Composite conductive material, semi-conductive water-blocking buffer layer and application

Abstract

The invention discloses a composite conductive material which is prepared from the following raw materials: 50-60 parts of polypropylene, 20-30 parts of nylon, 15-30 parts of carbon black and 5-10 parts of a chain extender, the melt mass flow rate of the polypropylene is 300g / 10min-1000g / 10min, the measurement temperature of the melt mass flow rate of the polypropylene is 230 DEG C, and the nominal load is 2.16 kg. The composite conductive material has excellent deformation resistance, conductivity and radial water blocking performance, the prepared semi-conductive water blocking buffer layer is widely applied to cables / high-voltage cables, tightness and electrical connection between the semi-conductive water blocking buffer layer and other parts are greatly improved, potential difference discharge is reduced, the water blocking effect is achieved, and the service life of the semi-conductive water blocking buffer layer is prolonged. According to the utility model, the production of the ablation phenomenon is greatly reduced, the weight of the semi-conductive water-blocking buffer layer is also reduced, and the operation stability, reliability and safety of the cable are obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of high-voltage power cables, and in particular to a composite conductive material, a semiconductive water-repellent buffer layer and applications. Background Art

[0002] Cables are often laid in outdoor environments, including humid environments such as underground and underwater. In order to ensure the long-term operation stability of cables, water-blocking structures are essential protective measures that can effectively resist the intrusion of external moisture and ensure that cables can work stably and long-term in harsh environments. The commonly used water-blocking structure is a semi-conductive buffer water-blocking layer, which has a water-blocking powder filled with sodium polyacrylate as the base. Due to its three-dimensional mesh structure, it can absorb a hundred times its own weight of water, thereby achieving a water-blocking effect. At present, domestic high-voltage power cables are prone to breakdown failures caused by ablation of the semi-conductive water-blocking buffer layer under long-term operating conditions. The long-term accumulation of ablation on the semi-conductive water-blocking buffer layer will cause cable body failure, affecting the safe operation of the high-voltage power cable. Therefore, it is urgent to develop an efficient water-blocking material and structure. Summary of the invention

[0003] Based on this, it is necessary to provide a composite conductive material, a semiconductor water-resistant buffer layer and an application having excellent mechanical properties, electrical properties, radial water-resistant capability and reduced ablation.

[0004] In the first aspect, the present invention provides a composite conductive material. The raw material composition of the composite conductive material includes 50-60 parts of polypropylene, 20-30 parts of nylon, 15-30 parts of carbon black and 5-10 parts of chain extender, calculated by weight; the melt mass flow rate of the polypropylene is 300g / 10min-1000g / 10min, and the measurement temperature of the melt mass flow rate of the polypropylene is 230°C and the nominal load is 2.16kg.

[0005] In some embodiments, the composite conductive material satisfies at least one of the following (1) to (6):

[0006] (1) The nylon in the composite conductive material is selected from one or more of nylon 66, nylon 6, nylon 11 and nylon 1010;

[0007] (2) The particle size of the carbon black in the composite conductive material is 20nm-40nm;

[0008] (3) The resistivity of the carbon black in the composite conductive material is 0.2Ω / m-0.4Ω / m;

[0009] (4) The chain extender in the composite conductive material is selected from one or more of ethylene glycol, propylene glycol, butanediol and 2-methyl-1,3-propanediol;

[0010] (5) The composite conductive material further comprises 0.5 - 2 parts by mass of an antioxidant;

[0011] (6) The composite conductive material further comprises a hindered phenol antioxidant and / or a phosphite antioxidant.

[0012] In a second aspect, the present invention also provides a method for preparing a composite conductive material, the composite conductive material being the above-mentioned composite conductive material, and the preparation method comprising the following steps:

[0013] Mix the raw materials for preparing the composite conductive material to obtain a mixture, and melt-extrude the mixture.

[0014] In a third aspect, the present invention also provides a conductive film, the composite conductive film comprising the above-mentioned composite conductive material, or comprising the composite conductive material prepared by the above-mentioned preparation method.

[0015] In a fourth aspect, the present invention also provides a semiconductive water-resistant buffer layer, the water-resistant buffer layer satisfying the following condition (1) or (2):

[0016] (1) The water-resistant buffer layer comprises the above-mentioned conductive film;

[0017] (2) The water-resistant buffer layer comprises the above-mentioned conductive film, and the thickness of the conductive film is 0.1 - 0.15 mm.

[0018] In some embodiments, the water-resistant buffer layer further comprises a non-woven fabric, and the non-woven fabric is laminated with the conductive film.

[0019] In some embodiments, the raw materials for preparing the non-woven fabric include polypropylene and carbon black;

[0020] Optionally, the non-woven fabric further satisfies at least one of the following (1) - (6):

[0021] (1) The melt mass flow rate of the polypropylene is 300 g / 10 min - 1000 g / 10 min, and the measurement temperature of the melt mass flow rate of the polypropylene is 230 °C and the nominal load is 2.16 kg;

[0022] (2) The carbon black is selected from conductive carbon black and / or acetylene black;

[0023] (3) The average particle size of the carbon black is 20 nm - 40 nm;

[0024] (4) The resistivity of the carbon black is 0.05 Ω / m - 0.2 Ω / m;

[0025] (5) The polypropylene is 80 - 90 parts by mass, and the carbon black is 20 - 25 parts by mass;

[0026] (6) The non - woven fabric has a thickness of 0.8 mm - 1.2 mm.

[0027] In some embodiments, the number of the conductive films in the conductive water - resistant buffer layer is at least two, and the non - woven fabric is located between two adjacent conductive films.

[0028] Fifthly, the present invention also provides a cable, and the cable includes the above - mentioned semiconductive water - resistant buffer layer.

[0029] In some embodiments, the operating voltage of the cable is at a voltage level of 110 kV or above.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The existing semiconductive water - resistant buffer layer is usually a three - layer structure of a fluffy cotton layer, a water - resistant powder layer, and a non - woven fabric layer. The semiconductive water - resistant buffer layer with such materials and structure has poor strength, heat resistance, water - resistance, and electrical properties. During the long - term power transmission of the cable, due to factors such as heat generated by high voltage or the environment, the semiconductive water - resistant buffer layer in this kind of cable is extremely likely to deform, resulting in phenomena such as gaps and poor contact between the semiconductive water - resistant buffer layer and the metal protective sleeve, insulating sleeve, etc., thus generating a floating potential and causing serious problems such as discharge and ablation, affecting the normal operation of the cable. However, the present invention uses polypropylene and nylon within a specific melt index range as the matrix materials, enabling the composite conductive material to have characteristics such as high strength, heat resistance, and wear resistance, and excellent anti - deformation ability, reducing the serious ablation problem caused by the deformation of the semiconductive water - resistant buffer layer. At the same time, the cross - linking density of polypropylene and nylon is further increased through a chain extender, further enhancing the anti - deformation ability of the matrix material and improving the radial water - resistant performance, reducing the ablation phenomenon; furthermore, after further compounding with carbon black, the electrical conductivity and strength of the material are enhanced, especially reducing the potential difference generated when there are gaps and poor contact in the semiconductive water - resistant buffer layer, ensuring good electrical connection and reducing the generation of ablation phenomena.

