Medical hydrophobic filter production method

Abstract

The invention is related to a porous hydrophobic filter obtained by sintering polyethylene and nano crystalline cellulose, which will be used in the covers of suction bags, preventing contamination by not allowing the passage of microorganisms larger than 0.2-0.4 microns, and will stop the suction by acting as a check-valve when the bag is full, preventing overflow and backflow.

Description

[0001] MEDICAL HYDROPHOBIC FILTER PRODUCTION METHOD

[0002] Technical Field

[0003] The invention relates to a medical hydrophobic filter.

[0004] The invention particularly relates to a method of producing a hydrophobic filter that is used in aspiration bags (suction bags) used in hospitals in aspiration processes that allow the respiratory system secretions of patients to be removed with a vacuum device operating under negative pressure, and that only allows air to pass through under vacuum and does not allow liquid to pass through.

[0005] State of the Technique

[0006] Today, suction bags are used instead of jars to ensure medical waste safety. Aspirator bags are made of thermoplastic or polycarbonate and are disposable (Figure 1 ). They provide a closed system for hygienically collecting and disposing of fluids accumulated in body cavities. Thus, they protect against infection risks that may occur during transportation, emptying or cleaning. When the suction bag is full, the automatic locking mechanism is closed and it is thrown into the medical waste bin. There should usually be an integrated, double-stage filter at the vacuum source inlet of the suction bag. These special filters are hydrophobic filters that will prevent the passage of liquid and microorganisms into the vacuum system in the bag. Thanks to these filters, it will prevent contamination by not allowing microorganisms larger than 0.2-0.4 microns to pass through, and when the bag is full, it will act as a check-valve, stopping the suction and preventing overflow and backflow.

[0007] In Figure 1 , the general view of the suction bag used in the medical field and the equipment that forms it are given. The internal view of the suction cover (10) is given and the hydrophobic filter (20) which is the subject of the invention and is located inside is shown. The hydrophobic filter (20) is a special filter that prevents the passage of bacteria and viruses at the vacuum suction end and stops the suction when the bag is full. All special products and accessories are always compatible with other medical products and are calibrated to work together with the container attachment point size (30). The serial connection point (40) allows the suction capacity to be expanded up to 36 liters, the largest volume on the market. The single patient connector (50) eliminates the risk of faulty connection and makes liner changes fast and safe. It also includes a hose for vacuum (60), a vacuum adjustment valve (70), and suction bag (80). The aspiration container or canister (90) forms the entirety of the aspiration system. Suction bags generally provide the advantage of protection from possible infections originating from the hospital environment. It provides convenience and practical application in the work of the user staff and team. The connection type and assembly are easy. When the bag is full, it is easy to change and does not take time. It eliminates the risks of splashing and spilling. It helps to maintain hospital hygiene. It provides an advantage in terms of controlled medical waste disposal. Since it is a closed system, it prevents odor spreading to the services. It can be easily used by the anesthesia and operation team in operating rooms. It can generally be used in similar liquid aspiration processes with a vacuum source connection.

[0008] Although the hydrophobic filter has a million-dollar market in the world in the medical field, since it is not yet domestically produced in our country, it can meet the domestic market demand with imports. Since the suction bag and other components are made of a single type of plastic, they can be easily shaped and products can be obtained. The filter is a composite structure that combines multiple features such as being resistant to vacuum, stopping air permeability in contact with liquid and preventing the passage of microorganisms. For this reason, this filter, which has not yet been produced with R&D support, is imported and only increases the cost of the suction bag system on its own, and causes it to be unable to compete with existing foreign companies. For this reason, low-cost hydrophobic filters that do not allow the passage of microorganisms larger than 0.2-0.4 microns, prevent contamination, and stop the suction by acting as a check-valve when the bag is full and prevent overflow and backflow are needed.

[0009] The national utility model application numbered TR2016 / 07075 discloses a canister containing a disposable EVA (ethyl vinyl acetate) mixed PE (polyethylene) material aspiration bag. However, the filter features stated to be at the vacuum suction end are not specified.

[0010] In the European patent numbered EP2755696B1 , a low-pressure canister is described, which includes a canister body with a liquid reservoir, an inlet port for receiving liquid from the patient, and an integrated hydrophobic filter formed on the side or top of the canister body. It is stated here that the integrated hydrophobic filter has multiple pores inside the canister body that are sealed with a hydrophobic coating such as PTFE. However, the manufacturing method is not disclosed.

