JPH07100882B2 - Hollow fiber for heat exchanger and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a hollow fiber for heat exchanger comprising an organic polymer,
Particularly, the present invention relates to a hollow fiber for a heat exchanger which is useful when used as a heat exchanger for an artificial lung or the like.

<Prior Art> An artificial lung is used for an assisted cardiopulmonary device for open heart surgery and an alternative device for a lung with reduced function, and it is necessary to control the temperature of blood taken out of the body during surgery. A heat exchanger is indispensable as a means for this, and the details thereof are described in, for example, Japanese Patent Publication No. 55-2982 and Japanese Patent Laid-Open No. 57-39854.

<Problems to be solved by the invention> Conventionally, as a material of a pipe of a heat exchanger that has been used as an auxiliary device of an artificial lung, a stainless steel pipe having good heat conductivity and good heat resistance is often used. There are problems such as the method of sealing the end face when assembling into a heat exchanger, the destruction of particulate matter in blood by the edge of the end face, and the reactivity with blood components having a complicated composition.

Hollow fibers for heat exchangers made of organic polymers are sufficient to solve the problems of the above-mentioned conventional materials and are sufficient as pipes for heat exchangers. In some cases there are some problems. That is, when these pipes are incorporated into a heat exchanger, it is generally necessary to arrange the pipes and partition them so as not to mix the substances on the heat-supply side and the heat-absorption side. As this means, potting technology using an organic resin is used. In many cases, the adhesion of the organic polymer to the organic resin is not good.

<Means for Solving Problems> Therefore, the inventors of the present invention have made diligent studies to solve the above problems of the heat exchanger hollow fiber made of an organic polymer, and as a result, the surface layer portion of the heat exchanger hollow fiber. The present invention has been completed by discovering that the adhesiveness with an organic resin used for potting is dramatically improved by providing microscopic holes in the.

That is, the gist of the present invention is that the outer layer and the inner layer are made of different kinds or the same kind of organic polymer having different melt viscosity index (MI value), and the outer layer having fine pores and the inner layer having no continuous through-hole are bonded. A hollow fiber for a heat exchanger obtained by composite melt spinning, characterized in that the sum of both thicknesses is 50-2000μ with an inner diameter of 2-500μ. Using a hollow fiber manufacturing nozzle having two annular discharge ports arranged in a circular pattern, the same type of organic polymer having a different or different melt viscosity index is separately supplied to each discharge port to perform melt composite spinning. The method is characterized in that a hollow fiber having two layers is obtained, and the hollow fiber is subjected to an annealing treatment as it is, followed by stretching to produce a large number of micropores only in the outer layer, and then heat setting. Of different types or of the same type with different melt viscosity indexes Consists of polymer, and the inner layer a through hole is not present is in the manufacturing method of the heat exchanger hollow fibers bonded continuous outer layer having fine pores.

The organic polymer used in the present invention is polyethylene, polypropylene, poly-3-methylbutene-1, poly-4-methylpentene-1, polyvinylidene fluoride, polyethylene terephthalate, polytetramethylene terephthalate,
Polyhexamethylene adipate, polycaprolactam,
Examples thereof include polyoxymethylene or crystalline polymers containing these as a main component, silicon, urethane, ethylene vinyl acetate copolymer, ethylene-piel alcohol copolymer, ethylene vinyl chloride copolymer and the like.

The form of the hollow fiber for the heat exchanger of the present invention may be any form, but considering that it is used for heat exchange applications, it is preferable that the hollow fiber has sufficient mechanical strength, and therefore the tube wall thickness is 2 to 500 μm. It is particularly preferable that the inner diameter is about 50 to 2000 μm.

The heat exchanger hollow fiber of the present invention uses a hollow fiber manufacturing nozzle having two annular discharge ports arranged concentrically, and the same type of organic polymer having different or different MI values is provided at each discharge port. Separately supplied and melt-spun to obtain a hollow fiber having two layers, the hollow fiber as it is or after an annealing treatment, stretched to produce a large number of micropores only in the outer layer, After that, it is obtained by heat setting.

The MI value of the organic polymer constituting the outer layer used in the present invention is preferably in the range of 0.1 to 1.0. MI value is AS
It is a value measured by TM D-1238, and is most preferably in the range of 1 to 6. This range is a desirable range for stably producing a hollow fiber having stable micropores in the outer layer, and in the region of 1.0 or less, the melting temperature is too high and stable spinning is difficult to perform, and 10 This is because in the range of the MI value above, the expression of micropores becomes insufficient when the film is made porous by stretching.

The MI value of the organic polymer forming the inner layer is preferably in the range of 1.5 to 50. When MI is less than 15, through holes are likely to be formed in the inner layer, and when it exceeds 50, the melt viscosity becomes too low, which makes stable spinning difficult to perform. When different kinds of polymers are used, those which easily generate fine pores may be arranged in the outer layer under the same stretching conditions.