[0032] The composite conductive material of the present invention has excellent mechanical properties, electrical properties, and radial water - resistant performance, can be widely used as a semiconductive water - resistant buffer layer material in cables / high - voltage cables, reducing the ablation failure of the cable, and has significant progress compared with the prior art. The composite conductive material of the present invention also greatly reduces the mass of the semiconductive water - resistant buffer layer, significantly improving the operation stability, reliability, and safety of the cable. Description of the Drawings

[0033] Figure 1This is a schematic diagram of the structure of the semiconducting water-repellent buffer layer of the present invention, in which A and B are conductive films and C is a non-woven fabric. DETAILED DESCRIPTION

[0034] For ease of understanding of the present invention, preferred embodiments of the present invention are provided below to more fully describe the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0035] It should be noted that the experimental methods in the following examples of the present invention without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0037] Ablation: The phenomenon in which the surface material of an object moving at an extremely high speed melts, disappears and deforms under the action of hot gases.

[0038] Cable ablation: refers to the phenomenon that the insulation layer, conductor and other parts of the cable are damaged, melted or even burned due to various reasons during the use of the cable due to the effects of high temperature, current and other factors.

[0039] Since high-voltage power cables are prone to breakdown failures caused by buffer layer ablation under long-term operating conditions, especially ablation on the semiconductor resistive water buffer layer, long-term accumulation may lead to cable body failure and affect the safe operation of the high-voltage power cable. Therefore, the present invention provides a composite conductive material that can be used for the semiconductor resistive water buffer layer of a high-voltage cable.

[0040] In the first aspect, the present invention provides a composite conductive material. The raw material composition of the composite conductive material includes 50-60 parts of polypropylene, 20-30 parts of nylon, 15-30 parts of carbon black and 5-10 parts of chain extender, calculated by weight; the melt mass flow rate of the polypropylene is 300g / 10min-1000g / 10min, and the melt mass flow rate is measured according to GB / T3682, and the measurement temperature of the melt mass flow rate is 230°C and the nominal load is 2.16kg.

[0041] In the composite conductive material of the present invention, polypropylene and nylon with a specific melt index are used as the matrix materials, which have good radial water-blocking performance. Further, by adding a chain extender, the crosslinking density of the two is increased, further improving this performance, and the carbon black material can be evenly dispersed, enhancing the conductive performance and reducing the ablation phenomenon caused by the potential difference during the operation of the cable. At the same time, the composite conductive material prepared from polypropylene and nylon with a specific melt index as the matrix materials of the present invention has excellent properties of high strength, heat resistance, wear resistance and radial water-blocking, and also has good conductive performance. By using a chain extender, the crosslinking density of polypropylene and nylon is further increased, greatly improving the above various properties of the matrix materials, especially significantly improving the mechanical properties. After further compounding with carbon black, the conductive performance and strength of the material are enhanced. Therefore, the composite conductive material of the present invention has excellent mechanical properties, electrical conductivity and radial water-blocking performance, and can reduce the ablation failure caused by the local increase in the resistivity in the cable due to poor contact.

[0042] In some embodiments, the type of the polypropylene is selected from one or more of T36, T38 and S38. It should be noted that all the sub-types under the polypropylene T36, T38 and S38 types are applicable to the present invention.

[0043] In some embodiments, the nylon in the composite conductive material is selected from one or more of nylon 66, nylon 6, nylon 11 and nylon 1010; further, by selecting nylon 66 in the composite conductive material of the present invention, higher strength, higher heat resistance and better wear resistance can be obtained, so that the composite conductive material can better maintain good electrical performance at higher temperatures, humidities and frequencies, and reduce the generation of potential difference.

[0044] Furthermore, the nylon 66 selected in the present invention is in the form of chips or pellets, and better effects can be achieved.

[0045] In some embodiments, the carbon black in the composite conductive material is conductive carbon black.

[0046] In some embodiments, the purity of the carbon black in the composite conductive material is 99%-99.5%.

[0047] In some embodiments, the particle size of the carbon black in the composite conductive material is 20nm-40nm, which can be better dispersed in the matrix material, enhancing the mechanical properties and conductive performance of the composite conductive material.

[0048] In some embodiments, the resistivity of the carbon black in the composite conductive material is 0.2Ω / m-0.4Ω / m, which can better enhance the conductive performance of the composite conductive material.

[0049] In some embodiments, the chain extender in the composite conductive material is selected from one or more of ethylene glycol, propylene glycol, butylene glycol, and 2-methyl-1,3-propanediol.

[0050] Optionally, the propylene glycol includes 1,2-propylene glycol and / or 1,3-propylene glycol.

[0051] Optionally, the butylene glycol includes one or more of 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol.

[0052] In some embodiments, an antioxidant is further added to the composite conductive material of the present invention, which can prevent the conductive film from oxidative degradation and ensure its service life and stability.

[0053] Optionally, the addition amount of the antioxidant is 0.5-2 parts by mass.

[0054] Optionally, the composite conductive material further comprises a hindered phenol antioxidant and / or a phosphite antioxidant.

[0055] Optionally, the antioxidant includes, but is not limited to, one or more selected from antioxidant 1010, antioxidant 1076, and antioxidant 168.

[0056] In a second aspect, the present invention also provides a method for preparing a composite conductive material, the composite conductive material being the composite conductive material described above, and the preparation method comprising the following steps:

[0057] Mix the raw materials for preparing the composite conductive material to obtain a mixed material, and melt-extrude the mixed material.

[0058] Optionally, mix polypropylene and a chain extender, or mix polypropylene, a chain extender, and an antioxidant;

[0059] Then add nylon and carbon black and mix evenly to obtain a mixed material, melt-blend the mixed material, and then extrude, cool, and pelletize to obtain the composite conductive material.

[0060] In some embodiments, the stirring speed during mixing in the preparation process is 400 r / min - 650 r / min, including but not limited to 400, 405, 410, 415, 420, 425, 430, 435, 440, 445, 450, 455, 460, 465, 470, 475, 480, 485, 490, 495, 500, 505, 510, 515, 520, 525, 530, 535, 540, 545, 550, 555, 560, 565, 570, 575, 580, 585, 590, 595, 600, 605, 610, 615, 620, 625, 630, 635, 640, 645, 650 r / min or any rotational speed within the rotational speed range formed by any two of the foregoing;

[0061] In some embodiments, the stirring speed for mixing polypropylene and a chain extender, or the stirring speed for mixing polypropylene, a chain extender, and an antioxidant, is 400 min - 500 min.

[0062] In some embodiments, the stirring speed for uniformly mixing nylon and carbon black is 550 min - 650 min.

