Two-component polyurethane spray material, its preparation method and application

Abstract

The application discloses a kind of two-component polyurethane spray materials and its preparation method and application, including following weight parts of each raw material component: A component isocyanate prepolymer: poly methylene polyphenyl polyisocyanate 42-46 parts, polyethylene glycol adipate diol 54-58 parts;B component polyol compound: main polyol 33-40 parts, modifier 13-17 parts, catalyst 0.8-1.2 parts, functional additive 5.3-7.8 parts, rigid filler 55-65 parts;The mass ratio of A component and B component is 1: (2.0-2.5), and the equivalent ratio of isocyanate group in A component and hydroxyl in B component is (1.05-1.15):1.The application realizes extremely fast curing, super high structural strength, controllable rigid and tough balance, excellent wet base surface adaptability and long-term corrosion and wear resistance by precise molecular structure design, low-cost nano filler synergistic reinforcement and additive system optimization.

Description

Technical Field

[0001] This invention relates to the field of pipeline repair materials technology, specifically to a two-component polyurethane spraying material and its preparation method and application. Background Technology

[0002] As urban underground pipe networks age, problems such as aging, leakage, structural damage, corrosion, and collapse become increasingly prominent, directly impacting urban drainage and flood control safety, water environment management, and public safety. Trenchless repair technology, due to its high construction efficiency, minimal disruption to surface traffic and the surrounding environment, low overall construction cost, and excellent life-cycle benefits, has become the core development direction of the urban underground pipe network repair industry.

[0003] Currently, commonly used materials for trenchless repair of underground pipelines face significant technical bottlenecks, failing to balance construction efficiency, structural strength, environmental adaptability, long-term service performance, and the cost of large-scale promotion. Traditional cement mortar and polymer concrete repair materials suffer from fundamental defects such as low hardness, poor wear resistance, poor chemical corrosion resistance, and insufficient crack resistance. Long-term service often leads to cracking, detachment, and leakage, providing only surface repair and failing to achieve structural restoration. UV-cured and in-situ thermosetting resins suffer from slow curing speeds, long construction cycles, and stringent requirements for pipeline pretreatment. Furthermore, cured materials lack flexibility and have poor resistance to settlement and deformation, making them prone to brittle failure in areas with geological fluctuations. While polyurea repair materials cure quickly, they are highly sensitive to environmental humidity and substrate cleanliness. In high-humidity environments like underground pipe networks, they are prone to blistering, a sharp drop in adhesion, and interlayer separation. Moreover, their high raw material costs and stringent equipment requirements hinder large-scale adoption. Ordinary fast-curing polyurethane materials, in pursuit of rapid curing, drastically adjust the catalyst system and crosslinking density, sacrificing mechanical strength, corrosion resistance, and durability. They only provide functional repairs such as seepage prevention and corrosion protection, failing to meet the structural reinforcement needs of damaged pipelines, and are prone to performance degradation over long-term service.

[0004] In summary, existing technologies cannot simultaneously meet the core requirements of "rapid construction, high structural strength, strong environmental adaptability, long service life, and low cost and scalability" for trenchless repair of underground pipelines. The industry urgently needs a new generation of low-cost, high-performance polyurethane spraying material that can achieve structural repair. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a two-component polyurethane spraying material, its preparation method, and its application. Through precise molecular structure design, low-cost nanofiller synergistic enhancement, and additive system optimization, it simultaneously achieves rapid curing, ultra-high structural strength, controllable rigidity-toughness balance, excellent compatibility with damp substrates, and long-lasting corrosion and wear resistance. Under the premise of fully meeting the core performance standards, it significantly reduces raw material costs and meets the core needs of underground pipeline structural repair.

[0006] To address the aforementioned technical problems, this invention provides a two-component polyurethane spraying material, comprising the following raw material components in parts by weight:

[0007] Component A isocyanate prepolymer: 42-46 parts of polymethylene polyphenyl polyisocyanate, 54-58 parts of polyethylene adipate diol;

[0008] Component B polyol complex: 33-40 parts of main polyol, 13-17 parts of modifier, 0.8-1.2 parts of catalyst, 5.3-7.8 parts of functional additives, and 55-65 parts of rigid filler;

[0009] The mass ratio of the isocyanate prepolymer of component A to the polyol complex of component B is 1:(2.0-2.5), and the equivalent ratio of the isocyanate groups in the isocyanate prepolymer of component A to the hydroxyl groups in the polyol complex of component B is (1.05-1.15):1.

