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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicants’ submission filed on 5/29/2026 has been entered.
Status of Claims
The examiner acknowledges the amendment to claim 1 and the addition of claim 22. Claims 1-12 and 14-22 are pending.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-12 and 14-22 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Though applicants' originally filed supporting disclosure, including para [0007, 0014, and 0028], provides support for the employment of polyepoxide and polyhydrazide crosslinkers together and the formation of unique linkages in the cross-linked product through their combined use, it is not seen or made evident that applicants were in possession at time of original filing of the employment of 'reaction products of polyepoxide and polyhydrazide' as crosslinkers in methods and preparations as claimed.
This is a new matter rejection.
Double Patenting
The applicant has amended claim 1. As a result, the previous rejection of double patenting has been withdrawn.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-12 and 14-22 are rejected under 35 U.S.C. 103 as being unpatentable over Minty (US20200095386) and further in view of Yin (CN 103157129).
Regarding Claims 1-2, 12, 18-19, and 22,
Minty teaches a polymeric, water dispersible polymer that causes thickening in aqueous solutions through swelling (Paragraph 5) that is a poly(amino acid) containing carboxylic acid side groups that has been crosslinked (Paragraph 11). Minty also teaches that this crosslink is formed between the side group carboxylic acids (Paragraph 37) and that epoxides may be used for this purpose (Paragraph 37). Minty also teaches that the crosslinker is not limited to those disclosed (Paragraph 37) and can be accomplished using a molecule containing two or more groups reactive with carboxyl groups (Paragraph 37). Minty does not teach the use of a dihydrazide crosslinker group that is added simultaneously with the epoxide-based crosslinker.
Yin teaches the use of adipic acid dihydrazide (Paragraph 20) to crosslink poly(glutamic acid) (Paragraphs 13-16) and uses this to form a hydrogel for biomedical applications in which the hydrogel is used for water absorption (Paragraph 4). One of ordinary skill in the art would look to alternate crosslinking strategies, including the use of multiple types of crosslinker in order to decrease reaction time and to improve resistance to degradation through the use of different reactive chemistries. As both the epoxide containing crosslinker and the dihydrazide crosslinker are used for the purposes of crosslinking the poly(amino acid) composition to generate water absorbing materials, it would have been obvious prior to the effective filing date of the instant application to have combined the two for the purposes of crosslinking the composition. "It is prima facie obvious to combine two compositions each of which is taught by the prior art to be useful for the same purpose, in order to form a third composition to be used for the very same purpose.... [T]he idea of combining them flows logically from their having been individually taught in the prior art." In re Kerkhoven, 626 F.2d 846, 850, 205 USPQ 1069, 1072 (CCPA 1980). See MPEP 2144.06.I. One of ordinary skill in the art, seeking to modify the crosslinking density of the polymer composition would naturally look towards not only the amount but the type of crosslinking compounds to achieve this outcome. It therefore would have been obvious prior to the effective filing date of the instant application to have combined the epoxide-based crosslinkers of Minty with the dihydrazide crosslinkers disclosed by Yin to obtain the predictable result of a poly(amino acid) crosslinked with a dihydrazide and an epoxide for use as a water absorbing polymer with a reasonable expectation of success.
Minty discloses the use of epoxide containing cross-linking groups such as those derived from alkane polyols and poly(alkylene glycols) such as ethylene and diethylene glycol as well as polyepoxides such as those from pentaerythritol and trimethylolethane (Paragraph 38). Yin teaches the use of adipic acid and succinic acid dihydrazides (Paragraph 20).
With regard to the crosslinking agent containing a reaction product of a polyepoxide and polyhydrazide, Minty demonstrates a crosslinking reaction at 150 °C (Paragraph 49), which is identical to the reaction temperature used in the examples of the instant application. As such, should any reaction occur between the polyepoxide and polyhydrazide in the method of the instant application, it would logically follow that such a reaction would also take place in the method as demonstrated by Minty.
Finally, in regard to the amount of carbodiimide used, Yin teaches that the relative molar amounts of polymer:crosslinker:carbodiimide should be 1:0.5-3:0.125-0.7 (Paragraph 16), which would allow for an amount of crosslinker:carbodiimide to be as low as 3:0.125, which would equal 4 molar%, and would fall within the range of the instant claim. One of ordinary skill in the art would recognize that the amount of carbodiimide added would affect the rate of crosslinking reaction and would adjust the amount used to obtain a desired reaction rate. As such, it would have been obvious prior to the effective filing date of the instant application to have used any ratio of crosslinker to carbodiimide to obtain a suitable reaction rate.
Regarding Claim 3,
Minty discloses the use of poly(glutamic acid) (Paragraph 11) which by definition would have a carboxylic acid group pendant from every monomer unit. Additionally, the number of pendent carboxylic acid groups in the polymer would be a function of the feed ratio of monomers in the polymerization reaction (if not all of the monomers have pendent carboxylic acid functionality) and the amount of cross-linking agent added to prepare the final material. These variables would be modified during the course of routine experimentation to obtain the desired properties in the final material, rendering the number of carboxylic acid groups pendent to the polymer a result-effective variable. Thus, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the invention to have set the number of pendent carboxylic acid groups to the range selected. See MPEP 2144.05.II.B.
Regarding Claim 4,
Minty discloses the use of poly(amino acids) having a weight average molecular weight of from about 1000 to about 30,000,000 Daltons is used to make the cross-linked poly(amino acid) particles (Paragraph 11). The range is encompassed by the range of the instant claim.
Regarding Claims 5, 10, and 20-21,
Minty teaches the use of a cross-linked poly(amino acid) rheology modifier to prepare thickened aqueous compositions which are used to form an aqueous dispersion” (Paragraph 13). Thus, if the final cross-linked polymer is water soluble or dispersible due to the carboxylic acid functionality, it would necessarily follow that the precursor that is not a cross-linked polymer containing the same functionality would have the same property.
