JPS62162009A - Viscose rayon hollow fiber - Google Patents

Abstract

PURPOSE:The titled hollow fiber that is composed of regenerated cellulosic fibers made through the viscose rayon process and has the skin layer of a specific thickness as the outer wall, the core layer as the inner wall and the running-through hollow part, thus showing good mechanical properties, high dimensional stability and excellent membrane permeation performance. CONSTITUTION:The objective hollow fiber is composed of a thin skin layer less than 1mu thick as the outer wall, a core layer as the inner wall and a running-through hollow part, and is made from regenerated cellulose through the viscose rayon process. When the outer diameter of the hollow fiber is represented as amu, the wall thickness as bmu, a and b preferably satisfy following equations: 50<=a<=500, and 1.33X10<-2>a+2.33<=b<=6.67X10<2>a+6.67<=30.

Description

[Detailed Description of the Invention] (Field of Industrial Application) In recent years, research on membrane separation technology as a means of separating ions, low-molecular substances, and microparticles has been actively conducted. A method has been developed in which a ring-shaped fiber wall is used as a separation membrane.

The present invention relates to a tubular hollow fiber made of regenerated cellulose produced by a viscose process and used for the above purpose.

(Prior Art) Typical methods for producing hollow fibers using viscose rayon include (1) a method using a viscose stock solution to which a blowing agent such as an inorganic carbonate is added; (2) A method of continuously blowing gas using a special spinneret.

(3) A method of adhering immediately after spinning using a horseshoe-shaped spinneret. (4) There are methods such as using a double spinneret to continuously extrude the hollow agent into the center of the raw solution discharge flow, but (1) ~
The hollow fiber obtained by method (3) cannot be used as a separation membrane because it is difficult to stably obtain a hollow part that penetrates the entire length of the fiber, and there are 6D, pinholes, and uneven membrane thickness. Currently, it is mainly used for clothing or paper. Hollow fibers produced by method (4) can be used as separation membranes, but in either case, a method is used in which the viscose stock solution is directly extruded into a spinning bath and then spun. However, in this spinning method in which the viscose stock solution is directly extruded into the spinning bath, stable spinning is not possible unless the spinning draft is adjusted to a range of 0.5 to 2.5, so a spinneret with extremely high precision must be used. Alternatively, it was necessary to spin at an extremely low spinning speed.

Otherwise, it was necessary to perform multi-bath high tension in a semi-solidified state.

Furthermore, since the regeneration reaction of viscose rayon involves the elimination of the xanthate group of cellulose xanthate, gases such as carbon disulfide and hydrogen sulfide are generated at this time. When hiring,
Generally speaking, the surface of the spinneret from which the viscose stock solution is extruded is upward or lateral.% It is not possible to reduce the resistance of the spinning bath, and the wall thickness of the hollow fibers may be thinned and the wall thickness may be made uniform. In addition, it was not possible to obtain a hollow fiber with high winding speed, and it was not possible to increase the winding speed.

In addition, rayon hollow fibers produced using the usual viscose rayon yarn spinning method and spinning bath composition can be obtained with a thick skin layer on the outer wall surface layer, but when the skin layer is thick, the skin layer and core layer Due to the difference in shrinkage rate and the moisture in the viscose in the semi-solidified state seeping out of the filament, only hollow fibers with severe unevenness on the surface can be obtained. The circular cross-sectional shape is poorly maintained, and only hollow fibers with extremely irregular cross-sectional shapes in the fiber length direction can be obtained. Furthermore, even if the composition of the spinning bath is changed and yarns are formed by only coagulating in a salt bath, this does not require an extremely long immersion length in the spinning bath, and production can only be carried out at an extremely low winding speed. If stretching is not performed after coagulation, hollow fibers with almost no skin layer can be obtained, but their strength is low and they cannot be used as separation membranes in practice. In addition, if high stretching is performed after solidification, a strong hollow fiber with an extremely thick skin layer can be obtained, but the membrane permeation resistance is large and the membrane permeation performance is extremely low.
It has many pinholes and is not suitable for industrial manufacturing.

Among the above-mentioned conventional techniques, a method for manufacturing viscose rayon hollow fibers for membrane separation has recently been proposed, for example, in East German Patent No. 131941, but this method uses a viscose stock solution extruded from a spinneret. Hollow fibers are produced by direct coagulation in a spinning bath and then stretching in a long bath, but the resulting hollow fibers cannot achieve both membrane strength and permeation performance, and the winding speed is low. 3
It was required that the spinneret be extremely small, 0%/min or less, and that the precision of the spinneret be extremely high, which was disadvantageous in terms of industrial production.

