A modified biomass-based MPP pipe and preparation method thereof

Abstract

The invention discloses a modified biomass-based MPP pipe, which belongs to the technical field of flame-retardant pipes. The modified biomass-based MPP pipe comprises, by weight, 63 to 70 parts of polypropylene, 12 to 17 parts of filler, 10 to 17 parts of modified chitosan quaternary ammonium salt powder, 1 to 3 parts of lubricant and 1 to 2 parts of antioxidant; the modified chitosan quaternary ammonium salt powder is obtained by grafting diethylenetriaminopropyltrimethoxysilane with chitosan quaternary ammonium salt. During the preparation process of the MPP pipe of the present invention, chitosan quaternary ammonium salt modified by silane coupling agent KH‑892 is added to improve the flame retardant performance of the MPP pipe.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant pipes, and in particular to a modified biomass-based MPP pipe and a preparation method thereof. Background Art

[0002] MPP pipes are generally divided into two types: trenchless and trenchless. MPP trenchless pipes, also known as MPP jacking pipes or dragging pipes, use modified polypropylene (MPP) as the main raw material. With the gradual expansion of the application fields and environments of MPP pipes, their shortcomings have become increasingly prominent. For example, its flame retardancy and other properties cannot fully adapt to high-demand environments. In high-temperature environments, a large amount of heat energy will accumulate due to power transmission, which is prone to flammability, causing certain inconveniences in the use of MPP pipes. Therefore, it is urgent to improve its flame retardant properties.

[0003] Chitosan quaternary ammonium salt is a high-grade chitosan derivative obtained by chemically modifying marine chitosan. It belongs to a natural bio-adjuvant product with good biodegradability and biocompatibility. Chitosan quaternary ammonium salt has a large amount of carbon source and nitrogen source. During the combustion process, it can be carbonized in the polymer to hinder the combustion, promote the formation of an expanded carbon layer, and help to inhibit the heat exchange in the matrix. However, the number of hydroxyl and amino groups in chitosan quaternary ammonium salt is too much, has certain hydrophilic and oleophobic properties, and has poor compatibility with polypropylene (PP), so it is necessary to modify chitosan quaternary ammonium salt to give play to excellent flame retardant properties.

[0004] In view of the above problems, it is of great significance to develop a modified biomass-based MPP pipe with high flame retardant properties using modified chitosan quaternary ammonium salt. Summary of the invention

[0005] In view of the deficiencies of the above prior art, the present invention provides a modified biomass-based MPP pipe and a preparation method thereof. During the preparation of the MPP pipe, chitosan quaternary ammonium salt modified by silane coupling agent KH-892 is added to improve the flame retardant properties of the MPP pipe, which is specifically achieved through the following technologies.

[0006] The present invention provides a modified biomass-based MPP pipe, which comprises, by weight, 63 to 70 parts of polypropylene, 12 to 17 parts of filler, 10 to 17 parts of modified chitosan quaternary ammonium salt powder, 1 to 3 parts of lubricant and 1 to 2 parts of antioxidant;

[0007] The modified chitosan quaternary ammonium salt powder is obtained by grafting diethylenetriaminopropyltrimethoxysilane (KH-892) onto chitosan quaternary ammonium salt.

[0008] The present invention uses a silane coupling agent KH-892 (diethylenetriaminopropyltrimethoxysilane), which has rich carbon sources, nitrogen sources and silicon sources. On the one hand, the amount of carbon in the modified chitosan quaternary ammonium salt is increased, and a silicon source is additionally introduced. Through the action of the condensed phase, a carbon layer is formed to prevent the polymer material from being exposed to the flame and limit the further diffusion of oxygen in the air to the material matrix, thereby achieving the effect of interrupting the combustion of the polymer; on the other hand, KH-892 further increases the amount of nitrogen source in the flame retardant. When heated or burned, the amino group is generated in the form of NH3 gas, which dilutes the polymer. The concentration of oxygen and gaseous combustible products on the surface of the composite is reduced, and after the system is gelled and solidified, it promotes the formation of a microporous expanded carbon layer, which has a better protective effect on the matrix, thereby further improving the flame retardant properties of chitosan quaternary ammonium salt; thirdly, the addition of a silicon source to the modified chitosan quaternary ammonium salt can achieve flame retardancy through a condensation phase mechanism, and form a solid phase coating containing Si-C on the surface of the polymer matrix, which has a high temperature resistance effect. Under the joint action of chitosan quaternary ammonium salt and KH-892, the application of chitosan quaternary ammonium salt-based flame retardant in MPP pipes has been better reflected, thereby improving the flame retardant properties of MPP pipes.

