JPS6054402B2 - Manufacturing method of recycled cellulose hollow fiber - Google Patents

Description

Detailed Description of the Invention The present invention relates to a method for producing regenerated cellulose hollow fibers.More specifically, the present invention relates to a method for producing regenerated cellulose hollow fibers. The present invention relates to an industrially advantageous method for producing regenerated cellulose hollow fibers from cellulose ester hollow fibers.

BACKGROUND ART Methods using permeable membranes for substance separation are attracting attention in fields such as seawater desalination, wastewater treatment, artificial organs, gas separation, and the food industry, and related technological development is progressing rapidly.

One of the membrane materials is a hollow fibrous membrane, which has the advantage of increasing the membrane area per unit space and eliminating the need for a support as a reinforcing material compared to flat membranes. It is estimated that hollow fibers as separation membranes will be used in more and more fields in the future. The present invention uses cellulose ester and has excellent permselectivity for ultrafiltration and hemodialysis.In addition, it has excellent processability when assembled into modules, and the hollow fibers are re-wet after being washed and dried. The present invention relates to an industrially advantageous method for producing regenerated cellulose hollow fibers that have good dimensional stability and performance stability when smelled, have high roundness, have a uniform cross-sectional shape, and are free of pinholes.

Conventionally, regenerated cellulose hollow fibers have been produced by the ammonia method, but recently a method of producing hollow fibers using cellulose derivatives, particularly cellulose acetate, and deacylating them to produce regenerated cellulose hollow fibers has been attracting attention. .

However, since the cellulose acetate used in these methods has a very low molecular weight, the shape stability and strength of the regenerated cellulose hollow fibers obtained are insufficient. It was necessary to increase it. That is, a method has been adopted in which cellulose acetate hollow fibers are stretched and oriented. However, when such measures are taken, the permeation performance of the regenerated cellulose hollow fibers obtained decreases significantly, and once a practical level of strength and morphological stability is achieved, the permeation performance decreases to the point where it can no longer be used for practical use. That's what happens. Regenerated cellulose hollow fibers manufactured from cellulose acetate, which have such high strength, excellent shape stability, and excellent permeability, have not yet appeared, and their development is awaited. Therefore, the present inventors are currently considering using cellulose ester to obtain regenerated cellulose hollow fibers that do not have the above-mentioned disadvantages. Depending on the requirements, a plasticizer such as glycerin is applied and then stretched and dried. The present invention was completed based on the discovery that regenerated cellulose hollow fibers having good properties can be obtained by this method.

The gist of the present invention is to substantially deacylate cellulose ester hollow fibers, thoroughly wash them with water, and moisten them. The purpose of this method is to dry the stretched regenerated cellulose hollow fibers in air or inert gas at 50° C. or higher (hereinafter referred to as stretch drying).

The cellulose ester used in the present invention includes cellulose acetate, cellulose propionate, cellulose butyrate, etc., and cellulose acetate is particularly preferred.

In addition, cellulose ester hollow fibers can be produced by conventionally known spinning methods, such as melt spinning, dry spinning, wet spinning, and semi-wet spinning, but they can be easily flattened by rolls, guides, and winding during the spinning process. It is particularly preferable that the fiber be produced by a wet spinning method or a semi-wet spinning method, which allows liquid to be injected into the hollow fibers to prevent the formation of the hollow fibers. Even if the hollow fibers contain plasticizers and additives, this does not deviate from the scope of the present invention. In particular, when manufacturing cellulose ester derivative hollow fibers by wet spinning or semi-wet spinning using an organic solvent with a high boiling point, it is possible to form a porous body on the easily obtained hollow fiber wall. It is not necessary to add any additives to the spinning dope in the sense of forming .

