Patent ID: 11866886

Abstract:
A biodegradable food-grade polyvinyl alcohol (PVA) paper substrate and a method for making the same are provided. The method includes: providing a paper substrate; preparing a first coating material by rendering PVA with a degree of alkalization of 90%-100% and a molecular weight of 100,000-300,000 into an aqueous solution in which the PVA has a weight ratio of 3%-15%; preparing a second coating material by rendering sodium trimetaphosphate into an aqueous solution in which the sodium trimetaphosphate has a molar concentration of 0.05-1 Mol/l; forming a coating layer on a surface of the paper substrate; forming a surface cross-linked layer on the coating layer; and drying. The resulting PVA paper substrate is biodegradable, of food-grade quality, and resistant to water and grease, with a grease resistance higher than or equal to that corresponding to kit No. 6 in a TAPPI T559 pm-96 standard test.