DETAILED ACTION
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claims 1, 2, 4-7, 9 and 15 are pending as amended on 11/3/2025.
The rejection below has been modified solely to reflect the incorporation of limitations from claim 3 into claim 1. Therefore, this action is properly made final.
Any rejections and/or objections made in the previous Office action and not repeated below are hereby withdrawn. The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office Action.
Claim Rejections - 35 USC § 103
Claim(s) 1, 2, 4-7, 9 and 15 is/are rejected under 35 U.S.C. 103 as being unpatentable over Rafler et al (WO 200906222A1; included machine translation cited herein), with Ouchi et al (US 2008/0097074) cited as an evidentiary reference for claim 7.
As to claims 1, 4, 9 and 15, Rafler discloses L-lactic copolyesters whose properties are controlled mainly by the composition of the monomers used and their comonomer and block length distribution in the polymer. The block copolyesters are prepared by continuous two-step ring-opening polymerization of L,L-lactide with one or more aliphatic heterocycle comonomers (translation p 5, bottom half).
Rafler teaches each of two stages carried out in a separate apparatus. The first stage is carried out in a high mixing intensity reactor to produce uniform block lengths of L-lactide monomers (A blocks). The second stage is carried out in a twin-screw extruder, where comonomers are added to the melt of the poly-L-lactic acid blocks (p 6, upper half). The reactive extrusion system for the synthesis is shown in figure 1 (see translation p 10, top; image copied from original document):
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In the process taught by Rafler and shown in figure 1, the “dosage L,L-dilactide” (5) into “prereactor” (1) corresponds to the presently recited first step of feeding a first L-lactide feed into a first polymerization reactor section. The prereactor (1) corresponds to the first section recited in claim 15, and the line from (5) to (1) corresponds to the first feeding line recited in claim 15.
The “dosage of poly-L-lactide melt” (6) into twin screw extruder (2) corresponds to the presently recited second step of feeding the output of the first polymerization reactor section (i.e., poly-L-lactide) into a second polymerization reactor section [wherein the portion of Rafler’s twin screw extruder downstream of the inlet for (7) corresponds to the presently recited “second polymerization reactor section”]. The line from (6) to (2) corresponds to the feeding line for feeding output of the first reactor section into the second polymerization reactor section, as recited in claim 15.
The introduction of comonomer via “dosage comonomers” inlet (7) corresponds to the presently recited step of feeding a second lactide feed into the second polymerization reaction section between the first polymerization reactor section (i.e., Rafler’s (1)) and the second polymerization reactor section (i.e., the portion of Rafler’s extruder (2) downstream of (7)). The line from (7) to (2) corresponds to the “second lactide feeding line” recited in claim 15.
In Rafler’s example 2 (see p 10, lower half), the comonomer metered in via (7) is entirely (i.e., 100 wt%) meso-lactide, which meets the instant requirement (see instant claims 1 and 9) that the second lactide feed comprises at least 40 wt% D/meso-lactide and at least 30 wt% meso-lactide.
As to the recitation that the feeding of meso-lactide occurs after at least 30% and at most 95% of the total residence time:
Rafler teaches pure lactic acid block copolyesters having a formula wherein both Block A and Block B are ring-opened units of lactide monomers, wherein the molar fraction of A blocks ranges from 1-99%, wherein the number of monomer units in each of the A and B blocks (“m” and “n”) ranges from 5 to 1000, and wherein the number of blocks “p” ranges from 1 to 100. Rafler teaches that the composition of the blocks is controllable by the structure of the comonomers as well as the polymerization technology, and that relationships between material properties and block length are known in the art (p 7, top half). See also p 8, where Rafler discloses monitoring the course of polymerization via monomer conversion and molar masses of samples taken off, and, teaches that the copolymer composition is adjusted by the molar ratio of the starting monomers and the number of monomers in the blocks is controlled by comonomer reactivity and technology of the ring-opening polymerization and extrusion technique.
Rafler discloses that in the first stage, L-lactide is polymerized to form first (A) blocks of poly-L-lactide. Unreacted L-lactide is still present in the second stage when the comonomer which forms the B blocks is metered in. In the second stage, the introduction and polymerization of the comonomer with the poly-L-lactic blocks and unreacted lactide, as well as transesterifications, leads to formation of further block structures. See page 6, top half.
Rafler fails to specifically teach that the feeding of B-block comonomer (e.g., meso-lactide as in Example 2) occurs after any particular percentage of total residence time.
