Anti-crack PVC buried pipe and preparation method thereof
By adding impact modifiers and modified fillers to PVC underground pipes to form a network structure, the problem of brittle cracking of PVC underground pipes under external impact loads is solved, achieving a balance between high strength and high toughness.
Patent Information
- Application Number
- CN202512029868.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-02-24
AI Technical Summary
PVC underground pipes are prone to brittle cracking when subjected to external impact loads, making it difficult to balance high strength and high toughness.
Using PVC resin as the matrix, impact modifiers and specific modified fillers are added. The surface of the inorganic filler is modified by vinyl silane, and vinyl chloride, acrylate and diallyl maleate are combined to form a network structure, which enhances the toughness and rigidity of the material.
This technology achieves high strength in PVC underground pipes while significantly improving their impact resistance and crack resistance, enhancing the material's toughness and rigidity, and preventing brittle cracking.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of plastic pipe technology, and in particular to a crack-resistant PVC underground pipe and its preparation method. Background Technology
[0002] Polyvinyl chloride (PVC) has become one of the mainstream raw materials for underground pipes due to its high mechanical strength and cost-effectiveness, and is widely used in various underground pipeline laying projects. However, PVC material itself has poor toughness, and when subjected to external impact loads (such as construction collisions, geological subsidence, etc.), the pipe body is prone to brittle cracking, leading to leakage or structural failure.
[0003] To address the brittleness of PVC pipes, current technologies typically employ the addition of elastomers, such as chlorinated polyethylene and nitrile rubber, to enhance the material's toughness. While this improves impact resistance at room temperature to some extent, the addition of elastomers also weakens the original rigidity of PVC, making it difficult to achieve the balance between high strength and high toughness required for buried pipes. Summary of the Invention
[0004] To improve the strength and toughness of PVC pipes, this application provides a crack-resistant PVC underground pipe and its preparation method.
[0005] Firstly, this application provides a crack-resistant PVC underground pipe, which adopts the following technical solution: A crack-resistant PVC underground pipe is prepared from raw materials comprising the following parts by weight: 70-85 parts PVC resin, 5-8 parts impact modifier, 5-15 parts filler, 2-4 parts heat stabilizer, 0-10 parts plasticizer, and 0.5-1.5 parts lubricant; The raw materials for preparing the filler include inorganic fillers, vinyl silane, and coating monomers, and the mass ratio of the inorganic fillers, dispersants, and coating monomers is 1:(0.05-0.1):(0.5-0.7).
[0006] By adopting the above technical solution, this invention uses PVC resin as the matrix resin, adds an impact modifier to enhance the toughness of the material, and the filler can compensate for the decrease in rigidity and strength of PVC caused by the addition of the impact modifier. Specifically, after adding the filler, the blend system exhibits obvious composite characteristics of matrix network yielding and shear yielding, mainly due to the combined effect of the impact modifier and the filler. When the material is impacted, the impact modifier releases stress through the toughening mechanism of network yielding and shear yielding, while the rigid filler particles in the filler will cause cavitation in the surrounding matrix under stress, thereby reducing the thickness of the matrix band between particles, further promoting shear yielding of the matrix, and causing the destruction of the matrix network structure to produce a large number of ligaments, thus further improving the impact performance of the blend system.
[0007] Preferably, the method for preparing the filler includes the following steps: (1) Disperse the inorganic filler uniformly in the solvent, add vinyl silane solution, stir to react, centrifuge, wash and dry after the reaction is completed to obtain the pretreated filler; (2) Add the pretreated filler, coating monomer, emulsifier, initiator and water to the reactor, stir evenly, introduce nitrogen gas, heat to react, and perform post-treatment after the reaction to obtain the filler.
