A method for modifying glass microspheres

Abstract

This invention relates to a method for modifying glass microspheres, belonging to the field of glass microsphere modification. The modification method includes the following steps: mixing glass microspheres with hot air and introducing the mixture into an airflow drying pipeline for airflow drying; during airflow drying, spraying a silanizing modifier and water sequentially onto the glass microspheres; obtaining glass microsphere powder from the outlet of the airflow drying pipeline; and then curing to obtain modified glass microspheres. This invention employs a combination of dry and wet methods to modify glass microspheres. The dry method involves spraying the silanizing modifier onto the surface of the glass microspheres in a hot air environment, while the wet method involves spraying water to moisten the surface of the glass microspheres coated with the silanizing modifier and induce modification. Finally, the modified glass microspheres are dried again with hot air to become powder and directly discharged without additional dehydration and drying. This method has high utilization efficiency of the silanizing modifier, is simple to operate, and is easy to scale up for industrial production.

Description

Technical Field

[0001] This invention relates to a method for modifying glass microspheres, belonging to the field of glass microsphere modification. Background Technology

[0002] Hollow glass microspheres are widely used in industries such as plastics, adhesives, rubber, and coatings. However, since glass microspheres are inorganic materials, their interfacial bonding with some organic materials is relatively poor. In order to optimize the overall performance of the material after adding glass microspheres, surface modification treatment is generally required before use. Currently, common modification schemes include dry and wet methods.

[0003] In wet modification, the modifier does not easily adhere to the powder surface in the liquid environment, resulting in a large amount of modifier being dispersed in the liquid and unable to function. Therefore, a large amount of modifier needs to be added to achieve a good effect, resulting in low utilization efficiency. Furthermore, since the modifier can react in the liquid phase, the modification effect can vary significantly if the process control is not precise. Wet modification also generates a large amount of wastewater, which can easily cause pollution. The common dry method involves mixing the powder and modifier uniformly under high-speed stirring conditions; however, this method easily causes the glass microspheres to break, making it unsuitable for modifying glass microspheres. Summary of the Invention

[0004] The purpose of this invention is to provide a method for modifying glass microspheres to solve the problem of low utilization efficiency of modifiers in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for modifying glass microspheres includes the following steps: mixing glass microspheres with hot air and introducing them into an airflow drying pipeline for airflow drying; spraying a silanizing modifier and water onto the glass microspheres sequentially during airflow drying; obtaining glass microsphere powder from the outlet of the airflow drying pipeline; and then curing to obtain modified glass microspheres.

[0007] This invention employs a combination of dry and wet methods to modify glass microspheres. The dry method involves spraying a silanizing modifier onto the surface of the glass microspheres in a hot air environment, while the wet method involves spraying water to wet the surface of the glass microspheres coated with the silanizing modifier and induce modification. Finally, the modified glass microspheres are dried again with hot air into powder and discharged directly, without the need for additional dehydration and drying. Moreover, the method of this invention is less prone to adhesion during the spraying of the modifier, and it is easier to spray evenly.

[0008] This method has a high utilization rate of silanization modifiers, is simple to operate, and is easy to mass-produce in factories.

[0009] To ensure uniform spraying of the silanizing modifier onto the surface of the glass microspheres, preferably, the silanizing modifier is sprayed at least twice.

[0010] To improve the quality of modified glass microspheres, preferably, the mass ratio of the silanizing modifier, water, and glass microspheres is (8-17):(2-5)2:1000.

[0011] Preferably, the silanizing modifier is sprayed three times, with the mass ratio of the first, second, and third sprays of the silanizing modifier, and the mass ratio of water to glass microspheres being (4-6):(2-6):(1-5):(2-5):1000. This multiple, small-volume spraying of the silanizing coupling agent ensures that the surface of the glass microspheres is completely covered and coated with the silanizing modifier, improving the modification effect.

[0012] To facilitate the operation of the modification method, preferably, at least one silanizing agent nozzle and a water nozzle are installed in the airflow drying pipeline along its length, and the silanizing agent and water are sprayed sequentially through the silanizing agent nozzle and the water nozzle.

