DETAILED ACTION
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 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.
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, 7, and 23-24 are rejected under 35 U.S.C. 103 as being unpatentable over Alidedeoglu et al. (US 2017/0198090 A1) in view of Richard et al. (US 10,322,978 B2). Alidedeoglu teaches a process for preparing polybutylene terephthalate (PBT) from purified terephthalic acid (PTA) and 1,4-butanediol (BDO) in the presence of a catalyst. Alidedeoglu teaches that PBT oligomer is prepared from PTA and BDO, that the oligomer is heated until it becomes a homogeneous melt, and that polycondensation is performed at approximately 245–260°C. Alidedeoglu further recognizes that thermal degradation is an undesirable side reaction occurring during thermal processing of PBT and therefore carefully controls processing conditions. See ([0002], [0004], [0015], [0019]–[0030]).
Alidedeoglu therefore teaches:
a polyester comprising repeating units derived from 1,4-butanediol (PBT);
heating the polyester to form a homogeneous melt;
processing temperatures within the claimed range; and
catalyst-containing polyester compositions.
Alidedeoglu does not expressly disclose thermally decomposing the polyester for the purpose of manufacturing 1,3-butadiene, nor does Alidedeoglu disclose that the polyester is polybutylene adipate terephthalate (PBAT).
Richard teaches producing 1,3-butadiene from a 1,4-butanediol feedstock by first esterifying 1,4-butanediol and then pyrolyzing the resulting 1,4-butanediol diester. Richard teaches that pyrolysis is conducted at 500–650°C to produce 1,3-butadiene with high conversion and selectivity. See col. 1, lines 15-25; col. 5, lines 20-25; col. 5, lines 5-20
It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to modify the thermal processing of the BDO-derived polyester of Alidedeoglu by employing Richard's known conversion of BDO-derived intermediates to 1,3-butadiene, because Richard teaches that structural units derived from 1,4-butanediol are suitable precursors for butadiene production. Such modification merely applies a known conversion process to another known BDO-derived polyester feedstock to recover a valuable petrochemical product, representing the predictable use of prior-art elements according to their established functions.
Further, substitution of PBAT for PBT would have been obvious because PBAT and PBT are both condensation polyesters containing repeating units derived from 1,4-butanediol, exhibit similar ester-linkage chemistry, and undergo thermal processing using similar techniques. Selection of one known BDO-derived polyester over another would have amounted to the predictable substitution of one known material for another to obtain expected thermal decomposition behavior.
Claim 2
Alidedeoglu teaches heating the PBT oligomer until it melts and becomes homogeneous prior to further thermal processing.
Claim 3
Alidedeoglu melts the polyester directly without introducing solvent during the melting operation.
Claim 4
Alidedeoglu teaches heating the polyester between approximately 245–260°C, which falls within the claimed melting temperature range.
Claim 7
Alidedeoglu performs melt processing of the polyester without solvent, while Richard performs thermal conversion in a pyrolysis reactor. Performing the thermal decomposition without solvent would have been an obvious design choice because neither reference relies upon solvent for the thermal conversion itself.
Claim 23
Richard expressly teaches a two-stage process comprising:
converting 1,4-butanediol to a 1,4-butanediol diester by esterification; and
subsequently pyrolyzing the diester to produce 1,3-butadiene.
It would have been obvious to employ the same sequential conversion when processing the BDO-derived polyester of Alidedeoglu because Richard demonstrates that staged conversion improves overall butadiene production from BDO-derived intermediates.
Claim 24
Richard teaches carrying out the pyrolysis step at 500–650°C, which satisfies the claimed second thermal decomposition temperature. Selecting the first decomposition temperature to recover BDO-derived intermediates while employing Richard's known higher-temperature pyrolysis represents nothing more than routine optimization of sequential thermal conversion conditions.
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Alidedeoglu in view of Richard, and further in view of Phelps et al. (US 7,732,557 B2).
The processes of Alidedeoglu and Richard are discussed above.
Neither Alidedeoglu nor Richard expressly teaches using a tin catalyst.
Phelps teaches that suitable depolymerization catalysts include organotin compounds, including dialkyltin compounds, dialkyltin oxides, dialkyltin alkoxides, stannoxanes, and spiro tin compounds for polyester depolymerization processes. See col. 10, lines 20-40.
It would have been obvious to employ the organotin depolymerization catalyst taught by Phelps in the combined process of Alidedeoglu and Richard because Phelps teaches that such catalysts are suitable for promoting polyester depolymerization reactions. Selecting one known depolymerization catalyst from a finite number of known alternatives constitutes no more than routine optimization that would have predictably achieved the desired thermal decomposition reaction.
Response to Arguments
Applicant's arguments have been fully considered but are not persuasive. Applicant contends that the cited prior art fails to teach or suggest the claimed method of manufacturing 1,3-butadiene by thermally decomposing polybutylene adipate terephthalate (PBAT). The argument is not persuasive because it attacks the references individually rather than the combined teachings of the references. A determination of obviousness is based on what the combined teachings of the prior art would have suggested to one of ordinary skill in the art at the time of the invention, rather than on whether each reference individually discloses every claimed limitation. Alidedeoglu teaches preparing and thermally processing polybutylene terephthalate (PBT) prepared from purified terephthalic acid (PTA) and 1,4-butanediol (BDO). Alidedeoglu further teaches heating PBT oligomer to form a homogeneous melt at approximately 245–260°C and recognizes that thermal degradation is a known side reaction during thermal processing of PBT. Although Alidedeoglu does not expressly teach producing butadiene, Richard expressly teaches that 1,4-butanediol-derived intermediates are suitable feedstocks for producing 1,3-butadiene and teaches thermally converting 1,4-butanediol diesters to 1,3-butadiene by pyrolysis. One of ordinary skill in the art would have recognized that PBT and PBAT are both well-known condensation polyesters containing repeating units derived from 1,4-butanediol and possessing similar ester-linkage chemistry. In view of Richard's teaching that BDO-derived intermediates are useful precursors for producing butadiene, it would have been obvious to apply Richard's known butadiene-production technique to the thermally processed BDO-derived polyester of Alidedeoglu in order to recover the valuable petrochemical product, representing the predictable use of known materials and known conversion chemistry according to their established functions. Applicant's argument that Alidedeoglu discloses PBT rather than PBAT is likewise unpersuasive. The rejection does not rely on the references teaching identical polymers. Rather, PBT and PBAT are structurally related BDO-derived condensation polyesters, and substitution of one known BDO-derived polyester for another would have been an obvious design choice absent evidence that the claimed selection produces an unexpected result. Applicant has not provided persuasive evidence that thermal decomposition of PBAT produces results that are unexpectedly different from those that would have been expected from other known BDO-derived polyesters. To the extent Applicant argues that none of the references individually teaches every limitation of the claims, such argument is not persuasive because nonobviousness cannot be established by attacking the references individually where the rejection is based upon the combined teachings of multiple references. The proper inquiry is what the references would have suggested collectively to one of ordinary skill in the art. Here, Alidedeoglu provides the BDO-derived polyester and its thermal processing, Richard provides the known conversion of BDO-derived intermediates into butadiene, and Phelps, where applied, provides the use of organotin depolymerization catalysts. The Examiner has articulated a sufficient reason why one of ordinary skill in the art would have combined these teachings with a reasonable expectation of success.
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 TAM M NGUYEN whose telephone number is (571)272-1452. The examiner can normally be reached Mon - Frid.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Prem C Singh can be reached at 571-273-6381. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/TAM M NGUYEN/Primary Examiner, Art Unit 1771
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