Modified silica powder and application thereof in external wall thermal insulation coating

Abstract

The invention discloses modified silica powder and application thereof in an external wall heat insulation coating, and the modified silica powder is characterized by comprising the following components in parts by weight: 90-100 parts of silica powder, 3-5 parts of gamma-methacryloxypropyltrimethoxysilane, 1-2 parts of stearic acid, 2-3 parts of nano titanium dioxide and 2-4 parts of polyethylene glycol. The invention belongs to the technical field of silica powder application, and particularly relates to modified silica powder and application of the modified silica powder in an outer wall heat insulation coating.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon micropowder application, and specifically refers to modified silicon micropowder and application thereof in exterior wall thermal insulation coating. Background Art

[0002] As the global energy crisis intensifies and people's requirements for building energy conservation and comfort continue to increase, exterior wall thermal insulation coatings have received widespread attention as an effective energy-saving material. Exterior wall thermal insulation coatings can reduce the cooling energy consumption of buildings in summer and the heating energy consumption in winter, which is of great significance for reducing energy consumption and greenhouse gas emissions.

[0003] In the existing exterior wall thermal insulation coating technology, silicon micropowder has been widely studied and applied as a potential functional filler. Silicon micropowder has the advantages of low cost, wide source, and good chemical stability. However, there are some significant problems when ordinary silicon micropowder is used in exterior wall thermal insulation coatings: on the one hand, silicon micropowder has poor compatibility with organic film-forming substances (such as emulsions, etc.) in the coating. Since the surface of silicon micropowder has strong hydrophilicity and high surface energy, it is easy to agglomerate in the coating system and difficult to disperse evenly. This agglomeration phenomenon will lead to a decrease in the stability of the coating, such as stratification, precipitation and other problems, and will affect the construction performance of the coating, causing defects on the coating surface and reducing the coating quality; on the other hand, the thermal insulation performance of ordinary silicon micropowder itself needs to be further improved. Pure silicon micropowder has limited reflection and absorption capacity for solar radiation and cannot effectively prevent the transfer of heat on the wall surface. In practical applications, the thermal insulation effect of exterior wall thermal insulation coatings that only use unmodified silicon micropowder as filler cannot meet the increasingly stringent building energy-saving standards.

[0004] Although some existing improvement methods have alleviated the above problems to a certain extent, they still have limitations. Among them, the dispersibility of silica micropowder is improved by adding a large amount of dispersant, but this will increase the cost of the coating and may have a negative impact on other properties of the coating, such as reducing the hardness and water resistance of the coating. There are also some methods that modify the silica micropowder by simple physical mixing, but the modification effect is not long-lasting. During long-term use, the performance of silica micropowder will gradually degrade, affecting the thermal insulation and protective properties of the coating. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a modified silica powder and its application in exterior wall thermal insulation coating.

[0006] In order to achieve the above functions, the technical solution adopted by the present invention is as follows: a modified silicon micropowder, whose formula composition by weight is: 90-100 parts of silicon micropowder, 3-5 parts of γ-methacryloxypropyltrimethoxysilane, 1-2 parts of stearic acid, 2-3 parts of nano titanium dioxide, and 2-4 parts of polyethylene glycol.

[0007] Preferably, the silicon micropowder has a particle size of 1-10 μm and a purity of ≥99%.

[0008] The present invention discloses a method for preparing modified silicon micropowder, comprising the following steps:

[0009] (i) Mixing pretreatment: Add silicon micropowder, stearic acid and polyethylene glycol into a high-speed mixer in proportion, mix at a speed of 800-1000r / min for 15-20 minutes to make the ingredients preliminarily evenly mixed, and control the mixing temperature at 40-50°C. This step can make stearic acid and polyethylene glycol better adhere to the surface of silicon micropowder and improve the subsequent reaction activity;

[0010] (ii) Modification reaction: transfer the mixture of step (i) to a reaction kettle, add γ-methacryloxypropyltrimethoxysilane and nano-titanium dioxide, stir at a stirring speed of 200-300r / min under nitrogen protection, and heat to 70-80°C for 3-4 hours. Nitrogen protection can prevent the coupling agent and other components from oxidizing at high temperatures, thus ensuring the modification effect;

[0011] (III) Post-treatment: After the reaction is completed, cool naturally to room temperature, then wash with anhydrous ethanol 2-3 times to remove unreacted substances, and finally vacuum dry at 60-70°C for 2-3 hours.

