JP2000279507A - Balloon catheter with low-temperature blow-molded balloon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the breaking strength of a balloon by forming the balloon part out of a cross-linking tube composed of crystallizable polyolefinic resin by blow molding and executing the blow molding of the cross-linking tube under a specific temperature condition. SOLUTION: This expansion balloon catheter 2 has a balloon part 4, an outer tube 6, and a connector 8. The balloon part 4 has its both ends formed of diameter-reduced cylindrical film bodies, the proximal end of the balloon part 4 is joined with the distal end outer circumference of the outer tube member 6a by a means such as thermal fusion or adhesion, and a lumen 10 of the outer tube member 6a is communicated with the inner expansion space of the balloon part 4. The balloon part 4 is formed using a cross-linking tube composed of crystallizable polyolefinic resin by a blow molding and in the case, the blow molding is executed at a temperature lower than the melting point of the crystallizable polyolefinic resin by 10 deg.C or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balloon catheter having an expansion balloon having relatively high strength, and more particularly to a balloon catheter having an expansion balloon having excellent blow moldability.

[0002]

2. Description of the Related Art Percutaneous intravascular coronary angioplasty (Percutaneous T) which can be easily treated and recovered by a balloon catheter for diseases caused by stenosis of blood vessels.
ransluminal Coronary Angi
oplasty) catheters (hereinafter referred to as "PTCA catheters") are frequently used.

The above PTCA catheters include an over-the-wire balloon catheter and a monorail balloon catheter. The over-the-wire balloon catheter has a guide wire lumen formed over the entire length of the catheter tube,
A guide wire is inserted through the lumen, and the balloon is guided to the stenosis along the guide wire.

On the other hand, in a monorail type balloon catheter, an opening is formed in the middle of the catheter tube, and the opening is guided to a distal end of the balloon through a guide wire insertion lumen. Therefore, in this type of balloon catheter, the length of the guide wire extending outside the body for replacement of the balloon catheter may be slightly longer than the length corresponding to the length from the opening to the distal end of the balloon. , Compared to the over-the-wire system.

In a PTCA catheter, for example, in the treatment of the coronary artery of the heart, a guiding catheter is first inserted to the entrance of the coronary artery, a guide wire is inserted beyond the stenosis, and the balloon catheter is inserted into the stenosis. To expand the stenosis by expanding the balloon.

In this case, the balloon is required to be able to safely dilate the blood vessel, and is required to have a large breaking strength so that it can withstand a strong expansion pressure.

[0007] Conventionally, as a material of the balloon,
Crystalline polyethylene resins are mainly used because they have a relatively good balance between processability and physical properties. In general, the balloon is, for example, to make a crosslinked tube by performing electron beam treatment on a crystalline polyethylene resin tube, in order to ensure a sufficient stretching magnification of the balloon,
For example, when the melting point of polyethylene is about 115 ° C., it is made by blow molding the crosslinked tube at about 110 ° C., which is slightly lower than this.
In that case, the total draw ratio from the cross-linked tube to the balloon is said to reach 5 times or more (for example, JP-A-8-196620).

[0008] However, as the required level of the characteristics of the balloon catheter has become higher, there has been a problem that a conventional balloon molded from a crystalline polyethylene resin cannot ensure a sufficient breaking strength, and a solution has been desired. .

[0009]

An object of the present invention is to provide a balloon catheter having a relatively high-strength balloon, and more particularly, to provide a balloon catheter suitable for PTCA use having a balloon having excellent blow moldability. With the goal. Still another object of the present invention is to provide a method for forming a polyolefin-based resin balloon having high breaking strength and a method for manufacturing a balloon catheter having such a balloon.

Therefore, the present inventors have conducted intensive research and have found that
A polyethylene-made crosslinked tube made by irradiating a crystalline polyethylene resin with an electron beam is set at 40 ° C. below its melting point.
When blow molding was carried out under the condition of 75 to 80 ° C. which is about low temperature, it was found that the breaking strength of the obtained balloon was increased as compared with the balloon obtained by blow molding near the melting point (113 ° C.). The present invention has been completed based on the findings.

[0011]

According to the present invention, the following (1) and (2) are provided. (1) an outer tube in which at least one balloon inflation lumen is formed along the longitudinal direction; and a balloon end in which a proximal end of a balloon portion is joined to a distal end of the outer tube. The balloon communicates with the inside thereof, and the distal end of the balloon is joined to the distal end of the inner tube so as to form a sealed expansion space inside the balloon. And a balloon catheter having an inner tube extending in the axial direction inside the balloon expansion lumen of the outer tube, wherein the balloon portion is blow-molded using a cross-linked tube made of a crystalline polyolefin resin. The blow molding is performed at a temperature lower than the melting point of the crystalline polyolefin resin by 10 ° C. or more. Balloon catheter according to claim. (2) a step of preparing a cross-linked tube by electron beam cross-linking a tube made of a crystalline polyolefin-based resin, and applying a primary blow pressure to the cross-linked tube at a temperature lower than the melting point of the crystalline polyolefin-based resin by 10 ° C. or more. And then applying a secondary blow pressure, which is lower than the primary blow pressure, to the cross-linking tube to prepare a balloon portion, and at least one balloon expansion lumen extends in the longitudinal direction. Bonding the proximal end of the balloon portion to the distal end of the outer tube formed in such a manner that the balloon expansion lumen and the inside of the balloon portion communicate with each other. And an inner tube extending axially inside the balloon portion and inside the balloon expansion lumen of the outer tube, and a distal end of the inner tube. , So as to form an extended space which is sealed to the inside of the balloon portion, the manufacturing method of a balloon catheter and a step of bonding the distal end of the balloon portion.

