Prosecution Insights
Last updated: April 19, 2026
Application No. 18/034,030

POLYOLEFIN MICROPOROUS MEMBRANE

Non-Final OA §103
Filed
Apr 26, 2023
Examiner
LYNCH, VICTORIA HOM
Art Unit
1724
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Asahi Kasei Battery Separator Corporation
OA Round
1 (Non-Final)
86%
Grant Probability
Favorable
1-2
OA Rounds
2y 10m
To Grant
96%
With Interview

Examiner Intelligence

Grants 86% — above average
86%
Career Allow Rate
698 granted / 807 resolved
+21.5% vs TC avg
Moderate +9% lift
Without
With
+9.1%
Interview Lift
resolved cases with interview
Typical timeline
2y 10m
Avg Prosecution
41 currently pending
Career history
848
Total Applications
across all art units

Statute-Specific Performance

§101
0.6%
-39.4% vs TC avg
§103
45.2%
+5.2% vs TC avg
§102
25.9%
-14.1% vs TC avg
§112
23.9%
-16.1% vs TC avg
Black line = Tech Center average estimate • Based on career data from 807 resolved cases

Office Action

§103
DETAILED ACTION Notice of Pre-AIA or AIA Status 1. The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Election/Restrictions 2. Applicant’s election without traverse of Species A (claims 17-28 which read on elected claims 1, 3-4, and 6-15 now cancelled) in the reply filed on 1/7/26 is acknowledged. Claim Rejections - 35 USC § 103 3. 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. 4. 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. 5. 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. 6. Claim(s) 17-20, and 24-28 is/are rejected under 35 U.S.C. 103 as being unpatentable over Sano et al. (US2012/0115008) as cited in IDS dated 1/25/24. Regarding claim 17, Sano discloses a polyolefin microporous membrane (abstract) comprising 50% by weight or more of a polyethylene([0067]), having: a membrane thickness of 1 µm to 30 µm (5 µm to 25 µm [0071]); an air permeability of 200 sec/100 cm3 or less (Gurley value preferably from 50 to 500 sec/100 cc [0073]); and a puncture strength of 220 gf or more(thrust resistance preferably 250 g or higher [0075], [0193]-[0194]), wherein the polyethylene has a crystallite size of 15.0 nm or greater and 28.0 nm or smaller(5 nm to 50 nm [0016]). Sano is explicitly silent to the claim ranges however “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); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05. Continuing with claim 17, Sano discloses when the separator cannot follow the volume change of the electrode and the porous structure of the separator cannot recover from a compressed state, a phenomenon in which a sufficient amount of electrolyte cannot be retained in the holes of the separator, that is, a liquid depletion phenomenon may occur([0009]). Sano discloses the liquid depletion prevention effect of the polyolefin microporous membrane and the separator for a non-aqueous secondary battery was evaluated by measuring the recovery ratio after pressurization ([0216]). Sano discloses the higher the recovery ratio after pressurization, the more excellent the liquid depletion prevention effect([0217]. Sano discloses the recovery ratio after pressurization was measured by pressurizing by a plate press machine at 40 MPa for 5 minutes, followed by releasing the pressure with this procedure repeated 5 times([0217]). Sano discloses the porosity after pressing of 30% or higher ( 0.52 * 0.83 ≈ 43%, Table 1, Example 5 with porosity 52% and recovery ratio after pressurization of 83%) but does not explicitly disclose a compression test conducted at a temperature of 70°C and a pressure of 8 MPa for a compression time of 3 minutes. However, given that the porosity after pressing of the prior art overlaps the presently claimed range, absent evidence to the contrary regarding the criticality of how a post-compression porosity is measured, it is the Examiner’s position that the porosity after pressing of Sano meets the presently claimed limitation. Regarding claim 18, Sano discloses having a porosity of 35% or higher( 0.52 * 0.83 ≈ 43%, Table 1, Example 5 with porosity 52% and recovery ratio after pressurization of 83%). Regarding claim 19, Sano discloses having a porosity of 40% or higher( 0.52 * 0.83 ≈ 43%, Table 1, Example 5 with porosity 52% and recovery ratio after pressurization of 83%) but does not explicitly disclose at 30°C in a pressurized state of 3 MPa. However, given that the porosity after pressing of the prior art overlaps the presently claimed range, absent evidence to the contrary regarding the criticality of how a post-compression porosity is measured, it is the Examiner’s position that the porosity after pressing of Sano meets the presently claimed limitation. Regarding claim 20, Sano discloses the content of a polyethylene component having a weight-average molecular weight (Mw) of 1,000,000 or more as measured by GPC is not less than 7% with respect to all eluted components measured by GPC([0019], [0173]-[0175]). Regarding claim 24, Sano discloses a separator, comprising the polyolefin microporous membrane according to claim 17[0021]); and an inorganic porous layer arranged on at least one surface of the polyolefin microporous membrane([0023]). Regarding claim 25, Sano discloses a separator, comprising the polyolefin microporous membrane according to claim 17([0021]); and a thermoplastic resin layer arranged on at least one surface of the polyolefin microporous membrane([0022]). Regarding claim 26, Sano discloses a separator, comprising the polyolefin microporous membrane according to claim 17([0021]); and at least one layer which is arranged on at least one surface of the polyolefin microporous membrane and selected from the group consisting of a multi-functional layer, an inorganic porous layer, and a thermoplastic resin layer([0022]-[0026]). Regarding claim 27, Sano discloses a nonaqueous secondary battery, comprising the polyolefin microporous membrane according to claim 17([0027]). Regarding claim 28, Sano discloses a nonaqueous secondary battery, comprising the separator according to claim 24([0027]). 