POLYMER FOAM LAMINATE STRUCTURE

Abstract

The present invention relates to a polymer foam laminate structure (1), comprising—a first solid layer (101) having a density of more than 1000 g/l, which is covered by at least one first functional layer (103), —a polymeric foam layer (105) provided on the at least one first functional layer (103), —a second solid layer (109) having a density of more than 1000 g/l, which is covered by at least one second functional layer (107), the at least one second functional layer (107) being in contact with the polymeric foam layer (103), wherein the polymeric foam layer (105) has a density of 20 g/l to less than 1000 g/l. The present invention further pertains a method for preparing a polymer foam laminate structure (1) and a composite component (1000) inter alia comprising the polymer foam laminate structure (1).

Claims

1. A polymer foam laminate structure, comprising a first solid layer having a density of more than 1000 g/l, which is covered by at least one first functional layer, a polymeric foam layer provided on the at least one first functional layer, a second solid layer having a density of more than 1000 g/l, which is covered by at least one second functional layer, the at least one second 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, and wherein the at least one first functional layer and/or the at least one second functional layer comprises a polyamide selected from PA6, PA6/6.36; PA12, PA610, Pa6/66, PA6.12, or polyether block copolyamide.

2. The polymer foam laminate structure according to claim 1, wherein the polymeric foam layer has a softening point of 100° C. to 280° C.

3. The polymer foam laminate structure according to claim 1, wherein the polymeric foam layer is obtainable by: fusing of pre-foamed polymeric particles, or extruding a thermoplastic polymer in the presence of a blowing agent through a slot die, or loading a thermoplastic polymer above the softening temperature with a blowing agent in an autoclave, followed by expansion and moulding, or using a foam injection moulding machine.

4. The polymer foam laminate structure according to claim 1, wherein the polymeric foam layer comprises a polyamide, a thermoplastic polyurethane, polyether block copolyamide, polypropylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polyester/polylactide, polyether sulfones and mixtures thereof.

5. The polymer foam laminate structure according to claim 1, wherein the at least one first functional layer and/or the at least one second functional layer further comprises a homo polymer or a copolymer of ethylene and/or α-olefins and/or acrylic acid esters and/or maleic anhydride.

6. The polymer foam laminate structure according to claim 5, wherein the homo polymer or the copolymer is grafted with maleic anhydride.

7. The polymer foam laminate structure according to claim 1, wherein the at least one first functional layer and/or the at least one second functional layer have a thickness between 20 μm and 2000 μm.

8. The polymer foam laminate structure according to claim 1, wherein the first solid layer and/or the second solid layer is a metal layer, preferably having a thickness between 150 μm and 2000 μm.

9. The polymer foam laminate structure according to claim 1, wherein first solid layer and/or the second solid layer is a solid polymer layer, preferably having a thickness between 1 mm and 10 mm.

10. The polymer foam laminate structure according to claim 9, wherein the solid polymer layer as the first solid layer and/or the second solid layer comprises a polymeric material reinforced by carbon fibre, glass fibre, aramid fibre, basalt fibre, natural fibre, metal fibre, potassium titanate particles and mixtures thereof.

11. The polymer foam laminate structure according to claim 1, wherein the first solid layer is in force-locking contact with the at least one first functional layer and the second solid layer is in force-locking contact with the at least one second functional layer.

12. A method for preparing a polymer foam laminate structure, according to claim 1, comprising the steps of a1) providing the first solid layer, a2) providing the second solid layer, b1) providing the at least one first functional layer onto the first solid layer, b2) providing the at least one second functional layer onto the second solid layer, c) providing the polymeric foam layer onto the at least one first functional layer and beneath the at least one second functional layer, thereby attaining a pre-laminate structure, d) pressing the pre-laminate structure at elevated temperature and e) obtaining the polymer foam laminate structure.

13. A method for preparing a polymer foam laminate structure, according to claim 1, comprising the steps of a1) providing the first solid layer, b2) providing the at least one first functional layer onto the first solid layer, c1) providing prefoamed thermoplastic beads of the polymeric foam material for the polymeric foam layer, the thermoplastic beads having a raw density of 200 g/l to 400 g/l), d1) providing the polymeric foam layer by direct fusing of the prefoamed beads onto the at least one first functional layer with hot steam or heat irradiation and e) obtaining the polymer foam laminate structure.