The balloon catheter of the present invention can employ either an over-the-wire system or a monorail system. For the over-the-wire method,
An inner tube extending axially into the interior of the balloon portion and the interior of the balloon inflation lumen of the outer tube member has a proximal end opening through the proximal end of the outer tube and the connector. Open to the outside.

[0013] In the case of the monorail system, the proximal end opening of the inner tube is opened to the outside through a tube wall positioned in the longitudinal direction of the outer tube.
Preferably, the proximal end opening of the inner tube and the tube wall of the outer tube are hermetically sealed by heat.

Alternatively, the outer tube may include a first outer tube member and a second outer tube member joined to a proximal end of the first outer tube member. In this case, for example, the second outer tube member is made of a material having a higher hardness than the first outer tube member,
A reinforcing material may be contained (including adherence) only in the outer tube member. Alternatively, the second outer tube member may be a tapered tube in which the outer diameter is tapered from the distal end toward the proximal end. Further, only the second outer tube member may have an irregular cross section other than the circular cross section.

In this case, the second outer tube member has a flexural rigidity (E ^*) which is smaller than that of the first outer tube member ^.
It is preferable to have different materials or different cross-sectional shapes so that I; E ^* is the Young's modulus of the material, and I is the second moment of area.

In the above method for producing a balloon, at least 4
It is preferable that the tube is irradiated with an electron beam under a condition of 0 Mrad to crosslink the tube with an electron beam to form a crosslinked tube. Further, it is preferable to heat-treat the crosslinked tube at least at 90 ° C.

In the method of manufacturing the balloon portion, when the crosslinked tube is blow-molded, a primary blow pressure of 15 to 25 kgf / cm ^{2 is} applied to the mold, and at least one second before opening the mold, It is preferable to apply a secondary blow pressure of 5 to 8 kgf / cm ² .

[0018] The method for manufacturing a balloon catheter includes the step of using the above-mentioned balloon portion to attach a proximal end of the balloon portion to a distal end of an outer tube in which at least one balloon inflation lumen is formed along a longitudinal direction. A balloon portion proximal end joining step of joining the ends so that the balloon inflation lumen and the inside of the balloon portion communicate with each other, and into the inside of the balloon portion and the inside of the balloon inflation lumen of the outer tube. Extending the inner tube in the axial direction and joining the distal end of the inner tube to the distal end of the balloon so as to form a sealed expansion space inside the balloon; And

In the case where the balloon catheter is of the monorail type, in addition to the above steps, an inner tube is axially extended inside the balloon portion and inside a balloon expansion lumen of the outer tube, A withdrawal step of pulling out the proximal end of the inner tube to the outside of the outer tube through a through hole formed in a tube wall located in the middle of the outer tube in the axial direction; An outer tube wall of the inner tube located at a portion passing through a certain through hole, and a heat fusion step of thermally fusing an inner edge of the through hole; and the inner tube thermally fused in the heat fusion step Leaving the heat-sealed portion of the outer tube wall and the inner edge of the through hole, removing unnecessary portions of the inner tube located outside from the heat-sealed portion, and opening the proximal end opening of the inner tube,
Removing step of forming on the tube wall of the outer tube.

Further, when the outer tube of the balloon catheter comprises a first outer tube member and a second outer tube member joined to a proximal end of the first outer tube member, A step of joining the outer tube member and the second outer tube member.

In the method of manufacturing a balloon catheter according to the present invention, it is preferable that, in the heat-sealing step, a heat-sealing tube is used, a portion to be heat-sealed be covered with the heat-sealing tube, and heated. After heat fusion, it is preferable to remove the heat sealing tube. The heat sealing tube is not particularly limited, but for example, a fluororesin tube is used.

[0022]

The balloon catheter of the present invention generally has a higher breaking strength than a balloon obtained by blow molding at around the melting point of a crystalline polyethylene resin (110 to 115 ° C.). It can withstand high pressure for balloon expansion. For example, when used as a PTCA balloon catheter, safety when expanding a vascular stenosis portion is extremely excellent.

