COMPOSITION BASED ON RECYCLED POLYETHYLENE FROM CABLE WASTE

Abstract

The invention is related to a polyethylene composition characterized in that it comprises a base resin and an inorganic mineral filler which is present in the composition in an amount of 1 to 50 wt % in respect to the weight of composition, wherein said base resin comprises: a) a first crosslinked polyethylene (PEX) having a gel content (measured according to ASTM D 2765:2006) in the range of 5% to 80% in respect to the weight of crosslinked polyethylene (PEX), said crosslinked polyethylene (PEX) being obtained from recycled wastes and b) a second polyethylene (PE) selected from virgin polyethylene and recycled polyethylene, or mixtures thereof. The invention is further related to a process for production of said polyethylene composition, and use of the polyethylene composition.

Claims

1. A polyethylene composition comprising a base resin and an inorganic mineral filler which is present in the composition in an amount of 1 to 50 wt % in respect to the weight of composition, wherein said base resin comprises: a) a first crosslinked polyethylene (PEX) having a gel content (measured according to ASTM D 2765:2006) in the range of 5% to 80% in respect to the weight of crosslinked polyethylene (PEX), said crosslinked polyethylene (PEX) being obtained from recycled waste, and b) a second polyethylene (PE) selected from virgin polyethylene and recycled polyethylene, or mixtures thereof.

2. Polyethylene composition according to claim 1, wherein the weight ratio of PEX: PE in the base resin is in the range of from higher than 10:90 to 90:10.

3. Polyethylene composition according to claim 1, wherein the crosslinked polyethylene (PEX) is obtained from recycled waste wherein the waste is selected from electrical cable waste.

4. Polyethylene composition according to claim 1, wherein the crosslinked polyethylene (PEX) has a chlorine content in the range of 300 to 2000 ppm measured with X-ray fluorescence analysis (XRF).

5. Polyethylene composition according to claim 1, wherein the crosslinked polyethylene (PEX) has: c) a copper content in the range of 20-500 ppm and/or d) an aluminum content in the range of 500-15000 ppm, measured with X-ray fluorescence analysis (XRF).

6. Polyethylene composition according to claim 1, wherein the second polyethylene (PE) is selected from virgin high density polyethylene (vHDPE), virgin medium density polyethylene (vMDPE), recycled high density polyethylene (rHDPE), recycled medium density polyethylene (rMDPE) and the mixtures thereof.

7. Polyethylene composition according to claim 1, wherein the inorganic mineral filler is selected from CaCO.sub.3 and Talc.

8. Polyethylene composition according to claim 1, wherein the composition has a gel content in the range of 10 to 40 wt % in respect to the weight of the base resin as measured according to ASTM D 2765:2006.

9. Polyethylene composition according to claim 1, wherein the composition has a flexural modulus determined according to ISO 178 of more than 840 MPa.

10. Polyethylene composition according to claim 9, wherein the composition additionally has an elongation at break determined according to ISO 527-2 of more than 2%.

11. Polyethylene composition according to claim 9, wherein the composition has a tensile stress at break determined according to ISO 527-2 of more than 13 MPa.

12. Polyethylene composition according to claim 9, wherein the composition has a yield stress determined according to ISO 527-2 of more than 15 MPa.

13. Process for producing a polyethylene composition according to claim 1, wherein the said process comprising the steps of: a) feeding the ingredients into the inlet hopper of a compounding unit; b) compounding the ingredients which compounding is carried out by homogenizing the ingredients fed into the inlet and raising the temperature to above the melting point of the main thermoplastic polymer ingredient, obtaining a mixture compound; and c) optionally cooling down the said mixture compound and pelletizing.

14. Process for producing a shaped article comprising a polyethylene composition according to claim 1, wherein the said process comprises the additional step of shaping the said polyethylene composition with a moulding step.

15. (canceled)

Description

EXAMPLES AND MEASURING METHODS

[0060] 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

[0061] Gel Content (wt %): is measured according to ASTM D2765-90 using a sample consisting of the polyethylene composition of the invention (Method A, decaline extraction).

[0062] X-ray Fluorescence analysis (XRF): The elemental content was analysed by wavelength dispersive XRF (AXS S4 Pioneer Sequential X-ray Spectrometer supplied by Bruker). The pellet sample was pressed to a 3 mm thick plaque (150? C. for 2 minutes, under pressure of 5 bar and cooled to room temperature). Generally, in XRF method, the sample is irradiated by electromagnetic waves with wavelengths 0.01-10 nm. The elements present in the sample will then emit fluorescent X-ray radiation with discrete energies that are characteristic for each element. By measuring the intensities of the emitted energies, quantitative analysis can be performed. Here, the analysis has been done with a standard-free program where the 28 most common elements are detected and the concentrations of the detected elements are calculated based on a CH.sub.2 matrix.

[0063] Flexural modulus: is determined on compression molded sample according to ISO 178 at 23? C., the sample thickness is mentioned below in the sample preparation.

[0064] Tensile testing: Tensile stress and modulus for the examples 1E1-5, CE3-5 were determined on compression moulded specimens according to ISO 527-2 at 50 mm/min and 23? C., the sample thickness is mentioned below in the sample preparation. Tensile test for the examples 1E6 and CE1, 2, 6-8 was measured according to ISO 527-2 on injection moulded specimens as described in EN ISO 1872-2 (80?10?4 mm), wherein the crosshead speed for testing the modulus was 1 mm/min and crosshead speed for testing the tensile strength and elongations was 50 mm/min.

