Self-crosslinking exterior wall coating containing reinforcing fiber and preparation method thereof

Abstract

The invention discloses a self-crosslinking exterior wall coating containing reinforcing fibers and a preparation method thereof. The coating comprises the following components by mass: 10-20% water, 0.1-0.5% bentonite, 0.1-0.5% cellulose, 3-8% reinforcing fibers, 0.5-2% ethylene glycol, 0.5-1.5% dispersant, 0.1-0.5% wetting agent, 0.1-0.3% multifunctional additive, 15-25% titanium dioxide, 8-15% precipitated barium sulfate, 2-8% silane-modified nano-silica, 5-10% water-based polyurethane emulsion, 30-40% organosilicon-modified acrylic emulsion, 1-3% film-forming aid, 0.1-0.3% bactericide, 0.1-0.2% preservative, 0.5-1% mildew inhibitor, 0.3-1.1% defoaming agent, and 0.5-1.8% leveling agent. By compounding silicone-modified acrylic emulsion and water-based polyurethane emulsion, and adding silane-modified nano-silica and reinforcing fibers, the coating has excellent resistance to artificial weathering, wear resistance, impact resistance, corrosion resistance and high hardness.

Description

Technical Field

[0001] The invention relates to a self-crosslinking exterior wall paint containing reinforcing fibers and a preparation method thereof, belonging to the technical field of paints. Background Art

[0002] Exterior wall paints offer rich decorative colors, are easy to apply, and can express a variety of architectural styles. With the development of my country's economy and the improvement of people's living standards, latex paint, which is safe, low-carbon, and environmentally friendly, has become the main material for building finishes in my country. It is also an exterior wall finishing material that the country strongly advocates and promotes.

[0003] Low coating hardness, weak adhesion, and easy powdering and shedding are common problems with exterior wall coatings, significantly hindering their widespread application. Weather resistance remains a technical challenge, particularly in areas with severe air pollution. The key to addressing the current challenges of low hardness and poor weather resistance in exterior wall coatings is to rationally utilize existing advanced anti-fouling technology to develop high-hardness, weather-resistant coatings.

[0004] At present, some solvent-based exterior wall paints are used to solve the problem of weather resistance, but they are not environmentally friendly. There are also some two-component polyurethane paints, which have excellent performance, but the cost is too high, which greatly limits the promotion and application of such products. Summary of the Invention

[0005] The present invention aims to provide a self-crosslinking exterior wall paint containing reinforcing fibers and a preparation method thereof. The compounding of an organosilicon-modified acrylic emulsion and an aqueous polyurethane emulsion, and the addition of silane-modified nano-silica and reinforcing fibers enable the coating to have excellent resistance to artificial weathering, wear resistance, impact resistance, corrosion resistance and high hardness.

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

[0007] A self-crosslinking exterior wall paint containing reinforcing fibers, comprising the following components by mass:

[0008] Water 10-20%, bentonite 0.1-0.5%, cellulose 0.1-0.5%, reinforcing fiber 3-8%, ethylene glycol 0.5-2%, dispersant 0.5-1.5%, wetting agent 0.1-0.5%, multifunctional additive 0.1-0.3%, titanium dioxide 15-25%, precipitated barium sulfate 8-15%, silane-modified nano-silica 2-8%, water-based polyurethane emulsion 5-10%, silicone-modified acrylic emulsion 30-40%, film-forming aid 1-3%, bactericide 0.1-0.3%, preservative 0.1-0.2%, mildew inhibitor 0.5-1%, defoamer 0.3-1.1%, leveling agent 0.5-1.8%.

[0009] Preferably, the reinforcing fiber is prepared by: melting aminosulfonic acid and urea together and then adding lignin to obtain a mixed solution; dispersing the mixed solution in deionized water added with matrix fiber, stirring, centrifuging, washing, and drying to obtain the reinforcing fiber.

[0010] Preferably, the aminosulfonic acid and urea are eutectic at a molar ratio of 1:(2-5) at 75-95°C;

[0011] In the mixed solution, the mass fraction of lignin is 5-12%.

