Soft high-voltage-resistant insulated wire material for automobile and preparation method of soft high-voltage-resistant insulated wire material

Abstract

The invention discloses a soft high-voltage-resistant insulated wire material for an automobile and a preparation method of the soft high-voltage-resistant insulated wire material, belongs to the technical field of wire material processing, and is used for solving the technical problem that in the prior art, the mechanical property and the high-voltage-resistant insulating property of the wire material for the automobile need to be further improved. The modified cross-linked polyethylene cable material specifically comprises the following components in parts by weight: 60-80 parts of modified cross-linked polyethylene, 8-12 parts of a modified plasticizer, 15-25 parts of a filler aid and 1-3 parts of an additive, wherein the additive is composed of silicone master batch and stearoylbenzoylmethane in a weight ratio of 3: 1. The mechanical property and the high-voltage-resistant insulating property of the material are improved by combining the insulating property of the modified cross-linked polyethylene with the high heat resistance of the polyimide and balancing the flexibility of the plasticizer and the rigidity of the polyimide.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of wire material processing, in particular to a soft high-pressure-resistant insulating wire material for automobiles and a preparation method thereof. BACKGROUND

[0002] In the process of accelerating the electrification and intelligentization of the automobile industry, the importance of the soft high-pressure-resistant insulating wire material for automobiles is increasingly highlighted. With the vigorous development of new energy vehicles, especially the wide application of high-voltage platforms, strict requirements are put forward for the performance of the wire material. Polyethylene has the advantages of high insulation resistance, good voltage resistance, small dielectric constant and dielectric loss, and is one of the preferred materials for medium and low voltage cable insulation.

[0003] Although ordinary polyethylene has good softness, its heat distortion temperature is low. Although the crosslinking of crosslinked polyethylene can improve the heat distortion temperature, the crosslinking process will lead to an increase in the hardness of the material and a decrease in the flexibility. The contradiction between the mechanical properties and the heat resistance makes it difficult for the traditional polyethylene material to meet the requirements of high-temperature resistance and softness of the automobile high-voltage wire.

[0004] In order to improve the flexibility and high-temperature resistance of the wire material, other auxiliary materials are usually used to enhance the polyethylene. However, the difference in properties between the materials leads to poor compatibility between the molecules of the prepared wire material, and the mechanical strength, voltage resistance and other properties of the material need to be further improved.

[0005] In addition, during the use of the wire material, the additives migrate, volatilize or chemically react with the polymer molecules, destroying the original molecular structure and performance balance and further exacerbating the degradation of the performance of the wire material, greatly shortening the service life of the wire material. SUMMARY

[0006] The application aims to provide a soft high-pressure-resistant insulating wire material for automobiles and a preparation method thereof, which can solve the technical problem that the mechanical properties and high-pressure-resistant insulating properties of the wire material for automobiles need to be further improved.

[0007] The application can be realized by the following technical scheme: a soft high-pressure-resistant insulating wire material for automobiles, which comprises the following components in parts by weight: modified crosslinked polyethylene 60-80 parts, modified plasticizer 8-12 parts, filler additive 15-25 parts and additive 1-3 parts, wherein the additive is composed of silicone masterbatch and stearylbenzoyl methane in a weight ratio of 3:1.

[0008] The preparation method of the modified cross-linked polyethylene is as follows: the high-pressure polyethylene is added into a rheometer, the temperature of the rheometer is set to 200-300 DEG C, the rotating speed is 50-60 rpm, the antioxidant 1010 is added, the cross-linked polyethylene precursor is added, and the mixing is carried out for 3-5 min; the rheometer is set to 110-120 DEG C, the rotating speed is 50-60 rpm, the dicumyl peroxide is added into the system, and the mixing is carried out for 2-3 min, so as to obtain the modified cross-linked polyethylene.

[0009] The synthesis mechanism of the modified cross-linked polyethylene is as follows:

[0010]

[0011] The dicumyl peroxide is decomposed to generate alkyl radicals, the alkyl radicals are used to take hydrogen atoms from the polymer chain to generate cumyl alcohol and polymer radicals, the polymer radicals are used to open the double bond on the cross-linked polyethylene precursor molecule and form carbon-carbon cross-linking bonds with the polymer chain, so as to obtain the modified cross-linked polyethylene, and carbon-carbon cross-linking bonds are also formed between two polymer radicals, so that the cross-linking reaction is completed.

[0012] Further, the weight ratio of the high-pressure polyethylene, the antioxidant 1010, the cross-linked polyethylene precursor and the dicumyl peroxide is 10:0.03:3:0.13.

[0013] Further, the preparation method of the cross-linked polyethylene precursor is as follows: 4,4'-dichlorobenzoyl, cuprous iodide, N,N-dimethyl-1,2-ethylenediamine and DMF are added into a three-necked flask under nitrogen protection and stirred, a condenser tube is connected, the temperature is increased to reflux, the maleimide solution is added, the reaction is carried out for 8-9 h, and the post-treatment is carried out, so as to obtain the cross-linked polyethylene precursor.

[0014] The synthesis mechanism of the cross-linked polyethylene precursor is as follows:

[0015]

[0016] Further, the use amount ratio of the 4,4'-dichlorobenzil, cuprous iodide, N,N-dimethyl-1,2-ethylenediamine and DMF is 28.11 g:0.95 g:1.76 g:500 mL, the molar ratio of 4,4'-dichlorobenzil to maleimide is 1:2, and the maleimide solution is composed of maleimide and DMF in a volume ratio of 1:1; the post-processing step is as follows: after the reaction is completed, the mixture is naturally cooled to room temperature, poured into deionized water, stirred until the solid is completely precipitated, filtered, the solid is washed with deionized water for 3-5 times, then washed with anhydrous ethanol for 1-2 times, and then the solid is placed in a vacuum drying oven at 40-60°C to dry to constant weight to obtain the crosslinked polyethylene precursor; the mass spectrometry data of the crosslinked polyethylene precursor is as follows: m / z: 400.0695 (100.0%), 401.0729 (23.8%), 402.0762 (2.7%), 402.0738 (1.2%).

[0017] Further, the modified plasticizer is prepared by the following steps:

[0018] A1, glycerol is added to a three-necked flask under nitrogen protection, the temperature is raised to 220-240°C, and maintained for 2 h, lead oxide and soybean oil are added to the three-necked flask, and the reaction is carried out for 6-8 h, and then the temperature is lowered to obtain soybean oil monoglyceride;

[0019] A2, the soybean oil monoglyceride and maleic anhydride are added to a three-necked flask under nitrogen protection, the temperature is raised to 80-90°C, n-butyl titanate and isooctanol are added, and maintained for 20-30 min until the reactants are completely melted, heated to reflux, and stirred for 6-10 h, and then the post-processing is carried out to obtain the modified plasticizer.

[0020] The synthesis mechanism of the modified plasticizer is as follows:

[0021] The activated glycerol acts as a nucleophile to attack the ester bond carbonyl carbon of the triglyceride in the soybean oil to form a tetrahedral intermediate, the tetrahedral intermediate is decomposed, one fatty acid chain of the original triglyceride is replaced by glycerol to generate fatty acid monoglyceride and fatty acid diglyceride, and the process can be repeated until the monoglyceride is generated; the maleic anhydride is initially reacted with the hydroxyl group of the soybean oil monoglyceride to open the anhydride ring to generate a half ester intermediate, under the catalysis of n-butyl titanate, the carboxyl group of the half ester intermediate continues to react with the hydroxyl group of other soybean oil monoglyceride to form an ester bond and release water molecules, which promotes chain growth, the monohydroxyl group of isooctanol reacts with the carboxyl group at the end of the polyester chain to form a stable ester bond, which prevents further chain growth, and the modified plasticizer is obtained.

[0022] Further, in step A1, the weight ratio of glycerol, lead oxide and soybean oil is 1 g:0.01 g:5.5 mL; in step A2, the weight ratio of soybean oil monoglyceride, maleic anhydride, tetrabutyl titanate and isooctanol is 3.0:10.7:0.171:1.3, and the post-treatment step is: after the reaction is completed, the reaction liquid is cooled to room temperature, a saturated sodium carbonate solution is added to adjust the pH to 7, ethyl acetate is added, stirred for 15-30 min, and then allowed to stand to separate the liquid, the organic phase is washed with deionized water three times, then dried with anhydrous magnesium sulfate for 4-6 h, filtered, and the filtrate is transferred to a rotary evaporator with a water bath temperature of 60-70℃, and the low boiling point substance is removed under reduced pressure to obtain the modified plasticizer.

[0023] Further, the filler aid is prepared by the following steps: 4,4'-diamino diphenyl ether, modified nano-titanium dioxide and N,N-dimethylacetamide are added to a three-necked flask, ultrasonic treatment is performed for 1-2 h, pyromellitic dianhydride is added and stirred for 4-6 h to obtain the filler aid.

[0024] The synthesis mechanism of the filler aid is as follows:

[0025]

[0026] In the formula, R represents a nanoparticle;

[0027] The amino group of 4,4-diamino diphenyl ether acts as a nucleophile to attack the anhydride carbonyl carbon of pyromellitic dianhydride, causing the anhydride ring to open to form a carboxylate intermediate, which obtains a proton from the solvent or another amine molecule to convert into a carboxylic acid, while the amino group loses a proton to form a stable amide bond with the carbonyl group. Each pyromellitic dianhydride molecule can react with the amino groups of two 4,4-diamino diphenyl ether molecules to form a linear polyamide acid main chain. The polar groups on the surface of the titanium dioxide interact with the end groups of the polyamide acid through hydrogen bonds or van der Waals forces, enhancing the interfacial bonding. Moreover, the long-chain organic groups on the surface of the titanium dioxide prevent agglomeration by forming steric hindrance between particles.

