Aging-resistant material for rail transit cables and preparation method thereof

Abstract

The invention relates to the technical field of cable materials and discloses an aging-resistant material for rail transit cables and a preparation method thereof. The aging-resistant material comprises 100 parts by weight of polyurethane, 20-30 parts by weight of heat-resistant and aging-resistant polyurethane, 12-15 parts by weight of expanded graphite and 0.2-0.5 parts by weight of an antioxidant, which are obtained through kneading, thin-passing and calendering. The heat-resistant and aging-resistant polyurethane is synthesized by using prepared diol naphthalene organosilicon-modified TiO2 as a chain extender, and has both the heat-resistant aging performance of a naphthalene ring and the anti-ultraviolet aging performance of TiO2. Meanwhile, the organosiloxane and the expanded graphite give the heat-resistant and aging-resistant polyurethane excellent flame-retardant and smoke-suppressing performance. The heat-resistant and aging-resistant polyurethane is stably present in a polyurethane matrix for a long time by chemical grafting, is not prone to migration and exudation, and thus ensures the long-term aging-resistant effect of the polyurethane cable material. The preparation method has a simple process flow and is easy to be industrialized on a large scale.

Description

Technical Field

[0001] The present invention relates to the technical field of cable materials, in particular to an aging-resistant material for rail transit cables and a preparation method thereof. Background Art

[0002] With the rapid development of the modern rail transit industry, rail transit cables, as important components for connecting and transmitting power and signals, are of vital importance for their performance stability and reliability. However, due to the long-term exposure of rail transit cables to complex and changeable environments such as high temperature, high humidity, strong ultraviolet radiation and chemical corrosion, some traditional cable materials are prone to aging during long-term use, resulting in a decline in cable performance, and are prone to cracking or brittleness, and even causing safety hazards. The aging resistance of cable materials has become a key factor affecting their service life and performance. Therefore, it is particularly important to develop a rail transit cable material with excellent aging resistance.

[0003] Because the synthetic raw materials of thermoplastic polyurethane are all difunctional, there is basically no chemical crosslinking between its molecular chains. Therefore, its processing properties, mechanical properties, and low-temperature performance are very outstanding, and it is widely used in the wire and cable industry. However, during long-term use, polyurethane is easily affected by environmental factors, resulting in problems such as material aging, hardening, and cracking, thereby affecting the transmission performance and safety of the cable. In the prior art, in order to improve the aging resistance of polyurethane cable materials, additives such as antioxidants and UV absorbers are generally added, and modification techniques such as blending and crosslinking are adopted. However, these methods are limited in effectiveness and often lead to increased cable material costs. Patent No. CN118344553A discloses a flame-retardant polyurethane material for cable materials and a method for manufacturing the same. By preparing a chain extender containing a silicon-phosphorus flame retardant component and an active hydroxyl group in its structure, the polyurethane chain is extended, thereby introducing a silicon-phosphorus synergistic flame retardant component into the polyurethane structure. The resulting polyurethane material has good flame retardancy, but poor UV resistance. After long-term outdoor conditions, the performance of the cable material is significantly degraded.

[0004] TiO2 has good potential for absorbing, reflecting and refracting ultraviolet radiation, but its high hydrophilicity and polarity make it prone to aggregation and low dispersibility, making it difficult to disperse evenly in polyurethane. The existing technology often uses high-speed stirring and ultrasonic dispersion to temporarily disperse it evenly. However, the interaction force between nanoparticles is much stronger than the interaction between nanoparticles and polyurethane polymers. The present invention aims to introduce naphthalene with good heat resistance and nano-TiO2 with good UV resistance into the polyurethane chain extender, and make it stably present in the polyurethane matrix for a long time through chemical grafting. It works synergistically with expanded graphite, is less likely to migrate and seep out, and ensures the long-term aging resistance of the polyurethane material. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and to provide an aging-resistant material for rail transit cables and a preparation method thereof, so as to improve the problem that the cable materials in the prior art have poor resistance to ultraviolet aging and heat aging, and have excellent mechanical properties and a long service life.

[0006] The present invention is achieved through the following technical solutions:

[0007] The preparation method of the aging-resistant material for rail transit cables is carried out according to the following steps:

[0008] Step (1), under a nitrogen atmosphere, vacuum dehydrating 100 parts of polyether polyol by weight at 110-120 ° C for 1-3 hours, cooling to 50-65 ° C, adding 20-30 parts of toluene diisocyanate and 0.5-0.8 parts of dibutyltin dilaurate, reacting at 75-90 ° C for 2-5 hours, then adding 2-10 parts of diol naphthalene silicone modified TiO2, continuing to react for 0.5-1 hour, adding triethylamine to adjust the pH to 7-8, adding 10-15 parts of dimethylthiotoluene diamine for curing, and obtaining a heat-resistant and aging-resistant polyurethane.

