WO2024241782A1 - 多孔質膜、積層体、及びフィルターエレメント - Google Patents

多孔質膜、積層体、及びフィルターエレメント Download PDF

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WO2024241782A1
WO2024241782A1 PCT/JP2024/015432 JP2024015432W WO2024241782A1 WO 2024241782 A1 WO2024241782 A1 WO 2024241782A1 JP 2024015432 W JP2024015432 W JP 2024015432W WO 2024241782 A1 WO2024241782 A1 WO 2024241782A1
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Prior art keywords
porous membrane
laminate
less
bubble point
formula
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English (en)
French (fr)
Japanese (ja)
Inventor
寛一 片山
篤史 福永
寛之 辻脇
隆昌 橋本
豊 村田
裕太郎 松方
文弘 林
一弥 徳田
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Sumitomo Electric Fine Polymer Inc
Sumitomo Electric Industries Ltd
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Sumitomo Electric Fine Polymer Inc
Sumitomo Electric Industries Ltd
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Priority to JP2025521879A priority Critical patent/JPWO2024241782A1/ja
Priority to CN202480033670.5A priority patent/CN121152673A/zh
Priority to KR1020257038480A priority patent/KR20260012218A/ko
Publication of WO2024241782A1 publication Critical patent/WO2024241782A1/ja
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
    • B01D65/10—Testing of membranes or membrane apparatus; Detecting or repairing leaks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10—Supported membranes; Membrane supports
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/1213—Laminated layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/36—Polytetrafluoroethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/02—Details relating to pores or porosity of the membranes
    • B01D2325/0283—Pore size

Definitions

  • Porous membranes containing polytetrafluoroethylene as a main component have been used as dispersion media and substrate precision filtration filters in the semiconductor-related field and other fields (Patent Documents 1 to 6, Non-Patent Document 1).
  • JP 2021-54892 A International Publication No. 2007/011492 International Publication No. 2020/251909 International Publication No. 2020/251912 JP 2015-226877 A JP 2021-178948 A
  • the porous membrane according to one embodiment of the present disclosure comprises: A porous membrane containing polytetrafluoroethylene as a main component,
  • the porous membrane has a Gurley second and an average bubble point,
  • Gurley second and the average bubble point satisfy the relationship of Equation 1 or Equation 2.
  • G1 ⁇ 0.035 ⁇ P1a Formula 1 G1 ⁇ 0.020 ⁇ P1b Formula 2
  • G1 is the Gurley second of the porous membrane
  • P1a is the average bubble point of the porous membrane
  • the P1a is measured by a bubble point method using a 1a liquid, The surface tension of the 1a liquid is 13 mN/m
  • P1b is the average bubble point of the porous membrane
  • the P1b is measured by a bubble point method using a 1b liquid, The surface tension of the 1b liquid is 21 mN/m.
  • FIG. 1 is a schematic enlarged cross-sectional view of a porous membrane according to one embodiment of the present disclosure.
  • FIG. 2 is a schematic enlarged cross-sectional view of a laminate according to an embodiment of the present disclosure.
  • FIG. 3 is a perspective view of a filter element (1) according to one embodiment of the present disclosure.
  • FIG. 4 is a perspective view of a filter element (2) according to one embodiment of the present disclosure.
  • a porous membrane having a high average bubble point and a laminate including a porous membrane are required as a filter for the precision filtration.
  • the average bubble point is an index showing the difficulty of particles, etc. passing through. The higher the average bubble point, the more difficult it is for particles, etc. to pass through. Therefore, having a high average bubble point means that the capturing performance of fine particles is excellent.
  • porous membranes and laminates comprising a porous membrane if the average bubble point is high, the flow rate of the filtrate through the porous membrane and laminates comprising a porous membrane tends to be low (in other words, the Gurley second of the porous membrane and laminates comprising a porous membrane tends to be high). For this reason, it can be difficult to increase the average bubble point and decrease the Gurley second in porous membranes and laminates comprising a porous membrane. In other words, it can be difficult for porous membranes and laminates comprising a porous membrane to combine excellent fine particle capture performance with excellent permeation efficiency.
  • the present disclosure therefore aims to provide a porous membrane that combines excellent fine particle capture performance and excellent permeation efficiency, a filter element including the porous membrane, a laminate that combines excellent fine particle capture performance and excellent permeation efficiency, and a filter element including the laminate.
  • a porous membrane according to one embodiment of the present disclosure A porous membrane containing polytetrafluoroethylene as a main component, The porous membrane has a Gurley second and an average bubble point, The Gurley second and the average bubble point satisfy the relationship of Formula 1 or Formula 2.
  • G1 ⁇ 0.035 ⁇ P1a Formula 1 G1 ⁇ 0.020 ⁇ P1b Formula 2
  • G1 is the Gurley second of the porous membrane
  • P1a is the average bubble point of the porous membrane
  • the P1a is measured by a bubble point method using a 1a liquid,
  • the surface tension of the first liquid is 13 mN/m
  • P1b is the average bubble point of the porous membrane
  • the P1b is measured by a bubble point method using a 1b liquid,
  • the surface tension of the first liquid is 21 mN/m.
  • the present disclosure provides a porous membrane that combines excellent fine particle capture performance with excellent permeability, and a filter element that includes the porous membrane.
  • P1a may be 450 kPa or more
  • P1b may be 900 kPa or more. This makes it possible to provide a porous membrane that combines better fine particle capture performance and better permeation efficiency, and a filter element that includes the porous membrane.
  • the porous film has crystallites,
  • the crystallite has a length X along the MD direction of the porous membrane and a length Y along the TD direction of the porous membrane,
  • the product XY of the length X and the length Y may be less than 1200 nm2 . This makes it possible to provide a porous membrane having both a superior fine particle capture performance and a superior permeation efficiency, and a filter element including the porous membrane.
  • a filter element according to one embodiment of the present disclosure includes a porous membrane as described in [1] to [3] above.
  • the laminate according to one embodiment of the present disclosure comprises: A laminate comprising one or more of the porous membranes according to the above-mentioned [1] to [3] and a support membrane located on one or both sides of at least one of the porous membranes,
  • the support membrane is porous
  • the support film contains polytetrafluoroethylene as a main component
  • the laminate has a Gurley second and an average bubble point, The Gurley second of the laminate and the average bubble point of the laminate satisfy the relationship of Formula 3 or Formula 4.
  • G2 ⁇ 0.040 ⁇ P2a Formula 3 G2 ⁇ (0.025 ⁇ P2b)-6 Equation 4
  • G2 is the Gurley second of the laminate
  • P2a is the average bubble point of the laminate
  • the P2a is measured by a bubble point method using a 2a liquid,
  • the surface tension of the second liquid is 13 mN/m
  • P2b is the average bubble point of the laminate
  • the P2b is measured by a bubble point method using a 2b liquid,
  • the surface tension of the second liquid is 21 mN/m.
  • the present disclosure provides a laminate that combines excellent fine particle capture performance with excellent permeability efficiency, and a filter element that includes the laminate.
  • the P2a is 510 kPa or more
  • the P2b may be 1000 kPa or more. This makes it possible to provide a laminate having both a better fine particle capture performance and a better permeation efficiency, and a filter element including the laminate.
  • a filter element according to one embodiment of the present disclosure comprises the laminate described in [5] or [6] above.
  • this embodiment is not limited thereto.
  • an expression in the form of "A to B” means the upper and lower limits of a range (i.e., A or more and B or less).
  • a or more and B or less the upper and lower limits of a range
  • FIG. 1 A porous membrane 1 according to an embodiment of the present disclosure will be described with reference to FIG.
  • One embodiment of the present disclosure (hereinafter also referred to as “the present embodiment") is A porous membrane 1 containing polytetrafluoroethylene as a main component, The porous membrane 1 has a Gurley second and an average bubble point.
