JP5155599B2 - Method for producing hollow fiber membrane module for deaeration - Google Patents

Description

  The present invention relates to a degassing hollow fiber membrane module having resistance to organic solvents used in fields such as the electronics industry, food industry, and beverage industry.

  Separation membrane modules such as reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes, gas separation membranes, and dialysis membranes are used in processes such as pervaporation, solvent filtration, solvent treatment, and chemical degassing. . In such applications, solvent resistance is required not only for the separation membrane itself but also for other members constituting the module.

  For example, when a hollow fiber membrane module having a potting portion made of a thermosetting resin is used for the above-mentioned applications, the thermosetting resin swells and elutes depending on the type of the solvent or chemical solution, and cracks are generated. Problems such as a decrease in adhesiveness, occurrence of leakage, and a decrease in the purity of the processed product may occur.

  Therefore, Patent Document 1 and Patent Document 2 propose a method of forming a potting portion by molding a thermoplastic resin instead of a thermosetting resin, thereby improving the solvent resistance. Specifically, an example is shown in which a potting portion is formed at the binding end of the hollow fiber membrane using the same material as the hollow fiber membrane or a compatible thermoplastic resin.

  However, in this method, the binding ends of the hollow fiber membrane during the molding process of the potting part are completely melted, and the hollow fiber membrane loses thermal deterioration or porosity and loses flexibility. Therefore, the liquid-tight integrity between the hollow fiber membrane and the potting portion is enhanced, but on the other hand, the hollow fiber membrane at the base portion buried in the potting portion becomes fragile and easily cracks due to chemical or physical invasion.

Patent Document 3 also proposes a method of forming a potting portion by molding a thermoplastic resin instead of a thermosetting resin, thereby improving the solvent resistance. Specifically, in the embodiment, the potting portion is formed using polyethylene with respect to the polypropylene hollow fiber membrane. However, the adhesion between polyethylene and polypropylene is low, and only the anchor effect due to the penetration of potting resin into the hollow fiber membrane pores can cause defects in the adhesive interface due to the switching of organic solvents accompanying line cleaning, etc. Distortion due to thermal shrinkage differences may remain. Furthermore, when the module is subjected to chemical or physical invasion, the potting part itself or the hollow fiber membrane tends to crack.
JP-A-1-164406 Japanese Patent Laid-Open No. 1-281104 Japanese Patent No. 3174267

  The present invention has been made to solve the problems of the prior art. That is, an object of the present invention is to provide a method for producing a hollow fiber membrane module in which the hollow fiber membrane and the potting part are bonded and fixed in a highly liquid-tight or air-tight manner without impairing the properties of the hollow fiber membrane.

  The present invention binds a plurality of degassing hollow fiber membranes having a porous support layer and a non-porous homogeneous layer, and melts a polymer that is a potting resin at the binding end of the hollow fiber membrane. In the method for producing a degassing hollow fiber membrane module that forms a potting portion for liquid-tight potting of the inside and outside of the hollow fiber membrane in the module case after cooling and forming the homogeneous layer The polymer that is the potting resin is melted by heating at a temperature that is not less than the Vicat softening point of the polymer, not less than the melting point of the polymer that is the potting resin, and less than the melting point of the polymer that constitutes the support layer. A method for producing a hollow fiber membrane module for deaeration, characterized in that a polymer constituting a layer and a polymer that is the potting resin are fused.

  In the present invention, since the potting resin and the homogeneous layer are fused within a specific temperature range, the hollow fiber membrane and the potting portion can be bonded and fixed satisfactorily. Moreover, since the support layer portion at the binding end of the hollow fiber membrane does not melt during the molding of the potting portion, it can be bonded and fixed satisfactorily while maintaining the porosity, flexibility and other characteristics, and can be bonded by the anchor effect. It can also be fixed. Therefore, sufficient tolerance can be shown also to chemical or physical invasion.

  The degassing hollow fiber membrane used in the present invention is a composite membrane having a support layer that is a porous body and a homogeneous layer that is a non-porous body. This composite membrane may be, for example, a two-layer composite membrane of a homogeneous layer and a support layer, or a three-layer composite membrane in which the homogeneous layer is sandwiched between support layers.

  The homogeneous layer of the degassing hollow fiber membrane is a layer having a gas permeability even though it is a non-porous body. The polymer constituting the homogeneous layer is not particularly limited. Various polymers known to be usable as a gas permeable homogeneous layer of a degassing hollow fiber membrane can be used.

  The polymer constituting the homogeneous layer is preferably a polyolefin resin. The polyolefin resin is a polymer obtained mainly from olefin. It may be a polymer obtained by using only olefin, a copolymer of olefin and another monomer, or a modified resin thereof. Specific examples include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), linear very low density polyethylene (VLDPE), polypropylene, ethylene / α-olefin copolymer. Polymer, poly-4-methylpentene-1 (PMP), ionomer resin, ethylene / vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer (EMAA), ethylene / acrylic acid Methyl copolymers, ethylene / methyl methacrylate copolymers, modified polyolefins (for example, homopolymers or copolymers of olefins and unsaturated carboxylic acids such as maleic acid and fumaric acid, acid anhydrides, esters or metal salts) Etc.) and the like.

