Supermolecular coated greenhouse film antifogging coating solution, preparation method and application thereof

Abstract

The present application relates to the technical field of high molecular antifogging coating, and particularly relates to a supermolecular coated shed film antifogging coating solution, a preparation method and application thereof, wherein acrylic acid, acrylamidoalkyl sulfonic acid, hydroxyalkyl acrylate and double-ene crosslinking monomer are used for tetra-copolymerization to construct a supermolecular matrix with carboxyl, sulfonic acid group, hydroxyl side group and crosslinking network, and a spandex antifogging agent is introduced in situ in the matrix, hydrogen bond and hydrophobic association synergistic effect between the side group functional groups and the spandex molecules are used to realize supermolecular coating, and then pH adjustment and functional additive compounding are performed to obtain the coating solution. The present application solves the problems of easy migration and precipitation of the traditional antifogging agent, coating brittleness, short effective period, and the obtained coating has comprehensive performances of long-acting antifogging, high light transmission, strong adhesion, flexible and bending-resistant, water-resistant and aging-resistant, and room temperature rapid curing, and is suitable for antifogging treatment of various agricultural shed films and greenhouse transparent materials.

Description

Technical Field

[0001] This invention relates to the field of polymeric anti-fog coating technology, specifically to a supramolecular coated anti-fog coating liquid for greenhouse films, its preparation method, and its application. Background Technology

[0002] Agricultural plastic greenhouse film is a core covering material for facility agriculture production. Its internal environment remains consistently high in humidity due to crop transpiration and soil moisture evaporation. Under these conditions, the inner surface of the film is highly susceptible to condensation of numerous tiny droplets due to temperature differences. The presence of these droplets significantly scatters and reflects incident light, drastically reducing the film's effective light transmittance. This directly impacts crop photosynthetic efficiency, leading to a chain reaction of problems such as slowed growth, delayed maturity, and reduced yield and quality. Furthermore, as droplets accumulate and grow, they fall onto crop leaves or stems, providing favorable conditions for the growth and reproduction of pathogenic microorganisms. This significantly increases the frequency of foliar diseases, forcing agricultural producers to increase the frequency and amount of pesticide application, further raising production costs and posing risks to agricultural product quality and safety. Therefore, providing the greenhouse film surface with a durable and stable anti-fog function is of significant practical importance for ensuring efficient production in facility agriculture.

[0003] Currently, the widely used anti-fogging treatment methods for greenhouse films are mainly divided into two categories: internal addition and external coating. Both rely on the migration and accumulation of small-molecule surfactants for their core function. Internal addition involves mixing the anti-fogging agent into the resin matrix, relying on its gradual migration to the film surface to exert a hydrophilic spreading effect. External coating involves directly applying the anti-fogging agent solution to the film surface. However, these small-molecule anti-fogging agents generally suffer from inherent defects such as low molecular weight, limited compatibility with the substrate, and a lack of effective anchoring mechanisms. In the high-temperature and high-humidity greenhouse environment, anti-fogging components are prone to accelerated migration, surface precipitation, or even being washed away by condensation, leading to a rapid decline in anti-fogging effect and an effective duration that cannot meet the needs of the entire crop growing season. Simultaneously, repeated migration and precipitation of the anti-fogging agent can cause secondary problems such as film whitening, decreased transparency, and deterioration of the film's mechanical properties, severely restricting the economic benefits and sustainable operation of facility agriculture.

