KR102281404B1 - Coating method of super-hydrophobic surface - Google Patents

Abstract

The present invention relates to a superhydrophobic surface coating method, which can impart superhydrophobicity to the surface using plasma, and the manufacturing process is simple. In addition, the filter for air purification having a superhydrophobic surface can primarily remove foreign substances such as dust due to its superhydrophobic property, thereby improving the filter's performance and has a self-cleaning effect.

Description

Coating method of super-hydrophobic surface

The present invention relates to a method for coating a superhydrophobic surface of a filter for air purification.

Recently, a technology that can effectively control the wetting behavior of a liquid on a solid surface is attracting attention in terms of scientific and industrial applications. The wettability of the surface of the material is determined by the surface energy, or by controlling the microstructure of the surface to a micro- and nano-level complex structure, the wettability is extremely reduced, and a super water-repellent surface with a contact angle to water of 150° or more can be realized. Most of the superhydrophobic surfaces are based on the superhydrophobic surface structure that exists in nature. In general, natural materials with superhydrophobicity include lotus leaves, rice leaves, and wings of butterflies and cicadas. In fact, the lotus leaf exhibits superhydrophobicity with a water contact angle of 161°, and this property is due to the numerous micro- and nano-level microprotrusions formed on the surface of the lotus leaf. The microprotrusions on the surface of the lotus leaf minimize the contact area with water and are coated with a hydrophobic material to prevent water from entering between the protrusions. Foreign substances can be removed together. This is called the lotus effect or the lotus effect, and it can be applied to various fields such as window films, solar cell films, transparent electrode manufacturing inks, display functional films, building exterior materials, glasses, lenses, and cameras.

In order to realize a superhydrophobic surface, low surface energy and high surface roughness are required, and for this purpose, a method having nano- or micro-scale roughness using nano-sized organic/inorganic particles has been reported. This is largely divided into two methods. The first is a method of making a nanostructured surface and coating a material with low surface energy, and a micro-sized single-layer structure and a nano-sized structure within the single-layer structure are formed on the surface of the mold by chemical etching. After forming the groove structure, heat and pressure are applied to the etched mold to transfer the polymer structure, and the transferred polymer structure is removed from the mold. As nanomaterials, fluorine compounds, inorganic materials such as silica and carbon materials, metals, and polymer materials such as polypropylene and polystyrene are used. In general, fluorine-based compounds or polymers with low surface energy are widely used. However, this method has the advantage of realizing super water-repellent properties by conveniently treating various types of material surfaces with materials with low surface energy, but requires a post-treatment process for hydrophobization of the surface such as fluorination treatment, so the manufacturing process is relatively simple. It is complex, difficult to mass-produce, and has a low contact angle. The second method is to directly implement a nanostructured surface using a material with low surface energy. This has the advantage of being able to implement a super water-repellent nanostructured surface at once without any special treatment, but there is a problem that it completely depends on the properties of the material. In addition to this, various technologies for implementing superhydrophobicity are being developed, but they are still insufficient in technical and economic aspects.

On the other hand, among the methods of improving the surface properties of a material, a plasma surface treatment technique can be used to change the surface properties without affecting the basic properties. In this method, the property change is limited to the surface layer and occurs uniformly, so the treated surface It has a wide range of advantages in surface treatment because it can handle all materials that are stable at low temperatures and at the same time can handle all materials stably.

Accordingly, the present inventors completed the present invention by realizing a superhydrophobic surface through plasma polymerization as a result of conducting research to impart excellent superhydrophobicity through a simple manufacturing process.

Korean Patent Publication No. 10-2018-0031248

The present invention has been devised to solve the above problems, and an object of the present invention is to provide a superhydrophobic surface coating method having a simple manufacturing process, excellent coating power, and a high contact angle.

In addition, an object of the present invention is to provide an air purifying filter with an improved filter function by being coated by the above coating method and having a superhydrophobic surface, which can primarily remove foreign substances such as dust.