[0063] In some embodiments, the temperature during mixing in the preparation process is 90°C - 120°C, including but not limited to 90, 95, 100°C, 105°C, 110°C, 115°C, 120°C or any temperature within the temperature range formed by any two of the foregoing;

[0064] In some embodiments, the temperature for mixing polypropylene and a chain extender, or the temperature for mixing polypropylene, a chain extender, and an antioxidant, is 90°C - 100°C.

[0065] In some embodiments, the temperature for uniformly mixing nylon and carbon black is 110°C - 120°C.

[0066] In some embodiments, the mixing time during the preparation process is 40 min - 2 h, including but not limited to 40 min, 45 min, 50 min, 55 min, 60 min, 1.2 h, 1.5 h, 1.8 h, 2 h or any time within the time range formed by any two of the foregoing.

[0067] In some embodiments, the time for mixing polypropylene and a chain extender, or the time for mixing polypropylene, a chain extender, and an antioxidant, is 40 min - 50 min.

[0068] In some embodiments, the time for uniformly mixing nylon and carbon black is 1.5 h - 2 h.

[0069] In some embodiments, the melt extrusion device is selected from twin-screw extruders.

[0070] In some embodiments, the melt extrusion step includes a feeding section at 110°C - 120°C, a melting section at 275°C - 285°C, a homogenization section at 270°C - 275°C, and a die head temperature of 270°C - 280°C;

[0071] Optionally, the temperature of the feeding section in the melt extrusion step includes but is not limited to 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120°C, or a temperature range formed by any two of the foregoing and any temperature within the range.

[0072] Optionally, the temperature of the melt extrusion includes but is not limited to 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285°C, or a temperature range formed by any two of the foregoing and any temperature within the range.

[0073] Optionally, the temperature of the homogenization section in the melt extrusion step includes but is not limited to 270, 270.5, 271, 271.5, 272, 272.5, 273, 273.5, 274, 274.5, 275°C, or a temperature range formed by any two of the foregoing and any temperature within the range.

[0074] Optionally, the die head temperature in the melt extrusion step includes but is not limited to 270, 270.5, 271, 271.5, 272, 272.5, 273, 273.5, 274, 274.5, 275, 275.5, 276, 276.5, 277, 277.5, 278, 278.5, 279, 279.5, 280°C, or a temperature range formed by any two of the foregoing and any temperature within the range.

[0075] In some embodiments, the preparation method of the composite conductive material further includes a post-treatment step for the composite conductive material: drying the obtained composite conductive material to remove moisture and volatile substances.

[0076] In a third aspect, the present invention also provides an application of a composite conductive material in a semiconductor resistive water buffer layer, where the composite conductive material includes the above-mentioned composite conductive material, or a composite conductive material prepared by the above-mentioned preparation method.

[0077] When the composite conductive material of the present invention is applied in a semiconductor resistive water buffer layer, the probability of ablation failure of the semiconductor resistive water buffer layer can be significantly reduced.

[0078] Fourth aspect, the present invention further provides a conductive film, and the composite conductive film includes the above-mentioned composite conductive material, or includes the composite conductive material prepared by the above-mentioned preparation method.

[0079] In some embodiments, the preparation method of the conductive film includes:

[0080] Melting and rolling the composite conductive material or the composite conductive material after post-treatment to obtain.

[0081] In some embodiments, the rolling temperature is set to 270°C - 285°C, including but not limited to 270, 270.5, 271, 271.5, 272, 272.5, 273, 273.5, 274, 274.5, 275, 275.5, 276, 276.5, 277, 277.5, 278, 278.5, 279, 279.5, 280, 281, 281.5, 282, 282.5, 283, 283.5, 284, 284.5, 285°C or any temperature within the temperature range formed by any two of the foregoing.

[0082] In some embodiments, the rolling pressure is 0.5 MPa - 1.5 MPa, including but not limited to 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 MPa or any pressure within the pressure range formed by any two of the foregoing.

[0083] In some embodiments, the rolling speed of the rolling is 0.5 m / min - 2 m / min, including but not limited to 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 m / min or any speed within the speed range formed by any two of the foregoing.

[0084] In some embodiments, the thickness of the rolled conductive film is 0.1 mm - 0.15 mm, including but not limited to 0.1, 0.105, 0.11, 0.115, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15 mm or any thickness within the thickness range formed by any two of the foregoing.

[0085] The conductive film provided by the present invention can be applied in a semiconductor resistive water buffer layer, which can reduce the probability of ablation failure of the semiconductor resistive water buffer layer; further, when the thickness of the provided conductive film is within the range of 0.1 mm - 0.15 mm, the above effect can be better achieved.

[0086] In some embodiments, the method for preparing the conductive thin film further includes processes such as cooling, drawing, and winding after melt rolling.

[0087] Fifthly, the present invention also provides a semiconductor water-resistant buffer layer, which has excellent electrical properties and radial water resistance, and has an extremely low probability of ablation failure.

[0088] In some embodiments, the conductive water-resistant buffer layer includes at least one of the above-mentioned conductive thin films.

[0089] In some embodiments, the conductive water-resistant buffer layer includes at least one of the above-mentioned conductive thin films, and the thickness of the conductive thin film is 0.1 mm - 0.15 mm. The conductive thin film within this thickness range can further reduce the probability of ablation failure of the semiconductor water-resistant buffer layer.

[0090] In some embodiments, the conductive water-resistant buffer layer further includes non-woven fabric, and the non-woven fabric is laminated with the conductive thin film.

[0091] The raw materials for preparing the non-woven fabric include polypropylene and carbon black;

[0092] Optionally, the polypropylene is selected from one or more of the models Z30S, Y1600, Y2600, and S700.

[0093] In some embodiments, polypropylene is used as the main material for melt-blown non-woven fabric. The polypropylene is selected from polypropylene with a melt mass flow rate (MFR) of 100 g / 10 min - 1000 g / 10 min. The melt mass flow rate of the polypropylene is measured according to GB / T3682, and the measurement temperature of the melt mass flow rate is 230 °C and the nominal load is 2.16 kg.

[0094] Using polypropylene within this melt mass flow rate range can make the melt more easily pass through the nozzle or die to form fine fibers;

[0095] In some embodiments, the carbon black is selected from conductive carbon black and / or acetylene black. Using this carbon black material enhances the conductive performance and strength of the non-woven fabric, meets the semi-conductive properties of the buffer layer, and improves the electrical reliability of the cable.

[0096] In some embodiments, the average particle size of the carbon black is 20 nm - 40 nm. The carbon black with this particle size can be better dispersed in polypropylene, improving the mechanical properties and conductivity of polypropylene or non-woven fabric.

[0097] In some embodiments, the resistivity of the carbon black is 0.05 Ω / m - 0.2 Ω / m, including but not limited to 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15 Ω / m or the resistivity ranges formed by any two of the foregoing and any resistivity within the range. Using carbon black with this resistivity can better improve the conductivity of the non-woven fabric.

