JPS63264123A - Composite hollow fiber for removing steam from air or carbon dioxide - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention is particularly useful for dehumidifying air or carbon dioxide gas, but also for dehumidifying water-soluble volatile solvents, such as dimethylformamide or N-methyl, in addition to water vapor. The present invention relates to hollow m-fibers having characteristics that are useful for making air containing higher concentrations of pyrrolidone comply with sanitary standards.

[Problems to be solved by the invention]

In this industry, water vapor contained in carbon dioxide gas is removed,
There is a demand for a composite hollow lI 41m made of oak in order to make the atmosphere in the workplace more hygienic and to provide additional air conditioning (in terms of humidity).

It is therefore an object of the present invention to provide composite hollow fibers which are particularly suited for applications such as those mentioned above.

Another object of the present invention is to provide a composite hollow fiber that can be easily obtained industrially.

Another object of the present invention is to provide a composite hollow fiber that can be used for the above-mentioned purposes even if the pressure difference between the inside and outside of the hollow fiber is small.

Still another object of the present invention is to have a large H20/air or HsO/Cot selectivity coefficient of, for example, about 50 to 1000, that is, a water vapor permeability that is higher than CO2 or air permeability of 50 to 1.
The objective is to provide composite hollow fibers that are 000 times larger.

Another object of the present invention is to provide 200 to 500 Q
4011'/Takumi 3・Hatakeea-cxHg s Preferably 2
20~1000x10-'on"7cm"・-66-m
Large water vapor permeability of Hg (i.e. surface area of composite hollow fiber shaped membrane in 1 second per pressure difference of lllHg)
The composite hollow fiber t is expressed as "the water vapor ii1 as".

Yet another object of the invention is to circulate the wet gas (or gas mixture) to be treated in contact with the internal surface of the t-composite hollow fiber, and to recover the water vapor rich gas on the external surface of the composite hollow fiber. The object of the present invention is to provide a composite hollow fiber that can be used for the above-mentioned purposes.

Another object of the present invention is to provide a composite hollow fiber that enables the above-mentioned use even when carried out at a humidity corresponding to the ambient temperature.Means for solving the problems ] The above objects are achieved by the present invention described below.
In summary, the present invention provides: a) a material having an inner diameter of 130 to 900μ and an outer diameter of 450 to 450μ, which has no selectivity for water vapor contained in air or carbon dioxide;
1500μ polymeric asymmetric hollow fibers having (S) interconnected pore tubes, the largest dimension of the pores being 125μ or less, and at least 80% of the pores having a5-20μ A porous layer having the dimensions of Qυ and in which the volume of the pores occupies 30 to 70% of the volume of the asymmetric hollow fiber, and the pore diameter is α05μ or less and the thickness is 11 to 70%.
b) an asymmetric hollow fiber including a dense layer having a thickness of 1μ;
15-25μ, and further exhibits a much higher permeability to water vapor than to air or carbon dioxide, but substantially less selectivity to oxygen and nitrogen in air. Concerning composite hollow fibers that can be used in particular to remove water vapor from air or carbon dioxide, characterized by a non-intrusive nature, asymmetric hollow fibers (supporting the covering layer) are made from many polymers. Obtainable.

Examples of such polymers include the following:

Fluorinated polymers such as polyvinylidene fluoride, polychlorotrifluoroethylene, copolymers of dichlorodifluoroethylene and chlorotrifluoroethylene.

Polysulfones, such as aromatic polysulfones, polyarylethersulfones as described in 7 Reims Patent No. 1407301, Union Carbide &! 1) 78 items 4sr
UDEx, a polyether sulfone commercially available as UDxh 5sooJ, a sulfonated polysulfone as described in U.S. Pat.
Mixtures of polysulfones and sulfonated polysulfones as described in No. 07182 Polyarylene ethers, e.g. polyarylene polyethers commercially available from Union Carbide under the trade name 1" PKHHJ Cellulose esters, e.g. evadiacetylcellulose, tri-heptyl heptulose and mixtures thereof.

