Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 May 18, 2026, has been entered.
Priority
Acknowledgment is made of applicant’s claim for foreign priority (KR10-2019-0076310, filed on 26 June 2019) under 35 U.S.C. 119 (a)-(d). Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Claim Objections
Claim 2 objected to because of the following informalities:
The phrase “R″ is defined in Chemical Formulae 1 and 2” should be corrected to read “R″ is as defined in Chemical Formulae 1 and 2” for grammatical consistency.
Appropriate correction is required.
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 (i.e., changing from AIA to pre-AIA ) 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 text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
Determining the scope and contents of the prior art.
Ascertaining the differences between the prior art and the claims at issue.
Resolving the level of ordinary skill in the pertinent art.
Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-2, 19-20 are rejected under 35 U.S.C. 103 as being unpatentable over YOON et al. (High flux nanofiltration membranes based on interfacially polymerized polyamide barrier layer on polyacrylonitrile nanofibrous scaffolds, 2008, hereinafter YOON) in view of ANG et al. (Correlating PSf Support Physicochemical Properties with the Formation of Piperazine-Based Polyamide and Evaluating the Resultant Nanofiltration Membrane Performance, 2017, hereinafter ANG).
Regarding Claims 1 and 2, YOON discloses a high flux thin film nanofibrous composite membrane for nanofiltration applications comprising an electrospun PAN nanofibrous scaffold support and a top polyamide barrier layer produced by interfacial polymerization of polyamides containing different ratios of piperazine and bipiperidine (Abstract, pg. 484).
In Fabricate polyamide barrier layer by interfacial polymerization, the thin film composite membranes were prepared on the PAN nanofibrous scaffold support and the PAN400 UF membrane support. Piperazine (i.e., Chemical Formula 2) and bipiperidine (i.e., Chemical Formula 1) dihydrochloride were dissolved in water, the total amine concentration ranged from 0.125% to 1% (w/v), and bipiperidine dihydrochloride ranged from 0% to 60% (w/w) with respect to the amount of piperazine. The support layers were wetted with the piperazine, bipiperidine, and triethylamine solution, NaOH was added to release free amine, and the trimesoyl chloride solution, 0.1% (w/v) in hexane, was introduced onto the amine impregnated support layer to form the polyamide barrier layer (§ 2.3, pgs. 486–487). In MgSO₄ salt filtration evaluation in the cross-flow mode, all filtration tests were conducted at 30–33°C (§ 2.5, pg. 487).
FIG. 2 schematically illustrates the interfacial polymerization procedure using unsubstituted piperazine and 4,4′-bipiperidine, where the ring nitrogen positions correspond to “–NR″–” and the remaining ring positions correspond to “–CRR′–,” with R, R′, and R″ being hydrogen for the unsubstituted structures depicted. As for Claim 2, bipiperidine has —NR″— at R3 and R8, and piperazine has —NR″— at R12 and R15; the remaining labeled positions are CRR′ with R, R′, and R″ as hydrogen.
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FIG. 2 of YOON
In Interfacial polymerizations using piperazine and bipiperidine with trimesoyl chloride on PAN UF membrane and PAN nanofibrous scaffold supports, the experiments were carried out in cross flow mode using MgSO₄ at 2000 ppm at 70 psi, and the pressure dependencies were investigated over a pressure range of 70 to 190 psi. The piperazine concentration was systematically changed from 0.125% to 1% while the other reaction parameters were fixed. As the piperazine concentration increased, the rejection rate of the TFNC membrane increased from 85.7% to 99.7%, while the permeate flux decreased. FIG. 4 further shows that when the piperazine concentration exceeded 0.5%, the barrier layer on the PAN UF support became thicker, resulting in a significant decrease in permeate flux (§ 3.2, pgs. 488-490). The disclosed rejection rate of 99.7% falls within the claimed “the membrane has a salt rejection of 99.7% or more.”
