Wear-resistant flame-retardant PUR protection tube and preparation method thereof

Abstract

The invention belongs to the technical field of PUR protective sleeves, and particularly relates to a wear-resistant flame-retardant PUR protective tube and a preparation method thereof. The wear-resistant flame-retardant PUR protection tube comprises the following raw materials in parts by weight: 75-80 parts of PUR resin, 4-10 parts of a main flame retardant, 8-12 parts of a DOPO-based fluorine-silicon-phosphorus-nitrogen-containing flame retardant, 1-1.5 parts of a lubricant and 0.8-1 part of an antioxidant.

Description

Technical Field

[0001] The invention belongs to the technical field of PUR protective sleeves, and in particular relates to a wear-resistant and flame-retardant PUR protective tube and a preparation method thereof. Background Art

[0002] With the rapid development of the automobile industry, as vehicle design gradually moves towards lightweight and compactness, the layout of wire harnesses has become increasingly complex, especially in the bottom area of ​​the car, where the wire harnesses face extremely harsh use environments. These wire harnesses may not only be worn due to contact with the ground during vehicle driving, but also be damaged by splashing water droplets, mud and corrosive substances. Therefore, in order to protect the wire harnesses at the bottom of the car, protective sleeves made of various materials are generally used. However, the wire harness protective sleeves commonly used in the prior art still have many limitations in performance and are difficult to fully meet the high requirements of modern cars for wire harness protection.

[0003] At present, the main wire harness protection sleeves on the market include polyurethane (PUR) smooth hoses, polyvinyl chloride (PVC) hoses, and polyamide / polypropylene (PA / PP) corrugated hoses. Among them, PUR smooth hoses are widely used because of their good flexibility and weather resistance, but their smooth surface characteristics make them easy to slip during installation and their fixing performance is insufficient. In addition, in order to improve the hydrolysis resistance of PUR materials, polyether-type PUR raw materials are usually required, but the cost of this material is relatively high, making the overall product less economical. Although PVC hoses have a lower cost, they are not suitable for long-term use under harsh conditions due to their poor temperature resistance, especially in low temperature environments where they become brittle. PA / PP corrugated hoses have better wear resistance and weather resistance, but they are more rigid and less flexible. At the same time, the high processing cost also limits their application range.

[0004] Modification of the flame retardant properties of PUR hoses is also a key direction in existing technologies. However, traditional flame retardant modification usually relies on the addition of halogen flame retardants or inorganic flame retardants. Although these flame retardants can significantly improve the flame retardant properties of materials, they also bring problems that cannot be ignored. For example, halogen flame retardants may release toxic substances during processing and use, posing environmental risks; and high addition of inorganic flame retardants may not only cause powder precipitation on the surface of the material, but also significantly reduce the wear resistance and low-temperature flexibility of PUR pipes, thereby affecting their performance in extreme environments. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned shortcomings and provide a PUR protective hose and a preparation method thereof. By introducing a DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant, not only the flame retardant properties of the material are significantly improved, but also the wear resistance and low-temperature flexibility of the PUR tube are improved, so that it can be used under harsh working conditions.

[0006] A wear-resistant flame-retardant PUR protective tube, the raw materials of which are measured by weight: 75-80 parts of PUR resin, 4-10 parts of main flame retardant, 8-12 parts of DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, 1-1.5 parts of lubricant and 0.8-1 part of antioxidant.

[0007] Furthermore, the PUR resin includes one or more of polyester resin and polyether resin; the hardness of the PUR resin is 75A-50D.

[0008] Furthermore, the main flame retardant includes one or more of halogen flame retardants, phosphorus flame retardants, nitrogen flame retardants, phosphorus-nitrogen flame retardants, and inorganic hydroxides.

[0009] Furthermore, the lubricant includes one or more of paraffin, polyethylene wax, stearic acid, hydroxystearic acid, vinyl bisstearamide, butyl stearate, oleamide, barium stearate, zinc stearate, calcium stearate, cadmium stearate, magnesium stearate, lead stearate, and silicone oil.

[0010] Furthermore, the antioxidant includes one or more of a hindered phenol antioxidant, a phosphite antioxidant and a hindered amine antioxidant.

[0011] Furthermore, the raw materials also include 1 to 1.5 parts of masterbatch by weight.

[0012] A method for preparing a wear-resistant and flame-retardant PUR protective tube comprises the following steps: uniformly mixing PUR resin, a main flame retardant, a DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, a lubricant, an antioxidant and a masterbatch raw material according to parts by weight, and then extruding the mixture into a tube to obtain the wear-resistant and flame-retardant PUR protective tube.

[0013] Furthermore, the preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant comprises the following steps:

[0014] Adding TAIC to molten DOPO in batches, heating and reacting under an inert atmosphere, grinding, washing and drying after cooling to obtain a DOPO-TAIC flame retardant;

[0015] The DOPO flame retardant is added to vinyl fluorosilicone oil, an initiator and a accelerator are added to react, and vacuum degassing is performed at a constant temperature to obtain the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant.

[0016] Furthermore, the preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant specifically comprises the following steps:

[0017] Add TAIC to molten DOPO in batches, heat to 115°C to 125°C and react for 3.5h to 4.5h under an inert atmosphere, cool to room temperature, grind, wash with ethyl acetate, and dry to obtain a DOPO-TAIC flame retardant;

[0018] The vinyl fluorosilicone oil is stirred for 25 to 35 minutes, the DOPO flame retardant is added and stirred for 25 to 35 minutes, an initiator and an accelerator are added to react for 6 to 12 hours, and vacuum degassing is performed at a constant temperature of 115° C. to 125° C. to obtain the DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant.

[0019] Furthermore, the initiator includes cyclohexanone peroxide; and the accelerator includes cobalt octoate.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a wear-resistant and flame-retardant PUR protective tube, which uses PUR resin as the core substrate, and its material properties provide a reliable basic guarantee in terms of mechanical properties, flexibility and durability. Through the synergistic combination of the main flame retardant and the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, not only the flame retardant properties of the material are significantly enhanced, but also the problems of decreased wear resistance and weakened flexibility that may be caused by a single flame retardant system are effectively avoided. In particular, the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant achieves performance stability in high and low temperature environments through its unique molecular structure, and enhances the material's wear resistance, weather resistance and environmental adaptability, so that the protective tube can operate stably for a long time under harsh working conditions. At the same time, the addition of lubricants effectively reduces the friction resistance during extrusion molding while improving the fluidity of the material melt, which not only ensures the stability of the processing process, but also forms a micro-lubricating layer on the surface of the finished product, thereby further improving the wear resistance. The antioxidant improves the material's resistance to thermal oxidation aging, delays the attenuation of performance during use, and ensures the long-term reliability of the protective tube. This optimized raw material ratio and synergistic effect makes the wear-resistant and flame-retardant PUR protective tube have excellent flame-retardant properties while taking into account wear resistance, high strength and excellent processing performance. It becomes an ideal choice to meet the complex protection needs of automotive wiring harnesses and has significant technical value and application prospects. DETAILED DESCRIPTION

[0022] The following examples further describe in detail a wear-resistant, flame-retardant PUR protective tube and a preparation method thereof described in the present invention. For the sake of simplicity of description, this document cannot enumerate all alternative technical features and implementation schemes contained in the present invention. Therefore, those skilled in the art should be aware that any technical features and implementation schemes in this embodiment do not limit the scope of protection of the present invention, which includes any alternative technical features and implementation schemes adopted by all those skilled in the art without creative labor. Specifically, implementation schemes obtained by replacing any technical feature in the present invention or combining any two or more technical features provided by the present invention should be within the scope of protection of the present invention.

[0023] The present embodiment provides a wear-resistant and flame-retardant PUR protective tube. The raw materials, measured in parts by weight, include: 75-80 parts of PUR resin, 4-10 parts of main flame retardant, 8-12 parts of DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, 1-1.5 parts of lubricant and 0.8-1 part of antioxidant.

[0024] In some embodiments, the PUR resin includes one or more of a polyester resin and a polyether resin; and the hardness of the PUR resin is 75A-50D.

