Unidirectional reinforcement, a method of producing a unidirectional reinforcement and the use thereof
A unidirectional reinforcement and a method of producing a unidirectional reinforcement for use in applications where high quality and strength is required. The unidirectional reinforcement includes transversely arranged thin discrete flow passage formed to ensure resin flow properties in a direction transverse to the direction of the unidirectional rovings. Thin discrete flow passage forming means are secured on the unidirectional rovings by means of additional yarns running on the thin discrete flow passage forming means and transverse thereto.
1. A unidirectional reinforcement for the manufacture of fiber reinforced composites by a Closed Mold Method, the unidirectional reinforcement comprising:
continuous unidirectional rovings arranged in a longitudinal direction of the reinforcement and bonded to each other by a thermoplastic and/or thermoset binder,
the reinforcement having two longitudinal edges, a top surface and a bottom surface and continuous members arranged on at least one of the top surface and the bottom surface of the reinforcement,
the continuous members running in a direction transverse to the direction of the unidirectional rovings, wherein the continuous members include thin discrete flow passage forming means, for forming flow passages for resin, arranged transverse to the unidirectional rovings on at least one of the top surface and the bottom surface of the reinforcement,
the thin discrete flow passage forming means forming to the sides thereof transverse flow passages extending from one longitudinal edge of the unidirectional reinforcement to the opposite longitudinal edge thereof, wherein the flow passages are configured to facilitate, when wetting-out a stack of reinforcements, impregnation of the reinforcement with resin, and
the thin discrete flow passage forming means are secured on the unidirectional rovings by additional yarns running on and transverse to the thin discrete flow passage forming means, each additional yarn remaining continuously on the surface of the reinforcement having the thin discrete flow passage forming means laid thereon, the additional yarns being adhesively bonded to at least the unidirectional rovings.
2. The unidirectional reinforcement as recited in claim 1 , wherein the additional yarns are bonded to the unidirectional rovings by means of the thermoplastic and/or the thermoset binder.
3. The unidirectional reinforcement as recited in claim 1 , wherein the thin discrete flow passage forming means are monofilaments.
4. The unidirectional reinforcement as recited in claim 1 , wherein the additional yarns are provided with an additional thermoplastic and/or thermoset binder for securing the yarns on the unidirectional rovings.
5. The unidirectional reinforcement as recited in claim 1 , wherein the thin discrete flow passage forming means are parallel on the one surface they are laid on and positioned at a spacing of 2-50 mm on the unidirectional reinforcement.
6. The unidirectional reinforcement as recited in claim 1 , further comprises a discrete Z-direction resin flow facilitating means for facilitating resin flow in a thickness direction, in the unidirectional reinforcement.
7. The unidirectional reinforcement as recited in claim 6 , wherein the discrete Z-direction resin flow facilitating means are arranged to run in transverse direction back and forth between the two longitudinal edges of the reinforcement and travel between the top and bottom surfaces of the unidirectional reinforcement in a direction transverse to the unidirectional rovings.
8. The unidirectional reinforcement as recited in claim 6 , wherein the discrete Z-direction resin flow facilitating means is a single filament or a bonded bundle of a few filaments.
9. The unidirectional reinforcement as recited in claim 6 , wherein the discrete Z-direction resin flow facilitating means has a diameter or thickness of 100 to 300 μm under vacuum infusion having a vacuum of 500 to 980 mbar or RTM compression having a pressure of 100-2000 mbar.
10. A spar cap for a wind turbine comprising the unidirectional reinforcement of claim 1 .
11. A monoaxial or multiaxial preform or reinforcement product comprising the unidirectional reinforcement of claim 1 .
12. The unidirectional reinforcement as recited in claim 1 , wherein the continuous unidirectional rovings are continuously arranged in the direction transverse to the direction of the unidirectional rovings.
13. A unidirectional reinforcement comprising:
continuous unidirectional rovings arranged in parallel along a longitudinal direction of the reinforcement and bonded to each other by a thermoplastic and/or thermoset binder, wherein the reinforcement includes longitudinal edges, a surface extending between the longitudinal edges, wherein the surface is a top or bottom surface of the reinforcement;
continuous monofilaments on the surface of the reinforcement and aligned transverse to the longitudinal direction;
resin flow passages adjacent the surface and aligned transverse to the longitudinal direction and each resin flow passage is open at the longitudinal edges of the reinforcement, wherein each of the resin flow passages has a side adjacent one of the continuous monofilaments; and
yarns securing the continuous monofilaments to the unidirectional rovings, wherein the yarns are transverse to the continuous monofilaments and each yarn is on the surface of the reinforcement having the continuous monofilaments.
14. The unidirectional reinforcement as recited in claim 13 , wherein the continuous unidirectional rovings are continuously arranged in the direction transverse to the direction of the unidirectional rovings.