Medical multi-lumen tube and method for producing the same

A medical multi-lumen tube includes a plurality of inner layer tubes and an outer layer tube covering the plurality of inner layer tubes. The outer layer tube has a first region and a second region placed in the axial direction of the outer layer tube and formed of resins having properties different from each other, and the resin of one of the regions enters the other region, so as to form a wave pattern in a joint part between the first region and the second region.

TECHNICAL FIELD

The disclosed embodiments relate to a medical multi-lumen tube and a method for producing the same.

BACKGROUND

Conventionally, a medical multi-lumen tube including a plurality of lumens has been known. Multi-lumen tubes are used for catheters, endoscopes, etc., and are inserted into tubular organs of a human body such as blood vessels, digestive tracts, and ureters, and body tissues. For example, Patent Literature 1 discloses a multi-lumen tube including a first lumen inside an inner tube and a second lumen between the outside of the inner tube and the inside of the outer tube. Further, for example, Patent Literature 2 discloses a multi-lumen tube having four lumens. Further, for example, Patent Literature 3 discloses a multi-lumen tube in which a groove portion is formed on the outer peripheral surface of a tubular body forming a main lumen and a hollow tube forming a sub-lumen is disposed in the groove portion.

It is known that a multi-lumen tube is formed by joining resins having different properties to each other in an outer layer. In such a multi-lumen tube, if the joint strength of the joint part is not sufficient, the outer layer may break at the joint part in the blood vessel or the branched blood vessel portions of a winding and complicated route. Further, such a multi-lumen tube is problematic in that a rigidity gap is easily formed leading to a change in flexural rigidity in the vicinity of the joint part, and stress is concentrated in the vicinity of the joint part in the blood vessel or the branched blood vessel portions, and kinking or breakage is likely to occur.

CITATION LIST

Patent Literature

SUMMARY

The disclosed embodiments have been devised to address the above-mentioned problems, and an object thereof is to provide a technique for suppressing the occurrence of breakage or kinking in a multi-lumen tube.

The disclosed embodiments include the following embodiments.

(1) According to one of the disclosed embodiments, a medical multi-lumen tube is provided. The multi-lumen tube includes a plurality of inner layer tubes and an outer layer covering the plurality of inner layer tubes. The outer layer has a first region and a second region formed of resins having different properties from each other and placed in the axial direction of the outer layer. In the joint part between the first region and the second region, the resin of one of the regions enters the other region, so as to form a wave pattern.

According to this configuration, the joint area between the resin of the first region and the resin of the second region of the outer layer can be increased, so that the joint strength at the joint part between the first region and the second region can be improved. Further, between the first region and the second region of the outer layer, the switching from the resin constituting one of the regions to the resin constituting the other region is made gradual, so that the change in flexural rigidity can be gradual. As a result, a rigidity gap of flexural rigidity in the vicinity of the joint part is less likely to occur, so that the occurrence of kinking and breakage can be suppressed.

(2) In the multi-lumen tube of the above embodiment, the plurality of inner layer tubes may include a first inner layer tube having a relatively large outer diameter and a second inner layer tube having a relatively small outer diameter. When the outer layer is divided into a side where the first inner layer tube is located and a side where the second inner layer tube is located along the circumferential direction of the outer layer, the wave pattern may be formed on the side where at least the second inner layer tube is located. According to this configuration, the crush resistance of the second inner layer tube can be further improved. Further, the misalignment of the second inner layer tube at the time of forming the outer layer can be suppressed.

(3) In the outer layer of the multi-lumen tube of the above embodiment, the resin of one of the regions may enter the other region on both sides of the second inner layer tube in the circumferential direction of the outer layer, so that a wave pattern may be formed by the resin having entered on both sides of the second inner layer tube. According to this configuration, the displacement of the second inner layer tube at the time of forming the outer layer can be further suppressed.

(4) In the multi-lumen tube of the above embodiment, the outer layer may have a third region formed of a resin having different properties from those of the resin of the second region, wherein the second region and the third region are connected at a second joint part differing from the above joint part, and in the second joint part, the resin of the second region or the third region enters the other region, so that a wave pattern may be formed. According to this configuration, the joint area between the resin of the second region and the resin of the third region of the outer layer can be increased, so that the joint strength at the second joint part can be improved. Further, the switching from the resin constituting one of the regions to the resin constituting the other region is made gradual between the second region and the third region of the outer layer, so that the rigidity gap of the flexural rigidity in the vicinity of the second joint part can be made hard to occur.

(5) According to another embodiment of the disclosed embodiments, a catheter is provided. This catheter includes the multi-lumen tube of the above embodiment, wherein the first region of the multi-lumen tube is closer to the distal end side of the catheter than the second region, and the hardness of the resin of the first region is lower than the hardness of the resin of the second region. According to this configuration, the rigidity can be gradually increased from the distal end to the proximal end of the catheter, so that the passage of the catheter through a tubular organ such as a blood vessel can be improved.

The disclosed embodiments can be realized in various aspects, for example, in various embodiments, such as a catheter including a multi-lumen tube, a balloon catheter, an endoscope, an apparatus for producing a multi-lumen tube, and a method for producing a multi-lumen tube.

