Processing method of high-toughness HDPE (High-Density Polyethylene) siphon drainage pipe material

Abstract

The invention belongs to the technical field of plastic pipes, and particularly relates to a processing method of a high-toughness HDPE siphon drainage pipe. According to the processing method of the high-toughness HDPE siphon drainage pipe material, a three-layer structure design is adopted, the modified wood fiber filler is subjected to secondary modification, a hydrophobic interface layer is constructed, the modified wood fiber filler and matrix plastic are combined more tightly, the toughness and strength of modified wood fiber reinforced particles are enhanced, and the service life of the material is prolonged. And the modified wood fiber reinforced particles are added into the core layer for blending modification, so that the heat resistance and mechanical properties of the pipe are improved, and the adhesive force of the core layer to the inner and outer layers can be enhanced. The halogen-free flame retardant obtained by compounding modified magnesium aluminum hydrotalcite, octyl diphenyl phosphate and triphenyl phosphate can endow the outer layer with excellent flame retardant property, and does not generate toxic and harmful halogen gas in the combustion process, thereby meeting the environmental protection requirement. The HDPE siphon drainage pipe material prepared by the invention has excellent antistatic, flame-retardant, anti-aging, corrosion-resistant and mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic pipes, and in particular relates to a processing method for a high-toughness HDPE siphon drainage pipe. Background Art

[0002] High-density polyethylene (HDPE) is a highly crystalline, non-polar thermoplastic resin generated by ethylene copolymerization. It is inexpensive, non-toxic and tasteless, and has good wear resistance, cold resistance and chemical stability. Compared with low-density polyethylene (LDPE), HDPE has lower permeability to water vapor and air and better corrosion resistance, so it is one of the most commonly used materials for drainage pipes. However, HDPE has poor aging resistance and has disadvantages such as easy deformation, aging, brittleness and stress cracking. Therefore, the modification of HDPE such as enhancement, toughening and heat resistance is one of the important directions for research and development of new engineering plastics at home and abroad.

[0003] Existing HDPE drainage pipes usually include an inner layer, a core layer, and an outer layer. The outer layer uses ultra-high molecular weight polyethylene, and graphene is used as a coloring carrier for modified masterbatch to improve the wear resistance of the drainage pipe and improve the pipe's ability to resist external pressure.

[0004] However, during the manufacturing of drainage pipes with this structure, there are still problems such as uneven dispersion of fillers and insufficient improvement in flame retardancy, which makes the final HDPE drainage pipe unable to have both high toughness and good flame retardancy. Summary of the invention

[0005] The purpose of the present invention is to provide a processing method for high-toughness HDPE siphon drainage pipes, which is used to solve the technical problems in the prior art that fillers are easily unevenly dispersed and the flame retardant properties of HDPE drainage pipes are not sufficiently improved, making it impossible for HDPE drainage pipes to have both high toughness and good flame retardant properties.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for processing a high-toughness HDPE siphon drainage pipe comprises the following steps:

[0008] S10, adding the raw materials of the inner layer, the core layer and the outer layer into a high-speed mixer respectively to obtain a mixture A, a mixture B and a mixture C;

[0009] S20, adding the three mixed materials into a three-layer co-extrusion die in sequence, and composite extruding and molding to obtain an unshaped pipe;

[0010] S30, placing the unshaped pipe into a cooling water tank for cooling to obtain a high-toughness HDPE siphon drainage pipe.

[0011] The high-toughness HDPE siphon drainage pipe comprises an inner layer, a core layer and an outer layer which are sequentially arranged from the inside to the outside.

[0012] The inner layer is prepared from the following components in parts by weight: 80-94 parts of high-density polyethylene, 1-5 parts of antistatic agent, 5-15 parts of thermoplastic vulcanized rubber, 0.5-2 parts of antioxidant and 1-5 parts of lubricant;

[0013] The core layer is prepared from the following components in parts by weight: 75-90 parts of high-density polyethylene, 10-25 parts of modified wood fiber reinforcement particles and 1-5 parts of lubricant;

[0014] The outer layer is prepared from the following components in parts by weight: 91-98.5 parts of high-density polyethylene, 0.5-2 parts of halogen-free flame retardant, 0.5-2 parts of antioxidant, 0.5-5 parts of fumed silica and 1-5 parts of lubricant.

