The manufacture method of battery separator and the battery separator

A kind of manufacture method of battery separator and the battery separator, the battery separator is the battery separator that the modified porous layer comprising fluororesin and inorganic particulate or cross-linked polymer particle is laminated with the one side for the polyolefin micro porous polyolefin membrane that thickness is less than 16 μm, (a) closing temperature of the polyolefin micro porous polyolefin membrane is less than 135 DEG C, and (b) impermeable manner rate of change is 1 × 10 4 More than sec/100cc/ DEG C, and the battery separator meets formula 1 and formula 2.0.01≤absT (1200)≤0.30 formula 1, absT (1200)：After modified porous layer is peeled off from polyolefin micro porous polyolefin membrane, the every 10 μ m thick polyolefin micro porous polyolefin membrane measured using infrared spectrum measurement (transmission beam method) is 1,200cm - 1 Nearby there is the absorbance of the absorption at peak；0.001≤absR (1200)≤0.030 formula 2, absR (1200)：The polyolefin micro porous polyolefin membrane measured using infrared spectrum measurement (bounce technique) with modified porous layer for opposite side face 1,200cm - 1 The absorbance at peak greatest around.The present invention, which is provided, to be had cementability to electrode and closes that performance, electrolytic solution permeability be excellent, manufacture method suitable for the battery separator of high-capacity battery and the battery separator.