Reflective thermal insulation coating and preparation method thereof

Abstract

The invention discloses a reflective heat-insulation coating and a preparation method thereof, and the reflective heat-insulation coating comprises the following components in percentage by mass: 10-50% of flaky barium sulfate; the particle size distribution of the flaky barium sulfate is 400 nm to 15 [mu] m. The flaky barium sulfate with a wide particle size range is used as a reflective heat insulation filler of the coating, so that the lightness, reflectivity, reflectivity and heat insulation effect of the coating can be effectively improved on the premise of a relatively large addition amount.

Description

Technical Field

[0001] The invention belongs to the technical field of reflective heat-insulating coatings, and in particular relates to a reflective heat-insulating coating and a preparation method thereof. Background Art

[0002] Thermal insulation paint is a new type of functional water-based paint that can block and reflect near-infrared heat from sunlight. It can be applied on the surface of buildings to insulate and cool down, thereby achieving energy conservation and consumption reduction. It also has waterproof, rust-proof and anti-corrosion functions, with a short construction period and significant results.

[0003] Thermal insulation coatings are mainly divided into two categories: insulating conductive type and reflective type. Insulating conductive type thermal insulation coatings usually use silicates as reflective thermal insulation fillers, but the thermal insulation effect is limited. Reflective thermal insulation coatings usually use metals or metal oxides as reflective thermal insulation fillers, such as zinc powder, aluminum powder, silver powder and nano-titanium dioxide. Reflective thermal insulation coatings have the effect of efficiently reflecting sunlight and can significantly reduce heat accumulation. Nano-titanium dioxide has become a commonly used reflective filler due to its strong hiding power and stability, but the high cost of nano-titanium dioxide limits its application in thermal insulation coatings.

[0004] Barium sulfate is often used to replace titanium dioxide as a reflective heat-insulating filler for coatings due to its low oil absorption, large filling volume, low cost and high whiteness. It can improve the gloss of coatings, but excessive addition of barium sulfate will reduce the thermal insulation of coatings. In order to solve the problem of excessive addition of barium sulfate leading to reduced thermal insulation of coatings, the existing technology uses barium sulfate of a certain particle size to prepare coatings, which effectively solves the problem of reduced thermal insulation of coatings. However, it is difficult to ensure that the coating has a high reflectivity and reflectivity while effectively solving the thermal insulation performance of the coating. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, a reflective thermal insulation coating is provided. By using flaky barium sulfate with a wide range of particle sizes as a reflective thermal insulation filler of the coating, the brightness, reflectivity, reflectance and thermal insulation effect of the coating can be effectively improved under the premise of a large addition amount.

[0006] The object of the present invention is to provide a flaky barium sulfate, wherein the particle size distribution of the flaky barium sulfate is 400nm-15μm.

[0007] In some embodiments of the present invention, the D 50 >10μm.

[0008] Another object of the present invention is to provide a method for preparing flaky barium sulfate, comprising the following steps:

[0009] Dissolve sodium sulfate and sodium chloride in a mass ratio of 1:4 to 1:10 in water, stir to dissolve, add barium chloride, stir to mix, heat to react, and purify to obtain flaky barium sulfate.

[0010] In some embodiments of the present invention, the mass ratio of sodium sulfate to barium chloride is 1:1.2~2.

[0011] In some embodiments of the present invention, the temperature of the heating reaction is 150-200° C., and the reaction time is 24-48 hours.

[0012] In some embodiments of the present invention, the purification includes cooling to room temperature, collecting the precipitate, filtering, washing, and drying.

[0013] Another object of the present invention is to provide a reflective heat-insulating coating, which comprises 10 to 50% of the flaky barium sulfate in terms of mass percentage.

[0014] In some embodiments of the present invention, the reflective thermal insulation coating also includes 20-60% water-based resin emulsion.

[0015] In some embodiments of the present invention, the water-based resin emulsion is selected from at least one of pure acrylic emulsion, styrene acrylic emulsion, silicone acrylic emulsion and acetic acid acrylic emulsion.

