Preparation method of microcatheter with gradually-changed hardness

Abstract

The preparation method comprises the following steps: S1, coating an inner layer: taking a core rod as a supporting piece, and coating the surface of the core rod with a PTFE (Polytetrafluoroethylene) material to form the inner layer; s2, weaving of a middle reinforcing layer: performing three-dimensional weaving or spiral winding of metal wires on the surface of the inner layer to form the middle reinforcing layer and a first semi-finished pipe; the surface of the first semi-finished pipe is coated with a high polymer material through extrusion equipment, so that an outer layer is formed on the surface of the first semi-finished pipe, and a second semi-finished pipe is formed; s4, soft section treatment: dissolving the head end of the second semi-finished pipe by using an organic solvent, removing a covering film on the head end of the second semi-finished pipe, and exposing a middle reinforcing layer; and S5, forming is conducted, specifically, a low-modulus section is arranged on the exposed middle reinforcing layer to form the head end of the catheter, the core rod is pulled away to form the hollow finished catheter, the end of the catheter is dissolved through an organic solvent, and the catheter is milder and more efficient.

Description

Technical Field

[0001] The invention relates to the technical field of medical devices, and in particular to a method for preparing a micro-catheter with gradually changing softness and hardness. Background Art

[0002] In the field of human interventional treatment, medical catheters are commonly used medical tools. In cerebrovascular interventional surgery, catheter products are mainly responsible for the construction of surgical access, the delivery of implantable devices, the injection of diagnostic reagents, and the direct aspiration of blood clots. Their frequency of use is very high.

[0003] Among them, the soft and hard gradient microcatheter is a specially designed catheter aimed at improving its operability and safety in complex vascular anatomical structures. The design idea of ​​this catheter is to achieve changes in softness and hardness along its length so as to better adapt to different operational requirements.

[0004] The design concept of the soft-hardness gradient microcatheter is to adjust the material properties and structure of different parts of the catheter so that it exhibits different degrees of hardness in different operation stages. This design can make the catheter more flexible after entering the human body, reduce damage to the blood vessel wall, and improve the doctor's control accuracy.

[0005] The existing manufacturing process of soft and hard gradient microcatheters generally involves first coating PTFE on the core wire, then weaving a reinforcement layer onto the PTFE layer, and using an extrusion device to cover the braided layer with a polymer film. Finally, a portion of the polymer film is removed with a laser, and the removed area is dip-coated with other low-hardness materials to form a low-hardness head end. However, in the actual production process, the laser method may break the braided wire on the reinforcement layer, and the efficiency is very low and the energy consumption is very high. Summary of the invention

[0006] In order to solve the technical problems existing in the background technology, the present invention proposes a method for preparing a microcatheter with gradually changing softness and hardness.

[0007] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0008] A method for preparing a soft and hardness-gradient microcatheter comprises the following steps:

[0009] S1. Coating the inner layer: Take a core rod as a support member, and coat the surface of the core rod with PTFE material to form an inner layer;

[0010] S2, intermediate reinforcement layer weaving: three-dimensional weaving or spiral winding of metal wires is performed on the surface of the inner layer to form an intermediate reinforcement layer and a first semi-finished tube;

[0011] S3, outer layer coating: using an extrusion device to coat the surface of the first semi-finished tube with a polymer material to form an outer layer on the surface of the first semi-finished tube and form a second semi-finished tube;

[0012] S4, soft section treatment: using an organic solvent to dissolve the head end of the second semi-finished pipe, removing the coating on the head end of the second finished pipe, and exposing the middle reinforcement layer;

[0013] S5. Forming: A low modulus section is arranged on the exposed middle reinforcement layer to form the head end of the catheter, and the core rod is removed to form a hollow finished catheter.

[0014] Preferably, in step S5, a low modulus solution is sprayed on the exposed intermediate reinforcing layer to form a low modulus segment, and the intermediate reinforcing layer and the outer layer are joined. The low modulus solution is PEBA or PU solution. Through the above improvements, a softer PEBA or PU solution is used to form the head end of the catheter, so that the head end of the catheter is relatively soft to reduce irritation and wear on the blood vessel wall, especially when passing through narrow or curved blood vessels, thereby greatly improving the safety of the operation.

