Polyurea coating for repairing cable sheath and preparation method thereof

Abstract

The invention discloses a polyurea coating for repairing a cable sheath and a preparation method of the polyurea coating, and belongs to the technical field of polyurea coatings. Comprising the following raw materials in parts by weight: 6 to 10 parts of acetone, 20 to 30 parts of isophorone diisocyanate, 3 to 6 parts of dimethylolpropionic acid, 0.2 to 0.4 part of dibutyltin dilaurate, 30 to 40 parts of polyether amine, 2 to 4 parts of triethylamine, 5 to 15 parts of a modified filler, 100 to 200 parts of water and 3 to 5 parts of a defoaming agent. The modified filler can enhance the mechanical strength and wear resistance of the coating, and effective utilization of waste resources is also realized; wherein the modifier can also enhance the oxidation resistance and a certain degree of waterproofness of the polyurea coating, and the polyurea coating has long-term and stable performance and is not easy to fall off; therefore, the prepared polyurea coating is a water-based coating, is environment-friendly, has excellent weather resistance, water resistance, wear resistance and mechanical strength, has stable and efficient oxidation resistance, and has important application value in the technical field of polyurea coatings.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurea coatings, and in particular relates to a polyurea coating for repairing cable sheaths and a preparation method thereof. Background Art

[0002] Cables are carriers for transmitting electrical signals and currents. The stability of their power supply will directly determine the operational safety of the equipment. At the same time, with the development of electric energy, the application of electrical equipment is becoming more and more popular, and the requirements for cable performance are becoming higher and higher. Conventional cables are composed of conductors, insulation layers and sheath layers, and the sheath is the outermost layer of the cable, providing mechanical protection and additional environmental protection. Because it is in direct contact with the external environment, the cable sheath is often partially damaged, cracked, and powdered during use, making the cable unusable. In order to better protect and repair the cable, a repair coating can be applied to the cable sheath to repair and protect the cable, so as to improve the durability of the cable sheath and reduce economic losses.

[0003] Polyurea is an elastomeric substance generated by the reaction of isocyanate components and amino compound components. It is divided into pure polyurea and semi-polyurea, and their properties are different. The most basic characteristics of polyurea are anti-corrosion, waterproof, and wear resistance. In addition, polyurea coating is a high-performance environmentally friendly material with a fast curing speed. Using it for cable sheath can greatly improve the performance of the cable sheath, making the cable sheath more corrosion-resistant, wear-resistant and waterproof. At present, the most commonly used polyurea is aromatic polyurea, but because aromatic polyurea also exposes some fatal shortcomings in application, such as easy yellowing and poor adhesion, it must be constructed with special equipment and inconvenient construction, which greatly limits its application and promotion. Not only that, with the continuous improvement of the demand for cable sheath performance, the waterproof performance of polyurea coating also needs to be further enhanced.

[0004] To prepare high-performance polyurea coatings, polyurea coatings need to have strong mechanical properties, and fillers are usually added to enhance the mechanical strength of polyurea coatings. With the rapid development of the automobile industry, the issue of waste automobile tires has received increasing attention. Waste tires are composed of cross-linked thermosetting polymer materials, which may take hundreds of years to decompose naturally. Using rubber powder produced by recycling waste tires as fillers not only greatly enhances the mechanical strength of polyurea coatings, but also realizes the effective utilization of waste resources. However, the compatibility of rubber powder with polyurea coatings is poor and needs to be improved. Therefore, it is urgent to solve the above problems to meet the higher demands in the field of polyurea coating technology. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a polyurea coating for repairing cable sheath and a preparation method thereof.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A method for preparing a polyurea coating for repairing a cable sheath comprises the following steps: Acetone, isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA) and dibutyltin dilaurate are mixed, stirred in a water bath under nitrogen protection, polyetheramine is added, and after stirring at room temperature, triethylamine (TEA) is added for neutralization reaction. Finally, modified filler, water and defoaming agent are added, stirred to obtain a polyurea coating for cable sheath repair.

