JP2001205689A - Method for manufacturing polyurethane thermoplastic elastomer tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tube made of a polyurethane thermoplastic elastomer which is vitreous at a normal temperature and has shape memory properties, with such advantages that the degree of thermal shrinkage is lower than that of a conventional elastomer tube and a reliable dimensional stability is ensured in manufacturing. SOLUTION: The polyurethane thermoplastic elastomer which is vitreous at a normal temperature and has shape memory properties is molded in the form of a tube using an extruder which is set in such a way that the temperature of a cylinder gradually rises from a spot near a material supply aperture to a tip part on the die side so that the temperature of the tip part is 230 deg. or higher and the temperature of a die is lower than that of the tip part on the die side of the cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyurethane-based thermoplastic elastomer tube, and more particularly to a method for producing a tube made of a polyurethane-based thermoplastic elastomer having a glassy state at room temperature and having shape memory properties.

[0002]

2. Description of the Related Art An extruder used for extrusion molding of a synthetic polymer material is usually mounted on a hopper into which a molding material is charged, a cylinder connected to the hopper, a screw inserted into the cylinder, and a tip of the cylinder. The basic configuration is a die. Cylinders are generally roughly divided into two parts: an individual transport section that transports the molding material (resin) supplied from the hopper to the die side for a certain distance as it is (softening) as it is, and a molding material sent from the individual transport section. Is melted, and the melted molding material is sent to a die. Further, the melt transport section is a melting section (also referred to as a compression section) of a region where the molding material sent from the solid transport section is melted (a region where melting is started to complete melting).
And a metering section for adjusting (measuring) the amount of the completely melted molding material sent to the die. Since the metering of the completely melted molding material is performed at the last several pitches of the screw, a portion corresponding to the last several pitches of the screw having a cylinder is usually called a metering section.

In the extrusion molding of synthetic polymer materials, the temperature of the extruder is generally of a so-called "incremental-inclined" variation. This "incremental slope type" change form
The temperature is gradually increased from the upstream side to the downstream side of the extruder, that is, from the material supply port of the cylinder to the die. Also in extrusion molding of a so-called urethane rubber, a polyurethane-based thermoplastic elastomer (hereinafter, also simply referred to as a polyurethane elastomer), usually, the temperature of the kneading machine is set to such an “increased gradient” variation. For example, in the case of a polyurethane elastomer (Tecoflex EG-100A (trade name), Tecoflex EG-65D (trade name)) manufactured by Thermedics, USA, Tecofl
In ex EG-100A, the individual transport section of the cylinder is 163 ± 5
° C, 177 ± 5 ° C for the measuring part of the cylinder and 18 for the dice
It can be set to 2 ± 5 ° C with Tecoflex EG-65D
It is recommended that the individual transport section of the cylinder be set at 190 ± 5 ° C., the metering section of the cylinder be set at 199 ± 5 ° C., and the dies be set at 204 ± 5 ° C.

[0004] When the above-mentioned polyurethane-based thermoplastic elastomer is molded into a tube with the extruder temperature set to the recommended "increased gradient type", the heat shrinkage of the tube is 0.1%.
5 to 3%, and a tube which hardly shrinks by heating at room temperature after molding can be obtained. In addition, the tubes thus obtained have small dimensional variations.
However, when a polyurethane-based thermoplastic elastomer that exhibits a glassy state at room temperature and has shape memory properties is formed into a tube by using the same “increased inclination type” as described above, only a tube having a heat shrinkage of 5 to 10% is obtained. Did not. In addition, when the temperature of the entire extruder was shifted to a higher temperature side in order to improve the moldability, the melt viscosity in the die became too low, and the dimensional stability of the molded product was greatly reduced. .

