Atmospheric pressure plasma reactor for surface modification, plasma device and surface modification method using the same

Abstract

The present invention provides an atmospheric pressure plasma reactor for surface modification, a plasma device using the same, and a surface modification method using the same. Specifically, the atmospheric pressure plasma reactor for surface modification according to the present invention can efficiently spray plasma or active gas and / or active material ionized by plasma onto a workpiece even under atmospheric pressure conditions and can process it uniformly, thereby enabling economical and effective surface modification of the workpiece.

Description

Technology Field

[0001] The present invention relates to an atmospheric pressure plasma reactor for surface modification, a plasma device using the same, and a surface modification method. Background Technology

[0002] Recently, with the increasing demand for high-performance materials and components across various industrial sectors, surface modification technologies aimed at improving the physical and chemical properties of workpiece surfaces are becoming crucial for controlling product performance based on surface characteristics. In particular, plasma-based surface treatment methods are attracting attention for being environmentally friendly, highly energy-efficient, and applicable to a wide range of materials compared to conventional chemical or mechanical processing methods.

[0003] Generally, plasma reactors ionize gases under specific conditions to generate various active species, and utilize these active species to alter the surface properties of the workpiece. For example, Metal-Organic Frameworks (MOFs) can improve performance by generating defects within the framework through plasma.

[0004] As a plasma device for enhancing the performance of metal-organic frameworks (MOFs), vacuum plasma devices have the advantage of a longer Debye length compared to atmospheric pressure plasma devices, which allows plasma-ionized gas to be effectively injected into the MOFs. However, compared to atmospheric pressure plasma reactors, vacuum plasma reactors have disadvantages, such as the need for expensive vacuum equipment and leak management; unsuitability for continuous mass production and high-speed processing due to high-pressure environments and complex device configurations; and difficulty in securing consistent results in the event of vacuum system failure due to complex setup, maintenance, and operation methods.

[0005] Therefore, in the field of surface treatment technology, there is a demand for economical and effective surface modification methods that complement the limitations of existing plasma surface treatment technology. In other words, new surface treatment technologies are required in the fields of material processing and functionality enhancement.

[0006] As background technology for this invention, Korean Patent Publication No. 10-2020-0046835 discloses CO using a dielectric barrier discharge plasma method. x A method for producing light hydrocarbons through a hydrogenation reaction is described. The problem to be solved

[0007] The objective of the present invention is to provide an atmospheric pressure plasma reactor for surface modification that stably generates plasma even under atmospheric pressure, efficiently sprays the generated plasma or active gas or active material ionized by the plasma onto a workpiece for uniform processing, thereby maximizing surface modification efficiency and improving process repeatability and process reliability.

[0008] Another objective of the present invention is to provide an economical and effective plasma device that enables high-speed processing or mass production without expensive vacuum equipment or complex device configurations.

[0009] Another objective of the present invention is to provide a surface modification method that effectively generates defects within Metal-Organic Frameworks (MOFs) to improve the processing and functionality of the Metal-Organic Frameworks.

[0010] The problems of the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0011] An atmospheric pressure plasma reactor for surface modification according to one aspect of the present invention comprises a tubular housing, a first electrode provided at the bottom of the housing, wherein the first electrode comprises at least one surface modification portion having at least one lower portion in contact with a workpiece, at least one second electrode spaced apart from the first electrode, and a dielectric disposed between the first electrode and the second electrode.

[0012] In one embodiment of the present invention, the first electrode can be detachably attached to the housing.

[0013] In one embodiment of the present invention, the first electrode and / or the second electrode may be selected from a pin type, needle type, wire type, rod type, plate type, and a combination thereof.

[0014] In one embodiment of the present invention, the degree of exposure of the first electrode from the workpiece can be controlled so that the degree of contact between the first electrode and the workpiece varies.

[0015] In one embodiment of the present invention, the workpiece may be in a powder state.

[0016] In one embodiment of the present invention, the workpiece may be a metal-organic framework (MOF) powder.

[0017] In one embodiment of the present invention, the plasma reactor may be used to improve the performance of the workpiece.

[0018] In one embodiment of the present invention, the performance improvement may be to improve at least one of hydrophilic and / or hydrophobic properties, sensitivity and selectivity to gas, and adsorption capacity for moisture or gas.

[0019] In one embodiment of the present invention, the size of the dielectric may be greater than or equal to the size of the second electrode.

[0020] In one embodiment of the present invention, the dielectric may be disposed in contact with the second electrode.

[0021] In one embodiment of the present invention, the voltage applied between the first electrode and the second electrode may be an alternating current (AC) voltage of 1 kV or more and 70 kV or less, or a pulse voltage.

[0022] In one embodiment of the present invention, the plasma reactor may further include a shaker for stirring the workpiece.

[0024] A plasma device for improving powder performance according to another aspect of the present invention includes a plasma reactor according to the present invention to improve the performance of a powder to be processed.

[0025] In one embodiment of the present invention, the performance of the powder to be treated is improved by an active gas and / or active material generated by the plasma when at least the upper part of the first electrode is not in contact with the powder to be treated, and when at least the upper part of the first electrode is in contact with the powder to be treated, the performance of the powder to be treated can be improved by the generated plasma.

[0026] In one embodiment of the present invention, the powder to be treated may be a metal-organic framework (MOF) powder.

