Ex Parte Biskup et al

Patent Trial and Appeal Board

Jan 29, 2015

12636925 (P.T.A.B. Jan. 29, 2015)

UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
__________

Ex parte KLAUS BISKUP, RAINER BRUNS, WOLFGANG LORENZ,
LARS PADEKEN, BERND PENNEMANN, FRITZ POHL,
ANDREAS RAUSCH, and FRIEDHELM STEFFENS1
__________

Appeal 2012-007445
Application 12/636,925
Technology Center 1600
__________

Before DEMETRA J. MILLS, CHRISTOPHER G. PAULRAJ, and
ROBERT A. POLLOCK, Administrative Patent Judges.

POLLOCK, Administrative Patent Judge.

DECISION ON APPEAL
Appellants appeal under 35 U.S.C. § 134(a) from the Examiner’s
rejections of claims 1–5. We have jurisdiction under 35 U.S.C. § 6(b).
We affirm.
STATEMENT OF THE CASE
Appellants’ invention relates to a process for the preparation of meta-
toluenediisocyanate by phosgenation of meta-toluenediamine in the gas
phase. (Spec. 1:7–8.) The Specification states that:

1 Appellants identify the Real Party in Interest as Bayer
MaterialScience AG. (App. Br. 1).
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In spite of the attempts to optimize the reaction of aromatic
amines with phosgene in the gas phase and thereby minimize
the formation of solids, there is a further need to improve the
gas phase phosgenation of aromatic diamines in order to
make it possible to phosgenate aromatic diamines in the gas
phase on a large industrial scale.
(Id. 6:13–19.) According to the Specification, “[i]t has now been found,
surprisingly, that the gas phase phosgenation of aromatic diamines on a large
industrial scale depends on the quality of the aromatic diamines.” (Id. 6:20–
23.)
Appellants do not argue the claims separately. Representative
independent claim 1 reads as follows:
1. A process for the preparation of m-toluene-diisocyanate
comprising feeding to a reactor
(1) a gaseous stream of phosgene and
(2) a gaseous stream of meta-toluenediamine generated by
vaporizing liquid meta-toluenediamine in at least one
evaporator in which
a) the liquid meta-toluenediamine fed to the evaporator
contains less than 0.5 wt.%, based on weight of meta-
toluenediamine, of toluenediamine residue, and in total
less than 0.2 wt. %, based on weight of meta-
toluenediamine, of ammonia and cycloaliphatic
amines, and
b) the liquid meta-toluenediamine fed to the
evaporator contains less than 20 ppm, based on weight
of meta-toluenediamine, of heavy metals, and
c) a ratio of amount of liquid meta-toluenediamine V
in kg present in the evaporator to amount of gas stream
M in kg/h leaving the evaporator is less than 2 h, and
d) the liquid meta-toluenediamine fed to the
evaporator is partly vaporized to an extent such that at
least 0.1 wt. %, based on weight of meta-
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toluenediamine, of the liquid meta-toluenediamine is
not vaporized, and
e) the non-vaporized meta-toluenediamine is not
included with the gaseous stream fed to the reactor
where the meta-toluenediamine is phosgenated in the gas
phase to form m-toluene diisocyanate.

The following ground of rejection is before us for review:
I. The Examiner rejects claims 1-5 under 35 U.S.C. §103(a) as
unpatentable over the combination of Sanders,2 Brady,3 Greenfield,4
and Marion.5
FACTUAL FINDINGS
We have reviewed Appellants’ contentions that the Examiner erred in
rejecting claims 1–5 as unpatentable over the cited art. (App. Br. 3–7; Reply
1–3.) We disagree with Appellants’ conclusions and adopt as our own the
factual findings and analysis set forth in the Final Rejection and Examiner’s
Answer. For emphasis, we highlight and address the following:
FF1. The Examiner finds that Sanders teaches “a method for producing m-
toluene-diisocyanate by a gas phase phosgenation of toluenediamine.”
(Ans. 5 (see also Sanders Abstract, ¶ 12).) The Examiner further finds
that Sanders teaches the use of “‘pure’ toluenediamine starting material []
for the gas phase phosgenation because using impure toluenediamine

