CN117656359A - Preparation method of radial catheter, coating die and radial catheter - Google Patents

Abstract

The invention provides a radial catheter preparation method, a coating die and a radial catheter, wherein the radial catheter preparation method comprises the following steps: providing a tubular middle layer; placing an intermediate layer in a cavity of a coating die to form an outer layer cavity positioned at the periphery of the intermediate layer and an inner layer cavity positioned at the inner periphery of the intermediate layer, wherein a penetrating part of the intermediate layer is communicated with the outer layer cavity and the inner layer cavity; injecting a polymer solution into the cavity, and curing after the injection is finished; the wall thickness of the radial catheter can be reduced on the basis of maintaining the interventional performance of the radial catheter, and the problem of loose adhesion between the high polymer solution and the middle layer is avoided; in addition, the outer surface of the formed transcatheter tube is smoother, and the stability of the transcatheter tube is improved.

Description

Preparation method of radial catheter, coating die and radial catheter

Technical Field

The invention relates to the technical field of medical treatment, in particular to a preparation method of a radial catheter, a coating die for preparing the radial catheter and the radial catheter.

Background

The radial catheter for interventional therapy is generally a composite structure comprising an outer layer made of polymer, an intermediate layer made of metal and an inner layer made of polymer from outside to inside. The use of an intermediate layer with high mechanical properties provides the radial catheter with pushability and compliance to meet the requirements of interventional procedures.

The intermediate layer of metal generally comprises a braided tube or coil made of wire braided or wound or a hypotube made of cut metal tubing. The hypotube forms a regular penetrating part through laser engraving, a maximum bending angle can be limited, accurate control of the maximum bending angle of the controllable bent radial catheter can be realized, performances such as bending resistance, pushing and torque can be provided, in addition, thinner wall thickness can be realized to achieve higher performance, namely, larger outer diameter can be realized while higher compatibility is brought by larger inner diameter, and damage to blood vessels can be reduced.

Current radial catheter processing methods generally involve threading a tubular inner layer into a tubular middle layer and then hot-melting an outer layer tube onto the outer periphery of the middle layer to form the outer layer. But this brings about the following problems: 1) Gaps between the inner layer and the middle layer can cause the increase of the whole wall thickness of the radial catheter; 2) When the middle layer is a hypotube, the special groove-shaped penetrating part of the hypotube can cause the inner and outer layer pipes of the penetrating part to be sunken in the process of fusing the outer layer pipe, so that the outer surface of the radial catheter is uneven, and a blood vessel is hung; 3) The penetrating part in the middle layer is smaller, and the outer layer is difficult to flow into the middle layer to be bonded with the inner layer in the process of fusing the outer layer pipe into the narrow penetrating part, so that the stability of the radial catheter is reduced; 4) The hardness mutation of the existing outer layer at the material junction easily occurs, and the pushing effect is affected.

Disclosure of Invention

The invention aims to provide a preparation method of a transcatheter, a coating die for preparing the transcatheter and the transcatheter.

In order to achieve the above object, the present invention provides a method for preparing a radial catheter, comprising the steps of:

providing a tubular middle layer, wherein the pipe wall of the middle layer is provided with a penetrating part which is communicated with the inside and the outside of the middle layer along the radial direction of the middle layer;

placing the middle layer in a cavity of a coating die to form an outer layer cavity positioned at the periphery of the middle layer and an inner layer cavity positioned at the inner periphery of the middle layer, wherein the penetrating part is communicated with the outer layer cavity and the inner layer cavity;

injecting a polymer solution into the cavity, curing after the injection is finished, forming an outer layer of the radial catheter by the polymer solution cured in the outer layer cavity, forming an inner layer of the radial catheter by the polymer solution cured in the inner layer cavity, and forming a connecting part for connecting the outer layer and the inner layer by the polymer solution cured in the penetrating part;

and (5) demolding.

As a further improvement of the present invention, "curing after injecting a polymer solution into the cavity" is specifically: and injecting a polymer solution into the outer-layer cavity, wherein the polymer solution in the outer-layer cavity flows into the inner-layer cavity through the penetrating part.

As a further improvement of the present invention, the ultrasonic generator acting on the cavity is started while the polymer solution is injected into the cavity.

As a further improvement of the present invention, the method for preparing the transcatheter catheter further comprises the steps of:

starting a heating assembly to heat the temperature in the cavity of the material to be injected to a first preset temperature and preserving heat until the material injection is finished, wherein the first preset temperature is not lower than the melting point of the polymer material forming the polymer solution to be injected.

As a further improvement of the present invention, "curing after injection end" is specifically: and closing the heating assembly, and starting a water circulation system for cooling the cavity after feeding until the temperature in the cavity is reduced to a second preset temperature, wherein the second preset temperature is lower than the melting point of the high polymer material forming the high polymer solution.

As a further improvement of the invention, the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top, the sub-cavity comprises an outer layer sub-cavity and an inner layer sub-cavity which correspond to the sub-cavity, and the plurality of sections of sub-cavities respectively correspond to a plurality of polymer solutions; and injecting and curing the polymer solution of the corresponding type into the sub-cavity positioned at the lower side of the two adjacent sections of sub-cavities, and then injecting and curing the polymer solution of the corresponding type into the sub-cavity positioned at the upper side.

As a further improvement of the present invention, "after injecting and curing a polymer solution of a corresponding kind into a sub-cavity located at a lower side of two adjacent sub-cavities, injecting and curing a polymer solution of a corresponding kind into a sub-cavity located at an upper side", specifically includes the steps of:

injecting the polymer solution of the corresponding type into the sub-cavity positioned at the lower side until the distance from the liquid level of the polymer solution to the top end of the sub-cavity is 2 mm-3 mm, continuously injecting the polymer solution of the corresponding type into the sub-cavity positioned at the lower side, simultaneously injecting the polymer solution corresponding to the sub-cavity positioned at the upper side into the sub-cavity to form a mixed solution, and ending the injection when the liquid level of the mixed solution exceeds the bottom end of the sub-cavity positioned at the upper side by 2 mm-3 mm, thereby solidifying the polymer solution;

after the polymer solution is solidified, the polymer solution of the corresponding type is injected into the sub-cavity positioned on the upper side and solidified.

