WO2022210316A1 - 半透膜支持体及び半透膜支持体の製造方法 - Google Patents
半透膜支持体及び半透膜支持体の製造方法 Download PDFInfo
- Publication number
- WO2022210316A1 WO2022210316A1 PCT/JP2022/014217 JP2022014217W WO2022210316A1 WO 2022210316 A1 WO2022210316 A1 WO 2022210316A1 JP 2022014217 W JP2022014217 W JP 2022014217W WO 2022210316 A1 WO2022210316 A1 WO 2022210316A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- semipermeable membrane
- membrane support
- fiber
- less
- fibers
- Prior art date
Links
- 239000012528 membrane Substances 0.000 title claims abstract description 556
- 238000000034 method Methods 0.000 title claims description 34
- 238000004519 manufacturing process Methods 0.000 title claims description 21
- 239000000835 fiber Substances 0.000 claims abstract description 307
- 229920002994 synthetic fiber Polymers 0.000 claims abstract description 124
- 239000012209 synthetic fiber Substances 0.000 claims abstract description 124
- 239000011230 binding agent Substances 0.000 claims abstract description 69
- 239000004745 nonwoven fabric Substances 0.000 claims abstract description 29
- 238000012360 testing method Methods 0.000 claims abstract description 14
- 230000003746 surface roughness Effects 0.000 claims abstract description 11
- 238000010828 elution Methods 0.000 claims description 45
- 239000006185 dispersion Substances 0.000 claims description 27
- FAWGZAFXDJGWBB-UHFFFAOYSA-N antimony(3+) Chemical compound [Sb+3] FAWGZAFXDJGWBB-UHFFFAOYSA-N 0.000 claims description 7
- 230000004083 survival effect Effects 0.000 claims description 7
- 239000011248 coating agent Substances 0.000 abstract description 23
- 238000000576 coating method Methods 0.000 abstract description 23
- 150000003839 salts Chemical class 0.000 abstract description 21
- 230000000903 blocking effect Effects 0.000 abstract description 14
- 229920000139 polyethylene terephthalate Polymers 0.000 description 39
- 239000005020 polyethylene terephthalate Substances 0.000 description 39
- 230000007547 defect Effects 0.000 description 35
- 229920000728 polyester Polymers 0.000 description 29
- 239000000243 solution Substances 0.000 description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 28
- 238000005259 measurement Methods 0.000 description 25
- 230000015572 biosynthetic process Effects 0.000 description 24
- -1 for example Chemical class 0.000 description 24
- 230000000052 comparative effect Effects 0.000 description 22
- 238000000926 separation method Methods 0.000 description 22
- 229910052751 metal Inorganic materials 0.000 description 19
- 239000002184 metal Substances 0.000 description 19
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 14
- 230000007423 decrease Effects 0.000 description 14
- 238000002844 melting Methods 0.000 description 14
- 238000012545 processing Methods 0.000 description 14
- 239000011593 sulfur Substances 0.000 description 14
- 229910052717 sulfur Inorganic materials 0.000 description 14
- 239000007864 aqueous solution Substances 0.000 description 13
- 239000010410 layer Substances 0.000 description 13
- 229920002492 poly(sulfone) Polymers 0.000 description 13
- 239000002131 composite material Substances 0.000 description 12
- 238000001035 drying Methods 0.000 description 12
- 238000013507 mapping Methods 0.000 description 12
- 230000008018 melting Effects 0.000 description 12
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 11
- 229920005989 resin Polymers 0.000 description 11
- 239000011347 resin Substances 0.000 description 11
- 239000002002 slurry Substances 0.000 description 11
- 229910021642 ultra pure water Inorganic materials 0.000 description 11
- 239000012498 ultrapure water Substances 0.000 description 11
- 238000003490 calendering Methods 0.000 description 10
- 238000011156 evaluation Methods 0.000 description 10
- 230000035699 permeability Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
- 238000001514 detection method Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 239000012466 permeate Substances 0.000 description 8
- 238000004458 analytical method Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000007731 hot pressing Methods 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- 238000003825 pressing Methods 0.000 description 7
- VZSRBBMJRBPUNF-UHFFFAOYSA-N 2-(2,3-dihydro-1H-inden-2-ylamino)-N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]pyrimidine-5-carboxamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C(=O)NCCC(N1CC2=C(CC1)NN=N2)=O VZSRBBMJRBPUNF-UHFFFAOYSA-N 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 6
- 239000002390 adhesive tape Substances 0.000 description 4
- ADCOVFLJGNWWNZ-UHFFFAOYSA-N antimony trioxide Chemical compound O=[Sb]O[Sb]=O ADCOVFLJGNWWNZ-UHFFFAOYSA-N 0.000 description 4
- 239000011247 coating layer Substances 0.000 description 4
- 238000010030 laminating Methods 0.000 description 4
- 239000002346 layers by function Substances 0.000 description 4
- 238000005457 optimization Methods 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- 238000011002 quantification Methods 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- 239000002344 surface layer Substances 0.000 description 4
- QPILHXCDZYWYLQ-UHFFFAOYSA-N 2-nonyl-1,3-dioxolane Chemical compound CCCCCCCCCC1OCCO1 QPILHXCDZYWYLQ-UHFFFAOYSA-N 0.000 description 3
- 101000851593 Homo sapiens Separin Proteins 0.000 description 3
- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- 102100036750 Separin Human genes 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 3
- 238000004873 anchoring Methods 0.000 description 3
- 229940058905 antimony compound for treatment of leishmaniasis and trypanosomiasis Drugs 0.000 description 3
- 150000001463 antimony compounds Chemical class 0.000 description 3
- 238000011088 calibration curve Methods 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 description 2
- YIWGJFPJRAEKMK-UHFFFAOYSA-N 1-(2H-benzotriazol-5-yl)-3-methyl-8-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carbonyl]-1,3,8-triazaspiro[4.5]decane-2,4-dione Chemical compound CN1C(=O)N(c2ccc3n[nH]nc3c2)C2(CCN(CC2)C(=O)c2cnc(NCc3cccc(OC(F)(F)F)c3)nc2)C1=O YIWGJFPJRAEKMK-UHFFFAOYSA-N 0.000 description 2
- DEXFNLNNUZKHNO-UHFFFAOYSA-N 6-[3-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperidin-1-yl]-3-oxopropyl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C1CCN(CC1)C(CCC1=CC2=C(NC(O2)=O)C=C1)=O DEXFNLNNUZKHNO-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 2
- 229910052787 antimony Inorganic materials 0.000 description 2
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 2
- UWCPYKQBIPYOLX-UHFFFAOYSA-N benzene-1,3,5-tricarbonyl chloride Chemical compound ClC(=O)C1=CC(C(Cl)=O)=CC(C(Cl)=O)=C1 UWCPYKQBIPYOLX-UHFFFAOYSA-N 0.000 description 2
- 239000008280 blood Substances 0.000 description 2
- 210000004369 blood Anatomy 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- BPHHNXJPFPEJOF-UHFFFAOYSA-J chembl296966 Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]S(=O)(=O)C1=CC(S([O-])(=O)=O)=C(N)C2=C(O)C(N=NC3=CC=C(C=C3OC)C=3C=C(C(=CC=3)N=NC=3C(=C4C(N)=C(C=C(C4=CC=3)S([O-])(=O)=O)S([O-])(=O)=O)O)OC)=CC=C21 BPHHNXJPFPEJOF-UHFFFAOYSA-J 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000010612 desalination reaction Methods 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000009616 inductively coupled plasma Methods 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 229940018564 m-phenylenediamine Drugs 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000002685 polymerization catalyst Substances 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000004154 testing of material Methods 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- 229920003169 water-soluble polymer Polymers 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229920000298 Cellophane Polymers 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 229920000219 Ethylene vinyl alcohol Polymers 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229920000433 Lyocell Polymers 0.000 description 1
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 1
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
- VCUFZILGIRCDQQ-KRWDZBQOSA-N N-[[(5S)-2-oxo-3-(2-oxo-3H-1,3-benzoxazol-6-yl)-1,3-oxazolidin-5-yl]methyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C1O[C@H](CN1C1=CC2=C(NC(O2)=O)C=C1)CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F VCUFZILGIRCDQQ-KRWDZBQOSA-N 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- 229920004935 Trevira® Polymers 0.000 description 1
- 229920002978 Vinylon Polymers 0.000 description 1
- JAWMENYCRQKKJY-UHFFFAOYSA-N [3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-ylmethyl)-1-oxa-2,8-diazaspiro[4.5]dec-2-en-8-yl]-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]methanone Chemical compound N1N=NC=2CN(CCC=21)CC1=NOC2(C1)CCN(CC2)C(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F JAWMENYCRQKKJY-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 239000003242 anti bacterial agent Substances 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- 239000002518 antifoaming agent Substances 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 239000003899 bactericide agent Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000012461 cellulose resin Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011258 core-shell material Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 125000002573 ethenylidene group Chemical group [*]=C=C([H])[H] 0.000 description 1
- 239000004715 ethylene vinyl alcohol Substances 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 150000002291 germanium compounds Chemical class 0.000 description 1
- RZXDTJIXPSCHCI-UHFFFAOYSA-N hexa-1,5-diene-2,5-diol Chemical compound OC(=C)CCC(O)=C RZXDTJIXPSCHCI-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 1
- 239000006082 mold release agent Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920006350 polyacrylonitrile resin Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- ILJSQTXMGCGYMG-UHFFFAOYSA-N triacetic acid Chemical compound CC(=O)CC(=O)CC(O)=O ILJSQTXMGCGYMG-UHFFFAOYSA-N 0.000 description 1
- 239000003232 water-soluble binding agent Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
- D21H13/10—Organic non-cellulose fibres
- D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- D21H13/24—Polyesters
-
- 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
- B01D69/107—Organic support material
- B01D69/1071—Woven, non-woven or net mesh
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
- D21H27/08—Filter paper
Definitions
- the present invention relates to a semipermeable membrane support and a method for producing a semipermeable membrane support.
- Semipermeable membranes are widely used in fields such as seawater desalination, water purifiers, food concentration, wastewater treatment, medical applications such as blood filtration, and ultrapure water production for semiconductor cleaning.
- the semipermeable membrane is made of synthetic resin such as cellulose resin, polysulfone resin, polyacrylonitrile resin, fluorine resin, and polyester resin.
- the semipermeable membrane is inferior in mechanical strength when used alone. It is used as a "separation membrane”.
- the surface of the semipermeable membrane support on which the semipermeable membrane is provided is referred to as the "applied surface", and the opposite surface is referred to as the "non-applied surface".
- a nonwoven fabric containing synthetic fibers is mainly used as the semipermeable membrane support.
- polyester-based wet-laid nonwoven fabrics are often used (see Patent Documents 1 and 2, for example).
- antimony compounds typified by antimony trioxide have been widely used as polymerization catalysts for polyester fibers constituting these semipermeable membrane supports.
- Antimony trioxide is inexpensive and has excellent catalytic activity, but in recent years, many countries, including Europe and the United States, have pointed out the problem of the safety of antimony from an environmental point of view.
- the performance required for the semipermeable membrane support is good adhesiveness between the semipermeable membrane and the semipermeable membrane support.
- the semipermeable membrane solution When applied to a support, the semipermeable membrane solution does not strike through the non-coated surface, the semipermeable membrane has few defects, and the semipermeable membrane does not separate from the semipermeable membrane support.
- the membrane When separation is performed using a semipermeable membrane, if impurities contained in the water accumulate on the surface of the semipermeable membrane, clogging the semipermeable membrane or reducing the permeation flux, the membrane may be washed with a high-pressure water stream. If the peel strength between the semipermeable membrane and the semipermeable membrane support is low, the semipermeable membrane will be peeled from the semipermeable membrane support, damaging the semipermeable membrane and making it impossible to obtain sufficient membrane performance. Further, when the semipermeable membrane is stopped from operating at high pressure, the semipermeable membrane separates from the semipermeable membrane support due to backflow of the permeated water, and the performance of the semipermeable membrane deteriorates.
- the nonwoven fabric is formed.
- the fiber concentration of the fiber slurry is 0.01 to 0.1% by mass, and a water-soluble polymer having a molecular weight of 5 million or more is added to the fiber slurry as a polymer viscosity agent, based on the fiber content.
- a method of making paper with a content of 15% by mass has been proposed (see, for example, Patent Document 3).
- a semipermeable membrane support has been proposed (see, for example, Patent Document 4). Specifically, a semipermeable membrane support with a thick fiber layer as the application surface and a thin fiber layer as the non-application surface, a thin fiber layer sandwiched between thick fiber layers, and both the application surface and the non-application surface are thick fiber layers. A semipermeable membrane support is described.
- the uniformity of the semipermeable membrane support is low, and the permeation of the semipermeable membrane becomes uneven.
- the separation membrane using the above semipermeable membrane support is operated at high pressure, there is a problem of membrane peeling.
- the semipermeable membrane tends to have defects due to its low smoothness.
- the semipermeable membrane solution penetrates into the inside of the semipermeable membrane support, and a large amount of the semipermeable membrane solution is required in order to obtain the desired thickness of the semipermeable membrane.
- Patent Document 1 proposes a method of adjusting the air permeability and pore size of a semipermeable membrane support for the purpose of improving the adhesiveness between the semipermeable membrane and the semipermeable membrane support and preventing strike-through.
- the permeability according to JIS L1096 is calculated based on the amount of air that permeates from one side of the semipermeable membrane support to another side through the inside of the semipermeable membrane support. It does not accurately reflect the strike-through of the semipermeable membrane solution applied to the surface to the non-coated surface. Therefore, when a semipermeable membrane solution is applied to a semipermeable membrane support having air permeability within the range shown in Patent Document 1, the semipermeable membrane solution may strike through.
- the sum of the weight A per unit of the semipermeable membrane support and the weight B of the dope permeating the semipermeable membrane support (permeation amount)
- composite semipermeable membrane has been provided (for example, Patent Document 5). Strike-through sometimes occurred from the surface to the back surface (non-coated surface).
- Patent Document 6 when a semipermeable membrane solution is applied to a defective portion existing locally on a wet-laid nonwoven fabric sheet as a semipermeable membrane support, the permeability of the semipermeable membrane solution is partially changed.
- the thickness of the semipermeable membrane in this part may become extremely thin and the surface of the semipermeable membrane may become wrinkled due to the fact that it becomes difficult to penetrate through the wet-laid nonwoven fabric.
- Patent Document 6 there is no low density defect, it is uniform, the semipermeable membrane and the semipermeable membrane support have good adhesion, and the semipermeable membrane solution penetrates the wet-laid nonwoven fabric too much, resulting in uneven semipermeable membranes.
- a semipermeable membrane support capable of preventing this, a semipermeable membrane support with adjusted sheet density and pressure loss has been proposed.
- the semipermeable membrane may have defects due to the convex portions of the semipermeable membrane support.
- Patent Document 7 a support for a semipermeable membrane for membrane separation activated sludge treatment is obtained which has few defects that occur in the process of forming a semipermeable membrane and has good adhesiveness to a resin frame that holds the semipermeable membrane. Therefore, a nonwoven fabric containing stretched polyester fibers and unstretched polyester fibers, having a density of 0.50 to 0.70 g/cm 3 and an internal bonding strength of 490 mJ or more. Supports for semipermeable membranes for separation activated sludge treatment have been proposed. In Examples, the surface strength of the semipermeable membrane support is evaluated. Specifically, a transparent adhesive tape is evenly attached to the surface of the semipermeable membrane support so that air does not enter. Visually evaluate the state of the fibers remaining in the adhesive tape, evaluate whether the fibers stick to the adhesive tape, and use it as an indicator of fiber dropout when providing a semipermeable membrane. Defects were not evaluated.
- the basis weight is in the range of 10 to 200 g/m 2 and the maximum height of the surface roughness of the front or back surface is A semipermeable membrane support has been proposed, characterized in that the surface roughness is within 500 ⁇ m and the difference in surface roughness between the front and back surfaces is 30 ⁇ m or more.
- the semipermeable membrane is applied to the semipermeable membrane support obtained in the examples and the processability is evaluated, the evaluation of the defects of the semipermeable membrane caused by the semipermeable membrane support and the semipermeable membrane formation are difficult. Post-membrane salt rejection was not evaluated.
- a first object of the present invention is to provide a semipermeable membrane support that has few defects of the semipermeable membrane, that the semipermeable membrane solution is less likely to strike through, and that the peel strength between the semipermeable membrane and the semipermeable membrane support is improved. It is to be.
- the second object of the present invention is to provide a semipermeable membrane support that has fewer defects of the semipermeable membrane and has an improved salt blocking rate.
- the fiber orientation strength of the application surface on which the semipermeable membrane is provided is 1.00 or more and 1.30 or less, and The fiber orientation strength of the coated surface is 1.00 or more and 1.50 or less, and remains on the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support
- a semipermeable membrane support made of a wet-laid nonwoven fabric containing main synthetic fibers and binder synthetic fibers the number of detached fibers is 30 or less in a tape peeling test, and the semipermeable membrane is provided by a confocal laser microscope.
- a support for a semipermeable membrane, wherein the difference in level of the core obtained by measuring the surface roughness of the coated surface is 14 ⁇ m or less.
- a semipermeable membrane support is obtained in which the defects of the semipermeable membrane are few, the semipermeable membrane solution is hard to strike through, and the membrane peel strength between the semipermeable membrane and the semipermeable membrane support is improved. be able to.
- the semipermeable membrane support of the present invention (1) is a semipermeable membrane support made of a wet-laid nonwoven fabric containing main synthetic fibers and binder synthetic fibers, wherein the fiber orientation strength of the coated surface on which the semipermeable membrane is provided is 1.5. 00 or more and 1.30 or less, the fiber orientation strength of the non-coated surface is 1.00 or more and 1.50 or less, and the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support.
- the average area of the semipermeable membrane remaining on the coated surface of the permeable membrane support is 500 ⁇ m 2 or less, and the residual rate of the semipermeable membrane is 2.5% or more and 5.0% or less.
- Fiber orientation strength is the fiber orientation (anisotropy) of only the fibers present in the surface layer rather than the entire semipermeable membrane support, and is expressed by the tensile strength ratio in the MD and CD directions. It is very different from orientation.
- a method for confirming the orientation of fibers existing on the surface layer of the semipermeable membrane support there is a method of measuring the "orientation angle" of each fiber existing on the surface layer with the MD direction set at 0°.
- the “strength of fiber orientation” measures the degree of anisotropy, and is very different from the "orientation angle”.
- the fiber orientation strength of the coating surface on which the semipermeable membrane is provided is 1.00 or more and 1.30 or less, more preferably 1.00 or more and 1.25 or less, and 1.00 or more and 1.20. More preferred are: When the fiber orientation strength is 1.00 or more and 1.10 or less, it means that the fibers are in a nearly unoriented state. When the fiber orientation strength of the coating surface of the semipermeable membrane support exceeds 1.30, the distance between the fibers on the surface of the semipermeable membrane support becomes narrow, which impedes the permeation of the semipermeable membrane and reduces the membrane peel strength. There is a risk of decline.
- the fiber orientation strength of the non-coated surface is 1.00 or more and 1.50 or less, more preferably 1.00 or more and 1.40 or less, and even more preferably 1.00 or more and 1.30 or less. If the fiber orientation strength of the non-applied surface of the semipermeable membrane support exceeds 1.50, permeation of the semipermeable membrane solution from the applied surface side to the non-applied surface side is inhibited, and the membrane peel strength may decrease. .
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support is 500 ⁇ m 2 or less. , 450 ⁇ m 2 or less, and even more preferably 400 ⁇ m 2 or less. If the average area exceeds 500 ⁇ m 2 , the permeation of the semipermeable membrane into the semipermeable membrane support becomes uneven, and the anchoring effect is reduced, which may reduce the membrane peel strength.
- the residual rate of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support is 2.5% or more and 5.0% or less. , more preferably 2.7% or more and 5.0% or less, and even more preferably 3.0% or more and 5.0% or less. If the residual ratio exceeds 5.0%, the semipermeable membrane may permeate excessively into the semipermeable membrane support, causing strike-through of the semipermeable membrane. If the residual rate is less than 2.0%, a sufficient anchoring effect cannot be obtained, the membrane peeling strength is lowered, and the semipermeable membrane may be peeled off.
