METHOD FOR PRODUCING BALLOON CATHETER

A method for producing a balloon catheter including preparing a balloon producing device (1), the device including a mold (10) into which a parison (50) is inserted, and a fixing member (30) for fixing the parison (50) outside the mold (10), the mold (10) provided with a rotation preventing portion (20) abutting the parison (50) so as to prevent rotation of the parison (50), disposing a part of the parison (50) in the mold (10), fixing a portion outside the mold (10) of the parison (50) with the fixing member (30), expanding the parison (50), removing the parison (50) from the mold (10), and cutting the parison (50).

TECHNICAL FIELD

The present invention relates to a method for producing a balloon catheter using a tubular parison.

BACKGROUND ART

As disclosed in Patent Documents 1 and 2, a balloon of a balloon catheter is produced by disposing a tubular parison in a mold and expanding a lumen of the parison by blow molding.

RELATED ART DOCUMENTS

Patent Documents

SUMMARY OF THE INVENTION

Technical Problem

However, since the parison rotates at the time of blow molding, a problem occurs that the balloon has an irregular shape, or a projection or a recess disposed on an outer surface of the balloon is twisted in a longitudinal direction, so that a desired balloon shape cannot be obtained, and there is room for improvement. Therefore, an object of the present invention is to provide a method for producing a balloon catheter capable of preventing rotation of a parison at the time of blow molding.

Solutions to the Problems

The gist of one embodiment of a method for producing a balloon catheter according to the present invention that can overcome the above problems is as follows. The method for producing a balloon catheter includes: preparing a balloon producing device, the device including a mold into which a tubular parison is inserted, and a fixing member for fixing the parison outside the mold, the mold including a first section for forming a straight tube portion and a tapered portion of a balloon and a second section present on both sides of the first section in a longitudinal direction, the second section provided with a rotation preventing portion abutting the parison so as to prevent rotation about a longitudinal axis direction of the parison; disposing a part of the parison in the longitudinal axis direction in the mold; fixing a portion disposed outside the mold of the parison with the fixing member; expanding the parison; removing the parison from the mold; and cutting the parison at a position corresponding to the second section. According to the present invention, the rotation of the parison may be prevented at a step of expanding the parison by a fixing member for fixing the parison outside a mold and a rotation preventing portion provided in the mold. Therefore, it is possible to produce a balloon and a projection and a recess disposed on an outer surface thereof into a desired shape.

Preferably, the rotation preventing portion is disposed in each of a distal second section present at a position corresponding to a distal side of the balloon with respect to the first section out of the second section and a proximal second section present at a position corresponding to a proximal side of the balloon with respect to the first section out of the second section.

Preferably, in the expanding the parison, a pressurizing member for introducing a fluid into the parison is connected to a first side or a second side in the longitudinal axis direction of the parison, and the rotation preventing portion is disposed in any one of a distal second section present at a position corresponding to a distal side of the balloon with respect to the first section and a proximal second section present at a position corresponding to a proximal side of the balloon with respect to the first section out of the second section, the section on the side on which the pressurizing member is connected to the parison.

Preferably, the fixing member includes a first fixing member for fixing a first side in the longitudinal axis direction of the parison, and a second fixing member for fixing a second side in the longitudinal axis direction of the parison, at least any one of the first fixing member and the second fixing member is movable in the longitudinal axis direction of the parison, and the rotation preventing portion is disposed in any one of a distal second section present at a position corresponding to a distal side of the balloon with respect to the first section and a proximal second section present at a position corresponding to a proximal side of the balloon with respect to the first section out of the second section, the section in which either the first fixing member or the second fixing member having a longer distance to move in the longitudinal axis direction of the parison is disposed.

Preferably, the fixing member includes the first fixing member for fixing a first side in the longitudinal axis direction of the parison and the second fixing member for fixing a second side in the longitudinal axis direction of the parison, and in the fixing a portion disposed outside the mold of the parison with the fixing member, the first fixing member fixes in such a way that a lumen cross-sectional shape of the parison is deformed as compared with the shape before fixing, and the second fixing member fixes in such a way that a deformation amount of the lumen cross-sectional shape of the parison is less than the deformation amount when fixing with the first fixing member.

Preferably, in the cutting the parison at a position corresponding to the second section, the parison is cut on a side of the straight tube portion with respect to a portion abutting the rotation preventing portion.

Preferably, in the cutting the parison at a position corresponding to the second section, the parison is cut at positions corresponding to the distal second section present at the position corresponding to the distal side of the balloon with respect to the first section and the proximal second section present at the position corresponding to the proximal side of the balloon with respect to the first section out of the second section.

Preferably, a first projection is disposed on an outer surface of the parison, and the rotation preventing portion is a first groove disposed on an inner wall surface of the mold and engaging with the first projection, or a second projection disposed on the inner wall surface of the mold and abutting the first projection.

Preferably, the first projection extends in the longitudinal axis direction of the parison, and the first groove or the second projection extends in the longitudinal direction of the mold.

Preferably, a first recess is disposed on an outer surface of the parison, and the rotation preventing portion is a third projection disposed on an inner wall surface of the mold and engaging with the first recess.