[0009] Step (2), placing 100 parts of polyurethane and 20-30 parts of heat-resistant and aging-resistant polyurethane in parts by weight in a high-speed kneader, kneading at 100-110° C. for 35-50 minutes, then adding 12-15 parts of expanded graphite and 0.2-0.5 parts of antioxidant, heating to 190-210° C. and kneading for 20-30 minutes, transferring the mixture to an open mill and thinning it 4-6 times, cooling the material, discharging the material, and calendering to obtain an aging-resistant material for rail transit cables.

[0010] Preferably, the polyether polyol in step (1) is polycarbonate diol with a molecular weight of 2000.

[0011] Preferably, the antioxidant in step (2) is a mixture of antioxidant 168 and antioxidant 1010 in a mass ratio of 0.5:1.

[0012] Preferably, the preparation method of diol naphthalene organosilicon-modified TiO2 in step (1) is carried out according to the following steps:

[0013] Step S1: Under a nitrogen atmosphere, methylvinyldichlorosilane and toluene were added to a reaction flask, and after stirring, 2-hydroxy-6-methoxynaphthalene and sodium hydride were added, and the mixture was stirred for reaction. After the reaction was completed, the mixture was cooled and filtered, washed with saturated brine, and purified by column chromatography (n-heptane / ethyl acetate = 8:1). The organic phase was concentrated to obtain dimethoxynaphthalene organosilicon.

[0014] Step S2: under a nitrogen atmosphere, add dimethoxynaphthalene organosilicon and methanol to a reaction flask, stir evenly, add bis[3-(trimethoxysilyl)propyl]amine, react at 45-60° C. for 8-16 hours, and distill under reduced pressure to obtain a dimethoxynaphthalene organosilicon coupling agent.

[0015] Step S3: Under a nitrogen atmosphere, nano-TiO2, ethanol and deionized water are added to a reaction flask. After uniform dispersion, dimethoxynaphthalene organosilicon coupling agent is added, and the pH of the system is adjusted to 3-5 with glacial acetic acid. Ultrasonic reaction is carried out at a temperature of 50-70°C and a power of 100-120Hz for 20-40min. The mixture is filtered, washed, and dried under reduced pressure. Then, the mixture is dispersed in dichloromethane, and boron tribromide is added dropwise. The mixture is reacted at room temperature for 12-24h, filtered, and washed with ethanol to obtain diolnaphthalene organosilicon-modified TiO2.

[0016] Preferably, in step S1, the molar ratio of methylvinyldichlorosilane, 2-hydroxy-6-methoxynaphthalene, and sodium hydride is 1 mol: (2.05-2.2) mol: (2.3-2.5) mol.

[0017] Preferably, the reaction temperature in step S1 is 80-100° C., and the reaction time is 5-10 h.

[0018] Preferably, in step S2, the molar ratio of dimethoxynaphthalene organosilicon and bis[3-(trimethoxysilyl)propyl]amine is 1 mol:(1.1-1.25) mol.

[0019] Preferably, in step S3, the ratio of nano-TiO2, dimethoxynaphthalene organosilicon coupling agent, and boron tribromide is 1g:(0.2-0.4)g:(0.9-1.2)g.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) As an inorganic material, nano-TiO2 itself has high hardness and strength. When it is evenly dispersed in the polyurethane matrix, it can play a reinforcing role like a "micro-reinforcer". These nanoparticles can absorb and disperse external forces, thereby slowing down the deformation and destruction process of the polyurethane matrix; at the same time, the addition of silicone can enable the material to better disperse and withstand stress when subjected to external forces, thereby improving the mechanical strength of the cable material.

[0022] (2) Nano-TiO2 has a small particle size and can be evenly dispersed in the polyurethane matrix as a chain extender by chemical grafting. It can reflect and scatter ultraviolet rays, as well as absorb ultraviolet rays, thus having a stronger barrier ability to ultraviolet rays and forming an effective ultraviolet barrier layer. When TiO2 is irradiated by ultraviolet light, its valence band electrons can gain energy and jump to the conduction band, thereby forming photogenerated electrons. The photogenerated electrons are captured by oxygen in the air to generate superoxide radicals, which can oxidize organic pollutants to generate carbon dioxide and water. Therefore, nano-TiO2 has a good absorption of ultraviolet light. The absorption and scattering of ultraviolet light constitute a shielding effect on ultraviolet light, reducing the damage of ultraviolet light to polyurethane materials and improving the anti-ultraviolet aging performance of cable materials.