[0015] Preferably, the antistatic agent is any one of hexadecyl sulfonate, monoglyceride and HIPS antistatic agent.

[0016] Preferably, the thermoplastic vulcanized rubber is a thermoplastic vulcanized rubber composed of polypropylene / ethylene propylene diene monomer rubber, and preferably a thermoplastic vulcanized rubber in which polypropylene and ethylene propylene diene monomer rubber are mixed in a mass ratio of 3:7.

[0017] Preferably, the antioxidants in the inner layer and the outer layer are one or more combinations of 168, 1010, 1098 and 1076.

[0018] Preferably, the lubricants of the inner layer, the core layer and the outer layer are all one or more combinations of sodium stearate, zinc stearate and polyethylene wax.

[0019] Preferably, the method for preparing modified wood fiber reinforced particles comprises the following steps:

[0020] S11, putting fumed silica, modified wood fiber filler, polypropylene, maleic anhydride grafted polypropylene and lubricant into a high-speed mixer and stirring and blending for 10 to 15 minutes to obtain feed;

[0021] S12, adding the feed material into the twin-rod extruder for melt extrusion, and placing the melt into a water tank for cooling for 30 to 60 minutes;

[0022] S13, placing the cooled melt into a pelletizer to pelletize to obtain modified wood fiber reinforced particles.

[0023] Preferably, the method for preparing the modified wood fiber filler comprises the following steps:

[0024] S21, placing the stick-shaped wood fibers in an oven for pre-drying, and spreading them on a flat plate after drying;

[0025] S22, adding a solvent into two reaction kettles, adding a catalyst and phenyl hydrogen siloxane into one of the reaction kettles at room temperature to obtain a primary modified solution, and heating the other reaction kettle to 50-60° C., adding an unsaturated rubber into the solvent, and continuously stirring until the unsaturated rubber is completely dissolved to obtain a secondary modified solution;

[0026] S23, spraying the primary modified solution evenly on the surface of the rod-shaped wood fiber and continuously stirring the rod-shaped wood fiber, reacting at room temperature for 20 to 40 minutes, and after the reaction is completed, drying to remove the solvent to obtain modified rod-shaped wood fiber;

[0027] S24, adding the modified rod-shaped wood fiber into the secondary modification solution, reacting for 1 to 3 minutes under stirring, and filtering and drying after the reaction to obtain the modified wood fiber filler.

[0028] Preferably, the lubricant in step S11 is any one of sodium stearate, zinc stearate and polyethylene wax.

[0029] Preferably, the weight parts of the components in step S11 are 1-5 parts of fumed silica, 15-30 parts of modified wood fiber filler, 70-85 parts of polypropylene, 5-10 parts of maleic anhydride grafted polypropylene and 1-5 parts of lubricant.

[0030] Preferably, the rotation speed of the high-speed mixer in step S11 is 150-200 rpm.

[0031] Preferably, in step S12, the feed port temperature of the twin-rod extruder is 160-180°C, and the extrusion temperature is 190-210°C.

[0032] Preferably, the temperature of the cooling water in the water tank in step S12 is 10-30°C.

[0033] Preferably, in step S21, the rod-shaped wood fiber is any one of bamboo fiber, straw fiber and rice husk fiber, with a specification of 30-40 meshes, and the weight portion of wood powder is 50 parts.

[0034] Preferably, the oven temperature for the pre-drying treatment in step S21 is set to 100-105° C., and the drying time is 12-18 hours.

[0035] Preferably, the catalyst in step S22 is a platinum-containing catalyst, preferably a Castel catalyst.

[0036] Preferably, the phenyl hydrogen-containing siloxane in step S22 is a hydrogen-containing siloxane with a low phenyl content.

[0037] Preferably, the solvent in step S22 is any one of n-hexane, toluene, n-heptane and n-propanol.

[0038] Preferably, the unsaturated rubber in step S22 is any one of nitrile rubber, EPDM rubber and isoprene rubber.

[0039] Preferably, in step S22, the weight parts of each substance used to prepare the primary modified solution are 0.01-0.05 parts of catalyst, 0.5-1 parts of phenyl hydrogen siloxane and 10-20 parts of solvent, and the weight parts of each substance used to prepare the secondary modified solution are 1-3 parts of unsaturated rubber and 20-40 parts of solvent.

[0040] Preferably, in step S23, the drying temperature is set to 80-100° C., and the drying time is 4-8 hours.