  The polymer constituting the homogeneous layer is preferably made of a polyolefin resin having a ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) of 3 or less. When Mw / Mn is 3 or less, strength is improved while maintaining moldability, and mechanical defects (craze) are reduced. Moreover, since this polyolefin resin has few low molecular weight components, the molding temperature of the module part can be lowered and elution can be reduced. As a result, the properties such as moldability, mechanical strength, solvent resistance, and low elution required for the potting resin are satisfactorily satisfied without impairing the properties of the hollow fiber membrane.

  The polymer constituting the homogeneous layer is preferably a polyolefin resin obtained using a metallocene catalyst. When using a metallocene catalyst, the molecular weight distribution is basically narrow compared to the case of using other catalysts (such as Ziegler-Natta catalyst), although it is the same type of polyolefin resin, low molecular weight components and A polyolefin resin having a low crystalline component and a low melting point can be obtained.

  In particular, among the metallocene catalyst-based polyolefin resins, ethylene / α-olefin copolymers are effective as gas permeable members. Typical examples include ethylene / α-olefin copolymers and ethylene-propylene obtained by using an insight (single site) catalyst developed by Dow Chemical Company, a constrained geometric catalyst which is a kind of so-called metallocene catalyst. A copolymer is mentioned.

  The ethylene / α-olefin copolymer is preferably an ethylene / C3-C20 α-olefin copolymer. The ethylene / C3-C20 α-olefin copolymer is a copolymer of ethylene and at least one type of α-olefin having 3 to 20 carbon atoms. Specific examples of the C3-C20 α-olefin include propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-octene. Furthermore, a C4 to C20 α-olefin is preferable, a C6 to C8 α-olefin is more preferable, and 1-hexene or 1-octene is particularly preferable. As the ethylene / α-olefin copolymer, a copolymer obtained by copolymerization using a C3 to C20 α-olefin at a ratio of about 10 mol% or more (particularly preferably about 20 to about 40 mol%) is preferable.

  Examples of commercially available ethylene / C8α-olefin copolymers include AFFINITY (trademark) manufactured by Dow Chemical Company. Examples of commercially available ethylene / C6α-olefin copolymers include Evolue (trademark) manufactured by Prime Polymer Co., Ltd.

  Examples of the ethylene-propylene copolymer include VERSIFY (trademark) manufactured by Dow Chemical Company.

The polymer constituting the homogeneous layer, density (measured by JISK-7112 = ASTM D1505) is 0.940 g / cm ³ or less, 0.85 g / cm ³ or more polyolefin resin (particularly polyethylene and ethylene · alpha-olefin copolymer Polymer, ethylene-propylene copolymer and the like). More preferably 0.920 g / cm ³ or less on the upper limit value of the density, and more preferably 0.86 g / cm ³ or more for the lower limit. Each of these upper limit values is significant in terms of further improving the permeability of gas (oxygen or the like) in the homogeneous layer, and each of the lower limit values is significant in terms of a practically suitable melting point or softening point.

  In the polymer constituting the homogeneous layer, additives such as an antioxidant, an ultraviolet absorber, a lubricant, an antiblocking agent, a colorant, a flame retardant, and the like are added to the polymer as long as it does not impair the purpose of the present invention. Can be added.

  The support layer of the degassing hollow fiber membrane is made of a porous material, that is, a porous membrane, and fulfills the function of supporting the homogeneous layer. The polymer constituting the support layer may be any polymer having a melting point higher than that of the polymer constituting the homogeneous layer, and various polymers known to be usable as a porous support layer for a degassing hollow fiber membrane. Can be used. The polymer is preferably a polyolefin resin. In particular, a high-density polymer is preferable from the viewpoint of pore opening. Specific examples include high density polyethylene (HDPE) and polypropylene.

  The porosity and pore size of the support layer are not particularly limited. Usually, the porosity is preferably 30 to 80 vol%. When the porosity is 30 vol% or more, gas permeability is improved, and when it is 80 vol% or less, mechanical strength such as pressure resistance is improved.

  Further, the melt flow rate (MFR) of the polymer constituting the support layer and the polymer constituting the homogeneous layer is preferably from 0.1 to 10 g / 10 min, more preferably from 0.3 to 2.0 g / 10 min. The upper limit of each range of MFR is sufficient to prevent the fluidity of the polymer and the thickness of the homogeneous layer from flowing out of the resin for the homogeneous layer to the support layer, and the gas permeation performance as a degassing membrane. This is significant in terms of maintaining and suppressing softening damage during molding of the potting part. The lower limit is significant in terms of extrusion moldability. MFR is a value measured at a test temperature of 190 ° C. and a test load of 2.16 kgf in accordance with JIS K7210.