[0027] In one embodiment of the present invention, the performance improvement may be to improve at least one of hydrophilic and / or hydrophobic properties, sensitivity and selectivity to gas, and adsorption capacity for moisture or gas.

[0028] A surface modification method according to another aspect of the present invention improves the performance of a workpiece by using a plasma reactor according to the present invention. Effects of the invention

[0029] An atmospheric pressure plasma reactor for surface modification according to one embodiment can stably generate plasma even under atmospheric pressure conditions.

[0030] In one embodiment, an atmospheric pressure plasma reactor for surface modification can efficiently spray plasma or an active gas or active material ionized by plasma onto a workpiece and process it uniformly, thereby improving the efficiency of performance improvement and process reliability of the workpiece.

[0031] A plasma device of one embodiment enables high-speed processing or mass production without expensive vacuum equipment or complex device configuration, and can generate plasma economically and effectively.

[0032] A surface modification method of one embodiment can effectively generate defects within metal-organic frameworks (MOFs) to improve the processing and functionality of the metal-organic frameworks.

[0033] However, the effects of the present invention are not limited to the above effects, and may be extended in various ways without departing from the spirit and scope of the present invention. Brief explanation of the drawing

[0034] FIG. 1 is a schematic diagram of an atmospheric pressure plasma reactor for surface modification according to one embodiment of the present invention. FIG. 2 is a photograph showing a workpiece modified by an atmospheric pressure plasma generator for surface modification according to one embodiment of the present invention. Figure 3 is a photograph showing a workpiece damaged during the surface modification process as a comparative example according to the present invention. Figure 4 is a photograph of plasma generation in an atmospheric pressure plasma reactor for surface modification according to one embodiment of the present invention. FIG. 5a is a graph of the gas adsorption isotherms of Examples 1 to 10 according to the present invention. FIG. 5b is a graph of an adsorption isotherm showing the adsorption characteristics of methane (CH4) in Examples 1 to 10 according to the present invention. FIG. 5c is a graph of an adsorption isotherm showing the adsorption characteristics of carbon dioxide (CO2) in Examples 1 to 10 according to the present invention. FIG. 6a is a scanning electron microscope (SEM) image of Example 1 surface-modified according to the present invention. FIG. 6b is a scanning electron microscope (SEM) image of Example 6 surface-modified according to the present invention. FIG. 6c is a scanning electron microscope (SEM) image of Example 7 surface-modified according to the present invention. FIG. 6d is a scanning electron microscope (SEM) image of Example 8 surface-modified according to the present invention. FIG. 6e is a scanning electron microscope (SEM) image of Example 9 surface-modified according to the present invention. FIG. 6f is a scanning electron microscope (SEM) image of Example 10 surface-modified according to the present invention. FIG. 7 is an X-ray diffraction (XRD) graph of Example 1 and Examples 6 to 10 surface-modified according to the present invention. FIG. 8 is a theoretical molecular model image showing the defect locations of a Metal-Organic Framework (MOF) powder for performance improvement according to one embodiment of the present invention. FIG. 9 is a Fourier Transform Infrared Spectroscopy (FT-IR) graph of Example 1 and Examples 6 to 10 surface-modified according to the present invention. FIG. 10 is an X-ray Photoelectron Spectroscopy (XPS) graph of Example 1 and Examples 6 to 10 surface-modified according to the present invention. FIG. 11 is a correlation graph of XPS binding ratio-gas adsorption amount for Example 1 and Examples 6 to 10 surface-modified according to the present invention. Specific details for implementing the invention

[0035] The present invention is susceptible to various modifications and may take various forms, and the purposes, other purposes, features, and advantages of the invention will be readily understood through the accompanying drawings and the preferred embodiments below. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to ensure that the spirit of the invention is sufficiently conveyed to a person skilled in the art.

[0036] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains, and in the event of a conflict, the description in this specification, including the definitions, shall prevail.

[0037] In this specification, terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the invention, the first component may be named the second component, and similarly, the second component may be named the first component. A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0038] In this specification, where a component (or region, layer, part, etc.) is described as being "on," "connected," or "combined" with another component, it means that it may be directly placed / connected / combined with the other component, or that a third component may be placed between them.

[0039] In this specification, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0040] In this specification, the statement that any configuration is disposed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is disposed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration disposed on (or below) said component.

[0041] "And / or" includes all one or more combinations that the associated configurations can define.

[0042] The size and thickness of each component shown in the drawings are arbitrarily depicted for the convenience of explanation and are not limited thereto.

[0044] The present disclosure is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present disclosure. In describing the present disclosure, if it is determined that a detailed description of related prior art may obscure the essence of the present disclosure, such detailed description is omitted.

[0046] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In describing with reference to the accompanying drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0048] An atmospheric pressure plasma reactor for surface modification according to one aspect of the present invention comprises a tubular housing, a first electrode provided at the bottom of the housing, wherein the first electrode comprises at least one surface modification portion having at least one lower portion in contact with a workpiece, at least one second electrode spaced apart from the first electrode, and a dielectric disposed between the first electrode and the second electrode.

[0049] FIG. 1 shows a schematic diagram of an atmospheric pressure plasma reactor (1) for surface modification according to one embodiment of the present invention. Although not limited thereto, referring to FIG. 1, the atmospheric pressure plasma reactor (1) for surface modification according to the present invention comprises a tubular housing (100) and a plate-shaped first electrode (200) provided at the bottom of the housing (100), and the first electrode may be provided with a plurality of surface modification parts (220) in contact with a workpiece (300). A dielectric (500) may be provided on the upper part of the housing (100), and a second electrode (400) in contact with the dielectric (500) may be disposed on the dielectric (500).