[0012] Preferably, the matrix fiber is one or more combinations of alumina fiber, aluminum silicate fiber and mullite fiber.

[0013] Preferably, the mass ratio of the matrix fiber in the deionized water to the lignin in the mixed solution is 1:(1-3).

[0014] Preferably, the centrifugation condition is 8000-12000 rpm, 5-10 min; the drying condition is 40-60° C., 15-30 min.

[0015] Preferably, the preparation method of the organosilicon-modified acrylic emulsion is: cyclosiloxane, allyl hydroxyethyl ether, acrylic acid, and an emulsifier are added to deionized water and mixed, and then ammonium persulfate is intermittently added dropwise to carry out soap-free emulsion polymerization.

[0016] Preferably, the weight proportions of the cyclosiloxane, allyl hydroxyethyl ether, acrylic acid, ammonium persulfate, deionized water and emulsifier are 35-55 parts, 15-25 parts, 15-25 parts, 0.2-2 parts, 3-5 parts and 15-20 parts respectively.

[0017] Preferably, the conditions for the soap-free emulsion polymerization are: temperature 80-90° C., reaction time 3-6 h.

[0018] The method for preparing any of the above-mentioned self-crosslinking exterior wall coatings containing reinforcing fibers comprises the following steps:

[0019] Mixing water, bentonite, cellulose, ethylene glycol, a dispersant, a wetting agent, and a portion of a defoamer, and stirring to obtain a first blend;

[0020] adding a multifunctional additive to the first blend and stirring to obtain a second blend;

[0021] Add titanium dioxide and precipitated barium sulfate to the second blend, and stir until the fineness is less than 50 μm to obtain a third blend;

[0022] Adding reinforcing fiber, silane-modified nano-silica, aqueous polyurethane emulsion, silicone-modified acrylic emulsion, film-forming aid, fungicide, preservative, mildewcide, and remaining defoamer to the third blend and stirring to obtain a fourth blend;

[0023] A leveling agent is added to the fourth blend, and the mixture is stirred to obtain the exterior wall coating.

[0024] The beneficial effects of the present invention are:

[0025] 1. Silicone-modified acrylic emulsion has a hyperbranched structure and strong intermolecular forces, resulting in a higher viscosity, which helps improve the uniformity and smoothness of the coating and reduce the leveling time and coating thickness during brushing. The hyperbranched structure has a longer main chain and a highly branched structure, which gives it strong antioxidant and UV radiation resistance, helping to improve the weather resistance of the coating and enable it to maintain good appearance and performance in outdoor environments. In addition, the hyperbranched polymer has a large molecular weight and a complex branched structure, so it has strong wear resistance and impact resistance, which helps to improve the wear resistance and impact resistance of the coating.

[0026] Waterborne polyurethane emulsions offer excellent weather resistance, abrasion resistance, impact resistance, chemical resistance, and bonding strength. Weather resistance means the coating can effectively withstand the effects of the outdoor environment, maintaining its appearance and performance. Furthermore, their excellent abrasion and impact resistance effectively protect the coated surface from wear and scratches. Furthermore, their excellent adhesion and permeability allow them to effectively fill and repair minor surface irregularities and cracks, enhancing the coating's integrity and aesthetics.

[0027] Therefore, by compounding silicone-modified acrylic emulsion with water-based polyurethane emulsion, the weather resistance, wear resistance and impact resistance of the coating can be improved.

[0028] 2. Add silane-modified nano-silica as a special additive to the components. Silane-modified nano-silica has the hydrophilic and high hardness properties of inorganic substances. At the same time, its own nanostructure can be effectively dispersed between the particles of the film-forming material, which can improve the scratch resistance, wear resistance and hardness of the coating, thereby improving the hardness of the coating.

