Polyolefin composition with improved resistance to ESCR

Abstract

Polyolefin composition comprising high density polyethylene, polyolefin elastomer and polypropylene, wherein the polypropylene is selected from homopolymer PP or impact PP and wherein the amount of high density polyethylene is more than 40% by weight of the total amount of high density polyethylene, polyolefin elastomer and impact or homopolymer polypropylene and wherein the total amount of high density polyethylene, polyolefin elastomer and polypropylene is 100% by weight and wherein the high density polyethylene has a density in the range from 940 to 960 kg/m3.

Claims

1. A polyolefin composition comprising a high density polyethylene, a polyolefin elastomer and a polypropylene, wherein the polypropylene is selected from a polypropylene homopolymer or an impact polypropylene and wherein an amount of the high density polyethylene is more than 40% by weight, wherein a total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight and wherein the high density polyethylene has a density in a range from 940 to 960 kg/m.sup.3, the polyolefin elastomer is an ethylene-octene copolymer, and a melt flow index of the polypropylene is greater than 0.3 g/10 min and less than 10 g/10 min, measured according to ISO 1133 at 230 degrees Celsius and 2.16 kg.

2. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the polypropylene homopolymer or impact polypropylene in an amount of greater than 0.1% by weight to less than or equal to 40% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

3. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the polyolefin elastomer in an amount of greater than 0.1% by weight to less than or equal to 40% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

4. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the high density polyethylene in an amount of greater than 41% by weight to less than 90% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

5. The polyolefin composition according to claim 1, wherein an amount of the high density polyethylene is higher than an amount of the polypropylene based on a wt % of the high density polyethylene and a wt % of polypropylene in the composition.

6. The polyolefin composition according to claim 1, wherein a melt flow index of the high density polyethylene ranges between 0.1 and 30 g/10 min, measured according to ISO 1133 at 190 degrees Celsius and 2.16 kg and/or a density of the high density polyethylene ranges between 940 and 958 kg/m.sup.3, measured according to ISO 1183.

7. The polyolefin composition according to claim 1, wherein a density of the polypropylene ranges between 900 kg/m.sup.3 and 920 kg/m.sup.3, measured according to ISO 1183.

8. The polyolefin composition according to claim 1, wherein a melt flow index of the polyolefin elastomer ranges between 0.5 g/10 mi and 30 g/10 min, measured according to ASTM D1238 at 190 degrees Celsius and 2.16 kg and/or a density of the polyolefin elastomer ranges between 857 kg/m.sup.3 and 880 kg/m.sup.3 measured according to ASTM D1505.

9. The polyolefin composition according to claim 1, wherein an Izod impact performance measured according to ISO180 using testbar 4A at 23° C. is greater than 50 kJ/m.sup.2.

10. The polyolefin composition according to claim 1, wherein an environment stress crack resistance ESCR performance measured according to ASTM D1693 Bent Strip ESCR test (Bell test) (10% Igepal CO-630, 50° C.) in machine direction 50% failure is greater than 500 hours.

11. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the polypropylene homopolymer or impact polypropylene in an amount of from greater than 5% by weight to less than 35% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

12. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the polypropylene homopolymer or impact polypropylene in a range between 15% by weight and 30% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

13. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the polyolefin elastomer in a range between 2% by weight and 25% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

14. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the polyolefin elastomer in a range between 9% by weight and 21% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

15. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the high density polyethylene in a range between 45% by weight and 80% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

16. The polyolefin composition according to claim 1, wherein the polyolefin composition comprises the high density polyethylene in a range between 50% by weight and 80% by weight, wherein the total amount of the high density polyethylene, the polyolefin elastomer and the polypropylene homopolymer or impact polypropylene is 100% by weight.

17. The polyolefin composition according to claim 1, wherein an amount of the polypropylene is higher than an amount of the polyolefin elastomer based on a wt % of polypropylene and a wt % of polyolefin elastomer in the composition.

18. The polyolefin composition according to claim 1, wherein a melt flow index of the polypropylene is greater than 0.3 g/10 min and less than 4 g/10 min, measured according to ISO 1133 at 230 degrees Celsius and 2.16 kg.

19. A blow molded article or an injection molded article comprising the polyolefin composition according to claim 1.

20. Pipe system parts, solar hot water tanks, dangerous goods containers, industrial containers, fuel tanks, caps or closures comprising the polyolefin composition according to claim 1.

Description

EXAMPLES

Materials

(1) The materials mentioned in Table 1 were used.

