PCCP pipe bell and spigot joint sealing structure and preparation method thereof

Abstract

The invention discloses a PCCP pipe bell and spigot joint sealing structure and a preparation method thereof.The preparation method includes the steps that a joint is filled with an elastic blocking piece, the joint is divided into a first sub-joint and a second sub-joint which are sequentially arranged from inside to outside, and a first grouting opening communicating with the first sub-joint is reserved; a locking mechanism is adopted to enable the elastic blocking piece to abut against the interior of the joint, mortar is poured into the first sub-joint through the first grouting opening, and the locking mechanism is removed after the mortar does not flow; the second sub-joint is sealed through a sealing mechanism, a second grouting opening is reserved, polyurethane sealant is poured into the second sub-joint through the second grouting opening, and the sealing mechanism is removed after curing; the elastic barrier is basically non-sticky or slightly bonded with the mortar and the polyurethane sealant; the method is suitable for construction in the low-temperature environment, the construction speed is high, meanwhile, the obtained sealing structure can adapt to different stress interferences and different environmental factors, and lasting sealing can be achieved.

Description

Technical Field

[0001] This invention relates to the field of PCCP pipe socket sealing technology, specifically to a PCCP pipe socket joint sealing structure and its preparation method. Background Technology

[0002] Prestressed concrete cylinder pipe (PCCP) is a composite pipe made of high-strength prestressed steel wire, steel cylinder, concrete, and cement mortar. It combines the rigidity of concrete with the tensile strength of steel, offering significant advantages in large-diameter (e.g., 2-5 meter diameter), high-pressure, and long-distance drainage projects. Currently, PCCP is mainly used in large-scale, important water conveyance projects, such as urban water supply mains and industrial water pipelines, large-scale water diversion projects, power plant circulating water pipelines and pressure tunnels, and large-scale agricultural irrigation water transmission lines.

[0003] The socket joint of a PCCP pipe is a critical connection point and also the weakest point in the entire pipeline sealing system. Its sealing performance directly affects the overall performance of the pipeline. Once damaged, moisture, sulfates, chloride ions, and other substances can enter and corrode the prestressed steel wire. Steel wire corrosion is the most significant and destructive failure mode of PCCP. Once the steel wire breaks, the prestress is lost, and the pipe body may burst.

[0004] Currently, the joint grooves formed at the joints after PCCP socket installation are usually filled and sealed with cement mortar. For example, cement mortar with a compressive strength of 20MPa is mixed with water on site and then filled. However, the quality and amount of water added are uncontrollable, causing cracking during the mortar curing process. Moreover, during the service of the pipeline, phenomena such as water hammer and geological subsidence may be difficult to avoid. In desert, Gobi and arid areas, there is a lot of wind and sand, large temperature difference, and low humidity. In autumn, the highest daytime temperature is around 20℃, and the nighttime temperature often drops below -5℃. The unique application conditions caused by the superposition of various factors place higher demands on the workability of the joint groove sealing system and the durability of the filling and sealing materials at the joint grooves under different stress interferences and environmental factors.

[0005] It should be noted that the information disclosed in the background section above is only for understanding the background of this application. Therefore, the background section of this invention may include background information about the problems or environment of this invention, and is not necessarily a description of the prior art. Thus, the content included in the background section does not constitute an admission of the prior art by the applicant. Summary of the Invention

[0006] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide an improved method for preparing a PCCP pipe socket joint sealing structure that can achieve a durable seal under different stress interferences and environmental factors.

[0007] Furthermore, the PCCP pipe socket joint sealing structure of the present invention can be quickly and easily constructed in low temperature and low humidity environments, and is particularly suitable for areas with large temperature differences and low humidity.

[0008] The present invention also provides a PCCP pipe socket joint sealing structure prepared by the above method.

[0009] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing a sealing structure for a PCCP pipe socket joint, the method comprising: Fill the joint with an elastic barrier to divide the joint into a first sub-joint and a second sub-joint arranged sequentially from the inside to the outside, and reserve a first grouting port that communicates with the first sub-joint. A locking mechanism is used to hold the elastic barrier in the joint. Mortar is injected into the first sub-joint through the first grouting port. The locking mechanism is removed after the mortar stops flowing. The second sub-joint is sealed by a sealing mechanism and a second grouting port is reserved. Polyurethane sealant is injected into the second sub-joint through the second grouting port. After curing, the sealing mechanism is removed. According to the test method of JC / T 942-2022, the peel strength between the elastic barrier and the mortar, and between the elastic barrier and the polyurethane sealant, is less than or equal to 0.1 N / mm.

[0010] In some embodiments of the present invention, the material of the elastic barrier is a polyolefin material.

[0011] Furthermore, the polyolefin material comprises one, two or more combinations selected from polyethylene, polystyrene, ethylene-propylene copolymer, ethylene-butene copolymer, and propylene-butene copolymer.

[0012] In some embodiments of the present invention, the thickness of the elastic barrier in the radial direction of the PCCP pipe is 0.05-0.2 times the height of the joint in the radial direction of the PCCP pipe.

[0013] In some embodiments of the present invention, the elastic barrier is interference-fitted with the inner wall of the joint.

[0014] In some embodiments of the present invention, the ratio of the height of the first sub-joint along the radial direction of the PCCP pipe to the height of the second sub-joint along the radial direction of the PCCP pipe is 1:0.2-1.

[0015] In some embodiments of the present invention, the mortar is a polymer cement waterproof mortar that meets product standard JC / T984.

[0016] In some embodiments of the present invention, the preparation method further includes: before injecting the polyurethane sealant, drying the surface of the elastic barrier and the surface of the second sub-joint respectively, and controlling the moisture content to be less than or equal to 6%.

[0017] In some embodiments of the present invention, the first grouting port is reserved on the top of the elastic barrier, and the second grouting port is reserved on the top of the sealing mechanism.

[0018] In some embodiments of the present invention, the locking mechanism includes a rubber band that can hold the elastic barrier against the seam.

[0019] In some embodiments of the present invention, the sealing mechanism includes an isolation membrane and a rubber band, wherein the isolation membrane is disposed inside the rubber band and faces the second sub-joint.

[0020] In some embodiments of the present invention, the polyurethane sealant comprises component A and component B; The raw materials for component A include polyols, a first bio-based polyol composition, and polyisocyanates; The raw materials for component B include chain extenders, crosslinking agents, a second bio-based polyol composition, fillers, and catalysts; The first bio-based polyol composition and the second bio-based polyol composition each independently comprise a first unit and a second unit; The first unit comprises a bio-based polyol, which is prepared by the following method: epoxidation of castor oil with peroxy acid to generate a first intermediate; epoxidation ring-opening reaction of the first intermediate with the compound shown in formula (I) to generate a second intermediate; and esterification reaction of the second intermediate with the compound shown in formula (II) to generate the bio-based polyol. In equation (Ⅰ), R1 is selected from C 2-6 Alkylene; In equation (II), R2 and R3 are independently selected from C. 1-3 Alkylene; R4 is selected from C 1-3 alkyl or hydroxy substituted C 1-3 alkyl; The second unit comprises the compound shown in formula (Ⅲ); In equation (Ⅲ), R5, R6, and R7 are independently selected from C. 2-10 Alkylene, C-type double bond interruption 2-10 alkylene and epoxy group interrupted C 2-10 Alkylene, R8, R9, R 10 Selected independently from C 2-10 Alkyl, alkenyl C 2-10 Alkyl, epoxy C 2-10 Alkyl groups, C-shaped double bonds 2-10 Alkyl and epoxy groups with interrupted C 2-10 alkyl.

[0021] Further, by weight, the raw materials of component A include: 70-80 parts of polyol, 5-10 parts of the first bio-based polyol composition, and 10-20 parts of polyisocyanate.

[0022] Further, by weight, the raw materials of component B contain: 5-10 parts of chain extender, 60-70 parts of crosslinking agent, 5-10 parts of second bio-based polyol composition, 10-20 parts of filler, and 0.1-0.5 parts of catalyst.

[0023] Furthermore, the mass ratio of component A to component B is 1:0.8-1.2.

