JP6796685B2 - How to manufacture a tubular body - Google Patents

Description

The present invention relates to a method for producing a tubular body.

Tubular bodies, especially medical tubular bodies, are generally medical devices for treating various diseases caused by the narrowing or obstruction of blood vessels or other in vivo lumens. In particular, a stent is a medical device that is placed in a lesion to expand the lesion such as a stenosis or occlusion site from the inside and maintain the inner diameter of the lumen.

The surface of a medical tubular body represented by a stent is required to be very smooth. If the surface is rough, it can cause inflammation by damaging or overstimulating the tissue during or after transplantation into the human body, so the surface is generally smoothed in the post-stent manufacturing process. It is processed to finish.

As a method for processing the surface of a medical tubular body, an electrolytic polishing method is preferably used.

For example, in Patent Document 1, a plurality of anodes are arranged at equal intervals so as to surround the outer periphery of the stent, the stent is rotated, a central cathode is arranged inside the stent, and further, curved outer side around the outer periphery of the stent. A method has been proposed in which the inner and outer surfaces of a stent are electrolyzed at the same time by using a cathode.

Further, Patent Document 2 proposes an electrolytic polishing method in which a stent rotates with the rotation of a roller and the electrical contact between the anode wire and the stent changes continuously.

Special Table 2003-522841 Special Table 2007-533845

The electrolytic polishing methods of Patent Document 1 and Patent Document 2 provide a method in which an operator can work safely because the operator does not touch the electrolytic solution or the electrode during the electrolytic polishing operation, but a complicated device is required for this purpose. There is a problem that it is difficult to obtain a uniform flow of the electrolytic solution. Furthermore, by rotating the stent, the electrical contact between the stent and the anode conductive member is moved, but the actual area of electrical contact between the stent and the anode conductive member is not large, so that the current density is not high. There is a problem that uniformity is likely to occur, and a portion having non-uniform polishing is generated on the electrolyzed surface.

In order to solve the above problems, it is an object of the present invention to provide a method for producing a tubular body, which can achieve uniform electrolytic polishing with less unevenness by using a simple method and an apparatus in electrolytic polishing of a tubular body. ..

The present inventor has completed the present invention as a result of diligent studies for solving the above problems. That is, the present invention provides the following methods for producing tubular bodies [1] to [8].
[1] A method for producing a tubular body, which comprises the following steps (a) and (b) at least once.
(A) A step of electrolyzing the outer surface of the tubular body by supporting the inner surface of the tubular body from the inside by an anode conductive member that makes electrical contact with the tubular body (b) Anode conductivity that makes electrical contact with the tubular body. A process in which the outer surface of the tubular body is supported from the outside by a sex member and the inner surface of the tubular body is electrolyzed.
[2] In the step (a), at least a part of the tubular body is in contact with the anode conductive member on the inner surface of the tubular body in a state where the diameter is expanded by 0.1 mm or more and 2.0 mm or less from the reference inner diameter. The method for producing a tubular body according to [1].
[3] In the step (b), at least a part of the tubular body is in contact with the anode conductive member on the outer surface of the tubular body in a state where the diameter is reduced by 0.1 mm or more and 2.0 mm or less from the reference outer diameter. The method for producing a tubular body according to [1].
[4] The method for producing a tubular body according to any one of [1] to [3], wherein the number of steps (b) is less than the number of steps (a).
[5] The method for producing a tubular body according to any one of [1] to [4], wherein the step (a) and the step (b) are sequentially performed once or more.
[6] The method for producing a tubular body according to [5], wherein one electrolytic polishing time in step (b) is shorter than one electrolytic polishing time in step (a).
[7] In the step (a), a voltage is supplied in a range of 10 seconds or more and 60 seconds or less for electrolytic polishing, and in the step (b), a voltage is supplied in a range of 3 seconds or more and 10 seconds or less for electrolytic polishing. The method for producing a tubular body according to [6], which comprises a step of:
[8] The method for producing a medical tubular body according to any one of [1] to [7], wherein the tubular body is a stent.

According to the present invention, electropolishing can be performed evenly and uniformly using a simple method and apparatus, so that a tubular body having excellent smoothness can be produced.

It is a schematic diagram which shows the conventional general electrolytic polishing method. It is a schematic diagram which shows the electrolytic polishing method which is one Embodiment of this invention. It is sectional drawing in the cut surface AA'in FIG. It is a schematic diagram which shows the electrolytic polishing method which is one Embodiment of this invention. It is sectional drawing in the cut surface BB'in FIG.

