ASSEMBLING FIBER-REINFORCED FOAMS

Abstract

The present invention relates to a process for converting moldings. Here, a molding comprising a foam and at least one fiber (F), wherein the fiber (F) is with a fiber region (FB2) located inside the molding is at least partially divided at least once, wherein at least one fiber (F) is completely divided. The invention further relates to the thus obtainable converted molding and to a panel comprising the converted molding and at least one layer (S1). The present invention further relates to a process for producing the panel and to the use of the converted molding/the panel according to the invention as a rotor blade in wind turbines for example.

Claims

1.-16. (canceled)

17. A process for converting a molding comprising the following steps a) and b): a) providing a molding comprising a foam and at least one fiber (F), wherein the fiber (F) is with a fiber region (FB2) located inside the molding and surrounded by the foam, b) at least partially dividing the molding at least once, wherein at least one fiber (F) is completely divided to obtain a converted molding, wherein in step a) the molding is provided when at least one fiber (F) is partially introduced into the foam with the result that the fiber (F) is with the fiber region (FB2) located inside the molding and surrounded by the foam while a fiber region (FB 1) of the fiber (F) projects from a first side of the molding and a fiber region (FB3) of the fiber (F) projects from a second side of the molding and the fiber region (FB 1) and/or the fiber region (FB3) are then optionally removed, wherein partial introduction is optionally effected by steps al) to a6): a1) optionally applying at least one layer (S2) and optionally applying at least one carrier layer (TS) to at least one side of the foam, a2) producing one hole per fiber (F) in the foam and optionally in the layer (S2) and optionally in the carrier layer (TS), wherein the hole extends from a first side to a second side of the foam and optionally through the layer (S2) and optionally through the carrier layer (TS), a3) providing at least one fiber (F) on the second side of the foam, a4) passing a needle from the first side of the foam through the hole to the second side of the foam and optionally passing the needle through the layer (S2) and optionally passing the needle through the carrier layer (TS), a5) securing at least one fiber (F) to the needle on the second side of the foam and a6) returning the needle along with the fiber (F) through the hole, so that the fiber (F) is with the fiber region (FB2) located inside the molding and surrounded by the foam while the fiber region (FBI) of the fiber (F) projects from a first side of the molding or optionally from the layer (S2) or optionally from the carrier layer (TS) and the fiber region (FB3) of the fiber (F) projects from a second side of the molding, wherein the at least partial dividing of the molding in step b) is effected with a cutting tool.

18. The process according to claim 17, wherein i) the at least partial dividing of the molding in step b) is effected without material removal. ii) the at least partial dividing of the molding in step b) is effected with a knife.

19. The process according to claim 17, wherein step a) comprises providing a molding in which a fiber region (FB1) of the fiber (F) projects from a first side of the molding, a fiber region (FB1) of the fiber (F) projects from a first side of the molding and a fiber region (FB3) of the fiber (F) projects from a second side of the molding.

20. The process according to claim 17, wherein i) the at least partial dividing of the molding in step b) is effected at an angle in the range from 0 to 90 and/or in the range from 45 to 90 and/or in the range from 70 to 90, in each case relative to the thickness direction (d) of the molding, and/or ii) the at least partial dividing of the molding in step b) is effected parallel to the first side of the molding, the molding optionally being completely divided parallel to the first side of the molding in step b), and/or iii) the molding is partially divided in step b), the molding in step b) preferably being divided at an angle in the range from 0 to 45 relative to the thickness direction (d) of the molding, wherein 0.01 to 5 mm and/or 0.01% to 10%, of the total thickness of the molding remains undivided, and/or iv) the molding is partially divided in step b) so that the obtained converted molding comprises units, the units being rectangular and/or v) between step a) and step b) at least one carrier layer (TS) is applied to the molding, wherein optionally between step a) and step b) at least one carrier layer (TS) is applied to the molding and in step b) the molding is completely divided, wherein the carrier layer (TS) is not divided, the carrier layer (TS) optionally being open-pored.

21. The process according to claim 17, wherein the foam has been produced from a particle foam, an extruded foam, a reactive foam and/or a batch foam.

