JP7437012B2 - catheter tube - Google Patents

Description

The present invention relates to catheter tubes.

The present inventor has discovered that one way to ensure the flexibility of a catheter tube is to use a foamed resin in the catheter tube.

As a tube made of foamed resin, for example, Patent Document 1 discloses a method for manufacturing a foamed resin tube whose surface is provided with unevenness by embossing. A method for producing such a foamed resin tube includes preparing a die provided with a first annular discharge port and a first flow path communicating with the first discharge port, and discharging a first resin containing a foaming agent from the first discharge port. By performing vacuum forming or air pressure forming in a molding device while extruding the first resin, foaming of the first resin and molding into a tube shape having an embossed pattern on the surface are simultaneously performed.

However, in medical catheters, since the catheter must be inserted into a body lumen, the surface of the catheter is required to be smooth. However, in the case of chemical foaming as in Patent Document 1 or physical foaming using gas, when forming a tube, the surface of the tube may become uneven, ragged, or have holes due to rupture due to foaming. There was a problem that there were empty spaces. There was a problem in that the surface of the tube thus produced was not improved even if the surface was smoothed by heating or the like.

WO2018/123090 publication

Therefore, the present invention has been made to solve these problems, and is a catheter tube using a resin having foam cells, which has improved flexibility and a smooth surface. It is an object of the present invention to provide a catheter tube as well as a method for producing such a catheter tube.

The present invention employs the following means to achieve the above object.

The catheter tube according to the present invention includes:
It is characterized in that the expandable microcapsules, which expand upon heating, are made of a foamed resin having foamed cells made of expanded closed cells inside.

According to the catheter tube according to the present invention, by using the foamed resin made of expandable microcapsules, the foamed cells can be made into closed cells, and the formation of unevenness on the surface due to the bursting of the foamed cells can be reduced. , and the flexibility can be improved compared to a catheter tube that does not have foam cells.

Further, in the catheter tube according to the present invention, the foamed cells may have an average diameter of 30 μm to 90 μm.

By forming the foam cells within this range, a catheter tube having higher flexibility can be obtained.

Furthermore, in the catheter tube according to the present invention, the total spatial volume of the foamed cells per unit volume may be larger than the total volume of the resin.

By making the total spatial volume of the foamed cells larger than the total volume of the resin, the catheter tube can have higher flexibility.

Furthermore, in the catheter tube according to the present invention, the surface of the catheter tube may have a smoothed surface whose unevenness is smoothed by heating.

By heating the catheter tube, fine irregularities are further smoothed and the catheter tube can have a smooth surface.

Furthermore, in the catheter tube according to the present invention, the foamed cells may have a different average diameter depending on the portion of the catheter tube.

By varying the average diameter of the foam cells depending on the location of the catheter tube, the catheter tube can have different flexibility depending on the location.

Furthermore, in the catheter tube according to the present invention,
The foamed resin may be a polyamide synthetic resin, polyamide, polyethylene, polyimide, polyether ether ketone, polyethylene terephthalate, polyurethane, or polypropylene.

Furthermore, in the catheter tube according to the present invention,
The expandable microcapsules contain one or more expanding agents selected from isobutane, pentane, ether, hexaneheptane, low-boiling halogenated hydrocarbons, and methylsilane, and vinylidene chloride, acrylonitrile, acrylic esters, and methacrylic esters. It may be characterized by being wrapped in one or more selected thermoplastic resins having gas barrier properties.

Furthermore, in the catheter tube according to the present invention,
The expandable microcapsules may be mixed in an amount of 0.5% to 7.5% by weight based on the resin.

The catheter tube described above can be produced by the following method.
(1) Expandable microcapsule mixing step in which expandable microcapsules that expand upon heating are mixed with resin. (2) Molding step in which the mixed resin is molded into a tube shape.
(3) A heating step in which the tube-shaped resin is softened and the surface is smoothed by heating at a temperature higher than that at which the expandable microcapsules can be expanded.

Moreover, in the method for producing the catheter tube described above,
It may be characterized in that the heating temperature in the heating step is 250°C or more and 300°C or less.

By heating at such a temperature, the foamed cells can be expanded to an average diameter of 30 μm to 100 μm, and the surface can be smoothed.

Furthermore, in the method for producing the catheter tube described above,
When heating in the heating step, heating may be performed at different heating temperatures depending on the region.

By employing such a method for producing a catheter tube, it is possible to produce a catheter tube that has different flexibility depending on its location.

According to the catheter tube according to the present invention, the catheter tube can be made more flexible than a catheter tube that does not include foam cells, and even though foamed resin is used, A catheter tube with a smooth surface can be provided.

