High-temperature-resistant flame-retardant composite HDPE pipe and preparation method thereof

Abstract

The application relates to the field of plastic pipe manufacturing, and particularly discloses a high-temperature-resistant and flame-retardant composite HDPE pipe and a preparation method thereof.A high-temperature-resistant and flame-retardant composite HDPE pipe, according to weight parts, raw materials include 40-45 parts of polyethylene, 0.5-1 part of a lubricant, 6-7.6 parts of a filler, 2.4-4 parts of a composite flame retardant, 1-3 parts of a heat-stable reinforcing agent and 1.5-2.5 parts of a compatibilizer; the composite flame retardant includes (3-5):(1-2):(0.4-1) decabromodiphenyl ethane, diantimony trioxide and brominated polystyrene; and the filler is calcium carbonate.The high-temperature-resistant and flame-retardant composite HDPE pipe can be used for preparing electric wires and cables, has excellent high-temperature resistance and flame-retardant performance, and can meet the standard requirements of safety and flame-retardant high-temperature resistance in the application of electric wires and cables.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of plastic pipe manufacturing, in particular to a high-temperature-resistant flame-retardant composite HDPE pipe and a preparation method thereof. BACKGROUND

[0002] Plastic pipes have the characteristics of light weight, corrosion resistance and easy processing, and have been widely used in the field of cable protection. However, plastic materials are flammable by nature, and can easily burn and release toxic gases when exposed to high temperatures or open flames. Existing plastic pipes mainly improve their high-temperature resistance and flame retardance by adding flame retardants to the raw materials. Common flame retardants include halogen-based, phosphorus-based and nitrogen-based flame retardants.

[0003] For the related technologies in the above, the inventors found that the existing flame retardants have some problems in use, such as halogen-based flame retardants may produce toxic gases during combustion, which poses a potential threat to the environment and human health; while phosphorus-based and nitrogen-based flame retardants have better environmental friendliness, but their flame retardant efficiency is relatively low, and a high addition amount is often required to achieve the desired flame retardant effect, which to some extent sacrifices the physical properties of the plastic material itself.

[0004] With the rapid development of science and technology and modern industry, higher standards are required for the high-temperature resistance and flame retardance of plastic pipes, especially when used in fields such as power, aerospace and automobile manufacturing that require work in high-temperature environments. The plastic pipes prepared by traditional flame retardant methods cannot meet the standard requirements for high-temperature resistance and flame retardance when used in special fields. SUMMARY

[0005] In order to improve the high-temperature resistance and flame retardance of plastic pipes and ensure the safety of plastic pipes when used in wire and cable protection, the application provides a high-temperature-resistant flame-retardant composite HDPE pipe and a preparation method thereof.

[0006] In a first aspect, the application provides a high-temperature-resistant flame-retardant composite HDPE pipe, which adopts the following technical solution:

[0007] A high-temperature-resistant flame-retardant composite HDPE pipe, according to weight parts, the raw materials include 40-45 parts of polyethylene, 0.5-1 parts of lubricant, 6-7.6 parts of filler, 2.4-4 parts of composite flame retardant, 1-3 parts of heat-stable reinforcing agent and 1.5-2.5 parts of compatibilizer.

[0008] The composite flame retardant includes (3-5):(1-2):(0.4-1) decabromodiphenyl ethane, antimony trioxide and brominated polystyrene; and the filler is calcium carbonate.

[0009] By adopting the technical scheme, the inventor finds that the flame-retardant effect of antimony trioxide alone is poor, antimony trioxide, decabromodiphenyl ethane and brominated polystyrene are mixed as flame retardants, bromodiphenyl ethane and brominated polystyrene are decomposed by heat reaction to release hydrogen halide and halogen elements, the two substances have high activity and can react with antimony trioxide to produce antimony trihalide and oxyhalide, interfere with the combustion chain reaction, and significantly improve the flame retardancy of the material.