In addition, when using the wet method or semi-wet method, liquid can be injected into the hollow fiber due to its characteristics, and the yarn direction can be changed by guides during the spinning process, without causing flattening of the hollow part during stretching between rollers. Since it can be easily passed through the spinning process, there is no deterioration in fiber performance. Further, there are great advantages in carrying out the present invention, particularly in employing the spinning method, as the stretching and drying process can be carried out very easily without flattening. In order to produce regenerated cellulose hollow fibers from cellulose ester hollow fibers by the method of the present invention, it is necessary to deacylate the hollow fibers, a so-called saponification reaction, but this reaction is generally carried out in an aqueous caustic solution. is preferable.

At this time, for the purpose of controlling the saponification reaction rate or membrane performance, a salt of the same metal as the metal constituting the caustic alkali may be added to the saponification solution to perform the saponification reaction, or an alcohol, etc. It is also possible to coexist and saponify. In the present invention, the regenerated cellulose hollow fibers obtained in this manner are thoroughly washed with water, and then, if necessary, subjected to a known plasticizing treatment, that is, immersed in an aqueous glycerin solution, and then treated with air or heat at a temperature of 50°C or higher. It is an essential requirement that the film be dried in a stretched state in an inert gas.

The hollow fibers of the present invention obtained by drying the stretched state as described above can be obtained by drying the hollow fiber bundles, assembling them into modules, and sterilizing them. The dimensional stability is very good, and the elongation rate can be kept to 1.0% or less, which effectively prevents the fibers from folding or bending due to fiber elongation within the module. Channeling can be prevented and substances can be separated efficiently.

Note that drying in a stretched state means drying after stretching or stretching and drying at the same time. Hollow fibers that have been developed so far have been stretched to improve their morphological stability, which increases the degree of membrane orientation, resulting in a dense membrane structure and good permeation performance. However, in the present invention, stretching is not performed in the manufacturing process of the hollow fibers used as raw materials, or even if stretching is performed, the densification of the membrane structure is not promoted. Therefore, the membrane structure of the raw material fibers does not become dense, and the permeation performance of the obtained fibers does not deteriorate.

In addition, the purpose of improving the shape stability of hollow fibers is achieved by stretching the hollow fibers after washing with water for saponification. The hollow fibers obtained by the present invention have good permeability and good shape stability because they can be formed into perfect circular shapes by applying this stretching and drying process. This is possible. The drying temperature of the hollow fibers in carrying out the present invention is 50°C or higher, preferably 80 to 200°C in air or inert gas, and the stretching ratio is 0.1 to 10%. .

If the temperature in the drying process is less than 50°C, the hollow fibers cannot be sufficiently dried; on the other hand, if the drying temperature is 200°C
If the temperature exceeds that level, changes in the membrane structure may occur, making it difficult to consistently produce hollow fibers with good performance. In addition, as the drying atmosphere for the hollow fibers, in addition to air, inert gas, etc., drying methods such as a hot roller can also be used, but when adopting these mechanical drying methods, changes in the membrane structure,
Since the morphological stability may deteriorate, it is preferable to use air or an inert gas as the drying atmosphere. In addition, the stretching ratio during drying is preferably in the range of 0.1 to 10%; if the stretching ratio is less than 0.1%, the shape stability of the hollow fibers obtained may be insufficient; If it exceeds 10%, it is not preferable because structural defects such as pinholes may occur in the wall membrane of the hollow fibers obtained, and process troubles such as thread breakage may occur. In carrying out the present invention, since the hollow fibers are likely to flatten during stretching and drying, it is preferable to carry out the process with a liquid filled inside the hollow fibers. Since the fibers obtained by the method of the present invention have a small difference in elongation between dry and wet conditions, there is no need to perform plasticization treatment to suppress elongation during washing before module assembly, and dry sterilization is possible. , its transportability and cleaning properties during use have been significantly improved.

The present invention will be explained in more detail with reference to Examples below.

Example 1 27 parts of cellulose acetate with a degree of acetylation of 55% was dissolved in 67 parts of dimethylformamide and 6 parts of water at 90° C. over 1.511 hours, thoroughly defoamed and filtered to obtain a spinning stock solution.

