LIGHT WEIGHT FIBER REINFORCED POLYPROPYLENE COMPOSITION

Abstract

The invention is related to a new fiber reinforced polypropylene composition with reduced weight and maintained mechanical properties, as well as articles formed therefrom.

Claims

1. A fiber reinforced polymer composition comprising (a) from 10 to 85 wt %, based on the total weight of the fiber reinforced polymer composition, of a polypropylene (PP), (b) from 12.5 to 53 wt %, based on the total weight of the fiber reinforced polymer composition, of fibers (F), (c) from 2 to 12 wt %, based on the total weight of the fiber reinforced polymer composition, of glass bubbles (GB), and (d) from 0.5 to 5 wt.-%, based on the total weight of the fiber reinforced polymer composition, of a polar modified polypropylene (PMP) as coupling agent.

2. A fiber reinforced polymer composition according to claim 1, wherein the polypropylene (PP) comprises a propylene homopolymer (H-PP) and/or a propylene copolymer (C-PP).

3. A fiber reinforced polymer composition according to claim 1 or 2, wherein the polypropylene (PP) comprises a heterophasic propylene copolymer (HECO) comprising (a) a polypropylene matrix (M) being a propylene homopolymer or a propylene copolymer, and (b) an elastomeric propylene copolymer (E) comprising units derived from propylene and ethylene and/or C4 to C20 -olefin.

4. A fiber reinforced polymer composition according to claim 3, wherein the heterophasic propylene copolymer (HECO) has (a) A melt flow rate MFR2 (230 C.), measured according to ISO1133, in the range of 1.0 to 50 g/10 min, (b) A comonomer content in the range of 3.0 to 25 wt %, based on the total heterophasic propylene copolymer (HECO), and (c) A xylene soluble content (XCS) in the range of 10 to 50 wt %, based on the total heterophasic propylene copolymer (HECO).

5. A fiber reinforced polymer composition according to any one of the preceding claims, wherein the fiber reinforced polymer composition further comprises up to 20 wt %, based on the total weight of the fiber reinforced polymer composition, of an elastomeric polymer impact modifier (IM).

6. A fiber reinforced polymer composition according to any one of the preceding claims, wherein the fibers (F) have an average diameter of from 8 to 20 m and an aspect ratio of 125 to 650.

7. A fiber reinforced polymer composition according to any one of the preceding claims, wherein the fibers (F) are selected from the group consisting of glass fibers, metal fibers, mineral fibers, ceramic fibers and mixtures thereof.

8. A fiber reinforced polymer composition according to any one of the preceding claims, wherein the glass bubbles (GB) have an average diameter of 10-50 m.

9. A fiber reinforced polymer composition according to any one of the preceding claims, wherein the polar modified polypropylene (PMP) is a propylene copolymer grafted with maleic anhydride, preferably the propylene copolymer grafted with maleic anhydride comprises ethylene as comonomer units.

10. An automotive article comprising the fiber reinforced polymer composition according to any one of the preceding claims.

11. A foamed article comprising the fiber reinforced polymer composition according to any one of the claims 1 to 9.

Description

EXAMPLES

[0096] The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

1. Measuring Methods

[0097] The total filler content is measured and calculated by incineration of the samples according to ISO 3451-1:2008 with the deviation from the norm of 550C in a microwave oven.

[0098] Density was measured on injection moulded specimen by pycnometer method according to ISO 1183-1:2004.

[0099] MFR2 (230 C.) is measured according to ISO 1133 (230 C., 2.16 kg)

[0100] Xylene cold soluble (XCS): Content of xylene cold soluble (XCS) is determined at 25 C. according to ISO 16152, first edition; 2005-07-01. The part which remains insoluble is the xylene cold insoluble (XCI) fraction.

[0101] Intrinsic viscosity is measured according to DIN ISO 1628/1, October 1999 (in Decalin at 135 C.).

[0102] The maximum force (F.sub.max) and energy to 8 mm deflection were determined in puncture impact testing at a testing speed of 4.4 m/s and room temperature (23 C./50% RH). In order to assess real part and injection molding conditions as well as typical impact conditions, a finished part (bracket/console) was used for testing. The part was positioned on two line supports (span length of 35.5 cm) and impacted in the center with an impactor with a hemispherical head with 20 mm diameter. Besides of support and specimen type, testing followed ISO 6603-2. The force-deflection curve was recorded and two parameters were used to compare different material compositions which are: [0103] maximum force (F.sub.max) in N [0104] as no fracture or puncture of the parts occurred, the energy to 8 mm deflection in J was calculated

2. Examples

[0105] The following inventive example IE1 and IE2 and comparative example CE1 were prepared by compounding on a 27 mm co-rotating twin-screw extruder. The following process parameters were used: [0106] throughput of 10-20 kg/h [0107] barrel temperatures of 200 C.

[0108] Injection moulded compact parts (bracket/console) are prepared for the mechanical test. Also, foamed parts with the same setting and dimensions were produced by the Mucell process on a KM650-4300GX injection moulding machine with the following key process parameters:

[0109] Barrel temperatures of 240 C.

[0110] SCF (Super Critical Fluid) Content: 0.25 to 0.32%

[0111] Table 1 summarizes the composition of the inventive and comparative examples and their properties

TABLE-US-00001 TABLE 1 Overview of composition and mechanics for inventive and comparative examples IE 1 IE 2 CE 1 PP1 [wt.-%] 58.5 66.5 66.5 GF [wt.-%] 32 28 32 GB [wt.-%] 8 4 0 PMP [wt.-%] 1.5 1.5 1.5 Density [g/cm.sup.3] 1.06 1.07 1.14 Total Filler Content [wt.-%] 39.5 31.9 31.7 Average weight of g/single 851 839 892 compact part part Average weight of g/single 808 792 850 5% foamed part part F.sub.max of compact part [N] 557 525 570 F.sub.max of 5% foamed part [N] 539 481 449 Energy to 8 mm deflection [J] 3.28 3.08 3.41 (compact part) Energy to 8 mm deflection [J] 3.24 2.89 2.66 (5% foamed part)

[0112] PP1 in both inventive examples and comparative examples is a commercial product EE013AE of Borealis AG, which is a heterophasic propylene copolymer. The basic properties of PP1 is showed in Table 2.

[0113] GF is the commercial product Johns Manville ThermoFlow CS EC 13 636 4 mm. Having a filament diameter of 13 m and a strand length of 4 mm

[0114] GB is the commercial product 3M IM16K Hi-Strength Glass Bubbles with crush strength of 110 MPa, diameter 20 m, available from 3M company (USA).

[0115] PMP is the commercial product Exxelor P01020 which is a maleic anhydride (MAH) functionalized polypropylene commercially available from Exxon Mobil (USA) having a density of 0.9 g/cm3, an MFR2 (230 C./2.16 kg) of 430 g/10 min and a MAH content of 1.0 mol %.

TABLE-US-00002 TABLE 2 Properties of PP1 MFR [g/10 min] 10.5 MFR of XCI [g/10 min] 50 XCS [wt %] 29.0 C2 total [wt %] 15.5 C2 in XCS [wt %] 39.0 IV of XCS [dl/g] 3.0 Flexural Modulus [MPa] 770

[0116] It can be gathered from Table 1 that the inventive examples IE1 and IE2 comprising glass bubbles in combination with glass fibers in a polypropylene matrix has well-improved mechanical properties for foamed articles, at reduced density and thus at lighter weight.