Further, the balloon used in the balloon catheter of the present invention can be blow-molded at a temperature significantly lower than the melting point of the crystalline polyethylene resin, for example. Thereby, the breaking strength of the balloon can be increased.

In the balloon catheter of the present invention, the outer tube is made up of a relatively flexible first outer tube member on the distal end side and a relatively rigid proximal end joined to the first outer tube. When configured with the side-made second outer tube member, the distal end side of the catheter tube becomes flexible,
The insertion characteristics in body cavities such as tortuous blood vessels are further improved.

In the present invention, the outer tube is formed of a first outer tube member having a circular cross section, and a second outer tube member made of fluorine resin having an elliptical cross section joined to a proximal end of the first outer tube member. When the outer tube has an oval cross-section on the proximal end side, when two or more balloon catheters are simultaneously inserted into a blood vessel, such as in a kissing method, a narrow intravascular space is formed. However, it can be inserted without burdening the blood vessels.

[0026] In the present invention, a proximal end opening of the inner tube is opened to the outside through a tube wall positioned in the longitudinal direction of the outer tube member, and a proximal end opening of the inner tube is provided. When a structure in which the tube wall of the outer tube member and the tube wall of the outer tube member are hermetically sealed is adopted, only the distal end of the balloon catheter has a so-called coaxial catheter tube structure. The lumen of the tube can be used as a guide wire insertion lumen, and the outer diameter of the catheter tube is easily reduced as compared with a conventional balloon catheter having a so-called double-lumen catheter tube.

Further, when the above aspect is adopted, in the balloon catheter of the present invention, the proximal end opening of the inner tube serving as the proximal end side outlet of the guide wire is formed in the longitudinal direction of the first outer tube member. It is only open to the outside through the tube wall positioned in the middle of the catheter tube, and there is no step over the entire length of the catheter tube, and the balloon catheter has excellent insertion characteristics. In addition, since it has a structure that does not easily kink, the balloon catheter has excellent pushing characteristics.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings. FIG. 1A is an overall configuration diagram of a balloon catheter according to one embodiment of the present invention, and FIG.
FIG. 1 is a sectional view taken along line IB-IB shown in FIG.
(C) is a cross-sectional view along the line IC-IC shown in FIG.
FIG. 1D is a sectional view taken along the line ID-ID shown in FIG. 1A, and FIG. 1E is a sectional view taken along the line IE-IE shown in FIG.

FIG. 2 is a longitudinal sectional view of a main part of the balloon catheter shown in FIG. 1 (A), and FIG. 3 (A) is a perspective view of a first outer tube and a balloon part showing a manufacturing process of the balloon catheter according to the present embodiment. FIG. 3B is a perspective view of a heat-sealing tube used in the manufacturing process of the balloon catheter.
4 (A) and 4 (B), FIG. 5 (A) and FIG.
6 (B), 6 (A), 6 (B) and 6 (C) are fragmentary perspective views showing the process of manufacturing the balloon catheter.

The balloon catheter 2 according to the present embodiment shown in FIG. 1 includes, for example, percutaneous coronary angioplasty (PTCA),
It is used in methods such as dilation of blood vessels such as limbs, dilation of the upper ureter, and renal vasodilation, and is used to dilate stenosis formed in blood vessels or other body cavities. In the following description, the balloon catheter 2 of the present embodiment is referred to as PTC.
A case where A is used will be described as an example.

The balloon catheter 2 for expansion according to the present embodiment
Is a so-called monorail type balloon catheter, which has a balloon portion 4, an outer tube 6 as a catheter tube, and a connector 8. The outer tube 6
The first outer tube member 6a is relatively flexible, and the second outer tube member 6b is relatively rigid and is joined to the first outer tube member 6a at the joint 9.

In this embodiment, the proximal end opening of the inner tube is opened to the outside through the tube wall located in the middle of the first outer tube member 6a in the longitudinal direction, and the proximal end opening of the inner tube is opened. By adopting a structure in which the portion and the tube wall of the first outer tube member 6a are heat-sealed in an airtight manner, only the distal end of the balloon catheter has a so-called coaxial catheter tube structure. is there.

In this embodiment, as shown in FIG. 1C, the outer cross-sectional shape of the second outer tube member 6b has an elliptical shape elongated in the Y-axis direction. The ratio (xm) between the maximum cross-sectional width xm of the catheter tube in the X-axis direction perpendicular to the Y-axis and the maximum cross-sectional width ym in the Y-axis direction
/ Ym) is in the range of 0.8 to 0.1, and the third lumen 24 having a semicircular cross section and the fourth lumen 26 having a circular cross section
Are formed separately along the Y-axis direction.

The semicircular cross-sectional area of the third lumen 24 is
It is sufficient that the cross-sectional area is sufficient to allow the balloon expansion pressure fluid to flow, and is not particularly limited.
08 to 0.20 mm ² . Also, the fourth lumen 2
The circular cross-sectional area of No. ⁶ is not particularly limited as long as it is a sufficient area for inserting the reinforcing rod 28 therein, but is preferably 0.05 to 0.5 mm ² , and more preferably 0.1 to 0.5 mm ² . 0.2 mm ² .

