Composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes

Abstract

The present application relates to the technical field of pipeline drainage, and particularly relates to a composite hydrophobic material for inhibiting crystallization of a tunnel drainage pipeline and a preparation method thereof; the composite hydrophobic material comprises a hydrophobic inner layer and a scale inhibition outer layer attached to the outer surface of the hydrophobic inner layer; the hydrophobic inner layer comprises tetrahydrofuran, a solvent volatilizing agent, a surfactant, nano-silicon dioxide, a cross-linking agent and a curing agent; the scale inhibition outer layer comprises a scale inhibitor solution and a gum material, wherein the scale inhibitor solution comprises EDTA, hydrolyzed maleic anhydride and sulfamic acid; the preparation method comprises the following steps: S1, coating the hydrophobic inner layer material; S2, air-drying to obtain the hydrophobic inner layer; S3, coating the scale inhibition outer layer material on the surface of the hydrophobic inner layer to obtain the composite material; the composite material prepared by the present application still has excellent hydrophobic performance after being left for 24 hours and can be maintained for a long time; the scale inhibition outer layer protects the hydrophobic inner layer and simultaneously plays a scale inhibition role, thereby improving the functionality of the material.

Description

Technical Field

[0001] This invention relates to the field of pipeline drainage technology, specifically to a composite hydrophobic material that inhibits crystallization in tunnel drainage pipes. Background Technology

[0002] Analysis of tunnel water samples revealed that Ca 2+ Mg 2+ The average concentrations were only 16.46 mg / L and 8.67 mg / L, respectively, for HCO3-. 3- The average concentration is as high as 208 mg / L. The low water flow velocity within the drainage pipes creates conditions for the easy-to-crystallize ions to come into full contact; furthermore, the slightly alkaline water also promotes crystal formation. Therefore, with prolonged use, crystallization and blockage can easily occur inside the tunnel drainage pipes, thus affecting drainage efficiency.

[0003] To address the common problem of tunnel crystallization and blockage during tunnel construction and operation, this application develops a novel composite hydrophobic material to inhibit the formation of crystals. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes.

[0005] A composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes includes a hydrophobic inner layer for coating on the inner wall of the pipe and a scale-inhibiting outer layer attached to the outer surface of the hydrophobic inner layer.

[0006] The hydrophobic inner layer comprises, by volume mass ratio, 4.5–5.5:6:0.05:1:1:0.02 tetrahydrofuran: solvent volatile agent: surfactant: nano silica: crosslinking agent: curing agent;

[0007] The scale-inhibiting outer layer comprises, by mass-volume ratio: a scale inhibitor solution and a colloidal material in a ratio of 1 to 1.5:5, wherein the scale inhibitor solution comprises, by mass ratio: EDTA: hydrolyzed maleic anhydride: aminosulfonic acid in a ratio of 4:3:0.5 to 0.6.

[0008] Furthermore, the surfactant is a silane coupling agent, and the solvent volatile agent is isopropanol.

[0009] Note: When the surfactant is a silane coupling agent, the final composite material still has excellent hydrophobic properties after standing for 24 hours and can maintain them for a long time; when an appropriate proportion of isopropanol is added, the droplet rolling speed when water flows through the composite material is optimal.

[0010] Furthermore, the crosslinking agent is RTV-2 silicone rubber, and the curing agent is DOP.

[0011] Note: RTV-2 silicone rubber can maintain its elasticity in a temperature range of -60 to 200℃ after curing, making it suitable for high-temperature environments. It provides a stable, easy-to-use, environmentally friendly and harmless material option.

[0012] Furthermore, the gel material comprises, by mass ratio: polyvinyl alcohol: sodium alginate in a ratio of 1:0.1.

[0013] Note: Polyvinyl alcohol and sodium alginate have more stable compatibility and solubility when mixed, without causing additional crystallization burden, and can give the scale inhibitor solution a certain mechanical strength.

[0014] Further, the preparation method of the hydrophobic inner layer is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are first mixed to obtain solution A, then nano-silica and surfactant are added to solution A in sequence and stirred for 4-6 min to obtain solution B, then RTV-2 crosslinking agent and curing agent are added to solution B in sequence and stirred for 9-11 min to obtain hydrophobic inner layer material.

[0015] Note: After applying the above hydrophobic inner layer material to the surface of the square piece and allowing it to stand for 24 hours, the contact angle was measured to be 130.63° and the roll-off angle to be 8.110°, indicating that the hydrophobic inner layer has excellent hydrophobic properties.