[0024] In some embodiments of the present invention, in component A, the polyol is a polyether diol and / or a polyether triol. Further, the average molecular weight of the polyether diol is 2000-6000, and the average molecular weight of the polyether triol is 3000-8000.

[0025] In some embodiments of the present invention, the polyisocyanate in component A is a diisocyanate. Further, the diisocyanate comprises one or more combinations selected from toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

[0026] In some embodiments of the present invention, the chain extender in component B comprises a sterically hindered amine chain extender. Further, the sterically hindered amine chain extender comprises one or more combinations selected from dimethylthiotoluene diamine, 4,4'-di(alkylamino)-diphenylmethane, N,N'-dialkylphenyl diamine, 4,4'-di(alkylamino)-dicyclohexylmethane, and polyaspartic acid esters (e.g., which can be prepared by Michael addition reaction of dialkyl maleate with aliphatic primary diamine).

[0027] In some embodiments of the present invention, the crosslinking agent in component B is selected from polyether triols with an average molecular weight of 3000-8000.

[0028] In some embodiments of the present invention, the filler in component B is selected from one or more combinations of calcium carbonate, kaolin, talc, and mica.

[0029] In some embodiments of the present invention, the catalyst in component B is composed of an organobismuth catalyst and an amine catalyst. Further, the organobismuth catalyst comprises bismuth isooctanoate and / or bismuth neodecanoate, and the amine catalyst comprises triethylenediamine and / or dimethylaminoethyl ether. Even further, the mass ratio of the organobismuth catalyst to the amine catalyst is 1:0.5-2.

[0030] In some embodiments of the present invention, the raw materials of component A further include a defoamer, and the amount of defoamer used is 0.1-1 parts.

[0031] In some embodiments of the present invention, the raw materials of component B further include one or more combinations of color paste, dispersant, and defoamer; further, by weight, the raw materials of component B contain 1-5 parts of color paste, 0.1-0.5 parts of dispersant, and 0.1-1 parts of defoamer.

[0032] The color paste, dispersant, and defoamer used in components A and B can all be made from raw materials commonly used in the field, and no specific limitations are made here.

[0033] In some embodiments of the present invention, a method for preparing the above-described polyurethane sealant includes: Preparation of component A: The polyol and the first bio-based polyol composition were dried separately, then mixed with the remaining components and reacted to obtain component A. Preparation of component B: The chain extender, crosslinking agent, second bio-based polyol composition, and filler in component B are mixed and dehydrated. Then, dispersant and defoamer are selectively added, and finally, catalyst is added and mixed to obtain component B.

[0034] In some embodiments of the present invention, during the preparation of component A, the moisture content is controlled to be below 500 ppm after drying.

[0035] In some embodiments of the present invention, the reaction temperature during the preparation of component A is 70-100°C.

[0036] In some embodiments of the present invention, during the preparation of component B, dehydration is controlled to be carried out under vacuum conditions at 100-125°C. Furthermore, the vacuum level is controlled to be maintained below -0.09 MPa.

[0037] In some embodiments of the present invention, the method for preparing the PCCP pipe socket joint sealing structure further includes: after the polyurethane sealant has cured, applying an anti-corrosion coating to the surface of the polyurethane sealant and its adjacent portion.

[0038] Furthermore, the anti-corrosion coating is formed by coating a single-component polyurethane anti-corrosion coating, wherein the raw materials of the single-component polyurethane anti-corrosion coating include a bio-based polyol composition, a polyisocyanate with an NCO group content of greater than or equal to 20%, fillers, anti-sagging agents, composite catalysts, and solvents. The bio-based polyol composition comprises a first unit and a second unit; the first unit comprises a bio-based polyol, which is prepared by the following method: epoxidizing castor oil with peroxy acid to generate a first intermediate; reacting the first intermediate with the compound shown in formula (I) to undergo an epoxidative ring-opening reaction to generate a second intermediate; and reacting the second intermediate with the compound shown in formula (II) to undergo an esterification reaction to generate the bio-based polyol. In equation (Ⅰ), R1 is selected from C 2-6 Alkylene; In equation (II), R2 and R3 are independently selected from C. 1-3 Alkylene; R4 is selected from C 1-3 alkyl or hydroxy substituted C 1-3 alkyl; The second unit comprises the compound shown in formula (Ⅲ); In equation (Ⅲ), R5, R6, and R7 are independently selected from C. 2-10 Alkylene, C-type double bond interruption 2-10 alkylene and epoxy group interrupted C 2-10 Alkylene, R8, R9, R 10 Selected independently from C 2-10 Alkyl, alkenyl C 2-10 Alkyl, epoxy C 2-10 Alkyl groups, C-shaped double bonds 2-10 Alkyl and epoxy groups with interrupted C 2-10 alkyl; The composite catalyst consists of a main catalyst and a co-catalyst; the main catalyst comprises dibutyltin dilaurate and / or stannous octoate, and the co-catalyst comprises N,N-dimethylcyclohexylamine.

[0039] In some embodiments of the present invention, the raw materials of the single-component polyurethane anticorrosive coating, by weight, include 30-50 parts of bio-based polyol, 15-25 parts of polyisocyanate with NCO group content greater than or equal to 20%, 6-10 parts of the compound shown in formula (Ⅲ), 10-20 parts of filler, 2-5 parts of anti-sagging agent, 0.3-1.5 parts of composite catalyst, and 5-20 parts of solvent.

[0040] In some embodiments of the present invention, the mass ratio of the main catalyst to the co-catalyst in the composite catalyst is 2-3:1.

[0041] In some embodiments of the present invention, the filler comprises nano-silica and talc; further, in the filler, the mass ratio of nano-silica to talc is 1:3-5.

[0042] In some embodiments of the present invention, the polyisocyanate is a polymethylene polyphenyl isocyanate and / or a hexamethylene diisocyanate trimer.

[0043] In some embodiments of the present invention, the anti-sagging agent is one or more selected from hydrogenated castor oil, polyamide wax, and fumed silica.

[0044] In some embodiments of the present invention, the solvent is a mixed solvent of anhydrous toluene and ethyl acetate in a mass ratio of 1:1-2.

[0045] In some embodiments of the present invention, during the preparation of the bio-based polyol, the epoxidation reaction is carried out at 40-60°C and / or in the presence of an alkaline substance. Further, the alkaline substance comprises an alkali metal carbonate and / or an alkali metal hydroxide. More further, the mass of the alkaline substance added accounts for 0.01%-0.3% of the mass of the castor oil added, for example, it can be 0.01%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.20%, 0.25%, etc.

[0046] According to some specific aspects of the invention, the alkali metal carbonate includes sodium carbonate and / or potassium carbonate.

[0047] According to some specific aspects of the invention, the alkali metal hydroxide includes sodium hydroxide and / or potassium hydroxide.

[0048] In some embodiments of the present invention, the mass ratio of castor oil to peroxy acid is 6-8:1, for example, it can be 6.0:1, 6.5:1, 7.0:1, 7.5:1, 8:1, etc.

[0049] In some embodiments of the present invention, the peroxyacid comprises trifluoroperacetic acid.

[0050] In some embodiments of the present invention, the epoxy ring-opening reaction is carried out at 120-160°C during the preparation of the bio-based polyol.

[0051] According to some specific aspects of the present invention, the epoxy ring-opening reaction is carried out at 130-150°C during the preparation of the bio-based polyol.

[0052] In some embodiments of the present invention, the epoxy ring-opening reaction is carried out in the presence of a tetraalkyl halogenated amine. Further, the tetraalkyl halogenated amine comprises tetrabutylammonium bromide. Even further, the mass of the added tetraalkyl halogenated amine accounts for 0.5%-4.0% of the mass of the compound shown in formula (I), for example, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.2%, 1.5%, 1.6%, 1.8%, 2.0%, 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, etc.

[0053] In some embodiments of the present invention, the mass ratio of the compound represented by formula (Ⅰ) to the castor oil is controlled to be 1.05-1.25:1.

[0054] In some embodiments of the present invention, in formula (I), R1 is selected from ethylene, propylene, and butylene.

