Effect of NaOH/urea solution on enhancing grease resistance and strength of paper

Abstract A new way as shown in the following scheme was developed to fabricate paper with high strength and grease resistance. Filter paper was impregnated in NaOH/urea aqueous solution pre-cooled to -12°C for 30 s and incubated at a fixed temperature for a period of time. Swelling and dissolution of cellulose fibers facilitated more compact structure of paper and higher strength. Various influencing factors were investigated in an attempt to improve grease resistance of the paper. The results demonstrated that the paper after treatment showed a 100% grease barrier property within 24 h, and a double increase in both tensile strength and tear strength compared with the untreated paper. Moreover, burst strength was enhanced more than three times and the stretch was improved simultaneously when the paper was performed with NaOH/urea (7%:12% weight ratio) at -12°C for 120 min. In addition, the wet tensile strength of the treated paper was close to the dry tensile strength of the untreated paper.