A ready-to-wear expanded polytetrafluoroethylene artificial blood vessel and its preparation method

Abstract

The present scheme provides a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel and a preparation method thereof, comprising the following steps: mixing a PTFE dispersion resin with a first compression ratio and a lubricating oil, and maturing to obtain a first PTFE mixture; mixing a PTFE dispersion resin with a second compression ratio and a lubricating oil, and maturing to obtain a second PTFE mixture, wherein the first compression ratio is higher than the second compression ratio; pre-pressing the first PTFE mixture into an intermediate layer cylinder; pre-pressing the second PTFE mixture into an inner layer cylinder and an outer layer cylinder; placing the intermediate layer cylinder into the outer layer cylinder, placing the inner layer cylinder into the intermediate layer cylinder to obtain a composite cylinder, and subjecting the composite cylinder to a compacting process to obtain a secondary compacting cylinder; and subjecting the secondary compacting cylinder to uniaxial stretching to obtain a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel that is not delaminated after puncture.

Description

Technical Field

[0001] The invention relates to the field of implantable medical devices, and in particular to a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel and a preparation method thereof. Background Art

[0002] Expanded polytetrafluoroethylene (PTFE) is a polymer material obtained by special processing of polytetrafluoroethylene (PTFE). It has good biocompatibility, anticoagulation and strong inertness. The expanded PTFE artificial blood vessels prepared from it have the advantages of good biocompatibility and anticoagulation, porosity, softness, easy suturing and easy puncture.

[0003] At present, PTFE artificial blood vessels are mainly prepared by uniaxial stretching method, and the specific process is as follows: PTFE dispersed resin and lubricant are mixed - matured - pressed - extruded - degreased - stretched - heat set - product. The blood vessels obtained by this preparation have a single structure. In order to prevent bleeding, patients cannot puncture the implanted artificial blood vessels in time after implantation. They need to wait until the inner wall of the artificial blood vessel is endothelialized before puncturing and use, which takes a long time and is very inconvenient for patients. Gore Company of the United States has developed a ready-to-puncture artificial blood vessel with a silicone layer in the middle and expanded polytetrafluoroethylene layers on both sides. After implantation in the human body, it can be directly punctured (US2006 / 0118236A1), but it is found that the inner polytetrafluoroethylene layer and the silicone layer are very easy to delaminate during puncture (the bonding strength between polytetrafluoroethylene and silicone is poor), and when the artificial blood vessel is trimmed to match the autologous blood vessel, it is necessary to avoid the middle silicone layer from being exposed and contacting with blood to form acute thrombosis, which increases the difficulty in clinical use.

[0004] JP2970320B2 puts together multiple uniaxially stretched PTFE tube membranes, and directly bonds the layers by heating to prepare a PTFE artificial blood vessel with a multilayer structure. This preparation method has low interlayer strength and is easy to delaminate during puncture. JPH10505266A discloses the technical content of compressing the extrudate between two dies to produce an asymmetric extrudate. The prepared tube has a large diameter at one end and a small diameter at another end in the axial direction. This prepared blood vessel cannot meet the requirements of ready-to-wear blood vessels. Summary of the invention

[0005] The object of the present invention is to provide a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel and a preparation method thereof. PTFE resins with different compression ratios are first subjected to pre-pressing treatment, and the high-compression ratio blank is used as the middle layer, and the low-compression ratio blank is used as the inner layer and the outer layer. Then, a secondary pressing treatment is performed to form an integrated blank, and the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel can be obtained after uniaxial stretching.

[0006] To achieve the above objectives, the present technical solution provides a method for preparing a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel, comprising the following steps:

[0007] (1) mixing a PTFE dispersion resin having a first compression ratio and a lubricating oil, and aging the mixture to obtain a first PTFE mixture;

[0008] (2) mixing and aging a PTFE dispersion resin with a second compression ratio and a lubricating oil to obtain a second PTFE mixture, wherein the first compression ratio is higher than the second compression ratio;

[0009] (3) pre-pressing the first PTFE mixture into an intermediate layer cylinder;

[0010] (4) pre-pressing the second PTFE mixture into an inner cylinder and an outer cylinder;

[0011] (5) placing the middle cylinder into the outer cylinder, and placing the inner cylinder into the middle cylinder to obtain a composite cylinder, wherein the outer cylinder, the middle cylinder, and the inner cylinder have the same length;

[0012] (6) performing a green compacting process on the composite cylinder to obtain a secondary green compacting cylinder;

[0013] (7) The secondary pressed cylinder is subjected to uniaxial stretching to obtain a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel.