[0055] In some embodiments of the present invention, the esterification reaction is carried out at 120-160°C during the preparation of the bio-based polyol. According to some specific aspects of the present invention, the esterification reaction is carried out at 130-150°C during the preparation of the bio-based polyol.

[0056] In some embodiments of the present invention, the esterification reaction is carried out in the presence of an acid, further comprising trifluoromethanesulfonic acid and / or p-toluenesulfonic acid, and even further comprising 0.1%-2.0% of the total mass of the reaction system.

[0057] In some embodiments of the present invention, the mass ratio of the compound represented by formula (II) to the castor oil is controlled to be 0.5-0.65:1.

[0058] In some embodiments of the present invention, in formula (II), R2 and R3 are independently selected from methylene, ethylene, and propylene, and R4 is selected from methyl, ethyl, propyl, or hydroxylated methyl.

[0059] In some embodiments of the present invention, in formula (III), R5, R6, and R7 are independently selected from propylidene, butylidene, pentylidene, hexylidene, heptylidene, octylidene, pentylidene with double bond break, hexylidene with double bond break, heptylidene with double bond break, octylidene with double bond break, pentylidene with epoxy group break, hexylidene with epoxy group break, heptylidene with epoxy group break, octylidene with epoxy group break, and octylidene with epoxy group break; R8, R9, and R 10 Independently selected from propyl, butyl, pentyl, hexyl, heptyl, octyl, and alkenyl C 3-8 Alkyl, epoxy C 3-8 Alkyl groups, C-shaped double bonds 3-8 Alkyl and epoxy groups with interrupted C 3-8 alkyl.

[0060] In this invention, C 3-8 Alkyl groups include, but are not limited to, propyl, butyl, pentyl, hexyl, heptyl, and octyl.

[0061] In some embodiments of the present invention, the mass ratio of the first unit to the second unit is 1:0.25-0.50.

[0062] In some embodiments of the present invention, the compound represented by formula (I) comprises ethylene glycol.

[0063] In some embodiments of the present invention, the compound represented by formula (II) contains 2,2-dihydroxymethylpropionic acid.

[0064] In some embodiments of the present invention, the second unit comprises epoxidized soybean oil.

[0065] In some embodiments of the present invention, a method for preparing the above-described single-component polyurethane anticorrosive coating includes: The bio-based polyol, the compound shown in formula (III), and the filler were dehydrated respectively, and then the solvent and polyisocyanate were added under the protection of a protective gas and mixed to react. The reaction was stopped when the mass content of NCO was 3%-5%, the system temperature was lowered, and the remaining components were added.

[0066] Furthermore, the bio-based polyol and the compound shown in formula (III) are dehydrated for a period of time (e.g., 2-3 h) under vacuum conditions (vacuum degree is approximately -0.09 to -0.08 MPa) and at a temperature of 100-120 °C.

[0067] Furthermore, the packing is dried and dehydrated at 80-100℃ for a period of time (e.g., 4-6 hours).

[0068] Furthermore, the protective gas may include, but is not limited to, nitrogen and / or inert gases, such as argon and helium.

[0069] Furthermore, the mixed reaction can be carried out at 60-75°C, and can also be carried out under stirring conditions, with a stirring speed of 500-600 rpm.

[0070] Another technical solution provided by the present invention: a PCCP pipe socket joint sealing structure prepared by the above-described method.

[0071] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: Based on the shortcomings of existing PCCP socket joint sealing structures, such as insufficient durability, this invention innovatively provides an improved method for preparing a PCCP pipe socket joint sealing structure. This method uses a combination of two sealing structures: mortar and polyurethane sealant, especially with an elastic barrier component that has very low bonding strength between the two. First, its function as a barrier facilitates the application of mortar and polyurethane sealant. Secondly, its inherent elasticity makes it easy to squeeze into the joint for quick and relatively stable installation; Third, since the bonding strength between it and the mortar and polyurethane sealant on both sides is very small, when the two deform, the force is basically applied at two points, which helps to ensure that the mortar and the adhesive layer do not break (more than three points of force can easily cause the adhesive layer to break). At the same time, the elastic barrier can also provide a buffer margin for deformation, preventing the relatively sharp mortar curing layer from piercing the adhesive layer, thereby improving the durability of the overall sealing structure.

[0072] Furthermore, this invention also provides a polyurethane sealant with good leveling properties, rapid curing, and ultra-low modulus characteristics at low temperatures. When applied to the sealing structure of PCCP pipe socket joints, it addresses the following issues: Firstly, since the PCCP pipe socket joint is an annular groove, the sealant needs to have good fluidity, especially at low temperatures, where the viscosity cannot increase too much, otherwise self-leveling will be difficult to achieve, affecting construction. Secondly, curing is usually slow at low temperatures, which also affects the construction progress. The polyurethane sealant of this invention can achieve rapid curing at low temperatures through formulation design.

[0073] Furthermore, the present invention also provides a single-component polyurethane coating with rapid curing characteristics in low-temperature and low-humidity environments. At the same time, the viscosity of the material increases only slightly at low temperatures, and it can still maintain a suitable viscosity, which facilitates the anti-corrosion construction of pipe joints. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the structure of the spigot and socket joint (i.e., a semi-closed annular groove) formed by connecting two PCCP pipe sections in an embodiment of the present invention. Figure 2 for Figure 1 A partial structural diagram (mainly illustrating the structure of the socket joint). Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 This is a cross-sectional schematic diagram of the spigot and socket joint formed by connecting two PCCP pipe sections in an embodiment of the present invention; Figure 5 In order to be in Figure 4 A schematic diagram showing the addition of elastic barrier elements to the existing structure. Figure 6 In order to be in Figure 5 A schematic diagram showing the mortar pouring process on the basis of the above. Figure 7 In order to be in Figure 6 A schematic diagram showing the polyurethane sealant poured onto the substrate. Figure 8 In order to be in Figure 7 A schematic diagram showing the application of an anti-corrosion coating on the sealant layer and adjacent areas. Figure 9 Photograph of a flexible barrier filling the spigot and socket joint; Figure 10 Photograph of polyurethane sealant being poured; Figure 11 This is a photo of the sealant after it has partially cured (part of the sealing mechanism has been removed). Figure 12 Photos taken after the anti-corrosion coating has been applied; Figure 13 The infrared spectrum of the bio-based polyol prepared in the embodiments of the present invention; Figure 14 This is a constant elongation test diagram of the polyurethane sealant of the present invention, Example 1; Figure 15 The polyurethane sealant of this invention is shown in the constant elongation test diagrams of reference examples 1-3; In the attached diagram, the following labels are used: 10, PCCP pipe; 20, joint; 21, first sub-joint; 22, second sub-joint; 30, elastic barrier; 40, mortar; 50, polyurethane sealant; and 60, anti-corrosion coating. Detailed Implementation

[0075] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are used to illustrate the basic principles, main features, and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are generally the conditions in conventional experiments. Unless otherwise specified in the following embodiments, all raw materials are commercially available or prepared by conventional methods in the art.

[0076] To facilitate understanding of the preparation method of the PCCP pipe socket joint sealing structure of the present invention, the following is combined with... Figures 1 to 3 The structure of PCCP pipes and their socket joints is described. (See also...) Figures 1 to 3 As shown, two PCCP pipes 10 are joined together to form a longer pipe. The required length can be used to join a corresponding number of PCCP pipe segments. Between the two joined PCCP pipes 10, there is a socket joint 20. The socket joint 20 is a semi-closed annular groove with the opening facing outward. This annular groove needs to be sealed to ensure that the fluid flowing inside the pipe, such as water, is not contaminated by external impurities or contaminants.

[0077] Currently, only cement mortar is used for sealing. However, the sealing structure formed by cement mortar is difficult to adapt to complex environmental conditions. For example, during the service of the pipeline, phenomena such as water hammer and geological settlement may be unavoidable. As a result, the two connected PCCP pipe sections may be misaligned, which may lead to cracking of the rigid cement hardened structure. In particular, PCCP pipes are usually buried underground, making it difficult to detect and repair cracks in time. Furthermore, the durability needs to be improved, and the workability at low temperatures is insufficient.