Preferably, the rotation preventing portion is an inner wall surface of the second section of the mold having surface roughness more than surface roughness of an inner wall surface of the first section of the mold, or an outer surface of the parison at the position corresponding to the second section having surface roughness more than surface roughness of the outer surface of the parison at a position corresponding to the first section. The surface roughness is arithmetic average roughness Ra in a reference length of a roughness curve on the inner wall surface of the mold or the outer surface of the parison, and the reference length is 0.1 mm.

Preferably, the rotation preventing portion is a first frictional resistance member provided on the inner wall surface of the second section and having frictional resistance more than frictional resistance of the inner wall surface of the first section, or a second frictional resistance member provided on an outer surface of the parison at the position corresponding to the second section and having frictional resistance more than frictional resistance of the outer surface of the parison at a position corresponding to the first section.

Preferably, out of the second section, the distal second section present at the position corresponding to the distal side of the balloon with respect to the first section includes a distal 2-1 section present on a side of the first section for forming a distal sleeve portion of the balloon, and a distal 2-2 section present at a position corresponding to a distal side of the balloon with respect to the distal 2-1 section, out of the second section, the proximal second section present at the position corresponding to the proximal side of the balloon with respect to the first section includes a proximal 2-1 section present on a side of the first section for forming a proximal sleeve portion of the balloon, and a proximal 2-2 section present at a position corresponding to a proximal side of the balloon with respect to the proximal 2-1 section, and the rotation preventing portion is disposed in at least any one of the distal 2-1 section and the proximal 2-1 section, the distal 2-2 section, and the proximal 2-2 section.

Preferably, the rotation preventing portion is disposed in the distal 2-2 section, the proximal 2-1 section, and the proximal 2-2 section, and is not disposed in the distal 2-1 section.

Preferably, in the expanding the parison, a pressurizing member for introducing a fluid into the parison is connected to a first side or a second side in the longitudinal axis direction of the parison, and the rotation preventing portion is disposed in any one of the distal 2-1 section and the proximal 2-1 section, the section on the side on which the pressurizing member is connected to the parison, the distal 2-2 section, and the proximal 2-2 section.

Preferably, the fixing member includes a first fixing member for fixing a first side in the longitudinal axis direction of the parison, and a second fixing member for fixing a second side in the longitudinal axis direction of the parison, at least any one of the first fixing member and the second fixing member is movable in the longitudinal axis direction of the parison, and the rotation preventing portion is disposed in any one of the distal 2-1 section and the proximal 2-1 section, the section in which either the first fixing member or the second fixing member having a longer distance to move in the longitudinal axis direction of the parison is disposed, the distal 2-2 section, and the proximal 2-2 section.

Advantageous Effects of the Invention

According to the method for producing, the rotation of the parison may be prevented at a step of expanding the parison. Therefore, it is possible to produce a balloon and a projection and a recess disposed on an outer surface thereof into a desired shape.

DESCRIPTION OF EMBODIMENTS

The present invention will be specifically explained below based on the following embodiments, however, the present invention is not restricted by the embodiments described below of course, and can be certainly put into practice after appropriate modifications within in a range meeting the gist of the above and the below, all of which are included in the technical scope of the present invention. In the drawings, hatching, a reference sign for a member may be omitted for convenience, and in such a case, the description and other drawings should be referred to. In addition, sizes of various members in the drawings may differ from the actual sizes thereof, since priority is given to understanding the features of the present invention.

One embodiment of a method for producing a balloon catheter according to the present invention includes: preparing a balloon producing device, the device including a mold into which a tubular parison is inserted, and a fixing member for fixing the parison outside the mold, the mold including a first section for forming a straight tube portion and a tapered portion of a balloon and a second section present on both sides of the first section in a longitudinal direction, the second section provided with a rotation preventing portion abutting the parison so as to prevent rotation about a longitudinal axis direction of the parison; disposing a part of the parison in the longitudinal axis direction in the mold; fixing a portion disposed outside the mold of the parison with the fixing member; expanding the parison; removing the parison from the mold; and cutting the parison at a position corresponding to the second section. According to the present invention, the rotation of the parison may be prevented at a step of expanding the parison by a fixing member for fixing the parison outside a mold and a rotation preventing portion provided in the mold. Therefore, it is possible to produce a balloon and a projection and a recess disposed on an outer surface thereof into a desired shape.

A parison and a balloon producing device used in the above-described producing method are described with reference toFIGS. 1 to 4.FIG. 1is a perspective view of a parison according to one embodiment of the present invention, andFIG. 2is a side view of a balloon according to one embodiment of the present invention.FIG. 3is a cross-sectional view (partial side view) of a balloon producing device according to one embodiment of the present invention, andFIG. 4is a cross-sectional view taken along line Iv-Iv of the balloon producing device illustrated inFIG. 3. Note that,FIG. 3illustrates a state in which a parison50before expansion is disposed in a mold10.

