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

Abstract

The invention provides an environment-friendly self-repairing single-component waterborne polyurethane waterproof coating and a preparation method thereof. The environment-friendly self-repairing single-component waterborne polyurethane waterproof coating is prepared from the following components in percentage by mass: 35 to 45 percent of waterborne hyperbranched polyurethane resin, 10 to 15 percent of titanium dioxide, 15 to 20 percent of barium sulfate, 5 to 10 percent of modified quartz powder, 0.1 to 1 percent of a thickening agent, 0.2 to 0.3 percent of a sterilizing agent, 3.5 to 6.5 percent of an auxiliary agent and the balance of water. The waterproof coating contains certain fluorine atoms, so that a paint film has relatively stable long-acting hydrophobic performance after being dried, and the paint film can be kept clean and self-cleaning for a long time; in addition, the modified quartz powder has the effect of enhancing the mechanical property and stability of the paint film; and meanwhile, the paint film forms a compact network structure in the drying process, so that the paint film has relatively good flexibility and relatively high hardness. In addition, the components contain more active groups, so that the paint film can be self-repaired.

Description

Technical Field

[0001] The present invention relates to the field of building exterior wall coatings, and mainly relates to an environmentally friendly self-healing one-component waterborne polyurethane waterproof coating and a preparation method thereof. Background Art

[0002] With the implementation of the national standard for general waterproofing specifications, the building waterproof coating system has been further standardized. In the waterproof treatment of building exterior walls, the common practice is to add a waterproof layer process inside, such as waterproof mortar, JS waterproof coating, waterproof slurry, etc. However, the disadvantages of this method are that the construction thickness of the waterproof layer is relatively high, the construction process is more, and there are problems with construction compatibility, which all affect the construction efficiency and cost. Among the commonly used exposed waterproof coatings, oil-based polyurethane and polyurea coatings have relatively excellent performance, but they contain oil-based solvents and have poor environmental protection performance; among water-based products, acrylic coatings have relatively poor durability and wear resistance and cannot provide long-term waterproofing. In addition, traditional waterborne polyurethane coatings have relatively poor self-healing and strength properties, which limit their scope of use. At the same time, if scratched by the external environment, the original waterproof performance will be greatly affected.

[0003] In the prior art, from the perspective of waterproofing, currently using waterproof leveling mortar, JS waterproof coating, and waterproof slurry can play a good waterproofing role, but they need to be applied inside the coating, and there are certain requirements for subsequent coating compatibility. There are defects such as a long construction period, high cost, and a relatively high load on the building. The main film-forming substance of conventional waterborne polyurethane waterproof coatings is a linear polymer. After drying and film-forming, the waterproof performance is relatively excellent, and it can be used as an exposed type. However, the wear resistance and hardness of the paint film are slightly lower, and the long-term hydrophobicity and self-healing performance are poor. For example, the invention patent with the application number CN117510775A discloses a one-component waterborne polyurethane emulsion, waterproof coating with high bonding strength and environmental protection and low carbon, and a preparation method thereof. The emulsion synthesis is a linear polymerization to form a polymer. Using this emulsion to prepare a coating, the waterproof performance is excellent and the bonding strength is relatively high. However, the dry crosslinking density of the paint film is relatively low, the hardness of the paint film is relatively low, and the self-healing function is weak. The hydrophobicity of the paint film itself is relatively ordinary; for example, the invention patent with the application number CN115232558B discloses a self-healing waterproof coating and a preparation method thereof. This waterproof coating is prepared from modified silicone, modified SiO2, curing agent, surfactant, and solvent. After the paint film dries, the hydrophobicity is strong, and the self-healing waterproof coating can achieve self-healing after being damaged by heating. However, it contains solvents and has relatively poor environmental protection. Therefore, it is of great significance to develop an exposed waterproof coating that can self-heal and has high strength.

