Peelable composite thermoplastic sealants in packaging films
A peelable sealing structure includes a sealing layer and one or more optional additional layers. The peelable sealing structure includes a sealing surface that is formable into a peelable seal upon contact with a sealing substrate at all temperatures in a peelable seal temperature range. Moreover, the peelable sealing structure comprises a thermoplastic polymer and an additive dispersed within at least a portion of the thermoplastic polymer with the peelable sealing structure defining the sealing surface.
1. A packaging system having a peelable seal section and a container section, the peelable seal section including a first sealing layer and a second sealing layer such that the first sealing layer contacts the second sealing layer to form a peelable seal, the first sealing layer including:
a thermoplastic polymer; and
an organoclay dispersed within the thermoplastic polymer, wherein the first sealing layer has a seal initiation temperature from about 170° F. to about 350° F. and a tensile modulus from about 500 to about 2000 MPa, the organoclay comprising platelets having an average separation between 20 and 45 angstroms.
2. The packaging system of claim 1 wherein the first sealing layer has a sealing surface having a roughness average from about 1500 to about 5000 angstroms.
3. The packaging system of claim 1 wherein the first and second sealing layers are formable into the peelable seal at all temperatures within a peelable seal temperature range, the peelable seal temperature range being from the seal initiation temperature to a temperature that is at least 100° F. above the seal initiation temperature.
4. The packaging system of claim 1 wherein the organoclay comprises a plurality of particles having a spatial dimension less than 200 nm.
5. The packaging system of claim 1 wherein the platelets have an average separation of at least 30 angstroms.
6. The packaging system of claim 1 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof.
7. The packaging system of claim 1 wherein the organoclay is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay.
8. The packaging system of claim 1 wherein the organoclay is present in an amount from 2 wt % to 10 wt % of the combined weight of the thermoplastic polymer and the organoclay.
9. The packaging system of claim 1 wherein the thermoplastic polymer further comprises a component selected from the group consisting of nylons, polyolefins, polystyrenes, polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, ethylene vinyl acetate, and mixtures thereof.
10. The packaging system of claim 1 wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof.
11. The packaging system of claim 1 wherein the thermoplastic polymer comprises ethylene vinyl acetate.
12. The packaging system of claim 1 wherein the second sealing layer also includes:
the thermoplastic polymer; and
the organoclay.
13. A multilayer sealing structure comprising:
a sealing layer including a thermoplastic polymer and an organoclay dispersed within the thermoplastic polymer, the sealing layer having a seal initiation temperature from about 170° F. to about 350° F. and a tensile modulus from about 500 to about 2000 MPa, the organoclay comprising platelets having an average separation between 20 and 45 angstroms; and
a first additional layer disposed on the sealing layer.
14. The multilayer sealing structure of claim 13 further comprising a second additional layer disposed on the first additional layer.
15. The multilayer sealing structure of claim 13 wherein the sealing layer is formable into a peelable seal at all temperatures within a peelable seal temperature range, the peelable seal temperature range being from the seal initiation temperature to a temperature that is at least 100° F. above the seal initiation temperature.
16. The multilayer sealing structure of claim 13 wherein the organoclay comprises a plurality of particles having a spatial dimension less than 200 nm.
17. The multilayer sealing structure of claim 13 wherein the platelets have an average separation of at least 30 angstroms.
18. The multilayer sealing structure of claim 13 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof.
19. The multilayer sealing structure of claim 13 wherein the organoclay is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay.
20. The multilayer sealing structure of claim 13 wherein the thermoplastic polymer further comprises a component selected from the group consisting of nylons, polyolefins, polystyrenes, polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, ethylene vinyl acetate, and mixtures thereof.
21. The multilayer sealing structure of claim 13 wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof.