Composite plane membrane

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a flat film suitable for degassing a chemical solution, and particularly for degassing a chemical solution (photoresist solution, developer, chemical solution for spin-on glass process, etc.) in a semiconductor manufacturing process, an ink for an inkjet printer, a liquid crystal, and an organic solvent. Regarding composite flat membranes.

【0002】

[Conventional technology]

In ultrapure water for semiconductor manufacturing, boiler drain water, and building water supply lines, if the dissolved oxygen concentration in the raw water is saturated, it is likely to cause oxidation, and the dissolved oxygen is degassed from this raw water by a hollow fiber membrane. However, it is desired to reduce the dissolved oxygen concentration. Such a degassing technique is described in Japanese Patent Application Laid-Open No. 03-169303. In this publication, a three-layer structure composite hollow fiber membrane using a silicon rubber thin film, a silicon-polycarbonate copolymer, a poly 4-methyl 1 penten, a perfluoroalkyl polymer or a segmented polyurethane as a homogeneous thin film between the porous membranes. Describes a technique for degassing dissolved oxygen in water. In the semiconductor manufacturing process, inconveniences such as treatment spots may occur due to the inclusion of air bubbles in the supplied chemical solution. For example, a photoresist solution is applied to a thin film laminated on a semiconductor wafer, exposed through a patterned mask, developed, and then etched to form a pattern on the thin film. When the liquid or the developing liquid is spin-coated on the semiconductor wafer, troubles such as pattern defects due to processing spots occur. In addition, if air bubbles are mixed in the cleaning liquid in the cleaning operation in the lithography process, cleaning spots may occur. The cause of air bubbles is that the chemical solution is pressure-fed to the discharge nozzle with nitrogen gas, so when it is discharged from the nozzle, the pressure applied to the chemical solution returns to atmospheric pressure, so the dissolved gas becomes supersaturated, and the supersaturated portion becomes bubbles. It is thought that it will be. If the dissolved gas concentration is reduced by a method such as a membrane method for this chemical pressure feeding step, the generation of such bubbles can be suppressed.

【0003】

The following methods are known as techniques for degassing dissolved gas of chemicals using membranes. 1. A method of degassing dissolved nitrogen in a chemical solution using a porous hollow fiber membrane having communication holes from the inner surface to the outer surface (Japanese Patent Laid-Open Nos. 08-243306, 09-94447, 09-94447) -7936, Japanese Patent Application Laid-Open No. 01-199607, Japanese Patent Application Laid-Open No. 64-7915, Japanese Patent Application Laid-Open No. 05-57478, Japanese Patent Application Laid-Open No. 05-45282, etc.). 2. A homogeneous hollow fiber membrane is used, which has a homogeneous thin film layer (thin film layer without communicating pores) on the surface layer and is supported by a porous support layer composed of the same polymer as the homogeneous thin film layer. , A method for degassing dissolved nitrogen in a chemical solution (Japanese Patent Laid-Open No. 09-94447, Japanese Patent Application Laid-Open No. 09-187629, Japanese Patent Application Laid-Open No. 06-273897, etc.). 3. A method of degassing dissolved nitrogen in a chemical solution using a non-porous (homogeneous) tube film made of a tetrafluoroethylene resin having excellent solvent resistance into a tube (Japanese Patent Laid-Open No. 08-153675, JP-A-08). -243306, Japanese Patent Application Laid-Open No. 09-7936, Japanese Patent Application Laid-Open No. 05-267149, Japanese Patent Application Laid-Open No. 07-31804, Japanese Patent Application Laid-Open No. 09-57008, Japanese Square Root Extraction 08-124875, Square Root Extraction 02-9160 Gazette, etc.). 4. A method of degassing dissolved nitrogen in a chemical solution using a two-layer structure composite hollow fiber membrane in which a homogeneous thin film is laminated on a porous support (Square root extraction, JP-A-08-243306, JP-A-08-243306). Japanese Patent Application Laid-Open No. 09-94447, Japanese Patent Application Laid-Open No. 64-63007). 5. A non-porous film made of fluororesin is sandwiched between a porous support layer made of fluororesin, and the layers are bonded and integrated to degas the dissolved nitrogen in the chemical solution. (Japanese Patent Laid-Open No. 64-63007).

【0004】

Further, in the liquid crystal encapsulation step, a technique for degassing both dissolved gas and air bubbles with a vacuum pump is disclosed in JP-A No. 10-170932 and JP-A-07-218921. It is considered that the same degassing technique as in the case of degassing with the semiconductor chemical solution described above can be applied to this step as well. Further, in an inkjet printer equipped with a piezo element head, dissolved gas such as dissolved oxygen and nitrogen in the ink filled in the head is bubbled when the piezo element of the head repeats pressurization and depressurization many times during ink ejection. It is known that the ink grows to the piezo element head and easily stays in the piezo element head, and bubbles are ejected when the ink is ejected, resulting in print omission. On the other hand, in an ink jet printer equipped with a thermal head, dissolved gas in the ink grows into bubbles while driving the head in the thermal cycle of rapid heating and cooling of the ink, and these bubbles tend to stay in the thermal head, and the ink It is known that printing omission occurs due to the ejection of air bubbles during ejection.

【0005】

As a means to prevent such print omissions, a printing technique is used to degas the dissolved gas in the ink by the film-type degassing methods a and b below, and then use this degassed ink to reduce print omissions. Are known. A method of providing a decompression space and an ink filling space in the head separated by a flat plate partition and degassing the dissolved gas in the ink by the diaphragm is disclosed in Japanese Patent Publication No. 07-37137. b. A technology that supplies raw ink to the inside of a hollow tube, decompresses the outside of the tube, selectively degass the dissolved gas in the ink through the tube, and then supplies this degassed ink to the head for printing. It is disclosed in Japanese Patent Application Laid-Open No. 05-17712. In this disclosure example, an example using a Teflon tube (thickness 1 μm) is described.

【0006】

[Problems to be Solved by the Invention]

Examples of the chemical solution containing water include a semiconductor developer, an ink for an inkjet printer, and a mixed solution of alcoholic water. In the case of these chemicals, the solution temperature may be lower than 30 ° C to reduce the gas solubility as much as possible. In such usage, the gas solubility of water tends to be lower than that of organic solvents over a wide temperature range, and water is suitable for lowering the concentration of dissolved gas, and the temperature of the solution is adjusted. This is because the lower the temperature, the lower the gas solubility. However, when the technique described in JP-A-03-169303 is applied to a chemical solution containing water, there are the following problems. When a silicon rubber thin film, a silicon-polycarbonate copolymer, a perfluoroalkyl polymer or a segmented polyurethane is used as the homogeneous thin film, the water vapor permeation flow rate is high as well as the oxygen permeation flow rate and the nitrogen permeation flow rate, and degassing is continuously performed. If so, condensed water droplets are formed on the opposite surface of the film due to dew condensation. This is the same situation as raw water leaking to the other side. In addition, the swelling of the membrane is remarkable with respect to alcohols, ethers, ketones, and esters in the chemical solution, the thin film is torn, and a large amount of solvent vapor is discharged to the secondary side (decompression side) of the membrane. In addition, when poly (4-methylpentene-1) is used as the homogeneous thin film, the glass transition region is around 30 ° C, so the film material becomes brittle in chemical solutions at lower temperatures, and the film is exposed to external pressure. Was torn, and raw water was likely to leak to the other side.

