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WO2025250460A1 - Films polymères poreux de polyuréthane et de polyurée - Google Patents

Films polymères poreux de polyuréthane et de polyurée

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Publication number
WO2025250460A1
WO2025250460A1 PCT/US2025/030759 US2025030759W WO2025250460A1 WO 2025250460 A1 WO2025250460 A1 WO 2025250460A1 US 2025030759 W US2025030759 W US 2025030759W WO 2025250460 A1 WO2025250460 A1 WO 2025250460A1
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WIPO (PCT)
Prior art keywords
polymer
polymer film
film
mol
cyclic
Prior art date
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Pending
Application number
PCT/US2025/030759
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English (en)
Inventor
Gabor Erdodi
Priyesh A. WAGH
Kurt Schroeder
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Lubrizol Corp
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Lubrizol Corp
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Publication of WO2025250460A1 publication Critical patent/WO2025250460A1/fr
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Classifications

    • 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
    • B01D71/54—Polyureas; Polyurethanes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • 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
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/219—Specific solvent system
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/14—Membrane materials having negatively charged functional groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/18—Membrane materials having mixed charged functional groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/20—Specific permeability or cut-off range
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/24—Mechanical properties, e.g. strength

Definitions

  • the disclosed technology relates to porous polymer films made from polyurethane or polyurea polymer compositions.
  • Porous polymer films for separation applications have traditionally been manufactured using a small class of polymers including; polyethersulfone, polysulfone, PVDF, Teflon, Cellulose Acetate and PVC-based. These polymers have been the workhorse for preparing polymer films for decades with few new polymers having been introduced in recent years.
  • Fluorine containing polymers continue to be under scrutiny from an environmental standpoint.
  • Polyvinylchloride as a base polymer is difficult to modify (both compositionally and via post treatment).
  • Polyurethanes present a tremendous amount of flexibility in their design. They offer the potential to be synthesized to tailor both physical properties, functionality and chemical stability.
  • Polyurethanes should be amenable to the NIPS process and also present the possibility to be synthesized and/or formulated with “green solvent” alternatives to the commonly used environmentally unfriendly solvents such as NMP, DMAC, and DMF.
  • thermoplastic polyurethanes are believed to be inferior in mechanical properties for separations applications as the integrity of the pores can be compromised under high pressures used in most membrane applications.
  • the disclosed technology solves the problem of reduced integrity in polyurethane and polyurea polymer films by preparing the polymer compositions with a high degree of hard segments containing cyclic or polycyclic hydrocarbyl moi eties.
  • the technology provides a porous polymer film prepared from a polyurethane or polyurea (collectively, “PU”) polymer composition.
  • the porous polymer films can contain from at least about 80 weight percent of at least one PU polymer.
  • the PU polymer can include at least 75 wt% hard segments derived from at least one diisocyanate in combination with at least one chain extending compound. In embodiments, at least 75% of the combination of the at least one diisocyanate and at least one chain extending compound in the hard segment will include cyclic or polycyclic hydrocarbyl moieties.
  • the PU composition can prepare semipermeable polymer films.
  • the PU polymer composition in the polymer film can be further functionalized with one or more anionic moieties.
  • the polymer films prepared from the PU polymer composition can include a plurality of pores having a pore size of at least 1 nm in diameter.
  • the porous polymer film can be prepared by dissolving in an aprotic organic solvent in an amount of 5 weight percent to 40 weight percent and then precipitating the PU polymer to form a porous film.
  • the PU polymer composition can be precipitated onto a permanent substrate selected from polyester, polypropylene, polyolefins.
  • the porous polymer film can be cast onto a release belt such that the film includes no permanent substrate.
  • the porous polymer film can be employed to filter or separate organic or biologic matter carried in an aqueous effluent.
  • the process can include flowing a filterable fluid under pressure through the porous polymer film while discharging an unfiltered part of the fluid from an outlet.
  • the technology includes a porous polymer film.
  • Polymer films are generally prepared by precipitating a polymer composition.
  • the polymer composition for the polymer film of the present invention includes a polyurethane or polyurea polymer.
  • Polyurethane and polyurea (collectively, PU) polymers according to the technology are obtained by the reaction of a polyisocyanate, a chain extender component, and optionally a polyol intermediate. In this reaction, a catalyst is used if needed.
  • the polymer composition for the porous polymer film can include at least about 80 wt.%, and in some embodiments 85 wt.%, or 90 wt.%, or even 95 wt.% of at least one PU polymer having a high degree of hard segments.
  • Hard segments refer to polymeric moieties in the PU derived from the reaction of the diisocyanate and the chain extending compound. At least 75 wt% of the PU polymer in the porous polymer film can be hard segments. In some embodiments, at least 80 wt%, or 85 wt% of the PU polymer in the porous polymer film can be hard segments. In embodiments, at least 90 wt%, or 95 wt% of the PU polymer in the porous polymer film can be hard segments.
  • the PU polymers will include cyclic or polycyclic hydrocarbyl moieties. At least 75% of the hard segments can include cyclic or polycyclic hydrocarbyl moieties. In some embodiments, at least 80%, or 85% of the hard segments can include cyclic or polycyclic hydrocarbyl moieties. In embodiments, at least 90%, or 95% of the hard segments can include cyclic or polycyclic hydrocarbyl moieties.
  • the polyisocyanate component can include one or more diisocyanates, which may be selected from cyclic or polycyclic diisocyanates, or acyclic diisocyanates or combinations thereof.
  • cyclic or polycyclic polyisocyanates include, but are not limited to aromatic diisocyanates such as 4,4'-methylenebis(phenyl isocyanate) (MDI), m-xylene diisocyanate (XDI), phenylene- 1,4-diisocyanate, 3,3’ -di - methyl-4,4’-biphenylene diisocyanate (TODI), 1,5 -naphthalene diisocyanate (ND I), and toluene diisocyanate (TDI).
  • MDI 4,4'-methylenebis(phenyl isocyanate)
  • XDI m-xylene diisocyanate
  • TODI phenylene- 1,4-diisocyanate
  • ND I 1,5 -naphthalene diisocyanate
  • TDI toluene diisocyanate
  • cyclic or polycyclic polyisocyanates include, but are not limited to isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'- diisocyanate (H12MDI), 1,4-cyclohexylene diisocyanate (CHDI).
