am300975r_si_002.mpg (1.55 MB)
Super Toner and Ink Repellent Superoleophobic Surface
media
posted on 2012-08-22, 00:00 authored by Hong Zhao, Kock-Yee LawOffset of imaging material from a fuser surface to paper
during
fusing is highly undesirable in printing. Here the wetting and repellent
characteristics of three imaging materials (a solid wax ink, a waxy
polyester toner, and a polyester toner) in their molten states have
been studied on three model print surfaces: a transparency (surrogate
for paper), a PTFE film, and a model superoleophobic surface, with
the aim of assessing their performance in fusing. The superoleophobic
surface, with water and hexadecane contact angles of ∼156°
and sliding angles at ∼10°, comprises 3 μm diameter
pillar arrays on silicon wafer and was fabricated by photolithography
followed by surface modification with a fluorosilane. The contact
angles of the three imaging materials range from 40 to 79° on
the transparency and the sessile drops do not slide even at 90°
tilted angle, indicating that they all wet, adhere, and pin on the
transparency. Although the contact angles of the three imaging materials
are slightly higher (63–85°) on PTFE, the sessile drops
do not slide on PTFE either. Because PTFE is widely used as a fuser
surface material in combination with different waxy imaging materials
commercially, we attribute the successful implementation of PTFE to
the use of the wax additive. With the superoleophobic surface, there
is a dramatic increase in advancing and static contact angles for
all three imaging materials. The advancing and static contact angles
are in the 150–168° range for waxy toner, indicative of
superhigh repellency. Although the advancing and static contact angles
for the polyester toner decrease slightly at 147 and 130°, respectively,
the repellency is still very high. More importantly, the sessile drops
of all three imaging materials are mobile upon tilting and they all
have high receding contact angles. The overall results suggest that
the adhesion between the superoleophobic surface and the ink and toner
materials are very small relative to those with paper and PTFE. The
important of high repellency and low adhesion to offset performance
is discussed.