JP2736687B2 - How to align hollow fiber bundles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to the production of hollow fiber membranes using various polymers as raw materials, and relates to a method for arranging the hollow fiber membrane bundles.

(Problems to be Solved by the Prior Art and the Invention) Hollow fiber membranes having a selective permeation function are used for solution separation and gas separation by ultrafiltration, reverse osmosis, etc., and are used in medical, electronic, food, and other industries. Used in various industries.

In the production of such a hollow fiber membrane, melt spinning or dry-wet or wet-spinning is generally performed. In the latter dry-wet or wet-spinning, starting from the discharge of the raw material dope from a nozzle, coagulation and residual solvent forming the film are formed. Manufacturing through a series of processes such as washing with water, drying with a wet membrane as a dry membrane, and immersion in a humectant solution to maintain the performance as a selectively permeable hollow fiber membrane after drying. Methods are known. At this time, a case where one hollow fiber membrane is spun in one independent line and a case where many hollow fiber membranes are spun simultaneously in the same line are considered. Obviously, in order to obtain a large amount of hollow fiber membranes by the former production method, a multi-line is necessary. Considering the cost in terms of equipment, the latter method of spinning a large number of fibers simultaneously is advantageous. However, conversely, when a large number of hollow fiber membranes are simultaneously fed to the same line, there arises a problem that cannot occur when spinning one by one. One of the problems is a disorder of the yarn bundle caused by twisting, sagging, entanglement or the like of the manufactured hollow fiber bundle.

That is, when simultaneously spinning a plurality of hollow fiber membranes, equipment such as a roll is naturally required between these steps to flow a large number of hollow fiber membranes from one step to the next step. Except in a special case where the axes of all the rolls are horizontal and perpendicular to the direction of travel of the hollow fiber membrane, each of the multiple hollow fiber membranes flowing through the line passes through the rolls, except in the special case where the axes of all the rolls are horizontal. Lateral forces will be applied. Due to this lateral force, it is extremely difficult for a large number of hollow fiber membranes to move on the same plane, and each of the hollow fiber membranes flows in a twisted state or extremely slack with respect to other yarns. Appears as a result.

Yarn twisting is a phenomenon that occurs when one or more yarns ride on another yarn as a result of a lateral force being applied to a hollow fiber membrane on a roll. The running distance of each thread changes subtly by
It is considered that the slack and twist twisted and dispersed in the length direction of the hollow fiber that was forcibly pulled are concentrated in one place, and the slack is greatly slackened during running in the hollow or liquid. As described above, there is an extremely large problem that a large number of hollow fiber membranes do not flow in an orderly arrangement, are spun in a disordered state, and remain after a series of steps.

Further, when the hollow fiber is wound by a circular bobbin, the circumference of the hollow fiber changes as the yarn is wound on the bobbin, and the hollow fibers having essentially different lengths form a bundle, and are wound around the bobbin. Since the drawn yarn bundle naturally has a curvature of a precision after being cut into a predetermined length, or if it is forcibly stretched, the curvature appears as a disorder of the yarn. The disturbance of the yarn bundle causes a problem that the number of filled hollow fibers during assembly of the hollow fiber membrane module is reduced.

Conventionally, in order to eliminate the above-described disturbance of the yarn bundle, it is necessary to perform an operation of extracting a turbulent yarn existing inside or on the surface of the bundle after the bundle is taken. However, this operation is extremely complicated and requires There is a drawback in that, when extracting an existing turbulent yarn, other yarns are damaged or a large number of turbulent yarns are extracted, resulting in a decrease in the number of hollow fibers in the yarn bundle. Further, no substantial improvement can be expected with this method, and it is impossible in circumstances to completely eliminate the irregularity of the yarn bundle.

(Means for Solving the Problems) As a result of various studies to solve the above problems, the present inventors have found a tying method that does not involve the operation of extracting a turbulent yarn.

That is, the present invention relates to a method for arranging a hollow fiber bundle comprising a selectively permeable hollow fiber membrane, wherein the yarn bundle suspended and held at the upper end is immersed in a liquid other than water, and then the yarn bundle is pulled up. Another object of the present invention is to provide a method for aligning hollow fiber bundles, wherein the liquid is caused to flow in the axial direction of the yarn bundle by lowering the liquid.

The type of liquid other than water used in the present invention is not particularly limited as long as it does not damage the membrane itself such as dissolving the hollow fiber. It is necessary for the viscosity to be not more than 1000 cp at 20 °, and more desirably about 1 to 200 cp. If the viscosity of the liquid is too high, the speed of flowing through the hollow fiber decreases, and if the viscosity is lower than necessary, the force exerted by the liquid on each hollow system constituting the yarn bundle cannot be obtained sufficiently. This is not preferred because the sizing effect is reduced.

Examples of the liquid used include, for example, various alcohols, carboxylic acids, amines, ethers, esters, ketones, etc., alone or a mixture thereof, or a water-soluble alcohol, ether, carboxylic acid, amine, etc. , Aqueous solutions of various organic and inorganic salts, aqueous solutions of surfactants, and mixtures thereof. On the other hand, if water, methanol, or the like is used alone, the viscosity of itself is relatively low, so that the effect of sizing is difficult to obtain,
It should be noted that it is more effective to use a mixture with other components.

