Outer hose of medical composite catheter and preparation method of outer hose

Abstract

The invention discloses a preparation method of an outer hose of a medical composite catheter, which comprises the following steps: mixing and drying a thermoplastic polymer and a modifier in a weight ratio range of 97: 3-99.5: 0.5 to obtain a mixture; melting and pelletizing the mixture to obtain blend particles; and carrying out extrusion molding on the blend particles to obtain the outer hose. According to the embodiment of the invention, the thermoplastic polymer is subjected to slipping modification by using the modifier with the weight ratio of 0.5-2%, and the thermoplastic polymer and the modifier are sequentially subjected to mixing drying, melting pelletizing and extrusion molding according to the proportion range, so that the outer hose of the medical composite catheter, which is uniform in appearance, smooth and fine in surface and wear-resistant, is obtained; the outer hose manufactured through the method has good anti-blocking performance, resistance generated by friction in the use process of the catheter is effectively reduced, inconvenience and risks caused by blocking are avoided, insertion and positioning are convenient, and the use safety and reliability of the medical composite catheter are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of medical materials, in particular to an outer hose of a medical composite catheter and a preparation method thereof. Background Art

[0002] In modern medicine, composite catheters play an important role in the treatment of urology and vascular surgery. In minimally invasive medical fields such as urology and vascular surgery, composite catheters are widely used in treatment and diagnosis. When these catheters enter the human blood vessels or urinary system, they often need to pass through curved or twisted areas of the tube affected by lesions. These lesions not only increase the difficulty of catheter passage, but may also affect the positioning and function of the catheter.

[0003] Therefore, in order to ensure smooth passage through these complex lesions, the outer hose of the composite catheter must be designed to be sufficiently flexible to avoid damage to the tissue while ensuring the operability and therapeutic effect of the catheter. In the prior art, the outer hose of the composite catheter is usually made of medical polymer materials through a conventional extrusion molding process. The hardness of this outer hose is relatively low to ensure that the catheter is soft and flexible.

[0004] However, although this material and molding method can meet the basic softness requirements, its mechanical properties and surface characteristics have certain limitations, which affect the actual application effect of the catheter. The existing hose is easy to adhere to itself or other pipes due to its thin wall and low hardness, making it difficult to separate. Even in the case of forced separation, the hose material will be damaged. This feature brings great inconvenience in packaging, transportation, storage and processing, which not only increases the difficulty of operation, but also seriously reduces the qualified rate of the product, affecting the application effect and service life of the composite catheter. Summary of the invention

[0005] The invention provides an outer hose of a medical composite catheter and a preparation method thereof, so as to solve the technical problem that the outer hose of the existing medical composite catheter has high adhesion.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing an outer hose of a medical composite catheter, comprising:

[0007] Mixing and drying a thermoplastic polymer and a modifier to obtain a mixture, wherein a weight ratio of the thermoplastic polymer to the modifier is in the range of 97:3-99.5:0.5;

[0008] Melting and pelletizing the mixture to obtain blend particles;

[0009] The blend particles are extruded to obtain the outer hose.

[0010] Furthermore, after the thermoplastic polymer and the modifier are mixed, the thermoplastic polymer and the modifier are dried under a first vacuum condition at a temperature of 70-80° C. for 6-8 hours, and the vacuum degree of the first vacuum condition is 0.02-0.05 Mpa.

[0011] Furthermore, the weight ratio of the thermoplastic polymer to the modifier is in the range of 98.5:1.5-99:1, and the moisture content of the mixture obtained after drying the thermoplastic polymer and the modifier is less than or equal to 0.02%.

[0012] Furthermore, after the thermoplastic polymer and the modifier are dried, the moisture content of the mixture is in the range of 0.005%-0.015%.

[0013] Furthermore, the thermoplastic polymer is one or both of polyether block polyamide and thermoplastic polyurethane.

[0014] Furthermore, the modifier is fatty amide.

[0015] Furthermore, before the blend particles are extruded, the blend particles are melt-extruded into a polymer solution, and then the polymer solution is pulled and cooled to obtain the outer hose.

[0016] Furthermore, the temperature for melt extrusion of the blend particles is 190-200°C, the pressure for extruding the polymer melt is 2-3Mpa, and the temperature for cooling and shaping the polymer melt is 5-10°C.