[0010] Antimony trihalide can react with high polymer to make the high polymer tend to generate carbon layer instead of flammable gas when heated. The carbon layer forms a stable barrier on the surface of the material, isolating heat and oxygen, thereby protecting the underlying high polymer from further thermal decomposition and combustion, limiting the thermal decomposition of the high polymer, and further reducing the generation of flammable gas.

[0011] In addition, in the reaction process of antimony trioxide and halogen compounds, in addition to the generation of antimony trihalide and oxyhalide, inert gases such as bromine gas (Br2) generated by the decomposition of hydrogen bromide (HBr) are also generated. These inert gases dilute the concentration of oxygen in the flame, reducing the oxygen supply required for combustion, thereby inhibiting the combustion process.

[0012] Calcium carbonate as a filler can enhance the dimensional stability of the pipe and improve the dispersion uniformity of the overall powder.

[0013] Optionally, the calcium carbonate is talc and nano active calcium carbonate with a mass ratio of (1-3):1.

[0014] By adopting the technical scheme, talc can form a stable ceramic layer when heated, which can isolate heat and oxygen, reduce the burning rate of the material, and nano active calcium carbonate has a high specific surface area and can be more uniformly dispersed in the polyethylene pipe matrix, which can promote the formation of carbon layer and further enhance the flame retardant effect.

[0015] In addition, talc has excellent thermal stability, and nano active calcium carbonate can absorb heat when decomposed at high temperature, which helps to reduce the temperature of the material surface and reduce the thermal decomposition and thermal expansion of the polyethylene pipe at high temperature, which helps to maintain the dimensional stability of the polyethylene pipe.

[0016] Optionally, the thermal stability enhancer is a modified carbon fiber.

[0017] By adopting the technical scheme, the modified carbon fiber has excellent high-temperature resistance and mechanical properties, which helps to improve the thermal stability and mechanical strength of the polyethylene pipe as a thermal stability enhancer, reduces the decrease of the mechanical properties of the polyethylene pipe caused by the addition of inorganic materials, and ensures that the polyethylene pipe maintains excellent application performance at high temperature.

[0018] Optionally, the preparation method of the modified carbon fiber comprises the following steps:

[0019] S1: washing and drying the carbon fiber to remove surface impurities;

[0020] S2: soaking the carbon fiber treated in step S1 in a fatty alcohol ether phosphate potassium salt solution for 1-2 hours, the concentration of the fatty alcohol ether phosphate potassium salt solution is 1.5-2.5%, and after filtration and drying at 100-110°C for 2-4 hours, the modified carbon fiber is obtained.

[0021] By adopting the above technical solution, the soaking treatment of the fatty alcohol ether phosphate potassium salt solution can effectively improve the surface properties of the carbon fiber, reduce the agglomeration of the carbon fiber, and enhance the bonding ability of the carbon fiber with the polyethylene matrix and the dispersibility in the matrix.

[0022] In addition, the fatty alcohol ether phosphate salt introduces a phosphorus-containing functional group on the surface of the carbon fiber, which may decompose at high temperature to produce phosphoric acid or other phosphorus-containing compounds, which helps the polymer surface to quickly dehydrate and carbonize to form a carbonized layer, further hindering the spread of the flame, and improving the overall flame retardant effect.

[0023] Optionally, the lubricant is selected from any one or a combination of more than one of calcium stearate, zinc stearate, barium stearate, and paraffin wax.

[0024] By adopting the above technical solution, calcium stearate, zinc stearate, barium stearate, and paraffin wax as lubricants can all reduce the frictional resistance of the raw materials during processing, improve the processing fluidity and uniformity. At the same time, they also help the pipe to be demolded in the mold, reducing defects and the rate of defective products.

[0025] Optionally, the compatibilizer is selected from any one of PP-g-MAH or EAA.

[0026] By adopting the above technical solution, PP-g-MAH and EAA can improve the interfacial bonding between the polyethylene matrix and other additives, improving the processing performance and overall mechanical properties of the polyethylene pipe.

