Glycol Hot Melt Ink Jet Ink
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Gendler, PL: AUTHOR [+3]
Disclosed is a one-phase hot melt ink jet ink composition comprising a lower MW glycol, a natural or synthetic wax, and surfactant at sufficient concentration to form a one-phase melt above 40oC. The surfactant can be ionic or non-ionic.
Glycol Hot Melt Ink Jet Ink
a one-phase hot melt ink jet ink composition
comprising a lower MW glycol, a natural or synthetic wax, and
surfactant at sufficient concentration to form a one-phase melt above
40oC. The surfactant can be ionic or non-ionic.
quality thermal ink jet (color) printing that is
substrate independent, an ink is desired which contains a "bubble
former", has a low viscosity at operating temperatures, and
solidifies on contact with paper. We now disclose a solid phase
change ink which is a glycol-in-oil microemulsion in which the low MW
glycols so chosen are also "bubble formers", and the continuous oil
phase is a solid natural or synthetic wax.
jet printing the ink must contain a "bubble former"
(i.e., a material that will volatilize and form a bubble in a thermal
jet heater). Although water is the most ubiquitous "bubble former",
retaining water in a formulation at the nozzle during dormancy is a
maintenance problem. At the elevated temperatures of the operating
printhead, the water is likely to evaporate from the nozzle. We find
that when the water content of the microemulsion is below 8 wt% of
the formulation, jetting no longer occurs in a thermal jet head. We
also find that replacing the water with 50% water/glycol mixtures
noticeably improves printhead maintenance. Since the equilibrium
amount of glycol/water ratios at the elevated temperature of the
fluid in the nozzle is expected to be at greater than 75%
glycol/water, experimenting with formulations containing glycols in
place of the water is promising.
glycol (EG), diethylene glycol (EG2), and propylene
glycol (PG, aka 1,2-propanediol) do not have the evaporation problem
water does. These lower MW glycols and glycol ethers are, like
water, immiscible with natural and synthetic waxes. The literature
reports [*] that the polar organic molecules such as these low MW
glycols are similar to water and can form a single phase with
normally non-miscible hydrocarbons by microemulsification with
sufficient amounts of a suitable surfactant.
We find that,
indeed, we can make one-phase systems of mixtures
of these lower MW glycols with waxes by the use of surfactants.
disclose a similar microemulsion in which the water is
replaced with one, or a mixture, of the lower MW glycol "bubble
formers", ethylene glycol, diethylene glycol and 1,2 propanediol. To
obtain a single phase at the operating temperature requires different