A yttrium-doped zinc oxide water pipe inner wall anticorrosive elastic thermal insulation coating, a preparation method and application thereof

Abstract

This application relates to the field of membrane materials, and more particularly to a yttrium-doped zinc oxide anti-corrosion and heat-insulating coating for the inner wall of water pipes, its preparation method, and its application. The coating, by weight, comprises the following raw materials: 30-40 parts of base emulsion, 10-15 parts of yttrium-doped zinc oxide, 5-10 parts of silicone oil, 5-10 parts of polysiloxane elastomer microspheres, 5-10 parts of binder, 15-20 parts of inorganic compound, 5-10 parts of hydrophobic aerogel, 2-5 parts of nano-silver, 3-5 parts of nano-ATO, 5-10 parts of nano-zirconia, 10-15 parts of functional additives, 10-15 parts of diluent, 1-3 parts of leveling agent, 2-5 parts of wetting agent, and 1-3 parts of dispersant; wherein the base emulsion is an organosilicon-modified polyurethane emulsion. The preparation method includes mixing, stirring, coating, and curing steps. When the coating thickness obtained in this application is 5~20mm, the thermal conductivity can be as low as 0.035~0.05 W / (m·K), the hydrophobic angle is ≥120°, the hydrophobicity is ≥98%, and it can withstand water immersion for more than 360 days without peeling or bubbling. It achieves the three functions of heat preservation, hydrophobic anti-condensation and anti-corrosion of water pipe inner wall. The ultra-thin coating does not reduce the diameter and does not affect the water flow area of ​​the water pipe.

Description

Technical Field

[0001] This application relates to the field of thermal insulation materials technology, and in particular to a yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, its preparation method and application, which is suitable for the inner wall insulation, anti-condensation, anti-corrosion and antibacterial treatment of various cold and hot water pipes, drinking water pipes and HVAC pipes, and can also be adapted to the inner wall treatment needs of various pipes such as industrial steam transmission pipes and air conditioning chilled water pipes. Background Technology

[0002] Currently, water pipe insulation mainly adopts external wall insulation, with commonly used materials such as rock wool, polyurethane foam, and glass wool. However, this method has the following drawbacks: 1. The external wall insulation layer is thick, occupying a lot of space, making construction difficult, especially in confined spaces (such as ceilings or inside walls); 2. Even after external wall insulation of cold water pipes, condensation easily forms on the inner wall. Long-term condensation can lead to corrosion, scaling, and microbial growth on the inner wall, affecting water quality and pipe lifespan; 3. Traditional external wall insulation construction is complex, requiring pipe dismantling, wrapping, and fixing, resulting in low construction efficiency. Furthermore, the cost of dismantling old pipes during renovation is high and affects normal use; 4. Some insulation materials are unsuitable for use around drinking water pipes, posing environmental and safety hazards.

[0003] Currently, a few internal wall insulation coatings use pure polyurethane or pure silicone systems. Pure polyurethane has poor water resistance and is prone to peeling off after long-term immersion, while pure silicone has weak adhesion and insufficient mechanical strength. Moreover, most coatings do not take into account antibacterial and anti-condensation functions, and cannot meet the hygiene and safety requirements of drinking water pipes. Therefore, developing an ultra-thin, high-efficiency, hydrophobic, anti-corrosion, antibacterial, and easy-to-apply water pipe internal wall insulation coating has become an urgent technical problem to be solved. Summary of the Invention

[0004] To address the aforementioned problems, the first aspect of this application provides a yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, comprising, by weight, the following raw materials: 30-40 parts base emulsion, 10-15 parts yttrium-doped zinc oxide, 5-10 parts silicone oil, 5-10 parts polysiloxane elastomer microspheres, 5-10 parts adhesive, 15-20 parts inorganic compound, 5-10 parts hydrophobic aerogel, 2-5 parts nano silver, 3-5 parts nano ATO, 5-10 parts nano zirconium oxide, 10-15 parts functional additives, 10-15 parts diluent, 1-3 parts leveling agent, 2-5 parts wetting agent, and 1-3 parts dispersant.

[0005] As a preferred embodiment, the mass ratio of the base emulsion to the functional additive is (30~40):(10~15).

[0006] As a preferred embodiment, the mass ratio of yttrium oxide to zinc oxide in the yttrium-doped zinc oxide is (8~10):(5~8).

[0007] As a preferred embodiment, the inorganic compound is perlite powder, diatomaceous earth, expanded vermiculite, ceramic fiber, and glass microspheres, with a mass ratio of (4~5):(5~6):(4~5):(3~4):(2~3).

