KR102308050B1 - Superhydrophobic surface making method and Superhydrophobic substrate repairing method same using - Google Patents

Abstract

The present invention relates to a superhydrophobic surface making method and a superhydrophobic substrate repairing method using the same. In accordance with the present invention, the superhydrophobic surface making method comprises the following steps of: preparing a substrate; preparing laser; irradiating the laser to the substrate and forming a pattern on a surface of the substrate; coating the substrate with the pattern on the surface with silicon oil; and thermally treating the substrate coated with silicon oil. The present invention is able to coat a substrate with a pattern on a surface formed by irradiating laser, thermally treat the substrate, form a superhydrophobic surface, and reduce the time required for forming the superhydrophobic surface. In addition, the present invention is able to, when the superhydrophobic surface is damaged, apply the coating with silicon oil and the thermal treatment for forming a superhydrophobic surface, and make the superhydrophobic surface as the original status.

Description

Superhydrophobic surface making method and superhydrophobic substrate repair method using same

The present invention relates to a method for manufacturing a superhydrophobic surface and a method for repairing a superhydrophobic substrate using the same, and more particularly, it is possible to easily manufacture a surface having superhydrophobicity on a substrate, and if the superhydrophobicity of the substrate surface is damaged, it can be repaired. It relates to a method for producing a superhydrophobic surface that can be used and a method for repairing a superhydrophobic substrate using the same.

A surface with a contact angle of 150° or more with water droplets and a sliding angle of 10° or less is called a superhydrophobic surface. These surfaces have extremely water repellent properties and very low contact angle hysteresis because the area of contact between the actual solid surface and water is very small. Studies on various applications have been conducted using these properties.

There have been several techniques for fabricating superhydrophobic surfaces.

First, a method of forming a superhydrophobic pattern on a surface using a laser may be exemplified. There are two main methods for producing superhydrophobicity through pulsed laser.

① After processing the surface of the substrate using a laser, there is a method of coating toxic chemicals, and ② Method of processing the substrate surface using a laser and then performing room temperature/heat treatment/vacuum treatment.

After laser processing, the method of coating a chemical is not eco-friendly and has a problem in that it requires a long manufacturing time, such as washing and drying after coating.

In addition, the method of performing room temperature/heat treatment/vacuum treatment after laser processing has the following problems.

That is, there is a problem in that room temperature treatment and heat treatment require several hours to several days. In addition, in the case of vacuum processing, it takes a relatively short time, but due to the nature of the vacuum, a lot of energy is consumed in the use of equipment and the process of holding the vacuum, which is not economical.

On the other hand, since the superhydrophobic surface completed through a predetermined treatment process has reduced superhydrophobicity due to abrasion and surface damage during use by the user, it is necessary to repair it.

As a prior art for the present invention, Patent Registration No. 10-1449589 can be exemplified.

The present invention is to solve the above problems, and to provide a method for producing a superhydrophobic surface so that a superhydrophobic surface is formed by performing silicone oil coating and heat treatment on a substrate on which a pattern is formed on the surface by laser irradiation. do.

Another object of the present invention is to provide a superhydrophobic substrate repair method capable of repairing superhydrophobicity by applying to a substrate having reduced superhydrophobicity after being used for a certain period of time or more.

In order to achieve the above object, the present invention comprises the steps of preparing a substrate; preparing the laser; forming a pattern on a surface of the substrate by irradiating the laser onto the substrate; coating the substrate with the pattern on its surface with silicone oil; and heat-treating the silicon oil-coated substrate.

The substrate may include aluminum, copper, titanium, stainless steel, ceramic-glass, sapphire and titanium dioxide.

The step size of the pattern may be 100 to 400 μm, and the scanning speed of the laser may be 5 to 10 mm/s.

The step size of the pattern may be 100 to 200 μm, and the scanning speed of the laser may be 50 mm/s or less.

The step size of the pattern may be 100 μm or less, and the scanning speed of the laser may be 100 mm/s or less.

The concentration of the silicone oil to be coated on the substrate may be 0.1 to 100% by volume.

