Polytetrafluoroethylene lining pipe

Abstract

The invention relates to a medical catheter material, and discloses a polytetrafluoroethylene lining tube, the wall thickness of the polytetrafluoroethylene lining tube is 0.01-0.03 mm, in a mechanical property test experiment, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lining tube is greater than 0.6, and in a flexibility test process, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lining tube is greater than 0.6. When the pressure of the head end of the polytetrafluoroethylene lining pipe is 5N, the maximum bending position is bent by at least 1mm, and the excellent mechanical property ensures the stability and the reliability of the conduit when a passage is maintained.

Description

Technical Field

[0001] The invention relates to medical catheter materials, in particular to a polytetrafluoroethylene lined tube. Background Art

[0002] Intravascular surgery, which involves inserting a catheter into a blood vessel to remove and treat a diseased area inside the blood vessel, is becoming more and more popular because it is less burdensome to the patient. The catheters used in these surgeries are usually coated or lined on the inner wall to provide a smooth inner surface.

[0003] The mechanical properties of the catheter lining are extremely important. For example, when certain devices (e.g., shunts, embolization, aneurysm bridging, stents, and thrombectomy devices) are passed through the catheter in a compressed state, the catheter may require a high yield strength. On the other hand, when the catheter must pass through a vascular system involving sharp twists and turns (e.g., cerebrovascular system and below-the-knee applications), the tip of the catheter lining needs to have a high degree of flexibility so that the tip of the catheter can be bent into the curved vessel.

[0004] PTFE tubes are used in medical catheters as catheter linings due to their excellent properties such as chemical resistance, non-adhesiveness, and low friction. However, although some existing extrusion processes can produce PTFE tubes with thin walls and high yield strength, it is difficult to ensure that the front end of the PTFE tube has sufficient flexibility, and it is difficult for it to enter curved vessels when traveling in the blood vessels, affecting the smooth progress of the operation. Summary of the invention

[0005] Therefore, it is necessary to provide a polytetrafluoroethylene lined tube to solve the problem that the existing PTFE tube cannot take into account both the yield strength and the softness of the head end when the PTFE thin-walled tube is extruded.

[0006] To achieve the above-mentioned purpose, the present invention provides a polytetrafluoroethylene lined tube, the wall thickness of the polytetrafluoroethylene lined tube is 0.01-0.03mm, in the mechanical property test experiment, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lined tube is greater than 0.6, and in the softness test process, when the pressure of the head end of the polytetrafluoroethylene lined tube is 5N, the maximum bending point bends at least 1mm.

[0007] Furthermore, when measuring the softness, the distance between the maximum bending point of the polytetrafluoroethylene lined tube and the head end does not exceed 5 mm.

[0008] Furthermore, in a mechanical property test experiment, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lined tube is greater than 0.7.

[0009] A medical catheter comprises the polytetrafluoroethylene liner tube.

[0010] Furthermore, the medical catheter is an interventional medical catheter.

[0011] The above technical solution has the following beneficial effects:

[0012] The polytetrafluoroethylene liner tube of the present invention can be particularly used for interventional medical catheters. The ratio of the yield strength to the tensile strength of the polytetrafluoroethylene liner tube is greater than 0.7. The excellent mechanical properties ensure the stability and reliability of the catheter when maintaining the passage. The higher yield strength means that the material can withstand greater stress without plastic failure. At the same time, the better softness of the head end facilitates the turning of the medical catheter in the blood vessel and avoids collision damage to the blood vessel. At the same time, it can make it easy for the catheter to enter the complex and curved blood vessels, which is conducive to the smooth progress of the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the softness test of the polytetrafluoroethylene tube. DETAILED DESCRIPTION

[0014] In an embodiment of the present invention, a polytetrafluoroethylene lined tube is disclosed, wherein the wall thickness of the polytetrafluoroethylene lined tube is 0.01-0.03 mm, and in a mechanical property test experiment, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lined tube is greater than 0.6, and during a softness test, when the pressure at the head end of the polytetrafluoroethylene lined tube is 5N, the maximum bend is at least 1 mm.

[0015] In some embodiments, the polytetrafluoroethylene lined tube has a wall thickness of 0.01-0.03 mm, and specifically the thickness of the polytetrafluoroethylene lined tube may be 0.01-0.02 mm or 0.02-0.03 mm.

[0016] In some embodiments, in a mechanical property test experiment, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lined tube is greater than 0.7.

[0017] Specifically, in the force-tensile curve test of the polytetrafluoroethylene tube, the tensile strength is 85-90MPa, 90-95MPa, 95-100MPa or above 100MPa, and the yield strength is 70-75MPa, 75-80MPa, 80-85MPa or above 85. The high yield strength ensures the reliability of the polytetrafluoroethylene tube during use and ensures that the polytetrafluoroethylene lined tube is not prone to plastic deformation during implantation / intervention. Compared with the prior art tube, the higher ratio of yield strength to tensile strength results in a polytetrafluoroethylene tube with excellent mechanical properties.