【0007】

Regarding the semiconductor manufacturing technology, there are the following problems when trying to apply the technologies 1 to 5 described in the conventional technology. 1. Method for degassing dissolved gas using a porous hollow fiber membrane (Japanese Patent Laid-Open Nos. 08-243306, 09-94447, 09-7936, 01-199607, Akira According to Japanese Patent Publication No. 64-7915, Japanese Patent Publication No. 05-57478, Japanese Patent Publication No. 05-45282, etc.), if the membrane material and the chemical solution are well wetted, the liquid to be treated is supplied from the primary side of the membrane to the pores. The liquid to be treated permeates and the liquid to be treated leaks from the secondary side (opposite surface) of the membrane, and degassing cannot be performed. This phenomenon was particularly remarkable when the chemical solution was a semiconductor chemical solution or an inkjet ink. 2. A method in which a homogeneous thin film layer having no communication holes is present on the surface layer, and the dissolved gas is degassed by an inhomogeneous hollow fiber membrane supported by a porous support layer (Japanese Patent Laid-Open No. 09-94447, JP-A-09). In Japanese Patent Application Laid-Open No. -187629 and Japanese Patent Application Laid-Open No. 06-273897), it is difficult to completely disturb the crystal orientation of the homogeneous thin film layer in the spinning process for producing the film, and some crystal orientation ordered structure is formed. Therefore, in the stretching and porosity step, pores communicating with the homogeneous thin film layer and the porous support layer are likely to be formed. In addition, pinholes were likely to occur in the homogeneous thin film layer due to mechanical rubbing even during handling after film production. Therefore, in such a membrane, after the liquid to be treated permeates into the porous pores, the liquid to be treated leaks from the pores and pinholes of the homogeneous thin film layer, and degassing cannot be performed. In particular, when the chemical solution was a semiconductor chemical solution or an inkjet ink, the leakage of the chemical solution was remarkable. 3. Method of degassing dissolved gas using a tube membrane made of tetrafluoroethylene resin (Japanese Patent Laid-Open Nos. 08-153675, 08-243306, 09-7936, 05-267149) In Japanese Patent Application Laid-Open No. 07-31804, Japanese Patent Application Laid-Open No. 09-57008, Japanese Patent Application Laid-Open No. 08-124875, Japanese Patent Application Laid-Open No. 02-9160, etc.), in addition to the low nitrogen permeation coefficient of the membrane material, Since the thickness of the tube used for degassing is thick, the nitrogen permeation flow rate is low (for example, nitrogen permeation flow rate = 0.5 × 10).^-11cm³/(cm² Pa · sec))), the dissolved gas was reduced to only about 90% of the saturation concentration even after degassing, which was insufficient as a practical degassing level. 4. A method of degassing dissolved nitrogen in a chemical solution using a two-layer structure composite hollow fiber membrane in which a homogeneous thin film is laminated on a porous support (Actual Kaihei 02-91601A, JP-A-08-243306), In Japanese Patent Application Laid-Open No. 09-94447, Japanese Patent Application Laid-Open No. 64-63007, etc.), both the homogeneous thin film material and the porous support material satisfy the solvent resistance and are chemically inert, so that both layers are adhered. It is difficult to do. For this reason, both layers are integrated by fusion, but pinholes are likely to occur in the homogeneous thin film in the fusion process. When a pinhole is generated, the liquid to be treated leaks from the pinhole, so that deaeration tends to be insufficient. 5. A non-porous film made of fluororesin is sandwiched between support layers made of fluororesin, etc., and the layers are adhered to each other, and the dissolved nitrogen in the chemical solution is degassed using a three-layer structure hollow fiber membrane integrated. In the method (Japanese Unexamined Patent Publication No. 64-63007), the film thickness of the non-porous film surface becomes thicker due to the layer thickness of the adhesive, and the gas permeation resistance becomes large, so that the gas substantially permeates the thin film. The flow rate was apt to be insufficient, and the degassing performance was apt to be insufficient in practice.

【0008】

In the liquid crystal encapsulation step, the same degassing technique as in the case of chemical degassing in the semiconductor manufacturing process described above can be applied, but the same problem has arisen. Attempts to apply the technique described in the prior art to the dissolved gas degassing method in inkjet printer ink have the following problems. In Japanese Patent Publication No. 07-37137, there is a limit to the film area that can be mounted on the head due to the quick drive of the inkjet printer head, and the disclosed film material has a permeation flow rate of oxygen and nitrogen of about 1. ~ 3 × 10^-10cm³/(cm² Pa · sec), which was small, and it was difficult to sufficiently degas the dissolved gas to be degassed. b. The film thickness of the tetrafluoroethylene tube used in the examples of JP-A No. 05-17712 is as thin as 1 to 2 μm. When the ink raw material is flowed through the film from the inside of the film, the film is expanded outward by the flow of the ink. The film thickness was very thin against this force, and the mechanical strength of the film was insufficient, so there was a high risk that the film would break and the liquid to be treated would leak out.

【0009】

The present invention has been made to solve the above problems, and an object of the present invention is to have a sufficient nitrogen permeation flow rate and oxygen permeation flow rate, a low water vapor permeation flow rate, and even if the chemical solution is degassed. An object of the present invention is to provide a flat film having excellent durability and suitable for degassing without causing liquid leakage.

【0010】

[Means for solving problems]

The composite flat membrane of the present invention is a flat membrane having a composite structure in which a homogeneous thin film is sandwiched between porous support layers, and the permeation flow rate ratio of the oxygen permeation flow rate / nitrogen permeation flow rate of the flat membrane is 1.1 or more. According to K7114, the rate of change of the permeation flow rate ratio after immersing the flat membrane in the chemical solution is within ± 10%. At this time, it is desirable that the weight change rate of the flat membrane after immersing the flat membrane in the chemical solution is within 0 to + 30% according to JIS K7114. In addition, the nitrogen permeation flow rate is 0.5 x 10^-9cm³/(cm² Pa sec) or more, and the oxygen permeation flow rate is 0.6 × 10^-9cm³/(cm² Pa sec) or higher is desirable. In addition, the water vapor permeation flow rate is 1 x 10.^-2g m / (m² Day) The following is desirable. As the porous support layer, any one selected from the group of polyethylene, polypropylene, poly (4methyl-1-pentene), poly (vinylidene fluoride) and polyoxymethylene is desirable.

【0011】

As a homogeneous thin film, a copolymer of (2,2 bistrifluoromethyl-4,5-difluoro-1,3 dioxol) and tetrafluoroethylene, or a polymer blend composed of a styrene-based thermoplastic elastomer and polyolephine can be used. desirable. Here, as the polyolefin, the density is 0.900 g / cm.³Among the following polyolefins, the styrene-based thermoplastic elastomer is a copolymer in which a styrene block polymer and at least one block polymer of butadiene, ethylene-butylene, isoprene or ethylene-propylene are linked, or butadiene, ethylene. -A random copolymer obtained by randomly polymerizing at least one of butylene, isoprene or ethylene-propylene and styrene is desirable. A fluorine-based thermoplastic elastomer is also desirable as the homogeneous thin film.

【0012】

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, for example, the composite flat membrane of the present invention has a structure in which both sides of a homogeneous thin film 2 having no pinholes or micropores are sandwiched between the porous support layers 1 and 1 without being adhered. The porous support layer 1 and the homogeneous thin film 2 are only arranged in contact with each other, but it is interesting that the composite membrane has a stable morphology even when used for degassing chemicals. When the porous support layer 1 and the homogeneous thin film 2 are bonded together with an adhesive, the gas permeability of the homogeneous thin film tends to decrease due to the adhesive layer. A decrease in gas permeability of a homogeneous thin film is inappropriate because it causes a decrease in degassing performance. Further, when the homogeneous thin film 2 and the porous support layer 1 are integrated by heat fusion without using an adhesive layer, a part of the thin film is locally melted by heat to generate micropores, and these micropores are formed. The porous support layer inside the membrane and the porous support layer outside the membrane communicate with each other through the pores, and when the chemical solution is degassed, the solution leaks, which is inappropriate.

【0013】

The composite flat membrane of the present invention has a permeation flow rate ratio of 1.1 or more, which is represented by an oxygen permeation flow rate / nitrogen permeation flow rate. The gas permeation flow rate is a value obtained by supplying pure oxygen or nitrogen to the membrane and measuring the permeation flow rate according to ASTM D1434. If the permeation flow rate ratio is 1.1 or more, proper degassing performance is exhibited in practice, but if the permeation flow rate ratio is smaller than 1.1, pinholes have already been formed in a part of the membrane. Correspond. In particular, when this value is smaller than 0.93, pinholes having a size close to the mean free path of oxygen and nitrogen molecules are formed in the entire homogeneous thin film, and the chemical solution easily leaks through these pinholes, which is inappropriate.

【0014】

In the present invention, the chemical resistance of the composite flat membrane is evaluated by the indexes of (Equation 1) and (Equation 2) according to the immersion method (immersion at 23 ° C for 7 days) according to JIS K7114.

[Number 1]

<img file="JP2000288366A_D0001.tif" />【0015】

In the composite flat membrane of the present invention, the rate of change of the permeation flow rate ratio represented by (Equation 1) after the flat membrane is immersed in a chemical solution according to JIS K7114 is within ± 10%. If the rate of change of the permeation flow rate ratio is within ± 10%, the homogeneous thin film has sufficient durability against the chemical solution. On the other hand, when the rate of change is greater than -10%, pinholes are formed in the homogeneous thin film, and when the rate of change is greater than + 10%, the mechanical strength of the homogeneous thin film is reduced due to swelling. And the solvent vapor is discharged to the secondary side of the film. The chemical solution used in the chemical solution immersion test in the present invention is a target solution that requires resistance depending on the use of the flat membrane.

