One-component silicone sealant for glass curtain wall and preparation method thereof

Abstract

The present invention discloses a one-component silicone sealant for glass curtain wall and a preparation method thereof, and belongs to the technical field of adhesives. The one-component silicone sealant for glass curtain wall comprises the following components: by weight, 80-100 parts of α, ω-dihydroxy polydimethylsiloxane, 5-20 parts of silicone oil plasticizer, 10-20 parts of nano calcium carbonate, 3-5 parts of modified hollow fiber, 0.5-5 parts of pressure-sensitive nano sepiolite microcapsules, 0.5-1.5 parts of porous starch microcapsules, 0.05-0.1 parts of catalysts and 0.5-5 parts of cross-linking agents. The one-component silicone sealant of the present invention has a simple method of use, fast curing speed, short required curing time, can speed up the construction process, has good bonding performance, high tensile strength at break, and reduces the cracking rate of the adhesive layer.

Description

Technical Field

[0001] The invention relates to a single-component silicone sealant for a glass curtain wall and a preparation method thereof, belonging to the technical field of adhesives. Background Art

[0002] Glass curtain walls play a vital role in modern buildings. They not only protect the interior of the building from bad weather and other external factors, but also have functions such as heat insulation, sound insulation and fire protection. Therefore, in order to ensure the integrity of the building's appearance and structure, the adhesive used when pasting glass curtain walls is crucial, and silicone sealants are usually used.

[0003] Silicone sealant refers to a sealant produced with linear polysiloxane as the main raw material, also known as organosilicon sealant. It is a kind of organosilicon product that is widely used and promoted in the construction industry. The one-component silicone sealant is simple to use and is generally used for on-site construction. However, the one-component silicone sealant absorbs moisture in the air to hydrolyze, and gradually solidifies from the surface to the deep layer. The curing speed is relatively slow. There are certain requirements for the depth, width, ambient temperature and humidity of the glue. Under normal circumstances, the sealant has a certain strength 5-7 days after construction, and it usually takes 21 days to fully cure. The slow curing speed and long time affect the construction progress. Summary of the invention

[0004] In view of the deficiencies of the prior art, the object of the present invention is to provide a one-component silicone sealant for glass curtain walls and a preparation method thereof, which can accelerate the curing speed of the silicone sealant and improve the bonding performance of the silicone sealant.

[0005] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0006] A single-component silicone sealant for glass curtain walls comprises the following components: by weight, 80-100 parts of α,ω-dihydroxy polydimethylsiloxane, 5-20 parts of silicone oil plasticizer, 10-20 parts of nano calcium carbonate, 3-5 parts of modified hollow fibers, 0.5-5 parts of pressure-sensitive nano sepiolite microcapsules, 0.5-1.5 parts of porous starch microcapsules, 0.05-0.1 parts of catalysts and 0.5-5 parts of crosslinking agents.

[0007] Furthermore, the preparation method of the modified hollow fiber is: breaking and grinding the hollow fiber into fine particles, and subjecting the particles to atmospheric plasma treatment. The atmospheric plasma treatment can introduce nitrogen and oxygen in the air into the fiber surface in the form of hydroxyl, carboxyl, and amino groups, which can react with the components of the silicone sealant and improve the bonding force with the wall and curtain wall. When the external temperature changes greatly, the hollow fiber has a warming effect, so that the temperature of the silicone sealant does not change much, the original strength and elasticity can be maintained, and the cracking of the adhesive layer can be avoided.

[0008] Furthermore, the conditions of the atmospheric plasma treatment are: equipment power is 800-1000w, and the processing speed is 15mm / s.

[0009] Furthermore, the preparation method of the pressure-sensitive nano-sepiolite microcapsules is:

[0010] (1) Mix nano sepiolite with a concentration of 1.0-1.5 mol·L -1 and hydrochloric acid, stirred in vacuum for 20-30 minutes, then filtered, washed, and dried at 110-120°C to obtain acidified nano-sepiolite;

[0011] (2) Melamine and formaldehyde are reacted under alkaline conditions to form a prepolymer, and then the acidified nano-sepiolite is emulsified at 25-30°C to form an emulsion. Finally, the prepolymer is adjusted to a pH of 5.0-5.5 with acrylic acid, mixed with the emulsion for 15-20 minutes, filtered, and dried to obtain pressure-sensitive nano-sepiolite microcapsules.

[0012] Furthermore, the acidification conditions after the nano-sepiolite and hydrochloric acid are mixed are: acidification at 90-100° C. for 6-8 hours. The moisture absorption and desorption capacity and moisture absorption and desorption speed of the acidified sepiolite are increased.

[0013] Furthermore, the mass concentration of the acrylic acid is 8-10%. At this time, the wall material has moderate strength, and the wall material breaks after extrusion, and the acidified nano-sepiolite is exposed. If the concentration of acrylic acid is large and the amount added when adjusting the pH is small, the system cannot be polymerized into a strong pressure-resistant wall material, and it is easy to break in the subsequent process of preparing silicone sealant; while if the concentration of acrylic acid is small and the amount added when adjusting the pH is large, the system can be polymerized into a strong pressure-resistant wall material, and the wall material is not easy to break in the subsequent process of extruding the silicone sealant, and the acidified nano-sepiolite cannot be exposed.

[0014] Furthermore, the water content of the acidified nano-sepiolite in the pressure-sensitive nano-sepiolite microcapsules is 0.05-0.10%.

[0015] The surface of the silicone sealant is in contact with moisture in the air and solidifies, while the silicone sealant inside cannot be exposed to air and solidifies slowly. Sepiolite has many pores and a large specific surface area inside that can adsorb water molecules. In a dry environment, it can also desorb water molecules. After the silicone sealant is squeezed out of the tube, it contacts the curtain wall, the wall material breaks, and contacts the curtain wall. Due to the low moisture content in the surrounding environment, the moisture absorbed by the sepiolite will gradually be released, accelerating the solidification of the internal silicone sealant, solving the problem of slow solidification of silicone sealant. Moreover, when the air humidity is high, nano sepiolite can also absorb moisture in the air, reduce the surface drying time, and accelerate the solidification rate.

[0016] Furthermore, the preparation method of the porous starch microcapsules is:

[0017] (1) Mix the chitosan solution and the calcium chloride solution, adjust the pH value to 3-4 with NaHCO3, and stir under vacuum at a speed of 350-450 r / min to obtain a mixed solution;

[0018] (2) Slowly drip the sodium alginate solution and porous starch solution into the mixed solution, slowly stir under vacuum, let stand for 20-25 minutes, filter and wash, wash the separated capsule particles with water, and then vacuum dry to obtain microcapsule products.

[0019] Since silicone sealant is highly hydrophobic and hygroscopic, it is easy to absorb surrounding moisture. During processing and use, moisture may be generated to decompose low-molecular organic matter, causing oil on the surface of silicone sealant. Porous starch is coated with microcapsules. After external aging, the wall material breaks and the porous starch leaks out, which can absorb the oily dialysis produced by silicone sealant, ensuring the quality of silicone sealant and increasing the bonding performance of silicone sealant. In addition, the wall material is chitosan and sodium alginate, which can enhance the tensile strength and plasticity of silicone sealant.

[0020] Furthermore, the concentration of the sodium alginate solution is 0.02-0.05 g / mL, and the concentration of the calcium chloride solution is 0.04-0.06 g / mL.

[0021] Furthermore, the concentration of the chitosan solution is 0.005-0.015 g / mL.

[0022] Furthermore, the crosslinking agent is a mixture of methyl-containing ketoxime silane, vinyl-containing ketoxime silane and phenyl-containing ketoxime silane in a mass ratio of 90-105:35-45:25-35.

[0023] Furthermore, the preparation method of the one-component silicone sealant for glass curtain wall comprises the following steps:

[0024] (1) Add α,ω-dihydroxy polydimethylsiloxane, silicone oil plasticizer, nano calcium carbonate, modified hollow fiber, pressure-sensitive nano sepiolite microcapsules, and porous starch microcapsules into a vacuum mixer and stir at 100-130° C. for 30-60 min;

[0025] (2) Add a catalyst and a cross-linking agent, stir under vacuum at 100-120°C for 30-60 minutes, and finally cool to 30-45°C to obtain a single-component silicone sealant for glass curtain walls.

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

[0027] (1) The one-component silicone sealant of the present invention is simple to use, has a fast curing speed, and requires a short curing time, which can speed up the construction process. It also has good bonding performance, high tensile strength at break, and reduces the cracking rate of the adhesive layer.

[0028] (2) The present invention adds modified hollow fibers to improve the bonding strength with the wall and curtain wall. When the external temperature changes greatly, the hollow fibers have a warming effect, which makes the temperature of the silicone sealant change little, and can maintain the original strength and elasticity, and can also avoid cracking of the adhesive layer.

[0029] (3) The present invention adds pressure-sensitive nano-sepiolite microcapsules, which contain acidified nano-sepiolite with a moisture content of 0.05-0.10%. The microcapsules can absorb moisture from the air, reduce the surface drying time, and accelerate the curing rate. In a dry environment, due to the low moisture content in the surrounding environment, the moisture absorbed by the sepiolite will be gradually released, accelerating the curing of the internal silicone sealant, thereby solving the problem of slow curing of the silicone sealant.