A balloon catheter is a medical instrument used in angioplasty (PTA, PTCA and the like) for dilating a stenosis part performed mainly in treatment of the stenosis part of the blood vessel. It is known that various diseases occur when the blood vessel, which is a flow path for circulating blood in a body, becomes stenosed and blood circulation becomes sluggish. Especially when the coronary artery that supplies blood to the heart becomes stenosed, this might cause severe diseases such as angina pectoris and myocardial infarction. Angioplasty is widely performed because this is minimally invasive therapy that does not require thoracotomy such as bypass surgery.

The balloon catheter includes a shaft and a balloon provided outside the shaft. The balloon catheter has a proximal side and a distal side, the balloon is provided on a distal side of the shaft, and a hub is provided on a proximal side of the shaft. Note that a proximal side of the balloon refers to a side near a user (operator) in an extending direction of the balloon catheter, and a distal side refers to a side in a direction opposite to the proximal side (that is, a direction toward a treated target).

As illustrated inFIG. 1, the parison50is a tubular resin mass fabricated by extrusion molding. The parison50includes a first end50A and a second end50B, and extends in a longitudinal axis direction x1from the first end50A toward the second end50B. As illustrated inFIG. 3, when the parison50is disposed in the mold10, at least any one of a first side and a second side in the longitudinal axis direction x1is exposed from the mold10. It is especially preferable that the first side and the second side of the parison50in the longitudinal axis direction x1are exposed from the mold10. The balloon for the balloon catheter may be produced by introducing a fluid such as air, nitrogen, or water into a lumen51of the parison50and expanding the parison50.

FIG. 2illustrates a balloon60formed by expanding the parison50. The balloon60includes a straight tube portion61, a tapered portion62disposed on both sides of the straight tube portion61with an outer diameter decreasing toward an end side in the longitudinal axis direction x1, a sleeve portion63disposed on the end side in the longitudinal axis direction x1with respect to the tapered portion62and connected to the shaft of the balloon catheter, and a sleeve outer portion64disposed on the end side in the longitudinal axis direction x1with respect to the sleeve portion63and cut at a step described later. Since the sleeve outer portion64is an unnecessary portion as a final product, this is cut. The tapered portion62disposed on the distal side with respect to the straight tube portion61is referred to as a distal tapered portion62D, and the tapered portion62disposed on the proximal side with respect to the straight tube portion61is referred to as a proximal tapered portion62P. The sleeve portion63disposed on the distal side with respect to the distal tapered portion62D is referred to as a distal sleeve portion63D, and the sleeve portion63disposed on the proximal side with respect to the proximal tapered portion62P is referred to as a proximal sleeve portion63P. Furthermore, the sleeve outer portion64disposed on the distal side with respect to the distal sleeve portion63D is referred to as a distal sleeve outer portion64D, and the sleeve outer portion64disposed on the proximal side with respect to the proximal sleeve portion63P is referred to as a proximal sleeve outer portion64P.

A first projection53(refer toFIG. 1) projecting radially outward or a recess (not illustrated) recessed radially inward may be disposed on the outer surface of the parison50. At least a part of the projection or recess preferably remains on the outer surface of the balloon60even after a step of expanding the parison50.

As illustrated inFIG. 1, a cross-sectional shape of the parison50in a direction perpendicular to the longitudinal axis direction x1may be substantially uniform in the longitudinal axis direction x1. Accordingly, productivity of the parison50may be enhanced. The cross-sectional shape of the parison50in the direction perpendicular to the longitudinal axis direction x1may differ depending on a position in the longitudinal axis direction x1. InFIG. 3, an outer diameter of a part (for example, a portion corresponding to the straight tube portion of the balloon) of the parison50in the longitudinal axis direction x1is larger than that of a part other than this part. In order to make the cross-sectional shape of the parison differ in the longitudinal axis direction x1in this manner, blow molding may be performed using another mold in advance.

Examples of a material forming the parison50include, for example, a polyolefin-based resin such as polyethylene, polypropylene, and an ethylene-propylene copolymer, a polyester-based resin such as polyethylene terephthalate and polyester elastomer, a polyurethane-based resin such as polyurethane and polyurethane elastomer, a polyphenylenesulfide-based resin, a polyamide-based resin such as polyamide and polyamide elastomer, a fluorine-based resin, a silicone-based resin, and natural rubber such as latex rubber. It is possible to use only one of them or two or more of them. Among them, the polyamide-based resin, polyester-based resin, and polyurethane-based resin are suitably used. It is especially preferable to use an elastomer resin from the viewpoint of thinning and flexibility of the balloon. For example, examples of a material suitable for the parison50among the polyamide-based resins include nylon 12, nylon 11 and the like, and nylon 12 is suitably used because this may be relatively easily molded at the time of blow molding. From the viewpoint of thinning and flexibility of the balloon, polyamide elastomer such as polyether ester amide elastomer and polyamide ether elastomer are preferably used. Among them, polyether ester amide elastomer is preferably used from the viewpoint of high yield strength and excellent dimensional stability of the balloon.

