Preparation method of multi-layer composite high-thermal-conductivity phase change heat storage film

Abstract

The application discloses a kind of preparation methods of multilayer composite high-thermal-conductivity phase change heat storage film, belong to the technical field of heat-conducting material, including following raw material components: organic phase change base material, expanded graphite, adhesive, organic phase change base material, expanded graphite and adhesive melt blend, granular material is prepared after crushing treatment, again through film-forming process, artificial graphite film single layer or upper and lower double-layer composite calendering obtains multilayer composite high-thermal-conductivity film piece.The multilayer composite high-thermal-conductivity film piece obtained by optimizing material ratio and process has large thickness range, low precipitation, high plane thermal conductivity coefficient, can meet the needs of different application scenarios;Production efficiency is significantly improved, and manufacturing cost is reduced;Reduce phase change material precipitation, improve stability;Enhance plane thermal conductivity coefficient, optimize heat management performance.

Description

Technical Field

[0001] This invention belongs to the field of thermal conductive materials technology, and specifically relates to a method for preparing a multilayer composite high thermal conductivity phase change thermal storage film. Background Technology

[0002] High thermal conductivity phase change materials (PCCs) are materials that store and release energy through physical and chemical means. The principle is to release latent heat through a phase change, transferring heat from a high-temperature region to a low-temperature region. PCCs have applications across various industries. In the electronics field, PCCs are used in heat dissipation systems for electronic devices, achieving efficient heat dissipation and energy storage through the material's phase change properties. However, existing methods for preparing PCC films have the following shortcomings:

[0003] (1) Low-density graphite sheet impregnation method: The thickness control is constrained by the forming density of graphite sheets. Thicker sheets have low production efficiency and the impregnation process is prone to material unevenness.

[0004] (2) Die casting / hot pressing of expanded graphite and phase change material blend: narrow thickness range, high risk of phase change material precipitation, and difficulty in improving planar thermal conductivity.

[0005] Therefore, there is an urgent need for a simple and high-performance method for preparing multilayer composite films / sheets. Summary of the Invention

[0006] This invention provides a method for preparing a multilayer composite high thermal conductivity phase change thermal storage film, aiming to solve the technical problems in the preparation of thermally conductive phase change material films in the prior art, such as limited thickness, low production efficiency, precipitation problems, and insufficient planar thermal conductivity.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a multilayer composite high thermal conductivity phase change thermal storage film, wherein the multilayer composite high thermal conductivity film includes an intermediate layer and a graphite film on its surface, and the intermediate layer includes the following raw material components:

[0009] Organic phase change substrate: 50-80 parts;

[0010] Expanded graphite: 17-48 parts;

[0011] Adhesive: 1-3 parts;

[0012] The above raw material components are melted, blended, and crushed to obtain granules; the granules used to prepare the intermediate layer are then processed into an intermediate layer using a film-forming process, and the intermediate layer is then calendered with a graphite film to obtain a multilayer composite high thermal conductivity film.

[0013] Furthermore, the organic phase change substrate is one or more of straight-chain alkanes, fatty acids, and polyethylene glycol.

[0014] Furthermore, the melting temperature of the organic phase change substrate, expanded graphite, and binder is controlled at 180℃±30℃, and they are blended for 30±10 minutes; then crushed into particles with a particle size of 0.5-1mm.

[0015] Furthermore, the film-forming process is completed using a screw extruder, a calender, and a coating device, and includes the following steps:

[0016] (1) The obtained granules are fed into a screw extruder for plasticization and extrusion to obtain intermediate material;

[0017] (2) The calender and the coating device are combined. The intermediate material enters the calender and is plasticized and calendered into a sheet intermediate layer. The calender and the coating device are combined to coat the graphite film on the surface of the sheet intermediate layer. Finally, the composite calendering is used to obtain a multi-layer composite high thermal conductivity film.

[0018] Furthermore, in step (2), the extrusion temperature of the screw extruder is 180±30℃ and the pressure is 10±5MPa, and the calender roll temperature is 80-180℃ and the pressure is 2-10MPa.

[0019] Furthermore, the graphite film is an artificial graphite film or a high-density natural graphite film, the thickness of the graphite film is 0.01-0.05mm, and the planar thermal conductivity is between 300-1900w / mk.

