JP2001293082A - Medical catheter containing inorganic crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catheter shaft made of a polyimide in which elongation is improved without impairing the modulus of elasticity. SOLUTION: A medical catheter is made of an inorganic crystalline composite material in which an inorganic crystal is contained in the polyimide. The catheter is excellent in pushability and trachability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a medical catheter such as a catheter or a balloon catheter having a balloon.

[0002]

2. Description of the Related Art Balloon catheters equipped with balloons are becoming more and more useful in medical treatment and are being actively improved to improve their functions. As a treatment method using a balloon catheter, percutaneous coronary angioplasty (PTCA) for expanding a stenotic part of a blood vessel such as a coronary artery, percutaneous angioplasty (PTA) for expanding a stenotic part such as a peripheral blood vessel, Aortic balloon pumping (IABP).

[0003] Balloon catheters in PTCA and PTA are required to have a function of tracking (trackability) and force transmission (pushability) for the purpose of inserting a balloon portion into a stenosis of a peripheral blood vessel. In particular, the shaft part, which is a main component of the catheter, is made thinner (thinner) while ensuring pressure resistance, kink resistance, and dimensional stability for the purpose of improving trackability and pushability, and A function having flexibility is required.

[0004] Since polyimide has a high elasticity and can produce a shaft having excellent pushability, a catheter using polyimide for the shaft portion of a catheter has recently been sold. However, while having a high modulus of elasticity, it is a material having poor flexibility and poor trackability.

[0005]

The shaft made of polyimide of the prior art is excellent in pushability due to its high modulus of elasticity, and is thin because of its excellent pressure resistance and dimensional stability. Although it is a material that can also be made smaller in diameter, it is inferior in trackability due to its low flexibility and especially low elongation.

Although the elongation of polyimide can be improved by the reaction method, starting materials, and curing conditions,
Elongation and elastic modulus are in inverse proportion, and there is a potential problem that pressure resistance and dimensional stability are reduced when elongation is improved. Has not yet gotten.

[0007]

The problems associated with such a shaft portion are solved by the medical catheter according to the present invention, which is made of an inorganic crystal composite material containing inorganic crystals in polyimide.

More specifically, the effect of the present invention is more easily exhibited when the inorganic crystal is a layered crystal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION First, inorganic crystals used in the present invention are shown in Table 1 by classifying them by composition. Of the inorganic crystals, Table 2 shows layered crystals having a layered structure, Table 3 shows ion-exchangeable layered crystals containing ions between layers, and Table 4 shows other layered crystals forming interlayer compounds. A representative inorganic crystal is shown as an example.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4] Although there are various shapes and sizes of inorganic crystals, the effect of the present invention is exhibited by using an inorganic crystal composite material containing an inorganic crystal shown in Tables 2, 3 and 4 for a shaft portion. It is easy to do and is preferable.

In particular, an inorganic crystal composite material obtained by ion-exchange (organization) of a layered crystal by intercalation, for example, an inorganic crystal composite material using organic montmorillonite, has an inorganic crystal of 0.5%. It can be monodispersed in the nano order from nanometers to 100 nanometers. For the same content, the nanodispersion increases the total surface area of the inorganic crystal and reduces the distance between the particles. Interaction due to ionic bonding or the like is further increased, and mechanical strength is improved. Therefore, an ion-exchange layered crystal in which the intercalation can be easily performed and the inorganic crystal can be monodispersed is preferable as the inorganic crystal used in the present invention. Is a more preferable material.

The upper limit of the inorganic crystal content of the inorganic crystal composite material varies depending on the starting materials, the reaction conditions, and the combination of the inorganic crystals to be contained. However, the upper limit is generally 30%. You can't do more than that.

Similarly, the lower limit of the content of the inorganic crystal in the inorganic crystal composite material varies depending on the starting materials, the reaction conditions, and the combination of the inorganic crystal to be contained, and is difficult to limit. It is difficult to improve mechanical strength and obtain directivity.

The method for synthesizing the polyimide-inorganic crystal composite material includes a method for synthesizing a polyimide via a polyamic acid from tetracarboxylic dianhydride and a diamine, wherein a polyamic acid as a precursor thereof is mixed with an inorganic crystal. For example, bis (4-aminophenyl) ether (O
DA) and pyromellitic anhydride (PMDA) to form a polyamic acid, followed by mixing inorganic crystals, adding acetic anhydride and pyridine, and performing a dehydration cyclization reaction.