DETAILED DESCRIPTION OF EMBODIMENTS

First Embodiment

The overall configuration of a catheter1including a multi-lumen tube10of the first embodiment will be described with reference toFIGS.1and2.FIG.1is an explanatory view illustrating the appearance of the catheter1.FIG.2is an explanatory view illustrating a cross section taken along the line A-A inFIG.1in the multi-lumen tube10. Hereinafter, the left side (distal tip15side) ofFIG.1is referred to as the “distal end side” of the catheter1, and the right side (connector17side) ofFIG.1is referred to as the “proximal end side” of the catheter1. The distal end side of the catheter1is the side (distal side) to be inserted into the body, and the proximal end side of the catheter1is the side (proximal side) to be operated by a technician such as a doctor. The catheter1is used for diagnosing or treating a constricted part or an obstruction part. For example, the catheter1is inserted into a blood vessel of a heart in which a constricted part is formed and then used to expand the intravascular constricted part.

As shown inFIG.1, the catheter1includes the multi-lumen tube10, the distal tip15, a balloon16, and a connector17, and is configured here as a balloon catheter. As shown inFIGS.1and2, the multi-lumen tube10is a long member having two lumens inside, and has an outer layer20, a first inner layer tube30, a reinforcing body40, and a second inner layer tube50. The distal tip15is provided at the distal end of the catheter1and has an opening (not shown) that communicates with the first inner layer tube30. The balloon16is provided between the multi-lumen tube10and the distal tip15, and the internal space of the balloon16communicates with the second inner layer tube50. The connector17is connected to the proximal end of the multi-lumen tube10and has an opening (not shown) that communicates with the first inner layer tube30and the second inner layer tube50. As an example, the catheter1can be used to take out a guide wire or another catheter inserted through the opening of the connector17from the opening of the distal tip15via the inside of the first inner layer tube30. Further, the catheter1can be used to supply a fluid from the opening of the connector17to the internal space of the balloon16via the second inner layer tube50.

The first inner layer tube30is a tube formed of a resin, wherein a lumen into which a guide wire or another catheter is inserted is formed inside. Resin materials for forming the first inner layer tube30are not particularly limited. Examples thereof can include PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PFA (perfluoroalkoxy alkane), FEP (perfluoroethylene propene), ETFE (ethylene tetrafluoroethylene), PE (polyethylene), and PP (polypropylene). The outer diameter of the first inner layer tube30is configured to be larger than the outer diameter of the second inner layer tube50.

The reinforcing body40is a braided body (metal blade layer) in which the first wire and the second wire are woven into each other in a mesh shape, is disposed on the outer periphery of the first inner layer tube30, and is covered (buried) by an outer layer20. The reinforcing body40may cover the entire first inner layer tube30, or may cover a part of the first inner layer tube30.

The second inner layer tube50is a tube formed of a resin, and a lumen for flowing a fluid is formed inside. The resin material forming the second inner layer tube50is not particularly limited. The second inner layer tube50may be formed of the same type of resin as that of the first inner layer tube30or a type of resin different from that of the first inner layer tube30. The outer diameter of the second inner layer tube50is configured to be smaller than the outer diameter of the first inner layer tube30.

The outer layer20is formed of a resin and covers the first inner layer tube30, the reinforcing body40, and the second inner layer tube50. The outer layer20is formed by placing seven types of resins having different properties from each other in the axial (longitudinal) direction and joining resins adjacent to each other, thereby having 7 regions (N0to N6) formed of different resins. The resin material forming each region of the outer layer20is not particularly limited, and examples thereof can include polyamide, polyamide elastomer, polyester, polyurethane, and polyurethane elastomer. Further, the resins forming the outer layer20may contain tungsten powder, and the hardness of the resins may be changed depending on the contents thereof. The resins forming the outer layer20can contain tungsten powder that is a radiation-impermeable powder, so that a technician such as a doctor can accurately grasp the position of the catheter1at the time of coronary angiography.

Here, in the outer layer20, regions formed of resins having different properties from each other are also referred to as, in order from the distal end side to the proximal end side of the outer layer20, the distal end region N0, the first region N1, the second region N2, the third region N3, the fourth region N4, the fifth region N5, and the sixth region N6. The distal end side of the distal end region N0of the outer layer20is connected to the proximal end side of the balloon16, and the proximal end side of the distal end region N0is connected to the distal end side of the first region N1. The distal end side of the second region N2of the outer layer20is connected to the proximal end side of the first region N1, and the proximal end side of the second region N2is connected to the distal end side of the third region N3. In the outer layer20, the distal end side of the fourth region N4is connected to the proximal end side of the third region N3, and the proximal end side of the fourth region N4is connected to the distal end side of the fifth region N5. In the outer layer20, the distal end side of the sixth region N6is connected to the proximal end side of the fifth region N5, and the proximal end side of the sixth region N6is connected to the connector17.