[0028] Further, the amount ratio of 4,4-diamino diphenyl ether, modified nano-titanium dioxide, N,N-dimethylacetamide and pyromellitic dianhydride is 4.5 g:0.45 g:100 mL:5 g.

[0029] Further, the preparation method of the modified nano-titanium dioxide is as follows: nano-titanium dioxide and KH-550 solution are added into a three-necked flask, ultrasonic treatment is carried out for 30-40 min, the reaction temperature is increased to 70-80 DEG C, and reaction is carried out for 6-7 h; after the reaction is completed, the reaction product is dried in a vacuum drying box at 50-60 DEG C until the weight is constant, thereby obtaining the modified nano-titanium dioxide; wherein the KH-550 solution is composed of gamma-aminopropyl triethoxysilane, ethanol and purified water in a ratio of 1g:95mL:5mL; and the ratio of the amount of nano-titanium dioxide to the amount of KH-550 solution is 1g:1mL.

[0030] The application further provides a preparation method of the soft high-pressure-resistant insulating wire material for automobiles.

[0031] S1, the modified cross-linked polyethylene, the modified plasticizer, the filler aid and the additive are added into a mixing machine and uniformly mixed to obtain a mixture;

[0032] S2, the mixture is added into a double-screw extruder, and melt extrusion is carried out to obtain the weather-resistant flame-retardant cable material.

[0033] The application has the following advantages:

[0034] 1, the application is through the reaction of the double bond of the modified cross-linked polyethylene and the amino group of the filler aid, the ester group of the modified plasticizer and the amino group on the surface of the filler to form a hydrogen bond, which reduces the interface defects and improves the mechanical properties; the polyimide segment and the cross-linked polyethylene network are interpenetrated; the long chain of the modified plasticizer is inserted into the gap between the polyethylene chains; the softness of the plasticizer and the rigidity of the polyimide are balanced, so that the material is resistant to bending and has mechanical strength; in the modified cross-linked polyethylene, the cuprous iodide catalytic system can realize efficient coupling of aryl chloride under mild conditions, which avoids high temperature and strong corrosion conditions in traditional reactions, reduces energy consumption and equipment requirements, and generates maleimide groups as active sites to provide active sites for subsequent cross-linking; the three-dimensional network structure formed by cross-linking limits the slip of molecular chains, significantly improves the tensile strength, impact resistance and heat distortion temperature of the material, expands the high-temperature application scenarios, and the conjugated system of the aromatic ring and the double bond of the maleimide has excellent antioxidant properties, which further prolongs the service life of the material; the carbonyl group and the benzoin structure in the cross-linked polyethylene precursor structure jointly play a role in the same molecule, which can inhibit space charge ability and capture high-energy electrons, so that the multifunctional cross-linked network can comprehensively improve the high-voltage insulation performance of the modified cross-linked polyethylene.

[0035] 2、The application is to modify the plasticizer, the long-chain alkyl of the modified plasticizer is inserted between the polyethylene molecular chain, the intermolecular van der Waals force is weakened, the glass transition temperature is reduced, the material is more easily melted and flowed during processing, the softness is kept after forming, the double bond introduced by maleic anhydride can participate in the crosslinking reaction of polyethylene, chemical covalent bond is formed, the volatilization and migration of the plasticizer at high temperature are reduced, the hardening and cracking of the cable insulation layer caused by the loss of the plasticizer is avoided, the crosslinking between the polyethylene molecular chains is promoted, the crosslinking network is more uniform, the mechanical strength and the voltage breakdown resistance are improved, and the service life is prolonged; the flexible segment of the plasticizer is interpenetrated with the crosslinking network of polyethylene, the tensile resistance and toughness of the material are improved while the insulation is kept, the mechanical stress during the laying of the cable is adapted, and the long-chain structure of the vegetable oil-based plasticizer is more similar to the polyethylene segment, the compatibility is better, and the plasticizer is not easy to migrate and separate out.