[0020] Furthermore, the graphite film covers one or both sides of the sheet-like intermediate layer, and a nano-thermal conductive filler is provided between the graphite film and the sheet-like intermediate layer.

[0021] Furthermore, the thickness of the multilayer composite high thermal conductivity film is 0.03-3mm, and the planar thermal conductivity can be adjusted between 100-900 W / (m·K) depending on the proportion of graphite film thickness and its own thermal conductivity.

[0022] The technological advancements achieved by this invention compared to existing technologies are as follows:

[0023] This invention involves blending an organic phase change substrate, expanded graphite, and a binder, followed by crushing to obtain granules. These granules are then laminated with a single layer or two layers of artificial graphite using a film-forming process to obtain a multilayer composite high thermal conductivity film. By optimizing material ratios and processes, this invention yields multilayer composite high thermal conductivity films with a wide thickness range, low precipitation, and high planar thermal conductivity, meeting the needs of various application scenarios. It significantly improves production efficiency, reduces manufacturing costs, minimizes phase change material precipitation, enhances stability, and improves planar thermal conductivity, thus optimizing thermal management performance. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0025] In the attached diagram:

[0026] Figure 1 A schematic diagram illustrating the working principle of the calender and coating device used in the preparation method of a multilayer composite high thermal conductivity phase change heat storage film provided in an embodiment of the present invention;

[0027] In the picture:

[0028] 00-Multi-layer composite high thermal conductivity film; 1-Screw extruder; 2-First coating device; 3-Second coating device; 4-Caliper roll. Detailed Implementation

[0029] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0030] This invention provides a method for preparing a multilayer composite high thermal conductivity phase change thermal storage film, wherein the multilayer composite high thermal conductivity film includes an intermediate layer and a graphite film on its surface, and the intermediate layer includes the following raw material components:

[0031] Organic phase change substrate: 50-80 parts;

[0032] Expanded graphite: 17-48 parts;

[0033] Adhesive: 1-3 parts;

[0034] The above raw material components are melted, blended, and crushed to obtain granules; the granules used to prepare the intermediate layer are then processed into an intermediate layer using a film-forming process, and the intermediate layer is then calendered with a graphite film to obtain a multilayer composite high thermal conductivity film.

[0035] In the specific manufacturing process, the organic phase change substrate is made from one or more of linear alkanes, fatty acids, and polyethylene glycol; the binder is made from polyolefins. The melting temperature of the organic phase change substrate, expanded graphite, and binder is controlled at 180℃±30℃, and they are blended for 30±10 minutes; then crushed into particles with a particle size of 0.5-1mm.

[0036] The film-forming process is accomplished by combining a screw extruder, a calender, and a coating unit, with the combined equipment such as... Figure 1 As shown, this embodiment has two coating devices, namely a first coating device 2 and a second coating device 3, and includes the following steps:

[0037] (1) The obtained granules are fed into screw extruder 1 for plasticization and extrusion to obtain intermediate material;

[0038] (2) The calender is combined with the first coating device 2 and the second coating device 3. The intermediate material enters between the calender rolls 4 of the calender and is plasticized and calendered into a sheet-like intermediate layer. Carbon black is pre-coated on the surface of the graphite film to enhance its roughness. Then, the graphite film is laminated onto the surface of the sheet-like intermediate layer by the calender rolls 4 and the coating devices on both sides. Finally, the composite calendering yields a multilayer composite high thermal conductivity film 00. The specific process parameters are as follows:

[0039] The screw extruder operates at an extrusion temperature of 180±30℃ and a pressure of 10±5MPa, while the calender roll temperature is 80-180℃ and the pressure is 2-10MPa. These design parameters ensure a dense structure in the resulting film material.

[0040] The graphite film is either artificial graphite or high-density natural graphite, with a thickness of 0.01-0.05 mm and a planar thermal conductivity between 300-1900 W / mK. Depending on customer requirements, a 2µm particle size carbon black coating can be applied to the graphite surface between the graphite film and the sheet-like interlayer to increase roughness and enhance interfacial adhesion. Alternatively, a rough surface can be directly ablated using laser scanning ablation. When the extruded semi-fluid interlayer is subjected to composite calendering, the serrated rough surface significantly improves interfacial adhesion.

