| 摘要 |
963,362. Making perforated plastic films. KENDALL CO. July 10, 1961 [Aug. 8, 1960], No. 41844/63. Divided out of 963,361. Heading B5A. [Also in Division B2] A method of perforating an adhesive tape 65 consisting of a backing constituted by an imperforate thermoplastic film 41 having on one side a coating 49 of pressure-sensitive adhesive and faced with a releasable facing sheet 67, comprises passing the film and facing sheet through the nip between a heated knurled roll 61 and a cooler smooth roll 60 with the facing sheet presented to the knurled roll. As shown in Fig. 2, a back-up sheet 66 is passed through the nip in contact with the surface of the film 41 facing the smooth roll 60, each boss 62 of roll 61 pressing facing sheet 67 into adhesive layer 49 which flows laterally and radially from the area of compression to form a perforation in layer 49. As shown in Fig. 3, continued application of pressure results in similar perforation of film 41 with the formation of annular bead 43. Neither facing sheet nor backup sheet is perforated. The film may be of polyvinyl chloride plasticized with a mixture of a sebacic acid polyester and epoxidized soybean; the releasable facing sheet may be of " Cellophane " (Registered Trade Mark); the back-up sheet may be of high-density polyethylene; and the adhesive may contain pale crepe rubber, tackifier resin, e.g. a blend of a glycerol ester of hydrogenated rosin, dimerized abietic acid and pentaerythritol ester of hydrogenated rosin, and age-resistors, e.g. a mixture of polymerized trimethyl dihydroquinoline, diorthotolyl ethylenediamine, and a condensation product of acetone and aniline. |
