Polyisobutylene high strength electrical wire cable and method of making same

Abstract

The present application relates to the technical field of cable, in particular to a polyisobutylene high-strength wire cable and a preparation method thereof, which comprises a conductor, an insulation layer and a protective sleeve, and the protective sleeve comprises the following raw materials: polyisobutylene, maleic anhydride grafted polypropylene, nano filler, polyisobutylene grafted cage polysilsesquioxane composite, resorcinol bis(diphenyl phosphate) and 2,6-di-tert-butyl-4-methylphenol. By covalently grafting cage polysilsesquioxane nanostructure on the polyisobutylene molecular chain, the tensile strength, heat distortion temperature and creep resistance of the material can be improved, while the elongation at break matching the matrix is maintained, so that the cable outer sheath can still maintain excellent dimensional stability and dielectric properties under high temperature, high stress and humid environment. At the same time, the cage polysilsesquioxane nano skeleton has high thermal stability and space shielding effect, which can effectively inhibit the thermal oxidative aging and molecular chain movement of polyisobutylene, and improve the long-term weather resistance and creep resistance.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and more specifically, to polyisobutylene high-strength wires and cables and their preparation methods. Background Technology

[0002] As carriers of power transmission and signal transmission, the performance of the protective sheath of wires and cables determines the durability and safety of the product. Traditional polymer systems such as polyvinyl chloride, cross-linked polyethylene, ethylene propylene rubber, and polyisobutylene are widely used in medium and low voltage cable sheaths due to their good insulation and flexibility. However, conventional polyisobutylene materials have flexible molecular chains and low crystallinity. Although they have excellent weather resistance and dielectric stability, their tensile strength, heat distortion temperature, and creep resistance are low. Under long-term load or high temperature environment, they are prone to structural relaxation, which leads to deformation, cracking, or decreased insulation performance of the outer sheath layer.

[0003] In existing technologies, physical modification is usually achieved by filling the polyisobutylene matrix with inorganic nanoparticles (such as SiO2, Al2O3, etc.) or by blending it with other polyolefins. However, most of these methods rely on physical adsorption or weak interactions (such as van der Waals forces and hydrogen bonds) between the filler and the matrix, making it difficult to form strong chemical bonds at the interface. This leads to the material being prone to microcracks due to interfacial debonding under harsh conditions such as thermo-oxidative aging, high-frequency mechanical bending, or strong electric fields. These microcracks propagate rapidly, causing sheath failure and degrading cable performance. In view of this, we propose polyisobutylene high-strength wires and cables and their preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide high-strength polyisobutylene wires and cables and their preparation methods, in order to solve the problem that conventional methods mentioned in the background art mostly rely on physical adsorption or weak interactions (such as van der Waals forces and hydrogen bonds) between the filler and the matrix, making it difficult to form strong chemical bonds at the interface. This leads to the problem that under harsh conditions such as thermo-oxidative aging, high-frequency mechanical bending, or strong electric fields, the material is prone to microcracks due to interface debonding, which then propagate rapidly, causing sheath failure and cable performance degradation.

[0005] This invention provides a high-strength polyisobutylene wire and cable, comprising a conductor, an insulation layer, and a protective sheath. The protective sheath comprises the following raw materials: polyisobutylene, maleic anhydride-grafted polypropylene, nanofiller, polyisobutylene-grafted cage-type polysilsesquioxane composite, resorcinol bis(diphenyl phosphate), and 2,6-di-tert-butyl-4-methylphenol.

[0006] The polyisobutylene-grafted cage-type polysilsesquioxane composite is prepared by covalent grafting of polyisobutylene and vinyl isobutylated cage-type silsesquioxane via free radical reaction.

[0007] Preferably, the protective sleeve comprises the following raw materials in parts by weight: 70-85 parts by weight of polyisobutylene, 5-8 parts by weight of maleic anhydride-grafted polypropylene, 3-5 parts by weight of nanofiller, 4-6 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite, 5-10 parts by weight of resorcinol bis(diphenyl phosphate) and 0.3-0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol.