[0016] Furthermore, the preparation method of the scale inhibitor outer layer is as follows: first, the raw materials of the scale inhibitor solution are mixed in proportion to obtain the scale inhibitor solution, then the colloidal material is added into the scale inhibitor solution in proportion, and then dissolved and stirred in a water bath at 92-98°C for 0.4-0.6 hours. After the dissolution and stirring are completed, the scale inhibitor outer layer material is obtained.

[0017] Note: The calcium carbonate crystals in the pipeline are due to the presence of Ca in the alkaline environment. 2+ and HCO 3- The reaction produces it. By selecting a suitable scale inhibitor and adding a certain amount of colloidal material to make it slow-release, it reacts with the calcium in the water. 2+ and HCO 3- The reaction slowly releases the reagent, reducing the amount of crystals formed.

[0018] Furthermore, the hydrophobic inner layer also includes low-temperature expanding particles and hydrophobic microspheres;

[0019] The hydrophobic inner layer is prepared by mixing tetrahydrofuran and solvent volatile agent at room temperature to obtain solution A, and then dividing solution A into two equal parts.

[0020] The low-temperature expanding particles were then dispersed in one part of solution A at a solid-liquid ratio of 1:1 to 2 for 8 to 10 minutes using ultrasound to obtain solution C1. The hydrophobic microspheres were then dispersed in another part of solution A at a solid-liquid ratio of 1:4 to 6 for 8 to 10 minutes using ultrasound to obtain solution C2.

[0021] Then, nano-silica and surfactant are added to solution C1 and stirred for 4-6 minutes to obtain solution D. Crosslinking agent and curing agent are added to solution D and stirred for 9-11 minutes. The solution is then semi-cured at 80-90℃ for 15-25 minutes to obtain semi-cured material. The semi-cured material is then impregnated in solution C2 and completely cured at 100-105℃ to obtain hydrophobic inner layer material B.

[0022] The outer shell of the hydrophobic microspheres is made of silicone rubber, and the core of the hydrophobic microspheres is filled with polydimethylsiloxane mucus. The diameter of the hydrophobic microspheres is 3-5 μm, and the thickness of the outer shell is 20-30% of the diameter. The low-temperature expanding particles include 2-3 parts of expanded perlite, 10-20 parts of sodium acrylate, 5-7 parts of sodium chloride, and 0.4-0.5 parts of isopropyl cyanoacetate by weight. The diameter of the low-temperature expanding particles is 40-50 μm.

[0023] Explanation: In low-temperature environments, water in the pipes will condense and form ice, which can easily lead to crystallization or freezing in the pipes, thus affecting the drainage effect. Therefore, this application adds low-temperature expansion particles to the hydrophobic inner layer material. In low-temperature environments such as winter, the low-temperature expansion particles expand, thereby increasing the contact area between the hydrophobic inner layer material and the inner wall of the pipe, thereby improving the anti-icing effect. In addition, due to the addition of hydrophobic microspheres, the expansion of the low-temperature expansion particles will squeeze the hydrophobic microspheres and expel the polydimethylsiloxane viscous liquid inside them, thereby further improving the hydrophobic effect and thus further enhancing the anti-crystallization effect.

[0024] Furthermore, the hydrophobic inner layer comprises a first hydrophobic inner layer material and a second hydrophobic inner layer material in a mass ratio of 1:0.5 to 1.5.

[0025] The preparation method of the first hydrophobic inner layer material is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are mixed to obtain solution A, and then nano-silica and surfactant are added to solution A in sequence and stirred for 4 to 6 minutes to obtain solution B. Then, crosslinking agent and curing agent are added to solution B in sequence and stirred for 9 to 11 minutes. After stirring, the first hydrophobic inner layer material is obtained.

[0026] The preparation method of the second hydrophobic inner layer material is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are first mixed to obtain solution A, and solution A is divided into 2 equal parts;

[0027] The low-temperature expanding particles were then dispersed in one part of solution A at a solid-liquid ratio of 1:1 to 2 for 8 to 10 minutes using ultrasound to obtain solution C1. The hydrophobic microspheres were then dispersed in another part of solution A at a solid-liquid ratio of 1:4 to 6 for 8 to 10 minutes using ultrasound to obtain solution C2.

[0028] Next, nano-silica and surfactant are added to solution C1 and stirred for 4-6 minutes to obtain solution D. Crosslinking agent and curing agent are added to solution D and stirred for 9-11 minutes. The solution is then semi-cured at 80-90℃ for 15-25 minutes to obtain a semi-cured material. The semi-cured material is then impregnated in solution C2 and completely cured at 100-105℃ to obtain the second hydrophobic inner layer material.

