Preparation method and application of high-thermal-conductivity PET water-blocking tape

Abstract

The invention relates to the technical field of polymer composite materials, in particular to a preparation method and application of a high-thermal-conductivity PET water-blocking tape. The invention aims to solve the technical problems of high raw material cost and difficulty in giving consideration to both thermal conductivity and flexibility. Surface-modified boron nitride nanosheets (BNNS) and silicon carbide whiskers (SiCw) are mixed according to a mass ratio to form a three-dimensional heat-conducting network, then uniformly dispersed heat-conducting filler slurry is prepared by adopting an ultrasonic-centrifugal gradient dispersion technology, and a composite film with a gradient dispersion structure is formed by adopting a three-layer co-extrusion technology, so that the problem of nanofiller agglomeration can be solved, and the heat-conducting property of the composite film is improved. And finally, preparing a vein-shaped micro-channel network on the surface of the membrane by using a CO2 laser micro-engraving technology, so that the heat dissipation uniformity is enhanced, and the water resistance of the micro-channel structure is not sacrificed. The PET water-blocking tape provided by the invention solves the contradiction between heat conduction and mechanical properties of a traditional blending process, can improve the heat conduction performance, reduce the water vapor permeation amount and improve the elongation at break, and has a wide application prospect in the fields of cables, optical cables and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a method for preparing and applying a high thermal conductivity PET water-blocking tape, which is particularly suitable for water-blocking protection in fields such as power cables and communication optical cables. Background Technology

[0002] PET (polyethylene terephthalate) water-blocking tape is an important waterproof and moisture-proof material in cables and optical fibers. It is mainly used to prevent moisture from penetrating the cable's interior, avoiding problems such as decreased insulation performance and reduced signal transmission quality caused by moisture. With the development of power and communication technologies, the performance requirements for water-blocking tape are becoming increasingly stringent.

[0003] Traditional PET water barrier tapes have the following main technical problems: 1. Insufficient thermal conductivity: The thermal conductivity of pure PET material is only about 0.19 W / (m·K). Heat conduction mainly relies on phonons, and the diffusion rate is limited. The heat generated during cable operation cannot be dissipated in time, leading to local temperature rise, affecting insulation performance, and limiting the cable's current carrying capacity and operating efficiency.

[0004] 2. Decreased flexibility after adding thermally conductive fillers: To improve thermal conductivity, rigid ceramic fillers such as alumina and boron nitride are usually added. When the filler content exceeds 50wt%, it will disrupt the continuity of the polymer chain, causing the material to become brittle, reduce tensile strength, decrease elongation at break, and easily lead to cracking and delamination in practical applications.

[0005] 3. Nanofiller agglomeration problem: Nanofillers have high specific surface area and surface energy, and are prone to agglomeration under the action of van der Waals forces. This results in uneven distribution of the filler in the matrix, making it impossible to form an effective heat conduction network. At the same time, it increases the water vapor permeability of the material and reduces its water-blocking performance.

[0006] 4. High cost: High-performance thermally conductive fillers are expensive, and the need for special dispersion equipment and processes leads to high production costs.

[0007] Existing technologies have attempted to improve the performance of PET water-blocking tapes, such as surface functionalization and hybrid particle technology, but these methods struggle to simultaneously address multiple aspects, including thermal conductivity, flexibility, water resistance, and cost. Therefore, there is an urgent need to develop a new technological solution that achieves a comprehensive performance profile of high thermal conductivity, high flexibility, low water vapor transmission, and low cost. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing high thermal conductivity PET water-blocking tape. Through innovative filler system design, dispersion technology, and surface microstructure treatment, a balance between thermal conductivity and flexibility is achieved while maintaining excellent water-blocking performance. The technical solution of this invention is as follows: A method for preparing a high thermal conductivity PET water-blocking tape includes the following steps: S1: Preparation and Dispersion of Thermally Conductive Fillers Boron nitride nanosheets (BNNS) and silicon carbide whiskers (SiCw) were added to an ethanol solution containing silane coupling agent KH550, respectively, and stirred at 100°C for 2.5–3.5 hours. After filtration, washing, and drying, surface-modified boron nitride nanosheets and silicon carbide whiskers were obtained.

