Prosecution Insights
Last updated: April 19, 2026
Application No. 18/568,371

COMPOSITIONS OF HFO-1234YF, HFC-152A, AND HFC-32, AND SYSTEMS FOR USING THE COMPOSITIONS

Non-Final OA §103
Filed
Dec 08, 2023
Examiner
ZERPHEY, CHRISTOPHER R
Art Unit
3799
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
The Chemours Company Fc LLC
OA Round
3 (Non-Final)
48%
Grant Probability
Moderate
3-4
OA Rounds
3y 1m
To Grant
67%
With Interview

Examiner Intelligence

Grants 48% of resolved cases
48%
Career Allow Rate
360 granted / 749 resolved
-21.9% vs TC avg
Strong +19% interview lift
Without
With
+19.1%
Interview Lift
resolved cases with interview
Typical timeline
3y 1m
Avg Prosecution
53 currently pending
Career history
802
Total Applications
across all art units

Statute-Specific Performance

§101
0.7%
-39.3% vs TC avg
§103
51.7%
+11.7% vs TC avg
§102
17.9%
-22.1% vs TC avg
§112
23.4%
-16.6% vs TC avg
Black line = Tech Center average estimate • Based on career data from 749 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 . The claim amendment received 11/25/2025 is entered. Claims 2-6, 9-13, 15-18, 23-30, 32-33, 35-41, 44-47, 52-54, and 56-59 are cancelled. Claims 60-64 are new. CLAIM INTERPRETATION The term “expansion device” of claim 43 is not interpreted under §112f as the term is understood in the art to cover a broad class of structures that takes its name from the function performed, i.e. expansion. A term is not required to denote a specific structure of precise physical structure in order to avoid application of 35 U.S.C. §112(f). MPEP 2181(I)(A). 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: 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. Claim(s) 1, 7-8, 14, 19-22, 31, 34, 42-43, and 60-64 is/are rejected under 35 U.S.C. 103 as being unpatentable over Rached (US 10,035,938) in view of Minor et al (US 9,249,347). Regarding claims 1 and 60-64, Rached discloses a composition comprising a refrigerant blend comprising from about 66 to 80 weight percent HFO-1234yf, from about 5 to 8 weight percent HFC- 32, and 14 weight percent HFC-152a (17th example of table 2 which includes 8% of R32, 78% of R1234yf, and 14% of R152a). Rached discloses 14 weight percent HFC-152a but lacks “more than 14 to about 24 weight percent HFC-152a”. Further the example provided by Rached abuts the range of 5-8 weight percent. Minor discloses a refrigerant blend including HFC-152a in a blend of HFO-1234yf and HFC-32 (exemplary embodiment 1 of columns 10-13). Minor states: “1,1-Difluoroethane may also be referred to as HFC-152a or R152a. HFC-152a is commercially available or may be made by methods known in the art such by reaction of vinyl chloride with hydrogen fluoride in the presence of a catalyst. HFC-152a is non-ozone depleting compound with low global warming potential. HFC-152a flammability is classified as 2 or moderate flammability according to ASHRAE Standard 34-2010.” Emphasis added. (column 8, lines 58-65). “Difluoromethane (HFC-32 or R32) is commercially available or may be made by methods known in the art, such as by dechlorofluorination of methylene chloride. HFC-32 is a non-ozone depleting compound with low global warming potential. HFC-32 flammability is classified as 2 L or low flammability according to ASHRAE Standard 34-2010.” Emphasis added. (column 8, lines 52-57). Minor further discloses ranges of HFC-152a from 1-43% (10:54-59) and more specific ranges, such as 1-18%, 5-15%, and 5-20% (examples in “compositions of note” at 11:50 to 12:3). Minor further discloses ranges of HFC-32 from 1-43% (10:48-53) and more specific ranges, such 5-25% (examples in “compositions of note” at 11:50 to 12:3). Minor further discloses “in a narrow range of HFC-152a, of from about 14.5 weight percent to about 15.5 weight percent, the compositions (three-component or more-than-three-component) have cooling capacity within ±25% of many of the existing refrigerants, particularly, R-22, R-404A, R-134a, and R-407C.” (column 23, lines 11-15). It has been held that the optimization of a result-effective variable is obvious. In this instance Minor discloses a range of 1-43% or more specifically 1-18%, 5-15%, 5-20%, and 14.5-15.5%, weight of HFC-152a in a blend with R-1234yf and R-32. Therefor because HFC-152a is recognized as effecting the result of refrigeration performance; the value of 14-24% is not a product of innovation but of ordinary skill and is obvious. Similarly because HFC-32 is recognized as effecting the result of refrigeration performance and flammability; the value of 5-8% is not a product of innovation but of ordinary skill and is obvious. Regarding claim 7, Rached in view of Minor discloses the composition of claim 1, wherein said refrigerant blend consists essentially