The balloon producing device1includes the mold10and a fixing member30. The parison50is inserted into the mold10. Specifically, a part of the parison50in the longitudinal axis direction x1is disposed in the mold10. As illustrated inFIG. 3, the mold10has a longitudinal direction x2corresponding to the longitudinal axis direction x1of the parison50. In order to easily dispose the parison50in the mold10, the longitudinal direction x2of the mold10preferably coincides with the longitudinal axis direction x1of the parison50. The mold10includes a first section11for forming the straight tube portion61and the tapered portion62of the balloon60, and a second section12present on both sides of the first section11in the longitudinal direction x2. Out of the parison50, a portion corresponding to the first section11of the mold10forms the straight tube portion61and the tapered portion62of the balloon60, and a portion corresponding to the second section12of the mold10forms the sleeve portion63and the sleeve outer portion64of the balloon60.

The mold10may be formed of one member or may be formed of a plurality of members. For example, the mold10may be formed of a plurality of half-cut bodies, or a plurality of mold members may be connected to each other in the longitudinal direction x2. It is especially preferable that the mold10is formed of a plurality of mold members having different lumen cross-sectional shapes. InFIG. 3, the mold10includes a first mold10A, a second mold10B, a third mold10C, a fourth mold10D, a fifth mold10E, and a sixth mold10F in this order from the proximal side. As illustrated inFIG. 3, adjacent metal mold members may be engaged with each other to be connected. Although not illustrated, magnets may be attached to each of the adjacent mold members, and they may attract each other to be connected.

The lumen cross-sectional shape of the mold10may have a circular shape, an elliptical shape, a polygonal shape, or a shape obtained by combining these shapes.

The fixing member30fixes the parison50outside the mold10. By fixing a portion disposed outside the mold10out of the parison50with the fixing member30, it is possible to prevent rotation of the parison50at the step of expanding the parison50. It is preferable that the parison50fixed by the fixing member30cannot rotate and cannot move in the longitudinal axis direction x1.

The fixing member30preferably fixes at least one side in the longitudinal axis direction x1of the parison50, and more preferably includes a first fixing member31for fixing the first side in the longitudinal axis direction x1of the parison50and a second fixing member35for fixing the second side in the longitudinal axis direction x1of the parison50as illustrated inFIG. 3. Accordingly, it is difficult for the parison50to rotate even when the parison50is expanded. A fixing position of the parison50is not especially limited, but it is preferable to fix a range within 10 cm from the first end50A or the second end50B in the longitudinal axis direction x1of the parison50, and it is more preferable to fix a range within 8 cm, and still more preferable to fix a range within 5 cm. A fixing mechanism of the first fixing member31and that of the second fixing member35may be the same as or different from each other.

The fixing member30preferably fixes a position corresponding to the sleeve outer portion64of the balloon60out of the parison50. The sleeve outer portion64of the balloon60is a portion that is cut off before being fixed to the shaft and is not used as the final product. Therefore, by fixing the sleeve outer portion64with the fixing member30, an influence on a shape and a quality of a product balloon may be eliminated.

The fixing member30includes a plurality of chuck pieces, and may grip the parison50by the plurality of chuck pieces. It is also possible that the fixing member30includes fastening members facing each other and fastens to fix the parison50by these fastening members.

Note that, inFIG. 3, the first fixing member31that includes two fastening members32facing each other and fastens to fix a distal end of the parison50by the fastening members32, and the second fixing member35that includes two chuck pieces36and grips a proximal end of the parison50by the chuck pieces36are illustrated. The fastening members32include teeth33that mesh with each other.

It is preferable that at least any one of the first fixing member31and the second fixing member35is movable in the longitudinal axis direction x1of the parison50. When at least any one of the first fixing member31and the second fixing member35moves, the parison50may be extended in the longitudinal axis direction x1.

In a case where the fixing member30includes the first fixing member31for fixing the first side in the longitudinal axis direction x1of the parison50and the second fixing member35for fixing the second side in the longitudinal axis direction x1of the parison50, at a step of fixing a portion disposed outside the mold10of the parison50with the fixing member30, the first fixing member31preferably fixes in such a way that a lumen cross-sectional shape of the parison50is deformed as compared with the shape before fixing, and the second fixing member35preferably fixes in such a way that a deformation amount of the lumen cross-sectional shape of the parison50is less than that when fixing with the first fixing member31. Accordingly, the parison50may be fixed in a state in which the lumen51of the parison50is secured by the second fixing member35, that is, in a state in which the lumen51of the parison50is not completely crushed, and the fluid may be introduced thereinto, so that the step of expanding the parison50may be efficiently performed.

As illustrated inFIG. 3, the second section12of the mold10is provided with a rotation preventing portion20that abuts the parison50so as to prevent rotation of the parison50about the longitudinal axis direction x1. The rotation preventing portion20includes a portion that locks the parison50or a portion that generates frictional resistance between the same and the parison50, and is formed on an inner wall surface19of the mold10. By providing the rotation preventing portion20in addition to the fixing member30in this manner, the parison50abuts the rotation preventing portion20at the step of expanding the parison50, so that the rotation of the parison50may be further prevented.

One or a plurality of the rotation preventing portions20may be provided in the mold10; it is preferable to provide a plurality of them in order to enhance a rotation preventing effect of the parison50.

In the rotation preventing portion20, the parison50is preferably not fixed with respect to the mold10in the longitudinal direction x2. That is, the parison50preferably moves in the longitudinal direction x2with respect to the mold10. Accordingly, the parison50is easily inserted into the mold10.