However, considering Rafler’s disclosure, one having ordinary skill in the art would have recognized that as polymerization of L-lactide in the first stage progresses, the degree of conversion increases and the content of unreacted L-lactide in the poly-L-lactic acid A block transferred to the second stage decreases. One having ordinary skill in the art would have further recognized that both reaction temperature and reaction duration have an effect on polymer molecular weight, degree of conversion, and occurrence of transesterification reactions within formed polymer product. Therefore, given Rafler’s recognition that polymer material properties depend on polymer block length, the person having ordinary skill in the art would have been motivated to select appropriate temperatures and durations for each of the first and second stages of Rafler’s disclosed process in order to achieve block lengths, a degree of conversion, and an overall polymer molecular weight corresponding to a desired set of properties tailored for an intended application. Therefore, when preparing a block copolyester comprising A blocks formed from L-lactide and B blocks formed from meso-lactide (such as in Rafler’s example 2), it would have been obvious to the person having ordinary skill in the art to have selected any appropriate temperature and duration for Rafler’s first stage (polymerization of L-lactide) and any appropriate temperature and duration for Rafler’s second stage (feeding and polymerization of meso-lactide with the poly-L-lactic acid and L-lactide produced in the first stage), including durations of the first and second stages which correspond to feeding of the meso-lactide after at most 95% (or at most 90% as recited in claim 4) of the total residence time, and further including durations which correspond to feeding the meso-lactide after at least 30% of the total residence time.
As to claim 2, Applicant has stated on the record (see remarks filed on 8/11/2025, p 10) that there is no difference in inventive merit or technical contribution whether L-lactide or D-lactide is fed to the first reactor, and the distinction between L-lactide and D-lactide does not materially affect the scope or inventive concept of the claims. Given Applicant’s clear admission on the record that a process as claimed wherein the first lactide feed is L-lactide and the second lactide feed is meso-lactide (as in claim 9) is not patentably distinct from a process as claimed wherein the first lactide feed is D-lactide and the second lactide feed is meso-lactide (as encompassed by claim 2), claim 2 is unpatentable over Rafler for the same reasons set forth above with respect to claim 9.
As to claims 5 and 6, Rafler discloses that the stirred reactor in the first stage is charged with L-L lactide (see examples 1 and 2 on p 10). Rafler also discloses that in the first stage “pure poly-L-lactic acid blocks A are produced…” (p 5, second paragraph). Therefore, Rafler discloses a process wherein the first lactide feed is entirely L-lactide (i.e., free of D-lactide, as recited in claim 5, and free of meso-lactide, as recited in claim 6).
As to claim 7, Rafler does not characterize the block copolymer produced as a stereo-block copolymer. Moreover, Rafler exemplifies a copolymer produced from L-lactide and 10 mol% meso-lactide having a melting point of 165 C (example 2, p 10), as well as a copolymer produced from L-lactide and 15 mol% meso-lactide having a melting point of 158 C (example 4, p 11). Considering that Rafler does not disclose formation of stereocomplex crystals, and further considering that stereocomplex crystals are characterized by a higher melting point than those exemplified by Rafler (i.e., between 190-240 C; see, e.g., US 2008/0097074 paragraph [0020]), there is reasonable basis to conclude that Rafler’s block copolymers are not stereo-block copolymers.
Response to Arguments
Applicant's arguments filed 11/3/2025 have been fully considered
Applicant argues (p 6) that the purpose of Rafler differs from the purpose of the present invention, since the present invention seeks to reduce the amount of off-spec PLA produced during a transition, reduce transition time, reduce meso-lactide loss and allow a wider range of PLA melting temperature. However, the claims do not recite any particular purpose or outcome which must be achieved by the recited method, and which would not be achieved by performing the method of Rafler. Therefore, Applicant’s argument that the instant specification describes a purpose/objective which is not taught by Rafler fails to overcome the rejection of record.
Applicant argues (p 6) that there is no teaching in Rafler to modify the residence time after which the second lactide feed is fed in the process. However, this argument is unpersuasive because it fails to address the discussion in paragraphs 22-23 of the action mailed on 9/8/2025, which establishes that one would have been motivated to vary the durations of Rafler’s first and second stages (i.e., by varying the timing of the addition of the second monomer feed to the polylactic acid A block). Further with regard to the presently claimed timing for the addition of a second lactide feed (based on total residence time), Applicant has not provided any evidence or data which establishes unexpected results/criticality associated with the presently claimed range of 30-95%.
Applicant argues (pp 6-7) that Rafler’s examples teach away from the presently claimed range because Rafler shows addition of second lactide after 7.5 minutes with a total residence time of 40 minutes (citing Table 3 of Rafler), corresponding to 18.75% of total residence time. Rafler’s table 3 summarizes monomer feeds in a model system with gradual monomer dosing. It is not clear that the “model system” procedure summarized in Table 3 was carried out in a reactive extrusion system according to Rafler’s figure 1. However, if the polymerization summarized in table 3 is representative of the process carried out in a reactive extrusion system, then the disclosed feeding of lactide comonomer at, e.g., minute 20 would correspond to a second lactide feed which is fed at 50% of the total (40 minute) residence time, which falls within the claimed range of 30-95% of total residence time. Therefore, in the event that the model system example in Rafler’s Table 3 shows the manner in which second lactide feeds are fed to the reactive extrusion process as described in, e.g., Rafler’s Example 2, the model system does not teach away from feeding a second lactide feed within the presently claimed range of 30-95% of total residence time, as alleged by Applicant.
Conclusion
Applicant's amendment necessitated the modified 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 RACHEL KAHN whose telephone number is (571)270-7346. The examiner can normally be reached Monday to Friday, 8-5.
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/RACHEL KAHN/ Primary Examiner, Art Unit 1766
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