[0004] To overcome the technical limitations of small-molecule anti-fogging agents, polymeric anti-fogging coating technology has gradually become a research hotspot in recent years. The basic idea is to utilize the hydrophilicity of the polymer chain segments themselves or to construct a coating network with anti-fogging function by introducing polymerizable hydrophilic monomers. However, existing polymeric anti-fogging coating technologies still face many technical bottlenecks that urgently need to be overcome. On the one hand, most research focuses on the simple copolymerization of single or binary hydrophilic monomers. The distribution of hydrophilic groups within the molecular chain and on the coating surface is difficult to achieve uniform and controllable distribution, leading to swelling, softening, or even peeling of the coating under high humidity conditions due to excessive water absorption, resulting in unsatisfactory water resistance and weather resistance. On the other hand, the crosslinking structure design of traditional polymeric coatings lacks systematic control methods. Excessive crosslinking increases the coating's brittleness, reduces flexibility and adhesion, and easily causes micro-cracks or even large-area cracking and peeling during film tensioning or bending. Insufficient crosslinking results in a loose network structure with weak binding capacity for anti-fogging functional components, leading to disordered migration or loss of functional components to the surface during long-term use, making it difficult to achieve long-term stable anti-fogging performance. More importantly, existing technologies generally fail to solve the compatibility and stabilization problems between anti-fog functional components and polymer matrices. The functional components are mostly in a free or weakly adsorbed state, lacking an effective molecular-scale binding mechanism.

[0005] To address existing problems, this invention proposes a novel technical approach for in-situ supramolecular encapsulation of Span-based bio-based multi-hydroxyl antifogging functional components. This approach involves constructing a regulated cross-linked supramolecular matrix through quaternary copolymerization of carboxyl monomers, sulfonic acid monomers, hydroxyl monomers, and diene monomers. The matrix's side chains, rich in functional groups, form hydrogen bonds that synergistically interact with hydrophobic interactions, enabling the encapsulation of these components in situ. This approach is expected to fundamentally overcome the technical bottlenecks of traditional antifogging coatings, such as rapid migration, poor adhesion, insufficient flexibility, and short effective period. Summary of the Invention

[0006] The purpose of this invention is to provide a supramolecular coated antifog coating liquid for greenhouse films, its preparation method and application. A carboxyl-sulfonic acid-hydroxy-diene supramolecular network is constructed by quaternary copolymerization to in-situ coat Span-type antifog agents. The resulting coating has durable antifog properties, strong adhesion, water and weather resistance and can be cured at room temperature.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A method for preparing a supramolecular coated anti-fogging coating liquid for greenhouse films includes: A mixed monomer system containing acrylic acid, acrylamide alkyl sulfonic acid, hydroxyalkyl acrylate and diene crosslinking monomer is emulsified in an aqueous medium to obtain a pre-emulsion. In the presence of a free radical initiator, the pre-emulsion is subjected to a copolymerization reaction to obtain a quaternary copolymer supramolecular matrix, wherein the quaternary copolymer has carboxyl groups, sulfonic acid groups, hydroxyl side groups and crosslinked network structure derived from the monomer; At 40~60℃, a Span-type antifogging agent is added to the quaternary copolymer supramolecular matrix and mixed. The Span-type antifogging agent is in situ supramolecularly coated by the hydrogen bonding and hydrophobic association between the carboxyl group, sulfonic acid group, hydroxyl side group and Span molecule. The pH of the obtained system was adjusted to 5-8, and functional additives were added to obtain the supramolecular coated greenhouse film anti-fog coating liquid.

[0008] Furthermore, the acrylamidoalkyl sulfonic acid is 2-acrylamido-2-methylpropanesulfonic acid; and the hydroxyalkyl acrylate is hydroxyethyl acrylate or hydroxypropyl acrylate.

[0009] Furthermore, based on a total mass of 100 parts of the mixed monomer system, the amounts of each component are as follows: 10-40 parts by mass of acrylic acid, 10-35 parts by mass of acrylamide alkyl sulfonic acid, 10-30 parts by mass of hydroxyalkyl acrylate, and 1-10 parts by mass of diene crosslinking monomer.

[0010] Furthermore, the diene crosslinking monomer is ethylene glycol diacrylate, divinylbenzene, or a mixture thereof; and / or The mass ratio of the two components in the compound is 1:(0.5~2).