[0004] In summary, it is necessary to develop a new technical solution to solve the defects and deficiencies existing in the prior art. Summary of the Invention

[0005] In view of the above-mentioned technical defects, the present invention provides an environmentally friendly self-healing one-component waterborne polyurethane waterproof coating and a preparation method thereof. First, the present invention synthesizes a waterborne polyurethane resin with a hyperbranched structure, then modifies quartz powder to enhance the compatibility between components and introduce active groups, and then compound functional powder materials, special additives and water to prepare an environmentally friendly self-healing one-component waterborne polyurethane waterproof coating. Since the waterborne resin contains a certain fluorine content, the paint film has certain hydrophobic properties after drying. At the same time, after the paint film dries, the branched structures are intertwined to form a dense network structure, which improves the density and wear resistance of the paint film. And the interaction between the active groups in the components enables it to self-repair after being slightly scratched externally as the external temperature rises, playing an automatic repair function; this product can be used for exposed waterproof coatings such as exterior walls and roofs to form a relatively hydrophobic, dense, self-healing and wear-resistant coating, maintaining the long-term waterproof effect and decorative function of the building.

[0006] An object of the present invention is to provide an environmentally friendly self-healing one-component waterborne polyurethane waterproof coating, and the environmentally friendly self-healing one-component waterborne polyurethane waterproof coating comprises components with the following mass fractions:

[0007]

[0008] Among them,

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

[0010] The tetrahydroxy compound is obtained by reacting isophorone diisocyanate and diethanolamine;

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

[0012] Further, the additives are selected from one or more of a dispersant, a wetting agent, an antifoaming agent, a thickener, a bactericide, a film-forming aid, an antifreeze, a pH regulator or a pigment filler.

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

[0014] Further, the waterborne hyperbranched polyurethane resin has excellent waterproof performance and super weather resistance, and at the same time has long-term hydrophobicity and certain self-healing performance after film formation.

[0015] Further, the titanium dioxide is preferably rutile titanium dioxide, which is subjected to precipitation surface treatment and organic treatment with silicon and aluminum, improving the dispersibility and stability of rutile titanium dioxide in the aqueous system; preferably, 996 titanium dioxide of Longbai is used.

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

[0017] Further, the dispersant is a dispersant of the hydrophobic modified ammonium carboxylate copolymer type, preferably 0.6 - 0.8%; the wetting agent is an alkyl polyoxyethylene ether type wetting agent, preferably 0.1 - 0.2%; the defoaming agent is an organosilicon type defoaming agent, preferably 0.4 - 0.6%; the bactericide is preferably 0.2 - 0.3%; the film-forming aid is lauryl alcohol ester, preferably 1.0 - 2.0%; the antifreeze is preferably 1.0 - 2.0%; the pH regulator is preferably 0.1 - 0.2%.

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

[0019] S1. Blend isophorone diisocyanate, diethanolamine and acetone, and react under low-temperature conditions to obtain a tetrahydroxy compound;

[0020] S2. Blend isophorone diisocyanate, the tetrahydroxy compound and methyl ethyl ketone, and heat to react; then add 2,2-dimethylolpropionic acid and heat to react; then add octafluoropentanol and heat to react; after the reaction is completed, cool down, add triethylamine to adjust the pH, add water, and stir and mix; purify to obtain a waterborne hyperbranched polyurethane resin;

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

[0022] S4. Blend the hydroxylated quartz powder, isophorone diisocyanate and glycidol, add a catalyst, and react under an inert atmosphere and heating conditions to obtain modified quartz powder;

[0023] S5. Add part of the thickener to water and stir and disperse at 500 - 750 rpm; add the film-forming aid, wetting agent, defoaming agent, dispersant, antifreeze and pH regulator, and stir and disperse at 500 - 800 rpm; then add the pigment filler, titanium dioxide, barium sulfate and the modified quartz powder, and stir and disperse at 1300 - 1500 rpm; then add the waterborne hyperbranched polyurethane resin and the bactericide, and stir and disperse at 500 - 700 rpm; then add the remaining thickener and stir and disperse at 500 - 700 rpm. After testing that the viscosity is qualified, obtain the environmentally friendly self-healing one-component waterborne polyurethane waterproof coating.