The outer layer20is configured so that the hardness H0of a resin21forming the distal end region N0, the hardness H1of a resin22forming the first region N1, the hardness H2of a resin23forming the second region N2, the hardness H3of a resin24forming the third region N3, the hardness H4of a resin25forming the fourth region N4, the hardness H5of a resin26forming the fifth region N5, and the hardness H6of a resin27forming the sixth region N6satisfy the following formula (1).
H0<H1<H2<H3<H4<H5<H6  (1)

That is, the catheter1is configured so that the hardness of the resins of the outer layer20increases from the distal end side to the proximal end side. This makes it possible to improve the passage of the catheter1through a tubular organ such as a blood vessel.

In general, it is preferable that the flexural rigidity of a catheter gradually increases from the distal end portion to the proximal end portion. The distal end portion has relatively high flexibility, making it possible to hardly damage the inner surface of the blood vessel even in a vessel bifurcation at a steep angle. On the other hand, the proximal end portion has relatively high rigidity, making it possible to enhance the torque transmissibility for transmitting the rotational movement of the catheter by the operator to the distal end portion side. Further, making the change in the rigidity of a catheter in the axial direction at a level as constant as possible can suppress the occurrence of kinking etc., due to the rigidity gap. Therefore, the catheter having flexural rigidity gradually increasing from the distal end portion to the proximal end portion can improve the passage of the catheter1through a tubular organ such as a blood vessel.

In the present embodiment, the “hardness of the resin” is not limited to the hardness of the resin itself, but means the entire hardness including the hardness of the resin itself plus the hardness of the material to be kneaded with the resin. Therefore, a method for varying the hardness of resins is not limited to varying the resin types. The hardness of resins can also be varied by varying the amount of the material to be kneaded with the same type of resin.

The configuration in the vicinity of the joint part between the first region N1and the second region N2of the outer layer20will be described with reference toFIGS.3to6.FIG.3is an explanatory view of the X portion inFIG.1of the multi-lumen tube10as viewed from the D1direction inFIG.2.FIG.4is an explanatory view of the X portion inFIG.1of the multi-lumen tube10as viewed from the D2direction ofFIG.2. InFIG.2, when the outer surface of the outer layer20is divided into an upper side (second inner layer tube50side) and a lower side (first inner layer tube30side),FIG.3shows a half on the upper side of the outer surface of the outer layer20.FIG.4shows a half on the lower side of the outer surface of the outer layer20. In other words, when the outer layer20is divided into a side where the first inner layer tube30is located and a side where the second inner layer tube50is located along the circumferential direction of the outer layer20,FIG.3shows the side where the second inner layer tube50is located (the second inner layer tube50side of the outer layer20), andFIG.4shows the side where the first inner layer tube30is located (the first inner layer tube30side of the outer layer20).

As shown inFIG.3, on the second inner layer tube50side of the outer layer20, the resin22of the first region N1enters the second region N2in the joint part C1between the first region N1and the second region N2, so as to form a wave pattern. A portion of the resin22having entered the second region N2is also referred to as an entering resin221. The entering resin221is provided on both sides of the second inner layer tube50in the circumferential direction of the outer layer20. In other words, in the outer layer20, the resin22of the first region N1has entered the second region N2on both sides of the second inner layer tube50in the circumferential direction of the outer layer20, so that a wave pattern is formed by the resin22having entered on both sides of the second inner layer tube50. The wave pattern may be formed by: the alternate repetition of a portion with the entering resin221and a portion without the entering resin221; or varied distances the entering resin221has entered in the circumferential direction of the outer layer20(a change of the end edge position the entering resin221).

As shown inFIG.4, on the first inner layer tube30side of the outer layer20, the resin22of the first region N1has not substantially entered the second region N2in the joint part C1between the first region N1and the second region N2, so as to form no wave pattern. Therefore, the boundary between the first region N1and the second region N2is substantially linear along the circumferential direction of the outer layer20. In addition, also on the first inner layer tube30side of the outer layer20, a wave pattern may be formed by the resin22of the first region N1having entered the second region N2in the joint part C1between the first region N1and the second region N2, similarly to the second inner layer tube50side (FIG.3) of the outer layer20.

FIG.5is an explanatory view illustrating a cross section taken along the line B-B ofFIG.3in the multi-lumen tube10.FIG.6is an explanatory view illustrating a cross section taken along the line C-C ofFIG.3in the multi-lumen tube10. As shown inFIG.5, the entering resin221having entered the second region N2is located on both sides of the second inner layer tube50and is in contact with the reinforcing body40and the first inner layer tube30. Further, the entering resin221is covered by the resin23. On the outer surface of the outer layer20, the entering resin221can be visually recognized through the resin23. As shown inFIG.6, the entering resin221having entered the second region N2of the outer layer20is formed by flowing of the resin22of the first region N1into the second region N2side at the time of producing the multi-lumen tube10described later. Therefore, the entering resin221becomes thinner (toward the proximal end direction) as the distance from the first region N1to the second region N2increases.

