A corrosion-resistant and flame-retardant composite material pipe and its preparation method

Abstract

The present invention relates to the field of flame retardant materials, and in particular to a corrosion-resistant flame retardant composite material pipe and a preparation method thereof, wherein the composite material pipe is calculated by weight, including: 60-80 parts of nylon resin, 15-25 parts of glass fiber, 5-18 parts of halogen-free flame retardant, 3-7 parts of compatibilizer, 2.1-3.5 parts of lubricant, 0.6-1.2 parts of antioxidant and 1-3 parts of antistatic agent; the halogen-free flame retardant is prepared by the click chemical reaction of propylene phosphoamidated hectorite and mercaptobenzimidazole through thiol-double bonds. The flame retardant prepared by the present invention not only has relatively excellent environmental protection and flame retardancy, but also has a great degree of improvement in the cold resistance, impact resistance and acid resistance of nylon materials.

Description

Technical Field

[0001] The invention relates to the field of flame retardant materials, and in particular to a corrosion-resistant flame retardant composite material pipe and a preparation method thereof. Background Art

[0002] Flame retardant pipes are suitable for liquid transportation with general working pressure in the fields of industry, agriculture, food, medicine, civil engineering, fishery, aquaculture, garden irrigation, etc. Such as: pneumatic pipes, hydraulic pipes, garden hoses, oil and water pipelines, oil exploration pipes, sandblasting pipes, peristaltic pump hoses, industrial robots, pneumatic tools, assembly plant air pressure tools, pressure delivery pipelines, can be used as vacuum straws, protective jackets or decorations for metal and electronic products. Nylon, also known as polyamide, is a thermoplastic polymer containing amide group repeating units in the main chain of the molecule. The amide group repeating unit can be obtained by condensation of dicarboxylic acid and diamine, or by opening of lactam. Nylon resin has good wear resistance, flexibility, dyeability and durability, and is widely used in clothing, stockings, clothing and industrial rope nets. As a nylon resin, in addition to the amide group repeating unit in the main chain of the molecule, it often contains a large number of methylene structural units. This causes nylon resin to burn easily, especially resin-reinforced nylon resin. Due to the candle wick effect, the limiting oxygen index is only 23%, and the vertical combustion level is no level. However, in many specific fields, there is an urgent need to provide nylon resins with better flame retardant properties.

[0003] At present, many flame retardants used in nylon materials are mainly halogen-based organic flame retardants such as decabromodiphenylethane and brominated polystyrene. Although these flame retardants have good flame retardant effects, they will produce toxic smoke during the combustion process, which can easily cause adverse effects on the human body and the environment. Although inorganic flame retardants have overcome many defects of halogen-based organic flame retardants, they need to be added in large quantities to achieve flame retardant effects, which seriously affects the mechanical properties of the material. In addition, nylon materials themselves have good chemical stability and corrosion resistance, have good tolerance to many chemical substances, and can maintain stability in general acid-base corrosive environments, but are still easily corroded under strong acid conditions. Therefore, for the development of flame-retardant nylon materials, we should not only pay attention to the environmental protection and flame retardant effects of the materials, but also consider the comprehensive performance of the materials. Summary of the invention

[0004] In view of the problems existing in the prior art, an object of the present invention is to provide a corrosion-resistant and flame-retardant composite material pipe and a preparation method thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] In a first aspect, the present invention provides a corrosion-resistant flame-retardant composite material pipe, calculated by weight, comprising:

[0007] 60 - 80 parts of nylon resin, 15 - 25 parts of glass fiber, 5 - 18 parts of halogen - free flame retardant, 3 - 7 parts of compatibilizer, 2.1 - 3.5 parts of lubricant, 0.6 - 1.2 parts of antioxidant and 1 - 3 parts of antistatic agent.

[0008] Preferably, the nylon resin is one or a mixture of more than one of PA6, PA66, PA11, PA12, PA1010, and PA1212.

