Low viscosity zero-solvent single-component polyurethane waterproof coating and preparation method thereof

Abstract

The application discloses a kind of low viscosity zero solvent single-component polyurethane waterproof coating and preparation method thereof.The coating includes polyether polyol, toluene diisocyanate, hexamethylene diisocyanate, long-chain chlorinated paraffin functional component, talcum powder, organic bentonite, rutile titanium dioxide, dispersing agent, antioxidant, catalyst and defoaming agent.Long-chain chlorinated paraffin functional component can use side chain hydroxylated long-chain chlorinated paraffin, so that it is connected into polyurethane network by the reaction of hydroxyl and isocyanate group;It can also be added to the double-regulation composite particles composed of porous inorganic core, carbon dioxide capture site, interface coupling layer and non-continuous hydrophobic regulation layer, and further limit the side chain hydroxylated long-chain chlorinated paraffin in the composite particles.The obtained coating has low construction viscosity, low migration, thick coating low pinhole, high bonding strength, and good performance after heat treatment.

Description

Technical Field

[0001] This invention relates to the field of building waterproofing materials technology, specifically to a low-viscosity, solvent-free, single-component polyurethane waterproof coating and its preparation method, which uses a compound system of long-chain chlorinated paraffin functional components, toluene diisocyanate, and hexamethylene diisocyanate. Background Technology

[0002] One-component polyurethane waterproof coatings typically use isocyanate-terminated prepolymers formed by the reaction of polyether polyols and aromatic polyisocyanates as the main film-forming component, combined with plasticizers, pigments, fillers, thixotropic agents, catalysts, and other additives. After application, the isocyanate groups in the system react with ambient moisture to cure and form a film. One-component polyurethane waterproof coatings require no on-site mixing and are characterized by convenient application, integral film formation, good elongation properties, and adaptability to complex substrates. They are widely used for waterproofing roofs, underground projects, kitchens and bathrooms, and irregularly shaped joints.

[0003] Traditional one-component polyurethane waterproof coatings typically add xylene, solvent oil, or other volatile organic solvents to reduce system viscosity and improve application flowability. These organic solvents evaporate during coating application and curing, increasing volatile organic compound emissions and potentially causing film shrinkage, surface defects, and uneven film thickness. Eliminating volatile organic solvents allows the polyurethane prepolymer, inorganic fillers, and thixotropic agents to work together, easily increasing system viscosity and affecting application properties such as scraping, rolling, and leveling. Therefore, solvent-free one-component polyurethane waterproof coatings still need to address the balance between application viscosity and film-forming properties.

[0004] Existing technology CN104194609A discloses a low-VOC environmentally friendly one-component polyurethane waterproof coating. Its raw materials include diphenylmethane diisocyanate, polyether polyol, plasticizer, pigments and fillers, bentonite, defoamer, and catalyst. The plasticizer can be selected from chlorinated paraffin and citrate. The coating is prepared through steps such as dispersion, vacuum dehydration, isocyanate addition reaction, and vacuum degassing, reducing the VOC content of the coating without adding solvents or coal tar. This technology demonstrates that low-VOC one-component polyurethane waterproof coatings can be prepared using polyether polyol, isocyanate, plasticizer, and a high proportion of pigments and fillers.

[0005] Existing technology CN120554943A discloses an environmentally friendly one-component polyurethane waterproof coating and its preparation method. The raw materials include mixed polyols, isocyanates, phosphate nanoparticles, defoamers, and antioxidants; wherein the mixed polyols include block polyether polyols containing catechol structures, polyglycerol ethers, and polyether diols. This technology adjusts the composition of the one-component polyurethane waterproof coating by mixing polyols and nano-components.

[0006] The aforementioned existing technologies mainly improve single-component polyurethane waterproof coatings by reducing volatile organic solvents, adjusting the polyol system, using environmentally friendly plasticizers, or introducing nanofillers. However, for zero-solvent, high-filler systems, further coordination is still needed regarding the relationship between low application viscosity, long-term migration of plasticizer components, gas generation during thick-coat curing, and thickening by inorganic particles.

[0007] Chlorinated paraffins can plasticize, hydrophobize, and reduce viscosity in polyurethane systems. Short-chain chlorinated paraffins have lower molecular weights and a more significant immediate viscosity-reducing effect, but they have stronger diffusion and migration capabilities within the polyurethane network. They are prone to precipitation after prolonged exposure to heat, water immersion, or stress, which can affect coating adhesion and durability. Common long-chain chlorinated paraffins have larger molecular sizes and a relatively lower migration tendency, but they still mainly exist in a physically blended state within the polyurethane system, and long-term migration cannot be completely avoided.

[0008] Furthermore, single-component polyurethanes primarily cure by reacting isocyanate groups with ambient moisture, a reaction that releases carbon dioxide while forming urea bonds. In cases of thick coatings, high substrate moisture content, or high ambient humidity, moisture may concentrate in localized areas of the coating, preventing the generated carbon dioxide from escaping promptly and easily leading to bubbles, pinholes, or internal pores. While directly adding desiccant or a large amount of inorganic particles can alter the moisture distribution in the system, it may excessively consume the moisture required for curing and significantly increase the coating viscosity due to particle agglomeration and increased internal friction.

[0009] Therefore, there is a need to provide a low-viscosity, solvent-free, single-component polyurethane waterproof coating that, without the addition of volatile organic solvents to reduce the viscosity of the system, balances application fluidity, plasticizer stability, thick film quality, substrate adhesion, and long-term durability. Summary of the Invention

[0010] The purpose of this invention is to provide a low-viscosity, solvent-free, single-component polyurethane waterproof coating and its preparation method, in order to solve the problems of high application viscosity, easy migration and precipitation of chlorinated paraffin plasticizers, and the generation of bubbles and pinholes during curing under thick coating or humid conditions in solvent-free, high-filler single-component polyurethane waterproof coatings.

[0011] This invention improves coating durability while maintaining the application fluidity of a solvent-free system by employing low hydroxyl value, high molecular weight polyether polyol, TDI and HDI compounded isocyanate system, and long-chain chlorinated paraffin. Furthermore, by side-chain hydroxylation of the long-chain chlorinated paraffin, it partially participates in the formation of the polyurethane network. Finally, through moisture-carbon dioxide dual-regulation of the interface, the composite particles and the confined structure formed with the side-chain hydroxylated long-chain chlorinated paraffin are enhanced, thereby improving the quality of thick coating film formation, the migration stability of plasticizer components, and interfacial adhesion.

