High-elasticity waterproof cable based on blending of water-blocking powder and elastomer

Abstract

The invention relates to the technical field of electric wires and cables, discloses a high-elasticity waterproof cable based on blending of water-blocking powder and an elastomer, and aims to solve the problems that in the prior art, during long-term dynamic service, interlayer separation is easily caused by interfacial stress superposition, so that elasticity attenuation and waterproof barrier damage are caused, and the service life is affected. According to the invention, the sodium polyacrylate water-blocking powder is subjected to composite modification and is blended with an elastomer matrix, modified nano silicon dioxide is matched for dispersion, an inner and outer layer gradient insulation structure is designed, and ultrasonic dispersion, nitrogen protection steam cross-linking and other processes are combined; the cable is sequentially provided with the conductor layer, the conductor shielding layer, the gradient insulation layer, the insulation shielding layer and the sheath layer from inside to outside, interface stress concentration is reduced, interlayer combination stability is enhanced, and the cable can still keep excellent elastic recovery capability and waterproof barrier integrity under high-frequency torsion and repeated dry-wet cycles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric wire and cable, and particularly relates to a high-elasticity waterproof cable based on water-blocking powder and elastomer blending. BACKGROUND

[0002] High-elasticity waterproof cable is a kind of special cable with excellent deformation recovery ability and water blocking performance, which is widely used in building expansion joints, industrial automation robots, new energy wind power equipment and other scenes. For example, in building expansion joints, the cable needs to withstand the stretching and bending caused by structural settlement; the joint cable of industrial robots needs to adapt to high-frequency twisting, and these scenes often accompany with humid environment. Therefore, the cable needs to have high elasticity to cope with dynamic deformation and long-term waterproof to avoid insulation failure caused by water intrusion. In order to achieve these performances, the industry usually selects ethylene propylene diene rubber (EPDM) and thermoplastic elastomer (TPE) as the elastic base material to ensure the deformation recovery by the flexibility of the molecular chain; and uses acrylic salt and starch grafted water-blocking powder to block water penetration by its water absorption and expansion characteristics.

[0003] The prior art improves the performance by optimizing the cable layer structure or improving the water-blocking material composition. For example, a high-molecular waterproof cable with the publication number CN115064310A sets an elastic inner layer and an outer layer, a toughness fiber and a composite waterproof layer containing water-blocking powder, and is matched with a shielding layer, a sheath and other structures to improve the waterproof effect by using the expansion characteristics of the water-blocking powder and the structural support; a compression-resistant water-blocking layer and an insulated cable with the layer with the publication number CN120221179A uses a water-blocking cloth wrapped with a water-blocking powder containing vinyl benzene sulfonate-acrylic salt crosslinked copolymer to form a compression-resistant water-blocking layer, and combines the overall structure design of the conductor and the insulation layer to enhance the water absorption and expansion ability of the water-blocking layer and the compression resistance reliability in water environment; a low-voltage waterproof cable with the publication number CN209418183U sets a thermoplastic elastomer water-blocking layer with electrostatic spraying water-blocking powder in the protective layer, and the outer sheath is additionally provided with a steel wire and is matched with a loose sleeve and a shielding tube to simultaneously improve the waterproof performance and mechanical strength and reduce the damage risk.

[0004] However, the existing high-elasticity waterproof cable generally adopts a structure scheme of layered arrangement of the elastomer functional layer and the waterproof layer of water-blocking powder, and this structure has a performance failure chain problem that is difficult to avoid in the long-term dynamic service. On the one hand, the water-blocking powder in the waterproof layer will swell repeatedly with water absorption and shrink with water loss in the environmental dry-wet cycle, and this process will generate local radial concentrated stress at the interface between the elastomer layer and the waterproof layer; on the other hand, the dynamic deformation rate of the elastomer layer is significantly different from that of the waterproof layer, and in the long-term cyclic deformation, a continuous shear stress will be formed at the interface. After the superposition of the two stresses, the interface bonding force between the elastomer layer and the waterproof layer will continuously attenuate, and then the interface peeling strength will continuously decrease, and finally the continuous interlayer separation will be caused, which will not only weaken the elastic recovery ability of the cable, but also damage the waterproof barrier, and seriously shorten the service life of the cable. SUMMARY

[0005] The technical problem to be solved by the present application is that the functional layer is prone to interlayer separation in the prior art, and therefore a high-elasticity waterproof cable based on blending of water-blocking powder and elastomer is proposed.

[0006] In order to achieve the above-mentioned purpose, the following technical scheme is adopted in the present application: a high-elasticity waterproof cable based on blending of water-blocking powder and elastomer, which comprises, from inside to outside, a conductor layer, a conductor shielding layer, an insulation layer, an insulation shielding layer and a sheath layer, the insulation layer is a composite structure of inner and outer layers, the insulation layer comprises an insulation inner layer and an insulation outer layer distributed along the radial direction of the cable, the insulation inner layer is a pure elastomer transition layer, and the insulation outer layer is a blending layer of modified water-blocking powder and elastomer matrix.

[0007] Preferably, the composition of the insulation outer layer comprises, by weight, 15-20 parts of modified water-blocking powder, 70-80 parts of elastomer matrix, 0.5-1.0 parts of crosslinking regulator, 1.0-1.5 parts of dispersing aid, 1-2 parts of softening agent, 1.5-2.0 parts of crosslinking agent and 0.5-1.0 parts of composite antioxidant, the crosslinking regulator is triallyl isocyanurate, the softening agent is liquid paraffin, and the crosslinking agent is dicumyl peroxide.

[0008] Preferably, the modified water-blocking powder comprises a water-blocking powder base material and a composite modifier, the water-blocking powder base material is sodium polyacrylate, the mass fraction of sodium polyacrylate in the total mass of the modified water-blocking powder is 90-95%, and the composite modifier accounts for 5-10% of the total mass of the modified water-blocking powder, which is used to improve the compatibility of sodium polyacrylate and the elastomer matrix.