[0009] More preferably, the nylon resin is PA66, with a density of 1.15 g / cm 3 , and a melt index of 18 g / 10 min (190 °C, 2.16 kg).

[0010] Preferably, the glass fiber is an alkali - free glass fiber, with a density of 2.6 g / cm 3 , a diameter of 11 - 13 μm, and a length of 0.3 - 0.6 mm.

[0011] Preferably, the flame retardant is prepared by the click chemical reaction of allylphosphonamide - modified hectorite and mercaptobenzimidazole through a thiol - double bond reaction.

[0012] Preferably, the compatibilizer is maleic anhydride - grafted polyolefin elastomer (POE - g - MAH), with a grafting rate of 1.2%, and a density of 0.87 g / cm 3 , and a melt index of 1.8 g / 10 min (190 °C, 2.16 kg).

[0013] Preferably, the lubricant is one or a mixture of more than one of oxidized polyethylene wax, ethylene bisstearamide, paraffin wax, and polyethylene wax.

[0014] Preferably, the antioxidant is a phenolic antioxidant, including one or a combination of more than one of antioxidant 1098, antioxidant 1076, and antioxidant 1010.

[0015] Preferably, the antistatic agent is one or a mixture of more than one of polyether ester acetamide, polyether ester amide, polyethylene oxide, polyoxyethylene castor oil, and polyoxyethylene laurate.

[0016] Preferably, the preparation method of the halogen - free flame retardant includes:

[0017] S1. Weigh hectorite powder and mix it into an ethanol solution of 30 - 50 wt%, disperse it evenly in an ultrasonic disperser, add an amino - silane coupling agent, then place it in a water bath at 70 - 80 °C, reflux and stir for 6 - 10 h. After the treatment, separate, wash, and dry to obtain amino - modified hectorite;

[0018] S2. Weigh allylenephosphonyl chloride and add it to tetrahydrofuran. After stirring and dissolving, add aminated hectorite, mix well, then add triethylamine dropwise. First, stir at room temperature for 1 - 5 h, then reflux at 60 - 70 °C for 6 - 12 h. After the reaction is completed, remove the solvent, wash and dry to obtain allylenephosphonamidated hectorite;

[0019] S3. Weigh mercaptobenzimidazole and add it to anhydrous ethanol. After stirring and dissolving, add allylenephosphonamidated hectorite, disperse evenly at room temperature, add a photoinitiator, irradiate with an LED ultraviolet lamp while continuously stirring, and react for 0.5 - 1.5 h. After the reaction is completed, remove the solvent under reduced pressure to obtain a halogen-free flame retardant.

[0020] Preferably, in S1, the particle size of the hectorite powder is 10 - 15 μm, and the manufacturer is Zhejiang Huate New Materials Co., Ltd.

[0021] Preferably, in S1, the mass - volume ratio of the hectorite powder, amino - silane coupling agent, and ethanol solution is 1 g:(0.2 - 0.8) g:(10 - 20) mL.

[0022] Preferably, in S1, the mercapto - silane coupling agent is γ - aminopropyltriethoxysilane or γ - aminopropyltrimethoxysilane.

[0023] Preferably, in S2, the mass - volume ratio of the aminated hectorite, allylenephosphonyl chloride, triethylamine, and tetrahydrofuran is 1 g:(0.27 - 0.81) g:(0.13 - 0.26) g:(10 - 20) mL.

[0024] Preferably, in S3, the mass - volume ratio of the allylenephosphonamidated hectorite, mercaptobenzimidazole, and anhydrous ethanol is (1.1 - 1.5) g:(0.3 - 0.6) g:(30 - 50) mL.

[0025] Preferably, in S3, the photoinitiator is benzoin dimethyl ether, and the addition amount is 3.5% - 7.5% of the mass of mercaptobenzimidazole.

[0026] Preferably, in S3, the wavelength of the LED ultraviolet lamp is 325 - 390 nm, and the light intensity is 1.3 - 2.6 mW / cm 2 .

