A high elasticity waterproof cable based on water-blocking powder and elastomer blend

Abstract

The application relates to the technical field of electric wires and cables, and discloses a high-elasticity waterproof cable based on water-blocking powder and elastomer blending, which aims to solve the problem that, in the prior art, interlayer separation is easily caused by interface stress superposition during long-term dynamic service, leading to elastic attenuation and damage of a waterproof barrier; the sodium polyacrylate water-blocking powder is modified by compounding, is blended with an elastomer matrix, is matched with modified nano-silica dispersion, a gradient insulation structure of inner and outer layers is designed, and processes such as ultrasonic dispersion, nitrogen protection steam crosslinking, etc. are combined; the cable is sequentially provided with a conductor layer, a conductor shielding layer, a gradient insulation layer, an insulation shielding layer and a sheath layer from inside to outside, interface stress concentration is reduced, interlayer combination stability is enhanced, the cable can still maintain 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] Technical effects and advantages of the present application: in the present application, through the synergistic cooperation of the blending of modified water-blocking powder and elastomer matrix, high elasticity and long-acting waterproof are realized simultaneously, the modified water-blocking powder first undergoes condensation reaction between the amino group of silane coupling agent KH-550 and the hydroxyl group of sodium polyacrylate, and then forms entanglement with the nonpolar chain segment of polyether modified silicone oil and the molecular chain of elastomer, eliminating the polarity difference between the two; meanwhile, the steric hindrance effect of modified nano-silicon dioxide is used to prevent the agglomeration of sodium polyacrylate particles; the elastomer matrix mainly uses EPDM as the main body and POE as the auxiliary, and the rigidity and flexibility of the material are balanced through the optimization of the ratio of the two, forming a complete and continuous elastic phase, solving the problem of interlayer separation that easily occurs in the long-term dynamic service of the existing layered structure, reducing the interface stress concentration, enhancing the interlayer bonding stability, so that the cable can still maintain excellent elastic recovery ability and waterproof barrier integrity under high-frequency torsion and repeated wet-dry cycles. In the present application, the gradient insulation layer and the ultrasonic dispersion process are used in cooperation, taking into account the structural stability and insulation reliability, the gradient insulation layer uses the inner layer transition elastomer to realize the smooth connection of the performance of the conductor shielding layer and the outer layer blending water-blocking layer, and weakens the interface shear stress caused by the performance mutation; the outer layer blending water-blocking layer is prepared by using the ultrasonic dispersion process, so that the modified water-blocking powder is uniformly distributed in the elastomer matrix, forming a continuous and uninterrupted water-blocking barrier, avoiding the generation of local water permeation channels, and without the need for additional independent water-blocking layer, which not only ensures that the key insulation performance such as volume resistivity and breakdown field strength meets the safety requirements of low-voltage cables, but also improves the overall mechanical property consistency of the insulation layer, reduces the accumulation of residual stress in static standing and dynamic deformation cycles, and reduces the risk of insulation failure. BRIEF DESCRIPTION OF DRAWINGS

[0017] The disclosure of the present application will be described 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 the present application. In the drawings, the same reference numerals are used to refer to the same parts:

[0018] Figure 1 Preparation flowchart of the high-elasticity waterproof cable insulation layer of the present application; Figure 2 Stereoscopic structure schematic diagram of the high-elasticity waterproof cable provided by Preparation Example 1 of the present application; Figure 3 Stereoscopic structure schematic diagram of the cable from another angle provided by Preparation Example 1 of the present application; Figure 4 Stereoscopic structure schematic diagram of the high-elasticity waterproof cable provided by Preparation Example 2 of the present application; Figure 5 Stereoscopic structure schematic diagram of the cable from another angle provided by Preparation Example 2 of the present application.

[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, filling layer; 9, wrapping layer. DETAILED DESCRIPTION

[0020] It is easy to understand that according to the technical solution of the present application, those skilled in the art can propose various structural modes and implementation modes which can be replaced with each other without changing the essential spirit of the present application. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present application, and should not be regarded as the whole or regarded as the limitation or restriction of the technical solution of the present application.