[0015] Preferably, in step S5, a heat shrink tube is sleeved on the exposed intermediate reinforcement layer, and a heating device is used to heat the sleeve so that it shrinks and fits tightly to the intermediate reinforcement layer and the outer layer to form a low modulus section. Through the above improvements, a relatively soft heat shrink tube is selected and sleeved on the exposed intermediate reinforcement layer. A hot air gun, an oven or other heating equipment is used to heat the heat shrink tube so that it shrinks and fits tightly to the intermediate reinforcement layer and the outer layer to form the head end of the catheter, thereby making the head end of the catheter softer.

[0016] Preferably, the heat shrink tube adopts PEBA or PU. Through the above improvements, the PEBA material has excellent softness, so that the heat shrink tube can pass through the wrapped object when bending and winding, and is not easy to break or damage. In addition, the PEBA material is harmless to the human body and is suitable for cable protection and sealing of medical devices. The PU heat shrink tube has the characteristics of high elasticity, high elongation and high strength. These thermal properties enable it to perform well in various applications and can meet the complex environment of the grid. It not only ensures the elasticity of the catheter head end, but also has good biocompatibility, ensuring the safety of the catheter during surgery.

[0017] Preferably, in step S5, an adhesive is applied on the exposed intermediate reinforcement layer, and the adhesive is bonded to the heat shrink tube. Through the above improvements, in certain usage scenarios, in order to enhance the adhesion between the heat shrink tube and the intermediate reinforcement layer, a layer of adhesive can be coated on the surface of the inner lining tube before heat shrinking, thereby increasing the reliability of the installation of the heat shrink tube.

[0018] Preferably, the polymer material in step S3 is TPU or nylon. Through the above improvements, the structural strength of the proximal end and the transition section of the catheter is ensured.

[0019] Preferably, the organic solution in step S4 is a DMF solvent. Through the above improvement, the outer layer of the catheter tip is dissolved by an organic solvent such as DMF to expose the braided layer, which is gentler and more efficient than laser cutting.

[0020] Preferably, the metal wire in step S2 is a stainless steel wire or a nickel-titanium memory alloy. Through the above improvements, the structural strength of the middle reinforcement layer is greatly improved to ensure the structural strength and service life of the catheter.

[0021] Preferably, in step S5, a developing material is mixed into the low modulus solution, and the developing material is tungsten powder, and the material of the low modulus segment is PEBA or PU material, and a certain amount of PEBA or PU, tungsten powder, and a solvent are placed in a mixing container, so that the low modulus material and tungsten powder are completely dissolved in the solvent to form a low modulus solution with a developing effect. Through the above improvement, the low modulus solution with a developing effect is dipped or sprayed onto the exposed intermediate reinforcement layer to form the head end of the catheter, so that the head end of the catheter has a developing effect, thereby further improving the safety of the catheter during use and ensuring the bonding effect of the low modulus segment with the intermediate reinforcement layer and the outer layer.

[0022] Preferably, a plurality of embedding holes are formed on the intermediate reinforcing layer, and the low modulus solution is injected into the embedding holes so that the low modulus segment joins the intermediate reinforcing layer and the outer layer. Through the above improvement, the low modulus solution will be embedded in the embedding holes and join with the intermediate reinforcing layer, thereby further improving the structural strength of the intermediate reinforcing layer.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] PTFE material is first coated on the core rod to form the inner layer of the catheter, and metal wire is used for three-dimensional weaving on the inner layer to form an intermediate reinforcement layer, and then a polymer material is coated on the intermediate reinforcement layer using an extrusion device. Finally, an organic solvent is used to dissolve the coating at the head end of the catheter, and the intermediate reinforcement layer is exposed. A low-hardness, low-modulus section is provided on the exposed intermediate reinforcement layer to make the head end of the catheter softer to reduce stimulation and damage to the blood vessel wall, especially when it needs to pass through narrow or curved blood vessels, thereby improving the safety of the catheter during use. In addition, the use of an organic solvent to dissolve the end of the catheter is more gentle and efficient. Compared with using a laser to cut the outer layer, it can avoid the generation of harmful substances such as smoke, volatile organic compounds, and particulate matter, and avoid harmful substances remaining on the catheter to cause damage to the human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the overall structure of the present invention;

[0026] Figure 2 It is an axial cross-sectional view of the overall structure of the present invention;

[0027] Figure 3 It is a radial cross-sectional view of the overall structure of the present invention;

[0028] In the figure: 1, inner layer; 2, middle reinforcement layer; 3, outer layer; 4, head end; 5, embedding hole. DETAILED DESCRIPTION

[0029] The following will be combined with the 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 without creative work are within the scope of protection of the present invention.

[0030] It should be understood that although the terms upper, middle, lower, top, end, etc. appear in this article to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish elements from each other for easy understanding, and are not used to define any direction or order limitation.

