Fe3O4 / PVA magnetic composite waterproof coiled material and preparation method and magnetic induction nondestructive testing method thereof

Abstract

The invention relates to the field of waterproof materials and waterproof leakage detection, and particularly discloses a Fe3O4 / PVA magnetic composite waterproof coiled material and a preparation method and a magnetic induction nondestructive testing method thereof. The invention provides a Fe3O4 / PVA magnetic composite waterproof coiled material which comprises an upper isolation layer, a tire base layer and a lower isolation layer which are sequentially arranged in a stacked mode, and the two faces of the tire base layer are coated with Fe3O4 / PVA magnetic composite modified asphalt mastic. The Fe3O4 / PVA magnetic composite modified asphalt mastic is prepared from the following raw material components in parts by weight: petroleum asphalt, a styrene-butadiene-styrene block copolymer, a filling agent, softening oil, magnetic nano Fe3O4 particles and polyvinyl alcohol. The high-performance SBS modified asphalt is used as a core and is matched with the function of the Fe3O4 / PVA functional unit, so that the prepared waterproof coiled material has the waterproof performance and the magnetic response characteristic, the rapid and non-contact magnetic induction detection technology is matched, and the effect of improving the engineering waterproof reliability and the maintenance efficiency is achieved.

Description

Technical Field

[0001] This application relates to the field of waterproof materials, and in particular to a Fe3O4 / PVA magnetic composite waterproof membrane, its preparation method, and a magnetic non-destructive testing method. Background Technology

[0002] With the rapid development of the construction industry, building leakage problems have become increasingly prominent, seriously affecting residents' quality of life and building safety, while also increasing maintenance costs. Traditional waterproof membranes (such as asphalt-based and polymer materials) are core materials for engineering waterproofing, but their application still suffers from problems such as joint leakage and difficulty in real-time damage monitoring, making it difficult to meet long-term durability requirements. Existing methods for detecting damage to waterproof layers mostly rely on manual visual inspection or core sampling, which are inefficient and make it difficult to achieve non-destructive identification of hidden defects.

[0003] Existing magnetic PVA composite materials are mostly focused on the biomedical or energy fields, with research emphasizing biocompatibility or electrochemical properties rather than applications in building waterproofing. A patent (CN105976971A) proposes a graphene-iron tetroxide-polyvinyl alcohol magnetic composite material for use in coatings, emulsifiers, and other products. Its preparation requires synthesis in an aqueous phase via co-precipitation, but actual production demands high-level and complex equipment and processes, limiting its commercial application.

[0004] The patent with announcement number CN208152405U describes a magnetic waterproof membrane that enhances adhesion through the magnetic adsorption of hard and soft magnetic materials. However, it only achieves physical adhesion and cannot monitor damage such as membrane cracking or substrate peeling through changes in magnetic signals. As a result, the risk of leakage needs to be detected by manual visual inspection, which is significantly different from the industry's urgent need for "real-time monitoring".

[0005] Therefore, developing a roll material that combines waterproofing performance with magnetic response characteristics, along with a rapid, non-contact magnetic sensing technology, is of great significance for improving the reliability and maintenance efficiency of waterproofing projects. Summary of the Invention

[0006] This application provides a Fe3O4 / PVA magnetic composite waterproof membrane, its preparation method, and a magnetic non-destructive testing method. It combines waterproof performance and magnetic response characteristics, and is equipped with a rapid, non-contact magnetic detection technology, which can improve the reliability of engineering waterproofing and maintenance efficiency.

[0007] In a first aspect, the Fe3O4 / PVA magnetic composite waterproof membrane provided in this application adopts the following technical solution: A Fe3O4 / PVA magnetic composite waterproof membrane includes an upper isolation layer, a base layer, and a lower isolation layer stacked sequentially. Both sides of the base layer are coated with Fe3O4 / PVA magnetic composite modified bitumen adhesive. The Fe3O4 / PVA magnetic composite modified bitumen adhesive includes the following raw material components in parts by weight: 40-80 parts of petroleum asphalt; 1-20 parts of styrene-butadiene-styrene block copolymer; 30-50 parts of filler; 3-7 parts of softening oil; 0.05-5 parts of magnetic nano Fe3O4 particles; and 1-10 parts of polyvinyl alcohol.

