Microlayer structures and methods

Abstract

Improved microlayer structures and methods typically employing at least 4 stacked layers of polymers (e.g., including alternating layers of components A and B), such as that obtained by coextrusion. The layers each have a thickness of less than about 50 microns. One optional approach involves forming an intermediate form that includes at least one elongated member made from the plurality of layers, from which a shaped composite article may be made.

1 . An elongated member, comprising: at least 9 stacked and coextruded layers that each are continuous in profile and include at least 5 component A microlayers, and a component B microlayer interposed between each pair of adjacent component A microlayers, the component A microlayers and the component B microlayers have peak melting temperatures that differ by at least 5° C., wherein the component A microlayers include a first polymeric material selected from a polyolefin, a polyamide, a polyester, a (meth)acrylate, a polycarbonate, a polyvinylchloride, a (meth)acrylonitrile, a polyurethane, a polysulfone or any combination thereof; the component B microlayers each include a second polymeric material selected from a polyolefin, a polyamide, a polyester, a (meth)acrylate, a polycarbonate, a polyvinylchloride, a (meth)acrylonitrile, a polyurethane, a polysulfone or any combination thereof; wherein adjoining component A and compoundent B microlayers differs in molecular orientation, the elongated member is a fiber, a rod, a cord, a yarn, a tape, a filament, a strap, a film, a geophysical textile, a raffia, a woven fabric, an artificial grass, or a carpet, and
 the elongated member is prepared by drawing at a temperature above the melting point of one of components A and B and below the melting point of the other component. 
 
     
     
         2 - 61 . (canceled) 
     
     
         62 . The elongated member of  claim 1 , wherein the elongated member is an oriented film. 
     
     
         63 . The elongated member of  claim 62 , wherein the oriented film is a biaxially oriented film. 
     
     
         64 . The elongated member of  claim 62 , wherein the oriented film has a draw ratio of at least about 10, wherein the draw ratio is the ratio of the initial to final film thickness. 
     
     
         65 . The elongated member of  claim 62 , wherein the oriented film has a draw ratio of at least about 16, wherein the draw ratio is the ratio of the initial to final film thickness. 
     
     
         66 . The elongated member of  claim 63 , wherein the oriented film has a draw ratio of at least about 16, wherein the draw ratio is the ratio of the initial to final film thickness. 
     
     
         67 . The elongated member of  claim 66 , wherein the microlayers each have a thickness less than about 50 microns. 
     
     
         68 . The elongated member of  claim 67 , wherein the first polymeric material and the second polymeric materials include polyolefins. 
     
     
         69 . The elongated member of  claim 1 , wherein the polymer of at least one of the layers has a melting point below 125° C., and an adjoining layer has a peak melting point above 160° C. 
     
     
         70 . The elongated member of  claim 62 , wherein the polymer of at least one of the layers has a melting point below 125° C., and an adjoining layer has a peak melting point above 160° C. 
     
     
         71 . The elongated member of  claim 70 , wherein the polymers of at least two adjoining layers include propylene. 
     
     
         72 . The elongated member of  claim 71 , wherein the A component includes a propylene-ethylene copolymer that exhibits a melt flow rate at 230° C. per ASTM D1238 of 0.3 to 50 g/10 min; a density per ASTM D792 of 0.858 to 0.888 g/cc; an ethylene content of 5 to 25 wt %; a Melting Range from 50 to 135° C.; a Shore A Hardness from about 40 to about 90; and a flexural modulus per ISO 178 of 10 to 280 MPa and the B component includes a polypropylene homopolymer that exhibits a melt flow rate at 230° C. per ASTM D1238 of less than 7 g/10 min; a 1% secant flexural modulus of greater than 2000 MPa; a crystallinity of at least 70%; an isotactic pentad/triad ratio of greater than 85%; and a peak melting temperature of greater than 160° C. 
     
     
         73 . The elongated member of  claim 62 , further comprising a non-migratory processing or surface modification agent selected from silicones, a halogenated polymer, or a combination disposed on an exposed surface of at least one of the layers. 
     
     
         74 . The elongated member of  claim 1 , wherein the microlayers each have a thickness less than 50 microns, and the elongated member further comprises a layer that is not a microlayer. 
     
     
         75 . The elongated member of  claim 62 , wherein the oriented film is a stretch cling film. 
     
     
         76 . The elongated member of  claim 62 , wherein the oriented film is a blown film or a cast film. 
     
     
         77 . A method of making the elongated member of  claim 1 , comprising: coextruding a lamellar polymeric body including the component A layers and the component B layers, and drawing the lamellar polymeric body, wherein the step of drawing includes at least one stretch performed above the melting point of one layer, but below the melting point of another layer at a drawing temperature above the melting point of one of components A and B and below the melting point of the other component so that the component A and component B layers have a thickness less than about 50 microns and adjoining component A and component B microlayers differ in molecular orientation. 
     
     
         78 . The method of  claim 78 , wherein the step of drawing results in a draw ratio of greater than about 5; the first polymeric material includes a polyolefin; the second polymeric material includes a polyolefin; the method includes coextruding a film using a microlayer melt splitter or a hemispherical microlayer coextrusion feedblock; wherein the step of drawing includes biaxially drawing the lamellar polymeric body. 
     
     
         79 . A method for making a shaped composite article, comprising the steps of: a) providing at least one elongated member according to  claim 1 , wherein each of the microlayers has a thickness of less than about 50 microns; and
 b) processing the elongated member into an intermediate form that includes a plurality of repeating structural units that are generally free to move relative to each other, wherein the form is capable of being processed to form a shaped composite article; and c) at least partially consolidating the intermediate form.   
     
     
         80 . An article including a portion made according to the method of  claim 79 .