[0009] Preferably, the filler is a mixture of talc and powdered quartz.

[0010] Preferably, the lubricant is at least one of calcium stearate, methyl stearate or butyl stearate.

[0011] Preferably, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

[0012] Preferably, the preparation method of the modified chitosan quaternary ammonium salt powder comprises the following steps:

[0013] P1, drying chitosan quaternary ammonium salt, dissolving it in acetic acid solution, adjusting the pH value to acidic, to obtain solution A; dissolving diethylenetriaminopropyltrimethoxysilane in acetic acid solution, to obtain solution B;

[0014] P2. Under the protection of inert gas, solution A and solution B are mixed to obtain solution C, which is then heated, stirred, filtered under reduced pressure, washed, dried, crushed, ground, and sieved to obtain modified chitosan quaternary ammonium salt powder.

[0015] The invention adopts chitosan quaternary ammonium salt as a raw material, which has a wide source and a low price, and then a silane coupling agent (diethylenetriaminopropyltrimethoxysilane, KH-892) is acted on the chitosan quaternary ammonium salt to obtain a chitosan quaternary ammonium salt grafted silane coupling agent composite material. After the composite material is acted on an MPP pipe, high flame retardant performance can be obtained. The method of the invention can not only solve the problem of normal use of subsequent MPP pipes, but also reduce the cost of flame retardants, which meets the use requirements of power technology.

[0016] Preferably, the mass percentage of chitosan quaternary ammonium salt in solution A is 1 to 1.5%.

[0017] Preferably, the mass percentage of diethylenetriaminopropyltrimethoxysilane in solution B is 1.5-2%.

[0018] Preferably, the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in solution C is (7-11.5):(4-10). Further preferably, the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in solution C is 9.15:6.86.

[0019] Preferably, in step P1, the drying temperature is 100-120° C., and the drying time is 5-8 hours.

[0020] Preferably, the pH values ​​of solution A and solution B in step P1 are both 3-6.

[0021] Preferably, the heating and stirring in step P2 are divided into two stages. The first stage is heating to 40-60° C. and stirring time is 2-4 h; the second stage is heating to 60-80° C. and stirring time is 0.5-1 h.

[0022] Preferably, in step P2, the drying temperature is 60-80° C. and the drying time is 24-30 hours.

[0023] Preferably, the inert gas in step P2 is nitrogen or argon.

[0024] The method for preparing any one of the above modified biomass-based MPP pipes comprises the following steps:

[0025] S1, polypropylene and modified chitosan quaternary ammonium salt powder are stirred and mixed, and stirring and mixing are continued at temperature I to obtain mixture I; filler and lubricant are mixed, stirred and mixed at temperature II, antioxidant is added, stirring and mixing are continued, heat preservation, pressure maintenance, to obtain mixture II;

[0026] S2, stirring and mixing mixture I and mixture II, heating to temperature III, stopping stirring, and cooling to obtain mixture III;

[0027] S3, extruding and granulating the mixture III, and then thermoplasticizing and molding it through a mold to obtain an MPP pipe.

[0028] Preferably, in step S1, temperature I is 70-90°C; temperature II is 100-120°C.

[0029] Preferably, the pressure of the pressure-maintaining step S1 is 8 to 11 MPa, and the pressure-maintaining time is 8 to 16 minutes.

[0030] Preferably, in step S2, the mass ratio of mixture I to mixture II is 1:(1-2).

[0031] Preferably, the temperature III in step S2 is 110-130°C.

