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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on June 5, 2026 has been entered.
DETAILED ACTION
Claims 1 – 4, 6 – 7, 9 – 10, and 13 – 16 are pending in this application, wherein claims 1 and 7 are amended, claims 5, 8, 11 – 12, and 17 – 18 are canceled, and claims 13 – 16 are withdrawn.
Claims 1 – 4, 6 – 7, and 9 – 10 are currently examined.
Priority
This application is a national stage application of PCT/EP2020/053426, filed February 11, 2020, which claims benefit of foreign priority document EP19157692.5, filed February 18, 2019. This foreign priority document is not in English.
Should applicant desire to obtain the benefit of foreign priority under 35 U.S.C. 119(a)-(d) prior to declaration of an interference, a certified English translation of the foreign application must be submitted in reply to this action. 37 CFR 41.154(b) and 41.202(e).
Failure to provide a certified translation may result in no benefit being accorded for the non-English application is pertinent only when interference arises.
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Withdrawn Objections
The objection to the abstract in the previous Office Action, dated March 5, 2026, is withdrawn in view of the amended abstract.
Withdrawn Rejections
The rejection of claims 1 – 7, 9 – 10, and 17 – 18 in the previous Office Action, dated March 5, 2026, under 35 U.S.C. 103 as being unpatentable over Rowell et al. in view of Zafeiropoulos et al. and Nelson has been considered and is withdrawn in view of the amended claim 1.
The rejection of claim 8 in the previous Office Action, dated March 5, 2026, under 35 U.S.C. 103 as being unpatentable over Rowell et al. in view of Zafeiropoulos et al. and Nelson as applied to claims 1 – 7, 9 – 10, and 17 – 18 above, and further in view of Eriksen et al. has been considered and is withdrawn in view of the amended claim 1.
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:
i. Determining the scope and contents of the prior art.
ii. Ascertaining the differences between the prior art and the claims at issue.
iii. Resolving the level of ordinary skill in the pertinent art.
iv. Considering objective evidence present in the application indicating obviousness or
nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1 – 4, 6, and 10 are rejected under 35 U.S.C. 103 as being unpatentable over Rowell et al. (EP0213252A1, cited in the PTO-892 on September 17, 2024) in view of Sun (Wood and Fiber Science, 2002, Vol. 34, Issue 2, page 306 – 317, PTO-892), Fahey et al. (US3037902), Carvalho et al. (WO2010117288A1), Eriksen et al. (US9091022B2, cited in the PTO-892 on September 17, 2024), and Zafeiropoulos et al. (Journal of Materials Science, 2003, Vol. 38, page 3903 – 3914, cited in the PTO-892 on March 5, 2026).
Rowell et al. teaches a process that is related to the chemical treatment of lignocellulosic materials by acetylation with acetic anhydride in the absence of any cosolvent or added catalyst (Col. 1, lines 2 – 4). During the process, the partially dried or dry lignocellulosic material is impregnated with liquid acetic anhydride and drained, wherein the acetic anhydride is supplied in a proper amount (Col. 6, lines 21 – 23). The impregnated material is placed in a heated, non-pressurized chamber and kept at a temperature of 110 to 120 ⁰C for a period of time, preferably 2 to 8 hours (Col. 5, lines 3 – 4). Thus, Rowell et al. teach a method of acetylating lignocellulosic materials with acetic anhydride in the absence of a catalyst under standard pressure at a temperature of 110 to 120 ⁰C, which reads on step (i) of claim 1. While heated, a vacuum is applied to remove excess or unconsumed reagent and byproduct acetic acid, or the vapors produced are removed by a gasflow (Col. 4, lines 42 – 50). In example II, the lignocellulosic material (wood sample) is oven-dried to 3% moisture content. The samples are placed in a stainless steel basket and dipped in liquid acetic anhydride for 1 minute. Excess