[0008] Through the above technical solution, petroleum asphalt, as the core matrix of the waterproof membrane, provides crucial basic adhesion, sealing, and waterproof barrier functions. Styrene-butadiene-styrene block copolymer (SBS) is incorporated as a key modifier, its unique block structure (polystyrene and polybutadiene blocks) forming a cross-linked network with the petroleum asphalt. This synergistic effect enhances the material's performance: the polystyrene blocks of SBS significantly enhance the system's strength and high-temperature stability; simultaneously, the polybutadiene blocks greatly improve elasticity and low-temperature flexibility, preventing low-temperature brittleness. Together, these two components transform the modified asphalt adhesive from a simple thermoplastic material into a thermoplastic elastomer with excellent comprehensive properties (high strength, high elasticity, resistance to high and low temperatures, and fatigue resistance), laying a high-performance foundation for the entire waterproof membrane.

[0009] Based on the elastic cross-linked network formed by this SBS-modified asphalt, fillers are uniformly dispersed within it. The fillers not only effectively reduce costs but, more importantly, increase the volume and thickness of the material, improving compressive strength and dimensional stability, and contributing to improved heat resistance and abrasion resistance. The addition of a large amount of filler, along with the increased stiffness and viscosity of the SBS cross-linked network itself, provides a crucial balancing effect. The softening oil penetrates the network, reducing overall viscosity and significantly improving mixing and coating performance during high-temperature processing. More importantly, it moderately softens the system, replenishes low-molecular-weight components, and synergistically enhances the low-temperature flexibility and plasticity of the composite compound, avoiding the brittleness and hardness tendencies caused by excessive fillers or SBS. This combination of fillers and softening oil in the SBS / asphalt matrix optimizes the material's processability, mechanical properties, and cost-effectiveness.

[0010] Most importantly, it incorporates the functional combination of magnetic Fe3O4 nanoparticles and polyvinyl alcohol (PVA). The core function of PVA lies in the effective adsorption and coating of Fe3O4 nanoparticles by the hydroxyl groups on its molecular chain. This steric hindrance prevents the nanoparticles from agglomerating and settling in the asphalt matrix, ensuring uniform and stable dispersion. This excellent dispersion achieved by PVA is a prerequisite for the Fe3O4 particles to fully utilize their magnetism and impart magnetic response characteristics (such as magnetic positioning and post-detection) to the entire modified asphalt adhesive layer. A small amount of well-dispersed Fe3O4 / PVA composite units are uniformly dispersed within the elastic network of SBS modified asphalt, synergizing well with the existing high-performance SBS modified asphalt matrix, filler reinforcement system, and softening oil plasticizer system. This achieves an effective fusion of basic waterproofing performance and innovative magnetic response characteristics while maintaining the material's original excellent waterproofing, mechanical properties, and flexibility.

[0011] Optionally, the petroleum asphalt is selected from one or more of No. 90 asphalt, No. 130 asphalt, and No. 200 asphalt.

[0012] Through the above technical solutions, different asphalts exhibit varying properties. 90-grade asphalt is harder but has good high-temperature stability; 200-grade asphalt is softer but has excellent low-temperature flexibility; and 130-grade asphalt offers a balanced performance. By selecting 90-grade, 130-grade, and 200-grade asphalt individually or in combination, and adjusting the penetration, the high-temperature anti-flow properties and low-temperature flexibility of the roll material can be synergistically optimized, significantly broadening the applicable temperature range.

[0013] Optionally, the filler is selected from one or more of light calcium carbonate powder, heavy calcium carbonate powder, and talc powder.

[0014] Through the above technical solutions, light calcium carbonate powder, heavy calcium carbonate powder, and talc are all inorganic fillers, but their properties differ significantly. Light calcium carbonate powder has a low bulk density and high oil absorption value, which can improve the stiffness of the compound but may increase viscosity; heavy calcium carbonate powder has a high density, low cost, and good filling effect; talc powder's flake structure can improve dimensional stability and heat resistance. By selecting light calcium carbonate powder, heavy calcium carbonate powder, or talc powder alone or in combination, the cost, processability, mechanical strength, and thermal stability of the compound can be flexibly optimized, supporting the performance of SBS modified asphalt network.

[0015] Optionally, the softening oil is selected from one or more of paraffinic oils, aromatic oils, and naphthenic oils.

[0016] Through the above technical solutions, paraffinic oil, aromatic oil, and naphthenic oil each have their own characteristics. Paraffinic oil has good low-temperature performance but slightly weaker compatibility; aromatic oil has the best compatibility but poor environmental performance; and naphthenic oil has excellent balance. By selecting paraffinic oil, aromatic oil, or naphthenic oil alone or in combination, the plasticization degree and processing fluidity of SBS modified asphalt network can be precisely controlled, and the high-temperature workability and low-temperature crack resistance of the compound can be synergistically optimized.

