Flexible photovoltaic cable and method for its production

Abstract

The application belongs to the technical field of cable preparation, and particularly relates to a flexible photovoltaic cable and a preparation method thereof, which comprises the following steps: uniformly mixing polycaprolactam, modified silicon dioxide, PP-g-MAH and polypropylene to obtain inner cable material; uniformly mixing modified silicon dioxide, EVA-g-MAH, EVA, polyether TPU and polyvinylidene fluoride to obtain outer cable material; feeding the inner cable material and the outer cable material into a double-layer co-extrusion machine group, and extruding concentrically with a cable core to obtain the flexible photovoltaic cable after cooling; and the modified silicon dioxide is obtained by sequentially treating silicon dioxide with GPS hydrolysis liquid and DTMS hydrolysis liquid. The application can inhibit the hydrolysis of polycaprolactam and improve the service life of the flexible photovoltaic cable in a humid environment.

Description

Technical Field

[0001] This invention belongs to the field of cable manufacturing technology, and particularly relates to a flexible photovoltaic cable and its manufacturing method. Background Technology

[0002] In solar photovoltaic (PV) power generation systems, PV modules, inverters, combiner boxes, and other electrical equipment are electrically connected via PV cables. These cables are exposed outdoors for extended periods, thus requiring excellent waterproofing to ensure system safety. Current technologies often employ methods such as wrapping the PV cables with water-blocking tape to create a water-blocking layer. However, this method is ineffective, allowing moisture to easily seep into the gap between the water-blocking layer and the cable. This results in the PV cables being constantly submerged in water, accelerating their aging and shortening their lifespan.

[0003] Chinese patent document CN117153470B discloses a waterproof and anti-aging photovoltaic cable and its preparation method, including the following steps: extruding a blend of polypropylene, polycaprolactam, and branched glass fiber to obtain a waterproof layer; preparing a protective coating using branched glass fiber, bisphenol A diglycidyl ether, polyetheramine, polydimethylsiloxane, and an amine curing agent; applying the protective coating to the surface of the waterproof layer and curing it to obtain a protective sheath, thereby preparing a waterproof and anti-aging photovoltaic cable. In the above cable, by coating the waterproof layer with a hydrophobic protective coating, water penetration can be inhibited to a certain extent. However, since the waterproof layer includes polypropylene, polycaprolactam, and branched glass fiber, during long-term use in a humid environment, the amide bonds in the polycaprolactam are prone to hydrolysis with water molecules, leading to molecular chain breakage, decreased mechanical properties, and ultimately, cracking of the waterproof layer, affecting the cable's service life. Summary of the Invention

[0004] This invention provides a flexible photovoltaic cable and its preparation method, which inhibits the hydrolysis of polycaprolactam and improves the service life of the flexible photovoltaic cable in humid environments.

[0005] To solve the above problems, the present invention adopts the following technical solution:

[0006] A method for preparing a flexible photovoltaic cable includes the following steps:

[0007] S1. Mix polycaprolactam, modified silica, PP-g-MAH, and polypropylene to obtain the inner cable material;

[0008] S2. Mix modified silica, EVA-g-MAH, EVA, polyether-type TPU, and polyvinylidene fluoride to obtain the outer cable material;

[0009] S3, the inner layer cable material and the outer layer cable material are sent into a double-layer co-extrusion machine, and are concentrically extruded with the cable core under the conditions that the extrusion temperature is 230-235 DEG C and the double-screw rotation speed is 400-500 rpm, and the flexible photovoltaic cable is obtained after cooling;

[0010] The modified silicon dioxide is obtained by sequentially treating silicon dioxide with GPS hydrolysis liquid and DTMS hydrolysis liquid.

[0011] The inner layer cable material and the outer layer cable material are extruded through the double-layer co-extrusion machine, and the flexible photovoltaic cable is obtained by forming the base layer coated outside the cable core and the protective layer coated outside the base layer. The inner layer cable material and the outer layer cable material both contain modified silicon dioxide. The surface of the modified silicon dioxide contains epoxy groups and long-chain alkyl groups due to the modification treatment of GPS hydrolysis liquid and DTMS hydrolysis liquid. In the process of melting and extrusion of the inner layer cable material, the ring-opening reaction occurs between the epoxy groups on the surface of the modified silicon dioxide and the terminal amino groups of polycaprolactam, so as to improve the compactness of the base layer and inhibit the penetration of moisture. Meanwhile, the long-chain alkyl groups on the surface of the modified silicon dioxide have hydrophobicity, which effectively inhibits the hydrolysis of amide bonds in polycaprolactam, avoids the cracking of the base layer in the bending process, improves the insulation performance of the flexible cable, and further improves the service life of the flexible photovoltaic cable in a humid environment. The protective layer contains polyvinylidene fluoride with excellent waterproof performance, which inhibits the contact between the base layer and external moisture, and further improves the service life of the flexible photovoltaic cable in a humid environment.