[0023] (3) The naphthalene ring is a highly rigid conjugated system in which the π electron cloud is distributed relatively evenly, which makes the naphthalene ring structure relatively stable and not easily decomposed by thermal or chemical attacks. Introducing it into the polyurethane molecular chain can improve the regularity and symmetry of the hard segment, making it less likely to deform or flow at high temperatures, so that it can still maintain good mechanical properties at high temperatures; at the same time, the bond energy of organic siloxane is large, the thermal decomposition temperature is high, and the heat resistance is good, which further improves the heat aging resistance of polyurethane cable materials.

[0024] (4) The organosilicon in the diol naphthalene organosilicon-modified TiO2 is decomposed by heat during the combustion process to produce inorganic substances such as SiO2; the expanded graphite can rapidly expand hundreds of times at high temperatures to form a fluffy carbonaceous protective layer, which can isolate oxygen and heat and prevent the spread of flames. The protective layer formed by the organosilicon is denser and smoother, while the protective layer formed by the expanded graphite is more fluffy and porous. The two protective layers are superimposed on each other to form a thicker and more effective flame retardant barrier; after modification, nano-TiO2 can not only promote dispersion and reduce the negative mechanical effects of agglomeration on polyurethane, but also interact with modified polyurethane; the cable material prepared by the present invention has an inorganic and organic multi-effect flame retardant mechanism, which further improves the flame retardant properties of the cable material. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the examples. It should be understood that the specific examples described herein are merely for the purpose of explaining the present application and are not intended to limit the present application. Unless otherwise indicated, the raw materials and reagents used in the present application are all commercially available products or can be prepared by known methods.

[0026] Methylvinyldichlorosilane, CAS number 124-70-9.

[0027] 2-Hydroxy-6-methoxynaphthalene, CAS number is 5111-66-0.

[0028] Bis[3-(trimethoxysilyl)propyl]amine, CAS number 82985-35-1.

[0029] Example 1

[0030] (1) Under nitrogen atmosphere, 45 mmol of methylvinyldichlorosilane and 270 mL of toluene were added to a reaction flask, stirred evenly, and then 95.4 mmol of 2-hydroxy-6-methoxynaphthalene and 108 mmol of sodium hydride were added. The mixture was reacted at 90° C. for 8 h, cooled and filtered, washed with saturated brine, purified by column chromatography (n-heptane / ethyl acetate = 8:1), and the organic phase was concentrated to obtain dimethoxynaphthalene organosilicon. The preparation reaction formula is as follows:

[0031]

[0032] (2) Under nitrogen atmosphere, 40 mmol of dimethoxynaphthalene organosilicon and 500 mL of methanol were added to a reaction flask. After stirring evenly, 46 mmol of bis[3-(trimethoxysilyl)propyl]amine was added. The mixture was reacted at 55°C for 12 hours and then distilled under reduced pressure to obtain a dimethoxynaphthalene organosilicon coupling agent. The preparation reaction formula is as follows:

[0033]

[0034] (3) Under nitrogen atmosphere, 10 g of nano-TiO2, 180 mL of ethanol and 45 mL of deionized water were added to a reaction flask. After uniform dispersion, 2.4 g of dimethoxynaphthalene organosilicon coupling agent was added. The pH of the system was adjusted to 4 with glacial acetic acid. Ultrasonic reaction was carried out at a temperature of 60 ° C and a power of 110 Hz for 30 min. The mixture was filtered, washed, and dried under reduced pressure. Then, the mixture was dispersed in 250 mL of dichloromethane, 10.5 g of boron tribromide was added dropwise, and the mixture was reacted at room temperature for 16 h. The mixture was filtered and washed with ethanol to obtain diolnaphthalene organosilicon-modified TiO2.

[0035] (4) Under nitrogen atmosphere, 100 g of polycarbonate diol with a molecular weight of 2000 was vacuum dehydrated at 115 ° C for 2 h, cooled to 60 ° C, and 25 g of toluene diisocyanate and 0.6 g of dibutyltin dilaurate were added. The reaction was carried out at 85 ° C for 4 h, and then 2 g of diol naphthalene silicone modified TiO2 was added. The reaction was continued for 1 h, triethylamine was added to adjust the pH to 8, and 12 g of dimethylthiotoluene diamine was added for curing to obtain heat-resistant and aging-resistant polyurethane.

