Precision filter membrane

Abstract

The present application relates to a multi-zone, unsupported, microporous high-throughput membrane. The membrane comprises a first microporous zone, a second microporous zone, and a third microporous zone, wherein the first, second, and third microporous zones are integral with one another and the third microporous zone is disposed between the first and second microporous zones. Further aspects of the present application include methods for manufacturing the membrane and a filtration cartridge having the membrane.

Description

[Technical Field]

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 938,412, filed November 21, 2019, which is incorporated herein by reference in its entirety.

[0002] Field This application relates to microfiltration membranes that achieve superior throughput performance. [Background technology]

[0003] background Throughput performance is becoming increasingly important for filtration applications. One way to improve filter throughput is to use multiple layers of membrane in the filtration device. For example, Millipore Express® SHC manufactured by MilliporeSigma contains two layers of membrane. Sartoguard NF manufactured by Sartorius contains three layers of separation media. However, this approach results in increased manufacturing costs due to the multiple membrane layers required to achieve the desired throughput.

[0004] Another way to improve filter throughput is to optimize the membrane structure. U.S. Patent No. 7,942,274 to Kools et al. discloses a method for producing high-throughput membranes using an additional step to modify the dense membrane surface by ablation or solvation. Because the modification is a separate process step, it adds extra cost to the resulting membrane.

[0005] U.S. Patent Application Publication No. 2014 / 0339166A to Wixwat et al. discloses a method for fabricating high-throughput membranes having channels in a porous membrane portion created by removing introduced fibers. U.S. Patent Application Publication No. 2014 / 0339164A to Liang et al. and U.S. Patent Application Publication No. 2014 / 0339165A to Han et al. disclose methods for fabricating high-throughput membranes by removing introduced particles from a first porous portion of the membrane. Both of these processes require extra labor to mix the particles or fibers into the membrane formulation and require additional process steps to remove the particles or fibers.

[0006] Asymmetric membranes have been developed to achieve high flux rates, which also result in improved throughput compared to symmetric membranes. See U.S. Patent No. 4,261,834 to deWinter. The most common asymmetric membranes have a gradient structure in which the pore size gradually and continuously increases from one side to the other. See U.S. Patent No. 4,629,563 to Wrasidlo. Another type of asymmetric membrane structure has a retention zone within the asymmetric membrane, where the pore size decreases and then increases again. See U.S. Patent No. 4,933,081 to Sasaki et al. Advantages of "hourglass"-type asymmetric membranes include high flux rates and reduced risk of retention loss due to surface scratches. However, because they are formed by a single zone casting process, the membrane structure is highly dependent on the membrane formation process, particularly the air exposure process step. This reduces process robustness and can therefore produce non-uniform membranes.

[0007] Membranes with multi-zone structures are scientifically more attractive because each zone can be fine-tuned to achieve overall improved performance. Multi-zone microfiltration membranes containing at least one symmetrical retention zone and at least one pre-filtration zone were first patented using sequential casting. See U.S. Patent No. 5,620,790 to Holzki et al. As described in U.S. Patent No. 7,208,200 to Kools, sequential casting likely creates a distinct boundary or region with a dense, thin-film-like structure between the symmetrical retention zone and the pre-filtration zone. This likely leads to a dramatic decrease in membrane throughput due to particle accumulation at the interface. Furthermore, a symmetrical retention zone morphology leads to low throughput. U.S. Patent No. 7,208,200 to Kools discloses a co-casting process that smooths the transition between zones, thus improving performance. However, there is no mention of how to achieve high throughput performance.

[0008] U.S. Patent No. 8,840,791 to Wang et al. discloses a multi-zone microfiltration membrane with a three-zone structure including an asymmetric zone, a symmetric and / or asymmetric zone, and an interface zone between these two zones. The disclosed membrane was fabricated via a two-stage sequential casting process, as described in U.S. Patent No. 5,620,790 to Holzki et al. The membrane fabrication process indicates that the interface zone was not intentionally created as a result of casting an additional lacquer. Instead, as described in U.S. Patent No. 8,840,791 to Wang et al., it is formed by a mixture of a first and a second polymer lacquer. As described in U.S. Patent No. 5,620,790 to Holzki et al., no mixing of the individual zones occurs. Furthermore, this patent makes no mention of casting additional filtration zones to enable significant improvements in membrane throughput.

[0009] The present application is directed to overcoming these and other deficiencies in the art. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] U.S. Patent No. 7,942,274 [Patent Document 2] U.S. Patent Application Publication No. 2014 / 0339166A [Patent Document 3] U.S. Patent Application Publication No. 2014 / 0339164A [Patent Document 4] U.S. Patent Application Publication No. 2014 / 0339165A [Patent Document 5] U.S. Patent No. 4,261,834 [Patent Document 6] U.S. Patent No. 4,629,563 [Patent Document 7] U.S. Patent No. 4,933,081 [Patent Document 8] U.S. Patent No. 5,620,790 [Patent Document 9] U.S. Patent No. 7,208,200 [Patent Document 10] U.S. Patent No. 8,840,791 Summary of the Invention

[0011] overview This application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric. The first, second, and third microporous zones are integral with one another, with the third microporous zone being positioned between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0012] A second aspect of the present application relates to a filtration cartridge that includes a housing and a membrane of the present application disposed within the housing.

[0013] A further aspect of the present application relates to a process for forming a multi-zone, microporous, high-throughput filtration membrane having a strain at break of at least 20%. The process includes providing a solution of a polymer and a solvent for the polymer, simultaneously or sequentially casting the solution onto a support as three separate zones to form a multi-zone liquid sheet, allowing phase separation of the solution of the three separate zones, and separating the multi-zone, microporous, high-throughput filtration membrane from the support. The membrane includes a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric, wherein the third microporous zone is disposed between the first and second microporous zones. The first, second, and third microporous zones are integral with one another, and the membrane has a throughput (L / m2) greater than -11.65x + 1088.5 as measured using whey broth. 2), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0014] Another aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane, wherein the membrane has a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric, and the third microporous zone is disposed between the first and second microporous zones, and the first, second, and third microporous zones are integral with one another. Further, the first, second, and / or third microporous zones comprise a blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and copolymer of acrylic or methacrylic polymer, and a second polymer, wherein the second polymer is selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. The membrane has a breaking strain of at least 20% and a throughput (L / m) of greater than -11.65x + 1088.5 as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0015] A further aspect of the present application relates to a filtration cartridge including a housing and a pleated membrane disposed within the housing, wherein the membrane has a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric, and the third microporous zone is disposed between the first and second microporous zones, with the first, second, and third microporous zones integral with one another. The first, second, and / or third microporous zones comprise a blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and copolymer of acrylic or methacrylic polymer, and a second polymer, wherein the second polymer is selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. The membrane has a breaking strain of at least 20% and a throughput (L / m) of greater than -11.65x + 1088.5 as measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi); and wherein the housing has a flow rate of 0.11 m per inch of housing height. 2 It includes an effective membrane area of ​​over 1000m.

[0016] A further aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a symmetric first microporous zone, an asymmetric second microporous zone, and an asymmetric third microporous zone. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0017] An additional aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a symmetric first microporous zone, a symmetric second microporous zone, and an asymmetric third microporous zone. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0018] Another aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a first microporous zone that is asymmetric, a second microporous zone that is symmetric, and a third microporous zone that is asymmetric. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0019] A further aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes an asymmetric first microporous zone, an asymmetric second microporous zone, and an asymmetric third microporous zone. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0020] Another aspect of the present application relates to an unsupported, microporous, high-throughput filtration membrane having a breaking strain of at least 20% and a bubble point (psi) of about 15 to 50. The membrane has a throughput (L / m2) greater than -11.65x + 1088.5, as measured using whey broth.2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0021] A further aspect of the present application relates to an unsupported, microporous, high-throughput filtration membrane having a breaking strain of at least 20% and a bubble point (psi) of about 15 to 50. The membrane has a throughput (L / m2) greater than -11.65x + 1188.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1469.4, where x is the bubble point (psi).

[0022] A final aspect of the present application relates to an unsupported, microporous, high-throughput filtration membrane having a breaking strain of at least 20% and a bubble point (psi) of about 15 to 50. The membrane has a throughput (L / m) greater than -11.65x + 1288.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1569.4, where x is the bubble point (psi).

[0023] In life science and pharmaceutical filtration applications, many devices are constructed with two or more layers of microfiltration membranes and / or other separation media to achieve high-throughput performance. This application relates to a high-throughput microfiltration membrane and its manufacturing process. The membrane contains three casting zones, including (a) a symmetric or asymmetric first zone, (b) a symmetric or asymmetric second zone, and (c) an asymmetric third zone, where the third zone is positioned between the first two zones. The casting process can be triple-slot co-cast or triple-slot sequential cast. The membranes of this application achieve improved throughput compared to Millipore Express® products of the same pore size.