[0009] Preferably, the composite modifier is a mixture of silane coupling agent KH-550 and polyether modified silicone oil, and the mass ratio of silane coupling agent KH-550 to polyether modified silicone oil is 3:7-6:4, the silane coupling agent KH-550 is used for condensation reaction with the hydroxyl group of sodium polyacrylate to realize chemical anchoring, and the polyether modified silicone oil is used to improve the entangled compatibility with the elastomer matrix.

[0010] Preferably, the elastomer matrix comprises a main elastomer and an auxiliary elastomer, the main elastomer is ethylene-propylene-diene rubber, accounting for 90-95% of the total mass of the elastomer matrix, and the auxiliary elastomer is ethylene-octene copolymer, accounting for 5-10% of the total mass of the elastomer matrix.

[0011] Preferably, the dispersing aid is nano-silica modified by silane coupling agent KH-570, and the amount of silane coupling agent KH-570 is 5% of the mass of nano-silica.

[0012] Preferably, the composite antioxidant is composed of 2,6-di-tert-butyl-p-cresol and antioxidant 1010 at a mass ratio of 1:1.

[0013] Preferably, the composition of the insulating inner layer includes, by weight: 75 parts of ethylene-propylene-diene rubber, 1.8 parts of dicumyl peroxide, 0.6 parts of composite antioxidant, and 2.5 parts of blended particles, which are elastomer and modified water-blocking powder blended particles, and the raw materials for preparing the blended particles include an elastomer matrix, modified water-blocking powder, a dispersing aid, and a crosslinking regulator, which are used to improve the interfacial compatibility of the insulating inner layer and the insulating outer layer, and the content of modified water-blocking powder in the insulating inner layer is much lower than that in the insulating outer layer.

[0014] Preferably, when the cable core is formed by twisting a plurality of conductors, the insulating shielding layer and the sheath layer further comprise a filling layer and a wrapping layer.

[0015] Preferably, the preparation steps of the insulating layer include: S1: drying sodium polyacrylate at 105℃ and -0.09MPa for 4h, then mixing it with the composite modifier diluted with 3 times of anhydrous ethanol under nitrogen protection at 100℃, and adding modified nano-silica and stirring uniformly, and then cooling to obtain modified water-blocking powder; S2: starting the double-screw extruder, controlling the temperature of the homogenizing section at 110℃, first adding ethylene-propylene-diene rubber, ethylene-octene copolymer, triallyl isocyanurate, and liquid paraffin for melt mixing, then adding modified water-blocking powder, and after mixing, turning on the ultrasonic dispersion, extruding and pelletizing, and drying at 80℃ for 2h to obtain blended particles; S3: adding ethylene-propylene-diene rubber, dicumyl peroxide, composite antioxidant, and blended particles into the double-screw extruder, melt mixing, and then extruding and pelletizing as the insulating inner layer material; S4: starting the double-layer co-extruder head, feeding the insulating inner layer material and the insulating outer layer blended particles into the inner and outer layer runners respectively, and synchronously extruding and coating outside the conductor shielding layer; S5: feeding the extruded wire core into a nitrogen-protected steam crosslinking pipe, controlling the volume ratio of nitrogen and steam at 3:7 at 170℃ and 0.8MPa, crosslinking for 18min, then gradient water cooling, and finally vacuum drying at 60℃ and -0.08MPa for 1h to form the insulating layer.

[0016] The technical effects and advantages of this invention are as follows: In this invention, high elasticity and long-lasting waterproofing are achieved simultaneously through the synergistic blending of modified water-blocking powder and elastomer matrix. The modified water-blocking powder first undergoes a condensation reaction between the amino group of silane coupling agent KH-550 and the hydroxyl group of sodium polyacrylate. Then, the non-polar segments of polyether-modified silicone oil entangle with the elastomer molecular chains, eliminating the polarity difference between the two. At the same time, the steric hindrance effect of modified nano-silica prevents the agglomeration of sodium polyacrylate particles. The elastomer matrix is ​​mainly composed of EPDM and supplemented by POE. The ratio of the two is optimized to balance the rigidity and flexibility of the materials, forming a complete and continuous elastic phase. This solves the problem of interlayer separation that easily occurs in the long-term dynamic service of existing layered structures, reduces interfacial stress concentration, enhances the stability of interlayer bonding, and enables the cable to maintain excellent elastic recovery ability and waterproof barrier integrity under high-frequency torsion and repeated wet and dry cycles. In this invention, the synergistic combination of a gradient insulation layer and an ultrasonic dispersion process balances structural stability and insulation reliability. The gradient insulation layer uses an inner transition elastomer to achieve a smooth performance transition between the conductor shielding layer and the outer blended water-blocking layer, reducing interfacial shear stress caused by abrupt performance changes. During the preparation of the outer blended water-blocking layer, the ultrasonic dispersion process ensures that the modified water-blocking powder is uniformly distributed in the elastomer matrix, forming a continuous and uninterrupted water-blocking barrier. This avoids the formation of local water-permeable channels and eliminates the need for an additional independent water-blocking layer. This ensures that key insulation properties such as volume resistivity and breakdown field strength meet the safety requirements of low-voltage cables, while also improving the overall mechanical performance consistency of the insulation layer, reducing the accumulation of residual stress during static and dynamic deformation cycles, and lowering the risk of insulation failure. Attached Figure Description

[0017] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0018] Figure 1 This is a schematic diagram of the preparation process of the high-elasticity waterproof cable insulation layer of the present invention; Figure 2 A three-dimensional structural schematic diagram of the highly elastic waterproof cable provided in Example 1 of the present invention; Figure 3 A three-dimensional structural schematic diagram of the cable provided in Example 1 of the present invention from another angle; Figure 4 A three-dimensional structural schematic diagram of the highly elastic waterproof cable provided in Example 2 of the present invention; Figure 5 This is a three-dimensional structural diagram of the cable provided in Example 2 of the present invention from another angle.

