| 摘要 |
<p>A composite sealing web comprises a bitumen compsn. layer incorporating a reinforcing core and a microperforated or porous surface sheet in polyethylene or similar material. The bitumen compsn. pref. has a softening pt. of at least 140 deg. C and contains a polyolefin-styrene cpd. The bitumen compsn. pref. comprises 52-78wt.% bitumen, 20-40% polyolefin and 2-8% styrene-butadiene elastomer. The reinforcement core is pref. a nonwoven polyester. The surface layer is 50-150 microns thick, is white or of a very light colour, has perforations of the order of 1/10 mm and is fusible at temps. at which a circulation top layer is applied. The prod. is used as a sealant in buildings and art and public works. It has good tear strength, puncture resistance, vapour permeability. The white surface layer reflects IR radiation and causes a redn. of over 20 deg. C in the temp. of the coating when exposed to the sun. The high softening pt. of the bitumen compsn. enables the latter to remain cohesive at temps. at which the top circulation layer is subsequently applied.</p> |
