Prosecution Insights
Last updated: April 19, 2026
Application No. 18/570,522

METHOD AND SYSTEM FOR PRODUCING LIGNIN

Final Rejection §103
Filed
Dec 14, 2023
Examiner
CALANDRA, ANTHONY J
Art Unit
1748
Tech Center
1700 — Chemical & Materials Engineering
Assignee
VALMET AB
OA Round
2 (Final)
63%
Grant Probability
Moderate
3-4
OA Rounds
3y 0m
To Grant
80%
With Interview

Examiner Intelligence

Grants 63% of resolved cases
63%
Career Allow Rate
638 granted / 1014 resolved
-2.1% vs TC avg
Strong +18% interview lift
Without
With
+17.5%
Interview Lift
resolved cases with interview
Typical timeline
3y 0m
Avg Prosecution
62 currently pending
Career history
1076
Total Applications
across all art units

Statute-Specific Performance

§101
1.1%
-38.9% vs TC avg
§103
39.9%
-0.1% vs TC avg
§102
21.0%
-19.0% vs TC avg
§112
26.7%
-13.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1014 resolved cases

Office Action

§103
Detailed Office Action The communication dated 2/17/2026 and 3/5/2026 have been entered and fully considered. Claim 15 and 26 have been canceled. Claims 14 and 16-19 have been amended. Claims 14and 16-25 are pending with claims 20-25 withdrawn from consideration. 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 . Response to Arguments In light of amendment the 112(b) rejections have been withdrawn In light of amendment the Examiner withdraws the rejections towards MIETTINEN. MIETTINEN teaches a pH of 4.5 to 7 which is above a pH of 1-4. In light of amendment the Examiner withdraws the rejections towards VALKONEN. VALKONEN teaches a pH of much lower than the claimed range of 9-11 during the first stage. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 14, 16, 17, and 19 are rejected under 35 U.S.C. 103 as being unpatentable over U.S. 2015/0322104 TIKKA et al., hereinafter TIKKA. As for claim 14, TIKKA discloses a first precipitation stage where an alkali black liquor is adjusted with a first acid, carbon dioxide to a pH of 7 to 11.5 which encompasses the instant claimed range making a prima facie case of obviousness [0020]. TIKKA discloses after precipitation a filtering stage which separates the precipitated lignin with a filter press [0023]. TIKKA discloses a time of 30-60 minutes which falls within the claimed range [0064]. TIKKA discloses that the precipitated lignin is reslurried to a pH of 1 to 3 which falls within the claimed range [0023]. TIKKA discloses the reslurried lignin is heated to a temperature of 100 to 120 degrees C [0027]. This is slightly outside the claimed range. However, differences in temperature will not typically support non-obviousness absent evidence of unexpected results. Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955) (Claimed process which was performed at a temperature between 40°C and 80°C and an acid concentration between 25% and 70% was held to be prima facie obvious over a reference process which differed from the claims only in that the reference process was performed at a temperature of 100°C and an acid concentration of 10%.); Furthermore, temperature is a result effective variable [P-factor is dependent on temperature and time, par. 0036, the p-factor affects hemicellulose removal and lignin yield par. 0063, 0065]. A higher temperature increases the amount of hemicelluloses that will be hydrolyzed but also increases the amount of lignin that will be hydrolyzed. The amount of heating additionally costs more money. The person of ordinary skill in the art would through routine optimalization decrease the temperature to increase lignin yield (and save energy costs) while decreasing the removal of hemicellulose. The effect of temperature is clearly predictable. PNG media_image1.png 442 746 media_image1.png Greyscale The treated lignin then undergoes a second separation [0025]. As for claim 16, TIKKA discloses the reslurried linin is heated to a temperature of 100 to 120 degrees C [0027]. This is slightly outside the claimed range. However, differences in temperature will not typically support non-obviousness absent evidence of unexpected results. Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955) (Claimed process which was performed at a temperature between 40°C and 80°C and an acid concentration between 25% and 70% was held to be prima facie obvious over a reference process which differed from the claims only in that the reference process was performed at a temperature of 100°C and an acid concentration of 10%.); Furthermore, temperature is a result effective variable [P-factor is dependent on temperature and time [0036, the p-factor affects hemicellulose removal and lignin yield 0063, 0065]. A higher temperature increases the amount of hemicelluloses that will be hydrolyzed but also increases the amount of lignin that will be hydrolyzed. The person of ordinary skill in the art through routine optimize decrease the temperature to increase lignin yield while decreasing the removal of hemicellulose. PNG media_image1.png 442 746 media_image1.png Greyscale As for claim 17, TIKKA discloses heating in the slurry [Figure 4]. As for claim 19, TIKKA discloses cooling by at least 40 degrees C. At the discloses temperature of 100 this would be less than 60 degrees C which overlaps the claimed range. At 95 degrees C which is obvious as per above this would be less than 55 degrees C which overlaps the instant claimed range. Claims 18 is rejected under 35 U.S.C. 103 as being unpatentable over U.S. 2015/0322104 TIKKA et al., hereinafter TIKKA, in view of The Storage of Sulfuric Acid in FRP Composite Tanks by Beetle Plastics, hereinafter BEETLE As for claim 18, TIKKA suggests that dilute sulfuric acid is added into the separated precipitated lignin and then heated as per above. TIKKA fails to disclose the temperature prior to heating. BEETLE discloses that dilute sulfuric acid must be stored at a temperature of 150 degrees F or less (less than 65.6 degrees C). As such when the lignin is reslurried the lignin with dilute sulfuric acid will have a temperature between less than 65.6 degrees C. This range therefore overlaps the instant claimed range making a prima facie case of obviousness. The person of ordinary motivated to have the dilute sulfuric acid at a temperature of less than 65.5 (and therefore the reslurried lignin at said temperature) by BEETLE. Specifically, FRP tanks are the best at storing dilute sulfuric acid at concentrations of 70% and below which can cause corrosion in steel/cast iron tanks. BEETLE gives the allowable max storage temperature of these tanks. Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to ANTHONY J CALANDRA whose telephone number is (571)270-5124. The examiner can normally be reached Monday-Friday 7:45 AM -4:15 PM. 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, Abbas Rashid can be reached at (571)270-7457. 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. ANTHONY J. CALANDRA Primary Examiner Art Unit 1748 /Anthony Calandra/ Primary Examiner, Art Unit 1748
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Prosecution Timeline

Dec 14, 2023
Application Filed
Dec 05, 2025
Non-Final Rejection — §103
Feb 17, 2026
Response Filed
Mar 04, 2026
Examiner Interview (Telephonic)
Mar 16, 2026
Final Rejection — §103 (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

3-4
Expected OA Rounds
63%
Grant Probability
80%
With Interview (+17.5%)
3y 0m
Median Time to Grant
Moderate
PTA Risk
Based on 1014 resolved cases by this examiner. Grant probability derived from career allow rate.

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