[0012] Technical solution To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a low-viscosity, solvent-free, single-component polyurethane waterproof coating, comprising, by weight, 20-30 parts of polyether polyol, 3-4 parts of toluene diisocyanate, 1-2 parts of hexamethylene diisocyanate, 5-10 parts of long-chain chlorinated paraffin, 0.2-0.3 parts of dispersant, 30-40 parts of talc, 0.8-1.5 parts of organobentonite, 3-10 parts of rutile titanium dioxide, 0.5-1.0 parts of antioxidant, 0.1-0.2 parts of catalyst, and 0.1-0.4 parts of defoamer.

[0013] The long-chain chlorinated paraffin is a long-chain chlorinated paraffin with an average carbon chain length of C18~C30 and a chlorine content of 40~55wt%.

[0014] This invention employs long-chain chlorinated paraffins to plasticize and regulate the viscosity of polyurethane systems. Compared to short-chain chlorinated paraffins, long-chain chlorinated paraffins have larger molecular sizes, longer diffusion paths within the polyurethane network, and are subject to greater polymer chain entanglement and steric hindrance. Therefore, while maintaining plasticization and workability, they can reduce the tendency for thermal effects and migration / precipitation during long-term use.

[0015] The waterproof coating is prepared without the addition of any volatile organic solvents to reduce the viscosity of the system. "Zero solvent" means that xylene, trimethylbenzene, solvent oil, acetate, or other volatile organic solvents are not used as diluents or viscosity-reducing components, but trace amounts of unavoidable volatile substances introduced during raw material production or by the additives themselves are not excluded.

[0016] Preferably, the polyether polyol is a DL-4000 type polyether diol with a hydroxyl value of 26~30 mgKOH / g and a number-average molecular weight of 3500~4500.

[0017] DL-4000 polyether diol has a high molecular weight and a low hydroxyl value. Under the same mass conditions, it contains a low hydroxyl equivalent, which can reduce the density of urethane hard segments formed in the prepolymerization stage, avoid the system viscosity from rising too quickly, and help maintain the flexibility and elongation of the coating film.

[0018] Preferably, the mass ratio of toluene diisocyanate to hexamethylene diisocyanate is 1.5:1 to 4:1.

[0019] Toluene diisocyanate (TBD) exhibits high reactivity, which is beneficial for prepolymerization and the formation of the initial network in the coating film. Hexamethylene diisocyanate (HDI) forms aliphatic segments with good flexibility and thermal stability. The combination of these two components at the stated mass ratio avoids the slow initial network formation caused by an excessively high HDI proportion, and also reduces the hard segment concentration and post-heat treatment performance degradation caused by an excessively high toluene diisocyanate proportion, thus achieving a balance between application viscosity, bond strength, and heat treatment performance.

[0020] Preferably, the water content of the waterproof coating is not higher than 0.05 wt%, and the isocyanate group content is 1.9~2.5 wt%.

[0021] Controlling the moisture content of the coating to no more than 0.05 wt% can reduce the risk of viscosity increase, skinning, and gas generation caused by premature reaction between moisture and isocyanate groups during packaging and storage. Controlling the isocyanate group content to 1.9~2.5 wt% can retain the active isocyanate groups required for subsequent moisture curing, while avoiding excessive isocyanate group content that can lead to a hard coating film, increased gas generation, or high levels of free isocyanate residue.

[0022] Furthermore, the long-chain chlorinated paraffin is a side-chain hydroxylated long-chain chlorinated paraffin, which has a hydroxyl-containing ether bond side chain grafted onto the long-chain chlorinated alkyl structure, with a hydroxyl value of 8~25mgKOH / g and a moisture content of not more than 0.05wt%.

[0023] Side-chain hydroxylated long-chain chlorinated paraffins retain the plasticizing, hydrophobic, and compatibility properties of long-chain chlorinated paraffins, while introducing hydroxyl groups capable of reacting with isocyanate groups into their side chains. During the prepolymerization reaction and subsequent moisture curing process, at least some of the side-chain hydroxyl groups form urethane bonds with the isocyanate groups, chemically constraining the long-chain chlorinated alkyl structure within the polyurethane network and reducing the likelihood of its migration and precipitation as a free plasticizer component. Controlling the hydroxyl value to 8–25 mg KOH / g balances chemical fixation and application viscosity.

[0024] Furthermore, the waterproof coating also includes 1 to 6 parts by weight of moisture-carbon dioxide dual-regulated interface-enhanced composite particles.

[0025] The moisture-carbon dioxide dual-regulated interface-enhanced composite particles include a porous silica core, magnesium oxide and / or calcium oxide loaded in the pores and / or pore openings of the porous silica core, an interface coupling layer disposed on the surface of the porous silica core, and a discontinuous hydrophobic regulation layer disposed on the outer surface of the porous silica core.

[0026] The porous silica core has a channel structure that can temporarily adsorb and buffer moisture entering the coating from the environment or a damp substrate, reducing the degree of localized moisture concentration and rapid reaction with isocyanate groups. This moisture buffering effect does not completely isolate curing moisture, but rather changes the instantaneous distribution and migration rate of moisture in the coating, making the moisture curing reaction relatively uniform.

[0027] The magnesium oxide and / or calcium oxide are disposed within the pores and / or at the openings of the porous silica, enabling the adsorption and / or fixation of some of the carbon dioxide formed during the curing process. Loading them inside the pores reduces the direct agglomeration of alkaline inorganic particles in the coating and allows carbon dioxide to enter the pores and contact the oxides, thereby reducing the probability of bubble coalescence and the formation of through-holes.

[0028] The interfacial coupling layer is formed by the condensation of an epoxy-based silane coupling agent with silanol groups on the surface of porous silica after hydrolysis. The silane ends of the epoxy-based silane are bonded to the surface of porous silica, and the exposed organic functional structure can improve the compatibility between the composite particles and the polyurethane organic phase, and improve the interfacial bonding of the composite particles near inorganic substrates such as concrete and mortar.

[0029] The discontinuous hydrophobic control layer is formed from C8-C16 alkylsilanes. The discontinuous hydrophobic control layer can reduce the tendency of composite particles to continuously absorb moisture from the environment during storage and reduce premature reactions in the coating packaging state; at the same time, since it does not form a completely closed continuous coating layer, it still retains the migration channels for moisture and carbon dioxide to enter the porous silica channels.

