Nano-nozzle having ink-philic coating layer for high-throughput and high-precision three-dimensional printing

Abstract

The present invention relates to a nano-nozzle capable of controlling the contact angle with ink to 45° or less by having the inner surface thereof coated with an ink-philic component, wherein the present invention, through modification of interfacial interactions between the ink and the coating layer formed on the inner surface, enables the ink to stably wet the inside of the nozzle and thus can improve the printing speed.

Description

Nano nozzle with an ink-friendly coating layer for high-flow and high-precision 3D printing

[0001] Cross-reference regarding related applications

[0002] The present application claims the benefit of priority to Korean Patent Application No. 2025-0184419 filed on December 12, 2024 and Korean Patent Application No. 2025-0119765 filed on August 27, 2025, the contents of which are incorporated by reference into this specification.

[0003] The present invention relates to a nano nozzle formed with an ink-friendly coating layer for high flow rate and high precision 3D printing.

[0004] Inkjet printing technology using nano nozzles is widely used in manufacturing processes for electronic devices, biochips, and high-resolution displays. However, because the inner diameter of nano-scale nozzles is very small, the viscosity of the ink, surface tension, and wettability between the nozzle wall and the ink have a direct impact on printing performance.

[0005] In particular, if the inner wall of the nozzle is not compatible with ink, the ink may not flow smoothly inside the nozzle or clogging may occur, resulting in reduced printing speed and decreased stability.

[0006] Existing technologies have primarily attempted to improve printing characteristics by changing the ink composition itself or adjusting the nozzle pressure conditions, but these approaches have problems such as significant limitations depending on the type of ink and low process efficiency. Therefore, there is a technical demand to enable stable and fast printing for various types of ink by improving the surface characteristics of the nozzle itself.

[0007] The present invention is a research supported by a national research and development project and has the following information.

[0008] [Assignment No.] 20264539

[0009] [Ministry Name] Ministry of SMEs and Startups

[0010] [Name of Project Management (Specialized) Agency] Korea Institute of Startup & Entrepreneurship Promotion

[0011] [Research Project Name] '24 Public-Private Joint Startup Discovery and Incubation Program Startups

[0012] [Project Title] World's First Polymer-based Homogeneous Porous Membrane Using 3D Nanoprinting Technology

[0013] [Name of Project Performing Organization] 3DMEM Co., Ltd.

[0014] [Research Period] 2024-11-01 ~ 2025-08-31

[0015]

[0016] [Assignment No.] 20264530

[0017] [Ministry Name] Ministry of SMEs and Startups

[0018] [Name of Project Management (Specialized) Agency] Korea Institute of Startup & Entrepreneurship Promotion

[0019] [Research Project Name] 2024 Public-Private Joint Startup Discovery and Incubation Program Startups

[0020] [Project Title] World's First Polymer-based Homogeneous Porous Membrane Using 3D Nanoprinting Technology

[0021] [Name of Project Performing Organization] 3DMEM Co., Ltd.

[0022] [Research Period] 2024-11-01 ~ 2025-08-31

[0023] The problem that the present invention aims to solve is to provide a nano nozzle that can control the contact angle between the ink injected into the nozzle and the coating layer formed on the inner surface to 45° or less by coating the inner surface of the nano nozzle with an ink-friendly component.

[0024] In addition, the nano nozzle according to the present invention can optimize the interfacial interaction between the coating layer and the injected ink, thereby enabling the ink to stably wet the inside of the nozzle.

[0025] Accordingly, it is possible to ensure the uniformity of droplets during the printing process and improve the precision of the stacking process, thereby enabling the realization of high-resolution 3D structures.

[0026] The present invention is a nano nozzle comprising a coating layer having an inner surface formed of an ink-friendly component.

[0027] In the present invention, the coating layer may be formed as a liquid coating or a vapor coating.

[0028] In the present invention, the thickness of the coating layer may be 100 nm or less.

[0029] In the present invention, the contact angle between the coating layer and the ink injected into the nano nozzle may be 45° or less.

[0030] In the present invention, the ink-friendly component may be a hydrophilic or hydrophobic component.

[0031] In the present invention, the inner diameter of the nano nozzle may be 15 nm to 5 µm.