[0013] To improve the modification effect of glass microspheres, preferably, the silanizing modifier is one or more of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane. The modification principles of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane are the same; therefore, adding them simultaneously can achieve the same effect.

[0014] Preferably, the temperature of the hot air is 110–125°C, and the air velocity is 10–13 m / s. This temperature is also the temperature at which the silanizing modifier is applied. This hot air temperature promotes the modification process, and the air velocity controls the tumbling of the glass microspheres in the airflow drying pipeline and the rate of modification.

[0015] To make the modification more complete and thorough, preferably, the curing temperature is 25-30℃ and the time is 26-28h. Detailed Implementation

[0016] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0017] I. Specific embodiments of the modification method for glass microspheres of the present invention are as follows:

[0018] Example 1

[0019] The method for modifying glass microspheres in this embodiment involves modifying an airflow dryer by installing silanizing agent nozzles and water nozzles along the length of the airflow drying pipeline. The silanizing agent and water are sprayed sequentially to modify the glass microspheres.

[0020] The specific steps are as follows: Glass microspheres (HL38) and hot air are mixed and introduced into the airflow drying pipeline for airflow drying. The flow rate of the hot air is set to 13 m / s and the temperature is set to 110℃. During the airflow drying, the glass microspheres are first sprayed with aminopropyltrimethoxysilane three times in sequence, and finally water is sprayed. The mass ratio of the first aminopropyltrimethoxysilane, the second aminopropyltrimethoxysilane, the third aminopropyltrimethoxysilane, water and glass microspheres is 5:2:1:2:1000. After the glass microspheres run in the airflow drying pipeline for 3 seconds, glass microsphere powder is obtained. Then, it is cured at 28℃ for 24 hours to obtain modified glass microspheres.

[0021] Example 2

[0022] The modification method of glass microspheres in this embodiment adopts the following steps: glass microspheres (HL32) and hot air are mixed and introduced into the airflow drying pipeline for airflow drying. The flow rate of the hot air is set to 10 m / s and the temperature is set to 115°C. During the airflow drying, the glass microspheres are first sprayed with aminopropyltriethoxysilane three times in sequence, and finally water is sprayed. The mass ratio of the first aminopropyltriethoxysilane, the second aminopropyltriethoxysilane, the third aminopropyltriethoxysilane, water and glass microspheres is 4:5:3:3:1000. After the glass microspheres run in the airflow drying pipeline for 4 seconds, glass microsphere powder is obtained. Then, it is cured at 30°C for 25 hours to obtain modified glass microspheres.

[0023] Example 3

[0024] The modification method of glass microspheres in this embodiment adopts the following steps: glass microspheres (HS38) and hot air are mixed and introduced into the airflow drying pipeline for airflow drying. The flow rate of the hot air is set to 11 m / s and the temperature is set to 125°C. During the airflow drying, the glass microspheres are first sprayed with vinyltrimethoxysilane three times in sequence, and finally sprayed with water. The mass ratio of the first vinyltrimethoxysilane, the second vinyltrimethoxysilane, the third vinyltrimethoxysilane, water and glass microspheres is 6:6:5:5:1000. After the glass microspheres run in the airflow drying pipeline for 4 seconds, glass microsphere powder is obtained. Then, it is cured at 25°C for 26 hours to obtain modified glass microspheres.

[0025] In other implementations, replacing vinyltrimethoxysilane with vinyltriethoxysilane yields modified glass microspheres with comparable properties.

[0026] II. Comparative Example

[0027] Comparative Example 1

[0028] The modification method of the glass microspheres in this comparative example adopts the following steps: glass microspheres (HL38) are mixed with deionized water and aminopropyltrimethoxysilane at a weight ratio of 1000:5000:5 at 40°C until homogeneous. After stirring for 1 hour, the mixture is dehydrated and dried to obtain the modified glass microspheres.

