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 .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 11/13/2025 has been entered.
Claims 1, 3-7, 9-18 and 20 are pending as amended on 11/13/2025.
Any rejections and/or objections made in the previous Office action and not repeated below are hereby withdrawn. The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office Action.
Claim Rejections - 35 USC § 112
Claim 10 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.
Claim 10 depends from claim 2. Claim 2 has been cancelled, rendering the scope of claim 10 unclear. For examination purposes, claim 10 has been interpreted as depending from claim 3.
Claim Rejections - 35 USC § 103
Claim(s) 1, 3-7, 9-18 and 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Ono et al (JP 2008031127A; machine translation cited herein) in view of Gong et al (Simple process for separation and recycling of nylon 6 and polyurethane components from waste nylon 6/polyurethane debris, Textile Research Journal 2021, Vol. 91(1–2) 18–27), and further in view of Darcel (“What is the Fractional Distillation Process in Solvent Recovery?” pp 1-3, Posted April 13, 2021; Maratek; https://www.maratek.com/blog/what-is-the-fractional-distillation-process-in-solvent-recovery#:~:text=Fractional%20Distillation%20is%20the%20separation,purchasing%20brand%2Dnew%20virgin%20products. Accessed on April 24, 2026), Simons et al (US 6448395) and Agterberg et al (US 2002/0038022).
As to claims 1, 3, 6, 7, 9-12, 18 and 20, Ono discloses a method for recycling nylon/polyurethane fibers by removing the polyurethane component, and then depolymerizing nylon to recover a lactam (abstract). Ono discloses that the polyurethane can be produced using a polyisocyanate and a polyether (p 5, second paragraph), corresponding to a polyether polyurethane (“PU”) as presently recited. Ono teaches that the nylon is preferably nylon 6 (“PA6”), and preferably a homopolymer (p 4, “Nylon fiber”). Ono discloses that nylon which is decomposed into raw materials can be used for a wide range of applications (p 2, background), and therefore, it would have been obvious to the person having ordinary skill in the art to have carried out the method disclosed by Ono on a large scale (i.e., plant scale) in order to provide an industrially useful quantity of recycled product.
As to instant steps a, b.1 and b.2:
Ono discloses a first step (a) wherein nylon fiber processed with PU is mixed with an organic solvent in order to elute (i.e., dissolve) the PU component into the organic solvent. The fiber is mixed with organic solvent at a temperature of 80-180 C, such that nylon fiber does not melt and decomposition of PU can be suppressed (p 5, second to last paragraph). When mixing organic solvent and fiber, as taught by Ono, it would have been obvious to the person having ordinary skill in the art to have selected any appropriate temperature within Ono’s disclosed range of 80-180 C in order to achieve a desired elution rate of PU, while also suppressing decomposition of PU and melting of PA6, including within the presently claimed range of below 100 C. Case law has established that a prima facie case of obviousness is established where the claimed ranges overlap the ranges disclosed by the prior art. See MPEP 2144.05. The step of dissolving PU in an organic solvent by mixing nylon/PU fiber with organic solvent, as suggested by Ono, meets instant steps a and b.1 recited in claim 1. Ono names several examples of organic solvents (p 5, middle), including dimethylacetamide (as recited in claim 7). Ono further teaches a step (b) of taking the PA6 fiber out from the organic solvent containing the PU by filtration of centrifugal drainage (p 6, paragraph 4), which corresponds to obtaining a stream comprising non-dissolved nylon-6 (fiber) and a stream comprising organic solvent and dissolved polyether polyurethane, as recited in instant step b.2.
As to instant steps b.3 and b.4:
As set forth above, Ono discloses that the heating temperature for dissolving PU in organic solvent is selected in order to easily elute the PU component into the organic solvent, and selected such that decomposition of the PU component can be suppressed (p 5, second to last paragraph). However, Ono fails to teach recovering the PU from the PU-rich stream separated from nylon.
