JP2009112896A - Degassing composite hollow fiber membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a degassing composite hollow fiber membrane which does not occur the leakage of liquid chemicals during degassing, is excellent in solvent resistance and low elution property, and can suppress the production of foreign matter such as a crystalline molecule complex while keeping large permeability of gas such as oxygen or nitrogen even in the degassing composite hollow fiber membrane having large surface area in contact with ink liquid. <P>SOLUTION: The degassing hollow fiber membrane includes a homogeneous membrane having gas permeability, and a porous support layer supporting the homogeneous membrane, wherein the amount of an oxidation inhibitor is ≤0.005 mass%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is, for example, a polyolefin-based degassing for degassing a dissolved gas while suppressing precipitation of foreign matters in a manufacturing process of an ink-jet ink and a resist solution mainly composed of an aqueous solution or an organic solvent and a printer flow path. The present invention relates to a composite hollow fiber membrane.

  In the liquid crystal or plasma display manufacturing process, if bubbles are mixed in the supplied chemical solution, problems such as processing spots occur. In particular, recent liquid crystals and plasma displays are required to have a large screen and high definition.

  As a countermeasure against them, a manufacturing method using an ink jet method has been developed. The ink jet method is a method of recording characters and images (hereinafter sometimes simply referred to as “images”) on the surface of a recording medium by ejecting ink compositions as small droplets from fine nozzles. As an ink jet recording method, an electric signal is converted into a mechanical signal using an electrostrictive element, and the ink composition stored in the nozzle head part is intermittently ejected to record characters and images on the surface of the recording medium. The ink composition stored in the nozzle head part is rapidly heated at a part very close to the ejection part to generate bubbles, and ejected intermittently by volume expansion due to the bubbles, and characters and images are printed on the surface of the recording medium. A recording method has been put to practical use.

  In particular, in the state where bubbles are mixed in the ink liquid or the resist liquid, pattern defects may occur even in the ink jet system. It is thought that the cause of mixing of bubbles is that the chemical liquid is pumped to the discharge nozzle by nitrogen gas.

  That is, since the pressure applied to the chemical liquid returns to the atmospheric pressure when the chemical liquid is discharged from the discharge nozzle, the dissolved gas in the chemical liquid becomes supersaturated, and the supersaturated portion becomes bubbles. Therefore, there is a demand for a technique for reducing the amount of dissolved gas by a membrane-type degassing method and suppressing the generation of bubbles in the chemical solution pressure feeding process. As a hollow fiber membrane used for degassing a dissolved gas in a solvent, for example, Patent Document 1 discloses a three-layer hollow fiber made of a gas selective permeable homogeneous membrane coated on both sides with a hydrophobic porous membrane. A membrane is disclosed.

  Patent Document 2 exemplifies linear low density polyethylene as a material for the homogeneous film. Patent Document 3 discloses a hollow fiber membrane having a non-porous layer from the outer surface made of poly-4-methylpentene-1 to a depth of about 1 μm.

  It has been found that when an elastomer resin containing a large amount of an antioxidant is used for the ink contact member, a crystalline molecular complex may be formed upon contact with the ink. Since this crystalline molecular complex is brittle and breaks into a needle shape, it passes through a filter for trapping foreign matter and clogs the minute flow path of the nozzle head, causing abnormal discharge.

  In Patent Documents 4 and 5, an antioxidant contained in the ink filling device or ink jet printer structural material reacts to form a crystalline molecular complex and clogs the ejection part of the ink head. It is disclosed that the amount of antioxidant is specified as a measure against the phenomenon.

Generally, a hollow fiber membrane for deaeration is obtained with practical deaeration performance by increasing its surface area. When the surface area is increased, the deaeration performance can be improved. However, since the amount of the antioxidant that bleeds out from the resin surface increases, stricter control than normal piping is required.
Japanese Patent Laid-Open No. 5-185067 Japanese Patent Laid-Open No. 11-47565 JP-A-6-335623 JP 2006-15564 A JP 2006-28325 A

  As an example of a degassing film made of polyolefins that is often used for degassing ink jet inks, a film using linear low density polyethylene described in Patent Document 2 can be mentioned. Since this resin has a low gas permeability coefficient, it is necessary to form a very thin film of 0.3 μm or less in order to obtain a practically effective dissolved gas permeation flow rate. When such a thin homogeneous film is formed, the mechanical strength is lowered, and pinholes are easily generated.

