Low-temperature-resistant protective sleeve for outdoor cable conductor and preparation method of low-temperature-resistant protective sleeve

Abstract

The invention provides a low-temperature-resistant protective sleeve for an outdoor cable conductor and a preparation method of the low-temperature-resistant protective sleeve, and belongs to the technical field of cable protection. Hydroxyl-terminated polydimethylsiloxane, isophorone diisocyanate and a catalyst are subjected to a reaction to obtain a polyurethane prepolymer, the polyurethane prepolymer, a modified chain extender and 3-fluorophenylboronic acid are subjected to a reaction to obtain a mixture, and the mixture is cured to obtain modified polyurethane; and mixing the modified polyurethane, a flame-retardant filler, a styrene elastomer, a plasticizer, a lubricant, an antioxidant and a silane coupling agent, and carrying out melt extrusion molding to obtain the low-temperature-resistant protective jacket. The raw materials are scientifically and reasonably proportioned, the low-temperature-resistant protective sleeve is prepared by using an innovative and rigorous preparation method, and the protective sleeve shows good low-temperature resistance, mechanical property and flame retardant property.

Description

Technical Field

[0001] The present invention relates to the technical field of cable protection, and in particular to a low-temperature resistant protective cover for an outdoor cable conductor and a preparation method thereof. Background Art

[0002] As the outermost protective barrier of a cable system, the performance of the cable sheath directly impacts the safety and durability of the cable in complex environments. With the expansion of cable applications in power, communications, transportation, and other fields, higher requirements are being placed on the low-temperature resistance and flame retardancy of the sheath material.

[0003] Traditional cable sheath materials, such as polyvinyl chloride and polyethylene, are prone to embrittlement and cracking in low-temperature environments, resulting in a sharp decline in mechanical properties. Although some studies have improved low-temperature performance by adding plasticizers, conventional plasticizers are prone to migration and precipitation during long-term use, which in turn accelerates material aging. In addition, the insulation performance of cable sheaths in low-temperature environments may also deteriorate due to material shrinkage or the formation of microcracks, increasing the risk of short circuits. Existing flame retardant technologies mostly rely on halogen-containing flame retardants, such as brominated and chlorinated compounds. Although these materials can effectively slow the spread of flames, they release large amounts of toxic gases such as hydrogen chloride and dioxins when burned. Inorganic flame retardants, such as aluminum hydroxide and magnesium hydroxide, require a higher filling amount to achieve a flame retardant effect, resulting in increased material density and deterioration of processing performance, while significantly reducing the flexibility and impact resistance of the sheath.

[0004] Chinese patent CN 116814012B discloses a low-temperature-resistant chlorinated polyethylene cable sheath material and a preparation method thereof. The chlorinated polyethylene cable sheath material is prepared using chlorinated polyethylene, diisopropylbenzene peroxide, triallyl isocyanurate, an improving additive, an acid absorber, a reinforcing agent, a stabilizer, and an antioxidant as raw materials. The chlorinated polyethylene cable sheath material effectively improves the strength and toughness of the chlorinated polyethylene cable sheath material. However, no dedicated flame retardant is added in this invention, relying solely on the inherent flame retardancy of chlorinated polyethylene. The reinforcing agent may dilute the flame retardant component and reduce the flame retardant effect. Furthermore, no specific flame retardant test data is provided, making it impossible to determine whether the material meets the flame retardant standards. Chinese patent CN 113201188B discloses a low-temperature-resistant protective sheath for underground cables. The sheath is made from silicone rubber, EPDM rubber, white carbon black, a vulcanizer, an accelerator, a plasticizer, and a flame retardant. The low-temperature-resistant sheath exhibits good mechanical properties at room temperature, but its mechanical properties at extreme low temperatures have not been tested. Furthermore, the invention uses decabromodiphenyl ether as a flame retardant, which may pose a risk to the environment.

[0005] Therefore, providing a cable protective sheath with good low temperature resistance and flame retardant properties is an important issue to be solved in this field. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a low-temperature resistant protective cover for outdoor cable conductors and a preparation method thereof. Specifically, the technical solution of the present invention includes the following contents:

[0007] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor, the method comprising the following steps:

[0008] The polyurethane prepolymer is obtained by reacting hydroxy-terminated polydimethylsiloxane, isophorone diisocyanate and a catalyst;

[0009] A polyurethane prepolymer, a modified chain extender and 3-fluorophenylboric acid are reacted to obtain a mixture, and the mixture is cured to obtain a modified polyurethane;

[0010] The modified polyurethane, flame retardant filler, styrene elastomer, plasticizer, lubricant, antioxidant and silane coupling agent are mixed and then melt-extruded to obtain a low-temperature resistant protective cover.

[0011] Furthermore, the preparation method of the modified chain extender comprises the following steps:

[0012] 1,3-diamino-2-propanol, benzaldehyde and p-toluenesulfonic acid are reacted to obtain intermediate product A;

[0013] Intermediate product A, chlorododecane and potassium carbonate are reacted to obtain intermediate product B;

[0014] The intermediate product B is dispersed in a hydrochloric acid ethanol solution to react and prepare a modified chain extender.

[0015] Furthermore, the weight ratio of the 1,3-diamino-2-propanol, benzaldehyde and p-toluenesulfonic acid is 5-6:11-13:0.48-0.52.

[0016] Furthermore, the reaction of 1,3-diamino-2-propanol, benzaldehyde and p-toluenesulfonic acid includes a reaction temperature of 100-110° C. and a reaction time of 6-8 hours.

[0017] Furthermore, the weight ratio of the intermediate product A, chlorododecane and potassium carbonate is 20:15-16:13-14.

