Environment-friendly self-repairing single-component waterborne polyurethane waterproof coating and preparation method thereof

Abstract

The application provides an environment-friendly self-repairing single-component water-based polyurethane waterproof coating and a preparation method thereof. The environment-friendly self-repairing single-component water-based polyurethane waterproof coating comprises the following components in mass fraction: 35-45% of water-based hyperbranched polyurethane resin, 10-15% of titanium white powder, 15-20% of barium sulfate, 5-10% of modified quartz powder, 0.1-1% of thickening agent, 0.2-0.3% of bactericide, 3.5-6.5% of auxiliary agent, and the balance of water. The waterproof coating contains certain fluorine atoms, has relatively stable long-acting hydrophobic performance after the paint film is dried, and can keep the paint film clean and self-cleaning for a long time. Moreover, the modified quartz powder has the effect of enhancing the mechanical properties and stability of the paint film. Meanwhile, the paint film forms a dense network structure in the drying process, so that the paint film has good flexibility and relatively high hardness. In addition, the components contain many active groups, so that the paint film can be self-repaired.

Description

Technical Field

[0001] This invention relates to the field of building exterior wall coatings, and mainly to an environmentally friendly, self-healing, single-component waterborne polyurethane waterproof coating and its preparation method. Background Technology

[0002] With the implementation of national standards for general waterproofing specifications, building waterproofing coating systems have been further standardized. For exterior wall waterproofing, the common practice is to add an internal waterproofing layer, often using waterproof mortar, JS waterproof coatings, or waterproof slurries. However, this method has drawbacks: the waterproofing layer is relatively thick, the construction process is complex, and there are compatibility issues, all of which affect construction efficiency and cost. Among commonly used exposed waterproofing coatings, oil-based polyurethane and polyurea coatings have superior performance, but they contain oil solvents and have poor environmental performance. Among water-based products, acrylic coatings have relatively poor durability and abrasion resistance, making them unable to provide long-lasting waterproofing. Furthermore, traditional water-based polyurethane coatings have relatively poor self-healing and strength properties, limiting their application. Additionally, scratches from the external environment will significantly affect their original waterproofing performance.

[0003] In existing technologies, from a waterproofing perspective, waterproof leveling mortar, JS waterproof coatings, and waterproof slurries can provide good waterproofing. However, these need to be applied inside the coating layer and have certain requirements for compatibility with subsequent coatings. They also have drawbacks such as long construction periods, high costs, and high loads on buildings. Conventional water-based polyurethane waterproof coatings mainly consist of linear polymers, which provide excellent waterproofing performance after drying and can be used as exposed coatings. However, the abrasion resistance and hardness of the coating film are slightly lower, and its long-term hydrophobicity and self-healing properties are poor. For example, patent application CN117510775A discloses a high-adhesion, environmentally friendly, low-carbon single-component waterborne polyurethane emulsion, waterproof coating, and its preparation method. The emulsion is synthesized by linear polymerization into a polymer. The coating prepared using this emulsion exhibits excellent waterproof performance and high adhesion. However, the crosslinking density of the dried film is relatively low, the film hardness is relatively low, and the self-healing function is weak, with only average hydrophobicity. Another example is patent application CN115232558B, which discloses a self-healing waterproof coating and its preparation method. This waterproof coating is prepared from modified siloxane, modified SiO2, a curing agent, a surfactant, and a solvent. The dried film exhibits strong hydrophobicity, and the self-healing waterproof coating can self-repair after damage through heating. However, it contains solvents, resulting in relatively poor environmental friendliness. Therefore, developing a self-healing, high-strength, exposed waterproof coating is of great significance.