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

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

[0026] Further, in step S1, the low temperature is 0 - 10 °C.

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

[0028] Further, in step S2, the heating temperature is 70 - 90 °C.

[0029] Further, in step S2, the pH ranges from 7 to 8.

[0030] Further, in step S3, the heating temperature is 80 - 100 °C.

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

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

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

[0034] The present invention first synthesizes an aqueous hyperbranched polyurethane resin, then modifies quartz powder to enhance the compatibility between components and introduce active groups. Then, using this resin as the main film-forming substance, a new waterproof coating is prepared by combining modified quartz powder, functional powder materials, and additives. Due to the presence of a certain amount of fluorine atoms inside the waterproof coating, it has relatively stable long-term hydrophobic performance after the paint film dries, and can keep the paint film clean and self-cleaning for a long time. Moreover, the modified quartz powder introduces a structure similar to that of components such as aqueous hyperbranched polyurethane resin and polyurethane thickeners, with good compatibility between components, improving the dispersion effect, enhancing the mechanical properties and stability of the paint film. At the same time, during the drying process of the paint film, the branched structures are intertwined to form a dense network structure, improving the density and wear resistance of the paint film, making the paint film have good flexibility and relatively high hardness. In addition, components such as aqueous hyperbranched polyurethane resin and modified quartz powder contain many active groups such as hydroxyl groups, carboxyl groups, and epoxy groups, enabling the paint film to self-repair after being slightly scratched externally and the external temperature rises, playing an automatic repair function. This coating can be used as an exterior exposed waterproof coating, greatly improving the long-term decorative performance of buildings. Detailed Embodiments

[0035] To more clearly illustrate the technical solutions of the present invention, the following examples are listed. The raw materials, reactions, and post-treatment means appearing in the examples are all common raw materials on the market and technical means well-known to those skilled in the art, unless otherwise specifically stated.

[0036] The terms "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects under certain circumstances. However, in the same or other circumstances, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0037] It should be understood that, except in any operating examples or otherwise indicated, all numbers representing the amounts of ingredients used in the specification and claims, for example, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and appended claims are approximate values that vary depending on the desired properties to be obtained by the present invention.

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

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

[0040] The barium sulfate is 3000-mesh high-gloss barium sulfate, with the grade of JT202, purchased from Yunhong.

[0041] The mesh number of the quartz powder is 325 mesh, and it is purchased from Heyuan Hongfa.

[0042] The dispersant grade is D-26, and it is purchased from Puwei.

[0043] The wetting agent grade is LCN070, and it is purchased from Kline.

[0044] The defoaming agent grade is ST 2410AC, and it is purchased from BASF.

[0045] The thickener includes a hydrophobically modified cellulose thickener and a polyurethane thickener, and their mass ratio is 2:1; among them, the hydrophobically modified cellulose thickener grade is HER 30M, and it is purchased from Grace; the polyurethane thickener is RM-8W, and it is purchased from Dow Chemical.

[0046] The bactericide is MBS 5050, and it is purchased from Guangzhou Duwei Trading.

[0047] The film-forming aid is lauryl alcohol acetate.

[0048] The antifreeze is ethylene glycol.

[0049] The pH regulator 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, and the environmentally friendly self-healing one-component waterborne polyurethane waterproof coating includes the following components by mass fraction:

[0053]

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

[0055] S1. Blend 25.7 parts of isophorone diisocyanate, 24.3 parts of diethanolamine and 50 parts of anhydrous acetone, react at 0 °C for 4 h, titrate until the NCO value is 0, and then gradually let it stand to room temperature to obtain a tetrahydroxy compound;

