Polychrome
makes sensitizers By Mr. Bob Gumbinner
On
the Newark property of Cellomer, we had a building in which we made
the negative plate sensitizer, formaldehyde-diazoparadiphenylamine
complex. This was made by reacting paraformaldehyde with the
diazoparadiphenylamine in concentrated sulphuric acid at 35°F and
dropping it on ice to make a 2% solution of the diazo which was
filtered. The diazo was precipitated by adding a saturated solution
of zinc chloride. This was filtered and dried. By precipitating the
diazo from the 2% solution with MS-40 we obtained an organic soluble
diazo. We started to make Polychrome Fotomer subtractive plates by
mixing this diazo with epoxy resins. To increase the length of the
press run we tried a number of different formulations. Bill Rowe
developed a polyester resin which when added to the epoxy resins and
a polyvinyl formal resin gave us an excellent presensitized
subtractive plate. One feature that we were able to obtain that our
competitors didn’t was that when the coating was removed from the
non-image area of the plate it did not particulate and gum up so that
when the plates were develop by passing through a machine with a
brush to remove the non-exposed coating we did not need to use a
filter. When our plant in Clark was ready for occupancy, Bill Rowe
moved his laboratory there since he lived in the next town,
Westfield, New Jersey.