[0030] (4) The porous starch microcapsules added in the present invention, after external aging, the wall material of the microcapsules breaks, and the porous starch leaks out, which can absorb the oily exudates produced by the silicone sealant, thereby ensuring the quality of the silicone sealant and increasing the adhesion of the silicone sealant. At the same time, the wall material is chitosan and sodium alginate, which can enhance the tensile strength and plasticity of the silicone sealant. DETAILED DESCRIPTION

[0031] Example 1

[0032] A single-component silicone sealant for glass curtain walls comprises the following components: by weight, 80 parts of α,ω-dihydroxy polydimethylsiloxane, 5 parts of silicone oil plasticizer, 10 parts of nano calcium carbonate, 3 parts of modified hollow fibers, 0.5 parts of pressure-sensitive nano sepiolite microcapsules, 0.5 parts of porous starch microcapsules, 0.05 parts of catalysts and 0.5 parts of cross-linking agents.

[0033] The preparation method of the one-component silicone sealant for glass curtain wall is as follows:

[0034] (1) Add α,ω-dihydroxypolydimethylsiloxane, silicone oil plasticizer, nano calcium carbonate, modified hollow fiber, pressure-sensitive nano sepiolite microcapsules, and porous starch microcapsules into a vacuum mixer and stir at 100°C for 60 min;

[0035] (2) Add a catalyst and a cross-linking agent, stir under vacuum at 120°C for 30 minutes, and finally cool to 30°C to obtain a one-component silicone sealant for glass curtain walls.

[0036] Example 2

[0037] A single-component silicone sealant for glass curtain walls comprises the following components: by weight, 100 parts of α,ω-dihydroxy polydimethylsiloxane, 20 parts of silicone oil plasticizer, 20 parts of nano calcium carbonate, 5 parts of modified hollow fibers, 5 parts of pressure-sensitive nano sepiolite microcapsules, 1.5 parts of porous starch microcapsules, 0.1 parts of a catalyst and 5 parts of a cross-linking agent.

[0038] The preparation method of the one-component silicone sealant for glass curtain wall is as follows:

[0039] (1) Add α,ω-dihydroxypolydimethylsiloxane, silicone oil plasticizer, nano calcium carbonate, modified hollow fiber, pressure-sensitive nano sepiolite microcapsules, and porous starch microcapsules into a vacuum mixer and stir at 130°C for 60 min;

[0040] (2) Add a catalyst and a cross-linking agent, stir under vacuum at 100°C for 30 minutes, and finally cool to 45°C to obtain a one-component silicone sealant for glass curtain walls.

[0041] Example 3

[0042] A single-component silicone sealant for glass curtain walls comprises the following components: by weight, 90 parts of α,ω-dihydroxy polydimethylsiloxane, 15 parts of silicone oil plasticizer, 15 parts of nano calcium carbonate, 4 parts of modified hollow fibers, 2.5 parts of pressure-sensitive nano sepiolite microcapsules, 1.0 parts of porous starch microcapsules, 0.05 parts of catalysts and 2.5 parts of cross-linking agents.

[0043] The preparation method of the one-component silicone sealant for glass curtain wall is as follows:

[0044] (1) Add α,ω-dihydroxypolydimethylsiloxane, silicone oil plasticizer, nano calcium carbonate, modified hollow fiber, pressure-sensitive nano sepiolite microcapsules, and porous starch microcapsules into a vacuum mixer and stir at 115°C for 45 minutes;

[0045] (2) Add a catalyst and a cross-linking agent, stir under vacuum at 110°C for 45 minutes, and finally cool to 35°C to obtain a one-component silicone sealant for glass curtain walls.

[0046] Example 4

[0047] A single-component silicone sealant for glass curtain walls comprises the following components: by weight, 80 parts of α,ω-dihydroxy polydimethylsiloxane, 20 parts of silicone oil plasticizer, 10 parts of nano calcium carbonate, 5 parts of modified hollow fibers, 0.5 parts of pressure-sensitive nano sepiolite microcapsules, 1.5 parts of porous starch microcapsules, 0.05 parts of catalysts and 5 parts of cross-linking agents.

[0048] The preparation method of the one-component silicone sealant for glass curtain wall is as follows:

[0049] (1) Add α,ω-dihydroxypolydimethylsiloxane, silicone oil plasticizer, nano calcium carbonate, modified hollow fiber, pressure-sensitive nano sepiolite microcapsules, and porous starch microcapsules into a vacuum mixer and stir at 100°C for 30 min;

[0050] (2) Add a catalyst and a cross-linking agent, stir under vacuum at 120°C for 60 minutes, and finally cool to 30°C to obtain a one-component silicone sealant for glass curtain walls.

