JPH0691005A - Catheter - Google Patents

Abstract

PURPOSE:To improve insertibility by making the same with the material of a softening portion consisting of a uniform softening part and/or a part whose softenability changes slopewise due to orientation alleviating processing, and with the material of a non-softening portion, discriminating the tensile elasticity rate of the softening portion from that of the non-softening portion at a specific ratio. CONSTITUTION:A mono-layer or multi-layer tube formed in homogeneity is composed of a softening portion consisting of a uniform softening part and/or a part whose softenability changes slopewise due to orientation alleviating processing and a non-softening portion, and the materials of the softening portion and the non-softening portion are made same, and the tensile elasticity rate of the softening portion is discriminated from that of the non-softening portion by more than 5%. This catheter is excellent in insertibility into a body and also excellent in followability in regard to the bending surface of a blood vessel or the like. Also, its manufacture is very simple, and is inexpensive and suited for mass production. Accordingly, an inexpensive and useful catheter is obtained, and the pliability of the softening portion and the non-softening portion can also be controlled extensively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical device catheter and a method for manufacturing the same.

[0002]

2. Description of the Related Art A catheter is a device used for discharging and injecting a body fluid or drug from a body cavity or tubular organ. In recent years, functionalization of catheters has advanced, and for example, a vascular dilatation balloon catheter used for percutaneous angioplasty to dilate a narrowed portion of a blood vessel, a urinary balloon catheter with a temperature sensor capable of simultaneous urination and bladder temperature measurement. , A thermodilution catheter that is placed inside the heart and used for measuring cardiac output, and an intravascular diagnostic catheter for performing intraarterial injection therapy and angiography have been applied. Various applications other than those described above have been attempted for these catheters. It is now being applied to all organs, body cavities and tubular organs.

Up to now, a large-scale operation that requires thoracotomy, craniotomy, and the like has been required for heart and brain surgery, and postoperative recovery rather than surgery itself has been the key to success. With the above-mentioned technique using a high-performance catheter, it is possible to perform diagnosis and treatment with low physical aggression without cutting the human body such as thoracotomy, laparotomy, and craniotomy.

Therefore, there is the following advantage because no major surgery is required. For example, reduction of patient's intraoperative and postoperative pain. Early recovery and early social return after surgery. Less physical damage and less mental burden. Reduction of financial burden. And so on. Therefore, it is expected that diagnostic and therapeutic methods using catheters will continue to develop in the future.

[0005] A catheter for diagnosis and treatment, for example, advances in a blood vessel to reach a target lesion and expands a stenosis,
The purpose is achieved by injecting a drug and measuring the temperature and pressure. Therefore, the basically required function is easy access to the digestive system, circulatory system, respiratory system and organs. Means for reaching the target site include insertion / running into blood vessels, digestive tracts, lymphatic vessels, respiratory tracts, urethra, and other body cavities or tissues. When inserting and running the catheter into the body, it is important that the performance is such that it follows the curved surface (trackability) and that the catheter can be easily pushed in (pushability). In addition, softness that does not damage living tissues is also required. It is considered that the trackability depends on the flexibility of the catheter, and the pusher ability depends on the rigidity of the catheter. That is, it is desired to achieve both the contradictory properties of hardness and softness that influence the good insertability of the catheter.

[0006] In the past, several attempts have been made to improve the tracker and pusher bilities and to improve the catheter insertability.

For example, in US Pat. No. 4,976,690, polyethylene is used as a material, and the diameter is gradually reduced to be different between the base portion and the tip portion of the catheter. This catheter has a smaller tube diameter as it goes to the tip, so the tip side is flexible and has excellent trackability, and the base side has a larger tube diameter, which ensures rigidity and pusherability. However, it has been pointed out that the catheter having a different diameter has a complicated manufacturing method and is apt to be broken at the step portion in practical use. That is, since the tube strength is extremely different at the step portion, stress concentration is likely to occur, resulting in poor kink resistance. The bending strength of a hollow structure is proportional to the product of the moment of inertia of the cross section and the elastic modulus of the material. When the flexibility is controlled by the size of the cross section as in this example, the catheter strength is The stress concentration on the step is inevitable because it changes abruptly. The same is true when tubes with different diameters are connected.

