De-Foiling of Wasted Paper from Hot Foil Stamping for Paper Recycling

Abstract

The separation of the foil layer from the hot foil stamped paper was the main objective of this research. After de-foiling from wasted paper, the pulp was used to repulp to make a recycled paper, which the optical properties and printability of recycled paper were determined. Two colors of foil were used to prepare samples: silver foil (colorless) and pink foil (colored). They were hot-stamped onto 13 gsm  coated paper. There were three differences in the degree of foil printed area consisted of 25%, 50%, and 75% on 100 cm² paper area, respectively. Then, the printed paper was torn apart and immerse in water and acetone solution for de-foiling process to compare the de-foiling efficiency. The effect of the foil printed area was investigated. It was found that the number of foil dots (dirtiness) on recycled paper is very large. When recycled paper has a large foil area on the paper, especially, the foil area of 75% was the highest.  Comparison of the solution, it showed that acetone solution can dissolve the pink color from foiled paper more that water, which optical property was better. In terms of printability, it showed no differences between de-foiling recycled paper and recycled paper. Therefore, hot stamping foil paper can be recycled and provide usable paper quality. However, the foil area should be less than 50%, and an acetone solution should be used to help dissolving the foil color layer.