[0032] Compared with the prior art, the present invention is beneficial in that:

[0033] 1. The present invention adopts silane coupling agent diethylenetriaminopropyltrimethoxysilane (KH-892) to graft and modify chitosan quaternary ammonium salt, which can not only improve the flame retardant properties of chitosan quaternary ammonium salt, but also improve the disadvantage of poor organic compatibility of chitosan quaternary ammonium salt;

[0034] 2. The MPP pipe of the present invention has high flame retardancy, a limiting oxygen index exceeding 42%, a Vicat softening point temperature above 154°C, and excellent flame retardancy.

[0035] 3. Chitosan quaternary ammonium salt is a derivative of common chitosan and a natural bio-auxiliary product. With the increasing prominence of environmental resource issues, the understanding of chitosan quaternary ammonium salt has gradually deepened, and how to use it has received more and more attention. The flame retardant material prepared with chitosan quaternary ammonium salt as raw material can not only produce low-smoke and low-toxic flame retardants, but also expand the application field of chitosan quaternary ammonium salt. It is of great significance to the effective utilization of biomass-based materials in my country and the significant improvement of the ecological environment. DETAILED DESCRIPTION

[0036] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0037] A modified biomass-based MPP pipe comprises, by weight, 63 to 70 parts of polypropylene, 12 to 17 parts of filler, 10 to 17 parts of modified chitosan quaternary ammonium salt powder, 1 to 3 parts of lubricant and 1 to 2 parts of antioxidant;

[0038] Wherein, the modified chitosan quaternary ammonium salt powder is obtained by grafting diethylenetriaminopropyltrimethoxysilane (KH-892) onto chitosan quaternary ammonium salt;

[0039] Optionally, the filler is a mixture of talcum powder and powdered quartz, and the mass ratio of talcum powder to powdered quartz is 2:1;

[0040] Optionally, the lubricant is at least one of calcium stearate, methyl stearate or butyl stearate;

[0041] Optionally, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant. Further preferably, the antioxidant is antioxidant 1010;

[0042] Wherein, the preparation method of the above-mentioned modified chitosan quaternary ammonium salt powder comprises the following steps:

[0043] P1. Dry chitosan quaternary ammonium salt at 100-120° C. for 5-8 hours, and dissolve it in acetic acid solution, wherein the mass ratio of chitosan quaternary ammonium salt to acetic acid is 1:70, to obtain solution A, wherein the mass percentage of chitosan quaternary ammonium salt in solution A is 1.41%; add diethylenetriaminopropyltrimethoxysilane (KH-892) to acetic acid solution and dissolve it, wherein the mass ratio of diethylenetriaminopropyltrimethoxysilane (KH-892) to acetic acid solution is 1:50, to obtain solution B, wherein the mass percentage of diethylenetriaminopropyltrimethoxysilane (KH-892) in solution B is 1.96%; the pH values ​​of solution A and solution B are both 3-6;

[0044] P2. Under nitrogen or argon protection, solution A and solution B are mixed in a mass ratio of (51-79):(21-49) to obtain solution C, in which the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane is (7-11.5):(4-10). The solution is heated to 40-60°C, stirred for 2-4 hours, then heated to 60-80°C, and the reaction is continued with stirring for 0.5-1 hour. The solution is filtered under reduced pressure, washed, dried at 60-80°C for 24-30 hours, crushed, ground, and sieved to obtain modified chitosan quaternary ammonium salt powder.

[0045] The method for preparing a modified biomass-based MPP pipe using the modified chitosan quaternary ammonium salt powder comprises the following steps:

[0046] S1, mixing polypropylene and modified chitosan quaternary ammonium salt powder, placing at 70-90° C. and continuing to stir and mix, to obtain mixture I; mixing filler and lubricant, placing at 100-120° C. and stirring and mixing evenly, adding antioxidant, continuing to stir and mix, keeping warm, and maintaining pressure at a pressure of 8-11 MPa for 8-16 min to obtain mixture II;

[0047] S2, mixing mixture I and mixture II at a mass ratio of 1:(1-2), heating to 110-130° C., stopping stirring, and cooling to obtain mixture III;

[0048] S3, extruding and granulating the mixture III, and then thermoplasticizing and molding it through a mold to obtain an MPP pipe.

