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. Priority Acknowledgment is made of applicant's claim for foreign priority based on an application filed in Japan on February 04, 2021 . It is noted, however, that applicant has not filed a certified copy of the 2021-016674 application as required by 37 CFR 1.55. Election/Restrictions Applicant’s election of Invention I, claims 1–5, 7–14, 19 and 20 in the reply filed on December 02, 2025 is acknowledged. Because applicant did not distinctly and specifically point out the supposed errors in the restriction requirement, the election has been treated as an election without traverse (MPEP § 818.01(a)). Claim Rejections - 35 USC § 112(d) 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 s 2 , 9, 10 and 12 are 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. 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 2 recites: 2. The air filter medium according to claim 1, wherein the fluororesin porous membrane has a thickness of 50 µm or less . Emphasis added. Claim 2 fails to further limit the scope of claim 1, because claim 1 requires that the f luororesin porous membrane has a thickness of 10 µm or more, and claim 2 broadens the scope of this range by saying that the thickness is 5 0 µm or less (which potentially includes values below 10 µm). To overcome this rejection, claim 2 could be amended to read: 2. The air filter medium according to claim 1, wherein the fluororesin porous membrane has a thickness of 50 µm or less and 10 µm or more . Claims 9, 10 and 12 are rejected under 35 U.S.C. 112(d) because they depend from claim 2. Claim Rejections - 35 USC §§ 102 or 103 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. 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. Claim s 1 , 2, 4, 5, 10, 12, 14, 19 and 20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Inui et al., JP 2020 0 11215 A or in the alternative under 35 U.S.C. 103 as being unpatentable over Inui . Note that Inui et al., US 2021/0260516 A1 is cited as an English translation because it is in the same patent family as Inui e t al., JP 2020 0 11215 A . Regarding claim 1 , Inui teaches an air filter medium, which reads on the claimed “air filter medium.” See Inui, Example 4, Fig. 3, [0136]. The air filter medium comprises a first fluororesin porous film 31 , which reads on the “fluororesin porous membrane” and an upstream air-permeable supporting member 21 stacked on an upstream side of the first fluororesin porous film 31 , which reads on the claimed “supporting member stacked on at least one side of the fluororesin porous membrane.” See Inui, Example 4, [0136]. The air filter medium has an initial pressure loss of 56 Pa ( see Inui, Example 4, Table 1, p. 12) with initial permeability (i.e., initial pressure loss) being measured when air is passed through the air filter medium at a flow velocity of 5.3 cm/s ( id . at [0033]). The pressure loss of 56 Pa describes the pressure loss of the first fluororesin porous film 31 because the pressure loss of the other two layers of the air filter medium (air-permeable supporting members 21, 22 ) is substantially zero. See Inui, Fig. 3, [0105]. The prior art value of an initial pressure loss of 56 Pa measured at a flow velocity of 5.3 cm/s is within the claimed range of “a pressure loss of 80 Pa or less when air is passed at a flow rate of 5.3 cm/s.” With respect to the limitation—“the fluororesin porous membrane has a PF of 20 or more, the PF being determined from a formula P F={-log((100-collection efficiency (%))/100)}/(pressure loss (PA)/1000) determined from NaCl particles having a particle size of 0.1 µm”— Inui teaches that the air filter medium has an initial value of PF of 34.1 measured with the same formula as claimed, except that collection efficiency is determined using NaCl particles with a particle size of 0.3 µm instead of 0.1 µm as claimed. See Inui, Example 4, Table 1, p. 12 , [0013]. T he PF value of 34.1 describes the PF value of the first fluororesin porous film 31 because it is the layer within the air filter medium that primarily provides filtration capability as the other two layers layers (air-permeable supporting members 21, 22 ) are provided primarily for structural support, with collection efficiencies substantially zero. Id . at Fig. 3, [0105]. The claimed “PF” value is a function of the “fluororesin porous membrane” because it describes the relationship between collection efficiency and pressure loss, measured when the fluororesin membrane operates during filtration. The claimed “air filter medium” and “fluororesin porous membrane” are substantially identical in structure as the air filter medium and first fluororesin porous film 31 of Inui , as explained in this rejection of claim 1. Therefore, the fluororesin porous film 31 of Inui is presumed to exhibit a PF value of 20 or more determined from the formula PF={-log((100-collection efficiency (%))/100)}/(pressure loss (PA)/1000) determined from NaCl particles having a particle size of 0.1 µm , as claimed , because the porous film 31 has