[0016] In some embodiments of the present invention, the aqueous resin emulsion is selected from silicone acrylic emulsion.

[0017] In some embodiments of the present invention, the reflective heat-insulating coating further includes 0.5-2.5% thickener, 0.5-2.5% plasticizer, 0.5-1% wetting agent, 0.5-1% defoaming agent, 0.1-0.5% bactericide, and the balance deionized water.

[0018] In some embodiments of the present invention, the thickener is selected from at least one of polyvinyl alcohol, polyacrylate, bentonite, cellulose, and polyurethane.

[0019] In some embodiments of the present invention, the plasticizer is selected from at least one of phthalates, fatty acid amides, siloxanes, chlorinated petroleum hydrocarbons, epoxy resins, polyurethanes, acrylates, glycerides, and vegetable oils.

[0020] In some embodiments of the present invention, the wetting agent is selected from at least one of alkyl polyoxyethylene ethers, phosphites, acrylates, ethylene glycol ethers, propylene glycol ethers, polypropylene glycol, Carbowet GA-100, Dynol 360, Dynol 604, Dynol 607, and Surfynol 104E.

[0021] In some embodiments of the present invention, the defoaming agent is selected from at least one of zinc stearate, aluminum stearate, potassium stearate, sodium stearate, polydimethylsiloxane, white oil, polyoxyethylene fatty alcohol ether, polyoxypropylene fatty alcohol ether, ethoxylated silicone oil, and silicone polyoxyethylene.

[0022] In some embodiments of the present invention, the fungicide is selected from at least one of copper pyrithione, LM-7012, kasone, and methylisothiazolinone.

[0023] Another object of the present invention is to provide a method for preparing the reflective heat-insulating coating, comprising the following steps:

[0024] S1. The aqueous resin emulsion, deionized water, a wetting agent, a defoamer and a fungicide are mixed and stirred to obtain a mixture;

[0025] S2. Add flaky barium sulfate to the mixture, stir, then add a thickener and a plasticizer, stir evenly, and obtain a reflective heat-insulating coating.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention adopts flaky barium sulfate as a reflective heat-insulating filler. The flaky barium sulfate has a wider particle size distribution range and can better reflect and scatter visible light and infrared rays in sunlight, effectively preventing the accumulation of solar heat on the surface of objects, and significantly improving the heat-insulating performance of the coating.

[0028] (2) The preparation method of the reflective heat-insulating coating provided by the present invention is simple in process and easy to operate, which is conducive to industrial production and meets market demand. In addition, the coating also has good coating properties, such as flatness, density, and small cracks, which further improves its reliability and durability in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the SEM image of the flaky barium sulfate prepared in Example 1.

[0030] Figure 2 This is an SEM image of the coating surface made of the reflective thermal insulation coating prepared in Example 4.

[0031] Figure 3 This is the SEM image of the flaky barium sulfate prepared in Comparative Example 1.

[0032] Figure 4 This is the SEM image of barium sulfate prepared in Comparative Example 2.

[0033] Figure 5 This is the TEM image of barium sulfate prepared in Comparative Example 3. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment provides a method for preparing flaky barium sulfate, and the specific preparation steps are as follows:

[0037] S1. Weigh 2.84 kg of sodium sulfate and 14.20 kg of sodium chloride, stir in 130 kg of water until dissolved, add 4.16 kg of barium chloride, continue stirring for 15 min, and obtain a mixture;

[0038] S2. The mixture in step S1 was transferred to a high-pressure reactor, the temperature of the reactor was raised to 160°C, the temperature was kept for 36 hours, the temperature was naturally cooled to room temperature, and the precipitate was collected.

[0039] S3. The precipitate in step S2 is filtered, washed with pure water 5 times, and dried at 120° C. to obtain flaky barium sulfate.