- the semipermeable membrane support of the present invention (2) is made of a wet-laid nonwoven fabric containing main synthetic fibers and binder synthetic fibers, has 30 or less detached fibers in a tape peeling test, and is measured by a confocal laser microscope.
- the level difference of the core portion obtained by measuring the surface roughness of the coated surface on which the semipermeable membrane is provided is 14 ⁇ m or less.
- detached fibers are counted as single fibers unless otherwise specified. That is, each fiber is counted for a fiber bundle in which two or more fibers are in close contact with each other and exist in a parallel bundle shape.
- the semipermeable membrane support of the present invention (2) is a semipermeable membrane support having 30 or less detached fibers in a tape peeling test.
- Detachment fibers are fibers that are loosely bonded between the main synthetic fiber and the binder synthetic fiber and are detached from the surface of the semipermeable membrane support due to physical impact or rubbing.
- the number of detached fibers is 30 or less, preferably 20 or less, and even more preferably 10 or less. If the number of detached fibers exceeds 30, the fibers break through the surface of the semipermeable membrane during the formation of the semipermeable membrane, causing membrane defects and lowering the salt rejection rate.
- the semipermeable membrane support of the present invention (2) is characterized in that the level difference Sk of the core portion obtained by measuring the surface roughness of the coated surface on which the semipermeable membrane is provided is 14 ⁇ m or less with a confocal laser microscope. and
- the level difference Sk of the core portion is an index for comparing surface roughness, and is the difference between the upper level and the lower level of the core portion conforming to ISO25178.
- Sk When Sk is 14 ⁇ m or less, semipermeable membrane defects during semipermeable membrane formation are reduced, and the salt blocking rate after semipermeable membrane formation is less likely to decrease.
- Sk is more preferably 13 ⁇ m or less, still more preferably 12 ⁇ m or less, and particularly preferably 11.5 ⁇ m or less.
- Sk exceeds 14 ⁇ m, the thickness of the semipermeable membrane provided on the semipermeable membrane support becomes uneven, and defects occur at portions where the semipermeable membrane is thin, resulting in deterioration of membrane performance.
- the lower limit of Sk is preferably 8 ⁇ m. If Sk is less than 8 ⁇ m, the adhesiveness between the semipermeable membrane and the semipermeable membrane support may decrease.
- Methods for making the Sk of the semipermeable membrane support 14 ⁇ m or less include the following.
- (I) Improvement of fiber dispersibility by two-stage dispersion (II) Optimization of blending design (fiber selection and binder synthetic fiber content)
- (III) Optimization of papermaking conditions for base paper (IV) Adjustment of hot-pressing conditions can be performed singly or in combination for control. Among them, it is preferable to perform (I).
- the antimony (Sb) element elution amount in the main synthetic fiber or the binder synthetic fiber is preferably less than 5 ⁇ g/g, more preferably less than 1 ⁇ g/g.
- the Sb element elution amount in the main synthetic fiber or the binder synthetic fiber is less than 5 ⁇ g/g, the fiber dispersibility during papermaking of the semipermeable membrane support is improved.
- detachment fibers generated from the semipermeable membrane support can be suppressed, and the effect of improving the membrane peel strength after the formation of the semipermeable membrane can be easily obtained.
- the main synthetic fiber and the binder synthetic fiber having an Sb element elution amount of less than 5 ⁇ g/g do not use antimony compounds as polymerization catalysts, or use less antimony compounds, for example, titanium compounds, germanium compounds, aluminum compounds, etc. It is commercially available as a fiber with For example, manufacturers and sellers include Teijin Frontier Co., Toray Industries, South Asia Plastics Co., Ltd., Far East New Century Co., Ltd., Trevira Co., Advansa Co., Nirmal Fibers Co., and the like. It can be obtained as short fibers having a fiber length suitable for wet-laid nonwoven fabrics, or it is possible to obtain continuous long fibers and cut them into fiber lengths suitable for wet-laid nonwoven fabrics.
- the Sb element elution amount of the semipermeable membrane support is preferably less than 1.5 ⁇ g/g, and more preferably the Sb elution amount of the semipermeable membrane support is less than 1.0 ⁇ g/g.
- the fiber dispersibility of the semipermeable membrane support during papermaking is improved.
- the effect of improving the film peeling strength after forming the semipermeable film is likely to be obtained.
- detachment fibers generated from the semipermeable membrane support can be suppressed, and the effect of improving the salt blocking rate after semipermeable membrane formation can be easily obtained.
- the "antimony element elution amount" in the present invention means that the fiber or semipermeable membrane support is immersed in ultrapure water with a specific resistance of 18.2 M ⁇ cm and a temperature of 25°C for 24 hours, and Sb eluted in the ultrapure water. It is calculated using ⁇ Formula 1> from the value obtained by quantitatively analyzing the amount of element by ICP-MS (Inductively Coupled Plasma-Mass Spectro-metry).
- the main synthetic fiber is a fiber that forms the skeleton of the semipermeable membrane support. It is a fiber that maintains its shape.
- main synthetic fibers include polyolefin-based, polyamide-based, polyacrylic-based, vinylon-based, vinylidene-based, polyvinyl chloride-based, polyester-based, benzoate-based, polychlal-based, and phenol-based fibers. , polyester fibers with high heat resistance are more preferable.
- semi-synthetic fibers such as acetate, triacetate, and promix, and regenerated fibers such as rayon, cupra, and lyocell fibers may be contained as long as the performance is not impaired.
- the fiber diameter of the main synthetic fiber is not particularly limited, it is preferably 30 ⁇ m or less, more preferably 2 to 20 ⁇ m, even more preferably 4 to 20 ⁇ m, and particularly preferably 6 to 20 ⁇ m.
- the fiber diameter exceeds 30 ⁇ m, the main synthetic fibers on the surface of the wet-laid nonwoven fabric tend to stand up, and may penetrate the semipermeable membrane, resulting in defects of the semipermeable membrane or lowering the membrane performance. If the fiber diameter is less than 2 ⁇ m, the semipermeable membrane solution may not easily permeate the semipermeable membrane support, and the adhesiveness between the semipermeable membrane and the semipermeable membrane support may deteriorate.
- the fiber diameter of the main synthetic fiber exceeds 30 ⁇ m
- the fiber orientation strength of the coated surface exceeds 1.30
- the orientation strength of the non-coated surface exceeds 1.50
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the membrane and the semipermeable membrane support exceeds 500 ⁇ m 2
- the penetration of the semipermeable membrane solution may occur.
- the fiber diameter of the main synthetic fiber exceeds 30 ⁇ m
- penetration of the semipermeable membrane solution may occur.
- the fiber diameter is the diameter of the fiber obtained by measuring the cross-sectional area of the fiber forming the semipermeable membrane support by observing the cross section of the semipermeable membrane support with a scanning electron microscope and converting the area into a perfect circle.
- the cross section of the fiber is the cross section of the fiber cut perpendicularly to the length direction of the fiber.
- the fiber length of the main synthetic fiber is not particularly limited, it is preferably 1 to 15 mm, more preferably 1 to 12 mm, still more preferably 3 to 10 mm, and particularly preferably 4 to 6 mm. If the fiber length is less than 1 mm, the strength of the semipermeable membrane support is insufficient and the semipermeable membrane support may be broken. If the fiber length exceeds 15 mm, the fiber dispersibility tends to decrease, and the formation of the semipermeable membrane support may become uneven, or the film formability of the semipermeable membrane may be impaired. In addition, in the present invention (1), the fiber orientation strength of the coated surface may exceed 1.30, or the orientation strength of the non-coated surface may exceed 1.50.
- the cross-sectional shape of the main synthetic fibers is preferably circular, and the cross-sectional aspect ratio (fiber cross-sectional major diameter/fiber cross-sectional minor diameter) of the fibers before being dispersed in water in the papermaking process is preferably 1.0 or more and less than 1.2. . If the cross-sectional aspect ratio is 1.2 or more, the fiber dispersibility may be reduced, or the uniformity of the semipermeable membrane support and the smoothness of the coating surface may be adversely affected due to the occurrence of entanglement or tangling of the fibers. be.
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support may exceed 500 ⁇ m 2 .
- fibers having irregular cross sections such as T-shaped, Y-shaped, and triangular can also be contained within a range that does not impair other properties such as fiber dispersibility for the purpose of preventing strike-through and achieving surface smoothness.
- the aspect ratio (fiber length/fiber diameter) of the main synthetic fiber is preferably 200-1000, more preferably 220-900, still more preferably 280-800.
- the aspect ratio is less than 200, the dispersibility of the fibers is good, but the fibers may drop off from the papermaking net during papermaking, or the fibers may stick into the papermaking net, resulting in poor releasability from the papermaking net. sometimes.
- the aspect ratio exceeds 1000, although it contributes to the formation of a three-dimensional network of fibers, the uniformity of the semipermeable membrane support and the smoothness of the coating surface are adversely affected due to the occurrence of entanglement and tangling of the fibers. In some cases, detachment fibers may occur, and membrane defects may occur during the formation of the semipermeable membrane.
- Sk may exceed 14 ⁇ m.
- the content of the main synthetic fiber is preferably 40 to 90% by mass, more preferably 50 to 80% by mass, and even more preferably 60 to 75% by mass in the wet-laid nonwoven fabric related to the semipermeable membrane support of the present invention. If the content of the main synthetic fiber is less than 40% by mass, the liquid permeability may deteriorate. On the other hand, if the content exceeds 90% by mass, the semipermeable membrane support may be torn due to frequent generation of detached fibers or insufficient strength.
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support is 500 ⁇ m 2 . may exceed.
- the semipermeable membrane support of the present invention contains binder synthetic fibers.
- the binder synthetic fiber improves the mechanical strength of the semipermeable membrane support.
- the semipermeable membrane support can be produced by a wet papermaking method, followed by a drying step to soften or melt the binder synthetic fibers.
- Binder synthetic fibers include core-sheath fibers (core-shell type), parallel fibers (side-by-side type), composite fibers such as radial split fibers, and undrawn fibers.
- Composite fibers are less likely to form a film, so that the mechanical strength can be improved while maintaining the space of the semipermeable membrane support. More specifically, a combination of polypropylene (core) and polyethylene (sheath), a combination of polypropylene (core) and ethylene vinyl alcohol (sheath), a combination of high-melting polyester (core) and low-melting polyester (sheath), polyester, etc. of undrawn fibers.
- monofilaments composed only of low melting point resins such as polyethylene and polypropylene, and hot water-soluble binders such as polyvinyl alcohol tend to form a film during the drying process of the semipermeable membrane support.
- a combination of a high melting point polyester (core) and a low melting point polyester (sheath) and undrawn polyester fibers can be preferably used, and undrawn polyester fibers can be more preferably used.
- the fiber diameter of the binder synthetic fiber is not particularly limited, it is preferably 2 to 20 ⁇ m, more preferably 5 to 15 ⁇ m, still more preferably 7 to 13 ⁇ m. Moreover, it is preferable that the fiber diameter is different from that of the main synthetic fiber. Since the fiber diameter is different from that of the main synthetic fiber, it also plays a role of forming a uniform three-dimensional network together with the main synthetic fiber. Furthermore, in the step of raising the temperature to the softening temperature or the melting temperature of the binder synthetic fiber or higher, the smoothness of the surface of the semipermeable membrane support can also be improved. be.
- the fiber length of the binder synthetic fiber is not particularly limited, it is preferably 1 to 12 mm, more preferably 3 to 10 mm, and even more preferably 4 to 6 mm.
- the cross-sectional shape of the binder synthetic fiber is preferably circular, but fibers with irregular cross-sections such as T-shaped, Y-shaped, and triangular may also be used for preventing strike-through, smoothness of the coated surface, and adhesiveness between non-coated surfaces. It can be contained within a range that does not impair the characteristics of.
- the aspect ratio (fiber length/fiber diameter) of the binder synthetic fiber is preferably 200-1000, more preferably 300-800, and even more preferably 400-700.
- the aspect ratio is less than 200, the dispersibility of the fibers is good, but the fibers may drop off from the papermaking net during papermaking, or the fibers may stick into the papermaking net, resulting in poor releasability from the papermaking net.
- the aspect ratio exceeds 1000, although the binder synthetic fiber contributes to the formation of a three-dimensional network, the uniformity of the wet-laid nonwoven fabric and the smoothness of the coated surface are adversely affected due to the possibility of entanglement of the fibers and the occurrence of tangles. may affect
- (1) detached fibers may occur, and membrane defects may occur during the formation of the semipermeable membrane.
- Sk may exceed 14 ⁇ m.
- the content of the binder synthetic fiber is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 25 to 40% by mass, relative to the wet-laid nonwoven fabric related to the semipermeable membrane support of the present invention.
- the content of the binder synthetic fibers is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 25 to 40% by mass, relative to the wet-laid nonwoven fabric related to the semipermeable membrane support of the present invention.
- the method for manufacturing the semipermeable membrane support of the present invention will be explained.
- the semipermeable membrane support of the present invention is a wet-laid nonwoven fabric, and is produced by preparing a base paper by a wet-laid papermaking method and subjecting the base paper to heat-pressing with hot rolls.
- synthetic binder fibers are uniformly dispersed in water using a dispersing device such as a pulper. do. After that, through a process such as screening (removal of foreign matter, lumps, etc.), slurry diluted with white water (dilution water) to a final fiber concentration of 0.01 to 0.50% by mass is made by a paper machine. A wet paper web is obtained. Stirring the diluted slurry with a stirrer is preferable because it promotes the formation of single fibers from the fiber bundle. Chemicals such as dispersants, antifoaming agents, hydrophilic agents, antistatic agents, polymeric viscosity agents, mold release agents, antibacterial agents, and bactericides may be added during the process to ensure uniform dispersibility of fibers. be.
- the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support after the formation of the semipermeable membrane is 500 ⁇ m 2 or less, and the remaining rate of the semipermeable membrane is 2.5% or more and 5.0% or less, and the production of the semipermeable membrane support of the present invention (2)
- the method describes how to reduce the shedding fibers.
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support after the formation of the semipermeable membrane, and the residual rate of the semipermeable membrane In order to control , or to reduce the number of detached fibers, it is important to disperse the main synthetic fibers and the binder synthetic fibers in water in a fiber dispersing device (pulper) to loosen the fiber bundles into single fibers.
- pulper fiber dispersing device
- Methods for unraveling into single fibers include adding a dispersant, optimizing the shape of the blades of the pulper, optimizing the clearance between the bottom surface of the pulper and the blades, and installing a barrier plate on the wall surface of the pulper tank.
- the diluted fiber dispersion is dispersed with a stirring device to obtain single fibers. You can increase the degree of transformation.
- the degree of single filamentization is further increased.
- the binder synthetic fibers are dispersed, and then the main synthetic fibers are dispersed. It is characterized by producing a semipermeable membrane support by a method.
- the binder synthetic fiber is put in first and dispersed, and then the main synthetic fiber is put in and dispersed. It becomes possible for the binder synthetic fibers that are monofilamentized to cover the main synthetic fibers. Therefore, in the present invention (1), a semipermeable membrane support having fine and uniform pores can be produced.
- the fiber orientation strength of is 1.00 or more and 1.50 or less, and the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support after the formation of the semipermeable membrane It is easy to obtain a semipermeable membrane support in which the average area of the semipermeable membrane remaining on the substrate is 500 ⁇ m 2 or less and the semipermeable membrane survival rate is 2.5% or more and 5.0% or less. In addition, according to the present invention (2), detachment of fibers from the semipermeable membrane support can be suppressed.
- a fiber dispersion is supplied onto a papermaking net, and excess water is squeezed out to obtain a wet paper.
- the paper As the paper is formed, it is gradually squeezed under the papermaking mesh.
- the formation of the wet paper on the paper mesh progresses with the accumulation of fibers on the surface of the paper mesh, and the formation of the wet paper is completed upon completion of water squeezing.
- the fibers are deposited in the dispersed state of the fiber dispersion supplied on the papermaking net, so the surface in contact with the papermaking net (hereinafter, the "surface in contact with the papermaking net" is referred to as the "papermaking net surface").
- the unraveling state of the fibers in becomes uniform.
- the fiber dispersion is still present on the wet paper being formed on the paper mesh, and the formation of the wet paper is completed depending on the position of the water squeezed by suction, the strength of the suction, the speed of the paper mesh, the flow rate of the fiber dispersion, etc. It is possible to adjust the unraveling state of the fibers on the surface opposite to the papermaking net surface (hereinafter, the "surface opposite to the papermaking net surface” may be referred to as the "papermaking felt surface”).
- the papermaking felt surface is less uniform in the unraveled state of the fibers. Further, in the middle to the latter half of wet paper formation, if the main synthetic fibers and the binder synthetic fibers have different thicknesses and lengths, the fibers of the same kind may gather together due to suction, resulting in a further decrease in uniformity. The clustering of the binder synthetic fibers may lead to areas where the binder synthetic fibers are partially lacking. Therefore, in the present invention (1), the fiber orientation strength of the papermaking net surface of the wet nonwoven fabric is lower than the fiber orientation strength of the papermaking felt surface.
- the peel strength between the semipermeable membrane and the semipermeable membrane support is increased.
- the surface strength of the papermaking net surface of the wet-laid nonwoven fabric is higher than the surface strength of the papermaking felt surface.
- the salt blocking rate is improved during the formation of the semipermeable membrane.
- the base paper obtained by drying the wet paper obtained by the wet papermaking method is preferably subjected to heat pressure processing (heat calendering) using hot rolls.
- heat calendering heat pressure processing
- the base paper is passed between nipped rolls and is heat-pressed to melt and soften the binder synthetic fibers and fix the main synthetic fibers. do. If there is a portion where the binder synthetic fiber does not exist in the base paper, large pores are formed in the semipermeable membrane support in the present invention (1), and the interface between the semipermeable membrane and the semipermeable membrane support after the semipermeable membrane is formed.
- the semipermeable membrane When the semipermeable membrane is peeled off, the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support becomes large, making it difficult to obtain the anchoring effect for improving the membrane peel strength.
- the semipermeable membrane is pierced by the detached fibers, resulting in membrane defects. Therefore, it is important to convert the binder synthetic fibers into single fibers in the base paper in the wet papermaking method and to disperse the binder synthetic fibers and the main synthetic fibers.
- the fiber orientation strength of the coated surface and non-coated surface of the semipermeable membrane support, and the residual area and residual rate of the semipermeable membrane after peeling off the semipermeable membrane are controlled. be able to.
- detachment fibers can be suppressed.
- a fourdrinier, a cylinder, or an inclined wire method can be used as the papermaking method.
- a paper machine with one papermaking system selected from these papermaking system groups, or a combination paper machine with two or more of the same or different papermaking systems selected from these papermaking system groups installed online. can do.
- a "paper-making method” in which wet papers made by each paper machine are laminated, or after forming one layer, the layer is A "casting method" or the like can be used in which a separate layer is formed by casting a slurry on which fibers are dispersed.
- the semipermeable membrane support has a fiber orientation strength of 1.00 or more and 1.30 or less on the coated surface, and a fiber orientation strength of 1.00 or more and 1.50 or less on the non-coated side of the semipermeable membrane support.
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane support and the semipermeable membrane support is 500 ⁇ m 2 or less, and the semipermeable membrane survival rate is 2.
- any paper machine it is preferable to adjust so that the difference between the flow velocity when the slurry lands on the papermaking wire from the headbox and the wire speed is small. Furthermore, it is important to dewater the slurry by drawing water as soon as possible after it comes into contact with the papermaking wire to immobilize the fibers. For this purpose, the concentration during wet papermaking (amount of water to be made), the papermaking speed, the relative speed of the slurry flow rate and the papermaking wire (J/W ratio), the dehydration pressure in the wire part, and the tension balance in the dryer part are adjusted singly or in combination. You can control it by doing it.
- the base paper is obtained by drying the wet paper produced by the paper machine with a Yankee dryer, air dryer, cylinder dryer, suction drum dryer, infrared dryer, or the like.
- a hot roll such as a Yankee dryer and dried under heat and pressure, thereby improving the smoothness of the contacted surface.