[0014] The ready-to-wear expanded polytetrafluoroethylene artificial blood vessel prepared in this scheme has a three-layer structure and an asymmetric structure along the tube wall. The outer layer and the inner layer of the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel are both channels composed of "fiber-node-fiber", and the middle layer is a dense layer, which provides the blood vessel with higher hardness and radial elasticity. The puncture hole can heal automatically to prevent blood leakage and shorten the hemostasis time.

[0015] In addition, the raw materials of the three-layer structure of the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel of this scheme are all PTFE resin, and the three-layer structure is pre-pressed and twice pressed to achieve a tight combination effect, so that the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel obtained by this scheme avoids the stratification phenomenon caused by material compatibility issues, and because the middle layer is a dense layer prepared from a high compression ratio PTFE resin, it can play a role in stabilizing the structure during the puncture process, thereby limiting the movement of the inner and outer layers to prevent stratification caused by the puncture force. The outer and inner layers are both pore structures composed of "fiber-node-fiber". This structure can not only provide a good environment for cell growth, adhesion, and migration, but also during puncture, the pore structure can buffer the puncture force to a certain extent, so that the puncture force is evenly distributed on the entire tube wall, rather than concentrated in a certain layer to cause stratification. At the same time, the pore structure of the inner and outer layers also cooperates with the middle dense layer to jointly maintain the overall structural stability of the blood vessel and reduce the possibility of stratification.

[0016] In step (1), the compression ratio of the first compression ratio is greater than 1000. The intermediate layer cylinder prepared by the PTFE dispersion resin of the first compression ratio can make the intermediate layer of the final ready-to-wear expanded polytetrafluoroethylene artificial blood vessel have better density and stability, thereby providing the blood vessel with higher hardness and radial elasticity, which is very important for the blood vessel to withstand blood flow pressure in the body and the healing of the hole after puncture.

[0017] In step (1), the lubricating oil is one or any combination of Isopar G, Isopar L, and Isopar H, the mass ratio of PTFE dispersed resin to lubricating oil is 100:23-100:28, the aging temperature is 30-80° C., and the aging time is 12-24 h.

[0018] In step (2), the compression ratio of the second compression ratio is less than 500. The lower compression ratio enables the PTFE dispersed resin to form a relatively loose structure during the subsequent processing, which is compatible with the pore structure of "fiber-node-fiber" required for the inner and outer layers of the artificial blood vessel. This loose structure is conducive to the growth, adhesion and migration of cells, while the higher porosity also facilitates the exchange of nutrients.

[0019] In step (2), the lubricating oil is one or any combination of Isopar G, Isopar L, and Isopar H, the mass ratio of PTFE dispersed resin to lubricating oil is 100:17-100:22, the aging temperature is 30-80° C., and the aging time is 12-24 h.

[0020] In step (3), the first PTFE mixture is pre-pressed into an intermediate layer cylinder with a pre-pressing pressure of 1.0 to 1.5 T and a holding time of 100 to 180 seconds.

[0021] In step (4), the second PTFE mixture is pre-pressed into an inner cylinder and an outer cylinder with a pre-pressing pressure of 1.0 to 1.5 T and a holding time of 100 to 180 seconds.

[0022] It is particularly noted that the outer diameter of the inner cylinder is smaller than the inner diameter of the middle cylinder, and the inner diameter of the outer cylinder is larger than the outer diameter of the middle cylinder, so that the outer cylinder, the middle cylinder and the inner cylinder can be sequentially stacked to obtain a composite cylinder.

[0023] In addition, the outer diameter of the inner cylinder is 1-2 mm smaller than the inner diameter of the middle cylinder, and the inner diameter of the outer cylinder is 1-2 mm larger than the outer diameter of the middle cylinder. This has the advantage that the composite cylinder can be smoothly sheathed to ensure that each layer of cylinder is tightly combined after sheathing. Preferably, the outer diameter of the inner cylinder is 1 mm smaller than the inner diameter of the middle cylinder, and the inner diameter of the outer cylinder is 1 mm larger than the outer diameter of the middle cylinder.

[0024] In step (3), in some embodiments, the outer diameter of the intermediate layer cylinder is 55-65 mm, and the inner diameter is 30-40 mm.