  In the hollow fiber membrane for deaeration, the thickness of the homogeneous layer is preferably 0.5 to 10 μm. When this thickness is 0.5 μm or more, pressure resistance during use is improved, and when it is 10 μm or less, gas permeability is improved. Further, the thickness of one layer of the support layer in the case of the two-layer composite membrane, and the thickness of one layer of the support layer on the inner layer side and the outer layer side of the three-layer composite membrane are preferably 10 to 200 μm. If the thickness is 10 μm or more, the mechanical strength is improved, and if it is 200 μm or less, the outer diameter of the hollow fiber membrane is reduced, and the volumetric efficiency of the membrane when incorporated in the membrane module is improved.

  The thickness of the hollow fiber membrane is not particularly limited. Usually, the outer diameter is preferably about 100 to 2000 μm. When the outer diameter is 100 μm or more, the gap between the hollow fiber membranes is relatively wide and the potting resin is likely to enter. If it is 2000 μm or less, the overall size of the module having a large number of hollow fiber membranes is reduced, and accordingly the volume of the potting part is reduced. As a result, the dimensional accuracy is reduced due to shrinkage during molding of the potting part. Can be suppressed.

  The composite hollow fiber membrane is manufactured through, for example, a multilayer composite spinning process and a stretched porous process. The specific example of the manufacturing method is as follows. First, a molten polymer (high-density polyolefin, etc.) for the support layer precursor (unstretched layer) is supplied to the outermost layer nozzle part and innermost layer nozzle part of the concentric composite nozzle nozzle, and the homogeneous layer is melted to the intermediate layer nozzle part. Supply polymer (polyolefin resin). Then, a molten polymer is extruded from a concentric die and cooled and solidified in a drafted state to obtain unstretched hollow fibers. Next, this unstretched hollow fiber is stretched to make the inner layer and outer layer sandwiching the homogeneous layer of the intermediate layer porous. Thereby, a three-layer composite hollow fiber membrane having a homogeneous layer and a porous support layer (an inner layer and an outer layer) that support the homogeneous layer is obtained.

  In the stretching step for making the support layer porous, the stretching ratio may be determined according to the type of polymer used. Usually, the draw ratio is preferably 2 to 5 times that of undrawn fibers. If the draw ratio is 2 times or more, the porosity of the porous support layer is increased, and the gas permeability is improved. Moreover, if it makes it 5 times or less, the breaking elongation of a composite hollow fiber membrane will improve.

  In the stretching step for making the support layer porous, the stretching temperature is not lower than the melting point (Tm) −20 ° C.) of the polymer constituting the homogeneous layer and not higher than (Tm + 40 ° C.) and lower than the Vicat softening point of the support layer. Preferably there is. The upper limits of the above ranges are significant in that defects due to disorder of the polyolefin resin molecules are less likely to occur. The upper limit is significant in that the support layer polymer is sufficiently porous to obtain sufficient performance as a degassing membrane.

  In the present invention, the polymer that is a potting resin (hereinafter referred to as “potting resin”) is the same polymer as that constituting the homogeneous layer, or a polyolefin-based resin that can be fused with the polymer constituting the homogeneous layer. Preferably there is. In particular, when the homogeneous layer is disposed in the inner layer or the intermediate layer of the hollow fiber membrane, it is preferable to melt the potting resin into the pores of the porous support layer and fuse it with the homogeneous layer. In this case, the viscosity of the potting resin may be set appropriately. Adhesion is improved when the polymer constituting the homogeneous layer and / or the potting resin is made of a polyolefin resin having a weight average molecular weight to number average molecular weight ratio (Mw / Mn) of 3.0 or less. This is preferable.

  The potting resin is preferably made of a polyolefin resin having a weight average molecular weight to number average molecular weight ratio (Mw / Mn) of 3 or less. When Mw / Mn is 3 or less, strength is improved while maintaining moldability, and mechanical defects (craze) are reduced. Moreover, since this polyolefin resin has few low molecular weight components, the molding temperature of the module part can be lowered and elution can be reduced. As a result, the properties such as moldability, mechanical strength, solvent resistance, and low elution required for the potting resin are satisfactorily satisfied without impairing the properties of the hollow fiber membrane.

  The potting resin preferably has a number average molecular weight (Mn) of 2000 or more. If Mn is 2000 or more, the mechanical strength and toughness of the potting portion are improved, and durability and impact resistance that can withstand long-term use are imparted.

  The potting resin is preferably a polyolefin resin obtained using a metallocene catalyst (single site catalyst). When using a metallocene catalyst, the molecular weight distribution is basically narrow compared to the case of using other catalysts (such as Ziegler-Natta catalyst), although it is the same type of polyolefin resin, low molecular weight components and A polyolefin resin having a low crystalline component and a low melting point can be obtained. The low melting point and low molecular weight components are advantageous in that the molding temperature can be lowered and elution can be reduced.

  The potting resin is preferably an ethylene / α-olefin copolymer, more preferably an ethylene / C3 to C20 α-olefin copolymer, and an ethylene / C6 to C8 α-olefin copolymer, like the polymer constituting the homogeneous layer. Coalescence is particularly preferred.

  The number average molecular weight (Mn) of the potting resin is preferably 2000 or more, and more preferably 10,000 or more. Each of these ranges is significant in terms of the mechanical strength and toughness of the potting part, and the durability and impact resistance that can withstand long-term use.

