SANDWICH PANEL FOR A CAR ABLE TO CARRY A LOAD

Abstract

Sandwich panel for use in a vehicle comprising at least a core layer and two fibrous layers in contact with and firmly connected to the core layer, both sides being impregnated with polyurethane whereby the polyurethane is embedding the fibers and binding to the board material, and whereby the sandwich panel further comprises at least a polyether polyurethane foam layer fully impregnated with polyurethane and in contact and firmly connected to the outer surface of at least one fibrous layer by the polyurethane, and a skin layer on the outer surface of the polyether polyurethane foam not in contact with the fibrous layer consisting of compressed polyurethane.

Claims

1. A sandwich panel for use in a vehicle comprising at least a core layer covered on both sides with a fibrous layer to form a sandwich, both sides being impregnated with polyurethane whereby the polyurethane is embedding the fibers and binding to the core material, characterized in that the sandwich panel further comprises: at least a resilient slab foam layer based on polyether polyurethane fully penetrated and engulfed with polyurethane and in contact and firmly connected to the outer surface of at least one fibrous layer by the polyurethane; a skin layer on the outer surface of the polyether polyurethane foam not in contact with the fibrous layer consisting of compressed polyurethane; and whereby the polyurethane bulge inside the core layer to bind the adjacent layer to the core layer without fully filling the core layer structure.

2. The sandwich panel according to claim 1 whereby the polyether polyurethane foam layer is having a surface weight of between 48 to 240 gsm or between 72 and 192 gsm.

3. The sandwich panel according to claim 1, whereby the polyurethane foam used for impregnation is based on polyester or polyether polyol.

4. The sandwich panel according to claim 1, whereby the polyurethane used for impregnation has an area weight of between 200 and 2000 gsm per surface impregnated.

5. The sandwich panel according to claim 1, whereby the first and second fibrous mat can be made up of the same or different fibers, fiber mixtures, or fibrous layers.

6. The sandwich panel according to claim 1, whereby the first and or second fibrous mat comprises at least one of inorganic fibers, synthetic fibers, polyolefin, organic regenerated fibers, natural fibers, animal fibers, and a mixture of one or more thereof.

7. The sandwich panel according to claim 1, whereby the first and or second fibrous mat has an area weight of between 100 and 900 gsm.

8. The sandwich panel according to claim 1, whereby the core layer is a spacer board with a honeycomb, corrugated or tubular grit structure, or a closed cell foam structure.

9. The sandwich panel according to claim 1, whereby the core material is made from plastic, a natural material, an inorganic material, a combination of natural fibers and a resin, or a metal.

10. The sandwich panel according to claim 1, whereby the core layer is a honeycomb board with a cell diameter of between 4 and 10 mm or preferably between 6 and 8 mm.

11. The sandwich panel according to one of claim 1, whereby the core material is polyester closed cell foam board with a density of between 60 and 200 kg/m3.

12. The sandwich panel according to claim 1, whereby the thickness of the core layer is between 2 and 30 mm or 5 and 20 mm.

13. The sandwich panel according to claim 1, further comprising at least on one surface of the panel raised protrusions in the skin layer formed, like a raised pattern in the form of knobs, waves or embellishments, surface patterning similar to wood or leather graining, stiffening ribs, or beams.

14. The sandwich panel according to claim 1, further comprising additional layers laminated to at least one surface fully or locally, chosen from a tufted carpet, a nonwoven carpet, knitted layer, foil layer, foamed, spray or RIM skin layer, a foil, a film, a scrim layer, a logo, or anti-sliding pad.

15. The sandwich panel according to claim 1, further comprising an in-mold coating of at least one surface skin layer fully or partially covering the surface comprising one of an aesthetic coating, a coating impervious to water and/or grease, a thermal conductive coating, an electro conductive coating, or electro-magnetic shielding coating.

16. A process for the production of the sandwich panel according to claim 1: wetting a sandwich stack comprising at least one core layer and two fibrous layers in contact with the surfaces of the core layer on both sides with a polyurethane forming mixture which includes a foam stabilizer; placing the wetted sandwich stack in a compression mold; closing the mold and maintaining the mold at a temperature in the range between 40° and 200° C. to mold the part and to harden the polyurethane foam forming mixture and thereby forming a molded part, whereby the polyurethane is embedding the fibers and binding to the core layer; removing the molded article from the mold, characterized in that the sandwich stack further comprises at least a polyether polyurethane slab foam layer covering the outer surface of a fibrous layer, and whereby on that side the polyurethane mixture is applied on top of the polyether polyurethane foam surface and the polyurethane penetrates the slab foam layer as well as the fibrous layer and binding to the core layer, and whereby during the compression of the stack in the close mold a polyurethane skin is formed on top of the polyether polyurethane foam surface not in contact with the fibrous layer.

17. A method of using of the sandwich panel according to claim 1 as a load floor panel, a main floor panel for a passenger compartment, as roof module, bonnet, tailgate module, door module, floor panel module, parcel shelf, spare wheel cover, interior trim component, as a battery or battery pack cover, as a computer or battery box, or as a partitioning panel.

18. The sandwich panel according to claim 6, wherein the inorganic fibers comprise glass, carbon, basalt or aramid fibers; wherein the synthetic fibers comprise polyester; wherein polyolefin comprises polyethylene, polypropylene, or polyamide fibers; wherein the organic regenerated fibers comprise viscose, rayon, or modal fibers; wherein the natural fibers comprise hemp, flax, kenaf, bamboo or other cellulose fibers; and wherein the animal fibers comprise wool fibers.