  • IPDI isophorone diisocyanate
  • H12MDI dicyclohexylmethane-4,4'- diisocyanate
  • CHDI 1,4-cyclohexylene diisocyanate
  • Acyclic diisocyanates may also be employed in the PU polymer compositions, so long as the total content of cyclic or polycyclic moieties of the polymer is within the desired ranges taught herein.
  • Example acyclic polyisocyanates include, but are not limited to, 1,6-hexamethylene diisocyanate (HD I), decane-1, 10- diisocyanate, lysine diisocyanate (LDI), 1,4-butane diisocyanate (BDI), and pentamethylene diisocyanate (PDI).
  • Isocyanates used to make the PU films useful in the present invention will depend on the desired properties of the final polymer film structure as will be appreciated by those skilled in the art.
  • the PU polymers useful in the present invention will also include a chain extender component.
  • Chain extending compounds are low molecular weight alcohols, in the case of polyurethanes, or amines, in the case of polyureas.
  • Low molecular weight in the context of chain extending compounds means a number average molecular weight of less than 500 g/mol, or even less than 300 g/mol.
  • Chain extenders include diols, diamines, and combinations thereof.
  • Suitable cyclic or polycyclic polyol chain extenders include relatively small polyhydroxy compounds, for example lower aliphatic or short chain glycols having from 2 to 20, or 2 to 12, or 2 to 10 carbon atoms.
  • Other examples include 1,4-cyclohexanedimethanol (CHDM), 2, 2-bis[4-(2-hydroxy ethoxy) phenyl]pro- pane (HEPP), hydroxyethyl resorcinol (HER), hydrogenated bisphenol (HBPA), and 1,4-phenylenediboronic acid (PDBA).
  • CHDM 1,4-cyclohexanedimethanol
  • HEPP 2, 2-bis[4-(2-hydroxy ethoxy) phenyl]pro- pane
  • HER hydroxyethyl resorcinol
  • HBPA hydrogenated bisphenol
  • PDBA 1,4-phenylenediboronic acid
  • Acyclic polyol chain extenders may also be employed in the PU polymer compositions, so long as the total content of cyclic or polycyclic moi eties of the polymer is within the desired ranges taught herein.
  • Suitable examples include ethylene glycol, di ethylene glycol, propylene glycol, dipropylene glycol, 1,4-bu- tanediol (BDO), /1,6-hexanediol (HDO), 1,3 -butanediol, 1,5-pentanediol, neopentylglycol, dodecanediol, hexamethylenediol, heptanediol, nonanediol, dodecanediol, 3 -methyl- 1 , 5 -pentanediol,
  • Suitable cyclic or polycyclic amine chain extenders include, for example, isophorone diamine (IPDA), 4,4'-Methylenebis(2-methylcyclohexylamine) (MHMDA), and 4,4’ -methylene bis(N-secbutylcylcohexanamine).
  • Acyclic amine chain extenders may also be employed in the PU polymer compositions, so long as the total content of cyclic or polycyclic moi eties of the polymer is within the desired ranges taught herein. Examples include ethylenediamine, butanediamine, hexamethylenediamine, and the like.
  • the PU polymers useful in the present invention may also optionally include a polyol intermediate component so long as the total amount of hard segments in the PU polymer composition meet the ranges taught herein.
  • Polyol intermediates include polyether polyols, polyester polyols, polycarbonate polyols, polysiloxane polyols, polyamide polyols, and combinations thereof.
  • the PU polymer compositions can have number average molecular weights of from about 5,000 to about 500,000 g/mol, or in some embodiments, from about 6000 to about 475,000 g/mol, or from about 7000 to about 450,000 g/mol, or even from about 8000 to about 425,000 g/mol, or from about 9000 to about 400,000 g/mol or from about 10,000 to about 400,000 g/mol.
  • the PU polymer composition includes hard segments containing cyclic or polycyclic diisocyanate. In further embodiments, the PU polymer composition includes hard segments containing cyclic or polycyclic diisocyanate as well as cyclic or polycyclic chain extender.
  • the PU polymer composition can include, for example, hard segments containing cyclic or polycyclic diisocyanate cyclic or polycyclic polyol.
  • the PU polymer composition can also include, for example, hard segments containing cyclic or polycyclic diisocyanate cyclic or polycyclic amine. In embodiments, the PU polymer composition can include hard segments containing cyclic or polycyclic chain extender.
  • additives include but are not limited to antioxidants, such as phenolic types, organic phosphites, phosphines and phosphonites, hindered amines, organic amines, organo sulfur compounds, lactones and hydroxylamine compounds, biocides, fungicides, antimicrobial agents, compatibilizers, electro-dissipative or anti-static additives, fillers and reinforcing agents, such as titanium dixide, alumina, clay and carbon black, flame retardants, such as phosphates, halogenated materials, and metal salts of alkyl benzenesulfonates, impact modifiers, such as methacrylate-butadiene-styrene (“MBS”) and methylmethacrylate butylacrylate (“MBA”), mold release agents such as waxes, fats and oils, pigment
  • additives can be incorporated into the components of, or into the reaction mixture for, the preparation of the PU polymer composition resin, or after making the PU polymer composition resin. In another process, all the materials can be mixed with the PU polymer composition resin and then melted or they can be incorporated directly into the melt of the PU polymer composition resin. Additives may be selected by those of ordinary skill in the art based on the desired properties to be imparted to the polymer film of the present invention.
  • the PU polymer used to make the PU polymer composition film for the polymer film includes one or more additives selected from antioxidants, biocides, fungicides, antimicrobial agents, compatibilizers, electro-dissipative or anti-static additives, fillers and reinforcing agents, flame retardants, impact modifiers, mold release agents such as waxes, fats and oils, pigments and colorants, plasticizers, polymers, rheology modifiers, slip additives, and UV stabilizers.
  • the PU polymer of the present invention includes UV stabilizers, in particular, one or more of hindered amine light stabilizers (HALS) and/or UV light absorber (UVA) types.