- Hot and pressure drying means drying by pressing the wet paper against a hot roll with a touch roll or the like.
- the surface temperature of the heat roll is preferably 100 to 180°C, more preferably 100 to 160°C, even more preferably 110 to 160°C.
- the pressing pressure is preferably 50-1000 N/cm, more preferably 100-800 N/cm.
- the Sk of the semipermeable membrane support is affected by the surface smoothness of the wet paper and hot-press drying with a hot roll, so it is necessary to adjust the pressing pressure of the wet paper against the hot roll during hot-press drying. Even if the surface of the wet paper web is rough or uneven, the Sk of the semipermeable membrane support can be adjusted by adjusting the surface temperature of the hot roll and the pressure of the wet paper web against the hot roll. can be done.
- the pressing pressure of the wet paper against the heat roll is set relatively high during hot-press drying, and is more preferably 300 to 800 N/cm. .
- the surface whose smoothness is improved by bringing it into close contact with a hot roll such as a Yankee dryer is attached to the semipermeable membrane support. It is also effective to use it as the coating surface of the support.
- the base paper is subjected to heat-pressure processing by passing the base paper between nipped rolls.
- Combinations of rolls include two metal rolls, a metal roll and a resin roll, a metal roll and a cotton roll, and the like. At least one of the two rolls is heated and used as a hot roll. Primarily, metal rolls are used as hot rolls. It is also possible to perform hot-pressing with hot rolls twice or more. You can process it twice. If necessary, the front and back of the base paper may be reversed.
- a desired semipermeable membrane support can be obtained by controlling the surface temperature of the hot rolls, the nip pressure between the rolls, and the processing speed of the base paper.
- the binder synthetic fiber is optimally melted and softened during hot-press processing with hot rolls to hold the fluff. This can prevent future defects.
- by controlling the processing speed it is possible to adjust, to some extent, the holding of fluff by the binder synthetic fibers.
- the degree of hold of the fluffy binder synthetic fiber can be increased.
- the present invention (2) in order to make the Sk of the semipermeable membrane support 14 ⁇ m or less, it is necessary to optimize the conditions of the hot pressing process. Semipermeable membrane defects can be prevented by adjusting the conditions of the hot-pressing process and improving the smoothness of the coating surface. For this purpose, it is important to raise the temperature of the hot rolls to around the melting point of the binder synthetic fiber, control the processing speed to apply a sufficient amount of heat to the semipermeable membrane support, and increase the nip pressure.
- the temperature of the hot roll is preferably within the range of -50°C to -10°C with respect to the melting point of the binder synthetic fiber. It is more preferably in the range of -40°C to -15°C, still more preferably in the range of -30°C to -15°C. If the temperature of the hot roll in the hot-pressing process is below ⁇ 50° C. relative to the melting point of the binder synthetic fiber, the temperature of the binder synthetic fiber does not rise sufficiently, resulting in poor adhesion to the main synthetic fiber, resulting in a semipermeable membrane support. In some cases, the strength of the fiber is lowered, and detachment fibers may occur.
- the base paper is less likely to be crushed, and the Sk of the coated surface of the semipermeable membrane support may exceed 14 ⁇ m.
- the binder synthetic fiber is deactivated, the adhesion between the binder synthetic fiber and the main synthetic fiber becomes insufficient, and detached fibers occur. Otherwise, the semipermeable membrane support tends to stick to the heat roll, and the surface of the semipermeable membrane support may become uneven.
- the fiber orientation strength of the coated surface may exceed 1.30, or the fiber orientation strength of the non-coated surface may exceed 1.50.
- the Sk of the coated surface of the semipermeable membrane support may exceed 14 ⁇ m.
- the nip pressure of the rolls in hot pressing is preferably 19 to 180 kN/m, more preferably 45 to 140 kN/m. If the nip pressure is less than 19 kN/m, the adhesion between the heat roll and the base paper is low, causing fluffing of the fibers and the occurrence of detached fibers.
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support exceeds 500 ⁇ m 2 .
- the Sk of the semipermeable membrane support may exceed 14 ⁇ m.
- the roll life may be shortened by increasing the excessive load on the roll.
- the working speed in hot-pressing is preferably 4 to 100 m/min, more preferably 10 to 80 m/min. If the processing speed is less than 4 m/min, the productivity is inferior, the density of the semipermeable membrane support is increased, the air permeability is decreased, the semipermeable membrane solution is difficult to penetrate, and the semipermeable membrane and the semipermeable membrane are separated. Adhesion of the support may decrease. On the other hand, when the processing speed exceeds 100 m/min, the heat transfer to the base paper becomes insufficient, and the main synthetic fibers become fluffed, which may result in the generation of detached fibers.
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support may exceed 500 ⁇ m 2 .
- the Sk of the semipermeable membrane support may exceed 14 ⁇ m.
- the basis weight of the semipermeable membrane support is not particularly limited, but is preferably 20 to 150 g/m 2 , more preferably 50 to 100 g/m 2 . If the basis weight is less than 20 g/m 2 , sufficient tensile strength may not be obtained and the semipermeable membrane support may break. On the other hand, if the basis weight exceeds 150 g/m 2 , the liquid permeation resistance may increase, or the thickness may increase, and a specified amount of semipermeable membrane may not be accommodated in the unit or module.
- the density of the semipermeable membrane support is preferably 0.5 to 1.0 g/cm 3 , more preferably 0.6 to 0.9 g/cm 3 . If the density is less than 0.5 g/cm 3 , the thickness will increase, and the area of the semipermeable membrane that can be incorporated into the unit will decrease, resulting in a shortened life of the semipermeable membrane. . On the other hand, when the density exceeds 1.0 g/cm 3 , the semipermeable membrane solution is less likely to permeate the semipermeable membrane support, and the adhesiveness between the semipermeable membrane and the semipermeable membrane support may deteriorate. , the liquid permeability during the formation of the semipermeable membrane may be lowered, and the life of the semipermeable membrane may be shortened.
- the thickness of the semipermeable membrane support is preferably 50 to 150 ⁇ m, more preferably 60 to 130 ⁇ m, even more preferably 70 to 120 ⁇ m. If the thickness exceeds 150 ⁇ m, the area of the semipermeable membrane that can be incorporated into the unit is reduced, and as a result, the life of the semipermeable membrane may be shortened. On the other hand, if the thickness is less than 50 ⁇ m, the semipermeable membrane may not have sufficient tensile strength or may have low liquid permeability, shortening the life of the semipermeable membrane.
- PET fiber 1-1 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 7.5 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.12 ⁇ g/g.
- PET fiber 1-2 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 7.5 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.01 ⁇ g/g.
- PET fiber 1-3 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 7.5 ⁇ m, a fiber length of 6 mm, and an Sb element elution amount of 10.3 ⁇ g/g.
- PET fiber 1-4 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 12.5 ⁇ m, a fiber length of 5 mm, and an Sb elution amount of 11.9 ⁇ g/g.
- PET fiber 1-5 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 10.5 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.04 ⁇ g/g.
- PET fiber 1-6 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 13.6 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.01 ⁇ g/g.
- PET fiber 1-7 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 11.8 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 2.3 ⁇ g/g.
- the resulting base paper was subjected to heat calendering with a combination of metal roll (heat roll) and elastic roll, or with a heat calender with a combination of metal roll (heat roll) and metal roll (heat roll).
- Semipermeable membrane supports of Examples 1-1 to 1-20 and Comparative Examples 1-1 to 1-8 were obtained under the thermal calendering conditions described in .
- the surface (processed surface) of the base paper in contact with the metal roll (heat roll) is used as the coated surface
- the processed surface is , opposite to the first stage.
- the semipermeable membrane support subjected to heat calendering by a combination of a metal roll (heat roll) and a metal roll (heat roll) was used as the coating surface on the circular mesh surface.
- Basis Weight The basis weight was measured according to JIS P8124:2011.
- a separation functional layer to obtain a separation membrane in which a composite semipermeable membrane comprising a porous polysulfone membrane and a separation functional layer was provided on the coated surface of the semipermeable membrane support.
- the obtained separation membrane was used for the following average area measurement of the remaining semipermeable membrane, measurement of the residual rate of the semipermeable membrane, defect evaluation of the semipermeable membrane, and membrane peel strength evaluation.
- a transparent sheet is superimposed on the copy of the obtained mapping image, and using a black pen or the like, the detection portion of the sulfur (S) element is blacked out, and then the transparent sheet is copied onto a blank paper to obtain a sulfur (S) element. Detected parts were clearly distinguished by black and non-detected parts by white. When the sulfur (S) element detection portion was in contact with the boundary of the mapping image, it was not regarded as a measurement target.
- a transparent sheet is superimposed on the copy of the obtained mapping image, and using a black pen or the like, the detection portion of the sulfur (S) element is blacked out, and then the transparent sheet is copied onto a blank paper to obtain a sulfur (S) element. Detected parts were clearly distinguished by black and non-detected parts by white. When the sulfur (S) element detection portion was in contact with the boundary of the mapping image, it was not regarded as a measurement target.
- the occupancy of sulfur element in the mapping image was calculated.
- the occupancy rate of the sulfur element in the mapping image is calculated from the total area of each sulfur (S) element detection portion and the mapping image area, and the average value of the five measurement points is the "semipermeable membrane survival rate”.
- the semipermeable membrane supports of Examples 1-1 to 1-20 consisted of a wet-laid nonwoven fabric containing main synthetic fibers and binder synthetic fibers, and the fiber orientation strength of the application surface on which the semipermeable membrane was provided was 1.00 or more. 1.30 or less, the fiber orientation strength of the non-coated surface is 1.00 or more and 1.50 or less, and the semipermeable membrane support when the semipermeable membrane is peeled off at the interface between the semipermeable membrane and the semipermeable membrane support
- the average area of the semipermeable membrane remaining on the coated surface is 500 ⁇ m 2 or less, and the residual rate of the semipermeable membrane is 2.5% or more and 5.0% or less. It was found that the membrane hardly penetrated and the membrane peel strength between the semipermeable membrane and the semipermeable membrane support was high.
- Example 1-1 and Examples 1-5 to 1-8 From the comparison of Example 1-1 and Examples 1-5 to 1-8 and the comparison of Example 1-9 and Examples 1-11 to 1-12, the coated surface and the non-coated surface of the semipermeable membrane support It can be seen that the fiber orientation strength can be adjusted by the papermaking conditions and fiber blending.
