A special repair adhesive for salt pond covering membranes, its preparation method and its application

Abstract

This invention provides a special repair adhesive for saltwater pond covering membranes, its preparation method, and its application, belonging to the field of saltwater pond covering membrane repair. The special repair adhesive for saltwater pond covering membranes comprises, from top to bottom, a PVC substrate, an adhesive layer, and a release film layer. The preparation method of the special repair adhesive for saltwater pond covering membranes includes the following steps: preparing a substrate reinforcement phase, preparing a PVC substrate, and composite molding. The special repair adhesive for saltwater pond covering membranes of this invention can meet the long-term use requirements of the harsh environment of saltwater ponds, has good compatibility with PVC covering membranes in saltwater ponds, and provides good adhesion and durability to PVC covering membranes. Simultaneously, the bonding performance between the substrate and the adhesive is good, the interface bonding is not prone to failure, and the adhesive has good durability, maintaining good bonding and repair performance for a long time in the harsh environment of saltwater ponds.

Description

Technical Field

[0001] This invention relates to the field of salt pond covering membrane repair, and in particular to a special repair adhesive for salt pond covering membranes, its preparation method, and its application. Background Technology

[0002] In the process of evaporating seawater or salt lake brine, the evaporation crystallization tank is the core production unit. Seawater or salt lake brine needs to be evaporated and crystallized in the evaporation crystallization tank for a long time. During this process, a special covering film is usually laid on the surface of the liquid in the evaporation crystallization tank. Its main functions are: (1) to maintain the water temperature in the evaporation crystallization tank, reduce water temperature fluctuations, and increase the crystallization rate; (2) to isolate foreign objects such as wind and sand and bird droppings in the external environment, prevent raw salt pollution, and improve the quality of salt production; (3) to stabilize the crystallization environment and reduce the brine concentration fluctuations caused by weather changes (such as rain and strong winds).

[0003] Currently, the covering membranes used in evaporation crystallization tanks are mainly made of PVC. However, in actual use, PVC covering membranes are easily damaged and cracked due to factors such as external environment, high humidity and salt spray, and diurnal temperature differences. Once the PVC covering membrane is damaged, its heat preservation and anti-fouling functions are greatly reduced. If it is not repaired in time, small tears will quickly expand, causing the entire PVC covering membrane to fail, resulting in huge economic losses.

[0004] For damage to the PVC covering membrane in crystallization ponds, general-purpose adhesives are typically used to repair the damaged areas. However, the adhesives are not well-matched with the PVC covering membranes, resulting in poor adhesion and durability in outdoor, high-humidity, and salt-spray environments. Furthermore, the adhesives can negatively impact the PVC covering membranes, accelerating the aging of the membrane material around the damaged area.

[0005] In existing technologies, adhesive tape can be used to repair damaged membrane materials. However, for PVC covering membranes in evaporation crystallization ponds, conventional adhesive tape is difficult to meet the long-term use requirements under the harsh environment of salt ponds. This is mainly because: the bonding performance between the adhesive substrate and the adhesive is poor, and the interface bonding between the two is prone to failure under the high temperature, salt spray, and temperature change conditions faced by the salt pond covering membrane; at the same time, there are also adverse effects between the adhesive substrate and the adhesive, resulting in poor durability of the adhesive tape, which cannot maintain good adhesion and repair performance for a long time in the extreme environment of evaporation crystallization ponds used for salt production.

[0006] Based on this, a special repair adhesive for salt pond covering membranes is provided, which can meet the long-term use requirements of the harsh environment of salt ponds, has good compatibility with salt pond PVC covering membranes, and has good adhesion effect and adhesion durability to PVC covering membranes; at the same time, the adhesive substrate and adhesive have good bonding performance, the interface bonding is not easy to fail, and the adhesive has good durability, which can maintain good bonding and repair performance for a long time in the harsh environment of salt ponds, which has important technical significance and research value. Summary of the Invention

[0007] To address the technical problems existing in the prior art, this invention provides a special repair adhesive for salt pond covering membranes, which can meet the long-term use requirements in the harsh environment of salt ponds, has good compatibility with salt pond PVC covering membranes, and has good adhesion effect and adhesion durability to PVC covering membranes; at the same time, the adhesive substrate and adhesive have good bonding performance, the interface bonding is not easy to fail, and the adhesive has good durability, which can maintain good bonding and repair performance for a long time in the harsh environment of salt ponds.

[0008] The present invention also provides a method for preparing the special repair adhesive for salt pond covering membrane.

[0009] The present invention also provides the application of the special repair adhesive for salt pond covering membrane in the repair of the covering membrane of salt production evaporation crystallization pond.

[0010] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing a special repair adhesive for salt pond covering membranes includes the following steps: preparing a substrate reinforcement phase, preparing a PVC substrate, and composite molding;

[0012] The preparation of the substrate reinforcement phase includes the following steps: a primary reaction and a secondary reaction;

[0013] The method for the primary reaction is as follows: under inert gas protection and in a solvent environment, at a temperature of 48-50°C, isophorone diamine solution is added dropwise to N,N-dimethylformamide solution containing itaconic anhydride, and the reaction is maintained at this temperature to obtain a reaction solution; after cooling and precipitation, the precipitate is collected; the precipitate is washed and dried to obtain the primary reactant.

[0014] The secondary reaction method is as follows: the primary reactant is added to a solvent, heated to 60-65℃, kept at the temperature and dispersed evenly, the pH is adjusted to 6.0±0.1, and then the composite metal hydroxide slurry is added and kept at the temperature to obtain a reaction solution; the reaction solution is precipitated with ethanol solution and the precipitate is collected; the precipitate is washed and dried to obtain the substrate reinforcement phase;

[0015] The composite metal hydroxide slurry contains zinc hydroxide and zirconium hydroxide;

[0016] The method for preparing the PVC substrate is as follows: after mixing polyvinyl chloride resin, substrate reinforcing phase and additives, the mixture is kneaded and calendered into a film to obtain a PVC substrate with a thickness of 0.1-0.3 mm.

[0017] The composite molding method involves coating an acrylic adhesive onto the release surface of a release film to obtain a release film layer with an adhesive layer; then laminating the release film layer with the adhesive layer to the smooth surface of a PVC substrate to obtain a special repair adhesive for salt pond covering membranes.

[0018] Preferably, in the primary reaction, the dropping time of the isophorone diamine solution is controlled to be 50-70 min;

[0019] The heat preservation reaction time is 5-6 hours.