[0005] The above "normal temperature" means a temperature range of 20 to 30 ° C, and in the following text, "normal temperature" means the same temperature range. The “heat shrinkage of the tube” is a rate of change in the length of the tube before and after the heat treatment of a test piece of a 10 cm long tube at 80 ° C. for 2 hours, that is, the formula: heat shrinkage (%) =
[[(Length before processing) − (length after processing)] / (length before processing)] × 100, and the “heat shrinkage rate of tube” in the following text. Means a value measured in the same manner. In addition, the test piece was 80
The heat treatment for 2 hours is a treatment in which a test piece is heated and left in a thermostat.

[0006]

As described above, when a polyurethane thermoplastic elastomer having a glassy state at room temperature and having shape memory properties is formed into a tube by extrusion, the heat shrinkage and dimensional stability of the tube are increased. Have a big problem in that. In addition, cannula indwelling needle and IH
Medical small-diameter tube (outer diameter:
(0.7-2.0 mm).
Extremely strict product characteristics of less than 5% and dimensional stability of ± 0.05 mm or less are required. Such medical small-diameter tubes are made of polyurethane thermoplastic elastomer tubes from the viewpoint of antithrombotic properties and flexibility. In particular, tubes made of polyurethane thermoplastic elastomer having shape memory properties are becoming mainstream. However, as described above, the heat-shrinkage rate of a tube obtained by molding a polyurethane-based thermoplastic elastomer exhibiting a glassy state at ordinary temperature with an extruder in which the form of temperature change is the above-described “increased slope type” is 5 to 5. It shows 10% and cannot be used as it is as a medical thin tube. Accordingly, the present applicant has filed Japanese Patent Application Nos. 10-241859 and 10-241.
No. 860 proposes a method of reducing the heat shrinkage of a thermoplastic elastomer tube by holding the thermoplastic elastomer tube in a straight line and annealing the tube. Using this method, it is possible to reduce the heat shrinkage of the tube to less than 0.5%. However, such a method for reducing the heat shrinkage of the tube is to rewind the tube formed by extrusion and wound on a reel into a frame that can be held linearly for annealing, and to cut the tube into a short length after annealing. ,
Usually, tubes are shipped short. Therefore, a short tube is assembled in a required form at the site of use. However, since this assembling operation is complicated, there is a demand from the site of use (user) to supply the tube in a reel wound form.

In view of the above circumstances, the present invention provides a tube made of a polyurethane-based thermoplastic elastomer which exhibits a glassy state at room temperature and has a shape memory property. An object of the present invention is to provide a method for producing a polyurethane-based thermoplastic elastomer tube which can be produced with good efficiency.

In addition, a tube having an extremely small heat shrinkage (heat shrinkage of less than 0.5%) required for a small-diameter tube for medical use can be obtained in the form of a reel-wound product. An object of the present invention is to provide a method for producing a polyurethane-based thermoplastic elastomer tube.

[0009]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that polyurethane-based thermoplastic elastomers are generally easily foamed and easily decomposed. Has been considered common practice not to be higher than 220 ° C., but exhibits a glassy state at normal temperature,
The temperature of the cylinder is gradually increased from the vicinity of the material supply port to the tip of the die side, and the temperature of the die is 230 ° C.
As described above, and when molded into a tube with an extruder in which the temperature of the die is set lower than the temperature of the die-side tip of the cylinder, the shrinkage stress during molding is reduced, and the heat shrinkage of the tube can be reduced. If the tube thus formed is allowed to stand for a predetermined time at room temperature and normal humidity with the reel wound as a reel and then heat-treated at a temperature equal to or higher than the glass transition temperature of the elastomer, the heat shrinkage of the tube can be further reduced. And completed the present invention. In addition,
The above “normal humidity” means a humidity of 45 to 65% RH,
In the following text, "normal humidity" means the same humidity.