  • the Gurley second and the average bubble point satisfy the relationship of Formula 1 or Formula 2.
  • G1 ⁇ 0.035 ⁇ P1a Formula 1 G1 ⁇ 0.020 ⁇ P1b Formula 2
  • the porous membrane 1 can suppress the improvement of the Gurley second that accompanies the increase of the average bubble point.
  • the porous membrane 1 can have both excellent fine particle capture performance and excellent permeation efficiency.
  • the average bubble point is measured by a bubble point method, in which a specific liquid is used.
  • the numerical value of the average bubble point varies depending on the surface tension of the specific liquid.
  • Equation 1 is defined for "P1a” measured by the bubble point method using "Liquid 1a”
  • Equation 2 is defined for "P1b” measured by the bubble point method using Liquid 1b.
  • the porous membrane 1 contains polytetrafluoroethylene as a main component.
  • the term "main component” refers to a component with the largest content in terms of mass, for example, a component with a content of 90% by mass or more, preferably 95% by mass or more.
  • the porous membrane 1 may be made of polytetrafluoroethylene.
  • the phrase "the porous membrane 1 is made of polytetrafluoroethylene” means that the porous membrane 1 may contain unavoidable impurities as long as the effect of the present disclosure is achieved.
  • polytetrafluoroethylene is a polymer of tetrafluoroethylene, and is a concept that includes a homopolymer of tetrafluoroethylene and a modified product of the "monopolymer of tetrafluoroethylene".
  • the modified product is a tetrafluoroethylene-hexafluoropropylene copolymer (in other words, a perfluoroethylene propene copolymer.
  • FEP tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer
  • PFA tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer
  • ETFE ethylene-tetrafluoroethylene copolymer
  • the modified product may contain 0.1 mol % or less of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (FVE), or the like.
  • HFP hexafluoropropylene
  • FVE perfluoro(alkyl vinyl ether)
  • the content of polytetrafluoroethylene can be specified based on the absorbance at 4.25 ⁇ m of "-CF 2 -” which indicates tetrafluoroethylene (TFE), the absorbance at 10.18 ⁇ m of "-CH 3 group” which indicates FEP, and the absorbance at 10.07 ⁇ m of "CF 3 O- group” which indicates PFA. It has been confirmed that the same results can be obtained even if different measurement ranges are arbitrarily selected in the same porous membrane 1.
  • the thickness of the porous membrane 1 may be 0.002 mm or more and 0.100 mm or less. When the thickness is less than 0.002 mm, the strength of the porous membrane 1 tends to be insufficient. When the thickness is more than 0.100 mm, the pressure loss during permeation of the filtrate tends to be large.
  • the lower limit of the thickness of the porous membrane 1 may be 0.002 mm or more, 0.005 mm or more, or 0.010 mm or more.
  • the upper limit of the thickness of the porous membrane 1 may be 0.100 mm or less, 0.090 mm or less, or 0.080 mm or less.
  • the thickness of the porous membrane 1 may be 0.005 mm or more and 0.090 mm or less, or 0.010 mm or more and 0.080 mm or less.
  • the thickness of the porous membrane 1 can be determined by the following method. First, a standard digital thickness gauge is used to measure the thickness at one arbitrary location. Next, the same standard digital thickness gauge is used to measure the thickness at nine other arbitrary locations. Next, the average thickness value of the total of 10 locations is calculated, thereby determining the thickness of the porous membrane 1.
  • the porous membrane 1 has a long shape.
  • the density of the porous membrane 1 may be 0.05 g/cm 3 or more and 2.00 g/cm 3 or less. When the density is less than 0.05 g/cm 3 , the strength of the porous membrane 1 tends to be insufficient. When the density is more than 2.00 g/cm 3 , the permeation efficiency of the porous membrane 1 tends to decrease.
  • the lower limit of the density of the porous membrane 1 may be 0.05 g/cm 3 or more, 0.10 g/cm 3 or more, or 0.15 g/cm 3 or more.
  • the upper limit of the density of the porous membrane 1 may be 2.00 g/cm 3 or less, 1.70 g/cm 3 or less, or 1.50 g/cm 3 or less.
  • the density of the porous membrane 1 may be 0.10 g/cm 3 or more and 1.70 g/cm 3 or less, or 0.15 g/cm 3 or more and 1.50 g/cm 3 or less.
  • the density of the porous membrane 1 can be determined by a method conforming to ASTM-D-792. It has been confirmed that similar results can be obtained when a different measurement range is arbitrarily selected for the same porous membrane 1 and the above measurements are performed within that measurement range.
  • the basis weight of the porous membrane 1 may be 0.002 mg/mm 2 or more and 0.100 mg/mm 2 or less. When the basis weight of the porous membrane 1 is less than 0.002 mg/mm 2 , the strength of the porous membrane 1 tends to be insufficient. When the basis weight of the porous membrane 1 is more than 0.100 mg/mm 2 , the permeation efficiency of the porous membrane 1 tends to decrease.
  • the lower limit of the basis weight of the porous membrane 1 may be 0.002 mg/mm 2 or more, 0.003 mg/mm 2 or more, or 0.004 mg/mm 2 or more.
  • the upper limit of the basis weight of the porous membrane 1 may be 0.100 mg/mm 2 or less, 0.080 mg/mm 2 or less, or 0.060 mg/mm 2 or less.
  • the basis weight of the porous membrane 1 may be 0.003 mg/mm 2 or more and 0.080 mg/mm 2 or less, or may be 0.004 mg/mm 2 or more and 0.060 mg/mm 2 or less.
  • the basis weight of the porous membrane 1 can be determined by the following method. First, an evaluation sample is obtained by cutting an arbitrary one portion of the porous membrane 1 into a circle with a diameter of 60.0 mm. Next, the mass of the evaluation sample is determined using an analytical balance "AP224X" (trademark) manufactured by Shimadzu Corporation. Next, the basis weight is obtained by dividing the mass of the evaluation sample by the area of the evaluation sample (in other words, 30.02 ⁇ ). Next, the basis weight is determined by the same method as above for the other nine arbitrary portions. Next, the basis weight of the porous membrane 1 can be determined by calculating the average value of the basis weights of a total of 10 portions.
  • AP224X analytical balance
  • the porous membrane 1 has an average bubble point (P1a and P1b).
  • P1a may be 450 kPa or more. This allows the fibers of the porous membrane 1 to be formed thin and dense, so that the porous membrane 1 can have both a higher average bubble point and a lower Gurley second.
  • the lower limit of P1a may be 450 kPa or more, 470 kPa or more, or 500 kPa or more.
  • the upper limit of P1a may be 900 kPa or less, 890 kPa or less, or 880 kPa or less.
  • P1a may be 470 kPa or more and 890 kPa or less, or 500 kPa or more and 880 kPa or less.
  • P1b may be 900 kPa or more. This allows the fibers of the porous membrane 1 to be formed thin and dense, so that the porous membrane 1 can have both a higher average bubble point and a lower Gurley second.
  • the lower limit of P1b may be 910 kPa or more, or 920 kPa or more.
  • the upper limit of P1b may be 1600 kPa or less, 1500 kPa or less, or 1400 kPa or less.
  • P1b may be 900 kPa or more and 1600 kPa or less, or 910 kPa or more and 1500 kPa or less.
  • P1a is measured by the bubble point method using the 1a liquid, and the surface tension of the 1a liquid is 13 mN/m. More specifically, in the porous membrane 1, P1a is determined by the following method. First, for a dry porous membrane 1, the differential pressure applied to the porous membrane 1 and the air flow rate passing through the porous membrane 1 are measured based on the bubble point method (ASTM F316-86, JIS K3832). Next, in a coordinate system with the differential pressure on the horizontal axis and the air flow rate on the vertical axis, a first curve is obtained that shows the relationship between the differential pressure and the numerical value obtained by dividing the air flow rate by 2.