[0017] Optionally, the upper insulating layer is either a polyethylene film or a polypropylene film.

[0018] Optionally, the lower separator layer is either a polyethylene film or a polypropylene film.

[0019] Optionally, the tire base layer is a polyester tire.

[0020] Through the above technical solutions, both polyethylene (PE) and polypropylene (PP) films are excellent waterproof and insulating materials, possessing high water resistance, tear resistance, and flexibility. PE films are low-cost and flexible, while PP films are more heat-resistant. By selecting PE or PP films as the upper and lower insulating layers, the roll material's anti-stick properties and ease of construction are ensured. Combined with a high-strength, highly elongated, and dimensionally stable polyester base, they provide strong support and synergistic protection for the intermediate Fe3O4 / PVA magnetic composite modified bitumen adhesive layer.

[0021] Secondly, this application provides a method for preparing a Fe3O4 / PVA magnetic composite waterproof membrane, employing the following technical solution: A method for preparing a Fe3O4 / PVA magnetic composite waterproof membrane includes the following steps: S1. Place petroleum asphalt in a reaction vessel, stir and heat to 180-190℃, then add styrene-butadiene-styrene block copolymer (SBS), softening oil, nano Fe3O4 particles and polyvinyl alcohol. Continue stirring and mixing the resulting mixture at 180-190℃ for 2.5-3.5h. After repeated grinding of the colloid, add filler and stir for 1.5-2.5h to obtain Fe3O4 / PVA magnetic composite modified asphalt adhesive. S2. Place the Fe3O4 / PVA magnetic composite modified bitumen adhesive into the impregnation tank and control the temperature of the impregnation tank at 185±1℃ to ensure that the modified bitumen adhesive completely penetrates the base layer and completes the impregnation of the base layer. S3. Cover the upper surface of the Fe3O4 / PVA magnetic composite modified bitumen base layer, which is coated on both sides, with an isolation layer, and cover the lower surface with a lower isolation layer; then cool and pull to obtain a waterproof material; then measure, roll and inspect to make a waterproof membrane.

[0022] The above technical solution involves simultaneous high-temperature mixing at 180-190℃ (S1), where Fe3O4, PVA, and SBS modified bitumen are blended and ground to ensure that PVA fully coats Fe3O4 and stably embeds it into the bitumen network. This process, while guaranteeing excellent waterproofing and mechanical properties, embeds uniformly distributed magnetic functional units into the material. Following this, precise temperature-controlled impregnation (S2, 185±1℃) ensures that the molten rubber completely penetrates the base material, allowing the magnetic units to form a continuous and uniform overall magnetic response layer within the base layer. The resulting roll material thus possesses highly sensitive "passive" magnetic response characteristics, facilitating construction positioning and subsequent tracking with the aid of readily responsive magnets or detection equipment.

[0023] Thirdly, this application provides a non-destructive magnetic testing method for Fe3O4 / PVA magnetic composite waterproof membrane, comprising the following steps: S1. Magnetize the structure on which Fe3O4 / PVA magnetic composite waterproof membrane has been applied using a stable neodymium iron boron magnet; S2. Use a gaussmeter to measure the magnetic induction intensity of the magnetized Fe3O4 / PVA magnetic composite waterproof membrane.

[0024] The above technical solution is highly compatible with the characteristics of Fe3O4 / PVA magnetic composite waterproof membrane, utilizing the uniformly dispersed Fe3O4 / PVA units within its base layer as built-in "magnetic marker sources." During operation, a strong neodymium iron boron magnet is used to momentarily magnetize the target area, causing the magnetic units to generate stable remanence. A portable gaussmeter is then used to measure the magnetic induction intensity. This process is straightforward and simple to operate (magnetization + measurement), requiring no complex equipment or structural damage. It allows for non-contact, quantitative acquisition of potential defects in the membrane, particularly abnormal signals at damaged or leaking locations. This breakthrough solves the challenge of non-destructive testing in covered, concealed works, enabling efficient, widely applicable, and visualized quality monitoring of the entire lifecycle of the waterproof layer (construction, acceptance, and maintenance), providing the membrane industry with an innovative engineering testing tool.