[0010] Furthermore, the NCO content in the polymethylene polyphenyl polyisocyanate is 29.5%-30.5%, the moisture content is ≤0.05%, and it is selected from PAPI (polyphenyl polymethylene polyisocyanate, polymeric MDI) and / or MDI (diphenylmethane diisocyanate).

[0011] The polyethylene adipate diol has a number-average molecular weight of 1900-2100, a hydroxyl value of 55-60 mgKOH / g, an acid value ≤0.2 mgKOH / g, and a moisture content ≤0.05%. Preferably, the NCO content in the isocyanate prepolymer of component A is 8.0%-9.0%.

[0012] Furthermore, the main polyol comprises polybutylene adipate diol and polypropylene glycol in a mass ratio of (2-4):1;

[0013] The polybutylene adipate diol has a number-average molecular weight of 950-1050 and a hydroxyl value of 105-115 mgKOH / g, providing the material with rigidity, hydrolysis resistance, and resistance to media corrosion; the polypropylene glycol has a number-average molecular weight of 2800-3200 and a hydroxyl value of 33-37 mgKOH / g, used to balance the toughness of the material in the high-filler system, avoid material brittleness, and achieve a balance between rigidity and toughness.

[0014] Furthermore, the modifier comprises bisphenol A epoxy resin E-51 and castor oil in a mass ratio of (8-10):(5-7). Preferably, the bisphenol A epoxy resin E-51 has an epoxy value of 0.48-0.54 eq / 100g, and improves the tensile strength, flexural properties, and chemical corrosion resistance of the material through grafting reactions of epoxy groups, hydroxyl groups, and isocyanate groups; the castor oil is a bio-based polyol with a functionality of 2.7 and a hydroxyl value of 160-170 mgKOH / g, which can improve the compatibility of components in the high-filler system, while reducing dependence on petroleum-based raw materials and improving the environmental friendliness of the material.

[0015] Furthermore, the catalyst comprises a dibutyltin dilaurate, a bismuth-zinc composite catalyst, and triethylenediamine in a mass ratio of (0.8-1.2):(1.0-1.2):(0.8-1.2). This composite catalyst balances the gelation and cross-linking reaction rates, achieving ultra-fast gelation in 3-10 seconds without sagging, while avoiding coating defects caused by vigorous reactions; it significantly reduces the amount of organotin catalyst used, ensuring environmental compliance; and it counteracts the adsorption effect of high filler on the catalyst, guaranteeing complete curing of the system.

[0016] Furthermore, the functional additives include the following components in parts by weight: 1.5-2.5 parts of polymeric dispersant BYK-110, 2.0-3.0 parts of silane coupling agents KH-550 and KH-560 in a mass ratio of 2:(0.5-1.5), 0.5-1.0 parts of non-silicone defoamer BYK-066N and organosilicon defoamer BYK-024 in a mass ratio of 2:(0.5-1.5), and 0.3-0.5 parts of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:(0.5-2). Among them, the polymeric dispersant BYK-110 can anchor on the filler surface to achieve uniform dispersion of the high-filler system, reduce system viscosity, prevent nanofiller agglomeration, and ensure material performance stability; the silane coupling agent is compounded with KH-550 and KH-560. KH-550 is used for filler surface modification and to improve the adhesion of inorganic substrates, while KH-560 can work synergistically with epoxy resin to improve the interfacial bonding force between resin and filler, avoid interfacial weaknesses in the high-filler system, and further improve the adhesion performance of damp substrates; the compounded defoamer takes into account both the foam suppression and defoaming effects of high-viscosity systems, eliminates bubbles generated during preparation and spraying, avoids pinholes and defects in the coating, and does not affect the adhesion between the material and the substrate; the compounded antioxidant, through the synergistic effect of primary and secondary antioxidants, inhibits the aging and degradation of the material in a thermo-oxidative environment, improves the long-term performance stability of the material, and extends its service life.

[0017] Furthermore, the rigid filler comprises hydrophobic fumed silica, α-phase alumina, ultrafine calcium carbonate and ultra-short chopped glass fibers in a mass ratio of (1-3):1:(30-35):(5-7).

