DETAILED ACTION
This action is in response to the RCE with amendments and remarks filed 12/12/2025 in which claims 1 and 11 haves been amended, claims 1-2, 5-6, 9 and 11-12 are pending, claims 11-12 are withdrawn and thus claims 1-2, 5-6 and 9 are ready for examination.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 12/12/2025 has been entered.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-2, 5-6 and 9 are rejected under 35 U.S.C. 103 as being unpatentable over US20120273421A1 (hereinafter “Perry”, filed 01/13/2010) in view of US 5,472,607 A (hereinafter “Mailvaganam’), US 4,127,625, issued November 28, 1978 (hereinafter “Arisaka”), Ba et al., Chemical modification of P84 copolyimide membranes by polyethylene- imine for nanofiltration, 327 J. Membrane Sci., 49, 49-58 (2009) (“Ba”), US 6,156,186 (hereinafter “Mueller”), as evidenced by Kafil & Yadollah Omidi, Cytotoxic Impacts of Linear and Branched Polyethyleneimine Nanostructures in A431 Cells, 1 BIOIMPACTS 28, 25 (2011). (hereinafter “Kafil”).
Regarding Claim 1 Perry discloses a method of forming a membrane (which may be a hollow fiber [0135]-[0136], and may be a nanofiltration membrane [0159]), the method comprising
forming a base polymer substrate 100, which may be aromatic poly(amide-imide) (PAI) [0119], and which may be a hollow fiber [0135]-[0136], where hollow fibers inherently have a lumen with an inner diameter (see MPEP 2112.01 with regard to inherency); and
contacting the base polymer substrate 100 (i.e. which may be a PAI hollow fiber substrate, as above) with an aqueous solution consisting of polyethyleneimine (PEI) at a temperature of 50-100°C [0138] to have the PEI covalently bonded to PAI in the PAI hollow fiber substrate so as to form a PEI-cross-linked PAI skin layer 102 on and part of an outer surface layer of the PAI hollow fiber substrate away from the lumen [0112]-[0114], [0135]-[0141],
wherein the PEI-cross-linked PAI skin layer will inherently be positively charged at a pH of less than 10.4 (see MPEP 2112.01 with regard to inherency),
wherein the aqueous solution of PEI has a concentration of PEI of 2-10 wt%, [0049],
wherein the PEI-cross-linked PAI skin layer has a nominal pore size in a range of about 0.5 nm to about 2 nm [0112]-[0116], [0302], and
wherein the PEI in the PEI-cross-linked PAI skin layer includes branched PEI [0393].
Since the range of contacting temperature disclosed overlaps the range claimed, the range recited in the claim is considered prima facie obvious. Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art to have selected the portion of the disclosed range that corresponds to the claimed range. See MPEP 2144.05(I).
Perry does not disclose (1) the lumen has an inner diameter that is greater than 1 mm; (2) sealing both ends of the PAI hollow fiber substrate, (3) wherein the aqueous solution of PEI has a concentration of PEI of 1 wt%, (4) wherein the PEI-cross-linked PAI skin layer has a nominal pore size in a range of about 0.5 nm to about 2 nm, or (5) wherein the PEI in the PEI-cross-linked PAI skin layer includes a unit represented by the claimed formula.
However, with regard to (1) the lumen inner diameter, Mailvaganam teaches a hollow fiber membrane that is suitable for nanofiltration and which uses an inner diameter within the range of about 0.3 mm to about 2.5 mm; (C11/L54–57).
Therefore, before the effective filing date, it would have been prima facie obvious to one of ordinary skill in the art to modify the method of Perry to select values of the hollow fiber lumen inner diameter in the range of about 0.3 mm to about 2.5 mm as disclosed by Mailvaganam since such values were suitable for providing filtration for a nanofilter.
Since the range disclosed overlaps the range claimed, the range recited in the claim is considered prima facie obvious. Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art to have selected the portion of the disclosed range that corresponds to the claimed range. See MPEP 2144.05(I).
