A heat-insulating coating for the inner wall of a flue-cured tobacco house and a method for preparing the same

Abstract

The present application relates to a kind of curing barn wall thermal insulation coating and its preparation method, with nano silicon powder, nano silicon sol as main raw material, with hexadecyl trimethyl ammonium chloride, carboxyethyl silane triol sodium salt and hexadecyl trimethyl ammonium bromide as dispersing agent, with dimethyl cellulose and polyvinyl alcohol as thickening agent, with modified dimethyl siloxane emulsion as film forming agent, by coating nano SiO2 coating on the inner wall of curing barn, and film forming agent is coated on the outside of coating, form a layer of thermal insulation coating with better thermal insulation effect, stronger hydrophobicity, to improve the thermal insulation effect of curing barn.The present application is simple to operate and process green environmental protection, can realize large-scale industrial production, thermal insulation coating has the characteristics of thermal insulation and hydrophobicity, can long-term service in the curing barn environment with higher temperature and humidity, and can protect curing barn inner wall thermal insulation material, not easy to make it aging damage.

Description

Technical Field

[0001] This invention relates to the field of building insulation coating preparation, and more particularly to an insulation coating for the inner wall of a tobacco curing barn and its preparation method. Background Technology

[0002] Panel-type tobacco curing barns are energy-saving, environmentally friendly, and easy to assemble and disassemble, making them the most widely used type of tobacco curing barn. However, because these barns require frequent disassembly, they are prone to damage and aging over long periods of service. This significantly reduces their insulation performance, leading to insufficient energy utilization and affecting the quality of the cured tobacco, resulting in income losses for tobacco farmers.

[0003] Currently, panel-type tobacco curing barns are mainly composed of a single layer of corrugated steel sheets and a steel frame, with an internal insulation layer approximately 1 cm thick. During long-term disassembly, assembly, and service, the corrugated steel sheets are prone to rust and damage, and the internal insulation is easily torn or deformed and damaged under the high temperature and humidity conditions of tobacco curing. This significantly reduces the insulation performance of the barn, affecting the quality of tobacco curing. However, replacing old tobacco curing barns with new ones faces economic cost pressures and land policy obstacles. Therefore, if an insulation layer could be applied to the inner walls of damaged or old tobacco curing barns, the insulation performance could be improved, the quality of tobacco curing could be improved, and the income and enthusiasm of tobacco farmers could be increased. However, since the curing process in tobacco curing barns is a high-temperature (40℃~80℃) and high-humidity (>90%) environment, a long-life insulation coating that can both retain heat and repel water is needed. Summary of the Invention

[0004] This invention provides a thermal insulation coating for the inner wall of a tobacco curing barn and its preparation method. The invention is simple to operate and the process is green and environmentally friendly, enabling large-scale industrial production. The thermal insulation coating has both thermal insulation and water-repellent properties, and can be used for a long time in the high temperature and humidity environment of a tobacco curing barn, and is not easily aged or damaged.

[0005] To achieve the above objectives, the technical solution adopted by the present invention includes:

[0006] A heat-insulating coating for the inner wall of a tobacco curing barn is prepared by means of nano-silica powder, nano-silica sol, dispersant, thickener and film-forming agent. The viscosity of the nano-silica sol is adjusted to 1.5 mPa·s to 2.0 mPa·s, and the pH of the nano-silica sol is adjusted to 8.1 to 9.5 to obtain a modified nano-silica sol. Then, the nano-silica powder is added to the modified nano-silica sol, and then the dispersant and thickener are added to the modified nano-silica sol in sequence to obtain the heat-insulating coating.

[0007] The insulation coating on the inner wall of the tobacco curing barn consists of an insulation coating layer and a film-forming agent layer.

[0008] Optionally, the particle size of the nano-silicon powder is 5nm to 10nm, and the mass ratio of the nano-silicon powder to the nano-silicon sol is (0.5 to 1): 1.

[0009] Optionally, the dispersant includes hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol, and hexadecyltrimethylammonium bromide in a mass ratio of 1:1:1.

[0010] Optionally, the total mass ratio of the dispersant to the total mass ratio of the modified silica sol and silica powder is 1 / (10-20).

[0011] Optionally, the thickener includes dimethyl cellulose and polyvinyl alcohol in a mass ratio of 1:1.

[0012] Optionally, the total mass ratio of the thickener to the total mass of the modified silica sol and silica powder is 1 / (10-20).

[0013] Optionally, the film-forming agent has a viscosity of 1.9 mPa·s to 3.8 mPa·s and a pH of 2.8 to 3.5.