[0012] The ring-opening reaction occurs between the epoxy groups of the modified silicon dioxide in the outer layer cable material and the terminal amino groups of polycaprolactam in the inner layer cable material in the high-temperature molten state in the initial cooling stage after the co-extrusion of the inner layer cable material and the outer layer cable material at 230-235 DEG C, so that the interface between the base layer and the protective layer is fused, the interface defects are reduced, the moisture is prevented from penetrating through the interface defects and contacting the base layer, the cracking of the base layer in a humid environment is inhibited when used for a long time, and the service life of the flexible photovoltaic cable in a humid environment is further improved.

[0013] Further, in the step S1, the modified silicon dioxide, PP-g-MAH and lubricant are uniformly mixed and sent into an extruder for extrusion, and the extrusion temperature is 160-170 DEG C. After cooling and granulation, the PP-based master batch is obtained. The PP-based master batch, polycaprolactam and polypropylene are uniformly mixed to obtain the inner layer cable material.

[0014] PP-g-MAH can improve the compatibility between polycaprolactam and polypropylene, avoid phase separation of the inner cable material during melt extrusion; polycaprolactam has excellent wear resistance, and polypropylene has good flexibility and fatigue resistance, and the two are synergistic, which gives the base layer good bending resistance, avoids cracking of the base layer during bending, and ensures that the flexible photovoltaic cable has good insulation performance.

[0015] Further, in the step S2, the modified silica, EVA-g-MAH and lubricant are mixed and sent into an extruder for extrusion at an extrusion temperature of 180-190 DEG C, and after cooling, granulation and drying, an EVA system functional masterbatch is obtained; the EVA system functional masterbatch, EVA, polyether TPU and polyvinylidene fluoride are mixed to obtain an outer cable material.

[0016] EVA-g-MAH and EVA improve the compatibility between polyvinylidene fluoride and polyether TPU, avoid phase separation of the outer cable material during melt extrusion; polyvinylidene fluoride has excellent waterproofness, and EVA and polyether TPU have good flexibility, so that the protective layer has good bending resistance while being waterproof, can deform synchronously with the cable core and the base layer without cracking or interfacial peeling, prevents the base layer from contacting with external moisture, and inhibits the hydrolytic cleavage of amide bonds in the base layer.

[0017] The modified silica is dispersed in PP-g-MAH to prepare a PP-based masterbatch, and the modified silica is dispersed in EVA-g-MAH to prepare an EVA system functional masterbatch, and then the two masterbatches are dispersed in the inner cable material and the outer cable material respectively, so that the agglomeration of the modified silica is effectively avoided, and the dispersion uniformity of the modified silica in the base layer and the protective layer is improved.

[0018] Further, the outer cable material further comprises TMPTGE and EMI-24.

[0019] TMPTGE, EMI-24 and polyether TPU have good compatibility, which is beneficial to the uniform dispersion of TMPTGE and EMI-24 in the outer cable material; when the outer cable material is extruded at 230-235 DEG C, the epoxy group of TMPTGE reacts with the chain end hydroxyl group of polyether TPU under the catalysis of EMI-24 to form a crosslinked network, improve the compactness of the protective layer, inhibit the migration of the modified silica, and at the same time, the epoxy group of TMPTGE can undergo ring-opening reaction with the terminal amino group of polycaprolactam in the inner cable material, further improving the interfacial bonding force between the protective layer and the base layer.

[0020] Further, the modified silica is prepared by dispersing silica in anhydrous ethanol, adding GPS hydrolysate, stirring at 500-550 rpm for 1.5-2.5 h, dispersing in anhydrous ethanol after filtration and anhydrous ethanol washing, adding DTMS hydrolysate, stirring at 450-500 rpm for 2-3 h, and obtaining the modified silica after filtration, tert-butyl alcohol solution washing and freeze drying.

[0021] The step-by-step modification of silica with GPS hydrolysate and DTMS hydrolysate in sequence can control the grafting density of epoxy groups and long-chain alkyl groups on the surface of silica respectively, and realize the synergistic introduction of epoxy groups and long-chain alkyl groups.