[0029] Note: The first and second hydrophobic inner layer materials have similar compositions, which helps to reduce the contact area and increase the surface contact angle, thereby enhancing the rolling properties of water droplets on the surface and making it easier for water droplets to roll off the pipe surface, achieving a better hydrophobic effect.

[0030] The preparation method of the composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes, as described above, includes the following steps:

[0031] S1. First, coat the inner wall of the pipe with a hydrophobic inner layer material with a thickness of ≤0.03cm;

[0032] S2. The hydrophobic inner layer material is dried to obtain the hydrophobic inner layer.

[0033] S3. Then, coat the outer surface of the hydrophobic inner layer with a scale-inhibiting outer layer material with a thickness of 0.15-0.25cm, and dry it to obtain the composite material.

[0034] The preparation method of the composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes, as described above, includes the following steps:

[0035] S1. First, coat the inner wall of the pipe with a second hydrophobic inner layer material with a thickness of ≤0.03cm. The coating method is to take any point corresponding to the center of the pipe as the center point, and then coat multiple paths outward from the center point, and the end point of the path returns to the center point. After coating, use a light dryer to dry and cure at 75-85℃ for 5-10 minutes.

[0036] S2. After the second hydrophobic inner layer material has dried, coat the inner wall of the pipe with a first hydrophobic inner layer material with a thickness of ≤0.03cm in the blank area between the second hydrophobic inner layer material. Dry it in a hot air drying oven at 65-75℃ for 20-30 minutes to obtain the hydrophobic inner layer.

[0037] S3. Apply another layer of scale-inhibiting outer material with a thickness of 0.15-0.25 cm to obtain the composite material.

[0038] Explanation: The second hydrophobic inner layer material is formed into multiple paths, which are the umbrella ribs, and the first hydrophobic inner layer material forms the base, which is the umbrella surface, thus obtaining an umbrella-like structure. This structure helps to reduce the contact area and increase the surface contact angle, thereby enhancing the rolling property of water droplets on the surface and making it easier for water droplets to roll off the pipe surface, achieving a better hydrophobic effect. Moreover, the first and second hydrophobic inner layer materials have similar compositions, and the two are tightly bonded under the action of hot air drying, thus forming a stable umbrella-like structure. Then, a scale-inhibiting outer layer is coated on the surface of the hydrophobic inner layer of the umbrella-like structure. Because the surface of the umbrella ribs is not flat, the bonding surface between the hydrophobic inner layer and the scale-inhibiting outer layer can be regarded as wavy rather than straight, which further enhances the bonding strength of the composite material.

[0039] Compared with existing hydrophobic materials, the beneficial effects of this invention are:

[0040] (1) When tetrahydrofuran and isopropanol are mixed, the droplet rolling speed is optimal when draining water. When the surfactant is a silane coupling agent, it still has excellent hydrophobic properties after standing for 24 hours and can maintain them for a long time. When nano-silica is used as a thickening and reinforcing agent, the hydrophobic material surface is uniformly dispersed, the material does not stick together and there is no obvious uneven texture, which is more conducive to the droplet rolling without staying on the contact surface. After RTV-2 silicone rubber is cured, it can maintain elasticity in the temperature range of -60 to 200℃. The prepared hydrophobic inner layer has excellent hydrophobic properties.

[0041] (2) In order to inhibit the formation of calcium carbonate crystals in an alkaline environment, this application selects EDTA, aminosulfonic acid and hydrolyzed maleic anhydride as scale inhibitors and polyvinyl alcohol and sodium alginate as colloidal materials. The scale inhibitor solvent and colloidal materials are mixed to have more stable compatibility and solubility, without causing additional crystallization burden, and can give the scale inhibitor solution a certain mechanical strength, protect the hydrophobic inner layer while playing a scale inhibition role, and improve the functionality of the material.

[0042] (3) This application adds low-temperature expansion particles to the hydrophobic inner layer material, so that the low-temperature expansion particles expand in low-temperature environments such as winter, thereby increasing the contact area between the hydrophobic inner layer material and the inner wall of the pipe, thus improving the anti-icing effect. In addition, due to the addition of hydrophobic microspheres, the low-temperature expansion particles will squeeze the hydrophobic microspheres while expanding, causing the polydimethylsiloxane viscous liquid inside the hydrophobic microspheres to be discharged, thereby further improving the hydrophobic effect and thus further improving the anti-crystallization effect. The hydrophobic inner layer material B with added low-temperature expansion particles and the hydrophobic inner layer material A without added expansion particles are arranged in an umbrella-like structure. This structure helps to reduce the contact area and increase the surface contact angle, thereby enhancing the rolling property of water droplets on the surface, making it easier for water droplets to roll off the pipe surface, achieving a better hydrophobic effect. The low-temperature expansion particles will expand in low-temperature environments, which helps to prevent the formation and adhesion of ice crystals, thereby reducing the damage of freezing to drainage pipes and extending their service life. Attached Figure Description

