Ex Parte Meerdink et al

Board of Patent Appeals and Interferences

Aug 1, 2011

10582280 (B.P.A.I. Aug. 1, 2011)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
10/582,280 02/20/2008 Johannes Meerdink 2144.000800/RFE 2928
23720 7590 08/01/2011
WILLIAMS, MORGAN & AMERSON
10333 RICHMOND, SUITE 1100
HOUSTON, TX 77042
EXAMINER
COVINGTON, RAYMOND K
ART UNIT PAPER NUMBER
1622
MAIL DATE DELIVERY MODE
08/01/2011 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte JOHANNES MEERDINK and
NILS DAN ANDERS SADERGARD
__________

Appeal 2011-003179
Application 10/582,280
Technology Center 1600
__________

Before DEMETRA J. MILLS, FRANCISCO C. PRATS, and
JEFFREY N. FREDMAN, Administrative Patent Judges.

FREDMAN, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 involving claims to a process
for purification of lactide. The Examiner rejected the claims as obvious.
We have jurisdiction under 35 U.S.C. § 6(b). We reverse.

Appeal 2011-003179
Application 10/582,280

2
Statement of the Case
Background
“This invention relates to an improved process for the purification of
lactide from a crude lactide vapour product stream comprising at least said
lactide, lactic acid, water and linear lactic acid oligomers” (Spec. 1, ll. 5-8).
The Claims
Claims 1-21 are on appeal. Claim 1 is representative and reads as
follows:
1. A process for the purification of lactide from
a crude lactide vapour product stream comprising
at least said lactide, lactic acid, water and linear
lactic acid oligomers, said crude lactide vapour
product stream being produced by
depolymerisation of low molecular weight
polylactic acid in a reactor, which process
comprises the steps of:
(a) feeding said vapour product stream to a
rectification column having a feed inlet at the
lower end of the column and an overhead vapour
outlet at the upper end of the column, through the
said feed inlet, said column being mounted onto
the reactor such that components from the vapour
product stream liquefying within the column are
allowed to flow back into the reactor;
(b) establishing at the upper end of the
column a first overhead vapour fraction consisting
essentially of water, lactic acid and lactide, and at
the lower end of the column a high-boiling fraction
consisting essentially of lactide and higher-boiling
linear lactic acid oligomers;
(c) condensing from said first overhead
vapour fraction by means of a condenser at least
the lactide to obtain a first liquid lactide containing
condensate fraction;
Appeal 2011-003179
Application 10/582,280

3
(d) removing the first liquid lactide containing
condensate fraction.

The issue
The Examiner rejected claims 1-21 under 35 U.S.C. § 103(a) as
obvious over O’Brien
1
and Drysdale
2
(Ans. 3-4).
The Examiner finds that “O’Brien et al and Drysdale et al teach a
process for the purification of lactide by condensing the vaporous reaction
mixture, removing lactic acid and water as an overhead fraction, removing a
higher boiling bottom fraction and a recycling step” (Ans. 4). The Examiner
finds that to “use somewhat different but otherwise analogous process
parameters in an otherwise well-known purification technique would have
been obvious to [o]ne of ordinary skill in the art as the results, purified
product, would not have been unexpected” (Ans. 4).
Appellants contend that “[n]either O’Brien nor Drysdale teach or
suggest such a rectification column, let alone one mounted on the reactor as
recited [in claim 1]” (App. Br. 6). Appellants specifically argue that
“O’Brien fails to disclose a process according to the present invention since:
(1) there is no rectification column mounted on a lactide reactor in a manner
such that condensate from the column can be continuously returned to the
reactor; and (2) there is no vapor-phase purification of crude lactide.” (App.
Br. 6).
Appellants contend that “Drysdale also fails to disclose a process
according to the present invention since: (1) there is no rectification column

1
O’Brien et al., US 5,521,278, issued May 28, 1996.
2
Drysdale et al., US 5,236,560, issued Aug. 17, 1993.
Appeal 2011-003179
Application 10/582,280

