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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 January 15, 2026 has been entered.
The amendment filed December 19, 2025 has been entered and considered as requested by the RCE submission of January 15, 2026. With the entry of the amendment, claims 4, 9-10 and 16 are canceled, claims 13-15 are withdrawn and claims 1-3, 5-8, 11-12 and 17-18 are pending for examination.
Election/Restrictions
Applicant’s election without traverse of Group I, claims 1-12, in the reply filed on March 18, 2024 is acknowledged.
Claims 13-15 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on March 18, 2024.
Claim Rejections - 35 USC § 112
The rejection of claims 1-3, 5-8, 11-12 and 17-18 under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention is withdrawn due to the amendment of December 19, 2025 clarifying the claim language.
The following is a quotation of 35 U.S.C. 112(d):
(d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
The following is a quotation of pre-AIA 35 U.S.C. 112, fourth paragraph:
Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA 35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
Claim 18 is rejected under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends.
Claim 18 has the maximum solubility of the PBI based compound in a “range of 10 to 20% by weight, based on 100% by weight of the dimethyl acetamide solvent”. However, parent claim 1 (by way of claim 17), requires the maximum solubility to be 8 to 12% by weight, based on 100% by weight of the dimethyl acetamide solvent. Since the range in claim 18 is broader than that in claim 1 (allowing over 12 to 20 % by weight not allowed by claim 1), claim 18 is not further limiting of claim 1.
Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements.
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 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 1-3, 5 and 17-18 are rejected under 35 U.S.C. 103 as being unpatentable over Li, et al “A low cost shutdown sandwich-like composite membrane with superior thermo-stability for lithium-ion battery” (hereinafter Li article) in view of KR 20220146891 (hereinafter ‘891), Gubler, et al “Composite Membranes Containing a Porous Separator and a Polybenzimidazole Thin Film for Vanadium Redox Flow Batteries” (hereinafter Gubler article), CN 111205465 (hereinafter ‘465) and Staiti, et al “Sulfonated polybenzimidazole membranes – preparation and physico-chemical characterization” (hereinafter Staiti article).
Claims 1, 17-18: Li article teaches a method for manufacturing a polybenzimidazole (PBI)-based separator (note abstract, section 2.2, combined separator and membrane can be considered a resulting separator, Scheme 1, and considered PBI based due to the PBI coating). The method comprises dissolving a PBI-based compound in a dimethyl acetamide solvent (N,N-dimethylacetamide, DMAC) to produce a PBI solution (section 2.2, and note section 1 indicating PBI as polybenzimidazole). A porous membrane (PE separator) was impregnated with the PBI solution (immersed in solution where PBI diffuses through the pores of the PE separator and precipitated on pore walls of the separator, and therefore is impregnated) (note section 2.2, Scheme 1 and section 3, page 4, column 1). The impregnated porous membrane is dried at a temperature of 70 degrees C (less than 80 degrees C) to obtain the PBI based separator (section 2.2). In Li article, the porous membrane is made of polyethylene (PE) (note section 2.2, and section 1 describing PE as polyethylene).
(A) As to the use of the manufactured separator for a secondary battery as claimed, Li article describes that a separator membrane is formed (abstract) and describes its use for lithium ion batteries (abstract).
‘891 further describes the use of a PBI based membrane for use in a redox flow battery (secondary battery), where the battery can be a redox battery using oxidation and reduction reactions of a vanadium redox couple and acid electrolyte (note pages 2, 3, translation), where the PBI based membrane (which has been manufactured, where the membrane can have additional porous polymer used) is provided and treated with sulfuric acid, and then used in the battery (since a battery is provided with this separator) (note page 3, translation).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Li article to further use the manufactured separator for a secondary battery including a redox battery as claimed as suggested by ‘891 with an expectation of providing a further desirable use for the separator, since Li article makes a PBI based separator for use in batteries, and ‘891 indicates how a further use of for a PBI based separator is for use in secondary batteries including a redox battery using oxidation and reduction reactions of a vanadium redox couple and acid electrolyte.
