Shielding material composition, shielding material and preparation method thereof, shielding material and application thereof

Abstract

The present invention relates to the field of shielded cable materials, and discloses a shielding material composition, a shielding material and a preparation method thereof, a shielding material and an application thereof. The shielding material composition comprises, by weight, 69-82 parts of a base resin, 15-28 parts of conductive carbon black, 0.3-1.2 parts of polyaniline-functionalized carbon nanotubes, 0.5-1 parts of a cross-linking agent, 0.2-1 parts of a dispersant, 0.3-2.5 parts of a lubricant, and 0-1.5 parts of an antioxidant; wherein the polyaniline-functionalized carbon nanotubes comprise polyaniline and carbon nanotubes; the polyaniline and the carbon nanotubes are linked by a structure shown in Formula 1; #imgabs0# Formula 1; wherein Ar1 is a carbon nanotube and Ar2 is polyaniline. The shielding material made from the shielding material composition of the present invention has low resistivity and a low positive temperature coefficient while having good mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of shielded cable materials, and in particular to a shielding material composition, a shielding material and a preparation method thereof, a shielding material and an application thereof. Background Art

[0002] High-voltage cable semi-conductive shielding materials are typical composite materials filled with conductive fillers. Their resistivity increases with increasing temperature, a phenomenon known as the positive temperature coefficient (PTC) effect. This is primarily due to the volume expansion of the matrix resin caused by rising temperature, which disrupts the conductive network. Carbon nanotubes possess excellent mechanical, electrical, and thermal properties. Well-dispersed carbon nanotubes can stabilize the conductive network of the conductive polymer matrix and make it less susceptible to temperature effects, while also reducing the conductive filler content in the polymer. However, carbon nanotubes are prone to agglomeration, posing a challenge in achieving a uniform dispersion of carbon nanotubes in the matrix resin to reduce the resistivity and temperature resistance effect of the semi-conductive shielding material. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems of high resistivity and high positive temperature coefficient of shielding materials in the prior art, and to provide a shielding material composition, a shielding material and a preparation method thereof, a shielding material and an application thereof. The shielding material made from the shielding material composition of the present invention has low resistivity and low positive temperature coefficient while having good mechanical properties.

[0004] In order to achieve the above object, the first aspect of the present invention provides a shielding material composition, wherein the shielding material composition comprises, by weight:

[0005] 69-82 parts of base resin, 15-28 parts of conductive carbon black, 0.3-1.2 parts of polyaniline functionalized carbon nanotubes, 0.5-1 parts of crosslinking agent, 0.2-1 parts of dispersant, 0.3-2.5 parts of lubricant, 0-1.5 parts of antioxidant;

[0006] Wherein, the polyaniline functionalized carbon nanotubes comprise polyaniline and carbon nanotubes; the polyaniline and carbon nanotubes are linked by the structure shown in Formula 1;

[0007] Formula 1;

[0008] Wherein, Ar1 is carbon nanotube, and Ar2 is polyaniline.

[0009] A second aspect of the present invention provides a method for preparing a shielding material, wherein the preparation method comprises:

[0010] (1) Blending the components of the shielding material composition except the crosslinking agent to obtain a blend;

[0011] (2) The blend is pelletized and dried to obtain a semi-finished product;

[0012] (3) The semi-finished product is mixed with a cross-linking agent to obtain a shielding material.

[0013] A third aspect of the present invention provides a shielding material produced by the above method.

[0014] A fourth aspect of the present invention provides a shielding material, which is made by cross-linking the above-mentioned shielding material.

[0015] A fifth aspect of the present invention provides a use of the above-mentioned shielding material composition, or the above-mentioned shielding material, or the above-mentioned shielding material in a high-voltage power cable.

[0016] Through the above technical solution, the shielding material composition, shielding material and preparation method thereof, shielding material and application thereof provided by the present invention have the following beneficial effects.

[0017] The shielding material composition of the present invention includes polyaniline-functionalized carbon nanotubes with a specific structure, which can prevent the problem of carbon nanotube self-aggregation and clustering, and ensure good dispersion of the polyaniline-functionalized carbon nanotubes in the matrix. Furthermore, due to the synergistic effect between the specific amount of polyaniline-functionalized carbon nanotubes and other components, the shielding material made from the shielding material composition of the present invention not only has good mechanical properties, but also has low resistivity and a low positive temperature coefficient. DETAILED DESCRIPTION

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] A first aspect of the present invention provides a shielding material composition, wherein the shielding material composition comprises, by weight:

[0020] 69-82 parts of base resin, 15-28 parts of conductive carbon black, 0.3-1.2 parts of polyaniline functionalized carbon nanotubes, 0.5-1 parts of crosslinking agent, 0.2-1 parts of dispersant, 0.3-2.5 parts of lubricant, 0-1.5 parts of antioxidant;

[0021] Wherein, the polyaniline functionalized carbon nanotubes comprise polyaniline and carbon nanotubes; the polyaniline and carbon nanotubes are linked by the structure shown in Formula 1;

[0022] Formula 1;

[0023] Wherein, Ar1 is carbon nanotube, and Ar2 is polyaniline.

[0024] The shielding material composition of the present invention includes polyaniline-functionalized carbon nanotubes with a specific structure, which can prevent the problem of carbon nanotube self-aggregation and clustering, and ensure good dispersion of the polyaniline-functionalized carbon nanotubes in the matrix. Furthermore, due to the synergistic effect between the specific amount of polyaniline-functionalized carbon nanotubes and other components, the shielding material made from the shielding material composition of the present invention not only has good mechanical properties, but also has low resistivity and a low positive temperature coefficient.