14. Use of the polymer foam laminate structure according to claim 1 as an energy-absorbing device.

15. A composite component, comprising the polymer foam laminate structure according to claim 1, the at least one polymeric layer provided either on the first solid layer or on the second solid layer of the polymer foam laminate structure and a metallic layer provided on the at least one polymeric layer opposite of the polymer foam laminate structure, wherein the at least one polymeric layer comprises an intumescent material.

Description

[0106] Further aims, features, advantages and possible applications result from the following description of preferred embodiments not restricting the invention by means of the figures. All described and/or pictorially depicted features, on their own or in any combination, form the subject matter of the invention, even independently of their summary in the claims or their retrospective relationship. In the Figures

[0107] FIG. 1 depicts a schematic view of the polymer foam laminate structure 1 according to an embodiment of the invention,

[0108] FIG. 2 is a picture of examples and comparative examples regarding the polymer foam laminate structure 1,

[0109] FIG. 3 is a graph of a force-displacement curve for the examples and comparative examples of FIG. 2,

[0110] FIG. 4 is a graph of absorbed energies for the examples and comparative examples of FIG. 2,

[0111] FIG. 5a is a graph of a force-displacement curve for a test specimen “PA particle foam 13”,

[0112] FIG. 5b is a picture of the test specimen underlying the graph of FIG. 5a,

[0113] FIG. 6a is a graph of a force-displacement curve for a test specimen “TPU foam”,

[0114] FIG. 6b is a picture of the test specimen underlying the graph of FIG. 6a,

[0115] FIG. 7 is a picture of a testing setup with a test specimen according to the invention inserted, and

[0116] FIG. 8 is a graph comparing the bending work.

[0117] In FIG. 1 a schematic overview of the polymer foam laminate structure 1 according an embodiment of the invention is given. On the top and on the bottom both the first solid layer 101 and the second solid layer 109 are shown. Both these layers are provided with the at least one first functional layer 103 and the at least one second functional layer 107, respectively, towards the inner. In between, the polymeric foam layer 105 is arranged.

[0118] Experiments

[0119] Production of the Invented Polymer Foam Laminate Structures 1

[0120] 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. The resulting pellets (PZ1 and PZ2) were then extruded into films using a cast calander extruder. The films had a thickness of 400 μm and a width of 40 cm. The quantities given in Table 1 are each in weight-%. [0121] P1: Polyamid 6 (Ultramid B24N of BASF SE) [0122] P2: PA6/6.36 (Ultramid Flex F29 of BASF SE) [0123] Co1: low density ethylene/n-butylacrylate copolymer (Lucalen A2540 D of Basell) [0124] Co2: ethylene propylene copolymer, grafted with maleic anhydride_(Exxelor 1801 of Exxon Chemicals) [0125] A1: N, N′-1,6-hexanediylbis [3,5-bis-4-hydroxyphenylpropanamide] (Irganox B 1171 2x20KG 4G of BASF SE) [0126] 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 1 sheet 2 PZ 1 [wt.-%] 100 PZ 2 [wt.-%] 100 thickness sheet [μm] 400 400

[0127] The sheets described in Table 2 were then consolidated with pretreated metal tapes as the first and second solid layers 101, 109 in a heatable press to form laminates. Metal tape and sheet were cut to the following dimensions: 300 mm×200 mm. The temperatures given in Table 3 were used. Sheet 1 and sheet 2 were pre-dried overnight with dry air at 80° C. First of all, scrims are produced, which were placed in the cold press together with a spacer in the respective target thickness. The press was closed with a contact pressure of 100 kN and heated to the target temperature given in Table 3. The temperature was held for 60 s, then the press was cooled to 50° C. and the laminate was removed.

[0128] The following metal tapes and polymeric tapes were used as the first and second solid layers 101, 109: [0129] M1 galvanized steel pretreated with an aqueous solution of phosphoric acid and acrylic acid (Gardobond X4543 of Chemetal GmbH) via roll coating, thickness of the metal sheet: 250 μm [0130] M2 aluminium pretreated with an aqueous solution of phosphoric acid and acrylic acid solution (Gardobond X4595 of Chemetal GmbH) via roll coating, thickness of the metal sheet: 300 μm [0131] K1: injection-moulded tape (10 mm×10 mm×2 mm) made of polyamide PA6-GF35 (Ultramid B3EG7 sw 564 from BASF SE)

[0132] In particular, the first and second solid layers 101, 109 may be pre-treated with an adhesion promoter/primer based on polyacrylates or polymethacrylates, polyvinyl amines, phosphoric acids, polyphosphoric acid; copolymers of maleic acid and acrylic acid and/or methacrylic acids and/or ester of acrylic or methacrylic esters, copolymers of maleic and styrene, copolymers of ethylene and acrylic acid and/or methacrylic acids and/or esters of acrylic or methacrylic esters and/or maleic acid and polyvinylpyrrolidone, to ensure good bonding to the first and second functional layers 103, 107. The adhesion promoter is typically applied as aqueous solution via roll coating.