[0036] (5) 100 g of polyurethane and 20 g of heat-resistant and anti-aging polyurethane were placed in a high-speed kneader and kneaded at 105 °C for 40 min. Then, 12 g of expanded graphite and 0.35 g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added, and the mixture was heated to 200 °C and kneaded for 25 min. The mixture was transferred to an open mill and thinned 5 times. The mixture was cooled, discharged, and calendered to obtain an aging-resistant material for rail transit cables.

[0037] Example 2

[0038] (1) Under nitrogen atmosphere, 150 mmol of methylvinyldichlorosilane and 750 mL of toluene were added to a reaction flask, stirred evenly, and then 307.5 mmol of 2-hydroxy-6-methoxynaphthalene and 345 mmol of sodium hydride were added. The mixture was reacted at 100° C. for 5 h, cooled and filtered, washed with saturated brine, purified by column chromatography (n-heptane / ethyl acetate = 8:1), and the organic phase was concentrated to obtain dimethoxynaphthalene organosilicon.

[0039] (2) Under nitrogen atmosphere, 130 mmol of dimethoxynaphthalene organosilicon and 1300 mL of methanol were added to a reaction flask. After stirring evenly, 143 mmol of bis[3-(trimethoxysilyl)propyl]amine was added. The mixture was reacted at 60°C for 8 h and then distilled under reduced pressure to obtain a dimethoxynaphthalene organosilicon coupling agent.

[0040] (3) Under nitrogen atmosphere, 10 g of nano-TiO2, 150 mL of ethanol and 35 mL of deionized water were added to a reaction flask. After uniform dispersion, 2.8 g of dimethoxynaphthalene organosilicon coupling agent was added. The pH of the system was adjusted to 5 with glacial acetic acid. Ultrasonic reaction was carried out at a temperature of 70 ° C and a power of 120 Hz for 20 min. The mixture was filtered, washed, and dried under reduced pressure. Then, the mixture was dispersed in 250 mL of dichloromethane, 9 g of boron tribromide was added dropwise, and the mixture was reacted at room temperature for 12 h. The mixture was filtered and washed with ethanol to obtain diolnaphthalene organosilicon-modified TiO2.

[0041] (4) Under nitrogen atmosphere, 100 g of polycarbonate diol with a molecular weight of 2000 was vacuum dehydrated at 120 ° C for 1 h, cooled to 65 ° C, and 20 g of toluene diisocyanate and 0.5 g of dibutyltin dilaurate were added. The reaction was carried out at 90 ° C for 2 h, and then 4 g of diol naphthalene silicone modified TiO2 was added. The reaction was continued for 0.5 h, triethylamine was added to adjust the pH to 7, and 10 g of dimethylthiotoluene diamine was added for curing to obtain heat-resistant and anti-aging polyurethane.

[0042] (5) 100 g of polyurethane and 23 g of heat-resistant and anti-aging polyurethane were placed in a high-speed kneader and kneaded at 110 °C for 35 min. Then, 12 g of expanded graphite and 0.2 g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added, and the mixture was heated to 210 °C and kneaded for 20 min. The mixture was transferred to an open mill and thinned 4 times. The mixture was cooled, discharged, and calendered to obtain an aging-resistant material for rail transit cables.

[0043] Example 3

[0044] (1) Under nitrogen atmosphere, 30 mmol of methylvinyldichlorosilane and 240 mL of toluene were added to a reaction flask, stirred evenly, and then 66 mmol of 2-hydroxy-6-methoxynaphthalene and 75 mmol of sodium hydride were added. The mixture was reacted at 80° C. for 10 h, cooled and filtered, washed with saturated brine, purified by column chromatography (n-heptane / ethyl acetate = 8:1), and the organic phase was concentrated to obtain dimethoxynaphthalene organosilicon.

[0045] (2) Under nitrogen atmosphere, 25 mmol of dimethoxynaphthalene organosilicon and 375 mL of methanol were added to a reaction flask. After stirring evenly, 31.25 mmol of bis[3-(trimethoxysilyl)propyl]amine was added. The mixture was reacted at 45°C for 16 h and then distilled under reduced pressure to obtain a dimethoxynaphthalene organosilicon coupling agent.

[0046] (3) Under nitrogen atmosphere, 10 g of nano-TiO2, 200 mL of ethanol and 50 mL of deionized water were added to a reaction flask. After uniform dispersion, 3.2 g of dimethoxynaphthalene organosilicon coupling agent was added. The pH of the system was adjusted to 3 with glacial acetic acid. Ultrasonic reaction was carried out at a temperature of 50 ° C and a power of 100 Hz for 40 min. The mixture was filtered, washed, and dried under reduced pressure. Then, the mixture was dispersed in 250 mL of dichloromethane, 12 g of boron tribromide was added dropwise, and the mixture was reacted at room temperature for 24 h. The mixture was filtered and washed with ethanol to obtain diolnaphthalene organosilicon-modified TiO2.