  Moreover, although the deaeration film | membrane using the poly 4-methylpentene-1 of patent document 3 has high gas permeation | permeation performance, since it is weak to oxidation, it is necessary to increase the usage-amount of antioxidant. As a result, the antioxidant eluted in the ink liquid (bleed out) and the components of the ink liquid may react to clog the elements of the ink jet head.

  Further, the amount of the antioxidant for preventing clogging described in Patent Document 4 and Patent Document 5 relates to the production and filling equipment for ink-jet ink liquid or the piping equipment and structure of an ink-jet printer, Since it is not based on a particularly large surface area such as a degassing membrane, it is not necessarily applicable to a degassing membrane.

  The object of the present invention is to prevent contact with ink liquid while maintaining the high permeation flow rate of gas such as oxygen and nitrogen without causing leakage of chemical liquid at the time of deaeration, excellent solvent resistance and low elution property. Another object of the present invention is to provide a degassing composite hollow fiber membrane in which the generation of foreign matter such as a crystalline molecular complex is suppressed even in a degassing composite membrane having a large surface area.

  The present invention relates to a degassing composite hollow fiber membrane having a homogeneous membrane having gas permeability and a porous support layer for supporting the homogeneous membrane, and the antioxidant amount is 0.005% by mass or less, or antioxidant. A degassing composite hollow fiber membrane characterized by not containing an agent.

  ADVANTAGE OF THE INVENTION According to this invention, the production | generation of foreign materials, such as a crystalline molecular complex, can be suppressed, maintaining the characteristic calculated | required by the composite hollow fiber membrane for deaeration. Therefore, for example, the deterioration of the ink and the generation of foreign matter are suppressed in the degassing hollow fiber membrane module having a large surface area in the piping of the ink jet printer and the ink liquid production apparatus. Prevents clogging and enables stable printing.

  Generally, deaeration performance is improved by increasing the surface area of the degassing hollow fiber membrane. However, when the surface area is increased, the amount of components that bleed out from the resin surface also increases. Therefore, it is considered that stricter management is required for the degassing composite hollow fiber membrane than ordinary piping.

  In the present invention, the content of the antioxidant contained in the entire composite hollow fiber membrane having a homogeneous membrane and a porous support layer is 0.005% by mass or less (based on 100% by mass of the entire hollow fiber membrane). Thus, the object is achieved. Furthermore, the content of the antioxidant is preferably 0.001% by mass or less.

  Further, the amount of the antioxidant of the polyolefin resin constituting the porous support layer is preferably 0.001% by mass or less (based on 100% by mass of the porous support layer). This is because since the support layer is made porous, not only the outer surface area of the membrane but also the surface area including the porous interior is remarkably large, and the influence of the amount of antioxidant is relatively large.

  On the other hand, the amount of the antioxidant of the polyolefin resin constituting the homogeneous film is preferably 0.02 to 0.05% by mass (based on 100% by mass of the homogeneous film), and more preferably 0.02 to 0.03% by mass. Homogeneous membranes do not have a porous structure, so the area in contact with the liquid is small, and since the surface is coated with a porous support layer, the substantial surface area is small, and the influence of the amount of antioxidant is relatively small. Few. In addition, compared to high-density polyethylene generally used for the porous support layer, polyolefin resins (polyethylene resins and the like) used for the homogeneous membrane have low heat resistance. Therefore, when it is necessary to spin both polymers under the same temperature condition, the thermal degradation of the polyethylene-based resin of the homogeneous film tends to proceed, and the productivity is likely to deteriorate or the performance tends to deteriorate. Therefore, by containing 0.02 to 0.05 mass% (more preferably 0.02 to 0.03 mass%) of the antioxidant in the polyethylene resin constituting the homogeneous film, thermal deterioration is suppressed, and more It is possible to obtain a degassing composite hollow fiber membrane with high gas permeation performance by combining with a polymer having a large melting point difference while being able to withstand melt spinning under severe temperature conditions and significantly reducing the amount of antioxidant elution of the entire membrane. it can.

  There is no restriction | limiting in particular regarding the kind of antioxidant used for polyolefin resin which comprises a homogeneous film, A well-known thing can be used. Specific examples thereof include hindered phenol-based, phosphite-based, sulfur-based, phosphorus-based, and antioxidants that combine these. As a method for adding the antioxidant, any method may be used as long as it can be mixed uniformly.

  If necessary, additives such as UV absorbers, lubricants, antiblocking agents, colorants, flame retardants, and the like can be added to the polyolefin resin constituting the homogeneous film as long as the object of the present invention is not impaired. .