[0041] Preferably, in step S24, the drying temperature is set to 70-80° C., and the drying time is 4-8 hours.

[0042] Preferably, the method for preparing the halogen-free flame retardant comprises the following steps:

[0043] S31, adding magnesium aluminum hydrotalcite to deionized water, adding a mixed solution of sodium hydroxide and sodium bicarbonate to adjust the pH to 9-10, adding a modifier under stirring, and reacting at 80-90° C. for 3-4 hours;

[0044] S32, after the reaction is completed, the reaction is filtered and washed three times, and the obtained solid is dried and ground to obtain a modified magnesium aluminum hydrotalcite;

[0045] S33, compounding modified magnesium aluminum hydrotalcite, octyl diphenyl phosphate and triphenyl phosphate to obtain a halogen-free flame retardant.

[0046] Preferably, the weight proportions of the components in step S31 are 5-6 parts of magnesium aluminum hydrotalcite, 100 parts of deionized water and 5-10 parts of modifier.

[0047] Preferably, the modifier in step S31 is any one of sodium stearate, silane coupling agent, sodium dodecyl sulfate and hexadecyl sulfobetaine.

[0048] Preferably, the mixed solution of sodium hydroxide and sodium bicarbonate in step S31 is prepared by adding 4.8 to 6 parts of sodium hydroxide and 2.5 to 3.5 parts of sodium bicarbonate to 100 parts of deionized water.

[0049] Preferably, in step S32, the drying temperature is set to 60-70° C., and the drying time is set to 12-24 hours.

[0050] Preferably, the weight proportions of the components in step S33 are 0.1-0.2 parts of modified magnesium aluminum hydrotalcite, 0.5-1 parts of octyl diphenyl phosphate and 0.5-1 parts of triphenyl phosphate.

[0051] Preferably, in step S10, the rotation speed of the high-speed mixer is 150-200 rpm.

[0052] Preferably, in step S20, the temperature of the feed port is 160-180°C, and the temperature of the mold port is 180-200°C.

[0053] Preferably, in step S30, the temperature of the cooling water in the water tank is 10-30° C., and the cooling time is 1-2 hours.

[0054] In summary, due to the adoption of the above technical scheme, the beneficial effects of the present invention are: through the improvement of the existing composite pipe processing technology and the compounding of the pipe components, a HDPE siphon drainage pipe with excellent antistatic, flame retardant, anti-aging, corrosion resistance and mechanical properties is prepared. Specifically, modified wood fiber reinforced particles are added to the core layer. Since polypropylene has high heat resistance and toughness, the modified wood fiber reinforced particles with polypropylene as the matrix material have good heat resistance and toughness. The modified wood fiber filler is secondary modified by phenyl hydrogen-containing siloxane and unsaturated rubber to construct a hydrophobic interface layer, so that the modified wood fiber filler in the matrix plastic has reduced agglomeration and is more tightly combined with the matrix plastic, thereby enhancing the toughness and strength of the modified wood fiber reinforced particles. The gas-phase silica can hinder the crack diffusion when the matrix material is impacted, thereby improving the impact strength of the matrix material. Maleic anhydride grafted polypropylene improves the adhesion of the modified wood fiber filler. After being used in the core layer, the blending and modification improves the heat resistance and mechanical properties of the pipe, and can enhance the adhesion of the core layer to the inner and outer layers; at the same time, a halogen-free flame retardant is added to the outer layer, and the halogen-free flame retardant is prepared by compounding modified magnesium aluminum hydrotalcite, octyl diphenyl phosphate and triphenyl phosphate. The modified magnesium aluminum hydrotalcite will release a large amount of water and carbon dioxide when it is thermally decomposed, and can absorb a large amount of heat energy to reduce the temperature of the combustion system. The pyrophosphoric acid formed by the triphenyl phosphate when heated can prevent further heat transfer, thereby slowing down the combustion rate. When the modified magnesium aluminum hydrotalcite and octyl diphenyl phosphate are thermally decomposed, a protective film will be formed on the surface of the material, which blocks the further invasion of oxygen and has a flame retardant effect. The modified magnesium aluminum hydrotalcite in the halogen-free flame retardant is not easy to agglomerate in high-density polyethylene, and the formed intercalation structure provides a channel for charge transfer, improves the conductivity of high-density polyethylene, and makes the outer layer have better antistatic ability. The formed intercalation structure improves the strength and toughness of the outer layer to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A flow chart of a method for processing a high-toughness HDPE siphon drainage pipe according to an embodiment of the present invention;