Acrylonitrile-based polymer, acryl El-)
Copolymers and mixtures thereof, such as copolymers of acrylonitrile, methyl methacrylate and sodium methallylsulfonate, copolymers of acrylonitrile and sodium methallylsulfonate, French patent no. Mixtures of anionic and cationic polymers as described in No. 2,144,922.

Polyvinyltriorganosilanes such as those described in US Pat. The asymmetric hollow fibers that support the coating layer are well-known. By the process, in particular, the production of polymer solutions, generally up to 50% by weight, is obtained by extruding this solution through a TIR-shaped spinneret. The solvents used here are dimethylformamide, dimethylsulfoxide, dimethylacetamide, N-
It may be methylpyrrolidone. Hollow fibers are formed by internal or external coagulation by injecting a coagulation liquid into the resulting hollow fibers or by passing the resulting fibers through a coagulation bath. The coagulating liquid may be, for example, water, or water optionally supplemented with a small amount of a polar aprotic solvent, such as dimethylformamide or dimethylsulfoxide.

Asymmetric hollow fibers have an inner diameter of 150-900μ and a diameter of 450μ
These asymmetric hollow fibers contain a porous layer and a microdense layer, the latter dense layer being present on the external or internal surface of the asymmetric hollow fibers. Is the microdense layer 11 to 1 tone thick? :Sound, and has pores with a diameter of a, 05μ or less. The porous layer consists of interconnected pores (honeycomb pores) with a maximum dimension of less than 125 tones, preferably less than 100 μm. These pores do not have a clearly defined geometric shape. , which is why the term pore diameter is not used. The volume of pores (porosity) accounts for 50-70% of the volume of the asymmetric hollow fiber, and at least the SOS of these pores is α5~
It has a dimension of 20μ. Asymmetric hollow fibers have no selectivity to water vapor contained in air or carbon dioxide. This shows that the permeability of the asymmetric hollow fibers is the same for water as for carbon dioxide and air, in other words that the water/air or water separation factor is equal to 1.

The polymeric covering layer provided on top of the dense layer of asymmetric hollow fibers has a thickness of [L15-25μ, preferably aS-15μ.

Polymers that can be used to form the coating layer include, among others:

Polysiloxanes, such as polydimethylsiloxanes or polysiloxanes containing alkyl and aryl groups on the silicon atoms.

Rose Boulin French Patent No. 2414519
A copolymer of dimethylsiloxane and silphenylene as described in No.

Copolymer of dimethylsiloxane and polyurethane O Copolymer of organopolysiloxane and polycarbonate.

Polyvinylpyridine and its copolymers with, for example, styrene.

Polyvinyltriorgafcines and copolymers thereof as described above which can be used to form asymmetric hollow fibers.

As for the coating layer, it must be made clear that its thickness cannot be determined by scanning electron microscopy (by photographs taken); the cross-section of a hollow fiber specimen coated internally or externally with polydimethylsiloxane Inspection after metallization does not clearly distinguish the polydimethylsiloxane layer from the dense layer of asymmetric hollow fibers. Therefore, the inventors decided to place importance on the weight of polydimethylsiloxane attached to the unit surface. This weight can be easily determined by weighing the fibers before and after coating. In the following examples, this value is expressed as the I number of the deposited polydimethylsiloxane per 1 m" of membrane surface area. Since the density of polydimethylsiloxane is approximately 1, the deposited 111/m" is the theoretical thickness of 1 μm. [Examples] Examples illustrating the present invention are shown below.

Example 1 280I polyvinylidene butylene (commercially available from Atochem under the trade name f" FORAPLON 1000HDJ) is dissolved in t-720,51 N-methylpyrrolidone.

