JP2012187147A - Molding mold of balloon for balloon catheter and molding method of balloon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balloon in which a balloon straight tube part and a balloon tapered part are uniformly thin even while having sufficient pressure resistance, and which has flexibility for facilitating insertion to the narrowed section of a bent blood vessel.SOLUTION: In a mold 10 for molding the balloon, the friction coefficient of a mold inner wall 30 equivalent to the straight tube part of the balloon or a part of it is made larger than the friction coefficient of a mold inner wall equivalent to the tapered part of the balloon or the tapered part and a part reaching a part of the straight tube part continued to the tapered part.

Description

  The present invention relates to a balloon catheter used for medical applications, and more particularly, percutaneous angioplasty (PTA: Percutaneous Transluminal Coronary, PTCA) when performing peripheral angioplasty, coronary artery shaping, valvular shaping, and the like. The present invention relates to a balloon molding method for a balloon catheter used in Angioplasty and the like, and its mold.

  Percutaneous angioplasty is a technique widely used for the purpose of restoring or improving blood flow in coronary arteries, peripheral blood vessels, etc. by expanding and treating stenosis or occlusion in the lumen of blood vessels. As shown in FIG. 2, a balloon catheter used for percutaneous angioplasty is formed by joining a balloon 1 which can be inflated / deflated by adjusting the internal pressure to the distal end portion of a shaft 2. Generally, a lumen (guide wire lumen) through which the guide wire is inserted and a lumen (inflation lumen) for supplying a pressure fluid for adjusting the balloon internal pressure are provided along the long axis direction of the shaft.

  General examples of percutaneous angioplasty using a balloon catheter are as follows. First, a guide catheter is inserted from a puncture site such as the femoral artery, brachial artery, and radial artery, and the distal end thereof is disposed at the entrance of the coronary artery via the aorta. Next, the guide wire inserted through the guide wire lumen is advanced beyond the stenosis site of the coronary artery, and a balloon catheter is inserted along the guide wire to match the balloon with the stenosis. Next, using a device such as an inflator, the stenosis is expanded by supplying pressure fluid to the balloon via the inflation lumen and inflating the balloon. After dilatation treatment of the stenosis, PTCA is completed by decompressing and deflating the balloon and removing it from the body. In this operation example, an example of using a PTCA balloon catheter has been described. However, the balloon catheter is widely applied to dilatation treatment in other blood vessel lumens and body cavities such as the periphery.

  As described above, balloon catheters are shipped to the market under strict quality control because of their important role of expanding a stenosis in a blood vessel. The quality characteristics include dimensional characteristics such as the outer diameter and length of the balloon, appearance characteristics such as scratches and foreign matters, pressure resistance characteristics, and the like when referring only to the balloon.

  In particular, a high compressive strength is required to expand a calcified hard stenosis. In addition, high flexibility is required in order to locate the bent stenosis. In addition, in order to be positioned at a stenosis site having a very high stenosis degree of 99%, not only flexibility but also a sufficiently thin balloon is required. When these characteristics are combined, the balloon is required to be thin, to have high film strength, and to have high flexibility.

  As a method for forming the balloon 1, as shown in FIG. 3, a resin tube-shaped parison 20 that can be stretched is heated in the mold 30 and biaxially stretched in the axial direction and the radial direction. As shown in FIG. 1, the balloon 1 formed by such a method includes a balloon straight tube portion 1a, a balloon taper portion 1b provided before and after the straight tube portion, and a balloon provided before and after the balloon taper portion. The joint portion 1c is composed of a non-molded portion 1d that is not molded by the outer mold.

  As shown in FIG. 4, the balloon formed by the method as shown in FIG. 3 has a thin film thickness at the central portion of the balloon straight tube portion 1a, and the balloon taper portion has a large film thickness. For this reason, when the balloon is folded, the balloon taper portion is thick because the film thickness is hard, the balloon taper portion is wrinkled and squared, the balloon cannot be folded small, and it is difficult to pass through the stenosis portion of the blood vessel. Become.