[0017] Furthermore, when the mixture is melt-pelletized, the mixture is melt-extruded under a second vacuum condition at a temperature of 180-190° C., and the vacuum degree of the second vacuum condition is less than or equal to 40 mbar.

[0018] On the other hand, the present invention also provides an outer hose of a medical composite catheter, which is prepared by any of the methods described above.

[0019] Compared with the prior art, the outer hose of a medical composite catheter and the preparation method thereof according to the embodiment of the present invention have the following beneficial effects:

[0020] In the embodiment of the present invention, a thermoplastic polymer is modified by using a modifier with a weight ratio of 0.5%-3%, and the thermoplastic polymer and the modifier are mixed and dried in a proportion range, melt-cut and extruded to obtain an outer hose of a medical composite catheter with a symmetrical appearance, smooth and delicate surface and wear resistance, so that the outer hose prepared by the method has good anti-adhesion, effectively reduces the resistance caused by friction during the use of the catheter, avoids the inconvenience and risk caused by adhesion, is easy to insert and position, and enhances the wear resistance and chemical corrosion resistance, effectively improving the safety and reliability of the use of the medical composite catheter. This modification method not only improves the operating performance of the medical composite catheter, but also effectively reduces the adhesion phenomenon during packaging, transportation and use, ensuring the smooth use and operational reliability of the catheter in all links.

[0021] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. DETAILED DESCRIPTION

[0022] The following will be combined with 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.

[0023] In the description of the present invention, it should be noted that directional words, such as the terms "middle", "upper", "lower", "inside", "outside", etc., indicating directions and positional relationships are based on the directions or positional relationships shown. They 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 operated in a specific orientation, and cannot be understood as limiting the specific protection scope of the present invention.

[0024] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. Therefore, the definition of "first" and "second" features can explicitly or implicitly include one or more of the features. In the description of the present invention, "at least" means one or more, unless otherwise clearly and specifically defined.

[0025] An embodiment of the present invention provides a method for preparing an outer hose of a medical composite catheter, comprising:

[0026] Mixing and drying the thermoplastic polymer and the modifier to obtain a mixture, wherein the weight ratio of the thermoplastic polymer to the modifier is in the range of 97:3-99.5:0.5;

[0027] The mixture is melt-pelletized to obtain blend particles;

[0028] The blend pellets are extruded to obtain an outer hose.

[0029] In the embodiment of the present invention, a thermoplastic polymer is modified by using a modifier with a weight ratio of 0.5%-3%, and the thermoplastic polymer and the modifier are mixed and dried in a proportion range, melt-cut and extruded to obtain an outer hose of a medical composite catheter with a symmetrical appearance, smooth and delicate surface and wear resistance, so that the outer hose prepared by the method has good anti-adhesion, effectively reduces the resistance caused by friction during the use of the catheter, avoids the inconvenience and risk caused by adhesion, is easy to insert and position, and enhances the wear resistance and chemical corrosion resistance, effectively improving the safety and reliability of the use of the medical composite catheter. This modification method not only improves the operating performance of the medical composite catheter, but also effectively reduces the adhesion phenomenon during packaging, transportation and use, ensuring the smooth use and operational reliability of the catheter in all links.

[0030] It should be noted that a composite catheter is a catheter made of multiple layers or multiple materials and is widely used in the medical field. It is usually composed of an inner tube and an outer tube, and each part performs different functions. The design and material selection of the composite catheter are intended to meet the special requirements of medical operations, such as flexibility, wear resistance, and chemical corrosion resistance. In the composite catheter structure, the outer hose is the outermost layer of the catheter. In order to ensure that the composite catheter can pass through complex lesions smoothly during treatment, it is necessary to ensure that the outer hose body is soft and has a smooth surface. The main function of the outer hose is to reduce the friction of the catheter during insertion and positioning, so that it can pass through human tissue smoothly. Prevent adhesion on the outer surface of the catheter during use, packaging and transportation.

[0031] Among them, modifiers are a type of additives used to improve material properties and are widely used in the modification of plastics, rubbers and other polymers. In medical composite catheters, the role of modifiers is to enhance certain physical and chemical properties of the material to meet specific application requirements. In medical catheters, commonly used modifiers include polytetrafluoroethylene (PTFE) powder, silicone, paraffin-based lubricants, antistatic agents, etc. These modifiers are added to the catheter material in appropriate proportions and will not significantly change other properties of the material, but can greatly improve its operating performance and safety of use.

