Preparation method of endothelium of blood vessel

Abstract

The invention provides a preparation method of a vascular endothelium, and belongs to the technical field of medical treatment. The invention relates to a preparation method of a vascular endothelium. The preparation method comprises the following steps: S1, mixing polytetrafluoroethylene powder and a liquid lubricant into paste; s2, extruding the paste into a material bar, and calendering the material bar into a polytetrafluoroethylene strip material; s3, the polytetrafluoroethylene strip is longitudinally stretched and transversely stretched at the preset temperature, a microfiber structure is formed on the surface of the polytetrafluoroethylene strip, a porous network is generated, and the liquid lubricant in the polytetrafluoroethylene strip is completely volatilized at the preset temperature; and S4, curling the sheet stock into a tubular shape, and carrying out heat treatment on the splicing end of the sheet stock so that the splicing end is subjected to hot melting and splicing to form the endothelium of the blood vessel. The method has the advantages that the process for manufacturing the endothelium of the blood vessel is simple, and foreign technologies are broken through.

Description

Technical Field

[0001] The invention belongs to the field of medical technology, and in particular to a method for preparing a vascular sheath tunica intima. Background Art

[0002] The vascular sheath currently widely used in interventional surgery is mainly composed of the endothelium, reinforcement layer and outer sheath. The endothelium part is in direct contact with the blood and is required to have good biocompatibility, anti-thrombosis properties, low friction and high flexibility. Expanded polytetrafluoroethylene (ePTFE) is widely used in this application due to its excellent microporous structure and biological inertness.

[0003] However, the current mainstream process for preparing ePTFE tubular membranes is mainly the "extrusion-sintering-biaxial stretching" path. The core problems are: the extrusion process has extremely high requirements for equipment precision and control parameters; the axial and radial thickness consistency of the produced tubes is poor; the stretching speed and temperature window control requirements are stringent; the internal stress in the tubes is not easy to release, resulting in a low yield; the porosity and membrane thickness cannot be flexibly adjusted, affecting the membrane performance.

[0004] Therefore, a new "belt first, then tube" model is proposed, that is, PTFE is first prepared into a belt-like structure, and then curled and spliced ​​to make the vascular sheath lining, which has important industrial value. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned problems in the existing technology and propose a method for preparing the vascular sheath endothelium, which has the characteristics of simple process for making the vascular sheath endothelium and breaking through foreign technology.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a vascular intimal sheath comprises the following steps: S1. Mixing polytetrafluoroethylene powder and liquid lubricant into a paste; S2, extruding the paste into a material rod, and rolling the material rod into a polytetrafluoroethylene tape; S3, stretching the polytetrafluoroethylene tape longitudinally and transversely at a preset temperature to form a microfiber structure on its surface and generate a porous network, wherein the liquid lubricant inside the tape is completely volatilized at the preset temperature; S4. Curling the sheet into a tube, and heat-treating the spliced ​​ends of the sheet to melt-splice them to form the vascular sheath endothelium.

[0007] In the above-mentioned method for preparing the vascular intima, in step S1, the polytetrafluoroethylene powder and the liquid lubricant are mixed at 23-25° C., and after the mixing is completed, the mixture is placed in an oven at 45-50° C. for 22-25 hours.

[0008] In the above-mentioned method for preparing the vascular intima, in step S1, the mixture is left to stand for 22-25 hours after the mixing is completed.

[0009] In the above-mentioned method for preparing the vascular intima, the polytetrafluoroethylene powder is a polytetrafluoroethylene powder dispersion.

[0010] In the above-mentioned method for preparing the vascular intima, in step S1, the particle size of the polytetrafluoroethylene powder is in the range of 500-700 μm.

[0011] In the above-mentioned method for preparing the vascular sheath endothelium, in step S2, the density of the material rod is in the range of 1.5-1.65 g / cm³.

[0012] In the above-mentioned method for preparing the vascular intima, in step S3, a tensile force greater than 30 MPa is used for longitudinal stretching, and a tensile force greater than 6 MPa is used for transverse stretching.

[0013] Preferably, a tension of 30 MPa is used for longitudinal stretching and a tension of 6 MPa is used for transverse stretching. During the longitudinal and transverse stretching processes, the tension needs to be large enough to ensure that the polytetrafluoroethylene strip does not break during the stretching process.

[0014] In the above-mentioned method for preparing the vascular intima, in step S3, the preset temperature is 220-390°C, the time is maintained at 15-30 minutes, and the final thickness of the polytetrafluoroethylene tape is controlled to be 0.05-0.08 mm, and the density range is 0.65-0.75 g / cm³.

[0015] In the above-mentioned method for preparing the vascular intima, in step S4, the heat treatment time is as long as 30-60 minutes, and the heat treatment temperature is controlled at above 350°C.