[0022] Further, the temperature of freeze drying is -40--30℃, the pressure is 10-20 Pa, and the drying time is 24-28 h.

[0023] The preparation of modified silica by freeze drying can better retain the grafted epoxy groups and long-chain alkyl groups on the surface of modified silica, and avoid the agglomeration of modified silica during drying.

[0024] Further, the GPS hydrolysate is prepared by mixing anhydrous ethanol, GPS and acetic acid solution, adding deionized water under continuous stirring, and stirring at 300-400 rpm for 1.5-2.5 h.

[0025] Further, the DTMS hydrolysate is prepared by mixing anhydrous ethanol, DTMS and acetic acid solution, slowly adding deionized water under continuous stirring, and stirring at 300-400 rpm for 3-4 h.

[0026] A flexible photovoltaic cable is prepared by the above-mentioned method for preparing a flexible photovoltaic cable, comprising a cable core, an inner cable material and an outer cable material, the inner cable material comprising the following raw materials in parts by mass: PP-based masterbatch 14-17 parts, polycaprolactam 155-165 parts, polypropylene 90-110 parts; the outer cable material comprising the following raw materials in parts by mass: EVA system functional masterbatch 10-14 parts, EVA 12-16 parts, polyether TPU 100-109 parts, polyvinylidene fluoride 80-90 parts, TMPTGE 0-5 parts, EMI-24 0-0.2 parts; the PP-based masterbatch comprising the following raw materials in parts by mass: modified silica 18-22 parts, PP-g-MAH 72-80 parts, lubricant 0.3-0.4 parts; the EVA system functional masterbatch comprising the following raw materials in parts by mass: modified silica 18-23 parts, EVA-g-MAH 68-75 parts, lubricant 0.3-0.4 parts; the lubricant is stearic acid; and the material of the cable core is pure copper or tin-plated copper.

[0027] Further, the modified silica comprises the following mass parts of raw materials: silica 45-55 parts, GPS hydrolysate 20-30 parts, DTMS hydrolysate 20-30 parts; the GPS hydrolysate comprises the following mass parts of raw materials: anhydrous ethanol 190-210 parts, GPS 20-25 parts, 3-4wt% acetic acid solution 3-5 parts, deionized water 8-10 parts; the DTMS hydrolysate comprises the following mass parts of raw materials: anhydrous ethanol 195-215 parts, DTMS 25-27 parts, 4-5wt% acetic acid solution 5-7 parts, deionized water 10-13 parts.

[0028] The beneficial effects of the present application are:

[0029] The cable comprises a cable core, a base layer covering the cable core, and a protective layer covering the base layer, in the base layer, the epoxy groups on the surface of the modified silica and the terminal amino groups of the polycaprolactam undergo ring-opening reaction, the base layer has high compactness, at the same time, the long-chain alkyl groups on the surface of the modified silica have hydrophobicity, preventing moisture from penetrating, effectively inhibiting the hydrolysis of the amide bond of the polycaprolactam, avoiding the cracking of the base layer, and improving the service life of the flexible photovoltaic cable in a humid environment; the polyvinylidene fluoride in the protective layer has good water resistance, the epoxy groups on the surface of the modified silica in the protective layer and the terminal amino groups of the polycaprolactam in the base layer undergo ring-opening reaction, reducing the interfacial defects between the layers, improving the interfacial bonding force, and further inhibiting the hydrolysis of the polycaprolactam. DETAILED DESCRIPTION

[0030] Preparation Example One

[0031] Mix 200 g of anhydrous ethanol, 25 g of GPS (γ-glycidoxypropyltrimethoxysilane) and 3 g of 3 wt% acetic acid solution, stir at 400 rpm for 15 min, add 9 g of deionized water at a speed of 0.2 g / min under the condition of stirring at 450 rpm, stir at 300 rpm for 2 h, to obtain a GPS hydrolyzate; mix 200 g of anhydrous ethanol, 27 g of DTMS (dodecyltrimethoxysilane) and 5 g of 4 wt% acetic acid solution, stir at 400 rpm for 15 min, add 12 g of deionized water at a speed of 0.2 g / min under the condition of stirring at 450 rpm, stir at 300 rpm for 3 h, to obtain a DTMS hydrolyzate; add 50 g of silica with a particle size of 10 nm into 300 g of anhydrous ethanol, ultrasonic dispersion for 20 min, add 20 g of GPS hydrolyzate, stir at 500 rpm for 2 h, filter, wash with anhydrous ethanol, add 300 g of anhydrous ethanol, stir at 700 rpm for 20 min, add 20 g of DTMS hydrolyzate, stir at 500 rpm for 2 h, filter, wash with 50 wt% tert-butyl alcohol solution, place in a freeze-drying box, adjust the pressure to 20 Pa and the temperature to -30°C and maintain for 24 h, to obtain modified silica.

