Natural stone powder modification preparation method of exterior wall stone-like coating

Abstract

The invention discloses a natural stone powder modification preparation method of an exterior wall stone-like coating, relates to the technical field of exterior wall coating preparation, and comprises a natural stone powder modification method, and natural stone powder modification raw materials comprise natural stone powder, nano titanium dioxide, a biological enzyme, a binder, a dispersant, a weather-resistant agent, a defoaming agent and a thickening agent. The preparation method comprises the steps of natural stone powder pretreatment, nano titanium dioxide surface treatment, biological enzyme catalytic modification, coating raw material mixing and quality detection and adjustment, and has the advantages that through nano titanium dioxide surface treatment and biological enzyme catalytic modification, the surface property of the natural stone powder is changed, so that the natural stone powder is combined with a binder more tightly, and the quality of the coating is improved; meanwhile, the adhesive agent compounded by silica sol and water-borne epoxy resin is selected, so that the adhesive force between the coating and a wall body is further enhanced, the problem that the coating is easy to fall off is effectively solved, and the service life of the outer wall stone-like coating is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of exterior wall coating preparation, in particular to a natural stone powder modified preparation method for exterior wall imitation stone coating. Background Art

[0002] With the rapid development of the construction industry, exterior imitation stone coatings have been widely used in the field of building exterior walls due to their unique decorative effects and protective properties. Natural stone powder, as an important raw material for exterior imitation stone coatings, provides the coating with a real stone appearance due to its natural mineral composition and unique texture. The raw materials of natural stone powder are widely sourced. Minerals such as marble and quartz stone are abundant and widely distributed, which provides a solid resource base for large-scale production. Compared with some rare or synthetic building materials, natural stone powder is cheaper and has obvious advantages in construction cost control. Especially in large-scale construction projects, the use of natural stone powder can effectively reduce material procurement costs and improve project economic benefits. The existing natural stone powder modification preparation method has certain limitations. In terms of process complexity, the traditional preparation process often requires multiple tedious steps, such as multiple grinding, complex chemical treatment, etc., which is not only time-consuming and energy-consuming, but also increases production costs. From the perspective of production efficiency, the tedious process leads to a long production cycle, which is difficult to meet the growing market demand. To this end, we propose a natural stone powder modification preparation method for exterior wall imitation stone coatings. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing modified natural stone powder for exterior wall imitation stone coating.

[0004] To achieve the above objectives, the present invention provides the following technical solutions: a method for preparing a natural stone powder modified exterior wall imitation stone coating, comprising a natural stone powder modification method, wherein the raw materials for modifying the natural stone powder include natural stone powder, nano-titanium dioxide, biological enzymes, a binder, a dispersant, a weathering agent, a defoaming agent, and a thickener, and the preparation steps include natural stone powder pretreatment, nano-titanium dioxide surface treatment, biological enzyme catalytic modification, coating raw material mixing, and quality inspection and adjustment. The specific operating steps of the natural stone powder modification preparation method are as follows: Step 1: Mix dolomite powder and kaolin powder to make mixed stone powder for later use, screen and wash it, and then dry it; Step 2: Surface-treating the nano-titanium dioxide, and then adding dried natural stone powder to mix the surface to obtain treated stone powder; Step 3: prepare a biological enzyme solution, add the treated stone powder into the biological enzyme solution, and obtain modified natural stone powder after enzyme catalysis treatment for standby use; Step four, the modified natural stone powder, binder, dispersant, weather resistant agent, defoaming agent and thickening agent are added into a high-speed dispersion machine according to the proportion, and stirred and mixed to prepare stone-like slurry products; Step five, the stone-like slurry products are detected in performance, including stone powder dispersion degree, viscosity, adhesion, weather resistance and water resistance, the stone-like slurry products are adjusted according to the detection results, and the products are sealed and packaged after detection.

[0005] As a further scheme of the application, the binder is silica sol and water-based epoxy resin, the dispersant is a graft copolymer dispersant based on polyether amine and maleic anhydride, the weather resistant agent is a composite weather resistant agent, the defoaming agent is a polyether modified silicone defoaming agent, and the thickening agent is a hydrophobically modified hydroxyethyl cellulose.

[0006] As a further scheme of the application, in step one, the dolomite powder and kaolin powder are mixed and then screened and classified by using a multi-layer vibrating screen, the mixed stone powder is sequentially passed through vibrating screens with 100 meshes, 200 meshes and 300 meshes, the vibration frequency is set to 50Hz-60Hz, and the amplitude is set to 3mm-5mm, the screened stone powder is placed into an ultrasonic cleaning machine, deionized water and sodium dodecyl sulfate with a mass fraction of 0.5%-1% are added, the power of the ultrasonic cleaning machine is set to 300W-500W, the frequency is set to 40kHz-60kHz, and the cleaning time is set to 20min-30min, after cleaning, the stone powder is transferred to a centrifuge for centrifugal separation, the rotation speed of the centrifuge is set to 3000r / min-4000r / min, and the centrifugal time is set to 10min-15min, the mixed stone powder is separated from the cleaning liquid, after separation, the supernatant is poured out, and the precipitate is washed with deionized water, after precipitation, centrifugal separation is performed, and the washing liquid is washed until the pH value is between 6.5-7.5, so that the impurities on the surface of the stone powder are completely removed.

[0007] As a further scheme of the application, in step one, the cleaned mixed stone powder is placed in a vacuum drying box for drying, the vacuum degree of the vacuum drying box is set to 0.08MPa-0.09MPa, the temperature is set to 50℃-70℃, and the drying time is set to 5h-8h, during the drying process, the mixed stone powder is turned over every 1h-2h, the water content of the stone powder is reduced to below 0.3%, and the mixed stone powder is sealed and stored for later use after drying.

