Process for encapsulation of cellulose based substrates using adhesive
A method for encapsulating a cellulose based substrate with polymeric film involves applying an adhesive to at least one of the respective films and providing a pressure differential between an environment defined between the films and an environment external to the films so that conformance of the films to the cellulose based substrate is promoted. The cellulose based substrate is encapsulated by the polymeric films and the films are sealed around the peripheral edges of the cellulose based substrate as well as edges that are defined by slots and cutouts.
1 . A method for encapsulating a cellulose based substrate with a polymeric film, the method comprising:
providing a cellulose based substrate, the cellulose based substrate having a first surface, a second surface opposite the first surface, and a cellulose based substrate periphery;
providing a first polymeric film;
applying an adhesive to at least a portion of the first polymeric film;
providing a second polymeric film;
positioning the first polymeric film treated with adhesive adjacent the first surface of the cellulose based substrate such that the first polymeric film extends beyond the cellulose based substrate periphery;
positioning the second polymeric film adjacent the second surface of the cellulose based substrate such that the second polymeric film extends beyond the cellulose based substrate periphery, the first polymeric film and second polymeric film defining an envelope that substantially encapsulates the cellulose based substrate; and
providing a pressure differential between an environment within the envelope and an environment exterior of the envelope.
2 . The method of claim 1 , further comprising the step of applying adhesive to at least a portion of the second polymeric film.
3 . The method of claim 1 , wherein the step of providing a pressure differential includes sequentially exposing the envelope to a first pressure environment and a second pressure environment, pressure of the first pressure environment being different than the pressure of the second pressure environment.
4 . The method of claim 1 , further comprising the step of bonding a portion of the first polymeric film that extends beyond the cellulose based substrate periphery to a portion of the second polymeric film that extends beyond the cellulose based substrate periphery with the adhesive.
5 . The method of claim 1 , wherein the cellulose based substrate is a container blank.
6 . The method of claim 5 , wherein the container blank includes features selected from slots, cutouts, and scores.
7 . The method of claim 1 , wherein the cellulose based substrate comprises inner packings for a container selected from U-boards, H-boards and corner boards.
8 . The method of claim 1 , wherein the first polymeric film and second polymeric film comprise identical structures and composition.
9 . The method of claim 1 , wherein the first polymeric film and second polymeric film are different in structure.
10 . The method of claim 1 , wherein the first polymeric film and the second polymeric film are different in composition.
11 . The method of claim 1 , further comprising the step of trimming the first polymeric film and/or the second polymeric film.
12 . The method of claim 11 , wherein the step of trimming is carried out using a laser.
13 . The method of claim 1 , further comprising the step of treating the first polymeric film to increase its ability to be wet by the adhesive.
14 . The method of claim 13 , wherein the step of treating the first polymeric film to increase its ability to be wet by the adhesive comprises a corona treatment.
15 . The method of claim 1 , further comprising reducing the resilience of a portion of the cellulose based substrate adjacent the cellulose based substrate periphery.
16 . The method of claim 1 , further comprising the step of reinforcing selected portions of the first polymeric film by applying adhesive to such selected portions.
17 . The method of claim 1 , wherein the step of applying an adhesive to at least a portion of the first polymeric film further comprises applying adhesive to portions of the first polymeric film that extend beyond the cellulose based substrate periphery.
18 . The method of claim 17 , further comprising the step of adhering portions of the first polymeric film that extend beyond the cellulose based substrate periphery to portions of the second polymeric film that extend beyond the cellulose based substrate periphery.
19 . The method of claim 6 , further comprising the step of bonding the first polymeric film to the second polymeric film adjacent the cutouts or slots.