[0012] Modified silicon powder is obtained.

[0013] The invention discloses an application of modified silicon micropowder in an exterior wall thermal insulation coating. The exterior wall thermal insulation coating comprises the following formula in parts by weight: 20-30 parts of modified silicon micropowder, 30-40 parts of pure acrylic emulsion, 10-15 parts of hollow glass microspheres, 10-12 parts of rutile titanium dioxide, 0.5-1 part of sodium hexametaphosphate, 0.2-0.5 parts of an organosilicon defoamer, 0.8-1.2 parts of hydroxyethyl cellulose and 20-30 parts of deionized water.

[0014] The present invention discloses an application of modified silicon micropowder in exterior wall thermal insulation coating. The preparation method of the exterior wall thermal insulation coating comprises the following steps:

[0015] (i) Preparation of dispersion: adding sodium hexametaphosphate to a portion of deionized water, stirring at a stirring speed of 400-500 r / min until completely dissolved to form a dispersion;

[0016] (ii) Premixing: Add pure acrylic emulsion and silicone defoamer to the dispersion and stir at a stirring speed of 600-800 r / min for 10-15 minutes to preliminarily mix the ingredients;

[0017] (III) Mixing and filling: slowly add modified silica powder, hollow glass microspheres and rutile titanium dioxide into the above-mentioned mixed solution, increase the stirring speed to 1000-1200 r / min, and stir for 20-30 minutes to fully disperse the solid particles in the mixed solution;

[0018] (iv) Thickening adjustment: Add hydroxyethyl cellulose and continue stirring for 10-15 minutes, then use the remaining deionized water to adjust the viscosity of the coating to an appropriate range (80-100s measured by a Tu-4 viscometer).

[0019] The present invention adopts the above structure to achieve the following beneficial effects:

[0020] 1. The silicon micropowder is modified by adding γ-methacryloxypropyltrimethoxysilane, stearic acid and polyethylene glycol, thereby overcoming the problem of poor compatibility between ordinary silicon micropowder and organic film-forming substances in the coating. The modified silicon micropowder can be better integrated into the coating system, reducing agglomeration, and effectively avoiding stability problems such as coating stratification and precipitation caused by silicon micropowder agglomeration, ensuring the quality stability of the coating during storage and use, and extending the service life of the coating. At the same time, the evenly dispersed silicon micropowder can make the coating construction smoother, reduce coating surface defects, improve coating quality, and ensure the construction effect. Whether it is brushing, roller coating or spraying, a more uniform and beautiful coating can be obtained; avoiding the method of improving the dispersibility of silicon micropowder by adding a large amount of dispersant, thereby reducing the cost of coatings, and also avoiding the negative impact of excessive dispersant on other properties such as coating hardness and water resistance.

[0021] 2. Compared with ordinary silicon micropowder, the modified silicon micropowder of the present invention significantly improves the reflection and absorption capacity of solar radiation, more effectively prevents the transfer of heat on the wall surface, meets the increasingly stringent building energy-saving standards, and is applied to exterior wall thermal insulation coatings, which can significantly enhance the thermal insulation performance of the coating, reduce indoor and outdoor heat exchange, reduce the building's dependence on temperature control equipment such as air conditioners, and reduce energy consumption; each step in the coating preparation process, including dispersion preparation, premixing, mixing filling and thickening adjustment, has clear parameters and is easy to control. This stable process ensures the consistency and stability of the quality of each batch of coatings, which is conducive to large-scale production. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for preparing modified silicon micropowder comprises the following steps:

[0025] (i) Mixing pretreatment: accurately weigh 100 g of silicon micropowder with a particle size of 1-10 μm and a purity of 99%, 1 g of stearic acid, and 2 g of polyethylene glycol, add them into a high-speed mixer, set the speed to 800 r / min, and mix at 40° C. for 20 minutes to preliminarily evenly mix the ingredients;

[0026] (ii) Modification reaction: the mixture of step (i) was transferred to a reaction kettle, 3 g of γ-methacryloxypropyltrimethoxysilane and 2 g of nano-titanium dioxide were added, nitrogen was introduced for protection, the mixture was stirred at a stirring speed of 200 r / min, and the temperature was raised to 70°C for reaction for 4 hours;

[0027] (III) Post-treatment: After the reaction is completed, the mixture is naturally cooled to room temperature, then washed twice with anhydrous ethanol to remove unreacted substances, and finally vacuum dried at 60°C for 3 hours to obtain modified silicon micropowder.

