JP3471949B2 - Dilatation catheter and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dilatation catheter useful for a medical vasodilation method such as a percutaneous percutaneous insertion / expansion of a dilatation catheter equipped with a balloon.

[0002] More specifically, catheters equipped with flexible balloons such as conventional polyolefin balloons are generally used for running in blood vessels that are bent and highly stenotic.
A relatively low level of pressure resistance is exhibited. On the other hand, attempts to improve the pressure resistance have caused drawbacks such as an increase in balloon hardness and impaired flexibility. The present invention has a relatively small film thickness, and flexibility and pressure resistance are highly balanced,
The present invention relates to a method of providing an excellent balloon having a relatively large expansion area.

[0003]

2. Description of the Related Art A technique for percutaneously inserting and expanding a catheter into a blood vessel without performing a surgical operation is generally carried out for treating a lesion involving a blood vessel, and such a vasodilation operation is performed. At this time, guiding catheters, dilatation catheters, etc. are generally used.

A representative example of a conventional balloon manufacturing method for use in dilatation catheters is US Pat. No. 4,093,484.
No. 4154244 and No. 4254774. Balloons can be made from various known polymeric materials that are generally thermoplastic. Among the known polymeric materials described in the above patents, polyurethane; polyvinyl chloride; thermoplastic elastomers; silicon carbonate copolymers; ethylene vinyl acetate copolymers; ethylene-butylene-styrene block copolymers; polystyrene; acrylonitrile copolymers. Various polyolefins such as polyethylene and polypropylene; polyethylene terephthalate and polyester copolymers; thermoplastic rubber; polyamide; polytetrafluoroethylene.

Among these, the balloons used for the dilatation catheter are required to have various characteristics depending on the state of the lesion, but a common requirement is to improve the safety of the dilatation catheter. However, there is a demand for a balloon having a high withstand voltage and a characteristic that the compliance gradually decreases toward the high pressure side. Also,
In the procedure applied to a blood vessel with more advanced stenosis, there is a demand for a balloon that is flexible, has excellent traveling properties, and has high safety. The term "blood vessel" used in the present invention is meant to include not only coronary blood vessels but also all blood vessels including coronary blood vessels, such as peripheral blood vessels.

The performance and function of the balloon of such a dilatation catheter are required to have various characteristics as described above depending on the state of the lesion. Polyethylene terephthalate type balloons are generally useful as balloons with high pressure resistance and no compliance or small size (eg, Japanese Patent Publication No. 63-26).
No. 655). However, this type of balloon
Too hard to use to dilate blood vessels with flexion and severe stenosis,
It cannot exhibit sufficient trackability. In addition, a polyamide (nylon) -based balloon can be provided as a semi-compliant balloon having a relatively high pressure resistance as compared with a polyolefin or the like (eg, JP-A-3-5746).
It has been pointed out that (2, etc.) still tends to be a little too stiff when applied to blood vessels that are extremely bent and severely stenotic, and blood vessels that are more peripheral. In addition, except for extremely hard lesions such as calcification, for general lesions, an excellent balloon having a relatively wide dilatation region is often demanded. That is, a plurality of catheters having different balloon sizes are used according to the degree of expansion of a lesion in a substantially expanded region used as a dilatation catheter. Larger balloons can achieve the intended expansion with a smaller number of catheters, and in recent years, there has been an increasing demand for high compliant balloons.

Therefore, in this percutaneous angioplasty, in the case of application to a blood vessel smaller than a peripheral blood vessel, there is an increasing demand for characteristics such as a flexible tip portion including a balloon portion and high compliance. In this sense, it is considered that polyolefin balloons such as polyethylene are suitable. However, since polyolefin-based materials generally have relatively low pressure resistance, there has been a concern that balloons may burst during the procedure.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a dilatation catheter equipped with a balloon having physical properties superior to those of the conventionally known polyolefin-based balloons, and a suitable production therefor. It is intended to provide the law. Thus, the object of the present invention is to maintain the flexibility of the polyolefin balloons conventionally used,
An object of the present invention is to provide a dilating catheter having a highly balanced balloon which is flexible and has high compliance, and which is thinner and has a higher dilatation strength. In addition, when a balloon ruptures under pressure, the aim is also to provide a balloon that does not cause trauma due to the occurrence of axial rupture. It is well known that it is difficult or necessary to resort to surgical means, and it is an attempt to avoid such a phenomenon.