[0025] In some embodiments, the main flame retardant includes one or more of a halogen flame retardant, a phosphorus flame retardant, a nitrogen flame retardant, a phosphorus-nitrogen flame retardant, and an inorganic hydroxide.

[0026] In some embodiments, the lubricant includes one or more of paraffin, polyethylene wax, stearic acid, hydroxystearic acid, vinyl bisstearamide, butyl stearate, oleamide, barium stearate, zinc stearate, calcium stearate, cadmium stearate, magnesium stearate, lead stearate, and silicone oil.

[0027] In some embodiments, the antioxidant includes one or more of a hindered phenol antioxidant, a phosphite antioxidant, and a hindered amine antioxidant.

[0028] In some embodiments, the raw materials, by weight, further include 1 to 1.5 parts of masterbatch.

[0029] The present embodiment provides a method for preparing a wear-resistant and flame-retardant PUR protective tube, comprising the following process: mixing PUR resin, main flame retardant, DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, lubricant, antioxidant and masterbatch raw materials in parts by weight and then extruding the mixture into a tube to obtain the wear-resistant and flame-retardant PUR protective tube.

[0030] In some embodiments, the preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant comprises the following steps:

[0031] Adding TAIC to molten DOPO in batches, heating and reacting under an inert atmosphere, grinding, washing and drying after cooling to obtain a DOPO-TAIC flame retardant;

[0032] The DOPO flame retardant is added to vinyl fluorosilicone oil, an initiator and a accelerator are added to react, and vacuum degassing is performed at a constant temperature to obtain the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant.

[0033] In some embodiments, the preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant specifically comprises the following steps:

[0034] Add TAIC to molten DOPO in batches, heat to 115°C to 125°C and react for 3.5h to 4.5h under an inert atmosphere, cool to room temperature, grind, wash with ethyl acetate, and dry to obtain a DOPO-TAIC flame retardant;

[0035] The vinyl fluorosilicone oil is stirred for 25 to 35 minutes, the DOPO flame retardant is added and stirred for 25 to 35 minutes, an initiator and an accelerator are added to react for 6 to 12 hours, and vacuum degassing is performed at a constant temperature of 115° C. to 125° C. to obtain the DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant.

[0036] In some embodiments, the initiator comprises cyclohexanone peroxide; and the accelerator comprises cobalt octoate.

[0037] In the reaction of DOPO and TAIC, the phosphine group of DOPO participates in the reaction through a covalent bond, giving the flame retardant a strong flame retardant function. As a trifunctional monomer, TAIC can undergo a controllable cross-linking polymerization reaction with DOPO by gradual addition under melting conditions of 115°C to 125°C and an inert atmosphere. The reaction ensures sufficient reaction while avoiding the formation of by-products by precisely controlling time and temperature. After cooling, the DOPO-TAIC flame retardant generated by the reaction is ground, washed with ethyl acetate, and vacuum dried to prepare a high-purity powder, which significantly improves subsequent dispersibility and application performance.

[0038] In the subsequent reaction of DOPO-TAIC and vinyl fluorosilicone oil, free radical polymerization was initiated by the initiator cyclohexanone peroxide, and cobalt octanoate was used as a promoter to further accelerate the cross-linking reaction, so that the DOPO-TAIC molecules were successfully grafted to the fluorosilicon-based molecular skeleton. The reaction was carried out at 115℃~125℃ for 6h~12h, and the low molecular by-products were removed by rotary evaporation to generate a fluorine-containing silicon-phosphorus-nitrogen synergistic flame retardant with a highly cross-linked structure. The introduction of fluorosilicon groups in this flame retardant molecule not only gives it excellent thermal stability and chemical inertness, but also enhances its uniform dispersion and interfacial compatibility in the matrix. At the same time, the cross-linked structure of the flame retardant further improves the flame retardant efficiency and shows significant advantages in the low-temperature flexibility and wear resistance of the material.