[0078] Based on this, the present invention provides a new method for preparing a sealing structure for a PCCP pipe socket joint, the method comprising: Fill the joint with an elastic barrier to divide the joint into a first sub-joint and a second sub-joint arranged sequentially from the inside out, and reserve a first grouting port that communicates with the first sub-joint. A locking mechanism is used to hold the elastic barrier in the joint. Mortar is injected into the first sub-joint through the first grouting port. The locking mechanism is removed after the mortar stops flowing. The second sub-joint is sealed using a sealing mechanism and a second grouting port is reserved. Polyurethane sealant is injected into the second sub-joint through the second grouting port. After curing, the sealing mechanism is removed. According to the test method of JC / T 942-2022, the peel strength between the elastic barrier and the mortar, and between the elastic barrier and the polyurethane sealant, is less than or equal to 0.1 N / mm.

[0079] This method employs a two-layer sealing structure consisting of mortar and polyurethane sealant, especially with an elastic barrier component that has very low bonding strength with both. Firstly, this barrier component facilitates the application of the mortar and polyurethane sealant. Secondly, its elastic properties allow for quick and stable installation by pressing it into the joint. Thirdly, because of its very low bonding strength with the mortar and polyurethane sealant on both sides, when deformation occurs, the stress is primarily concentrated at both ends, thus preventing breakage of the mortar and sealant layers (stress at more than three ends easily causes sealant layer breakage). Simultaneously, the elastic barrier component provides a buffer against deformation, preventing the relatively sharp cured mortar layer from piercing the sealant layer, thereby improving the overall durability of the sealing structure.

[0080] The following is combined Figures 4 to 12 The preparation process of the novel PCCP pipe socket joint sealing structure described above is further explained.

[0081] See Figure 4 As shown ( Figure 4 Compared to Figure 3 The connection between the two PCCP pipe sections reveals more details. After the two PCCP pipe sections are connected by a socket, there is already a partial sealing area. However, this is different from the technical solution of this invention. Therefore, it will not be described in detail here. This invention is aimed at the joint 20 of the socket, that is, the semi-closed annular groove with the opening facing outward. After the two PCCP pipe sections are connected by a socket, a joint 20 of the socket is formed, that is, the semi-closed annular groove with the opening facing outward. This invention needs to seal this semi-closed annular groove.

[0082] See Figure 5 As shown, an elastic barrier 30 is filled into the joint. The elastic barrier 30 is approximately located in the middle of the joint, and the thickness of the elastic barrier 30 in the radial direction of the PCCP pipe is 0.05-0.2 times the height of the joint in the radial direction of the PCCP pipe (e.g., 0.05, 0.1, 0.12, 0.15, 0.18, etc.). The ratio of the height of the first sub-joint 21 in the radial direction of the PCCP pipe to the height of the second sub-joint 22 in the radial direction of the PCCP pipe is 1:0.2-1 (e.g., 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, etc.). By utilizing the elasticity of the elastic barrier 30, when it is interference-fitted with the inner wall of the joint, it can be stably fitted into the joint unless a large external force is applied. The seam is divided into a first sub-seam 21 and a second sub-seam 22 arranged sequentially from the inside out. The width of the second sub-seam 22 is greater than or equal to the width of the first sub-seam 21. The cross-section of the elastic barrier 30 is not specifically limited and can be square, round, elliptical, etc. When it is fitted into the joint, both sides of it can fit tightly against the inner wall of the joint. The elastic barrier 30 can be made of polyolefin material. Polyolefin material has a different polarity than mortar and polyurethane sealant, resulting in relatively low bonding strength. This allows it to be essentially non-adhesive or only slightly adhesive to the mortar and polyurethane sealant on both sides during barrier application. Thus, when either the mortar or polyurethane sealant undergoes significant deformation, it is difficult for the elastic barrier to pull on the other, ensuring good seal independence. Furthermore, the elastic barrier provides good buffering, absorbing the deformation of either material and reducing negative impacts on the other. In some specific cases, the polyolefin material includes one, two, or more combinations selected from polyethylene, polystyrene, ethylene-propylene copolymer, ethylene-butene copolymer, and propylene-butene copolymer.

[0083] Meanwhile, since the joint is basically a semi-closed annular groove, the elastic barrier is also continuously set along the extension direction of the joint, eventually forming a ring. The elastic barrier is interference-fitted with the inner wall of the joint. Therefore, in order to facilitate grouting, a first grouting port (not shown) communicating with the first sub-joint is reserved at the top of the entire annular elastic barrier. This reserved first grouting port can be formed by the ring not being completely closed, or by removing part of the elastic barrier. There is no specific limitation, as long as a first grouting port that can be used to inject grout is reserved. Furthermore, since the mortar, once injected into the first sub-joint, will exert significant weight and compress the elastic barrier, it may be forced out of the joint. Therefore, to ensure that the elastic barrier remains essentially stationary during mortar injection, a locking mechanism can be installed to firmly anchor it in the joint, keeping its position essentially immobile. The form of the locking mechanism is not specifically limited, as long as it can stably anchor the elastic barrier in the joint. For example, a rubber band can be attached to the outer wall of the elastic barrier, and locking the rubber band will thus hold the elastic barrier in place.

[0084] After the elastic barrier 30 is locked in place, mortar 40 is injected into the first sub-joint 21 through the first grouting port. Once the mortar 40 stops flowing, the locking mechanism is removed. That is, the locking mechanism can be removed after the mortar has initially set and hardened to its strength. At this point, the mortar 40 has stably filled the first sub-joint 21 and can bond firmly to the inner wall of the joint on its own. Even if the locking mechanism is removed, the elastic barrier will not be squeezed out. See the diagram for the structure at this point. Figure 6 and Figure 9 As shown.

[0085] Then, the second sub-joint 22 is sealed using a sealing mechanism and a second grouting port (not shown) is reserved. Polyurethane sealant is injected into the second sub-joint 22 through the second grouting port. After curing, the sealing mechanism is removed. The structure of the sealing mechanism is not specifically limited, as long as it can seal the second sub-joint 22 and facilitate disassembly. For example, the sealing mechanism can include an isolation membrane and a rubber band. The isolation membrane is set inside the rubber band and faces the second sub-joint. The isolation membrane serves as an isolation to prevent the adhesive polyurethane sealant from directly contacting the rubber band. After the sealant cures, it may be difficult to remove the rubber band. By setting the isolation membrane, the rubber band can be prevented from sticking to the sealant layer. The isolation membrane can be made of polyolefin material and can be easily torn off when disassembling. See Figure 10 As shown, after the sealing mechanism seals the second sub-joint, polyurethane sealant can be injected into the second sub-joint through the reserved second grouting port; see [link / reference]. Figure 11 As shown, after the polyurethane sealant has initially cured and formed a stable adhesive layer, the sealing mechanism can be removed. First, remove the rubber wrapping tape, and then tear off the release liner. See the example structure shown below for the final result. Figure 7 As shown, the polyurethane sealant 50 layer is basically flush with the external anti-corrosion layer of the PCCP pipe. Finally, an anti-corrosion coating 60 can be applied to the outside of the polyurethane sealant layer to further protect the polyurethane sealant 50. This anti-corrosion coating 60 can also be applied to the peripheral areas other than the polyurethane sealant layer (e.g.,...). Figure 12 As shown), to ensure its integrity and the stability of the coating structure, forming as... Figure 8 The sealing structure of the PCCP pipe socket joint.

[0086] Furthermore, before injecting the polyurethane sealant, the surfaces of the elastic barrier and the second sub-joint are dried to control the moisture content to be less than or equal to 6%, in order to avoid excessive moisture curing of the polyurethane sealant and to prevent the formation of a large number of pore structures on the surface of the adhesive layer, which would affect the sealing performance of the adhesive layer.

[0087] Furthermore, the mortar is a polymer cement waterproof mortar that meets product standard JC / T984. Its raw materials include a first component and a second component. The first component is cement, fine aggregate, water-reducing agent, etc.; the second component is a high molecular elastic emulsion, such as one or a combination of acrylic rubber emulsion, chloroprene rubber emulsion, and butyl rubber emulsion. The mortar meets the requirements of Table 1 below.