By selecting a suitable resin, manufacturing an original tube by extrusion molding of the resin, electron beam cross-linking of the original tube, original balloon molding, and heat treatment of the original balloon, a thin wall, flexibility and high pressure resistance are used for an expansion catheter. An object of the present invention is to provide a dilatation catheter having a balloon having a balanced sex.

[0010]

Means for achieving the above object comprises the following constitutions.

(1) An original tube made of a low-density polyolefin resin having a density of 0.93 or less, which is a copolymer of ethylene and α-olefin, is electron beam crosslinked, and the gel fraction of the crosslinked tube is 0.75-0.
The crosslinked tube is 95, and the crosslinked tube is stretched so that the longitudinal draw ratio is at least 130% of the total draw ratio and the effective total draw ratio from the crosslinked tube to the balloon is 5 times or more. To form a raw balloon, which is then preheated to 70 ° C.
A heat-treated balloon having a thermal contraction rate of 20% or less is prepared, and the balloon is expanded with the heat-treated balloon in a substantial expansion region used as the expansion catheter. The ratio is at least 0.20 mm / 6 atm.

(2) The method for producing a dilatation catheter according to (1) above, which is a copolymer of ethylene and α-olefin and has a density of 0.93 or less based on a low density polyolefin resin. Molded into a tube, electron beam cross-linking the tube, to create a cross-linked tube having a gel fraction of the cross-linked tube of 0.75 to 0.95, the cross-linked tube in the total draw ratio, the longitudinal draw ratio is It is at least 130%, and is stretched by blow molding so that the effective total stretching ratio from the crosslinked tube to the balloon is 5 times or more to prepare a raw balloon, and then the raw balloon is heated to 50 to 80 ° C. A heat-treated balloon having a heat shrinkage of 20% or less when subjected to a preliminary heat treatment for giving a heat history and subjected to heat treatment at 70 ° C. for 1 hour,
The heat-treated balloon is attached to the catheter by a predetermined method to obtain a dilatation catheter.

(3) The method for producing the dilatation catheter according to (1) above, which is a copolymer of ethylene and α-olefin and is made of a low density polyolefin resin having a density of 0.93 or less. The original tube was electron beam crosslinked, and the gel fraction of the crosslinked tube was 0.75
A crosslinked tube of 0.95 is prepared, and the crosslinked tube has a longitudinal draw ratio of at least 130% in all draw ratios, and an effective total draw ratio from the crosslinked tube to the balloon is 5 times or more. Is stretched by blow molding to prepare a raw balloon, the raw balloon is attached to a catheter by a predetermined method, and then 50 to 50
Preheated to give a heat history of 80 ℃,
The heat shrinkage rate of the balloon after heat treatment for 20 hours is 20
It is created by subjecting it to heat treatment so that it is not more than%.

Compared with conventionally used polyolefin-based catheter balloons, a balloon made of a copolymer of ethylene and α-olefin has a flexibility and high compliance peculiar to polyolefin by delicately combining various conditions described below. While maintaining sex
It becomes a balloon of higher strength.

[0015]

First, the basic structure of the present invention and terms used in this specification will be described below. The method of manufacturing the balloon used for the dilatation catheter will be described step by step.

In step 1 (S1), ethylene and α-
A low density resin composed of an olefin copolymer (density ≦ 0.93) is molded by extrusion molding or an electric wire coating method,
Create the original tube.

In step 2 (S2), the obtained original tube is irradiated with an electron beam to be crosslinked, and the gel fraction is 0.7.
Make 5 to 0.92 crosslinked tubes.