[0018] The hydrophobic fumed silica nanoparticles have a particle size of 50-100 nm and a specific surface area of ​​200±20 m². 2 / g, hydrophobicity ≥40%, can improve the crosslinking density, hardness and wear resistance of the matrix, and at the same time has a thixotropic effect to improve the anti-sagging properties of spray coating;

[0019] The α-phase nano-alumina has a particle size of 80-100nm, a purity of ≥99.5%, and a Mohs hardness of 9, which can perfectly match the reinforcing effect of high-priced nano-silicon nitride, improving the material's rigidity, wear resistance, and corrosion resistance.

[0020] The ultrafine calcium carbonate has a particle size of 1-3 μm and an activation degree of ≥95%, which can improve the processability of the material and reduce the shrinkage rate and raw material cost of the system.

[0021] The ultra-short chopped glass fiber is a silane-modified alkali-free glass fiber with a length of 0.1-0.3 mm. It can improve the material's impact resistance, sedimentation resistance, and dimensional stability, while also being compatible with high-pressure airless spraying processes to avoid gun clogging.

[0022] The compound filler system of this invention, through the synergistic effect of "nano-reinforcement + micron filling + fiber toughening", can still ensure the continuity of the material matrix at high addition levels, achieving a leapfrog improvement in the structural strength of the material. At the same time, the cost is reduced by more than 70% compared with the original high-priced nano-filler system, which is the core foundation for achieving low-cost structural repair.

[0023] A second aspect of the present invention provides a method for preparing the two-component polyurethane spraying material described in the first aspect, comprising the following steps:

[0024] Preparation of S1 and A components

[0025] (1) Under a protective atmosphere and at 68-72℃, polymethylene polyphenyl polyisocyanate is added dropwise to the vacuum-dried polyethylene adipate diol at a rate of 1.5-2 kg / h and reacted. The reaction is terminated when the NCO content in the reaction system reaches 8.0%-9.0%. Specifically, the vacuum drying is as follows: polyethylene adipate diol is added to the reaction vessel, the vacuum system is turned on, the vacuum degree is controlled to be ≤-0.1 MPa, the temperature is raised to 105-110℃, the water content is dehydrated for 2.5-3 hours until the moisture content is ≤0.05%, and the temperature is lowered to 60℃ for later use.

[0026] (2) Cool down to below 40°C, degas under vacuum, filter, and seal with nitrogen to obtain component A;

[0027] Preparation of components S2 and B

[0028] (1) The rigid filler dried in a forced-air oven at 110-130℃ is mixed with 45-55 wt% of the total amount of silane coupling agent and then dry surface modified at 75-85℃.

[0029] (2) Mix the main polyol and castor oil and vacuum dry (115-120℃, vacuum degree ≤-0.1MPa), dehydrate to a moisture content ≤0.05wt%, cool to 80-90℃, add bisphenol A epoxy resin E-51 for epoxy modification; then add catalyst, remaining silane coupling agent, polymeric dispersant, defoamer and antioxidant in sequence, and mix to form a uniform mixture system;

[0030] (3) Cool the mixture to 65-70℃, add the rigid filler modified in step (1) and disperse it at high speed (3400-3600r / min), then transfer it to a horizontal sand mill and grind it to a fineness of ≤20μm;

[0031] (4) Cool down to below 40°C, degas under vacuum, filter, and seal with nitrogen to obtain component B;

[0032] S3. Store components A and B in a sealed container at room temperature, dry and protected from light (shelf life 6 months). Mix them on-site according to the specified ratio before construction to obtain a two-component polyurethane spraying material.

[0033] Furthermore, S1 and S2 control the relative humidity of the production environment to ≤40% throughout the entire process.

[0034] The third aspect of this invention provides the application of the two-component polyurethane spraying material described in the first aspect in trenchless structural repair of underground pipe networks, wherein the underground pipe network includes concrete drainage pipes, inspection wells, underground integrated pipe corridors and steel water transmission pipes, and the two-component polyurethane spraying material is applied by spraying with a high-pressure airless spraying device with a working pressure ≥20MPa.

