Reformulated Loctite SF 770 Primer. The new formulations have been upgraded with more globally acceptable raw materials, and the performance properties and shelf lives of the products remain consistent with existing Henkel Quality Specifications. LOCTITE® SF 770 is a primer used to make polyolefin and other low energy surfaces suitable for bonding with LOCTITE® cyanoacrylate adhesives. On such treated surfaces the cured performance of cyanoacrylate adhesives is generally similar to that described in the TDS for the relevant adhesive. It is only recommended for difficult to bond substrates which include polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and thermoplastic rubber materials. LOCTITE® SF 770 is not recommended in assemblies where high peel strength is required.