Gong discloses that dealing with the large quantity of waste PA6/PU fabrics has been a global problem for many years (p 18), and discloses a process for separating and recycling PA6 and PU components from waste debris (p 19). Like in Ono, the polyurethane (PU) disclosed by Gong is a polyether PU (abstract).
As shown in Scheme I on p 19, Gong discloses a process which comprises steps similar to those taught by Ono, including providing a material comprising PA6 (i.e., nylon 6) and PU (i.e., polyether polyurethane) (corresponding to instant “a”) (p 19, right column), selectively dissolving PU in organic solvent (p 19, right column), and then filtering/vacuum suctioning to provide a PU solution (i.e., a PU rich stream comprising organic solvent and PU) and PA6 fiber (i.e., a nylon 6 rich steam).
Gong further teaches that the dissolved PU can be separated from solvent through adding water, following which it can be further recycled by vacuum suction (p 19, right column). See also Scheme 1, showing addition of water to the dissolved PU to precipitate PU, and filtering and drying PU. Gong teaches that analysis shows there is only PU left in the organic solvent and it can be successfully recycled through the precipitation method (p 24, lower left).
Considering Gong’s disclosure, when separating nylon 6 and PU for recycling, the person having ordinary skill in the art would have been motivated to recover the PU component as a pure (separated) component in order to reduce production of waste PU and in order to reuse PU as a recycled plastic material. Therefore, after obtaining a solution of PU in organic solvent in the process disclosed by Ono, it would have been obvious to the person having ordinary skill in the art to have performed Gong’s disclosed steps of:
combining water (meeting the presently recited “second solvent”) and the solution of organic solvent and dissolved PU, such that PU precipitates from a mixture organic solvent and water (meeting instant step b.3), and
filtering and drying the PU (corresponding to recovering and discharging precipitated PU, as recited in step b.4),
in order to obtain and discharge a pure PU material (i.e., greater than 85 wt% on dry weight basis) suitable for recycling, and, in order to improve environmental protection by minimizing disposal of Ono’s PU component.
As to steps b.6-b.8:
Ono discloses a step of rinsing off the separated nylon fiber to remove adhered PU and organic solvent used for elution, and teaches water (corresponding to the instant “third solvent”) as a preferable example of a solvent for rinsing (p 6, fifth paragraph), corresponding to charging and washing as recited in instant steps b.6 and b7. Ono further teaches a step of drying so that solvent does not remain as an impurity in the collected lactam (p 6, sixth paragraph), corresponding to obtaining and discharging a nylon 6 rich stream and a mixture comprising organic solvent (i.e., elution solvent) and third solvent (rinsing solvent) as recited in instant steps b.7 and b.8.
As to steps b.5 and b.9-b.10, and as to claims 3, 9 and 10:
As set forth above, modified Ono suggests a process wherein a mixture of water (instant second solvent) and organic elution solvent are obtained after separating precipitated PU therefrom, and wherein a mixture of water (instant third solvent) and organic elution solvent are obtained after rinsing nylon 6 fibers with water. Ono fails to teach recycling or reusing the solvent/water mixtures.
However, it was known in the art to recover solvents utilized in a process in order to recycle and reuse the solvent. For example, Gong teaches that the organic solvent used to dissolve PU can be recovered after precipitation of PU with water (p 23, end of last full paragraph). More generally, Darcel discloses that fractional distillation is a solvent recycling process that can be used for separating complex mixtures for reuse (p 1). It separates a mixture into its component parts when the components have separate boiling points, and can be used to recover solvents, allowing a way to reuse solvents instead of purchasing new virgin products (p 2, top). This drastically reduces hazardous waste produced, resulting in lower need for waste removal, and solvent mixtures that have been previously used are able to be separated and used over and over (p 3).