The rotation preventing portion20may be provided, for example, in a position hereinafter described.

The rotation preventing portion20is preferably disposed in either a distal second section13present at a position corresponding to the distal side of the balloon with respect to the first section11out of the second section12(hereinafter, simply referred to as a “distal second section”) or a proximal second section16present at a position corresponding to the proximal side of the balloon with respect to the first section11out of the second section12(hereinafter, simply referred to as a “proximal second section”). By providing one rotation preventing portion20in this manner, the rotation preventing effect of the parison50may be obtained.

The rotation preventing portion20is preferably disposed in each of the distal second section13and the proximal second section16. By disposing the rotation preventing portion20in each of the distal second section13and the proximal second section16, the rotation preventing effect of the parison50may be further enhanced.

At the step of expanding the parison50, a pressurizing member40for introducing a fluid into the parison50is preferably connected to the first side or the second side in the longitudinal axis direction x1of the parison50. Accordingly, it becomes possible to expand the parison50to mold the balloon. InFIG. 3, the pressurizing member40is connected to the proximal end of the parison50in the longitudinal axis direction x1via the second fixing member35, but the pressurizing member40may also be connected to the distal end of the parison50in the longitudinal axis direction x1.

In a case where the fixing member30includes the first fixing member31and the second fixing member35, the first fixing member31fixes in such a way that a lumen cross-sectional shape of the parison50is deformed as compared with that before fixing, and the second fixing member35fixes in such a say that a deformation amount of the lumen cross-sectional shape of the parison50is less than that when fixing with the first fixing member31, it is preferable that the pressurizing member40is disposed on the first side or the second side in the longitudinal axis direction x1of the parison50, the side of the second fixing member35. Accordingly, it becomes possible to introduce the fluid into the parison50from the side of the second fixing member35while narrowing the lumen51of the parison50by the first fixing member31.

In a case where the pressurizing member40is connected to the first side or the second side in the longitudinal axis direction x1of the parison50, the rotation preventing portion20is preferably disposed in any one of the distal second section13and the proximal second section16, the section on the side on which the pressurizing member40is connected to the parison50. On the side of the parison50to which the pressurizing member40is connected, rotation and positional displacement of the parison50are more likely to occur as compared to the side to which the pressurizing member40is not connected due to a reaction force at the time of fluid introduction into the lumen51of the parison50. Therefore, the rotation of the parison50may be efficiently prevented by providing the rotation preventing portion20in either the distal second section13or the proximal second section16, the section on the side on which the pressurizing member40is connected to the parison50.

The fixing member30includes the first fixing member31that fixes the first side in the longitudinal axis direction x1of the parison50and the second fixing member35that fixes the second side in the longitudinal axis direction x1of the parison50, and at least any one of the first fixing member31and the second fixing member35is movable in the longitudinal axis direction x1of the parison50. In this case, the rotation preventing portion20is preferably disposed in any one of the distal second section13and the proximal second section16in which either the first fixing member31or the second fixing member35having a longer distance to move in the longitudinal axis direction x1of the parison50is disposed. On the side in the longitudinal axis direction x1of the parison50on which the fixing member30having the longer distance to move is disposed, rotational deviation due to extension of the parison50at the time of blow molding is likely to occur as compared to the side on which the fixing member30having a shorter distance to move is disposed. Therefore, the rotation of the parison50may be efficiently prevented by providing the rotation preventing portion20at the above-described position.

The distal second section13may include a distal 2-1 section14present on a side of the first section11for forming the distal sleeve portion63D of the balloon, and a distal 2-2 section15present at a position corresponding to the distal side of the balloon with respect to the distal 2-1 section14. The proximal second section16may include a proximal 2-1 section17present on a side of the first section11for forming the proximal sleeve portion63P of the balloon, and a proximal 2-2 section18present at a position corresponding to the proximal side of the balloon with respect to the proximal 2-1 section17.

In a case where the distal second section13includes the distal 2-1 section14and the distal 2-2 section15, and the proximal second section16includes the proximal 2-1 section17and the proximal 2-2 section18, it is preferable that the rotation preventing portion20is disposed in the distal 2-2 section15and the proximal 2-2 section18, and is not disposed in the distal 2-1 section14and the proximal 2-1 section17. Portions corresponding to the distal 2-2 section15and the proximal 2-2 section18of the parison50are at positions corresponding to an outer side of the sleeve portion63of the balloon60(that is, the sleeve outer portion64of the balloon60), so that they are portions that are cut off before being fixed to the shaft and are not used as the final product. By disposing the rotation preventing portion20in the sections, an influence on the shape and quality of the product balloon may be eliminated.

In a case where the distal second section13includes the distal 2-1 section14and the distal 2-2 section15, and the proximal second section16includes the proximal 2-1 section17and the proximal 2-2 section18, it is preferable that the rotation preventing portion20is disposed in at least any one of the distal 2-1 section14and the proximal 2-1 section17, and in the distal 2-2 section15and the proximal 2-2 section18. By providing the rotation preventing portion20in the distal 2-2 section15and the proximal 2-2 section18, an influence on the shape and quality of the product balloon may be eliminated. By disposing the rotation preventing portion20also in at least any one of the distal 2-1 section14and the proximal 2-1 section17, the rotation preventing effect of the parison50is enhanced.

