An ultra-lightweight thermal insulation coating and a preparation method thereof

Abstract

The application belongs to the field of coating preparation, and particularly relates to a super-light heat-insulating coating and a preparation method thereof, which comprises 20-60 parts of a film forming agent, 10-20 parts of hollow microspheres, 2-4 parts of hydrophilic silicon dioxide, 2-6 parts of hydrophobic silicon dioxide, 2-7 parts of calcium carbonate whiskers and 2-6 parts of an additive according to mass fraction. The preparation method is simple, the obtained super-light heat-insulating coating is combined with fillers of various sizes and shapes, and the coating can avoid the phenomena of delamination and uneven dispersion, and has the functions of super-lightness and heat insulation.

Description

Technical Field

[0001] The present invention belongs to the field of coating preparation, and in particular relates to an ultra-lightweight thermal insulation coating and a preparation method thereof. Background Art

[0002] Air conditioning and heating account for the vast majority of building energy consumption. Using thermal insulation coatings on building walls helps maintain a comfortable internal temperature, reducing heat loss from air conditioning and heating, and ultimately achieving energy savings. Coatings applied to vertical walls must have a low density to prevent runoff and agglomeration. Thermal insulation coatings primarily consist of resins, pigments, additives, and fillers. Functional fillers not only provide bulk to reduce costs, but also must ensure lightweighting and reduce the thermal conductivity of the coating. For example, the addition of hollow glass microspheres or sepiolite can improve the coating's thermal insulation. However, to ensure integrity during mixing, the particle size and wall thickness of hollow glass microspheres cannot be further reduced. Voids created by particle accumulation also affect the coating's thermal insulation properties. Using fillers with similar sizes and properties to glass microspheres alone will only have limited effect on improving the coating's thermal insulation performance. Summary of the Invention

[0003] To address the limited thermal insulation performance of coatings using glass microspheres in existing technologies, the present invention provides a thermal insulation coating that combines thermal insulation materials of various sizes and shapes, has strong compatibility between the raw materials, and is lightweight, as well as a method for preparing the coating. The technical solution is as follows:

[0004] An ultra-light thermal insulation coating comprises, by weight, 20 to 60 parts of a film-forming agent, 10 to 20 parts of hollow microspheres, 2 to 4 parts of hydrophilic silica, 2 to 6 parts of hydrophobic silica, 2 to 7 parts of calcium carbonate whiskers and 2 to 6 parts of additives.

[0005] Furthermore, the auxiliary agent includes a dispersant, a defoaming agent and a wetting agent.

[0006] A preparation method of the above-mentioned ultra-light thermal insulation coating is as follows: the additive is fully dispersed in water, hydrophilic silica and hydrophobic silica are added, and after complete addition, the rotation speed is increased to 1000-1500r / min. After the raw materials are evenly mixed, defoaming is performed, and after defoaming, a film-forming agent and a film-forming auxiliary agent are added to obtain a base slurry; hollow microspheres and calcium carbonate whiskers are added to the base slurry under medium-speed stirring, and the coating is obtained after complete dispersion.

[0007] Furthermore, the rotation speed is increased at a rate of 100 to 300 r / min per minute.

[0008] Furthermore, the preparation of the calcium carbonate whiskers comprises the following steps:

[0009] a. Prepare an aqueous solution of sodium dodecyl sulfate and add part of magnesium chloride while stirring. Mix thoroughly to obtain a precursor solution.

[0010] b. Take the remaining magnesium chloride and prepare a magnesium chloride solution; prepare a calcium hydroxide suspension, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30-40°C for 1-3 hours; then add the magnesium chloride solution and react at 70-85°C for 4-8 hours; after filtering, wash the precipitate thoroughly to obtain calcium carbonate whiskers.

[0011] Furthermore, the concentration of the sodium dodecyl sulfate aqueous solution in step a is 6 to 15 g / L; the mass ratio of the sodium dodecyl sulfate in step a to the calcium hydroxide in step b is 1.5 to 2.5:1; the mass ratio of part of the magnesium chloride in step a to the calcium hydroxide in step b is 0.2 to 0.8:1; and the mass ratio of the remaining magnesium chloride in step b to calcium hydroxide is 0.5 to 1.5:1.

[0012] Furthermore, the calcium oxide obtained by calcination is added to water, the system is kept at a slight boil, and digested for 1 to 2 hours to obtain a calcium hydroxide suspension.

[0013] Furthermore, the silica is modified with a hydrophobic silane coupling agent to obtain hydrophobic silica; and the silica is modified with an amino-containing silane coupling agent to obtain hydrophilic silica.