In Comonomer (bipiperidine) effect on the permeation performance of interfacially polymerized polyamide TFNC membranes, the total amine concentration was fixed at 1% (w/v), and the amount of bipiperidine was added up to 60% (w/w) with respect to the total amine concentration. Increasing the amount of bipiperidine increased the permeate flux from 80 to about 160 L/m²·h, while the rejection rate decreased from 99.8% to 89.9%. In the high permeate flux range above 100 L/m²·h, the bipiperidine/piperazine ratio could be fine-tuned to optimize the permeate flux and rejection rate of the TFNC membranes (§ 3.3, pgs. 490-491). The disclosed permeate flux of 80 to about 160 L/m²·h corresponds to about 47.1 to 94.2 gallons/ft²/day, which falls within the claimed “a permeate flux of 21 gallons/ft²/day or more.”
In Performance comparison between TFNC membranes and commercial NF membranes: NF90 and NF270, NF90 and NF270 are nanofiltration membranes comprising an interfacially polymerized piperazamide coating on a polysulfone microporous support. NF90 exhibited a MgSO₄ rejection rate of 99.9% (§ 3.4, pg. 491).
However, YOON does not explicitly disclose “a porous layer comprising a cast polysulfone layer,” the salt rejection and permeate flux being measured under the claimed combination of “2,000 ppm of an aqueous MgSO₄ solution, a pressure of 130 psi, and a temperature of 25°C,” or an FT-IR absorbance ratio satisfying “0.28≤Aa/Ab≤0.50,” wherein Aa is an absorbance value at a wave number of 1640 cm⁻¹ and Ab is an absorbance value at a wave number of 1587 cm⁻¹.
ANG discloses thin-film composite nanofiltration membranes comprising polysulfone supports and piperazine-based polyamide layers formed by interfacial polymerization, with the support properties influencing membrane performance (Abstract, pg. 1).
In Fabrication of Thin-Film Composite Membranes, a continuous casting machine fed with nonwoven polyester was used to prepare a PSf support by a wet-phase inversion method. A casting solution containing 16 wt% PSf/NMP was poured into the continuous casting machine using a casting knife gap of 200 μm. Before interfacial polymerization, the PSf support was impregnated with an aqueous solution containing piperazine and 4-aminobenzoic acid, and 0.2 wt% TMC/n-hexane was applied to the PSf surface to form a thin layer through interfacial polymerization (§ 2.2, pgs. 3–4).
In Membrane Characterization, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to verify the formation of a thin polyamide layer on PSf, along with the measurement of the surface porosity, surface pore size, and membrane thickness (§ 2.3, pg. 4).
In Chemical Structure of Polysulfone Supports and Thin-Film Composite Membranes, ATR-FTIR spectra of the PSf supports showed aromatic C=C absorption peaks at 1587, 1504, and 1410 cm⁻¹. Formation of the polyamide layer on the PSf supports was confirmed by new absorption peaks at 1620 and 3400 cm⁻¹, with the 1620 cm⁻¹ peak corresponding to amide I (–C=O). The polyamide absorption peaks were not appreciably affected by variations in PEG molecular weight (§ 3.1, pgs. 5–6).
In Properties of Polysulfone Supports Modified Using Polyethylene Glycol of Different Molecular Weights, the PSf supports prepared by phase inversion were asymmetric, comprising a dense skin layer over a porous sublayer containing macrovoids. Increasing the PEG molecular weight decreased the surface porosity and surface pore size and increased the skin layer thickness, while the bulk porosity remained within 82.0% to 86.2% (§ 3.2.1, pgs. 6–7).
In Separation Performance Test, the TFC membrane performance was evaluated using 1000 ppm aqueous Na₂SO₄ at 0.60 MPa and 25°C. The membranes exhibited salt rejection of approximately 91% to 93%, while changes in the PSf support properties affected water flux. The TFC-PEG20k membrane provided the highest water flux, attributed to the low surface porosity, small surface pore size, and suitable hydrophilicity of the PSf support, which favored formation of a defect-free polyamide layer (§ 3.2.3, pg. 11).