[0025] In summary, this application includes at least one of the following beneficial effects: 1. With high-performance SBS modified bitumen as the core, petroleum bitumen provides basic waterproof sealing, SBS polymer forms a strong and elastic network with it, and fillers and softening oil synergistically optimize cost, strength and flexibility to ensure a durable and reliable waterproof barrier in various environments. 2. Fe3O4 / PVA functional units are introduced, in which PVA molecules effectively coat Fe3O4 nanoparticles, preventing them from agglomerating in the asphalt and achieving uniform dispersion. A small amount of well-dispersed magnetic Fe3O4 units are embedded in the asphalt network, which, while maintaining excellent waterproofing, endows the base layer with overall, sensitive magnetic response characteristics. 3. By cleverly utilizing the built-in magnetism of the roll material through a complementary method, a strong magnet instantaneously magnetizes and excites residual magnetism, while a portable gaussmeter is placed close to measure the signal intensity. The operation is extremely simple and non-destructive, enabling quantitative detection of the roll material's location, coverage integrity, and potential defects, especially seam leaks and waterproof layer damage. This effectively solves the challenges of non-destructive testing and full life-cycle monitoring of waterproof layers in concealed projects. Detailed Implementation

[0026] Example 1 This embodiment provides a Fe3O4 / PVA magnetic composite waterproof membrane, the composition of which is shown in Table 1.

[0027] Table 1. Composition of Fe3O4 / PVA magnetic composite modified asphalt adhesive provided in Example 1. A method for preparing Fe3O4 / PVA magnetic composite waterproof membrane includes the following steps: S1. Place petroleum asphalt in a reaction vessel, stir and heat to 185°C, then add SBS, naphthenic oil, magnetic nano Fe3O4 particles and polyvinyl alcohol (PVA). Continue stirring and mixing the resulting mixture at 185°C for 2.5 hours. After repeated grinding of the colloid, add heavy calcium carbonate powder and stir for 1.5 hours to obtain Fe3O4 / PVA magnetic composite modified asphalt adhesive. S2. Place the Fe3O4 / PVA magnetic composite modified bitumen adhesive into the impregnation tank, select polyester felt as the base material, and control the temperature of the impregnation tank at 185±1℃ to ensure that the modified bitumen adhesive completely penetrates the base material and completes the impregnation of the base material. S3. A polyethylene film isolation layer is applied to the upper surface of the Fe3O4 / PVA magnetic composite modified asphalt rubber base layer, which is coated on both sides, and a polyethylene film isolation layer is applied to the lower surface; then, after cooling and traction, a waterproof material is obtained; and then, after measurement, rolling, and inspection, it is made into a waterproof roll.

[0028] Example 2 The difference between this embodiment and Embodiment 1 lies in adjusting the specifications of the asphalt. The type and weight fraction of the filler are also adjusted. The components of this waterproof coating are shown in Table 2.

[0029] Table 2. Composition of Fe3O4 / PVA magnetic composite modified asphalt adhesive provided in Example 2. Raw material name Specifications and Models Number of weights asphalt No. 130 250 SBS - 20 softening oil Naphthenic oil 50 filler talcum powder 300 <![CDATA[Magnetic nano-Fe3O4 particles]]> - 20 Polyvinyl alcohol (PVA) - 20 Example 3 The difference between this embodiment and Example 1 is that the weight proportions of SBS, magnetic nano Fe3O4 particles, and polyvinyl alcohol (PVA) were adjusted. The composition of this waterproof coating is shown in Table 3.

[0030] Table 3. Composition table of Fe3O4 / PVA magnetic composite modified asphalt adhesive provided in Example 3. Raw material name Specifications and Models Number of weights asphalt No. 90 250 SBS - 30 softening oil Naphthenic oil 50 filler Heavy calcium powder 350 <![CDATA[Magnetic nano-Fe3O4 particles]]> - 15 Polyvinyl alcohol (PVA) - 25 Comparative Example 1 The difference between this comparative example and Example 1 is that no magnetic nano Fe3O4 particles and polyvinyl alcohol (PVA) were added.

[0031] Comparative Example 2 The difference between this comparative example and Example 1 is that polyvinyl alcohol (PVA) was not added.

[0032] Comparative Example 3 The difference between this comparative example and Example 1 is that No. 90 asphalt is replaced with an equal amount of No. 70 asphalt.

[0033] Detection Example 1 The waterproof membranes provided in Examples 1-3 and Comparative Examples 1-3 were tested in accordance with the current national standard GB18242-2008 "Elastomer Modified Bituminous Waterproof Membranes". The test results are shown in Table 4.

[0034] Table 4 Detection Example 2 The magnetic induction intensity of the Fe3O4 / PVA magnetic composite waterproof membrane was measured using a gaussmeter after magnetizing the waterproof membrane provided in Examples 1-3 with an iron boron magnet.

