JPH0733602B2 - Multi-tube hollow fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hollow fiber as a separation membrane, and more particularly to a multiple hollow fiber as a novel separation membrane.

Examples of solution-based membrane treatment methods include reverse osmosis and ultrafiltration, electrodialysis, electrophoresis, and dialysis.
Separation is performed by using the pressure difference as the driving force in the reverse osmosis and ultrafiltration methods, the potential difference in the electrodialysis method and the electrophoresis method, and the concentration difference in the dialysis method. Further, a membrane separation method utilizing a temperature difference has also been proposed. In addition, substances with extremely high molecular weight or substances called dispersed particles rather than solutes are separated by filtration with a precision membrane.

When the separation membrane having such a selective permeability is put to practical use, it is used as a flat membrane-shaped module and a secondary-processed module of a rolled shape, a pleated shape, a tubular shape, and a hollow fiber shape. The module can have a large membrane area per volume. In addition, because of the small amount of fine particles in the liquid, it is widely used in various fields such as electronics industry and other ultrapure water, artificial dialysis water production, chemical liquid, and infusion purification.

(Prior Art) However, in a conventional hollow fiber module, a large number of single-type hollow fibers are bundled, and a specific component according to the properties of the membrane is separated by an internal pressure method or an external pressure method. The target degree of separation is increased by performing three-step treatment. Therefore, in order to separate many kinds of components, it is necessary to connect many kinds of devices and perform separation operation.

Examples of hollow fibers that have improved such drawbacks include double-layered or three-layered hollow fibers.
There is 2-124929. However, in the membrane, two or more layers are strongly adhered to each other, and when the separation operation is performed using such a hollow fiber membrane, the degree of separation of a certain specific component can be increased, but a plurality of layers are simultaneously formed. It is not possible to efficiently separate the components. A multiple hollow fiber in which two or more layers are not attached to each other is disclosed in JP-A-53-100977.

(Problems to be solved by the invention) However, in the multiple hollow fibers which are not adhered to each other, the internal hollow fibers cause a waving phenomenon due to the flow of the liquid, resulting in an unbalanced flow or yarn breakage. It may happen.

In addition, it is possible to form a multi-type hollow fiber by combining hollow fibers having different diameters obtained by a usual method and inserting a hollow fiber having a small diameter into the hollow portion of a hollow fiber having a large diameter. It has the drawbacks that the membrane surface of the yarn is damaged, the flow path between the hollow fibers is not constant, and the productivity is extremely low.

The present invention has been achieved as a result of intensive studies aimed at eliminating such drawbacks and increasing productivity.

The present invention provides a novel multiple hollow fiber different from the conventional one.

(Structure of the Invention) That is, the present invention provides a multi-concentric hollow fiber arranged in multiple concentric circles on the outside or inside of a hollow fiber and used for a separation membrane, wherein at least one of an outer wall and an inner wall of adjacent hollow fibers is used. The multi-tube hollow fiber is characterized in that a portion thereof is continuous or intermittent in the spinning direction to form a bridge.

The structure of the multi-tube hollow fiber according to the present invention will be described with reference to the drawings, taking a double-tube hollow fiber as an example.

FIGS. 1 (a) to (d) show schematic views of the cross section of a double-tube hollow fiber composed of hollow fibers having protrusions on the inner wall or outer wall of double adjacent hollow fibers. FIG. 1 (a) is an example having protrusions from the outer surface of the inner tube to the outside, and FIG. 1 (b) is an example having protrusions from the outer tube to the inner surface, FIG. 1 (c). ) Is an example of these mixed types, and (d) is an example in which the positions of the inner tube projection and the outer tube projection match.

The shape and number of these protrusions are not particularly limited, and may be selected according to the purpose so that the fluid uniformly flows in the flow path.
Further, these protrusions may be provided so as to be parallel to the length direction of the hollow fiber, or may be provided in a spiral shape. As a method of providing the protrusion, the method of using a spinneret which allows the protrusion to be formed during the spinning of the hollow fiber is most productive.

Figures 2 and 3 show the structure of such a base.
It is a figure.

Usually, a spinneret used for spinning a hollow fiber has a double annular structure called a tube-in-orifice type, in which a liquid (core liquid) or gas is supplied from an inner tubular channel and an outer annular channel is supplied. The spinning solution is extruded to produce hollow fibers by a wet or dry-wet method.

The structure of the spinneret and the structure of the multiple hollow fibers for producing the multiple hollow fibers according to the present invention will be described below.

