A hard polyvinyl chloride pipe with corrosion resistance and good resilience and a preparation method thereof

Abstract

The application relates to the field of polyvinyl chloride, and particularly discloses a hard polyvinyl chloride pipe with good corrosion resistance and good resilience and a preparation method thereof. The hard polyvinyl chloride pipe with good corrosion resistance and good resilience comprises the following components: 100 parts of modified polyvinyl chloride resin, 7-8 parts of calcium carbonate, 4.5-5 parts of chlorinated polyethylene, 1.3-1.5 parts of calcium stearate, 3.2-3.5 parts of a stabilizer, 2-2.5 parts of ACR resin, 0.85-0.9 parts of polyethylene wax and 1-1.2 parts of stearic acid. The hard polyvinyl chloride pipe has good resilience and corrosion resistance.

Description

Technical Field

[0001] This application relates to the field of polyvinyl chloride, and more specifically, to a corrosion-resistant and highly resilient rigid polyvinyl chloride pipe and a method for preparing the same. Background Technology

[0002] Rigid PVC pipes, with their excellent mechanical properties, corrosion resistance, and cost-effectiveness, are widely used in water supply and drainage, chemical transportation, and agricultural irrigation. However, with the increasing prevalence of complex corrosive environments, the shortcomings of existing PVC pipes are becoming increasingly apparent, making them unsuitable for high-end service requirements. Traditional rigid PVC pipes are extruded using resin, stabilizers, lubricants, and other additives, but they suffer from two major drawbacks during use: first, under long-term exposure to corrosive media such as acids, alkalis, and salts, the resin molecular chains are easily degraded, and the additives are easily worn away, resulting in mechanical degradation and a shortened service life; second, PVC is brittle, and the pipes have poor resilience after being subjected to external pressure or low-temperature impact, making them prone to permanent deformation and cracking, a problem particularly pronounced in large-diameter pipes. Current industry modification solutions simply increase the amount of stabilizer, leading to worsened processing fluidity, and the addition of impact modifiers reduces the pipe's corrosion resistance and is costly, failing to simultaneously achieve corrosion resistance, high resilience, and ease of processing.

[0003] Therefore, there is an urgent need to provide a rigid polyvinyl chloride pipe with easy processing, corrosion resistance and excellent resilience. Summary of the Invention

[0004] In order to improve the corrosion resistance and resilience of rigid polyvinyl chloride (PVC) pipes, this application provides a corrosion-resistant and resilient rigid PVC pipe and a method for preparing the same.

[0005] Firstly, this application provides a corrosion-resistant and highly resilient rigid polyvinyl chloride pipe, which adopts the following technical solution: A corrosion-resistant and resilient rigid polyvinyl chloride pipe comprises the following raw materials in parts by weight: 100 parts modified polyvinyl chloride resin, 7-8 parts calcium carbonate, 4.5-5 parts chlorinated polyethylene, 1.3-1.5 parts calcium stearate, 3.2-3.5 parts stabilizer, 2-2.5 parts ACR resin, 0.85-0.9 parts polyethylene wax, and 1-1.2 parts stearic acid.

[0006] By adopting the above technical solutions, polyvinyl chloride resin powder, as the matrix resin, provides the basic mechanical properties and chemical corrosion resistance of the pipe; calcium carbonate, as a filler modifier, improves the rigidity, dimensional stability, and heat resistance of the pipe; chlorinated polyethylene can construct a network-like structure in the polyvinyl chloride resin matrix, inducing the matrix to undergo large-scale shear yielding and other plastic deformations, thereby efficiently absorbing and dissipating impact energy and improving toughness; ACR resin promotes uniform plasticization, improves melt strength, and enhances the surface finish of the pipe; calcium stearate assists in stabilization, improves material flowability and demolding properties, and delays the aging process. The stabilizer inhibits the thermal degradation of PVC molecular chains and absorbs corrosive substances produced by degradation. The two work synergistically to effectively improve the pipe's resistance to chemical corrosion and weathering. In addition, polyethylene wax, as an external lubricant, reduces friction between the melt and the metal surface of the equipment, improves extrusion efficiency, optimizes plasticizing rate, and improves processing fluidity. Stearic acid, as an internal lubricant, promotes lubrication between resin particles and improves plasticizing uniformity. The internal lubricant optimizes the uniformity of resin plasticizing, while the external lubricant reduces frictional adhesion to the equipment. The combined use of the two effectively improves production efficiency and the surface forming quality of the pipe.