In order to solve the above problems, the present invention comprises the steps of: 1) mixing trimethylsilyl methacrylate and methyl methacrylate; 2) injecting the mixture together with a gas into a plasma reactor and spraying it on a substrate; And 3) plasma treatment by plasma polymerization coating; provides a superhydrophobic surface coating method comprising a.

After step 3), the surface of the substrate has superhydrophobicity, and in step 1), trimethylsilyl methacrylate and methyl methacrylate are mixed in a molar ratio of 4:1.

The plasma is a low-temperature plasma, the plasma treatment time is 3 to 6 minutes, and the power is 15 W.

The gas includes nitrogen gas, and the substrate is made of glass, metal, non-woven fabric, acrylic, spandex, polymer, ceramic, paper, plastic, silicone, wool, silk, cotton, flax, jute, wood, nylon or activated carbon fiber. include

In another aspect, the present invention provides a filter for air purification coated by the coating method, and the surface of the filter for air purification is characterized in that it is superhydrophobic.

According to the present invention, superhydrophobicity can be imparted to the surface by polymerization coating using plasma, the manufacturing process is simple, and the air purification filter having a superhydrophobic surface primarily removes foreign substances such as dust due to the superhydrophobic property It is possible to improve the performance of the filter and has a self-cleaning effect.

1 shows a contact angle measurement result of a coated glass substrate according to an embodiment of the present invention.
2 shows a Raman measurement result of a coated glass substrate according to an embodiment of the present invention.
3 shows an SEM image of a coated glass substrate according to an embodiment of the present invention.
4 shows an SEM image of a nonwoven filter according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail. In describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

The present invention comprises the steps of 1) mixing trimethylsilyl methacrylate and methyl methacrylate; 2) injecting the mixture together with a gas into a plasma reactor and spraying it on a substrate; And 3) plasma treatment by plasma polymerization coating; provides a superhydrophobic surface coating method comprising a.

After step 3), the surface of the substrate has superhydrophobicity.

In step 1), trimethylsilyl methacrylate and methyl methacrylate are preferably mixed in a molar ratio of 4:1, and when not mixed in the molar ratio, a superhydrophobic surface may not be formed or superhydrophobic performance may be reduced.

Preferably, the plasma is a low-temperature plasma. The plasma treatment time is preferably 3 to 6 minutes, more preferably 4 to 5 minutes, and most preferably 5 minutes. If the plasma treatment time is less than 3 minutes, plasma polymerization may not occur properly and coating may not be performed well. If the plasma treatment time is longer than 6 minutes, the substrate may be damaged.

The plasma power is preferably 15 W, and the gas is preferably nitrogen gas.

The substrate may include glass, metal, non-woven fabric, acrylic, spandex, polymer, ceramic, paper, plastic, silicone, wool, silk, cotton, flax, jute, wood, nylon or activated carbon fiber, but is not limited thereto no.

In another aspect, the present invention provides a filter for air purification coated by the coating method, and it is preferable that the surface of the filter for air purification is superhydrophobic.

Hereinafter, the present invention will be described in more detail by way of Examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1. Preparation of coating composition

The main monomer methyl methacrylate (hereinafter abbreviated as MMA) was mixed with trifluoromethyl methacrylate (hereinafter abbreviated as TFMA) and trimethylsilyl methacrylate (hereinafter abbreviated as TSMA) in the ratio shown in Table 1, respectively. In addition, dimethacrylate (hereinafter abbreviated as DMA) serving as a crosslinking agent was added at a ratio of 10% for comparative analysis.