[0007] Furthermore, the raw materials are calculated in parts by weight as follows: 6-10 parts of acetone, 20-30 parts of isophorone diisocyanate, 3-6 parts of dimethylolpropionic acid, 0.2-0.4 parts of dibutyltin dilaurate, 30-40 parts of polyetheramine, 2-4 parts of triethylamine, 5-15 parts of modified filler, 100-200 parts of water, and 3-5 parts of defoaming agent.

[0008] Furthermore, the defoaming agent is a silicone defoaming agent.

[0009] The isocyanate selected is isophorone diisocyanate, which is an alicyclic isocyanate, giving the coating excellent weather resistance. The resulting coating is a water-based coating with a low VOC content and is environmentally friendly.

[0010] Furthermore, the modified filler is prepared by the following steps: A1. Mix the tire recycled rubber powder with deionized water to make the rubber powder fully swell, filter to remove excess water, add urea and formaldehyde and stir, continue to swell, then add sodium dodecyl sulfate and deionized water and stir evenly, use triethanolamine to adjust the pH to 8-9, heat in a water bath and stir to react, finally use hydrochloric acid solution to adjust the pH to 2-3, continue to react, and after the reaction is completed, reduce pressure and filter, wash with deionized water and ethanol in turn to obtain pre-modified rubber powder; A2. Mix the pre-modified rubber powder obtained in step A1 with N,N-dimethylformamide (DMF), slowly add the modifier and deionized water in sequence, adjust the pH to 8-9 with aqueous ammonia, stir at room temperature, let stand for aging, and after aging, filter under reduced pressure, wash with ethanol and deionized water in sequence, and dry to obtain a modified filler.

[0011] Furthermore, in step A1, the ratio of the amount of tire recycled rubber powder, deionized water, urea, formaldehyde, and sodium dodecyl sulfate is 2g:100mL:4g:6g:0.05g.

[0012] Furthermore, in step A2, the ratio of N,N-dimethylformamide, modifier and deionized water is 50 mL:6 g:30 mL.

[0013] By swelling the recycled tire rubber powder in water to increase the free space, urea and formaldehyde small molecules can better penetrate into the recycled tire rubber powder particles, urea and formaldehyde undergo condensation polymerization reaction to generate urea-formaldehyde resin with a cross-linked network structure, and the cross-linked urea-formaldehyde molecular chains and rubber molecular chains are entangled with each other to form a urea-formaldehyde resin coating layer on the surface of the rubber powder, thereby achieving urea-formaldehyde pre-modification of the rubber powder. Using it as a filler can greatly enhance the tensile properties and wear resistance of the coating, and realize the effective utilization of waste tires.

[0014] Furthermore, the modifier is prepared by the following steps: S1. In a three-necked flask equipped with a thermometer, an electromagnetic stirrer and a spherical condenser, a drying tube is added to the outlet of the condenser, and the drying tube is connected to a tail gas absorption device to absorb the generated hydrogen chloride gas. After pentaerythritol and benzene are mixed, phosphorus trichloride is slowly added dropwise under stirring, and the temperature is controlled not to exceed 30° C. After the addition is completed, the temperature is raised to 70° C. and the reaction is carried out for 4 hours. After the reaction is completed, the solvent benzene and excess phosphorus trichloride are distilled off to obtain dichloropentaerythritol phosphite; the ratio of pentaerythritol, benzene and phosphorus trichloride is 13.6 g:100 mL:28.1 g; Pentaerythritol reacts with phosphorus trichloride to obtain dichloropentaerythritol phosphite; the specific reaction is as follows:

[0015] S2. In a three-necked flask equipped with a stirring device, dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate and N,N-dimethylformamide were mixed and stirred evenly, the reaction temperature was controlled to 75°C, and the reaction was kept warm for 5 hours. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by rotary evaporation. The mixture was then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate in a volume ratio of 4:3), and the eluent was removed by rotary evaporation to obtain intermediate 1; the ratio of dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate and N,N-dimethylformamide was 27.2 g:23.6 g:13.8 g:100 mL; Potassium carbonate is used as an acid-binding agent to catalyze the reaction, dichloropentaerythritol phosphite and 3,5-di-tert-butyl-4-hydroxybenzyl alcohol react, and by controlling the molar ratio of the two to be close to 1:1 and the dichloropentaerythritol phosphite to be slightly excessive, only one chlorine group on the dichloropentaerythritol phosphite participates in the reaction, and intermediate 1 is obtained; the specific reaction process is shown below:

[0016] S3. At room temperature, in a three-necked flask equipped with a stirring device, mix the intermediate 1, N,N-dimethylformamide and potassium carbonate (catalyst) evenly, then add 3-aminopropyltriethoxysilane dropwise, and control the temperature not to exceed 25°C during the addition. After the addition is completed, react at 60°C for 4 hours. After the reaction is completed, distill under reduced pressure, filter, wash with anhydrous ethanol 3-4 times, and dry in vacuo to obtain intermediate 2; the ratio of the amount of intermediate 1, N,N-dimethylformamide, potassium carbonate, and 3-aminopropyltriethoxysilane is 46.4g:150mL:13.8g:22.1g; Potassium carbonate is used as an acid-binding agent to catalyze the reaction, and intermediate 1 undergoes a nucleophilic substitution reaction with 3-aminopropyltriethoxysilane to obtain intermediate 2. The specific reaction process is as follows:

[0017] S4. At room temperature, in a three-necked flask equipped with a stirring device, under nitrogen protection, mix the intermediate 2 and N,N-dimethylformamide, turn on the stirrer, add dibutyltin oxide (catalyst), potassium carbonate and epichlorohydrin in sequence, slowly raise the temperature to 65°C, keep the reaction for 6 hours, and after the reaction is completed, distill under reduced pressure, and then purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 5:3), remove the eluent by rotary evaporation, and obtain a modifier; the ratio of the amount of intermediate 2, N,N-dimethylformamide, dibutyltin oxide, potassium carbonate, and epichlorohydrin is 64.9g:150mL:0.3g:13.8g:9.2g; Under the catalysis of dibutyltin oxide, intermediate 2 and epichlorohydrin undergo nucleophilic substitution, and potassium carbonate removes the hydrogen chloride generated by the reaction to obtain a modifier; the specific reaction is shown below:

[0018] The Si-O bond length in the silanol group at one end of the prepared modifier molecule is relatively long, so that the three hydrogens on the two non-polar methyl groups are like an open umbrella, which makes it very hydrophobic and can enhance the water resistance of the matrix; in addition, the silanol group can react with the abundant hydroxyl groups on the pre-modified rubber powder to graft the modifier on the rubber powder, thereby improving the interfacial effect of the rubber powder, improving the compatibility of the rubber powder with the polyurea matrix, giving full play to the performance of the modified filler, and greatly enhancing the wear resistance and mechanical strength of the matrix; not only that, the modifier is grafted on the rubber powder, making it difficult for the modifier to migrate and fall off, thereby improving the long-term stability of the modifier's performance; in addition, the modifier molecule also contains phosphite, hindered phenol and epoxy structures, among which phosphite can be used as a type of auxiliary antioxidant to Decompose the hydroperoxides generated in the polymer due to oxidative aging and make them inactive substances, thereby achieving the purpose of terminating or delaying the oxidative degradation of the polymer. The hindered phenol group belongs to phenolic antioxidants. The structure of this type of antioxidant contains -OH functional groups, which are more likely to provide H atoms in the reaction. This process occurs through proton donation, thereby destroying the auto-oxidation of free radicals in the chain reaction and achieving an antioxidant effect. It can play a synergistic role with phosphites to greatly enhance the antioxidant properties of the matrix. The modifier acts as an antioxidant in the production process to avoid adding additional antioxidants and affecting the homogeneity of the matrix. Finally, the introduced epoxy group can produce chemical bonding with the polyurea matrix to further improve the interfacial compatibility between the rubber powder and the polyurea matrix.