  • HALS hindered amine light stabilizers
  • UVA UV light absorber
  • crosslinking may be accomplished during the formation of the prepolymers, during the dispersing stage or later, such as before or after casting a film.
  • Compounds having at least one crosslinkable functional group may be used to crosslink the PU polymers. Such compounds include those having carboxylic, carbonyl, amine, hydroxyl, acetoacetoxy, vinyl, allyl, acrylic, methacrylic, tert-carbon and hydrazide groups, and the like, and mixtures of such groups.
  • crosslinkers can include any polyene, e.g. decadiene or trivinyl cyclohexane; acrylamides, such as methylene bis acrylamide; polyfunctional acrylates, such as trimethylol propane triacrylate; or polyfunctional vinylidene monomer containing at least 2 terminal CH2 ⁇ groups, including for example, butadiene, isoprene, divinyl benzene, divinyl naphthlene, allyl acrylates and the like.
  • polyene e.g. decadiene or trivinyl cyclohexane
  • acrylamides such as methylene bis acrylamide
  • polyfunctional acrylates such as trimethylol propane triacrylate
  • polyfunctional vinylidene monomer containing at least 2 terminal CH2 ⁇ groups including for example, butadiene, isoprene, divinyl benzene, divinyl naphthlene, allyl acrylates and the like.
  • cross-linking monomers include for example, diallyl esters, dimethallyl ethers, allyl or methallyl acrylates and acrylamides, tetraallyl tin, tetravinyl silane, alkoxysilanes such as methylti- methoxysilane, tetramethoxy silane, ethyl polysilicate and the like, polyalkenyl methanes, diacrylates, and dimethacrylates, divinyl compounds such as divinyl benzene, polyallyl phosphate, diallyloxy compounds and phosphite esters and the like.
  • suitable compounds providing crosslinkability include thioglycolic acid, 2,6-dihydroxybenzoic acid, and the like, and mixtures thereof.
  • the typical amount of such optional compound is up to about 1 milliequivalent, preferably from about 0.05 to about 0.5 milliequivalent, and more preferably from about 0.1 to about 0.3 milliequivalent per gram of final PU polymer on a dry weight basis.
  • the preferred monomers for incorporation into the isocyanate-terminated prepolymer are hydroxy-carboxylic acids having the general formula (HO)xQ(COOH)y, wherein Q is a straight or branched hydrocarbon radical having 1 to 12 carbon atoms, and x and y are 1 to 3.
  • hydroxycarboxylic acids include citric acid, dimethylolpropanoic acid (DMPA), dimethylol butanoic acid (DMBA), glycolic acid, lactic acid, malic acid, dihydroxymalic acid, tartaric acid, hydroxypivalic acid, and the like, and mixtures thereof.
  • Dihydroxy-carboxylic acids are more preferred with dimethylolpropanoic acid (DMPA) being most preferred.
  • Suitable compounds providing crosslinkability include thioglycolic acid, 2,6-dihydroxybenzoic acid, dihydroxyacetone, trimethylol-propane monoacrylate, pentacrythritol triallyl ether, sulfonic acid, phosphonic acid and even zwitterions (sulfo-betaine or carboxy betaine) and the like, and mixtures thereof.
  • the PU polymer composition may also be functionalized with one or more anionic moieties.
  • the anionic moieties may be, for example, acid diols or acid diamines having a molecular weight of less than 500 g/mol, such as, hydroxy or amine-carboxylic acid having the general formula (A)xQ(COOH)y, wherein A is a hydroxyl group or amine group, Q is a straight, branched, or cyclic hydrocarbon radical having 1 to 12 carbon atoms, and x and y are 1 to 3.
  • hydroxy-carboxylic acids examples include citric acid, dimethylolpropionic acid (DMPA), dimethylol butanoic acid (DMBA), glycolic acid, lactic acid, malic acid, dihydroxymalic acid, tartaric acid, hydroxypivalic acid, thioglycolic acid, 2,6- dihydroxybenzoic acid and the like, and mixtures thereof.
  • aminecarboxylic acids include diaminobutyric acid (DABA), 2,4-diaminobenzoic acid, lysine, and ornithine.
  • the anionic moieties may also be, for example, sulfonic acid diols or acid diamines having a molecular weight of less than 500 g/mol, such as 2,5-diaminobenzenesulfonic acid, and the like.
  • a counterion such as any of the organic bases, for example tri ethylamine, dimethylethanolamine, triethanolamine, tris(hydroxymethyl)aminomethane, may be employed to neutralize the acid groups in the casting solution to allow preparation of the polymer films.
  • organic bases for example tri ethylamine, dimethylethanolamine, triethanolamine, tris(hydroxymethyl)aminomethane
  • the content of anionic moieties in the PU polymer can be represented as an acid number in terms of mg of KOH per gram of PU polymer needed to fully neutralize the acid functionality.
  • the PU polymer can contain a sufficient number of anionic moiety to have an acid number of 20 or less, or even 19 or less or 18 or less. In embodiments, the PU polymer can contain a sufficient number of anionic moiety to have an acid number of between 1 and 20, or between 2 and 19, or between 3 and 18. In some embodiments, the PU polymer can contain a sufficient number of anionic moiety to have an acid number of between 4 or 5 and 17, or even 6 and 17.
  • the preparation of the various PU polymer composition may be accomplished in accordance with conventional procedures and methods and, since as noted above, generally any type of PU polymer composition can be utilized, the various amounts of specific components thereof, the various reactant ratios, processing temperatures, catalysts in the amount thereof, polymerizing equipment such as the various types of extruders, and the like, are all generally conventional, and well as known to the art and to the literature.
  • the process is a so-called “one-shot” process where all reactants are added to an extruder reactor and reacted.
  • the equivalent weight amount of the diisocyanate to the total equivalent weight amount of the chain extender and optional polyol intermediate can be from about 0.95 to about 1.10, or from about 0.96 to about 1.02, and even from about 0.97 to about 1.005.
  • Reaction temperatures utilizing a urethane catalyst can be from about 50 to about 150 °C, and in another embodiment from 75 to 125 °C.
  • the PU can also be prepared utilizing a pre-polymer process.