[0027] In a second aspect, the present application provides a preparation method of a high-temperature-resistant and flame-retardant composite HDPE pipe, which adopts the following technical solution:

[0028] A preparation method of a high-temperature-resistant and flame-retardant composite HDPE pipe comprises the following steps:

[0029] The weight parts of each raw material are weighed according to the weight parts of the raw materials, and all the raw materials are first hot mixed at 100-110°C, and then cold mixed at 30-40°C to obtain a blend;

[0030] The blend is sent into a screw extruder for extrusion molding, vacuum cooling and sizing after extrusion through a die, and the polyethylene pipe material is obtained.

[0031] By adopting the technical scheme, in the hot mixing process, the interaction between the raw material particles is enhanced due to the temperature rise, which helps the uniform dispersion of various additives and fillers in the base resin, can significantly improve the processing fluidity and uniformity of the material, and the cold mixing helps to further ensure that the mixed material after dispersion remains uniform and prevents re-agglomeration caused by temperature change. After the combination of hot mixing and cold mixing, the extrusion molding process in the screw extruder can shorten the mixing cycle, improve the production efficiency and ensure the overall performance of the polyethylene pipe material.

[0032] Optionally, the processing technology of the screw extruder is as follows:

[0033] The feeding screw rotation speed is 40-60 r / min, and the main screw rotation speed is 300-500 r / min.

[0034] The temperature of the first to third zones is 190-220 DEG C, the temperature of the fourth to sixth zones is 230-250 DEG C, and the temperature of the seventh to ninth zones is 200-230 DEG C.

[0035] In summary, the present application has the following beneficial effects:

[0036] 1. Since the present application uses antimony trioxide and decabromodiphenyl ethane, brominated polystyrene as a composite flame retardant, the brominated diphenyl ethane and the brominated polystyrene are decomposed by heat to release hydrogen halide and halogen elements, which can react with antimony trioxide to further produce antimony trihalide, antimony oxyhalide and inert gas, and the antimony trihalide can further react with the polymer to promote the formation of carbon layer, effectively interfering with the combustion chain reaction, and significantly improving the flame retardancy of the material.

[0037] 2. In the present application, talc and nano active calcium carbonate are preferably used as fillers, which can improve the dispersion uniformity of the overall raw materials, and help to maintain the size and structural stability of the polyethylene pipe material at high temperature, and improve the high temperature resistance of the polyethylene pipe material.

[0038] 3. The modified carbon fiber treated with fatty alcohol ether phosphate potassium salt in the present application can effectively improve the dispersion uniformity of the carbon fiber in the polyethylene matrix, ensure the high temperature resistance and overall mechanical properties of the polyethylene pipe material, and on the other hand, introduce phosphorus-containing functional groups, which may produce phosphoric acid or other phosphorus-containing compounds at high temperature, promote the rapid dehydration of the polymer surface to carbon, and further enhance the flame retardant effect. DETAILED DESCRIPTION

[0039] The following examples further illustrate the present application.

[0040] Raw materials

[0041] The raw materials used in the examples and comparative examples in the present application are commercially available products, specifically:

[0042] Polyethylene, selected from Shengli Oilfield, HDPE DMDA-8008H;

[0043] Decabromodiphenyl ethane, selected from Shandong Maofa, MF-11-13;

[0044] Brominated polystyrene, selected from Delin New Materials, XZ-6700;

[0045] Talc, selected from Guanting, GT-123;

[0046] Nano active calcium carbonate, selected from Lei Fu, LF-NMG, 15000 mesh;

[0047] Carbon fiber, single filament diameter 7-10 μm, aspect ratio 1:(50-100);

[0048] Fatty alcohol ether phosphate potassium salt, selected from Jie Nu Chemical Industry, NP-10PK-80;

[0049] Paraffin wax, selected from Qilin Chemical Industry, 58#;

[0050] PP-g-MAH, selected from Dow Dupont, 50E806;

[0051] EAA, selected from Dow Dupont, A560.