[0027] Second, the present invention provides a preparation method of a corrosion - resistant and flame - retardant composite material pipe, including the following steps:

[0028] Step 1. Weigh other raw materials except glass fiber and mix them in a blender, stir at a speed of 300 - 600 r / min until fully mixed to obtain a mixed raw material;

[0029] Step 2: Then, introduce the mixed raw materials into a twin-screw extruder, add glass fiber through side feeding, melt and extrude into pellets. The extrusion temperature is 255 - 285°C, the screw speed is 80 - 120 r / min, and the length-diameter ratio L / D is 35 - 45 to obtain composite masterbatch.

[0030] Step 3: Place the composite masterbatch in a mold for processing and forming to obtain a corrosion-resistant and flame-retardant composite material pipe.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. The present invention prepares a flame-retardant composite material pipe. The main material of the composite material pipe is nylon resin, with glass fiber as the main reinforcing agent. The flame retardant used is an environment-friendly organic-inorganic coated flame retardant. A compatibilizer is also added to improve the compatibility between nylon resin and other materials. In addition, additives such as lubricants, antioxidants, and antistatic agents are added. Finally, the obtained composite material pipe has the properties of high strength, high flame retardancy, corrosion resistance, and environmental protection.

[0033] 2. In the present invention, the halogen-free flame retardant used is an environment-friendly flame retardant without halogen, which is prepared by the thiol-ene click chemical reaction of allylphosphonamidated hectorite and mercaptobenzimidazole. Among them, the preparation of allylphosphonamidated hectorite is to first amino-activate hectorite, and then carry out a nucleophilic addition reaction with allylphosphonyl chloride to form a phosphonamide group, thereby obtaining an organic-inorganic coated structure containing double bonds and phosphonamide groups.

[0034] 3. The flame retardant prepared by the present invention not only has excellent environmental protection and flame retardancy, but also greatly improves the cold resistance, impact resistance, and acid resistance of nylon materials. Description of the Drawings

[0035] The present invention is further described with the aid of the drawings, but the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the following drawings.

[0036] Figure 1 It is a scanning electron microscope schematic diagram of the halogen-free flame retardant prepared in Example 1 of the present invention. Detailed Embodiments

[0037] The technical solutions of the present invention will be described below through specific specific examples. It should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps or the insertion of other method steps between these clearly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Moreover, unless otherwise stated, the numbers of each method step are only convenient tools for identifying each method step, rather than limiting the arrangement order of each method step or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope in which the present invention can be implemented.

[0038] To better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail below. Although the exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0039] The present invention will be further described below in conjunction with the following embodiments. Example 1

[0040] A corrosion-resistant and flame-retardant composite material pipe, calculated by weight parts, includes:

[0041] 70 parts of nylon resin PA66, 20 parts of E-glass fiber, 12 parts of halogen-free flame retardant, 5 parts of compatibilizer POE-g-MAH, 2.8 parts of lubricant, 0.9 part of antioxidant and 2 parts of antistatic agent.

[0042] Among them, the density of nylon resin PA66 is 1.15 g / cm 3 , and the melt index is 18 g / 10 min (190 °C, 2.16 kg); the density of E-glass fiber is 2.6 g / cm 3 , the diameter is 11 - 13 μm, and the length is 0.3 - 0.6 mm; the grafting rate of compatibilizer POE-g-MAH is 1.2%, the density is 0.87 g / cm 3 , and the melt index is 1.8 g / 10 min (190 °C, 2.16 kg); the lubricant is oxidized polyethylene wax; the antioxidant is antioxidant 1098; the antistatic agent is polyether ester acetamide.