In addition, as a method for synthesizing polyimide, N
-A synthesis method using a silylated diamine, a synthesis method via a polyamic acid ester and a synthesis method from a tetracarboxylic acid or a tetracarboxylic diester and a diamine,
There is a synthesis method via polyisoimide, a synthesis method from tetracarboxylic dianhydride and diisocyanate, a synthesis method from tetracarboxylic dithioanhydride and zoamine, and a synthesis method for polyetherimide by aromatic nucleophilic substitution polymerization. There is a method of mixing inorganic crystals in the course of these synthesis.

In addition to the method of mixing the inorganic crystal with the polyamic acid as the polyimide precursor, the inorganic crystal composite material can be obtained by, for example, dispersing the inorganic crystal in ODA and synthesizing the same.

As a method for facilitating the dispersibility of the inorganic crystal, a method of subjecting the interface of the inorganic crystal to a surface treatment with a silane coupling agent, an interlayer insertion method (intercalation), and taking out atoms and molecules from the interlayer are provided. A method (deintercalation), for example, a polymerization method or a polymer insertion method after monomer insertion, or an electrode oxidation reaction may be selected and used. In particular, in the case of an ion-exchange layered crystal,
When the intercalation is used, the inorganic crystal is monodispersed and a dispersion of the order of nanometers is obtained, and a favorable inorganic crystal composite material is obtained.

In the intercalation, the ion exchange capacity of the ion exchangeable layered crystal is 20 meq / l.
A thing of 00 g or more is preferable. Below this, it becomes difficult to incorporate organic molecules between layers. For example, smectite is 60-120 meq / 100 g and vermiculite is 100-165 meq / 100 g. These are ion-exchanged (organized) with ionized ammonium ions only by contact with an aqueous solution of n-alkylamine hydrochloride to facilitate the incorporation of organic molecules.

In addition, for inorganic crystals having a high charge density and a strong bonding force between layers, for example, muscovite having a charge density of 1.0 is reacted with a barium chloride solution at 120 ° C. to exchange ions. For example, the pretreatment may be selected according to the characteristics and properties of each layered crystal, and organic treatment may be performed.

Even in the case of a layered crystal which is not ion-exchangeable,
For example, a method suitable for each layered crystal is selected, such as a method of reacting n-butyllithium in a hexane solution or a method of simultaneously performing reduction in a crystal layer and intercalation of alkali ions using a strong reducing agent. And then make it organic.

In the present invention, it is possible to achieve an extension of the conventional technique by forming a shaft using an inorganic crystal composite material obtained by synthesizing various inorganic crystals and various starting materials by a mixing method suitable for them. It has been found that a shaft having improved elongation characteristics while suppressing a decrease in elastic modulus that has not been obtained can be obtained.

Further, in the case of an inorganic crystal composite material using a layered crystal as an inorganic crystal, when a shaft is formed from polyamic acid by a dipping method, a phenomenon that the plane portions of the layered crystal are uniformly arranged as shown in FIG. 3 is used. By arranging the layered crystals in the shaft, it is possible to form a shaft having directivity in strength in a specific direction.

[0026]

EXAMPLES (Example 1) N-silylated diamine 1.73
g of 12.5 ml of N, N-dimethylaceamide (DM
Ac) was dissolved in Ac), and 1.09 g of PMDA was added at 5 ° C., followed by stirring at 20 ° C. for 1 hour and at 50 ° C. for 12 hours under a nitrogen stream to synthesize a polyamic acid. To this polymerization solution, 0.14 g of montmorillonite intercalated with alkylammonium ions was added and sufficiently dispersed.

A polyamic acid (varnish) in which the organized montmorillonite was dispersed was cast on a glass plate to form a film. The cast film was left at room temperature for 1 day, 60 ° C. for 12 hours, 100 ° C. for 12 hours, 150 ° C. for 6 hours,
Dry under reduced pressure at 00 ° C for 6 hours and then at 300 ° C under a nitrogen stream.
For 2 hours to obtain a film composed of a polyimide-based inorganic crystal composite material.

Similarly, films made of a polyimide-based inorganic crystal composite material having different elastic moduli in which organic montmorillonite was dispersed in polyamic acid were prepared. Further, as a comparative example, a film was prepared by using the same composition and raw materials, but without adding the organized montmorillonite. The mechanical properties of the films were measured for tensile strength and elongation according to the tensile test method for plastic films and sheets (JIS K7127). The results are shown in FIG. 1, and it was found that the polyimide to which the organized montmorillonite was added had high elastic modulus and high elongation.

