A multifunctional flexible thermal conductive film and preparation method thereof

Abstract

The present invention relates to a multifunctional flexible thermally conductive film and a preparation method thereof, and belongs to the technical field of thermally conductive films. The first technical problem solved by the present invention is to provide a method for preparing a multifunctional flexible thermally conductive film and a multifunctional flexible thermally conductive film prepared by the method. The method for preparing a multifunctional flexible thermally conductive film of the present invention comprises the steps of mixing a filler, a thermal conductivity enhancer, a binder, and a softener and then performing injection molding, wherein the filler is vanadium extraction tailings, the thermal conductivity enhancer is graphite, and the softener is polyethylene resin. The multifunctional flexible thermally conductive film of the present invention has moderate thermal conductivity, good flexibility, and low production cost.

Description

Technical Field

[0001] The invention relates to a multifunctional flexible thermally conductive adhesive sheet and a preparation method thereof, belonging to the technical field of thermally conductive adhesive sheets. Background Art

[0002] With the rapid development of miniaturized, integrated, lightweight and digitalized industrial electronic equipment, the requirements for the heat dissipation performance of electronic equipment are becoming increasingly higher, especially in the field of aerospace, where the requirements for the lightweight, electrical insulation, mechanical properties and heat dissipation performance of electronic equipment plastic packaging materials are particularly strict. However, due to the poor thermal conductivity of the polymer itself, its thermal conductivity is about 0.1W / m·K, and the current situation requires special customization, which is costly and cannot meet the basic requirements of industrial thermal conductivity and diversification. Therefore, it is very meaningful to prepare a thermal conductive sheet with good flexibility, moderate thermal conductivity, and can be cut at will.

[0003] At present, the main method used to obtain high thermal conductivity polymer materials is to add a large amount of expensive high thermal conductivity particles into the polymer, such as patent documents CN202010209473 "A flexible high thermal conductivity polymer nanocomposite film and preparation method", CN202010234701 "A flexible high thermal conductivity interface material and preparation method thereof", CN202110564178 "A low-density flexible high thermal conductivity absorbent silicone sheet", CN202110991652 "A high-flexibility high thermal conductivity ultra-thin silicone film and preparation method thereof", CN202122836554 "A lightweight, flexible, high thermal conductivity graphene composite thermal conductive film", CN202210050447 "A flexible high thermal conductivity polymer-based composite material and preparation method thereof", CN2022 10133954 "A flexible high thermal conductivity silicone rubber composite material, its preparation method and application", CN202211073959- "A foldable, bendable and stretchable flexible high thermal conductivity film and its preparation method", CN202220462418 "A flexible high thermal conductivity film", CN202220462482 "A flexible high thermal conductivity film mounting structure", CN202221431736 "A flexible high thermal conductivity cooling pad" and others disclose the preparation of a series of thermal conductive materials. The main idea is to add a large amount of materials with good thermal conductivity such as graphene, hexagonal boron nitride and nano-metal ions into the polymer matrix. Although these materials have high thermal conductivity, the thermal conductivity enhancers used are relatively expensive, the cost is high, and the functions used are relatively single. Summary of the invention

[0004] The first technical problem to be solved by the present invention is to provide a method for preparing a multifunctional flexible thermally conductive film.

[0005] The method for preparing a multifunctional flexible thermally conductive adhesive sheet comprises the steps of mixing a filler, a thermal conductivity enhancer, a binder and a softener and then performing injection molding, wherein the filler is vanadium extraction tailings, the thermal conductivity enhancer is graphite, the softener is polyethylene resin, and the binder is prepared from the following components in parts by weight: 3-10 parts of polyvinyl alcohol, 0.0025-0.02 parts of sodium silicate, 0.0025-0.02 parts of borax, and 89.96-96.995 parts of water; the weight ratio of the filler to the thermal conductivity enhancer is 90-99:1-10, the softener is 1-2% of the mass of the binder, and the solid-liquid ratio of the filler, the thermal conductivity enhancer, the binder and the softener after mixing is 0.2-0.35 g / mL.

