JPH06134886A - Branch tube and production thereof - Google Patents

Abstract

PURPOSE:To obtain a branch tube having a smooth surface free from a joint or a connection part by forming a long member having a shape wherein a plurality of tubes are preliminarily integrated and cutting the tube walls of both ends of the long member to form a branch structure. CONSTITUTION:A tetrafluoroethylene resin porous tube having an 8-shaped cross section is formed. This long object has two tube holes 4 around its center line. Next, when the wall between the tube holes 4 is cut along the line connecting the centers of the tube holes 4 of the tube having the 8-shaped cross section, a tube 13 having one large tube hole wherein two tube holes 4 are connected. In this case, when a part not cutting the tube wall is left at the central part of the long object, a tube wherein two small caliber tubes 2 are branched from a large caliber tube 1 can be obtained. By this constitution, the branch tube having smooth surface free from a joint or connection part can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube having a branched structure and a method for manufacturing the tube.

[0002]

2. Description of the Related Art Tubes are mainly used for transporting fluids such as liquids and gases, separation membranes, and coatings for linear structures. As the material for forming the tube, metal,
There are ceramics and synthetic polymers. For example, a tetrafluoroethylene resin porous body tube obtained by the stretching method is
It is used in a wide range of fields such as filamentous separation membranes and artificial blood vessels.

By the way, in the liquid sending tube, the liquid may be distributed in a large number. Even in the artificial blood vessel, it may be required to connect one blood vessel to a plurality of blood vessels. The linear structure to be covered with the tube may have a plurality of branches. A tube having a branched structure (branch tube) is required for such an application, but there has been no effective means for manufacturing the branched tube in the past.

Generally, as a method for manufacturing a tube, the material forming the tube is (1) poured into a hollow mold before being melted by heat or cured as a solid, and (2) a core pin and a die are arranged. A typical method is extrusion molding into a tube. The method using the hollow mold is complicated, and in order to manufacture the tube at low cost,
The extrusion method is advantageous. However, it is impossible to form a tube having a branched structure by the extrusion molding method.

A method of connecting a plurality of extruded tubes is conceivable for producing a branched tube. That is, it is a method of forming a branch by connecting a plurality of other tubes obtained by extrusion molding to one tube obtained by extrusion molding. However, this method
The process is complicated and usually requires special means to secure the strength of the connection portion. Further, when a non-porous tube is targeted, it is possible to form a branched tube by this connection method, but a porous tube such as a separation membrane tube, particularly a stretched porous tube is targeted. And if that is not practical. In the method of connecting a tube having a single tube hole, in the case of a porous body tube, the connection part becomes non-porous, and the original characteristics of the porous body are impaired. Furthermore, when internal pressure is applied, such as in a separation membrane, in order to secure the breaking strength of the connection part, for example, strict reinforcement such as wrapping with a reinforcing tape is required, and this reinforcement causes traffic on the inner and outer surfaces of the porous tube. Sex will be impaired.

[0006] Specifically, for example, in the case of a separation membrane tube, the flow rate of the filtrate decreases due to the connection.
Further, the connecting portion is likely to form a step on the inner surface of the tube hole, which may cause accumulation or accumulation of the filtered material. In the case of catheters and artificial blood vessels, this step may cause blood accumulation, and the non-porous nature of the connection also impedes the invasion of tissue into the porous body and delays healing. Become.

As another method of making a branch tube,
A method of pouring the molding material into a hollow mold having a branched structure is conceivable, but the process is still complicated. Moreover, in the case of a stretched porous body tube, it is necessary to stretch the obtained branch tube, but it is extremely difficult to branch and uniformly stretch a tube having a deformed shape in the longitudinal direction, It is difficult to obtain a stretched and branched tube having a simple structure.

As described above, according to the prior art, the manufacture of the branch tube becomes very complicated, and in particular, it is practically impossible to manufacture a branch tube that can be practically used with the expanded porous tube. there were.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a branch tube by a relatively simple method. Another object of the present invention is to provide a branch tube having an inner surface that is smooth and has no joints or joints like the conventional straight tube having a single tube hole.