Table 1 below shows the ratio of each component of Examples (1) to (24).

ingredient molar ratio DMA content to ingredients Example (1) TFMA: MMA 100:0 - Example (2) 80:20 - Example (3) 60:40 - Example (4) 40:60 - Example (5) 20:80 - Example (6) 0:100 - Example (7) 100:0 10% Example (8) 80:20 10% Example (9) 60:40 10% Example (10) 40:60 10% Example (11) 20:80 10% Example (12) 0:100 10% Example (13) TSMA: MMA 100:0 - Example (14) 80:20 - Example (15) 60:40 - Example (16) 40:60 - Example (17) 20:80 - Example (18) 100:0 10% Example (19) 80:20 10% Example (20) 60:40 10% Example (21) 40:60 10% Example (22) 20:80 10% Example (23) TFMA:TSMA:MMA 80:80:20 - Example (24) 80:80:20 10%

Example 2. Glass substrate coating

After putting 5 mL of the coating composition in the syringe, the syringe pump was connected to the low-temperature AC plasma device, and nitrogen gas was injected. Plasma polymerization coating was carried out for 10 minutes at 0.1 mL/sec on a glass substrate, and the voltage of the plasma device was fixed at 15 W/A.

Example 3. Superhydrophobicity evaluation

In order to evaluate the superhydrophobicity of Examples (1) to (24), the contact angle and transmittance of the glass substrate coated with the coating composition were measured and analyzed for comparison, and uncoated glass was used as a control.

Table 2 below shows the contact angle and transmittance measurement results.

Contact angle (°) Transmittance (%) UV (365 nm) IR (940 nm) VL (380~700nm) Example (1) 51.0 91.0 89.1 92.3 Example (2) 56.6 91.3 88.6 92.8 Example (3) 78.2 91.4 88.7 92.8 Example (4) 40.1 93.4 89.3 92.7 Example (5) 34.7 93.0 89.1 92.5 Example (6) 42.6 91.3 88.4 90.6 Example (7) 51.0 91.0 89.1 92.3 Example (8) 80.6 91.3 88.6 92.8 Example (9) 71.0 91.4 88.7 92.8 Example (10) 70.9 93.4 89.3 92.7 Example (11) 68.0 93.0 89.1 92.5 Example (12) 55.0 91.3 88.4 90.6 Example (13) 110 58.4 87.9 84.1 Example (14) 153 77.1 90.0 85.0 Example (15) 123 69.3 88.7 88.2 Example (16) 115 55.5 89.7 84.2 Example (17) 95.0 54.4 86.9 84.1 Example (18) 110 93.0 89.1 92.5 Example (19) 101 77.1 90.0 85.0 Example (20) 117 69.3 88.7 88.2 Example (21) 114 55.5 88.7 84.2 Example (22) 56.4 91.3 89.4 89.0 Example (23) 109 88.1 90.0 88.0 Example (24) 111 94.1 92.0 91.0 control 18.5 99.0 99.0 99.0

Referring to Table 2 and FIG. 1, it can be seen that Examples (13) to (17) in which TSMA and MMA are mixed exhibit a high contact angle of about 110° or more, thereby showing excellent hydrophobicity. Among them, Example 14, in which TSMA and MMA were mixed in a ratio of 80:20, exhibited a spherical, round shape with a contact angle of 153°, and showed the closest result to superhydrophobicity. On the other hand, when TFMA and MMA are mixed, it can be seen that the contact angle is as low as 80° or less.

When DMA was added to a mixture of TFMA and MMA, still showed a low contact angle, and when DMA was added to TSMA:MMA, Example (20) mixed in a 60:40 ratio showed a high contact angle close to superhydrophobicity at 117° indicated. In addition, Example 23 showed a contact angle of 109° and Example 24 had a contact angle of 111°, confirming that the mixing of the crosslinking agent DMA did not significantly affect the hydrophobic property.

On the other hand, it can be seen that the uncoated glass substrate has very low hydrophobicity at 18.5°.

Example 4. Coating Identification Evaluation

1) Raman analysis

Figure 2 shows the results of Raman analysis of the coated glass substrate, and it can be seen that the coating composition was coated on the glass substrate by confirming the ^{1000 cm -1 peak indicating the CH bond.}

2) Scanning electron microscope (SEM) analysis

SEM images of the front and side surfaces of the glass substrate coated with the coating composition were compared and analyzed through a scanning electron microscope (SEM). As shown in FIG. 3 , it was confirmed that plasma-polymerized precursors were coated on the surface of the glass substrate. Fig. 3(a) is the embodiment (3), Fig. 3(b) is the embodiment (8), Fig. 3(c) is the embodiment (20), Fig. 3(d) is the embodiment (14), and Fig. 3 (e) is an SEM image of Example 23, and FIG. 3(f) is an SEM image of Example 24.

