KR20110090150A - Laminate having superhydrophobic surface and process for preparing the same - Google Patents

Abstract

PURPOSE: A laminate having the superhydrophobic surface, and a manufacturing method thereof are provided to simply and economically obtain the superhydrophobic surface by acidifying, metal depositing, and hydrophobic material coating processes of a substrate. CONSTITUTION: A laminate having the superhydrophobic surface comprises the following: a substrate with the rough surface; a metal deposition layer formed on the rough surface of the substrate; and a hydrophobic coating layer formed on the upper side of the metal deposition layer. A manufacturing method of the laminate comprises the following steps: acid-processing the substrate to obtain the rough surface; depositing metals on the rough surface of the substrate; and coating a hydrophobic material on the metal deposition layer.

Description

Laminate having superhydrophobic surface and manufacturing method thereof

The present invention relates to a laminate having a superhydrophobic surface and a method for producing the same, and more particularly, to a laminate having a superhydrophobic surface by acid treatment of a substrate, metal deposition, and coating of a hydrophobic material, and a method for manufacturing the same.

Recently, technology based on natural imitation has attracted considerable attention. Lotus leaves are known for their self-cleaning effects. Micrometer scale papillae structure and epidermal wax on lotus leaves contribute to self-cleaning effects. Similar to the self-cleaning properties of lotus leaves, the wettability of solid surfaces is of great interest in everyday life and industry. Wetting is controlled by the surface geometry and low surface energy material coating. The superhydrophobic surface satisfies a water contact angle of 150 ° or more and a sliding angle of 10 ° or less. On superhydrophobic surfaces, water droplets are completely spherical in shape and easily roll off to remove accumulated contaminants. This superhydrophobic surface protects the material from contamination, fog and snow accumulation.

Material coatings with low surface energy on flat surfaces have a water contact angle of 120 ° or less. Thus, in order to obtain a high contact angle, it means that the flat surface must be deformed into a rough surface. Many methods have been reported for constructing micro- and nanostructures on surfaces. For example, sol-gel methods, anodic oxidation and plasma treatment, fine preparation using photoetching, solidification of alkylketene dimers, and application of polymers have been used to obtain superhydrophobic surfaces. The presence of micrometer and nanometer scale structures on the surface involves the capture of large amounts of air. This causes a reduction in the contact area between water and the solid surface. Material coatings with low surface energy along with micro- and nanostructures contribute to the superhydrophobicity of the surface. Compounds containing fluorine have been conventionally coated on solid materials to produce artificial superhydrophobic surfaces. Recently, self-assembly of n-alkanoic acid on metal surfaces has been used to produce superhydrophobic surfaces. Au clusters on Indium Tin Oxide (ITO) glass substrates were modified with n-dodecanethiol to obtain a water contact angle of 173 °. A series of n-alkanoic acids have been used to make superhydrophobic surfaces. Depending on the chain length of n-alkanoic acid, the contact angle on the flat surface changed from 68 ° to 113 °. Wet chemical etch surfaces of aluminum alloys were treated with stearic acid and N, N'-dicyclohexylcarbodiimide (DCCD) to obtain superhydrophobic surfaces. In addition, superhydrophobic surfaces of polyethyleneimine-coated aluminum wafers were obtained by reaction with stearic acid and DCCD. DCCD was used as a dehydrating agent to form ester bonds or amide bonds.

However, most methods for producing superhydrophobic surfaces require the use of complex or special equipment.

Accordingly, it is an object of the present invention to provide a method which can produce a laminate having a superhydrophobic surface simply and inexpensively.

Another object of the present invention is to provide a laminate having an excellent superhydrophobic surface and in particular having a superhydrophobic surface useful for removing condensate in air conditioners.

The present invention to achieve the above object, the step of treating the substrate with an acid to form a substrate having a rough surface; Depositing a metal on the surface of the substrate having the rough surface to form a metal deposition layer; And coating a hydrophobic material on the metal deposition layer to form a hydrophobic coating layer.