[0032] In the present invention, the maximum value of the printing speed of the nano nozzle measured under the following conditions may be 1.5 times or more of the maximum printing speed of an uncoated nano nozzle measured under the following conditions.

[0033] [Measurement Conditions]

[0034] Inner diameter 100 nm, 25℃, relative humidity 50%, water-soluble PVA 5%(w / w) ink, pressure 10~200 kPa.

[0035] In the present invention, the maximum value of the printing speed of the nano nozzle measured under the following conditions may be 80 µm / s or more.

[0036] [Measurement Conditions]

[0037] Inner diameter 100 nm, 25℃, relative humidity 50%, PES 5% (w / w) ink dissolved in DMAC, pressure 10~200 kPa.

[0038] The nano nozzle according to the present invention has a coating layer formed on its inner surface that is coated with an ink-friendly component, thereby controlling the contact angle with the injected ink to 45° or less, which improves the spreading ability of the liquid and can improve the printing speed compared to an uncoated nano nozzle under pressure conditions.

[0039] In addition, under certain conditions, the maximum printing speed is increased by more than 1.5 times compared to the same uncoated nozzle, and droplet uniformity is ensured, which improves interlayer adhesion and enhances the surface quality of the printed object.

[0040] In addition, the maximum printing speed was measured to be over 80 µm / s under certain conditions, and consistent performance was demonstrated in repeated experiments, enabling stable output even during continuous use for a long time.

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Throughout the specification, similar parts are denoted by the same reference numerals.

[0042]

[0043] Hereinafter, specific embodiments according to the present invention will be described.

[0044]

[0045] The present invention relates to a nano nozzle comprising a coating layer having an inner surface formed of an ink-friendly component.

[0046] In the present invention, the coating layer can be formed in various ways and can be formed as a liquid coating or a vapor coating.

[0047] For example, a solution coating method in which a solution of an ink-friendly component is applied to the inner wall of a nozzle and then dried, a dip coating method in which a nozzle is immersed in a solution of an ink-friendly component and then dried, or a spin coating method in which the nozzle is rotated and applied uniformly can be used.

[0048] In addition, the above coating may be performed through plasma treatment, chemical vapor deposition (CVD), surface modification reactions, etc. Through these various coating methods, an ink-friendly component is uniformly formed on the inner wall of the nozzle, so that the contact angle with the ink injected into it can be stably controlled.

[0049] In addition, the thickness of the coating layer formed according to the ink-friendly component may be 100 nm or less, and preferably 20 nm or less.

[0050] If the thickness of the coating layer exceeds 100 nm, the coating layer becomes excessively thick, which reduces the effective inner diameter and consequently may cause problems such as limited ink ejection or increased pressure loss of the nozzle. In addition, a thick coating layer is more likely to crack or delaminate during the drying and curing process, which may reduce the durability of the coating.

[0051] Accordingly, by controlling the thickness of the coating layer to a range of 100 nm or less, the ink-friendly component is uniformly and stably formed on the inner wall, so that the contact angle with the ink injected into the nano nozzle is stably maintained, and at the same time, the effective inner diameter of the nozzle is secured, enabling smooth ink ejection and high-resolution 3D printing.

[0052] In the present invention, the contact angle between the coating layer and the ink injected into the nano nozzle may be 45° or less, and preferably 35° or less.

[0053] If the above contact angle exceeds 45°, the wettability of the ink is reduced, preventing the ink from spreading smoothly inside the nozzle, and consequently, problems may arise such as difficulty in controlling the flow rate and reduced spray stability.

[0054] In the present invention, the ink-philic component may be a hydrophilic or hydrophobic component. Specifically, the hydrophilic component may be one or more selected from the group consisting of polyvinyl alcohol (PVA), polyethylene glycol (PEG), amine-based polymers, and polymers having hydroxyl groups, and the hydrophobic component may be one or more selected from the group consisting of polyvinylidene fluoride (PVDF), polysulfone (PSF), polyethersulfone (PES), polyethylene (PE), and polypropylene (PP).

[0055] In the present invention, the ink-friendly component and the ink injected into the nano nozzle may be hydrophilic or hydrophobic, and any component that maintains a contact angle of 45° or less between the formed coating layer and the ink can be used without limitation.