[0008] In US Pat. No. 4,775,371, a high-density polyethylene is used as a material, and the diameter of the catheter is reduced, and a flexible low-density polyethylene is coated on the tip of the catheter. There are things that only the department is made flexible. In this case, there is a problem that a complicated manufacturing process of manufacturing a catheter having a different diameter and coating a resin on the small diameter portion is required, and that the flexible layer covering the small diameter portion is likely to be peeled off due to poor adhesion.

As seen in the above-mentioned two prior arts, the softening of the catheter tip portion improves the trackability.
It has been confirmed that it is effective in ensuring pushability, and although the above problems exist, it has been put to practical use. However, no technology has been proposed so far that achieves softening in an inclined manner.

In addition to the control of flexibility, other measures for improving the insertability include lowering friction resistance and lubricating the outer surface of the catheter. However, the problem of persistence of effect, the problem of not following the curved surface if the material used is hard,
In addition, if the material used is soft, there is a problem such as poor pushability. Therefore, lowering friction resistance and lubrication of the shaft surface are effective for the catheter insertability, but the catheter itself must be insertable. It is considered that the effect can be further doubled by further reducing the frictional resistance and lubrication.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and improves the property necessary for a high-performance diagnostic / therapeutic catheter applied to various body cavities, that is, the insertability. Is aimed at. In particular, it is an object of the present invention to provide a catheter that is highly compatible with the ability to follow a curved surface (hereinafter, referred to as trackability) and the pushability (hereinafter, referred to as pusherability). According to the doctor's opinion, the catheter is ideally a catheter having a tip portion softly inclined and excellent in trackability and a base portion hard and easy to push in and excellent in pushability. In order to achieve this object, it is effective to partially soften the catheter or change the flexibility of the catheter in a tilted manner, and an object of the present invention is to provide a specific manufacturing method thereof and the like.

[0012]

As a result of intensive studies, the present inventors have found that the flexibility of a catheter shaft can be controlled by controlling the molecular orientation when molding a catheter tube. The above object is achieved by the present invention described below.

(1) A homogenously molded single-layer or multi-layer tube, which has a softening portion composed of a portion in which the flexibility changes in a gradient due to orientation relaxation treatment and / or a uniform softening portion, and a non-flexible portion. The softening portion and the non-softening portion are made of the same material, and the tensile elastic moduli of the softening portion and the non-softening portion have a difference of at least 5% or more. Catheter to be.

(2) A polymer material is molded and processed to obtain a hollow molded article having anisotropy, and a part of the molded article is annealed by placing it in a softening temperature atmosphere of the polymer to be used for molecular orientation. A method for producing the catheter according to (1) above, which comprises relaxing and softening.

(3) The method for producing the catheter according to (1) and the catheter according to (2), wherein the raw material resin is a thermoplastic polymer having a melt flow rate (MFR) within a specific range. In this case, the MFR range is preferably 20 or less, and more preferably 0.1 to 10.

In the catheter of the present invention, a thermoplastic resin having a melt flow rate (MFR) in a specific range is used as a raw material, and a highly anisotropic hollow molded product in which molecules are oriented in the axial direction of the tube is extruded / injected. And the like.
In this case, it is better to use a resin whose molecular orientation during molding is less likely to be relaxed, and it is desirable to use a resin having a low MFR. The range of MFR is preferably 20 or less, more preferably 0.1 to 10, and particularly preferably 0.5 to 5 from the viewpoint of easy molding.

In order to soften a part of the molded body, a part of the molded body may be placed in an atmosphere near the softening point temperature of the polymer used to relax the molecular orientation. A softened portion is obtained by the orientation relaxation treatment. The catheter of the present invention obtained by the above simple manufacturing method has a clear difference in flexibility between the softened portion and the non-softened portion that has not been heat-treated,
Moreover, there is basically no difference in size between the softened portion and the non-softened portion. Such a catheter can greatly improve the desired insertability. That is, it is a catheter that achieves trackability and pusherability by orientation and has a graded flexibility at the distal end / base portion, and such a catheter can be provided for the first time by the present invention.