[0019] Legend: 1. Conductor layer; 2. Conductor shielding layer; 3. Insulation layer; 4. Insulation shielding layer; 5. Sheath layer; 6. Insulation inner layer; 7. Insulation outer layer; 8. Filler layer; 9. Wrapping tape layer. Detailed Implementation

[0020] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0021] This invention provides a technical solution: a highly elastic waterproof cable based on a blend of water-blocking powder and elastomer, comprising at least the following layered structures from the inside out: Conductor layer: using a highly conductive metal conductor, preferably copper or aluminum core, the conductor diameter can be adjusted according to the cable's current-carrying requirements; Conductor shielding layer: using a semi-conductive elastomer material, preferably semi-conductive ethylene propylene diene monomer (EPDM), to uniformly distribute the surface electric field, avoid electric field distortion caused by uneven conductor surface, and reduce the risk of insulation layer breakdown; Insulation layer: adopting an inner and outer layer gradient structure, combining high elasticity and long-term waterproof function; Insulation shielding layer: using the same material as the conductor shielding layer, used to cooperate with the conductor shielding layer to achieve uniform electric field distribution, while preventing surface discharge of the insulation layer; Sheath layer: using a weather-resistant elastomer material, preferably weather-resistant thermoplastic elastomer (TPE) or EPDM, providing mechanical protection and environmental isolation.

[0022] It should be noted that in the above-mentioned layered structure, the insulation layer is the core of cable performance optimization. Specifically, the insulation layer consists of the following materials by weight: 15-20 parts of modified water-blocking powder, including a water-blocking powder base material and a composite modifier. The water-blocking powder base material is sodium polyacrylate, accounting for 90-95% of the total mass of the modified water-blocking powder, with a water absorption ratio of 300-500 times. The composite modifier is a mixture of silane coupling agent KH-550 and polyether-modified silicone oil, accounting for 5-10% of the total mass of the modified water-blocking powder. The mass ratio of the two is... The ratio is 3:7-6:4, used to improve the compatibility between sodium polyacrylate and the elastomer matrix; 70-80 parts of elastomer matrix, including main elastomer and auxiliary elastomer; wherein the main elastomer is EPDM, accounting for 90-95% of the total mass of the elastomer matrix, with a Mooney viscosity of 45±5; the auxiliary elastomer is ethylene-octene copolymer (POE), accounting for 5-10% of the total mass of the elastomer matrix, with a melt index of 0.5 g / 10 min, used to reduce the modulus of EPDM and improve the flexibility of the insulation layer; 0.5- 1.0 part of a crosslinking regulator, preferably triallyl isocyanurate (TAIC), whose polyallyl groups can react simultaneously with the double bonds of EPDM and a small number of double bonds of POE, reducing the difference in crosslinking density between the two and avoiding stress concentration caused by uneven crosslinking during blending; 1.0-1.5 parts of a dispersing aid, preferably silane coupling agent KH-570 modified nano-silica with a particle size of 50nm, used to prevent the water-blocking powder from agglomerating during blending and improve the dispersion uniformity; 1-2 parts of a softener, preferably... Liquid paraffin was chosen to reduce the melt viscosity of the blend system, improve processing fluidity, and prevent material degradation due to excessive torque during twin-screw extrusion. 1.5-2.0 parts of a crosslinking agent, preferably dicumyl peroxide (DCP), decomposes at high temperatures to generate free radicals, causing the elastomer molecular chains to form a three-dimensional network crosslinked structure. 0.5-1.0 parts of a composite antioxidant, composed of 2,6-di-tert-butyl-p-cresol (BHT) and antioxidant 1010 in a 1:1 mass ratio, were used to improve the material's resistance to heat and oxygen aging. It should be noted that all of the above materials are commercially available.

[0023] It should be further explained that, in order to prevent the nano-silica from agglomerating and forming hard spots due to the large number of hydroxyl groups on the surface of the nano-silica and its poor compatibility with non-polar EPDM during subsequent material mixing, it is necessary to modify the nano-silica first. The specific steps are as follows: Place the nano-silica powder in a high-speed mixer, add 5% of its mass of silane coupling agent KH-570, and stir at 1000 r / min for 1 h at 80℃ to allow the silane coupling agent KH-570 to react with the hydroxyl groups on the surface of the nano-silica to complete the hydrophobic modification. After cooling, pass through a 100-mesh sieve to obtain modified nano-silica. Because sodium polyacrylate (SPA) molecules contain a large number of hydrophilic sodium carboxylate groups (-COONa) and hydroxyl groups (-OH), exhibiting strong hydrophilicity, and the elastomer matrix is ​​a non-polar polymer material with a molecular chain mainly composed of saturated olefin structures, the polarity difference between the two is significant. During mixing, agglomeration easily occurs due to excessive interfacial tension. Therefore, a composite modification with silane coupling agent KH-550 and polyether-modified silicone oil is required. The amino group (-NH2) of silane coupling agent KH-550 can undergo a condensation reaction with the hydroxyl groups of SPA to achieve chemical anchoring, while the flexible non-polar segments of polyether-modified silicone oil can form entanglements with the olefin segments of the elastomer matrix, eliminating the polarity difference and improving the dispersion uniformity and interfacial bonding of SPA in the elastomer matrix. The specific steps are as follows: Place the SPA powder in a vacuum drying oven and dry at 105℃ and -0.09 MPa for 4 hours to remove adsorbed water from the powder surface and prevent subsequent hydrolysis of the modifier; after drying, cool to room temperature and transfer to a sealed container for later use. Weigh KH-550 and polyether-modified silicone oil, dilute with 3 times their weight of anhydrous ethanol, and stir at 500 rpm for 5 minutes to form a homogeneous modifier solution. Add dehydrated sodium polyacrylate powder to a high-speed mixer, and purge with nitrogen at a flow rate of 0.5 L / min for protection; heat to 100°C, adjust the speed to 1200 rpm, and use a peristaltic pump to uniformly spray the modifier solution into the mixer. After spraying, continue stirring for 20 minutes to ensure uniform coating of the modifier on the surface of the sodium polyacrylate; then cool to 80°C and continue stirring at 800 rpm for 15 minutes to allow the modifier to fully react with the hydroxyl groups on the surface of the sodium polyacrylate. Add modified nano-silica to the coated sodium polyacrylate, and stir at 1000 rpm for 15 minutes at 80°C to prevent the sodium polyacrylate particles from agglomerating, utilizing the steric hindrance effect of the modified nano-silica; after stirring, cool to room temperature to obtain the modified water-blocking powder, and store in a sealed container.