[0008] As a preferred embodiment, the functional additive is a composition of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether and methyltriethoxysilane, wherein the mass ratio of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether and methyltriethoxysilane is (2~3):(3~3.5):(1~2):(4~5).

[0009] As a preferred embodiment, the mass ratio of the base emulsion, diluent, and silicone oil is (30~40):(10~15):(5~10).

[0010] As a preferred embodiment, the mass ratio of the base emulsion, diluent, and hydrophobic aerogel is (30~40):(10~15):(5~10).

[0011] As a preferred embodiment, the base emulsion is an organosilicon-modified polyurethane emulsion, which serves as the film-forming base material.

[0012] As a preferred embodiment, the diluent is a mixed solvent of propylene glycol methyl ether acetate and isopropanol, with a mass ratio of propylene glycol methyl ether acetate to isopropanol of (1~1.5):(4~4.5); at least one of ethanol, methanol, isopropanol or ethyl acetate may also be used, with ethanol or isopropanol being preferred.

[0013] As a preferred embodiment, the hydrophobic aerogel is a composition of silica aerogel and alumina, wherein the mass ratio of silica aerogel to alumina is (2.5~5):(2.5~5).

[0014] This application incorporates yttrium-doped zinc oxide, which possesses excellent synergistic properties of high-temperature resistance and antibacterial activity. The introduction of rare-earth yttrium oxide effectively inhibits high-temperature grain coarsening of zinc oxide, improves material density and structural stability, making it less prone to softening, decomposition, or phase transformation under high-temperature environments, thus enhancing the system's heat resistance and thermal stability. Simultaneously, doping modification optimizes material surface activity, promotes the effective action of antibacterial ions, and exhibits good inhibitory and bactericidal effects against various common bacteria, providing long-lasting and stable antibacterial performance. The yttrium-doped zinc oxide dopant combines high-temperature resistance, structural enhancement, and antibacterial properties, exhibiting good compatibility and strong aging resistance. As the main functional filler in this patent, it is used for the high-temperature antibacterial effect of the coating, improving the coating's service life and safety in complex environments.

[0015] The combination of silicone oil, adhesive, inorganic compound, hydrophobic aerogel and other materials in this application can maintain excellent thermal insulation, heat insulation, elasticity and stretching, corrosion resistance and mechanical properties, while also maintaining good anti-corrosion, antibacterial, antifouling, waterproof, salt resistance and aging resistance properties; the organosilicon-modified polyurethane emulsion as a film-forming base material can effectively improve the aging resistance of the coating.

[0016] As a preferred embodiment, the functional additive is a composition of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether and methyltriethoxysilane, in a mass ratio of (2~3):(3~3.5):(1~2):(4~5); more preferably, the mass ratio of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether and methyltriethoxysilane is (4.2~4.5):(3.2~3.3):(1.2~1.5):(4~5).

[0017] The aforementioned compound functional additives added in this application can effectively assist in improving the mechanical properties of the membrane and effectively ensure the waterproof and aging corrosion resistance of the self-cleaning membrane. Specifically, epoxy block polyether and polyethylene glycol methyl ether can enhance the molecular network construction effect of the functional additives in the membrane material through the intercalation of different molecular chain lengths, thereby improving the compactness of the internal three-dimensional network of the membrane. Molecular chains of different lengths easily form mutual entanglement, which helps to improve intermolecular forces, thus assisting in improving the mechanical properties of the membrane. The addition of arylphenol polyoxyethylene ether can effectively reduce the aggregation of nanoparticles, allowing the nanoparticles to be more uniformly distributed in the membrane layer using epoxy block polyether and polyethylene glycol methyl ether as dispersion carriers. This avoids the formation of large micropores due to particle aggregation, which would affect the connection between molecules and particles, thereby reducing the tribomechanical properties of the membrane. Methyltriethoxysilane can reduce the aggregation of materials such as silicone oil and hydrophobic aerogels, improve the dispersibility, wettability, and adhesion of materials in organic matrices, reduce coating peeling and flaking, and improve the corrosion resistance and weather resistance of the coating, thereby improving the tensile strength, impact strength, and heat resistance of the material. On the other hand, the compounded functional additives can also help form a smooth film layer, thereby achieving comprehensive properties of the film layer such as thermal conductivity, self-cleaning, waterproofing, oil resistance, salt resistance, corrosion resistance, and aging resistance.

[0018] As a preferred embodiment, the leveling agent is at least one of silicone leveling agents, preferably silicone leveling agent BYK-306.

[0019] As a preferred embodiment, the wetting agent is at least one of nonionic wetting agents.

