Prosecution Insights
Last updated: April 19, 2026
Application No. 18/280,227

HEAT STABILIZED MEMBRANE

Final Rejection §103§112
Filed
Sep 03, 2023
Examiner
DAVIS, ZACHARY M
Art Unit
1783
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Celgard LLC
OA Round
2 (Final)
69%
Grant Probability
Favorable
3-4
OA Rounds
2y 9m
To Grant
99%
With Interview

Examiner Intelligence

Grants 69% — above average
69%
Career Allow Rate
243 granted / 351 resolved
+4.2% vs TC avg
Strong +31% interview lift
Without
With
+31.1%
Interview Lift
resolved cases with interview
Typical timeline
2y 9m
Avg Prosecution
17 currently pending
Career history
368
Total Applications
across all art units

Statute-Specific Performance

§101
0.1%
-39.9% vs TC avg
§103
54.1%
+14.1% vs TC avg
§102
14.8%
-25.2% vs TC avg
§112
21.9%
-18.1% vs TC avg
Black line = Tech Center average estimate • Based on career data from 351 resolved cases

Office Action

§103 §112
DETAILED ACTION 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 . 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 text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. Status of Claims Claims 26-30, 34, 36-40, and 42-50 are pending. Claim Rejections - 35 USC § 103 Claim(s) 26-30, 36-40, and 44-50 is/are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Pre-grant Publication 2014/0127492 to Stokes et al. cited in previous Office action (herein Stokes) in view of U.S. Pre-grant Publication 2023/0056490 to Sakakibara et al. cited in previous Office action (herein Sakakibara) and Japanese Publication JP 2010-036355 to Sakakibara et al. cited in previous Office action (herein Ameyama, the second named inventor, see machine translation). Regarding claims 26-30, 34, and 36-38, Stokes teaches a microporous membrane (abstract) comprising a polyolefin resin and made via a dry stretching process wherein a film is uniaxially stretched or biaxially stretched (paragraph 0012). Stokes teaches that the microporous membrane can be used in various end use application such as garments (paragraph 0020) or battery separators (paragraph 0105). Stokes teaches that the polyolefin in the microporous membrane can be a homopolymer or a copolymer (paragraph 0010) or combinations thereof (paragraph 0026). Stokes is silent as to a terpolymer being present, a secondary antioxidant being present, or the oxygen induction time of the membrane. Regarding the terpolymer, Ameyama teaches a microporous membrane for a battery separator (paragraph 0001) wherein the membrane comprises a polyolefin resin which can be homopolymers, copolymers, and terpolymers of propylene and ethylene or mixtures thereof (paragraphs 0013-0014). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the polyolefin of Stokes to include the terpolymers of Ameyama because it is known in the art as being suitable for the intended purpose. See MPEP 2144.07. Regarding the secondary antioxidant, Sakakibara teaches a microporous membrane (abstract) comprising polyethylene or polypropylene (paragraph 0082) that is used as a separator for a lithium-ion secondary cell (paragraph 0072). Sakakibara teaches that the membrane comprises one or more secondary antioxidants (paragraph 0127) in an amount of 100 ppm to 1 wt% (paragraph 0129) which overlaps the claimed range. It has been held that obviousness exists where the claimed ranges overlap or lie inside ranges disclosed by the prior art. MPEP 2144.05 (I). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the microporous membrane of Stokes to include the secondary antioxidants of Sakakibara because it is advantageous for strength, optical characteristics, and foreign matter removal characteristics (paragraph 0128). Regarding the oxygen induction time, Figure 3 of the instant specification discloses that the presence of an antioxidant or the use of a blend of polymers results in a microporous membrane that achieves the claimed oxygen induction times (the comparative example has a single polymer and no antioxidant while the inventive examples have both). Therefore, one of ordinary skill in the art would reasonably expect the microporous membrane of Stokes as modified according to Sakakibara and Ameyama to achieve the claimed oxygen induction times. Regarding claims 39-40, Stokes, Sakakibara, and Ameyama teach all the limitations of claim 26 as discussed above. As discussed above, Stokes teaches that the microporous membrane can be uniaxially stretched or biaxially stretched (paragraph 0012). Regarding claim 44, Stokes, Sakakibara, and Ameyama teach all the limitations of claim 26 as discussed above. Stokes teaches that the microporous membrane can be laminated to a non-woven material, mesh, and/or fabric (paragraphs 0059-0091). Regarding claim 45, Stokes, Sakakibara, and Ameyama teach all the limitations of claim 44 as discussed above. Stokes teaches that the laminate