JP3054421B2 - Thin tube - Google Patents

Description

The present invention relates to a thin-walled tube. More specifically, a helical metal wire embedded in a tube wall made of an elastomer is excellent in kink resistance (bending resistance), pressure resistance, flexibility, crush recovery property, elongation recovery property, etc., and is smooth inside and outside. The present invention relates to a thin tube having a surface.

[Conventional technology]

2. Description of the Related Art Conventionally, a control tube, a medical tube, and the like have a small diameter to transfer a large amount of fluid with a small diameter and to reduce the wall thickness of the tube in order to improve flexibility. However, the thinner the wall, the more kinks (bending) during use,
The tube is likely to be closed by crushing or the like. When the tube is closed, control of each device in the control tube becomes impossible. Medical tubes, on the other hand, cause serious disability and death to the patient using them.

Therefore, it has been conventionally proposed that a reinforcing material such as a wire or a synthetic fiber be spirally provided on the wall surface of the tube so that the tube has a blocking resistance (JP-A-49-30).
Nos. 914 and 58-38565).

However, when a non-metallic wire having a small Young's modulus (longitudinal modulus) is used as a reinforcing material, the wire has insufficient rigidity, so it is necessary to increase the diameter of the wire or use an elastomer having high hardness. Therefore, there is a problem that the flexibility is inferior even though the blocking resistance is improved.

When a metal wire with a large Young's modulus such as a piano wire or a stainless steel wire is used, if it is formed into a thin wall, the irregularities on the inner and outer surfaces of the tube become severe due to the torsion force coming from the repulsion of the spirally wound part of the wire. Therefore, it was necessary to increase the wall thickness, and it was difficult to balance flexibility and kink resistance. Also, even if a thin-walled product is obtained, the tube thickness is reduced with respect to the diameter of the metal wire, so when an internal pressure is applied to the tube, the metal wire and the elastomer are easily separated and rupture is likely to occur. There was a problem.

As a solution to this problem, Japanese Patent Application Laid-Open No. 61-233284 proposes a thin-walled small-diameter tube satisfying a specific relationship between an elastomer and a metal wire, and Japanese Patent Application Laid-Open No. 61-193670. The specification describes a catheter in which a thermoplastic resin is coated on a tubular member braided in a net shape or formed in a coil shape by a shape memory alloy wire showing a thermoelastic martensitic transformation.

[Problems to be solved by the invention]

The thin-walled small-diameter tube proposed in Japanese Patent Application Laid-Open No. 61-233284 is excellent in kink resistance, but recovers its original shape once the tube is crushed by an external force. There is no difficulty.

Further, the purpose of the technology disclosed in Japanese Patent Application Laid-Open No. 61-193670 is to inject a contrast agent with increased flexibility and flexibility into a conventional polyethylene catheter knitted with a stainless wire. The purpose of the present invention is to provide a catheter used for, for example, a use in which body fluid flows through the inside of the catheter, the inner surface has poor smoothness, and a wire rod containing a large amount of nickel that easily causes inflammation on the inner surface side There was a problem that was exposed. Further, according to the disclosed technique, since it is supple but thick, only a catheter having an unsatisfactory crushing recovery property and extension recovery property can be obtained, especially when the tube is closed for a long time with forceps. Was dissatisfied.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thin tube using a reinforcing material, which is excellent in kink resistance, pressure resistance, flexibility, and particularly excellent in crush recovery and extension recovery.

[Means for solving the problem]

The inventors of the present invention have made intensive studies to produce a thin-walled tube satisfying the above object, and have reached the present invention. That is, according to the present invention, a tube wall made of an elastomer having a Young's modulus (y) of 1 × 10 ² Kgf / mm ² or less and having a wall thickness (t) of 1.0 mm or less,
A thin-walled tube in which a helical metal wire having a Young's modulus (Y) of 1 × 10 ⁵ Kgf / mm ² or less and having superelasticity is embedded, wherein the helical metal wire is a superelastic alloy showing martensitic transformation, The diameter (d) of the spiral metal wire and the spiral pitch (P)
Is d <P, the K value represented by the following equation is in the range of 0.01 to 5 × 10 ⁴ , and the E value is 30 or more.