[0018] In some embodiments, during a softness test of the polytetrafluoroethylene lined tube of the present invention, the head end of the polytetrafluoroethylene lined tube is bent at a maximum bending point of 1mm-2mm, 2mm-3mm, 3mm-4mm, or 4mm-5mm at a pressure of 5N.

[0019] In the present invention, it can be considered that in the softness test experiment, when the pressure at the head end of the polytetrafluoroethylene tube is 5N, the greater the bending strength of the polytetrafluoroethylene tube, the softer the head end of the polytetrafluoroethylene tube. Therefore, during the catheter intervention / implantation process, the head end of the catheter can be well bent to avoid damage to human tissue, and at the same time, it is convenient to turn the catheter head end during the operation.

[0020] In some embodiments, during the softness test of the polytetrafluoroethylene tube of the present invention, the distance between the maximum bend of the polytetrafluoroethylene inner liner tube and the head end does not exceed 5 mm. Specifically, the distance between the maximum bend of the polytetrafluoroethylene inner liner tube and the head end is 1 mm-2 mm, 2 mm-3 mm, 3 mm-4 mm, or 4 mm-5 mm.

[0021] In the present invention, during the softness test, it is generally believed that the closer the maximum bending point of the polytetrafluoroethylene is to the head end, the better the bending and turning performance of the polytetrafluoroethylene tube is, which facilitates the application of the polytetrafluoroethylene tube in medical surgery.

[0022] In the present invention, the preparation method of the polytetrafluoroethylene lined tube comprises: 1. forming a preliminary formed body; 2. extrusion forming; 3. drying process; 4. tube sintering.

[0023] Forming of the preliminary molded body: PTFE and lubricant (isoparaffin solvent oil) are mixed using a roller or the like. The lubricant is used to stay between PTFE particles, which can improve the lubricity between PTFE particles and between PTFE particles and the inner wall of the mold, and inhibit the rapid fibrillation of PTFE particles. Thus, the increase in extrusion pressure is inhibited.

[0024] 2. Extrusion molding: Place the prepared molded body in the extruder, pass it through the die, and form it into a tubular shape. The wall thickness of the tube of the embodiment of the present invention is 0.01-0.03mm. In the present invention, during extrusion, a higher extrusion pressure (above 30MPa) and a lower extrusion speed (below 5mm / min) are maintained, and at the same time, the extrusion die is kept at a lower temperature (≤30°C) during extrusion. Therefore, during the extrusion process, due to the directional arrangement of the molecular chains, the PTFE liner tube produced by the extrusion process of the present invention has a higher yield strength and a higher yield strength and tensile strength ratio, so that the polytetrafluoroethylene liner tube has excellent mechanical properties, and the head end of the liner tube after the extrusion process technology of the present invention has a higher softness, which means that in medical device applications, especially when the catheter needs to withstand greater forces or navigate in complex paths, choosing the PTFE liner tube of the present invention will have higher performance advantages.

[0025] 3. Drying process: The PTFE formed into a tube shape is heated to a temperature below the melting point of PTFE (80-250°C) to fully volatilize the lubricant.

[0026] 4. Tube sintering: The dried PTFE tube is heated to a temperature above the melting point of PTFE and sintered. The tube is usually heated to about 400°C. By heating the tube at a temperature above the melting point, the PTFE particles are fused to each other.

[0027] Product performance test:

[0028] 1. Mechanical properties test

[0029] The prepared polytetrafluoroethylene tube is subjected to a force-tensile performance test, and the yield strength and tensile strength of the polytetrafluoroethylene tube are determined through a force-tensile curve, and the ratio of the yield strength to the tensile strength is recorded as P.

[0030] 2. Softness test

[0031] The testing process of PTFE tube is as follows: Figure 1 As shown, the polytetrafluoroethylene tube is clamped vertically, and the clamping position is 10 mm away from the head end of the polytetrafluoroethylene tube. The head end of the polytetrafluoroethylene tube is pressed vertically down to the pressure sensor. When the pressure at the head end reaches 5N, record it. The bending amount at the maximum bending point of the polytetrafluoroethylene tube is recorded as D and the distance between the maximum bending point and the head end is recorded as L.

[0032] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments and accompanying drawings.