[0032] Preparation Example Two

[0033] Mix 190 g of anhydrous ethanol, 20 g of GPS and 4 g of 4 wt% acetic acid solution, stir at 400 rpm for 15 min, add 8 g of deionized water at a speed of 0.2 g / min under the condition of stirring at 450 rpm, stir at 350 rpm for 2.5 h, to obtain a GPS hydrolyzate; mix 195 g of anhydrous ethanol, 25 g of DTMS and 6 g of 5 wt% acetic acid solution, stir at 400 rpm for 15 min, add 10 g of deionized water at a speed of 0.2 g / min under the condition of stirring at 450 rpm, stir at 400 rpm for 3.5 h, to obtain a DTMS hydrolyzate; add 45 g of silica with a particle size of 10 nm into 300 g of anhydrous ethanol, ultrasonic dispersion for 20 min, add 25 g of GPS hydrolyzate, stir at 525 rpm for 2.5 h, filter, wash with anhydrous ethanol, add 300 g of anhydrous ethanol, stir at 700 rpm for 20 min, add 25 g of DTMS hydrolyzate, stir at 450 rpm for 3 h, filter, wash with 50 wt% tert-butyl alcohol solution, place in a freeze-drying box, adjust the pressure to 10 Pa and the temperature to -35°C and maintain for 28 h, to obtain modified silica.

[0034] Preparation Example Three

[0035] Mix 210 g of anhydrous ethanol, 22 g of GPS and 5 g of 3.5 wt% acetic acid solution, stir at 400 rpm for 15 min, add 10 g of deionized water at a speed of 0.2 g / min under the condition of stirring at 450 rpm, stir at 400 rpm for 1.5 h to obtain a GPS hydrolysate; mix 215 g of anhydrous ethanol, 26 g of DTMS and 7 g of 4.5 wt% acetic acid solution, stir at 400 rpm for 15 min, add 13 g of deionized water at a speed of 0.2 g / min under the condition of stirring at 450 rpm, stir at 350 rpm for 4 h to obtain a DTMS hydrolysate; add 55 g of silica with a particle size of 10 nm into 300 g of anhydrous ethanol, ultrasonic dispersion for 20 min, add 30 g of GPS hydrolysate, stir at 550 rpm for 1.5 h, filter, wash with anhydrous ethanol, add 300 g of anhydrous ethanol, stir at 700 rpm for 20 min, add 30 g of DTMS hydrolysate, stir at 475 rpm for 2.5 h, filter, wash with 50 wt% tert-butyl alcohol solution, place in a freeze dryer, adjust the pressure to 15 Pa and the temperature to -40℃ and maintain for 26 h to obtain modified silica.

[0036] Example One

[0037] Mix 20 g of modified silica, 75 g of PP-g-MAH and 0.3 g of stearic acid, stir at 750 rpm for 5 min, feed into a twin-screw extruder for extrusion, the extrusion temperature is 165℃, the rotation speed of the twin screw is 400 rpm, the extrudate is cooled to room temperature by air cooling and then fed into a granulator for granulation to obtain a PP-based masterbatch; mix 20 g of modified silica, 70 g of EVA-g-MAH and 0.3 g of stearic acid, stir at 750 rpm for 5 min, feed into a twin-screw extruder for extrusion, the extrusion temperature is 185℃, the rotation speed of the twin screw is 400 rpm, the extrudate is cooled by cooling water with a temperature of 45℃ and then fed into a granulator for granulation, dry in an oven at 55℃ for 5 h to obtain an EVA system functional masterbatch; mix 10 g of the EVA system functional masterbatch, 12 g of EVA, 100 g of polyether TPU, 85 g of polyvinylidene fluoride, 4 g of TMPTGE (trimethylolpropane triglycidyl ether) and 0.2 g of EMI-24 (2-ethyl-4-methylimidazole), stir at 700 rpm for 15 min to obtain an outer layer cable material.

