A method for membrane treatment of a covered stent product

Abstract

The present invention relates to a method for treating the film of a covered stent product, belonging to the technical field of medical devices. It includes successively manufacturing a metal mold with patterns, hot-pressing a silicone rubber soft mold with patterns using the metal mold, and forming a printed film by sleeving a polyurethane film on the silicone rubber soft mold; sleeving the printed film on the outer periphery of a metal stent, performing heat shrinkage tube heating and cooling treatment, and then peeling off the silicone rubber soft mold, leaving only the metal stent wrapped with the polyurethane film printed with a pattern structure. Through the special treatment process provided by the present invention, tiny boss structures are printed on the surface of the film of the covered stent, and these boss structures will greatly increase the contact area between the film and the target cavity, thereby increasing the static friction coefficient to solve the technical problems of "displacement and shedding" of the covered stent.

Description

Technical Field

[0001] The present invention relates to a film treatment method for a covered stent product, belonging to the technical field of medical devices. Background Art

[0002] In order to treat various benign or malignant diseases of lumen stenosis, stents have been widely used in clinical practice since the 1980s. They are commonly used medical devices in current interventional surgeries and are widely applied in the fields of cardiovascular, digestive, respiratory, and urology. The main materials of stents are stainless steel, nitinol alloy, cobalt-chromium alloy, etc., which are placed at the target stenosis position through interventional means by weaving or cutting. Since the natural lumens of the human body such as blood vessels, esophagus, airway, bronchus, urethra, and ureter will produce endothelial hyperplasia reaction after being compressed by the metal mesh, a large number of restenosis cases occur. Due to the defect that bare metal stents are prone to restenosis, stents have evolved from bare metal stents to polymer-covered stents. The materials used for covering the film include polyurethane, silicone rubber, expanded polytetrafluoroethylene, etc. The polymer film on the surface of the stent can well prevent the growth of proliferative tissue into the interior of the metal mesh, thus greatly reducing the occurrence of restenosis. However, the polymer film reduces the static friction coefficient between the stent and the target lumen, and the covered stent is more likely to have problems of "displacement and shedding" under the condition of the same radial supporting force. Therefore, it is urgent to solve the technical problem of "displacement and shedding" of covered stents in this technical field. Summary of the Invention

[0003] The purpose of the present invention is to solve the technical problem of how to avoid the "displacement and shedding" of covered stents.

[0004] To achieve the purpose of solving the above problems, the technical solution adopted by the present invention is to provide a film treatment method for a covered stent product, including the following steps:

[0005] Step 1: Fabricate a metal mold; a fine carving structure with multiple bosses is processed on the surface of the metal mold;

[0006] Step 2: Fabricate a silicone rubber soft mold; fill the uncured silicone rubber onto the metal mold, and generate a silicone rubber soft mold with multiple grooves through hot pressing; then process the silicone rubber soft mold into a cylindrical silicone rubber soft mold ring with grooves on the inner surface;

[0007] Step 3: Fabricate a printing film; sleeved a cylindrical target polyurethane film ring on a cylindrical tooling, sleeved a silicone rubber soft mold ring on the outer periphery of the polyurethane film ring, with the grooved side of the silicone rubber soft mold ring facing the polyurethane film ring, and then sleeved a heat shrinkable tube on the outermost side; heat the entire tooling, and the heat shrinkable tube forms pressure to press the molten polyurethane film into the grooves of the silicone rubber soft mold ring; after cooling, remove the heat shrinkable tube, and then remove the polyurethane film ring from the cylindrical tooling together with the silicone rubber soft mold ring;

[0008] Step 4: Film laminating; sleeving the polyurethane film ring obtained in Step 3 on the outer periphery of the metal stent, and wrapping another silicone film layer outside the silicone soft mold ring; supporting a support member between two layers of the stent at one end of the metal stent; sleeving a heat-shrinkable tube on the outermost silicone film layer, heating the entire tooling, and then cooling, peeling off the heat-shrinkable tube, and stripping the silicone mold, leaving only the metal stent wrapped by the polyurethane film ring;

[0009] Step 5: Heat-melt the film onto the stent.

[0010] Preferably, the fine carving structure with multiple bosses processed on the surface of the metal mold in Step 1 is processed by a precision machining center.