In the present specification, "gradiently changes in flexibility" means that the tensile elastic modulus of the softened portion continuously decreases or increases as it moves from one end to the other end.

The raw material used in the present invention is preferably a polymer material, and a thermoplastic resin is suitable because it is easy to mold. In particular, since the resin used for the catheter is required to have flexibility of the material itself, polyvinyl chloride, polyethylene, polypropylene, polybutene, fluororesin, polyether polyester, polyether polyamide, polyurethane which have been conventionally used as a catheter material. , Polyester, nylon, thermoplastic elastomer and the like are preferable. It is also possible to use a polymer alloy or a polymer blend based on these resins.

It is desirable that the melt viscosity of the resin used as a raw material be high, and that the melt flow rate (MFR) used in film formation be low. The test method of MFR is g / 1 according to the method described in ASTM D1238.
The resin flow rate is 0 minutes. For simplicity, use the catalog value of the purchased resin as a guide. The MFR is preferably low in order to bring out the anisotropy of physical properties, for example, it is preferably 20 or less, and in view of easiness of molding, the range of MFR 0.5 to 5 is particularly preferable.

A hollow molded article is obtained by using a raw material resin by ordinary injection / extrusion molding. In this case, particularly preferable is extrusion molding using a resin having a low MFR because it is simple and recommended. In particular, the point to be noted is that the molding is performed so that the molecular orientation in the uniaxial direction can be obtained, the hot stretching is not smoothly performed, and the cooling is strengthened to fix the molecular orientation. Further, in this case, it is free to form a tube having a single layer, a multilayer, or a plurality of holes.

In order to maintain the shape of the produced tube, the core tube is passed through and the tube is partially softened. The purpose of this is to leave the resin in a temperature atmosphere near the softening point of the resin used and to apply heat to release the motion of the polymer molecular chains to some extent, resulting in the relaxation of the molecular orientation. The degree is controlled by temperature and time. However, it is not preferable to take the temperature and time for the resin to flow.

The device is very simple, and the softening part only needs to be placed in an oven having a constant temperature. The degree of relaxation of orientation can be controlled by temperature and time, and for example, it can be left in a furnace having a temperature gradient for a certain period of time or put in and out of a furnace at a certain temperature at a certain speed. . Further, instead of the furnace, a constant temperature bath using water, glycerin, oil or the like as a heat medium can be used.

The molecular orientation of the catheter referred to in the present invention is evaluated by the tensile elastic modulus and strength / elongation required in the tube tensile test. The measurement method uses a normal tensile tester, the sample tube is fixed between the chucks and pulled at a constant speed,
Record the stress / strain curve and calculate the tensile modulus and strength / elongation. The relaxed and softened portion is different in elastic modulus and strength / elongation property from the non-softened portion, so that the molecular orientation and its relaxation degree can be evaluated.

The catheter of the present invention is characterized in that the difference between the softened portion and the non-softened portion is clear, and there is a numerical difference in tensile elastic modulus of 5% or more. According to the present invention, since it is possible to control the physical properties in an inclined manner, it is not possible to clarify the boundary between the softened portion and the non-softened portion, but it does not mean a measurement error, but it means that the softened portion is certainly softened. It is assumed that there is a difference of 5% or more in the tensile elastic modulus. That is, they are defined as a softening part and a non-softening part with a clear difference of 5% or more. In this case, the tensile elastic modulus of the non-softened portion is used as a denominator and expressed as a percentage. Therefore, the softened portion is defined as a portion having a tensile elastic modulus of 95% or less.

In order to further enhance the effect of the catheter of the present invention, it is free to use a low friction material and lubricate it by surface treatment at the same time, and the effect of the present invention can be enhanced synergistically.

[0027]

EXAMPLES The present invention will be described in detail below with reference to examples. The embodiment is an example of the present invention and is not limited to this.