FIG. 1 is a micrograph of a catheter tube 100 according to an embodiment. FIG. 2 is a flowchart of a method for manufacturing the catheter tube 100 according to the embodiment. FIG. 3 is a diagram showing variations in the state of the foam cells of the catheter tube 100 according to the embodiment. FIG. 4 is a micrograph of Example 2, Example 3, and Comparative Example. FIG. 5 is a graph showing the measurement results of flexibility (bending rigidity N) depending on the heating temperature of Examples 1 to 5 and Comparative Example. FIG. 6 is a graph showing the results of measuring the flexibility (flexural rigidity N) of Example 2, Example 3, and Comparative Example at different heating temperatures of 10° C. FIG. 7 is a diagram showing the measurement results of the average particle diameter of the foamed cells depending on the heating temperature of Example 2 and Example 3, and an external photograph. FIG. 8 is a diagram showing the measurement results of the average particle diameter of the foamed cells depending on the heating temperature of Example 2 and Example 3, and an external photograph. In addition, in FIG. 8, like FIG. 7, the upper row shows Example 2, and the lower row shows Example 3. FIG. 9 is a graph showing the results of measuring the outer diameters of Examples 2 and 3 after heating. FIG. 10 is a graph showing the measurement results of flexibility (bending rigidity N) depending on the heating temperature of Examples 6 and 7 and Comparative Examples 3 and 4.

Next, the catheter tube 100 and the method for manufacturing the catheter tube 100 according to the present invention will be described in detail with reference to the drawings. Note that the embodiments and drawings described below illustrate some of the embodiments of the present invention, and are not used for the purpose of limiting the configurations to these, and do not depart from the gist of the present invention. It can be changed as appropriate within the range.

(First embodiment)
A photograph of the catheter tube 100 according to the first embodiment is shown in FIG. The catheter tube 100 according to the first embodiment is made of a resin mixed with expandable microcapsules that expand when heated, and has expanded foam cells 10 inside, as shown in FIG. consists of a tube with a smooth surface due to heat treatment.

Such catheter tube 100 is manufactured as follows. As shown in FIG. 2, the method for producing the catheter tube 100 mainly includes an expandable microcapsule mixing step (S1), a molding step (S2), and a heating step (S3).

The expandable microcapsule mixing step (S1) is a step of mixing expandable microcapsules with resin to produce a raw material for foamed resin. Expandable microcapsules have a thermoplastic resin outer shell and a substance that vaporizes when the temperature is raised. It is a substance that expands to become a hollow microballoon. The expandable microcapsules are not particularly limited, and known ones can be selected. For example, examples of the resin constituting the outer shell include thermoplastic resins having gas barrier properties such as vinylidene chloride, acrylonitrile, acrylic esters, and methacrylic esters. Internal materials include, for example, isobutane, pentane, ether, hexaneheptane, low boiling halogenated hydrocarbons, and methylsilane. A preferred material is one in which the inner material is made of liquid aliphatic hydrocarbon and the outer shell is wrapped in an acrylic thermoplastic resin. Examples of the resin with which the microcapsules are mixed include polyamide synthetic fibers such as nylon, polyamide, polyethylene, polyimide, polyether ether ketone, polyethylene terephthalate, polyurethane, and polypropylene. As for the mixing method with the resin, it is preferable to directly mix the microcapsules with the powdered resin. The expandable microcapsules are about 0.5% to 7.5% by weight, preferably about 1.5% to 7.5% by weight, more preferably about 1.5% to 4.5% by weight based on the resin. It is advisable to mix them by weight%. If it is less than 0.5% by weight, the air bubble ratio in the resin will be small and the bending rigidity will decrease too little, making it impossible to ensure sufficient flexibility. If it exceeds 7.5% by weight, microcapsules may Unevenness may occur on the surface of the tube, reducing surface smoothness. When a resin mixed with such microcapsules is heated, the microcapsules expand, become hollow spheres, and are dispersed within the resin, forming a foam consisting of almost closed cells. By using such a foam made of microcapsules, the size of the foam cells can be controlled by the size of the expandable microcapsules and the heating temperature, so by adjusting these, the flexibility of the catheter tube 100 can be increased. It can be selected and produced.

The molding step (S2) is a step of molding the resin mixed with expandable microcapsules into a tube shape. The molding method is not particularly limited as long as it is a molding method used for resin molding. For example, it may be formed by extrusion molding. The thickness and length of the molded catheter tube 100 are not limited, and are appropriately selected depending on the purpose of use, such as a catheter for the digestive tract, a catheter for the urinary tract, a catheter for blood vessels, a microcatheter, etc. Note that at this stage, the expandable microcapsules have not expanded to the desired size, and are either not expanded at all or expanded incompletely.