7. Claim(s) 21 is/are rejected under 35 U.S.C. 103 as being unpatentable over Sano et al. (US2012/0115008) as cited in IDS dated 1/25/24 as applied to claim 17 above, and further in view of Nguyen et al. (US 2003/0104236). Regarding Claim 21, Sano discloses a high-density polyethylene having a density of 0.942 g/cm3([0019]). Sano discloses in the polyolefin microporous membrane, polyolefin flows at a high temperature and, thus, good shutdown properties can be obtained ([0037]) but does not explicitly disclose having a melt flow index (MI) of 1.0 or less. Nguyen teaches a microporous membrane ([0008]). Nguyen teaches the microporous membrane will consist of a blend of an aliphatic polyolefin and a thermoplastic olefin (TPO) elastomer([0009]). Nguyen teaches polyethylene refers preferably to a high-density polyethylene having a density (ASTM D792) ranging from 0.95 to 0.96 g/cm2, and a melt flow index (MFI, ASTM D1238, 190° C. per 2.16 kilograms) ranging from 0.38 to 0.42 dg/minutes ([0010]). It would have been obvious to one of ordinary skill in the art to use as the polyethylene of Sano, one having a melt flow index (MI) of 1.0 or less as taught by Nguyen, since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. MPEP 2144.07 8. Claim(s) 22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Sano et al. (US2012/0115008) as cited in IDS dated 1/25/24 as applied to claim 17 above, and further in view of Fukunaga et al. (WO2018/216819) with citations from equivalent (US2020/0176742). Regarding claim 22, Sano discloses the heat shrinkage ratio of a polyolefin microporous membrane of the present invention at 105° C. is preferably from 5 to 40% ([0078]) but does not explicitly disclose having a TD heat shrinkage of 20% or less at 120°C. Fukunaga teaches a polyolefin microporous membrane, a separator for electricity storage devices, and an electricity storage device ([0001]). Fukunaga teaches the microporous membrane, wherein the polyolefin resin is polyethylene or a mixture of polyethylene and polypropylene([0017]). Fukunaga teaches the microporous membrane, wherein a thermal shrinkage in TD at 120° C. is −2% or more and 5% or less([0017]). It would have been obvious to one of ordinary skill in the art to use as the polyethylene of Sano, one having a TD heat shrinkage of 20% or less at 120°C as taught by Fukunaga as obvious to try choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success. See MPEP 2143. 9. Claim(s) 23 is/are rejected under 35 U.S.C. 103 as being unpatentable over Sano et al. (US2012/0115008) as cited in IDS dated 1/25/24 as applied to claim 17 above, and further in view of Iidani et al. (US2009/0186280). Regarding claim 23, Sano discloses from the viewpoint of the resistance to the breakage when a separator is wound when producing a non-aqueous secondary battery, the tensile strength of separator for a non-aqueous secondary battery is preferably 10 N or higher([0108]) but does not explicitly disclose a ratio (MD/TD tensile strength ratio) of a tensile strength in the longitudinal direction (MD) to a tensile strength in the width direction (TD) is 0.5 to 2.0. Iidani teaches polyolefin microporous membrane (title). Iidani teaches tensile strengths in the length direction (MD tensile strength) and the width direction (TD tensile strength) of 30 MPa or more each ([0026]). Iidani teaches a ratio (MD/TD tensile strength ratio) of a tensile strength in the longitudinal direction (MD) to a tensile strength in the width direction (TD) is 0.5 to 2.0 (Table 2, examples 5-6). It would have been obvious to one of ordinary skill in the art to provide the polyolefin microporous membrane of Sano with a ratio (MD/TD tensile strength ratio) of a tensile strength in the longitudinal direction (MD) to a tensile strength in the width direction (TD) is 0.5 to 2.0 as taught by Iidani as obvious to try choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success. See MPEP 2143. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to VICTORIA HOM LYNCH whose telephone number is (571)272-0489. The examiner can normally be reached 7:30 AM - 4:30 PM EST M-F. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Miriam Stagg can be reached at 571-270-5256. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /VICTORIA H LYNCH/Primary Examiner, Art Unit 1724
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Prosecution Timeline

Apr 26, 2023
Application Filed
Feb 03, 2026
Non-Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
86%
Grant Probability
96%
With Interview (+9.1%)
2y 10m
Median Time to Grant
Low
PTA Risk
Based on 807 resolved cases by this examiner. Grant probability derived from career allow rate.

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