[0036] 3、The application is to modify the filler aid, the high specific surface area of nano-titanium dioxide forms an interpenetrating network with the polyimide segment, is combined with the polyethylene matrix through chemical bonds, limits the molecular chain movement, improves the tensile strength and elongation at break; the shielding effect of titanium dioxide on ultraviolet rays can inhibit the photo-oxidative aging of polyethylene, the aromatic ring structure of polyimide can also enhance the heat-oxidative aging resistance, and the nano filler can capture carriers, inhibit, improve the breakdown field strength, and improve the volume resistivity and electrical insulation; the flexible structure of the polyimide segment alleviates the difference in the thermal expansion coefficient between the nano filler and the polyethylene matrix, reduces the interface stress cracking, the hydrolysis of the silane coupling agent and the condensation of the titanium dioxide surface hydroxyl group, and the amino group at the other end forms a chemical bond with the polyethylene matrix, improving the interfacial compatibility of the filler and the matrix, reducing the interface gap and defects, and improving the corona resistance; the polar groups of the modified plasticizer form hydrogen bonds with the amide groups and anhydride groups of polyimide, and at the same time, the coupling agent treated on the surface of nano-titanium dioxide is combined, reducing the interfacial tension, promoting the uniform dispersion of the filler in the matrix, and the synergistic system of the three through the matrix skeleton-flexible adjustment-enhanced filling makes the modified crosslinked polyethylene wire material have the comprehensive properties of softness, high voltage resistance, high temperature resistance and long service life. DETAILED DESCRIPTION

[0037] The technical solutions of the application will be described clearly and completely in combination with the embodiments below, obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0038] In the application, the high-pressure polyethylene is from Shanghai Dingfen Chemical Technology Co., Ltd., the CAS number is 9002-88-4, and the melting point is 92℃;

[0039] In the application, glycerol is from Wuhan Jixin Yibang Biological Technology Co., Ltd., CAS No. 56-81-5, boiling point is 290℃;

[0040] In the application, soybean oil is from Shanghai Macklin Biochemical Technology Co., Ltd., item No. S817900-2.5L, reagent grade;

[0041] In the application, antioxidant 1010 is from Tianjin Li'anlong New Material Co., Ltd., CAS No. 6683-19-8, boiling point is 779.1℃;

[0042] In the application, KH-550 is γ-aminopropyl triethoxysilane, from Danyang City Organic Silicon Material Industry Co., Ltd., CAS No. 919-30-2, boiling point is 217℃.

[0043] Example 1

[0044] The embodiment provides a preparation method of a soft high-pressure-resistant insulating wire material for automobiles, comprising the following steps:

[0045] S1, preparing modified cross-linked polyethylene

[0046] Maleimide 300 mL and DMF 300 mL are mixed to obtain a maleimide solution, which is prepared;

[0047] Take 281 g of 4,4'-dichlorobenzoyl, 9.5 g of cuprous iodide, 17.5 g of N,N-dimethyl-1,2-ethylenediamine and 500 mL of DMF and add them to a three-necked flask under nitrogen protection, stir, raise the temperature to reflux, add 500 mL of maleimide solution, react for 8 h, after the reaction is completed, naturally cool to room temperature, pour the mixture into deionized water, stir until the solid completely precipitates, filter, wash the solid with deionized water for 3 times, then wash the solid with anhydrous ethanol for 2 times, and then dry the solid in a 40℃ vacuum drying oven until the weight is constant to obtain a cross-linked polyethylene precursor;

[0048] 100 g of high-pressure polyethylene is added to a rheometer, the temperature of the rheometer is set to 200℃, the rotation speed is 50 rpm, 0.3 g of antioxidant 1010 and 0.3 g of cross-linked polyethylene precursor are added in sequence, and mixing is performed for 3 min, the rheometer is set to 110℃, the rotation speed is 50 rpm, 1.3 g of dicumyl peroxide is added to the system, and mixing is performed for 2 min to obtain modified cross-linked polyethylene.

[0049] S2, preparing modified plasticizer

[0050] Take 184 g of glycerol and add it to a three-necked flask under nitrogen protection, raise the temperature to 220℃, keep for 2 h, add 1.84 g of lead oxide and 1 L of soybean oil to the three-necked flask, react for 6 h, and then cool to obtain soybean oil monoglyceride;

[0051] Weighing: soybean oil monoglyceride and maleic anhydride are added to a three-necked flask under nitrogen protection, the temperature is raised to 80℃, n-butyl titanate and isooctanol are added, and the reaction is kept for 20min until the reactants are completely melted, heated to reflux, and stirred for 6h, after the reaction is completed, the reaction liquid is cooled to room temperature, the pH is adjusted to 7 with saturated sodium carbonate solution, ethyl acetate is added, stirred for 15min, and then separated by standing, the organic phase is washed with deionized water three times, dried with anhydrous magnesium sulfate for 4h, filtered, and the filtrate is transferred to a rotary evaporator with a water bath temperature of 60℃, and the low boiling point substances are removed by evaporation under reduced pressure to obtain a modified plasticizer.

