Patent ID: 8728616
Filing Date: 2014-05-20
Classification: B29C,B29K,C08J,Y10T

Abstract:
1. A polymer sheet, comprising: nanocrystals of a polymer in a proportion of not less than 80% of the polymer sheet, the polymer sheet satisfying the following conditions (I), (II), (III), and (IV), the polymer sheet being produced by (i) sandwiching polymer melt of a supercooled state between a pair of sandwiching rollers, (ii) elongating the polymer melt by rolling at an elongation strain rate not slower than a critical elongation strain rate, and (iii) crystallizing the polymer melt, and the polymer sheet being produced by setting a radius R of the sandwiching rollers, an average thickness L of the polymer sheet which has been subjected to the elongation by roiling, and a sheet take-off speed V at the sandwiching rollers by use of the following approximation formula (Formula i), so that an average elongation strain rate ε(R, L, V) in a sheet thickness direction is not less than a critical elongation strain rate ε*(R, L, V), where R is the radius of the sandwiching rollers, L is the average thickness of the polymer sheet which has been subjected to the elongation by rolling, V is the sheet take-off speed at the sandwiching rollers, and ε(R, L, V) is the average elongation strain rate in the sheet thickness direction.