[0018] Furthermore, the reaction of the intermediate product A, chlorododecane and potassium carbonate includes a reaction temperature of 80 to 100° C. and a reaction time of 12 to 16 hours.

[0019] Furthermore, the concentration of the hydrochloric acid ethanol solution is 0.1M.

[0020] Furthermore, the preparation method of the flame retardant filler comprises the following steps:

[0021] Pentaerythritol, phosphorus oxychloride and aluminum chloride are reacted to obtain a mixture A;

[0022] Mixture A, melamine and triethylamine are reacted to obtain mixture B;

[0023] Hexagonal boron nitride and isopropyl alcohol were ultrasonically treated to obtain a suspension;

[0024] The suspension, the mixture B and sodium lauryl sulfate are sequentially subjected to ultrasonic mixing and stirring to obtain a flame retardant filler.

[0025] Furthermore, the weight ratio of pentaerythritol, phosphorus oxychloride and aluminum chloride is 1.4-1.8:3-4:0.05-0.08.

[0026] Furthermore, the reaction of pentaerythritol, phosphorus oxychloride and aluminum chloride includes a reaction temperature of 90 to 110° C. and a reaction time of 6 to 8 hours.

[0027] Furthermore, the weight ratio of the mixture A, melamine and triethylamine is 4.2-4.5:1.3-1.6:3.3-3.5.

[0028] Furthermore, the reaction of the mixture A, melamine and triethylamine includes a reaction temperature of 55 to 65° C. and a reaction time of 12 to 18 hours.

[0029] Furthermore, the weight ratio of hexagonal boron nitride, mixture B and sodium lauryl sulfate is 1-2:2-4:0.02-0.04.

[0030] Furthermore, the ultrasonic treatment includes an ultrasonic power of 100 to 200 W and an ultrasonic time of 6 to 12 hours.

[0031] Furthermore, the ultrasonic mixing includes an ultrasonic power of 100 to 200 W and an ultrasonic time of 20 to 30 minutes.

[0032] Furthermore, the stirring reaction of the suspension, mixture B and sodium lauryl sulfate includes a reaction temperature of 90 to 100° C. and a reaction time of 12 to 18 hours.

[0033] Furthermore, the catalyst is dibutyltin dilaurate.

[0034] Furthermore, the weight ratio of the terminal hydroxyl polydimethylsiloxane, isophorone diisocyanate, catalyst, modified chain extender and 3-fluorophenylboric acid is 35-45:11.5-12.5:1.8-2.2:2-2.5:0.6-0.7.

[0035] Furthermore, the reaction of the hydroxy-terminated polydimethylsiloxane, isophorone diisocyanate and catalyst includes a reaction temperature of 75 to 85° C. and a reaction time of 3 to 4 hours.

[0036] Furthermore, the curing includes a curing temperature of 75 to 85° C. and a curing time of 20 to 24 hours.

[0037] Furthermore, the styrene-based elastomer is a hydrogenated styrene-butadiene block copolymer.

[0038] Furthermore, the plasticizer is naphthenic oil.

[0039] Furthermore, the antioxidant is antioxidant 1010.

[0040] Furthermore, the silane coupling agent is 3-aminopropyltriethoxysilane.

[0041] Furthermore, the weight ratio of the modified polyurethane, flame retardant filler, styrene elastomer, plasticizer, lubricant, antioxidant and silane coupling agent is 50-60:5-7:14-18:2-4:1-2:0.1-0.2:1-2.

[0042] Furthermore, the mixing includes a mixing temperature of 110 to 120° C., a mixing speed of 60 to 90 r / min, and a mixing time of 60 to 90 min.

[0043] Furthermore, the melting includes a melting temperature of 190 to 210° C. and a melting time of 3 to 8 minutes.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The present invention obtains a polyurethane prepolymer by reacting terminal hydroxyl polydimethylsiloxane with isophorone diisocyanate, then modifies 1,3-diamino-2-propanol to obtain a modified chain extender, and reacts the modified chain extender and 3-fluorophenylboric acid as a dual chain extender with the polyurethane prepolymer to obtain a modified polyurethane; the side chain of the modified polyurethane contains groups such as ether bonds, long-chain alkyls and fluorine atoms, the ether bonds provide good flexibility for the modified polyurethane, the long-chain alkanes can reduce the intermolecular forces, and their hydrophobicity reduces the microcracks caused by water freezing at low temperatures, and the low surface energy and high bond energy of the fluorine atoms provide good low-temperature flexibility, and the multiple effects synergistically improve the low-temperature impact strength of the low-temperature resistant protective cover, and maintain high flexibility and crack resistance in a low-temperature environment.

[0046] (2) The present invention achieves esterification by nucleophilic substitution between pentaerythritol and phosphorus oxychloride to form a mixture A having a spirocyclic structure, and the mixture A is connected to melamine through a phosphoramide bond to obtain a mixture B. Subsequently, the interlayer force of hexagonal boron nitride is weakened by ultrasonic treatment, and the mixture B is introduced into the interlayer by utilizing intermolecular interaction to obtain a flame retardant filler; the phosphorus and nitrogen elements in the flame retardant filler decompose to generate free radicals such as PO· and NH3 during combustion, and capture the active free radicals of the combustion chain reaction to achieve gas phase flame retardancy. In addition, the polyphosphate generated by pyrolysis promotes the formation of a carbon layer to achieve condensed phase flame retardancy; the high thermal conductivity of hexagonal boron nitride can quickly disperse heat, delay the thermal decomposition of the material, and improve the flame retardancy efficiency. Its lamellar structure can form a dense barrier to hinder the diffusion of oxygen and combustible gas, thereby achieving condensed phase flame retardancy. The multiple effects work together to improve the flame retardancy effect of the low-temperature resistant protective cover.

