Processing method of expanded PTFE (Polytetrafluoroethylene) for medical treatment

Abstract

The invention discloses a medical expanded PTFE processing method which comprises the following steps: S1, raw material treatment; s2, primary extrusion; s3, carrying out secondary extrusion; s4, heating and deoiling; s5, segmental calcining and drafting: continuously feeding the oil-removed linear material into a calcining station, calcining to a molten state, and dividing into two stages: stage I (heating and calcining): feeding the linear material into a first heating device, arranging a groove body in the first heating device, enabling the linear material to pass through the groove body, supporting and protecting the material by the groove body, and feeding the linear material into a second heating device; deformation or deviation of the material during high-temperature calcination is avoided; and a second stage (heating drafting): the linear material treated in the first stage enters a second heating device, a supporting plate with radian is arranged in the second heating device, and the linear material is attached to the surface of the supporting plate and passes through the second heating device. The problems that according to an existing processing method, mixing is uneven, the line breaking rate is high, additive recycling is poor, and the biocompatibility of a finished product is difficult to guarantee are solved.

Description

Technical Field

[0001] This invention relates to the field of PTFE processing technology, and more specifically to a method for processing expanded PTFE for medical use. Background Technology

[0002] Expanded PTFE materials are widely used in medical surgical sutures due to their excellent biocompatibility, corrosion resistance, and structural stability. However, existing processing methods for expanded PTFE used in medical applications have significant shortcomings: First, the integration of raw material mixing and extrusion processes is often poor, resulting in uneven mixing of powdered PTFE and additives, leading to inconsistent material density in subsequent molding and affecting the mechanical properties of the surgical sutures. Second, suture breakage is common during processing, especially during the heating and stretching stage, where the lack of an effective protective structure makes the sutures prone to breakage at high temperatures, reducing production efficiency. Third, the low recycling rate of additives (such as white oil) not only increases production costs but may also cause environmental pollution. Furthermore, some processing methods have poorly designed temperature, speed, and other parameters, resulting in substandard biocompatibility of the finished product, making it difficult to meet the stringent requirements of "high safety, low breakage rate, and stable performance" for medical surgical sutures. Summary of the Invention

[0003] This invention provides a processing method for expanded PTFE for medical use, which solves the problems of uneven mixing, high wire breakage rate, poor additive recovery, and difficulty in ensuring the biocompatibility of the finished product in existing processing methods.

[0004] To address the aforementioned technical problems, this invention provides a method for processing expanded PTFE for medical applications, comprising the following steps: S1. Raw material processing: Mix the initial powdered PTFE material with light white oil; S2, single extrusion: The mixture after S1 is fed into the extrusion equipment, and the pressure of the extrusion equipment is used to densify the mixture to obtain block material. S3. Secondary extrusion: The block material obtained in step S2 is fed into a secondary extrusion device and extruded into a continuous linear material. At the same time, the linear material is wound and packaged into a tray in an orderly manner through a tray loading device to facilitate subsequent processing. S4. Heating and degreasing: The linear material obtained in step S3 is fed into a heating and degreasing device to remove the light white oil from the linear material at high temperature; the removed white oil is collected by a recovery device and reused for the raw material processing in step S1 to achieve recycling. S5. Segmented Melting and Drawing: The oil-free linear material continues to the calcination station and is heated to a high-elasticity state, which is divided into two stages: Phase 1, heating and calcination: The linear material is fed into the first heating device, which is equipped with a trough. The linear material passes through the trough, and the trough isolates, supports and protects the material to prevent it from becoming entangled or shifting during high-temperature melting. Phase Two, Heating and Stretching: The linear material processed in Phase One enters the second heating device, which is equipped with an arc-shaped metal support plate. The linear material passes through the support plate while adhering to its surface. The support plate prevents the linear material from breaking during high-temperature stretching, ensuring that no damage occurs during subsequent stretching. The final product is an expanded PTFE wire that can be used as a medical surgical suture.

[0005] Furthermore, the processing parameters in step S4 are: degreasing: 120-180℃, speed: 5-10 meters / minute.

[0006] Furthermore, the processing parameters in step S5 are: calcination: 180-260℃, speed: 5-12 m / min; drawing: 200-320℃, speed: 90-120 m / min.

[0007] The beneficial effects of this invention are as follows: 1. The raw materials are mixed evenly, ensuring the performance of the finished product: In step S1, the light white oil and powdered PTFE are fully mixed, so that the white oil evenly coats the powder particles, providing a good foundation for subsequent extrusion molding; the two extrusion processes gradually realize the densification and molding of the material, ensuring the uniform density of the linear material, which ensures the mechanical properties (such as tensile strength) of the finished surgical suture, and avoids performance defects caused by uneven mixing.

[0008] 2. Segmented protection design to reduce wire breakage rate: The calcination and stretching stage adopts segmented processing and is equipped with a special protective structure: the tank in stage one can limit the displacement and deformation of the linear material, and the curved support plate in stage two can disperse the force on the material, avoiding the material from breaking due to embrittlement or stress concentration at high temperature; combined with precise temperature and speed parameter control, the wire breakage rate during processing is greatly reduced, and production efficiency is improved.

[0009] 3. Recycling of white oil, reducing costs and protecting the environment: In step S4, light white oil is recovered by heating and degreasing. The recovered white oil can be reused for raw material processing, realizing the recycling of additives. This not only reduces raw material waste and production costs, but also reduces waste emissions, meeting environmental protection production requirements.