The superhydrophobic surface of the laminate according to the invention exhibits excellent superhydrophobicity by having a water contact angle of at least 120 ° or more, in particular 140 ° or more.

In the present invention, the metal deposition layer has a porous structure by metal particles of 1 to 100 μm, and the hydrophobic coating layer is formed by self-assembly of hydrophobic material on the metal deposition layer, thereby exhibiting excellent superhydrophobicity.

In the present invention, the substrate may be made of a metal, an inorganic material, and the like, among which the metal may use Mg, Fe, Ni, Cu, Al and the like. Mg is particularly preferred as a substrate because Mg is an ultralight metal and can achieve the optimum form required for the deposition of the metal upon pretreatment of the surface with acid.

In the present invention, the metal deposition layer may be made of metals such as Ni, Cu, and Al. Of these, Ni and Cu are particularly preferred, since Ni ⁺² and Cu ⁺² ions can be reduced under mild conditions.

In the present invention, the hydrophobic coating layer may be composed of 4 to 32 carbon atoms and perfluorodecanoic acid. As fatty acids, for example, saturated fatty acids such as stearic acid and unsaturated fatty acids such as oleic acid can be used. Of these, stearic acid is particularly preferred because stearic acid is optimal for forming self-assembled molecular layers and can achieve high water contact angles after formation on the surface.

In the present invention, various acids such as HCl, H ₂ SO ₄ and HNO ₃ may be used as the acid. HCl is preferable because sulfuric acid and nitric acid excessively corrode the surface with a strong acid.

In addition, the present invention is a substrate having a rough surface; A metal deposition layer formed on the rough surface of the substrate; And a hydrophobic coating layer formed on the metal deposition layer.

The laminate having a superhydrophobic surface according to the present invention and a method for manufacturing the same may be applied to a refrigerator, an air conditioner, a building or a transportation device.

The present invention provides a simple and inexpensive method for producing superhydrophobic surfaces by acid treatment of substrates, metal deposition, and hydrophobic material coatings.

The superhydrophobic surface of the laminate according to the invention exhibits excellent superhydrophobicity by having a water contact angle of at least 120 ° or more, in particular 140 ° or more.

FIG. 1 shows optical images of water droplets on the Mg surface treated with HCl, Ni deposited and stearic acid coated (left photograph), and profiles of water droplets on the Mg surface with a contact angle of 144.5 ° (right photograph).
2 is an SEM image of Ni on an Mg plate, the right side being an enlarged image (1 μm) on the left side.
FIG. 3 is an SEM image of stearic acid coated on Ni crystals deposited on an Mg plate, and the right side is an enlarged image (1 μm) on the left side.
4 is an SEM image of Cu crystal deposited on an Mg plate, the right side is an enlarged image (1 μm) on the left.
FIG. 5 is an SEM image of stearic acid coated on Cu crystals deposited on an Mg plate, the right side being an enlarged image (1 μm) on the left.
6 is a profile (water contact angle) picture of water droplets on the surface of Mg, the first picture is untreated magnesium (Comparative Example 1), the second picture is treated with 5% HCl only (Comparative Example 2), and the third The photo shows only the deposition of Cu crystals (Comparative Example 3), and the fourth photo consists of all HCl treatment, Cu deposition and stearic acid coating (Example 2).
7 shows the XPS pattern of stearic acid coating on Mg surface.
FIG. 8 shows the relationship between water droplet pH and water contact angle on the superhydrophobic surface of Mg blocks.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The laminate having a superhydrophobic surface of the present invention is composed of a substrate having a rough surface, a metal deposition layer formed on the rough surface of the substrate, and a hydrophobic coating layer formed on the metal deposition layer.

The base material is made of metal, inorganic material, and the like. Various metal materials and / or alloys thereof, such as Mg, Fe, Ni, Cu, and Al, may be used as the metal, and Mg is particularly preferable. As the inorganic material, various inorganic materials such as glass and silicon wafers can be used.