- the fiber orientation strength of the coated surface is 1.00 or more and 1.30 or less, and the fiber orientation strength of the non-coated surface is 1.00 or more and 1.50 or less, and the semipermeable membrane is at the interface of the semipermeable membrane and the semipermeable membrane support.
- the average area of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support when the is peeled off is 500 ⁇ m 2 or less, the semipermeable membrane residual rate is 2.5% or more and 5.0% or less, and the semipermeable membrane
- the semipermeable membrane For the semipermeable membrane support of Example 1-1 in which the Sb element elution amount of the support is less than 1.5 ⁇ g/g, the fiber orientation strength of the coated surface is 1.00 or more and 1.30 or less, and the non-coated surface The fiber orientation strength is 1.00 or more and 1.50 or less, and the amount of the semipermeable membrane remaining on the coated surface of the semipermeable membrane support when the semipermeable membrane is peeled off at the interface of the semipermeable membrane and the semipermeable membrane support.
- Example 1-20 having an average area of 500 ⁇ m 2 or less, a semipermeable membrane survival rate of 2.5% or more and 5.0% or less, and an Sb element elution amount of the semipermeable membrane support exceeding 1.5 ⁇ g/g Although the semipermeable membrane support of is at a usable level, it can be seen that the semipermeable membrane defects increase and the membrane peel strength decreases.
- the semipermeable membrane support of Comparative Example 1-6 In contrast to the semipermeable membrane support of Example 1-1, which was subjected to two-stage dispersion during the production of the base paper, the semipermeable membrane support of Comparative Example 1-6, which was not subjected to two-stage dispersion, had fibers on the surface coated with the semipermeable membrane.
- the average area of the semipermeable membrane remaining on the surface exceeded 500 ⁇ m 2 , and the residual rate of the semipermeable membrane was less than 2.5%, resulting in low membrane peel strength.
- Comparative Example 1-3 in which the temperature of the heat roll in the second stage was low, had a high survival rate of the semipermeable membrane. strike-through occurred, and the film peel strength was also low.
- Comparative Example 1-8 in which PET fibers 1-3 and 1-4 with a large amount of Sb element elution were blended and the combination of rolls in the first stage was changed to a metal roll-metal roll, the residual rate of the semipermeable membrane was 2. Since it is lower than 0.5%, it can be seen that the film peel strength is low.
- PET fiber 2-1 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 7.5 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.01 ⁇ g/g or less.
- PET fiber 2-2 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 7.5 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.12 ⁇ g/g.
- PET fiber 2-3 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 7.5 ⁇ m, a fiber length of 6 mm, and an Sb element elution amount of 10.3 ⁇ g/g.
- PET fiber 2-4 A drawn polyester fiber made of polyethylene terephthalate having a fiber diameter of 12.5 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 11.9 ⁇ g/g.
- PET fiber 2-5 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 11.8 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 2.3 ⁇ g/g.
- PET fiber 2-6 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 10.5 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.04 ⁇ g/g.
- PET fiber 2-7 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 11.8 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.01 ⁇ g/g or less.
- PET fiber 2-8 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 13.6 ⁇ m, a fiber length of 5 mm, and an Sb element elution amount of 0.01 ⁇ g/g or less.
- PET fiber 2-9 An unstretched polyester fiber made of polyethylene terephthalate having a fiber diameter of 13.6 ⁇ m, a fiber length of 10 mm, and an Sb element elution amount of 0.01 ⁇ g/g or less.
- the resulting base paper was subjected to heat calendering with a combination of metal roll (heat roll) and elastic roll, or with a heat calender with a combination of metal roll (heat roll) and metal roll (heat roll).
- Semipermeable membrane supports of Examples 2-1 to 2-16 and Comparative Examples 2-1 to 2-7 were obtained under the thermal calendering conditions described in .
- the surface (processed surface) of the base paper in contact with the metal roll (heat roll) is used as the coated surface
- the processed surface is , opposite to the first stage.
- the mesh surface is the surface formed by the mesh
- the inclined surface is the surface formed by the inclined wire.
- Basis Weight The basis weight was measured according to JIS P8124:2011.
- a semipermeable membrane support is cut to a width of 45 mm and a length of 60 mm to obtain a sample.
- a cellophane adhesive tape manufactured by Nichiban Co., Ltd., trade name: L-Pac (registered trademark) LP24
- L-Pac registered trademark
- a metal roll with a smooth surface (4 cm in diameter, 30 cm in length, and 3 kg in weight) is rolled three times over the sample to which the tape is attached, and the tape is evenly attached to the sample. Hold the portion of the tape that protrudes from the sample, slowly remove the tape from the sample, and observe the fibers stuck to the tape. Five samples were prepared and tested five times. The number of detached fibers present in the central portion (20 mm ⁇ 50 mm) of the tape peeled off from the sample was counted, and the average number of five tests was calculated.
- the Sb element elution amount was calculated by ⁇ Formula 1>.
- the lower limit of Sb quantification for the ICP-MS was 0.1 ppb, and the Sb content in the ultrapure water used for the measurement was below the lower limit of quantification.
- a DMF solution of polysulfone resin (concentration: 18%) was applied to the coated surface of the semipermeable membrane support to a thickness of 125 ⁇ m using a constant-speed coating device (trade name: TQC fully automatic film applicator, manufactured by Cortec Co., Ltd.) having a certain clearance. It was applied in thickness and allowed to phase separate in a coagulation bath to produce a porous polysulfone membrane.
- the separation membrane was cut to 14 cm x 19 cm and set in a flat membrane tester (trade name: SEPA CFII, Suez).
- An aqueous solution of 3.0% by mass of sodium chloride at 25° C. was passed through at a transmembrane pressure difference of 5.0 MPa between the feed side and the permeate side.
- the conductivity of the permeated water obtained by this operation was measured to calculate the salt blocking rate (%).
- the salt blocking rate was calculated from ⁇ Equation 2> using a calibration curve prepared from sodium chloride concentration and aqueous solution conductivity.
- Salt blocking rate (%) (1 - (sodium chloride concentration in permeate) / (sodium chloride concentration in feed)) x 100
- 0 to 1 points are at a very good level
- 2 to 3 points are at a good level
- 4 to 6 points are at a usable level
- 7 or more points are at an unusable level due to poor membrane performance.
- the semipermeable membrane supports of Examples 2-1 to 2-16 consisted of a wet-laid nonwoven fabric containing a main synthetic fiber and a binder synthetic fiber, had 30 or less detached fibers in a tape peeling test, and were confocal. Since the level difference of the core portion obtained by measuring the surface roughness of the coating surface on which the semipermeable membrane is provided is 14 ⁇ m or less with a laser microscope, the salt rejection rate is high, the defects of the semipermeable membrane are few, and the semipermeable membrane has few defects. was found to be difficult to reverse.
- the semipermeable membrane support of Example 2-5 in which the binder synthetic fiber content is 25%, is compared with the semipermeable membrane support of Example 2-1, in which the binder synthetic fiber content is 30%. , the salt rejection rate was low, and there were many defects of the semipermeable membrane, but it was at a usable level.
- Comparative Example 2-6 in which the PET fiber 2-1 of Example 2-5 was changed to PET fiber 2-3 with a large amount of Sb element elution, many detached fibers were found and the salt blocking rate was low.
- Comparative Example 2-7 has a large number of detached fibers and a core portion level difference Sk of more than 14 ⁇ m, so it can be seen that the salt blocking rate is low.
- the semipermeable membrane support of Example 2-4 which has an inclined wire surface as the coating surface, is at a usable level. It can be seen that the defects of the semipermeable membrane increase and the salt rejection decreases.
- the semipermeable membrane support of Comparative Example 2-3 which was not subjected to two-stage dispersion, had a core portion level difference Sk of 14 ⁇ m. , and it was a level that could not be used in the defect evaluation of the semipermeable membrane.
- the number of detached fibers in the tape peeling test is 30 or less, the core portion level difference Sk is 14 ⁇ m or less, the Sb element elution amount of the main synthetic fiber and the binder synthetic fiber is less than 5 ⁇ g/g, and the semipermeable membrane support Compared to the semipermeable membranes of Examples 2-1 and 2-7 having an Sb element elution amount of less than 1.5 ⁇ g/g, the number of detached fibers is 30 or less, and the core portion level difference Sk is 14 ⁇ m or less.
- the semipermeable membrane support of Example 2-16 in which the Sb element elution amount of the main synthetic fiber exceeds 5 ⁇ g/g and the Sb element elution amount of the semipermeable membrane support exceeds 1.5 ⁇ g/g, can be used. It can be seen that the defects of the semipermeable membrane increase and the salt blocking rate decreases, albeit at a level.
- the semipermeable membrane support of the present invention can be used in fields such as seawater desalination, water purifiers, food concentration, wastewater treatment, medical applications such as blood filtration, and ultrapure water production for cleaning semiconductors. can.