[0035] The beneficial effects of this invention are:

[0036] This invention achieves a breakthrough balance in material performance through precise molecular structure design and cross-linking system optimization. It gels and cures within 3-10 seconds after spraying, without sagging, making it suitable for rapid trenchless repair applications and significantly shortening construction cycles and pipeline sealing times. Simultaneously, through an optimized polyol compound system and a "nano-micro-fiber" synergistic reinforcement filler system, the material's elongation at break is stably controlled above 5% while maintaining ultra-high filler reinforcement. It balances tensile strength ≥60MPa, flexural modulus ≥5000MPa, and excellent deformation resistance, solving the problem of brittleness in traditional high-rigidity materials. This enables structural reinforcement and repair of underground pipelines, rather than simply seepage prevention and corrosion protection, and its overall performance surpasses that of traditional polyurea and ordinary polyurethane materials.

[0037] The material system of this invention has excellent environmental compliance: it uses low-volatility, low-toxicity PAPI and / or MDI to replace high-volatility TDI, which significantly reduces VOC emissions during construction; by compounding environmentally friendly bismuth-zinc catalysts, it reduces the amount of organotin catalysts by more than 80%; at the same time, it introduces bio-based castor oil modification to reduce dependence on petroleum-based raw materials, with VOC content ≤100g / L, which is in line with the development trend of green municipal building materials.

[0038] The formulation system and preparation process of this invention are highly adaptable to industrial production and on-site engineering applications: the preparation process strictly controls core parameters such as moisture, reaction temperature, and dispersion fineness throughout the process, ensuring good batch consistency and enabling large-scale stable production; the materials are compatible with conventional high-pressure airless spraying equipment, enabling layered controllable spraying, controllable single-coat thickness and forming effect, simple construction process, strong adaptability to construction personnel and on-site environment, controllable overall cost, and has the value for large-scale promotion and application. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] This embodiment relates to a method for preparing a two-component polyurethane spraying material, wherein, by mass parts,

[0042] Component A raw material composition: 45 parts of 44V20 type PAPI, 55 parts of polyethylene adipate diol PEA-2000; the final NCO content of the component A prepolymer is 8.6%.

[0043] Component B consists of: 27 parts polybutylene adipate diol PBA-1000, 9 parts polypropylene glycol PPG-3000, 9 parts bisphenol A epoxy resin E-51, 6 parts castor oil, 1.0 part compound catalyst, 2.0 parts polymeric dispersant BYK-110, 2.5 parts compound silane coupling agent, 0.7 parts composite defoamer, 0.4 parts compound antioxidant, and 60 parts compound rigid filler.

[0044] Among them, the compound catalyst is formulated in the following mass ratio: dibutyltin dilaurate: bismuth zinc composite catalyst: triethylenediamine = 1:1:1; the compound silane coupling agent is formulated in the following mass ratio: KH-550: KH-560 = 2:1; the compound defoamer is formulated in the following mass ratio: BYK-066N: BYK-024 = 2:1; the compound antioxidant is formulated in the following mass ratio: 1010:168 = 1:1; and the compound rigid filler is formulated in the following mass ratio: hydrophobic fumed nano silica: α-phase nano alumina: ultrafine calcium carbonate: ultra-short chopped glass fiber = 2:1:30:6, with the ultra-short chopped glass fiber having a length of 0.2 mm.

[0045] The preparation method includes the following steps:

[0046] The material preparation method of this embodiment includes the following steps:

[0047] Preparation of S1 A component:

[0048] Raw material pretreatment: Add PEA-2000 to the reactor, turn on the vacuum system, control the vacuum degree to ≤-0.095MPa, heat to 108℃, dehydrate for 2.5 hours, cool to 60℃ for later use, and test the moisture content to be 0.03%;

[0049] Prepolymerization reaction: Under the protection of dry nitrogen, 44V20 type PAPI was added dropwise at a constant rate of 1.8 kg / h to the pretreated PEA-2000. The reaction temperature was maintained at 70℃ throughout the process. After the addition was completed, the reaction was kept at this temperature for 3 hours. The NCO content was measured and found to be 8.6%, which indicated that the reaction had reached its endpoint.

[0050] Post-processing: After the reaction is completed, the temperature is rapidly reduced to below 40°C, the mixture is degassed under vacuum for 30 minutes, impurities are removed by filtration through a 200-mesh filter, and the mixture is then sealed in nitrogen to obtain component A.