  The melt flow rate (MFR) of the polyolefin resin constituting the homogeneous film is preferably 0.1 to 5 g / 10 min · 190 ° C., more preferably 0.3 to 2 g / 10 min · 190 ° C. The upper limit of each range of MFR is sufficient to prevent the fluidity of the polymer and the uniformity of the thickness of the homogeneous membrane due to the flow of the resin for the homogeneous membrane to the support layer. Significant in terms of maintenance. 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 ASTM E1238 E condition.

  The ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) (polydispersity) of the polyolefin resin constituting the homogeneous film is preferably 3.0 or less. This increases the crazing resistance while maintaining the formability of the homogeneous film. Further, if a resin having a relatively narrow molecular weight distribution is used, the proportion of low molecular weight components is reduced, and high solvent resistance, engine oil resistance, solvent extraction resistance, tallow resistance, and the like are improved.

  The polyolefin-based resin constituting the homogeneous film is preferably a polymer 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.

  The polyolefin resin constituting the homogeneous film 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 thereof include ethylene / α-olefin copolymer, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), linear ultra low density polyethylene (VLDPE), Polypropylene, 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 copolymer, ethylene / methyl methacrylate copolymer, modified polyolefin (for example, olefin homopolymer or copolymer and unsaturated carboxylic acid such as maleic acid or fumaric acid, acid anhydride, ester, metal salt, etc. Reaction product) and the like. Among polyolefin resins, polyethylene resins are particularly preferable.

As the polyolefin resin constituting the homogeneous film, in particular a density (measured by JISK-7112 = ASTM D1505) is 0.910 g / cm ³ or less, 0.85 g / cm ³ or more resins. If the density is within this range, the oxygen permeability of the homogeneous membrane can be further increased, and a practically suitable melting point or softening point is obtained. Specific examples of such polyethylene-based resins include HDPE, LDPE, LLDPE, VLDPE, and (co) polymers mainly composed of ethylene obtained using the metallocene catalyst.

  Such a polyethylene resin is characterized by a low softening temperature and a narrow molecular weight distribution. From the correlation with the density, the melting point (Tm) of the polyethylene resin is preferably 40 to 100 ° C. or less. Tm is a value measured with a differential scanning calorimeter (DSC).

  Among the metallocene catalyst-based polyethylene resins, an ethylene / α-olefin copolymer is effective as a gas-permeable member. A typical example is an ethylene / α-olefin copolymer 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.

  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.

  The composite membrane constituting the hollow fiber membrane may be a two-layer composite membrane of a homogeneous membrane and a porous support layer, or a three-layer composite membrane in which a homogeneous membrane is sandwiched between porous support layers. .

  The thickness of the homogeneous film is preferably 0.5 to 10 μm. When this is 0.5 μm or more, pressure resistance during use is improved, and when it is 10 μm or less, gas permeability is improved.

  Regarding the thickness of the porous support layer, the thickness of one layer in the case of the two-layer composite membrane and the thickness of one layer of the inner layer or the outer layer of the three-layer composite membrane are preferably 10 to 200 μm. If this 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 porous support layer is generally composed of a polyolefin resin, and is preferably composed of a polyethylene resin such as high-density polyethylene. The mass ratio of the porous support layer and the homogeneous membrane is preferably in the range of 90/10 to 99/1.

  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 material can easily 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 porosity and pore size of the porous 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.

  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 polyethylene, 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 film is melted to the intermediate layer nozzle part. Supply polymer (polyethylene 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 the outer layer sandwiching the homogeneous membrane of the intermediate layer porous. Thereby, a three-layer composite hollow fiber membrane having a homogeneous membrane and a porous support layer (inner layer and outer layer) that supports the homogeneous membrane 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 process for making the support layer porous, the stretching temperature is not lower than the melting point (Tm) of the polymer constituting the homogeneous film, not lower than 20 ° C. and not higher than (Tm + 40 ° C.), and lower than the Vicat softening point of the supporting layer. It is preferable. Furthermore, about a lower limit, (Tm-10 degreeC) or more is especially preferable. The upper limit of each of the above ranges is significant in terms of obtaining sufficient performance as a degassing membrane in order to make the support layer polymer sufficiently porous while making it difficult for defects due to molecular disturbance of the polyolefin resin to occur. There is.

  A method for producing the composite hollow fiber membrane, comprising a stretching step for making the support layer porous, and a relaxation temperature in the stretching step is equal to or higher than a melting point (Tm) ° C. of a polymer constituting the homogeneous membrane , (Tm + 60 ° C.) or less is significant in that defects due to disorder of the polyolefin resin molecules are less likely to occur.