[0025] Furthermore, the shielding material composition comprises, by weight: 72-79 parts of base resin, 18-25 parts of conductive carbon black, 0.5-1 parts of polyaniline functionalized carbon nanotubes, 0.5-1 parts of a crosslinking agent, 0.2-1 parts of a dispersant, 0.3-2.5 parts of a lubricant, and 0.5-1.5 parts of an antioxidant.

[0026] According to the present invention, the base resin is a polyolefin resin.

[0027] In the present invention, when the composition contains the above-mentioned type of matrix resin, the polyaniline-functionalized carbon nanotubes can be better dispersed in the matrix resin, and the shielding material made from the above-mentioned composition has lower resistivity and positive temperature coefficient.

[0028] Furthermore, the matrix resin is ethylene-acrylate resin and / or ethylene-acetate resin.

[0029] In the present invention, the type of the ethylene-acetate resin is not particularly limited. For example, the ethylene-acetate resin may be ethylene-vinyl acetate. Preferably, the content of vinyl acetate in the ethylene-vinyl acetate is 15-30 wt%.

[0030] Furthermore, the matrix resin is an ethylene-acrylate resin. For example, the matrix resin is an ethylene-butyl acrylate copolymer and / or an ethylene-ethyl acrylate copolymer. Preferably, the butyl acrylate content of the ethylene-butyl acrylate copolymer is 15-30 wt %; preferably, the ethyl acrylate content of the ethylene-ethyl acrylate copolymer is 10-20 wt %.

[0031] According to the present invention, the elongation at break of the matrix resin is ≥700%.

[0032] Furthermore, the elongation at break of the matrix resin is ≥800%.

[0033] According to the present invention, the base resin has a melt index of 5-10 g / 10 min at a temperature of 190° C. and a load of 2.16 kg.

[0034] In the present invention, when the melt index of the matrix resin meets the above range, the matrix resin has strong fluidity and is easy to process, which is beneficial to improving the bonding between the matrix resin and the conductive carbon black. The shielding material made of the above composition not only has good mechanical properties, but also has low resistivity and a low positive temperature coefficient.

[0035] Furthermore, the matrix resin has a melt index of 6-8 g / 10 min at a temperature of 190° C. and a load of 2.16 kg.

[0036] According to the present invention, the density of the matrix resin is 0.9-1g / cm 3 .

[0037] Furthermore, the density of the matrix resin is 0.9-0.95 g / cm 3 .

[0038] According to the present invention, the conductive carbon black is furnace black and / or acetylene black.

[0039] In the present invention, when the composition contains the above-mentioned conductive carbon black, the shielding material made from the composition has the characteristics of high conductivity and low resistivity.

[0040] Furthermore, the conductive carbon black is furnace black.

[0041] According to the present invention, the average particle size of the conductive carbon black is 30-60 nm.

[0042] In the present invention, when the average particle size of the conductive carbon black satisfies the above range, the shielding material prepared from the above composition has good dispersion of the conductive carbon black, a developed conductive path, high conductivity, and high mechanical properties.

[0043] Furthermore, the average particle size of the conductive carbon black is 30-50 nm.

[0044] According to the present invention, the cross-linking agent is an organic peroxide.

[0045] Furthermore, the cross-linking agent is di-tert-butylperoxyisopropylbenzene (BIBP) and / or diisopropylbenzene peroxide (DCP).

[0046] In the present invention, when the composition contains the above-mentioned cross-linking agent, the shielding material prepared from the composition has high cross-linking efficiency and better tensile properties of the cross-linked shielding material.

[0047] According to the present invention, the dispersant is a nonionic dispersant.

[0048] In the present invention, when the composition contains the above-mentioned type of dispersant, the conductive carbon black in the shielding material made from the above-mentioned composition is evenly dispersed, carbon black aggregation is reduced, and the generation of concentrated stress points is avoided, so that the shielding material has low resistivity and low positive temperature coefficient while having good mechanical properties.

[0049] Furthermore, the dispersant is polyethylene glycol and / or ethylene bisstearamide.

[0050] According to the present invention, the lubricant is selected from at least one of silicone oil, microcrystalline wax, polyethylene wax and zinc stearate.

[0051] In the present invention, when the composition contains the above-mentioned lubricant, the shielding material prepared from the composition has good processing performance and is not easy to burn during the crosslinking process, which is conducive to obtaining a shielding material with high mechanical properties, low resistivity and low positive temperature coefficient.

[0052] Furthermore, the lubricant is microcrystalline wax, or a combination of polyethylene wax and zinc stearate. Preferably, the mass ratio of polyethylene wax to zinc stearate is 1:0.5-2.

[0053] According to the present invention, the antioxidant is selected from at least one of amine antioxidants, thioester antioxidants, phosphite antioxidants and hindered phenol antioxidants.

[0054] In the present invention, the specific type of antioxidant is not particularly limited. Preferably, the antioxidant is selected from at least one of Antioxidant RD (amine antioxidant), Antioxidant 300 (thioester antioxidant), Antioxidant 168 (phosphite antioxidant), and Antioxidant 1010 (hindered phenol antioxidant). Preferably, the antioxidants are Antioxidant 168 and Antioxidant 1010. Preferably, the mass ratio of Antioxidant 168 to Antioxidant 1010 is 1:1-3.

[0055] According to the present invention, the polyaniline functionalized carbon nanotubes have an average length of 3-30 μm and an aspect ratio of 300-5000.

[0056] In the present invention, when the average length and / or aspect ratio of the polyaniline functionalized carbon nanotubes meet the above ranges, the shielding material made from the composition has strong conductivity, a stable conductive network, and low temperature effect.

