High-performance insulating compression-resistant cable protection sleeve

Abstract

The invention discloses a high-performance insulating compression-resistant cable protection sleeve, and relates to the technical field of cable sleeve preparation, and the high-performance insulating compression-resistant cable protection sleeve specifically comprises the following steps: mixing epoxy resin and surface-treated zinc oxide whiskers to form basic slurry; through centrifugal classification, the slurry forms a gradient prefabricated body with the whisker concentration gradually increased from inside to outside in the mold; injecting a resin liquid containing a curing agent under an orthogonal magnetic field, so that the whiskers are radially and directionally arranged and pre-cured; applying axial high pressure and high temperature to the semi-cured sleeve to complete the complete curing of the resin; the inner wall is subjected to finish turning after demolding, and surface sand blasting treatment is conducted; dip-coating a nano aluminum oxide dispersion liquid, and drying to form an insulating layer; and cooling to obtain the insulating compression-resistant sleeve with the gradient reinforcing structure. According to the preparation method, a radial ordered reinforced structure can be constructed in an epoxy resin matrix and a continuous density gradient can be formed through a magnetic field-assisted directionally-arranged zinc oxide whisker and a gradient centrifugal forming technology.

Description

Technical Field

[0001] This invention belongs to the field of cable sleeve manufacturing technology, and in particular relates to a high-performance insulated and pressure-resistant cable protection sleeve. Background Technology

[0002] Cable protection sleeves are tubular protective structures used to wrap power or communication cables. They are typically made of high-polymer composite materials, and their core function is to provide mechanical compression protection and reliable electrical insulation for cables in complex environments. Specifically, the sleeve uses a multi-layered composite design to resist external impacts, soil corrosion, and moisture penetration, while relying on high-dielectric-strength materials (such as modified epoxy resin and nano-ceramic coatings) to block current leakage, ensuring the long-term safe operation of cables under harsh conditions such as high-voltage power transmission, rail transportation, and submarine laying.

[0003] In the field of high-voltage cable protection bushings, traditional reinforcement structures (such as randomly dispersed fillers or unidirectional fiber laminations) have limitations. Unidirectional reinforcement cannot synergistically optimize axial and radial mechanical properties; randomly dispersed reinforcement phases are prone to local stress concentration under pressure, leading to the initiation of microcracks; while unidirectional reinforcement improves axial strength, it is prone to interlaminar delamination or buckling failure under lateral loads due to the lack of radial support; especially for working conditions that need to withstand axial pressure and radial extrusion stress simultaneously, existing structures are difficult to achieve a balanced match between compressive strength and deformation capacity. To address these issues, the following solutions are proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a high-performance insulating and pressure-resistant cable protection sleeve. By using magnetic field-assisted directional zinc oxide whiskers and gradient centrifugal molding technology, a radially ordered reinforcement structure and a continuous density gradient can be constructed in an epoxy resin matrix. This solves the problem that the axial compressive strength and radial deformation capacity cannot be optimized in a coordinated manner due to the single-direction reinforcement in existing cable protection sleeves.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions: The present invention is a high-performance insulating and pressure-resistant cable protective sleeve, which comprises the following components by weight: 100 parts epoxy resin, 12-18 parts zinc oxide whiskers, 1%-2% silane coupling agent by weight of whiskers, 4-6 parts methyltetrahydrophthalic anhydride, 50-60 parts acetone and 3-5 parts nano alumina.

[0006] Furthermore, the method for preparing the protective sleeve includes the following steps: Step S1, Raw material pretreatment: Mix epoxy resin with surface-treated zinc oxide whiskers to form a base slurry; Step S2, Gradient Structure Preconstruction: Through centrifugal classification, the slurry is made into a gradient preform in the mold with the whisker concentration increasing from the inside to the outside; Step S3, Magnetic field directional curing: Resin liquid containing curing agent is injected under an orthogonal magnetic field to make the whiskers radially oriented and pre-cured; Step S4, High-pressure densification: Apply axial high pressure and high temperature to the semi-cured sleeve to complete the resin curing; Step S5, Demolding and Finishing: After demolding, the inner wall is precision machined to a tolerance of ±0.1mm, and the surface is sandblasted. Step S6, Insulation Strengthening Treatment: Dip-coat with nano-alumina dispersion and dry to form an insulation layer; Step S7: Obtain the finished bushing: After cooling, an insulating and pressure-resistant bushing with a gradient reinforcement structure is obtained.