[0040] Figure 1 This is a scanning electron microscope image of the flaky barium sulfate described in Example 1. Figure 1 As shown, the flake barium sulfate particles in Example 1 have different sizes, and the D 50 The particle size is 10.74 μm, and the particle size distribution is 400 nm ~ 15 μm, with a large particle size fluctuation range.

[0041] Example 2

[0042] This embodiment provides a method for preparing flaky barium sulfate, and the specific preparation steps are as follows:

[0043] S1. Weigh 2.84 kg of sodium sulfate and 28.4 kg of sodium chloride, stir in 130 kg of water until dissolved, add 4.16 kg of barium chloride, continue stirring for 15 min, and obtain a mixture;

[0044] S2. The mixture in step S1 is transferred to a high-pressure reactor, the temperature of the reactor is raised to 200°C, the temperature is kept for 48 hours, the temperature is naturally cooled to room temperature, and the precipitate is collected.

[0045] S3. The precipitate in step S2 is filtered, the precipitate is washed with pure water 5 times, and dried at 120°C to obtain flaky barium sulfate. 50The particle size is 11.06μm, and the particle size distribution is 400nm~15μm, with a large particle size fluctuation range.

[0046] Example 3

[0047] This embodiment provides a method for preparing flaky barium sulfate, and the specific preparation steps are as follows:

[0048] S1. Weigh 2.84 kg of sodium sulfate and 11.36 kg of sodium chloride, stir in 130 kg of water until dissolved, add 4.16 kg of barium chloride, continue stirring for 15 min, and obtain a mixture;

[0049] S2. The mixture in step S1 was transferred into a high-pressure reactor, the temperature of the reactor was raised to 150°C, the temperature was kept for 24 hours, the temperature was naturally cooled to room temperature, and the precipitate was collected.

[0050] S3. The precipitate in step S2 is filtered, the precipitate is washed with pure water 5 times, and dried at 120°C to obtain flaky barium sulfate. 50 The particle size is 11.13 μm, and the particle size distribution is 400 nm ~ 15 μm, with a large particle size fluctuation range.

[0051] Example 4

[0052] This embodiment provides a method for preparing a reflective heat-insulating coating, and the specific preparation steps are as follows:

[0053] S1. By mass percentage, 40% pure acrylic emulsion, 26.25% deionized water, 0.75% Carbowet GA-100, 0.75% zinc stearate and 0.25% LM-7012 were mixed to obtain a mixture;

[0054] S2. In terms of mass percentage, 30% of the flaky barium sulfate prepared in Example 1 is added to the mixture in step S1, and the mixture is stirred. Then, 1% of bentonite and 1% of fatty acid amide are added, and the mixture is stirred evenly to obtain a reflective heat-insulating coating.

[0055] Figure 2 This is a SEM image of the coating surface made of the reflective heat-insulating coating prepared in Example 4. Figure 2 It can be seen that the coating surface is smooth and dense, the cracks are small, and the coating quality is excellent.

[0056] Example 5

[0057] This embodiment provides a method for preparing a reflective heat-insulating coating, and the specific preparation steps are as follows:

[0058] S1. By mass percentage, 60% styrene acrylic emulsion, 26.25% deionized water, 0.75% Dynol 607, 0.75% sodium stearate and 0.25% Kasson were mixed to obtain a mixture;

[0059] S2. In terms of mass percentage, 10% of the flaky barium sulfate prepared in Example 2 is added to the mixture in step S1, stirred, and then 1% of polyvinyl alcohol and 1% of epoxy resin are added, stirred evenly, to obtain a reflective heat-insulating coating.

[0060] Example 6

[0061] This embodiment provides a method for preparing a reflective heat-insulating coating, and the specific preparation steps are as follows:

[0062] S1. By mass percentage, 20% of acetic acid propylene emulsion, 24.4% deionized water, 0.6% Carbowet GA-100, 0.6% zinc stearate and 0.4% LM-7012 were mixed to obtain a mixture;

[0063] S2. In terms of mass percentage, 50% of the flaky barium sulfate prepared in Example 3 is added to the mixture in step S1, and the mixture is stirred. Then, 2% of bentonite and 2% of fatty acid amide are added, and the mixture is stirred evenly to obtain a reflective heat-insulating coating.