[0011] Preferably, in Step 2, the vulcanization temperature for thermoforming is 110 - 120 °C, the pressure is 5 - 8 MPa, and the time is 6 - 8 min; the diameter of the silicone soft mold ring is 6 - 25 mm.

[0012] Preferably, the heat-shrinkable tube in Step 3 is an FEP heat-shrinkable tube with a heat shrinkage ratio of 1.6:1.

[0013] Preferably, heating the entire tooling in Step 3 is to place the tooling in an oven at 165 - 205 °C for 60 - 110 seconds.

[0014] Preferably, the silicone film layer in Step 4 is 0.1 mm thick.

[0015] Preferably, the heat-shrinkable tube in Step 4 is an FEP heat-shrinkable tube with a heat shrinkage ratio of 1.3:1.

[0016] Preferably, heating the entire tooling in Step 4 is to first preheat with a hot air gun, and the preheating temperature is 200 °C; then place it in an oven at 205 °C for 2 minutes and 15 seconds; cooling is to take it out and let it cool naturally for 5 min after the time; when heating the entire tooling, use a heat-shrinkable tube and PTFE coating tape to protect the whole tooling, and the heat-shrinkable tube for protection is sealed with a silicone cap.

[0017] Preferably, in Step 5, heat-melting the film onto the stent is to use a spot welder to heat-melt the film onto the stent.

[0018] The present invention provides a covered stent manufactured by a film treatment method for the covered stent product according to the above, and the polymer film of the covered stent is provided with a pattern structure for increasing the static friction coefficient between the stent and the target channel.

[0019] Preferably, the polymer film of the covered stent is 0.02 - 0.08 mm thick, and the film is provided with multiple boss structures with a diameter of 0.01 - 0.04 mm, and the distance between each boss structure is 0.02 - 0.04 mm; the height of the boss structure is 0.005 - 0.01 mm.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a printed polymer-coated metal stent with a plurality of boss structures having a diameter of 0.01 - 0.04 mm, a pitch of 0.02 - 0.04 mm, and a height of 0.005 - 0.01 mm formed on a polymer film with a thickness of 0.02 - 0.08 mm; by a special treatment process, tiny boss structures are printed on the surface of the film, and these boss structures will greatly increase the contact area between the film and the target cavity, thereby enhancing the static friction coefficient to solve the technical problems of "displacement and shedding" of the coated stent. Detailed implementation manners

[0022] To make the present invention more obvious and understandable, the following is a detailed description with preferred embodiments:

[0023] The present invention provides a method for treating the film of a coated stent product, including the following steps:

[0024] Step 1: Fabricate a metal mold; a precision carving structure with a plurality of bosses is machined on the surface of the metal mold;

[0025] Step 2: Fabricate a silicone rubber soft mold; fill uncured silicone rubber into the metal mold, and a silicone rubber soft mold with a plurality of grooves is produced by hot pressing; then the silicone rubber soft mold is processed into a cylindrical silicone rubber soft mold ring with grooves on the inner surface;

[0026] Step 3: Fabricate a printed film; sleeved a cylindrical target polyurethane film ring on a columnar tooling, sleeved a silicone rubber soft mold ring on the outer periphery of the polyurethane film ring, the side of the silicone rubber soft mold ring with grooves faces the polyurethane film ring, and then sleeved a heat shrinkable tube on the outermost side; heat the entire tooling, and the heat shrinkable tube forms pressure to press the molten polyurethane film into the grooves of the silicone rubber soft mold ring; after cooling, remove the heat shrinkable tube, and then remove the polyurethane film ring from the columnar tooling together with the silicone rubber soft mold ring;

[0027] Step 4: Coating; sleeved the polyurethane film ring obtained in Step 3 on the outer periphery of the metal stent, and wrapped another silicone film layer on the outer side of the silicone rubber soft mold ring; support a support member between the two layers of the stent at one end of the metal stent; sleeved the heat shrinkable tube on the outermost silicone film layer, heat the entire tooling, then cool, remove the heat shrinkable tube, and peel off the silicone mold, leaving only the metal stent wrapped by the polyurethane film ring;

[0028] Step 5: Melt the film onto the stent.

[0029] The precision carving structure with a plurality of bosses machined on the surface of the metal mold in the above Step 1 is formed by a precision machining center.