That is, the present invention has the following features. (1) The temperature of the cylinder is gradually increased from the vicinity of the material supply port to the die-side tip, and the temperature of the die-side tip is increased to 230 ° C. or more. ,And,
A method for producing a polyurethane-based thermoplastic elastomer tube, wherein the tube is formed by an extruder in which a temperature of a die is set lower than a temperature of a tip portion on a die side of the cylinder. (2) Further, the formed tube is wound on a reel to form a reel wound body.
The method for producing a polyurethane-based thermoplastic elastomer tube according to the above (1), wherein the tube is left at room temperature for 48 hours or more and then heat-treated at a temperature equal to or higher than the glass transition temperature of the polyurethane-based thermoplastic elastomer. (3) The method for producing a polyurethane-based thermoplastic elastomer tube according to (2), wherein the heat treatment temperature is 80 to 100 ° C. (4) The above (2) or (3), wherein the tube is wound on a reel with a tension of 100 to 350 g / mm ^2.
A method for producing the polyurethane-based thermoplastic elastomer tube according to the above. (5) The tube is wound on a reel at room temperature or at a temperature lower by at least 10 ° C. than the glass transition temperature of the polyurethane thermoplastic elastomer.
(4) The method for producing a polyurethane-based thermoplastic elastomer tube according to any of (4).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a polyurethane thermoplastic elastomer tube of the present invention, a polyurethane thermoplastic elastomer exhibiting a glassy state at room temperature and having a shape memory property is prepared by dicing a cylinder temperature from a vicinity of a material supply port into a die. It is necessary to gradually raise the temperature to 230 ° C. or more at the die-side tip, and to form the tube using an extruder in which the temperature of the die is set lower than the temperature of the die-side tip of the cylinder. Further, after leaving the wound body on a reel of the above-formed tube for 48 hours or more at normal temperature and normal humidity for the purpose of further reducing the heat shrinkage of the tube, the glass transition of the polyurethane-based thermoplastic elastomer is performed. The heat treatment is performed at a temperature lower than the temperature.

In the following description, the temperature of the cylinder gradually rises from the vicinity of the material supply port to the tip of the die, reaches 230 ° C. or more at the tip of the die, and the temperature of the die rises at the tip of the die of the cylinder. The form of the temperature change of the extruder at a temperature lower than the temperature will be referred to as a “mountain type” corresponding to the conventional “increased inclination type”.

In the present invention, first, the extruder is made to have a "mountain-shaped" temperature change form, and a polyurethane thermoplastic having a glassy state at room temperature and a shape memory property is formed into a tube. This makes it possible to suppress the shrinkage stress due to molding as compared with a case where the conventional extruder is formed by changing the temperature change form to “increased inclination type”, and to reduce the heat shrinkage to about 0.5 to 3%. Can be obtained.

As described above, the cylinder of the extruder is divided into a solid transporting section and a melt transporting section (melting section + measurement section) according to its role, and each section is usually divided into a plurality of small sections. The temperature of the cylinder is controlled so that the temperature of the cylinder can be finely controlled. In the present invention, the temperature rise from the vicinity of the material supply port of the cylinder to the tip of the die may be increased incline or stepwise. The vicinity of the material supply port of the cylinder is preferably set in the range of 170 to 220 ° C., particularly preferably 190 to 220 ° C.
It is in the range of 00 ° C. If the temperature is lower than 170 ° C, kneading of the resin may be insufficient.
There is a possibility that the bite of the resin may be deteriorated and pulsation may occur.
It is preferable that the temperature at the final end of the solid transport section (the start end of the melt transport section (melting section)) be set in the range of 190 to 230 ° C. In addition, the temperature difference between the final end of the solid transport section (start end of the melt transport section (melting section)) and the vicinity of the material supply port is 1
0-30 ° C is preferred.

As described above, the measuring section of the cylinder
The portion corresponding to the final several pitches of the screw for adjusting (measuring) the amount of the completely melted material just before being sent out to the die in the melt transporting section. "Means the temperature at the end of the metering section. The temperature of the tip of the cylinder on the die side, that is, the temperature of the final end of the measuring section is 230 ° C.
The temperature is preferably set in the range of 245 ° C, particularly preferably in the range of 235 to 240 ° C. If the temperature is higher than 245 ° C., foaming or burns may occur, and the melt-kneading may be too low to draw. If the temperature is lower than 230 ° C., the heat shrinkage may be deteriorated. The temperature at the beginning of the metering section is 22
It is preferable to set the temperature in the range of 0 to 235 ° C. Further, the temperature difference between the start end of the weighing section and the final end of the weighing section is 0.
It is preferably from 10 to 10 ° C.