  • the porous membrane 1 is immersed in "Opteon SF70" (trademark), a hydrofluoroolefin (1a liquid) manufactured by Mitsui-Chemours Fluoroproducts, Inc., for 5 minutes at 25°C, and then removed from the hydrofluoroolefin (1a liquid) to obtain a porous membrane 1 wet with hydrofluoroolefin (1a liquid).
  • the differential pressure applied to the porous membrane 1 and the air flow rate passing through the porous membrane 1 are measured based on the bubble point method.
  • a second curve showing the relationship between the differential pressure and the air flow rate is obtained in a coordinate system with the horizontal axis representing the differential pressure and the vertical axis representing the air flow rate.
  • the differential pressure at the intersection of the first curve and the second curve is specified as the average bubble point P1a.
  • the surface tension of the hydrofluoroolefin (1a liquid) is 13 mN/m.
  • P1b is measured by the bubble point method using the 1b liquid, and the surface tension of the 1b liquid is 21 mN/m. More specifically, in the porous membrane 1, P1b is determined in a manner similar to the measurement method of P1a, except that isopropyl alcohol (1b liquid) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. is used instead of the 1a liquid.
  • the porous membrane 1 has a Gurley second (G1).
  • G1 may be 1 second or more and 100 seconds or less. This allows the flow rate of the filtrate to be increased, so that the permeation efficiency can be increased and the capture performance of the fine particles contained in the filtrate can be improved.
  • the lower limit of G1 may be 1 second or more, 3 seconds or more, or 5 seconds or more.
  • the upper limit of G1 may be 100 seconds or less, 80 seconds or less, or 60 seconds or less.
  • G1 may be 3 seconds or more and 80 seconds or less, or 5 seconds or more and 60 seconds or less.
  • G1 can be determined by the following method. According to JIS P 8117, the time required for 100 ml of air to permeate through an effective membrane area of 6.42 cm2 at a differential pressure of 1.22 kPa is measured. The time is determined as G1.
  • G1 is the Gurley second of the porous membrane 1
  • P1a is the average bubble point of the porous membrane 1
  • the P1a is measured by a bubble point method using a 1a liquid, The surface tension of the 1a liquid is 13 mN/m
  • P1b is the average bubble point of the porous membrane 1
  • the P1b is measured by a bubble point method using a 1b liquid, The surface tension of the 1b liquid is 21 mN/m.
  • the porous membrane 1 can have both a high average bubble point and a low Gurley second, and therefore can have both excellent particle capture performance and excellent permeation efficiency.
  • "0.035” means the slope of the linear function.
  • "0.020” means the slope of the linear function.
  • the mean flow pore size of the porous membrane 1 may be 25 nm or more and 70 nm or less. This allows both high permeation efficiency and high trapping performance of fine particles contained in the filtrate.
  • the lower limit of the mean flow pore size may be 25 nm or more, 26 nm or more, or 27 nm or more.
  • the upper limit of the mean flow pore size may be 70 nm or less, 67 nm or less, or 65 nm or less.
  • the mean flow pore size may be 26 nm or more and 67 nm or less, or 27 nm or more and 65 nm or less.
  • the average flow pore size of the porous membrane 1 can be determined by the following measurement method. That is, first, for a dry porous membrane 1, the differential pressure applied to the porous membrane 1 and the air flow rate passing through the porous membrane 1 are measured based on the bubble point method. Next, in a coordinate system with the differential pressure on the horizontal axis and the air flow rate on the vertical axis, a third curve is obtained showing the relationship between the differential pressure and the numerical value obtained by dividing the air flow rate by 2.
  • the porous membrane 1 is immersed in GALWICK (propylene, 1,1,2,3,3,3-hexafluorofluoride oxide, fourth liquid) manufactured by Porous Materials for 5 minutes at 25°C, and then removed from the GALWICK (fourth liquid) to obtain a porous membrane 1 wet with the GALWICK (fourth liquid).
  • GALWICK propylene, 1,1,2,3,3,3-hexafluorofluoride oxide, fourth liquid
  • the differential pressure applied to the porous membrane 1 and the air flow rate passing through the porous membrane 1 are measured based on the bubble point method.
  • a fourth curve showing the relationship between the differential pressure and the air flow rate is obtained in a coordinate system with the horizontal axis representing the differential pressure and the vertical axis representing the air flow rate.
  • the differential pressure P' at the intersection of the third curve and the fourth curve is specified.
  • the average flow pore size [nm] of the porous membrane 1 is obtained by dividing the product of the constant 2860 and the surface tension of the fourth liquid, 16 mN/m, by the differential pressure P'.
  • a PMI Perm Porometer "CFP-1500A" is used as a pore diameter distribution measuring device.
  • the porous membrane 1 has a crystallite, and the crystallite has a length X along the MD direction of the porous membrane 1 and a length Y along the TD direction of the porous membrane 1.
  • crystallite means a portion of the smallest unit that can be regarded as a single crystal among crystal grains.
  • the upper limit of the length X along the MD direction of the porous membrane 1 may be less than 60 nm. When the length X along the MD direction of the porous membrane 1 is 60 nm or more, the average bubble point tends to be small and the capturing performance of fine particles tends to be easily reduced.
  • the upper limit of the length X along the MD direction of the porous membrane 1 may be less than 59 nm or less than 58 nm.
  • the lower limit of the length X along the MD direction of the porous membrane 1 is not particularly limited, but can be, for example, 5 nm or more, 7 nm or more, or 10 nm or more.
  • the "MD direction" can be rephrased as the long length direction.
  • the "TD direction” can be rephrased as the direction perpendicular to the "MD direction” and the thickness direction of the porous membrane 1.
  • the length X of the porous film 1 along the MD direction can be determined by X-ray diffraction measurement.
  • BL16 of the synchrotron radiation facility SAGA-LS is used for the X-ray diffraction measurement.
  • a double crystal spectrometer using Si (111) diffraction is used to monochromatize the X-ray wavelength to 0.124 nm.
  • the measurement is performed by the transmission method, and a double slit optical system is used with a NaI scintillation counter as a detector.
  • the receiving slits are all 0.5 mm long (diffraction angle measurement direction) and 3 mm wide (perpendicular to the diffraction angle measurement direction).
  • the length X is calculated based on the Scherrer formula (Equation 5 below) with the Scherrer constant being 1.
  • ⁇ 1 means the wavelength of the X-ray and is 0.124 nm.
  • X ⁇ 1/(B1cos ⁇ 1) Equation 5
  • the upper limit of the length Y of the porous membrane 1 along the TD direction may be less than 60 nm. If the length Y of the porous membrane 1 along the TD direction is 60 nm or more, the average bubble point becomes smaller (i.e., the fine particle capture performance becomes lower), and the permeation efficiency tends to be easily reduced.
  • the upper limit of the length Y of the porous membrane 1 along the TD direction may be less than 59 nm, or may be less than 58 nm.
  • the lower limit of the length Y of the porous membrane 1 along the TD direction is not particularly limited, but can be, for example, 5 nm or more, 7 nm or more, or 10 nm or more.
  • the length Y of the porous film 1 along the TD direction can be determined by X-ray diffraction measurement.
  • BL16 of the synchrotron radiation facility SAGA-LS is used for the X-ray diffraction measurement.
  • a double crystal spectrometer using Si (111) diffraction is used to monochromatize the X-ray wavelength to 0.124 nm.
  • the measurement is performed by the transmission method, and a double slit optical system is used with a NaI scintillation counter as a detector.
  • the receiving slits are all 0.5 mm long (in the direction of measuring the diffraction angle) and 3 mm wide (perpendicular to the direction of measuring the diffraction angle).