2 Sanders et al., US 2007/0043233 A1, published February 22, 2007.
3 Brady et al., US 6,359,177 Bl, issued March 19, 2002.
4 Greenfield et al., 5,081,303, issued January 14, 1992.
5 Marion et al., US 6,547,933 B2, issued April 15, 2003.
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results in the formation of deposits and lower yields (paragraph 12, 4, 62
and 63).” (Id. 11.)
FF2. Sanders teaches an improvement to the process for the phosgenation
of amines in the gas phase, in which a specific type of heat exchanger, a
milli or micro heat exchanger, is used for the liquid heating, vaporization
and gas superheating of the amines. (Sanders, Abstract, ¶ 7.) When
other types of heat exchangers are used for heating and vaporizing the
amines and phosgene starting materials, “decomposition with elimination
of ammonia occurs, particularly in the vaporization and superheating of
aliphatic amines. This not only reduces the yield but also causes the
formation of deposits of ammonium chloride in pipes and the reactor in
the subsequent phosgenation reaction.” (Id. ¶ 4.) “To monitor chemical
changes in the amines, samples were analyzed by gas chromatography
and ammonia analysis at regular intervals. (Id. ¶ 62.) “A pressure
buildup occurring over time in conventional heat exchangers as a result
of deposits was observed for none of the amines used during the time of
the experiment.” (Id. ¶ 63.)
FF3. Brady discloses a process for separating a mixture of materials having
different boiling points, particularly mixtures containing different
isomers of an amine. (Brady, Abstract, 2:1–5.) “Any of the known
techniques and commercially available equipment may be used to carry
out separation of a starting mixture in accordance with the present
invention. The technique which is most typically used is distillation.”
(Id. 4:4–8.) Although the process can be used with “any mixture of
materials having sufficiently different boiling points to enable separation
by distillation. This process is, however, particularly useful for
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separating mixtures of amines, most preferably isomeric mixtures of
amines such as toluene diamine. (Brady, 3:48–53.) “In a particularly
preferred embodiment of this process, low boiling isomers of toluene
diamine are separated from a technical mixture generated in the course of
producing toluene diamine from dinitrotoluene.” (Id. 2:63–67.)
FF4. The Examiner finds that Brady teaches
a method of separating and purifying toluenediamine
(abstract), in which fractions having different boiling points
are separated into different streams with little or no by-
products present (column 2, lines 21-30). Brady et al. teaches
that the purified streams can contain 0.03 wt% of
toluenediamine residue (column 7, table 1, stream 4, residue
row, line 42) and 0 wt% of cycloaliphatic amines (HH-TDA:
methylcyclohexyldiamine and HH-Toluidine:
methylcyclohexylamine) (column 7, table 1, stream 4, HH-
TDA and HH-Toluidine rows, lines 39 and 41).
(Ans. 6.)
FF5. The Examiner finds that Greenfield teaches
toluenediamine produced from the hydrogenation of
dinitrotoluene (column 10, last paragraph) and that the metal
catalyst is removed by filtration (column 7, lines 55-65).
Greenfield et al. further exemplifies purified streams that
contain no metal catalyst in the diamine and amine product
streams, which are homologs of toluenediamine (column 8,
table 1, streams 26-29).
(Id. 6.)
FF6. The Examiner finds that Marion teaches that “the toluenediamine is
partly vaporized, in which 3% to 50% is not vaporized, which is not used
for phosgenation and fed back to the distillation column (column 3, lines
30-37; column 5, lines 33-47, 63-67).”
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ANALYSIS
The Examiner relies on Sanders as the primary reference, but
acknowledges that Sanders fails to explicitly teach that the liquid meta-
toluenediamine fed to the evaporator contains less than 0.2 wt% of ammonia
or less than less than 0.5 wt% of toluenediamine residue; less than 0.2 wt%
of cycloaliphatic amines; less than 20 ppm of heavy metals. (Ans. 5–6.)
The Examiner also finds that Sanders’s focus on the use of “pure”
toluenediamine for gas phase phosgenation provides “motivation to purify
the starting material amine in order to avoid the formation of deposits and to
have higher yields,” whereas the secondary references “teach the
purification and optimization of the purity of the amine, which can be used
in phosgenation reactions.” (Id. 11.) The Examiner finds that one of
ordinary skill in the art would find it obvious to optimize these limitations
“through routine and normal experimentation.” (Id. 7.)
Appellants argue that the Examiner errs in combining Sanders with
the secondary references, most particularly Brady, because Sanders
“discloses a gas-phase phosgenation process in which a specific type of heat
exchanger (i.e., a milli or micro heat exchanger) must be used to vaporize
the amines to be phosgenated” and “does not teach or suggest that it would
be possible to achieve the objective sought therein without the need to use
the specific reactors” (App.Br. 3), whereas Brady, takes a “completely
different approach[] to resolving the same problem” (see Reply 2).
Recasting this argument at page 2 of the Reply brief Appellants argue that:
There is no teaching in Brady et al that the amines separated
in accordance with the techniques disclosed therein would
make them "suitable" for the production of a polyisocyanate
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in the manner disclosed by Sanders et al without the need to
use the micro-evaporator required by Sanders et al.
We do not find Appellants’ argument persuasive. To the contrary, we
see no credible reason why one of ordinary skill in the art would not find it
obvious to improve upon the production of m-toluene-diisocyanate by gas
phase phosgenation of toluenediamine by using purified amines as starting
materials as taught by Sanders (FF1).
As an initial matter, the claims on appeal are neither limited to, nor
exclude, the use of milli or micro heat exchangers. Nor does a finding of
obviousness require that Sander’s phosgenation process (involving a
particular type of heat exchanger to vaporize the amine reactants) be
physically combinable with those same amine reactants purified according to
Brady.6 See In re Sneed, 710 F.2d 1544, 1550 (Fed. Cir. 1983). “Rather, the
test is what the combined teachings of the references would have suggested
to those of ordinary skill in the art.” In re Keller, 642 F.2d 413, 425 (CCPA
1981) (citation omitted).) Crediting the Examiner’s finding that Sanders
provides motivation for using “pure” starting material for the phosgenation
of amines in the gas phase, we find no error in the Examiner’s finding that
one of ordinary skill would look to the relevant secondary references to
optimize that purity—irrespective of the type of heat exchanger used to heat
and vaporize the reactants.