[0024] The resulting membranes of this application, having a new morphology and made with this new process, provide significant improvements to membrane throughput. Furthermore, the new morphology of the membrane allows it to be pleated without compromising its filtration properties, such as bacterial retention. [The present invention 1001] 1. A multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain to break of at least 20%, The membrane is a first microporous zone, which may be symmetric or asymmetric; a second microporous zone, which may be symmetric or asymmetric; a third microporous zone that is asymmetric; Including, the first, second, and third microporous zones are integral with one another, the third microporous zone being disposed between the first and second microporous zones; and The membrane has a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi); Multi-zone, unsupported microporous high-throughput filtration membrane. [The present invention 1002] 1001. A membrane according to the present invention, wherein the first microporous zone is 5-140 μm thick, the second microporous zone is 10-140 μm thick, and the third microporous zone is 50-140 μm thick. [The present invention 1003] 1001. The membrane of the present invention having a total thickness of 65 to 300 μm. [The present invention 1004] The membrane has a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ) wherein x is the bubble point (psi). [The present invention 1005] The membrane has a throughput (L / m) greater than -11.65x + 1188.5 when measured using whey broth.2 ) where x is the bubble point (psi). [The present invention 1006] The membrane has a throughput (L / m) greater than -11.65x + 1288.5 when measured using whey broth. 2 ) wherein x is the bubble point (psi). [The present invention 1007] The membrane had a throughput (L / m) greater than -20.23x + 1369.4 when measured using EMD soy broth. 2 ) wherein x is the bubble point (psi). [The present invention 1008] The membrane had a throughput (L / m) greater than -20.23x + 1469.4 when measured using EMD soy broth. 2 ) wherein x is the bubble point (psi). [The present invention 1009] The membrane had a throughput (L / m) greater than -20.23x + 1569.4 when measured using EMD soy broth. 2 ) wherein x is the bubble point (psi). [The present invention 1010] 1001. A film of the present invention having a breaking strain of at least 25%. [The present invention 1011] A film of the present invention 1010 having a breaking strain of at least 30%. [The present invention 1012] 1001. The membrane of the present invention, wherein the first, second, and third microporous zones comprise one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymers, methacrylic polymers, and copolymers of acrylic or methacrylic polymers. [The present invention 1013] The membrane of the present invention 1001, wherein the first, second, and / or third microporous zones are hydrophilic. [The present invention 1014] 1013. The membrane of the present invention, wherein the first, second, and / or third microporous zones comprise a hydrophilic polymer independently selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl pyridine, polyethylene imine, and polyoxazoline. [The present invention 1015] 1014. The membrane of claim 10, wherein the hydrophilic polymer comprises poly(2-ethyl-2-oxazoline). [The present invention 1016] The membrane of the present invention 1014, wherein the hydrophilic polymer is crosslinked. [The present invention 1017] 1016. The membrane of the present invention, wherein the hydrophilic polymer is crosslinked by an electron beam. [The present invention 1018] 1017. The membrane of claim 1017, wherein the hydrophilic polymer is crosslinked by an electron beam having a dose of about 20 to 150 kGy. [The present invention 1019] 1014. The membrane of claim 10, wherein the first, second, and / or third microporous zones independently comprise polyethersulfone and poly(2-ethyl-2-oxazoline). [The present invention 1020] 1001. A membrane of the present invention that can be pleated without loss of membrane retention. [The present invention 1021] The membrane of the present invention 1001, which is pleated. [The present invention 1022] a hydrophilic coating on the membrane The membrane of the present invention 1001 further comprises: [The present invention 1023] Housing and a membrane of the present invention 1001 disposed within the housing; a filtration cartridge comprising: [The present invention 1024] 1023. A cartridge according to claim 1023, wherein the first microporous zone is 5 to 140 μm thick, the second microporous zone is 10 to 140 μm thick, and the third microporous zone is 50 to 140 μm thick. [The present invention 1025] The membrane has a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ) wherein x is the bubble point (psi). [The present invention 1026] The membrane has a throughput (L / m) greater than -11.65x + 1188.5 when measured using whey broth. 2 1025. The cartridge of claim 10, wherein x is the bubble point (psi). [The present invention 1027] The membrane has a throughput (L / m) greater than -11.65x + 1288.5 when measured using whey broth. 2 1026. The cartridge of claim 1026, wherein x is the bubble point (psi). [The present invention 1028] The membrane had a throughput (L / m) greater than -20.23x + 1369.4 when measured using EMD soy broth. 2 ) wherein x is the bubble point (psi). [The present invention 1029] The membrane had a throughput (L / m) greater than -20.23x + 1469.4 when measured using EMD soy broth. 2 1028. The cartridge of claim 1028, wherein x is the bubble point (psi). [The present invention 1030] The membrane had a throughput (L / m) greater than -20.23x + 1569.4 when measured using EMD soy broth. 2 1029. The cartridge of claim 1029, wherein x is the bubble point (psi). [The present invention 1031] 1023. The cartridge of claim 1023, wherein the membrane has a breaking strain of greater than 25%. [The present invention 1032] 1031. The cartridge of claim 10, wherein the membrane has a breaking strain of greater than 30%. [The present invention 1033] The cartridge of the present invention 1023, wherein the first, second, and third microporous zones comprise one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymers, methacrylic polymers, and copolymers of acrylic or methacrylic polymers. [The present invention 1034] The cartridge of the present invention 1023, wherein the first, second, and / or third microporous zones are hydrophilic. [This invention 1035] The first, second, and / or third microporous zones may comprise: A blend of one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and copolymer of acrylic or methacrylic polymer with one or more hydrophilic polymers selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. The cartridge of the present invention 1034, comprising: [The present invention 1036] 1035. The cartridge of claim 10, wherein the hydrophilic polymer comprises poly(2-ethyl-2-oxazoline). [This invention 1037] The cartridge of the present invention 1035, wherein the hydrophilic polymer is crosslinked. [The present invention 1038] 1037. The cartridge of claim 1037, wherein the hydrophilic polymer is crosslinked by an electron beam. [This invention 1039] The cartridge of the present invention 1038, wherein the hydrophilic polymer is crosslinked by an electron beam at a dose of about 20 to 150 kGy. [The present invention 1040] 1023. The cartridge of claim 1023, wherein the membrane is pleated. [The present invention 1041] 1. A method for forming a multi-zone, microporous, high-throughput filtration membrane having a breaking strain of at least 20%, comprising: The method comprises: providing a solution of a polymer and a solvent for the polymer; casting the solution onto a substrate as three separate zones simultaneously or sequentially to form a multi-zone liquid sheet; causing a phase separation of the solution into three separate zones; and Separating the multi-zone, microporous high-throughput filtration membrane from the support Including, The membrane is a first microporous zone, which may be symmetric or asymmetric; a second microporous zone, which may be symmetric or asymmetric; a third microporous zone that is asymmetric; Including, the first, second, and third microporous zones are integral with one another, the third microporous zone being disposed between the first and second microporous zones; and The membrane has a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi); method. [The present invention 1042] 1042. The method of claim 1041, wherein the first microporous zone is 5 to 140 μm thick, the second microporous zone is 10 to 140 μm thick, and the third microporous zone is 50 to 140 μm thick. [This invention 1043] The membrane has a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ) wherein x is the bubble point (psi). [This invention 1044] The membrane has a throughput (L / m) greater than -11.65x + 1188.5 when measured using whey broth. 2 ) wherein x is the bubble point (psi). [This invention 1045] The membrane has a throughput (L / m) greater than -11.65x + 1288.5 when measured using whey broth. 2 ) wherein x is the bubble point (psi). [The present invention 1046] The membrane had a throughput (L / m) greater than -20.23x + 1369.4 when measured using EMD soy broth. 2 ) wherein x is the bubble point (psi). [This invention 1047] The membrane had a throughput (L / m) greater than -20.23x + 1469.4 when measured using EMD soy broth. 2 ) wherein x is the bubble point (psi). [This invention 1048] The membrane had a throughput (L / m) greater than -20.23x + 1569.4 when measured using EMD soy broth. 2 ) wherein x is the bubble point (psi). [This invention 1049] 1041. The method of claim 1041, wherein the membrane has a breaking strain of greater than 25%. [The present invention 1050] 1049. The method of claim 1049, wherein the membrane has a breaking strain of greater than 30%. [This invention 1051] 1041. The method of claim 1041, wherein the first, second, and third microporous zones comprise one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymers, methacrylic polymers, and copolymers of acrylic or methacrylic polymers. [This invention 1052] The method of claim 1041, wherein the first, second, and / or third microporous zones are hydrophilic. [This invention 1053] 1041. The method of claim 1041, wherein the first, second, and / or third microporous zones further comprise one or more hydrophilic polymers independently selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl pyridine, polyethylene imine, and polyoxazoline. [This invention 1054] 1053. The method of claim 1053, wherein the hydrophilic polymer comprises poly(2-ethyl-2-oxazoline). [This invention 1055] The method of claim 1053, wherein the hydrophilic polymer is crosslinked. [This invention 1056] The method of claim 1055, wherein the hydrophilic polymer is crosslinked by an electron beam. [This invention 1057] The method of claim 1056, wherein the hydrophilic polymer is crosslinked by electron beam at a dose of about 20 to 150 kGy. [This invention 1058] 1041. The method of claim 1041, wherein the membrane is pleated. [This invention 1059] 1041. The method of claim 1041, wherein said solution comprises at least one polymer and at least one solvent for said polymer. [The present invention 1060] 1041. The method of claim 10, wherein said solution has an upper critical solution temperature. [This invention 1061] 1041. The method of claim 10, wherein said solution has a lower critical solution temperature. [This invention 1062] 1061. The process of claim 1061, wherein said step of causing phase separation is carried out by heating said solution above a lower critical solution temperature of said solution to cause phase separation. [This invention 1063] 1041. The method of claim 1041, wherein the step of causing phase separation is carried out by vapor-induced phase separation. [This invention 1064] 1041. The process of claim 1041, wherein said solution further comprises one or more porogens independently selected from the group consisting of formamide, alcohol, polyhydric compounds, water, polyethylene glycol, calcium chloride, and lithium chloride. [This invention 1065] coating a hydrophilic substrate onto the membrane The method of the present invention 1041 further comprising: [The present invention 1066] 1041. The method of claim 1041, wherein said casting steps are performed sequentially. [This invention 1067] 1041. The method of claim 1041, wherein said casting steps are performed simultaneously. [The present invention 1068] The method of claim 1067, wherein said casting step is performed by co-casting. [This invention 1069] a first microporous zone, which may be symmetric or asymmetric; a second microporous zone, which may be symmetric or asymmetric; a third microporous zone that is asymmetric; 1. A multi-zone, unsupported, microporous high-throughput filtration membrane comprising a membrane having: the first, second, and third microporous zones are integral with one another, the third microporous zone being disposed between the first and second microporous zones; and The first, second, and / or third microporous zones may comprise: A blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and copolymer of acrylic or methacrylic polymer, and a second polymer selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. and The membrane has a breaking strain of at least 20% and a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi); Multi-zone, unsupported microporous high-throughput filtration membrane. [The present invention 1070] 1069. The membrane of claim 1069, wherein the first polymer is PES and the second polymer is poly(2-ethyl-2-oxazoline). [This invention 1071] 1069. The membrane of the present invention, which is crosslinked. [This invention 1072] 1071. The membrane of claim 1071, wherein the first polymer is PES and the second polymer is polyoxazoline, and the membrane is crosslinked by electron beam. [This invention 1073] 1072. The membrane of claim 1072, which is crosslinked by an electron beam having a dose of about 20 to 150 kGy. [This invention 1074] Housing and a pleated membrane disposed within the housing; and A filtration cartridge comprising: The membrane is a first microporous zone, which may be symmetric or asymmetric; a second microporous zone, which may be symmetric or asymmetric; a third microporous zone that is asymmetric; Including, the first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones; The first, second, and / or third microporous zones may comprise: A blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and copolymer of acrylic or methacrylic polymer, and a second polymer selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. Including, The membrane has a breaking strain of at least 20% and a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi), and The housing has a thermal conductivity of 0.11 m per inch of housing height 2 Including an effective membrane area of ​​over Filtration cartridge. [This invention 1075] The housing has a thickness of 0.11 m per inch of housing height 2 The filtration cartridge of the present invention includes an effective membrane area of ​​more than 1023. [This invention 1076] 1. An unsupported, microporous, high-throughput filtration membrane having a breaking strain of at least 20% and a bubble point (psi) of about 15 to 50; The membrane has a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi); Unsupported microporous high-throughput filtration membrane. [This invention 1077] The membrane of the present invention 1076, which is a multi-zone membrane. [This invention 1078] The membrane of the present invention 1077 comprises three zones. [This invention 1079] The zone is a first microporous zone; a second microporous zone; a third microporous zone; Including, the first, second, and third microporous zones being integral with one another, with the third microporous zone being disposed between the first and second microporous zones; The membrane of the present invention 1078. [The present invention 1080] 1079. The membrane of claim 1079, wherein the first microporous zone is 5 to 140 μm thick, the second microporous zone is 10 to 140 μm thick, and the third microporous zone is 50 to 140 μm thick. [This invention 1081] 1076. The membrane of claim 1076 having a total thickness of 65 to 300 μm. [This invention 1082] The membrane has a throughput (L / m) greater than -11.65x + 1088.5 when measured using whey broth. 2 1076. The membrane of claim 10, wherein x is the bubble point (psi). [This invention 1083] The membrane has a throughput (L / m) greater than -11.65x + 1188.5 when measured using whey broth.2 ) wherein x is the bubble point (psi). [This invention 1084] The membrane has a throughput (L / m) greater than -11.65x + 1288.5 when measured using whey broth. 2 ) wherein x is the bubble point (psi). [This invention 1085] The membrane had a throughput (L / m) greater than -20.23x + 1369.4 when measured using EMD soy broth. 2 1076. The membrane of claim 10, wherein x is the bubble point (psi). [The present invention 1086] The membrane had a throughput (L / m) greater than -20.23x + 1469.4 when measured using EMD soy broth. 2 1085 membranes of the present invention having the formula: x = bubble point (psi). [This invention 1087] The membrane had a throughput (L / m) greater than -20.23x + 1569.4 when measured using EMD soy broth. 2 1086. The membrane of claim 1086, wherein x is the bubble point (psi). [This invention 1088] 1076. A membrane of the present invention having a breaking strain of at least 25%. [This invention 1089] 1088. A membrane of the present invention having a breaking strain of at least 30%. [The present invention 1090] 1079. The membrane of claim 1079, wherein the first, second, and third microporous zones comprise one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymers, methacrylic polymers, and copolymers of acrylic or methacrylic polymers. [This invention 1091] 1079. The membrane of claim 1079, wherein the first, second, and / or third microporous zones are hydrophilic. [This invention 1092] 1091. The membrane of claim 1091, wherein the first, second, and / or third microporous zones comprise a hydrophilic polymer independently selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl pyridine, polyethylene imine, and polyoxazoline. [This invention 1093] 1092. The membrane of claim 10, wherein the hydrophilic polymer comprises poly(2-ethyl-2-oxazoline). [This invention 1094] The membrane of the present invention 1092, wherein the hydrophilic polymer is crosslinked. [This invention 1095] 1094. The membrane of claim 10, wherein the hydrophilic polymer is crosslinked by an electron beam. [This invention 1096] 1095. The membrane of claim 10, wherein the hydrophilic polymer is crosslinked by an electron beam having a dose of about 20 to 150 kGy. [This invention 1097] 1079. The membrane of claim 1079, wherein the first, second, and / or third microporous zones independently comprise polyethersulfone and poly(2-ethyl-2-oxazoline). [This invention 1098] 1076. A membrane according to claim 1076, which can be pleated without loss of membrane retention. [This invention 1099] 1076. The membrane of the present invention, which is pleated. [The present invention 1100] a hydrophilic coating on the membrane The membrane of the present invention 1076 further comprising: [Brief explanation of the drawings]