  Further, when the relaxation ratio for suppressing the shrinkage rate due to heat is 0.2 times or more and 0.5 times or less, and further 0.3 times or more and 0.45 times or less, the heat shrinkage after 75 ° C. × 8 hours. Since the rate can be reduced to 5% or less, it is more preferable in terms of module molding stability.

  Using the composite hollow fiber membrane described above, the chemical solution can be degassed satisfactorily. Usually, a composite hollow fiber membrane configured as a hollow fiber membrane module is used for deaeration. The hollow fiber membrane module, for example, bundles several hundreds of hollow fiber membranes and inserts them into a cylindrical housing, and allows the sealing material to penetrate between the outer porous pores of the composite hollow fiber membranes so that adjacent hollow fiber membranes are inserted. It can be manufactured by filling with a sealing material.

  Hereinafter, the present invention will be described in more detail based on examples. Each physical property was measured by the following method. In the following description, “%” means “% by mass”.

[Melting point (Tm)]
A differential scanning calorimeter (DSC) manufactured by Seiko Denshi Kogyo was used for the measurement of 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.

[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)]
The melt flow rate (MFR 2.16) (g / 10 min) was determined by measuring the mass of the resin extruded in a strand shape for 10 minutes under a load of 2.16 kg at 190 ° C. according to ASTM D1238 E condition.

[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>
An ethylene-octene copolymer produced by a metallocene catalyst (trade name: AFFINITY EG8100G, manufactured by Dow Chemical Co., Ltd., MFR 1.0 g / 10 min, density 0.870 g / cm ³ , melting point 55 ° C., Mw / Mn = 2.0, octene content 35%, antioxidant (trade name Irganox 1010) containing 0.02% were used.

The support layer (inner layer and outer layer) is a high-density polyethylene (trade name Suntech HD B161, MFR 1.35 g / 10 min, density 0.963 g / cm ³ , melting point 140 ° C., not containing antioxidants, conforming to the ordinance of milk and the like. ) Was used.

  Spinning was performed at a winding speed of 95 m / min using a three-layer composite nozzle in the above combination to obtain an unstretched hollow fiber in which the three layers were concentrically arranged.

  This unstretched hollow fiber was annealed at 108 ° C. Next, the film was stretched 1.25 times at 23 ± 2 ° C., and subsequently stretched 4.4 times in a heating furnace at 70 ° C., followed by a relaxation process of 0.4 times in a heating furnace at 100 ° C. And finally, it shape | molded so that the total draw ratio might be set to 4 times, and it heat-stretched until the total amount of stretch became 4 times, and obtained the 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.

<Example 2>
An ethylene-hexene copolymer (trade name EVOLUE SP0510, manufactured by Prime Polymer Co., Ltd., MFR 1.2 g / 10 min, density 0.903 g / cm ³ ) produced by a metallocene catalyst on the homogeneous membrane (intermediate layer) part. A melting point of 98 ° C., Mw / Mn = 2.0, containing an antioxidant (trade name: Irganox 1076) containing 0.03%, and the winding speed was changed to 90 m / min. Thus, an unstretched hollow fiber having three layers arranged concentrically was obtained.

  This unstretched hollow fiber was annealed and stretched in the same manner as in Example 1 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.

<Comparative Example 1>
An ethylene-propylene copolymer (trade name VERSIFY2000, manufactured by Dow Chemical Co., Ltd., MFR 2 g / 10 min, density 0.888 g / cm ³ , melting point 120 ° C., Mw / Mn = 2, An antioxidant (trade name: Irganox 1010) containing 0.05% was used.

For the support layer (inner layer and outer layer), polypropylene (trade name NOVATEC FY6H, manufactured by Nippon Polypro Co., Ltd., MFR 1.9 g / 10 min, density 0.90 g / cm ³ , melting point 170 ° C., Mw / Mn = 5, antioxidant) (Containing 0.06% of an agent).

  Spinning was performed at a winding speed of 90 m / min using a three-layer composite nozzle in the above combination to obtain an unstretched hollow fiber in which the three layers were concentrically arranged.

  This unstretched hollow fiber was annealed at 140 ° C. Next, the film was stretched by 1.25 times at 23 ± 2 ° C., and subsequently heat-stretched in a 120 ° C. heating furnace until the total stretching amount became 3.3 times. The relaxation process of 3 times was implemented, and it shape | molded so that the total draw ratio might finally become 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.

<Comparative example 2>
In the part of the homogeneous membrane (intermediate layer), poly-4-methylpentene-1 (trade name TPX MX002, manufactured by Mitsui Chemicals, MFR 21 g / 10 min, density 0.835 g / cm ³ , melting point 222 ° C., Mw / Mn = 10. Antioxidant (trade name: Irganox 1010) containing 0.18% was used.