Regarding Claim 6,
The number of carboxylic acid groups contained in the polymer would be a function of the ratio of initiator to monomer in moles and, in the case of a copolymer, the feed ratio, in moles, of the co-monomers. Minty discloses a poly(amino acid) having a weight average molecular weight of from about 1000 to about 30,000,000 Daltons (Paragraph 11). Using a 30 kDa polymer where glutamic acid is the monomer would afford an average of approximately 232 carboxylic acids per polymer chain, which falls within the range of the instant claim.
Regarding Claims 7-9,
Minty discloses the use of monomers such as aspartic acid, glutamic acid, and y-carboxyglutamate monomer units.” (Paragraph 33). Additionally, Minty discloses cross-linked linear homopolymers or copolymers comprising amino acid monomer units having one or more carboxylic acid side groups.” (Paragraph 33) {see also the claims}.
Regarding Claim 11,
Minty teaches the use of blends of different poly(amino acids) (Paragraph 33).
Regarding Claims 14-15,
Minty describes in Example 1 (Paragraph 49) the use of 4.61 g of polymer to 0.0461 mL of ethylene glycol diglycidyl ether (density=1.19 g/mL) and in Example 6 (Paragraph 58) the use of 2 g of polymer to 0.0236 mL of trimethylolpropane triglycidyl ether (density=1.157 g/mL). These correspond to 1.1 and 1.3 weight% of cross-linking agent respectively and further discloses crosslinking density up to one in every ten monomers, which is 10% (Claim 25). The use of multiple crosslinkers is discussed above in regard to claim 1. As both of the disclosed classes of compound are used for the same purpose of crosslinking the poly(amino acid), it would have been obvious to have used them in any ratio to crosslink the polymer. See MPEP 2144.06.I.
Regarding Claims 16 and 17,
Minty teaches the poly(amino acid) polymers are water absorbent and can be used as rheology modifiers (Paragraph 30).
Response to Arguments
Applicants’ arguments filed 5/29/2026 have been fully considered but they are not persuasive for the following reasons.
On page 7, the applicant states that the office has not put forth a motivation to have combined the crosslinkers of Minty and Yin. The examiner disagrees. As noted in the rejection, the use of polyhydrazide and polyepoxide crosslinkers are both used in the art and as such, it would be obvious to have combined them as noted in MPEP 2144.06.I. While the applicant notes on page 8 that the use of the polyhydrazide alone did not gel, the examiner notes that claim 1 includes no reference to the amount of hydrazide crosslinker and points to Yin disclosing that such crosslinkers do form gels with poly(amino acid) polymers (Paragraph 1).
On page 8, the applicant argues that neither Minty nor Yin teach that the polyepoxide and the polyhydrazide create a reaction product. The examiner does not disagree. However, the examiner notes that while the applicant’s specification is suggestive that such a reaction occurs, the applicant does not present evidence in the specification that would demonstrate this to be the case. As such, this argument would rely on a reaction between the two components to be inherent and that one of ordinary skill in the art would expect such a reaction to take place more rapidly than a reaction between the crosslinking compounds individually and the polymer. The examiner notes that currently there is not evidence in the record to support this assertion and that such evidence is necessary as this reaction product is the crux of the invention of the current claims.
On page 8, the applicant argues the unexpected results obtained by following the method of the instant application. The examiner agrees that the evidence supplied in the declaration by Dr. Minty does indeed present evidence that there is a synergistic effect when using the particular crosslinkers in the declaration. The examiner appreciates the time and effort that the applicant put into conducting these experiments and to provide the declaration. However, while the declaration does indicate unexpected results, these results do not provide the evidence to support that the crosslinking agent “includes a reaction product of the polyepoxide and the polyhydrazide” even though it does indicate a synergistic effect when adding the polyepoxide and polyhydrazide simultaneously.
On page 9, the applicant notes that experiments provided in the declaration indicate an unexpected improvement in absorbency under load (AUL) when adding the polyhydrazide and polyepoxide at once rather than sequentially. The examiner agrees that the data provided do indicate a difference between simultaneous and sequential addition with this particular combination of polyepoxide and polyhydrazide, however this simultaneous addition does not appear to be a limitation of the current claims and also does not clearly indicate that the crosslinking agent “includes the reaction product of the polyepoxide and polyhydrazide”.
Also on page 9, the applicant argues that hydrazides are different from amines. The examiner has amended the rejection, rendering this argument to be moot.
On page 10, the applicant argues the ratio of carbodiimide to crosslinker taught by Yin is higher than what is required in new claim 22. The examiner disagrees as noted in the rejection due to the fact that the ratios disclosed for crosslinker and carbodiimide are linked to the amount of polymer and not directly to one another, allowing for a wider range than that argued by the applicant.
In summation, while the examiner agrees that an unexpected synergy has been observed when including the data provided by Dr. Minty’s declaration, this unexpected synergy does not provide the evidence required to establish that this effect is from a crosslinking agent that “includes the reaction product of the polyepoxide and the polyhydrazide” and that while the specification is suggestive that this may be the case, there is not currently evidence of record that clearly indicates this to be occurring. Further, it is unclear whether this effect is commensurate in scope with the structural variety of epoxide and hydrazide containing compounds listed in claim 12.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ADAM J BERRO whose telephone number is (703)756-1283. The examiner can normally be reached M-F 8:30-5.
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, Heidi Kelley can be reached at 571-270-1831. 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.
/A.J.B./Examiner, Art Unit 1765
/JOHN M COONEY/Primary Examiner, Art Unit 1765
Prosecution Insights