Preparation of environmentally friendly hydrophobic paper by coating method

Abstract Non-Newtonian viscous fluids such as yogurt, honey, etc., due to their extremely high viscosity and complex fluidity, remain on food containers after use, where adhesion and staining occurs, which is a great inconvenience and causes a lot of wasted resources. Hydrophobic coatings can be an excellent candidate for eliminating liquid waste. Inexpensive wollastonite nanoparticles were used to build rough micro- and nano-structures, and chitosan was used to emulsify rice bran wax to prepare green and low surface energy emulsions. The above two were mechanically mixed to obtain the hydrophobic emulsion, and coated on the paper surface and heat-treated to prepare the hydrophobic paper. Contact angles up to 157.3°. The coating exhibits good self-cleaning properties for a wide range of non-Newtonian viscous food liquids and shows excellent resistance to repeated machine bending and multiple abrasion damages, while maintaining its hydrophobicity. After 40 cycles of friction, the contact angle is 148.1°, which is still close to 150° and has good hydrophobicity. In addition, the coating has great potential for application to the interior surfaces of various food packages to reduce or even eliminate liquid food residues.