Patent ID: 6071450
Filing Date: 2000-06-06
Classification: B29C,B32B

Abstract:
Method for making a breathable, water degradable microlayer polymer film comprising the steps of:coextruding a non-water degradable, melt-extrudable polymer and a water degradable, melt-extrudable polymer to form a laminate comprising a non-degradable layer including the non-water degradable, melt-extrudable polymer and a degradable layer including a water degradable, melt-extrudable polymer;separating the laminate while the laminate is in a melt extrudable state to form a pair of laminate halves each including a portion of the non-degradable layer and a portion of the degradable layer;thinning and widening the laminate halves;stacking the laminate halves on top of one another to reform the laminate so that the laminate comprises a plurality of repeating laminate units in parallel stacking arrangement, each laminate unit comprising at least one non-degradable microlayer including the non-water degradable, melt-extrudable polymer and at least one degradable microlayer including the water degradable, melt-extrudable polymer; andrepeating the separating, thinning and widening, and stacking steps to form the laminate into the microlayer polymer film such that the microlayer polymer film comprises a plurality of degradable microlayers and a plurality of non-degradable microlayers, the microlayer polymer film has a water vapor transmission rate of at least about 3002/m.sup.2 /24 hr./mil, and the microlayer polymer film is water degradable.