[0014] Furthermore, the hollow microspheres are glass microspheres; the glass microspheres are modified, comprising the following steps: placing the glass microspheres in concentrated acetic acid and stirring at a low speed for 12 to 24 hours; adding ethanol to dilute the pH of the system to 4 to 6, adding 3-aminopropyltriethoxysilane, reacting for 12 to 24 hours, rinsing and drying, thereby completing the modification.

[0015] Furthermore, the volume ratio of acetic acid to water in the concentrated acetic acid is 10-2:1; and the mass ratio of the glass microspheres to 3-aminopropyltriethoxysilane is 1:1-2.

[0016] By adopting the above scheme, the method of the present invention has the following advantages:

[0017] 1. In the ultra-lightweight thermal insulation coating of the present invention, hollow glass microspheres are arranged to form the main body of the filler, and the silica and whiskers with finer particles can be inserted into the gaps between the microspheres, reducing heat convection inside the coating and improving the thermal insulation performance of the filler.

[0018] 2. The ultra-lightweight thermal insulation coating of the present invention utilizes a combination of fillers of various sizes and shapes to prevent delamination and uneven dispersion of the coating. Furthermore, the calcium carbonate whiskers enhance the mechanical properties of the coating and reduce the likelihood of cracks forming in the coating.

[0019] 3. The calcium carbonate whiskers added in the present invention eventually form a hollow structure under the attraction of sodium dodecyl sulfate. The density of the obtained calcium carbonate whiskers is significantly lower than that of conventional calcium carbonate, which can further improve the thermal insulation effect of the coating.

[0020] 4. The present invention introduces magnesium ions during the growth of calcium carbonate. The generated magnesium hydroxide promotes the growth of calcium carbonate in a single direction and combines with sodium dodecyl sulfate to form hollow whiskers.

[0021] 5. The addition of nano calcium carbonate in the present invention can make the coating have excellent leveling and aging resistance, and calcium carbonate can improve the flame retardant performance of the coating, which is safe and pollution-free.

[0022] 6. The filler of the present invention has strong activity and high mutual affinity. The hydrophilic silica and the hydrophobic silica aerogel are dispersed with each other after high-speed stirring and mixing, and are attracted to the hydrophilic groups and hydrophobic groups of the other raw materials in the system, respectively, solving the problem that single silica is prone to agglomeration when the addition amount is high.

[0023] 7. The present invention modifies the hollow glass microspheres to improve the interfacial compatibility between the microspheres and the matrix film-forming agent, as well as other fillers and additives, promotes the penetration of silica and calcium carbonate whiskers into the gaps between the microspheres, reduces the effect of the hollow glass microspheres on the elongation at break, and reduces cracks in the coating.

[0024] 8. The preparation method of the present invention is simple, the coating prepared by the obtained coating has the functions of ultra-lightness and heat insulation, the raw materials are easy to obtain, and the production cost is low. DETAILED DESCRIPTION

[0025] Example 1: (1) 2 g of sodium dodecyl sulfate was prepared into a 6 g / L sodium dodecyl sulfate aqueous solution, 0.5 g of magnesium chloride was added while stirring, and after thorough mixing, a precursor solution was obtained.

[0026] (2) Take 1g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30-40°C for 3h; then add the magnesium chloride solution and react at 80°C for 6h; after filtering, wash the precipitate thoroughly to obtain calcium carbonate whiskers.

[0027] (3) The glass microspheres were placed in concentrated acetic acid with a volume ratio of acetic acid to water of 8:1 and stirred at a low speed for 18 h. Ethanol was added to dilute the pH of the system to 4, and 3-aminopropyltriethoxysilane was added in an amount 1.5 times the mass of the glass microspheres. After reacting for 24 h, the modified glass microspheres were rinsed and dried to obtain the modified glass microspheres.

[0028] (4) By weight, 3.5 parts of BYK-190 dispersant, 0.2 parts of CF-10 wetting agent and 1.5 parts of propylene glycol were fully dispersed in 50 parts of water, and 2.5 parts of hydrophilic silica and 3 parts of hydrophobic silica were added. After the addition was complete, the speed was increased from 100 r / min to 1200 r / min. After the raw materials were evenly mixed, 0.5 parts of 901W defoamer were added for defoaming. After defoaming, 40 parts of styrene acrylic emulsion and alcohol ester 12 were added to obtain a matrix slurry. At a speed of 300-600 r / min, 15 parts of hollow microspheres and 5 parts of

[0029] Calcium carbonate whiskers are obtained after complete dispersion.