[0008] Preferably, the preparation method of the polyisobutylene-grafted cage-type polysilsesquioxane composite is as follows:

[0009] Under a nitrogen atmosphere, polyisobutylene and vinyl isobutylated cage-type polysilsesquioxane are mixed and then melt-dispersed in a twin-screw extruder at a barrel temperature of 170-200℃ and a screw speed of 200-300 rpm. Di-tert-butyl peroxide is then added, and the reaction continues for 5-10 minutes to obtain the final material. After the reaction, the material is extruded into a circulating water cooling tank at a temperature of 10-40℃ for solidification. It is then granulated using a pelletizer to obtain pellets with a length of 2-5 mm. The pellets are then heat-treated at 120-160℃ for 5-10 minutes to obtain the polyisobutylene-grafted cage-type polysilsesquioxane composite.

[0010] Preferably, the mass ratio of the polyisobutylene to the vinylisobutylated cage-like silsesquioxane is 100:2-4.

[0011] Preferably, the amount of di-tert-butyl peroxide added is 0.1-0.3% of the mass of polyisobutylene.

[0012] On the other hand, the present invention provides a method for preparing polyisobutylene high-strength wires and cables, which includes the following steps:

[0013] S1.1 Polyethylene containing 2.5% dicumyl peroxide is extruded and coated onto tin-plated copper wire at 130-150℃ to obtain an uncrosslinked insulation layer; then it is treated in a nitrogen atmosphere at a pressure of 0.6-1.2MPa and a temperature of 180-200℃ for 10-20 minutes, and finally cooled and shaped to obtain a crosslinked polyethylene insulation layer.

[0014] S1.2, 70-85 parts by weight of polyisobutylene, 5-8 parts by weight of maleic anhydride-grafted polypropylene, 3-5 parts by weight of nanofiller, 4-6 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite, 5-10 parts by weight of resorcinol bis(diphenyl phosphate) and 0.3-0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol are added to a high-speed mixer and melt-blended under nitrogen protection at 170-190°C to obtain a molten material;

[0015] S1.3. The molten material is passed through the die of an extruder and the outer sheath is extruded and coated onto the insulation layer at 170-190℃. After extrusion, the material is cooled and shaped in a water bath to obtain a cable semi-finished product. Subsequently, the cable semi-finished product is heat-treated, and finally cooled, drawn and wound to obtain a polyisobutylene high-strength wire and cable.

[0016] Preferably, in step S1.2, 1.0-2.5% of the mass of polyisobutylene is added during the last 2 minutes of melt blending as bis(2-mercaptoethyl) sulfone disulfide.

[0017] Preferably, in step S1.2, the preparation method of the nanofiller is as follows: nano-silica is dispersed in ethanol at 60°C at a mass ratio of 1:20, and 5-15% of methacryloyloxypropyltrimethoxysilane is added, and the reaction is carried out for 4-6 hours; after the reaction is completed, the nanofiller is filtered, washed, and then dried at -0.08MPa and 80-120°C for 3-5 hours to obtain the nanofiller.

[0018] Preferably, in S1.3, the screw speed of the extruder for extruding the coating is 80-120 rpm, the extrusion speed is 2-6 m / min, and the molding pressure is 20-50 bar.

[0019] Preferably, in step S1.3, the heat treatment process is carried out under segmented heating conditions: first, preheating at 90-110℃ for 5 minutes, and then heating to 120-130℃ for 10-15 minutes.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] In this invention, a high-strength polyisobutylene wire and cable and its preparation method are disclosed. A cage-like polysilsesquioxane nanostructure is covalently grafted onto the polyisobutylene molecular chain, constructing an organic-inorganic integrated nano-reinforcing phase. This achieves interfacial chemical bonding and molecular-level mechanical synergy. This structure significantly improves the material's tensile strength, heat distortion temperature, and creep resistance, while maintaining a breaking elongation matching the matrix. This allows the cable sheath to maintain excellent dimensional stability and dielectric properties even under high temperature, high stress, and humid environments. Furthermore, the cage-like polysilsesquioxane nanoframework possesses high thermal stability and a spatial shielding effect, effectively inhibiting the thermo-oxidative aging and molecular chain movement of polyisobutylene, thus enhancing long-term weather resistance and creep resistance. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a high-strength polyisobutylene wire and cable, comprising a conductor, an insulation layer, and a protective sheath. The protective sheath comprises the following raw materials: polyisobutylene, maleic anhydride-grafted polypropylene, nanofiller, polyisobutylene-grafted cage-type polysilsesquioxane composite, resorcinol bis(diphenyl phosphate), and 2,6-di-tert-butyl-4-methylphenol.