[0014] Optionally, the preparation of the film-forming agent includes: first stirring polydimethylsiloxane in water until uniform, and then adding an emulsifier to emulsify it into a polydimethylsiloxane emulsion.

[0015] Optionally, both the thermal insulation coating and the film-forming agent require high-speed stirring during the preparation process. The high-speed stirring speed is 2000 r / min to 5000 r / min, and the stirring time is 5 to 10 min.

[0016] The preparation method of the heat-insulating coating on the inner wall of the tobacco curing barn according to any one of the present invention includes: applying the heat-insulating coating to the inner wall surface of the chamber to be insulated to form a heat-insulating coating layer, and then applying a film-forming agent to the outside of the heat-insulating coating layer to form a film-forming agent layer, and curing at room temperature for 3 to 6 hours.

[0017] The advantages and beneficial effects of this invention are as follows:

[0018] (1) The main raw materials used in this invention are widely available and inexpensive, and are non-toxic, harmless, non-flammable and non-explosive. The preparation and mixing process of the thermal insulation coating is simple, and will not produce toxic or harmful substances during use, and will not pollute the environment or endanger human health.

[0019] (2) The raw material described in this invention is a nano silica sol containing silica powder. By adding dispersant and thickener and mixing process, silica powder can be uniformly dispersed in silica sol, which can make the heat insulation coating more uniform.

[0020] (3) The heat-insulating coating described in this invention is mainly composed of nano-SiO2, which has a low thermal conductivity and good heat-insulating effect. It is beneficial to improve the heat utilization rate in the tobacco curing room, improve the quality of the tobacco leaves after curing, and reduce the energy consumption of coal, firewood and other materials.

[0021] (4) The film-forming agent described in this invention is applied to the inner wall of the tobacco curing barn after the silica sol is coated. The purpose is to enable the film-forming agent to cross-link with the nano-SiO2 in the silica sol, which can quickly solidify the coating and form a waterproof film. This can accelerate the formation of the heat insulation coating and improve the hydrophobicity of the coating, thereby ensuring that the heat and moisture inside the tobacco curing barn are not lost, and ensuring that the heat insulation coating can be stably used in a high humidity environment, thereby improving the service life of the heat insulation material on the wall of the tobacco curing barn. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a process flow diagram of the method of the present invention;

[0024] Figure 2 The temperature changes of the upper and lower three layers inside the tobacco curing barn after the heat-insulating coating prepared in Example 1 was applied to the inner wall of the tobacco curing barn;

[0025] Figure 3 The image shows the wetting results of the thermal insulation coating prepared in Example 1 after it was applied to the thermal insulation material.

[0026] Figure 4 The temperature changes of the upper and lower three layers inside the tobacco curing barn after the heat-insulating coating prepared in Example 2 was applied to the inner wall of the tobacco curing barn;

[0027] Figure 5 The image shows the wetting results of the thermal insulation coating prepared in Example 2 after it was applied to the thermal insulation material and then wetted with water.

[0028] Figure 6 The image shows the wetting results of the thermal insulation coating prepared in Example 3 after it was applied to the thermal insulation material. Detailed Implementation

[0029] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention. The present invention will be further described in detail below with reference to the embodiments.

[0030] The specific preparation and coating steps of the heat-insulating coating for the inner wall of a tobacco curing barn provided by this invention are as follows:

[0031] (1) The main raw materials of the thermal insulation coating include: nano-silica powder, nano-silica sol, dispersant, thickener and film-forming agent. Among them, the nano-silica powder is commercially available conventional nano-silica powder with an average particle size of 5nm to 10nm; the nano-silica sol is commercially available conventional nano-silica sol with a SiO2 concentration of 40% and an average SiO2 particle size of 30nm.

[0032] (2) By adding water, the viscosity of the nano silica sol was adjusted to 1.5 mPa·s to 2.0 mPa·s, and the pH of the nano silica sol was adjusted to 8.1 to 9.5 to obtain modified nano silica sol; and nano silica powder was added to the modified nano silica sol at a mass ratio of 0.5:1 to 1:1 with silica sol, and stirred evenly.

[0033] The modified nano-silica sol has a viscosity of 1.5 mPa·s to 2.0 mPa·s and a pH of 8.1 to 9.5; the average particle size of the nano-silica powder is 5 nm to 10 nm; and the stirring speed is 2000 r / min to 5000 r / min.

[0034] (3) Add the dispersant to the modified nano-silica sol and stir continuously; finally add the thickener to the nano-silica sol and stir to prepare a thermal insulation coating.

