Preparation method of environment-friendly fluorine-free super-hydrophobic powder and product

Abstract

The application discloses a kind of preparation methods and products of environment-friendly fluorine-free super-hydrophobic powder, it is related to super-hydrophobic material technical field, to solve the problem of not being environment-friendly or more complex of existing super-hydrophobic silicon dioxide preparation method;The application includes adding organic acid to small molecule monohydric alcohol to adjust pH, mix uniformly with water;Add organosilicon silane coupling agent, and fully hydrolyze to obtain solution A by stirring reaction;SiO2 is fully stirred and dispersed uniformly to obtain solution B;In the case where solution B is stirred, add clear and sufficient solution A, and set temperature to 40-50 DEG C, fully stir and react, then stand at room temperature and react fully, dry to remove liquid phase to obtain super-hydrophobic powder;The preparation method of the application is simple, green and environmentally friendly, low in cost, and the prepared super-hydrophobic powder is free of fluorine and has excellent hydrophobic performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of super-hydrophobic materials, in particular to a preparation method of an environmentally-friendly fluorine-free super-hydrophobic powder and a product. BACKGROUND

[0002] Scientists have found that water droplets on the surface of a lotus leaf present a spherical shape that cannot be wetted and can roll off with dust. The reason is that the surface of the lotus leaf is composed of micrometer-level papillae and nanometer-level wax crystals distributed on the papillae, and the micro-nano rough surface has a relatively low surface energy. There are many plant surfaces with super-hydrophobicity in nature, such as taro leaves, cabbages, rice leaves and the like. A super-hydrophobic surface generally refers to a material surface with a static water contact angle of a water droplet of a certain size on the material surface greater than 150° and a rolling angle less than 10°, such as the lotus leaf, the taro leaf and the like mentioned above, which are typical super-hydrophobic surfaces in nature. The super-hydrophobic surface has a good application prospect in the fields of aviation, automobiles, corrosion resistance, buildings and water resistance due to its self-cleaning, corrosion resistance, ice prevention and drag reduction characteristics.

[0003] Internationally, the research on the super-hydrophobic surface started in the 1950s. By the end of the 1990s, with the development of surface science and technology, especially the improvement of surface research technical means, the preparation of a super-hydrophobic surface by simulating the surface structure and performance of a natural super-hydrophobic material has attracted people's attention.

[0004] Generally, two aspects need to be completed to construct a super-hydrophobic surface, one is to prepare a rough surface with a micro-nano structure, and the other is to reduce the surface energy of the material surface by using a low-surface-energy substance. At present, many methods have been developed to prepare a super-hydrophobic surface, such as etching, template method, vapor deposition, sol-gel, electrospinning and hydrothermal synthesis method and the like. These methods have problems of harsh experimental conditions, complicated steps or high cost and the like.

[0005] In the invention patent application with the publication number CN107128932A and the name of a preparation method of a hydrophobic silicon dioxide for VOC adsorption, the preparation method comprises the following steps: (1) preparing a mixed solution by mixing nitric acid, deionized water and anhydrous ethanol in a container; (2) preparing a mixed solution by mixing a silicon dioxide source, anhydrous ethanol and deionized water, and then adding a composite coupling agent and stirring uniformly; (3) quickly pouring the solution obtained in the step (2) into the mixed solution obtained in the step (1), controlling the solution PH to be between 2 and 6 and stirring for several hours; (4) sealing the container and placing it to age for 2 hours; (5) extracting, washing and standing at room temperature after the gel after surface modification and solvent replacement; and (6) drying the washed gel, and then performing airflow superfine crushing to obtain a finished product. Although hydrophobicity is obtained, super-hydrophobicity is not obtained, and in addition, the preparation process involves extraction, washing and the like, and the preparation process is relatively complex. SUMMARY

[0006] The present application aims to provide a preparation method of environment-friendly fluorine-free super-hydrophobic powder and a product, so as to solve the problems of the existing super-hydrophobic silica preparation method being not environment-friendly or being relatively complex.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solution: a preparation method of environment-friendly fluorine-free super-hydrophobic powder, comprising the following specific steps:

[0008] S1. Hydrolysis of organic silane coupling agent: add organic acid to 9-12 parts by mass of small-molecule monohydric alcohol to adjust the pH value to 4-5, and then add 3-5 parts by mass of deionized water and mix uniformly; add 6-12 parts by mass of organic silane coupling agent to the mixed solution, and add in multiple portions with a certain interval, and stir and react at room temperature while adding to make it fully hydrolyzed to obtain solution A; during the stirring and reaction process and after the preparation is completed, ensure that solution A is clear, and if it is turbid, re-prepare solution A;

[0009] S2. Preparation of SiO2 suspension liquid: weigh a certain amount of dried SiO2, put it into a container, add deionized water, and fully stir and disperse at room temperature to obtain solution B; wherein the mass ratio of SiO2 to deionized water is 0.25-1, and the mass ratio is positively correlated with the particle size of SiO2, that is, the smaller the particle size of SiO2, the smaller the mass ratio of SiO2 to deionized water;

[0010] S3. Preparation of super-hydrophobic powder: add sufficient solution A to solution B under stirring, and set the temperature to 40-50 DEG C for fully stirring and reacting, and then stand at room temperature for fully reacting, and then dry to remove the liquid phase to obtain super-hydrophobic powder.

[0011] Preferably, in the above step S1, each portion of the organic silane coupling agent is 1.5-2 ml, and each portion is added at an interval of 2-3 min.

[0012] Preferably, in the above step S1, the organic acid is analytical pure acetic acid, and if it needs to be replaced, analytical pure formic acid, propionic acid or butyric acid is used.

[0013] Preferably, in the above step S1, the small-molecule monohydric alcohol is analytical pure methanol, and if it needs to be replaced, analytical pure ethanol, propanol or butanol is used.

[0014] Preferably, in the above step S1, the organic silane coupling agent is methyltrimethoxysilane or n-octyltriethoxysilane.

[0015] Preferably, in the above step S1, after the small-molecule monohydric alcohol is added to deionized water, it is sealed and stirred and dispersed uniformly by a magnetic stirrer for 5-10 min.

[0016] Preferably, in step S2 above: after adding SiO2 to deionized water, it is stirred and dispersed evenly with a magnetic stirrer for 20-30 minutes; the particle size of SiO2 is 10nm-10000nm.

[0017] Preferably, in step S3 above, the mass ratio of SiO2 to silane coupling agent in solution A and solution B is 4.17-8.33.

[0018] Preferably, in step S3 above, after adding solution A to solution B, the mixture is stirred for 20-30 minutes, and after stirring, it is allowed to stand at room temperature for 4-6 hours. The mixture is then dried in an oven at 95-105℃.

[0019] Another technical solution provided by the present invention: an environmentally friendly fluorine-free superhydrophobic powder prepared according to the above preparation method, with a contact angle greater than or equal to 151°, a dense irregular protrusion SEM microstructure of the powder, and the powder being particles with a micron / nano-level roughness with a maximum size of less than 10 μm.

[0020] Preferably, the superhydrophobic powder is mixed with an adhesive to increase the adhesion between the superhydrophobic surface and the substrate, serving as a surface superhydrophobic coating.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] The preparation method and product of this environmentally friendly fluorine-free superhydrophobic powder do not require expensive and somewhat toxic fluorinated polymers / compounds as low surface energy materials. They only require relatively safe and environmentally friendly organosilicon materials. They do not require costly materials such as ceramic particles and carbon nanotubes as raw materials. They only require low-cost and readily available synthetic SiO2. The preparation process is simple, the required experimental equipment is simple and readily available, and the process is easy to control. The obtained product has excellent superhydrophobic properties and can be used in combination with adhesives as a superhydrophobic coating. The preparation method of this environmentally friendly fluorine-free superhydrophobic powder is easy to apply in large-scale production. Attached Figure Description

[0023] Figure 1 This is a SEM image of the environmentally friendly, fluorine-free, superhydrophobic powder prepared in Example 1.

[0024] Figure 2 The image shows the XRD pattern of the environmentally friendly, fluorine-free, superhydrophobic powder prepared in Example 1.

[0025] Figure 3 The image shows the FTIR spectrum of the environmentally friendly, fluorine-free, superhydrophobic powder prepared in Example 1.

[0026] Figure 4 The static wettability image of the environmentally friendly fluorine-free superhydrophobic powder prepared in Example 1.