[0024] The polyisobutylene-grafted cage-type polysilsesquioxane composite is prepared by covalent grafting of polyisobutylene and vinyl isobutylated cage-type silsesquioxane via free radical reaction.

[0025] Polyisobutylene (CAS No.: 9003-27-4, molecular weight 300,000), methacryloyloxypropyltrimethoxysilane (CAS No.: 2530-85-0, purity BR, 98%), and 2,6-di-tert-butyl-4-methylphenol (CAS No.: 128-37-0, purity 98%) were all purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0026] Maleic anhydride-grafted polypropylene was purchased from Nanjing Bermuda Biotechnology Co., Ltd.

[0027] The vinyl isobutylated cage-like silsesquioxane was purchased from Shaanxi Xingbei Aike Biotechnology Co., Ltd.

[0028] Di-tert-butyl peroxide (CAS No.: 110-05-4, purity 99%) was purchased from Hubei Rishengchang New Material Technology Co., Ltd.

[0029] Bis(2-mercaptoethyl) sulfone disulfide (CAS No.: 145626-93-3) was purchased from Shanghai Chamu Analytical Technology Co., Ltd.

[0030] Nano silica (99% purity; product number ML-SiO2) was purchased from Zhejiang Manli Nanotechnology Co., Ltd.

[0031] Resorcinol bis(diphenyl phosphate) (CAS No.: 125997-21-9, purity 99%) was purchased from Wuhan Prof Biotechnology Co., Ltd.

[0032] The preparation method of the nanofiller is as follows: Nano-silica is dispersed in ethanol at 60℃ at a mass ratio of 1:20, and methacryloyloxypropyltrimethoxysilane accounting for 10% of the mass of nano-silica is added. The reaction is carried out for 5 hours. After the reaction is completed, the nanofiller is filtered, washed, and then dried at -0.08MPa and 100℃ for 4 hours to obtain the nanofiller.

[0033] Example 1: A method for preparing high-strength polyisobutylene wires and cables, comprising the following steps:

[0034] S1.1 Polyethylene containing 2.5% dicumyl peroxide is extruded at 130°C and coated onto tin-plated copper wire to obtain an uncrosslinked insulation layer; then it is treated in a nitrogen atmosphere at 0.6 MPa and 180°C for 10 min, and finally cooled and shaped to obtain a crosslinked polyethylene insulation layer.

[0035] S1.2. 70 parts by weight of polyisobutylene, 5 parts by weight of maleic anhydride-grafted polypropylene, 3 parts by weight of nanofiller, 4 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite, 5 parts by weight of resorcinol bis(diphenyl phosphate) and 0.3 parts by weight of 2,6-di-tert-butyl-4-methylphenol are added to a high-speed mixer and melt-blended at 170°C under nitrogen protection. Finally, 1.0% of the mass of polyisobutylene, bis(2-mercaptoethyl) sulfone disulfide is added for the last 2 minutes to obtain the molten material.

[0036] S1.3. The molten material is extruded through the die of an extruder at 170°C to form an outer sheath covering of the insulation layer. The screw speed is 80 rpm, the extrusion speed is 2 m / min, and the molding pressure is 20 bar. After extrusion, the material is cooled and shaped in a water bath to obtain a semi-finished cable. The semi-finished cable is then heat-treated by preheating at 90°C for 5 min, then heating to 120°C for 10 min, and finally cooling, drawing, and winding to obtain a polyisobutylene high-strength wire and cable.