[0035] The dispersants and their order of addition are as follows: hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol, and hexadecyltrimethylammonium bromide are added sequentially; the mass ratio of each dispersant is 1:1:1; the total mass of the three dispersants is 1 / 10 to 1 / 20 of the total mass ratio of the modified silica sol and silica powder; the stirring speed is 2000 r / min to 5000 r / min; and the stirring time is 5 to 10 min.

[0036] The thickeners and their order of addition are as follows: dimethyl cellulose and polyvinyl alcohol are added sequentially; the mass ratio of each thickener is 1:1; the total mass of the two thickeners is 1 / 10 to 1 / 20 of the total mass ratio of modified silica sol and silica powder; the stirring speed is 2000 r / min to 5000 r / min; and the stirring time is 5 to 10 min.

[0037] (4) Preparation of film-forming agent: First, add polydimethylsiloxane to deionized water and stir evenly, then add emulsifier and stir at high speed to emulsify into polydimethylsiloxane emulsion.

[0038] The emulsified polydimethylsiloxane emulsion has a viscosity of 1.9 mPa·s to 3.8 mPa·s and a pH of 2.8 to 3.5.

[0039] (5) Apply the thermal insulation coating described in step 3 to the inner wall of the tobacco curing barn, and then apply the film-forming agent described in step 4 to the inner wall of the tobacco curing barn. After curing at room temperature for 3 to 6 hours, the thermal insulation layer will be solidified on the wall of the tobacco curing barn.

[0040] Example 1:

[0041] This embodiment uses nano-silica powder and nano-silica sol as main raw materials, hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol, and hexadecyltrimethylammonium bromide as dispersants, dimethyl cellulose and polyvinyl alcohol as thickeners, and modified dimethylsiloxane as a film-forming agent, according to... Figure 1 The process shown involves the preparation and application of the thermal insulation coating:

[0042] (1) By adding deionized water, the viscosity of the nano silica sol was adjusted to 1.5 mPa·s, and the pH of the nano silica sol was adjusted to 8.1 to form a modified nano silica sol; and nano silica powder with an average diameter of 5 nm was added to the modified nano silica sol at a mass ratio of 0.5:1, and stirred evenly at a stirring speed of 2000 r / min.

[0043] (2) According to the mass ratio of each dispersant being 1:1:1, the dispersants hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol and hexadecyltrimethylammonium bromide are added to the silica sol in sequence. The total mass of the three dispersants is 1 / 10 of the total mass ratio of the modified silica sol and silica powder. The silica sol is stirred at a stirring speed of 2000 r / min for 5 min.

[0044] (3) According to the mass ratio of each dispersant being 1:1, the thickeners dimethyl cellulose and polyvinyl alcohol are added to the silica sol in sequence. The total mass of the two thickeners is 1 / 10 of the total mass ratio of the modified silica sol and silica powder. The silica sol is stirred at a stirring speed of 2000 r / min for 5 min to prepare a nano-SiO2 thermal insulation coating.

[0045] (4) First, polydimethylsiloxane is added to deionized water and stirred evenly. Then, an emulsifier is added and stirred at high speed to emulsify, so as to prepare a polydimethylsiloxane emulsion with a viscosity of 1.9 mPa·s and a pH of 2.8, which is used as a film-forming agent.

[0046] (5) Apply the thermal insulation coating described in step 3 to the inner wall of the tobacco curing barn, and then apply the film-forming agent described in step 4 to the inner wall of the tobacco curing barn. After curing at room temperature for 3 hours, the thermal insulation layer will be solidified on the wall of the tobacco curing barn.

[0047] After applying the insulation coating to the tobacco curing barn, the actual tobacco curing process was carried out. A temperature recorder was used to record the temperature changes during a complete curing cycle, including the temperatures of the upper layer (near the roof) and the lower layer (near the ground) inside the barn. The results are as follows: Figure 2 As shown in the figure, after the start of curing, the temperature inside the tobacco curing barn gradually rises until it reaches the high-temperature zone required for curing after 15,000 minutes. This zone's temperature is mainly distributed between 60℃ and 70℃, and this temperature can be maintained for approximately 2,000 minutes before curing ends. Furthermore, the temperature changes in the upper and lower areas of the tobacco curing barn exhibit similar patterns and distributions, indicating stable internal temperature variations and good insulation. This demonstrates that the tobacco curing barn, after being coated with insulating paint, has a good insulation effect.