[0024] This invention also provides a method for preparing a highly elastic waterproof cable insulation layer based on a blend of water-blocking powder and elastomer. The process steps and parameter settings are described in detail below through specific embodiments.

[0025] Example 1: According to Figure 1As shown, this embodiment provides a method for preparing a highly elastic waterproof cable insulation layer based on a blend of water-blocking powder and elastomer, specifically including the following steps: S1: Start the twin-screw extruder, set the feeding section temperature to 100°C, the melting section temperature to 135°C, and the homogenization section temperature to 110°C, and set the screw speed to 220 r / min; turn on the ultrasonic generator at the end of the homogenization section with a power of 300W, and simultaneously turn on the cooling water jacket to control the temperature of the cooling water jacket below 120°C; preheat for 30 minutes until the temperature of each temperature zone stabilizes at the set value; S2: Add 72.15 parts of EPDM, 4.85 parts of POE, 0.8 parts of TAIC, and 1.5 parts of liquid paraffin to the main feed port of the twin-screw extruder, and start the melting... S3: In the mixing process, mix for 14 minutes until the material is completely plasticized, uniformly translucent, and free of obvious solid particles; S4: Add 18 parts of modified water-blocking powder and 1.2 parts of modified nano-silica through the side feed port of the twin-screw extruder. The modified water-blocking powder consists of 16.2 parts of sodium polyacrylate and 1.8 parts of a composite modifier, with a mass ratio of KH-550 to polyether-modified silicone oil of 1:1 in the composite modifier; continue mixing for 9 minutes, then keep the ultrasonic generator on and disperse for 2.5 minutes, continuously monitoring the material temperature in the homogenization section to ensure it does not exceed 120℃; S5: Extrude the homogenized blend melt through an extrusion die and cut it into 4mm particles using a pelletizer. The chopped granules are transferred to a forced-air drying oven, set to a drying temperature of 80℃, and dried for 2 hours. After drying, the granules are removed, sealed, and stored for later use to obtain blended granules. S5: 75 parts EPDM, 1.8 parts DCP, 0.6 parts composite antioxidant, and 2.5 parts blended granules are added to the main feed port of the twin-screw extruder. The composite antioxidant consists of 0.3 parts BHT and 0.3 parts antioxidant 1010. The melt mixing program is started, and after mixing for 12 minutes, the granules are extruded and granulated with a particle size of 4 mm. After drying at 80℃ for 2 hours, the inner layer pure elastomer granules are obtained. S6: The double-layer co-extrusion die head is started, and the inner core channel and outer channel temperatures are both set to 125℃, the die head pressure is set to 0.9 MPa, and preheating is performed for 2 hours. 0 min: Select a copper core wire with a conductor shielding layer on the surface, heat the surface temperature of the core wire to 80℃, add the inner layer pure elastomer particles to the inner core flow channel hopper, add the blended particles to the outer layer flow channel hopper, start the extrusion program, control the conductor traction speed to 5 m / min, and ensure that there are no bubbles or delamination at the interface between the two layers; S7: Send the extruded insulated core wire into a nitrogen-protected steam crosslinking tube, first enter the preheating section, the preheating section temperature is 120℃, preheat for 5 min; then enter the crosslinking section, the crosslinking section temperature is 170℃, the pressure is 0.8MPa, and the crosslinking treatment is 18 min, during which the volume ratio of nitrogen to steam is controlled at 3:7; S8: Send the crosslinked insulated core wire into the three-stage cooling tank in sequence.First, cool the wire core in an 80℃ hot water bath for 3 minutes, then in a 50℃ warm water bath for 3 minutes, and finally in a 25℃ cold water bath for 2 minutes. After cooling, transfer the insulated wire core into a vacuum drying oven and dry it at 60℃ and -0.08 MPa for 1 hour. After drying, remove the core to complete the preparation of the insulation layer. The core can then proceed directly to conventional processes such as the shielding layer and sheath layer.

[0026] Example 2: Compared with Example 1, the difference in this example is the adjustment of the amount of modified water-blocking powder, as follows: the total amount of modified water-blocking powder added to the side feed port is 15 parts, of which 13.5 parts are sodium polyacrylate and 1.5 parts are composite modifier, and the rest is the same as in Example 1; the purpose is to verify the dispersion uniformity and basic water-blocking ability of the water-blocking powder at low dosage.

[0027] Example 3: Compared with Example 1, the difference in this example is the adjustment of the amount of modified water-blocking powder, as follows: the total amount of modified water-blocking powder added to the side feed port is 20 parts, of which 19 parts are sodium polyacrylate and 1 part is composite modifier, and the rest is the same as in Example 1; the aim is to verify the dispersion stability and enhanced water-blocking ability when the water-blocking powder is used at a high amount.

[0028] Example 4: Compared with Example 1, the difference in this example is the adjustment of the ratio of KH-550 to polyether modified silicone oil in the composite modifier, as follows: the total amount of modified water-blocking powder is still 18 parts, but the mass ratio of KH-550 to polyether modified silicone oil is adjusted to 3:7, and the rest is the same as in Example 1; the aim is to enhance the compatibility of the composite modifier with the non-polar elastomer and verify the interfacial bonding effect when the flexible modifier is dominant.

[0029] Example 5: Compared with Example 1, the difference in this example lies in the ratio of KH-550 to polyether-modified silicone oil in the composite modifier, as follows: the total amount of modified water-blocking powder remains unchanged at 18 parts, the mass ratio of silane coupling agent KH-550 to polyether-modified silicone oil is adjusted to 6:4, and the rest remains the same as in Example 1; the aim is to strengthen the chemical anchoring of the composite modifier and polar sodium polyacrylate, and to verify the interfacial bonding effect when the polar modifier is dominant.

[0030] Example 6: Compared with Example 1, the difference in this example is the amount of modified nano silica used, as follows: 1.0 part of modified nano silica is added to the side feed port, and the rest is the same as in Example 1; the purpose is to verify whether the minimum amount of dispersant is sufficient to inhibit the agglomeration of water-blocking powder, and to avoid the increase in cost and potential impact on the mechanical properties of elastomer caused by excessive additives.