[0050] Additionally, a process gas inlet (120) and a process gas outlet (140) may be provided on one side of the housing (100). The process gas may be injected in direction A and discharged in direction B. The process gas may be selected from Ar, O2, N2, Air, and combinations thereof, although not limited thereto.

[0051] In one embodiment of the present invention, the first electrode (200) may be fixedly attached to the lower part of the housing (100) or provided to be detachably attached to the housing (100). For example, if the first electrode (200) is fixedly attached to the lower part of the housing (100), the workpiece may be introduced or discharged through the upper part or side of the housing (100). On the other hand, if the first electrode (200) is detachably attached to the lower part of the housing (100), the lower part of the housing (100) is open, so that the first electrode (200) loaded with the workpiece (300) can be connected to the lower part of the open housing (100). At this time, the upper part of the housing (100) may be configured to be sealed by a dielectric (500) and a second electrode (400). FIG. 2 shows a photograph of a workpiece modified by an atmospheric pressure plasma generator for surface modification according to one embodiment of the present invention. Referring to FIG. 2, it can be seen that the powder, which is the workpiece surface modified by the present invention, has been surface modified without damage.

[0052] The above housing (100) is not particularly limited as long as it has a structure in which the first electrode (200) can be fixedly attached or detachably attached. As an example, a cylindrical housing (100) is shown in FIG. 2, but a through-type shape is not limited thereto.

[0053] Additionally, the housing (100) is not particularly limited as long as it is made of a material capable of applying a high voltage between the first electrode (200) and the second electrode (400). The housing (100) may be formed of an inorganic insulating material (e.g., ceramic, glass) or an organic insulating material (e.g., plastic, PTFE, etc. polymer), but is not limited thereto.

[0054] The first electrode and the second electrode can generate plasma by a constant potential difference (voltage difference). When a voltage is applied to at least one of the first electrode or the second electrode, a potential difference is formed between the electrodes, and a plasma discharge can be induced. One of the electrodes may be referred to as the first electrode, and the electrode forming a specific potential difference with the first electrode may be referred to as the second electrode. The second electrode forming a specific potential difference with the first electrode may be a grounded electrode or an ungrounded electrode. For example, both the first electrode and the second electrode may be voltage-applied electrodes, or the first electrode may be a voltage-applied electrode and the second electrode may be a grounded electrode. That is, both the first electrode and the second electrode may be connected to a power source, or each may be connected to a power source and connected to a ground, respectively. There may be no special limitations on the first electrode and the second electrode as long as the potential difference (voltage difference) between the first electrode and the second electrode is maintained. The above potential difference (voltage difference) may be 1 kV to 70 kV, 1 kV to 60 kV, or 5 kV to 50 kV, but is not limited thereto.

[0055] For example, referring to FIG. 1, the first electrode (200) may be a high-voltage electrode that generates plasma, and the second electrode (400) may be a ground electrode, and the present invention will be described below based on this.

[0057] The first electrode (200) and / or the second electrode (400) may consist of two or more multiple electrodes. The atmospheric pressure plasma reactor (1) for surface modification according to the present invention may have structural flexibility by adjusting the shape, size, number, etc. of the first electrode (200) and / or the second electrode (400). As a result, it can be applied to various types of devices, allowing for customization according to the process and / or device. For example, if there are multiple surface modification parts (220) of the first electrode (200), the discharge area is expanded and the contact area with the workpiece can be maximized, thereby greatly improving the processing performance and uniformity of the workpiece. In addition, the reaction efficiency of the plasma can be increased by placing the surface modification parts (220) of the first electrode (200) at various points.

[0058] Meanwhile, if the effective area of ​​the second electrode (400) is insufficient, plasma may leak to unexpected paths or external devices, or unnecessary discharge may occur. Therefore, it is important for the second electrode (400) to secure a sufficient effective area. Accordingly, the plasma reactor (1) of the present invention can secure a sufficient effective area by adjusting the number and / or area of ​​the second electrode (400). In this way, the plasma reactor (1) of the present invention is equipped with an appropriate area of ​​the second electrode (400) to lower the resistance of the entire discharge path and help to equalize the electric field, thereby reducing the risk of local over-discharge. In addition, even in large plasma systems, the current path at each point is shortened, thereby minimizing voltage drop and non-uniform discharge problems.

[0059] The plasma reactor (1) according to the present invention can maximize discharge control and the efficiency and stability of the plasma reactor (1) by means of a dielectric (500) disposed between the first electrode (200) and the second electrode (400). By means of the dielectric (500), when voltage is applied, the plasma is generated finely and uniformly, thereby ensuring uniformity of the discharge, and the dielectric (500) controls the flow of current, thereby preventing energy loss or overheating.

[0060] In one embodiment of the present invention, the first electrode (200) and / or the second electrode (400) may be selected from structures such as a pin, needle, wire, rod, plate, and combinations thereof. Although not limited thereto, the first electrode (200) may, for example, be a combination of a pin or needle on a plate shape, and the pin or needle may be referred to as a surface modification part (220). Although not limited thereto, it may be suitable for the surface modification part (220) to be a pin or needle shape so as to efficiently process the workpiece. Additionally, the second electrode (400) may be advantageous in terms of securing process uniformity of plasma density and energy distribution, but is not limited thereto.