[0021] The present application provides a technical solution: a high-elasticity waterproof cable based on water-blocking powder and elastomer blending, which comprises at least the following ring layer structures from inside to outside: a conductor layer: a high-conductivity metal conductor is adopted, preferably a copper core or an aluminum core, and the conductor diameter can be adjusted according to the current-carrying requirement of the cable; a conductor shielding layer: a semi-conductive elastomer material is adopted, preferably semi-conductive ethylene-propylene-diene rubber (EPDM), which is used for uniform surface electric field, avoiding electric field distortion caused by uneven conductor surface, and reducing the risk of insulation layer breakdown; an insulation layer: a gradient structure of inner and outer layers is adopted, which has high elasticity and long-acting waterproof function; an insulation shielding layer: the material is consistent with that of the conductor shielding layer, which is used to cooperate with the conductor shielding layer to realize uniform distribution of electric field and prevent surface discharge of the insulation layer; a sheath layer: a weather-resistant elastomer material is adopted, preferably weather-resistant thermoplastic elastomer (TPE) or EPDM, which plays a mechanical protection and environmental isolation role.

[0022] It needs to be particularly pointed out that in the above-mentioned ring layer structure, the insulating layer is the core of cable performance optimization. Specifically, the insulating layer is composed of the following materials by weight: 15-20 parts of modified water-blocking powder, including water-blocking powder base material and composite modifier, wherein the water-blocking powder base material is sodium polyacrylate, accounting for 90-95% of the total mass of the modified water-blocking powder, and the water absorption ratio is 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, and the mass ratio of the two is 3:7-6:4, which is used to improve the compatibility of sodium polyacrylate and 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, and the Mooney viscosity is 45±5; the auxiliary elastomer is ethylene-octene copolymer (POE), accounting for 5-10% of the total mass of the elastomer matrix, and the melt index is 0.5 g / 10 min, which is used to reduce the modulus of EPDM and improve the flexibility of the insulating layer; 0.5-1.0 parts of crosslinking regulator, preferably triallyl isocyanurate (TAIC), the multiple allyl groups in its molecule can react with the double bonds of EPDM and a small amount of double bonds of POE, reducing the difference in crosslinking density of the two, and avoiding stress concentration during blending due to uneven crosslinking; 1.0-1.5 parts of dispersing aid, preferably silane coupling agent KH-570 modified nano silicon dioxide with a particle size of 50 nm, which is used to prevent the agglomeration of water-blocking powder during blending and improve the uniformity of dispersion; 1-2 parts of softening agent, preferably liquid paraffin, which is used to reduce the melt viscosity of the blending system, improve the processing fluidity, and avoid material degradation due to excessive torque during double screw extrusion; 1.5-2.0 parts of crosslinking agent, preferably dicumyl peroxide (DCP), which decomposes to produce free radicals at high temperature, making the elastomer molecular chain form a three-dimensional network crosslinking structure; 0.5-1.0 parts of composite antioxidant, composed of 2,6-di-tert-butyl-p-cresol (BHT) and antioxidant 1010 in a mass ratio of 1:1, which is used to improve the heat-oxidative aging resistance of the material. It needs to be pointed out that the above-mentioned materials are commercially available.

