Patent ID: 6200706
Filing Date: 2001-03-13
Classification: D04H,D21H,H01M

Abstract:
A nonwoven fabric for separators of non-aqueous electrolyte batteries which is produced by a wet paper making process, comprising:a nonwoven fabric constituted of organic fibers wherein the length of the fibers is 1-30 mm, the nonwoven fabric has a thickness of 10-100 .mu.m and the nonwoven fabric has a thickness non-uniformity index (Rpy) in machine direction of 1000 mV or less as determined below:thickness non-uniformity index (Rpy): a sample is allowed to run between two spherical tracers; variation of thickness of the sample in machine direction is measured using a film thickness measuring equipment which measures the variation of sample thickness as an electric signal through an electric micrometer by scanning the sample at a constant rate of 1.5 m/min in machine direction after zero point adjustment under the condition of .+-.15 .mu.m/.+-.3 V in sensitivity range of the electric micrometer; the resulting signal value is subjected to fast Fourier transform by a FFT analyzer using hanning window as a time window; a power spectrum (unit: mV.sup.2) is obtained by addition averaging of addition of 128 times; the power values in the frequency band of 2-25 Hz are totaled; the total is multiplied by 2/3; and the resulting value is raised to one-second power to obtain the thickness non-uniformity index (Rpy) (unit: mV).