[0098] In some embodiments, the polypropylene is 80 - 90 parts by mass, and the carbon black is 20 - 25 parts by mass; by mass fraction, the feeding ratio of polypropylene and carbon black includes but not limited to 80:20, 85:20, 90:20, 80:25, 85:25, 90:25, 82:20, 82:25, 80:22, 85:22, 90:22 or the ratio ranges formed by any two of the foregoing and any ratio within the range.

[0099] The method for preparing the non-woven fabric includes:

[0100] Mix the raw materials for preparing the non-woven fabric to obtain a mixture, melt-extrude the mixture, and then perform melt blowing and hot pressing to prepare the non-woven fabric.

[0101] In some embodiments, the stirring speed of the mixing is 500 r / min - 600 r / min, including but not limited to 500, 505, 510, 515, 520, 525, 530, 535, 540, 545, 550, 555, 560, 565, 570, 575, 580, 585, 590, 595, 600 r / min or the speed ranges formed by any two of the foregoing and any speed within the range.

[0102] In some embodiments, the stirring temperature of the mixing is 90°C - 100°C, including but not limited to 90, 90.5, 91, 91.5, 92, 92.5, 93, 93.5, 94, 94.5, 95, 95.5, 96, 96.5, 97, 97.5, 98, 98.5, 99, 99.5, 100°C or the temperature ranges formed by any two of the foregoing and any temperature within the range.

[0103] In some embodiments, the equipment for melt blending is selected from a twin-screw extruder.

[0104] In some embodiments, the melt extrusion temperature includes: the feeding section is 110 - 120°C, the melting section is 215 - 225°C, the homogenization section is 210 - 215°C, and the die head temperature is 215 - 220°C;

[0105] Optionally, the temperature of the feeding section in the melt extrusion step includes but is not limited to 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120 °C, or the temperature range formed by any two of the foregoing and any temperature within the range.

[0106] Optionally, the melting temperature in the melt extrusion step includes but is not limited to 215, 215.5, 216, 216.5, 217, 217.5, 218, 218.5, 219, 219.5, 220, 220.5, 221, 221.5, 222, 222.5, 223, 223.5, 224, 224.5, 225 °C, or the temperature range formed by any two of the foregoing and any temperature within the range.

[0107] Optionally, the temperature of the homogenization section in the melt extrusion step includes but is not limited to 210, 210.5, 211, 211.5, 212, 212.5, 213, 213.5, 214, 214.5, 215 °C, or the temperature range formed by any two of the foregoing and any temperature within the range.

[0108] Optionally, the die temperature in the melt extrusion step includes but is not limited to 215, 215.5, 216, 216.5, 217, 217.5, 218, 218.5, 219, 219.5, 220 °C, or the temperature range formed by any two of the foregoing and any temperature within the range.

[0109] In some embodiments, in order to remove moisture in the material and avoid generating bubbles or affecting the fiber drawing effect during the meltblowing process, during the preparation process of the non-woven fabric, drying can also be performed after the melt extrusion step;

[0110] The temperature of the drying is 70 °C - 90 °C, including but not limited to 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 °C, or the temperature range formed by any two of the foregoing and any temperature within the range;

[0111] The time of the drying is 0.5 h - 5 h, including but not limited to 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5 h, or the time range formed by any two of the foregoing and any time within the range.

[0112] In some embodiments, during the preparation process of the non-woven fabric, an extrusion step is also performed before meltblowing;

[0113] The extrusion step is achieved by a screw extruder. In the screw extruder, the material forms a uniform melt. Before entering the meltblown die head, the melt needs to pass through a fine filter to remove possible impurities and unmolten particles, ensuring the purity and quality of the fibers. The melt is ejected at high speed from the spinneret holes of the meltblown die head and is simultaneously strongly stretched by hot air to form ultrafine fibers. By adjusting the speed, temperature, and direction of the hot air, the diameter, orientation, and distribution of the fibers can be controlled. The ultrafine fibers are intertwined with each other in the air to form a network structure and are quickly cooled and solidified under the mixing action of hot air and the surrounding cold air to form a non-woven base fabric with a certain thickness and strength. The non-woven base fabric is sent into a hot rolling machine for hot pressing treatment to form a semi-conductive non-woven fabric with a certain mechanical strength and buffering performance;

[0114] The non-woven fabric prepared by meltblowing in the present invention has good mechanical strength, strong compression resistance and deformation resistance when stressed, can meet the buffering performance requirements of the semi-conductive water-resistant buffer layer, and thus reduce or avoid the contact failure caused by deformation of the semi-conductive water-resistant buffer layer and the generation of floating potential, and reduce the ablation phenomenon caused by discharge due to the potential difference between the two. Especially when the non-woven fabric is placed between two adjacent conductive films, it can better enable the semi-conductive water-resistant buffer layer to achieve the above effects.

[0115] In some embodiments, the meltblowing is a stepped temperature treatment in the temperature range of 180°C - 220°C, including but not limited to the temperature ranges formed by any two of 180, 185, 190, 195, 200, 205, 210, 215, 220°C.

[0116] In some embodiments, the temperature during die head spinning of the meltblowing is 220°C - 230°C, including but not limited to 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230°C or the temperature ranges formed by any two of the foregoing and any temperature within the range.

[0117] In some embodiments, the thickness of the non-woven fabric is 0.8 mm - 1.2 mm, including but not limited to 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.1, 0.11, 0.115, 0.12 mm or the thickness ranges formed by any two of the foregoing and any thickness within the range. Within this thickness range, the probability of ablation failure of the semi-conductive water-resistant buffer layer can be further reduced.

[0118] In some embodiments, the semi-conductive water-resistant buffer layer comprises at least two layers of electric films, and the non-woven fabric is located between two adjacent conductive films.

[0119] The structure enclosed by the conductive thin film and the non-woven fabric layer plays a good role in radially blocking moisture, preventing moisture from continuing to penetrate along the radial direction of the cable, and thus reducing the occurrence of cable ablation.

[0120] In some embodiments, at least two layers of electric thin films and non-woven fabrics are fed into a hot rolling mill for hot pressing treatment. The non-woven fabric is located between two adjacent conductive thin films, and a semi-conductive moisture-resistant buffer layer is obtained by hot pressing. As shown in the Figure 1 drawing, A and B in the drawing are conductive thin film layers, and C is a non-woven fabric layer.

[0121] In some embodiments, the temperature of the hot pressing treatment is 215°C - 225°C, including but not limited to 215, 215.5, 216, 216.5, 217, 217.5, 218, 218.5, 219, 219.5, 220, 220.5, 221, 221.5, 222, 222.5, 223, 223.5, 224, 224.5, 225°C or any temperature within the temperature range formed by any two of the foregoing.

