JPS60261510A - Manufacture of laminated hollow yarn - Google Patents

Abstract

PURPOSE:To manufacture easily and economically the titled laminated hollow yarn capable of separating a gas efficiently and selectively by applying a melt- spinning system to a biconstituent thermoplastic crystalline high molecular material. CONSTITUTION:The manufacture consists of three steps. Namely, one component of a biconstituent thermoplastic crystalline high molecular material is firstly spinned to a hollow yarn, and the outer periphery of the hollow yarn is secondly coated with the other component of the high molecular material while spinning before the hollow yarn is wound up. Thirdly, fine pores are formed in the hollow yarn obtained by using a high molecular material for porous membranes or in its coated layer. Either the homogeneous layer or the porous membrane layer can be formed on each other.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a laminated hollow fiber that can efficiently and selectively separate gases.

<Prior Art> A method is known in which a semipermeable membrane is used to separate a specific gas component from a gas mixture. Gas separation methods using semipermeable membranes can be broadly classified into the following two methods. One method is to use a dense homogeneous membrane with almost no pores inside the membrane, and utilize the property that gases dissolve and diffuse into the homogeneous membrane and move from one side of the membrane to the other. This is a method of separating mixed gases based on differences in solubility and diffusion rate in membranes. Another method is to use a porous membrane, which takes advantage of the property that separation occurs due to the difference in mean free path of gas molecules as they diffuse through micropores in the membrane. . The homogeneous membrane has a high gas selective permeability, but when used alone, it has the disadvantage that the gas permeation rate is slow because it is formed to a certain thickness for strength reasons. On the other hand, porous membranes have a high gas permeation rate, but have a drawback of low selective permeation ability for gas and 1 body. Therefore, in order to combine the advantages of the homogeneous membrane and porous membrane, a method has been proposed in which a dense homogeneous membrane is formed on one side of a porous membrane to create a laminated semipermeable membrane, which is used for gas separation. There is.

However, the conventionally known laminated semipermeable membranes are usually produced by a manufacturing method in which a porous membrane is formed as a hollow fiber and a homogeneous membrane is provided thereon. The homogeneous membrane is produced using a wet method, a plasma polymerization method, or the like. The production of a homogeneous membrane by a wet method has the disadvantage that the process becomes complicated because drying is required. On the other hand, the production of homogeneous membranes using the ZoraPuma polymerization method requires large and expensive equipment.
As a result, it is not possible to economically produce a semipermeable membrane in the form of hollow fibers with a laminated structure.

Furthermore, when separating a specific gas component from a gas mixture using a laminated hollow fiber, it is said to be more efficient to use a reduced pressure type, that is, to apply a negative pressure to the gas to be separated. When using this reduced pressure type, it is preferable to create a negative pressure inside the hollow fiber, and for that purpose, a laminated hollow fiber with a homogeneous membrane inside (a laminated hollow fiber with the structure shown in Figure 2b described later)
Is required. However, the conventionally known manufacturing method (3) for laminated hollow fibers can only produce a laminated hollow fiber with a homogeneous membrane on the outside (a laminated hollow fiber having the structure shown in the second diagram below). Therefore, even if it is desired to carry out efficient vacuum type separation, it is currently difficult to obtain a laminated hollow fiber that is suitable for this purpose.

<Problems to be Solved by the Invention> As is clear from the above, the conventionally known manufacturing method of laminated hollow fibers has no choice but to use complicated processes or expensive equipment, resulting in high manufacturing costs. The problem is that the production of homogeneous membranes is always limited to the outside. The present invention solves these problems, allows laminated hollow fibers to be manufactured easily and economically, and forms a homogeneous membrane either on the outside or inside of the hollow fibers of a porous membrane as required. The purpose is to provide a manufacturing method that can.

<Means for Solving the Problems> As a result of intensive research to solve the above-mentioned problems, the present inventor, Gin, used a thermoplastic polymer material as a coating material for forming porous membranes and homogeneous membranes. The inventors have discovered that it is possible to continuously produce laminated hollow fibers by employing the melt spinning method of the specific step (4), and have arrived at the present invention.