The heat treatment may be performed at a temperature of 50 to 250° C. for 5 to 10 minutes.

In order to achieve the above object, the present invention provides a method for repairing a superhydrophobic substrate having a superhydrophobic surface prepared by the superhydrophobic surface preparation method of any one of claims 1 to 7, wherein the damaged portion of the superhydrophobic surface is It provides a method of repairing a superhydrophobic substrate for repairing the superhydrophobic surface by performing the steps of coating the silicone oil on the surface and heat-treating the superhydrophobic surface.

The present invention as described above, by performing silicone oil coating and heat treatment on a substrate on which a pattern is formed on the surface by laser irradiation to form a superhydrophobic surface, compared to the prior art of forming a superhydrophobic surface using only heat treatment This has the effect of reducing the time and energy required to form the superhydrophobic surface.

In addition, the present invention has the effect of returning the superhydrophobic surface to its original state by applying a silicone oil coating and heat treatment for forming the superhydrophobic surface when the superhydrophobic surface is damaged.

1 is a flowchart showing the configuration of a method for producing a superhydrophobic surface according to the present invention.
2 is a diagram showing the configuration of a laser generator used in the present invention.
3 is a diagram illustrating an example of a superhydrophobic pattern formed on a substrate.
4 is a view illustrating a contact angle and a sliding angle of a substrate on which heat treatment has been performed.
5 is a view for explaining the contact angle according to the supply of silicone oil and whether or not heat treatment.
6 is a graph showing the contact angle and sliding angle of the substrate surface according to the number of times of adhesion and peeling of the adhesive tape.
7 is a graph showing the contact angle and sliding angle of the substrate measured immediately after completion of the substrate and 3 months later.
8 is a table showing the contact angle and the sliding angle according to the material of the substrate.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart showing the configuration of a method for producing a superhydrophobic surface according to the present invention.

Referring to Figure 1, the superhydrophobic surface manufacturing method according to the present invention comprises the steps of preparing a substrate (ST110), preparing a laser (ST120), forming a pattern (ST130), and coating silicone oil ( ST150), and performing a heat treatment step (ST160). In addition, the superhydrophobic surface preparation method according to the present invention further includes a first washing step (ST140) and a second washing step (ST170).

The step of preparing the substrate ( ST110 ) is a step of preparing a substrate, which is an object on which a pattern is to be formed. In this embodiment, an AISI 304 stainless steel sheet (stainless steel 304, iNexus, Inc., Korea) having a thickness of 1 mm and a size of 5x5 mm² is prepared as a substrate. However, the size of the prepared substrate may be variously set according to the needs of the user.

In addition, although stainless steel is used as the substrate in this embodiment, aluminum, copper, titanium, ceramic-glass, sapphire, and titanium dioxide may be used as the substrate.

The step of preparing the laser ( ST120 ) is a step of preparing a laser generator for forming a pattern on the prepared substrate.

2 is a diagram showing the configuration of a laser generator used in the present invention.

Referring to FIG. 2, the laser generator 10 used in the present invention includes a control unit 11 for outputting a laser generation control signal, a laser source 12 which operates according to the control signal of the control unit 11 and outputs a laser, First to third path switching mirrors 13a, 13b, and 13c for switching the laser output from the laser source 12 in a required direction, an attenuator 14, a light diffuser 15, a predetermined It may include a scanning system 16 for irradiating a laser in a required pattern at a predetermined speed with respect to the substrate 1 disposed on the mount 2 .

Since the laser generator 10 shown in FIG. 2 is a well-known technology, a detailed description thereof will be omitted.

In the present embodiment, the laser generator 10 may generate an Nd:YAG 355 nm UV pulse laser, scan the substrate 1 at a predetermined speed, and irradiate the laser.

The step of forming the pattern (ST130) is a step of forming a pattern on the substrate 1 by irradiating the laser output from the laser generator 10 prepared in the step of preparing the laser (ST120) on the substrate 1 . .

3 is a diagram illustrating an example of a pattern formed on a substrate.