The method for producing a tubular body of the present invention includes a step of bringing the anode conductive member into contact with the inner surface of the tubular body to electropolish the outer surface while supporting the tubular body, and contacting the anode conductive member with the outer surface of the tubular body. It is a manufacturing method including one or more steps of electrolytically polishing the inner surface of the tubular body while supporting the tubular body.

By polishing the inner surface and the outer surface of the tubular body separately in this way, the polishing process can be performed under a uniform current density distribution, so that a tubular body having excellent smoothness can be manufactured.

In the present invention, the step of polishing the inner surface and the step of polishing the outer surface may be included at least once, and the inner surface may be polished first or the outer surface may be polished first. Further, either the outer surface or the inner surface may be continuously polished a plurality of times, and then the other surface may be polished.

Hereinafter, as a method for producing a tubular body according to the present invention, an embodiment using a stent as a tubular body as an example will be described in detail with reference to the drawings, but the present invention is not limited thereto.

<Tubular body>
For tubular bodies, especially medical tubular bodies, for example, (a) a coil-shaped type made of a single linear metal or polymer material, (b) a metal tube cut out by a laser or the like, ( C) There are types that are assembled by welding linear members with a laser or the like, and (d) types that are made by weaving multiple linear metals.
The medical tubular body (hereinafter, may be referred to as a tubular body) according to the present invention includes, for example, at least the outer surface of the tubular body from a first diameter which is a size inserted into the internal luminal structure. Examples include a tubular body that expands to a second diameter, part of which contacts the blood vessel wall. In particular, a stent can be preferably used as a medical tubular body used for plasty of an internal luminal structure such as a blood vessel, a ureter, and a bile duct.

The material used for the stent is not particularly limited as long as it can withstand deformation such as diameter expansion and diameter reduction and indwelling, but it is medical stainless steel such as 316L stainless steel, tantalum, and Co-Cr (cobalt chromium) alloy. A Ni—Ti (nickel titanium) alloy or the like can be preferably used.

As a method for producing a metal stent, a method in which a tubular material is cut out in a mesh shape by a laser and then electropolished can be preferably used.

Electropolishing involves laser machining of the strut part, which is the bent linear part of the stent, removal of the surface oxide film generated by heat treatment after laser machining, and rounding (round shape) of the sharp edges of the strut cross section. It is done for the purpose of. Electropolishing is preferably performed as a final finishing step for various purposes such as reducing metal elution, improving fatigue properties, and improving cleanliness.

<Anode conductive member>
The material of the anode conductive member 13 is not particularly limited as long as it has sufficient conductivity, and examples thereof include metals such as stainless steel, titanium, copper, aluminum, platinum, and gold, or alloys thereof. it can.

The shape of the anode conductive member 13 may be, for example, a plate shape, a core shape, a rod shape, or a wire shape as long as it can support the inner surface or the outer surface of the stent 14, and is shown in FIGS. 3 and 5. It may have a pipe-like structure. A pipe-shaped anode conductive member can be preferably used in that the area of the electrical contact 18 can be increased.

<Cathode>
The material of the cathode 16 is not particularly limited as long as it has sufficient conductivity, and examples thereof include metals such as stainless steel, titanium, copper, aluminum, platinum, and gold, or alloys thereof.

The shape of the cathode 16 is not particularly limited as long as the stent 14 can be electropolished, but examples thereof include a plate shape, a core shape, a rod shape, a wire shape, and the like, in order to increase the surface area of the cathode 16. Further, a mesh shape or a punching shape may be formed on the cathode 16 for the purpose of avoiding air bubbles, temperature changes and concentration gradients of ions in the liquid generated during electrolytic polishing.

<Electropolishing method>
FIG. 1 shows a conventional general electrolytic polishing method for a stent in which an electrode is brought into contact with the stent for electrolytic polishing.

In the electrolytic polishing, in the electrolytic solution 17 stored in the electrolytic solution tank 15, the anode conductive member 13 connected to the positive electrode of the power supply 11 by the conductive wire 12a is in contact with the stent 14 to be polished. Further, the cathode 16 connected to the negative electrode of the power supply 11 by the conductive wire 12b is installed so as to be separated from the stent 14. When a voltage is applied between the anode conductive member 13 and the cathode 16 in such an arrangement state, the metal element on the surface of the stent 14 acting as the anode dissolves in the electrolytic solution 17. As a result, the stent can be electropolished to make the surface smooth and glossy.