  • the optional polyol intermediates are reacted with generally an equivalent excess of one or more diisocyanates to form a pre-polymer solution having free or unreacted diisocyanate therein.
  • the reaction is generally carried out at temperatures of from about 80 to about 220 °C, or from about 150 to about 200 °C in the presence of a suitable catalyst.
  • a chain extender as noted above, is added in an equivalent amount generally equal to the isocyanate end groups as well as to any free or unreacted diisocyanate compounds.
  • the overall equivalent ratio of the total diisocyanate to the total equivalent of the chain extender and optional polyol intermediate is thus from about 0.95 to about 1.10, or from about 0.96 to about 1.02 and even from about 0.97 to about 1.05.
  • the chain extension reaction temperature is generally from about 50 to about 150 °C or from about 75 to about 125 °C.
  • the pre-polymer route can be carried out in any conventional device including an extruder.
  • the optional polyol intermediates are reacted with an equivalent excess of a diisocyanate in a first portion of the extruder to form a pre-polymer solution and subsequently the chain extender is added at a downstream portion and reacted with the pre-polymer solution.
  • Any conventional extruder can be utilized, including extruders equipped with barrier screws having a length to diameter ratio of at least 20 and in some embodiments at least 25.
  • the PU polymer can be prepared in a solvent, and the resulting polymer solution can be employed as the casting solution for the porous polymer film.
  • the polymer can be prepared at concentrations of from 5wt% to 40wt% of the expected polymer composition in a solvent, or from 7.5wt% to 35wt% of the polymer composition in a solvent or even from from 10wt% to 30wt% of the polymer composition in a solvent. This has the advantage that the PU polymer does not need to be redissolved to cast the polymer film.
  • Preparation of a porous polymer film for separation or purification using the PU polymer composition can be accomplished by dissolving from 5wt% to 40wt% of the polymer composition in a solvent to prepare a casting solution, or from 7.5wt% to 35wt% of the polymer composition in a solvent or even from from 10wt% to 30wt% of the polymer composition in a solvent. Dissolution of the polymer composition can be accomplished with the aid of heat.
  • Suitable solvents for the casting solution are not particularly limited and can include, for example, dimethyltryptamine (DMT), DMAC, dimethyl sulfoxide (DMSO), sulfolane, glycol ethers, and “green” solvents.
  • Other alternative solvents can include, for example, N-methyl pyrrolidone (NMP), N-ethyl pyrrolidone (NEP), N-butyl pyrrolidone, dimethyl formamide (DMF), methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, tetrahydrofuran (THF), and acetone.
  • NMP N-methyl pyrrolidone
  • NEP N-ethyl pyrrolidone
  • N-butyl pyrrolidone dimethyl formamide
  • MEK methyl ethyl ketone
  • MIBK methyl isobutyl ketone
  • Another suitable solvents for preparing the casting solution can include, for example, amides represented by Formula I:
  • R2, R3, and R4 are independently H, or C n H(2n+i);
  • - Aik is a CnEEn alkylene group, linear or branched; and n is an integer from 1 to 10.
  • X is O and R3 is CnH(2n+l).
  • the alkylene group of Formula I can contain only one or two carbon atoms, in which case the mild solvents can be represented, respectively, by Formula II or Formula III: Formula II
  • Example mild solvents include 3-methoxy-N,N-dimethylpropanamide and 3 -butoxy -N,N-dimethylpropanamide.
  • the solvent for the blend can be a mixture of these solvents, and may also include one or more other liquids that are non-solvents for the PU polymer composition.
  • the polymers can be mixed with portions of the solvent separately and then mixed, they can be mixed with the solvent sequentially, or the polymers can be mixed with the solvent simultaneously. It may be desirable to heat the solvent- polymer mixture while mixing or agitating to facilitate complete dissolution of the polymer composition.
  • the solvent may be present in the casting solution at a concentration of from about 30 to about 90 wt%, or from about 30 to about 70 wt%, or even from about 35 to about 65 wt% or about 40 to about 60 wt%.
  • the casting solution provided herein can also contain pore forming agent, although a pore forming agent may be absent.
  • a pore-forming agent is a substance that is soluble in the blend solvent (described below) and that may or may not be soluble in the coagulation solvent (described below).
  • the presence of a pore-forming agent can provide for greater control over the size and distribution of pores in the porous polymer film that is formed from the coagulation in the coagulation bath.
  • the pore-forming agent in its pure state at room temperature can be a liquid, but is often a water-soluble solid. Examples of pore-forming agents suitable for the casting solution/porous polymer film include salts and phenols.
  • salts of alkali metals, alkaline earth metals, transition metals or ammonium in the form of halides or carbonates can be used as pore-forming agents.
  • Specific examples include ammonium chloride, calcium chloride, magnesium chloride, lithium chloride, sodium chloride, zinc chloride, calcium carbonate, magnesium carbonate, sodium carbonate, and sodium bicarbonate.
  • Sodium citrate can also be used as a pore forming agent.
  • phenols include phenol, ethylphenol, catechol, resorcinol, hydroquinone and methoxyphenol.
  • Non-solvent liquids include polymers such as poly(vinyl alcohol), poly(vinyl pyrrolidone), glycols, such as polyethylene glycol, ethyleneoxide copolymers, and hydroxyalkylcellulose polymers.
  • polymers such as poly(vinyl alcohol), poly(vinyl pyrrolidone), glycols, such as polyethylene glycol, ethyleneoxide copolymers, and hydroxyalkylcellulose polymers.
  • the molecular weight of the pore forming agent in some embodiments, can have an effect on the size of the pores formed in the porous polymer film. Normally the pore size of a porous polymer film increases with increasing molecular weight of the pore former, but this is not always a hard rule on this. Sometimes, pore size/pore distribution reaches an optimum value and it does not increase with an increase in pore former molecular weight. The effect of molecular weight varies from pore former to pore former.
  • the pore forming agent can be a poly(vinyl pyrrolidone) having a molecular weight of from about 8000 to about 150,000.
  • the pore former may be a poly(vinyl pyrrolidone) having a molecular weight of from about 40,000 to about 150,000.