[0057] Furthermore, the polyaniline functionalized carbon nanotubes have an average length of 3-20 μm and an aspect ratio of 300-2500.

[0058] Furthermore, the polyaniline functionalized carbon nanotubes have an average length of 10-20 μm and an aspect ratio of 1000-2000.

[0059] According to the present invention, the N content in the polyaniline-functionalized carbon nanotubes is 5-10 wt %.

[0060] In the present invention, when the nitrogen content of the polyaniline-functionalized carbon nanotubes meets the aforementioned range, it indicates a high grafting content of polyaniline on the carbon nanotubes and a high degree of polymerization of the polyaniline. The shielding material made from this composition exhibits good dispersion of the carbon nanotubes and a high degree of bonding with the matrix, resulting in the shielding material having not only excellent mechanical properties but also low resistivity and a low positive temperature coefficient.

[0061] Furthermore, the N content in the polyaniline-functionalized carbon nanotubes is 8-10 wt %.

[0062] According to a preferred embodiment of the present invention, the method for preparing polyaniline-functionalized carbon nanotubes comprises:

[0063] S1. After reacting the oxidized carbon nanotubes with thionyl chloride, p-phenylenediamine and pyridine are added under a protective atmosphere and stirred for a first time to obtain p-phenylenediamine-functionalized carbon nanotubes;

[0064] S2. dispersing p-phenylenediamine-functionalized carbon nanotubes and aniline in an acidic solution, adding an inorganic peroxide initiator and performing a second stirring, and post-treating the obtained product to obtain polyaniline-functionalized carbon nanotubes.

[0065] In the present invention, there is no particular limitation on the type of protective atmosphere, which may be at least one of a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere.

[0066] In the present invention, the carbon nanotubes are selected from multi-walled carbon nanotubes and / or single-walled carbon nanotubes.

[0067] According to a preferred embodiment of the present invention, the average length of the carbon nanotubes is 5-35 μm, and the aspect ratio is 500-6000; preferably, the average length of the carbon nanotubes is 5-25 μm, and the aspect ratio is 500-3500; more preferably, the average length of the carbon nanotubes is 12-25 μm, and the aspect ratio is 1500-3000.

[0068] In the present invention, the preparation method of oxidized carbon nanotubes is not particularly limited and can be prepared according to conventional oxidation methods in the art. Preferably, the carbon nanotubes are contacted with a solution containing an oxidant in the presence of a phase transfer catalyst. Preferably, the phase transfer catalyst is selected from methyltrioctylammonium chloride and / or hexadecyltrimethylammonium bromide. Preferably, the oxidant is selected from at least one of potassium permanganate, concentrated nitric acid, and hypochlorous acid. Preferably, the mass ratio of the carbon nanotubes, phase transfer catalyst, and oxidant is 1:5-15:30-60.

[0069] According to a preferred embodiment of the present invention, in step S1, the mass ratio of the oxidized carbon nanotubes to thionyl chloride is 1:50-100, preferably 1:80-100.

[0070] According to a preferred embodiment of the present invention, in step S1, the mass ratio of the oxidized carbon nanotubes to p-phenylenediamine is 1:0.5-10, preferably 1:1-5.

[0071] According to a preferred embodiment of the present invention, in step S1, the mass ratio of the oxidized carbon nanotubes to pyridine is 1:1-20, preferably 1:4-10.

[0072] According to a preferred embodiment of the present invention, in step S1, the reaction temperature is 60-90° C., and the reaction time is 18-36 hours.

[0073] According to a preferred embodiment of the present invention, in step S1, the temperature of the first stirring is 100-150° C., and the time of the first stirring is 1-5 days.

[0074] In the present invention, in step S1, after the oxidized carbon nanotubes react with thionyl chloride, excess thionyl chloride is removed.

[0075] In the present invention, there is no particular limitation on the method for removing thionyl chloride, and it can be any conventional method in the art, for example, distillation.

[0076] According to a preferred embodiment of the present invention, in step S2, the volume ratio of the p-phenylenediamine-functionalized carbon nanotubes to aniline is 5-30 g / 100 mL, preferably 10-20 g / 100 mL, and more preferably 10-16 g / 100 mL.

[0077] In the present invention, there is no particular limitation on the specific type of the acidic solution. For example, the acidic solution may be hydrochloric acid. In the present invention, there is no particular requirement for the concentration of the acidic solution. Preferably, the pH value of the acidic solution is 1-2.

[0078] According to a preferred embodiment of the present invention, in step S2, the mass ratio of the p-phenylenediamine functionalized carbon nanotubes to the inorganic peroxide initiator is 1:5-20, preferably 1:10-15.

[0079] According to a preferred embodiment of the present invention, in step S2, the temperature of the second stirring is 10-30°C, and the time of the second stirring is 3-10 hours.

[0080] In the present invention, there is no particular limitation on the dispersion in step S2. For example, the dispersion can be performed by ultrasonication.

[0081] In the present invention, in step S2, an inorganic peroxide is added under stirring conditions.

[0082] In the present invention, in step S2, the post-treatment includes: washing and filtering with a first washing solution, and then washing and drying with a second washing solution.

[0083] Preferably, the first washing solution is selected from hydrochloric acid and / or nitric acid.

[0084] Preferably, the second washing solution is water and acetone.

[0085] A second aspect of the present invention provides a method for preparing a shielding material, wherein the preparation method comprises:

[0086] (1) Blending the components of the shielding material composition except the crosslinking agent to obtain a blend;

[0087] (2) The blend is pelletized and dried to obtain a semi-finished product;

[0088] (3) The semi-finished product is mixed with a cross-linking agent to obtain a shielding material.