[0031] Embodiment 1

[0032] like Figure 1-Figure 3 As shown, a method for preparing a microcatheter with a gradual change in softness and hardness is characterized in that it comprises the following steps:

[0033] S1, coating inner layer 1: taking a core rod as a support member, and coating the surface of the core rod with PTFE material to form inner layer 1;

[0034] S2, weaving of the middle reinforcement layer 2: three-dimensional weaving or spiral winding of metal wires is performed on the surface of the inner layer 1 to form the middle reinforcement layer 2 and the first semi-finished tube;

[0035] S3, coating of outer layer 3: using an extrusion device to coat the surface of the first semi-finished tube with a polymer material to form an outer layer 3 on the surface of the first semi-finished tube and form a second semi-finished tube;

[0036] S4, soft section treatment: using an organic solvent to dissolve the head end 4 of the second semi-finished tube, removing the coating on the head end 4 of the second finished tube, and exposing the intermediate reinforcement layer 2;

[0037] S5, molding: a low modulus segment is arranged on the exposed middle reinforcing layer 2, the low modulus segment adopts a soft segment polymer material to form the head end 4 of the catheter, and the core rod is removed to form a hollow finished catheter.

[0038] Using organic solvents to dissolve the end of the catheter is more gentle and efficient. Compared with laser cutting, it can avoid the generation of harmful substances such as smoke, volatile organic compounds, particulate matter, and avoid harmful substances remaining on the catheter and causing damage to the human body.

[0039] In step S5, a low modulus solution is sprayed on the exposed intermediate reinforcing layer 2 to form a low modulus segment, and the intermediate reinforcing layer 2 and the outer layer 3 are joined. The low modulus solution is a PEBA or PU solution, so that the head end 4 of the entire catheter is relatively soft to reduce irritation and wear on the blood vessel wall, especially when passing through narrow or curved blood vessels, thereby greatly improving the safety of the operation.

[0040] Specifically, the polymer material in step S3 is TPU or nylon, which ensures the structural strength of the proximal end and the transition section of the catheter.

[0041] Preferably, the organic solution in step S4 is a DMF solvent. Using an organic solvent such as DMF to dissolve the outer layer 3 and expose the braided layer is gentler and more efficient than laser cutting.

[0042] Preferably, the metal wire in step S2 is a stainless steel wire or a nickel-titanium memory alloy, which greatly improves the structural strength of the middle reinforcement layer 2 to ensure the structural strength and service life of the catheter.

[0043] Embodiment 2

[0044] The difference between this embodiment and the first embodiment is that, in step S5, a heat shrink tube is sleeved on the exposed intermediate reinforcement layer 2, and the sleeve is heated by a heating device to shrink and fit tightly to the intermediate reinforcement layer 2 and the outer layer 3 to form a low modulus section, and the low modulus section constitutes the head end 4 of the catheter.

[0045] During the molding process of the head end, a relatively soft heat shrink tube is selected and put on the exposed middle reinforcement layer 2, and then the heat shrink tube is heated using a hot air gun, oven or other heating equipment to shrink it and fit tightly on the inner lining tube of the catheter, thereby making the outer end of the catheter softer.

[0046] Preferably, the heat shrink tube is made of PEBA or PU material. PEBA material has excellent softness, which enables the heat shrink tube to pass through the wrapped object when bending and winding, and is not easy to break or damage. PEBA material is harmless to the human body and is suitable for cable protection and sealing of medical devices. PU heat shrink tube has the characteristics of high elasticity, high elongation and high strength. These thermal properties enable it to perform well in various applications and can meet the complex environment of the grid. It not only ensures the elasticity of the catheter head, but also has good biocompatibility, ensuring the safety of the catheter during surgery.

[0047] Preferably, during the bonding process of the heat shrink tube and the intermediate reinforcing layer 2, an adhesive can be coated on the intermediate reinforcing layer 2 exposed in step S5, and the adhesive bonds to the heat shrink tube to enhance the adhesion between the heat shrink tube and the intermediate reinforcing layer 2, thereby increasing the reliability of the heat shrink tube installation and preventing the heat shrink tube from detaching.

[0048] Embodiment 3

[0049] The difference between this embodiment and the first embodiment is that in step S5, a developing material is mixed into a low modulus solution, and the developing material is tungsten powder, the developing material and the low modulus solution are mixed to form a low modulus solution with a developing effect, and the low modulus solution is dip-coated onto the exposed intermediate reinforcing layer 2 to form the head end of the catheter, so that the head end of the catheter has a developing effect, thereby further improving safety.

