Preparation of Water-Repellent and Flame-Retardant Coating on Mulberry Paper

A mulberry paper has been used to produce many consumer products such as lantern, card, packaging and decorating articles. Similar to other cellulosic materials, the mulberry paper bears abundant hydroxyl groups on its surface. Besides easily ignited, it can absorb water or humidity. To improve its thermal stability and to reduce deterioration caused by moisture adsorption, the mulberry paper was coated with a flame-retardant substance which was monoammonium phosphate (MAP) and a hydrophobic substance which was poly(methylhydrogen siloxane) (PMHS). The coating was conducted by immersing the mulberry paper in coating solution for 2 min followed by drying at 50 degrees C for 30 min. By varying a weight ratio of the PMHS and MAP, the PMHS:MAP weight ratio of 10:10 was found to be the optimum coating solution. The coated mulberry paper had good thermal property according to the thermogravimetric analysis. The uncoated mulberry paper showed residue of about 21% while the coated mulberry paper showed the increased residue of more than 50%. The burning test revealed that the coated mulberry paper was self-extinguished after removal of the ignition source while complete burning was observed on the uncoated paper. Moreover, it was water repellent with a water contact angle of 101.48 +/- 5.81 degrees.