Heavy duty support

Abstract

A polymer composition comprising a blend of two or more high density polyethylenes: (A) a first high density polyethylene having a density of at least 940 kg/m.sup.3 and an MFR.sub.2 of 0.25 g/10 min or less; and (B) a second high density polyethylene having a density of at least 940 kg/m.sup.3 and an MFR.sub.2 of 1.0 g/10 min to 20 g/10 min; wherein said polymer composition has an MFR.sub.2 of 0.25 to 15 g/10 min and wherein the components (A) and (B) combined form at least 91 wt % of said polymer composition.

Claims

1. A polymer composition comprising: a blend of two or more high density polyethylenes comprising: a first high density polyethylene having a density of at least 940 kg/m.sup.3 and an MFR.sub.2 of 0.25 g/10 min or less; and a second high density polyethylene having a density of at least 940 kg/m.sup.3 and an MFR.sub.2 of from 1.0 g/10 min to 20 g/10 min, and wherein the second high density polyethylene is multimodal and comprises from 30 to 70 wt % of a lower Mw component and from 70 to 30 wt % of a higher Mw component; wherein said polymer composition has an MFR.sub.2 of from 0.25 to 15 g/10 min, and wherein the first high density polyethylene and the second high density polyethylene combined form at least 91 wt % of said polymer composition.

2. The polymer composition as claimed in claim 1, wherein the first high density polyethylene is multimodal.

3. The polymer composition as claimed in claim 1, wherein the polymer composition comprises less than 5 wt % of polypropylene.

4. The polymer composition as claimed in claim 1, wherein the first high density polyethylene forms from 10 to 70 wt % of the polymer composition and the second high density polyethylene forms from 30 to 90 wt % of the polymer composition.

5. The polymer composition as claimed in claim 1, wherein the density of the first high density polyethylene is from 945 to 965 kg/m.sup.3.

6. The polymer composition as claimed in claim 1, wherein the MFR.sub.5 of the first high density polyethylene is from 0.1 to 0.9 g/10 min.

7. The polymer composition as claimed in claim 1, wherein the density of the second high density polyethylene is from 955 to 965 kg/m.sup.3.

8. The polymer composition as claimed in claim 1, wherein the MFR.sub.2 of the second high density polyethylene is from 2.0 to 10.0 g/10 min.

9. The polymer composition as claimed in claim 1, wherein the density of the polymer composition is from 950 to 965 kg/m.sup.3.

10. The polymer composition as claimed in claim 1, wherein the MFR.sub.2 of the polymer composition is from 0.4 to 6.0 g/10 min.

11. The polymer composition as claimed in claim 1, wherein the polymer composition further comprises from 0.2 to 9.0 wt % of a carbon black product.

12. The polymer composition as claimed in claim 1, wherein the polymer composition comprises: from 10 to 70 wt % of the first high density polyethylene; from 30 to 90 wt % of the second high density polyethylene; from 0 to 5 wt % additives; and from 0 to 9 wt % of a carbon black product.

13. The polymer composition as claimed in claim 1, wherein the MFR.sub.2 according to ISO 1133 of the second high density polyethylene (HDPE) is from 2.0 to 8.0 g/10 min.

14. An article comprising the polymer composition as claimed in claim 1.

15. The article as claimed in claim 14, wherein said article is a pallet.

16. A pallet consisting of the polymer composition as claimed in claim 1.

17. A process for the preparation of an article as claimed in claim 14, the process comprising blending the first high density polyethylene and the second high density polyethylene to form the polymer composition and moulding the polymer composition to prepare said article.

18. A method of use of the polymer composition as claimed in claim 1, the method comprising using the polymer composition in the manufacture of an article.