[0027] Figure 5 The hydrophilicity schematic diagram of the environmentally friendly fluorine-free super-hydrophobic powder prepared in Example 1, the left side of the figure is the SiO2 powder of raw material, and the right side is the super-hydrophobic powder.

[0028] Figure 6 The hydrophobicity schematic diagram of the environmentally friendly fluorine-free super-hydrophobic powder prepared in Example 2 coated on the surface of steel sheet and concrete.

[0029] Figure 7 The principle schematic of the preparation of the hydrolysis liquid of Example 3 and the condensation reaction with silicon dioxide. DETAILED DESCRIPTION

[0030] A preparation method of an environmentally friendly fluorine-free super-hydrophobic powder, comprising the following specific steps:

[0031] S1. Hydrolysis of organosilane coupling agent: add organic acid to 9-12 parts by mass of small molecule monohydric alcohol to adjust the pH value to 4-5, add 3-5 parts by mass of deionized water, and mix uniformly, wherein the organic acid is preferably analytical pure acetic acid, and if necessary, analytical pure formic acid, propionic acid or butyric acid can also be used; the small molecule monohydric alcohol is analytical pure methanol, and if necessary, analytical pure ethanol, propanol or butanol can also be used; optionally, after the small molecule monohydric alcohol is added to deionized water, it is sealed and stirred and dispersed uniformly for 5-10 min by a magnetic stirrer; 6-12 parts by mass of organosilane coupling agent is added to the mixed solution, for reference, methyltrimethoxysilane or n-octyltriethoxysilane can be used, and the addition is divided into multiple portions, each portion is added at a certain interval, and the solution A is obtained by fully hydrolyzing under stirring at room temperature, for example, after the addition is completed, the stirring reaction is continued at room temperature for 20-30 min; during the stirring reaction process and after the preparation is completed, the solution A is ensured to be clear, if it is turbid, the solution A is reconfigured; specifically, if the hydrolysis liquid is clear during the dropping process, it is considered to be completely hydrolyzed, if the hydrolysis liquid is turbid, the coupling agent is excessive and cannot be completely hydrolyzed, and the prepared organosilane coupling agent hydrolysis liquid should be used as soon as possible to avoid that the hydrolysis liquid is turbid and invalid due to long storage time; in a more preferred embodiment, the organosilane coupling agent is selected to be 1.5-2 ml per portion, and it is preferable to add one portion every 2-3 min;

[0032] S2. Preparation of SiO2 suspension liquid: a certain amount of dried SiO2 is weighed and put into a container, deionized water is added, and stirred and dispersed uniformly at room temperature to obtain solution B, and optionally, the SiO2 added to the deionized water is stirred and dispersed uniformly for 20-30 min by a magnetic stirrer; wherein the mass ratio of SiO2 to deionized water is 0.25-1, and the mass ratio is positively correlated with the particle size of SiO2, that is, the smaller the particle size of SiO2, the smaller the mass ratio of SiO2 to deionized water;

[0033] S3. Preparation of super-hydrophobic powder: add sufficient amount of solution A under stirring of solution B, and set the temperature to 40-50℃, fully stir the reaction (for example, fully stir the reaction for 20-30 min), then stand at room temperature for reaction for a sufficient time (generally 4-6 h), dry to remove the liquid phase to obtain the super-hydrophobic powder, and the drying can be performed by oven drying at 95-105℃; it is advisable that the mass ratio of SiO2 to silane coupling agent in solution A and solution B is controlled to be 4.17-8.33, and the silane coupling agent can be in excess but cannot be less, otherwise the hydrophobicity of the product will be affected.

[0034] In the above step S2, the particle size of SiO2 can be 10 nm-10000 nm, according to the particle size, it is advisable that the mass ratio of SiO2 to deionized water is 0.25-0.3 for 200 nm or less, 0.3-0.4 for 200-500 nm, 0.4-0.5 for 500-1000 nm, 0.5-0.6 for 1000-2000 nm, 0.6-0.7 for 2000-3000 nm, 0.7-0.8 for 3000-4500 nm, 0.8-0.9 for 4500-6000 nm, 0.9-0.95 for 6000-8000 nm, and 0.95-1 for 8000-10000 nm, of course, the above ratios can be adjusted within a certain range, and the mass ratio is positively correlated with the particle size of SiO2, the main reason is that the smaller the particle size of SiO2, the larger the specific surface area, and the better the adsorption capacity;

[0035] The super-hydrophobic powder prepared by the above preparation method has a contact angle of not less than 151°, and the SEM microstructure of the powder is a dense irregular protrusion, and the powder is a micron / nanometer level roughness particle with a maximum size of less than 10 μm. Figure 1 , the powder has a maximum size of less than 10 μm.

