A method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape

Abstract

A method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape is disclosed, which relates to a method for preparing a rubber buffer layer composite material. The purpose of this invention is to solve the problems of easy failure of water-blocking performance, unstable interfacial resistance, and deterioration of electrical performance after long-term thermal aging in existing high-voltage cable buffer layers. This invention breaks through technical bottlenecks by utilizing the intrinsic water-blocking properties of butyl rubber, precisely controlling its high conductivity, and innovating multi-level structures. A wide-temperature-range semiconductor butyl buffer layer composite tape with butyl rubber as the matrix and multiple fillers such as carbon black, graphene, and carbon nanotubes as synergistic reinforcement is designed and prepared. Testing shows that it can achieve long-term water-blocking protection without relying on water-blocking powder, maintains low volume resistivity throughout the wide temperature range of -40℃ to 100℃, and shows no significant attenuation of core performance after 7×24h continuous thermal aging. It also possesses a certain degree of viscosity, making it suitable for the full-condition operation requirements of high-voltage cable buffer layers.

Description

Technical Field

[0001] This invention relates to a method for preparing a rubber buffer layer composite material. Background Technology

[0002] Cross-linked polyethylene (XLPE) insulated cables are widely used in power grid transmission and distribution systems due to their excellent high-temperature resistance, stable electrical insulation properties, and good chemical and aging resistance. In my country, high-voltage cables commonly use corrugated aluminum sheaths because of their low cost, good conductivity, high flexibility, and ease of processing. However, during cable laying and bending, the troughs of the corrugated aluminum sheath can easily damage the insulation shielding layer. Therefore, a buffer layer is usually placed between the insulation shielding layer and the aluminum sheath to improve electrical contact, provide mechanical buffering, and achieve water-blocking function, thereby reducing the risk of insulation degradation and improving the safety and stability of cable operation. However, the existing mainstream water-blocking powder-type buffer layer system has inherent defects such as a sharp increase in resistivity after water absorption, interfacial contact failure, and poor long-term service stability, failing to achieve long-term synergy between water-blocking performance and semi-conductive properties from the material's inherent nature.

[0003] Domestic and international scholars have conducted extensive research on the ablation failure of the buffer layer in high-voltage cross-linked polyethylene cables. They have found that increased interfacial resistance of the buffer layer and insufficient tightness between the corrugated aluminum sheath and the buffer layer are important causes of buffer layer failure. The mainstream prevention method involves combining non-woven fabric, carbon black, other conductive fillers, and water-blocking powder, using the added water-blocking powder to provide water resistance to the buffer layer. Under normal conditions, the cable can operate normally. However, with prolonged operation, increased voltage levels, and external moisture erosion, the water-blocking powder in the buffer layer becomes saturated, leading to an increase in resistivity. The precipitated powder reacts with carbon dioxide and the aluminum sheath to form aluminum oxide powder, causing a sharp increase in resistivity. This disrupts the equipotential with the insulation shield, resulting in discharge ablation. Preliminary explorations have been made into ablation repair technology. The method involves filling the buffer layer and air gap with a conductive slurry. After the repair liquid is injected into the cable, its fluidity allows it to wet the buffer layer and penetrate the outer shield surface, forming a good conductive path between the insulation shield and the aluminum sheath, thereby mitigating ablation. However, this method still has some problems. For example, the slurry may react adversely with the original buffer layer or cable body components. During long-term operation, the stability is insufficient due to the effects of thermal expansion and contraction, and the slurry is prone to cracking and falling off. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of easy failure of water-blocking performance, unstable interface resistance, and deterioration of electrical performance after long-term thermal aging of existing high-voltage cable buffer layers, and to provide a method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape.

[0005] To overcome the shortcomings of existing technologies, this invention focuses on utilizing the intrinsic water-blocking properties of butyl rubber, precisely controlling its high conductivity, and innovating its multi-level structure to break through technical bottlenecks. It designs and prepares a wide-temperature-range semiconductor butyl buffer layer composite tape with butyl rubber (IIR) as the matrix and various fillers such as carbon black, graphene, and carbon nanotubes for synergistic reinforcement.