[0047] (4) Under nitrogen atmosphere, 100 g of polycarbonate diol with a molecular weight of 2000 was vacuum dehydrated at 120 ° C for 3 h, cooled to 50 ° C, and 30 g of toluene diisocyanate and 0.8 g of dibutyltin dilaurate were added. The reaction was carried out at 75 ° C for 5 h, and then 6 g of diol naphthalene silicone modified TiO2 was added. The reaction was continued for 0.5 h, triethylamine was added to adjust the pH to 8, and 15 g of dimethylthiotoluene diamine was added for curing to obtain heat-resistant and aging-resistant polyurethane.

[0048] (5) 100 g of polyurethane and 26 g of heat-resistant and anti-aging polyurethane were placed in a high-speed kneader and kneaded at 100 °C for 50 min. Then, 15 g of expanded graphite and 0.5 g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added, and the mixture was heated to 190 °C and kneaded for 30 min. The mixture was transferred to an open mill and thinned 4 times. The mixture was cooled, discharged, and calendered to obtain an aging-resistant material for rail transit cables.

[0049] Example 4

[0050] (1) Under nitrogen atmosphere, 80 mmol of methylvinyldichlorosilane and 520 mL of toluene were added to a reaction flask, stirred evenly, and then 172 mmol of 2-hydroxy-6-methoxynaphthalene and 188 mmol of sodium hydride were added. The mixture was reacted at 95° C. for 8 h, cooled and filtered, washed with saturated brine, purified by column chromatography (n-heptane / ethyl acetate = 8:1), and the organic phase was concentrated to obtain dimethoxynaphthalene organosilicon.

[0051] (2) Under nitrogen atmosphere, 75 mmol of dimethoxynaphthalene organosilicon and 1050 mL of methanol were added to a reaction flask. After stirring evenly, 90 mmol of bis[3-(trimethoxysilyl)propyl]amine was added. The mixture was reacted at 55°C for 15 h and then distilled under reduced pressure to obtain a dimethoxynaphthalene organosilicon coupling agent.

[0052] (3) Under nitrogen atmosphere, 10 g of nano-TiO2, 175 mL of ethanol and 45 mL of deionized water were added to a reaction flask. After uniform dispersion, 3.6 g of dimethoxynaphthalene organosilicon coupling agent was added. The pH of the system was adjusted to 3.5 with glacial acetic acid. Ultrasonic reaction was carried out at a temperature of 65 ° C and a power of 110 Hz for 35 min. The mixture was filtered, washed, and dried under reduced pressure. Then, the mixture was dispersed in 250 mL of dichloromethane, 11 g of boron tribromide was added dropwise, and the mixture was reacted at room temperature for 20 h. The mixture was filtered and washed with ethanol to obtain diolnaphthalene organosilicon-modified TiO2.

[0053] (4) Under nitrogen atmosphere, 100 g of polycarbonate diol with a molecular weight of 2000 was vacuum dehydrated at 115 ° C for 2 h, cooled to 60 ° C, and 28 g of toluene diisocyanate and 0.65 g of dibutyltin dilaurate were added. The reaction was carried out at 85 ° C for 4 h, and then 8 g of diol naphthalene silicone modified TiO2 was added. The reaction was continued for 0.5 h, triethylamine was added to adjust the pH to 7, and 13 g of dimethylthiotoluene diamine was added for curing to obtain heat-resistant and aging-resistant polyurethane.

[0054] (5) 100 g of polyurethane and 28 g of heat-resistant and anti-aging polyurethane were placed in a high-speed kneader and kneaded at 105 °C for 40 min. Then, 15 g of expanded graphite and 0.5 g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added, and the mixture was heated to 205 °C and kneaded for 22 min. The mixture was transferred to an open mill and thinned 5 times. The mixture was cooled, discharged, and calendered to obtain an aging-resistant material for rail transit cables.

[0055] Example 5

[0056] (1) Under nitrogen atmosphere, 25 mmol of methylvinyldichlorosilane and 170 mL of toluene were added to a reaction flask, stirred evenly, and then 54 mmol of 2-hydroxy-6-methoxynaphthalene and 59 mmol of sodium hydride were added. The mixture was reacted at 95° C. for 9 h, cooled and filtered, washed with saturated brine, purified by column chromatography (n-heptane / ethyl acetate = 8:1), and the organic phase was concentrated to obtain dimethoxynaphthalene organosilicon.