[0019] Therefore, the additive of the present invention can be further dispersed and stably present in the polyurea repair coating, is not easy to migrate and fall out, and fully exerts the flame retardant, UV resistance and hydrophobic effects. This chemical action can also further improve the dispersibility of the filler, thereby further improving the wear resistance of the coating to protect the cable sheath and make it less likely to be damaged and cracked.

[0020] Beneficial effects of the present invention: 1. The polyurea coating prepared by the present invention is a water-based coating with low VOC content and is environmentally friendly. In addition, isophorone diisocyanate is selected as a raw material, which gives the coating excellent weather resistance; 2. By pre-modifying and modifying the recycled tire rubber powder, not only the compatibility of rubber powder with polyurea coating is improved, the performance of rubber powder is fully exerted, the mechanical strength and wear resistance of the coating are enhanced, but also the effective utilization of waste resources is achieved; 3. The prepared modifier can modify the pre-modified rubber powder, further enhance the compatibility of the rubber powder with the polyurea coating, and enhance the anti-oxidation and waterproof properties of the polyurea coating to a certain extent, and the performance is long-lasting and not easy to fall off; Therefore, the polyurea coating prepared by the present invention is an environmentally friendly water-based coating, and has excellent weather resistance, water resistance, wear resistance and mechanical strength, and has stable and efficient antioxidant properties. When used for cable sheaths, it can effectively protect the cable sheaths, improve their water resistance, corrosion resistance and durability, and has important application value in the field of polyurea coating technology. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] Preparation of modifier: S1. In a three-necked flask equipped with a thermometer, an electromagnetic stirrer and a spherical condenser, a drying tube is added to the outlet of the condenser, and the drying tube is connected to a tail gas absorption device to absorb the generated hydrogen chloride gas. After mixing 13.6 g of pentaerythritol and 100 mL of benzene, 28.1 g of phosphorus trichloride is slowly added dropwise under stirring, and the temperature is controlled not to exceed 30° C. After the addition is completed, the temperature is raised to 70° C. and the reaction is carried out for 4 hours. After the reaction is completed, the solvent benzene and excess phosphorus trichloride are removed by distillation to obtain dichloropentaerythritol phosphite; S2. In a three-necked flask equipped with a stirring device, 27.2 g of dichloropentaerythritol phosphite, 23.6 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 13.8 g of potassium carbonate and 100 mL of N,N-dimethylformamide were mixed and stirred uniformly, the reaction temperature was controlled to 75° C., and the reaction was kept warm for 5 hours. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by rotary evaporation. The mixture was then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate in a volume ratio of 4:3), and the eluent was removed by rotary evaporation to obtain intermediate 1. S3. At room temperature and under nitrogen protection, in a three-necked flask equipped with a stirring device, 46.4 g of intermediate 1, 150 mL of N,N-dimethylformamide and 13.8 g of potassium carbonate were mixed evenly, and 22.1 g of 3-aminopropyltriethoxysilane was added dropwise, and the temperature was controlled not to exceed 25°C during the addition. After the addition was completed, the reaction was carried out at 60°C for 4 hours. After the reaction was completed, the reaction was distilled under reduced pressure, filtered, washed with anhydrous ethanol 3 times, and dried in vacuo to obtain intermediate 2; S4. At room temperature and under nitrogen protection, in a three-necked flask equipped with a stirring device, mix 64.9 g of intermediate 2 and 150 mL of N,N-dimethylformamide, turn on the stirrer, add 0.3 g of dibutyltin oxide, 13.8 g of potassium carbonate and 9.2 g of epichlorohydrin in sequence, slowly raise the temperature to 65°C, keep the reaction for 6 hours, and after the reaction is completed, distill under reduced pressure, and then purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 5:3), and remove the eluent by rotary evaporation to obtain a modifier.