[0056] Specifically, the ink used in the present invention is also not particularly limited in its properties, whether hydrophilic or hydrophobic. That is, the nano nozzle of the present invention can be applied regardless of the polarity of the injected ink.

[0057] For example, the ink injected into the nano nozzle according to the present invention may be prepared as follows: 1) 5% (w / w) of polysulfone dissolved in a dimethylacetamide solvent, 2) 5% (w / w) of polyvinyl alcohol dissolved in a water (H₂O) solvent, and 3) 5% (w / w) of polyethersulfone dissolved in an N-methyl-2-pyrrolidone solvent.

[0058] Accordingly, the nano nozzle according to the present invention can be stably applied to various solvent-based and polymer-based inks, and can achieve uniform droplet formation and excellent printing performance regardless of the hydrophilicity or hydrophobicity of the ink.

[0059] The weight-average molecular weight of the polymer included in the ink-friendly component and ink component used in the present invention may be in the range of 1,000 to 500,000 g / mol.

[0060] If the weight-average molecular weight is less than 1,000 g / mol, the viscosity is low, which may result in unstable droplet formation. On the other hand, if it exceeds 500,000 g / mol, solubility decreases and viscosity increases excessively, which may cause problems with smooth nozzle discharge. Therefore, it is desirable to use a polymer having a weight-average molecular weight within the above range.

[0061] In the present invention, the inner diameter of the nano nozzle may be 15 nm to 5 µm. If the inner diameter of the nozzle is less than 15 nm, the nozzle diameter becomes excessively small, causing the surface tension and capillary force of the liquid to act predominantly, which may result in unstable droplet formation and difficulty in controlling the flow rate. Additionally, if the viscosity of the ink is high or the polymer content is high, the liquid may not pass through the nozzle, and clogging may occur frequently.

[0062] Conversely, if the inner diameter of the nozzle exceeds 5 μm, fine droplet control becomes impossible as the nozzle diameter increases, and high-resolution printing becomes difficult as the size of the ejected droplets increases. In addition, the droplet formation becomes rough, which reduces interlayer precision and may cause problems such as a decrease in the surface quality of the 3D printed product.

[0063] In the present invention, the maximum value of the printing speed of the nano nozzle measured under the following conditions may be 1.5 times or more of the maximum printing speed of the uncoated nano nozzle measured under the following conditions, and preferably 1.5 to 3 times.

[0064] [Measurement Conditions]

[0065] Inner diameter 100 nm, 25℃, relative humidity 50%, water-soluble PVA 5% (w / w) ink, pressure 10~200 kPa.

[0066] In addition, in the present invention, the maximum value of the printing speed of the nano nozzle measured under the following conditions may be 80 µm / s or more, and preferably 90 to 110 µm / s.

[0067] [Measurement Conditions]

[0068] Inner diameter 100 nm, 25℃, relative humidity 50%, water-soluble PVA 5% (w / w) ink, pressure 10~200 kPa.

[0069] In addition, in the present invention, the maximum value of the printing speed of the nano nozzle measured under the following conditions may be 1.5 times or more of the maximum printing speed of the uncoated nano nozzle measured under the following conditions, and preferably 1.5 to 3 times.

[0070] [Measurement Conditions]

[0071] Inner diameter 100 nm, 25℃, relative humidity 50%, Polysulfone 5% (w / w) ink dissolved in Dimethylacetamide, pressure 10~200 kPa.

[0072] In addition, in the present invention, the maximum value of the printing speed of the nano nozzle measured under the following conditions may be 80 µm / s or more, and preferably 90 to 110 µm / s.

[0073] [Measurement Conditions]

[0074] Inner diameter 100 nm, 25℃, relative humidity 50%, Polysulfone 5% (w / w) ink dissolved in Dimethylacetamide, pressure 10~200 kPa.

[0075] Accordingly, the nano nozzle of the present invention includes a coating layer formed on its inner surface with an ink-friendly component, thereby stably controlling the contact angle with the ink injected into the nano nozzle and ensuring uniformity of ink ejection, so it can be applied to 3D printing technology in various fields. More specifically, the nano nozzle of the present invention may be a nozzle for 3D printing, and more preferably, may be a 3D printing nozzle for manufacturing membranes.