The substrate is usually in the form of a plate, but a critical form is also possible, and the form is not particularly limited.

The substrate is treated with an acid to have a rough surface, which serves to form micrometer and nanometer scale structures that serve to increase superhydrophobicity.

The metal deposition layer may be made of Ni, Cu, Al, and the like, with Ni and Cu being particularly preferred.

It is preferable that the thickness of a metal deposition layer is 10-100 micrometers. There is a sufficient amount of air in the space between the crystal grains deposited within this thickness range to minimize the contact surface of the water droplets.

The metal deposition layer has a porous structure with metal particles of 1 to 100 μm on the surface. The metal cluster deposited on the surface has a nanoscale protrusion structure. Micrometer and nanometer scale structures and cavities on the surface play an important role in trapping air. The rough microstructure of the surface is important for producing hydrophobic surfaces.

The hydrophobic coating layer may be composed of fatty acids having 4 to 32 carbon atoms, perfluorodecanoic acid, and the like. As the fatty acid, for example, saturated fatty acids such as stearic acid, unsaturated fatty acids such as oleic acid can be used, and stearic acid is particularly preferable.

The thickness of the hydrophobic coating layer is determined by the length of the fatty acids used, in particular the molecular length of stearic acid being most preferred.

The hydrophobic coating layer is formed by self-assembly of hydrophobic material on the metal deposition layer, thereby exhibiting excellent superhydrophobicity. Self-assembly of hydrophobic materials on metal clusters greatly reduces surface free energy, thereby greatly increasing water contact angle. In addition to micrometer and nanometer scale structures, low surface energy materials are important factors in obtaining superhydrophobic surfaces.

The method for producing a laminate having a superhydrophobic surface according to the present invention is as follows.

First, the substrate is washed with acetone, distilled water and the like and then dried.

The substrate is then treated with acid to form a substrate with a rough surface. Acid treatment can be accomplished by immersing the substrate in an acid solution. When the substrate is treated with an acid, a rough surface having a fine concavo-convex structure is formed on the surface of the substrate. As the acid, HCl, H ₂ SO ₄ and HNO ₃ may be used, with HCl being particularly preferred. After acid treatment, the mixture is washed with distilled water and then dried.

Next, metal is deposited on the surface of the substrate having the rough surface to form a metal deposition layer. Deposition can be accomplished by immersing the substrate in a solution comprising a metal salt and a reducing agent. The reducing agent serves to reduce the metal ions of the metal salts and deposit them on the surface of the substrate. As the metal salt, for example, sulfates such as NiSO ₄ and CuSO ₄ can be used. N ₂ H ₄ or the like can be used as the reducing agent. Dry after deposition.

Next, a hydrophobic material is coated on the metal deposition layer to form a hydrophobic coating layer. Coating can be accomplished by immersing the substrate in a solution comprising a hydrophobic material. Dry after coating.

As such, by acid treatment and metal deposition of substrates providing micro / nano structures, and by hydrophobic material coatings providing low surface energy, superhydrophobic surfaces with a water contact angle of 140 ° or more can be obtained in a simple and inexpensive manner. have.

The laminate having a superhydrophobic surface of the present invention and a method of manufacturing the same may increase efficiency by easily removing condensate when applied to a refrigerator and an air conditioner (home and automobile). Specifically, by changing the metal surface to a superhydrophobic surface to easily remove the moisture hit the evaporator of the air conditioner, it is possible to increase the efficiency of the air conditioner, thereby reducing power consumption and electricity bills. Rapid removal of condensate using the Lotus effect provides excellent durability for long lasting durability and clean appearance through corrosion protection of the evaporator surface. The removal of these droplets has the function of increasing the electrical efficiency of the device.

In addition, the laminate having the superhydrophobic surface of the present invention and a method of manufacturing the same may contribute to preservation of the building from moisture when applied to the building. In addition, when applied to a transport device (eg, airplane, car), it is possible to increase the function of the operation. Since the present invention uses a method of mechanically removing condensate when used in automobiles, the use of the present invention can increase space utilization by removing unnecessary machines.

