JPH07208896A - Polyolefin-based heat-exchanging tubular body - Google Patents

Abstract

PURPOSE:To improve adhesive properties between a tubular body and embedding resin, simplify processing and eliminate riskiness of leakage caused on the boundary between the tubular body and the embedding resin, by a method wherein a thin film layer comprising a hydrophilic organic polymer having a polar group is made composite and provided on the outer surface of the tubular body. CONSTITUTION:In a tubular body which is used as a heat transfer tube for a multitubular type heat exchanger and, particularly, in a heat-exchanging tubular body which is used for artificial internal organs such as an artificial lung, etc., a thin film layer comprising a hydrophilic organic polymer having a polar group is made composite on an outer surface of a polyolefin-based heat-exchanging tubular body. By this method, adhesive properties between the tubular body and embedding resin are remarkably improved. Further, a conventional etching treatment and the like are not necessary, and processing is simplified. Such a tubular body has a size that an outer diameter is 150 to 1000mum and a ratio of a wall thickness to the outer diameter is 0.05-0.2, and the thin film layer is provided to have its thickness in a range of 0.01 to 20mum. As the hydrophilic organic polymer, an ethylene/vinyl alcohol-based copolymer having the content of ethylene of 20mol% or more is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubular body for a heat exchanger used as a heat transfer tube for a multitubular heat exchanger, in particular, an artificial organ such as an artificial lung, or the temperature of a liquid material at the time of infusion or blood transfusion. The present invention relates to a novel heat exchange tubular body used as an auxiliary device in the medical field such as regulation.

[0002]

2. Description of the Related Art A heat exchanger is a device for transferring heat from a high temperature fluid to a low temperature fluid, and various types are known, but they have a simple structure and excellent heat transfer efficiency. Therefore, those having a multi-tube structure are often used. For example, an artificial lung is used as an auxiliary cardiopulmonary device in open heart surgery or as an alternative device to a lung with reduced function, but it is necessary to control the temperature of blood taken out of the body during surgery, It is essential to use a heat exchanger together.

[0003]

As a material of the tubular body for a heat exchanger which has been developed so far, a metal having a good thermal conductivity is most effective, and a stainless steel having an excellent corrosion resistance against a fluid for heat exchange. The ones made have been used. However, when installing a stainless steel pipe in a heat exchanger, it is effective to use a potting resin, but since the difference between the hardness of the stainless steel pipe and the hardness of the potting material is too large, it is difficult to process the end surface of the potting portion. There is a problem that a sharp metal edge surface appears on the end surface of the pipe, and the particles are easily broken when processing a liquid containing the particles such as blood cells.

There is also a drawback that the heat transfer area per unit volume is small because a thin pipe cannot be used. Furthermore, there is concern about the reactivity between stainless steel and blood components of complicated composition. The applicant of the present invention has previously proposed a heat exchanger using an organic polymer in a tubular body, which has improved the above-mentioned problems (Japanese Patent Laid-open No. Sho 6-62).
1-83898, JP-A-62-26493).

A heat exchanger using an organic polymer as a tubular body is superior to conventional metallic heat exchangers in that it is easy to manufacture, has corrosion resistance, and is lightweight, and is used in a wide variety of fields. It is considered to be used. However, when a tubular body bundle such as polyethylene or polypropylene is used for the heat exchanger, the affinity with the embedding resin (mainly urethane resin) is lower than the desired degree, and the tubular body and the embedding resin are It has been found that leakage can occur at the interface.

In order to solve this problem, a pretreatment process such as an etching treatment is currently required. On the other hand, when a tubular body made of polyurethane is used as disclosed in Japanese Patent Publication No. 2-504227, the affinity with the urethane resin for embedding becomes good, but the above-mentioned polyolefin-based polymer material is used. It is desired to develop a heat exchanger that is more expensive and more practical in comparison.