[0025] [Figure 1] Figures 1A-1B are SEM micrographs of the cross-sections of high-throughput triple-zone membrane 2A and membrane 2B with hydrophilic coating; scale bar 100 µm. [Figure 2A] 2A-2C are SEM micrographs of cross sections of triple-zone high-throughput hydrophilic membranes 3A, 3C, and 3F, respectively, of the present application; scale bar 100 μm. [Figure 2B] See legend to Figure 2A. [Figure 2C] See legend to Figure 2A. [Figure 3] FIG. 1 is a perspective view, partially in section, of an exemplary filter cartridge of the present application. [Figure 4] FIG. 2 is a cross-sectional perspective view of an exemplary filter cartridge of the present application positioned within a housing in use. [Figure 5] FIG. 1 is a side view of an apparatus useful in carrying out the process for producing high-throughput multi-zone membranes of the present application. [Figure 6] 1 is a graphical depiction of particle size distributions of whey and EMD soy challenge streams. Particle size analysis data was collected using a Malvern MasterSizer® particle size analyzer. [Figure 7] 7A-7B are schematic illustrations of the throughput of EMD soy (FIG. 7A) and whey (FIG. 7B) through membranes of the present application. [Figure 8] 8A-8B are schematic illustrations of the throughput of EMD soy (FIG. 8A) and whey (FIG. 8B) through membranes from commercially available filters. [Figure 9] 9A-9B are SEM micrographs of pleated triple-zone hydrophilic membrane 3A and membrane 3C, respectively; scale bar 100 μm. [Figure 10]10A-10B are SEM micrographs of pleated commercially available membranes, Millipore Express® PLUS 0.2 μm (FIG. 10A) and Millipore Express® 0.5 μm (FIG. 10B); scale bar 100 μm. DETAILED DESCRIPTION OF THE INVENTION

[0026] Detailed Description A first aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0027] This application relates to an integrated triple-zone high-throughput porous membrane and its method of manufacture by triple slot casting three polymer mixes onto a support to form a triple-zone nascent membrane, and immersing the nascent membrane in a liquid coagulation bath to form a porous membrane. After formation, the porous membrane is extracted to remove all solvents and other unwanted chemicals, and then dried.

[0028] In one embodiment of the present application, the first microporous zone of the membrane is 5 to 140 μm thick, the second microporous zone is 10 to 140 μm thick, and the third microporous zone is 50 to 140 μm thick.

[0029] As used herein, "symmetric" refers to a membrane or zone having a nearly uniform pore size distribution throughout the membrane or zone.

[0030] As used herein, "asymmetric" refers to a membrane or zone whose pores have diameters that vary continuously or discontinuously across the thickness of the membrane or zone.

[0031] In this application, a "layer" of membrane is defined as an individual membrane sheet. One or more layers of membrane can be used in a filter to remove particles.

[0032] In this application, a "zone" is a region within a membrane layer that has different physical properties than surrounding or adjacent zones. A membrane layer can contain one, two, three, or even more zones. One or more membrane layers with multiple zones can be used in a filter to remove particles of different sizes.

[0033] Similarly, the term "integral" refers to a structure that is formed of multiple zones, and often different polymeric materials, but that is bonded together so as to behave as a single structure and not delaminate or separate in normal use.

[0034] The "throughput" of a filter is defined as the amount of fluid that can be processed by the filter until a filtration endpoint is reached. This endpoint can be based on the maximum processing time to filter a batch, or, in the case of constant pressure operation, the minimum filter flux compared to the initial clean water flux. In this application, filter throughput is defined as the maximum volume of fluid that can be filtered by the filter. Because filter throughput depends on the membrane used, membrane throughput is typically measured to predict filter throughput. In the case of constant pressure operation, the volume of fluid filtered per area of ​​the membrane is the membrane throughput. The maximum volume filtered at 90% of the membrane's initial flux is called V90 and is expressed in liters per square meter (L / m 2 ) Filter or membrane throughput is often interchangeable with filter or membrane capacity.

[0035] The first zone is a thin symmetric or asymmetric zone with pore sizes between 0.02 and 20 μm, with a preferred pore size of about 2 μm. For some life science applications requiring high retention performance, this first zone can be a high-density zone to provide greater assurance of retention. The first zone can be about 5 to 100 μm thick, with an exemplary preferred thickness of about 10 μm.

[0036] The second zone can be symmetric or asymmetric, with pore sizes ranging from 0.05 μm to 200 μm; the preferred pore size needs to be adjusted for best throughput performance for a particular stream. The thickness of the second zone can be 10 to 100 μm, with an exemplary preferred thickness of approximately 20 μm.

[0037] The third zone, located between the first two zones, is asymmetric and has a pore size of 0.01-0.8 μm and a thickness of 10-150 μm. To enable pleating of the membrane, the third zone is typically thick, with one preferred thickness being approximately 110 μm. During development of this application, it was found that a symmetric third zone resulted in reduced throughput due to a distinct high-density region at the interface.

[0038] 1A-1B and 2A-2C include SEM micrographs of cross sections of exemplary membranes of the present application, with a first zone at the bottom, a second zone at the top, and a third zone between the first and second zones.

[0039] In a further embodiment of the present application, the membrane has a total thickness of 65 to 300 μm.

[0040] According to the present application, the membrane structure in each distinct zone can be precisely tailored by applying different mix formulations according to membrane performance requirements. Furthermore, each zone has its own characteristic morphology; there is no distinct interface zone between any two adjacent casting zones. The membrane morphology can be varied depending on the different casting formulations and process conditions used.

[0041] The process of the present application provides precise control of the individual zones of the membrane. Typically, a mix with low solids and low viscosity is made for the top zone (first zone), which will provide protection for the underlying retention zone. The second zone is made with a mix of a specific viscosity to achieve proper morphology and significantly increase throughput. The third zone (middle zone) can be made by using a higher viscosity mix to provide retention performance and base capacity. There is no required mix viscosity ranking from the first mix to the third mix, which differs from U.S. Patent No. 5,620,790 to Holzki et al., which is incorporated herein by reference in its entirety. Holzki discloses that the viscosity of each successive zone of a solution of polymeric material is equal to or lower than the viscosity of the previous zone.

[0042] According to the present application, the membrane has a throughput (L / m) of greater than -11.65x + 1088.5, greater than -11.65x + 1188.5, or greater than -11.65x + 1288.5 when measured using whey broth. 2 ) where x is the bubble point (psi).

[0043] In a further embodiment, the membrane has a throughput (L / m) greater than -20.23x + 1369.4, greater than -20.23x + 1469.4, or greater than -20.23x + 1569.4 when measured using EMD soy broth. 2 ) where x is the bubble point (psi).

[0044] When comparing the properties of filtration membranes, fluid permeability and bubble point are most commonly used. As used herein, "permeability" is defined as liters / (m 2 It is defined as the bulk velocity of a fluid flowing through a membrane at a unit pressure difference across a porous structure, commonly measured in psi (·hr·psi). The most common fluids used to measure permeability are air and water.

[0045] As used herein, "bubble point" is defined as the pressure of a gas required to displace a liquid from the largest pores of a porous structure. A sample of the material to be tested is immersed in a liquid that naturally fills the pores in the sample. A gas under pressure is then applied to one side of the sample. Initially, the gas does not flow through the sample because the pores in the sample are filled with liquid. However, as the gas pressure increases, the gas will force the liquid out of the largest pores at a certain level of pressure and the gas will begin to flow through the sample. The pressure at which the gas begins to flow through the sample is known as the bubble point pressure.

[0046] The relationship between the size of a fluid-wetted cylindrical pore and the air pressure (P, the bubble pressure of that cylindrical pore) required to empty it is D=4γcosθ / P where D is the pore diameter, θ is the contact angle, and γ is the surface tension of the wetting liquid. If the measured bubble pressure can be empirically correlated to the size of actual membrane pores, it provides a readily obtainable estimate for the size of actual non-cylindrical pores.

[0047] The bubble point of the membrane was measured using a Capillary Flow Porometer (Model No. CFP-1200AEX) manufactured by Porous Materials, Inc. The test liquid used for the bubble point measurement was isopropanol.

[0048] The breaking strain is defined as the ratio of the elongation of the membrane to its original length at the time when the membrane breaks under stress. The breaking strain of the membrane was tested using a Zwick / Roell Z2.5 instrument. Test samples measuring 1 inch x 4.5 inches were pre-cut from the left (L), center (C), and right (R) positions of the membrane roll. The left and right samples were taken from positions 1 inch away from the edge of the membrane. The test samples were loaded into the Zwick instrument and stretched under stress. The stress-strain curve was recorded until the breaking point. The reported value is the average of the test results of the L, C, and R samples. In further embodiments of all aspects of the present application, the membrane has a breaking strain of at least 25% or at least 30%.

[0049] The membrane's higher breaking strain is advantageous over the prior art. Previously, Millipore Express® membranes with pore size ratings of 0.5 μm and Millipore Express® PLUS 0.2 μm were fabricated for high-throughput applications. However, the breaking strain for the 0.5 μm membrane was <10%, and for the Millipore Express® PLUS 0.2 μm membrane it was <20%, and neither of the two membranes was pleatable.

[0050] The term "polymer" as used herein includes polymer compositions formed from one or more monomers. Representative polymers suitable for forming porous membranes include polyolefins such as polyethylene, polypropylene, polymethylpentene, etc.; polystyrene or substituted polystyrene; fluorinated polymers including poly(tetrafluoroethylene), polyvinylidene fluoride, etc.; polysulfones such as polysulfone, polyethersulfone, etc.; polyesters including polyethylene terephthalate, polybutylene terephthalate, etc.; polyamides including poly(hexamethylene adipamide), poly(phenylene terephthalamide), etc.; polyacrylates and polycarbonates; vinyl polymers such as polyvinyl chloride, and polyacrylonitrile. Copolymers such as butadiene-styrene copolymers, fluorinated ethylene-propylene copolymers, ethylene-chlorotrifluoroethylene copolymers, etc. can also be used.