22. The process according to claim 17, wherein the foam is based on at least one polymer selected from the group consisting of polystyrene, polyester, polyphenylene oxide, a copolymer produced from phenylene oxide, a copolymer produced from styrene, polyaryl ether sulfone, polyphenylene sulfide, polyaryl ether ketone, polypropylene, polyethylene, polyamide, polyamide imide, polyether imide polycarbonate, polyacrylate, polylactic acid, polyvinyl chloride, polyurethane, and mixtures thereof.

23. The method according to claim 17, wherein i) the fiber (F) in step a) is a single fiber or a fiber bundle, and/or) ii) the fiber (F) in step a) is an organic, inorganic, metallic or ceramic fiber or a combination thereof, and/or iii) the fiber (F) in step a) is employed in the form of a fiber bundle having a number of individual fibers per bundle of at least 10 in the case of glass fibers and 1000 to 50000 in the case of carbon fibers, and/or iv) the fiber region (FB1) and the fiber region (FB3) each independently of one another account for 0.1% to 45% and the fiber region (FB2) accounts for 10% to 99.8% of the total length of a fiber (F) in step a), and/or v) the fiber (F) in step a) has been introduced into the foam at an angle of 0 to 60 or of 10 to 70, relative to the thickness direction (d) of the molding and/or vi) in the molding in step a) the first side of the molding from which the fiber region (FB 1) of the fiber (F) projects is opposite the second side of the molding from which the fiber region (FB3) of the fiber (F) projects and/or vii) the molding in step a) comprises a multiplicity of fibers (F) and/or comprises more than 10 fibers (F) or fiber bundles per m.sup.2.

24. The process according to claim 17, wherein the steps a2) and a4) are performed simultaneously.

25. A converted molding obtained by the process according to claim 17.

26. The converted molding according to claim 25 wherein the converted molding comprises a carrier layer (TS).

27. A panel comprising at least one converted molding according to claim 25 and at least one layer (S1).

28. The panel according to claim 27, wherein the layer (S1) comprises at least one resin.

29. The panel according to claim 27, wherein the layer (S1) additionally comprises at least one fibrous material, where) i) the fibrous material comprises fibers in the form of one or more plies of chopped fibers, nonwovens, non-crimp fabrics, knits and/or wovens, and/or ii) the fibrous material comprises organic, inorganic, metallic or ceramic fibers.

30. The panel according to claim 27, wherein) i) the fiber region (FB1) of the fiber (F) is in partial or complete, preferably complete, contact with the layer (S1), and/or ii) the panel comprises between at least one side of the converted molding and at least one layer (S1) at least one layer (S2), wherein the layer (S2) is composed of sheetlike fiber materials or polymeric films, and/or iii) the panel comprises two layers (S1) and the two layers (S1) are each attached at a side of the converted molding that is opposite the respective other side of the converted molding, and/or iv) the panel has an at least singly curved surface, and/or v) the thickness of the panel varies over the width and/or over the length of the panel by at least 0.5 mm/m.

31. A process for producing a panel according to claim 27, wherein the at least one layer (S1) is produced, applied and cured on a converted molding in the form of a reactive viscous resin, by liquid impregnation methods.

32. A rotor blade for a wind turbine comprising the converted molding according to claim 25.

33. The process according to claim 17, wherein the foam has been produced from an extruded foam produced in a process comprising the following steps: I) providing a polymer melt in an extruder, II) introducing at least one blowing agent into the polymer melt provided in step I) to obtain a foamable polymer melt, III) extruding the foamable polymer melt obtained in step II) from the extruder through at least one die aperture into an area at lower pressure, with expansion of the foamable polymer melt to obtain an expanded foam, IV) calibrating the expanded foam from step III) by conducting the expanded foam through a shaping tool to obtain the extruded foam. V) optional material-removing processing of the extruded foam obtained in step IV), wherein i) the polymer melt provided in step I) optionally comprises at least one additive, and/or ii) at least one additive is optionally added during step II) to the polymer melt and/or between step II) and step III) to the foamable polymer melt, and/or iii) at least one additive is optionally applied during step III) to the expanded foam and/or during step IV) to the expanded foam, and/or iv) at least one layer (S2) is optionally applied to the extruded foam during and/or directly after step IV), and/or at least one carrier layer (TS) is optionally applied to the extruded foam during and/or directly after step IV).