In this embodiment, the second outer tube member 6b
, The maximum cross-sectional width ym in the Y-axis direction is 0.6
It is preferably about 1.2 mm. Second outer tube member 6b
Is joined to the proximal end of the first outer tube member 6a having a circular cross section, so that the cross-sectional shape near the joint 9 is the same as the circular cross-sectional shape with the first outer tube member 6a. In order to make them coincide with each other, the cross-sectional shape gradually changes from the deformed cross section to the circular cross section toward the joint 9.

The third lumen 24 formed along the longitudinal direction of the second outer tube member 6b communicates with the first lumen 10 of the first outer tube member 6a, and through these, the expansion space of the balloon portion 4. To take fluid in and out. The fourth lumen 26 of the second outer tube 6b is a lumen for inserting the reinforcing rod 28, and communicates with the first lumen 10 of the first outer tube member 6a. It is closed at 8 and does not allow fluid to enter or exit. The proximal end of the second outer tube member 6c is connected to the connector 8, and a port is formed to communicate with the third lumen 24 of the second outer tube 6b. The port is a part that allows the pressure fluid to enter and exit, and does not communicate with the fourth lumen 26.

The reinforcing rod 28 shown in FIGS. 1B, 1C and 1F is inserted into the fourth lumen 26 of the second outer tube member 6b over its entire length, and its distal end is , Over the joint 9 with the first outer tube member 6a and protruding into the first lumen 10 of the first outer tube member 6a. The proximal end of the reinforcing rod 28 is circular in cross section, tapered from the middle toward the distal end, and further has a flat cross section at the distal end.
Its cross-sectional shape is gradually changing. The distal end of the reinforcing rod 28 having a flat cross section slightly crosses the proximal end opening 22 of the inner tube 12 slightly (preferably about 1 to 10 cm) as shown in FIGS. 1 (D) and 2. At the position, it is joined to the inner wall of the first outer tube member 6a by means such as heat fusion or adhesion.

The maximum outer diameter of the reinforcing rod 28 is the second outer diameter.
It is determined so that it can be inserted into the fourth lumen 26 of the outer tube member 6b, and is not particularly limited.
０．６0.6 mm.

The balloon portion 4 shown in FIGS. 1 and 2 is formed of a cylindrical film having both ends reduced in diameter.
Although not particularly limited, 15 to 300 μm, preferably 3
0 to 150 μm. The balloon portion 4 is not particularly limited as long as it is cylindrical, and may have a cylindrical or polygonal cylindrical shape.
The outer diameter of the balloon portion 4 when expanded is usually 1.5 to 1
It is about 0.0 mm, preferably 3 to 7 mm. The axial length of the balloon portion 4 is not particularly limited, but may be 15 to 15.
It is 50 mm, preferably 20 to 40 mm. The balloon portion 4 before being expanded is folded and wound around the inner tube 12, and has an outer diameter as small as possible.

As shown in FIG. 2, the first outer tube member 6
The proximal end 5 of the balloon portion 4 is joined to the outer periphery of the distal end of the balloon portion 4 by means such as heat fusion or adhesion, and the first lumen 10 of the first outer tube member 6a is It is designed to communicate with the internal expansion space. Balloon part 4
Is joined to the outer periphery of the distal end of the inner tube 14 by means such as heat fusion or adhesion, and the space for internal expansion of the balloon portion 4 is other than the first lumen 10. , Sealed to the outside. First outer tube member 6
The first lumen 10a is a passage for sending fluid into the internal expansion space of the balloon portion 4 to expand the balloon portion 4 or to extract fluid from the expansion space of the balloon portion 4 and to contract the balloon portion 4. is there.

As shown in FIG. 2, the inner tube 12 extends coaxially and axially in the expansion space of the balloon portion 4 and the inside of the distal end side first lumen 10 of the first outer tube member 6a. It has a catheter tube structure. Inner tube 12 located inside balloon portion 4
A contrast ring 15 is attached to the outer periphery of the body, and when the balloon catheter 2 is inserted into a living body, the position of the contrast ring 15 can be contrasted with X-rays or the like from outside the living body. Examples of the material of the contrast ring 15 include metals such as gold, platinum, and tungsten.

A second lumen 14 is formed inside the inner tube 12, and its distal end opening 20 opens at the distal end 7 of the balloon section 4. The proximal end opening 22 of the inner tube 12 is opened to the outside through a through-hole 21 in the tube wall located in the longitudinal direction of the first outer tube member 6a. Proximal end opening 2 of inner tube 12
The peripheral edge of 2 and the peripheral edge of the through hole 21 in the tube wall of the first outer tube member 6a are hermetically joined by a heat fusion method described later. The shape of the proximal end opening 22 of the inner tube 12 is not particularly limited, and may take various shapes such as a circle and an ellipse. In the present embodiment, as shown in FIG. It is an elliptical shape with the part cut diagonally. The second lumen 14 of the inner tube 12 is a guidewire insertion lumen through which a guidewire 42 shown in FIG. 2 for guiding the balloon catheter 2 into a body cavity is inserted.