[0051] The first, second, and third microporous zones of the membrane may be formed from one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymers, methacrylic polymers, and copolymers of acrylic or methacrylic polymers.

[0052] Preferred polymers include, but are not limited to, PVDF, nylons such as nylon 66, polyamides, polyimides, polyethersulfones, polysulfones, polyarylsulfones, PVC, PET, polycarbonates, cellulose, regenerated cellulose, cellulose esters such as cellulose acetate or cellulose nitrate, polystyrene, polyetherimides, acrylic polymers, methacrylic polymers, copolymers of acrylic or methacrylic polymers, or blends of any of the above.

[0053] The polymer mixes of this application typically contain at least one polymer and at least one solvent for the polymer(s). The mixes can contain one or more components that are poor solvents or non-solvents for the polymer(s). Such components are sometimes referred to in the art as "porogens." The mixes are preferably homogeneous. They can optionally contain one or more components that are non-solvents for the polymer. The polymer mixes can be stable over time (achieved by good solvent qualities) or metastable over time. The mixes can also potentially have lower or upper critical solution temperatures. Solvents used include dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetramethylurea, acetone, or dimethyl sulfoxide. A myriad of porogens are used in the art, including formamide, various alcohols, and polyhydric compounds such as water, various polyethylene glycols, and various salts such as calcium chloride and lithium chloride.

[0054] Examples of other additives include surfactants to improve wetting, and polymers that are compatible with the primary membrane polymer used to modify the mechanical properties of the final membrane.

[0055] Membranes can be classified as hydrophilic or hydrophobic. When hydrophilic structures are contacted with water, they spontaneously wet, i.e., the water displaces air from the pores of the structure without the application of an external force. On the other hand, a positive pressure is required for water to enter the pores of a hydrophobic structure and displace the air.

[0056] Examples of surfactants used in the preparation of microporous membranes can be found in U.S. Patent No. 4,290,987 to Soehngen et al., U.S. Patent No. 4,298,666 to Taskier, and U.S. Patent No. 4,501,793 to Sarada, which are incorporated herein by reference in their entirety. Surfactants can be coated onto membranes as is generally known in the art. One such example is disclosed in U.S. Patent No. 3,853,601 to Taskier, which is incorporated herein by reference in its entirety. The disclosed polyolefin-based microporous films, such as polypropylene microporous films, can be made hydrophilic by treatment with a silicone glycol copolymer surfactant. The microporous film can be impregnated with a combination of a silicone glycol copolymer surfactant and a cationic imidazoline tertiary amine. The surfactant is applied to the polyolefin-based microporous film by contacting the film with about 1 to 10 weight percent of a dilute solution of the surfactant(s) and / or surfactants in an organic solvent, such as acetone, methanol, ethanol, or isopropyl, to provide a surfactant "add-on" to the microporous film of about 2 to about 20 weight percent, based on the weight of the uncoated microporous film. The hydrophilic microporous polyolefin-based films produced by this method are said to be rapidly wettable and useful as battery separators.

[0057] U.S. Patent No. 4,501,793 to Sarada, incorporated herein by reference in its entirety, discloses the use of alkylphenoxypoly(ethyleneoxy)ethanol surfactants. The surfactants used have an HLB (hydrophilic-lipophilic balance) of approximately 10-15. Such surfactants are well known to those skilled in the art and are readily commercially available. Suitable surfactants include, for example, the 500 and 600 series compounds sold under the Igepal® trade name by GAF Corporation, such as Igepal® RC-520, RC-620, RC-630, CO-520, CO-530, CO-610, CO-630, CO-660, CO-720, CA-520, CA-620, and CA-630.

[0058] Hydrophilic microporous membranes can be prepared by impregnating a normally hydrophobic polyolefin-based microporous substrate membrane with a solution containing one or more of the aforementioned alkylphenoxypoly(ethyleneoxy)ethanol compounds in a solvent mixture containing about 55-65 volume percent methanol or acetone and about 35-45 volume percent water. Preferably, the solvent system contains about 60 volume percent methanol or acetone (especially methanol) and about 40 volume percent water. A preferred procedure involves immersing the microporous substrate material in the surfactant solution for a time sufficient to produce the desired improvement in hydrophilicity of the polyolefin-based microporous substrate. If necessary, the surfactant solution can be employed in the form of an ultrasonic bath, although this procedure does not appear to be critical to the preparation of the hydrophilic material. Use of the aforementioned solvent system has been found to achieve deeper penetration of the porous structure of the microporous substrate material by the alkylphenoxypoly(ethyleneoxy)ethanol surfactant than can be obtained with other solvent systems that have been used to treat microporous materials.

[0059] The hydrophilic membrane of the present application can be made by blending a hydrophilic polymer(s) into the mix. Examples of hydrophilic polymers are polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, polyoxazoline, etc. Hydrophilic membranes can also be made by further surface modification as described in U.S. Patent No. 4,944,879 to Steuck, which is incorporated herein by reference in its entirety. In this case, no hydrophilic polymer would be added to the casting mix, and a hydrophobic membrane would be made first.

[0060] In another embodiment, the first, second, and / or third microporous zones of the membrane can be hydrophilic. The first, second, and / or third microporous zones can comprise a hydrophilic polymer independently selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl pyridine, polyethylene imine, and polyoxazoline. In a specific embodiment of the present application, the hydrophilic polymer comprises poly(2-ethyl-2-oxazoline). More specifically, the first, second, and / or third microporous zones of the membrane can comprise polyethersulfone and poly(2-ethyl-2-oxazoline). The hydrophilic polymer can be crosslinked, which can be achieved by treatment with an electron beam (e-beam). In an exemplary embodiment of the present application, the hydrophilic polymer is crosslinked by an electron beam having a dose of about 20 to 150 kGy.

[0061] Furthermore, the membrane can include a hydrophilic coating on the membrane. To surface-modify a hydrophobic membrane with a hydrophilic polymer coating, the coating polymer can be directly coated onto the membrane, or can be coated onto a membrane that has already been coated with an intermediate polymer without using a chemical polymerization initiator. If no intermediate polymer is present, a cross-linking agent is added to the monomer that is coated onto the membrane. If an intermediate polymer is used, it functions as a cross-linking agent, and in this case, a separate cross-linking agent is not required.

[0062] When an intermediate coating polymer is utilized, it functions to facilitate coating of the porous membrane with the cross-linking monomer. A solution of the intermediate polymer is applied to the porous polymer membrane. The concentration of the intermediate polymer in the solution is such that it evenly coats the porous membrane without blocking the pores, typically about 1-20% by weight of the solution. The intermediate polymer is then cross-linked by exposure to an electron beam; or alternatively, a polymerizable monomer can be coated onto the porous polymer membrane, and both the intermediate polymer and the monomer can be cross-linked with an electron beam. Suitable intermediate polymers include polybutadiene, polyvinyl chloride, atactic polypropylene, thermoplastic polyurethane, polyamide (nylon 66), polyisobutylene, and the like, which exhibit the ability to graft onto the porous membrane substrate upon exposure to electron beam energy.

[0063] The polymerization and crosslinking of the polymerizable monomer onto the porous membrane must be carried out so that the entire surface of the porous membrane, including the inner surfaces of the pores, is completely coated with the monomer. Therefore, in the first step, the porous membrane is washed with a solvent composition, such as a mixture of water and an organic solvent, that will not swell or dissolve the porous membrane and will wet the surfaces of the pores. Suitable water-solvent compositions for this purpose include methanol / water, ethanol / water, acetone / water, tetrahydrofuran / water, etc. The purpose of this wetting step is to ensure that the monomer composition that subsequently contacts the porous membrane will wet the entire surface of the porous membrane. This preliminary wetting step can be omitted if the reagent bath itself functions to wet the entire surface of the porous membrane. This can be achieved if the reagent bath contains a high concentration of organic solvent, for example, 15% by weight or more.

[0064] The specific solvent used for the polymerizable monomer depends on the specific monomer used and the specific polymer used to form the porous membrane. It is necessary that the monomer dissolves in the solvent and that the solvent does not attack the porous membrane. Therefore, the specific solvent system used depends on the monomer and porous membrane used. Typical suitable solvents include water or organic solvents such as alcohols, esters, acetone, or compatible aqueous mixtures thereof.

[0065] Generally, the polymerizable monomer to be coated onto the membrane is present in the reaction solution at a concentration of about 0.1% to about 20%, preferably about 0.5% to about 1%, based on the weight of the reaction solution. When a crosslinker other than the intermediate polymer is used, the crosslinker is present at a concentration of about 0.1% to about 20% based on the weight of the monomer.

[0066] The following procedure describes a general method for producing a modified membrane surface. The membrane to be treated is wetted with methanol, rinsed with water, and immersed in an aqueous monomer / crosslinker solution for several minutes to ensure complete exchange. If the monomer / crosslinker solution can directly wet the membrane, the pre-wetting exchange step is not necessary. The wet membrane is sandwiched between sheets of polyethylene and gently pressed with a rubber roller to achieve uniform loading of the monomer / crosslinker solution, then exposed to the e-beam. The pressed membrane is removed from the polyester sandwich and taped to a new sheet of polyester, which is then taped to the polyester carrier belt of the pilot coater / laminator and electron beam processor. The electron beam processor is set to deliver the desired dose and maximum current required for crosslinking. After the desired dose is delivered, the treated membrane is rinsed with water and / or methanol to remove unreacted and oligomeric material. The membrane is then dried and tested for rewet, flow, and other properties.

[0067] Another aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane, wherein the membrane has a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric, and the third microporous zone is disposed between the first and second microporous zones, and the first, second, and third microporous zones are integral with one another. Further, the first, second, and / or third microporous zones comprise a blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and copolymer of acrylic or methacrylic polymer, and a second polymer, wherein the second polymer is selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. The membrane has a breaking strain of at least 20% and a throughput (L / m) of greater than -11.65x + 1088.5 as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0068] In another embodiment, the first polymer is PES and the second polymer is poly(2-ethyl-2-oxazoline). Furthermore, the membrane may be crosslinked. In a more specific embodiment of the present application, the first polymer is PES, the second polymer is polyoxazoline, and the membrane is crosslinked by electron beam irradiation. The membrane may be crosslinked by electron beam irradiation with a dose of about 20 to 150 kGy.

[0069] In a further embodiment of the present application, the membrane can be pleated without loss of membrane retention. In more specific examples of all aspects of the present application, the membrane is pleated.

[0070] As used herein, the terms "pleat" or "pleated" are intended to include all such cross-sectional shapes. Relative to the occupied volume, pleated structures present a greater surface area to the incoming fluid process flow than would be presented by the use of a flat sheet. This is particularly advantageous in view of the desire to maximize device throughput.

[0071] The membrane pleats can be configured in a corrugated or spiral configuration and can have a looped or folded cross section, such as a W-shaped or M-shaped cross section. Pleated membranes are typically wrapped around their longitudinal axis, with the ends of the pleated membrane sealed together to form a tubular structure or filter tube. In another embodiment, the pleated membrane is sealed within a frame that is sealed to its periphery as a flat-corrugated filter. In all embodiments, the pleated membrane is designed so that liquid or gas must pass through it to pass downstream.

