Anti-scale corrosion-resistant PVC-U water intake pipe and preparation method thereof

Abstract

The invention provides an anti-scale corrosion-resistant PVC-U water intake pipe and a preparation method thereof. The water intake pipe is prepared from the following raw materials in parts by weight: 120 to 140 parts of polyvinyl chloride resin, 18 to 23 parts of modified nano oxide, 10 to 15 parts of modified nano calcium carbonate, 6 to 9 parts of polyethylene fiber, 6 to 9 parts of ethylene-acrylic acid copolymer, 10 to 16 parts of vinyl polydimethylsiloxane, 3 to 7 parts of silicon carbide, 6 to 9 parts of calcium stearate, 3 to 6 parts of zinc stearate, 3 to 6 parts of magnesium hydroxide, 2 to 5 parts of lubricant and 1 to 2 parts of ultraviolet light absorber. According to the PVC-U water intake pipe, the raw materials such as the polyvinyl chloride resin, the modified nano oxide, the modified nano calcium carbonate, the vinyl polydimethylsiloxane and the silicon carbide are compounded, so that a synergistic effect can be achieved, adhesion of dirt can be remarkably reduced, the deposition amount of incrustation scale is effectively reduced, a good anti-scaling effect is achieved, the corrosion resistance is also improved, and the service life of the PVC-U water intake pipe is prolonged. Good tensile strength and impact strength can be maintained, and the use requirements are met.

Description

Technical Field

[0001] This invention relates to the field of plastic pipe technology, and in particular to a scale-resistant and corrosion-resistant PVC-U water intake pipe and its preparation method. Background Technology

[0002] Polyvinyl chloride (PVC-U) pipes are widely used in water supply and drainage due to their advantages such as low price, high strength, good chemical stability, and easy installation. However, when used as water intake pipes to transport mineral-rich water such as groundwater and seawater over long periods, PVC-U pipes are prone to scaling, leading to reduced transport efficiency. Scale buildup also promotes bacterial growth, affecting water quality. Furthermore, the presence of acids, alkalis, and microorganisms in the water can corrode the PVC-U pipes over time, reducing their lifespan and increasing maintenance costs. Currently, to improve the corrosion and scale resistance of PVC-U water intake pipes, an anti-corrosion and anti-scaling coating is typically added inside the pipe. While this provides some protection, the coating's adhesion to the PVC-U water intake pipe is weak, making it prone to delamination and peeling. Additionally, some anti-corrosion and anti-scaling additives are added during the manufacturing process, but due to issues such as improper formulation, the anti-corrosion and anti-scaling effects remain unsatisfactory and can even negatively impact other properties of the PVC-U water intake pipe, failing to meet requirements. Summary of the Invention

[0003] In view of this, the present invention proposes an anti-scaling and corrosion-resistant PVC-U water intake pipe and its preparation method. The present invention effectively solves the scaling and corrosion problems of PVC-U water intake pipes through the synergistic effect of various raw materials.

[0004] The technical solution of this invention is implemented as follows: A scale-resistant and corrosion-resistant PVC-U water pipe comprises the following raw materials in parts by weight: 120-140 parts of polyvinyl chloride resin, 18-23 parts of modified nano-oxide, 10-15 parts of modified nano-calcium carbonate, 6-9 parts of polyethylene fiber, 6-9 parts of ethylene-acrylic acid copolymer, 10-16 parts of vinyl polydimethylsiloxane, 3-7 parts of silicon carbide, 6-9 parts of calcium stearate, 3-6 parts of zinc stearate, 3-6 parts of magnesium hydroxide, 2-5 parts of lubricant, and 1-2 parts of ultraviolet absorber.

[0005] Furthermore, the modified nano-oxide comprises nano-titanium dioxide and nano-zinc dioxide in a mass ratio of 7~9:4~6.

[0006] Furthermore, the modified nano-oxide is prepared by ultrasonically dispersing the nano-oxide in an isopropanol solution, then adding dimethyldimethoxysilane for stirring, filtering under reduced pressure, washing with deionized water, drying at 70-80°C, and pulverizing to obtain the modified nano-oxide.