[0047] (3) The hexagonal boron nitride in the present invention can generate local plasma resonance, promote the reconstruction of surface siloxane groups, and improve the mechanical properties of the low-temperature resistant protective cover; the boric acid ester in the modified polyurethane will decompose to generate boron oxide at high temperature, isolate oxygen and heat, inhibit combustion, and further enhance the flame retardant properties of the low-temperature resistant protective cover. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions of the present invention through the embodiments of the present invention. Obviously, the embodiments described 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 those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0050] Preparation Example 1:

[0051] The preparation method of the modified chain extender comprises the following steps:

[0052] 5 parts by weight of 1,3-diamino-2-propanol are dispersed in 150 parts by weight of anhydrous ethanol, 11 parts by weight of benzaldehyde and 0.48 parts by weight of p-toluenesulfonic acid are added, and the mixture is stirred and reacted at 100° C. for 6 hours in a nitrogen atmosphere. After the reaction, the anhydrous ethanol is removed by vacuum rotary evaporation to obtain an intermediate product A; 20 parts by weight of the intermediate product A, 15 parts by weight of chlorododecane and 13 parts by weight of potassium carbonate are dispersed in 100 parts by weight of N,N-dimethylformamide, and the mixture is stirred and reacted at 80° C. for 12 hours in a nitrogen atmosphere. After the reaction is completed, ice water is added to quench the mixture, the mixture is extracted with ethyl acetate, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by column chromatography to obtain an intermediate product B; 10 parts by weight of the intermediate product B are dispersed in 200 parts by weight of a 0.1M hydrochloric acid ethanol solution, and the mixture is stirred and reacted at 24° C. for 12 hours. After the reaction is completed, the pH is adjusted to 7, the mixture is extracted with ethyl acetate, dried over anhydrous sodium sulfate, and then concentrated by rotary evaporation and purified by column chromatography to obtain a modified chain extender.

[0053] Preparation Example 2:

[0054] The preparation method of the modified chain extender comprises the following steps:

[0055] 5.2 parts by weight of 1,3-diamino-2-propanol were dispersed in 150 parts by weight of anhydrous ethanol, 11.5 parts by weight of benzaldehyde and 0.49 parts by weight of p-toluenesulfonic acid were added, and the mixture was stirred at 103° C. for 6.5 hours in a nitrogen atmosphere. After the reaction, the anhydrous ethanol was removed by vacuum rotary evaporation to obtain an intermediate product A; 20 parts by weight of the intermediate product A, 15.3 parts by weight of chlorododecane and 13.2 parts by weight of potassium carbonate were dispersed in 100 parts by weight of N,N-dimethylformamide, and the mixture was stirred at 85° C. for 13 hours in a nitrogen atmosphere. After the reaction, ice water was added to quench the mixture, and the mixture was extracted with ethyl acetate and dried over anhydrous sodium sulfate. After vacuum concentration, the mixture was purified by column chromatography to obtain an intermediate product B; 10 parts by weight of the intermediate product B were dispersed in 200 parts by weight of a 0.1M hydrochloric acid ethanol solution, and the mixture was stirred at 25° C. for 16 hours. After the reaction, the pH was adjusted to 7, the mixture was extracted with ethyl acetate and dried over anhydrous sodium sulfate, and then concentrated by rotary evaporation and purified by column chromatography to obtain a modified chain extender.

[0056] Preparation Example 3:

[0057] The preparation method of the modified chain extender comprises the following steps:

[0058] 5.7 parts by weight of 1,3-diamino-2-propanol were dispersed in 150 parts by weight of anhydrous ethanol, 12 parts by weight of benzaldehyde and 0.50 parts by weight of p-toluenesulfonic acid were added, and the mixture was stirred at 107° C. for 6.7 hours in a nitrogen atmosphere. After the reaction, the anhydrous ethanol was removed by vacuum rotary evaporation to obtain an intermediate product A; 20 parts by weight of the intermediate product A, 15.5 parts by weight of chlorododecane and 13.6 parts by weight of potassium carbonate were dispersed in 100 parts by weight of N,N-dimethylformamide, and the mixture was stirred at 90° C. for 14 hours in a nitrogen atmosphere. After the reaction, ice water was added to quench the mixture, and the mixture was extracted with ethyl acetate and dried over anhydrous sodium sulfate. After vacuum concentration, the mixture was purified by column chromatography to obtain an intermediate product B; 10 parts by weight of the intermediate product B were dispersed in 200 parts by weight of a 0.1M hydrochloric acid ethanol solution, and the mixture was stirred at 25° C. for 20 hours. After the reaction, the pH was adjusted to 7, the mixture was extracted with ethyl acetate and dried over anhydrous sodium sulfate, and then concentrated by rotary evaporation and purified by column chromatography to obtain a modified chain extender.