As a result of intensive studies to overcome the above-mentioned problems of the prior art, the present inventor formed an elongated body having a shape in which a plurality of tube holes are arranged around a center line in the longitudinal direction, At one end of the elongated body, a wall between the tube holes is cut so as to divide each tube hole to form a plurality of branch pipes, and at the other end,
It has been found that a branch tube having no connection portion can be obtained by cutting the wall between the tube holes so as to connect the plurality of tube holes to form a tube hole having a large hole diameter. According to this method, the molding material can be extruded into a tubular shape and then stretched. That is, the branched structure can be formed after the stretched porous body tube having a plurality of tube holes is prepared.

Further, a plurality of elongated bodies having a single tube hole are bundled, and at one end, the tube walls of each elongated body are bonded and integrated, and then the plurality of tube holes are connected to one another. A branch tube can be obtained by a simpler method by cutting the wall between the tube holes to form a tube hole having a large hole diameter. The present invention has been completed based on these findings.

[0012]

Thus, according to the present invention, there is provided an elongated body having a shape in which a plurality of tube holes are arranged around a center line in the longitudinal direction, and at one end of the elongated body. , A plurality of branch pipes formed by cutting the wall between the pipe holes so as to divide each pipe hole, and at the other end, a wall between the pipe holes so as to connect the plurality of pipe holes to one There is provided a branch tube having a large-diameter tube hole formed by cutting the.

Further, according to the present invention, (1) an elongated body having a shape in which a plurality of tube holes are arranged around a center line in the longitudinal direction is formed, and then (2) the elongated body is formed. At one end, the wall between the tube holes is cut so as to divide each tube hole to form a plurality of branch pipes. (3) At the other end, the tube holes are connected so as to connect the plurality of tube holes into one. There is provided a method for manufacturing a branch tube, which comprises cutting a wall of a tube to form a tube hole having a large hole diameter.

Further, according to the present invention, a plurality of elongated bodies having a single tube hole in the longitudinal direction are bundled, and at one end thereof, the tube walls of the elongated bodies are integrated by adhesion, A method for manufacturing a branched tube is provided, in which a wall between the tube holes is cut so as to connect the plurality of tube holes to each other to form a tube hole having a large hole diameter.

The present invention will be described in detail below. In the first method of the present invention, rather than connecting a plurality of tubes to one tube to obtain a branched structure, a long body having a shape in which a plurality of tubes are integrated is formed in advance, and The tube wall is cut to form a branched structure. That is, a long body having a plurality of pipe holes in the long axis direction is formed, and the wall between the pipe holes is cut so that one end of this long body is connected to the pipe hole to form a portion having one large pipe hole. Molding is performed, and the other end is cut in a direction that divides the wall between the tube holes to branch into a plurality of tubes having one tube hole.

The tube thus obtained has a structure in which one large tube hole is branched into a plurality of tube holes, and a branched tube can be obtained without connection. The manufacturing method of the present invention is not only easier than the above-described connection method and the method of pouring into a hollow mold, but also has no problems such as reinforcement at the connection portion and obstruction of traffic.

In the second method of the present invention, among these advantages, simplicity is further pursued, and the step of extruding a long body having a plurality of tube holes is omitted, and a straight tube having a single tube hole is provided in advance. A large hole diameter is obtained by bundling a plurality of tubular tubes and adhering and integrating the tube walls at one end of the bundle by melting, etc., and then cutting the wall between the tube holes so as to connect the plurality of tube holes into one. To form a tube hole. That is, among the first methods of the present invention, only the method of forming a large-diameter tube hole is adopted.

In the case of a stretched porous tube made of a synthetic resin such as polypropylene, polyethylene or tetrafluoroethylene resin (hereinafter abbreviated as PTFE), the first method of the present invention has a simple manufacturing process, In addition, a branched tube having excellent physical properties as a porous body can be obtained, which is particularly preferable.

As a specific example of the branch tube, an artificial blood vessel made of a PTFE porous tube produced by a stretching method will be described below. The tetrafluoroethylene resin porous body tube (hereinafter abbreviated as EPTFE tube) obtained by the stretching method is a porous body having a fine fibrous structure composed of fibers and knots connected to each other by the fibers. This porous structure is made up of PTFE bonded by paste extrusion.
Part of the powder is dissociated by stretching to form pores, part of which remains bonded and becomes fibrous, and the PTFE powder is melted and bonded to form a nodule by heat applied at the same time or later. It

For this reason, the fine fibrous structure largely depends on the heating amount and the stretching rate in the stretching step and the sintering step. Industrially, the stretching process is performed by an apparatus in which a heating furnace is arranged between two rotating drums. The extruded tube wound around one rotating drum (supply drum) is supplied to the heating furnace at a constant speed, and then wound around the other rotating drum (winding drum) at a constant speed. At this time, the tube is stretched by making the rotation speed of the winding drum higher than the rotation speed of the supply drum, and this ratio is the stretching ratio. Industrially, an EPTFE tube having a uniform fine fibrous structure can be obtained by controlling and controlling the rotational speeds of the two drums, the furnace temperature and the like in this step. Sintering is performed at the same time as the stretching or after the stretching step.