The spinning temperature of the organic polymer may be any temperature as long as the organic polymer can be extruded from the annular nozzle, but if the melting temperature is too high, the melt viscosity will be too low to make stable spinning difficult. Therefore, it is preferably in the range of melting point to (melting point + 80 ° C.).

In the region where the spinning draft is 30 or less, the orientation of the hollow fiber becomes low, a sufficient elongation cannot be obtained during the subsequent stretching, and the stretching amount necessary to open the micropores cannot be ensured. The above is desirable.

The annealing temperature may be any temperature as long as it stabilizes the internal crystal structure, but the melting point is the temperature at which the crystal structure is stabilized more quickly without breaking the morphology.
The range of (melting point −100 ° C.) is preferable.

Stretching is a step of expressing micropores in the outer layer portion of the hollow fiber after heat treatment, and in order to express the micropores, the crystal itself is not deformed and is stretched at a temperature at which the crystal interface peels off. There is a need. For that purpose, it is preferable to stretch at a relatively low temperature of (melting point −100 ° C.) or lower.

The heat setting is a step of expanding and stabilizing the micropores generated by cold stretching depending on the case, and it is necessary to stretch at a temperature at which the structure itself is less deformed and the micropore structure is stable. For that purpose, the range of melting point to (melting point −60 ° C.) is preferable.

Since the hollow fiber for heat exchanger obtained by the present invention has micropores in the tube wall portion, the adhesiveness with the organic resin used in the potting process performed when assembling into the heat exchanger is not only the adhesive force at the interface but also the organic force. The resin can be dramatically improved by a mechanical binding force caused by the resin penetrating into the inside of the micropores and solidifying, and when used in a heat exchanger, its reliability can be increased. Furthermore, since the hollow fiber for heat exchanger obtained by the present invention is shaped by the above-described drawing method, it has good orientation and excellent mechanical strength.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 Polyethylene having a density of 0.968 melt index 5.5 (Hi-Zex 2200J manufactured by Mitsui Petrochemical Co., Ltd.) and polyethylene having a density of 0.92 melt index 2 (Ultzex 3021F manufactured by Mitsui Petrochemical Co., Ltd.) are concentrically arranged in two annular shapes. Using a hollow fiber manufacturing nozzle having a discharge port of, the discharge temperature of the high-density polyethylene from the outer discharge port is 170 ° C., the discharge linear velocity is 8 cm / min, and the low-density polyethylene is discharged from the inner discharge port of 170 ° C. , Discharge linear velocity 2cm / m
It was extruded and wound at a winding speed of 400 cm / min under the condition of in.
At this time, the spinning draft of high-density polyethylene was 5000 and the spinning draft of low-density polyethylene was 20000.

The unstretched hollow fiber obtained has an inner diameter of 300μ, a high-density polyethylene layer thickness of 60μ, and a low-density polyethylene layer thickness of 6μ.
It was μ. This unstretched hollow fiber was passed through a roller heated at 115 ° C. under a fixed length and annealed for 140 seconds. Subsequently, it was stretched 40% between rollers kept at 20 ° C, further stretched 160% at 105 ° C, and heat set under a fixed length in a box heated to 115 ° C to obtain a hollow fiber for heat exchanger. It was

The resulting hollow fiber for heat exchanger has a tube wall thickness of 50μ and an inner diameter of
It was 240μ. The hollow fiber for heat exchanger was potted with a urethane adhesive (C-4403 / N-4221 manufactured by Nippon Polyurethane Co., Ltd.), cured at room temperature for 1 week, and then the potting portion was cut. As a result of visual observation of the cut surface with an optical microscope, no hollow fiber was peeled from the urethane resin.

Comparative Example 1 The hollow fiber after annealing in Example 1 was potted with a urethane adhesive in the same manner as in Example 1, cured for 1 week, and then the potting portion was cut. As a result of observing the cut surface with an optical microscope, almost all the hollow fibers were separated from the urethane resin.

Example 2 Polyethylene having a density of 0.968 and a melt index of 5.5 (HIZEX 2200J manufactured by Mitsui Petrochemical Co., Ltd.) and a density of 0.91
A polypropylene having a melt index of 0 and a melt index of 15 (UBE Polypro J-115G, Ube Industries, Ltd.) was used to form a hollow fiber manufacturing nozzle having two annular discharge ports concentrically arranged. Density polyethylene discharge temperature 190 ℃, discharge linear velocity 8cm / min, the polypropylene discharge temperature 190 ℃, discharge linear velocity 0.7cm / m
It was wound at an extrusion winding speed of 200 m / min under the in condition. At this time, the spinning draft of high-density polyethylene was 2500 and the spinning draft of polypropylene was 30,000.