[0049] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Example 1

[0051] This embodiment provides a modified biomass-based MPP pipe, which includes, by weight, 66 parts of polypropylene, 14 parts of modified chitosan quaternary ammonium salt powder, 17 parts of a mixture of talc and powdered quartz, 2 parts of calcium stearate, and 1 part of an antioxidant 1010;

[0052] Wherein, the preparation method of modified chitosan quaternary ammonium salt powder comprises the following steps:

[0053] P1. Dry chitosan quaternary ammonium salt at 110° C. for 6 h, dissolve it in 2% acetic acid solution, the mass ratio of chitosan quaternary ammonium salt to acetic acid solution is 1:70, and obtain solution A; add diethylenetriaminopropyltrimethoxysilane (KH-892) to 2% acetic acid solution and dissolve it, the mass ratio of diethylenetriaminopropyltrimethoxysilane (KH-892) to acetic acid solution is 1:50, and obtain solution B; the pH values ​​of solution A and solution B are both 4;

[0054] P2. Under nitrogen protection, solution A and solution B were mixed in a mass ratio of 65:35 to obtain solution C, in which the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in solution C was 9.15:6.86. The mixture was heated to 50°C and rapidly stirred for 3 hours. The mixture was then heated to 70°C and stirred for 0.5 hours. After reduced pressure filtration, the chitosan quaternary ammonium salt grafted diethylenetriaminopropyltrimethoxysilane (KH-892) slurry was washed three times with deionized water and anhydrous ethanol, respectively. The filter cake was then placed in a vacuum drying oven at 80°C and dried for 24 hours. The dried filter cake was crushed, ground, and sieved through a 200-mesh sieve to obtain modified chitosan quaternary ammonium salt powder.

[0055] This embodiment also provides a method for preparing a modified biomass-based MPP pipe using the modified chitosan quaternary ammonium salt powder, comprising the following steps:

[0056] S1, polypropylene and modified chitosan quaternary ammonium salt powder are placed in a high-speed mixer and stirred and mixed, the stirring speed is set to 700r / min, and then placed at 80°C and stirred and mixed for 40min to obtain a mixture I; a mixture of talcum powder and powdered quartz and calcium stearate are stirred and mixed, placed at 110°C and stirred and mixed evenly, and then antioxidant 1010 is added, and stirring and mixing is continued for 30min, and the mixture is kept warm and maintained at a pressure of 9MPa for 10min to obtain a mixture II;

[0057] S2, mixing mixture I and mixture II at a mass ratio of 1:1, heating to 120° C. and then stopping stirring, and cooling to 50° C. to obtain mixture III;

[0058] S3. Extruding and granulating the mixture III through a twin-screw extruder, and then thermoplasticizing and molding the mixture through a mold to obtain an MPP pipe; wherein the temperature of the barrel zone 1 is set to 180°C, the temperature of the zone 2 is set to 190°C, the temperature of the zone 3 is set to 200°C, the temperature of the zone 4 is set to 210°C, and the screw speed of the extruder is set to 120r / min.

[0059] Example 2

[0060] This embodiment provides a modified biomass-based MPP pipe, which includes, by weight, 70 parts of polypropylene, 10 parts of modified chitosan quaternary ammonium salt powder, 17 parts of a mixture of talc and powdered quartz, 2 parts of calcium stearate, and 1 part of an antioxidant 1010;

[0061] Wherein, the preparation method of modified chitosan quaternary ammonium salt powder comprises the following steps:

[0062] P1. Dry chitosan quaternary ammonium salt at 110° C. for 8 h, dissolve it in 2% acetic acid solution, the mass ratio of chitosan quaternary ammonium salt to acetic acid solution is 1:70, and obtain solution A; add diethylenetriaminopropyltrimethoxysilane (KH-892) to 2% acetic acid solution and dissolve it, the mass ratio of diethylenetriaminopropyltrimethoxysilane (KH-892) to acetic acid solution is 1:50, and obtain solution B; the pH values ​​of solution A and solution B are both 4;

[0063] P2. Under nitrogen protection, solution A and solution B were mixed in a mass ratio of 65:35 to obtain solution C, in which the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in solution C was 9.15:6.86. The mixture was heated to 40°C and rapidly stirred for 4 hours. The mixture was then heated to 80°C and stirred for 1 hour. After reduced pressure filtration, the chitosan quaternary ammonium salt grafted diethylenetriaminopropyltrimethoxysilane (KH-892) slurry was washed three times with deionized water and anhydrous ethanol, respectively. The filter cake was then placed in a vacuum drying oven at 80°C and dried for 28 hours. The dried filter cake was crushed, ground, and sieved through a 200-mesh sieve to obtain modified chitosan quaternary ammonium salt powder.