[0007] Optionally, the stabilizer is a calcium-zinc stabilizer.

[0008] Optionally, the preparation method of the modified polyvinyl chloride resin includes the following steps: Polyvinyl chloride resin was added to tetrahydrofuran and stirred to dissolve. The temperature was raised to 65-70℃, and under an inert gas atmosphere, polymethylhydrosiloxane, hexafluorobutyl acrylate, phosphate acrylate flame retardant monomer and azobisisobutyronitrile were added in sequence. The mixture was stirred evenly and reacted at 60-75℃ for 4-6 hours. The temperature was raised to 80-85℃ and held for 5 minutes. The mixture was cooled to the standard ambient temperature, and the precipitate was formed. The precipitate was filtered and washed to obtain modified polyvinyl chloride resin.

[0009] Optionally, the mass ratio of the polymethylhydrosiloxane, hexafluorobutyl acrylate, phosphate acrylate flame retardant monomer and azobisisobutyronitrile is 5-8:4-6:5-6:1.2-1.5.

[0010] By employing the above technical solution, after the fluorinated acrylic acid grafted segments are grafted and copolymerized into the polyvinyl chloride (PVC) molecular chain, their low surface energy fluorinated side chains form a dense protective layer on the material surface, acting as a chemically inert barrier in the system. The organosilicon grafted segments possess a compliant Si-O-Si main chain structure with a low glass transition temperature and excellent molecular chain mobility. Through chemical bonding and grafting onto the PVC main chain, they reduce the material modulus and impart flexibility and elastic deformation capabilities to the matrix. Simultaneously, the fluorinated acrylic acid grafted segments further exert a targeted protective effect on the material surface, reducing surface energy and hindering the penetration of corrosive media, thus promoting the material's resistance to chemical corrosion and solvent absorption. Significantly improved expansion performance; the organosilicon grafted segments further endow the molecular chains with high flexibility and deformation recovery ability through the characteristics of long Si-O bond length, large bond angle and low internal rotation barrier within the polyvinyl chloride matrix, playing an elastic enhancement role in deformation energy storage and elastic recovery under external force, promoting the synergistic enhancement of material compression set reduction and springback rate; in addition, the surface enrichment of fluorinated segments and the internal elasticization of organosilicon segments produce a synergistic effect, the surface fluorine layer blocks the invasion of corrosive media to protect the integrity of the matrix, and the internal silicon segments provide flexible buffer to dissipate stress and maintain reversible recovery after deformation. The two work together to improve the corrosion resistance and resilience of polyvinyl chloride matrix.

[0011] Optionally, the corrosion-resistant and resilient rigid polyvinyl chloride pipe further includes functional additives, and the preparation method of the functional additives includes the following steps: Under an inert gas atmosphere, hexafluoropropylene oxide trimer alcohol methacrylate, phosphorus-containing acrylate monomers, and hydroxyethyl acrylate were added to butyl acetate and stirred until homogeneous. The mixture was then heated to 65-70 °C, and a dilute solution of butyl acetate containing azobisisobutyronitrile was added dropwise. The mixture was polymerized at a constant temperature for 4-5 hours, then heated to 75 °C and held for 1.5 hours. The mixture was then subjected to reduced pressure treatment at 80 °C and a vacuum of -0.08 to -0.09 MPa. After pulverization and sieving, the functional additive was obtained.

[0012] Optionally, the mass ratio of the hexafluoropropylene oxide trimer alcohol methacrylate, the phosphorus-containing acrylate monomer, and the hydroxyethyl acrylate is 100:8-10:7-8.

[0013] Optionally, the mass ratio of the modified polyvinyl chloride resin to the functional additive is 100:6-9.