[0064] Example 7

[0065] This embodiment provides a reflective heat-insulating coating, which differs from the embodiment 4 only in that the pure acrylic emulsion in step S1 of the embodiment 4 is replaced with a silicone acrylic emulsion. The specific preparation steps are as follows:

[0066] S1. By mass percentage, 40% of silicone acrylic emulsion, 26.25% of deionized water, 0.75% of Carbowet GA-100, 0.75% of zinc stearate and 0.25% of LM-7012 were mixed to obtain a mixture;

[0067] S2. In terms of mass percentage, 30% of the flaky barium sulfate prepared in Example 1 is added to the mixture in step S1, and the mixture is stirred. Then, 1% of bentonite and 1% of fatty acid amide are added, and the mixture is stirred evenly to obtain a reflective heat-insulating coating.

[0068] Comparative Example 1

[0069] This comparative example provides a flaky barium sulfate, which differs from Example 1 only in the mass ratio of sodium sulfate to sodium chloride. The specific preparation steps are as follows:

[0070] S1. Weigh 2.84 kg of sodium sulfate and 2.84 kg of sodium chloride, stir in 130 kg of water until dissolved, add 4.16 kg of barium chloride under stirring, continue stirring for 15 min to obtain a mixture;

[0071] S2. The mixture in step S1 was transferred to a high-pressure reactor, the temperature of the reactor was raised to 160°C, the temperature was kept for 36 hours, the temperature was naturally cooled to room temperature, and the precipitate was collected.

[0072] S3. The precipitate in step S2 is filtered, washed with pure water 5 times, and dried at 120° C. to obtain flaky barium sulfate.

[0073] Figure 3 This is a scanning electron microscope image of the flaky barium sulfate prepared in Comparative Example 1. Figure 3 It can be seen that when the amount of sodium chloride added is reduced, the obtained barium sulfate is still in the form of flakes, but the particle size is significantly reduced, with the maximum particle size being about 5 μm. 50 The particle size is 3.58μm, and the particle size distribution is between 500nm and 5μm, with a small particle size fluctuation range.

[0074] Comparative Example 2

[0075] This comparative example provides a barium sulfate, which is different from Example 1 in that no sodium chloride is added, the heating reaction temperature is changed from 160° C. to 80° C., and the heating reaction time is changed from 36 h to 24 h. The specific preparation steps are as follows:

[0076] S1. Weigh 2.84 kg of sodium sulfate, stir in 130 kg of water until dissolved, add 4.16 kg of barium chloride under stirring, continue stirring for 15 min to obtain a mixture;

[0077] S2. The mixture in step S1 was transferred into a high-pressure reactor, the temperature of the reactor was raised to 80°C, the temperature was kept for 24 hours, the temperature was naturally cooled to room temperature, and the precipitate was collected.

[0078] S3. The precipitate in step S2 is filtered, washed with pure water 5 times, and dried at 120° C. to obtain barium sulfate.

[0079] Figure 4 This is a scanning electron microscope image of barium sulfate prepared in Comparative Example 2. Figure 4 It can be seen that the D of barium sulfate 50 The particle size is 1.62μm, and the particle size distribution is mainly between 1~2μm.

[0080] Comparative Example 3

[0081] This comparative example provides a barium sulfate, which is different from Example 1 in that the barium chloride in step S1 is replaced by concentrated sulfuric acid, and the sodium sulfate and sodium chloride are replaced by barium hydroxide octahydrate. The specific preparation steps are as follows:

[0082] S1. Weigh 3.15 kg of barium hydroxide octahydrate, stir it in 56 kg of water until it dissolves, and obtain a barium hydroxide solution; weigh 9.5 kg of pure water and 1.00 kg of 98% concentrated sulfuric acid, mix and stir evenly, and obtain a sulfuric acid solution.

[0083] S2. The barium hydroxide solution and sulfuric acid solution in step S1 are transferred to a high-pressure reactor, and 10 kg of water is added. The addition time of the mixture and the sulfuric acid solution is about 30 minutes. After the addition is completed, stir for 30 minutes and collect the precipitate.

[0084] S3. The precipitate in step S2 is filtered, washed with pure water 5 times, and dried at 100° C. to obtain barium sulfate.

[0085] Figure 5 This is a perspective electron microscope image of the barium sulfate prepared in Comparative Example 3. Figure 5 It can be seen that the D of barium sulfate 50 The particle size is 410nm and the particle size is in the range of 100~500nm.

[0086] Comparative Example 4

[0087] This comparative example provides a reflective heat-insulating coating, which differs from Example 4 only in that the flaky barium sulfate prepared in Example 1 in step S2 of Example 4 is replaced by the flaky barium sulfate prepared in Comparative Example 1. The specific preparation steps are as follows:

[0088] S1. By mass percentage, 40% pure acrylic emulsion, 26.25% deionized water, 0.75% Carbowet GA-100, 0.75% zinc stearate and 0.25% LM-7012 were mixed to obtain a mixture;

[0089] S2. In terms of mass percentage, 30% of the flaky barium sulfate prepared in Comparative Example 1 was added to the mixture in step S1, and stirred. Then, 1% of bentonite and 1% of fatty acid amide were added, and stirred evenly to obtain a reflective heat-insulating coating.

[0090] Comparative Example 5

[0091] This comparative example provides a reflective heat-insulating coating, which differs from Example 4 only in that the flaky barium sulfate prepared in Example 1 in step S2 of Example 4 is replaced with the barium sulfate prepared in Comparative Example 2. The specific preparation steps are as follows:

[0092] S1. By mass percentage, 40% pure acrylic emulsion, 26.25% deionized water, 0.75% Carbowet GA-100, 0.75% zinc stearate and 0.25% LM-7012 were mixed to obtain a mixture;

[0093] S2. In terms of mass percentage, 30% of the barium sulfate prepared in Comparative Example 2 was added to the mixture in step S1, and stirred. Then, 1% of bentonite and 1% of fatty acid amide were added, and stirred evenly to obtain a reflective heat-insulating coating.

[0094] Comparative Example 6

[0095] This comparative example provides a reflective heat-insulating coating, which differs from Example 4 only in that the flaky barium sulfate prepared in Example 1 in step S2 of Example 4 is replaced with the barium sulfate prepared in Comparative Example 3. The specific preparation steps are as follows:

[0096] S1. By mass percentage, 40% pure acrylic emulsion, 26.25% deionized water, 0.75% Carbowet GA-100, 0.75% zinc stearate and 0.25% LM-7012 were mixed to obtain a mixture;

[0097] S2. In terms of mass percentage, 30% of the barium sulfate prepared in Comparative Example 3 was added to the mixture in step S1, and the mixture was stirred. Then, 1% of bentonite and 1% of fatty acid amide were added, and the mixture was stirred evenly to obtain a reflective heat-insulating coating.

[0098] Performance Testing

[0099] The reflective heat-insulating coatings prepared in the above Examples 4 to 7 and Comparative Examples 4 to 6 were subjected to performance tests. Specifically, the above coatings were respectively coated on the same aluminum plate using an applicator to form a dry film coating with a thickness of 500 μm, and the brightness (L*), solar reflectance, near-infrared reflectance, hemispherical emissivity, and heat-insulating performance of the coatings were tested.

[0100] Brightness was tested using a colorimeter.

[0101] The solar reflectance and near-infrared reflectance of the coating are tested according to the provisions of 6.4 of JG / T235-2014.

[0102] The hemispherical emissivity of the coating is tested according to the provisions of 6.5 of JG / T235-2014.

[0103] The thermal insulation temperature difference of the coating is tested according to the provisions of Appendix B of GBT25261-2018.

[0104] The test results are shown in Table 1 below:

[0105] Table 1. Performance test results of reflective thermal insulation coatings.

[0106] sample Lightness L* Solar reflectance (%) Near infrared reflectance (%) Hemispherical reflectivity (%) Insulation temperature difference (℃) Example 4 99.63 94.2 93.8 95.3 24.5 Example 5 99.62 94.3 93.6 95.6 24.3 Example 6 99.59 94.1 93.7 95.4 24.6 Example 7 99.57 98.6 97.3 91.7 27.8 Comparative Example 4 99.37 82.4 82.0 82.9 15.8 Comparative Example 5 99.11 81.1 79.6 79.5 13.2 Comparative Example 6 98.24 78.3 71.7 73.3 8.9

[0107] As shown in Table 1, the lightness L* values ​​of the reflective heat-insulating coatings prepared in Examples 4 to 7 are all close to 99.6, showing high brightness characteristics; the solar reflectance is all above 94%, showing good solar radiation reflection ability; the near-infrared reflectance is all close to 93.7%, with high near-infrared radiation reflection performance; the hemispherical emissivity is all above 95%, with high thermal radiation emission ability; the thermal insulation temperature difference is all above 24°C, showing good thermal insulation performance. And the lightness, solar reflectance, far-infrared reflectance, hemispherical emissivity and thermal insulation temperature difference of the reflective heat-insulating coatings prepared in Examples 4 to 7 of the present invention are all better than those prepared in Comparative Examples 4 to 6 of the present invention, and have excellent thermal insulation performance.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the specification of this application, the technicians can still modify or replace the specific implementation mode of the present invention with equivalents, but these modifications or changes do not deviate from the scope of protection of the pending claims of the present application.

Claims

1. A flaky barium sulfate, It is characterized in that The particle size distribution of the flaky barium sulfate is 400nm-15μm.

2. The flaky barium sulfate according to claim 1, It is characterized in that The D of the flake barium sulfate 50 >10μm.

3. A method for preparing the flaky barium sulfate according to any one of claims 1 to 2, It is characterized in that The following steps are involved: Sodium sulfate and sodium chloride in a mass ratio of 1:4 to 1:10 are dissolved in water, stirred to dissolve, barium chloride is added, stirred and mixed, heated to react, and purified to obtain flaky barium sulfate.

4. The preparation method according to claim 3, It is characterized in that The mass ratio of the sodium sulfate to the barium chloride is 1:1.2-2.

5. The preparation method according to claim 3, It is characterized in that The heating reaction temperature is 150-200° C. and the time is 24-48 hours.

6. A reflective heat-insulating coating, It is characterized in that Calculated by mass percentage, it comprises 10-50% of the flaky barium sulfate described in any one of claims 1-2.

7. The reflective heat-insulating coating according to claim 6, It is characterized in that The reflective heat-insulating material also includes 20-60% of an aqueous resin emulsion, and the aqueous resin emulsion is selected from at least one of pure acrylic emulsion, styrene acrylic emulsion, silicone acrylic emulsion and acetate acrylic emulsion.

8. The reflective heat-insulating coating according to claim 7, It is characterized in that The aqueous resin emulsion is selected from silicone acrylic emulsion.

9. The reflective heat-insulating coating according to claim 6, It is characterized in that The reflective heat-insulating coating also includes 0.5-2.5% thickener, 0.5-2.5% plasticizer, 0.5-1% wetting agent, 0.5-1% defoaming agent, 0.1-0.5% bactericide, and the balance deionized water.

10. A method for preparing the reflective heat-insulating coating according to any one of claims 6 to 9, It is characterized in that The steps include: S1. The aqueous resin emulsion, deionized water, a wetting agent, a defoamer and a fungicide are mixed and stirred to obtain a mixture; S2. Add flaky barium sulfate to the mixture, stir, then add a thickener and a plasticizer, stir evenly, and obtain a reflective heat-insulating coating.

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