Prosecution Insights
Last updated: April 19, 2026
Application No. 17/926,415

FILTER MEDIUM FOR AIR FILTERS AND METHOD FOR PRODUCING SAME

Final Rejection §103§112
Filed
Nov 18, 2022
Examiner
DAVIS, SHENG HAN
Art Unit
1732
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Hokuetsu Corporation
OA Round
2 (Final)
66%
Grant Probability
Favorable
3-4
OA Rounds
3y 3m
To Grant
99%
With Interview

Examiner Intelligence

Grants 66% — above average
66%
Career Allow Rate
701 granted / 1064 resolved
+0.9% vs TC avg
Strong +36% interview lift
Without
With
+35.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 3m
Avg Prosecution
67 currently pending
Career history
1131
Total Applications
across all art units

Statute-Specific Performance

§101
0.1%
-39.9% vs TC avg
§103
62.6%
+22.6% vs TC avg
§102
6.9%
-33.1% vs TC avg
§112
20.8%
-19.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1064 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 . Claim Status The claims are newly amended. Response to Arguments Applicant’s arguments, see pages 4-7, filed 12/1/25, with respect to the rejection(s) of claim(s) 1, 3-7 under the non-final have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of the references below. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claim 7 is rejected 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. Claim 7 depends on canceled Claim 2. This claim will be treated as depending on Claim 1 unless amended. Claim Rejections - 35 USC § 103 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. Claim(s) 1, 6 is/are rejected under 35 U.S.C. 103 as being unpatentable over Yamamoto (JP2017/042762) and in view of Nokai (JP H 615126) and in view of Soyama (JP H 10156116) and in view of Smith (WO 2018/175556). The Examiner has provided a machine translation of JP2017/042762 and JP H 615126. The citation of the prior art in this rejection refers to the machine translation. For the product claim of Claim 1, the claims include features in the preamble, which are treated by the courts as such: A preamble is generally not accorded any patentable weight where it merely recites the purpose of a process or the intended use of a structure, and where the body of the claim does not depend on the preamble for completeness but, instead, the process steps or structural limitations are able to stand alone. See In re Hirao, 535 F.2d 67, 190 USPQ 15 (CCPA 1976) and Kropa v. Robie, 187 F.2d 150, 152, 88 USPQ 478, 481 (CCPA 1951). Nonetheless, these features are taught by the reference. Also, the method steps of Claim 6 are also treated here. Yamamoto describes a filter medium useable for an air filter (para. 1) composed of glass fibers (para. 3). The filter is made by processing wet paper (para. 12), in a slurry (para. 24). A wet paper slurry is impregnated with a liquid solution (para. 28). This can be considered to meet the “wet-laid” feature of Claim 1, line 1. As to the composition, the filter may be a mixture of binder resin and a fluorosurfactant (para. 9) in water (para. 21, 22). The water repellency of the filter is important (para. 8) and that water-repellent agents may be used to impart water repellency to improve the PF value of the filter medium (para. 17). In the examples, Yamamoto teaches that the filter can be made up of an acrylic resin emulsion, a fluorine-based surfactant and a binder (examples 1, 2), where the fluorine-based composition is a water repellent compound (para. 30). The product is dried (para. 12, 26). As to the features of Claim 1, Yamamoto describes use of an acrylic resin emulsion (para. 29). This can be considered the binder. This is combined with a fluorine-based water repellent (para. 29). Both of these are then combined with a fluorine-based surfactant (para. 29). Yamamoto does not specifically describe that the fluorine-based water repellent is a perfluoroalkyl group-containing resin or that the binder, the fluororesin and the surfactant are cationic or that the solid content mass ratio of the fluororesin to the surfactant is 30/70 to 80/20. As to the cationic features, the specification of this application explains that cationic features of the composition. Specifically, the disclosure states that the term “cationic” means that either the compound is cationic itself or “the emulsifier or the like is cationic” (published specification, para. 27, 29) and that the surfactant used can be nonionic (published specification, para. 28), as long as the filter medium includes a cationic surfactant. On this last features, this is taught by Smith (below). As to the use of use of a perfluoroalkyl group-containing resin, Yamamoto describes use of a fluorine-based water repellent, but not use of a perfluoroalkyl group-containing resin. Nokai describes an air filter (title) obtained by wet paper making (abstract). The method includes combining a binder element with a a fluorien-containing resin (see para. 21). As to the water repellent features, Nokai teaches that use of a perfluoroalkyl group-containing resin is effective as a fluorine-containing resin for use with the air filter (see page 5, lines 23-24). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to employ a perfluoroalkyl group-containing resin as the water repellent compound of Yamamoto because Nokai explains that perfluoroalkyl group-containing resin is an effective water repellent for use in air filtration manufacture. As to the solid content mass ratio of the fluororesin to the surfactant, Soyama describes an air filter media for use with air filters (title) that is made using a fluorine-based surfactant (para. 11, para. 1) that is added to the air filter slurry along with a binder and a fluorine-based water repellent compound (example 1). The ratio of the fluorine-based water repellent compound to the weight of a fluorine-based surfactant can be about 3.2% (see example 1, calculated from 0.16%: 0.05%). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to employ the water repellent compound in an amount that is about 3.2% to the weight of a fluorine-based surfactant, as taught by Soyama for use with the air filter media of Yamamoto, Nokai and Smith because this ratio is known to produce predictable and effective results for use in an air filter. Yamamoto describes use of a surfactant (examples 1, 2), but does not describe use of a cationic surfactant. Smith describes a filter material (title) that is hydrophobic (abstract, para. 85) for use in air filtration (para. 115). The filter is made-up of glass fibers (para. 44, 45), a binder material (para. 60), which can include acrylates (para. 61). The compounds can include a variety of resins (para. 79). As to the surfactant, Smith teaches that the surfactant can function as the wetting agent and can be used to modify the hydrophilicity of the layers in the filter (para. 96). To do this, Smith explains that various wetting agents can be employed to adjust the hydrophobicity, which includes use of a cationic surfactant (para. 96). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to employ cationic surfactants, as the surfactant of Yamamoto because Smith teaches these surfactants are known for use to modify the hydrophilicity of the layers in the filter and adjust the hydrophobicity of the air filter. Claim(s) 3, 5 and 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Yamamoto, Nokai, Soyama and Smith as applied to claim 1 above, and further in view of Sato (JP 2011/062643). The references do not disclose how much of the filter medium is added to the filter. Sato describes a filter medium for use in an air filter (title). The filter medium includes a fluorine-containing resin (page 2, “description”, para. 2). This binder resin is used with a water repellent agent in order to bind the filter fibers and give them strength (page 2, “description”, para. 4). In example 1, Sato teaches that the filter medium is added to the air filter, such that the solid content added to the filter is about 5.4 mass% relative to the filter medium and the filter (see example 1). A prima facie case of obviousness exists where the claimed ranges and prior art ranges overlap or are close enough that one skilled in the art would have expected them to have the same properties. See 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 include filter medium with the filter in an amount of 5.4 mass%, as taught by Sato for use with the filter medium and filter composition of Yamamoto, Nokai, Soyama and Smith because this amount of filter medium added is known to lead to predictable and expected results. Claim(s) 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Yamamoto, Nokai, Soyama and Smith as applied to claim 1 above, and further in view of Sato (WO 2014/171165), Sato II. Yamamoto teaches that the filter has a glass fiber that has an average diameter of 0.65 micrometers, combined with a glass fiber have an average diameter of 2.7 micrometers, combined with glass fibers with an average diameter of 6 micrometers (para. 28). Yamamoto does not teach that some of these glass fibers are glass wool. Sato II teaches an air filter material (title) that is made of glass fibers (abstract). The wet non-woven fabric includes a fluorine resin and a surface active agent (abstract) as well as surfactant (page 4, para. 34-36). Sato II teaches that a solids content has a mass ratio of between 0.5-20 parts by mass of the fluororesin and the surfactant (page 4, lines 41-45). Sato teaches that in addition to the glass fiber and the binder fibers, various other fibers can be used, such as glass wool fibers (page 5, para. 6). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to include glass wool fibers in-place of some of the glass fibers of Yamamoto, Nokai, Soyama and Smith, as taught by Sato II because Sato II explains that some of the glass fibers can be substituted with glass wool fibers. 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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to SHENG HAN DAVIS whose telephone number is (571)270-5823. The examiner can normally be reached 9-5:30. 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, Fung Coris can be reached at 571-270-5713. 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. /SHENG H DAVIS/Primary Examiner, Art Unit 1732 January 22, 2026
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Prosecution Timeline

Nov 18, 2022
Application Filed
May 25, 2025
Non-Final Rejection — §103, §112
Dec 01, 2025
Response Filed
Jan 22, 2026
Final Rejection — §103, §112 (current)

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Prosecution Projections

3-4
Expected OA Rounds
66%
Grant Probability
99%
With Interview (+35.9%)
3y 3m
Median Time to Grant
Moderate
PTA Risk
Based on 1064 resolved cases by this examiner. Grant probability derived from career allow rate.

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