[0007] Furthermore, the ratio of the nano-oxide to the isopropanol solution in g / mL is 1:4~5; the mass concentration of the isopropanol solution is 70%~80%; the mass ratio of the nano-oxide to dimethyldimethoxysilane is 1:0.1~0.2; and the ultrasonic dispersion is carried out at a temperature of 40~60℃ and an ultrasonic power of 300~400W for 10~12 minutes.

[0008] Furthermore, the lubricant is one or more of boron nitride, polydimethylsiloxane, polyethylene wax, and glyceryl monostearate; the ultraviolet absorber is one or more of ultraviolet absorber UV-P and ultraviolet absorber UV-327.

[0009] Furthermore, the modified nano-calcium carbonate comprises the following raw materials in parts by weight: 15-19 parts of CaCl2 solution, 12-16 parts of acetic acid solution, 30-36 parts of NH4HCO3 solution, 25-30 parts of chitosan quaternary ammonium salt, and 10-14 parts of isobutyltrimethoxysilane.

[0010] Furthermore, the preparation method of the modified nano-calcium carbonate is as follows: chitosan quaternary ammonium salt and acetic acid solution are stirred and mixed at 40~45℃ to obtain a sol solution, then CaCl2 solution is added and stirred to form a uniform mixture, then NH4HCO3 solution is slowly added and stirred, and the mixture is allowed to stand at room temperature for 24~26h. Then it is washed with deionized water until neutral, dried, pulverized, and then isobutyltrimethoxysilane is added and stirred to mix evenly. After drying again, the modified nano-calcium carbonate is obtained.

[0011] Furthermore, the concentration of the CaCl2 solution is 0.2-0.3 mol / L; the volume concentration of the acetic acid solution is 2%-5%; the concentration of the NH4HCO3 solution is 0.2-0.3 mol / L; and the stirring and mixing are carried out at a temperature of 40-60℃ and a stirring speed of 100-300 r / min for 20-40 min.

[0012] The preparation method of scale-resistant and corrosion-resistant PVC-U water intake pipe includes the following steps: S1. Take polyvinyl chloride resin, modified nano oxide, modified nano calcium carbonate, polyethylene fiber, ethylene-acrylic acid copolymer, vinyl polydimethylsiloxane, silicon carbide, calcium stearate, zinc stearate, magnesium hydroxide, isobutyltrimethoxysilane, lubricant, and ultraviolet absorber, mix them at low speed first, and then heat them to mix them at high speed to obtain a mixture. S2. Add the mixture to an extruder, melt-extrude, and mold to obtain a scale-resistant and corrosion-resistant PVC-U water pipe.

[0013] Furthermore, the low-speed mixing is carried out at 60~70℃ and 100~120r / min for 8~10min; the high-speed mixing is carried out at 100~120℃ and 300~400r / min for 15~20min; the extrusion temperature is 160~190℃, and the die forming temperature is 170~220℃.

[0014] Compared with the prior art, the beneficial effects of the present invention are: The PVC-U water intake pipe of this invention utilizes a compounding of raw materials such as polyvinyl chloride resin, modified nano-oxide, modified nano-calcium carbonate, polyethylene fiber, ethylene-acrylic acid copolymer, vinyl polydimethylsiloxane, silicon carbide, calcium stearate, and zinc stearate to achieve a synergistic effect. This significantly reduces the adhesion of dirt and effectively decreases the amount of scale deposited, achieving a good scale prevention effect. Its corrosion resistance is also improved, and the PVC-U water intake pipe can maintain good tensile strength and impact resistance, meeting the usage requirements.

[0015] This invention uses dimethyldimethoxysilane to modify nano-titanium dioxide and nano-zinc dioxide. While enhancing the interfacial bonding performance between the nano oxides and other raw materials, it also enhances the hydrophobicity of the PVC-U water intake pipe, effectively reducing the frictional resistance inside the pipe, thereby achieving a good anti-scaling effect. Furthermore, it can enhance the bonding force between the raw materials of the PVC-U water supply pipe to form a dense pipe, thereby effectively improving the tensile strength and impact resistance of the water intake pipe.