[0025] In step (4), in some embodiments, the outer diameter of the inner cylinder is 29-39 mm, and the inner diameter is 16-20 mm. In some embodiments, the outer diameter of the outer cylinder is 70-80 mm, and the inner diameter is 56-66 mm.

[0026] In step (5), after the outer cylinder, the middle cylinder and the inner cylinder are cut into equal lengths, the inner cylinder is inserted into the middle cylinder, and the middle cylinder is inserted into the outer cylinder to form a composite cylinder with a three-layer structure.

[0027] In step (5), in some embodiments, the outer diameter of the composite cylinder is 70-80 mm, and the inner diameter is 16-20 mm.

[0028] In step (6), the composite cylinder is subjected to a green compaction process to obtain a secondary green compaction cylinder having a green compaction pressure of 2.5 to 3.0 T and a holding time of 250 to 350 s.

[0029] In step (7), the secondary pressed cylinder is subjected to uniaxial stretching to obtain a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel. The extrusion speed during uniaxial stretching is 0.5-1.0 m / min, the drafting multiple is 4-6 times, the degreasing temperature is 180-220°C, the stretching temperature is 260-300°C, and the shaping temperature is 310-330°C.

[0030] In step (7), the inner diameter of the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel is 3-6 mm, and the wall thickness is 0.3-0.7 mm.

[0031] In the second aspect, the present scheme provides a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel, which is prepared according to the above-mentioned method for preparing a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel, and is an integral blank, wherein the inner and outer walls of the integral blank are channels composed of "fiber-node-fiber", and the middle of the integral blank is a dense layer.

[0032] Compared with the prior art, this technical solution has the following characteristics and beneficial effects:

[0033] This scheme uses a unique method to obtain a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel. The wall direction is an asymmetric structure. The inner and outer walls of the artificial blood vessel are composed of "fiber-node-fiber" channels, which can fully simulate the natural extracellular matrix structure and provide a good environment for cell growth, adhesion, and migration. The high porosity is conducive to the exchange of nutrients. The middle is a dense layer, which provides high hardness and radial elasticity for the blood vessel. The puncture hole can heal automatically to prevent blood leakage and shorten the hemostasis time. This ready-to-wear expanded polytetrafluoroethylene artificial blood vessel not only achieves innovation in technology, but also shows excellent performance advantages in clinical applications, which is of great significance to improving the safety and effectiveness of vascular implantation surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a morphology of the inner wall of the expanded PTFE tube membrane according to Comparative Example 2 of the present scheme.

[0035] Figure 2 This is a morphology diagram of the outer wall of the expanded PTFE tubular membrane of Comparative Example 2 of the present invention.

[0036] Figure 3 This is a cross-sectional morphology diagram of the tube wall of the expanded PTFE tube membrane of Comparative Example 2 of the present scheme.

[0037] Figure 4 This is a picture of the inner wall morphology of the expanded PTFE tubular membrane of Example 3 of the present scheme.

[0038] Figure 5 This is a picture of the outer wall morphology of the expanded PTFE tubular membrane of Example 3 of the present scheme.

[0039] Figure 6 This is a cross-sectional morphology diagram of the tube wall of the expanded PTFE tube membrane of Example 3 of the present scheme.

[0040] Figure 7This is a diagram of the cross section, outer surface and inner surface of the blood vessel sample of comparative example 3 of the present scheme when punctured with a 16G puncture needle.

[0041] Figure 8 This is a diagram of the cross-section of the expanded PTFE tubular membrane 16G model puncture needle during puncture, and the outer surface and inner surface after puncture in Example 3 of the present scheme. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0043] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0044] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0045] Embodiment 1:

[0046] The high compression ratio PTFE dispersion resin and Isopar H were mixed in a mass ratio of 100:23 and aged at 80°C for 12 hours to obtain a mixture A, wherein the high compression ratio PTFE dispersion resin was PTFE (polytetrafluoroethylene) F-201 material (Daikin 201) produced by Daikin Corporation of Japan; the low compression ratio PTFE dispersion resin and Isopar G were mixed in a mass ratio of 100:17 and aged at 80°C for 12 hours to obtain a mixture B, wherein the low compression ratio PTFE dispersion resin was PTFE (polytetrafluoroethylene) F-106 (Daikin 106) produced by Daikin Corporation of Japan; the mixture A was pre-pressed into a cylinder Y1 with an outer diameter of 55 mm and an inner diameter of 30 mm, and the pre-pressing pressure was 1.0T and the holding time was 180s; the mixture B was pre-pressed into a cylinder Y2 with an outer diameter of 29 mm, an inner diameter of 16 mm and an outer diameter of 70 The cylinder Y3 with an outer diameter of 70 mm and an inner diameter of 56 mm was prepared by pre-pressing at a pressure of 1.0 T and a holding time of 180 s. The cylinders Y1, Y2 and Y3 were cut into the same length, and then Y1 was placed inside Y3 and Y2 was placed inside Y1 to obtain a new cylinder Y4 with an outer diameter of 70 mm and an inner diameter of 16 mm. The cylinder Y4 was pressed again at a pressure of 2.5 T and a holding time of 350 s. The secondary pressed blank was subjected to a uniaxial stretching process to obtain sample 1. The extrusion speed during uniaxial stretching was 0.5 m / min, the draw ratio was 4 times, the degreasing temperature was 180 ℃, the stretching temperature was 260 ℃, the shaping temperature was 310 ℃, the inner diameter of the artificial blood vessel was 3.0 mm, and the wall thickness was 0.3 mm. Example

[0047] 1) High compression ratio PTFE dispersion resin and Isopar L were mixed in a mass ratio of 100:28, and aged at 30°C for 24 hours to obtain a mixture A, wherein the high compression ratio PTFE dispersion resin was PTFE (polytetrafluoroethylene) F-208 material (Daikin 208) produced by Daikin Co., Ltd. of Japan;

[0048] 2) Mix low compression ratio PTFE dispersion resin and Isopar G in a mass ratio of 100:22, and age at 30°C for 24 hours to obtain mixture B, wherein the low compression ratio PTFE dispersion resin is PTFE (polytetrafluoroethylene) F-104 material (Daikin 104) produced by Daikin Corporation of Japan;

[0049] 3) Pre-pressing the mixture A into a cylinder Y1 with an outer diameter of 65 mm and an inner diameter of 40 mm, with a pre-pressing pressure of 1.5 T and a holding time of 100 s;

[0050] 4) Pre-pressing the mixture B into a cylinder Y2 with an outer diameter of 39 mm and an inner diameter of 20 mm and a cylinder Y3 with an outer diameter of 80 mm and an inner diameter of 66 mm, the pre-pressing pressure is 1.5T and the holding time is 100s;

[0051] 5) Cut the cylinders Y1, Y2 and Y3 into the same length, then put Y1 inside Y3 and Y2 inside Y1 to get a new cylinder Y4 with an outer diameter of 80 mm and an inner diameter of 20 mm;

[0052] 6) The cylinder Y4 is pressed again, the pressing pressure is 3.0T, and the holding time is 250s;

[0053] 7) The blank obtained by the secondary pressing was subjected to a uniaxial stretching process to obtain sample 2. During the uniaxial stretching, the extrusion speed was 1.0 m / min, the drawing ratio was 6 times, the degreasing temperature was 220°C, the stretching temperature was 300°C, the shaping temperature was 330°C, the inner diameter of the artificial blood vessel was 6.0 mm, and the wall thickness was 0.7 mm.

[0054] Embodiment 3:

[0055] 1) High compression ratio PTFE dispersion resin and Isopar H were mixed in a mass ratio of 100:25, and aged at 50°C for 16 hours to obtain a mixture A, wherein the high compression ratio PTFE dispersion resin was PTFE (polytetrafluoroethylene) F-205 material (Daikin 205) produced by Daikin Corporation of Japan;

[0056] 2) mixing a low compression ratio PTFE dispersion resin and lubricating oil Isopar G in a mass ratio of 100:20, and aging at 50° C. for 16 h to obtain a mixture B, wherein the low compression ratio PTFE dispersion resin is Solvay Algoflon DF132F (Solvay 132F);

[0057] 3) Pre-pressing the mixture A into a cylinder Y1 with an outer diameter of 60 mm and an inner diameter of 35 mm, with a pre-pressing pressure of 1.2 T and a holding time of 150 s;

[0058] 4) Pre-pressing the mixture B into a cylinder Y2 with an outer diameter of 34 mm and an inner diameter of 18 mm and a cylinder Y3 with an outer diameter of 75 mm and an inner diameter of 61 mm, with a pre-pressing pressure of 1.2 T and a holding time of 150 s;