19. The method of use according to claim 18, wherein said article is a pallet.

20. A pallet comprising a polymer composition, the polymer composition comprising: a blend of two or more high density polyethylenes comprising: a first high density polyethylene having a density of at least 940 kg/m.sup.3 and an MFR.sub.2 of 0.25 g/10 min or less; and a second high density polyethylene having a density of at least 940 kg/m.sup.3 and an MFR.sub.2 of from 1.0 g/10 min to 20 g/10 min, and wherein the second high density polyethylene is multimodal and comprises from 30 to 70 wt % of a lower Mw component and from 70 to 30 wt % of a higher Mw component; wherein said polymer composition has an MFR.sub.2 of from 0.25 to 15 g/10 min, and wherein the first high density polyethylene and the second high density polyethylene combined form at least 91 wt % of said polymer composition.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The FIGURE demonstrates the Edge Test as described below.

ANALYTICAL TESTS

(2) Melt Flow Rate

(3) The melt flow rate (MFR) is determined according to ASTM D1238 and is indicated in g/10 min. The MFR is an indication of the melt viscosity of the polymer. The MFR is determined at 190° C. for polyethylene. The load under which the melt flow rate is determined is usually indicated as a subscript, for instance MFR.sub.2 is measured under 2.16 kg load, MFR.sub.5 is measured under 5 kg load or MFR.sub.21 is measured under 21.6 kg load.

(4) Density

(5) Density of the polymer was measured according to ISO 1183-1:2004 Method A on compression moulded specimen prepared according to EN ISO 1872-2 (February 2007) and is given in kg/m.sup.3.

(6) Molecular Weight

(7) M.sub.w, M.sub.n and MWD are measured by Gel Permeation Chromatography (GPC) according to the following method:

(8) The weight average molecular weight M.sub.w and the molecular weight distribution (MWD=M.sub.w/M.sub.n, wherein M.sub.n is the number average molecular weight and M.sub.w is the weight average molecular weight) is measured according to ISO 16014-4:2003 and ASTM D 6474-99. A Waters GPCV2000 instrument, equipped with refractive index detector and online viscosimeter was used with 2×GMHXL-HT and 1×G7000HXL-HT TSK-gel columns from Tosoh Bioscience and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg/L 2,6-Di tert-butyl-4-methyl-phenol) as solvent at 140° C. and at a constant flow rate of 1 mL/min. 209.5 μL of sample solution were injected per analysis. The column set was calibrated using universal calibration (according to ISO 16014-2:2003) with at least 15 narrow MWD polystyrene (PS) standards in the range of 1 kg/mol to 12 000 kg/mol. Mark Houwink constants were used as given in ASTM D 6474-99. All samples were prepared by dissolving 0.5-4.0 mg of polymer in 4 mL (at 140° C.) of stabilized TCB (same as mobile phase) and keeping for max. 3 hours at a maximum temperature of 160° C. with continuous gentle shaking prior sampling in into the GPC instrument.

(9) As it is known in the art, the weight average molecular weight of a polymer composition can be calculated if the molecular weights of its components are known according to:

(10) ${\mathrm{Mw}}_b=\underset{i}{.Math.}{w}_i.Math.{\mathrm{Mw}}_i$

(11) where Mw.sub.b is the weight average molecular weight of the polymer composition, w.sub.i is the weight fraction of component “i” in the polymer composition and Mw.sub.i is the weight average molecular weight of the component “i”.

(12) The number average molecular weight can be calculated using the well-known mixing rule:

(13) $\frac{1}{{\mathrm{Mn}}_b}=\underset{i}{.Math.}\frac{w_i}{{\mathrm{Mn}}_i}$

(14) where Mn.sub.b is the number average molecular weight of the polymer composition, w.sub.i is the weight fraction of component “i” in the polymer composition and Mn.sub.i is the number average molecular weight of the component “i”.

(15) Notched Charpy Impact Strength

(16) Charpy notched impact strength was determined according to ISO 179-1:2000 on notched specimens of 80×10×4 mm at a testing temperature of 23±2° C. Injection moulding of the impact specimens was carried out according to ISO 1873-2:2007.

(17) Edge Test: A test similar to corner drop test of EN ISO 8611 (1-3) (2012) standard is carried out in which the pallet is dropped once onto its edge (the longer edge if there is one) from a height of 3 m. Cracking is checked visually. Crack testing is carried out at room temperature. The FIGURE demonstrates the procedure.