[0030] In the above step 2, the vulcanization temperature for hot press forming is 110 - 120 °C, the pressure is 5 - 8 MPa, and the time is 6 - 8 min; the diameter of the silicone rubber soft mold ring is 6 - 25 mm.

[0031] In the above step 3, the heat shrinkable tube is an FEP heat shrinkable tube with a heat shrinkage ratio of 1.6:1.

[0032] In the above step 3, heating the entire tooling is to place the tooling in an oven at 165 - 205 °C for 60 - 110 seconds.

[0033] In the above step 4, the silicone rubber film layer is 0.1 mm thick.

[0034] In the above step 4, the heat shrinkable tube is an FEP heat shrinkable tube with a heat shrinkage ratio of 1.3:1.

[0035] In the above step 4, heating the entire tooling is to first preheat it with a hot air gun at a preheating temperature of 200 °C; then place it in an oven at a temperature of 205 °C for 2 minutes and 15 seconds; after cooling, take it out and let it cool naturally for 5 minutes; when heating the entire tooling, use a heat shrinkable tube and PTFE coating tape to protect the whole tooling, and the protective heat shrinkable tube is sealed with a silicone cap.

[0036] In the above step 5, melting the film onto the bracket is to use a spot welder to melt the film onto the bracket.

[0037] The present invention provides a covered stent manufactured by a film treatment method for the covered stent product according to the above, and the polymer film of the covered stent is provided with a pattern structure for increasing the static friction coefficient between the stent and the target lumen.

[0038] The polymer film of the covered stent is 0.02 - 0.08 mm thick, and the film is provided with a plurality of boss structures with a diameter of 0.01 - 0.04 mm, and the distance between each boss structure is 0.02 - 0.04 mm; the height of the boss structure is 0.005 - 0.01 mm.

[0039] Example

[0040] The present invention provides a film treatment method for a covered stent product, including the following steps:

[0041] 1. Fabricate a metal mold: A fine carving structure with a plurality of boss structures is machined on the surface of the metal mold through a precision machining center.

[0042] 2. Fabricate a silicone rubber soft mold: Fill the uncured silicone rubber into the metal mold, and through hot press forming, with a vulcanization temperature of 110 - 120 °C, a pressure of 5 - 8 MPa, and a time of 6 - 8 min, a silicone rubber soft mold with grooves is produced. Process the silicone rubber soft mold into a silicone rubber soft mold ring with a diameter of 6 - 25 mm.

[0043] 3. Making the printing film: A target polyurethane film ring (with a diameter of 10 - 16 mm) used for laminating the stent is sleeved on a polytetrafluoroethylene cylindrical tooling (with a diameter of 10 - 16 mm). The above-mentioned silicone soft mold ring is sleeved on the outer periphery of the polyurethane film ring, and the side of the silicone soft mold ring with grooves faces the polyurethane film ring. An FEP heat shrinkable tube with a heat shrinkage ratio of 1.6:1 is further sleeved on the outermost side of the silicone soft mold ring. The polytetrafluoroethylene cylindrical tooling is placed in an oven at 165 - 205 °C for 60 - 110 seconds. The pressure formed by the heat shrinkable tube presses the melted polyurethane film into the grooves of the silicone soft mold ring. After cooling, the heat shrinkable tube is removed, and the polyurethane film ring is removed from the polytetrafluoroethylene cylindrical tooling together with the silicone soft mold ring.

[0044] 4. Laminating process: First, a cylindrical polyurethane film ring (with an outer silicone soft mold ring) is sleeved on the outer periphery of a cylindrical hollow nitinol stent (located on the outside of the stent). A 0.1 mm thick silicone film layer is wrapped on the outside of the silicone soft mold ring; A 15 mm diameter FEP tube is supported between two layers of the stent at the proximal end of the nitinol stent;

[0045] Prepare an FEP heat shrinkable tube with an outer diameter of 22 mm and a heat shrinkage ratio of 1.3:1, cut a 5 mm length, and prepare a hot air gun with the temperature adjusted to 200 °C.

[0046] The 5 mm long heat shrinkable tube is sleeved on the outer periphery of the outer silicone film layer, and the lower edge of the 5 mm long heat shrinkable tube is aligned with the proximal edge of the stent, and pre-shrinking is carried out using a hot air gun.