19. The sandwich panel according to claim 9, wherein the plastic comprises polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide, polypropylene, polyethylene, a polylactic based material, Polyether ether ketone (PEEK), polycarbonate; wherein the natural material is paper or cardboard; wherein the inorganic material comprises an aramid.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0064] FIG. 1 Schematic figure of a car with an example of a part that can be produced according to the invention.

[0065] FIGS. 2 and 3 Schematic layout of the material layers in the final product.

[0066] FIG. 4 schema of the production of a part according to the invention.

DETAILED DESCRIPTION

[0067] FIG. 1 shows partially a personal vehicle back area 20, with a load floor that might be produced according to the invention. The load floor can be designed with at least one surface according to the invention, preferably with both surfaces according to the invention. Preferably the load floor is designed such that it can be reversed between an A side and a B side, being the opposite surfaces on the load floor panel, whereby one side might be equipped with a carpet type surface for instance a tufted carpet or a nonwoven carpet and the other side might have a bare surface according to the invention.

[0068] FIGS. 2 and 3 are showing example cross sections of sandwich panels (1) according to the invention with a honeycomb core layer (2) with chambers 3 which form open channels between both surfaces of the core layer. The walls of the channels can be formed from different materials such as but not limited to paper, cardboard or plastics material like polyolefin, polypropylene, polyethylene or polyester based materials as well as composite materials made of natural fibers and thermoplastics.

[0069] Although the core layer depicted is a honeycomb other grid forms might be used such as tubular, corrugated or closed cell foam.

[0070] The core material is preferably covered on both sides with a fibrous reinforcement layer (7) to form a sandwich, although the covering layers between the sides might vary, they must be even in their tensile strength performance under thermal conditions to prevent warping of the part.

[0071] At least on one side coverage (4) might consist of at least a fibrous reinforcement layer (7) and a resilient polyether slab foam layer (6) which are penetrated and engulfed by polyurethane foam. The polyurethane foam will form a skin layer (5) on top of the polyether polyurethane foam layer, be pressed inside the polyether polyurethane foam layer and inside the fibrous layer and a small amount will finally bulge inside the top of the open channels of the honeycomb core material (8), by doing so it will also bind the core layer and the other layers together. Due to the forming in a compression mold the coverage structure is compressed to form a dense skin and an overall strong structural layer.

[0072] The thus bound layers form together a strong sandwich that can bear high loads on its surface without bending or sagging substantially.

[0073] The construction of FIG. 2 can be used in many different applications and due to the use of the polyether polyurethane foam on one or both sides it is possible to use the board without any covering layer. The fibrous structure of the fibrous mats particularly when they are glass fiber mats is no longer visible and possible damaging of the surface will no longer free the fiber content.

[0074] Part of the use of the board as load floor or flooring panel in the passenger compartment, it can now also be used as a floor panel in a frunk—a front storage space in an electric vehicle.

[0075] It is also possible to use the panel as a battery cover or computer panel or box, as the material is very light in weight but has a high stiffness and impact protection. If needed the panel can be locally further enforced with metal beams or plates to further enhance the crash protection. It is also possible to introduce crash break lines within the core to enable crash zones if needed.

[0076] FIG. 3 also shows a preferred example of a panel according to the invention build up as a reversed load floor, for instance like depicted in FIG. 1. The main layout and numbering is the same as in FIG. 2. However here the reversible load floor has an A-Surface (A) and a B-surface (B) both surfaces good enough to form an A quality surface but with different functions.

[0077] The A-surface in this case is the classical carpet surface with a tufted carpet (17) laminated on the molded part.

[0078] The B-surface is now formed by the dense polyurethane skin whereby the surface contains embellishments in the form of a raised pattern on the surface of the part with knobs (14) and ribs (15) mainly filled by the polyurethane skin material. In addition the surface contains a raised rim (16) at the edge of the part whereby the raised rim is mainly formed by the polyether polyurethane foam layer (6 not to scale) that rebounds pushing the polyurethane foam (5 and 5′) back into the recess in the mold, in addition the foam further fills the space forming a dense foam (5′) and even denser skin (5) on the foam resulting in a durable rim.

[0079] FIG. 4 is schematically showing the main steps in a preferred production process for the sandwich panel according to the invention with step

[0080] Wetting of the material layers with the polyurethane mixture on both sides (100) in particular by putting the materials 1 in order underneath or opposite one or more polyurethane spray heads 12 that can move in relation to the surface to be covered. The polyurethane may be mixed and dosed immediately before spraying for instance using a first dosing system for the isocyanate (9) and a second dosing system for the polyol (10) into a mixing unit 11. Additives might be added to the stock or directly to the mixing unit;

[0081] Transferring the thus wetted material stack inside a heated mold (200) with a first and second mold half 13a and b, that can be closed together to form the final part;

[0082] Thermo-compression molding the part (300) by closing the mold and keeping it closed under pressure. The heat of the mold will (further) activate the polyurethane mixture creating a foam pressure that will help spreading the mixture through the layers as well as forming a skin on the surface of the part;

[0083] Unmolding the part (400).

[0084] After the unmolding additional surface layers like a carpet layer can be put on top of at least one surface to form a surface with a nice soft surface. For instance a tufted or nonwoven carpet layer or a fabric, like a neoprene fabric might be used. Preferably a small recess is made in the panel to obtain a plain level with the top of the carpet surface when positioned.

[0085] As an additional step also other appliances can be attached to the part like for instance handles, hinges etc. depending on the part and function.