  • the X-ray diffraction measurement is performed after measuring the "length X of the porous film 1 along the MD direction" and then rotating the porous film 1 by 90° along a virtual plane perpendicular to the film thickness direction of the porous film 1.
  • the length Y is calculated based on the Scherrer formula (the following formula 6) in which the Scherrer constant is 1.
  • ⁇ 2 means the wavelength of the X-ray and is 0.124 nm.
  • Y ⁇ 2/(B2cos ⁇ 2) Equation 6
  • the product XY of the length X and the length Y may be less than 1200 nm2 .
  • the upper limit of the product XY of the length X and the length Y may be less than 1100 nm2 , or may be less than 1000 nm2 .
  • the lower limit of the product XY of the length X and the length Y is not particularly limited, but can be, for example, 30 nm2 or more, 50 nm2 or more, or 100 nm2 or more.
  • the above-mentioned crystallite may be made of polytetrafluoroethylene. This makes it easy for the crystallite density of the porous membrane 1 to be high in crystallinity, and therefore it can have both higher permeability and higher trapping performance of the fine particles contained in the filtrate.
  • "made of polytetrafluoroethylene” is not limited to the embodiment of being made of polytetrafluoroethylene only, but also includes the embodiment of being made of components other than polytetrafluoroethylene (for example, inevitable impurities) as long as the effect of the present disclosure is achieved.
  • the method for producing the porous film according to the present embodiment includes the steps of: 1-1 step of obtaining a kneaded product of polytetrafluoroethylene powder and liquid lubricant; 1-2 step of obtaining a sheet-like molded body by extrusion molding the kneaded product; 1-3 step of obtaining an elongated body by biaxially stretching the molded body; and 1-4 step of obtaining a porous film by heat treatment of the elongated body.
  • the 1-4 step is carried out under the condition of less than 345°C.
  • Step 1-1 is carried out by kneading a polytetrafluoroethylene powder with a liquid lubricant to obtain a kneaded product. More specifically, first, a mixture is obtained by mixing the polytetrafluoroethylene powder with the liquid lubricant. Next, the mixture is compression molded into a block shape using a compression molding machine to obtain the kneaded product.
  • Polytetrafluoroethylene powder refers to a powder consisting of fine particles of polytetrafluoroethylene.
  • Examples of polytetrafluoroethylene powder include "PTFE (polytetrafluoroethylene) fine powder” produced by emulsion polymerization, and "PTFE molding powder” produced by suspension polymerization.
  • the number average molecular weight of polytetrafluoroethylene in the polytetrafluoroethylene powder may be 12 million or more and 50 million or less, from the viewpoint of being able to promote the growth of the fibrous skeleton while preventing excessive expansion of the pore size during stretching and rupture of the porous film.
  • the second heat of fusion in the polytetrafluoroethylene powder may be 10 J/g or more and 25 J/g or less, from the viewpoint of being dependent on the number average molecular weight in the polytetrafluoroethylene powder.
  • the second heat of fusion can be specified by the following method.
  • the polytetrafluoroethylene powder is heated from room temperature to 380°C at a rate of 10°C/min (Pattern 1 (1st Run)), then cooled from 380°C to 100°C at a rate of -1°C/min (Pattern 2), and then heated from 100°C to 380°C at a rate of 10°C/min (Pattern 3 (2nd Run)).
  • the endothermic heat obtained by integrating the 48°C section from the end set temperature of the peak in the range of 300°C to 360°C of the melting curve of Pattern 3 is defined as the second heat of fusion.
  • liquid lubricants various lubricants that have been used in the extrusion method can be used.
  • liquid lubricants include petroleum solvents such as solvent naphtha and white oil, hydrocarbon oils such as undecane, aromatic hydrocarbons such as toluene and xylol, alcohols, ketones, esters, silicone oil, fluorochlorocarbon oil, solutions of polymers such as polyisobutylene and polyisoprene dissolved in these solvents, water or aqueous solutions containing surfactants, etc.
  • solvents such as solvent naphtha and white oil
  • hydrocarbon oils such as undecane
  • aromatic hydrocarbons such as toluene and xylol
  • alcohols ketones
  • esters such as toluene and xylol
  • silicone oil such as toluene and xylol
  • fluorochlorocarbon oil solvents
  • solutions of polymers such as polyisobutylene and polyisoprene
  • the mass parts of the liquid lubricant per 100 mass parts of polytetrafluoroethylene powder may be 10 parts by mass or more and 40 parts by mass or less. If the mass parts of the liquid lubricant are less than 10 parts by mass, extrusion tends to be difficult. If the mass parts of the liquid lubricant are more than 40 parts by mass, compression molding tends to be difficult.
  • additives may be used as materials for the kneaded product.
  • examples of other additives include pigments for coloring, carbon black for improving abrasion resistance, preventing low-temperature flow, and facilitating pore formation, graphite, silica powder, glass powder, glass fiber, inorganic fillers such as silicates and carbonates, metal powder, metal oxide powder, and metal sulfide powder.
  • substances that can be removed or decomposed by heating, extraction, dissolution, etc. such as ammonium chloride, sodium chloride, plastics other than polytetrafluoroethylene, and rubber, may be used in the form of a powder or solution.
  • the 1-2 step is carried out by extruding the kneaded material to obtain a sheet-like molded body. More specifically, the kneaded material is extruded into a sheet at room temperature (for example, 25°C) or higher and 50°C or lower, and at a speed of, for example, 10 mm/min to 30 mm/min to obtain a precursor of the sheet-like molded body. Furthermore, the precursor is rolled with a calendar roll or the like to obtain a sheet-like molded body having an average thickness of 0.250 mm to 0.400 mm. The average thickness can be determined in the same manner as the thickness of the porous membrane 1, except that the measurement is performed on the molded body.
  • the liquid lubricant contained in the molded body may be removed.
  • the liquid lubricant can be removed by heating, extracting, dissolving, or the like, the molded body.
  • the molded body can be rolled with a heated roll at 130°C or higher and 220°C or lower to remove the liquid lubricant from the molded body.
  • liquid lubricants with relatively high boiling points such as silicone oil and fluorochlorocarbon oil, removal by extraction is preferable.
  • Step 1-3 is carried out by biaxially stretching the molded body to obtain a stretched body.
  • biaxial stretching means stretching the sheet-like molded body in the MD direction (in other words, the flow direction of the molded body) and the TD direction perpendicular to the MD direction.
  • the temperature in step 1-3 may be 60°C or higher and 300°C or lower. If the temperature is higher than 300°C, the pore size of the porous membrane tends to become too large (in other words, the average bubble point of the porous membrane tends to become too small). If the temperature is lower than 60°C, the pore size tends to become too small (in other words, the average bubble point of the porous membrane tends to become too large). By adjusting the temperature in step 1-3 to the range of "60°C or higher and 300°C or lower," the average bubble point P1 and the product XY of length X and length Y can be adjusted to the desired range.
  • the stretching ratio in the MD direction may be 1.5 times or more and 20 times or less.
  • the stretching ratio in the MD direction means a value obtained by dividing the average length in the MD direction immediately after stretching in the MD direction by the average length in the MD direction immediately before stretching in the MD direction. If the stretching ratio in the MD direction is less than 1.5 times, the thickness of the porous film may be outside the desired range. If the stretching ratio in the MD direction is more than 20 times, the thickness of the porous film may be outside the desired range.
  • the "average length in the MD direction” means the average value of the length in the MD direction at any 10 points.
  • the stretching ratio in the TD direction may be 1.5 times or more and 100 times or less.
  • the stretching ratio in the TD direction means a value obtained by dividing the average length in the TD direction immediately after stretching in the TD direction by the average length in the TD direction immediately before stretching in the TD direction. If the stretching ratio in the TD direction is less than 1.5 times, the thickness of the porous film may be outside the desired range. If the stretching ratio in the TD direction is more than 100 times, the thickness of the porous film may be outside the desired range.