[0064] This embodiment also provides a method for preparing a modified biomass-based MPP pipe using the modified chitosan quaternary ammonium salt powder, comprising the following steps:

[0065] S1, polypropylene and modified chitosan quaternary ammonium salt powder are placed in a high-speed mixer and stirred and mixed, the stirring speed is set to 700r / min, and then placed at 90°C and stirred and mixed for 40min to obtain a mixture I; a mixture of talcum powder and powdered quartz and calcium stearate are stirred and mixed, placed at 100°C and stirred and mixed uniformly, and then an antioxidant 1010 is added, and stirring and mixing is continued for 30min, and the mixture is kept warm and maintained at a pressure of 11MPa for 16min to obtain a mixture II;

[0066] S2, mixing mixture I and mixture II at a mass ratio of 1:1, heating to 110° C. and then stopping stirring, and cooling to 50° C. to obtain mixture III;

[0067] S3. Extruding and granulating the mixture III through a twin-screw extruder, and then thermoplasticizing and molding the mixture through a mold to obtain an MPP pipe; wherein the temperature of the barrel zone 1 is set to 180°C, the temperature of the zone 2 is set to 190°C, the temperature of the zone 3 is set to 200°C, the temperature of the zone 4 is set to 210°C, and the screw speed of the extruder is set to 120r / min.

[0068] Example 3

[0069] This embodiment provides a modified biomass-based MPP pipe, which includes, by weight, 63 parts of polypropylene, 17 parts of modified chitosan quaternary ammonium salt powder, 17 parts of a mixture of talc and powdered quartz, 2 parts of calcium stearate, and 1 part of an antioxidant 1010;

[0070] Wherein, the preparation method of modified chitosan quaternary ammonium salt powder comprises the following steps:

[0071] P1. Dry chitosan quaternary ammonium salt at 120°C for 5h, dissolve it in 2% acetic acid solution, the mass ratio of chitosan quaternary ammonium salt to acetic acid solution is 1:70, and obtain solution A; add diethylenetriaminopropyltrimethoxysilane (KH-892) to 2% acetic acid solution and dissolve it, the mass ratio of diethylenetriaminopropyltrimethoxysilane (KH-892) to acetic acid solution is 1:50, and obtain solution B; the pH values ​​of solution A and solution B are both 4;

[0072] P2. Under nitrogen protection, solution A and solution B were mixed in a mass ratio of 65:35 to obtain solution C, in which the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in solution C was 9.15:6.86. The mixture was heated to 60°C and rapidly stirred for 2 hours. The mixture was then heated to 60°C and stirred for 1 hour. After vacuum filtration, the chitosan quaternary ammonium salt grafted diethylenetriaminopropyltrimethoxysilane (KH-892) slurry was washed three times with deionized water and anhydrous ethanol, respectively. The filter cake was then placed in a vacuum drying oven at 60°C and dried for 30 hours. The dried filter cake was crushed, ground, and sieved through a 200-mesh sieve to obtain modified chitosan quaternary ammonium salt powder.

[0073] This embodiment also provides a method for preparing a modified biomass-based MPP pipe using the modified chitosan quaternary ammonium salt powder, comprising the following steps:

[0074] S1, polypropylene and modified chitosan quaternary ammonium salt powder are placed in a high-speed mixer and stirred and mixed, the stirring speed is set to 700r / min, and then placed at 70°C and stirred and mixed for 40min to obtain a mixture I; a mixture of talcum powder and powdered quartz and calcium stearate are stirred and mixed, placed at 120°C and stirred and mixed evenly, and then antioxidant 1010 is added, and stirring and mixing is continued for 30min, and the mixture is kept warm and maintained at a pressure of 8MPa for 8min to obtain a mixture II;

[0075] S2, mixing mixture I and mixture II at a mass ratio of 1:1, heating to 130° C. and then stopping stirring, and cooling to 50° C. to obtain mixture III;

[0076] S3. Extruding and granulating the mixture III through a twin-screw extruder, and then thermoplasticizing and molding the mixture through a mold to obtain an MPP pipe; wherein the temperature of the barrel zone 1 is set to 180°C, the temperature of the zone 2 is set to 190°C, the temperature of the zone 3 is set to 200°C, the temperature of the zone 4 is set to 210°C, and the screw speed of the extruder is set to 120r / min.