As described above, the EPTFE tube is generally manufactured as a long body (continuously molded body), and it is difficult to stretch it uniformly and apply heat to it by batch processing. In addition, there is a problem in cost. However, the branched EP which is the object of the present invention
Since the TFE tube has a branch, it has no continuity,
It cannot be manufactured as a long body by the above method.

The first method of the present invention will be described by taking as an example the case of manufacturing an EPTFE branch tube having two branches. First, according to the EPTFE manufacturing process described above, as shown in FIG. 2, an EPTFE tube having an 8-shaped cross section, in which two tubes are stuck together, is prepared. This elongated body has two tube holes (4, 4) around its center line. In this case, the center line of the elongated body is a line obtained by extending the intersection point of the line (6) connecting the centers of the two tube holes and the midline (7) between the two tube holes in the long axis direction. Is.

To make a long body having such a shape,
In the paste extrusion process, a die having the same shape as the outer wall of the tube shown in FIG.
The core pins (8, 8) of the book are arranged as shown in FIG. 3, and the tube is extruded to form a tube having a cross-section 8 shape, and then the stretching step and the sintering step are performed simultaneously or sequentially. Therefore, the EPTFE as shown in FIG.
A baked product can be obtained.

Next, as shown in FIG. 4, in the tube having the V-shaped section, the wall between the tube holes is cut by a line (14) connecting the centers of the tube holes to connect the two tube holes. Resulting in a tube (13) with one large bore. On the other hand, FIG.
As shown in Fig. 2, cutting the wall between the tube holes so as to divide each tube hole at the median line (17) of each tube hole separates the tube into two tubes (16, 16) having one tube hole. To do. If a portion where the tube wall is not cut is left in the central portion of the elongated body, a tube that branches from a tube with a large diameter into two tubes with a small diameter can be obtained, as shown in FIG.

In order to adjust the cut surface and diameter, a Y-shaped metal rod having a branched shape formed into a desired shape and diameter is inserted into a tube tube hole and heated to a melting point of EPTFE of about 327 ° C. or more, The inner surface of the branch tube can be shaped along the metal rod shape. At this time, the inner surface of the portion of the tube having a large diameter, which was shaped like a peanut only by cutting the tube wall, becomes a clean circular inner surface. As described above, a branched artificial blood vessel having a smooth inner surface without a connecting portion can be obtained.

The EPTFE tube having an 8-shaped cross section, which is the base material of the present invention, has a wall between the inner surfaces of the two tube holes and an outer wall through which the midline of the two tube holes passes by the subsequent cutting operation. Since the wall in between is divided into two tube walls, it is desirable that both wall thicknesses are about twice the tube wall thickness in the peripheral portion. Further, in order for the wall shapes after the two types of cutting operations to be smoothly continuous, it is desirable that the outer wall be formed of a smooth curve as shown in FIG. That is, it is desirable that the outer surface portion of the elongated body through which the midline between the plurality of tube holes passes is constricted toward the center line of the elongated body in the long axis direction.

In the case of an artificial blood vessel, there is almost no case where three or more branches are required, but in the liquid-feeding tube, the liquid is often distributed in many cases. When producing a tube having a large number of branches used for such an application, for example, a long body having three tube holes as shown in FIG. 6 or a long body having four tube holes as shown in FIG. It is necessary to create an elongated body having three or more tube holes, such as a scale. In such a long body, it is necessary to form a plurality of tube holes around the center line in the long axis direction in order to form a tube hole having a large hole diameter.

In the present invention, also in the case of using an elongated body having three or more tube holes, one end connects the center of this elongated body and the center of the tube hole as in the case of two tube holes. It is possible to obtain a multi-branched tube by cutting with a line to form a plurality of branch pipes and cutting the pipe wall at the other end so as to separate each pipe hole.