[0004] In conclusion, it is necessary to develop a new technical solution to address the defects and shortcomings of existing technologies. Summary of the Invention

[0005] To address the aforementioned technical deficiencies, this invention provides an environmentally friendly, self-healing, single-component waterborne polyurethane waterproof coating and its preparation method. First, a hyperbranched waterborne polyurethane resin is synthesized. Then, quartz powder is modified to enhance the compatibility between components and introduce active groups. Next, functional powders, special additives, and water are compounded to prepare an environmentally friendly, self-healing, single-component waterborne polyurethane waterproof coating. Because the waterborne resin contains a certain amount of fluorine, the dried film exhibits hydrophobic properties. Simultaneously, the intertwined branched structures after drying form a dense network structure, improving the film's density and abrasion resistance. Furthermore, the interaction between the active groups in the components allows the coating to self-repair minor scratches as the external temperature rises, providing an automatic repair function. This product can be used as an exposed waterproof coating for exterior walls and roofs, forming a relatively hydrophobic, dense, self-healing, and abrasion-resistant coating, maintaining the building's long-term waterproofing effect and decorative function.

[0006] One object of the present invention is to provide an environmentally friendly, self-healing, one-component waterborne polyurethane waterproof coating, wherein the environmentally friendly, self-healing, one-component waterborne polyurethane waterproof coating comprises the following components by mass fraction:

[0007]

[0008] in,

[0009] The waterborne hyperbranched polyurethane resin is obtained by reacting isoflurone diisocyanate, tetrahydroxy compound, 2,2-dimethylolpropionic acid and octafluoropentanol.

[0010] The tetrahydroxy compound was obtained by reacting isoflurone diisocyanate and diethanolamine;

[0011] The modified quartz powder is obtained by reacting hydroxylated quartz powder with isoflurane diisocyanate and glycidol.

[0012] Furthermore, the additives are selected from one or more of dispersants, wetting agents, defoamers, thickeners, bactericides, film-forming aids, antifreeze agents, pH adjusters, or pigments and fillers.

[0013] Furthermore, the thickener is selected from one or more of hydrophobically modified cellulose and polyurethane thickeners, preferably 0.1-1%.

[0014] Furthermore, the waterborne hyperbranched polyurethane resin has excellent waterproof performance and super weather resistance, and after film formation, it has long-lasting hydrophobicity and certain self-healing properties.

[0015] Furthermore, the titanium dioxide is preferably rutile titanium dioxide, which undergoes precipitation surface treatment with silicon and aluminum and organic matter treatment, thereby improving the dispersibility and stability of rutile titanium dioxide in aqueous systems; Longbai's 996 titanium dioxide is preferred.

[0016] Furthermore, the barium sulfate is preferably ultrafine barium sulfate with excellent alkali resistance; preferably Yunhong JT202.

[0017] Further, the dispersant is a hydrophobically modified ammonium carboxylate copolymer, preferably 0.6-0.8%; the wetting agent is an alkyl polyoxyethylene ether wetting agent, preferably 0.1-0.2%; the defoamer is an organosilicon defoamer, preferably 0.4-0.6%; the bactericide is preferably 0.2-0.3%; the film-forming aid is dodecyl alcohol ester, preferably 1.0-2.0%; the antifreeze is preferably 1.0-2.0%; and the pH adjuster is preferably 0.1-0.2%.

[0018] Another object of the present invention is to provide a method for preparing the above-mentioned environmentally friendly self-healing single-component waterborne polyurethane waterproof coating, comprising the following steps:

[0019] S1. Isofolone diisocyanate, diethanolamine and acetone are mixed and reacted under low temperature conditions to obtain a tetrahydroxy compound;

[0020] S2. Isoflurone diisocyanate, the tetrahydroxy compound and butanone are mixed and heated to react; then 2,2-dimethylolpropionic acid is added and heated to react; then octafluoropentanol is added and heated to react; after the reaction is completed, the temperature is lowered, triethylamine is added to adjust the pH, water is added and stirred to mix; purified, waterborne hyperbranched polyurethane resin is obtained.