[0008] By adopting the above technical solution, vinyl silane reacts with the hydroxyl groups on the surface of inorganic fillers, introducing vinyl functional groups onto their surface, thus achieving preliminary modification of the inorganic fillers, changing their surface properties, and improving their compatibility with the organic phase. Subsequently, the pretreated fillers are reacted with coating monomers in a reactor. The coating monomers polymerize under the action of an initiator and coat the surface of the pretreated fillers, further improving the dispersibility and surface properties of the inorganic fillers. After coating modification, the filler can better combine with PVC resin and other raw materials, enhancing the rigidity and toughness of the pipe, enabling crack-resistant PVC underground pipes to effectively improve impact resistance and crack resistance while maintaining high strength.
[0009] Preferably, the emulsifier is sodium dodecyl sulfate; and the initiator is azobiscyanopentanoic acid.
[0010] Preferably, the coating monomers comprise vinyl chloride, acrylate monomers and diallyl maleate in a mass ratio of 1:(0.2-0.3):(0.1-0.15).
[0011] Preferably, the acrylate monomer includes one or more of methyl methacrylate, butyl acrylate, and isooctyl acrylate.
[0012] By adopting the above technical solution, using vinyl chloride, acrylate monomers, and diallyl maleate in a specific mass ratio as coating monomers, vinyl chloride has good compatibility with PVC resin, enabling fillers to better integrate into the PVC matrix and enhancing the stability of the system; acrylate monomers have good flexibility and weather resistance, which can improve the toughness and anti-aging ability of the pipe; diallyl maleate contains multiple unsaturated double bonds, which can effectively improve the grafting efficiency during the grafting process, forming a cross-linked structure during the reaction, improving the strength and rigidity of the pipe. The three work synergistically to ensure that the prepared crack-resistant PVC underground pipe effectively improves toughness while maintaining rigidity, achieving a balance between high strength and high toughness, and enhancing the crack resistance of the pipe.
[0013] Preferably, the vinyl silane includes one or more of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriisopropoxysilane.
[0014] By adopting the above technical solution, vinyl silane is used to modify inorganic fillers. The silane portion of vinyl silane can react with the hydroxyl groups on the surface of inorganic fillers to achieve silanization modification of the fillers, promote the dispersion of filler particles, and introduce double bonds to the surface of filler particles, which facilitates subsequent polymerization and grafting reactions.
[0015] Preferably, the inorganic filler includes one or more of nano-calcium carbonate, hydrotalcite, silica, montmorillonite, and calcined kaolin.
[0016] More preferably, the inorganic filler is nano-calcium carbonate.
[0017] By adopting the above technical solution, the filler particles dispersed between the elastomers increase the distance between the elastomer molecular chains, reduce the intermolecular forces, and make it easier for the elastomer chain segments to relax, so that more impact energy can be consumed through the relaxation of the elastomer chain segments.
[0018] Preferably, the impact modifier includes one or both of CPE and ACR.
[0019] More preferably, the impact modifier comprises CPE and ACR in a mass ratio of 1:(0.1-0.3).
[0020] By adopting the above technical solution, CPE forms a complete network structure in the PVC matrix phase, which can absorb some impact energy and endow the blend system with a certain impact strength. On this basis, after adding ACR, since the ACR with core-shell structure is distributed in granular form in the PVC phase and CPE network, it can induce a large number of shear bands and crazes in the matrix, thereby further improving the impact strength of the material. Therefore, CPE and ACR show obvious synergistic effect.
[0021] Preferably, the heat stabilizer includes one or more of lead salt stabilizers, calcium-zinc composite stabilizers, and organotin stabilizers.
[0022] By adopting the above technical solutions, stabilizers can inhibit the thermal and photodegradation reactions of PVC resin during processing and use, reduce material aging due to high temperature or light exposure, and avoid problems such as decomposition and discoloration during processing.
[0023] Preferably, the plasticizer includes one or more of dioctyl phthalate, citrate, and epoxidized soybean oil.
[0024] By adopting the above technical solution, plasticizer molecules can insert into the molecular chains of PVC resin, weaken the intermolecular forces, increase the fluidity and flexibility of the molecular chains, thereby reducing the glass transition temperature of PVC resin, making the pipe easier to process during the molding process, while improving the flexibility and impact resistance of the pipe, and reducing the risk of brittle cracking when the pipe is subjected to external impact loads.