[0031] Example 7: Compared with Example 1, the difference in this example is the amount of modified nano silica used, as follows: 1.5 parts of modified nano silica are added to the side feed port, and the rest is the same as in Example 1; the purpose is to verify the dispersion effect of water-blocking powder under the dosage of high dispersing agent, and at the same time to investigate whether nano silica, as a rigid particle, will have a negative impact on the elasticity of the insulation layer.

[0032] Comparative Example 1: Compared with Example 1, the difference in this comparative example is that the modified water-blocking powder did not contain a composite modifier, specifically as follows: the modified water-blocking powder contained only 16.2 parts of unmodified sodium polyacrylate, without silane coupling agent KH-550 and polyether modified silicone oil, and 16.2 parts of unmodified sodium polyacrylate and 1.2 parts of modified nano silica were directly added at the side feed port, with the rest remaining the same as in Example 1; the aim was to verify the effect of the composite modifier on improving the compatibility between sodium polyacrylate and the elastomer matrix.

[0033] Comparative Example 2: Compared with Example 1, the difference in this comparative example is that no modified nano-silica was added. Specifically, only 18 parts of modified water-blocking powder were added to the side feed port, including 16.2 parts of sodium polyacrylate and 1.8 parts of composite modifier. The mass ratio of silane coupling agent KH-550 to polyether modified silicone oil in the composite modifier was 1:1. No modified nano-silica was added, and the rest was the same as in Example 1. The aim was to verify the anti-agglomeration effect of modified nano-silica.

[0034] Comparative Example 3: Compared with Example 1, the difference in this comparative example is that the ultrasonic dispersion step of the homogenization stage is omitted. Specifically, in the S3 blending and dispersion stage, only 9 minutes of mixing is performed, the ultrasonic generator is not turned on, and the rest is the same as in Example 1; the aim is to verify the enhancing effect of ultrasonic dispersion on the dispersion effect of water-blocking powder.

[0035] Comparative Example 4: Compared with Example 1, the difference in this comparative example is that the insulating layer is a single-layer structure without an inner transition elastomer. Specifically, the preparation of the pure elastomer particles in the inner layer of S5 is not carried out. In the S6 double-layer co-extrusion stage, only the blended particles are added through the outer layer flow channel to extrude a single-layer blended water-blocking layer. The rest is consistent with Example 1. The aim is to verify the effect of the gradient structure on the interfacial bonding force.

[0036] Comparative Example 5: This comparative example refers to the preparation method mentioned in the pressure-resistant water-blocking layer and the insulated cable with the layer in the announcement number CN120221179A, and prepares a layered waterproof structure, wherein the insulation layer is made of pure EPDM with a thickness of 0.6mm, and the outer layer is formed by wrapping a water-blocking cloth with 20% acrylate water-blocking powder to form a 0.2mm thick waterproof layer; the purpose is to compare the performance differences between the present invention and the existing layered structure.

[0037] Preparation Example 1: According to Figures 2-3As shown, this invention also proposes a highly elastic waterproof cable based on a blend of water-blocking powder and elastomer, comprising a single-core stranded conductor layer 1, and a conductor shielding layer 2, an insulation layer 3, an insulation shielding layer 4, and a sheath layer 5, which are sequentially wrapped around the conductor layer 1 from the inside out. Each structural layer is tightly fitted and coaxially arranged to form a complete electrical isolation and mechanical protection system. Specific structural information and functions are as follows: The conductor layer 1 is the core of the cable's current transmission, with an overall diameter of 4.0 mm, a surface roundness error ≤0.1 mm, and no burrs or oxide layer defects; the conductor shielding layer 2 tightly wraps around the outer periphery of the conductor layer 1, with a fixed thickness of 0.5 mm and a volume resistivity ≤1×10⁻⁶. 3 The surface roughness is ≤0.05mm, and the adhesion to conductor layer 1 is ≥95%. This eliminates electric field distortion on the surface of conductor layer 1, achieving a uniform electric field transition between conductor layer 1 and insulation layer 3, and avoiding insulation failure caused by local electric field concentration. Insulation layer 3 is the core insulation and waterproof functional layer of the cable, tightly covering the outer periphery of conductor shielding layer 2, with a total thickness of 1.5mm. It adopts a gradient composite structure design, including an inner insulation layer 6 and an outer insulation layer 7, with a thickness ratio of 3:2. The inner insulation layer 6 is a pure elastomer transition layer, which can alleviate the performance abrupt change between conductor shielding layer 2 and outer insulation layer 7 and reduce interface stress concentration. The outer insulation layer 7 tightly covers the outer periphery of the inner insulation layer 6, which can ensure insulation performance while achieving self-sealing of gaps after water contact. Insulation shielding layer 4 tightly covers the outer periphery of insulation layer 3, with a thickness of 0.5mm, and is a semi-conductive elastomer layer with a volume resistivity ≤1×10⁻⁶. 3 The insulation shielding layer 4 has a thickness of 1.0 mm and a fit of ≥95% with the insulation layer 3. It can shield stray electric fields outside the insulation layer 3 to avoid external interference affecting the electrical performance of the cable, and at the same time provide a flat bonding interface for the sheath layer 5. The sheath layer 5 is the outermost mechanical protection and environmental adaptation layer of the cable. It tightly covers the outer periphery of the insulation shielding layer 4, resists external mechanical wear, compression and erosion in humid environments, protects the structural integrity of the internal functional layers, and extends the service life of the cable.