The inner tube 12 is connected to the first outer tube member 6.
The first outer tube member 6a may be made of a synthetic resin that is harder than the first outer tube member 6a. The position where the proximal end opening 22 of the inner tube 12 opens outside the first outer tube member 6a is preferably a position of a length L1 from the distal end of the first outer tube member 6a, and the length L1 Is preferably 150 to 350
mm, more preferably 200 to 300 mm.

The outer diameter of the first outer tube member 6a is not particularly limited, but is preferably 0.5 to 5 mm, more preferably 0.5 to 1 mm. First outer tube member 6a
Is not particularly limited, but preferably 0.05 to
It is 0.5 mm, more preferably 0.1 to 0.2 mm.

The outer diameter of the inner tube 12 is determined so that a gap is formed between the inner tube 12 and the first outer tube member 6a, and is not particularly limited, but is preferably 0.3 to 3 mm, more preferably 0.3 to 3 mm. 0.8 mm. Inner tube 12
Is not particularly limited as long as it can penetrate the guide wire 42, and is, for example, 0.15 to 1.0 mm, and preferably 0.25 to 0.6 mm.

In this embodiment, in order to reinforce the strength of the first outer tube member 6a from the vicinity of the opening 22 to the proximal end side, as shown in FIG.
It may be disposed inside the first outer tube member 6a from the vicinity to the proximal end side. The proximal end of the reinforcing rod 28 has a circular cross-section, tapers from the middle toward the distal end, and has a cross-sectional shape at the distal end such that the reinforcing rod 28 has a flat cross-sectional shape. It is changing gradually. The distal end of the reinforcing rod 28, which has a flat cross-section, slightly (preferably 1) with the proximal end opening 22 of the inner tube 12, as shown in FIG.
(About 10 cm) at a position over the inner wall of the first outer tube member 6a by means of heat fusion or adhesion.

The reinforcing rod 28 is made of stainless steel,
It is made of a metal material such as copper, copper alloy, titanium, and titanium alloy, or a synthetic resin such as polyimide, polyamide, and polyethylene terephthalate. The maximum outer diameter of the reinforcing rod 28 is determined so as not to block the lumen 10 of the first outer tube member 6a, and is not particularly limited, but is preferably 0.3 to 0.6 mm.

The balloon portion 4 is made of a crystalline polyolefin resin. Specific examples include a polyethylene resin, a polypropylene resin, an ethylene-propylene copolymer resin, and a copolymer resin of ethylene and another α-olefin. Among them, polyethylene resins are preferable, and for example, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and the like are preferably used.

The first outer tube member 6a may be made of, for example, the same material as the balloon part 4, but is preferably made of a material having flexibility. For example, polyethylene, polyethylene terephthalate, polypropylene,
Ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride (PVC), cross-linked ethylene-vinyl acetate copolymer, polyurethane, polyamide, polyamide elastomer, polyimide, polyimide elastomer, polytetrafluoroethylene resin , Ethylene tetrafluoride-hexafluoropropylene copolymer resin, ethylene tetrafluoride-
Perfluoroalkyl vinyl ether copolymer resin, ethylene trifluoride resin, ethylene tetrafluoroethylene-ethylene copolymer resin, vinylidene fluoride resin, polyvinyl fluoride resin, silicone rubber, natural rubber, and the like. Among them, polyethylene, polyamide and polyimide are preferred. The hardness of the first outer tube member 6a is J
Those having an IS hardness of about 50A to 90A can be used.

The second outer tube member 6b is made of the same material as the first outer tube member. As the hardness of the second outer tube member 6b, one having a JIS hardness of about 50D to 75D can be used.

In this embodiment, the outer tube 6 composed of the first outer tube member 6a and the second outer tube member
Is preferably coated with a coating material made of a hydrophilic polymer substance having lubricity in a wet state.

Next, a method for manufacturing the balloon catheter 2 according to this embodiment will be described. First, a method of manufacturing the balloon will be described. The material used for the balloon portion of the present invention is, for example, a crystalline polyethylene resin, and the melting point of the material used in the present embodiment is 115 ° C. This is used to form a blow-molding original tube having dimensions designed in advance. The molding can be performed by, for example, an extrusion molding method, and the die temperature during extrusion is, for example, 200 to 300 ° C.
It is. The extruded tube immediately after being discharged from the die is cooled, for example, by passing it through a water bath (20 to 30 ° C.).