[0041] The thickness of the multilayer composite high thermal conductivity film prepared by the above process is 0.03-3mm, and the planar thermal conductivity can be selected between 30-900218 W / (m·K). After edge wrapping, the precipitation rate is less than 3.5% after 500 hours of double 85 test.

[0042] The expanded graphite used in the aforementioned intermediate layer is ultra-low density graphite particles formed by the expansion of natural graphite. It possesses a high surface area and porous structure, enabling it to adsorb and store phase change materials. The graphite film, on the other hand, is a high-density graphite sheet, formed by calendering expanded graphite particles. Current impregnation methods cannot increase the enthalpy of phase change materials because the expanded graphite must first be calendered into a film. The film itself requires a certain density to achieve toughness and strength. At this density, the maximum phase change material capacity is approximately 1:1. When a certain thickness is reached, it can only be made into sheets and cannot be rolled, thus limiting the efficiency of subsequent impregnation processing.

[0043] The following are two specific examples:

[0044] Example 1:

[0045] Linear alkanes were selected from fatty acids. 75 kg of phase change fatty acids, 22 kg of expanded graphite, 3 kg of polyolefin, and 22 kg of artificial graphite were weighed. First, the phase change fatty acids, expanded graphite, and polyolefin were mixed and melt-blended at 180℃ for 30 minutes; then crushed into granules with a particle size of 0.5-3 mm; using a screw extruder and calender, with extrusion temperature set at 180℃, pressure at 10 MPa, and calender roll temperature at 90℃, a double-layer calender was used to produce a film with a thickness of 0.015 mm; the planar thermal conductivity was tested to be 647 W / (m·K), and after die-cutting and edge binding, the exudation rate was less than 3.5% after 500 hours of double 85 testing.

[0046] Example 2: The straight-chain alkane used was n-docosahexanes. 52 kg of n-docosahexanes, 48 ​​kg of low-density expanded graphite, 3 kg of binder, and 25 kg of artificial graphite were weighed. First, the n-docosahexanes, low-density expanded graphite, and binder were mixed and melt-blended at 180°C for 30 minutes; then crushed into particles with a particle size of 0.5-3 mm. A screw extruder and calender were used, with the extrusion temperature set to 180°C, pressure to 10 MPa, and calender roll temperature to 90°C. An artificial graphite film was output from the coating device and double-calendered to a thickness of 0.03 mm. The planar thermal conductivity was measured to be 218 W / (m·K), and after die-cutting and edge binding, the precipitation rate was less than 3.5% after 500 hours of double 85 testing.

[0047] Compared with existing impregnation and blending die casting methods, the multilayer composite high thermal conductivity film prepared by this invention has significant advantages in terms of thickness range, production efficiency, precipitation rate, and planar thermal conductivity.

[0048] The multilayer composite high thermal conductivity film prepared using this invention is compared with existing thermal storage materials in the following tests:

[0049] 1. Test Objective

[0050] At the same power consumption (approximately 1.83W), the surface temperature of the multilayer composite high thermal conductivity film and existing thermal storage materials rose to 43°C. The longer the time, the better the thermal storage performance.

[0051] 2. Preparation of thermal storage materials

[0052] The multilayer composite high thermal conductivity film sample prepared using this invention has the following composition by mass ratio: 52% n-docosahexanes, 20% low-density expanded graphite, 25% artificial graphite, and 3% binder.

[0053] The existing thermal storage material has the following composition by mass: 52% n-dodecane and 48% low-density expanded graphite.

[0054] The existing dimensions of the sample and thermal storage material are: 100*50*0.3MM.

[0055] 3. Test fixture stacking: thermal insulation material—heating film—aluminum substrate—heat storage material (coated with adhesive and film)

[0056] 4. Test conditions

[0057] Ambient temperature: 25.5±0.5℃ (controlled by constant temperature chamber).

[0058] Power consumption: 3V DC power supply, total power consumption is about 1.8W.

[0059] Temperature measuring point: Center of the surface of the thermal storage material

[0060] The detailed comparison of experimental data is shown in the table below:

[0061]

[0062] Test results: Based on the average overheating time at 43℃ / 48℃, the multilayer composite high thermal conductivity film outperforms existing thermal storage materials in terms of thermal storage performance under both temperature conditions.