[0043] Figure 1 This is a diagram showing the experimental results of the composite hydrophobic material of the present invention, compared with Example 1;

[0044] Figure 2 This is an experimental example of the anti-crystallization results of the composite hydrophobic material of the present invention, Example 1;

[0045] Figure 3 This is a scale inhibition result diagram of Example 1 of the experimental case of the composite hydrophobic material of the present invention;

[0046] Figure 4 This is an experimental example, Example 2, of the anti-crystallization results of the composite hydrophobic material of the present invention. Detailed Implementation

[0047] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0048] Example 1: A composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes, comprising a hydrophobic inner layer for coating on the inner wall of the pipe and a scale-inhibiting outer layer attached to the outer surface of the hydrophobic inner layer;

[0049] The hydrophobic inner layer comprises, by volume mass ratio, tetrahydrofuran: solvent volatiles: surfactant: nano-silica: crosslinking agent: curing agent in a ratio of 5:6:0.05:1:1:0.02; the surfactant is a silane coupling agent, the solvent volatiles are isopropanol, the crosslinking agent is RTV-2 silicone rubber, and the curing agent is DOP.

[0050] The preparation method of the hydrophobic inner layer is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are first mixed to obtain solution A, then nano silica and surfactant are added to solution A in sequence and stirred for 5 min in sequence to obtain solution B, then RTV-2 crosslinking agent and curing agent are added to solution B in sequence and stirred for 10 min in sequence. After stirring is completed, the hydrophobic inner layer material is obtained.

[0051] The scale-inhibiting outer layer comprises, by mass-volume ratio: a scale inhibitor solution and a colloidal material in a ratio of 1.25:5, wherein the scale inhibitor solution comprises, by mass ratio: EDTA: hydrolyzed maleic anhydride: aminosulfonic acid in a ratio of 4:3:0.55; and the colloidal material comprises, by mass ratio: polyvinyl alcohol: sodium alginate in a ratio of 1:0.1.

[0052] The preparation method of the scale inhibitor outer layer is as follows: first, the raw materials of the scale inhibitor solution are mixed in proportion to obtain the scale inhibitor solution, then the colloidal material is added into the scale inhibitor solution in proportion, and then dissolved and stirred in a water bath at 95°C for 0.5 hours. After the dissolution and stirring are completed, the scale inhibitor outer layer material is obtained.

[0053] Example 2: A method for preparing a composite hydrophobic material that inhibits crystallization in tunnel drainage pipes, comprising the following steps:

[0054] S1. First, coat the inner wall of the pipe with a layer of hydrophobic inner layer material with a thickness of 0.03 cm prepared in Example 1;

[0055] S2. The mixed hydrophobic inner layer material is dried to obtain the hydrophobic inner layer.

[0056] S3. Then, coat the outer surface of the hydrophobic inner layer with a scale-inhibiting outer layer material with a thickness of 0.20cm, and dry it to obtain the composite material.

[0057] Example 3: This example differs from Example 1 in that the hydrophobic inner layer comprises, by volume mass ratio, 4.5:6:0.05:1:1:0.02 tetrahydrofuran: solvent volatile agent: surfactant: nano silica: crosslinking agent: curing agent.

[0058] Example 4: This example differs from Example 1 in that the hydrophobic inner layer comprises, by volume mass ratio, 5.5:6:0.05:1:1:0.02 tetrahydrofuran: solvent volatile agent: surfactant: nano silica: crosslinking agent: curing agent.

[0059] Example 5: This example differs from Example 1 in that the scale inhibitor outer layer comprises, by mass-volume ratio, a scale inhibitor solution and a colloidal material in a 1:5 ratio.

[0060] Example 6: This example differs from Example 1 in that the scale inhibitor outer layer comprises, by mass-volume ratio, a scale inhibitor solution and a colloidal material in a ratio of 1.5:5.

[0061] Example 7: The difference between this example and Example 1 is that the scale inhibitor solution comprises, by mass ratio: EDTA: hydrolyzed maleic anhydride: aminosulfonic acid in a ratio of 4:3:0.5.

[0062] Example 8: The difference between this example and Example 1 is that the scale inhibitor solution comprises, by mass ratio: EDTA: hydrolyzed maleic anhydride: aminosulfonic acid in a ratio of 4:3:0.6.