[0037] The preparation method of polyisobutylene-grafted cage-type polysilsesquioxane composite is as follows:

[0038] Under a nitrogen atmosphere, polyisobutylene and vinyl isobutylated cage-type polysilsesquioxane were mixed (mass ratio 100:3) and then melt-dispersed in a twin-screw extruder at a barrel temperature of 170°C and a screw speed of 200 rpm. Subsequently, 0.2% by weight of di-tert-butyl peroxide was added, and the reaction was continued for 5 minutes to obtain the material. After the reaction was completed, the material was extruded into a circulating water cooling tank at a water temperature of 10°C for solidification, and then granulated by a pelletizer to obtain pellets with a length of 2 mm. The pellets were then heat-treated at 120°C for 5 minutes to obtain a polyisobutylene-grafted cage-type polysilsesquioxane composite.

[0039] Example 2: The difference between this example and Example 1 is that the mass ratio of polyisobutylene to vinyl isobutylated cage-like silsesquioxane is 100:2.

[0040] Example 3: The difference between this example and Example 1 is that the mass ratio of polyisobutylene to vinyl isobutylated cage-like silsesquioxane is 100:4.

[0041] Example 4: The difference between this example and Example 1 is that the amount of di-tert-butyl peroxide added is 0.1% of the mass of polyisobutylene.

[0042] Example 5: The difference between this example and Example 1 is that the amount of di-tert-butyl peroxide added is 0.3% of the mass of polyisobutylene.

[0043] Grafting rate determination: Fourier transform infrared spectroscopy (FTIR) was used, by measuring the characteristic peak of vinyl groups before and after grafting (approximately 1600 cm⁻¹). -1 The degree of attenuation and the characteristic peak of Si-O-Si (approximately 1100 cm⁻¹) -1 The grafting rate is calculated based on the relative intensity change of the grafting rate.

[0044] Determination of thermal stability: Take 5-10 mg of dried sample and place it in a platinum crucible of the TGA instrument. Under a high-purity nitrogen atmosphere (flow rate usually 50-60 mL / min), heat from room temperature to 800℃ at a heating rate of 10℃ / min. Record and compare the thermogravimetric curves. Record the initial decomposition temperature (usually the temperature at which the sample loses 5% of its weight). The higher this temperature, the better the initial thermal stability of the material.

[0045] Mechanical property determination: The composite granules (sheath) are thermoformed into standard dumbbell-shaped specimens; the specimens are placed in a standard laboratory environment (e.g., 23±2℃, 50±10% humidity) for at least 16 hours to eliminate internal stress; the specimens are tested on a universal tensile testing machine at room temperature at a constant tensile rate (e.g., 50 mm / min) until the specimen breaks; the tensile strength (maximum stress before fracture) and elongation at break are obtained from the stress-strain curve; successful grafting should result in a significant increase in tensile strength while maintaining good toughness.

[0046] Table 1 Performance data of polyisobutylene-grafted cage-type polysilsesquioxane composites

[0047] Grafting rate thermal stability Tensile strength Example 1 15.2% 485℃ 28.5MPa Example 2 10.5% 475℃ 25.1MPa Example 3 14.8% 488℃ 26.8MPa Example 4 12.1% 478℃ 26.9MPa Example 5 16.0% 482℃ 27.2MPa

[0048] As can be seen from Table 1 Examples 1-3, as the mass ratio of polyisobutylene to vinyl isobutylated cage-type silsesquioxane increases, the grafting rate and thermal stability both show a trend of first increasing and then slightly decreasing or remaining flat.

[0049] In Example 2, the amount of vinyl isobutylated cage-like silsesquioxane was insufficient, resulting in a limited number of rigid nanoparticles that could be used for grafting. Therefore, the improvement in grafting rate, thermal stability, and mechanical strength was the lowest.

[0050] In Example 3, the amount of vinyl isobutylated cage-like silsesquioxane was too high, which easily caused local agglomeration during melt blending, forming stress defect points. Although a large amount of vinyl isobutylated cage-like silsesquioxane brought the highest thermal stability, the agglomeration phenomenon led to a decrease in its mechanical strengthening effect, so the tensile strength was actually lower than that of Example 1.

[0051] Comparing Examples 1, 4, and 5, it can be seen that as the amount of di-tert-butyl peroxide increases from 0.1% to 0.3%, the grafting rate continues to increase, but the thermal stability and tensile strength are better at 0.2%.