[0016] This invention combines chitosan quaternary ammonium salt with nano-calcium carbonate, which improves the stability of PVC-U water pipes, effectively inhibits scale formation, enhances the tensile strength and impact resistance of PVC-U water pipes, and improves their resistance to acid and alkali substances. Detailed Implementation

[0017] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0018] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0019] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0020] Example 1 A scale-resistant and corrosion-resistant PVC-U water pipe comprises the following raw materials in parts by weight: 120 parts polyvinyl chloride resin, 20 parts modified nano-oxide, 10 parts modified nano-calcium carbonate, 8 parts polyethylene fiber, 9 parts ethylene-acrylic acid copolymer, 14 parts vinyl polydimethylsiloxane, 6 parts silicon carbide, 9 parts calcium stearate, 3 parts zinc stearate, 6 parts magnesium hydroxide, 3 parts lubricant, and 2 parts ultraviolet absorber; the lubricant is composed of boron nitride and polydimethylsiloxane in a mass ratio of 1:1; the ultraviolet absorber is ultraviolet absorber UV-327; the modified nano-oxide includes nano-titanium dioxide and nano-zinc dioxide in a mass ratio of 9:5; the modified nano-calcium carbonate comprises the following raw materials in parts by weight: 18 parts CaCl2 solution, 16 parts acetic acid solution, 30 parts NH4HCO3 solution, 25 parts chitosan quaternary ammonium salt, and 14 parts isobutyltrimethoxysilane.

[0021] The modified nano-oxide is prepared as follows: The nano-oxide is ultrasonically dispersed in the isopropanol solution at a ratio of 1:4 (g / mL) to 80% (g / mL). The ultrasonic dispersion is carried out at 40°C and 400W for 12 minutes. Then, dimethyldimethoxysilane is added at a mass ratio of 1:0.1 (g / mL) and stirred. The mixture is then filtered under reduced pressure, washed with deionized water, dried at 80°C, and pulverized to obtain the modified nano-oxide.

[0022] The modified nano-calcium carbonate is prepared as follows: chitosan quaternary ammonium salt and acetic acid solution with a volume concentration of 5% are stirred and mixed at 40°C to prepare a sol solution. Then, 0.2 mol / L CaCl2 solution is added and stirred for 40 min at 60°C and 250 r / min to form a uniform mixture. Then, 0.2 mol / L NH4HCO3 solution is slowly added and stirred for 30 min at 60°C and 200 r / min. The mixture is allowed to stand at room temperature for 26 h, then washed with deionized water until neutral, dried, pulverized, and then isobutyltrimethoxysilane is added and stirred until uniform. The mixture is dried again to obtain the modified nano-calcium carbonate.

[0023] The preparation method of scale-resistant and corrosion-resistant PVC-U water intake pipe includes the following steps: S1. Take polyvinyl chloride resin, modified nano oxide, modified nano calcium carbonate, polyethylene fiber, ethylene-acrylic acid copolymer, vinyl polydimethylsiloxane, silicon carbide, calcium stearate, zinc stearate, magnesium hydroxide, isobutyltrimethoxysilane, lubricant, and ultraviolet absorber and mix them at low speed for 8 minutes at 70℃ and 100 r / min. Then, raise the temperature and mix them at high speed for 20 minutes at 110℃ and 400 r / min to obtain a mixture. S2. Add the mixture to an extruder, melt and extrude at 160°C, and mold at 190°C to obtain a PVC-U water pipe.