In the longitudinal direction x2of the mold10, the distal 2-2 section15is preferably longer than the distal 2-1 section14. Accordingly, the rotation preventing portion20of the mold10easily abuts the parison50in a wide range. For a similar reason, in the longitudinal direction x2of the mold10, the proximal 2-2 section18is preferably longer than the proximal 2-1 section17.

It is preferable that the rotation preventing portion20is disposed in the distal 2-2 section15, the proximal 2-1 section17, and the proximal 2-2 section18, and is not disposed in the distal 2-1 section14. By not disposing the rotation preventing portion20in the distal 2-1 section14for forming the distal sleeve portion63D of the balloon60, slipperiness of the distal sleeve portion63D of the balloon60is appropriately secured, so that crossability of the balloon at a lesion may be enhanced.

At the step of expanding the parison50, it is preferable that the pressurizing member40for introducing the fluid into the parison50is connected to the first side or the second side in the longitudinal axis direction x1of the parison50, and the rotation preventing portion20is disposed in any one of the distal 2-1 section14and the proximal 2-1 section17, the section on the side on which the pressurizing member40is connected to the parison50, the distal 2-2 section15, and the proximal 2-2 section18. By providing the rotation preventing portion20in the distal 2-2 section15and the proximal 2-2 section18, an influence on the shape and quality of the product balloon may be eliminated. On the side of the parison50to which the pressurizing member40is connected, rotation and positional displacement of the parison50are more likely to occur as compared to the side to which the pressurizing member40is not connected due to a reaction force at the time of fluid introduction into the lumen51of the parison50. Therefore, the rotation preventing effect of the parison50may be further enhanced by providing the rotation preventing portion20in either the distal 2-1 section14or the proximal 2-1 section17, the section on the side on which the pressurizing member40is connected to the parison50.

In a case where the fixing member30includes the first fixing member31for fixing the first side in the longitudinal axis direction x1of the parison50, and the second fixing member35for fixing the second side in the longitudinal axis direction x1of the parison50, and at least any one of the first fixing member31and the second fixing member35is movable in the longitudinal axis direction x1of the parison50, the rotation preventing portion20is preferably disposed in any one of the distal 2-1 section14and the proximal 2-1 section17, the section in which either the first fixing member31or the second fixing member35having a longer distance to move in the longitudinal axis direction x1of the parison50is disposed, the distal 2-2 section15, and the proximal 2-2 section18. By providing the rotation preventing portion20in the distal 2-2 section15and the proximal 2-2 section18, an influence on the shape and quality of the product balloon may be reduced. On the side in the longitudinal axis direction x1of the parison50on which the fixing member30having the longer distance to move is disposed, rotational deviation due to extension of the parison50at the time of blow molding is likely to occur as compared to the side on which the fixing member30having a shorter distance to move is disposed. Therefore, by providing the rotation preventing portion20also in any one of the distal 2-1 section14and the proximal 2-1 section17, the section in which either the first fixing member31or the second fixing member35having a longer distance to move is disposed, the rotation preventing effect of the parison50may be further enhanced.

Hereinafter, a specific aspect of the rotation preventing portion20is described.

As illustrated inFIG. 4, it is preferable that the first projection53is disposed on the outer surface of the parison50, and the rotation preventing portion20is a first groove21disposed on the inner wall surface19of the mold10and engaging with the first projection53. As illustrated inFIG. 5, it is preferable that the first projection53is disposed on the outer surface of the parison50, and the rotation preventing portion20is a second projection22disposed on the inner wall surface19of the mold10and abutting the first projection53. The rotation of the parison50may be prevented by the engagement between the first projection53and the first groove21or the abutment between the first projection53and the second projection22.

It is preferable that the first projection53extends in the longitudinal axis direction x1of the parison50, and the first groove21or the second projection22extends in the longitudinal direction x2of the mold10. By extending the first projection53and the first groove21or the second projection22in this manner, the rotation preventing effect of the parison50is enhanced. Note that, in order to prevent positional displacement of the parison50in the longitudinal axis direction x1, the first projection53may extend in a circumferential direction of the parison50.

The first projection53is preferably disposed at least in a section forming the sleeve outer portion64of the balloon60of the parison50, and more preferably disposed in a section forming the sleeve outer portion64and the sleeve portion63of the balloon60.

The first projection53may be disposed over an entire parison50in the longitudinal axis direction x1. In this case, the first groove21or the second projection22is preferably disposed in the first section11and the second section12of the mold10.

One or a plurality of the first projections53may be disposed on the outer surface of the parison50. In order to enhance the rotation preventing effect of the parison50, it is preferable that a plurality of first projections53is disposed apart from each other in a circumferential direction p.FIGS. 4 and 5illustrate an example in which three first projections53extending in the longitudinal axis direction x1of the parison50are disposed at regular intervals in the circumferential direction p.