  • the "average length in the TD direction" means the average value of the length in the TD direction at any 10 points.
  • Step 1-4 is performed by subjecting the stretched body to a heat treatment to obtain a porous membrane.
  • Step 1-4 is performed under conditions of less than 345°C. This allows the porous membrane to satisfy the relationship of formula 1 or formula 2 above. In addition, it is possible to prevent the porous membrane from shrinking over time.
  • step 1-4 by adjusting the heat treatment temperature to a range of "less than 345°C", it is possible to adjust the Gurley second, the average bubble point, and the product XY of length X and length Y to desired ranges.
  • the time for step 1-4 may be 0.1 minutes or more and 20 minutes or less. If the time is less than 0.1 minutes, it tends to be difficult to prevent the porous membrane from shrinking over time. If the time exceeds 20 minutes, the average bubble point of the porous membrane tends to increase excessively. By adjusting the time for step 1-4 within the range of "0.1 minutes or more and 20 minutes or less,” the average bubble point and the product XY of length X and length Y can be adjusted to the desired range.
  • a porous membrane containing polytetrafluoroethylene as a main component, the porous membrane having a Gurley second and an average bubble point, the Gurley second and the average bubble point satisfying the relationship of the above formula 1 or the above formula 2, can be obtained.
  • the filter element 500 according to this embodiment includes the porous membrane 570 according to embodiment 1.
  • the filter element 500 according to this embodiment is not particularly limited as long as it includes the porous membrane 570 according to embodiment 1, but for example, in the filter element 500, the porous membrane 570 may have a pleated structure.
  • the present disclosure makes it possible to provide a filter element with a porous membrane that combines a high average bubble point and a low Gurley second.
  • a filter element 500 is shown that includes a porous membrane 570 having a pleated structure.
  • the porous membrane 570 is sandwiched between two protective materials 520, 540 and folded in pleats, and wrapped around a core 550 that has a number of liquid collection ports 590.
  • An outer peripheral guard 510 is provided on the outside to protect the porous membrane 570.
  • the porous membrane 570 is sealed at both ends of the cylinder by end plates 560a, 560b. The end plates contact the seal parts of the filter housing (not shown) via gaskets 600.
  • the filtered liquid is collected from the liquid collection ports 590 of the core 550 and recovered from the outlet 580.
  • the method for producing the filter element according to this embodiment can be carried out in the same manner as the conventionally known method, except that the porous membrane according to the first embodiment is used.
  • the laminate 10 according to this embodiment will be described with reference to FIG.
  • the laminate 10 according to this embodiment is A laminate 10 comprising one or more porous membranes 1 according to embodiment 1 and a support membrane 2 located on one or both sides of at least one of the porous membranes 1,
  • the support membrane 2 is porous,
  • the support film 2 contains polytetrafluoroethylene as a main component,
  • the laminate 10 has a Gurley second and an average bubble point.
  • the Gurley second of the laminate 10 and the average bubble point of the laminate 10 satisfy the relationship of Formula 3 or Formula 4.
  • G2 ⁇ 0.040 ⁇ P2a Formula 3 G2 ⁇ (0.025 ⁇ P2b)-6 Equation 4
  • the laminate 10 can suppress the improvement of the Gurley second that accompanies the increase of the average bubble point.
  • the porous membrane 1 can have both excellent particle capture performance and excellent permeation efficiency.
  • the average bubble point is measured by a bubble point method, in which a specific liquid is used.
  • the numerical value of the average bubble point varies depending on the surface tension of the specific liquid.
  • Equation 3 relating to "P2a” measured by the bubble point method using "2a liquid”
  • Equation 4 relating to "P2b” measured by the bubble point method using "2b liquid” are defined.
  • the laminate 10 includes one or more porous membranes 1 according to the first embodiment, and a support membrane 2 located on one or both sides of at least one of the porous membranes 1.
  • the support membrane 2 functions as a protective material for the porous membrane 1 according to the first embodiment, thereby improving the capture performance of the laminate 10 and increasing the mechanical strength and lifespan of the laminate 10.
  • the thickness of the laminate 10 may be 0.010 mm or more and 0.200 mm or less. If the thickness is less than 0.010 mm, the strength of the laminate 10 tends to be insufficient. If the thickness is more than 0.200 mm, the pressure loss during permeation of the filtrate tends to be large.
  • the lower limit of the thickness of the laminate 10 may be 0.010 mm or more, 0.013 mm or more, or 0.015 mm or more.
  • the upper limit of the thickness of the laminate 10 may be 0.200 mm or less, 0.150 mm or less, or 0.100 mm or less.
  • the thickness of the laminate 10 may be 0.013 mm or more and 0.150 mm or less, or 0.015 mm or more and 0.100 mm or less.
  • the thickness of the laminate 10 can be determined in a manner similar to the method for measuring the thickness of the porous membrane 1, except that the measurement is performed on the "laminate 10." It has been confirmed that similar results can be obtained when a different measurement range is arbitrarily selected for the same laminate 10 and the above measurement is performed in that measurement range.
  • the density of the laminate 10 may be 0.10 g/cm 3 or more and 2.00 g/cm 3 or less. When the density is less than 0.10 g/cm 3 , the strength of the laminate 10 tends to be insufficient. When the density is more than 2.00 g/cm 3 , the transmission efficiency of the laminate 10 tends to decrease.
  • the lower limit of the density of the laminate 10 may be 0.10 g/cm 3 or more, 0.13 g/cm 3 or more, or 0.15 g/cm 3 or more.
  • the upper limit of the density of the laminate 10 may be 2.00 g/cm 3 or less, 1.70 g/cm 3 or less, or 1.50 g/cm 3 or less.
  • the density of the laminate 10 may be 0.13 g/cm 3 or more and 1.70 g/cm 3 or less, or 0.15 g/cm 3 or more and 1.50 g/cm 3 or less.
  • the density of the laminate 10 can be determined by a method similar to the "Method of measuring the density of the porous membrane 1" described in embodiment 1, except that the measurement is performed on the "laminated body 10." It has been confirmed that similar results can be obtained by arbitrarily selecting different measurement ranges in the same laminate 10 and performing the above measurements in those measurement ranges.
  • the basis weight of the laminate 10 may be 0.005 mg/mm 2 or more and 0.100 mg/mm 2 or less. When the basis weight of the laminate 10 is less than 0.005 mg/mm 2 , the strength of the laminate 10 tends to be insufficient. When the basis weight of the laminate 10 is more than 0.100 mg/mm 2 , the permeability efficiency of the laminate 10 tends to decrease.
  • the lower limit of the basis weight of the laminate 10 may be 0.005 mg/mm 2 or more, 0.007 mg/mm 2 or more, or 0.008 mg/mm 2 or more.
  • the upper limit of the basis weight of the laminate 10 may be 0.100 mg/mm 2 or less, 0.080 mg/mm 2 or less, or 0.060 mg/mm 2 or less.
  • the basis weight of the laminate 10 may be 0.007 mg/mm 2 or more and 0.080 mg/mm 2 or less, or may be 0.008 mg/mm 2 or more and 0.060 mg/mm 2 or less.
  • the basis weight of the laminate 10 can be determined by a method similar to the "method of measuring the basis weight of the porous membrane 1" described in embodiment 1, except that the measurement is performed on the "laminate 10." It has been confirmed that similar results can be obtained by arbitrarily selecting different measurement ranges in the same laminate 10 and performing the above measurements in those measurement ranges.
  • the laminate 10 has an average bubble point (P2a and P2b).