[0032] In an optional embodiment of the present invention, after the thermoplastic polymer and the modifier are mixed, the thermoplastic polymer and the modifier are dried under a first vacuum condition at a temperature of 70-80° C., the drying time is 6-8 hours, and the vacuum degree of the first vacuum condition is 0.02-0.05 MPa.

[0033] Specifically, a high-speed mixer with a rotation speed of 300-500r / min is used to fully mix the thermoplastic polymer (such as polyether block polyamide, thermoplastic polyurethane) with the fatty amide modifier for 1-3min, and then a vacuum dryer is used to dry the mixed product in the high-speed mixer. The drying temperature is 70-80°C. This temperature range can effectively remove the moisture and volatile components in the mixture without damaging the material, avoiding the damage of high temperature to the molecular structure and physical properties of the thermoplastic polymer. The vacuum dryer uses a first vacuum condition with a vacuum degree of 0.02-0.05MPa for drying, reducing oxygen contact and lowering the boiling point of volatiles, which helps to dry quickly. The drying time of 6-8 hours ensures that the modifier is fully penetrated and evenly distributed in the thermoplastic polymer, while completely volatilizing the moisture and trace solvents, and improving the final performance of the material. This vacuum drying process ensures that the fatty amide is evenly distributed in the polymer, avoiding the adverse effects of residual moisture on the material performance. The entire process is carried out under strict aseptic conditions to avoid the introduction of external pollution sources. The method can improve the processing fluidity and slip effect of thermoplastic polymers in subsequent processing, while improving the service life and reliability of the materials.

[0034] In an optional embodiment of the present invention, the weight ratio of the thermoplastic polymer to the modifier is in the range of 98.5:1.5-99:1, and the moisture content of the mixture obtained after drying the thermoplastic polymer and the modifier is in the range of less than or equal to 0.02%.

[0035] Specifically, for the mixing ratio of thermoplastic polymer and modifier, the preferred weight ratio range may be 98.5:1.5-99:1. The amount of modifier within this ratio range achieves an ideal balance between improving material properties (such as anti-adhesion, wear resistance, etc.) and maintaining the basic properties of thermoplastic polymer. After drying, the moisture content of the mixture is less than or equal to the standard of 0.02% by strictly controlling the conditions. The low moisture content reduces the potential degradation risk of moisture to thermoplastic polymers, especially during high-temperature melt processing, to avoid performance degradation caused by hydrolysis. In addition, the mixture with a lower moisture content is easier to flow evenly during extrusion or injection molding, which can avoid water vapor from generating bubbles or pores at high temperatures, ensuring the density and surface finish of the product.

[0036] In an optional embodiment of the present invention, the moisture content of the mixture obtained after drying the thermoplastic polymer and the modifier is in the range of 0.005%-0.015%.

[0037] Specifically, preferably, the mixture of the thermoplastic polymer and the modifier is dried to control the moisture content of the mixture within the range of 0.005%-0.015%. The moisture content within this range can not only ensure the smooth progress of the processing process, but also effectively prevent the problems of bubbles and structural unevenness during the melting process caused by residual moisture. Keeping the moisture content at this low level can significantly improve the surface smoothness and structural density of the outer hose, ensuring that the finished product has higher anti-adhesion and durability. In addition, strict moisture control can also reduce the risk of aging of the material during processing and storage, thereby improving the overall quality and service life of the medical composite catheter.

[0038] In an optional embodiment of the present invention, the thermoplastic polymer is one or both of polyether block polyamide and thermoplastic polyurethane.

[0039] Specifically, in this material combination, polyether block polyamide and thermoplastic polyurethane (TPU) are both common thermoplastic polymers with flexibility, wear resistance and good biocompatibility, which are very suitable for use in medical catheters and other scenarios. Among them, polyether block polyamide is a thermoplastic elastomer with high elasticity and good flexibility, composed of polyamide (PA) and polyether (PE) segments, with high impact resistance and wear resistance, both hardness and elasticity, suitable for long-term use, and used in products with high requirements for biocompatibility and chemical resistance in the medical and industrial fields; thermoplastic polyurethane (TPU) is a thermoplastic elastomer synthesized from diisocyanates (such as MDI, TDI), polyether or polyester polyols and chain extenders. It is a thermoplastic material with both elasticity and strength. It has a variety of excellent properties due to its reversible soft and hard segment structure. It is widely used in catheter outer layer materials due to its excellent wear resistance and tear resistance.