[0030] Example 2: The difference from Example 1 is that:

[0031] (2) Take 1g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30-40°C for 1h; then add the magnesium chloride solution and react at 80°C for 6h; filter and thoroughly wash the precipitate to obtain calcium carbonate whiskers.

[0032] Example 3: The difference from Example 1 is that:

[0033] (2) Take 1g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30-40°C for 3h; then add the magnesium chloride solution and react at 80°C for 8h; after filtering, wash the precipitate thoroughly to obtain calcium carbonate whiskers.

[0034] Example 4: The difference from Example 1 is that:

[0035] (1) 2 g of sodium dodecyl sulfate was prepared into a 6 g / L sodium dodecyl sulfate aqueous solution, and 0.2 g of magnesium chloride was added while stirring. After thorough mixing, a precursor solution was obtained.

[0036] (2) Take 1.5g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30-40°C for 3h; then add the magnesium chloride solution and react at 80°C for 6h; after filtering, wash the precipitate thoroughly to obtain calcium carbonate whiskers.

[0037] Example 5: The difference from Example 1 is that:

[0038] (1) 2 g of sodium dodecyl sulfate was prepared into a 6 g / L sodium dodecyl sulfate aqueous solution, and 0.8 g of magnesium chloride was added while stirring. After thorough mixing, a precursor solution was obtained.

[0039] (2) Take 0.5g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30-40°C for 3h; then add the magnesium chloride solution and react at 80°C for 6h; after filtering, wash the precipitate thoroughly to obtain calcium carbonate whiskers.

[0040] Example 6: The difference from Example 1 is that:

[0041] (3) The glass microspheres were placed in concentrated acetic acid with a volume ratio of acetic acid to water of 2:1 and stirred at a low speed for 18 h. Ethanol was added to dilute the pH of the system to 4, and 3-aminopropyltriethoxysilane was added in an amount 1.5 times the mass of the glass microspheres. After reacting for 24 h, the modified glass microspheres were rinsed and dried to obtain the modified glass microspheres.

[0042] Example 7: The difference from Example 1 is that:

[0043] (4) By weight, 4 parts of BYK-190 dispersant, 0.2 parts of CF-10 wetting agent and 1.5 parts of propylene glycol were fully dispersed in 50 parts of water, and 2 parts of hydrophilic silica and 6 parts of hydrophobic silica were added. After complete addition, the rotation speed was increased from 100 r / min to 1200 r / min. After the raw materials were evenly mixed, 0.5 parts of 901W defoamer were added for defoaming. After defoaming, 40 parts of styrene acrylic emulsion and alcohol ester 12 were added to obtain a matrix slurry; 15 parts of hollow microspheres and 5 parts of calcium carbonate whiskers were added to the matrix slurry at a speed of 300-600 r / min, and the mixture was obtained after complete dispersion.

[0044] Example 8: The difference from Example 1 is that:

[0045] (4) By weight, 4 parts of BYK-190 dispersant, 0.2 parts of CF-10 wetting agent and 1.5 parts of propylene glycol were fully dispersed in 50 parts of water, and 4 parts of hydrophilic silica and 2 parts of hydrophobic silica were added. After complete addition, the rotation speed was increased from 100 r / min to 1200 r / min. After the raw materials were evenly mixed, 0.5 parts of 901W defoamer were added for defoaming. After defoaming, 40 parts of styrene acrylic emulsion and alcohol ester 12 were added to obtain a matrix slurry; 15 parts of hollow microspheres and 5 parts of calcium carbonate whiskers were added to the matrix slurry at a speed of 300-600 r / min, and the mixture was obtained after complete dispersion.

[0046] Example 9: The difference from Example 1 is that:

[0047] (4) By weight, 3.5 parts of BYK-190 dispersant, 0.2 parts of CF-10 wetting agent and 1.5 parts of propylene glycol were fully dispersed in 50 parts of water, and 3 parts of hydrophilic silica and 3 parts of hydrophobic silica were added. After the addition was complete, the speed was increased from 300 r / min to 1200 r / min. After the raw materials were evenly mixed, 0.5 parts of 901W defoamer were added for defoaming. After defoaming, 40 parts of styrene acrylic emulsion and alcohol ester 12 were added to obtain a matrix slurry. At a speed of 300-600 r / min, 15 parts of hollow microspheres and 5 parts of

[0048] Calcium carbonate whiskers are obtained after complete dispersion.