In step 3 (S3), the obtained crosslinked tube is blow-molded to have a total draw ratio of 5 times or more from the crosslinked tube to the balloon, and a longitudinal draw ratio of at least 130%. To create.

In step 4 (S4), a heat treatment balloon is formed by applying heat history at 50 to 80 ° C. and performing heat treatment. The resulting heat-treated balloon has a heat shrinkage rate of ≦ 25% when reheated at 70 ° C. for 1 hour, and an expansion ratio in a substantial expansion region of ≧ 0.20 mm / 6 atm.

In step 5 (S5), the catheter is attached to the catheter by a predetermined method to prepare a dilatation catheter.

Here, step 4 and step 5 may be interchanged, but step 4 and step 5 are preferable in order to facilitate the procedure of creation.

Next, details of each stage will be described later.

Step 1 (Preparation of original tube) The polymer material used for the balloon used in the dilatation catheter of the present invention is a copolymer of ethylene and α-olefin and has a low density of 0.93 or less. Among polyolefin resins, it is a resin that can be blow-molded as a tubular molded body. JIS K674819
81, polyethylene molding materials are basically classified into 1 to 3 types according to their density, and each type is subdivided into 1 to 6 types according to melt flow rate. The resin used in the present invention has a low specific gravity of less than 0.930. According to this JIS standard, the lower limit of the specific gravity of the first type molding material is 0.910, but 0.9
Those having a specific gravity of less than 10 are also included in the scope of the present invention.

Although various kinds of α-olefins to be copolymerized are known, preferred α-olefins in the present invention are those having 3 or more carbon atoms, preferably 4 or more carbon atoms, and particularly preferably 6 carbon atoms. Is.

Using the polymeric material specified in the present invention having the above properties, the molding of the balloon of the present invention can be carried out by the following steps. First, an original tube (for blow molding) having a predesigned dimension is molded. The tube molding method can be manufactured by an extrusion molding method, a copper wire coating method in which a copper wire is coated with an alloy resin, and then a copper wire serving as an inner core is removed.

In the original tube extrusion molding, cooling of the extruded tube immediately after being discharged from the die is an important requirement for blow moldability, and suitable cooling temperature conditions are set according to the characteristics of the polymer material. Generally, water is used as a cooling medium, but when a lower temperature is required, a cooling medium may be used in place of the cooling water to cool the medium to 0 ° C. or lower.

In the original tube extrusion molding of the present invention, multi-layer extrusion is carried out, or in the copper wire coating method,
By carrying out the multi-layer coating, it is possible to manufacture an original tube having a multi-layer structure. The resin of each layer constituting the multilayer structure can be selected from the group consisting of the same or different polymer materials as the resin of the other layers. In selecting a resin, it is a requirement that the resin of the present invention and the original tube can be formed and blow-molded together. Such a multilayer structure can be utilized to further enhance the effects of the present invention such as improvement of surface characteristics, improvement of releasability during blow molding, and increase of strength.

Step 2 (from the original tube to the crosslinked tube) Irradiation of various polyethylene materials with an electron beam and generation of crosslinked bonds to improve heat resistance are commonly practiced in the electric wire industry and the like. Further, for polyethylene balloons for catheters, this is a method that has already been carried out, but in the present invention as well, a crosslinked tube obtained by irradiating the original balloon obtained above with a specific dose of electron beam is suitable. It was found to exhibit blow moldability.

In general, in the formation of the crosslinked structure by electron beam irradiation, the irradiation atmosphere is involved in addition to the dose. Also,
It is also affected by the shape and size of the irradiated sample. In view of the above, in the present invention, a suitable cross-linking range is defined by the gel fraction used as one of the indexes of the cross-linking degree among experts in the art. In the present invention, the gel fraction of the electron beam crosslinked tube measured by the method described below needs to be 0.75 to 0.95. If it is less than 0.75, the improvement of the stretching characteristics and the burst pressure by electron beam irradiation are insufficient. On the other hand, when it exceeds 0.95, the crosslinked structure becomes too strong,
Flexibility is often compromised. The range of the gel fraction is preferably 0.80 to 0.92, and particularly preferably 0.85 to 0.90. Although it is possible in principle to generate a crosslinked structure by γ-ray irradiation instead of electron beam irradiation, electron beam irradiation, which generally requires a short irradiation time, is preferable.