[0038] The inner layer cable material and the outer layer cable material are respectively added into two independent hoppers of a double-layer co-extrusion machine, a pure copper core material is led out by a wire drawing device and located at the center of a concentric die, extruded under the condition of an extrusion temperature of 235℃ and a rotation speed of the twin screw of 400 rpm, cooled to room temperature to obtain a flexible photovoltaic cable.

[0039] The modified silica used in this example was prepared by Preparation Example One.

[0040] Example Two

[0041] The modified silica, PP-g-MAH, and stearic acid were mixed, stirred at 750 rpm for 5 min, and fed into a twin-screw extruder for extrusion. The extrusion temperature was 165°C, the twin-screw speed was 400 rpm, and the extrudate was cooled to room temperature by air cooling and then fed into a pelletizer for pelletization to obtain the PP-based masterbatch. The PP-based masterbatch, polycaprolactam, and polypropylene were mixed, stirred at 700 rpm for 15 min, to obtain the inner layer cable material. The modified silica, EVA-g-MAH, and stearic acid were mixed, stirred at 750 rpm for 5 min, and fed into a twin-screw extruder for extrusion. The extrusion temperature was 188°C, the twin-screw speed was 400 rpm, and the extrudate was cooled by cooling water at a temperature of 45°C and then fed into a pelletizer for pelletization and dried in an oven at 55°C for 5 h to obtain the EVA system functional masterbatch. The EVA system functional masterbatch, EVA, polyether TPU, polyvinylidene fluoride, and TMPTGE were mixed, stirred at 700 rpm for 15 min, to obtain the outer layer cable material.

[0042] The inner layer cable material and the outer layer cable material were respectively added to two independent hoppers of a double-layer co-extrusion machine set. A tinned copper material cable core was drawn out by a wire drawing device and located at the center of a concentric die. The extrusion temperature was 230°C, the twin-screw speed was 450 rpm, and the extrudate was cooled to room temperature to obtain a flexible photovoltaic cable.

[0043] The modified silica used in this example was prepared by Preparation Example One.

[0044] Example Three

[0045] Mix 18 g of modified silica, 80 g of PP-g-MAH, and 0.3 g of stearic acid, stir at 750 rpm for 5 min, and then feed into a double screw extruder for extrusion, with an extrusion temperature of 168°C and a double screw speed of 400 rpm; the extrudate is cooled to room temperature by air cooling, and then fed into a granulator for granulation to obtain a PP-based masterbatch; mix 14 g of the PP-based masterbatch, 165 g of polycaprolactam, and 105 g of polypropylene, stir at 700 rpm for 15 min, to obtain an inner layer cable material; mix 23 g of modified silica, 75 g of EVA-g-MAH, and 0.3 g of stearic acid, stir at 750 rpm for 5 min, and then feed into a double screw extruder for extrusion, with an extrusion temperature of 190°C and a double screw speed of 400 rpm; the extrudate is cooled by cooling water at a temperature of 45°C, and then fed into a granulator for granulation; the granules are dried in an oven at 55°C for 5 h, to obtain an EVA system functional masterbatch; mix 14 g of the EVA system functional masterbatch, 16 g of EVA, 109 g of polyether TPU, 90 g of polyvinylidene fluoride, 5 g of TMPTGE, and 0.1 g of EMI-24, stir at 700 rpm for 15 min, to obtain an outer layer cable material.

[0046] The inner layer cable material and the outer layer cable material are respectively added into two independent hoppers of a double-layer co-extrusion machine; a cable core made of pure copper is led out by a wire drawing device and located at the center of a concentric die; the cable core is extruded at an extrusion temperature of 233°C and a double screw speed of 450 rpm, and then cooled to room temperature, to obtain a flexible photovoltaic cable.

[0047] The modified silica used in this example is prepared according to Preparation Example Two.

[0048] Example Four

[0049] Mix 18 g of modified silica, 75 g of PP-g-MAH, and 0.4 g of stearic acid, stir at 750 rpm for 5 min, and then feed into a double screw extruder for extrusion, with an extrusion temperature of 168°C and a double screw speed of 400 rpm; the extrudate is cooled to room temperature by air cooling, and then fed into a granulator for granulation to obtain a PP-based masterbatch; mix 17 g of the PP-based masterbatch, 165 g of polycaprolactam, and 110 g of polypropylene, stir at 700 rpm for 15 min, to obtain an inner layer cable material; mix 19 g of modified silica, 68 g of EVA-g-MAH, and 0.4 g of stearic acid, stir at 750 rpm for 5 min, and then feed into a double screw extruder for extrusion, with an extrusion temperature of 185°C and a double screw speed of 400 rpm; the extrudate is cooled by cooling water at a temperature of 45°C, and then fed into a granulator for granulation; the granules are dried in an oven at 55°C for 5 h, to obtain an EVA system functional masterbatch; mix 11 g of the EVA system functional masterbatch, 13 g of EVA, 103 g of polyether TPU, 80 g of polyvinylidene fluoride, 4 g of TMPTGE, and 0.1 g of EMI-24, stir at 700 rpm for 15 min, to obtain an outer layer cable material.