[0023] It needs to be further explained that, in order to prevent the mixing of subsequent materials, due to the large amount of hydroxyl groups on the surface of nano-silicon dioxide, the compatibility with non-polar EPDM is poor, and it is easy to form hard points by agglomeration, so it is necessary to modify the nano-silicon dioxide first, the specific steps are as follows: the nano-silicon dioxide powder is placed in a high-speed mixer, 5% of the mass of silane coupling agent KH-570 is added, and it is stirred at 80℃ for 1h at 1000r / min, so that the silane coupling agent KH-570 reacts with the hydroxyl groups on the surface of the nano-silicon dioxide, and the hydrophobic modification is completed, and after cooling, the modified nano-silicon dioxide is obtained by passing through a 100 mesh screen. Due to the fact that the polyacrylic acid sodium molecular chain contains a large number of hydrophilic carboxyl sodium groups (-COONa) and hydroxyl groups (-OH), it shows strong hydrophilicity, the elastomer matrix is a non-polar polymer material, and the molecular chain is mainly composed of saturated olefin structure, so the polarity difference between the two is significant, and when mixed, agglomeration may occur due to excessive interfacial tension, so it is necessary to composite modify the polyacrylic acid sodium with silane coupling agent KH-550 and polyether modified silicone oil; the amino group (-NH2) of the silane coupling agent KH-550 can be condensed with the hydroxyl group of the polyacrylic acid sodium to realize chemical anchoring, and the flexible non-polar segment of the polyether modified silicone oil can be entangled with the olefin segment of the elastomer matrix to eliminate the polarity difference and improve the dispersion uniformity and interfacial bonding force of the polyacrylic acid sodium in the elastomer matrix. The specific steps are as follows: the polyacrylic acid sodium powder is placed in a vacuum drying oven, dried at 105℃ and -0.09Mpa for 4h, and the adsorbed water on the surface of the powder is removed to avoid hydrolysis of the subsequent modifier; after drying, it is cooled to room temperature, and then transferred into a sealed container for standby. KH-550 and polyether modified silicone oil are weighed, 3 times the mass of anhydrous ethanol is added for dilution, stirring is carried out at a speed of 500r / min for 5min, and a uniform modifier solution is formed. The dehydrated polyacrylic acid sodium powder is added to the high-speed mixer, and nitrogen gas is introduced at a flow rate of 0.5L / min for protection; the temperature is raised to 100℃, the rotating speed is adjusted to 1200r / min, the modifier solution is sprayed into the mixer at a constant speed by using a peristaltic pump, and after the spraying is completed, the stirring is continued for 20min to ensure that the surface of the polyacrylic acid sodium is uniformly coated with the modifier; then the temperature is lowered to 80℃, and the stirring is continued at a speed of 800r / min for 15min to make the modifier react with the hydroxyl groups on the surface of the polyacrylic acid sodium. The modified nano-silicon dioxide is added to the coated polyacrylic acid sodium, and stirred at 1000r / min for 15min at 80℃ to prevent the agglomeration of the polyacrylic acid sodium particles by using the steric hindrance effect of the modified nano-silicon dioxide; after the stirring is completed, it is cooled to room temperature to obtain the modified water-blocking powder, which is sealed and stored.

[0024] The application also provides a preparation method of a high-elasticity waterproof cable insulation layer based on the blending of water-blocking powder and elastomer.

[0025] Example 1: according to Figure 1As shown, the embodiment provides a preparation method of high-elasticity waterproof cable insulation layer based on water-blocking powder and elastomer blending, which specifically comprises the following steps: S1: start the double screw extruder, set the feeding section to 100 DEG C, the melting section to 135 DEG C, and the homogenizing section to 110 DEG C, set the screw rotation speed to 220 r / min, turn on the ultrasonic generator at the end of the homogenizing section with a power of 300 W, and simultaneously turn on the cooling water jacket to control the temperature of the cooling water jacket below 120 DEG C, preheat for 30 min until the temperature of each temperature zone is stable 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 feeding port of the double screw extruder, start the melting and mixing program, mix for 14 min until the material is completely plasticized, the material is uniform and translucent, and there are no obvious solid particles; S3: add 18 parts of modified water-blocking powder and 1.2 parts of modified nano silicon dioxide through the side feeding port of the double screw extruder, wherein the modified water-blocking powder is 16.2 parts of sodium polyacrylate and 1.8 parts of a composite modifier, and the mass ratio of KH-550 to polyether modified silicone oil in the composite modifier is 1:1; continue mixing for 9 min, keep the ultrasonic generator on, and disperse for 2.5 min, and continuously monitor the material temperature of the homogenizing section during the period to ensure that the temperature does not exceed 120 DEG C; S4: extrude the blended melt after homogenization through the extrusion die, cut it into particles with a particle size of 4 mm through the granulator, transfer the cut particles into the air drying oven, set the drying temperature to 80 DEG C, dry for 2 h, take out the particles after drying is completed, seal them for later use, and obtain blended particles; S5: add 75 parts of EPDM, 1.8 parts of DCP, 0.6 parts of a composite antioxidant, and 2.5 parts of blended particles to the main feeding port of the double screw extruder, wherein the composite antioxidant is composed of 0.3 parts of BHT and 0.3 parts of antioxidant 1010, start the melting and mixing program, extrude and granulate after mixing for 12 min, the particle size of the particles is 4 mm, and the particles are dried at 80 DEG C for 2 h to obtain inner layer pure elastomer particles; S6: start the double-layer co-extruder head, set the temperature of the inner core flow channel and the outer layer flow channel to 125 DEG C, the head pressure to 0.9 MPa, preheat for 20 min, select a copper core wire core with a surface coated with a conductor shielding layer, heat the surface temperature of the wire core to 80 DEG C, 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 be 5 m / min, and there are no bubbles and no stratification at the interface of the two layers; S7: send the extruded insulation wire core into the nitrogen protection steam crosslinking pipe, first enter the preheating section with a temperature of 120 DEG C and preheat for 5 min; then enter the crosslinking section with a temperature of 170 DEG C and a pressure of 0.8 MPa, and crosslink for 18 min, during which the volume ratio of nitrogen to steam is controlled to be 3:7; and S8: sequentially send the crosslinked insulation wire core into the three-stage cooling tank.First 80℃ hot water tank cooling 3 min, then 50℃ warm water tank cooling 3 min, finally 25℃ cold water tank cooling 2 min, after cooling, the insulated wire core is transferred into a vacuum drying box, and is set at 60℃ and-0.08Mpa to dry for 1h, and after drying, the insulated wire core is taken out, and the preparation of the insulation layer is completed, and subsequent conventional processes such as a shielding layer and a sheath layer can be directly entered.

