Physical and Mechanical Properties of Hydroxypropyl Methylcellulose-Coated Paper as Affected by Coating Weight and Coating Composition

Hydroxypropyl methylcellulose (HPMC)-coated papers without plasticizer and plasticized with polyols were prepared, and the effects of coating weight, different plasticizers (glycerol (GLY), sorbitol (SOR), and polyethylene glycol (PEG)), and plasticizer contents (20% to 50%) on the physical and mechanical properties of the resulting biopolymer-coated papers were studied. Coating weight was the most important factor affecting mechanical properties. Conversely, increasing coating weight led to a decrease in gloss and to an increase in tensile strength (TS), elongation at break (%E), and tearing resistance of coated papers. The application of unplasticized HPMC coatings (3 g/m(2)) on paper reduced water vapor permeability (WVP) and water absorption capacity by 25% as compared with uncoated paper. All plasticizers significantly (p < 0.05) increased WVP and Cobb(60) values of the films. With the exception of PEG, no effect was found with plasticizers on TS and %E of coated papers compared with those without plasticizer. HPMC-coated papers with PEG as a plasticizer showed significantly lower TS and higher %E and tearing resistance than the other plasticized films (p < 0.05). HPMC coating improved tensile properties and tearing resistance of paper and could be regarded as a reinforcement layer.