reagent is allowed to drain from the samples for 3 minutes. The acetic anhydride to the lignocellulosic materials ratio is about 1.0 w/w – 1.5 w/w. The samples are placed in a preheated cylinder at 120 ⁰C and maintained for 2 hours at that temperature. The solution obtained by condensing the vapor drawn from the cylinder consists of approximately 55% unreacted acetic anhydride and 45% byproduct acetic acid. The components can be separated by fractional distillation and the acetic acid reconverted to acetic anhydride by reaction with ketene (Col. 9, lines 21 – 32; Col. 10, lines 23 – 24). Thus, the disclosure reads on the limitations “pre-dried” the lignocellulosic fibrous material “by heating” of claim 3. The disclosure also teaches separating or removing excess acetic anhydride from the acetylated lignocellulosic material by draining from stainless steel basket and applying a vacuum to remove residual reagent and byproduct, thereby corresponding to the claimed separation of the acetylated material from excess acetic anhydride of step (ii) and step (iii). Rowell et al. further teach that fractional distillation is applied to separate components, which reads on step (iv) of claim 1. The example explicitly demonstrates the step of separating the acetylated lignocellulosic fibrous material from the excess acetic anhydride before the fractional distillation, which reads on the limitations of claim 10. Moreover, the vapor of acetic anhydride and acetic acid produced during heating can be removed by a gasflow through the reactor or by pulling a vacuum, and the chemicals are recovered by condensation, preferably recovered and up-graded by fractional condensation in a distillation tower (Col. 7, lines 27 – 33). Thus, Rowell et al. teach that acetic anhydride is in vapor form, which corresponds to the limitation of claim 6.
However, Rowell et al. do not explicitly teach the weight ratio of acetic anhydride to lignocellulosic fibrous material is approximately 35:1 to 5:1. Rowell et al. do not teach the obtained acetylated lignocellulosic fibrous material has an acetyl value in a range of from approximately 22% to 45% and a DS in the range of 0.95 to 1.22. Rowell et al. do not explicitly teach eliminating acetic anhydride and acetic acid residues adhered to the filtered acetylated lignocellulosic fibrous material by first treating the material under a reduced pressure of approximately 50 mbar to 60 mbar and subsequently washing the material with water. Rowell et al. do not teach that the lignocellulosic fibrous material is not wood or a fibrous material derived from therefrom, wherein the lignocellulosic fibrous material does not include jute fibers, wherein the lignocellulosic fibrous material is a natural fiber recited in claim 2.
Sun teaches the reaction of acetic anhydride with rice straw fiber without solvent. Sun also teaches that acetylation increases with reaction time or temperature (Abstract). Sun teaches the acetylation of rice straw fiber, wherein a quantity of the straw fiber (10 g) is placed in a 500-mL flat bottom flask. Then 300 mL acetic anhydride is added (page 307, Right Col., para. 3).
Fahey et al. teach that a partial acetylated fibrous product can be produced by reacting cellulose fibers with acetic acid and acetic anhydride under anhydrous conditions, without a catalyst (Col. 1, lines 12 – 18). Fahey et al. further teach forming a slurry of cellulose fiber with acetic acid and acetic anhydride, heating the slurry at about 135 – 280 ⁰C, and that by selection of a suitable combination of temperature of time the fiber may be obtained with any desired acetyl content with the indicated range (Col. 2, lines 6 – 21). Fahey et al. further teach acetylating cellulose to any desired acetyl content up to say about 30% and that higher temperature requires shorter acetylation time and vice versa (Col. 2, lines 33 – 39). Fahey et al. exemplify the acetylation, wherein the product is reported to have an acetyl content of 24.1% (Col. 4, lines 23 – 30).
