Highly thermally conductive polycarbonate-based composite material and method of making the same

Abstract

The application provides a high-thermal-conductivity polycarbonate-based composite material and a preparation method thereof, and belongs to the technical field of functional polycarbonate-based composite materials. The method comprises the following steps: immersing a polycarbonate (PC) film in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide to obtain a hydroxylated PC film, obtaining a functionalized PC film, ionization treatment, obtaining a modified PC film, and obtaining a high-thermal-conductivity polycarbonate film. The size and thickness of the polycarbonate film prepared by the method are controllable and can be adjusted according to the preparation process and preparation conditions. The coated functional filler presents high orientation in the plane under the heat pressing process, and the coating of the functional filler helps the rod-like zinc oxide to be oriented along the out-of-plane direction, so that the thermal conductivity coefficient of the polycarbonate film is improved.

Description

Technical Field

[0001] This invention relates to a high thermal conductivity polycarbonate-based composite material and its preparation method, belonging to the technical field of functional polycarbonate-based composite materials. Background Technology

[0002] With the development and advancement of science and technology, and the arrival of the 5G era, electronic devices have also rapidly developed and become more widespread, moving towards miniaturization and integration. Heat dissipation has thus become a crucial factor affecting the lifespan and stability of electronic devices, leading to increased demands on the thermal conductivity of materials. Polycarbonate, with its excellent mechanical and processing properties, is widely used as a matrix material for thermally conductive polymers. However, polycarbonate has a very low thermal conductivity, necessitating methods to improve its thermal conductivity.

[0003] Currently, there are two main methods to improve the thermal conductivity of polycarbonate-based composites: 1) preparing intrinsically thermally conductive polymers; and 2) preparing filled thermally conductive polymers. Among them, filled polymers achieve high thermal conductivity by adding fillers with high thermal conductivity, such as metals, metal oxides, carbon-based materials, and ceramic-based materials. This preparation method is low in cost, easy to process and mold, and industrialized.

[0004] Chinese patent CN112480447A (published on March 12, 2021) discloses a polyimide film with high out-of-plane thermal conductivity and its preparation method. This method prepares a polyimide film with high thermal conductivity both inside and outside the plane under the action of an electric field and rollers; however, the operating conditions of this method are relatively demanding.

[0005] Chinese patent CN1155625938A (publication date January 20, 2023) discloses a boron nitride thermally conductive pad with high orientation and high out-of-plane thermal conductivity, its preparation method, and its application. This method prepares a highly oriented boron nitride-based thin film using electrospinning, and then hot-presses and cuts the multilayer stacked films to obtain the thermally conductive pad. Because the cutting direction is perpendicular to the direction of the film's trajectory, the pad exhibits excellent out-of-plane thermal conductivity. However, this method using electrospinning carries significant operational risks.

[0006] Therefore, there is an urgent need in the field for a method to prepare high thermal conductivity polycarbonate-based composite materials that requires low operating conditions and is safe. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of high conditions and dangerous operation in the preparation methods of high thermal conductivity polycarbonate-based composite materials in the prior art.

[0008] To address the aforementioned problems, the present invention provides a high thermal conductivity polycarbonate-based composite material and its preparation method.

[0009] In a first aspect, the present invention provides a method for preparing a high thermal conductivity polycarbonate-based composite material, comprising the following steps:

[0010] Step 1: The polycarbonate (PC) film obtained by laboratory hot pressing is immersed in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide. The film is repeatedly rinsed with deionized water until neutral and then dried to obtain hydroxylated PC film.

[0011] Step 2: Immerse the hydroxylated PC film obtained in Step 1 in a solution of functional filler and deionized water. Rinse the film with deionized water and dry it to obtain the functionalized PC film.

[0012] Step 3: Immerse the functionalized PC film obtained in Step 2 in a mixed solution of zinc acetate and isopropanol to coat the surface of the functionalized PC film with zinc acetate. Then rinse it with deionized water, dry it, and then raise the oven temperature to form zinc ions from the zinc acetate for ionization treatment to obtain the ionized functionalized PC film.

[0013] Step 4: Place the ionized functional PC film obtained in Step 3 into a zinc nitrate and deionized water solution for a solvothermal reaction. Zinc ions grow autonomously along the 001 crystal plane to form highly oriented zinc oxide nanorods. After rinsing off excess zinc oxide with deionized water, dry the film to obtain the modified PC film.