[0052] Preparation example of modified carbon fiber

[0053] Preparation example 1

[0054] Modified carbon fiber, its preparation method, comprising the following steps:

[0055] S1: Place the carbon fiber in a Soxhlet extractor, extract the organic impurities on the surface of the carbon fiber with acetone solution for 1.5 h, then wash with deionized water for 3 times, and then dry in an oven at 80°C for 2 h;

[0056] S2: The carbon fiber treated in step S1 is placed in a fatty alcohol ether phosphate potassium salt solution according to the solid-liquid ratio of 1:80 for 1 h, the concentration of the fatty alcohol ether phosphate potassium salt solution is 1.5%, and then filtered and dried in an oven at 100°C for 4 h.

[0057] Preparation example 2

[0058] Modified carbon fiber, its preparation method, comprising the following steps:

[0059] S1: The carbon fiber is placed in a Soxhlet extractor, and organic impurities on the surface of the carbon fiber are removed by extracting with an acetone solution for 1.5 h, and then washed with deionized water for 3 times, and then dried in an oven at 80°C for 2 h.

[0060] S2: The carbon fiber treated in step S1 is placed in a fatty alcohol ether phosphate potassium salt solution according to a solid-liquid ratio of 1:80 for immersion treatment for 1.5 h, and the concentration of the fatty alcohol ether phosphate potassium salt solution is 2%, and then dried in an oven at 100°C for 3 h after filtration.

[0061] Preparation Example 3

[0062] A modified carbon fiber, a preparation method thereof, comprising the following steps:

[0063] S1: The carbon fiber is placed in a Soxhlet extractor, and organic impurities on the surface of the carbon fiber are removed by extracting with an acetone solution for 1.5 h, and then washed with deionized water for 3 times, and then dried in an oven at 80°C for 2 h.

[0064] S2: The carbon fiber treated in step S1 is placed in a fatty alcohol ether phosphate potassium salt solution according to a solid-liquid ratio of 1:80 for immersion treatment for 2 h, and the concentration of the fatty alcohol ether phosphate potassium salt solution is 2.5%, and then dried in an oven at 110°C for 2 h after filtration.

[0065] Preparation Example 4

[0066] A modified carbon fiber, a preparation method thereof, comprising the following steps:

[0067] The carbon fiber is placed in a Soxhlet extractor, and organic impurities on the surface of the carbon fiber are removed by extracting with an acetone solution for 1.5 h, and then washed with deionized water for 3 times, and then dried in an oven at 80°C for 2 h. Example Example 1

[0068] A high-temperature-resistant flame-retardant composite HDPE pipe material, the amounts of various raw materials are shown in Table 1, wherein the lubricant is calcium stearate, the filler is nano active calcium carbonate, the thermal stabilizing type reinforcing agent is the modified carbon fiber obtained in Preparation Example 1, and the compatibilizer is PP-g-MAH.

[0069] Table 1

[0070]

[0071] A preparation method of the above-mentioned high-temperature-resistant flame-retardant composite HDPE pipe material, comprising the following steps:

[0072] S1: The amounts of various raw materials are weighed according to the weight parts of the raw materials, and all the raw materials are first heat-mixed in a heat mixer at 100°C, and then cold-mixed in a cold mixer at 25°C to obtain a blend.

