Method of manufacturing of low-odor packaging materials
The present invention provides a method for producing a low-odor, printed packaging material and the printed packaging material produced thereby. The printed packaging material of the present invention is especially suitable for packaging of substances, such as food, drugs and tobacco, which require low odor from printing inks. In this process, the printed ink is activated by exposure to actinic radiation, such as UV light, before an actinic-radiation curable coating is applied thereto. The exposure of the printed ink to UV light reduces residual solvent content and odor of the packaging material and improves the friction resistance and gloss of the printed images. Furthermore, the exposure of the printed packaging material to UV light provides an additional benefit of reducing microbial count, thereby extending a shelf-life of the packaged substance, such as food and drugs.
1. A method of producing a printed packaging material comprising, in sequence:
applying an actinic radiation activatable liquid ink to a packaging material;
exposing the ink to first actinic radiation;
applying an energy-curable coating over the ink; and
curing the coating with second actinic radiation;
wherein the ink is substantially free of curable functionality,
wherein the exposure to the first actinic radiation and curing with the second actinic radiation is such that the packaging material contains less than 700 ppm total of residual solvent or water, and
wherein the exposure to the first actinic radiation and curing with the second actinic radiation is such that the packaging material has a degree of cure of at least 5 MEK rubs.
2. The method of claim 1 , wherein the packaging material is a thermoplastic flexible film, and wherein a to-be-packaged substance is enclosed within the plastic film subsequent to the actinic radiation curing thereof.
3. The method of claim 1 , wherein the packaging material is a foil laminate paper or paper plastic laminate, and wherein a to-be-packaged substance is enclosed within the plastic film subsequent to the actinic radiation curing thereof.
4. The method of claim 1 , wherein the first actinic radiation is UV light.
5. The method of claim 1 , wherein the second actinic radiation is an electron beam.
6. The method of claim 1 , wherein the second actinic radiation is UV light.
7. The method of claim 1 , wherein the energy-curable coating is free of pigment.
8. The method of claim 1 , wherein the liquid ink is applied more than once.
9. The method of claim 1 , wherein the liquid ink is solvent-based.
10. The method of claim 1 , wherein the liquid ink is water-based.
11. A method of producing a printed packaging material comprising, in sequence:
applying an actinic radiation activatable liquid ink to a packaging material;
exposing the ink to first actinic radiation;
applying an energy-curable coating over the ink; and
curing the coating with second actinic radiation;
wherein the ink is substantially free of curable functionality, and
wherein the actinic radiation activatable liquid ink is photoinitiator-free and the first actinic radiation is UV light, and wherein the exposure to the first actinic radiation and curing with the second actinic radiation is such that the packaging material contains less than 500 ppm total of residual solvent or water and a degree of cure of at least 20 MEK rubs.
12. The method of claim 11 , wherein the packaging material is a thermoplastic flexible film, and wherein a to-be-packaged substance is enclosed within the plastic film subsequent to the actinic radiation curing thereof.
13. The method of claim 11 , wherein the packaging material is a foil laminate paper or paper plastic laminate, and wherein a to-be-packaged substance is enclosed within the plastic film subsequent to the actinic radiation curing thereof.
14. The method of claim 11 , wherein the first actinic radiation is UV light.
15. The method of claim 11 , wherein the second actinic radiation is an electron beam.
16. The method of claim 11 , wherein the second actinic radiation is UV light.
17. The method of claim 11 , wherein the energy-curable coating is free of pigment.
18. The method of claim 11 , wherein the liquid ink is applied more than once.
19. The method of claim 11 , wherein the liquid ink is solvent-based.
20. The method of claim 11 , wherein the liquid ink is water-based.