Metal Polymer Laminate Structure

Abstract

Disclosed herein are a metal-polymer laminate structure having an enhanced flame protection function as well as a method for preparing the same. The metal-polymer laminate structure includes a metallic layer, at least one polymeric layer provided on the metallic layer, and a backing layer provided on the at least one polymeric layer. The at least one polymeric layer includes an intumescent material, and a first functional layer is interposed between the metallic layer and the at least one polymeric layer. The first functional layer is a thermoplastic layer constructed from a material selected from polyamide, thermoplastic polyurethane, hotmelts, preferably polyamides such as PA6, PA6/6.36, PA6/66, PA12, PA6.12, PA6.10, PA6I/6T, copolymers of caprolactam or lauryllactam, thermoplastic polyurethane, and polyether block co-polyamides or combinations thereof.

Claims

1. A metal-polymer laminate structure, comprising a metallic layer, at least one polymeric layer provided on the metallic layer, and a backing layer provided on the at least one polymeric layer, wherein the at least one polymeric layer comprises an intumescent material, wherein a first functional layer is interposed between the metallic layer and the at least one polymeric layer, and wherein the first functional layer is a thermoplastic layer which comprises a material selected from the group consisting of polyamide, thermoplastic polyurethane, hotmelts, preferably polyamides such as PA6, PA6/6.36, PA6/66, PA12, PA6.12, PA6.10, PA6I/6T, copolymers of caprolactam or lauryllactam, thermoplastic polyurethane, and polyether block co-polyamides or combinations thereof.

2. The metal-polymer laminate structure according to claim 1, wherein the polymer of the at least one polymeric layer comprises at least one material selected from the group consisting of polyamide, polyvinylchloride, thermoplastic polyurethane, polyethylene, copolymers of polyethylene and α-polyolefins, copolymers of polyethylene and acrylic acid derivatives, polypropylene, polyurethane, melamine formaldehyde resins, polybutylene terephthalate, polyethylene terephthalate, polyoxymethylene, ethylene-vinyl acetate, low melting polyamides, PA12, PA6/6.36, polyether block polyamides, copolymerisates of polyether diamines and aliphatic dicarboxylic acids and/or lactams, copolymerisates of polyether diamines and aliphatic dicarboxylic acids and/or caprolactam, copolymerisates of polyether diamines and aliphatic dicarboxylic acids and/or lauryllactam, copolymerisates of aliphatic diamines and aliphatic dicarboxylic acids, polycondensates of lactams, copolymerisates of lactams and/or aliphatic dicarboxylic acids, and aliphatic diamines or combinations thereof.

3. The metal-polymer laminate structure according to claim 1, wherein the metallic layer is in substance-locking contact with the at least one polymeric layer.

4. The metal-polymer laminate structure according to claim 1, wherein the intumescent material comprises at least one material selected from the group consisting of thermally expandable graphite, ammonium polyphosphate, sodium silicate-hydrate, and combinations thereof.

5. The metal-polymer laminate structure according to claim 1, wherein the backing layer is a second metal layer or a thermoplastic polymer layer.

6. The metal-polymer laminate structure according to claim 1, wherein the metal-polymer laminate structure is processable by plastic metal working techniques.

7. A method for preparing a metal-polymer laminate structure according to claim 1, comprising the steps of a) providing a metallic layer, aa) providing a first functional layer on the surface of the metallic layer before carrying out step b, b) providing at least one polymeric layer onto the metallic layer, c) providing a backing layer onto the at least one polymeric layer, thereby attaining a pre-laminate structure, d) pressing the pre-laminate structure at elevated temperature, and e) obtaining the metal-polymer laminate structure.

8. The method according to claim 7, wherein step d) is carried out at a temperature at which the intumescent material starts intumescing.

9. The method for manufacturing a moulded part, comprising the steps of i) providing a metal-polymer laminate structure according to claim 1, ii) processing the metal-polymer laminate structure by at least one of a plastic metal working technique, and iii) obtaining the moulded part with a metal-polymer laminate structure.

10. The method according to claim 9, wherein the plastic metal working technique includes deep-drawing.

11. A method of using a metal-polymer laminate structure according to claim 1 as an active thermoshield for battery housings and/or for triggered heat isolation and/or for active burn-through protection.

12. A composite component, comprising a metal-polymer laminate structure according to claim 1, a polymeric foam layer provided on the backing layer, said backing layer being covered by at least one third functional layer, and a second solid layer having a density of more than 1000 g/l, which is covered by at least one fourth functional layer, the at least one fourth functional layer being in contact with the polymeric foam layer, wherein the polymeric foam layer has a density of 20 g/l to less than 1000 g/l.

