Carbon fiber skeleton medical catheter and preparation method thereof

Abstract

The invention relates to a carbon fiber skeleton medical catheter and a preparation method thereof.The carbon fiber skeleton medical catheter comprises a hollow catheter body and a handle, the catheter body comprises an inner-layer tube, a middle-layer tube and an outer-layer tube, the middle-layer tube is a carbon fiber tube, and the outer-layer tube is a carbon fiber tube; the middle-layer tube comprises a near-end section connected with the handle and a far-end section on the other side, the far-end section is provided with a plurality of slits communicated with an inner cavity of the catheter, an included angle is formed between the extending direction of the slits and the axial direction of the catheter, and the slits are filled with thermoplastic elastomers.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical devices, in particular to a carbon fiber framework medical catheter and a preparation method thereof. BACKGROUND

[0002] Currently, medical catheter products generally use nickel-titanium alloy or stainless steel as the intermediate reinforcing layer, and are usually formed into a tube support framework in the form of a braided structure, a spring structure or a mixed form of both. Although metal materials can provide basic radial support, the inherent characteristics of metal materials and the existing structure design lead to a series of technical bottlenecks. For a spring structure catheter, the tensile strength of the distal end depends entirely on the inner and outer layer of high polymer materials (such as polyether block amide), and the axial tensile strength of the high polymer material is usually not more than 20 MPa, and the elongation at break is as high as 300%-500%. When the catheter is stuck with other interventional instruments in the blood vessel, the tensile force generated by the clinical withdrawal operation is likely to cause the distal end of the catheter to break, and the broken free section may cause thrombosis, and in severe cases, surgical removal is required.

[0003] In addition, for a catheter with a braided structure, repeated cross nodes can cause the catheter to lose some flexibility, causing damage to the blood vessel wall when the catheter passes through a tortuous blood vessel. In addition, the metal stacking at the cross point increases the additional thickness, resulting in a loss of effective lumen of the catheter and reducing the pumping efficiency. In the processing process, the spring structure requires a long spring winding process, which increases the manufacturing time and cost of the catheter.

[0004] Therefore, it is necessary to provide a carbon fiber framework medical catheter and a preparation method thereof. SUMMARY

[0005] Based on this, it is necessary to provide a carbon fiber framework medical catheter and a preparation method thereof.

[0006] The first aspect of the present application provides a carbon fiber framework medical catheter, comprising a hollow catheter body and a handle, the catheter body comprising an inner layer tube, an intermediate layer tube and an outer layer tube, the intermediate layer tube being a carbon fiber tube, the intermediate layer tube comprising a proximal end segment connected with the handle and a distal end segment on the other side, the distal end segment being provided with a plurality of slits in communication with the inner lumen of the catheter, the extension direction of the slits being arranged at an angle with the axial direction of the catheter, and the slits being filled with a thermoplastic elastomer.

[0007] The carbon fiber skeleton medical catheter uses a carbon fiber tube to replace traditional metal materials as an intermediate reinforcing layer, and combines a specific angle slit structure filled with a thermoplastic elastomer at the distal end. Compared with metal materials, carbon fiber has higher axial tensile strength and excellent fatigue resistance, which helps to reduce the risk of catheter distal end fracture caused by tension during withdrawal operation, thereby reducing the possibility of complications such as thrombosis or surgical removal of the broken free section. The high specific modulus characteristics of carbon fiber enable it to provide sufficient radial support while achieving a thinner tube wall thickness, increasing the effective lumen of the catheter, and improving the pumping efficiency. The carbon fiber tube distal end section is processed with a slit at an angle (non-perpendicular) to the catheter axis and filled with a thermoplastic elastomer (such as polyurethane, nylon elastomer, etc.). This structure is equivalent to introducing a controllable deformation area on a high-strength rigid substrate. When the catheter bends in the blood vessel, the non-perpendicular slit direction helps to more effectively release stress along a specific path, thereby reducing the bending stiffness of this area. The filled thermoplastic elastomer is embedded in the slit to form a connecting structure, providing flexibility. This design, while maintaining the continuity and axial strength of the carbon fiber tube main structure, specifically improves the bending flexibility of the catheter distal end, enabling it to better adapt to the anatomical morphology of tortuous blood vessels. The oblique or spiral arrangement of the slit structure combined with the filled elastomer allows the distal end section to exhibit anisotropic deformation characteristics. When a torsional force is applied to the proximal end, the elastomer filled in the slit area allows a controllable small deformation to occur, which helps to more evenly transmit the torsional force to the distal end, while allowing the distal end to adapt to the natural twisting of the blood vessel. This design improves the torsional followability of the catheter, helping to achieve more accurate steering control in complex blood vessel paths and possibly reducing damage to the blood vessel wall. In addition, the processing technology of carbon fiber tube has advantages in efficiency compared to metal coil or braiding technology, which can reduce manufacturing cost and time.

