CN-122011772-A - Silica gel composite material with high heat conductivity and low dielectric property and preparation method thereof

CN122011772ACN 122011772 ACN122011772 ACN 122011772ACN-122011772-A

Abstract

The invention provides a high-heat-conductivity and low-dielectric silica gel composite material and a preparation method thereof, comprising the following steps of S1, adding a two-dimensional filler into an acid ester aqueous solvent, regulating the pH value to a preset range, carrying out hydrolysis condensation reaction to enable the surface of the two-dimensional filler to deposit and form a transition layer to obtain a primary product, S2, modifying the transition layer of the primary product to form a pore structure, adding a one-dimensional filler in the modification process to enable the one-dimensional filler to be in the pore structure of the transition layer to obtain a built-in material, S3, adding a three-dimensional filler into the built-in material, stirring and mixing the three-dimensional filler to obtain a composite filler, uniformly mixing the composite filler with a silica gel matrix, curing and forming to obtain the high-heat-conductivity and low-dielectric silica gel composite material, and realizing structural connection of fillers with different dimensions through the transition layer to form a mutually-penetrating heat-conducting network, and realizing high heat-conductivity under lower filler consumption, and simultaneously reducing the whole density of the material and considering the low dielectric property of the material.

Inventors

ZHAO HUA
SHAO SUJUN
YIN MINGMING

Assignees

深圳市景图材料科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260311

Claims (8)

1. The preparation method of the silica gel composite material with high heat conductivity and low dielectric property is characterized by comprising the following steps: S1, adding a two-dimensional filler into an acid ester aqueous solvent, regulating the pH value to a preset range, and performing hydrolytic condensation reaction to deposit the surface of the two-dimensional filler to form a transition layer, so as to obtain a primary product; S2, modifying the transition layer of the primary product to form a pore structure, and adding one-dimensional filler in the modification process to enable the one-dimensional filler to be in the pore structure of the transition layer, so as to obtain a built-in material; And S3, adding the three-dimensional filler into the embedded material, stirring and mixing to obtain a composite filler, uniformly mixing the composite filler with the silica gel matrix, and curing and forming to obtain the silica gel composite material with high heat conductivity and low dielectric property.
2. The method for preparing a silica gel composite material with high thermal conductivity and low dielectric constant according to claim 1, wherein step S1 comprises: S1.1, adding a two-dimensional filler into a solvent containing a precursor, performing ultrasonic dispersion, adding a regulator to adjust the pH value until the pH value reaches a preset pH value, and performing hydrolytic condensation reaction on the precursor to form precursor sediment on the surface of the two-dimensional filler; s1.2, adding a pore-forming agent to enable the precursor sediment to form a pore structure, and converting the precursor sediment into a transition layer to obtain a primary product.
3. The method for preparing the silica gel composite material with high heat conductivity and low dielectric property according to claim 2, wherein the mass ratio of the two-dimensional filler to the solvent is 1:6-30, the two-dimensional filler comprises one of boron nitride, molybdenum disulfide and carbon nitride, the solvent comprises water and organic matters, the organic matters comprise one of ethanol, isopropanol, methanol and n-butanol, the regulator is selected from at least one of ammonia water, sodium hydroxide and triethylamine, the precursor comprises at least one of silicate, titanate and aluminate precursors, the dosage of the precursor is 1-10% of the mass of the two-dimensional filler, the pore-forming agent comprises at least one of polyethylene glycol, ammonium bicarbonate, urea and sodium dodecyl sulfate, the dosage of the pore-forming agent is 0.5-5% of the mass of the two-dimensional filler, the power of ultrasonic dispersion is 200-500W, and the dispersion time is 10-30min.
4. The method for preparing a silica gel composite material with high thermal conductivity and low dielectric constant according to claim 1, wherein step S2 comprises: S2.1, heating and ultrasonic combined treatment are carried out on the primary product, one-dimensional filler is added, high-speed shearing is carried out, and uniform mixing is carried out, so that a pore structure is formed on the transition layer; s2.2, performing hydrolytic condensation reaction to solidify the pore structure of the transition layer, and embedding the one-dimensional filler in the pores of the transition layer to obtain the embedded material.
5. The method for preparing the silica gel composite material with high heat conductivity and low dielectric property according to claim 4, wherein the heating temperature of the heating ultrasonic combined treatment is 40-60 ℃, the ultrasonic power is 300-600W, the treatment time is 5-20min, the rotating speed of the high-speed shearing mixing is 800-1500r/min, the mixing time is 5-15min, the heat preservation temperature of the continuous hydrolytic condensation is 50-70 ℃, the heat preservation time is 1-3h, the one-dimensional filler comprises at least one of boron nitrogen nanotubes and alumina nanofibers, and the dosage of the one-dimensional filler is 1-5% of the mass of the two-dimensional filler.
6. The method for preparing the silica gel composite material with high heat conductivity and low dielectric property according to claim 1, wherein the step S3 comprises the steps of S3.1, adding the three-dimensional filler into the built-in material, then performing ultrasonic dispersion, stirring and mixing, wherein the ultrasonic power is 200-400W, the dispersion time is 5-10min, the stirring rotation speed is 300-800r/min, and the mixing time is 10-30min, so that the three-dimensional filler is uniformly filled in a gap between the transition layer and the two-dimensional filler, and is in close contact with the outer surface of the transition layer, thereby obtaining the composite filler; S3.2, uniformly mixing the composite filler and the silica gel matrix by low-temperature shearing at 20-30 ℃ at a shearing speed of 30-50r/min for 30-60min, prepressing and forming under 10-16MPa, performing gradient heating and curing, performing heat preservation reaction at 60-80 ℃ for 1-2h, performing heat preservation reaction at 80-110 ℃ for 2-3h, performing heat preservation reaction at 110-130 ℃ for 1-2h, and curing and forming to obtain the silica gel composite material with high heat conductivity and low dielectric property.
7. The preparation method of the silica gel composite material with high heat conductivity and low dielectric property as claimed in claim 1, wherein the silica gel matrix is composed of hydrogen-containing silicone oil, vinyl silicone oil and platinum catalyst, the mass ratio of the hydrogen-containing silicone oil to the vinyl silicone oil to the platinum catalyst is 1:3-12, the mass ratio of the composite filler to the silica gel matrix is 1:3-12, the three-dimensional filler comprises at least one of spherical alumina, boron nitride microspheres and silica hollow microspheres, the dosage of the three-dimensional filler is 10-40% of the mass of the two-dimensional filler, and the particle size of the three-dimensional filler is 50-500nm.
8. A high thermal conductivity and low dielectric silica gel composite material, which is prepared by the preparation method of the high thermal conductivity and low dielectric silica gel composite material according to any one of claims 1 to 7, and is characterized by comprising a two-dimensional filler with a transition layer coated on the surface, a one-dimensional filler embedded in the transition layer, a three-dimensional filler contacted with the outer surface of the transition layer and a silica gel matrix.