[0048] The hydrophobicity of coated insulation board materials was determined using a water wettability testing method. The procedure involved dropping water onto the surface of the coated insulation material and measuring the water contact angle using a contact angle meter (model: JC2000DM). The results are shown below. Figure 3 As shown in the figure, the water droplets do not spread on the surface of the insulation material and form a relatively obvious arc shape with an angle of 118°. This indicates that the insulation board material with coating has a strong hydrophobic effect, which helps to extend the service life of the insulation material in high humidity environments.

[0049] Example 2:

[0050] This embodiment uses nano-silica powder and nano-silica sol as main raw materials, hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol, and hexadecyltrimethylammonium bromide as dispersants, dimethyl cellulose and polyvinyl alcohol as thickeners, and modified dimethylsiloxane as a film-forming agent, according to... Figure 1 The process shown involves the preparation and application of the thermal insulation coating:

[0051] (1) By adding deionized water, the viscosity of the nano silica sol was adjusted to 2.0 mPa·s, and the pH of the nano silica sol was adjusted to 9.5 to obtain modified nano silica sol; and nano silica powder with an average diameter of 5 nm was added to the modified nano silica sol at a mass ratio of 1:1, and stirred evenly at a stirring speed of 5000 r / min.

[0052] (2) According to the mass ratio of each dispersant being 1:1:1, the dispersants hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol and hexadecyltrimethylammonium bromide are added to the silica sol in sequence. The total mass of the three dispersants is 1 / 20 of the total mass ratio of the modified silica sol and silica powder. The silica sol is stirred at a stirring speed of 5000 r / min for 10 min.

[0053] (3) According to the mass ratio of each dispersant being 1:1, the thickeners dimethyl cellulose and polyvinyl alcohol are added to the silica sol in sequence. The total mass of the two thickeners is 1 / 20 of the total mass ratio of the modified silica sol and silica powder. The silica sol is stirred at a stirring speed of 5000 r / min for 10 min to prepare a nano-SiO2 thermal insulation coating.

[0054] (4) First, polydimethylsiloxane is added to deionized water and stirred evenly. Then, an emulsifier is added and emulsified by high-speed stirring to prepare a polydimethylsiloxane emulsion with a viscosity of 3.8 mPa·s and a pH of 3.5, which is used as a film-forming agent.

[0055] (5) Apply the thermal insulation coating described in step 3 to the inner wall of the tobacco curing barn, and then apply the film-forming agent described in step 4 to the inner wall of the tobacco curing barn. After curing at room temperature for 6 hours, the thermal insulation layer will be solidified on the wall of the tobacco curing barn.

[0056] After applying the insulation coating to the tobacco curing barn, the actual tobacco curing process was carried out. A temperature recorder was used to record the temperature changes during a complete curing cycle, including the temperatures of the upper layer (near the roof) and the lower layer (near the ground) inside the barn. The results are as follows: Figure 4 As shown. Since the time for each tobacco curing is uncertain, therefore... Figure 2 and Figure 4 In comparison, their horizontal axes are not entirely the same. As can be seen from the graph, after the start of curing, the temperature inside the tobacco curing barn gradually rises until, after 12,000 minutes, the temperature reaches the high-temperature zone required for curing. This zone's temperature is mainly distributed between 60℃ and 70℃, and this temperature can be maintained for approximately 2,000 minutes until curing ends. Furthermore, the temperature changes in the upper and lower areas of the tobacco curing barn show similar patterns and distributions, indicating stable internal temperature changes and good insulation. This demonstrates that the tobacco curing barn, after being coated with insulating paint, has a good insulation effect.

[0057] The hydrophobicity of coated insulation board materials was determined using a water wettability testing method. The procedure involved dropping water onto the surface of the coated insulation material and measuring the water contact angle using a contact angle meter (model: JC2000DM). The results are shown below. Figure 5 As shown in the figure, the water droplets do not spread on the surface of the insulation material and form a relatively obvious arc shape with an angle of 115°. This indicates that the insulation board material with coating has a strong hydrophobic effect, which helps to extend the service life of the insulation material in high humidity environments.

[0058] Example 3:

[0059] This embodiment uses nano-silica powder and nano-silica sol as main raw materials, hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol, and hexadecyltrimethylammonium bromide as dispersants, dimethyl cellulose and polyvinyl alcohol as thickeners, and modified dimethylsiloxane as a film-forming agent, according to... Figure 1 The process shown involves the preparation and application of the thermal insulation coating:

[0060] (1) By adding deionized water, the viscosity of the nano silica sol was adjusted to 2.5 mPa·s, and the pH of the nano silica sol was adjusted to 9.7 to obtain modified nano silica sol; and nano silica powder with an average diameter of 5 nm was added to the modified nano silica sol at a mass ratio of 1:1, and stirred evenly at a stirring speed of 5000 r / min.