[0011] Furthermore, based on a total mass of 100 parts of the mixed monomer system, the amount of the Span-type antifogging agent is 5 to 25 parts by mass; the Span-type antifogging agent is at least one of sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monooleate. The Span-type antifogging agent comprises a combination of two Span-type compounds with different hydrophilic-lipophilic balance values.

[0012] Furthermore, the emulsification is carried out at a temperature of 40~60°C, the copolymerization reaction is carried out at 70~90°C for 3~6 hours, and after the copolymerization reaction is completed, a step of heat preservation and maturation at 70~90°C for 1~2 hours is also included.

[0013] Furthermore, the Span-type antifogging agent is added to the quaternary copolymer supramolecular matrix by slow dripping over a period of 30-60 minutes, followed by continued heating and stirring for 1-3 hours after the addition is complete.

[0014] Furthermore, the functional additives include leveling agents, substrate wetting agents, and adhesion promoters.

[0015] On the other hand, the present invention proposes an anti-fog coating liquid for greenhouse films, which is prepared by the above method.

[0016] On the other hand, the present invention proposes the application of the above-mentioned anti-fog coating liquid to form an anti-fog coating on the surface of polyethylene greenhouse film, ethylene-vinyl acetate copolymer greenhouse film or polyolefin greenhouse film.

[0017] The beneficial effects of this invention are: This invention solves the problems of easy migration and precipitation of functional components, difficulty in achieving both adhesion and flexibility, and insufficient duration of effect in traditional antifog coatings by constructing a quaternary copolymer supramolecular network of acrylic acid, acrylamide alkyl sulfonic acid, hydroxyalkyl acrylate and diene crosslinking monomer, and by introducing Span-type antifogging agents in situ into the network to achieve supramolecular encapsulation.

[0018] The carboxyl, sulfonic acid, and hydroxyl groups on the side chains of the quaternary copolymer form hydrogen bonds and hydrophobic associations with the Span molecules, achieving stable supramolecular encapsulation of Span-based antifogging agents at the molecular scale. The carboxyl groups form hydrogen bonds with the hydroxyl and ether oxygen atoms in the Span molecule; the sulfonic acid groups enhance the hydrogen bond network density and the stability of polar microdomains; and the hydroxyl groups increase the number of interaction sites and regulate chain segment flexibility to promote steric adaptation. The hydrophobic alkyl tails of the Span molecule form hydrophobic associations with the hydrophobic microdomains of the copolymer network. The synergistic effect of hydrogen bonds and hydrophobic interactions binds the Span molecules within the three-dimensional network framework of the copolymer, inhibiting their free migration and surface precipitation loss in high-humidity environments, ensuring long-term stability of the coating surface's hydrophilicity, thus achieving long-lasting antifogging performance.

[0019] The components of the quaternary copolymer monomers work synergistically with the diene crosslinking system to simultaneously optimize the coating's adhesion, flexibility, water resistance, and hydrophilic anti-fogging properties. The carboxyl groups provided by the acrylic unit form an interfacial anchor with the substrate surface, enhancing adhesion, and the dynamic hydrogen bonds between the carboxyl groups help dissipate internal stress. The sulfonic acid groups introduced by the acrylamide-alkyl sulfonic acid unit are highly hydrophilic and have strong dissociation properties, spreading a condensate film on the coating surface to eliminate fog droplet scattering centers and providing resistance to salt ions in the condensate. The flexible side chains of the hydroxyalkyl acrylate unit lower the rotation barrier of the copolymer backbone, endowing the coating with flexibility and resistance to bending cracking; the terminal hydroxyl groups participate in supramolecular encapsulation and enhance cohesive strength. The diene crosslinking monomer transforms the linear chain into a three-dimensional network, inhibiting water absorption and swelling under high humidity conditions and ensuring dimensional stability. Ethylene glycol diacrylate is used in combination with divinylbenzene. The former provides flexible segments that enable the network to deform, while the latter enhances the thermodynamic stability of the crosslinking points and the resistance to environmental stress cracking with a rigid benzene ring structure, making the coating adaptable to greenhouse film substrates with different moduli and surface properties.

[0020] The quaternary copolymer supramolecular matrix completes polymerization and crosslinking during the synthesis stage. After coating, it only requires solvent evaporation to cure into a film at room temperature, eliminating the need for high-temperature baking or radiation crosslinking post-treatment. This reduces construction energy consumption and equipment investment, making it suitable for online coating of greenhouse films and on-site renovation of existing greenhouse films. The preparation process uses water as the main dispersion medium, and the Span-type antifogging agent is derived from bio-based renewable raw materials. The supramolecular coating relies on non-covalent bond interactions without additional chemical modification, making the process simple and environmentally friendly.

[0021] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the preparation process of the supramolecular coating solution of the present invention; Figure 2 This is a TEM schematic diagram of the quaternary copolymer supramolecular coating solution of the present invention; Figure 3 A schematic diagram showing the light transmittance and haze test results of the membrane coated with the supramolecular coating liquid described in the embodiments of the present invention; Figure 4 This is a schematic diagram showing the contact angle test results of the anti-fog coating liquid after it forms a film on the surface of the greenhouse film according to an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In this application, the term "acrylamidoalkylsulfonic acid" refers to a monomer having an olefinic unsaturated bond and a sulfonic acid group, a typical example being 2-acrylamido-2-methylpropanesulfonic acid (AMPS). AMPS will be used as an example in the following description, but those skilled in the art will understand that other acrylamidoalkylsulfonic acid monomers with similar structures can also achieve the objectives of this invention. Example 1

[0026] The preparation method of the supramolecular coated anti-fog coating liquid for greenhouse film described in this embodiment is as follows: Add 150 parts by mass of deionized water and 2 parts by mass of sodium dodecyl sulfate to a reactor equipped with a stirrer, thermometer, and reflux condenser. Start stirring and heat to 50°C. Under stirring conditions, add 25 parts by mass of acrylic acid, 20 parts by mass of 2-acrylamido-2-methylpropanesulfonic acid, 15 parts by mass of hydroxyethyl acrylate, and 3 parts by mass of ethylene glycol diacrylate in sequence. Emulsify under stirring for 40 minutes until the system presents a uniform blue semi-transparent emulsion, thus obtaining a pre-emulsion.

[0027] Ammonium persulfate (0.6 parts by mass) was pre-prepared into a 10% aqueous solution and slowly added dropwise to the pre-emulsion under continuous stirring, with the addition process completed within 30 minutes. After the addition was complete, the system was heated to 80°C and reacted at this temperature for 4 hours, followed by aging at the same temperature for 1 hour, and then cooled to room temperature to obtain the acrylic acid-acrylamidoalkylsulfonic acid-hydroxyalkyl acrylate-diene tetromer supramolecular matrix.

[0028] The aforementioned quaternary copolymer supramolecular matrix was heated to 50°C, and under stirring conditions, 12 parts by mass of Span-60 were slowly added dropwise over a period of 60 minutes. After the addition was complete, the mixture was kept at 50°C and stirred for another 2 hours. This process utilized the hydrogen bonding and hydrophobic association between the carboxyl, sulfonic acid, and hydroxyl groups on the copolymer side chains and the Span molecules to achieve in-situ supramolecular encapsulation of the Span-based antifogging agent.

[0029] The coated system was cooled to room temperature, and its pH was adjusted to 6.5 with ammonia. Then, 0.8 parts by weight of a polyether-based leveling agent, 1.2 parts by weight of an organosilicon adhesion promoter, and 0.5 parts by weight of an antifoaming agent were added to the system, and the mixture was stirred at low speed for 40 minutes. Finally, the resulting mixture was filtered through a 100-mesh filter to obtain the supramolecular coated antifog coating liquid, designated as T-37. Example 2

[0030] The preparation method of the supramolecular coated anti-fog coating liquid for greenhouse film described in this embodiment is as follows: Add 200 parts by mass of deionized water and 2.5 parts by mass of sodium dodecylbenzenesulfonate to the reactor, heat to 45°C and stir. Then add 30 parts by mass of acrylic acid, 18 parts by mass of 2-acrylamido-2-methylpropanesulfonic acid, 12 parts by mass of hydroxyethyl acrylate and 4 parts by mass of divinylbenzene in sequence, and emulsify for 45 minutes to obtain a pre-emulsion.