[0026] Example 2: Compared with example 1, the difference of the present example is that the amount of modified water-blocking powder is adjusted, specifically as follows: the total amount of modified water-blocking powder added through the side feeding port is 15 parts, among which sodium polyacrylate is 13.5 parts and composite modifier is 1.5 parts, and the rest is consistent with 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 of the present example is that the amount of modified water-blocking powder is adjusted, specifically as follows: the total amount of modified water-blocking powder added through the side feeding port is 20 parts, among which sodium polyacrylate is 19 parts and composite modifier is 1 part, and the rest is consistent with example 1; the purpose is to verify the dispersion stability and water-blocking ability enhancement effect of the water-blocking powder at high dosage.

[0028] Example 4: Compared with example 1, the difference of the present example is that the ratio of KH-550 to polyether modified silicone oil in the composite modifier is adjusted, specifically 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 consistent with example 1; the purpose is to strengthen the compatibility of the composite modifier with the non-polar elastomer, and to verify the interface bonding effect when the flexible modifier is dominant.

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

[0030] Example 6: Compared with example 1, the difference of the present example is that the amount of modified nano-silica is adjusted, specifically as follows: the amount of modified nano-silica added through the side feeding port is 1.0 part, and the rest is consistent with example 1; the purpose is to verify whether the minimum amount of dispersion aid is sufficient to inhibit the agglomeration of water-blocking powder, and to avoid the potential impact of excessive aid on the mechanical properties of the elastomer.

[0031] Example 7: Compared with Example 1, the difference of this example is the amount of modified nano-silica, which is as follows: 1.5 parts of modified nano-silica is added to the side feeding port, and the rest is the same as Example 1; it aims to verify the dispersion effect of water-blocking powder under high dispersant dosage, and to investigate whether the 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 of this comparative example is that the modified water-blocking powder does not add a composite modifier, which is as follows: the modified water-blocking powder is only 16.2 parts of unmodified sodium polyacrylate, without silane coupling agent KH-550 and polyether modified silicone oil, 16.2 parts of unmodified sodium polyacrylate and 1.2 parts of modified nano-silica are directly added to the side feeding port, and the rest is the same as Example 1; it aims to verify the improvement of the composite modifier on the compatibility of sodium polyacrylate and elastomer matrix.

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

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

[0035] Comparative Example 4: Compared with Example 1, the difference of this comparative example is that the insulation layer is a single-layer structure without an inner transition elastomer, which is as follows: S5 inner layer pure elastomer particles are not prepared, S6 double-layer co-extrusion stage only adds blending particles through the outer layer channel, and a single-layer blended water-blocking layer is extruded, and the rest is the same as Example 1; it aims to verify the improvement of gradient structure on the interfacial bonding force.

[0036] Comparative Example 5: This comparative example refers to the preparation method mentioned in the anti-pressure water-blocking layer and the insulation cable with the layer in the publication No. CN120221179A, which prepares a layered water-proof structure, wherein the insulation layer uses pure EPDM with a thickness of 0.6 mm, and the outer layer is wrapped with 20% acrylic salt water-blocking powder to form a 0.2 mm thick water-proof layer; it aims to compare the performance difference between the present application and the existing layered structure.

