Patent ID: 6099906
Filing Date: 2000-08-08
Classification: B29B

Abstract:
A process for impregnating a composite structural part in which a dry fiber preform made up of a plurality of plies of fabric is impregnated with a low viscosity resin, wherein the resin contains a heat-activated catalyst to control start of cure and a thixotropic agent to control resin flow characteristics and coating thickness, the process consisting essentially of the steps of:confining the dry fiber preform comprised of fabric within an impregnation vessel;evacuating gases from the interior of the impregnation vessel by vacuum pumping;conveying, while continuing the vacuum pumping, the resin from a resin storage vessel through fluid communication means into the impregnation vessel in an amount sufficient to completely immerse the fiber preform, wherein the impregnation vessel is held under vacuum until the fiber preform is completely immersed in the resin;holding the resin in the impregnation vessel for a sufficient amount of time to allow the resin to completely penetrate and saturate the fiber preform wherein the resin is uncured;withdrawing excess resin from the impregnation vessel back into the resin storage vessel;lifting the saturated fiber preform from the impregnation vessel into a hanging position such that any excess resin remaining on the saturated fiber preform drips off into resin collection means, the saturated fiber preform thereby containing the correct amount of resin after excess resin has dripped off due to the predetermined low viscosity and controlled thixotropic nature of the resin; andcuring the resin by conveying the saturated preform to a curing apparatus wherein the preform is heated to a temperature sufficient to activate the catalyst, thereby setting and curing the resin to form the composite structural part, and with the proviso that the process steps prior to the curing step are conducted at a temperature below that necessary to activate the catalyst.