Where Y: Young's modulus of metal wire (Kgf / mm ² ) y: Young's modulus of elastomer (Kgf / mm ² ) E: Maximum elongation of tube (%) d: Diameter of metal wire (mm) D: Tube inner diameter (Mm) t: Tube wall thickness (mm) P: Spiral pitch of metal wire (mm) The elastomer used in the thin-walled tube of the present invention has a very high rigidity from the viewpoint of crushing recovery and extension recovery. Things are inappropriate. That is, in the thin-walled tube of the present invention, if the Young's modulus exceeds 1 × 10 ² Kgf / mm ² , satisfactory flexibility is not exhibited, so the elastomer having a Young's modulus of 1 × 10 ² Kgf / mm ² or less is used. Must be used. Examples of such an elastomer include soft polyvinyl chloride, polyurethane, silicone rubber, and an elastomer having a Young's modulus equivalent thereto. Among them, a segmented polyurethane comprising a soft segment and a hard segment is biocompatible. High crushability, especially high crushability and stretch recovery.
Since it has high pressure resistance and high mechanical strength, it is suitable as an elastomer used for medical tubes.

The wire of the helical metal wire used for the thin-walled tube of the present invention, the Young's modulus is 1 × 10 ⁵ Kgf / mm ² or less, preferably ⁴ × 10 4 Kgf / mm ² or less, more preferably 2 × 10 ⁴ Kgf / m
It is necessary that the superelastic alloy has a m ² or less and shows a martensitic transformation.

If the Young's modulus exceeds this, the spirally wound metal wire will
The force of spreading to release the helix is strong, breaking the elastomer or making the elastomer too thick, which is inappropriate. The metal wire is not particularly limited as long as it is a superelastic alloy exhibiting martensitic transformation. Among them, a nickel-titanium alloy is preferably used because it also has shape memory properties.

Although the shape memory property is not always necessary for realizing the object of the present invention, the actual temperature (T ° C.)
Memory processing (spiral, spiral, etc.) so as to recover to a predetermined shape at a temperature around the temperature (usually in the range of T ± 20 ° C., preferably T ± 10 ° C.)
If a wire with a circular shape or a straight line memory is used, even if the tube is deformed, it will be recovered at the time of use, so that it is always safe and secure.

The cross-sectional shape of the wire is not particularly specified, but is usually a circle,
An elliptical or square shape is used. The diameter of the metal wire in the case of an ellipse or a square is the arithmetic mean of the major axis and the minor axis.

The diameter of the metal wire may be smaller than the wall thickness of the tube, but is 0.5 mm or less, preferably 0.1 mm or less. The spiral pitch (P) of the metal wire is larger than the diameter (d) of the metal wire and is usually 3 mm or less, preferably 1 mm or less, more preferably 0.5 mm or less.

It is an important requirement of the present invention to use a thin metal wire, and when the tube diameter is usually 5 mm or less, the diameter is 0.1 mm or less,
When the tube diameter exceeds 5 mm and is 20 mm or less, a metal wire having a diameter of 0.3 mm or less is used. When the tube diameter exceeds 20 mm, a metal wire having a diameter of 0.5 mm or less is used.

In the thin tube of the present invention, the elastomer and the spiral metal wire are Is required to satisfy 0.01K5 × 10 ⁴ . Y is the Young's modulus of the metal wire (Kgf / mm ² ), y is the Young's modulus of the elastomer (Kgf / mm ² ), E is the maximum elongation (%) of the tube, d is the diameter of the metal wire (mm), and D is The inner diameter (mm) of the tube, t is the wall thickness (mm) of the tube, and P is the spiral pitch (mm) of the metal wire. The preferred range for the K value is 0.
1K 10,000, more preferably 0.5K 5,000
It is 0.

The maximum elongation rate E of the tube reinforced with the metal wire is not only important as a factor showing the recovery (extension recovery) to an external force in the length direction, but according to the experimental results of the present inventors, E is 30%. For tubes less than (1.3 times the original length), even if the value of K is within the specified range, the deformation caused by the elastomer part may remain when sandwiched with forceps for more than 60 minutes, or the tube wall Undesirably, cracks occur. That is, E30 (%), preferably E50% and Only when satisfies is satisfied, a thin-walled tube having excellent stretch recovery and crush recovery can be obtained. The maximum elongation here means the maximum length (%) that can be recovered without breaking or permanently deforming the tube when a 5 cm long tube is pulled at a speed of 1 cm / min.

