JPS584810A - Microporous hollow fiber - Google Patents

Abstract

PURPOSE:The titled fibers, prepared by drawing undrawn fibers without holes consisting of a thermoplastic crystalline polymer in the long direction, having micropores formed by the drawing in the hollow fibrous walls and a specific nitrogen permeability, high permeation rate and high strength, and useful for separating gases, etc. CONSTITUTION:A thermoplastic crystalline polymer, e.g. isotactic poplypropylene, is molten and extruded through a spinneret for hollow fibers having a diameter (a) and a slig width (b) by an extruder, to give undrawn hollow fibers having substantially no holes with a pore diameter of 0.01-0.5mu. The resultant fibers are then heat-treated and cold drawn, hot-drawn under heating, and heat- set under tension to give longitudinally oriented microporous hollow fibers having micropores, having an average pore diameter of 0.01-0.5mu, and formed by the drawing on the hollow fibrous walls and a nitrogen permeability at 20 deg.C of 0.01-100cc/cm<2>.min.10cm Hg at the fibrous walls.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hollow fibers useful for purifying and separating gases, liquids, etc., which have micropores in their fiber walls, are oriented in the longitudinal direction, and have high tensile strength. Another object of the present invention is to provide a method for producing high-strength microporous hollow fibers useful as materials for functional materials by bath melt spinning. The present invention also provides a hollow am and a method for producing the same, which are free from the concern of residual solvent such as a solvent for dissolving and removing soluble components.

BACKGROUND OF THE INVENTION Conventionally, planar membranes having fine pores are well known, and various techniques have been proposed for application to purification and separation of liquids, gases, etc., packaging that requires air permeability, and the like. However, when separating and purifying liquids and gases through microporous membranes, using a flat membrane generally requires a large occupied volume compared to the permeate area, making it difficult to reduce the size of the equipment.
Further, in the method of manufacturing microporous hollow fibers by wet spinning, high strength fibers cannot be obtained. On the other hand, the microporous hollow IIA fiber of the present invention has a large surface area compared to its volume, and provides a separation membrane with high efficiency and high strength per unit space. On the other hand, regarding hollow m-fibers, various types of S-fibers have been proposed in the past, including 1-fold and 1-bulk.
Due to its increased covering power and improved thermal effect, it is used as futon cotton for clothing and capotsuta for life preservers. Recently, L-ester hollow fibers have been used for separating water and gases such as helium. However, the fiber walls of these hollow fibers do not have penetrating fine pores, 1 so that the gas or liquid permeation rate inherent in the polymer is not changed in any way.

The microporous hollow fibers of the present invention are oriented in the length direction and have micropores that penetrate through the fiber walls, so they have a much higher permeation rate than the gas or liquid permeation rate that the polymer originally has. In addition, microporous fibers made of polyamide, polyester, and polyoxymethane are known to have high strength (υ8PII61111Dxυ5ps5a1sas).
These Ili fiber forms are not hollow fibers and do not have transient properties like the fibers of the present invention.

In view of the above, the present inventors have arrived at the present invention as a result of many years of seed blue research. That is, the present invention comprises a thermoplastic crystalline polymer having substantially 0.01 to 0.0. 1 obtained by stretching in the length direction an undrawn yarn without IH through-holes
It is a hollow fiber oriented in the length direction, and the hollow fiber wall has penetrating micropores with a pore size (average) of 0.01 to 0.0, a μ caused by stretching, and the nitrogen content in the 111i fiber wall is
The amount of transmission at od is 0.01 to 100 (C/-・1・io
Regarding oriented microporous hollow sIm with the value of amlig.

The present invention will be explained in more detail. Examples of the thermoplastic crystalline polymer used in the present invention include polyolefins such as &lJ ethylene 1 polypropylene 1 ethylene/Puda pyrene copolymer, polyamide 11 polyethylene terefin such as nylene 61 nylene 66S nylin 12, etc. 7 talates＼
1-diester 1-polyvinylidene fluoride such as polyethylene terephthalate/isophthalate, polybutylene terephthalate 1-polyethylene-1,6-7-talate, fluorine-based polymers such as 1-polyvinylidene fluoride/tetrafluoroethylene copolymer, Polyoxymethylene, etc. can be added to these polymers, if necessary, stabilizers, one UV absorber, one slenderizer, one dye, and one pigment, one crystal nucleating agent. Furthermore, the above-mentioned crystalline polymers may be blended with each other, and these crystalline polymers may be combined with ELAST! If you add inorganic substances such as - or non-grade polymers such as rubber) and calcium carbonate, it will be a stone's throw.