[0052] In Example 4 (0.1%), the concentration of di-tert-butyl peroxide was insufficient, resulting in a small number of free radicals and low grafting efficiency, thus leading to the lowest grafting rate. The effect of the insufficiently grafted vinyl isobutylated cage-like silsesquioxane was limited, so none of the properties reached their optimal levels.

[0053] In Example 1 (0.2%), the amount of di-tert-butyl peroxide was moderate, and the grafting reaction was sufficient and controllable. While obtaining a high grafting rate, it did not cause serious damage to the polymer matrix, thus achieving a balance of performance.

[0054] Example 5 (0.3%) The high concentration of di-tert-butyl peroxide generated too many free radicals, which further increased the grafting rate, but also aggravated side reactions such as the breaking of polyisobutylene molecular chains or excessive cross-linking. This destroyed the integrity of the matrix structure, resulting in the matrix itself being damaged even though a lot of vinyl isobutylated cage-like silsesquioxanes were grafted on. Therefore, the mechanical strength and thermal stability both declined.

[0055] Example 6: A method for preparing high-strength polyisobutylene wires and cables, comprising the following steps:

[0056] S1.1 Polyethylene containing 2.5% dicumyl peroxide is extruded at 140°C and coated onto tin-plated copper wire to obtain an uncrosslinked insulation layer; then it is treated in a nitrogen atmosphere at 1.0 MPa and 190°C for 15 min, and finally cooled and shaped to obtain a crosslinked polyethylene insulation layer.

[0057] S1.2. 80 parts by weight of polyisobutylene, 6 parts by weight of maleic anhydride-grafted polypropylene, 4 parts by weight of nanofiller, 5 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite, 7 parts by weight of resorcinol bis(diphenyl phosphate) and 0.4 parts by weight of 2,6-di-tert-butyl-4-methylphenol are added to a high-speed mixer and melt-blended at 180°C under nitrogen protection. Finally, 2.0% of the mass of polyisobutylene, bis(2-mercaptoethyl) sulfone disulfide is added for the last 2 minutes to obtain the molten material.

[0058] S1.3. The molten material is extruded through the die of an extruder at 180°C to form an outer sheath covering of the insulation layer. The screw speed is 100 rpm, the extrusion speed is 4 m / min, and the molding pressure is 30 bar. After extrusion, the material is cooled and shaped in a water bath to obtain a semi-finished cable. The semi-finished cable is then heat-treated by preheating at 100°C for 5 minutes, then heating to 125°C for 12 minutes. Finally, it is cooled, drawn, and wound to obtain a polyisobutylene high-strength wire and cable.

[0059] The preparation method of polyisobutylene-grafted cage-type polysilsesquioxane composite is as follows:

[0060] Under a nitrogen atmosphere, polyisobutylene and vinyl isobutylated cage-type polysilsesquioxane were mixed (mass ratio 100:3) and then melt-dispersed in a twin-screw extruder at a barrel temperature of 180°C and a screw speed of 250 rpm. Subsequently, 0.2% by weight of di-tert-butyl peroxide was added, and the reaction was continued for 10 minutes to obtain the material. After the reaction was completed, the material was extruded into a circulating water cooling tank at a water temperature of 20°C for solidification, and then granulated by a pelletizer to obtain pellets with a length of 4 mm. The pellets were then heat-treated at 140°C for 10 minutes to obtain a polyisobutylene-grafted cage-type polysilsesquioxane composite.

[0061] Example 7: The difference between this example and Example 6 is that 4 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite are used.

[0062] Example 8: The difference between this example and Example 6 is that 6 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite are used.

[0063] Example 9: The difference between this example and Example 6 is that the bis(2-mercaptoethyl) sulfone disulfide accounts for 1.0% of the mass of polyisobutylene.

[0064] Example 10: The difference between this example and Example 6 is that bis(2-mercaptoethyl) sulfone disulfide accounts for 2.5% of the mass of polyisobutylene.

[0065] Example 11: A method for preparing high-strength polyisobutylene wires and cables, comprising the following steps:

[0066] S1.1 Polyethylene containing 2.5% dicumyl peroxide is extruded at 150°C and coated onto tin-plated copper wire to obtain an uncrosslinked insulation layer; then it is treated in a nitrogen atmosphere at 1.2 MPa and 200°C for 20 min, and finally cooled and shaped to obtain a crosslinked polyethylene insulation layer.

