Chitosan-based high-flame-retardant mpp pipe and preparation method thereof

Abstract

The application discloses a kind of chitosan-based high flame-retardant MPP pipes and preparation method thereof, belong to flame-retardant pipe technical field.The chitosan-based high flame-retardant MPP pipe includes following weight fraction each component: polypropylene 63~68 parts, filler 15~20 parts, chitosan-based flame retardant 12~17 parts, lubricant 1~3 parts, antioxidant 0.5~2 parts;Wherein, the chitosan-based flame retardant is obtained by chitosan and silane coupling agent KH-792 at 50~80 DEG C under reaction.This application is by using chitosan modified by silane coupling agent KH-792 as flame retardant, under the joint action of silane coupling agent KH-792 and chitosan, the flame retardant has excellent flame-retardant capacity, the flame retardant is added to MPP pipe, can be well prevented MPP pipe thermal decomposition, significantly improve the flame-retardant performance of MPP pipe;Meanwhile, using low-cost chitosan to prepare flame retardant can also reduce the cost of flame retardant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame-retardant pipes, in particular to a chitosan-based high-flame-retardant MPP pipe and a preparation method thereof. BACKGROUND

[0002] MPP pipe, also known as MPP power cable protection pipe, uses modified polypropylene (MPP) as the main raw material. MPP power pipe is one of the conventional power pipes mainly used in the market at present, and is suitable for 10KV or below medium and low voltage power transmission cable pipe material. MPP pipe plays an important role in motor technology; however, with the gradual expansion of its application field and environment, its shortcomings are becoming more and more prominent. In the actual use process, MPP pipe in a high temperature environment can easily accumulate a large amount of heat energy due to power transmission, which is prone to flammability, affecting the normal use of the subsequent MPP pipe, causing economic cost loss, and also having certain safety hazards, which does not meet the use needs of power technology, and therefore its flame-retardant performance needs to be improved.

[0003] In order to improve the flame-retardant performance of MPP pipe, various types of flame retardants are usually introduced. At present, there are many flame retardants for PP modification, such as halogen-based flame retardants, intumescent flame retardants, phosphorus-based flame retardants, metal hydroxides, etc. For example, Chinese patent CN109679208A discloses an environmentally friendly high-efficiency flame-retardant polypropylene composite and a preparation method thereof, which comprises the following raw material components by weight: polypropylene 35-74 parts, halogen-free flame retardant 15-30 parts, antioxidant 1-2 parts, coupling agent 0.5-2 parts, and other additives 0-2 parts; wherein the halogen-free flame retardant is composed of modified ammonium polyphosphate, nano carbon spheres and hydroxyapatite; the nano carbon spheres are prepared from glucose; and the modified ammonium polyphosphate is prepared by coating polyphosphoric acid ammonium with methyl silane with a polymerization degree greater than 1700. The present application adds halogen-free flame retardant to the polypropylene composite, which gives the composite good flame-retardant performance while maintaining good mechanical properties. In addition, it avoids the pollution to the environment and the harm to the human body caused by traditional halogen-based flame-retardant polypropylene materials, and is non-toxic and environmentally friendly. However, the flame-retardant performance of the polypropylene composite is generally not high and needs to be improved.

[0004] On the other hand, chitosan is a natural and easily available polysaccharide polymer with low price, and has the characteristics of biodegradability, biocompatibility, environmental friendliness and non-toxicity. Secondly, its molecular skeleton is rich in carbon, and contains a certain number of side chain groups of hydroxyl and amino groups; in the process of thermal decomposition, carbonization in the polymer can hinder the combustion process, and at the same time release non-toxic and non-corrosive non-combustible gases such as CO2, NH3 and N2, thereby playing a flame-retardant role. However, due to the excessive number of hydroxyl and amino groups in chitosan, it has a certain hydrophilic and oleophobic property, and the compatibility with polypropylene (PP) is poor. If it is directly added, it cannot play a good flame-retardant effect. SUMMARY

[0005] In view of the above problems of the prior art, the present application provides a kind of chitosan-based high flame-retardant MPP pipe, which uses chitosan-based flame retardant, and the chitosan-based flame retardant is obtained by using chitosan as raw material and modifying chitosan with silane coupling agent KH-792, which can improve the flame-retardant effect of chitosan and obtain MPP pipe with high flame-retardant performance.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] A kind of chitosan-based high flame-retardant MPP pipe, comprising the following components by weight: polypropylene 63-68 parts, filler 15-20 parts, chitosan-based flame retardant 12-17 parts, lubricant 1-3 parts, antioxidant 0.5-2 parts.