[0029] 3. By adding reinforcing fibers to the components, the amino-lignin nanoparticles in the reinforcing fibers can be coated on the surface of the matrix fibers. On the one hand, the dispersibility of the matrix fibers can be improved, and the matrix fibers can be used to improve the high temperature resistance, corrosion resistance, thermal insulation and mechanical properties of the coating; on the other hand, the UV shielding effect of the amino-lignin nanoparticles on the surface of the matrix fibers can be used to improve the weather resistance of the coating. DETAILED DESCRIPTION

[0030] The present invention will be specifically described below with reference to the embodiments.

[0031] Example 1

[0032] The coating components are as follows (unit: %):

[0033]

[0034]

[0035] Among them, the preparation method of the reinforcing fiber is as follows: aminosulfonic acid and urea are eutectic at a molar ratio of 1:3 at 85°C, and then lignin is added to obtain a mixed solution (5wt% lignin); the mixed solution is dispersed in deionized water added with aluminum silicate fiber (the mass ratio of aluminum silicate fiber to lignin is 1:3), stirred at 600 rpm for 30 minutes, and then centrifuged at 10,000 rpm for 5 minutes in a centrifuge. The lower layer is removed and washed to neutrality, and then dried at 55°C for 20 minutes to obtain the reinforcing fiber.

[0036] The preparation method of the silicone-modified acrylic emulsion is as follows: 35 parts of cyclosiloxane, 22 parts of allyl hydroxyethyl ether, 18 parts of acrylic acid, and 4.5 parts of an emulsifier are added to 18 parts of deionized water and mixed evenly to obtain a pre-emulsion; 0.5 parts of ammonium persulfate are dissolved in 2 parts of deionized water to obtain an ammonium persulfate solution; the ammonium persulfate solution is intermittently added dropwise to the pre-emulsion at 85° C., and the mixture is reacted for 5 hours after the addition is completed.

[0037] The preparation method of exterior wall coating comprises the following steps:

[0038] S1. Add water, bentonite, cellulose, ethylene glycol, dispersant, wetting agent and defoamer 334 into the reactor in sequence and stir evenly at a speed of 500 rpm;

[0039] S2. Add the multifunctional additive to the above reactor and stir at a speed of 1200 rpm for 5 min;

[0040] S3, adding titanium dioxide and precipitated barium sulfate into the above reactor, stirring at a speed of 1500 rpm for 15 minutes until the fineness is less than 50 μm;

[0041] S4, adding reinforcing fiber, silane-modified nano-silica, water-based polyurethane emulsion, silicone-modified acrylic emulsion, film-forming aid, bactericide, preservative, mildew inhibitor, and defoamer A10 to the above-mentioned reactor, and stirring at a speed of 1200 rpm for 10 min;

[0042] S5. Add the leveling agent into the above reactor and stir evenly at a speed of 800 rpm.

[0043] Example 2

[0044] The coating components are as follows (unit: %):

[0045]

[0046]

[0047] Among them, the preparation method of the reinforcing fiber is as follows: aminosulfonic acid and urea are eutectic at a molar ratio of 1:3 at 85°C, and then lignin is added to obtain a mixed solution (8wt% lignin); the mixed solution is dispersed in deionized water added with aluminum silicate fiber (the mass ratio of aluminum silicate fiber to lignin is 1:3), stirred at 600 rpm for 30 minutes, and then centrifuged at 10,000 rpm for 5 minutes in a centrifuge. The lower layer is removed and washed to neutrality, and then dried at 55°C for 20 minutes to obtain the reinforcing fiber.

[0048] The preparation method of the silicone-modified acrylic emulsion is as follows: 40 parts of cyclosiloxane, 18 parts of allyl hydroxyethyl ether, 17 parts of acrylic acid, and 4.5 parts of an emulsifier are added to 18 parts of deionized water and mixed evenly to obtain a pre-emulsion; 0.5 parts of ammonium persulfate are dissolved in 2 parts of deionized water to obtain an ammonium persulfate solution; the ammonium persulfate solution is intermittently added dropwise to the pre-emulsion at 85° C., and the mixture is reacted for 5 hours after the addition is completed.