[0030] Based on 100 parts by weight of the porous silica, the content of magnesium oxide and / or calcium oxide is 10-30 parts, the amount of epoxy silane coupling agent is 1-5 parts, and the amount of C8-C16 alkyl silane is 0.5-3 parts.

[0031] Furthermore, the side-chain hydroxylated long-chain chlorinated paraffin and the water-carbon dioxide dual-regulated interface-enhanced composite particles are added in the form of pre-prepared confined hydroxylated long-chain chlorinated paraffin dual-regulated composite particles.

[0032] The mass ratio of the side-chain hydroxylated long-chain chlorinated paraffin to the moisture-carbon dioxide dual-regulated interface-enhanced composite particles is 1:0.4 to 1:1. At least a portion of the side-chain hydroxylated long-chain chlorinated paraffin enters the channels and / or pores of the porous silica core.

[0033] The side-chain hydroxylated long-chain chlorinated paraffins entering the pore and pore opening regions are restricted by the tortuous path of the pores, capillary action, and pore obstruction, increasing their migration path and steric resistance, thus forming physical confinement. The side-chain hydroxyl groups located at the pore openings and on the outer surface of the particles can also react with isocyanate groups, further fixing the confined structure within the polyurethane network. The combined effect of this physical confinement and chemical fixation reduces the migration of plasticizer components.

[0034] The side-chain hydroxylated long-chain chlorinated paraffin in the confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particles is included in the amount of long-chain chlorinated paraffin, and the moisture-carbon dioxide dual-regulation interface-enhanced composite particles are included in the amount of composite particles.

[0035] On the other hand, the present invention also provides a method for preparing the above-mentioned low-viscosity, solvent-free, single-component polyurethane waterproof coating, comprising the following steps.

[0036] S1, Predispersion Polyether polyol, long-chain chlorinated paraffin and dispersant are added to a dispersion vessel and heated to above 90°C while stirring. Then, organic bentonite, rutile titanium dioxide and talc are added and dispersed at 105~120°C for 20~40 min to obtain a pre-dispersed mixture.

[0037] Adding organobentonite and pigments / fillers at temperatures above 90℃ can reduce the viscosity of polyether polyols and long-chain chlorinated paraffins, promoting the wetting of the filler surface by the dispersant. Controlling the dispersion temperature at 105~120℃ can improve the dispersion uniformity of organobentonite, rutile titanium dioxide, and talc, while avoiding oxidation of polyether polyols or decomposition of additives due to excessively high temperatures.

[0038] When preparing a waterproof coating containing moisture-carbon dioxide dual-regulated interface-enhanced composite particles, the composite particles are added in the pre-dispersion step to disperse them together with organic bentonite, titanium dioxide and talc.

[0039] When preparing a confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particle system, the confined composite particles are added in step S1 as a co-addition of side-chain hydroxylated long-chain chlorinated paraffin and water-carbon dioxide dual-regulation interface-enhancing composite particles.

[0040] S2, Grinding and Dehydration The pre-dispersed mixture is ground in a colloid mill and then introduced into a dehydration kettle. It is dehydrated for 1.5 to 2.5 hours at 117 to 123°C and -95 kPa to -90 kPa pressure until the moisture content of the mixture is no higher than 0.05 wt%.

[0041] Colloid milling can further break down soft agglomerates of pigments, fillers, and composite particles, ensuring uniform particle distribution in the liquid phase. Removing moisture introduced by polyether polyols, fillers, and additives through a combination of high temperature and vacuum reduces premature reaction and gas generation when isocyanates are subsequently added. Controlling the dehydration pressure to -95kPa to -90kPa improves moisture removal efficiency at lower temperatures and reduces the risk of material oxidation caused by prolonged high-temperature processing.

[0042] S3, Prepolymerization Reaction Cool the dehydrated mixture to below 80°C, add toluene diisocyanate dropwise first, then add hexamethylene diisocyanate dropwise, and react at 77~83°C for 2~3 hours until the isocyanate group content in the system reaches 1.9~2.5wt%.

[0043] Adding toluene diisocyanate, which has high reactivity, first facilitates the formation of the prepolymer backbone with the hydroxyl groups of the polyether polyol. Then, adding hexamethylene diisocyanate helps control the reaction rate and introduces the aliphatic structure into the prepolymer system. Stepwise addition reduces the viscosity spikes and side reactions caused by excessively high local isocyanate concentrations.

[0044] When the system contains side-chain hydroxylated long-chain chlorinated paraffins, the side-chain hydroxyl groups react with some isocyanate groups in this step, causing the long-chain chlorinated alkyl structure to be constrained by the polyurethane prepolymer network.

[0045] S4, Post-processing Antioxidant, catalyst and defoamer are added, and the reaction continues for 0.3~0.7h. Then the temperature is lowered to below 70℃, and the product is sealed and packaged to obtain the low viscosity solvent-free single-component polyurethane waterproof coating.

[0046] Antioxidants are used to reduce oxidative aging of coatings during storage and application; catalysts are used to regulate the curing reaction rate of isocyanate groups with ambient moisture after application; defoamers are used to reduce mechanical bubbles introduced during pre-dispersion, grinding, and prepolymerization. Sealing the packaging after cooling to below 70°C reduces moisture absorption and internal pressure increases caused by high-temperature packaging.

[0047] Preferably, when preparing a waterproof coating containing side-chain hydroxylated long-chain chlorinated paraffins, the following steps are included before step S1: 100 parts by mass of long-chain chlorinated paraffin were heated to 115-135°C, and 3-8 parts by mass of glycidyl methacrylate and 0.1-0.4 parts by mass of peroxide initiator were added under an inert atmosphere to carry out a free radical grafting reaction for 1-3 hours to obtain long-chain chlorinated paraffin containing epoxy side chains.

[0048] An inert atmosphere can reduce the inhibitory effect of oxygen on polymerization during free radical reactions. The unsaturated double bonds in glycidyl methacrylate are used to form grafted side chains, while the epoxy groups serve as reaction sites for the subsequent formation of hydroxyl ether side chains. Adding glycidyl methacrylate dropwise helps reduce local monomer concentration and minimizes monomer self-polymerization.

[0049] The long-chain chlorinated paraffin containing epoxy side chains is reacted with 2-6 parts by mass of a monohydric alcohol and 0.03-0.15 parts by mass of a ring-opening catalyst at 90-110°C for 1-2 hours to cause the epoxy side chains to undergo a ring-opening reaction, forming side chains containing hydroxyl ether bonds.