FIG. 2 is an enlarged view of a longitudinal section of one multiple hole of a spinneret for spinning a double hollow fiber, which is an example of a spinneret for spinning multiple hollow fibers according to the present invention, and FIG. 3 is shown in FIG. It is an enlarged view of one multiple hole seen from the discharge port side of the spinneret. FIG. 1 (d) is an enlarged cross-sectional view of the double hollow fiber according to the present invention spun using this spinneret.

In FIGS. 2 and 3, 1-1 is a portion around the multiple holes of the spinneret, 2-2 is an outermost annular flow path of the multiple holes, and a film forming the outer hollow fiber is formed here. A liquid (hereinafter referred to as a dope) flows. Reference numeral 3-3 is an annular flow path for flowing a liquid or gas as a core agent to form a space between the multiple hollow fibers. Reference numeral 4-4 is an annular flow path through which the dope that forms the hollow fiber inside the double hollow fiber flows.
Reference numeral 5-5 is a tubular flow path for flowing a liquid or gas as a core agent for forming the hollow portion of the inner hollow fiber.

6-6 'and 7-7' are concave cut portions provided in the annular flow path wall.

Also, in FIG. 1 (d), 8-8 is the outside of the double hollow fiber, and 9-8.
-9 is the inner hollow fiber, 10-10 is a protrusion formed by 6-6 'in FIGS. 2 and 3 in the inner circumferential spinning direction of the outer hollow fiber 8-8, and 11-11 is Similarly FIGS. 2 and 3
7-7 'in the figure is a protruding portion formed in the outer peripheral spinning direction of the inner hollow fiber 9-9.

Here, 10-10 and 11-11 in FIG. 1 (d) are not in contact with each other because they are separated by the liquid or gas serving as the core agent immediately after the dope is discharged from the die. The viscoelasticity of a fairly viscous dope prepared by dissolving a substance in a solvent causes a ballast effect, and in part forms a bridge which is the point of the present invention.

Due to the bridge formation of the protrusions 10-10 and 11-11, the arrangement of the outer hollow fibers and the inner hollow fibers is kept substantially concentric, and it is possible to prevent the corrugation phenomenon of the inner hollow fibers which occurs when the liquid is poured inside. it can.

In Fig. 1 (d), 10-10 and 11-11 show a state in which both the left and right are not bridged, but the cross-sections at various points in the lengthwise direction indicate that there are intermittent bridges. Is formed.

The concave cut portion of the annular flow path wall may be provided at two places like 6-6 'and 7-7' in FIGS. 2 and 3, or 6-
It is possible to have neither 6'or 7-7 '.

Further, in FIGS. 2 and 3, concave cut portions are provided on the left and right with the central portion being symmetrical, but this may also be the state in which either one is not provided. On the contrary, the center part should be symmetrically shaped like a cross 4
It may be provided in one place or more. A hollow fiber spun using such a spinneret has a shape as shown in FIGS. 1 (a) and 1 (b).

The cross section of the concave cut portion of the annular flow passage wall may be U-shaped or V-shaped, and the depth is the full thickness of the partition wall of the annular flow passage. It goes without saying that they are easy to bridge.

The depth of the cut is at most 1 mm from the discharge side.

Further, the outer hollow fiber 8-8 and the inner hollow fiber 9-9 may be formed into the same film by using a dope composed of the same film material and composition,
The composite hollow fiber may be formed by using a dope having a different membrane material and composition depending on the purpose of use.

As a matter of course, a plurality of core agents used may be the same liquid, may be a combination of different liquids, or may be an arbitrary combination such as a combination of gas and liquid depending on the purpose and the membrane material.

In addition, all of FIGS. 1 to 3 show a spinneret for spinning a double hollow fiber and a double hollow fiber spun using the spinneret, but the same principle is applied to a hollow fiber having three or more layers. Needless to say, it is possible to use a spinneret having three or more layers, and the spinning method can be applied to either a wet method or a dry-wet method.

[Brief description of drawings]

1 (a), (b), (c), and (d) are enlarged cross-sectional views showing an embodiment of the double hollow fiber according to the present invention. FIG. 2 is an enlarged cross-sectional view of one multi-hole portion of a spinneret for spinning a double hollow fiber according to the present invention. FIG. 3 is an enlarged view of one multi-hole portion of the base viewed from the discharge direction.

Claims (1)

[Claims] 1. A multi-tubular hollow fiber arranged in a multi-concentric shape on the outside or inside of the hollow fiber, which is used for a separation membrane,
A multi-tubular hollow fiber, wherein at least one portion of an outer wall and an inner wall of adjacent hollow fibers is continuous or interrupted in the spinning direction to form a bridge.