[0043] Among them, the preparation method of the halogen-free flame retardant includes:

[0044] S1. Weigh the hectorite powder with a particle size of 10-15 μm and mix it with a 40wt% ethanol solution, disperse it evenly in an ultrasonic disperser, add γ-aminopropyltriethoxysilane, the mass volume ratio of hectorite powder, γ-aminopropyltriethoxysilane and ethanol solution is 1g:0.5g:15mL, then place it in a 75°C water bath, reflux and stir for 8h, and after the treatment, separate, wash and dry to obtain amino hectorite;

[0045] S2, weigh allene phosphonyl chloride and add it to tetrahydrofuran, stir and dissolve, add amination hectorite, mix well, then dropwise add triethylamine, the mass volume ratio of amination hectorite, allene phosphonyl chloride, triethylamine and tetrahydrofuran is 1g:0.54g:0.2g:15mL, then stir at room temperature for 2h, then keep warm and reflux at 68°C for 8h, after the reaction is completed, remove the solvent, wash and dry to obtain allene phosphonyl amidated hectorite;

[0046] S3. Weigh mercaptobenzimidazole and add it to anhydrous ethanol. Stir and dissolve it at room temperature. Then add allenephosphinamide hectorite and continue to disperse it evenly at room temperature. The mass volume ratio of allenephosphinamide hectorite, mercaptobenzimidazole and anhydrous ethanol is 1.3g:0.5g:40mL. Then, add benzoin dimethyl ether (5.5% of the mass of mercaptobenzimidazole) as an initiator. Use a wavelength of 365nm and a light intensity of 2.2mW / cm 2 The mixture was irradiated with an LED ultraviolet lamp while being continuously stirred for 1 hour. After the reaction, the solvent was removed under reduced pressure to obtain a halogen-free flame retardant.

[0047] The method for preparing the corrosion-resistant and flame-retardant composite material pipe comprises the following steps:

[0048] Step 1, weighing other raw materials except glass fiber and mixing them in a mixer, stirring at a speed of 400 r / min until fully mixed to obtain a mixed raw material;

[0049] Step 2, then introducing the mixed raw materials into a twin-screw extruder, adding glass fiber through side feeding, melt extrusion granulation, the extrusion temperature is 255-285° C., the screw speed is 100 r / min, the aspect ratio L / D is 40, and a composite material masterbatch is obtained;

[0050] Step 3, placing the composite material masterbatch in a mold for processing and forming to obtain a corrosion-resistant and flame-retardant composite material tube. Example 2

[0051] A corrosion-resistant flame-retardant composite material pipe, calculated by weight, comprising:

[0052] 60 parts of nylon resin PA6, 15 parts of E-glass fiber, 5 parts of halogen-free flame retardant, 3 parts of POE-g-MAH, 2.1 parts of lubricant, 0.6 part of antioxidant and 1 part of antistatic agent.

[0053] Among them, the density of the E-glass fiber is 2.6 g / cm 3 , the diameter is 11 - 13 μm, and the length is 0.3 - 0.6 mm; for the compatibilizer POE-g-MAH, the grafting rate is 1.2%, and the density is 0.87 g / cm 3 , and the melt index is 1.8 g / 10 min (190 °C, 2.16 kg); the lubricant is paraffin wax; the antioxidant is antioxidant 1076; the antistatic agent is polyether ester amide.

[0054] Among them, the preparation method of the halogen-free flame retardant includes:

[0055] S1. Weigh the palygorskite powder with a particle size of 10 - 15 μm and mix it into a 30 wt% ethanol solution, disperse it evenly in an ultrasonic disperser, add γ-aminopropyltrimethoxysilane, and the mass-volume ratio of palygorskite powder, γ-aminopropyltrimethoxysilane and absolute ethanol is 1 g:0.2 g:10 mL. Then place it in a water bath at 70 °C, reflux and stir for 6 h. After the treatment, separate, wash and dry to obtain amino-functionalized palygorskite;

[0056] S2. Weigh allylphosphonyl chloride and add it to tetrahydrofuran. After stirring and dissolving, add amino-functionalized palygorskite and mix well. Then add triethylamine. The mass-volume ratio of amino-functionalized palygorskite, allylphosphonyl chloride, triethylamine and tetrahydrofuran is 1 g:0.27 g:0.13 g:10 mL. First, stir at room temperature for 1 h, then keep it at 60 °C for heat reflux for 6 h. After the reaction, remove the solvent, wash and dry to obtain allylphosphonamide-functionalized palygorskite;