[0038] Preparation Example 2: According to Figures 4-5As shown, this invention also proposes a highly elastic waterproof cable based on a blend of water-blocking powder and elastomer, comprising a multi-core stranded conductor layer 1. The difference from Preparation Example 1 is that the conductor layer 1 is a cable core formed by stranding three independent single-core conductors, each with a diameter of 2.0 mm, resulting in an overall cable core diameter of approximately 4.5 mm. The surface roundness error of the cable core is ≤0.2 mm, with no obvious protrusions or depressions. The stranding gap ratio is controlled at 12%-15%, reserving space for subsequent filling layers. In this preparation example, the material selection and thickness ratio of the conductor shielding layer 2, insulation layer 3, and insulation shielding layer 4 covering the outside of each single-core conductor are consistent with those of Preparation Example 1, ensuring that the electric field uniformity, high elastic recovery capability, and long-term waterproof performance of each single core are equivalent to the single-core cable of Preparation Example 1. To prevent the core function from being weakened due to the multi-core structure, a filling layer 8 and a wrapping layer 9 are added between the insulation shielding layer 4 and the sheath layer 5. The filling layer 8 tightly fills the triangular gap formed by the three single cores twisted together, eliminating the gaps in the multi-core twisting and preventing local stress concentration caused by the irregularity of the cable core in the subsequent wrapping layer 9 and sheath layer 5. At the same time, it prevents the insulation layer from being worn due to the displacement of the single core when the cable is bent, ensuring the stability of the multi-core structure. The wrapping layer 9 tightly covers the outer periphery of the filled overall cable core. It is a polyester non-woven fabric wrapping layer with a fixed thickness of 0.4mm. It forms a transition interface between the filling layer 8 and the subsequent sheath layer 5, preventing air bubbles from being generated due to the uneven surface of the filling layer 8 when the sheath layer 5 is extruded. It can also buffer the deformation stress between the sheath layer 5 and the internal single core, reducing interface wear during long-term dynamic service.

[0039] Performance testing: To verify the core performance of the high-elasticity waterproof cable insulation layer based on the blending of water-blocking powder and elastomer of the present invention, the complete insulated wire cores prepared in Examples 1-7 and Comparative Examples 1-4 were used as test objects. Systematic tests were carried out on interface bonding force, elastic performance, waterproof performance and insulation performance. The specific test plan is as follows.

[0040] Test Example 1: This test example focuses on the interfacial bonding reliability between the insulation layer and the conductor shielding layer. Static strength and dynamic stability tests are used to evaluate the interlayer delamination resistance. Specific test items and procedures are as follows: According to GB / T2951.31-2008 "General Test Methods for Insulation and Sheathing Materials of Cables and Optical Fibers - Part 31: Environmental Stress Cracking Resistance Test, Melt Flow Rate Determination Test and Peel Strength Test of Polyolefin Insulation and Sheathing Materials", 100mm long insulated core samples are cut from each sample. The insulation layer and conductor shielding layer are carefully peeled off at one end using a cutting tool. The conductor shielding layer is then fixed in the lower clamp of the universal tensile testing machine, and the insulation layer is fixed in the upper clamp. The tensile speed is set to 50mm / min, and the tensile testing machine is started for the peel test. The tensile force changes are recorded in real time during the test, and the average value during the stable phase is taken. Peel strength was calculated based on the sample width. The insulated wire core was machined into a cylindrical sample with a diameter of 10 mm and a height of 8 mm, ensuring the interface between the conductor shield and the insulation layer was fully exposed and perpendicular to the sample axis. A special shearing fixture was used to fix the sample, ensuring the shearing force direction was parallel to the interface. The shearing speed of the tensile testing machine was set to 10 mm / min, and shearing force was applied until the interface failed. The maximum shearing force at failure was recorded, and the shear strength was calculated based on the shear surface area. A 500 mm long insulated wire core sample was cut and placed on a dynamic bending testing machine. The bending radius was set to 20 mm, the bending angle to ±90°, and the cycle frequency to 1 cycle / s, completing 1000 dynamic bending cycles. After the cycles, the peel strength was measured, and the peel strength retention rate was calculated based on the peel strength, reflecting the degree of attenuation of the interface bonding force after service.

[0041] The specific test results are shown in Table 1:

[0042] As shown in Table 1, the interfacial bonding performance between the insulating layer and the conductor shielding layer in Examples 1-7 of this invention is significantly better than that in Comparative Examples 1-5. Specifically, the peel strength of Examples 1-7 is 1.5-2.0 N / mm, the shear strength is 2.8-3.5 MPa, and the peel strength retention rate after 1000 dynamic bending cycles reaches 79-88%; while the peel strength of Comparative Examples 1-5 is only 0.7-1.2 N / mm, the shear strength is only 1.4-1.9 MPa, and the retention rate after dynamic cycling is only 48-60%, showing a significant performance difference; Comparative Example 1, due to the lack of a composite modifier, cannot eliminate the polarity difference between sodium polyacrylate and the elastomer matrix, and its peel strength is only... The shear strength of Comparative Example 4 was 44% of that of Example 1, demonstrating that the composite modifier can effectively improve the interfacial bonding state between the water-blocking powder and the elastomer through the condensation of amino and hydroxyl groups and the entanglement of non-polar segments. Comparative Example 4 did not have an inner transition elastomer, and there was no performance buffer interface between the insulation layer and the conductor shielding layer. Its shear strength decreased by 50% compared to Example 1, demonstrating the effect of the gradient structure on alleviating interfacial stress and avoiding the attenuation of interlayer bonding force due to sudden performance changes. Comparative Example 5 adopted the existing layered structure, and its peel strength retention rate after dynamic cycling was only 48%, far lower than the 85% of Example 1, confirming that the water-blocking powder and elastomer blending design of the present invention can effectively solve the interlayer separation problem of the layered structure in dynamic service.

[0043] Test Example 2: This test example focuses on the deformation recovery and mechanical load-bearing capacity of the insulation layer. Tensile tests are used to evaluate the synergy between its elasticity and strength. The specific test items and procedures are as follows: The test is conducted according to GB / T528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". The core evaluation is the deformation capacity of the insulation layer. The insulation layer is peeled from the wire core and processed into dumbbell-shaped specimens. The specimen thickness is consistent with the actual insulation layer thickness, uniformly 0.6 mm. The gauge length is 25 mm long and 4 mm wide. The specimen is installed in the upper and lower clamps of a universal tensile testing machine, ensuring that the specimen axis is aligned with the direction of tensile force. The tensile speed is set to 200 mm / min. After starting the test, the gauge length is recorded in real time. The elongation was measured until the specimen broke, and the elongation at break was calculated based on the gauge length elongation at break. A dumbbell-shaped specimen of the same specifications as the one used for the elongation at break test was used. The specimen was stretched to 100% constant elongation, i.e., the gauge length was stretched from 25 mm to 50 mm, and held at this deformation state for 10 minutes to simulate a long-term stress scenario. The tension was then released, and the specimen was allowed to recover naturally at room temperature for 10 minutes. The length of the gauge length after recovery was measured, and the elastic recovery rate was calculated based on the permanent deformation. Using the same dumbbell-shaped specimen, it was mounted on a universal tensile testing machine, and a tensile force was applied at a tensile speed of 200 mm / min until the specimen broke. The maximum tensile force at break was recorded, and the tensile strength was calculated based on the effective cross-sectional area of ​​the specimen.