[0020] Preferably, in the primary reaction, the molar ratio of itaconic anhydride to isophorone diamine is 2-2.05:1;

[0021] The isophorone diamine solution is an N,N-dimethylformamide solution of isophorone diamine with a concentration of 30-32 wt%.

[0022] Preferably, in the secondary reaction, the heat preservation reaction time after adding the composite metal hydroxide slurry is 5-6 hours;

[0023] During the heat preservation reaction, the pH of the material is controlled within the range of 5.8-6.2.

[0024] Preferably, in the secondary reaction, the composite metal hydroxide slurry is an N,N-dimethylformamide dispersion containing zinc hydroxide and zirconium hydroxide, with a zinc hydroxide concentration of 9-9.5 wt% and a zirconium hydroxide concentration of 1.9-2.3 wt%.

[0025] The weight ratio of the primary reactant to the composite metal hydroxide slurry is 1:1.7-1.9.

[0026] Furthermore, in the preparation of the PVC substrate, the additives include: plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide.

[0027] Preferably, the weight ratio of polyvinyl chloride resin, substrate reinforcing phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide is 100-105:4.5-5.5:28-32:5-6:0.3-0.4:0.3-0.4:0.8-0.9:0.4-0.5:0.8-1:11-13:4-5.

[0028] Furthermore, in the composite molding process, the acrylate adhesive is obtained by adding acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 to ethyl acetate, adjusting the solid content to 30-35 wt%, and mixing them evenly.

[0029] After applying an acrylic adhesive to the release surface of the release film, the adhesive layer thickness is adjusted to 25-35 μm after drying to obtain a release film layer with an adhesive layer.

[0030] Preferably, in the acrylate adhesive, the weight ratio of acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 is 100-105:3-4:0.6-0.8:0.5-0.6.

[0031] The room temperature viscosity of acrylic pressure-sensitive adhesive is 18000-20000 mPa·s, and the hydroxyl value is 20-30 mgKOH / g.

[0032] A special repair adhesive for salt pond covering membranes prepared by the aforementioned method.

[0033] An application of the aforementioned special repair adhesive for salt pond covering membranes in the repair of damaged covering membranes in salt production evaporation and crystallization ponds.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) The preparation method of the salt pond covering membrane special repair adhesive of the present invention introduces a zinc zirconium bimetallic / itaconic isophorone diamine diamide acid complex into the PVC substrate. The zinc and zirconium metal coordination centers introduced are used as subsequent binding sites with the adhesive layer, changing the original physical adsorption of the PVC substrate and the adhesive layer to chemical anchoring. This effectively improves the bonding performance between the PVC substrate and the adhesive layer, and improves the peel strength and environmental aging resistance of the adhesive layer. At the same time, the interaction between the organic ligand part of the reinforcing phase and the PVC molecular chain stabilizes the PVC network structure and inhibits the migration of plasticizers. The introduction of the substrate reinforcing phase improves the tensile strength, elongation at break, thermal stability and hydrophobicity of the PVC substrate.

[0036] Furthermore, the introduction of the substrate reinforcement phase can also avoid adverse interactions between the adhesive and the PVC substrate. Through the interaction between the zinc and zirconium metal coordination centers and their organic ligands introduced into the substrate reinforcement phase and the PVC molecular chains, the PVC molecular network is stabilized, improving the durability of the adhesive. The alicyclic structure introduced by isophorone diamine in the substrate reinforcement phase provides hydrophobicity, effectively isolating moisture from penetrating the PVC substrate in high-humidity environments, thus improving the adhesive's water resistance and resistance to high-humidity environments. Additionally, the zinc and zirconium metal coordination centers introduced into the PVC substrate surface by the substrate reinforcement phase uniformly disperse the bonding stress between the PVC substrate and the adhesive, preventing interface cracking caused by stress concentration, improving the adhesion durability and stability of the adhesive to the PVC cover film, and achieving a stable and durable interfacial bond with the PVC cover film.

[0037] The aforementioned technical means of this invention work together synergistically to meet the long-term use requirements of the repair adhesive in the harsh environment of salt ponds. It has good compatibility with the PVC covering film of salt ponds, and has good adhesion effect and adhesion durability to the PVC covering film. At the same time, the substrate and adhesive of the adhesive have good bonding performance, the interface bonding is not easy to fail, and the adhesive has good durability, which can maintain good bonding and repair performance for a long time in the harsh environment of salt ponds.

[0038] (2) According to the test, the tensile strength of the PVC substrate of the salt pond covering membrane special repair adhesive of the present invention is 25.0-25.2MPa, the elongation at break is 262-267%, the thermal weight loss initiation temperature is 258-261℃, and the water contact angle is 95-96°; at the same time, the peel force between the PVC substrate and the adhesive layer of the salt pond covering membrane special repair adhesive is 14.2-14.6lbf / in; after the salt pond covering membrane special repair adhesive is pasted to the PVC covering membrane, the peel force between the repair adhesive and the PVC covering membrane is 11.1-11.2lbf / in.

[0039] (3) According to the test, after boiling in boiling water for 4 hours, the peel strength retention rate between the PVC substrate and the adhesive layer of the salt pond covering membrane of the present invention can still reach 92.0%; after 12 temperature cycles from -20℃ to 70℃, the peel strength retention rate between the PVC substrate and the adhesive layer can still reach 98.1%; after 1000 hours of salt spray aging, the peel strength retention rate between the PVC substrate and the adhesive layer can still reach 85.2%.

[0040] (4) According to the test, the minimum temperature resistance of the special repair adhesive for salt pond covering membrane of the present invention after being pasted onto the PVC covering membrane is -40℃ after 24 hours; after being pasted onto the PVC covering membrane and left to stand in a constant temperature environment of 70℃ for 42 days, the peel force retention rate between the repair adhesive and the PVC covering membrane can still reach 90.3%; after being pasted onto the PVC covering membrane and soaked in brine at 25°Bé (Baumé degree) at a temperature of 60℃ for 28 days, the peel force retention rate between the repair adhesive and the PVC covering membrane can still reach 84.0%.