This solution was added to the commercially available “
Passed through a diadrose filter WRJ J and spun into hollow fibers while extruding by a gear pump through an annular spinneret of outer diameter aasw with a hollow central protrusion of inner diameter (115-x outer diameter (L250M). A 25% by weight aqueous solution of N-methylpyrrolidone is injected through the central projection of the spinneret, which makes it possible to maintain a perfectly round and regular fiber cross section.

After passing through the air at 23℃ for 15 seconds, the hollow fiber T-30
Immerse into an external coagulation bath containing water at °C.

Next, this fiber was washed with deweired water, stretched 118 times,
It is then dried at 50°C for 24 hours.

The asymmetric hollow fiber thus obtained was (L558
The compact layer on the outside of the 0 fiber with an outer diameter of 1111 and an inner diameter of α195 has a thickness of 155μ, while the porous layer below the compact layer has pores with a maximum dimension of less than 100μ. The majority of these pores, i.e. 90% of them, have dimensions of 1-20μ. The porosity (void volume) of the hollow fibers is 60%.

This asymmetric hollow fiber has no permeability to liquid water at a pressure difference of 2 bar and no selectivity to air or water vapor contained in the next gas.

The asymmetric hollow fibers were then coated with polydimethylsiloxane (registered trademark rRhodo from Rose Boulin).
It is commercially available as rs11 CAF5BJ.

Hereinafter referred to as silicone. ) on the external surface (on top of the compact layer) by immersion in a 10% ffi cyclohexane solution. After crosslinking and curing overnight at ambient temperature, residual solvent is removed by drying at 60° C. for 24 hours. The weight of the silicone deposited in this way is 9777
m'', which corresponds to the theoretical thickness of the target aNj of 9μ.

The obtained composite hollow fiber has a size of 260 x 10 x@/
It had a water vapor transmission rate of cm"·saa-cmHg and a HIO vapor/air selectivity coefficient equal to 70.

This hollow 1 am was cut into 35 lengths of hollow fiber sections, these were assembled into 55 bundles and placed in a tubular external enclosure and filled with epoxy-polyurethane resin! The ends are closed with fat in a known manner. The resulting device (referred to as the permeation device) has two tubes on the outer container that circulate air over the outer surface of the composite hollow fibers, i.e. over the polydimethylsiloxane coating layer, and also has two tubes on the outer container that circulate air over the outer surface of the composite hollow fibers, i.e. over the polydimethylsiloxane coating layer, and It has two tubes communicating with the interior of the hollow fiber.

The obtained permeation device has a diameter of 10% calculated from the outer diameter of the hollow fiber.
It has a membrane surface area of 3-. 21 for nitrogen
It was used to remove water vapor from air containing % oxygen. This operates in the following manner.

Air at 20° C. and 95% humidity is passed into the device by one of the side pipes located on the enclosure and out of the device (by the other tube located on the enclosure). The latter tube is equipped with a valve that creates a pressure difference in the flow circuit.

- Close one of the pipes communicating with both ends of the fiber bundle with a valve, and then use a vacuum pump via the pipe at the other end of the bundle)
The absolute pressure inside the fiber is 15 mbar.

Adjusting the pressure difference in the air flow envelope circulating outside the fibers such that the absolute pressure outside the fibers is 2 bar.

Thus, after being circulated in contact with the outer coating layer of the composite fibers, the air exiting the permeator without traversing the membrane had a flow rate of 90 n/hr and its humidity was 40%. good. The air leaving the permeation device* contained the same oxygen content relative to nitrogen as the air entering the device.

'' L 2 Use the same solution as in Example 1, and add it to the center protrusion with 15
Outside diameter 195 with an inside diameter of ■ and an outside diameter of L187swi
- Spun in a tubular spinneret.

The internal coagulating liquid injected into the fibers is demineralized water.

J1!11st - The bath is a 25 weight≦aqueous solution of N-methylpyrrolidone.

The asymmetric hollow fibers obtained after the same conditioning as in Example 1 contain an inner dense layer and other characteristics are the same as those of the hollow fibers obtained in Example 1 and the porous layer is dense. Atsushi nine on the outside of the hollow fiber.