(Comparative Example 1) As a raw material resin, commercially available polybutene-1 (abbreviated as PB; Mitsui Petrochemical Co., Ltd., trade name Buron, grade P-4000, M)
FR = 1.8) was used. Using this pellet, IKG
Copper wire coating was carried out using an MS20-25 extruder manufactured by Co., Ltd. However, the extrusion molding temperature is 200 ° C.
Normally, the copper wire is not heated, and the copper wire has an outer diameter of 0.86 mm.
I used the one. Carefully pull out the copper wire to an outside diameter of 0.8
After passing through a 4-mm core, it was annealed in an oven at 60 ° C. for 16 hours to remove molding strain. The tube had a thickness of 75 μm, an inner diameter of 0.85 mm and an outer diameter of 1.00 mm. The dimensional error was ± 4% in outer diameter. This tube was subjected to the experiments of the following examples. As a matter of course, the tube was formed homogeneously, and no difference in flexibility was observed.

Example 1 1.5 cm of the core tube containing the core tube prepared in Comparative Example 1 and 21 cm of the tip was held in an oven kept at a temperature of 115 ° C. for 3 minutes. After taking out, it cooled to room temperature and created the catheter tube which has a softening part. The set temperature of 115 ° C is the differential scanning calorimeter (DSC).
It is the starting temperature of the melting point peak of PB measured by the method.

(Example 2) [0030] The core tube containing the core tube having a diameter of 1.5 m prepared in Comparative Example 1 and 21 cm at the tip 21 cm was held in an oven kept at a temperature of 115 ° C for 2 minutes. After taking out, the catheter was cooled to room temperature to prepare a catheter having a softened portion.

(Example 3) 21 cm of the tip of the core tube with a core of 1.5 m prepared in Comparative Example 1 was held in an oven kept at a temperature of 115 ° C for 60 seconds. After taking out, the catheter was cooled to room temperature to prepare a catheter having a softened portion.

(Example 4) The core tube containing the core tube having a diameter of 1.5 m prepared in Comparative Example 1 and 21 cm in the front end was held in an oven maintained at a temperature of 115 ° C for 30 seconds. After taking out, the catheter was cooled to room temperature to prepare a catheter having a softened portion.

Example 5 The tip 21 cm of the core tube with a core of 1.5 m prepared in Comparative Example 1 was held in an oven maintained at a temperature of 115 ° C. for 5 seconds. After taking out, the catheter was cooled to room temperature to prepare a catheter having a softened portion.

(Example 6) The tip 21 cm of the core tube with a core of 1.5 m prepared in Comparative Example 1 was placed in an oven kept at a temperature of 115 ° C for 5 seconds, and then 4 cm / mi.
It was taken out at a pulling rate of n. Upon cooling to room temperature, a catheter with a graded softening section was created. When the softening portion was divided into 7 cm portions and the elastic modulus was measured, different values were obtained. The tip had a lower elastic modulus value.

(Comparative Example 2) The tube 21 containing core having a diameter of 1.5 m prepared in Comparative Example 1 and having 21 cm of tip was held in an oven kept at a temperature of 140 ° C. for 3 minutes. Set temperature of 140
° C is the end temperature of the melting point peak of PB measured by the DSC method. In this case, the resin dripped and a hole was formed in a part of the tube, and a catheter that could withstand practical use could not be obtained. Therefore, it is understood that it is not preferable to perform the relaxation treatment for a long time at a temperature which is much higher than the softening point.

Comparative Example 3 PB of Comparative Example 1 was used as a raw material resin. Using this pellet, M manufactured by IKG Co., Ltd.
Copper wire coating was formed using an S20-25 extruder. However, the extrusion molding temperature was 200 ° C., as is common sense, and in this comparative example, the copper wire was heated to 200 ° C. by high frequency induction heating.
The copper wire used had an outer diameter of 0.86 mm. The copper wire was carefully removed, passed through a core wire having an outer diameter of 0.84 mm, and annealed in an oven at 60 ° C. for 12 hours to remove molding strain. This tube has a wall thickness of 75 μm and an inner diameter of 0.85.
mm × outer diameter 1.00 mm. Dimensional error is ±
It was 4%.

21 cm of the tip of the prepared core tube having a core of 1.5 m was held in an oven kept at a temperature of 115 ° C. for 3 minutes. After taking out, it was cooled to room temperature, but a catheter with a clear softened part could not be made.