[0067] S1.2. 85 parts by weight of polyisobutylene, 8 parts by weight of maleic anhydride-grafted polypropylene, 5 parts by weight of nanofiller, 5 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite, 10 parts by weight of resorcinol bis(diphenyl phosphate) and 0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol are added to a high-speed mixer and melt-blended at 190°C under nitrogen protection. Finally, 1.0% of the mass of polyisobutylene, bis(2-mercaptoethyl) sulfone disulfide is added for the last 2 minutes to obtain the molten material.

[0068] S1.3. The molten material is extruded through the die of an extruder at 190°C to form an outer sheath covering of the insulation layer. The screw speed is 120 rpm, the extrusion speed is 6 m / min, and the molding pressure is 50 bar. After extrusion, the material is cooled and shaped in a water bath to obtain a semi-finished cable. The semi-finished cable is then heat-treated by preheating at 110°C for 5 minutes, then heating to 130°C for 15 minutes. Finally, it is cooled, drawn, and wound to obtain a polyisobutylene high-strength wire and cable.

[0069] The preparation method of polyisobutylene-grafted cage-type polysilsesquioxane composite is as follows:

[0070] Under a nitrogen atmosphere, polyisobutylene and vinyl isobutylated cage-type polysilsesquioxane were mixed (mass ratio 100:3) and then melt-dispersed in a twin-screw extruder at a barrel temperature of 200°C and a screw speed of 300 rpm. Subsequently, 0.2% by weight of di-tert-butyl peroxide was added, and the reaction was continued for 10 minutes to obtain the material. After the reaction was completed, the material was extruded into a circulating water cooling tank at a water temperature of 40°C for solidification, and then granulated by a pelletizer to obtain pellets with a length of 5 mm. The pellets were then heat-treated at 160°C for 10 minutes to obtain a polyisobutylene-grafted cage-type polysilsesquioxane composite.

[0071] Determination of thermal elongation properties: Strip specimens of specified dimensions are punched or cut from the sheath, a reference length is marked on the specimens, and a specific load (e.g., 20 N / cm) is applied. 2Then, the loaded specimen was placed in an oven at 200±3℃ and kept for 15 minutes; Elongation under load: At the end of 15 minutes, the length between the marks was measured immediately and the elongation relative to the original length was calculated; Permanent deformation rate: The specimen was removed from the oven, cooled to room temperature, and the load was removed. The length was measured again and the irreversible permanent deformation rate was calculated.

[0072] Table 2 Performance data of polyisobutylene high-strength wires and cables

[0073] Tensile strength Elongation at break Elongation under load Permanent deformation rate Example 6 30.2MPa 280% 85% 5% Example 7 27.5MPa 310% 90% 7% Example 8 29.8MPa 220% 88% 6% Example 9 26.0MPa 260% 150% 15% Example 10 31.0MPa 190% 75% 3%

[0074] As can be seen from Table 2, the amount of polyisobutylene-grafted cage-type polysilsesquioxane composite in Example 7 (4 parts) was too low, resulting in insufficient quantity of rigid nano-reinforcing phase and thus low tensile strength of the material; however, at the same time, due to the less rigid constraint on the crosslinked network, the molecular chains were more likely to stretch and slip during stretching, thus exhibiting a higher elongation at break; the thermal elongation performance was acceptable, but the strength was insufficient.

[0075] Example 6 provides sufficient polyisobutylene-grafted cage-type polysilsesquioxane composite to effectively enhance strength without excessively sacrificing the material's toughness; therefore, it exhibits high tensile strength, maintains a good level of elongation at break, and demonstrates excellent thermal elongation properties.

[0076] In Example 8, the amount of polyisobutylene-grafted cage-type polysilsesquioxane composite was too high. Although the tensile strength was still very high (close to Example 6), the excessive amount of polyisobutylene-grafted cage-type polysilsesquioxane composite particles began to hinder the large-scale movement of polymer molecular chains, resulting in a significant decrease in material toughness (lower elongation at break) and the material tending to be brittle. The thermal elongation performance was still good, but the insufficient toughness would affect the impact resistance.

