Repulpable and recyclable composite packaging articles and related methods
A reusable, fiber containing pulp product is described that is highly suited for use in the manufacture of paper products. The reusable, fiber containing pulp product provides a mixture of fibers and small, dense polymer/particle fragments. The polymer/particle fragments within the reusable, fiber containing pulp product have a size range and density that facilitates efficient removal of the polymer/particle fragments using pressure screens.
1. A method of manufacturing a heat sealable and recyclable packaging structure, the method comprising:
extrusion coating released fibers with a plurality of polymer/particle fragments comprising a thermoplastic and particles, wherein the plurality of polymer/particle fragments have a mean surface area of 0.0005 mm 2 to 2 mm 2 and a density of 1.01 g/cm 3 to 4.75 g/cm 3
wherein the extrusion process is carried out under the following conditions:
the polymer/particle fragments resin having a melt flow index from 4 g/10 min to 16 g/10 min;
a melt temperature from 590° F.±20%;
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.; and
an extrusion lamination line speed from 100 FPM to 3,500 FPM.
2. The method of claim 1 , wherein the polymer/particle fragments have a mean surface area of from 0.01 mm 2 to 2 mm 2 .
3. The method of claim 1 , wherein the particles of the polymer/particle fragments have a hardness of between 2.0 to 4.0 Mohs and an average surface area of from 1.0 m 2 /g to 1.3 m 2 /g.
4. The method of claim 1 , wherein the particles of the polymer/particle fragments have a hardness of between 2.0 to 4.0 Mohs and an average surface area of from 1.8 m 2 to 2.3 m 2 .
5. The method of claim 1 , wherein the particles of the polymer/particle fragments comprise mineral particles, and wherein the mineral particles are selected from the group consisting of clay, kaolin, CaCO 3 , mica, and silica.
6. The method of claim 5 , wherein the mineral particles have a mean diameter of from 4 μm to 14 μm.
7. The method of claim 1 , wherein from 35% to 99% of the polymer/particle fragments have a mean surface area of 0.0005 mm 2 to 2 mm 2 and a density of 1.01 g/cm 3 to 4.75 g/cm 3 .
8. The method of claim 1 , wherein the released fibers comprise reusable fiber containing pulp that are suitable for manufacture of new paper products.
9. The method of claim 1 , wherein the released fibers comprise softwood fibers, hardwood fibers, or a mixture of softwood and hardwood fibers.
10. The method of claim 9 , wherein the mixture of softwood and hardwood fibers comprises from 5% to 95% softwood fibers.
11. The method of claim 9 , wherein the mixture of softwood and hardwood fibers comprises from 25% to 90% softwood fibers.
12. The method of claim 9 , wherein the mixture of softwood and hardwood fibers comprises from 5% to 95% hardwood fibers.
13. The method of claim 9 , wherein the mixture of softwood and hardwood fibers comprises from 25% to 90% hardwood fibers.
14. The method of claim 1 , wherein the released fibers are derived from a paper having a basis weight of from 30 lbs/3000 sq. ft. to 200 lbs/3000 sq. ft. and a thickness of from 0.010 inches to 0.036 inches.
15. The method of claim 1 , wherein the polymer/particle fragments are dimensioned to pass through 0.005 inch round hole or slotted pressure screens.
16. The method of claim 1 , wherein the thermoplastic has a physical melt flow index of from 4 g/10 min to 16 g/10 min.