[0014] Step 5: Alternately lay the modified PC film obtained in Step 4 and the PC film obtained by laboratory hot pressing in the mold, with both the upper and lower surfaces being PC film, and perform hot pressing to obtain a high thermal conductivity polycarbonate film.

[0015] Preferably, in step 1, the volume ratio of concentrated sulfuric acid to 30% hydrogen peroxide is 7:3-5:5, the thickness of the polycarbonate (PC) film is 0.05-0.1 mm, the soaking time is 30-60 minutes, and the drying temperature is 80-100℃.

[0016] Preferably, in step 2, the functional filler is silicon nitride, hollow carbon spheres, or carbon nitride, the mass ratio of the functional filler to deionized water is 1:20-100, the drying temperature is 80-100℃, and the volume of the functional filler and the deionized water solution is 100mL.

[0017] Preferably, in step 3, the mass ratio of zinc acetate to isopropanol is 1:3.3-33, the mass ratio of zinc nitrate to deionized water is 1:3.3-33, and the volume of the zinc acetate and isopropanol mixed solution is 100 mL.

[0018] Preferably, in step 3, the soaking time is 30-120 minutes, the ionization treatment temperature is 100-120℃ and the time is 1-3 hours, the drying temperature is 80℃ and the drying time is 30-60 minutes.

[0019] Preferably, in step 4, the solvothermal reaction temperature is controlled at 60-90℃, the volume of zinc nitrate and deionized water solution is 100mL, the solvothermal reaction time is 1-5 hours, the drying temperature is 80-100℃, and the thickness of the modified PC film is 0.06-0.12mm.

[0020] Preferably, in step 4, zinc oxide nanorods are preferentially grown in the direction perpendicular to the PC, and the orientation degree of the zinc oxide nanorods is 70-90°, with an aspect ratio of 10:(1-5).

[0021] Preferably, in step 5, the hot pressing temperature is 250-280℃, the pressure is 0.5-1.5MPa, the time is 15-60 minutes, and the thickness of the high thermal conductivity polycarbonate film is 0.2-0.5mm.

[0022] In a second aspect, the present invention provides a high thermal conductivity polycarbonate-based composite material prepared by the above method, having a thermal conductivity of 0.7-1.5 W / m·K, and the size and thickness of the film can be adjusted as needed.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The size and thickness of the polycarbonate film prepared by this invention are controllable and can be adjusted according to the preparation process and preparation conditions.

[0025] 2. In this invention, the hydroxylated polycarbonate film provides hydroxyl groups to facilitate the subsequent coating and growth of functional fillers.

[0026] 3. The functional filler coated in this invention exhibits high in-plane orientation under hot pressing process, and the coating of functional filler helps the rod-shaped zinc oxide to be oriented in the out-of-plane direction, thereby improving the thermal conductivity of the polycarbonate film. Attached Figure Description

[0027] Figure 1 Microstructure of the modified polycarbonate film prepared in Example 1 Detailed Implementation

[0028] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings:

[0029] like Figure 1 As shown, the present invention provides a high thermal conductivity polycarbonate-based composite material and its preparation method.

[0030] Example 1:

[0031] (1) A polycarbonate (PC) film with a thickness of 0.05 mm was immersed in a mixed solution of 98% concentrated sulfuric acid / 30% hydrogen peroxide for 3 minutes. The film was rinsed repeatedly with deionized water until neutral and then dried in an oven at 80°C to obtain a hydroxylated PC film.

[0032] (2) The hydroxylated PC film obtained in step (1) is immersed in 100 mL of hollow carbon spheres / deionized water solution (where the mass ratio of hollow carbon spheres to deionized water is 1:100) for 30 minutes. The film is then rinsed with deionized water and dried in an oven at 80°C to obtain the functionalized PC film.

[0033] (3) The functionalized PC film obtained in step (2) is immersed in 100 mL of zinc acetate / isopropanol mixed solution (where the mass ratio of zinc acetate to isopropanol is 1:33) for 30 minutes, then rinsed with deionized water, and dried in an oven at 80°C for 30 minutes. After that, the oven temperature is increased to 100°C for ionization treatment for 1 hour.