However, in the conventional general electropolishing method, the region of the electrical contact 18 between the stent 14 and the anode conductive member 13 is not polished, and the region around the electrical contact in the liquid tank is compared with other regions. Since the current density is greatly increased, the current density in the liquid tank becomes non-uniform, and as a result, polishing non-uniformity (polishing unevenness) tends to occur.

2 to 5 show a schematic view and a cross-sectional view of an embodiment of the present invention.
2 and 3 show a step of electrolytic polishing the outer surface of the stent 14 in a state where the anode conductive member 13 is in contact with the inner surface of the stent 14, which is the step (a) of the present invention.

On the other hand, FIGS. 4 and 5 show a step of electrolytically polishing the inner surface of the stent 14 in a state where the anode conductive member 13 is in contact with the outer surface of the stent 14, which is the step (b) of the present invention.
By performing electropolishing so as to include each of the steps (a) and (b) at least once, it is possible to perform electropolishing uniformly on both the outer and inner surfaces of the stent 14.

The step (a) may be performed first, or the step (b) may be performed first. Further, it is also possible to perform either the step (a) or the step (b) continuously a plurality of times and then perform the other step.

In the manufacturing method of the present invention, the total area of the electrical contact 18 in which the stent 14 and the anode conductive member 13 are in contact with each other is the total area of the stent 14 in that the surface smoothness is excellent and a stent having uniform dimensions can be easily obtained. It is preferable that they are in contact with each other at least 50% or more of the inner area or the outer area. By making the area of the electrical contact 18 sufficiently large, it is easy to obtain a uniform current density of the electrolytic solution around the stent 14.

In the step (a), the anode conductive member 13 and the stent 14 are brought into contact with each other from the viewpoint that the stent 14 can be easily fixed without causing plastic deformation or breakage during electrolytic polishing and local unevenness of the current density is unlikely to occur. At that time, it is preferable to bring at least a part of the stent 14 into contact with the diameter expanded from the reference inner diameter. Similarly, in the step (b), at least a part of the stent 14 is reduced from the reference outer diameter. It is preferable to make contact with.

In particular, in that it is easy to stably fix the stent and to obtain a smooth polished surface, it is preferable that the stent is in contact with the diameter expanded or reduced by 0.1 mm or more and 2.0 mm or less. It is particularly preferable to make contact in a state where the diameter is expanded or reduced by 1.0 mm or more.

By pressing the stent 14 with the anode conductive member 13, the contact becomes stronger and the current flows more easily, so that the current density in the region around the electrical contact 18 tends to become uniform, and the electrolytic solution around the stent 14 becomes uniform. Since it is easy to make the current density uniform, it is possible to obtain a polished surface having excellent smoothness with less uneven polishing and a stent having uniform dimensions with less unevenness.

General coronary artery and / or intravascular stents can be designed in the range of about 7 to about 200 mm in length and about 1 to about 12 mm in diameter, but the present invention even for stents 14 of sizes outside the above range. Is preferably brought into contact with the anode conductive member 13 so that the diameter is expanded or reduced.

The reference inner diameter or reference outer diameter in the present invention is the diameter of the inner surface of the tubular body (hereinafter, may be referred to as the inner diameter) before electrolytic polishing in the manufacture of the medical tubular body, or the outer surface of the tubular body. Indicates the diameter (hereinafter, may be referred to as the outer diameter).

During electropolishing, the cathode 16 is arranged on the opposite surface side of the surface in contact between the stent 14 and the anode conductive member 13 so as to be separated from the stent 14. For example, in step (a), the cathode 16 is arranged so as to surround the outer circumference of the stent 14 so as to be separated from the stent 14.

Further, the cathode 16 has a constant distance from the stent 14 (hereinafter, may be referred to as a distance between electrodes) on the outer peripheral surface of the stent 16 so that a constant electric field can be continuously applied to the stent 14. It is preferable to have a curved shape as well as the shape.