[0072] The retention properties of membranes can be tested using the ASTM F838-15 Bacterial Retention Test Method, which uses worst-case processing conditions to determine whether a sterilizing-grade filter can retain a 1 cm filter area. 2 10 per 7This test determines the ability of cells to retain a minimum challenge of Brevundimonas diminuta (B. diminuta). Size controls are performed with each test to verify that the test organism is of the appropriate size. For devices made with 0.2 μm pore-size-rated membranes, it is important that the device retains its full capacity when challenged with a B. diminuta solution. If the membrane is too weak, cracks may form during the membrane pleating process. As a result, high diffusion rates are observed within the device, resulting in a non-retentive device. Crack formation during pleating increases the probability that microorganisms such as B. diminuta can pass through the cracks, thus causing a decrease in retention, or "degraded" membrane retention.

[0073] A second aspect of the present application relates to a filtration cartridge comprising a housing and a membrane of the present application disposed within the housing. The filtration cartridge can include the membrane of the present application in the form of a filter tube. In one embodiment of the present application, the membrane of the filter cartridge is pleated. In another embodiment, the filter is spirally wound in one or more layers, with or without spacers between them. Furthermore, the cartridge can have a membrane thickness of 0.11 m per inch of housing height. 2 The membrane may contain an effective membrane area of ​​greater than 1000 sq. m.

[0074] An example of a filter cartridge of the present application is shown in Figure 3. The filter cartridge 2 of Figure 3 includes a pleated high-throughput membrane 4 of the present application, which surrounds a porous hollow core 6 and is provided with a sealing cap 8 and a second cap 10 having an outlet 12. Optionally, an outer porous protective cage (not shown) is spaced from and surrounds the outer surface of the membrane. Preferably, the cage is sealed to the sealing cap 8 and second cap 10 to form an integrated cartridge filter. The cage, when used, maintains the membrane in a relatively fixed, tubular conformation. The cage may be made of a rigid material and have uniformly distributed pores, allowing inward flow of fluid from the peripheral region of the pleated filter tube, through the membrane, into the core 6, and then ultimately out the second end cap 10 via the outlet 12.

[0075] Further details regarding the structure and function of replaceable filter cartridges are provided in U.S. Patent No. 5,736,044 to Proulx et al. The pleated filter element can be utilized alone or in conjunction with a prefilter. The prefilter may be positioned within the housing adjacent the fluid inlet or applied to the cartridge adjacent the outer surface of the membrane.

[0076] A filter cartridge typically contains a porous filtration element located within a structural housing. In such filters, unfiltered fluid enters the housing through an inlet port and passes through the filtration element, which removes contaminants and other impurities from the fluid. The filtered fluid is discharged through an outlet port. Filter cartridges typically include so-called "quick-change" cartridges, in which the inlet and outlet are combined into a single port at one end of the housing, and in-line cartridges, in which the inlet and outlet ports are located at opposite ends of the housing. Because fluid flow is often pressurized, these ports are typically sealed, for example, with O-rings. Therefore, providing small ports is desirable because larger openings are more difficult to seal (the larger the seal, the greater the force it will experience for a given pressure).

[0077] The housing can be constructed as one piece or as two or more components structurally attached together into an assembly. Using a one-piece housing can reduce costs compared to multi-piece assemblies. Polymer one-piece housings can be manufactured by any suitable process, including gas- or water-assisted blow molding or injection molding. Blow molding is generally faster and less expensive than injection molding. Blow molding also stretches and aligns the polymer chains, resulting in stronger and more resilient material properties compared to injection molding. Either process can produce hollow containers, such as plastic bottles, with interiors that have dimensions larger than the desired mouth or port size at the connecting end. Alternatively, the housing can be made of metal and fabricated by casting or rotational molding. While one-piece construction offers cost benefits, the housing can also be manufactured as a two-piece (or more) assembly of injection-molded or cast components.

[0078] The filter tube, preferably pleated, is comprised of at least one layer of the high-throughput membrane of the present application. Preferably, the membrane is oriented so that fluid introduced into the housing through the fluid inlet begins its passage through the asymmetric membrane through the open side. Figure 4 illustrates one such design. A cartridge 2 is disposed within a housing 14. The fluid to be filtered, whether liquid or gas, enters the interior of the housing 14 through a first or inlet port 16, as indicated by arrow 26. The fluid passes through the outer surface 18 of the cartridge 2, into the core (not shown), as indicated by arrows 20 and 22, and out the second port 12 or outlet of the housing 14, as indicated by arrow 24. If desired, the fluid flow can be reversed, with the second port 12 functioning as the inlet and the first port 16 functioning as the outlet. From the second port 12, the fluid can flow through the core and membrane (not shown), past the outer surface 18 of the cartridge 2, into the interior of the housing 14, and out through the first port 16.

[0079] A further aspect of the present application relates to a filtration cartridge including a housing and a pleated membrane disposed within the housing, wherein the membrane has a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric, and the third microporous zone is disposed between the first and second microporous zones, with the first, second, and third microporous zones integral with one another. The first, second, and / or third microporous zones comprise a blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and copolymer of acrylic or methacrylic polymer, and a second polymer, wherein the second polymer is selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. The membrane has a breaking strain of at least 20% and a throughput (L / m) of greater than -11.65x + 1088.5 as measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi); and wherein the housing has a flow rate of 0.11 m per inch of housing height. 2 It includes an effective membrane area of ​​over 1000m.

[0080] A further aspect of the present application relates to a process for forming a multi-zone, microporous, high-throughput filtration membrane having a strain at break of at least 20%. The process includes providing a solution of a polymer and a solvent for the polymer, simultaneously or sequentially casting the solution onto a support as three separate zones to form a multi-zone liquid sheet, allowing phase separation of the solution of the three separate zones, and separating the multi-zone, microporous, high-throughput filtration membrane from the support. The membrane includes a first microporous zone, which may be symmetric or asymmetric, a second microporous zone, which may be symmetric or asymmetric, and a third microporous zone, which may be asymmetric, wherein the third microporous zone is disposed between the first and second microporous zones. The first, second, and third microporous zones are integral with one another, and the membrane has a throughput (L / m2) greater than -11.65x + 1088.5 as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0081] In one embodiment of the process for forming a high-throughput multi-zone membrane, the solution includes at least one polymer and at least one solvent for the polymer. The solution may have an upper critical solution temperature or a lower critical solution temperature. Furthermore, the solution may further include one or more porogens, such as formamide, alcohol, polyhydric compounds, water, polyethylene glycol, calcium chloride, and lithium chloride. The process for forming a high-throughput multi-zone membrane may further include coating a hydrophilic substrate onto the membrane.

[0082] High-throughput multi-zone membrane casting can be performed sequentially. Additionally, casting can be performed simultaneously, such as by co-casting.

[0083] In another aspect, the membrane formation process includes phase separation, which is effected by heating the solution above its lower critical solution temperature. Phase separation can also be effected by vapor-induced phase separation.

[0084] In forming a multizone membrane, different mixes for different zones can be formed by varying the concentration of polymer, solvent or non-solvent, and solution viscosity, additives or treatments, or any combination thereof, to create the desired multizone structure.

[0085] The selection of a solvent to provide a stable homogeneous solution for casting in membrane formation involves the basic principle of polymer solubility. Polymer solvents can be classified as good solvents, non-solvents, and poor solvents. A good solvent is one in which the interaction (force) between the polymer molecules and the solvent molecules is greater than the attractive force between one polymer molecule and another. The opposite is true for non-solvents. A poor solvent is one in which the interaction between the polymer and the solvent is equal to the attractive force between one polymer and another.

[0086] Generally, zones of a multi-zone structure can be formed from the same polymer and solvent by varying the concentration of components in the mix, viscosity, additives, and processing (before, during, or after formation), or different polymers can be used for different zones. If different polymers are used, compatible polymers must be selected. Furthermore, the solvent and phase-separation material should be the same, if possible, or at least compatible, so as not to adversely affect other zones.

[0087] There are several processes for preparing porous polymer structures. The most common process is based on phase separation of a polymer solution. In such processes, the composition or temperature of the polymer solution is changed so that it becomes thermodynamically unstable and separates into two phases. One phase, containing most of the solvent components, is then removed, and the other phase, containing most of the polymer, becomes the porous structure. The types of phase separation processes typically fall into three categories: 1) vapor-induced phase separation (VIPS), also known as "dry casting" or "air casting," 2) liquid-induced phase separation (LIPS), primarily known as "immersion casting" or "wet casting," and 3) thermally induced phase separation (TIPS), often referred to as "melt casting."

[0088] The VIPS and LIPS processes rely on mass transfer between the components of the cast polymer solution, or mix, which exists in the vapor or liquid state, and the precipitant medium, respectively. TIPS is controlled by temperature changes in the polymer solution. The VIPS process has an inherent drawback: low mass transfer rates, which require long residence times in the casting machine, resulting in a trade-off between expensive long-run machines and slower throughput. The LIPS process runs at relatively high speeds due to the higher mass transfer between the polymer solution and the liquid precipitant. This is an advantage in the LIPS process, which is used to manufacture ultrafiltration and reverse osmosis membranes, which require high mass transfer rates to create small pore sizes. However, it presents a complication in processes for creating microporous structures, which typically require moderate mass transfer rates to allow sufficient growth of the dilute phase, resulting in larger pore sizes in the microporosity range of 0.05 to 10 micrometers. Several methods have been devised in the prior art to overcome this complication for creating microporous structures using the LIPS process. One common method is to use a high content of organic solvent, as described in U.S. Patent No. 4,203,847 to Grandine and U.S. Patent No. 4,340,479 to Pall, which are incorporated herein by reference in their entireties, or neat organic solvent in an immersion bath. This principle was well analyzed by Wijmans et al., J. Membr. Sci., 14, 263 (1983), which is incorporated herein by reference in its entirety. The drawbacks of this technique are the use of large amounts of flammable organic liquid, which requires explosion-proof manufacturing facilities, and the high cost of solvent disposal.

[0089] As taught in U.S. Patent No. 5,444,097 to Tkacik, the entirety of which is incorporated herein by reference, membranes are made from polymer mixes that exhibit a lower critical solution temperature ("LCST") as measured by cloud point. Heating the mix above the LCST causes phase separation. This phase separation step is incorporated into the process of the present application for membrane pore size control. A vapor-induced phase separation step has also been incorporated into the present application. Dew point and vapor temperature affect the membrane pore formation process, allowing pore size to be controlled accordingly.

[0090] The process of the present application utilizing the LCST process begins with preparing a homogeneous mix of at least one polymer in a solvent system, the solvent system consisting of at least one component that is a solvent for the polymer, where the homogeneous solution exhibits a lower critical solution temperature. The homogeneous mix may optionally contain one or more components that are non-solvents for the polymer. The mixed solution can be prepared by conventional means, mixing the polymer and the components of the solvent system together. The polymer mix is ​​then molded into a desired shape. The molded mix is ​​heated until phase separation occurs, characterized by cloudiness of the solution. The components of the solvent system are then removed by methods such as evaporation or extraction. The conditions of the removal process can further affect the later stages of phase separation and the properties of the polymer porous structure. A preferred method for removing the components of the solvent system involves immersing the molded phase-separated polymer mix in one or more liquid baths containing at least one non-solvent for the polymer, where the non-solvent is miscible with at least one component of the solvent system. The porous polymer structure can then optionally be subjected to further extraction or drying.