The temperature of the die is preferably set in the range of 180 to 220 ° C., particularly preferably 190 to 210 ° C.
It is in the range of ° C. If the temperature is lower than 180 ° C., the heat shrinkage may be deteriorated. If the temperature is higher than 220 ° C., foaming or burnt may occur, or the melt viscosity may be too low to draw.

The tube formed by the extruder is usually taken up on a reel (reel for taking up a molded product) by a tube take-up machine installed at a stage subsequent to the extruder, and is obtained as a reel wound body. . Further, the tube obtained as such a reeled body is usually further wound on a product shipping reel and shipped.

The thus obtained tube has a heat shrinkage of about 0.5 to 3% as described above. However, since the tube is in a glass state at normal temperature, it is left at normal temperature and normal humidity. However, relaxation of shrinkage stress does not occur unlike a tube obtained by molding an elastomer having a glass transition temperature lower than room temperature. Therefore, for example, in order to obtain a tube that requires a heat shrinkage of less than 0.5%, such as a small-diameter tube for medical use, it is necessary to further heat-treat the tube at a temperature equal to or higher than the glass transition temperature. Such heat treatment may be performed on the tube as it is wound on a reel, so that the heat shrinkage of the tube can be reduced to less than 0.5%.

The heat treatment at a temperature equal to or higher than the glass transition temperature must be performed after the tube is left at room temperature and normal humidity for 2 days (48 hours) after molding. This is because the tube immediately after extrusion is extremely unstable molecularly, and the inherent adhesiveness of polyurethane is particularly prominent, and the tubes that are wound around the reel and adhere to each other cannot be pulled out from the reel. If the tube is forcibly pulled out, the surface of the tube may be scratched or cracked. The above-mentioned problem is caused by the fact that hydrophilic groups in the molecules of the elastomer gather on the metal surface of the resin flow path of the extruder during molding, and as a result, many hydrophilic groups are present on the surface of the tube immediately after molding, and the adhesion of the tube is increased. Is considered
By leaving it for more than 2 days (48 hours) under normal temperature and normal humidity,
During this time, the hydrophilic group that has been biased toward the tube surface diffuses throughout the tube, and the adhesiveness of the tube is reduced.

The heat treatment at a temperature equal to or higher than the glass transition temperature is preferably performed in the range of 80 to 100 ° C., particularly preferably 80 to 90 ° C. Since the molecular form of the elastomer immediately after extrusion molding does not form a pseudo crystal and is very unstable, it is difficult to exhibit unique material properties. By performing the above-mentioned standing treatment under normal temperature and normal humidity for 2 days (48 hours) or more, the molecular form tends to stabilize, and at this time, hydrogen bonding between the hydrophilic groups of the hard segment and the soft segment proceeds, Since the stabilization of the molecular form here is merely the stabilization by molecular motion below the glass transition temperature, the intrinsic material properties are hardly sufficiently exhibited. Hydrogen bonds between the hydrophilic groups of the hard segment and the soft segment are converted into hydrogen bonds of the hydrophilic groups between the hard segments by heat treatment at a temperature higher than the glass transition temperature. And inherent material properties are developed. In particular, by performing the heat treatment at a temperature of 80 to 100 ° C., the molecular stability is further improved, and the inherent material characteristics are more remarkably exhibited.

In the polyurethane-based thermoplastic elastomer, the soft segment has a softening temperature of about 20 to 80 ° C.
Have the property of shape memory. That is, since the melting temperature of the hard segment is higher than the soft segment and there is an appropriate temperature difference, molding is performed at a temperature higher than the melting temperature of the hard segment. Even if it is heated and forcibly deformed by applying force to be solidified into another shape, it returns to the original shape when heated again to a temperature at which only the soft segment is melted. It is generally said that such a shape memory polymer made of a polyurethane-based thermoplastic elastomer is preferably heat-treated at a temperature in the range of 80 to 100 ° C. in order to form a molecular structure that causes a shape memory effect.