TABLE-US-00003 TABLE 3 laminates obtained overall thickness lamination after ply 1 ply 2 temperature pressing laminate 1 M1 sheet 1 250 400 μm laminate 2 M1 sheet 2 220 400 μm laminate 3 M2 sheet 1 250 450 μm laminate 4 M2 sheet 2 220 450 μm laminate 5 K1 sheet 1 250 2100 μm  laminate 6 K1 sheet 2 220 2100 μm 

[0133] The laminates described in Table 3 were pressed into polymer foam laminate structure (PFLS). The polymeric foam layers PSP1 to PSP3 mentioned below in Table 4 were used as the core layers. The side provided with the functional layer was laminated to the top and bottom side of the polymeric foam layers 105.

[0134] The polymeric foam layers can be produced with all fusing methods known to the expert. More precisely described is the production in an automatic moulding machine based on steam technology. But also water-free methods such as radio frequency fusing by the Kurz company or the Variotherm process by the Fox Velution company are conceivable.

[0135] As the pre-foamed polymeric foam layers comprising TPU the product Infinergy 100 HD of BASF SE was used.

[0136] The pre-foamed polymeric foam layers comprising PA were produced as follows.

[0137] A melt impregnation was carried out in an apparatus consisting of a twin-screw extruder, divided into eight zones of equal length (Z1 . . . Z8), of the company Leistritz with an 18 mm screw diameter and a length to diameter ratio of 40, a melt pump, a start-up valve, a melt filter, a perforated die plate and an underwater pelletizer.

[0138] Polyamides together with talcum in a polyethylene bag were mixed and were feed in the twin screw extruder via a dosage unit. In the ⅓ of the extruder the polyamide was melted. After approximately ⅓ of the length of the extruder, the propellant was pumped with the aid of isco pump (piston pumps of the firm Axel Semrau) and was injected into the extruder. In the remaining part of the extruder the polymer melt was cooled by means of the temperature control of the twinscrew extruder. The temperature of the polymer melt, when passing through the perforated plate, corresponded to the temperature set at zone 8. By means of the melt pump the pressure profile in the extruder was set in such a way (pressure-speed control) that the blowing agent was completely mixed into the polymer melt. In addition to setting the pressure profile in the twin screw extruder, the melt pump also serves to convey the blowing agent and pressed the polymer melt is through the following devices (the start-up valve, the melt screen and the perforated plate). The melt strand emerging through the perforated plate (1 hole with a diameter of 1 mm) was introduced into the underwater pelletizer with pressure to give expanded polyamine granules with a granule weight of approx. 3.5 mg. The total throughput of the extruder was kept constant at about 4 kg/h. The strand in the water box was cut by 6 blades attached to the blade ring. The blade ring rotates at about 3500 rpm, thereby producing expanded granulates with a granulate weight of 3.5 mg, which are transported by the water circuit from the perforated plate into the drier and are separated into a collecting container.

[0139] For preparing PSP1, PSP2 and PSP4, the following composition was applied:

TABLE-US-00004 PSP1 PSP2 PSP4 Polyamide (A) Polyamide 6 50 50 Polyamide 6I/6T Polyamide (B) Copolyyamide 6/6.36 50 50 100 Nucleating agent Talk 0.5 0.5 0.5 Blowing Agent Nitrogen (N.sub.2) 0.2 0.2 0.2 Carbon dioxide (CO.sub.2) 1.5 1.5 0.3 Water Iso-pentane

[0140] The pre-expanded particles were loaded into the cavity of a mould by injection with compressed air (cavity dimensions: 300 mm in length, 200 mm in width and 25 mm in height). A certain mm of crack filling is applied for compressed particles. The mould was installed in a moulding machine. Thereafter, the pre-expanded particles were moulded by supplying saturated steam into the cavity for certain seconds (cross steam heating), and subsequently supplying saturated steam into the cavity for certain seconds (autoclave steam heating) via thermal fusion of the pre-expanded particles. Cooling water was supplied into the cavity of the mould for certain seconds to cool the resultant shaped and welded product. Process conditions and properties of the particle foam mouldings are compiled in Table 4. [0141] PSP1: PA foam density 655 g/l, before pressing thickness: 10 mm before pressing [0142] PSP2: PA foam density 590 g/l, thickness 25 mm before pressing [0143] PSP3: TPU foam density 300 g/l, thickness 10 mm before pressing [0144] PSP4: PA foam density 230 g/l, thickness 10 mm before pressing

