KR20180086838A - Superhydrophobic film and manufacturing method thereof - Google Patents

Abstract

The present application relates to a superhydrophobic film and to a manufacturing method thereof. The present application can provide the superhydrophobic film, which is stable at high temperature, an acid, a base and an organic solvent by using a fluororesin foam having an open cell structure of micron or less, and the manufacturing method thereof. The superhydrophobic film and the manufacturing method thereof of the present application are useful for various fields such as self-cleaning, antifouling, anti-icing, oil-water separation, corrosion resistance and the like.

Description

Technical Field [0001] The present invention relates to a superhydrophobic film and a manufacturing method thereof,

The present application relates to a superhydrophobic film and a manufacturing method thereof.

Superhydropobicity has various applications such as self-cleaning, antifouling, anti-icing, oil-water separation, and corrosion resistance.

The supercritical water is usually made by forming submicron projections using a hydrophobic material. However, the conventional super-hydrophobic coating process is complicated and expensive, so it is difficult to apply to a large area and the surface damage is not restored. In addition, super-hydrophobic coating processes are not stable at high temperatures or in acids, bases and organic solvents.

Conventional fluororesin foams can be formed in a closed cell structure having a size of 1 to 200 mu m using a forming agent (Patent Document 1). Such a fluororesin foam has a limitation that it does not show superhydrophobicity.

U.S. Patent Publication No. 5340843

The present application provides a superhydrophobic film which is stable at high temperatures or in an acid, a base and an organic solvent, and a process for producing the same.

The present application relates to superhydrophobic films. In this specification, hydrophilicity refers to a case where the contact angle of a water droplet is 90 degrees or more, while reference to wettability with respect to water. A case where the contact angle of the water droplet is 110 degrees to 140 degrees can be defined as high water, It can be defined as superhydrophobic. The superhydrophobic film of the present application may comprise fluororesin foam. In the present specification, the fluororesin foam may mean a substance in which the gas exists in a dispersed phase in the fluororesin dispersion medium. The portion in which the gas exists in the fluororesin foam can be referred to as pores.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an exemplary structure of a superhydrophobic film comprising a fluororesin foam of the present application. Fig. 1, the fluororesin foam contains a fluororesin 1 and pores 2. The fluororesin foam may be formed in an open cell structure. The ultrafine hydrophobic film of the present application can exhibit supersensitivity by controlling the surface roughness by including an open cell structure of a fluororesin foam.

In this specification, a foam of an open cell structure may mean a foam of a structure in which pores are connected to each other. The pores included in the foam of the open cell structure can be referred to as open pores. The term corresponding to the open cell may be a closed cell. Each of the pores contained in the foam of the closed cell structure is isolated and the pores included in the foam of the closed cell structure may be referred to as closed pores.

The pores of the fluororesin foam may have a size of 50 nm to 5 탆, specifically 100 nm to 600 nm. The size of the pores may mean an average size of a plurality of pores when the fluororesin foam includes a plurality of pores. The size of the pores can be measured by a shape analysis method using a Scanning Electron Microscope (SEM) equipment. If the pore size of the fluororesin foam is within the above range, it may be more advantageous to exhibit superhydrophobicity.

The volume ratio of the pores of the fluororesin foam may be 10% to 90%, specifically 50% to 80%. The volume ratio of the pores may mean a ratio to a case where the total volume of the fluororesin foam is 100%. The volume ratio of the pores may be deduced from the volume ratio of the template particles used in the production of the fluororesin foam, and may be proportional to, for example, the volume ratio of the template particles. When the volume ratio of the pores of the fluororesin foam is within the above range, it may be more advantageous to exhibit superhydrophobicity.

As the fluororesin of the fluororesin foam, polytetrafluoroethylene, perfluoroalkoxy-polytetrafluoroethylene copolymer, fluorinated ethylene propylene or ethylene-tetrafluoroethylene can be used. These fluorine resins are advantageous in that they are stable at high temperatures, acids, bases, organic solvents and the like.

The fluororesin of the fluororesin foam may refer to a material in which the fluororesin particles are sintered. The pores of the fluororesin foam may be filled with air.

The thickness of the fluororesin foam may be suitably selected in consideration of the object of the present application. For example, the fluororesin foam may have a thickness of 10 to 1000 탆. The thickness of the fluororesin foam may be more advantageous for exhibiting supersensitivity.

The contact angle of the super-hydrophobic film with respect to water may be more than 140 degrees. The contact angle with respect to the water can be measured by Drop Shape Analysis using a DSA100 instrument from Kruss. The superhydrophobic film of the present application can achieve a high contact angle with water by forming a fluororesin foam with an open cell structure of submicron size.