[0008] Further, the thermoplastic elastomer is TPU. TPU can form a more stable and durable flexible connection bridge in the slit, ensuring that the filling body does not easily fall off or fail when the catheter is repeatedly bent and twisted, and maintaining the flexibility and torsional followability of the distal end in the long term, while meeting strict medical material safety standards.

[0009] Further, the elastic modulus of the thermoplastic elastomer is 50-200 MPa. A modulus that is too low (<50 MPaa) can result in insufficient support of the filling body, weakening the local pressure flattening ability of the slit area; a modulus that is too high (>200 MPa) can limit the deformation ability and reduce the flexibility improvement effect.

[0010] Further, the material of the outer tube is selected from at least one of nylon, TPU (thermoplastic polyurethane elastomer), and PEBAX (polyether block polyamide). These materials give the catheter outer layer good biocompatibility, wear resistance (reducing friction damage during pushing), and moderate flexibility.

[0011] Further, the material of the inner layer tube is at least one of PTFE, PE and FEP. The inner layer tube adopts PTFE (polytetrafluoroethylene), PE (polyethylene) or FEP (fluorinated ethylene propylene) and the like, which has very low surface friction coefficient and excellent chemical inertness.

[0012] Further, the carbon fiber tube is plated with a developing layer. The carbon fiber tube is plated with a developing layer (such as gold, platinum-iridium alloy, barium sulfate composite coating and the like), which solves the key problem of poor X-ray developing property of the carbon fiber material.

[0013] Further, the width of the slit is 0.3-1.5 mm. If the width is too small (<0.3 mm), the thermoplastic elastomer may be difficult to fill, the filling amount may be insufficient or the filling may be not real, which affects the effect and stability of the flexible connecting bridge; if the width is too large (>1.5 mm), the local strength of the carbon fiber tube in the area may be excessively weakened, which increases the risk of structural failure under high pressure suction or complex operation.

[0014] Further, the surface of the proximal end section is provided with a notch. The surface of the proximal end section (connected with the handle) of the carbon fiber tube is provided with a notch, which mainly enhances the bonding strength and anti-kinking ability of the key connection area. Further, the notch is a cross-shaped notch.

[0015] The second aspect of the present application provides a preparation method of the above-mentioned carbon fiber framework medical catheter, which comprises the following steps: forming the slit on the distal end section of the carbon fiber tube by laser cutting, sleeving the outer layer tube on the surface of the carbon fiber tube, the inner surface of the outer layer tube being a thermoplastic elastomer layer, the softening temperature T1 of the thermoplastic elastomer layer being 20-50℃ lower than the softening temperature T2 of the outer layer tube, heating the outer layer tube to a temperature T3, wherein T1

[0016] The preparation method realizes the thermal shrinkage of the outer layer tube under the condition of strictly controlling the heating temperature (T1

[0017] Further, the thermoplastic elastomer of the inner surface of the outer tube has a thickness of 50-100 μm. Defining the thickness of the thermoplastic elastomer to be 50-100 μm ensures that there is sufficient amount of the melted elastomer to completely fill the gap of the slit (less than 50 μm is likely to be insufficiently filled), while avoiding the risk of overflow of the melt due to excessive thickness (more than 100 μm), thus ensuring that the final outer tube can be uniformly and tightly attached to the carbon fiber tube body, accurately maintaining the structure size and performance of the catheter. DETAILED DESCRIPTION

[0018] For the purposes of this application, a more complete description of the application will be presented below. The application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the application more thorough and comprehensive.

[0019] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited. In the description of the application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise specifically limited.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the specification of the application herein is only for the purpose of describing specific embodiments and is not intended to limit the application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0021] In the present application, the technical features described in an open manner include both closed technical solutions consisting of listed features and open technical solutions containing listed features.

