METHOD FOR PRODUCING A COMPOSITE COMPONENT

Abstract

The invention relates to a process for the production of a composite component (33) which comprises a molding (1) made of a thermoplastic polymer foam and which comprises a functional layer (37) made of an unfoamed thermoplastic, comprising the following steps: (e) insertion of the molding (1) made of thermoplastic polymer foam into a mold (3), (f) application of a thermoplastic polymer by an injection process, where the pressure during the application of the thermoplastic polymer is smaller than 100 bar.

Claims

1.-13. (canceled)

14. A process for the production of a composite component which comprises a molding made of a thermoplastic polymer foam and which comprises a functional layer made of an unfoamed thermoplastic, the process comprising: (a) inserting the molding made of thermoplastic polymer foam into a mold, (b) applying a thermoplastic polymer by an injection process, where the pressure during the application of the thermoplastic polymer is less than 100 bar.

15. The process according to claim 14, wherein the injection process is an injection-molding process, a transfer-molding process, or an injection-compression-molding process.

16. The process according to claim 15, wherein the injection-molding process is carried out with a pressure of less than 100 bar, with a holding pressure of less than 50 bar, and with an injection speed of less than 100 mm/s.

17. The process according to claim 14, wherein the thermoplastic polymer foam is a molded foam.

18. The process according to claim 14, wherein the polymer foam comprises an expanded thermoplastic polyurethane (ETPU) or a biodegradable, aliphatic-aromatic copolyester.

19. The process according to claim 14 wherein the thermoplastic polymer applied in step (b) is selected from the group consisting of polyamide, thermoplastic polyurethane, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, acrylate-styrene-acrylonitrile, acrylate-styrene-acrylonitrile/polycarbonate blend, polycarbonate, acrylonitrile-butadiene-styrene/polycarbonate blend, acrylonitrile-butadiene-styrene/polyamide blend, styrene-butadiene copolymer, polymethyl methacrylate, and combinations thereof.

20. The process according to claim 14, wherein the surface of the molding made of polymer foam is pretreated.

21. The process according to claim 20, wherein the pretreatment of the surface of the molding made of polymer foam comprises a corona treatment or plasma treatment.

22. The process according to claim 14, wherein the molding made of polymer foam has been manufactured from a polymer foam with a proportion of interstices in the range from 10 to 50%.

23. The process according to claim 14, wherein the melt temperature of the thermoplastic polymer applied in step (b) is in the range from 180 to 260 C.

24. The process according to claim 14, wherein the temperature of the mold is controlled to a temperature in the range from 10 to 60 C.

25. The process according to claim 14, wherein the thickness of the functional layer is in the range from 0.2 to 10 mm.

26. The process according to claim 14, wherein functional elements have been molded onto the functional layer.

Description

[0027] Embodiments of the invention are depicted in the figures and are explained in more detail in the description below.

[0028] FIG. 1 shows an apparatus for carrying out the process of the invention,

[0029] FIG. 2 is a three-dimensional diagram of a mold for carrying out the process.

[0030] FIG. 3 is a view of a section through a composite component of the invention.

[0031] FIG. 1 shows an apparatus for carrying out the process of the invention.

[0032] In order to produce a composite component from molding 1 made of a polymer foam 1 with a functional layer made of a thermoplastic polymer, the molding 1 made of polymer foam is inserted into a mold 3 for an injection process.

[0033] The insertion of the molding 1 made of polymer foam can by way of example be realized in that the molding 1 is inserted into a first mold half 5 of the mold 3. A second mold half 7 is then used to seal the first mold half 5. The diagram here shows, for the sealing process, a clamping unit 9, which is used to displace the second mold half 7 in the direction of the first mold half 5 until the two mold halves 5, 7 have been closed. Another possibility, alongside the insertion of the molding 1 made of polymer foam into the first mold half 5, is of course insertion of the molding 1 made of polymer foam into the second mold half 7, and displacement of the second mold half 5 together with the molding 1 made of polymer foam in the direction of the first mold half 5, until the mold 3 has been closed.

[0034] Once the mold 3 has been sealed, with the molding 1 made of polymer foam positioned therein, a thermoplastic polymer is injected into the mold. In the embodiment depicted here, this is achieved via an injection-molding process. In an injection-molding process, pellets 11 made of a thermoplastic polymer are usually introduced by way of an input unit, for example a feed hopper 13, into a reciprocating-screw machine 15. In the reciprocating-screw machine 15, the pellets are transported via rotation of a screw 17 in the direction of a nozzle 19. The pellets in the reciprocating-screw machine 15 are first compacted and then melted. The melting is to some extent achieved by virtue of a temperature rise during the compaction process. In addition, the housing 21 of the reciprocating-screw machine 15 is usually heated by heating apparatuses, for example heating tapes 23, from the outside, in order to assist the melting of the pellets made of thermoplastic polymer. Prior to the nozzle 19 there is a melt reservoir 25 into which the melt is conveyed. As soon as the melt reservoir 25 has been filled and the mold 3 has been closed, the screw is moved axially in the direction of the nozzle 19 with the aid of an advancer unit 27. The melt is thus forced from the melt reservoir 25 through the nozzle 19 and a runner system 29 into the mold 3, where it flows into the regions not filled by the molding 1 made of polymer foam.