[0028] A method for preparing an exterior wall thermal insulation coating comprises the following steps:

[0029] (i) Preparation of dispersion: 0.5 g of sodium hexametaphosphate was weighed and added to 10 g of deionized water, and stirred at a stirring speed of 400 r / min until it was completely dissolved to form a dispersion;

[0030] (ii) Premixing: Add 30 g pure acrylic emulsion and 0.2 g silicone defoamer into the dispersion and stir at a stirring speed of 600 r / min for 15 minutes to preliminarily mix the ingredients;

[0031] (III) Mixing and filling: slowly add 20g of modified silica powder, 10g of hollow glass microspheres and 10g of rutile titanium dioxide into the above mixed solution, increase the stirring speed to 1000r / min, and stir for 30 minutes to fully disperse the solid particles in the mixed solution;

[0032] (iv) Thickening adjustment: add 0.8 g of hydroxyethyl cellulose, continue stirring for 15 minutes, and then use the remaining 10 g of deionized water to adjust the viscosity of the coating to an appropriate range (80 seconds as measured by a Tu-4 viscometer).

[0033] Example 2

[0034] A method for preparing modified silicon micropowder comprises the following steps:

[0035] (i) Mixing pretreatment: Weigh 100 g of silicon micropowder with a particle size of 1-10 μm and a purity of 99.5%, 2 g of stearic acid, and 4 g of polyethylene glycol, add them into a high-speed mixer, set the speed to 1000 r / min, and mix at 50° C. for 15 minutes to preliminarily evenly mix the ingredients;

[0036] (ii) Modification reaction: the mixture of step (i) was transferred to a reaction kettle, 5 g of γ-methacryloxypropyltrimethoxysilane and 3 g of nano-titanium dioxide were added, nitrogen was introduced for protection, the mixture was stirred at a stirring speed of 300 r / min, and the temperature was raised to 80°C for reaction for 3 hours;

[0037] (III) Post-treatment: After the reaction is completed, the mixture is naturally cooled to room temperature, then washed with anhydrous ethanol for 3 times to remove unreacted substances, and finally vacuum dried at 70°C for 2 hours to obtain modified silicon micropowder.

[0038] A method for preparing an exterior wall thermal insulation coating comprises the following steps:

[0039] (i) Preparation of dispersion: 1 g of sodium hexametaphosphate was weighed and added to 15 g of deionized water, and stirred at a stirring speed of 500 r / min until it was completely dissolved to form a dispersion;

[0040] (ii) Premixing: Add 40g pure acrylic emulsion and 0.5g silicone defoamer into the dispersion and stir at a stirring speed of 800r / min for 10 minutes to preliminarily mix the ingredients;

[0041] (III) Mixing and filling: slowly add 30g of modified silica powder, 15g of hollow glass microspheres and 12g of rutile titanium dioxide into the above mixed solution, increase the stirring speed to 1200r / min, and stir for 20 minutes to fully disperse the solid particles in the mixed solution;

[0042] (iv) Thickening adjustment: add 1.2 g of hydroxyethyl cellulose, continue stirring for 10 minutes, and then use the remaining 15 g of deionized water to adjust the viscosity of the coating to an appropriate range (measured by a Tu-4 viscometer as 100 s).

[0043] Performance test data

[0044]

[0045]

[0046] As can be seen from the above table, the particle size of the modified silicon micropowder obtained by the two implementation methods is within a small range (about 3-5μm), and the particle size distribution is narrow (D90-D10 is less than 8μm), which shows that the preparation method can effectively control the particle size of silicon micropowder and disperse it more evenly in the coating system, which is conducive to its better performance in subsequent coating applications; the contact angle data shows that the modified silicon micropowder has good hydrophobicity (contact angle of more than 110°), which shows that the modification process has successfully changed the surface properties of silicon micropowder. This hydrophobicity is conducive to its dispersion in the coating system and its combination with organic components, and also helps to improve the water resistance and other related properties of the coating;