[0014] By employing the above technical solution, organosilicon flexible side chains, fluorinated low surface energy side chains, and organophosphorus stabilizing groups are introduced into the main molecular chain of polyvinyl chloride resin through solution grafting, resulting in a prefunctionalized polyvinyl chloride body at the molecular level, which acts as the basic framework for flexibility, resilience, and surface protection in the system. The functional additives possess multiple functional structures, including fluorinated polyether low surface energy segments, phosphorus-containing anti-corrosion active groups, and vinyl chloride affinity and compatibility segments. These additives are prepared through high-temperature melting and migrate to the interface between polyvinyl chloride and ACR phases during blending, thereby constructing interfacial bonding bridges, reducing interfacial tension, and promoting effective stress transfer. Based on this, functional... The additives further act as a flexible buffer layer at the interface between PVC and ACR resin, improving the dispersion of ACR core-shell particles in PVC, optimizing the interfacial compatibility between ACR and PVC, and fully leveraging the role of the ACR core-shell structure in impact energy dissipation, thereby improving the deformation recovery ability of PVC molecular chains after unloading external forces. Chlorinated polyethylene elastomer further plays a targeted elasticity enhancement role in stress dissipation and deformation energy storage within PVC through flexible molecular chains with low glass transition temperatures, promoting rapid recovery of material deformation and significant reduction in compression set after unloading external forces.

[0015] Meanwhile, during high-temperature melt blending and molding, the grafted fluorinated side chains and the fluorinated polyether segments in the functional additives generate an affinity enrichment effect between fluorine and fluorine molecular chains on the material surface, forming a double-layered, dense, low surface energy protective layer. This effectively blocks the penetration path of corrosive media and significantly improves the chemical corrosion resistance of the matrix. The grafted organosilicon segments and the flexible molecular chains of chlorinated polyethylene form a synergistic elasticity structure, further promoting the effective utilization of the matrix's deformation recovery ability. The grafted organophosphorus groups and the phosphorus-containing segments in the functional additives work synergistically to promote the cross-linking of polyvinyl chloride into carbon to form a dense carbon layer, while also playing a role in capturing gas-phase free radicals. This condensed-phase-gas-phase synergistic flame retardant mechanism, combined with the metal ion complexation passivation effect, significantly enhances the long-term stability of the material under thermo-oxidative aging and corrosive environments.

[0016] Secondly, this application provides a corrosion-resistant and highly resilient rigid polyvinyl chloride pipe and its preparation method, employing the following technical solution: A method for preparing a corrosion-resistant and highly resilient rigid polyvinyl chloride pipe includes the following steps: (1) The modified polyvinyl chloride resin, calcium carbonate, calcium stearate, chlorinated polyethylene, calcium zinc stabilizer and ACR resin are stirred at high speed and heated to 80-90°C. Polyethylene wax and stearic acid are added and the temperature is further increased to 110-120°C. The material is then transferred to a cold mixer and cooled to below 40°C to obtain a dry mixture. (2) The dry mixture is melted and plasticized at 160-190℃, extruded and sized under vacuum, cooled by spraying, cut, and inspected to obtain a corrosion-resistant and resilient rigid polyvinyl chloride pipe.

[0017] By adopting the above technical solution, the material extrusion has good fluidity, it is easy to achieve uniform mixing of raw materials, and the operation is simple and easy to process, which can be used for continuous production.

[0018] In summary, this application has the following beneficial effects: 1. This application preferably uses polyvinyl chloride as the base resin to provide mechanical support and corrosion resistance; calcium carbonate enhances rigidity, dimensional stability and heat resistance; chlorinated polyethylene improves toughness; ACR resin improves melt strength and surface finish; calcium stearate improves flowability and mold release; stabilizers inhibit thermal degradation and absorb corrosive substances, and the two work together to enhance chemical corrosion resistance and weather resistance; polyethylene wax and stearic acid form an internal and external lubrication system to ensure processing stability.

[0019] 2. In this application, fluorinated acrylic acid grafted segments are embedded into the polyvinyl chloride (PVC) molecular chain via graft copolymerization, acting as a chemical inert barrier in the system. Organosilicon grafted segments are chemically bonded to the PVC main chain, achieving a reduction in material modulus and imparting flexibility and elastic deformation capability to the matrix. The fluorinated acrylic acid grafted segments significantly improve the material's resistance to chemical corrosion and swelling under various media. The organosilicon grafted segments further endow the PVC matrix with high flexibility and deformation recovery capability, playing a role in storing deformation energy and enhancing elasticity under external forces, thus promoting a synergistic enhancement of reduced compression set and increased resilience. Furthermore, the surface enrichment of fluorinated segments and the internal elasticity enhancement of organosilicon segments create a synergistic effect. The surface fluorine layer blocks the intrusion of corrosive media to protect the integrity of the matrix, while the internal silicon segments provide flexible buffering to dissipate stress and maintain reversible recovery after deformation. These two elements work synergistically to improve the corrosion resistance and resilience of the PVC matrix.