As evidenced by Darcel, the person having ordinary skill in the art would have been motivated to recover solvents used in an industrial process in order to recycle the solvent instead of buying new solvent, and, in order to minimize hazardous waste production. Additionally, the person having ordinary skill in the art would have recognized fractional distillation as being a conventional and appropriate technique for separating components (such as water and organic solvent) in a solvent mixture. It would have been obvious to the person having ordinary skill in the art, therefore, to have fed (“discharged”) each of the mixtures of solvent and water generated in the process of modified Ono (i.e., the mixture of solvent/water generated during PU precipitation, and, the mixture of solvent/water generated during nylon-6 fiber rinsing) to a distillation apparatus (as recited in instant steps b.5 and b.9), and then distilled and discharged the water and the separated organic solvent (as recited in instant step b.10), in order to reuse the organic solvent and the water in the steps of the process where organic solvent and water were originally employed (i.e., in order to reuse organic solvent in the step of dissolving PU, as recited in instant claim 3, and, in order to reuse water in the steps of precipitating PU and rinsing nylon fibers, as recited in instant claim 9). [As to instant claim 10, Darcel teaches that you can further refine your separated solvents to remove and get rid of any undesirable components (p 2, lower half). It would have been obvious to the person having ordinary skill in the art, therefore, to have carried out a process including a step of separating water and organic solvent via distillation prior to recycling each for their original purpose, as suggested by modified Ono, by further refining the separated organic solvent to remove any undesirable component prior to recycling, as taught by Darcel, including degradation products, in order to minimize build-up of contaminants in the process).
As to the recitation that the second solvent in step b.3) (i.e., the water/aqueous solution used to precipitate PU from the solution in organic solvent) is partly or completely the mixture comprising organic solvent and third solvent obtained in step b.7 (i.e., the water/organic solvent mixture obtained from rinsing nylon-6 with water to remove solvent):
Darcel teaches that in the process of fractional distillation, the solution is recirculated multiple times to make sure it is completely separated (p 2). One having ordinary skill in the art would have been motivated to reduce the number of times a solution is recirculated when process efficiency is prioritized more highly than the purity of the recycled solvent components. When reusing water which has been separated from organic solvent by distillation, the person having ordinary skill in the art would have been motivated to reuse distilled fractions of water having small amounts of organic solvent in order to reduce the time and energy associated with performing the distillation. Therefore, when recycling water recovered by distillation from a solvent mixture in the same steps as it was originally employed (i.e., for the steps of rinsing nylon-6 fibers and precipitating PU) in the process of modified Ono, it would have been obvious to the person having ordinary skill in the art to have utilized fractions of distilled water containing some amount of organic solvent, thereby arriving at a process as presently recited wherein the water used in the PU precipitation step is partly the mixture comprising organic solvent and water that was originally obtained from rinsing nylon-6 fibers with water to remove organic solvent.
As to instant “c.1” and claims 6 and 18:
Ono teaches that it is preferable to remove buttons, chucks, metals, and different resins such as cellulose fibers that are insoluble in organic solvent before recycling (p 5, last paragraph, corresponding to a pre-treatment (cleaning) in a pretreatment section (cleaning section) as recited in claims 6 and 18). Ono also teaches rinsing any PU component which remains adhered to nylon fiber (p 6, paragraph 5). It would have been obvious to the person having ordinary skill in the art, therefore, to have decreased the content of impurities (such as other insoluble solid materials via cleaning, and adhered PU via rinsing) in the nylon fiber resulting from Ono’s elution step in order to improve the purity of the ultimately obtained lactam (see p 6, paragraph 6), including to a content of impurities corresponding to a PA6 rich stream of at least 85 w% (dry weight).
Ono further teaches that the nylon fiber is then depolymerized to recover the lactam (p 6, bottom half), corresponding to the presently recited step of charging the nylon 6 rich stream to depolymerization section C.
As to instant “c.2” and “c.3”:
Ono teaches that the depolymerization temperature is preferably 200 to 350 C (p 7, first paragraph), which falls within the presently claimed range of 180 to 400 C. Ono teaches continuously removing aqueous lactam solution from the reactor (p 7, third to last paragraph) and recovering lactam by distillation to separate it from water (p 7, second to last paragraph), corresponding to the presently recited step of obtaining, discharging and recovering caprolactam comprising stream from depolymerization section C.