【0016】

Examples of the porous support layer of the present invention include polyethylene, polypropylene, poly (4-methyl-1-pentene), polyvinylidene chloride, and polyoxymethylene. These polymers have high chemical resistance to the chemicals handled in the present invention, and the weight change is almost zero. The weight change rate represented by (Equation 2) of the composite pinhole film of the present invention substantially represents the weight change of the homogeneous thin film, and as described above, if the value is within 0 to + 30%, it swells. There is no pinhole formation due to the above, and the mechanical strength is maintained enough to withstand practical use, and no chemical leakage occurs. If the rate of change in weight is less than 0%, it corresponds to the case where the film dissolves and pinholes are formed, and liquid leakage occurs, which is inappropriate. When the rate of change in weight is greater than + 30%, the degree of swelling of the membrane is large and the mechanical strength is reduced, and the membrane is torn when degassed for a long time.

【0017】

As the degassing achievement level when degassing the dissolved nitrogen gas and oxygen gas in the chemical solution, the concentration of the dissolved nitrogen gas and oxygen gas in the chemical solution after degassing is generally 50% or less of the oxygen and nitrogen solubility under atmospheric pressure. It is necessary to. If this level is not reached, the dissolved gas in the drug solution tends to become bubbles when the drug solution is exposed to another decompression step, which is insufficient as the degassing level. In particular, in inkjet printer ink, a particularly high degassing level may be required to prevent print omission, and it is preferable that the degassing reaching level is 10% or less of the solubility under atmospheric pressure. Nitrogen gas permeation flow rate is 0.5 x 10 to degas to such a practically sufficient level.^-9cm³/(cm² Pa sec) or more is required, and the oxygen permeation flow rate is 0.6 × 10^-9cm³/(cm² Pa sec) or more was found to be necessary. If the permeation flow rate of oxygen and nitrogen is smaller than the above value, the target degassing achievement level is not reached.

【0018】

When the dissolved gas is degassed by the membrane with respect to the chemical solution containing water, if the water vapor permeation flow rate of the membrane is large, the water vapor that has passed through the membrane is sent to the decompression pump. When a pump such as an oil diffusion pump or a rotary pump is used as the decompression pump, mixing of water vapor into the pump is likely to cause a failure. Furthermore, the water vapor that has permeated the membrane condenses on the secondary side surface of the membrane, and this condensed water promotes the growth of mold and bacteria, which is not preferable in terms of hygiene. Such a membrane having high water vapor permeability is not suitable for degassing a chemical solution containing water. As a result of the examination by the present inventors, in order to avoid the above inconvenience, the water vapor permeation flow rate of the membrane is 1 × 10.^-2g m / (m² Day) It was found that it is preferable that it is less than or equal to. The water vapor permeation flow rate referred to in the present invention supplies moist air at 25 ° C and 70% RH to the membrane according to ASTM E96, reduces the pressure on the opposite side of the membrane to 10 KPa, and cools the amount of water vapor passing through the membrane. The amount of collected water is converted into the unit membrane area per day, and this value is multiplied by the thickness of the membrane. In the homogeneous thin film material of the present invention described later, the water vapor permeation flow rate is 1 × 10.^-2g m / (m² Day) It is less than or equal to.

【0019】

The film thickness of the homogeneous thin film is preferably in the range of 1 to 10 μm. If this film thickness is thinner than 1 μm, the pressure resistance tends to be insufficient during actual use. If it is thicker than 10 μm, gas permeability tends to be insufficient, depending on the material used. The thickness of the polyolefin-based porous support layer is preferably 10 to 50 μm, and the porosity of the support layer is 10 to 50 vol%. In the present invention, the porous support layer has one or more layers arranged on both sides of the homogeneous thin film. In order to improve the mechanical strength of the film, it is more preferable to arrange two or more layers on one side of the homogeneous thin film. If the thickness of the porous support layer is less than 10 μm, the mechanical strength tends to be insufficient. Further, if the total thickness of the homogeneous thin film is larger than 200 μm on one side, the flat film becomes too thick, and when the film is incorporated in the module, the volumetric efficiency of the film becomes low, which is inappropriate.

【0020】

The present inventors have found that the following three types of thermoplastic polymers are suitable as a homogeneous thin film material for degassing a chemical solution that satisfies the above-mentioned chemical resistance and gas permeability. The first material for a homogeneous thin film is a blend polymer composed of a styrene-based thermoplastic elastomer and a polyolefin. A blended polymer composed of a styrene-based thermoplastic elastomer and polyolefin can be formed into a homogeneous thin film with a thickness of 10 μm or less, and this thin film has excellent chemical resistance to chemicals, and the dissolved gas can be degassed to a practical level. Can be degassed by. The gas permeability coefficient and gas permeation flow rate are values obtained by supplying pure oxygen and nitrogen to the membrane and measuring the permeation flow rate in accordance with ASTM D1434. The density is the value measured by melting the polymer at 190 ° C., then slowly cooling the extruded strands under a load of 2.16 kg to room temperature, and measuring this sample by the density gradient tube method according to ASTM D1505.

【0021】

As the styrene-based thermoplastic elastomer, it is preferable to appropriately select and use it from the following two structures (A) and (B). (A) A block copolymer having at least one of a styrene polymer as a hard segment and a butadiene polymer, an ethylene-butylene copolymer, an isoprene polymer or an ethylene-propylene copolymer as a soft segment. (B) A random copolymer composed of at least one of butadiene, ethylene-butylene, isoprene and ethylene-propylene and two or more constituent units of styrene. The oxygen permeability coefficient and nitrogen permeability coefficient of these styrene-based thermoplastic elastomers are 0.6 × 10.^-13~3×10^-12cm (STP)³cm cm^-2 Sec^-1 Pa^-1Therefore, it is necessary to make the film thickness of the homogeneous thin film 10 μm or less in order to obtain a product having the target oxygen permeation flow rate and nitrogen permeation flow rate. However, the styrene-based thermoplastic elastomer has a high melt viscosity, and it is difficult to form it into a thin film by itself. On the other hand, a polymer blend composed of a styrene-based thermoplastic elastomer and a polyolefin (hereinafter referred to as a polyolefin / styrene-based thermoplastic elastomer) has a smaller melt viscosity than a styrene-based thermoplastic elastomer and can be formed into a thin film. it can.

【0022】

Melt-blending polyolefin with styrene-based thermoplastic elastomer tends to reduce the gas permeability coefficient, but the density is 0.900 g / cm.³It was found that the following polyolefins can be blended by melt blending without lowering the gas permeability coefficient. The polymer melt-blended in this way has an oxygen permeability coefficient and a nitrogen permeability coefficient of 0.6 × 10.^-13~3×10^-12cm (STP)³cm cm^-2 Sec^-1 Pa^-1Therefore, the thin film can be thinned in the melt spinning process, and a thin film having a film thickness of 5 μm to 1 μm can be obtained. The oxygen permeation flow rate and nitrogen permeation flow rate of this thin film are 0.6 × 10.^-9~3×10^-8cm (STP)³·cm^-2 Sec^-1 Pa^-1And the oxygen permeation flow rate / nitrogen permeation flow rate can be 1.1 or more.

【0023】

To achieve chemical resistance to chemicals, melt-blend polyolefin with styrene-based thermoplastic elastomer and IPN (Interpenetrating Polymer) It is useful to have a Network) structure. In this structure, a styrene-based thermoplastic elastomer molecular chain (a molecular chain whose styrene domain is a physical cross-linking point) and a polyolefin molecular chain (a molecular chain whose crystal region is a physical cross-linking point) penetrate each other. I am doing. It is considered that the interpenetrating structure of such a three-dimensional network structure suppresses dissolution and swelling in the chemical solution, and forms a molecular chain gap to the extent that gas molecules can pass through. It was found that such a structure can have a mixed composition ratio of the styrene-based thermoplastic elastomer and the polyolefin in the range of the styrene-based thermoplastic elastomer / polyolefin = 5/95 to 95/5 (wt%). The blended polymer of the present invention depends on the type of chemical solution to be degassed, but when it is more desirable to make the structure of the molecular chain an IPN structure, but gas permeability is more important than chemical resistance, the polymer The molecular chain structure of the blend can also be a non-IPN structure. The chemical resistance of the blended polymer thin film of the present invention is excellent due to the above structure, but it is also resistant to a solvent having a strong ability to dissolve a styrene-based thermoplastic elastomer (eg, a hydrocarbon). Is inferior. However, it has excellent chemical resistance to ethers, ketones, and alcohols, and is unlikely to cause any pinholes in practical use.