of: from about 69 to 80 weight percent HFO-1234yf, from about 5 to 8 weight percent HFC 32, and from more than 14 to 24 weight percent HFC- 152a (17th example of table 2 which includes 8% of R32, 78% of R1234yf, and 14% of R152a). As modified by Minor in claim 1, the range of HFC-152a includes more than 14 weight percent and range of HFC-32 includes 5-8%. Regarding claim 8, Rached discloses said refrigerant provides average temperature glide of about 0.1 K to less than about 4 K (17th example of table 2 has an evaporator glide of 2.5), and wherein said refrigerant has a GWP of equal to or less than about 100 (the GWP of a mixture may be calculated from the mass weighted averages of the constituent components, here the GWP of R1234yf is 4, R152a is 124, and R32 is 675; taking the weight percents from example 17 of table 2 multiplied by their respective GWP values yields: (0.78*4) + (0.14*124) + (0.08*675) = 74.48). Regarding claim 14, Rached discloses the composition of claim 1, but lacks at least one additional compound of those claimed. Rached does provide for the addition of lubricants or stabilizers. Rached further discloses that the refrigerant composition replaces R-134a in a refrigerant cycle (4:11-15). In the previous office action on the merits the Examiner took Official Notice that recovery and recycle machines for refrigerant leave at least trace amounts of refrigerant within the system. In his subsequent reply to this office action, the applicant did not traverse Examiner’s assertion of Official Notice with regard to these elements. Therefore the Official Notice statements by the Examiner regarding these elements are now taken as admitted prior art by Applicant. See MPEP §2144.03(C). In the process of replacing R-134a for the composition as provided in claim 1 trace amounts of R-134a will remain in the refrigerant cycle. It would have been obvious to one of ordinary skill in the art to have provided about 0 to 1 percent R-134a within the system as acceptable tolerance of the recovery and replacement process. In other words it is impractical to remove all of the old refrigerant during recovery and recharge. Regarding claims 19-21, Rached discloses the composition of claim 1 and thus implicitly satisfies the material properties of claims 19-21. Regarding claim 22, Rached discloses the composition of claim1, further comprising a lubricant (4:8-11). Regarding claim 31, Rached discloses the composition of claim1 but is silent concerning water, oxygen, or air within the system. In the previous office action on the merits the Examiner took Official Notice that trace components are present within refrigeration cycles such as water, oxygen, or air. In his subsequent reply to this office action, the applicant did not traverse Examiner’s assertion of Official Notice with regard to these elements. Therefore the Official Notice statements by the Examiner regarding these elements are now taken as admitted prior art by Applicant. See MPEP §2144.03(C). It would have been obvious to one of ordinary skill in the art to have allowed said claimed ranges of water, oxygen, and/or air as a practical and tolerable level of undesirable constituents still allowing the system to operate. Regarding claim 34, Rached discloses the composition of claim1, further comprising at least one stabilizer (3:56-64). Regarding claim 42, Rached discloses a refrigerant storage container containing the refrigerant of claim 1, wherein the refrigerant comprises gaseous and liquid phases (the refrigeration system or heat pump itself is regarded as a container as it contains the refrigerant). Regarding claim 43, Rached discloses a system for heating and cooling the passenger compartment of an electric vehicle, comprising an evaporator, compressor, condenser, and expansion device, each operably connected to perform a vapor compression cycle, wherein the system contains the composition of claim 1 (5:60-62). Claim(s) 48-51 is/are rejected under 35 U.S.C. 103 as being unpatentable over Rached (US 10,035,938) in view of Esch (US 9,651,284) and/or Low (US 9,175,202), and in further view of Minor et al (US 9,249,347). Regarding claims 48 and 51, Rached discloses a method for replacing a refrigerant in a heating and cooling system, comprising providing the a refrigerant blend comprising from about 66 to 80 weight percent HFO-1234yf, from about 5 to 8 weight percent HFC- 32, and 14 weight percent HFC-152a (17th example of table 2 which includes 8% of R32, 78% of R1234yf, and 14% of R152a) as a heat transfer fluid (4:11-14), but lacks replacing R1234yf in an electric vehicle. The examiner previously took official notice that R1234yf is a known refrigerant (it has an “R” designation from ASHRAE) the examiner also