Improving the extensibility of paper: Sequential spray addition of gelatine and agar

Research has been undertaken to determine whether gelatine and agar can be used together and whether they have an additive action for improved paper extensibility and formability. The mechanical properties of paper were evaluated and adsorption phenomena were investigated, together with the effect of crosslinker addition to polymer solutions on the properties of the treated paper. Polymer solutions were prepared and the crosslinker added approximately 30s before spraying. It has been demonstrated that sequential application was only effective if gelatine was added first followed by agar. While gelatine easily penetrated in the z-direction and adsorbed on cellulose, agar formed a film on the surface. Adsorption studied showed that agar retention was significantly improved upon gelatine pre-adsorption. Analysis of paper treated with gelatine and agar revealed inter-mixing of the polymers, although an agar film was still formed. Crosslinker addition to the solution further improved extensibility and tensile strength of papers. In addition, formability of paper treated with gelatine and agar enabled production of tray-like, three-dimensional shapes with 2-3cm in depth.