[0050] The inner layer cable material and the outer layer cable material are respectively added into two independent hoppers of a double-layer co-extrusion machine, the cable core of tinned copper material is led out by a wire drawing device and located at the center of a concentric die, and then extruded under the conditions of an extrusion temperature of 230℃ and a double screw rotation speed of 500rpm, and cooled to room temperature to obtain the flexible photovoltaic cable.

[0051] The modified silicon dioxide used in this example is prepared by Preparation Example Two.

[0052] Example Five

[0053] 22g of modified silicon dioxide, 72g of PP-g-MAH and 0.4g of stearic acid are mixed, stirred at 750rpm for 5min, and then fed into a double screw extruder for extrusion, the extrusion temperature is 170℃, the double screw rotation speed is 400rpm, the extrudate is cooled to room temperature by air cooling, and then fed into a granulator for granulation to obtain the PP-based masterbatch. 17g of the PP-based masterbatch, 160g of polycaprolactam and 105g of polypropylene are mixed, stirred at 700rpm for 15min to obtain the inner layer cable material. 18g of modified silicon dioxide, 73g of EVA-g-MAH and 0.3g of stearic acid are mixed, stirred at 750rpm for 5min, and then fed into a double screw extruder for extrusion, the extrusion temperature is 183℃, the double screw rotation speed is 400rpm, the extrudate is cooled by cooling water with a temperature of 45℃, and then fed into a granulator for granulation, and dried in an oven at 55℃ for 5h to obtain the EVA system functional masterbatch. 10g of the EVA system functional masterbatch, 16g of EVA, 105g of polyether TPU and 85g of polyvinylidene fluoride are mixed, stirred at 700rpm for 15min to obtain the outer layer cable material.

[0054] The inner layer cable material and the outer layer cable material are respectively added into two independent hoppers of a double-layer co-extrusion machine, the cable core of tinned copper material is led out by a wire drawing device and located at the center of a concentric die, and then extruded under the conditions of an extrusion temperature of 230℃ and a double screw rotation speed of 500rpm, and cooled to room temperature to obtain the flexible photovoltaic cable.

[0055] The modified silicon dioxide used in this example is prepared by Preparation Example Three.

[0056] Example Six

[0057] Mix 22 g modified silica, 72 g PP-g-MAH, 0.4 g stearic acid, stir at 750 rpm for 5 min, feed into a twin-screw extruder for extrusion, the extrusion temperature is 170℃, the rotation speed of the twin screw is 400 rpm, the extrudate is cooled to room temperature by air cooling, then fed into a granulator for granulation, to obtain PP-based masterbatch; mix 18 g modified silica, 73 g EVA-g-MAH, 0.3 g stearic acid, stir at 750 rpm for 5 min, feed into a twin-screw extruder for extrusion, the extrusion temperature is 183℃, the rotation speed of the twin screw is 400 rpm, the extrudate is cooled by cooling water at a temperature of 45℃, then fed into a granulator for granulation, and dried in an oven at 55℃ for 5 h, to obtain EVA system functional masterbatch; mix 10 g EVA system functional masterbatch, 16 g EVA, 105 g polyether TPU, 85 g polyvinylidene fluoride, 5 g TMPTGE, 0.2 g EMI-24, stir at 700 rpm for 15 min, to obtain outer layer cable material.

[0058] The inner layer cable material and the outer layer cable material are respectively added into two independent hoppers of a double-layer co-extrusion machine, a pure copper core material is led out by a wire drawing device and located at the center of a concentric die, and extruded under the condition that the extrusion temperature is 233℃ and the rotation speed of the twin screw is 500 rpm, to obtain a flexible photovoltaic cable after cooling to room temperature.

[0059] The modified silica used in this example is prepared by Preparation Example Three.

[0060] The present application also sets up a comparative example and carries out related tests.

