Ex Parte Lorenz et al

Board of Patent Appeals and Interferences

Aug 3, 2010

12001905 (B.P.A.I. Aug. 3, 2010)

1

UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte WOLFGANG LORENZ, LARS PADEKEN,
BERND PENNEMANN, FRIEDHELM STEFFENS,
and LOTHAR WEISMANTEL
__________

Appeal 2010-004603
Application 12/001,905
Technology Center 1600
__________

Before DONALD E. ADAMS, DEMETRA J. MILLS, and
STEPHEN WALSH, Administrative Patent Judges.

MILLS, Administrative Patent Judge.

DECISION ON APPEAL1

This is an appeal under 35 U.S.C. § 134. The Examiner has rejected
the claims for obviousness. We have jurisdiction under 35 U.S.C. § 6(b).

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. § 1.304, or for filing a request for rehearing,
as recited in 37 C.F.R. § 41.52, begins to run from the “MAIL DATE”
(paper delivery mode) or the “NOTIFICATION DATE” (electronic delivery
mode) shown on the PTOL-90A cover letter attached to this decision.

Appeal 2010-004603
Application 12/001,905

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STATEMENT OF THE CASE
The following claim is representative.
Claim 1. A process for the preparation of toluene-diisocyanate, which
comprises
a) reacting toluenediamine with phosgene to form crude toluene-
diisocyanate,
b) purifying the crude toluene-diisocyanate by distillation to form
purified toluene-diisocyanate and a mixture comprising toluene-
diisocyanate and the distillation residue of toluene diisocyanate,
c) mixing said mixture comprising toluene-diisocyanate and the
distillation residue of toluene diisocyanate continuously with water at
a temperature of less than 230°C under an absolute pressure of less
than 30 bar, and allowing said mixture and water to react under said
conditions in one or more tubular reactors connected in series to form
toluenediamine,
d) optionally, purifying said toluenediamine formed in step c),
and
e) recycling at least a portion of said toluenediamine into the reaction in
step a).

The Examiner relies on the following prior art reference to show
unpatentability:
Schwarz et al. US 6,673,960 B1 Jan. 6, 2004

Grounds of Rejection
Claims 1-11 are rejected under 35 U.S.C. §103(a) for obviousness
over Schwarz.

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Discussion
ISSUE
The Examiner contends that “claim 1 is drafted in such a way that it
does not exclude the process for the preparation of toluene-diisocyanate and
toluenediamine having more than one type of the reactor” (Ans. 7). The
Examiner argues that Schwarz describes DE-A-2703313 which discloses
that hydrolysis of toluenediisocyanate is continuously carried out in a tube
reactor. (Id.)
Appellants’ sole contention is with regard to backmixing disclosed in
Schwarz. Appellants argue that “[i]t is evident to one skilled in the art from
the express disclosure of the Schwarz et al reference that backmixing is
necessary for the process described therein to be suitable for its intended
purpose. Without backmixing, it is apparent that solids form in the process.
The formation of solids is clearly undesirable and is described as being
"completely avoided" by intensive backmixing of the reaction mixture (see
column 2, lines 54-56)” (App. Br. 4).
The issue is: Does Schwarz disclose the claimed process steps
including a step of carrying out a hydrolysis in a tube reactor.

FINDINGS OF FACT
1. According to the Specification, “[b]ackmixed reactors which are
mentioned are stirred tanks, cascades of stirred tanks, a reaction
mixing pump, a pumping circulation with a static mixer and/or two
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component mixing nozzle, a jet loop reactor or a jet nozzle reactor.”
(Spec. 4.)