Next, the extruded tube is irradiated with an electron beam to prepare a polyethylene cross-linked tube (hereinafter, referred to as “parison”). The irradiation amount of the electron beam is, for example, 40 to 100 Mrad, preferably 50 to 70 Mrad.
It is. Thereafter, the crosslinked tube is, for example, 90-1
Heat treatment is performed at about 10 ° C. for 30 minutes to several hours. This heat treatment step eliminates molding distortion caused by extrusion molding.

The parison prepared through the above steps is shaped into a balloon by blow molding, for example, through the following steps. First, as shown in FIG. 7A, the upper and lower sides of the parison are fixed. The upper chuck seals completely to prevent pressure leakage, and the lower chuck does not collapse the lumen so that blow pressure is applied.

Next, the parison is blow-molded at a temperature lower than the melting point of the crystalline polyethylene resin which is the material of the parison. The temperature is, for example, lower than the melting point of the crystalline polyolefin-type resin by 10 ° C. or higher, preferably 20 ° C. or higher, and more preferably 30 ° C. to 6 ° C.
This is performed at a temperature in the range of a low temperature of about 0 ° C. In the present embodiment, the melting point of the polyethylene resin is 115 ° C., and the blow molding temperature of the parison is 80 ° C. If the temperature is too high, blow molding becomes easier, but the breaking strength of the balloon decreases. If the temperature is excessively low, a very high blow pressure is required to shape the balloon, which is not preferable. Also, balloons blow-molded on an excessively low temperature side are not preferable because of extreme shrinkage.

The blow molding is specifically performed by the following steps. In the present embodiment, for example, the parison fixed up and down is heated at about 80 ° C. for 120 minutes in advance and then stretched about 150 to 200% in the up and down direction. Next, at the same time as the parison was stretched, the two halves (heated to 80 ° C.) were closed so as to sandwich the parison, and then the first blow pressure was applied, In the present embodiment, it is held for 29 seconds. Next, the pressure is maintained at a blow pressure lower than the first blow pressure (hereinafter, referred to as “second blow pressure”) for 1 second, and then the mold is opened. If the mold is opened while maintaining the first blow pressure, the formed balloon will burst, so it is necessary to reduce the blow pressure to the second blow pressure immediately before the mold is opened. In the case of the present embodiment, the second
The blow pressure is set at a pressure of one half or less, preferably one third or less of the first blow pressure.

The gas introduced into the parison is not particularly limited. For example, nitrogen gas or the like can be used. The first blow pressure for inflating the parison is
For example, 10 to 30 kgf / cm ² , preferably 15 to
It is 25 kgf / cm ² . The second blow pressure is, for example, 3 to 10 kgf / cm ² , preferably 5 to 8 kg.
f / cm ² .

By the blow molding described above, the balloon is
For example, as shown in FIG.
And a portion 7f for joining with the balloon catheter.

The outer diameter of the balloon formed by blow molding is 1 atm or 6 atm by a laser outer diameter measuring device.
The outer diameter when applying a pressure of atm is measured. The thickness of the balloon is measured with a micro gauge.

The balloon formed by blow molding
The effective stretching ratio (cross-sectional area of cross-linked tube / cross-sectional area of balloon) from the cross-linked tube to the balloon needs to be less than 500%, preferably 350% or less. An excessively large effective stretching ratio is not preferable because the breaking strength of the balloon is extremely reduced.

The breaking strength of the balloon was determined by applying a pressure of 1 atm to the balloon in water at 37 ° C. and holding it for 15 seconds, followed by an additional pressure of 1 atm and holding the balloon for 15 seconds. This step was repeated until the balloon burst. The burst pressure (burst pressure unit: atm) is measured as the breaking strength.

Table 1 shows the breaking strength of the balloon blow-molded by the method described above. In addition, the breaking strength of the balloon obtained by performing blow molding at 113 ° C. using the same polyethylene resin crosslinked tube is shown in Table 1 as a comparative example. In this case, since the first blow pressure is 2.9 kgf / cm ² , the mold can be opened without going through the step of reducing the blow pressure to the second blow pressure as described above.

From the results shown in Table 1, the balloons used in the present invention (Examples 1, 2, 4 and 6) were blow molded at 80 ° C., which is 35 ° C. lower than the melting point of 115 ° C. of the polyethylene resin. By doing so, it can be seen that the breaking strength of the balloon is greatly increased. On the other hand, when the crosslinked tube is blow-molded at 113 ° C., which is slightly lower than the melting point of 115 ° C. of the polyethylene resin (Comparative Example), the breaking strength of the obtained balloon is insufficient.

The balloon used in the present invention (Examples 3, 4 and 5) was blow-molded at a temperature in the range of 90 to 70 ° C. to form a balloon near the melting point of the polyethylene resin (113 ° C.). It can be seen that the blow strength of the balloon is higher than that of the blow molded in Example).