[0031] Potassium persulfate was prepared into an aqueous solution at 0.7 parts by mass and slowly added dropwise to the pre-emulsion. The system was then heated to 85°C for copolymerization reaction for 3.5 hours. After the reaction was completed, the mixture was kept at the temperature for 1 hour to mature. After cooling, the quaternary copolymer supramolecular matrix was obtained.

[0032] Adjust the substrate temperature to 55℃, and slowly add 15 parts by weight of Span-80 over a period of 30 to 60 minutes. After the addition is complete, continue to keep the substrate warm for 1.5 hours.

[0033] After the system cooled, the pH was adjusted to 7.0 with triethanolamine, and 4 parts by weight of functional additives including leveling agents and wetting agents were added. After thorough stirring and filtration, a supramolecular coated film anti-fog coating liquid was obtained, which was numbered T-46. Example 3

[0034] As described in this embodiment, the diene crosslinking monomer in the supramolecular coated antifog coating liquid is a combination of ethylene glycol diacrylate and divinylbenzene, and the preparation method is as follows: Add 180 parts by weight of deionized water and 3 parts by weight of a composite emulsifier composed of sodium dodecyl sulfate and fatty alcohol polyoxyethylene ether to a reaction vessel, and heat to 55°C. While stirring, add 20 parts by weight of acrylic acid, 25 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, 18 parts by weight of hydroxyethyl acrylate, and a diene crosslinking monomer complex composed of 2 parts by weight of ethylene glycol diacrylate and 2 parts by weight of divinylbenzene. Emulsify for 50 minutes to obtain a pre-emulsion.

[0035] 0.5 parts by mass of azobisisobutyramidine hydrochloride was added to the pre-emulsion as an initiator, and the temperature was raised to 78°C for copolymerization reaction for 4.5 hours. Then, the mixture was kept at the temperature for 1.5 hours to obtain a quaternary copolymer supramolecular matrix with a rigid-flexible crosslinked structure.

[0036] At 50°C, 10 parts by weight of a compound antifogging agent consisting of Span-40 and Span-60 were added to the matrix over a period of 30 to 60 minutes. After the addition was completed, the matrix was kept warm and covered for 2 hours.

[0037] After cooling, the pH value was adjusted to 6.8, and 3.5 parts by weight of film-forming aid and leveling agent were added. The mixture was mixed evenly and filtered to obtain a supramolecular coated greenhouse film anti-fog coating liquid, which was numbered T-55. Example 4

[0038] The supramolecular coated antifog coating liquid for greenhouse films described in this embodiment uses a low amount of diene crosslinking monomer, resulting in a coating with high flexibility. The preparation method is as follows: Add 120 parts by weight of deionized water and 1.5 parts by weight of emulsifier to the reaction vessel and stir to mix at 40°C. Add 15 parts by weight of acrylic acid, 25 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, 25 parts by weight of hydroxyethyl acrylate, and 1.5 parts by weight of ethylene glycol diacrylate, and emulsify to obtain a pre-emulsion.

[0039] Add 0.3 parts by mass of initiator, heat the system to 75°C and copolymerize for 5 hours to obtain a soft quaternary copolymer supramolecular matrix with low crosslinking density.

[0040] At 45°C, a total of 8 parts by mass of Span-20 were added dropwise to the above matrix over a period of 30 to 60 minutes, followed by heat preservation and coating for 2.5 hours.