Referring to FIG. 3 , it can be seen that a grid-shaped superhydrophobic pattern having a predetermined step size S is formed on the substrate 1 . Although the superhydrophobic pattern in the form of a square having the same length of each side is formed in the drawing, various patterns such as a circle, a star, and a heart may be formed in the shape of the pattern according to the needs of the user.

The specification of the laser generated by the laser generator 10, the laser scan speed, and the step size of the pattern formed on the substrate are as described in [Table 1] below.

Laser power (W) 2 Laser pulse frequency (kHz) 20 Laser pulse period (ns) 20 Laser scan speed (mm/s) 5, 10, 50, 100, 500 Step size of the pattern (μm) 100, 200, 300, 400

As described in [Table 1], the user variously changes the laser scan speed and step size, and forms a pattern on the substrate.

In addition, it is preferable to manufacture four samples for each pattern formed on the substrate and perform various test operations, but the number of samples may be increased or decreased according to the needs of the user.

Step size

Scan speed 100 μm 200 μm 300 μm 400 μm 5 mm/s CA: 173.0°
SA: 3.4° CA: 173.6°
SA: 3.8° CA: 173.7°
SA: 4.1° CA: 173.3°
SA: 4.1° 102.2s 52.1s 36.1s 28.1s 10 mm/s CA: 173.8°
SA: 2.8° CA: 172.9°
SA: 3.1° CA: 172.6°
SA: 2.6° CA: 172.6°
SA: 3.0° 51.2s 26.1s 18.1s 14.1s 50 mm/s CA: 173.2°
SA: 4.2° CA: 172.8°
SA: 6.7° CA: 162.0°
SA: 59.4° CA: 155.3°
SA: 74.2° 10.4s 5.3s 3.7s 2.9s 100 mm/s CA: 169.1°
SA: 8.4° CA: 159.8°
SA: 52.6° CA: 157.2°
SA: 73.5° CA: 148.8°
SA: No 5.3s 2.7s 1.9s 1.5s 500 mm/s CA: 153.8°
SA: No CA: 141.1°
SA: No CA: 138.1°
SA: No CA: 138.5°
SA: No 1.2s 0.6s 0.5s 0.4s

In [Table 2], the values of the contact angle (CA) and sliding angle (SA) of the pattern formed according to the step size and the laser scan speed of the pattern to be formed are described. The numerical values listed below the contact angle and sliding angle indicate the time taken for pattern formation.

Referring to [Table 2], it can be seen that when the pattern having a predetermined step size is formed, the substrate on which the pattern is formed has superhydrophobicity when the laser scan speed is below a certain level.

Therefore, when the user sets the step size to 100 to 400 μm, if the scan speed is maintained at 5 to 10 mm/s, the contact angle is 170 degrees or more, and the sliding angle is 10 degrees or less, so that the substrate has superhydrophobicity. have. In addition, if the user sets the step size to 100 to 200 μm, and maintains the scan speed at 50 mm/s or less, the contact angle is 170 degrees or more, and the sliding angle is 10 degrees or less, so that the substrate has superhydrophobicity. . In addition, if the user sets the step size to 100 μm or less, and maintains the scan speed to 100 mm/s or less, the contact angle is 160 degrees or more, and the sliding angle is 10 degrees or less, so that the substrate has superhydrophobicity.

As described above, the user can appropriately set the step size and scan speed in consideration of the required superhydrophobicity and the speed of manufacturing the superhydrophobic surface.

The first cleaning step ST140 is a step of cleaning the substrate 1 for a predetermined time by supplying isopropyl alcohol (IPA) having a purity of 99.5% or more to the substrate 1 with respect to the substrate on which the pattern is formed. Here, in the first cleaning step ST140, the substrate 1 is immersed in isopropyl alcohol (IPA) and maintained for about 3 minutes. When a predetermined time required to perform the first cleaning step ST140 has elapsed, the substrate 1 is dried in the air.