[0008] The chitosan-based flame retardant is obtained by reacting chitosan and silane coupling agent KH-792 at 50-80℃.

[0009] Chitosan has a large number of hydroxyl and amino groups, and its compatibility with PP is poor, so it cannot be well dispersed in MPP pipe, limiting the play of its flame-retardant performance. The present application modifies chitosan with KH-792, effectively improving the lipophilicity and hydrophobicity of chitosan and improving the problem of poor compatibility with PP. More importantly, KH-792 is N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane C8H 22 N2O3Si, which contains abundant carbon source, nitrogen source and silicon source. On the one hand, KH-792 can increase the amount of carbon source in chitosan, and form a porous carbon layer through the action of condensed phase, which can act as a thermal barrier to reduce the heat transfer between heat source and polymer surface, thereby interrupting the combustion of polymer; on the other hand, KH-792 can increase the amount of nitrogen source in chitosan, which can produce a large amount of non-combustible gas when heated or burned, diluting the concentration of oxygen and gaseous combustible products on the surface of the polymer, thereby further improving the flame-retardant performance of chitosan; in addition, KH-792 introduces additional silicon source, which can produce molten droplets when burned, which can transfer through the voids of the polymer matrix to the surface of the substrate to form a dense and stable silicon layer (mainly composed of SiO2), which not only prevents the escape of combustible substances produced by combustion and decomposition, but also plays a role in heat and oxygen insulation. Under the combined action of the above aspects, the flame-retardant performance of chitosan in MPP pipe is ultimately improved, and the chitosan-based flame retardant obtained by reacting chitosan and silane coupling agent KH-792 can effectively prevent the thermal decomposition of MPP pipe, thereby obtaining MPP pipe with high flame-retardant performance.

[0010] Preferably, the chitosan-based high-flame-retardant MPP pipe material comprises the following components in parts by weight: polypropylene 65 parts, filler 17 parts, chitosan-based flame retardant 15 parts, lubricant 2 parts, antioxidant 1 part.

[0011] Preferably, the preparation method of the chitosan-based flame retardant comprises the following steps:

[0012] S1. After drying, the chitosan is dissolved in acetic acid solution, and then acetic acid is added dropwise to adjust the pH value of the solution to 4 to obtain solution A;

[0013] S2. The silane coupling agent KH-792 is dissolved in an aqueous ethanol solution to obtain solution B;

[0014] S3. Under the protection of inert gas, solution A and solution B are mixed to obtain solution C, the mass ratio of chitosan to silane coupling agent KH-792 in solution C is (0.69-1.06):(0.49-1); then react at 50-60℃ for 2-4h, and then continue to react at 60-80℃ for 0.5-1h, and then separate, wash and dry to obtain the chitosan-based flame retardant.

[0015] Preferably, in step S3, the mass ratio of chitosan to silane coupling agent KH-792 in solution C is 0.97:0.61.

[0016] Preferably, the filler comprises talcum powder and powdered quartz.

[0017] Preferably, in step S1, the drying temperature is 100-120℃, and the time is 5-7h; the mass percentage of chitosan in solution A is 1-5%.

[0018] Preferably, in step S2, the mass percentage of silane coupling agent KH-792 in solution B is 1.5-5%.

[0019] Preferably, step S3 further comprises grinding the chitosan-based flame retardant and passing it through a 200-mesh screen.

[0020] Preferably, the lubricant comprises at least one of paraffin wax, PE wax, stearic acid, and calcium stearate; and the antioxidant is a hindered phenolic antioxidant and / or a phosphite antioxidant.