(B) Further as to the specific use of the PBI based compound of m-PBI,
Gubler article describes how mPBI (meta-polybenzimidazole) can be used as a PBI material for membrane separators for vanadium redox flow batteries (note abstract, first column of Experimental Section, Conclusions section).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Li article in view of ‘891 to use mPBI as the specific PBI compound to use as suggested by Gubler article with an expectation of predictably acceptable results, since Li article uses a PBI compound for the separator, ‘891 suggests the use of the PBI compound for forming a PBI based separator for use in vanadium redox batteries, and Gubler article indicates that an acceptable PBI based compound to use for separators for vanadium redox batteries would be mPBI, giving a suggested PBI compound for using in the process of Li article as well.
(C) Further as to providing that the dissolving occurs under a temperature in the range of 130-160 degrees C (claim 1) or 140-160 degrees C (claim 17), and the maximum solubility is 8-12 wt% (claim 1) or 10-12 wt% (claim 18), Li article notes dissolving the PBI compound in DMAC making a 4 wt% solution (note section 2.2). Gubler article further describes how when using mPBI for vanadium redox batteries the mPBI can be provided as a 10 wt% solution in DMAC (10 % by weight mPBI, from 25 g mPBI and 225 g DMAC), where the temperature of dissolving is described at 60 degrees C (note Experimental section, first and second columns).
‘465 further describes that mPBI can be provided in an approx. 10.7 wt% solution of DMAC (1 g of mPBI and 10 ml of DMAC, where the Examiner takes Official Notice that DMAC conventionally has a density of about 9.37 g/ml, giving 9.37 g of DMAC from 10 ml) by adding the mPBI to the solvent and heating at 110-140 degrees C to completely dissolve (note translation, page 4).
Staiti article describes how PBI compounds can be formed into membranes that are further treated (note sections 2.1 to 2.2). Staiti article indicates to solubilize (dissolve) in DMAC at 150 degrees C for a period of time to provide a solution with 12.5 wt% PBI for use in the membrane forming (note section 2.1).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Li article in view of ‘891 and Gubler article to dissolve the PBI compound in the DMAC solvent at a temperature of 140 degrees or 150 degrees C, for example (in the ranges of claims 1, 17), and in an amount within the range of 10-12 wt%, for example, as maximum solubility (in the ranges of claims 1, 18) as suggested by Gubler article, ‘465 and Staiti article with an expectation of predictably acceptable results, since Li article uses PBI compound dissolved in a solution of DMAC, where the use of m-PBI is suggested by Gubler article, and it is indicated from Gubler article that the temperature for dissolving such mPBI in DMAC can be 60 degrees C for a 10 wt% solution of mPBI, ‘465 describes complete dissolving of a similar amount of mPBI in DMAC can be at 110-140 degrees C, and Staiti article indicates how PBIs in general can be dissolved at a temperature of 150 degrees C, and one of ordinary skill in the art would optimize the amount of PBI compound used, from the options given, giving a value in the claimed range, with the adjustment of the amount allowing more or less PBI compound to be provided in a relative amount of solution for use, and as well would be suggested to use an amount within 10-12 wt% mPBI as an amount suggested specifically for mPBI for battery separators and to provide this as maximum solubility as providing the amount of material desired; and one would also optimize the temperature used from the possible values and ranges given, giving a temperature in the claimed range. Also note MPEP 2144.05(II)(A): “Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955) “.
Claim 2: in Li article, no backing (removable) substrate is used (note Scheme 1 and section 2.2).
Claim 3: in Li article, both opposing surfaces are impregnated, due to the immersion in the solution (Scheme 1, section 2.2, and note the impregnating from the immersion as discussed for claim 1 above).
Claim 5: in Li article the thickness of the porous membrane (PE separator) is 20 microns (note section 2.2, Table 2, and also section 3, page 4, column 1, where each PBI layer is 4 microns, and total membrane thickness 28 microns (Table 2, section 2.2), so leaving 20 microns for the membrane), in the claimed range, and the thickness of formed separator is 28 microns (section 2.2, in the claimed range).
Claims 6-8 are rejected under 35 U.S.C. 103 as being unpatentable over Li article in view of ‘891, Gubler article, ‘465 and Staiti article as applied to claims 1-3, 5 and 17-18 above, and further in view of Livingston et al (US 2013/0118983).
