Polyvinyl chloride insulating tape, e.g. for pipes - is coated with primer contg. plasticising polymer and bitumen and with self-adhesive layer contg. synthetic rubber

Insulating tape consists of (a) a 0.2-0.5 mm. thick PVC carrier foil, opt. contg. 6-14wt.% bitumen, coated with (b) a 0.05-0.1mm thick primer layer contg., by wt., 5-20% synthetic rubber, 10-25% plasticising and adhesion-improving polymer (I), esp. an isobutylene-butadiene-cis/transbutene terpolymer having mol.wt. 500-1200, 0.1-1% bactericide, 55-85% bitumen or a mixt. of bitumen and pyrolysis resin and (c) a 0.05-0.1 mm. thick self-adhesive layer contg. 70-100% synthetic rubber, 0-16% bitumen and 0-14% talcum. The tape can be used for protecting subterranean pipe conduits, metal articles and concrete bodies against corrosion and water. The rubber components improve coated foil flexibility, heat-stability, plasticity, tear-strength and self-adhesion. (I) prevent migration. No intermediate layer, e.g., silicone oil-impregnated paper, is needed. Overlaps seal well after applying the foil. Physical data achieved may be elongation at break 250%; tear strength 234 kp/cm2; dielectric strength 24 kV/mm., resistivity 1.1 x 1014 ohm.cm., cold water absorption 0.12wt.% after 24 hrs. at 23 degrees C; steam permeability 2.3 g./m2 24 hrs. at 23 degrees and 100% RH.