In a cross-section perpendicular to the longitudinal axis direction x1of the parison, the first projection53may be disposed to be narrowed radially outward. A tip of the first projection53may be sharp or rounded.

Although not illustrated, both the first groove21engaging with the first projection53of the parison50and the second projection22abutting the first projection53may be disposed on the inner wall surface19of the mold10. For example, the first groove21may be disposed in any one of the distal second section13and the proximal second section16, and the second projection22may be disposed in the other.

A depth of the first groove21and a height of the second projection22may be the same in the longitudinal direction x2of the mold10, or may differ depending on a position in the longitudinal direction x2.

As illustrated inFIG. 6, it is preferable that a first recess54is disposed on the outer surface of the parison50, and the rotation preventing portion20is a third projection23disposed on the inner wall surface19of the mold10and engaging with the first recess54. When the first recess54of the parison50and the third projection23of the mold10engage with each other, the rotation of the parison50may be prevented.

The first recess54preferably extends in the longitudinal axis direction x1of the parison50. In this case, the third projection23preferably extends in the longitudinal direction x2of the mold10. By extending the first recess54and the third projection23in this manner, the rotation preventing effect of the parison50is enhanced.

One or a plurality of the first recesses54may be disposed on the outer surface of the parison50. Similarly, one or a plurality of the third projections23may be disposed on the inner wall surface19of the mold10. As for the number and shapes of the first recesses54and the third projections23, a configuration example of the first grooves21or the first projections53may be referred to.

The parison including the first projection53or the first recess54may be extrusion molded from a single material or may be molded by co-extrusion using a plurality of materials. The parison including the first projection53may be molded by bonding or welding a linear resin mass to a tubular or polygonal tubular resin mass. The parison including the first recess54may be molded by cutting out the outer surface of the cylindrical or polygonal tubular resin mass by a method such as cutting or peeling.

The rotation preventing portion20is preferably the inner wall surface19of the second section12of the mold10having surface roughness more than surface roughness of the inner wall surface19of the first section11of the mold10, or the outer surface of the parison50at the position corresponding to the second section12having surface roughness more than surface roughness of the outer surface of the parison50at a position corresponding to the first section11. The surface roughness is arithmetic average roughness Ra in a reference length of a roughness curve on the inner wall surface19of the mold10or the outer surface of the parison50, and the reference length is 0.1 mm. The rotation of the parison50may also be prevented by increasing the surface roughness of the inner wall surface19of the mold10or the outer surface of the parison50in this manner.

The above-described arithmetic average roughness Ra corresponds to the arithmetic average roughness Ra defined in JIS B 0601 (2001), and is measured in accordance with JIS B 0633 (2001). For the measurement, a measuring instrument (for example, a laser microscope VK-9510 manufactured by KEYENCE CORPORATION) defined in JIS B 0651 (2001) is used.

Examples of a method for increasing the surface roughness of the inner wall surface19of the mold10and the outer surface of the parison50include a method for mechanically or chemically roughening these surfaces; there are, for example, a method using etching, blasting, a wire brush, or sandpaper.

The rotation preventing portion20is preferably a first frictional resistance member provided on the inner wall surface19of the second section12and having frictional resistance more than frictional resistance of the inner wall surface19of the first section11, or a second frictional resistance member provided on the outer surface of the parison50at the position corresponding to the second section12and having frictional resistance more than frictional resistance of the outer surface of the parison50at a position corresponding to the first section11. The rotation of the parison50may also be prevented by providing the frictional resistance member on the inner wall surface19of the mold10or the outer surface of the parison50in this manner.

The first frictional resistance member or the second frictional resistance member may be made of an elastic material such as silicone rubber or polyamide-based resin, for example.

The first frictional resistance member or the second frictional resistance member may be disposed in a layered manner, or may be disposed linearly or in a net shape. The first frictional resistance member may extend in at least any one of the longitudinal direction x2of the mold10and the circumferential direction of the parison50. The second frictional resistance member may extend in at least any one of the longitudinal axis direction x1of the parison50and the circumferential direction of the parison50.FIG. 7illustrates an example in which two layered first frictional resistance members24are disposed at regular intervals in the circumferential direction, andFIG. 8illustrates an example in which four linear first frictional resistance members24are disposed at regular intervals in the circumferential direction. One first frictional resistance member and one second frictional resistance member may be disposed or a plurality of the first frictional resistance members and a plurality of the second frictional resistance members may be disposed.

Another example of a case where the first projection53is disposed on the outer surface of the parison50and the rotation preventing portion20is the first groove21and the second projection22of the mold10is described with reference toFIGS. 9 to 16.FIG. 9is a cross-sectional view of the mold10according to another embodiment of the present invention, andFIGS. 10 to 16are cross-sectional views of the mold illustrated inFIG. 9. For example, as illustrated inFIGS. 9 to 11, it is preferable that the first groove21is disposed in the proximal 2-2 section18, and the second projection22is disposed in the proximal 2-1 section17. Accordingly, the tip of the first projection53is not easily crushed in the proximal 2-1 section17, that is, on a side close to the straight tube portion61and the tapered portion62of the balloon60.

