Recyclability of surface-sized grades
13 November 2009
Background
Pira has long been active in the development of surface sizing formulations for improved image quality for uncoated woodfree papers. The question is how to demonstrate that the surface treatments did not impair the recyclability of the treated papers? For certain surface-treated digital and security print products it was necessary to show that ink could be removed by a wash deinking stage as the inks could not be removed by conventional flotation deinking.
Methods
The challenge was to emulate a multi-cycle wash process by a simple laboratory method. Ideally, the method had to avoid the entrapment of ink particles within a filter layer, so washing in a filter funnel was not a realistic option. Instead, we developed a method based on the Britt Dynamic Drainage Jar (DDJ) in which the fibre suspension could be repeatedly washed without the formation of a filter map.
Outcome
By a simple adaptation of a common paper laboratory method, we were able to prove that the surface-treated papers could be deinked to bright, white pulps to the satisfaction of our clients and their customers.
See Also
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