[0008] As a further embodiment of the present invention: in the step 2, anhydrous ethanol and deionized water are added in a volume ratio of 3:1 to a three-necked flask equipped with a stirrer, a thermometer and a dropping funnel, the stirring speed is set to 200 r / min-300 r / min, and tetrabutyl titanate is slowly added dropwise to the mixed solution at a dropping rate of 3-5 drops per minute. At the same time, glacial acetic acid accounting for 5%-10% of the mass of tetrabutyl titanate is added. After the addition is completed, the reaction is continued with stirring for 2h-3h. During the reaction, the temperature is controlled at 30°C-40°C to prepare a stable nano-titanium dioxide sol, and its particle size is controlled between 20nm-50nm.

[0009] As a further solution of the present invention: in the step 2, the dried mixed stone powder is added to the nano-titanium dioxide sol, the mass ratio of the mixed stone powder to the nano-titanium dioxide sol is 1:2-3, and the reaction is carried out at a temperature of 50°C-60°C with an agitator at a speed of 200r / min-300r / min for 3h-4h, so that the nano-titanium dioxide is evenly coated on the surface of the stone powder. After the reaction is completed, the mixture is transferred to a centrifuge and centrifuged at a speed of 4000r / min-5000r / min for 15min-20min. After the separation is completed, the supernatant is poured out, and the precipitate is washed with anhydrous ethanol for 4-5 times. After the washing is completed, it is centrifuged, and the precipitate after centrifugation is placed in a vacuum drying oven and dried for 3h-4h at a temperature of 40°C-50°C and a vacuum degree of 0.08MPa-0.09MPa to obtain treated stone powder.

[0010] As a further solution of the present invention: in the step 3, the lipase is dissolved in a phosphate buffer solution with a pH value of 7-8 to prepare an enzyme solution with a concentration of 0.5g / L-1g / L. During the preparation process, the pH value is stabilized between 7-8, and the prepared enzyme solution is placed in a refrigerator at 4°C for storage. The treated stone powder is added to the enzyme solution, and polyethylene glycol acrylate is added at the same time. The mass ratio of the treated stone powder to the monomer is 1:0.5-1. At a temperature of 30°C-40°C, a stirrer is used to stir at 150r / min-200r / min stirring reaction for 8h-12h, after the reaction is completed, the mixed stone powder is transferred to a centrifuge, centrifuged at a speed of 3000r / min-4000r / min for 10min-15min, after the separation is completed, the supernatant is poured out, and the precipitate is rinsed with deionized water, the precipitate is centrifuged and placed in a vacuum drying oven, and dried at a temperature of 40℃-50℃ and a vacuum degree of 0.08MPa-0.09MPa for 3h-4h to obtain the modified natural stone powder for use.

[0011] As a further solution of the present invention: in the step four, the modified natural stone powder accounts for 30%-40%, the binder accounts for 40%-50%, the solvent accounts for 15%-25%, and the total proportion of the dispersant, defoamer, thickener and weathering agent is 3%-8%. The modified natural stone powder with the completed proportion and the solvent accounting for 60%-70% of the total amount are added to the high-speed disperser, and the speed of the disperser is set to 1500r / min-2000r / min, and the dispersion time is 20min-30min. After the dispersion is completed, the binder is added and continuously dispersed for 15min-20min. The modified natural stone powder is evenly dispersed in the binder, and the dispersant, defoamer, thickener, weathering agent and the remaining solvent are added in sequence. The speed of the high-speed disperser is reduced to 1000r / min-1200r / min, stirred for 15min-20min, and the imitation stone slurry product is obtained after stirring evenly.

[0012] As a further solution of the present invention: in the step 5, the performance of the prepared imitation stone slurry product is tested, and the dispersed particle size of the stone powder is detected by a laser particle size analyzer, and the average particle size is required to be between 80nm and 100nm. The viscosity is measured by a rotational viscometer, and the viscosity needs to be controlled between 90KU and 130KU. The adhesion is tested by the pull-off method, and the adhesion tester is used to evenly apply the imitation stone slurry product on a standard test board. After curing, the test is performed, and the adhesion strength needs to be between 2.5MPa and 5MPa. A xenon lamp aging test chamber is used for weather resistance testing, and the light intensity of the test chamber is set to 550W / m²-650W / m², the temperature is controlled at 60℃-70℃, and the relative humidity is 50%-60%. After 1500h of illumination, the color change of the coating is measured using a colorimeter. , requires 1≤ ≤3, conduct an immersion test on the finished imitation stone slurry product in a water resistance test chamber. Completely immerse the test panel coated with the finished imitation stone slurry product in water with the water temperature controlled at 23±2℃ for 96 hours, and observe the blistering, shedding and discoloration of the coating.

[0013] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are: 1. The present invention changes the surface properties of natural stone powder through nano-titanium dioxide surface treatment and bio-enzyme catalytic modification, making it more tightly bonded to the binder. At the same time, the binder compounded with silica sol and water-based epoxy resin is selected to further enhance the adhesion between the coating and the wall, effectively solving the problem of easy peeling of the coating and extending the service life of the exterior wall imitation stone coating. The polyether-modified silicone defoamer can effectively eliminate bubbles generated during the coating preparation process and ensure the uniformity of the coating. The hydrophobically modified hydroxyethyl cellulose thickener can accurately adjust the viscosity of the coating, giving the coating good construction performance and ensuring that the ideal coating effect can be achieved under different construction conditions. 2. The present invention uses the photocatalytic properties of nano-titanium dioxide and the synergistic effect of the composite weathering agent to enable the coating to effectively resist natural erosion such as ultraviolet rays and acid rain, reduce color fading and material powdering, and better maintain the integrity and aesthetics of the coating under long-term exposure to the natural environment, thereby reducing building maintenance costs. The use of a graft copolymer dispersant based on polyetheramine and maleic anhydride significantly improves the dispersibility of natural stone powder in the coating, making the coating texture more delicate and more uniform, thereby enhancing the decorative effect and overall quality of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The following is a flow chart for preparing the exterior stone-like coating in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0016] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0017] Please see the attached Figure 1 The present invention provides a method for preparing a natural stone powder modified exterior wall imitation stone coating, including a natural stone powder modification method. The raw materials for natural stone powder modification include natural stone powder, nano-titanium dioxide, biological enzymes, a binder, a dispersant, a weathering agent, a defoaming agent, and a thickener. The preparation steps include natural stone powder pretreatment, nano-titanium dioxide surface treatment, biological enzyme catalytic modification, coating raw material mixing, and quality inspection and adjustment. The specific operating steps of the natural stone powder modification preparation method are as follows: Step 1: Mix dolomite powder and kaolin powder to make mixed stone powder for later use, screen and wash it, and then dry it; Step 2: Surface-treating the nano-titanium dioxide, and then adding dried natural stone powder to mix the surface to obtain treated stone powder; Step 3: prepare a biological enzyme solution, add the treated stone powder into the biological enzyme solution, and obtain modified natural stone powder after enzyme catalysis treatment for standby use; Step 4: Add the modified natural stone powder, binder, dispersant, weathering agent, defoamer and thickener into a high-speed disperser according to the proportion, and stir and mix to form a finished imitation stone slurry; Step 5: Test the performance of the finished imitation stone slurry, including stone powder dispersion strength, viscosity, adhesion, weather resistance and water resistance. Make targeted adjustments to the finished imitation stone slurry according to the test results. After passing the test, seal and package it for use.