[0022] In the present application, when referring to a numerical interval, the above numerical interval is considered to be continuous and includes the minimum value and the maximum value of the range, and each value between the minimum value and the maximum value, unless otherwise specified. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges falling within the range.

[0023] The percentage content referred to in the present application, if not otherwise specified, means mass percentage for solid-liquid mixing and solid-solid mixing, and volume percentage for liquid-liquid mixing.

[0024] The percentage concentration referred to in the present application, if not otherwise specified, means final concentration. The final concentration refers to the proportion of the added component in the system after the component is added.

[0025] The temperature parameter in the present application, if not otherwise specified, allows both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument.

[0026] The "particles" referred to in the present application, or the substances with defined particle size distribution, are not necessarily spherical in shape, but can also be irregular, and can be primary particles or secondary particles. The particle size of irregular particles is calculated as the average of the maximum diameter and the minimum diameter.

[0027] Example 1: The present example provides a preparation method of a carbon fiber framework medical catheter.

[0028] Carbon fiber tube processing: laser cutting of distal end spiral slits (width 0.5 mm, pitch 2 mm), laser engraving of cross-shaped notches at the proximal end, vacuum plating of platinum-iridium alloy development layer on the surface.

[0029] Medical catheter assembly: insert the PTFE inner tube into the carbon fiber tube lumen and heat press to shape. The outer tube is prepared by a three-layer co-extrusion process, with PEBAX 2533 (softening point T2 = 131℃) of 300 μm thickness as the outer layer and TPU layer (softening point T1 = 90℃, elastic modulus 50 MPaa) of 100 μm as the inner layer. The outer tube is sleeved outside the carbon fiber tube, heated to a temperature T3 = 100℃, and cooled to obtain the carbon fiber framework medical catheter, and then the proximal end of the carbon fiber tube is connected with the handle.

[0030] Example 2: The present example provides a preparation method of a carbon fiber framework medical catheter.

[0031] Carbon fiber tube processing: laser cutting of distal end spiral slits (width 0.5 mm, pitch 2 mm), laser engraving of cross-shaped notches at the proximal end, vacuum plating of platinum-iridium alloy development layer on the surface.

[0032] Medical catheter assembly: FEP inner tube is inserted into the inner cavity of the carbon fiber tube, and is heat-pressed and shaped. The outer tube is prepared by a three-layer co-extrusion process, the outer layer is PEBAX 2533 with a thickness of 300 pm (softening point T2=131 °C), and the inner layer is a TPU layer with a thickness of 100 pm (softening point T1=100 °C, elastic modulus 100 MPa). The outer tube is sleeved outside the carbon fiber tube, heated to a temperature T3=115 °C, and then cooled to obtain a carbon fiber skeleton medical catheter, and then the proximal end of the carbon fiber tube is connected with a handle.

[0033] Example 3: The present embodiment provides a method for preparing a carbon fiber skeleton medical catheter.

[0034] Carbon fiber tube processing: laser cutting of a spiral slit at the distal end (width 1.5 mm, pitch 2 mm), laser engraving of a cross-shaped notch at the proximal end, and vacuum plating of a platinum-iridium alloy developing layer on the surface.

[0035] Medical catheter assembly: PTFE inner tube is inserted into the inner cavity of the carbon fiber tube, and is heat-pressed and shaped. The outer tube is prepared by a three-layer co-extrusion process, the outer layer is PEBAX 2533 with a thickness of 300 pm (softening point T2=131 °C), and the inner layer is a TPU layer with a thickness of 100 pm (softening point T1=100 °C, elastic modulus 100 MPa). The outer tube is sleeved outside the carbon fiber tube, heated to a temperature T3=115 °C, and then cooled to obtain a carbon fiber skeleton medical catheter, and then the proximal end of the carbon fiber tube is connected with a handle.

[0036] Example 4: The present embodiment provides a method for preparing a carbon fiber skeleton medical catheter.

[0037] Carbon fiber tube processing: laser cutting of a spiral slit at the distal end (width 1.5 mm, pitch 2 mm), laser engraving of a cross-shaped notch at the proximal end, and vacuum plating of a platinum-iridium alloy developing layer on the surface.