The cast PSf supports disclosed by ANG exhibiting low surface porosity, small surface pore size, and suitable hydrophilicity, favored formation of a polyamide layer with high water flux (Conclusion, pg. 13). In view of YOON forming a BP/PIP polyamide barrier layer on a porous support for nanofiltration, a person skilled in the art would incorporate the cast PSf support into the nanofiltration membrane as the porous support for the BP/PIP polyamide barrier layer to predictably promote high water flux.
Regarding the claimed combined test conditions of “2,000 ppm of an aqueous MgSO₄ solution, a pressure of 130 psi, and a temperature of 25°C,” YOON evaluates the BP/PIP polyamide membrane using 2,000 ppm MgSO₄ over a pressure range of 70 to 190 psi at 30–33°C and reports a salt rejection of 99.7%, while ANG evaluates nanofiltration membrane performance at 25°C. Neither reference expressly evaluates membrane performance under the claimed combined test conditions. However, these testing conditions define how membrane performance is measured and do not impart an additional chemical composition or structural feature to the membrane.
Accordingly, modified YOON produces a membrane having substantially identical chemical composition and membrane structure as the claimed separation membrane, which would inherently exhibit substantially the same salt rejection and permeate flux when measured under the claimed combined test conditions (In re Best, 562 F.2d 1252, 1255; 1977).
Regarding the limitations “Aa means an absorbance value at a wave number of 1640 cm⁻¹ during an FT-IR analysis” and “Ab means an absorbance value at a wave number of 1587 cm⁻¹ during an FT-IR analysis,” ANG discloses the use of ATR-FTIR to characterize a polyamide/PSf nanofiltration membrane. The ATR-FTIR spectra identify a PSf absorption at 1587 cm⁻¹, identical to the claimed wavenumber for Ab, and a polyamide amide I absorption at 1620 cm⁻¹, close to the claimed wavenumber of 1640 cm⁻¹ for Aa. Accordingly, ATR-FTIR was a known characterization technique for obtaining absorbance values corresponding to the PSf porous support and polyamide active layer at the same or closely corresponding wavenumbers.
Regarding the limitation “0.28≤Aa/Ab≤0.50,” the Aa/Ab ratio characterizes the relative thickness of the polyamide active layer to the PSf porous layer. As discussed above, modified YOON results in a membrane having substantially the same chemical composition and membrane structure as the claimed separation membrane, including a BP/PIP polyamide active layer formed by interfacial polymerization on a cast PSf porous support. Accordingly, there is a sound basis for concluding that the substantially identical membrane would inherently possess substantially the same structural properties (In re Best, 562 F.2d 1252, 1255; 1977).
Further, YOON recognizes that polyamide barrier-layer thickness affects membrane performance, including permeate flux, and that changes in the interfacial polymerization conditions affect both salt rejection and permeate flux. Thus, the relative thickness of the polyamide active layer to the porous layer is a result-effective variable that a person skilled in the art would have routinely optimized to obtain the desired balance between salt rejection and permeate flux. The claimed Aa/Ab range represents the FT-IR characterization of the resulting relative layer thickness. Accordingly, optimization of the relative layer thickness to obtain an Aa/Ab value within the claimed range would have involved routine optimization of a result-effective variable (In re Aller, 220 F.2d 454, 456–57; 1955).
Therefore, it would have been obvious to a person having ordinary skill in the art, prior to the effective filing date of the claimed invention, to incorporate the cast PSf porous support, as disclosed by ANG, into the porous layer in the separation membrane by YOON.
Regarding Claim 19, modified YOON makes obvious the separation membrane of Claim 1. YOON discloses a thin-film composite separation membrane for nanofiltration applications (Abstract, pg. 484).
Regarding Claim 20, modified YOON makes obvious the separation membrane of Claim 1. YOON discloses the use of piperazine and 4,4′-bipiperidine as amine monomers in forming the polyamide barrier layer by interfacial polymerization (§ 2.3, pgs. 486–487; FIG. 2).