[0020] 3. This application employs functional additives containing low surface energy segments of fluorinated polyethers, phosphorus-containing anti-corrosion active groups, and vinyl chloride affinity and compatibility segments. These additives can be prepared by high-temperature melting and migrate to the interface between polyvinyl chloride (PVC) and ACR resin during the blending process, thereby constructing interfacial bonding bridges, reducing interfacial tension, and promoting effective stress transfer. The functional additives further act as a flexible buffer layer at the interface between PVC and ACR resin, optimizing the interfacial compatibility between ACR and PVC elastomer, and improving the deformation recovery ability of PVC molecular chains after unloading external forces. The chlorinated polyethylene elastomer, through its flexible molecular chains, plays a targeted elasticity enhancement role by dissipating stress and storing deformation energy, promoting rapid recovery of material deformation and a significant reduction in permanent compression set after unloading external forces. Detailed Implementation

[0021] The following embodiments provide a further detailed description of this application.

[0022] Preparation examples of functional additives The phosphorus-containing acrylate monomer is designated as SIPOMER PAM-100.

[0023] Preparation Example 1 Under a nitrogen atmosphere, 100g of hexafluoropropylene oxide trimer alcohol methacrylate, 10g of phosphorus-containing acrylate monomer and 8g of hydroxyethyl acrylate were added to 150g of butyl acetate and stirred until homogeneous. The mixture was heated to 70℃, and 150g of a dilute butyl acetate solution containing 3g of azobisisobutyronitrile was added dropwise. The mixture was polymerized at a constant temperature for 5h, then heated to 75℃ and held for 1.5h. The mixture was then subjected to reduced pressure treatment at 80℃ and -0.09 MPa vacuum, pulverized and sieved to obtain the functional additive.

[0024] Preparation Example 2 Under a nitrogen atmosphere, 100g of hexafluoropropylene oxide trimer alcohol methacrylate, 8g of phosphorus-containing acrylate monomer and 7g of hydroxyethyl acrylate were added to 150g of butyl acetate and stirred evenly. The mixture was heated to 65℃, and 150g of a dilute butyl acetate solution containing 3g of azobisisobutyronitrile was added dropwise. The mixture was polymerized at a constant temperature for 4h, then heated to 75℃ and held for 1.5h. The mixture was then subjected to reduced pressure treatment at 80℃ and -0.08MPa vacuum, pulverized and sieved to obtain the functional additive.

[0025] Preparation example of modified polyvinyl chloride resin The polyvinyl chloride resin was purchased from Shanxi Yushe Chemical Co., Ltd., and its model number is SG-5.

[0026] Preparation Example 1 100g of polyvinyl chloride resin was added to 500g of tetrahydrofuran and stirred to dissolve. The mixture was heated to 70℃ and, under a nitrogen atmosphere, 8g of polymethylhydrosiloxane, 6g of hexafluorobutyl acrylate, 6g of phosphate acrylate flame retardant monomer, and 1.5g of azobisisobutyronitrile were added sequentially. The mixture was mixed evenly and reacted at 75℃ for 4h. The temperature was then raised to 85℃ and held for 5min. The mixture was cooled to the standard ambient temperature, and a precipitate was formed. The precipitate was filtered, washed, and the modified polyvinyl chloride resin was obtained.

[0027] Preparation Example 2 100g of polyvinyl chloride resin was added to 500g of tetrahydrofuran and stirred to dissolve. The mixture was heated to 65℃ and, under a nitrogen atmosphere, 5g of polymethylhydrosiloxane, 4g of hexafluorobutyl acrylate, 5g of phosphate acrylate flame retardant monomer, and 1.2g of azobisisobutyronitrile were added sequentially. The mixture was mixed evenly and reacted at 60℃ for 6h. The temperature was then raised to 80℃ and held for 5min. The mixture was cooled to the standard ambient temperature, and a precipitate was formed. The precipitate was filtered, washed, and the modified polyvinyl chloride resin was obtained.

[0028] Preparation Example 3 Compared to Preparation Example 1, no polymethylhydrosiloxane was added.

[0029] Preparation Example 4 Compared to Preparation Example 1, no hexafluorobutyl acrylate was added.