  The melting point (Tm) of the potting resin is preferably 50 to 130 ° C. This melting point is a value measured with a differential scanning calorimeter (DSC).

The potting resin similar to the polymer constituting the homogeneous layer, density (measured by JISK-7112 = ASTM D1505) is 0.940 g / cm ³ or less, 0.85 g / cm ³ or more polyolefin resin (particularly polyethylene Are preferred). More preferably 0.920 g / cm ³ or less on the upper limit value of the density, and more preferably 0.86 g / cm ³ or more for the lower limit.

  In the present invention, specific examples of the polymer constituting the module case (hereinafter referred to as “case material”) include olefin resins such as polyethylene and polypropylene. As a trade name of a commercially available polypropylene, for example, Wintech (manufactured by Nippon Polypro Co., Ltd.) can be mentioned. Examples of the polyethylene trade name include Creolex (manufactured by Asahi Kasei Chemicals Corporation) and affinity (manufactured by Dow Chemical Co., Ltd.).

  As the case material, a high molecular weight polymer having a low melt flow rate (MFR) is particularly preferable. Moreover, the polyolefin-type resin obtained using the metallocene catalyst like the thing mentioned previously is preferable. In this case, elution can be reduced, the melting point can be lowered while maintaining the strength, and adhesion and compatibility can be increased. The melt flow rate (MFR) of the case material is preferably 0.1 to 10 g / 10 min (JISK-7112). This MFR is a value measured according to JIS K7210 in the same manner as described above. Moreover, it is preferable that melting | fusing point of case material is lower than melting | fusing point of the polymer which comprises the support layer of a hollow fiber membrane.

  A hollow fiber membrane module can be manufactured by the following methods, for example.

  A plurality of hollow fiber membranes (for example, several hundreds) are bundled to form a converging body, and the converging body is inserted into a cylindrical module case. Then, the potting resin is filled with the potting resin while allowing the potting resin to penetrate into the pores of the porous body outside the hollow fiber membrane.

  As a filling method of the potting resin, for example, there is a method of filling the potting portion using a hot melt supply device or an extrusion molding machine. There is also a method in which potting resin powder is filled in a potting portion and melted and solidified.

  When potting resin powder is used, in order to improve the dispersibility of the powder, a dispersion composed of polyolefin resin powder and volatile organic solvent or water is prepared and dispersed in the potting molding processing section. It is preferable to supply a liquid. The dispersion liquid can be supplied to the potting molding processing section by, for example, applying or filling the potting molding processing section, or immersing the end of the hollow fiber membrane focusing body in the dispersion liquid.

  The operation of supplying the potting resin to the potting forming portion may be performed simultaneously with the formation of the plurality of hollow fiber membranes or after the formation of the converging body. In particular, it is preferable to uniformly fill the space between the outer surface of at least one end of the hollow fiber membrane bundle and the hollow fiber membrane in the potting molding processing part. The filling rate of the hollow fiber membrane with respect to the volume of the module case is preferably 20% or more and 60% or less.

  In a state where the potting resin powder is uniformly supplied to the potting molding processing portion, for example, heating may be performed while rotating the module case, that is, heating while applying centrifugal force for thickening.

  In the present invention, the molding temperature of the potting portion is a temperature below the melting point of the polymer constituting the support layer, preferably below the softening point. As a result, the porous structure of the support layer is maintained when the potting part is molded, and in particular when the support layer is on the outer surface of the hollow fiber membrane, the potting resin reaches the homogeneous layer through the pores of the support layer. If the temperature is equal to or higher than the Vicat softening point of the polymer constituting the homogeneous layer, the potting resin and the homogeneous layer are fused. In general, the Vicat softening point refers to the point where the melting point of each component is strictly different when a crystalline component or amorphous component is mixed like a polymer, and gradually changes to a liquid. From the point of starting fusion from the point of view, it is preferable that it is higher than the softening point of the polymer constituting the homogeneous layer from the viewpoint of improving air tightness and liquid tightness. More preferably, it is higher than the melting point of the polymer constituting the homogeneous layer from the viewpoint of improving the adhesiveness. From such a point, the molding temperature of the potting part is preferably 140 ° C. or lower.

  Further, the heating at the time of molding the potting part can be performed in stages. For example, first preheat at a temperature lower than the melting point of the case material and higher than the melting point of the potting resin to form a molten polymer, sufficiently impregnate the molten polymer in the pores of the support layer of the hollow fiber membrane, and then continuously or batch-process Thus, the potting can be formed by heating at a temperature below the softening point of the polymer constituting the support layer and above the melting point of the case material. Such a stepwise heating method is preferable from the viewpoint of preventing defects in the potting portion.

  The potting part is molded at the molding temperature as described above, and then the end face of the hollow fiber membrane in the vicinity of the potting part is cut to form the open end face. In this way, the hollow fiber membrane module of the present invention is obtained.