[0021] The application also provides a preparation method of the chitosan-based high-flame-retardant MPP pipe material, comprising the following steps:

[0022] P1. The components are weighed in parts by weight;

[0023] P2. The polypropylene and chitosan-based flame retardant are mixed evenly at 70-90°C to obtain a first mixture; the filler and lubricant are mixed evenly at 100-120°C, then an antioxidant is added, stirring is continued, and then the mixture is kept at 8-10 MPa for 5-15 minutes to obtain a second mixture;

[0024] P3. Add the first mixture and the second mixture to a mixer for blending, heat and stir to 110-120°C and then stop stirring. Cool the material to 40-50°C to obtain the blend. Finally, extrude the blend and granulate it, and then mold it to obtain the chitosan-based high flame-retardant MPP pipe.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. This invention uses chitosan modified with silane coupling agent KH-792 as a flame retardant. Under the combined action of silane coupling agent KH-792 and chitosan, the flame retardant has excellent flame retardant ability. Adding this flame retardant to MPP pipes can effectively prevent the thermal decomposition of MPP pipes and significantly improve the flame retardant performance of MPP pipes. At the same time, using inexpensive chitosan to prepare the flame retardant can also reduce the cost of the flame retardant.

[0027] 2. The MPP pipe of the present invention has high flame retardancy, with a limiting oxygen index as high as 47.3%, and excellent flame retardant performance.

[0028] 3. The flame retardant prepared by the present invention using chitosan as raw material can not only produce low-smoke and low-toxicity flame retardants, but also expand the application field of chitosan. Furthermore, it is of great significance to the effective utilization of chitosan-based materials and the significant improvement of the ecological environment in my country. Detailed Implementation

[0029] The applicant will now provide a detailed description of the method of the present invention with reference to specific embodiments, in order to enable those skilled in the art to clearly understand the present invention. However, the following embodiments should not be construed in any way as limiting the scope of protection claimed in the present invention.

[0030] The chitosan-based high flame-retardant MPP pipe of the present invention comprises the following components in parts by weight: 63-68 parts of polypropylene, 15-20 parts of filler, 12-17 parts of chitosan-based flame retardant, 1-3 parts of lubricant, and 0.5-2 parts of antioxidant.

[0031] In the following examples and comparative examples, the filler is a mixture of talc and powdered quartz in a mass ratio of 2:1; the lubricant is selected from at least one of paraffin wax, PE wax, stearic acid, and calcium stearate; and the antioxidant is antioxidant 1010.

[0032] The preparation method of the chitosan-based high-flame-retardant MPP pipe of the present application comprises the following steps:

[0033] P1. The components are weighed by parts by weight;

[0034] P2. The polypropylene and the chitosan-based flame retardant are mixed uniformly at 70-90℃ to obtain a first mixture; the filler and the lubricant are mixed uniformly at 100-120℃, then the antioxidant is added, and the stirring is continued, then the mixture is kept at 8-10MPa for 5-15min to obtain a second mixture;

[0035] P3. The first mixture and the second mixture are added to a mixer for blending, and the stirring is stopped after heating and stirring to 110-120℃, then the material is cooled to 40-50℃ to obtain a blended material; finally, the blended material is extruded and granulated, and the chitosan-based high-flame-retardant MPP pipe is obtained through molding.

[0036] Example 1

[0037] The present example provides a chitosan-based high-flame-retardant MPP pipe, which comprises the following components by parts by weight: polypropylene 65 parts, filler 17 parts, chitosan-based flame retardant 15 parts, lubricant 2 parts, antioxidant 1 part.

[0038] The preparation method of the chitosan-based flame retardant comprises the following steps:

[0039] S1. The chitosan is placed in a drying oven and dried at 110℃ for 6h to remove the water adsorbed in the raw material, then the dried chitosan is dissolved in a 2% acetic acid solution, the mass ratio of chitosan to 2% acetic acid solution is 1:70, then ultrasonic oscillation is used for dispersion and dissolution, then acetic acid is added dropwise to adjust the pH value of the solution to 4 to obtain solution A;

[0040] S2. The silane coupling agent KH-792 is added to the 2% ethanol aqueous solution with a pH value of 4, the mass ratio of silane coupling agent KH-792 to 2% ethanol aqueous solution is 1:50, then ultrasonic oscillation is used for dispersion and dissolution to obtain solution B;

[0041] S3. Under the protection of nitrogen, solution A and solution B are mixed in a mass ratio of 69:31 to obtain solution C, the mass ratio of chitosan to silane coupling agent KH-792 in solution C is 0.97:0.61; then the solution is stirred rapidly at 50℃ for 3h, then the temperature is increased to 70℃ and the reaction is continued for 0.5h, after the reaction is completed, the product is washed with deionized water and anhydrous ethanol for three times by vacuum filtration, then the obtained filter cake is dried in a vacuum drying oven at 80℃ for 24h; finally, the dried filter cake is ground and sieved through a 200-mesh sieve to obtain the chitosan-based flame retardant.

