Open surface solution feeding mechanism for high capacity electrospinning system

Abstract

The invention is related to an innovation on the solution feeding mechanism, which is the most important part in electrospinning and electrospraying systems (200). The solution feeding structure is the most critical part of electrospinning systems (200). The type, functionality, scale and efficiency of the process are directly related to this structure. The innovative solution developed with the invention is related to an open- surface spinneret structure and the dynamic mechanism that feeds solution to it.

Description

[0001] OPEN SURFACE SOLUTION FEEDING MECHANISM FOR HIGH CAPACITY ELECTROSPINNING SYSTEM

[0002] Technical Field

[0003] Invention, electrospinning and electrospraying (electrospinning, electro-spinning, electro-production) used in the production of nanofiber and nanoparticle materials are also widely used expressions such as.) is about an innovation made on the hardware related to the nutrition of the production material, which is the most critical part in their system and constitutes the most important part in terms of the function and efficiency of the system in defining the process method.

[0004] The invention relates to a solution feeding system that provides the opportunity to produce nanofibers faster compared to needle-based feeding systems, where the nanofiber coating has a high uniformity throughout the production area, advantageous in terms of ease of operation. In this system, pre-process preparation studies and postprocess cleaning-maintenance operations are minimized.

[0005] State of Art

[0006] Nanofibers, according to the most common expression in the literature, can be called fibers below the orders of microns. Nanofibers, with their excellent properties such as large surface area, high porosity and small pore size, are a very interesting material form for the development of functional products that are technically more advantageous than conventional alternatives for a wide variety of fields.

[0007] The main application areas of nanofibers are high-performance filters, personal protective equipment, performance textiles, medical textiles (wound covering materials, etc.), controlled drug release applications, applications for tissue engineering, separators used in li-ion batteries, electrodes in hydrogen fuel cells can be exemplified as sensors.

[0008] Many different methods are mentioned in the literature for the production of nanofibers. However, the most suitable method for industrial scale production is the electrospinning method. Features such as low production costs, low need for qualified personnel in production, ability to diversify product features with simple process optimizations, machinability of a wide variety of material groups, and the possibility of producing composite or bicomponent structures can be considered as examples of the advantages of the electrospinning process..

[0009] The main disadvantage of the electrospinning process, which is a relatively new production method compared to conventional textile technologies, is the slow production speed. To improve this situation, device systems have been developed with different configurations. In order to improve the production speed, improvements in the mechanism of the system in which the process is carried out, increasing the applied voltage value and different configurations of solution feeding systems have been tried.

[0010] Electrospinning is a versatile technique for producing nanofibers from a variety of materials. The solution feeding mechanism is a very important aspect of electrospinning systems and different systems can be categorized based on how the solution is supplied. We can divide the industrial electrospinning systems available on the market into two main groups, in terms of solution feeding mechanisms, as nozzlebased or needle-based systems and needleless, open surface systems. Although nozzle systems are similar to each other in terms of solution feeding and distribution, the main differences are related to the design and arrangement of the nozzles. Nozzleless systems can be found in different configurations. This equipment used to distribute the solution to the electric field in an electrospinning system with or without a nozzle can be called "nozzle".

[0011] Needle-based electrospinning systems are a type of electrospinning device that uses single or multiple needles to feed the polymer solution for nanofiber production. This method is widely used in both research and industrial settings. In needle-based electrospinning, a needle connected to a syringe containing polymer solution, either directly or via a solution delivery coupling, is used to deliver the solution to the target surface or collector. A high voltage is applied between the needle and the collector, creating a Taylor cone and launching a thin jet of polymer solution that is stretched and solidified to form nanofibers. When the jet collector reaches the surface, it solidifies and adheres and a film is obtained.

[0012] It is quite easy to operate a single-needle electrospinning device, but compared to more complex systems, this method is insufficient in terms of production speed, in terms of the size of the produced membrane area, in short, although it is a simple solution for scientific research applications, it is insufficient for industrial purposes, that is, high capacity production purposes.