[0037] Preparation Example 1: According to Figures 2-3As shown, the application also proposes a high-elasticity waterproof cable based on water-blocking powder and elastomer blending, which comprises a single-core twisted conductor layer 1, and a conductor shielding layer 2, an insulation layer 3, an insulation shielding layer 4 and a sheath layer 5 successively wrapped outside the conductor layer 1 from inside to outside, each structural layer is tightly attached and coaxially arranged to form a complete electrical isolation and mechanical protection system, and the specific structural information and functions are as follows: the conductor layer 1 is the current transmission core of the cable, the overall diameter is 4.0 mm, the surface roundness error is ≤0.1 mm, and there is no burr and oxidation layer defect; the conductor shielding layer 2 is tightly wrapped around the outer periphery of the conductor layer 1, the thickness is fixed at 0.5 mm, the volume resistivity is ≤1×10 3 Ω·cm, the surface roughness is ≤0.05 mm, and the adhesion to the conductor layer 1 is ≥95%, which can eliminate the surface electric field distortion of the conductor layer 1, realize the uniform transition of the electric field between the conductor layer 1 and the insulation layer 3, and avoid local electric field concentration to cause insulation failure; the insulation layer 3 is the core insulation and waterproof function layer of the cable, which is tightly wrapped around the outer periphery of the conductor shielding layer 2, and the total thickness is 1.5 mm, which adopts a gradient composite structure design, including an insulation inner layer 6 and an insulation outer layer 7, and the thickness ratio of the two is 3:2, wherein the insulation inner layer 6 is a pure elastomer transition layer, which can relieve the performance mutation of the conductor shielding layer 2 and the insulation outer layer 7, and reduce the interface stress concentration, and the insulation outer layer 7 is tightly wrapped around the outer periphery of the insulation inner layer 6, which can realize self-sealing of the gap after encountering water while ensuring the insulation performance; the insulation shielding layer 4 is tightly wrapped around the outer periphery of the insulation layer 3, and the thickness is 0.5 mm, which is a semi-conductive elastomer layer, and the volume resistivity is ≤1×10 3 Ω·cm, and the adhesion to the insulation layer 3 is ≥95%, the insulation shielding layer 4 can shield the stray electric field outside the insulation layer 3, avoid external interference affecting the electrical performance of the cable, and provide a smooth attachment interface for the sheath layer 5; the sheath layer 5 is the outermost mechanical protection and environmental adaptation layer of the cable, which is tightly wrapped around the outer periphery of the insulation shielding layer 4, and the thickness is 1.0 mm, which can resist external mechanical wear, extrusion and humid environment erosion, protect the structural integrity of the internal functional layers, and prolong the service life of the cable.

[0038] Preparation Example 2: according to Figures 4-5As shown, the application also proposes a high-elasticity waterproof cable based on the blending of water-blocking powder and elastomer, which comprises a multi-core twisted conductor layer 1, and the difference from Preparation Example 1 is that: the conductor layer 1 is a cable core formed by twisting three independent single-core conductors, each single-core conductor has a diameter of 2.0 mm, and after twisting, the overall cable core has a diameter of about 4.5 mm, the surface roundness error of the cable core is ≤0.2 mm, and there is no obvious protrusion or depression, and the twisting gap rate is controlled at 12%-15% to reserve an adaptive space for the subsequent filling layer; in this preparation example, the conductor shielding layer 2, the insulating layer 3 and the insulating shielding layer 4 wrapped outside each single-core conductor are selected to have the same material type and thickness ratio as those in Preparation Example 1, so as to ensure the uniformity of the electric field of each single-core conductor, the high-elasticity recovery capability and the long-acting waterproof performance, and to maintain the same level as the single-core cable in Preparation Example 1, thereby avoiding the attenuation of the core function caused by the multi-core structure; a filling layer 8 and a wrapping layer 9 are newly added between the insulating shielding layer 4 and the sheath layer 5, the filling layer 8 is tightly filled in the triangular gap formed by the twisting of the three single-core conductors, so as to eliminate the gap of the multi-core twisting, avoid the local stress concentration of the wrapping layer 9 and the sheath layer 5 due to the irregularity of the cable core, prevent the abrasion of the insulating layer caused by the displacement of the single-core conductor when the cable is bent, and ensure the stability of the multi-core structure; the wrapping layer 9 is tightly wrapped around the outer periphery of the filled overall cable core, is a polyester non-woven wrapping layer with a fixed thickness of 0.4 mm, forms a transition interface between the filling layer 8 and the subsequent sheath layer 5, avoids the generation of bubbles due to the uneven surface of the filling layer 8 when the sheath layer 5 is extruded and wrapped, and can also buffer the deformation stress between the sheath layer 5 and the internal single-core conductor, thereby reducing the interface abrasion in long-term dynamic service.