The supercritical water film may further include a substrate on one side of the fluororesin foam. As the above substrate, a known substrate used in the production of a film may be used. As the substrate, an inorganic film such as glass or silicon, a plastic film, or the like can be used. Alternatively, the substrate may be an object for which the surface is to be modified to superhydrophobicity.

The present application relates to a method for producing a superhydrophobic film. The supercritical water-soluble film can be produced through the above-described production method. Fig. 2 is a schematic diagram for explaining a method of manufacturing the superhydrophobic film of the present application. Fig. The manufacturing method of the present application includes a first step of applying a mixture containing template particles (3) having a size of 0.03 mu m to 10 mu m, fluororesin particles (4) and a residual solvent (5) onto a substrate (6); A second step of evaporating the remaining solvent in the coated mixture to dry it; A third step of heating the dried mixture to sinter the fluororesin particles; And a fourth step of washing the template particles in the sintered mixture to form a fluororesin foam.

The weight ratio of the fluororesin particles to the template particles in the mixture of the first step may be appropriately adjusted in consideration of the volume ratio of the fluororesin foam to be produced. In one example, the mixture of the first step may contain the template particles and the fluororesin particles in a weight ratio of 10: 1 to 1:10. Specifically, the weight ratio of the template particles to the fluororesin particles may be 1: 3 to 1: 5. When the weight ratio of the template particles to the fluororesin particles is within the above range, the produced film may be more advantageous to exhibit superhydrophobic property

The size of the template particles can be appropriately selected in consideration of the pore size of the fluororesin foam to be produced. In one example, the size of the template particles may be 30 nm to 10 탆. When the size of the template particles is within the above range, the produced film may be more advantageous to exhibit supersensitivity.

The kind of the template particles can be suitably selected in consideration of the object of the present application. In one example, the template particles may comprise NaCl, CaCo ₃ , Na ₂ CO ₃ , Na ₂ SO ₄ , KCl, CaCl ₂ , MgCl ₂ or SiO ₂ . Such template particles are not deformed at the molding temperature of the fluororesin, but may be advantageous in that they can be easily dissolved by a solvent.

The fluororesin particles can be suitably selected in consideration of the object of the present application. In one example, the fluororesin particles may comprise polytetrafluoroethylene, perfluoroalkoxy-polytetrafluoroethylene copolymer, fluorinated ethylene propylene or ethylene-tetrafluoroethylene. These fluororesin particles may be advantageous in terms of stability at high temperatures, acids, fumes, organic solvents and the like.

The residual solvent may be suitably selected in consideration of the object of the present application. In one example, an organic solvent may be used as the residual solvent. As the organic solvent, acetone, methyl ethyl ketone, n-hexane or cyclohexane may be used.

The coating thickness of the mixture of the first step may be appropriately selected in consideration of the thickness of the fluoropolymer foam to be produced. In one example, the coating thickness of the mixture of the first step may be 10 [mu] m to 1 mm. When the coating thickness is within the above range, the produced film may be more advantageous to exhibit supersensitivity. In addition, when the coating thickness is too thick, cracks tend to occur as the solvent evaporates, so it may be advantageous to apply the coating within the thickness range described above.

The substrate to which the mixture of the first step is applied may be a known substrate used in the production of the film. As the substrate, an inorganic film such as glass or silicon, a plastic film, or the like can be used. Alternatively, the substrate may be an object for which the surface is to be modified to superhydrophobicity.

The evaporation of the residual solvent in the second step may be carried out by natural evaporation at room temperature. The natural evaporation can be carried out for 1 to 20 hours. As used herein, ambient temperature may mean a temperature in the range of about 10 < 0 > C to 40 < 0 > C. The higher the evaporation rate, the greater the possibility of cracking of the fluororesin foam, so it may be advantageous to evaporate at the above temperature range.

The heating of the mixture in the third step may be carried out at a temperature of 300 ° C to 400 ° C for 3 minutes to 30 minutes. The sintering between the fluororesin particles can be effectively induced by heating the mixture within the temperature and time range.

The washing of the template particles in the fourth step can be performed by cooling the mixture at room temperature and then dissolving the template particles in a washing solvent. As the washing solvent, a suitable solvent may be selected to dissolve the template particles. In one example, water or acidic water may be used as the washing solvent.

The superhydrophobic film and the manufacturing method thereof of the present application can be applied to all technical fields in which a superhydrophobic film is required. For example, the superhydrophobic film and process for making the same of the present application can be used for self-cleaning, antifouling, anti-icing, oil-water separation, resistance, and the like.