[0038] Medical catheter assembly: PTFE inner tube is inserted into the inner cavity of the carbon fiber tube, and is heat-pressed and shaped. The outer tube is prepared by a three-layer co-extrusion process, the outer layer is PEBAX 2533 with a thickness of 300 pm (softening point T2=131 °C), and the inner layer is a TPU layer with a thickness of 100 pm (softening point T1=100 °C, elastic modulus 100 MPa). The outer tube is sleeved outside the carbon fiber tube, heated to a temperature T3=115 °C, and then cooled to obtain a carbon fiber skeleton medical catheter, and then the proximal end of the carbon fiber tube is connected with a handle.

[0039] Example 5: The present embodiment provides a method for preparing a carbon fiber skeleton medical catheter.

[0040] Carbon fiber tube processing: laser cutting of a spiral slit at the distal end (width 1.5 mm, pitch 2 mm), laser engraving of a cross-shaped notch at the proximal end, and vacuum plating of a platinum-iridium alloy developing layer on the surface.

[0041] Medical catheter assembly: PTFE inner tube is inserted into the inner cavity of the carbon fiber tube, and hot-pressed to shape. The outer tube is prepared by a three-layer co-extrusion process, the outer layer is PEBAX 2533 with a thickness of 300 pm (softening point T2 = 131 °C), and the inner layer is a TPU layer with a thickness of 100 pm (softening point T1 = 90 °C, elastic modulus 50 MPa). The outer tube is sleeved outside the carbon fiber tube, heated to a temperature T3 = 120 °C, and cooled to obtain a carbon fiber skeleton medical catheter, and then the proximal end of the carbon fiber tube is connected with a handle.

[0042] Comparative Example 1: The present comparative example provides a preparation method of a carbon fiber skeleton medical catheter.

[0043] Carbon fiber tube processing: laser cutting of a spiral slit at the distal end (width 0.5 mm, pitch 2 mm), laser engraving of a cross-shaped notch at the proximal end, and vacuum plating of a platinum-iridium alloy developing layer on the surface.

[0044] Medical catheter assembly: PTFE inner tube is inserted into the inner cavity of the carbon fiber tube, and hot-pressed to shape. The outer tube (PEBAX 2533 with a thickness of 300 pm) is sleeved outside the carbon fiber tube, heated to a temperature T3 = 100 °C, and cooled to obtain a carbon fiber skeleton medical catheter, and then the proximal end of the carbon fiber tube is connected with a handle.

[0045] Comparative Example 2: The present comparative example provides a preparation method of a carbon fiber skeleton medical catheter.

[0046] Carbon fiber tube processing: laser cutting of a spiral slit at the distal end (width 0.15 mm, pitch 2 mm), laser engraving of a cross-shaped notch at the proximal end, and vacuum plating of a platinum-iridium alloy developing layer on the surface.

[0047] Medical catheter assembly: PTFE inner tube is inserted into the inner cavity of the carbon fiber tube, and hot-pressed to shape. The outer tube is prepared by a three-layer co-extrusion process, the outer layer is PEBAX 2533 with a thickness of 300 pm (softening point T2 = 131 °C), and the inner layer is a TPU layer with a thickness of 100 pm (softening point T1 = 90 °C, elastic modulus 50 MPa). The outer tube is sleeved outside the carbon fiber tube, heated to a temperature T3 = 100 °C, and cooled to obtain a carbon fiber skeleton medical catheter, and then the proximal end of the carbon fiber tube is connected with a handle.

[0048] The axial tensile strength and the head end hardness of the medical catheters of the above examples and comparative examples are tested, and the test results are shown in Table 1.

[0049] The test method of the axial tensile strength is as follows: a universal material testing machine is used, clamped at the distal end 100 mm of the medical catheter, stretched at a rate of 200 mm / min, and the maximum tension before the catheter breaks (unit: N) is recorded, and the average value of 5 groups of samples is taken.

[0050] The test method for the head end stiffness is as follows: cut the catheter distal end (including the filled slit section) into 5 mm long samples, use a micro force testing machine, press into 0.5 mm depth with 0.5 mm diameter indenter at 0.1 mm / s speed, record the maximum force value (unit: g), take the average value of 5 groups of samples.

[0051] Table 1: Test results of axial tensile strength and head end stiffness of examples and comparative examples.

