Thermally developable imaging materials have an outermost protective layer
that is composed of one or more hydrophilic film-forming components. The
predominant film-forming component is a negatively-charged latex polymer
that has negatively-charged ionic groups other than carboxy groups. The
latex polymer is present as latex particles that have been prepared in
the presence of a nonionic stabilizer in an amount of at least 0.5% (by
weight) that has an HLB value of 7 to 20. The nonionic stabilizer becomes
associated with the latex polymer particles. Both thermographic and
photothermographic materials can be prepared with such protective layers.