Also in this case, as in the case of two tube holes,
As shown in FIGS. 6 and 7, the outer surface of the long body to be used has a constricted shape toward the center line in the long axis direction of the long body so that the tube shape after branching is smooth. Becomes

The cross-sectional shape of the elongated tube hole does not have to be circular, and may be elliptical or the like as shown in FIG. In particular, in the case of branching a large number of four or more tube holes, it becomes difficult to form a clean concentric circle on the inner surface and the outer surface when divided into a branched shape. In such a case, as shown in FIG. 7, the tube hole is formed into an ellipse, or a hole (20) for branching is provided at the center line of the long body in the long axis direction, so that the inner and outer surface shapes after the division are changed. It can be close to concentric circles.

The extrusion die for forming the elongated body used in the present invention has a shape similar to that of the outer wall of the elongated body which is constricted toward the center line in the longitudinal direction, that is, in the case of a figure eight shape. Then, as shown in FIG. 3, two circular holes (9) contacting each other are formed on the inner surface of the die, and the core pin diameter (11) to be inserted is subtracted from the diameter of the circular hole to obtain a width (10). It is necessary to connect two circular holes and chamfer the edges. The shape formed by this curved surface is E generated during the EPTFE manufacturing process or due to mechanical load on the product.
It is also important to prevent the occurrence of cracks and tears in the PTFE tube wall.

When a long body having three or more tube holes is used, the wall between the tube holes is cut at one end so that two or more tube holes are connected to each other, if desired. Then, a large-diameter tube hole may be formed, and one or more tube holes may be left as they are. Further, for example, in the case of an elongated body having four tube holes as shown in FIG. 7, at one end, a wall between two tube holes is cut to form two large hole tube holes. You may let me. That is, the branch tube of the present invention may have an additional tube hole, or may have a structure in which a plurality of branch tubes are integrated. Similarly, 3
In the case of using a long body having three or more tube holes, the locations (branch locations) where the branch pipes are formed may be separated from each other at the other end.

The present invention provides a branch tube having a smooth inner surface with no connections, and does not regulate the taking of other value-added measures. For example, in order to improve the maintainability of the tube hole structure and the suture strength during suturing, Japanese Patent Publication No. 58-1656 and Japanese Patent Publication No. 63-23.
According to the method described in No. 215, it is also possible to give a concavo-convex structure to the outer wall of the artificial blood vessel, and take reinforcing measures such as winding an EPTFE tape around the outer wall of the artificial blood vessel. The product of the present invention does not have a defective portion that causes destruction because there is no connecting portion, but the cut end generated by cutting the pipe wall is subjected to fusion treatment during subsequent heat shaping, but in the present invention product. It is the only part that can cause tube breakage. However, these problems can be easily solved by taking many uncut parts, separately heating and melting the cut parts, or by taking reinforcement measures only on the cut parts on the outer wall.

The product of the present invention obtained by the above manufacturing method has the following features. (1) Since it has a smooth inner surface with no connection part, it can minimize the generation of thrombus when used for an artificial blood vessel. (2) Since it can be stretched in the production stage of a long body, the stretched porous body tube has a uniform fine fibrous structure, and it is possible to uniformly cause good organizing and healing based on the porous structure. .

Further, the manufacturing method of the present invention is excellent in the following points. (1) It is possible to obtain a uniform fine fibrous structure relatively easily as compared with batch processing using a hollow mold having a branched structure. (2) Compared to the connection method, it is easier to guarantee the strength, and the reinforcing measures are unnecessary or required. Further, the reinforcement does not impair the porous structure, and in the use of an artificial blood vessel, it is possible to maintain the necessary flexibility for handling at the time of transplantation and adapting to the site / shape to be transplanted. (3) The operation is simple and the cost is low.

According to the present invention having the above-mentioned features, it is possible to easily provide a branched artificial blood vessel capable of achieving unprecedentedly high patency and curability. Of course, the branch tube of the present invention can be used in many applications other than artificial blood vessels, and the material is not limited to PTFE.