[0050] After the monohydric alcohol ring-opens the epoxy group, ether bonds and hydroxyl groups are formed in the grafted side chain. The formed hydroxyl groups provide active sites for subsequent reactions with isocyanate groups, while the ether bonds can maintain a certain degree of flexibility in the side chain, avoiding excessive rigidity of the modified long-chain chlorinated paraffin.

[0051] After the reaction is complete, vacuum devolatilization and dehydration are performed to obtain side-chain hydroxylated long-chain chlorinated paraffins with a hydroxyl value of 8~25 mgKOH / g and a moisture content of no more than 0.05 wt%.

[0052] Vacuum devolatilization is used to reduce the content of unreacted small molecules and moisture, thereby reducing their impact on subsequent isocyanate prepolymerization reactions and product storage stability.

[0053] Preferably, when using confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particles, the following steps are included before step S1: The side-chain hydroxylated long-chain chlorinated paraffin and the water-carbon dioxide dual-regulated interface-enhanced composite particles were mixed at a mass ratio of 1:0.4 to 1:1 and kept at 70 to 95°C and -90 kPa to -80 kPa pressure for 20 to 60 minutes, and then restored to normal pressure.

[0054] Under heated conditions, the viscosity of side-chain hydroxylated long-chain chlorinated paraffins decreases; vacuum conditions can expel the gas from the porous silica channels, and the pressure difference generated after restoring normal pressure promotes the side-chain hydroxylated long-chain chlorinated paraffins to enter the channels.

[0055] Repeat the vacuum-atmospheric pressure cycle 2 to 4 times to allow at least some of the side-chain hydroxylated long-chain chlorinated paraffins to enter the pores and / or pore openings of the water-carbon dioxide dual-regulated interface enhanced composite particles.

[0056] Subsequently, the particles were vacuum treated for 20-60 minutes at 90-110℃ and -95kPa to -80kPa pressure to remove moisture and volatile small molecules that may have been introduced during the confinement process, and to promote the stable distribution of side-chain hydroxylated long-chain chlorinated paraffin in the channels and pore openings, thus obtaining the confinement-type hydroxylated long-chain chlorinated paraffin dual-regulated composite particles.

[0057] The preparation method of the moisture-carbon dioxide dual-regulated interface-enhanced composite particles is as follows: Porous silica is immersed in an aqueous solution of magnesium nitrate and / or calcium nitrate, and vacuum impregnated for 10 to 40 minutes under a pressure of -95 kPa to -80 kPa, so that magnesium nitrate and / or calcium nitrate enter the channels and / or openings of the porous silica.

[0058] Under vacuum, the gas in the porous silica channels is expelled; after the pressure is restored, the impregnation solution containing magnesium and / or calcium enters the channels and orifice regions, thereby reducing the situation where the precursor is deposited only on the outer surface of the particles.

[0059] The impregnated porous silica is dried at 100~130℃ and then heat-treated at 450~650℃ for 1~3 hours to convert magnesium nitrate and / or calcium nitrate into magnesium oxide and / or calcium oxide.

[0060] When magnesium nitrate is used, the heat treatment temperature is preferably 450~550℃; when calcium nitrate is used, the heat treatment temperature is preferably 550~650℃; when both are used, the heat treatment temperature is preferably 550~620℃. Magnesium oxide and / or calcium oxide are loaded into the porous silica channels and pore openings through thermal decomposition.

[0061] A porous silica loaded with magnesium oxide and / or calcium oxide is surface-treated with an epoxy-based silane coupling agent, which hydrolyzes and then condenses with the silanol groups on the surface of the porous silica to form an interfacial coupling layer.

[0062] Then, C8~C16 alkylsilanes are used for incomplete hydrophobic treatment to form a discontinuous hydrophobic control layer on the outer surface of the porous silica.

[0063] By controlling the amount of alkylsilane used to form a discontinuous hydrophobic structure, the moisture absorption rate of the composite particles during packaging can be reduced without completely sealing the pores. After drying, pulverizing, and sieving, moisture-carbon dioxide dual-regulated interface-reinforced composite particles with a moisture content not exceeding 0.15 wt% are obtained. Beneficial effects

[0064] The beneficial effects of adopting the technical solution of the present invention are as follows: This invention maintains a suitable application viscosity for both scraping and rolling by combining DL-4000 polyether diol, TDI and HDI compound system, and long-chain chlorinated paraffin without adding volatile organic solvents to reduce system viscosity.

[0065] Using long-chain chlorinated paraffins can reduce migration, precipitation, and heat treatment performance degradation compared to short-chain chlorinated paraffins. After side-chain hydroxylation of long-chain chlorinated paraffins, some long-chain chlorinated alkyl structures can be chemically constrained by the polyurethane network, further improving the stability of the plasticizer.

[0066] The moisture-carbon dioxide dual-regulation interface-enhanced composite particles can buffer the moisture entering the coating film and adsorb and / or fix some of the carbon dioxide generated by the curing reaction, thereby reducing bubbles and pinholes in thick coatings; the interface coupling layer can also improve the bonding between the composite particles and the polyurethane matrix and inorganic substrate.

[0067] By confining side-chain hydroxylated long-chain chlorinated paraffins to the pore and orifice regions of dual-regulated interface-reinforced composite particles, a combination of physical confinement and chemical fixation is achieved, resulting in a comprehensive balance between low application viscosity, low plasticizer migration, low thick-coat pinholes, and high bond strength. Attached Figure Description

[0068] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0069] Figure 1 This is a flowchart of the coating preparation method improved by the present invention using confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particles. Detailed Implementation

[0070] The following embodiments are used to further illustrate the present invention, but do not constitute a limitation on the scope of protection. Unless otherwise specified, all "parts" refer to parts by weight. The same batch of raw materials, layer thickness, coating amount, and test conditions were used in the same comparative group, with only the explicitly stated technical variables changed. Example 1

[0071] This embodiment provides a low-viscosity, solvent-free, one-component polyurethane waterproof coating, comprising, by weight: 25 parts of polyether polyol DL-4000, 3 parts of toluene diisocyanate, 2 parts of hexamethylene diisocyanate, 7.5 parts of long-chain chlorinated paraffin with an average carbon chain length of C20~C24 and a chlorine content of 48wt%, 0.25 parts of dispersant, 35 parts of talc, 1.2 parts of pre-activated organobentonite, 5 parts of rutile titanium dioxide, 0.7 parts of antioxidant 1010, 0.15 parts of organobismuth catalyst, and 0.3 parts of polyether-modified siloxane defoamer.