[0061] The material of the first electrode (200) is not particularly limited as long as it is capable of forming plasma. For example, the first electrode (200) may be manufactured by selecting one or more materials from stainless steel, tungsten (W), brass, copper (Cu), copper alloy, aluminum, aluminum alloy, titanium (Ti), and other high corrosion-resistant alloys.

[0062] The above-mentioned second electrode (400, ground) may be manufactured by selecting one or more of stainless steel, copper alloy, aluminum alloy, corrosion-resistant alloys such as zinc, magnesium, and tantalum, and carbon (graphite), but is not limited thereto.

[0063] In one embodiment of the present invention, the first electrode (200) can control the degree of exposure of the surface modification portion (220) of the first electrode (200) to the workpiece (300) so that the degree of contact with the workpiece (300) varies. Depending on the area of ​​contact between the workpiece (300) and the first electrode (200), the surface modification (e.g., performance improvement) mechanism of the workpiece may vary. Specifically, the surface of the workpiece (300) may be modified directly by plasma generated by the first electrode (200), or the surface of the workpiece may be modified by active gases and / or active substances activated by plasma. However, in a modification process where the workpiece (300) is directly modified by plasma, high-energy particles come into contact with the workpiece, so setting conditions that consider the thermal and mechanical stability of the workpiece (e.g., plasma treatment conditions, material characteristics, plasma generation power, and chamber matching conditions) may be important factors. Figure 3 is a photograph showing a workpiece damaged during the surface modification process as a comparative example according to the present invention.

[0065] To improve the performance of the above-mentioned workpiece, an atmospheric pressure plasma for surface modification may be used. Specifically, it may be selected from dielectric barrier discharge, corona discharge, and glow discharge plasma, and dielectric barrier discharge may be the most suitable, but is not limited thereto.

[0067] In one embodiment of the present invention, the workpiece may be in a powder state. The atmospheric pressure plasma reactor for surface modification according to the present invention may be used as a workpiece, but is not limited thereto, polymer materials such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI), Teflon (PTFE), and polycarbonate (PC); metal materials such as aluminum (Al), copper (Cu), stainless steel (SUS), and zinc (Zn); ceramic / glass materials such as silica (SiO2), alumina (Al2O3), tempered glass, and substrates; fiber / fabric materials such as cotton, polyester, nylon, and rayon; adhesive materials such as industrial paper, synthetic paper, label paper, and film adhesive paper; electronic and optical materials such as FPCB, display films, wafers, and OLED structures; and bioengineering materials such as biocompatible polymers, hydrogels, and metal materials.

[0068] When the above-mentioned workpiece is a powder, the reaction surface area with plasma and / or active gases and / or active substances generated from the plasma is expanded and the reaction time is shortened, enabling uniform surface treatment on the surface of the powder particles, thereby improving the efficiency of performance enhancement. Furthermore, the powder with improved performance exhibits increased dispersion stability, and the contact time and degree of reaction with plasma, active gases, and / or active substances can be easily controlled, making process-specific surface modification possible in various industries.

[0069] Although not limited thereto, in one embodiment of the present invention, the workpiece may be a metal-organic framework (MOF) powder. Metal-organic frameworks are utilized in various fields such as energy, environment, medicine, catalysts, and sensors due to their advantages of high surface area, controllable pore structure, and the ability to combine various metals and ligands. However, performance improvement may be essential for metal-organic framework powders to achieve maximum efficiency in actual applications.

[0070] However, performance modification of Metal-Organic Frameworks (MOFs) can be difficult due to inherent structural limitations of the material and characteristics of the powder form. For example, in the powder state, Metal-Organic Frameworks may exhibit low inter-particle conductivity or thermal continuity and lack mechanical stability. Furthermore, many Metal-Organic Frameworks are unstable under moisture, acid / base, and / or high-temperature conditions, making it difficult to maintain performance in applications requiring high-temperature processes due to decomposition or structural collapse. On the other hand, the surface of Metal-Organic Framework powder can be efficiently modified using the atmospheric pressure plasma generator for surface modification according to the present invention.

[0071] FIG. 4 shows a photograph of plasma generation in an atmospheric pressure plasma reactor for surface modification according to one embodiment of the present invention. Referring to FIG. 4, it can be seen that in the atmospheric pressure plasma generator according to the present invention, plasma is generated uniformly and surface modification is performed.

[0072] In one embodiment of the present invention, the atmospheric pressure plasma reactor for surface modification can improve the performance of metal-organic framework powder through surface modification. Specifically, a method for improving the performance of a metal-organic framework includes intentionally deleting linkers or nodes present within the crystal of the metal-organic framework to create defects, thereby increasing active sites through the created defects to improve catalytic activity and / or adsorption performance. Additionally, there is a method of imparting new functions to the metal-organic framework by introducing additional functional groups or replacing functional groups (Post-Synthetic Modification, PSM).

[0073] Surface modification of a metal-organic framework according to the present invention increases active sites, improves pore accessibility, simultaneously improves catalytic and adsorption performance, and maintains the structural stability of the metal-organic framework; the performance improvement may be due to the aforementioned defects, but is not limited thereto.