[0006] A method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape is specifically carried out according to the following steps:

[0007] I. Preparation of Semiconducting Colloidal Materials:

[0008] ① Add butyl rubber to a mixer for plasticizing to obtain plasticized butyl rubber;

[0009] ② Mix carbon black A, carbon black B, graphene and carbon nanotubes evenly to obtain functional filler; add functional filler to plasticized butyl rubber and mix to obtain functional filler modified butyl rubber.

[0010] ③ Add stearic acid, zinc oxide, antioxidant and paraffin to functional filler modified butyl rubber, and continue to mix to obtain additive modified butyl rubber;

[0011] ④ Add polyisobutylene to the additive-modified butyl rubber and continue to mix to obtain polyisobutylene-modified butyl rubber;

[0012] ⑤ Add sulfur to polyisobutylene-modified butyl rubber and continue mixing to obtain a semi-conductive colloidal material;

[0013] II. Preparation of Semiconductor Butyl Buffer Layer Composite Tape:

[0014] ① Embed the square metal sheet into the square metal frame to obtain the mold; cut the semi-conductive base coating to the same size as the square metal sheet and lay it flat on the surface of the square metal sheet; then coat the surface of the semi-conductive base coating with the semi-conductive colloidal material; and then place the mold containing the semi-conductive colloidal material in the flat vulcanizing machine.

[0015] ② First, the pre-compression is carried out in sections at 80℃ using a gradient pressure increase method. Then, the temperature and pressure are maintained at 170℃ and 15MPa to complete the cross-linking and vulcanization. After that, the semiconductive bottom coating is separated from the square metal sheet to obtain a wide temperature range semiconductive butyl buffer layer composite tape.

[0016] Advantages of this invention:

[0017] This invention discloses a semiconducting butyl buffer layer composite tape that possesses the core advantages of intrinsic long-lasting water resistance, low resistance over a wide temperature range, and stable performance under long-term thermal aging. The composite tape uses butyl rubber (IIR), which has excellent intrinsic water resistance and airtightness, as the matrix. Low molecular weight polyisobutylene (PIB) is added to improve the material's low-temperature resistance and toughness. A semiconducting compound is prepared by melt blending the IIR with conductive fillers, antioxidant 4010NA, and other functional fillers. This compound is then combined with a semiconducting undercoat to form a double-layer structure tape. Testing shows that it achieves long-lasting water resistance without relying on water-blocking powder, maintains low volume resistivity across a wide temperature range of -40℃ to 100℃, and shows no significant performance degradation after 7×24h continuous thermal aging. It also possesses a certain degree of viscosity, making it suitable for the full-condition operation requirements of high-voltage cable buffer layers. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention;

[0019] Figure 2 This is a comparison diagram of the composite tape prepared by the coating method in Comparative Example 1 and the composite tape prepared by the integrated hot pressing process in Example 1.

[0020] Figure 3 The images are SEM images. In the image, (a) is the semiconductive colloidal material prepared in step one of Example 1, and (b) is a cross-sectional view of the composite tape of the semiconductive undercoat and the wide temperature range semiconductive butyl buffer layer in Example 1.

[0021] Figure 4 The FTIR-ATR curve of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1;

[0022] Figure 5 The volume resistivity of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 before and after thermal aging.

[0023] Figure 6 The hydrophilicity and hydrophobicity angles of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 before and after thermal aging;

[0024] Figure 7 The tensile curves of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 before and after thermal aging are shown. Detailed Implementation

[0025] Specific Implementation Method 1: This implementation method is a method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape, specifically completed according to the following steps:

[0026] I. Preparation of Semiconducting Colloidal Materials:

[0027] ① Add butyl rubber to a mixer for plasticizing to obtain plasticized butyl rubber;

[0028] ② Mix carbon black A, carbon black B, graphene and carbon nanotubes evenly to obtain functional filler; add functional filler to plasticized butyl rubber and mix to obtain functional filler modified butyl rubber.