[0072] The mass ratio of toluene diisocyanate to hexamethylene diisocyanate is 1.5:1.

[0073] Its preparation method is as follows: S1. Add polyether polyol DL-4000, long-chain chlorinated paraffin and dispersant to a dispersion vessel, and heat to 95°C at a stirring frequency of 25Hz; then slowly add organobentonite, rutile titanium dioxide and talc, increase the stirring frequency to 30Hz, and disperse at 115°C for 30 min to obtain a pre-dispersed mixture.

[0074] S2. After grinding the pre-dispersed mixture in a colloid mill, it is introduced into a dehydration kettle and dehydrated at 120℃ and -90kPa for 2 hours until the moisture content of the mixture is not higher than 0.05wt%.

[0075] S3. Cool the dehydrated mixture to 78°C, add toluene diisocyanate dropwise first, then add hexamethylene diisocyanate dropwise. After the addition is complete, react at 80°C for 2.5 hours until the isocyanate group content in the system reaches 2.4 wt%.

[0076] S4. Add antioxidant, organic bismuth catalyst and defoamer, continue the reaction for 0.5h, then cool to 65℃ and seal the package.

[0077] No additional volatile organic solvents are added during the preparation process to reduce the viscosity of the system. Example 2

[0078] This embodiment is basically the same as Embodiment 1, except that: The amount of toluene diisocyanate used is 3.5 parts, and the amount of hexamethylene diisocyanate used is 1.5 parts, with a mass ratio of 2.33:1.

[0079] The total amount of toluene diisocyanate and hexamethylene diisocyanate used was still 5 parts, and the other raw materials and preparation conditions were the same as in Example 1. Example 3

[0080] This embodiment is basically the same as Embodiment 2, except that: Replace 7.5 parts of ordinary long-chain chlorinated paraffin with 7.5 parts of side-chain hydroxylated long-chain chlorinated paraffin A.

[0081] The side-chain hydroxylated long-chain chlorinated paraffin A was prepared in this embodiment according to the following method: 100 parts of long-chain chlorinated paraffin with an average carbon chain length of C20~C24 and a chlorine content of 48wt% were added to a reaction vessel, nitrogen gas was introduced and the temperature was raised to 125℃; 6 parts of glycidyl methacrylate and 0.25 parts of dicumyl peroxide were mixed and added dropwise to the reaction vessel over 60 min. After the addition was completed, the reaction was continued for 2 h to obtain long-chain chlorinated paraffin containing epoxy side chains.

[0082] The system was cooled to 102°C, and 4 parts of 2-ethylhexanol and 0.08 parts of tetrabutylammonium bromide were added. The reaction was carried out at 102°C for 1.5 h to allow the epoxy groups on the grafted side chains to undergo a ring-opening reaction, forming side chains containing hydroxyl ether bonds.

[0083] After the reaction was completed, the product was vacuum devolatilized and dehydrated for 1 hour at 100℃ and -95kPa to obtain a side-chain hydroxylated long-chain chlorinated paraffin A with a hydroxyl value of 15.2 mgKOH / g and a moisture content of 0.03 wt%.

[0084] The obtained side-chain hydroxylated long-chain chlorinated paraffin A was added to the waterproof coating at a ratio of 7.5 parts, and the other raw materials and preparation conditions were the same as in Example 2. Example 4

[0085] This embodiment is basically the same as Example 2, except that toluene diisocyanate is 3.5 parts and hexamethylene diisocyanate is 1.5 parts.

[0086] The difference lies in the fact that confined composite particles are pre-prepared using side-chain hydroxylated long-chain chlorinated paraffin A and moisture-carbon dioxide dual-regulated interface-enhanced composite particles B. The complete process is described in [reference needed]. Figure 1 As shown.

[0087] The side-chain hydroxylated long-chain chlorinated paraffin A was prepared according to the method of Example 3.

[0088] The moisture-carbon dioxide dual-regulated interface-enhanced composite particle B was prepared in this embodiment using the following method: Eighty samples were taken with a median particle size D50 of 5 μm and a pore volume of 1.8 cm³. 3 / g of porous silica, magnesium nitrate (equivalent to 12 parts magnesium oxide) and calcium nitrate (equivalent to 3 parts calcium oxide) are dissolved in deionized water to obtain an impregnation solution.

[0089] Porous silica was immersed in the impregnation solution and vacuum impregnated for 30 minutes under -90 kPa conditions. After being restored to normal pressure, it was left to stand for 1 hour. Subsequently, it was dried at 110°C for 4 hours and heat-treated at 600°C for 2 hours to convert magnesium nitrate and calcium nitrate into magnesium oxide and calcium oxide, respectively.

[0090] After cooling, 3 parts of γ-glycidoxypropyltrimethoxysilane were added for surface treatment, which caused it to hydrolyze and then undergo a condensation reaction with the silanol groups on the surface of porous silica. Then, 2 parts of octyltriethoxysilane were added for incomplete hydrophobic treatment. After drying, pulverizing and sieving, dual-regulated interface-enhanced composite particles B were obtained.

[0091] Based on the mass fraction of the final waterproof coating, take 7.86 parts of side-chain hydroxylated long-chain chlorinated paraffin A and 3.14 parts of dual-regulated interface-reinforced composite particles B, with a mass ratio of 1:0.4, and a total amount of 11 parts.

[0092] The two were mixed at 85°C and kept under a pressure of -85 kPa for 40 min. The mixture was then restored to atmospheric pressure and stirred for another 10 min. The vacuum-atmospheric pressure cycle was repeated three times to allow at least some of the side-chain hydroxylated long-chain chlorinated paraffin A to enter the channels and pores of the composite particles B.

[0093] Subsequently, the particles were vacuum-treated at 100℃ and -85kPa for 45 minutes to obtain confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particles.

[0094] The 11 confined composite particles obtained were added in step S1 as a combination of side-chain hydroxylated long-chain chlorinated paraffin and dual-regulated interface-enhanced composite particles. Other raw materials and preparation conditions were the same as in Example 2. Example 5

[0095] This embodiment is basically the same as embodiment 4, except that: Based on the final waterproof coating mass fraction, take 5.5 parts of side-chain hydroxylated long-chain chlorinated paraffin A and 5.5 parts of moisture-carbon dioxide dual-regulated interface-enhanced composite particles B, with a total usage of 11 parts.