[0039] Performance test: in order to verify the core performance of the insulating layer of the high-elasticity waterproof cable based on the blending of water-blocking powder and elastomer, the complete insulating wire core prepared in Examples 1-7 and Comparative Examples 1-4 is taken as the test object, systematic tests are carried out around the interface bonding force, the elastic performance, the waterproof performance and the insulating performance, and the following is the specific test scheme.

[0040] Test Example 1: This test example focuses on the interface bonding reliability of the insulating layer and the conductor shielding layer. The interlayer separation resistance is evaluated through static strength test and dynamic stability test. The specific test items and process are as follows: according to GB / T2951.31-2008 "Cables and optical cables Insulation and sheath materials General test methods Part 31: Polyolefin insulation and sheath materials Environmental stress cracking resistance test, Melt flow rate test and Peel strength test", a 100mm long insulating core sample is cut from each sample, the insulating layer and the conductor shielding layer at one end are carefully peeled off using a knife, then the conductor shielding layer is fixed on the lower clamp of the universal tensile testing machine, the insulating layer is fixed on the upper clamp, the tensile speed is set to 50mm / min, the tensile testing machine is started for peel test, the tensile force change is recorded in real time during the test, the average peel force in the stable stage is taken, the peel strength is calculated combined with the sample width; the insulating core is processed into a cylindrical sample with a diameter of 10mm and a height of 8mm, ensuring that the interface between the conductor shielding layer and the insulating layer is completely exposed and perpendicular to the sample axis, a special shear clamp is used to fix the sample, the shear force direction is parallel to the interface, the shear speed of the tensile testing machine is set to 10mm / min, the shear force is applied until the interface is damaged, the maximum shear force at the time of damage is recorded, and the shear strength is calculated combined with the shear area; a 500mm long insulating core sample is cut, placed on a dynamic bending testing machine, set the bending radius to 20mm, the bending angle to ±90°, the cycle frequency to 1 / s, and complete 1000 dynamic bending cycles; after the cycle is completed, the peel strength is measured again, and the peel strength retention rate is calculated according to the peel strength, reflecting the degree of decay of the interface bonding force after service.

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

[0042]

[0043] According to the data in Table 1, the interface bonding performance of the insulating layer and the conductor shielding layer of Examples 1-7 is significantly better than that of Comparative Examples 1-5, which is specifically embodied in that: the peeling strength of Examples 1-7 is 1.5-2.0 N / mm, the shear strength is 2.8-3.5 MPa, and the peeling strength retention rate after 1000 dynamic bending cycles is 79-88%; while the peeling 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 cycles is only 48-60%, the performance gap is significant; Comparative Example 1 does not add a composite modifier, the polarity difference between sodium polyacrylate and the elastomer matrix cannot be eliminated, and its peeling strength is only 44% of that of Example 1, proving that the composite modifier can effectively improve the interface bonding state of the water-blocking powder and the elastomer by condensation of amino and hydroxyl groups with non-polar segments; Comparative Example 4 does not set the inner layer transition elastomer, and there is no performance buffer interface between the insulating layer and the conductor shielding layer, and its shear strength is 50% lower than that of Example 1, proving the role of gradient structure in relieving interface stress and avoiding interlayer bonding force attenuation caused by performance mutation; Comparative Example 5 uses the layered structure of the prior art, and the peeling strength retention rate after dynamic cycle is only 48%, which is much lower than the 85% of Example 1, confirming that the water-blocking powder and elastomer blending design of the application can effectively solve the interlayer separation problem of the layered structure in dynamic service.