[0089] According to the present invention, in step (1), the blending conditions include: the blending conditions include: the blending feeding section temperature T1 is 100-150°C, the blending mixing section temperature T2 is 240-270°C, and the blending extrusion section temperature T3 is 250-280°C.

[0090] In the present invention, when the blending conditions meet the above ranges, it is beneficial to obtain a shielding material with high mechanical properties, low resistivity and low positive temperature coefficient.

[0091] Furthermore, in step (1), T2≤T3.

[0092] In the present invention, in step (1), the blending conditions include: the rotation speed of the extruder is 300-400 rpm.

[0093] In the present invention, in step (1), the blending device is a single-screw extruder.

[0094] In the present invention, in step (2), there is no particular limitation on the method of pelletizing, and pelletizing can be performed in a conventional manner in the art. For example, pelletizing can be performed using a pelletizer.

[0095] In the present invention, there is no particular limitation on the drying conditions in step (2), and conventional drying conditions in the art may be used. Preferably, the drying temperature is 50-60° C., and the drying time is 1-2 h.

[0096] According to the present invention, in step (3), the cross-linking agent is melted and then mixed with the semi-finished product.

[0097] According to the present invention, the mixing temperature is 60-80° C., and the mixing time is 10-60 minutes.

[0098] Furthermore, the mixing temperature is 60-70° C., and the mixing time is 10-40 minutes.

[0099] In the present invention, the cross-linking agent is melted and then mixed with the semi-finished product in a post-absorption device. Preferably, the rolling speed of the post-absorption device is 1-10 rpm, preferably 1-5 rpm.

[0100] A third aspect of the present invention provides a shielding material produced by the above method.

[0101] A fourth aspect of the present invention provides a shielding material, which is made by cross-linking the above-mentioned shielding material.

[0102] According to the present invention, the tensile strength of the shielding material is greater than or equal to 15 MPa.

[0103] According to the present invention, the elongation at break of the shielding material is greater than or equal to 250%.

[0104] According to the present invention, the resistivity of the shielding material at 23° C. is less than or equal to 20Ω·cm.

[0105] Furthermore, the resistivity of the shielding material at 23° C. is less than or equal to 15Ω·cm.

[0106] According to the present invention, the resistivity of the shielding material at 90° C. is less than or equal to 100Ω·cm.

[0107] Furthermore, the resistivity of the shielding material at 90° C. is less than or equal to 90Ω·cm.

[0108] In the present invention, the positive temperature coefficient of the shielding material is less than or equal to 10.

[0109] In the present invention, the positive temperature coefficient of the shielding material refers to the ratio of the resistivity of the shielding material at 90°C to the resistivity at 23°C.

[0110] Furthermore, the positive temperature coefficient of the shielding material is less than or equal to 4.5.

[0111] A fifth aspect of the present invention provides a use of the above-mentioned shielding material composition, or the above-mentioned shielding material, or the above-mentioned shielding material in a high-voltage power cable.

[0112] In a preferred embodiment of the present invention, the high-voltage power cable is an AC cable.

[0113] The present invention will be described in detail below through examples.

[0114] In the following examples and comparative examples:

[0115] Melt index of the matrix resin: measured according to the method specified in GB / T 3682-2000, wherein the test temperature is 190°C and the load is 2.16 kg.

[0116] Average particle size of conductive carbon black: obtained by transmission electron microscopy (TEM).

[0117] Average length and aspect ratio of polyaniline functionalized carbon nanotubes: The average length was obtained by scanning electron microscopy (SEM), and the aspect ratio was obtained by transmission electron microscopy (TEM).

[0118] Nitrogen content in polyaniline-functionalized carbon nanotubes: obtained by X-ray photoelectron spectroscopy (XPS).

[0119] Tensile strength and elongation at break: measured in accordance with the method specified in GB / T 1040.3-2022, using Type A specimens.

[0120] Resistivity: Determined in accordance with the method specified in Part 3 Volume Resistivity Test of Semi-Conductive Rubber and Plastic Materials in GB / T 3048-2007.

[0121] PTC coefficient: the ratio of the resistivity of the shielding material at 90°C to the resistivity at 23°C.

[0122] Surface protrusion: Tested with an optical scanning device with a high-resolution camera, with a scanning speed of 0.05m 2 / min, the surface of the sample strip is scanned by a high-resolution camera, and the size and number of surface protrusions are characterized based on the total surface area of ​​about 1m 2 For samples, record the number of surface protrusions with a height greater than or equal to 50 μm.

[0123] Ethylene butyl acrylate (EBA): a commercial product sold by Repsol under the brand name E1770; melt index at 190°C and 2.16 kg: 7 g / 10 min, elongation at break: 800%, density: 0.924 g / cm 3 , the content of butyl acrylate is 17wt%.

[0124] Ethylene ethyl acrylate (EEA): commercially available from DuPont under the designation 2715; melt index 7 g / 10 min at 190°C and 2.16 kg, elongation at break 800%, density 0.93 g / cm 3 , the content of ethyl acrylate is 15%.

[0125] Ethylene vinyl acetate (EVA): Mitsui brand EVA P2805, with a melt index of 7 g / 10 min at 190°C and 2.16 kg, an elongation at break of 800%, and a density of 0.93 g / cm 3 , the vinyl acetate content is 28%.

[0126] Conductive carbon black: furnace black, average particle size is 35nm; acetylene black, average particle size is 45nm.

[0127] Dispersant: polyethylene glycol PEG10000, a commercial product of TEGO Corporation with the trade name TEGO Dispers 760W.

[0128] Dispersant: Ethylene bisstearamide (EBS), a commercial product of Aladdin with product number N159314.