The microporous hollow filament of the present invention is produced [L method is to obtain hollow fibers by S-melt spinning a stone-crystalline polygonite body having a fine-forming property through a spinneret. The discharge opening diameter (outer diameter) of the annular slit of the spinneret is Q, l-19 m.

The width of the annular slit was 0.01-I m, the spinning temperature was 15-tsot- higher than the melting point of the electrolyte, the winding speed was 10 mm/- or more, and the draft ratio was 100-10 mm.
Melt-spun in the range of 00, the outer diameter is 3- or less, and the wall thickness is 10
Create hollow fibers of 0μ or less, and
Heat treatment is carried out at a low temperature of 10-10Qt', and then one-stage stretching is performed to achieve an elongation of 5 ounces or less by multi-stage stretching, resulting in nine penetrating pores with a pore diameter (average) of 0, Sμ or less in the fiber wall. This is a method for manufacturing hollow fibers.

In melt-spinning of these crystalline polymers.

Ordinary melt-spinning equipment with screw or gear pumps and hollow fiber applications is sufficient - the polymer melted in the screw extruder or melt grate is conveyed by a gear pump to a hollow fiber spinning nozzle and then through an annular slit. The yarn is spun into the spinning tube, cooled and solidified with cold air, and transferred to the II machine. taken.

An example of the hollow m* spinneret of the present invention is shown in FIGS. 1 and 3. The pqm-shaped slit of the hollow fiber spinning die has a discharge opening diameter
The outer diameter of flQ coral) A is 0, 1-10-, the width of the slit) is 0. The range of OI to 5 snow is *tL0. Even if the discharge opening of the annular slit is narrowed, it will become thicker, and if the draft ratio is increased in this spinning method, there will be many yarn breakages. This makes spinning difficult. In addition, if the slit is too narrow, the shear rate of the fluid dalimer becomes too high, which tends to cause melt 7 lacquer, making it difficult to obtain uniform fibers, and increasing the number of yarn breakages. Medium 9 obtained when the slit is too wide
! - Thickness of the fiber; thickens this hollow wutiaoea
In order to reshape the micropores penetrating the fiber wall, the hollow wire # is stretched, and if the main wall thickness is thick, it will penetrate and the micropores will be less likely to occur. It is advantageous to obtain a microhole f through which IIs# is formed, so the dimensions of the K thread cap are preferably the same as above. The shape of the annular slit of a fiber spinneret is not a book that focuses on closed rings, but rather C-shapes (circles with a partially cut-out rim), star-shapes, triangles, squares, polygons, and these shapes. There is no problem with any shaped object, such as a book, as long as it is made by spinning hollow fibers. This S apricot has a discharge port diameter of I! l! The length of the enclosure is converted into a circle, and the diameter is calculated from the book. Furthermore, inside the hollow fiber group? It is preferable that the slit of the tying cap is a continuous circle for manufacturing the microporous hollow 1# hollow spinning yarn equipped with a gas supply pipe l for supplying gas to the part. The gas can be supplied or inhaled into the hollow part of the fiber by using a ring-shaped object, either by natural inhalation by stuttering or by controlled inhalation by regular inhalation.However, depending on the amount of gas supplied to this hollow part, the hollow fiber The outer diameter and wall thickness will be affected.If the amount of gas supplied is large, the fibers will become lantern-shaped!II is not preferable.

It is preferable that the outer diameter of the obtained 1lIIIi be smaller than the discharge opening diameter of the tying nozzle.If the amount of gas supplied is too small, the fiber will not be a hollow IIa fiber.

In the case of No. 4 with discontinuous slits (method in which outside air is sucked in through cuts in the discharged polymer) such as the C-engraved thread cap (see Figure 1), gas is naturally sucked into the hollow part. The polymer discharged from the spinneret has a draft ratio of 100-1000.
It can be wound within the range of . Draft ratio is the ratio between the winding speed and the linear speed at which the polymer is discharged from the spinneret, and is expressed by the following formula.