As to instant c.4), steps (i) through (iii):
Ono teaches that if high purity lactam is required, it can be distilled according to the purpose or combined with a purification method such as recrystallization (p 7, second to last paragraph). Ono exemplifies a process comprising depolymerization to obtain a 9.2% aqueous caprolactam solution, distilling to separate water from the caprolactam, followed by adding sodium (i.e., alkali metal) hydroxide aqueous solution to the caprolactam, and then performing a distillation to obtain caprolactam having a GC purity of 99.98% (p 8, “result”).
However, Ono fails to teach steps of extraction (according to instant (i)) and back-extraction or solvent swap distillation (according to instant (ii)).
Simons discloses a process for purifying an aqueous caprolactam mixture (abstract), comprising extracting an aqueous caprolactam feed with benzene (an organic solvent, and one of those named in instant claim 12), thereby obtaining an aqueous solution from which caprolactam has been released, and, an organic caprolactam solution (col 3, lines 1-14) (corresponding to instant step (i) of extracting crude caprolactam with organic solvent to obtain an aqueous phase and organic phase, wherein organic phase comprises organic solvent, caprolactam and impurities).
Simons subsequently discloses feeding the organic caprolactam phase to an extraction column for back extraction with water (col 3, lines 14-19), thereby obtaining a solution of caprolactam in water for further processing (col 3, lines 20-22) (corresponding to instant “back extraction” step ii). Simons teaches performing a pre-extraction of the organic solvent/caprolactam mixture using water before the back extraction (col 1, lines 30-31; see also col 5, lines 1-14, step c(ii)), which corresponds to a step wherein the organic phase is washed with water, occurring between instant steps (i) and (ii).
When recovering caprolactam via depolymerization of nylon, the person having ordinary skill in the art would have been motivated to carry out any appropriate known purification procedure or combinations thereof in order to obtain a caprolactam having a sufficiently high degree of purity depending, on the requirements of an intended application. It would have been obvious to the person having ordinary skill in the art, therefore, to have recycled nylon/polyurethane fibers by removing the polyurethane component, depolymerizing nylon to recover a crude aqueous caprolactam solution, and purifying the recovered crude caprolactam using a combination of known purification procedures, as taught by Ono, by performing Simons’ steps of extraction with organic solvent, pre-extraction with water, and back extraction (i.e., extracting, washing and back-extracting steps according to instant steps “c.4(i)” through “c.4(ii)”), and then adding sodium hydroxide and performing distillation (as exemplified by Ono) to obtain a purified caprolactam (corresponding to instant step c.4(iii)).
As to instant c.4, step (iv):
As set forth above, Ono teaches recovering lactam by distillation combined with a purification method such as recrystallization if high purity lactam is required (p 7, second to last paragraph). However, Ono fails to teach that the temperature utilized for crystallization of caprolactam is 10-95 C.
Agterberg discloses a process wherein caprolactam can be purified according to conventional techniques, including a crystallization process [0029]. Agterberg explains how crystallization can be conducted in [0030-36], and teaches that water is preferably present in the melt as freezing point depressor, preferably at a concentration of 1-15 wt% [0036-7]. Agterberg teaches that the temperature in the crystallizer is at most 69 C (the melting point of caprolactam) and most preferably 35-67 C [0039]. Considering Agterberg’s disclosure, it would have been obvious to the person having ordinary skill in the art to have carried out Ono’s crystallization of caprolactam at a temperature of 35-67 C (which falls within the claimed range of 10-95 C) in order to achieve a desired balance between yield and purity of caprolactam crystals (and, to have included 1-15 wt% water in order to depress the freezing point, meeting instant claims 11 and 20).
As to claims 4 and 13-17, modified Ono suggests a method according to claim 1, as set forth above. Ono further teaches a step of drying so that solvent does not remain as an impurity in the collected lactam (p 6, sixth paragraph), corresponding to instant (i). Note that dependent claims 13-17 modify (ii)-(iv) of claim 4, but still encompass process wherein none of (ii)-(iv) are met (due to “and/or” separating each of (ii)-(iv)). Alternatively, Ono exemplifies depolymerization in the presence of phosphoric acid (p 8), meeting (iv) of instant claim 4, as well as dependent claims 15 and 17.