previously took official notice that electric vehicles include refrigeration cycles. In the reply received 10/3/2025 applicant challenged the official notice. In response, Esch and Low are provided. Esch discloses a refrigerant servicing device for hybrid vehicles (3:11-40) and include cleaning and re-using refrigerant (1:31-56). Low disclososes replacing HFO-1234yf (1:6) with another refrigerant composition in an electric vehicle (5:4-8). It would have been obvious to one of ordinary skill in the art to have replaced R1234yf refrigerant in an electric vehicle with the composition provided by Rached in order to observe the performance benefits, e.g. high COP and low ODP, of the disclosed composition. It is noted that as Esch re-uses the same refrigerant to recharge after recovery that the composition of Rached which includes HFO-1234yf, replaces the HFO-1234yf. Rached discloses 14 weight percent HFC-152a but lacks “more than 14 to about 24 weight percent HFC-152a”. Further the example provided by Rached abuts the range of 5-8 weight percent. Minor discloses a refrigerant blend including HFC-152a in a blend of HFO-1234yf and HFC-32 (exemplary embodiment 1 of columns 10-13). Minor states: “1,1-Difluoroethane may also be referred to as HFC-152a or R152a. HFC-152a is commercially available or may be made by methods known in the art such by reaction of vinyl chloride with hydrogen fluoride in the presence of a catalyst. HFC-152a is non-ozone depleting compound with low global warming potential. HFC-152a flammability is classified as 2 or moderate flammability according to ASHRAE Standard 34-2010.” Emphasis added. (column 8, lines 58-65). “Difluoromethane (HFC-32 or R32) is commercially available or may be made by methods known in the art, such as by dechlorofluorination of methylene chloride. HFC-32 is a non-ozone depleting compound with low global warming potential. HFC-32 flammability is classified as 2 L or low flammability according to ASHRAE Standard 34-2010.” Emphasis added. (column 8, lines 52-57). Minor further discloses ranges of HFC-152a from 1-43% (10:54-59) and more specific ranges, such as 1-18%, 5-15%, and 5-20% (examples in “compositions of note” at 11:50 to 12:3). Minor further discloses ranges of HFC-32 from 1-43% (10:48-53) and more specific ranges, such 5-25% (examples in “compositions of note” at 11:50 to 12:3). Minor further discloses “in a narrow range of HFC-152a, of from about 14.5 weight percent to about 15.5 weight percent, the compositions (three-component or more-than-three-component) have cooling capacity within ±25% of many of the existing refrigerants, particularly, R-22, R-404A, R-134a, and R-407C.” (column 23, lines 11-15). It has been held that the optimization of a result-effective variable is obvious. In this instance Minor discloses a range of 1-43% or more specifically 1-18%, 5-15%, 5-20%, and 14.5-15.5%, weight of HFC-152a in a blend with R-1234yf and R-32. Therefor because HFC-152a is recognized as effecting the result of refrigeration performance; the value of 14-24% is not a product of innovation but of ordinary skill and is obvious. Similarly because HFC-32 is recognized as effecting the result of refrigeration performance and flammability; the value of 5-8% is not a product of innovation but of ordinary skill and is obvious. Regarding claims 49-50, Rached discloses the composition of claim 1 and thus implicitly satisfies the material properties of claims 49-50. Claim(s) 55 is/are rejected under 35 U.S.C. 103 as being unpatentable over Rached (US 10,035,938), Minor et al (US 9,249,347), and in view of Hulse et al (US 11,214,720). Regarding claim 55, Rached discloses a method for reducing the temperature glide in a heat exchanger, the method comprising adding HFC-152a to the refrigerant blend composition, wherein the composition comprises at least about 70 weight percent up to 80 weight percent HFO-1234yf (several examples of table 2 provides for at least 70% R1234yf with R152a and R32). The average temperature glide in the heat exchanger is reduced to less than 4 K,13:36). Hulse further discloses adding R152a as a third component (table 1 at column 16). It would have been obvious to one of ordinary skill in the art to have replaced the composition of only R32 and R1234yf with the composition of R32, R1234yf, and R152a as disclosed at at least table 2 of Rached in order to achieve the desirable cycle characteristics as taught by Rached and Hulse. Rached discloses 14 weight percent HFC-152a but lacks “more than 14 to about 24 weight percent HFC-152a”. Further the example provided by Rached abuts the range of 5-8 weight percent. Minor discloses a refrigerant blend including HFC-152a in a blend of HFO-1234yf and HFC-32 (exemplary embodiment 1 