[0057] (2) Under nitrogen atmosphere, 20 mmol of dimethoxynaphthalene organosilicon and 280 mL of methanol were added to a reaction flask. After stirring evenly, 23 mmol of bis[3-(trimethoxysilyl)propyl]amine was added. The mixture was reacted at 50°C for 12 h and then distilled under reduced pressure to obtain a dimethoxynaphthalene organosilicon coupling agent.

[0058] (3) Under nitrogen atmosphere, 10 g of nano-TiO2, 185 mL of ethanol and 40 mL of deionized water were added to a reaction flask. After uniform dispersion, 4 g of dimethoxynaphthalene organosilicon coupling agent was added. The pH of the system was adjusted to 5 with glacial acetic acid. Ultrasonic reaction was carried out at a temperature of 65 ° C and a power of 120 Hz for 40 min. The mixture was filtered, washed, and dried under reduced pressure. Then, the mixture was dispersed in 250 mL of dichloromethane, 10.5 g of boron tribromide was added dropwise, and the mixture was reacted at room temperature for 20 h. The mixture was filtered and washed with ethanol to obtain diolnaphthalene organosilicon-modified TiO2.

[0059] (4) Under nitrogen atmosphere, 100 g of polycarbonate diol with a molecular weight of 2000 was vacuum dehydrated at 120 ° C for 3 h, cooled to 60 ° C, and 25 g of toluene diisocyanate and 0.8 g of dibutyltin dilaurate were added. The reaction was carried out at 80 ° C for 5 h, and then 10 g of diol naphthalene organosilicon-modified TiO2 was added. The reaction was continued for 1 h, triethylamine was added to adjust the pH to 7, and 12 g of dimethylthiotoluene diamine was added for curing to obtain a heat-resistant and anti-aging polyurethane.

[0060] (5) 100 g of polyurethane and 30 g of heat-resistant and anti-aging polyurethane were placed in a high-speed kneader and kneaded at 110 °C for 45 min. Then, 13 g of expanded graphite and 0.5 g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added, and the mixture was heated to 205 °C and kneaded for 25 min. The mixture was transferred to an open mill and thinned 6 times. The mixture was cooled, discharged, and calendered to obtain an aging-resistant material for rail transit cables.

[0061] Comparative Example 1

[0062] (1) Under nitrogen atmosphere, 10 g of dimethoxynaphthalene organosilicon (prepared in Example 1) was added to a reaction flask and dispersed in 250 mL of dichloromethane. 10.5 g of boron tribromide was added dropwise. The mixture was reacted at room temperature for 16 h, filtered, and washed with ethanol to obtain diolnaphthalene organosilicon.

[0063] (2) Under nitrogen atmosphere, 100 g of polycarbonate diol with a molecular weight of 2000 was vacuum dehydrated at 115 ° C for 2 h, cooled to 60 ° C, and 25 g of toluene diisocyanate and 0.6 g of dibutyltin dilaurate were added. The reaction was carried out at 85 ° C for 4 h, and then 2 g of diol naphthalene silicone was added. The reaction was continued for 1 h, triethylamine was added to adjust the pH to 8, and 12 g of dimethylthiotoluene diamine was added for curing to obtain a heat-resistant polyurethane.

[0064] (3) 100 g of polyurethane and 20 g of heat-resistant polyurethane were placed in a high-speed kneader and kneaded at 105 °C for 40 min. Then, 12 g of expanded graphite and 0.35 g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added, and the mixture was heated to 200 °C and kneaded for 25 min. The mixture was transferred to an open mill and thinned 5 times. The mixture was cooled, discharged, and calendered to obtain a rail transit cable material.

[0065] Comparative Example 2

[0066] (1) Under nitrogen atmosphere, 100 g of polycarbonate diol with a molecular weight of 2000 was vacuum dehydrated at 115 ° C for 2 h, cooled to 60 ° C, and 25 g of toluene diisocyanate and 0.6 g of dibutyltin dilaurate were added. The mixture was reacted at 85 ° C for 4 h, and then 2 g of nano-TiO2 was added. The reaction was continued for 1 h, triethylamine was added to adjust the pH to 8, and 12 g of dimethylthiotoluene diamine was added for curing to obtain anti-aging polyurethane.

[0067] (2) 100 g of polyurethane and 20 g of anti-aging polyurethane were placed in a high-speed kneader and kneaded at 105 °C for 40 min. Then, 12 g of expanded graphite and 0.35 g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added, and the mixture was heated to 200 °C and kneaded for 25 min. The mixture was transferred to an open mill and thinned 5 times. The mixture was cooled, discharged, and calendered to obtain a rail transit cable material.