[0057] S3. Weigh mercaptobenzimidazole and add it to absolute ethanol. First, stir and dissolve it at room temperature, then add allylphosphonamide-functionalized palygorskite and continue to disperse it evenly at room temperature. The mass-volume ratio of allylphosphonamide-functionalized palygorskite, mercaptobenzimidazole and absolute ethanol is 1.1 g:0.3 g:30 mL. Then add benzoin dimethyl ether with a mass of 3.5% of mercaptobenzimidazole as an initiator, and irradiate it with an LED ultraviolet lamp with a wavelength of 365 nm and a light intensity of 1.8 mW / cm 2 while continuously stirring. React for 0.5 h. After the reaction, remove the solvent under reduced pressure to obtain the halogen-free flame retardant.

[0058] The preparation method of the above corrosion-resistant and flame-retardant composite material pipe includes the following steps:

[0059] Step 1, weighing other raw materials except glass fiber and mixing them in a blender, stirring at a speed of 300 r / min until fully mixed to obtain a mixed raw material;

[0060] Step 2, then introducing the mixed raw materials into a twin-screw extruder, adding glass fiber through side feeding, melt extrusion granulation, the extrusion temperature is 255-285° C., the screw speed is 80 r / min, the aspect ratio L / D is 35, and a composite material masterbatch is obtained;

[0061] Step 3, placing the composite material masterbatch in a mold for processing and forming to obtain a corrosion-resistant and flame-retardant composite material tube. Example 3

[0062] A corrosion-resistant flame-retardant composite material pipe, calculated by weight, comprising:

[0063] 80 parts of nylon resin PA12, 25 parts of alkali-free glass fiber, 18 parts of halogen-free flame retardant, 7 parts of POE-g-MAH, 3.5 parts of lubricant, 1.2 parts of antioxidant and 3 parts of antistatic agent.

[0064] Among them, the density of alkali-free glass fiber is 2.6g / cm 3 , diameter is 11-13μm, length is 0.3-0.6mm; the grafting rate of compatibilizer POE-g-MAH is 1.2%, and the density is 0.87g / cm 3 , melt index is 1.8g / 10min (190℃, 2.16kg);

[0065] The lubricant is polyethylene wax; the antioxidant is a phenolic antioxidant, including antioxidant 1010; and the antistatic agent is a mixture of one or more of polyether ester acetamide, polyether ester amide, polyethylene oxide, polyoxyethylene castor oil, and polyoxyethylene laurate.

[0066] The preparation method of the halogen-free flame retardant comprises:

[0067] S1. Weigh the hectorite powder with a particle size of 10-15 μm and mix it into a 50wt% ethanol solution, disperse it evenly in an ultrasonic disperser, add γ-aminopropyltriethoxysilane, the mass volume ratio of hectorite powder, γ-aminopropyltriethoxysilane and anhydrous ethanol is 1g:0.8g:20mL, then place it in a water bath at 80°C, reflux and stir for 10h, and after the treatment, separate, wash and dry to obtain amino hectorite;

[0068] S2. Weigh allylphosphonyl chloride and add it to tetrahydrofuran. After stirring and dissolving, add amino-functionalized hectorite, mix well, and then add triethylamine dropwise. The mass-volume ratio of amino-functionalized hectorite, allylphosphonyl chloride, triethylamine, and tetrahydrofuran is 1 g: 0.81 g: 0.26 g: 20 mL. Then, stir at room temperature for 5 h first, and then keep it under reflux at 70 °C for 12 h. After the reaction is completed, remove the solvent, wash, and dry to obtain allylphosphonamide-functionalized hectorite.