[0009] Boron nitride nanosheets provide lateral heat conduction pathways, while silicon carbide whiskers act as longitudinal heat conduction bridges, forming a three-dimensional heat conduction network in synergy. The whisker structure of silicon carbide whiskers can penetrate the gaps between the stacked boron nitride nanosheets, reducing phonon scattering; the sheet-like shielding effect of boron nitride nanosheets can extend the diffusion path of water molecules, while the stress transfer effect of silicon carbide whiskers can inhibit microcrack propagation and improve elongation at break; the sheet-like shape of boron nitride nanosheets and the wire-like shape of silicon carbide whiskers can achieve size complementarity, reduce filler agglomeration, and reduce ultrasonic dispersion time.

[0010] S2: Ultrasonic-centrifugal gradient dispersion Surface-modified boron nitride nanosheets and silicon carbide whiskers were mixed in a specific mass ratio, added to ethanol, and a dispersant was added simultaneously. The mixture was then sonicated, and the dispersion was transferred to a centrifuge tube. A sucrose density gradient medium was added, and the mixture was centrifuged. The well-dispersed intermediate layer of the filler slurry was collected.

[0011] Furthermore, polyvinylpyrrolidone (PVP) was chosen as the dispersant.

[0012] Furthermore, the ultrasonic treatment employs a probe-type ultrasonic treatment with a power density of 2W / mL to 3W / mL, a frequency of 20kHz to 40kHz, and a treatment time of 30 to 60 minutes, during which the temperature is controlled to not exceed 40℃ using a water bath.

[0013] Furthermore, the centrifugation speed is 20,000 rpm to 30,000 rpm, and the centrifugation time is 30 to 40 minutes.

[0014] Furthermore, the sucrose density is 1.5 g / cm³ to 2.5 g / cm³.

[0015] S3: Preparation of composite membranes PET resin was vacuum dried at 120℃ for 4 hours. A three-layer co-extrusion process was adopted, and the extrusion speed of the extruder was adjusted. The three layers of PET with different compositions and thermally conductive fillers were transported from independent channels, merged and pressurized at 10 MPa to obtain a composite film. After leaving the co-extrusion die, the film immediately entered a three-roll calender for cooling and molding.

[0016] Furthermore, the relevant parameter settings for the three layers of PET with different compositions and the thermally conductive filler are as follows: Top layer: pure PET, extrusion temperature 260℃~270℃, thickness percentage 15%~25%.

[0017] Middle layer: PET is mixed with 22wt% to 28wt% thermally conductive filler, extrusion temperature is 265℃ to 275℃, and thickness accounts for 50% to 70%.

[0018] Lower layer: PET is mixed with 6wt% to 10wt% thermally conductive filler, extruded at 260℃ to 270℃, and has a thickness of 15% to 25%.

[0019] Furthermore, with an extrusion speed of 8m / min to 15m / min and a cooling roller temperature of 45℃ to 55℃, a composite film with a thickness of 0.25mm to 0.4mm is obtained.

[0020] S4: Surface microstructure treatment A biomimetic leaf vein-like microchannel network was prepared on the surface of a composite membrane using CO2 laser engraving technology. The leaf vein-like pattern was designed, and after laser scanning, the surface residue was removed with compressed air. This microchannel structure enhances the lateral conduction and dissipation of heat on the one hand, and improves the water-blocking performance through the capillary effect on the other.

[0021] Furthermore, the laser power is set to 25W to 40W, the scanning speed to 80mm / s to 150mm / s, and the pulse frequency to 15kHz to 20kHz.

[0022] Furthermore, a leaf vein pattern was designed, with the main channel having a width of 150μm to 250μm and a depth of 50μm to 80μm; the branch channels having a width of 50μm to 80μm and a depth of 25μm to 40μm; and the channel spacing being 300μm.

[0023] The beneficial effects of this invention are: This invention uses surface-modified boron nitride nanosheets (BNNS) and silicon carbide whiskers (SiCw) as fillers. Compared with the traditional method that uses graphene as the main component, this invention can reduce the cost of raw materials.

[0024] In this invention, a gradient dispersion structure is formed through a three-layer co-extrusion process, which can solve the problem of nanofiller agglomeration. The three-dimensional thermally conductive network formed by boron nitride nanosheets and silicon carbide whiskers can improve thermal conductivity, reduce water molecule permeability, and increase elongation at break.

[0025] This invention utilizes CO2 laser micro-engraving technology to prepare a leaf vein-like microchannel network on the membrane surface, which enhances the uniformity of lateral heat dissipation and does not sacrifice water resistance. It has broad application prospects in the fields of cables and optical cables. Attached Figure Description

[0026] Figure 1 This is a process flow diagram for preparing a high thermal conductivity PET water-blocking tape according to the present invention.