The heating step (S3) is a step of smoothing the surface of the catheter tube 100 and expanding the expandable microcapsules to form foam cells of a desired size. The catheter tube 100 that has undergone the molding process has an uneven surface with expandable microcapsules partially protruding from the surface. Therefore, it is heated to make the surface smooth. Further, in this step, a step of expanding the expandable microcapsules to a desired size and a step of shrinking the expandable microcapsules as necessary are performed at the same time. The heating step is performed by allowing the resin to stand still at a temperature that softens the resin and expands (foams) the expandable microcapsules. The preferred temperature is 210°C or more and 300°C or less, more preferably 220°C or more and 290°C or less, and even more preferably 260°C or more and 280°C or less. By heating the catheter tube 100 at such a temperature, the irregularities on the surface are removed and the surface becomes smooth, and at the same time, the internal expandable capsule expands due to the heating to form foam cells. If the temperature is less than 210°C, the expandable microcapsules will not expand sufficiently, making it impossible to ensure sufficient flexibility, and the expanded cells formed by the expandable microcapsules exceeding 300°C will burst, causing unevenness on the tube surface. This may occur, making it impossible to maintain smoothness. Furthermore, depending on the resin selected, it will shrink and the diameter of the tube will become smaller. The foamed cells are preferably expanded to a diameter of approximately 30 μm to 100 μm. This is because if it is smaller than 30 μm, the effect on improving the flexibility of the catheter tube will be small, and if it is larger than 90 μm, the outer shell of the expandable macrocapsule may rupture. Further, by foaming so that the total spatial volume of the foamed cells becomes larger than the total volume of the resin, flexibility and flexibility can be further improved.

The catheter tube 100 produced as described above can have improved softness and flexibility compared to a catheter tube that does not have foam cells that have the same outer diameter.

Note that the flexibility of the catheter tube 100 may be changed depending on the region by changing the temperature of the heating process depending on the region. For example, as shown in FIG. 3A, only the expansible microcapsules at the tip are heated to form a foamed cell 10 in which only the expansible microcapsules at the tip are foamed to improve the flexibility of only the tip, or as shown in FIG. 3B. As shown in FIG. 3C, the foamed cells 10 are formed only in a part of the catheter tube 100 to improve flexibility, or the distal end is heated at a high temperature and then the proximal end is heated as shown in FIG. 3C. By lowering the heating temperature accordingly, it is possible to form smaller foam cells in order from the foam cells 10a on the distal end side to the foam cells 10b and 10c as they come closer to the proximal side. The catheter tube 100 produced in this manner can be made soft on the distal end side and hard on the proximal side.

(Example)
Nylon elastomer PEBAX (manufactured by Arkema) is used as the resin for the catheter tube 100, and microspheres (manufactured by Kureha Co., Ltd.), which are microcapsule pellets containing 50% expandable microcapsules, are used as the compounding material for the expandable microcapsules. ), and the actual amount of microcapsules (half the amount of pellets) was 0.5% by weight (Example 1), 1.5% by weight (Example 2), and 4.5% by weight (Example 2), respectively. Example 3), 6.0% by weight (Example 4), and 7.5% by weight (Example 5) were mixed and extruded to produce a microcatheter tube with an inner diameter of 0.55 mm and an outer diameter of 0.65 mm. . As comparative examples under the same conditions, microcatheter tubes were prepared using only nylon elastomer PEBAX without mixing expandable microcapsules (Comparative Example 1), and tubes for microcatheters were prepared using only nylon elastomer PEBAX without mixing expandable microcapsules (Comparative Example 1), and tubes with 0.25% by weight of expandable microcapsules mixed ( Comparative Example 2) was similarly extruded to produce a microcatheter tube. In addition, when the mixture was mixed at 10.0% by weight, the tube became crumbly during extrusion molding and could not be molded. This is thought to be due to the excessive presence of microcapsules, which impaired the moldability of the tube.

FIG. 4 shows micrographs of Comparative Example 1, Example 2, and Example 3 after extrusion molding and before the heating step. At this stage, in both Examples 2 and 3, fine foam cells were observed inside the catheter tubes, but they were hardly expanded. The surface was slightly uneven, and Example 3, which contained a higher amount of expandable microcapsules, had more unevenness. On the other hand, in Comparative Example 1, almost no foaming was observed inside.

Next, as a heating step, Examples 1 to 5 and Comparative Examples 1 and 2 were heated at 220°C, 240°C, 260°C, and 280°C, and the bending rigidity (N) of each was measured. The bending rigidity was evaluated by measuring the force when the sample was supported at a distance of 3 mm between two points and the center was pushed down by 0.5 mm at a speed of 20 mm/sec. The measurement results are shown in FIG. In Comparative Example 1 and Comparative Example 2, the bending rigidity did not decrease significantly even when heated, and no significant change was observed in the improvement of flexibility. On the other hand, in Examples 1 to 5, when heated to 220°C, the bending rigidity decreased and the flexibility improved compared to Comparative Examples 1 and 2. It can be confirmed that the performance has improved.