[0061] (2) According to the mass ratio of each dispersant being 1:1:1, the dispersants hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol and hexadecyltrimethylammonium bromide are added to the silica sol in sequence. The total mass of the three dispersants is 1 / 20 of the total mass ratio of the modified silica sol and silica powder. The silica sol is stirred at a stirring speed of 5000 r / min for 10 min.

[0062] (3) According to the mass ratio of each dispersant being 1:1, the thickeners dimethyl cellulose and polyvinyl alcohol are added to the silica sol in sequence. The total mass of the two thickeners is 1 / 20 of the total mass ratio of the modified silica sol and silica powder. The silica sol is stirred at a stirring speed of 5000 r / min for 10 min to prepare a nano-SiO2 thermal insulation coating.

[0063] (4) First, polydimethylsiloxane is added to deionized water and stirred evenly. Then, an emulsifier is added and emulsified by high-speed stirring to prepare a polydimethylsiloxane emulsion with a viscosity of 3.8 mPa·s and a pH of 3.5, which is used as a film-forming agent.

[0064] (5) Apply the thermal insulation coating described in step 3 to the inner wall of the tobacco curing barn, and then apply the film-forming agent described in step 4 to the inner wall of the tobacco curing barn. After curing at room temperature for 6 hours, the thermal insulation layer will be solidified on the wall of the tobacco curing barn.

[0065] The hydrophobicity of coated insulation board materials was determined using a water wettability testing method. The procedure involved dropping water onto the surface of the coated insulation material and measuring the water contact angle using a contact angle meter (model: JC2000DM). The results are shown below. Figure 6As shown in the figure, the water droplets do not spread on the surface of the insulation material and form a relatively obvious arc shape with an angle of only 80°. This indicates that the insulation material has poor hydrophobicity after coating, and in actual high-humidity environments, water infiltration can easily reduce the lifespan of the insulation material. Furthermore, this also shows that altering the viscosity and pH of the modified nano-silica sol outside the parameters of this invention will adversely affect film formation, thus impacting the hydrophobicity of the prepared coating.

[0066] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A heat-insulating coating for the inner wall of a tobacco curing barn, characterized in that, The prepared material consists of nano-silica powder, nano-silica sol, dispersant, thickener, and film-forming agent. The viscosity of the nano-silica sol was adjusted to 1.5 mPa·s~2.0 mPa·s, and the pH of the nano-silica sol was adjusted to 8.1~9.5 to obtain the modified nano-silica sol. Then, nano-silica powder was added to the modified nano-silica sol, and then dispersant and thickener were added to the modified nano-silica sol in sequence to obtain thermal insulation coating; The insulation coating on the inner wall of the tobacco curing barn consists of an insulation coating layer and a film-forming agent layer; The nano-silicon powder has a particle size of 5 nm to 10 nm, and the mass ratio of the nano-silicon powder to the nano-silicon sol is (0.5~1):1; The dispersant comprises hexadecyltrimethylammonium chloride, sodium carboxyethylsilanetriol, and hexadecyltrimethylammonium bromide in a mass ratio of 1:1:

1. The total mass ratio of the dispersant to the total mass of the modified nano-silica sol and nano-silica powder is 1 / (10~20). The thickener comprises dimethyl cellulose and polyvinyl alcohol in a mass ratio of 1:1; The ratio of the total mass of the thickener to the total mass of the modified nano-silica sol and nano-silica powder is 1 / (10~20). The preparation of the film-forming agent includes: first, stirring polydimethylsiloxane in water until uniform, and then adding an emulsifier to emulsify it into a polydimethylsiloxane emulsion.

2. The heat-insulating coating for the inner wall of the tobacco curing barn according to claim 1, characterized in that, The film-forming agent has a viscosity of 1.9 mPa·s to 3.8 mPa·s and a pH of 2.8 to 3.

5.

3. The heat-insulating coating for the inner wall of the tobacco curing barn according to claim 1 or 2, characterized in that, Both the thermal insulation coating and the film-forming agent require high-speed stirring during the preparation process. The high-speed stirring speed is 2000 r / min to 5000 r / min, and the stirring time is 5 to 10 min.

4. The method for preparing the heat-insulating coating on the inner wall of the tobacco curing barn according to any one of claims 1-3, characterized in that, include: The thermal insulation coating is applied to the inner wall of the room to be insulated to form a thermal insulation coating layer. Then, a film-forming agent is applied to the outside of the thermal insulation coating layer to form a film-forming agent layer. After curing at room temperature for 3-6 hours, it is ready.

Images