Claims 6-8: As to the use of a surfactant, and its amount and type,
Livingston further describes how membranes can be made (note 0001), where PBI based solutions can be used, where the PBI solutions are made with PBI polymer and solvent, such as N,N-dimethylacetamide (DMAc) and N, N-dimethylformamide, etc. (note 0040-0046, 0048, 0088). Livingston notes mPBI (note the formula shown) is a preferred PBI to use (note 0037). It is described that when providing solutions, additionally a surfactant can be present, which help influence the resulting pore structure, where the surfactant can be provided in an amount of up to 5 wt% of the solution and can be TRITON X-100 (oxylphenoxy-poly-ethoxyethanol) (note 0045, 0050).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Li article in view of ‘891, Gubler article, ‘465 and Staiti article to provide the solution also includes surfactant such as TRITON X-100 as suggested by Livingston to help control pore structure, as Li article provides how a PBI based separator can be provided by immersing a membrane material in PBI based solution giving a porous structure and notes pores for ion conductivity in the PBI layer (page 4, column 1), Gubler article suggests using mPBI, and Livingston indicates that when using PBI (which can include mPBI) solutions with amide based organic solvent, adding surfactant to the solution can also be used to help control resulting pore structure of the formed material. It would be understood that the provided surfactant would also dissolve in the solution as the same surfactant used by applicant (note TRITON X-100 also listed by applicant 00117 of the specification) and the same solvents used by applicant are used (note DMAc, with DMAc described by applicant, 00129 of the specification). For claim 7, Livingston would suggest using up to 5 wt% of the solution, overlapping the claimed range. It would have been obvious to optimize from within the taught range, giving a value in the claimed range. Note that In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). For claim 8, Livingston suggests TRITON X-100, where this is described as an organic material (so organic surfactant), and as well applicant identifies this also as a non-ionic surfactant (00117 of the specification).
Claims 11 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Li article in view of ‘891, Gubler article, ‘465, Staiti article and Livingston, as applied to claims 6-8 above, and further in view of Cabasso et al (US 2004/0028976).
Claims 11-12: As to use of a viscosity control solvent and its amount and material,
Livingston further notes that solvents which can be used for dissolving the PBI compound can be DMAc, etc. but also can be mixtures that also include alcohols (note 0048). Livingston also notes that viscosity adjusters (enhancers) can be used, describing amounts of up to 10 wt% in the solution, but does not specifically provide using solvents for this purpose (note 0050).
Cabasso describes providing PBI compounds and dissolving in solvents such as N, N-dimethylacetamide (DMAc), etc. (0040) where it is also described how solvents that can dissolve can be DMAc and also lower alcohols such as methanol, ethanol and isopropanol (note 0051). The PBI compound can be mPBI (note 0011 formula).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Li article in view of ‘891, Gubler article, ‘465, Staiti article and Livingston to dissolve the PBI compound using a mixture of DMAc (amide solvent) and also alcohols such as methanol, ethanol, and isopropanol as suggested by Livingston and Cabasso with an expectation of predictably acceptable results, as Li article provides how a PBI solution can be provided by dissolving a PBI based compound and solvent such as DMAC/DMAc, Gubler articles indicates using mPBI and also dissolving in DMAC, and Livingston indicates that for dissolving such compounds one can use DMAC/DMAc and also alcohols in a mixture and Cabasso indicates that when dissolving PBI compound (including mPBI), DMAc, and alcohols such as methanol, ethanol and isopropanol can be used. By using the additional ethanol, methanol or isopropanol, a viscosity control solvent as in claims 11 and 12 would be used. As to the amount of the viscosity control solvent, it would have been obvious to optimize the specific amount of each solvent used, giving an amount in the claimed range. Note MPEP 2144.05(II)(A): “Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955) “.
Claims 1-3 and 17-18 are rejected under 35 U.S.C. 103 as being unpatentable over Verzwyvelt (US 4217404) in view of KR 20220146891 (hereinafter ‘891), Gubler, et al “Composite Membranes Containing a Porous Separator and a Polybenzimidazole Thin Film for Vanadium Redox Flow Batteries” (hereinafter Gubler article), CN 111205465 (hereinafter ‘465) and Staiti, et al “Sulfonated polybenzimidazole membranes – preparation and physico-chemical characterization” (hereinafter Staiti article).