[0039] The above-mentioned DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant is applied to PUR protective tubes, which gives the material excellent flame retardant properties, and at the same time has a profound optimization effect on the mechanical properties, processing properties and environmental adaptability of the material. Specifically, the flame retardant effectively enhances the high temperature resistance, hydrolysis resistance and weather resistance of the PUR material, and its fluorine-silicon structural characteristics improve the wear resistance and low-temperature bending properties of the protective tube, making it suitable for complex and harsh working conditions. In addition, due to the high compatibility of the flame retardant with the PUR substrate, the powder precipitation phenomenon common in traditional flame retardant systems is significantly reduced, thereby improving the material processing stability and service life, and providing strong technical support for the high performance and reliability of the PUR protective tube.

[0040] Example

[0041] Example 1

[0042] Example 1 provides a wear-resistant and flame-retardant PUR protective tube, the raw materials including: 75kg of PUR resin, 7kg of main flame retardant ADP, 10kg of DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant, 1.3kg of lubricant stearic acid and 0.9kg of antioxidant; wherein the antioxidant is a compound antioxidant of 1076 and 1010 type antioxidants in a mass ratio of 1:1.

[0043] Example 1 also provides a method for preparing a wear-resistant and flame-retardant PUR protective tube, comprising the following steps: mixing the raw materials uniformly by weight and then extruding the raw materials into a tube to obtain a wear-resistant and flame-retardant PUR protective tube.

[0044] Example 1 also provides a method for preparing a DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, comprising the following steps:

[0045] After DOPO was completely melted in a flask under mechanical stirring at 100°C, TAIC was slowly added to the reaction system in 10 portions, the temperature was raised to 120°C, and the mixture was stirred and reacted for 4 hours under a nitrogen protection environment. After the reaction was completed, the product was ground at room temperature and washed with a large amount of ethyl acetate, filtered, and vacuum dried at 60°C for 5 hours to obtain a DOPO-TAIC flame retardant;

[0046] A certain amount of vinyl fluorosilicone oil (Xinyuan Chemical, NFS7000 series, vinyl content 0.01% ~ 16.0%) was added to a three-necked flask and mechanically stirred for 30 minutes. DOPO-TAIC flame retardant was added and stirred for 30 minutes. Then, the initiator cyclohexanone peroxide was added and stirred evenly. Then, 1 g of accelerator cobalt octanoate was added and reacted for 6 hours. The temperature of the reaction product was maintained at 120 ° C and vacuum evaporated using a rotary evaporator until there was no fraction to obtain a DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant.

[0047] Example 2

[0048] Example 2 provides a wear-resistant and flame-retardant PUR protective tube, the raw materials including: 80 kg of PUR resin, 10 kg of main flame retardant ADP, 12 kg of DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant, 1.5 kg of lubricant stearic acid and 1 kg of antioxidant; wherein the antioxidant is a compound antioxidant of 1076 and 1010 type antioxidants in a mass ratio of 1:1.

[0049] Example 2 also provides a method for preparing a wear-resistant and flame-retardant PUR protective tube, comprising the following steps: mixing the raw materials uniformly by weight and then extruding the raw materials into a tube to obtain a wear-resistant and flame-retardant PUR protective tube.

[0050] Example 2 also provides a method for preparing a DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, comprising the following steps:

[0051] After DOPO was completely melted in a flask under mechanical stirring at 100°C, TAIC was slowly added to the reaction system in 10 portions, the temperature was raised to 115°C, and the mixture was stirred and reacted for 4.5 hours under a nitrogen protection environment. After the reaction was completed, the product was ground at room temperature and washed with a large amount of ethyl acetate, filtered, and vacuum dried at 60°C for 5 hours to obtain a DOPO-TAIC flame retardant;

[0052] A certain amount of vinyl fluorosilicone oil (Xinyuan Chemical, NFS7000 series, vinyl content 0.01% ~ 16.0%) was added to a three-necked flask and mechanically stirred for 35 minutes. DOPO-TAIC flame retardant was added and stirred for 35 minutes. Then, the initiator cyclohexanone peroxide was added and stirred evenly. Then, 1 g of accelerator cobalt octanoate was added and reacted for 12 hours. The temperature of the reaction product was maintained at 120 ° C and vacuum evaporated using a rotary evaporator until there was no fraction to obtain a DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant.