A method for producing the multi-lumen tube10will be described with reference toFIGS.7A to9.FIGS.7A-7Fillustrate the production steps of the multi-lumen tube10. In producing the multi-lumen tube10, first, as shown inFIG.7A, the first inner layer tube30in which the reinforcing body40is disposed on the outer periphery and the second inner layer tube50are prepared. Next, as shown inFIG.7B, outer layer tubes200are disposed outside the prepared first inner layer tube30and the second inner layer tube50. The outer layer tubes200are tubular members formed of resins that are raw materials of the outer layer20, and are prepared for each type of resin of the outer layer20. Here, an outer layer tube (not shown) formed of the resin21of the distal end region N0, an outer layer tube202formed of the resin22of the first region N1, an outer layer tube203formed of the resin23of the second region N2, an outer layer tube204formed of the resin24of the third region N3, an outer layer tube (not shown) formed of the resin25of the fourth region N4, an outer layer tube (not shown) formed of the resin26of the fifth region N5, and an outer layer tube (not shown) formed of the resin27of the sixth region N6are prepared. The first inner layer tube30and the second inner layer tube50are sequentially inserted into the prepared seven outer layer tubes200to prepare an assembly100shown inFIG.7C.

FIG.8is an explanatory view illustrating a transverse section of the assembly100. The inner diameter of the outer layer tubes200is larger than the sum of the two outer diameters of the first inner layer tube30and the second inner layer tube50, producing a gap between the outer peripheries of the first inner layer tube30and the second inner layer tube50housed in the outer layer tubes200and the inner periphery of the outer layer tubes200in the assembly100. In particular, the outer diameter of the second inner layer tube50is smaller than the outer diameter of the first inner layer tube30, producing relatively a large gap Sp on both sides of the second inner layer tube50.

Returning to the discussion of the production method, after preparing the assembly100ofFIG.7C, the outer layer tubes200are heated from the outside as shown inFIGS.7D and7Eto melt the resins constituting the outer layer tubes200and thus to form the outer layer20. That is, the outer layer tubes200are heated to pour the molten resin between the outer peripheries of the first inner layer tube30and the second inner layer tube50and the inner periphery of the outer layer tubes200and thus to fill the gap. Here, the seven outer layer tubes200are heated one by one in order, instead of heating all the tubes200simultaneously. As for the order of heating, in the present embodiment, heating is performed in order from the distal end side to the proximal end side. That is, here, the outer layer tube of the distal end region N0(not shown), the outer layer tube202of the first region N1, the outer layer tube203of the second region N2, the outer layer tube204of the third region N3, the outer layer tube (not shown) of the fourth region N4, the outer layer tube (not shown) of the fifth region N5, and the outer layer tube (now shown) of the sixth region N6are heated in this order.FIG.7Dshows a state in which the outer layer tube202is heated to melt the resin.FIG.7Eshows a state in which the outer layer tube203is heated to melt the resin.

FIG.9is an explanatory view illustrating a vertical cross section of the assembly100when the outer layer tube202is melted. When the outer layer tube202is heated to melt the resin, a part of the molten resin flows into the inside of the outer layer tube203adjacent on the proximal end side. As a result, the entering resin221is formed. In particular, relatively a large gap Sp (seeFIG.8) is formed on both sides of the second inner layer tube50inside the outer layer tube203, so that the resin flows into the gap Sp and the relatively large entering resin221is formed.

Returning to the discussion of the production method, the outer layer tube202is melted to form the first region N1of the outer layer20, and then the outer layer tube203is heated to melt the resin as shown inFIG.7E. At this time, a part of the molten resin flows into the inside of the outer layer tube204adjacent on the proximal end. As a result, the second region N2of the outer layer20is formed, and the entering resin231is formed. In this way, the seven outer layer tubes200are heated from the outer layer tube on the distal end side, so that as shown inFIG.7F, the production of the multi-lumen tube10is completed in which the resin of the distal end side region has entered the adjacent proximal end side region. The outer layer20of the multi-lumen tube10includes a joint part between the distal end region N0and the first region N1, a joint part between the second region N2and the third region N3, a joint part between the third region N3and the fourth region N4, a joint part between the fourth region N4and the fifth region N5, and a joint part between the fifth region N5and the sixth region N6, wherein the configuration of each joint part is the same as that of the joint part C1between the first region N1and the second region N2shown inFIGS.3and4.

Examples of the Effects of this Embodiment

According to the multi-lumen tube10of the present embodiment described above, the entering resin221(FIG.3) forms a wave pattern in the joint part C1between the first region N1and the second region N2of the outer layer20, so that the joint area can be increased as compared with a case where the joint part is linear. Accordingly, the joint strength at the joint part C1between the first region N1and the second region N2can be improved. Further, the entering resin221is formed to realize the gradual switching from the resin22constituting the first region N1to the resin23constituting the second region N2in the joint part C1, so that the change in flexural rigidity due to the difference in the type of resin forming the outer layer20can be made gradual. As a result, the rigidity gap of the flexural rigidity in the vicinity of the joint part C1is less likely to occur, so that the occurrence of kinking and breakage due to stress concentration can be suppressed.