【0024】

When the block copolymer of (A) above is used as the styrene-based thermoplastic elastomer, the temperature dependence of the storage elasticity of this block copolymer is such that the glass transition due to the structural relaxation of the styrene segment is found to be around 100 ° C. The glass transition due to the structural relaxation of the soft segment is observed around -50 to -70 ° C. On the other hand, the temperature dependence of the storage elastic modulus of the (B) random copolymer does not show a clear glass transition point, and in the temperature range of -50 ° C to 50 ° C, it is higher than that of the above (A) block copolymer. It is flexible and even more flexible in thin films. However, since the cross-linking point composed of the styrene segment is not a clear domain structure, the burst durability against external pressure is slightly inferior. However, in both (A) and (B) above, when the thickness of the thin film is 5 μm to 1 μm, the temperature dependence of the elastic modulus is gradual in the temperature range of -50 ° C to 50 ° C where the dissolved gas is degassed. The film is flexible over a wide temperature range, has sufficient burst strength against external pressure, and is suitable for use as a thin film for degassing.

【0025】

In addition, the homogeneous thin film made of "polyolefin / styrene thermoplastic elastomer" has low water vapor permeability, which reduces the load on the vacuum pump on the secondary side of the film when removing the dissolved gas in the chemical solution containing water. Is also excellent. Specific examples of styrene-based thermoplastic elastomers include shell chemistry (USA) as a structure in which the hard segment constituting the block copolymer is a styrene polymer and the soft segment is a butadiene polymer or an ethylene-butylene copolymer. Commercially available "Clayton" can be used, and the company's "Califlex TR" can be used as the structure in which the soft segment is isoprene and ethylene-propylene. Examples of the random copolymer include Japanese synthetic rubber products "HSBR1320P" and "HSBR1910P", which are random copolymers of styrene and ethylene-butylene. On the other hand, polyolefin has a density of 0.900 g / cm.³The following are preferred. Specific examples of such polyolefins include attackic polypropylene, low-density polyethylene, ethylene-propylene copolymers, and ethylene-octene copolymers (for example, the trade name "ENGAGE" of DuPont-Dow Elastomer). ..

【0026】

These styrene-based thermoplastic elastomers and polyolefins are melt-mixed by a twin-screw extruder, and the extruded strands are cooled and solidified, and then pelletized to be used as a resin raw material for a homogeneous thin film. For polymer blends of styrene-based thermoplastic elastomers and polyolefins, commercially available products from Japan Synthetic Rubber Co., Ltd. (JSR) "DYNARON H4800N" and "DYNARON H4900N", and Dainippon Plastics Co., Ltd. products "MK Resin (MK-1, MK)" -2, MK-3, MK-5) can be exemplified. In this case, the porous support layer is appropriately selected from high-density polyethylene, isotactic polypropylene, polyoxymethylene, and highly crystalline poly 4 methylpentene 1 and used.

【0027】

The second homogeneous thin film material is a copolymer of (2,2 bistrifluoromethyl-4,5-difluoro-1,3 dioxol) and tetrafluoroethylene. This polymer is in a glassy state at room temperature but can be melt-spun. Assuming that the mixing ratio of (2,2 bistrifluoromethyl-4,5-difluoro-1,3 dioxol) and tetrafluoroethylene is 50/50 to 90/10 (mol%) and the thickness of the thin film is 1 to 5 μm. , Nitrogen permeation flow rate is 0.5 × 10^-9cm³/(cm² Pa sec) or more and oxygen permeation flow rate is 0.6 × 10^-9cm³/(cm² Pa sec) or more. When the copolymerization ratio of 2,2 bistrifluoromethyl-4,5-difluoro-1,3 dioxol is less than 50 mol%, the gas permeability is low and it is inappropriate. If the copolymerization ratio exceeds 90 mol%, the thin film tends to become brittle even at room temperature, which imposes practicality. If the film thickness is thinner than 1 μm, the thin film is torn during handling and pinholes are likely to occur. If it is thicker than 5 μm, the nitrogen permeation flow rate of the thin film is 0.5 × 10.^-9cm³/(cm² It tends to be smaller than Pa sec). With respect to this homogeneous thin film, it is preferable to appropriately select and use poly4-methyl-1-pentene, polypropylene, and polyvinylidene chloride as the material for the porous support.

【0028】

The third material for homogeneous thin films is a fluorinated thermoplastic elastomer. In the fluorine-based thermoplastic elastomer referred to in the present invention, the hard segment is a fluororesin and the soft segment is a fluororubber. Examples of the hard segment fluororesin include ethylene-tetrafluoroethylene copolymer or polyvinylidene chloride. Examples of the soft segment fluororubber include a vinylidene fluoride-hexafluoropropylene binary copolymer or a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer. The fluorine-based thermoplastic elastomer preferably has a glass transition point of -20 ° C to -10 ° C. Since there is a glass transition region in such a very low temperature region, the homogeneous thin film is not easily broken even if the chemical solution containing water is degassed at a low temperature. Specific examples of the fluorine-based thermoplastic elastomer are "Daiel Thermoplastic" manufactured by Daikin Industries (composition: ethylene-tetrafluoroethylene copolymer in the hard segment and vinylidene fluoride-hexafluoropropylene binary copolymer in the soft segment). ) Is illustrated. In this case, the porous support layer is preferably used by appropriately selecting from highly stereoregular polypropylene, highly crystalline poly (4methyl-pentene-1), polyvinylidene chloride and the like.

【0029】

The chemicals to be degassed by the composite flat membrane of the present invention include alcohols such as methanol, ethanol, isopropyl alcohol and butanol, organic solvents such as methyl ethyl ketone, ethyl cellosolve, ethyl lactate and propylene glycol monomethyl ether acetate, and chemical amplification. Positive photoresist solution, naphthoquinone diazide-based positive photoresist solution, semiconductor developer in which tetramethylammonium hydroxide is dissolved in water, ink for inkjet printers in which dyes are dispersed, inks for inkjet printers in which pigments are dispersed, and The liquid crystal can be mentioned. The chemically amplified positive photoresist solution contains ethyl lactate, which is a methacrylic acid resin having an alicyclic adamantyl group and a cyclic ketone (oxocyclohexyl) group in the side chain, or a copolymerization of a methacrylic acid ester of mevallolactone and methyl adamantyl methacrylate. It is a solution dissolved in propylene glycol monomethyl ether acetate. The naphthoquinone diazide-based positive photoresist is a solution in which a naphthoquinone diazide-based polymer is dissolved in ethyl lactate and propylene glycol monomethyl ether acetate. Inkjet printer ink is a solution in which dyes and pigments are dissolved in a mixed solvent such as water, ethylene glycol, isopropyl alcohol, and methyl ethyl ketone. Examples of the liquid crystal include cholesteric liquid crystal, and specific compounds include cholesterin chloride and cholesterin nonanoate. Table 1 shows examples of the solubility of oxygen, nitrogen, oxygen in the air, and nitrogen in the above chemicals. This table is based on the numerical values listed in the Chemical Handbook (Maruzen) and our measurement results. The measurement used a generally known gas chromatograph analysis method. The dissolved gas concentration described in the examples described later also uses the gas chromatograph analysis method.

【0030】

[table 1]

<img file="JP2000288366A_D0002.tif" />【0031】

The method for producing the composite flat film of the present invention is not particularly limited, but it can be obtained by, for example, a combination of a multilayer composite film manufacturing step by a laminated extrusion method and a stretched porous step. The device used for the laminated extrusion may be any device as long as it is a co-extrusion type laminated film extrusion device, and either a T-die type or a tubular type can be used. However, since the adhesion of each layer is important, it is preferable to adopt a method of laminating inside the die such as the multi-manifold method. As a specific example, a molten polymer for a support layer precursor (unstretched layer) is supplied to the outermost layer nozzle portion and the innermost peripheral nozzle portion of the slit-shaped composite structure nozzle base, and a homogeneous thin film is supplied to the intermediate layer nozzle portion. The molten polymer is supplied, the molten polymer is co-extruded from the slit-shaped mouthpiece, and the unstretched film is wound while being cooled and solidified under elongation stress. Next, the unstretched film is stretched by a conventionally known stretching method to make the support layer precursor porous. The draw ratio varies depending on the polymer used, but a range of 1.2 to 10 times that of the undrawn fiber is appropriate. If it is lower than 1.2 times, the porosity of the porous support layer becomes lower than the above-mentioned lower limit value, and sufficient gas permeability cannot be obtained. If it is larger than 10 times, the breaking elongation of the composite flat film is low and it tends to be a problem in practical use.