2. Backmixing means “(chemical engineering) The tendency of reacted
chemicals to intermingle with unreacted feed in reactors, such as
stirred tanks, packed towers, and baffled tanks.” McGraw-Hill
Dictionary of Scientific and Technical Terms, 6th edition, published
by The McGraw-Hill Companies, Inc. on –line,
http://www.answers.com/library/Sci%252DTech+ Dictionary-cid-
1029379
3. “Schwarz teaches that the synthesis of toluene diisocyanate (TDI) is
usually prepared by reacting toluenediamine (TDA) with phosgene.
This process has been known for a long time and has been extensively
described in the literature.” (Ans. 3, citing Schwarz, col. 1, ll. 10-15.)
4. Schwarz teaches the “ratio of TDI to residue from the distillation step
can be from 1 to 20%. See col. 1, lines 10-15. To improve the
reaction yield, the continuous backmixed reactor can also be
configured as a reactor cascade or as a combination of backmixed
prereactor and non-backmixed post-reactor, e.g. as a stirred tank with
a downstream tube reactor. See col. 3, lines 15-23.” (Ans. 3-4.)
5. “Schwarz teaches a process for hydrolyzing TDI distillation residues
by reacting the TDI distillation residue with water in a continuous or
semicontinuous process in a backmixed reactor in the presence of
hydrolysate. The distillation residue is converted into TDA and
carbon dioxide. It is not only the free TDI of the TDI distillation
residue which is converted into TDA, but, surprisingly, the other
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constituents of the TDI distillation residue are also dissociated to a
substantial extent, which leads to very high yields of TDA. For the
purposes of the present invention, "hydrolysate" refers to the reaction
products of the TDA residue with water.” (Id. at 4.)
6. Schwarz teaches “[t]he hydrolysis should preferably be carried out in
the simultaneous presence of hydrolysate and water. In such a
procedure, the formation of solids can, surprisingly, be completely
avoided. This is preferably effected by intensive backmixing of the
reaction mixture. The hydrolysis is preferably carried out at from 120
to 250º C. and at pressures of from 1 to 50 bar.” (Id.)
7. Schwarz teaches “[t]he pressure should preferably be selected so as to
be somewhat higher than the boiling pressure of the product
discharged from the hydrolysis reactor at reaction temperature. The
mass ratio of TDI residue to water is preferably from 4.8:l to 1:5,
more preferably from 1:1.0 to 1:3. See col. 2, lines 40-63.”(Id.)
8. “Schwarz teaches that the hydrolysis can be aided by the use of bases
such as alkali metal hydroxides and/or alkaline earth metal
hydroxides, e.g. sodium hydroxide, potassium hydroxide, magnesium
hydroxide, calcium hydroxide, magnesium oxide, calcium oxide,
ammonia or amines, or acids such as hydrochloric acid, hydrobromic
acid or sulfuric acid. When using alkali metal hydroxides, they are
preferably used in an amount of from 0.5 to 5.0% by weight, based on
the reaction mixture.” (Id. at 4-5.)
9. “The use of catalysts customarily used for the dissociation of
urethanes, e.g. solids of iron, zinc, tin and zirconium, likewise aids the
hydrolysis. The hydrolysate is taken continuously from the hydrolysis
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reactor and worked up. In the preferred solvent-free process, the
hydrolysate consists of a single phase.” (Id. at 5.)
10. Schwarz teaches “[t]he water which has been used in excess is first
separated off by distillation and the TDA is subsequently separated off
by distillation. When using water-soluble solvents, a major part of the
water can be separated off by carrying out a phase separation
beforehand. The water which has been separated off can in either case
be returned to the hydrolysis. The TDA obtained by means of the
hydrolysis can, after appropriate purification and work-up, either be
introduced into the phosgenation reactor of the TDI process or can be
added to the reaction mixture leaving the hydrogenation reactor in the
preparation of TDA by hydrogenation of dinitrotoluene.” (Id.)
11. Schwarz teaches “[t]he … process variant has the advantage that the
work-up step after the hydrolysis can be simplified or possibly
dispensed with entirely. The by-products of the hydrolysis can then be
removed from the process together with the TDA tar in the TDA
work-up step. See col. 3, lines 52-67 through col. 4, lines 1-15 and
Examples 1-4, 9 and 10.” (Id.)
12. “The difference between Schwarz and the instant claims is that
Schwarz mainly teaches the work-up of distillation residue from the
synthesis of toluene diisocyanate.” (Id.)
13. “Schwarz teaches recycling toluenediamine obtained by means of
hydrolysis into the phosgenation reactor of the TDI process.” (Id. at 5-
6.)
14. The Examiner concludes that it “would therefore have been obvious to
one of ordinary skill in the art at the time the invention was made to
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carry out the TDI synthesis reaction integrated with the hydrolysis of
TDI distillation residue to make use of the materials more effectively,
which leads to high yields of useful products, in particular TDA.” (Id.
at 6.)
15. In the background section of Schwarz is disclosed DE-A-2703313
which describes that the hydrolysis of toluenediisocyanate is
continuously carried out in a tube reactor. ((Schwarz, col. 1, ll. 52-58;
Ans. 7.)
16. Schwarz indicates that a “combination of backmixed pre-reactor and
a non-backmixed post-reactor, e.g., as a stirred tank with a
downstream tube reactor” may be used. (See, col. 3, ll. 15-20.)