[0096] Both were pre-prepared into confined composite particles according to the vacuum-atmospheric pressure cycling method of Example 4, and added in step S1.

[0097] The other raw materials, dosages, and preparation conditions are the same as in Example 4. Comparative Example 1

[0098] This comparative example is basically the same as Example 2, except that: The amount of toluene diisocyanate used was 2.8 parts, and the amount of hexamethylene diisocyanate used was 2.2 parts, with a mass ratio of 1.27:1.

[0099] The total amount of toluene diisocyanate and hexamethylene diisocyanate used was still 5 parts, and the other raw materials and preparation conditions were the same as in Example 2. Comparative Example 2

[0100] This comparative example is basically the same as Example 2, except that: The amount of toluene diisocyanate used is 4.2 parts, and the amount of hexamethylene diisocyanate used is 0.8 parts, with a mass ratio of 5.25:1.

[0101] The total amount of toluene diisocyanate and hexamethylene diisocyanate used was still 5 parts, and the other raw materials and preparation conditions were the same as in Example 2. Comparative Example 3

[0102] This comparative example is basically the same as Example 2, except that: Replace 7.5 parts of long-chain chlorinated paraffin with an average carbon chain length of C20~C24 with 7.5 parts of short-chain chlorinated paraffin with an average carbon chain length of C10~C13 and a chlorine content of 48wt%.

[0103] The other raw materials, dosages, and preparation conditions are the same as in Example 2. Comparative Example 4

[0104] This comparative example is basically the same as Example 4, except that: Based on the final waterproof coating mass fraction, take 8.8 parts of side-chain hydroxylated long-chain chlorinated paraffin A and 2.2 parts of moisture-carbon dioxide dual-regulated interface-enhanced composite particles B, with a total usage of 11 parts.

[0105] Both were pre-prepared into confined composite particles using the vacuum-atmospheric pressure cycling method of Example 4, with other raw materials, amounts, and preparation conditions being the same as in Example 4. Comparative Example 5

[0106] This comparative example is basically the same as Example 5, except that: Based on the mass fraction of the final waterproof coating, take 5 parts of side-chain hydroxylated long-chain chlorinated paraffin A and 6 parts of moisture-carbon dioxide dual-regulated interface-enhanced composite particles B, with a total usage of 11 parts.

[0107] Both were pre-prepared into confined composite particles using the vacuum-atmospheric pressure cycling method of Example 4, with other raw materials, amounts, and preparation conditions being the same as in Example 5.

[0108] Performance testing and characterization Test method: 1. Initial viscosity The sample was kept at 25±1℃ for 2 hours, and the initial viscosity was tested using a rotational viscometer under the same rotor and rotational speed conditions.

[0109] The lower the initial viscosity, the better the coating has in terms of application flowability without the addition of volatile organic solvents.

[0110] 2. Bond strength The waterproof coating was applied to the concrete substrate, and the film thickness was controlled to be uniform. After curing under standard conditions, the tensile bond strength between the coating and the concrete substrate was tested.

[0111] 3. Heat treatment tensile strength retention rate The standard coating was heat-treated at 80℃ for 168 hours, and the tensile strength before and after heat treatment was tested and calculated using the following formula: Heat treatment tensile strength retention rate = (Tensile strength after heat treatment / Tensile strength before heat treatment) × 100% 4. Analysis yield of the plasticizer group Take a coating film of the same size and thickness, place it at 70℃ and under specified compressive stress for 168 hours, collect the plasticizing components precipitated from the coating film using oil-absorbing filter paper, and calculate the precipitation rate based on the increase in the mass of the filter paper.

[0112] 5. Number of pinholes in thick coating A 2.0±0.1 mm thick wet film was coated onto a glass plate and cured for 7 days at 23±2℃ and 50±10% relative humidity. The film was then observed at a depth of 100 cm using transmitted light. 2 The number of pinholes with a diameter greater than 0.1 mm within the range.

[0113] The performance of the samples from Examples 1-5 and Comparative Examples 1-5 was tested, and the test results are shown in the table below:

[0114]

[0115] Test Result Analysis: The initial viscosity at 25°C for Examples 1 and 2 was below 12000 mPa·s, and the adhesion strength and heat treatment tensile strength retention rates were relatively stable. This indicates that, without the addition of additional volatile organic solvents, the use of TDI and HDI within a limited range can balance the coating's application viscosity, substrate adhesion performance, and the retention of mechanical properties after heat treatment.

[0116] In Comparative Example 1, when the relative amount of HDI exceeded the limit, the initial viscosity of the coating decreased slightly, but the bond strength decreased, and the number of pinholes in the thick coating increased. In Comparative Example 2, when the relative amount of TDI exceeded the limit, the bond strength remained at a high level, but the retention rate of heat-treated tensile strength decreased, and the plasticizer exudation rate and the number of pinholes in the thick coating increased. This shows that the mixing ratio of TDI and HDI does not only affect a single property; limiting the amount and mass ratio of both can achieve a good overall balance between reactivity, flexibility, thermal stability, migration stability, and the quality of thick coating film formation.

[0117] In Comparative Example 3, the initial viscosity decreased to 7000 mPa·s after using short-chain chlorinated paraffin, but the plasticizer precipitation rate increased to 4.80%, and the retention rates of bond strength and heat-treated tensile strength were significantly reduced, while the number of pinholes in the thick coating also increased. The results indicate that although short-chain chlorinated paraffin has strong immediate plasticizing and viscosity-reducing effects, its smaller molecular size and stronger migration ability within the polyurethane network make it more prone to precipitation and performance degradation under long-term thermal exposure. Using long-chain chlorinated paraffin can maintain the low viscosity and workability of the coating while reducing plasticizer migration and improving the adhesion and durability of the coating film.

[0118] In Example 3, after side-chain hydroxylation of long-chain chlorinated paraffin, the initial viscosity increased from 8200 mPa·s to 9000 mPa·s, but remained within the preset low viscosity range. Simultaneously, the plasticizer concentration decreased from 2.70% to 1.05%, and both bond strength and heat-treated tensile strength retention improved. These results indicate that the main effect of side-chain hydroxylation is not to further reduce the system viscosity, but rather to reduce the migration tendency of long-chain chlorinated paraffin while maintaining an applicable viscosity. The side-chain hydroxyl groups can react with isocyanate groups during prepolymerization or subsequent moisture curing, chemically binding some long-chain chlorinated alkyl structures to the polyurethane network, thereby improving the migration stability and structural stability of the coating film.