[0034] (4) The ionized PC film obtained in step (3) is placed in 100 mL of zinc nitrate / deionized water solution (where the mass ratio of zinc nitrate to deionized water is 1:33) and reacted for 1 hour. After rinsing off the excess zinc oxide with deionized water, it is dried in an oven at 80°C to obtain a modified PC film with a thickness of about 0.06 mm.

[0035] (5) The modified PC film obtained in step (4) is alternately laid in the mold with PC film on both the upper and lower surfaces. There are 2 layers of modified PC film and 3 layers of PC film. The hot pressing temperature is 250℃ and the pressure is maintained at 0.5 MPa for 45 minutes to obtain a high thermal conductivity polycarbonate film with a thickness of about 0.25 mm.

[0036] Tests showed that the zinc oxide nanorods had an orientation degree of 72.3° and an aspect ratio of approximately 10:5. Compared to the polycarbonate film, the thermally conductive polycarbonate film had a thermal conductivity of 0.76 W / m·K.

[0037] Example 2:

[0038] (1) A polycarbonate (PC) film with a thickness of 0.05 mm was immersed in a mixed solution of 98% concentrated sulfuric acid / 30% hydrogen peroxide for 30 minutes. The film was repeatedly rinsed with deionized water until neutral and then dried in an oven at 80°C to obtain a hydroxylated PC film.

[0039] (2) The hydroxylated PC film obtained in step (1) is placed in 100 mL of silicon nitride / deionized water solution (where the mass ratio of silicon nitride to deionized water is 1:100) and soaked for 30 minutes. The film is then rinsed with deionized water and dried in an oven at 80°C to obtain the functionalized PC film.

[0040] (3) The functionalized PC film obtained in step (2) is immersed in 100 mL of zinc acetate / isopropanol mixed solution (where the mass ratio of zinc acetate to isopropanol is 1:10) for 30 minutes, then rinsed with deionized water, and dried in an oven at 80°C for 30 minutes. After that, the oven temperature is increased to 120°C for ionization treatment for 1 hour.

[0041] (4) The ionized PC film obtained in step (3) is placed in 100 mL of zinc nitrate / deionized water solution (where the mass ratio of zinc nitrate to deionized water is 1:10) and reacted for 2 hours. After rinsing off the excess zinc oxide with deionized water, it is dried in an oven at 80°C to obtain a modified PC film with a thickness of about 0.06 mm.

[0042] (5) The modified PC film obtained in step (4) is alternately laid in the mold with PC film on both the upper and lower surfaces. There are 4 layers of modified PC film and 5 layers of PC film. The hot pressing temperature is 250℃ and the process is carried out under a pressure of 0.5Mpa for 30 minutes to obtain a high thermal conductivity polycarbonate film with a thickness of about 0.5mm.

[0043] Tests showed that the zinc oxide nanorods had an orientation degree of 78.6° and an aspect ratio of approximately 10:3. Compared to the polycarbonate film, the thermally conductive polycarbonate film had a thermal conductivity of 0.93 W / m·K.

[0044] Example 3:

[0045] (1) A 0.1 mm thick polycarbonate (PC) film was immersed in a 98% concentrated sulfuric acid / 30% hydrogen peroxide mixed solution for 60 minutes. The film was repeatedly rinsed with deionized water until neutral and then dried in an oven at 80°C to obtain a hydroxylated PC film.

[0046] (2) The hydroxylated PC film obtained in step (1) is immersed in 100 mL of silicon nitride / deionized water solution (where the mass ratio of silicon nitride to deionized water is 1:100) for 30 minutes. The film is then rinsed with deionized water and dried in an oven at 80°C to obtain the functionalized PC film.

[0047] (3) The functionalized PC film obtained in step (2) is immersed in 100 mL of zinc acetate / isopropanol mixed solution (where the mass ratio of zinc acetate to isopropanol is 1:10) for 30 minutes, then rinsed with deionized water, and dried in an oven at 80°C for 30 minutes. After that, the oven temperature is increased to 100°C for ionization treatment for 1 hour.