[0021] S3. Add quartz powder to NaOH solution, heat and stir to react, and obtain hydroxylated quartz powder;

[0022] S4. The hydroxylated quartz powder, isoflurone diisocyanate and glycidol are mixed, a catalyst is added, and the mixture is reacted under an inert atmosphere and heating conditions to obtain modified quartz powder.

[0023] S5. Add a portion of the thickener to water and stir to disperse at 500-750 rpm; add film-forming aid, wetting agent, defoamer, dispersant, antifreeze agent, and pH adjuster, and stir to disperse at 500-800 rpm; then add pigments, fillers, titanium dioxide, barium sulfate, and the modified quartz powder, and stir to disperse at 1300-1500 rpm; then add the waterborne hyperbranched polyurethane resin and bactericide, and stir to disperse at 500-700 rpm; then add the remaining thickener, and stir to disperse at 500-700 rpm. After the viscosity test is qualified, an environmentally friendly self-healing single-component waterborne polyurethane waterproof coating is obtained.

[0024] Furthermore, the viscosity ranges from 100 to 130 KU.

[0025] Further, in step S1, the mass ratio of isoflurane diisocyanate, diethanolamine and acetone is 1:(0.5-1.5):(1.5-2.5).

[0026] Furthermore, in step S1, the low temperature is 0-10℃.

[0027] Further, in step S2, the mass ratio of isoflurane diisocyanate, tetrahydroxy compound, butanone, 2,2-dimethylolpropionic acid and octafluoropentanol is 1:(0.5-1.5):(3-5):(0.1-1):(0.1-1).

[0028] Furthermore, in step S2, the heating temperature is 70-90℃.

[0029] Furthermore, in step S2, the pH range is 7-8.

[0030] Furthermore, in step S3, the heating temperature is 80-100℃.

[0031] Further, in step S4, the mass ratio of the hydroxylated quartz powder, isoflurone diisocyanate, and glycidol is 100:(1-10):(1-10).

[0032] Furthermore, in step S4, the heating temperature is 40-60°C.

[0033] The present invention has the following beneficial effects:

[0034] This invention first synthesizes a waterborne hyperbranched polyurethane resin, then modifies quartz powder to enhance the compatibility between components and introduce active groups. Using this resin as the main film-forming material, a novel waterproof coating is prepared in combination with modified quartz powder, functional powders, and additives. This waterproof coating, containing a certain amount of fluorine atoms, exhibits relatively stable and long-lasting hydrophobic properties after the paint film dries, enabling it to maintain a clean and self-cleaning state for an extended period. Furthermore, the modified quartz powder incorporates structures similar to those of the waterborne hyperbranched polyurethane resin and polyurethane thickeners, resulting in good compatibility between components, improved dispersion, and enhanced mechanical properties and stability of the paint film. Simultaneously, during the drying process, the branched structures intertwine to form a dense network structure, improving the film's density and abrasion resistance, giving it good flexibility and relatively high hardness. In addition, the waterborne hyperbranched polyurethane resin and modified quartz powder contain numerous active groups such as hydroxyl, carboxyl, and epoxy groups, enabling the paint film to self-repair after minor external scratches are exposed to increased external temperature, thus providing an automatic repair function. This coating can be used as a waterproof coating for exposed exterior walls, greatly improving the longevity of the building's decoration. Detailed Implementation

[0035] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0036] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0037] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0038] The following raw materials are used in the embodiments and comparative examples of this invention:

[0039] The titanium dioxide is rutile titanium dioxide, grade 996, purchased from Longbai.

[0040] The barium sulfate was 3000 mesh high-gloss barium sulfate, grade JT202, purchased from Yunhong.

[0041] The quartz powder has a mesh size of 325 and was purchased from Heyuan Hongfa.

[0042] The dispersant brand is D-26, purchased from Puwei.

[0043] The wetting agent, brand name LCN070, was purchased from Klein.

[0044] The defoamer brand name is ST 2410AC, purchased from BASF.