[0025] Preferably, the lubricant includes one or more of stearic acid, metal soap, ethylene bis-stearamide, solid paraffin, and polyethylene wax.
[0026] By adopting the above technical solutions, lubricants can reduce the frictional resistance of materials during processing, improve the fluidity and demolding properties of materials, and effectively enhance the stability of weather-resistant PVC inflatable films during processing.
[0027] Preferably, the PVC resin includes one of SG-5 type PVC and SG-7 type PVC.
[0028] By adopting the above technical solutions, the two types of PVC resin used to manufacture PVC underground pipes achieve a good balance in terms of strength and toughness.
[0029] Secondly, this application provides a method for preparing crack-resistant PVC underground pipes, which adopts the following technical solution: A method for preparing crack-resistant PVC underground pipe includes the following steps: PVC resin, impact modifier, filler, heat stabilizer, plasticizer, and lubricant are melt-blended, extruded and granulated, and then injection molded to obtain crack-resistant PVC underground pipes.
[0030] By adopting the above-mentioned technical solution, the preparation method of melting and blending various raw materials, extrusion granulation and injection molding can effectively utilize the characteristics of raw materials and successfully prepare buried pipes with crack resistance. This can reduce the occurrence of brittle cracking of the pipe body when subjected to external impact loads and reduce leakage or structural failure.
[0031] This application has the following beneficial effects: 1. This invention uses PVC resin as the matrix resin and adds an impact modifier to enhance the toughness of the material. The filler can compensate for the decrease in rigidity and strength of PVC caused by the addition of the impact modifier. Specifically, after adding the filler, the blend system exhibits obvious composite characteristics of matrix network yielding and shear yielding, mainly due to the combined effect of the impact modifier and the filler. When the material is subjected to impact, the impact modifier releases stress through the toughening mechanism of network yielding and shear yielding. Meanwhile, the rigid filler particles in the filler cause cavitation in the surrounding matrix under stress, thereby reducing the thickness of the interparticle matrix band, further promoting shear yielding of the matrix, and causing the destruction of the matrix network structure, resulting in a large number of ligaments, thus further improving the impact performance of the blend system.
[0032] 2. Vinyl silane reacts with the hydroxyl groups on the surface of inorganic fillers, introducing vinyl functional groups to the surface and achieving preliminary modification of the inorganic fillers. This alters the surface properties of the inorganic fillers and improves their compatibility with the organic phase. Subsequently, the pretreated fillers are reacted with coating monomers in a reactor. The coating monomers polymerize under the action of an initiator and coat the surface of the pretreated fillers, further improving the dispersibility and surface properties of the inorganic fillers. After coating modification, the filler can better combine with PVC resin and other raw materials, enhancing the rigidity and toughness of the pipe. This results in crack-resistant PVC underground pipes that, while possessing high strength, effectively improve impact resistance and crack resistance. Detailed Implementation
[0033] The present application will be further described in detail below with reference to the embodiments.
[0034] Preparation Example 1 The preparation method of the filler includes the following steps: The inorganic filler, vinyl silane, and coating monomers were weighed according to a mass ratio of 1:0.05:0.5. The inorganic filler was specifically nano-calcium carbonate with an average particle size of 40nm–80nm, purchased from Shanghai Huijingya Nanomaterials Co., Ltd. The solvent was weighed at 10 times the mass of the inorganic filler, and the solvent was an ethanol solution (ethanol:water = 3:7). The vinyl silane was specifically vinyltrimethoxysilane. An ethanol solution (ethanol:water = 3:7) was weighed at 5 times the mass of vinyltrimethoxysilane, and the vinyltrimethoxysilane was dissolved in the ethanol solution to obtain a vinyl silane solution. The coating monomers were specifically vinyl chloride, isooctyl acrylate, and diallyl maleate in a mass ratio of 1:0.2:0.1. An emulsifier was weighed at 1% of the total mass of the coating monomers, specifically sodium dodecyl sulfate. The initiator was weighed at 0.5% of the total mass of the coating monomers, specifically azodicyanovalerate.