[0007] Further, step S1, the raw material pretreatment, specifically includes the following steps: Step S11: Weigh 100 parts by weight of E-51 type epoxy resin and place it in a vacuum planetary mixer; Step S12: Add 15 parts by weight of zinc oxide whiskers that have been surface-treated with silane coupling agent KH-550. The whisker specifications are 20 μm in length and 0.5 μm in diameter. Step S13: Start the agitator and mix continuously at 400 rpm for 10 minutes to form a uniformly dispersed resin whisker base slurry; This step modifies the surface of zinc oxide whiskers with a silane coupling agent to enhance their interfacial bonding with epoxy resin, while simultaneously forming a uniform slurry through preliminary mixing, laying the foundation for gradient construction.

[0008] Furthermore, step S2, the gradient structure preconstruction, specifically includes the following steps: Step S21: Transfer the mixed slurry to a centrifuge mold, which is preheated to 60°C; Step S22: Turn on the centrifuge. In the first stage, rotate at 200 rpm for 5 minutes. In the second stage, increase to 800 rpm and rotate for 8 minutes. Use the centrifugal force difference to make the zinc oxide whiskers separate into layers according to density. Step S23: Turn off the centrifuge, and a gradient preform with increasing whisker concentration from the inside to the outside is formed in the mold; This step utilizes the principle of differential sedimentation due to centrifugal force to create a gradient distribution of zinc oxide whiskers with increasing concentration from the inside to the outside within the mold, thus prefabricating a non-uniform reinforced structure to optimize mechanical load-bearing performance.

[0009] Furthermore, step S3, magnetic field-oriented curing, specifically includes the following steps: Step S31: Place the centrifugal mold in an orthogonal magnetic field device with a magnetic field strength of 0.5T in each of the X and Y directions; Step S32: Inject an epoxy resin diluent containing 5 parts by weight of methyltetrahydrophthalic anhydride curing agent, wherein the epoxy resin to acetone ratio in the diluent is 1:1; Step S33: Activate the magnetic field device and maintain it for 30 minutes to allow the whiskers to align radially; Step S34: Increase the temperature to 80℃ at a rate of 2℃ / min and hold for 1 hour to complete the pre-curing; This step forces the whiskers to align radially using an orthogonal magnetic field, while low-temperature pre-curing locks in this orientation structure, achieving multidimensional reinforcement.

[0010] Furthermore, step S4, high-pressure densification, specifically includes the following steps: Step S41: Transfer the semi-cured sleeve into the autoclave; Step S42: Apply an axial pressure of 15 MPa while simultaneously increasing the temperature to 150 °C at a rate of 0.5 °C / min; Step S43: Hold the pressure and heat for 2 hours to allow the resin to fully cure; This step compresses the resin molecular chains under high temperature and pressure, eliminates internal pores and increases crystallinity, making the gradient reinforcement structure completely dense with the matrix, and obtaining ultra-high axial compressive strength.

[0011] Furthermore, step S5, the demolding and finishing process, specifically includes the following steps: Step S51: After cooling to 60℃, release the pressure, disassemble the mold and remove the sleeve blank; Step S52: Use a lathe to cut the inner wall to the target size; Step S53: In the sandblasting chamber, the outer surface of the casing is uniformly sandblasted with 120-mesh quartz sand at a pressure of 0.4 MPa to form a matte protective layer with anti-glare effect. This step ensures the dimensional accuracy of the sleeve through machining, and sandblasting increases the surface roughness to improve the adhesion of subsequent coatings, while also forming a scratch-resistant protective layer.