[0029] ③ Add stearic acid, zinc oxide, antioxidant and paraffin to functional filler modified butyl rubber, and continue to mix to obtain additive modified butyl rubber;

[0030] ④ Add polyisobutylene to the additive-modified butyl rubber and continue to mix to obtain polyisobutylene-modified butyl rubber;

[0031] ⑤ Add sulfur to polyisobutylene-modified butyl rubber and continue mixing to obtain a semi-conductive colloidal material;

[0032] II. Preparation of Semiconductor Butyl Buffer Layer Composite Tape:

[0033] ① Embed the square metal sheet into the square metal frame to obtain the mold; cut the semi-conductive base coating to the same size as the square metal sheet and lay it flat on the surface of the square metal sheet; then coat the surface of the semi-conductive base coating with the semi-conductive colloidal material; and then place the mold containing the semi-conductive colloidal material in the flat vulcanizing machine.

[0034] ② First, the pre-compression is carried out in sections at 80℃ using a gradient pressure increase method. Then, the temperature and pressure are maintained at 170℃ and 15MPa to complete the cross-linking and vulcanization. After that, the semiconductive bottom coating is separated from the square metal sheet to obtain a wide temperature range semiconductive butyl buffer layer composite tape.

[0035] In step 1① of this embodiment, butyl rubber (IIR) is plasticized. Its core function is to reduce the molecular weight of raw rubber, improve plasticity and flowability, and lay the foundation for subsequent processing. The plasticized rubber is more conducive to blending with subsequent fillers.

[0036] In step 1② of this embodiment, the molecular particle size of the functional fillers is different. As the fillers are continuously added, due to the filler network effect, the torque of the internal mixer in this stage shows a clear increasing trend from low to high.

[0037] In step 1, ③ of this embodiment, stearic acid and zinc oxide are added to the functional filler-modified butyl rubber. The zinc stearate generated by the reaction of the two is a vulcanization activation center with higher activity than zinc oxide alone, which can maximize the improvement of vulcanization efficiency and product performance.

[0038] In step 1, ④ of this embodiment, polyisobutylene (PIB) is added. PIB has excellent compatibility with butyl rubber (IIR) matrix, which can reduce the glass transition temperature of the material, improve the performance of the material in a low temperature environment of -40℃, and broaden the low temperature application range of the material. On the other hand, it can improve the initial tack of the rubber compound itself and strengthen the interfacial adhesion performance with the semiconductive substrate. At the same time, this non-polar polymer will not destroy the multi-level continuous conductive pathways constructed by carbon black, carbon nanotubes, and graphene, ensuring the stability of resistivity across the entire temperature range.

[0039] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the plasticizing temperature in step one ① is 70°C~80°C, the rotor speed is 40r / min~50r / min, and the plasticizing time is 4min~6min. The other steps are the same as in Specific Implementation Method One.

[0040] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the carbon black A mentioned in step one ② is LK400, purchased from Shandong Lianke Technology Co., Ltd.; the carbon black B is C320, purchased from Xinxiang Delong Chemical Co., Ltd.; and the carbon nanotubes used in step one ② are multi-walled carbon nanotubes. Other steps are the same as in Specific Implementation Method One or Two.

[0041] The carbon black A described in this embodiment has excellent reinforcing properties. When filled into a butyl rubber matrix, it can significantly improve the tensile strength, tear strength, and elongation at break of the rubber compound.

[0042] The carbon black B described in this embodiment has outstanding conductivity, which can quickly build a continuous conductive path inside the rubber compound and precisely control the volume resistivity of the rubber compound.

[0043] This embodiment combines two carbon black compounds to achieve synergistic effects, while also considering the mechanical and semi-conductive properties of the composite tape, thus meeting the usage requirements under a wide temperature range.

[0044] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the mass ratio of carbon black A, carbon black B, graphene, and carbon nanotubes in step one ② is (20~30):(10~15):(5~10):(5~10); the mass ratio of carbon black A in step one ② to butyl rubber in step one ① is (20~30):100. Other steps are the same as in Specific Implementation Methods One to Three.

[0045] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in the following ways: the antioxidant mentioned in step 1.③ is antioxidant 4010NA; the mass ratio of stearic acid, zinc oxide, antioxidant, and paraffin wax in step 1.③ is (0.5~0.8):(0.3~0.5):(8~10):(8~10); the mass ratio of stearic acid mentioned in step 1.③ to butyl rubber mentioned in step 1.① is (0.5~0.8):100. Other steps are the same as in Specific Implementation Methods One to Four.