[0088] Table 1

[0089] The mortar only needs to meet the requirements of polymer cement waterproof mortar in product standard JC / T984, and the present invention does not specifically limit its components.

[0090] Furthermore, since prestressed concrete cylinder pipes (PCCPs) are mainly used in large-scale and important water conveyance projects, and in some special regions such as the Xinjiang Uygur Autonomous Region, not only are there large temperature differences between day and night, but the low temperature period is also prolonged. Traditional sealants have obvious defects in low-temperature and low-humidity environments: First, the viscosity increases significantly at low temperatures, resulting in poor fluidity, making grouting difficult and deteriorating construction performance; second, the curing reaction rate decreases significantly at low temperatures, prolonging the surface drying time and actual drying time, affecting construction efficiency and increasing the risk of pollution (for example, slow curing may lead to the adhesion of pollutants such as sand and dust); third, the tensile modulus of the sealant is too high at low temperatures, resulting in excessive rigidity, which easily leads to delamination from the concrete substrate of the PCCP pipe, affecting the sealing effect. In addition, for anti-corrosion coatings, in regions like northern China, the environment is not only low-temperature but also usually low-humidity. For single-component moisture-curing anti-corrosion coatings, the low-temperature and low-humidity environment has a significant impact on the curing speed after on-site spraying, and weather resistance is also important. Similarly, easy low-temperature construction is also required.

[0091] Therefore, there are certain requirements for the performance of sealants and anti-corrosion coatings. To avoid long construction periods (shortening the construction period means reducing costs), they should be easy to apply and avoid harsh operating conditions that lead to inconvenience and easy rework. Thus, the materials should have good storage stability at low temperatures, fast curing speed, and excellent mechanical properties not only at high and normal temperatures, but also at low temperatures. Based on this, the present invention provides a polyurethane sealant with good leveling properties, rapid curing, and ultra-low modulus characteristics at low temperatures. When applied to the sealing structure of PCCP pipe socket joints, it addresses two key issues. First, since PCCP pipe socket joints are annular grooves, the sealant needs good flowability, especially at low temperatures where viscosity cannot increase too much, otherwise self-leveling will be difficult to achieve, affecting construction. Second, curing is typically slow at low temperatures, also impacting construction progress. The polyurethane sealant of this invention achieves rapid curing at low temperatures through formulation design. Simultaneously, a single-component polyurethane coating with rapid curing characteristics at low temperatures and low humidity is also provided. Furthermore, the viscosity of the material increases only slightly at low temperatures, maintaining a suitable viscosity, facilitating corrosion protection construction of pipe joints.

[0092] Furthermore, both the polyurethane sealant and the single-component polyurethane coating of the present invention utilize the specific bio-based polyol composition of the present invention. On one hand, this composition provides a specific bio-based polyol, which uses castor oil as a starting material. The main component of castor oil is fatty acid triglycerides, which not only contain multiple hydroxyl groups but also double bonds and relatively soft aliphatic chains. The present invention converts the double bonds into epoxy groups through an epoxidation reaction, and then performs an epoxy ring-opening reaction with a diol to form multidimensional hydroxyl groups distributed on the aliphatic chains. This is further reacted with a specific dihydroxyalkyl carboxylic acid to form a multidimensional polyol with a certain degree of branching. When used in reaction with isocyanates, it can form a structure with high crosslinking density, improving the coating's density. Moreover, this special structure of the multidimensional polyol has less steric hindrance on its surface, no molecular chain entanglement, and hydroxyl groups distributed on the molecular surface. When reacting with NCO groups, it can also expose the NCO end groups on the molecular surface, reducing moisture content during later curing. Substances such as molecule-chain polyols do not need to break through chain entanglement, allowing for easy contact and reaction, improving reaction kinetics, accelerating the formation of cross-linked networks, and increasing curing speed. In particular, this low degree of branching does not lead to an excessive increase in system viscosity, and the presence of fatty acid chains provides sufficient space for molecular chains to move after the reaction, avoiding the hard and brittle defects that may result from high cross-linking density. This can effectively reduce the tensile modulus of the material at low temperatures and improve durability. On the other hand, the compound of formula (III) of this invention, which is similar in structure to the aforementioned bio-based polyol (e.g., soybean oil), has no molecular chain entanglement compared to polyether diols or polyether triols. The branched structure plays an internal plasticizing role. In particular, the epoxy groups present can slowly participate in the reaction under specific conditions (catalyst conditions and / or temperature conditions), and can further utilize its flexible fatty acid chains to provide intramolecular plasticizing effect, avoiding a single rigid cross-linked structure. At the same time, it balances the relationship between high hardness and elongation at break, impact resistance, and other properties, ensuring excellent comprehensive performance and avoiding the problem of sacrificing one aspect for another.

[0093] The preparation process of the bio-based polyol of the present invention will be further explained below with reference to the specific reaction route: Castor oil undergoes an epoxidation reaction with a peroxy acid (such as trifluoroperacetic acid) to generate the first intermediate; ; The first intermediate undergoes an epoxy ring-opening reaction with the compound shown in formula (I) (e.g., ethylene glycol) to generate the second intermediate; ; In the reaction route, the structure of the second intermediate is only an exemplary structure. On the one hand, depending on the amount of ethylene glycol added, not all epoxy groups are ring-opened. On the other hand, the position where ethylene glycol is attached may also be on the left side. The second intermediate is esterified with the compound shown in formula (II) (for example, 2,2-dimethylolpropionic acid) to generate a bio-based polyol; ; In the reaction route, the structure of the bio-based polyol is only an exemplary structure. On the one hand, depending on the amount of 2,2-dimethylolpropionic acid added, some hydroxyl groups may undergo esterification. Of course, the bio-based polyol may also be a mixture, that is, the number of hydroxyl groups that may undergo esterification in some molecules may not be the same. In the end, a grafted modified product that follows the esterification reaction process is formed, namely, the bio-based polyol.

[0094] Furthermore, the bio-based polyol composition consists of a bio-based polyol and a compound of formula (III), which can be obtained by adding raw materials such as epoxidized soybean oil. Even further, the bio-based polyol and epoxidized soybean oil are compounded at a mass ratio of 1:0.25-0.50.

[0095] Specifically, the polyurethane sealant of the present invention comprises component A and component B; the raw materials of component A include polyol, a first bio-based polyol composition, and polyisocyanate; the raw materials of component B include chain extender, crosslinking agent, second bio-based polyol composition, filler, and catalyst. The first bio-based polyol composition and the second bio-based polyol composition each independently comprise a first unit and a second unit; the first unit comprises a bio-based polyol, which is prepared by the following method: epoxidizing castor oil with peroxy acid to generate a first intermediate; reacting the first intermediate with the compound shown in formula (I) to undergo an epoxidative ring-opening reaction to generate a second intermediate; and reacting the second intermediate with the compound shown in formula (II) to undergo an esterification reaction to generate a bio-based polyol. In equation (Ⅰ), R1 is selected from C 2-6 Alkylene; In equation (II), R2 and R3 are independently selected from C. 1-3 Alkylene; R4 is selected from C 1-3 alkyl or hydroxy substituted C 1-3 alkyl; The second unit includes the compound shown in formula (Ⅲ); In equation (Ⅲ), R5, R6, and R7 are independently selected from C. 2-10 Alkylene, C-type double bond interruption 2-10 alkylene and epoxy group interrupted C 2-10 Alkylene, R8, R9, R 10 Selected independently from C 2-10 Alkyl, alkenyl C 2-10 Alkyl, epoxy C 2-10 Alkyl groups, C-shaped double bonds2-10 Alkyl and epoxy groups with interrupted C 2-10 alkyl.

[0096] Further, by weight, the raw materials of component A include: 70-80 parts of polyol, 5-10 parts of the first bio-based polyol composition, and 10-20 parts of polyisocyanate; the raw materials of component B include: 5-10 parts of chain extender, 60-70 parts of crosslinking agent, 5-10 parts of the second bio-based polyol composition, 10-20 parts of filler, and 0.1-0.5 parts of catalyst; the mass ratio of component A to component B is 1:0.8-1.2.