[0056] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0058] Example 1: A method for processing a high-toughness HDPE siphon drainage pipe in this example, as follows: Figure 1 As shown, steps S10-S30 are included:

[0059] S10, adding the raw materials of the inner layer, the core layer and the outer layer into a high-speed mixer respectively, the speed of the high-speed mixer is 150 rpm, and preparing mixture A, mixture B and mixture C;

[0060] S20, adding the three mixed materials into a three-layer co-extrusion die in sequence, with the feed port temperature being 180° C., the die port temperature being 200° C., and composite extrusion molding to obtain an unshaped pipe;

[0061] S30, placing the unshaped pipe into a cooling water tank with a cooling water temperature of 15° C. for cooling for 1 hour to obtain a high-toughness HDPE siphon drainage pipe.

[0062] The high-toughness HDPE siphon drainage pipe comprises an inner layer, a core layer and an outer layer which are sequentially arranged from the inside to the outside.

[0063] The inner layer is prepared from the following ingredients in parts by weight: 90 parts of high-density polyethylene, 5 parts of antistatic agent, 5 parts of thermoplastic vulcanized rubber, 2 parts of antioxidant and 3 parts of lubricant;

[0064] The core layer is prepared from the following ingredients in parts by weight: 85 parts of high-density polyethylene, 15 parts of modified wood fiber reinforcement particles, and 3 parts of lubricant;

[0065] The outer layer is prepared from the following ingredients in parts by weight: 95 parts of high-density polyethylene, 1 part of halogen-free flame retardant, 1 part of antioxidant, 3 parts of fumed silica and 3 parts of lubricant.

[0066] The high-density polyethylene is 5200B high-density polyethylene produced by Yanshan Petrochemical, the antistatic agent is hexadecyl sulfonate, the thermoplastic vulcanized rubber is a thermoplastic vulcanized rubber mixed with polypropylene and EPDM rubber in a mass ratio of 3:7, the antioxidants of the inner layer and the outer layer are both 168 antioxidants, and the lubricants of the inner layer, core layer and outer layer are all sodium stearate.

[0067] The preparation method of the modified wood fiber reinforced particles of this embodiment comprises the following steps:

[0068] S11, put 3 parts of fumed silica, 20 parts of modified wood fiber filler, 75 parts of polypropylene, 7 parts of maleic anhydride grafted polypropylene and 3 parts of sodium stearate into a high-speed mixer, set the speed to 200 rpm, stir and blend for 15 minutes to obtain feed;

[0069] S12, adding feed into a twin-rod extruder, setting the feed port temperature to 170°C, the extrusion temperature to 200°C, melt extrusion, and placing the melt into a water tank with a cooling water temperature of 15°C to cool for 40 minutes;

[0070] S13, placing the cooled melt into a pelletizer to pelletize to obtain modified wood fiber reinforced particles.

[0071] The preparation method of the modified wood fiber filler of this embodiment comprises the following steps:

[0072] S21, placing 50 parts of 30 mesh stick-shaped bamboo fibers in an oven, setting the temperature to 100° C., and drying for 12 hours for pre-drying, and spreading and flattening the fibers on a flat plate after drying;

[0073] S22, adding solvent to two reaction kettles, wherein the solvent in one reaction kettle is 15 parts, adding 0.03 parts of Custer catalyst and 0.5 parts of phenyl hydrogen siloxane at room temperature to prepare a primary modified solution, and the solvent in another reaction kettle is 30 parts, heating to 60°C, adding 3 parts of EPDM rubber to the solvent, and stirring continuously until the unsaturated rubber is completely dissolved to prepare a secondary modified solution;

[0074] S23, spraying the primary modified solution evenly on the surface of the stick-shaped bamboo fiber and continuously stirring the stick-shaped bamboo fiber, reacting at room temperature for 30 minutes, and after the reaction is completed, drying at 90° C. for 6 hours to remove the solvent, to obtain modified stick-shaped wood fiber;

[0075] S24, adding the modified rod-shaped wood fiber into the secondary modification solution, reacting for 1 minute under stirring, filtering after the reaction, and drying at 80° C. for 6 hours to obtain the modified wood fiber filler.