That is, an object of the present invention is to provide a method for producing a laminated hollow fiber comprising a porous membrane and a homogeneous membrane using a two-component thermoplastic crystalline polymer material using a melt-spinning method, the method comprising: A step of spinning one of the components of the polymeric material to produce a hollow fiber, and before winding the hollow fiber, spinning the other component of the polymeric material to cover the outer periphery of the hollow fiber. This is achieved by a method for manufacturing a laminated hollow fiber using a melt spinning method, which is characterized by comprising the steps of: forming micropores in the hollow fiber or coating layer in which the polymeric material for porous membrane is used. be done. The term "component" here does not mean only a single type of component, such as polypropylene or polyethylene, but rather a mixture of two or more types, such as a copolymer of polypropylene and polyethylene, or a mixture of propylene and polystyrene. Thermoplastic polymeric materials may also be included.

The polymer material for the hollow fibers that is first spun and formed in the manufacturing method may be for porous membranes or for homogeneous membranes. In the former case, a homogeneous film is formed on the outside;
In the latter case, a laminated hollow fiber with a homogeneous membrane formed inside is manufactured.

If the manufacturing method of the present invention is used, one component is melt-spun to produce a hollow fiber, and before the hollow fiber is wound, the other component is melt-spun to cover the hollow fiber, so it is continuous at one spinning station. A laminated hollow fiber can be manufactured by doing this.

The melt-spinning method is a method used to produce thermoplastic synthetic fibers, and generally involves a spinning process in which a thermoplastic synthetic resin material is melted and extruded through a nozzle to form a thread form. Furthermore, it does not include a drawing step of drawing to obtain a predetermined final yarn quality, and a step of collecting the yarn such as winding it onto a yarn arm or the like. However, when producing yarn for a specific purpose, the above-mentioned drawing step may be omitted. The melt spinning method as used herein refers to the fiber manufacturing method in the broadest sense as described above.

Various embodiments can be used as the step of forming micropores in the hollow fiber or coating layer in which the porous membrane polymer material is used.

For example, after a two-step spinning process, the yarn in which the two-component polymeric material is laminated is drawn, thereby creating micropores in the hollow fiber or coating layer in which the porous membrane polymeric material is used. may be formed.

In this case, it is desirable to use a polymer material for the homogeneous membrane that has, in the form of hollow fibers in a laminated structure, a breaking elongation equal to or higher than the stretching ratio applied here. However, when multiple micropores are formed in the polymer material for porous membranes, there is no practical problem even if some micropores are formed in the homogeneous membrane, for example, multiple micropores with an aperture ratio of 10q6 or less. .

Alternatively, a step of mixing a polymeric blowing agent into the polymeric material for the porous membrane at an arbitrary ratio may be provided, and a plurality of micropores may be formed by the blowing agent during melt spinning.

In this case as well, hollow fibers are usually manufactured using a porous membrane polymer material, but a porous membrane polymer material may also be used on the coating layer side.

Furthermore, at the same spinning station, after the step of spinning the porous membrane polymeric material to produce hollow fibers, the hollow fibers are drawn, thereby forming a plurality of micropores, and then the hollow fibers are drawn. A homogeneous membrane polymeric material may be spun to cover the outer periphery of the hollow fibers before winding them up.

The present invention will be described in further detail below with reference to the accompanying drawings.

FIG. 2a shows a longitudinal cross-sectional view of a hollow fiber 1 having a conventionally known laminated structure. That is, this laminated hollow fiber 1 has a hollow part 4 in the center.
A coating layer 3 made of a homogeneous membrane is provided on the outer periphery of a hollow fiber 2 made of a porous membrane having a laminate type hollow fiber having the structure shown in FIG. It is possible to manufacture any of the laminated hollow fibers having the structure shown in FIG. 2b, that is, a hollow fiber 3 made of a homogeneous membrane on the inside, and a grown stone coating layer 2 made of a porous membrane provided on the outer periphery of the hollow fiber 3. . Which type of laminated hollow fibers to use may be arbitrarily selected depending on, for example, the type of membrane module (see FIG. 5) to be described later, once these laminated hollow fibers are used.

FIG. 3 shows an example of an enlarged cross-sectional view of a laminated hollow fiber manufactured by the manufacturing method according to the present invention. As shown in FIG. 3, in the laminated hollow fiber, the porous membrane 31 is relatively thick and has a plurality of micropores 32 in order to maintain the physical strength of the hollow fiber. A relatively thin homogeneous membrane 33 is placed on the porous membrane 31 so as to be in contact with it. In this case, the homogeneous membrane 33 may be in close contact with the porous membrane 31, or may not be in close contact with the porous membrane 31. Because the laminated hollow fiber is constructed in this way, gas is selectively permeated through the homogeneous membrane.
In the example shown in FIG. 3, the permeated gas passes through the micropores 32 and is released toward the bottom of the figure.

