Bio-based PEC compositions as binders for fiber based materials, textiles, woven and nonwoven materials

Method of treating materials, said materials comprising fiber based materials, textiles, woven and nonwoven materials, to increase said materials' dry strength and/or wet strength, the method comprising applying a bio-based polyelectrolyte complex (PEC) composition suitable as a binder, wherein the PEC composition comprises a cationic biopolymer, an anionic biopolymer, an acid and a preservative, and wherein

• the net charge of the PEC is cationic,
• the charge ratio of the anionic biopolymer and the cationic biopolymer is <1,
• the cationic biopolymer is chitosan, wherein the concentration of cationic biopolymer is 0.005-30% and the chitosan has a degree of deacetylation of 66-100%,
• the anionic biopolymer is polyanions derived from nature
• the acid is a Brønsted acid and/or a Lewis acid, wherein the Brønsted acid is selected from any organic and/or inorganic acids, wherein the Lewis acid is selected from any cationic mono- or multivalent atom, and wherein the concentration of the acid is 0.01-30 wt %,
• the weight ratio between cationic biopolymer and anionic biopolymer is 1:0.1 to 1:20,
• the weight ratio between cationic biopolymer and acid is 1:0.1 to 1:30;
• and
• the pH is less than 7
• wherein the PEC composition comprises water selected from tap water, distilled water and/or deionized water, and at least 0.05 wt % of a water soluble plasticizer, selected from one or more of polyols or monosaccharides.