[0091] As taught in U.S. Patent No. 7,842,214 to Romdhane et al., which is incorporated herein by reference in its entirety, vapor-induced phase separation (i.e., air casting) generally involves a coagulating agent (e.g., water vapor) to induce phase inversion. The coagulating agent can be introduced as a vapor into the polymeric material of the membrane. High concentrations of vapor can condense and reduce the thermodynamic stability of the polymeric material dissolved in the solvent. Similar to liquid-induced phase separation, polymer-rich and polymer-poor regions form from vapor-induced phase inversion, resulting in the formation of a microstructure. Examples of coagulating agents for vapor-induced phase separation include water, alcohols, amides, and combinations thereof.

[0092] Contact between the polymer and coagulant vapor at the surface and diffusion of some of the coagulant into the polymer solution can cause the polymer material to become thermodynamically unstable. The polymer material can precipitate from the solution solvent and form microstructures. During phase inversion, regions of the polymer solution zone are rich in polymer material and form structures, while some regions are poor in polymer material and form pores. After the development of microstructures, the membrane may be further subjected to solvent removal and subsequent drying.

[0093] After the polymer mixes are made, they are applied to a moving carrier. For unsupported membranes, where no web is attached to the final membrane, the carrier is usually a plastic film, such as polyethylene terephthalate, or polyethylene-coated paper, or similar smooth, continuous web that can be easily removed from the formed membrane.

[0094] In one embodiment of the present application, the membrane is fabricated via a slot co-casting process. "Co-casting" refers to the fact that individual zones are cast onto one another essentially simultaneously, with no substantial time interval between one cast zone and the next. Co-casting is an important aspect of the present application because it allows for the formation of controlled pore size regions at the junctions of the zones. Other casting techniques known in the prior art create clearly defined boundaries between successive cast zones. The dramatic change in pore size, from a more open to a denser structure, can lead to undesirable rapid particle accumulation at the interface and / or the formation of thin film zones at the interface, resulting in a dramatic flux reduction. Perhaps due to partial mixing of adjacent co-cast lacquers or high shear forces at the interface between two adjacent co-cast lacquers, the sharp interface can be replaced by a more subtle change in pore size between the two adjacent zones. Such an interfacial zone is beneficial to the membrane's overall structural integrity. At the same time, it allows for the formation of a microporous structure without discernible boundaries within the structure.

[0095] The polymer mixes can be applied by any standard method. The goal is to coat the first mix solution onto the carrier, the second mix solution onto the first mix solution, and the third mix solution onto the second mix solution. A preferred method is co-casting, which is described in detail in U.S. Patent No. 8,123,992 to Kools, which is incorporated herein by reference in its entirety. Co-casting can be performed using a triple-slot die-over-roll apparatus, a pressurized tri-slot coating bead, or any other pre-metered or post-metered coating device known in the industry. Co-casting generally allows for the formation of controlled pore size regions at the junctions of the zones; however, even with the co-casting technique, sharp or well-defined boundaries between zones can be formed, if desired, by appropriate selection of the formulation and application methodology.

[0096] Figure 5 illustrates a multiple-zone forming apparatus 28 for casting multi-zone membranes. As shown, the apparatus 28 is designed to produce a three-zone liquid film and has three chambers 30, 32, and 34 containing solutions A, B, and C (one for each zone) to be cast. Additional chambers may be added to form additional co-casting zones as needed. The apparatus includes a front wall 36 and a rear wall 42, with dividing walls 38 and 40 between the front and rear walls. The dividing walls define the volumes of the three chambers. Two side walls complete the apparatus. In operation, the apparatus is fixed on a typical membrane casting machine, and a support web 50 moves or passes under the fixture, dispensing the three solutions through gaps or outlets 44, 46, and 48. The thickness of the zones is controlled by the distance (gap) set between the moving web and the outlet, indicated by gap settings 44, 46, and 48. The final liquid layer thickness is a function of the gap distance, solution viscosity, and web speed. The back wall of the apparatus is usually held a short distance above the support to prevent wrinkling or damage to the support. The back wall gap, support speed, and solution viscosity are adjusted in practice to prevent the solution from leaking through the back wall gap. The apparatus can be fitted with heating or cooling means, either for each chamber separately or for the entire apparatus, as required by solution properties or to further control the final film properties.

[0097] A slot die consists of an enclosed reservoir with an exit slot of a smaller cross section. An extruder or positive displacement pump, or sometimes a pressurized vessel, delivers the coating at a uniform rate into the reservoir, forcing all fluid entering the die out of the reservoir through the slot and onto the moving carrier web. The slot is positioned perpendicular to the moving carrier web. Multiple zone coating requires a die with individual reservoirs, associated feed methods, and an exit slot for each zone.

[0098] The membranes of the present application can be manufactured using a pre-metered coating process, in which the exact amount of coating solution to be deposited is directed to the coating head. The zone height is set by deposition, rather than by some post-application means, such as a doctor blade, which sets the structure thickness after metering the zone (commonly referred to as a "post-metering process"). The term pre-metering applies to die coating, slide and curtain coating, among other methods of forming structures.

[0099] After the zones are coated onto the moving carrier, the nascent film is immediately exposed to the environment of a controlled air chamber. Thermally induced phase separation can be initiated by controlled drum temperature, and moisture-induced phase separation can be initiated by moisture absorbed from the air chamber. The nascent film is then immersed in a liquid that is a non-solvent for the polymer and miscible with the solvent and porogen. This causes non-solvent-induced phase separation and ultimately the formation of a porous film. One example of a liquid that can be used as a non-solvent for the nascent film is water.

[0100] The formed membrane is then typically separated from the carrier and washed to remove residual solvent and other materials. The membrane can then be dried. Water can be used to wash the membrane, and the membrane can be dried in a vacuum drum dryer.

[0101] In the coagulation of a multi-zone liquid sheet, coagulation occurs first at the liquid film surface that contacts the coagulation bath, then through subsequent zones of the multi-zone liquid sheet. Each zone dilutes and alters the coagulant as it diffuses through the zone. These changes to the coagulant properties affect the membrane formation in each zone and in the final multi-zone membrane. The thickness, composition, and location of each zone relative to the other zones affect membrane structure and properties. Each zone forms differently than would be formed if made from a single-zone solution or a stack of single zones.

[0102] In another embodiment, the zones are cast sequentially onto a preceding cast. In sequential casting, solutions containing polymers are typically cast one on top of the other into thin films, followed by quenching in a non-solvent for the polymer. The first solution is spread in a zone (lower zone) on a support (such as a non-porous support), the second solution is spread in a zone (upper zone) on the first solution, and so on. The membrane can later be separated from the support after quenching; however, the support (porous or non-porous) can be incorporated into the final structure as needed.

[0103] The film can be cast manually (e.g., by manually pouring, casting, or spreading the solution onto a casting surface and quenching the liquid applied to the surface) or automatically (e.g., by pouring or otherwise casting onto a moving bed). There should be a time interval between castings of the solution. Preferably, the time interval is about 2 seconds or more. For example, the time interval can be within a range of about 2 seconds to about 35 seconds, or about 2 seconds to about 10 seconds.

[0104] Various devices known in the art can be used for casting. Suitable devices include, for example, mechanical spreaders, including coating knives, doctor blades, or spray / pressure systems. One example of a spreading device is an extrusion die or slot coater, which includes a casting chamber into which the casting formulation (a solution containing a polymer) can be introduced and extruded under pressure through a narrow slot.

[0105] The support with the casting solution thereon is then immersed in a quench bath, resulting in phase separation of the polymer solution. In the quench bath, precipitation or coagulation occurs first from the liquid film surface contacting the bath, then through subsequent zones. After formation, the membrane is typically washed (e.g., in deionized water) to remove residual solvent and then dried.

[0106] Another aspect of the present application relates to an unsupported, microporous, high-throughput filtration membrane having a breaking strain of at least 20% and a bubble point (psi) of about 15 to 50. The membrane has a throughput (L / m2) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or when using EMD soy broth, has a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi). This aspect of the application can be implemented using the features discussed above with respect to the other high throughput filtration membrane embodiments of the application.

[0107] A further aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a symmetric first microporous zone, an asymmetric second microporous zone, and an asymmetric third microporous zone. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0108] An additional aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a symmetric first microporous zone, a symmetric second microporous zone, and an asymmetric third microporous zone. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0109] Another aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes a first microporous zone that is asymmetric, a second microporous zone that is symmetric, and a third microporous zone that is asymmetric. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0110] A further aspect of the present application relates to a multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of about 15-50 and a strain at break of at least 20%. The membrane includes an asymmetric first microporous zone, an asymmetric second microporous zone, and an asymmetric third microporous zone. The first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones. The membrane has a throughput (L / m²) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0111] Another aspect of the present application relates to an unsupported, microporous, high-throughput filtration membrane having a breaking strain of at least 20% and a bubble point (psi) of about 15 to 50. The membrane has a throughput (L / m2) greater than -11.65x + 1088.5, as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1369.4, where x is the bubble point (psi).

[0112] A final aspect of the present application relates to an unsupported, microporous, high-throughput filtration membrane having a breaking strain of at least 20% and a bubble point (psi) of about 15 to 50. The membrane has a throughput (L / m) greater than -11.65x + 1188.5 as measured using whey broth. 2 ), where x is the bubble point (psi), or with EMD soy broth, have a throughput greater than -20.23x + 1469.4, where x is the bubble point (psi).

[0113] Preferences and options for any given aspect, feature, embodiment, or parameter of the technology described herein should be considered as disclosed in combination with any and all preferences and options for all other aspects, features, embodiments, and parameters of the technology, unless the context dictates otherwise.

[0114] The following examples are presented to illustrate various aspects of the present application, but are not intended to limit the scope of the claimed invention. [Example]

[0115] material and method Membrane performance, including permeability, bubble point, thickness, and breaking strain, was tested after the membrane casting process was completed. Permeability was calculated by measuring the water flow through a 47 mm membrane disk under vacuum. Membrane bubble point was tested using isopropanol in a bubble tester. The two challenge streams selected for membrane throughput testing included EMD soy and whey, and an OptiScale® 25 device was used for the testing. Detailed throughput testing procedures are described in Sal Giglia et al., "Scaling Considerations to Maximize the High-Area Advantage," Bioprocess International, 15(5): 42-45 (2017), which is incorporated herein by reference in its entirety.

[0116] Bubble Point Test 25 mm membrane disks were die cut and isopropanol was used as the wetting agent for membrane bubble point testing, which was performed using a Capillary Flow Porometer (CFP-1200 / AEX) manufactured by Porous Materials, Inc.

[0117] Breaking Strain Test Membrane sample strips measuring 1 inch x 4.5 inches were cut from the left, center, and right sides of the membrane roll, and the breaking strain was measured using a Zwick / Roell Z2.5 instrument. Test samples were pre-cut from the left (L), center (C), and right (R) positions of a 10-inch-wide membrane roll. Left and right samples were taken 1 inch from the edge of the membrane roll. The reported values ​​are the average of the test results for the L, C, and R samples. Tests were conducted at 23°C and 18-25% relative humidity. A load of 0.98 Newtons (N) was used to check the performance of the load cell, and the preload was 0.05 N throughout the test. Flat grips were used with a grip pressure of 30 psi, and the distance between the two grips was 1.5 inches. The test speed was 2 inches per minute. Data were collected as the membrane was stretched to its breaking point.