[0035] (1) Nano-calcium carbonate was uniformly dispersed in an ethanol solution, and a vinyl silane solution was added. The mixture was stirred at 65°C for 2 hours. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the pretreated filler. (2) Premix vinyl chloride with isooctyl acrylate and heat to 35°C to obtain a premix. Add the pretreated filler, premix, diallyl maleate, sodium dodecyl sulfate, azodicyanovalerate and water to the reactor, stir evenly, introduce nitrogen gas, heat to 70°C to react, filter after the reaction, collect the filter body, wash and dry the filter body to obtain the filler.
[0036] Preparation Example 2 The preparation method of the filler includes the following steps: The inorganic filler, vinyl silane, and coating monomer were weighed according to a mass ratio of 1:0.08:0.6. The inorganic filler was specifically nano-calcium carbonate with an average particle size of 40nm–80nm, purchased from Shanghai Huijingya Nanomaterials Co., Ltd. The solvent was weighed at 10 times the mass of the inorganic filler, and the solvent was an ethanol solution (ethanol:water = 3:7). The vinyl silane was specifically vinyltriisopropoxysilane. An ethanol solution (ethanol:water = 3:7) was weighed at 5 times the mass of vinyltriisopropoxysilane, and the vinyltriisopropoxysilane was dissolved in the ethanol solution to obtain a vinyl silane solution. The coating monomer was specifically vinyl chloride, butyl acrylate, and diallyl maleate in a mass ratio of 1:0.25:0.13. An emulsifier was weighed at 1% of the total mass of the coating monomer, specifically sodium dodecyl sulfate. The initiator was weighed at 0.5% of the total mass of the coating monomer, specifically azodicyanovalerate.
[0037] (1) Nano-calcium carbonate was uniformly dispersed in an ethanol solution, and a vinyl silane solution was added. The mixture was stirred at 70°C for 2.5 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the pretreated filler. (2) Premix vinyl chloride with butyl acrylate and heat to 40°C to obtain a premix. Add the pretreated filler, premix, diallyl maleate, sodium dodecyl sulfate, azodicyanovalerate and water to the reactor, stir evenly, introduce nitrogen gas, heat to 75°C to react, filter after the reaction, collect the filter body, wash and dry the filter body to obtain the filler.
[0038] Preparation Example 3 The preparation method of the filler includes the following steps: The inorganic filler, vinyl silane, and coating monomer were weighed according to a mass ratio of 1:0.1:0.7. The inorganic filler was specifically nano-calcium carbonate with an average particle size of 40nm–80nm, purchased from Shanghai Huijingya Nanomaterials Co., Ltd. The solvent was weighed at 10 times the mass of the inorganic filler, and the solvent was an ethanol solution (ethanol:water = 3:7). The vinyl silane was specifically vinyltriethoxysilane. An ethanol solution (ethanol:water = 3:7) was weighed at 5 times the mass of vinyltriethoxysilane, and the vinyltriethoxysilane was dissolved in the ethanol solution to obtain a vinyl silane solution. The coating monomer was specifically vinyl chloride, methyl methacrylate, and diallyl maleate in a mass ratio of 1:0.3:0.15. An emulsifier was weighed at 1% of the total mass of the coating monomer, specifically sodium dodecyl sulfate. The initiator was weighed at 0.5% of the total mass of the coating monomer, specifically azodicyanovalerate.
[0039] (1) Nano-calcium carbonate was uniformly dispersed in an ethanol solution, and a vinyl silane solution was added. The mixture was stirred at 75°C for 3 hours. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the pretreated filler. (2) Premix vinyl chloride with methyl methacrylate and heat to 45°C to obtain a premix. Add the pretreated filler, premix, diallyl maleate, sodium dodecyl sulfate, azodicyanovalerate and water to the reactor, stir evenly, introduce nitrogen gas, heat to 80°C to react, filter after the reaction, collect the filter body, wash and dry the filter body to obtain the filler.
[0040] Preparation Example 4 The difference between this preparation example and preparation example 3 is that diallyl maleate is replaced by methyl methacrylate in equal mass.
