COMPOSITION COMPRISING HETEROPHASIC PROPYLENE COPOLYMER

Abstract

The invention relates to a composition comprising (A) a propylene-based polymer, (B) an elastomer of ethylene and α-olefin comonomer having 4 to 10 carbon atoms and (C) an inorganic filler, wherein (A) the propylene-based polymer has a melt flow index of 60 to 150 dg/min measured according to ASTM D1238 (2.16 kg/230° C.) and wherein (B) the elastomer has a density of 0.840 to 0.865 g/cm.sup.3, wherein (B) the elastomer has a melt flow index of 3 to 13 dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 190° C., wherein the amount of (B) the elastomer is 2 to 30 wt % based on the total composition, wherein the amount of (C) the inorganic filler is 0.1 to 30 wt % based on the total composition.

Claims

1. A composition comprising (A) a propylene-based polymer, (B) an elastomer of ethylene and α-olefin comonomer having 4 to 10 carbon atoms and (C) an inorganic filler, wherein (A) the propylene-based polymer has a melt flow index of 60 to 150 dg/min measured according to ASTM D1238 (2.16 kg/230° C.) and wherein (B) the elastomer has a density of 0.840 to 0.865 g/cm.sup.3, wherein (B) the elastomer has a melt flow index of 3 to 13 dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 190° C., wherein the amount of (B) the elastomer is 2 to 30 wt % based on the total composition, wherein the amount of (C) the inorganic filler is 0.1 to 30 wt % based on the total composition, and wherein the elastomer is an ethylene-1-octene copolymer.

2. The composition according to claim 1, wherein the elastomer has a melt flow index of 4 to 10 dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 190° C.

3. The composition according to claim 1, wherein the elastomer has a density of 0.850 to 0.865 g/cm.sup.3.

4. The composition according to claim 1, wherein the propylene-based polymer is a heterophasic propylene copolymer consisting of (a) a propylene-based matrix, wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene copolymer consisting of at least 96 wt % of propylene monomer units and at most 4 wt % of ethylene monomer units and/or an α-olefin monomer units having 4 to 10 carbon atoms, based on the total weight of the propylene-based matrix and wherein the propylene-based matrix is present in an amount of 65 to 95 wt % based on the total heterophasic propylene copolymer and (b) a dispersed ethylene-α-olefin copolymer, wherein the dispersed ethylene-α-olefin copolymer is an ethylene-propylene copolymer, wherein the ethylene-α olefin copolymer is present in an amount of 35 to 5 wt % based on the total heterophasic propylene copolymer.

5. The composition according to claim 4, wherein the propylene-based matrix is a propylene homopolymer.

6. The composition according to claim 4, wherein the ethylene-α olefin copolymer is present in an amount of 30 to 5 wt %, based on the total heterophasic propylene copolymer and/or the amount of ethylene monomer units in the ethylene-α-olefin copolymer is in the range of 40 to 65 wt %, based on the ethylene-α-olefin copolymer.

7. The composition according to claim 4, wherein the propylene-based matrix has a melt flow index of 50 to 300 dg/min, measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C. and/or the dispersed ethylene-α-olefin copolymer has a melt flow index of 0.1 to 3 dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.

8. The composition according to claim 4, wherein [(MFI of the heterophasic propylene copolymer in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)−(WI of the composition in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)/[amount of the elastomer in the composition in wt %] is at most 0.7 (dg/min)/wt %.

9. The composition according to claim 1, wherein the amount of the elastomer is 10 to 30 wt % based on the total composition.

10. The composition according to claim 1, wherein the composition has a melt flow index of at least 20 dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.

11. The composition according to claim 1, wherein the inorganic filler is selected from the group consisting of calcium carbonate, talc, magnesium carbonate, synthetic carbonates, wollastonite, dolomite, gypsum, kaolinite, aluminum hydroxide, aluminosilicates, mica, natural siliconates, silica containing aggregates, zeolites and mixtures thereof.

12. The composition according to claim 1, wherein the inorganic filler has a d50 of 1 to 10 μm.

13. A process for the preparation of the composition according to claim 1, comprising melt mixing (A), (B) and (C).

14. An article comprising the composition of claim 1.

15. The composition of claim 6, wherein the ethylene-α olefin copolymer is present in an amount of 25 to 5 wt %, based on the total heterophasic propylene copolymer and/or the amount of ethylene monomer units in the ethylene-α-olefin copolymer is in the range of 45 to 60 wt %, based on the ethylene-α-olefin copolymer.

16. The composition of claim 7, wherein the propylene-based matrix has a melt flow index of 100 to 200 dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.

17. The composition of claim 1, wherein [(MFI of the heterophasic propylene copolymer in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)−(MFI of the composition in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)/[amount of the elastomer in the composition in wt %] is at most 0.6 (dg/min)/wt %.

18. The composition of claim 1, wherein [(MFI of the heterophasic propylene copolymer in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)−(MFI of the composition in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)/[amount of the elastomer in the composition in wt %] is 0.3 to 0.5 (dg/min)/wt %.

Description

EXPERIMENTS

Propylene-Based Polymer

[0068] Heterophasic propylene copolymer consisting of a matrix of a propylene homopolymer and a dispersed ethylene-propylene copolymer was used. The amount (RC) of the dispersed ethylene-propylene copolymer was 17.50 wt %. The amount (RCC2) of ethylene in the dispersed ethylene-propylene copolymer was 53.30 wt %.