[0035] A magnetic non-destructive testing method for Fe3O4 / PVA magnetic composite waterproof membrane, the specific method includes the following steps: S1, magnetizing the structure on which the Fe3O4 / PVA magnetic composite waterproof membrane has been applied using a stable neodymium iron boron magnet; S2. Use a gaussmeter to measure the magnetic induction intensity of the magnetized Fe3O4 / PVA magnetic composite waterproof membrane.

[0036] The test results are shown in Table 5.

[0037] Table 5 Magnetic field strength / mt Example 1 Example 2 Example 3 Normal area 1.51 1.34 1.39 Leakage area 0.62 0.74 0.68 As shown in Table 4 of the performance test data of Examples 1-3 and Comparative Examples 1-3, the selection of asphalt type has a significant impact on the tensile strength of the membrane. In particular, by compounding different types of asphalt, the membrane can combine the advantages of different types of asphalt, thereby improving the tensile strength. At the same time, the introduction of Fe3O4 / PVA functional unit has a beneficial effect on the strength of waterproof membrane.

[0038] As shown in Table 5 of the performance test data of Examples 1-3, the introduction of the Fe3O4 / PVA functional unit enables the roll material to have magnetic induction properties. The detection method provided in this application can determine the area of ​​leakage or damage by the change in magnetic field strength.

[0039] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A Fe3O4 / PVA magnetic composite waterproof membrane, comprising an upper insulating layer, a base layer, and a lower insulating layer stacked sequentially, characterized in that: Both sides of the base layer are coated with Fe3O4 / PVA magnetic composite modified asphalt adhesive, which comprises the following raw material components in parts by weight: 200-300 parts of petroleum asphalt; 10-50 parts of styrene-butadiene-styrene block copolymer; 300-500 parts of filler; 30-70 parts of softening oil; 10-50 parts of magnetic nano Fe3O4 particles; and 10-50 parts of polyvinyl alcohol.

2. The Fe3O4 / PVA magnetic composite waterproof membrane according to claim 1, characterized in that: The petroleum asphalt is selected from one or more of No. 90 asphalt, No. 130 asphalt, and No. 200 asphalt.

3. The Fe3O4 / PVA magnetic composite waterproof membrane according to claim 1, characterized in that: The filler is selected from one or more of light calcium carbonate powder, heavy calcium carbonate powder, and talc powder.

4. The Fe3O4 / PVA magnetic composite waterproof membrane according to claim 1, characterized in that, The softening oil is selected from one or more of paraffinic oils, aromatic oils, and naphthenic oils.

5. The Fe3O4 / PVA magnetic composite waterproof membrane according to claim 1, characterized in that: The upper isolation layer is either a polyethylene film or a polypropylene film.

6. The Fe3O4 / PVA magnetic composite waterproof membrane according to claim 1, characterized in that: The lower isolation layer is either a polyethylene film or a polypropylene film.

7. The Fe3O4 / PVA magnetic composite waterproof membrane according to claim 1, characterized in that: The base layer is made of polyester.

8. A method for preparing a Fe3O4 / PVA magnetic composite waterproof membrane according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Place petroleum asphalt in a reaction vessel, stir and heat to 180-190℃, then add styrene-butadiene-styrene block copolymer, softening oil, nano Fe3O4 particles and polyvinyl alcohol. Continue stirring and mixing the resulting mixture at 180-190℃ for 2.5-3.5h. After repeated grinding of the colloid, add filler and stir for 1.5-2.5h to obtain Fe3O4 / PVA magnetic composite modified asphalt adhesive. S2. Place the Fe3O4 / PVA magnetic composite modified bitumen adhesive into the impregnation tank and control the temperature of the impregnation tank at 185±1℃ to ensure that the modified bitumen adhesive completely penetrates the base layer and completes the impregnation of the base layer. S3. Cover the upper surface of the Fe3O4 / PVA magnetic composite modified bitumen base layer, which is coated on both sides, with an isolation layer, and cover the lower surface with a lower isolation layer; then cool and pull to obtain a waterproof material; then measure, roll and inspect to make a waterproof membrane.

9. A non-destructive testing method for magnetic induction of a Fe3O4 / PVA magnetic composite waterproof membrane according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Magnetize the structure on which Fe3O4 / PVA magnetic composite waterproof membrane has been applied using a stable neodymium iron boron magnet; S2. Use a gaussmeter to measure the magnetic induction intensity of the magnetized Fe3O4 / PVA magnetic composite waterproof membrane.

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