This fiber has the following dimensions: Outer diameter α980% Inner diameter α612fi Wall thickness [1184M The hollow fiber is cut into 351 sections and placed in a tubular container as a linear bundle of 50 of these tubes.Fiber Tojo Example 1 The container is then closed at both ends with epoxy-polyurethane resin, and both ends of the fiber bundle are opened by cutting.

A polydimethylsiloxane solution is then circulated inside the fiber to obtain an internal wave & L layer. The polydimethylsiloxane solution is manufactured by Rhos-Boulin under the trade name ("Rh
odorgll CAF 5B J is a 10% solution of silicone in cyclohexane.

After crosslinking and curing for 24 hours at ambient temperature, it is dried by passing a stream of air at 50° C. through the interior of the fiber for 24 hours.

The adhesion of the silicone is 911/-, which corresponds to a coating layer with a theoretical pressure of 9.
-・C-equipment Hz water vapor transmission rate and HsO equal to 70
(steam)/air selectivity coefficient.

Air was dehumidified using this device with an exchange surface of 105 m3 calculated from the internal diameter of the composite Il male (with a coating layer on the inside of the fiber). To do this, operate in the following manner.

Air at a temperature of 20° C. and a humidity of 95% is introduced into one of the ends of the fiber bundle. At the other end, a valve allows the pressure applied inside the fiber to be controlled. An absolute pressure of 15 mbar is applied by means of a vacuum pump to the outside of the fiber through a side tube located on the container; the pressure inside the fiber is adjusted to obtain an absolute pressure of 2 bar. The flow rate of air circulating inside (without crossing) the fibers under these conditions was 70 no/hr, and the effluent air had a humidity of 50%. Also, the air leaving the permeator jtt had the same 0 Snow/Ns ratio as the air entering the device.

Example 3 The viscosity at 23°C of an acetyl number of 55% and 12% (W/W) a7tone solution is 297 eras/1.
Polyacetylcellulose (C) is dichloromethane and N
-Prepare a 21% extra weight solution of methylpyrrolidone dissolved in a mixture of 2o,"aO (in g amounts). After passing this solution through a diadrose filter WRJ, it is filtered into its central protrusion. The fibers are spun using an annular spinneret with an outer diameter of 193M, which has an inner diameter of asss and an outer diameter of 1187cm.
90/10 of water and N-methylpyrrolidone (g amount)
Inject the mixture. After passing the 11A fiber through air for 3 seconds, it was introduced into a coagulation bath of demineralized water at 5°C. After exiting the coagulation bath, the fiber was drawn at t-21G in a water bath at 55°C, and then passed over a washing roller. , on this p-ra with fiber at demineralized water 5
Washed for 1 minute, then rolled up], immersed in demineralized water and further 2
Let wash for 4 hours.

After washing, the fibers are dried at 50° C. for 24 hours.

The resulting asymmetric hollow fiber has the following dimensions:

Outer diameter t157 Inner diameter (17M511m! Wall thickness α211 The dense layer on the outside of the seaweed fiber has a thickness of α15μ. Also, the porous layer contains pores whose maximum dimension is 50μ.
The majority of these pores, ie 90%, have a size of 1 to 20 pores. The porosity (void volume) of this asymmetric hollow fiber is 70%.

Then this fiber'k 'Rhodorsfl CAF5
Externally coat the polydimethylsiloxane by dipping in BJ's 5% cyclohexane solution. After cross-linking and curing for 8 hours at 30°C, drying at 60°C for 24 hours. The weight of the applied silicone is 41/m'', which corresponds to a coating layer with a theoretical thickness of 4μ.

The water vapor permeability of this composite hollow fiber is 800X10""1
1/work 3・Ic・1), ■20/air selection coefficient is equal to 1000. oxygen and nitrogen permeability are equivalent),
(L 8 X 10-5x"/lx"#gsc・zH
r IC etc. L a.

