JP3416939B2 - Plastic needle for indwelling in the body and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic needle for indwelling in a body and a method for manufacturing the same, and more particularly, a method for processing the tip of a plastic needle by heating and stretching a polyurethane shape memory resin tube, and a method for manufacturing the same. Plastic needles.

[0002]

2. Description of the Related Art Conventionally, when transfusing blood or infusion,
A catheter (indwelling needle) that is temporarily placed in a blood vessel is often used. The indwelling needle generally consists of an outer needle made of thermoplastic resin and an inner needle made of stainless steel.After inserting the inner needle into the outer needle and inserting it into the body, the inner needle is removed and the remaining outer needle is transfused. Use by connecting a set or infusion set. The tip of the indwelling needle outer needle is made thin in order to reduce resistance when it is inserted into the body, and is manufactured so that the step with the inner needle is made as small as possible. As a material for forming the outer needle, polytetrafluoroethylene (PTFE), polyurethane, polyethylene, etc. have been conventionally used, and as a method for processing the tip, a grinding method or a method using a molding die is used. Has been adopted.

[0003]

However, when manufacturing an outer needle of an indwelling needle using a polyurethane shape memory resin tube, the conventional tip processing method has the following problems. That is, the method of grinding the tip has a drawback that dust adheres to the surface of the tube because static electricity is generated by the grinding, and the method of using a molding die is the method of using the tip of the polyurethane shape memory resin tube. It has a drawback that the processing time becomes long because the molding cannot be done unless the mold is pressed against the mold and cooled in this state and then taken out from the mold. The present invention has been made in view of the above circumstances, and a method for producing a plastic needle for indwelling in a body (outer needle of an indwelling needle) having a small piercing resistance using a polyurethane-based shape memory resin tube and an outer needle thereof are provided. The purpose is to provide.

[0004]

In order to solve the above problems, the present invention provides, as a first invention, a plastic hub attached to one end of a polyurethane shape memory resin tube, and the tube-hub assembly. The metal mandrel is inserted into the solid body to fix the hub, the other end of the tube is fixed to a fixture movable in the longitudinal direction of the tube, and the tube is fixed at the both ends at a predetermined position of the tube of the hub assembly. While heating at a temperature not lower than the glass transition point and not higher than the melting point, the fixture is moved to stretch the tube until the wall thickness at the predetermined position becomes 0.05 mm or less, and then with a mandrel.
It employs a method of manufacturing a plastic needle for indwelling in the body, which is characterized in that the minimum wall thickness of the tube that is not fixed is cut. Here, the solution viscosity of the polyurethane-based shape-memory resin is 0.5 or more, elongation at break at 110 ° C. of tube 1100% or more, preferably an elastic modulus at 110 ° C. that is 520 g / mm ² or less.

[0005]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is an explanatory diagram of a plastic needle of the present invention, and FIGS. 2 to 4 are explanatory diagrams of a manufacturing method of the present invention. As shown in FIG. 1, the plastic needle 1 of the present invention
Is the one in which the hub 12 is attached to one end of the tube 11, and the tip portion 13 of the tube 11 is formed to have a wall thickness of 0.05 mm or less. The tube 11 is made of a polyurethane type shape memory resin, and the thickness of the tip portion 13 is reduced to 0 by heating and stretching at a temperature not lower than the glass transition point and not higher than the melting point.
It is formed to be 05 mm or less. With this method, the molding conditions such as heating range, heating temperature, heating time, stretching distance, stretching speed, heat setting time by reheating, and cooling time can be made constant, so that the tip is always constant. The shape can be obtained. The solution viscosity of the polyurethane-based shape memory resin used is 0.5 or more, and the tube formed of this polyurethane-based shape memory resin is
It is preferable that the elongation at break at 1 ° C. is 1100% or more and the elastic modulus at 110 ° C. is 520 g / mm ² or less. still,
The plastic needle 1 of the present invention, as shown on the left side of FIG.
It is used with the inner needle 2 having the hub 3 attached at the base end thereof.

The size of the tube 11 is usually in consideration of the smooth flow of infusion, insertion into a blood vessel, strength and flexibility.
The inner diameter is 0.4 to 1.4 mm, the wall thickness is 0.05 to 0.25 mm, and the length is 15 to 70 mm. The elongation at break of the tube 11 is 1
In order to reduce the defective rate due to tube breakage during the stretching process of No. 3, it is set to 1100% or more at 110 ° C. In this case, the defect rate can be 5% or less (see FIG. 5). Further, since the solution viscosity of the polyurethane-based shape memory resin is proportional to the breaking elongation of the tube formed of the resin, a resin having a solution viscosity of 0.5 or more, preferably 0.6 or more is adopted ( (See FIG. 6). Further, the elastic modulus of the tube 11 and the fitting value between the inner needle formed of stainless steel and the plastic needle are in inverse proportion to each other, and when the fitting value is 20 g or less, the fitting becomes loose, In order to prevent the tube 11 from falling off before use, the elastic modulus of the tube 11 is set to 520 g / mm ² or less (see FIG. 7).

Next, a method of manufacturing the plastic needle 1 of the present invention will be described. The plastic needle 1 as described above,
After the hub 12 made of plastic such as polypropylene, polyethylene or polycarbonate is attached to one end of the tube 11 made of polyurethane type shape memory resin to form a tube-hub assembly, the tube 11 of this tube-hub assembly is formed. It is formed by processing the tip portion 13 of the. The tip portion 13 of the tube 11 is processed by a first step (FIG. 2) of inserting a predetermined position (tip portion) of the tube 11 into a heater for heating as shown in FIGS. 2 to 4 while heating the tip portion. It comprises a second step of stretching (FIG. 3) and a third step (FIG. 4) of cutting the tip portion stretched in the second step at the minimum wall thickness portion.

