| 摘要 |
An agressively tacky pressure sensitive adhesive tape has a backing which is a transparent, rigid, tensilized cross streched, so as to be cross-toughened, film consisting essentially of unplasticized polyvinyl chloride, having a thickness of from 0,025 to 0,050 mm., a lengthwise stiffness modulus of at least 320 x 105 grams per square centimetres of cross-sectional area measured at 1% elongation, a lengthwise elongation at break of less than 100%, a crosswise elongation at break of at least 25%, a lengthwise tensile strength at break of at least 900 kilograms per square centimetre, and a crosswise tensile strength at break of at least 275 kilograms per square centimetre; the said film not having been subjected to a temperature above 120 DEG C. during or after the tensilizing process. "Rigid" designates a film having a high stiffness modulus value and which is capable of retaining its shape under normal tape manufacturing and use conditions. "Tensilized" indicates that the film has been stretched to orient its polymer molecules. The backing may be coated on one or both surfaces with a primer prior to the application of the adhesive. The uncoated side of the backing may be coated with a low adhesion back-size. The primer may contain a butadiene-styrene-acrylonitrile, terpolymer or a pure hydrocarbon polyterpene tackifying resin. The low adhesion back-size may contain the reaction product of N-octadecyl isocyanate and polyvinyl alcohol. The adhesive composition may contain crude rubber; pure hydrocarbon polyterpene resin, iso-octyl acrylate-acrylic acid copolymer, smoked rubber, butadiene-styrene copolymer, and ethyl vinyl ether polymer. The term "polyvinyl chloride" includes both homopolymers and copolymers with comonomers in small proportions serving to modify the properties without impairing the essential characteristic of the strict homopolymer. |