  • P2a may be 510 kPa or more. This allows the laminate to have thin fibers and high density, so that the laminate 10 can have both a higher average bubble point and a lower Gurley second.
  • the lower limit of P2a may be 510 kPa or more, 520 kPa or more, or 530 kPa or more.
  • the upper limit of P2a may be 1000 kPa or less, 990 kPa or less, or 980 kPa or less.
  • P2a may be 510 kPa or more and 1000 kPa or less, or 520 kPa or more and 990 kPa or less.
  • P2b may be 1000 kPa or more. This allows the fibers of the laminate 10 to be formed thin and dense, so that the laminate 10 can have both a higher average bubble point and a lower Gurley second.
  • the lower limit of P2b may be 1020 kPa or more, or 1040 kPa or more.
  • the upper limit of P2b may be 1600 kPa or less, 1500 kPa or less, or 1465 kPa or less.
  • P2b may be 1000 kPa or more and 1600 kPa or less, or 1020 kPa or more and 1500 kPa or less.
  • P2a is measured by the bubble point method using the 2a liquid, and the surface tension of the 2a liquid is 13 mN/m. More specifically, in the laminate 10, P2a is determined in a manner similar to the measurement method of P1a, except that the measurement is performed on the "laminate" and the name of the liquid “1a liquid” is replaced with "2a liquid”.
  • P2b is measured by the bubble point method using the second b liquid, and the surface tension of the second b liquid is 21 mN/m. More specifically, in the porous film 1, P2b is determined in a manner similar to the measurement method for P1a, except that isopropyl alcohol (second b liquid) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. is used instead of the first a liquid.
  • isopropyl alcohol (second b liquid) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. is used instead of the first a liquid.
  • the laminate 10 has a Gurley second (G2).
  • G2 may be 1 second or more and 100 seconds or less. This allows the flow rate of the filtrate to be increased, so that the permeation efficiency can be increased and the capture performance of fine particles contained in the filtrate can be improved.
  • the lower limit of G2 may be 1 second or more, 3 seconds or more, or 5 seconds or more.
  • the upper limit of G2 may be 100 seconds or less, 80 seconds or less, or 70 seconds or less.
  • G2 may be 3 seconds or more and 80 seconds or less, or 5 seconds or more and 70 seconds or less.
  • G2 is determined by the following method. Except for the fact that the measurement is performed on the “laminate", it can be determined by the same method as the "Method of measuring G1 of the porous membrane 1" in embodiment 1.
  • G2 is the Gurley second of the laminate 10
  • P2a is the average bubble point of the laminate 10
  • the P2a is measured by a bubble point method using a 2a liquid, The surface tension of the 2a liquid is 13 mN/m
  • P2b is the average bubble point of the laminate 10
  • the P2b is measured by a bubble point method using a second b liquid, The surface tension of the second liquid is 21 mN/m.
  • the laminate 10 can have both a high average bubble point and a low Gurley second, and therefore can have both excellent fine particle capture performance and excellent permeation efficiency.
  • "0.040” means the slope of the linear function.
  • "0.025” means the slope of the linear function, and "-6" means the intercept of the linear function.
  • the mean flow pore size of the laminate 10 may be 25 nm or more and 100 nm or less. This allows for both higher permeation efficiency and higher trapping performance of fine particles contained in the filtrate.
  • the lower limit of the mean flow pore size may be 25 nm or more, 26 nm or more, or 27 nm or more.
  • the upper limit of the mean flow pore size may be 100 nm or less, 60 nm or less, or 55 nm or less.
  • the mean flow pore size may be 26 nm or more and 60 nm or less, or 27 nm or more and 55 nm or less.
  • the mean flow pore size of the laminate 10 can be determined in a manner similar to the "Method of measuring the mean flow pore size of the porous membrane 1" in embodiment 1, except that the measurement is performed on the "laminated body 10.”
  • the support membrane 2 is porous.
  • porous means that the support membrane 2 has a fibrous skeleton in which pores are connected in a three-dimensional network.
  • the support membrane 2 has a larger pore size than the porous membrane, and does not necessarily inhibit the permeation efficiency.
  • the support membrane 2 is porous can be determined by observing the surface and any cross section of the support membrane 2 using a scanning electron microscope.
  • the thickness of the support film 2 may be 0.002 mm or more and 0.050 mm or less. If the thickness of the support film 2 is less than 0.002 mm, the function of the porous film 1 as a protective material tends to be difficult to exert, and the mechanical strength of the laminate 10 and the life of the laminate 10 tend to be difficult to increase. If the thickness of the support film 2 exceeds 0.050 mm, the porous film 1 tends to be difficult to achieve both the capture performance of the laminate 10 and the permeation efficiency of the laminate 10. The lower limit of the thickness may be 0.002 mm or more, 0.004 mm or more, or 0.006 mm or more.
  • the upper limit of the thickness may be 0.050 mm or less, 0.045 mm or less, or 0.040 mm or less.
  • the thickness may be 0.004 mm or more and 0.045 mm or less, or 0.006 mm or more and 0.040 mm or less.
  • the thickness may be 0.004 mm or more and 0.045 mm or less, or 0.006 mm or more and 0.040 mm or less.
  • the thickness of the support membrane 2 can be determined in a manner similar to the measurement method for the "thickness of the porous membrane 1" described in embodiment 1, except that the measurement is performed on the support membrane 2. It has been confirmed that similar results can be obtained when a different measurement range is arbitrarily selected for the same support membrane 2 and the above measurement is performed in that measurement range.
  • the density of the support film 2 may be 0.10 g/cm 3 or more and 2.00 g/cm 3 or less. When the density is less than 0.10 g/cm 3 , the strength of the laminate 10 tends to be insufficient. When the density is more than 2.00 g/cm 3 , the permeability efficiency of the laminate 10 tends to decrease.
  • the lower limit of the density of the support film 2 may be 0.10 g/cm 3 or more, 0.13 g/cm 3 or more, or 0.15 g/cm 3 or more.
  • the upper limit of the density of the support film 2 may be 2.00 g/cm 3 or less, 1.70 g/cm 3 or less, or 1.50 g/cm 3 or less.
  • the density of the support film 2 may be 0.13 g/cm 3 or more and 1.70 g/cm 3 or less, or 0.15 g/cm 3 or more and 1.50 g/cm 3 or less.
  • the density of the support membrane 2 can be determined by a method similar to that for measuring the density of the porous membrane 1, except that the measurement is performed on the "support membrane 2." It has been confirmed that similar results can be obtained by arbitrarily selecting a different measurement range for the same support membrane 2 and performing the above measurement in that measurement range.
  • the basis weight of the support film 2 may be 0.005 mg/mm 2 or more and 0.100 mg/mm 2 or less. When the basis weight of the support film 2 is less than 0.005 mg/mm 2 , the strength of the laminate 10 tends to be insufficient. When the basis weight of the support film 2 is more than 0.100 mg/mm 2 , the permeability efficiency of the laminate 10 tends to decrease.
  • the lower limit of the basis weight of the support film 2 may be 0.005 mg/mm 2 or more, 0.006 mg/mm 2 or more, or 0.007 mg/mm 2 or more.
  • the upper limit of the basis weight of the support film 2 may be 0.100 mg/mm 2 or less, 0.080 mg/mm 2 or less, or 0.060 mg/mm 2 or less.
  • the basis weight of the support film 2 may be 0.006 mg/mm 2 or more and 0.080 mg/mm 2 or less, or may be 0.007 mg/mm 2 or more and 0.060 mg/mm 2 or less.
  • the basis weight of the support membrane 2 can be determined by the following method. Except for the fact that the measurement is performed on the "support membrane 2", it can be determined by the same method as the method for measuring the basis weight of the porous membrane 1. It has been confirmed that similar results can be obtained when a different measurement range is arbitrarily selected for the same support membrane 2 and the above measurement is performed in that measurement range.