[0044] The specific test results are shown in Table 2:

[0045] As can be seen from the data in Table 2, the elastic properties of Examples 1-7 generally meet the high elasticity design target and are superior to those of the comparative examples: the elongation at break of Examples 1-7 is 345-380%, the elastic recovery rate at 100% constant elongation is 89-93%, and the tensile strength is 8.6-9.5 MPa; the elongation at break of Comparative Examples 1-5 is only 270-310%, the elastic recovery rate is only 72-82%, and the tensile strength is only 6.2-7.2 MPa; because Comparative Example 1 uses unmodified sodium polyacrylate, the particle agglomeration destroys the continuous phase structure of the elastomer matrix, and its elongation at break is 23% lower than that of Example 1, and its tensile strength is only 71% of that of Example 1.

[0046] Test Example 3: This test example comprehensively evaluates the waterproof reliability of the insulation layer from three dimensions: short-term water resistance, long-term weather resistance, and longitudinal water penetration resistance. The specific test items and procedures are as follows: A 500mm long insulated wire core sample is cut, and both ends of the sample are sealed. The sealed sample is then immersed in deionized water at 25℃, ensuring an immersion depth of 100mm. Simultaneously, a hydrostatic pressure of 0.2MPa is applied to the water using a water pressure device to simulate a water pressure scenario in a humid environment. The insulation resistance of the sample is measured using a high-resistance meter before immersion and after 24 hours of immersion. The insulation resistance reduction rate is calculated based on the two resistance values. The lower the reduction rate, the better the short-term water resistance performance. The same specifications as those used in the short-term water resistance test are employed. Insulated wire core samples were subjected to 50 cycles of wet and dry treatment. After soaking in deionized water at 25°C for 8 hours, they were dried in a forced-air dry environment at 60°C for 16 hours to simulate the alternating wet and dry environment in actual service. After the cycle, the insulation resistance was measured using the same method as the short-term water resistance test, and the water resistance retention rate was calculated to reflect the degree of degradation of waterproof performance under long-term environmental conditions. Insulated wire core samples with a length of 1000 mm were cut, one end of the sample was sealed with epoxy resin, and the other end was connected to a water pressure supply device through a sealing joint. A water pressure of 0.3 MPa was applied to the inside of the sample, and it was observed whether water seeped out from the sealed end of the sample. The time it took for water to seep from the water inlet end of the sample to the sealed end was recorded, and the longitudinal water permeability was calculated based on the water permeation time.

[0047] The specific test results are shown in Table 3:

[0048] According to the data in Table 3, the waterproof performance of Examples 1-7 is significantly better than that of the comparative examples, specifically: the short-term water-blocking insulation resistance reduction rate of Examples 1-7 is 6.2-13.5%, the water-blocking retention rate after long-term wet and dry cycles is 80-91%, and the longitudinal water permeability is ≤0.0521 / h; the short-term resistance reduction rate of Comparative Examples 1-5 is 18.7-30.8%, the long-term retention rate is 55-70%, and the longitudinal water permeability is 0.128-0.2171 / h; the short-term resistance reduction rate of Comparative Example 3 is 18.7-30.8%, the long-term retention rate is 55-70%, and the longitudinal water permeability is 0.128-0.2171 / h; the short-term resistance reduction rate of Comparative Example 3 is 18.7-30.8%, the long-term water-blocking retention rate is 55-70%, and the longitudinal water permeability is 0.128-0.2171 / h; the short-term water-blocking insulation resistance reduction rate of Comparative Example 3 is 18.7-30.8%, the long-term water-blocking insulation resistance reduction rate ... The water-blocking insulation resistance reduction rate was 120% higher than that of Example 1, proving that ultrasonic dispersion can enhance the dispersion uniformity of water-blocking powder in the elastomer, forming a continuous water-blocking barrier and avoiding local water-permeable channels caused by uneven dispersion. Example 3 had the lowest short-term resistance reduction rate and the highest long-term water-blocking retention rate, demonstrating the enhancing effect of high water-blocking powder dosage on waterproofing ability. The longitudinal water permeability of Comparative Example 5 was 0.2171 / h, which is 5.2 times that of Example 1, confirming that the blended structure of the present invention can avoid the longitudinal water-permeable channels formed by interlayer separation in the layered structure and improve the long-term waterproofing effect.

[0049] Test Example 4: This test example focuses on the core electrical isolation function of the insulation layer. Through resistivity, breakdown strength, and energy loss tests, it ensures that the insulation meets the requirements for safe cable operation. The specific test items and procedures are as follows: According to GB / T1410-2006 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", the insulation layer is peeled from the core and processed into circular samples. The sample surface is ensured to be flat, free of bubbles and impurities. A three-electrode system is used to fix the sample, and the sample and electrode system are placed in a constant temperature environment of 23℃. After applying voltage, the sample is allowed to stand for 10 minutes. Subsequently, the volume resistivity is measured using a high-resistivity meter. The volume resistivity is calculated based on the sample size. The higher the volume resistivity, the stronger the charge barrier capability of the insulation layer. A circular sample of the same specifications as the one used for the volume resistivity test is placed... Between the two parallel electrodes of the oil-immersion breakdown tester, insulating oil is used as the medium to avoid interference from air breakdown. The voltage rise rate of the tester is set to 2kV / s, and the voltage between the electrodes is gradually increased until the sample breaks down. The voltage value at the time of breakdown is recorded, and the breakdown field strength is calculated in combination with the sample thickness. The higher the breakdown field strength, the stronger the insulation layer's resistance to electrical breakdown. Using the above-mentioned circular sample, a precision dielectric loss meter is used for testing. The power frequency is 50Hz, the test voltage is 1kV, and the ambient temperature is 23℃. The sample is installed on the test fixture of the dielectric loss meter, and after the voltage is applied, it is stabilized for 3 minutes. Then the dielectric loss tangent (tanδ) is recorded. This value reflects the energy loss of the insulating material in the electric field due to polarization hysteresis, etc. The smaller the tanδ, the more stable the electrical performance of the insulation layer and the lower the energy loss during operation.