Description

EXAMPLES

[0217] Characterization

[0218] The properties of the foams, of the moldings, of the converted moldings and of the panels are determined as follows:

[0219] Smallest dimension of the cell (c-direction):

[0220] The smallest dimension of the cells is determined by statistical analysis of the micrographs analogously to anisotropy.

[0221] Density:

[0222] The density of the pure foams is determined according to ISO 845 (October 2009 version).

[0223] Resin absorption:

[0224] For resin absorption, foams are compared after material has been removed from the surface by planing. In addition to the employed resin systems, the foam slabs and glass non-crimp fabrics, the following auxiliary materials are used: nylon vacuum film, vacuum sealing tape, nylon flow aid, polyolefin separation film, polyester tearoff fabric and PTFE membrane film and polyester absorption fleece. Panels are produced from the moldings by applying fiber-reinforced outer plies by means of vacuum infusion. Applied to each of the top side and the bottom side of the foams are two plies of Quadrax glass non-crimp fabric (roving: E-Glass SE1500, OCV; textile: Saertex, isotropic laminate [0/45/9045] of 1200 g/m.sup.2 in each case). For the determination of the resin absorption a separation film is inserted between the foam and the glass non-crimp fabric, in contrast with the standard production of the panels. In this way, the resin absorption of the pure foam is determinable. The tearoff fabric and the flow aids are attached on either side of the glass non-crimp fabrics. The construction is subsequently equipped with gates for the resin system and gates for the evacuation. Finally, a vacuum film is applied over the entire construction and sealed with sealing tape, and the entire construction is evacuated. The construction is prepared on an electrically heatable table having a glass surface.

[0225] The resin system used is amine-curing epoxy (resin: BASF Baxxores 5400, curing agent: BASF Baxxodur 5440, mixing ratio and further processing as per data sheet). After the mixing of the two components the resin is evacuated at down to 20 mbar for 10 minutes. Infusion onto the pre-temperature-controlled construction is effected at a resin temperature of 23+/2 C. (table temperature: 35 C.). By means of a subsequent temperature ramp of 0.3 K/min from 35 C. to 75 C. and isothermal curing at 75 C. for 6 h, it is possible to produce panels consisting of the moldings and glass fiber-reinforced outer plies.

[0226] The foams are initially analyzed according to ISO 845 (October 2009 version) to obtain the apparent density of the foam. After the resin system has cured, the processed panels are trimmed in order to eliminate excess resin accumulations in the edge regions as a result of imperfectly fitting vacuum film.

[0227] The outer plies are then removed and the foams present are analyzed according to ISO 845. The difference in the densities gives the absolute resin absorption. Multiplication by the thickness of the foam then gives the corresponding resin absorption in kg/m.sup.2.

[0228] Production of the Foam and of the Molding

[0229] The film was produced as a sheet in a tandem extrusion plant. The melting extruder (ZSK 120) was supplied continuously with polyphenylene ether masterbatch (PPE/PS masterbatch, Noryl C6850, Sabic) and polystyrene (PS 148H, BASF), in order to produce an overall blend consisting of 25 parts PPE and 75 parts PS. In addition, additives such as talc (0.2 parts) were metered in via the intake as a PS masterbatch (PS 148H, BASF). Blowing agents (CO.sub.2, ethanol and i-butane) are injected into the injection port under pressure. The total throughput including the blowing agents and additives is 750 kg/h. The blowing agent-containing melt is cooled down in a downstream cooling extruder (ZE 400) and extruded through a slot die. The foaming melt is taken off by a heated calibrator, the surfaces of which have been coated with Teflon, via a conveyor belt and formed to slabs. Typical slab dimensions prior to mechanical processing are about width 800 mm (y direction) and thickness 60 mm (z direction). The sheets were then trimmed to 20 mm for the reinforcement. The properties of the thus obtained foam (BS1) are reported in table 1

TABLE-US-00001 TABLE 1 BS1 Production process () extrusion Polymer () PPE/PS c-direction (mm) 0.07 z direction (mm) 20 Resin absorption (kg/m.sup.2) 0.2 Density (kg/m.sup.3) 40