(Problem to be Solved by the Invention) A hollow fiber has a hollow part that is completely penetrated over the entire length of the fiber in order to pass the liquid or gas to be separated or the separated liquid or gas. It is essential that the reeds and the front wall forming the hollow part have no partial defects and must have a physical strength to the extent necessary for the separation process. In order to obtain even better separation performance, it is necessary that the hollow fiber walls be uniform over the entire fiber length and as thin as possible.

The present invention addresses the drawbacks of the conventional technology of viscose rayon hollow fibers, such as poor circularity retention of hollow fibers, pinholes and uneven film thickness, and insufficient compatibility between strength and membrane permeability. The purpose of this invention is to provide a viscose rayon hollow fiber suitable as a separation membrane by eliminating all disadvantages in separation applications.

Furthermore, in the conventional technology, it was difficult to eliminate unevenness with thin viscose rayon hollow fibers having a film thickness of 30 μm or less. For this reason, various attempts have been made to eliminate unevenness in viscose rayon hollow fibers, which have a normal two-layer structure. I couldn't get the thread.

(Means for Solving the Problems) As mentioned above, the present inventors have developed a viscose film that can be used for membrane separation with a film thickness of 30 μm or less and with no irregularities on the surface, which was difficult to achieve with the conventional technology. The purpose is to obtain rayon hollow fibers. As a result of analyzing the structure and properties of the skin layer of the hollow fiber, which has a two-layer skin/core structure that is typical of viscose rayon yarn, and conducting intensive research into its formation process and its role as a separation membrane, the skin layer It was found that the thickness of the membrane influences the size of the surface irregularities and the circularity of the cross section, and also influences the membrane permeation performance and membrane strength.

As a result, the outer wall has an extremely thin skin layer of 1μ or less, has no severe irregularities on the outer wall surface layer, maintains a stable circular shape when dry or wet, and has an extremely thin wall thickness of 30μ or more. Viscose rayon hollow fibers having uniform reeds, wall thicknesses, and diameters over the entire fiber length were obtained.

This makes it possible to suppress a decline in membrane permeation performance while maintaining the strength necessary for membrane separation.

In hollow fibers with a thick skin layer, stress is generated and deformed when drying and wetting due to the difference in swelling degree, shrinkage rate, and orientation between the skin layer and the core layer, resulting in hard unevenness on the outer wall surface layer. However, by reducing the skin layer formed on the surface layer to 1 μm or less, this deformation could be prevented and a hollow fiber having a uniform circular shape and wall thickness over the entire fiber length could be obtained.

The hollow fiber according to the present invention is a hollow fiber made of regenerated cellulose fiber using a viscose process, and is characterized in that the hollow fiber has a skin layer of 1.0μ or less on the surface layer of its outer wall in the longitudinal direction of the gold thread and over the entire circumference. There is. Further, the preferred dimensions and shape of the hollow fiber are such that over the entire length and circumference of the hollow fiber, where the outer diameter of the hollow fiber is aμ and the wall thickness is bμ, the range is 5≦a≦500 and 1.33+10 2a+2.33
≦b≦6.67X102a+6J7≦30 If the range is within this range, the circular shape can be stably maintained both when dry and when wet.

The viscose stock solution used in the present invention is produced from wood pulp, and contains alkali cellulose, carbon disulfide,
Contains caustic soda, preferably has a viscosity of 50-3
A stock solution of viscose with a 0.00 void and a ripeness Hz number of 1.5 to 4.0 is suitable.

In other words, viscose with low viscosity has low viscosity and 5
Using a stock solution of 0 poise or less and dropping it into space while filling it with a hollow agent will likely cause spinning to become unstable, and if a stock solution with a high ripeness Hz value is used, gases such as carbon disulfide will be generated due to decomposition. This is rapid and may cause voids and non-uniformity of shape in the hollow fiber membrane. In other words, it is desirable to use a viscose stock solution with a fast solidification rate, relatively slow regeneration, and a low ripeness Hz value.

