021] The invention provides silicon micropowder for organic silicon potting adhesive prepared by the preparation method.

[0022] The present invention also provides application of the silicon micropowder for organic silicon potting adhesive in the field of electronic potting.

[0023] Beneficial effects of the present invention:

[0024] The present invention solves the problem of voids caused by factors such as particle morphology when filling large particles by using silicon micropowders of different particle sizes. These large particles often produce voids due to irregular shapes or loose arrangements during the filling process, which in turn affects the overall thermal conductivity. The present invention allows small-particle silicon micropowders to be effectively filled into the voids between large-particle silicon micropowders by matching particle sizes. 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 micropowders in silicone potting glue.

[0025] The present invention also combines surface treatment technology to perform surface treatment on silicon micropowder, thereby improving the elongation at break of the colloid without reducing thermal conductivity and ensuring viscosity, thereby solving the problems of low reinforcement effect and low tensile elongation at break of traditional silicon micropowder.

[0026] The present invention adopts alumina ceramic grinding and grading technology, and does not introduce magnetic substances during grinding. The abrasive substance generated during grinding is alumina, which has higher insulation and thermal conductivity than silicon micropowder, does not affect the application of silicon micropowder in silicone potting glue, and solves the problem of high magnetic substance content in traditional silicon micropowder. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing silicon micropowder for silicone potting adhesive, comprising the following steps:

[0028] The first silicon-containing raw material is subjected to a first grinding and a first classification in sequence to obtain silicon micropowder of a first fineness;

[0029] The second silicon-containing raw material is subjected to second grinding and second classification in sequence to obtain silicon micropowder of second fineness;

[0030] The first fineness silicon micropowder and the first modifier are mixed to perform a first modification to obtain a first modified silicon micropowder;

[0031] The second fineness silicon micropowder is mixed with a second modifier to perform a second modification to obtain a second modified silicon micropowder;

[0032] Dispersing and mixing the first modified silicon micropowder and the second modified silicon micropowder to obtain silicon micropowder for silicone potting adhesive;

[0033] The average particle size of the first fineness silicon powder is 5.5-6.7 μm, and the average particle size of the second fineness 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 the silicon-containing raw material to obtain silicon micropowder of first fineness and silicon micropowder of second fineness; specifically: the first silicon-containing raw material is subjected to first grinding and first classification in sequence to obtain silicon micropowder of first fineness, and the second silicon-containing raw material is subjected to second grinding and second classification in sequence to obtain silicon micropowder of second fineness.

[0035] In the present invention, the first silicon-containing raw material and the second silicon-containing raw material are independently preferably prepared from quartz ore which is washed and then fed into a jaw crusher and a rotary cone crusher for crushing. The crushed materials are sieved by a linear vibrating screen to obtain calcite particles with a particle size of 1 to 2 mm, which are 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 independently preferably ≥98%.

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

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

[0038] The present invention preferably preheats the high-speed disperser to a suitable temperature, mixes the first fineness silicon micropowder and the first modifier in the high-speed disperser, performs a first modification, and obtains a first modified silicon micropowder; and mixes the second fineness silicon micropowder and the second modifier in the high-speed disperser, performs a second modification, and obtains a second modified silicon micropowder.

[0039] In the present invention, the first modifier and the second modifier independently preferably include one or more of KH-550, single-ended trimethoxy silicone oil and stearic acid, and further independently preferably include one or more of KH-550 and single-ended trimethoxy silicone oil; wherein KH-550 is used in the form of a KH-550 aqueous solution, and the concentration of the KH-550 aqueous solution is preferably 50%; the present invention has no special limitation on the source of the single-ended trimethoxy silicone oil, and the single-ended trimethoxy silicone oil used in the embodiments of the present invention is a commercially available product with a brand name of CG-MO235.

[0040] In the present invention, when the first modifier and the second modifier are independently KH-550, single-ended trimethoxy silicone oil and stearic acid, the mass ratio of KH-550, single-ended trimethoxy silicone oil and stearic acid is preferably 0-7:0-7:0-7; the order of addition is preferably to first add KH-550 for stirring and then add single-ended trimethoxy silicone oil and stearic acid. KH-550 is added first because KH-550 can react chemically on the surface of silicon micropowder and coat it firmly, thereby improving the compatibility of 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 improving the dispersibility of the powder, which is beneficial to improving the thermal conductivity. The addition of silicone oil and stearic acid is mainly to reduce the oil absorption value, and is also beneficial to improving the compatibility of the powder and the substrate.

[0041] In the present invention, the mass of the first modifier is preferably 3-12‰ of the mass of the first fineness silicon powder, further preferably 3-11‰, and more preferably 3-10‰; the mass of the second modifier is preferably 3-10‰ of the mass of the second fineness silicon powder, further preferably 3-4‰, and more preferably 3‰.

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

[0043] In the present invention, the first modified silicon micropowder and the second modified silicon micropowder are preferably dispersed and mixed, stirred using a high-speed stirrer, and sieved and collected after stirring to obtain silicon micropowder for silicone potting adhesive.