[0024] Example 2

[0025] Preparation of modifier: S1. In a three-necked flask equipped with a thermometer, an electromagnetic stirrer and a spherical condenser, a drying tube is added to the outlet of the condenser, and the drying tube is connected to a tail gas absorption device to absorb the generated hydrogen chloride gas. After mixing 27.2 g of pentaerythritol and 200 mL of benzene, 56.2 g of phosphorus trichloride is slowly added dropwise under stirring, and the temperature is controlled not to exceed 30° C. After the addition is completed, the temperature is raised to 70° C. and the reaction is carried out for 4 hours. After the reaction is completed, the solvent benzene and excess phosphorus trichloride are removed by distillation to obtain dichloropentaerythritol phosphite; S2. In a three-necked flask equipped with a stirring device, 54.4 g of dichloropentaerythritol phosphite, 47.2 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 27.6 g of potassium carbonate and 200 mL of N,N-dimethylformamide were mixed and stirred evenly, the reaction temperature was controlled to 75° C., and the reaction was kept warm for 5 hours. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by rotary evaporation. The mixture was then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate in a volume ratio of 4:3), and the eluent was removed by rotary evaporation to obtain intermediate 1; S3. At room temperature, in a three-necked flask equipped with a stirring device, 92.8 g of intermediate 1, 300 mL of N,N-dimethylformamide and 27.6 g of potassium carbonate were mixed evenly, and 44.2 g of 3-aminopropyltriethoxysilane was added dropwise, and the temperature was controlled not to exceed 25°C during the addition. After the addition was completed, the reaction was carried out at 60°C for 4 hours. After the reaction was completed, the reaction was distilled under reduced pressure, filtered, washed with anhydrous ethanol 3 times, and dried in vacuo to obtain intermediate 2; S4. At room temperature, under nitrogen protection, in a three-necked flask equipped with a stirring device, mix 129.8 g of intermediate 2 and 300 mL of N,N-dimethylformamide, turn on the stirrer, add 0.6 g of dibutyltin oxide, 27.6 g of potassium carbonate and 18.4 g of epichlorohydrin in sequence, slowly raise the temperature to 65°C, keep the reaction for 6 hours, and after the reaction is completed, distill under reduced pressure, and then purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 5:3), and remove the eluent by rotary evaporation to obtain a modifier.

[0026] Example 3

[0027] Preparation of modified fillers: A1. Mix 2g of tire recycled rubber powder with 80mL of deionized water, stir at 500rpm for 7 days to make the rubber powder fully swell, filter to remove excess water, add 4g of urea and 6g of formaldehyde, stir at 300rpm, continue swelling for 3 days, then add 0.05g of sodium dodecyl sulfate and 20mL of deionized water and stir evenly, use triethanolamine to adjust pH=8, heat in a water bath at 60℃, stir at 200rpm for 3h, finally adjust pH=2 with hydrochloric acid solution (mass fraction 12%), continue to react for 3h, filter the product under reduced pressure, and wash with deionized water and ethanol in turn to obtain pre-modified rubber powder; A2. The pre-modified rubber powder obtained in step A1 was mixed with 50 mL of N,N-dimethylformamide, and 6 g of the modifier obtained in Example 1 and 30 mL of deionized water were slowly added in sequence, and the pH was adjusted to 8 with aqueous ammonia. The mixture was stirred at 200 rpm for 4 h at room temperature, and allowed to stand for 8 h. Finally, the product was filtered under reduced pressure, washed with ethanol and deionized water in sequence, and dried to obtain a modified filler.