The hollowing agent applied to the present invention must be a liquid substance that does not have a rapid coagulation effect on the viscose stock solution. When a hollow agent with a strong coagulation effect is used, a gel-like coagulum is produced when the inner layer of the hollow fiber is free-falling or the outer layer and inside the wall are not sufficiently coagulated in the spinning bath. The movement of gel-like substances occurs unevenly, and gases such as carbon disulfide and hydrogen sulfide are generated in the hollow part due to the decomposition of cellulose xanthate, and the resulting hollow fibers have many uneven diameters and pinholes. You can only get things. Furthermore, if a liquid that is compatible with water, such as water or its solution or a low-molecular-weight alcohol, is used as the hollowing agent, the hollowing agent may leach into the spinning bath and may be transferred to the outer surface of the hollow fiber during drying. As a result, the hollow agent moves and evaporates, and only hollow fibers with collapsed hollow portions or completely closed hollow fibers are obtained. Hollow agents suitable for the present invention include aromatic hydrocarbons (benzene, toluene, xylene,
ethylbenzene, cumene, styrene, etc.), aliphatic hydrocarbons (hexane, pentane, petroleum ether, liquid paraffin, etc.), or halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride, dichloroethylene,
Trichloroethylene, 7-chloroethylene, etc.), especially hollow agents (chloroform, 7-chloroethylene) having a large specific gravity and a boiling point higher than the spinning bath temperature.

The above-mentioned hollow fibers are produced by continuously extruding the viscose stock solution and the above-mentioned hollow agent simultaneously and continuously using a double spinneret with the hollow agent contained in the center, and then introducing the solution into a spinning bath where it is coagulated and regenerated to form a tubular hollow fiber. During the production process, the extruded viscose stock solution and hollow agent are once heated in a space of 10~100111
After 31 free fall, it is vertically introduced into the spinning bath at -10 = spinning draft 4.0 to 16.0 to solidify, and then as a processing method the formed filament is wound and taken up on a take-up frame. This is finally obtained through a water washing process, a neutralization process, a water washing process, and a drying process. Alternatively, it can be obtained by continuously passing through the above treatment steps as another treatment method.

Here, the lower surface of the double spinneret is heated to 40 to 70°C, for example, an electric heater is built into the lower surface of the spinneret, and the spinneret is heated to produce a viscose stock solution produced by one drop of water due to the coagulation of evaporated water from the spinning bath. Stable operation is possible because flat flow and liquid shortage can be prevented.

Furthermore, it is easiest and usually preferable that the atmosphere in this space be in the air.

During free fall in space, the viscose stock solution continuously contains hollow agents inside it, and is in the form of a liquid that can flow when falling in space, and the falling speed is low because the viscosity of the viscose stock solution is low. quickly increases in size, and by passing through a small space, the stock solution is sufficiently stretched, and by the time it reaches the spinning bath surface, it can be reduced to a sufficiently small size that is almost the same as the diameter of the hollow fiber. . In other words, when immersed in a diameter spinning bath, the surface is stretched in a semi-solidified state, so
A thick skin layer oriented in the yarn length direction is generated, but by providing a spatial fall region, the viscose stock solution has a sufficiently thin linear shape in its liquid state, so this skin layer can be made thinner. be able to. Furthermore, surface tension forces allow the wall thickness to be uniform over the entire thread length and circumference.

The lower limit of the size of this space is regulated by the falling speed on the surface of the spinning bath, and the upper limit is regulated by the spinning performance of the viscose stock solution, and the appropriate range is 10 to 100 wx. If the spinneret is less than 10 mm, the spinning tension directly affects the spinneret, and even if the spinneret is strictly horizontally positioned, spinning cannot be performed at a winding speed of 30 minutes or more. When the winding speed is further increased, the state in which the hollow agent is partially contained by the raw viscose solution is destroyed, many pinholes are generated, and the membrane does not function as a separation membrane. In addition, the water vapor from the spinning bath is deposited on the spinneret and coagulated tightly, and wall thickness unevenness occurs in the area where the coagulated water droplets come into contact with the viscose raw solution stream, resulting in loss of uniformity.

When the space is 100 nm or more, the stringability of the viscose stock solution is lost and it is no longer possible to obtain hollow fibers having a uniform diameter and wall thickness in the entire fiber length direction. Furthermore, if the size is extremely large, the surface tension results in a chip-like shape containing a hollow agent in the center, or even a continuous thread-like shape. Therefore, when manufacturing viscose rayon hollow fibers, if the space length is set in the range of 10 to 10 am and the position is appropriate for the winding speed and extrusion amount of the stock solution, it is possible to produce hollow fibers with an extremely stable shape. It can be manufactured. As shown in Examples 1 to 3 below, the winding speed is 80 to 1.
Viscose rayon hollow fibers having stable shape and membrane performance even at high speeds of 50 m/min are obtained. As for Df, as shown in Table 5 of Example 6, it is 5.6~
It was carried out in a range of 14.