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

[0045] In the present invention, the rotation speed of the dispersion mixing is preferably 70 to 100 r / min, more preferably 80 r / min, and the time is preferably 15 to 30 min, more preferably 20 min.

[0046] The invention provides silicon micropowder for organic silicon potting adhesive prepared by the preparation method.

[0047] The present invention also provides application of the silicon micropowder for organic silicon potting adhesive in the field of electronic potting.

[0048] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope 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 prepared by selecting quartz ore with a silicon dioxide content of more than 98%, washing, successively feeding into a jaw crusher and a rotary cone crusher for crushing, sieving through a linear vibrating screen, obtaining calcite particles with a particle size of 1 to 2 mm, and storing them in a large storage tank for homogenization and storage;

[0051] The first silicon-containing raw material is successively passed into a ceramic-lined ball mill and a ceramic classifier for first grinding and first classification, the first grinding speed is 25 r / min, and the first classification speed is 1800 r / min, to obtain a first fineness silicon powder with an average particle size of 5.5 μm;

[0052] The second silicon-containing raw material is successively passed into a ceramic-lined ball mill and a ceramic classifier for second grinding and second classification, the second grinding speed is 25 r / min, and the second classification speed is 4000 r / min, to obtain a second fineness silicon powder with an average particle size of 1.8 μm;

[0053] The first fineness silicon micropowder is added to a high-speed disperser at a temperature of 120°C, and a KH-550 aqueous solution is added (the KH-550 concentration in the KH-550 aqueous solution is 50%, and the mass of KH-550 is 5‰ of the mass of the first fineness silicon micropowder), the stirring speed is 1800r / min, and the time is 10min, and then the single-end trimethoxy silicone oil with a mass of 3‰ of the mass of the first fineness silicon micropowder and the stearic acid with a mass of 2‰ of the mass of the first fineness silicon micropowder are added, and the stirring is continued for 10min to perform the first modification to obtain the first modified silicon micropowder;

[0054] The second fineness silicon micropowder is added into a high-speed disperser at a temperature of 120°C, and single-ended trimethoxy silicone oil with a mass of 3‰ of the second fineness silicon micropowder is added, and the stirring speed is 1800r / min for 10min to perform a second modification to obtain a second modified silicon micropowder;

[0055] The first modified silicon micropowder and the second modified silicon micropowder were dispersed and mixed in a mass ratio of 12:1, and stirred with a high-speed stirrer at a speed of 80 r / min for 20 min. After stirring, the mixture was sieved, collected, and packaged to obtain the silicon micropowder for silicone potting adhesive 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 prepared by selecting quartz ore with a silicon dioxide content of more than 98%, washing, successively feeding into a jaw crusher and a rotary cone crusher for crushing, sieving through a linear vibrating screen, obtaining calcite particles with a particle size of 1 to 2 mm, and storing them in a large storage tank for homogenization and storage;

[0058] The first silicon-containing raw material is successively passed into a ceramic-lined ball mill and a ceramic classifier for first grinding and first classification, the first grinding speed is 25 r / min, and the first classification speed is 1450 r / min, to obtain a first fineness silicon powder with an average particle size of 6.0 μm;

[0059] The second silicon-containing raw material is successively passed into a ceramic-lined ball mill and a ceramic classifier for second grinding and second classification, the second grinding speed is 25 r / min, and the second classification speed is 3650 r / min, to obtain a second fineness silicon powder with an average particle size of 2.4 μm;

[0060] The first fineness silicon micropowder is added into a high-speed disperser at a temperature of 130°C, and a KH-550 aqueous solution is added (the KH-550 content in the KH-550 aqueous solution is 50%, and the mass of KH-550 is 7‰ of the mass of the first fineness silicon micropowder), and the stirring speed is 1800r / min for 10min, and then stearic acid with a mass of 3‰ of the mass of the first fineness silicon micropowder is added, and stirring is continued for 10min to perform a first modification to obtain a first modified silicon micropowder;

[0061] The second fineness silicon micropowder is added into a high-speed disperser at a temperature of 130°C, and single-ended trimethoxy silicone oil with a mass of 4‰ of the second fineness silicon micropowder is added, and the stirring speed is 2000r / min for 10min to perform a second modification to obtain a second modified silicon micropowder;

[0062] The first modified silicon micropowder and the second modified silicon micropowder were dispersed and mixed in a mass ratio of 13:1, and stirred with a high-speed stirrer at a speed of 80 r / min for 20 min. After stirring, the mixture was sieved, collected, and packaged to obtain the silicon micropowder for silicone potting adhesive 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 prepared by selecting quartz ore with a silicon dioxide content of more than 98%, washing, successively feeding into a jaw crusher and a rotary cone crusher for crushing, sieving through a linear vibrating screen, obtaining calcite particles with a particle size of 1 to 2 mm, and storing them in a large storage tank for homogenization and storage;

[0065] The first silicon-containing raw material is successively passed into a ceramic-lined ball mill and a ceramic classifier for first grinding and first classification, the first grinding speed is 25 r / min, and the first classification speed is 1300 r / min, to obtain a first fineness silicon powder with an average particle size of 6.7 μm;