[0077] Comparing Examples 6, 9, and 10, it can be concluded that the insufficient amount of crosslinking in Example 9 resulted in too few crosslinking points between polymer molecular chains and low crosslinking density. Therefore, when the material is heated and stressed, the molecular chains are prone to relative slippage, which manifests as low tensile strength and very poor thermal elongation performance (both elongation and permanent deformation rate under load are very high).

[0078] Example 6 shows that the crosslinking density is moderate, forming a stable yet non-rigid three-dimensional network. This network can effectively transfer stress, thus resulting in high tensile strength. At the same time, the network itself also has a certain degree of elasticity, allowing the material to maintain good elongation at break. At high temperatures, the network can effectively resist deformation, thus exhibiting excellent thermal elongation properties.

[0079] Example 10: Excessive crosslinking accelerator leads to excessively high crosslinking density; the overly dense crosslinking network greatly restricts the movement and extension of molecular chains, making the material hard and brittle; therefore, although the tensile strength reaches the highest level and the thermal elongation performance is the best (almost no deformation), its elongation at break decreases sharply, the material loses its toughness, and it is prone to cracking in actual bending applications.

[0080] Based on the above measurements, Example 6 is selected as the optimal example.

[0081] Comparative Example 1: The difference between this example and Example 6 is that no polyisobutylene-grafted cage-type polysilsesquioxane composite was added.

[0082] Comparative Example 2: The difference between this example and Example 6 is that polyisobutylene and vinyl isobutylated cage-like silsesquioxane are physically mixed.

[0083] Comparative Example 3: The difference between this example and Example 6 is that bis(2-mercaptoethyl) sulfone disulfide was not added.

[0084] Table 3 Performance data of polyisobutylene high-strength wires and cables

[0085] Tensile strength Elongation at break Elongation under load Permanent deformation rate Example 6 30.2MPa 280% 85% 5% Comparative Example 1 18.5MPa 350% 180% 22% Comparative Example 2 22.0MPa 250% 110% 12% Comparative Example 3 25.8MPa 320% 155% 18%

[0086] Comparative Example 1 exhibits significantly reduced thermal elongation properties and the lowest tensile strength.

[0087] Due to the lack of rigidity enhancement and thermal stabilization of the cross-linked network in the polyisobutylene-grafted cage-type polysilsesquioxane composite, the material softens and flows rapidly under high-temperature testing and cannot maintain its shape.

[0088] Although the elongation at break of Example 6 was lower than that of Comparative Example 1, the decrease was much smaller than the increase in tensile strength; however, the overall performance (strength × toughness) of the material in Example 6 was improved, and the thermal elongation performance was significantly improved.

[0089] The tensile strength of Comparative Example 2 was significantly lower than that of Example 6, and its thermal elongation performance (permanent deformation rate of 12%) was much worse than that of Example 6 (5%).

[0090] Physically blended polyisobutylene-grafted cage-type polysilsesquioxane composites lack strong chemical bonds with the polyisobutylene matrix, resulting in weak interfacial bonding. Under stress or heat, stress cannot be effectively transferred, and the interface is prone to debonding, becoming a crack initiation point. Therefore, both strength and resistance to deformation are significantly reduced.

[0091] Comparative Example 3's thermal elongation performance was severely substandard (load elongation 155%, permanent deformation 18%), although its tensile strength and elongation at break were acceptable.

[0092] In the absence of crosslinking accelerators, although the polyisobutylene-grafted cage-type polysilsesquioxane composite grafted composite provides a certain degree of rigidity reinforcement, the polymer molecular chains fail to form a stable three-dimensional network. Under high temperature and load, relative slippage between molecular chains is prone to occur, leading to excessive and irreversible deformation.

