| 摘要 |
A substantially non-curling gummed sheet of the water-remoistenable type is made by dissolving water-reactivatable gum in water to form a water solution of gum, dissolving in a solvent a binder which is substantially insoluble in water, dispersing dry particles of water-activatable gum in the binder solution, the dry particles of gum being not readily soluble in the solvent and the binder solution being incompletely miscible with the water solution, dispersing the water solution in the binder solution to form an emulsion comprising globules of water solution of gum in addition to the particles, coating the emulsion on a sheet, and drying the coating while permitting the globules to coalesce partially to form a honeycomb structure of partially coalesced pieces of gum, the binder preventing the pieces coalescing completely. After the water solution is dispersed in the binder solution and before the coating is dried, the particles absorb water from the water solution and the particles partially coalesce when the coating dries. The binder may be resinous and the ratio of gum to binder may be at least 10 : 1 by weight, e.g. of the order of 30 : 1. The binder solvent may comprise at least 25% of the liquid by volume in the emulsion. The binder solvent may be a mixture including a substantially water-immiscible solvent and a solvent having a limited miscibility with water. The binder may be selected from vinyl ester copolymer, polyvinyl chloride, butadiene-styrene copolymers and polymers of acrylic esters, e.g. vinyl acetate copolymerized with a small proportion of crotonic acid. |