As illustrated inFIGS. 9 to 11andFIGS. 15 and 16, it is preferable that the first groove21is disposed in the distal 2-2 section15and the proximal 2-2 section18, the second projection22is disposed in the proximal 2-1 section17, and the rotation preventing portion20is not disposed in the distal 2-1 section14. By not disposing the rotation preventing portion20in the distal 2-1 section14for forming the distal sleeve portion63D of the balloon60, the tip of the first projection53may be crushed, and slipperiness of the distal sleeve portion63D of the balloon60is appropriately secured, so that crossability of the balloon at the lesion may be enhanced.

In a case where the first groove21is disposed in each of the distal 2-2 section15and the proximal 2-2 section18, depths of these grooves may be the same as or different from each other.

A groove or a projection may be disposed separately from the rotation preventing portion20on the inner wall surface19of the mold10. For example, as illustrated inFIGS. 12 and 13, a second groove25may be disposed on the inner wall surface19of the first section11of the mold10. By disposing the second groove25in this manner, it is possible to dispose a projection at a position corresponding to the straight tube portion61and the tapered portion62of the balloon60after the parison50is expanded.

The step of expanding the parison50is described. The parison50is expanded by introducing a fluid such as air, nitrogen, or water into the lumen51of the parison50while heating the parison50at glass transition temperature of resin or more. Note that the parison50may be extended in the longitudinal axis direction x1before the step of expanding the parison50. The step of expanding the parison50may be performed only once or a plurality of times. In a case where the step of expanding is performed a plurality of times, it is preferable to use different molds for each expansion.

A step of cutting the parison50is described. At the step of cutting the parison50at the position corresponding to the second section12, the parison50is preferably cut on a side of the straight tube portion61with respect to the portion abutting the rotation preventing portion20. Accordingly, it is possible to exclude the portion abutting the rotation preventing portion20of the parison50, so that the shape and quality of the product balloon may be easily ensured.

At the step of cutting the parison50at the position corresponding to the second section12, the parison50is preferably cut at positions corresponding to the distal second section13and the proximal second section16. The rotation preventing portion20is provided in at least any one of the distal second section13and the proximal second section16. By cutting the parison50at the positions corresponding to the sections, it is possible to exclude the portion abutting the rotation preventing portion20of the parison50, so that the shape and quality of the product balloon may be easily ensured.

At the step of cutting the parison50at the position corresponding to the second section12, the parison50may be cut at a position corresponding to the proximal side with respect to a proximal end of the distal 2-2 section15and a position corresponding to the distal side with respect to a distal end of the proximal 2-2 section18. The parison50may also be cut at a position corresponding to a boundary between the distal 2-1 section14and the distal 2-2 section15and a position corresponding to a boundary between the proximal 2-1 section17and the proximal 2-2 section18.

The parison50is preferably cut in the direction perpendicular to the longitudinal axis direction x1, but the parison50may also be cut obliquely with respect to the longitudinal axis direction x1.

When cutting the parison50, a blade such as a knife, a razor, or scissors, or a heat source such as a laser, an ultrasonic wave, or a heater may be used.

The cut parison50may be used as the balloon for the balloon catheter. The method for producing the balloon catheter of the present invention preferably further includes a step of fixing the cut parison on the distal side of the shaft.

The shaft includes the distal side and the proximal side. The shaft is usually provided therein with a flow path for the fluid supplied into the balloon and an insertion path for a wire that guides progress of the shaft. For obtaining an excellent fluid flow, the flow path of the fluid preferably extends in a longitudinal direction of the shaft. The shaft may have a coaxial structure formed at least of a double tube, or may have a multi-lumen structure including a plurality of lumens.

The shaft preferably has flexibility. Accordingly, the shaft may be deformed along a body cavity shape. The shaft preferably has elasticity for maintaining a shape thereof. The shaft is preferably made of resin, metal or a combination thereof. For example, the shaft may be a resin tube; a metal tube; a hollow body formed by disposing a single wire or a plurality of wire materials or twisted wire materials in a predetermined pattern; the hollow body at least any one of an inner surface and an outer surface of which is coated with resin; or a combination thereof or that obtained by connecting them in the longitudinal direction.

By using a resin as a component of the shaft, flexibility and elasticity are easily imparted to the shaft. By using metal as a component of the shaft, it is possible to improve deliverability of the balloon catheter. Examples of the resin forming the shaft include a polyamide-based resin, a polyester-based resin, a polyurethane-based resin, a polyolefin-based resin, a fluorine-based resin, a vinyl chloride-based resin, a silicone-based resin, natural rubber, synthetic rubber and the like. It is possible to use only one of them or two or more of them. As the resin forming the shaft, either a thermoplastic resin or a thermosetting resin may be used, and among them, a thermoplastic resin is preferably used. Examples of the metal forming the shaft include stainless steel such as SUS304 and SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, a Ni—Ti alloy, a Co—Cr alloy, or a combination thereof. Note that the shaft may have a laminated structure made of different materials or the same material.

This application claims the benefit of the priority date of Japanese patent application No. 2019-55202 filed on Mar. 22, 2019. All of the contents of the Japanese patent application No. 2019-55202 filed on Mar. 22, 2019 are incorporated by reference herein.

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