[0044] Test Example 2: This test example is around the deformation recovery and mechanical bearing capacity of the insulating layer, and evaluates the elasticity and strength synergy of the insulating layer through tensile tests, and the specific test items and processes are as follows: according to GB / T528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized or Thermoplastic Rubber", the core evaluation of the deformation capacity of the insulating layer is carried out, the insulating layer is peeled off from the core, and a dumbbell-shaped sample is processed, the sample thickness is consistent with the actual thickness of the insulating layer, and is uniformly 0.6 mm, the gauge length is 25 mm and the width is 4 mm, the sample is installed in the upper and lower clamps of the universal tensile testing machine, ensuring that the sample axis is consistent with the tensile direction, the tensile speed is set to 200 mm / min, after starting the test, the elongation of the gauge length is recorded in real time until the sample breaks, and the breaking elongation is calculated according to the elongation of the gauge length at the time of breaking; the dumbbell-shaped sample with the same specification as the breaking elongation test is used, the sample is stretched to 100% set deformation, i.e. the gauge length is stretched from 25 mm to 50 mm, and the deformation state is maintained for 10 min to simulate a long-term stress scenario; then the tension is released, and the sample is naturally recovered at room temperature for 10 min, the length of the recovered gauge length is measured, and the elastic recovery rate is calculated according to the permanent deformation; the dumbbell-shaped sample is installed in the universal tensile testing machine, and a tensile force is applied at a speed of 200 mm / min until the sample breaks, and the maximum tensile force value at the time of sample breaking is recorded, and the tensile strength is calculated combined with the effective cross-sectional area of the sample.

[0045] The specific test results are shown in Table 2:

[0046]

[0047] As can be seen from the data in Table 2, the elastic properties of Examples 1-7 as a whole meet the high-elasticity design target and are superior to the comparative examples: the elongation at break of Examples 1-7 is 345-380%, the elastic recovery rate at 100% 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; Comparative Example 1, which uses unmodified sodium polyacrylate, destroys the continuous phase structure of the elastomer matrix due to particle agglomeration, and the elongation at break is 23% lower than that of Example 1, and the tensile strength is only 71% of that of Example 1.

[0048] Test Example 3: This test example comprehensively evaluates the waterproof reliability of the insulation layer from three dimensions of short-term water resistance, long-term weather-resistant water resistance, and longitudinal water permeability resistance. The specific test items and processes are as follows: cut the insulation core sample to a length of 500 mm, seal both ends of the sample, immerse the sealed sample in deionized water at 25°C, ensure that the sample is immersed to a depth of 100 mm, and at the same time apply a hydrostatic pressure of 0.2 MPa to the water through a water pressure device to simulate the water pressure scenario in a humid environment. Measure the insulation resistance of the sample before and after 24 hours of immersion using a high resistance meter, and calculate the insulation resistance drop rate based on the two resistance values. The lower the drop rate, the better the short-term water resistance performance. Using the same size insulation core sample as the short-term water resistance test, first perform 50 dry-wet cycle treatments, 8 hours of 25°C deionized water immersion, and 16 hours of 60°C air drying, to simulate the alternating environment of humidity and dryness in actual service. After the cycle is completed, measure the insulation resistance at this time according to the same method as the short-term water resistance test, and calculate the water resistance retention rate to reflect the degree of attenuation of the waterproof performance under long-term environmental action. Cut the insulation core sample to a length of 1000 mm, seal one end of the sample with epoxy resin, and connect the other end to the water pressure supply device through a sealed joint to apply a water pressure of 0.3 MPa to the inside of the sample. At the same time, observe whether water seeps out of the sealed end of the sample, record the time it takes for water to penetrate from the water inlet end of the sample to the sealed end, and calculate the longitudinal water permeability rate based on the water permeation time.

[0049] The specific test results are shown in Table 3:

[0050]

[0051] 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.

[0052] 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.

[0053] The specific test results are shown in Table 4:

[0054]

[0055] The data in Table 4 shows that the insulation performance of Examples 1-7 meets the safe operation requirements of low-voltage cables and is superior to the comparative examples: the volume resistivity of Examples 1-7 is 1.5×10 15 -3.1×10 15 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 13 -1.5×10 14 Ω·cm, the breakdown field strength is only 14.9-17.8 kV / mm, and the dielectric loss tangent is only 0.0076-0.0103; Comparative Example 1 has only 3.3% of the volume resistivity of Example 1, a 26% decrease in breakdown field strength, because the sodium polyacrylate is not modified and the agglomerated particles form local conductive channels, proving that composite modification can eliminate the polarity defects of the water-blocking powder and avoid degradation of insulation performance; the insulation performance of Examples 6 and 7 is not significantly different from that of Example 1, indicating that within the 1-1.5 part usage range, the modified nanosilica does not affect the electrical performance of the insulation layer while ensuring dispersion effect.

