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CN-121991357-A - Modified polydimethylsiloxane and organic silicon pouring sealant and preparation method thereof

CN121991357ACN 121991357 ACN121991357 ACN 121991357ACN-121991357-A

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to modified polydimethylsiloxane and organosilicon pouring sealant and a preparation method thereof. The modified polydimethylsiloxane prepared by the invention is modified vinyl-terminated polydimethylsiloxane, and is used as one of raw materials for preparing the organic silicon pouring sealant, the organic silicon pouring sealant comprises a component A and a component B, and the organic silicon pouring sealant is defined to comprise, by weight, 100 parts of modified vinyl-terminated polydimethylsiloxane, 1400-1600 parts of heat conducting powder, 1-15 parts of silane coupling agent, 0.5-5 parts of platinum catalyst, 0.5-5 parts of cross-linking agent and 0.1-0.5 part of inhibitor. The modified polydimethylsiloxane provided by the invention can improve the compatibility of the heat conducting powder, so that the organosilicon pouring sealant has high heat conductivity coefficient and low viscosity.

Inventors

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Assignees

  • 科建高分子材料（上海）股份有限公司

Dates

Publication Date
20260508
Application Date
20260226

Claims (10)

  1. 1. A modified polydimethylsiloxane is characterized by comprising a modified polymerized unit with a structure shown in a formula (I) and a basic polymerized unit with a structure shown in a formula (II): Formula (I): ; formula (II): ; Wherein x1 and x2 are each 25 to 55; The mass ratio of the formula (I) to the formula (II) is 1:3-5; The dynamic viscosity of the modified polydimethylsiloxane is 15-55 cP.
  2. 2. The method for preparing the modified polydimethylsiloxane as recited in claim 1, comprising the steps of: Mixing vinyl-terminated polydimethylsiloxane with a structure shown in a formula (III), trimethoxy silicon-based-terminated polydimethylsiloxane with a structure shown in a formula (IV) and a catalyst for heating reaction to obtain the modified polydimethylsiloxane; Formula (III): ; Formula (IV): ; wherein n1 is 25 to 55, and n2 is 2 to 10.
  3. 3. The organic silicon pouring sealant comprises a component A and a component B, wherein the component A comprises, by weight, 50 parts of modified vinyl-terminated polydimethylsiloxane, 700-800 parts of heat conducting powder, 0.5-7.5 parts of long-chain silane coupling agent and 0.5-5 parts of platinum catalyst; the component B comprises, by weight, 50 parts of modified vinyl-terminated polydimethylsiloxane, 700-800 parts of heat conducting powder, 0.5-7.5 parts of long-chain silane coupling agent, 0.5-5 parts of cross-linking agent and 0.1-0.5 parts of reversible catalytic activity inhibitor; the modified vinyl-terminated polydimethylsiloxane is the modified polydimethylsiloxane of claim 1 or the modified polydimethylsiloxane prepared by the preparation method of claim 2.
  4. 4. The silicone potting adhesive of claim 3 wherein the cross-linking agent comprises a pendant hydrogen-containing and methyl-terminated polydimethylsiloxane having the formula Wherein m1 is 5-50, m2 is 5-50, m1 and m2 are integers, and the dynamic viscosity of the crosslinking agent is 20-50 cP.
  5. 5. The organic silicon pouring sealant according to claim 3, wherein the heat conducting powder adopted by the component A and the heat conducting powder adopted by the component B are the same, the heat conducting powder comprises large-particle heat conducting powder, medium-particle heat conducting powder and small-particle heat conducting powder, the average particle size of the large-particle heat conducting powder is 70-100 microns, the average particle size of the medium-particle heat conducting powder is 25-65 microns, the average particle size of the small-particle heat conducting powder is 2-10 microns, the mass ratio of the large-particle heat conducting powder, the medium-particle heat conducting powder and the small-particle heat conducting powder is (6-8): (2-4): (1-2), and the heat conducting powder comprises one or more of aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride and boron nitride.
  6. 6. The silicone potting adhesive of claim 3, wherein the long chain silane coupling agent comprises one or more of dodecyl trimethoxysilane, dodecyl triethoxysilane, hexadecyl trimethoxysilane, hexadecyl triethoxysilane, octadecyl trimethoxysilane, and octadecyl triethoxysilane.
  7. 7. The organic silicon pouring sealant according to claim 3, wherein the platinum catalyst is a vinyl silicone oil platinum complex, and the platinum atom content of the platinum catalyst is 2000-50000 ppm; The reversible catalytic activity inhibitor is tetravinyl tetramethyl cyclotetrasiloxane, 3, 5-dimethyl-1-hexynol, methyl ethyl alkynol or 1-ethynyl cyclohexanol.
  8. 8. The preparation method of the organic silicon pouring sealant according to any one of claims 3 to 7, comprising the following steps: Mixing modified vinyl-terminated polydimethylsiloxane, heat conducting powder and long-chain silane coupling agent, and performing heating reaction to obtain a mixed base material; mixing part of the mixed base material with a platinum catalyst to obtain a component A; and mixing the rest mixed base material, the cross-linking agent and the reversible catalytic activity inhibitor to obtain a component B.
  9. 9. The application of the organic silicon pouring sealant prepared by the preparation method of any one of claims 3-7 or 8 as a pouring sealant in filling electronic components.
  10. 10. A method for encapsulating electronic components by adopting organosilicon pouring sealant comprises the following steps: Mixing the component A and the component B of the organic silicon pouring sealant according to any one of claims 3-7, and performing vacuum defoaming to obtain organic silicon pouring sealant slurry; and encapsulating the organosilicon potting adhesive slurry in an electronic component for curing.

