JPH0248794B2 - USUNIKUSHOKOKEICHUUBU - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides kink resistance (bending properties) in which spiral metal wires are embedded within the tube wall made of elastomer.
This invention relates to a thin-walled, small-diameter tube that has excellent pressure resistance, flexibility, and smooth inner and outer surfaces. The thin-walled, small-diameter tube of the present invention is particularly useful as a medical tube such as a catheter. (Prior Art) Conventionally, control tubes, medical tubes, and the like have small diameters to transfer a large amount of fluid, and the wall thickness of the tubes has been made thin in order to improve flexibility. However, the thinner the wall thickness, the more likely the tube will become blocked during use due to kinking, collapse, etc. When the tube is blocked, it becomes impossible to control each device in the control tube. Medical tubes, on the other hand, can cause serious injury or death to patients using them. Therefore, in order to provide these tubes with anti-occlusion properties, it has been proposed to provide reinforcing materials such as wire rods or synthetic fibers in a spiral shape on the walls of the tubes.
(Unexamined Japanese Patent Publication Nos. 49-30914, 58-38565, etc.) (Problems to be solved by the invention) However, when using a non-metallic wire material with a small initial tensile resistivity (longitudinal modulus) as a reinforcing material, teeth,
Since the wire rod does not have sufficient rigidity, it is necessary to increase the diameter of the wire rod or use a highly hard elastomer, which causes the problem of poor flexibility even though the occlusion resistance is improved. On the other hand, when using a metal wire with a high initial tensile resistivity such as piano wire or stainless steel wire, if it is formed into a thin wall, the torsional force resulting from the repulsion of the spiral wound portion of the wire will cause the inner and outer surfaces of the tube to become extremely uneven. However, since it is inferior in pressure resistance, it is necessary to make it thicker, and it is difficult to strike a balance between flexibility and kink resistance. Furthermore, even if a thin-walled one is obtained, the tube wall thickness is thinner than the diameter of the metal wire, so when internal pressure is applied to the tube, the metal wire and elastomer are likely to separate and rupture, resulting in problems with pressure resistance. It was hot. (Means for Solving the Problems) Therefore, an object of the present invention is to provide a thin-walled, small-diameter tube that uses a reinforcing material and has excellent kink resistance, pressure resistance, and flexibility. That is, in the present invention, the initial tensile resistivity y is 1×10 ²
The wall thickness t made of elastomer is less than Kgf/mm ²
A thin-walled, small-diameter tube in which a spiral metal wire with an initial tensile resistivity Y of 1×10 ⁴ Kgf/mm ^{2 or} more is embedded in the tube wall of 0.5 mm or less, and the diameter d and helical pitch of the spiral metal wire are P with d<P and Ck
This is a thin-walled, small-diameter tube characterized in that the value is in the range of 1 to 30. However, the Ck value is a value expressed by the following formula. Ck=Y・d ⁴ /y・D・P・t ^1/2 where Y: Initial tensile resistivity of metal wire (Kgf/
mm ² ) y: Initial tensile resistivity of elastomer (Kgf/
mm ² ) d: Diameter of metal wire (mm) D: Inner diameter of tube (mm) t: Tube wall thickness (mm) P: Helical pinch of metal wire (mm) A thin-walled, small-diameter tube that satisfies the above conditions is:
It has excellent performance with no kink or collapse even under severe conditions with a minimum bending radius of 0.6 times the tube inner diameter. Here, the minimum bending radius refers to the minimum bending radius at which no bending or buckling of the wire is observed when the tube is bent, and is a value measured at the center line of the tube. For tubes with a Ck value of 1 or less, the minimum bending radius cannot be reduced even with wire reinforcement, and kinks are likely to occur. The decrease in fluid flow rate is significant. On the other hand, tubes with a Ck value of 30 or higher have good kink resistance, but the wall thickness is thin compared to the diameter of the reinforcing wire of the tube, and the tube wall is greatly indented when used with a small bending radius. The folds that occur on the inner surface cause a decrease in the flow rate within the tube and a stagnation area, and the wall thickness becomes too thin, resulting in poor pressure resistance. In fact, such a tube is rarely used with a minimum bending radius of 0.8 times or less than the inner diameter of the tube. Therefore, the minimum bending radius is usually 0.8 times or more the inner diameter of the tube, as described in the examples below, in other words, Ck