Here, when the present invention is illustrated with respect to a manufacturing method by dry-wet or wet-spinning, for example, using a water-based coagulation liquid, and then, in the case of a hollow fiber obtained by washing with water, when directly drying from a state wetted with water, It has the property of losing the original membrane performance, and in order to maintain the membrane performance, the membrane is generally dried through treatment with an aqueous humectant solution. Therefore, in this case, the bundling step should be performed after the bundling and before the drying step, and the liquid used is more preferably an aqueous solution containing a humectant. When water alone is used, the immersion step in the humectant aqueous solution may be required again before shifting to the drying step, and the entire step may be complicated.

The humectant aqueous solution used in the above case, for example, ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, aqueous solutions of water-soluble aliphatic polyhydric alcohols such as glycerin, surfactants represented by sodium dodecyl sulfate and the like Aqueous solution,
Further, a mixed solution thereof may be used.

Further, in the present invention, as a method of bringing the hollow fiber into contact with a liquid other than water and flowing the liquid, a vertically suspended yarn bundle is immersed in the liquid, and then the yarn bundle is pulled up from the liquid or immersed in the liquid. Can be used.

Although a certain degree of sizing effect can be expected when the liquid is supplied to the outer peripheral portion of the yarn bundle, the hollow fibers located at the outer peripheral portion are effectively tied, but the hollow fibers located at the central portion of the yarn bundle are effectively bundled. The sizing effect is not sufficient, and as a result, a defective yarn bundle is often formed inside the yarn bundle.

When the liquid is caused to flow by contacting the hollow fiber with the liquid, it is necessary to bind the hollow fibers to each other, such as a rubber band stopper, only at the upstream end of the liquid flow among the ends of the hollow fiber bundle. This is to prevent each hollow fiber constituting the yarn bundle from dropping off from the bundle due to the flow.

Due to the above-described process, a defect such as a bend of the yarn bundle before being bundled from the circular bobbin becomes an irregular length of the hollow fiber at the downstream end of the fluid flow after the completion of the bundle. However, by cutting the difference in the length of this portion, it is possible to obtain a good yarn bundle having a uniform length.

(Operation) The method according to the present invention significantly reduces the sliding frictional resistance acting between the hollow fibers by bringing the liquid into contact with the hollow fiber bundle having one end bound, and further allows the liquid to flow relative to the hollow fiber. Tension is generated in each hollow fiber by the flow resistance at the time of making the hollow fiber stretched linearly in the flow direction of the liquid as a result of the tension, so that the whole bundle is aligned. Things.

(Examples) Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In practicing the present invention, the following two types of yarn bundles, which were not bundled after being bundled, were used.

Bundle A: Selectively permeable hollow fiber membrane 40 having an inner diameter of 210 μm and an outer diameter of 340 μm
It is a bundle of about 45 cm long consisting of 00 pieces, but the whole bundle has a wavy curve.

Bundle B: Permselective hollow fiber membrane 72 with 400 μm inner diameter and 680 μm outer diameter
It is a bundle of about 45 cm in length, consisting of cracks near the center of the bundle, and the hollow fibers are divided into two groups. In addition, bent yarns are included in about 5% of the whole.

Example 1 One end of the bundle A was bound with a rubber band, and the whole was immersed in a 30% by weight aqueous glycerin solution (viscosity: about 2.5 cp, 20 ° C.), and then the yarn bundle was 12 m / min. When pulled up from the aqueous solution at the speed described above, a straight cylindrical thread bundle extending straight was obtained.

Example 2 The entire bundle B was immersed in a 0.1% by weight aqueous solution of sodium dodecyl sulfate (viscosity of about 1 cp, 20 ° C.) filled in a cylindrical container, and the upper end of the bundle was fixed with a clamp in the liquid. When the yarn bundle was rapidly lowered until it was below the lower end of the yarn bundle, the yarn bundle was extremely good without any cracks in the central portion and no bent yarn observed before the bundle was tied.

(Effect of the Invention) By the method of the present invention, problems such as damage of the hollow fiber or shortage of the number of the hollow fiber are solved, and a good hollow fiber in which the number of hollow fiber membrane modules to be filled can be increased as compared with the case of a turbulent yarn bundle. A bunch is obtained.

Also, if an aqueous humectant solution is used as the sizing solution, the step of immersing the hollow fiber membrane in the aqueous humectant solution can be omitted.
It has the effect of two birds per stone with bunching and moisturizer impregnation.

Therefore, the present invention greatly contributes to the development of the industry in the field of hollow fiber membranes.

Claims (2)

(57) [Claims] In a method for arranging a hollow fiber bundle comprising a selectively permeable hollow fiber membrane, the suspended fiber bundle held at the upper end is immersed in a liquid other than water, and then the yarn bundle is pulled up. Alternatively, the liquid is caused to flow in the axial direction of the yarn bundle by lowering the liquid, whereby the hollow fiber bundle is aligned. 2. The method according to claim 1, wherein the liquid other than water is an aqueous solution containing a humectant.