Dry fibrous material for subsequent resin infusion
Disclosed herein is a dry, self-supporting fibrous material, the fibers of which have been treated with a binder composition. The fibrous material can be slit into tapes or tows that are suitable for use in an Automated Tape Laying (ATL) or Automated Fiber Placement (AFP) process. This fibrous material is suitable for forming preforms which are configured to receive a matrix resin by resin infusion in the manufacturing of structural composite parts.
1. A slit tape formed from slitting a dry, self-supporting fibrous material, the fibrous material comprising:
a ply of dry structural fibers laminated to a nonwoven veil of randomly-arranged fibers; and
a binder composition distributed to the structural fibers and the nonwoven veil, said binder composition comprising (i) a copolymer or a reaction product of polyhydroxyether and polyurethane and (ii) an aminoplast cross-linker,
wherein
the ply of structural fibers is in the form of unidirectional fibers or a woven fabric,
the binder composition is present in an amount of 15% or less by weight based on the total weight of the fibrous material and does not form a continuous film at the surface of the fibrous material, and
the fibrous material is permeable to liquid resin.
2. The slit tape of claim 1 ,
wherein the ply of structural fibers is not bonded to another layer other than the nonwoven veil.
3. The slit tape of claim 1 , wherein the binder composition further comprises a catalyst of sufficient acid strength to catalyze the crosslinking reaction.
4. The slit tape of claim 1 , wherein the fibrous material further comprises particles of an epoxy-based binder.
5. The slit tape of claim 1 , wherein the nonwoven veil has an areal weight of about 1 to 8 grams per square meter of the dry self-supporting fibrous material.
6. The slit tape of claim 1 , wherein the nonwoven veil comprises thermoplastic fibers that are soluble in epoxy resins.
7. The slit tape of claim 1 , wherein the veil comprises fibers made of carbon or polymeric material.
8. The slit tape of claim 1 , wherein the veil comprises glass or aramid fibers.
9. The slit tape of claim 4 , wherein the ply of structural fibers are in the form of unidirectional fibers and the nonwoven veil is comprised of carbon fibers.
10. The slit tape of claim 1 , wherein the nonwoven veil comprises carbon fibers.
11. The slit tape of claim 1 , wherein the slit tape has a width of 24 inches or less.
12. The slit tape of claim 1 , wherein the slit tape has a width of 1.5 inches or less.
13. A method of making the slit tape of claim 1 , comprising:
laminating the ply of structural fibers to the nonwoven veil of randomly arranged fibers to form a laminated structure;
coating the laminated structure with a water-borne binder composition comprising the copolymer or reaction product of polyhydroxyether and polyurethane, the aminoplast cross-linker, and optionally a catalyst;
drying the coated, laminated structure; and
slitting the coated structure into tapes.
14. The method of claim 13 , further comprising depositing particles of an epoxy-based binder onto the ply of structural fibers or to the veil prior to laminating.
15. A method comprising laying up a plurality of the slit tapes of claim 1 in an automated process to form a preform that can be infused with a liquid matrix resin.