Prosecution Insights
Last updated: April 19, 2026
Application No. 18/012,465

PROCESS FOR PREPARING POLYIMIDES

Non-Final OA §103§112
Filed
Dec 22, 2022
Examiner
KAHN, RACHEL
Art Unit
1766
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Technische Universität Wien
OA Round
1 (Non-Final)
28%
Grant Probability
At Risk
1-2
OA Rounds
3y 9m
To Grant
44%
With Interview

Examiner Intelligence

Grants only 28% of cases
28%
Career Allow Rate
179 granted / 649 resolved
-37.4% vs TC avg
Strong +16% interview lift
Without
With
+15.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 9m
Avg Prosecution
65 currently pending
Career history
714
Total Applications
across all art units

Statute-Specific Performance

§101
0.2%
-39.8% vs TC avg
§103
48.5%
+8.5% vs TC avg
§102
15.5%
-24.5% vs TC avg
§112
23.7%
-16.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 649 resolved cases

Office Action

§103 §112
DETAILED ACTION The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claims 1-10 are pending as amended on 12/22/2022. Election/Restrictions Applicant's election with traverse of Group II (claims 3 and 4) in the reply filed on 1/12/2026 is acknowledged. The traversal is on the ground(s) that Echigo describes preparation of only one salt, which is a water-soluble salt by chance, and that the other salts disclosed by Echigo would not have been water soluble if tested. However, the fact that Echigo’s broader disclosure includes teachings of salts which are not within the scope of the present claims does not establish the non-obviousness of any salt suggested by Echigo which is encompassed by the present claims. Alternatively, lack of unity is established as set forth in the rejection over Yamashita and Jeol below, which shows that the common technical feature among the groups (a salt according to formula (I) in claim 1) was known in the art. The requirement is still deemed proper and is therefore made FINAL. Claims 1, 2 and 5-10 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Applicant’s election without traverse of species wherein the salt of formula (I) is norbornane bis(methylammonium)-dihydrogentetrahydrofuran carboxylate (15) in the reply filed on 1/12/2026 is acknowledged. The examiner is unaware of prior art which discloses or suggests a process as recited in claim 3 wherein the salt of formula (I) is norbornane bis(methylammonium)-dihydrogentetrahydrofuran carboxylate (15). However, examination has been continued for other species encompassed by claim 3. As set forth in the rejection below, other species which fall within the scope of claim 3 were known in the art, and therefore, no claims are presently free of prior art. 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. Claims 3 and 4 are 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. The last lines of claim 3 recite that “optionally an aliphatic diamine… is added; or an alicyclic diamine…is added.” This recitation is confusing given that several of the salts of formula (I) (as recited in claim 1) are formed from aliphatic diamines having a chain length of 4 to 9 carbon atoms (and therefore for these salts, the additional of such diamines must not be optional). Additionally, claim 3 requires the formation of a specific stoichiometric salt which is a salt of one specific tetracarboxylic acid and one specific diamine, as set forth in “ii)” of claim 1. It is not clear how an optional diamine could be added in addition to the specific diamine required to obtain the recited salt, given that none of the recited salts contain a combination of two or more diamines. Claim 4 is indefinite for the same reasons set forth above for claim 3, and is further indefinite because it recites a preferred embodiment. A broad range or limitation together with a narrow range or limitation that falls within the broad range or limitation (in the same claim) may be considered indefinite if the resulting claim does not clearly set forth the metes and bounds of the patent protection desired. See MPEP § 2173.05(c). In the present instance, claim 4 recites the broad recitation “protic polar solvent,” and the claim also recites “preferably isopropanol,” which is the narrower statement of the range/limitation. The claim is considered indefinite because there is a question or doubt as to whether the feature introduced by such narrower language is (a) merely exemplary of the remainder of the claim, and therefore not required, or (b) a required feature of the claim. 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. Claim(s) 3 and 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Yamashita et al (US 2002/0188090) in view of Jeol et al (US 2014/0228513). As to claims 3 and 4, Yamashita discloses an isomer mixture of norbornane bis(methylamine) (NBDA) PNG media_image1.png 91 235 media_image1.png Greyscale which produces a polyimide having improved and controlled thermal resistance, melt flowability, optical properties, chemical resistance, electrical properties and film properties [0018, 0129, 0163]. NBDA corresponds to the diamine component in presently recited salts 19, 21, 23, 25, and 27 (see claim 1 for salt chemical names). Yamashita discloses a process comprising reacting a mixture of NBDA with a dianhydride [0090, 0327]. Yamashita teaches that the dianhydride may be any aromatic or aliphatic tetracarboxylic dianhydride [0328], and names 1,2,3,4-butanetetracarboxylic dianhydride [0346], 1,2,3,4-cyclobutanetetracarboxylic dianhydride [0348], 1,2,3,4-cyclopentanetetracarboxylic dianhydride [0349], 1,2,4,5-cyclohexanetetracarboxylic dianhydride [0350] and 3,3’,4,4’-benzophenonetetracarboxylic dianhydride [0332] as examples thereof. The person having ordinary skill in the art would have recognized that the final properties of a polyimide depend on the chemical structure thereof. Therefore, when producing Yamashita’s polyimide by reaction of NBDA with dianhydride, one would have been motivated to select any appropriate dianhydride monomer named by Yamashita in order to tailor polyimide properties according to the demands of an intended application. It would have been obvious to the person having ordinary skill in the art, therefore, to have formed a polyimide according to Yamashita by reacting Yamashita’s NBDA isomer mixture with any dianhydride named by Yamashita, including 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride or 3,3’,4,4’-benzophenonetetracarboxylic dianhydride (i.e., dianhydrides having structures corresponding to the tetracarboxylic components in presently recited salts 19, 21, 23, 