[0046] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the mass ratio of polyisobutylene in step one ④ to butyl rubber in step one ① is (5~7):100; the mass ratio of sulfur in step one ⑤ to butyl rubber in step one ① is (2~4):100. The other steps are the same as in Specific Implementation Methods One to Five.

[0047] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in the following ways: the mixing temperature in step one is 70°C~80°C, and the rotor speed is 40r / min~50r / min; the mixing time in step one ② is 10min~15min; the continued mixing time in step one ③ is 5min~7min; the mixing time in step one ④ is 3min~4min; the polyisobutylene in step one ④ has a molecular weight of 2400 and was purchased from Daelim Corporation, South Korea; the mixing time in step one ⑤ is 4min~8min. Other steps are the same as in Specific Implementation Methods One to Six.

[0048] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in the following ways: the size of the square thin iron sheet mentioned in step two ① is 100mm × 100mm × 0.65mm; the size of the square iron frame mentioned in step two ① is 120mm × 120mm × 1mm; the material of the semi-conductive base coating mentioned in step two ① is nylon; and the metal mentioned in step two ① is iron. Other steps are the same as in Specific Implementation Methods One to Seven.

[0049] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the thickness of the semiconductive base coating in step two ① is 0.1 mm; the thickness of the wide-temperature-range semiconductive butyl buffer layer composite tape obtained in step two ② is 0.3 mm to 0.35 mm. Other steps are the same as in Specific Implementation Methods One to Eight.

[0050] Specific Implementation Method Ten: The difference between this implementation method and Specific Implementation Methods One to Nine is as follows: In step two ②, the method of segmented pre-compression at 80℃ using a gradient pressure increase is as follows: First, maintain the temperature and pressure at 80℃ and 0MPa for 10-12 minutes; then maintain the temperature and pressure at 80℃ and 5MPa for 5-7 minutes; then maintain the temperature and pressure at 80℃ and 10MPa for 5-7 minutes; finally, maintain the temperature and pressure at 80℃ and 15MPa for 5-7 minutes. In step two ②, maintain the temperature and pressure at 170℃ and 15MPa for 10-15 minutes. Other steps are the same as in Specific Implementation Methods One to Nine.

[0051] The beneficial effects of the present invention are verified using the following embodiments:

[0052] Example 1: A method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape, specifically completed according to the following steps:

[0053] I. Preparation of Semiconducting Colloidal Materials:

[0054] ① Add 100 parts of butyl rubber (IIR) to a mixer for plasticizing to obtain plasticized butyl rubber;

[0055] The plasticizing temperature in step 1① is 90°C, the rotor speed is 30 r / min, and the plasticizing time is 5 min;

[0056] ② Mix 25 parts of carbon black A, 15 parts of carbon black B, 5 parts of graphene and 5 parts of carbon nanotubes evenly to obtain a functional filler; add the functional filler to the plasticized butyl rubber and mix for 10 minutes at 90°C and a rotor speed of 30 r / min to obtain functional filler modified butyl rubber.

[0057] The carbon black A mentioned in step 1② is LK400, purchased from Shandong Lianke Technology Co., Ltd.; the carbon black B mentioned is C320, purchased from Xinxiang Delong Chemical Co., Ltd.

[0058] The carbon nanotubes used in step 1② are multi-walled carbon nanotubes;

[0059] ③ Add 0.5 parts stearic acid, 0.3 parts zinc oxide, 8 parts antioxidant 4010NA and 10 parts paraffin to the functional filler modified butyl rubber, and continue to mix for 5 minutes to obtain additive modified butyl rubber.

[0060] ④ Add 5 parts of polyisobutylene (PIB) to the additive-modified butyl rubber and continue mixing for 3 minutes to obtain polyisobutylene-modified butyl rubber.

[0061] The polyisobutylene mentioned in step 1, section 4 has a molecular weight of 2400 and was purchased from Daelim Corporation in South Korea.