[0041] After cooling, the pH value was adjusted to 6.0, 2 parts by mass of functional additives were added, and the mixture was discharged after filtration to obtain a supramolecular coated greenhouse film anti-fog coating liquid, which was numbered T-64. Example 5

[0042] The supramolecular-coated anti-fog coating liquid for greenhouse films described in this embodiment contains a high amount of diene crosslinking monomers, resulting in a coating with excellent aging resistance. The preparation method is as follows: Add 250 parts by mass of deionized water and 4 parts by mass of emulsifier to the reactor, and heat to 60°C. Under stirring, add 35 parts by mass of acrylic acid, 15 parts by mass of 2-acrylamido-2-methylpropanesulfonic acid, 10 parts by mass of hydroxyethyl acrylate, and 6 parts by mass of divinylbenzene, and emulsify to obtain a pre-emulsion.

[0043] Add 1.2 parts by weight of initiator to it, heat to 90°C and carry out copolymerization reaction for 3 hours to obtain a quaternary copolymer supramolecular matrix with high crosslinking density.

[0044] At 60°C, 20 parts by weight of Span-80 were added dropwise to the matrix over a period of 30 to 60 minutes. After the addition was complete, the matrix was kept warm and covered for 3 hours.

[0045] After cooling, the pH value was adjusted to 7.5 with alkaline solution, and a total of 6 parts by weight of functional additives, including weather-resistant additives, were added. The mixture was stirred and filtered to obtain a supramolecular coated greenhouse film anti-fog coating liquid with excellent aging resistance, which was numbered Anti-T-73. Example 6

[0046] The coating liquid T-37 prepared in Example 1 was applied to the surface of polyethylene greenhouse film by scraping. After curing at room temperature for 30 minutes, performance tests were conducted.

[0047] Figure 2 This is a TEM image of the quaternary copolymer supramolecular coating liquid of the present invention. The image clearly shows that the Span-type antifogging agent, as indicated by the dark areas, is uniformly dispersed at the nanoscale and coated within the quaternary copolymer matrix, as indicated by the bright areas, forming a stable supramolecular composite structure. This verifies the in-situ supramolecular coating effect described in this invention.

[0048] Anti-fogging durability test: The coated greenhouse film was placed in a high-humidity environment at room temperature, and the fogging situation on the inner surface was continuously observed. The result showed that the fog-free period exceeded 1200 hours. It should be noted that this duration significantly exceeds the reported levels of traditional small-molecule anti-fogging agent coatings and conventional hydrophilic polymer coatings, fully demonstrating the stabilization effect achieved by the present invention through supramolecular encapsulation.

[0049] Transmittance test: The test shall be conducted in accordance with GB / T 2410-2008 "Determination of transmittance and haze of transparent plastics", and the visible light transmittance shall not be less than 92%.

[0050] Adhesion test: The cross-cut test was conducted according to GB / T 9286-2021 "Paints and Varnishes Cross-cut Test", and the adhesion reached level 0.

[0051] Water resistance test: The coated greenhouse film was immersed in deionized water for 72 hours. After removal, it was observed that the coating did not peel off or turn white, and the anti-fog function did not decrease.

[0052] Flexibility test: The coated greenhouse film was subjected to a 180° bending test on a shaft with a diameter of 2 mm. No cracks were generated on the coating surface.

[0053] Aging resistance test: The coated greenhouse film is placed in a UV aging test chamber for accelerated aging for 500 hours to test the anti-fogging performance after aging. The anti-fogging performance retention rate is not less than 90% compared with that before aging.

[0054] Test results show that the supramolecular coated greenhouse film anti-fog coating liquid provided by the present invention exhibits significant comprehensive advantages in terms of anti-fog durability, light transmittance, adhesion, water resistance, flexibility and weather resistance.