[0024] Example 2 A scale-resistant and corrosion-resistant PVC-U water pipe comprises the following raw materials in parts by weight: 140 parts of polyvinyl chloride resin, 19 parts of modified nano-oxide, 15 parts of modified nano-calcium carbonate, 6 parts of polyethylene fiber, 8 parts of ethylene-acrylic acid copolymer, 15 parts of vinyl polydimethylsiloxane, 6 parts of silicon carbide, 6 parts of calcium stearate, 4 parts of zinc stearate, 5 parts of magnesium hydroxide, 4 parts of lubricant, and 1 part of ultraviolet absorber; the lubricant is composed of polyethylene wax and glyceryl monostearate in a mass ratio of 2:1; the ultraviolet absorber is ultraviolet absorber UV-327; the modified nano-oxide includes nano-titanium dioxide and nano-zinc dioxide in a mass ratio of 7:4; the modified nano-calcium carbonate comprises the following raw materials in parts by weight: 19 parts of CaCl2 solution, 12 parts of acetic acid solution, 36 parts of NH4HCO3 solution, 28 parts of chitosan quaternary ammonium salt, and 10 parts of isobutyltrimethoxysilane.

[0025] The modified nano-oxide is prepared as follows: The nano-oxide is ultrasonically dispersed in the isopropanol solution at a ratio of 1:5 (g / mL) to 70% (g / mL). The ultrasonic dispersion is carried out at 60°C and 350W for 10 minutes. Then, dimethyldimethoxysilane is added at a mass ratio of 1:0.15 (g / mL), and the mixture is stirred. The mixture is then filtered under reduced pressure, washed with deionized water, dried at 75°C, and pulverized to obtain the modified nano-oxide.

[0026] The modified nano-calcium carbonate is prepared as follows: chitosan quaternary ammonium salt and acetic acid solution with a volume concentration of 3% are stirred and mixed at 45°C to prepare a sol solution. Then, 0.3 mol / L CaCl2 solution is added and stirred for 20 min at 50°C and 300 r / min to form a uniform mixture. Then, 0.3 mol / L NH4HCO3 solution is slowly added and stirred for 40 min at 50°C and 100 r / min. The mixture is allowed to stand at room temperature for 24 h, then washed with deionized water until neutral, dried, pulverized, and then isobutyltrimethoxysilane is added and stirred until uniform. The mixture is dried again to obtain the modified nano-calcium carbonate.

[0027] The preparation method of scale-resistant and corrosion-resistant PVC-U water intake pipe includes the following steps: S1. Take polyvinyl chloride resin, modified nano oxide, modified nano calcium carbonate, polyethylene fiber, ethylene-acrylic acid copolymer, vinyl polydimethylsiloxane, silicon carbide, calcium stearate, zinc stearate, magnesium hydroxide, isobutyltrimethoxysilane, lubricant, and ultraviolet absorber and mix them at low speed for 10 min at 60℃ and 120 r / min. Then, raise the temperature and mix them at high speed for 15 min at 120℃ and 300 r / min to obtain a mixture. S2. Add the mixture to an extruder, melt and extrude at 180°C, and mold at 220°C to obtain a PVC-U water pipe.

[0028] Example 3 A scale-resistant and corrosion-resistant PVC-U water pipe comprises the following raw materials in parts by weight: 136 parts of polyvinyl chloride resin, 23 parts of modified nano-oxide, 14 parts of modified nano-calcium carbonate, 9 parts of polyethylene fiber, 7 parts of ethylene-acrylic acid copolymer, 16 parts of vinyl polydimethylsiloxane, 7 parts of silicon carbide, 8 parts of calcium stearate, 5 parts of zinc stearate, 3 parts of magnesium hydroxide, 5 parts of lubricant, and 2 parts of ultraviolet absorber; the lubricant is composed of polydimethylsiloxane and polyethylene wax in a mass ratio of 2:3; the ultraviolet absorber is ultraviolet absorber UV-P; the modified nano-oxide includes nano-titanium dioxide and nano-zinc dioxide in a mass ratio of 8:6; the modified nano-calcium carbonate comprises the following raw materials in parts by weight: 15 parts of CaCl2 solution, 14 parts of acetic acid solution, 34 parts of NH4HCO3 solution, 30 parts of chitosan quaternary ammonium salt, and 12 parts of isobutyltrimethoxysilane.