Especially when used for artificial lungs, it is absolutely necessary that the heated fluid does not leak into the blood, and the affinity between the tubular body for heat exchange and the resin for implantation is not guaranteed. It can be said that the degree is a serious problem that also affects the life of the patient. In addition, when used for these artificial organs, all of them are disposable, and therefore cheaper materials are desired.

[0008]

The gist of the present invention resides in a polyolefin heat exchange tubular body comprising a composite thin film layer comprising a hydrophilic organic polymer having a polar group on its outer surface.

The tubular body for heat exchange of the present invention is embedded with the tubular body by compounding a thin film layer made of a hydrophilic organic polymer having a polar group on the outer surface of the conventional tubular body for heat exchange of polyolefin. It significantly improves the adhesiveness with the resin for mounting. As a result, the pretreatment process such as the etching process which has been conventionally carried out can be omitted, so that the processing is simplified, and the risk of leakage occurring at the interface between the tubular body and the embedding resin is eliminated.

That is, when this heat exchanger is used for blood treatment or the like, its functionality and reliability are dramatically improved. In addition, since the thickness of the thin film layer is extremely smaller than the wall thickness of the tubular body, a decrease in heat exchange efficiency due to compositing cannot substantially occur. The heat exchange tubular body of the present invention,
The cross-sectional shape does not necessarily have to be circular. For example, by providing fins on the outer side of the tubular body, it is possible to improve the uniform dispersibility of the tubular body bundle or increase the surface area in the cross-sectional direction to further improve the heat exchange efficiency.

In order to improve the heat exchange efficiency of the heat exchanging tubular body of the present invention, the outer diameter of the tubular body used is 150 to 10
The thickness is preferably 00 μm. In order to increase the heat transfer area per unit volume, it is desirable to make the outer diameter of the tubular body as small as possible, but the smaller the diameter, the smaller the inner diameter of the tubular body, and thus the heating medium or the heating medium flowing inside the tubular body. The flow resistance of the heating fluid increases. As described above, when the outer diameter of the tubular body is less than 150 μm, the pressure loss of the fluid flowing inside the tubular body becomes too high, which is not appropriate, and more preferably 300 to 800 μm.

On the other hand, the wall thickness of the tubular body is required to be at least a thickness that does not buckle or burst due to external pressure or internal pressure when the heat exchanger is used. However, as a heat exchanger in the field of use intended by the present invention, 1.5 to 3 which is required when the product is inspected or actually used.
The wall thickness may be such that the tubular body does not buckle or rupture due to the maximum outer pressure of about kg / cm ^{2, and in} order to satisfy such conditions, the wall thickness / outer diameter ratio is 0. 0
It is necessary to be 5 or more. On the other hand, if it exceeds 0.2, the inner diameter becomes excessively thin and the flow resistance of the fluid flowing inside the tubular body becomes high, or the wall thickness becomes excessively thick and the heat transfer resistance of the tubular body becomes too high. Inconvenience occurs.

Further, the thin film layer made of a hydrophilic organic polymer having a polar group may have a minimum necessary thickness for exhibiting adhesiveness with the embedding resin. If it is too thick, not only will the heat exchange efficiency be lowered, but since the hydrophilic organic polymer is more expensive than the polyolefin-based polymer compound, the manufacturing cost will be high. Therefore, the thickness of the thin film layer is 0.01 to 20 μm.
Is preferred.

The material of the tubular body of the present invention may be any organic polymer that can be formed into a tubular body, that is, a hollow tube or a hollow fiber, but is safe when used as a heat exchange means for blood. Polyolefin-based polymer compounds such as polyethylene, polypropylene, and poly-4-methylpentene-1 are preferable as materials that can ensure reliability.

The material of the thin film layer may be any hydrophilic organic polymer which can be composited with the above-mentioned tubular body.
In the field of application intended by the present invention, polyurethane, ethylene / vinyl alcohol copolymer, and polyamide resin having excellent blood compatibility are preferable. In particular, in order to strengthen the adhesiveness between the polyolefin layer and the thin film layer made of a hydrophilic organic polymer, it is most preferable to use an ethylene / vinyl alcohol copolymer.