The method for measuring the gel fraction of the present invention will be described.

The crosslinked tube irradiated with the electron beam is made into pieces, 0.1 to 0.2 g of which is precisely weighed and heated in 100 ml of xylene heated to 120 ° C. for 6 hours. The hot xylene is heated under heating to separate the soluble tube from the crosslinked tube, and the crosslinked tube is dried to a constant weight and precisely weighed to calculate the gel fraction.

Step 3 (Blow molding of crosslinked tube to original balloon) The crosslinked tube prepared through the above steps can be shaped into a balloon by blow pressurization in a constant temperature range. Blow molding using an extruded original tube is described in, for example, JP-B-63-26655. To give an example, insert the above tube into a balloon mold that has a cavity with the desired outer diameter.
Set on the balloon molding machine. Next, the temperature is raised to an appropriate temperature and then stretched in the machine direction. In order to expand and shape the once stretched tube in a blow molding machine, an arbitrary gas, for example, a gas such as nitrogen can be used.
Blow molding using heated gas or the like is also applicable. The above-mentioned longitudinal stretching step and blowing step can be carried out continuously in the same mold, and the temperatures of both steps can be set to the same level. By performing the above-described longitudinal stretching step to blowing step in multiple stages, a high pressure resistant balloon with less uneven thickness can be manufactured.

For a person skilled in the art, the tube is longitudinally stretched as a pre-process for blow-molding the tube. However, if the blow-molding is performed immediately after the tube is stretched, it takes a while. This may be done at a later time.

Further, although the blowing tube can be stretched by using any appropriate stretching apparatus, it is convenient to make sure that the already stretched tube is in an appropriate position when performing the blowing. In the present invention, axial tension may be applied to the crosslinked tube stretched in the blowing step in order to recover the stretched molded product. As explained above, the stretching and expansion steps can be performed at the same or different temperatures. The desired temperature can also be achieved with any suitable heater and water cooling combination.

For the crosslinked tube of the present invention, the preferred longitudinal stretching to blow molding temperature is 30 to 180 ° C., 80
-120 degreeC is more preferable.

If the temperature is lower than 30 ° C., the balloon expansion from the original tube will be poor, and if it exceeds 180 ° C., there will be a problem in that the balloon will be excessively expanded during burst pressure.

Such blow molding is carried out under the following two conditions to manufacture a raw balloon.

The longitudinal draw ratio is at least 130% of the total draw ratio. The effective total draw ratio from the crosslinked tube to the balloon is
The reason for this being 5 times or more is shown below. It is well known in the art that balloon rupture under pressure can cause damage to, for example, the inner wall of a blood vessel due to the axial tear. As previously mentioned, it is known that debris is very difficult to remove in a circumferentially ruptured catheter balloon or requires surgical intervention, and in order to avoid such accidents, the balloon must be extended longitudinally. It is effective to impart a stretch orientation. The longitudinal draw ratio that (potentially) imparts a longitudinal tear as the rupture mode is at least 130%, preferably at least 150%. In addition, the longitudinal stretching ratio is 10 times the original length.
It is a value calculated as 0%.

In the process of forming the original balloon from the crosslinked tube, the burst pressure and the compliance of the obtained balloon can be preferably selected by controlling the stretching orientation in the length and width as effectively as possible. That is, based on the stretching characteristics of the crosslinked balloon, if the stretching ratio is increased as much as possible (within the elongation at break), the strength generally increases, while the compliance gradually decreases.