[0052] S3, preparation of filler aid

[0053] Mix 5g of γ-aminopropyl triethoxysilane, 475mL of ethanol and 25mL of purified water to obtain a KH-550 solution, ready for use;

[0054] Weighing: 100g of nano-titanium dioxide and 100mL of KH-550 solution are added to a three-necked flask, ultrasonic for 30min, the reaction temperature is raised to 70℃, and the reaction is kept for 6h, after the reaction is completed, it is placed in a 50℃ vacuum drying oven and dried to constant weight to obtain modified nano-titanium dioxide;

[0055] Weighing: 4,4'-diamino diphenyl ether 45g, modified nano-titanium dioxide 4.5g and N,N-dimethylacetamide 1000mL are added to a three-necked flask, ultrasonic for 1h, 50g of pyromellitic dianhydride is added and stirred for 4h to obtain a filler aid.

[0056] S4, preparation of weather-resistant flame-retardant cable material

[0057] Mix the modified crosslinked polyethylene 60 parts, modified plasticizer 8 parts, filler aid 15 parts, silicone master batch 0.75 parts, and stearoyl benzoyl methane 0.25 parts in a mixer to obtain a mixture;

[0058] The mixture is added to a twin-screw extruder, the feeding section temperature is set to 80℃, the screw rotation speed is 20rpm, the melting section temperature is 160℃, the screw rotation speed is 40rpm, the mixing section temperature is 170℃, and the shearing mixing speed is 30rpm, then melt extrusion to obtain a soft high-pressure resistant insulation wire material.

[0059] Example 2

[0060] The present embodiment provides a preparation method of a soft high-pressure resistant insulation wire material for automobiles, comprising the following steps:

[0061] S1, preparation of modified crosslinked polyethylene

[0062] Mix 300 mL of maleimide with 300 mL of DMF to obtain a maleimide solution, ready for use;

[0063] Weigh 281 g of 4,4'-dichlorobenzil, 9.5 g of cuprous iodide, 17.5 g of N,N-dimethyl-1,2-ethanediamine, and 500 mL of DMF into a nitrogen-protected three-neck flask, stir, connect a condenser tube, raise the temperature to reflux, add 500 mL of maleimide solution, react for 8.5 h, after the reaction is completed, naturally cool to room temperature, pour the mixture into deionized water, stir until the solid completely precipitates, filter, wash the solid with deionized water 4 times, then wash with anhydrous ethanol 2 times, and then dry the solid in a 50℃ vacuum drying oven to constant weight to obtain a crosslinked polyethylene precursor;

[0064] Add 100 g of high-pressure polyethylene to a rheometer, set the rheometer temperature to 250℃, and the rotation speed to 55 rpm, add 0.3 g of antioxidant 1010 and 0.3 g of crosslinked polyethylene precursor in turn, and mix for 4 min, set the rheometer to 115℃ and the rotation speed to 55 rpm, add 1.3 g of dicumyl peroxide to the system, and mix for 2.5 min to obtain modified crosslinked polyethylene.

[0065] S2, preparation of modified plasticizer

[0066] Weigh 184 g of glycerol into a nitrogen-protected three-neck flask, raise the temperature to 230℃, and maintain for 2 h, add 1.84 g of lead oxide and 1 L of soybean oil to the three-neck flask, and react for 6.5 h, then cool to obtain soybean oil monoglyceride;

[0067] Weigh soybean oil monoglyceride and maleic anhydride into a nitrogen-protected three-neck flask, raise the temperature to 85℃, add n-butyl titanate and isooctanol, maintain for 25 min until the reactants are completely melted, heat to reflux, stir for 8 h, after the reaction is completed, cool the reaction liquid to room temperature, adjust the pH to 7 with saturated sodium carbonate solution, add ethyl acetate, stir for 20 min, stand to separate the liquid, wash the organic phase with deionized water three times, then dry with anhydrous magnesium sulfate for 5 h, filter, transfer the filtrate to a rotary evaporator with a water bath temperature of 65℃, and evaporate the low-boiling substances under reduced pressure to obtain a modified plasticizer.

[0068] S3, preparation of filler aid

[0069] Mix 5 g of γ-aminopropyltriethoxysilane, 475 mL of ethanol, and 25 mL of purified water to obtain a KH-550 solution, ready for use;

[0070] Weighing: 100 g of nano-titanium dioxide and 100 mL of KH-550 solution are added to a three-necked flask, ultrasonic for 35 min, the reaction temperature is raised to 75℃, and the reaction is carried out for 6.5 h. After the reaction is completed, it is placed in a 55℃ vacuum drying box for drying to constant weight to obtain modified nano-titanium dioxide;

[0071] Weighing: 45 g of 4,4'-diamino diphenyl ether, 4.5 g of modified nano-titanium dioxide, and 1000 mL of N,N-dimethylacetamide are added to a three-necked flask, ultrasonic for 1.5 h, 50 g of pyromellitic dianhydride is added, and stirring is carried out for 4-6 h to obtain a filler aid.

