The physical blowing agent core is encapsulated within a shell or skin that will...http://www.google.com/patents/US6890964?utm_source=gb-gplus-sharePatent US6890964 - Combining a premixed epoxy resin containing an encapsulated solvent foaming agent core with H3PO4, applying to a member such as an automobile frame or body, and softening the capsule to release the foaming agentAdvanced Patent Search