Claims 1, 17-18: Verzwyvelt teaches a method for manufacturing a polybenzimidazole (PBI)-based separator (note separator saturated/coated with PBI, so considered PBI based, note column 1, line 60 to column 2, line 20). The method comprises dissolving a PBI-based compound in an dimethyl acetamide solvent (such dimethylacetamide, DMA (or could also be called DMAC)) to produce a PBI solution (note column 2, lines 45-55, column 3, lines 15-30, for example). A porous membrane (note column 3, lines 20-35 and 50-60, column 3, line 65 to column 4, line 10) was impregnated with the PBI solution (immersed in solution, or vacuum backfilled, for example, where the solution will enter the pores/openings of membrane and coat/impregnate) (note column 3, line 15 to column 4, line 15, and note the described impregnation in claim 1). The impregnated porous membrane is dried at a temperature of not exceeding 100 degrees C (note column 2, lines 15-20), so giving a range of up to 100 degree C overlapping the claimed range. It would have been obvious to optimize from within the taught range, giving a value in the claimed range. Note that In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). While applicant has one example with a drying temperature higher than 80 degrees C giving shrinkage, this example uses a specific PBI amount, application type, solution, etc. and a showing is not made commensurate in scope with the entire claims, so no criticality has been shown. In Verzwyvelt, the porous membrane can be made of polypropylene or polyethylene (note column 1, lines 65-68, column 3, lines 15-65).
(A) As to the use of the manufactured separator for a secondary battery as claimed, Verzwyvelt describes that a separator is formed (abstract) and describes its use for alkaline storage batteries (column 1, lines 20-25), where what can be considered a membrane is formed (note column 3, line 65 to column 4, line 15 with an impregnated membrane).
‘891 further describes the use of a PBI based membrane for use in a redox flow battery (secondary battery), where the battery can be a redox battery using oxidation and reduction reactions of a vanadium redox couple and acid electrolyte (note pages 2, 3, translation), where the PBI based membrane (which has been manufactured, where the membrane can have additional porous polymer used) is provided and treated with sulfuric acid, and then used in the battery (since a battery is provided with this separator) (note page 3, translation).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Verzwyvelt to further use the manufactured separator for a secondary battery including a redox battery as claimed as suggested by ‘891 with an expectation of providing a further desirable use for the separator, since Verzwyvelt makes a PBI based separator for use in batteries, and ‘891 indicates how a further use of for a PBI based separator is for use in secondary batteries including a redox battery using oxidation and reduction reactions of a vanadium redox couple and acid electrolyte.
(B) As to the specific PBI compound used, Verzwyvelt describes using PBI (note Example 1).
Gubler article describes how mPBI (meta-polybenzimidazole) can be used as a PBI material for membrane separators for vanadium redox flow batteries (note abstract, first column of Experimental Section, Conclusions section).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Verzwyvelt in view of ‘891 to use mPBI as the specific PBI compound to use as suggested by Gubler article with an expectation of predictably acceptable results, since Verzwyvelt uses a PBI compound for the separator, ‘891 suggests the use of the PBI compound for forming a PBI based separator for use in vanadium redox batteries, and Gubler article indicates that an acceptable PBI based compound to use for separators for vanadium redox batteries would be mPBI, giving a suggested PBI compound for using in the process of Li article as well.
(C) As to further as to providing that the dissolving occurs under a temperature in the range of 130-160 degrees C (claim 1) or 140-160 degrees C (claim 17), and the maximum solubility is 8-12 wt% (claim 1) or 10-12 wt% (claim 18), Verzwyvelt describes that PBI can be used in a solution of 5% w/v PBI in DMAC, for example (note column 3, lines 45-50). Gubler article further describes how when using mPBI for vanadium redox batteries the mPBI can be provided as a 10 wt% solution in DMAC (10 % by weight mPBI, from 25 g mPBI and 225 g DMAC), where the temperature of dissolving is described at 60 degrees C (note Experimental section, first and second columns).
‘465 further describes that mPBI can be provided in an approx. 10.7 wt% solution of DMAC (1 g of mPBI and 10 ml of DMAC, where the Examiner takes Official Notice that DMAC conventionally has a density of about 9.37 g/ml, giving 9.37 g of DMAC from 10 ml) by adding the mPBI to the solvent and heating at 110-140 degrees C to completely dissolve (note translation, page 4).