[0072] S4, preparation of a weather-resistant flame-retardant cable material

[0073] The modified cross-linked polyethylene 70 parts, the modified plasticizer 10 parts, the filler aid 20 parts, the silicone master batch 1.5 parts, and the stearylbenzoyl methane 0.5 part are added to a mixer and uniformly mixed to obtain a mixed material.

[0074] The mixed material is added to a twin-screw extruder, the feeding section temperature is set to 90℃, the screw rotating speed is 25 rpm, the melting section temperature is 175℃, the screw rotating speed is 50 rpm, the mixing section temperature is 185℃, and the shearing mixing is 35 rpm. The soft high-pressure-resistant insulation wire material is obtained by melt extrusion.

[0075] Example 3

[0076] The embodiment provides a preparation method of a soft high-pressure-resistant insulation wire material for automobiles, which comprises the following steps:

[0077] S1, preparation of modified cross-linked polyethylene

[0078] The maleimide 300 mL is mixed with DMF 300 mL to obtain a maleimide solution, which is prepared for use;

[0079] Weighing: 279 g of 4,4'-dichlorobenzil, 9.5 g of cuprous iodide, 17.5 g of N,N-dimethyl-1,2-ethanediamine, and 500 mL of DMF are added to a three-necked flask under nitrogen protection, stirring, connecting a condenser tube, raising the temperature to reflux, adding 500 mL of maleimide solution, and reacting for 9 h. After the reaction is completed, it is naturally cooled to room temperature, the mixed liquid is poured into deionized water, stirring is carried out until the solid is completely precipitated, the solid is filtered, washed with deionized water for 5 times, washed with anhydrous ethanol for 2 times, and then the solid is placed in a 60℃ vacuum drying box for drying to constant weight to obtain a cross-linked polyethylene precursor.

[0080] 100g high pressure polyethylene was added into a rheometer, the temperature of the rheometer was set to 300℃, the rotation speed was 60rpm, 0.3g antioxidant 1010 and 0.3g crosslinked polyethylene precursor were added in turn, and mixing was carried out for 5min; the rheometer was set to 120℃, the rotation speed was 60rpm, 1.3g dicumyl peroxide was added into the system, and mixing was carried out for 3min to obtain modified crosslinked polyethylene.

[0081] S2, preparation of modified plasticizer

[0082] Weighing: 184g glycerol was added into a nitrogen-protected three-necked flask, the temperature was raised to 240℃ and maintained for 2h, 1.84g lead oxide and 1L soybean oil were added into the three-necked flask, and the reaction was carried out for 8h; after cooling, soybean oil monoglyceride was obtained;

[0083] Weighing: soybean oil monoglyceride and maleic anhydride were added into a nitrogen-protected three-necked flask, the temperature was raised to 90℃, n-butyl titanate and isooctanol were added, and the reaction was carried out for 30min until the reactants were completely melted; heating was carried out to reflux, and the reaction was carried out for 10h; after the reaction was completed, the reaction liquid was cooled to room temperature, the pH was adjusted to 7 with saturated sodium carbonate solution, ethyl acetate was added, stirring was carried out for 30min, and the reaction liquid was allowed to stand to separate; the organic phase was washed with deionized water for three times, dried with anhydrous magnesium sulfate for 6h, filtered, and the filtrate was transferred into a rotary evaporator with a water bath temperature of 70℃; low boiling point substances were removed by evaporation under reduced pressure to obtain a modified plasticizer.

[0084] S3, preparation of filler aid

[0085] Mixing 5g γ-aminopropyl triethoxysilane, 475mL ethanol and 25mL purified water to obtain a KH-550 solution, which was prepared for use;

[0086] Weighing: 100g nanometer titanium dioxide and 100mL KH-550 solution were added into a three-necked flask, and ultrasonic treatment was carried out for 40min; the reaction temperature was raised to 80℃, and the reaction was carried out for 7h; after the reaction was completed, the reaction liquid was placed in a 60℃ vacuum drying oven for drying until the weight was constant to obtain modified nanometer titanium dioxide.

[0087] Weighing: 4,4′-diamino diphenyl ether 45g, modified nanometer titanium dioxide 4.5g and N,N-dimethylacetamide 1000mL were added into a three-necked flask, and ultrasonic treatment was carried out for 2h; 50g pyromellitic dianhydride was added and stirring was carried out for 6h to obtain a filler aid.