[0018] In one embodiment of the present invention: the binder is silica sol and water-based epoxy resin, the dispersant is a graft copolymer dispersant based on polyetheramine and maleic anhydride, the weathering agent is a composite weathering agent, the defoaming agent is a polyether-modified silicone defoaming agent, and the thickener is hydrophobically modified hydroxyethyl cellulose.

[0019] In one embodiment of the present invention: in step 1, dolomite powder and kaolin powder are mixed and then screened and graded using a multi-layer vibrating screen, the mixed stone powder is sequentially passed through 100 mesh, 200 mesh and 300 mesh vibrating screens, the vibration frequency is set to 50Hz-60Hz, the amplitude is 3mm-5mm, the screened stone powder is placed in an ultrasonic cleaning machine, deionized water and 0.5%-1% mass fraction of sodium lauryl sulfate are added, the power of the ultrasonic cleaning machine is set to 300W-500W, the frequency is set to 40kHz-60kHz, and the cleaning time is 20min-30min. After cleaning, the stone powder is transferred to a centrifuge for centrifugal separation, the speed of the centrifuge is set to 3000r / min-4000r / min, the centrifugation time is 10min-15min, the mixed stone powder is separated from the cleaning liquid, and after separation, the supernatant is poured out, and the precipitate is washed with deionized water. After precipitation, centrifugation is performed and washed until the pH value of the cleaning liquid is between 6.5-7.5 to ensure that impurities on the surface of the stone powder are completely removed.

[0020] In one embodiment of the present invention: in step one, the cleaned mixed stone powder is placed in a vacuum drying oven for drying, the vacuum degree of the vacuum drying oven is set to 0.08MPa-0.09MPa, the temperature is 50℃-70℃, and the drying time is 5h-8h. During the drying process, the mixed stone powder is turned over every 1h-2h to reduce the moisture content of the stone powder to below 0.3%. After drying is completed, the mixed stone powder is sealed and stored for standby use.

[0021] In one embodiment of the present invention: in step 2, anhydrous ethanol and deionized water in a volume ratio of 3:1 are added to a three-necked flask equipped with a stirrer, a thermometer and a dropping funnel, the stirring speed is set to 200 r / min-300 r / min, tetrabutyl titanate is slowly added dropwise to the mixed solution, the dropping speed is set to 3-5 drops per minute, and glacial acetic acid accounting for 5%-10% of the mass of tetrabutyl titanate is added at the same time. After the addition is completed, the stirring reaction is continued for 2h-3h. During the reaction process, the temperature is controlled at 30°C-40°C to prepare a stable nano-titanium dioxide sol, and its particle size is controlled between 20nm-50nm.

[0022] In one embodiment of the present invention: in step 2, the dried mixed stone powder is added to the nano-titanium dioxide sol, the mass ratio of the mixed stone powder to the nano-titanium dioxide sol is 1:2-3, and the reaction is carried out at a temperature of 50°C-60°C using an agitator at a speed of 200r / min-300r / min for 3h-4h, so that the nano-titanium dioxide is evenly coated on the surface of the stone powder. After the reaction is completed, the mixture is transferred to a centrifuge and centrifuged at a speed of 4000r / min-5000r / min for 15min-20min. After separation, the supernatant is poured out, and the precipitate is washed with anhydrous ethanol 4-5 times. After washing, it is centrifuged, and the precipitate after centrifugation is placed in a vacuum drying oven and dried for 3h-4h at a temperature of 40°C-50°C and a vacuum degree of 0.08MPa-0.09MPa to obtain treated stone powder.

[0023] In one embodiment of the present invention: in step 3, lipase is dissolved in a phosphate buffer solution with a pH value of 7-8 to prepare an enzyme solution with a concentration of 0.5g / L-1g / L. During the preparation process, the pH value is stabilized between 7-8, and the prepared enzyme solution is placed in a refrigerator at 4°C for storage. The treated stone powder is added to the enzyme solution, and polyethylene glycol acrylate is added at the same time. The mass ratio of the treated stone powder to the monomer is 1:0.5-1. At a temperature of 30°C-40°C, a stirrer is used at 150r / min-200r / min stirring reaction for 8h-12h, after the reaction is completed, the mixed stone powder is transferred to a centrifuge, centrifuged at a speed of 3000r / min-4000r / min for 10min-15min, after the separation is completed, the supernatant is poured out, and the precipitate is rinsed with deionized water, the precipitate is centrifuged and placed in a vacuum drying oven, and dried at a temperature of 40℃-50℃ and a vacuum degree of 0.08MPa-0.09MPa for 3h-4h to obtain the modified natural stone powder for use.