[0041] (5) The application method of the special repair adhesive for salt pond covering membrane of the present invention is convenient and can quickly repair the damaged parts of the salt crystallization pond covering membrane. The repair size can be flexibly cut according to the size of the crack. The repair process is simple and efficient, which is conducive to industrial-scale application. Detailed Implementation

[0042] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0043] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," etc., are used to distinguish similar objects and are not used to describe a particular order or sequence. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0044] This invention provides a special repair adhesive for salt pond cover membranes, comprising, from top to bottom, a PVC substrate, an adhesive layer, and a release film layer. The preparation method of the special repair adhesive for salt pond cover membranes includes the following steps: preparing a substrate reinforcement phase, preparing a PVC substrate, and composite molding.

[0045] The preparation of the substrate reinforcement phase includes the following steps: a primary reaction and a secondary reaction.

[0046] The method for the primary reaction is as follows: itaconic anhydride is added to a reactor containing 6.5-7.5 times its weight of N,N-dimethylformamide. The air in the reactor is completely replaced with dry nitrogen. Under a nitrogen atmosphere, the mixture is stirred and heated to 40-45°C, and stirred for 20-40 minutes to completely dissolve the itaconic anhydride. The mixture is then stirred and heated to 48-50°C, and an isophorone diamine solution is added dropwise while stirring, ensuring that the addition of the isophorone diamine solution is completed within 50-70 minutes. After the isophorone diamine solution is completely added, the mixture is stirred and stirred for 5-6 hours, and then allowed to cool naturally to room temperature to obtain the reaction solution. 1.5-2.5 times the volume of ice water is added to the reaction solution, and the mixture is allowed to stand and precipitate. The precipitate is collected by filtration, washed to remove impurities, and then dried to obtain the primary reactant, namely itaconic acid isophorone diamine diamide.

[0047] In the aforementioned reaction, the molar ratio of itaconic anhydride to isophorone diamine was 2-2.05:1.

[0048] The isophorone diamine solution is an N,N-dimethylformamide solution of isophorone diamine with a concentration of 30-32 wt%.

[0049] The secondary reaction method is as follows: the primary reactant is added to a reactor containing 6.5-7.5 times its weight of N,N-dimethylformamide, stirred and heated to 60-65℃, and stirred for 30-40 minutes. Then, the pH of the system is adjusted to 6.0±0.1 using ammonia water with a mass concentration of 5-7wt%. Under stirring conditions of 300-400 rpm, the composite metal hydroxide slurry is added and stirred for 5-6 hours. During the stirring reaction, the pH of the system is maintained in the range of 5.8-6.2 using ammonia water with a mass concentration of 5-8wt%. After the stirring reaction is completed, the mixture is naturally cooled to room temperature to obtain the reaction solution. 1.5-2.5 times its volume of ethanol solution (volume concentration 50-55%) is added to the reaction solution, and the mixture is allowed to stand to precipitate. The precipitate is collected by filtration, washed to remove impurities, and dried to obtain the substrate reinforcing phase, namely the zinc-zirconium bimetallic / itaconic isophorone diamine diamide acid complex.

[0050] In the secondary reaction, the composite metal hydroxide slurry is an N,N-dimethylformamide dispersion containing zinc hydroxide and zirconium hydroxide; the concentration of zinc hydroxide is 9-9.5 wt%, and the concentration of zirconium hydroxide is 1.9-2.3 wt%.

[0051] The weight ratio of the primary reactant to the composite metal hydroxide slurry is 1:1.7-1.9.

[0052] In this embodiment of the invention, in the first reaction, itaconic anhydride and isophorone diamine undergo a ring-opening amidation reaction to form a diamic acid product. The itaconic anhydride introduces reactive carbon-carbon double bonds, providing potential functionalization sites for subsequent PVC processing or use. The isophorone diamine introduces an alicyclic structure, improving the rigidity and hydrophobicity of the PVC substrate, thereby enhancing the adhesive's resistance to high-humidity salt spray environments and improving the adhesion durability of the adhesive to the PVC cover film. In the second reaction, the diamic acid product contacts a composite metal hydroxide slurry containing zinc and zirconium sources. Through the coordination of carboxyl groups with the metal centers, a bimetallic coordination polymer network is formed, producing a zinc-zirconium bimetallic / itaconic acid-isophorone diamine diamic acid complex (i.e., the substrate reinforcement phase), further improving the stability and antibacterial properties of the PVC substrate.

[0053] The method for preparing the PVC substrate is as follows: Polyvinyl chloride resin (PVC), substrate reinforcing phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide are added to a high-speed mixer and mixed evenly to obtain a mixture; the mixture is then transferred to an internal mixer, and the mixing temperature is controlled at 130-100°C. The mixture is held at 35℃ for 5-8 minutes to obtain a granulated material. The granulated material is then fed into a four-roll calender for calendering and film formation. During the calendering process, the temperatures of the four-roll calender rolls are controlled at 160-165℃, roll 2 at 165-170℃, roll 3 at 170-175℃, and roll 4 at 165-170℃. The film thickness is controlled to be 0.1-0.3mm by adjusting the roll gap to obtain a PVC substrate.

[0054] In the preparation of the PVC substrate, the weight ratio of polyvinyl chloride resin (PVC), substrate reinforcing phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide is 100-105:4.5-5.5:28-32:5-6:0.3-0.4:0.3-0.4:0.8-0.9:0.4-0.5:0.8-1:11-13:4-5.

[0055] In this embodiment of the invention, polyvinyl chloride resin (PVC), a substrate reinforcement phase, and additives are mixed and calendered into a film to form a PVC substrate. The substrate reinforcement phase effectively reinforces the PVC substrate in several ways: it not only disperses in the PVC substrate as a rigid substrate reinforcement phase, but also improves the tensile strength, elongation at break, thermal stability, and hydrophobicity of the PVC substrate through the interaction between the substrate reinforcement phase and the PVC molecular chains, thereby improving the adhesive's resistance to high temperature and high humidity environments and thus enhancing the adhesion durability of the adhesive to the PVC cover film; and it introduces zinc and zirconium metal coordination centers on the surface of the PVC substrate through the substrate reinforcement phase as effective binding sites for subsequent bonding with the adhesive, thereby improving the bonding performance between the PVC substrate and the adhesive layer.

[0056] The composite molding method is as follows: Acrylic pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 are added to ethyl acetate and stirred at room temperature for 30-40 minutes to obtain an adhesive with a solid content of 30-35 wt%. The adhesive is then coated onto the release surface of a release film to form an adhesive layer. The film is then placed in an environment of 95-100℃ and dried until the adhesive layer thickness reaches 25-35 μm to obtain a release film layer with the adhesive layer. The release film layer with the adhesive layer is then laminated with the glossy surface of a PVC substrate and placed in an environment of 40-45℃ for 48-60 hours to obtain a special repair adhesive for salt pond covering membranes.