[0020] As a preferred embodiment, the dispersant is at least one of acrylic acid and betaine, preferably acrylic acid, and more preferably acrylic acid BYK-163.

[0021] The second aspect of this application provides a method for preparing the aforementioned yttrium-doped zinc oxide anti-corrosion and elastic thermal insulation coating for the inner wall of water pipes, the specific steps of which are as follows:

[0022] S1: Add the diluent, functional additives, and base emulsion to a high-speed mixer and stir at 1200~1800 r / min for 10~20 min until homogeneous;

[0023] S2: After adding silicone oil and polysiloxane elastomer microspheres, continue stirring at a speed of 1200~1800 r / min for 15~25 min;

[0024] S3: After adding the hydrophobic aerogel, continue stirring at 1200~1800 r / min for 15~25 min;

[0025] S4: After adding the inorganic compound, continue stirring at 1200~1800 r / min for 15~25 min;

[0026] S5: After adding binder, nano silver, nano ATO, nano zirconium oxide, and yttrium oxide-doped zinc oxide, continue stirring at 1200~1800 r / min for 15~25 min;

[0027] S6: Finally, add leveling agent, wetting agent and dispersant, and stir at 800~1000 r / min for 8~10 min to obtain coating mixture;

[0028] S7: Spray, dip, or brush the coating mixture onto the inner wall surface of the water pipe and heat it to 60~80℃ for 3~4 hours to cure; or let it air dry at room temperature for 24 hours to obtain the yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic heat insulation coating.

[0029] This application, through the synergistic effect of "organosilicon-modified polyurethane emulsion + compound functional additives + multi-element nanofillers," solves the technical problems of existing water pipe inner wall coatings, namely "poor thermal insulation, weak water resistance, easy cracking, and single function." It achieves a four-in-one function of thermal insulation, corrosion prevention, anti-condensation, and antibacterial properties, and is easy to apply, ultra-thin without diameter reduction. It meets the diverse performance requirements of steam and high-temperature pipelines (industrial steam transmission pipes, boiler flues and connecting pipes, high-temperature process medium transmission pipes (temperature > 50℃)), hot water pipelines (domestic hot water supply and return pipes, centralized heating supply and return pipes, solar hot water pipes, underfloor heating pipes), low-temperature and refrigeration pipelines (air conditioning chilled water pipes, chiller unit connecting pipes, cold storage refrigeration pipes, compressed air pipelines (anti-condensation)), and pipelines in special environments, including thermal insulation, elastic expansion, water resistance, corrosion resistance, seepage prevention, and salt resistance. This coating achieves excellent comprehensive performance, extends the service life of water pipes, improves safety performance, reduces operating costs, is easy to apply, and has significant economic benefits, demonstrating excellent application prospects.

[0030] The mechanism and advantages of this application

[0031] 1. Wide temperature range weather resistance: Stable operation from -60℃ to 250℃

[0032] Mechanism: Using a matrix of yttrium-doped zinc oxide, silicone oil, and hydrophobic aerogel, the main chain of the system is composed of Si-O bonds with a bond energy of approximately 452 kJ / mol, significantly higher than that of C-C bonds (347 kJ / mol), endowing the material with excellent thermal stability. The introduction of phenyl substituents into the molecular chain disrupts chain segment regularity and reduces crystallinity, preventing brittle fracture caused by crystallization at low temperatures. After appropriate cross-linking to form a three-dimensional network structure, the material does not melt or flow at high temperatures, and remains flexible and elastic at low temperatures, without hardening or brittle fracture, exhibiting stable mechanical properties over a wide temperature range.

[0033] Advantages: It is suitable for extreme environments and can be used in industrial pipelines (high-temperature steam pipes, low-temperature refrigerant pipes), solving the pain points of traditional coatings such as "softening at high temperatures and cracking at low temperatures"; it has excellent long-term stability, working stably at -60℃ to 250℃, consistent with performance data and material characteristics; after 1000 hours of continuous operation, the elastic recovery rate is ≥90%, the thermal insulation performance decay is ≤5%, and there is no powdering or peeling.

[0034] 2. Flexible self-healing: Adapts to substrate deformation, preventing coating cracking.

[0035] Mechanism: The silicone oil and hydrophobic aerogel composite matrix exhibits excellent elasticity, with an elongation at break ≥300% and a Shore hardness of A20~40. The cross-linked network of the system contains reversible physical interactions such as hydrogen bonds and van der Waals forces, allowing for rapid rebound under tensile stress or thermal expansion and contraction of the substrate, demonstrating good dimensional stability. Some formulations incorporate polysiloxane elastomer microspheres, which release active components upon the formation of microcracks to achieve interfacial reconstruction, enabling the material to possess self-healing capabilities for microcracks with a repair efficiency ≥80%.