[0063] Example 9: The difference between this example and Example 1 is that the preparation method of the hydrophobic inner layer is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are first mixed to obtain solution A, then nano silica and surfactant are added to solution A in sequence and stirred for 4 min to obtain solution B, then RTV-2 crosslinking agent and curing agent are added to solution B in sequence and stirred for 9 min.

[0064] Example 10: The difference between this example and Example 1 is that the preparation method of the hydrophobic inner layer is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are first mixed to obtain solution A, then nano silica and surfactant are added to solution A in sequence and stirred for 6 min to obtain solution B, then RTV-2 crosslinking agent and curing agent are added to solution B in sequence and stirred for 11 min.

[0065] Example 11: The difference between this example and Example 1 is that the gel material is added to the scale inhibitor solution in proportion, and then dissolved and stirred in a water bath at 92°C for 0.4 hours.

[0066] Example 12: The difference between this example and Example 1 is that the gel material is added to the scale inhibitor solution in proportion, and then dissolved and stirred in a water bath at 98°C for 0.6 hours.

[0067] Example 13: This example differs from Example 1 in that the hydrophobic inner layer further includes low-temperature expanding particles and hydrophobic microspheres; the preparation method of the hydrophobic inner layer is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are first mixed to obtain solution A, and solution A is divided into 2 equal parts;

[0068] The low-temperature expanding particles were then dispersed in one part of solution A at a solid-liquid ratio of 1:1.5 for 9 minutes using ultrasound to obtain solution C1. The hydrophobic microspheres were then dispersed in another part of solution A at a solid-liquid ratio of 1:5 for 9 minutes using ultrasound to obtain solution C2. The ultrasound power was 50 kHz.

[0069] Then, nano-silica and surfactant are added to solution C1 and stirred for 5 minutes to obtain solution D. Crosslinking agent and curing agent are added to solution D and stirred for 10 minutes. The solution is then semi-cured at 85°C for 20 minutes to obtain a semi-cured material. The semi-cured material is then impregnated in solution C2 and completely cured at 103°C to obtain a hydrophobic inner layer material.

[0070] The outer shell of the hydrophobic microspheres is made of silicone rubber, and the core of the hydrophobic microspheres is filled with polydimethylsiloxane viscous. The diameter of the hydrophobic microspheres is 4 μm, and the thickness of the outer shell is 25% of the diameter. The low-temperature expanding particles, by weight, include 2.5 parts expanded perlite, 15 parts sodium acrylate, 6 parts sodium chloride, and 0.45 parts isopropyl cyanoacetate. The diameter of the low-temperature expanding particles is 45 μm.

[0071] Example 14: The difference between this example and Example 13 is that the low-temperature expansion particles are dispersed in solution A at a solid-liquid ratio of 1:1 for 8 minutes using ultrasound to obtain solution C1.

[0072] Example 15: The difference between this example and Example 13 is that the low-temperature expansion particles are dispersed in solution A at a solid-liquid ratio of 1:2 for 10 minutes using ultrasound to obtain solution C1.

[0073] Example 16: The difference between this example and Example 13 is that the hydrophobic microspheres were dispersed in solution A at a solid-liquid ratio of 1:4 for 8 minutes using ultrasound to obtain solution C2.

[0074] Example 17: The difference between this example and Example 13 is that hydrophobic microspheres are dispersed in solution A at a solid-liquid ratio of 1:6 for 10 minutes using ultrasound to obtain solution C2.

[0075] Example 18: The difference between this example and Example 13 is that the material is semi-cured at 80°C for 15 minutes to obtain a semi-cured material, and then the semi-cured material is impregnated in C2 solution and completely cured at 100°C to obtain a hydrophobic inner layer material.

[0076] Example 19: The difference between this example and Example 13 is that the material is semi-cured at 90°C for 25 minutes to obtain a semi-cured material, and then the semi-cured material is impregnated in C2 solution and completely cured at 105°C to obtain a hydrophobic inner layer material.

[0077] Example 20: This example differs from Example 13 in that the diameter of the hydrophobic microspheres is 3 μm and the thickness of the shell is 30% of the diameter.

[0078] Example 21: This example differs from Example 13 in that the diameter of the hydrophobic microspheres is 5 μm and the thickness of the shell is 20% of the diameter.

[0079] Example 22: This example differs from Example 13 in that the low-temperature expanding particles, by weight, include 2 parts expanded perlite, 20 parts sodium acrylate, 7 parts sodium chloride, and 0.5 parts isopropyl cyanoacetate, and the diameter of the low-temperature expanding particles is 40 μm.