Therefore, by effectively combining the above-mentioned crosslinking density (expressed by gel fraction) with the longitudinal stretching ratio and the blow stretching ratio during balloon molding, the balloon properties having the excellent properties of the present invention are exhibited. You can

In the present invention, one of the requirements is that the effective total draw ratio from the crosslinked tube to the balloon is 5 times or more. The effective total draw ratio of the present invention is defined by measuring the area ratio. The apparent draw ratio calculated from the moving distance of the balloon molding device does not reflect the actual accurate draw ratio.

Area magnification, calculated according to the following formula: Effective total stretch ratio = (crosslinked tube cross-sectional area) / (balloon cross-sectional area) By achieving such stretch ratio, the balloon of the present invention is flexible and has high compliance. In addition to being sex, the burst strength is also relatively high. The preferred effective total draw ratio is 5 times or more, more preferably 7 times or more, and particularly preferably 8 times or more.

Step 4 (Heat Treatment of Raw Balloon to Heat Treated Balloon) By heat treating the raw balloon obtained above, a heat treated balloon which does not show a large heat shrinkage due to the subsequent heat history can be manufactured. The electron beam cross-linked polyolefin, which is also used as a shrinkable tube, causes shrinkage according to temperature × time when a certain temperature or higher is applied. In the present invention, the heat shrinkage rate of the heat-treated balloon (shrinkage rate for reheat treatment) is as follows: (re) heat shrinkage rate of balloon at 70 ° C. × 1 hour ≦ 25% heat shrinkage rate = (Average thickness of balloon after reheating treatment-average thickness of heat-treated balloon) ÷ (average thickness of heat-treated balloon) In the above equation, the heat shrinkage ratio is the length direction of the balloon (including the taper portion). The contraction rate of. The heat shrinkage rate is preferably 20% or less, more preferably 15% or less, and particularly preferably 10% or less.

The raw balloon of the present invention also tends to cause an increase in the thickness of the balloon, etc. by contracting in the process of assembling into the catheter, for example, the subsequent fusion processing or the final sterilization process. However, according to the method of the present invention, the heat shrinkage rate of the precisely manufactured raw balloon falls within a certain range, so by subjecting the raw balloon obtained by the above-described manufacturing method to heat treatment at a certain temperature x a certain time,
A useful balloon having a small heat shrinkage can be obtained.

The balloon of the present invention is flexible and excellent in compliance. That is, the expansion ratio (compliance) of the balloon diameter is at least 0.20 mm in the substantial expansion region used as the expansion catheter required for the flexible balloon described above.
/ 6 atm. In addition, the substantial expansion area 6 atm is usually 5 to 11 atm, 6 to 12 atm, and 7 to 13 a.
tm, 8-14 atm, etc., and is defined by the reference pressure and burst strength of the balloon. These values can be achieved in the present invention by precisely examining and optimizing the polymer material of the present invention and the degree of crosslinking thereof, as well as the cross-linking tube molding, blow molding, heat treatment method and the like. The preferred compliance is 0.25 mm / 6 atm, a target value referred to as'quarter size cover 'by experts in the art. Particularly preferably, it is 0.30 mm / 6 atm.

The (heat treatment) balloon of the present invention is manufactured by the above-mentioned method, but the heat shrinkage rate of the heat-treated balloon manufactured by subjecting the original balloon to the preliminary heat treatment at 70 ° C. is 20% or less. The heat treatment can be performed with the original balloon as it is, or in a state of being pressurized and expanded with a gas or the like. The treatment temperature can be changed depending on the shrinkage rate required for the balloon, but is usually 50 to 9
The treatment is carried out at 0 ° C. for several hours to several tens of hours, preferably 60 to 80 ° C., and more preferably 65 to 75 ° C.
Is. The preferred treatment time is 2 to 20 hours, more preferably 4 to 10 hours.

In the present invention, the bursting pressure of the obtained balloon must be 12 atm or more. The required burst pressure varies depending on the balloon size, but in any case, at a burst pressure of 12 atm or less,
The effect of the present invention is not sufficiently exhibited, and a highly safe balloon cannot be obtained. The preferred burst pressure is 14 at
It is m or more.