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Abstract
Description
(2)主体合成繊維とバインダー合成繊維とを含有する湿式不織布からなる半透膜支持体において、テープ剥離試験での離脱繊維が30本以下であり、かつ共焦点レーザー顕微鏡によって半透膜が設けられる塗布面の表面粗さを測定して得られるコア部のレベル差が14μm以下であることを特徴とする半透膜支持体。
(3)主体合成繊維又はバインダー合成繊維におけるアンチモン元素溶出量が5μg/g未満である(1)又は(2)に記載の半透膜支持体。
(4)半透膜支持体のアンチモン元素溶出量が1.5μg/g未満である(1)又は(2)に記載の半透膜支持体。
(5)(1)~(4)のいずれか記載の半透膜支持体を製造する半透膜支持体の製造方法において、バインダー合成繊維を分散した後に主体合成繊維を分散して得られる繊維分散液から湿式抄造法によって半透膜支持体を製造することを特徴とする半透膜支持体の製造方法。
本発明(1)の半透膜支持体は、主体合成繊維とバインダー合成繊維とを含有する湿式不織布からなる半透膜支持体において、半透膜が設けられる塗布面の繊維配向強度が1.00以上1.30以下であり、非塗布面の繊維配向強度が1.00以上1.50以下であり、かつ半透膜と半透膜支持体の界面で半透膜を剥離した際の半透膜支持体の塗布面に残存した半透膜の平均面積が500μm2以下であり、半透膜の残存率が2.5%以上5.0%以下であることを特徴とする。
(I)主体合成繊維の最適化(繊維径、繊維長、断面アスペクト比)
(II)二段階分散による繊維の分散性向上
(III)原紙の抄造条件の最適化
(IV)熱圧加工条件(熱ロール温度、加工速度)の調整
等が挙げられる。(III)として、より具体的には、
(III-1)湿式抄造時の濃度(抄水量)の調整
(III-2)抄造速度の調整
(III-3)スラリー流速とワイヤーの相対速度(J/W比)の調整
(III-4)ワイヤーパートでの脱水圧力の調整
(III-5)ドライヤーパートにおける張力バランス
を単独又は組み合わせて行うことで、制御することができる。中でも、(II)を行うことが好ましい。
本発明(2)の半透膜支持体は、主体合成繊維とバインダー合成繊維とを含有してなる湿式不織布からなり、テープ剥離試験において離脱繊維が30本以下であり、かつ共焦点レーザー顕微鏡によって半透膜が設けられる塗布面の表面粗さを測定して得られるコア部のレベル差が14μm以下であることを特徴とする。
(I)二段階分散による繊維の分散性の向上
(II)配合設計の最適化(繊維選定及びバインダー合成繊維の含有量)
(III)原紙の抄造条件の最適化
(IV)熱圧加工条件の調整
を単独又は組み合わせて行うことで、制御することができる。中でも、(I)を行うことが好ましい。
本発明(1)又は(2)において、主体合成繊維又はバインダー合成繊維におけるアンチモン(Sb)元素溶出量が5μg/g未満であることが好ましく、1μg/g未満であることがより好ましい。主体合成繊維又はバインダー合成繊維におけるSb元素溶出量が5μg/g未満であることによって、半透膜支持体の抄造時の繊維分散性が向上する。また、本発明(1)では、半透膜支持体から発生する離脱繊維を抑制でき、半透膜成膜後の膜剥離強度が向上するという効果が得られやすくなる。また、本発明(2)では、半透膜成膜後の塩阻止率が向上するという効果が得られやすくなる。Sb元素溶出量が5μg/g未満である主体合成繊維及びバインダー合成繊維は、重合触媒として、アンチモン化合物を使用しない又は使用量を少なくして、例えばチタン化合物、ゲルマニウム化合物、アルミニウム化合物等を重合触媒とした繊維として、市販されている。例えば、製造販売者としては、帝人フロンティア社、東レ社、南亜塑膠社、遠東新世紀社、Trevira社、Advansa社、Nirmal Fibres社等が挙げられる。湿式不織布に適した繊維長の短繊維として入手することも可能であるし、連続長繊維を入手して湿式不織布に適した繊維長にカットして使用することも可能である。
繊維又は半透膜支持体のSb元素溶出量(μg/g)=溶出液のSb元素含有量(μg/L)×溶出試験に使用した超純水の容積(L)/繊維又は半透膜支持体の質量(g)
≪主体合成繊維≫
PET繊維1-1:ポリエチレンテレフタレートからなる、繊維径7.5μm、繊維長5mm、Sb元素溶出量0.12μg/gの延伸ポリエステル繊維。
PET繊維1-5:ポリエチレンテレフタレートからなる、繊維径10.5μm、繊維長5mm、Sb元素溶出量0.04μg/gの未延伸ポリエステル繊維。
2m3の分散タンクに水を投入後、表1に示す繊維配合で、バインダー合成繊維を先に分散タンクに投入し3分間分散した後、主体合成繊維を分散タンクに投入し7分間混合分散(分散濃度2.0%)して、傾斜ワイヤー/円網複合抄紙機を用い、傾斜ワイヤー上で形成した湿紙と、円網ワイヤー上で形成した湿紙を積層させた後、表面温度130℃のヤンキードライヤーにて熱圧乾燥し、目標坪量70g/m2の原紙1-1~1-19、1-21及び1-22を得た。なお、傾斜ワイヤーと円網の繊維配合は同じである。
2m3の分散タンクに水を投入後、表1に示す繊維配合で、バインダー合成繊維と主体合成繊維を同時に分散タンクに投入し7分間混合分散(分散濃度2.0%)して、傾斜ワイヤー/円網複合抄紙機を用い、傾斜ワイヤー上で形成した湿紙と、円網ワイヤー上で形成した湿紙を積層させた後、表面温度130℃のヤンキードライヤーにて熱圧乾燥し、目標坪量70g/m2の原紙1-20を得た。なお、傾斜ワイヤーと円網の繊維配合は同じである。
得られた原紙に対して、金属ロール(熱ロール)-弾性ロールの組み合わせの熱カレンダー装置、又は、金属ロール(熱ロール)-金属ロール(熱ロール)の組み合わせの熱カレンダー装置にて、表2に記載する熱カレンダー条件で実施例1-1~1-20及び比較例1-1~1-8の半透膜支持体を得た。なお、最初に熱圧加工を行う第1ステージにて、原紙が金属ロール(熱ロール)に接する面(処理面)を塗布面とし、2回目に熱圧加工を行う第2ステージの処理面は、第1ステージと反対面とした。また、金属ロール(熱ロール)-金属ロール(熱ロール)の組み合わせで熱カレンダー処理をした半透膜支持体は、円網面を塗布面とした。
JIS P8124:2011に準拠して、坪量を測定した。
JIS P8118:2014に準拠して、厚さを測定し、密度を算出した。
半透膜支持体の半透膜が設けられる塗布面と反対の非塗布面を、走査電子顕微鏡(製品名:JSM-6610LV、日本電子社製)を用いて、倍率50倍で二次電子、加速電圧20kV、スポットサイズ30で撮影した。撮影の際、上下はMD方向(流れ方向)、左右はCD方向(幅方向)とした。1つの半透膜支持体の塗布面及び非塗布面につき測定点数10点の撮影を行った。
一定のクリアランスを有する定速塗布装置(商品名:TQC全自動フィルムアプリケーター、コーテック社製)を用いて、半透膜支持体の塗布面にポリスルホン樹脂のN,N-ジメチルホルムアミド(DMF)溶液(濃度:18%)を125μmの厚さで塗布し、凝固浴で相分離させ、多孔性ポリスルホン膜を作製した。この多孔性ポリスルホン膜に、m-フェニレンジアミン2質量%、ラウリル硫酸ナトリウム0.15質量%を含む水溶液Aを接触させた後、余分の水溶液Aを除去して、水溶液Aの被覆層を形成した。次いで、水溶液Aの被覆層表面にトリメシン酸クロライド0.3質量%を含有する溶液Bを接触させ、余分な溶液Bを排出した。その後、120℃で乾燥を行い、分離機能層を形成し、多孔性ポリスルホン膜と分離機能層からなる複合半透膜が半透膜支持体の塗布面に設けられた分離膜を得た。得られた分離膜を、以下の残存した半透膜の平均面積測定、半透膜の残存率測定、半透膜の欠点評価、膜剥離強度評価で使用した。
分離膜を風乾した後、MD方向を長辺として25mm×150mmの短冊状にカットし、分離膜面に両面テープ(商品名:ナイスタック(登録商標)NW-25、ニチバン社製)を貼り付け、膜剥離強度測定用試料を得た。定速緊張形引張試験機「シングルコラム型材料試験機、型番:STB-1225S」(エー・アンド・デイ社製)と用いて、チャック間距離20mmに設定し、チャックの移動速度50mm/minで、半透膜を半透膜支持体から剥離した。
半透膜を剥離した半透膜支持体の塗布面を、走査電子顕微鏡(製品名:JSM-6610LV、日本電子社製)を用いて、倍率100倍で二次電子、加速電圧20kV、スポットサイズ70で、硫黄(S)元素のマッピング分析(観察サイズ:1285μm×970μm)を行った。1つの半透膜支持体の塗布面につき、測定点数5点のマッピング分析を行った。
繊維又は半透膜支持体1.6gを、比抵抗18.2MΩ・cm、温度25℃の超純水0.20Lに24時間浸漬させ、溶出液30mLを採取し、これに硝酸(キシダ化学(株)、精密分析用、濃度60%)1μLを添加した後、誘導結合プラズマ質量分析装置(ICP-MS)(装置名:iCAP-Qc、Thermo Fisher Scientific社製)にて、溶出液に含まれるSb元素含有量を測定した上、検量線法により定量した。さらに、Sb元素溶出量を下式にて算出した。なお、該ICP-MSのSb定量下限値は0.1ppbであり、該測定に使用した超純水のSb含有量は定量下限値以下であった。
繊維又は半透膜支持体のSb元素溶出量(μg/g)=溶出液のSb元素含有量(μg/L)×溶出試験に使用した超純水の容積(L)/繊維又は半透膜支持体の質量(g)
分離膜を14cm×19cmに断裁し、平膜試験装置(商品名:SEPA CFII、Suez社)にセットした。200ppmの染料(ダイレクトブルー1、分子量:993)を含む水溶液を、25℃で膜の供給側と透過側の膜間差圧1.5MPaで通液した。その後、複合半透膜表面に堆積している染料を純水で洗い流し、分離膜を乾燥させ、染色部分(膜欠点部分)の数を測定した。
「2~3箇所」:良好なレベル。
「4~6箇所」:使用可能なレベル。
「7箇所以上」:膜性能が劣り、使用不可レベル。
一定のクリアランスを有する定速塗布装置(商品名:Automatic Film Applicator、安田精機製作所社製)を用いて、台紙の上に半透膜支持体をセットし、半透膜支持体の塗布面に黒色の油性インキを混合したポリスルホン樹脂のDMF溶液(濃度:18%)を塗布し、塗布後に半透膜支持体を貫通して台紙に写ったポリスルホン樹脂の量を目視で観察し、半透膜の裏抜け評価を行った。