Carvalho et al. teach a filtration, compression, and vacuum drying process for fibrous brewer’s spent grain in which the material is retained as a filter cake in a membrane filter press and thereafter subjected to vacuum drying (Abstract). Carvalho et al. teach that the associated vacuum circuit reduces the pressure within the filtration chambers, thereby promoting vaporization of retained liquid and providing a driving force for extraction of moisture (page 5, lines 26 – 33). Carvalho et al. teaches heating during vacuum drying at about 60 – 120 ⁰C, preferably about 80 – 90 ⁰C, while operating at reduced pressure of about 15 – 100 mbar absolute, preferably about 15 – 50 mbar (page 12, lines 15 – 26). In example 1, Carvalho et al. specifically subjects the filter cake to an absolute pressure of 50 mbar for 4 hours and obtains a dried cake having about 15% moisture, and further states that vacuum pressures of 10 – 100 mbar for 3 – 5 hours may be used to obtain the desired moisture content (page 15, lines 21 – 34; page 16, lines 1 – 21). Carvalho et al. further teach that the final drying result depends on the duration of the drying step and the vacuum pressure within the filtration chambers (page 17, lines 8 – 10). Thus, Carvalho et al. teaches vacuum-drying conditions that overlap the claimed temperature range of about 80 – 95 ⁰C, pressure range of about 50 – 100 mbar, and duration of about 4 – 12 hours. Carvalho et al. also provide the recognized benefit of using reduced pressure to facilitate removal of retained liquid from the fibrous material.
Eriksen et al. teaches a process and apparatus for the preparation of a modified lignocellulosic material (Abstract). It is believed that washing the product in water would remove the remaining chemicals, which have a bad odor (Col. 11, lines 8 – 11). Thus, Eriksen et al. teach that the product is washed with water to remove remaining chemicals, which reads on step (iii) of claim 1.
Zafeiropoulos et al. perform fiber treatment on six different types of flax fibers (page 3904, Right Col., para. 3). The treatment is acetylation, wherein the acetylation is performed following Rowell’s method. The fibers are first “overdried”, that is until no further loss of weight for 24 h at 105 ⁰C. The fibers are then placed in a stainless steel mesh container and dipped into a beaker containing acetic anhydride for 1 min. Afterwards, the fibers are drained for 3 min and placed in a preheated (120 ⁰C) oven for two hours (page 3904, Right Col., para. 5). Thus, Zafeiropoulos et al. provide support that flax fibers may be acetylated following Rowell’s method, which corresponds to the limitations of step (iv) of claim 1 and claim 2.
It would have been prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the acetylation process of Rowell et al. by employing the filtration and vacuum drying techniques in view of Carvalho et al. and the subsequent water washing treatment in view of Eriksen et al. because Rowell et al. teach acetylating lignocellulosic material with acetic anhydride, separating excess reagent from the treated material, and applying vacuum to remove residual unconsumed acetic anhydride and byproduct acetic acid, Carvalho et al. teach separating liquid from fibrous material by filtration to form a filter cake and thereafter subjecting the filtered fibrous material to reduced pressure, and further teach that reduced pressure promotes vaporization of retained liquid and provides a driving force for extraction of liquid from the fibrous material, and Eriksen et al. further teach washing modified lignocellulosic material with water to remove remaining chemicals. The modification would have been obvious because Carvalho et al. and Eriksen et al. merely apply known separation, vacuum treatment, and washing techniques to fibrous or lignocellulosic materials for the same general purposes already sought by Rowell et al., which is removal of excess and residual treatment chemicals from the treated material. One of ordinary skill in the art would have been motivated to employ the filtration and vacuum treatment techniques of Carvalho et al. in the process of Rowell et al. because Rowell et al. teach separating excess reagent from the treated material and applying vacuum to remove residual unconsumed acetic anhydride and byproduct acetic acid and Carvalho et al. further teach that filtration retains the fibrous solid while separating liquid and that reduced pressure facilitates vaporization and extraction of retained liquid, thereby providing an improved process in removing the excess reagents. One of ordinary skill in the art would have been motivated to subsequently wash the treated material with water in view of Eriksen et al. to further remove residual chemicals remaining after vacuum treatment in order to obtain a more purified product. One of ordinary skill in the art would have had a reasonable expectation of success because Rowell et al. demonstrate that vacuum treatment removes unconsumed acetic anhydride and byproduct acetic acid from treated lignocellulosic material, Carvalho et al. demonstrate successful filtration and vacuum removal of retained liquid from fibrous material, and Eriksen et al. demonstrate successful removal of remaining chemicals from modified lignocellulosic material by water washing. Accordingly, the proposed combination would have involved the application of known processing techniques to similar fibrous materials for the known functions and would have been expected to predictably improve removal of excess and residual treatment chemicals.
