Prosecution Insights
Last updated: April 19, 2026
Application No. 18/576,903

Semipermeable Membrane

Non-Final OA §103§112
Filed
Jan 05, 2024
Examiner
PERRIN, CLARE M
Art Unit
1779
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Kaneka Corporation
OA Round
1 (Non-Final)
67%
Grant Probability
Favorable
1-2
OA Rounds
2y 11m
To Grant
99%
With Interview

Examiner Intelligence

Grants 67% — above average
67%
Career Allow Rate
492 granted / 733 resolved
+2.1% vs TC avg
Strong +43% interview lift
Without
With
+42.9%
Interview Lift
resolved cases with interview
Typical timeline
2y 11m
Avg Prosecution
44 currently pending
Career history
777
Total Applications
across all art units

Statute-Specific Performance

§101
0.9%
-39.1% vs TC avg
§103
41.3%
+1.3% vs TC avg
§102
17.1%
-22.9% vs TC avg
§112
30.9%
-9.1% vs TC avg
Black line = Tech Center average estimate • Based on career data from 733 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 Preliminary Amendment filed on 05 January 2024 has been entered; claims 1-4 remain pending. 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 3 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. With respect to claim 3, the term “dense” is a relative term which renders the claim indefinite. The term “dense” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. For the purposes of examination, the examiner will consider the limitation “dense layer” as a layer. 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. Claims 1-4 are rejected under 35 U.S.C. 103 as being unpatentable over Nakao et al. (U.S. Patent Publication # 2015/0314245), hereinafter “Nakao”. With respect to claim 1, Nakao teaches a composite separation membrane (Abstract) which is permeable to water and rejects salt (“semipermeable”) (Paragraph [0057]), comprising: a porous support membrane comprising polyvinylpyrrolidone (Paragraph [0080]) and a separation layer comprising a sulfonated polyarylene ether copolymer which includes a hydrophobic segment repeating unit represented by the recited formula (1) and a hydrophilic segment repeating unit represented by the recited formula (2) as copolymerization components (see Paragraphs [0050, 0109]), wherein a sum of the component ratio (in mole) of the formula (1) and the component ratio (in mole) of formula (2) is 1.00 (no other monomers disclosed), wherein R1 and R2 represents -SO3M where M = a metallic element (Paragraphs [0052, 0109, 0110]), wherein repeat segments of formula (2) are present at more than 10% and less than 70% (and there the balance of more than 30% and less than 90% of repeat segments of formula (1)), which encompasses 35 to 50% or 0.35 to 0.50 mole ratio component for formula (2) and 50 to 65% or 0.50 to 0.65 mole ratio component for formula (1). Nakao and the claims differ in that Nakao does not teach the exact same proportions for the mole fraction of each of the hydrophobic and hydrophilic segments as recited in the instant claims; however, one of ordinary skill in the art at the time the invention was made would have considered the invention to have been obvious because the compositional proportions taught by Nakao overlap the instantly claimed proportions for the hydrophobic and hydrophilic segments, and therefore are considered to establish a prima facie case of obviousness. It would have been obvious to one of ordinary skill in the art to select any portion of the disclosed ranges including the instantly claimed ranges from the ranges disclosed in Nakao, particularly in view of the fact that; “The normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages”, In re Peterson, 65 USPQ2d 1379 (CAFC 2003). Regarding the recited ratio of (the polyether sulfone)/(the sulfonated polyarylene ether copolymer)/(the polyvinylpyrrolidone), the Examiner submits that the sulfonated polyarylene ether copolymer is a polyether sulfone. Thus, in order to determine the ratio of (the sulfonated polyarylene ether copolymer)/(the polyvinylpyrrolidone) disclosed by Nakao, it is noted that Nakao teaches that the composite semipermeable membrane comprises a porous support layer comprising polyvinylpyrrolidone at present at preferably greater than 0 to less than 20% of the porous support membrane as a filler (see Paragraph [0080]), while the porous support layer is about 5 to 500 microns thick (Paragraph [0097]) and the separation layer (which contains the sulfonated polyarylene ether copolymer) is about 50 to 500 nm thick (Paragraph [0073]). Taking the example of when the separation layer is 500 nm or 0.5 microns and the porous support layer is 5 microns, the content of the sulfonated polyarylene ether copolymer (which is a polyether sulfone) is 1/10 the amount of the porous support layer which comprises greater than 0 and less than 20% polyvinylpyrrolidone. Taking 1% polyvinylpyrrolidone as the amount in the support layer, the ratio of sulfonated polyarylene ether copolymer to polyvinylpyrrolidone is 1% of 10 or 0.1 to 1 sulfonated polyarylene ether copolymer (which is a polyether sulfone), or 10% of the total, which falls within “3 to 18” recited for polyvinylpyrrolidone, with the balance being sulfonated polyarylene ether copolymer at 