[0076] The preparation method of the halogen-free flame retardant of this embodiment comprises the following steps:

[0077] S31, adding 5 parts of magnesium aluminum hydrotalcite to 100 parts of deionized water, adding a mixed solution of sodium hydroxide and sodium bicarbonate to adjust the pH to 9, adding 5 parts of sodium stearate under stirring, and reacting at 80° C. for 3 hours, wherein the mixed solution of sodium hydroxide and sodium bicarbonate is 100 parts of deionized water, adding 4.8 parts of sodium hydroxide and 3.5 parts of sodium bicarbonate;

[0078] S32, after the reaction is completed, the mixture is filtered and washed three times, and the obtained solid is dried at 60° C. for 12 h and then ground to obtain a modified magnesium aluminum hydrotalcite;

[0079] S33, compounding 0.2 parts of modified magnesium aluminum hydrotalcite, 1 part of octyl diphenyl phosphate and 1 part of triphenyl phosphate to obtain a halogen-free flame retardant.

[0080] Embodiment 2, a method for processing a high-toughness HDPE siphon drainage pipe in this embodiment comprises the following steps:

[0081] S10, adding the raw materials of the inner layer, the core layer and the outer layer into a high-speed mixer respectively, the speed of the high-speed mixer is 150 rpm, and preparing mixture A, mixture B and mixture C;

[0082] S20, adding the three mixed materials into a three-layer co-extrusion die in sequence, with the feed port temperature being 160° C., the die port temperature being 180° C., and composite extrusion molding to obtain an unshaped pipe;

[0083] S30, placing the unshaped pipe into a cooling water tank with a cooling water temperature of 30° C. for cooling for 2 hours to obtain a high-toughness HDPE siphon drainage pipe.

[0084] The high-toughness HDPE siphon drainage pipe comprises an inner layer, a core layer and an outer layer which are sequentially arranged from the inside to the outside.

[0085] The inner layer is prepared from the following ingredients in parts by weight: 80 parts of high-density polyethylene, 3 parts of antistatic agent, 15 parts of thermoplastic vulcanized rubber, 2 parts of antioxidant and 3 parts of lubricant;

[0086] The core layer is prepared from the following ingredients in parts by weight: 75 parts of high-density polyethylene, 25 parts of modified wood fiber reinforcement particles, and 5 parts of lubricant;

[0087] The outer layer is prepared from the following ingredients in parts by weight: 95 parts of high-density polyethylene, 1 part of halogen-free flame retardant, 1 part of antioxidant, 3 parts of fumed silica and 3 parts of lubricant.

[0088] The high-density polyethylene is 5200B high-density polyethylene produced by Yanshan Petrochemical, the antistatic agent is monoglyceride, the thermoplastic vulcanized rubber is a thermoplastic vulcanized rubber mixed with polypropylene and ethylene propylene diene monomer rubber in a mass ratio of 3:7, the antioxidants of the inner layer and the outer layer are both 1010 antioxidants, and the lubricants of the inner layer, core layer and outer layer are all polyethylene wax.

[0089] The difference between the modified wood fiber reinforced particles and Example 1 is that the weight parts of the components are changed to 5 parts of fumed silica, 15 parts of modified wood fiber filler, 80 parts of polypropylene, 5 parts of maleic anhydride grafted polypropylene and 3 parts of polyethylene wax.

[0090] The preparation method of the modified wood fiber filler and the halogen-free flame retardant is the same as that in Example 1.

[0091] Embodiment 3, a method for processing a high-toughness HDPE siphon drainage pipe in this embodiment comprises the following steps:

[0092] S10, adding the raw materials of the inner layer, the core layer and the outer layer into a high-speed mixer respectively, the speed of the high-speed mixer is 200 rpm, and preparing mixture A, mixture B and mixture C;

[0093] S20, adding the three mixed materials into a three-layer co-extrusion die in sequence, with the feed port temperature being 160° C. and the die port temperature being 190° C., and composite extrusion molding is performed to obtain an unshaped pipe;

[0094] S30, placing the unshaped pipe into a cooling water tank with a cooling water temperature of 10° C. for cooling for 1 hour to obtain a high-toughness HDPE siphon drainage pipe.

[0095] The high-toughness HDPE siphon drainage pipe comprises an inner layer, a core layer and an outer layer which are sequentially arranged from the inside to the outside.