Regarding the limitation “weight ratio…approximately 35:1 to 5:1” in step (i) of claim 1, Rowell et al. teach an acetic anhydride to lignocellulosic material ratio of about 1.0 – 1.5 w/w, thereby establishing that the relative amount of acetic anhydride to fibrous material is a known process parameter in lignocellulosic acetylation. Sun further teaches acetylating 10 g of rice straw fiber with 300 mL of acetic anhydride, corresponding to an acetic anhydride to fiber weight ratio of approximately 32.4:1, which falls within the claimed range of approximately 35:1 to 5:1. Accordingly, it would have been obvious to employ a higher known reagent to fiber ratio, as taught by Sun, in the process of Rowell et al. to provide sufficient acetylating reagent and achieve the desired extent of acetylation.
Regarding the limitations “acetyl value” of “22% to 45%” and the DS range of “0.95 to 1.22” in step (i) of claim 1, Fahey et al. teach catalyst-free acetylation of cellulose fibers with acetic acid and acetic anhydride under anhydrous conditions and further teach that, by selecting a suitable combination of reaction temperature and time, partially acetylated cellulose fiber may be obtained with a desired acetyl content up to about 30%. Fahey et al. further exemplify an acetyl content of 24.1%, which falls within the claimed acetyl-value range. Based on the standard stoichiometric relationship between acetyl content and DS, an acetyl content of 24.1% corresponds to a DS of approximately 1.19, which falls within the claimed DS range of 0.95 to 1.22. The DS value is calculated based on the disclosed acetyl content of Fahey et al. It would have been obvious for one of ordinary skill in the art to adjust the catalyst -free liquid phase acetylation conditions of Rowell et al. and Sun in view of Fahey et al. to obtain the desired extent of acetylation. Rowell et al., Sun, and Fahey eta l. all employ liquid phase acetic anhydride treatment of cellulosic or lignocellulosic fibrous material without an added acetylation catalyst. Sun further teaches that the extent of acetylation increases with reaction time and temperature, while Fahey et al. explicitly teach that temperature and time may be selected to obtain a desired acetyl content and that higher temperature requires shorter treatment time and vice versa. Thus, Fahey eta l. provide a known method for increasing and controlling the degree of acetylation in a process technically compatible with the liquid phase treatment of Rowell et al. and Sun. One of ordinary skill would have had a reasonable expectation of success because Fahey et al. demonstrate that catalyst-free liquid phase acetylation can achieve an acetyl content within the claimed range and teach control of acetyl content through known reaction conditions.
Regarding the limitation “filtering” in step (ii) of claim 1, Rowell et al. teach retaining the treated lignocellulosic material in a stainless steel basket and allowing excess acetic anhydride to drain from the retained fibers. Under the broadest reasonable interpretation, this operation corresponds to filtering because the solid fibrous material is retained while the excess liquid reagent is separated therefrom. Carvalho et al. further teach filtration of fibrous material to form a filter cake. Thus, it would have been obvious to employ the known filtration technique of Carvalho et al. to accomplish the same solid liquid separation already performed by Rowell et al.
Regarding the limitation “50 mbar to 60 mbar” in step (iii) of claim 1, Rowell et al. teach applying vacuum to the treated lignocellulosic material to remove residual unconsumed reagent and byproduct acetic acid, but do not specify a vacuum of approximately 50 – 60 mbar. Carvalho et al. teach subjecting filtered fibrous material to an absolute pressure of about 50 mbar and explain that reduced pressure promotes vaporization and provides a driving force for extraction of retained liquid. It therefore would have been obvious to employ the approximately 50 mbar vacuum condition taught by Carvalho et al. in the vacuum removal step of Rowell et al. to facilitate removal of residual acetic anhydride and acetic acid from the filtered fibrous material.