[0119] Examples 4 and 5, based on side-chain hydroxylated long-chain chlorinated paraffin, introduced moisture-carbon dioxide dual-regulated interface-reinforced composite particles, and formed confined composite particles through vacuum-atmospheric pressure cycling. Compared with Example 3, Examples 4 and 5 showed further reductions in the plasticizer content and the number of pinholes in the thick coating, while improving the retention rate of bond strength and heat-treated tensile strength. Simultaneously, the initial viscosity of the coating increased with the increase of the proportion of dual-regulated interface-reinforced composite particles. This change aligns with the physicochemical principles that porous inorganic particles thicken the system while providing physical confinement, moisture buffering, carbon dioxide regulation, and interfacial coupling effects.

[0120] Among these components, porous silica can temporarily adsorb and buffer moisture entering the coating, reducing the degree of concentrated reaction between local moisture and isocyanate groups. Magnesium oxide and calcium oxide loaded in the channels and at the pore openings can adsorb or fix some of the carbon dioxide generated during the curing process, thereby reducing the formation of bubbles and pinholes inside the thick coating film. The interfacial coupling layer formed by epoxy-based silanes can improve the interfacial bonding between the composite particles and the polyurethane matrix and concrete substrate. After the side-chain hydroxylated long-chain chlorinated paraffins enter the channels and pore openings of the porous particles, their migration path and steric resistance increase, and they can be further chemically fixed through the reaction of side-chain hydroxyl groups with isocyanate groups.

[0121] In Comparative Example 4, the mass ratio of side-chain hydroxylated long-chain chlorinated paraffin A to dual-regulation interface-reinforced composite particles B was less than 1:0.4. Although the coating viscosity was lower, the plasticizer content and the number of pinholes in the thick coating were higher than in Example 4, and the bonding strength was also reduced. This indicates that when the relative amount of composite particles is too small, the pore space available for side-chain hydroxylated long-chain chlorinated paraffin to enter and the sites for action for moisture buffering and carbon dioxide regulation are insufficient, and the confinement and dual-regulation effects cannot be fully utilized.

[0122] In Comparative Example 5, the mass ratio of side-chain hydroxylated long-chain chlorinated paraffin A to dual-regulated interface-reinforced composite particles B was higher than 1:1. While the plasticizer concentration remained low, the initial viscosity of the coating increased to 12400 mPa·s, exceeding the preset low viscosity range. This resulted in decreased bonding strength and a slight increase in the number of pinholes in the thick coating. This indicates that when the relative dosage of the dual-regulated interface-reinforced composite particles is too high, the side-chain hydroxylated long-chain chlorinated paraffin is insufficient to fully wet the surface of all inorganic particles. Increased contact, friction, and agglomeration between particles lead to thickening of the system and uneven local film formation.

[0123] In summary, this invention achieves lower application viscosity by using long-chain chlorinated paraffins without the addition of volatile organic solvents, and reduces migration, precipitation, and heat treatment performance degradation compared to short-chain chlorinated paraffins. By side-chain hydroxylation of the long-chain chlorinated paraffins, they partially participate in the formation of the polyurethane network, further improving migration stability and adhesion. Furthermore, the introduction and confinement of moisture-carbon dioxide dual-regulated interface-reinforced composite particles further improves the quality of thick-coat film formation, substrate adhesion, and coating durability. By controlling the mass ratio of side-chain hydroxylated long-chain chlorinated paraffins to the dual-regulated interface-reinforced composite particles within a specified range, a good overall balance can be achieved between low-viscosity application, low migration and precipitation, low thick-coat pinholes, and high adhesion strength.

[0124] The low-viscosity, solvent-free, single-component polyurethane waterproof coating of this invention can be prepared continuously or in batches using conventional dispersion, colloid milling, vacuum dehydration, isocyanate dropwise prepolymerization, post-treatment, and sealed filling equipment. The raw materials are readily available, the process steps are mature, and process parameters such as temperature, vacuum level, moisture content, and isocyanate group content are easily controlled, making it suitable for industrial-scale production. The resulting waterproof coating can be applied by scraping, rolling, or spraying, and is suitable for waterproofing or repairing concrete, mortar, tiles, old waterproof layers, corrugated steel sheets, pipe roots, internal and external corners, and irregular joints, demonstrating excellent value for industrial production and engineering construction applications.

[0125] 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 low-viscosity, solvent-free, one-component polyurethane waterproof coating, characterized in that: By weight, it includes: 20-30 parts of polyether polyol, 3-4 parts of toluene diisocyanate 1-2 parts of hexamethylene diisocyanate 5-10 parts of long-chain chlorinated paraffins. Dispersant 0.2~0.3 parts, 30-40 parts talcum powder 0.8-1.5 parts organic bentonite, 3-10 parts of rutile titanium dioxide Anti-aging agent 0.5~1.0 parts, Catalyst 0.1~0.2 parts, Defoamer 0.1~0.4 parts; The long-chain chlorinated paraffin is a long-chain chlorinated paraffin with an average carbon chain length of C18~C30 and a chlorine content of 40~55wt%. No additional volatile organic solvents are added during the preparation of the waterproof coating to reduce the viscosity of the system.

2. The waterproof coating according to claim 1, characterized in that: The polyether polyol is DL-4000 type polyether diol with a hydroxyl value of 26~30mgKOH / g and a number-average molecular weight of 3500~4500. The waterproof coating has a moisture content of no more than 0.05 wt%, an isocyanate group content of 1.9~2.5 wt%, and a mass ratio of toluene diisocyanate to hexamethylene diisocyanate of 1.5:1~4:

1.

3. The waterproof coating according to claim 1, characterized in that: The long-chain chlorinated paraffin is a side-chain hydroxylated long-chain chlorinated paraffin. The side-chain hydroxylated long-chain chlorinated paraffin has a hydroxyl-containing ether bond side chain grafted onto the long-chain chlorinated alkyl structure. Its hydroxyl value is 8~25mgKOH / g and its moisture content is not higher than 0.05wt%.