[0030] Example

[0031] In the following examples, polyethylene wax was purchased from Yanshan Jilian Petrochemical, model SX-100B; calcium carbonate was purchased from Jiangxi Chengmou Biotechnology Co., Ltd., model CM-2618; chlorinated polyethylene was purchased from Shandong Haoxiang Chemical Co., Ltd., model 135A; stearic acid was purchased from Shandong Gaomi Youqiang Additives Co., Ltd., model SA1801; calcium stearate was purchased from Jiangxi Hongyuan Chemical Co., Ltd., model 2018X; ACR resin was purchased from Shandong Ruifeng Polymer Materials Co., Ltd., model IP401; and calcium-zinc stabilizer was purchased from Hebei Tianyu Chemical Co., Ltd., model TY-Q302.

[0032] Example 1: A rigid polyvinyl chloride (PVC) pipe with corrosion resistance and good resilience. The raw material amounts are shown in Table 1. A method for preparing a rigid PVC pipe with corrosion resistance and good resilience is described, wherein the modified PVC resin is prepared using the method described in Example 1, and includes the following steps: (1) Modified polyvinyl chloride resin, calcium carbonate, calcium stearate, chlorinated polyethylene, calcium zinc stabilizer and ACR resin are added to a high-speed mixer, stirred at high speed and heated to 90°C, polyethylene wax and stearic acid are added, and the temperature is further increased to 120°C. The material is then transferred to a cold mixer and cooled to 38°C to obtain a dry mixture. (2) Add the dry mixture to the twin-screw extruder, melt and plasticize at 190°C, extrude and shape, vacuum sizing, spray cooling, cut, and inspect to obtain a corrosion-resistant and resilient rigid polyvinyl chloride pipe.

[0033] Table 1. Raw material consumption of rigid polyvinyl chloride pipes in Examples 1-3 and Comparative Examples 1 and 2.

[0034] Example 2: A corrosion-resistant and highly resilient rigid polyvinyl chloride (PVC) pipe, differing from Example 1 in that the raw material amounts are shown in Table 1. The method for preparing the corrosion-resistant and highly resilient rigid PVC pipe involves using the modified PVC resin prepared in Example 2, and includes the following steps: (1) Modified polyvinyl chloride resin, calcium carbonate, calcium stearate, chlorinated polyethylene, calcium zinc stabilizer and ACR resin are added to a high-speed mixer, stirred at high speed and heated to 85°C, polyethylene wax and stearic acid are added, and the temperature is further increased to 115°C. The material is then transferred to a cold mixer and cooled to 38°C to obtain a dry mixture. (2) Add the dry mixture to a twin-screw extruder, melt and plasticize at 180°C, extrude and shape, vacuum sizing, spray cooling, cut, and inspect to obtain a corrosion-resistant and resilient rigid polyvinyl chloride pipe.

[0035] Example 3: A corrosion-resistant and highly resilient rigid polyvinyl chloride (PVC) pipe, differing from Example 1 in that the raw material amounts are as shown in Table 1, and the modified PVC resin is prepared using the method described in Example 1. The preparation method of the corrosion-resistant and highly resilient rigid PVC pipe includes the following steps: (1) Modified polyvinyl chloride resin, calcium carbonate, calcium stearate, chlorinated polyethylene, calcium zinc stabilizer and ACR resin are added to a high-speed mixer, stirred at high speed and heated to 80°C, polyethylene wax and stearic acid are added, and the temperature is further increased to 110°C. The material is then transferred to a cold mixer and cooled to 38°C to obtain a dry mixture. (2) Add the dry mixture to the twin-screw extruder, melt and plasticize at 160°C, extrude and shape, vacuum sizing, spray cooling, cut, and inspect to obtain a corrosion-resistant and resilient rigid polyvinyl chloride pipe.

[0036] Example 4: A corrosion-resistant and resilient rigid polyvinyl chloride pipe, which differs from Example 1 in that the modified polyvinyl chloride resin is prepared using the method in Example 3 of modified polyvinyl chloride resin preparation.

[0037] Example 5: A corrosion-resistant and resilient rigid polyvinyl chloride pipe, which differs from Example 1 in that the modified polyvinyl chloride resin is prepared using the method in Example 4 of modified polyvinyl chloride resin preparation.

