Prosecution Insights
Last updated: April 19, 2026
Application No. 18/356,569

Composition Containing Cellulose Ester Polymer With Enhanced Melt Strength Agent

Non-Final OA §103
Filed
Jul 21, 2023
Examiner
KOLB, KATARZYNA I
Art Unit
1767
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Celanese International Corporation
OA Round
1 (Non-Final)
42%
Grant Probability
Moderate
1-2
OA Rounds
3y 8m
To Grant
58%
With Interview

Examiner Intelligence

Grants 42% of resolved cases
42%
Career Allow Rate
77 granted / 181 resolved
-22.5% vs TC avg
Strong +16% interview lift
Without
With
+16.0%
Interview Lift
resolved cases with interview
Typical timeline
3y 8m
Avg Prosecution
73 currently pending
Career history
254
Total Applications
across all art units

Statute-Specific Performance

§101
0.6%
-39.4% vs TC avg
§103
48.7%
+8.7% vs TC avg
§102
23.7%
-16.3% vs TC avg
§112
14.7%
-25.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 181 resolved cases

Office Action

§103
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 . Claim Interpretation Independent claims as filed on 7/21/2023 recite an additive to the cellulose ester and plasticizer blend. The additive is a salt which is added in the amount sufficient to lower a melt flow rate of the polymer composition by at least 20%. Dependent claims 5-10 further define the salt additive and identify it as crosslinker (claim 5), a metal salt (claim 7) the salt content (claim 6) a salt with multivalent cation (claim 8), while claims 9 and 10 define genus and species of the salt respectively. These salts have a very specific chemical structure, which is unique to them only. Therefore, any property that is associated with the salt additive itself is an inherent property. This is because compounds and their properties are mutually exclusive. Support for examiner’s position can be found in attached articles of Lee where chloride salt is utilized to crosslink cellulose acetate. Consequently the salts listed in claim 10 even if their specific purpose is not explicitly disclosed, will inherently perform the function of lowering melt flow rate of the composition which is attributed to its chemical structure and exclusive properties. Claim Objections Claim 12 is objected to because of the following informalities: Claim 12 depend on clam 1. Claim 1 states that the content of the salt has to be sufficient to lower melt flow rate by at least 20% compared to the identical polymer composition which does not have the salt additive. Claim 12 requires the amount of salt to be sufficient to lower the L* value of the composition. It is not clear if the two amounts are to be the same or different since two different effects are being claimed. The applicants is requested to clarify. Failure to do so may result in changing objection to 112 2nd paragraph rejection without affecting finality of the rejection. Appropriate correction is required. 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. 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. 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 1-11, 13-18 are rejected under 35 U.S.C. 103 as being unpatentable over Ambekar (US 20160326343) in view of Combs (US 2013/0096297). With respect to claims 1, 3, 11 and 13, Ambekar discloses composition comprising densified cellulose ester pellets. The pellets comprise cellulose, plasticizer and an additive (Abstract). Composition comprises 0.1-5 wt.% of additive (claim 12), 5-50 wt.% preferably 10-30 wt.% of plasticizer (claims 1 and 8) wherein the content of cellulose acetate will be the balance. Examples disclose content of cellulose acetate to be above 40%. The additives of Ambekar include active compounds [0035] include salts and acids [0040] and salts [0056]. The salts include potassium carbonate, sodium sulphate [0040] as well as metal salts of alkali metals such as hydroxides, carbonates, citrates, lactates, oxalates, phosphates acetates etc. of magnesium and calcium [0056]. The content of the additive is in a range of 0.1-5 wt.% which encompasses 10,000 ppm (1 wt.