Tubes having a K value of less than 0.01 have a small elongation recovery force, and recover slowly when subjected to an external force in the tube length direction. Also,
Even with metal wire reinforcement, the minimum bending radius cannot be reduced and kinks are likely to occur.When used in a small bent state, the flatness of the tube is large, and the flow rate of the fluid in the tube is remarkably reduced. It is. On the other hand, tubes with a K value exceeding 5 × 10 ⁴ have good kink resistance and elongation recovery,
The wall thickness can be small with respect to the wire diameter of the reinforcing wire rod of the tube, and the pressure resistance and durability are inferior because the wall thickness is too thin.

The tube of the present invention can be manufactured using a known method. For example, first, a thin tube is extruded by an extruder, or a solution of an elastomer is coated on a mandrel and dried to form a core tube, and then a spiral metal wire is formed on the surface of the core tube with a predetermined pitch. Wrap. After winding the helical metal wire around the core tube, the surface of the core tube is extruded and coated with an elastomer of the same or different type by an extruder, or coated with a solution of the elastomer, followed by drying. A tube can be obtained. When winding the helical metal wire around the core tube and further covering the surface with an elastomer, it is preferable that the metal wire be positioned substantially at the center of the tube wall composed of the core tube and the coating layer.

The winding of the metal wire around the core tube can also be achieved by attaching a member (coil) previously processed into a spiral shape to the core tube.

The core tube and the elastomer for coating may not be the same elastomer, but in that case, those having mutual affinity are desirable for integration. In the core tube,
When an elastomer having a hardness equal to or higher than that of the coating tube is used, a tube having more excellent flexibility and kink resistance can be obtained. In addition, it is effective to preliminarily bond the metal wire with an adhesive such as an elastomer, a polyurethane, or an epoxy resin in order to prevent the metal wire from being separated from the elastomer and to have excellent pressure resistance.

It is an important requirement of the present invention that the metal wire used is not exposed by the method as described above. When the metal wire is exposed on the outer surface of the tube, it is dangerous in handling, and when it is inserted into the body for medical use, there is a possibility that the living body may be damaged by rubbing or the like. Even when exposed to the inner surface, for example, when used for a catheter or the like for flowing a bodily fluid, the bodily fluid component at the exposed portion may be damaged, activated, or coagulated. In particular, when the metal wire used contains nickel, the wire must be embedded in the wall of the tube in order to prevent toxicity such as the inflammatory effect of nickel.

The thin tube of the present invention can be obtained as described above, and the tube in the present invention generally has an inner diameter of 30 mm or less, preferably 15 mm or less. Also, the thin wall thickness is 1.0 mm or less, usually 0.5 mm or less, preferably 0.3 mm
These are: Tubes of this inner diameter are often used in confined spaces irrespective of industrial or medical use because of their thinness, and therefore have no kinks or crushing even with a small bending radius, Is excellent, and excellent in crush recovery and elongation recovery are required. On the other hand, when flowing the fluid through the tube, it is preferable that the inside diameter is as large as possible because the pressure loss is small. Therefore, it is desired to provide a tube having a constant outer diameter which is as thin as possible and which is free from kinks and crushing even with a small bending radius, has good crushing recovery and extension recovery, and has high pressure resistance. Thick materials with a thickness exceeding 1.0 mm have good kink resistance, but have flexibility, crush recovery,
Poor elongation recovery. Further, if the inner diameter of the tube exceeds 30 mm, the flatness of the tube in a state where the tube is bent slightly even if the K value is within the above-mentioned range is undesirably large.

Surprisingly, the thin-walled tube of the present invention has a cross-sectional shape almost completely before closing, as soon as the forceps are removed even after the tube is completely closed with forceps, even though it is contained in a metal wire, and left for at least 60 minutes. It not only recovers (excellent in radial recovery), but also exhibits high elongation and recovery against the force applied in the length direction of the tube. It has excellent performance that there is no kink or crushing even under severe conditions where the radius is four times the inner diameter of the tube. The minimum bending radius refers to the minimum bending radius at which the wire is not broken or buckled when the tube is bent, and is a value measured at the center line of the tube.