  • the average bubble point P3a of the support film 2 may be 5 kPa or more and 400 kPa or less, or the average bubble point P3b of the support film 2 may be 5 kPa or more and 800 kPa or less. This allows the fibers of the support film 2 to be formed thin and dense, so that the laminate 10 can have both a higher average bubble point and a lower Gurley second.
  • the average bubble point is measured by a bubble point method, in which a specific liquid is used.
  • the numerical value of the average bubble point varies depending on the surface tension of the specific liquid.
  • "P3a” is measured by a bubble point method using a "third a liquid” described below
  • "P3b” is measured by a bubble point method using a "third b liquid” described below.
  • the average bubble point P3a of the support film 2 may be 5 kPa or more and 400 kPa or less. This allows the fibers of the support film 2 to be formed thin and dense, so that the laminate 10 can have both a higher average bubble point and a lower Gurley second.
  • the lower limit of P3a may be 5 kPa or more, 7 kPa or more, or 10 kPa or more.
  • the upper limit of P3a may be 400 kPa or less, 350 kPa or less, or 300 kPa or less.
  • P3a may be 7 kPa or more and 350 kPa or less, or 10 kPa or more and 300 kPa or less.
  • the average bubble point P3b of the support film 2 may be 5 kPa or more and 800 kPa or less. This allows the fibers of the support film 2 to be formed thin and dense, so that the laminate 10 can have both a higher average bubble point and a lower Gurley second.
  • the lower limit of P3b may be 5 kPa or more, 7 kPa or more, or 10 kPa or more.
  • the upper limit of P3b may be 800 kPa or less, 700 kPa or less, or 600 kPa or less.
  • P3b may be 7 kPa or more and 700 kPa or less, or 10 kPa or more and 600 kPa or less.
  • P3a is measured by the bubble point method using the 3a liquid, and the surface tension of the 3a liquid is 13 mN/m. More specifically, in the support film 2, P3a is determined in a manner similar to the measurement method of P1a, except that the measurement is performed on the "support film 2" and the name of the liquid “1a liquid” is replaced with "3a liquid”.
  • P3b is measured by the bubble point method using the 3b liquid, and the surface tension of the 3b liquid is 21 mN/m. More specifically, in the support film 2, P3b is determined in a manner similar to the measurement method of P1a, except that the measurement is performed on the "support film 2" and isopropyl alcohol (3b liquid) manufactured by Fujifilm Wako Pure Chemical Industries is used instead of the 1a liquid.
  • the support membrane 2 has a Gurley second (G3).
  • G3 may be 0.5 seconds or more and 60 seconds or less. This allows the flow rate of the filtrate to be increased, so that the permeation efficiency can be increased and the capture performance of fine particles contained in the filtrate can be improved.
  • the lower limit of G3 may be 0.5 seconds or more, 0.7 seconds or more, or 1.0 seconds or more.
  • the upper limit of G3 may be 60 seconds or less, 50 seconds or less, or 40 seconds or less.
  • G3 may be 0.7 seconds or more and 50 seconds or less, or 1.0 seconds or more and 40 seconds or less.
  • G3 is determined by the following method. Except for the fact that the measurement is performed on the "support membrane 2", it can be determined by the same method as the "Method of measuring G1 of the porous membrane 1" in embodiment 1.
  • the mean flow pore size of the support membrane 2 may be 45 nm or more and 600 nm or less. This allows the laminate 10 to have both higher permeation efficiency and higher trapping performance of fine particles contained in the filtrate.
  • the lower limit of the mean flow pore size may be 45 nm or more, 50 nm or more, or 55 nm or more.
  • the upper limit of the mean flow pore size may be 600 nm or less, 550 nm or less, or 500 nm or less.
  • the mean flow pore size may be 50 nm or more and 550 nm or less, or 55 nm or more and 500 nm or less.
  • the mean flow pore size of the support membrane 2 can be determined by the following measurement method. Except for the fact that the measurement is performed on the "support membrane 2", it can be determined by the same method as the "Method of measuring the mean flow pore size of the porous membrane 1" in embodiment 1.
  • the support film 2 contains polytetrafluoroethylene as a main component. This can improve the heat resistance and chemical stability of the support film 2.
  • the "main component” refers to the component with the largest content in terms of mass, for example, a component with a content of 90 mass% or more, preferably 95 mass% or more.
  • the support film 2 may be made of polytetrafluoroethylene.
  • the phrase "the support film 2 is made of polytetrafluoroethylene” means that the support film 2 may contain inevitable impurities as long as the effects of the present disclosure are achieved.
  • the polytetrafluoroethylene content in the support membrane 2 can be determined by a method similar to the measurement method for "polytetrafluoroethylene content in the porous membrane 1" described in embodiment 1, except that the measurement is performed on the support membrane 2. It has been confirmed that similar results can be obtained by arbitrarily selecting a different measurement range in the same support membrane 2 and performing the above measurement in that measurement range.
  • the method for producing the laminate includes a step 2-1 of preparing the porous membrane according to embodiment 1 and a support membrane, and a step 2-2 of laminating the porous membrane on the support membrane.
  • the step 2-1 includes a step 2-1-a of preparing the porous membrane and a step 2-1-b of preparing the support membrane.
  • Step 2-1-a is carried out by preparing a porous membrane.
  • the porous membrane 1 can be prepared by the method described in the first embodiment.
  • Step 2-1-b is carried out by preparing a support film.
  • the support film can be prepared by a conventionally known method.
  • Step 2-2 is carried out by laminating a porous membrane on one or both sides of a support membrane.
  • a method of laminating a porous membrane on one or both sides of a support membrane includes a method of pressing the support membrane and the porous membrane together.
  • the method of bonding the support film and the porous film is, for example, to first obtain a laminate precursor by overlapping the support film and the porous film. Next, the laminate precursor is pressed from above and below with flat plates, or the laminate precursor is sandwiched from above and below with rotating rollers and sent out.
  • the method of bonding the support film and the porous film is performed by bonding them with a pressure of 100 kgf to 700 kgf. If the pressure is less than 100 kgf, the adhesive strength between the support film and the porous film tends to be insufficient. If the pressure is more than 700 kgf, the pores in the support film and the porous film tend to be crushed, and the permeation efficiency tends to decrease.
  • a laminate 10 can be obtained that includes one or more porous membranes according to embodiment 1 and a support membrane 2 located on one or both sides of at least one of the porous membranes, the support membrane being porous, the support membrane 2 containing polytetrafluoroethylene as a main component, the laminate 10 having a Gurley second and an average bubble point, and the Gurley second of the laminate and the average bubble point of the laminate satisfy the relationship of formula 3 or formula 4 above.
  • the filter element 500 according to this embodiment includes the laminate 670 according to embodiment 3.
  • the filter element 500 according to this embodiment is not particularly limited as long as it includes the laminate 670 according to embodiment 3, but for example, in the filter element 500, the laminate 670 may have a pleated structure.
  • the present disclosure makes it possible to provide a filter element having a laminate that combines a high average bubble point and a low Gurley second.
  • a filter element 500 is shown that includes a laminate 670 having a pleated structure.
  • the structure of the filter element 500 in FIG. 4 is the same as the structure of the filter element 500 in FIG. 3, except that the porous membrane 570 is replaced with the laminate 670.
  • ⁇ Production method of filter element (2)> The method for producing a filter element according to this embodiment can be carried out in the same manner as a conventionally known method, except that the laminate according to the third embodiment is used.
  • Example 1 ⁇ Production of porous membrane>
  • the porous membranes according to Samples 1-1 to 1-8 and Samples 1-101 to 1-105 were produced as follows.