  FIG. 1 is a schematic view of the entire degassing hollow fiber membrane module. In the example shown in this figure, a plurality of degassing hollow fiber membranes 1 are bound to form a converging body, and at least one end (both in the figure) of the converging body of the hollow fiber membrane 1 is a potting portion 5. It is fixed by. The potting portion 5 is a member that fixes the converging body of the hollow fiber membrane 1 in the module case and seals (pots) the inside and the outside of the hollow fiber membrane 1 in a liquid-tight manner. Further, the end portion of the hollow fiber membrane 1 in the potting portion 5 is open. Therefore, when a liquid is supplied from one end connection port (liquid passage port) 6, the liquid passes through the inside of the hollow fiber membrane 1 and is discharged from the other end connection port 6. At that time, if the space outside the hollow fiber membrane 1 is vacuumed from the connection port (vacuum side) 7, the gas contained in the liquid flowing inside the hollow fiber membrane 1 becomes the space outside the hollow fiber membrane 1. The liquid is separated and moved and discharged from the connection port 7, and the liquid is deaerated.

  FIG. 2 is a schematic partial cross-sectional view of a potting portion of a module using a three-layer degassing hollow fiber membrane. The degassing hollow fiber membrane 1 shown in this figure is a three-layer composite membrane in which a homogeneous layer 3 (intermediate layer) is sandwiched between support layers 2 (an inner layer and an outer layer). The hollow fiber membrane 1 is fixed in the module case 4 by a potting portion 5. The potting resin constituting the potting portion 5 penetrates into the pores of the outer support layer 2 and is fused to the homogeneous layer 3. Thereby, the favorable adhesion fixation of the hollow fiber membrane 1 and the potting part 5 is implement | achieved.

  FIG. 3 is a schematic partial cross-sectional view of a potting portion of a module using a degassing hollow fiber membrane having a two-layer structure. The degassing hollow fiber membrane 1 shown in this figure is a two-layer composite membrane in which a homogeneous layer 3 (inner layer) is supported by an outer support layer 2 (outer layer). The potting resin constituting the potting portion 5 penetrates into the pores of the outer support layer 2 and is fused to the homogeneous layer 3. Thereby, the favorable adhesion fixation of the hollow fiber membrane 1 and the potting part 5 is implement | achieved.

  FIG. 4 is a schematic partial cross-sectional view of a potting portion of a module using a degassing hollow fiber membrane having a two-layer structure. The degassing hollow fiber membrane 1 shown in this figure is a two-layer composite membrane in which a homogeneous layer 3 (outer layer) is supported by an inner support layer 2 (inner layer). The potting resin constituting the potting portion 5 is fused to the homogeneous layer 3. Thereby, the favorable adhesion fixation of the hollow fiber membrane 1 and the potting part 5 is implement | achieved.

  Hereinafter, the present invention will be described in more detail based on examples. Each physical property was measured by the following method.

[Melting point (Tm)]
A differential scanning calorimeter (DSC) was used for measuring the melting point (Tm). Specifically, about 5 mg of sample was melted at 200 ° C. for 5 minutes, crystallized by cooling to 40 ° C. at a rate of 10 ° C./min, and then further heated to 200 ° C. at 10 ° C./min to melt. The melting point was determined from the melting peak temperature at the time and the melting end temperature.

[Vicat softening point]
The Vicat softening point is a temperature measured by ASTM D 1525-70 or JIS K7206. When a gauge with a 1 kg load is placed on the plastic surface and heated, the gauge tip is 1 mm in the plastic. It is expressed as the temperature when entering.

[Ratio of weight average molecular weight to number average molecular weight (Mw / Mn)]
It measured by the following conditions by gel permeation chromatography (GPC).
GPC measuring device: WATERS 150-GPC (manufactured by WATERS)
Temperature: 140 ° C
Solvent: 1,2,4-trichlorobenzene concentration: 0.05% (injection amount: 500 microliters)
Column: One Shodex GPC AT-807 / S, two Tosoh TSK-GEL GMH6-HT Dissolution conditions: 160 ° C., 2.5 hours Calibration curve: A polystyrene standard sample was measured, and a polyethylene conversion constant (0.48) ) And calculated in the third order.

[Melt flow rate (MFR)]
In accordance with JIS K7210, polyethylene is melt flow rate (MFR 2.16) (g) by measuring the mass of resin extruded in a strand form for 10 minutes at a load of 2.16 Kg at 190 ° C. using a melt indexer. / 10 min). In the case of polypropylene, the melt flow rate (MFR2.16) (g / 10 min) was determined by measuring the mass of the resin extruded in a strand shape at 230 ° C. for 10 minutes.

[density]
In accordance with JIS K7112, a sample obtained by heat-treating a strand obtained at the time of MFR measurement at 190 ° C. under a 2.16 Kg load at 100 ° C. for 1 hour and gradually cooling to room temperature over 1 hour was measured using a density gradient tube. .