Example 1 Example 1 A core tube having an inner diameter of 2.6 mm and a wall thickness of 0.12 mm was extruded from a thermoplastic segmented polyurethane elastomer having a shear hardness (A) of 85 using a conventional extruder, and the tube was inserted into a mandrel. With a small lathe, Young's modulus 7 × 10 ³ K
gf / mm ² , nickel (55%) with a diameter of 0.06 mm-titanium (45
%) A thin alloy wire (circular memory, Af point 20 ° C.) was wound at a pitch of 0.3 mm. Next, a thermoplastic segmented polyurethane elastomer of the same kind as the core tube, Shore hardness (A)
By immersing in 85% 6% tetrahydrofuran (THF) solution and coating, a flexible tube with good smoothness on the inner and outer surfaces with a wall thickness of 0.30 mm and a maximum elongation of 230% was obtained. The average value of the Young's modulus of the polyurethane elastomer in the core tube is 0.6 kgf / mm ² , and accordingly, the K value is 81.4 mm ^1.5
It is. The tube has a minimum bend radius of 3.1D when the kink occurs, the breakdown voltage is at 2.0 kgf / cm ² or more, kink resistance, pressure resistance, excellent elongation recovery both savings piping space small curved While transporting large volumes of fluid under pressure or under reduced pressure, pneumatic equipment conduits, catheters,
It was useful as a medical tube such as an endotracheal tube.

After completely closing the tube with forceps
Upon leaving for 60 minutes and removing the forceps, the shape of the tube was immediately and almost completely recovered, showing extremely excellent crushing and recoverability.

Examples 2 to 10 and Comparative Examples 1 to 5 In the same manner as in Example 1, a tube using an elastomer and a metal wire as shown in Table 1 was trial-produced, kink-resistant and closed with forceps for 60 minutes. The state of the tube when the forceps were removed was observed. Table 1 shows the values of the maximum elongation rate E (%) and K of the tube. As is clear from the table, a superelastic alloy wire showing martensitic transformation
It can be seen that when the conditions of K5 × 10 ⁴ and E30 are satisfied, an excellent tube which is excellent in kink resistance and elongation recovery property and which substantially completely returns to its original shape even when closed with forceps can be obtained.

[Effects of the Invention] According to the present invention, a helical thin metal wire that satisfies specific conditions is embedded in the inner wall of a tube made of a specific elastomer, whereby crushing recovery, kink resistance, elongation recovery, A thin tube excellent in pressure resistance and flexibility and having smooth inner and outer surfaces can be obtained.

Such tubing is used for industrial purposes, for example, as a pipe for controlling gas or liquid, which is often used under a small bending radius, or as a conduit for various devices, or for medical use, as a catheter, a pneumatic tube. The balance between moderate rigidity and flexibility during insertion, such as intraluminal tubes and surgical tubes,
It is particularly useful in fields where kink resistance during use, crush recovery, pressure resistance, and excellent biocompatibility with a smooth surface are required.

Claims (2)

(57) [Claims] 1. A tube made of an elastomer having a Young's modulus (y) of 1 × 10 ² kgf / mm ² or less and having a wall thickness (t) of 1.0 mm or less has a Young's modulus (Y) of 1 × 10 ⁵ kgf. A thin tube embedded with a helical metal wire showing superelasticity of not more than / mm ² , wherein the helical metal wire is a superelastic alloy showing martensitic transformation, and the diameter (d) of the helical metal wire and The helical pitch (P) is d <P, and the K value represented by the following equation is 0.01 to 5 ×
A thin-walled tube having a range of 10 ⁴ and an E value of 30 or more. Here, Y: Young's modulus of metal wire (kgf / mm ² ) y: Young's modulus of elastomer (kgf / mm ² ) d: Diameter of metal wire (mm) E: Maximum elongation of tube (%) D: Tube inner diameter (Mm) t: Tube wall thickness (mm) P: Spiral pitch of metal wire (mm) 2. The thin-walled tube according to claim 1, wherein the elastomer is a polyurethane elastomer.