Appeal 2007-2133
Application 10/790,502
includes heating the coating precursor on the fuel cell plate via radiant
(infrared) heating or convective heating to initiate polymerization,” in which
“[u]seful coating precursors include epoxy nitrile resins” (id. 4:5-8).
Appellants further disclose that “[d]epending on the type of reactive
components employed, the coating 132 can be cross-linked and/or
polymerized using any number of mechanisms, including oxidative curing,
moisture curing, thermal curing, high energy radiation curing (e.g.,
ultraviolet curing, electron beam curing), condensation and addition
polymerization, and the like” (Specification 6:8-12). Appellants disclose
reactive precursors, including acrylate resins, such as acrylated epoxies, and
epoxy resins,
can be cured using mechanisms described above, typically in
less than 45 minutes. Rapidly acting forms of radiation, which
required application for less than about 30 seconds, and in some
cases, for less than about 5 seconds are particularly useful.
Useful forms of radiation include ultraviolet (UV) radiation,
infrared radiation, microwave radiation, and electron beam
radiation. . . .
Exposing the coating precursor to high energy radiation
represents a particularly useful method of polymerizing the
reactive components in the coating precursors, offering
additional advantages for . . . coatings 132 over thermally-cured
reactive coating precursors. For instance, radiation cured
coating precursors can be cross-linked at much lower
temperatures (e.g., ambient temperature) than heat-cured
reactive coating precursors. This is an advantage when using
graphite composite fuel cell plates that can warp at temperatures
associated with heat-cured coatings. Radiation curing can
proceed via at least two mechanisms. In a first mechanism,
radiation provides fast and controlled generation of highly
reactive species (free radicals) that initiate polymerization of
unsaturated materials. In a second mechanism, radiation
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