Regarding the limitation of lignocellulosic fibrous material in step (iv) of claim 1 and claim 2, Zafeiropoulos et al. teach acetylating flax fibers following Rowell’s method. Flax is a non-wood and non-jute lignocellulosic fibrous material. Accordingly, it would have been obvious substitute flax with the wood sample in the process of Rowell et al. because Zafeiropoulos et al. explicitly demonstrate that the acetylation treatment of Rowell et al. is applicable to flax fibers.
With respect to claim 4, Carvalho et al. teach vacuum drying fibrous material at temperature of about 60 – 120 ⁰C, preferably about 80 – 90 ⁰C, at reduced pressure of about 15 – 100 mbar, and for drying periods of about 3 – 5 hours, including an example employing 50 mbar for 4 hours. Thus, Carvalho et al. teach drying conditions overlapping the claimed temperature of approximately 80 – 95 ⁰C, pressure of approximately 50 – 100 mbar, and duration of approximately 4 – 12 hours. Since Rowell et al. already teach drying the lignocellulosic material prior to acetylation, it would have been obvious to employ the known vacuum drying conditions taught by Carvalho et al. to accomplish the pre-drying step of Rowell et al.
With respect to claim 9, Nelson teaches an integrated continuous acetylation process in which lignocellulosic material is continuously treated while process streams containing acetic acid formed as byproduct are recovered and recirculated. Accordingly, during operation of Nelson’s continuous process, acetylation of incoming fibrous material occurs concurrently with recovery of acetic acid generated from previously treated material. Rowell et al. further teach separating recovered acetic anhydride and acetic acid by fractional distillation. It therefore would have been obvious to employ the known fractional distillation of Rowell et al. as the recovery technique in Nelson’s continuous recovery system, such that distillative separation of generated acetic acid occurs while the continuous acetylation treatment remains in operation, thereby corresponding to the simultaneous limitation of claim 9.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Rowell et al. (EP0213252A1, cited in the PTO-892 on September 17, 2024) in view of Sun (Wood and Fiber Science, 2002, Vol. 34, Issue 2, page 306 – 317, PTO-892), Fahey et al. (US3037902), Carvalho et al. (WO2010117288A1), Eriksen et al. (US9091022B2, cited in the PTO-892 on September 17, 2024), and Zafeiropoulos et al. (Journal of Materials Science, 2003, Vol. 38, page 3903 – 3914, cited in the PTO-892 on March 5, 2026) as applied to claims 1 – 4, 6, and 10 above, and further in view of Xue et al. (Machine Translation of CN102702143A, PTO-892).
Rowell et al., Sun, Fahey et al., Carvalho et al., Eriksen et al., and Zafeiropoulos et al. teach the limitations discussed above.
However, Rowell et al., Sun, Fahey et al., Carvalho et al., Eriksen et al., and Zafeiropoulos et al. do not teach that the step of distillatively separating the acetic acid is conducted at a reduced pressure of approximately 50 to 60 mbar.
Xue et al. teach a method for preparing 2-acetylfuran from acetic anhydride and furan (page 1, para. 1), which is a process of acetylation of furan (page 2, para. 1). During the acetylation, acetic acid is generated. Xue et al. teach that the preferred method to recover the acetic acid is by vacuum distillation under the conditions of 20 – 100 mbar and 30 – 80 ⁰C. In example 1, the recovery of acetic acid is performed in a three-necked flask equipped with a stirring and a condenser, wherein the recovery is conducted under the vacuum condition of 50 mbar and at a temperature of 44 ± 2 ⁰C (page 3, para. 2). Thus, Xue et al. teach the distillative step for acetic acid under a reduced pressure of 20 – 100 mbar, which corresponds to the limitation of claim 7.
