Resin-soluble veils for composite article fabrication and methods of manufacturing the same

Abstract

Embodiments of the invention are directed to resin-soluble thermoplastic veils for use in liquid resin infusion processes, methods of manufacturing resin-soluble thermoplastic veils for use in liquid resin infusion processes, and methods of manufacturing composite articles using resin-soluble thermoplastic veils for use in liquid resin infusion applications. The resin-soluble thermoplastic veils according to embodiments of the invention and of which function as a toughening agent in composites having the veil incorporated therein have improved characteristics including, but not limited to, increased uniformity and decreased thickness relative to prior art veils. These characteristics translate into improvements in the processing of a composite article including, but not limited to, a substantial or complete elimination in premature dissolution of the veil during cure. The resultant composite article also realizes improvements including, but not limited to, distribution evenness of the toughening agent throughout the composite.

1 . A non-woven engineered veil comprised of a plurality of fibers having a mean diameter of between 10 microns and 16 microns wherein less than 20% of the fibers have a diameter of less than 8 microns, the textile having a fabric areal weight variation of less than 10% across the width of the textile, the textile having a thickness achieved by a calendaring process. 
     
     
         2 . The non-woven engineered veil of  claim 1  wherein the textile has a fabric areal weight of between 5 grams per square meter and 80 grams per square meter and a thickness of between 20 μm and 90 μm. 
     
     
         3 . The non-woven engineered veil of  claim 1  wherein a material comprising the plurality of fibers is a polymer having a native solid phase and adapted to undergo at least partial phase transition to a fluid phase on contact with a component of a curable composition in which the polymer is soluble at a temperature which is less than the temperature for substantial onset of curing of the curable composition and which temperature is less than the inherent melting temperature of the non-woven engineered veil. 
     
     
         4 . The non-woven engineered veil of  claim 3  wherein the polymer has a melt flow index of between 18 and 38. 
     
     
         5 . The non-woven engineered textile of  claim 1  wherein said plurality of fibers are made of thermoplastic polymer. 
     
     
         6 . The non-woven engineered veil of  claim 1 , further comprising, a plurality of perforations throughout the textile. 
     
     
         7 . The non-woven engineered veil of  claim 1  wherein the textile is manufactured by a melt-extnision process selected from melt blown or spunbond. 
     
     
         8 . The non-woven engineered veil of  claim 7  wherein the process is a melt-blown process, at least one processing parameter of the process is set to be within a predetermined range, above a predetermined threshold or below a predetermined threshold, the at least one processing parameter comprising one of melt pump speed, collector rate speed, airflow rate, and airflow temperature. 
     
     
         9 . A method of manufacturing a non-woven engineered veil using a melt-blown process, comprising:
 increasing a melt pump speed while simultaneously decreasing an airflow rate;   loading a material into an extruder wherein the material is a polymer having a native solid phase and adapted to undergo at least partial phase transition to a fluid phase on contact with a component of a curable composition in which the polymer is soluble at a temperature which is less than the temperature for substantial onset of curing of the curable composition and which temperature is less than the inherent melting temperature of a resultant non-woven engineered veil; and   causing the polymer to be extruded from a die head in the form of fibers and onto a moving collector, the fibers forming a non-woven engineered veil wherein increasing the melt pump speed while decreasing the airflow rate provides fibers having a mean diameter of between 10 microns and 16 microns wherein less than 20% of the fibers have a diameter of less than 8 microns, the veil having a fabric areal weight variation of less than 10% across the width of the textile.   
     
     
         10 . The method of manufacturing non-woven engineered veil of  claim 9 , further comprising, subjecting the non-woven engineered veil to a calendering process. 
     
     
         11 . The method of manufacturing non-woven engineered veil of  claim 9  wherein the veil has a fabric areal weight of between 5 grams per square meter and 80 grams per square meter and a thickness of between 20 μm and 90 μm. 
     