The optimum size of the spinneret varies depending on the dimensions of the hollow fiber, winding speed, space length, etc., but the preferable Df is 4 to 1.
The range is 6. Here, Df is the winding speed/the linear velocity of male scose discharge, and although it is not the draft value at the true spinneret surface, it is a measure for evaluating the influence on the dimensional accuracy of the spinneret. Although spinning is possible even in a small region of less than Df4, it is necessary to set the space length short, and the agglomeration of water vapor from the spinning bath to the spinneret becomes severe, and the precision of the spinning nozzle must be extremely high. Otherwise, it will be difficult to obtain circular hollow fibers with few wall thickness irregularities. In a region where Df exceeds 16, even if the space length is set short, the stringability of viscose is lost, making it difficult to obtain hollow fibers with a uniform diameter and wall thickness in the yarn length direction. At the same time, pinholes occur frequently.

Furthermore, in order to prevent unevenness or cut threads due to adhesion of water droplets and to achieve stable continuous operation performance, it is desirable to heat the bottom surface of the spinneret to 40 to 70°C. When a spinning bath is used, adhesion of water droplets can be prevented, and stable continuous spinning can be performed for a long period of time.

The distance of the vertically running portion in the spinning bath is preferably about 30 to 150 m, and bath resistance can be reduced by forming the vertically running portion as a flow tube. In particular, when the speed of the spinning solution in the flow tube is lower than the winding speed (actually, almost equal to the thread running speed in the flow tube), very stable operation can be achieved.

The winding speed at this time is preferably 65 to 150 m/min.

As the spinning bath, a spinning bath whose composition is usually rayon yarn can be used. Tsumashi sulfuric acid 50-200E/l-
Sodium sulfate 100-3sOF/l, zinc sulfate 20
An aqueous solution containing sulfuric acid of 120 to 1
609/l, sodium sulfate 200-3-00 l/l
It is desirable to use an aqueous solution containing 5 to 15 g/l of zinc sulfate. Further, it is desirable that the spinning bath temperature is relatively low in the range of 30 to 50°C. The speed of regeneration of the pick is made relatively slow, and at the same time, the generation of gases such as carbon disulfide and hydrogen sulfide due to decomposition is made slow, thereby preventing the generation of zeids and pinholes. Furthermore, when spinning at a high spinning bath temperature, a large amount of gas such as carbon disulfide and hydrogen sulfide is generated due to the rapid decomposition of cellulose xanthate, which causes zeids, pinholes, and diameter unevenness in the cross section of the hollow fiber. occurs frequently.

Regarding the process of vertically downward immersion in the spinning bath, the distance is preferably 30 to 150 eM. j) When using an immersion length of 30 cIn or less and changing the running method of the yarn by changing the yarn path, the hollow fibers may not be sufficiently coagulated on the outer layer surface and inside the inner layer wall, and may not be subjected to physical pressure. When exposed to such stress, the hollow fibers may be deformed, resulting in hollow fibers that are flat or have uneven wall thickness, which is a major factor in the generation of pinholes in the hollow fibers. 15
If the immersion length is 0 crn or more, the spinning bath resistance will be large, and furthermore, it is unfavorable from the viewpoint of operability in production.