In the present invention, if the above heat treatment at 80 to 100 ° C. is performed to reduce the heat shrinkage of the tube after molding, the shape at that time is stored as a basic shape.
Care must be taken in the shape of the tube before heat treatment. The formed tube is once wound on a reel as described above, but the winding tension at that time may cause the tube to be flattened. If flattening occurs, the shape is memorized by heat treatment, which is not preferable. Further, as described above, the tube wound on the reel after molding is re-wound to a reel for shipping the product. At this time, the tube may be flattened similarly to the above.
Therefore, from the viewpoint of preventing flattening, it is preferable to wind the tube around a reel (a reel for taking up a molded product, a reel for shipping a product) with as low a tension as possible as long as it is not irregularly wound. The tension is preferably about 350 to 350 g / mm ² , more preferably about 200 to 250 g / mm ² . In addition, since the flattening of the tube may be caused by insufficient cooling, the temperature at the time of winding may be room temperature from the viewpoint of preventing the flattening, but the winding at a temperature lower than the glass transition temperature of the elastomer by 10 ° C. or more is possible. It is preferable to take. In addition, the flattening of the tube here is generally defined as the “flattening rate” obtained by dividing the “difference between the long outside diameter and the short outside diameter” of the tube by the “average value of the long outside diameter and the short outside diameter”. Usually, when the “flattening ratio” is larger than 4%, flattening is remarkable.

When the reeled body of the tube is heat-treated at a temperature equal to or higher than the glass transition temperature, at least one end of the tube is preferably kept open. Thereby, the dimensional change of the tube due to the expansion of the air in the tube can be suppressed. In addition, as a method of keeping at least one end of the tube open, a method of inserting a hard tube into the end of the wound tube can be used.

The polyurethane-based thermoplastic elastomer having shape memory properties used in the present invention is obtained by using a long-chain polyol, short-chain glycol, diisocyanate, or the like as a raw material, through a urethane bond in a molecule by a polyaddition reaction. The resulting polymer is obtained by forming a soft segment with a long-chain polyol and a diisocyanate, and forming a hard segment with a short-chain glycol and a diisocyanate. The glass transition temperature is not particularly limited as long as it exhibits a glassy state at normal temperature, but the glass transition temperature is usually 25 to 60 ° C, preferably 35 to 50 ° C.

The isocyanate component used for producing the polyurethane is not particularly limited as long as it is generally used for polyurethanes. For example, 2,4- or 2,6-tolylene diisocyanate, 4,4 ' Diphenylmethane diisocyanate, hexamethylene diisocyanate, m- or p-phenylene diisocyanate, isophorone diisocyanate and crude components or mixtures thereof. As the isocyanate component, 4,4′-diphenylmethane diisocyanate is particularly preferred.

As the polyol component, one having at least two or more active hydrogens in one molecule, particularly a hydroxyl group is used. For example, polyhydric alcohols such as diols and triols, aliphatic amines, aromatic amines and the like are used. Agent, a polyoxyalkylene polyol produced by adding an alkylene oxide thereto, a polyester polyol produced by condensing an acid and an alcohol, or polytetramethylene glycol, polybutadiene polyol, polypropylene glycol, 1,4-butane glycol adipate , Polytetramethylene glycol, polyethylene glycol, bisphenol-A + propylene oxide, particularly preferably bisphenol-A + propylene oxide.

As the chain extender, ethylene glycol,
Glycols such as 1,4-butanediol and diethylene glycol, amines such as diethanolamine, triethanolamine, tolylenediamine and hexamethylenediamine, TDI (tolylenediisocyanate) adduct of trimethylolpropane, triphenylmethane triisocyanate, bis ( 2-hydroxyethyl) hydroquinone, bisphenol-A + ethylene oxide,
Examples include polyisocyanates such as bisphenol-A + propylene oxide. As the chain extender, 1,4-butanediol is particularly preferred.