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, 28
USPQ2d 1955, 1956 (Fed. Cir. 1993) (citations omitted). In order to
determine whether a prima facie case of obviousness has been established,
we consider the factors set forth in Graham v. John Deere Co., 383 U.S. 1,
17 (1966): (1) the scope and content of the prior art; (2) the differences
between the prior art and the claims at issue; (3) the level of ordinary skill in
the relevant art; and (4) objective evidence of nonobviousness, if present.
The interpretation of terms in a claim is a matter of law. In re
American Academy Of Science Tech Center, 367 F.3d 1359, 1363 (Fed. Cir.
2004. During prosecution before the Office, claims are to be given their
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broadest reasonable interpretation consistent with the Specification as it
would be interpreted by one of ordinary skill in the art. Id. at 1364.
“An essential purpose of patent examination is to fashion claims that are
precise, clear, correct, and unambiguous. Only in this way can uncertainties
of claim scope be removed, as much as possible, during the administrative
process.” In re Zletz, 893 F.2d 319, 322 (Fed. Cir. 1989). Moreover, it is
during prosecution that applicants have “the opportunity to amend the claims
to obtain more precise claim coverage.” American Academy, 367 F.3d at
1364.
ANALYSIS
The Examiner concludes that “claim 1 is drafted in such a way that
does not exclude the process for the preparation of toluene-diisocyanate and
toluenediamine having more than one type of the reactor” (Ans. 7). The
Examiner argues that in the background section of Schwarz is disclosed DE-
A-2703313 which describes that the hydrolysis of toluenediisocyanate is
continuously carried out in a tube reactor (id.).
Appellants argue that “[i]t is evident to one skilled in the art from the
express disclosure of the Schwarz et al reference that backmixing is
necessary for the process described therein to be suitable for its intended
purpose. Without backmixing, it is apparent that solids form in the process.
The formation of solids is clearly undesirable and is described as being
"completely avoided" by intensive backmixing of the reaction mixture (see
column 2, lines 54-56).” (App. Br. 4.) Appellants argue that it is not proper
to substitute tube reactors for backmixed reactors. (See App. Br. 5.)
We are not persuaded by Appellants’ argument. The claims use the
open ended language ‘“[c]omprising’… which means that the named
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elements are essential, but other elements may be added and still form a
construct within the scope of the claim.” Genentech, Inc. v. Chiron Corp.,
112 F.3d 495, 501, (Fed. Cir. 1997). Thus, the pending claims do not
exclude the possibility of inclusion of additional process steps such as
backmixing. Thus, to support the rejection before us, there is no
requirement of substitution of tube reactors for backmixed reactors as
alleged by Appellants (Br. 5; Reply Br. 2), they may both be used consistent
with the claim interpretation and the disclosure of Schwarz. Schwarz
indicates that a “combination of backmixed pre-reactor and a non-
backmixed post-reactor, e.g., as a stirred tank with a downstream tube
reactor” may be used. (See, col. 3, ll. 15-20.)
Schwarz further teaches that the hydrolysis step may use a heated
tube. (Schwarz, col. 3, 1. 35.) DE-A-2703313, mentioned in the background
of Schwarz discloses that it is known “that the hydrolysis of TDI is
continuously carried out in a tube reactor.” (Ans. 7.) While Schwarz teaches
that backmixing during the hydrolysis step is preferred, it is not required.
FF6.
Therefore it is known from Schwarz to carry out the hydrolysis of TDI
in a tube reactor, and additional steps of backmixing are not excluded from
the pending claim scope. Appellants have provided no evidence of
secondary considerations or unexpected results for the claimed process over
the process of Schwarz.

CONCLUSION OF LAW
The cited reference supports the Examiner’s obviousness rejection.

Appeal 2010-004603
Application 12/001,905

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TIME PERIOD
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).

AFFIRMED

alw

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