[0062] ⑤ Add 2 parts of sulfur to polyisobutylene-modified butyl rubber and continue mixing for 4 minutes to obtain a semi-conductive colloidal material.

[0063] II. Preparation of Semiconductor Butyl Buffer Layer Composite Tape:

[0064] ① Embed the square iron sheet into the square iron frame to obtain the mold; cut the 0.1mm thick semi-conductive base coating to the same size as the square iron sheet and lay it flat on the surface of the square iron sheet; then coat the surface of the semi-conductive base coating with semi-conductive colloid material; and then place the mold containing the semi-conductive colloid material in the flat vulcanizing machine.

[0065] The square thin iron sheet mentioned in step 2① has dimensions of 100mm × 100mm × 0.65mm;

[0066] The square iron frame mentioned in step 2① has dimensions of 120mm × 120mm × 1mm;

[0067] The material of the semiconductive base coating mentioned in step 2① is nylon;

[0068] ② First, the semi-conductive coating is pre-pressed in sections at 80℃ using a gradient pressure increase method. Then, it is kept at 170℃ and 15MPa for 10 minutes to complete the cross-linking and vulcanization. After that, the semi-conductive coating is separated from the square metal sheet to obtain a wide temperature range semi-conductive butyl buffer layer composite tape (IIR / CB) with a thickness of 0.35mm.

[0069] The method of segmented pre-compression in step 2② at 80℃ using gradient pressure is as follows: first, maintain the temperature and pressure at 80℃ and 0MPa for 10 minutes, then maintain the temperature and pressure at 80℃ and 5MPa for 5 minutes, then maintain the temperature and pressure at 80℃ and 10MPa for 5 minutes, and finally maintain the temperature and pressure at 80℃ and 15MPa for 10 minutes.

[0070] Comparative Example 1: The method for preparing composite tape using a coating method is specifically carried out according to the following steps:

[0071] Uncrosslinked semiconductive butyl rubber composite material was cut into granules and placed into a beaker of appropriate size. A certain mass of solvent oil was added to the beaker, with a solute mass fraction of 13% to 15%. The beaker was placed in a heated magnetic stirrer with a speed of 800 r / min and heated and stirred for 12 h at a temperature of 50℃. After the rubber was fully dissolved, a semiconductive butyl rubber solution was obtained.

[0072] The base fabric is laid flat on an automatic coating machine, and a semi-conductive butyl rubber solution is poured in. The coating machine is used to automatically coat the rubber at a low speed. Then, the prepared semi-conductive butyl tape is placed in an 80°C oven and taken out for use after 15 minutes. Finally, the semi-conductive butyl tape is placed in a 170°C oven and the rubber layer is vulcanized after 10 minutes, thus obtaining the cable semi-conductive butyl rubber buffer layer.

[0073] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention;

[0074] The wide-temperature-range semiconducting butyl buffer layer composite tape (thickness of 0.35 mm) prepared in Example 1 meets the thickness requirements of the national standard T / CEEIA 610—2022 "Semiconducting wrapping tape for buffer layer of power cable with rated voltage of 110 kV and above".

[0075] Figure 2 This is a comparison diagram of the composite tape prepared by the coating method in Comparative Example 1 and the composite tape prepared by the integrated hot pressing process in Example 1.

[0076] from Figure 2 It can be seen that the present invention adopts an integrated hot pressing process, resulting in a smooth surface and uniform thickness of the sheet. Compared with the traditional process of dissolving and then coating, it has obvious advantages and will not have problems such as uneven coating.

[0077] Figure 3 The images are SEM images. In the image, (a) is the semiconductive colloidal material prepared in step one of Example 1, and (b) is a cross-sectional view of the composite tape of the semiconductive undercoat and the wide temperature range semiconductive butyl buffer layer in Example 1.

[0078] from Figure 3 (a) It can be seen that the white fine dots at the cross-section represent the distribution of filler in the butyl rubber. The filler is uniformly distributed overall, and there is no large filler agglomeration. Figure 3 (b) is a cross-section of a composite tape with a semiconductive undercoat and a wide-temperature-range semiconductive butyl buffer layer, with clear boundaries between the layers. Figure 3 In the upper half of (b), the fibers of the base coating are clearly exposed, while the colloidal material in the lower half is generally compact. The two layers are tightly bonded together without significant delamination, demonstrating the superiority of the integrated hot-pressing process.