If the value is 10 or less, there is no practical problem. A small-diameter tube as used in the present invention has an inner diameter of 20 mm or less, usually 10 mm or less. Also, thin wall means a wall thickness of 0.5 mm or less, usually 0.3 mm or less. Tubes with an inner diameter of this size are often used in limited spaces, whether for industrial or medical purposes, due to their thinness, and therefore, even with a small bending radius, there is no kink or collapse, and there is no pressure resistance. is required to be excellent. On the other hand, when flowing fluid through the tube, it is preferable that the inner diameter be as large as possible because pressure loss will be small. Therefore, it is desirable to have a tube that is as thin as possible for a given outer diameter, has no kinks or collapses even at a small bending radius, and has good pressure resistance. If the wall thickness exceeds 0.5 mm, the kink resistance will be good, but the flexibility will be poor. Moreover, if the inner diameter of the tube exceeds 20 mm, even if the Ck value is within the above range, the flatness of the tube becomes large when bent to a small extent, which is not preferable. An elastomer with too high rigidity is not suitable for use in the thin-walled, small-diameter tube of the present invention.
If the initial tensile resistivity is 1×10 ² Kgf/mm ² or more, satisfactory flexibility will not be achieved. Usually polyvinyl chloride, polyurethane, silicone rubber, fluoro rubber,
Alternatively, an elastomer having an initial tensile resistivity equivalent to these may be used. Among them, segmented polyurethane consisting of soft segments and hard segments has high biocompatibility and an elongation modulus of almost 100%, so it is suitable as an elastomer for use in medical tubes. In order to keep the Ck value within the above-mentioned range in the thin-walled, small-diameter tube of the present invention, it is important to use a helical metal wire having specific performance. Such a metal wire must have an initial tensile resistivity of at least 1×10 ⁴ Kgf/mm ² or more. If the wire diameter is less than this, the wire diameter becomes too thick in order to obtain sufficient kink resistance. As the metal wire, steel wire, stainless steel wire, tungsten wire, etc. are usually used. Among them, tungsten wire is preferably used because it has a high initial tensile resistivity. The diameter of the metal wire may be smaller than the tube wall thickness, but a diameter of 0.4 mm or less, preferably 0.1 mm or less is used. Further, the pitch of the helix of the metal wire is larger than the diameter of the metal wire, usually 1 mm or less, preferably 0.5 mm or less. The tube of the present invention can be manufactured using a known method. For example, a core tube is first formed by extruding a thin tube using an extruder or by coating a mandrel with an elastomer solution and drying it, and then a spiral metal wire is placed on the surface of the core tube at a predetermined pitch. Wrap it around. After winding a spiral metal wire around a core tube, the surface of the core tube is coated with an elastomer of the same or different type as the core tube by extrusion, or by coating with an elastomer solution and drying. You can get tubes. When winding a spiral metal wire around the core tube and coating its surface with an elastomer,
Preferably, the metal wire is located approximately at the center of the tube wall consisting of the core tube and the covering layer. The core tube and the covering elastomer do not have to be the same elastomer, but in that case, it is desirable that they have mutual affinity for integration. If an elastomer having a hardness equal to or higher than that of the coating tube is used for the core tube, a tube with even better flexibility and kink resistance can be obtained. In addition, elastomer is added to the metal wire material in advance,
Adhesion treatment with an adhesive such as polyurethane or epoxy resin is effective in making it superior in pressure resistance. (Example) Example 1 Thermoplastic segmented polyurethane elastomer, Shore hardness (A) 85
After extruding a core tube with a diameter of 2.6 mm and a wall thickness of 0.12 mm, and inserting the tube into a mandrel, use a small lathe to reduce the initial tensile resistance to 3.6×10 ⁴ Kgf/mm ² and the diameter.