[0006] Furthermore, the method for preparing the multifunctional flexible thermally conductive film of the present invention comprises the following steps:

[0007] a. Heat the binder to 70-90°C, add polyethylene resin, mix well, and obtain a mixture of binder and softener;

[0008] b. Mix the vanadium extraction tailings and graphite, and then add them to the mixture of the binder and the softener prepared in step a, mix well, and obtain a mixed slurry;

[0009] c. Pour the mixed slurry into the mold, spread it evenly, cool it, and demold it to obtain a multifunctional flexible thermal conductive film.

[0010] Wherein, in the method for preparing a multifunctional flexible thermally conductive film of the present invention, the content of polyvinyl alcohol in the binder in step a is preferably 5% to 8%.

[0011] Furthermore, in order to improve the performance of the prepared multifunctional flexible thermally conductive film, in the method for preparing the multifunctional flexible thermally conductive film of the present invention, the vanadium extraction tailings in step b are preferably first crushed to pass through a 120-mesh sieve.

[0012] In the method for preparing a multifunctional flexible thermally conductive film of the present invention, the thickness of the multifunctional flexible thermally conductive film obtained in step c can be adjusted according to specific needs, for example, the thickness can be adjusted to 1 to 10 mm.

[0013] The second technical problem to be solved by the present invention is to provide a multifunctional flexible thermally conductive film prepared by the above method.

[0014] The multifunctional flexible thermally conductive adhesive sheet of the present invention has a good thermal conductivity, which can reach 0.28 to 0.52 W·m -1 ·K -1 .

[0015] The multifunctional flexible thermally conductive adhesive sheet of the present invention has a high solar energy absorption ratio, which can reach between 0.90 and 0.94.

[0016] The multifunctional flexible thermally conductive adhesive sheet of the present invention has good flexibility and has no cracks after being bent at 90 degrees for 50 times.

[0017] The multifunctional flexible thermal conductive adhesive sheet of the present invention is 900-1200W / m 2 Under solar radiation conditions, the heating rate is 1.5-2.5℃ / min, the maximum temperature under direct sunlight is ≥60℃, and under no sunlight conditions, the cooling rate is 1.9-2.5℃ / min.

[0018] Furthermore, the present invention also provides a method for recycling the multifunctional flexible thermal conductive film, which is specifically: cutting the used multifunctional flexible thermal conductive film into pieces, adding it into water at 80-90°C, stirring and heating it to turn it into slurry, and then performing injection molding again to obtain the multifunctional flexible thermal conductive film.

[0019] The beneficial effects of the present invention are as follows: based on the prior art, the present invention uses a specific preparation method to evenly disperse vanadium tailings and graphite into PVA to prepare a product with a fast heating and cooling speed (see the specific test results for details). Figure 5 and Figure 6 As shown), it has moderate thermal conductivity and good flexibility. It uses vanadium extraction tailings instead of expensive graphene and cubic boron nitride, which greatly reduces the production cost. It also has the advantages of easy molding and suitability for large-scale production. It is recyclable and will not pollute the environment. It can be widely used in thermal conductive adhesive slurry, ordinary heat absorber and heat sink and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram of the molding process of a multifunctional flexible thermally conductive adhesive sheet of the present invention;

[0021] Figure 2 It is a diagram of the process of preparing a film that can be cut according to the present invention;

[0022] Figure 3 The film prepared for the present invention is cut into different shapes;

[0023] Figure 4 This is a test diagram of the anti-bending performance in the preparation method of the present invention;

[0024] Figure 5 The figure is a temperature rise and fall process diagram of the flexible thermal conductive film prepared by the present invention;

[0025] Figure 6 The infrared imaging diagram of the temperature rise and fall process of the flexible thermal conductive film prepared by the present invention;