[0036] Advantages include: compatibility with flexible / deformable substrates, suitable for flexible pipes, expansion joints, rubber seals, and curved equipment, solving the problem of "substrate deformation leading to coating peeling and insulation failure" in traditional rigid insulation materials (such as rock wool and polyurethane); impact and vibration resistance, the coating does not crack or peel after industrial equipment vibration (such as pumps and fans) or external impact (such as construction collisions), ensuring the continuity of insulation and protection.

[0037] 3. Superhydrophobic protection: water-resistant, antifouling, and corrosion-resistant.

[0038] Mechanism: By adding hydrophobic aerogel, a "micro-nano rough structure + low surface energy coating" is constructed, with a surface contact angle ≥120° and a hydrophobicity ≥98%, achieving the "lotus leaf effect" and thus achieving excellent hydrophobic and anti-condensation effects.

[0039] Advantages include: excellent water resistance, preventing water from penetrating or wetting the coating surface when it comes into contact with the pipe, thus avoiding moisture intrusion into the insulation layer (traditional insulation materials double their thermal conductivity after absorbing water, leading to insulation failure); stain resistance and easy cleaning, making it difficult for dust and oil to adhere, and rainwater can easily clean it, maintaining the coating's appearance and insulation performance (especially suitable for outdoor equipment and pipes connected to building exterior walls); strong corrosion resistance, isolating moisture, salt spray, and weak acids and alkalis (such as industrial exhaust gases and marine atmospheres), protecting the substrate (metal, concrete, plastic) from rusting and aging, and extending the service life of the equipment.

[0040] 4. High-efficiency thermal insulation: low thermal conductivity, energy saving and consumption reduction

[0041] Mechanism: The matrix of yttrium-doped zinc oxide, silicone oil, and hydrophobic aerogel has a low thermal conductivity of 0.1~0.15 W / (m·K); the system is further enhanced with high-efficiency thermal insulation fillers such as hollow glass microspheres, aerogel, and ceramic fibers, resulting in a thermal conductivity as low as ≤0.03 W / (m·K). The material ultimately forms a continuous elastic matrix with a closed pore structure, which effectively hinders solid-phase heat conduction and air convection, achieving excellent thermal insulation performance.

[0042] Advantages include: high thermal insulation efficiency; with a coating thickness of 5-20 mm, the thermal conductivity can be as low as 0.035-0.05 W / (m·K), close to that of polyurethane foam (0.025-0.035 W / (m·K)), but with the advantages of elasticity and resistance to high and low temperatures; significant energy saving and consumption reduction; when used in industrial pipelines (such as steam pipes and refrigeration pipes), it can reduce heat loss / cold loss. According to calculations, compared with traditional rock wool insulation + iron sheet protection, the energy saving rate is increased by 15%-25%; thin coating is highly efficient; compared with traditional insulation materials (requiring a thickness of 50-100 mm), the coating thickness is only 1 / 3 to 1 / 5 of that, saving space, especially suitable for narrow spaces and complex shaped equipment (such as valves, flanges, and irregularly shaped pipes). Detailed Implementation

[0043] The following will further illustrate and demonstrate the technical solutions described above in this application through specific implementation schemes. The following embodiments are merely practical examples used to illustrate and explain the content of the technical solutions in the specification, and should not limit the scope of the claims to be protected by this application. All technical products based on the technical solutions described in this application should be covered within the scope of protection of this application.

[0044] In the following embodiments, unless otherwise specified, the raw materials are all commercially available products or can be prepared by methods known to those skilled in the art.

[0045] Example 1

[0046] The first aspect of this embodiment provides a yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, the raw materials of which, by weight, are: 35 parts base emulsion, 12 parts yttrium-doped zinc oxide, 8 parts silicone oil, 8 parts polysiloxane elastomer microspheres, 8 parts binder, 18 parts inorganic compound, 8 parts hydrophobic aerogel, 3 parts nano silver, 4 parts nano ATO, 7 parts nano zirconium oxide, 13 parts functional additives, 12 parts diluent, 2 parts leveling agent, 3 parts wetting agent, and 2 parts dispersant.