4. The waterproof coating according to claim 3, characterized in that: It also includes 1-6 parts by weight of moisture-carbon dioxide dual-regulation interface-enhanced composite particles; the composite particles include: Porous silica core; Magnesium oxide and / or calcium oxide loaded in the channels and / or at the openings of the porous silica core; An interface coupling layer disposed on the surface of the porous silica core, the interface coupling layer being formed by the condensation of an epoxy-based silane coupling agent with silanol groups on the surface of the porous silica after hydrolysis; and A discontinuous hydrophobic control layer is disposed on the outer surface of the porous silica core, and the discontinuous hydrophobic control layer is formed of C8~C16 alkylsilane; Based on 100 parts by weight of the porous silica, the content of magnesium oxide and / or calcium oxide is 10-30 parts, the amount of epoxy silane coupling agent is 1-5 parts, and the amount of C8-C16 alkyl silane is 0.5-3 parts.

5. The waterproof coating according to claim 4, characterized in that: The side-chain hydroxylated long-chain chlorinated paraffin and the water-carbon dioxide dual-regulated interface-enhanced composite particles are added in the form of pre-prepared confined hydroxylated long-chain chlorinated paraffin dual-regulated composite particles. The mass ratio of the side-chain hydroxylated long-chain chlorinated paraffin to the moisture-carbon dioxide dual-regulated interface-enhanced composite particles is 1:0.4~1:1; The side-chain hydroxylated long-chain chlorinated paraffin in the confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particles is included in the amount of long-chain chlorinated paraffin in claim 1, and the moisture-carbon dioxide dual-regulation interface-enhanced composite particles are included in the amount of composite particles in claim 4.

6. A method for preparing a low-viscosity, solvent-free, single-component polyurethane waterproof coating according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Pre-dispersion: Add polyether polyol, long-chain chlorinated paraffin and dispersant to a dispersion vessel, heat to above 90°C while stirring, then add organobentonite, rutile titanium dioxide and talc, disperse at 105~120°C for 20~40 min to obtain pre-dispersion mixture; When preparing the waterproof coating according to claim 5, the confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particles are added in step S1 as a co-addition of side-chain hydroxylated long-chain chlorinated paraffin and water-carbon dioxide dual-regulation interface-enhancing composite particles. S2. Grinding and Dehydration: The pre-dispersed mixture is ground in a colloid mill and then introduced into a dehydration kettle. It is dehydrated at 117~123℃ and -95kPa~-90kPa for 1.5~2.5 hours until the moisture content of the mixture is no higher than 0.05wt%. S3. Prepolymerization reaction: Cool the dehydrated mixture to below 80℃, add toluene diisocyanate dropwise first, then add hexamethylene diisocyanate dropwise, and react at 77~83℃ for 2~3 hours until the isocyanate group content in the system reaches 1.9~2.5wt%; S4. Post-treatment: Add antioxidant, catalyst and defoamer, continue the reaction for 0.3~0.7h, then cool to below 70℃, seal and package to obtain the low viscosity solvent-free single-component polyurethane waterproof coating.

7. The preparation method according to claim 6, characterized in that, When preparing the waterproof coating according to any one of claims 3 to 5, a step of preparing side-chain hydroxylated long-chain chlorinated paraffin is further included before step S1, specifically including: 100 parts by mass of long-chain chlorinated paraffin were heated to 115-135℃, and 3-8 parts by mass of glycidyl methacrylate and 0.1-0.4 parts by mass of peroxide initiator were added under an inert atmosphere to carry out a free radical grafting reaction for 1-3 hours to obtain long-chain chlorinated paraffin containing epoxy side chains. The long-chain chlorinated paraffin containing epoxy side chains is reacted with 2-6 parts by mass of a monohydric alcohol and 0.03-0.15 parts by mass of a ring-opening catalyst at 90-110°C for 1-2 hours to cause the epoxy side chains to undergo a ring-opening reaction, forming side chains containing hydroxyl ether bonds. After the reaction is complete, vacuum devolatilization and dehydration are performed to obtain side-chain hydroxylated long-chain chlorinated paraffins with a hydroxyl value of 8~25 mgKOH / g and a moisture content of no more than 0.05 wt%.

8. The preparation method according to claim 7, characterized in that, When preparing the waterproof coating according to claim 4 or 5, a step of preparing moisture-carbon dioxide dual-regulated interface-reinforced composite particles is further included before step S1, specifically including: Porous silica is immersed in an aqueous solution of magnesium nitrate and / or calcium nitrate, and vacuum impregnated for 10 to 40 minutes under a pressure of -95 kPa to -80 kPa, so that magnesium nitrate and / or calcium nitrate enter the channels and / or openings of the porous silica. The impregnated porous silica is dried at 100~130℃ and then heat-treated at 450~650℃ for 1~3h to convert magnesium nitrate and / or calcium nitrate into magnesium oxide and / or calcium oxide. A porous silica loaded with magnesium oxide and / or calcium oxide is surface-treated with an epoxy-based silane coupling agent, which hydrolyzes the epoxy-based silane coupling agent and undergoes a condensation reaction with the silanol groups on the surface of the porous silica to form an interfacial coupling layer. Then, C8~C16 alkylsilanes are used for incomplete hydrophobic treatment to form a discontinuous hydrophobic control layer on the outer surface of the porous silica. After drying, pulverizing and sieving, moisture-carbon dioxide dual-regulated interface-enhanced composite particles with a moisture content of no more than 0.15 wt% were obtained.

9. The preparation method according to claim 8, characterized in that, When preparing the waterproof coating according to claim 5, the step of preparing confined hydroxylated long-chain chlorinated paraffin dual-regulation composite particles is included before step S1, specifically including: The side-chain hydroxylated long-chain chlorinated paraffin and the water-carbon dioxide dual-regulated interface-enhanced composite particles were mixed at a mass ratio of 1:0.4 to 1:1 and kept at 70 to 95°C and a pressure of -90 kPa to -80 kPa for 20 to 60 minutes, and then restored to normal pressure. Repeat the vacuum-atmospheric pressure cycle 2 to 4 times to allow at least part of the side-chain hydroxylated long-chain chlorinated paraffin to enter the pores and / or pore openings of the water-carbon dioxide dual-regulated interface enhanced composite particles. Subsequently, the particles were vacuum-treated at 90~110℃ and a pressure of -95kPa~-80kPa for 20~60min to obtain the confined hydroxylated long-chain chlorinated paraffin dual-regulated composite particles.

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