It would have been prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the fractional distillation step of Rowell et al. by conducting the distillative separation of acetic acid under the reduced pressure conditions in view of Xue et la. because Rowell et al. teach recovering acetic acid generated during lignocellulosic acetylation by fractional distillation, but do not specify a distillation pressure of approximately 50 – 60 mbar and Xue et al. teach recovering acetic acid generated during an acetylation reaction by vacuum distillation at about 20 – 100 mbar, a range that encompasses the claimed approximately 50 – 60 mbar, and further exemplify acetic acid recovery at 50 mbar. Thus, Xue et al. provide a known set of vacuum distillation conditions for separating the same acetic acid component produced in an acetylation reaction. One of ordinary skill in the art would have been motivated to employ the reduced pressure distillation conditions of Xue et al. in the recovery step of Rowell et al. because vacuum distillation permits recovery of acetic acid at reduced temperature and therefore provides a predictable approach for carrying out the acetic acid separation. One of ordinary skill in the art would have had a reasonable expectation of success because Xue et al. explicitly demonstrate successful recovery of acetic acid by vacuum distillation within the claimed pressure range. Accordingly, applying the known vacuum distillation conditions of Xue et al. to the fractional distillation step of Rowell et al. would have constituted use of a known technique for its known purpose and would have predictably resulted in distillative separation of acetic acid at approximately 50 – 60 mbar.
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Rowell et al. (EP0213252A1, cited in the PTO-892 on September 17, 2024) in view of Sun (Wood and Fiber Science, 2002, Vol. 34, Issue 2, page 306 – 317, PTO-892), Fahey et al. (US3037902), Carvalho et al. (WO2010117288A1), Eriksen et al. (US9091022B2, cited in the PTO-892 on September 17, 2024), and Zafeiropoulos et al. (Journal of Materials Science, 2003, Vol. 38, page 3903 – 3914, cited in the PTO-892 on March 5, 2026) as applied to claims 1 – 4, 6, and 10 above, and further in view of Brown (US4234718).
Rowell et al., Sun, Fahey et al., Carvalho et al., Eriksen et al., and Zafeiropoulos et al. teach the limitations discussed above.
However, Sun, Fahey et al., Carvalho et al., Eriksen et al., and Zafeiropoulos et al. do not teach the method comprises the step of distillatively separating the acetic acid that is occurring simultaneously with the step of treating the lignocellulosic fibrous material.
Brown teaches an integrated process for preparing cellulose acetate in which acetic anhydride is reacted with cellulose to produce cellulose acetate and co-produce acetic acid (Col. 1, lines 24 – 31). Brown further teaches that continuous operation is preferred and that the same is true for subsequent steps of the process (Col. 2, lines 1 – 5). Brown explicitly states that continuous process for acetylating cellulose are well-known to persons skilled in the art (Col. 8, lines 18 – 23). In one example, Brown teaches that acetylation is carried out continuously (Col. 10, line 66). The dilute acetic acid obtained from hydrolysis and precipitation, together with dilute acetic acid obtained from washing the cellulose acetate, is then continuously dehydrated by azeotropic distillation (Col. 11, lines 20 – 23). Thus, Brown teaches an integrated cellulose acetylation process in which acetylation is carried out continuously and an acetic acid-containing stream is continuously subjected to distillation separation, which corresponds to the limitation of claim 9.
It would have been obvious for one of ordinary skill in the art to modify the acetylation process of Rowell et al. by operating the acetylation and acetic-acid recovery/distillation steps continuously in view of Brown because Rowell et al. already teach that acetic anhydride and acetic acid produced during heating may be removed from the reactor and that the recovered chemicals may be upgraded by fractional condensation in a distillation tower and Brown further teaches an integrated cellulose-acetylation process in which acetylation is carried out continuously and an acetic acid-containing stream is continuously subjected to azeotropic distillation. Thus, Brown supplies the known continuous operation arrangement for acetylation and distillative acetic acid recovery, while Rowell et al. supply the specific recovery and fractional separation of the acetic anhydride/acetic acid stream generated during lignocellulosic acetylation. One of ordinary skill in the art would have been motivated to operate the acetic acid recovery and fractional distillation step of Rowell et al. continuously during the acetylation process because Brown teaches that continuous operation is preferred for integrated process and explicitly demonstrates continuous acetylation together with continuous distillative treatment of an acetic acid-containing stream. Such a modification would permit ongoing recovery and recycle of acetic acid while the acetylation process remains in operation, thereby providing an integrated and efficient processing arrangement. One of ordinary skill in the art would have had a reasonable expectation of success because Rowell et al. already demonstrate that the acetic anhydride/acetic acid stream produced during acetylation may be recovered and separated by fractional distillation, while Brown demonstrates that cellulose acetylation and acetic acid distillation may be carried out as continuous operation in an integrated process. Accordingly, operating the known recovery/distillation step of Rowell et al. concurrently with ongoing acetylation would have been expected to predictably provide simultaneous acetylation and distillative separation of acetic acid as required by claim 9.