[0050] Furthermore, a plurality of embedding holes 5 are formed on the middle reinforcing layer 2 , and a low modulus solution is injected into the embedding holes 5 , so that the low modulus segment joins the middle reinforcing layer 2 and the outer layer 3 , further improving the structural strength of the middle reinforcing layer 2 .

[0051] PEBA or PU, tungsten powder, and solvent are weighed according to the ratio, and a certain amount of PEBA or PU, tungsten powder, and solvent are placed in a mixing container and stirred sufficiently to completely dissolve PEBA or PU and tungsten powder in the solvent to form a low modulus solution with a developing effect, and the low modulus solution is sprayed or dipped on the head end of the catheter. After the low modulus solution solidifies, the head end of the catheter is formed, and the head end of the catheter has a developing effect, thereby further improving safety and improving the bonding effect between the low modulus segment and the middle reinforcement layer 2 and the outer layer 3.

[0052] Embodiment 4

[0053] The difference between this embodiment and the first embodiment is that in S5, a plurality of low modulus solutions of different hardness are coated on the exposed intermediate reinforcing layer 2, and the hardness of the low modulus solution gradually decreases from the proximal end to the distal end, thereby gradually reducing the hardness of the catheter tip.

[0054] Embodiment 5

[0055] The difference between this embodiment and the first embodiment is that in the S3 outer layer 3 coating, the first semi-finished tube is placed into the extrusion equipment multiple times, and the coating is performed in sections, and polymer materials with different hardness are used, and the hardness of the polymer material gradually decreases from the proximal end to the distal end, so that the entire catheter has an effect of gradually decreasing hardness.

[0056] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for preparing a microcatheter with gradually varying hardness and softness, characterized in that: The following steps are involved: S1, coating the inner layer (1): taking a core rod as a support member, and coating the surface of the core rod with PTFE material to form the inner layer (1); S2, weaving of the intermediate reinforcement layer (2): three-dimensionally weaving or spirally winding the metal wires on the surface of the inner layer (1) to form the intermediate reinforcement layer (2) and the first semi-finished tube; S3, outer layer (3) coating: using an extrusion device to coat the surface of the first semi-finished tube with a polymer material to form an outer layer (3) on the surface of the first semi-finished tube and to form a second semi-finished tube; S4, soft section treatment: using an organic solvent to dissolve the head end (4) of the second semi-finished tube, removing the coating on the head end (4) of the second finished tube, and exposing the intermediate reinforcement layer (2); S5. Forming: a low modulus section is arranged on the exposed intermediate reinforcing layer (2) to form the head end (4) of the conduit, and the core rod is removed to form a hollow finished conduit.

2. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 1, characterized in that: In step S5, a low modulus solution is sprayed on the exposed middle reinforcing layer (2) to form a low modulus section and to join the middle reinforcing layer (2) and the outer layer (3), wherein the low modulus solution is a PEBA or PU solution.

3. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 1, characterized in that: In step S5, a heat shrink tube is sleeved on the exposed middle reinforcing layer (2), and the sleeve is heated using a heating device to shrink and fit tightly to the middle reinforcing layer (2) and the outer layer (3) to form a low modulus section.

4. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 3, characterized in that: The heat shrink tube is made of PEBA or PU material.

5. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 3, characterized in that: In step S5, a bonding agent is applied on the exposed intermediate reinforcement layer (2), and the bonding agent is bonded to the heat shrink tube.

6. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 1, characterized in that: The polymer material in step S3 is TPU or nylon.

7. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 1, characterized in that: The organic solution in step S4 is DMF solvent.

8. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 1, characterized in that: The metal wire in step S2 is a stainless steel wire or a nickel-titanium memory alloy.

9. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 2, characterized in that: In step S5, a developing material is mixed into the low modulus solution, and the developing material is tungsten powder, and the material of the low modulus segment is PEBA or PU. A certain amount of PEBA or PU, tungsten powder, and a solvent are placed in a mixing container, so that the low modulus material and tungsten powder are completely dissolved in the solvent to form a low modulus solution with a developing effect.

10. The method for preparing a microcatheter with gradually varying hardness and softness according to claim 9, characterized in that: A plurality of embedding holes (5) are formed on the intermediate reinforcing layer (2), and the low modulus solution is injected into the embedding holes (5) so that the low modulus segment joins the intermediate reinforcing layer (2) and the outer layer (3).

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