[0079] Figure 4 The FTIR-ATR curve of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1;

[0080] from Figure 4 It can be seen that at 2916cm -1 and 2848cm -1The absorption peak at 1461 cm⁻¹ corresponds to the stretching vibration absorption peaks of the methyl (-CH₃-) and methylene (-CH₂-) groups in the isobutylene and isoprene structural units. -1 The peak at 1383 cm⁻¹ represents the overlap of the asymmetric bending vibration of the methyl group and the scissor bending vibration of the methylene group. -1 and 1361cm -1 A set of sharp peaks, representing the symmetric bending vibrations of two methyl groups on the isopropyl backbone, at 1225 cm⁻¹. -1 The absorption peak is generated by the rocking vibration of the methyl group.

[0081] Figure 5 The volume resistivity of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 before and after thermal aging.

[0082] from Figure 5 It can be seen that within the tested temperature range, the volume resistivity of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 reaches its maximum value between 60℃ and 70℃, satisfying the PTC effect of semiconductor materials. That is, as the temperature increases, the volume resistivity of the semiconductor tends to increase, and after reaching its maximum value, the volume resistivity decreases with increasing temperature. Comparing the volume resistivity test before aging, it was found that the volume resistivity increased slightly after aging. Within the low-temperature range, the resistivity tends to stabilize before and after thermal aging, with a small change. This is because the material is in a low-resistivity state dominated by impurity ionization, and the resistivity is the "lower value" in the entire temperature range.

[0083] Figure 6 The hydrophilicity and hydrophobicity angles of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 before and after thermal aging;

[0084] The industry uses 90° as the critical value separating the hydrophilic and hydrophobic properties of materials. Figure 6 It can be seen that the water contact angle of the unaged sample is 100.42°, which is higher than the critical standard of 90°, indicating that the substrate has excellent hydrophobic and water-blocking properties. After high-temperature accelerated thermal aging treatment, the contact angle of the sample decreased slightly to 95.2°, and the hydrophobic properties were slightly reduced, but the value is still higher than the critical threshold for hydrophobicity.

[0085] Figure 7 The tensile curves of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 before and after thermal aging are shown.

[0086] from Figure 7 It can be seen that the unaged sample has a complete cross-linking network and the carbon black is evenly dispersed in the rubber matrix, with both high tensile strength and elongation at break. After high-temperature accelerated thermal aging, the rubber matrix undergoes molecular chain breakage and local over-cross-linking under the action of heat and oxygen, and the tensile strength and elongation at break of the sample decrease to a certain extent simultaneously.

[0087] Table 1 shows the resistivity test data of the wide-temperature-range semiconductor butyl buffer layer composite tape prepared in step two of Example 1 before and after thermal aging.

[0088] As shown in Table 1, the initial volume resistivity of the wide-temperature-range semiconducting butyl buffer composite tape prepared in step two of Example 1 is 3250 Ω·cm, which is lower than the upper limit threshold of 5000 Ω·cm for semiconducting materials, meeting the electrical performance requirements of cable buffer layers. The corresponding initial surface resistivity is 44 Ω, indicating excellent conductivity. After high-temperature accelerated thermal aging treatment, due to the thermo-oxidative aging of the rubber matrix and the thermal migration and precipitation of a small amount of filler which damaged the local conductive network, the volume resistivity of the material increased to 4599.60 Ω·cm and the surface resistivity increased to 74 Ω. Both electrical parameters increased slightly, but the volume resistivity after aging was still far below the standard limit of 1×10⁵ Ω·cm, indicating excellent conductivity stability.