4
mounted on a lactide reactor in a manner such that condensate from the
column can be continuously returned to the reactor; and (2) the feed stream
to the purification step (distillation) is a liquid condensate and is not a
vapor.” (App. Br. 7).
Appellants contend that the “the Examiner is attempting to argue one
teaching of O’Brien--that of condensing a vaporous reaction mixture and
fractionating the resulting condensate--is the equivalent of two different
steps of the present invention” (App. Br. 10).
The issues with respect to this rejection are: Does the evidence of
record support the Examiner’s conclusion that O’Brien and Drysdale render
obvious the method of claim 1?
Findings of Fact
1. O’Brien teaches a process for manufacturing purified lactide
which comprises the step:
Contacting the molten condensation polymer with an alkali
metal-free depolymerization catalyst in a cracking zone
operated at a liquid temperature no higher than 240° C. and
pressure sufficient to effect cracking of the molten
condensation polymer with the concomitant formation of (1)
a vaporous reaction mixture containing water, lactic acid,
lactide and entrained heavy oligomers and (2) molten liquid
heavy ends containing heavy oligomers

(O’Brien, col. 2, ll. 45-53)
2. O’Brien teaches a next step of “[r]emoving the vaporous
reaction mixture from the cracking zone at a rate such that the average
residence time of the lactide vapor within the cracking zone is less than 15
seconds” (O’Brien, col. 2, ll. 54-57).
Appeal 2011-003179
Application 10/582,280

5
3. O’Brien teaches a next step of “[c]ondensing the vaporous
reaction mixture and fractionating the condensate therefrom whereby lactic
acid, water and minor amounts of lactide are removed as vapor overhead,
concentrated lactide is removed as a liquid side stream and the heavy ends
are removed as molten liquid” (O’Brien, col. 2, ll. 58-62).
4. O’Brien teaches that
The vapor overhead stream from the oligomer cracker
contains substantial quantities of lactide. However, the
stream also contains substantial quantities of impurities such
as water, light decomposition products and entrained liquids
such as oligomers and other heavy ends, which must, of
course, be separated from the lactide. In the process of the
invention, this is preferably done in a two-stage operation
which involves condensing the cracker overhead to separate
the more volatile materials and then fractionally distilling
the lactide-enriched condensate.

(O’Brien, col. 8, l. 60 to col. 9, l. 3).
5. O’Brien teaches that “[s]ieve plate distillation trays, each
bearing a liquid layer of unconverted oligomer, have been found to be very
effective to mix the feed, vapor and liquid intimately and thus to improve
reaction efficiency” (O’Brien, col. 8, ll. 5-8).
6. Drysdale teaches that “impure cyclic ester as defined can be
separated from its impurities and obtained thereby as polymer grade material
by distillation means alone, more particularly by fractional distillation at
temperatures and pressures that minimize acid-producing side reactions. The
solventless distillation process of this invention is surprisingly effective”
(Drysdale, col. 2, l. 66 to col. 3, l. 4).
Appeal 2011-003179
Application 10/582,280

6
7. Drysdale teaches “means for recycling the various vapor and
liquid streams along the process loop” (Drysdale, col. 3, ll. 20-21).
8. Drysdale teaches that the “overhead stream exiting line 3,
which is rich in water and lactic acid and may contain lactide can be
dehydrated if necessary and fed to an oligomerization reactor (not shown)
for conversion to a depolymerizable lactic acid oligomer as is known in the
art” (Drysdale, col. 6, ll. 34-38).
9. Drysdale teaches that “molten lactide condensed in 5 can be
further refined, if desired, to provide still lower-acid content material by
feeding the condensate from 5 through line 7 to a second fractionating
column 8” (Drysdale, col. 6, ll. 17-21).
10. Figure 2 of Drysdale is reproduced below:

“FIG. 2 is a schematic representation of an integrated fractional distillation
system” (Drysdale, col. 3, ll. 16-17).