6 We nevertheless find no error in the Examiner’s finding that “Appellant's
arguments are not persuasive because the teachings of Brady et al. and
Sanders et al. are compatible and refer to different stages, for the purification
of starting material amine and then a phosgenation process using the purified
amine.” (Ans. 10.)
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Appellants further argue that none of the cited references teach or
suggest a phosgenation process in which “(1) the TDA contains less than 0.5
wt. % toluene diamine residue and less than 0.2 wt. % of cycloaliphatic
amines; (2) the TDA has less than 20 ppm of heavy metals; (3) the TDA is
partially vaporized with at least 0.1 wt. % TDA not being vaporized and not
being fed to the reactor; and (4) less than 0.2 wt.% ammonia is present in the
TDA.” (App. Br. 5; see also, e.g., Reply 3.) We do not find Appellants
argument persuasive.
“[T]he discovery of an optimum value of a variable in a known
process is normally obvious.” Exceptions to this rule include (1) the results
of optimizing a variable were unexpectedly good and (2) the parameter
optimized was not recognized in the prior art as one which would affect the
results. In re Antonie, 559 F.2d 618, 620 (CCPA 1977). Appellants do not
argue that either exception applies.
The Specification’s reference to prior art attempts “to optimize the
reaction of aromatic amines with phosgene in the gas phase and thereby
minimize the formation of solids” (Spec. 6:13), reinforces the Examiner’s
reasoned finding that Sanders’s focus on the use of “pure” toluenediamine
for gas phase phosgenation provides “motivation to purify the starting
material amine” according to the teachings of the secondary references. (See
Ans. 11.) As in the present case, “where the general conditions of a claim
are disclosed in the prior art, it is not inventive to discover the optimum or
workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456
(CCPA 1955). And given that the “discovery of an optimum value of a
result effective variable in a known process is ordinarily within the skill of
the art” (In re Boesch, 617 F.2d 272, 276 (CCPA 1980)), we agree with the
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Examiner’s conclusion that one of ordinary skill in the art would find it
obvious to optimize the claimed purity parameters to arrive at the ranges set
forth in Appellant’s claims. (See Ans. 7.) Appellants have not rebutted the
Examiner’s prima facie case by demonstrating unexpected results associated
with the claimed parameters.
SUMMARY
I. We affirm the Examiner’s rejection of claims 1–5 under § 35 U.S.C.
103(a) as unpatentable over the combination of Sanders, Brady,
Greenfield, and Marion.

TIME PERIOD FOR RESPONSE
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

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