TABLE-US-00005 TABLE 4 polymeric foam layers used Particle Cross steam Autoclave Part density bulk Crack heating steam heating Water after drying density filling Time Press. Temp. Time Press. Temp. cooling 70° C. Example [g/L] [mm] [s] [bar] ° C. [s] [bar] [° C.] [s] for 16 h PSP1 368 5 8 4 144 20 4 144 40 655 PSP2 368 10 8 4 144 20 1.4 144 60 590 PSP3 142 0 13 1.8 115 40 1.8 115 60 300 PSP4 116 10 5 1.7 113 4 1.7 113 30 250

[0145] The polymer foam laminate structures described in Table 5 were produced by placing the layers listed in Table 5 in a hot press with a pressure of 10 kN and heating them to the lamination temperature given in Table 5. Polymer foam laminate structure (PFLS) were obtained with the respective total thickness shown in Table 5.

TABLE-US-00006 overall thickness lamination after ply 1 ply 2 ply 3 temperature pressing PFLS 1 laminate 1 PSP1 laminate 1 250 9 mm PFLS 2 laminate 1 PSP2 laminate 1 250 24 mm PFLS 3 laminate 2 PSP1 laminate 2 220 10 mm PFLS 4 laminate 2 PSP2 laminate 2 220 25 mm PFLS 5 laminate 3 PSP1 laminate 3 250 9 mm PFLS 6 laminate 3 PSP2 laminate 3 250 24 mm PFLS 7 laminate 4 PSP1 laminate 4 220 10 mm PFLS 8 laminate 4 PSP2 laminate 4 220 25 mm PFLS 9 laminate 3 PSP3 laminate 3 250 5 mm PFLS 10 laminate 4 PSP3 laminate 4 220 10 mm PFLS 11 laminate 5 PSP1 laminate 5 250 12 mm PFLS 12 laminate 5 PSP2 laminate 5 250 12 mm PFLS 13 laminate 6 PSP1 laminate 6 220 14 mm PFLS 14 laminate 6 PSP2 laminate 6 220 14 mm

[0146] In case of PFLS 2, a slight collapsing of the foam could be observed.

[0147] FIG. 2 gives a picture of examples and comparative examples regarding the invented polymer foam laminate structure 1. The test specimen designated “5_2” is a PA particle foam sandwiched between metal layers (i.e. sheet metal) and the test specimen designated “13_1” is a PA particle foam which was used as the polymeric foam layer 103, while test specimen designated “Inf_3” is a TPU foam sandwiched between metal layers (i.e. sheet metal).

[0148] For the examples and comparative examples of FIG. 2, a graph of a force-displacement curve is shown in FIG. 3. It can be seen that the test specimen 5_2 (PA particle foam+sheet metal) shows high energy absorption and high stiffness, while the test specimen 13_1 (pure PA particle foam (PA Particle Foam 5) without sheet metal) shows only a low stiffness and therefore a low energy absorption. On the other hand, the test specimen Inf_3 (i.e. (Infinergy+sheet metal) has a very low stiffness but still high elasticity and shows a good energy absorption.

[0149] FIG. 4 shows a graph of absorbed energies for the examples and comparative examples of FIG. 2. As already known from FIG. 3, the test specimen 13_1 is superior compared to test specimen 5_2.

[0150] In FIG. 5a, a graph of a force-displacement curve for a test specimen test specimen 5_2 is shown in more detail, while FIG. 5b is a picture of the test specimen underlying this graph. The curves give an idea of the variation in energy absorbtion of different, but similar samples.

[0151] In FIG. 6a, a graph of a force-displacement curve for a test specimen TPU foam is shown in more detail, while FIG. 6b is a picture of the test specimen underlying this graph.

[0152] In FIG. 7, a testing setup is shown in which a test specimen according to the invention of polyamide sandwiched with steel is tested. Compared to standard car body steel this invented test specimen has the highest bending work, as shown in FIG. 8. There is no delamination and the foam core is almost intact.

REFERENCE SIGNS

[0153] 1 polymer foam laminate structure [0154] 101 first solid layer [0155] 103 first functional layer [0156] 105 polymeric foam layer [0157] 107 second functional layer [0158] 109 second solid layer [0159] 1001 metallic layer [0160] 1003 polymeric layer