[0055] In summary, this invention proposes a supramolecular anti-fogging coating liquid for greenhouse films, its preparation method, and its application. A supramolecular matrix with carboxyl groups, sulfonic acid groups, hydroxyalkyl acrylate, and diene crosslinking monomers is constructed through quaternary copolymerization. Span-type anti-fogging agents are then introduced in situ into this matrix. The supramolecular coating is achieved through the synergistic effect of hydrogen bonding and hydrophobic association between the side group functional groups and Span molecules. The coating liquid is then obtained after pH adjustment and compounding with functional additives. This invention solves the problems of easy migration and precipitation, coating brittleness, and short effective period of traditional anti-fogging agents. The resulting coating possesses comprehensive properties such as long-lasting anti-fogging, high light transmittance, strong adhesion, flexibility and bend resistance, water and aging resistance, and rapid curing at room temperature. It is suitable for anti-fogging treatment of various agricultural greenhouse films and transparent greenhouse materials.

[0056] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a supramolecularly coated anti-fog coating liquid for greenhouse films, characterized in that, include: A mixed monomer system containing acrylic acid, acrylamide alkyl sulfonic acid, hydroxyalkyl acrylate and diene crosslinking monomer is emulsified in an aqueous medium to obtain a pre-emulsion. In the presence of a free radical initiator, the pre-emulsion is subjected to a copolymerization reaction to obtain a quaternary copolymer supramolecular matrix, wherein the quaternary copolymer has carboxyl groups, sulfonic acid groups, hydroxyl side groups and crosslinked network structure derived from the monomer; At 40~60℃, a Span-type antifogging agent is added to the quaternary copolymer supramolecular matrix and mixed. The Span-type antifogging agent is in situ supramolecularly coated by the hydrogen bonding and hydrophobic association between the carboxyl group, sulfonic acid group, hydroxyl side group and Span molecule. The pH of the obtained system was adjusted to 5-8, and functional additives were added to obtain the supramolecular coated greenhouse film anti-fog coating liquid.

2. The method as described in claim 1, characterized in that, The acrylamide alkyl sulfonic acid is 2-acrylamido-2-methylpropanesulfonic acid; the hydroxyalkyl acrylate is hydroxyethyl acrylate or hydroxypropyl acrylate.

3. The method as described in claim 1, characterized in that, Based on a total mass of 100 parts of the mixed monomer system, the amounts of each component are as follows: 10-40 parts by mass of acrylic acid, 10-35 parts by mass of acrylamide alkyl sulfonic acid, 10-30 parts by mass of hydroxyalkyl acrylate, and 1-10 parts by mass of diene crosslinking monomer.

4. The method according to any one of claims 1 to 3, characterized in that, The diene crosslinking monomer is ethylene glycol diacrylate, divinylbenzene, or a mixture thereof; and / or The mass ratio of the two components in the compound is 1:(0.5~2).

5. The method as described in claim 1, characterized in that, Based on a total mass of 100 parts of the mixed monomer system, the amount of the Span antifogging agent is 5 to 25 parts by mass; the Span antifogging agent is at least one of sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monooleate. The Span-type antifogging agent comprises a combination of two Span-type compounds with different hydrophilic-lipophilic balance values.

6. The method as described in claim 1, characterized in that, The emulsification is carried out at a temperature of 40~60°C, the copolymerization reaction is carried out at 70~90°C for 3~6 hours, and after the copolymerization reaction is completed, a step of heat preservation and maturation at 70~90°C for 1~2 hours is also included.

7. The method as described in claim 1, characterized in that, The Span-type antifogging agent is added to the quaternary copolymer supramolecular matrix by slow dripping over a period of 30-60 minutes, followed by continued heating and stirring for 1-3 hours after the addition is complete.

8. The method as described in claim 1, characterized in that, The functional additives include leveling agents, substrate wetting agents, and adhesion promoters.

9. An anti-fog coating liquid for greenhouse films, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. The application of the anti-fog coating liquid as described in claim 9 to form an anti-fog coating on the surface of polyethylene greenhouse film, ethylene-vinyl acetate copolymer greenhouse film or polyolefin greenhouse film.

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