[0063] 43℃ Test: The average overheating time of the multi-layer composite high thermal conductivity film was 6.1 minutes, significantly higher than the 5.0 minutes of existing thermal storage materials, representing a 22% improvement in performance.

[0064] 48℃ test: The average overheating time of the multi-layer composite high thermal conductivity film is 7.0 minutes, which is better than the 6.2 minutes of the existing thermal storage materials, and the effect is improved by 12.9%.

[0065] Compared with the existing impregnation method and blending die casting method for preparing thermal storage materials, the planar thermal conductivity of the process of this invention is compared as shown in the table below. The units of the planar thermal conductivity in the table are W / (m·K).

[0066]

[0067] It is evident that the planar thermal conductivity of the multilayer composite high thermal conductivity film prepared by the present invention is far superior to that of the thermal conductivity of the heat storage materials prepared by the existing impregnation method and blending die casting method.

[0068] In summary, this invention can overcome the thickness limitations of traditional methods and adapt to diverse applications; improve production efficiency: the continuous extrusion and calendering process shortens the production cycle; reduce precipitation: the synergistic effect of polyolefin and granular material, plus the densifying and suppressing effect of artificial graphite, inhibits the migration of phase change materials; and improve planar thermal conductivity: the multilayer composite of expanded graphite and artificial graphite film enhances the thermal conductivity path.

[0069] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a multilayer composite high thermal conductivity phase change thermal storage film, characterized in that: The multilayer composite high thermal conductivity film includes an intermediate layer and a graphite film on its surface, wherein the intermediate layer comprises the following raw material components: Organic phase change substrate: 50-80 parts; Expanded graphite: 17-48 parts; Adhesive: 1-3 parts; The above raw material components are melted, blended, and crushed to obtain granules; the granules used to prepare the intermediate layer are then processed into an intermediate layer using a film-forming process, and the intermediate layer is then calendered with a graphite film to obtain a multilayer composite high thermal conductivity film.

2. The method for preparing a multilayer composite high thermal conductivity phase change thermal storage film according to claim 1, characterized in that: The organic phase change substrate is one or more of straight-chain alkanes, fatty acids, and polyethylene glycol.

3. The method for preparing a multilayer composite high thermal conductivity phase change thermal storage film according to claim 2, characterized in that: The melting temperature of the organic phase change substrate, expanded graphite and binder is controlled at 180℃±30℃, and they are blended for 30±10 minutes; then crushed into particles with a particle size of 0.5-1mm.

4. The method for preparing a multilayer composite high thermal conductivity phase change thermal storage film according to claim 1, characterized in that: The film-forming process is completed using a screw extruder, a calender, and a coating device, and includes the following steps: (1) The obtained granules are fed into a screw extruder for plasticization and extrusion to obtain intermediate material; (2) The calender and the coating device are combined. The intermediate material enters the calender and is plasticized and calendered into a sheet intermediate layer. The calender and the coating device are combined to coat the graphite film on the surface of the sheet intermediate layer. Finally, the composite calendering is used to obtain a multi-layer composite high thermal conductivity film.

5. The method for preparing a multilayer composite high thermal conductivity phase change thermal storage film according to claim 4, characterized in that: In step (2), the extrusion temperature of the screw extruder is 180±30℃ and the pressure is 10±5MPa, and the calender roll temperature is 80-180℃ and the pressure is 2-10MPa.

6. The method for preparing a multilayer composite high thermal conductivity phase change thermal storage film according to claim 4, characterized in that: The graphite film is an artificial graphite film or a high-density natural graphite film, and the thickness of the graphite film is 0.01-0.05mm, with a planar thermal conductivity between 300-1900w / mk.

7. The method for preparing a multilayer composite high thermal conductivity phase change thermal storage film according to claim 4, characterized in that: The graphite film covers one or both sides of the sheet-like intermediate layer, and a nano-thermal conductive filler is provided between the graphite film and the sheet-like intermediate layer.

8. A method for preparing a multilayer composite high thermal conductivity phase change thermal storage film according to any one of claims 1-7, characterized in that: The thickness of the multilayer composite high thermal conductivity film is 0.03-3mm.

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