[0059] Preparation Example 4:

[0060] The preparation method of the modified chain extender comprises the following steps:

[0061] 6 parts by weight of 1,3-diamino-2-propanol are dispersed in 150 parts by weight of anhydrous ethanol, 13 parts by weight of benzaldehyde and 0.52 parts by weight of p-toluenesulfonic acid are added, and the mixture is stirred and reacted at 110° C. for 8 hours in a nitrogen atmosphere. After the reaction, the anhydrous ethanol is removed by vacuum rotary evaporation to obtain an intermediate product A; 20 parts by weight of the intermediate product A, 16 parts by weight of chlorododecane and 14 parts by weight of potassium carbonate are dispersed in 100 parts by weight of N,N-dimethylformamide, and the mixture is stirred and reacted at 100° C. for 16 hours in a nitrogen atmosphere. After the reaction is completed, ice water is added to quench the mixture, the mixture is extracted with ethyl acetate, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by column chromatography to obtain an intermediate product B; 10 parts by weight of the intermediate product B are dispersed in 200 parts by weight of a 0.1M hydrochloric acid ethanol solution, and the mixture is stirred and reacted at 26° C. for 24 hours. After the reaction is completed, the pH is adjusted to 7, the mixture is extracted with ethyl acetate, dried over anhydrous sodium sulfate, and then concentrated by rotary evaporation and purified by column chromatography to obtain a modified chain extender.

[0062] Preparation Example 5:

[0063] The preparation method of the modified chain extender comprises the following steps:

[0064] 6 parts by weight of 1,3-diamino-2-propanol are dispersed in 150 parts by weight of anhydrous ethanol, 13 parts by weight of benzaldehyde and 0.52 parts by weight of p-toluenesulfonic acid are added, and the mixture is stirred and reacted at 110° C. for 8 hours in a nitrogen atmosphere. After the reaction, the anhydrous ethanol is removed by vacuum rotary evaporation to obtain an intermediate product A; 20 parts by weight of the intermediate product A, 16 parts by weight of isobutyl chloride and 14 parts by weight of potassium carbonate are dispersed in 100 parts by weight of N,N-dimethylformamide, and the mixture is stirred and reacted at 100° C. for 16 hours in a nitrogen atmosphere. After the reaction is completed, ice water is added to quench the mixture, the mixture is extracted with ethyl acetate, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by column chromatography to obtain an intermediate product B; 10 parts by weight of the intermediate product B are dispersed in 200 parts by weight of a 0.1M hydrochloric acid ethanol solution, stirred and reacted at 26° C. for 24 hours. After the reaction is completed, the pH is adjusted to 7, the mixture is extracted with ethyl acetate, dried over anhydrous sodium sulfate, and then concentrated by rotary evaporation and purified by column chromatography to obtain a modified chain extender.

[0065] Preparation Example 6:

[0066] The preparation method of the flame retardant filler comprises the following steps:

[0067] 1.4 parts by weight of pentaerythritol and 0.05 parts by weight of aluminum chloride were dispersed in 50 parts by weight of toluene, stirred and mixed at 60°C for 20 minutes, and then 3 parts by weight of phosphorus oxychloride were added. The temperature was raised to 90°C and stirred in a nitrogen atmosphere for 6 hours. After the reaction, the catalyst was removed by filtration, and the toluene was recovered by vacuum distillation to obtain a crude product. The crude product was washed with ice water, anhydrous ethanol and ether, and then vacuum dried to obtain a mixture A; 4.2 parts by weight of compound A and 1.3 parts by weight of melamine were dispersed in 100 parts by weight of anhydrous tetrahydrofuran and stirred for 15 minutes. 3.3 parts by weight of triethylamine were added in a nitrogen atmosphere and stirred and reacted at 55°C for 12 hours. After the reaction, the mixture was filtered, concentrated and vacuum dried to obtain a mixture B; 1 part by weight of hexagonal boron nitride was dispersed in 1 00 parts by weight of isopropanol were ultrasonically treated at a power of 100 W for 6 hours, and then centrifuged and washed to obtain a suspension. 2 parts by weight of mixture B and 0.02 parts by weight of sodium lauryl sulfate were added, and the mixture was ultrasonically treated at a power of 100 W for 20 minutes in a nitrogen protection environment. The mixture was stirred at 90° C. for 12 hours. After the reaction was completed, the flame retardant filler was obtained by centrifugation, washing and vacuum drying.

[0068] Preparation Example 7:

[0069] The preparation method of the flame retardant filler comprises the following steps:

[0070] 1.5 parts by weight of pentaerythritol and 0.05-0.08 parts by weight of aluminum chloride were dispersed in 50 parts by weight of toluene, stirred and mixed at 62° C. for 23 minutes, and then 3.3 parts by weight of phosphorus oxychloride were added. The temperature was raised to 95° C. and stirred for 6.5 hours in a nitrogen atmosphere. After the reaction, the catalyst was removed by filtration, and toluene was recovered by vacuum distillation to obtain a crude product. The crude product was washed with ice water, anhydrous ethanol and ether, and then vacuum dried to obtain a mixture A. 4.3 parts by weight of compound A and 1.4 parts by weight of melamine were dispersed in 100 parts by weight of anhydrous tetrahydrofuran, stirred and dispersed for 17 minutes, and then stirred and dispersed in a nitrogen atmosphere. 3.4 parts by weight of triethylamine were added in a protective environment, stirred and reacted at 58°C for 14 hours, and after the reaction was completed, the mixture was filtered, concentrated and vacuum dried to obtain a mixture B; 1.3 parts by weight of hexagonal boron nitride were dispersed in 100 parts by weight of isopropanol, ultrasonically treated at a power of 150 W for 8 hours, and then centrifuged and washed to obtain a suspension, 2.5 parts by weight of mixture B and 0.03 parts by weight of sodium lauryl sulfate were added, and the mixture was ultrasonically treated at a power of 120 W for 24 minutes in a nitrogen protective environment, stirred and reacted at 93°C for 14 hours, and after the reaction was completed, the mixture was centrifuged, washed and vacuum dried to obtain a flame retardant filler.

