Dry fibrous material for subsequent resin infusion

A method of making a slit tape or tow suitable for Automated Tape Laying (ATL) or Automated Fiber Placement (AFP), the method comprising:

• laminating a ply of structural fibers to a nonwoven veil of randomly arranged fibers to form a laminated structure;
• coating the laminated structure with a water-borne binder composition comprising one or more polymers selected from polyhydroxyethers, polyurethanes, a mixture thereof, a copolymer thereof, or a reaction product thereof in combination with a crosslinker and optionally a catalyst;
• drying the coated, laminated structure;
• and
• slitting the coated structure into tapes or tows.

A binder composition for forming a self-supporting fibrous material that can be slit without substantial fraying, wherein the binder composition is an aqueous dispersion comprising:

• a. a polyhydroxyether-polyurethane copolymer, wherein
• the polyhydroxyether portion of the copolymer contains a Bisphenol-A, and
• the polyurethane portion of the copolymer is based on a polyisocyanate and a polyol selected from a group consisting of aliphatic and aromatic polyether polyols, and polyester polyols;
• b. a methoxyalkyl melamine cross-linker;
• and
• c. a blocked sulfonic acid catalyst.