[0073] S2: The blend is sent into a screw extruder for extrusion molding, the feeding screw rotation speed is set to 50 r / min, the main screw rotation speed is set to 500 r / min, the temperature of the first to third zones is 190℃, the temperature of the fourth to sixth zones is 230℃, the temperature of the seventh to ninth zones is 200℃, and after extrusion through a die, vacuum cooling and sizing are performed, and the high-temperature resistant flame-retardant composite HDPE pipe is obtained. Example 2

[0074] A high-temperature resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the raw materials and their amounts are shown in Table 1, wherein the lubricant is zinc stearate;

[0075] The preparation method of the high-temperature resistant flame-retardant composite HDPE pipe, which comprises the following steps:

[0076] S1: The raw materials are weighed according to the weight parts of the raw materials, and all the raw materials are first hot mixed in a hot mixer at 110℃, and then cold mixed in a cold mixer at 35℃ to obtain a blend;

[0077] S2: The blend is sent into a screw extruder for extrusion molding, the feeding screw rotation speed is set to 50 r / min, the main screw rotation speed is set to 400 r / min, the temperature of the first to third zones is 200℃, the temperature of the fourth to sixth zones is 230℃, the temperature of the seventh to ninth zones is 200℃, and after extrusion through a die, vacuum cooling and sizing are performed, and the high-temperature resistant flame-retardant composite HDPE pipe is obtained. Example 3

[0078] A high-temperature resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the raw materials and their amounts are shown in Table 1, wherein the lubricant is barium stearate, and the compatibilizer is EAA;

[0079] The preparation method of the high-temperature resistant flame-retardant composite HDPE pipe, which comprises the following steps:

[0080] S1: The raw materials are weighed according to the weight parts of the raw materials, and all the raw materials are first hot mixed in a hot mixer at 100℃, and then cold mixed in a cold mixer at 30℃ to obtain a blend;

[0081] S2: The blend is sent into a screw extruder for extrusion molding, the feeding screw rotation speed is set to 60 r / min, the main screw rotation speed is set to 500 r / min, the temperature of the first to third zones is 220℃, the temperature of the fourth to sixth zones is 250℃, the temperature of the seventh to ninth zones is 230℃, and after extrusion through a die, vacuum cooling and sizing are performed, and the high-temperature resistant flame-retardant composite HDPE pipe is obtained. Example 4

[0082] A high-temperature resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the raw materials and their amounts are shown in Table 1, wherein the lubricant is paraffin;

[0083] The preparation method of the high-temperature-resistant and flame-retardant composite HDPE pipe material comprises the following steps:

[0084] S1: The raw materials are weighed according to the weight parts of the raw materials, and all the raw materials are first hot mixed in a 110℃ hot mixer and then cold mixed in a 30℃ cold mixer to obtain a blend;

[0085] S2: The blend is sent into a screw extruder for extrusion molding, the feeding screw rotation speed is set to 40r / min, the main screw rotation speed is set to 300r / min, the temperature of the first to third zones is set to 200℃, the temperature of the fourth to sixth zones is set to 240℃, and the temperature of the seventh to ninth zones is set to 210℃, and after extrusion through a mold, vacuum cooling and sizing are performed, and the high-temperature-resistant and flame-retardant composite HDPE pipe material is obtained. Example 5

[0086] The high-temperature-resistant and flame-retardant composite HDPE pipe material is different from example 1 in that the heat-stable reinforcing agent in the raw materials is the modified carbon fiber obtained in preparation example 2, and the other steps are the same as those in example 1. Example 6

[0087] The high-temperature-resistant and flame-retardant composite HDPE pipe material is different from example 1 in that the heat-stable reinforcing agent in the raw materials is the modified carbon fiber obtained in preparation example 3, and the other steps are the same as those in example 1. Example 7

[0088] The high-temperature-resistant and flame-retardant composite HDPE pipe material is different from example 1 in that the filler in the raw materials is talc, and the other steps are the same as those in example 1. Example 8

[0089] The high-temperature-resistant and flame-retardant composite HDPE pipe material is different from example 1 in that the filler in the raw materials is talc and nano active calcium carbonate with a mass ratio of 1:1, and the other steps are the same as those in example 1. Example 9

[0090] The high-temperature-resistant and flame-retardant composite HDPE pipe material is different from example 1 in that the filler in the raw materials is talc and nano active calcium carbonate with a mass ratio of 1:2, and the other steps are the same as those in example 1. Example 10

