Ultra-light heat insulation coating and preparation method thereof

Abstract

The invention belongs to the field of coating preparation, and particularly relates to an ultra-light heat insulation coating and a preparation method thereof.The ultra-light heat insulation coating is prepared from, by mass, 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 auxiliaries. The preparation method disclosed by the invention is simple, the obtained ultra-light heat-insulating coating adopts the combination of fillers with various sizes and shapes, the phenomena of layering and non-uniform dispersion of the coating can be avoided, and the ultra-light heat-insulating coating has the effects of ultra-light weight and heat insulation.

Description

Technical Field

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

[0002] The energy consumption of air conditioning and heating accounts for the vast majority of building energy consumption. Using thermal insulation coatings on building walls is conducive to keeping the temperature inside the building within a comfortable temperature range, reducing the temperature loss of air conditioning and heating, and thus achieving the goal of energy saving. The coating applied on the vertical wall must ensure that it has a low density to prevent it from flowing and agglomerating. The components of thermal insulation coatings mainly include resins, pigments, additives and fillers. While the functional fillers play a filling role to reduce costs, they also need to take into account the role of light weight and reducing the thermal conductivity of the coating. For example, adding hollow microspheres, sepiolite, etc. can improve the thermal insulation effect of the coating. However, in order to ensure the integrity during the mixing process, the particle size and wall thickness of the hollow glass microspheres cannot be further reduced. The voids caused by the accumulation of particles will also affect the thermal insulation performance of the coating. Using only fillers of similar size and properties to glass microspheres will have limited effect on improving the thermal insulation performance of the coating. Summary of the invention

[0003] In order to solve the problem of limited thermal insulation performance of coatings using glass microspheres in the prior art, the present invention provides a thermal insulation coating that combines thermal insulation materials of various sizes and shapes, has strong affinity between raw materials, and is lightweight, and a preparation method of the coating. The technical solution is as follows:

[0004] An ultra-lightweight heat-insulating coating comprises, by weight, 20 to 60 parts of a film former, 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 method for preparing the above-mentioned ultra-lightweight thermal insulation coating comprises the following steps: fully dispersing the additive in water, adding hydrophilic silica and hydrophobic silica, and after complete addition, increasing the rotation speed to 1000-1500r / min, and after the raw materials are evenly mixed, defoaming is performed, and after defoaming, a film-forming agent and a film-forming additive are added to obtain a matrix slurry; hollow microspheres and calcium carbonate whiskers are added to the matrix slurry under medium-speed stirring, and the coating is obtained after complete dispersion.

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

[0008] Further, the preparation of the calcium carbonate whisker comprises the following steps:

[0009] a. Prepare an aqueous solution of sodium dodecyl sulfate and add part of magnesium chloride while stirring. After thorough mixing, a precursor solution is obtained;

[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; filter and 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; 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 digestion is performed for 1 to 2 hours to obtain a calcium hydroxide suspension.

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

[0014] Furthermore, the hollow microspheres are glass microspheres; the glass microspheres are modified, including 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, and the modification is completed.

[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 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 heat-insulating coating of the present invention uses a combination of fillers of various sizes and shapes to avoid the phenomenon of stratification and uneven dispersion of the coating. In addition, the calcium carbonate whiskers can improve the mechanical properties of the coating and reduce the probability of cracks 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 heat 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, thus 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 interface compatibility between the microspheres and the matrix film-forming agent, as well as other fillers and additives, promotes the penetration of silicon dioxide and calcium carbonate whiskers into the gaps between the microspheres, reduces the influence 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 obtained by the obtained paint has the effect of ultra-lightweight and heat insulation, the raw materials are easy to obtain, and the production cost is low. DETAILED DESCRIPTION

[0025] Example 1: (1) Take 2 g of sodium dodecyl sulfate and prepare a 6 g / L sodium dodecyl sulfate aqueous solution. Add 0.5 g of magnesium chloride while stirring. After thorough mixing, a precursor solution is 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; filter and thoroughly wash the precipitate to obtain calcium carbonate whiskers.

