| 摘要 |
PROBLEM TO BE SOLVED: To provide paper to be used as a packing material for a beverage or food stuff, or other industrial materials, and specifically, to provide waterproof paper having excellent waterproofness under a condition of being exposed to hot water or warm water.SOLUTION: Waterproof paper includes: a cellulose fiber having a carboxy group; and a polyvalent metal compound. The cellulose fiber and a polyvalent metal ion derived from the polyvalent metal compound form an ion cross-linkage. The contents of the carboxy group and an aldehyde group are 0.5 mmol or more to 5.0 mmol or less, and 0.1 mmol or less, respectively, in 1 g of the cellulose fiber.SELECTED DRAWING: None |