Description

Modified polydimethylsiloxane and organic silicon pouring sealant and preparation method thereof Technical Field The invention belongs to the technical field of high polymer materials, and particularly relates to modified polydimethylsiloxane and organosilicon pouring sealant and a preparation method thereof. Background With the rapid development of new energy, power electronics, photovoltaic energy storage and other strategic emerging industries, electronic and electrical equipment is iteratively upgraded towards integration, miniaturization and high power. In core components such as an on-board charger (OBC), a power Battery Management System (BMS), a photovoltaic inverter, a high-power LED driving module and the like, the heat generated in the running process of equipment is increased sharply due to the great improvement of power density, and the fact that local temperature is too high becomes a key bottleneck for limiting the reliability, service life and upper performance limit of the equipment. Therefore, the encapsulating material with the high-efficiency heat-conducting performance and the reliable protection function becomes one of core supporting materials for guaranteeing the stable operation of the electronic equipment. The pouring sealant is used as a key material for packaging electronic equipment, and has the core functions of heat conduction, insulation protection, moisture prevention, dust prevention, vibration impact resistance and the like by filling gaps between components and parts and wrapping sensitive components. The organic silicon pouring sealant is widely applied in the field of electronic packaging by virtue of excellent high and low temperature resistance (the temperature range of-60 ℃ to 200 ℃ or even wider) of the organic silicon pouring sealant, good electrical insulation, low modulus elasticity and ageing resistance. However, the conventional silicone potting adhesive mainly aims at insulation and heat insulation, and has low heat conductivity coefficient (usually 0.8-2W/(m)K) And between) can only meet the basic heat dissipation requirement of middle-low power equipment, and cannot adapt to the high-efficiency heat management requirement in a high-power and high-heat-generation scene. In order to solve the heat dissipation problem of high heating equipment, research, development and application of high-heat-conductivity organic silicon pouring sealant have been developed in the industry. In the prior art, the main mode for improving the heat conduction performance of the organic silicon pouring sealant is to add a heat conduction filler into an organic silicon matrix, and the common heat conduction filler comprises aluminum oxide, aluminum nitride, boron nitride, silicon carbide and the like. However, the existing high heat conduction products have a plurality of technical points that part of the products are required to have high heat conduction coefficient (for example, the heat conduction coefficient reaches 3W/(m)K) Above), the filling amount of the heat conducting filler needs to be greatly increased, so that the viscosity of the pouring sealant is obviously increased, the fluidity is reduced, tiny gaps are difficult to fully fill, and the packaging effect of the precise component with a complex structure is poor. In addition, the compatibility of the heat conducting filler in the organic silicon pouring sealant is poor, and the heat conducting coefficient cannot be effectively improved. The related art discloses a low-viscosity heat-conducting pouring sealant, which has a heat conductivity coefficient lower than 3W/(m)K) . Another related art discloses a low-viscosity heat-conducting pouring sealant, which adopts an anti-settling agent such as white carbon black and the like to prevent powder from settling, but the anti-settling agent increases the thixotropy of the sizing material to a certain extent, is unfavorable for self-leveling of the pouring sealant, and has lower heat conductivity coefficient. In summary, adding a large amount of heat conducting powder in the prior art results in poor compatibility, and further results in that the organosilicon pouring sealant does not have the performance of low viscosity and high heat conductivity. Disclosure of Invention The invention aims to provide a modified polydimethylsiloxane and organosilicon pouring sealant and a preparation method thereof, the modified polydimethylsiloxane provided by the invention can improve the compatibility of the heat conducting powder, so that the organosilicon pouring sealant has high heat conductivity coefficient and low viscosity. In order to achieve the purpose of the invention, the invention provides the following technical scheme: A modified polydimethylsiloxane is characterized by comprising a modified polymerized unit with a structure shown in a formula (I) and a basic polymerized unit with a structure shown in a formula (II): Formula (I): ; formula (II): ; Wherein x1 and x2 are each