[0066] The second silicon-containing raw material is successively passed into a ceramic-lined ball mill and a ceramic classifier for second grinding and second classification, the second grinding speed is 25 r / min, and the second classification speed is 3200 r / min, to obtain a second fineness silicon powder with an average particle size of 3.2 μm;

[0067] The first fineness silicon micropowder is added to a high-speed disperser at a temperature of 140°C, and a KH-550 aqueous solution is added (the KH-550 concentration in the KH-550 aqueous solution is 50%, and the mass of KH-550 is 3‰ of the mass of the first fineness silicon micropowder), the stirring speed is 2100r / min, and the time is 10min, and then the single-ended trimethoxy silicone oil with a mass of 1‰ of the mass of the first fineness silicon micropowder and the stearic acid with a mass of 7‰ of the mass of the first fineness silicon micropowder are added, and the stirring is continued for 10min to perform the first modification to obtain the first modified silicon micropowder;

[0068] The second fineness silicon micropowder is added into a high-speed disperser at a temperature of 140°C, and 2‰ of the mass of the second fineness silicon micropowder and 2‰ of the mass of the second fineness silicon micropowder are added, and the stirring speed is 2100r / min for 10min to perform a second modification to obtain a second modified silicon micropowder;

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

[0070] Comparative Example 1

[0071] Commercially available conventional 1250 mesh silica powder was purchased from Lingshou County Baixin New Material Technology Co., Ltd.;

[0072] Comparative Example 2

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

[0074] Application examples and performance measurements

[0075] The silicon powder for silicone potting compound obtained in Examples 1 to 3 and the silicon powder of Comparative Examples 1 to 2 were respectively prepared into silicone potting compounds according to the following formulas, and the properties of the silicone potting compounds were measured according to the following method. The results are shown in Table 1.

[0076] formula:

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

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

[0079] Groups A and B are mixed in a mass ratio of 1:1 to obtain an organic silicone 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 JS11-G1 magnetic substance analyzer from Beijing Hengao Instruments.

[0085] Table 1 Performance test of organic silicon potting glue obtained from silicon micropowder of Examples 1 to 3 and Comparative Examples 1 to 2

[0086]

[0087] By comparing the performance test results of Examples 1 to 3 and Comparative Examples 1 to 2, it can be found that the elongation at break of the silicone potting glue made from the silicon micropowder of the present invention is significantly better than that of conventional commercially available silicon micropowder, the content of magnetic substances is significantly reduced, and the thermal conductivity and viscosity are not much different from those of the silicone potting glue made from conventional silicon micropowder.

[0088] It can be seen from the above embodiments that the present invention provides a silicon micropowder for silicone potting glue, which significantly improves the elongation at break of the silicone potting glue without reducing the thermal conductivity and ensuring the viscosity; at the same time, the magnetic substance in the silicon micropowder for silicone potting glue is reduced, which solves the problems of low reinforcement effect, low tensile elongation at break and high magnetic substance of traditional silicon micropowder.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing silicon micropowder for silicone potting glue, characterized in that: The following steps are involved: The first silicon-containing raw material is subjected to a first grinding and a first classification in sequence to obtain silicon micropowder of a first fineness; The second silicon-containing raw material is subjected to second grinding and second classification in sequence to obtain silicon micropowder of second fineness; The first fineness silicon micropowder and the first modifier are mixed to perform a first modification to obtain a first modified silicon micropowder; The second fineness silicon micropowder is mixed with a second modifier to perform a second modification to obtain a second modified silicon micropowder; Dispersing and mixing the first modified silicon micropowder and the second modified silicon micropowder to obtain silicon micropowder for silicone potting adhesive; The average particle size of the first fineness silicon powder is 5.5-6.7 μm, and the average particle size of the second fineness silicon powder is 1.8-3.2 μm.

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

3. The preparation method according to claim 1, characterized in that: The equipment used for the first grinding and the second grinding is independently a ceramic lined ball mill, and the equipment used for the first classification and the second classification is independently a ceramic classifier.

4. The preparation method according to claim 3, characterized in that: The rotation speeds of the first grinding and the second grinding are independently 15-30 r / min, the rotation speed of the first classification is 1300-1800 r / min, and the rotation speed of the second classification is 3200-4000 r / min.

5. The preparation method according to claim 1, characterized in that: The first modifier and the second modifier independently include one or more of KH-550, single-ended trimethoxy silicone oil and stearic acid; the mass of the first modifier is 3-12‰ of the mass of the first fineness silicon micropowder, and the mass of the second modifier is 3-10‰ of the mass of the second fineness silicon micropowder.

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

7. The preparation method according to claim 1, characterized in that: The mass ratio of the first modified silicon micropowder to the second modified silicon micropowder is 12-14:

1.

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

9. Silicon powder for silicone potting adhesive prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the silicon micropowder for organic silicon potting adhesive according to claim 9 in the field of electronic potting.

Images