[0033] Example 1

[0034] 100 parts of PTFE fine powder and 25 parts of lubricant are mixed and sieved, and the mixed material is put into a preformer to prepare a preform, and an extruder is used for extrusion molding. The preform is put into an extrusion molding machine, extruded at an extrusion pressure of 30-40MPa, and a punching speed of 2-3mm / min is maintained, and formed into a tube shape. The extruder mold temperature is controlled at ≤30°C. The formed pipe passes through an oven (including two drying furnaces with temperatures of 120°C and 200°C in sequence) and a sintering furnace (a sintering furnace with a temperature of 410°C), and the lubricant is dried in the oven. The dried pipe is heated and sintered in the sintering furnace, and the PTFE particles are melted and adhered to each other, and then cooled to obtain a product pipe. The inner diameter of the product pipe is 0.533mm, the outer diameter is 0.583mm, and the wall thickness is 0.025mm. The obtained pipe is subjected to force tensile curve and softness test. The results are shown in Table 1.

[0035] Example 2

[0036] 100 parts of PTFE fine powder and 22 parts of lubricant are mixed and sieved, and the mixed material is put into a preformer to prepare a preform, and an extruder is used for extrusion molding. The preform is put into an extrusion molding machine, extruded at an extrusion pressure of 30-40MPa, and a punching speed of 2-3mm / min is maintained, and formed into a tube shape. The extruder mold temperature is controlled at ≤30°C. The formed pipe passes through an oven (including two drying furnaces with temperatures of 120°C and 200°C in sequence) and a sintering furnace (a sintering furnace with a temperature of 410°C), and the lubricant is dried in the oven. The dried pipe is heated and sintered in the sintering furnace, and the PTFE particles are melted and adhered to each other, and then cooled to obtain a product pipe. The inner diameter of the product pipe is 0.526mm, the outer diameter is 0.586mm, and the wall thickness is 0.030mm. The obtained pipe is subjected to force tensile curve and softness test. The results are shown in Table 1.

[0037] Example 3

[0038] 100 parts of PTFE fine powder and 30 parts of lubricant are mixed and sieved, and the mixed material is put into a preformer to prepare a preform, and an extruder is used for extrusion molding. The preform is put into an extrusion molding machine, extruded at an extrusion pressure of 30-40MPa, and a punching speed of 2-3mm / min is maintained, and formed into a tube shape. The extruder mold temperature is controlled at ≤30°C. The formed pipe passes through an oven (including two drying furnaces with temperatures of 120°C and 200°C in sequence) and a sintering furnace (a sintering furnace with a temperature of 410°C), and the lubricant is dried in the oven. The dried pipe is heated and sintered in the sintering furnace, and the PTFE particles are melted and adhered to each other, and then cooled to obtain a product pipe. The inner diameter of the product pipe is 0.489mm, the outer diameter is 0.533mm, and the wall thickness is 0.022mm. The obtained pipe is subjected to force tensile curve and softness test. The results are shown in Table 1.

[0039] Competitive polytetrafluoroethylene tubes on the market were selected for force-tensile curve and softness tests.

[0040] Table 1. Yield strength and tensile strength ratio P and softness test results of polytetrafluoroethylene tubes.

[0041]

[0042]

[0043] The polytetrafluoroethylene liner tube of the present invention can be particularly used for interventional medical catheters. The high yield strength and tensile strength ratio ensures that the catheter maintains its passage and avoids being flattened, effectively balancing the mechanical properties of the polytetrafluoroethylene tube. At the same time, the good softness of the head end facilitates the turning of the medical catheter in the blood vessel and avoids collision damage with the vascular tissue.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "include..." or "comprise..." do not exclude the existence of other elements in the process, method, article or terminal device including the elements. In addition, in this article, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself.

[0045] Although the above embodiments have been described, once those skilled in the art know the basic creative concepts, they can make additional changes and modifications to these embodiments. Therefore, the above description is only an embodiment of the present invention and does not limit the patent protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A polytetrafluoroethylene lined pipe, characterized in that: The wall thickness of the polytetrafluoroethylene lined tube is 0.01-0.03mm. In the mechanical property test experiment, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lined tube is greater than 0.

6. During the softness test, when the pressure of the polytetrafluoroethylene lined tube head end is 5N, the maximum bending point bends at least 1mm.

2. The polytetrafluoroethylene lined pipe according to claim 1, characterized in that: When measuring the softness, the distance between the maximum bending point of the polytetrafluoroethylene lined tube and the head end does not exceed 5 mm.

3. The polytetrafluoroethylene lined pipe according to claim 1, characterized in that: In a mechanical property test experiment, the ratio of the yield strength to the tensile strength of the polytetrafluoroethylene lined tube is greater than 0.

7.

4. A medical catheter, characterized in that: A polytetrafluoroethylene lined tube comprising any one of claims 1 to 3.

5. The medical catheter according to claim 4, characterized in that The medical catheter is an interventional medical catheter.

Images