A biobased binder of carboxymethyl cellulose, citric acid, chitosan and wheat gluten for nonwoven and paper

The amount of disposable nonwovens used today for different purposes have an impact on the plastic waste streams which is built up from several single-use products. A particular problem comes from nonwoven products with "hidden" plastic (such as cellulose mixed with synthetic fibers and/or plastic binders) where the consumers cannot see or expect plastic. We have here developed a sustainable binder based on natural components; wheat gluten (WG) and a polyelectrolyte complex (PEC) made from chitosan, carboxymethyl cellulose and citric acid which can be used with cellulosic fibers, creating a fully biobased nonwoven product. The binder formed a stable dispersion that improved the mechanical properties of a model nonwoven. With WG added, both the dry and the wet strength of the impregnated nonwoven increased. In dry-state, PEC increased the tensile index with >30 % (from 22.5 to 30 Nm/g), and with WG, with 60 % (to 36 Nm/g). The corresponding increase in the wet strength was 250 % (from 8 to 28 Nm/g) and 300 % (to 32 Nm/g). The increased strength was explained as an enrichment of covalent bonds (ester and amide bonds) established during curing at 170 degrees C, confirmed by DNP NMR and infrared spectroscopy.