[0048] (4) The ionized PC film obtained in step (3) is placed in a 0.1% zinc nitrate / deionized aqueous solution (where the mass ratio of zinc nitrate to isopropanol is 1:10) and reacted for 2 hours. After rinsing off the excess zinc oxide with deionized water, it is dried in an oven at 80°C to obtain a modified PC film with a thickness of about 0.1 mm.

[0049] (5) The modified PC film obtained in step (4) is alternately laid in the mold with PC film on both the upper and lower surfaces. There are 2 layers of modified PC film and 3 layers of PC film. The hot pressing temperature is 260℃ and the pressure is maintained at 0.5Mpa for 30 minutes to obtain a high thermal conductivity polycarbonate film with a thickness of about 0.5mm.

[0050] Tests showed that the zinc oxide nanorods had an orientation degree of 84.7° and an aspect ratio of approximately 10:3. Compared to the polycarbonate film, the thermally conductive polycarbonate film had a thermal conductivity of 1.15 W / m·K.

[0051] Example 4:

[0052] (1) A polycarbonate (PC) film with a thickness of 0.1 mm was immersed in a mixed solution of 98% concentrated sulfuric acid / 30% hydrogen peroxide for 60 minutes. The film was rinsed repeatedly with deionized water until neutral and then dried in an oven at 100°C to obtain a hydroxylated PC film.

[0053] (2) The hydroxylated PC film obtained in step (1) is immersed in 100 mL of hollow carbon spheres / deionized water solution (where the mass ratio of hollow carbon spheres to deionized water is 1:20) for 60 minutes. The film is then rinsed with deionized water and dried in an oven at 80°C to obtain the functionalized PC film.

[0054] (3) The functionalized PC film obtained in step (2) is immersed in 100 mL of zinc acetate / isopropanol mixed solution (where the mass ratio of zinc acetate to isopropanol is 1:10) for 30 minutes, then rinsed with deionized water, and dried in an oven at 80°C for 30 minutes. After that, the oven temperature is increased to 120°C for ionization treatment for 1 hour.

[0055] (4) The ionized PC film obtained in step (3) is placed in 100 mL of zinc nitrate / deionized water solution (where the mass ratio of zinc nitrate to isopropanol is 1:10) and reacted for 2 hours. After rinsing off the excess zinc oxide with deionized water, it is dried in an oven at 80°C to obtain a modified PC film with a thickness of about 0.1.

[0056] (5) The modified PC film obtained in step (4) is alternately laid in the mold with PC film on both the upper and lower surfaces. There are 2 layers of modified PC film and 3 layers of PC film. The hot pressing temperature is 280℃ and the pressure is maintained at 1.5 MPa for 15 minutes to obtain a high thermal conductivity polycarbonate film with a thickness of about 0.5 mm.

[0057] Tests showed that the zinc oxide nanorods had an orientation degree of 88.6° and an aspect ratio of approximately 10:1. Compared to the polycarbonate film, the thermally conductive polycarbonate film had a thermal conductivity of 1.46 W / m·K.

[0058] Comparative Example 1:

[0059] (1) A polycarbonate (PC) film with a thickness of 0.05 mm was immersed in a mixed solution of 98% concentrated sulfuric acid / 30% hydrogen peroxide for 60 minutes. The film was repeatedly rinsed with deionized water until neutral and then dried in an oven at 80°C to obtain a hydroxylated PC film.

[0060] (2) The hydroxylated PC film obtained in step (1) is immersed in 100 mL of zinc acetate / isopropanol mixed solution (where the mass ratio of zinc acetate to isopropanol is 1:10) for 30 minutes, then rinsed with deionized water, and dried in an oven at 80°C for 30 minutes. After that, the oven temperature is increased to 120°C for ionization treatment for 1 hour.

[0061] (3) The ionized PC film obtained in step (2) was placed in 100 mL of zinc nitrate / deionized water solution (where the mass ratio of zinc nitrate to isopropanol was 1:10) and reacted for 2 hours. After rinsing off the excess zinc oxide with deionized water, the film was dried in an oven at 80°C to obtain a modified PC film with a thickness of about 0.06 mm.

[0062] The modified PC film obtained in step (4) is alternately laid in the mold with PC film on both the upper and lower surfaces. There are 2 layers of modified PC film and 3 layers of PC film. The hot pressing temperature is 250℃ and the pressure is maintained at 0.5Mpa for 30 minutes to obtain a common thermally conductive polycarbonate film with a thickness of about 0.25mm.