[0012] Furthermore, step S6, the insulation strengthening treatment, specifically includes the following steps: Step S61: Completely immerse the sleeve in the nano alumina dispersion, which is prepared by mixing alumina particles with a particle size of 50 nanometers with deionized water, with the solid content strictly controlled at 30%, and ensure that the immersion time reaches 30 seconds to fully wet the surface. Step S62: Vertically lift the sleeve at a constant speed of 10 cm per minute to allow excess liquid to flow down evenly and form a wet coating on the outer surface of the sleeve; Step S63: Transfer the sleeve to a circulating hot air oven preheated to 120 degrees Celsius and keep it for 30 minutes to allow the coating to dry and cure completely, forming a dense insulating layer; This step fills surface micro-defects with a nano-alumina coating, forming a through-hole insulating network with the internal whiskers, synergistically improving the overall dielectric strength and arc resistance of the bushing.

[0013] The present invention has the following beneficial effects: 1. This invention controls the radial orientation of zinc oxide whiskers in an epoxy resin matrix using an orthogonal magnetic field, avoiding the limitations of random dispersion or unidirectional lamination reinforcement. The whiskers form a radially ordered structure along the radial direction of the sleeve, enabling the material to uniformly distribute stress across the entire cross-section through the oriented arrangement of the whiskers when subjected to axial pressure. Simultaneously, the gradient centrifugation process continuously increases the whisker concentration from the inner layer to the outer layer, forming a density gradient that matches the stress distribution. This synergistic effect improves the axial compressive strength and deformation resistance of the sleeve, and avoids the problem of local stress concentration caused by uneven distribution of the reinforcing phase.

[0014] 2. The centrifugal magnetic field process of this invention constructs an outer rigid and inner tough gradient structure; the outer high-density whisker region provides rigid support and effectively resists external extrusion; the lower whisker concentration in the inner layer retains the elasticity of the resin matrix and avoids brittle fracture of the sleeve due to excessive rigidity; this structure allows the sleeve to buffer stress transmission through the gradient transition layer when subjected to dynamic loads, reducing the risk of interface peeling; this design achieves synergistic optimization of compressive strength and elastic modulus, and is suitable for working conditions that require simultaneous impact resistance and fatigue resistance.

[0015] 3. The nano-alumina coating and whisker reinforcement of this invention form a double insulation barrier; the oriented zinc oxide whiskers construct a through-type thermally conductive / insulating network in the matrix, accelerating local heat diffusion; the dense nano-coating on the surface fills microscopic defects and blocks surface discharge channels; the synergistic effect of the two can improve the volume resistivity and surface arc resistance, and inhibit the growth of electrical trees; this structure can still maintain insulation integrity under mechanical stress, and is especially suitable for cable protection in long-term operation under high voltage environment.

[0016] 4. The present invention implements magnetic field orientation and centrifugal gradient prefabrication in stages to avoid performance fluctuations caused by filler sedimentation or agglomeration during blending; firstly, the whisker distribution is initially stabilized by centrifugal force, and then the orientation is precisely adjusted in the magnetic field to ensure that the spatial position of the reinforcing phase is controllable; the high-pressure curing stage further eliminates porosity and improves the interfacial bonding strength; the process parameters are adjustable, which solves the common batch consistency problem of complex structure composite materials and meets the requirements of yield rate for industrial production.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the manufacturing process of a high-performance insulating and pressure-resistant cable protection sleeve according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention relates to a high-performance insulating and pressure-resistant cable protective sleeve, which comprises the following components by weight: 100 parts epoxy resin, 12–18 parts zinc oxide whiskers, 1%–2% silane coupling agent by weight of whiskers, 4–6 parts methyltetrahydrophthalic anhydride, 50–60 parts acetone, and 3–5 parts nano-alumina.