Further, according to the multi-lumen tube10of the present embodiment, a wave pattern is formed on the second inner layer tube50side of the outer layer20in the joint part C1(FIG.3) between the first region N1and the second region N2. Therefore, the change in the flexural rigidity of the outer layer20can be made gradual around the second inner layer tube50. As a result, a rigidity gap is less likely to occur around the second inner layer tube50, so that the crush resistance of the second inner layer tube50can be further improved. Further, as shown inFIG.7D, the position of the second inner layer tube50inside the outer layer tube203is fixed by the entering resin221. Therefore, as shown inFIG.7E, when the outer layer20is formed by heating the outer layer tube203, it is possible to prevent the second inner layer tube50from being pushed and displaced by the molten resin.

In particular, according to the multi-lumen tube10of the present embodiment, as shown inFIG.3, the resin22(entering resin221) has entered on both sides of the second inner layer tube50in the joint part C1between the first region N1and the second region N2, so as to form a wave pattern. As a result, the movement of the second inner layer tube50is restricted by the entering resin221on both sides of the second inner layer tube50, so that the displacement of the second inner layer tube50can be further suppressed when the outer layer20is formed.

Further, according to the multi-lumen tube10of the present embodiment, the entering resin231also forms a wave pattern in the second joint part between the second region N2and the third region N3of the outer layer20, so that the joint area of the second joint part can be increased and the joint strength can be improved. Further, the entering resin231is formed to realize the gradual switching from the resin23constituting the second region N2to the resin24constituting the third region N3in the second joint part, so that it is possible to make it difficult for a rigidity gap to occur in the vicinity of the second joint part.

Further, in the catheter1of the present embodiment, the hardness H1of the resin22of the first region N1is lower than the hardness H2of the resin23of the second region N2. According to this configuration, the rigidity can be gradually increased from the distal end to the proximal end of the catheter1, so that the passage of the catheter1through a tubular organ such as a blood vessel can be improved. As described, the passage of the catheter1through a tubular organ such as a blood vessel can be improved by gradually increasing the flexural rigidity from the distal end portion to the proximal end portion thereof. In the catheter1of the present embodiment, the hardness H1of the resin22of the first region N1is lower than the hardness112of the resin23of the second region N2, so that the position where the flexural rigidity changes can be multi-staged in the axial direction of the catheter1. As a result, the rigidity can be gradually increased from the distal end to the proximal end of the catheter1, so that the passage of the catheter1through a tubular organ such as a blood vessel can be improved while suppressing the occurrence of a rigidity gap.

Second Embodiment

FIG.10is an explanatory view illustrating the vicinity of the joint part C1of a multi-lumen tube10A of the second embodiment.FIG.10corresponds toFIG.4for the first embodiment. In the multi-lumen tube10of the first embodiment, as shown inFIG.4, on the first inner layer tube30side of the outer layer20, the resin22of the first region N1has not substantially entered the second region N2in the joint part C1, forming no wave pattern. However, as in the multi-lumen tube10A of the second embodiment shown inFIG.10, the resin22of the first region N1may enter the second region N2to form a wave pattern in the joint part C1on the first inner layer tube30side of the outer layer20, as in the case of the second inner layer tube50side of the outer layer20.

In this case, the joint area between the resin22of the first region N1and the resin23of the second region N2of the outer layer20can be further increased. Further, the entering resin221is disposed in a more balanced manner in the circumferential direction of the outer layer20, so that the joint strength at the joint part C1between the first region N1and the second region N2can be further improved. As described above, according to the multi-lumen tube10A of the present embodiment, on the first inner layer tube30side of the outer layer20, the resin22of the first region N1may or may not enter the second region N2in the joint part C1. However, the resin preferably enters also on the first inner layer tube30side.

Third Embodiment

FIG.11is an explanatory view illustrating the vicinity of the joint part C1of the multi-lumen tube10B of the third embodiment.FIG.11corresponds toFIG.3for the first embodiment. In the multi-lumen tube10of the first embodiment, as shown inFIG.3, on the second inner layer tube50side of the outer layer20, the resin22of the first region N1enters the second region N2on both sides of the second inner layer tube50to form a wave pattern. However, as in the multi-lumen tube10B of the third embodiment shown inFIG.11, on the second inner layer tube50side of the outer layer20, the resin22of the first region N1may enter the second region N2on only one side of the second inner layer tube50. Even in this case, since a wave pattern is formed by the portion where the resin22has entered the second region N2(entering resin221) and the portion where the resin22has not entered, the joint area can be more increased as compared with a case where the joint part C1is linear. Accordingly, the joint strength at the joint part C1between the first region N1and the second region N2can be improved.

As described above, according to the multi-lumen tube10B of the present embodiment, on the first inner layer tube30side of the outer layer20, the resin22may enter the second region N2on both sides of the second inner layer tube50, or the resin22may enter the second region N2only on one side of the second inner layer tube50. However, it is preferable that the resin22of the first region N1enters the second region N2to form a wave pattern on both sides of the second inner layer tube50. On the outer peripheral surface of the outer layer20, the resin22may enter the second region N2only in the portion where the second inner layer tube50is located, or may enter the second region N2in the portion where the second inner layer tube50is located and on both sides thereof.