[0010] 4. Precise parameter matching to ensure biocompatibility: The processing parameters are designed specifically for medical applications. The temperature and speed parameters of heating degreasing and calcination stretching are optimized and matched to ensure the removal of residual impurities while avoiding the impact of high temperature on the biocompatibility of PTFE materials. The finished expanded PTFE wire has excellent biocompatibility, meets the safety standards for use in medical surgical sutures, and is suitable for the internal surgical environment of the human body. Detailed Implementation

[0011] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0012] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0013] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0014] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0015] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0016] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0017] This invention provides a method for processing expanded PTFE for medical use, the specific implementation process of which is as follows: 1.1 Raw material preparation and processing (S1) Select powdered PTFE material that meets medical-grade standards to ensure high purity and no impurities; add light white oil to the powdered PTFE material according to the preset ratio, and stir thoroughly in a mixing device to ensure that the light white oil evenly coats each PTFE powder particle, forming a uniform mixture and avoiding local clumping or uneven distribution of white oil.

[0018] 1.2 One-time extrusion into blocks (S2) The uniformly mixed material in step S1 is fed into a hydraulic extrusion device. The piston thrust of the extrusion device densifies the mixture in the mold, forming a compact, non-porous block material. After extrusion, the block material is removed from the mold and the surface is inspected for defects such as cracks and bubbles. Defective products need to be crushed again and returned to step S1 for reprocessing.

[0019] 1.3 Secondary extrusion into a production line (S3) The qualified block material is fed into the secondary extrusion equipment, which is equipped with a linear forming die. The die aperture is adjusted according to the diameter of the target surgical suture. After being extruded by the die, the block material is formed into a continuous linear material. At the same time, the loading equipment is started to wind the linear material into the take-up reel in an orderly manner, ensuring that the suture is free from tangling and stretching deformation.

[0020] 1.4 Heating for oil removal and recovery (S4) The linear material on the take-up reel is placed into a continuous heating degreasing device. The device uses electric heating and is set to a degreasing temperature of 120-180℃ and a processing speed of 5-10 meters per minute. The high temperature causes the light white oil in the linear material to evaporate. The evaporated white oil vapor is cooled and liquefied by a condensation and recovery device inside the device, collected and stored in a special container. The purity of the recovered white oil is tested regularly to ensure that there are no impurities before it is reused for raw material processing in step S1, thus achieving recycling.

[0021] 1.5-segment calcination and stretching (S5) 1.5.1 Stage One (Heating and Calcination) The degreased linear material is introduced into the first heating device. The tank inside the device is made of high-temperature resistant and non-stick material. The linear material passes through the middle of the tank, and the limiting structure on both sides of the tank prevents the material from shifting. The calcination temperature is set to 180-260℃ and the processing speed is 5-12 meters / minute. The linear material is melted by the high temperature, removing residual trace impurities and optimizing the internal structure of the material.

[0022] 1.5.2 Stage Two (Heating and Stretching) After calcination, the linear material is directly fed into the second heating device. The curved support plate inside the device is in contact with the linear material, and the curvature of the support plate is designed according to the material diameter (to ensure uniform stress on the material) to prevent material breakage at high temperatures. The drawing temperature is set at 200-320℃ and the drawing speed at 90-120 m / min. The linear material is stretched to the target diameter by the tension of the drawing equipment to form a finished expanded PTFE wire with uniform structure and stable performance. After cooling, the finished product is cut and inspected, and qualified products are packaged and stored.

[0023] 2. Verification of finished product characteristics 2.1 The expanded PTFE wire prepared by this method is used in medical surgical sutures and has the following characteristics after testing: 2.1.1 Biocompatibility: Meets medical biocompatibility standards and has no sensitizing or toxic reactions after implantation in the human body.

[0024] 2.1.2 Mechanical properties: High tensile strength, meeting the suture stretching requirements of surgical sutures.

[0025] 2.1.3 Processing stability: The breakage rate is low throughout the entire processing.

[0026] 2.1.4 Environmental friendliness: Light white oil has a high recycling rate, which greatly reduces resource waste and environmental pollution.

[0027] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A process for the production of an expanded PTFE for medical use, characterized in that, It comprises the following steps: S1, raw material processing: add light white oil to the initial powdered PTFE material; S2, primary extrusion: send the mixture after S1 processing into the extrusion equipment, and make the mixture densified through the pressure of the extrusion equipment to obtain blocky material; S3, secondary extrusion: send the blocky material obtained in step S2 into the secondary extrusion equipment, and extrude into continuous linear material, and simultaneously, through the tray equipment, the linear material is orderly wound and placed in the tray, which is convenient for subsequent processing; S4, heating and deoiling: send the linear material obtained in step S3 into the heating and deoiling equipment, and remove the light white oil in the linear material through high temperature; the removed white oil is collected by the recovery device and then reused in the raw material processing of step S1, realizing recycling; S5, section melting and drawing: the deoiled linear material continues to enter the calcination station, and is burned to high elastic state in two stages: Stage one, heating and calcination: send the linear material into the first heating device, which is provided with a groove, and the linear material passes through the groove, and the groove plays the role of isolation, support and protection for the material, avoiding entanglement and deviation of the material in high temperature melting and calcination; Stage two, heating and drawing: the linear material after stage one processing enters the second heating device, which is provided with a metal support plate with an arc, and the linear material passes through the surface of the support plate, and the support plate can prevent the linear material from breaking in high temperature drawing, and ensure that there is no damage in the subsequent stretching process, and finally obtain the expanded PTFE linear material product which can be used for medical operation line.

2. The process for processing expanded PTFE for medical treatment according to claim 1, characterized by, The processing parameters in step S4 are: deoiling: 120-180℃, speed: 5-10m / min.

3. The process for manufacturing an expanded PTFE for medical treatment according to claim 1, wherein The processing parameters in step S5 are: calcination: 180-260℃, speed: 5-12m / min, drawing: 200-320℃, speed: 90-120m / min.