[0122] In some embodiments, the pressure of the hot pressing treatment is 30 bar - 40 bar, including but not limited to 30, 30.5, 31, 31.5, 32, 32.5, 33, 33.5, 34, 34.5, 35, 35.5, 36, 36.5, 37, 37.5, 38, 38.5, 39, 39.5, 40 bar or any pressure within the pressure range formed by any two of the foregoing.

[0123] In some embodiments, the thickness of the semi-conductive moisture-resistant buffer layer is 1.0 mm - 1.5 mm, including but not limited to 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5 mm or any thickness within the thickness range formed by any two of the foregoing.

[0124] The semi-conductive moisture-resistant buffer layer of the present invention has the performance of resisting material deformation, ensuring a tight connection between the protective sheath and the insulation shielding layer, reducing the discharge caused by potential difference. At the same time, due to the tight connection between the protective sheath and the insulation shielding layer, it has a strong moisture barrier effect, preventing moisture from continuing to penetrate along the radial direction of the cable, thereby reducing the occurrence of ablation.

[0125] In a sixth aspect, the present invention further provides a cable, and the cable includes the above-mentioned semi-conductive moisture-resistant buffer layer.

[0126] In some embodiments, the operating voltage of the cable is a voltage level of 110 kV or above.

[0127] For the experimental parameters not specified in the following specific embodiments, priority shall be given to the guidance provided in this application document. It is also possible to refer to experimental manuals in the art or other experimental methods known in the art, or to the experimental conditions recommended by the manufacturer.

[0128] The raw materials and reagents involved in the following specific embodiments can be obtained commercially or can be prepared by those skilled in the art according to known means.

[0129] In some embodiments, the polypropylene T36, polypropylene T38, and polypropylene S38, as well as all the sub - models under the polypropylene model numbers, are respectively purchased from Dongguan Liancheng Plastic Co., Ltd., Beijing Xinsu Century Trading Co., Ltd., and Dongguan Chenfeng Plastic Raw Materials Co., Ltd.

[0130] Example 1: Preparation of Composite Conductive Material

[0131] By mass fraction, the raw materials for preparing the composite conductive material in this example include:

[0132] 50 parts of polypropylene T38,

[0133] 30 parts of nylon 66,

[0134] 20 parts of carbon black,

[0135] 2 parts of ethylene glycol,

[0136] 4 parts of 1,2 - propanediol,

[0137] 0.25 part of antioxidant 1010, and

[0138] 0.25 part of antioxidant 1076.

[0139] The nylon 66 is in pellet form;

[0140] The carbon black is conductive carbon black with a purity of 99%, an average particle size of 20 nm - 40 nm, and a resistivity of 0.3 Ω / m.

[0141] The preparation method of the composite conductive material in this example includes the following steps:

[0142] According to the above raw material feeding amounts, polypropylene T38, ethylene glycol, propylene glycol, antioxidant 1010 and antioxidant 1076 are mixed and stirred. During the mixing and stirring process, the rotation speed of the mixer is set to 400 r / min, the stirring temperature is 90 °C, and the stirring time is 40 min. Then nylon 66 and carbon black are added and mixed evenly. During the mixing process, the rotation speed of the mixer is set to 550 r / min, the stirring temperature is 110 °C, and the stirring time is 1.5 h to obtain a mixed material. The mixed material is conveyed to a twin-screw extruder for melt blending and then extruded. The extrusion temperature of the twin-screw extruder is: the feeding section is 110 °C, the melting section is 275 °C, the homogenization section is 270 °C, and the die head temperature is 275 °C. Then it is cooled and pelletized to obtain a composite conductive material, denoted as A1;

[0143] The prepared composite conductive material A1 is sent into a dryer for drying treatment to remove moisture and volatile substances.

[0144] Example 2. Preparation of composite conductive material

[0145] By mass, the raw materials for preparing the composite conductive material in this example include:

[0146] 50 parts of polypropylene S38,

[0147] 30 parts of nylon 66,

[0148] 20 parts of carbon black,

[0149] 5 parts of 1,3-propanediol,

[0150] 5 parts of 1,3-butanediol, and

[0151] 0.5 part of antioxidant 1010.

[0152] The nylon 66 is in pellet form;

[0153] The carbon black is conductive carbon black with a purity of 99%, an average particle size of 20 nm - 40 nm, and a resistivity of 0.2 Ω / m.

[0154] The preparation method of the composite conductive material in this example includes the following steps:

[0155] According to the above raw material feeding amounts, polypropylene S38, propylene glycol, 1,3-butanediol, and antioxidant 1010 are mixed and stirred. During the mixing and stirring process, the rotation speed of the mixer is set to 500 r / min, the stirring temperature is 100 °C, and the stirring time is 50 min. Then nylon 66 and carbon black are added and mixed evenly. During the mixing process, the rotation speed of the mixer is set to 600 r / min, the stirring temperature is 110 °C, and the stirring time is 2 h to obtain a mixed material. The mixed material is conveyed to a twin-screw extruder for melt blending and then extruded. The extrusion temperature of the twin-screw extruder is: the feeding section is 110 °C, the melting section is 280 °C, the homogenizing section is 270 °C, and the die head temperature is 280 °C. Then it is cooled and pelletized to obtain a composite conductive material, denoted as A2;

[0156] The prepared composite conductive material A2 is sent into a dryer for drying treatment to remove moisture and volatile substances.

[0157] Example 3. Preparation of Composite Conductive Material

[0158] By mass, the raw materials for preparing the composite conductive material in this example include:

[0159] 50 parts of polypropylene T36,

[0160] 30 parts of nylon 66,

[0161] 20 parts of carbon black,

[0162] 7 parts of 1,3-butanediol,

[0163] 3 parts of 2-methyl-1,3-propanediol, and

[0164] 0.4 parts of antioxidant 1010, and.

[0165] 0.6 parts of antioxidant 168.

[0166] The nylon 66 is in the form of slices;

[0167] The carbon black is conductive carbon black with a purity of 99%, an average particle size of 20 nm - 40 nm, and a resistivity of 0.2 Ω / m.

[0168] The preparation method of the composite conductive material in this example includes the following steps:

[0169] According to the above raw material feeding amounts, polypropylene T36, ethylene glycol, propylene glycol, antioxidant 1010 and antioxidant 1076 are mixed and stirred. During the mixing and stirring process, the rotation speed of the mixer is set to 500 r / min, the stirring temperature is 90 °C, and the stirring time is 50 min. Then nylon 66 and carbon black are added and mixed evenly. During the mixing process, the rotation speed of the mixer is set to 600 r / min, the stirring temperature is 100 °C, and the stirring time is 2 h to obtain a mixed material. The mixed material is transported to a twin-screw extruder for melt blending and then extruded. The extrusion temperature of the twin-screw extruder is: the feeding section is 110 °C, the melting section is 275 °C, the homogenization section is 270 °C, and the die head temperature is 280 °C. Then it is cooled and pelletized to obtain a composite conductive material, denoted as A3;

[0170] The prepared composite conductive material A3 is sent into a dryer for drying treatment to remove moisture and volatile substances.

