An effect of carboxymethyl starch addition on adhesion to paper of water-soluble pressure-sensitive adhesive

A novel pressure-sensitive adhesive containing carboxymethyl starch (CMS) with various degrees of substitution, has been developed for the paper industry. Obtained adhesives were transferred onto water-dispersible paper carrier giving repulpable double-sided splicing tape. The effect of carboxymethyl starch degree of substitution (DS) on essential adhesive properties: tack, peel adhesion, as well as shear strength for steel and various papers have been tested. Additionally, the solubility in water and alkaline medium has been evaluated. The highest tack and peel adhesion increase was reported for PSA containing CMS with degree of substitution DS 0.86, to fax paper. Moreover, the dynamic shear strength test, imitating the shear conditions in paper processing revealed, that the highest values of this parameter exhibited the system with 15 wt% CMS DS 0.86. For this system, the shortest water-dissolving times as well as at elevated pH were noted: 314 s and 60 s, respectively. The best performance exhibited the adhesive prepared from the mixture of acrylic monomers (35 wt% 2-ethylhyexyl acrylate, 30 wt% butyl acrylate and 35 wt% acrylic acid), 0.4 wt% aluminum acetyl acetonate (crosslinking agent), 50 wt% poly(ethylene glycol) as plasticizer, and 15 wt% CMS with DS 0.86 (basing on acrylic polymer content).