[0230] The thus obtained foam (BS1) is reinforced with glass fibers (rovings, E-Glas, 900 tex, 3B). The glass fibers are introduted in the form of rovings at an angle of 45 in four* different spatial directions at an angle 13 of 90 to one another. The glass fibers have been introduced in a regular rectangular pattern with equal distances a.sub.1=a.sub.2=16 mm. In addition, on both sides about 5.5 mm of the glass fibers are left to overhang at the outer ply to improve the bonding to the glass fiber mats introduced later as outer plies. The fibers/fiber rovings are introduced in an automated mariner by a combined sewing/crochet process. First of all, a hook needle (diameter of about 1.1 mm) is used to penetrate completely from the first side to the second side of the foam. On the second side a roving is hooked into the hook of the hook needle and then pulled from the second side through the hole and back to the first side of the foam. Finally, the roving is cut off on the second side and the roving loop formed is cut open at the needle. The hook needle is thus ready for the next operation.

[0231] Converting of the Foams

[0232] a) introduction of slots

[0233] Slots were introduced into the obtained fiber-reinforced foams (moldings) with a spacing of 25 mm50 mm and a slot depth of 16 mm. In the inventive example B1 a knife blade (geometry: width 0.5 mm, cutting angle 18, compressed to 26 for 0.1 to 0.2 mm at the cutting edges) was applied to a matrix and at an angle of 17 to 18 drawn through the molding at a rate of 30 m/min. In comparative example V2 the slots were introduced via a rotating saw blade (geometry: diameter 250 mm, thickness 0.8 mm, 28 teeth, from Miear, no. 45540) at a rotational speed of 4000 rpm and an advancing rate of 20 to 30 m/min.

[0234] The results may be found in table 2.

TABLE-US-00002 TABLE 2 B1 V2 Slot width 0.3 mm 1.1 mm Slot constant thickness, no damage to foam, rough surface, quality damage to foam, smooth uneven thickness, abraded cut edge material in slot Emission few, if any, particles, no chunks of the foam and of the chunks of the foam fibers, pulled-out fibers, temperature profile at the foam pulled-out no individual fibers and in some fibers cases fiber bundles partially or completely pulled out

[0235] b) scarfing of moldings

[0236] Scarfings were introduced into the fiber-reinforced foams (moldings) produced previously. Example B3 employed a splitting machine which divides the molding using a rotary knife belt (geometry: depth 80 mm, thickness 1 mm, length 8000 mm, phase 28). The knife is continually sharpened during operation. The molding is held on a vacuum table. The scarfing angle is 2

[0237] Comparative example V4 employed a horizontal wire cutting machine with a vacuum table. A wedge-shaped scarfing was cut out at an angle of 3 at a rotational speed of 61 m/s and an advancing rate of 0.25 m/min. The results are reported in table 3.

TABLE-US-00003 TABLE 3 B3 V4 Scarfing very good surface, cleanly damage to foam, fibers in wire quality divided fibers, no damage direction only deflected and not to foam, exact adherence to divided, burnt areas in foam, scarfing angle, surface large local deviations in scarfing partially closed again angle. Emission few, if any, particles, no chunks of the foam and of the chunks of the foam fibers, pulled-out fibers, temperature profile at the foam pulled-out no individual fibers and in some fibers cases fiber bundles partially or completely pulled out

[0238] c) smoothing/surficial removal of fibers in the moldings

[0239] The previously produced fiber-reinforced foams (moldings) were smoothed by surficial removal of the fibers.

[0240] Example B5 employed a splitting machine which divides the molding using a rotary knife belt (geometry: depth 80 mm, thickness 1 mm, length 8000 mm, phase 28). The knife was continually sharpened during operation. The moldings were held on a vacuum table and between 0.3 and 1.5 mm of foam were removed.

[0241] Comparative example V6 employed a horizontal wire cutting machine with a vacuum table. The rotational speed was 61 m/s at an advancing rate of 0.25 m/min.

[0242] The results can be seen in table 4.

TABLE-US-00004 TABLE 4 B5 V6 Cut very good surface, cleanly damage to foam, fibers in wire quality divided fibers, no damage direction only deflected and not to foam, surface partially divided, burnt areas in foam, closed again large local deviations in the cut. Emission few, if any, particles, no chunks of the foam and of the chunks of the foam fibers, pulled-out fibers, temperature profile at the foam pulled-out no individual fibers and in some fibers cases fiber bundles partially or completely pulled out