This spinning stock solution was heated to 60°C, and 4.8 mL/min was added to the outer annular slit of a spinning nozzle having a double tube structure, and 3.5 m of octyl acetate was added to the inner tube of the spinning nozzle.
The hollow stock solution that passed through the nozzle was allowed to fall 7 cm into the air, and then introduced into a 3% dimethylformamide aqueous solution kept at 15°C and solidified.
It was rolled up at a speed of 7 TL' and thoroughly washed with water. The obtained cellulose acetate hollow fibers were immersed in a 3% by weight caustic sorter aqueous solution at room temperature for 3 hours, thoroughly washed with water, treated with a 5% by weight glycerin aqueous solution, stretched 3% and dried at 90°C for 3 minutes.

The obtained regenerated cellulose hollow fibers had a substantially perfect circular shape with an outer diameter of 335μ and an inner diameter of 295μ. When the hollow part was sufficiently washed with ethanol and the dried thread was soaked in water, the elongation rate was 0.3%, and the fiber arrangement was stable even when washed with water after the module was assembled. There are no holes and the water permeation rate is 3.7 (MlId, hr, wtHg),
The hollow fibers had dialysis performance that could sufficiently permeate urea and creanitine and sufficiently block the permeation of albumin.・Comparative Example 1 The same procedure was followed as in Example 1, except that the hollow fibers treated with glycerin after saponification and water washing in Example 1 were dried in three powders at 90°C with a fixed length or with no tension at all. The dry and wet elongation of two types of regenerated celluloid loins produced under the following conditions were as follows.

Drying at constant elongation length: 4.7% No tension: 5.9% When these hollow fibers were washed with water after assembly of the module, the fibers were significantly bent and folded, making them completely useless.

Example 2 25 parts of cellulose acetate with a degree of acetylation of 52.5%, 65 parts of dimethyl sulfoxide, 2 parts of magnesium perchlorate,
8 parts of water was dissolved at 85° C. over 2 hours, and the mixture was thoroughly degassed to obtain a spinning stock solution.

This spinning stock solution was heated to 50°C, and 4.8 mL of n-butanol was fed into the outer annular slit of the spinning nozzle having a double tube structure at a rate of 4.8 mL.
The hollow stock solution that passed through the nozzle was dropped 10 cm into the air at a temperature of 40°C maintained at 20°C.
% dimethyl sulfoxide aqueous solution and solidify it.
It was taken off at a speed of 0 mI, then washed through hot water at 70°C, and at the same time stretched 1.3 times to 39771. No Min
It rolled over at a fast pace. After thoroughly washing the hollow fibers with water, they were placed in an aqueous solution of 15% by weight of sodium sulfate and 3% by weight of caustic soda at 9°C.
Saponification was performed at 0°C for 1 minute. After that, wash thoroughly with water and continue with step 2.
It was treated with a glycerin aqueous solution of % by weight. The regenerated cellulose hollow fibers were dried at 130° C. while being stretched by 4% between rollers (roller speed 10-10.4 Tr 1.1 min).

The obtained cellulose acetate hollow fiber has an outer diameter of 280μ
, and had an almost perfect circular shape with an inner diameter of 240μ.

After thoroughly cleaning the hollow part with an aqueous ethanol solution, dry it.
When the dried hollow fibers are immersed in water, the elongation rate is 0.1. Therefore, the fibers are washed and dried, and after module assembly, dry sterilization is performed to ensure that the fiber arrangement is stable without deterioration when washed with water during actual use. Was. Further, there were no pinholes and the water permeation rate was 2.5 (Mllrfl, hr, TfrmHg), and urea and creanitine were sufficiently permeated, but albumin was almost completely blocked. The flattening of the hollow part that occurred during saponification completely disappears after drying. - It was restored to a perfect circular shape.

Example 3 25 parts of cellulose acetate with a degree of acetylation of 55% was added to 66 parts of dimethylacetamide, 6 parts of zinc chloride, and 3 parts of water at 110°C.
The mixture was stirred and dissolved for 1 hour, and thoroughly defoamed and filtered to obtain a stock solution for spinning.