[0050] The specific test results are shown in Table 4:

[0051] Table 4 shows that the insulation performance of Examples 1-7 meets the requirements for safe operation of low-voltage cables and is superior to that of the comparative example: the volume resistivity of Examples 1-7 is 1.5 × 10⁻⁶. 15 -3.1×10 15 The dielectric constant is Ω·cm, the breakdown field strength is 20.2-22.1 kV / mm, and the dielectric loss tangent is 0.0038-0.0048; the volume resistivity of Comparative Examples 1-5 is only 5.6 × 10⁻⁶. 13 -1.5×10 14 The volume resistivity of Example 1 was only 3.3% of that of Example 1 due to the unmodified sodium polyacrylate, and the breakdown field strength was only 14.9-17.8 kV / mm, and the dielectric loss tangent was only 0.0076-0.0103. This shows that the composite modification can eliminate the polarity defects of the water-blocking powder and avoid the deterioration of insulation performance. The insulation performance of Examples 6 and 7 was not significantly different from that of Example 1, indicating that within the dosage range of 1-1.5 parts, the modified nano silica can ensure the dispersion effect without affecting the electrical performance of the insulation layer.

[0052] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer, characterized in that, From the inside out, it includes a conductor layer, a conductor shielding layer, an insulation layer, an insulation shielding layer, and a sheath layer. The insulation layer is a composite structure of inner and outer layers. The insulation layer includes an inner insulation layer and an outer insulation layer distributed radially along the cable. The inner insulation layer is a pure elastomer transition layer, and the outer insulation layer is a blend layer of modified water-blocking powder and elastomer matrix.

2. The highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 1, characterized in that: The insulating outer layer comprises, by weight, 15-20 parts modified water-blocking powder, 70-80 parts elastomer matrix, 0.5-1.0 parts crosslinking regulator, 1.0-1.5 parts dispersant, 1-2 parts softener, 1.5-2.0 parts crosslinking agent, and 0.5-1.0 parts composite antioxidant. The crosslinking regulator is triallyl isocyanurate, the softener is liquid paraffin, and the crosslinking agent is dicumyl peroxide.

3. The highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 2, characterized in that: The modified water-blocking powder comprises a water-blocking powder substrate and a composite modifier. The water-blocking powder substrate is sodium polyacrylate, which accounts for 90-95% of the total mass of the modified water-blocking powder. The composite modifier accounts for 5-10% of the total mass of the modified water-blocking powder and is used to improve the compatibility between sodium polyacrylate and the elastomer matrix.

4. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 3, characterized in that: The composite modifier is a mixture of silane coupling agent KH-550 and polyether modified silicone oil, with a mass ratio of silane coupling agent KH-550 to polyether modified silicone oil of 3:7-6:

4. The silane coupling agent KH-550 is used to achieve chemical anchoring by undergoing a condensation reaction with the hydroxyl groups of sodium polyacrylate, and the polyether modified silicone oil is used to improve the entanglement compatibility with the elastomer matrix.

5. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 1, characterized in that: The elastomer matrix includes a main elastomer and an auxiliary elastomer. The main elastomer is ethylene propylene diene monomer (EPDM) rubber, accounting for 90-95% of the total mass of the elastomer matrix, and the auxiliary elastomer is ethylene-octene copolymer, accounting for 5-10% of the total mass of the elastomer matrix.

6. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 2, characterized in that: The dispersing agent is nano-silica modified with silane coupling agent KH-570, and the amount of silane coupling agent KH-570 is 5% of the mass of nano-silica.

7. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 2, characterized in that: The composite antioxidant is composed of 2,6-di-tert-butyl-p-cresol and antioxidant 1010 in a mass ratio of 1:

1.

8. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 1, characterized in that: The insulating inner layer comprises, by weight, 75 parts EPDM rubber, 1.8 parts dicumyl peroxide, 0.6 parts composite antioxidant, and 2.5 parts blended particles. The blended particles are a blend of elastomer and modified water-blocking powder. The raw materials for its preparation include an elastomer matrix, modified water-blocking powder, dispersant, and crosslinking regulator, which are used to improve the interfacial compatibility between the insulating inner layer and the insulating outer layer.

9. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 1, characterized in that: When the cable core is formed by stranding multiple conductors, a filler layer and a wrapping layer are also included between the insulation shield layer and the sheath layer.

10. A highly elastic waterproof cable based on a blend of water-blocking powder and elastomer according to claim 1, characterized in that: The preparation steps of the insulating layer include: S1: Drying sodium polyacrylate at 105℃ and -0.09MPa for 4 hours, cooling it, and mixing it with a composite modifier diluted with 3 times anhydrous ethanol under nitrogen protection and at 100℃, then adding modified nano-silica and stirring evenly, and cooling to obtain modified water-blocking powder; S2: Starting a twin-screw extruder, controlling the homogenization section temperature at 110℃, first adding EPDM rubber, ethylene-octene copolymer, triallyl isocyanurate and liquid paraffin for melt mixing, then adding modified water-blocking powder, mixing and then starting ultrasonic dispersion, extruding and pelletizing, and drying at 80℃ for 2 hours to obtain blended granules. S3: Add EPDM rubber, dicumyl peroxide, composite antioxidant and blended granules to the twin-screw extruder, melt and mix, then extrude and granulate to form the inner insulating layer material; S4: Start the double-layer co-extrusion die head, feed the inner insulating layer material and the outer insulating layer blended granules into the inner and outer layer channels respectively, and extrude simultaneously to coat the conductor shielding layer; S5: Send the extruded core into the nitrogen-protected steam crosslinking tube, at 170℃ and 0.8MPa, control the nitrogen to steam volume ratio of 3:7, crosslink for 18min, then cool with gradient water temperature, and finally place it under vacuum drying at 60℃ and -0.08MPa for 1h to form the insulating layer.

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