Staiti article describes how PBI compounds can be formed into membranes that are further treated (note sections 2.1 to 2.2). Staiti article indicates to solubilize (dissolve) in DMAC at 150 degrees C for a period of time to provide a solution with 12.5 wt% PBI for use in the membrane forming (note section 2.1).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Verzwyvelt in view of ‘891 and Gubler article to dissolve the PBI compound in the DMAC solvent at a temperature of 140 degrees or 150 degrees C, for example (in the ranges of claims 1, 17), and in an amount within the range of 10-12 wt% as maximum solubility (in the ranges of claims 1, 18) as suggested by Gubler article, ‘465 and Staiti article with an expectation of predictably acceptable results, since Verzwyvelt uses PBI compound dissolved in a solution of DMAC, where the use of m-PBI is suggested by Gubler article, and it is indicated from Gubler article that the temperature for dissolving such mPBI in DMAC can be 60 degrees C for a 10 wt% solution of mPBI, ‘465 describes complete dissolving of a similar amount of mPBI in DMAC can be at 110-140 degrees C, and Staiti article indicates how PBIs in general can be dissolved at a temperature of 150 degrees C, and one of ordinary skill in the art would optimize the amount of PBI compound used, from the options given, giving a value in the claimed range, with the adjustment of the amount allowing more or less PBI compound to be provided in a relative amount of solution for use, and as well would be suggested to use an amount within 10-12 wt% mPBI as an amount suggested specifically for mPBI for battery separators and to provide this as maximum solubility as providing the amount of material desired; and one would also optimize the temperature used from the possible values and ranges given, giving a temperature in the claimed range. Also note MPEP 2144.05(II)(A): “Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955) “.
Claim 2: In Verzwyvelt, no backing (removable) substrate is needed to be used to form the separator (note the examples of column 3, line 15 to column 4, line 15).
Claim 3: In Verzwyvelt, both surfaces of the membrane can be impregnated (such as by immersing), for example (note column 3, lines 15-65, claim 1).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Verzwyvelt, in view of ‘891, Gubler article, ‘465 and Staiti article as applied to claims 1-3 and 17-18 above, and further in view of Li, et al “A low cost shutdown sandwich-like composite membrane with superior thermo-stability for lithium-ion battery” (hereinafter Li article).
Claim 5: As to the specific thickness of the porous membrane and the resulting PBI based separator,
Li article teaches a method for manufacturing a polybenzimidazole (PBI)-based separator (note abstract, section 2.2, combined separator and membrane can be considered a resulting separator, Scheme 1, and considered PBI based due to the PBI coating). The method comprises dissolving a PBI-based compound in an amide based organic solvent (N,N-dimethylacetamide, DMAC) to produce a PBI solution (section 2.2, and note section 1 indicating PBI as polybenzimidazole). A porous membrane (PE separator) was impregnated with the PBI solution (immersed in solution where PBI diffuses through the pores of the PE separator and precipitated on pore walls of the separator, and therefore is impregnated) (note section 2.2, Scheme 1 and section 3, page 4, column 1). The impregnated porous membrane is dried at a temperature of 70 degrees C (less than 80 degrees C) to obtain the PBI based separator (section 2.2). Furthermore, in Li article the thickness of the porous membrane (PE separator) is 20 microns (note section 2.2, Table 2, and also section 3, page 4, column 1, where each PBI layer is 4 microns, and total membrane thickness 28 microns (Table 2, section 2.2), so leaving 20 microns for the membrane), in the claimed range, and the thickness of formed separator is 28 microns (section 2.2, in the claimed range).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Verzwyvelt, in view of ‘891, Gubler article, ‘465 and Staiti article to provide the membrane thickness of 20 microns and the PBI based separator thickness of 28 microns as suggested by Li article as giving a predictably acceptable membrane and PBI based separator thickness to provide, since Verzwyvelt provides how a PBI based separator can be provided by immersing a membrane material in PBI based solution, and Li article indicate how in a similar process as described above, the membrane thickness can be 20 microns and the PBI based separator thickness 28 microns, both in the claimed range.
Claims 6-8 are rejected under 35 U.S.C. 103 as being unpatentable over Verzwyvelt, in view of ‘891, Gubler article, ‘465 and Staiti article as applied to claims 1-3 and 17-18 above, and further in view of Livingston et al (US 2013/0118983).