[0053] Example 3

[0054] Example 3 provides a wear-resistant and flame-retardant PUR protective tube, the raw materials including: 75kg of PUR resin, 4kg of main flame retardant ADP, 8kg of DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant, 1kg of lubricant stearic acid and 0.8kg of antioxidant; wherein the antioxidant is a compound antioxidant of 1076 and 1010 type antioxidants in a mass ratio of 1:1.

[0055] Example 3 also provides a method for preparing a wear-resistant and flame-retardant PUR protective tube, comprising the following steps: mixing the raw materials uniformly by weight and then extruding the raw materials into a tube to obtain a wear-resistant and flame-retardant PUR protective tube.

[0056] Example 3 also provides a method for preparing a DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, comprising the following steps:

[0057] After DOPO was completely melted in a flask under mechanical stirring at 100°C, TAIC was slowly added to the reaction system in 10 portions, the temperature was raised to 125°C, and the mixture was stirred for reaction for 3.5 hours under nitrogen protection. After the reaction was completed, the product was ground at room temperature and washed with a large amount of ethyl acetate, filtered, and vacuum dried at 60°C for 5 hours to obtain DOPO-TAIC flame retardant;

[0058] A certain amount of vinyl fluorosilicone oil (Xinyuan Chemical, NFS7000 series, vinyl content 0.01% ~ 16.0%) was added to a three-necked flask and mechanically stirred for 25 minutes. DOPO-TAIC flame retardant was added and stirred for 25 minutes. Then, the initiator cyclohexanone peroxide was added and stirred evenly. Then, 1 g of accelerator cobalt octanoate was added and reacted for 8 hours. The temperature of the reaction product was maintained at 120 ° C and vacuum evaporated using a rotary evaporator until there was no fraction to obtain a DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant.

[0059] Example 4

[0060] Example 4 provides a wear-resistant and flame-retardant PUR protective tube, which is different from Example 1 in that the raw materials also include 1 kg of masterbatch.

[0061] The preparation method of the wear-resistant flame-retardant PUR protective tube and the preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant provided in Example 4 are the same as those in Example 1.

[0062] Comparative Example

[0063] Comparative Example 1

[0064] Comparative Example 1 provides a wear-resistant flame-retardant PUR protective tube. The difference from Example 1 is that the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant is replaced by the main flame retardant ADP in equal amounts, as follows:

[0065] Comparative Example 1 provides a wear-resistant and flame-retardant PUR protective tube, the raw materials of which include: 75 kg of PUR resin, 17 kg of main flame retardant ADP, 1.3 kg of lubricant stearic acid and 0.9 kg of antioxidant; wherein the antioxidant is a compound antioxidant of 1076 and 1010 type antioxidants in a mass ratio of 1:1.

[0066] The preparation method of the wear-resistant and flame-retardant PUR protective tube provided in Comparative Example 1 is the same as that in Example 1.

[0067] Comparative Example 2

[0068] Comparative Example 2 provides a wear-resistant flame-retardant PUR protective tube. The difference from Example 1 is that the main flame retardant ADP is replaced by a DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant in equal amounts, as follows:

[0069] Comparative Example 2 provides a wear-resistant and flame-retardant PUR protective tube, the raw materials of which include: 75 kg of PUR resin, 17 kg of DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, 1.3 kg of lubricant stearic acid and 0.9 kg of antioxidant; wherein the antioxidant is a compound antioxidant of 1076 and 1010 type antioxidants in a mass ratio of 1:1.

[0070] The preparation method of the wear-resistant flame-retardant PUR protective tube and the preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant provided in Comparative Example 2 are the same as those in Example 1.

[0071] Comparative Example 3

[0072] Comparative Example 3 provides a wear-resistant flame-retardant PUR protective tube. The difference from Example 1 is that the main flame retardant ADP and DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant are replaced by PUR resin in equal amounts, as follows:

[0073] Comparative Example 3 provides a wear-resistant and flame-retardant PUR protective tube, the raw materials of which include: 92 kg of PUR resin, 1.3 kg of lubricant stearic acid and 0.9 kg of antioxidant; wherein the antioxidant is a compound antioxidant of 1076 and 1010 type antioxidants in a mass ratio of 1:1.