[0171] Example 4. Preparation of Composite Conductive Material

[0172] The composite conductive material A4 prepared in this example is basically the same as that in Example 1, except that the chain extender component is different. In this example, an equal amount of dicumyl peroxide is used to replace the chain extender, and the other components and preparation methods are the same as those in Example 1.

[0173] Example 5. Preparation of Composite Conductive Material

[0174] The composite conductive material A5 prepared in this example is basically the same as that in Example 1, except that the nylon model is different. In this example, an equal amount of nylon 610 is used to replace nylon 66, and the other components and preparation methods are the same as those in Example 1.

[0175] Example 6. Preparation of Conductive Film

[0176] The dried composite conductive materials A1 - A5 in Examples 1 - 5 are used to prepare conductive films. The preparation steps include:

[0177] The dried composite conductive material A1 is fed into the hopper of a calender, melted and calendered into a film with a certain thickness in the calender. The temperature of the calender is set to 270 °C, the pressure is 0.5 - 1.5 MPa, and the calendering speed is 0.5 - 2 m / min. The calendered film goes through processes such as cooling, traction, and winding to obtain a conductive film B1, and the thickness of the conductive film is 0.1 mm.

[0178] Feed the dried composite conductive material A2 into the hopper of a calender, melt and calender it into a film with a certain thickness in the calender. The temperature of the calender is set at 270 °C, the pressure is 0.5 - 1.5 MPa, and the calendering speed is 0.5 - 2 m / min. The calendered film is processed through procedures such as cooling, traction, and winding to obtain the conductive film B2, and the thickness of the conductive film is 0.1 mm.

[0179] Feed the dried composite conductive material A3 into the hopper of a calender, melt and calender it into a film with a certain thickness in the calender. The temperature of the calender is set at 270 °C, the pressure is 0.5 - 1.5 MPa, and the calendering speed is 0.5 - 2 m / min. The calendered film is processed through procedures such as cooling, traction, and winding to obtain the conductive film B3, and the thickness of the conductive film is 0.15 mm.

[0180] Feed the dried composite conductive material A4 into the hopper of a calender, melt and calender it into a film with a certain thickness in the calender. The temperature of the calender is set at 270 °C, the pressure is 0.5 - 1.5 MPa, and the calendering speed is 0.5 - 2 m / min. The calendered film is processed through procedures such as cooling, traction, and winding to obtain the conductive film B4, and the thickness of the conductive film is 0.1 mm.

[0181] Feed the dried composite conductive material A5 into the hopper of a calender, melt and calender it into a film with a certain thickness in the calender. The temperature of the calender is set at 270 °C, the pressure is 0.5 - 1.5 MPa, and the calendering speed is 0.5 - 2 m / min. The calendered film is processed through procedures such as cooling, traction, and winding to obtain the conductive film B5, and the thickness of the conductive film is 0.1 mm.

[0182] Example 7. Preparation of a Semiconductor Resistive Water Buffer Layer

[0183] The semiconductor resistive water buffer layer prepared in this example includes a three-layer structure of a conductive film, a non-woven fabric, and a conductive film arranged in sequence, specifically including: two adjacent conductive films, and a non-woven fabric located between the two adjacent conductive films.

[0184] The preparation method of the non-woven fabric is as follows:

[0185] By mass fraction, the raw material feeding of the non-woven fabric is: 80 parts of polypropylene S700 and 20 parts of carbon black;

[0186] The polypropylene is polypropylene S700 produced by Yangzi Petrochemical. The purity of the conductive carbon black used is 99.5%, the average particle size of the carbon black is 20 nm - 40 nm, and the resistivity of the carbon black is 0.1 Ω / m.

[0187] Mix the above 80 parts of polypropylene S700 and 20 parts of carbon black using a blender. Set the rotational speed of the blender to 500 r / min, the stirring temperature to 90 °C, and the stirring time to 1 h. After mixing evenly, convey the prepared mixed material to a twin-screw extruder for melt blending, and extrude it through the die head of the extruder. The extrusion temperature of the twin-screw extruder is as follows: the feeding section is 110 °C, the melting section is 215 °C, the homogenization section is 210 °C, and the die head temperature is 215 °C. After cooling and pelletizing, obtain the masterbatch. Dry the masterbatch at 80 °C for 2 hours to remove the moisture in the masterbatch, and then add it to a screw extruder to form a uniform melt, and then carry out extrusion. Set the temperature of the feeding section of the screw extruder to 180 °C, the temperature of the mixing section to 220 °C, and the temperature of the extrusion section to 230 °C. Then carry out meltblowing to prepare a non-woven base fabric. The temperature during die head spinning in the meltblowing process is 220 °C. Finally, send the non-woven base fabric into a hot rolling machine for hot pressing treatment to prepare non-woven fabric C1. The thickness of the non-woven fabric is 0.8 mm.

[0188] It should be noted that the melt needs to pass through a fine filter before entering the meltblowing die head to remove possible impurities and unmolten particles, ensuring the purity and quality of the fibers. The melt is ejected at high speed from the spinneret holes of the meltblowing die head and is simultaneously strongly drawn by hot air to form ultrafine fibers. By adjusting the speed, temperature, and direction of the hot air, the diameter, orientation, and distribution of the fibers can be controlled. The ultrafine fibers are intertwined with each other in the air to form a network structure and are quickly cooled and solidified under the mixing action of hot air and the surrounding cold air to form a non-woven base fabric with a certain thickness and strength.

[0189] The preparation process of the semiconductor resistive water buffer layer in this embodiment includes:

[0190] Place non-woven fabric C1 between adjacent conductive films B1 and B1, and then send it into a hot rolling machine for hot pressing treatment to prepare a three-layer structured semiconductor resistive water buffer layer, denoted as P1. The hot pressing temperature of the hot rolling machine is 215 °C, and the hot pressing pressure is 30 bar. The thickness of the three-layer structured semiconductor resistive water buffer layer prepared in this embodiment is 1 mm.

[0191] It should be noted that the two conductive films in the above-prepared three-layer structured semiconductor resistive water buffer layer can be the same or different. For example, the conductive film can be any one of the conductive films B1~B3 prepared in Example 6, and the above effects can be achieved.

[0192] This embodiment also prepared a semiconductor resistive water buffer layer P2: Place non-woven fabric C1 between adjacent conductive films B1 and B4;

[0193] In addition, a semiconductor resistive water buffer layer P3 was prepared: Place non-woven fabric C1 between adjacent conductive films B1 and B5.

[0194] Example 8: Preparation of Semiconductor Resistive Water Buffer Layer

[0195] The semiconductor resistive water buffer layer prepared in this example has a three-layer structure, including two adjacent conductive films and a non-woven fabric located between the two adjacent conductive films.