[0041] Preparation Example 5 The difference between this preparation example and preparation example 3 is that the preparation method of the filler includes the following steps: Vinyl chloride and methyl methacrylate were premixed and heated to 45°C to obtain a premix. Nano-calcium carbonate, the premix, diallyl maleate, sodium dodecyl sulfate, azodicyanovalerate and water were added to a reaction vessel, stirred evenly, nitrogen gas was introduced, and the mixture was heated to 80°C to react. After the reaction was completed, the mixture was filtered, the filter body was collected, washed and dried to obtain the filler.
[0042] Preparation Example 6 The difference between this preparation example and preparation example 3 is that the preparation method of the filler includes the following steps: (1) Disperse nano-calcium carbonate uniformly in ethanol solution, add vinyl silane solution, stir and react at 75°C for 3h, centrifuge, wash and dry after reaction to obtain pretreated filler.
[0043] Example 1 The preparation method of crack-resistant PVC underground pipe includes the following steps: The raw materials are weighed according to the following proportions by weight: 70 parts PVC resin, 5 parts impact modifier, 5 parts filler, 2 parts heat stabilizer, 1 part plasticizer, and 0.5 parts lubricant. The PVC resin is specifically SG-5 type PVC resin. The impact modifier is specifically a compound of CPE and ACR in a mass ratio of 1:0.1. The filler is prepared by Preparation Example 1. The heat stabilizer is specifically tribasic lead sulfate. The plasticizer is specifically citrate ester. The lubricant is specifically stearic acid.
[0044] PVC resin, impact modifier, filler, tribasic lead sulfate, citrate, and stearic acid are added to a high-speed mixer and melt-blended at 120°C for 1 hour. The mixture is then transferred to a cold mixer to cool to 50°C. Next, the mixture is transferred to a twin-screw extruder for extrusion granulation and injection molding. The extruder barrel temperature is 240°C, the die temperature is 260°C, and the screw speed is 500 rpm to obtain crack-resistant PVC underground pipe.
[0045] Example 2 The preparation method of crack-resistant PVC underground pipe includes the following steps: Raw materials were weighed according to the following proportions by weight: 80 parts PVC resin, 6.5 parts impact modifier, 10 parts filler, 3 parts heat stabilizer, 3 parts plasticizer, and 1 part lubricant. The PVC resin was specifically SG-7 type PVC resin. The impact modifier was specifically a mixture of CPE and ACR at a mass ratio of 1:0.2. The filler was prepared according to Preparation Example 2. The heat stabilizer was specifically a calcium-zinc composite stabilizer purchased from Guangdong Weilinna New Material Technology Co., Ltd., model WWP-R03A. The plasticizer was specifically citrate ester. The lubricant was specifically ethylene bis-stearamide.
[0046] PVC resin, impact modifier, filler, calcium-zinc composite stabilizer, citrate, and ethylene bis-stearamide were added to a high-speed mixer and melt-blended at 120°C for 1 hour. The mixture was then transferred to a cold mixer and cooled to 50°C. Subsequently, the mixture was transferred to a twin-screw extruder for extrusion granulation and injection molding. The extruder barrel temperature was 243°C, the die temperature was 263°C, and the screw speed was 550 rpm, resulting in crack-resistant PVC underground pipe.
[0047] Example 3 The preparation method of crack-resistant PVC underground pipe includes the following steps: Raw materials were weighed according to the following proportions by weight: 85 parts PVC resin, 8 parts impact modifier, 15 parts filler, 4 parts heat stabilizer, 5 parts plasticizer, and 1.5 parts lubricant. The PVC resin was specifically SG-5 type PVC resin. The impact modifier was specifically a mixture of CPE and ACR at a mass ratio of 1:0.3. The filler was prepared according to Preparation Example 3. The heat stabilizer was specifically methyl mercaptan. The plasticizer was specifically epoxidized soybean oil, purchased from Shandong Hairui New Material Co., Ltd. The lubricant was specifically polyethylene wax, purchased from Wuhan Xindongyi Chemical Co., Ltd.