In particular, the vertical immersion part mentioned above is used as a flow tube, and the flow tube length is 30 mm.
It is preferable that the flow velocity in the λ tube is less than or equal to the winding speed. By controlling the flow rate in the pick flow tube and reducing the resistance to the yarn by the spinning bath, hollow fibers with extremely thin wall thickness can be stably produced. Furthermore, if the flow velocity in the flow tube is made higher than the winding speed at the flow tube outlet, breakage may occur in the space fall region, making stable production difficult. Furthermore, as the flow rate approaches the winding speed, stretching due to bath resistance is reduced, and the thickness of the skin layer on the surface of the membrane can be reduced. Further, depending on the size of the hollow fiber, it is desirable to provide a horizontal dipping tank immediately after the vertical dipping tank as necessary to complete sufficient coagulation. FIG. 2 shows an enlarged cross-sectional shape of the viscose rayon hollow fiber of the present invention obtained by the above manufacturing method, and FIG. 3 shows an electron micrograph (30,000 times magnification) thereof. The wall thickness surrounding the hollow part of the hollow fiber is thin and uniform, and the wall components are skin,
It has a two-layer core structure, and has a skin layer portion on the outer wall surface layer of the core in a range of 1.0 μm or less. For hollow fibers with a thick skin layer, it is necessary to use a viscose stock solution with a high ripeness Hz number, perform high stretching in the spinning bath, increase the spinning bath temperature, or increase the zinc sulfate concentration in the spinning bath to 20971 or higher. However, such hollow fibers with a thick skin layer have a cross-sectional shape with severe irregularities on the outer wall surface layer due to the difference in shrinkage rate between the skin part and the core part. This results in irregularities in cross-sectional shape and wall thickness.

In addition, there are many pinholes caused by the generated gas, and the passage resistance in terms of membrane separation performance is large, making it impossible to obtain a product that can be put to practical use.

When the outer diameter of the hollow fiber obtained by this method is set to 50 μm or more, it is possible to reliably obtain a hollow fiber in which the hollow portion of the hollow fiber penetrates uniformly, and the hollow fiber has a uniform wall thickness. As a result, cut yarns do not occur and stable spinning can be performed for a long time. Further, it is possible to manufacture hollow fibers with an outer diameter of 500 μm or more by changing the spinneret. However, if the thickness is 500μ or less, the hollow portion will not be crushed or flattened due to the winding frame and the changed yarn path. In addition, it is possible to prevent the formation of hollow fibers that are in close contact with departments and public offices. Further, if the wall thickness of the hollow fiber obtained by the present invention is 3μ or more, the hollow fiber can withstand spinning bath resistance and changing yarn path or physical pressure on the winding frame. can be obtained stably. Further, in order to manufacture a product with a large wall thickness of 30 μm or more, a vertical immersion length of several meters is required, and after that, a horizontal immersion length of the same length can be adopted. But 30
μ or less, if the vertical immersion part is 150 crn or less, the yarn can be sufficiently coagulated, and it is advantageous to use one pole as a practical production process, and the bath resistance is small and the outer wall A thin hollow fiber with a surface skin layer is obtained.

By this production method, it is possible to produce rayon hollow fibers with very stable dimensions, usually depending on the composition of the rayon spinning bath, by winding up tubular hollow fibers with extremely thin wall thickness at a high winding speed of 60 to 150 m/min.

(Effects of the Invention) The rayon hollow fiber of the present invention has a smooth surface with almost no irregularities on both the outer and inner walls. Furthermore, since the skin layer can be obtained in an extremely thin and uniform thickness, it is possible to improve separation performance and make the film thinner than conventional viscose rayon hollow fibers. Furthermore, the rayon hollow fiber of the present invention is a hollow fiber that has both the two contradictory properties of the conventional viscose rayon hollow fiber, which has sufficient strength against compression and bending, and has sufficient separation performance.

As detailed above, the hollow fiber according to the present invention has a special cross-sectional structure as a viscose rayon hollow fiber.
The mechanical stability, dimensional stability, and membrane permeation performance are superior to conventional viscose rayon hollow fibers, making it useful as a substance separation membrane, and particularly suitable as a reverse osmosis membrane or a dialysis membrane. .

Example 1 A manufacturing method for obtaining the hollow fiber of the present invention will be briefly explained using FIG. 1. A fixed amount of the stock solution and hollow agent are sent to the double spinneret 3 from a spinning stock solution tank 1 and a hollow agent layer tank 4 via a gap pump 2 and a metering pump 5.

The annular outer diameter of the double spinneret 3 is 0.7B and the inner diameter is 0.51!
The stock solution is extruded through the slit Im, and the hollow agent is extruded through the hole with a diameter of 0.2 rxx in the center. 6 directly below the double spinneret 3
Flow tubes 10 having a diameter of 301 m and a length of 40 c11t are arranged with a space of 0 m between them.

This flow tube 10 has an overflow set, so that the spinning solution sent from the inlet fills the inside of the flow tube 10 and falls freely, passes through the constriction at the bottom of the flow tube 10, and passes through the horizontal immersion bath 12.
flows into. The flow rate of the spinning solution in the flow tube 10 is determined by the length of the flow tube (more precisely, the distance between the head and the immersion bath surface) and the diameter of the orifice. In this example, the spinning bath flow rate was 80 m/min while the winding speed was ixom/min.