[0068] Comparative Example 3

[0069] 120g of polyurethane was placed in a high-speed kneader and kneaded at 105°C for 40 minutes. Then, 12g of expanded graphite and 0.35g of a mixture of antioxidant 168 and antioxidant 1010 with a mass ratio of 0.5:1 were added. The temperature was raised to 200°C and kneaded for 25 minutes. The mixture was transferred to an open mill and thinned 5 times. The mixture was cooled, discharged, and calendered to obtain a rail transit cable material.

[0070] UV aging resistance test: tensile strength was tested in accordance with GB / T 1040.1-2018 standard using an electronic universal testing machine; accelerated aging test was carried out in accordance with AST-MG154 standard in a LUV-2 type UV accelerated aging test chamber, with the test specimens exposed to UVB (313nm, 75W / m 2 ), irradiated at 60°C for 4h, then sprayed with deionized water at 50°C for 4h, and the cycle was repeated for 1000h; wherein the decrease in Ts = (Ts before UV aging - Ts after UV aging) / Ts before UV aging × 100%.

[0071] Table 1 UV aging performance test

[0072]

[0073] From the test results in Table 1, it can be seen that with the increase of the content of diol naphthalene silicone-modified TiO2, the tensile strength of the cable material gradually increases. This is because nano-TiO2, as an inorganic material, has high hardness and strength. When it is evenly dispersed in polyurethane, it can play a reinforcing role like a "micro-reinforcer". These nanoparticles can absorb and disperse external forces, thereby slowing down the deformation and destruction process of the polyurethane matrix; at the same time, the addition of silicone can enable the material to better disperse and withstand stress when subjected to external forces, thereby improving the tensile strength. In addition, the cable material's UV aging resistance is significantly improved. After accelerated aging testing in Example 5, the tensile strength decreased by only 5.52%. This is because the nano-TiO2 has a small particle size and can be evenly dispersed in the polyurethane matrix by chemical grafting as a chain extender. It can both reflect and scatter ultraviolet rays and absorb ultraviolet rays, thereby having a stronger UV barrier ability and forming an effective UV barrier layer. When TiO2 is irradiated with ultraviolet light, its valence band electrons can gain energy and transition to the conduction band, thereby forming photogenerated electrons. The photogenerated electrons are captured by oxygen in the air to generate superoxide radicals, which can oxidize organic pollutants to produce carbon dioxide and water. Therefore, nano-TiO2 has good absorption of ultraviolet light. The absorption and scattering of ultraviolet light constitute a shielding effect against ultraviolet light, reducing the damage of ultraviolet light to the polyurethane material and improving the cable material's UV aging resistance. Comparative Examples 1 and 3 do not contain nano-TiO2 and do not have UV resistance. The nano-TiO2 in Comparative Example 2 is unmodified and easily agglomerates in the polyurethane matrix, resulting in average UV resistance.

[0074] Heat aging resistance test: Notched impact strength test was conducted in accordance with GB / T 1043.1-2008. Heat aging conditions were hot air, 120°C for 24 hours. Impact strength retention was the percentage of the impact strength after aging to the impact strength before aging.

[0075] Table 2 Heat aging resistance test

[0076]

[0077]

[0078] As shown in Table 2 test results, along with diol naphthalene organosilicon modified TiO2 content, the impact strength and the heat aging resistance of cable material strengthen gradually, and wherein the impact strength retention rate of embodiment 4 is 97.76%, this is because the naphthalene ring is a high-rigidity conjugated system, and the π electron cloud distribution is comparatively even, and this makes the naphthalene ring structure relatively stable, and is not susceptible to heat or chemical attack and decomposes, and is introduced in the polyurethane molecular chain, and the regularity and the symmetry of hard segment can be improved, and is not prone to deformation or flow at high temperature, so that it can still keep good mechanical property at high temperature; The bond energy of organosiloxane is larger simultaneously, and thermal decomposition temperature is higher, and heat resistance is better, thereby improved the heat aging resistance of polyurethane.

[0079] Maximum smoke density test: Tested in accordance with GB / T 17651.1-2021 standard.