[0022] Please see Figure 1 As shown, the preparation method of the protective sleeve includes the following steps: Step S1, Raw material pretreatment: Mix epoxy resin with surface-treated zinc oxide whiskers to form a base slurry; Step S1, raw material pretreatment specifically includes the following steps: Step S11: Weigh 100 parts by weight of E-51 type epoxy resin and place it in a vacuum planetary mixer; Step S12: Add 15 parts by weight of zinc oxide whiskers that have been surface-treated with silane coupling agent KH-550. The whisker specifications are 20 μm in length and 0.5 μm in diameter. Step S13: Start the agitator and mix continuously at 400 rpm for 10 minutes to form a uniformly dispersed resin whisker base slurry.

[0023] Step S2, Gradient Structure Preconstruction: Through centrifugal classification, the slurry is made into a gradient preform in the mold with the whisker concentration increasing from the inside to the outside; Step S2, gradient structure preconstruction, specifically includes the following steps: Step S21: Transfer the mixed slurry to a centrifuge mold, which is preheated to 60°C; Step S22: Turn on the centrifuge. In the first stage, rotate at 200 rpm for 5 minutes. In the second stage, increase to 800 rpm and rotate for 8 minutes. Use the centrifugal force difference to make the zinc oxide whiskers separate into layers according to density. Step S23: Turn off the centrifuge, and a gradient preform with increasing whisker concentration is formed inside the mold.

[0024] Step S3, Magnetic field directional curing: Resin liquid containing curing agent is injected under an orthogonal magnetic field to make the whiskers radially oriented and pre-cured; Step S3, magnetic field directional curing, specifically includes the following steps: Step S31: Place the centrifugal mold in an orthogonal magnetic field device with a magnetic field strength of 0.5T in each of the X and Y directions; Step S32: Inject an epoxy resin diluent containing 5 parts by weight of methyltetrahydrophthalic anhydride curing agent, wherein the epoxy resin to acetone ratio in the diluent is 1:1; Step S33: Activate the magnetic field device and maintain it for 30 minutes to allow the whiskers to align radially; Step S34: Heat to 80°C at a rate of 2°C / min and hold for 1 hour to complete pre-curing.

[0025] Step S4, High-pressure densification: Apply axial high pressure and high temperature to the semi-cured sleeve to complete the resin curing; Step S4, high-pressure densification specifically includes the following steps: Step S41: Transfer the semi-cured sleeve into the autoclave; Step S42: Apply an axial pressure of 15 MPa while simultaneously increasing the temperature to 150 °C at a rate of 0.5 °C / min; Step S43: Hold pressure and heat for 2 hours to allow the resin to fully cure.

[0026] Step S5, Demolding and Finishing: After demolding, the inner wall is precision machined to a tolerance of ±0.1mm, and the surface is sandblasted. Step S5, demolding and finishing, specifically includes the following steps: Step S51: After cooling to 60℃, release the pressure, disassemble the mold and remove the sleeve blank; Step S52: Use a lathe to cut the inner wall to the target size; Step S53: In the sandblasting chamber, the outer surface of the casing is uniformly sandblasted with 120-mesh quartz sand at a pressure of 0.4 MPa to form a matte protective layer with anti-glare effect.

[0027] Step S6, Insulation Strengthening Treatment: Dip-coat with nano-alumina dispersion and dry to form an insulation layer; Step S6, the insulation strengthening treatment specifically includes the following steps: Step S61: Completely immerse the sleeve in the nano alumina dispersion, which is prepared by mixing alumina particles with a particle size of 50 nanometers with deionized water, with the solid content strictly controlled at 30%, and ensure that the immersion time reaches 30 seconds to fully wet the surface. Step S62: Vertically lift the sleeve at a constant speed of 10 cm per minute to allow excess liquid to flow down evenly and form a wet coating on the outer surface of the sleeve; Step S63: Transfer the sleeve to a circulating hot air oven preheated to 120 degrees Celsius and keep it for 30 minutes to allow the coating to dry and cure completely, forming a dense insulating layer.

[0028] Step S7: Obtain the finished bushing: After cooling, an insulating and pressure-resistant bushing with a gradient reinforcement structure is obtained.