[0071] Preparation Example 8:

[0072] The preparation method of the flame retardant filler comprises the following steps:

[0073] 1.7 parts by weight of pentaerythritol and 0.07 parts by weight of aluminum chloride were dispersed in 50 parts by weight of toluene, stirred and mixed at 68° C. for 27 minutes, and then 3.8 parts by weight of phosphorus oxychloride were added. The temperature was raised to 100° C. and stirred for 7 hours in a nitrogen atmosphere. After the reaction, the catalyst was removed by filtration, and the toluene was recovered by vacuum distillation to obtain a crude product. The crude product was washed with ice water, anhydrous ethanol and ether, and then vacuum dried to obtain a mixture A. 4.4 parts by weight of compound A and 1.5 parts by weight of melamine were dispersed in 100 parts by weight of anhydrous tetrahydrofuran, stirred and dispersed for 22 minutes, and the mixture was heated to 100° C. and stirred and reacted in a nitrogen atmosphere. 3.4 parts by weight of triethylamine were added to the mixture, and the mixture was stirred and reacted at 62° C. for 16 hours. After the reaction, the mixture was filtered, concentrated and vacuum-dried to obtain a mixture B; 1.5 parts by weight of hexagonal boron nitride were dispersed in 100 parts by weight of isopropanol, ultrasonically treated at a power of 170 W for 10 hours, and then centrifuged and washed to obtain a suspension, 3.5 parts by weight of the mixture B and 0.02 parts by weight of sodium lauryl sulfate were added, and the mixture was ultrasonically treated at a power of 150 W for 28 minutes in a nitrogen protection environment, and then stirred and reacted at 98° C. for 16 hours. After the reaction, the mixture was centrifuged, washed and vacuum-dried to obtain a flame retardant filler.

[0074] Preparation Example 9:

[0075] The preparation method of the flame retardant filler comprises the following steps:

[0076] 1.8 parts by weight of pentaerythritol and 0.08 parts by weight of aluminum chloride were dispersed in 50 parts by weight of toluene, stirred and mixed at 70°C for 30 minutes, and then 4 parts by weight of phosphorus oxychloride were added. The temperature was raised to 110°C and stirred in a nitrogen atmosphere for 8 hours. After the reaction, the catalyst was removed by filtration, and the toluene was recovered by vacuum distillation to obtain a crude product. The crude product was washed with ice water, anhydrous ethanol and ether, and then vacuum dried to obtain a mixture A; 4.5 parts by weight of compound A and 1.6 parts by weight of melamine were dispersed in 100 parts by weight of anhydrous tetrahydrofuran and stirred for 25 minutes. 3.5 parts by weight of triethylamine were added in a nitrogen atmosphere, and the mixture was stirred and reacted at 65°C for 18 hours. After the reaction, the mixture was filtered, concentrated and vacuum dried to obtain a mixture B; 2 parts by weight of hexagonal boron nitride were dispersed in 1 00 parts by weight of isopropanol was ultrasonically treated at a power of 200 W for 12 hours, and then centrifuged and washed to obtain a suspension, to which 4 parts by weight of mixture B and 0.04 parts by weight of sodium lauryl sulfate were added, and the mixture was ultrasonically treated at a power of 200 W for 30 minutes in a nitrogen protection environment, and then stirred at 100°C for 18 hours. After the reaction was completed, the flame retardant filler was obtained by centrifugation, washing and vacuum drying.

[0077] Preparation Example 10:

[0078] The preparation method of the flame retardant filler comprises the following steps:

[0079] 1.8 parts by weight of pentaerythritol and 0.08 parts by weight of aluminum chloride are dispersed in 50 parts by weight of toluene, stirred and mixed at 70° C. for 30 minutes, and then 4 parts by weight of phosphorus oxychloride are added. The temperature is raised to 110° C. and stirred in a nitrogen atmosphere for 8 hours. After the reaction is completed, the catalyst is removed by filtration, and the toluene is recovered by vacuum distillation to obtain a crude product. The crude product is washed with ice water, anhydrous ethanol and ether, and then vacuum dried to obtain a mixture A. 4.5 parts by weight of compound A and 1.6 parts by weight of melamine are dispersed in 100 parts by weight of anhydrous tetrahydrofuran and stirred for 25 minutes. 3.5 parts by weight of triethylamine are added in a nitrogen atmosphere, and the mixture is stirred and reacted at 65° C. for 18 hours. After the reaction is completed, the mixture is filtered, concentrated and vacuum dried to obtain a flame retardant filler.

[0080] Preparation Example 11:

[0081] The preparation method of the flame retardant filler comprises the following steps:

[0082] 1.8 parts by weight of pentaerythritol and 0.08 parts by weight of aluminum chloride were dispersed in 50 parts by weight of toluene, stirred and mixed at 70° C. for 30 minutes, and then 4 parts by weight of phosphorus oxychloride were added. The temperature was raised to 110° C. and stirred for 8 hours in a nitrogen atmosphere. After the reaction, the catalyst was filtered to remove the catalyst, and the toluene was recovered by vacuum distillation to obtain a crude product. The crude product was washed with ice water, anhydrous ethanol and ether, respectively, and then vacuum dried to obtain a mixture A. 4.5 parts by weight of compound A and 1.6 parts by weight of melamine were dispersed in 100 parts by weight of anhydrous tetrahydrofuran and stirred for 25 minutes. 3.5 parts by weight of triethylamine were added in a nitrogen atmosphere, and the mixture was stirred and reacted at 65° C. for 18 hours. After the reaction, the mixture was filtered, concentrated and vacuum dried to obtain a mixture B. 2 parts by weight of hexagonal boron nitride, 4 parts by weight of mixture B and 0.04 parts by weight of sodium lauryl sulfate were dispersed in 100 parts by weight of isopropanol, stirred and reacted at 100° C. in a nitrogen atmosphere for 18 hours. After the reaction, the mixture was centrifuged, washed and vacuum dried to obtain a flame retardant filler.

