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AssigneeMinnesota Mining and Manufacturing Company
InventorsWayne K. Morris, Richard L. Sheehan, Jr., Donald L. Pochardt
Estimating the term…
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.
A method of forming an area of weakness in a web of nonwoven thermoplastic fibers comprising the step of applying sufficient energy at an ultrasonic frequency in a concentrated area of said web to change the fibers forming the web to a film.
A method of forming a line of weakness in a web of nonwoven thermoplastic fibrous material comprising the steps of moving a length of a said web through a nip formed between an anvil and an ultrasonic horn and concentrating sufficient ultrasonic energy along a narrow band to impart sufficient heat along said band to said web to change said fibrous material to a film of tensile strength less than the fibrous material in the area of said band.
A method of forming a tear strip easy opening device on an envelope formed of a tough web material comprising nonwoven thermoplastic fibers comprising the steps of
An envelope formed of a tough web material of nonwoven thermoplastic fibers having a front panel and a back panel with the front panel extending from the bottom of the envelope a distance greater than the back panel to form a flap, and a pair of score lines formed in the envelope flap adjacent the envelope which score lines and the surrounding area of the envelope are covered by a length of reinforcing tape, which envelope flap and reinforcing tape have slits adjacent one end of the score lines.
Dependencies are inferred from the claim text.