Next, processing of the tip portion 13 of the tube 11 will be described in more detail. First, as shown in FIG.
The metal mandrel 4 is inserted into the tube-hub assembly to fix the hub 12 to the hub fixture 6, and the tip portion of the tube 11 is inserted into the heater 5 for heating (first step).
Next, the other end of the tube 11 is fixed by a fixture 7 that is movable in the longitudinal direction of the tube 11 as shown in FIG. 3, and the tip portion of the tube 11 is heated by a heater 5 to a temperature not lower than the glass transition point and not higher than the melting point. The hub fixture 6 is moved in the longitudinal direction while being heated. Next, the tube 11 (more accurately, the tip end portion of the tube) was
After stretching to less than mm, the minimum thickness part (Fig. 4
The cutting position 8) may be cut with a cutter (not shown).

[Test Example 1] Ester type polyurethane resin: MM4510 (manufactured by Mitsubishi Heavy Industries, Ltd.) with an outer diameter of 0.87
A tube with a diameter of ± 0.06mm and an inner diameter of 0.65 ± 0.03mm is formed. At an ambient temperature of 110 ± 0.5 ℃, a chuck distance of 12.5mm, and a pulling speed of 500mm / min. The ratio) was measured and the relationship with the defective rate due to the breakage of the tube was determined, and the result as shown in FIG. 5 was obtained. From the figure, it is understood that the failure rate due to the breakage of the tube is 1100% or less at the breaking elongation and 5% or less.

Test Example 2 The same ester-based polyurethane resin as in Test Example 1 was dissolved in dimethylacetamide to prepare a solution of 0.1.
When a 3 g / dl dimethylacetamide solution was prepared and the logarithmic viscosity was measured at an atmospheric temperature of 30 ° C. using an Ostwald viscometer, the results shown in FIG. 6 were obtained. The figure shows that there is a correlation between solution viscosity and elongation at break.
The logarithmic viscosity (ηinh) is calculated by the equation: ηinh = ln (t / t ₀ ) / c
It was calculated by Where t: 0.3 g / dl resin drop time of dimethylacetamide solution t ₀ : Dimethylacetamide (solvent) drop time c: Solution concentration (g / dl)

Using a tube similar to that of Test Example 1, the elastic modulus (tensile elastic modulus: JIS K7113) at an atmospheric temperature of 110 ± 0.5 ° C., a chuck distance of 12.5 mm, and a pulling speed of 500 mm / min.
Was measured, and the results shown in FIG. 7 were obtained.
From the figure, it can be seen that the fitting value is 20 g or more when the elastic modulus is 520 g / mm ² or less.

[0012]

As is apparent from the above description, by adopting the present invention, it is possible to provide a plastic needle for indwelling in a body having a stable distal end shape and a small piercing resistance, which is physically applicable to the patient. Can reduce pain.

[Brief description of drawings]

FIG. 1 is an explanatory view of a plastic needle of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing method of the present invention.

FIG. 3 is an explanatory diagram of a manufacturing method of the present invention.

FIG. 4 is an explanatory diagram of a manufacturing method of the present invention.

FIG. 5 is a diagram showing a relationship between a breaking elongation of a tube and a defective rate due to the breaking.

FIG. 6 is a diagram showing the relationship between the solution viscosity and the elongation at break of the polyurethane shape memory resin used in the present invention.

FIG. 7 is a diagram showing a relationship between an elastic modulus of a tube and a fitting value.

[Explanation of symbols]

1 plastic needle 11 tubes 12 hubs 13 Tip 2 inner needle 3 hubs 4 Mandrel 5 heater 6 Hub fixing tool 7 Fixture

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 1-249067 (JP, A) JP-A 3-60672 (JP, A) JP-A 57-29365 (JP, A) JP-A-3- 60672 (JP, A) JP-A 50-158195 (JP, A) JP-A 61-76152 (JP, A) JP-A 5-84293 (JP, A) Actual Kaihei 2-1159 (JP, U) Japanese Patent Publication Sho 49-5433 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61M 5/158

Claims (4)

(57) [Claims] 1. A polyurethane-based shape memory resin tube having a plastic hub attached to one end thereof, a metal mandrel inserted through the tube-hub assembly to fix the hub, and the other end of the tube extending longitudinally of the tube. The tube is fixed to a fixture that is movable in the direction, and while heating the predetermined position of the tube of the tube-hub assembly fixed at both ends at a temperature of not less than the glass transition point and not more than the melting point, the fixture is moved to move the tube. After stretching until the wall thickness at the specified position becomes 0.05 mm or less, the tube that is not fixed with the mandrel
A method for manufacturing a plastic needle for indwelling in a body, which comprises cutting a minimum wall thickness portion of a tube . 2. The polyurethane-based shape memory resin has a solution viscosity of 0.5 or more, a rupture elongation at 110 ° C. of the tube of 1100% or more, and an elastic modulus at 110 ° C. of 520.
The production method according to claim 1, which is g / mm ² or less. 3. A plastic needle in which a plastic hub is attached to one end of a polyurethane shape memory resin tube, and the tip of the tube is heated and stretched at a temperature not lower than the glass transition point and not higher than the melting point to give a thickness of 0.05 mm or less. The manufacturing according to claim 1, wherein the manufacturing is performed in a thick wall.
A plastic needle for indwelling in the body obtained by the method . 4. The polyurethane-based shape memory resin has a solution viscosity of 0.5 or more, a rupture elongation of the tube at 110 ° C. of 1100% or more, and an elastic modulus at 110 ° C. of 520.
The plastic needle for indwelling in the body according to claim 3, which has a g / mm ² or less.