Process of forming a line of weakness in a sheet is formed of a material and the envelope sheet continues

摘要

A method of forming one or more score lines or bands of weakness in a web formed of nonwoven thermoplastic fibers requires the application of sufficient energy such as ultrasonic energy to narrow bands of the web to change the fibers to a film. An envelope formed of tough nonwoven thermoplastic fibers for use in shipping documents may be formed with an easy open device by forming score lines in the envelope and the envelope and, if necessary, may be reinforced in the area of the score lines by a strip of oriented pressure-sensitive adhesive reinforcing tape applied over the bands and adjacent surfaces of the envelope on the interior side of the envelope and a tear tape may be applied to the pressure-sensitive adhesive tape in the area between the bands to afford means for tearing the envelope at the bands. Cuts are conveniently formed at the ends of the tape and bands to increase the ease of opening.