Appeal No. 1996-0823
Application No. 08/217,189
soluble in aqueous medium, consisting essentially of the steps of
dispersion of chitosan in an aqueous medium consisting essentially
of water,
subsequent hydroxyalkylation of the dispersed chitosan with epoxides
and
subsequent work-up of the N-hydroxyalkylchitosan,
which consists essentially of carrying out the hydroxyalkylation up to
an average degree of substitution of 2.0 and performing the work-up
of the N-hydroxyalkylchitosan by drying.
15. A N-hydroxyalkylchitosan obtained by the process as claimed in claim 1,
wherein the N-hydroxylkylchitosan has a residual content of hydroxyalkylation
reagent of less than 5 ppm.
The reference relied on by the examiner is:
Lang et al. (Lang) 4,835,266 May 30, 1989
The issue presented for review is whether the examiner erred in rejecting claims 1
through 4, 8 through 16 and 18 under 35 U.S.C. § 103 as unpatentable over Lang.
On consideration of the record, we shall sustain the examiner's rejection of claim
15. We do not, however, sustain the rejection of claims 1 through 4, 8 through 14, 16 and
18.
Claim 15
In column 10, example 4, Lang discloses a process for the preparation and work-up
of an N-hydroxypropyl-chitosan by (1) dispersing lower-molecular chitosan in water;
2
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