A bundle of 30 of these fibers tJ1! Close both ends of the tube with epoxy polyurethane resin in the filter device. The exchange surface obtained is 1035 m'', calculated from the external surface area of the fibers.
There is t'.

using a permeation device as in Example 1 at 20°C.
The water vapor tube was removed from the air with a humidity of 95%. To do this, one of the side pipes of the permeation device introduces the air to be treated which has an oxygen content of 21 - relative to nitrogen.

After being circulated in contact with the covering layer of composite hollow fibers, this air is transferred to a second pipe (on the side of the container) equipped with a valve tube that creates a pressure difference inside the enclosure and thus outside the composite hollow fibers. exit the permeation device by the position). One of the tubes communicating with both ends of the hollow fiber bundle is closed by a valve and the other end of the bundle is connected to a vacuum pump which creates an absolute pressure of 10 bar inside the fibers. The pressure inside the container is adjusted to 2 bar in absolute value. O is thus circulated over the outside of the fiber (without crossing it).
The air flow rate is measured at the outlet of the container. This flow rate is 100
1/hr), and the humidity of the air obtained is 40%. The oxygen content (relative to nitrogen) of this air was the same as the oxygen content of the air introduced into the permeation device. ◎ L-Use the shea heptatylcellulose solution of Example 3 and spin it in the same spinneret. However, the solidification conditions are asymmetric hollow wi
It was modified so that the dense layers of t and m were kept inside the fiber. Therefore, during spinning, demineralized water at 5°C was injected into the inside of the fiber, and then the fiber was exposed to air (L for 3 seconds). After that, water/N-methylpyrrolidone 90710 (heavy f
Ik) Immersion in a 10° C. bath consisting of the mixture. The hollow fibers are then subjected to the same treatment as in Example 3.

After drying, it exhibited the following properties:

Outer diameter: 11!57 m611 Inner diameter: α715 This asymmetric hollow fiber has a dense Mt thickness of 115 μ on its internal surface, as examined by scanning electron microscopy. The porous layer contains pores with a maximum dimension of 50μ, 90% of them having a size of 1-20μ. The porosity of this fiber is 65%.

The asymmetric hollow fibers are then cut into sections of length 55 aa, and 50 of these fibers are placed in a linear bundle within a tubular enclosure (this is referred to as a permeation device).

The fiber bundle is twisted in the previous example and sealed at both ends with epoxy-polyurethane resin in a closed container. The ends of the fiber bundle are opened by cutting a portion of the resin mass after application of the epoxy-polyurethane resin.

Next, a 10% cyclohexane solution of polydimethylsiloxane was circulated inside the m-fiber to obtain an inner coating layer. Polydimethylsiloxane is a silicone resin commercially available under the trade name "Rhodormll CAF 3B J" by Rhos-Boulin. After crosslinking and curing for 24 hours at ambient temperature, an air flow of 50 °C is applied into the fibers.
Dry by circulating for 24 hours. Layered silicone! :Jl is 47/m", which is 6μ
corresponds to the theoretical coating layer of

The composite hollow fiber thus obtained has a density of 500 x 10-
It had a water vapor permeability of 5 csaj/am''·s@a-csHg and a H80/air selectivity coefficient of 560.

The air was dehumidified using the permeator tube described above with an exchange surface area of 0.055 m'' calculated from an internal diameter of mm.

Air with 95% humidity by one end of the fiber bundle i20℃
is introduced into the interior of the fiber. At the other end of the device, a controlled pressure is created inside the ta by means of a valve located in the outlet tube. An absolute pressure of 10 mbar is then applied via a vacuum pump to the outside of the multi-fiber in the fuse located on the enclosure. Also, the pressure inside the fiber is tmm so as to obtain an absolute pressure of 2 bar.