[0029] The modified nano-oxide is prepared as follows: The nano-oxide is ultrasonically dispersed in the isopropanol solution at a ratio of 1:4 (g / mL) to 75% (g / mL) and a concentration of 300W. The ultrasonic dispersion is carried out at 50°C and 300W for 11 minutes. Then, dimethyldimethoxysilane is added at a mass ratio of 1:0.2 (g / mL) and stirred. The mixture is then filtered under reduced pressure, washed with deionized water, dried at 70°C, and pulverized to obtain the modified nano-oxide.

[0030] The modified nano-calcium carbonate is prepared as follows: chitosan quaternary ammonium salt and acetic acid solution with a volume concentration of 4% are mixed at 40°C to prepare a sol solution. Then, a CaCl2 solution with a concentration of 0.3 mol / L is added and stirred for 30 minutes at a temperature of 55°C and a stirring speed of 200 r / min to form a uniform mixture. Then, a NH4HCO3 solution with a concentration of 0.25 mol / L is slowly added and stirred for 20 minutes at a temperature of 40°C and a stirring speed of 150 r / min. The mixture is allowed to stand at room temperature for 25 hours, then washed with deionized water until neutral, dried, pulverized, and then isobutyltrimethoxysilane is added and stirred until uniform. The mixture is dried again to obtain the modified nano-calcium carbonate.

[0031] The preparation method of scale-resistant and corrosion-resistant PVC-U water intake pipe includes the following steps: S1. Take polyvinyl chloride resin, modified nano oxide, modified nano calcium carbonate, polyethylene fiber, ethylene-acrylic acid copolymer, vinyl polydimethylsiloxane, silicon carbide, calcium stearate, zinc stearate, magnesium hydroxide, isobutyltrimethoxysilane, lubricant, and ultraviolet absorber and mix them at low speed for 9 minutes at 65°C and 110 r / min. Then, heat the mixture to 120°C and mix it at high speed for 18 minutes at 350 r / min to obtain a mixture. S2. Add the mixture to an extruder, melt and extrude at 170°C, and mold at 200°C to obtain a PVC-U water pipe.

[0032] Comparative Example 1 The difference between this comparative example and Example 3 is that the raw material ratio of the PVC-U water pipe is different, while the rest is the same as Example 3.

[0033] The scale-resistant and corrosion-resistant PVC-U water pipe of this comparative proportion includes the following raw materials in parts by weight: 136 parts of polyvinyl chloride resin, 9 parts of modified nano oxide, 6 parts of modified nano calcium carbonate, 23 parts of polyethylene fiber, 20 parts of ethylene-acrylic acid copolymer, 16 parts of vinyl polydimethylsiloxane, 3 parts of silicon carbide, 15 parts of calcium stearate, 1 part of zinc stearate, 3 parts of magnesium hydroxide, 1 part of lubricant, and 2 parts of ultraviolet absorber.

[0034] Comparative Example 2 The difference between this comparative example and Example 3 is that the modified nano-oxide is replaced with simple nano-titanium dioxide, while the rest remains the same as in Example 3.

[0035] The scale-resistant and corrosion-resistant PVC-U water pipe comprises the following raw materials in parts by weight: 136 parts polyvinyl chloride resin, 23 parts nano titanium dioxide, 14 parts modified nano calcium carbonate, 9 parts polyethylene fiber, 7 parts ethylene-acrylic acid copolymer, 16 parts vinyl polydimethylsiloxane, 7 parts silicon carbide, 8 parts calcium stearate, 5 parts zinc stearate, 3 parts magnesium hydroxide, 5 parts lubricant, and 2 parts ultraviolet absorber.

[0036] Comparative Example 3 The difference between this comparative example and Example 3 is that the raw material of the PVC-U water pipe does not contain modified nano-oxides, while the rest is the same as in Example 3.