[0076] In particular, in the field of bioprinting, it is applicable not only to hydrophilic materials such as cells, proteins, nucleic acids, and hydrogels, but also to bioinks based on hydrophobic media. Therefore, the nano nozzle of the present invention can be usefully utilized in the life science and medical fields, such as fabricating scaffolds for tissue engineering, regenerating customized tissues, and fabricating artificial organs while maintaining cell viability.

[0077] In addition, it can be applied to the field of printing electronic materials and functional materials. For example, since it can stably eject not only hydrophilic inks such as silver nanoparticles, conductive polymers (PEDOT:PSS, etc.), insulating polymers, and optical materials, but also hydrophobic organic solvent-based inks, it is suitable for fabricating micro-patterns for microelectrodes, electronic circuits, sensors, and displays. In particular, by enabling the formation of high-resolution nano-patterns, it can contribute to the fabrication of flexible electronic devices, wearable devices, and biosensors.

[0078] Furthermore, it can be applied in the fields of fabricating micro- and nano-structures and manufacturing microfluidic devices. Since the nano-nozzle of the present invention can control the inner diameter from tens of nanometers to several micrometers, it can be utilized in various microfabrication processes, such as forming flow channels for microfluidic chips, fine patterns for optical devices, and fabricating nanoparticle-based catalyst structures. In particular, since the reproducibility of droplet ejection is ensured, repetitive high-precision patterning is possible, making it suitable for realizing precise structures at the micro- and nano-scale.

[0079] Consequently, the nano nozzle of the present invention fundamentally improves the droplet instability, non-uniform ejection, and nozzle clogging phenomena that occurred in conventional technology, while providing versatility capable of handling both hydrophilic and hydrophobic inks. Therefore, the present invention can be considered an important technical means that can contribute to the advancement of 3D printing technology in advanced application fields such as biomaterials, electronic devices, and microfluidic devices.

[0080] The present invention also relates to a 3D printer comprising the nano nozzle. The 3D printer may include a printing control unit driven based on digital design data, an ink storage unit that stores ink, a pressure control unit that supplies ink to the nano nozzle, and a stage or driving module that controls the position and movement of a discharged droplet.

[0081] The nano nozzle employed in the above 3D printer has its inner surface coated with an ink-friendly component, so the interfacial affinity with ink is improved, allowing for stable droplet ejection in response to pressure changes. As a result, the uniformity of interlayer bonding during printing is ensured, and the precision of the microstructure is improved.

[0082] In addition, the 3D printer of the present invention is applicable not only to hydrophilic polymer inks such as PVA water-based ink, PEG solution, amine-based polymer solution, and biocompatible hydrogel, but also to hydrophobic polymer inks such as polysulfone and polyethersulfone. Therefore, the nano nozzle of the present invention can be advantageously utilized in various application fields such as bioprinting (cell patterning, fabrication of scaffolds for tissue engineering), electronic material printing (conductive patterns, fabrication of sensors), and microfluidic chip manufacturing.

[0083]

[0084] The present invention will be explained below through preferred embodiments.

[0085]

[0086] Examples

[0087] A glass nano nozzle with an inner diameter of 100 nm was prepared. To modify the inner surface of the prepared nano nozzle to be ink-friendly, an aqueous solution of polyvinyl alcohol (PVA, weight-average molecular weight 100,000 g / mol) (5% (w / w)) was introduced into the nozzle and then removed. Subsequently, the nozzle was dried at 120 °C for 30 minutes to form a PVA coating layer on the inner surface. Upon confirmation through transmission electron microscopy (TEM) and surface analysis, the formed coating layer was found to be uniformly applied across the entire inner wall, with a thickness of approximately 10 nm.

[0088]

[0089] Comparative example

[0090] A nano nozzle with the same specifications as the above example was used as is without separate surface treatment.

[0091]

[0092] Experimental Example 1

[0093] The contact angle between the coating layer of the nano nozzle of the examples and comparative examples and the 5% (w / w) PVA ink dissolved in water and the 5% (w / w) Polysulfone ink dissolved in Dimethylacetamide was measured by the following method.