13-15. (canceled)

Description

[0098] FIG. 1 depicts a schematic view of the metal-polymer laminate structure 1 according to an embodiment of the invention,

[0099] FIG. 2 depicts a laboratory set-up for testing the invented metal-polymer laminate structure 1,

[0100] FIG. 3 is a picture of comparative examples, a reference and inventive examples of the experiments,

[0101] FIG. 4 is a picture of a cross-section of a metal-polymer laminate structure 1 according to the present invention,

[0102] FIG. 5 shows a schematic drawing of a burn-through experiment and

[0103] FIG. 6 shows a graph of a temperature development vs. duration of flame exposure.

[0104] In FIG. 1 a schematic overview of the metal-polymer laminate structure 1 according to the present invention in a particular embodiment is given. Starting from below, a metallic layer 101 is depicted on which a first functional layer 107 is provided in order to enhance the joint between the metal layer 101 and the polymeric layer 103. On top of the structure a backing layer 105 is shown which also comprises a functional backing layer 109 in order to enhance the joint between the backing layer 105 and the polymeric layer 103.

[0105] As mentioned above, the backing layer 105 may be a thermoplastic polymer layer or a second metallic layer. In case of a thermoplastic polymer layer the functional backing layer 109 can be omitted.

[0106] In FIG. 2 a scheme of a laboratory set-up for a flaming test is given, wherein below a heat source H is shown. On top of a carrier C the invented metal-polymer laminate structure 1 is arranged. What is not shown is an aperture within the carrier C on which the invented metal-polymer laminate structure 1 is arranged in order to allow the flame of the heat source H to directly expose the invented metal-polymer laminate structure 1. On top of the metal-polymer laminate structure 1 a sensor S is arranged in order to monitor the temperature on the rear side of the invented metal-polymer laminate structure 1, this is on the opposite side of the flame of the heat source H.

[0107] In FIG. 3 comparative examples, a reference and inventive examples and are shown which are described in more detail below. Laminate I and laminate II are comparative examples with common and commercially available shielding laminate materials. The reference is a simple steel plate. Laminate III and laminate IV are two specific embodiments of the invented metal-polymer laminate structure (1).

[0108] In FIG. 4 a cross-section picture of laminate IV as a particular embodiment of the metal-polymer laminate structure 1 according to the invention is shown. From this picture the intumesced polymeric layer 103 can be observed which although it has expanded, does not extraordinarily deform the metallic layer 101 and the backing layer 105 (here a second metallic layer).

[0109] In FIG. 5 a particular feature of the present invention is shown. Below again the heat source H is depicted. While flaming the metal-polymer laminate structure 1 according to this particular embodiment, the metallic layer 101 is burned-through such that the polymeric layer 103 containing the intumescent material is directly exposed against the flame. Due to this heat exposure the intumescing material starts intumescing and swells out of the burned-through hole of the metallic layer 101. Due to a more or less continuous swelling of the intumescing material through this hole, most of the heat is absorbed such that the temperature at the backing layer 105, this is on the rear side of the metal-polymer laminate structure 1, can be kept relatively low.

[0110] Additional effects are observed in that by the expansion of the polymeric layer 103 in case of fire the heat transfer through the metal-polymer laminate structure 1 is remarkably reduced. Moreover, by the local burn-through of the metal layer 101 and the activation of the intumescent material, a reduction of pressure is caused by foaming from the surface towards the flame.

[0111] This has the particular advantages of no increase or undefined deformation of the invented metal-polymer laminate structure 1 in the event of fire. A prevention of completely burning through is prevented by the continuous swelling/foaming of the intumescent material in the direction of the flame/local damage.

[0112] In FIG. 6 a graph of the temperature development of the examples, the reference and the comparative examples during exposure to the flame is shown. The upper curve is a normal steel plate of 0.8 mm in thickness. After a few seconds the temperature on the rear side is between 600° C. and 700° C. Laminate I and laminate II are prepared from common and commercially available shielding materials, wherein different thicknesses of 0.8 mm and 1.6 mm are prepared. During the flame exposure, depending on the thickness, the temperature of approximately 400° C. for the 0.8 mm laminate I and a temperature of approximately 380° C. for the 1.6 mm laminate II are observed at the rear side. What can be observed during the test is that while intumescing the middle layer of the laminate I and laminate II specimen, the metal layers on both sides thereof are extremely deformed such that the whole part is no longer fulfilling its housing function.

[0113] On the other hand, laminate III and laminate IV as two particular embodiments of the present invention show the lowest temperature profiles at the rear side of the invented metal-polymer laminate structure 1 wherein laminate 4 keeps the temperature at the rear side below 250° C.

[0114] Therefore, both examples according to the present invention do not necessarily require a second metallic layer as the backing layer (105) but also a thermoplastic polymeric layer can be applied.