[0048] PVC resin, impact modifier, filler, methyl mercaptan, epoxidized soybean oil, and polyethylene wax are added to a high-speed mixer and melt-blended at 120°C for 1 hour. The mixture is then transferred to a cold mixer to cool to 50°C. Next, the mixture is transferred to a twin-screw extruder for extrusion granulation and injection molding. The extruder barrel temperature is 245°C, the die temperature is 265°C, and the screw speed is 600 rpm to obtain crack-resistant PVC underground pipe.
[0049] Example 4 The difference between this embodiment and Example 3 is that the filler prepared in Example 4 is used.
[0050] Example 5 The difference between this embodiment and Embodiment 3 is that CPE was not added; that is, ACR was used alone as the impact modifier.
[0051] Example 6 The difference between this embodiment and Embodiment 3 is that ACR was not added; that is, CPE was used alone as the impact modifier.
[0052] Comparative Example 1 The method for preparing crack-resistant PVC underground pipes differs from that in Example 3 in that the filler obtained in Preparation Example 5 is used.
[0053] Comparative Example 2 The method for preparing crack-resistant PVC underground pipes differs from that in Example 3 in that the filler obtained in Preparation Example 6 is used.
[0054] Comparative Example 3 The preparation method of crack-resistant PVC underground pipe differs from that in Example 3 in that the filler is replaced with nano-calcium carbonate.
[0055] Comparative Example 4 The preparation method of crack-resistant PVC underground pipe differs from that in Example 3 in that an impact modifier is not added, but an equal mass of filler is added instead.
[0056] Comparative Example 5 The preparation method of crack-resistant PVC underground pipe differs from that in Example 3 in that no filler is added, but an equal mass of impact modifier is added instead. Performance testing
[0057] 1. Impact resistance: The test was conducted in accordance with the national standard GB / T 1843-2008 "Determination of impact strength of plastic cantilever beam". Before the test, the sample was placed at a temperature of 23℃ and a relative humidity of 50% for 20 hours for adjustment. Notch type: Type A, 5 parallel groups, and the average value was taken.
[0058] 2. Tensile properties were tested on an ANS type tensile testing machine in accordance with GB / T 1040.1-2025 standard. The tensile specimens were type I specimens, the tensile rate was 10 mm / min, and the test temperature was room temperature.
[0059] 3. Drop hammer impact test: The test was conducted in accordance with the drop hammer impact test method (GB / T14152-2001) in the national standard GB / T5836.1-2018 "Rigid polyvinyl chloride (PVC-U) pipes for building drainage". The sample pretreatment temperature was 0℃, the drop hammer mass was 2kg, the drop height was 2m, the hammer head type was d90, the total number of impacts was 100, 6 parallel groups were formed, and the average value was taken.
[0060] 4. Ring stiffness: The ring stiffness of the samples in Examples 1-6 and Comparative Examples 1-5 were tested according to the standard in GB / T 9647-2015.
[0061] Table 1
[0062] Based on the comparison between Examples 3 and Examples 5-6, and the data in Table 1, it can be seen that the absence of CPE in Example 5 and the absence of ACR in Example 6 both affect the mechanical properties of the pipe. However, Example 3, by using CPE and ACR together, exhibits a significant synergistic effect. CPE forms a complete network structure in the PVC matrix phase, while ACR is distributed in a granular manner in both the PVC phase and the CPE network, inducing a large number of shear bands and crazes in the matrix, thereby further improving the impact strength of the material.
[0063] Based on the comparison between Example 3 and Comparative Examples 1-2 and the data in Table 1, it can be seen that: Comparative Example 1 did not perform coupling modification on the nano-calcium carbonate, resulting in poor dispersion of the nano-calcium carbonate. The subsequent coating process will further increase the particle size of the calcium carbonate, forming defect points in the resin matrix and reducing the material strength; Comparative Example 2 did not perform surface coating modification on the nano-calcium carbonate, resulting in poor compatibility with the PVC matrix and weakened interfacial bonding force. This will lead to uneven dispersion of the filler in the PVC resin, making it difficult to effectively improve the strength and toughness of the pipe.
