CN114539756A - Carbon fiber-polycarbonate heat-conducting composite material vertically arranged and preparation method thereof - Google Patents

Abstract

The invention discloses a vertically arranged carbon fiber-polycarbonate heat-conducting composite material. It is prepared according to the following steps: taking mesophase pitch-based carbon fibers, graphitizing, and shearing to obtain a plurality of short carbon fibers; forming the short carbon fibers into a vertically arranged high-density carbon fiber array by using an electrostatic flocking method; dissolving polycarbonate granules in tetrahydrofuran to form a mixed liquid; and then pouring the mixed liquid into a vertically-arranged high-density carbon fiber array, carrying out vacuum liquid phase impregnation, and curing polycarbonate to obtain the vertically-arranged carbon fiber-polycarbonate heat-conducting composite material. The composite material takes mesophase pitch-based carbon fibers as heat-conducting fillers, and the carbon fibers are vertically arranged in the composite material, so that the heat conductivity of the composite material in the vertical direction is greatly enhanced, and the product performance is good; the preparation method is simple to operate, short in preparation period and low in requirement on equipment.

Description

A kind of vertically arranged carbon fiber-polycarbonate thermally conductive composite material and preparation method thereof

technical field

The invention relates to a thermally conductive composite material, in particular to a vertically arranged carbon fiber-polycarbonate thermally conductive composite material and a preparation method thereof.

Background technique

Due to the ever-increasing power density and consumption, thermal management has become one of the most important issues in electronic devices such as integrated circuits, and the use of heat sinks is integral to protecting modern electronics from thermal failures. Thermal management of electronic devices is difficult because conventional electronic devices are made of rigid materials with high thermal conductivity, such as metals. When the surface of the electronic device and the metal plate heat sink come into contact, perfect contact cannot be made due to the difference in height between the two surfaces. It is well known that two rigid planes only touch at three points, resulting in poor thermal contact. At present, the thermal conductivity of thermal management materials is not enough to satisfy the evolving electronic products, and currently has good thermal conductivity in the planar direction, but poor thermal performance in the vertical direction. For example, layered graphite exhibits extremely high thermal conductivity in the planar direction. Therefore, the preparation of composite materials with high thermal conductivity in the vertical direction is an important solution to solve the high density of electronic devices. However, the current traditional thermally conductive composite materials cannot achieve high thermal conductivity in the vertical direction to solve the thermal management problems caused by the increasing functional density of electronic devices.

SUMMARY OF THE INVENTION

The present invention provides a vertically arranged carbon fiber-polycarbonate thermally conductive composite material and a preparation method thereof in order to solve the above technical problems. The thermally conductive composite material utilizes mesophase pitch-based carbon fibers, which have high thermal conductivity. The carbon fibers are prepared into a vertically arranged array by an electrostatic flocking method, and then compounded with polycarbonate to prepare a high thermal conductivity thermal interface material, which can be widely used. For thermal management of electronic appliances.

To achieve the above object, the concrete steps of the technical solution adopted in the present invention are:

A vertically arranged carbon fiber-polycarbonate thermally conductive composite material, the composite material is composed of a polycarbonate matrix and chopped carbon fibers distributed in the polycarbonate matrix, and the chopped carbon fibers are a high thermal conductivity intermediate phase Pitch-based carbon fibers, the chopped carbon fibers are arranged in a vertical array in the matrix.

Preferably, the length of the chopped carbon fibers is 1-2 mm.

Preferably, the polycarbonate is aromatic bisphenol A polycarbonate.

The preparation method of the vertically arranged carbon fiber-polycarbonate thermally conductive composite material comprises the following steps:

Take mesophase pitch-based carbon fibers, undergo graphitization treatment, and then shear to obtain several chopped carbon fibers;

Using the method of electrostatic flocking to form the plurality of chopped carbon fibers into a vertically arranged high-density carbon fiber array;

Dissolve the polycarbonate particles in tetrahydrofuran to form a mixed liquid; then pour the mixed liquid into a vertically arranged high-density carbon fiber array for vacuum liquid-phase impregnation. After the polycarbonate is cured, the vertically arranged carbon fiber is obtained. Fiber-polycarbonate thermally conductive composites.