[0061] Comparative Example One

[0062] The difference between this comparative example and Example Six is that the DTMS hydrolysate is not used to modify the silica, and the rest of the operation conditions and operation steps are the same as those of Example Six, to obtain a flexible photovoltaic cable.

[0063] Comparative Example Two

[0064] The difference between this comparative example and Example Six is that the GPS hydrolysate is not used to modify the silica, and the rest of the operation conditions and operation steps are the same as those of Example Six, to obtain a flexible photovoltaic cable.

[0065] Comparative Example Three

[0066] The difference between this comparative example and Example Six is that the modified silica is not added in the preparation process of the inner layer cable material and the outer layer cable material, and the rest of the operation conditions and operation steps are the same as those of Example Six, to obtain a flexible photovoltaic cable.

[0067] Comparative Example Four

[0068] The difference between the present comparative example and Example 6 is that the inner cable material is added into the hopper of the twin-screw extruder, the cable core made of pure copper material is drawn out through the wire drawing device and located at the center of the concentric die, and extruded under the condition that the extrusion temperature is 233°C and the rotation speed of the twin screw is 500 rpm, and cooled to room temperature to coat the base layer outside the cable core; the outer cable material is added into the hopper of the twin-screw extruder, the cable core coated with the base layer is drawn out through the wire drawing device and located at the center of the concentric die, and extruded under the condition that the extrusion temperature is 233°C and the rotation speed of the twin screw is 500 rpm, and cooled to room temperature to coat the protective layer outside the base layer, to obtain the flexible photovoltaic cable.

[0069] Standard heat and humidity aging test

[0070] Take 25 flexible photovoltaic cables prepared in each example and each comparative example, and divide them into 5 groups of samples on average, and place them in a constant temperature and humidity test chamber with a temperature of 85°C and a relative humidity of 85%, and at the 0th hour, the 500th hour, the 1000th hour, the 2000th hour and the 3000th hour, take out one group of samples from each example and each comparative example, and place them in a constant temperature and humidity test chamber with a temperature of 23°C and a relative humidity of 50% for 24 hours, and then test the tensile strength (according to the ASTM D638 standard) and the interlayer peeling strength (according to the IEC 60811-509 standard) of 5 flexible photovoltaic cables in the group of samples, take the average value, and perform the dynamic bending test on each flexible photovoltaic cable according to the EN 50618:2014 standard, and test the insulation resistance value of the photovoltaic cable that has been subjected to the dynamic bending test, and the results are shown in Tables 1 and 2.

[0071] Table 1

[0072]

[0073] Table 2

[0074]

[0075] It can be seen from Table 1 and Table 2 that compared with Example 5, the tensile strength, interlayer peeling strength and insulation performance of Examples 1 to 4 and Example 6 are slightly better than those of Example 5, which indicates that the addition of TMPTGE and EMI-24 in the outer cable material can improve the interfacial bonding force between the base layer and the protective layer and reduce the interfacial defects; compared with Comparative Example 1, Comparative Example 2 and Comparative Example 3, the flexible photovoltaic cable prepared by the application still has greater tensile strength and interlayer peeling strength after aging in a high-temperature and high-humidity environment for 3000h, and still has good insulation performance after the bending test, which indicates that the addition of modified silicon dioxide treated by GPS hydrolysate and DTMS hydrolysate in the preparation process of the inner cable material and the outer cable material can inhibit the cracking of the base layer when used in a high-temperature and high-humidity environment, and improve the service life of the flexible photovoltaic cable in a humid environment; compared with Comparative Example 4, the flexible photovoltaic cable prepared by the application still has greater tensile strength and interlayer peeling strength after aging in a high-temperature and high-humidity environment for 3000h, and still has good insulation performance, which indicates that the flexible photovoltaic cable prepared by the double-layer co-extrusion process can improve the interfacial bonding force between the base layer and the protective layer, reduce the interfacial defects, prevent water from contacting the base layer, inhibit the hydrolysis of polycaprolactam, and improve the service life of the flexible photovoltaic cable in a humid environment.

Claims

1. A method for the preparation of a flexible photovoltaic cable, characterized in that, It comprises the following steps: S1, mixing polycaprolactam, modified silica, PP-g-MAH and polypropylene to obtain inner cable material; S2, mixing modified silica, EVA-g-MAH, EVA, polyether TPU and polyvinylidene fluoride to obtain outer cable material; S3, feeding the inner cable material and the outer cable material into a double-layer co-extrusion machine, and extruding concentrically with the cable core under the conditions of an extrusion temperature of 230-235℃ and a double-screw rotation speed of 400-500rpm, and cooling to obtain a flexible photovoltaic cable; The modified silica is obtained by sequentially treating silica with GPS hydrolysate and DTMS hydrolysate.