[0045] The thickeners include hydrophobically modified cellulose thickeners and polyurethane thickeners in a mass ratio of 2:1; the hydrophobically modified cellulose thickener is brand name HER 30M, purchased from Grace; the polyurethane thickener is RM-8W, purchased from Dow Chemical.

[0046] The fungicide was MBS 5050, purchased from Guangzhou Duwei Trading Co., Ltd.

[0047] The film-forming aid is dodecyl alcohol ester.

[0048] The antifreeze is ethylene glycol.

[0049] The pH adjuster is AMP-95.

[0050] Polyethylene glycol 400, purchased from Dow Chemical.

[0051] Example 1

[0052] An environmentally friendly, self-healing, one-component waterborne polyurethane waterproof coating, comprising the following components by mass fraction:

[0053]

[0054] The preparation method of the above-mentioned environmentally friendly self-healing single-component waterborne polyurethane waterproof coating includes the following steps:

[0055] S1. 25.7 parts of isoflurane diisocyanate, 24.3 parts of diethanolamine and 50 parts of anhydrous acetone were mixed and reacted at 0°C for 4 h. After titration with NCO value to 0, the mixture was gradually placed to room temperature to obtain a tetrahydroxy compound.

[0056] S2. 33 parts of isoflurane diisocyanate, 32 parts of the aforementioned tetrahydroxy compound, and 100 parts of butanone were mixed and reacted at 80°C for 4 hours; then 16 parts of 2,2-dimethylolpropionic acid were added and reacted at 80°C for 3 hours; then 17 parts of octafluoropentanol were added and reacted at 80°C for 5 hours; after the reaction was completed, the mixture was cooled to room temperature, triethylamine was added to adjust the pH to 7.5, deionized water was added, and the mixture was stirred until homogeneous; finally, butanone and acetone were removed by vacuum distillation to obtain waterborne hyperbranched polyurethane resin.

[0057] S3. Immerse quartz powder in NaOH solution (1 mol / L), stir and react at 90℃ for 3 h, filter, wash and dry to obtain hydroxylated quartz powder;

[0058] S4. Using acetone as a solvent, the hydroxylated quartz powder, isoflurone diisocyanate, and glycidol (hydroxylated quartz powder: isoflurone diisocyanate: glycidol = 10:1:1, m / m / m) are mixed, and dibutyltin dilaurate (1% by mass of reactants) is added. The mixture is reacted for 5 hours under a nitrogen atmosphere and at 45°C. After filtration, washing, and drying, modified quartz powder is obtained.

[0059] S5. According to the above mass fraction, add the hydrophobic modified cellulose thickener to water and stir and disperse at 500 rpm for 5 min; add film-forming aid, wetting agent, defoamer, dispersant, antifreeze agent and pH adjuster, and stir and disperse at 700 rpm for 10 min; then add titanium dioxide, barium sulfate and the modified quartz powder, and stir and disperse at 1500 rpm for 20 min until the fineness is less than 60 μm; then add the waterborne hyperbranched polyurethane resin and bactericide, and stir and disperse at 800 rpm for 10 min; then add polyurethane thickener, and stir and disperse at 800 rpm for 20 min. The viscosity at 25℃ is 105.5 KU, thus obtaining an environmentally friendly self-healing single-component waterborne polyurethane waterproof coating.

[0060] Example 2

[0061] An environmentally friendly, self-healing, one-component waterborne polyurethane waterproof coating, comprising the following components by mass fraction:

[0062]

[0063] The preparation method of the above-mentioned environmentally friendly self-healing single-component waterborne polyurethane waterproof coating is the same as that in Example 1, and its viscosity is 121.3 KU when tested at 25°C.

[0064] Comparative Example 1

[0065] An environmentally friendly, self-healing, single-component waterborne polyurethane waterproof coating is disclosed. The difference between this comparative example and Example 1 is that in step S5, the waterborne hyperbranched polyurethane resin is replaced by an equal mass of benzoic acid emulsion BADEFU 9045A. The remaining components and preparation method are the same as in Example 1.