In this case, as a composition satisfying the adhesiveness to both the polyolefin layer and the embedding resin, the ethylene content is preferably 20 mol% or more, more preferably 20 to 60 mol%. Also, a three-layer structure in which an adhesive polyolefin resin having a functional group that improves the affinity between the polyolefin and the hydrophilic organic polymer is compounded may be used.

The method for producing the tubular body for heat exchange of the present invention is not particularly limited, but the composite spinning method by melt shaping, which has simple steps and low production cost, is most preferable. Specifically, each of the discharge ports of the hollow fiber manufacturing nozzle that melts the melt-shapeable polyolefin-based polymer compound and the hydrophilic organic polymer and has two circular tubular discharge ports arranged concentrically Then, the composite polyolefin-based tubular body of the present invention can be obtained by supplying it to the melt-spun fiber. By adopting the melt shaping method, it is possible to supply a clean tubular body without using a solvent or the like, and it is also possible to freely control the outer diameter by the winding speed.

[0018]

The object of the present invention is to embed a tubular body and a tubular body for embedding by compounding a thin film layer made of a hydrophilic organic polymer having a polar group on the outer surface of a conventional polyolefin type heat exchange tubular body. It is to significantly improve the adhesiveness with the resin. This simplifies the processing because the pretreatment process such as the etching process which has been conventionally performed can be omitted, and the risk of leakage occurring at the interface between the tubular body and the embedding resin is eliminated.

That is, when this heat exchanger is used for blood treatment or the like, the heated fluid does not leak to blood, and the functionality and reliability thereof are dramatically improved. In addition, since the thickness of the thin film layer is extremely smaller than the wall thickness of the tubular body, heat exchange efficiency does not decrease due to compounding, and it can be supplied inexpensively even in the field of use as a disposable product. .

[0020]

EXAMPLES The present invention will now be described in more detail by way of examples. Example 1 Density 0.921 g / cm ³ , MI value 1.5, melting point 134
° C. Low density polyethylene (Showa Denko KK, Shaw Rex M113) and the density 1.14 g / cm ^3, MI value 3.5, melting point 164 ° C., an ethylene content 44 mol% of ethylene / vinyl alcohol copolymer ( Nippon Synthetic Chemical Industry Co., Ltd., Soarnol AT4403) is a hollow fiber manufacturing nozzle having two circular tubular discharge ports arranged concentrically, and a low-density polyethylene discharge amount of 13.0 g from the inside discharge port. / Min, ethylene from the outer outlet /
The vinyl alcohol copolymer was discharged at a discharge rate of 2.0 g / min, and the discharge temperature was 200 ° C. and the winding speed was 20.
Winding up at 0m / min, outer diameter 450μm, wall thickness 65μ
m, and a thin film layer having a thickness of 10 μm was obtained.

A module was prepared by filling 200 pipes into a polycarbonate pipe so as to have a filling density of 40%, and adhering both ends of the pipes with a polyurethane resin with a thickness of 15 mm while keeping both ends open. did. Using this module, an adhesion durability test was conducted at 50 ° C x 3.
When it was carried out in a cycle of 5 kg / cm ² × 10 seconds (ON → OFF), no leakage was found in the potting portion of the tubular body even after repeated up to 20000 times.

Comparative Example 1 Low density polyethylene (Showa Denko KK, Shorex M113) having a density of 0.921 g / cm ³ , an MI value of 1.5 and a melting point of 134 ° C. used in Example 1 was manufactured as a hollow fiber. Was discharged at a discharge rate of 15.0 g / min and a discharge temperature of 200 ° C. and was wound at a winding speed of 200 m / min to obtain a polyethylene-only tubular body having an outer diameter of 460 μm and a wall thickness of 75 μm. . Polycarbonate pipes were filled with 200 tubular bodies so that the packing density was 40%, and both ends of these hollow fibers were kept open at 15 mm.
A module adhered with the polyurethane resin used in Example 1 at a thickness of 1 was manufactured. Using this module, the adhesion durability test was conducted at 50 ° C × 3.5 kg / cm ² × 10 seconds (ON
When it was conducted in a cycle of (→ OFF), leakage occurred from the potting interface of the tubular body after 5000 times.