Preferably, the length of the chopped carbon fibers is 1-2 mm.

Preferably, the specific steps of the electrostatic flocking are as follows: paste a layer of polyimide glue on the upper end of the electrostatic flocking instrument, place a metal disc containing a number of chopped carbon fibers on the lower end of the instrument, and adjust the electric field The voltage is 20-40KV, and the fibers are adsorbed on the polyimide glue under the action of the electric field, showing a state of vertical arrangement, repeating many times until the fibers are covered with the entire polyimide glue.

Preferably, the electric field distance is set to 6-12 cm.

Preferably, the concentration of the polycarbonate is 20wt%-30wt%.

Preferably, the polycarbonate particles are dissolved in tetrahydrofuran by heating, and the heating temperature is 60°C.

Compared with the prior art, this specific example has the following positive effects:

The invention prepares a vertically arranged carbon fiber-polycarbonate composite material. The composite material uses mesophase pitch-based carbon fiber as a thermal conductive filler, and the carbon fibers are vertically arranged in the composite material, so that the composite material conducts heat conduction in the vertical direction. The efficiency is greatly enhanced, and the product performance is good; the preparation method is simple to operate, the production cycle is short, and the requirements for equipment are low.

Description of drawings

Fig. 1 is the electrostatic flocking device used in the present invention.

FIG. 2 is a diagram of chopped fibers in an embodiment of the present invention.

3 is a scanning electron microscope image of the vertically aligned carbon fiber/polycarbonate composite material in Example 1 of the present invention.

4 is a scanning electron microscope image of the vertically aligned carbon fiber/polycarbonate composite material in Example 2 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Example 1

Preparation of Vertically Aligned Carbon Fiber/Polycarbonate Composites:

The mesophase pitch-based carbon fibers were taken and graphitized at 3000 ℃ to obtain high thermal conductivity carbon fibers with a thermal conductivity of 900 W•m ^-1 •K ^-1 . Weigh 0.5 g of the cut fiber, and the fiber length is 1 mm. The fibers were evenly distributed on the circular iron sheet through the screen, and the electric field distance was set to 6 cm.

Paste a layer of polyimide glue on the upper end of the electrostatic flocking instrument, place the metal disc with fibers on the lower end of the instrument, and close the hatch. Turn on the instrument, adjust the voltage of the electric field to 20KV, and the fibers are adsorbed on the polyimide glue under the action of the electric field, showing a state of vertical arrangement, repeating several times until the fibers are covered with the entire polyimide glue.

5g of polycarbonate particles were dissolved in 20g of tetrahydrofuran to form a mixed solution with a certain viscosity, then the mixed resin was poured into the vertically arranged carbon fibers, put into a vacuum impregnation container, and the vacuum pump was turned on to form a vacuum environment in the container. When the polycarbonate is cured, the composite is prepared for molding.

Example 2

The mesophase pitch-based carbon fibers were taken and graphitized at 3000℃ to obtain high thermal conductivity carbon fibers with a thermal conductivity of 900W·m ^-1 •K ^-1 . Weigh 0.5 g of the cut fiber, and the fiber length is 1 mm. The fibers were evenly distributed on the circular iron sheet through the screen, and the electric field distance was set to 9 cm.

Paste a layer of polyimide glue on the upper end of the electrostatic flocking instrument, place the metal disc with fibers on the lower end of the instrument, and close the hatch. Turn on the instrument, adjust the voltage of the electric field to 20KV, and the fibers are adsorbed on the polyimide glue under the action of the electric field, showing a state of vertical arrangement, repeating several times until the fibers are covered with the entire polyimide glue.

5 g of polycarbonate particles were dissolved in 20 g of tetrahydrofuran to form a mixed liquid with a certain viscosity. Then, the mixed resin is poured into the vertically arranged carbon fibers, put into a vacuum impregnation container, and the vacuum pump is turned on to form a vacuum environment in the container. When the polycarbonate is cured, the composite is prepared for molding.