[0083] Example 1:

[0084] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0085] 35 parts by weight of hydroxy-terminated polydimethylsiloxane and 11.5 parts by weight of isophorone diisocyanate were stirred and reacted at 90° C. for 30 minutes. After the reaction, 1.8 parts by weight of dibutyltin dilaurate was added, and the mixture was stirred and reacted at 75° C. for 3 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2 parts by weight of the modified chain extender prepared in Preparation Example 1 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 75° C. for 2 hours, and then heating was stopped to obtain a mixed system. 0.6 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the above mixed system, and stirred for 30 minutes. The reaction liquid is poured into a polytetrafluoroethylene mold and vacuum-exhausted for 25 minutes, then heated to 75°C and cured for 20 hours to obtain a polyurethane matrix; 50 parts by weight of modified polyurethane, 5 parts by weight of flame retardant filler obtained in Preparation Example 6, 14 parts by weight of hydrogenated styrene-butadiene block copolymer, 2 parts by weight of plasticizer, 1 part by weight of lubricant, 0.1 part by weight of antioxidant, and 1 part by weight of silane coupling agent are added to a low-speed mixer, mixed at 110°C and a speed of 60 r / min for 60 minutes to obtain a mixture, which is melted at 190°C for 3 minutes and then extruded into a low-temperature resistant protective cover through a twin-screw extruder.

[0086] Example 2:

[0087] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0088] 37 parts by weight of hydroxy-terminated polydimethylsiloxane and 11.8 parts by weight of isophorone diisocyanate were stirred and reacted at 92°C for 35 minutes. After the reaction, 2.0 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 77°C for 3.2 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.1 parts by weight of the modified chain extender prepared in Preparation Example 2 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 77°C for 2.3 hours, after which heating was stopped to obtain a mixed system. 0.6 to 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system, and stirred for 40 minutes. n to obtain a reaction liquid, which was poured into a polytetrafluoroethylene mold and vacuum-evacuated for 28 minutes, then heated to 78°C and cured for 21 hours to obtain a polyurethane matrix; 52 parts by weight of modified polyurethane, 5.5 parts by weight of the flame retardant filler obtained in Preparation Example 7, 15 parts by weight of hydrogenated styrene-butadiene block copolymer, 2.5 parts by weight of plasticizer, 1.2 parts by weight of lubricant, 0.13 parts by weight of antioxidant, and 1.3 parts by weight of silane coupling agent were added to a low-speed mixer, and mixed at 112°C and a speed of 70 r / min for 70 minutes to obtain a mixture, which was melted at 195°C for 5 minutes and then extruded into a low-temperature-resistant protective cover through a twin-screw extruder.

[0089] Example 3:

[0090] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0091] 52 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.3 parts by weight of isophorone diisocyanate were stirred and reacted at 98° C. for 40 minutes. After the reaction, 2.1 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 82° C. for 3.7 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.3 parts by weight of the modified chain extender prepared in Preparation Example 3 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 82° C. for 2.7 hours, after which heating was stopped to obtain a mixed system. 0.68 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system, and stirred for 50 minutes. The reaction liquid is poured into a polytetrafluoroethylene mold and vacuum-exhausted for 32 minutes, then heated to 81°C and cured for 23 hours to obtain a polyurethane matrix; 57 parts by weight of modified polyurethane, 6 parts by weight of the flame retardant filler obtained in Preparation Example 8, 17 parts by weight of hydrogenated styrene-butadiene block copolymer, 3.5 parts by weight of plasticizer, 1.8 parts by weight of lubricant, 0.18 parts by weight of antioxidant, and 1.5 parts by weight of silane coupling agent are added to a low-speed mixer, mixed at 117°C and a speed of 80 r / min for 80 minutes to obtain a mixture, which is melted at 200°C for 8 minutes and then extruded into a low-temperature resistant protective cover through a twin-screw extruder.

[0092] Example 4:

[0093] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0094] 45 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.5 parts by weight of the modified chain extender prepared in Preparation Example 4 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 85° C. for 3 hours, after which heating was stopped to obtain a mixed system. 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system, and the mixture was stirred and mixed for 60 minutes. in to obtain a reaction liquid, which was poured into a polytetrafluoroethylene mold and vacuum-exhausted for 35 minutes, then heated to 85°C and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 7 parts by weight of the flame retardant filler obtained in Preparation Example 9, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent were added to a low-speed mixer, and mixed at 120°C and a speed of 90 r / min for 90 minutes to obtain a mixture, which was melted at 210°C for 6 minutes and then extruded into a low-temperature resistant protective cover through a twin-screw extruder.

[0095] Comparative Example 1:

[0096] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0097] 45 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.5 parts by weight of the modified chain extender prepared in Preparation Example 5 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 85° C. for 3 hours, after which heating was stopped to obtain a mixed system. 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system, and the mixture was stirred and mixed for 60 minutes. in to obtain a reaction liquid, which was poured into a polytetrafluoroethylene mold and vacuum-exhausted for 35 minutes, then heated to 85°C and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 7 parts by weight of the flame retardant filler obtained in Preparation Example 9, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent were added to a low-speed mixer, and mixed at 120°C and a speed of 90 r / min for 90 minutes to obtain a mixture, which was melted at 210°C for 6 minutes and then extruded into a low-temperature resistant protective cover through a twin-screw extruder.