[0097] Specifically, the raw materials of the single-component polyurethane anticorrosive coating of the present invention include a bio-based polyol composition, a polyisocyanate with an NCO group content of greater than or equal to 20%, fillers, anti-sagging additives, composite catalysts, and solvents. The bio-based polyol composition is the same as the first or second bio-based polyol composition in the polyurethane sealant; The composite catalyst consists of a main catalyst and a co-catalyst; the main catalyst contains dibutyltin dilaurate and / or stannous octoate, and the co-catalyst contains N,N-dimethylcyclohexylamine.

[0098] Furthermore, by weight, the raw materials of the single-component polyurethane anticorrosive coating include 30-50 parts of bio-based polyol, 15-25 parts of polyisocyanate with NCO group content greater than or equal to 20%, 6-10 parts of the compound shown in formula (Ⅲ), 10-20 parts of filler, 2-5 parts of anti-sagging agent, 0.3-1.5 parts of composite catalyst, and 5-20 parts of solvent.

[0099] Furthermore, in the composite catalyst of the single-component polyurethane anticorrosive coating, the crosslinking reaction rate between hydroxyl groups and isocyanates is controlled by the main catalyst, and the co-catalyst synergistically activates the activity of isocyanate groups. The synergistic effect of the two shortens the curing time under low humidity and avoids the coating embrittlement caused by a single high-dose catalyst. Furthermore, the main catalyst preferentially catalyzes the reaction between the hydroxyl groups of the polyether polyol and the -NCO groups of the isocyanate to form urethane bonds, laying the foundation for coating crosslinking. The co-catalyst, as a strongly alkaline catalyst, can directly activate the reactivity of the isocyanate groups, reducing the reaction activation energy. Even under low humidity, it can promote the reaction between -NCO and a small amount of water and the amino groups in the modifier components, compensating for the curing delay caused by insufficient moisture. Preferably, the mass ratio of the main catalyst to the co-catalyst is 2-3:1 to avoid phenomena such as "excessive surface drying and insufficient actual drying," which leads to incomplete crosslinking of the coating and a decrease in mechanical properties.

[0100] Using the specific bio-based polyol composition of this invention as the main component in a single-component polyurethane anticorrosion coating can fully balance the flexibility and impact resistance of the paint film. The long aliphatic chains of castor oil-based polyols exhibit strong flexibility, and the hydroxyl groups are relatively regularly distributed on the molecular chain. The prepared polyurethane molecular chain has a high proportion of flexible segments, resulting in a paint film with significantly better elongation at break and impact strength than ordinary petroleum-based aliphatic polyol systems. When the metal substrate experiences vibration or deformation (such as steel bridges and storage tanks), the paint film is less prone to cracking and peeling, maintaining a continuous and intact anticorrosion barrier, making it particularly suitable for substrates with high deformation rates. It also possesses stable weather resistance and anti-yellowing properties. The aliphatic chains of castor oil-based polyols do not contain aromatic rings, fundamentally avoiding the epoxidation, cracking, and yellowing problems caused by ultraviolet radiation in aromatic polyols. The polyurethane anticorrosion coating prepared with this composition exhibits good gloss and color retention after outdoor exposure, and is not prone to chalking. It can be used for long-term anticorrosion applications such as outdoor steel structures and building exterior walls, with weather resistance comparable to synthetic aliphatic polyester polyols, but at a lower cost. In particular, the single-component polyurethane anti-corrosion coating of the present invention can achieve the following properties in low temperature and low humidity environments: while ensuring good coating density, anti-sagging and mechanical properties, the curing time in low humidity environments is significantly shortened, and the coating storage stability (storage period ≥ 6 months at 25℃) is also guaranteed.

[0101] This invention further investigates the properties of the aforementioned polyurethane sealant and single-component polyurethane coating, and performs corresponding characterization based on specific experiments.

[0102] [Bio-based polyol compositions and their preparation]: The bio-based polyol composition comprises a first unit and a second unit, and the bio-based polyol composition is obtained by mixing the first unit and the second unit; wherein the first unit is a bio-based polyol, the second unit is epoxidized soybean oil, and the mass ratio of bio-based polyol to epoxidized soybean oil is 1:0.25. Bio-based polyols are prepared by the following method: Castor oil (140g), perfluoroacetic acid (20g), and sodium carbonate (0.28g) were weighed and added to a three-necked flask equipped with a reflux condenser and stirrer. The mixture was heated to 45°C and stirred for 3 hours until the reaction was complete. Then, ethylene glycol (160g) and tetrabutylammonium bromide (3.2g) were added to the three-necked flask, and the mixture was heated to 140°C for 3 hours under nitrogen protection. Next, 2,2-di(hydroxymethyl)propionic acid (80g) and p-toluenesulfonic acid (4g) were added to the three-necked flask, and the reaction was continued for 3 hours. After the reaction, the aqueous phase and organic layer were separated in a separating funnel. The organic layer was washed twice with distilled water and finally dried in a vacuum oven at 70°C to remove excess water, yielding a transparent, pale yellow liquid, which is the bio-based polyol. The obtained bio-based polyol was subjected to infrared spectroscopy testing; see [link to details]. Figure 13 As shown.

[0103] [Implementation Cases and Preparation of Polyurethane Sealants]: Polyurethane sealant implementation case 1: This polyurethane sealant contains component A and component B, with a mass ratio of component A to component B of 1:1; see Table 2 for specific formula raw materials.

[0104] Table 2

[0105] The preparation method of this polyurethane sealant includes: Preparation of component A: The polyether polyol and bio-based polyol composition were dried separately, with the water content controlled below 500 ppm. Then they were mixed with the remaining components and reacted at 80°C for 120 min to obtain component A. Preparation of component B: The chain extender, crosslinking agent, bio-based polyol composition, filler, and color paste in component B were mixed and dehydrated at 110°C under a vacuum of -0.09 MPa for 2 hours. Then, nitrogen gas was introduced to release the vacuum, a dispersant was added, the temperature was lowered to below 75°C, an antifoaming agent and a catalyst were added, and the mixture was stirred to obtain component B.

[0106] When using, simply mix component A and component B according to the mass ratio of the feed ingredients.

[0107] [Reference Case and Preparation of Polyurethane Sealants]: Polyurethane sealant reference case 1: It is basically the same as polyurethane sealant implementation case 1, the only difference is that: neither component A nor component B contains bio-based polyol composition, and the polyether polyol in component A is adjusted to 85.5 parts, and the crosslinking agent in component B is adjusted to 70 parts and the chain extender is adjusted to 11 parts.

[0108] Polyurethane sealant reference case 2: It is basically the same as polyurethane sealant implementation case 1, except that the "bio-based polyol composition" in components A and B is replaced with 6.5 parts of castor oil.

[0109] Polyurethane sealant reference case 3: It is basically the same as polyurethane sealant implementation case 1, except that the "bio-based polyol composition" in components A and B is replaced with 6.5 parts of single epoxidized soybean oil.

[0110] [Performance Testing of Polyurethane Sealants]: The polyurethane sealant implementation case 1 and the polyurethane sealant obtained by referring to cases 1-3 were subjected to the following performance tests, and the test results are shown in Table 3.

[0111] Table 3

[0112] Note: The test methods for each indicator refer to JC / T 482-2022. The viscosity at 23℃ is the viscosity measured by a rotational viscometer after mixing components A and B at 200 rpm for 5 minutes at 23℃. The viscosity at -5℃ is the viscosity measured by a rotational viscometer after placing components A and B at -5℃ for 2 hours, immediately mixing them (stirring at 200 rpm) for 5 minutes. The test method for the elongation adhesion at 23℃ is to prepare samples according to the method in JC / T 482-2022, and then observe the elongation adhesion after placing them at 23℃ for 24 hours. The test method for the elongation adhesion at -30℃ is to prepare samples according to the method in JC / T 482-2022, and then observe the elongation adhesion after placing them in a -30℃ refrigerator for 24 hours.

[0113] See Figure 14 As shown, this is a constant elongation test diagram of polyurethane sealant implementation case 1. Figure 15 The tensile test diagrams of the polyurethane sealant in Examples 1-3 show that the polyurethane sealant of the present invention maintains the integrity of the coating after being held under tension for a long time, while the polyurethane sealant in Examples 1-3 all showed varying degrees of fracture.