[0024] In one embodiment of the present invention: in step four, the modified natural stone powder accounts for 30%-40%, the binder accounts for 40%-50%, the solvent accounts for 15%-25%, and the total proportion of the dispersant, defoamer, thickener and weathering agent is 3%-8%. The modified natural stone powder with the completed proportion and the solvent accounting for 60%-70% of the total amount are added to a high-speed disperser, and the speed of the disperser is set to 1500r / min-2000r / min, and the dispersion time is 20min-30min. After the dispersion is completed, the binder is added and continuously dispersed for 15min-20min. The modified natural stone powder is evenly dispersed in the binder, and the dispersant, defoamer, thickener, weathering agent and the remaining solvent are added in sequence. The speed of the high-speed disperser is reduced to 1000r / min-1200r / min, stirred for 15min-20min, and the imitation stone slurry product is obtained after stirring evenly.

[0025] In one embodiment of the present invention: in step five, the performance of the prepared imitation stone slurry product is tested, and the dispersed particle size of the stone powder is detected by a laser particle size analyzer, and the average particle size is required to be between 80nm and 100nm. The viscosity is measured using a rotational viscometer, and the viscosity needs to be controlled between 90KU and 130KU. The adhesion is tested using a pull-off method, and the adhesion tester is used to evenly apply the imitation stone slurry product on a standard test board. After curing, the test is performed, and the adhesion strength needs to be between 2.5MPa and 5MPa. A xenon lamp aging test chamber is used for weather resistance testing, and the light intensity of the test chamber is set to 550W / m²-650W / m², the temperature is controlled at 60℃-70℃, and the relative humidity is 50%-60%. After 1500h of illumination, a colorimeter is used to measure the color change of the coating. , requires 1≤ ≤3, conduct an immersion test on the finished imitation stone slurry product in a water resistance test chamber. Completely immerse the test panel coated with the finished imitation stone slurry product in water with the water temperature controlled at 23±2℃ for 96 hours, and observe the blistering, shedding and discoloration of the coating.

[0026] In one embodiment of the present invention: in step 2, glacial acetic acid is used as a hydrolysis inhibitor to control the particle size of the sol.

[0027] In one embodiment of the present invention, the preparation method of the binder is as follows: Accurately weigh silica sol and water-based epoxy resin in a mass ratio of 3:2, slowly pour the silica sol into a stirring container, turn on the stirring device and stir at a speed of 150r / min-200r / min. During the stirring process, add the water-based epoxy resin dropwise to the silica sol at a uniform speed, and control the addition time to be 15min-20min. After the addition is completed, continue stirring for 30min-40min to prepare the adhesive. During the stirring process, the temperature is maintained at 25℃-35℃ to avoid excessively high or low temperature affecting the performance of the adhesive; The preparation method of the dispersant is as follows: Toluene is added as a solvent to a three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser. The mixture is stirred and heated to 80°C-90°C. A polyetheramine is added to the three-necked flask and stirred to completely dissolve it in the toluene. Maleic anhydride in an amount of 1%-2% by weight of the polyetheramine is weighed and slowly added to the three-necked flask. Azobisisobutyronitrile in an amount of 0.5%-1% by weight of the total weight of the polyetheramine and maleic anhydride is also added as an initiator. The reaction temperature is maintained at 80°C-90°C and the reaction is carried out for 3-4 hours with continuous stirring. After the reaction is completed, the reaction solution is cooled to room temperature and the toluene solvent is removed by vacuum distillation to prepare a graft copolymer dispersant based on polyetheramine and maleic anhydride. The preparation method of the weathering agent is as follows: Nano zinc oxide accounts for 40%-60% of the mass of the composite weathering agent, hindered amine light stabilizer accounts for 30%-40%, and antioxidant accounts for 10%-20%. Nano zinc oxide, hindered amine light stabilizer and antioxidant are accurately weighed according to the above ratios, nano zinc oxide is added into a high-speed stirrer, and stirred at a speed of 800r / min-1000r / min. Under stirring, hindered amine light stabilizer and antioxidant are added in sequence, and stirring is continued for 20min-30min. The three ingredients are fully mixed to prepare a composite weathering agent. The defoamer is Dow Defoamer AFE-3168. During the coating preparation process, the defoamer is accurately measured at a ratio of 0.2%-0.5% of the total coating amount. During the coating mixing and stirring process, if a large number of bubbles appear in the coating system, slowly add the defoamer and continue stirring for 5-10 minutes to evenly disperse the defoamer in the coating to exert its defoaming effect. The thickener is "Lotte HECELLOSE® HM10000 hydrophobically modified hydroxyethyl cellulose". When preparing the paint, it is accurately weighed at a dosage of 0.3%-0.6%. In the later stage of mixing and stirring the paint, the hydrophobically modified hydroxyethyl cellulose is slowly added to the paint system. At the same time, stirring is carried out at a speed of 300r / min-500r / min for 30min-40min to fully dissolve the thickener and evenly disperse it in the paint, thereby adjusting the viscosity of the paint and ensuring good construction performance.

[0028] In one embodiment of the present invention: in step three, during the reaction process, lipase catalyzes the graft polymerization of biopolymer monomers on the surface of the stone powder to form a polymer coating layer with hydrophilicity and adhesion.

[0029] In one embodiment of the present invention: in step five, the coating is adjusted in a targeted manner according to the performance test results. If the stone powder dispersion particle size does not meet the requirements, the amount of dispersant is increased, and the amount of each increase is 0.1%-0.2% of the mass of the natural stone powder, and then the dispersion is re-stirred and dispersed for 10min-15min, or the dispersion time is extended by 5min-10min each time, until the stone powder dispersion particle size meets the requirements. When the viscosity is not appropriate, if the viscosity is too high, add an appropriate amount of solvent, each addition amount is 0.5%-1% of the total amount of the coating, stir evenly and measure the viscosity again. If the viscosity is too low, add a thickener, each addition amount is 0.1%-0.2% of the total amount of the coating, stir for 30min-40min and then measure the viscosity again. When the adhesion is insufficient, optimize the bio-enzyme catalytic modification process and adjust the concentration of the enzyme solution.