[0047] The overall tooling is protected using heat shrinkable tubes and PTFE coated tapes. The length of the protective heat shrinkable tube is 100 mm, and both are sealed with silicone caps.

[0048] The entire tooling is placed in an oven at a temperature of 205 °C for 2 m 15 s. After the time is up, take it out and let it cool naturally for 5 min. Remove the protective heat shrinkable tube and the pressure-applying heat shrinkable tube, and finally peel off the silicone mold. Use a spot welder to melt the film onto the stent.

[0049] As described above, it is only the preferred embodiment of the present invention, and there is no limitation in any form and substance to the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the premise of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. For those skilled in the art, without departing from the spirit and scope of the present invention, any equivalent changes made by using the technical content disclosed above, such as slight changes, modifications, and evolutions, are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for treating the membrane of a covered stent product, characterized in that, Including the following steps: Step 1: Fabricate a metal mold; a fine carving structure with multiple bosses is machined on the surface of the metal mold; Step 2: Fabricate a silicone rubber soft mold; fill the uncured silicone rubber onto the metal mold, and generate a silicone rubber soft mold with multiple grooves through hot pressing; Then process the silicone rubber soft mold into a cylindrical silicone rubber soft mold ring with grooves on the inner surface; Step 3: Fabricate a printing film; sleeved a cylindrical target polyurethane film ring on a cylindrical tooling, sleeved a silicone rubber soft mold ring on the outer periphery of the polyurethane film ring, the side with grooves of the silicone rubber soft mold ring is attached to the polyurethane film ring, and then sleeved a heat shrinkable tube on the outermost side; heat the entire tooling, and the heat shrinkable tube forms pressure to press the melted polyurethane film into the grooves of the silicone rubber soft mold ring; After cooling, remove the heat shrinkable tube, and then remove the polyurethane film ring from the cylindrical tooling together with the silicone rubber soft mold ring; Step 4: Film laminating; sleeved the polyurethane film ring obtained in Step 3 on the outer periphery of the metal bracket, wrap another layer of silicone film layer on the outside of the silicone rubber soft mold ring; support a support member between two layers of brackets at one end of the metal bracket; sleeved the heat shrinkable tube on the outermost silicone film layer, heat the entire tooling, then cool, remove the heat shrinkable tube, peel off the silicone mold, and only leave the metal bracket wrapped by the polyurethane film ring; Step 5: Use a spot welder to heat-melt the film onto the bracket.

2. The film treatment method of a covered stent product according to claim 1, characterized in that The fine carving structure with multiple bosses machined on the surface of the metal mold in Step 1 is processed by a precision machining center.

3. The film treatment method of a covered stent product according to claim 1, characterized in that, In Step 2, the vulcanization temperature of the hot pressing is 110 - 120 °C, the pressure is 5 - 8 MPa, and the time is 6 - 8 min; the diameter of the silicone rubber soft mold ring is 6 - 25 mm.

4. The film treatment method of a covered stent product according to claim 1, wherein, In Step 3, the heat shrinkable tube is an FEP heat shrinkable tube with a heat shrinkage ratio of 1.6:

1.

5. A method for film treatment of a covered stent product according to claim 1, characterized in that, In Step 3, heating the entire tooling means putting the tooling into an oven at 165 - 205 °C for 60 - 110 seconds.

6. A method for treating the membrane of a covered stent product according to claim 1, characterized in that, In Step 4, the silicone film layer is 0.1 mm thick.

7. A membrane treatment method for a covered stent product according to claim 1, characterized in that, In Step 4, the heat shrinkable tube is an FEP heat shrinkable tube with a heat shrinkage ratio of 1.3:

1.

8. A method for treating the membrane of a covered stent product according to claim 1, characterized in that, In Step 4, heating the entire tooling is to first preheat with a hot air gun, and the preheating temperature is 200 °C; then put it into an oven at 205 °C for 2 minutes and 15 seconds; cooling means taking it out and cooling naturally for 5 min after the time; when heating the entire tooling, use the heat shrinkable tube and PTFE coating tape to protect the whole tooling, and the protective heat shrinkable tube is sealed with a silicone cap.