[0091] The high-temperature-resistant and flame-retardant composite HDPE pipe material is different from example 1 in that the filler in the raw materials is talc and nano active calcium carbonate with a mass ratio of 1:3, and the other steps are the same as those in example 1. Example 11

[0092] A high-temperature-resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the heat-stable reinforcing agent in the raw material is the modified carbon fiber obtained in Preparation Example 4, and other steps are the same as those in Example 1. Example 12

[0093] A high-temperature-resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the heat-stable reinforcing agent in the raw material is a heat stabilizer, dibutyltin dilaurate, and other steps are the same as those in Example 1. Comparative Example

[0094] Comparative Example 1

[0095] A high-temperature-resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the decabromodiphenyl ethane and brominated polystyrene of the original composite flame retardant in the raw material are respectively replaced with equal mass of antimony trioxide, and other steps are the same as those in Example 1.

[0096] Comparative Example 2

[0097] A high-temperature-resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the antimony trioxide of the original composite flame retardant in the raw material is replaced with equal mass of decabromodiphenyl ethane, and other steps are the same as those in Example 1.

[0098] Comparative Example 3

[0099] A high-temperature-resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the decabromodiphenyl ethane of the original composite flame retardant in the raw material is replaced with equal mass of brominated polystyrene, and other steps are the same as those in Example 1.

[0100] Comparative Example 4

[0101] A high-temperature-resistant flame-retardant composite HDPE pipe, which is different from Example 1 in that the brominated polystyrene of the original composite flame retardant in the raw material is replaced with equal mass of decabromodiphenyl ethane, and other steps are the same as those in Example 1.

[0102] Performance detection test

[0103] The high-temperature-resistant flame-retardant composite HDPE pipes obtained in Examples 1-12 and Comparative Examples 1-4 were respectively subjected to the following relevant performance detection tests, each test was tested 3 times, the average value of the test results of the 3 tests was taken as the final result, and the final result was recorded in Table 2.

[0104] 1. Combustion performance: According to the provisions of GB 8624-2012, the high-temperature-resistant flame-retardant composite HDPE pipes obtained from Examples 1-12 and Comparative Examples 1-4 were tested for the flame growth rate index, the total heat release within 600 s, and the flame tip height within 60 s, while observing the lateral spread of the flame and whether the burning droplets could ignite the filter paper, and judging the flame-retardant grade of the product.

[0105] 2. Mechanical properties: According to the provisions of GB / T 8804.2-2016, the tensile strength of the high-temperature-resistant flame-retardant composite HDPE pipes obtained from Examples 1-12 and Comparative Examples 1-4 was tested.

[0106] Table 2

[0107]

[0108] During the above-mentioned related performance test, the lateral spread of the combustion flame of the high-temperature-resistant flame-retardant composite HDPE pipes obtained from Examples 1-12 and Comparative Examples 1-4 did not reach the long wing edge of the sample, and there was no phenomenon of burning droplets igniting the filter paper within 60 s. This indicates that the above-mentioned high-temperature-resistant flame-retardant composite HDPE pipes all have basic flame-retardant ability, can prevent the lateral spread of the flame, and the droplets produced during combustion are not easy to ignite.

[0109] According to the performance test results in Table 2, the high-temperature-resistant flame-retardant composite HDPE pipe of the present application has good high-temperature resistance and combustion suppression ability, can achieve excellent flame-retardant ability without sacrificing the physical properties of the polyethylene pipe itself, and can meet the safety and flame-retardant high-temperature-resistant standard requirements for application in electric wires and cables.

[0110] According to the performance test results of Examples 1-4 and Comparative Examples 1-4, it can be seen that under the raw material ratio of the present application, using antimony trioxide mixed with decabromodiphenyl ethane and brominated polystyrene as a composite flame retardant has a more significant effect on the improvement of the flame-retardant properties of the polyethylene pipe compared to single antimony trioxide or single organic flame retardant.