[0030] Example 50 kg of dolomite powder and 25 kg of kaolin powder were put into a horizontal mixer, the equipment was started and the stirring speed was set to 200 r / min, and the stirring was continued for 30 min to ensure that the two stone powders were fully mixed to make mixed stone powder. Subsequently, a three-layer vibrating screen was used to screen and grade the mixed stone powder. The vibration frequency of the vibrating screen was set to 55 Hz, and the amplitude was adjusted to 4 mm. The mixed stone powder passed through 100 mesh, 200 mesh and 300 mesh sieves in turn, and finally the fine powder passing through the 300 mesh sieve was collected for use. The screened stone powder was transferred to an ultrasonic cleaning machine, 800 L of deionized water and 4 kg of sodium lauryl sulfate with a mass fraction of 0.5% were added, the ultrasonic cleaning machine was turned on, the power was set to 400 W, the frequency was set to 50 kHz, and the cleaning time was 25 min. After the cleaning was completed, the mixture was transferred to The centrifuge was used for centrifugal separation, the speed of the centrifuge was set to 3500r / min, and the centrifugation time was 12min. After the separation was completed, the supernatant was carefully poured out and the precipitate was retained. Then, deionized water was added to the precipitate for washing again, and the centrifugal separation operation was repeated until the pH value of the cleaning solution reached 7 to ensure that the impurities on the surface of the stone powder were completely removed. The cleaned stone powder was placed in a vacuum drying oven for drying. The vacuum degree of the vacuum drying oven was set to 0.085MPa, the temperature was set to 60℃, and the drying time was set to 6h. During the drying process, the stone powder was turned over every 1.5h using a special tool to ensure uniform drying effect. After the drying was completed, the stone powder was taken out and its moisture content was tested. The result showed that the moisture content was 0.25%, which met the requirement of less than 0.3%. The dried stone powder was sealed and stored to prevent moisture absorption. In a 500L three-necked flask equipped with a stirrer, a thermometer and a dropping funnel, 300L of anhydrous ethanol and 100L of deionized water were added, the stirrer was started, the stirring speed was set to 250r / min, and 20kg of tetrabutyl titanate was slowly added dropwise through the dropping funnel at a rate of 4 drops per minute. At the same time, 1.6kg of glacial acetic acid was added to the flask in an amount of 8% by mass of tetrabutyl titanate. After the addition was complete, the stirring state was maintained and the reaction temperature was controlled at 35°C. The stirring reaction was continued for 2.5h to finally obtain a stable nano-titanium dioxide sol with a particle size between 30nm and 40nm. 20kg of dried mixed stone powder was added to the prepared nano-titanium dioxide sol. The mass ratio of the mixed stone powder to the nano-titanium dioxide sol was 1:2.5. The temperature of the reaction system was raised to 55°C, and the stirrer speed was maintained at 250 r / min. The stirring reaction was continued for 3.5 hours to uniformly coat the nano-titanium dioxide on the surface of the stone powder. After the reaction was completed, the mixture was transferred to a centrifuge for centrifugal separation. The centrifuge speed was set to 4500 r / min and the centrifugation time was 18 minutes. After the separation was completed, the supernatant was poured out, the precipitate was collected, and the precipitate was washed with anhydrous ethanol. The washing was repeated 4 times, and centrifugation was performed after each washing. Finally, the washed precipitate was placed in a vacuum drying oven and dried for 3.5 hours at a temperature of 45°C and a vacuum degree of 0.085 MPa to obtain the treated stone powder. Prepare a 10L container, add an appropriate amount of phosphate buffer solution with a pH value of 7.5, slowly add 8g of lipase to the buffer solution, and stir at the same time to ensure that the lipase is completely dissolved to prepare an enzyme solution with a concentration of 0.8g / L. After the preparation is completed, the enzyme solution is placed in a refrigerator at 4°C for refrigeration to maintain the activity of the enzyme. Take out the enzyme solution from the refrigerator, restore it to room temperature, add 10kg of treated stone powder to the enzyme solution, and at the same time, add 5kg of polyethylene glycol acrylate to the reaction system. The treated stone powder and polyethylene glycol acrylate are mixed. The mass ratio was 1:0.5, the reaction temperature was controlled at 35 ° C, and the stirrer was used to stir the reaction at a speed of 180 r / min. The reaction lasted for 10 hours. After the reaction was completed, the mixed stone powder was transferred to a centrifuge for centrifugal separation. The centrifuge speed was set to 3800 r / min and the centrifugal time was 12 minutes. After the separation was completed, the supernatant was poured out, the precipitate was collected, and the precipitate was rinsed with deionized water and then centrifuged again. The precipitate after centrifugation was placed in a vacuum drying oven and dried at a temperature of 45 ° C and a vacuum degree of 0.085 MPa. After drying for 3.5 hours, the modified natural stone powder was prepared for standby use. The ingredients were prepared according to the mass fraction, with the modified natural stone powder accounting for 35%, the binder accounting for 45%, the solvent accounting for 15%, and the total additive accounting for 5%. Among them, the binder was made by mixing silica sol and water-based epoxy resin in a ratio of 3:1. The additives included 2% of polyetheramine-maleic anhydride graft copolymer dispersant, 1% of polyether modified silicone defoamer, 1% of hydrophobically modified hydroxyethyl cellulose thickener and 1% of composite weathering agent. First, the modified natural stone powder and 60% of the total solvent were added to the high-speed disperser and started. Disperser, set the speed to 1800r / min, the dispersing time to 25min, so that the modified stone powder is fully dispersed in the solvent. Then, add binder to the disperser and continue to disperse at a speed of 1800r / min for 18min to ensure that the modified natural stone powder is evenly dispersed in the binder. After that, add dispersant, defoaming agent, thickener, weathering agent and the remaining 40% solvent to the disperser in turn, reduce the speed of the high-speed disperser to 1100r / min, and continue stirring for 18min to ensure that all raw materials are fully mixed to obtain the finished stone-like slurry.