of columns 10-13). Minor states: “1,1-Difluoroethane may also be referred to as HFC-152a or R152a. HFC-152a is commercially available or may be made by methods known in the art such by reaction of vinyl chloride with hydrogen fluoride in the presence of a catalyst. HFC-152a is non-ozone depleting compound with low global warming potential. HFC-152a flammability is classified as 2 or moderate flammability according to ASHRAE Standard 34-2010.” Emphasis added. (column 8, lines 58-65). “Difluoromethane (HFC-32 or R32) is commercially available or may be made by methods known in the art, such as by dechlorofluorination of methylene chloride. HFC-32 is a non-ozone depleting compound with low global warming potential. HFC-32 flammability is classified as 2 L or low flammability according to ASHRAE Standard 34-2010.” Emphasis added. (column 8, lines 52-57). Minor further discloses ranges of HFC-152a from 1-43% (10:54-59) and more specific ranges, such as 1-18%, 5-15%, and 5-20% (examples in “compositions of note” at 11:50 to 12:3). Minor further discloses ranges of HFC-32 from 1-43% (10:48-53) and more specific ranges, such 5-25% (examples in “compositions of note” at 11:50 to 12:3). Minor further discloses “in a narrow range of HFC-152a, of from about 14.5 weight percent to about 15.5 weight percent, the compositions (three-component or more-than-three-component) have cooling capacity within ±25% of many of the existing refrigerants, particularly, R-22, R-404A, R-134a, and R-407C.” (column 23, lines 11-15). It has been held that the optimization of a result-effective variable is obvious. In this instance Minor discloses a range of 1-43% or more specifically 1-18%, 5-15%, 5-20%, and 14.5-15.5%, weight of HFC-152a in a blend with R-1234yf and R-32. Therefor because HFC-152a is recognized as effecting the result of refrigeration performance; the value of 14-24% is not a product of innovation but of ordinary skill and is obvious. Similarly because HFC-32 is recognized as effecting the result of refrigeration performance and flammability; the value of 5-8% is not a product of innovation but of ordinary skill and is obvious. Response to Arguments Applicant's arguments filed 11/25/2025 have been fully considered but they are not persuasive. At page 8 applicant purports that the rejection lacks “citation or rationale”. PNG media_image1.png 137 588 media_image1.png Greyscale While the remarks quote a small sub-portion of a sentence within the rejection statement the immediately previous clause (of the same sentence) not included in the quote states that the rationale is directed to refrigerant performance. Further within the rejection is the discussion from Minor which presents the refrigerant performs with non-ozone depletion and low GWP. At page 8 applicant discusses 134a. The claims make no mention of R-134a other than in a list of alternatives at claim 14. Both Rached and Minor are concerned with COP performance. Applicant cites to table 1 of Minor which does include a column which includes COP relative to R-22 but not R134a. Further one of skill, as suggested by the citation to Rached, may weight COP performance and environmental concerns, e.g. GWP or ozone depletion. Conclusion The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Shimozono et al (US 11,808,499) method for replacing refrigerant. Minor et al (US 11,674,067) refrigerant composition. Yang et al (US 10,899,951) refrigerant composition. Kuroki et al (US 10,072,193) refrigerant filling method. Minor et al (US 9,249,347) refrigerant composition. Rached (US 9,011,711) replacing heat transfer fluid. Low (US 8,926,856) heat transfer composition. Juhasz et al (US 2024/0409797) refrigerant composition. Any inquiry concerning this communication or earlier communications from the examiner should be directed to CHRISTOPHER R ZERPHEY whose telephone number is (571)272-5965. The examiner can normally be reached M-F 7:00-4:00 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, Jianying Atkisson can be reached at 5712707740. 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. /CHRISTOPHER R ZERPHEY/Primary Examiner, Art Unit 3799
Read full office action

Prosecution Timeline

Dec 08, 2023
Application Filed
Jul 17, 2025
Non-Final Rejection — §103
Oct 03, 2025
Response Filed
Oct 15, 2025
Final Rejection — §103
Nov 25, 2025
Request for Continued Examination
Nov 28, 2025
Response after Non-Final Action
Dec 04, 2025
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

3-4
Expected OA Rounds
48%
Grant Probability
67%
With Interview (+19.1%)
3y 1m
Median Time to Grant
High
PTA Risk
Based on 749 resolved cases by this examiner. Grant probability derived from career allow rate.

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