【0032】

Degassing of a chemical solution using the composite flat membrane of the present invention is usually carried out using a composite flat membrane formed as a flat membrane module. The type of module in which the composite flat membrane is formed is not particularly limited, but an example is a module in which a composite flat membrane is bundled in a spiral shape and inserted into a tubular housing, or a module in which a disc-shaped membrane is fixed with a frame and laminated. Is listed as. A method of supplying the chemical solution to the use point by the chemical solution degassing treatment device connected to the chemical solution supply nozzle 19, the flat membrane module 10, and the chemical solution tank 3 shown in FIG. 2 will be described. The supply method is not limited to this example, and other supply methods known so far can be applied. Nitrogen gas 20 is supplied from the nitrogen supply pipe 5 to the chemical solution 4 stored in the chemical solution tank 3 to pressurize the chemical solution, and the flat film is housed via the chemical solution supply pipe 6 using the nitrogen gas pressure as a driving force. It is supplied to the flat membrane module 10 deployed inside. At this time, the air drive valves 9 and 15 are opened, and the air drive valve 8 provided in the bypass pipe 7 and the air drive valve 17 provided in the degassed chemical solution supply pipe 18 are closed. The air-driven valve 16 opens until the chemical solution begins to flow and fills the flat membrane module 10, and closes when the chemical solution flows out from the bypass pipe 14. In the flat membrane module 10, the chemical solution is supplied to one side of the flat membrane 11, and the opposite side of the flat membrane on the chemical solution supply side is decompressed to a pressure of 100 Pa to 10 KPa by a decompression pump 13 connected to the deaeration port 12, and a predetermined value is obtained. Degas for the time. When the degassing is completed in this way, the degassed chemical solution is opened at the valve 17, the chemical solution is discharged from the nozzle 19 which is a use point, and a new chemical solution is sent to the flat membrane module 10. In this way, the degassed chemical solution is supplied to the use point.

【0033】

The composite flat membrane of the present invention is particularly suitable for degassing dissolved gas from a chemical solution in a semiconductor manufacturing process, a printer, a liquid crystal encapsulation step, a chemical solution manufacturing process, and the like.

【0034】

[Example]

[Example 1] 10% by weight of "Clayton G-1652" manufactured by Shell Chemical Co., Ltd. and 80% by weight of "Clayton G-1657" manufactured by Shell Chemical Co., Ltd. were used as the styrene-based thermoplastic elastomer, and "ENGAGE 8400" manufactured by DuPont-Dow Elastomer Co., Ltd. was used as the polyolefin. (Density 0.870 g / cm³) Weighed 10% by weight and melt-blended with a twin-screw kneader. Next, this melt blend polymer (glass transition region -55 to -40 ° C) is co-extruded from an annular die (slit width 0.7 mm) with a discharge diameter of 100 mm as an intermediate layer and Asahi Kasei's high-density polyethylene "B161" as an inner layer and an outer layer. Then, I picked it up with a draft ratio of 110. The obtained unstretched film was annealed at 115 ° C for 12 hr, then uniaxially stretched 1.3 times at room temperature, and then uniaxially stretched 2.5 times at 111 ° C. The innermost and outermost layers were made of porous polyethylene and an intermediate layer. A three-layer composite flat film, which is a homogeneous thin film, was obtained. Table 2 shows the dimensions, porosity, gas permeation characteristics, and chemical resistance test results of this flat membrane. The water vapor permeation flow rate in this example is 1.2 × 10^-3g m / (m² It was day).

【0035】

[Example 2] Du Pont's "Teflon AF1600" ((2,2 bistrifluoromethyl-4,5-difluoro-1,3 dioxol)) and tetrafluoro on the intermediate layer of the three-layer composite nozzle at a resin temperature of 270 ° C. A copolymer having a copolymerization ratio of 60/40 (mol%) with ethylene, a glass transition region of 155 to 160 ° C) is supplied, and the resin temperature is 270 ° C on both sides of the support layer. 1-Pentene was supplied and copolymerized from a T-die to obtain a three-layer composite film. This unstretched film was annealed at 220 ° C for 12 hr, stretched 1.3 times at room temperature, and then stretched 3 times at 111 ° C. The inner and outer layers were made of porous poly4-methyl-1-pentene and an intermediate layer. Obtained a three-layer composite flat film, which is a homogeneous thin film of "Teflon AF1600". Table 2 shows the dimensions, porosity, gas permeation characteristics, and chemical resistance test results of this flat membrane. The water vapor permeation flow rate in this example is 6.0 × 10.^-2g m / (m² It was day).

【0036】

[Example 3] Fluoroplastic elastomer (Daiel Thermoplastic T-630 manufactured by Daikin Industries, Ltd., glass transition region -20 ° C to -10 ° C) in the intermediate layer of the three-layer composite nozzle at a resin temperature of 200 ° C. ) Is supplied, and Mitsui Chemicals' high stereoregular isotactic polypropylene (High Pole CJ700) is supplied to the inner and outer layers at a resin temperature of 200 ° C. I got a film. This unstretched film was annealed at 150 ° C for 12 hr, stretched 1.3 times at room temperature, and then stretched 3 times at 145 ° C. The innermost and outermost layers were porous isotactic polypropylene, and the intermediate layer was A three-layer composite flat film, which is a fluoroelastomer homogeneous thin film, was obtained. Table 2 shows the dimensions, porosity, gas permeation characteristics, and chemical resistance test results of this flat membrane. The water vapor permeation flow rate in this example is 2.1 × 10^-4g m / (m² It was day).

【0037】

[Table 2]

<img file="JP2000288366A_D0003.tif" />【0038】

The types of chemicals in Table 2 are as follows. A: Isopropyl alcohol (IPA) B: Semiconductor developer C: Spin-on glass solution (isopropyl alcohol / tetraethoxysilane / water = 70/2/28) D: Inkjet printer ink E: Cholesteric liquid crystal (cholesterin chloride cholesterin nonanoate) [0039]

[Test Example 1: Degassing treatment and application of resist solution to semiconductor photoresist] Flats prepared in Examples 1 to 3 using a chemically amplified positive resist (manufactured by "APEX-E2405" SHIPLEY) as a chemical solution to be degassed. Using a membrane, the membrane area is 2 m²The membrane module of No. 2 was prepared and attached to the chemical degassing treatment device shown in Fig. 2. The air-driven valves 9, 15 and 16 were opened, and the chemically amplified positive resist solution (manufactured by "APEX-E2405" SHIPLEY) in the chemical solution tank 3 was supplied to one side of the flat membrane module 10 with nitrogen gas at 2 atm. After the flat membrane was filled with the chemical solution, the valve 16 was closed, and the side opposite to the supply side of the flat membrane (hereinafter referred to as the decompression side) was kept at 100 Pa and degassed for 30 minutes. The resist solution that has been degassed in this way is separated from the bypass 14 of the chemical solution supply line, the dissolved nitrogen concentration is measured, a new chemical solution is sent to the membrane module 10, and the degassed resist solution is siliconized from the nozzle 19. The resist solution was dropped onto the wafer, and the dropped resist solution was shaken off at a spin coater rotation speed of 3000 rpm to form a resist thin film (thickness 0.80 μm) on the wafer. After evaporating and drying the residual solvent in the resist thin film, it was observed with a scanning electron microscope whether or not defects considered to be irregularities due to bubbles were generated in the 100 μm × 100 μm region of the resist thin film surface. The results of this example are shown in Table 3.

【0040】

[Table 3]

<img file="JP2000288366A_D0004.tif" />【0041】

[Test Example 2: Exposure of semiconductor photoresist, deaeration treatment of developer, development treatment] The above-mentioned resist thin film was prebaked at 90 ° C for 60 seconds, and then a photomask was placed on the resist film to obtain KrF excimer laser light. Close contact exposure was performed. A module was prepared using the flat membranes prepared in Examples 1 to 3 described above (membrane area 2 m).²), Attach this to the developer supply line of the coater developer for semiconductor manufacturing, which is the same chemical supply line as in Fig. 2, and use 2 atmospheric nitrogen gas to make SHIPLEY developer "MF-321" (tetramethylammonium hydroxide aqueous solution, Nitrogen gas concentration in aqueous solution (50 ppm) was supplied to one side of the flat membrane at a flow rate of 1 L / min., And the other side of the supply side was kept at 100 Pa and degassed for 30 minutes. After the degassing was completed, a new developer was supplied to the membrane module, and the degassed developer was dropped onto the exposed surface from the discharge nozzle 19 for development. The degassed developer was separated from the bypass 14 of the chemical supply line shown in FIG. 2 and the dissolved nitrogen concentration was measured. The resist film obtained by this development process is afterbaked in a 120 ° C dry oven, and the 100 μm × 100 μm region of the developed surface is observed with a scanning electron microscope. The groove width 22 and land width of the resist film shown in FIG. 3 are observed. 21 and groove depth 23 were measured, and defective parts in development were observed. The results of this example are shown in Table 4.