[0035] Once the melt has been forced into the mold, the screw 17 is moved back to the starting position, and fresh melt is transported into the melt reservoir 25. At the same time, the melt in the mold 3 cools and solidifies. As soon as the injected polymer has achieved sufficient strength, the mold 3 is opened and the resultant composite component is removed.

[0036] In the invention, the injection process is carried out with an injection pressure of at most 100 bar and with a holding pressure of at most 50 bar, in order to prevent damage to the molding 3 made of polymer foam, and to obtain the desired properties of the composite component with the core of the molding 1 made of polymer foam. The injection pressure and the holding pressure here are measured at the advancer unit for the screw. Another result of this is that the melt being discharged from the nozzle 19 into the runner system 29 has a lower pressure. However, the pressure maintained must be sufficiently high that the melt fills all of the cavities in the mold 3. The lower the viscosity of the melt here, the lower the pressure that can be selected.

[0037] FIG. 2 shows by way of example the insertion of the molding 1 made of polymer foam into the first mold half 5 of the mold 3. In the first mold half 5 here there is a cavity 31 which can receive the molding 1 made of polymer foam. If the intention is to inject material around all sides of the molding 1 made of polymer foam, it is necessary to provide holder systems which hold the molding 1 made of polymer foam in position. The design of the holder systems here can be the same as the usual design of those used for processes in which a thermoplastic polymer is injected around a solid core or into undercut regions of a solid core.

[0038] FIG. 3 shows a section through an example of a composite component of the type that can be produced by the process of the invention.

[0039] The composite component 33 comprises a core 35, formed from the molding 1 made of polymer foam. A functional layer 37 has been formed around said core 35. The functional layer 37 here can completely enclose the core 35 or can have been applied only in certain regions on the core 35. This is advisable in particular when coating of the core 35 on only one side is desirable in order by way of example to obtain a prescribed surface structure, for example a decorative structure, or a smooth surface. It is also possible by this method to provide only the visible regions of the composite component 33 with a functional layer 37, which then by way of example can also be covered with a coating material.

[0040] The process of the invention can also provide a functional layer to a molding 1 made of polymer foam which has undercuts 39. The undercuts 39 have the further advantage of better retention of the functional layer 37 on the molding 1 made of polymer foam, since the undercuts 39 and the thermoplastic polymer that has flowed into the undercuts 39 and that constitutes the functional layer 37 additionally provide a mechanical connection.

[0041] Another possibility, alongside coating of the molding 1 made of polymer foam with a functional layer 37 for decorative purposes, is to establish technical properties via the functional layer 37; by way of example, the functional layer 37 can improve the mechanical stability of the composite component 33. It is additionally possible to provide functional elements 41 to the functional layer 37. By way of example, the functional elements 41 can be molded onto the functional layer 37 in a subsequent injection process. It is also alternatively possible that the functional elements 41 are molded simultaneously with the functional layer 37 in the injection process in step (b). Another possibility is moreover that the functional elements 41 are welded onto the functional layer in a subsequent step. Examples of functional elements 41 are ribs for the reinforcement of the composite component 33, elevations into which screw threads can be introduced, or external screw threads attached on the functional layer in order to permit releasable mechanical connection to another component. The functional elements can moreover also be clips, spacers, sealing elements, or any desired other elements for the fulfillment of particular functions.

[0042] The nature of the production process for the functional elements 41 determines whether these can have been manufactured from the thermoplastic polymer used for the functional layer 37 or from another polymer which can be bonded to the thermoplastic polymer of the functional layer 37.

KEY

[0043] 1 Molding [0044] 3 Mold [0045] 5 First mold half [0046] 7 Second mold half [0047] 9 Clamping unit [0048] 11 Pellets [0049] 13 Feed hopper [0050] 15 Reciprocating-screw machine [0051] 17 Screw [0052] 19 Nozzle [0053] 21 Housing [0054] 23 Heating tape [0055] 25 Melt reservoir [0056] 27 Advancer unit [0057] 29 Runner system [0058] 31 Cavity [0059] 33 Composite component [0060] 35 Core [0061] 37 Functional layer [0062] 39 Undercut [0063] 41 Functional element