[0080] Example 23: This example differs from Example 13 in that the low-temperature expanding particles, by weight, include 3 parts expanded perlite, 10 parts sodium acrylate, 5 parts sodium chloride, and 0.4 parts isopropyl cyanoacetate, and the diameter of the low-temperature expanding particles is 50 μm.

[0081] Example 24: This example differs from Example 13 in that the hydrophobic inner layer includes a first hydrophobic inner layer material and a second hydrophobic inner layer material with a mass ratio of 1:1. The first hydrophobic inner layer material is prepared according to the method of Example 1, and the second hydrophobic inner layer material is prepared according to the method of Example 13.

[0082] Example 25: This example differs from Example 24 in that the hydrophobic inner layer includes a first hydrophobic inner layer material and a second hydrophobic inner layer material with a mass ratio of 1:0.5.

[0083] Example 26: This example differs from Example 24 in that the hydrophobic inner layer includes a first hydrophobic inner layer material and a second hydrophobic inner layer material with a mass ratio of 1:1.5.

[0084] Example 27: The difference between this example and Example 2 is that the thickness of the scale-inhibiting outer layer material is 0.15 cm.

[0085] Example 28: The difference between this example and Example 2 is that the thickness of the scale-inhibiting outer layer material is 0.25 cm.

[0086] Example 29: This example differs from Example 2 in that it describes a method for preparing a composite hydrophobic material that inhibits crystallization in tunnel drainage pipes, comprising the following steps:

[0087] S1. First, coat the inner wall of the pipe with a second hydrophobic inner layer material with a thickness of 0.03cm. The coating method is to take any point corresponding to the center of the pipe as the center point, and then coat multiple paths outward from the center point, and the end point of the path returns to the center point. After coating, use a light dryer to dry and cure at 80°C for 8 minutes.

[0088] S2. After the second hydrophobic inner layer material has dried, coat the inner wall of the pipe with a first hydrophobic inner layer material with a thickness of 0.03cm in the blank area between the second hydrophobic inner layer material, and dry it in a hot air drying oven at 70℃ for 25 minutes to obtain the hydrophobic inner layer.

[0089] S3. Apply a scale-inhibiting outer layer with a thickness of 0.20cm to obtain the composite material.

[0090] Example 30: The difference between this example and Example 29 is that in step S1, the product is dried and cured at 75°C for 5 minutes using a light dryer.

[0091] Example 31: The difference between this example and Example 29 is that in step S1, the product is dried and cured at 85°C for 10 minutes using a light dryer.

[0092] Example 32: The difference between this example and Example 29 is that in step S2, the product is dried in a hot air drying oven at 65°C for 20 minutes.

[0093] Example 33: The difference between this example and Example 29 is that in step S2, the product is dried in a hot air drying oven at 75°C for 30 minutes.

[0094] Experimental Example: The description of this experimental example is based on the scheme described in Example 1 or 2, and aims to illustrate the practical application effect of the present invention.

[0095] Experimental Design 1: To investigate the performance of the hydrophobic inner layer and scale-inhibiting outer layer in Example 1, a 2cm thick HDPE pipe with a length of 15cm was selected. One-quarter of the pipe's cross-section was cut open (to facilitate observation of the internal crystallization effect), leaving three-quarters for simulation experiments. Both sides were sealed with silicone rubber (HG / T3947-2007 single-package room temperature curing silicone rubber) and tape. A 30-day immersion simulation was conducted at room temperature. The results are as follows:

[0096] 1. Investigate the effects of the component ratio of the hydrophobic inner layer and the scale-inhibiting outer layer, as well as the preparation parameters, on the performance of the monolayer.

[0097] Table 1. Anti-crystallization rate of the hydrophobic inner layer in Examples 1, 3-4, 9-10 and Comparative Example 1.

[0098] Group Example 1 Example 3 Example 4 Example 9 Example 10 Compare with Example 1 Anti-crystallization rate % 89.08 87.69 88.54 88.01 88.92 43.21

[0099] Table 2. Scale inhibition rates of the scale-inhibiting outer layer in Examples 1, 5-8, 11-12 and Comparative Example 1.

