From: Gary Jones(email@example.com )
Date: Tue, 10 Jul 2001 17:20:07
There are some misconceptions regarding the recycling of printed matter that has either been printed with UV cured inks or coated with UV cured coatings. These types of printed products have always been recyclable if a lower grade paper such as board for folding paper boxes, corrugated containers, or tissue paper was to be made. I classify this type of recycling as "downcycling". The problem with UV cured printed matter lies in the manufacturing of paper that is equal or better in grade than the paper being recycled or "upcycled".
In recent years, there has been a dramatic improvement in "upcycling" paper printed with UV cured inks or coatings. This is due to the progress made by paper companies in adopting new technology for recycling paper. Back in the early 1990's, the most common recycling technology used was washing and screening. UV cured materials were not easily "upcycled" with this approach. With the introduction of floatation cells into the recycling process, UV cured materials could be "upcycled" more easily.
As paper companies have upgraded existing plants and built new ones in response to the demand for recycled paper, floatation has become more popular and the problem with UV cured printed matter has diminished quite dramatically.
Essentially, floatation cells are used to bubble air through the repulped and screened fiber. Large particles such as formed from repulping UV cured materials adhering to the fiber are carried to the surface of the pulp and are removed. While it does take more energy to repulp UV cured printed or coated materials, this does not prohibit their ability to be recycled. Economic factors also play a role in recycling paper as uncoated paper tends to be more in demand than coated paper since there is more harvestable fiber per ton of paper, but in order for the floatation cells to be effective, they require a certain amount of clay or other inert to work properly. The clay content can either be added or it can be supplied through using coated paper, which has increased the demand for coated papers.
It is interesting that this was never an issue in Europe where flotation was adopted before it became popular in the US. Conversely, paper printed via water-based flexography is not readily recyclable with floatation technology. The paper companies are working to improve this, but to the best of my knowledge, it has not been resolved.