When comparing TFMA and TSMA, it can be seen that when TSMA is mixed, more plasma-polymerized precursors are attached to the glass substrate, and the degree of adhesion according to the presence or absence of a crosslinking agent is similar.

On the other hand, when TFMA and TSMA were mixed, more precursors were formed than when TFMA was added alone, but the amount of precursors formed was decreased rather than when TSMA was added alone. When a crosslinking agent was added by mixing TFMA and TSMA, more precursors were formed than when no crosslinking agent was added. It is considered not to give

Example 5. Air purification filter manufacturing example and characteristic evaluation

A coating composition in which TSMA:MMA was mixed in an 80:20 ratio was plasma-polymerized and coated on the surface of the nonwoven fabric. In addition, 4% of the thermal initiator AIBN was added to the coating composition in which TSMA:MMA was mixed at 80:20, and then the nonwoven filter was immersed in the solution and dried, and then thermally polymerized at 70° C. for 3 minutes with a UV lamp. The coating degree was confirmed by measuring the coated nonwoven filter by SEM.

Figure 4 (a) is an SEM image of the non-coated non-woven filter, it can be confirmed that the non-woven fiber is not coated. FIG. 4(b) shows that the coating was performed using UV, and although the polymer was formed in the empty space between the nonwoven fibers, it can be seen that the nonwoven fiber strands were less coated. On the other hand, it was confirmed that the nonwoven filter coated by plasma polymerization was coated evenly and well on the fibers of the nonwoven filter, as shown in FIG. 4(c) .

Taken together, it can be seen that more precursors are coated on the surface with a high contact angle than on the surface with a low contact angle, and it can be seen that the coating power is excellent. Accordingly, it is expected that the performance of the filter will be improved by providing superhydrophobicity to the surface of the air purifying filter to primarily remove foreign substances such as dust.

Above, the present invention has been described by way of example, and various modifications will be possible without departing from the essential characteristics of the present invention by those of ordinary skill in the art to which the present invention pertains. Accordingly, the embodiments disclosed in the present specification are intended to illustrate, not to limit the present invention, and the spirit and scope of the present invention are not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technologies within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (10)

1) mixing trimethylsilyl methacrylate and methyl methacrylate;
2) injecting the mixture prepared in step 1) into a plasma reactor together with a gas and spraying it on a substrate; and
3) superhydrophobic surface coating method comprising a; plasma polymerization coating by plasma treatment in the reactor
The superhydrophobic surface coating method according to claim 1, wherein the surface of the substrate has superhydrophobicity after step 3)
The superhydrophobic surface coating method according to claim 1, wherein in step 1) trimethylsilyl methacrylate and methyl methacrylate are mixed in a molar ratio of 4:1
The superhydrophobic surface coating method according to claim 1, wherein the plasma treatment time in step 3) is 3 to 6 minutes.
The superhydrophobic surface coating method according to claim 1, wherein the plasma is a low-temperature plasma.
The superhydrophobic surface coating method according to claim 1, wherein the plasma treatment power is 15 W.
The superhydrophobic surface coating method according to claim 1, wherein the gas comprises nitrogen gas.
According to claim 1, wherein the substrate is any one from the group consisting of glass, metal, non-woven fabric, acrylic, spandex, paper, plastic, silicone, wool, silk, cotton, flax, jute, wood, nylon and activated carbon fiber Superhydrophobic surface coating method characterized by
A filter for air purification coated with the coating method according to any one of claims 1 to 8
The filter for air purification according to claim 9, wherein the surface of the filter is superhydrophobic.

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