Example 3

The mesophase pitch-based carbon fibers were taken and graphitized at 3000 ℃ to obtain high thermal conductivity carbon fibers with a thermal conductivity of 900 W•m ^-1 •K ^-1 . Weigh 0.5 g of the cut fiber, and the fiber length is 1 mm. The fibers were evenly distributed on the circular iron sheet through the screen, and the electric field distance was set to 12 cm.

Paste a layer of polyimide glue on the upper end of the electrostatic flocking instrument, place the metal disc with fibers on the lower end of the instrument, and close the hatch. Turn on the instrument, adjust the voltage of the electric field to 20KV, and the fibers are adsorbed on the polyimide glue under the action of the electric field, showing a state of vertical arrangement, repeating several times until the fibers are covered with the entire polyimide glue.

5 g of polycarbonate particles were dissolved in 20 g of tetrahydrofuran, and the polycarbonate particles were dissolved in tetrahydrofuran to form a mixed liquid with a certain viscosity. Then, the mixed resin is poured into the vertically arranged carbon fibers, put into a vacuum impregnation container, and the vacuum pump is turned on to form a vacuum environment in the container. When the polycarbonate is cured, the composite is prepared for molding.

Example 4

The mesophase pitch-based carbon fibers were taken and graphitized at 3000 ℃ to obtain high thermal conductivity carbon fibers with a thermal conductivity of 900 W·m ^-1 ·K ^-1 . Weigh 0.5 g of the cut fiber, and the fiber length is 1 mm. The fibers were evenly distributed on the circular iron sheet through the screen, and the electric field distance was set to 6 cm.

Paste a layer of polyimide glue on the upper end of the electrostatic flocking instrument, place the metal disc with fibers on the lower end of the instrument, and close the hatch. Turn on the instrument, adjust the voltage of the electric field to 40KV, and the fibers are adsorbed on the polyimide glue under the action of the electric field, showing a state of vertical arrangement, repeating several times until the fibers are covered with the entire polyimide glue.

5 g of polycarbonate particles were dissolved in 20 g of tetrahydrofuran to form a mixed liquid with a certain viscosity. Then, the mixed resin is poured into the vertically arranged carbon fibers, put into a vacuum impregnation container, and the vacuum pump is turned on to form a vacuum environment in the container. When the polycarbonate is cured, the composite is prepared for molding.

Example 5

The mesophase pitch-based carbon fibers were taken and graphitized at 3000 ℃ to obtain high thermal conductivity carbon fibers with a thermal conductivity of 900 W·m ^-1 ·K ^-1 . Weigh 0.5 g of the cut fiber, and the fiber length is 2 mm. The fibers were evenly distributed on the circular iron sheet through the screen, and the electric field distance was set to 9 cm.

Paste a layer of polyimide glue on the upper end of the electrostatic flocking instrument, place the metal disc with fibers on the lower end of the instrument, and close the hatch. Turn on the instrument, adjust the voltage of the electric field to 20KV, and the fibers are adsorbed on the polyimide glue under the action of the electric field, showing a state of vertical arrangement, repeating several times until the fibers are covered with the entire polyimide glue.

5 g of polycarbonate particles were dissolved in 20 g of tetrahydrofuran to form a mixed liquid. Then, the mixed resin is poured into the vertically arranged carbon fibers, put into a vacuum impregnation container, and the vacuum pump is turned on to form a vacuum environment in the container. When the polycarbonate is cured, the composite is prepared for molding.

Example 6

The mesophase pitch-based carbon fibers were taken and graphitized at 3000 ℃ to obtain high thermal conductivity carbon fibers with a thermal conductivity of 900 W·m ^-1 ·K ^-1 . Weigh 0.5 g of the cut fiber, and the fiber length is 1 mm. The fibers were evenly distributed on the circular iron sheet through the screen, and the electric field distance was set to 12 cm.

Paste a layer of polyimide glue on the upper end of the electrostatic flocking instrument, place the metal disc with fibers on the lower end of the instrument, and close the hatch. Turn on the instrument, adjust the voltage of the electric field to 40KV, and the fibers are adsorbed on the polyimide glue under the action of the electric field, showing a state of vertical arrangement, repeating several times until the fibers are covered with the entire polyimide glue.