[0038] Comparative Example Comparative Example 1: A corrosion-resistant and highly resilient rigid polyvinyl chloride (PVC) pipe, differing from Example 1 in that the raw material amounts are as shown in Table 1, and the functional additives are prepared using the method described in Functional Additive Preparation Example 1. The preparation method of the corrosion-resistant and highly resilient rigid PVC pipe includes the following steps: (1) Modified polyvinyl chloride resin, calcium carbonate, calcium stearate, chlorinated polyethylene, calcium zinc stabilizer, ACR resin and functional additives are added to a high-speed mixer, stirred at high speed and heated to 90°C, polyethylene wax and stearic acid are added, and the temperature is further increased to 120°C. The material is then transferred to a cold mixer and cooled to 38°C to obtain a dry mixture. (2) Add the dry mixture to the twin-screw extruder, melt and plasticize at 190°C, extrude and shape, vacuum sizing, spray cooling, cut, and inspect to obtain a corrosion-resistant and resilient rigid polyvinyl chloride pipe.

[0039] Comparative Example 2: A corrosion-resistant and highly resilient rigid polyvinyl chloride (PVC) pipe, differing from Example 1 in that the raw material amounts are as shown in Table 1, and the functional additives are prepared using the method described in Functional Additive Preparation Example 2. The preparation method of the corrosion-resistant and highly resilient rigid PVC pipe includes the following steps: (1) Modified polyvinyl chloride resin, calcium carbonate, calcium stearate, chlorinated polyethylene, calcium zinc stabilizer, ACR resin and functional additives are added to a high-speed mixer, stirred at high speed and heated to 90°C, polyethylene wax and stearic acid are added, and the temperature is further increased to 120°C. The material is then transferred to a cold mixer and cooled to 38°C to obtain a dry mixture. (2) Add the dry mixture to the twin-screw extruder, melt and plasticize at 190°C, extrude and shape, vacuum sizing, spray cooling, cut, and inspect to obtain a corrosion-resistant and resilient rigid polyvinyl chloride pipe.

[0040] Comparative Example 3: A rigid polyvinyl chloride pipe with good corrosion resistance and resilience, which differs from Example 1 in that the modified polyvinyl chloride resin is replaced by an equal amount of polyvinyl chloride resin.

[0041] Performance testing

[0042] Corrosion-resistant and resilient rigid polyvinyl chloride pipes were prepared according to the methods in the examples and comparative examples, and their performance was tested according to the following methods. The test results are recorded in Table 2.

[0043] 1. Longitudinal shrinkage rate: The longitudinal shrinkage rate is tested in accordance with GB / T 6671-2001 "Determination of longitudinal shrinkage rate of thermoplastic pipes".

[0044] 2. Drop hammer impact test: The drop hammer impact test is conducted in accordance with GB / T 14152-2001 "Test method for resistance to external impact of thermoplastic pipes - clockwise rotation method", and the test temperature is 0℃.

[0045] 3. Corrosion Resistance Durability Test: 50wt% NaCl solution, 10wt% sulfuric acid solution, and 40wt% sodium hydroxide solution were prepared as corrosion media. Samples prepared in the examples and comparative examples were immersed in the corrosion media for corrosion treatment. After standing in a 60℃ constant temperature oven for 200 hours, the samples were rinsed with water and dried with hot air. The mass and tensile properties of the samples before and after corrosion treatment were tested. Tensile properties were tested using a universal testing machine, referring to the relevant provisions of GB / T 1040-2022 "Determination of Tensile Properties of Plastics". The test temperature was 25℃, and the tensile rate was 50 mm / min. The degree of corrosion of the sample in the medium was characterized by the tensile strength loss rate of each group of samples. Tensile strength loss rate = (initial tensile strength - tensile strength after corrosion) / initial tensile strength × 100%; Mass loss rate = (initial sample mass - sample mass after corrosion) / initial sample mass × 100%.

[0046] Table 2. Performance test results of rigid polyvinyl chloride pipes prepared in the examples and comparative examples.

[0047] As shown in Table 2, the rigid PVC pipes prepared in Examples 1-3 of this application have good resilience and corrosion resistance. Comparing Example 4 with Example 1, it can be seen that the preparation of the modified PVC resin without the addition of polymethylhydrosiloxane resulted in a slight decrease in resilience, which may be due to the lack of polymethylhydrosiloxane leading to reduced elastic deformation. Comparing Example 5 with Example 1, it can be seen that the preparation of the modified PVC resin without the addition of hexafluorobutyl acrylate resulted in a slight decrease in corrosivity, which may be due to the lack of hexafluorobutyl acrylate leading to reduced chemical corrosion resistance and resistance to media swelling. Comparing Comparative Examples 1-2 with Example 1, it can be seen that the addition of functional additives during the preparation of the rigid PVC pipe improved resilience and corrosion resistance, which may be due to the synergistic effect of the functional additives and the modified PVC. Comparing Comparative Example 3 with Example 1, it can be seen that the resilience and corrosion resistance were significantly reduced.

