POLYPROPYLENE COMPOSITION COMPRISING NUCLEATING AGENT

Abstract

The invention is directed to a polypropylene composition comprising (A) a propylene-based polymer, (B) talc and (C) a functionalized polypropylene grafted with an acid or acid anhydride functional group, wherein components (A) and (C) are different, wherein the amount of the talc in the composition is 0.025-4 wt % of the total composition and the amount of the functionalized polypropylene is 0.005-0.75 wt % of the total composition.

Claims

1. A polypropylene composition comprising (A) a propylene-based polymer, (B) talc and (C) a functionalized polypropylene grafted with an acid or acid anhydride functional group, wherein components (A) and (C) are different, wherein the amount of the talc in the composition is 0.025-4 wt % of the total composition and the amount of the functionalized polypropylene is 0.005-0.75 wt % of the total composition.

2. The composition according to claim 1, wherein the acid or acid anhydride functional group is selected from the group consisting of (meth)acrylic acid and maleic anhydride.

3. The composition according to claim 1, wherein the propylene-based polymer is a propylene homopolymer or a random propylene copolymer.

4. The composition according to claim 1, wherein the amount of the talc in the composition is 0.1-1.0 wt % of the total composition and/or the amount of the functionalized polypropylene is 0.01-0.5 wt % of the total composition.

5. The composition according to claim 1, wherein the total of components (A), (B) and (C) is at least 95 wt %.

6. The composition according to claim 1, wherein at least part of the talc is surface-modified.

7. The composition according to claim 1, wherein the surface-modified talc is surface-modified with a polar substance selected from the group of glycols, silanes, amines and amides.

8. The composition according to claim 1, wherein the composition has a crystallization temperature of at least 120° C. determined with DSC according to ISO 11357-1 to ISO11357-5 using a first heating step at a heating rate of 10 per minute up to 200° C., a dynamic crystallization at a cooling rate of 10° C. per minute down to 25° C. and a second heating step at a heating rate of 10° C. per minute up to 200° C.; and at least one of a flexural modulus of at least 1700 N/mm.sup.2 determined according to ASTM D790-10; a tensile strength of at least 35 N/mm.sup.2 determined according to ISO 37/2 and an elongation at break of at least 12% determined according to ISO 527/1A.

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

10. The process according to claim 9, comprising preparing a masterbatch by melt-mixing a portion of (A) the propylene-based polymer, (B) the talc, (C) the functionalized polypropylene and melt-mixing the masterbatch and remainder of (A) the propylene-based polymer.

11. A method for processing the composition of claim 1, comprising processing the composition in injection moulding, injection blow moulding, injection stretch blow moulding, rotational moulding, compression moulding, extrusion and extrusion compression moulding, extrusion blow moulding, sheet extrusion, film extrusion, cast film extrusion, foam extrusion, thermoforming or thin-walled injection moulding.

12. An article comprising the composition of claim 1.

13. The article according to claim 12, wherein the article is an automotive part.

14. A method for increasing the crystallization temperature of a composition, the method comprising combining talc and a functionalized polypropylene grafted with an acid or acid anhydride functional group with the composition, the composition comprising a propylene-based polymer, wherein the polypropylene-based polymer and the functionalized polypropylene are different.

15. A nucleating agent for a composition comprising a polypropylene-based polymer, wherein the nucleating agent comprises talc and a functionalized polypropylene grafted with an acid or acid anhydride functional group, wherein the polypropylene-based polymer and the functionalized polypropylene are different.

16. The composition according to claim 5, wherein the total of components (A), (B) and (C) is at least 98 wt % of the total composition.

17. The composition according to claim 6, wherein at least 80 wt % of the talc is surface-modified.

Description

EXAMPLES 1-2 AND COMPARATIVE EXPERIMENTS A, B and 3D

[0070] The samples were prepared using a propylene homopolymer, Sabic® PP 579S, having a melt flow index (MFI) of 47 dg/min.

[0071] The propylene homopolymer powder was extruded in a twin screw extruder. In all samples 0.1 wt % of the stabilizer Irganox B225 was added. Talc and functionalized polypropylene were added in various amounts as indicated in Table 1. The amounts of components indicated in Table 1 are based on the total composition. The talc was a surface modified talc (Steamic OOSD). The functionalized polypropylene was propylene homopolymer modified with maleic anhydride (Exxelor PO 1020). These additives were mixed with the propylene homopolymer prior to dosing it to the hopper of the extruder.

[0072] The temperature profile in the extruder was 20-20-40-100-170-230-240-240-240° C., at a throughput of 10 kg/h at 300 rpm.