[0026] Figure 7 The figure is a diagram of the reshaping process of the flexible thermally conductive film prepared by the present invention. DETAILED DESCRIPTION

[0027] The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0028] Example 1

[0029] Adopt the adhesive preparation method in patent CN201410212434.8 (composite adhesive and its preparation method and use) to prepare an adhesive with a PVA content of 8% and a polyethylene resin as a softener of 1% (place a 2000mL beaker in a constant temperature oil bath at 80°C, add 1000mL of water to the beaker, add 80g of PVA to the beaker, and then add 10g of polyethylene resin, continue magnetic stirring until all the solvents are completely melted, stop stirring and set aside), weigh 0.175g of graphite and 17.325 1.5g vanadium tailings (total mass 17.5g, graphite 1%) with less than 120 mesh were mixed on A4 paper, and 50mL of the above binder was measured in a beaker and placed in a constant temperature water bath at 80°C. 17.5g of the solid mixture was added while stirring, and the mixed slurry was obtained by stirring for 30min to obtain a 0.35g / mL thermal conductive slurry. The slurry was poured into a preset molding mold, pressed into shape, and cooled at room temperature to obtain a flexible thermal conductive film with a thickness of about 5mm. The thermal conductivity of the multifunctional flexible thermal conductive film obtained in this example was 0.286W m - 1 K -1 , solar absorption ratio 0.938 (AM1.5), 1100W / m 2 The heating rate under solar energy is 2.31℃ / min, and the natural cooling rate is 2.5℃ / min.

[0030] Example 2

[0031] Adopt the adhesive preparation method in patent CN201410212434.8 (composite adhesive and its preparation method and use) to prepare an adhesive with a PVA content of 8% and a polyethylene resin as a softener of 1% (place a 2000mL beaker in a constant temperature oil bath at 80°C, add 1000mL of water to the beaker, add 80g of PVA to the beaker, and then add 10g of polyethylene resin, continue magnetic stirring until all the solvents are completely melted, stop stirring and set aside), weigh 0.875g of graphite and 16.625 1.5g vanadium tailings (total mass 17.5g, graphite 5%) with less than 120 mesh were mixed on A4 paper, and 50mL of the above binder was measured in a beaker and placed in a constant temperature water bath at 80°C. 17.5g of the solid mixture was added while stirring, and the mixed slurry was obtained by stirring for 30min to obtain a 0.35g / mL thermal conductive slurry. The slurry was poured into a preset molding mold, pressed into shape, and cooled at room temperature to obtain a flexible thermal conductive film with a thickness of about 5mm. The thermal conductivity of the multifunctional flexible thermal conductive film obtained in this example was 0.433W m - 1 K -1 , solar absorption ratio 0.934 (AM1.5), 1100W / m 2 The heating rate under solar energy irradiation is 2.05℃ / min, and the natural cooling rate is 2.21℃ / min.

[0032] Example 3

[0033] Adopt the adhesive preparation method in patent CN201410212434.8 (composite adhesive and its preparation method and use) to prepare an adhesive with a PVA content of 8% and a polyethylene resin as a softener of 1% (place a 2000mL beaker in a constant temperature oil bath at 80°C, add 1000mL of water to the beaker, add 80g of PVA to the beaker, and then add 10g of polyethylene resin, continue magnetic stirring until all the solvents are completely melted, stop stirring and set aside), weigh 1.75g ​​of graphite and 15.75g of Vanadium tailings below 120 mesh (total mass 17.5g, graphite 10%) were mixed on A4 paper, and 50mL of the above binder was measured in a beaker and placed in a constant temperature water bath at 80°C. 17.5g of the solid mixture was added while stirring, and the mixed slurry was obtained by stirring for 30min to obtain a 0.35g / mL thermal conductive slurry. The slurry was poured into a preset molding mold, pressed into shape, and cooled at room temperature to obtain a flexible thermal conductive film with a thickness of about 5mm. The thermal conductivity of the multifunctional flexible thermal conductive film obtained in this example was 0.523W m -1 K -1 , solar absorption ratio 0.926 (AM1.5), 1100W / m 2The heating rate under solar energy irradiation is 2.05℃ / min, and the natural cooling rate is 2.21℃ / min.

