JPH0921024A - Crimping machine, crimping method and hollow fiber membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear-type crimper so designed that the shape of gears and the intergear minimum distance are specified respectively, and thereby a hollow fiber membrane can be stably imparted with wavy crimps without damaging the outer surface of the membrane. SOLUTION: A pair of gears each having tip-curved projections are rotated without mutual contact, and the intergear minimum distance D is set so as to be 1.1-15 times the outer diameter (d) of a hollow fiber membrane to be processed. The minimum radius of curvature R of each curved surface at the tip of each projection of the gear satisfies the relationship: 0.01<=d/R<=1. Thus, maladhesion in manufacturing hollow fiber membrane modules is reduced and crimped hollow fiber membranes improved in membrane performance and washing effect are obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a crimping machine used for industrially stably producing a crimped hollow fiber membrane, a crimping method therefor, and a hollow fiber membrane produced by the method. Is.

[0002]

2. Description of the Related Art Membrane modules using hollow fiber membranes are used for dialysis applications such as artificial dialysis, and filtration applications such as ultrafiltration and microfiltration. The hollow fiber membrane is usually a linear membrane, and is used as a module by bundling a large number of fibers, fixing one end or both ends with an adhesive, and opening them. Since the hollow fiber membranes are linear, they can be easily aligned, and a small space can be filled with a large amount of membrane area, which has the advantage of exhibiting high performance.

However, since the hollow fiber membranes are easily filled compactly, the gaps between the hollow fiber membranes are narrow, and it is difficult for the adhesive to enter between the hollow fiber membranes during bonding. Therefore, a hollow fiber membrane module having a poor seal is likely to be formed, which causes an increase in production cost. In addition, during use, in the case of artificial dialysis, the dialysate tends to flow to the outer peripheral portion rather than the central portion of the hollow fiber membrane bundle, and there is a drawback that waste products cannot be sufficiently exchanged at the central portion of the hollow fiber membrane bundle. doing. On the other hand, in the case of ultrafiltration or microfiltration in which the internal pressure is circulated and filtered, especially in the central part of the hollow fiber membrane bundle, the flow path resistance on the filtrate side (outside of the hollow fiber membrane) becomes high, so that the membrane performance cannot be sufficiently exhibited. Shortcomings and effects of backwashing during washing of hollow fiber membranes (meaning that fine particles adhering to the surface of the hollow fiber membranes are washed away by reversing the flow of liquid to the hollow fiber membranes) are difficult to appear However, there is a drawback that the filtration rate is lowered. Furthermore, in the case of ultrafiltration or microfiltration in which external pressure filtration is performed, the flow of the liquid to be filtered at the central portion of the hollow fiber membrane bundle is poor and only the outer peripheral portion functions, resulting in insufficient performance of the membrane. Since the effect of backwashing at the time of washing is difficult to appear, it has a drawback that the hollow fiber membrane is clogged in a relatively short period of time.

In order to solve these drawbacks, another fiber is spirally wound around the outer circumference of the hollow fiber membrane, or a hollow fiber membrane with fins in which protrusions are provided on a part of the hollow fiber membrane is used. It is known that the above-mentioned drawbacks can be ameliorated by applying a spiral or corrugated crimp to the yarn film (Japanese Patent Laid-Open Publication No. 6-58242).
No. 2-155858, JP-A No. 62-266106, etc.).

Here, for ordinary fibers which are not hollow fiber membranes, various crimping methods, for example, a method of pushing a fiber bundle into a narrow space and bending the fiber to give a permanent plastic deformation, or giving a twist to the fiber Moreover, there is a method of applying crimps by heating and cooling.

On the other hand, in the hollow fiber membrane, a liquid flows through the inside of the hollow fiber membrane. However, when the ordinary method of crimping fibers is used, the hollow portion is crushed or the outer surface of the hollow fiber membrane is damaged. Therefore, it cannot be used because of changes in membrane performance and problems with durability. As a method of crimping the hollow fiber membrane, a technique for heat-fixing the hollow fiber membrane by heat-treating the hollow fiber membrane wound across the bobbin etc. It is known that this is a technique of giving unevenness to the hollow fiber membrane by pressing and cooling.