Fourth Embodiment

FIGS.12A-12Fillustrate the production steps of a multi-lumen tube10C of the fourth embodiment.FIGS.12A-12Fcorrespond toFIGS.7A-7Ffor the first embodiment. The steps shown inFIGS.12A to12Care the same as the steps shown inFIGS.7A to7C. In the production steps of the multi-lumen tube10of the first embodiment, as shown inFIGS.7D and7E, the seven outer layer tubes200are heated in order from the outer layer tube on the distal end side. However, in the production steps of the multi-lumen tube10C of the fourth embodiment shown inFIGS.12A-12F, the seven outer layer tubes200are heated in order from the proximal end side to the distal end side. Specifically, here, the outer layer tube in the sixth region N6(not shown), the outer layer tube in the fifth region N5(not shown), the outer layer tube in the fourth region N4(not shown), the outer layer tube204in the third region N3, the outer layer tube203in the second region N2, the outer layer tube202in the first region N1, and the outer layer tube in the distal end region N0(not shown) are heated in this order.

FIG.12Dshows a state in which the outer layer tube204is heated to melt the resin. When the outer layer tube204is heated to melt the resin, a part of the molten resin flows into the inside of the outer layer tube203adjacent on the distal end side. As a result, the entering resin242is formed. In particular, since a relatively large gap Sp (seeFIG.8) is formed on both sides of the second inner layer tube50inside the outer layer tube203, the resin flows into the gap Sp to form the relatively large entering resin242.

After the outer layer tube204is melted to form the third region of the outer layer20, the outer layer tube203is heated to melt the resin as shown inFIG.12E. At this time, a part of the molten resin flows into the inside of the outer layer tube202adjacent on the distal end side. As a result, the entering resin232is similarly formed. In this way, the seven outer layer tubes200are heated in order from the outer layer tube on the proximal end side, so as to complete the production of the multi-lumen tube10C as shown inFIG.12F, wherein the resin of each proximal end side region has entered the adjacent distal end side region.

As described above, according to the multi-lumen tube10C of the present embodiment, as for the resin of each region constituting the outer layer20, the resin constituting each region on the proximal end side may enter the region on the distal end side. Even in this case, the entering resin having entered from the proximal end side to the distal end side forms a wave pattern in the joint part between the two regions adjacent to each other of the outer layer20, so that the joint area can be increased more than that in the case of the linear joint part. Accordingly, the joint strength at the joint part between the two adjacent regions can be improved. Further, in the joint part between the two adjacent regions, the change in flexural rigidity due to the difference in the type of resin can be made gradual. As a result, a rigidity gap of flexural rigidity in the vicinity of the joint part is less likely to occur, so that the occurrence of kinking and fracture due to stress concentration can be suppressed.

Fifth Embodiment

FIGS.13A-13Fillustrate the production steps of a multi-lumen tube10D of the fifth embodiment.FIGS.13A-13Fcorrespond toFIGS.7A-7Ffor the first embodiment. The steps shown inFIGS.13A to13Care the same as the steps shown inFIGS.7A to7C. In the production steps of the multi-lumen tube10of the first embodiment, the seven outer layer tubes200are heated in order from the outer layer tube on the distal end side. However, the order for heating the seven outer layer tubes200is not limited to the order from one end toward the other end of the assembly100. The order for heating the seven outer layer tubes200can be arbitrarily set. Further, a plurality of the seven outer layer tubes200may be heated simultaneously as long as they are not adjacent to each other.

As shown inFIG.13D, in the production steps of the multi-lumen tube10D of the fifth embodiment, the outer layer tube202of the first region N1and the outer layer tube204of the third region N3are simultaneously heated, and then the outer layer tube203of the second region N2is heated as shown inFIG.13E. Next, although not shown, the outer layer tube of the distal end region N0and the outer layer tube of the fifth region N5are heated in order, and then the outer layer tube of the fourth region N4and the outer layer tube of the sixth region N6are heated simultaneously.

As shown inFIG.13D, when the outer layer tube202is heated to melt the resin, a part of the molten resin flows into the inside of the outer layer tube203adjacent on the rear end side. As a result, the entering resin221is formed. Further, when the outer layer tube204is heated to melt the resin, a part of the molten resin flows into the inside of the outer layer tube203adjacent on the distal end side. As a result, the entering resin242is formed. After melting the outer layer tube202and the outer layer tube204, the outer layer tube203is heated to melt the resin as shown inFIG.13E. In this way, the outer layer tubes202and204on both sides of the outer layer tube203are heated before heating the outer layer tube203, so that the production of the multi-lumen tube10D is completed, wherein each resin from the first region N1and the third region N3has entered the second region N2, as shown inFIG.13F.

As described above, according to the multi-lumen tube10D of the present embodiment, the resin of each region constituting the outer layer20may enter the adjacent region on the distal end side or enter the adjacent region on the proximal end side. Even in these cases, in two regions adjacent to each other, the entering resin enters from one of the regions into the other region, so as to form a wave pattern in the joint part. As a result, the joint area can be increased and the joint strength at the joint part can be improved as compared with the case where the joint part is linear.