  Further, if the balloon taper portion is further reduced in the axial direction in order to make the balloon taper portion thinner, the film thickness of the central portion of the balloon straight tube portion 1a becomes extremely thin, and even if the balloon is ruptured or formed during blow molding, the pressure resistance of the balloon itself is reduced. As a result, various methods have been disclosed as countermeasures.

  For example, Patent Document 1 discloses a method of blow-molding a tube-shaped parison having a thick film at the center with respect to the film thickness at both ends. Since the process to process is added, there exists a fault to which cost becomes high or a yield worsens.

  Further, Patent Document 2 discloses a method of removing a balloon taper portion with a laser to make it thinner, but since post-processing of laser processing is added, an expensive laser processing apparatus is required, resulting in an increase in cost or reduction. There is a disadvantage that the rate becomes worse.

  Further, Patent Document 3 discloses a method of reducing the thickness of the tapered portion by redrawing the balloon tapered portion after forming the balloon, but there is a disadvantage that the cost is increased or the yield is deteriorated for the same reason as described above. .

JP-A-8-38618 JP-A-9-192227 Japanese Patent No. 2555298

  Therefore, in view of the above problems, the present invention intends to solve the problem that the balloon straight tube portion and the balloon taper portion are uniformly thin while having sufficient pressure resistance, and the bent blood vessel is inserted into the narrowed portion. Another object of the present invention is to provide a balloon molding die capable of easily and inexpensively manufacturing a balloon having flexibility that facilitates the above.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, and as a result, completed the present invention. That is, according to the present invention, in a mold for forming a balloon catheter for medical use having a tapered portion and a straight tube portion, the friction coefficient of the inner wall of the mold corresponding to the straight tube portion of the balloon or a part thereof is The present invention relates to a balloon molding die characterized by being larger than a friction coefficient of a die inner wall corresponding to a taper portion or a portion reaching a taper portion and a part of a straight pipe portion continuous with the taper portion.

  Further, the present invention is characterized in that the surface of the balloon is roughened by blasting the inner wall of the mold corresponding to a straight tube portion of the balloon or a part thereof by blowing glass beads, metal powder or the like with compressed air. It relates to a mold.

  In addition, the present invention is characterized in that the inner wall of the mold corresponding to the taper portion of the balloon or a portion extending to the taper portion and a part of the straight pipe portion continuous with the taper portion is treated with fluorine coating or the like for improving slipperiness. The present invention relates to the balloon molding die.

  Further, the present invention is the above-described balloon molding die, wherein the length Lb of the inner wall of the die corresponding to the straight tube portion of the balloon, the diameter Db of the straight tube portion of the balloon, the diameter Dp of the parison, the friction coefficient of the inner wall of the die. The present invention relates to a balloon molding die characterized in that different axial lengths Lr have a relationship of Lb / Lr <Db / Dp.

  The present invention also relates to a method for forming a balloon for a medical use balloon catheter having a tapered portion and a straight tube portion, the portion corresponding to the straight tube portion of the balloon, or a part of the inner wall of the molding die. The present invention relates to a method for forming a balloon, wherein a molding die having a friction coefficient larger than a friction coefficient of a portion corresponding to a tapered portion of the balloon or a portion reaching the tapered portion and a part of the straight pipe portion continuous with the tapered portion is used. .

  According to the balloon molding die of the present invention, it is possible to obtain a balloon having a uniform film thickness at the straight tube portion and the tapered portion of the balloon.

  According to the balloon molding die of the present invention, a balloon having a uniform film thickness can be molded at low cost without post-processing such as cutting or redrawing.