[0051] Comparative Example 1

[0052] No modified hollow fiber was added, and other steps were the same as in Example 3.

[0053] Comparative Example 2

[0054] The other steps are the same as those in Example 3 except that the pressure-sensitive nano-sepiolite microcapsules are not added.

[0055] Comparative Example 3

[0056] Without adding porous starch microcapsules, the other steps were the same as those in Example 3.

[0057] Comparative Example 4

[0058] The modified hollow fiber was replaced by the hollow fiber, and the rest was the same as in Example 3.

[0059] Comparative Example 5

[0060] The pressure-sensitive nano-sepiolite microcapsules were replaced with acidified nano-sepiolite, and the rest was the same as in Example 3.

[0061] Comparative Example 6

[0062] The pressure-sensitive nano-sepiolite microcapsules were replaced by nano-sepiolite, and the rest was the same as in Example 3.

[0063] Comparative Example 7

[0064] The porous starch microcapsules were replaced by porous starch, and the rest were the same as in Example 3.

[0065] Experimental Example 1

[0066] The properties of the silicone sealants of Examples 1 to 4 were measured in accordance with GB / T16776-2005 "Silicone structural sealants for construction".

[0067] The deep curing rate uses a wedge-shaped groove made of silicone non-stick material, and starts to inject adhesive from the lowest point of the groove to fill it evenly and without voids. Use a scraper to remove excess glue on the groove surface to ensure that the glue surface is flat and free of defects. Place it in a constant temperature room at 25℃ and 55%RH. After 24 hours, start from the highest point of the groove and lift the sealant until you see uncured adhesive attached to the wedge-shaped groove. Measure the thickness of the cured adhesive strip and use this thickness to characterize the deep curing rate.

[0068] The test results are listed in Table 1.

[0069] Table 1. Properties of silicone sealants

[0070]

[0071] As can be seen from Table 1, the silicone sealants of Examples 1-4 have excellent tensile bonding properties and heat aging resistance, and all the properties are relatively excellent. They have short surface drying time, fast curing speed, good bonding performance, high elongation at break, good tensile resistance, and are not easy to break. In addition, it was found in the test that the internal curing speed of the silicone sealant is also fast, the time required for complete curing is short, and the method of use is simple and convenient, which is conducive to speeding up the construction speed.

[0072] Experimental Example 2

[0073] According to GB / T16776-2005 "Silicone structural sealants for construction", the properties of the silicone sealants of Example 3, Comparative Example 1 and Comparative Example 4 were tested. The test results are listed in Table 2.

[0074] Table 2. Properties of silicone sealants

[0075]

[0076] As can be seen from Table 2, in Comparative Example 1, no modified hollow fibers were added, and the prepared silicone sealant had low bonding strength, poor bonding performance, and poor tensile strength of the adhesive layer. In Comparative Example 4, the various properties of the silicone sealant prepared by adding hollow fibers were slightly better than those of Comparative Example 1, but still worse than those of Example 3, indicating that the addition of modified hollow fibers can improve the bonding strength, and can also maintain the original strength and elasticity of the silicone sealant when the external temperature changes greatly.

[0077] Experimental Example 3

[0078] The properties of the silicone sealants of Example 3, Comparative Example 2 and Comparative Examples 6-7 were tested in accordance with GB / T16776-2005 "Silicone Structural Sealant for Construction". The test results are listed in Table 3.

[0079] Table 3. Properties of silicone sealants

[0080]

[0081] As shown in Table 3, the silicone sealant prepared in Comparative Example 2 without adding pressure-sensitive nano-sepiolite microcapsules has the longest surface drying time, the silicone sealant prepared in Comparative Example 5 with adding acidified nano-sepiolite has the shortest surface drying time, and the silicone sealant prepared in Comparative Example 6 with adding nano-sepiolite is between the two. However, the surface drying time of the above comparative examples is longer than that of Example 3, and the curing speed, bonding strength, etc. are all lower than those of Example 3, indicating that the addition of pressure-sensitive nano-sepiolite microcapsules can accelerate the curing speed, improve the bonding performance, and have a positive effect on the mechanical properties of the sealant. However, the silicone sealant prepared in Comparative Example 5 with adding acidified nano-sepiolite will cure prematurely because the acidified nano-sepiolite contains water, so it needs to be coated with microcapsules.