[0034] Example 4

[0035] First, cut 10.5g of the multifunctional flexible thermal conductive film into pieces and put them into a beaker. Add 10g of distilled water and 10-15g of adhesive into the beaker. Place the beaker in a constant temperature water bath at 80°C and stir magnetically for 20-40 minutes. Wait until all the fragments of the thermal conductive film are melted to reshape the multifunctional flexible thermal conductive film.

Claims

1. Method for preparing a multifunctional flexible thermally conductive film, Features: The invention comprises the steps of mixing a filler, a thermal conductivity enhancer, a binder and a softener and then performing injection molding, wherein the filler is vanadium extraction tailings, the thermal conductivity enhancer is graphite, the softener is polyethylene resin, and the binder is prepared from the following components in parts by weight: 3-10 parts of polyvinyl alcohol, 0.0025-0.02 parts of sodium silicate, 0.0025-0.02 parts of borax, and 89.96-96.995 parts of water; the weight ratio of the filler to the thermal conductivity enhancer is 90-99:1-10, the softener is 1-2% of the mass of the binder, and the solid-liquid ratio of the filler, the thermal conductivity enhancer, the binder and the softener after mixing is 0.2-0.35 g / mL.

2. The method for preparing a multifunctional flexible thermally conductive adhesive sheet according to claim 1, It is characterized in that The steps include: a. Heat the binder to 70-90°C, add polyethylene resin, mix well, and obtain a mixture of binder and softener; b. Mix the vanadium extraction tailings and graphite, and then add them to the mixture of the binder and the softener prepared in step a, mix well, and obtain a mixed slurry; c. Pour the mixed slurry into the mold, spread it evenly, cool it, and demold it to obtain a multifunctional flexible thermal conductive film.

3. The method for preparing a multifunctional flexible thermally conductive adhesive sheet according to claim 2, Features: The content of polyvinyl alcohol in the binder described in step a is 5% to 8%.

4. The method for preparing a multifunctional flexible thermally conductive adhesive sheet according to claim 2, Features: The vanadium extraction tailings described in step b are first crushed to pass through a 120-mesh sieve.

5. The method for preparing a multifunctional flexible thermally conductive adhesive sheet according to claim 2, Features: The thickness of the multifunctional flexible thermally conductive film obtained in step c is 1 to 10 mm.

6. A multifunctional flexible thermally conductive adhesive sheet prepared by the method according to any one of claims 1 to 5.

7. The multifunctional flexible thermally conductive adhesive sheet according to claim 6, Features: The thermal conductivity of the multifunctional flexible thermally conductive adhesive sheet is 0.28 to 0.52 W·m -1 ·K -1 ; The solar absorption ratio of the multifunctional flexible thermal conductive film is 0.90 to 0.

94.

8. The multifunctional flexible thermally conductive adhesive sheet according to claim 6, Features: The multifunctional flexible thermally conductive adhesive sheet was bent 90° for 50 times without any cracks.

9. The multifunctional flexible thermally conductive adhesive sheet according to claim 6, Features: The multifunctional flexible thermally conductive adhesive sheet has a thermal conductivity of 900 to 1200 W / m 2 Under solar radiation conditions, the heating rate is 1.5-2.5℃ / min, the maximum temperature under direct sunlight is ≥60℃, and under no sunlight conditions, the cooling rate is 1.9-2.5℃ / min.

10. A method for recycling the multifunctional flexible thermally conductive adhesive sheet according to any one of claims 6 to 9, Features: The used multifunctional flexible thermal conductive film is cut into pieces, added into water at 80-90°C, stirred and heated to become slurry, and then injection molded again to obtain the multifunctional flexible thermal conductive film.

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