In the step (a), the distance between the electrodes of the stent 14 and the cathode 16 is not easily affected by bubbles generated during electrolytic polishing, temperature changes, concentration gradients of ions in the liquid, etc., and a smooth treated surface can be easily obtained. The lower limit is preferably 10 mm or more, more preferably 20 mm or more, particularly preferably 30 mm or more, and the upper limit is 100 mm or less from the viewpoint of preventing contact between each other or easily controlling the amount of polishing in electrolytic polishing per unit time. Is preferable, 90 mm or less is more preferable, and 80 mm or less is particularly preferable.
In the step (a), the number of cathodes 16 is not particularly limited, but one may be configured so as to cover the entire circumference of the stent 14, or the stent 14 may be configured by being divided.
In the step (a), the surface area of the cathode 16 is preferably at least twice as large as the surface area of the stent 14 from the viewpoint of electron transfer.

In the step (b), it is preferable that the cathode 16 is arranged in the vicinity of the center of the inner circumference of the stent 14 so as to be separated from the stent 14.
Further, the cathode 16 has a curved shape so that the distance between the electrodes with the stent 14 is constant, or a rod-shaped or pipe-shaped shape in that it is easy to continuously apply a constant electric field to the stent 14. It is preferable to have.

In step (b), it is preferable that the distance between the electrodes of the stent 14 and the cathode 16 is long so as not to cause contact between the electrodes.
In the step (b), the number of cathodes 16 is not particularly limited, but one may be configured so as to be surrounded by the inner surface of the stent 14, or the number of cathodes 16 may be divided and configured.

The liquid tank 15 stores the electrolytic solution 17. The electrolytic solution 17 is not particularly limited, and examples thereof include known alcohol-based or sulfuric acid-based aqueous solutions in the case of Ni—Ti (nickel titanium) alloys. The liquid tank 15 is preferably made of a material that is not corroded by the electrolytic solution 17. Further, during electrolytic polishing, it is preferable to stir the electrolytic solution 17 with a magnetic stirrer, a circulation pump, or the like because it is possible to suppress the dispersion of bubbles generated during electrolytic polishing, the temperature change, and the concentration gradient of ions in the liquid. Alternatively, the electrolytic solution 17 may be agitated by causing the anode conductive member 13 itself to perform operations such as rotation and rocking separately or in cooperation with the anode conductive member 13.

A voltage is applied to the anode conductive member 13, the stent 14 and the cathode 16 that make up the anode, allowing the stent 14 to be electropolished to the desired smoothness.
The electrolytic polishing time in the present invention is the time during which the anode conductive member 13 is brought into contact with the stent 14 and a voltage is applied.

The preferable voltage value for electrolytic polishing is not particularly limited as long as a smooth surface can be obtained, but a voltage value suitable for the metal material to be used and the electrolytic solution may be selected. For example, Ni—Ti (nickel titanium) alloy In the case, the range of 10 to 30 V is preferable.

The number of times of electrolytic polishing is not particularly limited as long as a smooth surface can be obtained, but it is preferable to repeat the steps (a) and (b) a total of 2 to 30 times.

Since a general coronary artery and / or an intravascular stent can be designed in the range of about 1 to about 12 mm in diameter, the distance between the electrodes of the cathode 16 and the stent 14 is set in the step (b) rather than the step (a). The number of times of electropolishing is the step (a) because it is often substantially smaller due to the limitation, it is easy to diffuse the bubbles generated during electropolishing, and it is easy to suppress the temperature change and the concentration gradient of ions in the liquid. It is preferable that the number of steps (b) is less than that of step (b).

Further, in order to maintain the surface properties and the dimensional shape of the outer and inner surfaces of the stent 14, it is preferable to repeat the steps (a) and (b) sequentially one or more times.

When the steps (a) and (b) are sequentially repeated one or more times, the distance between the electrodes of the cathode 16 and the stent 14 is more limited in the step (b) than in the step (a), as described above. Therefore, since it is often substantially smaller, it is easy to diffuse bubbles generated during electrolytic polishing, and it is easy to suppress temperature changes and concentration gradients of ions in the liquid. Therefore, one-time electrolytic polishing in step (a) It is preferable that the time for one electrolytic polishing in step (b) is shorter than the time.

As for the time for applying the voltage, that is, the electrolytic polishing time, in the step (a), the lower limit of one electrolytic polishing time is preferably 10 seconds or more, and particularly preferably 20 seconds or more. The upper limit is preferably 60 seconds or less, and particularly preferably 40 seconds or less.

The lower limit of the electrolytic polishing time for one step (b) is preferably 3 seconds or more, and particularly preferably 5 seconds or more. The upper limit is preferably 10 seconds or less, and particularly preferably 8 seconds or less.

