1. A preparation method of a low-filling high-thermal-conductivity polymer composite material is characterized in that molten polyethylene glycol is filled into a porous structure of expanded graphite to form a polyethylene glycol/expanded graphite blend A by utilizing the high thermal conductivity and the porous structure characteristics of carbon material expanded graphite; then blending the heat-conducting filler of the other component with epoxy resin to form a component B; then blending the component A and the component B, and curing to form the required composite material; the method comprises the following specific steps:

(1) firstly, weighing a certain amount of polyethylene glycol polymer, placing the polyethylene glycol polymer in an oven to be melted at the temperature of 80-120 ℃, transferring the completely melted polyethylene glycol to a heating table, stirring at the constant temperature of 80-120 ℃, then slowly adding expanded graphite in the stirring process, uniformly stirring, performing vacuum adsorption in a vacuum drying oven, and cooling to obtain a polyethylene glycol/expanded graphite blend A;

(2) weighing a certain amount of epoxy monomer, curing agent and other additives in a certain metering ratio, adding insulating flaky fillers of other components, and stirring for 10-60 min; and (2) then blending with the polyethylene glycol/expanded graphite blend A prepared in the step (1), continuously stirring for 10-30min, then pouring into a mould, and curing to obtain the prepared sample.

2. The preparation method according to claim 1, wherein the inorganic filler accounts for less than 30% of the low-filled high-thermal-conductivity polymer composite by mass, and the prepared low-filled high-thermal-conductivity polymer composite has a thermal conductivity of more than 2.0W m^-1 K^-1。

3. The process according to claim 1, wherein the polyethylene glycol in step (1) has a molecular weight of 1000 to 20000, the expanded graphite in step (1) is a carbon material having a porous structure obtained by an expansion method from micro graphite flakes, and the mass ratio of the polyethylene glycol to the expanded graphite is 1: 7-12.

4. The preparation method according to claim 1, characterized in that the certain metering ratio in the step (2) is a ratio calculated according to the functional groups of the epoxy resin monomer and the functional groups of the curing agent, and the other auxiliary agents mainly comprise curing accelerators, and the dosage ratio is 0.01-5% of the mass of the epoxy monomer.

5. The process according to claim 1, wherein said epoxy monomer in the step (2) is selected from the group consisting of bisphenol A type epoxy resins and bisphenol F type epoxy resins, and said curing agent is selected from the group consisting of primary amine type curing agents, tertiary amine type curing agents and acid anhydride type curing agents.

6. The method according to claim 1, wherein said insulating flake filler of the other component in step (2) is one or more selected from the group consisting of boron nitride, aluminum oxide and aluminum nitride heat conductive fillers.

7. The low-filled high-thermal-conductivity polymer composite material prepared by the preparation method of any one of claims 1 to 6 is characterized by having good phase change energy storage effect and phase change stability.

Background

With the miniaturization of electronic packaging technology and the development of various technologies such as electronic chips, the heat dissipation requirements of electronic devices are higher and higher. The polymer composite material has the advantages of simple process, light weight, good chemical resistance and the like, so the polymer composite material is widely applied to the field of heat dissipation of modern products, and common polymer heat conduction materials comprise heat conduction gaskets, heat conduction pouring sealants, heat conduction gels, heat conduction plastics and the like. However, most of the polymers have low thermal conductivity coefficient, and cannot meet the requirement of the current products on thermal conductivity. Common polymer materials, such as epoxy, polyamide, polyurethane, silicone rubber, etc., generally have thermal conductivities of 0.20W m^-1 K^-1Left and right. Therefore, the heat conductivity is generally improved by adding the heat conductive filler, and higher heat conductivity is obtained. The heat conductive filler is usually made of ceramic materials such as alumina, boron nitride, and aluminum nitride, and carbon materials including graphite flakes, expanded graphite, graphene, and carbon fiber are also usually used as the heat conductive filler. At present, the preparation of high-thermal-conductivity polymer-based composite materials usually needs to be filled with high-filling-amount thermal conductive powder, and the high-filling-amount powder easily causes the defects of difficult polymer forming, damaged mechanical properties and the like, so that the search for realizing a high thermal conductivity coefficient under a low filling amount is an important direction in the field of polymer thermal conductivity.