The present application can provide a supercritical water-repellent film which is stable at a high temperature, an acid, a base and an organic solvent, and a process for producing the same. The superhydrophobic film and the method of manufacturing the same of the present application can be applied to various applications such as self-cleaning, antifouling, anti-icing, oil-water separation, corrosion resistance, And can be applied to various fields.

1 is a schematic diagram of a superhydrophobic film of the present application.
Fig. 2 is a schematic view for explaining the method for producing the superhydrophobic film of the present application. Fig.
3 is an SEM image of NaCl particles of Example 1. Fig.
4 is an SEM image of the fluororesin foam film of Example 1. Fig.
5 is an SEM image of CaCO ₃ particles of Example 2. Fig.
6 is an SEM image of the fluororesin foam film of Example 2. Fig.
7 is an SEM image of the fluororesin foam film of Example 3. Fig.
8 is an SEM image of the fluororesin foam film of Example 4. Fig.
9 is an SEM image of the fluororesin foam film of Example 5. Fig.
10 is an SEM image of the fluororesin film of Comparative Example 1. Fig.
11 is a contact angle measurement image of the fluororesin foam film of Example 1. Fig.
12 is an image of the contact angle measurement of the fluororesin foam film of Comparative Example 1. Fig.

Hereinafter, specific details for carrying out the ultra-hydrophobic film of the present application and the production method thereof will be described with reference to the examples, but the scope of the present application is not limited to the following contents.

Example  One

The salt was ball-milled with 8 mm zirconia beads for 24 hours to obtain salt particles having a size of 500 nm to 4 탆 (FIG. 3). A mixture obtained by mixing 10 phr (parts per hundred) of the above-mentioned salt particles and 10 phr of Teflon powder in 80 phr of acetone was applied on the substrate. Next, the mixture was dried by evaporating acetone. The dried Teflon / salt mixture is heated at 300 ° C to 400 ° C for 3 minutes to 30 minutes to induce sintering between Teflon powders. Next, the mixture was cooled to room temperature, and then the salt particles were washed with water to prepare a fluororesin foam film. An SEM image of the film of Example 1 is shown in Fig. The fluororesin foam film of Example 1 has an open cell structure with a thickness of 30 탆, a pore size of 1 탆 to 5 탆, and a pore volume ratio of 50%.

Example  2

CaCO ₃ The powder was ball-milled with 8 mm zirconia beads for 24 hours to obtain CaCO ₃ particles (FIG. 5) mixed with the sizes of 30 nm to 50 nm, 100 nm to 500 nm and 1 μm to 2 μm. A mixture of 10 phr of the CaCO ₃ particles and 10 phr of Teflon powder in 80 phr of acetone was applied to the substrate. The mixture was then dried by evaporating the acetone. The dried Teflon / CaCO ₃ mixture is heated at 300 ° C to 400 ° C for 3 minutes to 30 minutes to induce sintering between Teflon powders. Next, the mixture was cooled to room temperature, and then CaCO ₃ particles were washed with acidic water to prepare a fluororesin foam film. An SEM image of the film of Example 2 is shown in Fig. The fluororesin foam film of Example 2 has an open cell structure with a thickness of 30 탆, a pore size of 1 탆 to 5 탆, and a pore volume ratio of 55%. An SEM image of the film of Example 2 is shown in Fig.

Example  3

A fluororesin foam film was prepared in the same manner as in Example 1 except that a mixture of 10 phr of Teflon powder and 20 phr of CaCO ₃ particles in 120 phr of acetone was used. An SEM image of the film of Example 3 is shown in Fig. The fluororesin foam film of Example 3 has an open cell structure with a thickness of 30 탆, a pore size of 50 nm to 2 탆, and a pore volume ratio of 62%.

Example  4

A fluororesin foam film was prepared in the same manner as in Example 1, except that a mixture of 10 phr of Teflon powder and 30 phr of CaCO ₃ particles in 160 phr of acetone was used. An SEM image of the film of Example 4 is shown in Fig. The fluororesin foam film of Example 4 had an open cell structure with a thickness of 30 탆, a pore size of 50 nm to 2 탆, and a pore volume ratio of 71%.

Example  5

A fluororesin foam film was prepared in the same manner as in Example 1, except that a mixture of 10 phr of Teflon powder and 40 phr of CaCO ₃ particles in 200 phr of acetone was used. An SEM image of the film of Example 5 is shown in Fig. The fluororesin foam film of Example 5 had an open cell structure with a thickness of 30 탆, a pore size of 50 nm to 2 탆, and a pore volume ratio of 77%.

