Impact-resistant water-based bio-based exterior wall coating and preparation method thereof

Abstract

The invention discloses an impact-resistant water-based bio-based exterior wall coating and a preparation method thereof. The coating comprises the following components in percentage by mass: 12-24% of water, 50-65% of water-based bio-based polyurethane resin, 8-18% of a modified porous material, 5-10% of filler and 3-8% of an auxiliary agent, the preparation method of the modified porous material comprises the following steps: dispersing gamma-aminopropyltriethoxysilane or 3-glycidoxypropyltrimethoxysilane in a dopamine hydrochloride solution, adjusting the pH value to 8-9, then adding diatomite or zeolite, and carrying out soaking treatment in a stirring state; after the reaction is finished, filtering, washing, freeze-drying and crushing to obtain the modified porous material. A coating formed by the coating has excellent impact resistance and excellent adhesive force, and the safety of a building and the durability of the coating can be improved.

Description

Technical Field

[0001] The invention relates to an impact-resistant water-based bio-based exterior wall paint and a preparation method thereof, belonging to the technical field of paint preparation. Background Art

[0002] With the rapid development of the construction industry, exterior wall coatings, as an important part of building materials, bear the important function of protecting buildings and improving the appearance of buildings. Traditional exterior wall coatings are mainly based on polymer synthetic resins and usually contain a variety of organic solvents and additives. These ingredients may pollute the environment and have a negative impact on human health during use and production. Therefore, the development of environmentally friendly water-based coatings has become one of the current research hotspots. Water-based bio-based coatings are increasingly favored due to their low volatile organic compound (VOCs) emissions and excellent ecological safety. Bio-based materials are usually derived from renewable plants, are sustainable, and meet the needs of modern green buildings. However, despite the advantages of water-based bio-based coatings in environmental performance, their mechanical properties such as impact resistance and durability still need to be improved. In addition, impact resistance is an important performance indicator of exterior wall coatings, especially when affected by the external environment, the coating needs to be able to withstand external impact to maintain its integrity and beauty.

[0003] Existing bio-based exterior wall coatings perform poorly in terms of impact resistance. Since the molecular structure and chemical composition of bio-based materials are different from those of petroleum-based materials, they have natural disadvantages in physical and mechanical properties. This causes bio-based coatings to be more prone to cracking, peeling or damage when subjected to external impacts, such as collisions and scratches, affecting the protective effect and service life of the coating. Bio-based coatings are generally inferior to traditional coatings in terms of mechanical properties, such as tensile strength, hardness and toughness. These performance deficiencies limit the application of bio-based coatings under high loads and harsh environments. In the prior art, a bio-based nano-additive has been studied and developed, which significantly improves the impact resistance, corrosion resistance and flame retardancy of polyurea (PUA) coatings by co-assembling montmorillonite (MMT) with chitosan, phytic acid and urea to form a nano-hybrid (CPN@MMT). Studies have shown that the addition of CPN@MMT not only improves the mechanical and impact protection properties of PUA coatings, but also reduces heat release and smoke by forming a dense carbon layer, thereby enhancing fire safety (Han S, Li S, Zhang X, et al. Enhancing the protective performance of anti-impact, corrosion resistant and flame retardant polyurea coatings using bio-based supramolecular decorated montmorillonite[J]. Construction and Building Materials, 2024, 435: 136721.), but the preparation process of this composite is complicated, resulting in a long production process and high production costs.

[0004] Therefore, developing a new type of water-based bio-based exterior wall coating that is both environmentally friendly and has excellent impact resistance has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to provide an impact-resistant water-based bio-based exterior wall paint and a preparation method thereof. The coating formed by the paint has excellent impact resistance and excellent adhesion, and can improve the safety of buildings and the durability of the coating.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An impact-resistant water-based bio-based exterior wall paint comprises the following components by mass percentage: 12-24% water, 50-65% water-based bio-based polyurethane resin, 8-18% modified porous material, 5-10% filler and 3-8% additive;

[0008] Wherein, the preparation method of the modified porous material is:

[0009] Disperse γ-aminopropyltriethoxysilane or 3-glycidyloxypropyltrimethoxysilane in a dopamine hydrochloride solution, adjust the pH to 8-9, add diatomaceous earth or zeolite, and soak under stirring; after the end, filter, wash, freeze-dry and crush to obtain a modified porous material.