Disclosure of Invention

The invention aims to provide a low-filling high-thermal-conductivity polymer composite material and a preparation method thereof

In order to realize the purpose of the invention, the specific technical scheme is as follows:

a low-filling high-thermal conductivity polymer composite material and a preparation method thereof comprise the following steps:

(1) firstly weighing a certain amount of polyethylene glycol polymer, placing the polyethylene glycol polymer in an oven to be melted at the temperature of 80-120 ℃, transferring the polyethylene glycol which is completely melted into a heating table to be stirred at the constant temperature (80-120 ℃), then slowly adding the expanded graphite in the stirring process, carrying out vacuum adsorption in a vacuum drying oven after uniformly stirring, and cooling to obtain the polyethylene glycol/expanded graphite blend A.

(2) Weighing a certain amount of epoxy monomer, curing agent and other additives in a certain metering ratio, adding insulating flaky filler of other components, and stirring for 10-60 min. And then blending with the component A, continuously stirring for 10-30min, pouring into a mold, and curing to obtain the prepared sample.

The inorganic filler in the low-filling high-thermal conductivity polymer composite material accounts for less than 30% of the mass of the composite material, and the thermal conductivity coefficient of the prepared thermal conductivity material is more than 2.0W m^-1 K^-1。

The polyethylene glycol in the step 1 is a carbon material with a porous structure, the molecular weight of the polyethylene glycol is between 1000 and 20000, the expanded graphite micro-graphite sheet is obtained by an expansion method, and the mass ratio of the polyethylene glycol to the expanded graphene is 1: 7-12.

The certain metering ratio in the step 2 is a ratio calculated according to the epoxy resin monomer functional group and the curing agent functional group, and the auxiliary agent mainly comprises a curing accelerator, and the dosage ratio is 0-5% of the epoxy mass.

The epoxy resin in the step 2 comprises bisphenol A epoxy resin, bisphenol F epoxy resin and the like, and the curing agent comprises primary amine curing agent, tertiary amine curing agent and anhydride curing agent.

The insulating flaky filler of other components in the step 2 comprises one or more of heat-conducting fillers of different flaky boron nitride, aluminum oxide, aluminum nitride and the like.

According to the invention, by utilizing the characteristics of high thermal conductivity and porous structure of the carbon material expanded graphite, the molten polyethylene glycol is firstly filled into the porous structure of the expanded graphite to form a polyethylene glycol/expanded graphite blend A. Then blending the heat-conducting filler of the other component with epoxy resin to form a component B. Then the A component and the B component are blended and cured to form the required composite material.

After the technical scheme is adopted, the invention has the following beneficial effects:

the invention utilizes two heat-conducting fillers and adopts a two-component blending method, on one hand, the expanded graphite with a worm-shaped structure can form a heat-conducting channel, and on the other hand, after the component B is added, the flaky heat-conducting fillers can be attached to the surface of the expanded graphite to form a double-structure channel, so that the expanded graphite has higher heat conductivity coefficient under lower filling. In addition, in the preparation process, because the porous structure of the expanded graphite adsorbs a large amount of polyethylene glycol, the polyethylene glycol has excellent phase change energy storage capacity, and in the added component B, the flaky heat-conducting filler and the cross-linked epoxy network structure can block leakage of the polyethylene glycol during solid-liquid conversion, so that the prepared heat-conducting material has good phase change energy storage effect and phase change stability.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. It is intended that all modifications or alterations to the methods, procedures or conditions of the present invention be made without departing from the spirit or essential characteristics thereof.