[0047] As a preferred embodiment, the base emulsion is a silicone-modified polyurethane emulsion as the film-forming base material; the binder is a styrene-acrylate type; the inorganic compounds are perlite powder, diatomaceous earth, expanded vermiculite, ceramic fiber, and glass microspheres in a mass ratio of 4:5:4:3:2; the hydrophobic aerogel is a composition of silica aerogel and alumina in a mass ratio of 3:3; the functional additives are a composition of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether, and methyltriethoxysilane in a mass ratio of 2.5:3.2:1.5:4.8; the diluent is 95wt% ethanol; the leveling agent is silicone leveling agent BYK-306; the wetting agent is a nonionic wetting agent; and the dispersant is acrylic BYK-163.

[0048] The second aspect of this embodiment provides a method for preparing the above-mentioned yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, the specific steps of which include:

[0049] S1: Add the diluent, functional additives, and base emulsion to a high-speed mixer and stir at 1500 r / min for 15 min until homogeneous;

[0050] S2: After adding silicone oil and polysiloxane elastomer microspheres, continue stirring at 1500 r / min for 20 min.

[0051] S3: After adding the hydrophobic aerogel, continue stirring at 1500 r / min for 20 min;

[0052] S4: After adding the inorganic compound, continue stirring at 1500 r / min for 20 min;

[0053] S5: After adding the binder, nano silver, nano ATO, nano zirconium oxide, and yttrium-doped zinc oxide, continue stirring at 1500 r / min for 20 min;

[0054] S6: Finally, add the leveling agent, wetting agent and dispersant, and stir at 1000 r / min for 10 min to obtain the coating mixture;

[0055] S7: Spray the coating mixture onto the inner wall of a DN100 galvanized steel pipe, heat to 80℃ and cure for 3 hours to obtain a yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic heat insulation coating.

[0056] Example 2

[0057] The first aspect of this embodiment provides a yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, the raw materials of which, by weight, are: 38 parts of base emulsion, 12 parts of yttrium-doped zinc oxide, 9 parts of silicone oil, 9 parts of polysiloxane elastomer microspheres, 9 parts of binder, 19 parts of inorganic compound, 9 parts of hydrophobic aerogel, 4 parts of nano silver, 4 parts of nano ATO, 8 parts of nano zirconium oxide, 14 parts of functional additives, 14 parts of diluent, 2 parts of leveling agent, 4 parts of wetting agent, and 2 parts of dispersant.

[0058] As a preferred embodiment, the base emulsion is a silicone-modified polyurethane emulsion as the film-forming base material; the binder is a styrene-acrylate type; the inorganic compounds are perlite powder, diatomaceous earth, expanded vermiculite, ceramic fiber, and glass microspheres in a mass ratio of 4.5:5.5:4.5:3.5:2.5; the hydrophobic aerogel is a composition of silica aerogel and alumina in a mass ratio of 4:4; the functional additives are a composition of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether, and methyltriethoxysilane in a mass ratio of 4.3:3.2:1.3:4.5; the diluent is a mixed solvent of propylene glycol methyl ether acetate and isopropanol in a mass ratio of 1.2:4.2; the leveling agent is silicone leveling agent BYK-306; the wetting agent is a nonionic wetting agent; and the dispersant is acrylic BYK-163.

[0059] The second aspect of this embodiment provides a method for preparing the above-mentioned yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, the specific steps of which include:

[0060] S1: Add the diluent, functional additives, and base emulsion to a high-speed mixer and stir at 1600 r / min for 18 min until homogeneous;

[0061] S2: After adding silicone oil and polysiloxane elastomer microspheres, continue stirring at 1600 r / min for 22 min.

[0062] S3: After adding the hydrophobic aerogel, continue stirring at 1600 r / min for 22 min;

[0063] S4: After adding the inorganic compound, continue stirring at 1600 r / min for 22 min;

[0064] S5: After adding the binder, nano silver, nano ATO, nano zirconium oxide, and yttrium-doped zinc oxide, continue stirring at 1600 r / min for 22 min.

[0065] S6: Finally, add leveling agent, wetting agent and dispersant, and stir at 900 r / min for 9 min to obtain coating mixture;

[0066] S7: Apply the coating mixture to the inner wall of the PPR water pipe and allow it to air dry and cure at room temperature for 24 hours to obtain the yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic heat insulation coating.

[0067] Comparative Example 1

[0068] The specific implementation method of this comparative example is basically the same as that of Example 1, except that "hydrophobic aerogel" is deleted. The rest is the same as that of Example 1, and it is used to verify the effect of hydrophobic aerogel on thermal insulation and hydrophobic performance.