【0042】

[Table 4]

<img file="JP2000288366A_D0005.tif" />【0043】

[Test Example 3: Deaeration treatment for isopropyl alcohol] A module was prepared using the flat membranes prepared in Examples 1 to 3 (membrane area 2 m).²), Attach this to the chemical supply line similar to Fig. 2, supply isopropyl alcohol to the membrane module with 2 atm nitrogen gas in the same way as in Test Example 2, and after filling one side of the flat membrane with isopropyl alcohol. , The decompression side of the membrane was kept at 100 Pa, and degassing was performed for 30 minutes. After the degassing was completed, new isopropyl alcohol was supplied to the membrane module, and the degassed isopropyl alcohol was dropped onto the silicon wafer from the discharge nozzle 19 to wash the silicon wafer. The degassed isopropyl alcohol was separated from the bypass pipe 14 of the chemical supply line shown in FIG. 2 and the dissolved nitrogen concentration was measured. The results of this example are shown in Table 5.

【0044】

[Table 5]

<img file="JP2000288366A_D0006.tif" />【0045】

[Test Example 4: Deaeration treatment for spin-on-glass solution] A module was prepared using the flat membranes prepared in Examples 1 to 3 (membrane area 2 m).²), Attach this to the chemical supply line similar to Fig. 2, and spin-on glass solution (solution composition; isopropyl alcohol (70 wt%) / tetraethoxysilane (2 wt%) in 2 atm nitrogen gas in the same manner as in Test Example 2). / Water (28 wt%)) was supplied to the membrane module, and after one side of the flat membrane was filled with a spin-on glass solution, the decompression side of the membrane was kept at 100 Pa and degassed for 30 minutes. After the degassing was completed, a new spin-on-glass solution was supplied to the film module, and the degassed spin-on-glass solution was dropped onto the silicon wafer from the discharge nozzle 19 to form an insulating film on the silicon wafer. The spin-on-glass solution after degassing was separated from the bypass pipe 14 of the chemical supply line shown in FIG. 2 and the dissolved nitrogen concentration was measured. Further, the formed insulating film was placed in a 150 ° C dry oven, the condensation reaction was allowed to proceed, and the 100 μm × 100 μm region of the insulating film surface was observed with a scanning electron microscope to observe whether or not there was a defect. The results of this example are shown in Table 6.

【0046】

[Table 6]

<img file="JP2000288366A_D0007.tif" />【0047】

[Test Example 5: Degassing treatment for ink for inkjet printer, printing test with degassing ink] A module was prepared using the flat films prepared in Examples 1 to 3 (film area 2 m).²), Five of these were connected in series, and the membrane module assembly was attached to the chemical supply system shown in Fig. 2. Inkjet printer cartridge ink (solvent composition; water 80wt%, ethylene glycol 5wt%, isopropyl alcohol 15wt%, dye-based ink) is supplied to one side of the film at a flow rate of 100mL / min. did. Then, the decompression side of the membrane was kept under a decompression of 100 Pa, and degassing was performed for 30 minutes in the same manner as in Test Example 1. Dissolved oxygen and nitrogen concentrations in the degassed ink that passed through the five modules were measured by sampling from the bypass pipe 14 shown in Fig. 2. Next, the degassed ink was filled into an ink cartridge container (holding the inside under reduced pressure to 100 Pa) from nozzle 19 in FIG. 2, and this cartridge was mounted on an inkjet printer (PM700C manufactured by Seiko Epson Corporation) to perform a printing test. .. The dot area was obtained from the image of the magnifying projector, and the print omission frequency defined by the following equation was calculated. When the frequency of print omissions is less than 1%, there are few print omissions, and high-quality printing is recognized by the naked eye.

【0048】

[Number 2]

<img file="JP2000288366A_D0008.tif" />【0049】

The results of this example are shown in Table 7.

【0050】

[Table 7]

<img file="JP2000288366A_D0009.tif" />【0051】

[Example 4] 10% by weight of "Clayton G-1652" manufactured by Shell Chemical Co., Ltd. and 80% by weight of "Clayton G-1657" manufactured by Shell Chemical Co., Ltd. were used as the styrene-based thermoplastic elastomer, and "ENGAGE 8400" manufactured by DuPont-Dow Elastomer Co., Ltd. (density) was used as the polyolefin. 0.870g / cm³) Weighed 10% by weight and melt-blended with a twin-screw kneader. Next, this polymer blend (glass transition region -55 to -40 ° C) was placed in the intermediate layer, and the three-layer structure sandwiching the intermediate layer with Asahi Kasei's high-density polyethylene "B161" as the support layer was used in Example 1. The film was taken out while co-extruding with the annular die that had been used and cutting a part of the annulus in the extruding direction. This unstretched film was annealed at 115 ° C for 12 hr, stretched 1.3 times at room temperature, and then stretched 5 times at 111 ° C. The support layers on both sides were porous polyethylene, and the intermediate layer was a homogeneous thin film. A layered flat film (thickness 71 μm) was obtained. Both the support layers on both sides of the porous layer had a thickness of 35 μm and a porosity of 50 vol%. The homogeneous thin film layer had a thickness of 1 μm. Oxygen permeation flow rate in this flat membrane is 5.0 × 10^-9cm³·cm^-2 Pa^-1 Sec^-1Met. Nitrogen permeation flow rate is 4.0 × 10^-9cm³·cm^-2 Pa^-1 Sec^-1Met. This flat membrane was immersed in a mixed solution of water / IPA = 50/50 (wt%) at 20 ° C for 7 days, and the oxygen permeation flow rate was 5.0 × 10.^-9cm³·cm^-2 Pa^-1 Sec^-1And the nitrogen permeation flow rate is 4.0 × 10^-9cm³·cm^-2 Pa^-1 Sec^-1The initial state was maintained, and the rate of change in the weight of the film was 0. Using the above three-layer flat membrane, the membrane area is 1 m.²A mixed solution of water / IPA = 50/50 (wt%) with a dissolved oxygen concentration of 8 ppm was supplied to one side of the flat membrane at a flow rate of 5 L / min., And the decompression side of the membrane was kept at 30 torr. Degassed. The dissolved oxygen concentration after degassing was 0.1 ppm. The water vapor permeation flow rate in this example is 1.7 × 10.^-3g m / (m² It was day).

【0052】

[Test Example 6] A membrane area of 1 m using the three-layered flat membrane prepared in Example 1.²A mixed solution of isopropyl alcohol and water in which 1 ppm of oxygen is dissolved (isopropyl alcohol / water = 60/40 wt%) is supplied to one side of the flat membrane at a flow rate of 5 L / min. The decompression side of the membrane was kept at 30 torr and degassing was performed. The dissolved oxygen concentration after degassing was 0.06 ppm.

[Example 5] 90% by weight of Japanese synthetic rubber product "HSBR1390P" (styrene content 30wt%) as a styrene-based thermoplastic elastomer, and "ENGAGE 8400" (density 0.870g / cm) manufactured by DuPont-Dow Elastomer as a polyolefin.³) Weighed 10% by weight and melt-blended with a twin-screw kneader. Next, this polymer blend (glass transition region -60 to -55 ° C) was placed in the intermediate layer, and melt shaping was performed with a three-layer structure in which the intermediate layer was sandwiched from both sides with Asahi Kasei's high-density polyethylene "B161" as the support layer. To obtain a three-layer composite film. This unstretched film was annealed at 115 ° C for 12 hr, stretched 1.3 times at room temperature, and then stretched 5 times at 111 ° C. The support layers on both sides were porous polyethylene, and the intermediate layer was a homogeneous thin film. A layered flat film (thickness 68 μm) was obtained. The thickness of both supporting layers of the porous layer was about 34 μm, and the porosity was 50 vol%. The homogeneous thin film layer had a thickness of 1.0 μm. In this flat membrane, the oxygen permeation flow rate is 7.4 × 10.^-9cm³·cm^-2 Pa^-1 Sec^-1, Nitrogen permeation flow rate is 2.0 × 10^-9cm³·cm^-2 Pa^-1 Sec^-1Met. This flat membrane was immersed in a mixed solution of water / IPA = 50/50 (wt%) at 20 ° C for 7 days, and the oxygen permeation flow rate was 7.4 × 10.^-9cm³·cm^-2 Pa^-1 Sec^-1And the nitrogen permeation flow rate is 2.0 × 10^-9cm³·cm^-2 Pa^-1 Sec^-1The initial state was maintained, and the rate of change in the weight of the film was 0. 1m using the above three-layer composite flat membrane²A mixed solution of water / IPA = 50/50 (wt%) with a dissolved oxygen concentration of 100 ppm was supplied to one side of the flat membrane at a flow rate of 5 L / min. Degassed. The dissolved oxygen concentration after degassing was 1.1 ppm. The water vapor permeation flow rate in this example is 2.2 × 10.^-3g m / (m² It was day).