Example 1

(1) Weighing 144g of polyethylene glycol polymer, placing the polyethylene glycol polymer in a drying oven at 100 ℃ for melting, transferring the polyethylene glycol completely melted into a heating table, stirring at 120 ℃, slowly adding 16g of expanded graphite in the stirring process, uniformly stirring, performing vacuum adsorption in a vacuum drying oven at 120 ℃, and cooling to obtain a polyethylene glycol/expanded graphite blend A.

(2) Weighing epoxy monomer E5180 g and polyamide curing agent A95064 g, adding 96g of flaky boron nitride, stirring for 20min, adding polyethylene glycol/expanded graphite blend component A, continuously stirring for 30min, pouring into a mold, and curing to obtain a prepared sample, wherein experiments on the sample prove that: has good phase-change energy storage effect and phase-change stability.

Example 2

(1) Weighing 144g of polyethylene glycol polymer, placing the polyethylene glycol polymer in a drying oven at 100 ℃ for melting, transferring the polyethylene glycol completely melted into a heating table, stirring at 120 ℃, slowly adding 16g of expanded graphite in the stirring process, uniformly stirring, performing vacuum adsorption in a vacuum drying oven at 120 ℃, and cooling to obtain a polyethylene glycol/expanded graphite blend A.

(2) Weighing epoxy monomer E44100 g, methylhexahydrophthalic anhydride 120g and accelerator 2-ethyl-4-methylimidazole 0.5g, then adding 96g of flaky boron nitride, stirring for 20min, adding polyethylene glycol/expanded graphite blend component A, continuously stirring for 30min, pouring into a mold, and curing to obtain the prepared sample.

Example 3

(1) Firstly weighing 100g of polyethylene glycol polymer, placing the polyethylene glycol polymer in a 120 ℃ oven for melting, transferring the polyethylene glycol completely melted into a heating table, stirring at 100 ℃, then slowly adding 8g of expanded graphite in the stirring process, uniformly stirring, performing vacuum adsorption in a vacuum drying oven at 100 ℃, and cooling to obtain a polyethylene glycol/expanded graphite blend A.

(2) Weighing epoxy monomer E44100 g and polyamide curing agent A95080 g, adding 50g of flaky aluminum nitride, stirring for 50min, adding polyethylene glycol/expanded graphite blend component A, continuously stirring for 20min, pouring into a mold, and curing to obtain a prepared sample, wherein experiments on the sample prove that: has good phase-change energy storage effect and phase-change stability.

Example 4

(1) Weighing 90g of polyethylene glycol polymer, placing the polyethylene glycol polymer in an oven at 80 ℃ for melting, transferring the polyethylene glycol completely melted to a heating table for stirring at 90 ℃, slowly adding 10g of expanded graphite in the stirring process, uniformly stirring, performing vacuum adsorption in a vacuum drying oven at 100 ℃, and cooling to obtain a polyethylene glycol/expanded graphite blend A.

(2) Weighing epoxy monomer E44100 g and polyamide curing agent A95080 g, adding 80g of flaky alumina, stirring for 50min, adding polyethylene glycol/expanded graphite blend component A, continuously stirring for 20min, pouring into a mold, and curing to obtain a prepared sample, wherein experiments on the sample prove that: has good phase-change energy storage effect and phase-change stability.

Example 5

(1) Weighing 144g of polyethylene glycol polymer, placing the polyethylene glycol polymer in a drying oven at 100 ℃ for melting, transferring the polyethylene glycol completely melted into a heating table, stirring at 120 ℃, slowly adding 16g of expanded graphite in the stirring process, uniformly stirring, performing vacuum adsorption in a vacuum drying oven at 120 ℃, and cooling to obtain a polyethylene glycol/expanded graphite blend A.

(2) Weighing 25g of epoxy monomer E51100 g and curing agent diaminodiphenylmethane, then adding 80g of flaky boron nitride, stirring for 60min, adding the polyethylene glycol/expanded graphite blend A component, continuously stirring for 30min, pouring into a mold, and curing to obtain a prepared sample, wherein the sample experiment proves that: has good phase-change energy storage effect and phase-change stability.