As a further improvement of the present invention, the method for preparing the transcatheter catheter further comprises the following steps after the end of the injection and before the solidification: and conveying the polymer solution in the conveying pipeline for conveying the polymer solution to the direction away from the cavity so as to empty the conveying pipeline.

As a further improvement of the invention, the cavity comprises a plurality of sections of sub-cavities which are mutually communicated from bottom to top, the sub-cavity comprises an outer layer sub-cavity and an inner layer sub-cavity which correspond to the sub-cavity, the plurality of sections of sub-cavities respectively correspond to a plurality of polymer solutions, after the polymer solutions of the corresponding types are injected into the sub-cavities positioned at the lower side of the two adjacent sections of sub-cavities and solidified, the polymer solutions of the corresponding types are injected into the sub-cavities positioned at the upper side and solidified; the step of starting the heating assembly to heat the temperature in the cavity to a first preset temperature and preserving heat until the material injection is finished is specifically as follows: and starting a heating assembly corresponding to the sub cavity to be injected so as to heat the temperature of the sub cavity to be injected to a first preset temperature and preserving heat until the injection is finished.

As a further improvement of the invention, the cavity comprises a plurality of sections of sub-cavities which are mutually communicated from bottom to top, the sub-cavity comprises an outer layer sub-cavity and an inner layer sub-cavity which correspond to the sub-cavity, the plurality of sections of sub-cavities respectively correspond to a plurality of polymer solutions, after the polymer solutions of the corresponding types are injected into the sub-cavities positioned at the lower side of the two adjacent sections of sub-cavities and solidified, the polymer solutions of the corresponding types are injected into the sub-cavities positioned at the upper side and solidified; the step of starting the water circulation system for cooling the cavity until the temperature in the cavity is reduced to a second preset temperature is specifically as follows: and starting a water circulation system corresponding to the material-injected sub-cavity to reduce the temperature in the material-injected sub-cavity to a second preset temperature.

As a further improvement of the present invention, the first preset temperature is 15 ℃ to 25 ℃ higher than the melting point of the polymer material forming the polymer solution.

As a further improvement of the present invention, the second preset temperature is 45 ℃ to 55 ℃ lower than the melting point of the polymer material forming the polymer solution.

As a further improvement of the present invention, the polymer material forming the polymer solution includes silicone oil.

As a further improvement of the invention, the intermediate layer is a hypotube.

In order to achieve the above object, the present invention also provides a coating die comprising:

the hot melting assembly comprises a hot melting box for placing a high polymer material and a hot melting heating piece for hot melting the high polymer material into a high polymer solution;

the molding assembly comprises a shell with a mounting cavity for placing a tubular piece to be coated, and a mandrel arranged in the mounting cavity to form a cavity with the cavity wall of the mounting cavity, wherein the mandrel is used for being inserted into the piece to be coated;

the conveying assembly comprises a conveying pipeline communicated with the hot melting box and the cavity and a conveying pump arranged on the conveying pipeline for conveying the polymer solution.

As a further improvement of the invention, the molding assembly further comprises a heating assembly for heating the cavity.

As a further improvement of the invention, the heating component is a heating wire buried in the shell and arranged around the mounting cavity.

As a further improvement of the present invention, the cavity extends in the up-down direction; the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top; the heating components are in one-to-one correspondence with the sub-type cavities.

As a further improvement of the invention, the molding assembly further comprises a water circulation system for cooling the cavity.

As a further improvement of the present invention, the cavity extends in the up-down direction; the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top; the water circulation systems are in one-to-one correspondence with the sub-type cavities.

As a further improvement of the present invention, the cavity extends in the up-down direction; the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top; the hot melting assemblies are in one-to-one correspondence with the sub-type cavities.

As a further improvement of the invention, the coating die comprises a plurality of forming assemblies which are arranged at intervals around the circumference of the hot melting assembly, and a conveying assembly which is respectively communicated with the hot melting assembly and the forming assemblies.

As a further improvement of the invention, the molding assembly further comprises an ultrasonic generator disposed on the housing and disposed proximate the mounting cavity.

As a further improvement of the invention, a plurality of feed inlets communicated with the mounting cavity are penetrated through the shell, the feed inlets are arranged in pairs, and a pair of feed inlets are oppositely arranged in the radial direction of the mounting cavity.

In order to achieve the above-mentioned purpose, the present invention also provides a transcatheter catheter, which is prepared by the above-mentioned method for preparing a transcatheter catheter; or the radial catheter is prepared by adopting the coating die.

In order to achieve the above object, the present invention further provides a transcatheter comprising a tubular middle layer, an outer layer located at the outer periphery of the middle layer, and an inner layer located at the inner periphery of the middle layer, wherein the tube wall of the middle layer has a penetrating part which communicates the inside and the outside of the middle layer in the radial direction of the middle layer, and the penetrating part has a connecting part for connecting the inner layer and the outer layer; the inner layer, the outer layer and the connecting part are integrally formed coatings.

As a further development of the invention, the coating comprises a plurality of segments of subcoat in the direction from the proximal end towards the distal end, the hardness of the subcoat near the proximal end being greater than the hardness of the subcoat near the distal end of the adjacent segments.

As a further improvement of the invention, the material at the juncture of the adjacent sub-coatings is a mixed material of the polymer materials corresponding to the two adjacent sub-coatings.

The beneficial effects of the invention are as follows: in the preparation method of the radial catheter, the middle layer is placed in the cavity of the coating die, gaps are formed on the outer periphery and the inner periphery of the middle layer, then a polymer solution is injected into the gaps, and after the polymer solution is solidified, an integrated coating can be formed on the inner periphery, the outer periphery and the penetrating part of the middle layer, so that the radial catheter is formed; on the one hand, no assembly gap exists between the inner layer and the middle layer, the wall thickness of the radial catheter can be reduced on the basis of maintaining the interventional performance of the radial catheter, and the problem of loose adhesion between the high polymer solution and the middle layer is avoided; on the other hand, the outer surface of the formed radial catheter is smoother, and all the penetrating parts can be filled with the liquid polymer solution, so that a connecting part for connecting the inner layer and the outer layer is formed in each penetrating part, and the stability of the radial catheter is improved.

Drawings

FIG. 1 is a flow chart of a method of preparing a transcatheter catheter of the present invention;

FIG. 2 is a simplified schematic diagram of a coating die in accordance with one embodiment of the present invention;

FIG. 3 is a schematic view of the molding assembly of FIG. 2;

FIG. 4 is a cross-sectional view of the molding assembly of FIG. 3 (with the intermediate layer positioned within the mold cavity);

fig. 5 is a schematic view of another angle of the molding assembly of fig. 3.