[0028] Example 4

[0029] Preparation of modified fillers: A1. Mix 4g of tire recycled rubber powder with 160mL of deionized water, stir at 500rpm for 7 days to make the rubber powder fully swell, filter to remove excess water, add 8g of urea and 12g of formaldehyde, stir at 300rpm, continue swelling for 3 days, then add 0.1g of sodium dodecyl sulfate and 40mL of deionized water and stir evenly, use triethanolamine to adjust pH=9, heat in a water bath at 60℃, stir at 200rpm for 3h, finally adjust pH=3 with hydrochloric acid solution (mass fraction 12%), continue to react for 3h, after the reaction is completed, reduce pressure and filter, wash with deionized water and ethanol in turn, to obtain pre-modified rubber powder; A2. Mix the pre-modified rubber powder obtained in step A1 with 100 mL of N,N-dimethylformamide, slowly add 12 g of the modifier obtained in Example 2 and 60 mL of deionized water in sequence, adjust the pH to 9 with aqueous ammonia, stir at 200 rpm for 4 h at room temperature, let stand for 8 h, and after aging, filter under reduced pressure, wash with ethanol and deionized water in sequence, and dry to obtain a modified filler.

[0030] Example 5

[0031] 6 g of acetone, 20 g of isophorone diisocyanate, 3 g of dimethylolpropionic acid and 0.2 g of dibutyltin dilaurate were mixed, stirred in a water bath at 40°C under nitrogen protection for 3 h, 30 g of polyetheramine was added, stirred at room temperature for 40 min, 2 g of triethylamine was added for neutralization reaction for 30 min, and finally 5 g of the modified filler prepared in Example 3, 100 g of water and 3 g of silicone defoamer (BYK-024) were added, and stirred at 1500 rpm for 30 min using a high-speed disperser to obtain a polyurea coating for cable sheath repair.

[0032] Example 6

[0033] 8 g of acetone, 25 g of isophorone diisocyanate, 4 g of dimethylolpropionic acid and 0.3 g of dibutyltin dilaurate were mixed, stirred in a 45°C water bath under nitrogen protection for 4 h, 35 g of polyetheramine was added, stirred at room temperature for 40 min, 3 g of triethylamine was added for neutralization reaction for 30 min, and finally 10 g of the modified filler prepared in Example 4, 150 g of water and 4 g of silicone defoamer (BYK-024) were added, and stirred at 1500 rpm for 30 min using a high-speed disperser to obtain a polyurea coating for cable sheath repair.

[0034] Example 7

[0035] 10 g of acetone, 30 g of isophorone diisocyanate, 6 g of dimethylolpropionic acid and 0.4 g of dibutyltin dilaurate were mixed, stirred in a 50°C water bath under nitrogen protection for 5 h, 40 g of polyetheramine was added, stirred at room temperature for 40 min, 4 g of triethylamine was added for neutralization reaction for 30 min, and finally 15 g of the modified filler prepared in Example 4, 200 g of water and 5 g of silicone defoamer (BYK-024) were added, and stirred at 1500 rpm for 30 min using a high-speed disperser to obtain a polyurea coating for cable sheath repair.

[0036] Comparative Example 1 Unmodified tire recycled rubber powder of equal mass was used to replace the modified filler in Example 7, and the remaining steps were the same as those in Example 7 to prepare a polyurea coating.

[0037] Comparative Example 2 Use commercially available waterproof and anti-corrosion polyurea coating.

[0038] The following performance tests were performed on Examples 5-7 and Comparative Examples 1-2 according to different test standards: The national standard GB / T 23446-2009 "Spray polyurea waterproof coating" is used to measure tensile strength, waterproofness and abrasion resistance; The national standard GB / T 1865 "Artificial weathering and artificial radiation exposure (filtered xenon arc radiation) of paints and varnishes" is used to determine the aging resistance, and the aging resistance is rated according to the GB / T 1766 standard; The national standard GB / T 1763-79 "Determination of chemical resistance of paint film" is used to determine the acid and alkali resistance of the coating film; The measured results are shown in the following table:

[0039] It can be seen from the above table that the polyurea coating prepared in the embodiment of the present invention has higher aging resistance, water resistance, wear resistance and mechanical strength than the control example, and has excellent corrosion resistance, and has important application value in the field of polyurea coating technology.