[0027] (3) The glass microspheres are 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 hours; ethanol is added to dilute the pH of the system to 4, and 3-aminopropyltriethoxysilane is added in an amount of 1.5 times the mass of the glass microspheres. After reacting for 24 hours, the modified glass microspheres are 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 was 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

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

[0030] Embodiment 2: The difference from Embodiment 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] Embodiment 3: The difference from Embodiment 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; filter and thoroughly wash the precipitate to obtain calcium carbonate whiskers.

[0034] Embodiment 4: The difference from Embodiment 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 1.5 g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1 g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30-40° C. for 3 h; then add the magnesium chloride solution and react at 80° C. for 6 h; filter and thoroughly wash the precipitate to obtain calcium carbonate whiskers.

[0037] Embodiment 5: The difference from Embodiment 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 0.5 g of magnesium chloride and prepare a magnesium chloride solution; prepare a suspension containing 1 g of calcium hydroxide, add the calcium hydroxide suspension to the precursor solution, and stir and react at 30 - 40 °C for 3 h; then add the magnesium chloride solution and react at 80 °C for 6 h; after filtration, wash the precipitate thoroughly to obtain calcium carbonate whiskers.

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

[0041] (3) Place the glass microspheres in concentrated acetic acid with a volume ratio of acetic acid to water of 2:1, and stir at a low speed for 18 h; add ethanol to dilute the pH of the system to 4, add 3-aminopropyltriethoxysilane which is 1.5 times the mass of the glass microspheres, after reacting for 24 h, rinse and dry to obtain the modified glass microspheres.

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

[0043] (4) By mass, disperse 4 parts of BYK-190 dispersant, 0.2 part of CF-10 wetting agent and 1.5 parts of propylene glycol in 50 parts of water, add 2 parts of hydrophilic silica and 6 parts of hydrophobic silica. After complete addition, increase the rotation speed to 1200 r / min at a speed of 100 r / min per minute. After the raw materials are mixed evenly, add 0.5 part of 901W defoaming agent for defoaming. After defoaming, add 40 parts of styrene-acrylic emulsion and alcohol ester 12 to obtain the matrix slurry; at a speed of 300 - 600 r / min, add 15 parts of hollow microspheres and 5 parts of calcium carbonate whiskers to the matrix slurry, and obtain the product after complete dispersion.

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

[0045] (4) By mass, disperse 4 parts of BYK-190 dispersant, 0.2 part of CF-10 wetting agent and 1.5 parts of propylene glycol in 50 parts of water, add 4 parts of hydrophilic silica and 2 parts of hydrophobic silica. After complete addition, increase the rotation speed to 1200 r / min at a speed of 100 r / min per minute. After the raw materials are mixed evenly, add 0.5 part of 901W defoaming agent for defoaming. After defoaming, add 40 parts of styrene-acrylic emulsion and alcohol ester 12 to obtain the matrix slurry; at a speed of 300 - 600 r / min, add 15 parts of hollow microspheres and 5 parts of calcium carbonate whiskers to the matrix slurry, and obtain the product 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 was 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

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

[0049] Embodiment 10: The difference from Embodiment 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; 15 parts of hollow microspheres and 5 parts of

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

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

[0053] The glass microspheres were not modified.

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

[0055] (1) Take 2 g of sodium dodecyl sulfate and prepare a 6 g / L sodium dodecyl sulfate aqueous solution. Add 1.5 g of magnesium chloride while stirring. After thorough mixing, a precursor solution is obtained.

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

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

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

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

[0060] Neither hydrophilic silica nor hydrophobic silica is added.

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

[0062] Calcium carbonate whiskers are not added.

[0063] Testing of Example samples: The bulk density of the calcium carbonate whiskers obtained in Examples 1 to 5 and Comparative Examples 1 and 2. The results are as follows:

[0064]

[0065] Comparing Examples 1 to 5 and Comparative Examples 1 and 2, it can be seen that in the step of adding only part of the magnesium ions, a longer reaction time is beneficial to the formation and structural stability of the hollow structure of calcium carbonate, and sodium dodecyl sulfate is also the key to forming the hollow structure. Therefore, the bulk density of Example 2 is greater than that of Example 1, and the bulk density of Comparative Example 2 is the largest. In Example 3, a longer reaction time is beneficial to the growth of whiskers, and the bulk density decreases. In Example 4, the amount of magnesium ions added in the early stage is small, but its bulk density does not decrease as expected. It may be that too little magnesium is not conducive to the stable formation of the hollow structure of calcium carbonate in the early stage. In Example 5, more magnesium ions are added in the early stage than in the later stage, but its bulk density also increases significantly. It may be that during the formation of the hollow structure, more magnesium consumes more calcium ions, which is not conducive to the continued growth of whiskers in the later stage. In Comparative Example 1, magnesium chloride and sodium dodecyl sulfate are reacted together in the system, and the bulk density increases significantly, probably due to the lack of the later whisker growth process.