[0088] S4, preparation of weather-resistant flame-retardant cable material

[0089] Modified crosslinked polyethylene 80 parts, modified plasticizer 12 parts, filler aid 25 parts, silicone master batch 2.25 parts and stearoylbenzoylmethane 0.75 part were added into a mixer and uniformly mixed to obtain a mixture.

[0090] The mixture is added into a twin-screw extruder, the feeding section temperature is set to 100℃, the screw rotation speed is 30rpm, the melting section temperature is 190℃, the screw rotation speed is 60rpm, the mixing section temperature is 200℃, the shearing mixing is 40rpm, and the melt extrusion obtains the soft high-pressure resistant insulation wire material.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 3 is that step S1 is cancelled, and polyethylene is used to replace the modified crosslinked polyethylene.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 3 is that step S2 is cancelled, and epoxy soybean oil is used to replace the modified plasticizer.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 3 is that step S3 is cancelled, and nano titanium dioxide is used to replace the filler aid.

[0097] Performance test:

[0098] The volume resistivity, heat shock resistance and dielectric strength of the weather-resistant flame-retardant cable material prepared in Examples 1-3 and Comparative Examples 1-3 are determined according to the standard GB / T 32129-2015 "Halogen-free low-smoke flame-retardant cable material for wire and cable"; wherein the heat shock resistance test temperature is 130±3℃, and the time is 1h;

[0099] The tensile strength and elongation at break of the weather-resistant flame-retardant cable material prepared in Examples 1-3 and Comparative Examples 1-3 are determined according to the standard GB / T 1040.3-2006 "Determination of tensile properties of plastics-Part 3: test conditions for films and sheets";

[0100] The heat distortion performance of the weather-resistant flame-retardant cable material prepared in Examples 1-3 and Comparative Examples 1-3 is determined according to the standard GB / T 8815-2008 "Soft polyvinyl chloride plastic for wire and cable", and the heat distortion test temperature is 120±2℃, and the specific test results are shown in Table 1 below:

[0101] Table 1-Performance test data table of the sample

[0102]

[0103]

[0104] Data analysis:

[0105] Comparative analysis of the data in Table 1, the tensile strength of the soft high-voltage insulation wire material prepared by the application reaches 36 MPa, the elongation at break reaches 556%, the volume resistivity reaches 1*10 16 Ω·cm, the heat shock resistance is not cracking, the dielectric strength reaches 35 kV·mm -1 , the heat distortion reaches 4%, which shows that the application combines the insulation of modified cross-linked polyethylene with the high heat resistance of polyimide, balances the softness of the plasticizer with the rigidity of polyimide, and improves the mechanical properties and high-voltage insulation performance of the material.

[0106] Compared with the example, the carbonyl and benzoin structure in the cross-linked polyethylene precursor structure plays a role together in the same molecule, which can inhibit the space charge ability and capture high-energy electrons, so that the multifunctional cross-linked network can comprehensively improve the high-voltage insulation performance of the modified cross-linked polyethylene.

[0107] Compared with the example, the flexible segment of the plasticizer and the cross-linked polyethylene network interpenetrate, which improves the tensile capacity and toughness of the material while maintaining the insulation, and adapts to the mechanical stress during cable laying.

[0108] Compared with the example, the flexible structure of the polyimide segment relieves the difference in the thermal expansion coefficient between the nano filler and the polyethylene matrix, reduces the interface stress cracking, the silane coupling agent hydrolysis and the titanium dioxide surface hydroxyl condensation, and the amino group at the other end forms a chemical bond with the polyethylene matrix, which improves the interface compatibility of the filler and the matrix, reduces the interface void and defects, and improves the corona resistance.

[0109] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments. Obviously, many modifications and changes can be made according to the content of the specification. The embodiments are selected and described in detail in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited by the claims and their entire scope and equivalents.

Claims

1. A soft high-voltage insulating wire material for automobiles, characterized in that: The soft high-voltage resistant insulated wire material comprises the following components in parts by weight: 60-80 parts of modified cross-linked polyethylene, 8-12 parts of modified plasticizer, 15-25 parts of filler additive, and 1-3 parts of additive, wherein the additive is composed of silicone masterbatch and stearyl benzoyl methane in a weight ratio of 3:1; The preparation method of the modified cross-linked polyethylene comprises: adding high-pressure polyethylene to a rheometer, setting the temperature of the rheometer to 200-300° C. and the rotation speed to 50-60 rpm, sequentially adding an antioxidant 1010 and a cross-linked polyethylene precursor, mixing for 3-5 minutes, setting the rheometer to 110-120° C. and the rotation speed to 50-60 rpm, adding dicumyl peroxide to the system, and mixing for 2-3 minutes to obtain the modified cross-linked polyethylene.

2. The soft high-voltage insulating wire material for automobiles according to claim 1, characterized in that: The weight ratio is 10:0.03:3:0.

