Preparation method and application of organic fluorine modified nano fumed silica

Abstract

The invention belongs to the technical field of nano materials, and particularly discloses a preparation method and application of organic fluorine modified nano fumed silica, and the preparation method comprises the following steps: S1, uniformly preheating hydrophilic nano fumed silica powder as a raw material under a protective atmosphere; s2, adding an activating agent into the powder obtained in the S1 for mixing and activating, wherein the activating agent is a mixed solution of alcohol and acid or alkali; s3, adding an organic fluorine modifier into the material obtained in S2 for modification treatment, stopping heating, taking out the material after cooling, and performing vacuum drying and low-temperature removal treatment to obtain the organic fluorine modified nano fumed silica. The water contact angle of the nano fumed silica obtained through the treatment is larger than 120 degrees, the contact angle of diiodomethane is larger than 100 degrees, and the nano fumed silica shows hydrophobicity and oleophobicity and can be applied to stain-resistant, self-cleaning and super-hydrophobic materials and / or fluorosilicone rubber filler.

Description

Technical Field

[0001] The invention belongs to the technical field of nano materials and relates to a preparation method and application of organic fluorine-modified nano gas-phase silicon dioxide. Background Art

[0002] Fluorosilicone rubber can be widely used in high-end fields such as engine seals and aging-resistant sealing materials. Nano-fumed silica, as an important reinforcing filler for fluorosilicone rubber, has a great influence on the performance of fluorosilicone rubber. The water contact angle of ordinary hydrophobic nano-fumed silica is greater than 100°, and the contact angle of diiodomethane is less than 90°, showing hydrophobicity and lipophilicity. It is difficult to add, disperse and use in fluorosilicone rubber, and needs to be further modified to have hydrophobic and oleophobic characteristics, which can effectively improve the affinity of nano-fumed silica powder with rubber, and improve the transparency, strength and oil resistance of fluorosilicone rubber. Summary of the invention

[0003] The present invention provides a preparation method and application of organic fluorine-modified nano-fumed silica. The modified nano-fumed silica has a water contact angle greater than 120° and a diiodomethane contact angle greater than 100°, showing hydrophobic and oleophobic properties.

[0004] In order to achieve the above objectives, the present invention adopts the following technical solution: a method for preparing organic fluorine-modified nano-fumed silica, comprising the following steps: S1. Use hydrophilic nano-fumed silica powder as raw material and preheat evenly under protective atmosphere; S2, adding an activator to the powder of S1 for mixing and activation, wherein the activator is a mixed solution of alcohol and acid or alkali; S3, adding an organic fluorine modifier to the material obtained in S2 for modification, stopping heating, taking out the material after cooling, and vacuum drying and degassing to obtain organic fluorine modified nano fumed silica.

[0005] Furthermore, the specific surface area of ​​the hydrophilic nano-fumed silica powder is 50-400 m 2 / g.

[0006] Furthermore, S1 is preheated to a temperature of 80-100° C., and stirring and mixing are performed during preheating; the preheating time is 10-30 minutes.

[0007] Furthermore, S2 satisfies at least one of the following: The amount of the activator added is 0.5-5wt% of the powder; the activation time is 10-20min; the alcohol in the activator is methanol and / or ethanol; the acid is formic acid, acetic acid and / or hydrochloric acid; the base is one or more of ammonia water, ethylenediamine, and ethanolamine; the ratio of alcohol to acid or base is 1:1-1.5.

[0008] Further, the organic fluorine modifier in S3 is perfluoroethylethanol, perfluorohexylethanol, perfluorooctylethanol, perfluorohexyloctanol, 1H, 1H, 2H, 2H-perfluorodecyldimethylchlorosilane, 1H, 1H, 2H, 2H-perfluorodecylmethyldichlorosilane, 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, trifluoropropylmethylcyclotrisiloxane, trifluoropropylmethylcyclosilazane, heptadecafluorodecyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltriethoxysilane, tridecafluorooctyltrimethoxysilane, and one or more combinations of pentafluorooctanoic acid.

[0009] Furthermore, the amount of the organic fluorine modifier added in S3 is 5-30wt% of the powder. Furthermore, in S3, the modification temperature is 120-150°C, and the modification time is 2-3h; after the modification is completed, the temperature is lowered to below 40°C and taken out, and vacuum dried at 120°C for 1.5-2h.

[0010] Further, the activator in S2 and / or the organic fluorine modifier in S3 are added in the form of spray.