[0069] A yttrium-doped zinc oxide anti-corrosion and heat-insulating coating for the inner wall of water pipes, by weight, comprises the following raw materials: 35 parts base emulsion, 12 parts yttrium-doped zinc oxide, 8 parts silicone oil, 8 parts polysiloxane elastomer microspheres, 8 parts binder, 18 parts inorganic compound, 3 parts nano silver, 4 parts nano ATO, 7 parts nano zirconium oxide, 13 parts functional additives, 12 parts diluent, 2 parts leveling agent, 3 parts wetting agent, and 2 parts dispersant; the preparation method is the same as in Example 1.

[0070] Comparative Example 2

[0071] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the "base emulsion" is replaced with "pure polyurethane emulsion". The rest is the same as that of Example 1, which is used to verify the necessity of organosilicon modification.

[0072] A yttrium-doped zinc oxide anti-corrosion and heat-insulating coating for the inner wall of water pipes, by weight, comprises the following raw materials: 35 parts pure polyurethane emulsion, 12 parts yttrium-doped zinc oxide, 8 parts silicone oil, 8 parts polysiloxane elastomer microspheres, 8 parts adhesive, 18 parts inorganic compound, 8 parts hydrophobic aerogel, 3 parts nano silver, 4 parts nano ATO, 7 parts nano zirconium oxide, 13 parts functional additives, 12 parts diluent, 2 parts leveling agent, 3 parts wetting agent, and 2 parts dispersant; the preparation method is the same as in Example 1.

[0073] Comparative Example 3

[0074] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the "functional additive" is replaced with a single polyethylene glycol methyl ether. The rest is the same as that of Example 1, which is used to verify the necessity of compound functional additives.

[0075] A yttrium-doped zinc oxide anti-corrosion and heat-insulating coating for the inner wall of water pipes, by weight, comprises the following raw materials: 35 parts base emulsion, 12 parts yttrium-doped zinc oxide, 8 parts silicone oil, 8 parts polysiloxane elastomer microspheres, 8 parts binder, 18 parts inorganic compound, 8 parts hydrophobic aerogel, 3 parts nano silver, 4 parts nano ATO, 7 parts nano zirconium oxide, 13 parts ethylene glycol methyl ether, 12 parts diluent, 2 parts leveling agent, 3 parts wetting agent, and 2 parts dispersant; the preparation method is the same as in Example 1.

[0076] Comparative Example 4

[0077] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the mass ratio of inorganic compounds is adjusted to 4:6:5:4:3. The rest is the same as that of Example 1, and it is used to verify the rationality of the inorganic compound ratio.

[0078] A yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, the raw materials are the same as those in Example 1 by mass parts; wherein, the inorganic compounds are perlite powder, diatomaceous earth, expanded vermiculite, ceramic fiber and glass microspheres, and their mass ratio is 4:6:5:4:3; the preparation method is the same as that in Example 1.

[0079] Comparative Example 5

[0080] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the mass ratio of the functional additives is adjusted to 3:3.5:2:5. The rest is the same as that of Example 1, and it is used to verify the rationality of the functional additive ratio.

[0081] A yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating, the raw materials are the same as those in Example 1 by weight; wherein, the functional additive is a composition of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether and methyltriethoxysilane, with a mass ratio of 3:3.5:2:5; the preparation method is the same as that in Example 1.

[0082] Performance Evaluation

[0083] 1. Thermal insulation performance (core energy saving)

[0084] Evaluation indicators: thermal conductivity, heat preservation efficiency

[0085] Test standards: GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Protective Hot Plate Method" and GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Heat Flow Meter Method"

[0086] Test method:

[0087] Thermal conductivity: The steady-state thermal conductivity (W / (m·K)) of the coating (thickness 5~10mm) was tested using a protective hot plate apparatus at 25℃ and an average temperature of 50℃.

[0088] Thermal insulation efficiency: Simulating an industrial pipeline scenario (substrate temperature 150℃, ambient temperature 25℃), the temperature drop or heat loss rate of the substrate surface after coating (10mm thickness) was measured, and the thermal insulation efficiency was calculated by comparing it with the uncoated sample.

[0089] Criteria for judgment:

[0090] Thermal conductivity ≤ 0.05 W / (m·K) (for a thickness of 10 mm, the closer to 0.035 W / (m·K) the better);

[0091] Thermal insulation efficiency ≥85% (compared to the uncoated sample, heat loss is reduced by ≥85%).

[0092] 2. Superhydrophobic properties (protective core)

[0093] Evaluation indicators: static contact angle, self-cleaning property, hydrophobic durability (after UV aging and friction).

[0094] Test standards: GB / T 30693-2014 "Determination of contact angle of plastic films and sheets", ISO 19403-2:2017 "Determination of hydrophobic properties of paints and varnishes - Part 2: Roll-off angle"

[0095] Test method:

[0096] Static contact angle: Using a contact angle measuring instrument, 5 μL of deionized water was added to the coating surface, and the contact angle (θ) was recorded.