[0057] In the composite molding process, the weight ratio of acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 is 100-105:3-4:0.6-0.8:0.5-0.6.

[0058] The acrylic pressure-sensitive adhesive has a room temperature viscosity of 18,000-20,000 mPa·s, a hydroxyl value of 20-30 mgKOH / g, and a glass transition temperature of -45℃ to -40℃.

[0059] In this embodiment of the invention, an adhesive is formed by combining an acrylic pressure-sensitive adhesive with a curing agent and other additives. A predetermined thickness of adhesive layer is then formed on the release surface of the release film. Finally, it is laminated with the smooth surface of a PVC substrate to produce a special repair adhesive for salt lake covering film. During this process, the silane coupling agent in the adhesive bonds with the zinc and zirconium metal coordination centers exposed on the surface reinforcing phase of the PVC substrate, thereby improving the bonding performance between the PVC substrate and the adhesive layer. This further enhances the water resistance and stability of the repair adhesive in humid and hot environments, ensuring the adhesion durability of the adhesive to the PVC covering film.

[0060] In the preparation of the salt pond covering membrane repair adhesive of this invention, a zinc-zirconium bimetallic / itaconic isophorone diamine diamide complex is introduced into the PVC substrate. The introduced zinc and zirconium metal coordination centers serve as subsequent binding sites with the adhesive layer, changing the bonding mode between the PVC substrate and the adhesive layer from the original physical adsorption to chemical anchoring. This effectively improves the bonding performance between the PVC substrate and the adhesive layer, and enhances the peel strength and environmental aging resistance of the adhesive layer. At the same time, the interaction between the organic ligand portion of the reinforcing phase and the PVC molecular chain stabilizes the PVC network structure and inhibits the migration of plasticizers. Furthermore, the introduction of the substrate reinforcing phase improves the tensile strength, elongation at break, thermal stability, and hydrophobicity of the PVC substrate. Furthermore, the introduction of the substrate reinforcement phase can also avoid adverse interactions between the adhesive and the PVC substrate. Through the interaction between the zinc and zirconium metal coordination centers and their organic ligands introduced into the substrate reinforcement phase and the PVC molecular chains, the PVC molecular network is stabilized, and the migration of plasticizers is inhibited. The alicyclic structure introduced by isophorone diamine in the substrate reinforcement phase provides hydrophobicity, effectively preventing moisture penetration into the PVC substrate in high-humidity environments. In addition, the zinc and zirconium metal coordination centers introduced into the PVC substrate surface by the substrate reinforcement phase uniformly disperse the bonding stress between the PVC substrate and the adhesive, avoiding interface cracking caused by stress concentration, improving the adhesion durability and stability of the adhesive to the PVC cover film, and achieving a stable and durable interface bond with the PVC cover film.

[0061] This invention also provides the application of the aforementioned salt pond covering film repair adhesive in the repair of the covering film of a salt evaporation crystallization pond. The salt pond covering film repair adhesive is cut according to the size of the tear in the covering film. After removing the release film from the overlapping contact portion of the covering film and the salt pond covering film repair adhesive, the salt pond covering film repair adhesive is pasted to the tear in the covering film to complete the repair of the covering film of the salt evaporation crystallization pond.

[0062] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described below in conjunction with some specific embodiments.

[0063] Example 1

[0064] This embodiment provides a special repair adhesive for salt pond cover membranes, which consists of a PVC substrate, an adhesive layer, and a release film layer arranged sequentially from top to bottom. The specific steps for preparing the special repair adhesive for salt pond cover membranes are as follows:

[0065] 1. Preparation of substrate reinforcement phase

[0066] (1) Primary reaction

[0067] Itaconic anhydride was added to a reactor containing 7 times its weight of N,N-dimethylformamide. The air in the reactor was completely replaced with dry nitrogen. Under nitrogen atmosphere, the mixture was stirred and heated to 40°C, and kept at this temperature for 40 minutes to completely dissolve the itaconic anhydride. The temperature was then raised to 50°C, and isophorone diamine solution was added dropwise while maintaining the temperature. The addition of isophorone diamine solution was controlled to be completed within 50 minutes. After the isophorone diamine solution was completely added, the mixture was stirred and kept at this temperature for 5 hours. The mixture was then allowed to cool naturally to room temperature to obtain the reaction solution. Two volumes of ice water were added to the reaction solution, and the mixture was allowed to stand and precipitate. The precipitate was collected by filtration, washed to remove impurities, and then dried to obtain the primary reactant, namely itaconic acid isophorone diamine diamide.

[0068] The molar ratio of itaconic anhydride to isophorone diamine used was 2.05:1.

[0069] The isophorone diamine solution is an N,N-dimethylformamide solution of isophorone diamine with a concentration of 30 wt%.

[0070] (2) Secondary reaction

[0071] The reactants were added to a reactor containing 7 times their weight of N,N-dimethylformamide, stirred and heated to 60°C, and kept at this temperature for 40 min. The pH of the system was then adjusted to 6.0 using 5 wt% ammonia. The composite metal hydroxide slurry was added while stirring at 350 rpm, and the reaction was continued for 5 h with 5 wt% ammonia to maintain the pH of the system within the range of 5.8-6.2. After the reaction was completed, the mixture was allowed to cool naturally to room temperature to obtain the reaction solution. Two volumes of ethanol solution (50% volume concentration) were added to the reaction solution, and the mixture was allowed to settle and precipitate. The precipitate was collected by filtration, washed to remove impurities, and dried to obtain the substrate reinforcing phase, namely the zinc-zirconium bimetallic / itaconic isophorone diamine diamide complex.

[0072] The composite metal hydroxide slurry is an N,N-dimethylformamide dispersion containing zinc hydroxide and zirconium hydroxide; the zinc hydroxide concentration is 9 wt% and the zirconium hydroxide concentration is 2.3 wt%.

[0073] The weight ratio of the primary reactant to the composite metal hydroxide slurry is 1:1.7.