[0098] Comparative Example 2:

[0099] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0100] 45 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer. 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the polyurethane prepolymer, and the mixture was stirred and reacted for 3 hours to obtain a reaction solution. The reaction solution was poured into a polytetrafluoroethylene mold, vacuum-exhausted for 35 minutes, and then heated to 85° C. ℃ and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 7 parts by weight of flame retardant filler obtained in Preparation Example 9, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent were added to a low-speed mixer, and mixed at 120℃ and a speed of 90r / min for 90min to obtain a mixture. After the mixture was melted at 210℃ for 6min, it was extruded and molded by a twin-screw extruder to obtain a low-temperature resistant protective cover.

[0101] Comparative Example 3:

[0102] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0103] 45 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.5 parts by weight of the modified chain extender prepared in Preparation Example 4 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 85° C. for 3 hours, after which heating was stopped to obtain a mixed system. 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system, and the mixture was stirred and mixed for 60 minutes. n to obtain a reaction liquid, which was poured into a polytetrafluoroethylene mold and vacuum-evacuated for 35 minutes, then heated to 85° C. and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 7 parts by weight of the flame retardant filler obtained in Preparation Example 10, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent were added to a low-speed mixer, mixed at 120° C. and a speed of 90 r / min for 90 minutes to obtain a mixture, which was melted at 210° C. for 6 minutes and then extruded through a twin-screw extruder to obtain a low-temperature resistant protective cover.

[0104] Comparative Example 4:

[0105] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0106] 45 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.5 parts by weight of the modified chain extender prepared in Preparation Example 4 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 85° C. for 3 hours, after which heating was stopped to obtain a mixed system. 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system, and the mixture was stirred and mixed for 60 minutes. n to obtain a reaction liquid, which was poured into a polytetrafluoroethylene mold and vacuum-evacuated for 35 minutes, then heated to 85°C and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 7 parts by weight of the flame retardant filler obtained in Preparation Example 11, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent were added to a low-speed mixer, mixed at 120°C and a speed of 90 r / min for 90 minutes to obtain a mixture, which was melted at 210°C for 6 minutes and then extruded into a low-temperature-resistant protective cover through a twin-screw extruder.

[0107] Comparative Example 5:

[0108] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0109] 45 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.5 parts by weight of the modified chain extender prepared in Preparation Example 4 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 85° C. for 3 hours, and then heating was stopped to obtain a mixed system. 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system. , stirring and mixing for 60 minutes to obtain a reaction liquid, the reaction liquid is poured into a polytetrafluoroethylene mold, vacuum evacuated for 35 minutes, and then heated to 85°C and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent are added to a low-speed mixer, and mixed at 120°C and a speed of 90 r / min for 90 minutes to obtain a mixture, which is melted at 210°C for 6 minutes and then extruded into a low-temperature resistant protective cover through a twin-screw extruder.

[0110] Comparative Example 6:

[0111] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0112] 45 parts by weight of polytetrahydrofuran and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.5 parts by weight of the modified chain extender prepared in Preparation Example 4 were dispersed in 10 parts by weight of acetone to obtain a mixture A, and the mixture A was added to the polyurethane prepolymer and stirred at 85° C. for 3 hours, and then heating was stopped to obtain a mixed system. 0.7 parts by weight of 3-fluorophenylboric acid was dispersed in 20 parts by weight of acetone and added to the mixed system. After stirring for 60 minutes, A reaction liquid was obtained, poured into a polytetrafluoroethylene mold, and vacuum-evacuated for 35 minutes, then heated to 85° C. and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 7 parts by weight of the flame retardant filler obtained in Preparation Example 9, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent were added to a low-speed mixer, mixed at 120° C. and a speed of 90 r / min for 90 minutes to obtain a mixture, which was melted at 210° C. for 6 minutes and then extruded through a twin-screw extruder to obtain a low-temperature resistant protective cover.

[0113] Comparative Example 7:

[0114] A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor comprises the following steps:

[0115] 45 parts by weight of hydroxy-terminated polydimethylsiloxane and 12.5 parts by weight of isophorone diisocyanate were stirred and reacted at 100° C. for 50 minutes. After the reaction, 2.2 parts by weight of dibutyltin dilaurate were added, and the mixture was stirred and reacted at 85° C. for 4 hours in a nitrogen atmosphere to obtain a polyurethane prepolymer; 2.5 parts by weight of the modified chain extender prepared in Preparation Example 4 were dispersed in 10 parts by weight of acetone to obtain a mixture A. The mixture A was added to the polyurethane prepolymer and stirred and reacted at 85° C. for 3 hours to obtain a reaction solution. The reaction solution was poured into a polytetrafluoroethylene mold and vacuum-exhausted for 3 hours. After 5 minutes, the temperature was raised to 85°C and cured for 24 hours to obtain a polyurethane matrix; 60 parts by weight of modified polyurethane, 7 parts by weight of flame retardant filler obtained in Preparation Example 9, 18 parts by weight of hydrogenated styrene-butadiene block copolymer, 4 parts by weight of plasticizer, 2 parts by weight of lubricant, 0.2 parts by weight of antioxidant, and 2 parts by weight of silane coupling agent were added to a low-speed mixer, and mixed at 120°C and a speed of 90r / min for 90 minutes to obtain a mixture. After the mixture was melted at 210°C for 6 minutes, it was extruded into a low-temperature resistant protective cover through a twin-screw extruder.

