| 摘要 |
Pressure-sensitive adhesive tape is made by coating a crystalline polypropylene film which has been biaxially oriented by stretching longitudinally to effect area-type orientation, and transversely, at its natural inherent draw ratio, to effect line-type orientation, with a pressure-sensitive adhesive composition. Examples of such compositions include one comprising 100 parts crude rubber and 75 parts polymerized beta-pinene resin of melting point 115 DEG C. and a zero acid number, e.g. that sold under the Trade Name "Piccolite S-115", and a 20% solids solution in heptane and ethyl acetate of a copolymer of 95,5 parts by weight isooctyl acrylate and 4,5 parts acrylic acid. The latter composition may be coated on paper over a layer of silicone release agent and transferred to the polypropylene film, which is previously primed by a corona discharge treatment. To facilitate unwinding, a low adhesion back size may be used, suitably a copolymer of 60 parts of octadecyl acrylate and 40 parts of acrylic acid. |