[0074] The types of defects mentioned above include missing linker defects, missing node defects, substitutional defects, functional group defects, topological defects, and vacancy defects. Although not limited to these, functional group defects may be more suitable for surface modification of metal-organic frameworks according to the present invention. For example, carboxyl group (COOH) defects are a type of defect that plays an important role in improving the properties of metal-organic frameworks and can be efficiently controlled and introduced through a plasma process using an atmospheric pressure plasma reactor for surface modification according to the present invention. Specifically, if some of the organic ligands of the metal-organic framework are missing or partially modified, carboxyl group defects with increased reactivity are generated on the surface or within the framework. This alters the chemical properties of the surface, allowing it to interact with open metal sites at the metal nodes.

[0075] The atmospheric pressure plasma reactor for surface modification according to the present invention can control the degree of surface modification (e.g., defect density) according to the plasma treatment time, treatment intensity, type of process gas, and / or exposure time of the process gas. Although not limited thereto, the atmospheric pressure plasma reactor for surface modification according to the present invention can improve the performance of a workpiece by controlling at least one of the hydrophilic and / or hydrophobic characteristics of the workpiece surface, sensitivity and selectivity to gas, and adsorption capacity for moisture or gas. For example, in the case of surface modification of a metal-organic framework using the atmospheric pressure plasma reactor for surface modification according to the present invention, chemical interaction between active sites and target substances (e.g., harmful gases, reactants, adsorbed gas molecules, etc.) can be strengthened to improve chemical bonding strength, and physical adsorption can be increased by controlling surface roughness, surface energy, charge distribution, etc. through plasma treatment. In addition, by using the atmospheric pressure plasma reactor for surface modification according to the present invention, energy or electron transfer of the workpiece can be promoted, adhesion to the surface of other materials can be improved, and various properties such as antifouling / waterproofing, deodorizing properties, antistatic properties, improved dyeability or printability, and sterilization can be imparted.

[0077] In one embodiment of the present invention, the size of the dielectric may be greater than or equal to the size of the second electrode. The dielectric according to the above configuration can effectively inhibit surface discharge and improve capacitance, thereby mitigating sudden changes in voltage. Furthermore, the dielectric of the present invention protects against high-frequency signals or external interference and can generate finer and more uniform plasma, which can significantly improve the overall safety of the plasma reactor, such as improving plasma quality, controlling discharge, and enhancing energy efficiency.

[0078] Although not limited to this, if the dielectric is positioned more widely than the second electrode, it can mitigate the electric field concentration phenomenon that may occur at the edges of the electrode, thereby preventing unnecessary discharge or localized overheating. In addition, it can suppress the diffusion of plasma to the outside of the electrode, thereby reducing equipment damage or contamination caused by plasma. Ultimately, this results in a more uniform electric field distribution and stabilizes the density and energy distribution of the plasma, which has the advantage of increasing the uniformity of the process.

[0080] In one embodiment of the present invention, the dielectric material may be positioned in contact with the second electrode. Although not limited thereto, when the dielectric material is positioned in contact with the second electrode, the dielectric material limits the discharge current, thereby enabling the formation of a uniform and stable plasma. Furthermore, since the electrodes do not come into direct contact, corrosion or thermal damage to the second electrode can be prevented. This can extend the lifespan of the plasma device and reduce the frequency of maintenance.

[0081] Although not limited thereto, in one embodiment of the present invention, the applied voltage applied between the first electrode and the second electrode may be an alternating current (AC) voltage of 1 kV or more and 70 kV or a pulse voltage. Although not limited thereto, the applied voltage may be set to various values ​​ranging from several kV to tens of kV depending on the distance between the first electrode and the second electrode, process conditions, etc. For example, when applying voltage to the first electrode, the applied voltage may be 1 kV or more and 70 kV or less, 1 kV or more and 60 kV or less, and 5 kV or more and 50 kV or less, but is not limited thereto.

[0082] Although not limited to this, at voltages within the above range, it is easy to initiate a discharge with high voltage and form a stable non-thermal plasma. In particular, the generation of reactive species such as radicals and ions can be controlled, and overheating can be prevented through short cycles or short pulses. Furthermore, it can be adapted to various pressure and flow rate conditions, resulting in high energy efficiency, minimal thermal damage, and an improved lifespan.

[0083] In one embodiment of the present invention, the plasma reactor may further include a shaker capable of stirring the workpiece. The shaker can maximize the uniform mixing of the workpiece and reaction efficiency. For example, by continuously dispersing and mixing the workpiece so that the surface of the workpiece is continuously exposed to plasma and / or an active gas activated by the plasma, the surface modification effect can be maximized within the same time.

[0084] The shaker may vary depending on the characteristics of the workpiece, processing capacity, process conditions, and / or the durability of the plasma reactor. The shaker may utilize a vibratory shaker, rotary shaker, horizontal vibratory shaker, and combined shaker by means of vibration, rotation, ultrasonics, shock, and combinations thereof, but is not limited thereto.

[0085] In FIG. 1, the shaker (600) is positioned at the bottom of the atmospheric pressure plasma reactor for surface modification, but it is not limited thereto. The shaker (600) may be positioned at the side or top of the atmospheric pressure plasma reactor for surface modification according to the present invention, and in a large plasma reactor, it may be included as a stirring shaft (impeller, paddle, etc.) inside.