[0047] Under simulated solar radiation, the exterior wall thermal insulation coatings prepared by the two implementation methods showed significant thermal insulation effects, and the temperature difference between the inside and outside can reach 16°C and 18°C, respectively. This fully proves the effectiveness of the modified silica powder and coating formula of the present invention in improving thermal insulation performance, and can meet the needs of thermal insulation and energy saving of building exterior walls; after 1000h of QUV accelerated aging test, the color difference and gloss loss rate of the two coatings are controlled at a low level, and the powdering level is low (0-0 level), indicating that the coating has good weather resistance; this means that the coating can maintain a good appearance and performance during long-term use, and reduce aging problems caused by environmental factors such as ultraviolet radiation and temperature changes; the cross-cutting method test shows that the adhesion between the coating and the substrate is level 0, indicating that the coating is firmly bonded to the substrate. At the same time, after being stored at 50°C for 30 days, the coating has no stratification phenomenon and the viscosity change rate is low (less than 10%), which reflects good storage stability; this shows that the coating formula and preparation process of the present invention are excellent in ensuring the stability of coating quality, which is conducive to the long-term storage and practical application of the coating.

[0048] In summary, the modified silica powder and its application in exterior wall thermal insulation coatings involved in the present invention perform well in multiple key performance indicators, verifying the feasibility and advantages of the invention. Although the performances of the various embodiments are slightly different, they can meet the requirements of high-quality exterior wall thermal insulation coatings as a whole.

[0049] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A modified silicon powder, characterized in that: The formula composition by weight is: 90-100 parts of silicon micropowder, 3-5 parts of gamma-methacryloxypropyltrimethoxysilane, 1-2 parts of stearic acid, 2-3 parts of nano titanium dioxide, and 2-4 parts of polyethylene glycol.

2. The modified silicon micropowder according to claim 1, characterized in that: The silicon micropowder has a particle size of 1-10 μm and a purity of ≥99%.

3. A method for preparing modified silicon micropowder, characterized in that: The silicon micropowder is the silicon micropowder described in claim 1 or 2, and the preparation method thereof is as follows: (i) Mixing pretreatment: Add silicon micropowder, stearic acid and polyethylene glycol into a high-speed mixer in proportion, mix at a speed of 800-1000r / min for 15-20 minutes to make the ingredients preliminarily evenly mixed, and control the mixing temperature at 40-50°C. This step can make stearic acid and polyethylene glycol better adhere to the surface of silicon micropowder and improve the subsequent reaction activity; (ii) Modification reaction: transfer the mixture of step (i) to a reaction kettle, add γ-methacryloxypropyltrimethoxysilane and nano-titanium dioxide, stir at a stirring speed of 200-300r / min under nitrogen protection, and heat to 70-80°C for 3-4 hours. Nitrogen protection can prevent the coupling agent and other components from oxidizing at high temperatures, thus ensuring the modification effect; (III) Post-treatment: After the reaction is completed, the mixture is naturally cooled to room temperature, then washed with anhydrous ethanol 2-3 times to remove unreacted substances, and finally vacuum dried at 60-70°C for 2-3 hours to obtain modified silicon micropowder.

4. A modified silicon powder according to any one of claims 1 to 3 and its use in exterior wall thermal insulation coatings, characterized in that: The external wall thermal insulation coating has a formula composition by weight: 20-30 parts of modified silicon micropowder, 30-40 parts of pure acrylic emulsion, 10-15 parts of hollow glass microspheres, 10-12 parts of rutile titanium dioxide, 0.5-1 part of sodium hexametaphosphate, 0.2-0.5 parts of organosilicon defoamer, 0.8-1.2 parts of hydroxyethyl cellulose, and 20-30 parts of deionized water.

5. A modified silicon powder according to claim 4 and its use in exterior wall thermal insulation coating, characterized in that: The preparation method of the exterior wall thermal insulation coating comprises the following steps: (i) Preparation of dispersion: adding sodium hexametaphosphate to a portion of deionized water, stirring at a stirring speed of 400-500 r / min until completely dissolved to form a dispersion; (ii) Premixing: Add pure acrylic emulsion and silicone defoamer to the dispersion and stir at a stirring speed of 600-800 r / min for 10-15 minutes to preliminarily mix the ingredients; (III) Mixing and filling: slowly add modified silica powder, hollow glass microspheres and rutile titanium dioxide into the above-mentioned mixed solution, increase the stirring speed to 1000-1200 r / min, and stir for 20-30 minutes to fully disperse the solid particles in the mixed solution; (iv) Thickening adjustment: Add hydroxyethyl cellulose and continue stirring for 10-15 minutes, then use the remaining deionized water to adjust the viscosity of the coating to an appropriate range (80-100s measured by a Tu-4 viscometer).

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