JPS61215709A - Hollow fiber and production thereof - Google Patents

Abstract

PURPOSE:To obtain a hollow fiber consisting of two layers and having remarkably improved bonding strength between the layers, by using a spinning nozzle having two ring-shaped concentrically arranged dies, supplying a specific organic polymer separately to the above dies and carrying out the spinning, drawing and heat-setting of the polymer. CONSTITUTION:Organic polymers of different kinds (e.g. polyethylene, poly propylene, etc.) or of the same kind and having different melt viscosity index values (MI values) are supplied separately to the dies of a hollow-fiber spinning nozzle furnished with two ring-shaped concentrically arranged dies and a hollow fiber composed of the outer and the inner layers is produced by the composite melt-spinning of the polymers. The hollow fiber is optionally annealed and is drawn to form a number of minute voids exclusively in the outer layer. The objective hollow fiber composed of an outer layer having minute voids and a continuous inner layer free from through-holes and bonded to the outer layer can be produced by the heat-setting of the above drawn fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a hollow fiber made of an organic polymer, and particularly to a hollow fiber useful for use as a heat exchanger for artificial lungs and the like.

Conventional technology> Artificial lungs are used as heart-lung auxiliary devices for surgical procedures and as replacement devices for lungs whose function has decreased. A heat exchanger is indispensable as the ninth means, and prior art examples include Japanese Patent Publication No. 55-2982 and Japanese Patent Application Laid-Open No. 57-398.
The details are described in Publication No. 54 and the like.

<Problems to be solved by the invention> Conventionally, the material for the pipes of the heat exchanger used as an accessory device for oxygenators is often made of stainless steel, which has good heat conductivity and good heat resistance. However, when assembling it into a heat exchanger, there are problems such as how to seal the end face, destruction of particles in the blood by the edge of the end face, and reactivity with blood components with a complex composition.

Hollow fibers made of organic polymers are sufficient to solve the problems of conventional materials such as those mentioned above, and are sufficient as pipes for heat exchangers. There are some problems. In other words, when these pipes are incorporated into a heat exchanger, it is generally necessary to arrange the pipes and partition them so that the materials on both the heat supply side and the heat absorption side do not mix.Botting technology using organic resin is used as a means for this purpose. Although this is often the case, it is not good for the adhesion of organic polymers to organic resins.

Means for Solving the Problems> Therefore, the present inventors conducted intensive studies to solve the above-mentioned problems of hollow fibers for heat exchangers made of organic polymers, and as a result, the surface layer portion of the hollow fibers was developed. He discovered that by providing micropores in the material, the adhesion to the organic resin used for botting could be dramatically improved, and completed the present invention.

That is, the gist of the present invention is that the outer layer and the inner layer are composed of different types of organic polymers or the same type of organic polymers having different melt viscosity indexes (MI values),
The outer layer having minute pores and the inner layer which is continuous and has no through holes are bonded to each other, and the sum of the thicknesses of both is 2 to 500μ, and the inner diameter is 50 to 2000μ. A hollow fiber obtained by composite melt spinning with a W characteristic is used, and a hollow fiber with two annular discharge ports arranged concentrically is used for manufacturing the hollow fiber. Organic polymers of the same kind with different viscosity indexes are separately supplied and melt composite spun to form a hollow fiber upper comb having two layers, and the hollow fibers are stretched as they are or after annealing treatment to form an outer layer. It is composed of different types of organic polymers or the same type of organic polymers with different melt viscosity indexes, which are characterized by producing a large number of micropores in the outer layer and then being heat-set. The present invention provides a method for manufacturing a hollow fiber in which a hollow fiber is bonded to an inner layer having no holes.

The organic polymers conveniently used in the present invention include polyethylene, polyglopylene, poly-3-methylbutene-1, poly-4-methylpentene-1, polyvinylidene fluoride, polyethylene terephthalate, lyoxymethylene, or these metal-based polymers. Crystalline polymers such as silicon, urethane, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer or ethylene vinyl chloride copolymer can be mentioned.

The hollow fibers of the present invention may have any shape, but considering that they are used for heat exchange purposes, it is preferable that they have sufficient mechanical strength.
Particularly preferred is μ and an inner diameter of about 50 to 2000P.

The hollow fiber of the present invention uses a hollow fiber manufacturing nozzle having two annular discharge ports arranged concentrically, and separates different kinds of organic polymers or the same kind of organic polymers with different iM values into each discharge port. feeding and melt spinning to obtain a hollow fiber with two layers,
The hollow fiber can be obtained either as it is or after annealing, stretching it to form a large number of nine minute holes only in the outer layer, and then heat-setting it.

The MI value of the organic polymer constituting the outer layer employed in the present invention is preferably in the range of [11 to 10]. M
The I value is measured by A8TM D-1238, and most preferably ranges from 1 to 6. This range is a desirable range for stably producing a medium-sized yarn with stable micropores tV in the outer layer. ,
Further, in the region of M'L value of 10 or more, the development of micropores becomes insufficient in making the film porous by stretching.