Description

Silica gel composite material with high heat conductivity and low dielectric property and preparation method thereof Technical Field The invention relates to the technical field of polymer composite materials, in particular to a silica gel composite material with high heat conductivity and low dielectric property and a preparation method thereof. Background The heat conducting gasket is used as an important interface heat management material, is widely applied between electronic components and a radiator, plays a key role in filling gaps and transferring heat, and the overall heat dissipation efficiency is directly affected by the comprehensive performance of the heat conducting gasket. At present, the common heat-conducting gasket is mostly made of polymer such as silicon rubber and the like as a matrix and is filled with heat-conducting filler such as boron nitride, aluminum oxide and the like. However, such conventional materials face significant contradictions in the synergistic optimization of multiple performance indexes. In order to improve the heat conductivity, the filler content is generally required to be greatly increased, but the density of the gasket is often increased, the dielectric constant is increased, the mechanical strength is reduced, and the flexibility is poor, otherwise, if the filler content is reduced to keep the density and the dielectric property low, the heat conductivity is difficult to meet the requirement of high-power heat dissipation. In the existing silica gel composite material, fillers with different dimensions are generally introduced into a system by adopting a simple physical mixing or surface coupling agent modification mode, and each filler exists in a matrix in a mutually independent dispersion state. In the mode, stable connection interfaces are lacked between fillers with different dimensions, one-dimensional fillers are difficult to form effective lap joint between two-dimensional fillers, and most of the contact between the three-dimensional fillers and the two-dimensional fillers is local contact or point contact, so that the contact relationship between the fillers is unstable, and a continuous and controllable filler connection network is difficult to form inside the material. In addition, in order to improve the interfacial compatibility between the filler and the silica gel matrix, in the prior art, the filler with different dimensions is generally subjected to modification treatment by a silane coupling agent, so that an organic functional layer is introduced into the surface of the filler. The method can improve the dispersibility of the fillers in the matrix, but simultaneously forms an organic coating layer on the surfaces of the fillers, so that the direct contact interface between the fillers is isolated by the organic layer, and under the condition that a plurality of fillers are respectively modified and mixed, the contact interface between the fillers with different dimensions mainly occurs between the organic modified layers on the surfaces of the fillers, and the fillers are difficult to form a stable contact relationship, so that the structural connection between the fillers with different dimensions is further weakened. Disclosure of Invention In view of the above, the invention provides a silica gel composite material with high heat conductivity and low dielectric property and a preparation method thereof, and solves the technical problems of poor contact effect and low binding force of fillers with different dimensions in the existing silica gel composite material, which cause the reduction of dielectric property and heat conduction effect. The technical scheme of the invention is realized as follows: a preparation method of a silica gel composite material with high heat conductivity and low dielectric property comprises the following steps: S1, adding a two-dimensional filler into an acid ester aqueous solvent, regulating the pH value to a preset range, and performing hydrolytic condensation reaction to deposit the surface of the two-dimensional filler to form a transition layer, so as to obtain a primary product; S2, modifying the transition layer of the primary product to form a pore structure, and adding one-dimensional filler in the modification process to enable the one-dimensional filler to be in the pore structure of the transition layer, so as to obtain a built-in material; And S3, adding the three-dimensional filler into the embedded material, stirring and mixing to obtain a composite filler, uniformly mixing the composite filler with the silica gel matrix, and curing and forming to obtain the silica gel composite material with high heat conductivity and low dielectric property. In this technical solution, further, step S1 includes: S1.1, adding a two-dimensional filler into a solvent containing a precursor, performing ultrasonic dispersion, adding a regulator to adjust the pH value until the pH value reaches a preset pH value, an