[0048] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A rigid polyvinyl chloride pipe that is corrosion-resistant and has good resilience, characterized in that... The raw materials include the following parts by weight: 100 parts modified polyvinyl chloride resin, 7-8 parts calcium carbonate, 4.5-5 parts chlorinated polyethylene, 1.3-1.5 parts calcium stearate, 3.2-3.5 parts stabilizer, 2-2.5 parts ACR resin, 0.85-0.9 parts polyethylene wax, and 1-1.2 parts stearic acid.

2. The rigid polyvinyl chloride pipe with corrosion resistance and good resilience according to claim 1, characterized in that, The stabilizer is a calcium-zinc stabilizer.

3. The rigid polyvinyl chloride pipe with corrosion resistance and good resilience according to claim 1, characterized in that, The preparation method of the modified polyvinyl chloride resin includes the following steps: Polyvinyl chloride resin was added to tetrahydrofuran and stirred to dissolve. The temperature was raised to 65-70℃, and under an inert gas atmosphere, polymethylhydrosiloxane, hexafluorobutyl acrylate, phosphate acrylate flame retardant monomer and azobisisobutyronitrile were added in sequence. The mixture was stirred evenly and reacted at 60-75℃ for 4-6 hours. The temperature was raised to 80-85℃ and held for 5 minutes. The mixture was cooled to the standard ambient temperature, and the precipitate was formed. The precipitate was filtered and washed to obtain modified polyvinyl chloride resin.

4. The rigid polyvinyl chloride pipe with corrosion resistance and good resilience according to claim 3, characterized in that, The mass ratio of polymethylhydrosiloxane, hexafluorobutyl acrylate, phosphate acrylate flame retardant monomer and azobisisobutyronitrile is 5-8:4-6:5-6:1.2-1.

5.

5. A rigid polyvinyl chloride pipe with corrosion resistance and good resilience according to claim 1, characterized in that, The corrosion-resistant and highly resilient rigid polyvinyl chloride pipe also includes functional additives. The preparation method of the functional additives includes the following steps: Under an inert gas atmosphere, hexafluoropropylene oxide trimer alcohol methacrylate, phosphorus-containing acrylate monomers, and hydroxyethyl acrylate were added to butyl acetate and stirred until homogeneous. The mixture was then heated to 65-70 °C, and a dilute solution of butyl acetate containing azobisisobutyronitrile was added dropwise. The mixture was polymerized at a constant temperature for 4-5 hours, then heated to 75 °C and held for 1.5 hours. The mixture was then subjected to reduced pressure treatment at 80 °C and a vacuum of -0.08 to -0.09 MPa. After pulverization and sieving, the functional additive was obtained.

6. A rigid polyvinyl chloride pipe with corrosion resistance and good resilience according to claim 5, characterized in that, The mass ratio of the hexafluoropropylene oxide trimer alcohol methacrylate, the phosphorus-containing acrylate monomer, and the hydroxyethyl acrylate is 100:8-10:7-8.

7. A rigid polyvinyl chloride pipe with corrosion resistance and good resilience according to claim 5, characterized in that, The mass ratio of the modified polyvinyl chloride resin to the functional additive is 100:6-9.

8. A method for preparing a corrosion-resistant and highly resilient rigid polyvinyl chloride pipe according to any one of claims 1-7, characterized in that, Includes the following steps: (1) The modified polyvinyl chloride resin, calcium carbonate, calcium stearate, chlorinated polyethylene, calcium zinc stabilizer and ACR resin are stirred at high speed and heated to 80-90°C. Polyethylene wax and stearic acid are added and the temperature is further increased to 110-120°C. The material is then transferred to a cold mixer and cooled to below 40°C to obtain a dry mixture. (2) The dry mixture is melted and plasticized at 160-190℃, extruded and sized under vacuum, cooled by spraying, cut, and inspected to obtain a corrosion-resistant and resilient rigid polyvinyl chloride pipe.

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