Sealing material

A packer seal comprising

• a cross-linked fluororubber layer obtainable by cross-link-molding a fluororubber composition containing a fluororubber (A) and a carbon black (B),
• the cross-linked fluororubber layer having a loss modulus E″ of 600 to 6,000 kPa determined by a dynamic viscoelasticity test under conditions of measurement temperature:
• 160° C., tensile strain:
• 1%, initial force:
• 157 cN, and frequency:
• 10 Hz,
• wherein the fluororubber (A) is at least one copolymer selected from the group consisting of a vinylidene fluoride (VdF)/hexafluoropropylene (HFP) copolymer, copolymer of VdF/fluorine-containing monomer (2) of formula (2):
• CH2═CFRf (2)
• wherein Rf is a C1-C12 linear or branched fluoroalkyl group, and VdF/perfluoro(alkyl vinyl ether) (PAVE) copolymer,
• the VdF/HFP copolymer consists of a VdF repeating unit and a HFP repeating unit, and the VdF/PAVE copolymer consists of a VdF repeating unit and a PAVE repeating unit and
• the carbon black (B) comprises at least one carbon black selected from the group consisting of SAF-HS, SAF, N234, ISAF, ISAF-LS, ISAF-HS, N339, HAF-LS, HAF-HS, HAF, N351 and LI-HAF.