Appeal 2011-003179
Application 10/582,280

7
Principles of Law
“In rejecting claims under 35 U.S.C. § 103, the examiner bears the
initial burden of presenting a prima facie case of obviousness. Only if that
burden is met, does the burden of coming forward with evidence or
argument shift to the applicant.” In re Rijckaert, 9 F.3d 1531, 1532 (Fed.
Cir. 1993).
“[R]ejections on obviousness grounds cannot be sustained by mere
conclusory statements; instead, there must be some articulated reasoning
with some rational underpinning to support the legal conclusion of
obviousness.” KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 418 (2007).
Analysis
The Examiner has not met the burden of presenting a prima facie case
of obviousness in this application. As Appellants correctly note, neither the
O’Brien nor Drysdale reference teaches “a rectification column having a
feed inlet at the lower end of the column and an overhead vapour outlet at
the upper end of the column, through the said feed inlet, said column being
mounted onto the reactor such that components from the vapour product
stream liquefying within the column are allowed to flow back into the
reactor” (emphasis added) as required by claim 1. As noted in the
Specification, a significant feature of Appellants’ invention is that the
rectification column, from which the desired lactide product is withdrawn at
the upper end, is “mounted with its lower end onto the reactor” such that the
non-lactide “components liquefying in the rectification column are allowed
to directly flow back into the reactor to enable re-participation in the
Appeal 2011-003179
Application 10/582,280

8
depolymerisation reaction,” which eliminates the use of a prior art purge
stream to improve lactide yield (Spec. 6).
We agree with the Examiner that O’Brien appears to teach recycling
of the liquefying components from a fractionating column to the original
reactor (O’Brien, col. 9, ll. 15-17 (“Heavy ends from the lactide distillation
can be recycled to the lactide vacuum distillation column or they can be
recycled to one of the dehydration stages.”) (emphasis added)). However ,
insofar as we can ascertain, O’Brien never teaches that the column should be
mounted onto the reactor, and the Examiner has not explained why an
ordinary artisan would have been prompted to adopt the configuration
recited in claim 1.
While Drysdale generally teaches that the “purge (heel) taken from
the bottom of the column, which is rich in oligomeric acids and contains
some cyclic ester can be recycled to the depolymerization step for
conversion to additional quantities of cyclic ester” (Drysdale, col. 5, ll. 53-
57), the Examiner does not identify, and we do not find, any teaching in
Drysdale that suggests mounting the column “onto the reactor” to allow
liquefying components from the vapour stream to flow directly back into the
original reactor as required by claim 1. At best, Drysdale teaches recycling
the bottoms stream 6 through a distinct line 15 rather than directly mounting
the column to the initial reactor (see FF 10).
The Examiner argues that “recycling reaction components back to a
reactor is an obvious expedient well-known to a person of ordinary skill in
the chemical arts” (Ans. 4-5).
Appeal 2011-003179
Application 10/582,280

9
We are constrained to agree with Appellants that this argument lacks
evidentiary support explaining why an ordinary artisan would have adopted
the configuration of claim 1, in which the lactide purification column is
mounted directly onto the reactor, since neither O’Brien nor Drysdale teach
this type of recycling. It is the Examiner’s burden to provide teachings from
the prior art of the elements being used to render the claim obvious.
Rijckaert, 9 F.3d at 1532. We are therefore constrained to reverse the
rejections in the absence of a teaching or suggestion of a rectification
column which would satisfy the requirements of claim 1 in either O’Brien or
Drysdale, or their combined teachings.
Conclusions of Law
The evidence of record does not support the Examiner’s conclusion
that O’Brien and Drysdale render obvious the method of claim 1.
SUMMARY
In summary, we reverse the rejection of claims 1-21 under 35 U.S.C.
§ 103(a) as obvious over O’Brien and Drysdale.

REVERSED
alw