[0116] Test Example 1:

[0117] The low-temperature resistant protective covers prepared in Examples 1 to 4 and Comparative Examples 1 to 7 were subjected to low-temperature resistance and mechanical property tests:

[0118] Low temperature resistance test: Freeze the low temperature resistant protective cover at -50℃ for 4 hours and observe whether there are cracks on the surface;

[0119] Mechanical properties test: The tensile strength and elongation at break were tested at 25°C and -40°C with reference to GB / T 528-2009 standard. The test results are shown in Table 1.

[0120] Table 1. Mechanical properties test

[0121]

[0122]

[0123] The test results in Table 1 show that the low-temperature-resistant protective covers prepared in Examples 1 to 4 of the present invention have good low-temperature resistance and mechanical properties, and can maintain good flexibility even in a -40°C environment. The reason why Comparative Examples 1, 2, and 7 have poor low-temperature resistance and mechanical properties at -40°C may be that the molecular structure of the modified polyurethane lacks ether bonds, long-chain alkanes, or fluorine atoms, which prevents the components in the low-temperature-resistant protective cover from exerting a synergistic effect and maintaining good mechanical properties in a low-temperature environment.

[0124] Test Example 2:

[0125] Flame retardancy test: Referring to GB / T 2406.2-2009 standard, the flame retardancy of the low-temperature resistant protective covers prepared in Examples 1 to 4 and Comparative Examples 1 to 7 was tested. The test results are shown in Table 2.

[0126] Table 2. Flame retardancy test

[0127] Limiting oxygen index (%) Example 1 37.4 Example 2 37.9 Example 3 38.3 Example 4 38.6 Comparative Example 1 30.5 Comparative Example 2 26.4 Comparative Example 3 22.3 Comparative Example 4 23.8 Comparative Example 5 19.5 Comparative Example 6 28.4 Comparative Example 7 24.7

[0128] The test results in Table 2 show that the low-temperature-resistant protective covers prepared in Examples 1 to 4 of the present invention have good flame retardant properties. The decrease in flame retardant properties in Comparative Example 3 may be due to the lack of hexagonal boron nitride, which cannot form a dense barrier and cannot hinder the diffusion of oxygen and combustible gases, resulting in a decrease in flame retardant efficiency. The decrease in flame retardant properties in Comparative Example 4 may be due to the lack of ultrasonic treatment of hexagonal boron nitride, and its stacking layers cannot be fully mixed with borax and boron nitride, thereby affecting the flame retardant effect.

[0129] To sum up, the present invention prepares a low-temperature resistant protective cover by scientifically and rationally proportioning the raw materials and using an innovative and rigorous preparation method. The protective cover exhibits good low-temperature resistance and can effectively resist low-temperature invasion; at the same time, it has good mechanical properties and is not prone to cracking; in addition, the protective cover also has good flame retardant properties, which can reduce the risk of damage to the cable caused by fire hazards.

[0130] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a low-temperature resistant protective cover for an outdoor cable conductor, characterized in that: The preparation method comprises the following steps: The polyurethane prepolymer is obtained by reacting hydroxy-terminated polydimethylsiloxane, isophorone diisocyanate and a catalyst; A polyurethane prepolymer, a modified chain extender and 3-fluorophenylboric acid are reacted to obtain a mixture, and the mixture is cured to obtain a modified polyurethane; The modified polyurethane, flame retardant filler, styrene elastomer, plasticizer, lubricant, antioxidant and silane coupling agent are mixed and then melt-extruded to obtain a low-temperature resistant protective cover.

2. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor according to claim 1, characterized in that: The preparation method of the modified chain extender comprises the following steps: 1,3-diamino-2-propanol, benzaldehyde and p-toluenesulfonic acid are reacted to obtain intermediate product A; Intermediate product A, chlorododecane and potassium carbonate are reacted to obtain intermediate product B; The intermediate product B is dispersed in a hydrochloric acid ethanol solution to react and prepare a modified chain extender.

3. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor as claimed in claim 2, characterized in that: The reaction of the intermediate product A, chlorododecane and potassium carbonate includes a reaction temperature of 80 to 100° C. and a reaction time of 12 to 16 hours.

4. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor according to claim 1, characterized in that: The preparation method of the flame retardant filler comprises the following steps: Pentaerythritol, phosphorus oxychloride and aluminum chloride are reacted to obtain a mixture A; Mixture A, melamine and triethylamine are reacted to obtain mixture B; Hexagonal boron nitride and isopropyl alcohol are subjected to ultrasonic treatment to obtain a suspension, and the suspension, mixture B and sodium lauryl sulfate are sequentially subjected to ultrasonic mixing and stirring to obtain a flame retardant filler.

5. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor as claimed in claim 4, characterized in that: The ultrasonic treatment includes an ultrasonic power of 100 to 200 W and an ultrasonic time of 6 to 12 hours.

6. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor according to claim 1, characterized in that: The styrene-based elastomer is a hydrogenated styrene-butadiene block copolymer.

7. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor according to claim 1, characterized in that: The plasticizer is naphthenic oil.

8. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor according to claim 1, characterized in that: The antioxidant is antioxidant 1010.

9. The method for preparing a low-temperature resistant protective cover for an outdoor cable conductor according to claim 1, characterized in that: The weight ratio of the modified polyurethane, flame retardant filler, styrene elastomer, plasticizer, lubricant, antioxidant and silane coupling agent is 50-60:5-7:14-18:2-4:1-2:0.1-0.2:1-2.

10. A low temperature resistant protective cover, characterized in that: The low-temperature resistant protective sleeve for outdoor cable conductors is prepared by the preparation method of any one of claims 1 to 9.

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