Appeal No. 96-3689
Application 08/325,914
25EC. As indicated, at relatively low concentrations, the viscosity increases with
increasing concentration. In these low concentration regions, spherical and rod micelles
are the predominant phase .... As concentration increases, viscosity peaks, and the
surfactant molecules are predominantly in the hexagonal liquid crystalline phase (repesented
by “C” ...). As concentration further increases, viscosity drops as the surfactant molecules
predominantly assume the lamellar liquid crystalline configuration (represented by “D” ...).
Accordingly, for the purposes of the present invention, the surfactant solution
coated onto the recording sheet at the time of printing is in a phase such that the aqueous
ink contacting the surfactant solution dilutes the surfactant solution to the extent necessary
to effect a phase change that results in an increase in viscosity in the surfactant solution.
For example, in a preferred embodiment of the present invention, the recording sheet
substrate is coated with a solution of the surfactant in the lamellar phase. Upon application
of an aqueous ink to the coating, the concentration of the surfactant is decreased by the
local dilution effect of the ink drop. This decrease in concentration shifts the surfactant to
the hexagonal liquid crystalline phase, and accordingly increases the viscosity of the
recording sheet coating in the area of the ink droplet. While not being limited to any
particular theory, it is believed to be possible that this local increase in viscosity on the
recording sheet decreases drying time and inhibits printing defects such as fuzzy line edges,
line growth, and intercolor bleed.
Clark’s Example 2 discloses a composition comprising water and ammonium laureth sulfate, a
surfactant within the scope of appellant’s claim 1 as noted, supra. The amount of water in the composition
is about 79% by weight while the amount of surfactant is about 0.015% by weight. In fact, the
concentration of surfactant disclosed by Clark in his cleaning composition does not exceed about 1% by
weight (col. 2, lines 45-48). As can be gleaned from Fig. 3, supra, these concentrations are nowhere near
the amounts illustrated in the Fig. 3 which are required to cause the phase changes recited in appellant’s
claims. For the foregoing reasons, the examiner’s rejection of claims 1-6, 9-15, 18-24 and 27
under 35 U.S.C. § 102(b) as anticipated by Clark is reversed.
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