[0069] S3. Weigh mercaptobenzimidazole and add it to absolute ethanol. After stirring and dissolving at room temperature first, add allylphosphonamide-functionalized hectorite and continue to disperse evenly at room temperature. The mass-volume ratio of allylphosphonamide-functionalized hectorite, mercaptobenzimidazole, and absolute ethanol is 1.5 g: 0.6 g: 50 mL. Then, add benzoin dimethyl ether, which is 7.5% of the mass of mercaptobenzimidazole, as an initiator. Use an LED ultraviolet lamp with a wavelength of 365 nm and a light intensity of 2.6 mW / cm 2 to irradiate while constantly stirring. React for 1.5 h. After the reaction is completed, remove the solvent under reduced pressure to obtain a halogen-free flame retardant.

[0070] The preparation method of the above corrosion-resistant and flame-retardant composite material pipe includes the following steps:

[0071] Step 1. Weigh other raw materials except glass fiber and mix them in a blender, stir at a speed of 600 r / min until fully mixed to obtain a mixed raw material.

[0072] Step 2. Then, introduce the mixed raw material into a twin-screw extruder, add glass fiber through side feeding, melt and extrude into pellets. The extrusion temperature is 255 - 285 °C, the screw speed is 120 r / min, and the length-diameter ratio L / D is 45 to obtain a composite material masterbatch.

[0073] Step 3. Place the composite material masterbatch in a mold for processing and forming to obtain a corrosion-resistant and flame-retardant composite material pipe.

[0074] Comparative Example 1

[0075] A flame-retardant composite material pipe, which is different from Example 1 only in that the halogen-free flame retardant is replaced with hectorite powder.

[0076] Comparative Example 2

[0077] A flame-retardant composite material pipe, which is different from Example 1 only in that the halogen-free flame retardant is replaced with allylphosphonamide-functionalized hectorite (prepared in the same way as in Example 1).

[0078] Comparative Example 3

[0079] A flame-retardant composite material pipe, which is only different from that of Example 1 in that the halogen-free flame retardant is replaced with a mixture of hydrotalcite powder and mercaptobenzimidazole, and the mass ratio of hydrotalcite powder to mercaptobenzimidazole is 1.3:0.5.

[0080] Experimental Example

[0081] Performance tests and comparisons were carried out on the composite material pipes prepared in Example 1 and Comparative Examples 1-3. The relevant test standards include: tensile strength referring to ISO 527-2:2012, notched izod impact strength referring to ISO 179-1:2010, limiting oxygen index referring to ISO 4589-2:1996, flame retardant rating referring to ANSI / UL-94-1985, acid resistance test: soaking in 0.1 mol / L hydrochloric acid solution at room temperature for 48 h, and detecting the change rate of tensile strength; the test results are shown in Table 1:

[0082] Table 1 Performance test results of different composite material pipes

[0083]

[0084] It can be seen from Table 1 that the composite material pipe prepared in Example 1 of the present invention has higher tensile strength and impact strength at room temperature, and the impact strength at low temperature (-30 °C) is also better than that of the comparative examples. In addition, the composite material pipe prepared in Example 1 of the present invention also has better flame retardancy and acid resistance, indicating that its comprehensive performance is better and it is suitable for use in more severe environments.

[0085] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0086] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A corrosion-resistant and flame-retardant composite material pipe, characterized in that: Calculated by weight, including: 60-80 parts of nylon resin, 15-25 parts of glass fiber, 5-18 parts of halogen-free flame retardant, 3-7 parts of compatibilizer, 2.1-3.5 parts of lubricant, 0.6-1.2 parts of antioxidant and 1-3 parts of antistatic agent; The halogen-free flame retardant is prepared by a click chemical reaction of sulfhydryl-double bond of allene phosphinamidated hectorite and mercaptobenzimidazole.

2. The corrosion-resistant and flame-retardant composite material pipe according to claim 1, characterized in that: The nylon resin is one of PA6, PA66, PA11, PA12, PA1010, and PA1212, or a mixture of more thereof.