[0016] In the above-mentioned method for preparing the vascular sheath intima, the liquid lubricant is aviation kerosene, and the mass ratio of the polytetrafluoroethylene powder to the liquid lubricant is 8:1.5-2.5.

[0017] Compared with the prior art, this application has the following advantages: This application innovatively changes the process to first extrude PTFE into strip materials, stretch them longitudinally and transversely, and then curl them and hot-melt splice them to form a tubular inner membrane. The strip pretreatment process eliminates the dependence on high-precision tubular extrusion equipment. By calendering the strip and controlling the splicing method, the uniformity of the inner membrane wall thickness is made better than that of traditional tubular extrusion solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a scanning electron microscope (SEM) image of the vascular intima of this application; Figure 2This is a schematic diagram of the application of rolling and splicing into a tubular membrane. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0020] In the present invention, unless otherwise specified, all parts and percentages are by weight. The equipment and raw materials used are commercially available or commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are all universal standard parts or components known to those skilled in the art. Their structures and principles are known to those skilled in the art through technical manuals or routine experimental methods.

[0021] In the existing technology, the traditional process of paste extrusion → pipe making → high temperature stretching and air blowing radial expansion → sintering and shaping is adopted, and the structure is directly used as a tubular finished product after it is formed.

[0022] This application innovatively changes the method to first extrude PTFE into strip materials, stretch them longitudinally and transversely, and then curl them and hot-melt splice them to form a tubular inner membrane. This solves the problems of high equipment precision requirements and poor consistency of pipe wall thickness in traditional extrusion molding, makes it easier to control the membrane thickness and pore structure, and improves the yield rate.

[0023] A method for preparing a vascular intimal sheath comprises the following steps: S1. Mixing polytetrafluoroethylene powder and liquid lubricant into a paste; S2, extruding the paste into a material rod, and rolling the material rod into a polytetrafluoroethylene tape; S3, stretching the polytetrafluoroethylene tape longitudinally and transversely at a preset temperature to form a microfiber structure on its surface and generate a porous network, wherein the liquid lubricant inside the tape is completely volatilized at the preset temperature; S4. Curling the sheet into a tube, and heat-treating the spliced ​​ends of the sheet to melt-splice them to form the vascular sheath endothelium.

[0024] In this application, steps S1-S3 are conventional steps, but some key parameters corresponding to S1-S3 are modified so that after longitudinal stretching and transverse stretching at a preset temperature, all liquid lubricants can be released, and a second heating can be performed for laying. After the hot melt splicing is completed, the microfiber structure and porous network will not be affected.

[0025] Specifically, in step S1, the polytetrafluoroethylene powder and the liquid lubricant are mixed at 23-25°C, and after the mixing is completed, the mixture is placed in an oven at 45-50°C for 22-25 hours.

[0026] Specifically, in step S1, the mixture is allowed to stand for 22-25 hours after the mixing is completed.

[0027] Specifically, the polytetrafluoroethylene powder is a polytetrafluoroethylene powder dispersion.

[0028] Specifically, in step S1, the particle size of the polytetrafluoroethylene powder is in the range of 500-700 μm.

[0029] Specifically, in step S2, the density of the rod is in the range of 1.5-1.65 g / cm³.

[0030] Specifically, in step S3, a tension greater than 30 MPa is used for longitudinal stretching, and a tension greater than 6 MPa is used for transverse stretching. After the longitudinal and transverse stretching are completed, it is necessary to ensure that the mesh size in the porous network is 0.5-30 microns.

[0031] Specifically, in step S3, the preset temperature is 220-390° C., the time is maintained at 15-30 minutes, and the thickness of the final polytetrafluoroethylene tape is controlled to be 0.05-0.08 mm, and the density range is 0.65-0.75 g / cm³.

[0032] Specifically, in step S4, the heat treatment time is 30-60 minutes, and the heat treatment temperature is controlled to be above 350° C. Preferably, the heat treatment temperature is controlled to be between 350° C. and 360° C.

[0033] Specifically, the liquid lubricant is aviation kerosene, and the mass ratio of the polytetrafluoroethylene powder to the liquid lubricant is 8:1.5-2.5. Preferably, the mass ratio of the polytetrafluoroethylene powder to the liquid lubricant is 8:2. Example 1