[0129] Antioxidants: Antioxidant 168 and antioxidant 1010 were purchased from Xinxiang New Materials Co., Ltd., and the mass ratio of antioxidant 168 to antioxidant 1010 was 1:2.

[0130] Antioxidant: Antioxidant RD was purchased from Sinopec Nanjing Chemical Industry Co., Ltd.

[0131] Lubricant: zinc stearate and PE cracking wax, the mass ratio of Aladdin's zinc stearate to Onkar's PE cracking wax is 1:1.

[0132] Other raw materials used in the examples and comparative examples are all commercially available.

[0133] In the examples and comparative examples, the room temperature is 23°C.

[0134] Preparation Example 1

[0135] Carbon nanotubes (multi-walled carbon nanotubes, with an average length of 25 μm and an aspect ratio of 3000) were oxidized using potassium permanganate in the presence of methyltrioctylammonium chloride to obtain oxidized carbon nanotubes (o-MWNTs). The mass ratio of the carbon nanotubes, phase transfer catalyst, and oxidant was 1:10:50.

[0136] o-MWNTs were refluxed with thionyl chloride at 80°C for 24 hours, followed by removal of excess thionyl chloride and addition of p-phenylenediamine and pyridine. The mixture was stirred at 120°C under a nitrogen atmosphere for 3 days to yield p-phenylenediamine-functionalized carbon nanotubes (α-MWNTs). The mass ratio of oxidized carbon nanotubes to thionyl chloride was 1:90, and the mass ratio of oxidized carbon nanotubes to p-phenylenediamine to pyridine was 1:4:8.

[0137] α-MWNTs and aniline were dispersed in hydrochloric acid (pH 2) by ultrasonic treatment. Ammonium persulfate was slowly added with stirring, and stirring was continued at room temperature for 5 hours. The mass ratio of p-phenylenediamine-functionalized carbon nanotubes to aniline volume was 15 g / 100 mL, and the mass ratio of p-phenylenediamine-functionalized carbon nanotubes to inorganic peroxide initiator was 1:12.

[0138] The unreacted oxidant and monomer were then washed with hydrochloric acid, and the dark green product was filtered, washed with water and acetone in sequence, and dried to obtain polyaniline-functionalized carbon nanotubes A. The test results of polyaniline-functionalized carbon nanotubes A are shown in Table 1.

[0139] Preparation Example 2

[0140] Carbon nanotubes (multi-walled carbon nanotubes, with an average length of 25 μm and an aspect ratio of 3000) were oxidized using potassium permanganate in the presence of methyltrioctylammonium chloride to obtain oxidized carbon nanotubes (o-MWNTs). The mass ratio of the carbon nanotubes, phase transfer catalyst, and oxidant was 1:10:50.

[0141] o-MWNTs were refluxed with thionyl chloride at 80°C for 24 hours, followed by removal of excess thionyl chloride and addition of p-phenylenediamine and pyridine. The mixture was stirred at 120°C under a nitrogen atmosphere for 3 days to yield p-phenylenediamine-functionalized carbon nanotubes (α-MWNTs). The mass ratio of oxidized carbon nanotubes to thionyl chloride was 1:90, and the mass ratio of oxidized carbon nanotubes to p-phenylenediamine to pyridine was 1:4:8.

[0142] α-MWNTs and aniline were dispersed in hydrochloric acid (pH 2) by ultrasonic treatment. Ammonium persulfate was slowly added with stirring, and stirring was continued at room temperature for 5 hours. The mass ratio of p-phenylenediamine-functionalized carbon nanotubes to aniline volume was 25 g / 100 mL, and the mass ratio of p-phenylenediamine-functionalized carbon nanotubes to inorganic peroxide initiator was 1:12.

[0143] The unreacted oxidant and monomer were then washed with hydrochloric acid, and the dark green product was filtered, washed with water and acetone in sequence, and dried to obtain polyaniline-functionalized carbon nanotubes B. The test results of polyaniline-functionalized carbon nanotubes B are shown in Table 1.

[0144] Preparation Example 3

[0145] Carbon nanotubes (multi-walled carbon nanotubes, with an average length of 25 μm and an aspect ratio of 3000) were oxidized using potassium permanganate in the presence of methyltrioctylammonium chloride to obtain oxidized carbon nanotubes (o-MWNTs). The mass ratio of the carbon nanotubes, phase transfer catalyst, and oxidant was 1:10:50.

[0146] o-MWNTs were refluxed with thionyl chloride at 80°C for 24 hours, followed by removal of excess thionyl chloride and addition of p-phenylenediamine and pyridine. The mixture was stirred at 70°C under a nitrogen atmosphere for 24 hours to yield p-phenylenediamine-functionalized carbon nanotubes (α-MWNTs). The mass ratio of oxidized carbon nanotubes to thionyl chloride was 1:819, and the mass ratio of oxidized carbon nanotubes to p-phenylenediamine to pyridine was 1:20:8.

[0147] Disperse α-MWNTs and aniline in hydrochloric acid (pH 2) by ultrasonic treatment. Slowly add ammonium persulfate while stirring, and continue stirring at room temperature for 1 hour. The mass ratio of p-phenylenediamine-functionalized carbon nanotubes to aniline volume is 20g / 100mL, and the mass ratio of p-phenylenediamine-functionalized carbon nanotubes to inorganic peroxide initiator is 1:123.

[0148] The unreacted oxidant and monomer were then washed with hydrochloric acid, and the dark green product was filtered, washed with water and acetone in sequence, and dried to obtain polyaniline-functionalized carbon nanotubes C. The test results of polyaniline-functionalized carbon nanotubes C are shown in Table 1.