3. The corrosion-resistant and flame-retardant composite material pipe according to claim 1, characterized in that: The glass fiber is alkali-free glass fiber with a density of 2.6 g / cm 3 , with a diameter of 11-13 μm and a length of 0.3-0.6 mm; the compatibilizer is a maleic anhydride grafted polyolefin elastomer with a grafting rate of 1.2% and a density of 0.87 g / cm 3 The melt index at 190°C and 2.16kg is 1.8g / 10min.

4. The corrosion-resistant and flame-retardant composite material pipe according to claim 1, characterized in that: The lubricant is a mixture of one or more of oxidized polyethylene wax, ethylene bisstearamide, paraffin, and polyethylene wax; the antioxidant is a phenolic antioxidant, including one or more combinations of antioxidant 1098, antioxidant 1076, and antioxidant 1010; the antistatic agent is a mixture of one or more of polyether ester amide, polyether ester amide, polyethylene oxide, polyoxyethylene castor oil, and polyoxyethylene laurate.

5. The corrosion-resistant and flame-retardant composite material pipe according to claim 1, characterized in that: The preparation method of the halogen-free flame retardant comprises: S1. Weigh the hectorite powder and mix it with the ethanol solution, disperse it evenly in an ultrasonic disperser, add the aminosilane coupling agent, and then place it in a water bath at 70-80° C. and reflux and stir for 6-10 hours. After the treatment, separate, wash and dry to obtain the amino hectorite; S2, weigh allenephosphonyl chloride and add it to tetrahydrofuran, stir and dissolve, add amination hectorite, mix well, then drop triethylamine, stir at room temperature for 1-5h, then keep warm and reflux at 60-70°C for 6-12h, after the reaction is completed, remove the solvent, wash and dry to obtain allenephosphonyl amidation hectorite; S3. Weigh mercaptobenzimidazole and add it to anhydrous ethanol. After stirring to dissolve, add allenephosphonamidite hectorite and disperse evenly at room temperature. Add a photoinitiator and irradiate with an LED ultraviolet lamp while stirring continuously. React for 0.5-1.5 hours. After the reaction is completed, remove the solvent under reduced pressure to obtain a halogen-free flame retardant.

6. The corrosion-resistant and flame-retardant composite material pipe according to claim 5, characterized in that: In the S1, the mass volume ratio of the hectorite powder, the aminosilane coupling agent and the ethanol solution is 1 g: (0.2-0.8) g: (10-20) mL; and the mass fraction of the ethanol solution is 30%-50%.

7. The corrosion-resistant and flame-retardant composite material pipe according to claim 5, characterized in that: In S2, the mass volume ratio of amination hectorite, allenephosphonyl chloride, triethylamine and tetrahydrofuran is 1 g: (0.27-0.81) g: (0.13-0.26) g: (10-20) mL.

8. The corrosion-resistant and flame-retardant composite material pipe according to claim 5, characterized in that: In S3, the mass volume ratio of allenephosphonamidated hectorite, mercaptobenzimidazole and anhydrous ethanol is (1.1-1.5) g: (0.3-0.6) g: (30-50) mL.

9. The corrosion-resistant and flame-retardant composite material pipe according to claim 5, characterized in that: In S3, the photoinitiator is benzoin dimethyl ether, and the added amount is 3.5%-7.5% of the mass of mercaptobenzimidazole; the wavelength of the LED ultraviolet lamp is 325-390nm, and the light intensity is 1.3-2.6mW / cm 2 .

10. A method for preparing the corrosion-resistant and flame-retardant composite material pipe according to claim 1, characterized in that: The following steps are involved: Step 1, weighing other raw materials except glass fiber, mixing them in a blender, and stirring at a speed of 300-600 r / min until fully mixed to obtain a mixed raw material; Step 2, then introducing the mixed raw materials into a twin-screw extruder, adding glass fiber through side feeding, melt extrusion granulation, the extrusion temperature is 255-285°C, the screw speed is 80-120r / min, the aspect ratio L / D is 35-45, and a composite material masterbatch is obtained; Step 3, placing the composite material masterbatch in a mold for processing and forming to obtain a corrosion-resistant and flame-retardant composite material tube.

Images