Detailed Description

The present invention will be described in detail with reference to the embodiments shown in the drawings, and reference is made to fig. 1 to 5, which are preferred embodiments of the present invention. It should be understood that these embodiments are not intended to limit the present invention, and that functional, method, or structural equivalents and alternatives falling within the scope of the present invention may be modified by any person skilled in the art to include such embodiments.

The words expressing position and direction described in the invention are all characterized in that the words are relative to an instrument operator, one end close to the instrument operator is a near end, and the other end far away from the instrument operator is a far end; the axial direction in the present invention refers to the longitudinal direction of the member. Furthermore, the terms first, second, etc. in the present invention are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying a number of technical features being indicated.

Referring to fig. 1 to 5, the present invention provides a method for preparing a transcatheter catheter and a coating mold 100, and the method for preparing a transcatheter catheter is performed by the coating mold 100 to prepare a transcatheter catheter.

The preparation method of the radial catheter comprises the following steps:

providing a tubular middle layer 10, wherein the pipe wall of the middle layer 10 is provided with a penetrating part which is communicated with the inside and the outside of the middle layer 10 along the radial direction of the middle layer 10;

placing the intermediate layer 10 in a cavity of a coating die 100 to form an outer layer cavity 23 positioned at the outer periphery of the intermediate layer 10 and an inner layer cavity 24 positioned at the inner periphery of the intermediate layer 10, wherein the penetrating part is communicated with the outer layer cavity 23 and the inner layer cavity 24;

injecting a polymer solution into the cavity, curing after the injection is finished, forming an outer layer of the radial catheter by the polymer solution cured in the outer layer cavity 23, forming an inner layer of the radial catheter by the polymer solution cured in the inner layer cavity 24, and forming a connecting part for connecting the outer layer and the inner layer by the polymer solution cured in the penetrating part;

and (5) demolding.

In the present invention, by placing the intermediate layer 10 in the cavity of the coating die 100, gaps are formed at both the outer periphery and the inner periphery of the intermediate layer 10, that is, the outer layer cavity 23 located at the outer periphery of the intermediate layer 10 and the inner layer cavity 24 located at the inner periphery of the intermediate layer 10, and then injecting a polymer solution into the gaps, an integrated coating layer is formed at the inner periphery, the outer periphery and the through-penetration of the intermediate layer 10 after the polymer solution is cured, wherein the coating layer located at the inner periphery of the intermediate layer 10 forms the inner layer of the radial catheter, the coating layer located at the outer periphery of the intermediate layer 10 forms the outer layer of the radial catheter, and the coating layer located in the through-penetration forms a connecting portion connecting the inner layer and the outer layer. On the one hand, no assembly gap exists between the inner layer and the middle layer 10, the wall thickness of the transcatheter can be reduced on the basis of maintaining the interventional performance of the transcatheter, and the problem of loose adhesion between the polymer solution and the middle layer 10 does not exist; on the other hand, the outer surface of the formed radial catheter is smoother, and all the penetrating parts can be filled with the liquid polymer solution, so that a connecting part for connecting the inner layer and the outer layer is formed in each penetrating part, and the stability of the radial catheter is improved.

In an embodiment, the tubular middle layer 10 is a hypotube, the penetrating portion is a cutting pattern penetrating through the wall of the hypotube, and parameters such as specific patterns/cutting density of the cutting pattern may be set according to requirements, which will not be described herein. Of course, the tubular middle layer 10 is not limited to this, and may be a braided tube, a spring tube, or any combination of a hypotube, a braided tube, and a spring tube in other embodiments.

Referring to fig. 2, the coating die 100 includes a hot melting assembly 1 for hot melting a polymer material into a polymer solution, a forming assembly 2, a conveying assembly 3 for conveying the polymer solution in the hot melting assembly 1 into the forming assembly 2, and a control unit for controlling the operation of the coating die 100. And the hot melting assembly 1 and the conveying assembly 3 are both in communication connection with the control unit.

Specifically, the hot melting assembly 1 includes a hot melting box 11 for placing a polymer material, and a hot melting heating member for hot melting the polymer material into a polymer solution, and the hot melting heating member is in communication connection with the control unit. After the polymer material is put into the hot-melting box 11, and the hot-melting heating element is started to heat the temperature in the hot-melting box 11 to the melting point of the polymer material, the polymer material in the hot-melting box 11 is hot-melted into a polymer solution.

As shown in fig. 3 to 5, the molding assembly 2 includes a housing 21 having a mounting cavity for placing a tubular member to be coated, and a mandrel 22 for being disposed in the mounting cavity to form a cavity with a cavity wall of the mounting cavity, the mandrel 22 being for being inserted into the member to be coated.

In the following, the coating die 100 according to the present invention will be described in detail by taking the radial catheter of the present invention as an example of the coating die 100, and the article to be coated is the tubular middle layer 10. Of course, the coating die 100 is not limited thereto, and may be applied to the coating of other tubular members to be coated.

Specifically, the housing 21 has an opening communicating with the installation cavity, and a door 211 for opening and closing the opening. Through which access to the mandrel 22, placement of the intermediate layer 10, removal of the formed radial catheter, etc. can be achieved. After the door 211 closes the opening, a closed installation cavity is formed.

The installation cavity and the mandrel 22 are cylindrical, and the axial extension directions of the installation cavity and the mandrel 22 are consistent with the extension direction of the intermediate layer 10. After the intermediate layer 10 is sleeved on the mandrel 22, that is, the mandrel 22 is inserted into the intermediate layer 10, and then the mandrel 22 sleeved with the intermediate layer 10 is placed at a preset position in the installation cavity from the opening and the door body 211 is closed, an outer layer cavity 23 is formed between the outer peripheral surface of the intermediate layer 10 and the cavity wall of the installation cavity, an inner layer cavity 24 is formed between the inner peripheral surface of the intermediate layer 10 and the mandrel 22, that is, an outer layer cavity 23 located at the outer periphery of the intermediate layer 10 and an inner layer cavity 24 located at the inner periphery of the intermediate layer 10 are formed.

It is known that the spindle 22 is removably attached within the mounting cavity.