[0010] Preferably, the addition amount of γ-aminopropyltriethoxysilane or 3-glycidyloxypropyltrimethoxysilane to the dopamine hydrochloride solution is 3-8wt%;

[0011] Dopamine hydrochloride solution uses water as solvent and has a concentration of 5-10g / L.

[0012] Preferably, the pH is adjusted using a Tris aqueous solution with a pH of 10.

[0013] Preferably, the added amount of diatomaceous earth or zeolite is 1-3 times the mass of dopamine hydrochloride.

[0014] Preferably, the stirring speed is 50-100 rpm; and the soaking time is 20-30 h.

[0015] Preferably, the freeze-drying conditions are -30 to -10°C for 1 to 2 hours.

[0016] Preferably, the filler is at least one of fumed silica or titanium dioxide.

[0017] Preferably, the additives include a defoamer, a dispersant, a leveling agent, a wetting agent and a preservative, and the mass ratio of the defoamer, the dispersant, the leveling agent, the wetting agent and the preservative is (0.3-1.1):(0.5-1.5):(0.5-1.5):(0.7-1.2):(0.5-1).

[0018] The method for preparing any of the above-mentioned impact-resistant water-based bio-based exterior wall coatings comprises the following steps:

[0019] Mixing water, filler and additives, stirring to obtain a first blended liquid;

[0020] Adding water-based bio-based polyurethane resin to the first blended liquid and stirring to obtain a second blended liquid;

[0021] The modified porous material is added to the second mixed liquid, and stirred to obtain the coating.

[0022] Preferably, the stirring speed is 300-800 rpm.

[0023] The beneficial effects of the present invention are:

[0024] γ-aminopropyltriethoxysilane or 3-glycidyloxypropyltrimethoxysilane can undergo hydrolysis and condensation reaction with hydroxyl groups on the surface of diatomite or zeolite to form chemical bonds. This chemical bonding helps to improve the compatibility between inorganic substances and resins, thereby improving the dispersibility of diatomite and zeolite in water-based bio-based polyurethane resins. At the same time, γ-aminopropyltriethoxysilane or 3-glycidyloxypropyltrimethoxysilane itself hydrolyzes and condenses to form POSS, and dopamine hydrochloride oxidizes and self-polymerizes to form PDA. The two together form a binding layer on the surface of diatomite or zeolite. This binding layer can further promote the uniform dispersion of inorganic substances in the resin, and at the same time can also improve the bonding strength with the resin and the bonding strength between the coating and the substrate, thereby improving the impact resistance of the coating and ensuring the safety of the building. In addition, as a porous material, diatomite and zeolite themselves can effectively disperse to strengthen the physical bonding of the coating layer, making the coating more firm, less prone to bubbles or shedding, and improving the durability of the coating. DETAILED DESCRIPTION

[0025] The impact-resistant water-based bio-based exterior wall coating prepared in the following examples includes the following components by mass percentage: 12-24% water, 50-65% water-based bio-based polyurethane resin (Covestro polymer, Bayhydrol OH2592), 8-18% modified porous material, 5-10% fumed silica or titanium dioxide, and 3-8% additives (including defoamers, dispersants, leveling agents, wetting agents and preservatives, with a mass ratio of (0.3-1.1):(0.5-1.5):(0.5-1.5):(0.7-1.2):(0.5-1)).

[0026] Among them, the preparation method of the modified porous material is to first dissolve 5-10g of dopamine hydrochloride in 1L of water, then disperse γ-aminopropyltriethoxysilane or 3-glycidyloxypropyltrimethoxysilane (3-8wt%, based on the mass of the dopamine hydrochloride solution) in the above solution, adjust the pH to 8-9 with a Tris aqueous solution with a pH of 10, then add 5-30g of diatomaceous earth or 5-30g of zeolite, and soak for 20-30h under stirring at 50-100rpm; after the end, filter, wash, freeze-dry at -30 to -10°C for 1-2h, and then crush.

[0027] Example 1

[0028] The coating formula is as follows (mass percentage, %):

[0029] water 15 Dispersant 4240 1 Waterborne Bio-based Polyurethane Resins 60 Leveling agent RM-2020 1 Modified porous materials 13 Wetting agent 4100 1 Fumed Silica 8 Preservative 458 0.5 Defoamer 334 0.5 total 100

[0030] Among them, the preparation method of the modified porous material is to first dissolve 5g of dopamine hydrochloride in 1L of water, then disperse γ-aminopropyltriethoxysilane (5wt%, based on the mass of dopamine hydrochloride solution) in the above solution, adjust the pH to 8.5 with a Tris aqueous solution with a pH of 10, then add 10g of diatomaceous earth, and soak it under stirring at 50rpm for 24h; after completion, filter, wash, freeze-dry at -20℃ and then crush it.