[0066] Comparative Example 2

[0067] An environmentally friendly, self-healing, single-component waterborne polyurethane waterproof coating is disclosed. The difference between this comparative example and Example 1 is that in step S5, the waterborne hyperbranched polyurethane resin is replaced by an equal mass of waterborne polyurethane dispersion Wanhua 8355. The remaining components and preparation method are the same as in Example 1.

[0068] Comparative Example 3

[0069] An environmentally friendly, self-healing, single-component waterborne polyurethane waterproof coating is disclosed. The difference between this comparative example and Example 1 is that step S1 is omitted. In step S2, the tetrahydroxy compound is replaced by polyethylene glycol 400 in equal mass. The remaining components and preparation method are the same as in Example 1.

[0070] Comparative Example 4

[0071] An environmentally friendly, self-healing, single-component waterborne polyurethane waterproof coating is disclosed. The difference between this comparative example and Example 1 is that the modified quartz powder is replaced with commercially available quartz powder, while the other components and preparation methods are the same as in Example 1.

[0072] Test case

[0073] Key performance parameters of Examples 1-2 and Comparative Examples 1-4 were tested.

[0074] Test method:

[0075] Viscosity: 25℃, measured by Stormer viscometer.

[0076] Thermal storage stability: Stored at 55℃ for 30 days.

[0077] Contrast ratio, surface drying time, washability, water resistance, alkali resistance, and temperature change resistance: refer to GB / T 9755-2014.

[0078] Impermeability, standard tensile strength, standard elongation, low-temperature bending, acid-treated elongation, tear strength, and resistance to artificial weathering: refer to JC / T 864-2023.

[0079] Film hardness: Refer to GB / T 6739-2022.

[0080] Paint film condition after scratch: The paint film condition after being placed at 80℃ for 24 hours following a minor scratch by a knife.

[0081] The test results are shown in Table 1.

[0082] Table 1 Performance test results of Examples 1-2 and Comparative Examples 1-4

[0083]

[0084]

[0085]

[0086] The test results above show that the environmentally friendly self-healing single-component waterborne polyurethane waterproof coatings prepared in Examples 1-2 have basically no abnormalities in workability, a contrast ratio greater than 0.9, a scrub resistance greater than 10,000 times, no abnormalities in low-temperature storage, relatively good hydrophobicity, water impermeability and strength performance, and a certain degree of self-healing performance. After being stored at 55℃ for 6 months, the raindrops on the coating film rolled off in a round shape, indicating good hydrophobicity. In Comparative Examples 1-2, the self-made waterborne polyurethane resin was replaced alone, resulting in relatively poor hydrophobicity and self-healing properties of the paint film. This fully demonstrates that to achieve the effect of environmentally friendly self-healing single-component waterborne polyurethane waterproof coating, some optimization is needed in the selection of resin emulsion. In Comparative Example 3, tetrahydroxy compounds were not added during the preparation of waterborne hyperbranched polyurethane resin; commercially available polyethylene glycol 400 was used instead, resulting in the synthesis of a difunctional linear waterborne polyurethane resin. When used in the coating formulation, the molecules of the paint film were less intertwined after drying, leading to a decrease in film density and abrasion resistance. Furthermore, the limited interaction between active groups in the components prevented the film from self-healing after minor external scratches as the external temperature increased. In Comparative Example 4, modified quartz powder was replaced with commercially available quartz powder, resulting in poor compatibility between components, which affected the mechanical properties and stability of the paint film. Additionally, due to the lack of introduced active groups, the self-healing effect of the paint film was poor.