[0059] 5) Cut the cylinders Y1, Y2 and Y3 into the same length, then put Y1 inside Y3 and Y2 inside Y1 to get a new cylinder Y4 with an outer diameter of 75 mm and an inner diameter of 18 mm;

[0060] 6) The cylinder Y4 is pressed again, with a pressing pressure of 2.7T and a holding time of 300s;

[0061] 7) The secondary pressed blank was subjected to uniaxial stretching to obtain sample 3. The extrusion speed during uniaxial stretching was 0.8 m / min, the drawing ratio was 5 times, the degreasing temperature was 200 °C, the stretching temperature was 2800 °C, the shaping temperature was 320 °C, the inner diameter of the artificial blood vessel was 5.5 mm, and the wall thickness was 0.5 mm.

[0062] Comparative Example 1:

[0063] 1) High compression ratio PTFE dispersion resin and Isopar H were mixed in a mass ratio of 100:25, and aged at 50°C for 16 hours to obtain a mixture A, wherein the high compression ratio PTFE dispersion resin was PTFE (polytetrafluoroethylene) F-205 material (Daikin 205) produced by Daikin Corporation of Japan;

[0064] 2) Pressing the mixture A into a cylinder with an outer diameter of 75 mm and an inner diameter of 18 mm, the pressing pressure is 2.7T, and the holding time is 300s;

[0065] 3) The blank was subjected to uniaxial stretching to obtain sample 4. During uniaxial stretching, the extrusion speed was 0.8 m / min, the drawing ratio was 5 times, the degreasing temperature was 200 °C, the stretching temperature was 2800 °C, the setting temperature was 320 °C, the inner diameter of the artificial blood vessel was 5.5 mm, and the wall thickness was 0.5 mm.

[0066] Comparative Example 2:

[0067] 1) Low compression ratio PTFE dispersion resin and lubricating oil Isopar G were mixed in a mass ratio of 100:20 and aged at 50°C for 16 hours to obtain mixture B, wherein the low compression ratio PTFE dispersion resin was Solvay Algoflon DF132F (Solvay 132F);

[0068] 2) The mixture B was pressed into a cylinder with an outer diameter of 75 mm and an inner diameter of 18 mm, the pressing pressure was 2.7T, and the holding time was 300s;

[0069] 3) The blank was subjected to uniaxial stretching to obtain sample 5. During uniaxial stretching, the extrusion speed was 0.8 m / min, the drafting ratio was 5 times, the degreasing temperature was 200 °C, the stretching temperature was 2800 °C, the shaping temperature was 320 °C, the inner diameter of the artificial blood vessel was 5.5 mm, and the wall thickness was 0.5 mm.

[0070] Comparative Example 3:

[0071] Commercially available from Gore Company, USA.

[0072] Performance testing

[0073] Radial resilience performance test: A sample of 10 cm in length was cut from the tubular membrane of the above-mentioned embodiment and comparative example, and a 100 g weight was used to press the circumferential surface of one end of the sample for 10 seconds. The compressed length of the sample was the diameter of the weight. The weight was removed and the sample was allowed to recover naturally. The time taken to recover to the original state was recorded.

[0074] Puncture hemostasis performance test:

[0075] The blood vessel sample was replaced with the blood vessel of the Labrador Retriever, and the sample was punctured with a 16G puncture needle. When the needle was pulled out, the needle hole was gently pressed with a finger, and the hemostasis time was observed and recorded.

[0076] Table 1 Results of radial resilience performance test and puncture hemostasis time of polytetrafluoroethylene blood vessel samples

[0077]

[0078] It can be seen from Table 1 that the expanded polytetrafluoroethylene artificial blood vessel obtained by the method of the present invention has good radial resilience and rapid hemostasis performance, and is soft to the touch.