[0037] The scale-resistant and corrosion-resistant PVC-U water pipe comprises the following raw materials in parts by weight: 136 parts polyvinyl chloride resin, 14 parts modified nano calcium carbonate, 9 parts polyethylene fiber, 7 parts ethylene-acrylic acid copolymer, 16 parts vinyl polydimethylsiloxane, 7 parts silicon carbide, 8 parts calcium stearate, 5 parts zinc stearate, 3 parts magnesium hydroxide, 5 parts lubricant, and 2 parts ultraviolet absorber.

[0038] Comparative Example 4 The difference between this comparative example and Example 3 is that the raw material of the PVC-U water pipe does not contain modified nano-calcium carbonate, while the rest is the same as in Example 3.

[0039] The scale-resistant and corrosion-resistant PVC-U water pipe comprises the following raw materials in parts by weight: 136 parts polyvinyl chloride resin, 23 parts modified nano oxide, 9 parts polyethylene fiber, 7 parts ethylene-acrylic acid copolymer, 16 parts vinyl polydimethylsiloxane, 7 parts silicon carbide, 8 parts calcium stearate, 5 parts zinc stearate, 3 parts magnesium hydroxide, 5 parts lubricant, and 2 parts ultraviolet absorber.

[0040] The performance of the PVC-U water intake pipes prepared in Examples 1-3 and Comparative Examples 1-4 above was tested.

[0041] (1) Anti-scaling performance The PVC-U water pipes prepared in Examples 1-3 and Comparative Examples 1-4 were used as samples and placed in a simulated scale solution (containing 500 mg / mL calcium sulfate, 200 mg / mL calcium phosphate and 1000 mg / L calcium carbonate). After soaking at 60°C for 30 days, the samples were taken out, rinsed with deionized water, dried, and weighed to calculate the scale content and scale deposition amount.

[0042] (2) Tensile strength The test was conducted in accordance with GB / T 8804.2-2003 "Determination of tensile properties of thermoplastic pipes - Part 2: Rigid polyvinyl chloride (PVC-U), chlorinated polyvinyl chloride (PVC-C) and high-impact polyvinyl chloride (PVC-HI) pipes".

[0043] (3) Impact strength The test was conducted in accordance with the requirements of the drop hammer test in GB / T 10002.1-2023 "Rigid Polyvinyl Chloride (PVC-U) Pipes for Water Supply".

[0044] (4) Corrosion resistance The PVC-U water pipe samples of Examples 1-3 and Comparative Examples 1-4 were immersed in hydrochloric acid solution with pH 3 and sodium hydroxide solution with pH 11 respectively at room temperature for 30 days. The samples were then removed, and the tensile strength of the PVC-U water pipe samples before and after immersion was measured. The strength retention rate was then calculated.

[0045] Strength retention rate % = (Tensile strength before immersion - Tensile strength after immersion) / Tensile strength before immersion × 100% The performance test results are shown in Table 1 below.

[0046] Table 1 Performance test results of PVC-U water intake pipes

[0047] The above results indicate that the PVC-U water intake pipes of Examples 1-3 of this invention, through appropriate raw material ratios and the use of reasonable modified nano-oxides and modified nano-calcium carbonate, can effectively achieve good anti-scaling and anti-corrosion performance while improving the tensile strength and impact strength of the PVC-U water intake pipe. Compared with Example 3, the raw material ratios of the PVC-U water intake pipe in Comparative Example 1 are different; the modified nano-oxides in the raw materials of Comparative Example 2 are replaced with simple nano-titanium dioxide; the raw materials of Comparative Example 3 do not contain modified nano-oxides; and the raw materials of Comparative Example 4 do not contain modified nano-calcium carbonate. These factors result in the various components in the raw materials failing to form a good synergistic effect, leading to a decrease in the anti-scaling and anti-corrosion performance of the prepared PVC-U water intake pipe, and also affecting its tensile strength and impact strength.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A scale-resistant and corrosion-resistant PVC-U water intake pipe, characterized in that, The raw materials include the following parts by weight: 120-140 parts of polyvinyl chloride resin, 18-23 parts of modified nano-oxide, 10-15 parts of modified nano-calcium carbonate, 6-9 parts of polyethylene fiber, 6-9 parts of ethylene-acrylic acid copolymer, 10-16 parts of vinyl polydimethylsiloxane, 3-7 parts of silicon carbide, 6-9 parts of calcium stearate, 3-6 parts of zinc stearate, 3-6 parts of magnesium hydroxide, 2-5 parts of lubricant, and 1-2 parts of ultraviolet absorber.