It is also possible to remove the stent 14 from the electrolytic solution 17 in each of the steps (a) or (b) and wash the stent 14 with alcohol, water, nitric acid, or a solution in which they are combined.
It is preferable to repeat electropolishing several times and finally to wash by immersing in an ultrasonic bath at room temperature for 1 to 30 minutes.

The method for producing a tubular body of the present invention can be preferably used for a medical tubular body because a smooth surface can be easily obtained.

As described above, the method for manufacturing a stent according to the embodiment of the present invention has been described using a specific example, but the present invention is not limited by the above-described embodiment and conforms to the gist of the above and the following. It is also possible to make changes to the extent that it is possible, and all of them are included in the technical scope of the present invention.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples.
(Example 1)
A nickel titanium alloy stent 14 having an outer diameter of 8.0 mm and an inner diameter of 7.6 mm was prepared.
(A) Step The stent 14 is inserted through a pipe-shaped SUS304 anode conductive member 13 having an outer diameter of 8.0 mm so that the stent 14 has an enlarged diameter (+0.4 mm), and the anode is conductive. The outer surface of the sex member 13 was fixed in contact with the entire inner surface of the stent 14 (100% of the inner area of the stent).

An electrolytic solution 17, which is a commercially available electrolytic polishing solution for Ti alloys, is stored in the electrolytic solution tank 15, and has a curved shape so that the distance between the electrodes of the stent 14 is equidistant (45 mm to 55 mm). A cathode 16 made of SUS304 was installed. (The recommended voltage of the electrolytic solution 17 is 20 V.)
Electric power was supplied to the electrolytic solution 17 at a voltage of 20 V for 30 seconds, and the stent 14 was immersed in the electrolytic solution 17 to perform electrolytic polishing of the outer surface of the stent 14. After the power supply is completed, the stent 14 is washed with water and dried to change the electrical contact 18 between the stent 14 and the anode conductive member.

(B) Step The stent 14 is inserted through a pipe-shaped SUS304 anode conductive member 13 having an inner diameter of 7.6 mm so that the stent 14 has a reduced diameter (-0.4 mm diameter), and the anode is conductive. The inner surface of the sex member 13 was fixed in contact with the entire outer surface of the stent 14 (100% of the outer area of the stent).

In the electrolytic solution tank 15, an electrolytic solution 17, which is a commercially available electrolytic polishing solution for Ti alloys, is stored, and a rod-shaped SUS304 is provided so that the distance between the electrodes with the stent 14 is equidistant (3 mm to 4 mm). A cathode 16 made of titanium was installed. (The recommended voltage of the electrolytic solution 17 is 20 V.)
Electric power was supplied to the electrolytic solution 17 at a voltage of 20 V for 5 seconds, and the stent 14 was immersed in the electrolytic solution 17 to perform electrolytic polishing of the inner surface of the stent 14. After the power supply is completed, the stent 14 is washed with water and dried to change the electrical contact 18 between the stent 14 and the anode conductive member.

After that, the step (a) was carried out three times in succession, and then the steps (b) and (a) were alternately carried out three times each.

(Comparative Example 1)
A nickel titanium alloy stent 14 having an outer diameter of 8.0 mm and an inner diameter of 7.6 mm was prepared.
(A) Step The same method as in step (a) of Example 1 except that the stent 14 was fixed with a clip-shaped SUS304 anode conductive member 13 (contact with 5% of the total area of the inner surface of the stent). , 8 times in a row.

(Comparative Example 2)
A nickel titanium alloy stent 14 having an outer diameter of 8.0 mm and an inner diameter of 7.6 mm was prepared.
Only the step (a) of Example 1 was repeated eight times in succession.

(Comparative Example 3)
A nickel titanium alloy stent 14 having an outer diameter of 8.0 mm and an inner diameter of 7.6 mm was prepared.
Only the step (b) of Example 1 was repeated eight times in succession.

(result)
As a result of the electrolytic polishing methods of Example 1 and Comparative Examples 1 to 3, electrolytic polishing was possible in all of the examples. In particular, in Example 1, both the outer surface and the inner surface could be polished until the surface of the stent 14 was uniformly glossy.

On the other hand, in Comparative Example 1, although the outer and inner surfaces of the stent 14 were electropolished, burrs remained on the polished surface of the inner surface as compared with the outer surface, and uneven polishing was observed on the outer and inner surfaces of the stent 14. Was done.

