Prosecution Insights
Last updated: April 19, 2026
Application No. 18/288,249

HOLLOW FIBER MEMBRANE AND MANUFACTURING METHOD THEREFOR

Non-Final OA §103§112
Filed
Oct 25, 2023
Examiner
MILLER-CRUZ, EKANDRA S.
Art Unit
1773
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Toray Industries, Inc.
OA Round
1 (Non-Final)
66%
Grant Probability
Favorable
1-2
OA Rounds
2y 7m
To Grant
99%
With Interview

Examiner Intelligence

Grants 66% — above average
66%
Career Allow Rate
217 granted / 331 resolved
+0.6% vs TC avg
Strong +52% interview lift
Without
With
+52.4%
Interview Lift
resolved cases with interview
Typical timeline
2y 7m
Avg Prosecution
32 currently pending
Career history
363
Total Applications
across all art units

Statute-Specific Performance

§101
1.7%
-38.3% vs TC avg
§103
44.8%
+4.8% vs TC avg
§102
16.5%
-23.5% vs TC avg
§112
26.9%
-13.1% vs TC avg
Black line = Tech Center average estimate • Based on career data from 331 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 Claims 1-19 are pending: Claims 1-4, 6-7 and 12 are rejected. Claims 5, 8-11 and 13 are objected Claims 14-19 have been withdrawn. Priority Acknowledgment is made of applicant’s claim for foreign priority under 35 U.S.C. 119 (a)-(d). The certified copy has been filed in parent Application No. JP 2021-075668 filed on 04/28/2022, JP 2021-108523 filed on 06/30/2021 and JP 2021-138656 filed on 08/27/2021. Election/Restrictions Claims 14-19 withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected group II, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 01/20/2026. 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. Claims 1-4, 6-7 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Iwai (US 2017/0157572). Regarding claim 1, Iwai teaches a hollow fiber membrane (hollow fiber membrane, see ¶170) comprising a layer of a spherical structure (spherical structure layer, see ¶142) of a resin (resin solution, see ¶187), wherein the layer of the spherical structure has a thickness L of 60 um or more and 500 um or less (thickness preferably between 50 um to 350 um, see ¶67 which overlaps with the claimed range). The examiner takes note of the fact that the prior art range of 50 – 350 um overlaps the claimed range of 60 – 500 um. Absent any additional and more specific information in the prior art, a prima facie case of obviousness exists. In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379 (Fed. Cir. 2003). MPEP 2144.05. With respect to the limitation, “the layer of the spherical structure has a first surface and a second surface, an average diameter Dan of the spherical structure in a region San of 10 x (n - 1) to 10 x n um from the first surface and an average diameter Dbn of the spherical structure in a region Sbn of 10 x (n - 1) to 10 x n um from the second surface satisfy a relation of Da1 > Db2, and a minimum value imin of a natural number i satisfying the following conditions (1) and (2) satisfies a relation of 3 ≤ imin ≤ (L - 20)/10, (1) Da1/Dai ≥1.1 (2) -0.3 pm Da1-Db2 0.3 pm provided that n is a natural number, and in the relation of 3 ≤ imin ≤ (L - 20)/10, a decimal point or less of (L - 20)/10 is truncated” and “wherein a relation of imin L x 0.75/10 is satisfied, provided that in the relation of imin L x 0.75/10, a decimal point or less of L x 0.75/10 is truncated”, example 6 discloses a membrane having diameter relationships: D1 = 2.58 um, D2 = 1.86 um, D3 = 1.96 um, D1/D3 = 1.32 and D3 - D2 = 0.10 um therefore example 6 demonstrates that the spherical relationships required by conditions (1) and (2) occur within the membrane; but Iwai does not disclose imin (or the depth) at these conditions as required by claims 1-2. Regarding claims 1-2, it would have been obvious to one ordinary skill in the art before the effective filing date of the invention to modify the membrane spherical diameter of Iwai by controlling routine spinning and cooling conditions, and adjusting these parameters to shift the transition deeper into the separation membrane would have been obvious by routine optimization with a reasonable expectation of success. Additionally, one of ordinary skill in the art would have had a reasonable expectation of success because Iwai already demonstrates the claimed diameter relationships within the membrane, and merely shifting the location at which these relationships occur within the membrane thickness does not produce a structurally distinct membrane. “[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.” See In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). Regarding claim 3, Iwai teaches the hollow fiber membrane according to claim 1, wherein a relation of 1.10 < Da1/Daimin < 4.00 is satisfied (i.e. D1/D3 1.32). Regarding claim 4, Iwai teaches the hollow fiber membrane according to claim 1,wherein a relation of 0.50 um < Db2< 2.00 um is satisfied (i.e. D2 = 1.86 um). Regarding claim 6, Iwai teaches the hollow fiber membrane according to claim 1,wherein the first surface is on a side of liquid to be filtered (the separation membrane is usually used by arranging the first surface to come into contact with liquid to be treated, see ¶33 and ¶36). Regarding