[0087] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0088] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An environmentally friendly self-repairing single-component waterborne polyurethane waterproof coating, characterized in that, The environment-friendly self-repairing single-component water-based polyurethane waterproof coating comprises the following components by mass fraction: Among them, The water-based hyperbranched polyurethane resin is obtained by reacting isophorone diisocyanate, a tetrahydroxy compound, 2,2-dimethylol propionic acid and octafluoro-pentanol; The tetrahydroxy compound is obtained by reacting isophorone diisocyanate and diethanolamine; The modified quartz powder is obtained by reacting the hydroxylated quartz powder, isophorone diisocyanate and epoxy propyl alcohol. 2.The environment-friendly self-repairing single-component waterborne polyurethane waterproof coating according to claim 1, characterized in that, The auxiliary agent is selected from one or more of a dispersing agent, a wetting agent, a defoaming agent, a thickening agent, a bactericide, a film-forming auxiliary agent, an antifreezing agent, a pH regulator or a pigment and filler. 3.The environment-friendly self-repairing single-component waterborne polyurethane waterproof coating according to claim 2, characterized in that, The thickening agent is selected from one or more of a hydrophobically modified cellulose and a polyurethane thickening agent.

4. The preparation method of the environment-friendly self-repairing single-component waterborne polyurethane waterproof coating according to any one of claims 1-3, characterized in that, The method comprises the following steps: S1, blending isophorone diisocyanate, diethanolamine and acetone, and reacting under low temperature conditions to obtain a tetrahydroxy compound; S2, blending isophorone diisocyanate, the tetrahydroxy compound and butanone, and heating to react; then adding 2,2-dimethylol propionic acid and heating to react; further adding octafluoro-pentanol and heating to react; after the reaction is completed, cooling, adding triethylamine to adjust the pH, adding water and stirring to mix; purification to obtain a water-based hyperbranched polyurethane resin; S3, adding quartz powder into a NaOH solution, heating and stirring to react, and obtaining a hydroxylated quartz powder; S4, blending the hydroxylated quartz powder, isophorone diisocyanate and epoxy propyl alcohol, adding a catalyst, and reacting under inert atmosphere and heating conditions to obtain a modified quartz powder; S5, adding part of the thickening agent into water and stirring to disperse; adding a film-forming auxiliary agent, a wetting agent, a defoaming agent, a dispersing agent, an antifreezing agent and a pH regulator and stirring to disperse; further adding a pigment and filler, titanium white, barium sulfate and the modified quartz powder and stirring to disperse; then adding the water-based hyperbranched polyurethane resin and a bactericide and stirring to disperse; further adding the remaining thickening agent, stirring to disperse, and obtaining the environment-friendly self-repairing single-component water-based polyurethane waterproof coating after testing the viscosity. 5.The preparation method of the environment-friendly self-repairing single-component waterborne polyurethane waterproof coating of claim 4, characterized in that, In step S1, the mass ratio of the isophorone diisocyanate, diethanolamine and acetone is 1:(0.5-1.5):(1.5-2.5). 6.The preparation method of the environment-friendly self-repairing single-component waterborne polyurethane waterproof coating of claim 4, characterized in that, In step S1, the low temperature is 0-10℃. 7.The preparation method of the environment-friendly self-repairing single-component waterborne polyurethane waterproof coating of claim 4, characterized in that, In step S2, the mass ratio of the isophorone diisocyanate, tetrahydroxy compound, butanone, 2,2-dimethylol propionic acid and octafluoro-pentanol is 1:(0.5-1.5):(3-5):(0.1-1):(0.1-1). 8.The preparation method of the environment-friendly self-repairing single-component waterborne polyurethane waterproof coating of claim 4, characterized in that, In step S2, the heating temperature is 70-90℃. 9.The preparation method of the environment-friendly self-repairing single-component waterborne polyurethane waterproof coating of claim 4, characterized in that, In step S3, the heating temperature is 80-100℃. 10.The preparation method of the environment-friendly self-repairing single-component waterborne polyurethane waterproof coating of claim 4, characterized in that, In step S4, the mass ratio of the hydroxylated quartz powder, isophorone diisocyanate and epoxy propyl alcohol is 100:(1-10):(1-10).

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