The raw material for the laminated hollow fiber produced by the method for producing a laminated hollow fiber according to the present invention may basically be any raw material that can be melt-spun. However, by creating a porous membrane with multiple micropores and a high gas permeation rate,
In order to form a homogeneous membrane with excellent selective permeability, it is preferable to use polypropylene, polyethylene, or a copolymer of polypropylene and polyethylene as raw materials for porous membranes, and to use polyvinylidene fluoride as raw materials for homogeneous membranes. It is preferable to use poly(4-methylpentene-1).

Next, an apparatus for carrying out the method for manufacturing a laminated hollow fiber of the present invention will be described.

The manufacturing method of the present invention can be carried out using the melt extrusion nozzle 5 shown as an example in FIG. Five melt extrusion nozzles have a gas supply pipe 6 in the center, and an inner nozzle part 9 that communicates with the hollow fiber raw material supply lower arranged near the gas supply pipe 6, and further arranged on the outside in the radial direction. It has an outer nozzle portion 1O that communicates with the raw material supply port for the coating layer.

As shown in FIG. 1, a crystalline polymer material for a porous membrane is supplied to a hollow fiber raw material supply lower using a melt extrusion nozzle 5, and a crystalline polymer material for a homogeneous membrane is supplied to a raw material supply port 8 for a coating layer. By supplying a polymer material and performing melt spinning, a laminated hollow fiber having the structure shown in FIG. 2a can be obtained. If the supply of polymeric materials is reversed, a laminated hollow fiber having the structure shown in FIG. 2b can be obtained.

The filaments extruded in a laminated state from the melt extrusion nozzle 5 are optionally formed into a plurality of micropores in the porous membrane and/or into hollow fibers having a predetermined thickness and physical properties. For this purpose, a prescribed stretching process is performed,
It is wound onto a thread cage, etc.

In the melt extrusion nozzle 5, the diameter of the gas supply pipe 6, the diameter and gap size of the inner nozzle section 9 and the outer nozzle section 10, and the extrusion amount of the raw material for the hollow fiber and the raw material for the coating layer, etc. are determined according to the desired lamination type. It can be arbitrarily selected depending on the specifications of the hollow fiber.

Another embodiment of a melt extrusion nozzle for carrying out the manufacturing method of the present invention is shown in FIG. Using the melt extrusion nozzle 40 shown in FIG. 4, a laminated hollow fiber having the structure shown in FIG. 2a can be manufactured. The melt extrusion nozzle 40 of B has a part 42 capable of drawing the extruded porous membrane yarn between the porous membrane polymer material extrusion part 41 and the homogeneous membrane polymer material extrusion part 43. (11). That is, the polymeric material for the porous membrane is melt-extruded by the first nozzle part 41 connected to the gas supply pipe 51, and immediately thereafter cooled to usually 50 to 150°C by the cooling pipe 46 in the first nozzle part. Next, a suitable temperature (20 to 100°C) for stretching is performed using the temperature adjustment tube 47.
The fibers are stretched in a temperature-controlled stretching section 42, and a large number of micropores are formed in the hollow fibers made of the polymeric material for porous membranes in this region. Slits 44°4 on the front and back of the stretching part
5 are provided, and the outer diameter of the hollow fibers is controlled by the slits 44, 45, and the drawing ratio in this area is controlled. The hollow fibers are further cooled sufficiently by the cooling pipe 48 before being coated with the homogeneous membrane polymer material in the second nozzle part 43, whereby a large number of micro cavities formed inside the porous membrane of the hollow fibers. The hole will be fixed. Thereafter, the hollow fibers are coated with a homogeneous membrane-forming polymeric material to form the laminated hollow fibers 1. Note that the melt extrusion nozzle 40 is provided with a cooling pipe and a temperature adjustment pipe, and it is necessary to strictly control the temperature in each part (12), that is, the first nozzle part 41, the stretching part 42, and the second nozzle part 43. Therefore, as shown in FIG. 4, it is preferable to provide a heat insulating layer made of ceramic, for example, between each part.

If a laminated hollow fiber is manufactured using the melt extrusion nozzle shown in Fig. 4, sufficient micropores can be secured in the porous membrane, thereby making it possible to obtain a laminated hollow fiber with a faster gas permeation rate. .