[0114] [Implementation Case and Preparation of Single-Component Polyurethane Anticorrosion Coatings]: Implementation Case 1 of Single-Component Polyurethane Anticorrosive Coating: By weight, the raw materials of this single-component polyurethane anticorrosive coating include 50 parts of the bio-based polyol composition prepared according to the above [Bio-based Polyol Composition and its Preparation], 25 parts of polymethylene polyphenyl isocyanate (PAPI, purchased from Shanghai McLean Biochemical Technology Co., Ltd.), 16 parts of filler, 2 parts of anti-sagging agent, 1 part of composite catalyst, 1 part of defoamer (BYK-054, purchased from BYK Chemical), and 5 parts of solvent; The filler is composed of nano-silica (purchased from Hubei Huifu Nanomaterials Co., Ltd., grade HB-701) and talc powder (purchased from Quanzhou Xufeng Powder Raw Materials Co., Ltd., grade XFH-818-F1) in a mass ratio of 1:5. The composite catalyst is composed of dibutyltin dilaurate and N,N-dimethylcyclohexylamine in a mass ratio of 2:1. The solvent is composed of anhydrous toluene and ethyl acetate in a mass ratio of 1:1.

[0115] The preparation method of this one-component polyurethane anti-corrosion coating includes: Weigh each raw material according to the above formula, and then dehydrate the bio-based polyol composition under vacuum conditions (vacuum degree is about -0.08MPa) at a temperature of 110°C for 3 hours; The packing material was dried at 90℃ for 6 hours to remove water. Under nitrogen protection, dehydrated bio-based polyol composition and solvent were added to the reaction vessel and stirred. Dehydrated filler was added under stirring conditions. The temperature was raised to 55±5℃ and stirred at 1000rpm for 60min to obtain a mixed slurry. Polymethylene polyphenyl isocyanate was added to the mixed slurry and the reaction was controlled at 65±5℃. When the NCO content was stabilized at about 5% by infrared detection, the reaction was stopped, the temperature was lowered to 40℃, the remaining components were added, mixed, and degassed to obtain a single-component polyurethane anti-corrosion coating.

[0116] [Reference Case and Preparation of One-Component Polyurethane Anticorrosion Coatings]: Reference Case 1 for Single-Component Polyurethane Anticorrosion Coating: It is basically the same as Implementation Case 1 for Single-Component Polyurethane Anticorrosion Coating, except that the bio-based polyol composition is replaced with the same amount of "polyether polyol composed of DL-2000D (Lanxing Dongda) and MN-3050DF (Lanxing Dongda) in a mass ratio of 4:1".

[0117] Reference Case 2 for Single-Component Polyurethane Anticorrosive Coating: Basically the same as Implementation Case 1 for Single-Component Polyurethane Anticorrosive Coating, except that the "bio-based polyol composition" is replaced with an equal amount of "single modified castor oil". The modified castor oil is prepared using the same method as the bio-based polyol in [Bio-based Polyol Composition and its Preparation], but the preparation process only proceeds to the epoxy ring-opening reaction and does not proceed to the subsequent esterification reaction.

[0118] [Performance Testing of Single-Component Polyurethane Anticorrosion Coatings]: The following performance tests were conducted on the single-component polyurethane anti-corrosion coatings obtained in Implementation Case 1 and Case 1-2, respectively. The test results are shown in Table 4. The tests were conducted in accordance with GB / T 19250-2013 "Polyurethane Waterproof Coatings".

[0119] Table 4

[0120] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0121] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for preparing a sealing structure for a PCCP pipe socket joint, characterized in that, The preparation method includes: Fill the joint with an elastic barrier to divide the joint into a first sub-joint and a second sub-joint arranged sequentially from the inside to the outside, and reserve a first grouting port that communicates with the first sub-joint. A locking mechanism is used to hold the elastic barrier in the joint. Mortar is injected into the first sub-joint through the first grouting port. The locking mechanism is removed after the mortar stops flowing. The second sub-joint is sealed by a sealing mechanism and a second grouting port is reserved. Polyurethane sealant is injected into the second sub-joint through the second grouting port. After curing, the sealing mechanism is removed. According to the test method of JC / T 942-2022, the peel strength between the elastic barrier and the mortar, and between the elastic barrier and the polyurethane sealant, is less than or equal to 0.1 N / mm.

2. The method for preparing the PCCP pipe socket joint sealing structure according to claim 1, characterized in that, The material of the elastic barrier is polyolefin.

3. The method for preparing the PCCP pipe socket joint sealing structure according to claim 2, characterized in that, The polyolefin material comprises one, two or more of the following: polyethylene, polystyrene, ethylene-propylene copolymer, ethylene-butene copolymer, and propylene-butene copolymer.

4. The method for preparing the PCCP pipe socket joint sealing structure according to claim 1, characterized in that, The thickness of the elastic barrier in the radial direction of the PCCP pipe is 0.05-0.2 times the height of the joint in the radial direction of the PCCP pipe; and / or, the elastic barrier is interference-fitted with the inner wall of the joint.

5. The method for preparing the PCCP pipe socket joint sealing structure according to claim 1, characterized in that, The ratio of the height of the first sub-joint along the radial direction of the PCCP pipe to the height of the second sub-joint along the radial direction of the PCCP pipe is 1:0.2-1; and / or, the mortar is a polymer cement waterproof mortar that meets product standard JC / T984.

6. The method for preparing the PCCP pipe socket joint sealing structure according to claim 1, characterized in that, The preparation method further includes: before injecting the polyurethane sealant, drying the surface of the elastic barrier and the surface of the second sub-joint respectively, controlling the moisture content to be less than or equal to 6%; and / or, the first grouting port is reserved at the top of the elastic barrier and the second grouting port is reserved at the top of the sealing mechanism.

7. The method for preparing the PCCP pipe socket joint sealing structure according to claim 1, characterized in that, The locking mechanism includes a rubber band that can hold the elastic barrier against the seam; and / or, the sealing mechanism includes a release membrane and a rubber band, the release membrane being disposed inside the rubber band and facing the second sub-seam.

8. The method for preparing the PCCP pipe socket joint sealing structure according to claim 1, characterized in that, The polyurethane sealant comprises component A and component B; The raw materials for component A include polyols, a first bio-based polyol composition, and polyisocyanates; The raw materials for component B include chain extenders, crosslinking agents, a second bio-based polyol composition, fillers, and catalysts; The first bio-based polyol composition and the second bio-based polyol composition each independently comprise a first unit and a second unit; The first unit comprises a bio-based polyol, which is prepared by the following method: epoxidizing castor oil with peroxy acid to generate a first intermediate; and reacting the first intermediate with the compound shown in formula (I) to generate a second intermediate. The second intermediate is subjected to an esterification reaction with the compound shown in formula (II) to generate the bio-based polyol; In equation (Ⅰ), R1 is selected from C 2-6 Alkylene; In equation (II), R2 and R3 are independently selected from C. 1-3 Alkylene; R4 is selected from C 1-3 alkyl or hydroxy substituted C 1-3 alkyl; The second unit comprises the compound shown in formula (Ⅲ); In equation (Ⅲ), R5, R6, and R7 are independently selected from C. 2-10 Alkylene, C-type double bond interruption 2-10 alkylene and epoxy group interrupted C 2-10 Alkylene, R8, R9, R 10 Selected independently from C 2-10 Alkyl, alkenyl C 2-10 Alkyl, epoxy C 2-10 Alkyl groups, C-shaped double bonds 2-10 Alkyl and epoxy groups with discontinuous C 2-10 alkyl.

9. The method for preparing the PCCP pipe socket joint sealing structure according to claim 8, characterized in that, By weight, the raw materials of component A include: 70-80 parts of polyol, 5-10 parts of the first bio-based polyol composition, and 10-20 parts of polyisocyanate. And / or, By weight, the raw materials of component B contain: 5-10 parts chain extender, 60-70 parts crosslinking agent, 5-10 parts second bio-based polyol composition, 10-20 parts filler, and 0.1-0.5 parts catalyst; and / or, The mass ratio of component A to component B is 1:0.8-1.