Hereinafter, an Example is given and this invention is demonstrated in detail. However, the protection scope of the present invention is not limited by the following examples.

Example 1

A laminate having a superhydrophobic surface was prepared by the following procedure. Magnesium metal plate in the form of a substrate was used, HCl was used as an acid, Ni was used as a metal for metal deposition, and stearic acid was used as a hydrophobic material.

(1) substrate cleaning

The magnesium pieces were washed in acetone and then for 5 minutes in distilled water in an ultrasonic bath.

(2) acid treatment

After drying, the magnesium pieces were soaked in 5% HCl solution for 2 minutes, washed with distilled water, and then dried at 80 ° C. for 1 hour.

(3) metal deposition

The acid treated magnesium pieces were soaked in a mixed solution for metal deposition (1.3 g of NiSO ₄ .6H ₂ O and 0.62 g of N ₂ H _{4 in} 100 ml of H ₂ O) at 80 ° C. for 4 hours, and then dried at room temperature overnight.

(4) hydrophobic coating

The metal-deposited magnesium pieces were soaked in an aqueous solution of stearic acid (1 g in 100 ml of distilled water) for 50 minutes and then dried at room temperature for 24 hours.

[Example 2]

A Cu-deposited superhydrophobic magnesium plate was prepared in the same manner as in Example 1 except using Cu as the deposited metal. The mixed solution for metal deposition was composed of 1.3 g of CuSO ₄ 5H ₂ O and 0.62 g of N ₂ H _{4 in} 100 ml of H ₂ O.

Comparative Example 1

Untreated magnesium.

Comparative Example 2

Magnesium was treated with acid only with 5% HCl.

Comparative Example 3

Only Cu was deposited on magnesium.

[Test Example]

Geometric structure

In order to investigate the geometric nano- and microstructures of the superhydrophobic surface, a scanning electron microscope (SEM) was used.

1 shows water droplets on a Ni-deposited magnesium plate modified with stearic acid. The left picture is the optical image of the water droplets on the Mg surface treated with HCl, Ni deposited and stearic acid coated, and the right picture shows the profile of the water droplets on the Mg surface with a contact angle of 144.5 °.

FIG. 2 is an SEM image of Ni on an Mg plate, the right side is an enlarged image (1 μm) on the left side, and FIG. 3 is an SEM image of stearic acid coated on a Ni crystal deposited on an Mg plate, and the right image is an enlarged image on the left side ( 1 μm), FIG. 4 is an SEM image of Cu crystals deposited on an Mg plate, the right side is an enlarged image (1 μm) on the left side, and FIG. 5 is an SEM image of stearic acid coated on Cu crystals deposited on an Mg plate. , The right side is an enlarged image (1 μm) on the left side.

2-5 show typical forms of superhydrophobic surfaces of Ni or Cu-deposited magnesium plates, respectively. Porous structures and Ni or Cu particles (1-100 μm in size) were observed on the surface. Metal clusters deposited on the surface exhibited an interesting structure with nanoscale protrusions. Micrometer and nanometer-scale structures and cavities on the surface have played an important role in capturing air that acts as the basis for water. Low surface energy materials as well as the rough microstructure of the surface are important for making hydrophobic surfaces.

Number of contact angle

The male contact angle was measured using a contact angle meter.

6 is a profile (water contact angle) picture of water droplets on the surface of Mg, the first picture is untreated magnesium (Comparative Example 1), the second picture is treated with 5% HCl only (Comparative Example 2), and the third The photo shows only the deposition of Cu crystals (Comparative Example 3), and the fourth photo consists of all HCl treatment, Cu deposition and stearic acid coating (Example 2).

As can be seen in FIG. 6, the magnesium surface modified with 5% HCl was still a hydrophilic surface with a water contact angle of 20.4 ° (Comparative Example 2). Without stearic acid coating, the water contact angle of the Cu-deposited magnesium surface was 34.4 ° (Comparative Example 3). The Cu-deposited magnesium surface modified with stearic acid was a superhydrophobic surface with a water contact angle of 142.5 °.

It is possible by lithography to raise the contact angle of water by more than 150 ° with the nanostructure alone. However, since the change in contact angle of water is very large only by etching or deposition of metal crystals, coating of nanostructures and low surface energy materials must be performed simultaneously.

As such, an important change in the water contact angle is that self-assembly of stearic acid on metal clusters greatly reduced surface free energy. There was no obvious change in roughness and structure after stearic acid treatment. These results indicate that micrometer- and nanometer-scale structures and low surface energy materials are important factors for obtaining superhydrophobic surfaces.

XPS Pattern

Stearic acid was coated on the magnesium surface by X-ray photoelectron spectroscopy (XPS).

7 shows the XPS pattern of stearic acid coating on the Mg surface, where XPS signals of C and O were observed on the hydrophobic metal surface. This indicates that the metal surface is covered with stearic acid.

pH influence

It was investigated whether the superhydrophobicity of the magnesium surface changes while changing the pH of the aqueous solution.

8 shows the relationship between pH and water contact angle on the superhydrophobic magnesium surface. The contact angle on the magnesium surface was 124.5 ° to 144.5 ° when the pH varied from 1 to 14. Based on the observed changes in the water contact angle of the surface, it can be concluded that the pH of the aqueous solution has little effect on the superhydrophobicity of the metal surface. The superhydrophobic surface was stable over a wide range of pH values.

In conclusion, a simple and inexpensive method of producing superhydrophobic surfaces of magnesium by metal deposition and stearic acid coatings has been developed. Superhydrophobic surfaces were prepared on magnesium by nickel or copper deposition and stearic acid surface coating. The prepared surface was stable against acidic and basic solutions.

Claims (13)

Treating the substrate with an acid to form a substrate having a rough surface;
Depositing a metal on the surface of the substrate having the rough surface to form a metal deposition layer; And
Coating a hydrophobic material on the metal deposition layer to form a hydrophobic coating layer
A method for producing a laminate having a superhydrophobic surface. The method of manufacturing a laminate having a superhydrophobic surface according to claim 1, wherein the water contact angle of the superhydrophobic surface is 120 ° to 180 °. The method of manufacturing a laminate having a superhydrophobic surface according to claim 2, wherein the water contact angle of the superhydrophobic surface is 140 ° to 160 °. The method for producing a laminate having a superhydrophobic surface according to claim 1, wherein the metal deposition layer has a porous structure with metal particles of 1 to 100 m. The method of claim 1, wherein the hydrophobic coating layer is formed by self-assembly of hydrophobic material on the metal deposition layer. The method for producing a laminate having a superhydrophobic surface according to claim 1, wherein the substrate is made of one or more selected from metals and inorganics. The method for producing a laminate having a superhydrophobic surface according to claim 6, wherein the metal is at least one selected from Mg, Fe, Ni, Cu, and Al. The method for producing a laminate having a superhydrophobic surface according to claim 1, wherein the metal deposition layer is formed of at least one selected from Ni, Cu, and Al. The method for producing a laminate having a superhydrophobic surface according to claim 1, wherein the hydrophobic coating layer comprises at least one selected from fatty acids having 4 to 32 carbon atoms and perfluorodecanoic acid. The method for producing a laminate having a superhydrophobic surface according to claim 9, wherein the fatty acid is stearic acid. The method for producing a laminate having a superhydrophobic surface according to claim 1, wherein the acid is at least one selected from HCl, H ₂ SO ₄ and HNO ₃ . The method of manufacturing a laminate having a superhydrophobic surface according to claim 1, wherein the laminate is used in a refrigerator, an air conditioner, a building, or a transportation device. A substrate having a rough surface treated with an acid;
A metal deposition layer formed on the rough surface of the substrate; And
A hydrophobic coating layer formed on top of the metal deposition layer
Laminates having a superhydrophobic surface.

Images