The balloon film thickness of the present invention is 0.010 to
A sufficient and balanced flexibility can be enjoyed between 0.050 mm. As is well known to experts in the field,
The suitable balloon thickness may also vary to some extent with balloon size. If it is less than 0.010 mm, it is flexible but the desired burst pressure cannot be obtained, while 0.0
If it exceeds 50 mm, the flexibility gradually deteriorates. The preferable film thickness is 0.010 to 0.040 mm, and more preferably 0.015 to 0.030 mm.

In the present invention, a catheter containing a balloon is formed by covering a part or all of the outer surface with a hydrophilic (or water-soluble) polymer material at the stage of the crosslinked tube or in the state of the balloon after blow molding. When the outer surface comes into contact with blood or physiological saline, etc., the friction coefficient is reduced and lubricity is imparted, and the slidability is further improved. As a result, pushability, followability, body kink property and safety It is possible to preferably perform a high-order surface treatment that further increases the

As the hydrophilic polymer substance, various natural or synthetic polymer substances or derivatives thereof can be used.

In order to fix such a treatment for improving the slidability to the outer surface of a part or the whole of the catheter including the balloon or the joint portion with the balloon, the reactive functional group present on the balloon surface or intentionally introduced is used. It is preferably carried out by covalent bonding with a group, which makes it possible to obtain a persistent lubricious surface.

The composition of the hydrophilic polymer substance and the coating method in the present invention are described in, for example, JP-A-53-10.
6778, U.S. Pat. No. 4,100,309, JP-A-63
No. 259269 and Japanese Patent Publication No. 1-33181 can be applied.

A specific embodiment of the present invention will be described below in accordance with the steps described above.

[0054]

Example 1 Step 1 (former tube molding) Linear low-density polyethylene (trade name: Nipolon-Z (Z
F130-1), manufactured by Tosoh Corporation, melt flow rate = 1.0 g / 10 min, specific gravity 0.920) was melted by an extruder and coated on a copper wire having a diameter of 0.5 mm. The diameter of the coated electric wire was 0.940 mm. Therefore, the thickness of the (coated) original tube corresponds to 220 μm.

The inner core copper wire was removed from the above alloy-coated copper wire to prepare an original tube.

Step 2 (Preparation of Crosslinked Tube) The above original tube was irradiated with an electron beam of 35 Mrad to be crosslinked to prepare a crosslinked tube.

The gel fraction of the tube at this time was 0.92.

Step 3 (Molding of Original Balloon) The crosslinked tube was placed in a blow molding machine for balloon molding and longitudinally stretched and blow molded at 105 ° C. to prepare a raw balloon.

The effective total draw ratio was 5 or more, and the longitudinal draw ratio of the effective total draw ratio was 160%. Step 4 (Preparation of heat-treated balloon) The original balloon was heat-treated in a heating oven at 70 ° C for 4 hours. The heat treatment caused the balloon to shrink. The heat-treated balloon obtained was flexible and exhibited relatively high pressure resistance (14 to 16 atm).

Step 5 (Assembly of Dilatation Catheter) After thinning the joint of the heat treated balloon and the shaft, the balloon tip side joint is made of a polyolefin inner tube shaft and the base side joint is made of a polyolefin outer tube shaft. They were joined and the hub was joined to the base to build up a good dilatation catheter with a flexible tip.

[0061]

Example 2 As a raw material, linear low-density polyethylene (trade name: Nipolon-Z (ZF260-1), manufactured by Tosoh Corporation, melt flow rate = 2.0 g / 10 mi
A dilatation catheter was produced in the same manner as in Example 1 except that a pellet having a specific gravity of 0.935) was used.