Comparative Example  One

A mixture of 20 phr of Teflon powder and 80 phr of acetone was applied to the substrate. Next, the mixture was dried by evaporating acetone. The dried Teflon is heated at 300 to 400 ° C for 3 to 30 minutes to induce sintering among the Teflon powder. Next, after the mixture was cooled to room temperature, the salt particles were washed with water to prepare a fluororesin film. An SEM image of the film of Comparative Example 1 is shown in Fig. The film of Comparative Example 1 had a closed cell structure with a thickness of 30 mu m, a pore size of 50 nm to 2 mu m, and a volume ratio of pores of 5%.

Experimental Example  One

The contact angle was measured with respect to the fluororesin film. The contact angle was measured by a droplet type analysis method using a DSA100 instrument of Kruss. The contact angles with respect to water for Example 1 and Comparative Example 1 were measured, the results are shown in Table 1, and the contact angle measurement images are shown in FIGS. 11 and 12. FIG. As a result of the experiment, it can be seen that the fluororesin film of the same material can change the contact angle to water by changing the surface roughness by forming pores. The contact angles of water and acrylic acid for each of Examples 2 to 5 were measured and the results are shown in Table 2 below. As a result of the experiment, it can be seen that the contact angle can be changed by changing the content ratio of the fluororesin particles and the template particles, that is, by changing the volume ratio of the pores of the fluororesin foam.

Contact angle (°) Example 1 Comparative Example 1 water 145.3 124.8

Contact angle (°) Example 2 Example 3 Example 4 Example 5 water 150.6 ± 1.8 151.2 ± 0.4 154.1 ± 0.6 149.4 ± 1.3 Acrylic acid 132.7 ± 3.1 135.2 ± 1.0 138.2 ± 0.5 138.4 ± 1.0

1: Fluorine resin
2: Groundwork
3: Template particles
4: Fluorine resin particle
5: residual solvent
6: substrate

Claims (16)

A superhydrophobic film comprising a fluororesin foam formed in an open cell structure having a pore size of 50 nm to 5 占 퐉. The method according to claim 1,
Wherein the pores of the open cell structure are connected to each other. The method according to claim 1,
Wherein the volume ratio of the pores is 10% to 90%. The method according to claim 1,
Wherein the fluororesin comprises polytetrafluoroethylene, a perfluoroalkoxy-polytetrafluoroethylene copolymer, fluorinated ethylene propylene or ethylene-tetrafluoroethylene. The method according to claim 1,
Wherein the fluororesin foam has a thickness of 10 mu m to 1000 mu m. The method according to claim 1,
Wherein the contact angle of the super-hydrophobic film with respect to water is not less than 140 degrees. A first step of applying on a substrate a mixture comprising template particles having a size of 0.03 mu m to 10 mu m, fluororesin particles and a residual solvent;
A second step of evaporating the remaining solvent in the coated mixture to dry it;
A third step of heating the dried mixture to sinter the fluororesin particles; And
And a fourth step of washing the template particles in the sintered mixture to form a fluororesin foam. 8. The method of claim 7,
Wherein the mixture of the first step comprises fluororesin particles and template particles in a weight ratio of 10: 1 to 1:10. 8. The method of claim 7,
Wherein the template particles comprise NaCl, CaCo ₃ , Na ₂ CO ₃ , Na ₂ SO ₄ , KCl, CaCl ₂ , MgCl ₂ or SiO ₂ . 8. The method of claim 7,
Wherein the fluororesin particles comprise polytetrafluoroethylene, a perfluoroalkoxy-polytetrafluoroethylene copolymer, fluorinated ethylene propylene or ethylene-tetrafluoroethylene. 8. The method of claim 7,
Wherein the residual solvent comprises an organic solvent comprising acetone, methyl ethyl ketone, n-hexane or cyclohexane. 8. The method of claim 7,
Wherein the coating thickness of the mixture in the first step is 10 占 퐉 to 1 mm. 8. The method of claim 7,
Wherein the evaporation of the residual solvent in the second step is carried out by natural evaporation at room temperature for 1 to 20 hours. 8. The method of claim 7,
Wherein the heating of the mixture in the third step is carried out at a temperature of 300 ° C to 400 ° C for 3 minutes to 30 minutes. 8. The method of claim 7,
Wherein the washing of the template particles in the fourth step is carried out by cooling the mixture at room temperature and then dissolving the template particles in a washing solvent. 8. The method of claim 7,
Wherein the cleaning solvent comprises water or acidic water.

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