[0097] Self-cleaning property: The dust adhesion rate on the coating surface was tested according to Appendix A of GB / T 30693-2014. The lower the value, the better the self-cleaning property.

[0098] Hydrophobic durability: ① Contact angle was tested after UV aging (xenon lamp aging for 1000 hours, simulating outdoor exposure); ② Contact angle was tested after Martindale abrasion test (load 500g, 1000 cycles).

[0099] Criteria for judgment:

[0100] Initial static contact angle ≥120°, self-cleaning performance ≤12%;

[0101] After UV aging, the contact angle is ≥110°, and after friction, the contact angle is ≥105°, with no obvious hydrophilicity.

[0102] 3. High and low temperature resistance (wide temperature range adaptable core)

[0103] Evaluation indicators: high and low temperature cycling stability, high temperature aging stability

[0104] Test standards: GB / T 1735-2009 "Determination of heat resistance of paints and varnishes", GB / T 15256-2014 "Determination of low-temperature brittleness of vulcanized rubber or thermoplastic rubber - Single sample method"

[0105] Test method:

[0106] High and low temperature cycling: The coated sample was placed in a high and low temperature test chamber and subjected to a cycle test of -60℃ (4h) → room temperature (2h) → 150℃ (4h) → room temperature (2h) for a total of 100 cycles. After the test, the coating adhesion retention rate was tested.

[0107] High temperature aging: The coating was placed at a constant temperature of 150℃ for 1000 hours, and the tensile strength retention rate of the coating was tested.

[0108] Criteria for judgment:

[0109] After high and low temperature cycling: the coating showed no cracking or peeling, and the adhesion retention rate was ≥90%;

[0110] After high-temperature aging: tensile strength retention rate ≥80%, no powdering or flowing.

[0111] 4. Elastic self-healing performance (adapts to deformed core)

[0112] Evaluation indicators: elastic recovery rate, microcrack self-healing efficiency

[0113] Test standards: Refer to GB / T 7759-2015 "Determination of Compression Set of Vulcanized Rubber or Thermoplastic Rubber" and ASTM D624-2016 "Tear Strength of Rubber and Elastomers - Test Method".

[0114] Test method:

[0115] Elastic recovery rate: Stretch the sample to 50% elongation, hold for 30 minutes, release, let stand for 1 hour, measure the recovered length, and calculate the recovery rate = (length before stretching - length after recovery) / (length before stretching × 50%) × 100%;

[0116] Microcrack self-healing: Use a blade to make microcracks 0.5mm deep and 5mm long on the coating surface, place it in an environment of 80℃ and 60% humidity for 24 hours, observe the crack closure under a microscope, and calculate the repair efficiency = (initial crack width - repaired crack width) / initial crack width × 100%.

[0117] Criteria for judgment:

[0118] Elastic recovery rate ≥90% (after 50% stretching);

[0119] Microcrack self-healing efficiency ≥80% (within 24 hours).

[0120] Performance test results

[0121] Group Thermal conductivity (W / (m·K)) Thermal insulation efficiency Self-cleaning property (%) Water contact angle (°) High and low temperature cycling stability High temperature aging stability Elastic recovery rate Microcrack self-healing efficiency Example 1 0.034 0.863 9.4 129.4 0.905 0.91 0.96 0.86 Example 2 0.036 0.852 10.2 126.5 0.908 0.903 0.955 0.853 Comparative Example 1 0.058 0.81 13.2 122.6 0.86 0.84 0.93 0.81 Comparative Example 2 0.064 0.79 12.1 124.8 0.83 0.846 0.86 0.83 Comparative Example 3 0.0526 0.83 12.5 102.8 0.825 0.84 0.877 0.82 Comparative Example 4 0.061 0.80 17.7 99.4 0.811 0.842 0.89 0.85 Comparative Example 5 0.051 0.832 18.5 98.6 0.80 0.832 0.865 0.846

[0122] From the data results of the embodiments and comparative examples of this application, as well as the tables above, it can be seen that Embodiments 1 and 2 of this application have significant advantages over Comparative Examples 1-5 in terms of thermal conductivity, insulation efficiency, self-cleaning property (%), waterproof-water contact angle (°), high and low temperature cycling stability, high temperature aging stability, elastic recovery rate, and microcrack self-repair efficiency. This is mainly due to the combined effect of the functional additives, inorganic materials, and other complementary technical solutions specified in this application. Comparative Examples 1-5, however, did not adopt the technical solutions specified in this application, resulting in significant disadvantages in the aforementioned performance tests. This further proves the necessity of the technical solutions specified in this application for achieving the technical effects of this application and solving the technical problems.

