Process for forming improved protective eco-friendly pouch and packaging and products made therefrom
The present invention relates generally to a protective wrap and a protective envelope or pouch: made therefrom, as well as the apparatus and: process for forming such wraps and envelopes. Water-based heat-expandable adhesives (WBHEA) which include a plurality of heat-expandable microspheres are disposed in a pattern between, web substrates on a continuous, high speed manufacturing line to produce padded, insulated products: useful as envelopes, mailers and other protective packaging.
1. A method of manufacturing protective packaging material, comprising:
providing a first pair of web substrates that are sealed together at a first perimeter seal to define a first inner region extending in two orthogonal directions within the first perimeter seal, with a heat-expandable adhesive disposed in an amount within the first inner region sufficient to form a protective padded area when expanded;
providing a second pair of web substrates that are sealed together at a second perimeter seal to define a second inner region extending in the two orthogonal directions within the second perimeter seal, with the heat-expandable adhesive disposed in an amount within the second inner region sufficient to form a protective padded area when expanded, the first and second pairs of web substrates being overlaid on each other and merged by a seal to define an empty pocket therebetween with an opening of the pocket between edges of the seal;
simultaneously exposing the overlaid and merged first and second pairs of web substrates to RF radiation sufficiently to cause the heat-expandable adhesive to expand in the first and second inner regions to form the protective padded areas;
wherein the protective padded areas within the first and second inner regions extensively cover the pocket in the two orthogonal directions; and
processing the merged and overlaid first and second pair of web substrates after exposing to RF to provide a uniformity in thickness of the protective packaging material.
2. The method of claim 1 , further comprising sealing the first pair of web substrates to the second pair of web substrates along at least a portion of the perimeter seals to form a pocket between the first and second pairs of web substrates within the perimeter seals.
3. The method of claim 1 , wherein the heat-expandable adhesive has a viscosity range of about 500 cps to about 5,000 cps at about 25° C. to about 40° C.
4. The method of claim 1 , wherein the heat-expandable adhesive is deposited in the first and second inner regions in a pattern that allows sufficient space for expansion of the heat-expandable adhesive.
5. The method of claim 4 , wherein the pattern includes a plurality of discrete areas of the heat-expandable adhesive and that one or more bridges of the heat-expandable adhesive extend between at least two of the plurality of discrete areas.
6. The method of claim 4 , wherein the pattern of heat-expandable adhesive includes an array of discrete elements having a length and a width, the shortest of those dimensions being in the range of about 0.05 inches to about 2.0 inches and longest of those dimensions being in the range of about 0.2 to about 2.5 inches.
7. The method of claim 1 , wherein the heat-expandable adhesive includes a water-based polymer and a plurality of heat-expandable microspheres and has a total solids content of about 40% to about 70% by weight, that is, the dry weight, including the microspheres.
8. The method of claim 2 , wherein the sealing the first pair of web substrates to the second pair of web substrates includes applying pressure to facilitate sealing along at least a portion of the perimeter seals.
9. The method of claim 1 , wherein the heat-expandable adhesive includes an emulsion-based polymer including one or more of: starch, vinyl acetate ethylene dispersion, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetate/polyvinyl alcohol copolymers, dextrin stabilized polyvinyl acetate, polyvinyl acetate copolymers, vinyl acetate/ethylene copolymers, vinylacrylic, styrene acrylic, acrylic, styrene butyl rubber, and polyurethane.
10. The method of claim 1 , wherein the heat-expandable adhesive includes a plurality of heat-expandable microspheres having an initial expansion temperature range of from about 35° C. to about 110° C., and a maximum expandable temperature range of about 50° C. to about 150° C.
11. The method of claim 1 , wherein the heat-expandable adhesive includes heat-expandable microspheres that include a polyacrylonitrile shell and a hydrocarbon core.
12. The method of claim 1 , wherein:
the heat-expandable adhesive includes a water-based polymer and a plurality of heat-expandable microspheres; and
the RF radiation is applied at frequencies which generate sufficient heat to activate the expansion of the heat-expandable microspheres and coalesce the water-based polymer.
