Methods and apparatus for manufacturing fiber-based microwavable food containers
Methods and apparatus for manufacturing a microwavable food container include: forming a wire mesh over a mold comprising a mirror image of the microwavable food container; immersing the wire mesh in a fiber-based slurry bath; drawing a vacuum across the wire mesh to cause fiber particles to accumulate at the wire mesh surface; and removing the wire mesh including the accumulated fiber particles from the slurry bath; wherein the slurry comprises a moisture barrier, an oil barrier, and a vapor barrier.
1. A slurry for use in vacuum forming a fiber-based microwavable food container, the slurry comprising:
an aqueous pulp mixture comprising fibers ground from at least one of old corrugated containers (OCC) and newsprint (NP);
a moisture barrier component in the range of 0.5%-10% of the slurry weight;
an oil barrier component in the range of 0.5%-10% of the slurry weight, where the oil barrier component is different from the moisture barrier component; and
a rigidity component in the range of 1%-5% of the slurry weight.
2. The slurry of claim 1 , further comprising a retention aid.
3. The slurry of claim 2 , wherein the moisture barrier is in the range of about 1.5%-4%, the oil barrier is in the range of about 1%-4%, and the retention aid is in the range of about 0.1%-0.5%.
4. The slurry of claim 3 , wherein the moisture barrier comprises alkyltene dimer (AKD).
5. The slurry of claim 4 , wherein the moisture barrier comprises alkyltene dimer (AKD) in the range of about 3.5%.
6. The slurry of claim 5 , wherein the oil barrier comprises a water based emulsion.
7. The slurry of claim 6 , wherein the water based emulsion comprises fluorine containing a fluorocarbon resin.
8. The slurry of claim 6 , wherein the water based emulsion comprises fluorine containing a fluorine polymer.
9. The slurry of claim 2 , wherein the retention aid comprises an organic compound in the range of 0.1-1% of the slurry volume.
10. The slurry of claim 1 , wherein the pulp mixture comprises old corrugated containers (OCC) in the range of about 70% and newsprint (NP) in the range of about 30%.
11. The slurry of claim 1 , wherein the rigidity component comprises a liquid starch.
12. The slurry of claim 11 , wherein the rigidity component further comprises a low charge liquid cationic starch.
13. The slurry of claim 1 , wherein the fibers exhibit a freeness in the range of 100-700.
14. The slurry of claim 1 , further comprising a vapor barrier comprising a long chain fluorine-based polymer.
15. The slurry of claim 14 , wherein the vapor barrier comprises in the range of about 0.1-3% of the slurry weight.
16. The slurry of claim 1 , wherein the rigidity component comprises modified polyamines configured to form both hydrogen and ionic bonds with the fibers.
17. The slurry of claim 1 , wherein the rigidity component comprises polyamide-epichlorohydrin (PAE) resin.
18. A fiber-based slurry for use in vacuum forming microwavable food trays, the slurry comprising:
a pulp mixture including at least one of old corrugated containers (OCC) and newsprint (NP);
a moisture barrier comprising alkyltene dimer (AKD);
an oil barrier comprising a water based fluorine emulsion; and
a rigidity component comprising liquid starch.
19. The slurry of claim 18 , further comprising:
a vapor barrier comprising a long chain fluorine-based polymer.