[0100]

[0101] The difference between Comparative Example 1 and Example 1 is that the inside of the pipe is not coated with any material;

[0102] A 30-day immersion simulation experiment showed that... Figure 1 (Compared to Example 1) The original pipe material showed obvious internal crystallization. Figure 2(The hydrophobic inner layer of Example 1) can effectively inhibit the formation of crystals on the pipe surface and exert stable hydrophobic properties, but there is a slight phenomenon of hydrophobic interface peeling. Figure 3 (Scale-inhibiting outer layer of Example 1) Part of the scale-inhibiting outer layer remains on the inner surface of the pipe, indicating that the scale-inhibiting outer layer has slow-release properties;

[0103] Furthermore, comparing Examples 1 and 3-12, it can be seen that too small or too large a proportion of tetrahydrofuran, too small or too large a stirring parameter during the preparation of the hydrophobic inner layer material A, too small or too large a proportion of the scale inhibitor solution, and too small a parameter for dissolving the colloidal material will all reduce the anti-crystallization and scale inhibition effect on the pipe. In Example 12, the scale inhibition rate is the same as that in Example 1, which has a higher temperature and longer stirring time. Therefore, from an economic point of view, the parameter effect of Example 1 is relatively better.

[0104] 2. Investigate the preparation method and composition of the hydrophobic inner layer and their effects on the anti-crystallization rate at low temperatures.

[0105] Table 3 shows the low-temperature (-10°C) anti-crystallization rate of the hydrophobic inner layer in Examples 13-23 and Comparative Examples 2-3.

[0106]

[0107] The difference between Comparative Example 2 and Example 13 is that there are no hydrophobic microspheres;

[0108] The difference between Comparative Example 3 and Example 13 is that the low-temperature expanded particles do not contain isopropyl cyanoacetate;

[0109] As shown in Table 3, although the low-temperature anti-crystallization rate of Control Example 2 (lacking hydrophobic microspheres) and Control Example 3 (lacking isopropyl cyanoacetate) was improved compared with Example 1, the improvement was much smaller than that of Examples 13-23. Therefore, both hydrophobic microspheres and isopropyl cyanoacetate played a certain role in preventing the material from crystallizing at low temperatures.

[0110] Comparing Examples 13-23, it can be seen that too small or too large a proportion of low-temperature expanding particles, too small or too large a proportion of hydrophobic microspheres, too small or too large a degree of solidification, too small or too large a size of hydrophobic microspheres, and too small or too large a proportion of expanded perlite in the low-temperature expanding particles will all reduce the improvement of the low-temperature anti-crystallization rate. Comparing Examples 13 and 24-26, it can be seen that the combination of the two can further improve the effect of the hydrophobic inner layer, and too small or too large a proportion of the second hydrophobic inner layer material will reduce the improvement of the effect. Therefore, in summary, the parameter effect of Example 26 is relatively better.

[0111] Experimental Design 2: The composite hydrophobic material was applied to the surface of a PE sheet according to the method in Example 2. Red ink was dotted onto the PE sheet surface with the inner layer already applied to reflect the effectiveness of the scale-inhibiting outer layer through color change. After drying in an oven, the scale-inhibiting outer layer was applied and then fixed in a simulated pipeline environment. A 30-day immersion simulation was conducted at room temperature. The results are as follows:

[0112] 3. Investigate the effects of the preparation steps and parameters of the composite material on the anti-crystallization rate of the composite material.

[0113] Table 4 shows the anti-crystallization rate of the composite materials in Examples 2, 27-33 and Comparative Examples 4-8.

[0114]

[0115] The difference between Comparative Example 4 and Example 29 is that in both steps S1 and S2, the first hydrophobic inner layer material is coated.

[0116] The difference between Comparative Example 5 and Example 29 is that the coating methods of the second hydrophobic inner layer material and the first hydrophobic inner layer material are reversed;

[0117] The difference between Comparative Example 6 and Example 29 is that in both steps S1 and S2, the second hydrophobic inner layer material is coated.

[0118] The difference between Comparative Example 7 and Example 2 is that in step S1, the material coated is a second hydrophobic inner layer.

[0119] The difference between Comparative Example 8 and Example 2 is that in step S1, the coating is a mixed hydrophobic inner layer material obtained by mixing the first hydrophobic inner layer material and the second hydrophobic inner layer material in a mass ratio of 1:1.

[0120] A 30-day immersion simulation experiment showed that... Figure 4 (Example 2) From left to right, the simulated conditions on day 10, day 20, and day 30 are shown. The degree of red ink color development reflects the efficacy of the outer layer, indicating that the scale-inhibiting outer layer can stably maintain a slow-release period of at least 30 days to prevent the formation of crystals. After the experiment, the scale-inhibiting outer layer on the surface of the PE sheet was removed and cleaned. It was observed that the hydrophobic inner layer did not experience any slight peeling and showed good hydrophobic properties.

[0121] Compared with the single-layer performance explored in Experimental Design 1, the anti-crystallization rate of the double-layer composite material is obviously improved. The scale inhibition rate is only slightly improved, and since Examples 27 to 33 are improvements on the hydrophobic inner layer structure, the scale inhibition rate is maintained between 94.76 and 95.03, and the fluctuation range is small, so they are not compared one by one.