[0040] In an optional embodiment of the present invention, the modifier is a fatty amide.

[0041] Specifically, fatty amides (FA) are a class of compounds generated by the reaction of fatty acids and amines. Common fatty amides include oleamide, erucamide, and stearamide. The fatty acid chains in the structure of these compounds give them hydrophobicity, while the amine structure provides a certain polarity, which makes them show excellent modification effects in a variety of materials. After the fatty amide molecules migrate to the surface of the material, they can reduce the direct contact between the surfaces of the materials and reduce adhesion, especially effectively preventing the adhesion of plastic products during packaging and transportation. Fatty amide molecules can form a low-friction film on the surface of the material to reduce the friction between the materials, so fatty amides are added to polymers as lubricants to improve surface smoothness.

[0042] In the outer hose of the medical composite catheter prepared by the method, the fatty amide can be selected from oleamide, erucamide and stearamide, and the modifier is in powder or granular form, so as to facilitate better mixing and dispersion during the production process, thereby improving the softness and applicability of the catheter. It should be emphasized that the types of fatty amides described in the present invention are only examples of the specific embodiments of the present application, and are intended to provide an example of implementing the technology, and do not constitute any limitation to the present invention. In fact, the present invention can adopt various suitable fatty amides according to different application requirements and technical environments to achieve optimal performance. Therefore, the types of fatty amides mentioned in the examples are only exemplary, and other types of fatty amides that may be applicable are not excluded.

[0043] In an optional embodiment of the present invention, before the blend particles are extruded, the blend particles are melt-extruded into a polymer solution, and the polymer solution is then pulled and cooled to obtain an outer hose.

[0044] Specifically, a single screw extruder with a screw diameter of 35-45 mm, a screw aspect ratio of 1:30, and a screw speed of 200-300 rpm is used to melt-extrude the blend particles into a polymer solution. The main process of the outer hose melt extrusion molding is as follows: In the melt extrusion stage, the single screw extruder is used to heat the pre-mixed particles to a molten state to form a polymer solution. Through the rotation of the screw, the material is effectively pushed in the barrel and undergoes shearing and mixing, thereby ensuring that the modifier (such as fatty amide) is evenly dispersed in the polymer matrix; in the traction stage, the polymer solution flows out of the single screw extruder, and the polymer solution is stretched by the traction device at a traction speed of 5-10 m / min, which helps to control the diameter, wall thickness and shape of the outer hose and ensure that the final product meets the design requirements; in the cooling molding stage, after traction, the polymer solution is cooled by an optional water tank. This process is to immerse the hose in constant temperature water to quickly cool it to a solid state. The rapidity of cooling can effectively prevent hose surface defects such as bubbles or uneven solidification, ensuring a smooth surface and excellent physical properties of the outer hose.

[0045] After cooling, the polymer melt can be cut according to the needs, and the cutting process can be cut by a roller cutter with a cutting speed of 10-15m / min to obtain the finished outer hose of the required length. Through this series of steps, from melt extrusion, traction to water tank cooling, it can effectively ensure that the final medical composite catheter outer hose has excellent performance and quality and meets the high standards of medical application requirements. Each link in this process needs to be precisely controlled to ensure the consistency and reliability of the final product.

[0046] It should be noted that in the design of a single-screw extruder, the extrusion die is a crucial component, which directly affects the shape and size of the final product. The main structure of the extrusion die includes the die and the core die set in the die. The die is the outlet part of the extruder, which is responsible for pushing the molten polymer out of the extruder and forming the required cross-sectional shape. The core die is nested in the die and is mainly used to determine the inner diameter of the extruded product. The design of the core die is crucial to ensure the smoothness of the inner cavity of the catheter and the uniformity of the diameter. The straight shaping section refers to a straight section with a certain length inside the die, which allows the molten polymer to be fully shaped and cooled during the extrusion process. The length of the straight shaping section of the die and the core die is greater than or equal to 15mm. This design ensures that when the molten polymer flows out of the die, the material can be fully flattened and cooled within a certain distance, thereby forming a uniform product structure and avoiding the formation of irregular edges or surface defects.