[0094] Specifically, the contact angle was measured using an optical goniometer with a borosilicate plate specimen according to ASTM D5946 (Method for measuring contact angle between plastic film and liquid). The measurement was performed at 25°C and 50% relative humidity, with a droplet volume of 2.0 μL. The plate specimen was immersed in an aqueous solution (5% (w / w)) of polyvinyl alcohol (PVA, weight-average molecular weight 100,000 g / mol), similar to the inner surface of the nano nozzle, and then dried at 120°C for 30 minutes to form a PVA coating layer on the inner surface, with a thickness of approximately 10 nm.

[0095]

[0096] As a result, the contact angle before coating with water-soluble PVA 5% (w / w) ink was θ o = 70°, and the contact angle after coating is θc = 30°.

[0097] In addition, the contact angle before coating with polysulfone 5% (w / w) ink dissolved in dimethylacetamide is θ o = 70°, and the contact angle after coating is θc = 30°.

[0098]

[0099] Experimental Example 2

[0100] Water-soluble PVA 5% (w / w) ink and Dimethylacetamide-soluble Polysulfone 5% (w / w) ink were injected into the nano nozzles of the examples and comparative examples, respectively, and the printing speed was measured while varying the pressure to 0, 10, 50, 100, and 200 kPa under conditions of a temperature of 25°C and a relative humidity of 50%.

[0101] The printing speed was measured by performing 10 horizontal line prints for 1 minute under each condition and measuring based on the maximum speed at which stable printing is possible without droplet interruption.

[0102] Each measurement was repeated five times under the same conditions, and the average value was used as the result. The results are shown in Tables 1 and 2 below. Table 1 shows the printing speed for 5% (w / w) PVA ink dissolved in water, and Table 2 shows the printing speed for 5% (w / w) Polysulfone ink dissolved in Dimethylacetamide.

[0103]

[0104] Injection pressure (kPa) Example (μm / s) Comparative Example (um / s) 09640109640509840100994020010240

[0105] Injection pressure (kPa) Example (μm / s) Comparative Example (um / s) 09640109640509840100994020010240

[0106] Referring to Tables 1 and 2 above, it can be seen that the nano nozzle with a coated inner surface (Example) has a maximum printing speed more than twice that of the nano nozzle without coating (Comparative Example).

[0107] In addition, it can be confirmed that the nano nozzle with an inner surface coated (Example) has a maximum measured printing speed of 90 µm / s or more.

[0108] Furthermore, it can be confirmed that the same effect is exhibited for hydrophilic or hydrophobic inks.

[0109]

[0110] The present invention can provide a nano nozzle capable of controlling the contact angle between the ink injected into the nozzle and the coating layer formed on the inner surface to 45° or less by coating the inner surface of the nano nozzle with an ink-friendly component.

Claims

1. A nano nozzle comprising a coating layer formed of an ink-friendly component on its inner surface.

2. In Paragraph 1, A nano nozzle in which the coating layer is formed as a liquid coating or a vapor coating.

3. In Paragraph 1, A nano nozzle having a coating layer thickness of 100 nm or less.

4. In Paragraph 1, A nano nozzle having a contact angle of 45° or less between the coating layer and the ink injected into the nano nozzle.

5. In Paragraph 1, A nano nozzle in which the above-mentioned ink-philic component is a hydrophilic or hydrophobic component.

6. In Paragraph 1, A nano nozzle having an inner diameter of 15 nm to 5 µm.

7. In Paragraph 1, The above nano nozzle is a nano nozzle in which the maximum value of the printing speed measured under the following conditions is 1.5 times or more the maximum printing speed of an uncoated nano nozzle measured under the following conditions: [Measurement Conditions] Inner diameter 100 nm, 25℃, relative humidity 50%, water-soluble PVA 5% (w / w) ink, pressure 10~200 kPa.

8. In Paragraph 1, The above nano nozzle is a nano nozzle having a maximum printing speed of 80 µm / s or more as measured under the following conditions: [Measurement Conditions] Inner diameter 100 nm, 25℃, relative humidity 50%, PES 5% (w / w) ink dissolved in DMAC, pressure 10~200 kPa.