[0122] As shown in Table 4, since the second hydrophobic inner layer material used in Comparative Example 4 is the same as the first hydrophobic inner layer material used in Example 1, that is, no improvement was made in Example 13, while the performance of the second hydrophobic inner layer material in Comparative Example 5 is better than that of the first hydrophobic inner layer material, and the umbrella rib is the key part that supports the entire hydrophobic inner layer, so the second hydrophobic inner layer material is better as the umbrella rib than the first hydrophobic inner layer material. Comparative Example 6 only uses the second hydrophobic inner layer material, and although its performance is worse than that of Comparative Example 4, it is not as good as the combination of the two. Therefore, Comparative Examples 4 to 6 significantly reduced the improvement of the anti-crystallization rate compared with Examples 27 to 30.

[0123] Since the second hydrophobic inner layer material is an improvement on the first hydrophobic inner layer material, the material properties of Comparative Examples 6 and 7 are improved compared to Example 2, but the effect is weaker than that of the coating method in Example 29.

[0124] Comparing Examples 27-33, it can be seen that too small a thickness of the scale-inhibiting outer layer, too low drying and curing parameters, and too low hot air drying parameters will reduce the improvement of the anti-crystallization rate. When the scale-inhibiting outer layer is larger, the protection strength of the hydrophobic inner layer is higher, so the anti-crystallization rate is higher than that of Example 1. Although the anti-crystallization rate is higher than that of Example 29 when the drying and curing and hot air drying parameters are higher, the improvement is smaller. Therefore, from an economic point of view, the steps and parameters of Example 29 are relatively better.

[0125] In summary, experimental designs 1 and 2 demonstrate that the material has excellent hydrophobicity and scale inhibition properties. Furthermore, the scale-inhibiting outer layer can prevent slight detachment of the hydrophobic inner layer. In long-distance water transport, this composite hydrophobic material can maintain its scale inhibition performance for at least 30 days, and the hydrophobic inner layer can maintain its hydrophobic performance for a long time without external abrasion.

Claims

1. A composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes, characterized in that, This includes a hydrophobic inner layer for coating the inner wall of pipes and a scale-inhibiting outer layer that adheres to the outer surface of the hydrophobic inner layer. The hydrophobic inner layer comprises, by mass ratio, 4.5~5.5:6:0.05:1:1:0.02 tetrahydrofuran: solvent volatiles: surfactant: nano silica: crosslinking agent: curing agent; wherein the surfactant is a silane coupling agent, the solvent volatiles are isopropanol, the crosslinking agent is RTV-2 silicone rubber, and the curing agent is DOP; The scale-inhibiting outer layer comprises, by mass ratio: a scale inhibitor solution and a colloidal material in a ratio of 1 to 1.5:5, wherein the scale inhibitor solution comprises, by mass ratio: EDTA: hydrolyzed maleic anhydride: aminosulfonic acid in a ratio of 4:3:0.5 to 0.6; and the colloidal material comprises, by mass ratio: polyvinyl alcohol: sodium alginate in a ratio of 1:0.

1.

2. The composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes as described in claim 1, characterized in that, The preparation method of the hydrophobic inner layer material is as follows: at room temperature, tetrahydrofuran and solvent volatile agent are first mixed to obtain solution A, then nano-silica and surfactant are added to solution A in sequence and stirred for 4-6 min to obtain solution B, then crosslinking agent and curing agent are added to solution B in sequence and stirred for 9-11 min to obtain hydrophobic inner layer material.

3. The composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes as described in claim 1, characterized in that, The preparation method of the scale inhibitor outer layer is as follows: first, the raw materials of the scale inhibitor solution are mixed in proportion to obtain the scale inhibitor solution, then the colloidal material is added into the scale inhibitor solution in proportion, and then dissolved and stirred in a water bath at 92~98℃ for 0.4~0.6h. After the dissolution and stirring are completed, the scale inhibitor outer layer material is obtained.

4. The method for preparing a composite hydrophobic material for inhibiting crystallization in tunnel drainage pipes as described in claim 1, characterized in that, Includes the following steps: S1. First, coat the inner wall of the pipe with a hydrophobic inner layer material with a thickness of ≤0.03cm; S2. The hydrophobic inner layer material is dried to obtain the hydrophobic inner layer. S3. Then, coat the outer surface of the hydrophobic inner layer with a scale-inhibiting outer layer material with a thickness of 0.15~0.25cm, and dry it to obtain the composite material.

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