[0096] The inner layer is prepared from the following ingredients in parts by weight: 94 parts of high-density polyethylene, 1 part of antistatic agent, 5 parts of thermoplastic vulcanized rubber, 1 part of antioxidant and 5 parts of lubricant;

[0097] The core layer is prepared from the following ingredients in parts by weight: 85 parts of high-density polyethylene, 15 parts of modified wood fiber reinforcement particles, and 5 parts of lubricant;

[0098] The outer layer is prepared from the following ingredients in parts by weight: 91 parts of high-density polyethylene, 2 parts of halogen-free flame retardant, 2 parts of antioxidant, 5 parts of fumed silica and 5 parts of lubricant.

[0099] The high-density polyethylene is 5200B high-density polyethylene produced by Yanshan Petrochemical, the antistatic agent is HIPS antistatic agent, the thermoplastic vulcanized rubber is a thermoplastic vulcanized rubber mixed with polypropylene and EPDM rubber in a mass ratio of 3:7, the antioxidants of the inner layer and the outer layer are both 1098 antioxidants, and the lubricants of the inner layer, core layer and outer layer are all zinc stearate.

[0100] The preparation method of the modified wood fiber reinforced particles and the halogen-free flame retardant is the same as that in Example 1.

[0101] The difference between the modified wood fiber filler and Example 1 is that the rod-shaped wood fiber raw material is changed to 40-mesh rod-shaped straw fiber.

[0102] Embodiment 4, a method for processing a high-toughness HDPE siphon drainage pipe in this embodiment comprises the following steps:

[0103] S10, adding the raw materials of the inner layer, the core layer and the outer layer into a high-speed mixer respectively, the speed of the high-speed mixer is 200 rpm, and preparing mixture A, mixture B and mixture C;

[0104] S20, adding the three mixed materials into a three-layer co-extrusion die in sequence, with the feed port temperature being 180° C., the die port temperature being 200° C., and composite extrusion molding to obtain an unshaped pipe;

[0105] S30, placing the unshaped pipe into a cooling water tank with a cooling water temperature of 30° C. for cooling for 2 hours to obtain a high-toughness HDPE siphon drainage pipe.

[0106] The high-toughness HDPE siphon drainage pipe comprises an inner layer, a core layer and an outer layer which are sequentially arranged from the inside to the outside.

[0107] The inner layer is prepared from the following ingredients in parts by weight: 80 parts of high-density polyethylene, 3 parts of antistatic agent, 15 parts of thermoplastic vulcanized rubber, 2 parts of antioxidant and 3 parts of lubricant;

[0108] The core layer is prepared from the following ingredients in parts by weight: 80 parts of high-density polyethylene, 20 parts of modified wood fiber reinforcement particles, and 5 parts of lubricant;

[0109] The outer layer is prepared from the following ingredients in parts by weight: 96 parts of high-density polyethylene, 1 part of halogen-free flame retardant, 1 part of antioxidant, 2 parts of fumed silica and 3 parts of lubricant.

[0110] The high-density polyethylene is 5200B high-density polyethylene produced by Yanshan Petrochemical, the antistatic agent is hexadecyl sulfonate, the thermoplastic vulcanized rubber is a thermoplastic vulcanized rubber mixed with polypropylene and ethylene propylene diene monomer rubber in a mass ratio of 3:7, the antioxidants of the inner layer and the outer layer are both 1010 antioxidants, and the lubricants of the inner layer, core layer and outer layer are all polyethylene wax.

[0111] The preparation method of the modified wood fiber reinforced particles and the modified wood fiber filler is the same as that in Example 1.

[0112] The difference between the halogen-free flame retardant and Example 1 is that the modifier component is sodium dodecyl sulfate.

[0113] Comparative Example 1: The difference between this comparative example and Example 1 is that the modified wood fiber filler is not added to the modified wood fiber reinforced particles.

[0114] Comparative Example 2: This comparative example differs from Example 1 in that the amount of the modified wood fiber reinforced particles is changed to 5 parts of fumed silica, 60 parts of modified wood fiber filler, 40 parts of polypropylene, 10 parts of maleic anhydride grafted polypropylene and 5 parts of lubricant.

[0115] Comparative Example 3: This comparative example differs from Example 1 in that no fumed silica is added to the ingredients of the modified wood fiber reinforced particles.

[0116] Comparative Example 4: This comparative example differs from Example 1 in that the modified magnesium aluminum hydrotalcite is not added to the halogen-free flame retardant.