[0074] 2. Preparation of PVC substrate

[0075] Polyvinyl chloride resin (PVC), substrate reinforcement phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide are added to a high-speed mixer and mixed evenly to obtain a mixture. The mixture is then transferred to an internal mixer, and the mixing temperature is controlled at 130℃ for 7 minutes to obtain a kneaded material. The kneaded material is then fed into a four-roll calender for calendering to form a film. During the calendering process, the temperatures of roll 1, roll 2, roll 3, and roll 4 of the four-roll calender are controlled at 160℃, roll 2 at 165℃, roll 3 at 170℃, and roll 4 at 165℃. The film thickness is controlled to be 0.2mm by adjusting the roll gap to obtain a PVC substrate.

[0076] The weight ratio of polyvinyl chloride resin (PVC), substrate reinforcing phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide is 100:4.5:28:5:0.3:0.3:0.8:0.4:0.8:11:4.

[0077] 3. Composite molding

[0078] Acrylic pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 were added to ethyl acetate and stirred at room temperature for 30 minutes to obtain an adhesive with a solid content of 32 wt%. The adhesive was coated onto the release surface of a release film to form an adhesive layer. The film was then placed in a 95°C environment and dried until the adhesive layer thickness reached 30 μm to obtain a release film layer with an adhesive layer. The release film layer with the adhesive layer was then laminated with the glossy surface of a PVC substrate and placed in a 40°C environment for 48 hours to obtain a special repair adhesive for salt pond covering membranes.

[0079] The weight ratio of acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 is 100:3:0.6:0.5.

[0080] The acrylic pressure-sensitive adhesive used in this embodiment was purchased commercially and has a room temperature viscosity of 18000 mPa·s, a hydroxyl value of 26 mgKOH / g, and a glass transition temperature of -45℃.

[0081] This embodiment also provides the application of the aforementioned salt pond covering film repair adhesive in the repair of the covering film of the salt evaporation crystallization pond. The salt pond covering film repair adhesive is cut according to the size of the tear in the covering film. After removing the release film of the overlapping contact part between the covering film and the salt pond covering film repair adhesive, the salt pond covering film repair adhesive is pasted to the tear in the covering film to complete the repair of the covering film of the salt evaporation crystallization pond.

[0082] Example 2

[0083] This embodiment provides a special repair adhesive for salt pond cover membranes, which consists of a PVC substrate, an adhesive layer, and a release film layer arranged sequentially from top to bottom. The specific steps for preparing the special repair adhesive for salt pond cover membranes are as follows:

[0084] 1. Preparation of substrate reinforcement phase

[0085] (1) Primary reaction

[0086] Itaconic anhydride was added to a reactor containing 7 times its weight of N,N-dimethylformamide. The air in the reactor was completely replaced with dry nitrogen. Under nitrogen atmosphere, the mixture was stirred and heated to 42°C, and kept at this temperature for 30 minutes to completely dissolve the itaconic anhydride. The temperature was then increased to 50°C, and isophorone diamine solution was added dropwise while maintaining the temperature. The addition of isophorone diamine solution was controlled to be completed within 70 minutes. After the isophorone diamine solution was completely added, the mixture was stirred and kept at this temperature for 5.5 hours. The mixture was then allowed to cool naturally to room temperature to obtain the reaction solution. Two volumes of ice water were added to the reaction solution, and the mixture was allowed to stand and precipitate. The precipitate was collected by filtration, washed to remove impurities, and then dried to obtain the primary reactant, namely itaconic acid isophorone diamine diamide.

[0087] The molar ratio of itaconic anhydride to isophorone diamine used was 2.05:1.

[0088] The isophorone diamine solution is an N,N-dimethylformamide solution of isophorone diamine with a concentration of 30 wt%.

[0089] (2) Secondary reaction

[0090] The reactants were added to a reactor containing 7 times their weight of N,N-dimethylformamide, stirred and heated to 60°C, and kept at this temperature for 40 min. The pH of the system was then adjusted to 6.0 using 5 wt% ammonia. The composite metal hydroxide slurry was added while stirring at 350 rpm, and the reaction was maintained at this temperature for 5.5 h. During the reaction, the pH of the system was maintained between 5.8 and 6.2 using 5 wt% ammonia. After the reaction was completed, the mixture was allowed to cool naturally to room temperature to obtain the reaction solution. Two volumes of ethanol solution (50% volume concentration) were added to the reaction solution, and the mixture was allowed to stand and precipitate. The precipitate was collected by filtration, washed to remove impurities, and then dried to obtain the substrate reinforcing phase, namely the zinc-zirconium bimetallic / itaconic isophorone diamine diamide complex.

[0091] The composite metal hydroxide slurry is an N,N-dimethylformamide dispersion containing zinc hydroxide and zirconium hydroxide; the zinc hydroxide concentration is 9.3 wt% and the zirconium hydroxide concentration is 2.0 wt%.

[0092] The weight ratio of the primary reactant to the composite metal hydroxide slurry is 1:1.8.

[0093] 2. Preparation of PVC substrate

[0094] Polyvinyl chloride resin (PVC), substrate reinforcement phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide are added to a high-speed mixer and mixed evenly to obtain a mixture. The mixture is then transferred to an internal mixer, and the mixing temperature is controlled at 132℃ for 6 minutes to obtain a kneaded material. The kneaded material is then fed into a four-roll calender for calendering to form a film. During the calendering process, the temperatures of roll 1, roll 2, roll 3, and roll 4 of the four-roll calender are controlled at 160℃, roll 2 at 165℃, roll 3 at 170℃, and roll 4 at 165℃. The film thickness is controlled to be 0.2mm by adjusting the roll gap to obtain a PVC substrate.

[0095] The weight ratio of polyvinyl chloride resin (PVC), substrate reinforcing phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide is 102:5:30:5.7:0.35:0.35:0.86:0.44:0.9:12:4.5.

[0096] 3. Composite molding

[0097] Acrylic pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 were added to ethyl acetate and stirred at room temperature for 35 minutes to obtain an adhesive with a solid content of 32 wt%. The adhesive was coated onto the release surface of a release film to form an adhesive layer. The film was then placed in a 95°C environment and dried until the adhesive layer thickness reached 30 μm to obtain a release film layer with an adhesive layer. The release film layer with the adhesive layer was laminated to the glossy surface of a PVC substrate and then placed in a 40°C environment for 50 hours to obtain a special repair adhesive for salt pond covering membranes.

[0098] The weight ratio of acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 is 103:3.6:0.65:0.55.

[0099] The acrylic pressure-sensitive adhesive used in this embodiment was purchased commercially and has a room temperature viscosity of 18000 mPa·s, a hydroxyl value of 26 mgKOH / g, and a glass transition temperature of -45℃.