With regard to (2) sealing both ends of the hollow fiber substrate, Arisaka discloses that coating the exterior surface of a hollow fiber substrate can be carried out by sealing both ends of the hollow fiber substrate, and subsequently either dipping the hollow fiber substrate in a polymer solution or simply coating the hollow fiber substrate with the polymer solution, (paragraph bridging cols. 5–6.) Arisaka further suggests that the purpose of sealing the hollow fiber substrate is to prevent the polymer solution from entering the interior of the hollow fiber substrate (C6/L8–11).
Previously it has been held that “[t]he combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results.” KSR, 550 U.S. at 415–16.
Therefore, before the effective filing date, it would have been prima facie obvious to one of ordinary skill in the art to modify the method of Perry such that both ends of the PAI hollow fiber substrate of the instant combination are sealed, prior to contacting said substrate with the aqueous solution of PEI as disclosed by Arisaka in order to yield the predictable results of: (1) forming a BPEI coating on the exterior surface of said substrate; and (2) preventing the aqueous solution of BPEI from entering the interior of the substrate.
With regard to (3) concentration of PEI, Ba discloses a similar method of forming a membrane by chemically modifying a base membrane (polyimide) to have a positively charged skin layer by covalently bonding branched PEI to the membrane substrate so as to form a PEI-crosslinked skin layer on and part of an outer surface of the membrane (Abstract, Sec. 3.4.), via immersing (i.e. contacting) the polyimide membranes in an aqueous solution of PEI at concentrations of 0.2%, 1%, or 5% wt/vol in water; (Secs. 2.3., 3.1.).
Therefore, before the effective filing date, it would have been prima facie obvious to one of ordinary skill in the art to modify the method of Perry by using 0.2-5% wt/vol PEI in water for the contacting aqueous solution as disclosed by Ba because this involves the simple substitution of known PEI coating concentrations used for forming a crosslinked PEI coating on a base membrane to obtain the predictable result of forming a successful membrane.
Given that water has a density of 1 g/cm3, these concentrations translate to 0.2%, 1%, or 5% wt%, respectively, and notably a value for water density of 0.983 as suggested by Applicants’ still results in a range which overlaps 1 wt%. Since the range disclosed overlaps the range claimed, the range recited in the claim is considered prima facie obvious. Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art to have selected the portion of the disclosed range that corresponds to the claimed range. See MPEP 2144.05(I).
With regard to (4) the PEI-cross-linked PAI skin layer pore size, Perry discloses in one embodiment that the membrane with base membrane 100 and the skin layer 102 is preferably an ultrafiltration membrane, having pore sizes from about 0.1 micron to about 5 nanometers [0112]-[0116], and in another embodiment that the membrane may be a nanofiltration membrane comprising an ultrafiltration membrane, as above, having an additional nanofiltration layer 108 [0159], [0172], wherein the nanofiltration layer may be PEI crosslinked with additional crosslinker [0053]-[0057], [0070], and wherein nanofiltration membranes “possess the ability to fractionate small compounds (i.e. those with molecular weights less than 1000)” [0303], but does not disclose achieving nanofiltration with the PEI-cross-linked PAI skin layer itself, and thus it is obvious that the PEI-cross-linked PAI skin layer has a nominal pore size in a range of about 0.1 micron to about 5 nanometers, slightly larger than the range on 0.5 to 2 nm as claimed. However Ba discloses a similar method of forming a membrane by chemically modifying a base membrane (polyimide) to have a positively charged skin layer by covalently bonding branched PEI to the membrane substrate so as to form a PEI-crosslinked skin layer on and part of an outer surface of the membrane (Abstract, Sec. 3.4.), and wherein the membrane is for nanofiltration, where base unmodified membranes having 10 nm pores are reacted with PEI to reduce the pore size from a range including the original 10 nm down to so small no pores were observed, by controlling PEI contacting duration (Sec. 3.3., Fig. 4), i.e. directly without an third nanofiltration layer.