The laminated hollow fibers obtained by the method for manufacturing laminated hollow fibers of the present invention can be applied to oxygen enrichment devices for medical purposes or the interior of automobiles, carbon oxide/carbon dioxide separation devices, dehumidification devices, etc. has been shown to have excellent performance.

<Example> The present invention will be specifically described below with reference to Examples.

Example 1 Polypropylene (melt index 25) was used as a polymer material for a porous membrane, and chili (4-methylpentene-1), which has a higher elongation at break than the polypropylene, was used as a polymer material for a homogeneous membrane. Screw diameter 25W, L/D = 18, compression ratio 3.0) and temperature 2
After melting at a temperature of 100° C., the material was fed to the melt extrusion nozzle shown in FIG. 1 and spun with polyzolopyrene inside. The melt extrusion nozzle used had a three-fold annular slit with an outer diameter of 30 mm and a slit width of 0.5 mm each. Discharge amount 1
011Anan, the yarn spun under the conditions of a draft ratio of 350 was wound up at a winding speed of 25 rV/rQ1n. The outer diameter of the obtained laminated hollow fiber, that is, the outer diameter of poly(4-methylpentene-1), is approximately 300 μm1 Its wall thickness is approximately 2 μm
The outer diameter of the inner polypropylene is approximately 295μm1
Its wall thickness was 25 μm. The thus obtained laminated undrawn hollow fibers are then subjected to a first heat treatment. The heat treatment temperature at this time was 130° C., and the heat treatment was performed for at least 10 seconds in a constant temperature bath in a dry state. Note that a method may be used in which heat is processed in a continuous process in which a dry heat atmosphere is created between two pairs of dry heat rollers and the heat is passed between them.

The laminated hollow fibers subjected to the first heat treatment are stretched by 50 to 300% of the length of the undrawn fibers, resulting in a large number of holes in the inner polyzolopyrene portion (micropores 32 shown in Figure 3).
to form. After stretching, the laminated hollow fibers are again subjected to a second heat treatment at a temperature of 145° C. for 15 minutes in a constant temperature bath. As a result, as shown in FIG. 3, a laminated hollow fiber having a thin homogeneous membrane 33 supported on a porous membrane 31 having a plurality of micropores 32 is obtained.

The performance of the laminated hollow fibers according to the present invention was tested by bundling the laminated hollow fibers to fabricate a membrane module having the structure illustrated in FIG. 5 and having a module volume of 1 mm and an effective membrane area of 2 to 3 m. It was measured. As shown in FIG. 5, the membrane module 52 has an air inlet 53, an air outlet 54, and a permeate gas outlet 55. Since the structure of the membrane module itself is well known, detailed details thereof will be omitted.

When an oxygen enrichment test in the air was conducted using the prototype membrane module by introducing 1017 m1 of air from the air inlet 53, gas with an oxygen concentration of 40q6 was obtained at 2 to 31 times per minute.

(15) Example 2 Polypropylene blowing agent Azodical® was added to 100 parts by weight of polypropylene (melt index 25) as a polymer material for porous membranes. A laminated hollow fiber was spun using the same melt extrusion nozzle as in Example 1 under the same conditions except that a raw material mixed with 5 parts by weight of ADCA was used. The laminated hollow fibers obtained in this way are produced without drawing treatment by generating a large number of pores during melt spinning using a polymeric blowing agent.
It has the structure shown in FIG. 3, in which a homogeneous film made of 4-methylpentene-1 is formed on a porous film made of polypropylene. Using this laminated hollow fiber, a membrane module having the same structure as in Example 1 and having a module volume of 1 mm and an effective membrane area of 2 m was fabricated as a prototype, and an oxygen enrichment test in the air was conducted. . In other words, when air of 101/rrdn is introduced from the air inlet 53, the oxygen concentration is 40'
J gas per minute! I was able to get it.

Example 3 A laminated hollow fiber having the structure shown in FIG. 3 was spun using the melt (16) extrusion nozzle shown in FIG. 4 using the same raw material composition as in Example 1. However, the temperature cooled by the cooling pipe 46 is 80°C, the temperature controlled by the temperature adjustment pipe 47 is 30°C, and the temperature cooled by the cooling pipe 48 is 20°C.
The temperature was set at 0°C. The outer diameter of the laminated hollow fiber thus obtained, that is, the outer diameter of the poly(4-methylpentene-1), is about 257 μm1 Its wall thickness is about 3 μm, and the outer diameter of the inner polypropylene is about 250 μm1 Wall thickness is 30
It was μm. Using these laminated hollow fibers, a membrane module having the same structure as in Example 1 and having a module volume of 11 J and an effective membrane area of 2 m2 was fabricated as a prototype, and an oxygen enrichment test in the air was conducted. That is, air inlet 53 1
When air of 1101 min is introduced, the oxygen concentration is 35Ls.
of gas could be obtained at a rate of 1.51 per minute.