  • a mixture was obtained by mixing "PTFE Fine Powder A (second heat of fusion 15.8 J/g, molecular weight about 28 million)" which is a polytetrafluoroethylene powder, and "Supersol FP-25” (trademark) which is a solvent naphtha (liquid lubricant) manufactured by Idemitsu Oil Co., Ltd., in the parts by mass shown in Table 1.
  • the mixture was compression molded into a block shape using a compression molding machine, to obtain a kneaded product.
  • Step 1-2> The kneaded material was extruded into a sheet under the conditions shown in Table 1 to obtain a precursor of a sheet-like molded product. Next, the precursor was rolled with a calendar roll to obtain a sheet-like molded product having an average thickness as shown in Table 1.
  • the porous membranes according to samples 1-1 to 1-8 correspond to examples.
  • the porous membranes according to samples 1-101 to 1-105 correspond to comparative examples.
  • the porous membranes according to samples 1-1 to 1-8, which satisfy the relationship of the above formula 1 or the above formula 2 have a particularly excellent "particle capture performance" compared to the porous membranes according to samples 1-101 to 1-105, which do not satisfy the relationship of the above formula 1 and the above formula 2.
  • porous membranes according to samples 1-1 to 1-8 which satisfy the relationship of the above formula 1 or the above formula 2, have a particularly excellent permeation efficiency compared to the porous membranes according to samples 1-101 to 1-103, which do not satisfy the relationship of the above formula 1 and the above formula 2. That is, the porous membranes of samples 1-1 to 1-8, which satisfy the relationship of formula 1 or formula 2, can exhibit exceptionally excellent effects of combining excellent "particle capture performance" and excellent permeation efficiency, compared to the porous membranes of samples 1-101 to 1-105, which do not satisfy the relationship of formula 1 or formula 2.
  • porous membranes of samples 1-1 to 1-8 can exhibit the exceptional effect of combining excellent "particle capture performance" with excellent permeability efficiency.
  • Example 2 ⁇ Production of laminate>
  • laminates according to Samples 2-1 to 2-5 and 2-101 to 2-105 were produced in the following manner.
  • Step 2-1-a> A porous membrane was prepared for each sample as follows. First, a polytetrafluoroethylene powder, "PTFE Fine Powder A (second heat of fusion 15.8 J/g, molecular weight approximately 28 million)" was prepared. “ and "Supersol FP-25” (trademark), a solvent naphtha (liquid lubricant) manufactured by Idemitsu Oil Co., Ltd., in the parts by mass shown in Table 4 were mixed to obtain a mixture. The mixture was compression molded into a block shape using a compression molding machine to obtain a kneaded product.
  • PTFE Fine Powder A second heat of fusion 15.8 J/g, molecular weight approximately 28 million
  • Supersol FP-25 trademark
  • solvent naphtha liquid lubricant manufactured by Idemitsu Oil Co., Ltd.
  • the above kneaded material was extruded into a sheet under the conditions shown in Table 4 to obtain a precursor of a sheet-shaped molded product.
  • the precursor was rolled with a calendar roll to obtain a sheet-shaped molded product having an average thickness as shown in Table 4.
  • the molded body was biaxially stretched under the conditions shown in Table 4 to obtain a stretched body.
  • the stretched body was subjected to heat treatment under the conditions shown in Table 4 to obtain a porous film.
  • PTFE fine powder B second heat of fusion 26.0 J/g, molecular weight approximately 5 million
  • Supersol FP-25 trademark
  • solvent naphtha liquid lubricant manufactured by Idemitsu Oil Co., Ltd.
  • the above kneaded material was extruded into a sheet under the conditions shown in Table 5 to obtain a precursor of a sheet-shaped molded product.
  • the precursor was rolled with a calendar roll to obtain a sheet-shaped molded product having an average thickness as shown in Table 5.
  • the molded body was biaxially stretched under the conditions shown in Table 5 to obtain a stretched body.
  • the stretched body was subjected to heat treatment under the conditions shown in Table 5 to obtain a porous support film.
  • porous support membranes were prepared for samples 2-1 to 2-5 and samples 2-101 to 2-105.
  • Step 2-2> The support membrane and the porous membrane were laminated in the order of support membrane-porous membrane-support membrane under the conditions shown in Table 6 to obtain a laminate.
  • the laminates according to samples 2-1 to 2-5 correspond to examples.
  • the laminates according to samples 2-101 to 2-105 correspond to comparative examples.
  • the laminates according to samples 2-1 to 2-5, which satisfy the relationship of formula 1 or 2 and the relationship of formula 3 or 4 have exceptionally superior "particle capture performance" compared to the laminates according to samples 2-101, 2-102, 2-103, and 2-104, which do not satisfy at least one of the relationships of formula 1 or 2 and formula 3 or 4.
  • the laminates according to samples 2-1 to 2-5 which satisfy the relationship of formula 1 or 2 and formula 3 or 4 have exceptionally superior transmission efficiency compared to the laminates according to samples 2-102 and 2-105, which do not satisfy at least one of the relationships of formula 1 or 2 and formula 3 or 4. That is, the laminates of samples 2-1 to 2-6, which satisfy the relationship of formula 1 or 2 and the relationship of formula 3 or 4, can exhibit an exceptionally excellent effect of combining excellent "particle capture performance" and excellent permeation efficiency, compared to the laminates of samples 2-101 to 2-105, which do not satisfy at least any one of the relationships of formula 1 or 2 and formula 3 or 4.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
PCT/JP2024/015432 2023-05-22 2024-04-18 多孔質膜、積層体、及びフィルターエレメント Ceased WO2024241782A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11501961A (ja) * 1995-03-10 1999-02-16 ダブリュ．エル．ゴア アンド アソシエイツ，インコーポレイティド 多孔質ｐｔｆｅフィルムとその製造方法
JP2003138047A (ja) * 2001-10-31 2003-05-14 Umei Taikako Kofun Yugenkoshi 非対称性多孔質ポリテトラフルオロエチレン膜とその製造方法
JP2009501632A (ja) * 2005-07-18 2009-01-22 ゴア エンタープライズ ホールディングス，インコーポレイティド 多孔質ｐｔｆｅ材料及びそれらから製造される物品
JP2015226877A (ja) * 2014-05-30 2015-12-17 住友電工ファインポリマー株式会社 多孔質フィルタ

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES3013251T3 (en) 2019-06-13 2025-04-11 Gore & Ass Lightweight expanded polytetrafluoroethylene membranes having high intrinsic strength and optical transparency
JP7699062B2 (ja) 2019-06-13 2025-06-26 ダブリュ．エル．ゴア アンド アソシエイツ，インコーポレイティド 優れた剛性を有する高配向延伸ポリテトラフルオロエチレン
JP7316893B2 (ja) 2019-09-27 2023-07-28 三井・ケマーズ フロロプロダクツ株式会社 高強度小孔径のポリテトラフルオロエチレン多孔膜
JP7606882B2 (ja) 2020-05-08 2024-12-26 三井・ケマーズ フロロプロダクツ株式会社 高強度小孔径のポリテトラフルオロエチレン及び／または変性ポリテトラフルオロエチレンからなる多孔膜

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11501961A (ja) * 1995-03-10 1999-02-16 ダブリュ．エル．ゴア アンド アソシエイツ，インコーポレイティド 多孔質ｐｔｆｅフィルムとその製造方法
JP2003138047A (ja) * 2001-10-31 2003-05-14 Umei Taikako Kofun Yugenkoshi 非対称性多孔質ポリテトラフルオロエチレン膜とその製造方法
JP2009501632A (ja) * 2005-07-18 2009-01-22 ゴア エンタープライズ ホールディングス，インコーポレイティド 多孔質ｐｔｆｅ材料及びそれらから製造される物品
JP2015226877A (ja) * 2014-05-30 2015-12-17 住友電工ファインポリマー株式会社 多孔質フィルタ

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