     
         12 . The method of manufacturing non-woven engineered veil of  claim 9  wherein a material comprising the plurality of fibers is a polymer having a native solid phase and adapted to undergo at least partial phase transition to a fluid phase on contact with a component of a curable composition in which the polymer is soluble at a temperature which is less than the temperature for substantial onset of curing of the curable composition and which temperature is less than the inherent melting temperature of the non-woven engineered veil. 
     
     
         13 . The method of manufacturing non-woven engineered veil of  claim 9  wherein the polymer has a melt flow index of between 18 and 38. 
     
     
         14 . The method of manufacturing non-woven engineered veil of  claim 9 , further comprising, subjecting the textile to an off-line perforation process, the off-line perforation process effectuated by one of a needle or a laser. 
     
     
         15 . The method of manufacturing non-woven engineered veil of  claim 9  wherein at least one processing parameter of the melt-blown process is set to be within a predetermined range, above a predetermined threshold or below a predetermined threshold, the at least one processing parameter comprising one of a melt pump speed, collector rate speed, airflow rate, and an airflow temperature. 
     
     
         16 . A preform for composite article manufacturing, comprising:
 at least one structural component comprising reinforcement fibers; and   at least one, non-woven engineered veil contacting the structural component, the veil comprised of a plurality of fibers having a mean diameter of between 10 microns and 16 microns wherein less than 20% of the fibers have a diameter of less than 8 microns, the textile having a fabric areal weight variation of less than 10% across the width of the veil, the plurality of fibers comprised of polymer having a native solid phase and adapted to undergo at least partial phase transition to a fluid phase on contact with a component of a curable composition in which the polymer is soluble at a temperature which is less than the temperature for substantial onset of curing of the curable composition and which temperature is less than the inherent melting temperature of the non-woven engineered veil.   
     
     
         17 . The preform for composite article manufacturing of  claim 16  wherein the structural component is in the form of a plurality of adjacent reinforcement fiber layers and the non-woven engineered veil is interposed between pairs of adjacent reinforcement fiber layers, and wherein said plurality of fibers in the non-woven engineered veils are made of thermoplastic polymer. 
     
     
         18 . The preform for composite article manufacturing of  claim 16  wherein the veil has a fabric areal weight of between 5 grams per square meter and 80 grams per square meter and a thickness of between 20 μm and 90 μm as a result of a calendering process, and wherein the polymer has a melt flow index of between 18 and 38. 
     
     
         19 . The preform for composite article manufacturing of  claim 16 , further comprising, a plurality of perforations throughout the veil. 
     
     
         20 . A method of manufacturing a composite article using a liquid resin infusion process, comprising:
 arranging a plurality of structural components comprising reinforcement fibers within a mold:   interleafing a plurality of non-woven engineered veils with the plurality of structural components, the plurality of veils comprised of a plurality of fibers having a mean diameter of between 10 microns and 16 microns wherein less than 20% of the fibers have a diameter of less than 8 microns, and a fabric areal weight variation of less than 10% across the width of each veil, the interleafed arrangement forming a preform:   contacting the preform with a resin wherein the resin is at an initial temperature of less than 75° C.:   heating the preform to a predetermined temperature threshold wherein a majority of the fibers are dissolved before the predetermined temperature threshold is reached: and allowing the preform to cure while the preform is held at the predetermined temperature threshold for a predetermined time period.   
     
     
         21 . The method of manufacturing a composite article using the liquid resin infusion process of  claim 20  wherein the predetermined temperature threshold is 180° C., and the polymer has a melt flow index of between 18 and 38. 
     
     
         22 . The method of manufacturing a composite article using the liquid resin infusion process of  claim 20  wherein the plurality of fibers comprise a polymer having a native solid phase and adapted to undergo at least partial phase transition to a fluid phase on contact with a component of a curable composition in which the polymer is soluble at a temperature which is less than the temperature for substantial onset of curing of the curable composition and which temperature is less than the inherent melting temperature of the non-woven engineered veil.