2. The scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 1, characterized in that, The modified nano-oxide comprises nano-titanium dioxide and nano-zinc dioxide in a mass ratio of 7~9:4~6.

3. The scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 1, characterized in that, The modified nano-oxide is prepared by ultrasonically dispersing the nano-oxide in an isopropanol solution, then adding dimethyldimethoxysilane and stirring, filtering under reduced pressure, washing with deionized water, drying at 70~80℃, and pulverizing to obtain the modified nano-oxide.

4. The scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 3, characterized in that, The ratio of nano-oxide to isopropanol solution (g / mL) is 1:4~5; the mass concentration of isopropanol solution is 70%~80%; the mass ratio of nano-oxide to dimethyldimethoxysilane is 1:0.1~0.2; the ultrasonic dispersion is carried out at a temperature of 40~60℃ and an ultrasonic power of 300~400W for 10~12 minutes.

5. The scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 1, characterized in that, The lubricant is one or more of boron nitride, polydimethylsiloxane, polyethylene wax, and glyceryl monostearate; the ultraviolet absorber is one or more of ultraviolet absorber UV-P and ultraviolet absorber UV-327.

6. The scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 1, characterized in that, The modified nano-calcium carbonate comprises the following raw materials in parts by weight: 15-19 parts CaCl2 solution, 12-16 parts acetic acid solution, 30-36 parts NH4HCO3 solution, 25-30 parts chitosan quaternary ammonium salt, and 10-14 parts isobutyltrimethoxysilane.

7. The scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 6, characterized in that, The modified nano-calcium carbonate is prepared by: mixing chitosan quaternary ammonium salt with acetic acid solution at 40-45℃ to obtain a sol solution, then adding CaCl2 solution and stirring to form a uniform mixture, then slowly adding NH4HCO3 solution and stirring to mix, letting it stand at room temperature for 24-26 hours, then washing with deionized water until neutral, drying, pulverizing, then adding isobutyltrimethoxysilane and stirring to mix evenly, and drying again to obtain modified nano-calcium carbonate.

8. The scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 7, characterized in that, The concentration of the CaCl2 solution is 0.2-0.3 mol / L; the volume concentration of the acetic acid solution is 2%-5%; the concentration of the NH4HCO3 solution is 0.2-0.3 mol / L; the stirring and mixing are carried out at a temperature of 40-60℃ and a stirring speed of 100-300 r / min for 20-40 min.

9. The method for preparing the scale-resistant and corrosion-resistant PVC-U water intake pipe according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Take polyvinyl chloride resin, modified nano oxide, modified nano calcium carbonate, polyethylene fiber, ethylene-acrylic acid copolymer, vinyl polydimethylsiloxane, silicon carbide, calcium stearate, zinc stearate, magnesium hydroxide, isobutyltrimethoxysilane, lubricant, and ultraviolet absorber, mix them at low speed first, and then heat them to mix them at high speed to obtain a mixture. S2. Add the mixture to an extruder, melt-extrude, and mold to obtain a scale-resistant and corrosion-resistant PVC-U water pipe.

10. The method for preparing the scale-resistant and corrosion-resistant PVC-U water intake pipe according to claim 9, characterized in that, The low-speed mixing is carried out at 60~70℃ and 100~120r / min for 8~10min; the high-speed mixing is carried out at 100~120℃ and 300~400r / min for 15~20min; the extrusion temperature is 160~190℃, and the die forming temperature is 170~220℃.

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