Thin-film sheet including cellulose fine-fiber layer

Abstract

The present invention provides a thin-film sheet configured from a single layer or a plurality of layers less than or equal to three layers including at least a cellulose fine-fiber layer that includes regenerated cellulose fine fibers by 50 wt % or more, wherein the thin-film sheet achieves improvements in both thermal stability (thermal coefficient of linear expansion and retention of elasticity at high temperature) and sheet strength, and is characterized in that the requirements: (1) the specific surface area equivalent fiber diameter of fibers constituting the cellulose fine-fiber layer is 0.20-2.0 μm inclusive; (2) the air impermeability is 1-100,000 s/100 ml inclusive; and (3) the sheet thickness is 2-22 μm inclusive are satisfied. The present invention also provides a composite sheet, a composite prepreg sheet, a separator for power storage devices, etc., that include the thin-film sheet.

Dependencies are inferred from the claim text.