If the draft ratio is low, even if the wound hollow fiber is drawn, no micropores will be generated.If the draft ratio is high, the tension applied to the yarn during spinning will exceed the melting point strength of the polymer. Thread breakage occurs at t. y rat ratio is 100-
A value of 1000 is preferably sOO~■]O, medium? When gas is forcibly inhaled into the hollow part of the fiber during spinning, the preferable draft ratio for obtaining a hollow fiber becomes smaller than when it is naturally inhaled. It depends on the amount of gas inhaled, but in the case of forced income, the draft ratio is II to $0.
0゜ own aqL person field 41) h draft ratio is 400~II
I like O@.

Inside obtained in this way? - The thin material preferably has an outer diameter of 1 m or less and a wall thickness of 100 μm or less.

If the thickness of the fiber is too thick, it will be difficult to maintain its shape, and it will easily collapse and flatten when external pressure is applied. *When passing gas or liquid through the hollow part of the fiber, there is a tendency for the pressure loss to increase. The outer diameter of the hollow fibers is preferably 10 to 00μ. Hollow #a #1
When the thickness is 0, it is easy to obtain penetrating micropores when #1 is stretched, which is relatively thin, and the preferred thickness is S~60μ. The outer diameter and wall thickness of the hollow fiber can be observed using an optical micrometer or a scanning electronic spot mirror and measured at a rate of 1kK.

The winding connection of the hollow fiber is preferably 10-/- or more in order to quickly achieve the above draft ratio.
s/m is preferred. If 41 # is taken at a high speed, the orientation of the molecular chains of the polymer will be improved, and micropores will be generated in the subsequent drawing process. The linear speed at which the polymer is discharged from the spinneret is extremely slow, and the solid point of the yarn approaches the spinneret, making spinning unstable. Molecular orientation of polymer 4b
Stretching the 2-h roll of a low-quality book reduces the occurrence of curling.

In order to obtain a more uniform m-, it is effective to blow an air stream onto the molten polymer thread discharged from the tying nozzle.

The spinning temperature is the melting point of the polymer #11! A temperature range of 1-150°C is preferred. If a good @# is obtained, result is A.
The M degree is preferably as low as possible, in the case of IIs polypropylene, it is 10-800t, preferably file-neo, and in the case of high-density polyethylene, it is 180-5set', preferably 100-MaOt. ″
, f. In the case of polyvinylidene fluoride, 10~5oo
t', preferably 5so-ssot, is obtained by spinning at a relatively low #ll and high F raft ratio.The molecular orientation of the hollow fiber is considerably higher than that of an unoriented fiber. Molecule 4 Mukami no Finger I/Il,! −
[7 and express it using the birefringence II x l O-”
A value of 10 or more is good, for example, a polypropylene hollow fiber.
xl (preferably a value of 1" or more; this value can be determined by a conventional method using a polarizing microscope.

The crystallinity of the spun and wound hollow fibers is relatively high, but if this is still not sufficient, the fibers are strained in a lagoon range 10~foot' below the melting point of the polymer. If the relaxation heat is controlled to a certain degree, a high degree of crystallinity can be achieved. Based on the density determined from the crystallinity AJTM-DIISOI,
The crystal density can be determined from the value of the amorphous book [Kenzo Okamura et al., Introduction to Polymer Chemistry IP86 Kagaku Kaijin (1117g)]. It is fine, but SO whisper or above is more suitable. When the as-spun hollow fibers reach 1 lPc, the degree of crystallinity can be increased by leaving them for a while or by heat-treating them. For heat treatment, heat treatment #l! The actual value is 110-18 for polypropylene.
For 0'C1 high-density polyethylene, it is 90~tset, and for polyvinylidene fluoride, it is 100-14et''.The heat treatment time is 10 seconds or more, preferably between 10 seconds and 1#!
'igl is recommended. If the degree of crystallinity increases when the device is heated at room temperature, it is fine.

No pores are formed in the hollow S* in this state.

This hollow fiber exhibits remarkable elasticity.