[0066] The coatings prepared in each example and comparative example were tested for surface drying time, adhesion, stain resistance, bond strength, and thermal conductivity under the conditions of temperature 23 °C and humidity 50%. The results are shown in the following table:

[0067]

[0068]

[0069] As can be seen from the above table, except that the adhesion of Example 11 is Grade II, the surface drying time, adhesion, stain resistance, bond strength and thermal conductivity of each example are all very excellent. The bond strengths of Example 11 and Comparative Examples 1-4 are lower, and the adhesions of Comparative Example 3 and Comparative Example 4 are inferior to those of the examples, indicating that silica and calcium carbonate whiskers can be beneficial to increasing the adhesion between glass beads and the base emulsion, maintaining the integrity of the coating, and improving the adhesion and bond strength of the coating. Moreover, the adhesion of Example 11 is close to the boundary value of Grade 1 in actual tests. However, compared with the other examples with better adhesion and bond strength, it can be found that the modification of glass beads is beneficial to improving the adhesion and bond strength of the coating.

[0070] The thermal conductivities and bulk densities of Examples 1-5, Comparative Example 1 and Comparative Example 2 are compatible. The thermal conductivities of the examples with lower bulk densities are also relatively lower. Among them, the increase in the thermal conductivities of Examples 2 and 4 and Comparative Example 2, which are not conducive to the formation of the hollow structure, is more obvious, indicating that the hollow structure has an obvious effect on improving the heat 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 heat insulation performance of the coating. The rotational speed of Example 9 increases rapidly during the coating mixing process, and the rotational speed of Example 10 is slower. The thermal conductivities of both are higher than that of Example 1. It may be that faster acceleration and lower stirring speed are not conducive to the full dispersion of silica. The changes in the thermal conductivities of Examples 6 and 11 compared with Example 1 are not obvious, indicating that the modification of glass beads has no obvious effect on the heat insulation performance, and the main effect is reflected in the mechanical properties of the coating.

[0071] For those skilled in the art, various corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all such changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. An ultra-lightweight thermal insulation coating, characterized in that: The invention comprises, by weight, 20 to 60 parts of 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 auxiliary agents.

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

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

4. The method for preparing the ultra-lightweight thermal insulation coating according to claim 3, characterized in that: Increase the speed by 100 to 300 r / min per minute.

5. The method for preparing the ultra-lightweight thermal insulation coating according to claim 3, characterized in that: The preparation of the calcium carbonate whisker comprises the following steps: a. Prepare an aqueous solution of sodium dodecyl sulfate and add part of magnesium chloride while stirring. After thorough mixing, a precursor solution is obtained; 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; filter and wash the precipitate thoroughly to obtain calcium carbonate whiskers.

6. The method for preparing the ultra-lightweight thermal insulation coating according to claim 5, characterized in that: 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; the mass ratio of the remaining magnesium chloride in step b to calcium hydroxide is 0.5 to 1.5:

1.

7. The method for preparing the ultra-lightweight thermal insulation coating according to claim 5, characterized in that: The calcium oxide obtained by calcination is added to water, the system is kept at a slight boil, and digestion is carried out for 1 to 2 hours to obtain a calcium hydroxide suspension.

8. The method for preparing the ultra-lightweight thermal insulation coating according to claim 3, characterized in that: The hydrophobic silane coupling agent is used to modify the silicon dioxide to obtain the hydrophobic silicon dioxide; the amino-containing silane coupling agent is used to modify the silicon dioxide to obtain the hydrophilic silicon dioxide.

9. The method for preparing the ultra-lightweight thermal insulation coating according to claim 1, characterized in that: The hollow microspheres are glass microspheres. The glass microspheres are modified, including 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, and the modification is completed.

10. The method for preparing the ultra-lightweight thermal insulation coating according to claim 9, 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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