[0013] As efficiency criteria of the nozzle configuration used; It is possible to list issues such as high production speed, obtainability of homogeneous nanofiber morphology, obtainability of homogeneous nanofiber coating surface, constancy of solution viscosity during production, avoidance of problems such as clogging that would prevent the continuity of production. Although the multi-needle electrospinning method has the advantages of accelerating nanofiber production and using various polymer solutions simultaneously, it may encounter various disadvantages and operational problems. The first disadvantage of this method is system complexity. Simultaneous use of multiple needles complicates the structure in the system and makes installation more difficult. It is important that operators are well trained and provide regular maintenance to manage this complexity.

[0014] Among the operational problems is flow rate irregularity. Irregularities in the flow rate of the polymer solution through each needle can cause variations in the diameter and morphology of the nanofibers. Electric fields generated by neighboring needles can interact with each other, leading to irregularities on jet formation and fiber deposition. During production, needles may become clogged, disrupting the flow of the solution. Clogging of different needles is an uncontrollable and uncorrectable problem during the operation.

[0015] The time required at the beginning of the process and at the end of production is long. Cleaning the solution delivery system and changing needles at the end of each production is a difficult process. The excess labor required may cause an increase in costs.

[0016] Needleless electrospinning, also known as free surface electrohydrodynamic jetting, is a process that destabilizes polymer droplets under applied electrostatic forces, triggering liquid polymer solutions and thus producing nanofibers. As a result, jets are formed by the stretching and thinning of the droplet-like structures formed on the surface of the polymer solution. At the tip of the polymer solution, a cone structure (Taylor cone) is produced from which jets of charged particles are launched. The needle electrospinning technique can create only one Taylor cone per needle; However, in needleless spinning, the formation of more than one Taylor cone occurs. This allows rapid production of nanofibers in high quantities by increasing the number of polymer jets formed (Raja, V, 2023).

[0017] Purpose of the Invention

[0018] The issues targeted by the invention subject to the patent to be applied for are high production capacity, controllable solution distribution, and obtaining appropriate jet distribution that will allow homogeneous nanofiber coating.

[0019] The system has been developed to be used with high production capacity electrospinning systems that enable roll-to-roll production.

[0020] We can simply describe the mechanism of the electrospinning process as follows: The polymer in solution (usually the polymer solution to be used in nanofiber production) is fed through a pipe. A conductive nozzle is located at the point where the solution is released (it can be a standard syringe needle, a specially designed nozzle, or the structures mentioned above). A certain voltage is applied to this level with a high voltage power supply. The surface of the polymer droplet becomes electrically charged. There is (usually) a grounded conductive collector opposite the nozzle to which electrical charge is applied. By increasing the amount of voltage, the surface tension of the liquid is overcome by the applied voltage and the solution moves towards the collector as a very fine jet. The polymer jet first follows a stable and then an unstable (spiral) path. Meanwhile, the solvent in the solution is removed and the polymer collects on the collector surface in the form of nanofibers.

[0021] With the invention, the solution is fed into a millimeter-sized slot opened on a flat metal structure of a certain length. With the high voltage power supply, static electricity (approximately 70 kV) provided by the high voltage power supply is applied to this flat metal structure. The dimensions of the slot structure were chosen appropriately in order to form a jet from the polymer solution (Approximately 2 mm in width and 2 mm in depth). The polymer solution into this solution chamber is supplied from above by a plastic head and a dynamic feeding head moving along the slot structure. When the process is optimized, the solution turns into a jet seconds after it is transferred into the slot and the electrospinning process takes place.

[0022] With the invention, a significantly higher production rate will be achieved in all polymeric solutions compared to conventional needle systems.

[0023] Another aim of the invention is to obtain a homogeneous coating by providing uninterrupted jet formation (along the length of the feeding nozzle) along the high voltage structure over the solution fed into the slot.

[0024] One of the important advantages of the invention is that the solution feeding rate can be measured as the solution is transferred into the slot in a controlled manner with a special transmission structure; In this direction, it will be possible to dimension the production, and the solution feeding rate, which is an important data for the process, can be followed numerically.