[0036] In addition, the room temperature in the above preparation process is generally 20±5℃.

[0037] Example 1

[0038] Add acetic acid to 12 parts of methanol solution to adjust the pH value to 4-5, mix with 4 parts of deionized water, seal and stir for 5 min, then add 10 parts of n-octyl triethoxysilane to the mixed solution, add 1.5 ml each time with an interval of 2 min, continue to add, and stir while adding to fully hydrolyze.

[0039] Weigh 50g of dried SiO2 with a particle size of 30nm and place it in a three-necked flask. Add 200g of deionized water and stir thoroughly. While stirring, add the hydrolysate of clear silane coupling agent. The mass ratio of SiO2 to silane coupling agent is controlled at 5:1. Then place it on a magnetic stirrer and stir at 40-50℃ for 20min. Let it stand for 6h and dry it in an oven at 105℃ to obtain superhydrophobic powder.

[0040] Figure 1 The image shows an SEM image of the environmentally friendly, fluorine-free, superhydrophobic powder prepared in Example 1. As can be seen from the image, the SEM microstructure of the powder consists of dense, irregular protrusions, and the powder consists of particles with a micron / nano-scale roughness with a maximum size of less than 10 μm.

[0041] Figure 2 The image shows the XRD pattern of the environmentally friendly fluorine-free superhydrophobic powder prepared in Example 1. The superhydrophobic powder has a crystal structure that is basically the same as that of SiO2.

[0042] Figure 3 The image shows the FTIR spectrum of the environmentally friendly fluorine-free superhydrophobic powder prepared in Example 1. The chemical groups of this superhydrophobic powder are basically the same as those of SiO2.

[0043] Figure 4 The static wettability image of the environmentally friendly fluorine-free superhydrophobic powder prepared in Example 1 shows that the water droplets on the surface of the superhydrophobic powder are spherical with a contact angle of 151.68°, indicating good superhydrophobicity.

[0044] Figure 5 SiO2 powder as raw material ( Figure 5 The bottle on the left and the environmentally friendly fluorine-free superhydrophobic powder prepared in Example 1 (in the left bottle) Figure 5 A schematic diagram of the hydrophilicity of the sample in the bottle on the right. It can be observed that the superhydrophobic powder is immiscible with water, while the SiO2 powder of the raw material has good dispersibility in water.

[0045] Example 2

[0046] Add acetic acid dropwise to 12 parts isopropanol solution to adjust the pH to 4-5, mix with 4 parts deionized water, seal and stir for 5 minutes. Then add 12 parts methyltrimethoxysilane to the mixture, adding 2 ml at a time with a 3-minute interval, stirring constantly to ensure complete hydrolysis.

[0047] Take 50g of dried SiO2 with particle size of 10μm, put into a three-necked flask, add 50g of deionized water, fully stir and mix, under stirring, add clear hydrolysis solution of silane coupling agent, control the mass ratio of SiO2 and silane coupling agent to be 6:1, then place on a magnetic stirrer under 40-50℃ for 20min, stand for 4h of reaction, dry in an oven at 105℃, obtain super-hydrophobic powder, measure the contact angle to be greater than 151°.

[0048] Figure 6 The schematic diagram of hydrophobicity of the environment-friendly fluorine-free super-hydrophobic powder prepared in Example 2 coated on the surface of steel sheet and concrete. It can be observed that the liquid drops on the surface of the coating are spherical, and have good super-hydrophobicity.

[0049] Example 3

[0050] Drop acetic acid into 9 parts of isopropyl alcohol solution to adjust the pH value to 4-5, mix with 3 parts of deionized water, seal and stir for 5min, then add 6 parts of methyltrimethoxysilane to the mixture, add 1.5ml each time with interval of 3min, continue to add, and stir to fully hydrolyze.