In addition, the MI value of the organic polymer that makes up the entire inner layer is 15 to 5.
It is preferably in the range of 0. If M is less than 15, through holes are likely to be formed in the inner layer, and if it exceeds 50 t, the melt viscosity becomes too low, making it difficult to perform stable spinning. When using different types of polymers, it is sufficient to use polymers that tend to form micropores under the same stretching conditions in all outer layers.

Any temperature may be used as long as the spinning temperature of the organic polymer is such that 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 and stable spinning will be difficult. Therefore, it is preferable that the range is from the melting point to (melting point +80°C).

When the spinning draft is less than 30, the orientation of the hollow fiber becomes low, and sufficient elongation cannot be obtained during subsequent drawing, and the amount of drawing required to open micropores is 1i [inability to maintain]. It is desirable that the Lv is 30 or higher.

Does the annealing temperature affect the internal crystal structure? Any temperature may be used as long as it stabilizes the temperature, but the melting point ~ (
The melting point is preferably in the range of −100° C.).

This is a process in which micropores are developed in the outer layer of the hollow fiber after heat treatment during stretching, and in order to develop micropores, the crystal itself is not deformed and the crystal interfaces are stretched at a temperature that causes them to separate. There is a need to.

For this purpose, it is preferable to stretch at a relatively low temperature below (melting point -100°C).

Heat setting is a step in which the micropores developed by cold stretching are made thicker and stabilized as the case may be, and it is necessary to draw at a temperature at which the structure itself is less deformed and the micropore structure is stabilized. For this purpose, a range of melting point to (melting point -60°C) is preferable. Since the hollow fiber obtained by the present invention has micropores in the tube wall portion, the organic resin used in the botting process when assembled into a heat exchanger It is possible to dramatically improve the adhesion with the heat exchanger not only by the adhesive force at the interface but also by the mechanical bonding force caused by the structure and solidification of the organic resin inside the microscopic holes. If its reliability can be increased at all.

Furthermore, since the medium yarn obtained by the present invention is shaped by the drawing method as described above, it has good orientation and excellent mechanical strength.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Polyethylene with density (L968 melt index 5.5) (Mitsui Petrochemical Co., Ltd. Exhibition Hi-Zex 2200J
) and polyethylene with a density α92 melt index of 2 (Mitsui Petrochemical Co., Ltd. Ultxex 5021F)
') Q A hollow fiber manufacturing nozzle rotating two annular discharge ports arranged concentrically, the high density polyethylene is discharged from the outer discharge port at a total discharge temperature of 170°C and a discharge linear velocity of 8 cm/min. , the low-density polyethylene was discharged from the inner discharge port at a temperature of 170°C and a linear discharge velocity of 2α/min.
Extrusion and winding at a winding speed of 400 m/min under these conditions. At this time, spinning draft 5 of high density polyethylene
000, low density polyethylene spinning trough) 2[], 0
00 / Obtained A9 undrawn 9 yarn dimensions are inner diameter 30
The thickness of the high-density polyethylene layer was 60 μm, and the thickness of the low-density polyethylene layer was 6 μm. This unstretched hollow fiber gold 1
The film was annealed by passing it along a roller heated to 15° C. for 140 seconds. Subsequently, it was stretched for 40 ts between rollers kept at 20°C, further stretched by 160% at 105°C, and further heated under heat cera in a box heated to 115°C under foot length to obtain a hollow fiber. .

The tube wall thickness of the obtained hollow fiber was 50μ, and the inner diameter was 240μ.
A friend of mine. The hollow fibers were subjected to a botting process using a urethane adhesive (a-aaos/N-4221, manufactured by Nippon Polyurethane Co., Ltd.), and after curing at room temperature for one week, the bottling portion was cut. The cut surface was visually observed using an optical microscope, and the results showed that there were no hollow fibers that had peeled off from the urethane resin.

Comparative Example 1 The hollow fibers of Example 1 after the annealing treatment were subjected to botting with urethane adhesive in the same manner as in Example 1, and after curing for one week, the botting portion was cut and the t0 cut surface t was examined with the naked eye using an optical microscope. As a result of observation, most of the hollow fibers were peeled off from the urethane resin. Example 2 Polyethylene with density α968 and melt index S5 (Hyzex 2200J manufactured by Mitsui Petrochemical Co., Ltd.)
Polypropylene with density α910 and melt index 15 (Ube Industries, Ltd. UBFi Polypro J-115G)
) were arranged concentrically and had two annular discharge ports, and the high-density polyethylene was discharged from the outer discharge port at a temperature of 190°C and a linear discharge velocity of 8 cm/m1ns inside. The total discharge temperature of the polypropylene from the discharge port was 190°C, and the discharge linear velocity was CL 7 cm7.
Extrusion winding speed 200rn/m under conditions of min.
It was wound up in. At this time, the spinning draft of high density polyethylene was 2500, the spinning draft of polypropylene was 30,
It was 000.