[0040] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A polyurea coating for cable sheath repair, characterized in that: The invention comprises the following raw materials in parts by weight: 6-10 parts of acetone, 20-30 parts of isophorone diisocyanate, 3-6 parts of dimethylol propionic acid, 0.2-0.4 parts of dibutyltin dilaurate, 30-40 parts of polyetheramine, 2-4 parts of triethylamine, 5-15 parts of modified filler, 100-200 parts of water, and 3-5 parts of defoamer; Wherein, the modified filler is prepared by the following steps: A1. Mix tire recycled rubber powder with deionized water, stir to fully swell the rubber powder, filter, add urea and formaldehyde, stir, continue swelling, then add sodium dodecyl sulfate and deionized water and stir evenly, add triethanolamine to adjust pH=8-9, heat in a water bath and stir, adjust pH=2-3 with hydrochloric acid solution, continue reaction, filter under reduced pressure, wash, and obtain pre-modified rubber powder; A2. Mix the pre-modified rubber powder obtained in step A1 with N,N-dimethylformamide, slowly add the modifier and deionized water in sequence, adjust the pH to 8-9 with aqueous ammonia, stir, stand for aging, filter under reduced pressure, wash, and dry to obtain a modified filler.

2. The polyurea coating for cable sheath repair according to claim 1, characterized in that: The modifier is prepared by the following steps: S1. After pentaerythritol and benzene are mixed, phosphorus trichloride is added dropwise under stirring, and the temperature is controlled not to exceed 30° C. After the addition is completed, the mixture is reacted at 70° C. for 4 hours. After the reaction is completed, distillation is performed to obtain dichloropentaerythritol phosphite; S2, dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate and N,N-dimethylformamide were mixed and stirred evenly, reacted at 75° C. for 5 h, and after the reaction was completed, filtered, rotary evaporated, purified by column chromatography, and rotary evaporated to obtain intermediate 1; S3, at room temperature, under nitrogen protection, mix the intermediate 1, N,N-dimethylformamide and potassium carbonate, add 3-aminopropyltriethoxysilane dropwise, the dropping temperature does not exceed 25°C, after the dropping is completed, react at 60°C for 4h, after the reaction is completed, distill under reduced pressure, filter, wash, and vacuum dry to obtain intermediate 2; S4. At room temperature, under nitrogen protection, mix the intermediate 2 and N,N-dimethylformamide, start the stirrer, add dibutyltin oxide, potassium carbonate and epichlorohydrin in sequence, react at 65°C for 6 hours, and after the reaction is completed, distill under reduced pressure, purify by column chromatography, and rotary evaporate to obtain the modifier.

3. The polyurea coating for cable sheath repair according to claim 2, characterized in that: In step S1, the ratio of pentaerythritol, benzene and phosphorus trichloride is 13.6 g:100 mL:28.1 g.

4. The polyurea coating for repairing cable sheath according to claim 2, characterized in that: In step S2, the ratio of the amount of dichloropentaerythritol phosphite, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, potassium carbonate and N,N-dimethylformamide is 27.2 g: 23.6 g: 13.8 g: 100 mL.

5. The polyurea coating for repairing cable sheath according to claim 2, characterized in that: In step S3, the ratio of the amount of intermediate 1, N,N-dimethylformamide, potassium carbonate, and 3-aminopropyltriethoxysilane is 46.4 g: 150 mL: 13.8 g: 22.1 g.

6. The polyurea coating for repairing cable sheath according to claim 2, characterized in that: In step S4, the ratio of the amount of intermediate 2, N,N-dimethylformamide, dibutyltin oxide, potassium carbonate and epichlorohydrin is 64.9 g:150 mL:0.3 g:13.8 g:9.2 g.

7. The method for preparing a polyurea coating for repairing a cable sheath according to claim 1, characterized in that: The following steps are involved: Acetone, isophorone diisocyanate, dimethylol propionic acid and dibutyltin dilaurate are mixed, stirred in a water bath under nitrogen protection, polyetheramine is added, stirred at room temperature, triethylamine is added for neutralization reaction, and finally modified filler, water and defoaming agent are added, stirred to obtain a polyurea coating for cable sheath repair.

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