[0100] This embodiment also provides the application of the aforementioned salt pond covering film repair adhesive in the repair of the covering film of the salt evaporation crystallization pond. The salt pond covering film repair adhesive is cut according to the size of the tear in the covering film. After removing the release film of the overlapping contact part between the covering film and the salt pond covering film repair adhesive, the salt pond covering film repair adhesive is pasted to the tear in the covering film to complete the repair of the covering film of the salt evaporation crystallization pond.

[0101] Example 3

[0102] This embodiment provides a special repair adhesive for salt pond cover membranes, which consists of a PVC substrate, an adhesive layer, and a release film layer arranged sequentially from top to bottom. The specific steps for preparing the special repair adhesive for salt pond cover membranes are as follows:

[0103] 1. Preparation of substrate reinforcement phase

[0104] (1) Primary reaction

[0105] Itaconic anhydride was added to a reactor containing 7 times its weight of N,N-dimethylformamide. The air in the reactor was completely replaced with dry nitrogen. Under nitrogen atmosphere, the mixture was stirred and heated to 40°C, and kept at this temperature for 20 minutes to completely dissolve the itaconic anhydride. The temperature was then raised to 50°C, and isophorone diamine solution was added dropwise while maintaining the temperature. The addition of isophorone diamine solution was controlled to be completed within 60 minutes. After the isophorone diamine solution was completely added, the mixture was stirred and kept at this temperature for 6 hours. The mixture was then allowed to cool naturally to room temperature to obtain the reaction solution. Two volumes of ice water were added to the reaction solution, and the mixture was allowed to stand and precipitate. The precipitate was collected by filtration, washed to remove impurities, and then dried to obtain the primary reactant, namely itaconic acid isophorone diamine diamide.

[0106] The molar ratio of itaconic anhydride to isophorone diamine used was 2.05:1.

[0107] The isophorone diamine solution is an N,N-dimethylformamide solution of isophorone diamine with a concentration of 32 wt%.

[0108] (2) Secondary reaction

[0109] The reactants were added to a reactor containing 7 times their weight of N,N-dimethylformamide, stirred and heated to 65°C, and kept at this temperature for 30 min. The pH of the system was then adjusted to 6.0 ± 0.1 using 5 wt% ammonia. The composite metal hydroxide slurry was added while stirring at 400 rpm, and the reaction was continued for 6 h with stirring. During the reaction, the pH of the system was maintained within the range of 5.8-6.2 using 5 wt% ammonia. After the reaction was completed, the mixture was allowed to cool naturally to room temperature to obtain the reaction solution. Two volumes of ethanol solution (50% volume concentration) were added to the reaction solution, and the mixture was allowed to stand and precipitate. The precipitate was collected by filtration, washed to remove impurities, and then dried to obtain the substrate reinforcing phase, namely the zinc-zirconium bimetallic / itaconic isophorone diamine diamide complex.

[0110] The composite metal hydroxide slurry is an N,N-dimethylformamide dispersion containing zinc hydroxide and zirconium hydroxide; the zinc hydroxide concentration is 9.5 wt% and the zirconium hydroxide concentration is 1.9 wt%.

[0111] The weight ratio of the primary reactant to the composite metal hydroxide slurry is 1:1.9.

[0112] 2. Preparation of PVC substrate

[0113] Polyvinyl chloride resin (PVC), substrate reinforcement phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide are added to a high-speed mixer and mixed evenly to obtain a mixture. The mixture is then transferred to an internal mixer, and the mixing temperature is controlled at 135℃ for 5 minutes to obtain a kneaded material. The kneaded material is then fed into a four-roll calender for calendering to form a film. During the calendering process, the temperatures of roll 1, roll 2, roll 3, and roll 4 of the four-roll calender are controlled at 165℃, roll 2 at 170℃, roll 3 at 175℃, and roll 4 at 170℃. The film thickness is controlled to be 0.2mm by adjusting the roll gap to obtain a PVC substrate.

[0114] The weight ratio of polyvinyl chloride resin (PVC), substrate reinforcing phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide is 105:5.5:32:6:0.4:0.4:0.9:0.5:1:13:5.

[0115] 3. Composite molding

[0116] Acrylic pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 were added to ethyl acetate and stirred at room temperature for 40 minutes to obtain an adhesive with a solid content of 32 wt%. The adhesive was coated onto the release surface of a release film to form an adhesive layer. The film was then placed in an environment of 100°C and dried until the adhesive layer thickness reached 30 μm to obtain a release film layer with an adhesive layer. The release film layer with an adhesive layer was laminated with the glossy surface of a PVC substrate and placed in an environment of 45°C for 60 hours to obtain a special repair adhesive for salt pond covering membranes.

[0117] The weight ratio of acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 is 105:4:0.8:0.6.

[0118] The acrylic pressure-sensitive adhesive used in this embodiment was purchased commercially and has a room temperature viscosity of 18000 mPa·s, a hydroxyl value of 26 mgKOH / g, and a glass transition temperature of -45℃.

[0119] This embodiment also provides the application of the aforementioned salt pond covering film repair adhesive in the repair of the covering film of the salt evaporation crystallization pond. The salt pond covering film repair adhesive is cut according to the size of the tear in the covering film. After removing the release film of the overlapping contact part between the covering film and the salt pond covering film repair adhesive, the salt pond covering film repair adhesive is pasted to the tear in the covering film to complete the repair of the covering film of the salt evaporation crystallization pond.

[0120] Comparative Example 1

[0121] To avoid unnecessary details, Comparative Example 1 adopts the technical solution of Example 2, the difference being that the secondary reaction is omitted in the step of preparing the substrate reinforcement phase, and the primary reactant obtained from the primary reaction is used as the substrate reinforcement phase in the subsequent step of preparing the PVC substrate.

[0122] Comparative Example 2

[0123] To avoid unnecessary details, Comparative Example 2 adopts the technical solution of Example 2, the difference being that the step of preparing the substrate reinforcement phase is omitted, and the addition of the substrate reinforcement phase is omitted in the step of preparing the PVC substrate.