Sixth Embodiment

FIG.14is an explanatory view illustrating the appearance of the catheter1E including a multi-lumen tube10E of the sixth embodiment.FIG.14corresponds toFIG.1for the first embodiment. The outer layer20of the multi-lumen tube10of the first embodiment has seven regions N0to N6formed of resins having different properties from each other. However, the number of regions of the outer layer20of the multi-lumen tube10is not limited to 7, and can be any number of 2 or more. Further, in the first embodiment, an example in which the multi-lumen tube10is applied to a balloon catheter is shown, but the multi-lumen tube10is also applicable to a catheter other than the balloon catheter.

The sixth embodiment shown inFIG.14shows an example in which the multi-lumen tube10E is applied to a catheter including no balloon. Further, the multi-lumen tube10E of the present embodiment includes two regions formed of different resins in the outer layer20. Here, the two regions are referred to as a first region N1and a second region N2in this order from the distal end side to the proximal end side of the outer layer20. The distal end side of the first region N1of the outer layer20is connected to the distal tip15, and the proximal end side of the first region N1is connected to the distal end side of the second region N2. The proximal end side of the second region N2of the outer layer20is connected to the connector17.

The outer layer20is configured such that the hardness H1of the resin22forming the first region N1and the hardness H2of the resin23forming the second region N2satisfy the following formula (2).
H1<H2  (2)

That is, the catheter1is configured so that the hardness of the resins of the outer layer20increases from the distal end side to the proximal end side. This makes it possible to improve the passage of the catheter1through a tubular organ such as a blood vessel. Similar to the first embodiment, in the joint part C1between the first region N1and the second region N2of the outer layer20, a wave pattern is formed by the resin22of the first region N1having entered the second region N2. The configuration of the joint part C1between the first region N1and the second region N2of the outer layer20is the same as that shown inFIGS.3and4for the first embodiment.

As described above, according to the multi-lumen tube10E of the present embodiment, the number of types of resins constituting the outer layer20, that is, the number of regions of the outer layer20, can be any number of 2 or more. In any case, in two regions adjacent to each other, the entering resin enters from one of the regions to the other region, so as to form a wave pattern in the joint part. As a result, the joint area can be increased and the joint strength at the joint part can be improved as compared with the case where the joint part is linear.

FIG.15is an explanatory view illustrating a transverse section of a multi-lumen tube10F of the seventh embodiment.FIG.15corresponds toFIG.2for the first embodiment. In the multi-lumen tube10of the first embodiment, as shown inFIG.2, the reinforcing body40is disposed on the outside of the first inner layer tube30. However, like the multi-lumen tube10F of the seventh embodiment shown inFIG.15, the reinforcing body need not be disposed on the outside of the first inner layer tube30. Even in this case, as in the case of the outer layer20of the first embodiment, if a wave pattern is formed in the joint part C1between the first region N1and the second region N2, the joint area can be increased as compared with a case where the joint part C1is linear. Accordingly, the joint strength at the joint part C1between the first region N1and the second region N2can be improved.

FIG.16is an explanatory view illustrating a transverse section of a multi-lumen tube10G of the eighth embodiment.FIG.16corresponds toFIG.2for the first embodiment. In the multi-lumen tube10of the first embodiment, as shown inFIG.2, the outer diameter of the second inner layer tube50is smaller than the outer diameter of the first inner layer tube30. However, as in the multi-lumen tube10G of the eighth embodiment shown inFIG.16, the outer diameter of a second inner layer tube51may be equal to the outer diameter of a first inner layer tube31. Even in this case, when the multi-lumen tube10G is produced, a gap is formed between the second inner layer tube51and the first inner layer tube31and the outer layer tube200(seeFIG.8). Hence, the molten resin of the outer layer tube can be poured into the gap, so as to form an entering resin. As a result, similar to the outer layer20of the first embodiment, a wave pattern is formed in the joint part C1between the first region N1and the second region N2to increase the joint area, and thus the joint strength at the joint part C1can be improved. As shown inFIG.16, reinforcing bodies41and42may be disposed on the outer peripheries of the first inner layer tube31and the second inner layer tube51, respectively, or one reinforcing body may not be disposed on at least one of the outer peripheries of the first inner layer tube31and the second inner layer tube51.

FIG.17is an explanatory view illustrating a transverse section of a multi-lumen tube10H of the ninth embodiment.FIG.17corresponds toFIG.2for the first embodiment. As shown inFIG.2, the multi-lumen tube10of the first embodiment includes two inner layer tubes (the first inner layer tube30and the second inner layer tube50). However, the number of inner layer tubes included in the multi-lumen tube10is not limited to 2, and can be any number. For example, as in the multi-lumen tube10H of the ninth embodiment shown inFIG.17, three inner layer tubes, a first inner layer tube32, a second inner layer tube52, and a third inner layer tube60, may be included. Even in this case, at the time of production of the multi-lumen tube10H, a gap is formed between the three inner layer tubes32,52,60and the outer layer tubes200(seeFIG.8). Hence, the molten resins of the outer layer tubes200can be poured into the gap, so as to form entering resins. As a result, similar to the outer layer20of the first embodiment, a wave pattern is formed in the joint part C1between the first region N1and the second region N2to increase the joint area, so that the joint strength at the joint part C1can be improved.