[0049] The preparation method of exterior wall coating comprises the following steps:

[0050] S1. Add water, bentonite, cellulose, ethylene glycol, dispersant, wetting agent and defoamer 334 into the reactor in sequence and stir evenly at a speed of 500 rpm;

[0051] S2. Add the multifunctional additive to the above reactor and stir at a speed of 1200 rpm for 5 min;

[0052] S3, adding titanium dioxide and precipitated barium sulfate into the above reactor, stirring at a speed of 1500 rpm for 15 minutes until the fineness is less than 50 μm;

[0053] S4, adding reinforcing fiber, silane-modified nano-silica, water-based polyurethane emulsion, silicone-modified acrylic emulsion, film-forming aid, bactericide, preservative, mildew inhibitor, and defoamer A10 to the above-mentioned reactor, and stirring at a speed of 1200 rpm for 10 min;

[0054] S5. Add the leveling agent into the above reactor and stir evenly at a speed of 800 rpm.

[0055] Example 3

[0056] The coating components are as follows (unit: %):

[0057]

[0058]

[0059] Among them, the preparation method of the reinforcing fiber is as follows: aminosulfonic acid and urea are eutectic at a molar ratio of 1:3 at 85°C, and then lignin is added to obtain a mixed solution (10wt% lignin); the mixed solution is dispersed in deionized water added with aluminum silicate fiber (the mass ratio of aluminum silicate fiber to lignin is 1:3), stirred at 600 rpm for 30 minutes, and then centrifuged at 10,000 rpm for 5 minutes in a centrifuge. The lower layer is removed and washed to neutrality, and then dried at 55°C for 20 minutes to obtain the reinforcing fiber.

[0060] The preparation method of the silicone-modified acrylic emulsion is as follows: 40 parts of cyclosiloxane, 20 parts of allyl hydroxyethyl ether, 15 parts of acrylic acid, and 4.5 parts of an emulsifier are added to 18 parts of deionized water and mixed evenly to obtain a pre-emulsion; 0.5 parts of ammonium persulfate are dissolved in 2 parts of deionized water to obtain an ammonium persulfate solution; the ammonium persulfate solution is intermittently added dropwise to the pre-emulsion at 85° C., and the mixture is reacted for 5 hours after the addition is completed.

[0061] The preparation method of exterior wall coating comprises the following steps:

[0062] S1. Add water, bentonite, cellulose, ethylene glycol, dispersant, wetting agent and defoamer 334 into the reactor in sequence and stir evenly at a speed of 500 rpm;

[0063] S2. Add the multifunctional additive to the above reactor and stir at a speed of 1200 rpm for 5 min;

[0064] S3, adding titanium dioxide and precipitated barium sulfate into the above reactor, stirring at a speed of 1500 rpm for 15 minutes until the fineness is less than 50 μm;

[0065] S4, adding reinforcing fiber, silane-modified nano-silica, water-based polyurethane emulsion, silicone-modified acrylic emulsion, film-forming aid, bactericide, preservative, mildew inhibitor, and defoamer A10 to the above-mentioned reactor, and stirring at a speed of 1200 rpm for 10 min;

[0066] S5. Add the leveling agent into the above reactor and stir evenly at a speed of 800 rpm.

[0067] Comparative Example 1

[0068] The difference from Example 3 is that the lignin in the reinforcing fibers is not subjected to amination treatment.

[0069] The preparation method of the reinforcing fiber is as follows: lignin and aluminum silicate fiber are dispersed in deionized water in a mass ratio of 3:1, stirred at 600 rpm for 30 minutes, and then centrifuged at 10,000 rpm for 5 minutes in a centrifuge, the lower layer is removed and washed to neutrality, and then dried at 55°C for 20 minutes to obtain the reinforcing fiber.