[0064] Based on the comparison between Example 3 and Comparative Example 3, and the data in Table 1, it can be seen that directly adding unmodified nano-calcium carbonate cannot effectively improve the overall performance of PVC composite materials. Because the untreated filler surface is hydrophilic, its interfacial compatibility with PVC is poor, resulting in a two-phase separation state. The more voids and defects caused by the filler in the system, the less external force the material can withstand. In contrast, this application uses nano-calcium carbonate surface-modified with vinyl silane and coated monomers as a filler. This filler is uniformly distributed in the PVC matrix, and the particles are encapsulated by the PVC matrix, enhancing the interfacial bonding between the nano-calcium carbonate and PVC. As the number of nano-calcium carbonate particles increases, the distance between the filler particles in the PVC matrix gradually decreases, effectively forming stress transfer points and improving the tensile strength of the pipe.
[0065] Based on the comparison of Example 3 and Comparative Examples 4-5, and the data in Table 1, it can be seen that: Comparative Example 4 lacks an impact modifier, resulting in a significant deterioration in the tensile strength of the PVC material; in Comparative Example 5, although the impact modifier can significantly improve the toughness of PVC, it also leads to a decrease in the rigidity and strength of PVC. However, Example 3 of this application, through the synergistic combination of impact modifier and filler, allows the impact modifier to enhance the toughness of the material, while the filler can compensate for the decrease in the rigidity and strength of PVC caused by the addition of the impact modifier.
[0066] 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 specific 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 crack-resistant PVC underground pipe, characterized in that, It is prepared from raw materials comprising the following parts by weight: 70-85 parts PVC resin, 5-8 parts impact modifier, 5-15 parts filler, 2-4 parts heat stabilizer, 0-10 parts plasticizer, and 0.5-1.5 parts lubricant; The raw materials for preparing the filler include inorganic fillers, vinyl silane, and coating monomers, and the mass ratio of the inorganic fillers, dispersants, and coating monomers is 1:(0.05-0.1):(0.5-0.7).
2. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The method for preparing the filler includes the following steps: (1) Disperse the inorganic filler uniformly in the solvent, add vinyl silane solution, stir to react, centrifuge, wash and dry after the reaction is completed to obtain the pretreated filler; (2) Add the pretreated filler, coating monomer, emulsifier, initiator and water to the reactor, stir evenly, introduce nitrogen gas, heat to react, and perform post-treatment after the reaction to obtain the filler.
3. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The coating monomers comprise vinyl chloride, acrylate monomers, and diallyl maleate in a mass ratio of 1:(0.2-0.3):(0.1-0.15).
4. The crack-resistant PVC underground pipe according to claim 3, characterized in that, The acrylate monomers include one or more of methyl methacrylate, butyl acrylate, and isooctyl acrylate.
5. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The vinyl silane includes one or more of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriisopropoxysilane.
6. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The inorganic filler includes one or more of nano-calcium carbonate, hydrotalcite, silica, montmorillonite, and calcined kaolin.
7. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The impact modifier includes one or both of CPE and ACR.
8. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The heat stabilizer includes one or more of lead salt stabilizers, calcium-zinc composite stabilizers, and organotin stabilizers.
9. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The plasticizer includes one or more of dioctyl phthalate, citrate, and epoxidized soybean oil.
10. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The lubricant includes one or more of stearic acid, metal soap, ethylene bis-stearamide, solid paraffin, and polyethylene wax.
11. The crack-resistant PVC underground pipe according to claim 1, characterized in that, The PVC resin includes one of SG-5 type PVC and SG-7 type PVC.
12. A method for preparing a crack-resistant PVC underground pipe according to any one of claims 1-11, characterized in that, Includes the following steps: PVC resin, impact modifier, filler, heat stabilizer, plasticizer, and lubricant are melt-blended, extruded and granulated, and then injection molded to obtain crack-resistant PVC underground pipes.