| 摘要 |
<p>In the disclosed method of making a microporous sheet material a heat-formed (extruded, calendered, or pressed) film comprising (1) a polyurethane (preferably combined with an epoxidized soybean oil processing aid-a water insoluble plasticizer can also be included) capable of forming a nonporous film having a storage shear modulus (G') of about 0.4 to 5x108 dynes/cm.2 and a loss tangent at 0.2 cycle/sec. less than 0.5, both measured at 23 DEG C., and (2) distributed throughout the film, a plurality of <30 micron salt (e.g. NaCl) particles, is annealed prior to leaching of the salt from the film with an aqueous medium. The resulting microporous film is useful in making leatherlike sheet materials. Preferably, the film is embossed prior to leaching but after annealing.</p> |