[0056] S2. Blend 33 parts of isophorone diisocyanate, 32 parts of the tetrahydroxy compound and 100 parts of methyl ethyl ketone, react at 80 °C for 4 h; then add 16 parts of 2,2-dimethylolpropionic acid, react at 80 °C for 3 h; then add 17 parts of octafluoropentanol, react at 80 °C for 5 h; after the reaction is completed, cool down to room temperature, add triethylamine to adjust the pH to 7.5, add deionized water, and stir and mix evenly; finally, remove methyl ethyl ketone and acetone by vacuum distillation to obtain a waterborne hyperbranched polyurethane resin;

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

[0058] S4. Using acetone as the solvent, blend the hydroxylated quartz powder, isophorone diisocyanate, and glycidol (hydroxylated quartz powder: isophorone diisocyanate: glycidol = 10:1:1, m / m / m), add dibutyltin dilaurate (1% of the reactant mass), react under a nitrogen atmosphere at 45 °C for 5 h, filter, wash, and dry to obtain modified quartz powder;

[0059] S5. According to the above mass fractions, add the hydrophobic modified cellulose thickener to water and stir and disperse at a speed of 500 rpm for 5 min; add a film-forming aid, wetting agent, defoaming agent, dispersant, antifreeze, and pH regulator, and stir and disperse at a speed of 700 rpm for 10 min; then add titanium dioxide, barium sulfate, and the modified quartz powder, and stir and disperse at a speed of 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 a speed of 800 rpm for 10 min; then add a polyurethane thickener and stir and disperse at a speed of 800 rpm for 20 min. The viscosity measured at 25 °C is 105.5 KU to obtain an environmentally friendly self-healing one-component waterborne polyurethane waterproof coating.

[0060] Example 2

[0061] An environmentally friendly self-healing one-component waterborne polyurethane waterproof coating, the environmentally friendly self-healing one-component waterborne polyurethane waterproof coating includes components with the following mass fractions:

[0062]

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

[0064] Comparative Example 1

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

[0066] Comparative Example 2

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

[0068] Comparative Example 3

[0069] An environmentally friendly self-healing one-component waterborne polyurethane waterproof coating. The difference between this comparative example and Example 1 is that step S1 is not carried out, and in step S2, the tetrahydroxy compound is replaced with polyethylene glycol 400 in equal mass, and the remaining components and preparation methods are the same as those in Example 1.

[0070] Comparative Example 4

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

[0072] Test Example

[0073] The key properties of Examples 1-2 and Comparative Examples 1-4 were tested.

[0074] Test method:

[0075] Viscosity: Test value measured by Stormer viscometer at 25°C.

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

[0077] Contrast ratio, surface dry time, scrub resistance, water resistance, alkali resistance, temperature change resistance: Refer to GB / T 9755-2014.

[0078] Water impermeability, tensile strength at standard state, elongation at standard state, low temperature bending, elongation after acid treatment, tear strength, resistance to artificial weathering: Refer to JC / T 864-2023.

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

[0080] Film state after scratching: Slightly scratched with a knife, and the film state after being placed at 80°C for 24h.

[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] From the above test results, it can be seen that the workability of the environmentally friendly self-healing one-component waterborne polyurethane waterproof coating prepared in Examples 1-2 is basically normal, the contrast ratio is greater than 0.9, the scrub resistance is greater than 10,000 times, the low-temperature storage is normal, the hydrophobicity, water impermeability and strength performance are relatively good, and it has a certain self-healing performance. After 6 months of heat storage at 55 °C, when the paint film is constructed, the raindrops roll down in a circular shape, indicating good hydrophobicity. In Comparative Examples 1-2, when the self-made waterborne polyurethane resin was replaced alone, the hydrophobicity and self-healing performance of the paint film were relatively poor. This fully shows that to achieve the effect of the environmentally friendly self-healing one-component waterborne polyurethane waterproof coating, some optimizations are needed in the selection of resin emulsions; in Comparative Example 3, tetrahydroxy compounds were not added during the preparation of the waterborne hyperbranched polyurethane resin, and polyethylene glycol 400 commercially available was used instead to synthesize a difunctional linear waterborne polyurethane resin. When used in the coating formulation, the molecules are relatively less entangled with each other after the paint film dries, the compactness and wear resistance of the paint film decrease, and the interaction between the active groups in the components is less, so that it cannot self-repair after being scratched slightly externally with the increase of the external temperature; in Comparative Example 4, the modified quartz powder was replaced with commercially available quartz powder in equal mass, and the compatibility between the components was poor, which in turn affected the mechanical properties and stability of the paint film. At the same time, due to the lack of introduction of active groups, the self-healing effect of the paint film was poor.