90%. The foregoing was simply an example depicting that at least one embodiment disclosed by Nakao overlaps with the recited mass ratio range. The Examiner appreciates that this is a crude estimate based on thickness of the layers; however, it is submitted that the ordinary artisan would have found the recited semipermeable membrane obvious over the teachings of Nakao. Nakao and the claims differ in that Nakao does not teach the exact same proportions for the mass fraction of each of the polymers as recited in the instant claims; however, one of ordinary skill in the art at the time the invention was made would have considered the invention to have been obvious because the compositional proportions taught by Nakao overlap the instantly claimed proportions for the disclosed polymers, and therefore are considered to establish a prima facie case of obviousness. It would have been obvious to one of ordinary skill in the art to select any portion of the disclosed ranges including the instantly claimed ranges from the ranges disclosed in Nakao, particularly in view of the fact that; “The normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages”, In re Peterson, 65 USPQ2d 1379 (CAFC 2003). Additionally, it is submitted that there is no evidence indicating such mass ratios for the polymers are critical. 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. See In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). Regarding the limitations “the semipermeable membrane has cytokine adsorption capabilities suitable for continuous renal replacement therapy”, the Examiner submits that Nakao renders obvious all of the components of the membrane, and therefore the cytokine adsorption capabilities are presumed to be an inherent property of the membrane of Nakao. It has been held that where the Patent Office has reason to believe that a functional limitation asserted to be critical for establishing novelty in the claimed subject matter may, in fact, be an inherent characteristic of the prior art, it possesses the authority to require applicant to prove that the subject matter shown to be in the prior art does not possess the characteristic relied upon. In re Swinehart, 439 F.2d 210, 169 USPQ 226 (CCPA 1971). The Examiner further submits that these limitations pertain to a specific method of using the recited membrane; the membrane of Nakao is capable cytokine adsorption in a continuous renal replacement therapy. With respect to claim 2, the composite membrane of Nakao has a porous support layer that is about 5 to 500 microns thick (Paragraph [0097]) and a separation layer (which contains the sulfonated polyarylene ether copolymer) which is about 50 to 500 nm thick (Paragraph [0073]), therefore, the structure is not uniform in a thickness direction (see also Figs. 3, 4). With respect to claim 3, Nakao teaches that the porous support has large porous (i.e., is less dense) than the separation layer (see Paragraphs [0033, 0067, 0068]; Figs. 3, 4), the placement upon a surface of the support of which can be considered as an “inner surface side thereof”. The Examiner further submits that designating an “inner” (and implied outer) surface of the membrane appears to pertain to the method of using the membrane. With respect to claim 4, regarding the limitations “wherein a NaOH titration amount for the entirety of the semipermeable membrane is from 1.2 to 3.0 mL”, the Examiner submits that Nakao renders obvious all of the components of the membrane, and therefore the NaOH titration amount for the entirety of the semipermeable membrane is presumed to be an inherent property of the membrane of Nakao. It has been held that where the Patent Office has reason to believe that a functional limitation asserted to be critical for establishing novelty in the claimed subject matter may, in fact, be an inherent characteristic of the prior art, it possesses the authority to require applicant to prove that the subject matter shown to be in the prior art does not possess the characteristic relied upon. In re Swinehart, 439 F.2d 210, 169 USPQ 226 (CCPA 1971). The Examiner further submits that these limitations pertain to a specific method of using the recited membrane; the membrane of Nakao is capable of NaOH titration. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to CLARE M PERRIN whose telephone number is (571)270-5952. The examiner can normally be reached 9AM-6PM 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, Bob Ramdhanie can be reached at (571) 270-3240. 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. /CLARE M. PERRIN/ Primary Examiner Art Unit 1779 /CLARE M PERRIN/Primary Examiner, Art Unit 1779 27 February 2026
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Prosecution Timeline

Jan 05, 2024
Application Filed
Feb 27, 2026
Non-Final Rejection — §103, §112 (current)

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Prosecution Projections

1-2
Expected OA Rounds
67%
Grant Probability
99%
With Interview (+42.9%)
2y 11m
Median Time to Grant
Low
PTA Risk
Based on 733 resolved cases by this examiner. Grant probability derived from career allow rate.

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