25, and 27, respectively). Yamashita discloses several types of processes for reaction of diamine and dianhydride, including wherein a diamine and a tetracarboxylic acid are reacted to form a salt monomer, and the monomer is then isolated and polymerized in the absence of a solvent [0406]. However, Yamashita does not provide further details regarding the synthesis and isolation of salt monomer, and therefore fails to teach a salt synthesis utilizing an organic solvent that dissolves both reactants (dianhydride and diamine) but is a non-solvent for the produced salt. Like Yamashita, Jeol discloses a polyimide produced by solid-state polymerization of a solid ammonium-carboxylate salt [0001]. Jeol teaches that the salt may be synthesized in various ways known to those skilled in the art [0050], such as by dissolving tetracarboxylic acid in a solvent such as ethanol or methanol, dissolving a diamine in the solvent, and then mixing and stirring the two solutions, such that the salt formed is insoluble and precipitates out to be recovered (isolated) [0051]. When forming a salt monomer from a diamine and a tetracarboxylic acid as taught by Yamashita, the person having ordinary skill in the art would have been motivated to utilize a synthesis previously developed and known in the art for the production and isolation a salt monomer from the types of monomers taught by Yamashita (tetracarboxylic acid and diamine), in order to efficiently achieve Yamashita’s stated objective of forming and isolating a salt monomer. It would have been obvious to the person having ordinary skill in the art, therefore, to have reacted diamine and tetracarboxylic acid to form and isolate a salt monomer, as taught by Yamashita, by dissolving the tetracarboxylic acid in methanol or ethanol (i.e., polar protic organic solvents), followed by adding a solution of diamine dissolved in the methanol or ethanol, and then mixing and stirring to form a salt which is insoluble and precipitates out to be recovered/isolated, as taught by Jeol. As to the recitation of a “stoichiometric salt,” Yamashita discloses that the polyimide molecular terminals may be blocked or not [0362], and teaches that the molar ratio of all the diamine compound to all the dianhydride is controlled to control the molecular weight of the polyimide prepared, and must be in the range of 0.9 to 1.1 [0378]. Yamashita’s range encompasses an equimolar (1:1) ratio. It would have been obvious to the person having ordinary skill in the art, therefore, to have prepared a non-blocked polyimide from NBDA and dianhydride, as suggested by modified Yamashita, utilizing any ratio of diamine (NBDA) to dianhydride within Yamashita’s disclosed range in order to ultimately achieve a desired polyimide molecular weight, including a 1:1 (stoichiometric) ratio of diamine to dianhydride. As to the recitation that the salt of formula (I) is water-soluble, Yamashita and Jeol are silent as to the water solubility of the suggested solid ammonium-carboxylate salts formed from NBDA and 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride or 3,3’,4,4’-benzophenonetetracarboxylic dianhydride (i.e., salts according to instant salts 19, 21, 23, 25, and 27). However, the water solubility of a compound depends on the chemical structure thereof, and modified Yamashita suggests salts which have the same chemical structure as salts 19, 21, 23, 25, and 27, which are characterized by the instant specification as being water soluble. Since the prior art salts and instant salts are the same, the salts must have the same solubility in water. There is reasonable basis to conclude, therefore, that modified Yamashita suggests salts which are water-soluble as presently recited. Citation of Pertinent Prior Art The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Unterlass et al (WO 2018/032023; English language equivalent US 20190177483 cited herein) discloses an aqueous solution of a water-soluble stoichiometric salt of polycarboxylic acid and polyamine [0012]. Unterlass teaches preparing a salt by mixing stoichiometric amounts of a polycarboxylic acid or its polyanhydride and polyamine in an aqueous solvent mixture, and teaches salts formed from tetrahydrofurantetracarboxylic dianhydride and a diamine which is benzenedimethanamine or ethylenediamine [0019]. Unterlass fails to teach NBDA as a diamine, and therefore fails to teach a salt according to instant elected species (15). Additionally, Unterlass discloses forming a salt by mixing the polycarboxylic acid and diamine in water or an aqueous solvent mixture, and then adding an organic solvent to precipitate the salt [0016]. Therefore, Unterlass fails to teach a method according to instant claim 3 which requires dissolving the carboxylic component in organic solvent which is a non-solvent for the salt prior to addition of diamine, such that the salt precipitates as a result of mixing diamine and carboxylic component in the organic solvent which is a non-solvent for the salt. Echigo (JP 2000319389, cited in the restriction requirement mailed on 8/11/2025) teaches a method for forming a salt of tetracarboxylic acid and diamine, wherein the method specifically requires forming a suspension of tetracarboxylic acid in water and adding diamine thereto, such that the salt dissolves as it forms to become a homogeneous solution (translation p 4). In Echigo’s method, the dianhydride is suspended in a solvent for the salt prior to addition of diamine, and, the salt product remains dissolved as it forms. This differs from the presently claimed method which requires dissolving dianhydride in a non-solvent for the salt prior to addition of diamine, and, requires the salt product to precipitate as it forms. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to RACHEL KAHN whose telephone number is (571)270-7346. The examiner can normally be reached Monday to Friday, 8-5. 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, Randy Gulakowski can be reached at 571-272-1302. 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. /RACHEL KAHN/ Primary Examiner, Art Unit 1766
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Prosecution Timeline

Dec 22, 2022
Application Filed
Dec 22, 2022
Response after Non-Final Action
Feb 18, 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
28%
Grant Probability
44%
With Interview (+15.9%)
3y 9m
Median Time to Grant
Low
PTA Risk
Based on 649 resolved cases by this examiner. Grant probability derived from career allow rate.

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