Abstract: Described herein are ink compositions that will not contaminate recycled plastic materials that come in contact with the inks; labels printed with such inks; and plastic articles having labels printed with such inks; and methods for printing with such inks, and recycled plastic material, such as recycled PET, that has little to no contamination from such inks. For example, during recycling, plastic containers that have been labelled with such inks are subjected to hot caustic wash solutions that cause the ink to separate the labels, When the inks described herein are removed from the label, they form a solid or precipitate, as opposed to dissolving in the hot caustic wash solution. The solid or precipitate is easily separated from the recycled plastic and wash solution, such as by filtration. The separated ink does not contaminate or stain the recycled plastic, or does so to a degree that is tolerable.

Abstract: The present invention provides a two part ink or coating system, wherein Part A comprises one or more hydroxyl functional resins, one or more aminoplast crosslinkers, one or more polyester polyols, and one or more solvents; and Part B comprises an acid catalyst. Part A and Part B are combined just prior to application on a substrate. The ink or coating system of the invention is resistant to removal from polyolefin film substrates when subjected to a hot caustic wash. When applied as an overcoat (backing coat) over conventional inks printed on polyolefin film substrates, the ink or coating system of the invention also prevents removal of the conventional inks from the polyolefin substrate when subjected to a hot caustic wash. Advantageously, use of the ink and coating systems of the present invention reduces ink staining and contamination of recycled PET flakes.