(18) Materials

(19) The following commercial materials produced (supplied by Borouge) are used in the examples:

(20) TABLE-US-00001 TABLE 1 MFR2 MFR5 190° C./ 190° C./ Density 2.16 kg 2.16 kg Materials Comment [kg/m3] [g/10 min] [g/10 min] HE3460* Multimodal high density 960 <0.1 0.4 polyethylene polymer MB7581 Multimodal high density 958 4.0 14.0 polyethylene polymer Component homopolymer of na 9.1 Na C2 propylene (230 C.) Component Multimodal high density 956 0.9 3.3 C3 polyethylene polymer Component Linear low density 923 0.3 0.9 C4 polyethylene Component Heterophasic copolymer na 7.0 na C5 of propylene (230 C.) *contains carbon black more than 2 wt % and up to 4 wt %

(21) Both the commercial grades HE3460 and MB7581 are supplied by Borouge and produced by conventional polymerisation methods using a conventional catalyst. The components C2-C5 are commercial and/or produced by conventional polymerisation methods using a conventional catalyst.

(22) Inventive compositions IE1-IE3 and comparative compositions (CE1-CE10) were compounded in a commercial mixer using conventional compounding conditions. The compositions were comparable for each inv. and comparative composition. The polymer components and amounts thereof are disclosed in table 2. The compositions comprised comparable conventional additives in comparable amounts.

(23) TABLE-US-00002 TABLE 2 MFR2 Charpy Test 190° C./2.16 kg [J/m2] Nr. Blend materials [g/10 min] Spec: >8000  1  80% MB7581 2.5 10,839 (IE1)  20% HE3460  2  60% MB7581 1.2 13,577 (IE2)  40% HE3460  3  40% MB7581 0.5 14,166 (IE3)  60% HE3460 MFR2 230° C./2.16 kg (or 190° C./2.16 kg Nr. Blend materials [g/10 min]  4  55% MB7581 2.7 (190° C.) (CE1)  25% HE3460  20% C2  5  63% MB7581 1.8 (190° C.) (CE2)  27% HE3460  10% C2  6  55% C3 0.7 (190° C.) (CE3)  25% HE3460  20% C2  7 100% C3 1.0 (190° C.) (CE4)  8  90% C2 6.5 (CE5)  10% HE3460  9  80% C2 6.3 (CE6)  20% HE3460 10  90% C2 1.8 (CE7)  10% C4 11  80% C2 2.7 (CE8)  20% C4 12  90% C2 10.7 (CE9)  10% C5 13  70% C2 10.9 (CE10)  30% C5

(24) Polymer compositions of the invention/comparative examples are injection moulded into PP7 type pallets.

(25) Pallet Dimensions and Tolerances, mm

(26) Length 1300 (±5) Width 1100 (±5) Height 150 (±2)

(27) Weight, Kg 12-18 kg, Double Deck

(28) The formed pallets are tested and results presented in table 3.

(29) TABLE-US-00003 TABLE 3 1 × 3 m 1 × 3 m Edge Edge Drop Drop [1 drop] Blending Spec: no Blending Spec: no Nr. materials crack Nr. materials crack 1  80% MB7581 no  8 90% C2 crack (IE1)  20% HE3460 crack (CE5)  10% HE3460 2  60% MB7581 no  9 80% C2 crack (IE2)  40% HE3460 crack (CE6)  20% HE3460 3  40% MB7581 no 10 90% C2 crack (IE3)  60% HE3460 crack (CE7)  10% C4 4  55% MB7581 crack 11 80% C2 crack (CE1)  25% HE3460 (CE8)  20% C4  20% C2 5  63% MB7581 crack 12 90% C2 crack (CE2)  27% HE3460 (CE9)  10% C5  10% C2 6  55% C3 crack 13 70% C2 crack (CE3)  25% HE3460 (CE10) 30% C5  20% C2 7 100% C3 crack (CE4)