This spinning stock solution was heated to 70°C, and the rate of 4.5 ml/min was applied to the outer annular slit part of the spinning nozzle having a double-tube structure, and the isopropyl myristate was applied to the inner pipe part of the spinning nozzle at a rate of 2.0 ml/min. The stock solution was supplied at a rate of 30 TrLI to form a hollow stock solution that was allowed to fall 5.0 cm in the air, then introduced into a 30% dimethylacetamide aqueous solution kept at 10°C to solidify, and then taken out at a rate of 30 TrLI, and then submerged in water at 30°C. The film was stretched 1.3 times and rolled up at a speed of 397 nI.
After thorough washing with water, the hollow fibers were continuously released at a rate of 4w1,1 minutes and introduced into an aqueous solution of 3% by weight of sodium acetate and 3% by weight of caustic soda at 90°C for a residence time of 30 seconds. Subsequently, it was washed with hot water at 90°C, placed in a 15% by weight aqueous glycerin solution, and then continuously stretched by 2.5% while being placed in a dryer with a length of 2 TrL maintained at 150°C for drying.

The obtained regenerated cellulose hollow fibers had a substantially perfect circular shape with an outer diameter of 255 μm and an inner diameter of 210 μm, and had almost no unevenness in cross-section.

When the hollow part was sufficiently washed with ethanol, dried, and immersed in water again, the elongation rate was 0.4%, and the fibers did not sag when washed with water after module assembly, indicating that it could be used as a good module.

There are no pinholes and the water permeation rate is 3.1 (Mllrrl, h
r, m! Hg), urea and creanitine were sufficiently permeated, but albumin was almost completely blocked from permeating.

Example 4 23 parts of cellulose acetate with a degree of acetylation of 55%, 63 parts of dimethylacetamide, w parts of zinc chloride, and 4 parts of water were heated at 100°C.
The mixture was mixed, stirred and dissolved, and thoroughly degassed and filtered to obtain a spinning stock solution.

This spinning stock solution was heated to 70°C, and liquid paraffin was poured into the outer pipe annular slit part of the spinning nozzle having a double pipe structure at a rate of 5.0 m1I, and liquid paraffin was poured into the inner pipe part of the spinning nozzle at a rate of 2.6 m1I.
357TL. It was taken off at a speed of 1 minute and shaken into a can containing a 2% aqueous solution of caustic soda at room temperature. 1
After saponifying for an hour, it was thoroughly washed with water, treated with a 1% glycerin aqueous solution, and then passed through a dryer at 170°C at a feed rate of 5m. The film was passed through at a winding speed of 5.5 rmin, ie, stretching was applied at 10%.

The obtained regenerated cellulose hollow fibers had an approximately perfect circular shape with an outer diameter of 315 μm and an inner diameter of 274 μm, and almost no irregularities were observed in the cross-sectional shape. After thoroughly washing the inside of the hollow fiber with benzene and alcohol and drying it, the lengthwise elongation of the fiber was 0.1% when it was returned to a wet state, and it has been used as a good module.

Claims (1)

[Claims] 1. When producing regenerated cellulose hollow fibers by substantially deacylating cellulose ester hollow fibers, the regenerated cellulose hollow fibers in a wet state after deacylation are heated in air or inert gas at 50°C or higher. A method for producing regenerated cellulose hollow fibers, which comprises drying in a stretched state. 2. The method for producing regenerated cellulose hollow fibers according to claim 1, wherein the cellulose ester hollow fibers are made of cellulose acetate. 3. The regenerated cellulose hollow fibers according to claim 1, characterized in that the cellulose ester hollow fibers are hollow fibers produced by wet spinning or semi-wet spinning a spinning dope in which cellulose ester is dissolved in an organic solvent. Fiber manufacturing method. 4. The method for producing regenerated cellulose hollow fibers according to claim 1, characterized in that the stretching method uses conditions such that the stretching ratio is in the range of 0.1 to 10%.