[0031] The preparation method of the above-mentioned water-based bio-based exterior wall coating is to add water, filler and additive into a reactor, and stir them evenly at a speed of 500 rpm; then add water-based bio-based polyurethane resin, stir them evenly at a speed of 700 rpm, and then add modified porous material, and stir them evenly at a speed of 700 rpm.

[0032] Example 2

[0033] The coating formula is as follows (mass percentage, %):

[0034] water 15 Dispersant 4240 1 Waterborne Bio-based Polyurethane Resins 60 Leveling agent RM-2020 1 Modified porous materials 13 Wetting agent 4100 1 Fumed Silica 8 Preservative 458 0.5 Defoamer 334 0.5 total 100

[0035] Among them, the preparation method of the modified porous material is to first dissolve 5g of dopamine hydrochloride in 1L of water, then disperse 3-glycidyloxypropyltrimethoxysilane (5wt%, based on the mass of the dopamine hydrochloride solution) in the above solution, adjust the pH to 8.5 with a Tris aqueous solution with a pH of 10, then add 10g of diatomaceous earth, and soak it under stirring at 50rpm for 24h; after completion, filter, wash, freeze-dry at -20℃ and then crush it.

[0036] The preparation method of the above-mentioned water-based bio-based exterior wall coating is to add water, filler and additive into a reactor, and stir them evenly at a speed of 500 rpm; then add water-based bio-based polyurethane resin, stir them evenly at a speed of 700 rpm, and then add modified porous material, and stir them evenly at a speed of 700 rpm.

[0037] Comparative Example 1

[0038] It is basically the same as Example 1, except that unmodified porous material (diatomaceous earth) is used in this comparative example.

[0039] The coating formula is as follows (mass percentage, %):

[0040]

[0041]

[0042] The preparation method of the above-mentioned water-based bio-based exterior wall coating is to add water, filler and additive into a reactor, and stir them evenly at a speed of 500 rpm; then add water-based bio-based polyurethane resin, stir them evenly at a speed of 700 rpm, and then add porous material, and stir them evenly at a speed of 700 rpm.

[0043] Comparative Example 2

[0044] It is basically the same as Example 2, except that unmodified porous material (diatomaceous earth) is used in this comparative example.

[0045] The coating formula is as follows (mass percentage, %):

[0046] water 15 Dispersant 4240 1 Waterborne Bio-based Polyurethane Resins 60 Leveling agent RM-2020 1 Porous material (diatomaceous earth) 13 Wetting agent 4100 1 Fumed Silica 8 Preservative 458 0.5 Defoamer 334 0.5 total 100

[0047] The preparation method of the above-mentioned water-based bio-based exterior wall coating is to add water, filler and additive into a reactor, and stir them evenly at a speed of 500 rpm; then add water-based bio-based polyurethane resin, stir them evenly at a speed of 700 rpm, and then add porous material, and stir them evenly at a speed of 700 rpm.

[0048] Comparative Example 3

[0049] The method is basically the same as Example 1, except that a porous material (diatomaceous earth) modified with a single dopamine hydrochloride is used in this comparative example.

[0050] The coating formula is as follows (mass percentage, %):

[0051] water 15 Dispersant 4240 1 Waterborne Bio-based Polyurethane Resins 60 Leveling agent RM-2020 1 Modified porous materials 13 Wetting agent 4100 1 Fumed Silica 8 Preservative 458 0.5 Defoamer 334 0.5 total 100

[0052] Among them, the preparation method of the modified porous material is to first dissolve 5g of dopamine hydrochloride in 1L of water, adjust the pH to 8.5 with a Tris aqueous solution with a pH of 10, then add 10g of diatomaceous earth, and soak it under stirring at 50rpm for 24h; after completion, filter, wash, freeze-dry at -20℃ and then crush it.

[0053] The preparation method of the above-mentioned water-based bio-based exterior wall coating is to add water, filler and additive into a reactor, and stir them evenly at a speed of 500 rpm; then add water-based bio-based polyurethane resin, stir them evenly at a speed of 700 rpm, and then add modified porous material, and stir them evenly at a speed of 700 rpm.

[0054] Comparative Example 4

[0055] The comparative example is basically the same as Example 1, except that a porous material (diatomaceous earth) modified with a single γ-aminopropyltriethoxysilane is used in this comparative example.