[0025] With the invention, the preparations that need to be made before starting production, that is, the hose connections that need to be made before starting production, are very easy and do not take much time; Once production is complete, cleaning the system components is much simpler than the needle system.

[0026] In order to fulfill all the purposes mentioned above and which can be derived from the detailed description, the invention is an open-surface feeding mechanism used in electrospinning systems, which allows roll-to-roll production in the production of nanofiber and nanoparticle materials, the main body connected to the electrospinning system,

[0027] - at least one nozzle positioned on the main body on the horizontal axis and applying static electricity with a high voltage power source to the polymeric solution fed into it, which enables the polymeric solution to turn into a jet and the electrospinning process to be carried out,

[0028] - slot that opens on the flat along its length and allows the feeding of polymeric solution into the flat,

[0029] - distribution module that feeds the polymeric solution from the electrospining system to each level by moving along the slot on the level,

[0030] - solution transfer head that transfers the polymeric solution fed from the distribution module into the slot,

[0031] - it is related to the fact that it contains a linear motion module that moves the distribution module along the slot on a straight line.

[0032] The structural and characteristic features and all the advantages of the invention will be understood more clearly thanks to the figures given below and the detailed explanation written with references to these figures. For this reason, the evaluation must be made by taking these figures and detailed explanation into consideration.

[0033] Figures to Help Understand the Invention

[0034] Figure la: The subject of the invention is the perspective view of the feeding mechanism.

[0035] Figure lb: The subject of the invention is the top view of the feeding mechanism.

[0036] Figure 2: The subject of the invention is the appearance of the feeding mechanism on the electrospinning system.

[0037] Figure 3: The subject of the invention is a perspective view of the feeding mechanism from another angle.

[0038] Figure 4: This is the detail view of the distribution module and solution transfer head of the feeding mechanism that is the subject of the invention.

[0039] Explaining Part References

[0040] 10. Main body or Process Table

[0041] 20. level 21. Slot

[0042] 30. Reservoir

[0043] 40. Distribution module

[0044] 50. Solution transfer head

[0045] 60. Linear motion module

[0046] 100. Feeding mechanism

[0047] 200. Electrospining system

[0048] Detailed Description of the Invention

[0049] In this detailed explanation, the preferred alternatives of the feeding mechanism (100) subject to the invention are explained only for a better understanding of the subject and in a way that does not create any limiting effect.

[0050] In Figures la and lb, an overview of the feeding mechanism (100), which is the subject of the invention, is given. According to this, the feeding mechanism (100) is in the most basic state; the main body (10), which is connected to the electrospining system (200) and on which the levels are placed, which also carries the high voltage device, is positioned on the horizontal axis on the main body (10) at a certain distance from each other and fed into the polymeric solution via a slot (21) that opens along its length, applying static electricity to the polymeric solution in a flat form, which allows the polymeric solution to turn into a jet and perform the electrospinning system (200), level

[0051] (20) reservoir (30) that collects the transferred excess polymeric solution , distribution module (40) that feeds the polymeric solution from the pumping part of the electrospining system (200) to each level (20) by moving along the slots (21) on the levels (20), solution transfer header (50) located on the lower surface of the distribution module (40) and transfers the polymeric solution processed on the levels to the slots

[0052] (21), linear motion that moves the distribution modules (40) along the slots (21) on the levels (20) the Linear motion module (60).

[0053] The feeding mechanism (100), which is the subject of the invention, is connected to the electrospining system (200) by means of the main body (10), as shown in Figure 2. It is positioned on the main body (10) in question, at least one plane (20) on the horizontal axis. Level (20) is made of metal and has a flat form. On the level (20), a slot (21 ) has been opened along its length. The slot (21) here is the most important part of the developed electrospinning method. The polymer solution is fed into this slot and electrospinning jets are formed here. The slot depth is on average 2 mm and the height is on average 2 mm. The electrospinning zone on which the slot is processed, the metal rods with a width length are called level (20). A high voltage is supplied to these levels (20) and thus an electrostatic effect is achieved.