including the microporous membrane can have at least two layers (paragraphs 0059-0091). Regarding claims 46-49, Stokes, Sakakibara, and Ameyama teach all the limitations of claims 26 and 44 as discussed above. Stokes teaches that the microporous membrane can be used in applications requiring waterproof and breathability performance such as outerwear, disposable garments, and garments or items in medical-related applications (paragraph 0020). One of ordinary skill in the art would reasonably consider outerwear and garments or items in medical-related applications to meet the limitation of being personal protective equipment, i.e. outerwear protects one from environmental conditions and medical items and garments protect the wearer from contamination. Regarding claim 50, Stokes, Sakakibara, and Ameyama teach all the limitations of claim 26 as discussed above. Stokes teaches that films 60 inches or wider can be used to make the membrane (paragraph 0058). Claim(s) 42 and 43 is/are rejected under 35 U.S.C. 103 as being unpatentable over Stokes, Sakakibara, and Ameyama as applied above and in further view of WIPO Publication WO 2018/017944 to Lane et al. cited in previous Office action (herein Lane). Regarding claims 42 and 43, Stokes, Sakakibara, and Ameyama teach all the limitations of claims 26 as discussed above. Stokes teaches that the microporous membrane can receive a coating (paragraph 0107). Stokes is silent as to the coating containing an antioxidant. Lane teaches a coating for a porous substrate such as a battery separator (abstract) wherein the coating can include antioxidants (page 5, line 14). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the coating of Stokes to be the coating of Lane because it would improve the safety and performance of a battery in which the membrane was used (page 5, lines 1-2). Response to Amendment In view of Applicant’s amendments filed 5 March 2026, previous rejections under 35 U.S.C. 112(b) are hereby withdrawn. Applicant's arguments filed 5 March 2026 have been fully considered but they are not persuasive. Applicant argues that impermissible hindsight reasoning was used and that there would be no reasonable expectation of success in arriving at the claimed invention (Remarks, pages 5-6). In response to applicant's argument that the examiner's conclusion of obviousness is based upon improper hindsight reasoning, it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. In the instant case, the motivation to modify Stokes to include the secondary antioxidant of Sakakibara was found in Sakakibara, and the motivation to modify Stokes to include the terpolymer of Ameyama does not rely on the disclosure of the instant application. The fact that the membrane of Stokes as modified according to Sakakibara and Ameyama has the claimed oxygen induction time is not proof of hindsight reasoning. The recognition of latent properties not discussed in the prior art does not rebut a prima facie case of obviousness. See MPEP 2145(II). Applicant argues that the claimed polymer blends and the presence of a secondary antioxidant is critical to achieving the claimed oxygen induction time and points to the inventive examples and comparative example as evidence (Remarks, pages 6-9). The comparative example disclosed in the instant specification contains neither a blend of polymers nor a secondary antioxidant while the inventive examples contain both. Therefore, one is unable to ascertain whether it is in fact the presence of both or just the polymer blend or secondary antioxidant that is responsible of achieving the desired oxygen induction time. Furthermore, the amounts of secondary antioxidant of the inventive examples is not commensurate in scope with the claimed range. Therefore, no determination of the criticality of the claimed invention can be made. Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Contact Information Any inquiry concerning this communication or earlier communications from the examiner should be directed to ZACHARY M DAVIS whose telephone number is (571)272-6957. The examiner can normally be reached M-F 7-4:30, off 2nd Friday. 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, Maria V Ewald can be reached at 571-272-8519. 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. /ZACHARY M DAVIS/Primary Examiner, Art Unit 1783
Read full office action

Prosecution Timeline

Sep 03, 2023
Application Filed
Dec 18, 2025
Non-Final Rejection — §103, §112
Mar 05, 2026
Response Filed
Mar 09, 2026
Final Rejection — §103, §112 (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

3-4
Expected OA Rounds
69%
Grant Probability
99%
With Interview (+31.1%)
2y 9m
Median Time to Grant
Moderate
PTA Risk
Based on 351 resolved cases by this examiner. Grant probability derived from career allow rate.

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