(Comparative Example 4) As a raw material resin, commercially available polypropylene (abbreviated as PP; Mitsui Petrochemical Co., Ltd., trade name Hypol, grade F-401, MF)
R = 2.4) was used. Using this pellet, IKG
Copper wire coating was carried out using an MS20-25 extruder manufactured by Co., Ltd. However, the extrusion molding temperature is 220 ° C.
Normally, the copper wire is not heated, and the copper wire has an outer diameter of 0.86 mm.
I used the one. Carefully pull out the copper wire to an outside diameter of 0.8
After passing through a 4-mm core, it was annealed in an oven at 60 ° C. for 16 hours to remove molding strain. The tube had a thickness of 75 μm, an inner diameter of 0.85 mm and an outer diameter of 1.00 mm. The dimensional error was ± 4% in outer diameter. This tube was subjected to the experiments of the following examples.

(Comparative Example 5) A 21 m tip of the core tube with a core of 1.5 m prepared in Comparative Example 4 was held in an oven kept at a temperature of 140 ° C for 3 minutes. Set temperature of 140
C is a temperature lower than the starting temperature of the melting point peak of PP measured by the DSC method. In this case, no softening part was obtained. Rather, the part placed in the oven was harder.

From Comparative Examples 2 and 5, it was found that the treatment temperature was different depending on the resin.

(Example 7) 21 cm of the tip of the core tube with a core of 1.5 m prepared in Comparative Example 3 was held in an oven kept at a temperature of 165 ° C for 3 minutes. Set temperature of 165
C is the onset temperature of the melting point peak of polypropylene measured by the DSC method.

A catheter having a softened portion could be produced even if the resin was different. However, it was found that the treatment temperature differs depending on the resin.

Example 8 As a raw material resin, a commercially available polyether polyamide (abbreviated as PE-PA; ATOC)
HEM, brand name Pebax, grade 2533SA0
0, MFR = 6.0) was used. With this pellet,
Copper wire coating was carried out using an IKG MS20-25 extruder. However, the extrusion molding temperature was 200 ° C. recommended by the resin manufacturer, the copper wire normally heated was not used, and the copper wire used had an outer diameter of 0.86 mm. The copper wire was carefully removed, passed through a core wire having an outer diameter of 0.84 mm, and annealed in an oven at 60 ° C. for 16 hours to remove molding strain.
This tube has a wall thickness of 75 μm and an inner diameter of 0.85 mm.
× The outer diameter was 0.998 mm.

21 cm of the tip of the prepared core tube having a core of 1.5 m was held in an oven kept at a temperature of 135 ° C. for 3 minutes. The set temperature of 135 ° C. is the starting temperature of the melting point peak of this grade PE-PA measured by the DSC method.

A catheter having a softened portion could be produced even if the resin was different. However, it was found that the treatment temperature differs depending on the resin.

Example 9 As a raw material resin, a commercially available polyether polyester (abbreviated as PE-PT); Toray
DuPont, Trade name Hytrel, Grade 4797
B, MFR = 2.0) was used. With this pellet,
Copper wire coating was carried out using an IKG MS20-25 extruder. However, the extrusion molding temperature was 220 ° C. recommended by the resin manufacturer, and the copper wire normally used was not heated, and the copper wire used had an outer diameter of 0.86 mm. The copper wire was carefully removed, passed through a core wire having an outer diameter of 0.84 mm, and annealed in an oven at 60 ° C. for 16 hours to remove molding strain.
This tube has a wall thickness of 75 μm and an inner diameter of 0.85 mm.
× The outer diameter was 1.003 mm.

21 cm of the tip of the prepared core tube having a core of 1.5 m was held in an oven kept at a temperature of 180 ° C. for 3 minutes. The set temperature of 180 ° C. is the onset temperature of the melting point peak of this grade PE-PT measured by the DSC method.

A catheter having a softened portion could be produced even if the resin was different. However, it was found that the treatment temperature differs depending on the resin.

Test Example 1 Softening by Relaxation of Molecular Orientation The dimensions of the softened and non- softened parts of Examples 1 to 5 and Comparative Examples 1 and 3 described above and the tensile test in the tube axial direction were carried out to obtain the tensile strength. The elastic modulus was measured. The results are summarized in Table 1.