Next, regarding Example 2 and Example 3, the bending rigidity (N) was measured at every 10°C between 200°C and 290°C. The measurement results are shown in FIG. According to these measurement results, it can be seen that the flexibility significantly improves from 210°C, and further increases significantly at 260°C. Note that when heated to 300° C., the foam cells burst due to excessive heating, and unevenness occurred on the surface of the catheter tube. From this, it can be seen that a heating temperature of 210° C. to 290° C. is suitable for improving the flexibility of the catheter tube.

Next, regarding Examples 2 and 3, the average particle diameter of the foamed cells was measured at every 10°C between 200°C and 290°C, and the appearance was inspected. Microscopic photographs of the average particle diameter and appearance of each foamed cell are shown in FIGS. 7 and 8. From this measurement result and the measurement result shown in FIG. 6, it can be seen that the average particle diameter of the foamed cells is preferably 30 μm to 90 μm in order to improve the flexibility of the catheter tube.

Next, the outer diameters of Example 2 and Example 3 after the heating process were measured. The measurement results are shown in FIG. It was confirmed that the outer diameters were reduced to 0.566 mm and 0.576 mm, respectively, compared to before heating, and that they were shrunk. Further, in the visual inspection, it was confirmed that the surfaces of Examples 2 and 3 were smooth.

Furthermore, polyethylene (Nipolon F14 manufactured by Tosoh Corporation) was used as the resin for the catheter tube 100, and microspheres (Kureha Co., Ltd.) were used as microcapsule pellets containing 50% microcapsules as the compounding material for the expandable microcapsules. (Example 6), a styrene elastomer (Tuftec H1052 Asahi Kasei Co., Ltd.) was used instead of polyethylene, and a 4.5% by weight mixture of expandable microcapsules (half the amount of pellets) was used (Example 6). A tube for a microcatheter was prepared using only polyethylene (Nipolon F14 manufactured by Tosoh Corporation) (Comparative Example 3), and a styrene-based elastomer (Tuftec H1052 stock) was used (Example 7). The bending rigidity (N) of a tube for a microcatheter (Comparative Example 4) was measured using only a microcatheter tube (manufactured by Asahi Kasei) heated to 220°C, 240°C, 260°C, and 280°C. . The measured results are shown in FIG. According to FIG. 10, Examples 6 and 7, which used polyethylene as a resin and styrene elastomer, were more flexible than Comparative Examples 3 and 4, which were unblended products that did not use expandable microcapsules. It was confirmed that the rigidity was reduced and the flexibility was improved.

100... Catheter tube, 10... Foamed cell

Claims (10)

Expandable microcapsules that expand upon heating are made of a foamed resin that has foamed cells made of expanded closed cells inside;
The catheter tube according to claim 1, wherein the foam cells have different average diameters depending on the portion of the catheter tube. The catheter tube according to claim 1, wherein the foam cells have an average diameter of 30 μm to 90 μm. 3. The tube for a catheter according to claim 1, wherein the total spatial volume of the foam cells per unit volume is larger than the total volume of the resin. The catheter tube according to any one of claims 1 to 3, wherein the surface of the catheter tube has a smoothed surface whose unevenness is smoothed by heating. The catheter tube according to any one of claims 1 to 4, wherein the foamed resin is a polyamide synthetic resin, polyamide, polyethylene, polyimide, polyether ether ketone, polyethylene terephthalate, polyurethane, or polypropylene. . The expandable microcapsules contain one or more expanding agents selected from isobutane, pentane, ether, hexaneheptane, low-boiling halogenated hydrocarbons, and methylsilane, and vinylidene chloride, acrylonitrile, acrylic esters, and methacrylic esters. The catheter tube according to any one of claims 1 to 5, characterized in that it is wrapped in one or more selected thermoplastic resins having gas barrier properties. 7. The catheter tube according to claim 1, wherein the expandable microcapsules are mixed in an amount of 0.5% to 7.5% by weight based on the resin. (1) Expandable microcapsule mixing step in which expandable microcapsules that expand upon heating are mixed with resin.
(2) A molding process in which the mixed resin is molded into a tube shape.
(3) A heating step in which the tube-shaped resin is softened and the surface is smoothed by heating at a temperature higher than that at which the expandable microcapsules can be expanded.
A method for producing a catheter tube, the method comprising: 9. The method for manufacturing a catheter tube according to claim 8, wherein the heating temperature in the heating step is 250° C. or more and 300° C. or less. 10. The method for producing a catheter tube according to claim 8, wherein the heating step is performed at different heating temperatures depending on the region.

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