Modification Example of the Embodiments

The disclosed embodiments are not limited to the above-described embodiments, and can be implemented in various aspects without departing from the gist thereof. For example, the following modification examples are also possible.

Modification Example 1

In the first and fourth embodiments (FIGS.7A-7F and12A-12F), the outer layer tubes200are heated one by one in the production steps of the multi-lumen tubes10and10C, and in the fifth embodiment (FIGS.13A-13F), two outer layer tubes200are heated simultaneously. However, in the production steps, three or more outer layer tubes200may be heated simultaneously. Even in this case, a wave pattern can be formed in the joint part C1between the first region N1and the second region N2by the entering resin, and the joint area can be increased. Note that it is preferable to simultaneously heat a plurality of outer layer tubes200that are not adjacent to each other rather than the outer layer tubes200that are adjacent to each other because this facilitates the formation of an entering resin.

Modification Example 2

In the above embodiment, the number of inner layer tubes (number of lumens) included in the multi-lumen tube ranges from 2 to 3. However, the number of inner layer tubes included in the multi-lumen tube is not limited to 2 to 3. The multi-lumen tube may include four or more inner layer tubes. The present embodiment is also applicable to a single lumen tube having one lumen. Even in this case, a wave pattern can be formed in the joint part C1between the first region N1and the second region N2by the entering resin, and the joint area can be increased.

Modification Example 3

The number of types of resins constituting the outer layer20, that is, the number of regions of the outer layer20may be 8 or more. Further, when the outer layer20has a plurality of regions, the hardness of the resin constituting the region on the distal end side of the catheter1may be higher than the hardness of the resin constituting the region on the proximal end side. Further, the entering resin may not be covered by the resin on the side the other resin has entered, and may be exposed. Further, the outer diameter of the multi-lumen tube may be constant or may be varied in the axial direction.

Modification Example 4

In the multi-lumen tube of the above-described embodiment, a visible wave pattern is formed in the joint part C1of the outer layer20. However, the wave pattern formed in the joint part C1may not always be visible. Even in this case, if the joint area can be increased by the entering resin, the joint strength can be improved. Further, the shape of the pattern formed in the joint part C1by the entering resin may not always be a wave pattern. For example, it may have a chevron shape or a rectangular shape. Even in these cases, the joint strength can be improved by the entering resin.

Modification Example 5

The multi-lumen tube of the above-described embodiment includes no coil body on the outside of the inner layer tubes. However, the multi-lumen tube may include a coil body on the outside of the inner layer tubes. Further, the outer diameters of the inner layer tubes may be constant or may be varied in the axial direction.

Modification Example 6

In the outer layer20of the present embodiment, regions are formed of different types of resins. However, the regions may be of the same type of resin and may be configured such that the amounts of the materials to be kneaded into the resin are different from each other. Even in this case, since the hardness of the resin can be varied, the rigidity can be gradually increased from the distal end side to the proximal end side of the multi-lumen tube10. At least two or more regions among the regions of the outer layer20may be formed of the same type of resin and have the same hardness. For example, two adjacent regions may be formed of the same type of resin. Even in this case, since the joint area is increased by the entering resin, the joint strength can be increased. Further, when the resin melted by heating one of the outer layer tubes200is poured around an inner layer tube, it is possible to prevent the inner layer tube from being displaced by the molten resin. When the two adjacent regions of the outer layer20are formed of different types of resins, the change in rigidity in the joint part C1can be made gradual.

Modification Example 7

In the outer layer20of the present embodiment, the order of heating matches the order of melting the resin of each region of the outer layer20. However, the resin of the adjacent region may be melted first despite of the order of heating, and thus this resin of the adjacent region may flow into the region where the heating is started previously to form a wave pattern. For example, when heating is started from the proximal end side of the catheter1, the resin having lower hardness in the adjacent region on the distal end side melts earlier than the resin having higher hardness on the proximal end side, and flows into the proximal end side region, and thus a wave pattern may be formed. Even in that case, the change in rigidity in the joint part C1can be made gentle as a result of flowing of the resin with low hardness into the region of the resin with high hardness.

Modification Example 8

The catheter1of the present embodiment may have or may not have a resin coating formed outside the outer layer20. When a resin coating is formed outside the outer layer20, different types of resin films may be formed, or the same type of resin films may be formed in at least a part of each region of the outer layer.

Modification Example 9

The configuration of this embodiment is also applicable to medical devices other than balloon catheters. For example, the configuration of the present embodiment is also applicable to a multi-lumen catheter, a single-lumen catheter, a dilator, an endoscope, a guide wire, and the like without a balloon. In addition, parts of each configuration of the multi-lumen tube illustrated in the first to ninth embodiments can be appropriately combined and can be appropriately removed.

Although the aspects have been described above based on the embodiments and modification examples, the embodiments of the above-described aspects are described herein to facilitate the understanding of the present aspects, and do not limit the present aspects. These aspects may be modified or improved without departing from their spirit and claims, and these aspects include their equivalents. In addition, if the technical features are not described as essential in the present specification, they may be deleted as appropriate.

DESCRIPTION OF REFERENCE NUMERALS