Further, the mounting cavity and the axial direction of the mandrel 22 extend in the up-down direction, the corresponding intermediate layer 10 located in the mounting cavity also extends in the up-down direction, and the formed cavity also extends in the up-down direction. Specifically, after the mandrel 22 sleeved with the middle layer 10 is placed in the mounting cavity, the lower end of the mandrel 22 is in limiting connection with the cavity bottom wall of the mounting cavity, the upper end of the mandrel 22 is in limiting connection with the cavity top wall of the mounting cavity, and the lower end of the middle layer 10 is supported on the cavity bottom wall of the mounting cavity, so that preset gaps can be kept between the mandrel 22 and the middle layer 10 and between the middle layer 10 and the cavity wall of the mounting cavity, and the subsequent injection of polymer solution is facilitated to form an outer layer on the periphery of the middle layer 10 and an inner layer on the inner periphery of the middle layer 10.

Further, the conveying assembly 3 comprises a conveying pipeline 31 for communicating the hot melting box 11 and the cavity, and a conveying pump arranged on the conveying pipeline 31 for conveying the polymer solution, and the conveying pump is in communication connection with the control unit. The high polymer material in the hot melting box 11 is melted into high polymer solution, and after the mandrel 22 sleeved with the middle layer 10 is placed at a preset position in the installation cavity and the door body 211 is closed, the high polymer solution is conveyed forward by the conveying pump, so that the high polymer solution is conveyed from the hot melting box 11 into the cavity.

In one embodiment, the mounting cavity includes a cavity peripheral wall extending upwardly from a periphery of the cavity bottom wall. The shell 21 is provided with a feed inlet 25 communicated with the mounting cavity in a penetrating manner at a position corresponding to the peripheral wall of the cavity, and the conveying pipeline 31 is connected with the feed inlet 25. After the mandrel 22, which is sleeved with the intermediate layer 10, is placed at a preset position in the installation cavity from the opening and the door body 211 is closed, the conveying pipeline 31 is communicated with the outer layer cavity 23. The polymer solution fed into the outer cavity 23 flows into the inner cavity 24 through the penetration portion of the intermediate layer 10, so that the outer cavity 23, the penetration portion, and the inner cavity 24 are filled with the polymer solution.

Correspondingly, the step of injecting the polymer solution into the cavity and then curing is specifically as follows: the polymer solution is injected into the outer cavity 23, and the polymer solution in the outer cavity 23 flows into the inner cavity 24 through the penetration portion.

Further, the housing 21 is provided with a plurality of feed inlets 25 in a penetrating manner, the feed inlets 25 are arranged in pairs, and the feed inlets 25 in a pair are arranged in a radial direction of the mounting cavity in an opposite manner. When the polymer solution is injected into the cavity, the polymer solution synchronously enters the outer layer cavity 23 through the pair of feed inlets 25, so that the displacement of the middle layer 10 can be further avoided, and the stability of the coating die 100 is improved; meanwhile, the material injection efficiency can be improved, and the production efficiency of the radial catheter can be improved.

Specifically, one of the conveying assemblies 3 corresponds to one or more pairs of the feed inlets 25.

Further, the molding assembly 2 further includes a heating assembly 26 for heating the cavity, and the heating assembly 26 is communicatively connected to the control unit. Before the polymer solution is injected into the cavity, the heating assembly 26 is started to heat the cavity, so that the temperature in the cavity is raised to a first preset temperature, and the temperature can be kept at the first preset temperature until the injection is finished, wherein the first preset temperature is not lower than the melting point of the polymer material forming the polymer solution to be injected. Therefore, the polymer solution injected into the cavity can be kept in a liquid state until the injection is completed, and the polymer solution is facilitated to fill the outer cavity 23, the penetration portion, and the inner cavity 24.

Specifically, the first preset temperature is 15-25 ℃ higher than the melting point of the polymer material forming the polymer solution.

In one embodiment, the heating element 26 is a heating wire buried in the housing 21 and disposed around the mounting cavity. Can evenly heat the cavity. Of course, this is not a limitation.

Correspondingly, before the polymer solution is injected into the cavity, the preparation method of the radial catheter further comprises the following steps:

The heating assembly 26 is started to heat the temperature in the cavity of the material to be injected to a first preset temperature which is not lower than the melting point of the polymer material forming the polymer solution to be injected, and the temperature is kept at the end of the material injection.

Specifically, the first preset temperature is 15-25 ℃ higher than the melting point of the polymer material forming the polymer solution.

Further, the step of curing after the injection in the radial catheter preparation method is specifically as follows: the heating assembly 26 is turned off so that the polymer solution injected into the cavity cures to form the coating on the intermediate layer 10.

Further, the molding assembly 2 further includes a water circulation system (not shown) for cooling the cavity, and the water circulation system is in communication connection with the control unit. After the material injection is finished, the temperature of the cavity is reduced through the water circulation system, so that the cooling rate of the cavity is increased, the solidification speed of the polymer solution is increased, and the preparation efficiency of the radial catheter is improved.

Specifically, the water circulation system includes a pipe buried in the housing 21 and disposed around the installation cavity, and a water supply assembly for supplying water to the pipe. The pipeline and the heating wire are arranged at intervals.

Correspondingly, the step of curing after the injection in the radial catheter preparation method is specifically as follows: and turning off the heating component 26, and starting a water circulation system for cooling the cavity after the material feeding is finished until the temperature in the cavity is reduced to a second preset temperature, wherein the second preset temperature is lower than the melting point of the high polymer material forming the high polymer solution. So that the polymer solution injected into the cavity is cured to form the coating layer on the intermediate layer 10.

Specifically, the second preset temperature is 45-55 ℃ lower than the melting point of the polymer material forming the polymer solution.

Further, the transfer pump is a forward and reverse transfer pump, that is, the transfer pump can forward transfer the polymer solution, so that the polymer solution flows into the cavity through the transfer pipe 31, and the transfer pump can reverse transfer the polymer solution, so that the polymer solution flows back into the hot melting tank 11 through the transfer pipe 31 in a direction away from the cavity.

