Multidirectional filament reinforced tape and method of manufacture
The apparatus is a laminar shear resistant pre-impregnated resin tape for use in die forming pultrusion processes, with the tape formed by integrating three distinguishable layers, each with integrated parallel reinforcing filaments. The layers are arranged within the tape so that the filaments of adjacent layers are oriented at angles to each other. The tape of the preferred embodiment of the invention is constructed with the filaments of the center layer at 90 degrees to the length of the tape and the filaments of the two outer layers aligned with the length of the tape. The center layer can be more heavily loaded with filaments than conventional tapes, and the outer two layers have less than the amount of filament load of the center layer.
1. A method of making three layer multidirectional filament reinforced prepreg tape for use in a multilayer article constructed of layers of said tape laminated together comprising:
manufacturing unidirectional filament reinforced material for a center layer of the tape by a pultrusion process;
cutting the filament reinforced material for the center layer into pieces with lengths equal to the intended width of the final three layer tape;
stacking the cut pieces into a sheet feeder for feeding into a subsequent step of the process with the filament reinforcing of the cut pieces aligned in a selected direction;
feeding the stacked cut pieces into a separation space between two previously manufactured moving wet webs of prepreg which have reinforcing filaments running in the direction of the length of the moving wet webs, with the stacked pieces moving into the separation space and being sandwiched between the wet webs as the wet webs are converging at the entrance of a drying oven, and with the stacked pieces oriented so that the reinforcing filaments of the sandwiched pieces run transverse to the reinforcing filaments of the moving wet webs;
passing the assembly of the wet webs and the sandwiched pieces through the drying oven and drying the wet webs;
passing the assembly of the webs and the sandwiched pieces through a fusing oven in which the webs and sandwiched pieces are heated so the resins in the webs and the sandwiched pieces become molten; and
passing the assembly of the webs and the sandwiched pieces through a consolidator to press the assembly into a single prepreg tape that has filaments oriented in two directions.