Claims 6-8: As to the use of a surfactant, and its amount and type,
Livingston further describes how membranes can be made (note 0001), where PBI based solutions can be used, where the PBI solutions are made with PBI polymer and solvent, such as N,N-dimethylacetamide (DMAc) and N, N-dimethylformamide, etc. (note 0040-0046, 0048, 0088). The PBI polymer can be preferably mPBI (note the formula in 0037). It is described that when providing solutions, additionally a surfactant can be present, which help influence the resulting pore structure, where the surfactant can be provided in an amount of up to 5 wt% of the solution and can be TRITON X-100 (oxylphenoxy-poly-ethoxyethanol) (note 0045, 0050).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Verzwyvelt, in view of ‘891, Gubler article, ‘465 and Staiti article to provide the solution also includes surfactant such as TRITON X-100 as suggested by Livingston to help control pore structure, as Verzwyvelt provides how a PBI based separator can be provided by immersing a membrane material in PBI based solution giving a porous structure and notes control of gas permeability (porous structure formation) based on coating conditions (note column 3, lines 1-15), Gubler article suggests using mPBI, and Livingston indicates that when using PBI solutions with amide based organic solvent (including where the PBI can be mPBI and the solvent DMAC), adding surfactant to the solution can also be used to help control resulting pore structure of the formed material. It would be understood that the provided surfactant would also dissolve in the solution as the same surfactant used by applicant (note TRITON X-100 also listed by applicant 00117 of the specification) and the same solvents used by applicant are used (note DMAc, with DMAc described by applicant, 00129 of the specification). For claim 7, Livingston would suggest using up to 5 wt% of the solution, overlapping the claimed range. It would have been obvious to optimize from within the taught range, giving a value in the claimed range. Note that In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). For claim 8, Livingston suggests TRITON X-100, where this is described as an organic material (so organic surfactant), and as well applicant identifies this also as a non-ionic surfactant (00117 of the specification).
Claims 11 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Verzwyvelt, in view of ‘891, Gubler article, ‘465, Staiti article and Livingston as applied to claims 6-8 above, and further in view of Cabasso et al (US 2004/0028976).
Claim 11-12: As to use of a viscosity control solvent and its amount and material,
Livingston further notes that solvents which can be used for dissolving the PBI compound can be DMAc, etc. but also can be mixtures that also include alcohols (note 0048). Livingston also notes that viscosity adjusters (enhancers) can be used, describing amounts of up to 10 wt% in the solution, but does not specifically provide using solvents for this purpose (note 0050).
Cabasso describes providing PBI compounds and dissolving in solvents such as N, N-dimethylacetamide (DMAc), etc. (0040) where it is also described how solvents that can dissolve can be DMAc and also lower alcohols such as methanol, ethanol and isopropanol (note 0051). The PBI compound can be mPBI (note 0011 formula).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Verzwyvelt, in view of ‘891, Gubler article, ‘465, Staiti article and Livingston to dissolve the PBI compound using a mixture of DMAc (amide solvent) and also alcohols such as methanol, ethanol, and isopropanol as suggested by Livingston and Cabasso with an expectation of predictably acceptable results, as Verzwyvelt provides how a PBI solution can be provided by dissolving a PBI based compound and solvent such as DMA/DMAc, Gubler article suggests to use mPBI, and Livingston indicates that for dissolving such compounds one can use DMA/DMAc and also alcohols in a mixture and Cabasso indicates that when dissolving PBI compound DMAc, and alcohols such as methanol, ethanol and isopropanol can be used. By using the additional ethanol, methanol or isopropanol, a viscosity control solvent as in claims 11 and 12 would be used. As to the amount of the viscosity control solvent, it would have been obvious to optimize the specific amount of each solvent used, giving an amount in the claimed range. Note MPEP 2144.05(II)(A): “Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955
The Examiner notes that the rejections above use the suggestion to optimize various amounts and values. In the specification as filed an Example and comparative Examples were provided, and in the declaration filed August 4, 2025, further examples and arguments as to criticality were provided. The Examiner has reviewed this, however, a showing of criticality commensurate in scope to what is claimed has not been made. Note MPEP 716.02(d). For example, (1) as to the drying temperature, when using Verzwyvelt, while applicant has one example with a drying temperature higher than 80 degrees C giving shrinkage, this example uses a specific amount, application type, solution, etc. and a showing is not made commensurate in scope with the entire claims, which could use different amounts, application type, and additional