[0124] During the preparation of the salt pond covering membrane repair adhesive for Examples 1-3 and Comparative Examples 1-2, the tensile strength, elongation at break, thermogravimetric initiation temperature, and water contact angle of the prepared PVC substrate were tested. The tensile strength and elongation at break were tested according to the national standard GB / T 1040.3-2006 "Determination of Tensile Properties of Plastics", with the test speed controlled at 50 mm / min. The thermogravimetric initiation temperature was tested according to the national standard GB / T 33047.1-2016 "Thermogravimetric Analysis (TG) of Plastic Polymers". The water contact angle was measured using a static contact angle meter at room temperature. The specific results are shown in the table below:

[0125]

[0126] Furthermore, a 180° peel test was conducted on the PVC substrate and adhesive layer of the salt pond covering membrane repair adhesive patches of Examples 1-3 and Comparative Examples 1-2, respectively. Simultaneously, the salt pond covering membrane repair adhesive patches of Examples 1-3 and Comparative Examples 1-2 were respectively adhered to the PVC covering membrane, ensuring that the contact area between the repair adhesive patch and the PVC covering membrane was the same in each example and comparative example. After standing at room temperature for 24 hours, a 180° peel test was conducted on the repair adhesive patch and the PVC covering membrane. The 180° peel test method referenced standard ASTM D3330, and the peel rate was controlled at 12 in / min. Specific results are shown in the table below:

[0127]

[0128] Furthermore, the salt pond covering membrane repair adhesive patches of Examples 2 and Comparative Examples 1-2 were placed in boiling water for 4 hours and then removed and cooled to room temperature. A 180° peel test was then performed on the PVC substrate and adhesive layer of each repair adhesive patch. The peel force retention rate was calculated based on the peel force obtained from the aforementioned test. Additionally, the ambient temperature of the salt pond covering membrane repair adhesive patches of Examples 2 and Comparative Examples 1-2 was controlled to be increased to 70°C at a heating rate of 2°C / min, and then decreased to -20°C at a cooling rate of 2°C / min. This heating-cooling process was considered one temperature cycle and repeated 12 times. A 180° peel test was then performed on the PVC substrate and adhesive layer of each repair adhesive patch. The peel force retention rate was calculated based on the peel force obtained from the aforementioned test. Salt spray aging tests were conducted on the salt pond covering membrane repair adhesives of Examples 2 and Comparative Examples 1-2, respectively. The specific method followed the national standard GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". A 5wt% sodium chloride solution was used as the test solution, and continuous spraying was performed at a constant temperature of 35℃. After 1000 hours of salt spray aging, a 180° peel test was conducted on the PVC substrate and adhesive layer of each repair adhesive. The peel force retention rate was calculated based on the peel force obtained from the aforementioned test. The specific results are shown in the table below:

[0129]

[0130] Furthermore, the special repair adhesive patches for salt pond covering membranes of Examples 2 and Comparative Examples 1-2 were respectively adhered to PVC covering membranes, ensuring that the contact area between the repair adhesive patches and the PVC covering membranes was the same in each example and comparative example. After standing at room temperature for 24 hours, each repair adhesive patch and PVC covering membrane was placed in a low-temperature environment and left to stand for 24 hours. The presence of cracks in the repair adhesive patches was then observed. If no cracks appeared, the temperature was further reduced by 5°C and the mixture was left to stand for another 24 hours until cracks appeared. The ambient temperature at which cracks appeared was recorded. The specific results are shown in the table below:

[0131]

[0132] Furthermore, the special repair adhesive patches for salt pond covering membranes of Examples 2 and Comparative Examples 1-2 were respectively adhered to PVC covering membranes, and the contact area between the repair adhesive patches and the PVC covering membranes in each example and comparative example was controlled to be the same. After standing at room temperature for 24 hours, each repair adhesive patch and PVC covering membrane was placed in a constant temperature environment of 70°C and left to stand for 42 days. After a 180° peel test was performed on the repair adhesive patches and PVC covering membranes, the peel force retention rate was calculated based on the peel force between the PVC substrate and the adhesive layer obtained in the aforementioned test. The specific results are shown in the table below:

[0133]

[0134] Furthermore, the special repair adhesive patches for salt pond covering membranes of Examples 2 and Comparative Examples 1-2 were respectively adhered to PVC covering membranes, and the contact area between the repair adhesive patches and the PVC covering membranes in each example and comparative example was controlled to be the same. After standing at room temperature for 24 hours, each repair adhesive patch and PVC covering membrane was placed in brine at 60°C and 25°Bé (Baumé degree) for 28 days. After soaking, a 180° peel test was performed on the repair adhesive patches and PVC covering membranes. The peel force retention rate was calculated based on the peel force between the PVC substrate and the adhesive layer obtained in the aforementioned test. The specific results are shown in the table below:

[0135]

[0136] As can be seen, the preparation method of the salt pond covering membrane special repair adhesive of the present invention introduces a zinc-zirconium bimetallic / itaconic isophorone diamine diamide acid complex into the PVC substrate. The introduced zinc and zirconium metal coordination centers serve as subsequent binding sites with the adhesive layer, changing the bonding mode between the PVC substrate and the adhesive layer from the original physical adsorption to chemical anchoring. This effectively improves the bonding performance between the PVC substrate and the adhesive layer, and enhances the peel strength and environmental aging resistance of the adhesive layer. At the same time, the interaction between the organic ligand portion of the reinforcing phase and the PVC molecular chain stabilizes the PVC network structure and inhibits the migration of plasticizers. Furthermore, the introduction of the substrate reinforcing phase improves the tensile strength, elongation at break, thermal stability, and hydrophobicity of the PVC substrate.

[0137] Furthermore, the introduction of the substrate reinforcement phase can also avoid adverse interactions between the adhesive and the PVC substrate. Through the interaction between the zinc and zirconium metal coordination centers and their organic ligands introduced into the substrate reinforcement phase and the PVC molecular chains, the PVC molecular network is stabilized, improving the durability of the adhesive. The alicyclic structure introduced by isophorone diamine in the substrate reinforcement phase provides hydrophobicity, effectively isolating moisture from penetrating the PVC substrate in high-humidity environments, thus improving the adhesive's water resistance and resistance to high-humidity environments. Additionally, the zinc and zirconium metal coordination centers introduced into the PVC substrate surface by the substrate reinforcement phase uniformly disperse the bonding stress between the PVC substrate and the adhesive, preventing interface cracking caused by stress concentration, improving the adhesion durability and stability of the adhesive to the PVC cover film, and achieving a stable and durable interfacial bond with the PVC cover film.

