Epoxy resin impregnated yarn and the use thereof for producing a preform

Yarn comprised of reinforcing fiber filaments and a resin, infiltrated into the yarn, that can be repeatedly melted and solidified by cooling to room temperature,

• wherein the reinforing fiber filaments of the yarn are at least partially bound to one another by the infiltrating resin,
• wherein the yarn contains 2.5 to 2.5 wt.% of the infiltrating resin relative to its total weight,
• wherein the reinforcing fiber filaments are electrochemically pretreated carbon fiber filaments,
• wherein the infiltrating resin contains at least two bisphenol A epichlorohydrin epoxy resins H1 and H2 in the weight ratio H1:H2 of 1.1 to 1.4, H1 having an epoxy value of 1,850 to 2,400 mmol/kg and a molecular weight of 800 to 1,000 g/mol and solid at room temperature, and H2 having an epoxy value of 5,000 to 5,600 mmol/kg and a molecular weight of <700 g/mol and liquid at room temperature,
• wherein the infiltrating resin contains an additional third resin H3, H3 being a bisphenol A epichlorohydrin epoxy resin with an epoxy value of 450 to 650 mmol/kg, and a melting range of 110 to 130° C., and
• wherein the yarn contains a total of 0.5 to 1.7 wt.% of H1 and H2, and 2.3 to 5.5 wt.% of H3, relative to its total weight, and
• wherein the yarn is capable of being wound on, and unwound from, a bobbin.