[0011] The invention also relates to organic fluorine-modified nanometer gas-phase silicon dioxide obtained by the preparation method. The present invention also relates to the application of the organic fluorine-modified nanometer gas-phase silica in anti-fouling, self-cleaning, super-hydrophobic materials and / or fluorosilicone rubber.

[0012] The present invention has the following beneficial effects: When modifying the material, the present invention first preheats the material to remove moisture in the powder, eliminates the agglomeration state of a small part of the powder, and makes the powder more fluffy; then a small amount of activating agent is added for activation treatment to make the hydroxyl groups on the surface of the fumed silica more active and conducive to the reaction; then an organic fluorine modifier is added for modification to react with the silanol groups on the surface of the fumed silica; finally, a drying and degassing treatment is performed, and the obtained organic fluorine-modified nano fumed silica powder tablet has a water contact angle greater than 120° and a diiodomethane contact angle greater than 100°, and has hydrophobic and oleophobic properties.

[0013] In the present invention, the amount of the organic fluorine modifier added is 5-30wt% of the powder. When the added amount is low, the degree of powder modification is low and the hydrophobic and oleophobic effect is poor. When the added amount is too large, the powder modification is saturated, and more free modifiers will adhere to the powder surface, and the powder will appear agglomerated, which seriously affects the powder state. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a water contact angle test diagram of the materials prepared in Example 1 to Example 4.

[0015] Figure 2 This is a diiodomethane contact angle test diagram of the materials prepared in Examples 1 to 4.

[0016] Figure 3 This is the infrared spectrum analysis diagram of the material prepared in Example 5.

[0017] Figure 4 is a scanning electron microscope image of the material prepared in Example 5.

[0018] Figure 5 It is a state diagram of the materials prepared in Example 1, Comparative Example 1 and Comparative Example 3. DETAILED DESCRIPTION

[0019] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0020] Example 1 Weigh 100g of the specific surface area of ​​150m 2 / g hydrophilic nano-fumed silica powder was put into the powder modifier, sealed, filled with nitrogen to expel air. Stirring was started, heating was started at 80℃, and pre-dispersed for 30min. 2.5g of methanol: acetic acid 1:1 (v:v) mixed liquid was added to the atomizer under nitrogen pressure, and the activation reaction was carried out for 20min. 30g of trifluoropropyltrichlorosilane was added to the atomizer under nitrogen pressure, the temperature was raised to 120℃, and the reaction was carried out for 3h.

[0021] Example 2 Weigh 100g of the specific surface area of ​​90m 2 / g hydrophilic nano-fumed silica powder is put into the powder modifier, sealed, filled with nitrogen to expel air. Stirring is turned on, heating is turned on to 80℃, and pre-dispersed for 30 minutes. 2g of ethanol: acetic acid 1:1 (v:v) mixed liquid is added to the atomizer under nitrogen pressure, and the activation reaction is carried out for 20 minutes. 25g of trifluoropropylmethylcyclotrisiloxane is added to the atomizer under nitrogen pressure, the temperature is raised to 120℃, and the reaction is carried out for 2 hours.

[0022] Example 3 Weigh 100g of the specific surface area of ​​380m 2 / g hydrophilic nano-fumed silica powder was put into the powder modifier, sealed, filled with nitrogen and expelled air. Stirring was started, heating was started at 100℃, and pre-dispersed for 20min. 3g of methanol: hydrochloric acid 1:1 (v:v) mixed liquid was added to the atomizer under nitrogen pressure, and the activation reaction was carried out for 10min. 20g of 1H, 1H, 2H, 2H-perfluorodecylmethyldichlorosilane was added to the atomizer under nitrogen pressure, the temperature was raised to 150℃, and the reaction was carried out for 2.5h.

[0023] Example 4 Weigh 100g of the specific surface area of ​​200m 2 / g hydrophilic nano-fumed silica powder was put into the powder modifier, sealed, filled with nitrogen and expelled air. Stirring was started, heating was started at 100℃, and pre-dispersed for 20 minutes. 0.5g of methanol: hydrochloric acid 1:1 (v:v) mixed liquid was added to the atomizer under nitrogen pressure, and the activation reaction was carried out for 20 minutes. 25g of 1H, 1H, 2H, 2H-perfluorodecylmethyldichlorosilane was added to the atomizer under nitrogen pressure, the temperature was raised to 150℃, and the reaction was carried out for 2.5 hours.

