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 recyclable composite packaging structure, comprising:
a fiber-containing layer; and
a barrier layer bonded to the fiber-containing layer, the barrier layer including mineral particles evenly dispersed in a matrix of a polyolefin bonding agent;
wherein the barrier layer has a basis weight from about 4 lbs/3 msf to about 60 lbs/3 msf, a density from about 1.10 g/cm 3 to about 1.75 g/cm 3 , and a caliper from about 0.30 mil to about 3 mil.
2 . The recyclable composite packaging structure of claim 1 , wherein the barrier layer is extruded.
3 . The recyclable composite packaging structure of claim 1 , wherein the fiber-containing layer has a caliper from about 0.010″ to about 0.030″ and a basis weight from about 136 lbs/3 msf to about 286 lbs/3 msf.
4 . The recyclable composite packaging structure of claim 1 , wherein the barrier layer has a polyolefin content from about 30% to about 70% by weight.
5 . The recyclable composite packaging structure of claim 1 , comprising about 1% to about 40% inorganic matter.
6 . The recyclable composite packaging structure of claim 1 , comprising a total repulping recovery up to 98%.
7 . The recyclable composite packaging structure of claim 1 , wherein the mineral particles comprise diatomaceous earth with ultrafine nanoparticles having densities from about 2.4 g/cm 3 to about 4.9 g/cm 3 and particle sizes from about 100 nm to about 10 μm.
8 . The recyclable composite packaging structure of claim 1 , wherein the polyolefin bonding agent has molecular weights from about Mw 10,000 to about Mw 100,000 and a branching index (g′) from about 0.99 to about 0.65 as measured at the Z-average molecular weight (Mz) of the polymer.
9 . The recyclable composite packaging structure of claim 1 , wherein the polyolefin bonding agent has an isotactic run length from about 1 to about 40.
10 . The recyclable composite packaging structure of claim 1 , wherein the polyolefin bonding agent has a shear rate from about 1 to about 10,000 at temperatures from about 180° C. to about 410° C.
11 . The recyclable composite packaging structure of claim 1 , wherein the mineral particles are cube or block particles.
12 . The recyclable composite packaging structure of claim 1 , wherein the mineral particles have an average surface area from about 1-1.3 m 2 /g to about 1.8-2.3 m 2 /g.
13 . The recyclable composite packaging structure of claim 1 , wherein the mineral particles comprise calcium carbonate particles having from about 18%-80% particle diameters finer than 6 μm and from about 33%-96% particle diameters less than 10 μm and top cut from about d98 of 4-15 μm and a surface area from about 3.3 m 2 /g to about 10 m 2 /g, a surface treatment level from about 0.6% to about 1.5% by weight of treatment agent or about 99% by weight of the calcium carbonate.
14 . The recyclable composite packaging structure of claim 1 , wherein the fiber-containing layer comprises nano-cellulose having a crystalline content from about 40% to about 70%, including nano-fibrils, micro-fibrils, and non-fibril bundles having lateral dimensions from about 4 nm to about 30 nm and highly crystalline nano-whiskers from about 100 nm to about 1,000 nm, with fiber widths from about 3 nm to about 15 nm, having charge densities from about 0.5 meq/g to about 1.5 meq/g, and the nano-cellulose having a stiffness from about 140 GPa to about 220 GPa and a tensile strength from about 400 MPa to about 600 MPa.
15 . The recyclable composite packaging structure of claim 1 , wherein some of the mineral particles contain fatty acid and stearate coatings having a Hunter reflectance (green) from about 91% to about 97%, a Hunter reflectance (blue) from about 89% to about 96%, a Mohs hardness from about 2.75 to about 4.0, a particle pH in water, 5% slurry, at 23° C., from about 8.5 to about 10.5, a particle resistance in water, at 23° C., from about 5,000 ohms to about 25,000 ohms, an ASTM D1199 maximum percentage on a 325 mesh from about 0.05 to about 0.5, a volume resistivity at 20° C. of 10 9 to about 10 11 ohms, a standard heat of formation from its elements at 25° C. from about 288.45 to about 288.49 kg-cal/mole, a standard free energy of formation from its elements from about 269.53 to about 269.78 kg-cal/mole, a specific heat 1 g 1° C. (between 0° C. and 100° C.) from about 0.200 to about 0.214, a heat conductivity of about 0.0071 g-ca/sec/cm 2 /1 cm thick at 20° C., a coefficient of linear expansion C=9×10 −6 at 25° C. to 100° C. and C=11.7×10 at 25° C. to 100° C.
16 . The recyclable composite packaging structure of claim 1 , wherein the fiber-containing layer comprises vinyl and inorganic mineral coatings and fillers.
17 . The recyclable composite packaging structure of claim 1 , wherein the fiber-containing layer has a surface smoothness from about 1.50 to about 3.15, a smoothness from about 150 to about 200 Bekk-seconds, an ash content from about 1% to about 40% by weight, a static friction coefficient μ s from about 0.02 to about 0.50, and a cellulose content having thermal conductivity from about 0.034 to about 0.05 W/mk.
18 . The recyclable composite packaging structure of claim 1 , wherein some virgin and recycled fiber types within the fiber-containing layer include mechanical, thermo-mechanical, chemo-thermo-mechanical, and chemical having an average aspect ratio from about 5 to about 100, a softwood fiber thickness from about 1.5 mm to about 30 mm, a hardwood fiber thickness from about 0.5 mm to about 30 mm, a filled fiber content from about 1% to about 30%, a density from about 0.3 g/cm 3 to about 0.7 g/cm 3 , fiber diameters from about 16 μm to about 42 μm, a fiber coarseness from about 16 mg/100 m to about 42 mg/100 m, a permeability from about 0.1×10 15 m 2 to about 110×10 15 m 2 , a hydrogen ion concentration from about 4.5 to about 10, a Tappi 496, 402 tear strength from about 56 to about 250, a Tappi 414 tear resistance from about m49 to about m250, and a moisture content from about 2% to about 18% by weight.
19 . The recyclable composite packaging structure of claim 1 , wherein the fiber-containing layer comprises a combination of recycled fiber, virgin fiber, thermo-mechanical pulp “TMP,” virgin kraft fiber, clay coated craft fiber, clay coated unbleached kraft fiber, and solid bleached sulfate fiber.
20 . The recyclable composite packaging structure of claim 1 , wherein the barrier layer comprises Tappi T410 weights from about 5.5 g/m 2 to about 52.2 g/m 2 , Tappi T464 moisture barrier values from about 0.46 g/100 in 2 to about 37.7 g/100 in 2 , Tappi T441 Cobb 2-minute water absorption from about 0.00 to about 0.40, T441 30-minute water absorption from about 0.00 to about 0.45, and a Tappi T559 grease resistance of 12.0.