[0077] Example 4

[0078] This embodiment is basically the same as Example 1, except that in step P2 of the method for preparing the modified chitosan quaternary ammonium salt powder, solution A and solution B are mixed in a mass ratio of 51:49 to obtain solution C, and the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in solution C is 7.18:9.61.

[0079] Example 5

[0080] This embodiment is substantially the same as Embodiment 1, except that in step P2 of the method for preparing the modified chitosan quaternary ammonium salt powder, solution A and solution B are mixed in a mass ratio of 79:21 to obtain solution C, in which the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane is 11.13:4.12.

[0081] Comparative Example 1

[0082] This comparative example is basically the same as Example 1, except that the manufacturing material of the modified biomass-based MPP pipe does not include modified chitosan quaternary ammonium salt powder, that is, the manufacturing material of the modified biomass-based MPP pipe provided in this comparative example includes the following weight components:

[0083] 80 parts of polypropylene, 17 parts of a mixture of talc and powdered quartz, 2 parts of calcium stearate and 1 part of antioxidant 1010.

[0084] Comparative Example 2

[0085] This comparative example is basically the same as Example 1, except that in step P2 of the preparation method of the modified chitosan quaternary ammonium salt powder, solution A and solution B are mixed in a mass ratio of 91:9 to obtain solution C, and the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in solution C is 12.82:1.76.

[0086] Comparative Example 3

[0087] This comparative example is substantially the same as Example 1, except that the silane coupling agent KH-892 is replaced by an equal mass of silane coupling agent KH-570.

[0088] Application Example 1

[0089] Limiting oxygen index test

[0090] The limiting oxygen index (LOI) refers to the minimum oxygen concentration required for a material to burn with a flame in a mixed gas flow of oxygen and nitrogen under specified conditions. 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 properties of polymer materials. The LOI value is calculated according to the following formula:

[0091]

[0092] Where: [O2] represents the oxygen flow rate, in L / min; [N2] represents the nitrogen flow rate, in L / min.

[0093] The specific steps are as follows: The MPP pipes in Examples 1 to 5 and Comparative Examples 1 to 3 are processed into standard test specimens (width b is about 10 mm, height h is about 3 mm, and length l is about 125 mm). The LOI value of the specimen is measured by an oxygen index meter, the specimen to be tested is fixed on a combustion rack, the flow rates of N2 and O2 are adjusted to a certain fixed value, the specimen to be tested is ignited, and it is observed whether the specimen to be tested can self-extinguish within 3 minutes. 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. Repeat the test until it self-extinguishes to determine the limiting oxygen index of the specimen. The test results are shown in Table 1.

[0094] Application Example 2

[0095] Vicat softening point test

[0096] The MPP pipes of Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to a Vicat softening point test according to ISO 306-2022 standard to obtain the temperature at which the MPP pipes of Examples 1 to 5 and Comparative Examples 1 to 3 began to soften rapidly, wherein the load gravity was 10N and the heating rate was (120±10)°C / h. The test results are shown in Table 1.

[0097] Table 1 Test results of Examples 1 to 5 and Comparative Examples 1 to 3

[0098]

[0099]

[0100] As can be seen from Table 1, the limiting oxygen index of Examples 1 to 5 all exceeds 42%, and the Vicat softening point temperatures are all above 154° C., which indicates that the MPP pipe to which the modified chitosan quaternary ammonium salt powder of the present invention is added has excellent flame retardant properties, and the limiting oxygen index and Vicat softening point of Example 3 are the highest, which is due to the fact that the number of modified chitosan quaternary ammonium salt added to the MPP pipe of Example 3 is relatively large.