[0056] The technical scope of the present application is not limited to the content in the above description, and those skilled in the art can make various modifications and changes to the above examples without departing from the technical idea of the present application, and these modifications and changes should all be within the protection scope of the present application.

Claims

1. A highly flexible water blocking cable based on a blend of water blocking powder and elastomer, characterized in that, The cable comprises a conductor layer, a conductor shielding layer, an insulation layer, an insulation shielding layer and a sheath layer from inside to outside, 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 blended layer of modified water-blocking powder and an elastomer matrix; the composition of the insulation outer layer comprises, by weight fraction, 70-80 parts of an elastomer matrix, 0.5-1.0 parts of a crosslinking regulator, 1-2 parts of a softener, 1.5-2.0 parts of a crosslinking agent, 0.5-1.0 parts of a composite antioxidant, 15-20 parts of modified water-blocking powder and 1.0-1.5 parts of blended particles of nano-silicon dioxide modified by silane coupling agent KH-570, and the blending and homogenization section adopts ultrasonic dispersion process; the elastomer matrix is composed of 90-95% of ethylene-propylene-diene rubber and 5-10% of ethylene-octene copolymer; the modified water-blocking powder is composed of 90-95% of sodium polyacrylate and 5-10% of a composite modifier, the composite modifier is a mixture of silane coupling agent KH-550 and polyether modified silicone oil, and the mass ratio of the two is 3:7-6:4; the composition of the insulation inner layer comprises, by weight fraction, 75 parts of ethylene-propylene-diene rubber, 1.8 parts of a crosslinking agent, 0.6 parts of a composite antioxidant and 2.5 parts of the blended particles, and the insulation inner layer and the insulation outer layer are synchronously extruded by a double-layer co-extrusion die head.

2. A high flexibility water blocking cable based on blend of water blocking powder and elastomer as claimed in claim 1, wherein: The crosslinking regulator is triallyl isocyanurate, the softener is liquid paraffin, and the crosslinking agent is dicumyl peroxide.

3. A high flexibility water blocking cable based on blend of water blocking powder and elastomer as claimed in claim 1, wherein: 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 for improving the winding compatibility with the elastomer matrix.

4. A high flexibility water blocking cable based on blend of water blocking powder and elastomer as claimed in claim 1, wherein: The amount of the silane coupling agent KH-570 is 5% of the mass of the nano-silicon dioxide.

5. A high flexibility water blocking cable based on blend of water blocking powder and elastomer as claimed in claim 1, wherein: The composite antioxidant is composed of 2,6-di-tert-butyl-p-cresol and antioxidant 1010 at a mass ratio of 1:

1. ​ 6. A high flexibility water blocking cable based on blend of water blocking powder and elastomer as claimed in claim 1, wherein: When the cable core is formed by twisting a plurality of conductors, the insulation shielding layer and the sheath layer further comprise a filling layer and a wrapping layer.

7. A high flexibility water blocking cable based on blend of water blocking powder and elastomer as claimed in claim 1, wherein the said cable is characterized by: The preparation steps of the insulation layer include: S1: drying sodium polyacrylate at 105 DEG C, -0.09 MPa for 4 h, mixing with the composite modifier diluted by 3 times of anhydrous ethanol under nitrogen protection at 100 DEG C, then adding modified nano-silica and stirring uniformly, and obtaining modified water-blocking powder after cooling; S2: starting a double screw extruder, controlling the temperature of homogenization section at 110 DEG C, first adding ethylene-propylene-diene rubber, ethylene-octene copolymer, triallyl isocyanurate and liquid paraffin for melt mixing, then adding the modified water-blocking powder, starting ultrasonic dispersion after melt mixing, and extruding and granulating after drying at 80 DEG C for 2 h, 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 extruding and granulating after melt mixing, to obtain an insulation inner layer material; S4: starting a double-layer co-extruder head, feeding the insulation inner layer material and insulation outer layer blended particles into the inner and outer flow channels respectively, and synchronously extruding and coating on the conductor shielding layer; S5: feeding the extruded wire core into a nitrogen protection steam crosslinking pipe, controlling the volume ratio of nitrogen and steam at 3:7 at 170 DEG C and 0.8 MPa, crosslinking for 18 min, then gradient water cooling, and finally vacuum drying at 60 DEG C and -0.08 MPa for 1 h, to form the insulation layer.

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