Appeal No. 95-3624
Application No. 08/150,465
Many cyanine and related dyes are well known for
their ability to impart spectral sensitivity to a
gelatino silver halide system. The wavelength of
peak sensitivity is a function of the dye’s
wavelength of peak light absorbance. Whilst many
such dyes provide some spectral sensitisation in dry
silver formulations the dye sensitisation is often
very inefficient and it is not possible to translate
the performance of a dye in gelatino silver halide
systems to dry silver systems. The emulsion making
procedures and chemical environment of dry silver
systems are very harsh compared to those of gelatino
silver halide systems. The presence of large
surface areas of fatty acids and fatty acids salts
restricts the surface deposition of sensitising dyes
onto silver halide surfaces and may remove
sensitising dye from the surface of the silver
halide grains. The large variations in pressure,
temperature, pH and solvency encountered in the
preparation of dry silver formulations aggravate the
problem. Thus sensitising dyes which perform well
in gelatino silver halide systems are often
inefficient in dry silver formulations.
Second, the examiner does not refer to or supply any evidence
which supports his assertion regarding the stain. Nor does
the examiner refer to or supply any evidence which supports
his assertion regarding the problems associated with the use
of the infrared absorbing dyes in the photothermographic
material.
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