The step of coating the silicone oil (ST150) is a step of coating the silicone oil on the surface of the substrate 1 on which the superhydrophobic pattern is formed. A method of impregnating the substrate in silicone oil, a method of coating the substrate with silicone oil, or a method of applying silicone oil may be used.

The user supplies a predetermined concentration of silicone oil (KF-96, Shin-Etsu Chemical Co., Ltd., Japan) or isopropyl alcohol and a predetermined concentration of silicone oil to the substrate so that the surface of the substrate 1 is coated with silicone oil. do.

Here, the user changes the concentration of the supplied silicone oil in various ways as shown in Table 3 below and examines the contact angle and sliding angle of the pattern formed on the substrate.

IPA+
0.05 vol% silicone oil IPA+
0.1 vol% silicone oil IPA+
0.2 vol% silicone oil IPA+
0.5 vol% silicone oil Pure
silicone oil CA not uniform 172.0° 173.4° 173.8° 174.5° SA No 3.5° 4.0° 4.0° 3.7°

[Table 3] shows the contact angle and sliding angle when the laser is irradiated at a 10 mm / s laser scan speed and isopropyl alcohol and silicon oil of a predetermined concentration are supplied to a pattern formed on a substrate with a step size of 200 μm.

Referring to [Table 3], it can be seen that the contact angle and sliding angle of the superhydrophobic surface are changed according to the case where only silicone oil is supplied and the case where a predetermined amount of isopropyl alcohol is mixed and supplied with silicone oil.

That is, when only pure silicone oil is supplied, the contact angle is 174.5 degrees and the sliding angle is 3.7 degrees. Thereafter, isopropyl alcohol is mixed with pure silicone oil, and when the mixing amount is increased, the contact angle is gradually decreased.

Here, when the concentration of silicone oil was changed from 0.5 volume % to 0.1 volume %, the contact angle decreased from 173.8 degrees to 172.0 degrees, and the sliding angle was from 4.0 degrees to 3.5 degrees, indicating that the substrate surface had superhydrophobicity. have.

When the mixing amount of isopropyl alcohol is further increased and the concentration of silicone oil is decreased to 0.05% by volume, it can be seen that the contact angle is non-uniform and the sliding angle is not measured, so that the substrate does not have superhydrophobicity.

Therefore, the concentration of the silicone oil to be coated on the substrate 1 is preferably 0.1 to 0.5 volume %.

In the step of performing the heat treatment ( ST160 ), heat treatment is performed on the silicon-coated substrate for a predetermined time to make the substrate superhydrophobic.

Here, the heat treatment is performed by maintaining the substrate for a predetermined time in an oven maintaining a predetermined temperature.

4 is a view showing a contact angle and a sliding angle of a substrate subjected to heat treatment.

4 shows the contact angle and sliding angle formed on the substrate when the substrate supplied with isopropyl alcohol and 0.2 vol% silicone oil was maintained in an oven at 200° C. for a predetermined time.

Referring to FIG. 4 , it can be seen that when the heat treatment time lasted 5 minutes or more, the contact angle was 160 degrees or more, and the sliding angle was 10 degrees or less.

In this case, it can be seen that the contact angle is the maximum based on the heat treatment time of 10 minutes. In addition, it can be seen that when the heat treatment time elapses more than 5 minutes, the sliding angle gradually decreases.

Therefore, the heat treatment performed on the silicon oil-coated substrate is preferably performed for 5 to 10 minutes.

On the other hand, after the heat treatment of the substrate is performed, it is preferable that the second cleaning step (ST170) is performed.

In the second cleaning step (ST170), a predetermined ultrasonic wave is irradiated to the substrate 1 on which the heat treatment has been completed, so that the surface of the substrate 1 is cleaned.

The second washing step ST170 is performed as follows.

First, the substrate 1 is placed in an ultrasonic bath having a predetermined size, pure isopropyl alcohol (purity of 99.5% or more) is supplied, and ultrasonic waves are irradiated to the substrate 1 for 10 minutes. Remove the silicone oil and dust remaining on the phase. At this time, the substrate 1 is maintained in a state immersed in isopropyl alcohol.