[0047] In an optional embodiment of the present invention, the temperature for melt extrusion of the blend particles is 190-200°C, the pressure of the extruded polymer melt is 2-3 MPa, and the temperature for cooling and shaping the polymer melt is 5-10°C.

[0048] Specifically, in this process, the melt extrusion temperature of the blend particles should be controlled at 190-200°C to ensure that the material has good fluidity in the molten state and to avoid thermal degradation of the polymer. During the extrusion process, the pressure of the polymer melt needs to be maintained at 2-3MPa to ensure the stability of the extrusion flow rate and molding quality. In addition, in order to maintain a good structure of the polymer after extrusion molding, the melt needs to be cooled quickly, and the temperature of the water tank during cooling and shaping should be controlled at 5-10°C, which can effectively reduce its temperature, promote the solidification of the polymer, stabilize the shape and size of the product, and reduce deformation caused by shrinkage to ensure that the product surface is smooth and maintain the necessary physical properties. The extrusion temperature of a single-screw extruder needs to be strictly controlled between 190-200°C to ensure that the material flows stably in the molten state, laying the foundation for subsequent processing.

[0049] In an optional embodiment of the present invention, when the mixture is melt-pelletized, the mixture is melt-extruded under a second vacuum condition at a temperature of 180-190° C., and the vacuum degree of the second vacuum condition is less than or equal to 40 mbar.

[0050] Specifically, when the mixture is melt pelletized, a co-rotating twin-screw extruder with an aspect ratio of 1:30-1:45 and a screw speed of 200-400rpm can be used to melt extrude the mixture, and the melt extrusion conditions are as follows: the extrusion temperature of the co-rotating twin-screw extruder is 180-190°C, and the vacuum degree of the co-rotating twin-screw extruder is less than or equal to 40mbar. 180-190°C is sufficient to melt thermoplastic polymers (such as PEBA, TPU or nylon 12), while at the same time making the fatty amide modifier evenly distributed in the melt, avoiding thermal damage to the material caused by excessive temperature, and this temperature can ensure the structural stability and surface quality of the final product. The vacuum degree of the second vacuum condition is less than or equal to 40mbar. Extrusion under vacuum conditions can effectively remove moisture and volatiles generated during the melting process, avoid the formation of bubbles or pores, and improve the density and surface finish of the material.

[0051] It should be noted that the co-rotating twin-screw extruder is a processing equipment used for efficient mixing and plasticizing of materials. It is widely used in the fields of plastics, rubber, food and medicine, and is particularly suitable for material modification or blending processes that require uniform dispersion and fine mixing. The co-rotating twin-screw extruder has two parallel screws that rotate in the same direction. The two screws are usually longer, and the thread design allows them to mesh with each other when rotating.

[0052] The performance test of the outer hose of the medical composite catheter obtained in the above embodiment was carried out, and the results are as follows:

[0053] Table 1 Mechanical properties of outer hoses obtained using different weight ratios of polyether block polyamide PEBAX2533 (hardness 75A) and fatty amide (FA)

[0054]

[0055] Table 1 shows the mechanical properties test results of the outer hose of the medical composite catheter obtained by mixing polyether block polyamide PEBAX2533 (hardness 75A) and fatty amide (FA) produced by Arkema in different weight ratios and then preparing it by the above method. It can be seen from Table 1 that with the increase of the proportion of fatty amide (FA) in the mixture, the dynamic friction coefficient and static friction coefficient of the outer hose show an overall downward trend, and then tend to be flat. When the proportion of fatty amide (FA) is 1% and 1.5%, the dynamic friction coefficient and static friction are significantly reduced. When the proportion of fatty amide (FA) exceeds 1.5%, the friction coefficient remains unchanged even if the proportion increases. This shows that the addition of a considerable proportion of fatty amide (FA) can effectively improve the sliding performance of the material, and after adding fatty amide (FA) to a certain extent, even if more proportion of fatty amide (FA) is added, the friction performance of the material is no longer affected.