The hollow agent pushed out from the spinneret 3 and the spinning dope surrounding it fall freely to the center of the flow tube 10, travel vertically downward in the flow tube 10, and are directed by the guide 7 located 50 cIm below the bath surface. It is turned around and runs horizontally through the horizontal immersion bath, passing through the guide 8.9 and being wound onto the winding frame 13. The distance through which the hollow fiber passes through the immersion bath is 100 cm. Now, the cellulose concentration was adjusted by a known method: 8.51% Caustic soda concentration: 6
．． Hollow fibers were produced by the apparatus and method described above using a viscose rayon spinning dope having a ratio of 0, Hz number 3.1 and a viscosity of 150 poise and A-chloroethylene as a hollowing agent. The spinning bath composition was 1409/l of sulfuric acid and 10/l of zinc sulfate.
9/l, 26097 g of sodium sulfate, and the bath temperature was 40°C. The yarn wound on the winding frame was removed from the winding frame, thoroughly washed with water in a shower, neutralized with 2 g/l of caustic soda, and further washed with water. The obtained material was hung on a general frame and dried by passing it through a tunnel dryer while pulling out the filament. The temperature inside the dryer was adjusted to 120'CK. After drying, cut the whole
After leaving it indoors for several hours and recovering the hollow agent filled in the hollow part, the hollow agent was removed by vacuum degassing. The hollow fiber thus obtained had an outer diameter of 235μ and a cross-sectional wall thickness of 1
It was 3μ. The wall thickness was uniform in the entire fiber length direction and in the entire cross-sectional direction, with no unevenness, and the cross-sectional shape was close to circular and no irregularities were observed on the surface. When this hollow fiber was moistened and its cross section was observed under an electron microscope at a magnification of 30,000 times, it was confirmed that there was a skin layer with a thickness of 0.9 μm on the outer wall surface layer. As shown in Table 6, the obtained hollow fibers exhibited good performance as a separation membrane.

An enlarged cross-sectional photograph of the hollow fiber at this time is shown in FIG. 2, and an electron microscope photograph is shown in FIG.

Example 2 According to the spinning method described in Example 1, spinning was carried out by varying the spatial fall length and varying the falling speed of the viscose stock solution flow onto the spinning solution surface. The results are shown in Table 1. From this table, in the method of the present invention, the spatial free fall range is 10 to 100.
It turns out that IolE is appropriate. For comparison, an experiment was also conducted in which the spinneret was immersed in the spinning solution.

Table 1 Influence of Spatial Free Fall Region Example 3 Table 2 shows the results of spinning with various lengths of the vertical traveling portion of the spinning stock solution flow in the spinning bath. From this result, the circular shape retention is good when the vertical immersion length is 30 m or more.

Table 2 Influence of Vertical Running Portion Example 4 Table 3 shows the results of spinning according to the spinning method described in Example 1 while varying the spinning solution speed in the vertical immersion zone.

These results show that spinning is impossible when the spinning solution speed exceeds the winding speed, and that the thickness of the skin layer of the obtained hollow fiber tends to become thinner as the spinning solution speed increases.

Table 3 with blank space below: Effect of spinning solution speed in flow tube Example 5 Winding speed 85 g according to the spinning method described in Example 1
Table 4 shows the results of spinning at 7 minutes with various extrusion amounts of the viscose stock solution and hollow agent. From this, the hollow fiber obtained by the present invention has an outer diameter of 50 to 5
00μ, and the relationship with the wall thickness is 1.33xxo-2x (outer diameter) + 2.33≦wall thickness (μ)≦6.67X10” x (outer diameter) + 6.77≦30. I understand.

All hollow fibers produced within this range showed good performance as separation membranes.

Table 4 with blank space below. Possible manufacturing range of hollow fiber Example 6 By changing the winding speed according to the method of Example 1, the outer diameter is 20.
Table 5 shows the results of producing hollow fibers with a wall thickness of 0μ and a wall thickness of 15μ. For comparison, the results of immersing the spinneret in the spinning bath are also shown. These results show that with this method, the winding speed can be much higher than in the case of bath immersion, the stability of the hollow fiber morphology has been improved, and the pore diameter of the spinneret can be increased, resulting in improved productivity. It can be seen that the above is extremely good.