[0070] The coating components are as follows (unit: %):

[0071]

[0072] The preparation method of exterior wall coating comprises the following steps:

[0073] S1. Add water, bentonite, cellulose, ethylene glycol, dispersant, wetting agent and defoamer 334 into the reactor in sequence and stir evenly at a speed of 500 rpm;

[0074] S2. Add the multifunctional additive to the above reactor and stir at a speed of 1200 rpm for 5 min;

[0075] S3, adding titanium dioxide and precipitated barium sulfate into the above reactor, stirring at a speed of 1500 rpm for 15 minutes until the fineness is less than 50 μm;

[0076] S4, adding reinforcing fiber, silane-modified nano-silica, water-based polyurethane emulsion, silicone-modified acrylic emulsion, film-forming aid, bactericide, preservative, mildew inhibitor, and defoamer A10 to the above-mentioned reactor, and stirring at a speed of 1200 rpm for 10 min;

[0077] S5. Add the leveling agent into the above reactor and stir evenly at a speed of 800 rpm.

[0078] Comparative Example 2

[0079] The difference from Example 3 is that pure aluminum silicate fiber is added to the coating component of Comparative Example 2 instead of reinforcing fiber.

[0080] The coating components are as follows (unit: %):

[0081]

[0082] The preparation method of exterior wall coating comprises the following steps:

[0083] S1. Add water, bentonite, cellulose, ethylene glycol, dispersant, wetting agent and defoamer 334 into the reactor in sequence and stir evenly at a speed of 500 rpm;

[0084] S2. Add the multifunctional additive to the above reactor and stir at a speed of 1200 rpm for 5 min;

[0085] S3, adding titanium dioxide and precipitated barium sulfate into the above reactor, stirring at a speed of 1500 rpm for 15 minutes until the fineness is less than 50 μm;

[0086] S4, adding aluminum silicate fiber, silane-modified nano-silica, water-based polyurethane emulsion, silicone-modified acrylic emulsion, film-forming aid, bactericide, preservative, mildew inhibitor, and defoamer A10 to the above-mentioned reactor, and stirring at a speed of 1200 rpm for 10 min;

[0087] S5. Add the leveling agent into the above reactor and stir evenly at a speed of 800 rpm.

[0088] The coatings obtained in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the test criteria were as follows: the state in the container, low-temperature stability, workability, drying time, coating appearance, water resistance, coating temperature deformation resistance, water permeability, resistance to artificial weathering, chalking, and discoloration were all performed in accordance with GB / T 9755-2014; the bonding strength was performed in accordance with JC / T 2217-2014; the high and low temperature cycle test was performed in accordance with Note 1; the impact resistance was performed in accordance with GB / T 1732-2020; the hardness was performed in accordance with GB / T 6739-2006; the chemical resistance (acid and alkali) was performed in accordance with GB / T 9274; and the wear resistance was performed in accordance with GB / T 1768-2006.

[0089] The test results are shown in Table 1.

[0090] Table 1:

[0091]

[0092]

[0093] Note 1: High and low temperature cyclic test conditions: 80±2℃, 95% RH 4h, 80℃ to -40℃ 2h (temperature change rate 1℃ / min), -40±2℃ 4h, -40℃ to 80℃, 95% RH 2h (temperature change rate 1℃ / min), 12h as one cycle. After the 60-cycle test, the sample should be placed at room temperature for more than 16h before testing again. When the coating thickness is ≤300μm, the cross-cut test is carried out. When the thickness is ≤80μm, the cross-cut spacing is 1mm. When the thickness is 80-150μm, the cross-cut spacing is 2mm. When the thickness is 150-300μm, the cross-cut spacing is 3mm. When the coating thickness is greater than 300μm, the X-cut test is carried out. The adhesion is not less than level 3.

[0094] As can be seen from the data in Table 1, the coatings provided in Examples 1-3 have excellent resistance to artificial weathering, wear resistance, impact resistance, corrosion resistance and high hardness. Therefore, it can be seen that the compounding of the silicone-modified acrylic emulsion and the aqueous polyurethane emulsion, as well as the addition of silane-modified nano-silica and reinforcing fibers, have a positive effect on improving the performance of the coating. The artificial weathering resistance, wear resistance, impact resistance, corrosion resistance and high hardness of the coatings provided in Examples 1-3 are better than the corresponding performance of the coatings provided in Comparative Examples 1-2. The reason is that the amino-lignin nanoparticles can be better coated on the surface of the matrix fiber, thereby improving the dispersibility of the matrix fiber. While utilizing the matrix fiber to improve the high temperature resistance, corrosion resistance and thermal insulation performance of the coating, the highly dispersed matrix fiber can better improve the wear resistance and impact resistance of the coating; secondly, the ultraviolet shielding effect of the amino-lignin nanoparticles on the surface of the matrix fiber also improves the weather resistance (resistance to artificial weathering, resistance to neutral salt spray) of the coating.