[0093] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength polyisobutylene wire and cable, characterized in that, The device includes a conductor, an insulating layer, and a protective sleeve. The protective sleeve comprises the following raw materials: 70-85 parts by weight of polyisobutylene, 5-8 parts by weight of maleic anhydride-grafted polypropylene, 3-5 parts by weight of nanofiller, 4-6 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite, 5-10 parts by weight of resorcinol bis(diphenyl phosphate), and 0.3-0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol, and 1.0-2.5% by weight of bis(2-mercaptoethyl) sulfone disulfide. The polyisobutylene-grafted cage-type polysilsesquioxane composite is prepared by covalent grafting of polyisobutylene and vinyl isobutylated cage-type polysilsesquioxane via free radical reaction; the mass ratio of polyisobutylene to vinyl isobutylated cage-type polysilsesquioxane is 100:2-4.

2. The polyisobutylene high-strength wire and cable according to claim 1, characterized in that, The preparation method of the polyisobutylene-grafted cage-type polysilsesquioxane composite is as follows: Under a nitrogen atmosphere, polyisobutylene and vinyl isobutylated cage-type polysilsesquioxane are mixed and then melt-dispersed in a twin-screw extruder at a barrel temperature of 170-200℃ and a screw speed of 200-300 rpm. Di-tert-butyl peroxide is then added, and the reaction continues for 5-10 minutes to obtain the final material. After the reaction, the material is extruded into a circulating water cooling tank at a temperature of 10-40℃ for solidification. It is then granulated using a pelletizer to obtain pellets with a length of 2-5 mm. The pellets are then heat-treated at 120-160℃ for 5-10 minutes to obtain the polyisobutylene-grafted cage-type polysilsesquioxane composite.

3. The polyisobutylene high-strength wire and cable according to claim 2, characterized in that, The amount of di-tert-butyl peroxide added is 0.1-0.3% of the mass of polyisobutylene.

4. A method for preparing polyisobutylene high-strength wires and cables, used to prepare polyisobutylene high-strength wires and cables as described in any one of claims 1-3, characterized in that, The preparation method of the polyisobutylene high-strength wire and cable is as follows: S1.1 Polyethylene containing 2.5% dicumyl peroxide is extruded and coated onto tin-plated copper wire at 130-150℃ to obtain an uncrosslinked insulation layer; then it is treated in a nitrogen atmosphere at a pressure of 0.6-1.2MPa and a temperature of 180-200℃ for 10-20 minutes, and finally cooled and shaped to obtain a crosslinked polyethylene insulation layer. S1.2, 70-85 parts by weight of polyisobutylene, 5-8 parts by weight of maleic anhydride-grafted polypropylene, 3-5 parts by weight of nanofiller, 4-6 parts by weight of polyisobutylene-grafted cage-type polysilsesquioxane composite, 5-10 parts by weight of resorcinol bis(diphenyl phosphate) and 0.3-0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol are added to a high-speed mixer and melt-blended under nitrogen protection at 170-190°C to obtain a molten material; the bis(2-mercaptoethyl) sulfone disulfide is added in the last 2 minutes of melt blending. S1.

3. The molten material is passed through the die of an extruder and the outer sheath is extruded and coated onto the insulation layer at 170-190℃. After extrusion, the material is cooled and shaped in a water bath to obtain a cable semi-finished product. Subsequently, the cable semi-finished product is heat-treated, and finally cooled, drawn and wound to obtain a polyisobutylene high-strength wire and cable.

5. The method for preparing polyisobutylene high-strength wires and cables according to claim 4, characterized in that, In S1.2, the preparation method of the nanofiller is as follows: nano-silica is dispersed in ethanol at 60℃ at a mass ratio of 1:20, and 5-15% of methacryloyloxypropyltrimethoxysilane is added, and the reaction is carried out for 4-6 hours. After the reaction is completed, the nanofiller is filtered, washed, and then dried at -0.08MPa and 80-120℃ for 3-5 hours to obtain the nanofiller.

6. The method for preparing polyisobutylene high-strength wires and cables according to claim 4, characterized in that, In S1.3, the screw speed of the extruder for extruding the coating is 80-120 rpm, the extrusion speed is 2-6 m / min, and the molding pressure is 20-50 bar.

7. The method for preparing polyisobutylene high-strength wires and cables according to claim 4, characterized in that, In S1.3, the heat treatment process is carried out under segmented heating conditions: first, preheating at 90-110℃ for 5 minutes, and then heating to 120-130℃ for 10-15 minutes.