[0115] Experiments

[0116] Production of the invented metal-polymer laminate structure.sub.s

[0117] The polymers listed in Table 1 were compounded with a ZE 25A UXTI twin-screw extruder in the quantities shown in Table 1 to form cylindrical pellets of certain polymer compositions (PC). Then films were extruded from the resulting pellets (PC1 and PC2). The films have the thickness defined in Table 2 and a width of 40 cm. The quantities given in Tables 1 and 2 are each in weight-%. The expanded graphite contained in sheet 4 was obtained directly from Wolman (Exterdens FD, 1 mm). [0118] P1: polyamide 6 (Ultramid B24N from BASF SE) [0119] P2: PA6/6.36 (Ultramid Flex F29 from BASF SE) [0120] Co1: Lucalene A2540 D (Basell); ethylene/butyl acrylate copolymer [0121] Co2: Exxelor 1801 (Exxon Chemicals) maleic anhydride grafted ethylene/propylene copolymer [0122] Co3: ethylene/carboxylic acid copolymer (Luwax EAS 5 from BASF SE) [0123] A1: Irganox B 1171 2×20KG 4G [0124] A2: Talcum

TABLE-US-00001 TABLE 1 polymer compositions PZ1 PZ2 P1 [wt.-%] 59.1 P2 [wt.-%] 86.1 Co1 [wt.-%] 25 Co2 [wt.-%] 15 10 A1 [wt.-%] 0.5 0.5 A2 [wt.-%] 0.4 0.4

TABLE-US-00002 TABLE 2 sheets used sheet 4 sheet 1 sheet 2 sheet 3 (Exterdens FD) PZ 1 [wt.-%] 100 100 PZ 2 [wt.-%] 100 R1 [wt.-%] sheet 1000 400 400 1000 thickness [μm]

[0125] The sheets described in Table 2 are then consolidated with pretreated metal tapes in a heatable press to form the invented metal-polymer laminate structures. Metal tape and sheet are cut to the following dimensions: 300 mm×200 mm. The temperatures given in Table 3 were used. The sheets 1, 2 and 3 were pre-dried overnight with dry air at 80° C. First of all, scrims are produced, which are placed in the cold press together with a spacer in the respective target thickness. The press is closed with a contact pressure of 100 kN and heated to the target temperature given in Table 3. The temperature is held for 60 s, then the press is cooled to 50° C. and the laminate is removed.

[0126] The following metal tapes were used [0127] M1: Galvanized steel pre-treated with Gardobond X4543 (aqueous solution of phosphoric acid and acrylic acid solution, tradename of Chemetal GmbH), thickness 250 μm [0128] M2: aluminium tape pre-treated with Gardobond X4595 (aqueous solution of phosphoric acid and acrylic acid solution, tradename of Chemetal GmbH), thickness 300 μm

TABLE-US-00003 TABLE 3 invented metal-polymer laminate structures obtained lamination overall temperature thickness after ply 1 ply 2 ply 3 ply 4 ply 4 [° C.] pressing [mm] laminate I M1 sheet 1 M1 250 800 laminate II M1 sheet 2 M1 250 2000 laminate III M1 sheet 3 sheet 4 sheet 3 M1 200 2200 laminate IV M2 sheet 3 sheet 4 sheet 3 M1 200 1600

[0129] The invented metal-polymer laminate structures 1 obtained were subjected to a flame test. The invented metal-polymer laminate structures were flame treated on the front side (from below as shown in FIG. 2) with a Bunsen burner and the temperature on the rear side was measured with two thermal sensors. The temperature versus flame exposure time is plotted as an evaluation in FIG. 6. A galvanized body steel tape with a thickness of 0.8 mm serves as the reference)

[0130] The metal-polymer laminate structures embodied as laminates I, II, Ill, IV showed a strongly reduced heat transmission compared to the reference. The metal-polymer laminate structures 1 containing expanded graphite showed the lowest heat transmission. The metal-polymer laminate structures embodied as laminates I+II deform strongly during the flame treatment. The metal-polymer laminate structure 1 embodied as laminate IV4 showed an interesting property: The metal layer burned through at the point of the flame treatment, which means that no pressure could build up in this metal-polymer laminate structure 1 which would lead to deformation. The expanded graphite in the polymeric layer 103 expanded during the flame treatment and prevented the passage of heat. Partially expanded graphite emerged at the flame point from which it was immediately replaced by expanded graphite reprinted from the inside of the laminate.

REFERENCE SIGNS

[0131] 1 metal-polymer laminate structure [0132] 101 metallic layer [0133] 103 polymeric layer [0134] 105 backing layer [0135] 107 first functional layer [0136] 109 backing functional layer [0137] 1000 composite component [0138] 1003 third functional layer [0139] 1005 polymeric foam layer [0140] 1007 fourth functional layer [0141] 1009 second solid layer [0142] C carrier [0143] H heat source [0144] S sensor