[0052] According to the data in Table 1, the performance of Examples 1-5 is better than that of Comparative Examples 1-2, because the carbon fiber skeleton medical catheter uses carbon fiber tube to replace traditional metal material as the intermediate reinforcing layer, and combines with the specific angle slit structure of the distal end filled with thermoplastic elastomer. Compared with metal materials, carbon fiber has higher axial tensile strength and excellent fatigue resistance, which helps to reduce the risk of fracture of the distal end of the catheter due to tension during the withdrawal operation, thereby reducing the possibility of complications such as thrombosis or surgical removal of the broken free section. The high specific modulus property of carbon fiber enables it to provide sufficient radial support force while achieving a thinner wall thickness, increasing the effective lumen of the catheter, which is beneficial to improving the pumping efficiency. The slit on the distal end section of the carbon fiber tube is processed at an angle (non-perpendicular) to the catheter axis, and is filled with thermoplastic elastomer (such as polyurethane, nylon elastomer, etc.), which is equivalent to introducing a controllable deformation area on the high-strength rigid substrate. When the catheter bends in the blood vessel, the non-perpendicular direction of the slit helps to more effectively release stress along a specific path, thereby reducing the bending stiffness of the region. The filled thermoplastic elastomer is embedded in the slit to form a connecting structure, which reduces the head end stiffness while maintaining the continuity and axial strength of the carbon fiber tube main structure, thereby reducing the risk of blood vessel perforation. The oblique or spiral arrangement of the slit structure combined with the filled elastomer makes the distal end section exhibit anisotropic deformation characteristics. When a torsional force is applied to the proximal end, the elastomer filled in the slit area allows a controllable slight deformation, which helps to more evenly transmit the torsional force to the distal end, while allowing the distal end to adapt to the natural twist of the blood vessel. Comparative Example 1 does not use TPU to fill the slit, and the slit is prone to form stress concentration notches, resulting in a decrease in mechanical properties; Comparative Example 2 uses a slit that is too narrow, which may make it difficult for TPU to fill the slit, and the effect of the present scheme cannot be achieved, and the too narrow slit also reduces the axial tensile properties of the catheter.

[0053] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0054] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A carbon fiber skeleton medical catheter, characterized in that: The invention comprises a hollow catheter body and a handle, wherein the catheter body comprises an inner tube, an intermediate tube and an outer tube, wherein the intermediate tube is a carbon fiber tube, and comprises a proximal section connected to the handle and a distal section on the other side, wherein the distal section is provided with a plurality of slits connected to the inner cavity of the catheter, wherein the extension direction of the slits is set at an angle to the axial direction of the catheter, and the slits are filled with a thermoplastic elastomer.

2. The carbon fiber skeleton medical catheter according to claim 1, characterized in that: The thermoplastic elastomer is TPU.

3. The carbon fiber skeleton medical catheter according to claim 1, characterized in that: The elastic modulus of the thermoplastic elastomer is 50-200 MPa.

4. The carbon fiber skeleton medical catheter according to claim 1, characterized in that: The material of the outer tube is selected from at least one of nylon, TPU and PEBAX.

5. The carbon fiber skeleton medical catheter according to claim 1, characterized in that: The material of the inner tube is at least one of PTFE, PE and FEP.

6. The carbon fiber skeleton medical catheter according to claim 1, characterized in that: The surface of the carbon fiber tube is coated with a developing layer.

7. The carbon fiber skeleton medical catheter according to claim 1, characterized in that: The width of the slit is 0.3-1.5 mm.

8. The carbon fiber skeleton medical catheter according to claim 1, characterized in that: The surface of the proximal section is provided with notches.

9. The method for preparing a carbon fiber skeleton medical catheter according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: forming the slit at the distal end of the carbon fiber tube by laser cutting, sleeve- ing an outer tube on the surface of the carbon fiber tube, wherein the inner surface of the outer tube is a thermoplastic elastomer layer, the softening temperature T1 of the thermoplastic elastomer layer is 20-50°C lower than the softening temperature T2 of the outer tube, and heating the outer tube to a temperature T3, wherein T1 < T3 < T2, so that the outer tube shrinks and adheres to the surface of the carbon fiber tube.

10. The preparation method according to claim 9, characterized in that The thickness of the thermoplastic elastomer on the inner surface of the outer tube is 50-100 μm.

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