[0007]

However, in the method of heat-treating a hollow fiber membrane wound around a bobbin so as to provide crimps, there is a defect that the membrane performance is changed, and the membrane performance inside and outside the bobbin is reduced. However, there is a drawback that it is difficult to obtain a product having different uniform properties. In the method of pressing the hollow fiber membrane against the heated wire mesh, the crimped yarn is deficient in that the location in contact with the wire mesh reduces the performance and durability of the hollow fiber membrane, and it is difficult to give large irregularities to the hollow fiber membrane. However, there is a drawback in that the above effect cannot be fully exerted.

The present invention has been made in view of the above problems, and it is possible to stably apply a wavy crimp to the hollow fiber membrane without damaging the outer surface of the hollow fiber membrane. The purpose is to provide a compactor.

[0009]

The crimping machine of the present invention for solving the above-mentioned problems is a crimping machine which gives a corrugated crimp to a hollow fiber membrane by passing a hollow fiber membrane between gears. In addition, the gears do not come into contact with each other, the tips of the gears are curved, and the shortest distance between the gears when the gears are closest to each other is 1.1 times or more of the outer diameter of the hollow fiber membrane to which the crimp is applied. It is characterized by being 15 times or less.

A gear-type crimping machine is one in which a thread is passed between a pair of gears to form a waveform, and a crimping gear, a driving gear, a driving motor for them and a crimping gear It consists of a belt conveyor attached to.
The crimping gear and the driving gear are mounted coaxially, and the shortest distance of the crimping gear is controlled by the engagement of the driving gear. Here, the shape of the crimping gear 1 generally used in the crimping machine has a U-shaped sharp corner as shown in FIG. If a crimp is applied to the hollow fiber membrane using such a gear, crushing will occur. The gear 2 used in the present invention has a shape having a curved projection at its tip as shown in FIG. FIG. 3 shows a gear with sharp corners (a) and a gear with curved protrusions (b).
FIG. Here, in the present invention, a gear having a curved tip has a minimum radius of curvature R (see FIG. 3) and an outer diameter of the hollow fiber membrane of 0.01 ≦ d / R ≦ 1, preferably A gear that satisfies the condition of 0.05 ≦ d / R ≦ 0.5. When d / R <0.01, it is not preferable that the crimp of the film is difficult to remain, or even if it remains, the crimp is less applied. If 1 <d / R, the film is likely to be crushed, which is not preferable. The shortest distance between the gears is represented by D in FIG.

The hollow fiber membrane passing between the gears may be wet or dry with a liquid such as water. Generally, it is preferable to pass the film in a wet state between the gears because crimping is more likely to occur. The temperature during crimping is not particularly limited, but is preferably 5 to 200 ° C, and preferably room temperature to 100 ° C.

The materials for the hollow fiber membrane used in the present invention include sulfone polymers such as polysulfone, polyether sulfone and polyallyl sulfone; cellulosic polymers such as ethyl cellulose, cellulose acetate and cellulose triacetate; polyamide; polyimide; Polyetherimide; Polyamideimide; Polyacrylonitrile; Polyphenylene oxide; Polyolefin polymers such as polyethylene, polypropylene, poly-4-methylpentene-1; Polyvinyl alcohol,
Examples thereof include polyvinyl alcohols such as ethylene vinyl acetate.

