per minute8 whereby crystals of the diaryl carbonate form in
a residue of cooled solution;
[3] separating the residue of cooled solution from the
formed crystals of the diaryl carbonate; 9
[4] heating10 the separated crystals at a controlled
rate11 to their melt temperature, incrementally;
[5] separating sweat12 exuding from the heated
crystals in each increment; and
[6] collecting the melted crystals to obtain high
purity diaryl carbonate.13
Difference
8. As noted by the examiner, the difference between
Shafer and claim 1 is that claim 1 requires cooling at a
controlled rate, between about 0.01 to 1.0°C per minute, whereas
Shafer does not describe the precise rate at which cooling takes
place.
8 The examiner acknowledges that Shafer does not describe the rate at
which temperature is lowered (Paper 14, Examiner's Answer, page 4).
9 The crystalline diphenyl carbonate-phenol adduct is recovered from the
crystallization solution (col. 2, line 21--step (2); see also col. 4,
lines 3-6).
10 Shafer describes heating to preferably 60°C to 120°C (col. 2, line 56;
see also col. 4, lines 6-8).
11 According to Shafer, a crystalline diphenyl carbonate phenol adduct at
40°C was heated to 120° to effect separation of phenol (col. 4, lines 6-9). In
heating from 40°C to 120°C heating occurred over time. Phenol was constantly
being separated over time.
12 As noted in the previous note, phenol was removed over time during
distillation.
13 Ultimately, diphenyl carbonate was recovered (col. 4, line 9).
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