[0029] One specific application of this embodiment is: Preparation of DN100 cable protection sleeve The raw material proportions are shown in the table below (parts by weight): Components Dosage Specifications Epoxy resin 100 Type E-51, epoxy value 0.51 Zinc oxide whiskers 15 40:1 aspect ratio, KH-550 modified Methyltetrahydrophthalic anhydride curing agent 5 Active hydrogen equivalent 165 Nano alumina dispersion — Solid content 30%, pH=6.8 Implementation steps: Step S1: Preparation of mixed slurry Add 100 kg of epoxy resin to a vacuum planetary mixer; add 15 kg of zinc oxide whiskers treated with KH-550 in batches (add in 3 batches, with an interval of 2 minutes between each batch); stir at 400 rpm for 10 minutes and degas at a vacuum degree of -0.08 MPa.

[0030] Step S2, Centrifugal Gradient Molding Pour the slurry into a centrifuge mold preheated to 60°C (mold size: Φ105mm×1000mm); start the centrifuge: first stage 200rpm×5min → second stage 800rpm×8min; after stopping the machine, a distinct gradient layer is formed inside the mold (inner layer whisker density 18wt%, outer layer 32wt%).

[0031] Step S3: Magnetic field directional curing Place the mold into an orthogonal magnetic field device (X / Y electromagnets, 150mm apart); inject an epoxy resin-acetone mixture containing 5kg of curing agent (1:1 mass ratio); turn on the 0.5T magnetic field and let it stand for 30 minutes to allow the whiskers to align radially (whisker deflection angle > 85°); program the temperature rise: 20℃→80℃ (2℃ / min), and hold for 1 hour for pre-curing.

[0032] Step S4: High-pressure curing and shaping The semi-cured sleeve is moved into the autoclave and fitted with the mandrel (Φ98mm); axial pressure of 15MPa is applied, and the temperature is raised simultaneously: 80℃→150℃ (0.5℃ / min); pressure is maintained at 150℃ for 2 hours, and the resin is completely cured (gel rate>98%).

[0033] Step S5: Machining Cool down to 60℃ to release pressure, demold and remove the sleeve blank; finish machine the inner hole to Φ100±0.1mm on a lathe; surface sandblasting: 120 mesh quartz sand, 0.4MPa air pressure, moving speed 10cm / s.

[0034] Step S6: Preparation of insulating coating The sleeve was immersed in a nano-alumina dispersion (25℃) for 3 min; the lifting speed was 10 cm / min, and the wet film thickness was 50 μm; it was cured in a 120℃ oven for 30 min to form a dense coating of 5 μm.

[0035] Step S7: Obtaining the finished product The cable protection sleeve (DN100×1000mm, wall thickness 2.5mm) was obtained by cooling at room temperature.

[0036] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-performance insulating and pressure-resistant cable protection sleeve, characterized in that, The protective sleeve comprises, by weight, the following components: 100 parts epoxy resin, 12–18 parts zinc oxide whiskers, 1%–2% silane coupling agent by weight of whiskers, 4–6 parts methyltetrahydrophthalic anhydride, 50–60 parts acetone, and 3–5 parts nano-alumina.

2. The high-performance insulated and pressure-resistant cable protection sleeve according to claim 1, characterized in that, The method for preparing the protective sleeve includes the following steps: Step S1, Raw material pretreatment: Mix epoxy resin with surface-treated zinc oxide whiskers to form a base slurry; Step S2, Gradient Structure Preconstruction: Through centrifugal classification, the slurry is made into a gradient preform in the mold with the whisker concentration increasing from the inside to the outside; Step S3, Magnetic field directional curing: Resin liquid containing curing agent is injected under an orthogonal magnetic field to make the whiskers radially oriented and pre-cured; Step S4, High-pressure densification: Apply axial high pressure and high temperature to the semi-cured sleeve to complete the resin curing; Step S5, Demolding and Finishing: After demolding, the inner wall is precision machined to a tolerance of ±0.1mm, and the surface is sandblasted. Step S6, Insulation Strengthening Treatment: Dip-coat with nano-alumina dispersion and dry to form an insulation layer; Step S7: Obtain the finished bushing: After cooling, an insulating and pressure-resistant bushing with a gradient reinforcement structure is obtained.