<Example 1>
High-density polyethylene manufactured using a Ziegler-Natta catalyst for the inner layer and outer layer (support layer) using a hollow fiber manufacturing nozzle having discharge ports arranged concentrically to form a three-layer structure ( Product name Suntec B161, manufactured by Asahi Kasei Chemicals Corporation, MFR 1.1 g / 10 min, density 0.964 g / cm ³ , melting point 140 ° C., softening point 130 ° C., Mw / Mn = 10.3), intermediate layer (homogeneous layer) The ethylene / C8α-olefin copolymer (trade name AFFINITY PL1880G manufactured by Dow Chemical Co., Ltd., MFR 1.0 g / 10 min · 190 ° C., density 0.902 g / cm ^3, melting point 99 ° C., a softening point of 86 ℃, Mw / Mn = 2.2 , octene content of 30%) using a discharge temperature 180 ° C., spun at take-up speed of 100 m / min Te to obtain an undrawn hollow fiber. The inner diameter of the unstretched hollow fiber was 230 μm, and the three layers were arranged concentrically.

  This unstretched hollow fiber was annealed at 108 ° C. for 8 hours. Next, the film was stretched 1.25 times at 23 ± 2 ° C., subsequently stretched 4.4 times in a heating furnace at 70 ° C., and then subjected to a relaxation process of 0.4 times in a heating furnace at 100 ° C. It was provided and finally molded so that the total draw ratio was 4 times, and heat-stretched until the total draw amount was 4 times to obtain a composite hollow fiber membrane. This multilayer composite hollow fiber membrane had a three-layer structure in which a homogeneous membrane (non-porous thin film) was sandwiched between two porous layers.

When the air permeation rate of this composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) at room temperature (23 ± 2 ° C.) was 0.15 m / hr · Mpa, and the nitrogen permeation rate (Q _N2 ) was 0.07 m / hr · Mpa, and the separation factor (Q _O2 / Q _N2 ) was 3.0. Further, the separation factor of the polymer used for the homogeneous layer was maintained at 3.0. Furthermore, no leakage occurred even when a BCA (butyl carbitol acetate) solution was fed under pressure at 0.5 MPa.

200 hollow fiber membranes were bound to form a converging body and inserted into a module case. As the module case, an ethylene-octene copolymer produced by a metallocene catalyst (trade name AFFINITY PL1840G, manufactured by Dow Chemical Co., Ltd., MFR 1.0 g / 10 min · 190 ° C., density 0.909 g / cm ³ ; melting point 101 ° C., softening point 95 ° C., Mw / Mn = 2.3).

Potting resins include ethylene-octene copolymer (trade name AFFINITY GA1950, manufactured by Dow Chemical Co., Ltd., MFR 500 g / 10 min · 190 ° C., density 0.874 g / cm ³ , melting point 70 ° C., Mn 22000, A powder having an average particle diameter of 100 μm obtained by freeze-pulverizing Mw / Mn = 2.1) was used.

  And the said powder was supplied between the films | membranes of the one end part of a hollow fiber membrane focusing body, and it heat-melted and solidified at 105 degreeC, centrifuging. Next, the hollow fiber membrane module was obtained by cutting and opening the end of the hollow fiber membrane.

  One end of this hollow fiber membrane module was stopped, and the BCA liquid was fed under pressure at 0.5 MPa, and left in that state for 6 days at room temperature, but there was no chemical leak on the vacuum side (outside the degassing membrane). I couldn't.

<Example 2>
In the intermediate layer (homogeneous layer), an ethylene / C8α-olefin copolymer (trade name AFFINITY EG8100G, manufactured by Dow Chemical Co., Ltd., MFR 1.0 g / 10 min / 190 ° C.) produced with a metallocene catalyst. , Density 0.870 g / cm ³ , melting point 55 ° C., softening point 60 ° C., Mw / Mn = 2.0, octene content 35%), and the winding speed was changed to 90 m / min. Spinning was carried out in the same manner as in Example 1 to obtain an undrawn hollow fiber. The inner diameter of the unstretched hollow fiber was 200 μm, and the three layers were arranged concentrically.

  This unstretched hollow fiber was annealed in the same manner as in Example 1. Next, the film was stretched 1.25 times at 23 ± 2 ° C., subsequently stretched 4.4 times in a heating furnace at 70 ° C., and then subjected to a relaxation process of 0.4 times in a heating furnace at 100 ° C. It was provided and finally molded so that the total draw ratio was 4 times, and heat-stretched until the total draw amount was 4 times to obtain a composite hollow fiber membrane. This multilayer composite hollow fiber membrane had a three-layer structure in which a homogeneous membrane (non-porous thin film) was sandwiched between two porous layers.

When the air permeation rate of this composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) at room temperature (23 ± 2 ° C.) was 0.30 m / hr · Mpa, and the nitrogen permeation rate (Q _N2 ) was 0.10 m / hr · Mpa, and the separation factor (Q _O2 / Q _N2 ) was 3.0. Since the separation factor of 2.8 of the polymer used in the homogeneous layer was maintained, no leakage occurred even when a solvent (isopropyl alcohol) was passed through.

  Using this hollow fiber membrane, a hollow fiber membrane module was produced in the same manner as in Example 1 except that the heating and melting temperature while centrifuging was changed to 80 ° C.

  This hollow fiber membrane module was pressurized and fed with BCA solution and allowed to stand for 6 days in the same manner as in Example 1. No leakage of chemical solution was observed on the vacuum side (outside the degassing membrane).