[0011] As a result, due to the above-mentioned drawbacks and the inadequacy of the existing solutions, a development in the relevant technical field has become necessary.

[0012] Purpose of the Invention

[0013] The invention is inspired by the current situation and aims to solve the above-mentioned negativities. The main purpose of the invention is to provide an economical hydrophobic filter and production method to be used in the covers (lids) of aspiration bags (suction bags), which will prevent contamination by not allowing the passage of microorganisms larger than 0.2-0.4 microns and will stop the suction by acting as a check-valve when the bag is full and prevent overflow and backflow. Within the scope of the invention process, it is aimed to provide a new production method in the technical field with the PE / NCC hydrophobic composite filter, which will be completely domestic and newly produced, and to reduce our country's foreign trade deficit by reducing external dependency with the use of the new economic products obtained.

[0014] One purpose of the invention is to provide a hydrophobic filter production method that will provide air flow thanks to its porous PE / NCC composite structure, while showing the hydrophobic feature of polyethylene and prevent liquid passage by swelling thanks to the hydrophilic feature of nano crystalline cellulose when in contact with liquid.

[0015] In order to fulfill the above purposes, the invention is a hydrophobic filter production method that will prevent contamination by not allowing the passage of microorganisms to be used in the covers of suction bags and will stop the suction by acting as a check valve when the bag is full and prevent overflow and backflow; comprising the following process steps: i. mixing predetermined amounts of nanocrystalline cellulose and polyethylene in a solvent, ii. removing the solvent and drying the mixture, iii. grinding the dried nanocrystalline cellulose and polyethylene mixture to obtain a homogeneous powder mixture, iv. placing the homogeneous powder mixture in a mold in the desired filter shape and pressing it under a temperature and pressure close to the melting temperature, v. removing the resulting hydrophobic filter from the mold.

[0016] According to an embodiment of the invention, in the process step (i), 1 -50% by weight nanocrystalline cellulose and 50-99% by weight polyethylene, preferably 1 -10% by weight nanocrystalline cellulose and 90-99% by weight polyethylene are used.

[0017] According to an embodiment of the invention, in the process step (i), nanocrystalline cellulose and polyethylene are added to an alcohol solvent and mixed at room conditions until the solvent completely evaporates.

[0018] According to an embodiment of the invention, in the process step (ii), it is dried at 50eC for preferably 24 hours. According to an embodiment of the invention, in the process step (iii), it is mixed in a ball mill to prevent phase separation and / or maleic anhydride-derived compatibilizers are used in the mixing.

[0019] According to an embodiment of the invention, in the process step (iv), it is pressed at a temperature of 120-180°C, preferably 130-150°C, at a pressure of 0.5-1 psi, preferably for 5- 30 minutes.

[0020] According to one embodiment of the invention, at least one polyethylene from the Polyethylene (PE) group with a wide molecular weight range is used in the process step (i).

[0021] According to one embodiment of the invention, at least one polyethylene selected from low density polyethylene (LDPE), High Density Polyethylene (HDPE), Ultra high molecular weight polyethylene (UHMWPE) is used in the process step (i).

[0022] According to one embodiment of the invention; nano crystalline cellulose comprising cellulose crystals with a diameter of 5 to 500nm is used in the process step (i).

[0023] Sintered polyethylene nano crystalline cellulose composite hydrophobic filters comprising pores with dimensions below 0.2pm produced according to any of the above-mentioned embodiments and suction bags comprising these filters are also within the scope of the invention.

[0024] The structural and characteristic features and all advantages of the invention will be understood more clearly thanks to the figures given below and the detailed explanation written by making references to these figures, and therefore the evaluation should be made by taking these figures and the detailed explanation into consideration.

[0025] Description of Figures

[0026] Figure 1 . General representation of the suction bag and equipment.

[0027] Figure 2. Schematic representation of the PE / NCC hydrophobic filter production method process steps (a. mixing, b. drying, c. hot press, d. final product).

[0028] Figure 3. SEM images of the PE / NCC composite filter, which is an example of the invention (a. image in dry state, b. image after contact with water)

[0029] Description of References

[0030] 10 Suction bag cover

[0031] 20 Hydrophobic filter 30 Container attachment point size

[0032] 40 Serial connection point

[0033] 50 Single patient connector

[0034] 60 Vacuum tube

[0035] 70 Vacuum adjustment valve

[0036] 80 Suction bag

[0037] 90 Suction container (Canister)

[0038] Detailed Description of the Invention

[0039] In this detailed description, the preferred embodiments of the medical hydrophobic filter, which is the subject of the invention, are explained only for a better understanding of the subject.