[0087] A plasma device for improving powder performance according to another aspect of the present invention includes a plasma reactor according to the present invention. The plasma device may include, but is not limited to, a gas supply device, a process control system, a protection and cooling device, a safety device, etc., in addition to the plasma reactor, and may further include additional components to improve the performance and stability of the device as needed.

[0089] The plasma device of the present invention may have a performance improvement mechanism that varies depending on the contact area between the first electrode and the workpiece (e.g., powder) within the plasma reactor. Although not limited thereto, in one embodiment of the present invention, when at least the upper portion of the first electrode does not come into contact with the workpiece, the performance of the workpiece may be improved by an active gas and / or active material generated by the plasma, and when at least the upper portion of the first electrode comes into contact with the workpiece, the performance of the workpiece may be improved by reacting with the workpiece by the generated plasma.

[0090] When the workpiece does not react directly with the plasma but reacts indirectly with active gases and / or active materials generated by the plasma, excessive damage or deformation to the powder surface caused by heat or electron impact can be reduced. Furthermore, compared to direct contact methods, temperature and processing intensity can be controlled more precisely, enabling uniform processing and large-area application, as well as reliably improving performance even on sensitive materials.

[0091] On the other hand, when the workpiece reacts directly with plasma, the reaction proceeds immediately through direct and powerful performance improvement, which can shorten process time. Furthermore, high-intensity treatment allows for the effective formation of surface defects and the introduction of functional groups, which can be advantageous for industrial applications. Meanwhile, when the workpiece reacts directly with plasma as described above, plasma treatment conditions, such as plasma intensity and treatment time, are appropriately controlled to minimize the risk of powder damage caused by excessive plasma energy, thereby enabling the realization of the desired surface modification effect without powder damage.

[0092] In one embodiment of the present invention, the plasma device may be used to improve the performance of a metal-organic framework (MOF) powder.

[0093] In one embodiment of the present invention, the performance improvement may be to improve at least one of hydrophilic and / or hydrophobic properties, sensitivity and selectivity to gas, and adsorption capacity for moisture or gas, but is not limited thereto.

[0095] A surface modification method according to another aspect of the present invention can improve the performance of various workpieces by utilizing the plasma reactor according to the present invention. For example, when the workpiece is a metal-organic framework powder, customized surface modification optimized for the workpiece is possible by controlling plasma treatment conditions (treatment time, voltage intensity, composition of process gas, treatment time, etc.), and uniform and reproducible treatment can be achieved. This can contribute to the development and application of high-performance powder materials required in various industrial fields.

[0096] When the above-mentioned workpiece is a metal-organic framework, performance improvement may be achieved due to defects, although this is not limited thereto, and said defects may be defects in carboxyl groups. By the surface modification method according to the present invention, the performance-improved metal-organic framework has its surface characteristics effectively altered, and catalytic activity, adsorption performance, durability, and functionality may be improved, but this is not limited thereto.

[0098] The following describes embodiments and comparative examples of the present invention. A plasma reactor for surface modification according to one embodiment is described in detail. Furthermore, the following examples are provided to aid in understanding the present invention, and the scope of the present invention is not limited thereto.

[0100] The present invention will be explained in more detail below through examples.

[0102] Examples

[0103] 1. Manufacture of a Plasma Reactor for Surface Modification

[0104] An atmospheric pressure plasma reactor for surface modification of powder was manufactured by the following method.

[0105] A housing with excellent heat resistance (transparent glass tube, length 300 mm, height 100 mm) was prepared, and a first electrode and a second electrode were installed facing each other on the lower and upper sides of the housing. On the lower side of the housing, a plurality of pin-shaped electrodes were installed as the first electrode, and the housing was manufactured so that some or all of the pin-shaped electrodes could come into contact with the workpiece. In addition, the upper side of the housing was covered with a dielectric, and a second electrode was installed on the dielectric. A shaker for uniform mixing of the workpiece was mounted on the outer lower side of the housing.

[0106] Each electrode was connected to an external RF (high frequency) power supply to supply the high frequency voltage (e.g., 13.56 MHz) required for plasma generation.

[0107] At this time, the gap and arrangement between the first electrodes, and the electrode spacing and position of the first and second electrodes were adjusted to meet the purpose of surface modification (performance improvement).

[0108] The lower part of the above housing is designed so that a first electrode loaded with a workpiece can be detachably attached.

[0109] After attaching the first electrode to both lower ends of the above housing, a stainless steel and / or aluminum cap capable of being securely sealed even at atmospheric pressure was installed, thereby fabricating a plasma reactor capable of stable operation even under atmospheric pressure conditions.

[0110] A process gas inlet (e.g., fitting and valve) is installed on the side of the housing or on one of the caps to allow the supply of process gases suitable for treatment, such as argon or nitrogen, at atmospheric pressure.

[0112] 2. Improvement of powder performance using a plasma reactor

[0113] An appropriate amount of powder was introduced into the manufactured plasma reactor, and process gas was supplied. High-frequency voltage was applied using an RF power supply to generate atmospheric pressure plasma inside the housing.

[0114] At this time, the performance improvement effect can be enhanced by adjusting the height of the first electrode. Specifically, when at least the upper part of the first electrode does not come into contact with the powder to be processed, the plasma emitted from the first electrode activates the process gas to generate a reactive gas, and the performance of the workpiece can be improved by the generated reactive gas.

[0115] On the other hand, when at least the upper part of the first electrode comes into contact with the powder to be processed, the generated plasma reacts with the powder to be processed, and the performance of the powder to be processed can be improved.