  • the poly(vinyl pyrrolidone) pore forming agent may have a molecular weight of from about 200 to about 40,000 g/mol.
  • the pore forming agent can be a poly(ethylene glycol)- block-poly(propylene glycol)-block-poly(ethylene glycol) copolymer having a molecular weight of from about 1000 to about 6000 g/mol.
  • the pore former may be a poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) copolymer having a molecular weight of from about 3000 to about 6000 g/mol.
  • the poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(eth- ylene glycol) copolymer pore forming agent may have a molecular weight of from about 2000 to about 4000 g/mol. In other instances, such as for preparing a nan- ofiltration porous polymer film, the poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) copolymer pore forming agent may have a molecular weight of from about 1000 to about 2000 g/mol.
  • the pore forming agent can be a polyethylene glycol having a number average molecular weight of from about 200 to about 20,000 g/mol.
  • the pore former may be a polyethylene glycol having a number average molecular weight of from about 8000 to about 20,000 g/mol.
  • the polyethylene glycol pore forming agent may have a molecular weight of from about 200 to about 10,000 g/mol.
  • the pore forming agent may be absent.
  • the pore forming agent can also be present in the casting solution at a concentration of from about 0.1 to about 20 wt%, or from about 0.2 to about 18 wt%, or from about 0.4 to about 16 wt%, or even from about 0.5 to about 15 wt% or about 0.5 to about 10 wt%.
  • the pore forming agent may be present in the casting solution at a concentration of from about 0.1 to about 5 wt%, or from about 0.2 to about 2.5wt%, or even from about 0.25 to about 1 wt%.
  • the casting solution can also include processing aids, such as surfactants, drying agents, co-solvents, such as polar aprotic solvents, or any combination thereof.
  • processing aids can be employed to modify surface properties, such as hydrophobicity, or further increase performance, such as compressibility and tensile strength, of a porous polymer film prepared from the casting solution, for example, to improve fouling resistance.
  • the processing aids collectively, can be in the casting solution at a concentration of about 0.1 to about 10 wt.%, or from about 0.5 to about 8 wt%, or even from about 1 to about 6 wt%.
  • Exemplary processing aids include phosphoramides, dialkyl sulfoxides, metal chelate additives containing a bidentate ligand and a metal atom or metal ion, e.g., acetylacetonate (acac) or fluorinated acetylacetonate, beta-diketonates or fluorinated beta-diketonates, zeolites, fullerenes, carbon nanotubes, and inorganic mineral compounds.
  • metal chelate additives containing a bidentate ligand and a metal atom or metal ion e.g., acetylacetonate (acac) or fluorinated acetylacetonate, beta-diketonates or fluorinated beta-diketonates, zeolites, fullerenes, carbon nanotubes, and inorganic mineral compounds.
  • the surfactant(s) can be selected from among nonionic, cationic, anionic, and zwitterionic surfactants depending on the chemistry of the other additives. For example, a cationic surfactant would not be selected when anionic additives are being used.
  • the amount of surfactant can be from about 0.005 wt % to about 0.5 wt %, or from about 0.01 wt % to about 0.25 wt %, or from about 0.05% to about 0.25%.
  • one or more drying agents can be included in the casting solution.
  • Porous polymer films are often dried at either ambient or elevated temperatures to maintain performance during storage and transportation. Storage and shipping of porous polymer film in a wet state presents challenges as residual water in the pores of porous polymer films provides an opportunity for microbes to flourish. Furthermore, the pore size and morphology of porous polymer films stored at or below the freezing temperature of water can be damaged. Drying agents can have both antimicrobial effects and also allow transportation at significantly colder temperatures than in a wet state.
  • Drying agents can include, for example, hydrophobic organic compounds, such as a hydrocarbon or an ether, glycerin, citric acid, glycols, glucose, sucrose, triethylammonium camphorsulfonate, tri ethyl ammonium benzenesulfonate, triethylammonium toluenesulfonate, triethylammonium methane sulfonate, ammonium camphor sulfonate, and ammonium benzene sulfonate, and those described in U.S. Pat. Nos. 4,855,048; 4,948,507; 4,983,291; and 5,658,460.
  • hydrophobic organic compounds such as a hydrocarbon or an ether, glycerin, citric acid, glycols, glucose, sucrose, triethylammonium camphorsulfonate, tri ethyl ammonium benzenesulfonate, tri
  • the amount of drying agent can be from about 2 wt % to about 10 wt %, or from about 3 wt % to about 5 wt %.
  • Preparation of the porous polymer film also requires one or more nonsolvent quenching solutions.
  • the quenching solution can be water-based and can include various additives including, for example, alcohols (ethanol, isopropanol), humectants (glycerol and glycols), casting solution solvents and water soluble surfactants.
  • the temperature of the quench tank can be manipulated in order to tune the morphology of the porous polymer film. In one embodiment, the initial quench tank contains mostly water.
  • the initial quench tank can be followed by additional water tanks in order to facilitate removal of the solvent(s) from the casted porous polymer film.
  • the final quench tank can contain a treatment fluid that is a humectant or mixture of humectant and water. Examples include a mixture of between 15-50% by weight of a high boiling organic solvent and water. Examples of treatment fluids include water and comprise high boiling organic solvents such as glycerol, propylene glycol, ethylene glycol, and other polyhydric alcohols.
  • the humectant often aids in drying of the porous polymer film at elevated temperatures and facilitates storage of the porous polymer film for subsequent use while minimizing any loss in flux or solute retention in the target application.
  • a preservative can be added to the final water rinse tank or treatment fluid tank if desired.
  • Preservatives can be added to inhibit undesired biological growth in the porous polymer film. Any of the well known preservatives can be used including, for example, sodium metabisulfite, substituted or un-substituted isothiazolines, etc.
  • porous polymer films may be in a tubular, hollow fiber, spiral wound, or flat sheet structure, however as used herein the term “film” is used to refer specifically to a porous flat sheet having a selectively permeable barrier or partition.
  • Flat sheet means the film has a first surface and a second surface opposite to each other, wherein the first surface corresponds to an effluent side and the second surface corresponds to a filtrate side.
  • Such films have a number of uses, and in particular for filtration, where permeability is based on the film being porous.