[0040] The invention relates to a hydrophobic filter production method that will prevent contamination by not allowing microorganisms larger than 0.2-0.4 microns to pass through to be used in covers of suction bags and will stop the suction by acting as a check-valve when the bag is full and prevent overflow and backflow. The hydrophobic filter obtained is pressure-resistant, porous and has a composite structure that allows air transmission under vacuum but cuts off air flow when in contact with liquid, and the dimensions of the pores it contains are below 0.2pm.

[0041] Table 1 . Inventive hydrophobic filter raw material composition

[0042] Polyethylene, which is selected as the raw material of the invention, is a polyethylene group that has very important features such as high impact resistance, high wear resistance and low friction coefficient, self-lubrication, resistance to corrosion and chemicals and has a molecular weight of millions (2-6 million). Due to these features, it is used in many industrial fields such as electricity, ship, automotive, chemistry, metallurgy, food, military, coal and construction. In addition to these fields, it is also used in medicine for various purposes, such as hip bone and backbone implant applications. Polyethylene (PE) types selected in a wide molecular weight range can be used in the production of the hydrophobic filter subject to the invention, considering its hydrophobic structure and molecular weight suitable for sintering and forming porous membranes. Low density polyethylene (LDPE), High Density Polyethylene (HDPE), Ultra high molecular weight polyethylene (UHMWPE) are among the usable PE types.

[0043] Cellulose nanocrystals are an alternative to synthetic reinforcement agents in the production of composite materials, contributing to the development of the mechanical and barrier properties of the material, and a renewable material that is self-degradable in nature. NCC, which contains cellulose crystals with a diameter of 5 to 500nm, was selected in the invention considering its hydrophilic feature and nanostructure and its ability to form high homogeneity composites. Within the scope of the invention, hydrophobic PE, which swells when in contact with liquid and prevents liquid passage, is mixed in the amounts specified in Table 1 and composites are prepared through a sintering process. By performing the sintering process at 120-180 °C, more preferably 130-150 °C and 5-30 minutes, hydrophobic filters that are permeable to air and impermeable to liquid can be produced under high vacuum. The hydrogen bonds between the molecules of NCC provide the necessary strength and hardness to the structure. PE / NCC mixtures were taken at certain ratios, mixed into a homogeneous mixture in a mechanical mixer and placed in previously prepared filter molds. Then, the powdered mixture was exposed to a temperature close to the melting temperature of the materials for a certain period of time using the sintering technique. Thus, starting from the points where the particles touch each other, they were fused, reaching the desired pore sizes and gaining antibacterial properties by preventing the passage of microorganisms. In addition, thanks to its hydrophilic NCC sections, it acts as a one-way valve by preventing the passage of the liquid coming to the filter. In this way, vacuum suction is stopped and overflow and backflow are prevented.

[0044] In the studies carried out within the scope of the invention, PE / NCC composite filters were produced by hot pressing using the sintering technique as seen in Figure 2. It is difficult to give a homogeneous mixture due to the structure of two hydrophilic and hydrophobic materials. Generally, the mixture is more suitable for giving a heterogeneous structure that will give phase separation and the fact that both are white in color prevents the phase difference from being visible to the eye. Phase separation can be understood by performing surface characterization (SEM and contact angle measurement) after obtaining the filter. The weight of the equivalent filter was determined and more than one sample was prepared by changing the NCC amounts in the total weight. An alcohol solvent, preferably ethanol, was added to the mixture of NCC and PE (Mw= 125,000 g / mol) in predetermined amounts for the composite (1 , 10, 20, 30 and 50% NCC by weight according to the PE amount) and stirred at room conditions until the solvent completely evaporated. For further drying of the mixture, it was left in the oven at 50eC for 24 hours and then mixed in a ball mill for different periods and rotation speeds. These mixtures were placed in metal molds prepared according to the dimensions of the equivalent filter and hot press was applied for 5-30 minutes at different temperatures (120-180°C) and pressures (0.5-1 psi). The metal mold to be used in filter production was designed by calculating it according to the standard dimensions of the suction bag filter in the Solidworks program. After the mold material for this designed mold was provided, it was processed on a computer-aided numerical control (CNC) bench. White composite filters with the desired pore size and mold shape were produced with the sintering method thanks to the hot press.