[0024] Example 5 Weigh 100g of the specific surface area of ​​380m 2 / g hydrophilic nano-fumed silica powder was put into the powder modifier, sealed, filled with nitrogen to expel air. Stirring was started, heating was started at 100℃, and pre-dispersed for 20min. 3g of methanol: ammonia water 1:1 (v:v) mixed liquid was added to the atomizer under nitrogen pressure, and the activation reaction was carried out for 10min. 20g of trifluoropropylmethylcyclotrisilazane was added to the atomizer under nitrogen pressure, the temperature was raised to 140℃, and the reaction was carried out for 2.5h.

[0025] Example 6 Weigh 100g of the specific surface area of ​​380m 2 / g hydrophilic nano-fumed silica powder is put into the powder modifier, sealed, filled with nitrogen to expel air. Stirring is turned on, heating is turned on to 100℃, and pre-dispersed for 10min. 5g of ethanol:ethanolamine 1:1.5 (v:v) mixed liquid is added to the atomizer under nitrogen pressure, and the activation reaction is carried out for 20min. 15g of trifluoropropylmethylcyclotrisilazane is added to the atomizer under nitrogen pressure, the temperature is raised to 120℃, and the reaction is carried out for 2h.

[0026] Example 7 Weigh 100g of the specific surface area of ​​50m 2 / g hydrophilic nano-fumed silica powder is put into the powder modifier, sealed, filled with nitrogen to expel air. Turn on the stirring, heat to 100℃, and pre-disperse for 10 minutes. Add 1.5g of methanol:ethylenediamine 1:1.3 (v:v) mixed liquid to the atomizer under nitrogen pressure, and activate the reaction for 20 minutes. Add 6g of 17fluorodecyltriethoxysilane and 21g of 13fluorooctyltriethoxysilane to the atomizer under nitrogen pressure, raise the temperature to 130℃, and react for 3 hours.

[0027] Example 8 Weigh 100g of the specific surface area of ​​200m 2 / g hydrophilic nano-fumed silica powder is put into the powder modifier, sealed, filled with nitrogen to expel air. Turn on the stirring, heat to 100℃, and pre-disperse for 10 minutes. Add 4g of ethanol:acetic acid 1:1.2 (v:v) mixed liquid to the atomizer under nitrogen pressure, and activate the reaction for 20 minutes. Add 3g of perfluoroethylethanol and 17g of heptadecafluorodecyltrimethoxysilane to the atomizer under nitrogen pressure, raise the temperature to 120℃, and react for 2 hours.

[0028] Example 9 Weigh 100g of the specific surface area of ​​300m 2 / g hydrophilic nano-fumed silica powder was put into the powder modifier, sealed, filled with nitrogen and expelled air. Stirring was started, heating was started at 100℃, and pre-dispersed for 20min. 0.5g of ethanol: hydrochloric acid 1:1.5 (v:v) mixed liquid was added to the atomizer under nitrogen pressure, and the activation reaction was carried out for 15min. 24g of 1H, 1H, 2H, 2H-perfluorodecyldimethylchlorosilane was added to the atomizer under nitrogen pressure, the temperature was raised to 150℃, and the reaction was carried out for 2h.

[0029] Example 10 Weigh 100g of the specific surface area of ​​300m 2 / g hydrophilic nano-fumed silica powder was put into the powder modifier, sealed, filled with nitrogen and expelled air. Stirring was started, heating was started at 80℃, and pre-dispersed for 30min. 0.5g of methanol: hydrochloric acid 1:1.2 (v:v) mixed liquid was added to the atomizer under nitrogen pressure, and the activation reaction was carried out for 15min. 26g of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane was added to the atomizer under nitrogen pressure, the temperature was raised to 150℃, and the reaction was carried out for 3h.

[0030] Comparative Example 1 Weigh 5g of the specific surface area of ​​380m 2 / g of hydrophilic nano-fumed silica powder was added with 80g of ethanol:acetic acid 1:1 (v:v) mixed liquid, stirred evenly, and then 1.3g of 1H, 1H, 2H, 2H-perfluorodecylmethyldichlorosilane modifier was added. The mixture was kept at 60℃ for 8h. After the reaction was completed, the sample was taken out and dried in an oven at 120℃ to obtain a solid.

[0031] Comparative Example 2 Weigh 100g of the specific surface area of ​​90m 2 / g hydrophilic nano-fumed silica powder is put into the powder modifier, sealed, filled with nitrogen to expel air. Stirring is turned on, heating is turned on to 80℃, and pre-dispersed for 30min. 2g of ethanol:acetic acid 1:1 (v:v) mixed liquid is added to the atomizer under nitrogen pressure, and the activation reaction is carried out for 20min. 1.0g of trifluoropropylmethylcyclotrisiloxane is added to the atomizer under nitrogen pressure, the temperature is raised to 120℃, and the reaction is carried out for 2h.