[0116] The connection part and internal structure of the plasma reactor of the present invention are designed so that powder can be uniformly diffused within the reactor. In particular, to ensure that the plasma treatment is uniformly exposed to the powder, a shaker is operated as needed to maximize the plasma exposure to the powder.

[0117] The above powder used was MOF-801. MOF-801 is one of the porous materials of the Metal-Organic Frameworks (MOFs) series, and is a modified structure of a Metal-Organic Framework based on the basic framework of UiO-66, and is a Zr-based Metal-Organic Framework composed of zirconium (Zr) metal and fumaric acid organic ligands.

[0118] After introducing MOF-801 into the above plasma reactor, gas was injected and the vacuum level was appropriately adjusted, and then plasma was generated through an external high-frequency power supply to modify the powder.

[0119] In order to verify the degree of performance improvement of the above-mentioned modified powder, Examples 1 to 10 were prepared by varying the type of gas introduced, the amount of gas introduced, and the exposure time when modifying the MOF-801 powder, and the specific conditions are shown in Table 1 below.

[0120] Example 1. Surface modification of MOF-801 powder was carried out without injecting a specific gas or air into the plasma reactor described above.

[0121] Example 2. Surface modification was carried out by exposing MOF-801 powder to air for 5 minutes without injecting a specific gas into the plasma reactor described above.

[0122] Example 3. Surface modification was carried out by exposing MOF-801 powder to air for 10 minutes without injecting a specific gas into the plasma reactor described above.

[0123] Example 4. Surface modification was carried out by exposing MOF-801 powder to air for 20 minutes without injecting a specific gas into the plasma reactor described above.

[0124] Example 5. Surface modification was carried out while injecting 100% Ar gas into the plasma reactor described above.

[0125] Example 6. Surface modification was carried out while injecting a mixed gas of 67% Ar gas and 33% N2 gas into the plasma reactor described above.

[0126] Example 7. Surface modification was carried out by injecting a mixed gas comprising 67% Ar gas, 32% N2 gas, and 1% H2 gas into the plasma reactor described above.

[0127] Example 8. Surface modification was carried out by injecting a mixed gas comprising 67% Ar gas, 32% N2 gas, and 1% O2 gas into the plasma reactor described above.

[0128] Example 9. Surface modification was carried out in the plasma reactor described above under the conditions of Example 7, and then the surface modification was carried out by changing to the conditions of Example 8.

[0129] Example 10. Surface modification was carried out in the plasma reactor described above under the conditions of Example 8, and then the surface modification was carried out by changing to the conditions of Example 7.

[0130]

[0132] result

[0133] Experimental Example 1. Evaluation of Surface Modification Performance

[0134] To evaluate the surface modification performance of the surface-modified (performance-improved) powder, the surface area activity and the degree of adsorption of specific gases were verified.

[0135] FIGS. 5a to 5c show the adsorption isotherm graphs of Examples 1 to 10 according to the present invention. Specifically, FIG. 5a is the adsorption isotherm graph of Examples 1 to 10 according to the present invention, FIG. 5b is the adsorption isotherm graph showing the adsorption characteristics of methane (CH4) of Examples 1 to 10 according to the present invention, and FIG. 5c is the adsorption isotherm graph showing the adsorption characteristics of carbon dioxide (CO2) of Examples 1 to 10 according to the present invention.

[0136] Referring to Fig. 5a, it was confirmed that the volume of gas adsorbed by 1 g of sample under standard conditions with respect to relative pressure exhibited a constant waveform regardless of the treatment conditions for performance modification. Additionally, referring to Figs. 5b and 5c, Examples 1 to 10 are relative pressure ( P / Po It was confirmed that as ) increases, the adsorption amounts of CH4 and CO2 also increase. In addition, when examining the adsorption amounts of Example 10, it can be seen that the adsorption amount of CH4 is higher compared to other examples, while the adsorption amount of CO2 is lower compared to other examples. This suggests that the metal-organic framework powder can possess gas selectivity due to the performance improvement according to the present invention.

[0137] Table 2 shows the CH4 adsorption amounts and the relative increase / decrease rates of CH4 adsorption amounts for Examples 1 to 10. By referring to Table 2, it can be confirmed that the amount of CH₄ adsorption varies depending on the modification conditions, and through this, it is possible to determine under which modification conditions the CH₄ adsorption performance is effectively improved.

[0138]

[0140] Experimental Example 2. Evaluation of Skeletal Body Maintenance

[0141] In order to determine the degree of retention of the crystal or particle framework even after performance improvement, Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) graphs of Examples 1 and 6 to 10 were examined. Figures 6a to 6f show Scanning Electron Microscope (SEM) images of Examples 1 and 6 to 10 surface-modified according to the present invention. Referring to Figures 6a to 6f, it can be confirmed that the framework is retained in all of Examples 1 and 6 to 10.

[0142] In addition, FIG. 7 shows the X-ray diffraction (XRD) graphs of Example 1 and Examples 6 to 10 surface-modified according to the present invention. Referring to FIG. 7, it can be confirmed that Example 1 and Examples 6 to 10 all have the same or similar crystal structure.