[0149] Preparation Example 4

[0150] Carbon nanotubes (multi-walled carbon nanotubes, with an average length of 5 μm and an aspect ratio of 600) were oxidized using potassium permanganate in the presence of methyltrioctylammonium chloride to obtain oxidized carbon nanotubes (o-MWNTs). The mass ratio of the carbon nanotubes, phase transfer catalyst, and oxidant was 1:10:50.

[0151] o-MWNTs were refluxed with thionyl chloride at 80°C for 24 hours, followed by removal of excess thionyl chloride and addition of p-phenylenediamine and pyridine. The mixture was stirred at 120°C under a nitrogen atmosphere for 3 days to yield p-phenylenediamine-functionalized carbon nanotubes (α-MWNTs). The mass ratio of oxidized carbon nanotubes to thionyl chloride was 1:90, and the mass ratio of oxidized carbon nanotubes to p-phenylenediamine to pyridine was 1:4:8.

[0152] α-MWNTs and aniline were dispersed in hydrochloric acid (pH 2) by ultrasonic treatment. Ammonium persulfate was slowly added with stirring, and stirring was continued at room temperature for 5 hours. The mass ratio of p-phenylenediamine-functionalized carbon nanotubes to aniline volume was 15 g / 100 mL, and the mass ratio of p-phenylenediamine-functionalized carbon nanotubes to inorganic peroxide initiator was 1:12.

[0153] The unreacted oxidant and monomer were then washed with hydrochloric acid, and the dark green product was filtered, washed with water and acetone in sequence, and dried to obtain polyaniline-functionalized carbon nanotubes D. The test results of polyaniline-functionalized carbon nanotubes D are shown in Table 1.

[0154] Preparation Example 5

[0155] Carbon nanotubes (multi-walled carbon nanotubes, with an average length of 28 μm and an aspect ratio of 3400) were oxidized using potassium permanganate in the presence of methyltrioctylammonium chloride to obtain oxidized carbon nanotubes (o-MWNTs). The mass ratio of the carbon nanotubes, phase transfer catalyst, and oxidant was 1:10:50.

[0156] o-MWNTs were refluxed with thionyl chloride at 80°C for 24 hours, followed by removal of excess thionyl chloride and addition of p-phenylenediamine and pyridine. The mixture was stirred at 120°C under a nitrogen atmosphere for 3 days to yield p-phenylenediamine-functionalized carbon nanotubes (α-MWNTs). The mass ratio of oxidized carbon nanotubes to thionyl chloride was 1:90, and the mass ratio of oxidized carbon nanotubes to p-phenylenediamine to pyridine was 1:4:8.

[0157] α-MWNTs and aniline were dispersed in hydrochloric acid (pH 2) by ultrasonic treatment. Ammonium persulfate was slowly added with stirring and continued at room temperature for 5 hours. The mass ratio of p-phenylenediamine-functionalized carbon nanotubes to aniline volume was 8 g / 100 mL, and the mass ratio of p-phenylenediamine-functionalized carbon nanotubes to inorganic peroxide initiator was 1:12.

[0158] The unreacted oxidant and monomer were then washed with hydrochloric acid, and the dark green product was filtered, washed with water and acetone in sequence, and dried to obtain polyaniline-functionalized carbon nanotubes E. The test results of polyaniline-functionalized carbon nanotubes E are shown in Table 1.

[0159] Comparative Preparation Example 1

[0160] Carbon nanotubes (multi-walled carbon nanotubes, with an average length of 25 μm and an aspect ratio of 3000) were oxidized using potassium permanganate in the presence of methyltrioctylammonium chloride to obtain oxidized carbon nanotubes (o-MWNTs). The mass ratio of the carbon nanotubes, phase transfer catalyst, and oxidant was 1:10:50.

[0161] Disperse o-MWNTs and aniline in hydrochloric acid (pH 2) by ultrasonication. Slowly add ammonium persulfate while stirring, and continue stirring at room temperature for 5 hours. The mass ratio of p-phenylenediamine-functionalized carbon nanotubes to aniline volume is 15 g / 100 mL, and the mass ratio of p-phenylenediamine-functionalized carbon nanotubes to inorganic peroxide initiator is 1:12.

[0162] Subsequently, the unreacted oxidant and monomer were washed with hydrochloric acid, and the dark green product was filtered, washed with water and acetone in sequence, and dried to obtain polyaniline-functionalized carbon nanotubes X.

[0163] Table 1

[0164]

[0165] Example 1

[0166] The raw materials used in this example are, by weight, 72 parts base resin, 25 parts conductive carbon black, 0.5 parts polyaniline-functionalized carbon nanotubes, 0.5 parts dispersant, 0.5 parts lubricant, 0.5 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection.

[0167] The preparation process is as follows:

[0168] (1) The matrix resin, conductive carbon black, antioxidant, polyaniline functionalized carbon nanotubes, dispersant, and lubricant were added to a reciprocating single-screw extruder for blending. The main engine speed was 300 rpm, the temperature of the front feeding section was 100°C, the temperature of the middle mixing section was 240°C, and the temperature of the rear extrusion section was 250°C.

[0169] (2) The obtained blend is pelletized by a pelletizer and then dried. The drying process conditions are: drying temperature 50°C, drying time 2h, to obtain a semi-finished product;

[0170] (3) The semi-finished product is sent to the post-absorption system for cross-linking agent absorption, and then sent to the powder removal system to remove the powder to obtain the shielding material. The process conditions of the post-absorption system are: cross-linking agent temperature 60°C, rolling speed 5 rpm, and rolling time 10 minutes.