[0069] The MFI was as shown in Table 1, measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.

TABLE-US-00001 TABLE 1 Matrix Dispersed phase MFI ratio of matrix Total (dg/min) (dg/min) to dispersed (dg/min) 160.00 1.75 91.43 72.60

Elastomer

[0070] Elastomers of ethylene and 1-octene as shown in Table 2 were used. The MFI shown below was measured according to ASTM D1238 using a 2.16 kg weight and at a temperature of 190° C.

TABLE-US-00002 TABLE 2 Elastomer MFI @ 190° C. Density (g/cm.sup.3) POE1 0.59 0.8681 POE2 0.91 0.857 POE3 1.02 0.8684 POE4 4.87 0.8685 POE5 27.84 0.8678 POE6 5 0.856 POE7 8 0.861

Inorganic Filler

[0071] Talc having a diameter d50 of 6 μm was used.

[0072] Compositions as shown in Tables 3 and 4 were made by melt-mixing in a twin screw extruder. In Table 3, the amount of the elastomer was 15 wt % and the amount of the talc was 15 wt %, both with respect to the total composition. In Table 4, the amount of the elastomer was 25 wt % and the amount of the talc was 15 wt %, both with respect to the total composition.

[0073] The heterophasic propylene copolymer was pre-mixed with anti-oxidant additives and the elastomer, and then the pre-mixed pellets were dosed to 1.sup.st main hopper of the extruder. Talc was separately dosed to 2.sup.nd main hopper of the extruder. The temperature profile in the twin-extruder was 50-150-210-220-230-230-230-230-230-230-230° C., at a throughput of −25 kg/h at 300 rpm. The pellets were dried under 100° C. for 2 h and then injection molded to prepare the parts for testing by FANUC injection molding machine.

[0074] The MFI of the composition was measured according to ASTM D1238 using a 2.16 kg weight at a temperature of 230° C.

[0075] Izod impact strength was measured according to ASTM D 256 at temperatures shown in Tables 3 and 4.

[0076] Flexural modulus was measured according to ASTM D 790.

[0077] The flexural modulus and the Izod impact strength were measured on samples made by injection molding having the required dimensions for the measurements.

TABLE-US-00003 TABLE 3 Experiments CEx0 CEx1 CEx2 CEx3 CEx4 CEx5 Ex6 Ex7 Elastomer (15 — POE1 POE2 POE3 POE4 POE5 POE6 POE7 wt %) MFI2.16 kg/230° C. 41.9 22.5 26.6 24.2 30.8 37.4 33.2 35.5 Decrease in MFI 0 1.29 1.02 1.18 0.74 0.3 0.58 0.43 of the composition by 1 wt % elastomer Flex modulus 1540 1150 1170 1270 1220 1200 1160 1190 (MPa) Notched Izod 44.8 119 201 102 284 312 330 325 impact @ RT (J/m) Notched Izod 28.6 70.5 83.1 68.2 66 83.6 90 85 impact @ 0° C. (J/m) Notched Izod 25.5 55.2 63.9 59 45 57.8 69 65 impact @ −20° C. (J/m) Notched Izod 23.5 41.5 50.6 47.5 33.2 41.8 58 52 impact @ −40° C. (J/m)

[0078] It can be seen that the addition of the elastomer generally leads to a decrease in the MFI. Compositions of Ex 6 and Ex 7 nevertheless have a high MFI. The effect of the elastomer on the MFI of the final composition is also shown in the Table 3 as “Decrease in MFI of the composition by 1 wt % elastomer”. This was calculated as: [(MFI of the heterophasic propylene copolymer in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)−(MFI of the composition in dg/min measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230° C.)/[amount of the elastomer in the composition in wt %]

[0079] This parameter indicates how much decrease in the MFI is caused by the elastomer. It can be seen that the decrease in MFI caused by POE6 and POE7 is small.

[0080] It can also be seen that the compositions of Ex 6 and Ex 7 have the highest impact strength. Thus, it can be concluded that the compositions of Ex 6 and Ex 7 have a good combination of a high MFI and a high impact strength. Further, the flex modulus is at acceptable levels.

TABLE-US-00004 TABLE 4 Experiments CEx0 CEx8 CEx9 CEx10 CEx11 CEx12 Ex13 Ex14 Elastomer (25 — POE1 POE2 POE3 POE4 POE5 POE6 POE7 wt %) MFI2.16 kg/230° C. 41.9 15.5 19.8 17.8 25.4 35.3 27.8 31.7 Decrease in MFI 0 1.06 0.88 0.96 0.66 0.26 0.56 0.41 of the composition by 1 wt % elastomer Flex modulus 1540 894 859 1030 999 908 880 890 (MPa) Notched Izod 44.8 655 678 626 597 427 640 620 impact @ RT (J/m) Notched Izod 28.6 537 644 507 486 287 610 540 impact @ 0 (J/m) Notched Izod 25.5 116 212 122 113 80.1 180 150 impact @ −20 (J/m) Notched Izod 23.5 69.8 105 113 60.8 61.7 99 80 impact @ −40 (J/m)

[0081] Table 4 shows a similar trend as Table 3. The compositions of Ex 13 and Ex 14 have a good combination of a high MFI and a high impact strength, while the flexural modulus is at an acceptable level. The composition of CEx 9 has a high impact strength, but the MFI of the final composition is low.