[0144] Experimental Example 3. Evaluation of Structural Properties in Metal-Organic Frameworks

[0145] To evaluate the structural characteristics (-COOH linker defects) of the surface-modified MOF powders of Examples 1 and 6 to 10, Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS) analyses were performed and are shown in FIGS. 9 to 11. FIG. 8 shows a theoretical molecular model indicating the defect locations of the metal-organic framework powder for performance improvement according to one embodiment of the present invention. Referring to FIG. 8, the metal-organic framework powder can have its performance improved by plasma treatment, which causes the carboxyl group (COOH) at the top of the metal-organic framework structure to be bonded.

[0146] FIG. 9 shows Fourier Transform Infrared Spectroscopy (FT-IR) graphs of Examples 1 and 6 to 10 surface-modified according to one embodiment of the present invention. Referring to FIG. 9, Examples 1 and 6 to 10 all exhibited similar waveforms, and 1670 cm -1 A peak (carboxyl group peak) was identified. This suggests that the binding environment of the organic ligand within the metal-organic framework structure has changed, implying that a defect has been created. In particular, compared to Example 1, the decrease in the peak in Examples 6 to 10 indicates that the degree of defect creation in Examples 6 to 10 has increased compared to Example 1.

[0147] Referring to Fig. 10, the presence and content of binder species (Zr-O-Zr, Zr-(OH)-Zr, Zr-OC, etc.) generated by the performance improvement of the metal-organic framework powder can be confirmed by the area of ​​the graph.

[0148] In addition, referring to FIG. 11, the ratio of Zr-OC represents missing linkers resulting from plasma treatment. In Example 1, the degree of defects was high, but the degree of CH4 adsorption was low. On the other hand, in Example 10, the degree of defects was low, but the degree of CH4 adsorption was very high. Through this, it can be confirmed that using the plasma reactor according to the present invention generates defects within the metal-organic framework structure, and the performance of the metal-organic framework is improved by said generated defects.

[0150] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art or those with ordinary knowledge in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and technical scope of the invention as described in the claims set forth below.

[0151] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims. Explanation of the symbols

[0153] 1: Plasma reactor 100: Housing 120: Process gas inlet 140: Process gas outlet 200: First electrode 220: Surface modification part of the first electrode 300: Workpiece 400: Second electrode 500: Genome 600: Shaker A: Process gas injection direction B: Process gas discharge direction

Claims

Claim 1 An atmospheric pressure plasma reactor for surface modification, comprising: a tubular housing; a first electrode provided at the bottom of the housing, wherein the first electrode comprises at least one surface modification portion having at least one lower portion in contact with a workpiece; at least one second electrode disposed spaced apart from the first electrode; and a dielectric disposed between the first electrode and the second electrode; wherein the workpiece is in a powder state. Claim 2 In claim 1, the first electrode is an atmospheric pressure plasma reactor for surface modification that is detachably attached to the housing. Claim 3 An atmospheric pressure plasma reactor for surface modification according to claim 1, wherein the first electrode and / or second electrode is selected from structures of pin, needle, wire, rod, plate, and combinations thereof. Claim 4 In claim 1, the atmospheric pressure plasma reactor for surface modification, wherein the degree of exposure of the first electrode from the workpiece can be adjusted so that the degree of contact with the workpiece varies. Claim 5 delete Claim 6 An atmospheric pressure plasma reactor for surface modification, wherein the workpiece in claim 1 is a metal-organic framework (MOF) powder. Claim 7 In claim 1, the plasma reactor is an atmospheric pressure plasma reactor for surface modification, for improving the performance of the workpiece. Claim 8 An atmospheric pressure plasma reactor for surface modification according to claim 7, wherein the performance improvement is to improve at least one of hydrophilic and / or hydrophobic properties, sensitivity and selectivity to gases, and adsorption capacity for moisture or gases. Claim 9 An atmospheric pressure plasma reactor for surface modification according to claim 1, wherein the size of the dielectric is greater than or equal to the size of the second electrode. Claim 10 In claim 1, the dielectric is an atmospheric pressure plasma reactor for surface modification, which is positioned in contact with a second electrode. Claim 11 An atmospheric pressure plasma reactor for surface modification according to claim 1, wherein the voltage applied between the first electrode and the second electrode is an alternating current (AC) voltage of 1 kV or more and 70 kV or less. Claim 12 An atmospheric pressure plasma reactor for surface modification according to claim 1, wherein the plasma reactor further comprises a shaker for stirring the workpiece. Claim 13 A plasma device for improving powder performance, comprising an atmospheric pressure plasma reactor for surface modification according to any one of claims 1 to 4 and 6 to 12, for improving the performance of a powder to be treated. Claim 14 In claim 13, the plasma device for improving powder performance is such that when at least the upper portion of the first electrode does not come into contact with the powder to be worked on, the performance of the powder to be worked on is improved by an active gas and / or active material generated by the plasma, and when at least the upper portion of the first electrode comes into contact with the powder to be worked on, the performance of the powder to be worked on is improved by the generated plasma. Claim 15 A plasma device for improving powder performance, wherein, in paragraph 13, the powder to be treated is a Metal-Organic Framework (MOF) powder. Claim 16 A plasma device for improving powder performance according to claim 13, wherein the performance improvement is to improve at least one of hydrophilic and / or hydrophobic properties, sensitivity and selectivity to gas, and adsorption capacity to moisture or gas. Claim 17 A surface modification method for improving the performance of a workpiece by using an atmospheric pressure plasma reactor for surface modification according to any one of claims 1 to 4 and 6 to 12.

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