It is a figure explaining the form of the balloon after a general shaping | molding. It is a perspective view explaining a general balloon catheter. It is a figure explaining shaping | molding of a general balloon. It is a figure explaining shaping | molding of a general balloon. It is a figure explaining shaping | molding of a general balloon. It is a figure explaining shaping | molding of a general balloon. It is sectional drawing of the balloon shape | molded with the conventional metal mold | die. It is sectional drawing of the balloon shape | molded with the conventional metal mold | die. It is sectional drawing of the balloon shape | molded with the metal mold | die of this invention. It is a figure explaining shaping | molding of the balloon using the metal mold | die of this invention. It is a figure explaining shaping | molding of the balloon using the metal mold | die of this invention. It is a figure explaining shaping | molding of the balloon using the metal mold | die of this invention. It is a figure explaining another embodiment of the metal mold | die of this invention. It is a figure explaining another embodiment of the metal mold | die of this invention. It is a figure explaining another embodiment of the metal mold | die of this invention.

  A conventional balloon molding method that has been conventionally performed will be described in detail below.

  First, as shown in FIG. 3a, a tube-like parison 20 is set in a mold 10, and both ends or one side of the parison are sealed while being heated in the mold to introduce a compressed gas.

  The heating profile of the mold is controlled so that the inner wall of the mold corresponding to the straight tube portion of the balloon becomes hotter than the portion corresponding to the tapered portion, and the central portion of the parison becomes softer as shown in FIG. 3b. It begins to expand from the center. Then, as shown in FIG. 3c, the compressed gas is continuously introduced while the parison is stretched in the axial direction at an appropriate timing to obtain a desired balloon as shown in FIG. 3d.

  However, as shown in FIG. 3b, for example, the central portion of the expanded parison is heated by contacting the inner wall of the mold, and the resin is softened and is also stretched in the axial direction together with the axial stretching force. Subsequently, the tapered portions at both ends of the balloon are gradually expanded and stretched in the axial direction.

  As a result, the molded balloon has a thin film thickness of the straight tube portion of the balloon and a thick film thickness of the tapered portion as shown in FIG. On the other hand, if the film is stretched too much to simply reduce the film thickness, the central portion of the straight tube portion of the balloon becomes thin as shown in FIG.

  These causes are that the outer diameter of the balloon taper portion differs depending on the position in the axial direction, the elongation rate due to stretching in the circumferential direction of the parison is different, and the outer diameter of the balloon taper portion is smaller in the axial direction of stretching. The friction of the part becomes a resistance force, and the axial stretching is not sufficiently transmitted.

  Next, an embodiment of the mold of the present invention and a molding method will be described with reference to FIG. As shown in FIG. 7a, the balloon molding die of the present invention has a friction coefficient of a part 30 of the mold inner wall of the mold inner wall 2A corresponding to the balloon straight tube portion as compared with the other mold inner walls. Is also a bigger one. When the parison 20 set in the mold 10 is heated inside the mold and both ends or one side of the parison are sealed, and the compressed gas is introduced from the other end, the parison expands in the circumferential direction, and almost simultaneously However, when the parison expands in the circumferential direction and contacts the inner wall of the mold, the inner wall of the mold has a large friction, so the contacted parison portion is not stretched in the axial direction. The parison that is not touching is stretched.

  By doing so, the parison in contact with the inner wall of the mold is not stretched, and a balloon having a uniform film thickness can be obtained.

  An embodiment of a molding method using the balloon molding die of the present invention will be described with reference to FIG. 7c. In FIG. 7c, an example in which the portion 30 having a large friction coefficient is provided in the central portion of the mold is shown, but it may be shifted to the distal side or the proximal side depending on the intended characteristics of the balloon.

  In FIG. 7c, the straight tube portion length of the balloon molding die is denoted by Lb, the straight tube portion diameter is denoted by Db, the parison diameter is denoted by Dp, and the axial length of the portion 30 having a large friction coefficient on the inner wall of the mold is denoted by Lr. is doing. In the present invention, these values are not particularly limited, but when the relational expression Lb / Lr <Db / Dp is satisfied, a balloon having a more uniform membrane pressure can be obtained.