[0027] Figure 2 A comparison of the thermal conductivity of the high thermal conductivity PET water-blocking tape of the present invention prepared under different conditions.

[0028] Figure 3 A comparison chart showing the water vapor transmission rate of a high thermal conductivity PET water-blocking tape prepared under different conditions according to the present invention.

[0029] Figure 4 Comparison of the elongation at break of the high thermal conductivity PET water-blocking tape prepared under different conditions according to the present invention. Detailed Implementation

[0030] The following embodiments further explain and illustrate the technical solution of the present invention. It is particularly noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention. (See attached...) Figure 1 The diagram shows a manufacturing process for a high thermal conductivity PET water-blocking tape. The detailed manufacturing steps are as follows: 1. Preparation of thermally conductive fillers Boron nitride nanosheets (BNNS) and silicon carbide whiskers (SiCw) were added to an ethanol solution containing silane coupling agent KH550, respectively, and stirred at 100°C for 2.5–3.5 hours. After filtration, washing, and drying, surface-modified boron nitride nanosheets and silicon carbide whiskers were obtained.

[0031] 2. Ultrasonic-centrifugal gradient dispersion Surface-modified boron nitride nanosheets and silicon carbide whiskers were mixed in a specific mass ratio, added to ethanol, and a dispersant was added simultaneously. The mixture was then sonicated, and the dispersion was transferred to a centrifuge tube. A sucrose density gradient medium was added, and the mixture was centrifuged. The well-dispersed intermediate layer of the filler slurry was collected.

[0032] The dispersant chosen is polyvinylpyrrolidone (PVP).

[0033] The proportion of dispersant is 0.5% to 5% of the filler mass.

[0034] The ultrasonic treatment was performed using a probe-type ultrasonic treatment with a power density of 2W / mL to 3W / mL, a frequency of 20kHz to 40kHz, and a treatment time of 30 to 60 minutes. During the treatment, the temperature was controlled to not exceed 40℃ using a water bath.

[0035] Centrifuge at 20,000 rpm to 30,000 rpm for 30 to 40 minutes.

[0036] Sucrose density is 1.5 g / cm³ to 2.5 g / cm³.

[0037] 3. Preparation of composite membranes PET resin was vacuum dried at 120℃ for 4 hours. A three-layer co-extrusion process was adopted, and the extrusion speed of the extruder was adjusted. The three layers of PET with different compositions and thermally conductive fillers were transported from independent channels, merged and pressurized at 10 MPa to obtain a composite film. After leaving the co-extrusion die, the film immediately entered a three-roll calender for cooling and molding.

[0038] The relevant parameter settings for three layers of PET with different compositions and thermally conductive fillers are as follows: Top layer: pure PET, extrusion temperature 260℃~270℃, thickness percentage 15%~25%.

[0039] Middle layer: PET is mixed with 22wt% to 28wt% thermally conductive filler, extrusion temperature is 265℃ to 275℃, and thickness accounts for 50% to 70%.

[0040] Lower layer: PET is mixed with 6wt% to 10wt% thermally conductive filler, extruded at 260℃ to 270℃, and has a thickness of 15% to 25%.

[0041] Extrusion speed of 8m / min to 15m / min and cooling roller temperature of 45℃ to 55℃ are used to produce composite films with a thickness of 0.25mm to 0.4mm.

[0042] 4. Surface microstructure treatment A biomimetic leaf vein-like microchannel network was prepared on the surface of a composite membrane using CO2 laser engraving technology. The leaf vein-like pattern was designed, and after laser scanning, the surface residue was removed with compressed air. This microchannel structure enhances the lateral conduction and dissipation of heat on the one hand, and improves the water-blocking performance through the capillary effect on the other.

[0043] Set the laser power to 25W-40W, the scanning speed to 80mm / s-150mm / s, and the pulse frequency to 15kHz-20kHz.

[0044] The design features a leaf vein pattern with a main channel width of 150μm–250μm and a depth of 50μm–80μm; branch channels with a width of 50μm–80μm and a depth of 25μm–40μm; and a channel spacing of 300μm.

[0045] After the laser scan is completed, compressed air is used to remove any residue from the surface.