As to claim 5, modified Ono suggests a method according to claim 1, as set forth above. Gong teaches that there is high demand for clothing based on PA6 and PU due to their excellent properties (p 18, left). It would have been obvious to the person having ordinary skill in the art to have reused the PU precipitated and recovered from the process of modified Ono in any high demand industrial application in order to ensure economic viability of the process, including in the production of clothing (textiles).
Response to Arguments
Applicant's arguments filed 11/13/2025 have been fully considered. The rejection has been modified, however, Applicant’s arguments which remain relevant to the current rejection are addressed below.
Applicant argues (p 13) that the cited prior art does not disclose the recycling of solvent mixtures (i.e., the in-process solvent recycling loop). However, Darcel has been newly cited to establish the obviousness of modifying a process to include a solvent recycling loop. Because Applicant’s arguments regarding solvent recycling do not account for the newly cited art, Applicant’s arguments are moot.
Applicant argues (p 14) that it was surprising to obtain polyether polyurethane from a process which includes solvent recycling having a purity that allowed replacing virgin polyether polyurethane. However, Applicant has not provided any evidence or data to support allegations of unexpected results, such as evidence which directly compares the purity of polyether polyurethane obtained from a solvent recycling method to the purity of polyether polyurethane obtained from a method without solvent recycling. It is therefore not possible to conduct analyses as required in MPEP 716.02(a)-(f) to determine whether any differences between the claimed invention and the prior art are unexpected differences.
Applicant argues (p 15) that inventive examples 5 and 6 demonstrate a process that meets high caprolactam purity requirements, while comparative examples 3 and 4 show that purification by distillation and oxidation alone or in combination result in insufficient purity. However, in comparative example 3, the depolymerization step is carried out on nylon-6 which has not been separated from polyurethane; in contrast, the cited prior art discloses removal of polyurethane prior to nylon depolymerization (and, Ono recognizes that lactam purity is lowered when nylon fibers with attached polyurethane are depolymerized, see p 3, second full paragraph). In comparative example 4, caprolactam is purified by treating with permanganate; in contrast, purification of caprolactam using permanganate is not taught by a cited prior art reference. Therefore, for at least the reason that a comparison of instant inventive examples 5 and 6 to comparative examples 3 and 4 do not demonstrate unexpected results in comparison with closest prior art, Applicant’s argument is not sufficient to overcome the prima facie case of obviousness.
Additionally, evidence of nonobviousness must be commensurate in scope with the claims which the evidence is offered to support. See MPEP 716.02(d). The purification procedures described in instant examples 5 and 6 are substantially narrower in scope (e.g., with regard to types and amounts of solvent used in extractions, number of repeated extractions and temperatures/durations used of extractions, distillations and crystallizations). If Applicant wishes to overcome the present rejection by showing unexpected results, Applicant must provide sufficient evidence to show that unexpected results would be obtained for all species encompassed by the present claims. Because Applicant has not provided sufficient evidence to show that unexpected results would be obtained for all species encompassed by the present claims, Applicant has not overcome the present rejection by showing unexpected results.
Applicant argues (p 16) that Simons teaches purification of caprolactam obtained by Beckmann rearrangement, which has a clearly distinguishable impurity profile compared to caprolactam obtained via nylon depolymerization. However, Simons generically discloses that the process is for purifying an aqueous caprolactam mixture. There is nothing in Simons indicating that the purification methods disclosed therein are specific to, or preferred for, removing impurities resulting from Beckmann rearrangement (note that Beckmann rearrangement steps are only recited in claims 24-27 of Simons; there is no description of Beckmann rearrangement in Simons’ general disclosure). Therefore, Applicant has not established that one would not have considered Simons’ disclosure relevant for the general purification of caprolactam (including caprolactam produced via nylon depolymerization).
Conclusion
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/RACHEL KAHN/Primary Examiner, Art Unit 1766
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