The molar ratio of the isocyanate component, the chain extender and the polyol component is from 1.5 to 3: 0.5 to
2: 1, preferably 1.8-2.5: 0.8-1.5:
1, more preferably 1.8 to 2.1: 0.8 to 1.1:
It is one.

Further, a catalyst is used if necessary to accelerate the reaction. Examples of the catalyst include tertiary amines such as triethylamine, tetramethylhexamethylenediamine and tolylenediamine, and metal catalysts represented by tin catalysts such as stannas octoate, stannas oleate and dibutyltin dilaurate. Are used alone or in combination.

Urethane is synthesized using the above isocyanate, polyol, chain extender and, if necessary, a catalyst. As the synthesizing method, for example, a method disclosed in JP-A-61-293214 can be adopted.

As the extruder, a general single-screw extruder or a twin-screw extruder is used. As the twin-screw extruder, any of a co-directional twin-screw extruder and a bi-directional twin-screw extruder can be used. The L / D, the number of revolutions, and the like are not particularly limited, but the L / D is usually 20 to 28,
Preferably 26 to 28, rotation speed is usually 5 to 20 rpm,
Preferably it is 10 to 15 rpm.

The method for producing tubes of the present invention can be applied to methods for producing tubes having various outer diameters.
Suitable for 5mm tube, outer diameter 0.5 ~ 2mm
It is particularly suitable for medical tubes having a small diameter.

[0033]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

Experimental Example 1 (Example 1, Comparative Examples 1 and 2)
Diary MM451 manufactured by Mitsubishi Heavy Industries, Ltd. as a polyurethane-based thermoplastic elastomer having shape memory properties.
0M (glass transition temperature: 45 ° C.).

Single screw extruder (L / D: 25, number of rotations: 10)
rpm), the temperature of the extruder was set as shown in Table 1 below, and the above elastomer was formed into a tube having an outer diameter of 0.7 mm and wound on a reel by a winder. Then, the thermal shrinkage and the dimensional variation of the obtained tube were measured. Note that the dimensional variation is a variation in the outer diameter of the tube. The tube was formed (manufactured) three times for each condition, and the average value of the heat shrinkage was calculated. The results are shown in Table 1 below.

[0036]

[Table 1]

As can be seen from Table 1, in Comparative Examples 1 and 2 in which the temperature change of the extruder was changed to the conventional "incremental inclined type" to form the tubes, the heat shrinkage of the tubes was 5 to 10%, respectively. In Comparative Example 2, the dimensional variation was not within ± 0.05 mm, and was ± 0.1 m.
m. On the other hand, in Example 1 in which the shape of the temperature change of the extruder was changed to the “mountain shape” of the present invention to form the tube, the heat shrinkage of the tube was 0.5 to 3%,
The dimensional variation was within ± 0.05 mm.

Experimental Example 2 (Examples 2 to 4) A tube formed under the same extrusion conditions as in Example 1 was wound on a reel with a different winding tension.
Each reel was heat-treated, and the (heat-shrinkage rate, flatness) of the tube after the heat treatment was measured. The heat treatment was performed at 80 ° C. for 2 hours after leaving the reel wound body at room temperature and normal humidity for 48 hours or more. In addition, three reels were prepared for each winding tension, and the average value of the thermal shrinkage was obtained. The results are shown in Table 2 below.

[0039]

[Table 2]

After standing for 48 hours or more under normal temperature and humidity, 80
It was found that heat treatment at 2 ° C. for 2 hours reduced the heat shrinkage of the tube to less than 0.5%, and that the heat shrinkage and flatness of the tube could be reduced by reducing the winding tension of the tube. .