13. The method of claim 1 , wherein the RF radiation is applied at frequencies of about 14 MHz to about 41 MHz.
14. The method of claim 1 , wherein the one or more of the web substrates includes a cellulosic material.
15. The method of claim 14 , wherein the cellulosic material includes a paper having a weight basis of about 10 lbs to about 60 lbs.
16. The method of claim 15 , wherein the cellulosic material has a thickness of about 0.002 in to about 0.010 in.
17. The method of claim 1 , wherein the substrate includes one or more of: fiberboard, corrugated board, kraft paper, and coated paper.
18. The method of claim 1 , wherein a thickness of the first pair of web substrates and a thickness of the second pair of web substrates are uniform prior to exposure to RF.
19. The method of claim 1 , wherein the heat-expandable adhesive includes an additive which includes one or more of the following: plasticizers, accelerants, tackifiers, humectants, preservatives, antioxidants, biocides, fillers pigments, dyes, stabilizers, rheology modifiers, and polyvinyl alcohol.
20. The method of claim 1 , wherein:
the first and second pairs of web substrates are overlaid on each other such that the first and second inner regions are overlaid on each other; and
the overlayed first and second regions are simultaneously exposed to the RF radiation.
21. The method of claim 1 , further comprising evaporatively venting water vapor produced as a byproduct of the expansion of the heat-expandable adhesive.
22. The method of claim 21 , wherein the first and second pairs of web substrates include one or more vents communicating the inner regions to an exterior of the pairs of web substrates.
23. The method of claim 1 , further comprising overlaying the first and second inner regions for the exposing to the RF radiation.
24. The method of claim 1 , wherein the heat-expandable adhesive includes a plurality of pre-expanded microspheres configured not to decompose with the exposing to the RF radiation.
25. The method of claim 1 , wherein the heat-expandable adhesive is maintained uncompressed within the first inner region.
26. The method of claim 1 , wherein the heat-expandable adhesive is maintained uncompressed within the second inner region.
27. The method of claim 1 , further comprising cutting the web substrates of the first or second pairs of web substrates into discrete lengths.
28. The method of claim 2 , wherein the first and second web substrates are unsealed to each other along a portion of the perimeter seals, forming an opening into the pocket.
29. The method of claim 28 , further comprising a closure flap positioned along one of the pairs of web substrates configured to close off the opening to the pocket.
30. The method of claim 9 , wherein the heat-expandable adhesive includes a plurality of heat-expandable microspheres having an initial expansion temperature range of from about 35° C. to about 110° C., and a maximum expandable temperature range of about 50° C. to about 150° C.
31. The method of claim 1 , wherein the heat-expandable adhesive is deposited in the first and second inner regions in a pattern that provides discrete areas of heat-expandable adhesive in a width direction and a length direction of the first and second pairs of web substrates.
32. The method of claim 1 , wherein the first and second inner regions extend continuously in a width direction and a length direction of the first and second pairs of web substrates.
33. The method of claim 1 , wherein the protective padded areas cover the entire pocket in the two orthogonal directions.
34. A method of manufacturing protective packaging material, comprising:
providing a first pair of web substrates that are sealed together at a first perimeter seal to define a first inner region extending in two orthogonal directions within the first perimeter seal, with a heat-expandable adhesive disposed in an amount within the first inner region sufficient to form a protective padded area when expanded;
providing a second pair of web substrates that are sealed together at a second perimeter seal to define a second inner region extending in the two orthogonal directions within the second perimeter seal, with a heat-expandable adhesive disposed in an amount within the second inner region sufficient to form a protective padded area when expanded, the first and second pairs of web substrates being overlaid on each other and merged by a seal to define an empty pocket therebetween with an opening of the pocket between edges of the seal; and
simultaneously exposing the overlaid and merged first and second pairs of web substrates to RF radiation sufficiently to cause the heat-expandable adhesive to expand in the first and second inner regions to form the protective padded areas;
wherein the protective padded areas within the first and second inner regions extensively cover the pocket in the two orthogonal directions;
wherein the heat-expandable adhesive is deposited in the first and second inner regions in a pattern that allows sufficient space for expansion of the heat-expandable adhesive; and
wherein the pattern of heat-expandable adhesive includes an array of discrete elements having an aspect ratio within the range from 0.2 to 10.