[0065]

[Table 1]

A method of manufacturing the balloon catheter of the present embodiment using the balloon blow-molded through the above steps will be described. As shown in FIG. 3A, first, the first outer tube member 6a and the balloon portion 4 are prepared, and the cylindrical proximal end of the balloon portion 4 is provided around the outer periphery of the distal end of the first outer tube member 6a. The part 5 is covered, and the part is heat-sealed. Next, the first
On the tube wall at a predetermined position in the axial direction of the outer tube member 6a,
A through-hole 21 is formed so that the inner tube 12 to be described later can pass through. Also, a heat sealing tube 50 shown in FIG. 3B is prepared.

The inner diameter of the heat sealing tube 50 is slightly larger than the outer diameter of the first outer tube member 6a. As the tube 50 for heat sealing, for example, a fluororesin tube is used, and its axial length is, for example, about 20 mm. Tube 50 for heat sealing
A cut 52 having a length of about 3 mm is formed at one end in the axial direction.

Next, as shown in FIG. 4A, the inner tube 12 to which the contrast ring 15 is mounted is prepared, and the inner tube 12 is integrated with the lumen of the inner tube 12 through the wire-shaped mandrel 54. The inner tube 12 with the mandrel 54 integrated therethrough is passed through the through-hole 21 into the inner lumen of the first outer tube member 6a, and the distal end of the inner tube 12 is projected from the distal end 7 of the balloon portion 4 to enhance contrast. The ring 15 is located at the center of the balloon section 4. Before and after that, the heat sealing tube 50 is positioned on the outer periphery of the first outer tube member 6a.

Thereafter, the heat sealing mandrel 56 is inserted into the inside from the proximal end of the first outer tube member 6a,
The tip of the mandrel 56 is positioned near the through hole 21 to prevent the first outer tube member 6a from being crushed near the through hole 21. The proximal end of the mandrel 56 has an outer diameter substantially equal to or less than the inner diameter of the first outer tube member 6 a, and the distal end thereof has an axial recess 57 so as to receive the outer circumference of the inner tube 12. It is formed. Next, the heat-sealing tube 50 is moved axially around the outer periphery of the first outer tube member 6 a, and the heat-sealing tube 50 is moved to the outer periphery of the first outer tube member 6 a near the through hole 21 and the through hole 21. And the outside of the inner tube 12 that protrudes from the inside. After that, using a heat-sealing mold, the heat is pressed and heated from the outside of the heat-sealing tube 50, and the hole edge of the through-hole 21 and the outer tube wall of the inner tube 12 are heat-sealed. The heating temperature is not particularly limited, but is preferably 100 to 300 ° C, and particularly preferably 150 to 25 ° C.
0 ° C.

Thereafter, the mandrels 54 and 56 are taken out, and the notches 5 of the heat sealing tube 50 are cut out.
2 to tear the tube 50 in the axial direction,
From the outer periphery of the first outer tube member 6a. Thereafter, as shown in FIGS. 5A and 5B, the outer tube wall of the inner tube 12 and the through-hole 21 which are heat-sealed in the heat-sealing step.
The unnecessary portion of the inner tube 12 located outside from the heat-sealed portion is cut and removed by a cutter or the like, while leaving the heat-sealed portion with the inner edge of the inner tube. As a result, the proximal end opening 22 of the inner tube 12 is formed to open outside the tube wall of the first outer tube member 6a. The proximal end opening 22 has a substantially elliptical shape in this example. However, in FIG. 5, although the ellipse is quite flat, it is actually an ellipse close to a circle.
Note that before, after, or simultaneously with these steps, FIG.
The distal end of the inner tube 12 is heat-sealed to the distal end of the balloon portion 4 by a similar heat sealing method and cut to a predetermined length.

That is, as shown in FIGS. 5A and 5B, a heat-sealed portion between the outer tube wall of the inner tube 12 and the inner edge of the through hole 21 which has been heat-sealed in the heat-sealing step is left. Then, after the unnecessary portion of the inner tube 12 located outside from the heat-sealed portion is cut and removed with a cutter or the like, the process shown in FIG. 6 is then performed. As shown in FIG. 6A, the outer periphery of the second outer tube member 6c is covered with another heat sealing tube 58 having the same material and structure as the heat sealing tube 50 shown in FIG. The distal end of the second outer tube member 6c is pushed into the lumen at the proximal end of the outer tube member 6a. Thereafter, as shown in FIG.
The mandrel 60 is inserted into the third lumen 24 of the outer tube member 6c along the axial direction, and its tip is protruded to the inside of the first outer tube member 6a. Before, after or at the same time, the fourth lumen 26 of the second outer tube member 6c
The reinforcing rod 28 is inserted along the axial direction into the inside of the first outer tube member 6a, and its distal end is positioned below the proximal end opening 22 formed on the outer periphery of the first outer tube member 6a.

Thereafter, as shown in FIG. 6C, the heat-sealing tube 58 is moved in the axial direction, and the heat-sealing tube 58 is used to connect the first outer tube member 6a and the second outer tube member 6c. The joint 9 is covered, and heat fusion is performed using a mold under the same heat sealing conditions as those described above.

