Manufacturing methods for polyolefin microporous sheets, battery separators, filter materials, and polyolefin microporous extended films using polyolefin microporous sheets, battery separators, and filter materials.

Abstract

This invention provides a raw material for making polyolefin microporous extended films, which has excellent output characteristics when used as a battery separator, and can be used as a filter material with both foreign matter removal performance and high processing capacity, and can be used to obtain filter materials for liquids and gases. This invention relates to a polyolefin microporous sheet that satisfies any one of the following (i), (ii), and (iii): (i) a thickness of 30-500 μm, a bubble point pressure of 20-1000 kPa measured using Galwick, and a tensile strength of 0.5-10.0 MPa; or (ii) a thickness of 30-500 μm, a weight-average molecular weight of less than 1 million, a weight reduction rate of 0.2-10.0 wt% as shown in Formula 1, and air permeability; or (iii) a puncture strength equivalent to 20-150 mN for a thickness of 10 μm at 23°C, a puncture strength equivalent to 10-45 mN for a thickness of 10 μm at 125°C, and a bubble point pressure of 20-1000 kPa measured using Galwick. Formula 1: Weight reduction rate (wt%) = (weight before dichloromethane washing - weight after dichloromethane washing) / weight before dichloromethane washing × 100