Example 2 Density 0.921 g / cm ³ , MI value 1.5, melting point 134
Low-density polyethylene (Showa Denko KK-made, Shorex M113) at ℃, density 1.19 g / cm ³ , MI value 3.2, melting point 183 ° C., ethylene / vinyl alcohol copolymer (ethylene content 32 mol%) ( 15. Using a hollow fiber manufacturing nozzle having two circular tubular discharge ports in which Soarnol DC3203 of Nippon Synthetic Chemical Industry Co., Ltd. is concentrically arranged, the low-density polyethylene is discharged from the inner discharge port. 0 g / min, discharge amount of the ethylene / vinyl alcohol copolymer from the outer discharge port is 1.0 g /
Each was discharged at a discharge temperature of 220 ° C. and a winding speed of 200 m / min to obtain a tubular body having an outer diameter of 470 μm, a wall thickness of 73 μm, and a thin film layer thickness of 5 μm. An adhesion durability test was conducted using 200 tubular bodies in the same manner as in Example 1, and a durability performance of 20,000 times or more was obtained.

In addition, 1500 of the tubular bodies have a diameter of 36 m.
m into a cylindrical container with a length of 130 mm, and both ends of the tubular body were adhered to each other with a thickness of 15 mm so as to be liquid-tight with a polyurethane adhesive while maintaining the open state, and a cylindrical heat exchange was performed. I made a container. With respect to this heat exchanger, a heat exchange test was carried out by flowing blood outside the tubular body and flowing warm water inside. Blood flow rate 6.0 l / min, warm water flow rate 10.0 l
The heat exchange efficiency E defined by the following formula when the blood inlet side temperature was 15 ° C. and the hot water inlet side temperature was 40 ° C. under the condition of / min was 0.80.

The pressure loss on the blood side is 15 mmHg,
The pressure loss on the hot water side was 0.22 kg / cm ² . Here, a similar heat exchanger was produced using the polyethylene-only tubular body described in Comparative Example 1, and a heat exchange test was carried out. The heat exchange efficiency E was 0.81. No decrease in heat exchange efficiency was observed.

E = (T _BO −T _BI ) / (T _WI −T _BI ) E: Heat exchange efficiency T _BI : Blood inlet temperature T _BO : Blood outlet temperature T _WI : Hot water inlet temperature

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[Procedure amendment]

[Submission date] February 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

That is, when this heat exchanger is used for blood treatment or the like, its functionality and reliability are dramatically improved. In addition, since the thickness of the thin film layer is extremely smaller than the wall thickness of the tubular body, a decrease in heat exchange efficiency due to compositing cannot substantially occur. The heat exchange tubular body of the present invention,
The cross-sectional shape does not necessarily have to be circular. For example, by providing fins on the outer side of the tubular body, it is possible to improve the uniform dispersibility of the tubular body bundle or increase the surface area in the cross-sectional direction to further improve the heat exchange efficiency.
In addition, the tubular body of the present invention is used as a weft thread and woven in a warp-like manner in a blind shape.
If the knitted tubular body sheet is used in the heat exchanger, the required amount of
Compared with the conventional type heat exchanger that only bundles tubular bodies,
It can be expected to improve the heat exchange efficiency.

Claims (3)

[Claims] 1. A tubular body for heat exchange of polyolefin, comprising a composite thin film layer comprising a hydrophilic organic polymer having a polar group on its outer surface. 2. The outer diameter is 150 to 1000 μm, the wall thickness / outer diameter ratio is 0.05 to 0.2, and the thickness of the thin film layer made of the hydrophilic organic polymer having a polar group is 0.01 to 20 μm. The tubular body according to claim 1. 3. The tubular body according to claim 1, wherein the hydrophilic organic polymer having a polar group is an ethylene / vinyl alcohol copolymer having an ethylene content of 20 mol% or more.