[0118] EMD Soybean Challenge Stream The EMD soy solution used in the throughput test was prepared as follows: 5.0 liters of reverse osmosis (RO) water was measured out using a graduated cylinder, and 4.0 L of it was added to a 10 L plastic bucket. 67 g of Hyclone dry powder Dulbecco's Modified Eagle's Medium (DMEM) was added to the 4.0 L of water, using some spare RO water to rinse the DMEM container into the bucket. The solution was then covered and mixed with a large stirrer at 300 rpm for 20 minutes. 18.5 g of sodium bicarbonate was added to the solution, and the weigh boat was rinsed with spare RO water. The solution was covered and mixed for 5 minutes. 5.0 g of Pluronic F-68, also known as Kolliphor, was added to the solution, and the weigh boat was rinsed with spare RO water. The solution was covered and mixed for 20 minutes. EMD soy was added from pre-measured test tubes (containing 10 g), and these were rinsed with the remaining RO water. The solution was covered and mixed for 65 minutes, after which the stirring was stopped, the stir bar was removed, and the solution was poured into a clean 5 L pressure vessel. Throughput testing began within 1 hour of completing the solution preparation.

[0119] Whey Challenge Stream The whey solution used in the throughput test was prepared as follows: PBS buffer was prepared using RO water. In a 10 L batch, 1000 mL of 10x PBS Liquid Concentrate (Calbiochem OmniPur, Part # 6507) was added to 9.0 L of RO water. The solution was thoroughly mixed with an impeller (Cole Parmer Stir-Pak Laboratory Mixer Model 04555-00) at setting 3 for at least 1 minute. Whey (Sigma Part # W1500, lightly spray-dried bovine whey) was added to the mixed buffer to obtain a concentration of 0.3 g / L and mixed for 20 minutes. The throughput test began within 2 hours of making the whey solution.

[0120] Throughput Test Two challenge streams were used in this study, both of which are listed in Table 1. These streams exhibited small and medium particle sizes and particle size distributions. The particle size distributions of these streams are plotted in Figure 6. Severe clogging (<1000 l / m) occurred within approximately 60 minutes at the test process conditions. 2 The challenge stream was concentrated to achieve >90% flux decay in the filtrate. Throughput data were recorded when flux decay reached 90%.

[0121] Table 1: List of challenge streams for throughput testing TIFF0007824215000001.tif31155

[0122] Testing was performed as disclosed by Giglia et al., "Scaling Considerations to Maximize the High-Area Advantage," Bioprocess International, 15(5): 42-45 (2017), which is incorporated herein by reference in its entirety. Membranes were first tested using an OptiScale® 25 instrument for clean water permeability at 10 psi (690 mbar) at a temperature of 21-25°C. Following the water permeability test, a throughput test was performed using either an EMD soy stream or a whey stream, conducted at 10 psi (690 mbar). The throughput test was performed until the membrane permeability was reduced by at least 95% compared to the clean water permeability. Graphical data of throughput versus bubble point can be seen in Figures 7 and 8. The dotted lines in Figures 7 and 8 were constructed using the average throughput data for both the Millipore Express® SHC and SHRP systems collected in all examples. A Millipore Express® SHC scaling OptiScale®-25 device was used in all throughput test batches as an internal standard. Individual sample throughput (Tput) was calculated according to the following formula: Tput = Tput ratio * Average Tput(SHC) where Tput ratio is the ratio of the individual sample throughput to the Millipore Express® SHC throughput collected in the individual test batch, and Mean Tput(SHC) is the average Millipore Express® SHC throughput data collected across all examples.

[0123] Example 1 - Hydrophilic triple-zone membrane Hydrophilic triple-zone membranes with bubble points ranging from 16.8 psi to 23.8 psi were developed by triple slot casting by blending the hydrophilic polymer PEOX (Aquazol-500, Polymer Chemistry Innovations, Inc.) into the mix. The throughput of these membranes is at least 130% of that of the commercially available Millipore Express® SHC.

[0124] Three mixes, including one top, one middle, and one bottom, were prepared according to the formulation in Table 2. The formulations included polyethersulfone (PES, SUMIKAEXCEL PES 5200P), N-methyl-2-pyrrolidone (NMP), triethylene glycol (TEG), and PEOX. The mix viscosity was tested using a Brookfield viscometer (LVDV-II +P) after thoroughly degassing the mix. Viscosity and cloud point data are further displayed in Table 2. Six membrane samples (Membranes 1A-1F) were prepared using a triple slot casting process at various drum temperatures (see Table 3) for different bubble points. The top mix flow rate was 1.4 L / h, the middle mix flow rate was 12.6 L / h, and the bottom mix flow rate was 1.9 L / h. The nascent membranes initiated phase separation while on the drum, exposed to humid air. The process conditions for the formation of Membranes 1A-1F are listed in Table 3, for reference. The nascent membranes were solidified in a forming bath (water) and then extracted in hot water. The membranes were then dried before performance testing. Membrane performance, including bubble point, flow time, thickness, breaking strain, and throughput, is shown in Table 4. The membrane throughputs are all greater than 138% of Millipore Express® SHC. Furthermore, significantly higher EMD soybean throughput (>170% of Millipore Express® SHC) can be achieved when the bubble point is approximately 17 psi. The breaking strain of the membranes (1A-1F) is at least 30%.

[0125] Table 2: Mix formulation of Example 1 film with cloud point and viscosity data TIFF0007824215000002.tif43128Note: Viscosity measurements were performed at 25°C using an S62 spindle at 3 rpm.

[0126] Table 3: Casting conditions for Example 1 membranes (membranes 1A-1F) TIFF0007824215000003.tif50154

[0127] (Table 4) Membrane performance of Example 1 membranes (membranes 1A to 1F) TIFF0007824215000004.tif57153

[0128] Example 2 - Triple-zone membrane with hydrophilic coating Hydrophobic triple-zone membranes were fabricated via triple slot casting and then e-beam modified to add a hydrophilic surface as described in U.S. Patent No. 4,944,879 to Steuck, which is incorporated herein by reference in its entirety. Throughput for these membranes was greater than 130% of the commercially available Millipore Express® SHC.

[0129] A mix was made according to the formulation as shown in Table 5, similar to that of Example 1, but without the addition of PEOX. The mix viscosity was tested with a Brookfield viscometer (LVDV-II +P) after thoroughly degassing the mix. Both the mix viscosity and cloud point data are shown in Table 5. This mix viscosity is significantly lower when compared to the mix of Example 1 (see Table 2) because no PEOX was added.

[0130] Table 5: Mix formulation of Example 2 membrane with cloud point and viscosity data TIFF0007824215000005.tif43128Note: *Viscosity measured at 25°C with an S62 spindle at 1.5 rpm; all other measurements made at 25°C with an S62 spindle at 3 rpm.

[0131] A triple slot die was used during the casting of two membranes (Membranes 2A-2B). The top mix flow rate was 2.8 L / hr, the middle mix flow rate was 30.7 L / hr, and the bottom mix flow rate was 5.6 L / hr. The membrane formation process was very similar to that of Example 1. The different process conditions are disclosed in Table 6 for both Membranes 2A and 2B. Before the membrane entered the forming bath and precipitated, the membrane bubble point was adjusted by changing the casting drum temperature and air exposure conditions. The line speed was set at 30 fpm. The different process conditions are disclosed in Table 6 for both Membranes 2A and 2B. Water was used in the forming bath at 64.8°C. The resulting hydrophobic membranes were recovered after extraction in hot water and drying.

[0132] The dried hydrophobic membrane was pre-wetted with an aqueous solution containing 0.8 wt% N,N'-methylenbisacrylamide and 10 wt% hexylene glycol at room temperature. The pre-wetted membrane was e-beam (PCT Broadbeam electron beam processor, Comet AG) modified with a dose of 25 kGy and rinsed with methanol and then water. The hydrophilic membrane was allowed to dry before performance testing.

[0133] Table 6: Casting conditions for Example 2 membranes (membranes 2A-2B) TIFF0007824215000006.tif34153

[0134] Membrane performance was tested as shown in Table 7 and showed that the permeability of both Membrane 2A and Membrane 2B was approximately 129-140% of that of Millipore Express® SHC.

[0135] Table 7. Performance of Example 2 Membranes (Membranes 2A-2B) and Comparison with Millipore Express® SHC Membranes TIFF0007824215000007.tif41158

[0136] To directly compare the throughput of current commercially available membranes, a Millipore Express® SHC-scaled OptiScale® 25 device was included in the throughput study. The EMD soybean throughput for Membranes 2A and 2B was 135–137% of that of the Millipore Express® SHC, and the whey throughput was 132–142% of that of the Millipore Express® SHC. The membrane rupture strain for both Membranes 2A and 2B was greater than 30%, which is empirically required for good pleated device performance. SEM images of the membrane cross sections for Membranes 2A and 2B are shown in Figures 1A and 1B, respectively. In both cases, there is a clear interface between Zone 1 (the lower zone) and Zone 3 (the middle zone), and no clear interface between Zone 3 (the middle zone) and Zone 2 (the upper zone).

[0137] Example 3 - Hydrophilic triple-zone membrane Hydrophilic triple-zone membranes were fabricated via triple slot casting by blending PEOX (12 wt% of PES) into the PES mix. The throughput for these membranes is at least 120% of that of the commercially available Millipore Express® SHC membrane.

[0138] Three mixes, including one top, one middle, and one bottom, were made according to the formulations in Table 8. All three mixes were tested. Both viscosity and cloud point data are further shown in Table 8. A triple slot die was used for casting, with the top mix flow rate set at 2.5 L / h, the middle mix flow rate at 29.0 L / h, and the bottom mix flow rate at 5.0 L / h. The casting process conditions disclosed in Table 9 and the same process steps as described in Example 1 were followed. Eight membrane samples (Membranes 3A-3H) were made by varying the drum temperature for different bubble points as shown in Table 9. Membrane performance, including bubble point, flow time, thickness, and break strain, was tested as shown in Table 10. Membrane throughput was tested alongside a Millipore Express® SHC scaling OptiScale® 25 mm device as a control. Membranes 3A-3H throughput was at least 120% of that of the commercially available Millipore Express® SHC, and their break strain was greater than 30%.

[0139] Table 8: Mix formulation of Example 3 membrane with cloud point and viscosity data TIFF0007824215000008.tif43128Note: *Viscosity measured at 25°C with an S62 spindle at 1.5 rpm; all other measurements made at 25°C with an S62 spindle at 3 rpm.

[0140] Table 9: Casting conditions for Example 3 membranes (membranes 3A to 3H) TIFF0007824215000009.tif53147

[0141] (Table 10) Membrane performance of Example 3 membranes (membranes 3A to 3H) TIFF0007824215000010.tif65150

[0142] By adding more PEOX to the membrane, an increase in breaking strain can be achieved when compared to the membrane of Example 1 (see Table 4).

[0143] Figures 2A-2C contain SEM micrographs of the cross sections of Membranes 3A, 3C, and 3F, respectively. Clearly, there is no interfacial zone between adjacent zones created by applying triple slot casting. Zone 3 (the middle zone) is asymmetric and is the primary zone contributing to retention performance. Zone 2 (the upper zone in Figure 2) is highly porous and is a unique zone for improved throughput compared to current Millipore Express® membranes, while Zone 1 is the lower zone. Unlike Membranes 3A (Figure 2A) and 3F (Figure 2C), there is a boundary between Zone 2 (the upper zone) and Zone 3 (the middle zone) in Membrane 3C (Figure 2B).

[0144] Example 4 - Hydrophilic triple-zone membrane The goal of this example is to create hydrophilic PEOX / PES triple-zone membranes with much tighter pore sizes. The hydrophilic membranes were further modified by e-beam irradiation at a dose of 50 kGy. The throughput of these new membranes is at least 130% of that of the commercially available Millipore Express® SHRP.