Correspondingly, in the radial catheter preparation method, after the material injection is finished and before solidification, the radial catheter preparation method further comprises the following steps: the polymer solution in the transfer duct 31 for transferring the polymer solution is transferred in a direction away from the cavity to empty the transfer duct 31. Specifically, the transfer pump is driven to reversely transfer the polymer solution to empty the polymer solution in the transfer pipe 31. Thereby, the polymer solution in the conveying pipeline 31 is prevented from solidifying and blocking the conveying pipeline 31 in the subsequent cooling and solidifying process.

Further, the molding assembly 2 also includes an ultrasonic generator 27 that acts on the mold cavity. The ultrasonic generator 27 is started while the polymer solution is injected into the cavity, so that the polymer solution can flow through each corresponding penetrating part, and the stability of the finally formed adding guide pipe is improved; at the same time, the bubbles in the polymer solution can be removed.

Specifically, the ultrasonic generator 27 is disposed on the housing 21 and is close to the corresponding mounting cavity, so as to improve the vibration effect of the ultrasonic generator 27 on the polymer solution in the cavity.

Correspondingly, in the method for preparing the catheter through the radius, the ultrasonic generator 27 acting on the cavity is started at the same time as the polymer solution is injected into the cavity.

Further, the cavity comprises a plurality of sections of sub cavities which are arranged along the up-down direction and are mutually communicated, and each sub cavity comprises an outer layer sub cavity and an inner layer sub cavity which correspond to the sub cavity. The hot melting assemblies 1 are in one-to-one correspondence with the sub-type cavities, and a plurality of the hot melting assemblies 1 are arranged at intervals along the up-down direction. Different types of polymer solutions can be injected into different type cavities according to requirements, so that the performance requirements of the radial catheter which is required to be prepared can be met, for example, the requirements that the hardness is gradually reduced and the radial catheter is gradually softened from the proximal end to the distal end can be met.

It is known that the types of polymer solutions in the outer layer sub-cavity, the inner layer sub-cavity, and the penetrating portions communicating the outer layer sub-cavity and the inner layer sub-cavity, which correspond to the respective sub-cavities, are identical.

Further, in the embodiment where the cavity includes a plurality of sub-cavities arranged in the up-down direction and communicated with each other, the heating elements 26 are in one-to-one correspondence with the sub-cavities, and the water circulation system is in one-to-one correspondence with the sub-cavities. Therefore, only the temperature of the sub-cavity to be injected needs to be heated and kept, and the temperature is prevented from affecting the cured polymer solution in the other sections of sub-cavities; meanwhile, the temperature of the sub-type cavity which is needed to solidify the polymer solution just after the material injection is finished is also reduced, and the temperature reduction effect is improved.

In the embodiment that the cavity comprises a plurality of sections of sub-cavities which are arranged along the up-down direction and are mutually communicated, the method for preparing the radial conduit comprises the steps of injecting a polymer solution into the cavity, and curing after the injection is finished: and injecting and curing the polymer solution of the corresponding type into the sub-cavity positioned at the lower side of the two adjacent sections of sub-cavities, and then injecting and curing the polymer solution of the corresponding type into the sub-cavity positioned at the upper side. I.e. from the bottom to the top of the mould cavity, the coating in each section of sub-mould cavity is formed in turn. Can avoid mixing different kinds of polymer solutions in the cavity and influence the overall performance of the radial catheter finally prepared.

Further, "after injecting and curing a polymer solution of a corresponding kind into a sub-cavity located at a lower side of two adjacent sub-cavities," the method comprises the following steps:

injecting the polymer solution of the corresponding type into the sub-cavity positioned at the lower side until the distance from the liquid level of the polymer solution to the top end of the sub-cavity is 2 mm-3 mm, continuously injecting the polymer solution of the corresponding type into the sub-cavity positioned at the lower side, simultaneously injecting the polymer solution corresponding to the sub-cavity positioned at the upper side into the sub-cavity to form a mixed solution, and ending the injection when the liquid level of the mixed solution exceeds the bottom end of the sub-cavity positioned at the upper side by 2 mm-3 mm, thereby solidifying the polymer solution;

and after the injected polymer solution is solidified, injecting the polymer solution of the corresponding type into the sub-cavity positioned on the upper side, and solidifying.

That is, a mixing section formed by mixing two polymer materials is formed at the junction of the two polymer materials, so that the hardness mutation brought by the junction of the two polymer materials can be reduced, the hardness mutation of the prepared radial catheter at the junction of the two polymer materials is smaller, and the pushing effect of the radial catheter is improved.

Specifically, before the corresponding polymer solution is injected into the corresponding sub-cavity, the heating assembly 26 corresponding to the sub-cavity to be injected is started to raise the temperature of the sub-cavity to be injected to a first preset temperature and keep the temperature until the injection is finished.

It is known that the first preset temperature is 15 to 25 ℃ higher than the melting point of the polymer material forming the polymer solution corresponding to the sub-type cavity.

Meanwhile, the end of the injection refers to the time when the liquid level of the mixed liquid exceeds the bottom end of the sub-cavity positioned at the upper side by 2 mm-3 mm.

Specifically, after the injection of the sub-cavity at the lower side is completed, the heating assembly 26 corresponding to the sub-cavity at the lower side is turned off, and at the same time, a water circulation system corresponding to the sub-cavity at the lower side after the injection is completed is started to cool the sub-cavity at the lower side, so that the temperature in the sub-cavity at the end of the injection is reduced to a second preset temperature, and the polymer solution in the sub-cavity at the lower side and the mixed solution at the junction of the sub-cavities at the upper side and the lower side are solidified.

It is known that the second preset temperature is 45-55 ℃ lower than the melting point of the polymer material forming the polymer solution corresponding to the sub-type cavity.

Further, after the heating element 26 corresponding to the lower-side sub-chamber is turned off, and before the water circulation system corresponding to the lower-side sub-chamber at the end of the injection is started, the method for preparing the transcatheter further comprises: and starting the conveying pumps in the conveying assemblies 3 corresponding to the two adjacent sub-cavities, so that the conveying pumps reversely convey the corresponding polymer assemblies, and the polymer solutions in the conveying pipelines 31 in the two conveying assemblies 3 are sucked back into the corresponding hot melting boxes 11, thereby avoiding the blockage of the conveying pipelines 31 caused by subsequent cooling.

Further, the polymer material forming the polymer solution includes silicone oil. The polymer material has certain lubricity, so that a coating formed by solidifying the polymer solution can replace an inner layer in the existing radial catheter and meet the performance requirement of the inner layer in the radial catheter.