[0037]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Example 1] PTFE fine powder (PTFE fine powder F10 manufactured by Daikin Industries, Ltd.)
4) Dies having 23 parts by weight of DRYZOL as an auxiliary agent with respect to 100 parts by weight, and having a die surface having a shape shown in FIG. 3 (core pin diameter r = 1.5, distance d between core pin and die inner surface d = 0) .5) was formed into a tube shape having a cross section of 8 using a ram extruder, and then 50 parts of dryzole was used.
It was dried at ℃ for 48 hours. This extruded tube was stretched by 500% while being heated in a hot air circulation furnace under the conditions of a furnace temperature of 350 ° C. and a residence time in the furnace of 120 seconds, and a porosity of 75%, an average fiber length of 30 μm, and an inner diameter of 1.2 mmφ were used to form 2 tube holes. In other words, a tube-shaped EPTFE tube having a section 8 with a wall thickness of the tube hole of 0.5 mm was obtained.

Next, as shown in FIGS. 4 to 5, at one end of the EPTFE tube having the cross section 8, the tube wall is cut by a line connecting the centers of the tube holes, and at the other end, by the center line of the tube hole. The tube wall was cut, leaving the central 1 cm uncut. Into this tube hole, insert a stainless rod that branches into two with a smooth curve from 3 mmφ to 1.5 mmφ, fix each end of the tube to the stainless rod, and then put it in a constant temperature bath at 330 ° C. for 10 minutes for shaping. did. The stainless rod was removed to obtain a branched artificial blood vessel having an inner diameter of 3 mmφ before branching and an inner diameter of 1.5 mmφ after branching.

[Example 2] Instead of being placed in a thermostat of 330 ° C for 10 minutes, the inner surface of the furnace had an inner diameter of 35 mmφ and a length of 25.
In the electric furnace made of quartz glass tube of cm, the furnace temperature was 800 ° C, and the staying time in the furnace was 20 seconds before the branch and 7 seconds after the branch.
Except for providing an uneven structure with a depth of 50% on the outer surface of the artificial blood vessel,
In the same manner as in Example 1, a branched artificial blood vessel having an inner diameter of 3 mmφ before branching and an inner diameter of 1.5 mmφ after branching was obtained.

[Example 3] PTFE fine powder (PTFE fine powder F10 manufactured by Daikin Industries, Ltd.)
4) 23 parts by weight of DRYSOL was mixed with 100 parts by weight as an auxiliary agent, and a die having a die surface having a shape shown in FIG. 3 (core pin diameter r = 6, distance between core pin and die inner surface d = 1.5) was used. ) Using a ram extruder to form a tube with a cross section of 8 and then drysol at 50 ° C. for 4 hours.
It was dried for 8 hours. This extruded tube was stretched 400% while being heated in a hot air circulation furnace under the conditions of a furnace temperature of 400 ° C. and a residence time in the furnace of 500 seconds, a porosity of 75% and an average fiber length of 3
A tube-shaped EPTFE tube having a cross-section of 8 and having a wall thickness of 1.4 mm and having a tube hole of 0 μm and an inner diameter of 5 mmφ was obtained.

Next, as shown in FIGS. 4 to 5, at one end of the EPTFE tube having the cross section 8, the tube wall is cut by a line connecting the centers of the tube holes, and at the other end, by the center line of the tube hole. The tube wall was cut, leaving the central 1 cm uncut. Into this tube hole, insert a stainless rod branching into two with a smooth curve from 3 mmφ to 1.5 mmφ, and fix each end of the tube to the stainless rod.
An electric furnace made of a quartz glass tube of mφ and a length of 25 cm has a furnace temperature of 800 ° C., a residence time in the furnace of 120 seconds at the front of the branch and 30 seconds at the rear of the branch, and an uneven structure with a depth of 50% on the outer surface of the artificial blood vessel. Was set up. Remove the stainless steel rod to get an inner diameter of 12 before branching.
A branched artificial blood vessel having a diameter of mmφ, an inner diameter of 6 mm after branching, and a wall thickness of 1.3 mm was obtained.