[0171] Example 2

[0172] The raw materials used in this example are, by weight, 79 parts base resin, 18 parts conductive carbon black, 1 part polyaniline-functionalized carbon nanotubes, 0.2 parts dispersant, 0.3 parts lubricant, 0.5 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection.

[0173] The preparation process is as follows:

[0174] (1) The matrix resin, conductive carbon black, antioxidant, polyaniline functionalized carbon nanotubes, dispersant, and lubricant were put into a reciprocating single-screw extruder for blending. The main engine speed was 400 rpm, the temperature of the front feeding section was 150°C, the temperature of the middle mixing section was 270°C, and the temperature of the rear extrusion section was 280°C.

[0175] (2) The obtained blend is pelletized by a pelletizer and then dried. The drying process conditions are: drying temperature 60°C, drying time 1 hour, to obtain a semi-finished product;

[0176] (3) The semi-finished product is sent to the post-absorption system for cross-linking agent absorption, and then sent to the powder removal system to remove the powder to obtain the shielding material. The process conditions of the post-absorption system are: cross-linking agent temperature 70°C, rolling speed 1 rpm, and rolling time 40 min.

[0177] Example 3

[0178] The raw materials used in this example, by weight, are: 73 parts base resin, 23 parts conductive carbon black, 0.8 parts polyaniline-functionalized carbon nanotubes, 0.5 parts dispersant, 0.7 parts lubricant, 0.1 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection. The shielding material preparation process is the same as in Example 1.

[0179] Example 4

[0180] The raw materials used in this example, by weight, are: 75 parts base resin, 20 parts conductive carbon black, 1 part polyaniline-functionalized carbon nanotubes, 0.7 parts dispersant, 1 part lubricant, 1.3 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection. The shielding material preparation process is the same as in Example 1.

[0181] Examples 5-12

[0182] The shielding material was prepared according to the method of Example 1. The specific raw material selection is shown in Table 2.

[0183] Comparative Example 1

[0184] The raw materials used in this example, by weight, are: 63 parts base resin, 34 parts conductive carbon black, 0.5 parts polyaniline-functionalized carbon nanotubes, 0.5 parts dispersant, 0.5 parts lubricant, 0.5 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection. The shielding material preparation process is the same as in Example 1.

[0185] Comparative Example 2

[0186] The raw materials used in this example, by weight, are: 85 parts base resin, 12 parts conductive carbon black, 0.5 parts polyaniline-functionalized carbon nanotubes, 0.5 parts dispersant, 0.5 parts lubricant, 0.5 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection. The shielding material preparation process is the same as in Example 1.

[0187] Comparative Example 3

[0188] The raw materials used in this example, by weight, are: 73 parts base resin, 24 parts conductive carbon black, 1.5 parts polyaniline-functionalized carbon nanotubes, 0.5 parts dispersant, 0.5 parts lubricant, 0.5 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection. The shielding material preparation process is the same as in Example 1.

[0189] Comparative Example 4

[0190] The raw materials used in this example, by weight, are: 75 parts base resin, 20.4 parts conductive carbon black, 0.1 parts polyaniline-functionalized carbon nanotubes, 0.7 parts dispersant, 1 part lubricant, 1.3 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection. The shielding material preparation process is the same as in Example 1.

[0191] Comparative Example 5

[0192] The raw materials used in this example, by weight, are: 75 parts base resin, 20.5 parts conductive carbon black, 0.7 parts dispersant, 1 part lubricant, 1.3 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific selection of raw materials. The shielding material preparation process is the same as in Example 1.

[0193] Comparative Example 6

[0194] The raw materials used in this example, by weight, are: 72 parts base resin, 25 parts conductive carbon black, 0.5 parts polyaniline-functionalized carbon nanotubes, 0.5 parts dispersant, 0.5 parts lubricant, 0.5 parts antioxidant, and 1 part crosslinking agent. See Table 2 for the specific raw material selection. The shielding material preparation process is the same as in Example 1.

[0195] Table 2

[0196]

[0197] Table 2

[0198]

[0199] Table 2

[0200]

[0201] Test Case

[0202] The shielding materials obtained in the examples and comparative examples were pressed into shielding materials (180°C, 15 min). The tensile strength, elongation at break, volume resistivity at room temperature, volume resistivity at 90°C, and PTC coefficient of the shielding materials were tested and the test results are shown in Table 3.

[0203] Table 3

[0204]

[0205] *Performance indicators: Performance requirements for semi-conductive shielding materials in Appendix B of GB / T 18890.2-2015.

[0206] From the results in Table 3, it can be seen that the shielding material made from the shielding material composition of the present invention meets the requirements of GB / T 18890.2-2015. While the elongation at break is greater than or equal to 250%, the volume resistivity at 23°C is less than 20Ω·cm, and the volume resistivity at 90°C is less than 100Ω·cm. It can be seen that the shielding material has high mechanical properties and low volume resistivity, and the PTC coefficient is lower, and there is no surface protrusion greater than 50μm.

[0207] Compared to Example 1, Comparative Example 1 excessively reduced the matrix resin content and increased the conductive carbon black content. This low matrix resin content disrupted the flexibility-rigidity balance between the resin and the polyaniline-functionalized carbon nanotubes, reducing the shielding material's flexibility. The increased conductive carbon black content resulted in poor dispersibility and increased agglomeration. Consequently, Comparative Example 1 exhibited a low elongation at break, failing to meet the requirements of GB / T 18890.2-2015. Furthermore, the PTC coefficient was high, and surface protrusions larger than 50 μm were present.