Experimental Example 3 (Examples 5 to 8) Tubes having different outer diameters were molded under the same extrusion conditions as in Example 1, and the tube characteristics were examined. The winding tension of the tube on the reel is substantially the same (220 g / mm
² ) and heat treatment was applied to each of the reeled bodies, and the (heat shrinkage, flatness) of the heat-treated tube was measured. The heat treatment was performed at 80 ° C. for 2 hours after leaving the reel wound body at room temperature and normal humidity for 48 hours or more. In addition, three reel windings were prepared for each tube of each outer diameter, and the average value of the thermal shrinkage was obtained. The results are shown in Table 3 below.
The table also shows Example 3 in Experimental Example 2 above.

[0042]

[Table 3]

As shown in Table 3, even if the outer diameter of the tube is different,
It can be seen that the heat shrinkage decreases to less than 0.5% by heat treatment at 80 ° C. for 2 hours after standing for 48 hours or more under normal humidity.

[0044]

As is apparent from the above description, according to the present invention, a polyurethane-based thermoplastic elastomer exhibiting a glassy state at room temperature and having a shape memory property is obtained by changing the temperature of the cylinder from the vicinity of the material supply port to the die side. Gradually raise over the tip, make the tip on the die side 230 ° C or higher,
In addition, by using an extruder in which the temperature of the die is set lower than the temperature of the die-side tip of the cylinder, the heat shrinkage, which could not be obtained conventionally, has been reduced to 0.5 to 3% by forming into a tube. The tube can be manufactured to a desired size with high accuracy. Further, in particular, after the molded tube is left under normal temperature and normal humidity for 48 hours or more, the tube is heat-treated at a temperature equal to or higher than the glass transition temperature of the elastomer, thereby further reducing the heat shrinkage of the tube to less than 0.5%. be able to. Since such heat treatment can be performed with the tube being wound on a reel, the working efficiency is high. Also, since the tube with reduced heat shrinkage can be obtained in the form of a reel wound around a reel, the product can be shipped as a reel wound,
The workability of handling the tube on the user side is improved.

Continued on front page F term (reference) 4F207 AA31 AA45 AE01 AG08 AR06 KA01 KA17 KK43 KM16 KW21 KW33 4J034 CA04 CA05 CA13 CA15 CA17 CB03 CB04 CB07 CB08 CC03 CC08 CC12 CC62 CC67 CD01 CD04 DA01 DB03 DG16 DG20 DG16 DG20 GA05 GA33 HA01 HA02 HA07 HA08 HC03 HC12 HC17 HC22 HC46 HC52 HC61 HC64 HC65 HC67 HC71 HC73 KA01 KB02 KC17 KD02 KD12 KE02 QB15 QC07

Claims (5)

[Claims] 1. The temperature of a cylinder of a polyurethane-based thermoplastic elastomer having a glassy state at room temperature and having a shape memory property is gradually increased from the vicinity of a material supply port to a die-side tip, and the die-side tip is 230 ° C. A method for producing a polyurethane-based thermoplastic elastomer tube, wherein the tube is molded by an extruder in which the temperature of the die is set lower than the temperature of the die-side tip of the cylinder. 2. The molded tube is wound on a reel to form a reel wound body. The reel wound body of the tube is allowed to stand at room temperature and normal humidity for 48 hours or more, and then a glass transition temperature of the polyurethane thermoplastic elastomer is obtained. The method for producing a polyurethane thermoplastic elastomer tube according to claim 1, wherein the heat treatment is performed at the above temperature. 3. The method for producing a polyurethane-based thermoplastic elastomer tube according to claim 2, wherein the heat treatment temperature is 80 to 100 ° C. 4. A tube having a tension of 100 to 350 g / mm.
^The method for producing a polyurethane-based thermoplastic elastomer tube according to claim 2 or 3, wherein the tube is wound on a reel in (2). 5. The polyurethane system according to claim 2, wherein the tube is wound around a reel at room temperature or at a temperature lower by at least 10 ° C. than the glass transition temperature of the polyurethane thermoplastic elastomer. A method for producing a thermoplastic elastomer tube.