  In the present invention, as a processing method for increasing the friction coefficient of the surface of the inner wall of the mold, there is a method of making the surface of the inner wall of the mold uneven. For example, the friction coefficient of the part corresponding to the straight tube part of the balloon or a part of the inner wall of the mold can be determined by a method such as blasting by blowing glass powder or metal powder together with compressed air, electric discharge machining, cutting or polishing. The friction coefficient of the inner wall of the mold 30 of the taper portion or the portion 30 corresponding to the taper portion and a part of the straight pipe portion continuous with the taper portion can be made larger. As for the material of the mold, a normal mold material such as SUS, aluminum, brass and the like can be mentioned, but is not limited thereto.

  In the present invention, the friction coefficient of the portion having a large friction coefficient may be appropriately set according to the target balloon shape, and is not particularly limited, but can be expressed by the surface roughness Rz. In the case of a balloon mold for a balloon catheter for PTCA or PTA use, the surface roughness Rz is preferably 4 μm or more, and preferably 32 μm or less. The surface roughness can be changed depending on the blasting conditions. For example, with glass beads (# 100 mesh), compressed air (4.5 KPa), irradiation distance (140 mm), and time (60 seconds), the surface roughness is 4 μm, alumina (# 24 mesh), compressed air (4.5 KPa) The irradiation distance (140 mm) and time (120 seconds) are 32 μm.

  In addition, as described above, rather than increasing the coefficient of friction of the inner wall of the mold, the sliding property of the inner wall of the mold at the taper part of the balloon or the part corresponding to the taper part and a part of the straight pipe part continuous therewith is improved. By doing so, the friction coefficient of the straight tube portion of the balloon or a part of the inner wall of the mold may be relatively increased. FIG. 8 a shows an embodiment in which a portion 31 having a low friction coefficient is provided in a portion corresponding to a tapered portion of the balloon and a portion of the straight pipe portion continuous therewith. Examples of the method for reducing the friction coefficient of the inner wall of the mold include, but are not limited to, polishing, fluorine coating, and application of a release agent containing a fluororesin.

  Further, as shown in FIG. 8b, the constituent material of the balloon molding die is changed to a material 32 having a large friction coefficient in a portion corresponding to the straight tube portion of the balloon and a portion corresponding to the straight tube portion including the tapered portion. It is also effective to change the position, and as shown in FIG. 8c, a member 33 made of a material having a large friction coefficient may be embedded in a part of the portion corresponding to the straight tube portion of the balloon.

  The raw material of the balloon that can be used in the balloon molding die of the present invention is not particularly limited as long as it is a thermoplastic resin. Polyolefin, polyamide, polyurethane, polyester, polyolefin elastomer, polyamide elastomer, polyurethane All types of thermoplastic resins such as polyester elastomers and polyester elastomers can be used, but polyamide elastomers and polyester elastomers are preferred in terms of high pressure resistance and a certain degree of flexibility. Most preferred are elastomers.

  Hereinafter, the present invention will be described in more detail based on examples and comparative examples, but these do not limit the present invention in any way.

  An embodiment of the present invention will be described mainly with reference to FIG.

  A polyamide-based elastomer PEBAX7233 (manufactured by Elf Atchem) was extruded by a predetermined method to produce a tubular parison having an outer diameter of 0.72 mm and an inner diameter of 0.40 mm.

Mold used in the balloon forming the diameter of the portion corresponding to the balloon straight tube part using an axial of 15mm mold length in 2.5 mm, over the entire length of the portion corresponding to the balloon straight tube part # The inner wall of the mold was roughened by a blast treatment in which 60 mesh glass beads were sprayed with compressed air of 4.5 KPa at an irradiation distance of 140 mm for 120 seconds.

  Then, the tubular parison is inserted into the balloon mold, and the mold is inserted into an apparatus having a mechanism capable of individually heating the central part of the mold and both ends of the mold with an electric heater and individually cooling with water. When the temperature of the mold center was heated to 90 ° C., the temperature of the mold end was 60 ° C. due to heat transfer from the mold center.