When the hollow fiber is drawn, 8 micropores are formed.The generation of micropores is caused by the elongation percentage exceeding the yield point. and stretching g
As I# increases, the porosity increases markedly.
average value) is less than O,aμ, and most of the pore diameters are O,os
-o, sp. In other words, the fibers with or without stretching are ordinary hollow fibers. Stretching starts with microporous hollow fibers, and #-1 stretching is indispensable under manufacturing conditions in order to obtain microporous hollow fibers. temperature set'
If the stretching below is cold stretching, and the stretching above 801 is hot stretching, one-stage cold stretching will result in an elongation of 10% compared to the initial length.
It is possible to stretch the fiber to 0%, and the fiber can be stretched to 0%, and it can be stretched in multiple stages using a combination of cold stretching and hot stretching.
It is necessary to carry out cold stretching until micropores are uniformly generated during stretching. If hot stretching is performed first, the generation of micropores will be significantly less even after stretching, and no micropores will occur. B% or more, preferably File～・・−
If stretching is followed by hot stretching, the stretching ratio will increase compared to cold stretching, and more micropores will be generated.For example, in polypropylene, 801: or less, preferably 1-
A one-stage cold stretch of 60 to 160% is carried out at a low temperature from 1 room temperature to 1000 cm or less. In the case of one-stage stretching, first h-Zoos, preferably #-
Cold stretching to tIO~609 followed by 110~I
80 to 4141 strokes of hot stretching at IIt, good luck.
-It is better to stretch the paper in three stages.
Multi-stage stretching of one or more stages may be used.

The total amount of stretching is preferably 100 degrees or less. High-density polyethylene is cold-stretched at SO~110% at a low temperature of 80 tons or less, preferably from room temperature to 160 tons.In the case of one-stage stretching, first to-s at the above-mentioned low temperature.
os cold stretching, followed by 5G-stretching at 9O-11Or
It is preferable to heat-roll 1110 and stretch to a total of 4e-1100. Furthermore, polyvinylidene fluoride Kk is preferably 8
First, the rumored 1st stage cold stretching is carried out at a low temperature of 0 to 60%, preferably from 0 to 601: In the case of S stage stretching, first cold stretch 10-80% at the above-mentioned low temperature, and then Then 90-1401: SO-■] attack, total 80-100
It is preferable to carry out long-distance drawing, and cold drawing can be carried out at a low temperature of -601: or less, but it is too large to be used industrially. The stretching can be carried out at a stretching speed of 1 to 1 o'%/-.

Furthermore, by immersing the material in an organic 71 rule and drawing it during stretching, it is possible to increase the porosity and enlarge the pore diameter.

After one stretching in the hollow part II of any polymer, it is stretched at a temperature 10 to 100"C lower than the bending point of the polymer.
! Dimensional stability can be improved by heat setting in a relaxed state of 35°C for the total amount of stretching per 1 stroke. Dekel (1#
It is effective to fix it at a temperature of 1IOt'. It is preferable to open for 8 seconds or more during heat setting. 1. The microporous hollow fibers of the present invention can be obtained by the method described above, but the method is not limited thereto.

The microporous hollow II of the present invention is oriented in the length direction K11P, and its orientation usually exhibits a birefringence value of foxlo-'' or more.
os-o, sμ, and micropores. It can be measured using a mercury porosimeter with fine pores. Outer diameter of microporous hollow fiber #''t9wt9w or less 10
Less than 0μ, the porosity of the fiber ** part is normal! 10-a.

At 1 o'clock, the SO arc was reached and the amount of nitrogen gas permeated at SOυ was 0.01 N100 (Z,, /c4mmmm 1105H
It shows the elongation.

The use of water for pollution prevention, water purification, recycling, etc., is one of the reasons why time is so busy. In addition, many substances are absorbed into the chewing fibers and/or hollow parts using the uninvented micropores of the fibers! For example, microporous hollow WA fibers made of polyolefin are suitable as oil catchers for oil spread on the water surface. Furthermore, it is also possible to actively incorporate various substances into the hollow parts of the fibers and/or the micropores of the fibers.
) Built-in stone material containing IET and used for water purification and metal collection. I can do it. By filling the hollow part with insecticides and fragrances and letting them volatilize through the micropores, a phantom Kasuri-like effect can be obtained. Furthermore, it can be used by filling it with carp suckers, sucking agents, liquid crystals, fertilizers, medicines, etc. The above-mentioned substances can be incorporated or filled in by impregnating microporous hollow fibers with a liquid containing these substances, but it can also be used in impregnated fibers and after TR-impregnated treatment. By heating the microporous hollow fiber of the present invention, which can be used after 4 tsubo of encapsulation by heat treatment, for example, polyprobean can be heated to over 160 t', high-density polyethylene to over 110 t', and polyvinylidene fluoride to about 14 t' (Since the micropores disappear at temperatures above 1°C, various substances can be sealed inside the micropores and the hollow space.