claim 7, Iwai teaches the hollow fiber membrane according to claim 1,wherein the first surface is an outer surface of the hollow fiber membrane (this configuration is implied in ¶51). Regarding claim 12, Iwai teaches the hollow fiber membrane according to claim1, wherein the spherical structure comprises a polyvinylidene fluoride-based resin (see claim 14), a hydrophilic polymer (a polyhydric alcohol, see ¶44) is present on a surface and inside of the spherical structure (the polyhydric alcohol gets mixed with the resin, see ¶44 which implies this additive ends up throughout the membrane matric including pore surfaces therefore the limitation is met), and the hydrophilic polymer is contained in an amount of 1.0 parts by mass or more with respect to 100 parts by mass of the polyvinylidene fluoride-based resin (a polyhydric alcohol or a surfactant in a ratio of 50 mass % or less, see ¶44 which overlaps with the claimed range). The examiner takes note of the fact that the prior art range of 50 mass % or less overlaps the claimed range of 1.0 mass % or more. Absent any additional and more specific information in the prior art, a prima facie case of obviousness exists. In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379 (Fed. Cir. 2003). MPEP 2144.05. Allowable Subject Matter Claims 5, 8-11 and 13 would be allowable if rewritten to overcome the rejection(s) under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action and to include all of the limitations of the base claim and any intervening claims. Claims 5, 8-11 and 13 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. The following is a statement of reasons for the indication of allowable subject matter: Regarding claim 5, Iwai teaches the hollow fiber membrane according to claim 1. However, Iwai does not teach “wherein a relation of 1.00 ≤ Da1/Da2 ≤ 1.10 is satisfied” as required by claim 5. It would not have been obvious to one of ordinary skill in the art before the effective filing date to modify Iwai to arrive at the claimed range because Iwai, in fact, teaches away from having 1.00 ≤ Da1/Da2 ≤ 1.10 as it is demonstrated in Comparative Example 1, separation membranes that fall within this range have low water permeation performance and readily causing elevation of filtration resistance (Iwai, see ¶179). Regarding claim 13, Iwai teaches the membrane according to claim 12. It is noted in the background of Iwai, that sodium hypochlorite is used for sterilizing permeate or preventing biofouling of the separation membrane (Iwai, see ¶4). However, Iwai does not teach nor fairly suggest “wherein a percentage of a ratio P1/P0of P1 to P0 is 70% or less, where P1 is a ratio (mass%) of the hydrophilic polymer to the polyvinylidene fluoride-based resin after the hollow fiber membrane is immersed in a 3,000 ppm of aqueous sodium hypochlorite solution (pH 12.5) at 60oC for 30 hours, and PO is a ratio (mass%) of the hydrophilic polymer to the polyvinylidene fluoride-based resin before the immersion” as required by claim 13. There is no known benefit of incorporating the precise combination of elements to the separation membrane of Iwai. Regarding claim 8, Iwai teaches the hollow fiber membrane according to claim 1. However, Iwai does not teach nor fairly suggest “wherein when a throat diameter obtained by a pore network model analysis for the hollow fiber membrane is defined as a constriction diameter of a spherical structure gap, an average diameter dan of the constriction diameter of the spherical structure gap in the region San of 10 x (n - 1) to 10 x n um from the first surface, and an average diameter dbn of the constriction diameter of the spherical structure gap in the region Sbn of 10 x (n - 1) to 10 x n um from the second surface satisfy a relation of da1>db2, and a minimum value jmin of a natural number j satisfying the following conditions (1) and (2) satisfies a relation of 3 ≤ jmin ≤ (L - 20)/10, (1) da1/da2 ≥ 1.15 (2) da, - db2 ≤ 0.10 um provided that in the relation of 3 ≤ jmin ≤ (L - 20)/10, a decimal point or less of (L - 20)/10 is truncated” as required by claim 8. There is no known benefit of incorporating the precise combination of elements to the separation membrane of Iwai. Dependent claims 9-11 dependent from claim 8 therefore are also indicated allowable. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to EKANDRA S. MILLER-CRUZ whose telephone number is (571)270-7849. The examiner can normally be reached M-Th 7 am - 6 pm EST. 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, Benjamin L. Lebron can be reached at (571) 272-0475. 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. /EKANDRA S. MILLER-CRUZ/Primary Examiner, Art Unit 1773
Read full office action

Prosecution Timeline

Oct 25, 2023
Application Filed
Oct 25, 2023
Response after Non-Final Action
Mar 14, 2026
Non-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

1-2
Expected OA Rounds
66%
Grant Probability
99%
With Interview (+52.4%)
2y 7m
Median Time to Grant
Low
PTA Risk
Based on 331 resolved cases by this examiner. Grant probability derived from career allow rate.

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