[0051] Preparation of S2 B component:

[0052] Filler pretreatment: The compound rigid filler was dried in a 120℃ forced-air oven for 2 hours. After cooling to room temperature, 1.25 parts (50%) of compound silane coupling agent were added. Dry surface modification was carried out in a high-speed mixer at a modification temperature of 80℃ for 30 minutes. The filler was then sealed for later use.

[0053] Polyol dehydration: PBA-1000, PPG-3000 and castor oil were added to the reactor, stirring was started, the speed was controlled at 180 r / min, the temperature was raised to 118℃, the vacuum degree was ≤-0.1MPa, and dehydration was carried out for 3 hours. The moisture content of the system was detected to be 0.02%. The temperature was then lowered to 85℃ and set aside for later use.

[0054] Modification and additives: Bisphenol A epoxy resin E-51 was added to the dehydrated polyol system cooled to 85℃ and stirred for 1.5 hours; then the compound catalyst, the remaining 1.25 parts (50%) of compound silane coupling agent, BYK-110 dispersant, composite defoamer, and compound antioxidant were added in sequence and stirred for 1 hour until the system was homogeneous;

[0055] Packing dispersion: Cool down to 70℃, turn on the high-speed disperser, control the speed at 3500r / min, add the pretreated compound rigid packing in 3 batches, with an interval of 20 minutes between each batch, disperse at high speed for 1.5 hours after all the packing is added, and then transfer to a horizontal sand mill to grind until the fineness of the system is 15μm.

[0056] Post-processing: Cool to below 40℃, degas under vacuum for 30 minutes, filter through a 200-mesh filter, fill with nitrogen and seal in packaging to obtain component B.

[0057] S3. Store components A and B in a sealed container at room temperature, dry and protected from light. Before construction, mix them on-site at a mass ratio of 1:2.2, with an NCO / OH equivalent ratio of 1.09, to obtain a two-component polyurethane spraying material.

[0058] Example 2

[0059] The difference between this embodiment and Embodiment 1 is that, by mass parts,

[0060] Component A raw material composition: 46 parts of 44V20 type PAPI, 54 parts of PEA-2000; the final NCO content of component A prepolymer is 8.9%.

[0061] Component B raw material composition: PBA-1000 30 parts, PPG-3000 10 parts, bisphenol A epoxy resin E-51 8 parts, castor oil 5 parts, compound catalyst 0.8 parts, BYK-110 dispersant 1.5 parts, compound silane coupling agent 2.0 parts, compound defoamer 0.5 parts, compound antioxidant 0.3 parts, compound rigid filler 55 parts;

[0062] The proportions and types of the compound catalyst, compound silane coupling agent, compound defoamer, compound antioxidant, and compound rigid filler are the same as in Example 1, and the length of the ultra-short chopped glass fiber is 0.15 mm.

[0063] The construction quality ratio of component A to component B is 1:2.0, the NCO / OH equivalent ratio is 1.12, and other steps and parameters remain unchanged to prepare a two-component polyurethane spraying material.

[0064] Example 3

[0065] The difference between this embodiment and Embodiment 1 is that, by mass parts,

[0066] Component A raw material composition: 42 parts of 44V20 type PAPI, 58 parts of PEA-2000; the final NCO content of component A prepolymer is 8.1%.

[0067] Component B raw material composition: PBA-1000 25 parts, PPG-3000 8 parts, bisphenol A epoxy resin E-51 10 parts, castor oil 7 parts, compound catalyst 1.2 parts, BYK-110 dispersant 2.5 parts, compound silane coupling agent 3.0 parts, compound defoamer 1.0 part, compound antioxidant 0.5 parts, compound rigid filler 65 parts;

[0068] The proportions and types of the compound catalyst, compound silane coupling agent, compound defoamer, compound antioxidant, and compound rigid filler are the same as in Example 1, and the length of the ultra-short chopped glass fiber is 0.3 mm.

[0069] The construction quality ratio of component A to component B is 1:2.5, the NCO / OH equivalent ratio is 1.06, and other steps and parameters remain unchanged to prepare a two-component polyurethane spraying material.

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 1 is that the composite rigid filler lacks ultra-short chopped glass fibers, while the remaining fillers are supplemented proportionally, and other steps and parameters remain unchanged.