  • the porous polymer film may be cast from the casting solution described above to obtain a porous polymer film having pores suitable for use in microfiltration, ultrafiltration, or nano-filtration. That is to say that the porous polymer film may have pores suitable for microfiltration ranging in size from about 0.1 to about 10 pm, or about 0.5 to 1 pm; or pores suitable for ultrafiltration ranging in size from about 0.005 to 0.1 pm, or about 0.01 to 0.05 pm; or pores suitable for nano-filtration ranging in size from about 0.00005 to 0.01 pm, or about 0.0001 to 0.005 pm.
  • the pores in the film may be distributed through the film symmetrically, meaning the distribution of pores within the film are on average of about the same size and spacing, or asymmetrically.
  • the pore structure in an asymmetric film exhibits a gradient where the size of the pores gradually changes from large pores at the filtrate side of the film to small pores at the effluent side. The smaller the pores, the more the effluent side layer appears as a “skin” layer on the effluent side of the film. While some asymmetric films may have a skin that is integral with the film, other asymmetric films have a skin that is coated onto a substrate such as polyester, polypropylene, polyolefin substrates, to form the film.
  • the asymmetric film may have a 0.01-5 micron layer over a more porous 100-300 micron thick layer.
  • the pores in the asymmetric film do not grade out small enough to form a skin layer, in which case the film does not contain a skin layer.
  • the film provided herein may have an asymmetric structure without a skin layer.
  • the film may also have an asymmetric structure with a skin layer. Where the film includes a skin layer, the skin layer may be integral to the film or coated onto the film.
  • the casting solution is prepared, as described above, by dissolving the ingredients into the casting solution solvents.
  • the casting solution can be prepared at elevated temperature, such as 50 to 60°C to aid in quicker dissolution.
  • After mixing the casting solution is degassed, for example, by application of a vacuum to the solution.
  • the casting solution is prepared, it is cast into a sheet on a flat and level surface.
  • Casting is a well-known process that, briefly, involves pouring a solution on to a flat surface and using a casting bar having a set gap between the bar and the flat surface to pull the solution over the surface. The solution flows along the flat surface and is deposited into the form of a flat sheet having a thickness commensurate with the gap between the casting bar and the flat surface.
  • phase inversion is a known process resulting in a controlled transformation of a polymer from a liquid solution to a solid in a quenching environment.
  • quenching environment means any environment that causes a polymer to precipitate from a dissolved state into a solidified state.
  • the quenching of the cast sheet can occur in a single procedure or in more than one procedure.
  • the phase inversion process includes, for example, non-solvent induced phase inversion, temperature-induced phase inversion, vapor phase precipitation, evaporation and immersion precipitation processes, in which the polymer of the film precipitates from a solvent solution in some manner.
  • the specifics of each process are subject to, for example, the types and amounts of solvents employed, and the temperatures used.
  • the cast sheet can be immersed, either immediately or after some delay, such as 1 minute to 4 hours, in a quenching environment for a sufficient period to allow phase inversion.
  • the quenching of a cast sheet can involve simply moving the sheet into a coagulation bath of the quenching liquid.
  • the quenching of a cast sheet can involve exposing the sheet to an atmosphere saturated with the quench liquid, followed by moving the substrate and sheet into a coagulation bath of the quenching liquid. Exposing the shaped film precursor to a saturated atmosphere can be accomplished, for example, via a vapor diffusion chamber containing a vapor of the quench liquid, which may be, for example, water or an organic solvent.
  • the method of phase inversion can contribute to the pore size created in the film. Often, a vapor diffusion chamber may be needed to prepare ultrafiltration and nanofiltration films. In general, the cast flat sheet can be subjected to a vapor diffusion chamber quenching environment for anywhere between 30 seconds to 30 minutes, such as, 45seconds to 20 minutes, or 1 minute to 10 minutes, or 2 minutes to 8 minutes, again, depending on the solvents employed.
  • the quenching environment contains a liquid that is a non-solvent for the polymer or polymers in the sheet.
  • non-solvent when used in reference to a polymer, means a liquid that, when added to a solution of the polymer in a solvent, will cause phase separation of the solution at some concentration.
  • the quench liquid can include, for example, water as the non-solvent, typically at between about 30 to about 90 wt% of the quench liquid.
  • the quench liquid can also include a solvent selected from any of the same solvents discussed with respect to the casting solution, including, for example, one or more of N,N- dimethyl formamide, cyclohexanone, tetrahydrofuran, methanol, acetone, isopropyl alcohol, N,N-dimethylacetamide, and dimethyl sulfoxide.
  • a solvent selected from any of the same solvents discussed with respect to the casting solution, including, for example, one or more of N,N- dimethyl formamide, cyclohexanone, tetrahydrofuran, methanol, acetone, isopropyl alcohol, N,N-dimethylacetamide, and dimethyl sulfoxide.
  • the prepared porous polymer film can be washed and/or dried to remove excess solvent.
  • the film may also be subject to further processing.
  • the film may be subjected to deposition processes to deposit a thin layer of a coating on the top of the film.
  • deposition processes are known in the art, and include, for example, chemical vapor deposition and thin film deposition.
  • the porous polymer film can be employed in methods of treating effluent streams by filtering the effluent through the film.
  • the effluent stream can be a gas in gas stream, a gas in liquid stream, a liquid in liquid stream, or a suspended solid in liquid stream.
  • effluent treating methods require the film to withstand pressures of from 0 to 1000 psi, or 0 to 500 psi.
  • the effluent can be municipal wastewater. In some embodiments, the effluent can be industrial wastewater.
  • the films may also be employed to purify drinking water and in food and alcohol purification. The films may also be employed to separate oil and water or a gas from a mixture of gases.
  • the effluent can also be a biological stream, such as blood, protein, fermentation by-products, and the like.
  • the technology includes, for example, a method of filtering or separating organic or biologic matter carried in an aqueous effluent. The process can encompass flowing a filterable fluid containing organic or biologic material under pressure through the porous polymer film. As the fluid flows through the porous polymer film, an unfiltered part of the fluid can be discharged from an outlet.
  • each chemical component described is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, that is, on an active chemical basis, unless otherwise indicated.