Comparative Example 1 Hollow fibers were manufactured according to the method of Example 1. At this time, 109'/71 dilute sulfuric acid was used as the hollowing agent.

It was found that the hollow fibers obtained had collapsed hollow portions, many wall thickness spots, and severe unevenness on the outer wall surface layer, making it impossible to use them for dialysis.

Comparative Example 2 Hollow fibers having an outer diameter of 200 μm and a wall thickness of 15 μm were produced using a viscose stock solution with a maturity level and Hz value of 6.5 according to the method of Example 1. The obtained hollow fiber had a skin layer thickness of 1.5 μm, and the outer wall surface layer had some irregularities and unevenness in the inner diameter. The permeation performance of this hollow fiber was found to be poor as shown in Table 6.

Comparative Example 3 Cellulose concentration 8.5% adjusted by known method
, caustic soda concentration 6.0, Hz value 5.0, viscosity 70
The Boyes viscose stock solution was extruded directly into the spinning bath using a dual spinneret. At that time, the hollow agent Id A-chloroethylene was used, and the spinning bath contained ammonium sulfate at 2609
The temperature was 30° C., and the length of the immersion bath was 3 m. Subsequently, the yarn was passed through a 101# sulfuric acid bath at 30°C for 3 m, and then passed through a second drawing bath (10L
/A'.H, SO, temperature: 30° C., temperature: 1 m), and at that time, it was stretched by 10 times and wound up by a winding frame. The winding speed was 16 m/min. Thereafter, processing was carried out according to the post-processing method of Example 1 to obtain hollow fibers having an outer diameter of 200 μm and a wall thickness of 15 μm. The cross section of the obtained hollow fiber was approximately circular, and the thickness of the skin layer on the surface of the outer wall was 3 μm. Furthermore, the membrane permeation performance was found to be poor as shown in Table 6.

As shown in Table 6, the hollow fibers obtained in the examples of the present invention exhibit good permeation performance as dialysis membranes, and according to the method of the present invention, viscose can be used as such separation membranes. It has been found that rayon hollow fibers can be manufactured with extremely high productivity.

As a comparative example, the permeation performance of hollow fibers using the cupra ammonium method is shown.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus used to produce the hollow fiber of the present invention, and FIG. 2 is an enlarged cross-sectional photograph (225 Figure 3 is an electron micrograph showing the surface layer of the outer wall of the special button (30,000 times).
It is. The contents of the numbers in the diagram shown in FIG. 1 are as follows. 1...tank for spinning dope, 2...gear pump, 3...double spinneret, 4...
Hollow agent tank, 5...-metering pump, 6...
...Hollow fiber, 7,8.9...Guide, 10.
...Flow tube, 11...Spinning inlet, 12.
...--Horizontal immersion melting, 13... Winding frame, 14
・・・・・・Spinning bath. Patent applicant: Asahi Kasei Industries, Ltd. Procedural amendment (method) 1. Description of the case Patent Application No. 200081, filed in 1985, 2, Name of the invention: Viscose Rayon Hollow Fiber 3, Person making the amendment Relationship to the case Patent applicant: 1-2-6-4 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture, Amendment Date of order January 7, 1985 (62, 1, 27) 5, subject of amendment 6, content of amendment + 11 "Expansion showing embodiments" on page 32, lines 4 to 6 of the specification... ... Showing the surface layer of the outer wall" was replaced with "Enlarged photograph showing the fiber cross-sectional shape of the hollow fiber in the example (225
Figure 3 particularly shows the outer wall surface layer structure (upper part: skin layer, lower part: core layer) of the hollow fiber. (2) Figure 3 of the drawing is corrected as attached. that's all

Claims (1)

[Claims] 1. A hollow fiber made of viscose-processed regenerated cellulose fiber with continuous hollow parts, the hollow fiber is composed of two layers, a skin layer and a core layer, and the skin layer covers the outer wall, A viscose rayon hollow fiber 2 characterized in that the core layer forms an inner wall and the skin layer has a thickness of 1μ or less, where the outer diameter of the hollow fiber is aμ and the wall thickness is bμ. Range is 50≦a≦500 and 1.33×10^-^2a+
2.33≦b≦6.67×10^-^2a+6.67≦
30 and has a circular cross section, the viscose rayon hollow fiber according to claim 1.