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 1 is that in S2, the horizontal sand mill grinding step is omitted in the filler dispersion step, and the filler dispersion is completed only by high-speed dispersion, while other steps and parameters remain unchanged.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that the mass fraction of the rigid packing is adjusted to 40 parts, while other steps and parameters remain unchanged.

[0076] Comparative Example 4

[0077] The comparative example uses commercially available sprayable polyurea material (Suzhou Ruigu Flooring Polyurea) as a comparison.

[0078] Comparative Example 5

[0079] This comparative example uses a commercially available polyurethane coating (Huaming Waterproof Two-Component Polyurethane Coating) as a comparison. The preparation method is as follows:

[0080] Test case

[0081] The materials in the examples and test cases were tested according to current standards for surface drying time (GB / T16777-2008), solid content (GB / T16777-2008), tensile strength (GB / T 1040.2-2022), elongation at break (GB / T 1040.2-2022), flexural modulus (GB / T 2567-2021), flexural strength (GB / T 2567-2021), Shore hardness (GB / T 2411-2008), abrasion resistance (1000g / 1000r, CS-10 wheel, GB / T 1768-2006), appearance after immersion in 10% H2SO4 for 30 days (GB / T11547-2008), and appearance after immersion in 10% NaOH for 30 days (GB / T11547-2008). The results are shown in Table 1.

[0082] Table 1

[0083]

[0084] As shown in Table 1, the surface drying time of Examples 1-3 is no more than 30 seconds, which is far superior to the conventional materials in the industry used in Comparative Examples 4 and 5. Meanwhile, the solid content of the embodiments of the present invention is ≥99.0%, with no molding shrinkage defects caused by solvent evaporation. In contrast, the solid content of Comparative Examples 4 and 5 is less than 99%, exhibiting solvent evaporation shrinkage problems, which easily lead to coating cracking and decreased adhesion. This further verifies the application and molding stability of the formulation system of the present invention.

[0085] Examples 1-3 all exhibit tensile strength ≥65MPa, flexural modulus ≥5500MPa, flexural strength ≥88MPa, and Shore hardness D ≥84. Simultaneously, the elongation at break is stably controlled between 5.1% and 6.2%, achieving a precise balance between ultra-high rigidity and controllable toughness, fully meeting the mechanical performance requirements for underground pipeline structural repair. A comparison between Comparative Example 1 and Example 1 shows that the absence of ultra-short chopped glass fibers in the composite rigid filler leads to varying degrees of reduction in the mechanical properties of the materials. A comparison between Comparative Example 2 and Example 1 shows that omitting the horizontal sand mill grinding step in the material preparation process results in uneven mechanical properties and a decrease in overall mechanical performance. This may be because omitting the horizontal sand mill grinding step leads to localized agglomeration of the filler, highlighting the necessity of this step in the entire process. A comparison between Comparative Example 3 and the examples shows that when the amount of composite rigid filler added deviates from the scope of the claims, both the mechanical properties and wear resistance of the material decrease. Compared to the mainstream polyurea material in Comparative Example 4, the tensile strength and flexural modulus of this invention are significantly improved, solving the core problem of insufficient rigidity and inability to achieve structural reinforcement in traditional polyurea materials. Compared to the conventional polyurethane in Comparative Example 5, this invention overcomes the technical bottleneck that ordinary fast-curing polyurethane can only achieve functional repair for seepage prevention and cannot complete structural repair. Furthermore, the wear amount of this invention is at most 13mg, far superior to existing products, meeting the service requirements of long-term media scouring and silt abrasion in underground pipelines, and significantly extending the service life of the repaired pipeline.

[0086] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A two-component polyurethane spraying material, characterized in that, The raw material components include the following parts by weight: Component A isocyanate prepolymer: 42-46 parts of polymethylene polyphenyl polyisocyanate, 54-58 parts of polyethylene adipate diol; Component B polyol complex: 33-40 parts of main polyol, 13-17 parts of modifier, 0.8-1.2 parts of catalyst, 5.3-7.8 parts of functional additives, and 55-65 parts of rigid filler; The mass ratio of the isocyanate prepolymer of component A to the polyol complex of component B is 1:(2.0-2.5), and the equivalent ratio of the isocyanate groups in the isocyanate prepolymer of component A to the hydroxyl groups in the polyol complex of component B is (1.05-1.15):

1.