5 g of polycarbonate particles were dissolved in 20 g of tetrahydrofuran to form a mixed liquid. Then, the mixed resin is poured into the vertically arranged carbon fibers, put into a vacuum impregnation container, and the vacuum pump is turned on to form a vacuum environment in the container. When the polycarbonate is cured, the composite is prepared for molding. Table 1 shows the specific formulations of Examples 1-6 and their test performance results.

Thermal conductivity test method of vertically arranged carbon fiber/polycarbonate composite material: The composite material is cut into a size of 1 cm×1 cm, and the vertical rough surface of the composite material is smoothed with sandpaper. Weigh its mass and calculate the density of the composite. The thermal diffusivity and specific heat were measured using a laser thermal conductivity meter, through the formula Tc=α×ρ×c (α is the thermal diffusivity, ρ is the density and c is the specific heat).

Table 1

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Polycarbonate Concentration (wt%) 20 20 20 20 20 20 Carbon fiber (g) 0.5 0.5 0.5 0.5 0.5 0.5 Electric field distance (cm) 6 9 12 6 9 12 Electric field voltage (KV) 20 20 20 40 20 40 Fiber length (mm) 1 1 1 1 2 1 Thermal conductivity (W·m^-1·K^-1) 12 18 19 13 15 30

It can be seen from the data comparison in Table 1 that the thermal conductivity of the composite materials obtained in Examples 1-6 is related to the electric field distance, electric field voltage and fiber length. It can be concluded that the greater the electric field voltage, the larger the electric field distance and the longer the fiber length. Small size can obtain excellent thermal conductivity, which increases the application of composite materials in electronic appliances.

Claims (9)

1. The vertically-arranged carbon fiber-polycarbonate heat-conducting composite material is characterized by consisting of a polycarbonate matrix and chopped carbon fibers distributed in the polycarbonate matrix, wherein the chopped carbon fibers are high-heat-conducting mesophase pitch-based carbon fibers, and the chopped carbon fibers are arranged in the matrix in an array manner in the vertical direction.

2. A thermally conductive composite material as claimed in claim 1 wherein said chopped carbon fibres have a length of 1 to 2 mm.

3. A thermally conductive composite material as claimed in claim 1 wherein said polycarbonate is aromatic bisphenol a polycarbonate.

4. The method for preparing a vertically aligned carbon fiber-polycarbonate heat conductive composite material according to claim 1, comprising the steps of:

taking mesophase pitch-based carbon fibers, graphitizing, and shearing to obtain a plurality of short carbon fibers; forming the short carbon fibers into a vertically arranged high-density carbon fiber array by using an electrostatic flocking method; dissolving polycarbonate granules in tetrahydrofuran to form a mixed liquid; and then pouring the mixed liquid into a vertically-arranged high-density carbon fiber array, carrying out vacuum liquid phase impregnation, and curing polycarbonate to obtain the vertically-arranged carbon fiber-polycarbonate heat-conducting composite material.

5. The method for preparing a vertically aligned carbon fiber-polycarbonate heat conductive composite material according to claim 4, wherein the chopped carbon fibers have a length of 1-2 mm.

6. The method for preparing the vertically arranged carbon fiber-polycarbonate heat-conducting composite material as claimed in claim 4, wherein the electrostatic flocking comprises the following specific steps: adhering a layer of polyimide glue on the upper end of an electrostatic flocking instrument, placing a metal wafer filled with a plurality of short-cut carbon fibers at the lower end of the instrument, adjusting the voltage of an electric field to be 20-40KV, adsorbing the fibers on the polyimide glue under the action of the electric field to present a vertically arranged state, and repeating for multiple times until the fibers are fully paved with the whole polyimide glue.

7. The method for preparing a vertically aligned carbon fiber-polycarbonate heat conductive composite material according to claim 6, wherein the electric field distance is set to 6-12 cm.

8. The method for preparing a vertically aligned carbon fiber-polycarbonate heat conductive composite material according to claim 4, wherein the concentration of the polycarbonate is 20 wt% to 30 wt%.

9. The method for preparing a vertically aligned carbon fiber-polycarbonate heat conductive composite material according to claim 4, wherein the polycarbonate particles are dissolved in tetrahydrofuran by heating at a temperature of 60 ℃.

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