[0111] According to the performance test results of Examples 1-6 and Examples 7-10, it can be seen that talc and nano active calcium carbonate both have good high-temperature resistance, and when used in combination, they can further enhance the dispersion stability of the polyethylene pipe raw materials, enhance the flame-retardant effect, ensure that the polyethylene pipe has good mechanical properties, and maintain the stability of the material structure.

[0112] According to the performance test results of embodiments 1-4 and 11-12, it can be seen that the modified carbon fiber can not only promote the polyethylene pipe to ensure good high-temperature resistance and flame retardance, but also can improve the mechanical properties of the polyethylene pipe, and reduce the influence of the use of fillers and other additives on the physical properties of the polyethylene pipe.

[0113] In embodiment 11, the modified carbon fiber is not soaked in the fatty alcohol ether phosphate potassium salt solution, and the final flame retardant performance and mechanical properties are both decreased. This may be due to the decrease in the dispersion uniformity of the modified carbon fiber, resulting in the poor combination and dispersion of the modified carbon fiber in the polyethylene matrix. On the other hand, the lack of fatty alcohol ether phosphate salt may not be able to introduce phosphorus-containing functional groups into the raw material of the polyethylene pipe. The introduction of phosphorus-containing functional groups may decompose phosphoric acid or other phosphorus-containing compounds at high temperatures, which can make the polymer surface rapidly dehydrate and carbonize to form a carbonized layer, further hinder the spread of the flame, and improve the overall flame retardant effect.

[0114] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. A high temperature resistant, flame retardant composite HDPE pipe material, characterized in that, The raw materials include 40-45 parts of polyethylene, 0.5-1 part of lubricant, 6-7.6 parts of filler, 2.4-4 parts of composite flame retardant, 1-3 parts of heat-stable reinforcing agent and 1.5-2.5 parts of compatibilizer by weight; The composite flame retardant includes (3-5):(1-2):(0.4-1) of decabromodiphenyl ethane, antimony trioxide and brominated polystyrene; The filler is calcium carbonate, and the heat-stable reinforcing agent is modified carbon fiber; The preparation method of the modified carbon fiber comprises the following steps: S1: cleaning and drying the carbon fiber to remove surface impurities; S2: soaking the carbon fiber treated in step S1 in a fatty alcohol ether phosphate potassium salt solution for 1-2 hours, filtering and drying at 100-110°C for 2-4 hours to obtain the modified carbon fiber.

2. The high temperature resistant, flame retardant, composite HDPE pipe as claimed in claim 1, wherein, The filler is talcum powder and nano active calcium carbonate with a mass ratio of (1-3):

1.

3. The high temperature resistant, flame retardant, composite HDPE pipe as claimed in claim 1, wherein, The lubricant is selected from any one or a combination of more than one of calcium stearate, zinc stearate, barium stearate and paraffin wax.

4. The high temperature resistant, flame retardant, composite HDPE pipe as claimed in claim 1, wherein, The compatibilizer is selected from any one of PP-g-MAH or EAA.

5. A process for the preparation of a high temperature resistant, flame retardant composite HDPE pipe as claimed in any one of claims 1 to 4, characterized in that, The method comprises the following steps: According to the weight parts of the raw materials, each raw material is weighed, and all the raw materials are first hot mixed at 100-110°C and then cold mixed at 30-40°C to obtain a blend; The blend is sent into a screw extruder for extrusion molding, vacuum cooling and sizing after extrusion through a mold to obtain the product.

6. A process for the preparation of high temperature resistant, flame retardant composite HDPE pipes as claimed in claim 5, wherein, The processing technology of the screw extruder is as follows: The feeding screw rotation speed is 40-60 r / min, and the main screw rotation speed is 300-500 r / min; The temperature of the first to third zones is 190-220°C, the temperature of the fourth to sixth zones is 230-250°C, and the temperature of the seventh to ninth zones is 200-230°C.

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