Measurement of Physical Properties Physical properties of the artificial blood vessels obtained in Examples 1 to 3 were measured by the following methods. The methods for measuring the physical properties are as follows. <Average fiber length> Average value of internodal distance measured with a scanning electron microscope. <Bubble point> The pressure at which bubbles first appear when the artificial blood vessel is impregnated with isopropyl alcohol and the inside of the tube wall is filled with isopropyl alcohol, and then air pressure is gradually applied from the inside of the tube. <Leakage pressure> The water pressure when water comes out from the outer wall of the artificial blood vessel for the first time when the water pressure is gradually applied from the inside of the artificial blood vessel. <Rupture pressure> Water pressure is applied to the lumen of the artificial blood vessel, and this pressure is adjusted to 0.5.
The pressure of water when the water is broken from the artificial blood vessel wall when the pressure is gradually increased at a rate of kg / cm ² · min. <Patency rate> The ratio of the number of artificial blood vessels in which blood flow was observed at the time after transplanting the artificial blood vessels and keeping them alive for a certain period to the total number of the transplanted artificial blood vessels.

The measurement results are as follows. (1) The artificial blood vessels obtained in Examples 1 to 3 were observed on the inner surface with a scanning electron microscope. As a result, all artificial blood vessels had an average fiber length of 30 μm over the entire surface.
Had a smooth inner surface, and the porous structure was retained except that the crotch part of the branch part had a somewhat collapsed part of the porous structure. In addition, the trace of cutting the tube hole in front of the bifurcation
Although it was raised from the surroundings by about 10 μm, the change was smooth, and it was barely noticeable when the tube hole surface was squinted. In addition, the change in diameter of the bifurcation was smooth, and there were no defective parts such as cracks.

(2) With respect to the artificial blood vessels obtained in Examples 1 to 3, the bubble point and the leak pressure were measured. As a result, the bubble point was 0.15 kg / cm in Example 1.
² , 0.10 kg / cm ² in Example ² , 0.2 in Example 3
It was 0 kg / cm ² , and in each case, fine bubbles were uniformly generated over the entire length of the artificial blood vessel, and pinholes and the like did not exist. The leak pressure is 0.3 in the order of Examples 1, 2, and 3.
1 kg / cm ² , 0.25 kg / cm ² , 0.39 kg /
It was as high as cm ^2, and it was determined that blood leakage did not occur during transplantation. The distribution of the blood-leakage part was also uniformly generated over the entire artificial blood vessel.

(3) The rupture pressure of the artificial blood vessels obtained in Examples 1 to 3 was measured. As a result, 4.2 kg / cm ² , 3.5 kg / cm ² , 2.9
It was as high as kg / cm ^2, and both burst at the site immediately before branching. It was found that it has a pressure resistance sufficiently higher than blood pressure, but EP
The pressure resistance can be further increased by reinforcing the TFE tape by winding and fusing.

(4) Branch length 2 cm, branch front 2 cm,
The artificial blood vessels obtained in Examples 1 and 2 each having an uncut portion of 1 cm and a total length of 5 cm were subjected to complete replacement transplantation at the bifurcations from the abdominal aorta of rabbits weighing 13 to 15 kg to the iliac arteries on both sides. After growing for 1 day, 3 days, and 4 weeks after transplantation, the artificial blood vessel was taken out, the patency rate was investigated, and then the inner surface properties were visually observed. Further, in the sample 4 weeks after the transplantation, after visual observation, it was fixed with formalin to prepare a pathological tissue specimen, and the state of organizing was observed.

As a result, the artificial blood vessels of Examples 1 and 2 were
The patency rate is 100% in 1 to 3 days and 8 even after 4 weeks have passed.
It was as good as 3%. The inner surface of the artificial blood vessel was covered with a thin white uniform inner membrane for 1 to 3 days, and no thrombus was observed. In addition, at 4 weeks after the transplantation, the pseudointimal membrane having the same thin thickness was maintained, and the adhesion of thrombus was not observed. Four weeks after the transplantation, in the pathological tissue search of the sample, the biological tissue containing cells actively invaded from the outside into the artificial blood vessel wall, and particularly in the artificial blood vessel of Example 2, the artificial blood vessel wall contained biological tissue containing cells. It was filled in the wall, and was well organized. In addition, the innermost surface of the pseudointimal membrane was covered with vascular endothelial cells, indicating good healing properties.

[0049]

According to the present invention, there is provided a method for manufacturing a branched tube by a relatively simple method. Also, according to the present invention, there is provided a branched tube having an inner surface that is smooth and has no joints or joints as in the case of a straight tube having a single tube hole.