[0208] Compared with Example 1, Comparative Example 2 excessively increased the content of the base resin and reduced the content of the conductive carbon black, resulting in an underdeveloped conductive network in the shielding material, a weak distributed conductive network, a significant increase in the volume resistivity, and failure to meet the requirements of GB / T18890.2-2015, and a high PTC coefficient.

[0209] Compared with Example 1, Comparative Example 3 excessively increased the content of polyaniline-functionalized carbon nanotubes, resulting in a break in the balance between flexibility and rigidity between the resin and the polyaniline-functionalized carbon nanotubes, a reduction in the flexibility of the shielding material, and failure to meet the requirements of GB / T 18890.2-2015, and the presence of surface protrusions greater than 50 μm.

[0210] Compared to Example 2, Comparative Examples 4 and 5 excessively reduced the polyaniline-functionalized carbon nanotube content, failing to enhance the conductivity of the shielding material. Furthermore, the carbon black content was too low, resulting in an underdeveloped and weakly distributed conductive network. The bulk resistivity was high, failing to meet the requirements of GB / T 18890.2-2015, and the PTC coefficient was high.

[0211] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A shielding material composition, characterized in that: The shielding material composition comprises, by weight: 69-82 parts of base resin, 15-28 parts of conductive carbon black, 0.3-1.2 parts of polyaniline functionalized carbon nanotubes, 0.5-1 parts of crosslinking agent, 0.2-1 parts of dispersant, 0.3-2.5 parts of lubricant, 0-1.5 parts of antioxidant; Wherein, the polyaniline functionalized carbon nanotubes comprise polyaniline and carbon nanotubes; the polyaniline and carbon nanotubes are linked by the structure shown in Formula 1; Formula 1; Wherein, Ar1 is a carbon nanotube, Ar2 is polyaniline, and the N content in the polyaniline functionalized carbon nanotube is 5-10 wt%.

2. The shielding material composition according to claim 1, wherein The base resin is a polyolefin resin; and / or, the elongation at break of the matrix resin is ≥700%; and / or, the matrix resin has a melt index of 5-10 g / 10 min at a temperature of 190° C. and a load of 2.16 kg; And / or, the density of the matrix resin is 0.9-1g / cm 3 .

3. The shielding material composition according to claim 1 or 2, wherein: The conductive carbon black is furnace black and / or acetylene black; And / or, the average particle size of the conductive carbon black is 30-60 nm; and / or, the cross-linking agent is an organic peroxide; and / or, the dispersant is a nonionic dispersant; and / or, the lubricant is selected from at least one of silicone oil, microcrystalline wax, polyethylene wax and zinc stearate; And / or, the antioxidant is selected from at least one of amine antioxidants, thioester antioxidants, phosphite antioxidants and hindered phenol antioxidants.

4. The shielding material composition according to claim 1 or 2, wherein The polyaniline functionalized carbon nanotubes have an average length of 3-30 μm and an aspect ratio of 300-5000.

5. The shielding material composition according to claim 1 or 2, wherein The preparation method of the polyaniline functionalized carbon nanotubes comprises: S1. After reacting the oxidized carbon nanotubes with thionyl chloride, p-phenylenediamine and pyridine are added under a protective atmosphere and stirred for a first time to obtain p-phenylenediamine-functionalized carbon nanotubes; S2. dispersing p-phenylenediamine-functionalized carbon nanotubes and aniline in an acidic solution, adding an inorganic peroxide initiator and performing a second stirring, and post-treating the obtained product to obtain polyaniline-functionalized carbon nanotubes.

6. The shielding material composition according to claim 5, wherein In step S1, the mass ratio of the oxidized carbon nanotubes to thionyl chloride is 1:50-100; And / or, in step S1, the mass ratio of the oxidized carbon nanotubes to p-phenylenediamine is 1:0.5-10; And / or, in step S1, the mass ratio of the oxidized carbon nanotubes to pyridine is 1:1-20; And / or, in step S1, the first stirring temperature is 100-150° C., and the first stirring time is 1-5 days; and / or, in step S2, the mass ratio of the p-phenylenediamine-functionalized carbon nanotubes to the volume ratio of aniline is 5-30 g / 100 mL; And / or, in step S2, the temperature of the second stirring is 10-30°C, and the time of the second stirring is 3-10 hours.

7. A method for preparing a shielding material, characterized in that: The preparation method comprises: (1) Blending the components of the shielding material composition according to any one of claims 1 to 6 except the crosslinking agent to obtain a blend; (2) The blend is pelletized and dried to obtain a semi-finished product; (3) The semi-finished product is mixed with a cross-linking agent to obtain a shielding material.

8. The preparation method according to claim 7, wherein In step (1), the blending conditions include: the temperature of the feeding section T1 of the blending is 100-150°C, the temperature of the mixing section T2 of the blending is 240-270°C, and the temperature of the extrusion section T3 of the blending is 250-280°C; And / or, in step (3), the cross-linking agent is melted and then mixed with the semi-finished product; And / or, the mixing temperature is 60-80° C., and the mixing time is 10-60 min.

9. A shielding material produced by the preparation method according to claim 7 or 8.

10. A shielding material, characterized in that: The shielding material according to claim 9 is made by cross-linking.

11. The shielding material according to claim 10, wherein The tensile strength of the shielding material is greater than or equal to 15 MPa; and / or, the shielding material has an elongation at break greater than or equal to 250%; and / or, the resistivity of the shielding material at 23° C. is less than or equal to 20Ω·cm; And / or, the resistivity of the shielding material at 90° C. is less than or equal to 100Ω·cm.

12. Use of the shielding material composition according to any one of claims 1 to 6, or the shielding material according to claim 9, or the shielding material according to claim 10 or 11 in a high-voltage power cable.

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