[0145] The formulations for the top, middle, and bottom mixes, along with their properties including viscosity and cloud point, are listed in Table 11. Four different formulation sets were used to make 24 membranes (Membranes 4A-4X). A triple slot die was used for casting, with the top mix flow rate of 2.8 L / h, the middle mix flow rate of 33.7 L / h, and the bottom mix flow rate of 5.6 L / h. The casting process was the same as in Example 1, and the process conditions are disclosed in Table 12. The 24 membranes were further surface-modified by prewetting them in water and then exposing them to an e-beam at a dose of 50 kGy. The membranes were rinsed with methanol followed by water and then dried. Membrane performance was tested after e-beam modification. The data are listed in Table 13. Membranes with much higher bubble points (33-46 psi) were produced by this process, and the throughput was at least 130% of that of the commercially available Millipore Express® SHRP. Most of the membrane rupture strains were greater than 40%.

[0146] Table 11: Mix formulation of Example 4 membrane with cloud point and viscosity data TIFF0007824215000011.tif184138Note: *Viscosity measured at 25°C with an S62 at 1.5 rpm; **Viscosity measured at 35°C with an S64 spindle at 10 rpm. Otherwise, measure at 25°C with an S62 spindle at 3 rpm.

[0147] Table 12: Casting conditions for Example 4 membranes (membranes 4A-4X) TIFF0007824215000012.tif146151

[0148] Table 13: Membrane performance of Example 4 membranes (membranes 4A to 4X) TIFF0007824215000013.tif148156

[0149] Both the Millipore Express® SHC and SHRP-scaled OptiScale®-25 mm devices were included as controls during all these throughput tests. As shown in Figure 7, increasing the membrane bubble point decreased membrane throughput, with all membranes prepared in this example exhibiting higher throughput, all above the dotted line. Over 150% of the throughput of the commercial Millipore Express® SHRP is achieved when the membrane bubble point is between 35 and 40 psi, as shown in Table 13.

[0150] Example 5 - Throughput comparison with commercial membranes The throughput of membranes taken from commercially available filters with bubble points ranging from 10 psi to 50 psi was tested as a comparison with the membranes of the present application.

[0151] Table 14 lists the membranes taken from different filters and used in the comparative throughput tests. Both the Millipore Express® SHC and SHRP scaled OptiScale®-25 devices were included as controls during the throughput tests. As shown in Figures 8A-8B, the throughput of all commercial membranes is much lower than that of the Millipore Express® filter, as shown by the dashed line.

[0152] Table 14: Bubble points of membranes collected from commercially available filters TIFF0007824215000014.tif90128

[0153] Example 6 - Pleatability for Hydrophilic Triple Zone Membranes Membranes 3A and 3C were pleated as prepared in Example 3 to confirm that no cracks would form during the pleating process of the membranes of the present application. TYPAR®, 178 μm thick, was used as both the upstream and downstream supports. The membranes were pleated at a pleat height of 0.465 inches at a rate of 50 pleats / min. After pleating, cross-sectional SEM images of the pleated membranes were taken and are shown in Figures 9A-9B. No obvious membrane cracks formed in the pleated membrane cross-section, indicating that these membranes are robust enough for the current pleating process.

[0154] Example 7 - Pleating properties for commercial membranes Two commercially available membranes developed for high-throughput applications, Millipore Express® PLUS 0.2 μm and Millipore Express® 0.5 μm, were tested for their pleatability.

[0155] The membranes were subjected to throughput, breaking strain and pleatability testing as described herein, and the results are shown in Table 15.

[0156] (Table 15) Membrane performance of commercially available membranes TIFF0007824215000015.tif50160

[0157] The Millipore Express® PLUS 0.2 μm and Millipore Express® 0.5 μm membranes are both single-ply membranes and were developed for high-throughput performance (see Table 15). However, their breaking strengths are much lower at 15% and 5%, respectively. The two membranes were pleated under the same conditions as described in Example 6. SEMs of the pleated membranes are shown in Figures 10A-10B. Clearly, severe cracks formed during the pleating process in both the Millipore Express® PLUS 0.2 μm and Millipore Express® 0.5 μm membranes.

[0158] While preferred embodiments have been described and illustrated in detail herein, it will be apparent to those skilled in the art that various modifications, additions, substitutions, etc. may be made therein without departing from the spirit of the present application and are therefore deemed to be within the scope of the present application as defined in the appended claims.

Claims

1. 1. A multi-zone, unsupported, microporous high-throughput filtration membrane having a bubble point (psi) of 15-50 and a strain to break of at least 20%, comprising: The membrane is a first microporous zone, which may be symmetric or asymmetric, comprising a blend of first polymers; a second microporous zone, which may be symmetric or asymmetric, comprising a blend of a second polymer; a third microporous zone that is asymmetric and comprises a third polymer blend; and the microporous zone of Including, the first, second, and third microporous zones are integral with one another, the third microporous zone being disposed between the first and second microporous zones; and The membrane has a throughput (L / m) of greater than -11.65x+1088.5 when measured using whey broth. ２ ), where x is the bubble point (psi), or has a throughput greater than −20.23x+1369.4 when measured using soy broth, where x is the bubble point (psi); Multi-zone, unsupported microporous high-throughput filtration membrane.

2. 10. The membrane of claim 1, wherein the first microporous zone is 5 to 140 μm thick, the second microporous zone is 10 to 140 μm thick, and the third microporous zone is 50 to 140 μm thick.

3. The membrane of claim 1 having a total thickness of 65 to 300 μm.

4. The membrane has a throughput (L / m) greater than -11.65x+1188.5 when measured using whey broth. ２ ), where x is the bubble point (psi), or a throughput (L / m) greater than -20.23x + 1469.4 as measured using soy broth. ２ 2. The membrane of claim 1, wherein x is the bubble point (psi).

5. The membrane of claim 1 having a strain at break of at least 25% or at least 30%.

6. 10. The membrane of claim 1, wherein the first, second, and third microporous zones comprise one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymers, methacrylic polymers, and acrylic or methacrylic copolymers.

7. The membrane of claim 1 , wherein the first, second, and / or third microporous zones are hydrophilic.

8. 8. The membrane of claim 7, wherein the first, second, and / or third microporous zones comprise a hydrophilic polymer independently selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl pyridine, polyethylene imine, and polyoxazoline.

9. 10. The membrane of claim 1, wherein the first, second, and / or third microporous zones independently comprise polyethersulfone and poly(2-ethyl-2-oxazoline).

10. 10. The membrane of claim 1, which can be pleated without a loss of membrane retention performance compared to an unpleated membrane.

11. The membrane of claim 1 which is pleated.

12. a hydrophilic coating on the membrane The membrane of claim 1 further comprising:

13. a first microporous zone, which may be symmetric or asymmetric; a second microporous zone, which may be symmetric or asymmetric; a third microporous zone that is asymmetric; and 1. A multi-zone, unsupported, microporous high-throughput filtration membrane comprising a membrane having: the first, second, and third microporous zones are integral with one another, the third microporous zone being disposed between the first and second microporous zones; and The first, second, and / or third microporous zones are: A blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and acrylic or methacrylic copolymer, and a second polymer selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. and The membrane has a breaking strain of at least 20% and a throughput (L / m) greater than -11.65x+1088.5 when measured using whey broth. ２ ), where x is the bubble point (psi), or has a throughput greater than −20.23x+1369.4 when measured using soy broth, where x is the bubble point (psi); Multi-zone, unsupported microporous high-throughput filtration membrane.

14. Housing and a pleated membrane disposed within the housing; and A filtration cartridge comprising: The membrane is a first microporous zone, which may be symmetric or asymmetric; a second microporous zone, which may be symmetric or asymmetric; a third microporous zone that is asymmetric; and Including, the first, second, and third microporous zones are integral with one another, with the third microporous zone being disposed between the first and second microporous zones; The first, second, and / or third microporous zones are: A blend of a first polymer selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymer, methacrylic polymer, and acrylic or methacrylic copolymer, and a second polymer selected from one or more hydrophilic polymers from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyethylene glycol, polyvinylpyridine, polyethyleneimine, and polyoxazoline. Including, The membrane has a breaking strain of at least 20% and a throughput (L / m) greater than -11.65x+1088.5 when measured using whey broth. ２ ), where x is the bubble point (psi), or has a throughput greater than −20.23x+1369.4 when measured using soy broth, where x is the bubble point (psi), and The housing has a thickness of 4.3 m per meter of housing height. ２ including an effective membrane area of ​​over Filtration cartridge.

15. The hydrophilic polymer is crosslinked, 14. The filtration cartridge according to claim 8 or 13.

16. Housing and A membrane according to any one of claims 1 to 12 disposed within the housing; a filtration cartridge comprising:

17. 14. The membrane of claim 13, wherein the first polymer is PES and the second polymer is poly(2-ethyl-2-oxazoline).

18. 1. A method for forming a multi-zone, microporous, high-throughput filtration membrane having a breaking strain of at least 20%, comprising: The method comprises: providing a solution of a polymer and a solvent for the polymer; casting the solution onto a support as three separate zones simultaneously or sequentially to form a multi-zone liquid sheet; causing a phase separation of the solution into three separate zones; and Separating the multi-zone, microporous high-throughput filtration membrane from the support Including, The membrane is a first microporous zone, which may be symmetric or asymmetric, comprising a blend of first polymers; a second microporous zone, which may be symmetric or asymmetric, comprising a blend of a second polymer; a third microporous zone that is asymmetric, the third microporous zone comprising a blend of a third polymer; Including, the first, second, and third microporous zones are integral with one another, the third microporous zone being disposed between the first and second microporous zones; and The membrane has a throughput (L / m) of greater than -11.65x+1088.5 when measured using whey broth. ２ ), where x is the bubble point (psi), or has a throughput greater than −20.23x+1369.4 when measured using soy broth, where x is the bubble point (psi); method.

19. 19. The method of claim 18, wherein the first microporous zone is 5 to 140 μm thick, the second microporous zone is 10 to 140 μm thick, and the third microporous zone is 50 to 140 μm thick.

20. The method of claim 18, wherein the membrane has a total thickness of 65 to 300 μm.

21. The membrane has a throughput (L / m) greater than -11.65x+1188.5 when measured using whey broth. ２ ), where x is the bubble point (psi) or a throughput (L / m) greater than -20.23x + 1469.4 as measured using soy broth. ２ 20. The method of claim 18, wherein x is the bubble point in psi.

22. The method of claim 18 , wherein the membrane has a breaking strain of at least 25% or at least 30%.

23. 20. The method of claim 18, wherein the first, second, and third microporous zones comprise one or more polymers independently selected from the group consisting of PVDF, polyamide, polyimide, polyethersulfone, polysulfone, polyarylsulfone, PVC, PET, polycarbonate, cellulose, regenerated cellulose, cellulose ester, polystyrene, polyetherimide, acrylic polymers, methacrylic polymers, and acrylic or methacrylic copolymers.

24. 20. The method of claim 18, wherein the first, second, and / or third microporous zones are hydrophilic.

25. 20. The method of claim 18, wherein the first, second, and / or third microporous zones comprise a hydrophilic polymer independently selected from the group consisting of polyacrylic acid, polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl pyridine, polyethylene imine, and polyoxazoline.

26. 19. The method of claim 18, wherein the first, second, and / or third microporous zones independently comprise polyethersulfone and poly(2-ethyl-2-oxazoline).

27. 20. The method of claim 18, wherein the membrane is pleated.

28. The hydrophilic polymer is crosslinked, 26. The method of claim 25.

29. 17. The filtration cartridge of claim 16, wherein the hydrophilic polymer is crosslinked.

Images