2.

10. The method for preparing the PCCP pipe socket joint sealing structure according to claim 8, characterized in that, In component A, the polyol is a polyether diol and / or a polyether triol; further, the average molecular weight of the polyether diol is 2000-6000, and the average molecular weight of the polyether triol is 3000-8000; and / or, In component A, the polyisocyanate is a diisocyanate; further, the diisocyanate comprises one or more combinations selected from toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; and / or, In component B, the chain extender comprises a sterically hindered amine chain extender, and further, the sterically hindered amine chain extender comprises one or more combinations selected from dimethylthiotoluene diamine, 4,4'-di(alkylamino)-diphenylmethane, N,N'-dialkylphenyldiamine, 4,4'-di(alkylamino)-dicyclohexylmethane, and polyaspartic acid ester; and / or, In component B, the crosslinking agent is selected from polyether triols with an average molecular weight of 3000-8000; and / or, In component B, the filler is selected from one or more combinations of calcium carbonate, kaolin, talc, and mica powder; and / or, In component B, the catalyst is composed of an organic bismuth catalyst and an amine catalyst. Further, the organic bismuth catalyst comprises bismuth isooctanoate and / or bismuth neodecanoate, and the amine catalyst comprises triethylenediamine and / or dimethylaminoethyl ether. Even further, the mass ratio of the organic bismuth catalyst to the amine catalyst is 1:0.5-2.

11. The method for preparing the PCCP pipe socket joint sealing structure according to claim 1, characterized in that, The preparation method further includes: after the polyurethane sealant has cured, applying an anti-corrosion coating to the surface of the polyurethane sealant and its adjacent portions.

12. The method for preparing the PCCP pipe socket joint sealing structure according to claim 11, characterized in that, The anti-corrosion coating is formed by coating a single-component polyurethane anti-corrosion coating. The raw materials of the single-component polyurethane anti-corrosion coating include a bio-based polyol composition, a polyisocyanate with an NCO group content of greater than or equal to 20%, fillers, anti-sagging agents, composite catalysts, and solvents. The bio-based polyol composition comprises a first unit and a second unit; the first unit comprises a bio-based polyol, which is prepared by the following method: epoxidizing castor oil with peroxy acid to generate a first intermediate; and reacting the first intermediate with the compound shown in formula (I) to generate a second intermediate. The second intermediate is subjected to an esterification reaction with the compound shown in formula (II) to generate the bio-based polyol; In equation (Ⅰ), R1 is selected from C 2-6 Alkylene; In equation (II), R2 and R3 are independently selected from C. 1-3 Alkylene; R4 is selected from C 1-3 alkyl or hydroxy substituted C 1-3 alkyl; The second unit comprises the compound shown in formula (Ⅲ); In equation (Ⅲ), R5, R6, and R7 are independently selected from C. 2-10 Alkylene, C-type double bond interruption 2-10 alkylene and epoxy group interrupted C 2-10 Alkylene, R8, R9, R 10 Selected independently from C 2-10 Alkyl, alkenyl C 2-10 Alkyl, epoxy C 2-10 Alkyl groups, C-shaped double bonds 2-10 Alkyl and epoxy groups with discontinuous C 2-10 alkyl; The composite catalyst consists of a main catalyst and a co-catalyst; the main catalyst comprises dibutyltin dilaurate and / or stannous octoate, and the co-catalyst comprises N,N-dimethylcyclohexylamine.

13. The method for preparing the PCCP pipe socket joint sealing structure according to claim 12, characterized in that, By weight, the raw materials of the single-component polyurethane anticorrosive coating include 30-50 parts of bio-based polyol, 15-25 parts of polyisocyanate with NCO group content greater than or equal to 20%, 6-10 parts of the compound shown in formula (Ⅲ), 10-20 parts of filler, 2-5 parts of anti-sagging agent, 0.3-1.5 parts of composite catalyst, and 5-20 parts of solvent.

14. The method for preparing the PCCP pipe socket joint sealing structure according to claim 12, characterized in that, In the composite catalyst, the mass ratio of the main catalyst to the co-catalyst is 2-3:1; and / or, The filler comprises nano-silica and talc; further, the mass ratio of the nano-silica to the talc in the filler is 1:3-5; and / or, The polyisocyanate is a trimer of polymethylene polyphenyl isocyanate and / or hexamethylene diisocyanate; and / or The anti-sagging agent is selected from one or more combinations of hydrogenated castor oil, polyamide wax, and fumed silica; and / or The solvent is a mixture of anhydrous toluene and ethyl acetate in a mass ratio of 1:1-2.

15. The method for preparing the PCCP pipe socket joint sealing structure according to claim 8 or 12, characterized in that, In the preparation of the bio-based polyol, the epoxidation reaction is carried out at 40-60°C and / or in the presence of an alkaline substance, wherein the alkaline substance comprises an alkali metal carbonate and / or an alkali metal hydroxide. Furthermore, the alkali metal carbonate includes sodium carbonate and / or potassium carbonate, and the alkali metal hydroxide includes sodium hydroxide and / or potassium hydroxide; Furthermore, the alkaline substance is added at a mass ratio of 0.01% to 0.3% of the castor oil. And / or, The mass ratio of castor oil to peroxyacid is 6-8:1; and / or, The peroxyacid includes trifluoroperacetic acid.

16. The method for preparing the PCCP pipe socket joint sealing structure according to claim 8 or 12, characterized in that, In the preparation of the bio-based polyol, the epoxy ring-opening reaction is carried out at 120-160°C; and / or, The epoxy ring-opening reaction is carried out in the presence of a tetraalkyl halogenated amine, further comprising tetrabutylammonium bromide, and even further, the added mass of the tetraalkyl halogenated amine is 0.5%-4.0% of the added mass of the compound shown in formula (I); and / or, The mass ratio of the compound represented by formula (I) to the castor oil is controlled to be 1.05-1.25:1; and / or, In formula (Ⅰ), R1 is selected from ethylene, propylene, and butylene.

17. The method for preparing the PCCP pipe socket joint sealing structure according to claim 8 or 12, characterized in that, In the preparation of the bio-based polyol, the esterification reaction is carried out at 120-160°C; and / or, The esterification reaction is carried out in the presence of an acid, further comprising trifluoromethanesulfonic acid and / or p-toluenesulfonic acid; and even further, the acid is added at a mass of 0.1%-2.0% of the total mass of the reaction system; and / or, The mass ratio of the compound represented by formula (II) to the castor oil is controlled to be 0.5-0.65:1; and / or, In formula (II), R2 and R3 are independently selected from methylene, ethylene, and propylene, and R4 is selected from methyl, ethyl, propyl, or hydroxylated methyl.

18. The method for preparing the PCCP pipe socket joint sealing structure according to claim 8 or 12, characterized in that, In formula (Ⅲ), R5, R6, and R7 are independently selected from propylidene, butylidene, pentylidene, hexylidene, heptylidene, octylidene, pentylidene with double bond break, hexylidene with double bond break, heptylidene with double bond break, octylidene with double bond break, pentylidene with epoxy group break, hexylidene with epoxy group break, heptylidene with epoxy group break, and octylidene with epoxy group break; R8, R9, and R 10 Independently selected from propyl, butyl, pentyl, hexyl, heptyl, octyl, and alkenyl C 3-8 Alkyl, epoxy C 3-8 Alkyl groups, C-shaped double bonds 3-8 Alkyl and epoxy groups with discontinuous C 3-8 alkyl.

19. The method for preparing the PCCP pipe socket joint sealing structure according to claim 8 or 12, characterized in that, The mass ratio of the first unit to the second unit is 1:0.25-0.50; and / or, the compound represented by formula (I) contains ethylene glycol; and / or, the compound represented by formula (II) contains 2,2-dimethylolpropionic acid; and / or, the second unit contains epoxidized soybean oil.

20. A PCCP pipe socket joint sealing structure manufactured by the preparation method of the PCCP pipe socket joint sealing structure according to any one of claims 1-19.

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