(Example 2) After immersing a copper tube having an outer diameter of 0.6 mm in the varnish prepared in Example 1, the outer periphery of the copper tube is coated with varnish while slowly lifting (dipping). The dipped copper tube was passed through a donut-shaped metal fitting (sizing) to adjust the outer diameter to 0.7 mm (the above forming method is called a dipping method). When the outer diameter was formed by sizing, the sizing was performed at a rotation speed of 1 rpm and a shaft pulling speed was controlled at 7 mm / min so as to have a right spiral of 45 ° with respect to the axial direction.
Then at room temperature for 1 day, 60 ° C for 12 hours, 100 ° C for 1 hour.
The resultant was dried under reduced pressure at 150 ° C. for 6 hours and at 200 ° C. for 6 hours, and then heated at 300 ° C. for 2 hours under a nitrogen stream.

After the copper tube as a core material is completely dissolved with sulfuric acid of 90 wt% or more, the tube is thoroughly washed with water and dried, and is made of a polyimide inorganic crystal composite material having an inner diameter of 0.6 mm and an outer diameter of 0.7 mm. Got the shaft. Further, as a comparative example, a shaft containing no inorganic crystal was prepared. Each shaft is connected to a simulated blood vessel 2 (inner diameter 1 m) of a simulated blood vessel model 1 shown in FIG.
m), when the shaft is pushed in, whether the pushing force on the hand side is sufficiently transmitted to the shaft tip side against the resistance due to the friction of the contact part with the simulated blood vessel model (pushability), (R0.5mm, 90 ° bending)
On the other hand, whether or not the shaft followed and bent (trackability) was visually observed by repeatedly inserting and removing the shaft. As a result, in the case of a shaft containing no organized montmorillonite, the shaft was completely bent at the S-shaped loop portion 3 so that insertion was impossible, but the shaft made of the polyimide-inorganic crystal composite material had no problem with the S-shaped loop portion 3. It was found that the material had excellent pushability and trackability after passing.

A sensor (torque gauge) for detecting a stress in the torsion direction was attached to the tip end side of the shaft in Example 2, and a turntable was attached to the hand side. Turntable 18
By rotating the shaft by 0 degrees and applying a torsional force to the shaft and measuring the torsional stress of the torque gauge on the tip side, the torque transmitted to the tip for both clockwise and counterclockwise rotations is the same at 30 gf for a shaft that does not contain organized montmorillonite. There was,
The shaft made of the polyimide-inorganic crystal composite material has a high torsional stress in the torque transmitted to the tip of 40 gf in the clockwise rotation and 80 gf in the counterclockwise rotation with respect to the torque, and there is a difference in the amount of torque transmitted from the hand side to the tip side (specific direction). Has a directivity in intensity with respect to).

[0032]

According to the present invention, the elongation characteristic is improved by suppressing the decrease in the elastic modulus which cannot be achieved by extending the conventional technology by forming the shaft using the polyamide-based inorganic crystal composite material. You can get a shaft. That is, a shaft having excellent pushability and trackability can be obtained.

Further, in the case of an inorganic crystal composite material using a layered crystal as the inorganic crystal, the shaft can have directivity by arranging the layered crystal in the process of forming the shaft from polyimide acid.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between elongation and elastic modulus of various polyimides of Example 1.

FIG. 2 is a diagram showing a pseudo blood vessel model.

FIG. 3 is a diagram illustrating a state in which plane portions of a layered crystal are oriented.

[Explanation of symbols]

 Reference Signs List 1 simulated blood vessel model 2 simulated blood vessel 3 S-shaped loop

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 79/08 C08L 79/08 Z (72) Inventor Noriyuki Suzuki 5-5-32 Torikai Nishi, Settsu-shi, Osaka −504 F term (reference) 4C081 AC08 BB07 BC02 CA231 CF132 CF142 CF152 CF162 CF21 CF22 CF24 CF26 DA03 DC13 EA06 4J002 CM041 DJ006 FD016 GB01

Claims (8)

[Claims] 1. A medical catheter comprising an inorganic crystal composite material containing an inorganic crystal in polyimide. 2. The medical catheter according to claim 1, wherein the content of the inorganic crystal is 5% or more and 30% or less. 3. The medical catheter according to claim 1, wherein the inorganic crystal is a layered crystal. 4. The medical catheter according to claim 1, wherein the inorganic crystal is an ion-exchange layered crystal. 5. The medical catheter according to claim 3, wherein the layered crystal is smectite or vermiculite. 6. The medical catheter according to claim 4, wherein the ion-exchange layered crystal is a silicate. 7. The medical catheter according to claim 4, wherein the ion-exchange layered crystal is montmorillonite. 8. The medical catheter according to claim 1, wherein the medical catheter is a balloon catheter having a balloon.
8. The medical catheter according to claim 7.