substantially the same structure as the claimed “fluororesin porous membrane . ” See MPEP 2112.01, subsection I (when the structure recited in the reference is substantially identical to that of the claims, claimed properties or functions are presumed to be inherent) . Also, the Examiner has a sound basis for believing that the first fluororesin porous film 31 has an initial PF value that is within the claimed PF value of 20 or more, because the first fluororesin porous film 31 has an initial PF value of 34.1 measured with the same formula as claimed, except determined using slightly larger NaCl particles (0.3 µm vs. 0.1 µm). See Inui, Example 4, Table 1, p. 12, [0013] . Therefore, the applicant has the burden of showing that t he filter medium of Inui does not necessarily or inherently possess the claimed PF value, so as to either anticipate or render obvious claim 1. See MPEP 2112, subsection V (once a reference teaching a product appearing to be substantially identical is made as the basis of a rejection, and the examiner presents evidence or reasoning to show inherency, the burden of production shifts to the applicant). The first fluororesin porous film 31 has a thickness of 38.6 µm, which is within the claimed range of 10 µm or more. See Inui, Example 4, Table 1, p. 12. The air filter medium has a polyalphaolefin (PAO) dust-holding capacity of 27.6 g/m 2 when air containing the PAO particles is continuous passed through the first fluororesin porous film at a flow rate of 5.3 cm/s and pressure loss increases by 250 Pa. See Inui, Example 4, Table 1, p. 12 , [0014] . The prior art value of 27.6 g/m 2 is within the claimed range of 15.0 g/m 2 or more. Regarding claim 2 , Inui teaches that the first fluororesin porous film (the “fluororesin porous membrane”) has a thickness of 38.6 µm, which is within the claimed range of 50 µm or less. See Inui, Example 4, Table 1, p. 12. Regarding claim s 4 and 10 , Inui teaches that the first fluororesin porous film 31 (the “fluororesin porous membrane”) contains a fibrillatable polytetrafluoroethylene (the “ fibrillatable polytetrafluoroethylene ”), a non-fibril-forming non-melting-processable component (the “non-fibrillatable non-melt-fabricable component”) and a non-fibril-forming hot-melt-processable component having a melting point lower than 320°C (the “non-fibrillatable melt-fabricable component having a melting point of lower than 320°C ”). See Inui [0020]. Regarding claim s 5 , 12 and 14 , Inui teaches that the first fluororesin porous film 31 (the “fluororesin porous membrane”) contains a modified polytetrafluoroethylene. See Inui [0054], [0057]. Regarding claim 19 , Inui teaches that the air filter medium has substantially the same structure as the air filter medium described in claim 19, as explained in the rejection of claim 1 above. The limitations of claim 19 describe the method of manufacturing the air filter medium, rather than its structure. These limitations fail to patentably distinguish the air filter medium of claim 19 over the air filter medium of Inui . See MPEP 2113, subsection I (the patentability of a product does not depend on its method of production unless the process steps imply structure). Regarding claim 20 , Inui teaches that the air filter medium comprises a shape including mountain folds (one being a “mountain fold portion”) and valley folds (one being a “valley fold portion”). See Inui [0125]. T he air filter medium is presumed to exhibit the claimed properties of— “ when air containing polyalphaolefin particles having a number median diameter of 0.25 um is continuously passed through the pleated mask filter medium at a flow rate of 85 L/min to apply a load of 200 mg of the polyalphaolefin particles, the pleated mask filter medium has a pressure loss of 120 Pa or less when air is passed at a flow rate of 40 L/min ”—because the air filter medium of Inui has substantially the same structure as the claimed “air filter medium.” See MPEP 2112.01, subsection I (when the structure recited in the reference is substantially identical to that of the claims, claimed properties or functions are presumed to be inherent). With respect to the limitations describing that the air filter medium is produced by the method according to claim 6, the air filter medium has substantially the same structure as the air filter medium described in claim 20 , as explained above. The limitations describing the process steps of making the air filter medium fail to patentably distinguish the air filter medium of claim 20 over the air filter medium of Inui because there is no evidence that the method steps of claim 20 result in a different structure than the filter medium of claim 20 . See MPEP 2113, subsection I (the patentability of a product does not depend on its method of production unless the process steps imply structure). Claim Rejections - 35 USC § 103 Claim s 3 , 9, 11 and 13 are rejected under 35 U.S.C. 103 as being unpatentable over Inui et al., JP 2020 0 11215 A in view of Sawada et al., US 2013/0267621 A1 . Note that Inui et al., US 