Claims

1. A yttrium-doped zinc oxide anti-corrosion and heat-insulating coating for the inner wall of water pipes, characterized in that: By weight, the raw materials are: 30-40 parts base emulsion, 10-15 parts yttrium-doped zinc oxide, 5-10 parts silicone oil, 5-10 parts polysiloxane elastomer microspheres, 5-10 parts binder, 15-20 parts inorganic compound, 5-10 parts hydrophobic aerogel, 2-5 parts nano silver, 3-5 parts nano ATO, 5-10 parts nano zirconium oxide, 10-15 parts functional additives, 10-15 parts diluent, 1-3 parts leveling agent, 2-5 parts wetting agent, and 1-3 parts dispersant. The base emulsion is a silicone-modified polyurethane emulsion; Preparation method of silicone-modified polyurethane emulsion (1) Take water-based polyurethane emulsion and place it in a high-speed mixer and stir at room temperature (800~1000r / min); (2) Slowly add silicone resin, the amount of which is 5%~10% of the mass of polyurethane emulsion, and at the same time add compatibilizer (the amount of which is 1%~2% of the total mass of the system); (3) Continue stirring for 40~60min, during which a small amount of polyether-modified siloxane can be added to improve the dispersibility of the system, avoid silicone agglomeration, and ensure that the emulsion is uniform and free of sediment; (4) Adjust the emulsion viscosity to 20~30s (Ford-4 cup) to adapt to the construction of the inner wall of water pipe, and obtain silicone-modified polyurethane emulsion. The adhesive is a styrene-acrylate type; The inorganic compound is a mixture of perlite powder, diatomaceous earth, expanded vermiculite, ceramic fiber, and glass microspheres in a mass ratio of (4~5):(5~6):(4~6):(3~4):(2~3). The hydrophobic aerogel is a silicon-based aerogel; The functional additive is a composition of polyethylene glycol methyl ether, epoxy block polyether, arylphenol polyoxyethylene ether and methyltriethoxysilane, in a mass ratio of (2~3):(3~3.5):(1~2):(4~5).

2. The yttrium oxide-doped zinc oxide anti-corrosion and heat-insulating coating for the inner wall of water pipes according to claim 1, characterized in that: The mass ratio of the base emulsion to the silicone oil is (30~40):(5~10).

3. The yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating according to claim 1, characterized in that: The nano-silver has a particle size of 50 nanometers.

4. The yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating according to claim 1, characterized in that: The particle size of the nano-ATO is 50 nanometers.

5. The yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating according to claim 1, characterized in that: The nano-zirconia has a particle size of 50 nanometers.

6. The yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating according to claim 1, characterized in that: The yttrium-doped zinc oxide has a particle size of 50 nanometers.

7. A method for preparing a yttrium-doped zinc oxide anti-corrosion and heat-insulating coating for the inner wall of a water pipe according to any one of claims 1 to 6, characterized in that: The specific steps include the following: S1: Add the diluent, functional additives, and base emulsion to a high-speed mixer and stir at 1200~1800 r / min for 10~20 min until homogeneous; S2: After adding silicone oil and polysiloxane elastomer microspheres, continue stirring at a speed of 1200~1800 r / min for 15~25 min; S3: After adding the hydrophobic aerogel, continue stirring at 1200~1800 r / min for 15~25 min; S4: After adding the inorganic compound, continue stirring at 1200~1800 r / min for 15~25 min; S5: After adding the binder, nano silver, nano ATO, nano zirconium oxide, and yttrium-doped zinc oxide, continue stirring at a speed of 1200~1800 r / min for 15~25 min; S6: Finally, add leveling agent, wetting agent and dispersant, and stir at 800~1000 r / min for 8~10 min to obtain coating mixture; S7: Spray, coat or brush the coating mixture onto the inner wall surface of the water pipe and heat it to 60~80℃ for 3~4 hours to cure; or let it air dry at room temperature for 24 hours to obtain the yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic heat insulation coating.

8. The application of the yttrium-doped zinc oxide water pipe inner wall anti-corrosion elastic thermal insulation coating according to any one of claims 1 to 7, characterized in that: The coating is used for heat insulation, corrosion protection, and anti-condensation treatment of the inner walls of various water pipes such as galvanized pipes, PPR pipes, stainless steel pipes, and PVC pipes. It can be used for new pipe prefabrication or old pipe renovation, and is especially suitable for drinking water pipes, hot and cold water pipes, and HVAC pipes.