Coating of Lyocell Nonwovens by Carboxymethylated Starches for Production of Hydrogel‐Nonwoven Hygiene Tissues

The production of hydrogel‐nonwoven wet wipes, by a combination of carboxymethylated starch (CMS) gel on a lyocell nonwoven, on textile machinery has been investigated. This was done to produce wet wipes using industrial textile machinery and pre‐modified starches. CMS of a degree of substitution (Ds) of 0, 0.25 and 1 were coated in a concentration range of 1.5%–5%wt. onto the nonwoven. CMS was cross‐linked by 5% wt. citric acid and 2.5% wt. sodium phosphinate. CMS coating reduces the chemical oxygen demand (COD) of material release due to a gluing effect for 1.5% wt. CMS (by ∼ 30%), while it increases for higher concentrations possibly due to CMS elution. The gluing effect also translates into compaction and a steeper force curve upon compression. Citric acid released upon swelling is higher for a higher Ds and citric acid content (∼10%–30%). Water retention values (9 min at 250 g) of CMS‐nonwovens are increased compared to the untreated lyocell nonwoven for all Ds and concentrations by 30%–100%. Increasing CMS concentrations increase the elastic modulus of the hydrogel structure (1–5x). CMS‐nonwoven composite can be produced on common textile machinery using citric acid for crosslinking. This enables the industrial production of hydrogel‐nonwoven composites. However, due to the difference in nonwoven structure compared to industrial wet wipes no saving of material or chemicals from nonwoven substitution is encountered.