Arkema Inc. has commercialized Luperox F40M-SP, a scorch protected, 40% peroxide-EPDM masterbatch, developed exclusively for use in EPDM.  Despite the technical and commercial success of the SP grade, the technology was advanced to another level with the recent development of “SP2” (enhanced scorch protected) peroxide technology. This newer technology supports applications involving a wide range of elastomers that require even greater scorch time protection during compounding and crosslinking.

In this paper, we introduced two new SP2 (enhanced scorch protected) peroxides: DC40P-SP2 and F40P-SP2, based upon dicumyl peroxide and di(t-butyl­per­oxy)­di­iso­propyl­benzene. Data was presented showing the results of evaluation of SP2 peroxide technology in AEM, CPE, EPDM, EVA, EOM and HNBR.

In AEM, the DC40P-SP2 and F40P-SP2 provided a ~30% to ~50% increase in ts2 scorch times at reported cure temperatures with desirable tc90 cure times to maintain good productivity during injection, compression and/or transfer molding operations. A three-fold increase in ts2 scorch time was obtained with these peroxides at reported compounding temperatures, providing the possibility of cost-savings by going to a one-pass mixing operation or by increasing mixer speed, without the threat of scorch.

In CPE cable jacket, a blend of F40P-SP2 and MBM coagent provided a way to safely increase the extruder screw speed due to a six-fold increase in scorch protection at reported compounding temperatures, while doubling productivity by reducing the cure time without increasing the continuous vulcanization (CV) tube temperature.

In EPDM, both DC40P-SP2 and F40P-SP2 provided ~40% to ~50% improvements in scorch time at reported crosslinking temperatures, versus 15% for the F40M-SP grade previously commercialized specifically for EPDM. These two new SP2 grades are recommended for molding larger parts, increasing the number of prints per mold, and/or molding more intricate EDPM components. By simply replacing F40KE with F40M-SP in EPDM, end-users have successfully transitioned from two-pass to one-pass mixing of EPDM. We anticipate that DC40P-SP2 and F40P-SP2 will offer greater cost-savings in compounding EPDM.

In EVA-EOM blends for shoe soles, a blend of F40P-SP2 and TAC provided superior scorch time protection during cure and compounding, along with an 18% increase in productivity based upon tc90 cure time.

In HNBR, DC40P-SP2 and F40P-SP2 provided a ~20% increase in scorch time at reported cure temperatures. Data provided by researchers at Zeon Chemicals and R. T. Vanderbilt Company, Inc. confirmed good scorch time performance with no change in tc90. DuPont Spider Mold Flow tests confirmed a 17+% increase in mold fill at cure temperatures.