| 摘要 |
A method of consolidating thermoplastic fibrous layers. The method begins with providing a plurality of fibers, where the fibers have a core with an exterior surface portion comprising polypropylene and a first layer disposed on at least a portion of the core. The first layer contains a first polymer, where the first polymer contains at least 70% α-olefin units and is characterized by a melting temperature less than the melting temperature of the exterior surface of the core. These fibers are formed into a fibrous layer. Next, a second layer is applied to the fibrous layer such that the second layer covers at least a portion of the first layers of the fibers. The second layer contains a second polymer being a co-polymer having at least 50% α-olefin units which is characterized by a number-average molecular weight of about 7,000 g/mol to 50,000 g/mol, a viscosity of between about 2,500 and 150,000 cP measured at 170° C., and a melting temperature lower than the melting temperature of the exterior surface of the core. The viscosity of the second polymer is less than a tenth of the viscosity of the first polymer measured at 170° C. Next, heat and optionally pressure are applied to the fibrous layer causing at least a portion of the second layers of the fibers in each fibrous layer to fuse to other first or second layers of the fibers within the same fibrous layer, at least a portion of the second layers of the fibers of each fibrous layer fuse with at least a portion of the first or second layers of the fibers in an adjacent fibrous layer, and at least a portion of the interstices to be filled with a blend of the first and second polymers, where the blend filling the interstices comprises at least 80% wt the second polymer.
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