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3. The soft high-voltage insulating wire material for automobiles according to claim 1, characterized in that: The preparation method of the cross-linked polyethylene precursor comprises the following steps: adding 4,4′-dichlorobenzil, cuprous iodide, N,N-dimethyl-1,2-ethylenediamine and DMF into a nitrogen-protected three-necked flask and stirring, raising the temperature to reflux, adding a maleimide solution, reacting for 8-9 hours, and post-treating to obtain the cross-linked polyethylene precursor.

4. The soft high-voltage insulating wire material for automobiles according to claim 3, characterized in that: The amount ratio of the 4,4′-dichlorobenzil, cuprous iodide, N,N-dimethyl-1,2-ethylenediamine and DMF is 28.11 g:0.95 g:1.76 g:500 mL, the molar ratio of 4,4′-dichlorobenzil to maleimide is 1:2, and the maleimide solution is composed of maleimide and DMF in a volume ratio of 1:1; the post-treatment step is: after the reaction is completed, naturally cooling to room temperature, pouring the mixed solution into deionized water, stirring until the solid is completely precipitated, filtering, washing the solid with deionized water 3-5 times, then washing with anhydrous ethanol 1-2 times, and then placing the solid in a vacuum drying oven at 40-60°C to dry to constant weight to obtain a cross-linked polyethylene precursor.

5. The soft high-voltage insulating wire material for automobiles according to claim 1, characterized in that: The preparation of the modified plasticizer is obtained by the following steps: A1. Add glycerol to a nitrogen-protected three-necked flask, raise the temperature to 220-240°C, and maintain for 2 hours. Then add lead oxide and soybean oil to the three-necked flask, react for 6-8 hours, and then cool to obtain soybean oil monoglyceride. A2. Add soybean oil monoglyceride and maleic anhydride to a three-necked flask protected by nitrogen, raise the temperature to 80-90°C, add n-butyl titanate and isooctyl alcohol, maintain for 20-30 minutes until the reactants are completely melted, heat to reflux, stir and react for 6-10 hours, and post-treat to obtain a modified plasticizer.

6. The soft high-voltage insulating wire material for automobiles according to claim 1, characterized in that: In step A1, the amount ratio of glycerol, lead oxide and soybean oil is 1g:0.01g:5.5mL; in step A2, the weight ratio of soybean oil monoglyceride, maleic anhydride, tetrabutyl titanate and isooctyl alcohol is 3.0:10.7:0.171:1.

3. The post-processing step is as follows: after the reaction is completed, the reaction solution is cooled to room temperature, the pH is adjusted to 7 with saturated sodium carbonate solution, ethyl acetate is added, stirred for 15-30 minutes, and allowed to stand for separation. The organic phase is washed three times with deionized water, dried with anhydrous magnesium sulfate for 4-6 hours, filtered, and the filtrate is transferred to a rotary evaporator with a water bath temperature of 60-70°C, and low-boiling substances are evaporated under reduced pressure to obtain a modified plasticizer.

7. The soft high-voltage insulating wire material for automobiles according to claim 1, characterized in that: The filler auxiliary agent is prepared by the following steps: adding 4,4'-diaminodiphenyl ether, modified nano titanium dioxide and N,N-dimethylacetamide into a three-necked flask, ultrasonicating for 1-2 hours, adding pyromellitic dianhydride and stirring for 4-6 hours to obtain the filler auxiliary agent.

8. The soft high-voltage insulating wire material for automobiles according to claim 7, characterized in that: The usage ratio of the 4,4′-diaminodiphenyl ether, the modified nano-titanium dioxide, the N,N-dimethylacetamide and the pyromellitic dianhydride is 4.5 g:0.45 g:100 mL:5 g.

9. The soft high-voltage insulating wire material for automobiles according to claim 7, characterized in that: The modified nano-titanium dioxide preparation method comprises the following steps: adding nano-titanium dioxide and a KH-550 solution into a three-necked flask, ultrasonicating for 30-40 minutes, raising the reaction temperature to 70-80° C., reacting for 6-7 hours, and drying in a vacuum drying oven at 50-60° C. to a constant weight after the reaction to obtain the modified nano-titanium dioxide, wherein the KH-550 solution comprises γ-aminopropyltriethoxysilane, ethanol, and purified water in a ratio of 1 g:95 mL:5 mL; and the usage ratio of the nano-titanium dioxide to the KH-550 solution is 1 g:1 mL.

10. The method for preparing a soft high-voltage resistant insulated wire material for automobiles according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, adding modified cross-linked polyethylene, modified plasticizer, filler additives and additives into a mixer and mixing them evenly to obtain a mixture; S2. Add the mixed material into a twin-screw extruder to melt and extrude the soft high-voltage resistant insulating wire material.

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