[0080] Table 3 Flame retardant performance test

[0081] Maximum smoke density (flame method) Example 1 56.6 Example 2 52.3 Example 3 48.1 Example 4 42.5 Example 5 41.4 Comparative Example 1 58.6 Comparative Example 2 59.2 Comparative Example 3 68.7

[0082] The smaller the maximum smoke density, the less smoke the cable produces when it burns, and the smaller the threat to human health and the environment. The test results in Table 3 show that the polyurethane cable material prepared by the present invention has high flame retardant properties and low smoke characteristics. This is because, on the one hand, silicone decomposes under heat during the combustion process to produce inorganic substances such as SiO2. Expanded graphite can rapidly expand hundreds of times at high temperatures to form a fluffy carbonaceous protective layer that can isolate oxygen and heat and prevent the spread of flames. The protective layer formed by silicone is denser and smoother, while the protective layer formed by expanded graphite is more fluffy and porous. The two protective layers are superimposed on each other to form a thicker and more effective flame retardant barrier. After modification, nano-TiO2 can not only promote dispersion and reduce the negative mechanical effects of agglomeration on polyurethane, but also interact with the modified polyurethane to synergistically improve the flame retardant properties of the cable material.

[0083] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing an aging-resistant material for rail transit cables, characterized in that: The preparation method is carried out according to the following steps: Step (1), under a nitrogen atmosphere, vacuum dehydrating 100 parts of polyether polyol by weight at 110-120° C. for 1-3 hours, cooling to 50-65° C., adding 20-30 parts of toluene diisocyanate and 0.5-0.8 parts of dibutyltin dilaurate, reacting at 75-90° C. for 2-5 hours, then adding 2-10 parts of diol naphthalene organosilicon-modified TiO2, continuing the reaction for 0.5-1 hour, adding triethylamine to adjust the pH to 7-8, adding 10-15 parts of dimethylthiotoluene diamine for curing, and obtaining a heat-resistant and aging-resistant polyurethane; Step (2), placing 100 parts of polyurethane and 20-30 parts of heat-resistant and aging-resistant polyurethane in parts by weight in a high-speed kneader, kneading at 100-110° C. for 35-50 minutes, then adding 12-15 parts of expanded graphite and 0.2-0.5 parts of antioxidant, heating to 190-210° C. and kneading for 20-30 minutes, transferring the mixture to an open mill and thinning it 4-6 times, cooling the material, discharging the material, and calendering to obtain an aging-resistant material for rail transit cables; The preparation method of diol naphthalene organosilicon-modified TiO2 in step (1) is carried out according to the following steps: Step S1, under a nitrogen atmosphere, adding methylvinyldichlorosilane and toluene to a reaction flask, stirring evenly, adding 2-hydroxy-6-methoxynaphthalene and sodium hydride, stirring to react, cooling and filtering after the reaction, washing with saturated brine, purifying by column chromatography, and concentrating the organic phase to obtain dimethoxynaphthalene organosilicon; Step S2: under a nitrogen atmosphere, add dimethoxynaphthalene organosilicon and methanol to a reaction flask, stir evenly, add bis[3-(trimethoxysilyl)propyl]amine, react at 45-60° C. for 8-16 hours, and distill under reduced pressure to obtain a dimethoxynaphthalene organosilicon coupling agent; Step S3: Under a nitrogen atmosphere, nano-TiO2, ethanol, and deionized water are added to a reaction flask. After uniform dispersion, dimethoxynaphthalene organosilicon coupling agent is added, the pH of the system is adjusted to 3-5 with glacial acetic acid, ultrasonically reacted at a temperature of 50-70°C and a power of 100-120 Hz for 20-40 minutes, filtered, washed, and dried under reduced pressure, then dispersed in dichloromethane, boron tribromide is added dropwise, reacted at room temperature for 12-24 hours, filtered, and washed with ethanol to obtain diolnaphthalene organosilicon-modified TiO2; In step S1, the molar ratio of methylvinyldichlorosilane, 2-hydroxy-6-methoxynaphthalene, and sodium hydride is 1 mol: (2.05-2.2) mol: (2.3-2.5) mol; In step S2, the molar ratio of dimethoxynaphthalene organosilicon and bis[3-(trimethoxysilyl)propyl]amine is 1 mol:(1.1-1.25) mol; In step S3, the ratio of nano-TiO2, dimethoxynaphthalene organosilicon coupling agent, and boron tribromide is 1g: (0.2-0.4)g: (0.9-1.2)g.

2. The method for preparing the aging-resistant material for rail transit cables according to claim 1, characterized in that: The polyether polyol in step (1) is polycarbonate diol with a molecular weight of 2000.

3. The method for preparing the aging-resistant material for rail transit cables according to claim 1, characterized in that: The antioxidant in step (2) is a mixture of antioxidant 168 and antioxidant 1010 in a mass ratio of 0.5:

1.

4. The method for preparing an aging-resistant material for rail transit cables according to claim 1, characterized in that: In step S1, the reaction temperature is 80-100° C. and the reaction time is 5-10 h.

5. An aging-resistant material for rail transit cables, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 4.

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