[0045] Whether the obtained composite filter has the desired properties to be used in the suction bag was characterized by comparing it with its equivalent as a result of the analyzes. Figure 3 shows the SEM image of the inventive filter obtained by sintering at 130 O temperature and 0.5 psi pressure with a PE:NCC composition ratio of 95:5 by weight, and it was observed that pores were formed. In addition, the composite filter was immersed in water and as a result of the SEM images taken, it was seen that there was swelling in the places where it came into contact with water due to the presence of NCC, and therefore the pores closed. The PE / NCC composite filter prepared in a laboratory environment gave positive results in a certain vacuum range when used for application with its porous structure. When tested in both laboratory and hospital environments, it was seen that the pores in the filter closed in the presence of NCC when in contact with liquid, preventing liquid leakage into the vacuum. In the studies conducted within the scope of the invention, it was observed that similar positive results could be obtained within the compositions given in Table 1.

[0046] For a high-performance product, it is important to mix the components homogeneously. Since they are prone to phase separation, maleic anhydride-derived compatibilizers can also be used in the mixture or product quality can be increased by blending them homogeneously in mechanical mills such as ball mills.

[0047] With its single-body design that meets the needs of high volume, single-press assembly, the tendency of PE polymer to sinter and obtain a porous structure is higher in hydrophobic suction filters compared to other polymer types, and the fact that it has a faster closing feature in contact with the liquid by adding hydrophilic cellulose to this structure offers advantages in the use of the invention. The hydrophobic filter self-closing design achieved during the invention prevents infectious fluid from entering hospital central vacuum lines. The optimized designs have high airflow and high bacterial filtration efficiency (BFE), thus preventing infections. They have significant industrial benefits such as being designed as a single component for easier, push-in assembly, eliminating the cost and complexity of multi-piece mechanical valves.

Claims

CLAIMS1. A hydrophobic filter production method that will prevent contamination by not allowing the passage of microorganisms to be used in the covers of suction bags and that will stop the suction and prevent overflow and backflow by acting as a check-valve when the bag is full, characterized by comprising; the following process steps: i. mixing predetermined amounts of nanocrystalline cellulose and polyethylene in a solvent, ii. removing the solvent and drying the mixture, iii. grinding the dried nanocrystalline cellulose and polyethylene mixture to obtain a homogeneous powder mixture, iv. placing the homogeneous powder mixture in a mold in the desired filter shape and pressing it under a temperature and pressure close to the melting temperature, v. removing the obtained hydrophobic filter from the mold.

2. The production method according to claim 1 , characterized in that; (i) 1-50% nanocrystalline cellulose and 50-99% polyethylene are used by weight in the process step.

3. The production method according to claim 1 , characterized in that; 1 -10% nanocrystalline cellulose and 90-99% polyethylene by weight are used in the process step (i).

4. The production method according to claim 1 , characterized in that; in the process step (i) nanocrystalline cellulose and polyethylene are added to an alcohol solvent and mixed until the solvent completely evaporates at room conditions.

5. The production method according to claim 1 , characterized in that; drying at 50eC in the process step (ii).

6. The production method according to claim 1 , characterized in that; drying for 24 hours in the process step (ii).

7. The production method according to claim 1 , characterized in that; mixing in a ball mill to prevent phase separation in the process step (iii).

8. The production method according to claim 1 , characterized in that; maleic anhydride derivative compatibilizers are used in mixing to prevent phase separation in the process step (iii).

9. The production method according to claim 1 , characterized in that; pressing at 120- 180°C in the process step (iv).

10. The production method according to claim 1 , characterized in that pressing at 130- 150°C in the process step (iv).

11. The production method according to claim 1 , characterized in that; pressing for 5-30 minutes in the process step (iv).

12. The production method according to claim 1 , characterized in that; pressing at 0.5-1 psi pressure in the process step (iv).

13. The production method according to claim 1 , characterized in that; Low density polyethylene (LDPE), High Density Polyethylene (HDPE), Ultra high molecular weight polyethylene (UHMWPE) is used in the process step (i).

14. The production method according to claim 1 , characterized in that; Nano crystalline cellulose containing cellulose crystals with a diameter of 5 to 500nm is used in the process step (i).

15. A hydrophobic filter with a polyethylene nanocrystalline cellulose composite structure comprising pores with dimensions below 0.2pm, obtained according to any of the above claims.

16. A suction bag comprising the hydrophobic filter according to claim 15.

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