[0089] Table 1

[0090]

Claims

1. A method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of Semiconducting Colloidal Materials: ① Add butyl rubber to a mixer for plasticizing to obtain plasticized butyl rubber; ② Mix carbon black A, carbon black B, graphene and carbon nanotubes evenly to obtain functional filler; add functional filler to plasticized butyl rubber and mix to obtain functional filler modified butyl rubber. ③ Add stearic acid, zinc oxide, antioxidant and paraffin to functional filler modified butyl rubber, and continue to mix to obtain additive modified butyl rubber; ④ Add polyisobutylene to the additive-modified butyl rubber and continue to mix to obtain polyisobutylene-modified butyl rubber; ⑤ Add sulfur to polyisobutylene-modified butyl rubber and continue mixing to obtain a semi-conductive colloidal material; II. Preparation of Semiconductor Butyl Buffer Layer Composite Tape: ① Embed the square metal sheet into the square metal frame to obtain the mold; cut the semi-conductive base coating to the same size as the square metal sheet and lay it flat on the surface of the square metal sheet; then coat the surface of the semi-conductive base coating with the semi-conductive colloidal material; and then place the mold containing the semi-conductive colloidal material in the flat vulcanizing machine. ② First, the pre-compression is carried out in sections at 80℃ using a gradient pressure increase method. Then, the temperature and pressure are maintained at 170℃ and 15MPa to complete the cross-linking and vulcanization. After that, the semiconductive bottom coating is separated from the square metal sheet to obtain a wide temperature range semiconductive butyl buffer layer composite tape.

2. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The plasticizing temperature in step 1① is 70°C~80°C, the rotor speed is 40r / min~50r / min, and the plasticizing time is 4min~6min.

3. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The carbon black A mentioned in step 1② is LK400, purchased from Shandong Lianke Technology Co., Ltd.; the carbon black B is C320, purchased from Xinxiang Delong Chemical Co., Ltd.; the carbon nanotubes used in step 1② are multi-walled carbon nanotubes.

4. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The mass ratio of carbon black A, carbon black B, graphene and carbon nanotubes mentioned in step 1② is (20~30):(10~15):(5~10):(5~10); the mass ratio of carbon black A mentioned in step 1② to butyl rubber mentioned in step 1① is (20~30):

100.

5. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The antioxidant mentioned in step 1, ③ is antioxidant 4010NA; the mass ratio of stearic acid, zinc oxide, antioxidant and paraffin wax mentioned in step 1, ③ is (0.5~0.8):(0.3~0.5):(8~10):(8~10); the mass ratio of stearic acid mentioned in step 1, ③ to butyl rubber mentioned in step 1, ① is (0.5~0.8):

100.

6. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The mass ratio of polyisobutylene mentioned in step 1 ④ to butyl rubber mentioned in step 1 ① is (5~7):100; the mass ratio of sulfur mentioned in step 1 ⑤ to butyl rubber mentioned in step 1 ① is (2~4):

100.

7. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The mixing temperature in step one is 70°C~80°C, and the rotor speed is 40r / min~50r / min; the mixing time in step one ② is 10min~15min; the continued mixing time in step one ③ is 5min~7min; the mixing time in step one ④ is 3min~4min; the polyisobutylene in step one ④ has a molecular weight of 2400 and was purchased from Daelim Corporation, South Korea; the mixing time in step one ⑤ is 4min~8min.

8. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The square thin iron sheet mentioned in step 2① has dimensions of 100mm×100mm×0.65mm; the square iron frame mentioned in step 2① has dimensions of 120mm×120mm×1mm; the semi-conductive base coating material mentioned in step 2① is nylon; the metal mentioned in step 2① is iron.

9. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The thickness of the semiconductive substrate coating mentioned in step 2① is 0.1 mm; the thickness of the wide temperature range semiconductive butyl buffer layer composite tape obtained in step 2② is 0.3 mm to 0.35 mm.

10. The method for preparing a wide-temperature-range semiconductor butyl buffer layer composite tape according to claim 1, characterized in that... The method for segmented pre-compression at 80℃ using a gradient pressure increase in step 2② is as follows: first, maintain the temperature and pressure at 80℃ and 0MPa for 10min~12min, then maintain the temperature and pressure at 80℃ and 5MPa for 5min~7min, then maintain the temperature and pressure at 80℃ and 10MPa for 5min~7min, and finally maintain the temperature and pressure at 80℃ and 15MPa for 5min~7min; in step 2②, maintain the temperature and pressure at 170℃ and 15MPa for 10min~15min.

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