[0046] Example 1 A method for preparing a high thermal conductivity PET water-blocking tape is as follows: S1: Surface modification of thermally conductive fillers: Take 10g of boron nitride nanosheets and 40g of silicon carbide whiskers, add them to an ethanol solution containing 2wt% silane coupling agent KH550, stir and react at 100℃ for 2.5 hours, filter, wash and dry to obtain surface-modified boron nitride nanosheets and silicon carbide whiskers.

[0047] S2: Ultrasonic-Centrifugal Gradient Dispersion: Surface-modified boron nitride nanosheets and silicon carbide whiskers were mixed at a mass ratio of 1:4 and added to 500 mL of ethanol, along with 2.5 g of polyvinylpyrrolidone (PVP) as a dispersant. Probe-type ultrasonic treatment was performed at a power density of 2 W / mL and a frequency of 20 kHz for 60 minutes, with the temperature controlled to not exceed 40°C using a water bath. After ultrasonic treatment, the dispersion was transferred to centrifuge tubes, and a sucrose density gradient medium (density 1.5 g / cm³) was added. The mixture was centrifuged at 20,000 rpm for 30 minutes. The well-dispersed intermediate layer of the slurry was collected.

[0048] S3: Preparation of composite film: PET resin is vacuum dried at 120℃ for 4 hours. A three-layer co-extrusion process is adopted. The extrusion speed of the extruder is adjusted, and the three layers of PET with different compositions and thermally conductive fillers are transported from independent channels, merged and pressurized at 10 MPa to obtain a composite film. After leaving the co-extrusion die, it immediately enters a three-roll calender for cooling and molding.

[0049] The relevant parameter settings for three layers of PET with different compositions and thermally conductive fillers are as follows: Top layer: pure PET, extrusion temperature 265℃, thickness percentage 20%.

[0050] Middle layer: PET mixed with 25wt% thermally conductive filler, extrusion temperature 270℃, thickness accounting for 60%.

[0051] Bottom layer: PET mixed with 8wt% thermally conductive filler, extrusion temperature 265℃, thickness percentage 20%.

[0052] A composite film with a thickness of 0.3 mm was obtained by extruding at a speed of 10 m / min and cooling roller temperature of 50 ℃.

[0053] S4: Laser micro-engraving: A CO2 laser engraving machine is used, with the laser power set to 30W, scanning speed to 100mm / s, and pulse frequency to 10kHz.

[0054] The design features a leaf vein pattern with a main channel width of 200μm and a depth of 60μm; branch channels with a width of 60μm and a depth of 30μm; and a channel spacing of 300μm.

[0055] After the laser scan is completed, compressed air is used to remove any residue from the surface.

[0056] Example 2 A method for preparing a high thermal conductivity PET water-blocking tape is as follows: The preparation method of the high thermal conductivity PET water-blocking tape in Example 1 is different in that... In step S1 of the preparation process, 15g of boron nitride nanosheets and 45g of silicon carbide whiskers were taken and surface-treated with silane coupling agent KH550 at a dosage of 2.5wt% at a temperature of 105℃ for 3 hours.

[0057] In step S2 of the preparation process, boron nitride nanosheets and silicon carbide whiskers were mixed at a mass ratio of 1:3, and 3.0 g of polyvinylpyrrolidone (PVP) was added as a dispersant. The mixture was ultrasonically treated at a power density of 2.5 W / mL and a frequency of 30 kHz for 45 minutes. The mixture was then centrifuged at 25,000 rpm for 35 minutes, and a sucrose density gradient medium of 2.0 g / cm³ was added.

[0058] In step S3 of the preparation process, Top layer: pure PET, extrusion temperature 260℃, thickness percentage 15%.

[0059] Middle layer: PET mixed with 28wt% thermally conductive filler, extruded at 275℃, with a thickness of 70%.

[0060] Bottom layer: PET with 6wt% thermally conductive filler, extrusion temperature 260℃, thickness percentage 15%.

[0061] A composite film with a thickness of 0.25 mm was obtained by extruding at a speed of 15 m / min and cooling roller temperature of 45 ℃.

[0062] In step S4 of the fabrication process, the laser power for laser micro-engraving is 25W, the scanning speed is 150mm / s, and the pulse frequency is 15kHz. The main channel width is 150μm and the depth is 50μm; the branch channel width is 50μm and the depth is 25μm.

[0063] Example 3 A method for preparing a high thermal conductivity PET water-blocking tape is as follows: The preparation method of the high thermal conductivity PET water-blocking tape in Example 1 is different in that... In step S1 of the preparation process, 20g of boron nitride nanosheets and 40g of silicon carbide whiskers were taken and surface treated with silane coupling agent KH550 at a dosage of 3wt% at a temperature of 110℃ for 3.5 hours.