Responses to Applicant’s Remarks:
Applicant’s Remarks, filed June 5, 2026, have been fully considered. The present Office Action sets forth new grounds of rejection based on a modified combination of references. Accordingly, to the extent Applicant’s arguments are directed specifically to the prior reliance on Nelson for the claimed acetyl value, DS, or acetic anhydride flow rate, those arguments are moot. The substances of Applicant’s arguments regarding the limitations of the amended claims is addressed below in view of the presently applied references.
Applicant argues that Rowell et al., Zafeiropoulos et al., and Nelson do not teach or suggest obtaining a non-wood, non-jute lignocellulosic fibrous material having an acetyl value of approximately 22 – 45% and a DS of 0.95 – 1.22 under the catalyst-free conditions of amended claim 1. Applicant particularly argues that Zafeiropoulos reports only approximately 10 – 15% weight gain when the acetylation method of Rowell et al. is applied to flax and that Nelson’s broad weight gain disclosure does not establish that the presently claimed acetyl value and DS would be achieved under the claimed conditions. However, the rejection is not persuasive because the present rejection no longer relies upon Nelson to establish the claimed acetyl value and DS. Fahey et al. teach producing partially acetylated cellulose fibers by reacting the fibers with acetic acid and acetic anhydride under anhydrous conditions and without a catalyst, and further teach that, by selection of a suitable combination of temperature and time, a desired acetyl content may be obtained. Fahey et al. explicitly teach acetyl contents up to about 30% and exemplify an acetyl content of 24.1%, which falls within the claimed acetyl value range of approximately 22 – 45%. Based on the standard stoichiometric relationship between acetyl content and degree of substitution, an acetyl content of 24.1% corresponds to a DS of approximately 1.19, which falls within the claimed DS range of 0.95 – 1.22. Sun further teaches catalyst-free liquid phase acetylation of lignocellulosic rice straw fiber and teaches that the extent of acetylation increases with reaction time and temperature. Thus, the present rejection relies upon compatible liquid phase acetylation teachings showing that the degree of acetylation may be increased and controlled by selection of known reaction conditions. Accordingly, the prior art provides both a teaching of achieving and controlling a desired degree of acetylation and an acetylation level corresponding to the presently claimed quantitative ranges. Applicant’s reliance on the lower weight gain reported by Zafeiropoulos et al. does not establish that the claimed acetylation level would have been unobvious. Zafeiropoulos et al. is relied upon primarily to demonstrate that the acetylation of Rowell et al. is applicable to flax.
Applicant argues that Nelson’s disclosure of an acetic anhydride flow rate in a continuous vapor process is not equivalent to the claimed acetic anhydride-to-fibrous-material weight ratio and therefore does not teach the claimed approximately 35:1 to 5:1 ratio. However, the argument is moot because the present rejection relies upon Sun to provide such teaching. Rowell et al. teach acetic anhydride-to-lignocellulosic material ratios of about 1.0 – 1.5 w/w, thereby demonstrating that the relative amount of acetic anhydride to lignocellulosic material is a recognized process parameter. Sun further teaches acetylating 10 g of rice straw fiber with 300 mL of acetic anhydride. Based on the density of acetic anhydride to be approximately 1.08 g/mL, Sun’s disclosure corresponds to an acetic anhydride to fiber weight ratio of approximately 32.4:1, which falls within the claimed approximately 35:1 to 5:1 range. Thus, the present rejection directly relies upon a disclosed lignocellulosic fiber acetylation condition within the claimed weight ratio range rather than the flow rate disclosure of Nelson.