The finished substrate is stored at room temperature in a predetermined place for future work.

The superhydrophobicity of the substrate subjected to the above process will be examined.

For the patterned substrates, field emission scanning electron microscopy (FE-SEM, JSM-6500F, Jeol Ltd., Japan) and energy dispersive X-ray spectroscopy (EDS, JSM-6500F, Jeol Ltd., Japan) were used to examine the patterned substrates. The sample surface was evaluated.

In addition, after positioning a droplet in a volume of 10 μL against the patterned substrate surface, Fourier-transform infrared spectroscopy (FT-IR, Varian 670-IR, Varian Inc., USA) and X-ray diffraction (XRD, Ultima IV) , Rigaku, Japan) and surface morphology and chemical composition. Wettability of the substrate was evaluated by measuring the contact angle and sliding angle using a contact angle measuring device (Smartdrop SDLab-200TEZD, FemtoFab, Korea).

5 is a view for explaining a contact angle according to the supply of silicone oil and whether heat treatment is performed.

5A shows the contact angle of the substrate prepared in the step of preparing the substrate (ST110). The contact angle measured in FIG. 5 a is 70 degrees.

5B is a contact angle of a substrate on which a pattern is formed by a laser, and the contact angle measured in FIG. 5B is 35 degrees.

5C is a view showing a contact angle of a substrate coated with silicon oil after pattern formation by a laser, and the contact angle is 65 degrees.

FIG. 5D is a view showing a contact angle of a substrate on which only heat treatment is performed, and the contact angle is 88 degrees.

5E is a substrate that has been coated with silicone oil and heat treated, and the contact angle is 100 degrees.

5f shows a substrate that has been subjected to laser irradiation, silicone oil coating, and heat treatment, and it can be seen that the contact angle is 173 degrees.

Therefore, it can be seen that laser irradiation, silicone oil coating, and heat treatment are required to form a superhydrophobic surface on the substrate.

The durability of the superhydrophobicity is measured by the following method with respect to the substrate on which the superhydrophobicity is formed by performing the above process.

The user prepares a predetermined number of each of a substrate on which only a heat treatment is performed without silicon oil coating after pattern formation by a laser, and a substrate on which a heat treatment is performed after pattern formation by a laser and coating a silicone oil with silicon oil.

Then, the user prepares a predetermined adhesive tape, and then uses it to test the durability of the superhydrophobic surface as follows. Here, the prepared adhesive tape is a commercially available tape as an inspection tape for a coating film.

The user attaches the adhesive tape to the surface of the substrate having superhydrophobicity. At this time, it is preferable to apply a pressure of about 25 kPa to the adhesive tape so that the adhesive tape is uniformly adhered.

The user peels the adhesive tape adhered to the substrate 1 from the substrate 1 , and then performs a process of re-adhesive it a plurality of times, and then measures the superhydrophobic property.

6 is a graph showing the contact angle and sliding angle of the substrate surface according to the number of times of adhesion and peeling of the adhesive tape.

6A is a graph showing the contact angle and sliding angle of the substrate only for heat treatment for 12 hours. According to a of FIG. 6, when the number of times of adhesion and peeling of the tape reaches 10, the contact angle is lowered to less than 160 degrees, and it can be seen that the sliding angle exceeds 50 degrees.

6B is a graph showing the contact angle and sliding angle of a substrate coated with silicone oil and subjected to heat treatment for 10 minutes.

According to FIG. 6B , it can be seen that the contact angle is maintained at 160 degrees even when the number of times of adhesion and peeling of the tape is 10 or more, and the sliding angle is less than 50 degrees even when the number of times of adhesion and peeling of the tape is reached 100 times.

Therefore, it can be seen through the tape test as described above that the durability of the superhydrophobic properties of the substrate heat-treated in the silicone oil-coated state is higher than the durability of the super-hydrophobic properties of the substrate on which only the conventional heat treatment is performed.

7 is a graph showing the contact angle and sliding angle of the substrate measured immediately after the completion of the substrate and after 3 months.