【0053】

[Example 6] "MK resin MK-2F" (glass transition region -40 to -30 ° C) manufactured by Dainippon Plastics Co., Ltd. was used as a polymer blend composed of a styrene-based thermoplastic elastomer and polypropylene. This polymer alloy is placed in the intermediate layer, and the structure is such that the intermediate layer is sandwiched between Tosoh's high-density polyethylene "Niporon Hard 5110" as a support layer, and the molten resin is co-extruded from the annular die at a resin temperature of 190 ° C. A composite film was obtained at a draft ratio of 700 by taking out a part of the film while cutting it in the extrusion direction. This unstretched film was annealed at 115 ° C for 12 hr, stretched 1.2 times at room temperature, and then stretched twice at 111 ° C. Both support layers were porous polyethylene, and the intermediate layer was a homogeneous thin film. A layered flat film (thickness 70 μm) was obtained. The thickness of the porous layer was about 34 μm on both sides, and the porosity was 50 vol%. The homogeneous thin film layer had a thickness of 2.0 μm. This flat membrane was immersed in a mixed solution of water / IPA = 50/50 (wt%) at 20 ° C for 7 days, and the oxygen permeation flow rate was 7.5 × 10.^-9cm³·cm^-2 Pa^-1 Sec^-1And the nitrogen permeation flow rate is 2.0 × 10^-9cm³·cm^-2 Pa^-1 Sec^-1The initial state was maintained, and the rate of change in the weight of the film was 0. Membrane area 1 m using the above three-layer composite flat membrane²A mixed solution of water / IPA = 50/50 (wt%) with a dissolved oxygen concentration of 120 ppm was supplied to one side of the flat membrane at a flow rate of 5 L / min., And the decompression side of the membrane was kept at 30 torr. Degassed. The dissolved oxygen concentration after degassing was 1.7 ppm. This degassing operation was continued for one month, but there was no change in the dissolved oxygen concentration after degassing during this period. The water vapor permeation flow rate in this example is 1.6 × 10.^-3g m / (m² It was day).

【0054】

[Example 7] JSR's "DYNARON H4800N" (glass transition region is around -50 to -40 ° C) was used as a polymer blend consisting of a styrene-based thermoplastic elastomer and polypropylene. This polymer alloy is placed in the intermediate layer, and the structure is such that the intermediate layer is sandwiched from both sides with Tosoh's high-density polyethylene "Nipolon Hard 5110" as the support layer, and the molten resin is co-extruded from the annular die at a resin temperature of 190 ° C. A composite film was obtained with a draft ratio of 850 while cutting a part in the extrusion direction. This unstretched film was annealed at 115 ° C for 12 hours, then stretched 1.2 times at room temperature, and subsequently stretched 2.0 times at 111 ° C. Both support layers were porous polyethylene, and the intermediate layer was a homogeneous thin film. A layered flat film (thickness 90 μm) was obtained. The thickness of both the innermost layer and the outermost layer of the porous layer was 44 μm, and the porosity was 50 vol%. The homogeneous thin film layer had a thickness of 2.0 μm. In this flat membrane, the oxygen permeation flow rate is 3.0 × 10.^-9cm³·cm^-2 Sec^-1 Pa^-1, Nitrogen permeation flow rate is 1.0 × 10^-⁹cm³·cm^-2 Sec^-1・Pa^-1Met. In addition, the water vapor permeation flow rate is 2.1 x 10^-3g m / (m² It was day). Using this three-layer composite flat membrane, the membrane area is 1 m.²Membrane module was prepared. A decompression pump is connected to the decompression side of this film module to depressurize at 100 Pa, and from the pigment system to the flat film primary side (supply side) from the ink supply pump attached to the inkjet printer (Hewlett Packard "Design Jet 3500CP"). Hewlett Packard black ink was supplied, degassed, degassed ink was supplied to the ink head, and printing was performed on special paper with a width of 54 inches. The dissolved oxygen concentration in the printer ink after degassing was 0.05 ppm. Printing was performed until the ink filled in the inkjet printer ink cartridge was completely used up. The dissolved oxygen concentration in the ink immediately before it was used up was 0.08 ppm. When the number of print omission dots and the total number of print omission dots were observed with a magnifying projector and the print omission frequency was calculated, the print omission frequency was 0.5%, which was constant during the degassing operation.

【0055】

[Example 8] "MK resin MK-2F" manufactured by Dainippon Plastics Co., Ltd. was used as a polymer blend composed of a styrene-based thermoplastic elastomer and polypropylene. This polymer alloy is placed in the intermediate layer, and the structure is such that the intermediate layer is sandwiched from both sides with Tosoh's high-density polyethylene "Nipolon Hard 5110" as the support layer, and the molten resin is co-extruded from the annular die at a resin temperature of 190 ° C. A composite film was obtained with a draft ratio of 850 while cutting a part in the extrusion direction. This unstretched film was annealed at 115 ° C for 12 hr, stretched 1.2 times at room temperature, and then stretched 2.0 times at 111 ° C. The support layers on both sides were porous polyethylene, and the intermediate layer was a homogeneous thin film. A layered flat film (thickness 80 μm) was obtained. The porous layer had a thickness of 39 μm on both sides and a porosity of 50 vol%. The homogeneous thin film layer had a thickness of 2.0 μm. Oxygen permeation flow rate in this flat membrane is 3.5 × 10^-9cm³·cm^-2 Sec^-1 Pa^-1, Nitrogen permeation flow rate is 1.0 × 10^-9cm³·cm^-2 Sec^-1 Pa^-1Met. The water vapor permeation flow rate in this example is 1.55 × 10^-3g m / (m² It was day). The membrane area is 0.5m using this three-layer composite flat membrane.²Membrane module was prepared. A decompression pump is connected to the decompression side of this film module to depressurize at 100 Pa, and from the pigment system to the flat film primary side (supply side) from the ink supply pump attached to the inkjet printer (Hewlett Packard "Design Jet 3500CP"). Hewlett Packard black ink was supplied, degassed, degassed ink was supplied to the ink head, and printing was performed on special paper with a width of 54 inches. The dissolved oxygen concentration in the printer ink after degassing was 0.06 ppm. Printing was performed until the ink filled in the inkjet printer ink cartridge was completely used up. The dissolved oxygen concentration in the ink immediately before it was used up was 0.06 ppm. When the number of print omission dots and the total number of print omission dots were observed with a magnifying projector and the print omission frequency was calculated, the print omission frequency was 0.5%, which was constant during the degassing operation.

【0056】

[Test Example 7] Cholesterin Chloride Cholesterin nonanoate (cholesteric liquid crystal) was used as a chemical solution, and a module was prepared using the flat membranes prepared in Examples 1 to 3 (membrane area 0.5 m).²), Degassing treatment was carried out using this. For the supply and degassing of the chemical solution, the same device as in Test Example 1 is used, the chemical solution is pumped with nitrogen gas (2 atm), supplied to one side of the flat membrane at a flow rate of 0.2 L / min, and the decompressed side of the membrane is 100 Pa. And degassed for 30 minutes. Table 8 shows the dissolved nitrogen concentration before and after degassing and the evaluation results in the liquid crystal encapsulation process.

【0057】

[Table 8]

<img file="JP2000288366A_D0010.tif" />【0058】

[Comparative Example 1] In Example 1, melt shaping was performed under the same conditions except that only a styrene-based thermoplastic elastomer (Clayton G-1657 manufactured by Shell Chemical Co., Ltd., 100% by weight) was used for the intermediate layer. However, the melt viscosity of the styrene-based thermoplastic elastomer was high, and the styrene-based thermoplastic elastomer could not be extruded in the molten state from the extruder, so that a three-layer composite flat film could not be obtained.

[Comparative Example 2] In Example 1, "ENGAGE 8400" manufactured by DuPont-Dow Elastomer Co., Ltd. (density 0.870 g / cm) was used as the intermediate layer.³A three-layered flat membrane was obtained under the same conditions except that only) was used. The oxygen permeation flow rate of this flat membrane is 2 × 10.^-7cm³·cm^-2 Sec^-1 CmHg^-1Met. The thickness of the porous layer and the homogeneous thin film was the same as in Example 1. 2m using this three-layer flat membrane²The membrane module was prepared, and raw water with a dissolved oxygen concentration of 8 ppm was supplied to one side of the flat membrane at a flow rate of 5 L / min., And the decompression side of the membrane was kept at 30 torr and degassed. The dissolved oxygen concentration after degassing was 5 ppm.