[0056] The coating formula is as follows (mass percentage, %):

[0057] water 15 Dispersant 4240 1 Waterborne Bio-based Polyurethane Resins 60 Leveling agent RM-2020 1 Modified porous materials 13 Wetting agent 4100 1 Fumed Silica 8 Preservative 458 0.5 Defoamer 334 0.5 total 100

[0058] Among them, the preparation method of the modified porous material is to disperse 50.25g of γ-aminopropyltriethoxysilane in water, adjust the pH to 8.5 with a Tris aqueous solution with a pH of 10, then add 10g of diatomaceous earth, and soak it under stirring at 50rpm for 24h; after completion, filter, wash, freeze-dry at -20℃ and then crush it.

[0059] The preparation method of the above-mentioned water-based bio-based exterior wall coating is to add water, filler and additive into a reactor, and stir them evenly at a speed of 500 rpm; then add water-based bio-based polyurethane resin, stir them evenly at a speed of 700 rpm, and then add modified porous material, and stir them evenly at a speed of 700 rpm.

[0060] Performance Testing

[0061] The coatings prepared in Examples 1-2 and Comparative Examples 1-4 were respectively coated on hot-dip galvanized steel plates to carry out impact resistance (GB / T 1732) and adhesion performance (GB / T 1720) tests. The results are shown in Table 1.

[0062] Table 1 Impact resistance and adhesion test results of the coatings prepared in Examples 1-2 and Comparative Examples 1-4

[0063]

[0064] It can be seen from Table 1 that the modified porous material added to the coating system can effectively improve the impact resistance and adhesion of the coating. The reason is that the modified porous material has good dispersibility in the resin system. The presence of the bonding layer promotes the uniform dispersion of inorganic matter in the resin and improves the bonding strength with the resin and the bonding strength between the coating and the substrate, which can further improve the impact resistance and adhesion of the coating.

Claims

1. An impact-resistant water-based bio-based exterior wall coating, characterized in that: The invention comprises the following components by mass percentage: 12-24% water, 50-65% water-based bio-based polyurethane resin, 8-18% modified porous material, 5-10% filler and 3-8% auxiliary agent; Wherein, the preparation method of the modified porous material is: Disperse γ-aminopropyltriethoxysilane or 3-glycidyloxypropyltrimethoxysilane in a dopamine hydrochloride solution, adjust the pH to 8-9, add diatomaceous earth or zeolite, and soak under stirring; after the end, filter, wash, freeze-dry and crush to obtain a modified porous material.

2. The impact-resistant water-based bio-based exterior wall paint according to claim 1, characterized in that: The addition amount of γ-aminopropyltriethoxysilane or 3-glycidyloxypropyltrimethoxysilane in the dopamine hydrochloride solution is 3-8wt%; Dopamine hydrochloride solution uses water as solvent and has a concentration of 5-10g / L.

3. The impact-resistant water-based bio-based exterior wall paint according to claim 1, characterized in that: The pH was adjusted using a Tris aqueous solution at pH = 10.

4. The impact-resistant water-based bio-based exterior wall paint according to claim 1, characterized in that: The amount of diatomaceous earth or zeolite added is 1-3 times the mass of dopamine hydrochloride.

5. The impact-resistant water-based bio-based exterior wall paint according to claim 1, characterized in that: The stirring speed is 50-100 rpm; The soaking time is 20-30h.

6. The impact-resistant water-based bio-based exterior wall paint according to claim 1, characterized in that: The freeze-drying conditions are -30 to -10°C for 1 to 2 hours.

7. The impact-resistant water-based bio-based exterior wall paint according to claim 1, characterized in that: The filler is at least one of fumed silica or titanium dioxide.

8. The impact-resistant water-based bio-based exterior wall paint according to claim 1, characterized in that: The additives include defoamer, dispersant, leveling agent, wetting agent and preservative, and the mass ratio of the defoamer, dispersant, leveling agent, wetting agent and preservative is (0.3-1.1):(0.5-1.5):(0.5-1.5):(0.7-1.2):(0.5-1).

9. The method for preparing the impact-resistant water-based bio-based exterior wall coating according to any one of claims 1 to 8, characterized in that: The steps include: Mixing water, filler and additives, stirring to obtain a first blended liquid; Adding water-based bio-based polyurethane resin to the first blended liquid and stirring to obtain a second blended liquid; The modified porous material is added to the second mixed liquid, and stirred to obtain the coating; the stirring speed is 300-800 rpm.

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