[0042] The embodiment also provides a preparation method of the chitosan-based high-flame-retardant MPP pipe, comprising the following steps:

[0043] P1. Take each component by weight fraction;

[0044] P2. Put the polypropylene and the chitosan-based flame retardant into a high-speed mixer for stirring and mixing, and after the temperature inside the mixer is increased to 80℃, continue stirring and mixing at a speed of 700 r / min for 40 min to obtain a first mixture; put the filler and the lubricant into a high-speed mixer, increase the temperature to 110℃, and stir and mix for 1 h, then add the antioxidant, continue mixing for 30 min, and then stop stirring, and then heat and press for 10 min at a pressure of 9 MPa to obtain a second mixture;

[0045] P3. Put the first mixture and the second mixture into a mixer for blending, stop stirring after heating and stirring to 120℃, and then cool the material to 50℃ to obtain a blended material; finally, the blended material is extruded and granulated, the temperature of the first zone is set to 180℃, the temperature of the second zone is set to 190℃, the temperature of the third zone is set to 200℃, the temperature of the fourth zone is set to 210℃, the screw rotation speed of the extruder is set to 120 r / min, and finally the chitosan-based high-flame-retardant MPP pipe is formed through a mold.

[0046] Example 2

[0047] The chitosan-based high-flame-retardant MPP pipe of the embodiment is basically the same as that of Example 1, except that:

[0048] The chitosan-based high-flame-retardant MPP pipe of the embodiment comprises the following components by weight fraction: polypropylene 63 parts, filler 17 parts, chitosan-based flame retardant 17 parts, lubricant 2 parts, and antioxidant 1 part.

[0049] Example 3

[0050] The chitosan-based high-flame-retardant MPP pipe of the embodiment is basically the same as that of Example 1, except that:

[0051] The chitosan-based high-flame-retardant MPP pipe of the embodiment comprises the following components by weight fraction: polypropylene 68 parts, filler 17 parts, chitosan-based flame retardant 12 parts, lubricant 2 parts, and antioxidant 1 part.

[0052] Example 4

[0053] The chitosan-based high-flame-retardant MPP pipe of the embodiment is basically the same as that of Example 1, except that:

[0054] The preparation method of the chitosan-based flame retardant of the embodiment comprises the following steps:

[0055] S1 and S2 are the same as in Example 1;

[0056] S3. Under the protection of nitrogen, solution A and solution B were mixed in a mass ratio of 49:51 to obtain solution C, and the mass ratio of chitosan to silane coupling agent KH-792 in solution C was 0.69:1; then the solution was stirred rapidly at 60°C for 2h, and then the temperature was raised to 80°C for continuous reaction for 0.5h; after the reaction was completed, the product was washed with deionized water and anhydrous ethanol three times by vacuum filtration; then the obtained filter cake was placed in a vacuum drying oven at 80°C for drying for 24h; finally, the dried filter cake was ground and sieved through a 200-mesh sieve to obtain the chitosan-based flame retardant.

[0057] Example 5

[0058] The chitosan-based high-flame-retardant MPP pipe of the present example is basically the same as that of Example 1, except that:

[0059] The preparation method of the chitosan-based flame retardant of the present example comprises the following steps:

[0060] S1 and S2 are the same as in Example 1;

[0061] S3. Under the protection of nitrogen, solution A and solution B were mixed in a mass ratio of 49:51 to obtain solution C, and the mass ratio of chitosan to silane coupling agent KH-792 in solution C was 0.69:1; then the solution was stirred rapidly at 60°C for 2h, and then the temperature was raised to 80°C for continuous reaction for 0.5h; after the reaction was completed, the product was washed with deionized water and anhydrous ethanol three times by vacuum filtration; then the obtained filter cake was placed in a vacuum drying oven at 80°C for drying for 24h; finally, the dried filter cake was ground and sieved through a 200-mesh sieve to obtain the chitosan-based flame retardant.