Claims 17 and 18 rejected under 35 U.S.C. 103 as being unpatentable over YOON in view of ANG, as applied to claim 1 above, and further in view of ZHANG et al. (CN108079806A, hereinafter ZHANG).
Regarding Claims 17 and 18, modified YOON makes obvious the separation membrane of Claim 1. However, modified YOON does not explicitly disclose “polyvinyl alcohol incorporated into the active layer at interfacial polymerization for mechanical strength of the active layer” or “a protective layer comprising polyvinyl alcohol, polyethylene glycol, or glycerol on the active layer of the separation membrane.”
ZHANG discloses a polyamide semipermeable membrane, its preparation method, and its application in the field of separation (¶[0002]). The chemical composition of the semipermeable membrane contains macromolecules, with polyvinyl alcohol (PVA) identified as a preferred macromolecule. The membrane is prepared by contacting and reacting, on a porous support, a polar solvent solution containing a compound having at least two amine groups and the macromolecule with a nonpolar solvent solution containing a compound having at least two acyl halide groups. Piperazine is identified as a preferred amine reaction monomer, water is preferably used as the polar solvent, and the amine compound can be present at 0.1–5.0% (w/v) in the polar solvent solution (¶[0023]–¶[0025]).
In Example 12, during interfacial polymerization, a polar solution comprising 0.2% (w/v) piperazine and 0.2% (w/v) polyvinyl alcohol was impregnated on a polysulfone porous support, followed by contact with a nonpolar solution containing 0.2% (w/v) 1,3,5-benzenetricarboxylic acid chloride. After the reaction and heat treatment, a polyamide semipermeable membrane was obtained (¶[0113]). In Example 3, as a post-treatment, the polyamide layer was coated with a solution containing 0.5% (w/v) polyvinyl alcohol, 0.2% (w/v) glutaraldehyde, and 0.02% (w/v) hydrochloric acid, resulting in a polyamide semipermeable membrane on a polysulfone porous support (¶[0083]).
The application of PVA during polyamide membrane formation disclosed by ZHANG provides a chemically stable, low-cost, and highly practical macromolecule, while the post-treatment improves water permeation flux, salt rejection rate, and antifouling performance (¶[0023], ¶[0035]). In view of modified YOON’s BP/PIP polyamide active layer formed by interfacial polymerization on a porous support, a person skilled in the art would apply PVA during formation of the polyamide active layer and as a post-treatment coating on the active layer to predictably provide a practical PVA-containing polyamide membrane with improved separation and antifouling performance.
Regarding the limitation “for mechanical strength of the active layer,” this language states a result or purpose of the recited PVA incorporation and does not require a particular mechanical-strength value or additional structural feature. ZHANG establishes in Example 12 that PVA-containing polyamide active layers formed by interfacial polymerization were known in the art. Accordingly, the recited purpose of providing mechanical strength does not further distinguish the claimed membrane from the substantially same chemical composition and structure (In re Schreiber, 128 F.3d 1473, 1477; 1997).
Therefore, it would have been obvious to a person having ordinary skill in the art, prior to the effective filing date of the claimed invention, to incorporate PVA into the polyamide active layer during formation and onto the active layer as a post-treatment coating, as disclosed by ZHANG, in the separation membrane by modified YOON.
Response to Arguments
Applicant’s arguments, see Remarks, filed May 18, 2026, with respect to the rejection under 35 U.S.C. § 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, new grounds of rejection are made under 35 U.S.C. § 103 in view of YOON, ANG, and ZHANG.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to TAK L. CHIU whose telephone number is (703)756-1059. The examiner can normally be reached M-F: 9:00am - 6:00pm (CST).
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/TAK L. CHIU/Examiner, Art Unit 1771
/KRISHNAN S MENON/Primary Examiner, Art Unit 1771