The dimensions of the obtained unstretched hollow fibers were as follows: inner diameter 350μ, high density polyethylene layer thickness 35μ, polypropylene layer thickness 5μ.
It was μ. This undrawn medium receiving yarn was heated to 115°C f'
It was annealed for 140 seconds by passing over an L-shaped roller at a fixed length.

Subsequently, it was stretched by 4 degrees between rollers kept at 20°C, further stretched by 160% at 105°C, and further heat-set at a foot length in a box heated to 115°C to obtain hollow fibers. .

The tube wall thickness of the obtained hollow fiber was 33μ, and the inner diameter was 340μ.
A friend of mine. The hollow fibers were subjected to a botting process using a urethane adhesive (0-4405/N-4221 manufactured by Nippon Polyurethane Co., Ltd.), and after curing for one week at room temperature, the bottling portion was completely cut off.

Visual observation of the cut surface using an optical microscope revealed that there were no hollow fibers that had separated from the urethane resin.

Comparative Example 2 The hollow fibers of Example 2 after the annealing treatment were subjected to botting processing with urethane adhesive in the same manner as in Example 2, and cured for one week.
After that, I cut the potting part. As a result of visual observation using a cut surface tl-Gengaku microscope, it was found that most of the hollow fibers had peeled off from the urethane resin.

Example 3 Polyoxymethylene (Tenac 3010 manufactured by Asahi Kasei Corporation) with a melt index of 56 and ethylene vinyl acetate copolymer (L925 with a melt index of 30)
Nippon Unicar Co., Ltd. fiNUC ethylene copolymer DQD, T-3868)? Using a hollow fiber membrane forming nozzle with two annular discharge ports arranged concentrically,
The polyoxymethylene is discharged from the outer discharge port at a temperature of 1.
80°C, discharge linear velocity 6 cm/min, and the ethylene vinyl acetate copolymer gold discharge temperature 18 from the inner discharge port.
It was extruded at 0° C. and a discharge linear velocity of 115 cm/min, and wound up at a winding speed of 200 m/min. At this time, the spinning draft of polyoxymethylene was 5333, and the spinning trough of ethylene vinyl acetate copolymer was 40,000.

The dimensions of the obtained undrawn hollow fibers were as follows: inner diameter 300μ, polyoxymethylene layer thickness 30μ, and ethylene vinyl acetate copolymer layer thickness 4μ. This unstretched hollow fiber'! ! l-
The sample was annealed for 140 seconds by passing over a roller heated to 115° C. over a constant length. Subsequently, it was stretched by 40% between tL specific rollers kept at 30°C, and further stretched at 110°C.
Then, the fibers were stretched by 160%, and then heat-set in a box heated to 120°C under foot length to obtain hollow fibers.

The tube wall thickness of the obtained hollow fiber was 30μ, and the inner diameter was 292μ.
Met. The hollow fibers were bonded with a urethane adhesive (C-44037N-4221, manufactured by Nippon Polyurethane Co., Ltd.), cured for one week at room temperature, and then completely cut off at the bottom. As a result of visually observing the cut surface using an optical microscope, no hollow fibers were found to have peeled off from the urethane resin.

Comparative Example 3 The annealed hollow fiber of Example 5 was subjected to botting using a urethane adhesive in the same manner as in Example 3, and after curing for one week, the botting portion was cut. Cutting surface T - Visual observation using a biological microscope revealed that some hollow fibers had peeled off from the urethane resin.

Claims (1)

[Claims] 1. The outer layer and the inner layer are composed of different types of organic polymers or the same type of organic polymers with different melt viscosity indexes (MI values), and the outer layer has micropores and the inner layer does not have continuous through holes. A joined hollow fiber obtained by composite melt spinning, characterized in that the sum of both thicknesses is 2 to 500μ and the inner diameter is 50 to 2000μ. 2. Using a hollow fiber production nozzle having two annular discharge ports arranged concentrically, different or similar organic polymers (with different MI values) are separately supplied to each discharge port. Melt composite spinning is performed to obtain a hollow fiber having two layers, and the hollow fiber is stretched as it is or after annealing to create a large number of micropores only in the outer layer, and then heat set. A method for producing a hollow fiber comprising organic polymers of different types or of the same type having different melt viscosity indexes, in which an outer layer having micropores and an inner layer having no continuous through holes are joined. 3. The melt viscosity index (MI value) of the organic polymer forming the outer layer of the hollow fiber during spinning is set to 0.1 to 10, and that of the organic polymer forming the inner layer is set to 15 to 50. A method for manufacturing a hollow fiber according to claim 2, characterized in that: 4. The method for producing hollow fibers according to claim 2 or 3, wherein the spinning temperature is from the melting point of the organic polymer to (melting point +80°C). 5. The method for producing a hollow fiber according to claim 2, 3, or 4, characterized in that the spinning draft is 30 or more. 6. The method for producing a hollow fiber according to any one of claims 2 to 5, wherein the heat setting temperature is from the melting point to (melting point -60°C).