Repulpable and recyclable composite packaging articles and related methods
Unexpectedly unique and environmentally friendly composite material structures, storage articles fabricated therefrom, and related methods. The composite structure includes at least one or more fiber-containing layers, such as fiberboard or other layers having fibers from natural and/or synthetic sources, and one or more mineral-containing layers. The mineral-containing layer(s) comprises a thermoplastic bonding agent fixing the mineral particles in place. The fiber-containing layer(s) and mineral-containing layer(s) can be shaped, sized, and manufactured such that the composite structure formed therefrom is capable of being machined to form the storage article. The composite structure can be repulped and recycled without the use of dispersions, emulsions, or aqueous solutions. Further, the composite reduces layer mass requirements for heat seal, barrier, and fiber adhesion compared to polymer layers. The composite structure further has tensile strength and other structural characteristics that allow it to be readily machined into desired storage article forms.
1. A method of making recyclable composite packaging structure including a fiber-containing layer and a mineral-containing layer, the method comprising:
extrusion coating the mineral-containing layer onto the fiber-containing layer using a bonding agent, wherein the mineral-containing resin has a density of 1.01 g/cm 3 to 4.90 g/cm 3 and a mineral content of 20% to 70%, the extrusion coating providing a moisture barrier having Tappi T464 moisture barrier values from about 0.46 g/100 in 2 to about 37.7 g/100 in 2 ;
wherein the extrusion process is carried out under the following conditions:
the resin having a melt flow index from 4 g/10 min. to 16 g/10 min.;
a melt temperature from 440° F. to 640° F.;
an extruder screw or tube barrel pressure from 1,200 psi to 2,500 psi;
an air gap from 4″ to 16″;
a die gap from 0.020″ to 0.050″;
barrel and die zone temperatures from 400° F. to 640° F.;
an extrusion line speed from 100 FPM to 3,500 FPM; and
an extrusion lamination line speed from 100 FPM to 3,500 FPM.
2. The method of claim 1 , wherein the mineral-containing resin is supplied to the extrusion process in the form of pellets.
3. The method of claim 1 , wherein the mineral-containing layer is applied to the fiber-containing layer in coat weights from 4 lbs/3 msf to 30 lbs/3 msf.
4. The method of claim 1 , wherein the recyclable composite packaging structure does not contain water-based dispersions, aqueous dispersions, aqueous coatings, emulsions, emulsion-containing coatings, water-containing dispersions, press-line applications, or off-line mixing processes.
5. The method of claim 1 , wherein the mineral-containing layer, weighing from 15 g/m 2 to 50 g/m 2 , is coextruded in line on an extrusion coating machine and bonded by extrusion to the fiber-containing layer.
6. The method of claim 1 , wherein the mineral-containing layer has a density from 1.33 g/cm 3 to 1.41 g/cm 3 .
7. The method of claim 1 , wherein the mineral-containing layer is from 35% to about 75% amorphous has a water vapor transmission rate (WVTR) under conditions of 100° F. and 90% relative humidity from 5 g/m 2 per day to 22 g/m 2 per day as determined using TAPPI Test Method T-64.