[0074] The preparation method of the wear-resistant and flame-retardant PUR protective tube provided in Comparative Example 3 is the same as that in Example 1.

[0075] Performance Testing

[0076] The wear-resistant flame-retardant PUR protective tubes provided in Examples 1-4 and Comparative Examples 1-3 were tested for mechanical properties and wear resistance. The specific test methods are as follows:

[0077] Refer to the requirements of Section 6.3.3 of MBN_LV_312-3_2017-09, use the finished product test, and perform the following method conditions: Test conditions: sample length: 100mm; test rate: 100mm / min; fixture distance: 50mm; observe the surface of the extruded tube of each formula and record whether the frosting is good or not.

[0078] Wear resistance test is in accordance with ISO 6722-1:2011 Section 5.12.4.2. Product pretreatment conditions: 23℃±5℃, 45~75%RH, 16h; Test conditions: Test frequency: (55±5) cycles / min; Test load: 7N, Grinding needle diameter: 0.45mm±0.01mm; Wear length: 20mm±1mm; Grinding needle length: 15.5mm±1mm; Grinding needle replacement frequency: 1 time / pcs; Mandrel specification: Φ9mm.

[0079] The test results of the mechanical properties and wear resistance of the PUR protective hoses provided in the examples and comparative examples are shown in Table 1.

[0080] Table 1 Mechanical properties and wear resistance of PUR protective tubes provided in Examples 1-4 and Comparative Examples 1-3

[0081]

[0082] The mechanical properties and wear resistance test results of Examples 1-4 and Comparative Examples 1-3 clearly reflect the significant differences in the mechanical strength, flexibility and wear resistance of the materials. The tensile force of Example 1 reached 29.4MPa, the elongation was 500%, and the number of wear resistance was as high as 61821 times, showing excellent mechanical strength, flexibility and wear resistance. This result shows that by introducing DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant, the material not only has excellent flame retardant properties, but also shows significant improvement in mechanical properties and service life, and is suitable for long-term applications under high load and complex working conditions.

[0083] The mechanical properties of Comparative Examples 1-3 are significantly poorer, and the tensile force gradually decreases, among which Comparative Example 3 is only 20.8 MPa, the elongation drops to 430%, and the wear times are only 50030 times, which is much lower than Example 1. Especially under long-term wear conditions, the material of Comparative Example 3 shows obvious fatigue damage and performance attenuation, and cannot meet the requirements of high strength and high wear resistance in practical applications.

[0084] From the perspective of overall performance, Example 1 successfully achieved a balance between flame retardancy and mechanical properties through precise optimization of the formula design, and the tensile strength, elongation and wear resistance all reached the industry-leading level.

[0085] Flame retardant performance test

[0086] The PUR protective tubes provided in Examples 1-4 and Comparative Examples 1-3 were subjected to the following flame retardant performance tests, as follows:

[0087] 1. Limiting Oxygen Index (LOI)

[0088] Test Method

[0089] The oxygen index test is conducted according to ASTM D2863. The test uses a mixed gas of oxygen and nitrogen to adjust the oxygen concentration to determine the minimum oxygen content at which the material can maintain stable combustion. The experimental steps are as follows:

[0090] Prepare standard size specimens (length 70 mm, width 6.5 mm, thickness 3 mm);

[0091] Fix the sample vertically in the combustion chamber inside the LOI instrument;

[0092] Ignite the sample from the bottom, gradually adjust the oxygen concentration, and observe whether the sample can maintain stable combustion;

[0093] Record the minimum oxygen volume fraction required for combustion.

[0094] 2. UL-94 vertical burning rating

[0095] Test Method

[0096] The UL-94 test is based on the UL 94 standard and evaluates the self-extinguishing ability and dripping of materials after combustion. It is divided into horizontal combustion (HB) and vertical combustion (V-0, V-1, V-2) levels, with V-0 being the highest flame retardant level.

[0097] Test steps:

[0098] Prepare the specimen (125 mm × 13 mm × 3 mm);

[0099] Fix the sample vertically and ignite the bottom of the sample for 10 seconds;

[0100] Record the time when the flame goes out and observe whether the molten droplets ignite the cotton at the bottom;

[0101] Repeat the burning twice and determine the grade according to the standard.