Further, as shown in fig. 2, the coating die 100 includes a plurality of molding assemblies 2 arranged at intervals around the circumference of the hot-melt assembly 1, and a conveying assembly 3 respectively communicating the hot-melt assembly 1 with the plurality of molding assemblies 2. Therefore, a plurality of radial catheters can be formed at the same time, and the preparation efficiency of the radial catheters is improved.

It is known that, when the coating die 100 includes a plurality of molding assemblies 2 arranged at intervals around the circumference of the hot-melt assembly 1, and each cavity of the molding assemblies 2 has a plurality of sub-cavities, the plurality of molding assemblies 2 are arranged at intervals in the up-down direction, and the plurality of molding assemblies 2 are arranged at intervals around the circumference of each of the hot-melt assemblies 1.

In the following, taking the case 21 having one installation cavity and each cavity having three sub-cavities as an example, a specific description will be given of a method for preparing a radial pipe by using the coating die 100 according to the present invention, wherein from the bottom to the top of the cavity, the three sub-cavities are respectively a lower sub-cavity, a neutron cavity, and an upper sub-cavity, and the hot melting assemblies respectively corresponding to the lower sub-cavity, the neutron cavity, and the upper sub-cavity are: a lower hot melt assembly, a hot melt assembly, and an upper hot melt assembly; the conveying components respectively corresponding to the lower sub-cavity, the neutron cavity and the upper sub-cavity are as follows: a lower conveying assembly, a middle conveying assembly and an upper conveying assembly; the heating components respectively corresponding to the lower sub-cavity, the neutron cavity and the upper sub-cavity are as follows: a lower heating assembly, a middle heating assembly, and an upper heating assembly; the water circulation systems respectively corresponding to the lower sub-cavity, the neutron cavity and the upper sub-cavity are as follows: a lower water circulation system, a middle water circulation system and an upper water circulation system; the polymer solutions (polymer materials) corresponding to the lower sub-cavity, the neutron cavity and the upper sub-cavity are respectively: TPU, PEBAX and nylon, wherein the melting point of the nylon is 190 ℃, the melting point of the PEBAX is 160 ℃, and the melting point of the TPU is 120 ℃. The materials of the inner layer and the outer layer of the radial catheter which are finally formed are nylon, PEBAX and TPU in sequence from the proximal end to the distal end, so that the requirement of conveying performance that the hardness of the radial catheter is gradually reduced from the proximal end to the distal end is met. Of course, it is understood that the invention is not limited thereto.

The preparation method of the radial catheter specifically comprises the following steps:

taking out the core shaft 22, sleeving the intermediate layer 10 on the core shaft 22, then installing the core shaft 22 sleeved with the intermediate layer 10 at a preset position in the installation cavity, and closing the door body 211;

respectively placing TPU, PEBAX and nylon into a hot melting box of a lower hot melting assembly, a hot melting assembly and an upper hot melting assembly, starting a hot melting heating piece in each hot melting assembly to hot melt each polymer material into a polymer solution, wherein silicone oil is added into the polymer solution;

starting a lower heating assembly to heat the lower sub-cavity to 140 ℃, and preserving heat to keep the temperature in the lower sub-cavity at 140 ℃;

starting a conveying pump of the lower conveying assembly to positively convey the TPU solution into the lower sub-cavity, and simultaneously starting the conveying pump of the middle conveying assembly to positively convey the PEBAX solution until the liquid level of the mixed solution of the TPU solution and the PEBAX solution exceeds the bottom end of the sub-cavity by 2-3 mm when the distance between the liquid level of the TPU solution and the top end of the lower sub-cavity is 2-3 mm, and controlling the conveying pumps of the lower conveying assembly and the middle conveying assembly to stop material injection;

starting a conveying pump in the lower conveying assembly and the middle conveying assembly to reversely convey the polymer solution so as to empty the corresponding polymer solution in the conveying pipelines in the lower conveying assembly and the middle conveying assembly;

Starting a lower water circulation system to cool the lower sub-cavity to the temperature in the lower sub-cavity to 70 ℃, and at the moment, solidifying the TPU solution in the lower sub-cavity and the mixed solution at the junction of the lower sub-cavity and the neutron cavity to form a lower-stage coating;

the heating component heats the neutron cavity to 180 ℃ in starting, and keeps the temperature in the neutron cavity at 180 ℃;

the conveying pump of the middle conveying assembly is started to positively convey the PEBAX solution into the neutron cavity, and when the distance between the liquid level of the PEBAX solution and the top end of the neutron cavity is 2 mm-3 mm, the conveying pump of the upper conveying assembly is started to positively convey the nylon solution until the liquid level of the mixed solution of the nylon solution and the PEBAX solution exceeds the bottom end of the upper sub cavity by 2 mm-3 mm, and the conveying assembly and the conveying pump in the upper conveying assembly are controlled to stop material injection;

the middle conveying assembly and the conveying pump in the upper conveying assembly are started to reversely convey the polymer solution so as to clear the corresponding polymer solution in the conveying pipelines in the middle conveying assembly and the upper conveying assembly;

starting a reclaimed water circulation system to cool a neutron cavity to a temperature in the neutron cavity to 110 ℃, and at the moment, solidifying a PEBAX solution in the neutron cavity and a mixed solution positioned at the junction of the neutron cavity and an upper type cavity to form a middle section coating;

Starting an upper heating assembly to heat the upper sub-cavity to 210 ℃, and preserving heat to keep the temperature in the upper sub-cavity at 210 ℃;

starting a conveying pump of the upper conveying assembly to positively convey the nylon solution into the upper sub-cavity, and controlling the conveying pump in the upper conveying assembly to stop material injection when the nylon solution fills the upper sub-cavity;

starting a conveying pump in the upper conveying assembly to reversely convey the polymer solution so as to empty the nylon solution in a conveying pipeline in the upper conveying assembly;

starting a water feeding circulation system to cool the upper sub-cavity to 140 ℃ when the temperature in the upper sub-cavity is reduced, and solidifying the nylon solution in the upper sub-cavity to form an upper section coating;

finally, after cooling to normal temperature, the door 211 is opened, the formed radial catheter is removed together with the mandrel 22, and then the core is pulled to obtain the radial catheter.