[0034] A method for preparing a vascular intimal sheath comprises the following steps: S1. Mixing polytetrafluoroethylene powder and liquid lubricant into a paste; the polytetrafluoroethylene powder and liquid lubricant are mixed at 23-25° C. and allowed to stand in an oven at 45-50° C. for 22-25 hours after mixing; the polytetrafluoroethylene powder is a polytetrafluoroethylene powder dispersion; the particle size of the polytetrafluoroethylene powder is in the range of 500-700 μm; the liquid lubricant is aviation kerosene, and the mass ratio of the polytetrafluoroethylene powder to the liquid lubricant is 8:2; S2. Extruding the paste into rods, and calendering the rods into polytetrafluoroethylene strips; the density of the rods is in the range of 1.5-1.65g / cm³; S3. Stretching the polytetrafluoroethylene strip longitudinally and transversely at a preset temperature to form a microfiber structure on its surface and generate a porous network, wherein the liquid lubricant inside the strip is completely volatilized at the preset temperature; a tensile force greater than 30 MPa is used for longitudinal stretching, and a tensile force greater than 6 MPa is used for transverse stretching; the preheating temperature is 220° C. and the time is maintained for 30 minutes, and the final thickness of the polytetrafluoroethylene strip is controlled to be 0.072-0.080 mm; and the density range is 0.65-0.70 g / cm³; S4. Curling the sheet into a tube, and subjecting the spliced ​​ends of the sheet to heat treatment to melt and splice them, thereby forming the vascular sheath tunica intima. The heat treatment time is as long as 30 minutes, and the heat treatment temperature is controlled at 350°C. Example 2

[0035] Compared with Example 1, the difference is: The preheating temperature is 390°C and the time is maintained at 15 minutes. The thickness of the final polytetrafluoroethylene strip is controlled at 0.072-0.080mm; the density range is 0.65-0.74g / cm³; The heat treatment time is as long as 60 minutes, and the heat treatment temperature is controlled at 350°C. Example 3

[0036] Compared with Example 1, the difference is: The preheating temperature is 260°C and the time is maintained at 18 minutes. The thickness of the final polytetrafluoroethylene strip is controlled to be 0.071-0.080mm; the density range is 0.67-0.70g / cm³; The heat treatment time is as long as 40 minutes, and the heat treatment temperature is controlled at 350°C. Example 4

[0037] Compared with Example 1, the difference is: The preheating temperature is 320°C and the time is maintained at 20 minutes. The thickness of the final polytetrafluoroethylene strip is controlled at 0.071-0.080mm; the density range is 0.65-0.68g / cm³; The heat treatment time is as long as 40 minutes, and the heat treatment temperature is controlled at 350°C. Example 5

[0038] Compared with Example 1, the difference is: The preheating temperature is 270°C and the time is maintained at 25 minutes. The thickness of the final polytetrafluoroethylene strip is controlled to be 0.070-0.078mm; the density range is 0.65-0.72g / cm³; The heat treatment time is as long as 40 minutes, and the heat treatment temperature is controlled at 350°C.

[0039] Table 1:

[0040] As shown in Table 1: In the state of Example 5, an inner film product with the best tensile strength and elongation at break can be obtained.

[0041] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a vascular intimal sheath, characterized in that: The following steps are involved: S1. Mixing polytetrafluoroethylene powder and liquid lubricant into a paste; S2, extruding the paste into a material rod, and rolling the material rod into a polytetrafluoroethylene tape; S3, stretching the polytetrafluoroethylene tape longitudinally and transversely at a preset temperature to form a microfiber structure on its surface and generate a porous network, wherein the liquid lubricant inside the tape is completely volatilized at the preset temperature; S4. Curling the sheet into a tube, and heat-treating the spliced ​​ends of the sheet to melt-splice them to form the vascular sheath endothelium.

2. The method for preparing the vascular intima according to claim 1, characterized in that: In step S1, the polytetrafluoroethylene powder and the liquid lubricant are mixed at 23-25°C, and after the mixing is completed, the mixture is placed in an oven at 45-50°C for 22-25 hours.

3. The method for preparing the vascular intima according to claim 1, characterized in that: In step S1, the mixture is allowed to stand for 22-25 hours after the mixing is completed.

4. The method for preparing the vascular intima according to claim 1, characterized in that: The polytetrafluoroethylene powder is a polytetrafluoroethylene powder dispersion.

5. The method for preparing the vascular intima according to claim 1, characterized in that: In step S1, the particle size of the polytetrafluoroethylene powder is in the range of 500-700 μm.

6. The method for preparing the vascular intima according to claim 1, characterized in that: In step S2, the density of the rod is in the range of 1.5-1.65 g / cm³.

7. The method for preparing the vascular intima according to claim 1, characterized in that: In step S3, a tensile force greater than 30 MPa is used for longitudinal stretching, and a tensile force greater than 6 MPa is used for transverse stretching.

8. The method for preparing the vascular intima according to claim 1, characterized in that: In step S3, the preset temperature is 220-390°C, the time is maintained at 15-30 minutes, and the thickness of the final polytetrafluoroethylene tape is controlled to be 0.05-0.08 mm, and the density range is 0.65-0.75 g / cm³.

9. The method for preparing the vascular intima according to claim 1, characterized in that: In step S4, the heat treatment time is 30-60 minutes, and the heat treatment temperature is controlled at above 350°C.

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