[0196] The preparation method of the non-woven fabric is as follows:

[0197] By mass fraction, the raw material feeding of the non-woven fabric is: 90 parts of polypropylene S700 and 25 parts of carbon black;

[0198] The polypropylene is polypropylene Y2600 produced by Shanghai Jinshan. The purity of the conductive carbon black used is 99.5%. The average particle size of the carbon black is 20nm - 40nm, and the resistivity of the carbon black is 0.05Ω / m.

[0199] Mix the above 90 parts of polypropylene S700 and 25 parts of carbon black using a mixer. Set the rotation speed of the mixer to 600r / min, the stirring temperature to 100℃, and the stirring time to 2h. After mixing evenly, convey the prepared mixed material to a twin-screw extruder for melt blending, and extrude it through the die head of the extruder. The extrusion temperature of the twin-screw extruder is: 120℃ in the feeding section, 225℃ for melting, 215℃ in the homogenization section, and the die head temperature is 220℃. After cooling and pelletizing, obtain masterbatch. Dry the masterbatch at 80℃ for 2 hours to remove the moisture in the masterbatch, and then add it to a screw extruder to form a uniform melt, and then carry out extrusion. Set the temperature of the feeding section of the screw extruder to 180℃, the temperature of the mixing section to 220℃, and the temperature of the extrusion section to 230℃. Then carry out meltblown to prepare a non-woven fabric base fabric. The temperature during die head spinning in the meltblown process is 230℃. Finally, send the non-woven fabric base fabric into a hot rolling machine for hot pressing treatment to prepare non-woven fabric C2. The thickness of the non-woven fabric is 1.0mm.

[0200] It should be noted that the melt needs to pass through a fine filter before entering the meltblown die head to remove possible impurities and unmolten particles, ensuring the purity and quality of the fibers. The melt is ejected at a high speed from the spinneret holes of the meltblown die head and is simultaneously strongly stretched by hot air to form ultrafine fibers. By adjusting the speed, temperature and direction of the hot air, the diameter, orientation and distribution of the fibers can be controlled. The ultrafine fibers are intertwined with each other in the air to form a network structure and are quickly cooled and solidified under the mixing action of hot air and the surrounding cold air to form a non-woven fabric base fabric with a certain thickness and strength.

[0201] The preparation process of the semiconductor resistive water buffer layer in this example includes:

[0202] A three-layer structured semiconductor water-resistant buffer layer, denoted as P4, is prepared by placing non-woven fabric C2 between adjacent conductive films B1 and B2 and then feeding it into a hot rolling machine for hot pressing. The hot pressing temperature of the hot rolling machine is 225 °C, the hot pressing pressure is 40 bar, and the thickness of the three-layer structured semiconductor water-resistant buffer layer prepared in this example is 1.2 mm.

[0203] Among the above-prepared three-layer structured semiconductor water-resistant buffer layers, the two conductive films can be the same or different. For example, the conductive film can be any one of the conductive films B1 to B3 prepared in Example 6, and the above effects can be achieved.

[0204] Example 9. Preparation of Semiconductor Water-Resistant Buffer Layer

[0205] The semiconductor water-resistant buffer layer prepared in this example has a three-layer structure, including two adjacent conductive films and non-woven fabric located between the two adjacent conductive films.

[0206] The preparation method of the non-woven fabric is as follows:

[0207] By mass fraction, the raw material feeding of the non-woven fabric is: 85 parts of polypropylene S700 and 20 parts of carbon black;

[0208] The polypropylene is polypropylene Z30S produced by Jinan Petrochemical. The purity of the conductive carbon black used is 99.5%, the average particle size of the carbon black is 20 nm - 40 nm, and the resistivity of the carbon black is 0.05 Ω / m.

[0209] Mix the above 90 parts of polypropylene S700 and 25 parts of carbon black using a mixer. Set the rotation speed of the mixer to 500 r / min, the mixing temperature to 100 °C, and the mixing time to 2 h. After mixing evenly, convey the prepared mixed material to a twin-screw extruder for melt blending, and extrude it through the die head of the extruder. The extrusion temperature of the twin-screw extruder is: 110 °C in the feeding section, 225 °C for melting, 210 °C in the homogenization section, and the die head temperature is 220 °C. After cooling and pelletizing, obtain masterbatch. Dry the masterbatch at 80 °C for 2 hours to remove the moisture in the masterbatch, and then add it to a screw extruder to form a uniform melt, and then perform extrusion. Set the temperature of the feeding section of the screw extruder to 180 °C, the temperature of the mixing section to 220 °C, and the temperature of the extrusion section to 230 °C. Then perform meltblowing to prepare a non-woven fabric base fabric. The temperature during die head spinning in the meltblowing process is 230 °C. Finally, send the non-woven fabric base fabric into a hot rolling machine for hot pressing treatment to prepare non-woven fabric C3. The thickness of the non-woven fabric is 1.2 mm.

[0210] It should be noted that the melt needs to pass through a fine filter before entering the meltblown die head to remove possible impurities and unmelted particles, ensuring the purity and quality of the fibers. The melt is ejected at high speed from the spinneret holes of the meltblown die head and is simultaneously strongly stretched by hot air to form ultrafine fibers. By adjusting the speed, temperature, and direction of the hot air, the diameter, orientation, and distribution of the fibers can be controlled. The ultrafine fibers are intertwined with each other in the air to form a network structure and are quickly cooled and solidified under the mixing action of the hot air and the surrounding cold air to form a non-woven base fabric with a certain thickness and strength.

[0211] The preparation process of the semiconductor resistive water buffer layer in this embodiment includes:

[0212] Place the non-woven fabric C3 between the adjacent conductive films B1 and B3, and then send it into a hot rolling machine for hot pressing treatment to prepare a three-layer structured semiconductor resistive water buffer layer, denoted as P5. The hot pressing temperature of the hot rolling machine is 220 °C, the hot pressing pressure is 35 bar, and the thickness of the three-layer structured semiconductor resistive water buffer layer prepared in this embodiment is 1.5 mm.

[0213] Among the two conductive films in the above-prepared three-layer structured semiconductor resistive water buffer layer, they can be the same or different. For example, the conductive film can be any one of the conductive films B1 to B3 prepared in Example 6, and the above effects can be achieved.

[0214] Example 10. Preparation of a cable

[0215] This embodiment provides a cable, which includes any one of the semiconductor resistive water buffer layers described in Examples 7 to 9, and the operating voltage of the cable is 110 kV or above.

[0216] Test Example 1. Performance test of the semiconductor resistive water buffer layer

[0217] In this test example, the semiconductor resistive water buffer layers prepared in Examples 7 to 9 are subjected to performance tests, including mechanical properties, electrical properties, water resistance properties, etc. The specific test indexes and methods are shown in Table 1:

[0218] Table 1: Test indexes and methods for the performance of the semiconductor resistive water buffer layer

[0219]

[0220] According to the test methods described in Table 1 above, the performance test results of the semiconductor resistive water buffer layers prepared in Examples 7 to 9 of the present invention are shown in Table 2:

[0221] Table 2: Performance test results of the semiconductor resistive water buffer layer

[0222]

[0223] The results obtained by the test method in Table 2 show that the semiconductive resistive water buffer layers prepared in Examples 7 to 9 of the present invention have good mechanical properties, electrical properties and stability, and in particular, the properties of P1, P4 and P5 are better.