2. The two-component polyurethane spraying material as described in claim 1, characterized in that, The NCO content in the polymethylene polyphenyl polyisocyanate is 29.5%-30.5%, and it is selected from PAPI and / or MDI; The number-average molecular weight of the poly(ethylene adipate) diol is 1900-2100.

3. The two-component polyurethane spraying material as described in claim 1, characterized in that, The main polyol comprises polybutylene adipate diol and polypropylene glycol in a mass ratio of (2-4):1; The number-average molecular weight of the polybutylene adipate diol is 950-1050; the number-average molecular weight of the polypropylene glycol is 2800-3200.

4. The two-component polyurethane spraying material as described in claim 1, characterized in that, The modifier comprises bisphenol A epoxy resin E-51 and castor oil in a mass ratio of (8-10):(5-7).

5. The two-component polyurethane spraying material as described in claim 1, characterized in that, The catalyst comprises a dibutyltin dilaurate, a bismuth-zinc composite catalyst, and triethylenediamine in a mass ratio of (0.8-1.2):(1.0-1.2):(0.8-1.2).

6. The two-component polyurethane spraying material as described in claim 1, characterized in that, The functional additives include the following components in parts by weight: 1.5-2.5 parts of polymeric dispersant BYK-110, 2.0-3.0 parts of silane coupling agents KH-550 and KH-560 in a mass ratio of 2:(0.5-1.5), 0.5-1.0 parts of non-silicone defoamer BYK-066N and organosilicon defoamer BYK-024 in a mass ratio of 2:(0.5-1.5), and 0.3-0.5 parts of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:(0.5-2).

7. The two-component polyurethane spraying material as described in claim 1, characterized in that, The rigid filler comprises hydrophobic fumed silica, α-phase nano alumina, ultrafine calcium carbonate and ultra-short chopped glass fiber in a mass ratio of (1-3):1:(30-35):(5-7). The hydrophobic fumed silica nanoparticles have a particle size of 50-100 nm and a specific surface area of ​​200±20 m². 2 / g, hydrophobicity ≥40%; The α-phase nano-alumina has a particle size of 80-100 nm and a purity of ≥99.5%. The ultrafine calcium carbonate has a particle size of 1-3 μm and an activation degree of ≥95%. The ultra-short chopped glass fiber is silane-modified alkali-free glass fiber with a length of 0.1-0.3 mm.

8. A method for preparing a two-component polyurethane spraying material according to any one of claims 1-7, characterized in that, Includes the following steps: Preparation of S1 and A components (1) Under a protective atmosphere and at 68-72℃, polymethylene polyphenyl polyisocyanate was added dropwise to the vacuum-dried polyethylene adipate diol and reacted. The reaction was terminated when the NCO content in the reaction system reached 8.0%-9.0%. (2) Cool down to below 40°C, degas under vacuum, filter, and seal with nitrogen to obtain component A; Preparation of components S2 and B (1) Mix the dried rigid filler with 45-55 wt% of the total amount of silane coupling agent and perform dry surface modification; (2) Mix the main polyol and castor oil and vacuum dry them to remove water content ≤0.05wt%. Cool the temperature to 80-90℃ and add bisphenol A epoxy resin E-51 for epoxy modification. Then add the catalyst, remaining silane coupling agent, polymer dispersant, defoamer and antioxidant in sequence to form a uniform mixture system. (3) Cool the mixture to 65-70℃, add the rigid filler modified in step (1) and disperse it at high speed, then transfer it to a horizontal sand mill and grind it to a fineness of ≤20μm; (4) Cool down to below 40°C, degas under vacuum, filter, and seal with nitrogen to obtain component B; S3. Store components A and B in a sealed container at room temperature, dry and protected from light. Mix them on-site according to the specified ratio before construction to obtain a two-component polyurethane spraying material.

9. The method for preparing the two-component polyurethane spraying material as described in claim 8, characterized in that, S1 and S2 control the relative humidity of the production environment to ≤40% throughout the entire process.

10. The application of the two-component polyurethane spraying material according to claims 1-7 in trenchless structural repair of underground pipelines, characterized in that, The underground pipeline network includes concrete drainage pipes, inspection wells, underground integrated pipe corridors, and steel water transmission pipes. The two-component polyurethane spraying material is applied by high-pressure airless spraying equipment with a working pressure ≥20MPa.

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