  Then, one side of the parison is sealed, and pressurized nitrogen is blown from the other side to expand in the circumferential direction. At the same time, both sides of the parison are stretched 15 mm each in the axial direction. Next, water is poured into the pipe at the center of the mold and cooled to 40 ° C., both ends of the mold are heated to 90 ° C. by controlling an electric heater, and both ends of the parison are stretched by 5 mm each, The central part of the mold was heated to 120 ° C. and pressurized nitrogen was blown into the parison to expand it again. At this time, the temperature at both ends of the mold was 80 ° C. due to heat transfer from the center of the mold.

  Thereafter, the center of the mold and both ends of the mold were cooled, and the balloon was taken out from the mold.

  The obtained balloon had a thickness of 18.0 μm ± 1 μm over the entire straight tube portion of the balloon, and the pressure resistance was measured and found to be 24.8 atm.

Comparative example

  The same parison as that used in Example 1 was inserted into a die that was not subjected to blasting, in which the diameter corresponding to the straight tube portion of the balloon was 2.5 mm and the axial length was 15 mm. At this time, the mold was inserted into a device equipped with a mechanism capable of individually heating the center and both ends of the mold with an electric heater and individually cooling with water, and the temperature of the mold center was heated to 90 ° C. The temperature at the mold end was 60 ° C. due to heat transfer from the center of the mold.

  Then, one side of the parison is sealed, and pressurized nitrogen is blown from the other side to expand in the circumferential direction. At the same time, both sides of the parison are stretched 15 mm each in the axial direction. Next, water is poured into the pipe at the center of the mold and cooled to 40 ° C., both ends of the mold are heated to 90 ° C. by controlling an electric heater, and both ends of the parison are stretched by 5 mm each, The central part of the mold was heated to 120 ° C. and pressurized nitrogen was blown into the parison to expand it again. At this time, the temperature at both ends of the mold was 80 ° C. due to heat transfer from the center of the mold.

  Thereafter, the center of the mold and both ends of the mold were cooled, and the balloon was taken out from the mold.

  The obtained balloon had a thickness of 16.9 μm at the central portion of the straight tube portion of the balloon and 17.7 μm in the vicinity of the tapered portion of the straight tube portion. As a result of measuring the pressure resistance, it was 21.3 atm.

1. Balloon 1a. Balloon straight tube section 1b. Balloon taper part 1c. Balloon joint 1d. Unformed part 10. Mold 20. Tubular parison 30. A part where the friction coefficient of the inner wall of the mold is increased 31. Part with low coefficient of friction 32. Material with a high coefficient of friction 33. Material with a high coefficient of friction

Claims (5)

In a mold for forming a balloon catheter for a medical use balloon catheter having a taper portion and a straight tube portion, the friction coefficient of the inner wall of the die corresponding to the straight tube portion of the balloon or a part of the balloon is tapered or tapered. A balloon molding die characterized by being larger than the friction coefficient of the inner wall of the die corresponding to a portion reaching a part of the straight pipe portion continuous with the portion. 2. The balloon according to claim 1, wherein the inner wall of the mold corresponding to a straight tube part of the balloon or a part thereof is subjected to blasting by blowing glass beads or metal powder with compressed air to roughen the surface. Molding mold. The inner wall of the mold corresponding to the taper portion of the balloon or a portion extending to the taper portion and a part of the straight pipe portion continuous with the taper portion is treated with fluorine coating or the like for improving slipperiness. The balloon molding die according to 2. The balloon molding die according to any one of claims 1 to 3, wherein the length Lb of the inner wall of the die corresponding to the straight tube portion of the balloon, the diameter Db of the straight tube portion of the balloon, the diameter Dp of the parison, the die A balloon molding die characterized in that the axial length Lr having different friction coefficients of the inner wall has a relationship of Lb / Lr <Db / Dp. A method for forming a balloon for a balloon catheter for medical use having a tapered portion and a straight tube portion, wherein a portion corresponding to the straight tube portion of the balloon or a coefficient of friction of a portion of the inner wall of the molding die is a balloon. A method for forming a balloon, comprising using a molding die having a larger friction coefficient than a tapered portion or a portion corresponding to a portion extending to the tapered portion and a portion of a straight pipe portion continuous with the tapered portion.

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