[0101] The limiting oxygen index and Vicat softening point of Examples 1 to 3 are better than those of Examples 4 to 5. This is because the difference between Examples 1 to 3 and Examples 4 to 5 is that the mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane is 9.15:6.86, so the prepared MPP pipe has excellent flame retardant properties; and even if the amount of modified chitosan quaternary ammonium salt added to the MPP pipe of Example 2 is small, the flame retardant properties are still better than those of Examples 4 to 5.

[0102] Compared with Example 1, the limiting oxygen index and Vicat softening point of Comparative Example 1 are significantly reduced. This is because the solution adopted in Comparative Example 1 is not to add flame retardant, so the flame retardant performance of the prepared MPP pipe is poor.

[0103] Compared with Example 1, the limiting oxygen index and Vicat softening point of Comparative Example 2 are improved, but compared with Example 1, the limiting oxygen index and Vicat softening point are still significantly reduced. This is because the amount of silane coupling agent used in Comparative Example 2 is relatively small, so the prepared MPP pipe has certain heat resistance, but the flame retardant performance is not ideal.

[0104] Compared with Example 1, the limiting oxygen index and Vicat softening point of Comparative Example 3 are improved, but compared with Example 1, the limiting oxygen index and Vicat softening point are still significantly reduced. This is because KH-570 is used in Comparative Example 3 to graft and modify carboxymethyl chitosan, and the modified flame retardant obtained has poor flame retardant effect, so the flame retardant performance of the prepared MMP pipe is general.

[0105] The above specific embodiments describe the implementation of the present invention in detail, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, the technical solution of the present invention can be modified and changed in many simple ways, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A modified biomass-based MPP pipe, characterized in that: The invention comprises, by weight, 63 to 70 parts of polypropylene, 12 to 17 parts of filler, 10 to 17 parts of modified chitosan quaternary ammonium salt powder, 1 to 3 parts of lubricant and 1 to 2 parts of antioxidant; Wherein, the preparation method of the modified chitosan quaternary ammonium salt powder comprises the following steps: P1, drying chitosan quaternary ammonium salt, dissolving it in acetic acid solution, adjusting the pH value to acidic, to obtain solution A; dissolving diethylenetriaminopropyltrimethoxysilane in acetic acid solution, to obtain solution B; P2. Under the protection of inert gas, solution A and solution B are mixed to obtain solution C, which is then heated, stirred, filtered under reduced pressure, washed, dried, crushed, ground, and sieved to obtain modified chitosan quaternary ammonium salt powder. The mass ratio of chitosan quaternary ammonium salt to diethylenetriaminopropyltrimethoxysilane in the solution C is (7-11.5):(4-10).

2. The modified biomass-based MPP pipe according to claim 1, characterized in that: The filler is a mixture of talcum powder and powdered quartz.

3. The modified biomass-based MPP pipe according to claim 1, characterized in that: The lubricant is at least one of calcium stearate, methyl stearate or butyl stearate.

4. The modified biomass-based MPP pipe according to claim 1, characterized in that: The antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

5. The modified biomass-based MPP pipe according to claim 1, characterized in that: The pH values ​​of the solution A and the solution B in step P1 are both 3-6.

6. The modified biomass-based MPP pipe according to claim 1, characterized in that: In step P2, the heating and stirring are divided into two stages. In the first stage, the mixture is heated to 40-60° C. and stirred for 2-4 hours. In the second stage, the mixture is heated to 60-80° C. and stirred for 0.5-1 hour.

7. The method for preparing a modified biomass-based MPP pipe according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, polypropylene and modified chitosan quaternary ammonium salt powder are stirred and mixed, and stirring and mixing are continued at temperature I to obtain mixture I; filler and lubricant are mixed, stirred and mixed at temperature II, antioxidant is added, stirring and mixing are continued, heat preservation, pressure maintenance, to obtain mixture II; S2, stirring and mixing mixture I and mixture II, heating to temperature III, stopping stirring, and cooling to obtain mixture III; S3, extruding and granulating the mixture III, and then thermoplasticizing and molding it through a mold to obtain an MPP pipe.

8. The method for preparing modified biomass-based MPP pipe according to claim 7, characterized in that: In step S2, the mass ratio of the mixture I to the mixture II is 1:(1-2).

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