[0031] Comparative Example 1 40 kg of dolomite powder and 20 kg of kaolin powder were mixed and screened using a 150-mesh single-layer vibrating screen. The vibration frequency was set to 50 Hz and the amplitude was adjusted to 3 mm to remove large particles of impurities. The screened stone powder was placed in a common cleaning tank, 500 L of deionized water and 3 kg of 0.5% detergent were added, and the mixture was washed at a stirring speed of 150 r / min for 15 minutes. After washing, the mixture was filtered using a common filter device, and the stone powder was allowed to drain naturally. The mixture was then placed in an oven and dried at 80 ° C for 4 hours to reduce the moisture content of the stone powder to about 1%. The mixture was then sealed and stored. A nano-titanium dioxide solution was prepared in a beaker by directly adding 1 kg of nano-titanium dioxide powder to 5 L of deionized water and stirring at 200 r / min for 10 minutes to form a simply dispersed nano-titanium dioxide solution. 25 kg of dried stone powder was added to the solution at a mass ratio of stone powder to nano-titanium dioxide solution of approximately 1:0.2. The mixture was stirred for 30 minutes and then dried in a 60°C oven for 3 hours to obtain the surface-treated stone powder. This process did not precisely control the nano-titanium dioxide particle size, nor did it follow strict sol preparation and coating procedures. Traditional acrylic emulsion is used as a binder. In the coating formula, modified natural stone powder accounts for 30%, acrylic emulsion binder accounts for 45%, and a solvent of xylene and butyl acetate mixed in a ratio of 1:1 accounts for 20%. A commercially available general-purpose dispersant is used, and the dosage is 1% of the mass of the stone powder. The dosage of ordinary defoaming agent is 0.3% of the total amount of the coating, and the addition amount of ordinary thickener is 0.4%. No composite weathering agent is used, and only a small amount of ultraviolet absorber is added, and its dosage accounts for 0.5% of the total amount of the coating. The measured modified natural stone powder and 60% of the mass of the solvent are added to a stirring kettle, and stirred at a stirring speed of 800r / min for 15 minutes. After adding the acrylic emulsion, stirring is continued for 20 minutes. Then, the dispersant, defoaming agent, thickener, ultraviolet absorber and the remaining solvent are added in turn, and the stirring speed is reduced to 600r / min and stirred for another 15 minutes to obtain a stone-like slurry.

[0032] Comparative Example 2 50 kg of calcite powder was selected as the natural stone powder raw material, and was screened using a 200-mesh vibrating sieve. The vibration frequency was set to 55 Hz and the amplitude was adjusted to 4 mm. The screened stone powder was placed in an ultrasonic cleaning machine, 600 L of deionized water and 4 kg of 0.8% sodium dodecylbenzene sulfonate were added, the cleaning machine power was set to 400 W, the frequency was adjusted to 50 kHz, and the cleaning was performed for 20 min. After cleaning, the powder was centrifuged, the centrifuge speed was set to 3000 r / min, the centrifugation time was 10 min, the supernatant was poured out, and the precipitate was washed with deionized water until the pH value of the cleaning solution reached 7.0. The cleaned stone powder was placed in a vacuum drying oven, the vacuum degree was set to 0.08 MPa, the temperature was adjusted to 60 ° C, and dried for 6 h. During the drying process, the powder was turned over every 2 h to reduce the moisture content of the stone powder to 0.4%, and then sealed and stored. 200L of anhydrous ethanol and 80L of deionized water were added to a three-necked flask, stirring was started, the stirring speed was set to 250r / min, 15kg of ethyl titanate was slowly added dropwise, the dropping speed was controlled to 3 drops per minute, and formic acid accounting for 6% of the mass of ethyl titanate was added at the same time. After the addition was completed, the reaction was stirred at a temperature of 35°C for 2h to prepare a nano-titanium dioxide sol, 20kg of dried calcite powder was added to the sol, the mass ratio of stone powder to sol was 1:2.2, and the reaction was stirred at a temperature of 55°C and a stirring speed of 250r / min for 3h. After the reaction was completed, centrifugation was performed, the centrifuge speed was set to 4000r / min, the centrifugation time was 15min, the precipitate was washed 3 times with anhydrous ethanol, and centrifugation was performed after each washing. Finally, the precipitate was placed in a vacuum drying oven, the temperature was set to 45°C, the vacuum degree was set to 0.08MPa, and dried for 3h to obtain the treated stone powder; Styrene acrylic emulsion is used as a binder. In the coating formula, modified natural stone powder accounts for 35%, styrene acrylic emulsion binder accounts for 42%, and a solvent mixture of propylene glycol methyl ether and water in a ratio of 3:2 accounts for 20%. A dispersant based on polyethylene imine and acrylic acid is used, and the amount used is 1.5% of the mass of the stone powder. The amount of polyether modified silicone defoamer is 0.4% of the total coating amount. Hydrophobically modified carboxymethyl cellulose is used, and the addition amount is 0.5%. The weathering agent is simply mixed with nano-silica and hindered amine light stabilizer. The modified natural stone powder and 65% of the solvent are added to a high-speed disperser, the speed is adjusted to 1500r / min, and the dispersion is carried out for 20 minutes. After adding the styrene acrylic emulsion, the dispersion is continued for 15 minutes. Then the dispersant, defoamer, thickener, weathering agent and remaining solvent are added in turn, the speed is reduced to 1000r / min, and the mixture is stirred for 15 minutes to obtain a stone-like slurry.