「2」:小さな点状で、ごくわずかに裏抜けしている。良好なレベル。
「3」:小さな点状で、裏抜けしている。実用上、使用可能レベル。
「4」:大きな点状で、多く裏抜けしている。実用上、使用不可レベル。
分離膜を風乾した後、MD方向を長辺として25mm×150mmの短冊状にカットし、分離膜面に両面テープ(商品名:ナイスタック(登録商標)NW-25、ニチバン社製)を貼り付け、膜剥離強度測定用試料を得た。定速緊張形引張試験機「シングルコラム型材料試験機、型番:STB-1225S」(エー・アンド・デイ社製)と用いて、チャック間距離20mmに設定し、チャックの移動速度50mm/minとして、T型剥離試験を行い、試験開始から移動量20mm~80mmの剥離強度の平均を算出することにより、剥離強度を得た。各試料について、得られた10個の剥離強度の平均値を表3に示している。
≪主体合成繊維≫
PET繊維2-1:ポリエチレンテレフタレートからなる、繊維径7.5μm、繊維長5mm、Sb元素溶出量0.01μg/g以下の延伸ポリエステル繊維。
PET繊維2-5:ポリエチレンテレフタレートからなる、繊維径11.8μm、繊維長5mm、Sb元素溶出量2.3μg/gの未延伸ポリエステル繊維。
2m3の分散タンクに水を投入後、表4に示す繊維配合で、バインダー合成繊維を先に分散タンクに投入し3分間分散した後、主体合成繊維を分散タンクに投入し7分間混合分散(分散濃度2.0%)して、傾斜ワイヤー/円網複合抄紙機を用い、傾斜ワイヤー上で形成した湿紙と、円網上で形成した湿紙を積層させた後、表面温度130℃のヤンキードライヤーにて熱圧乾燥し、目標坪量70g/m2の原紙2-1~2-3及び2-5~2-16を得た。なお、傾斜ワイヤーと円網の繊維配合は、同じである。
2m3の分散タンクに水を投入後、表4に示す繊維配合で、バインダー合成繊維と主体合成繊維を同時に分散タンクに投入し7分間混合分散(分散濃度2.0%)して、傾斜ワイヤー/円網複合抄紙機を用い、傾斜ワイヤー上で形成した湿紙と、円網上で形成した湿紙を積層させた後、表面温度130℃のヤンキードライヤーにて熱圧乾燥し、目標坪量70g/m2の原紙2-4を得た。なお、傾斜ワイヤーと円網の繊維配合は同じである。
得られた原紙に対して、金属ロール(熱ロール)-弾性ロールの組み合わせの熱カレンダー装置、又は、金属ロール(熱ロール)-金属ロール(熱ロール)の組み合わせの熱カレンダー装置にて、表5に記載する熱カレンダー条件で実施例2-1~2-16及び比較例2-1~2-7の半透膜支持体を得た。なお、最初に熱圧加工を行う第1ステージにて、原紙が金属ロール(熱ロール)に接する面(処理面)を塗布面とし、2回目に熱圧加工を行う第2ステージの処理面は、第1ステージと反対面とした。表5において、円網面が円網で形成された面であり、傾斜面が傾斜ワイヤーで形成された面である。
JIS P8124:2011に準拠して、坪量を測定した。
JIS P8118:2014に準拠して測定した。
半透膜支持体を幅45mm×長さ60mmに断裁して試料とする。断裁した半透膜支持体の塗布面に幅24mm、長さ100mmに切ったセロハン粘着テープ(ニチバン社製、商品名:エルパック(登録商標)LP24)を試料の中央部に長さ方向にテープ両端がはみ出すようゴムマット上で貼り付ける。テープを貼った試料の上で表面が平滑な金属ロール(直径4cm、長さ30cm、重さ3kg)を3回転がし、テープを試料に均一に貼り付ける。貼り付けたテープの試料からはみ出した部分を持ち、試料からテープをゆっくりと剥がし、テープに貼り付いた繊維を観察する。試料を5枚準備して、5回のテストを行った。試料から剥がしたテープの中央部(20mm×50mm)に存在する、離脱繊維の本数を計測し、5回のテストの平均数を算出した。
半透膜支持体を幅45mm×長さ60mmに断裁して試料とする。共焦点レーザー顕微鏡(商品名:VK-X1050、キーエンス社製)を用い、観察倍率20倍に設定し、撮影サイズを縦3mm×横2mmに設定し、撮影を行う。計測領域は全領域を指定し、Skを測定する。
主体合成繊維、バインダー合成繊維又は半透膜支持体1.6gを、比抵抗18.2MΩ・cm、温度25℃の超純水0.20Lに24時間浸漬させて得られた溶出液30mLを採取し、これに硝酸(キシダ化学(株)、精密分析用、濃度60%)1μLを添加した後、誘導結合プラズマ質量分析装置(ICP-MS)(装置名:iCAP-Qc、Thermo Fisher Scientific社製)にて、溶出液に含まれるSb元素含有量を測定した上、検量線法により定量した。さらに、Sb元素溶出量を<式1>にて算出した。なお、該ICP-MSのSb定量下限値は0.1ppbであり、該測定に使用した超純水のSb含有量は定量下限値以下であった。
繊維又は半透膜支持体のSb元素溶出量(μg/g)=溶出液のSb元素含有量(μg/L)×溶出試験に使用した超純水の容積(L)/繊維又は半透膜支持体の質量(g)
一定のクリアランスを有する定速塗布装置(商品名:TQC全自動フィルムアプリケーター、コーテック社製)を用いて、半透膜支持体の塗布面にポリスルホン樹脂のDMF溶液(濃度:18%)を125μmの厚さで塗布し、凝固浴で相分離させ、多孔性ポリスルホン膜を作製した。この多孔性ポリスルホン膜に、m-フェニレンジアミン2質量%、ラウリル硫酸ナトリウム0.15質量%を含む水溶液Aを接触させた後、余分の水溶液Aを除去して、水溶液Aの被覆層を形成した。次いで、水溶液Aの被覆層表面にトリメシン酸クロライド0.3質量%を含有する溶液Bを接触させ、余分な溶液Bを排出した。その後、120℃で乾燥を行い、分離機能層を形成し、多孔性ポリスルホン膜と分離機能層からなる複合半透膜が半透膜支持体の塗布面に設けられた分離膜を得た。
塩阻止率(%)=(1-(透過液の塩化ナトリウム濃度)/(供給液の塩化ナトリウム濃度))×100
分離膜を14cm×19cmに断裁し、平膜試験装置(商品名:SEPA CFII、Suez社)にセットした。200ppmの染料(ダイレクトブルー1、分子量:993)を含む水溶液を、25℃で膜の供給側と透過側の膜間差圧1.5MPaで通液した。その後、複合半透膜表面に堆積している染料を純水で洗い流し、分離膜を乾燥させ、染色部分(膜欠点部分)の数を測定した。
一定のクリアランスを有する定速塗布装置(商品名:Automatic Film Applicator、安田精機製作所社製)を用いて、台紙の上に半透膜支持体をセットし、半透膜支持体の塗布面に黒色の油性インキを混合したポリスルホン樹脂のDMF溶液(濃度:18%)を塗布し、塗布後に半透膜支持体を貫通して台紙に写ったポリスルホン樹脂の量を目視で観察し、半透膜の裏抜け評価を行った。
2:小さな点状で、ごくわずかに裏抜けしている。良好なレベル。
3:小さな点状で、裏抜けしている。実用上、使用可能レベル。
4:大きな点状で、多く裏抜けしている。実用上、使用不可レベル。
Claims (5)
- 主体合成繊維とバインダー合成繊維とを含有する湿式不織布からなる半透膜支持体において、半透膜が設けられる塗布面の繊維配向強度が1.00以上1.30以下であり、非塗布面の繊維配向強度が1.00以上1.50以下であり、かつ半透膜と半透膜支持体の界面で半透膜を剥離した際の半透膜支持体の塗布面に残存した半透膜の平均面積が500μm2以下であり、半透膜の残存率が2.5%以上5.0%以下であることを特徴とする半透膜支持体。
- 主体合成繊維とバインダー合成繊維とを含有する湿式不織布からなる半透膜支持体において、テープ剥離試験での離脱繊維が30本以下であり、かつ共焦点レーザー顕微鏡によって半透膜が設けられる塗布面の表面粗さを測定して得られるコア部のレベル差が14μm以下であることを特徴とする半透膜支持体。
- 主体合成繊維又はバインダー合成繊維におけるアンチモン元素溶出量が5μg/g未満である請求項1又は2に記載の半透膜支持体。
- 半透膜支持体のアンチモン元素溶出量が1.5μg/g未満である請求項1又は2に記載の半透膜支持体。
- 請求項1~4のいずれか記載の半透膜支持体を製造する半透膜支持体の製造方法において、バインダー合成繊維を分散した後に主体合成繊維を分散して得られる繊維分散液から湿式抄造法によって半透膜支持体を製造することを特徴とする半透膜支持体の製造方法。
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WO2012090874A1 (ja) | 2010-12-27 | 2012-07-05 | 北越紀州製紙株式会社 | 半透膜支持体用湿式不織布、その製造方法及びその低密度欠点の確認方法 |
JP2012161725A (ja) * | 2011-02-04 | 2012-08-30 | Daio Paper Corp | 半透膜支持体、水処理用半透膜、および半透膜支持体の製造方法 |
JP2014128769A (ja) * | 2012-12-28 | 2014-07-10 | Daio Paper Corp | 半透膜支持体、半透膜支持体の製造方法及び半透膜 |
WO2014192883A1 (ja) | 2013-05-30 | 2014-12-04 | 東レ株式会社 | 複合半透膜 |
JP2016159197A (ja) | 2015-02-27 | 2016-09-05 | 三菱製紙株式会社 | 膜分離活性汚泥処理用半透膜用支持体 |
JP2017170293A (ja) * | 2016-03-22 | 2017-09-28 | 三菱製紙株式会社 | 半透膜支持体 |
JP2018153758A (ja) | 2017-03-17 | 2018-10-04 | 帝人フロンティア株式会社 | 分離膜用不織布 |
JP2019118907A (ja) * | 2018-01-11 | 2019-07-22 | 三菱製紙株式会社 | 半透膜用支持体 |
JP2020163321A (ja) * | 2019-03-29 | 2020-10-08 | 三菱製紙株式会社 | 膜分離活性汚泥処理用半透膜用支持体及び濾過膜 |
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