[0063] Tests showed that the zinc oxide nanorods had an orientation degree of 64.3° and an aspect ratio of approximately 10:5. Compared to polycarbonate films, the thermal conductivity of ordinary thermally conductive polycarbonate films is 0.57 W / m·K.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a high thermal conductivity polycarbonate-based composite material, characterized in that, Includes the following steps: Step 1: The polycarbonate (PC) film obtained by laboratory hot pressing is immersed in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide. The film is repeatedly rinsed with deionized water until neutral and then dried to obtain hydroxylated PC film. Step 2: Immerse the hydroxylated PC film obtained in Step 1 in 100 mL of a functional filler and deionized water solution. Rinse the film with deionized water and dry it to obtain the functionalized PC film. The functional filler is silicon nitride, hollow carbon spheres, or carbon nitride. The mass ratio of the functional filler to deionized water is 1:20-100. The drying temperature is 80-100℃. The volume of the functional filler and deionized water solution is 100 mL. Step 3: Immerse the functionalized PC film obtained in Step 2 in a mixed solution of zinc acetate and isopropanol to coat the surface of the functionalized PC film with zinc acetate. Then rinse it with deionized water, dry it, and then raise the oven temperature to form zinc ions from the zinc acetate for ionization treatment to obtain the ionized functionalized PC film. Step 4: Place the ionized functional PC film obtained in Step 3 into a zinc nitrate and deionized water solution for a solvothermal reaction. Zinc ions grow autonomously along the 001 crystal plane to form highly oriented zinc oxide nanorods. After rinsing off excess zinc oxide with deionized water, dry the film to obtain the modified PC film. Step 5: Alternately lay the modified PC film obtained in Step 4 and the PC film obtained by laboratory hot pressing in the mold, with both the upper and lower surfaces being PC film, and perform hot pressing to obtain a high thermal conductivity polycarbonate film.

2. The method for preparing the high thermal conductivity polycarbonate-based composite material as described in claim 1, characterized in that, In step 1, the volume ratio of concentrated sulfuric acid to 30% hydrogen peroxide is 7:3-5:5, the thickness of the polycarbonate (PC) film is 0.05-0.1 mm, the soaking time is 30-60 minutes, and the drying temperature is 80-100℃.

3. The method for preparing the high thermal conductivity polycarbonate-based composite material as described in claim 1, characterized in that, In step 3, the mass ratio of zinc acetate to isopropanol is 1:3.3-33, the mass ratio of zinc nitrate to deionized water is 1:3.3-33, and the volume of the mixed solution of zinc acetate and isopropanol is 100 mL.

4. The method for preparing the high thermal conductivity polycarbonate-based composite material as described in claim 1, characterized in that, In step 3, the soaking time is 30-120 minutes, the ionization treatment temperature is 100-120℃ and the time is 1-3 hours, the drying temperature is 80℃ and the drying time is 30-60 minutes.

5. The method for preparing the high thermal conductivity polycarbonate-based composite material as described in claim 1, characterized in that, In step 4, the solvothermal reaction temperature is controlled at 60-90℃, the volume of zinc nitrate and deionized water solution is 100mL, the solvothermal reaction time is 1-5 hours, the drying temperature is 80-100℃, and the thickness of the modified PC film is 0.06-0.12mm.

6. The method for preparing the high thermal conductivity polycarbonate-based composite material as described in claim 1, characterized in that, In step 4, zinc oxide nanorods preferentially grow in the direction perpendicular to PC, with an orientation degree of 70-90° and an aspect ratio of 10:(1-5).

7. The method for preparing the high thermal conductivity polycarbonate-based composite material as described in claim 1, characterized in that, In step 5, the hot pressing temperature is 250-280℃, the pressure is 0.5-1.5MPa, the time is 15-60 minutes, and the thickness of the high thermal conductivity polycarbonate film is 0.2-0.5mm.

8. A high thermal conductivity polycarbonate-based composite material obtained by the preparation method of any one of claims 1-7, characterized in that, The thermal conductivity is 0.7-1.5 W / m·K, and the size and thickness of the film can be adjusted as needed.

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