[0033] The performance comparison test of the stone-like slurries prepared in the embodiment and two groups of comparative examples was carried out: Materials: imitation stone slurry prepared in Example, Comparative Example 1 and Comparative Example 2, standard test plate, bonding strength tester, laser particle size analyzer, rotational viscometer, xenon lamp aging test chamber, water resistance test chamber, colorimeter, etc. Equipment: Calibrate according to relevant standards and ensure that the equipment can operate normally to ensure the accuracy of test data; Stone powder dispersion particle size test, Method: Take appropriate amounts of the imitation stone slurries of Example, Comparative Example 1 and Comparative Example 2, respectively, and perform tests according to the operating instructions of the laser particle size analyzer to record the average particle size of the stone powder. This index reflects the degree of uniformity of dispersion of the stone powder in the coating. The smaller the particle size and the narrower the distribution, the better the dispersibility, and the better the texture and stability of the coating. Viscosity test, Method: Use a rotational viscometer, at a constant temperature of 25°C, immerse the rotor in the imitation stone slurry, measure according to the instrument operating procedures, and record the viscosity value (unit: KU). Appropriate viscosity is crucial to the application performance of the paint. Too high or too low viscosity will affect the application effect and quality of the paint. Adhesion test, Method: Use the pull-off method to evenly apply the imitation stone slurry on a standard test panel. Dry and cure according to the specified process and conditions. Then use an adhesion tester to select multiple evenly distributed test points on the test panel to perform an adhesion test and record the adhesion strength (unit: MPa). Strong adhesion means that the paint is tightly bonded to the wall and can effectively prevent the coating from falling off. Weather resistance test, Method: Place the standard test panel coated with imitation stone slurry in a xenon lamp aging test chamber, set the light intensity to 600W / m², the temperature to 65℃, the relative humidity to 55%, and continue the light for 1500 hours. After the test, use a colorimeter to measure the color change of the coating. value, and observe whether there is powdering, cracking, etc. on the coating surface. The smaller the value, the better the weather resistance of the coating, and the better it can maintain color stability and coating integrity in a long-term natural environment; Water resistance test, Method: Immerse the standard test board coated with imitation stone slurry completely in the water of the water resistance test box, control the water temperature at 23±2℃, and soak for 96 hours. After soaking, take out the test board and observe whether the coating has blistering, falling off, discoloration, etc. The coating with good water resistance can effectively resist rain erosion and protect the wall from moisture.

[0034] Test results: Stone powder dispersion particle size, Example: The average particle size is 90 nm and the particle size distribution is uniform, indicating that the modified preparation method of the present invention, including fine screening and classification, nano-titanium dioxide surface treatment and effective dispersant use, enables the stone powder to be highly dispersed in the coating, ensuring the fine texture and stability of the coating; Comparative Example 1: The average particle size is 120 nm, and the particle size distribution is relatively wide. Due to the simplified modification process, the nano-titanium dioxide particle size is not precisely controlled, and the sol preparation and coating process are not strictly followed, resulting in poor dispersion of the stone powder, affecting the appearance and performance of the coating; Comparative Example 2: The average particle size is 110 nm, and the dispersion effect is between the embodiment and comparative example 1. Although similar cleaning, drying and partial surface treatment processes are used, different natural stone powder and some raw materials are used, making the stone powder dispersion performance inferior to the embodiment; Viscosity, Example: Viscosity is 110KU; Comparative Example 1: Viscosity is 80KU; Comparative Example 2: Viscosity is 100KU; Adhesion, Example: Adhesion strength is 3.8MPa; Comparative Example 1: Adhesion strength is 1.8 MPa; Comparative Example 2: Adhesion strength is 2.2 MPa; Weather resistance, Example: After 1500 hours of light exposure, the color changes 2.1, no powdering or cracking on the coating surface; Comparative Example 1: Color Change 4, slight powdering occurs; Comparative Example 2: Color Change It is 3.5, and there are also slight signs of powdering; Water resistance, Example: After 96 hours of immersion, the coating showed no blistering or shedding, and only slight discoloration; Comparative Example 1: Slight bubbling and discoloration occurred; Comparative Example 2: Slight discoloration but no blistering or shedding.

[0035] Through the performance comparison test of the embodiment and two groups of comparative examples of stone-like slurries, it can be seen that the embodiment of the stone-like slurry shows significant advantages in stone powder dispersion particle size, viscosity, adhesion, weather resistance and water resistance, and has good application prospects and practical value.

[0036] Although the present application is disclosed with reference to the preferred embodiments, it is not intended to limit the present application and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the technical solutions of the present application, all fall within the protection scope defined by the claims of the present application.

Claims

1. A method for preparing a natural stone powder modified exterior wall stone-like coating, comprising a natural stone powder modification method, characterized in that: The raw materials for modifying natural stone powder include natural stone powder, nano-titanium dioxide, biological enzymes, binders, dispersants, weathering agents, defoamers, and thickeners. The preparation steps include natural stone powder pretreatment, nano-titanium dioxide surface treatment, biological enzyme catalytic modification, coating raw material mixing, and quality inspection and adjustment. The specific operation steps of the natural stone powder modification preparation method are as follows: Step 1: Mix dolomite powder and kaolin powder to make mixed stone powder for later use, screen and wash it, and then dry it; Step 2: Surface-treating the nano-titanium dioxide, and then adding dried natural stone powder to mix the surface to obtain treated stone powder; Step 3: prepare a biological enzyme solution, add the treated stone powder into the biological enzyme solution, and obtain modified natural stone powder after enzyme catalysis treatment for standby use; Step 4: Add the modified natural stone powder, binder, dispersant, weathering agent, defoamer and thickener into a high-speed disperser according to the proportion, and stir and mix to form a finished imitation stone slurry; Step 5: Test the performance of the finished imitation stone slurry, including stone powder dispersion strength, viscosity, adhesion, weather resistance and water resistance. Make targeted adjustments to the finished imitation stone slurry according to the test results. After passing the test, seal and package it for use.

2. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, wherein: The binder is silica sol and water-based epoxy resin, the dispersant is a graft copolymer dispersant based on polyetheramine and maleic anhydride, the weathering agent is a composite weathering agent, the defoaming agent is a polyether-modified silicone defoaming agent, and the thickener is hydrophobically modified hydroxyethyl cellulose.

3. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, wherein: In the step 1, dolomite powder and kaolin powder are mixed and screened and graded using a multi-layer vibrating screen, the mixed stone powder is sequentially passed through 100-mesh, 200-mesh and 300-mesh vibrating screens, the vibration frequency is set to 50 Hz-60 Hz, the amplitude is 3 mm-5 mm, the screened stone powder is placed in an ultrasonic cleaning machine, deionized water and sodium lauryl sulfate with a mass fraction of 0.5%-1% are added, the power of the ultrasonic cleaning machine is set to 300 W-500 W, the frequency is set to 40 kHz-60 kHz, and the cleaning time is 20 min-30 min. After cleaning, the stone powder is transferred to a centrifuge for centrifugal separation, the speed of the centrifuge is set to 3000 r / min-4000 r / min, the centrifugation time is 10 min-15 min, the mixed stone powder is separated from the cleaning solution, the supernatant is poured out after separation, and the precipitate is washed with deionized water. After precipitation, centrifugation is performed and washed until the pH value of the cleaning solution is between 6.5 and 7.5 to remove impurities on the surface of the stone powder.

4. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, characterized in that: In the step 1, the cleaned mixed stone powder is placed in a vacuum drying oven for drying, the vacuum degree of the vacuum drying oven is set to 0.08MPa-0.09MPa, the temperature is 50°C-70°C, and the drying time is 5h-8h. During the drying process, the mixed stone powder is turned over every 1h-2h to reduce the moisture content of the stone powder to below 0.3%. After drying is completed, the mixed stone powder is sealed and stored for later use.

5. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, characterized in that: In the step 2, anhydrous ethanol and deionized water in a volume ratio of 3:1 are added to a three-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, and the stirring speed is set to 200 r / min-300 r / min. Tetrabutyl titanate is slowly added dropwise to the mixed solution at a dropping speed of 3-5 drops per minute. At the same time, glacial acetic acid accounting for 5%-10% of the mass of tetrabutyl titanate is added. After the dropwise addition is completed, the reaction is continued with stirring for 2h-3h. The temperature is controlled at 30°C-40°C during the reaction process to prepare a stable nano-titanium dioxide sol with a particle size between 20nm and 50nm.

6. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, characterized in that: In the step 2, the dried mixed stone powder is added to the nano-titanium dioxide sol, the mass ratio of the mixed stone powder to the nano-titanium dioxide sol is 1:2-3, and the mixture is stirred at a speed of 200 r / min-300 r / min using an agitator for 3 h-4 h at a temperature of 50° C.-60° C. to uniformly coat the nano-titanium dioxide on the surface of the stone powder. After the reaction is completed, the mixture is transferred to a centrifuge and centrifuged at a speed of 4000 r / min-5000 r / min for 15 min-20 min. After the separation is completed, the supernatant is poured out, and the precipitate is washed with anhydrous ethanol for 4-5 times. After the washing is completed, it is centrifuged, and the precipitate after centrifugation is placed in a vacuum drying oven and dried at a temperature of 40° C.-50° C. and a vacuum degree of 0.08 MPa-0.09 MPa for 3 h-4 h to obtain the treated stone powder.

7. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, characterized in that: In the step 3, the lipase is dissolved in a phosphate buffer solution with a pH value of 7-8 to prepare an enzyme solution with a concentration of 0.5g / L-1g / L. During the preparation process, the pH value is stabilized between 7-8, and the prepared enzyme solution is placed in a refrigerator at 4°C for storage. The treated stone powder is added to the enzyme solution, and polyethylene glycol acrylate is added at the same time. The mass ratio of the treated stone powder to the monomer is 1:0.5-1. At a temperature of 30°C-40°C, a stirrer is used to stir the reaction at a speed of 150r / min-200r / min for 8h-12h. During the reaction, polyethylene glycol One end of the polymer chain generated by acrylate polymerization is connected to lipase, and the other end is chemically bonded to the surface active group of the stone powder to form a hydrophilic coating layer on the surface of the stone powder. After the reaction is completed, the mixed stone powder is transferred to a centrifuge and centrifuged at a speed of 3000r / min-4000r / min for 10min-15min. After the separation is completed, the supernatant is poured out and the precipitate is rinsed with deionized water. After the precipitate is centrifuged, it is placed in a vacuum drying oven and dried at a temperature of 40℃-50℃ and a vacuum degree of 0.08MPa-0.09MPa for 3h-4h to obtain the modified natural stone powder for use.

8. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, characterized in that: In the step four, the modified natural stone powder accounts for 30%-40%, the binder accounts for 40%-50%, the solvent accounts for 15%-25%, and the total proportion of the dispersant, defoamer, thickener and weathering agent is 3%-8%. The modified natural stone powder with the completed proportion and the solvent accounting for 60%-70% of the total amount are added to the high-speed disperser, and the speed of the disperser is set to 1500r / min-2000r / min, and the dispersion time is 20min-30min. After the dispersion is completed, the binder is added and continuously dispersed for 15min-20min. The modified natural stone powder is evenly dispersed in the binder, and the dispersant, defoamer, thickener, weathering agent and the remaining solvent are added in sequence. The speed of the high-speed disperser is reduced to 1000r / min-1200r / min, stirred for 15min-20min, and the imitation stone slurry product is obtained after stirring evenly.

9. The method for preparing a natural stone powder modified exterior wall stone-like coating according to claim 1, characterized in that: In the step 5, the performance of the prepared imitation stone slurry product is tested, and the dispersed particle size of the stone powder is detected using a laser particle size analyzer, and the average particle size is required to be between 80nm and 100nm. The viscosity is measured using a rotational viscometer, and the viscosity needs to be controlled between 90KU and 130KU. The adhesion is tested using a pull-off method, and the imitation stone slurry product is evenly applied to a standard test board using an adhesion tester. After curing, the test is performed, and the adhesion strength needs to be between 2.5MPa and 5MPa. A xenon lamp aging test chamber is used for weather resistance testing, and the light intensity of the test chamber is set to 550W / m²-650W / m², the temperature is controlled at 60℃-70℃, and the relative humidity is 50%-60%. After 1500h of illumination, the color change of the coating is measured using a colorimeter. , requiring 1≤ ≤3, conduct an immersion test on the finished imitation stone slurry product in a water resistance test chamber. Completely immerse the test panel coated with the finished imitation stone slurry product in water with the water temperature controlled at 23±2℃ for 96 hours, and observe the blistering, shedding and discoloration of the coating.

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