3. The high-performance insulated and pressure-resistant cable protection sleeve according to claim 2, characterized in that, Step S1, the raw material pretreatment, specifically includes the following steps: Step S11: Weigh 100 parts by weight of E-51 type epoxy resin and place it in a vacuum planetary mixer; Step S12: Add 15 parts by weight of zinc oxide whiskers that have been surface-treated with silane coupling agent KH-550. The whisker specifications are 20 μm in length and 0.5 μm in diameter. Step S13: Start the agitator and mix continuously at 400 rpm for 10 minutes to form a uniformly dispersed resin whisker base slurry.

4. The high-performance insulating and pressure-resistant cable protection sleeve according to claim 2, characterized in that, Step S2, the gradient structure preconstruction, specifically includes the following steps: Step S21: Transfer the mixed slurry to a centrifuge mold, which is preheated to 60°C; Step S22: Turn on the centrifuge. In the first stage, rotate at 200 rpm for 5 minutes. In the second stage, increase to 800 rpm and rotate for 8 minutes. Use the centrifugal force difference to make the zinc oxide whiskers separate into layers according to density. Step S23: Turn off the centrifuge, and a gradient preform with increasing whisker concentration is formed inside the mold.

5. A high-performance insulating and pressure-resistant cable protection sleeve according to claim 2, characterized in that, Step S3, magnetic field-oriented curing, specifically includes the following steps: Step S31: Place the centrifugal mold in an orthogonal magnetic field device with a magnetic field strength of 0.5T in each of the X and Y directions; Step S32: Inject an epoxy resin diluent containing 5 parts by weight of methyltetrahydrophthalic anhydride curing agent, wherein the epoxy resin to acetone ratio in the diluent is 1:1; Step S33: Activate the magnetic field device and maintain it for 30 minutes to allow the whiskers to align radially; Step S34: Heat to 80°C at a rate of 2°C / min and hold for 1 hour to complete pre-curing.

6. A high-performance insulating and pressure-resistant cable protection sleeve according to claim 2, characterized in that, Step S4, high-pressure densification, specifically includes the following steps: Step S41: Transfer the semi-cured sleeve into the autoclave; Step S42: Apply an axial pressure of 15 MPa while simultaneously increasing the temperature to 150 °C at a rate of 0.5 °C / min; Step S43: Hold pressure and heat for 2 hours to allow the resin to fully cure.

7. A high-performance insulating and pressure-resistant cable protection sleeve according to claim 2, characterized in that, Step S5, demolding and finishing, specifically includes the following steps: Step S51: After cooling to 60℃, release the pressure, disassemble the mold and remove the sleeve blank; Step S52: Use a lathe to cut the inner wall to the target size; Step S53: In the sandblasting chamber, the outer surface of the casing is uniformly sandblasted with 120-mesh quartz sand at a pressure of 0.4 MPa to form a matte protective layer with anti-glare effect.

8. A high-performance insulating and pressure-resistant cable protection sleeve according to claim 2, characterized in that, Step S6, the insulation strengthening treatment, specifically includes the following steps: Step S61: Completely immerse the sleeve in the nano alumina dispersion, which is prepared by mixing alumina particles with a particle size of 50 nanometers with deionized water, with the solid content strictly controlled at 30%, and ensure that the immersion time reaches 30 seconds to fully wet the surface. Step S62: Vertically lift the sleeve at a constant speed of 10 cm per minute to allow excess liquid to flow down evenly and form a wet coating on the outer surface of the sleeve; Step S63: Transfer the sleeve to a circulating hot air oven preheated to 120 degrees Celsius and keep it for 30 minutes to allow the coating to dry and cure completely, forming a dense insulating layer.

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