2021/0260516 A1 is cited as an English translation because it is in the same patent family as Inui e t al., JP 2020 0 11215 A . Regarding claim s 3 and 9 , Inui teaches the limitations of claim s 1 and 2 , as explained above. Inui differs from claim s 3 and 9 because it is silent as to the coefficient of variation of pressure loss of the air filter medium. Therefore, the reference fails to provide enough information to teach the air filter medium has a coefficient of variation of pressure loss of 6.0 or less. But Sawada teaches that the coefficient of variation of pressure loss of a fluororesin membrane of an air filter is result effective because it impacts the variation in pressure loss across the membrane, which impacts filtration performance. See Sawada [0060], [0070]. It would have been obvious to use routine experimentation to determine the optimal coefficient of variation of pressure loss of the air filter medium of Inui to optimize the variation in pressure loss across the membrane . See MPEP 2144.05, subsection II (where 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). Regarding claim 11 , Inui teaches that the first fluororesin porous film 31 (the “fluororesin porous membrane”) contains a fibrillatable polytetrafluoroethylene (the “fibrillatable polytetrafluoroethylene”), a non-fibril-forming non-melting-processable component (the “non-fibrillatable non-melt-fabricable component”) and a non-fibril-forming hot-melt-processable component having a melting point lower than 320°C (the “non-fibrillatable melt-fabricable component having a melting point of lower than 320°C”). See Inui [0020]. Regarding claim 13 , Inui teaches that the first fluororesin porous film 31 (the “fluororesin porous membrane”) contains a modified polytetrafluoroethylene. See Inui [0054], [0057]. Claim s 7 and 8 are rejected under 35 U.S.C. 103 as being unpatentable over Inui et al., JP 2020 0 11215 A in view of Uchiyama et al., US 2015/0013295 A1 . Note that Inui et al., US 2021/0260516 A1 is cited as an English translation because it is in the same patent family as Inui e t al., JP 2020 0 11215 A . Regarding claim 7 , Inui teaches the limitations of claim 1, as explained above. Inui differs from claim 7 because it is silent as to the air filter medium being a “ mask filter medium ,” as claimed. But Inui teaches that the air filter medium can be used in various applications, such as ultra low penetration air filters for producing semiconductors (i.e., clean rooms) and filters for vacuum cleaners. See Inui [0119]. With this in mind, Uchiyama teaches a filter medium comprising a porous fluororesin membrane and an air-permeable support member , where the filter medium is used in various applications including a clean room, vacuum cleaner filter or mask. See Uchiyama [0059], [0079]. It would have been obvious to use the air filter medium of Inui in a mask because this is a suitable application for air filter media with a similar configuration as the air filter medium of Inui . Regarding claim 8 , Inui teaches the air filter medium can be pleated. See Inui [0125]. The air filter medium is presumed to exhibit the claimed properties of— “ when air containing polyalphaolefin particles having a number median diameter of 0.25 um is continuously passed through the pleated mask filter medium at a flow rate of 85 L/min to apply a load of 200 mg of the polyalphaolefin particles, the pleated mask filter medium has a pressure loss of 120 Pa or less when air is passed at a flow rate of 40 L/min ”—because the air filter medium of Inui has substantially the same structure as the claimed “air filter medium.” See MPEP 2112.01, subsection I (when the structure recited in the reference is substantially identical to that of the claims, claimed properties or functions are presumed to be inherent). Inui differs from claim 8 because it is silent as to the air filter medium being a “mask filter medium,” as claimed. But Inui teaches that the air filter medium can be used in various applications, such as ultra low penetration air filters for producing semiconductors (i.e., clean rooms) and filters for vacuum cleaners. See Inui [0119]. With this in mind, Uchiyama teaches a filter medium comprising a porous fluororesin membrane and an air-permeable support member, where the filter medium is used in various applications including a clean room, vacuum cleaner filter or mask. See Uchiyama [0059], [0079]. It would have been obvious to use the air filter medium of Inui in a mask because this is a suitable application for air filter media with a similar configuration as the air filter medium of Inui . Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to FILLIN "Examiner name" \* MERGEFORMAT T. BENNETT MCKENZIE whose telephone number is FILLIN "Phone number" \* MERGEFORMAT (571)270-5327 . 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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. FILLIN "Examiner Stamp" \* MERGEFORMAT T. BENNETT MCKENZIE Primary Examiner Art Unit 1776 /T. BENNETT MCKENZIE/ Primary Examiner, Art Unit 1776