CONTINUOUS BULK-POLYMERIZATION OF METHYL-METHACRYLATE USING VERY SHORT-LIFE INITIATOR

A simple and unique process for the continuous bulk polymerization of methyl methacrylate (MMA) by CSTR reactor was developed as a result of an investigation using a very short-life radical initiator. Advantages of the new process are as follows: (1) MMA conversion decreases with a rise in the reaction temperature. As a result, uncontrollable acceleration of the rate of reaction is avoided and MMA conversion is self-controlled and kept constant. (2) Initiator concentration in the reaction mixture is negligibly small compared with that of the feed stream (about 1/1000). This makes it possible for MMA conversion to be held constant during temporary shut-down of the continuous operation. As a result, not only material loss and energy loss but also troublesome operation for shut-down is avoided. (3) The half-life period of the initiator becomes shorter than the time for complete mixing, and consequently MMA conversion is changed by impeller speed. This leads to decrease in utilization efficiency of the initiator and compensates for acceleration of the rate of reaction by the gel-effect. As a result, MMA conversion can be controlled accurately by addition of AIBN solution using an automatic flow-rater.