[0082] Experimental Example 4

[0083] The properties of the silicone sealants of Example 3 and Comparative Examples 1-3 were tested in accordance with GB / T16776-2005 "Silicone Structural Sealant for Construction". The test results are listed in Table 4.

[0084] Table 4. Properties of silicone sealants

[0085]

[0086] As can be seen from Table 4, in Comparative Example 3, porous starch microcapsules were not added, and the prepared silicone sealant had poor tensile strength and poor bonding properties. The bonding properties of the silicone sealant prepared in Comparative Example 7 by adding porous starch were better than those in Comparative Example 3, but worse than those in Example 3, indicating that the addition of porous starch can increase the bonding properties of the silicone sealant, and the addition of chitosan and sodium alginate as wall materials can enhance the tensile strength and plasticity of the silicone sealant.

[0087] It can be seen that the addition of modified hollow fibers, pressure-sensitive nano-sepiolite microcapsules and porous starch microcapsules in the present invention can improve the comprehensive properties of the silicone sealant, reduce its curing time and enhance its tensile strength.

Claims

1. A one-component silicone sealant for glass curtain wall, characterized in that: The invention comprises the following components: by weight, 80-100 parts of α,ω-dihydroxy polydimethylsiloxane, 5-20 parts of silicone oil plasticizer, 10-20 parts of nano calcium carbonate, 3-5 parts of modified hollow fiber, 0.5-5 parts of pressure-sensitive nano sepiolite microcapsules, 0.5-1.5 parts of porous starch microcapsules, 0.05-0.1 parts of catalyst and 0.5-5 parts of cross-linking agent; The modified hollow fiber is prepared by breaking and grinding the hollow fiber into fine particles, and treating the particles with atmospheric plasma; The preparation method of the pressure-sensitive nano-sepiolite microcapsule is as follows: (1) Mix nano sepiolite with a concentration of 1.0-1.5 mol·L -1 and hydrochloric acid, stirred in vacuum for 20-30 minutes, then filtered, washed, and dried at 110-120°C to obtain acidified nano-sepiolite; (2) Melamine and formaldehyde are reacted under alkaline conditions to form a prepolymer, and then the acidified nano-sepiolite is emulsified at 25-30°C to form an emulsion. Finally, the prepolymer is adjusted to a pH of 5.0-5.5 with acrylic acid, mixed with the emulsion for 15-20 minutes, filtered, and dried to obtain pressure-sensitive nano-sepiolite microcapsules; The preparation method of the porous starch microcapsule is: (1) Mix the chitosan solution and the calcium chloride solution, adjust the pH value to 3-4 with NaHCO3, and stir under vacuum at a speed of 350-450 r / min to obtain a mixed solution; (2) Slowly drip the sodium alginate solution and porous starch solution into the mixed solution, slowly stir under vacuum, let stand for 20-25 minutes, filter and wash, wash the separated capsule particles with water, and then vacuum dry to obtain microcapsule products.

2. The one-component silicone sealant for glass curtain wall according to claim 1, characterized in that: The conditions of the atmospheric plasma treatment are: equipment power is 800-1000w, and the treatment speed is 15mm / s.

3. The one-component silicone sealant for glass curtain wall according to claim 1, characterized in that: In step (1), the acidification conditions after the nano-sepiolite and hydrochloric acid are mixed are: acidification at 90-100° C. for 6-8 hours.

4. The one-component silicone sealant for glass curtain wall according to claim 1, characterized in that: In step (2), the mass concentration of acrylic acid is 8-10%.

5. The one-component silicone sealant for glass curtain wall according to claim 1, characterized in that: In step (2), the moisture content of the acidified nano-sepiolite in the pressure-sensitive nano-sepiolite microcapsules is 0.05-0.10%.

6. The one-component silicone sealant for glass curtain wall according to claim 1, characterized in that: The crosslinking agent is a mixture of methyl-containing ketoxime silane, vinyl-containing ketoxime silane and phenyl-containing ketoxime silane in a mass ratio of 90-105:35-45:25-35.

7. A method for preparing the one-component silicone sealant for glass curtain wall according to claim 1, characterized in that: The steps include: (1) Add α,ω-dihydroxy polydimethylsiloxane, silicone oil plasticizer, nano calcium carbonate, modified hollow fiber, pressure-sensitive nano sepiolite microcapsules, and porous starch microcapsules into a vacuum mixer and stir at 100-130° C. for 30-60 min; (2) Add a catalyst and a cross-linking agent, stir under vacuum at 100°C-120°C for 30-60 minutes, and finally cool to 30-45°C to obtain a single-component silicone sealant for glass curtain walls.

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