The measurement method used in the present invention is shown below.

(1) Density! AS'l'M-DI! 103K at a temperature of 17r.

(Melt index: ^STM-D11811
fi80t" for polypropylene than K, L18Kl
Measured with polyethylene at 1000°C and 818KI.

(3) Dimensions of hollow fibers: The cross-section of the hollow fibers was determined by observing the cross section of the hollow fibers using a biological microscope mold manufactured by Nippon Kogaku Kogyo at a magnification of 50 to SO.

(4) Porosity and pore diameter 8 Measured using a Mercury Borosinotor Model 800 manufactured by Carlo Elpa.

(6) If the weekly amount of permeation: perforation hollow turret fiber 100 wood 0
Bundle the letters together and harden the cut end of the fibers with epoxy St resin.
A part of the fiber was cut to align the fiber end faces, and an internal pressure of 10 ell- was applied to the interior of the hollow fiber to determine the unit amount of nitrogen permeating to the outside through 1 PWI of the hollow fiber. Refractive index: 9, measured using an Al11-point micrometer PO9 manufactured by Niolinbus Optical Industry Co., Ltd.

(7) Strength and elongation: using a shoplifting tester Tensilon II T M-II type manufactured by Choyobuchi Co., Ltd., yarn length 40W, test Ml actual! Measured in lO fins/min, the 11 constant value is for the real cross-sectional area excluding the hollow S.

Example l.

Isotactic polypropylene C (melt index 1.0) is extruded using an extrusion rod (screw diameter * Ow %L /
D l 11 , compression ratio 8.1)
! The material was melted at 1 int, and spun using a circular slit equipped with a gas supply pipe, 9 hollow spout C discharge ports, and a slit width law.

Discharge amount m v t/m, discharge 411 speed 0.18*
/am, a winding speed of tOws/m, and a draft ratio of 4o. Gas is supplied into the hollow fiber by natural suction. Obtained and reported? The dimensions of 1IJlli are outer diameter 41 (
lμ, wall thickness 11p. Density (1,1111f/
al, crystallized carbon #f48 with a birefringence index of 16 0
Running in an arc, birefringence F! 14XlO"-"K increased. The degree of crystallinity was determined by calculating the crystal density of 0.188 #/W and the distance between the amorphous zones by 0.810 F/aa. And this heat @-
The processed hollow fiber was once cold-stretched at 10 tons for 10 times, then 1
It was hot-stretched from 0 to 5 o'clock in 4i shift. Total stretching amount go~
■] - I am sorry. Heat set this in 1ull state at 14@t for 1 minute and get a medium? The fibers had micropores that disturbed the light and gave it a white color. This chew readily absorbed ethyl alcohol. When the amount of nitrogen permeation through this hollow fiber was measured, it showed a significantly large value, and it was clear that there were micropores that penetrated through the fiber.

In addition, the results of measuring this microporous hollow fiber with a mercury zerosimeter revealed that most of the pores had a pore diameter of 0, es to 0,1 μ. Table 1 shows changes in microporosity depending on east stretching and amount of stretching.

It was rumored that the breaking strength of the Yagurabaji of 1-8 above in Table 1 was 14 to 4/s$, and the breaking elongation was 8 seconds.

Comparative Example 1) Example 1. After heat treatment of the hollow fibers spun, the amount of hydrogen permeation and the porosity were measured without stretching, and both were zero. @
tl<show results.

Example When polymerizing East Isotactic propylene (melt index number), 10% of Quinacrylic
Using an extruder (screw diameter 8O-1L/DI easy, compression ratio ti), 18
A hollow spinneret with a gas supply pipe (
Outlet l! 11. Spinning from an annular slit with an outer diameter of 0.811 t and a slit width of 0.1 mm of the gas supply pipe.