Referring to FIG. 7A , the contact angle of the substrate immediately after performing the heat treatment of the substrate on which the pattern having the step size of 100, 200, 300, and 400 μm is formed, respectively, and the contact angle after 3 months after the heat treatment are shown.

In addition, referring to FIG. 7B , the contact angle of the substrate immediately after performing the heat treatment of the substrate on which the pattern having a step size of 100, 200, 300, and 400 μm is formed, respectively, and the sliding angle after 3 months after the heat treatment are shown.

As described above, it can be seen that the substrate coated with silicone oil and subjected to heat treatment for 10 minutes has a predetermined superhydrophobicity, although the contact angle decreases by a predetermined amount and the sliding angle increases by a predetermined amount over time. .

Here, for durability measurement, the damaged superhydrophobic surface is subjected to the above process for forming a superhydrophobic surface, that is, coating the substrate surface with silicone oil (ST150) and heat-treating the silicon oil-coated substrate (ST160) again It can be repaired by performing

In the above description of the present invention, it is assumed that the substrate is made of stainless steel.

Even when the substrate is made of a different material, it may have superhydrophobicity as follows.

8 is a table showing the contact angle and the sliding angle according to the material of the substrate.

8A to 8G show contact angles and sliding angles of substrates made of aluminum, copper, titanium, ceramic-glass, sapphire, and titanium dioxide.

After preparing four substrates as a sample according to the material, laser is irradiated to each substrate at a laser scan speed of 10 mm / s, and a pattern with a step size of 200 μm is formed, followed by silicone oil coating and predetermined heat treatment (200 ° C, 10 minutes) ), the contact angle and sliding angle of the formed superhydrophobic surface.

Referring to FIG. 8 , it can be seen that a superhydrophobic surface can be formed by performing pattern formation, silicone oil coating, and heat treatment on substrates of various materials.

The present invention is superhydrophobic compared to the conventional technique of forming a superhydrophobic surface using only heat treatment by performing silicone oil coating and heat treatment on a substrate having a pattern formed on the surface by laser irradiation to form a superhydrophobic surface. This allows the time and energy required for surface formation to be reduced. In addition, the present invention allows the superhydrophobic surface to return to its original state by applying a silicone oil coating and heat treatment for forming the superhydrophobic surface when the superhydrophobic surface is damaged.

Although the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

1: transparent substrate 10: laser generator

Claims (8)

preparing a substrate;
preparing the laser;
forming a pattern on a surface of the substrate by irradiating the laser onto the substrate;
coating the substrate with the pattern on its surface with silicone oil; and
Superhydrophobic surface manufacturing method comprising the step of heat-treating the silicon oil-coated substrate at a temperature of 50 to 250 ℃ lower than the ignition temperature of the silicone oil. According to claim 1,
The substrate is
A method of making superhydrophobic surfaces comprising aluminum, copper, titanium, stainless steel, ceramic-glass, sapphire and titanium dioxide. According to claim 1,
The step size of the pattern is 100 to 400 μm,
The scan speed of the laser is 5 to 10 mm / s of superhydrophobic surface production method. According to claim 1,
The step size of the pattern is 100 to 200 μm,
The scan speed of the laser is 50 mm / s or less of the superhydrophobic surface production method. According to claim 1,
The step size of the pattern is 100 μm or less,
The scan speed of the laser is 100mm / s or less of the superhydrophobic surface production method. According to claim 1,
The concentration of the silicone oil to be coated on the substrate is 0.1 to 100% by volume of the superhydrophobic surface manufacturing method. According to claim 1,
The heat treatment is
A superhydrophobic surface preparation method performed for 5 to 10 minutes. In the repair method of a superhydrophobic substrate having a superhydrophobic surface prepared by the superhydrophobic surface preparation method of any one of claims 1 to 7,
coating the silicone oil on the surface of the damaged portion of the superhydrophobic surface;
A method of repairing a superhydrophobic substrate by performing a heat treatment on the superhydrophobic surface coated with the silicone oil at a temperature lower than the ignition temperature of the silicone oil to repair the superhydrophobic surface.

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