[0013]

The normal gear type crimping machine has a structure in which square gears mesh with each other, and ordinary fibers are bent at the corners of the square gear, and are stretched and plastically deformed to form crimps. Granted. The drive of the gear is also one side drive, and the other gear has a structure in which one gear rotates by touching one gear. On the other hand, in the present invention, the tip of the gear is curved and both gears are driven together so that the gears do not contact each other, so that good crimping can be achieved without crushing the hollow portion of the hollow fiber membrane. give. At this time, the shortest distance between the gears at the time of closest approach is set to 1.1 times or more and 15 times or less of the outer diameter of the hollow fiber membrane to which the crimping is applied. Since a large number of hollow fiber membranes to be crimped are supplied between the gears by aligning them, the minimum distance between both gears must be 1.1 times in order to prevent the hollow fiber membranes from collapsing. Further, even if the shortest distance between both gears exceeds 15 times, crimping can be applied by deepening the engagement of the gears, but the amplitude of the crimped hollow fiber membrane becomes large. , It becomes difficult to handle such as housing in a case.

[0014]

EXAMPLE A crimping machine in which gears having a minimum radius of curvature of 3 mm and a distance between the tips of 24 mm are meshed with each other and the biting height of both gears is adjusted to 8 mm and the minimum distance between both gears is adjusted to 2 mm. Between the gears, 100 polysulfone microfiltration hollow fiber membranes with an outer diameter of 500 μm were passed once to obtain crimped hollow fiber membranes. No scratches were observed on the outer surface of the obtained crimped hollow fiber membrane, and the hollow fiber membrane remained circular without being crushed. The crimp of the hollow fiber membrane is measured with it placed on a flat surface, and the cycle is 27 mm when it is regarded as a sine curve.
The amplitude was 1.3 mm.

Using 1800 crimped hollow fiber membranes, one end is fixed to the case with an adhesive in an open state, and the other end is sealed with an adhesive one by one to form a hollow fiber membrane module having an effective filtration length of 7 cm. It was made. Using this module, in accordance with the water purifier's clarification test method prescribed by the Japan Water Works Association,
When water having 10 ppm of kaolin dispersed therein was filtered under a constant pressure of 1 kg / cm ² , the filtration rate until the filtration rate decreased to 1 L / min was 2570 L.

For comparison, the outer diameter 500 used in the examples
A hollow fiber membrane module was prepared in the same manner as in the example without crimping a polysulfone microfiltration hollow fiber membrane, and the turbidity was measured. Filtration until the filtration rate dropped to 1 L / min. The volume was 1310L.

[0017]

By applying crimps to the hollow fiber membranes using the crimping machine of the present invention, the space of the hollow fiber membranes is increased and the adhesive is used when a large number of hollow fiber membranes are bonded together. It becomes easy to uniformly enter the space around the outer periphery of the hollow fiber membrane, and the production of hollow fiber membrane modules with poor adhesion in which the adhesive has not penetrated is reduced and the productivity is improved. Further, since the hollow fiber membrane is not crushed, when the hollow fiber membrane module is used, in the case of internal pressure filtration, the dialysis performance and the filtration performance are improved, and when backwashing, the hollow fiber membrane bundle has a sufficient central area. Can be cleaned and the cleaning effect is improved. In the case of external pressure filtration, since the membrane area effective for filtration is increased, more fine particles can be captured, the membrane performance is improved, and the backwash effect at the time of washing is also improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional U-shaped gear having sharp corners.

FIG. 2 is a diagram showing a gear showing an example of an embodiment of the present invention.

FIG. 3 is a partially enlarged view of a gear.

[Explanation of symbols]

 1 and 2 gears

Claims (3)

[Claims] 1. A crimping machine for crimping a hollow fiber membrane by passing a hollow fiber membrane between the gears, wherein the gears do not come into contact with each other, and the tips of the gears are curved surfaces. Moreover, the crimping machine is characterized in that the shortest distance between the gears when the gears are closest to each other is 1.1 times or more and 15 times or less of the outer diameter of the hollow fiber membrane to which the crimp is applied. 2. A method of crimping a hollow fiber membrane by passing a hollow fiber membrane between gears of a crimping machine, wherein gears having curved front ends do not come into contact with each other and The crimping method is characterized in that the shortest distance between the gears at the time of the closest approach is 1.1 times or more and 15 times or less the outer diameter of the hollow fiber membrane to which the crimp is applied. 3. A hollow fiber membrane provided with crimps by the crimping method according to claim 2.