  • each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade.
  • each chemical component described is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, that is, on an active chemical basis, unless otherwise indicated.
  • each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade.
  • hydrocarbyl substituent or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character.
  • hydrocarbyl groups include:
  • hydrocarbon substituents that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicy-nch-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form a ring);
  • aliphatic e.g., alkyl or alkenyl
  • alicyclic e.g., cycloalkyl, cycloalkenyl
  • substituted hydrocarbon substituents that is, substituents containing nonhydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);
  • hetero substituents that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms and encompass substituents as pyridyl, furyl, thienyl and imidazolyl.
  • Heteroatoms include sulfur, oxygen, and nitrogen.
  • no more than two, or no more than one, nonhydrocarbon substituent will be present for every ten carbon atoms in the hydro- carbyl group; alternatively, there may be no non-hydrocarb on substituents in the hydrocarbyl group.
  • a series of polyurethanes were prepared according to the following examples and evaluated for the ability to form stable and functional separation membranes.
  • Polymers were prepared from a combination of diisocyanate monomers, including dicyclohexylmethane-4,4'-diisocyanate (HMDI); isophorone diisocyanate (IPDI); and 4,4'-methylene bis(phenyl isocyanate) (MDI).
  • HMDI dicyclohexylmethane-4,4'-diisocyanate
  • IPDI isophorone diisocyanate
  • MDI 4,4'-methylene bis(phenyl isocyanate)
  • diisocyanate monomers were reacted with various diol (or polyol) chain extenders, selected from 1,4-phenylenediboronic acid (PDBA); hydrogenated bisphenol (HBPA); and 1,4-cyclohexanedimethanol (CHDM); and/or diamine chain extenders, including 4, 4'-methylenebis(2 -methylcyclohexylamine) (MHMDA); and isophorone diamine (IPDA); and 4,4'-methylenebis[N-(l-methylpropyl)-cyclohexanamine
  • PDBA 1,4-phenylenediboronic acid
  • HBPA hydrogenated bisphenol
  • CHDM 1,4-cyclohexanedimethanol
  • diamine chain extenders including 4, 4'-methylenebis(2 -methylcyclohexylamine) (MHMDA); and isophorone diamine (IPDA); and 4,4'-methylenebis[N-(l-methylpropyl)-cyclohexanamine
  • the viscosity was continuously monitored and adjusted with additional N- methylpyrrolidone charges to maintain good stirring.
  • the batch was cooled to room temperature and the viscosity was adjusted to 20 000 - 40 000 cPs with additional N-methylpyrrolidone charges.
  • the final product is a clear viscous liquid with no or slight yellow color.
  • Polymer example 1 (PEX1) was prepared in the following manner: hydrogenated bisphenol (HBPA, 32,4 g) and catalyst were charged to the reaction vessel with N-methylpyrrolidinone (NMP) (50 m ). The mixture was heated to 110 °C; at which time the diisocyanate (HDMI, 70.7 g) was added in one batch. The reaction mixture was allowed to exotherm naturally and was them cooled to 110 °C, where the reaction mixture was held for 30 minutes. The reaction mixture was cooled to 50 °C, after which the reaction mixture was diluted with additional NMP. The diamine (MHDMA, 32.1g) was then added in one portion. The resulting material was 16 wt % solids in a solution of NMP, and had a number average molecular weight (Mn) of 38,900 Daltons via GPC with polystyrene standards.
  • NMP N-methylpyrrolidinone
  • Polymer examples 2 through 4 (PEX2 - PEX4) were prepared in a similar manner as PEX1 according to the compositions in Table 1.
  • Polymeric products were characterized by Brookfield viscosity at ambient temperature (typically 21 to 24 C), and glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC).
  • Tg glass transition temperature
  • DSC differential scanning calorimetry
  • the turbidity of the polymer compositions were measured using a model Ml 00+ infrared Turbidity meter from HF Scientific. Turbidity measurements are reported in nephelometric turbidity units (NTU). Turbidity measurements above about 50 NTU indicate a significant amount of undissolved polymer.
  • NTU nephelometric turbidity units
  • thermoplastic polyurethane TPU
  • NMP thermoplastic polyurethane
  • COMP2 polycarbonate- based aliphatic Thermoplastic Polyurethane
  • Turbidity reading 85.5 NTU indicating poor dissolution of the polyurethane in NMP solvent.
  • Compositions, literature value glass transition temperatures and turbidity measurements of the comparative thermoplastic polyurethanes are shown in Table 2. Table 2. Comparative Thermoplastic Polyurethanes
  • Membrane Casting - Inventive and Comparative polyurethane casting compositions were casted onto a polyester non-woven substrate having an air permeability of 0.7 cc/cm2/s, a basis weight of 83 g/m2, and a thickness of 0.095 millimeters.
  • a 6 mil thick casting solution was applied using a stainless steel casting blade.
  • the resulting wet coating was quenched into deionized water at 25 ⁇ C and rinsed at 40 °C.
  • the resulting membranes were stored in deionized water until water permeability was measured.
  • Table 3 Membrane Performance [0095] Table 3 demonstrates that the Thermoplastic Polyurethanes did not provide high performance porous membranes. Adhesion of the membrane face of COMP1 TPU to the backside of the nonwoven during storage resulted in a membrane which was unacceptable to test the water flux. Incomplete dissolution of Casting Composition COMP2 TPU gave an unacceptable Turbidity measurement. Comparative Casting Solution COMP3 TPU resulted in a membrane with low water permeability. Each of the Inventive Casting Compositions, PEX1, PEX2, PEX3, PEX4 gave low Turbidity readings which indicated good dissolution of the resin in NMP solvent.
  • a series of functionalized polyurethanes were prepared according to the following examples and evaluated for the ability to form stable and functional separation membranes.
  • Polymer example 5 Sulfonic acid modified PU (acid number 18) - 2,2'-bis-(4-hydroxycyclohexyl)propane was dissolved in 80g NMP and heated uptol00°C. Desmodur W (H12MDI) and K-Kat348 [Bi(Oct)3] catalyst was added. Strong exotherm was observed that increased the reactor temperature of the reactor to 127°C with cooling. The reactor was held at 110°C-115°C for 2 hours. A 10% solution of 3,5-Diaminotrimethylbenzenesulfonic acid with triethylamine was prepared in NMP, which then was added to the reactor at 60°C.