[0051] Take 50g of dried SiO2 with particle size of 20nm, put into a three-necked flask, add 200g of deionized water, fully stir and mix, under stirring, add clear hydrolysis solution of silane coupling agent, control the mass ratio of SiO2 and silane coupling agent to be 8:1, then place on a magnetic stirrer under 40-50℃ for 20min, stand for 4h of reaction, dry in an oven at 105℃, obtain super-hydrophobic powder, measure the contact angle to be greater than 151°.

[0052] Mix the prepared super-hydrophobic powder with epoxy resin glue, phenolic resin glue, polyurethane glue and other adhesives, spray on the surface of glass or metal and other materials to be used as surface super-hydrophobic coating.

[0053] The above is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be limited by the protection scope defined by the claims.

[0054] The part not described in the present application is the known technology of the person skilled in the art.

Claims

1. A method for preparing an environmentally friendly fluorine-free superhydrophobic powder, characterized in that, The method comprises the following specific steps: S1. Hydrolysis of organosilane coupling agent: add organic acid to 9-12 parts by mass of small molecule monohydric alcohol to adjust the pH value to 4-5, add 3-5 parts by mass of deionized water and mix uniformly; add 6-12 parts by mass of organosilane coupling agent to the mixed solution, the organosilane coupling agent is methyltrimethoxysilane or n-octyltriethoxysilane, the addition is divided into multiple portions, each portion is 1.5-2 mL, and each portion is added at an interval of 2-3 min, and the solution A is obtained by fully hydrolyzing under stirring at room temperature; during the stirring reaction and after the preparation is completed, the solution A is ensured to be clear, and if it is turbid, the solution A is reconfigured; S2. Preparation of SiO2 suspension liquid: a certain amount of dried SiO2 is weighed and placed in a container, deionized water is added, and the mixture is fully stirred and dispersed uniformly at room temperature to obtain solution B; wherein the mass ratio of SiO2 to deionized water is 0.25-1, and the mass ratio is positively correlated with the particle size of SiO2, that is, the smaller the particle size of SiO2, the smaller the mass ratio of SiO2 to deionized water; S3. Preparation of super-hydrophobic powder: under the stirring of solution B, a sufficient amount of solution A is added, the mass ratio of SiO2 to silane coupling agent is 4.17-8.33, the temperature is set to 40-50 DEG C, the reaction is fully stirred, and then it is left to stand at room temperature for sufficient reaction, and the liquid phase is removed by drying to obtain super-hydrophobic powder, the contact angle of the super-hydrophobic powder is greater than or equal to 151 DEG.

2. The preparation method of the environmentally friendly fluorine-free super-hydrophobic powder according to claim 1, characterized in that: In the step S1, the organic acid is analytical pure acetic acid, and if it needs to be replaced, analytical pure formic acid, propionic acid or butyric acid is used.

3. The preparation method of the environmentally friendly fluorine-free super-hydrophobic powder according to claim 1, characterized in that: In the step S1, the small molecule monohydric alcohol is analytical pure methanol, and if it needs to be replaced, analytical pure ethanol, propanol or butanol is used.

4. The preparation method of the environmentally friendly fluorine-free super-hydrophobic powder according to claim 1, characterized in that: In the step S1, the small molecule monohydric alcohol is added to deionized water and then sealed and stirred by a magnetic stirrer for 5-10 min.

5. The method according to claim 1, wherein the method is characterized by, In the step S2, the SiO2 is added to deionized water and then stirred by a magnetic stirrer for 20-30 min; the particle size of SiO2 is 10 nm-10,000 nm.

6. The preparation method of the environmentally friendly fluorine-free super-hydrophobic powder according to claim 1, characterized in that: In the step S3, after solution A is added to solution B, the reaction is fully stirred for 20-30 min, and then it is left to stand at room temperature for 4-6 h, and the drying is performed by an oven at 95-105 DEG C.

7. An environmentally friendly fluorine-free superhydrophobic powder prepared according to the preparation method of any one of claims 1 to 6, characterized in that: The SEM microstructure of the super-hydrophobic powder is a dense irregular protrusion, and the powder is a particle with micron / nanometer level roughness with a maximum size of less than 10 μm.

8. The environmentally friendly fluorine-free super-hydrophobic powder according to claim 7, characterized in that: The super-hydrophobic powder is mixed with an adhesive to increase the bonding force of the super-hydrophobic surface and the substrate, and is used as a surface super-hydrophobic coating.

Images