[0064] In step S2 of the preparation process, boron nitride nanosheets and silicon carbide whiskers were mixed at a mass ratio of 1:2, and 3.5 g of polyvinylpyrrolidone (PVP) was added as a dispersant. The mixture was ultrasonically treated at a power density of 3 W / mL and a frequency of 40 kHz for 30 minutes. The mixture was then centrifuged at 30,000 rpm for 40 minutes, and a sucrose density gradient medium of 2.5 g / cm³ was added.

[0065] In step S3 of the preparation process, Top layer: pure PET, extrusion temperature 270℃, thickness percentage 25%.

[0066] Middle layer: 22wt% thermally conductive filler, extrusion temperature 265℃, thickness accounts for 50%.

[0067] Bottom layer: 10wt% thermally conductive filler, extrusion temperature 270℃, thickness percentage 25%.

[0068] An extrusion speed of 8 m / min yields a composite film with a thickness of 0.4 mm.

[0069] In step S4 of the fabrication process, the laser power for laser micro-engraving is 40W, the scanning speed is 80mm / s, and the pulse frequency is 20kHz. The main channel width is 250μm and the depth is 80μm; the branch channel width is 80μm and the depth is 40μm.

[0070] Comparative Example 1 The preparation steps are the same as in Example 1, except for step S3: Without using gradient decomposition technology, PET is mixed with 20wt% thermally conductive filler, with the filler content uniformly distributed, and extruded at an extrusion temperature of 265℃ for single-layer extrusion; the remaining steps are the same.

[0071] Comparative Example 2 The preparation steps are the same as in Example 1, except for step S4: After the three-layer co-extrusion process is completed, no laser micro-engraving is performed; the remaining steps are the same.

[0072] Comparative Example 3 The preparation steps are the same as in Example 1, except that in S1: Boron nitride nanosheets were used as the thermally conductive filler, with a filling amount of 50g, and the other steps were the same.

[0073] The high thermal conductivity PET water-blocking tapes prepared in Examples 1-3 and Comparative Examples 1-3 were compared in terms of their comprehensive performance. For thermal conductivity, the thermal conductivity coefficient was tested using the laser flash method for cross-verification, and the measurement was performed according to standard ISO 22007-4-2024, "Determination of thermal conductivity and thermal diffusivity of plastics". For water-blocking performance, the water vapor transmission rate was measured according to standard GB / T 1037-2021, "Determination of water vapor transmission rate of plastic films and sheets - cup weight gain and weight loss method". For mechanical properties, the elongation at break was measured according to standards ISO 527-3:2018, "Analysis of test methods for tensile properties of plastic films and sheets", and ISO 527-1:2019, "Determination of tensile properties of plastics". Specific test comparison results are shown in Table 1 and Appendix. Figure 2-4 As shown: Table 1. Comparison of overall performance between Examples 1-3 and Comparative Examples 1-3

[0074] The comparison results show that in Comparative Example 1, no gradient decomposition technology was used. Gradient distribution can maintain the surface density of the filler. Although the thermal conductivity is acceptable without a gradient structure, the mechanical properties and water-blocking properties are significantly reduced. In Comparative Example 2, no laser micro-engraving was performed because laser engraving forms a biomimetic leaf vein-like microchannel network on the surface, which can significantly improve the heat diffusion capacity. Therefore, the thermal conductivity and water-blocking properties are significantly affected in the experimental results. In Comparative Example 3, only boron nitride nanosheets were used as thermally conductive fillers without the use of silicon carbide whiskers. The experimental results show that the thermal conductivity, water-blocking properties, and mechanical properties are significantly affected. This is because silicon carbide whiskers act as longitudinal bridges, forming a three-dimensional thermally conductive network with boron nitride nanosheets, which can directionally optimize the thermal conductivity. Furthermore, silicon carbide whiskers penetrate the gaps between the stacked boron nitride nanosheets, which can reduce phonon dispersion. The fiber reinforcement effect of silicon carbide whiskers compensates for the decrease in mechanical properties caused by the addition of boron nitride nanosheets.