(2) TABLE-US-00001 TABLE 1 Used Materials. MFI in g/10 min Density in kg/m.sup.3 Polyolefin Grade name Measurement method Measurement method HDPE SABIC, CC253 1.8 953 ISO 1133-1: 2011 ISO 1183-1: 2012 2.16 kg at 190° C. POE SABIC, C1070D 1.0 868 ASTM D1238 ASTM D1505 PP random SABIC, 620P 1.7 905 ISO 1133-1: 2011 ISO 1183-1: 2012 2.16 kg at 230° C. PP impact SABIC, 83MF90 1.8 905 ISO 1133-1: 2011 ISO 1183-1: 2012 2.16 kg at 230° C. PP SABIC, 505P 2.0 905 homoploymer ISO 1133-1: 2011 ISO 1183-1: 2012 2.16 kg at 230° C.

Sample Preparation

(3) All components were added together as a dry blend and directly used for injection molding. The dry blends were injection molded on a Arburg Allrounder machine using a standard mold. Injection molding techniques are well-known in the art.

Measurement Methods

Bell Test

(4) The ESCR was measured according to ASTM D1693 Bent Strip ESCR test (Bell test) (10% Igepal CO-630, 50° C.).

Izod

(5) Impact was measured by Izod according to ISO180 using testbar 4 A at 23° C.

Results

(6) Table 2 and Table 3 give an overview of the prepared samples and their ESCR and Impact performance. The inventive examples of Table 2 comprise impact PP, the inventive examples of Table 3 comprise PP homopolymer. Measurements were performed on the injection molded samples in machine direction.

(7) TABLE-US-00002 TABLE 2 Overview of Comparative and Inventive examples and measurement results. The inventive examples comprise HDPE, impact PP and POE. Bell Impact PP test HDPE POE 83MF90 Izod 50% CC253 C1070D (apart from C4) impact failure Example wt % wt % wt % kJ/m.sup.2 hours comparative C1 100 — — 19.8 16 examples C2 80 20 — 74.3 209 C3 70 — 30 74.4 476 C4 75 10 15 79.6 137 random PP 620P inventive Inv. 1 50 20 30 70.7 >1000 examples lnv. 2 75 10 15 77.4 674

(8) The inventive examples Inv.1 and Inv.2 show in comparison to pure HDPE, example C1, an enormous improvement in impact, measured by Izod, and in ESCR, measured by the Bell test.

(9) Blends of HDPE and POE show a higher impact and ESCR performance in comparison to pure HDPE, which is demonstrated here by C2 in comparison to C1. However, the ESCR of HDPE and POE blends is not as good as in comparison to the inventive examples, which is shown here for C2 comparison to Inv. 1.

(10) This is also the case for blends of HDPE and impact PP, as shown for example C3. The inventive samples have a comparable impact performance, but much better ESCR.

(11) Blends of HDPE, POE and random PP do not lead to such high ESCR performance either. This is shown for example C4 in comparison to Inv. 2.

(12) Best impact and ESCR performance are achieved for the inventive examples Inv.1 and Inv.2

(13) TABLE-US-00003 TABLE 3 Overview of Comparative examples and Inventive examples and measurement results. The inventive examples comprise HDPE, PP homopolymer and POE. Bell test HDPE POE homopolymer PP Izod 50% CC253 C1070D 505P impact failure wt % wt % wt % kJ/m.sup.2 hours comparative C1 100 19.8 16 examples C2 80 20 — 74.3 209 C5 70 30 18.6 42 inventive Inv. 3 50 20 30 82.8 >1000 examples Inv. 4 65 20 15 77.5 >1000 Inv. 5 60 10 30 86.1 >1000

(14) The inventive examples Inv.3, Inv.4 and Inv.5 show in comparison to pure HDPE, example C1, an enormous improvement in impact, measured by Izod, and in ESCR, measured by the Bell test.

(15) Blends of HDPE and POE show a higher impact and ESCR performance in comparison to pure HDPE, which is demonstrated here by C2 in comparison to C1. However, the ESCR of HDPE and POE blends is not as good as in comparison to the inventive examples, which is shown here for C2 comparison to Inv. 3 and Inv.4.

(16) Blends of HDPE and PP homopolymer show the same impact and an only slightly improved ESCR performance in comparison to pure HDPE, which is demonstrated here by C5 in comparison to C1. However, the ESCR of HDPE and PP homopolymer blends is not as good as in comparison to the inventive examples, which is shown here for C5 comparison to Inv. 3.

(17) Best impact and ESCR performance are achieved for the inventive examples Inv.3, Inv.4 and Inv.5.