  • the reactor was then heated to 85°C and held at that temperature for 3 hours. Then 400 g NMP added and the reactor was cooled to 45°C . Methylenebis(2-methyl- cyclohexylamine) was added slowly to the reactor until the isocyanate concentration reached zero. Then the solution was cooled to RT and more NMP was added to adjust the viscosity of the reactor to 20000-30000 cps.
  • Polymer example 6 (PEX6): Zwitterion modified PU - 2,2'-bis-(4-hy- droxycyclohexyl)propane was dissolved in 80g NMP at 100°C. Then Desmodur W (H12MDI) and K-Kat348 [Bi(Oct)3] catalyst was added. Strong exotherm was observed that increased the reactor temperature to 127°C with cooling. The reactor was held for 2 hours at 110°C-115°C. A 5% solution of 3, 5 -Diaminotrimethylbenzenesulfonic acid DABS and methyldiethanolamine was prepared separately at 70°C with triethylamine, which was then added to the reactor at 80°C.
  • PEX6 Zwitterion modified PU - 2,2'-bis-(4-hy- droxycyclohexyl)propane was dissolved in 80g NMP at 100°C. Then Desmodur W (H12MDI) and K-Kat
  • the reactor temperature was increased to 85°C and reacted for 2 hours.
  • the reactor was then cooled to 45°C and the Methyl enebis(2 -methylcyclohexylamine diamine was added slowly until the isocyanate concentration reached zero.
  • NMP was added during the extension to control the viscosity.
  • AT the end of the reaction the solution was cooled to RT and more NMP was added to reduce viscosity to 20000- 30000 cps.
  • Polymer example 7 (PEX7): 2K MPEG modified PU - The 2,2'-bis-(4-hy- droxycyclohexyl)propane diol was dissolved in 100g NMP and then Desmodur W (H12MDI) was added together with the K-Kat348 [Bi(Oct)3] catalyst. Strong exotherm was observed that increased the temperature of the reactor to 127°C with cooling. The reactor was held for 2 hours at 110°C-115°C. Monomethyl-polyeth- yleneglycol (MPEG) and trimethyololpropane was melted and dissolved in 50g NMP, which was then charged to the reactor at 95°C.
  • MPEG Monomethyl-polyeth- yleneglycol
  • trimethyololpropane was melted and dissolved in 50g NMP, which was then charged to the reactor at 95°C.
  • Table 6 (a and b), Table 7 (a and b), and Table 8 (a and b) provide the elemental analysis at various depths for PEG modified, sulfonic acid modified, and zwitterionic PU membranes.
  • sulfonic acid and zwitterion modified membrane the presence of sulfur is an indication of sulfonic acid groups.
  • PEG modified membranes showed the presence of carbon, nitrogen, and oxygen which are constituent elements in both PEG and polyurethanes.
  • Table 6 Elemental analysis of sulfonic acid modified membrane after chemi- cal treatment.
  • Table 7 Elemental analysis of zwitterion modified membrane before chemical treatment.
  • Table 7 Elemental analysis of zwitterion acid modified membrane after chemical treatment.
  • Polymer example 8 (PEX8): 55.5g 2,2'-bis-(4-hydroxycyclohexyl)propane was mixed with 100g NMP and heated up tolOO°C, then 92.5g Desmodur W and 0.06g K-Kat348 catalyst was added. Strong exotherm was observed that increased the temperature to 127°C. The reactor was held for 2 hours at 110°C-l 15°C. Then 250 g NMP was added, and the reactor was cooled to 60°C. Then 6g meth- ylenebis(2-methylcyclohexylamine was added as 20% solution in NMP, then further 150 g NMP was added as the reactor was cooled to 45°C.
  • Polymeric products were characterized by Brookfield viscosity at ambient temperature (typically 21 °C to 24°C), and glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC).
  • Tg glass transition temperature
  • DSC differential scanning calorimetry
  • the turbidity of the polymer compositions was measured using a model M100+ infrared Turbidity meter from HF Scientific. Turbidity measurements are reported in nephelometric turbidity units (NTU). Turbidity measurements above about 50 NTU indicate a significant amount of undissolved polymer. Polymer composition and analysis is summarized below (Table 9).
  • PEX8 was cast into a membrane and tested for water permeability according to the steps above for PEX1 to PEX4.
  • the average water permeability for the triplicate sample is shown in Table 10.
  • Table 10 demonstrates that the Inventive Casting Compositions, PEX8 gave low Turbidity readings which indicated good dissolution of the resin in NMP solvent.
  • Solvent resistance The crosslinked polyurethane membrane was tested for solvent resistance. To measure the solvent resistance, several standalone (without nonwoven support) membrane films were prepared from crosslinked and non- crosslinked polyurethanes. The corresponding weights of each film were measured. Both the crosslinked and non-crosslinked membrane films were then immersed in various organic solvents including NMP, Hexane, Toluene, IPA, Ethanol, DMF, DMAc, DPGME, and Sulfolane. The non-crosslinked membrane films spontaneously dissolved or degraded in all of the organic solvents whereas the crosslinked films maintained their structure. After 1 hour of immersion, crosslinked membrane films were taken out of the solvent, dried, and weighed. Table 11 shows the weight of the films before and after immersion in organic solvents. All crosslinked films showed minimal or no loss in weight after subjecting them to organic solvents.
  • Table 12 demonstrates the percent change in flux of both crosslinked and non-crosslinked polyurethane membranes after soaking in concentrated cleaning chemistries at elevated temperatures. As compared to non-crosslinked membrane films, the crosslinked membranes films showed minimal or significantly lower change in water flux indicating a stronger resistance against the chemistries.

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Abstract

La technologie divulguée concerne des films polymères poreux fabriqués à partir de compositions polymères de polyuréthane ou de polyurée.
PCT/US2025/030759 2024-05-30 2025-05-23 Films polymères poreux de polyuréthane et de polyurée Pending WO2025250460A1 (fr)

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