[0087] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0088] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard 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 one-component waterborne polyurethane waterproof coating, characterized in that: The environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating comprises the following components by mass fraction: in, The waterborne hyperbranched polyurethane resin is obtained by reacting isophorone diisocyanate, a tetrahydroxy compound, 2,2-dimethylol propionic acid and octafluoropentanol; The tetrahydroxy compound is obtained by reacting isophorone diisocyanate and diethanolamine; The modified quartz powder is obtained by reacting hydroxylated quartz powder with isophorone diisocyanate and glycidol.

2. The environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 1, characterized in that: The auxiliary agent is selected from one or more of a dispersant, a wetting agent, a defoamer, a thickener, a bactericide, a film-forming aid, an antifreeze agent, a pH regulator or a pigment or filler.

3. The environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 2, characterized in that: The thickener is selected from one or more of hydrophobically modified cellulose and polyurethane thickeners.

4. The method for preparing the environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to any one of claims 1 to 3, characterized in that: The steps include: S1, mixing isophorone diisocyanate, diethanolamine and acetone, and reacting them under low temperature to obtain a tetrahydroxy compound; S2, mixing isophorone diisocyanate, the tetrahydroxy compound and butanone, heating to react; then adding 2,2-dimethylolpropionic acid, heating to react; then adding octafluoropentanol, heating to react; after the reaction is completed, cooling, adding triethylamine to adjust the pH, adding water, and stirring to mix; Purification to obtain water-based hyperbranched polyurethane resin; S3, adding quartz powder into NaOH solution, heating and stirring to react, to obtain hydroxylated quartz powder; S4, blending the hydroxylated quartz powder, isophorone diisocyanate and glycidol, adding a catalyst, and reacting them under an inert atmosphere and heating conditions to obtain modified quartz powder; S5. Add part of the thickener into water and stir to disperse; add film-forming aid, wetting agent, defoamer, dispersant, antifreeze and pH adjuster, stir to disperse; then add pigments, titanium dioxide, barium sulfate and the modified quartz powder, stir to disperse; then add the water-based hyperbranched polyurethane resin and bactericide, stir to disperse; then add the remaining thickener, stir to disperse, and after the viscosity is tested and qualified, obtain an environmentally friendly self-healing one-component water-based polyurethane waterproof coating.

5. The method for preparing the environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 4, characterized in that: In step S1, the mass ratio of isophorone diisocyanate, diethanolamine and acetone is 1:(0.5-1.5):(1.5-2.5).

6. The method for preparing the environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 4, characterized in that: In step S1, the low temperature is 0-10°C.

7. The method for preparing the environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 4, characterized in that: In step S2, the mass ratio of isophorone diisocyanate, tetrahydroxy compound, butanone, 2,2-dihydroxymethylpropionic acid and octafluoropentanol is 1:(0.5-1.5):(3-5):(0.1-1):(0.1-1).

8. The method for preparing the environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 4, characterized in that: In step S2, the heating temperature is 70-90°C.

9. The method for preparing the environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 4, characterized in that: In step S3, the heating temperature is 80-100°C.

10. The method for preparing the environmentally friendly self-repairing one-component waterborne polyurethane waterproof coating according to claim 4, characterized in that: In step S4, the mass ratio of the hydroxylated quartz powder, isophorone diisocyanate and glycidol is 100:(1-10):(1-10).

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