%). The cellulose acetate of Ambekar has degree of substitution of less than 3 due to cleaving of sulfate ester groups and replacing them with hydroxyl groups [0023]. Acetylated cellulose is then subject to controlled partial hydrolysis. Although Ambekar teaches controlled partial hydrolysis, he does not disclose the acetyl value of the cellulose acetate utilized in his composition. The US 2013/0096297 to Combs is referred to as reference producing cellulose utilized therein. In other words, Combs is incorporated as a reference by Ambekar [0019]. Specific examples disclose cellulose acetate having acetyl value of 55.4 or less [0052] see also Table 1 [0066]. Combs discloses process of making cellulose acetate flake. The cellulose acetate flake is subject to hydrolysis to alter biodegradability of the cellulose article [0003]. Specifically at higher acetylation the biodegradability is reduced. Combs teaches that the cellulose acetate obtained using his process results in composition having improved mechanical strength, higher viscosity and clarity. Having said that, one of ordinary skill in the art would readily know that modification to polymers resulting in higher viscosity will have lower melt flow rate. This is a fundamental principle in polymer processing due to viscosity of the polymer melt which quantifies how think or thin liquid is. More precisely, how much force is needed to make it move. In the light of the above disclosure, it would have been obvious of one having ordinary skill in the art at the time instant invention was filed to utilize cellulose acetate of Combs in the teachings of Ambekar and thereby obtain instant invention. Ambekar explicitly states that cellulose acetates of Combs are utilized, which is often that in US Patent Practice to avoid lengthy specification. Additionally Combs teaches that biodegradability of cellulose acetates can be tailored by adjusting acetyl values or the degree of hydrolysis. With respect to reducing melt flow rate, as it was mentioned above, increasing acetyl value as it was shown above, Ambekar teaches composition comprising cellulose flake of Combs having claimed acetyl value. Ambekar further utilizes the cellulose of Combs in the same amount as claimed invention. Furthermore, Ambekar discloses salt additive which is taught to be utilized in the amount that overlaps with the claimed amount. The salt of Ambekar is an active component and include acetates and lactates of magnesium or calcium [0056] wherein calcium acetate is utilized in applicant’s examples. Consistent with the claimed interpretation above, calcium acetate has exactly the same chemical structure. In turn the calcium acetate will have exactly the same properties within the same polymer environment (cellulose acetate and the same plasticizer) therefore it will also have the same effect on the composition absent any other data which would suggest otherwise, and the fact that applicants examples only show three components within the composition: cellulose acetate, triacetin as plasticizer and calcium acetate. There is nothing shown in the examples which would attribute lowering of the melt flow index and contradict examiner’s position. Consequently, Ambekar’s composition will meet not only lowering of melt flow rate of claim 1 but also that of claim 3. With respect to claim 2, compounds of Ambekar are salts and by default cation will be part of the polymer composition. With respect to claim 4, a melt flow rate (Index) measured at 210oC using ISO 1133 where the load is 2.16 kg. MFI is less than 20 g/10 minutes. [0085] and Table 2. With respect to claim 5, consistent with the claim interpretation above, calcium acetate or magnesium acetate due to them having exactly the same structure, would inherently crosslink the composition having the same functional group wherein plasticizer is the same and wherein the cellulose acetate has the same acetyl value. With respect to claim 6, the content of active additive is in a range of 0.05-5 wt.%, preferably 0.1-2wt% [0056] encompassing the claimed range. With respect to claims 7-10, metal salts of Ambekar include hydroxides, carbonates, lactates, acetates and the like of alkali metals which include magnesium and calcium [0056]. While Ambekar does not identify these compounds as crosslinkers, as mentioned above compounds and their properties are mutually exclusive. Additionally, a discovery of a new property or use of previously known composition, even if unobvious from prior art, cannot impart patentability to claims of known composition. In re Spada 15 USPQ2d 1655 (CAFC 1990). With respect to claims 14 and 15, Ambekar teaches use of plasticizers. Examples disclose use of triacetin. Other plasticizers such as polyethylene glycol can be found in [0029] With respect to claim 16, as disclosed above, Ambekar utilizes acetates of Combs in his invention. Preferred acetate in Combs is diacetate [0046, 0066]. With respect to claims 17 and 18, densified pellet can be extruded or injection molded into shaped product [0065]. Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Ambekar (US 20160326343) in view of Combs (US 2013/0096297). Ambekar discloses composition comprising densified cellulose ester pellets. The pellets comprise cellulose, plasticizer and an additive (Abstract). Composition comprises 0.1-5 wt.% of additive (claim 12), 5-50 wt.% preferably 10-30 wt.% of plasticizer (claims 1 and 8) wherein the content of cellulose acetate will be the balance. Examples disclose content of cellulose acetate to be above 40%. The additives of Ambekar include active compounds [0035] include salts and acids [0040] and salts [0056]. The salts include potassium carbonate, sodium sulphate [0040] as well as metal salts of alkali metals such as hydroxides, carbonates, citrates, lactates, oxalates, phosphates acetates etc. of magnesium and calcium [0056]. The content of the additive is in a range of 0.1-5 wt.% which encompasses 10,000 ppm (1 wt.%). The cellulose acetate of Ambekar has degree of substitution of less than 3 due to cleaving of sulfate ester groups and replacing them with hydroxyl groups [0023]. Acetylated cellulose is then subject to controlled partial hydrolysis. Although Ambekar teaches controlled partial hydrolysis, he does not disclose the acetyl value of the cellulose acetate utilized in his composition. The US 2013/0096297 to Combs is referred to as reference producing cellulose utilized therein. In other words, Combs is incorporated as a reference by Ambekar [0019]. Specific examples disclose cellulose acetate having acetyl value of 55.4 or less [0052] see also Table 1 [0066]. Combs discloses process of making cellulose acetate flake. The cellulose acetate flake is subject to hydrolysis to alter biodegradability of the cellulose article [0003]. Specifically at higher acetylation the biodegradability is reduced. Combs teaches that the cellulose acetate obtained using his process results in composition having improved mechanical strength, higher viscosity and clarity. Having said that, one of ordinary skill in the art would readily know that modification to polymers resulting in higher viscosity will have lower melt flow rate. This is a fundamental principle in polymer processing due to viscosity of the polymer melt which quantifies how think or thin liquid is. More precisely, how much force is needed to make it move. In the light of the above disclosure, it would have been obvious of one having ordinary skill in the art at the time instant invention was filed to utilize cellulose acetate of Combs in the teachings of Ambekar and thereby obtain instant invention. Ambekar explicitly states that cellulose acetates of Combs are utilized, which is often that in US Patent Practice to avoid lengthy specification. Additionally Combs teaches that biodegradability of cellulose acetates can be tailored by adjusting acetyl values or the degree of hydrolysis. A melt flow rate (Index) of composition of Ambekar is measured at 210oC using ISO 1133 where the load is 2.16 kg. MFI is less than 20 g/10 minutes (see examples). [0085] and Table 2. Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Ambekar (US 20160326343) in view of Combs (US 2013/0096297). Ambekar discloses composition comprising densified cellulose ester pellets. The pellets comprise cellulose, plasticizer and an additive (Abstract). Composition comprises 0.1-5 wt.% of additive (claim 12), 5-50 wt.% preferably 10-30 wt.% of plasticizer (claims 1 and 8) wherein the content of cellulose acetate will be the balance. Examples disclose content of cellulose acetate to be above 40%. The additives of Ambekar include active compounds [0035] include salts and acids [0040] and salts [0056]. The salts include potassium carbonate, sodium sulphate [0040] as well as metal salts of alkali metals such as hydroxides, carbonates, citrates, lactates, oxalates, phosphates acetates etc. of magnesium and calcium [0056]. The content of the additive is in a range of 0.1-5 wt.% which encompasses 10,000 ppm (1 wt.%). With respect to reducing melt flow rate, as it was mentioned above, increasing acetyl value as it was shown above, Ambekar teaches composition comprising cellulose flake of Combs having claimed acetyl value. Ambekar further utilizes the cellulose of Combs in the same amount as claimed invention. Furthermore, Ambekar discloses salt additive which is taught to be utilized in the amount that overlaps with the claimed amount. The salt of Ambekar is an active component and include acetates and lactates of magnesium or calcium [0056] wherein calcium acetate is utilized in applicant’s examples. Consistent with the claimed interpretation above, calcium acetate has exactly the same chemical structure. In turn the