Epoxy core with expandable microspheres
View Patent ↗A method of fabricating a formed structure with expandable polymeric shell microspheres. A first plurality of polymeric shell microspheres are heated from an unexpanded state to an expanded state to form a plurality of expanded microspheres. The plurality of expanded microspheres are mixed with an epoxy resin and a second plurality of unexpanded polymeric shell microspheres. The mixture is formed in a shape to create a preform. The preform is wrapped with fiber tape to create a wrapped preform. The wrapped preform is placed in a mold. The mold is heated and the second plurality of unexpanded microspheres expand from an unexpanded state to an expanded state. The mold is cooled and the formed structure is removed from the mold.
1. A composite article comprising a foam core wrapped with a tape for use as a hockey blade of a hockey stick, the article fabricated by the following steps:
heating a first plurality of unexpanded thermoplastic microspheres from an unexpanded state to a partially expanded state to create a plurality of partially expanded microspheres;
mixing the plurality of partially expanded microspheres with an epoxy resin, aramid pulp, and a second plurality of unexpanded thermoplastic microspheres to create an epoxy mixture;
forming the mixture to create a bottom and heel section of the hockey blade and placing a foam having a lower density than the mixture along a top or a toe to form the top or toe sections of the hockey blade thereby creating a preform for the hockey blade;
wrapping the preform with fiber tape to create a wrapped preform;
placing the wrapped preform in a mold;
wherein the plurality of partially expanded microspheres and the second plurality of unexpanded microspheres are configured to be expanded during a heating process to compress the fiber tape, and to bond to the epoxy resin and the foam; and
wherein the epoxy mixture is a viscous material such that it provides enough pressure to compress and consolidate the fiber tape.
2. The article according to claim 1 wherein the mixture further comprises fiber tape preimpregnated with resin.
3. The article according to claim 2 wherein the preform comprises a first face surface, a second face surface, a first edge surface and a second edge surface, the tape extending continuously around the first face surface, the first edge surface, the second face surface and the second edge surface.
4. The article according to claim 3 wherein the mixture further comprises chopped fiber and a curing agent.
5. The article according to claim 1 wherein the epoxy mixture further comprises 2 parts/weight of pre-expanded microspheres and 2.5 parts/weight of unexpanded microspheres.
6. The composite article according to claim 1 , wherein the epoxy mixture has the consistency of modeling clay.
7. The composite article of claim 1 wherein the polymeric shell microspheres are expanded to about 3 to 5 times their original size.
8. The composite article of claim 1 wherein the polymeric shell microspheres are expanded by heating to a diameter of about 40-50 microns.