Therefore, before the effective filing date, it would have been prima facie obvious to one of ordinary skill in the art to modify the method of Perry to form the skin layer of the membrane with pore sizes in the nanofiltration range directly, i.e. by controlling the base membrane pore size and PEI contacting duration, as disclosed by Ba, in order to yield the predictable result of providing a composite PEI skinned nanofiltration membrane in one coating step instead of two.
Pore sizes in the nanofiltration range are defined by Perry to be those which allow the membrane “the ability to fractionate small compounds (i.e. those with molecular weights less than 1000)” [0303], and notes specific use of the membrane for removing metals from liquid process steams (Abstract, [0053]), citing Mueller as a similar process for separating and in some cases recovering multivalent ions from process streams in leaching processes [0321], where Mueller discloses “[p]referred nanofiltration membranes have a pore size ranging from about 5 Å (or 0.0005 microns) to about 100 Å (or 0.01 microns)”; C11/44-47.
Therefore, before the effective filing date, it would have been prima facie obvious to one of ordinary skill in the art to modify the method of Perry in view of Ba to form the skin layer of the membrane to have a pore size ranging from about 5 Å (or 0.0005 microns) to about 100 Å (or 0.01 microns) as disclosed by Mueller, because these are known effective pore sizes for a nanofiltration membrane used to separate/recover metals for a process stream and thus this involves the simple substitution of known pore sizes used for forming a nanofiltration membrane used to separate/recover metals for a process stream to obtain the predictable result of forming a successful membrane and metals filtration process.
Since the range disclosed overlaps the range claimed, the range recited in the claim is considered prima facie obvious. Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art to have selected the portion of the disclosed range that corresponds to the claimed range. See MPEP 2144.05(I).
With regard to (5) PEI molecular structure, Perry discloses using “branched polyethylene imine” [0393], but does not disclose the structure of the branched PEI, however Kafil discloses it is known that the chemical structure for branched PEI is as follows:
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Therefore, before the effective filing date, it would have been prima facie obvious to one of ordinary skill in the art to modify the method of Perry by using branched PEI having the structure as disclosed by Kafil because this is a known molecular structure for branched PEI. Thus in the combined invention the PEI in the PEI-cross-linked PAI skin layer includes a unit represented by the formula as claimed.
Regarding Claim 2 Perry in view of Mailvaganam, Arisaka, Ba, Mueller and Kafil discloses the method of claim 1, and further, as detailed supra, the method of the instant combination includes immersing the PAI hollow fiber substrate in an aqueous PEI solution (Perry [0138], Arisaka paragraph bridging cols. 5–6).
Regarding Claims 5-6 Perry in view of Mailvaganam, Arisaka, Ba, Mueller and Kafil discloses the method of claim 1, wherein the contacting comprises contacting the PAI hollow fiber substrate with the aqueous PEI solution for a period of 1 to 72 hours; Perry [0138].
Since the range disclosed overlaps the range claimed, the range recited in the claim is considered prima facie obvious. Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art to have selected the portion of the disclosed range that corresponds to the claimed range. See MPEP 2144.05(I).
Regarding Claim 9 Perry in view of Mailvaganam, Arisaka, Ba, Mueller and Kafil discloses the method of claim 1, wherein Perry teaches that the PAI hollow fiber substrate comprises an asymmetric microporous hollow fiber, which may be made of PAI material; (Perry [0119], [0154], [0178]).
Response to Arguments
Applicant's arguments filed 12/12/2025 have been fully considered and they are persuasive with regard to the previous combination of references as they would apply to the amended claims; the Examiner agrees that Sun teaches away from a positively charged PEI coating as argued by Applicants, and therefore the previous rejections citing Sun are withdrawn, but they are now moot because they are directed in their entirety to grounds of rejection which are no longer cited in the current action and the new limitations of the amended claims which had not been previously addressed. See the updated rejection above citing a new combination of references to address the amended claims.
Conclusion
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/ERIC J MCCULLOUGH/ Examiner, Art Unit 1773
/BENJAMIN L LEBRON/ Supervisory Patent Examiner, Art Unit 1773