Mitigation of mineral oil migration in pressure-sensitive labels and films
Disclosed are hot-melt, curl-free methods, structures, and compositions, which in flexible packaging applications, reduce mineral-oil, hydrocarbon migration into packaged food. One embodiment provides an optionally oriented base film having a first side and a second side that is a transparent or opaque film. Further, the composition comprises, consists essentially of, or consists of a water-based primer applied to the first side. Further still, the composition includes a barrier layer to mineral-oil migration, wherein the barrier layer is located between the adhesive-receptive layer and the polymeric substrate, and wherein the barrier layer consists essentially of: (i) polymers of polyvinyl alcohol, ethylene vinyl alcohol, polyester, polyamide, or combinations thereof; and (ii) optionally additives. The barrier layer provides a barrier to mineral-oil migration of 0.1 μg/day*dm 2 or less at 40° C. for 40 days, and the curl-resistant composition does not curl when heated for at least one hour at 60° C.
1. A curl-resistant composition comprising:
a polymeric substrate having a first side and a second side;
a printable coating layer on the first side;
an adhesive-receptive coating layer on the second side, wherein the adhesive-receptive coating layer comprises acrylic polymer; and
a barrier layer to mineral-oil migration, wherein the barrier layer is located directly between and on the adhesive-receptive coating layer and the polymeric substrate, and wherein the barrier layer consists essentially of: (i) polymers of polyvinyl alcohol, ethylene vinyl alcohol, polyester, polyamide, or combinations thereof; and (ii) optionally additives;
wherein there is no adhesive transfer between a glass or metal plate and the adhesive-receptive coating layer when peeling the curl-resistant composition from the glass or metal plate at 180 degrees at 24 hours from adhesion at a peeling speed of 300 mm/min and peel strength at or below 1450 g/25 mm regardless of whether the adhesive-receptive coating layer is water-based or solvent-based;
wherein the barrier layer provides a barrier to mineral-oil migration of 0.1 μg/day*dm 2 or less at 40° C. for 40 days, and
wherein the curl-resistant composition does not curl when heated for at least one hour at 60° C.
2. The curl-resistant composition of claim 1 , where the barrier layer is a coextruded layer.
3. The curl-resistant composition of claim 1 , wherein the polymeric substrate is biaxially oriented.
4. The curl-resistant composition of claim 1 , wherein the polymeric substrate comprises polypropylene.
5. The curl-resistant composition of claim 1 , further comprising additives.
6. The curl-resistant composition of claim 1 , wherein the adhesive-receptive coating layer is water-based.
7. The curl-resistant composition of claim 1 , wherein the adhesive-receptive coating layer is solvent-based.
8. The curl-resistant composition of claim 1 , wherein the adhesive-receptive coating layer is a hot-melt adhesive composition.
9. The curl-resistant composition of claim 1 , wherein the peel strength is at least 700 g/25 mm.
10. The curl-resistant composition of claim 1 , wherein the barrier layer is a dispersion.
11. The curl-resistant composition of claim 1 , wherein the barrier layer is a solution.
12. The curl-resistant composition of claim 1 , wherein the barrier layer consists essentially of: (i) polymers of polyvinyl alcohol, ethylene vinyl alcohol, or combinations thereof; and (ii) optionally additives.
13. The curl-resistant composition of claim 1 , wherein the adhesive-receptive coating layer further comprises ethylene polymer.
14. The curl-resistant composition of claim 1 , where the barrier layer is a primer.
15. The curl-resistant composition of claim 14 , wherein the primer is water-based.
16. The curl-resistant composition of claim 14 , wherein the primer is solvent-based.
17. The curl-resistant composition of claim 1 , further comprising a second primer layer between the polymeric substrate and the printable coating layer.
18. The curl-resistant composition of claim 17 , wherein the second primer layer has a same composition as the barrier layer.
19. The curl-resistant composition of claim 17 , wherein the second primer layer has a different composition as the barrier layer.