[0049] Example 10: The difference from Example 1 is that:

[0050] (4) By weight, 3.5 parts of BYK-190 dispersant, 0.2 parts of CF-10 wetting agent and 1.5 parts of propylene glycol were fully dispersed in 50 parts of water, and 2.5 parts of hydrophilic silica and 3 parts of hydrophobic silica were added. After the addition was complete, the speed was increased from 100 r / min to 1000 r / min. After the raw materials were evenly mixed, 0.5 parts of 901W defoamer was added for defoaming. After defoaming, 40 parts of styrene acrylic emulsion and alcohol ester 12 were added to obtain a matrix slurry. At a speed of 300-600 r / min, 15 parts of hollow microspheres and 5 parts of

[0051] Calcium carbonate whiskers are obtained after complete dispersion.

[0052] Example 11: The difference from Example 1 is that:

[0053] The glass microspheres were not modified.

[0054] Comparative Example 1: The difference from Example 1 is:

[0055] (1) 2 g of sodium dodecyl sulfate was prepared into a 6 g / L sodium dodecyl sulfate aqueous solution, and 1.5 g of magnesium chloride was added while stirring. After thorough mixing, a precursor solution was obtained.

[0056] (2) Prepare a suspension containing 1g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir to react at room temperature for 3h; then heat to 80℃ and react for 6h; filter and thoroughly wash the precipitate to obtain calcium carbonate whiskers.

[0057] Comparative Example 2: The difference from Example 1 is:

[0058] (1) Take 1.5g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1g of calcium hydroxide, add the calcium hydroxide suspension to the magnesium chloride solution, and react at 80°C for 1h; filter and thoroughly wash the precipitate to obtain calcium carbonate whiskers.

[0059] Comparative Example 3: The difference from Example 1 is:

[0060] No hydrophilic silica or hydrophobic silica is added.

[0061] Comparative Example 4: The difference from Example 1 is:

[0062] No calcium carbonate whiskers were added.

[0063] Example Sample Test: Bulk density of calcium carbonate whiskers obtained in Examples 1 to 5 and Comparative Examples 1 and 2. The results are as follows:

[0064]

[0065] Comparative Examples 1 to 5, as well as Comparative Examples 1 and 2, show that in the step of adding only part of the magnesium ions, a longer reaction time is beneficial to the formation of the hollow structure of calcium carbonate and the stability of the structure, and sodium lauryl sulfate is also the key to forming the hollow structure, so the bulk density of Example 2 is larger than that of Example 1, and the bulk density of Comparative Example 2 is the largest. The longer reaction time of Example 3 is beneficial to the growth of whiskers, and the bulk density decreases. The amount of magnesium ions added in the early stage of Example 4 is small, but its bulk density does not decrease as expected, which may be that too little magnesium is not conducive to the stable formation of the hollow structure of calcium carbonate in the early stage. The magnesium ions added in the early stage of Example 5 are more than those added in the later stage, but its bulk density also increases significantly, which may be that in the process of forming the hollow structure, more magnesium consumes more calcium ions, which is not conducive to the continued growth of whiskers in the later stage. Comparative Example 1 places magnesium chloride and sodium lauryl sulfate in the system for reaction, and the bulk density increases significantly, which may be due to the lack of the growth process of whiskers in the later stage.

[0066] The coatings prepared in the examples and comparative examples were tested for dry time, adhesion, stain resistance, bonding strength and thermal conductivity at a temperature of 23° C. and a humidity of 50%. The results are shown in the following table:

[0067]

[0068]

[0069] As can be seen from the table above, with the exception of Example 11, which achieved Level II adhesion, all other examples exhibited excellent dry-to-air time, adhesion, stain resistance, bond strength, and thermal conductivity. However, the bond strengths of Example 11 and Comparative Examples 1-4 were lower, and the adhesion of Comparative Examples 3 and 4 was inferior to that of the examples. This suggests that silica and calcium carbonate whiskers can help increase the adhesion between the glass microspheres and the base emulsion, maintaining the integrity of the coating and improving the adhesion and bond strength of the coating. Furthermore, while the adhesion of Example 11 approached the Level 1 threshold in actual testing, compared to the other examples with superior adhesion and bond strength, it is clear that modification of the glass microspheres is beneficial in improving the adhesion and bond strength of the coating.