[0079] Figure 1 and Figure 2 The inner and outer wall morphology of the tubular membrane in comparative example 2 of the present invention, under the same stretching multiple, the nodes are larger and the gaps are not developed, Figure 3 This is a cross-sectional morphology of the expanded PTFE tube membrane of Comparative Example 2 of this solution, with an obvious single-layer structure. Figure 4 and Figure 5 The inner and outer wall morphology of the tubular membrane in Example 3 of the present invention is a "fiber-node-fiber" structure, with relatively developed voids, providing a good environment for cell growth, adhesion, and migration, and a high porosity is conducive to the exchange of nutrients; Figure 6 This is a cross-sectional morphology of the tube wall of the tubular membrane in Embodiment 3 of the present invention, showing an obvious three-layer structure, with a relatively dense middle layer, providing a higher hardness and radial elasticity for the blood vessel, and the puncture hole position can heal automatically to prevent blood leakage and shorten the hemostasis time; Figure 7 This is a cross-sectional view of a blood vessel sample of Comparative Example 3 of the present scheme when punctured with a 16G puncture needle, and a view of the outer surface and inner surface after puncture. It can be seen from the figure that the membrane on the inner surface is ruptured and separated from the middle silicone layer, which will cause thrombosis; Figure 8 This is a cross-sectional view of the expanded PTFE tubular membrane 16G model puncture needle during puncture, and a view of the outer surface and inner surface after puncture. It can be seen that the inner surface does not bulge or separate after puncture.

[0080] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A method for preparing a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel, characterized in that: The following steps are involved: (1) mixing a PTFE dispersion resin with a first compression ratio and a lubricating oil, and aging the mixture to obtain a first PTFE mixture, wherein the compression ratio of the first compression ratio is greater than 1000; (2) mixing and aging a PTFE dispersion resin with a second compression ratio and a lubricating oil to obtain a second PTFE mixture, wherein the compression ratio of the second compression ratio is less than 500; (3) pre-pressing the first PTFE mixture into an intermediate layer cylinder; (4) pre-pressing the second PTFE mixture into an inner cylinder and an outer cylinder; (5) placing the middle cylinder into the outer cylinder, and placing the inner cylinder into the middle cylinder to obtain a composite cylinder, wherein the outer cylinder, the middle cylinder, and the inner cylinder have the same length; (6) performing a green compacting process on the composite cylinder to obtain a secondary green compacting cylinder; (7) The secondary pressed cylinder is subjected to uniaxial stretching to obtain a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel, wherein the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel is an integral blank.

2. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: In step (1), the mass ratio of PTFE dispersed resin to lubricating oil is 100:23-100:28, the aging temperature is 30-80°C, and the aging time is 12-24 hours.

3. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: In step (2), the mass ratio of PTFE dispersed resin to lubricating oil is 100:17-100:22, the aging temperature is 30-80°C, and the aging time is 12-24 hours.

4. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: In step (3), the first PTFE mixture is pre-pressed into an intermediate cylinder with a pre-pressing pressure of 1.0 to 1.5 T and a holding time of 100 to 180 seconds. In step (4), the second PTFE mixture is pre-pressed into an inner cylinder and an outer cylinder with a pre-pressing pressure of 1.0 to 1.5 T and a holding time of 100 to 180 seconds.

5. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: The outer diameter of the inner cylinder is 1-2 mm smaller than the inner diameter of the middle cylinder, and the inner diameter of the outer cylinder is 1-2 mm larger than the outer diameter of the middle cylinder.

6. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: The outer diameter of the middle cylinder is 55~65mm, and the inner diameter is 30~40mm; the outer diameter of the inner cylinder is 29~39mm, and the inner diameter is 16~20mm; the outer diameter of the outer cylinder is 70~80mm, and the inner diameter is 56~66mm.

7. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: In step (6), the composite cylinder is subjected to a green compaction process to obtain a secondary green compaction cylinder having a green compaction pressure of 2.5 to 3.0 T and a holding time of 250 to 350 s.

8. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: In step (7), the secondary pressed cylinder is subjected to uniaxial stretching to obtain a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel. The extrusion speed during uniaxial stretching is 0.5-1.0 m / min, the drafting multiple is 4-6 times, the degreasing temperature is 180-220°C, the stretching temperature is 260-300°C, and the shaping temperature is 310-330°C.

9. The method for preparing the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to claim 1, characterized in that: The inner diameter of the ready-to-wear expanded polytetrafluoroethylene artificial blood vessel is 3~6mm and the wall thickness is 0.3~0.7mm.

10. A ready-to-wear expanded polytetrafluoroethylene artificial blood vessel, characterized in that: The method for preparing a ready-to-wear expanded polytetrafluoroethylene artificial blood vessel according to any one of claims 1 to 9 is an integral blank, wherein the inner wall and the outer wall of the integral blank are channels composed of "fiber-node-fiber", and the middle of the integral blank is a dense layer.

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