[0117] Test Example 1: The high-toughness HDPE siphon drainage pipe prepared in each embodiment and comparative example was tested for performance data using commercially available testing equipment. The test results are shown in Table 1 below:

[0118] Table 1

[0119]

[0120]

[0121] Test Example 2: The prepared HDPE siphon drainage pipe was immersed in 3.5wt% dilute hydrochloric acid for 72h, and the tensile yield strength and nominal strain at break after immersion were tested. The test results are shown in Table 2 below:

[0122] Table 2

[0123]

[0124] From the data in Table 1, it can be seen that the surface resistance of the HDPE siphon drainage pipes prepared in each embodiment is 4.9×10 6 ~5.1×10 6 Ω, indicating that the HDPE siphon drainage pipes prepared in each embodiment have excellent antistatic ability; the limiting oxygen index is between 37.5 and 39.3%, indicating that the HDPE siphon drainage pipes prepared in each embodiment have excellent flame retardant ability; the tensile yield strength is above 35MPa, and the nominal strain at break is above 370%, indicating that the HDPE siphon drainage pipes prepared in each embodiment have excellent strength and toughness; the simply supported beam impact strength is greater than 25KJ / m 2 , indicating that the HDPE siphon drainage pipes prepared in each embodiment have excellent impact resistance. From the data in Table 2, it can be seen that after being immersed in 3.5wt% dilute hydrochloric acid for 72 hours, the tensile yield strength of the HDPE siphon drainage pipes prepared in each embodiment is between 29.6 and 30.1MPa, and the nominal strain at break is between 311 and 316%, indicating that the HDPE siphon drainage pipes prepared in each embodiment have excellent corrosion resistance and aging resistance, and further indicating that the HDPE siphon drainage pipes prepared by the processing method of the present invention have excellent antistatic, flame retardant, anti-aging, corrosion resistance and mechanical properties.

[0125] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0126] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for processing high-toughness HDPE siphon drainage pipe, characterized in that: The steps include: S10, adding the raw materials of the inner layer, the core layer and the outer layer into a high-speed mixer respectively to obtain a mixture A, a mixture B and a mixture C; S20, adding the three mixed materials into a three-layer co-extrusion die in sequence, and composite extruding and molding to obtain an unshaped pipe; S30, placing the unshaped pipe into a cooling water tank for cooling to obtain a high-toughness HDPE siphon drainage pipe; The inner layer is prepared from the following components in parts by weight: 80-94 parts of high-density polyethylene, 1-5 parts of antistatic agent, 5-15 parts of thermoplastic vulcanized rubber, 0.5-2 parts of antioxidant and 1-5 parts of lubricant; The core layer is prepared from the following components in parts by weight: 75-90 parts of high-density polyethylene, 10-25 parts of modified wood fiber reinforcement particles and 1-5 parts of lubricant; The outer layer is prepared from the following components in parts by weight: 91-98.5 parts of high-density polyethylene, 0.5-2 parts of halogen-free flame retardant, 0.5-2 parts of antioxidant, 0.5-5 parts of fumed silica and 1-5 parts of lubricant.

2. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 1, characterized in that: The antistatic agent is any one of hexadecyl sulfonate, monoglyceride and HIPS antistatic agent, the thermoplastic vulcanized rubber is a thermoplastic vulcanized rubber composed of polypropylene / ethylene propylene diene monomer rubber, the antioxidants of the inner layer and the outer layer are one or more combinations of 168, 1010, 1098 and 1076, and the lubricants of the inner layer, core layer and outer layer are one or more combinations of sodium stearate, zinc stearate and polyethylene wax.

3. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 1, characterized in that: The method for preparing the modified wood fiber reinforced particles comprises the following steps: S11, putting fumed silica, modified wood fiber filler, polypropylene, maleic anhydride grafted polypropylene and lubricant into a high-speed mixer and stirring and blending for 10 to 15 minutes to obtain feed; S12, adding the feed material into the twin-rod extruder for melt extrusion, and placing the melt into a water tank for cooling for 30 to 60 minutes; S13, placing the cooled melt into a pelletizer to pelletize to obtain modified wood fiber reinforced particles.

4. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 3, characterized in that: The preparation method of the modified wood fiber filler comprises the following steps: S21, placing the stick-shaped wood fibers in an oven for pre-drying, and spreading them on a flat plate after drying; S22, adding a solvent into two reaction kettles, adding a catalyst and phenyl hydrogen siloxane into one of the reaction kettles at room temperature to obtain a primary modified solution, and heating the other reaction kettle to 50-60° C., adding an unsaturated rubber into the solvent, and continuously stirring until the unsaturated rubber is completely dissolved to obtain a secondary modified solution; S23, spraying the primary modified solution evenly on the surface of the rod-shaped wood fiber and continuously stirring the rod-shaped wood fiber, reacting at room temperature for 20 to 40 minutes, and after the reaction is completed, drying to remove the solvent to obtain modified rod-shaped wood fiber; S24, adding the modified rod-shaped wood fiber into the secondary modification solution, reacting for 1 to 3 minutes under stirring, and filtering and drying after the reaction to obtain the modified wood fiber filler.

5. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 3, characterized in that: In step S11, the lubricant is any one of sodium stearate, zinc stearate and polyethylene wax, and the weight parts of each component are 1-5 parts of fumed silica, 15-30 parts of modified wood fiber filler, 70-85 parts of polypropylene, 5-10 parts of maleic anhydride grafted polypropylene and 1-5 parts of lubricant. The speed of the high-speed mixer is 150-200rpm. In step S12, the feed port temperature of the twin-rod extruder is 160-180°C, the extrusion temperature is 190-210°C, and the cooling water temperature in the water tank is 10-30°C.

6. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 4, characterized in that: In step S21, the rod-shaped wood fiber is any one of bamboo fiber, straw fiber and rice husk fiber, the specification is 30-40 mesh, the weight of wood powder is 50 parts, the oven temperature for pre-drying treatment is set to 100-105° C., the drying time is 12-18 hours, the catalyst in step S22 is a platinum-containing catalyst, the phenyl hydrogen-containing siloxane is a hydrogen-containing siloxane with a low phenyl content, the solvent is any one of n-hexane, toluene, n-heptane and n-propanol, and the unsaturated rubber is nitrile rubber, EPDM rubber Any one of rubber and isoprene rubber, the weight parts of each substance in preparing the primary modified solution are 0.01-0.05 parts of catalyst, 0.5-1 parts of phenyl hydrogen siloxane and 10-20 parts of solvent, the weight parts of each substance in preparing the secondary modified solution are 1-3 parts of unsaturated rubber and 20-40 parts of solvent, the drying temperature in step S23 is set to 80-100°C, the drying time is 4-8h, and the drying temperature in step S24 is set to 70-80°C, and the drying time is 4-8h.

7. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 1, characterized in that: The preparation method of the halogen-free flame retardant comprises the following steps: S31, adding magnesium aluminum hydrotalcite to deionized water, adding a mixed solution of sodium hydroxide and sodium bicarbonate to adjust the pH to 9-10, adding a modifier under stirring, and reacting at 80-90° C. for 3-4 hours; S32, after the reaction is completed, the reaction is filtered and washed three times, and the obtained solid is dried and ground to obtain a modified magnesium aluminum hydrotalcite; S33, compounding modified magnesium aluminum hydrotalcite, octyl diphenyl phosphate and triphenyl phosphate to obtain a halogen-free flame retardant.

8. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 7, characterized in that: In step S31, the weight parts of each component are 5-6 parts of magnesium aluminum hydrotalcite, 100 parts of deionized water and 5-10 parts of modifier, the modifier is any one of sodium stearate, silane coupling agent, sodium dodecyl sulfate and hexadecyl sulfobetaine, the mixed solution of sodium hydroxide and sodium bicarbonate is 100 parts of deionized water with 4.8-6 parts of sodium hydroxide and 2.5-3.5 parts of sodium bicarbonate added, the drying temperature in step S32 is set to 60-70°C, and the drying time is 12-24h, and the weight parts of each component in step S33 are 0.1-0.2 parts of modified magnesium aluminum hydrotalcite, 0.5-1 parts of octyl diphenyl phosphate and 0.5-1 parts of triphenyl phosphate.

9. The method for processing a high-toughness HDPE siphon drainage pipe according to claim 1, characterized in that: In step S10, the speed of the high-speed mixer is 150-200 rpm, in step S20, the temperature of the feed port is 160-180° C., the temperature of the mold port is 180-200° C., in step S30, the temperature of the cooling water in the water tank is 10-30° C., and the cooling time is 1-2 hours.

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