<Example 3>
Using a hollow fiber manufacturing nozzle having discharge ports arranged concentrically to form a two-layer structure, high-density polyethylene (trade name Suntec B161) is used for the outer layer (support layer), and inner layer (homogeneous layer). A composite hollow fiber membrane was obtained in the same manner as in Example 2 except that an ethylene / C8α-olefin copolymer (trade name affinity (AFFINITY) EG8100G) was used. This composite hollow fiber membrane had a two-layer structure having a porous layer as an outer layer and a homogeneous layer as an inner layer.

  A hollow fiber membrane module was produced in the same manner as in Example 2 except that this hollow fiber membrane was used.

  This hollow fiber membrane module was pressurized and fed with BCA solution and allowed to stand for 6 days in the same manner as in Example 1. No leakage of chemical solution was observed on the vacuum side (outside the degassing membrane).

<Example 4>
Except for using ethylene / C8α-olefin copolymer (trade name affinity (AFFINITY) EG8100G) for the outer layer part (homogeneous layer) and high density polyethylene (trade name Suntech B161) for the inner layer part (support layer), A composite hollow fiber membrane was obtained in the same manner as in Example 3. This composite hollow fiber membrane had a two-layer structure with a homogeneous layer in the outer layer and a porous layer in the inner layer.

  A hollow fiber membrane module was produced in the same manner as in Example 2 except that this hollow fiber membrane was used.

  This hollow fiber membrane module was pressurized and fed with BCA solution and allowed to stand for 6 days in the same manner as in Example 1. No leakage of chemical solution was observed on the vacuum side (outside the degassing membrane).

<Example 5>
As a potting resin, Ziegler-Natta low-density polyethylene (trade name Sumikasen G807, manufactured by Sumitomo Chemical Co., Ltd., MFR 75 g / 10 min · 190 ° C., density 0.919 g / cm ³ , melting point 107 ° C., softening point 76 ° C., Mn 8600, A hollow fiber membrane module was produced in the same manner as in Example 1 except that powder having an average particle diameter of 100 μm obtained by freeze-pulverizing Mw / Mn = 11.3) was used and the processing temperature was 117 ° C.

  This hollow fiber membrane module was pressurized and fed with BCA solution and allowed to stand for 6 days in the same manner as in Example 1. No leakage of chemical solution was observed on the vacuum side (outside the degassing membrane).

<Example 6>
Polypropylene wax using a metallocene-based catalyst that can be fused to a polymer having a Mw / Mn of 3 or less and a homogeneous layer as a potting resin (trade name Ricocene PP1502, manufactured by Clariant Co., Ltd., density 0.87 g / cm ³ , melting point 82 ° C., softening point 72 ° C., Mn 2900, Mw / Mn = 2.31) was obtained by freeze-pulverizing powder with an average particle size of 100 μm, and the module processing temperature was 110 ° C. A hollow fiber membrane module was produced in the same manner as in Example 1.

  This hollow fiber membrane module was pressurized and fed with BCA solution and allowed to stand for 6 days in the same manner as in Example 1. No leakage of chemical solution was observed on the vacuum side (outside the degassing membrane).

<Example 7>
Polypropylene produced using a Ziegler-Natta catalyst for the inner layer and outer layer (support layer) using a three-layer nozzle (trade name FY6H, manufactured by Nippon Polypro Co., Ltd., MFR 1.1 g / 10 min. 230 ° C. , Density 0.90 g / cm ³ , melting point 170 ° C., softening point 160 ° C., Mw / Mn = 5.0), and ethylene-propylene copolymer (VERSIFY2200, Dow Chemical ( Co., Ltd., MFR 2.0 g / 10 min · 230 ° C., density 0.876 g / cm ³ , melting point 95 ° C., softening point 66 ° C., Mw / Mn = 2.3) Spinning was performed to obtain an unstretched hollow fiber. The inner diameter of the unstretched hollow fiber was 230 μm, and the three layers were arranged concentrically.

  The obtained undrawn yarn was drawn 1.25 times at 23 ± 2 ° C., and subsequently drawn by 3.4 times in a heating furnace at 130 ° C., and then in a heating furnace at 100 ° C. Then, a relaxation step of 0.4 times was provided, and finally, the composite hollow fiber membrane was obtained by molding so that the total draw ratio was 3 times. This multilayer composite hollow fiber membrane had a three-layer structure in which a homogeneous membrane (non-porous thin film) was sandwiched between two porous layers.

When the air permeation rate of this composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) at room temperature (23 ± 2 ° C.) was 0.12 m / hr · Mpa, and the nitrogen permeation rate (Q _N2 ) was 0.03 m / hr · Mpa, and the separation factor (Q _O2 / Q _N2 ) was 4.0. In addition, the separation factor of the polymer used in the homogeneous layer was maintained at 4.0. Further, no leakage occurred even when the BCA liquid was pressurized and fed at 0.5 MPa.

This hollow fiber membrane was bound in the same manner as in Example 1 to form a converging body and inserted into the module case. As the module case, polypropylene produced by a metallocene catalyst (trade name Wintech WFX4T, manufactured by Nippon Polypro Co., Ltd., MFR 7.0 g / 10 min · 230 ° C., density 0.90 g / cm ³ , melting point 125 ° C., softening point A case consisting of 115 ° C. and Mw / Mn = 2.8) was used.