[0095] The above is only a preferred embodiment of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. A self-crosslinking exterior wall coating containing reinforcing fibers, characterized in that: Includes the following components by mass fraction: Water 10-20%, bentonite 0.1-0.5%, cellulose 0.1-0.5%, reinforcing fiber 3-8%, ethylene glycol 0.5-2%, dispersant 0.5-1.5%, wetting agent 0.1-0.5%, multifunctional additive AMP-95 0.1-0.3%, titanium dioxide 15-25%, precipitated barium sulfate 8-15%, silane-modified nano-silica 2-8%, water-based polyurethane emulsion 5-10%, silicone-modified acrylic emulsion 30-40%, film-forming agent 1-3%, bactericide 0.1-0.3%, preservative 0.1-0.2%, mildew inhibitor 0.5-1%, defoamer 0.3-1.1%, leveling agent 0.5-1.8%; The preparation method of the reinforcing fiber is as follows: sulfamic acid and urea are co-melted and then lignin is added to obtain a mixed solution; the mixed solution is dispersed in deionized water added with matrix fiber, stirred, centrifuged, washed, and dried to obtain the reinforcing fiber.

2. The self-crosslinking exterior wall paint containing reinforcing fibers according to claim 1, characterized in that: The aminosulfonic acid and urea are heated to form a co-melt at a molar ratio of 1:(2-5) at 75-95°C; In the mixed solution, the mass fraction of lignin is 5-12%.

3. The self-crosslinking exterior wall paint containing reinforcing fibers according to claim 1, characterized in that: The matrix fiber is one or more combinations of alumina fiber, aluminum silicate fiber and mullite fiber.

4. The self-crosslinking exterior wall paint containing reinforcing fibers according to claim 1, characterized in that: The mass ratio of the matrix fiber in the deionized water to the lignin in the mixed solution is 1:(1-3).

5. The self-crosslinking exterior wall paint containing reinforcing fibers according to claim 1, characterized in that: The centrifugal conditions are 8000-12000 rpm, 5-10 min; the drying conditions are 40-60° C., 15-30 min.

6. The self-crosslinking exterior wall paint containing reinforcing fibers according to claim 1, characterized in that: The preparation method of the organosilicon-modified acrylic emulsion is as follows: cyclosiloxane, allyl hydroxyethyl ether, acrylic acid and emulsifier are added into deionized water and mixed, and then ammonium persulfate is added dropwise intermittently to carry out soap-free emulsion polymerization.

7. The self-crosslinking exterior wall paint containing reinforcing fibers according to claim 6, characterized in that: The conditions of the soap-free emulsion polymerization are: temperature 80-90° C., reaction time 3-6 hours.

8. The method for preparing the self-crosslinking exterior wall coating containing reinforcing fibers according to any one of claims 1 to 7, characterized in that: The steps include: Mixing water, bentonite, cellulose, ethylene glycol, a dispersant, a wetting agent, and a portion of a defoamer, and stirring to obtain a first blend; Adding the multifunctional additive AMP-95 to the first blend and stirring to obtain a second blend; Add titanium dioxide and precipitated barium sulfate to the second blend, and stir until the fineness is less than 50 μm to obtain a third blend; Adding reinforcing fiber, silane-modified nano-silica, aqueous polyurethane emulsion, silicone-modified acrylic emulsion, film-forming aid, fungicide, preservative, mildewcide, and remaining defoamer to the third blend and stirring to obtain a fourth blend; A leveling agent is added to the fourth blend, and the mixture is stirred to obtain the exterior wall coating.

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