calcium acetate will have exactly the same properties within the same polymer environment (cellulose acetate and the same plasticizer) therefore it will also have the same effect on the composition absent any other data which would suggest otherwise, and the fact that applicants examples only show three components within the composition: cellulose acetate, triacetin as plasticizer and calcium acetate. There is nothing shown in the examples which would attribute lowering of the melt flow index and contradict examiner’s position. Claims 12 and 19 are rejected under 35 U.S.C. 103 as being unpatentable over Ambekar (US 2016/0326343) in view of Combs (US 2013/0096297) as applied to claims 1-11 and 13-18 above, and further in view of Shih (WO 2021/150541). Discussion of Ambekar and Combs from paragraph 1 of this office action is incorporated here by reference. In short summary Ambekar discloses composition comprising cellulose acetate with DS of 2.5-3 [0021] wherein Comb provided information about acetyl content in Ambekar’s cellulose acetate. Wherein plasticizers are utilized in amount of 5-50 wt.% [0030]. The exemplified plasticizer is triacetin and polyethylene glycol is also disclosed. Metal salt additives are utilized are reactive additives and are utilized in amount of 0.05-5 wt.% preferably 0.1-2 wt.%. The biodegradability of the cellulose acetate of Ambekar is further elaborated by Combs, as dependent on the content of the acetyl functionality. While Ambekar discloses that the pellets formed are utilized in making shaped objects using extrusion or injection molding, Ambekar does not specify what these injection molded article are and what could be its L* value. In the same field of endeavor, Shih discloses cellulose acetate composition comprising cellulose acetate having DS in a range of 2.2-2.6, which is within the range disclosed by Ambekar [0004]. Plasticizers utilized in examples are triacetin and PEG and their content is within 1-40 wt.% [0019] which is also encompassed by disclosure of Ambekar. Basic additives of Shih include salts [0043] such as magnesium hydroxide, calcium hydroxide as well as bicarbonate version of magnesium and calcium, which meet the limitations of instant claims 5-10. With respect to claim 19, the composition of Shih is utilized to make articles which are melt processed. These articles require specific colors, transparency and other properties including haze [0088]. The articles include cups, straws, plates, bowls, containers, lids, cutlery and the like. In the light of the above disclosure, it would have been obvious to one having ordinary skill in the art at the time instant invention was filed to utilize the composition of Ambekar to make articles of Shih and thereby obtain the claimed invention. Composition of Ambekar in addition to its use in molded articles can be tailored to adjust biodegradability of the composition in order to meet the requirements of the product for which the composition is intended. With respect claim 12 and lowering of the L*, Ambekar does not explicitly teach how such value can be lowered, however, the lowering of it is obvious for following reason. The basic salts of Ambekar as well as those of Shih have the exactly same chemical structure as the basic compound of instant claim 10. These compounds are the only components utilized in a composition comprising the same cellulose acetate and the same plasticizer as those of the instant invention as such only the three components dictate the properties of the composition. Therefore all properties associated with the composition will also be within the same range. Consequently if addition of the same salt crosslinks the composition and lowers its melt flow rate, the L* will be also lowered. Correspondence Any inquiry concerning this communication or earlier communications from the examiner should be directed to KATARZYNA I KOLB whose telephone number is (571)272-1127. The examiner can normally be reached M-F. 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, Mark Eashoo can be reached at 5712701046. 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. /KATARZYNA I KOLB/Primary Examiner, Art Unit 1767 March 4, 2026
Read full office action

Prosecution Timeline

Jul 21, 2023
Application Filed
Mar 04, 2026
Non-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

1-2
Expected OA Rounds
42%
Grant Probability
58%
With Interview (+16.0%)
3y 8m
Median Time to Grant
Low
PTA Risk
Based on 181 resolved cases by this examiner. Grant probability derived from career allow rate.

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