Claims

1. A method for preparing a high thermal conductivity PET water-blocking tape, characterized in that, After surface modification of boron nitride nanosheets and silicon carbide whiskers, they were mixed in a mass ratio and then a uniformly dispersed thermally conductive filler slurry was prepared using ultrasonic-centrifugal gradient dispersion technology. A composite film with a gradient dispersion structure was formed through a three-layer co-extrusion process. Finally, a leaf vein-like microchannel network was prepared on the film surface using CO2 laser micro-engraving technology.

2. The method for preparing a high thermal conductivity PET water-blocking tape according to claim 1, characterized in that, Includes the following steps: S1: Boron nitride nanosheets and silicon carbide whiskers were added to an ethanol solution containing silane coupling agent KH550, and stirred at 100°C for 2.5 to 3.5 hours. After filtration, washing and drying, surface-modified boron nitride nanosheets and silicon carbide whiskers were obtained. S2: Surface-modified boron nitride nanosheets and silicon carbide whiskers are mixed in a mass ratio of 1:2 to 1:4, added to ethanol, and polyvinylpyrrolidone dispersant is added at the same time; the mixture is ultrasonically treated, and then the dispersion is transferred to a centrifuge tube, sucrose density gradient medium is added and centrifuged, and the well-dispersed filler slurry in the middle layer is collected. S3: Vacuum dry PET resin at 120℃ for 4 hours, adopt a three-layer co-extrusion process, adjust the extruder extrusion speed, and transport three layers of PET with different compositions and thermally conductive fillers from independent channels. They are then combined and pressurized at 10 MPa to obtain a composite film. After leaving the co-extrusion die, the film immediately enters a three-roll calender for cooling and molding. S4: A biomimetic leaf vein-like microchannel network is prepared on the surface of the composite membrane using CO2 laser engraving technology. Leaf vein-like patterns are designed. After laser scanning, surface residues are removed with compressed air.

3. The method for preparing a high thermal conductivity PET water-blocking tape according to claim 2, characterized in that, The ultrasonic treatment described in S2 uses a probe-type ultrasonic treatment, with a power density of 2W / mL to 3W / mL, a frequency of 20kHz to 40kHz, and a treatment time of 30 to 60 minutes, during which the temperature is controlled to not exceed 40℃ using a water bath.

4. The method for preparing a high thermal conductivity PET water-blocking tape according to claim 2, characterized in that, The centrifugation described in S2 is set with a centrifugation speed of 20,000 rpm to 30,000 rpm and a centrifugation time of 30 to 40 minutes.

5. The method for preparing a high thermal conductivity PET water-blocking tape according to claim 2, characterized in that, The three-layer PET and thermally conductive filler with different compositions described in S3 are configured with the following parameters: upper layer: pure PET, extrusion temperature 260℃~270℃, thickness percentage 15%~25%; middle layer: PET mixed with 22wt%~28wt% thermally conductive filler, extrusion temperature 265℃~275℃, thickness percentage 50%~70%; lower layer: PET mixed with 6wt%~10wt% thermally conductive filler, extrusion temperature 260℃~270℃, thickness percentage 15%~25%.

6. The method for preparing a high thermal conductivity PET water-blocking tape according to claim 2, characterized in that, The three-layer co-extrusion process described in S3, with an extrusion speed of 8m / min to 15m / min and a cooling roller temperature of 45℃ to 55℃, produces a composite film with a thickness of 0.25mm to 0.4mm.

7. The method for preparing a high thermal conductivity PET water-blocking tape according to claim 2, characterized in that, The CO2 laser engraving technology described in S4 is configured with a laser power of 25W to 40W, a scanning speed of 80mm / s to 150mm / s, and a pulse frequency of 15kHz to 20kHz.

8. The method for preparing a high thermal conductivity PET water-blocking tape according to claim 2, characterized in that, The leaf vein pattern described in S4 has a main channel width of 150μm to 250μm and a depth of 50μm to 80μm; branch channels have a width of 50μm to 80μm and a depth of 25μm to 40μm; and a channel spacing of 300μm.

9. A high thermal conductivity PET water-blocking tape prepared by the method according to any one of claims 1-8, characterized in that, The parameters of the high thermal conductivity PET water-blocking tape are as follows: thermal conductivity of 3.2W / (m·K)~3.6W / (m·K), water vapor transmission rate <0.04g / (m²·24h), elongation at break ≥150%, and thickness of 0.25mm~0.4mm.

10. A high thermal conductivity PET water-blocking tape according to claim 9, characterized in that, The high thermal conductivity PET water-blocking tape is used as a water-blocking material in power cables, communication optical cables, submarine cables, or special cables.

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