Since the branched artificial blood vessel obtained by the production method of the present invention has an extremely smooth tube surface without seams or connecting portions, turbulent flow is originally generated to distribute blood flow. It can be suitably used for a blood flow branch point that is likely to occur and is likely to be blocked by thrombus formation. In addition, since the porous structure that promotes organizing healing is also homogeneous and has no crushed parts, it is possible to complete organizing for living blood vessels within a very short period of time after transplantation, and to stabilize the formed tissue. A good patency rate can be achieved for a long time by the endothelial cell layer.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a branch tube of the present invention.

FIG. 2 EPTFE as a base material of the branch tube of the present invention
It is a schematic diagram which shows an example of a tube.

FIG. 3 is a cross-sectional view showing an example of a die surface shape of an extrusion die used in the manufacturing method of the present invention and an arrangement with a core pin.

FIG. 4 is a perspective view of the manufacturing method of the present invention, which uses a long body having a shape in which two tube holes are arranged, and at one end, a wall between the tube holes is formed so as to connect the two tube holes together. It is sectional drawing which shows an example of the method of forming a large diameter tube hole by cutting.

FIG. 5 is a view showing a manufacturing method of the present invention, in which a long body having a shape in which two tube holes are arranged is used, and a wall between tube holes is cut at one end so as to divide each tube hole. It is sectional drawing which shows an example of the method of forming a some branch pipe.

FIG. 6 is a cross-sectional view showing an example of a method for forming a branched shape by using an elongated body having a shape in which three tube holes are arranged around a center line in the long axis direction.

FIG. 7 is a cross-sectional view showing an example of a method for forming a branched shape by using an elongated body having a shape in which four tube holes are arranged around a center line in the long axis direction.

[Explanation of symbols]

1 Large-diameter part before branch of branch tube 2 Part branched into two of branch tube 3 Cross-section of figure 8 of base material of branch tube 4 Two tube holes of base material of branch tube 5 Base material of branch tube Wall thickness of the tube hole of 6 Branch wall distance between the median lines of the two tube holes of the branch tube base material 7 Wall thickness between the inner surfaces of the two tube holes of the branch tube base material 8 Core pin (cross section) 9 Dice Inner surface 10 Distance between core pin and inner surface of die d 11 Core pin diameter r 12 Tube cross section before cutting operation to connect two tube holes into one tube hole 13 Cutting operation to connect two tube holes into one tube hole Tube section after 14 14 Surface to divide when connecting 2 tube holes into 1 tube hole 15 2 tubes with 1 tube hole Tube section before cutting operation 16 1 tube hole 2 Cutting operation into one tube Cross-section of tube after production 17 Surface for cutting when making two tubes with one tube hole 18 Surface for cutting when connecting multiple tube holes into one tube hole 19 Multiple tubes with one tube hole Surface to be cut into tubes 20 Dividing tube holes opened in the center of a long body to adjust the shape after cutting into multiple tubes having one tube hole

Claims (5)

[Claims] 1. A long body having a shape in which a plurality of tube holes are arranged around a center line in the long axis direction, and at one end of the long body,
It has a plurality of branch pipes formed by cutting the wall between the pipe holes so as to divide each pipe hole, and at the other end, a wall between the pipe holes is formed so as to connect the plurality of pipe holes to one. A branched tube having a large hole tube hole formed by cutting. 2. The branch tube according to claim 1, wherein the elongated body having a shape in which a plurality of tube holes are arranged around a center line in the major axis direction is a stretched porous body. 3. (1) Forming a long body having a shape in which a plurality of tube holes are arranged around a center line in the long axis direction, and then,
(2) At one end of the elongated body, a wall between the tube holes is cut so as to divide each tube hole to form a plurality of branch pipes, (3)
At the other end, a method of manufacturing a branch tube, characterized in that a wall between tube holes is cut so as to connect a plurality of tube holes to each other to form a tube hole having a large hole diameter. 4. An elongated body having a shape in which a plurality of tube holes are arranged around a center line in the major axis direction, and an outer surface portion of the elongated body through which a midline between the plurality of tube holes passes is a long body. An elongated body for manufacturing a branched tube, which has a shape that is constricted toward the center line of the longitudinal body in the long axis direction. 5. A plurality of elongated bodies having a single tubular hole in the major axis direction are bundled, and at one end thereof, the tubular walls of the respective elongated bodies are integrated by adhesion, and then the plurality of tubular holes are formed into one. A method for manufacturing a branched tube, characterized in that a wall between tube holes is cut so as to connect two tubes to form a tube hole having a large diameter.