compounds such as surfactants and viscosity control solvents added, etc. (which changes would be expected to affect results, such as, for example, different solvents can have different solubility effects, etc.), so no criticality commensurate in scope with what is claimed has been shown. The August 2025 declaration does not provide further showings as to the drying temperature. (2) Furthermore as to the declaration of August 2025, it does not establish criticality commensurate in scope over the width of the claims. All of the tests appear to be using simply m-PBI in DMAC where the present claims allow additional material (such as viscosity control solvent and surfactant, note claim 6, 11, for example, which would change the composition and could affect results, as noted above), where the solution is at normal pressure (noting that the present claims would allow any pressure, where even with the pressure range deleted in claim 1, there is no limit on pressure), for example. It is not shown why the results applicant got with the specific m-PBI solution used would work with all possible solutions as claimed, where the previously used Tan reference, for example, would show that higher temperatures can be used in combination with higher pressures, for example, so evidencing against this. As well, note Livingston at 0088, Table 2, with DMAC, with high weight % of PBI at 80 degrees C. Additionally, the new references to Gubler article and ‘465 appear to contradict the results shown in applicant’s declaration, where Gubler article indicates providing 10 wt% mPBI (in the claimed range) in DMAC at a dissolving temperature of 60 degrees C (so results as desired outside the claimed temperature range), and ‘465 indicates approx. 10.7 wt% mPBI (in the claimed range) completely dissolved at temperatures in the range of 110-140 degrees C (so results as desired in and out of the claimed temperature range). Thus, the evidence of record does not support that there is criticality as to the claimed temperature range to get the claimed amount of mPBI in solution. This also shows that it is well known to achieve amounts of mPBI in DMAC solvent in the claimed ranges, and Gubler article would show the known use of this amount in the separator art. Additionally, Staiti article indicates using a temperature in the claimed range to give solubility it the range of 8-20 wt% described in paragraphs 23-29 is in fact known. (3) Furthermore, all testing is done as noted for a solution of mPBI and DMAC, and also not indicated what effects occur when other allowed materials present, such as in claim 6, 8 and 11, for example, where effects of surfactant and viscosity control solvent would need to be taken into account. Thus, the testing is not commensurate in scope with the range of materials claimed. A showing of criticality would therefore, not have been made.
Hwang, et al “Preparation of Polybenzimidazole-Based Membranes and Their Potential Applications in the Fuel Cell System”, describes the formulas of various PBI compounds, including oPBI (which corresponds that that described in Yuan article) (note schemes 3, 4, 5). “Technical Data Sheet Dimethylacetamide (DMAc)” notes the boiling point of DMAc as 166 degrees C (note page 1). Lu et al (US 2023/0275247) notes redox flow batteries (note 0001), which can use vanadium redox couple (note 0006, 0020), where a separator can be used which is a PBI based membrane (note 0013).
Response to Arguments
Applicant's arguments filed December 19, 2025 have been fully considered.
Note the adjustment to the rejections, with the removal of Yuan article and optionally Wensley and the addition of new references of Gubler article and CN ‘465 due to the amendments to the claims.
As to the arguments as to the previous 35 USC 103 rejections, claim 1 was amended to require using DMAC solvent, m-PBI as the PBI compound, and a solubility of 8-12 wt%. New references to Gubler article and ‘465 were cited as to the use of m-PBI with DMAC with the solubility claimed and the suggestion to provide the claimed temperatures is also made. The Examiner has detailed in paragraph 19 why the declaration/examples would not overcome the rejections. As to the argument that technical reasons were not provided as to why pressure, and use of other solvents would affect results, the Examiner disagrees. As to the use of different pressures, the Examiner cited Tan and Livingston, with Tan indicated higher temperatures can be used with higher pressures. As to using other solvents and surfactants, the claims indicate that other materials than that tested can be used (noting claims 6, 8 and 11), and thus a consideration of what effects would occur should be taken into account when testing. For example additional solvent could affect the amount of solubility of the mPBI if the solvent additionally also dissolves the mPBI. As to the rejections being based on use of o-PBI, with the amendment and new rejections, the Examiner has indicated why m-PBI would be used, noting the use of Gubler article. As to the 8-12 wt% solubility, the new references to Gubler article and ‘465 are cited. Therefore, the rejections above are maintained.
Conclusion
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/KATHERINE A BAREFORD/Primary Examiner, Art Unit 1718