Date of Award

12-2013

Degree Name

Doctor of Philosophy

Department

Paper Engineering, Chemical Engineering and Imaging

First Advisor

Dr. Paul D. Fleming III

Second Advisor

Dr. Margaret Joyce

Third Advisor

Dr. John Cameron

Fourth Advisor

Dr. Hou T. Ng

Keywords

Deinking, water based ink, flexography, recycling, inkjet, flotation

Abstract

The use of water-based inks is on the rise. Sub-micron pigment particles are used for flexographic and inkjet water-based inks. Conventional deinking eliminates larger particles than those from these new ink systems. Therefore, water-based inks represent recycling difficulty.

Deinking experiments of water-based inks are carried out. The deinking strategy initially investigated elimination of pressure sensitive adhesive due to similar acrylic polymer chemistry used in water based inks. The impact of pH on stickies and ink agglomeration during deinking is studied. Experiments in acidic regions show growth of acrylic inks and stickies agglomerates, simplifying elimination.

Pre-recycling of water-based inks is explored. Exceptional cleanliness of acidic circuit waters compared to alkaline is demonstrated.

Conventional wisdom claims an alkaline environment is needed for ink detachment from paper. It is found that the benefit of acidic milieu is the agglomeration of the pigment – resin complex of water-based ink. Further, flotation deinking of model inks is performed. Agglomeration and flotation of inkjet inks using surfactants is performed to better understand ink behavior during deinking while limiting its redeposition. Three types of food grade soybean oils are tested for utilization in the paper recycling industry. Fatty acids extracted from oils are utilized in one loop flotation deinking of offset printed paper. Extracted fatty acids “A”, “B” and “C” had varied acid and saponification number. The effect of each of the soy-oil fatty acid on deinking is studied. Deinking results are compared to INGEDE 11p procedure, using oleic acid. It is discovered that fatty acids “C” and “B” have better deinking performance than oleic acid. Lower acid number acids perform better.

Acid “C” and bentonite clay is used in one loop - flotation deinking of inkjet printed-paper. Fatty acid “C” is compared against oleic acid. It is determined that fatty acid “C” has positive effects on deinkability.

The surface of the bentonite clay is altered by coating it with fatty acid “C”. Bentonite clay is successful in removing sub-micron hydrophilic inkjet ink pigment particles. Clay has a positive effect on the discoloration of recycled water.

Access Setting

Dissertation-Open Access

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