[0070] The thermal conductivity of Examples 1 to 5 and Comparative Examples 1 and 2 is consistent with the bulk density. The thermal conductivity of Examples with low bulk density is also relatively low. Among them, the thermal conductivity of Examples 2, 4 and Comparative Example 2, which are not conducive to the formation of hollow structures, increases more significantly, indicating that the hollow structure significantly improves the thermal insulation performance of the coating. Example 7 has more hydrophobic silica, and Example 8 has more hydrophilic silica. The thermal conductivity of Example 7 is lower than that of Example 8, indicating that the increase in the relative content of hydrophobic silica is beneficial to improving the thermal insulation performance of the coating. Example 9 has a fast speed increase during the coating mixing process, and Example 10 has a slower speed. The thermal conductivity of both is higher than that of Example 1. It may be that the faster acceleration and lower stirring speed are not conducive to the full dispersion of silica. The thermal conductivity of Examples 6 and 11 does not change significantly compared to Example 1, indicating that the modification of the glass microspheres has no obvious effect on the thermal insulation performance, and the main impact is reflected in the mechanical properties of the coating.

[0071] Those skilled in the art can make various other corresponding changes and deformations based on the technical solutions and concepts described above, and all of these changes and deformations should fall within the scope of protection of the claims of the present invention.

Claims

1. An ultra-light thermal insulation coating, characterized in that: Calculated by mass, it includes 20-60 parts of styrene-acrylic emulsion, 10-20 parts of hollow microspheres, 2-4 parts of hydrophilic silica, 2-6 parts of hydrophobic silica, 2-7 parts of calcium carbonate whiskers and 2-6 parts of additives; The preparation of the calcium carbonate whisker comprises the following steps: a. Prepare a 6-15 g / L aqueous solution of sodium dodecyl sulfate, add a portion of magnesium chloride while stirring, and mix thoroughly to obtain a precursor solution. b. Prepare a magnesium chloride solution with the remaining magnesium chloride. Prepare a calcium hydroxide suspension, add the calcium hydroxide suspension to the precursor solution, and stir at 30-40°C for 1-3 hours. Then, add the magnesium chloride solution and react at 70-85°C for 4-8 hours. Filter and thoroughly wash the precipitate to obtain calcium carbonate whiskers. The mass ratio of the sodium lauryl sulfate in step a to the calcium hydroxide in step b is 1.5-2.5:1; the mass ratio of part of the magnesium chloride in step a to the calcium hydroxide in step b is 0.2-0.8:1; and the mass ratio of the remaining magnesium chloride in step b to the calcium hydroxide is 0.5-1.5:

1.

2. The ultra-lightweight thermal insulation coating according to claim 1, characterized in that: The auxiliary agents include dispersants, defoamers and wetting agents.

3. The ultra-lightweight thermal insulation coating according to claim 1, characterized in that: The calcined calcium oxide is added to water, the system is kept at a slight boil, and digested for 1 to 2 hours to obtain a calcium hydroxide suspension.

4. A method for preparing the ultra-lightweight thermal insulation coating according to claim 1 or 2, characterized in that: The additives are fully dispersed in water, and hydrophilic silica and hydrophobic silica are added. After complete addition, the rotation speed is increased to 1000-1500 r / min. After the raw materials are evenly mixed, defoaming is performed. After defoaming, a film-forming agent and a film-forming auxiliary are added to obtain a matrix slurry. Under medium-speed stirring, hollow microspheres and calcium carbonate whiskers are added to the matrix slurry and the mixture is obtained after complete dispersion.

5. The method for preparing the ultra-lightweight thermal insulation coating according to claim 4, characterized in that: Increase the speed by 100~300r / min per minute.

6. The method for preparing the ultra-lightweight thermal insulation coating according to claim 4, characterized in that: The hydrophobic silane coupling agent is used to modify the silicon dioxide to obtain hydrophobic silicon dioxide; the amino-containing silane coupling agent is used to modify the silicon dioxide to obtain hydrophilic silicon dioxide.

7. The method for preparing the ultra-lightweight thermal insulation coating according to claim 4, characterized in that: The hollow microspheres are glass microspheres. The glass microspheres are modified, comprising the following steps: placing the glass microspheres in concentrated acetic acid and stirring at a low speed for 12 to 24 hours; adding ethanol to dilute the pH of the system to 4 to 6, adding 3-aminopropyltriethoxysilane, reacting for 12 to 24 hours, rinsing, and drying to complete the modification.

8. The method for preparing the ultra-lightweight thermal insulation coating according to claim 7, characterized in that: The volume ratio of acetic acid to water in the concentrated acetic acid is 10-2:1; the mass ratio of the glass microspheres to 3-aminopropyltriethoxysilane is 1:1-2.

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