Flexible Heat Conductor

Does anyone know a material or finishing which is flexible and thermal conductive.

It will be used on aluminium sealbars for plastic pouches and sealed in connectors.

Since you didn't supply many details, I'll assume you want a material attached to the aluminum seal bars to act as a heat transfer and pressure pad. When I worked for a medical instrument manufacturer, our sealers had a simple silicone rubber pad that had a high tempereature adhesive on one side. We tried both glass reinforced and unreinforced with similar results. We bought the material in sheets and cut to size. Sorry, but I don't know the manufacturer. Although silicone rubber isn't such a good heat conductor, the pads are thin enough to require only a short heat-up time, and then hold the heat very well.