Process for manufacturing composite materials

摘要

A process for the manufacture of a prepreg comprising feeding a layer of unidirectional conductive fibers having a defined width, bringing into contact with a first face of the fibers a first layer of resin comprising thermosetting resin, and compressing the resin and fibers together by passing over one or more impregnation rollers, wherein the pressure exerted onto the conductive fibers and resin does not exceed 40 kg per centimeter of the width of the conductive fibers, and the resin being in sufficient amount for the resin to enter the interstices of the fibers and leave a first outer layer of resin essentially free of unidirectional conductive fibers.

主权项

1. A process for the manufacture of a prepreg comprising the steps of:
providing a fibre web comprising a plurality of tows, said tows each comprising a plurality of unidirectional carbon filaments, said fibre web having first and second faces, spaces located between said tows and interstices located within said tows between said unidirectional carbon filaments and a width; contacting said first face of the fibre web with a first layer of resin at a pinch point to form a resin coated fibre web in which said first layer of resin does not impregnate the spaces located between said tows or said interstices, said first layer of resin comprising a first thermosetting resin; passing said resin coated fibre web through a first S-wrap stage comprising a single pair of S-wrap rollers wherein the viscosity of said first thermosetting resin and the pressure exerted on said first layer of resin by said single pair of S-wrap rollers is sufficient to farm a partially impregnated fibre web in which said first thermosetting resin is not present in said interstices; heating said partially impregnated fibre web a sufficient amount to reduce the viscosity of said first thermosetting resin in said partially impregnated fibre web to form a heated partially impregnated fibre web comprising a first thermosetting resin with reduced viscosity and having a temperature of between 100° C. and 130° C.; and passing said heated partially impregnated fibre web through a second S-wrap stage comprising three pairs of S-wrap rollers, said S-wrap rollers being at a temperature that is higher than the temperature of said heated partially impregnated fibre web wherein the viscosity of said first thermosetting resin with a reduced viscosity and the pressure exerted on said first thermosetting resin with reduced viscosity by said three pairs of S-wrap rollers is sufficient to form a fully impregnated fibre web in which said first thermosetting resin with reduced viscosity is present in said interstices.