Discharge amount Fillf/m, discharge linear velocity o, go-7'-1
Draft ratio j01 in the range of winding speed 40-go6m/-
)-1009 and wind it up. Gas is supplied to the hollow @ direction by forced suction, and this hollow fiber is heated to a temperature of 11:
100% stretching at 14+ 9mg°C, heat set at 14Jlt for 1 minute under tension.9. F
As the raft ratio increases, the occurrence of micropores increases, and the porosity is larger with the addition of nitrous nucleation energizer V compared to the one without addition. The porosity was determined using a mercury porosimeter. The results are shown in @S table.

Comparative Example 2 *Under the same spinning conditions as Example Yuki, only II Toriyaka 14)
II was taken due to the F raft ratio of 10 in the range of m/s. This hollow fiber was used in Example 1. The porosity of the resulting book was measured and found to be zero. The results are shown in Table 1.

Table 3 Example 1 High density polyethylene (melt index 0.11.@
J0.911) using an extruder (screw diameter 1 (1 m, L)
/D Katsuboku 1 compression ratio 11.1) and gear pump 411s!
Then, it was expanded at a temperature of 5 sor and spun using a hollow yarn feeder (C-shaped slit with a discharge port of 8-1, a width of the slit part of O0-1, a width of the discontinuous slit part of O, and a C-shaped slit of 8 W). Spring was taken with a discharge amount of 11417wm and a discharge linear velocity of 0-/-1 spring removal speed of 1m00 town-1F raft ratio @OO. The dimensions of the obtained hollow fiber were outside @aSμ and wall thickness 11μ. Hollow fibers with a multi-phase refractive index of 1lxlO''
110t'' for 1 minute, then SO width cold stretching at 25℃.Subsequently, the first stage stretching temperature was varied from room temperature to 110t'' for 60% stretching.The total amount of stretching was F!80. This was heat-set at 110℃ for 1 minute.The resulting fibers easily absorbed ethyl alcohol and it was found that there were open pores.Measurement using a water porosimeter revealed that most of the pores had a small diameter. It was found that it was distributed in !wl of o, om to 0.1μ.

The conclusion is shown in Part 8.

Comparative Example 8 Hollow fibers spun and heated under the same conditions as in Example 8 were cold-stretched to a width of 80 mm using SSt, and then the S-th stage stretching temperature was lowered to l.
I made sure to stretch the ios with ll-111t, #fJ stretching device @O
I came to the island because of the sound. In this case, after the stretching is completed, the same l as the stretching S
Heat and harden for 1 minute at a temperature of 1 liter. It was found that the resulting hollow fibers were transparent, did not absorb ethyl alcohol, and had no pores. Results first! Show IK.

Table 3 Example: Polyvinylidene fluoride (Tero) was added to the extruder 1 and hollow spinning chamber C discharge tube diameter 1 mm.

Outer diameter of gas supply pipe o, y s*, inner diameter o, s s
The yarn was fed with @WIsset from the annular slit at >. Discharge linear velocity O, Te Om/wa1 take-up f l 10
m1wm, )' Rat specific gravity OO was defeated. Junior high school 91
．． Gas is supplied into the body through forced inhalation. The dimensions of the obtained hollow fibers were 181μ in outer diameter and 40μ in thickness. After processing this stiffness at 110t' for 1 minute, it was stretched for 111 minutes at a temperature of -1Ot', followed by curvature at 110t'.
It was extended by 811, and the #P key extension was 0%. Fix it under tension for 80 seconds at @1 dew b°C. The obtained hollow fibers absorbed ethyl alcohol by volume s[mu], and the pore diameters measured with a mercury porosimeter were mostly o, os-o, and t[mu]. The porosity was 8%.

[Brief explanation of the drawing]

FIG. 1, the first row, shows an example of the shape of the discharge opening of the second tying nozzle for spinning the fibers of the present invention. Patent applicant: Toyo Keisatsu Co., Ltd. Figure 1 Figure 2 r11

Claims (1)

[Claims] (1) Substantially 0o0 consisting of a thermoplastic crystalline polymer
It is a hollow fiber oriented in the length direction obtained by stretching in the length direction an undrawn yarn that does not have through holes of 1 to 0.8μ. ) has penetrating micropores of 0.01~0.S, and the amount of nitrogen permeation through the fiber wall at SO°C is 0.01. o1～z o
Oriented microporous hollow fibers with a value of o cc/-k.