[0102] 3. Heat Release Rate (HRR)

[0103] Test Method

[0104] HRR is tested by Cone Calorimeter according to ISO 5660-1 standard: The experimental steps are as follows:

[0105] Prepare the specimen (100 mm × 100 mm × 3 mm);

[0106] In a cone calorimeter at 35 kW / m 2 Ignite the sample under thermal radiation conditions;

[0107] The peak amount of heat released per unit time during the combustion of the test material.

[0108] 4. Total Heat Release (THR)

[0109] Test Method

[0110] THR and HRR tests are carried out simultaneously, indicating the total heat released by the sample during combustion, which is obtained by integrating the heat release rate curve.

[0111] 5. Smoke Density Rating (SDR)

[0112] Test Method

[0113] The smoke density test is based on the ASTM E662 standard to determine the smoke density generated when the material burns. The specific steps are as follows:

[0114] Prepare the specimen (75 mm × 75 mm × 3 mm);

[0115] The changes in smoke transmittance were recorded by an optical measuring device in a closed combustion box;

[0116] Calculate the maximum smoke density (Ds value).

[0117] 6. Thermal decomposition behavior

[0118] Test Method

[0119] The thermal stability and thermal decomposition behavior of the material were tested by thermogravimetric analyzer (TGA) according to ISO 11358 standard: The specific steps are as follows:

[0120] Under nitrogen protection, the heating rate was 10℃ / min, and the test temperature range was 30℃~800℃;

[0121] The initial decomposition temperature (T0), maximum decomposition rate temperature (Tmax) and carbon residue rate were recorded.

[0122] The flame retardant performance test results of the wear-resistant flame retardant PUR protective tubes provided by Examples 1-4 and Comparative Examples 1-3 are shown in Table 2 below.

[0123] Table 2 Flame retardant properties of PUR protective tubes provided by Examples 1-4 and Comparative Examples 1-3

[0124]

[0125] As can be seen from Table 2, the difference in flame retardant properties between Examples 1-4 and Comparative Examples 1-3 fully verifies the scientific nature of the formula design and the significance of the synergistic flame retardant effect. The oxygen index (LOI) of Example 1 reaches 33.5%, which is the highest among all samples, far exceeding the comparative examples, especially Comparative Example 3, which is only 24.0%, indicating that the material of Example 1 has a stronger flame retardant ability in an oxygen environment. In addition, the UL-94 vertical combustion test results show that Example 1 reaches the V-0 level, the flame extinguishing time is only 2 seconds, and no molten droplets appear, and the combustion self-extinguishing property and safety performance are excellent, while the level of Comparative Example 3 is only V-2, the extinguishing time is as long as 20 seconds, accompanied by the phenomenon of molten droplet ignition, which obviously cannot meet the high flame retardant requirements.

[0126] In terms of heat release rate (HRR) and total heat release (THR), Example 1 exhibited excellent combustion suppression characteristics, with an HRR of 185 kW / m 2 , THR is 15.8MJ / m 2 , are the lowest values, indicating that the material releases less energy when burning, effectively reducing the fire load and spread risk. In contrast, the HRR of comparative example 3 is as high as 320kW / m 2 ,THR is 26.5MJ / m 2 , indicating that it releases a large amount of heat in a fire, has a high combustion intensity, and is significantly more dangerous. In addition, the smoke density (SDR) test further shows that the smoke density of Example 1 is only 30, and very little smoke is generated during the combustion process, which is conducive to improving the safety in a fire environment, while the smoke density of Comparative Example 3 is as high as 60, and a large amount of smoke is generated during combustion, further exacerbating safety hazards.

[0127] From the perspective of thermal decomposition behavior, the initial decomposition temperature (T0) of Example 1 is 310°C, the maximum decomposition rate temperature (Tmax) reaches 430°C, and the residual carbon rate is as high as 18%, showing excellent thermal stability and carbonization protection capabilities. The formation of the carbonized layer can not only effectively isolate oxygen and heat, but also greatly reduce the sustained combustion rate of the material. In contrast, the T0 of Comparative Example 3 is 250°C, Tmax is 380°C, and the residual carbon rate is only 8%. The thermal decomposition rate of the material is accelerated under high temperature conditions, and the carbonized layer structure is sparse and cannot be effectively flame retardant, which further verifies the lack of thermal stability and flame retardant effect of the material.

