Process for removing trace amounts of epichlorohydrin
from heat sensitive glycidyl products

A vertical jacketed column of 0.5 inch (1.27 cm) diameter was packed to a height of 18 inches
(45.72 cm) with fine wire mesh. The column was fitted with a jacket through which temperature
controlled polyethylene glycol was circulated to maintain the desired temperature in the column.
The column was fitted with a source of vacuum with vacuum gauge and an inlet at the bottom of
the column for introducing heated nitrogen as a purging gas. The nitrogen was heated to the
temperature of the column by an external heat source, and the rate of flow of nitrogen gas was
monitored and controlled by a flowmeter and control valve.

An epoxy resin or product containing glycidyl groups having over 2000 ppm of epichlorohydrin
present therein, was placed in a 1000 ml bottom-outlet flask fitted with a thermowatch control
mantle attached to the top of the packed column.

The flask and contents were then heated to a temperature sufficient to allow the epoxy resin or
product containing glycidyl groups to flow readily, but to a temperature insufficient to cause the
thermal decomposition thereof. This temperature was the same as that maintained in the packed
column and of the heated nitrogen purging gas. Heated nitrogen purging gas was admitted to the
column and a pressure (vacuum) of 410 mm Hg was imposed on the system. The heated epoxy
resin or product containing glycidyl groups was allowed to flow into the packed column by
gravity feed.

The stripped resin or product was collected at the bottom of the packed column with the flow rate
determined by timing the run and weighing the resin or product. The flow rate was adjusted to the
desired level by use of a metering valve on the bottom-outlet flask.

The stripped resin or product containing glycidyl groups was analyzed for epichlorohydrin content
to measure the effectiveness of the stripping step. After the analysis was completed, the stripped
resin or product containing glycidyl groups was passed through the packed column again for as
many times as was needed to reduce the level of epichlorohydrin to less than 10 ppm.

The results of these stripping experiments using four different starting materials showing the
number of passes through the column required to reduce the epichlorohydrin levels to less than 10
ppm.