The flow rate of air circulating inside the fibers and exiting the fiber bundle is 10
01/h] and the humidity was 55th. The Ox/N dew ratio of the air leaving the fiber bundle is the Ox/N ratio of the air entering there.
Example 5 The same permeation apparatus as described in Example 4 is used for water t-extraction from carbon dioxide. To do this, a stream of carbon dioxide gas with a humidity of 98% is introduced at 20° C. into the interior of the composite fibers (by one of the ends of the fiber bundle). It is operated as in Example 4 with a pressure of 10 mbar absolute on the outside of the fiber and 2 bar absolute on the inside. After running for 2 #, the flow rate of carbon dioxide gas (COx) at the outlet of the permeation device, i.e., the flow rate of carbon dioxide gas (COx) coming out of the composite hollow fiber at the other end of the fiber bundle, was 801/hr, and the obtained CO The humidity was 315%.

Example 6 A device similar to the permeation device of Example 2 was used to extract water vapor and dimethylformamide (DMF) from air. To do this, DMF vapor is added to the interior of the condensed fibers by one of the ends of the fiber bundle (HE
) 95% air flow (this air is 10 Q W /m'
of DMF e) is introduced at 20°C. Example 4
It is operated as in with an absolute pressure of 10 mbar on the outside of the fiber and 2 bar absolute on the inside of the fiber. After 2 hours of operation, the tILit of the air leaving the permeation device at 20 °C is 1001/hr. The recovered air that circulated inside the composite fiber has a humidity of 30≦ and a humidity of 25 Q.
/m' DMF content. The Ox/N of this partially dehumidified and more hygienic air! 027 of the air to be treated entering the permeation device (from the other end of the composite fiber bundle)
It was the same as the N2 ratio.

Claims (10)

[Claims] (1)a) Not selective to water vapor contained in air or carbon dioxide.Inner diameter is 130-900μ and outer diameter is 4.
50 to 1500 microns, (i) having interconnected pores, the largest dimension of which is 125 microns or less, and at least 80 of the pores;
% has a size of 0.5 to 20μ and the volume of the pores accounts for 30 to 70% of the volume of the asymmetric hollow fiber; and (ii) the pore diameter is 0.05μ or less. and thickness is 0
．． a polymeric asymmetric hollow fiber comprising a dense layer having a thickness of 1 to 1μ; and b) a polymer coating layer having a thickness of 0.15 to 25μ provided on the dense layer of the polymer asymmetric hollow fiber. in particular air or carbon dioxide, characterized in that it exhibits a much higher permeability to water vapor than to air or carbon dioxide, but exhibits virtually no selectivity towards oxygen and nitrogen in air. A composite hollow fiber that can be used to remove water vapor from gases. (2) Composite hollow fiber according to claim 1, characterized in that the coating layer is on the outer surface of the asymmetric hollow fiber. (3) The composite hollow fiber according to claim 1, wherein the coating layer is on the inner surface of the asymmetric hollow fiber. (4) The composite hollow fiber according to claim 1 or 2, characterized in that the coating layer is deposited on the dense layer of the asymmetric hollow fibers by dipping the asymmetric hollow fibers in a polymer solution. fiber. (5) Composite hollow fiber according to claim 3, characterized in that the coating layer is deposited on the dense layer of the hollow fiber by passing a polymer solution into the asymmetric hollow fiber. . (6) Claim 1, characterized in that the asymmetric hollow fibers are formed from a polymer selected from polyvinylidene fluoride, sulfonated polysulfone, polysulfone, a mixture of sulfonated polysulfone and polysulfone, and diacetyl cellulose. The composite hollow fiber according to any one of items 1 to 5. (7) The composite hollow fiber according to any one of claims 1 to 6, wherein the coating layer is formed of polysiloxane or a copolymer containing at least 60% of siloxane units. (8) The composite hollow fiber according to any one of claims 1 to 7, which has a water/air separation coefficient of 50 to 1000. (9) The asymmetric hollow fibers made of polyvinylidene fluoride exhibit no permeability to liquid water at a pressure difference of 2 bar. Composite hollow fiber. (10) Composite hollow fiber according to claim 3 for use in air conditioning.