[0128] In summary, Example 1 exhibits optimal performance in key indicators such as oxygen index, UL-94 rating, heat release rate, smoke density, and thermal decomposition behavior, verifying the synergistic flame retardant effect and thermal stability of the DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant, successfully solving the problem of easy precipitation and limited flame retardant effect of traditional flame retardants, and providing technical support for high-performance flame-retardant PUR protective tubes.

[0129] For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived from them are still within the scope of protection of the claims of the invention.

Claims

1. A wear-resistant and flame-retardant PUR protective tube, characterized in that: The raw materials include, by weight, 75-80 parts of PUR resin, 4-10 parts of main flame retardant, 8-12 parts of DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, 1-1.5 parts of lubricant and 0.8-1 part of antioxidant.

2. The wear-resistant and flame-retardant PUR protective tube according to claim 1, characterized in that: The PUR resin includes one or more of polyester resin and polyether resin; the hardness of the PUR resin is 75A-50D.

3. The wear-resistant and flame-retardant PUR protective tube according to claim 1, characterized in that: The main flame retardant includes one or more of halogen flame retardant, phosphorus flame retardant, nitrogen flame retardant, phosphorus nitrogen flame retardant and inorganic hydroxide.

4. The wear-resistant and flame-retardant PUR protective tube according to claim 1, characterized in that: The lubricant includes one or more of paraffin, polyethylene wax, stearic acid, hydroxystearic acid, vinyl bisstearamide, butyl stearate, oleamide, barium stearate, zinc stearate, calcium stearate, cadmium stearate, magnesium stearate, lead stearate, and silicone oil.

5. The wear-resistant and flame-retardant PUR protective tube according to claim 1, characterized in that: The antioxidant includes one or more of a hindered phenol antioxidant, a phosphite antioxidant and a hindered amine antioxidant.

6. The wear-resistant and flame-retardant PUR protective tube according to claim 1, characterized in that: The raw materials are calculated by weight and also include 1 to 1.5 parts of masterbatch.

7. A method for preparing the wear-resistant and flame-retardant PUR protective tube according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: uniformly mixing PUR resin, main flame retardant, DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant, lubricant, antioxidant and masterbatch raw materials according to weight proportions and then extruding the mixture into a tube to obtain the wear-resistant flame-retardant PUR protective tube.

8. The method for preparing a wear-resistant and flame-retardant PUR protective tube according to claim 7, characterized in that: The preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant comprises the following steps: Adding TAIC to molten DOPO in batches, heating and reacting under an inert atmosphere, grinding, washing and drying after cooling to obtain a DOPO-TAIC flame retardant; The DOPO flame retardant is added to vinyl fluorosilicone oil, an initiator and a accelerator are added to react, and vacuum degassing is performed at a constant temperature to obtain the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant.

9. The method for preparing a wear-resistant and flame-retardant PUR protective tube according to claim 7, characterized in that: The preparation method of the DOPO-based fluorine-containing silicon-phosphorus-nitrogen flame retardant specifically comprises the following steps: Add TAIC to molten DOPO in batches, heat to 115°C to 125°C and react for 3.5h to 4.5h under an inert atmosphere, cool to room temperature, grind, wash with ethyl acetate, and dry to obtain a DOPO-TAIC flame retardant; The vinyl fluorosilicone oil is stirred for 25 to 35 minutes, the DOPO flame retardant is added and stirred for 25 to 35 minutes, an initiator and an accelerator are added to react for 6 to 12 hours, and vacuum degassing is performed at a constant temperature of 115° C. to 125° C. to obtain the DOPO-based fluorine-containing silicon phosphorus nitrogen flame retardant.

10. The method for preparing a wear-resistant and flame-retardant PUR protective tube according to claim 9, characterized in that: The initiator includes cyclohexanone peroxide; and the accelerator includes cobalt octoate.

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