Patent ID: 8791195

Claim:
A toughened film forming agent for use in a fiber sizing or a finish fiber coating, the toughened film forming agent consisting essentially of: a combination of a film forming polymer, and a toughening agent, where the combination is dispersed in water with a surfactant, wherein the toughening agent is selected from the group consisting of core shell polymers, rubber materials, thermoplastic materials, and combinations thereof, and the thermoplastic material is selected from the group consisting of methyl methacrylate and styrene-butadiene-methacrylate block copolymers, styrene-butadiene block copolymers, polysulfone, polyethersulfone, poly(butylene terephthalate) and combinations thereof, and wherein the film forming polymer is selected from the group consisting of epoxy resins, epoxy-polyurethane resins, epoxy-polyester resins, and combinations thereof, wherein, if present, the core shell polymers comprises from about 2 wt % to about 70 wt % based upon the weight of the toughened film forming agent; wherein, if present, the rubber material comprises from about 2 wt % to about 60 wt %, based upon the weight of the toughened film forming agent; and wherein, if present, the thermoplastic material comprises from about 1 wt % to about 50 wt %, based upon the weight of the toughened film forming agent.