【0059】

[Comparative Example 3] A hollow fiber membrane module was prepared by bundling 5,000 polypropylene porous hollow fiber membranes (KPF 190M manufactured by Mitsubishi Rayon Co., Ltd.), and the same method as in Example 1 was applied to the developing solution. Degassing, degassing of semiconductor resist, and degassing of ink for inkjet printers were conducted. The developer contained a surfactant. In either case, the drug solution leaked from the pores of the membrane, and the degassing effect of the membrane was not obtained.

[Comparative Example 4] 200 polytetrafluoroethylene tube membranes (Poaflon manufactured by Sumitomo Electrochemical Co., Ltd .: film thickness 50 μm) are bundled to prepare a membrane module, and a developer is prepared in the same manner as in Test Examples 1, 2 and 5. Degassing of the film, degassing of the semiconductor resist, and degassing of the ink for inkjet printers were conducted. The developer contained a surfactant. In either case, the drug solution leaked from the pores of the membrane, and the degassing effect of the membrane was not obtained.

【0060】

[Comparative Example 5] A three-layer composite flat film was prepared by the same method except that the film thickness of the intermediate layer was set to 20 μm in Example 1. Oxygen permeation flow rate in this flat membrane is 4 × 10^-10cm³·cm^-2 Sec^-1 Pa^-1And the nitrogen permeation flow rate is 1.7 × 10^-10cm³·cm^-2 Sec^-1 Pa^-1Met. Using the above three-layer flat membrane, the membrane area is 2 m.²Membrane module was prepared. The developer was degassed in the same manner as in Test Example 2. In the same manner as in Test Example 2, it was observed with a scanning electron microscope whether or not defects were found in the grooves and lands in the 100 μm × 100 μm region of the developing surface. 100 circular undeveloped parts with a radius of 0.5 μm were observed in this area, and the degassing effect by the film type was not observed.

[Comparative Example 6] Mitsubishi Rayon's three-layer composite hollow fiber membrane "MHF200TL" (porous layer is polyethylene, homogeneous thin film is polyurethane, inner diameter 200 μm, homogeneous thin film thickness 1 μm, porous layer thickness 25 μm for each layer, water vapor permeation flow rate But 7.30 × 10^-1g m / (m²-A hollow fiber membrane module was prepared by bundling 5000 pieces of day)), and isopropyl alcohol was degassed by the same method as in Test Example 3. In this example, the homogeneous thin film was swollen by the solution, and the weight change rate of the hollow fiber membrane was 95%. When an attempt was made to perform the degassing treatment using the homogeneous thin film in this case, the homogeneous thin film was torn and the solution leaked from the porous layer, and degassing could not be performed.

【0061】

[Comparative Example 7] Ink is degassed by the same method except that a silicon tube (inner diameter 300 μm, thickness 100 μm) is used as the hollow film for degassing in Example 7, and the degassed ink is supplied to the ink head. Then, printing was performed on special paper with a width of 54 inches. Printing was performed until the ink filled in the inkjet printer ink cartridge was completely used up. When the number of missing dots and the total number of missing printing dots were observed with a magnifying projector on the printed image immediately after the start of printing and the printing missing frequency was calculated, the printing missing frequency was 0.1%, which was about half that of the filled ink. When the print omission frequency was calculated by the same method at the time of using, the print omission frequency was 5%. When observing the secondary side surface of the degassing tube when about half of the filling ink is used, scum is accumulated, the apparent gas permeability is reduced, and the dissolved gas concentration is the saturation concentration under atmospheric pressure. It was 70% of. This decrease in gas permeability is considered to be the cause of the decrease in the frequency of print omissions.

[Comparative Example 8] A membrane module was prepared by bundling 1200 silicon tubes (inner diameter 300 μm, outer diameter 500 μm, film thickness 100 μm) into a hollow fiber bundle. The same ink as in Example 8 was supplied to this film module, the same printer was operated, and an ink printing test was performed. At the start of printing, the printing omission frequency was 0.2%, but just before printing was performed and the ink was used up, the printing omission frequency was 5%. Scum was deposited on the side surface on the negative pressure side of the membrane housed in this membrane module. At this time, the apparent gas permeability of the membrane decreased, and the dissolved gas concentration was 95% of the saturation concentration under atmospheric pressure. This decrease in gas permeability is considered to be the cause of the decrease in the frequency of print omissions.

【0062】

[Comparative Example 9] In Comparative Example 8, 1200 tetrafluoroethylene tubes (inner diameter 300 μm, outer diameter 500 μm, film thickness 100 μm) were bundled in place of the silicon tube to form a hollow fiber bundle to prepare a membrane module. The same ink as in Example 8 was supplied to this film module, the same printer was operated, and an ink printing test was performed. At the start of printing, the printing omission frequency was 0.2%, but just before printing was performed and the ink was used up, the printing omission frequency was 2%. Scum was deposited on the side surface on the negative pressure side of the membrane housed in this membrane module. At this time, the apparent gas permeability of the membrane decreased, and the dissolved gas concentration was 96% of the saturation concentration under atmospheric pressure. This decrease in gas permeability is considered to be the cause of the decrease in the frequency of print omissions.

[Comparative Example 10] In Test Example 3, an inhomogeneous hollow fiber membrane made of poly (4-methylpentene-1) as a degassing membrane (SEPAREL manufactured by Dainippon Ink and Chemicals Co., Ltd .; glass transition temperature Tg = Degassing of isopropyl alcohol was performed under the same conditions except that 30 ° C) was used. Immediately after the start of the degassing operation, isopropyl alcohol leaked to the secondary side of the membrane and degassing could not be performed.

【0063】

[Comparative Example 11] In Test Example 1, an inhomogeneous hollow fiber membrane made of poly (4-methylpentene-1) (SEPAREL manufactured by Dainippon Ink and Chemicals Co., Ltd.) was used as the degassing membrane. , The semiconductor photoresist solution (chemically amplified positive resist "APEX-E2405" manufactured by SHIPLEY) was degassed under the same conditions. Before immersing the hollow fiber membrane of this example in the photoresist solution, oxygen permeation flow rate / nitrogen permeation flow rate = 1.2, but after immersion, oxygen permeation flow rate / nitrogen permeation flow rate = 0.93, and the weight change rate is It was + 31%. When degassing was performed using this hollow fiber membrane, the photoresist leaked to the secondary side of the membrane immediately after the start of the degassing operation, and degassing could not be performed.

【0064】

[Effect of the invention]

The composite flat membrane of the present invention has a nitrogen permeation flow rate and an oxygen permeation flow rate sufficient to satisfy the degassing achievement level, has a low water vapor permeation flow rate, and leaks when degassing water or a chemical solution. It is an excellent separation membrane without water vapor. In particular, in the case of chemical degassing containing water, it is suitable to use a polymer material composed of a styrene-based thermoplastic elastomer and polyolefin or a fluoroplastic elastomer as a homogeneous thin film, and in the case of chemical degassing, styrene-based thermoplastic Select one of polymer alloy composed of elastomer and polyolefin, copolymer of (2,2 bistrifluoromethyl-4,5-difluoro-1,3 dioxol) and tetrafluoroethylene, and fluoroplastic elastomer. It is useful because the weight change is small even when the chemical immersion test is performed, pinholes are unlikely to occur, and the gas permeability has sufficient durability for practical use. Further, the composite flat membrane of the present invention can be produced at a lower cost and the membrane module price is lower than that of the fluororesin tube membrane conventionally used for degassing chemicals. This can reduce the running cost of the user. In addition, the degassing membrane device using this composite flat membrane can continuously degas the chemical solution to obtain a chemical solution with a low dissolved gas concentration, and the degassing membrane is frequently replaced during the degassing operation. Maintenance is reduced.

[Simple explanation of drawings]

[Figure 1]

It is a perspective view which shows an example of a composite flat membrane.

[Figure 2]

It is a schematic block diagram of the chemical liquid degassing treatment apparatus.

[Fig. 3]

It is a schematic diagram of the resist film after development.

[Explanation of symbols]

1 Porous support layer 2 Homogeneous thin film 3 Chemical supply tank 4 Chemical solution 10 flat membrane module 11 flat membrane 12 Degassing port 13 Decompression pump 18 Degassed chemical supply piping 19 nozzle 20 Nitrogen gas