<Effects of the Invention> Since the method for manufacturing a laminated hollow fiber according to the present invention is constructed as described above, it is possible to achieve a high surface gas permeation rate and a sufficient surface gas permeation rate by melt extrusion of two-component polymeric materials at the same spinning station. A laminated hollow fiber with a strength of type hollow fibers can be obtained. In addition, since the method uses spinning at the same spinning station, it has the advantage that the manufacturing process can be easily controlled, and the equipment for carrying out the manufacturing method of the present invention is simple and inexpensive, so it is economical. Laminated hollow fibers can be manufactured.

Further, by using the manufacturing method of the present invention, it is possible to manufacture a laminated hollow fiber having a homogeneous membrane arranged inside and suitable for use under reduced pressure, which was previously impossible to mass produce.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical cross-sectional view of an example 1' of a melt extrusion nozzle used to carry out the method for manufacturing a laminated hollow fiber of the present invention. FIG. 21 and FIG. 2b are longitudinal cross-sectional views of a laminated hollow fiber produced by the manufacturing method of the present invention, in which FIG. 2a is a laminated hollow fiber with a homogeneous membrane formed on the outside, and FIG. 2b is a porous hollow fiber. It is a laminated hollow fiber with a membrane formed on the outside. FIG. 3 is a partially enlarged longitudinal cross-sectional view of the laminated hollow fiber shown in FIG. FIG. 4 is a longitudinal cross-sectional view of another embodiment of the melt extrusion nozzle used to carry out the method for manufacturing a laminated hollow fiber of the present invention. FIG. 5 is a longitudinal sectional view of a membrane module made using laminated hollow fibers. 1... Laminated hollow fiber, 2.31... Porous membrane, 3.
33... Homogeneous membrane, 4... Hollow part, 5.40...
Melt extrusion nozzle, 6.51... gas supply pipe, 7...
・Hollow fiber raw material supply port, 8...Coating layer raw material supply port,
9...Inner nozzle part, 10...Outer nozzle part, 32
...Micro holes, 41...First nozzle part, 42...
Extension part, 43... second nozzle part. Fig. 1 Fig. 3 Fig. 2 Fig. 5 2 JP-A-Sho GO-261510 (7) 151

Claims (1)

[Scope of Claims] 1. A method for producing a laminated hollow fiber comprising a porous membrane and a homogeneous membrane using a two-component thermoplastic crystalline polymer material using a melt-spinning method, the method comprising: spinning the polymeric material of one of the components to produce a hollow fiber, and spinning the polymeric material of the other component to coat the outer periphery of the hollow fiber before winding the hollow fiber. the step of
1. A method for producing a laminated hollow fiber using a melt spinning method, the method comprising the step of forming micropores in a hollow fiber or a coating layer in which a polymeric material for a porous membrane is used. 2. After the two-step spinning process, the yarn in which the two-component polymeric materials are laminated is fully drawn, thereby creating a plurality of micropores in one of the two-component polymeric materials in the yarn. A method for manufacturing a laminated hollow fiber according to claim 1, which comprises forming a laminate hollow fiber. 3. One method is to mix a polymer foaming agent into the polymeric material for porous membranes in an arbitrary ratio, the other is to spin the core polymeric material to produce hollow fibers, and the other method is to make the hollow fibers homogeneous before winding them up. A polymeric material for membranes comprising: a step of spinning so as to cover the outer periphery of the hollow fiber; and forming a plurality of micropores in the hollow fiber with the polymer foaming agent. A method for producing a laminated hollow fiber according to item 1. 4. After the step of spinning the porous membrane polymeric material to produce hollow fibers, drawing the hollow fibers thereby forming a plurality of micropores in the hollow fibers, and then winding the hollow fibers. 2. The method for manufacturing a laminated hollow fiber according to claim 1, wherein the homogeneous membrane polymer material is first spun to cover the outer periphery of the hollow fiber.