The unstretched hollow fiber obtained had an inner diameter of 350 μm, a high-density polyethylene layer thickness of 35 μm, and a polypropylene layer thickness of 5 μm. This unstretched hollow fiber was passed through a roller heated at 115 ° C. under a fixed length and annealed for 140 seconds. Subsequently, it was stretched 40% between rollers kept at 20 ° C, further stretched 160% at 105 ° C, and heat set under a fixed length in a box heated to 115 ° C to obtain a hollow fiber for heat exchanger. It was

The resulting hollow fiber for heat exchanger has a tube wall thickness of 33μ and an inner diameter of
It was 340μ. The hollow fiber for heat exchanger was potted with a urethane adhesive (C-4403 / N-4221 manufactured by Nippon Polyurethane Co., Ltd.), cured at room temperature for 1 week, and then the potting portion was cut. As a result of observing the cut surface with an optical microscope, no hollow fiber was peeled from the urethane resin.

Comparative Example 2 The hollow fiber after annealing in Example 2 was potted with a urethane adhesive in the same manner as in Example 2, cured for 1 week, and then the potted portion was cut. As a result of observing the cut surface with an optical microscope, almost all the hollow fibers were separated from the urethane resin.

Example 3 Polyoxymethylene having a melt index of 3.6 (Tenac 3010 manufactured by Asahi Kasei Corporation) and an ethylene vinyl acetate copolymer having a density of 0.925 melt index 30 (NUO ethylene copolymer DQDJ-3868 manufactured by Nippon Unicar Co., Ltd.) were concentrically formed. Using a hollow fiber membrane-forming nozzle having two annular ejection ports arranged, the polyoxymethylene ejection temperature from the outer ejection port is 180 ° C., the ejection linear velocity is 6 cm / min,
The ethylene vinyl acetate copolymer was extruded from the inner discharge port under the conditions of a discharge temperature of 180 ° C. and a discharge linear velocity of 0.5 cm / min,
It was wound at a winding speed of 200 m / min. At this time, the spinning draft of polyoxymethylene was 3333 and the spinning draft of ethylene-vinyl acetate copolymer was 40,000.

The unstretched hollow fiber obtained had an inner diameter of 300 μ, a polyoxymethylene layer thickness of 30 μ, and an ethylene-vinyl acetate copolymer layer thickness of 4 μ. This unstretched hollow fiber was passed through a roller heated at 115 ° C. under a fixed length and annealed for 140 seconds. Hollow fibers for heat exchangers were then stretched 40% between rollers kept at 30 ° C, further stretched 160% at 110 ° C, and then heat-set under constant length in a box heated to 120 ° C. Got

The resulting hollow fiber for heat exchanger has a tube wall thickness of 30μ and an inner diameter of
It was 292μ. The hollow fiber for heat exchanger was potted with a urethane adhesive (C-4403 / N-4221 manufactured by Nippon Polyurethane Co., Ltd.), cured at room temperature for 1 week, and then the potting portion was cut. As a result of observing the cut surface with an optical microscope, no hollow fiber was peeled from the urethane resin.

Comparative Example 3 The hollow fiber after annealing in Example 3 was potted with a urethane adhesive in the same manner as in Example 3, cured for 1 week, and then the potted portion was cut. As a result of observing the cut surface with an optical microscope, some hollow fibers were peeled from the urethane resin.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location D01F 8/16 F28F 21/06 (56) References JP-A-49-62380 (JP, A) Special features Kosho 62-44046 (JP, B2)

Claims (6)

[Claims] 1. An outer layer and an inner layer are different or have a melt viscosity index (MI
A hollow fiber composed of the same type of organic polymer having different values), in which an outer layer having fine pores and an inner layer having no continuous through holes are joined, and the sum of both thicknesses is 2 to 500 μm,
A hollow fiber for a heat exchanger obtained by composite melt spinning, having an inner diameter of 50 to 2000 μm. 2. A hollow fiber manufacturing nozzle having two concentrically arranged annular discharge ports is used, and different or different organic polymers (having different MI values) of the same type are separately provided at each discharge port. It is supplied and melt-compound-spun to obtain a hollow fiber having two layers, and the hollow fiber is subjected to an annealing treatment as it is, and then stretched to produce a large number of micropores only in the outer layer. A hollow fiber for a heat exchanger, which is composed of organic polymers of different types or of the same type having different melt viscosity indexes characterized by post-heat setting, and in which an outer layer having fine pores and an inner layer having no continuous through holes are joined. Manufacturing method. 3. The melt viscosity index (MI value) of the organic polymer constituting the outer layer of the hollow fiber during spinning is set to 0.1 to 1.0,
The method for producing a hollow fiber for a heat exchanger according to claim 2, characterized in that that of the organic polymer forming the inner layer is set to 1.5 to 50. 4. The spinning temperature is from the melting point of the organic polymer to (melting point + 80).
C.) The method for producing a hollow fiber for a heat exchanger according to claim 2 or 3. 5. The method for producing a hollow fiber for a heat exchanger according to claim 2, 3, or 4, wherein the spinning draft is 3.0 or more. 6. The method for producing a hollow fiber for a heat exchanger according to any one of claims 2 to 5, wherein the heat setting temperature is from melting point to (melting point −60 ° C.).