[0138] The aforementioned technical methods work together synergistically to meet the long-term use requirements of repair adhesive in the harsh environment of salt ponds. They have good compatibility with the PVC covering film of salt ponds, and have good adhesion effect and adhesion durability to the PVC covering film. At the same time, the substrate and adhesive of the adhesive have good bonding performance, the interface bonding is not easy to fail, and the adhesive has good durability, which can maintain good bonding and repair performance for a long time in the harsh environment of salt ponds.

[0139] As can be seen from Comparative Example 1, after omitting the secondary reaction in the preparation of the substrate reinforcement phase, the substrate reinforcement phase lacks zinc-zirconium bimetallic coordination centers that can bond with the adhesive layer. The bonding between the PVC substrate and the adhesive layer is mainly based on physical adsorption, resulting in reduced interfacial bonding performance between the PVC substrate and the adhesive layer. Furthermore, the lack of the improving effect of zinc-zirconium metal on the PVC substrate reduces its heat resistance and water resistance. Specifically, the peel force between the PVC substrate and the adhesive layer of the repair adhesive is reduced, and the peel force retention rate after boiling water, temperature cycling, and salt spray aging is significantly reduced.

[0140] As can be seen from Comparative Example 2, omitting the preparation and addition of the substrate reinforcement phase further diminishes the improvement on the rigidity and hydrophobicity of the PVC substrate compared to Comparative Example 1, resulting in a significant decrease in its tensile strength, elongation at break, thermal stability, and water resistance. At the same time, the interfacial bonding performance between the PVC substrate and the adhesive layer, the adhesion effect of the repair adhesive to the PVC cover film, and the adhesion durability are all further reduced.

[0141] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0142] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a special repair adhesive for salt pond covering membranes, characterized in that, The process includes the following steps: preparing the substrate reinforcement phase, preparing the PVC substrate, and composite molding; The preparation of the substrate reinforcement phase includes the following steps: a primary reaction and a secondary reaction; The method for the primary reaction is as follows: under inert gas protection and in a solvent environment, at a temperature of 48-50°C, isophorone diamine solution is added dropwise to N,N-dimethylformamide solution containing itaconic anhydride, and the reaction is maintained at this temperature to obtain a reaction solution; after cooling and precipitation, the precipitate is collected; the precipitate is washed and dried to obtain the primary reactant. The secondary reaction method is as follows: the primary reactant is added to a solvent, heated to 60-65℃, kept at the temperature and dispersed evenly, the pH is adjusted to 6.0±0.1, and then the composite metal hydroxide slurry is added and kept at the temperature to obtain a reaction solution; the reaction solution is precipitated with ethanol solution and the precipitate is collected; the precipitate is washed and dried to obtain the substrate reinforcement phase; The composite metal hydroxide slurry contains zinc hydroxide and zirconium hydroxide; The method for preparing the PVC substrate is as follows: after mixing polyvinyl chloride resin, substrate reinforcing phase and additives, the mixture is kneaded and calendered into a film to obtain a PVC substrate with a thickness of 0.1-0.3 mm. The composite molding method involves coating an acrylic adhesive onto the release surface of a release film to obtain a release film layer with an adhesive layer; and then laminating the release film layer with the adhesive layer to the smooth surface of a PVC substrate to obtain a special repair adhesive for salt pond covering film. The acrylate adhesive is obtained by adding acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 to ethyl acetate, adjusting the solid content to 30-35 wt%, and mixing evenly.

2. The preparation method of the special repair adhesive for salt pond covering membrane according to claim 1, characterized in that, In the aforementioned reaction, the dropping time of the isophorone diamine solution is controlled to be 50-70 min; The heat preservation reaction time is 5-6 hours.

3. The preparation method of the special repair adhesive for salt pond covering membrane according to claim 1, characterized in that, In the aforementioned reaction, the molar ratio of itaconic anhydride to isophorone diamine was 2-2.05:

1. The isophorone diamine solution is an N,N-dimethylformamide solution of isophorone diamine with a concentration of 30-32 wt%.

4. The preparation method of the special repair adhesive for salt pond covering membrane according to claim 1, characterized in that, In the secondary reaction, the heat preservation reaction time after adding the composite metal hydroxide slurry is 5-6 hours; During the heat preservation reaction, the pH of the material is controlled within the range of 5.8-6.

2.

5. The method for preparing the special repair adhesive for salt pond covering membranes according to claim 1, characterized in that, In the secondary reaction, the composite metal hydroxide slurry is an N,N-dimethylformamide dispersion containing zinc hydroxide and zirconium hydroxide, with a zinc hydroxide concentration of 9-9.5 wt% and a zirconium hydroxide concentration of 1.9-2.3 wt%. The weight ratio of the primary reactant to the composite metal hydroxide slurry is 1:1.7-1.

9.

6. The method for preparing the special repair adhesive for salt pond covering membranes according to claim 1, characterized in that, In the preparation of the PVC substrate, the additives include: plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide. The weight ratio of polyvinyl chloride resin, matrix reinforcement phase, plasticizer DOP, chlorinated paraffin CP-52, antioxidant 1010, light stabilizer 944, ultraviolet absorber UV-531, stearic acid, silane coupling agent KH-550, light calcium carbonate, and rutile titanium dioxide is 100-105:4.5-5.5:28-32:5-6:0.3-0.4:0.3-0.4:0.8-0.9:0.4-0.5:0.8-1:11-13:4-5.

7. The method for preparing the special repair adhesive for salt pond covering membranes according to claim 1, characterized in that, In the composite molding process, after the acrylic adhesive is applied to the release surface of the release film, the adhesive layer thickness is adjusted to 25-35 μm after drying to obtain a release film layer with an adhesive layer.

8. The method for preparing the special repair adhesive for salt pond covering membranes according to claim 1, characterized in that, In the acrylate adhesive, the weight ratio of acrylate pressure-sensitive adhesive, isocyanate curing agent, silane coupling agent KH-550, and leveling agent BYK-354 is 100-105:3-4:0.6-0.8:0.5-0.

6. The room temperature viscosity of acrylic pressure-sensitive adhesive is 18000-20000 mPa·s, and the hydroxyl value is 20-30 mgKOH / g.

9. A special repair adhesive for salt pond covering membranes prepared by the preparation method according to any one of claims 1-8.

10. The application of the special repair adhesive for salt pond covering membranes as described in claim 9 in the repair of damaged covering membranes in salt production evaporation and crystallization ponds.

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