A 0.08mm tungsten wire was wound with a 0.3mm pitch. Next, a thermoplastic segmented polyurethane elastomer of the same type as the core tube, 6% tetrahydrofuran (THF) with a Shore hardness (A) of 80.
By immersing it in a solution and coating it, a flexible tube with a wall thickness of 0.25 mm and smooth inner and outer surfaces was obtained. The average value of the initial tensile resistivity of the polyurethane elastomer of the core tube is 0.6Kgf/mm ²
Therefore, the Ck value is 6.3mm ^1.5 . This tube has a minimum bending radius when a kink occurs.
1.3D, pressure resistance is 2.0Kgf/mm ² or more, excellent kink resistance and pressure resistance, small curvature allows for transporting large amounts of fluid under pressure or reduced pressure while saving piping space, and is suitable for pneumatic equipment. It was useful as a medical tube, such as a conduit, a catheter, or an endotracheal tube. Examples 2 to 7 and Comparative Examples 1 and 2 A tungsten wire with a diameter d (mm) was spirally wound at a constant pitch P (mm) into a core tube with an inner diameter D (mm) made of the same segmented polyurethane elastomer as in Example 1. After winding the tube into a shape, the surface thereof was coated with the above elastomer in the same manner as in Example 1 to obtain eight types of thin-walled, small-diameter tubes having tube wall thicknesses of t (mm) as shown below. Table 1 shows the relationship between the Ck value and the minimum bending radius of these tubes. Also Table-1
The results are shown graphically in Figure 1. As is clear from the graph, the minimum bending radius becomes balanced when the Ck value is 10 or more. Therefore, a Ck value in the range of 1 to 10 is practical.

[Table] (Effects of the Invention) As described above, according to the present invention, by embedding a highly rigid spiral metal wire that satisfies specific conditions into the wall of a tube made of a specific elastomer,
A small-diameter, thin-walled tube with excellent kink resistance, pressure resistance, and flexibility and a smooth surface can be obtained. In industrial applications, such tubes are used, for example, as gas and liquid control piping that is often used under small bending radii, or as conduits for various devices, and in medical applications, such as catheters and intratracheal tubes. Appropriate balance of rigidity and flexibility during insertion, such as tubes and surgical tubes, kink resistance during use,
It is particularly useful in fields where pressure resistance and excellent biocompatibility due to a smooth surface are required.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the minimum bending radius at which a thin-walled, small-diameter tube does not cause kinking and the Ck value.

Claims (1)

[Scope of Claims] 1 A tube wall with an initial tensile resistivity Y of 1×10 ⁴ Kgf/mm ² or less and a wall thickness t of 0.5 mm or less is made of an elastomer with an initial tensile resistivity Y of 1×10 ⁴ Kgf/mm 2 or less. /
A thin-walled, small-diameter tube embedded with a spiral metal wire of mm ² or more, configured such that the diameter d and helical pitch P of the spiral metal wire are d<P, and the Ck value is in the range of 1 to 30. A thin-walled, small-diameter tube characterized by: However, the Ck value is a value expressed by the following formula. Ck=Y・d ⁴ /y・D・P・t ^1/2 (mm ^1.5 ) where Y: initial tensile resistivity of metal wire (Kgf/
mm ² ) y: Initial tensile resistivity of elastomer (Kgf/
mm ² ) d: Diameter of metal wire (mm) D: Inner diameter of tube (mm) t: Tube wall thickness (mm) P: Helical pitch of metal wire (mm) 2 Claim 1 in which the elastomer is a polyurethane elastomer Thin-walled, small-diameter tube as described in section. 3. The thin-walled, small-diameter tube according to claim 1, wherein the spiral metal wire is a tungsten wire.