[0062]

The dilatation catheter of the present invention is a copolymer made of ethylene and α-olefin, and the original tube made of a low density polyolefin resin having a density of 0.93 or less is electron beam crosslinked and crosslinked. A crosslinked tube having a gel fraction of 0.75 to 0.95, wherein the crosslinked tube has a longitudinal draw ratio of at least 130% in all draw ratios and an effective total draw from the crosslinked tube to a balloon. A raw balloon is obtained by stretching so as to have a magnification of 5 times or more, and then the raw balloon is subjected to a preliminary heat treatment so that the balloon has a heat shrinkage ratio of 2 at 70 ° C.
A heat treatment balloon having a rate of 0% or less is prepared, and the expansion catheter having the heat treatment balloon has an expansion ratio of the balloon diameter of at least 0.20 mm / in a substantial expansion region used as the expansion catheter. Since it is 6 atm, starting from a flexible polymer material, balloon molding
By carefully controlling the steps leading up to the post-treatment, it is possible to provide a dilatation catheter having a balloon of higher strength while maintaining the flexibility and high compliance inherent in polyolefin.

According to the method for producing a dilatation catheter of the present invention, a low density polyolefin resin, which is a copolymer of ethylene and α-olefin and has a density of 0.93 or less, is molded into the original tube, The tube was electron beam crosslinked, and the gel fraction of the crosslinked tube was 0.7.
A crosslinked tube having a diameter of 5 to 0.95 is prepared, and the crosslinked tube has a longitudinal draw ratio of at least 130% in all draw ratios.
In addition, the raw balloon is drawn by blow molding so that the effective total stretching ratio from the crosslinked tube to the balloon is 5 times or more, and then the raw balloon is
Preheated to give a heat history of 0 to 80 ℃, 70 ℃
The heat-shrinkage rate of the balloon when heat-treated for 1 hour is 20% or less is prepared, and the heat-treated balloon is attached to the catheter by a predetermined method to prepare a dilatation catheter. It is possible to manufacture a dilatation catheter having a balloon of higher strength while maintaining high stability and high compliance.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-205064 (JP, A) JP-A-2-271865 (JP, A) JP-A-59-115349 (JP, A) JP-A-56- 113558 (JP, A) JP 4-292170 (JP, A) JP 2-234766 (JP, A) JP 60-41970 (JP, A) JP 6-7427 (JP, A) JP-A-4-332563 (JP, A) JP-A-60-92765 (JP, A) JP-A-6-23029 (JP, A) JP-A-4-176473 (JP, A) JP-A-3-70575 (JP, A) JP-A-63-192456 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61L 29/00 A61M 25/00

Claims (2)

(57) [Claims] 1. A copolymer of ethylene and α-olefin, which has a density of 0.93 or less and a gel fraction of 0.1.
A balloon obtained by cross-linking and stretching a cross-linked tube made of a low-density polyolefin resin having a density of 75 to 0.95, the balloon having a heat shrinkage ratio at 70 ° C. of 20% or less and having a substantial expansion range. An expansion catheter having a balloon expansion ratio of at least 0.20 mm / 6 atm. 2. The method for manufacturing the dilatation catheter according to claim 1, wherein a low density polyolefin resin having a density of 0.93 or less, which is a copolymer of ethylene and α-olefin, is used as the original tube. After molding, the tube was electron beam crosslinked, and the gel fraction of the crosslinked tube was 0.7.
A crosslinked tube having a diameter of 5 to 0.95 is prepared, and the crosslinked tube has a longitudinal draw ratio of at least 130% in all draw ratios, and an effective total draw ratio from the crosslinked tube to the balloon is 5 times or more. To obtain a raw balloon by stretching by blow molding so that the raw balloon is then subjected to a preliminary heat treatment that gives a heat history of 50 to 80 ° C., and the heat of the balloon when the heat treatment is applied at 70 ° C. for 1 hour. A method for producing a dilatation catheter, characterized in that a heat treatment balloon having a contraction rate of 20% or less is prepared, and the heat treatment balloon is attached to the catheter by a predetermined method to obtain a dilatation catheter.