[0062] Comparative Example 1

[0063] The present comparative example provides a MPP pipe comprising the following components in parts by weight: polypropylene 80 parts, filler 17 parts, lubricant 2 parts, antioxidant 1 part; the preparation method of the MPP pipe of the present comparative example is the same as that of Example 1, except that no flame retardant is added in the present comparative example.

[0064] Comparative Example 2

[0065] The chitosan-based high-flame-retardant MPP pipe of the present comparative example is basically the same as that of Example 1, except that:

[0066] The preparation method of the chitosan-based flame retardant of the present comparative example comprises the following steps:

[0067] S1 and S2 are the same as in Example 1;

[0068] S3. Under the protection of nitrogen, solution A and solution B were mixed in a mass ratio of 90:10 to obtain solution C, and the mass ratio of chitosan to silane coupling agent KH-792 in solution C was 1.27:0.2; then the solution was quickly stirred at 50°C for 3h, and then the temperature was increased to 70°C for continuous reaction for 0.5h; after the reaction was completed, the product was washed with deionized water and anhydrous ethanol three times by vacuum filtration; then the obtained filter cake was dried in a vacuum drying oven at 80°C for 24h; finally, the dried filter cake was ground and sieved through a 200-mesh sieve to obtain the chitosan-based flame retardant.

[0069] Comparative Example 3

[0070] The chitosan-based high-flame-retardant MPP pipe material of the present comparative example is basically the same as that of Example 1, except that in the preparation method of the chitosan-based flame retardant, silane coupling agent KH-570 is used instead of KH-792.

[0071] Test Example

[0072] The MPP pipe materials of each example and comparative example were tested for limiting oxygen index and Vicat softening point, and the test results are shown in Table 1.

[0073] The limiting oxygen index (LOI) refers to the lowest oxygen concentration required for a material to burn in a flame under specified conditions in a mixture of oxygen and nitrogen. The higher the LOI value, the better the flame retardant performance. Although the LOI test cannot reflect the large-scale combustion behavior of the material, it has been widely used in industry to evaluate the flame retardant performance of polymer materials. The LOI value is calculated according to the following formula:

[0074]

[0075] In the formula: [O2] - oxygen flow rate, L / min;

[0076] [N2] - nitrogen flow rate, L / min;

[0077] The specific steps are as follows: MPP and flame-retardant MPP composite material are processed into standard test samples (b is about 10mm, h is about 3mm, and l is about 125mm). The LOI value of the sample is determined by an oxygen index tester. The composite material sample is fixed on a combustion rack, the flow rates of N2 and O2 are adjusted to a certain fixed value, the sample is ignited, and it is observed whether the sample can self-extinguish within 3min. If it cannot self-extinguish, the flow rate of N2 is increased, and if it cannot be ignited, the flow rate of O2 is increased. This is repeated until self-extinguishment to determine the limiting oxygen index of the sample.

[0078] The Vicat softening point is tested according to the ISO 306-2022 standard, with a load of 10N and a temperature rise rate of (120±10)℃ / h.

[0079] Table 1 Test results of limiting oxygen index and Vicat softening point of MPP pipes

[0080] Example Limiting oxygen index (%) Vicat softening point (°C) Example 1 45.9 158.1 Example 2 47.3 161.2 Example 3 42.5 153.8 Example 4 44.1 155.6 Example 5 43.6 154.3 Comparative Example 1 20.7 145.2 Comparative Example 2 35.1 149.6 Comparative Example 3 36.4 150.7

[0081] From the data in Table 1, it can be seen that the MPP pipes of the present application have excellent flame retardant and heat resistant properties, the limiting oxygen index is as high as 42.5% or more, and the Vicat softening point is as high as 153.8℃ or more. Among them, the amount of flame retardant is different in Examples 1-3, and by comparison, it can be found that the limiting oxygen index and Vicat softening point of Example 2 are the highest, because the amount of chitosan-based flame retardant in the MPP pipe of Example 2 is more. The mass ratio of chitosan to silane coupling agent KH-792 is different in Examples 1, 4 and 5, and by comparison, it can be found that when the mass ratio of solution A to solution B is 69:31, and the mass ratio of chitosan to silane coupling agent KH-792 is 0.97:0.61 (i.e. Example 1), the limiting oxygen index and Vicat softening point of the MPP pipe are the highest, and the flame retardant and heat resistant properties of the MPP pipe are the best.