[0032] Comparative Example 3 Weigh 100g of the specific surface area of ​​90m 2 / g hydrophilic nano-fumed silica powder is put into the powder modifier, sealed, filled with nitrogen to expel air. Stirring is turned on, heating is turned on to 80℃, and pre-dispersed for 30min. 2g of ethanol:acetic acid 1:1 (v:v) mixed liquid is added to the atomizer under nitrogen pressure, and the activation reaction is carried out for 20min. 50g of trifluoropropylmethylcyclotrisiloxane is added to the atomizer under nitrogen pressure, the temperature is raised to 120℃, and the reaction is carried out for 2h.

[0033] The powders prepared in the above examples and comparative examples were tableted, and the water contact angle and diiodomethane contact angle were tested to observe the state of the powders, as shown in Table 1.

[0034] Table 1

[0035] As can be seen from Table 1, the hydrophilic powder has been prepared into a hydrophobic and oleophobic powder filler in the embodiment, and the hydrophobic properties of the powder are different when the activator, modifier and addition amount are different. As can be seen from the comparative example, when less modifier is added, the hydrophobic and oleophobic properties of the powder are weak, and when more modifier is added, the powder clumps seriously and cannot be prepared into a fluffy powder.

[0036] Figure 3 This is the infrared spectrum of the material obtained in Example 5, Figure 4 The SEM image of the material is shown in Figure 1. The infrared spectrum shows that the -1 and 1268 cm -1The strong absorption peak of CF appears, indicating that the organic fluorine group is stably present in the powder material, and the material exhibits hydrophobic and oleophobic properties. Figure 5 The material particles prepared in Example 1 are uniform without any agglomeration or aggregation, while those in Comparative Example 1 are in block form, and the powders in Comparative Example 3 are aggregated to a greater extent.

[0037] The above embodiments describe the preferred implementation of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing organic fluorine-modified nano-fumed silica, characterized in that: The following steps are involved: S1. Use hydrophilic nano-fumed silica powder as raw material and preheat evenly under protective atmosphere; S2, adding an activator to the powder of S1 for mixing and activation, wherein the activator is a mixed solution of alcohol and acid or alkali; S3, adding an organic fluorine modifier to the material obtained in S2 for modification, stopping heating, taking out the material after cooling, and vacuum drying and degassing to obtain organic fluorine modified nano fumed silica.

2. The preparation method according to claim 1, characterized in that: The specific surface area of ​​the hydrophilic nano-fumed silica powder is 50-400 m 2 / g.

3. The preparation method according to claim 1, characterized in that: S1 is preheated to a temperature of 80-100°C, and stirring and mixing are performed during preheating; the preheating time is 10-30 minutes.

4. The preparation method according to claim 1, characterized in that: S2 satisfies at least one of the following: The amount of the activator added is 0.5-5wt% of the powder; the activation time is 10-20min; the alcohol in the activator is methanol and / or ethanol; the acid is formic acid, acetic acid and / or hydrochloric acid; the base is one or more of ammonia water, ethylenediamine, and ethanolamine; the ratio of alcohol to acid or base is 1:1-1.

5.

5. The preparation method according to claim 1, characterized in that: The organic fluorine modifier in S3 is one or more combinations of perfluoroethylethanol, perfluorohexylethanol, perfluorooctylethanol, perfluorohexyloctanol, 1H, 1H, 2H, 2H-perfluorodecyldimethylchlorosilane, 1H, 1H, 2H, 2H-perfluorodecylmethyldichlorosilane, 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, trifluoropropylmethylcyclotrisiloxane, trifluoropropylmethylcyclosilazane, heptadecafluorodecyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltriethoxysilane, tridecafluorooctyltrimethoxysilane, and pentafluorooctanoic acid.

6. The preparation method according to claim 1, characterized in that: The amount of organic fluorine modifier added in S3 is 5~30wt% of the powder.

7. The preparation method according to claim 1, characterized in that: The modification temperature in S3 is 120-150°C, and the modification time is 2-3h. After the modification is completed, the temperature is lowered to below 40°C and taken out, and vacuum dried at 120°C for 1.5-2h.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The activator in S2 and / or the organic fluorine modifier in S3 are added in the form of spray.

9. The organic fluorine-modified nano-fumed silica obtained according to the preparation method according to any one of claims 1 to 8.

10. Use of the organic fluorine-modified nano-fumed silica according to claim 9 in anti-fouling, self-cleaning, super-hydrophobic materials and / or fluorosilicone rubber.

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