engleski

Thermochromic flexografic prints in paper recycling process

The production of recycled paper consumes less energy (between 28 and 70%), reduces carbon dioxide emissions and the amount and pollution of wastewater compared to the production of paper from virgin fibers. Paper collected for recycling contains cellulose fibers that must be separated from various impurities such as inks, varnishes, coatings, laminates, staples, etc. All of these impurities can have a negative impact on the papermaking process and must be removed to maintain the quality of the recycled paper. Ink removal is the most important process in the production of recycled paper. It depends on the quality of the collected paper for recycling, the type of printing technique, properties of the printing inks, the age of the product and the climatic conditions during its life cycle, as well as the conditions in the deinking itself (the chemicals used). The extraction of printing ink from paper suspension can be carried out by different procedures, with flotation as the most common one. In addition to flotation deinking, research has shown that adsorption deinking can effectively remove printing ink from pulp suspension. The research carried out in this paper describes the possibility of recycling thermochromic flexographic prints. The sample was recycled using different methods to determine the most effective method. Based on the results, it can be concluded that samples printed with thermochromic printing ink are problematic to recycle. Comparison of the optical parameter results shows that the deinking chemicals used, as well as the addition of polymer granules, do not significantly improve the optical properties of the recycled papers. Adsorption deinking with polypropylene as adsorbent and the chemicals used in INGEDE 11 method did not significantly affect the results. The conclusion of this paper is that new methods of recycling thermochromic prints should be further researched, as well as researching new deinking chemicals, optimizing them, and introducing new polymer materials as adsorbents in adsorption deinking, which has proven to be an effective method for recycling digital prints.

thermochromic inks, flexographic printing, recycling

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