Further, the invention also provides a radial catheter prepared by the radial catheter preparation method; or a transcatheter manufactured using the coating die 100 described above. The method for preparing the radial catheter and the coating mold 100 are described above, and are not described herein.

The radial catheter comprises a tubular middle layer 10, an outer layer positioned on the periphery of the middle layer 10 and an inner layer positioned on the inner periphery of the middle layer 10, wherein the pipe wall of the middle layer 10 is provided with a penetrating part which is communicated with the inside and the outside of the middle layer 10 along the radial direction of the middle layer 10, and the penetrating part is internally provided with a connecting part for connecting the inner layer and the outer layer; the inner layer, the outer layer and the connecting part are integrally formed coatings. On the one hand, no assembly gap exists between the inner layer and the middle layer 10, the wall thickness of the transcatheter can be reduced on the basis of maintaining the interventional performance of the transcatheter, and the problem of loose adhesion between the high polymer coating and the middle layer 10 does not exist; on the other hand, the outer surface of the formed radial catheter is smoother, and the inner layer, the outer layer and the connecting part are integrally formed, so that the stability of the radial catheter can be improved.

In an embodiment, the tubular middle layer 10 is a hypotube, the penetrating portion is a cutting pattern penetrating through the wall of the hypotube, and parameters such as specific patterns/cutting density of the cutting pattern may be set according to requirements, which will not be described herein. Of course, the tubular middle layer 10 is not limited to this, and may be a braided tube, a spring tube, or any combination of a hypotube, a braided tube, and a spring tube in other embodiments.

Further, the coating comprises a plurality of sections of sub-coatings from the proximal end to the distal end, and the hardness of the sub-coating near the proximal end in two adjacent sections of sub-coatings is higher than that of the sub-coating near the distal end. In one embodiment, the coating comprises three sections of sub-coatings, wherein the high polymer materials of the three sections of sub-coatings are nylon, PEBAX and TPU respectively from the proximal end to the distal end.

Further, the material at the junction of the adjacent sub-coatings is a mixed material of the polymer materials corresponding to the two adjacent sub-coatings. The hardness mutation of the radial catheter at the junction of the adjacent sub-coatings is smaller, and the pushing effect of the radial catheter is improved.

In summary, in the method for preparing the radial catheter according to the present invention, the intermediate layer 10 is placed in the cavity of the coating mold 100, gaps are formed on the outer periphery and the inner periphery of the intermediate layer 10, then a polymer solution is injected into the gaps, and after the polymer solution is cured, an integral coating is formed on the inner periphery, the outer periphery and the penetrating portion of the intermediate layer 10, so as to form the radial catheter; on the one hand, no assembly gap exists between the inner layer and the middle layer 10, the wall thickness of the transcatheter can be reduced on the basis of maintaining the interventional performance of the transcatheter, and the problem of loose adhesion between the polymer solution and the middle layer 10 does not exist; on the other hand, the outer surface of the formed radial catheter is smoother, and all the penetrating parts can be filled with the liquid polymer solution, so that a connecting part for connecting the inner layer and the outer layer is formed in each penetrating part, and the stability of the radial catheter is improved.

It should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is for clarity only, and that the skilled artisan should recognize that the embodiments may be combined as appropriate to form other embodiments that will be understood by those skilled in the art.

The above list of detailed descriptions is only specific to practical embodiments of the present invention, and is not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the spirit of the present invention should be included in the scope of the present invention.

Claims (28)

1. A method for preparing a radial catheter, which is characterized in that: the method comprises the following steps:

providing a tubular middle layer, wherein the pipe wall of the middle layer is provided with a penetrating part which is communicated with the inside and the outside of the middle layer along the radial direction of the middle layer;

placing the middle layer in a cavity of a coating die to form an outer layer cavity positioned at the periphery of the middle layer and an inner layer cavity positioned at the inner periphery of the middle layer, wherein the penetrating part is communicated with the outer layer cavity and the inner layer cavity;

Injecting a polymer solution into the cavity, curing after the injection is finished, forming an outer layer of the radial catheter by the polymer solution cured in the outer layer cavity, forming an inner layer of the radial catheter by the polymer solution cured in the inner layer cavity, and forming a connecting part for connecting the outer layer and the inner layer by the polymer solution cured in the penetrating part;

and (5) demolding.

2. A method of preparing a transcatheter according to claim 1, wherein: the step of injecting the polymer solution into the cavity and then curing is specifically as follows: and injecting a polymer solution into the outer-layer cavity, wherein the polymer solution in the outer-layer cavity flows into the inner-layer cavity through the penetrating part.

3. A method of preparing a transcatheter according to claim 1, wherein: and (3) simultaneously injecting a polymer solution into the cavity, and starting an ultrasonic generator acting on the cavity.

4. A method of preparing a transcatheter according to claim 1, wherein: before the polymer solution is injected into the cavity, the preparation method of the radial catheter further comprises the following steps:

starting a heating assembly to heat the temperature in the cavity of the material to be injected to a first preset temperature and preserving heat until the material injection is finished, wherein the first preset temperature is not lower than the melting point of the polymer material forming the polymer solution to be injected.

5. A method of preparing a transradial catheter according to claim 4, wherein: the curing after the material injection is finished is as follows: and closing the heating assembly, and starting a water circulation system for cooling the cavity after feeding until the temperature in the cavity is reduced to a second preset temperature, wherein the second preset temperature is lower than the melting point of the high polymer material forming the high polymer solution.

6. A method of preparing a transcatheter according to claim 1, wherein: the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top, the sub-cavity comprises an outer sub-cavity and an inner sub-cavity which correspond to the sub-cavity, and the multi-section sub-cavity corresponds to a plurality of polymer solutions respectively; and injecting and curing the polymer solution of the corresponding type into the sub-cavity positioned at the lower side of the two adjacent sections of sub-cavities, and then injecting and curing the polymer solution of the corresponding type into the sub-cavity positioned at the upper side.

7. A method of preparing a transradial catheter according to claim 6, wherein: the method for injecting and curing the polymer solution of the corresponding type into the sub-cavity positioned at the lower side of the two adjacent sections of sub-cavities comprises the following steps:

Injecting the polymer solution of the corresponding type into the sub-cavity positioned at the lower side until the distance from the liquid level of the polymer solution to the top end of the sub-cavity is 2 mm-3 mm, continuously injecting the polymer solution of the corresponding type into the sub-cavity positioned at the lower side, simultaneously injecting the polymer solution corresponding to the sub-cavity positioned at the upper side into the sub-cavity to form a mixed solution, and ending the injection when the liquid level of the mixed solution exceeds the bottom end of the sub-cavity positioned at the upper side by 2 mm-3 mm, thereby solidifying the polymer solution;

after the polymer solution is solidified, the polymer solution of the corresponding type is injected into the sub-cavity positioned on the upper side and solidified.

8. A method of preparing a transcatheter according to claim 1, wherein: after the injection is finished and before the solidification, the preparation method of the radial catheter further comprises the following steps: and conveying the polymer solution in the conveying pipeline for conveying the polymer solution to the direction away from the cavity so as to empty the conveying pipeline.

9. A method of preparing a transradial catheter according to claim 4, wherein: the mould cavity comprises a plurality of sections of sub-mould cavities which are communicated with each other from bottom to top, the sub-mould cavity comprises an outer sub-mould cavity and an inner sub-mould cavity which correspond to the sub-mould cavity, the plurality of sections of sub-mould cavities respectively correspond to a plurality of polymer solutions, and after the polymer solutions of corresponding types are injected into the sub-mould cavities positioned at the lower side in two adjacent sections of sub-mould cavities and solidified, the polymer solutions of corresponding types are injected into the sub-mould cavities positioned at the upper side and solidified; the step of starting the heating assembly to heat the temperature in the cavity to a first preset temperature and preserving heat until the material injection is finished is specifically as follows: and starting a heating assembly corresponding to the sub cavity to be injected so as to heat the temperature of the sub cavity to be injected to a first preset temperature and preserving heat until the injection is finished.

10. A method of preparing a transradial catheter according to claim 4, wherein: the mould cavity comprises a plurality of sections of sub-mould cavities which are communicated with each other from bottom to top, the sub-mould cavity comprises an outer sub-mould cavity and an inner sub-mould cavity which correspond to the sub-mould cavity, the plurality of sections of sub-mould cavities respectively correspond to a plurality of polymer solutions, and after the polymer solutions of corresponding types are injected into the sub-mould cavities positioned at the lower side in two adjacent sections of sub-mould cavities and solidified, the polymer solutions of corresponding types are injected into the sub-mould cavities positioned at the upper side and solidified; the step of starting the water circulation system for cooling the cavity until the temperature in the cavity is reduced to a second preset temperature is specifically as follows: and starting a water circulation system corresponding to the material-injected sub-cavity to reduce the temperature in the material-injected sub-cavity to a second preset temperature.

11. A method of preparing a transradial catheter according to claim 4, wherein: the first preset temperature is 15-25 ℃ higher than the melting point of the polymer material forming the polymer solution.

12. A method of preparing a transradial catheter according to claim 5, wherein: the second preset temperature is 45-55 ℃ lower than the melting point of the polymer material forming the polymer solution.

13. A method of preparing a transcatheter according to claim 1, wherein: the polymer material forming the polymer solution comprises silicone oil.

14. A method of preparing a transcatheter according to claim 1, wherein: the middle layer is a hypotube.

15. A coating die, characterized in that: comprising the following steps:

the hot melting assembly comprises a hot melting box for placing a high polymer material and a hot melting heating piece for hot melting the high polymer material into a high polymer solution;

the molding assembly comprises a shell with a mounting cavity for placing a tubular piece to be coated, and a mandrel arranged in the mounting cavity to form a cavity with the cavity wall of the mounting cavity, wherein the mandrel is used for being inserted into the piece to be coated;

the conveying assembly comprises a conveying pipeline communicated with the hot melting box and the cavity and a conveying pump arranged on the conveying pipeline for conveying the polymer solution.

16. The coating die of claim 15, wherein: the molding assembly also includes a heating assembly that heats the cavity.

17. The coating die of claim 16, wherein: the heating component is a heating wire buried in the shell and arranged around the mounting cavity.

18. The coating die of claim 16, wherein: the cavity extends along the up-down direction; the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top; the heating components are in one-to-one correspondence with the sub-type cavities.

19. The coating die of claim 15, wherein: the molding assembly further comprises a water circulation system for cooling the cavity.

20. The coating die of claim 19, wherein: the cavity extends along the up-down direction; the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top; the water circulation systems are in one-to-one correspondence with the sub-type cavities.

21. The coating die of claim 15, wherein: the cavity extends along the up-down direction; the cavity comprises a plurality of sections of sub-cavities which are communicated with each other from bottom to top; the hot melting assemblies are in one-to-one correspondence with the sub-type cavities.

22. The coating die of claim 15, wherein: the coating die comprises a plurality of forming assemblies and conveying assemblies, wherein the forming assemblies are circumferentially arranged around the hot melting assembly at intervals, and the conveying assemblies are respectively communicated with the hot melting assembly and the forming assemblies.

23. The coating die of claim 15, wherein: the molding assembly further includes an ultrasonic generator disposed on the housing and proximate to the mounting cavity.

24. The coating die of claim 15, wherein: the shell is penetrated and provided with a plurality of feeding holes communicated with the installation cavity, the feeding holes are arranged in pairs, and the feeding holes are oppositely arranged in the radial direction of the installation cavity.

25. A transcatheter catheter, characterized by: the transradial catheter is prepared by the method for preparing a transradial catheter according to any one of claims 1 to 14; or the radial catheter is prepared by using the coating die of any one of claims 15 to 24.

26. A transcatheter comprises a tubular middle layer, an outer layer positioned at the periphery of the middle layer and an inner layer positioned at the inner periphery of the middle layer, wherein the pipe wall of the middle layer is provided with a penetrating part which is communicated with the inside and the outside of the middle layer along the radial direction of the middle layer, and the penetrating part is internally provided with a connecting part for connecting the inner layer and the outer layer; the method is characterized in that: the inner layer, the outer layer and the connecting part are integrally formed coatings.

27. The transradial catheter of claim 26, wherein: the coating comprises a plurality of sections of sub-coatings from the proximal end to the distal end of the transcatheter catheter, and the hardness of the sub-coating near the proximal end of two adjacent sections of sub-coatings is higher than that of the sub-coating near the distal end.

28. The transradial catheter of claim 27, wherein: the material at the junction of the adjacent sub-coatings is the mixed material of the polymer materials corresponding to the two adjacent sub-coatings.