For the support layer (inner layer and outer layer), poly-4-methylpentene-1 (trade name TPX RT31, manufactured by Mitsui Chemicals, MFR 26 g / 10 min, density 0.833 g / cm ³ , melting point 237 ° C., Mw / Mn = 10 and 0.18% antioxidant).

  Spinning was performed at a winding speed of 45 m / min using a three-layer composite nozzle in the above combination to obtain an unstretched hollow fiber in which the three layers were concentrically arranged.

  This unstretched hollow fiber was annealed at 200 ° C. Next, the film was stretched by 1.25 times at 23 ± 2 ° C., and subsequently heat-stretched in a heating furnace at 200 ° C. until the total stretching amount was 2.2 times, and 0.2 times in a heating furnace at 220 ° C. The relaxation process was carried out, and molding was performed so that the total draw ratio was finally doubled. 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.

<Elution amount of antioxidant and its influence>
About each multilayer composite hollow fiber membrane of an Example and a comparative example, the density | concentration of antioxidant was measured. Specifically, 100 g of a sample was immersed in IPA (isopropyl alcohol) at 40 ° C. for 5 days, and the elution amount of the antioxidant in the IPA solution was measured. The measurement conditions are as follows.

[Conditions for measuring antioxidant concentration]
Quantitative analysis was performed using HPLC chromatogram.
Pretreatment: 1 g of a sample was precisely weighed and subjected to high-frequency extraction, the resin component in the extract was removed, and HPLC analysis was performed using this as a test sample.
Apparatus: HewlettPackard (HP), 1100 type.
Column: Reversed phase distribution system column.
Detection wavelength: UV210nm.
Mobile phase: Acetonitrile aqueous solution.

  Further, for each multilayer composite hollow fiber membrane of Examples and Comparative Examples, a sample (hollow fiber membrane) was immersed in 60 ° C. ink for 5 days by the same method as in Japanese Patent Application Laid-Open No. 2006-15564. The presence or absence of foreign matter was confirmed. Specifically, an electroformed metal filter having an opening diameter of 10 μm is placed on a mesh filter of a filtration bottle, and a certain amount of ink is dropped and filtered onto the electroformed metal filter under reduced pressure filtration. A foreign substance having a shape considered to be a molecular complex was visually observed and confirmed, and identified with an infrared absorptiometer (FT-IR) as necessary.

  Table 1 below shows the measurement results of the amount of the antioxidant dissolved in IPA and the evaluation results of the generation of foreign matter. Further, the content of the antioxidant (%) in each resin constituting the support layer and the homogeneous membrane (when the mass of each of the homogeneous membrane and the support layer is based on 100%) and the support layer and the homogeneous membrane The mass ratio (specifically, the nozzle discharge amount ratio during spinning) and the antioxidant content (%) in the entire hollow fiber membrane (when the mass of the entire hollow fiber membrane is based on 100%) are also shown together. . As is apparent from Table 1, in Examples 1 and 2, no foreign matter was generated and no antioxidant was eluted.

  The degassing composite hollow fiber membrane of the present invention reduces the amount of dissolved gas in aqueous solutions, organic solvents, and resist solutions in, for example, semiconductor production lines, liquid crystal color filter production lines, and ink jet printer ink production. Useful for deaeration applications. In particular, it is very useful for deaeration of a photoresist solution and a developer used for lithography in a semiconductor production line.

Claims (6)

  A degassing composite hollow fiber membrane having a homogeneous membrane having gas permeability and a porous support layer for supporting the homogeneous membrane, wherein the amount of antioxidant is 0.005% by mass or less. Careful composite hollow fiber membrane.   The composite hollow fiber membrane for deaeration according to claim 1, wherein the amount of antioxidant of the polyolefin resin constituting the porous support layer is 0.001% by mass or less.   The composite hollow fiber membrane for deaeration according to claim 1, wherein the amount of antioxidant of the polyolefin resin constituting the homogeneous membrane is 0.02 to 0.05 mass%.   The composite hollow fiber membrane for deaeration according to claim 1, wherein the mass ratio of the porous support layer and the homogeneous membrane is in the range of 90/10 to 99/1.   The composite hollow fiber membrane for degassing according to claim 1, wherein the polyolefin resin constituting the homogeneous membrane is a copolymer of ethylene and at least one α-olefin having 3 to 20 carbon atoms. The composite hollow fiber membrane for degassing according to claim 1, wherein the density of the polyolefin resin constituting the homogeneous membrane is 0.850 to 0.910 g / cm ³ .