[0050]

[Table 1]

From Table 1, in the PB tube of Example 1, a clear difference in tensile elastic modulus was observed between the softened portion and the non-softened portion. It was also confirmed from the results of Examples 1 to 5 that the tensile elastic modulus was different depending on the treatment time. This experimental fact suggests that the flexibility can be controlled by relaxing the orientation. Therefore, it is suggested that the flexibility can be changed in an inclined manner at the pulling rate as in Example 6.

Test Example 2 Inclined Softening Table 2 shows the results of a tensile test in which the orientation relaxation portion of Example 6 was divided into 7 cm portions from the tip.

[0053]

[Table 2]

It can be seen that the tube of Example 6 has a lower tensile elastic modulus toward the tip. Therefore, it is considered to be a tube whose elastic modulus changes in an inclined manner. That is,
It can be said that a cartel with a gradually changing flexibility has been realized. As a method of changing the flexibility in an inclined manner, it is also possible to put it in a furnace with a temperature gradient for a certain period of time to relax the orientation.

(Test Example 3) Orientation Relaxation Conditions In Comparative Example 2, the temperature and time conditions for the relaxation treatment were made extreme. Under the condition that the resin flows down, holes were formed or deformed, and a sample worthy of evaluation could not be obtained. Therefore, it is considered preferable to relax the orientation near the softening point temperature.

Comparative Example 3 is the result when the copper wire was heated, the hot drawing was smoothly performed, and the copper wire was molded by the molding method in which the orientation was not left. Heretofore, attention has been paid to how to mold without leaving the molecular orientation, and heating of a copper wire is a well-known technique widely used for that purpose. Therefore, in order to realize the present invention, it is desirable to mold so as to positively leave the molecular orientation.

Comparative Example 5 is an example in which the treatment is performed at a temperature not higher than the softening point temperature. In this case, the orientation was not relaxed and the softened portion was not obtained.

In Examples 7, 8 and 9, it was shown that even resins other than PB can be softened by relaxing the orientation. It is a well-known fact that the physical properties of a thermoplastic polymer having a low melt flow rate (MFR) are basically anisotropic.
The issue is how to eliminate the orientation. Therefore, it is considered that the present invention utilizing orientation relaxation can be carried out with many resins. However, since the PE-PA used in Example 8 has a higher MFR as compared with the resins of the other Examples, it is difficult to be oriented, and therefore the softening rate by the orientation relaxation treatment is low. Therefore, it is considered that if the MFR is low, the one having a lower MFR is more likely to be molecularly oriented, and hence the flexibility is more easily controlled by the orientation relaxation.

Table 3 summarizes the results of the dimension measurement of the softened portions and non-softened portions of Examples 7 to 9 and Comparative Examples 2, 4, and 5, the tensile test in the tube axial direction, and the tensile elastic modulus. .

[0060]

[Table 3]

The present invention has been specifically shown by the examples and comparative examples. It will be apparent that the present invention provides a catheter with a tip that is softened in an inclined manner. As a result of a test in which a tube with a softened tip was actually installed in a vasodilator catheter, the insertability was improved. The catheter has excellent trackability and pushability.

[0062]

Industrial Applicability The catheter of the present invention is excellent in the ability to be inserted into the body, and is also excellent in following the curved surface such as a blood vessel. Moreover, the manufacturing method of the present invention is very simple and inexpensive, and is suitable for mass production. Therefore, a cheap and useful catheter can be obtained, and the flexibility of the softened portion and the non-softened portion can be widely controlled.

From the above, it is possible to improve the insertability, the followability and the flexibility by making the tip end softer than the conventional catheter. That is, the ease of inserting the catheter is obtained, and it is easy to add functions such as reducing the pain of the patient and preventing damage to the living tissue.

From the above, the catheter of the present invention can greatly contribute to the diagnosis and treatment using the catheter, which is currently advancing rapidly.

Claims (1)

[Claims] 1. A homogenously molded single-layer or multi-layer tube, comprising a softening portion comprising a portion where the flexibility changes in a gradient due to orientation relaxation treatment and / or a uniform softening portion, and a non-softening portion. Characterized in that the softening portion and the non-softening portion are made of the same material, and the tensile elastic moduli of the softening portion and the non-softening portion have a difference of at least 5% or more. catheter.