In Comparative Example 2, although the outer surface of the stent 14 was electropolished, burrs remained on the polished surface of the inner surface as compared with the outer surface, and uneven polishing was observed on the outer and inner surfaces of the stent 14.

In Comparative Example 3, although the inner surface of the stent 14 was electropolished, burrs remained on the polished surface of the outer surface as compared with the inner surface, and uneven polishing was observed on the outer and inner surfaces of the stent 14.

From this, it can be seen that the electrolytic polishing method of the present invention can achieve uniform electrolytic polishing evenly by a simple method.

11 Power supply 12a, 12b Conductive wire 13 Anode conductive member 14 Stent 15 Electrolyte tank 16 Cathode 17 Electrolyte 18 Electrical contact

Claims (17)

A method for producing a tubular body, which comprises the following steps (a) and (b) at least once.
(A) A step of electrolytically polishing the outer surface of the tubular body by supporting the entire inner surface of the tubular body from the inside by an anode conductive member that makes electrical contact with the tubular body (b) Electrical contact with the tubular body. the anode conductive member, the outer surface of the tubular body is supported from the outside, the inner surface of the tubular body as engineering for electropolishing A method for producing a tubular body, which comprises the following steps (a) and (b) at least once.
(A) A step of supporting the inner surface of the tubular body from the inside by an anode conductive member that electrically contacts the tubular body and electrolytically polishing the outer surface of the tubular body.
(B) A step of electrolytically polishing the inner surface of the tubular body by supporting the entire outer surface of the tubular body from the outside by an anode conductive member that electrically contacts the tubular body. A method for producing a tubular body, which comprises the following steps (a) and (b) at least once.
(A) A step of electrolytically polishing the outer surface of the tubular body by supporting the entire inner surface of the tubular body from the inside by an anode conductive member that electrically contacts the tubular body.
(B) A step of electrolytically polishing the inner surface of the tubular body by supporting the entire outer surface of the tubular body from the outside by an anode conductive member that electrically contacts the tubular body. Wherein (a) Engineering enough to Oite, the anode conductive member for supporting the entire circumference of the inner surface of the tubular body, the manufacturing method of the tubular body according to claim 1 or 3 which is a single anode conductive member .. The method for manufacturing a tubular body according to claim 2 or 3, wherein in the step (b), the anode conductive member that supports the entire outer surface of the tubular body is a single anode conductive member. The tubular according to any one of claims 1 to 5 , wherein at least one of the anode conductive member used in the step (a) and the anode conductive member used in the step (b) is pipe-shaped. How to make a body. The claim that in step (a), at least a part of the tubular body is in contact with the anode conductive member on the inner surface of the tubular body in a state where the diameter is expanded by 0.1 mm or more and 2.0 mm or less from the reference inner diameter. The method for producing a tubular body according to any one of 1 to 6 . Claim that at least a part of the tubular body is in contact with the anode conductive member on the outer surface of the tubular body in a state where the diameter is reduced by 0.1 mm or more and 2.0 mm or less from the reference outer diameter in the step (b). Item 8. The method for producing a tubular body according to any one of Items 1 to 7 . A cathode is used in the step (a) or the step (b), and the cathode is on the inner surface and the outer surface of the tubular body opposite to the surface in contact with the anode conductive member. The method for manufacturing a tubular body according to any one of claims 1 to 8 , wherein the tubular body is arranged apart from the tubular body. The method for manufacturing a tubular body according to claim 9 , wherein in the step (a), the cathode has a shape curved along the outer peripheral surface shape of the tubular body. The method for producing a tubular body according to claim 9 or 10 , wherein in the step (b), the cathode has a curved shape, a rod shape, or a pipe shape. The method for producing a tubular body according to any one of claims 9 to 11 , wherein the cathode has a mesh shape or a punching shape in the step (a) or the step (b). The method for producing a tubular body according to any one of claims 9 to 12 , wherein in the step (a), the entire outer circumference of the tubular body is covered with the cathode of 1. The method for producing a tubular body according to any one of claims 9 to 12 , wherein in the step (a), the entire outer circumference of the tubular body is covered with the plurality of cathodes. The method for producing a tubular body according to any one of claims 9 to 14 , wherein in the step (b), the entire inner circumference of the tubular body is covered with the cathode of 1. The method for producing a tubular body according to any one of claims 9 to 14 , wherein in the step (b), the entire inner circumference of the tubular body is covered with the plurality of cathodes. The method for producing a tubular body according to any one of claims 1 to 16 , wherein the tubular body is a stent.

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