Applicant argues that the prior combination does not teach or suggest the claimed purification sequence of separating the acetylated fibrous material from excess acetic anhydride by filtering, treating the filtered material at approximately 50 – 60 mbar to eliminate adhered acetic anhydride and acetic acid residues, and subsequently washing the material with water. Applicant further argues that Eriksen et al. teach only water washing and does not supply the claimed filtration/reduced pressure sequence. However, the argument is moot in view of the presently applied combination. Rowell et al. teach retaining the treated lignocellulosic material in a stainless steel basket, allowing excess acetic anhydride to drain from the retained fibers, and thereafter applying vacuum to remove residual unconsumed reagent and byproduct acetic acid. Under the broadest reasonable interpretation, the basket and drain operation of Rowell et al. corresponds to a solid-liquid separation in which the fibrous solid is retained while excess liquid is removed. Carvalho et al. further teach filtration of fibrous material to form a filter cake and thereafter subjecting the filtered fibrous material to vacuum treatment, including an example at an absolute pressure of 50 mbar. Carvalho et al. also teach that reduced pressure promotes vaporization and provides a driving force for extraction of retained liquid. Thus, the combination of Rowell et al. and Carvalho et al. teaches the claimed filtration technique and a vacuum pressure within the claimed range. Eriksen et al. further teach subsequently washing modified lignocellulosic material with water to remove remaining chemicals. Accordingly, it would have been obvious to employ the filtration with approximately 50 mbar of Carvalho et al. in the vacuum treatment technique in the process of Rowell et al. to facilitate removal of excess and residual treatment liquid from the fibrous material, followed by the water wash taught by Eriksen et al. to remove remaining chemicals. The references therefore provide an articulated reason for the claimed sequence rather than merely isolated disclosures reconstructed without a reason to combine.
Applicant argues that Rowell et al. do not teach the presently claimed non-wood, non-jute lignocellulosic fibrous material and that application of the method of Rowell et al. to flax, as reported by Zafeiropoulos et al., does not produce the claimed quantitative acetylation level. However, the argument is not persuasive. Zafeiropoulos et al. explicitly teach applying the acetylation method of Rowell et al. to flax fibers, thereby demonstrating that the acetylation process of Rowell et al. is applicable to a non-wood, non-jute lignocellulosic fibrous material. Zafeiropoulos et al. is relied upon for the suitability of flax and the reasonable expectation that the acetylation chemistry of Rowell et al. is successfully applied to flax. Fahey et al., rather than Zafeiropoulos et al., is relied upon for the teaching that catalyst free liquid phase acetylation conditions may be selected to obtain acetyl content within the presently claimed range. The cited references need not individually disclose all limitations where the combination as a whole would have rendered the claimed subject matter obvious.
Applicant argues that none of the references teaches the claimed combination of catalyst-free treatment, temperature, pressure, reagent-to-fiber ratio, acetyl value, and DS, and that the Office is improperly reconstructing the claimed process form isolated disclosures. However, the argument is not persuasive because obviousness does not require a single reference to disclose the claimed combination. Rowell et al. supply the catalyst-free acetic anhydride acetylation process under the claimed reaction temperature and pressure conditions; Sun supplies a known acetic anhydride to fiber ratio within the claimed range and further teaches that the extent of acetylation increases with reaction time and temperature; Fahey et al. teach catalyst free liquid phase acetylation of cellulose and explicitly demonstrate an acetyl content within the claimed range while teaching that temperature and reaction time may be selected to obtain a desired acetyl content; Zafeiropoulos et al. demonstrate application of the process of Rowell et al. to flax; Carvalho et al. supply filtration and the claimed reduced pressure treatment of filter fibrous material; and Eriksen et al. supply the subsequent water wash. As set forth in the rejection, the references also provide reasons to make the respective modifications and a reasonable expectation that the modifications would successfully perform the known functions. Accordingly, the rejection is based on the combined teachings of the prior art and not on the premise that Rowell et al. alone must disclose the entire amended process.
Conclusion
No claim is found to be allowable.
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/H.Y.L./Examiner, Art Unit 1693
/ANDREA OLSON/Primary Examiner, Art Unit 1693
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