[0029] Comparative Example 2

[0030] The modification method of the glass microspheres in this comparative example adopts the following steps: glass microspheres (HS38) and hot air are mixed and introduced into the airflow drying pipeline for airflow drying. The flow rate of the hot air is set to 11 m / s and the temperature is set to 125℃. During the airflow drying, the glass microspheres are first sprayed with vinyltrimethoxysilane three times in sequence, and finally sprayed with alcohol. The mass ratio of the first vinyltrimethoxysilane, the second vinyltrimethoxysilane, the third vinyltrimethoxysilane, alcohol and glass microspheres is 6:6:5:5:1000. After the glass microspheres run in the airflow drying pipeline for 4 seconds, glass microsphere powder is obtained. Then, it is cured at 25℃ for 26 hours to obtain modified glass microspheres.

[0031] Comparative Example 3

[0032] The modification method of the glass microspheres in this comparative example adopts the following steps: glass microspheres (HS38) and hot air are mixed and introduced into the airflow drying pipeline for airflow drying. The flow rate of the hot air is set to 11 m / s and the temperature is set to 125℃. During the airflow drying, the glass microspheres are sprayed with a vinyltrimethoxysilane alcohol solution (solid content 25%) once. After the glass microspheres run in the airflow drying pipeline for 4 seconds, glass microsphere powder is obtained, and modified glass microspheres are obtained. In the whole process, the amount of vinyltrimethoxysilane used is 1.7% of the mass of HS38.

[0033] III. Experimental Examples

[0034] In this experiment, the modified glass microspheres obtained in Examples 1, 2 and Comparative Example 1 were used to prepare polyurethane adhesives for mechanical property testing. Specifically, their tensile strength and elongation at break were measured, and the results are shown in Table 1.

[0035] The method for determining tensile strength and elongation at break is as follows: Components A and B are mixed evenly at a mass ratio of 100:826 to prepare dumbbell plates with a thickness of 2 mm. The plates are cured under standard conditions for 7 days and their performance is tested using a universal tensile testing machine at a speed of 500 mm / min.

[0036] Polyurethane adhesives include:

[0037] Component A: PAPI (polymethylene polyphenyl polyisocyanate)

[0038] Component B: Composed of the following components in parts by weight: 7 parts of polyether polyol YD305, 3 parts of polyether polyol 330n9, 15 parts of glass microspheres, 2 parts of fumed silica, and 0.07 parts of dibutyltin dilaurate.

[0039] The processing of component B is as follows: polyether polyol YD305 and polyether polyol 330n are added to a dehydration reactor and dehydrated for 2 hours at 100°C and below -0.095 MPa. Then, the temperature is lowered to 35°C. The dehydrated modified glass microspheres, fumed silica and dibutyltin dilaurate are then added to the dehydration reactor and stirred under vacuum for 10 minutes to obtain component B.

[0040] The polyurethane adhesive obtained when the glass microspheres in component B are the modified glass microspheres in Example 1 is denoted as S1; the polyurethane adhesive obtained when the glass microspheres are the modified glass microspheres in Example 2 is denoted as S2; and the polyurethane adhesive obtained when the glass microspheres are the modified glass microspheres in Comparative Example 1 is denoted as D1.

[0041] In this experimental example, the modified glass microspheres obtained in Example 3, Comparative Example 2, and Comparative Example 3 were also prepared into low-density silicone rubber for mechanical property testing. Specifically, their tensile strength and elongation at break were measured, and the results are shown in Table 1.

[0042] The low-density silicone rubber comprises: 70 parts by weight of vinyl silicone rubber (60A, vinyl content 1%), 3 parts by weight of methyl silicone oil (200 cps), 18 parts by weight of calcium carbonate, and 0.5 parts by weight of silane coupling agent vinyltrimethoxysilane, mixed evenly, and then kneaded for 18 minutes at 113°C under vacuum below -0.095 MPa using a vacuum kneader. Then, 7 parts by weight of modified glass microspheres are added, and kneading is continued for 8 minutes. Finally, 1.2 parts by weight of vulcanizing agent bis(2,5-dimethyl)propoxide is added at room temperature on an open mill, and the mixture is kneaded for 8 minutes to obtain the low-density silicone rubber product. This product is then pressed into 2 mm thick sheets and vulcanized for 4.2 minutes on a flat vulcanizing machine at 180°C. After curing the vulcanized sheets under standard conditions for 7 days, they are cut into dumbbell-shaped pieces for testing their tensile strength and elongation at break. The testing speed is 500 mm / min.