[0056] Table 2 Mechanical properties of outer hoses obtained using different weight ratios of thermoplastic polyurethane TT-1074A (hardness 75A) and fatty amide (FA)

[0057]

[0058]

[0059] Table 2 shows the mechanical properties test results of the outer hose of the medical composite catheter obtained by mixing thermoplastic polyurethane TT-1074A (hardness 75A) produced by Lubrizol and fatty amide (FA) in different weight ratios and then preparing the above method. It can be seen from Table 2 that with the increase of the proportion of fatty amide (FA) in the mixture, the dynamic friction coefficient and static friction coefficient of the outer hose also show a downward trend as a whole, and then tend to be flat. When the proportion of fatty amide (FA) is 1% and 1.5%, the dynamic friction coefficient and static friction are significantly reduced. When the proportion of fatty amide (FA) exceeds 1.5%, the friction coefficient remains unchanged even if the proportion increases. Similarly, this shows that the addition of a considerable proportion of fatty amide (FA) can effectively improve the sliding performance of the material, and after adding fatty amide (FA) to a certain extent, even if more fatty amide (FA) is added, the friction performance of the material is no longer affected.

[0060] Based on the test data of Table 1 and Table 2, it can be analyzed that in the two materials, the friction coefficient decreases most significantly when the fatty amide (FA) content reaches 1%-1.5%. When the FA ratio exceeds 1.5%, the friction coefficient tends to be stable, and further increasing the FA ratio will no longer significantly improve the friction performance. Even if more fatty amide (FA) is added, the friction performance of the material is no longer greatly affected. Therefore, the addition of fatty amide (FA) in the modifier can significantly reduce the friction coefficient of the outer hose of the medical composite catheter, and the weight ratio of the thermoplastic polymer to the modifier is in the range of 97:3-99.5:0.5, and more preferably 98.5:1.5-99:1.

[0061] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an outer hose of a medical composite catheter, characterized in that: include: Mixing and drying a thermoplastic polymer and a modifier to obtain a mixture, wherein a weight ratio of the thermoplastic polymer to the modifier is in the range of 97:3-99.5:0.5; Melting and pelletizing the mixture to obtain blend particles; The blend particles are extruded to obtain the outer hose.

2. The method for preparing the outer hose of the medical composite catheter according to claim 1, characterized in that: After the thermoplastic polymer and the modifier are mixed, the thermoplastic polymer and the modifier are dried under a first vacuum condition at a temperature of 70-80° C. for 6-8 hours, and the vacuum degree of the first vacuum condition is 0.02-0.05 Mpa.

3. The method for preparing the outer hose of the medical composite catheter according to claim 2, characterized in that: The weight ratio of the thermoplastic polymer to the modifier is in the range of 98.5:1.5-99:1, and the moisture content of the mixture obtained by drying the thermoplastic polymer and the modifier is less than or equal to 0.02%.

4. The method for preparing the outer hose of the medical composite catheter according to claim 3, characterized in that: The moisture content of the mixture obtained by drying the thermoplastic polymer and the modifier is in the range of 0.005% to 0.015%.

5. The method for preparing the outer hose of the medical composite catheter according to claim 1, characterized in that: The thermoplastic polymer is one or both of polyether block polyamide and thermoplastic polyurethane.

6. The method for preparing the outer hose of the medical composite catheter according to claim 1, characterized in that: The modifier is fatty amide.

7. The method for preparing the outer hose of the medical composite catheter according to claim 1, characterized in that: Before the blend particles are extruded, the blend particles are melt-extruded into a polymer solution, and then the polymer solution is pulled and cooled to obtain the outer hose.

8. The method for preparing the outer hose of the medical composite catheter according to claim 7, characterized in that: The temperature for melt extrusion of the blend particles is 190-200°C, the pressure for extruding the polymer melt is 2-3 MPa, and the temperature for cooling and shaping the polymer melt is 5-10°C.

9. The method for preparing the outer hose of the medical composite catheter according to claim 1, characterized in that: When the mixture is melt-pelletized, the mixture is melt-extruded under a second vacuum condition at a temperature of 180-190° C., and the vacuum degree of the second vacuum condition is less than or equal to 40 mbar.

10. An outer hose of a medical composite catheter, characterized in that: The method comprising preparing the product according to any one of claims 1 to 9.

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