2. A method of making a flexible photovoltaic cable according to claim 1, characterized in that, In the step S1, the modified silica, PP-g-MAH and lubricant are mixed, and then fed into an extruder for extrusion at an extrusion temperature of 160-170℃, and after cooling and granulation, a PP-based masterbatch is obtained, and then the PP-based masterbatch, polycaprolactam and polypropylene are mixed to obtain the inner cable material.

3. A method of making a flexible photovoltaic cable according to claim 2, wherein, In the step S2, the modified silica, EVA-g-MAH and lubricant are mixed, and then fed into an extruder for extrusion at an extrusion temperature of 180-190℃, and after cooling, granulation and drying, an EVA system functional masterbatch is obtained, and then the EVA system functional masterbatch, EVA, polyether TPU and polyvinylidene fluoride are mixed to obtain the outer cable material.

4. A method of making a flexible photovoltaic cable according to claim 3, wherein, The outer cable material further comprises TMPTGE and EMI-24.

5. The method for preparing a flexible photovoltaic cable according to claim 1, characterized in that, The modified silica is prepared by dispersing silica in anhydrous ethanol, adding GPS hydrolysate, stirring at 500-550rpm for 1.5-2.5h, dispersing in anhydrous ethanol after filtration and anhydrous ethanol washing, adding DTMS hydrolysate, stirring at 450-500rpm for 2-3h, and after filtration, tert-butyl alcohol solution washing and freeze-drying, the modified silica is obtained.

6. A method of making a flexible photovoltaic cable according to claim 5, wherein, The temperature of the freeze-drying is -40--30℃, the pressure is 10-20Pa, and the drying time is 24-28h.

7. The method for preparing a flexible photovoltaic cable according to claim 1, characterized in that, The GPS hydrolysate is prepared by mixing anhydrous ethanol, GPS and acetic acid solution, adding deionized water under continuous stirring, and stirring at 300-400rpm for 1.5-2.5h to obtain the GPS hydrolysate.

8. The method for preparing a flexible photovoltaic cable according to claim 1, characterized in that, The DTMS hydrolysate is prepared by mixing anhydrous ethanol, DTMS and acetic acid solution, slowly adding deionized water under continuous stirring, and stirring at 300-400rpm for 3-4h to obtain the DTMS hydrolysate.

9. A flexible photovoltaic cable, characterized by The flexible photovoltaic cable is prepared by the method of any one of claims 4-8, comprising a cable core, an inner cable material and an outer cable material, the inner cable material comprising the following raw materials in parts by mass: PP-based masterbatch 14-17 parts, polycaprolactam 155-165 parts, polypropylene 90-110 parts; the outer cable material comprising the following raw materials in parts by mass: EVA system functional masterbatch 10-14 parts, EVA 12-16 parts, polyether TPU 100-109 parts, polyvinylidene fluoride 80-90 parts, TMPTGE 0-5 parts, EMI-24 0-0.2 parts; the PP-based masterbatch comprising the following raw materials in parts by mass: modified silicon dioxide 18-22 parts, PP-g-MAH 72-80 parts, lubricant 0.3-0.4 parts; the EVA system functional masterbatch comprising the following raw materials in parts by mass: modified silicon dioxide 18-23 parts, EVA-g-MAH 68-75 parts, lubricant 0.3-0.4 parts; the lubricant is stearic acid; the material of the cable core is pure copper or tin-plated copper.

10. A flexible photovoltaic cable according to claim 9, characterised in that, The modified silicon dioxide comprises the following raw materials in parts by mass: silicon dioxide 45-55 parts, GPS hydrolysate 20-30 parts, DTMS hydrolysate 20-30 parts; the GPS hydrolysate comprises the following raw materials in parts by mass: anhydrous ethanol 190-210 parts, GPS 20-25 parts, 3-4wt% acetic acid solution 3-5 parts, deionized water 8-10 parts; the DTMS hydrolysate comprises the following raw materials in parts by mass: anhydrous ethanol 195-215 parts, DTMS 25-27 parts, 4-5wt% acetic acid solution 5-7 parts, deionized water 10-13 parts.

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