Thereafter, the heat-sealing tube 58 is removed and the mandrel 60 is removed, and the connector 8 shown in FIG. 1 is joined to the proximal end of the second outer tube member 6c by means such as heat fusion. Thereafter, if necessary, the outer peripheral surface of the outer tube 6A is coated with a coating made of a hydrophilic polymer substance having lubricity in a wet state, and the balloon catheter 2 shown in FIG. 4 is obtained.

[0074]

Thus, according to the present invention, there is provided a balloon catheter having improved balloon breaking strength. The polyethylene resin balloon used for the balloon catheter of the present invention usually has a higher breaking strength than a balloon obtained by blow molding near the melting point of the crystalline polyethylene resin (110 ° C.). Can withstand high pressure for expansion, such as PTC
When used as an A-balloon catheter, the safety when dilating a vascular stenosis part is extremely excellent.

Further, the balloon used in the balloon catheter of the present invention can be blow-molded at a temperature significantly lower than, for example, the melting point of the crystalline polyethylene resin. Thereby, the breaking strength of the balloon can be increased.

[Brief description of the drawings]

FIG. 1 (A) is an overall configuration diagram of a balloon catheter according to an embodiment of the present invention, and FIG. 1 (B) is FIG. 1 (A).
1 (C) is a sectional view taken along line IB-IB shown in FIG.
1A is a cross-sectional view taken along the line IC-IC, FIG. 1D is a cross-sectional view taken along the line ID-ID shown in FIG.
FIG. 1E is a cross-sectional view taken along the line IE-IE shown in FIG.
FIG. 1F is a side view of a reinforcing rod inserted into the catheter tube of the balloon catheter.

FIG. 2 is a longitudinal sectional view of a main part of the balloon catheter shown in FIG. 1 (A).

FIG. 3A is a perspective view of an outer tube and a balloon portion showing a manufacturing process of the balloon catheter according to the present embodiment, and FIG. 3B is a perspective view of a heat sealing tube used in the manufacturing process of the balloon catheter. FIG.

4 (A) and 4 (B) are perspective views of a main part showing a process of manufacturing a balloon catheter.

5 (A) and 5 (B) are perspective views of a main part showing a manufacturing process of a balloon catheter.

6 (A) and 6 (B) are perspective views of main parts showing a step of joining a first outer tube member and a second outer tube member in the process of manufacturing the balloon catheter shown in FIG. is there.

FIG. 7A is a sectional view of a main part when a parison is fixed to a blow molding machine, and FIG. 7B is a perspective view of a balloon obtained by blow molding.

[Explanation of symbols]

 2 balloon balloon 4 balloon portion 6 outer tube 6a first outer tube member 6b second outer tube member 8 connector 10 first lumen 12 inner tube 14 second lumen 20 distal end opening 21 ... Through-hole 22 ... Proximal end opening 24 ... Third lumen 26 ... Fourth lumen 28 ... Reinforcing rod 28a ... Reinforcing member 50, 58 ... Heat sealing tube 54, 56, 60 ... Mandrel 7a ... Parison 7b ... Upper part Chuck 7c: Lower chuck 7d: Heater 7e: Balloon body 7f: Joint with balloon catheter body

Claims (2)

[Claims] 1. An outer tube having at least one balloon inflation lumen formed along a longitudinal direction, and a proximal end of a balloon portion joined to a distal end of the outer tube. A balloon portion that communicates with the lumen, and a distal end portion of the balloon portion is joined to a distal end portion of the inner tube so as to form a sealed expansion space inside the balloon portion; A balloon catheter having an inner tube extending in the axial direction inside the inner tube and inside the balloon expansion lumen of the outer tube, wherein the balloon portion is blown using a crosslinked tube made of a crystalline polyolefin resin. The blow molding is performed at a temperature lower than the melting point of the crystalline polyolefin resin by 10 ° C. or more. Balloon catheter, characterized in that it. 2. A step of preparing a cross-linked tube by electron beam cross-linking a tube made of a crystalline polyolefin-based resin, wherein the cross-linking tube is firstly formed at a temperature lower than the melting point of the crystalline polyolefin-based resin by 10 ° C. or more. Applying a blow pressure, and then applying a secondary blow pressure, which is lower than the primary blow pressure, to the cross-linking tube to prepare a balloon portion, wherein at least one balloon inflation lumen extends in a longitudinal direction. A proximal end portion of the balloon portion that joins the proximal end portion of the balloon portion to the distal end portion of the outer tube formed along the balloon so that the lumen for balloon expansion communicates with the inside of the balloon portion. A joining step; extending the inner tube in the axial direction inside the balloon portion and inside the balloon expansion lumen of the outer tube; A distal end portion, so as to form an extended space which is sealed to the inside of the balloon portion, the manufacturing method of a balloon catheter and a step of bonding the distal end of the balloon portion.