[0043] When the glass microspheres are the glass microspheres in Example 3, they are denoted as S3; when the glass microspheres are the glass microspheres in Comparative Example 2, they are denoted as D2; and when the glass microspheres are the glass microspheres in Comparative Example 3, they are denoted as D3.

[0044] Table 1 Results of Mechanical Property Measurement

[0045] sample Tensile strength (MPa) Elongation at break (%) S1 5.3 382 S2 5.5 379 D1 4.7 337 S3 3.4 283 D2 3.2 261 D3 3.1 258

[0046] As shown in Table 1, the mass ratio of modifier, water, and glass microspheres used in the dry and wet modification method of Example 1 of this invention is 8:2:1000, while the mass ratio of modifier, water, and glass microspheres in the wet treatment of Comparative Example 1 is 8:5000:1000. Therefore, although the mass ratio of modifier to glass microspheres used in Example 1 and Comparative Example 1 is the same, the polyurethane adhesive prepared from the modified glass microspheres of Example 1 has higher tensile strength and elongation at break than that of the modified glass microspheres of Comparative Example 1. Thus, the modification method of this invention has higher utilization efficiency of the treatment agent. Furthermore, this invention significantly reduces the use of water.

[0047] As can be seen from the comparison between Example 3 and Comparative Example 2, when deionized water is used instead of alcohol for spraying, the strength and elongation at break of the vinyl silicone rubber are better, indicating that water has a better effect on modifying glass microspheres. This is mainly because water promotes the hydrolysis of vinyltrimethoxysilane and subsequent reactions.

[0048] As can be seen from the comparison between Example 3 and Comparative Example 3, using vinyltrimethoxysilane for multi-point spraying and finally spraying with deionized water results in better strength and elongation at break compared to using vinyltrimethoxysilane alcohol solution for a single spray. This indicates that multi-point spraying of vinyltrimethoxysilane not only makes the spraying more uniform, but more importantly, it is conducive to the orderly hydrolysis of vinyltrimethoxysilane. Moreover, the final spraying with water has a better hydrolysis effect on vinyltrimethoxysilane.

Claims

1. A method for modifying glass microspheres, characterized in that, The process includes the following steps: mixing glass microspheres with hot air and introducing them into an airflow drying pipeline for airflow drying; during the airflow drying process, spraying the glass microspheres with a silanizing modifier and water sequentially; obtaining glass microsphere powder from the outlet of the airflow drying pipeline; and then curing to obtain modified glass microspheres.

2. The method for modifying glass microspheres according to claim 1, characterized in that, The silanization modifier is sprayed more than twice.

3. The method for modifying glass microspheres according to claim 1 or 2, characterized in that, The mass ratio of the silanizing modifier, water, and glass microspheres is (8-17):(2-5):1000.

4. The method for modifying glass microspheres according to claim 3, characterized in that, The silanizing modifier was sprayed three times. The mass ratio of the first, second, and third sprays of the silanizing modifier, water, and glass microspheres was (4-6):(2-6):(1-5):(2-5):1000.

5. The method for modifying glass microspheres according to claim 1, characterized in that, Along the length of the airflow drying pipeline, at least one silanizing agent nozzle and a water nozzle are installed inside the airflow drying pipeline, and the silanizing agent and water are sprayed sequentially through the silanizing agent nozzle and the water nozzle.

6. The method for modifying glass microspheres according to claim 1 or 2, characterized in that, The silanizing modifier is one or more of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

7. The method for modifying glass microspheres according to claim 1, characterized in that, The temperature of the hot air is 110-125℃, and the wind speed is 10-13m / s.

8. The method for modifying glass microspheres according to claim 1, characterized in that, The curing temperature is 25-30℃, and the time is 26-28 hours.