[0224] Comparative Example 1

[0225] The composite conductive material prepared in this comparative example is basically the same as that in Example 1, except that: the polypropylene in the composition of the composite conductive material is different. In this comparative example, an equal amount of polypropylene K7100 with a low melt mass flow rate (purchased from Sinopec) is used for replacement, and its melt mass flow rate is 110 g / 10 min - 115 g / 10 min (measured according to GB / T3682, the measurement temperature is 230 °C, and the nominal load is 2.16 kg). The preparation methods of the remaining components are the same as those in Example 1.

[0226] Comparative Example 2

[0227] The composite conductive material prepared in this comparative example is basically the same as that in Example 1, except that: the addition amounts of polypropylene and nylon are different. In this comparative example, the addition amount of polypropylene T38 is 40 parts by mass, and that of nylon 66 is 40 parts by mass. The preparation methods of the remaining components are the same as those in Example 1.

[0228] Comparative Example 3

[0229] The composite conductive material prepared in this comparative example is basically the same as that in Example 1, except that: the addition amounts of polypropylene and nylon are different. In this comparative example, the addition amount of polypropylene T38 is 65 parts by mass, and that of nylon 66 is 15 parts by mass. The preparation methods of the remaining components are the same as those in Example 1.

[0230] Comparative Example 4

[0231] The composite conductive material prepared in this comparative example is basically the same as that in Example 1, except that: the addition amount of the chain extender is different. In this comparative example, the addition amount of the chain extender is 4 parts by mass (the chain extender is 1.35 parts by mass of ethylene glycol and 2.65 parts by mass of 1,2 - propanediol). The preparation methods of the remaining components are the same as those in Example 1.

[0232] Test Example 2. Performance Test of the Semiconductive Resistive Water Buffer Layer

[0233] In this test example, the composite conductive materials prepared in Comparative Examples 1 to 4 are respectively made into conductive films with a thickness of 0.1 mm by the method of Example 6, and further made into 4 groups of semiconductive resistive water buffer layers by the method of Example 7. The structure of the semiconductive resistive water buffer layer is: the conductive films of adjacent two layers are the conductive films prepared in the same comparative example, and the non - woven fabric located between adjacent two layers of conductive films is non - woven fabric C1;

[0234] Then, the performance test was carried out by using the test method of Test Example 1, and the results are shown in Table 3:

[0235] Table 3: Performance test results of the semiconductor resistive water buffer layer prepared by using the composite conductive materials of Comparative Examples 1-4

[0236]

[0237] As shown in the results of Table 3, the performance of the semiconductor resistive water buffer layer prepared by using the composite conductive materials of Comparative Examples 1-4 is significantly worse than that of the semiconductor resistive water buffer layer prepared in Examples 1-5. It can be seen that the melt mass flow rate of polypropylene in the composite conductive material and the addition amount of each raw material in the composite conductive material have a great influence on the prepared composite conductive material, and ultimately will affect the performance of the semiconductor resistive water buffer layer and the operation stability of the high-voltage cable.

[0238] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0239] The above-described embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be understood as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A composite conductive material, characterized in that: The raw materials for preparing the composite conductive material include 50-60 parts of polypropylene, 20-30 parts of nylon, 15-30 parts of carbon black and 5-10 parts of chain extender by weight; The melt mass flow rate of the polypropylene is 300 g / 10 min-1000 g / 10 min, and the melt mass flow rate of the polypropylene is measured at a temperature of 230° C. and a nominal load of 2.16 kg.

2. The composite conductive material according to claim 1, characterized in that: The composite conductive material satisfies at least one of the following (1) to (6): (1) The nylon in the composite conductive material is selected from one or more of nylon 66, nylon 6, nylon 11 and nylon 1010; (2) The particle size of the carbon black in the composite conductive material is 20nm-40nm; (3) The resistivity of the carbon black in the composite conductive material is 0.2Ω / m-0.4Ω / m; (4) The chain extender in the composite conductive material is selected from one or more of ethylene glycol, propylene glycol, butanediol and 2-methyl-1,3-propanediol; (5) The composite conductive material further comprises 0.5-2 parts by mass of an antioxidant; (6) The composite conductive material further comprises a hindered phenol antioxidant and / or a phosphite antioxidant.

3. A method for preparing a composite conductive material, characterized in that: The composite conductive material is the composite conductive material according to claim 1 or 2, and the preparation method comprises the following steps: The raw materials for preparing the composite conductive material are mixed to obtain a mixture, and the mixture is melt-extruded.

4. A conductive film, characterized in that: The composite conductive film comprises the composite conductive material according to any one of claims 1 to 2, or comprises a composite conductive material prepared by the preparation method according to claim 3.

5. A semiconducting resistive water buffer layer, characterized in that: The conductive water-repellent buffer layer satisfies the following conditions (1) or (2): (1) The conductive and water-repellent buffer layer comprises at least one layer of the conductive film according to claim 4; (2) The conductive and water-repellent buffer layer comprises at least one layer of the conductive film according to claim 4, and the thickness of the conductive film is 0.1 mm-0.15 mm.

6. The semiconducting water buffer layer according to claim 5, characterized in that: The conductive and water-repellent buffer layer further comprises a non-woven fabric, and the non-woven fabric is stacked with the conductive film.

7. The semiconducting water buffer layer according to claim 6, characterized in that: The raw materials for preparing the nonwoven fabric include polypropylene and carbon black; Optionally, the nonwoven fabric satisfies at least one of the following (1) to (6): (1) The melt mass flow rate of the polypropylene is 100 g / 10 min-1000 g / 10 min, and the measurement temperature of the melt mass flow rate of the polypropylene is 230° C. and the nominal load is 2.16 kg; (2) The carbon black is selected from conductive carbon black and / or acetylene carbon black; (3) The average particle size of the carbon black is 20nm-40nm; (4) The resistivity of the carbon black is 0.05Ω / m-0.2Ω / m; (5) The polypropylene is 80-90 parts by mass, and the carbon black is 20-25 parts by mass; (6) The thickness of the non-woven fabric is 0.8 mm to 1.2 mm.

8. The semiconductive water-repellent buffer layer according to any one of claims 5 to 7, characterized in that: The number of the conductive films is at least two, and the non-woven fabric is located between two adjacent layers of the conductive films.

9. A cable, characterized in that: The cable comprises the semiconducting resistive water buffer layer as described in any one of claims 5 to 8.

10. The cable according to claim 9, characterized in that: The operating voltage of the cable is 110 kV and above.

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