Low-Density Foam at Least Partially Covered with a Skin Material

Abstract

The present invention refers to a foam material with a low-density foam core wherein the foam core is at least partially covered with a skin material having a higher density than the foam core, which has a density of no more than 400 kg/m.sup.3 while the density of the skin material is at least 800 kg/m.sup.3.

Claims

1. A foam material with a low-density foam core, wherein the foam core is at least partially covered with a skin material, characterized in that a density of the skin material is higher than a density of the foam core and the density of the foam core is no more than 400 kg/m.sup.3, and wherein density of the skin material is at least 800 kg/m.sup.3.

2. The foam material according to claim 1, further characterized in that the density of the foam core is higher than 40 kg/m.sup.3.

3. Foam material according to claim 1, characterized in that an overall density of the foam material is less than 500 kg/m.sup.3.

4. The foam material according to claim 1, characterized in that the foam core is made of a polymer selected from the group consisting of polystyrene (PS), high-impact polystyrene (HIPS), polyethylene terephthalate (PET), polypropylene (PP), high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), styrene-butadiene blockcopolymer (SBS), styrene ethylene butylene copolymer (SEBS), and their blends.

5. The foam material according to claim 4, characterized in that the foam material is at least partially obtained from at least 20 wt.-% of a recycled polymer.

6. The foam material according to claim 1, characterized in that the density of the skin material is at least 1000 kg/m.sup.3.

7. The foam material according to claim 1, characterized in that the skin material is selected from the group consisting of polystyrene (PS), high-impact polystyrene (HIPS), polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), high-density polyethylene (HDPE), poly(p-phenylene oxide (PPO), polyvinylchloride (PVC), acrylonitrile butadiene styrene (ABS), styrene-butadiene blockcopolymer (SBS), styrene ethylene butylene copolymer (SEBS) as well as their blends.

8. The foam material according to claim 1, characterized in that the skin material is a solid material or a slightly foamed material.

9. The foam material according to claim 1, characterized in that the thickness of the skin material is 100 to 2000 m.

10. Foam material according to claim 1, characterized in that the foam material has a fire resistance of at least class E s1 d0, determined according to EN 13501-1.

11. The foam material according to claim 1, characterized in that the foam material has an E-modulus according to ISO 178 of at least 0.1 GPa.

12. The foam material according to claim 1, characterized in that the foam material has a flexural strength according to ISO 178 (23 C., 50% RH, 20 mm/min) of at least 1.5 MPa.

13. The foam material according to claim 1, characterized in that the surface of the foam core covered by the skin material shows no visible impact in the Wegner test at 15 Newton according to DIN 53799.

14. The foam material according to claim 1, characterized in that the foam material has a Shore 0 hardness of at least 40, determined according to ASTM D 3240.

15. The foam material according to claim 1, characterized in that the foam material has a Shore D hardness of at least 60, determined according to DIN 53505.

16. A product containing the foam material according to claim 1, the product comprising thermal insulation, sound insulation, a sealing material, a damping material for the purpose of weakening or canceling oscillations or vibrations, a stiffening material, a structural element, a door seal, a window seal, a faade seal, a product for decorative purposes, or a base board.

Description

EXAMPLES

[0039] The present invention will be described in more detail with reference to the following examples which by no means are to be understood as limiting the scope and spirit of the present invention.

[0040] Several samples of inventive foam material having a thickness of 12.8 mm and a width of 38 mm were prepared using a foam core of GPPS foamed at a temperature of 155 C. with a density of 200 kg/m.sup.3. The samples were covered with a skin of high-impact polystyrene of different thickness by co-extruding the foam core and skin material at a temperature of 170 C. and the mechanical properties were analyzed. For comparison, the properties of a low-density foam of GPPS having a density of 200 kg/m.sup.3 (Comp. 1) and 400 kg/m.sup.3 (Comp. 2), respectively, without skin cover are provided.

Methods

[0041] The density was determined according to DIN 53479

[0042] The Shore D hardness was determined according to DIN 53505.

[0043] The E-modulus was determined according to ISO 178.

[0044] The flexural strength was determined according to EN 12089.

[0045] The inventive foam materials were prepared by extrusion. As can be seen from the data provided in Table 1, the foam material according to the present invention (Ex.-1, Ex.-2 and Ex.-3) provided an excellent combination of properties with an improved Shore D hardness compared to foams without skin material (Comp. 1 and Comp. 2), while at the same maintaining the other mechanical properties.

TABLE-US-00001 TABLE 1 Skin overall Flexural thickness density E-Modulus Strength Example [m] [kg/m.sup.3] Shore D [MPa] MPa] Ex .-1 500-630 244 67 664 11.9 Ex .-2 390-400 230 58 613 11.6 Ex .-3 440-500 236 63 655 12.1 Comp. 1 206 27 446 8.4 Comp. 2 385 55 770 14.2

[0046] Further, the inventive foam materials showed no visible dent after the Wegner Test according to DIN 53799, while the foams used in Comp 1 and Comp 2 clearly showed the place of impact at 15 Newton. The results of the Wegner Tests are shown in FIG. 1 with pictures A and B depicting common foams of 200 kg/m.sup.3 and 400 kg/m.sup.3, respectively, without a cover, while pictures C and D show examples of the inventive foam material. As can be clearly seen, almost no impact mark is visible in case of the inventive foam material.