[0065] Test specimen produced as described in EN ISO 1872-2 (the produced test specimens were 10 multipurpose test specimen of type B according to ISO 3167).

[0066] Charpy impact test: The charpy notched impact strength (Charpy NIS) is measured according to ISO 179 1eA at 23? C. and ?20? C. respectively. The impact is measured on samples prepared from injection molded specimens as described in EN ISO 1872-2 (80?10?4 mm)

2. Examples

Base Resin

PEX:

[0067] PEX RECYCLATE 1MM: a crosslinked polyethylene which is entirely recycled post-consumer cable waste is in the form of granules smaller than 1 mm in diameter. The PEX has a gel content of about 50 wt %. Table 1 shows the analytical result of PEX RECYCLATE 1MM

TABLE-US-00001 TABLE 1 Elemental content determined by XRF analysis on three pressed 3 mm plaques. Zinc 48 ppm Titan 82 ppm Calcium 955 ppm Sulphur 125 ppm Silicon 316 ppm Aluminium 1450 ppm Magnesium 191 ppm Chlorine 389 ppm Cupper 59 ppm Iron 61 ppm Nickel <5 ppm Phosphorus <5 Chromium <5 Potassium <5 Vanadinium <5

PE:

[0068] HE3450: a virgin high density polyethylene bimodal copolymer, commercially available from Borealis with a melt flow rate (MFR2) of 0.5 g/10 min, according to ISO 1133 (190? C., 2.16 kg) and a density of 0.950 g/cm.sup.3.

[0069] KRUTENE-HD: a recycled high density polyethylene in the form of pellets, commercially available from KRUSCHITZ GMBH with a melt flow rate (MFR2) of 0.49 g/10 min, according to ISO 1133 (190? C., 2.16 kg), and density of 0.950 g/cm.sup.3.

Inorganic Filler

[0070] CALCITEC M/5: Calcium carbonate filler which had a weight average mean particle size D50 of 5.0 microns with only 1 wt % having a particle size of 19 micron or higher, and a purity of 99% CaCO.sub.3.

[0071] MISTRON 75-6 A: Talc filler which has a weight average mean particle size D50 of 4.0 microns with only 2 wt % having a particle size of 20 micron or higher and a purity of 98% Mg-silicate.

Compounding and Preparation of Injection Moulded and Compression Moulded Samples

[0072] The predetermined amount of PEX and PE was mixed with the inorganic filler in a Brabender 350E mixer with a roller element at a temperature of 180? C. for 10 min. The screw speed was 40 RPM. The equipment was purged with nitrogen during the homogenisation to minimise degradation.

[0073] Injection moulding: The test specimens for the examples 1E6 and CE1, 2, 6-8 were injection moulded using a machine Engel e-motion 310/55HL with a 35 mm screw at 210? C.

[0074] Compression moulding: The test specimens for the examples 1E1-5, CE3-5 were compression moulded. The raw materials were transferred to a compression moulding device to produce about 2-4 mm thick plates from which the samples were machined into the sample type specified for the particular test method, respectively. 2 mm thick samples were used for the tensile measurements and 4 mm thick samples were used for measurements in bending mode. Compression moulding conditions: 200? C. at low pressure for 10 minutes and for 5 minutes at 614 N/cm.sup.2 and cooling down at 15? C./min. Table 2 and Table 3 list the composition recipes and mechanical properties for six inventive examples 1E1 to 1E6 and eight comparative examples CE1 to CE8. The inventive examples show a surprisingly good combination of mechanical properties comparing to the CE2-8 examples and bring the mechanical properties closer to CE1.

TABLE-US-00002 TABLE 2 Composition recipe and mechanical properties of the inventive samples IE1 IE2 IE3 IE4 IE5 IE6 HE3450-H (0.950 g/cm.sup.3) KRUTENE-HD 30 45 30 45 60 80 (0.952 g/cm.sup.3) PEX RECYCLATE 30 30 45 30 30 10 1 MM CALCITEC M/5 40 25 MISTRON 75-6 A 25 25 10 10 sum 100 100 100 100 100 100 Stress at break (MPa) 13.2 14.7 14.9 19.6 18.0 11.2 Yield stress 15.4 17.8 15.7 20.6 18.5 Flexural modulus 1120 950 1040 1330 940 (MPa) EAB (%) 5.4 12.2 5.3 3.9 7.2 40.0 Charpy NIS 23? C. 20.1 (kJ/m.sup.2) Charpy NIS ?20? C. 4.4 (kJ/m.sup.2)

TABLE-US-00003 TABLE 3 Composition recipe and mechanical properties of the comparative samples CE1 CE2 CE3 CE4 CE5 CE6 CE7 CE8 HE3450-H 100 80 (0.950 g/cm.sup.3) KRUTENE-HD 55 80 60 100 (0.952 g/cm.sup.3) PEX RECYCLATE 1 MM 60 75 45 CALCITEC M/5 40 40 MISTRON 75-6 A 20 25 20 sum 100 100 100 100 100 100 100 100 Stress at break (MPa) 23.1 4.6 10.7 10.2 6.6 5.3 13.0 8.5 Yield stress 19.6 11.9 10.5 18.1 Flexural modulus (MPa) 820 590 400 620 EAB (%) 647.0 82.0 8.4 8.9 63.8 53.0 13.9 144.0 Charpy NIS 23? C. (kJ/m.sup.2) 56.0 34.2 8.0 16.5 18.0 Charpy NIS ?20? C. (kJ/m.sup.2) 16.9 10.4 3.9 5.8 4.0