[0054] Static electricity is applied to the level (20) with a high voltage power supply, and the polymeric solution fed into the slot (21) is converted into a jet and the electrospining process is performed. The supply of the polymeric solution to the slot (21) is provided by the distribution module (40), which feeds the polymeric solution coming from the electrospining system (200) via peristaltic pumps and hoses to each level (20) by moving along the slot (21) on the levels (20) as shown in Figure 3.

[0055] There are small round reservoirs (30) at both ends of the layout, i.e. on the right and left sides of the slots (21). During the solution supply, the module that distributes the solution waits for a certain period of time at both ends. At this time, although the pumping has been stopped, a small amount of flow occurs and the polymer solution is transferred to the reservoir by the return system from the reservoir (30).

[0056] The solution is delivered to the distribution modules (40) by using peristaltic pumps located in the body of the machine and hoses of the appropriate diameter. The distribution module feeding each level is mounted to the linear motion module (60) at the base. The titles that empty the solution into the slots are connected to these parts.

[0057] The system is designed to be able to produce faster on an industrial scale than conventional systems. The operational difficulty of the system is again quite low compared to conventional needle-based systems.

[0058] The polymer solution is transferred towards the distribution modules (40) by the pump. In this transfer, a hose that will not be affected by the chemicals in the solution is used. Feeding flow rate can be controlled by machine automation. Then, the solution is fed into the slots (21) by the solution transfer header (50) in a controlled manner. This linear motion module (60) distributes the solution homogeneously into the slot (21) with periodic movements from one end to the other along the level (20). With the automation system of the machine, the flow rate at which the solution is fed, the movement speed of the feeding mechanism (100) through the slots and the feeding time at both ends can be adjusted. The process starts with static electricity applied to the level (20). The resulting nanofibers begin to collect in the collector directly opposite the structure numbered and film formation is observed.

[0059] The mechanism described above is located in an industrial-scale electrospinning system. In these systems, the fabric (the substrate material on which the nanofiber is coated) is coated while it is transferred from roll to roll and passes through the electrostatic zone. The fabric wrapping and release system may be integrated into the chassis or separate, depending on the model of the machine.

Claims

CLAIM1. It is the feeding mechanism (100) used in electrospinning systems (200), which allows high-capacity roll-to-roll production in the production of nanofiber and nanoparticle materials, and its characterized by; i. the main body (10), which serves as a table carrying the solution feeding mechanism connected to the electrospinning system (200) and carries all the equipment for this purpose, ii. at least one plane that is positioned on the main body or process table (10) on a horizontal axis and fed into the polymeric solution by applying static electricity with a high voltage power source to the polymeric solution that turns the polymeric solution into a jet and enables the electrospinning process to be performed, which is one of the critical parts of this invention and has been developed as an alternative to the conventional needle system (20), iii. slot (21), which opens on the level (20) along its length and provides the supply of polymeric solution to the flat (20), where electrospinning jets are formed through the solution (20), iv. Distribution module (40) that moves through the slot (21) on the level (20) and feeds the polymeric solution coming from the pumping structure that provides solution transfer in the electrospinning system (200) to each level (20), v. Solution transfer head (50), which transfers the polymeric solution fed from the distribution module (40) into the slot (21), vi. It contains a linear motion module (60) that moves the distribution module (40) along the slot (21) on the level (20).

2. As mentioned in Claim 1; It is a feeding mechanism (100)and its characterized by; that it contains a reservoir (30) located at both ends of the mentioned level (20) and collecting excess polymeric solution transferred to the level (20).

3. As mentioned in Claim 1; It is a feeding mechanism (100)and its characterized by; that the mentioned level (20) is made of metal material in flat form.

4. As mentioned in Claim 1; It is a feeding mechanism (100)and its characterized by; that the mentioned distribution module (40) contains a solution transfer head (50) on its lower surface, the height of which can be adjusted to be positioned on the slot (21) according to the behavior of the polymeric solution.

5. As mentioned in Claim 1; It is a feeding mechanism (100)and its characterized by; that it contains a distribution module that is connected to the mentioned linear motion module (60) and moves from one end to the other along the slot (21) on the level (20) through the linear motion module (60).

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