  As the potting resin, a powder having an average particle diameter of 100 μm obtained by freeze-pulverizing the same polypropylene wax (trade name Ricosen PP1502) as in Example 7 was used.

  Then, the heating and melting temperature while centrifuging was changed to 125 ° C., and a hollow fiber membrane module was produced in the same manner as in Example 1.

  About this hollow fiber membrane module, MEK solution was pressure-fed at 0.4 MPa and allowed to stand for 6 days, but no leakage of chemical solution was found on the vacuum side (outside the degassing membrane).

<Comparative example>
Low density polyethylene produced using a Ziegler-Natta catalyst for the support layer (trade name Hi-Zex 2200J, manufactured by Prime Polymer Co., Ltd., MFR 5.2 g / 10 min · 190 ° C., density 0.964 g / cm ³ , melting point 135 ° C., Vicat softening point 130 ° C.) was used.

Low density polyethylene manufactured using a Ziegler-Natta catalyst for the inner layer portion (homogeneous layer) (trade name ULT XEX 20200J, manufactured by Prime Polymer Co., Ltd., MFR 18.5 g / 10 min · 190 ° C., density 0.918 g / cm ³ , melting point 120 ° C., Vicat softening point 94 ° C., Mw / Mn = 7.0). A composite hollow fiber membrane having a two-layer structure was produced in the same manner as in Example 3 to obtain a convergent body.

Potting resin includes ethylene-octene copolymer (trade name AFFINITY GA1950, manufactured by Dow Chemical Co., Ltd., MFR 500 g / 10 min · 190 ° C., density 0.874 g / cm ³ , melting point 70 ° C., softening point. A powder having an average particle diameter of 100 μm obtained by freeze-pulverizing 60 ° C., Mn 22000, Mw / Mn = 2.1) was used.

The powder was supplied between the membranes at each end of the hollow fiber membrane bundle. As the module case, an ethylene-octene copolymer produced by a metallocene catalyst (trade name AFFINITY PL1880G, manufactured by Dow Chemical Co., Ltd., MFR 1.0 g / 10 min · 190 ° C., density 0.909 g / cm ³ , melting point 99 ° C., softening point 86 ° C., Mw / Mn = 2.3).

  Inserted into the module case. While centrifuging, the module was prepared by heating and melting and solidifying at 90 ° C., which is a temperature higher than the melting point of the potting resin and lower than the softening point of the homogeneous layer polymer, and opening the end. Furthermore, when one end of this hollow fiber membrane module was stopped and the BCA solution was pressurized and fed at 0.5 MPa, a chemical leak was found on the vacuum side (outside the degassing membrane).

It is a schematic diagram of the whole hollow fiber membrane module for deaeration. It is a typical fragmentary sectional view of the potting part of the module using the hollow fiber membrane for deaeration of a three-layer structure. It is a typical fragmentary sectional view of the potting part of the module using the hollow fiber membrane for deaeration of a two-layer structure (an inner layer is a homogeneous layer, an outer layer is a support layer). It is a typical fragmentary sectional view of the potting part of the module using the hollow fiber membrane for deaeration of a two-layer structure (an inner layer is a support layer and an outer layer is a homogeneous layer).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Degassing hollow fiber membrane 2 Degassing hollow fiber membrane support layer 3 Degassing hollow fiber membrane homogenous layer 4 Module case 5 Potting part 6 Connection port (fluid port)
7 Connection port (vacuum side)

Claims (4)

A plurality of deaeration hollow fiber membranes having a porous support layer and a non-porous homogeneous layer are bundled, and the potting resin polymer is melted at the binding end of the hollow fiber membrane, and then cooled. In the method for producing a degassing hollow fiber membrane module for forming a potting portion for liquid-tight potting the inside and outside of the hollow fiber membrane in the module case,
The polymer that is the potting resin by heating at a temperature that is equal to or higher than the Vicat softening point of the polymer that constitutes the homogeneous layer, the melting point of the polymer that is the potting resin, and less than the melting point of the polymer that constitutes the support layer. And a polymer constituting the homogeneous layer and the polymer that is the potting resin are fused together to produce a hollow fiber membrane module for degassing.   The method for producing a hollow fiber membrane module for degassing according to claim 1, wherein the polymer constituting the homogeneous layer and the polymer which is a potting resin are made of the same polyolefin resin.   The polymer constituting the homogeneous layer, the polymer which is a potting resin, or both are made of a polyolefin resin having a ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) of 3.0 or less. Of producing a hollow fiber membrane module for degassing. The polymer, which is a potting resin, is preheated to a molten polymer at a temperature below the melting point of the polymer constituting the module case and above the melting point of the polymer, which is a potting resin, and is melted in the pores of the support layer of the hollow fiber membrane. Impregnating the polymer;
The hollow fiber membrane module according to any one of claims 1 to 3, further comprising, after the impregnation, a step of heating at a temperature below the softening point of the polymer constituting the support layer and above the softening point of the polymer constituting the module case. Manufacturing method.

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