[0082] Compared with Example 1, the MPP pipe of Comparative Example 1 does not add flame retardant, and its limiting oxygen index and Vicat softening point are much smaller than those of the MPP pipe using chitosan-based flame retardant of the present application, and the limiting oxygen index of the material prepared in Comparative Example 1 is the lowest; the amount of silane coupling agent in Comparative Example 2 is too low, and the limiting oxygen index and Vicat softening point of the prepared MPP pipe are significantly decreased, and the flame retardant and heat resistant properties of the MPP pipe are significantly reduced; in Comparative Example 3, silane coupling agent KH-570 is selected as the flame retardant, but the flame retardant effect is poorer than that of Example 1, and the flame retardant effect is not ideal.

[0083] Although embodiments of the present application have been shown and described, it is to be understood that for the purpose of the present application, the embodiments change, modify, replace and vary in many ways without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A chitosan-based high flame-retardant MPP pipe material, characterized in that, The components include the following components by weight: polypropylene 63-68 parts, filler 15-20 parts, chitosan-based flame retardant 12-17 parts, lubricant 1-3 parts, antioxidant 0.5-2 parts; The preparation method of the chitosan-based flame retardant comprises the following steps: S1. After drying, the chitosan is dissolved in an acetic acid solution, and then acetic acid is added dropwise to adjust the pH value of the solution to 4 to obtain solution A; S2. The silane coupling agent KH-792 is dissolved in an ethanol aqueous solution to obtain solution B; S3. Under the protection of inert gas, solution A and solution B are mixed to obtain solution C, the mass ratio of chitosan to silane coupling agent KH-792 in solution C is (0.69-1.06):(0.49-1); then the reaction is carried out at 50-60℃ for 2-4h, and then the temperature is increased to 60-80℃ for continuous reaction for 0.5-1h, and then the chitosan-based flame retardant is obtained after separation, washing and drying.

2. The chitosan-based high-flame-retardant MPP pipe according to claim 1, characterized in that, The components include the following components by weight: polypropylene 65 parts, filler 17 parts, chitosan-based flame retardant 15 parts, lubricant 2 parts, antioxidant 1 part.

3. The chitosan-based high-flame-retardant MPP pipe material according to claim 1, characterized in that, In step S3, the mass ratio of chitosan to silane coupling agent KH-792 in solution C is 0.97:0.

61.

4. The chitosan-based high-flame-retardant MPP pipe according to claim 1, characterized in that, The filler includes talcum powder and powdered quartz.

5. The chitosan-based high flame-retardant MPP pipe material according to claim 1, characterized in that, In step S1, the drying temperature is 100-120℃, and the time is 5-7h; the mass percentage of chitosan in solution A is 1-5%.

6. The chitosan-based high flame-retardant MPP pipe material according to claim 1, characterized in that, In step S2, the mass percentage of silane coupling agent KH-792 in solution B is 1.5-5%.

7. The chitosan-based high flame-retardant MPP pipe material according to claim 1, characterized in that, Step S3 further comprises grinding the chitosan-based flame retardant and passing it through a 200-mesh sieve.

8. The chitosan-based high flame-retardant MPP pipe material according to claim 1, characterized in that, The lubricant includes at least one of paraffin wax, PE wax, stearic acid, and calcium stearate; and the antioxidant is a hindered phenolic antioxidant and / or a phosphite antioxidant.

9. The method for preparing the high flame-retardant MPP pipe material based on chitosan according to any one of claims 1-8, characterized in that, The method comprises the following steps: P1. The components are weighed by weight fraction; P2. The polypropylene and the chitosan-based flame retardant are uniformly mixed at 70-90℃ to obtain a first mixture; the filler and the lubricant are uniformly mixed at 100-120℃, and then the antioxidant is added, and the stirring is continued, and then the temperature and pressure are maintained at 8-10MPa for 5-15min to obtain a second mixture; P3. The first mixture and the second mixture are added to a mixing machine for blending, and the stirring is stopped after heating and stirring to 110-120℃, and then the material is cooled to 40-50℃ to obtain a blended material; finally, the blended material is extruded and granulated, and the chitosan-based high-flame-retardant MPP pipe is formed through a mold.

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