[0073] The samples from the compounding step were injection moulded into test specimens using an Arburg 60T injection-moulding machine. For mechanical measurements 65*65*3.2 mm thick test plaques (ISO 37/2) and 150*10*4 mm tensile bars (ISO 527/1A) were moulded.

EXAMPLE 4 AND COMPARATIVE EXPERIMENT C and 5E

[0074] The experiments were performed in the same way as examples 1-2 and 3D except that the final composition was obtained by preparing a masterbatch and melt-mixing the masterbatch and the propylene homopolymer. The ratio between the masterbatch and the propylene homopolymer was adjusted to obtain the desired final composition. The masterbatch was produced on a WP3033 extruder containing 47.7 wt % of propylene homopolymer Sabic® PP 579S, 50 wt % of talc, 2 wt % of functionalized polypropylene and 0.3 wt % of Irganox B225.

Testing The mechanical properties of the samples were determined as follows:

[0075] Flow was determined by measuring the melt flow index (MFI), also called melt flow rate or melt index, according to ISO1133 (2.16 kg/230° C.).

[0076] Stiffness was determined by measuring the flexural modulus according to ASTM D790 at 23° C., parallel and perpendicular orientation. Before testing the samples were conditioned for 14 days at 23° C. at 50% relative humidity.

[0077] Tensile strength was determined at 23° C. according to ISO37/2 and to ISO 527/1A (test manual 40), parallel orientation. Before testing the samples were conditioned for 14 days at 23° C. at 50% relative humidity.

[0078] The elongation-at-break was determined according to ISO 527/1A(test manual 40), parallel orientation. Before testing the samples were conditioned for 14 days at 23° C. at 50% relative humidity.

[0079] The crystallization temperature was determined by means of differential scanning calorimetry (DSC). The measurement was carried out in accordance with ISO11357-1 to ISO11357-5 using a first heating step at a heating rate of 10° C. per minute up to 200° C., a dynamic crystallization at a cooling rate of 10° C. per minute down to 70° C. and a second heating step at a heating rate of 10° C. per minute up to 200° C. The melting point is the temperature at which the enthalpy versus temperature curve measured during the second heating step displays a maximum.

[0080] The results of the tests are shown in Table 1.

Results

[0081]

TABLE-US-00001 TABLE 1 Example A B 1 2 3D 4 5E C Talc 0.05 wt % 5.0 wt % 0.05 wt % 0.5 wt % 5.0 wt %  0.5 wt % 5.0 wt %  10 wt % Functionalized — —  0.5 wt % 0.5 wt % 0.5 wt % 0.02 wt % 0.2 wt % 0.4 wt % polypropylene masterbatch no no no no no yes yes yes MFI dg/min 44.7 41.5 38.6 40 38.7 48.6 42.6 41.4 Flexural N/mm.sup.2 1717 2159 1802 1925 2262 1976 2389 2615 modulus 23° C. II Flexural N/mm.sup.2 1721 2113 1820 1967 2279 1990 2404 2607 modulus 23° C. L Tensile N/mm.sup.2 34.4 37 36.5 36.8 37.9 36.4 36.9 37.4 strength ISO 37/2 Elongation at % 15.6 11.1 13 14.3 13.6 14.9 14.1 10.1 break ISO 527/1A Crystallisation ° C. 120.2 126.7 122.6 125.1 128.9 125.6 129.7 130.8 temperature

[0082] The comparisons between comp. ex. A and ex. 1 and between comp. ex. B and comp. ex.

[0083] 3D show that the combination of talc and functionalized PP increases crystallization temperature (Tc).

[0084] The comparison of ex. 2 and ex. 4 shows that the addition of talc and functionalized PP as a masterbatch leads to the same degree of increase of crystallization temperature at a much lower amount. Same trend can be seen by comparison of comp. ex. 3D and ex. 5E.

[0085] The comparison of ex. 2 with comp. ex. 3D shows that Tc and flexural modulus are increased by increasing talc amount.

[0086] The comparison of ex 4 and comp. ex. 5E and C shows that the increase in the amount of talc and functionalized PP leads to increase of Tc and flexural modulus but decrease in elongation at break (EAB). When the amount of the talc and the functionalized polypropylene is very high as in comp. ex. C, the EAB is very low.

[0087] The comparison of comp. A with comp. B shows that the addition of talc increases Tc but heavily decreases EAB. However, a further addition of functionalized PP (comp. ex. 3D) further increases Tc while reducing the decrease in EAB.

[0088] By the addition of functionalized PP to a small amount of talc, Tc can be obtained which is comparable to Tc where a higher amount of of talc is added (ex. 2: 0.5 wt % vs comp. ex. B: 5 wt %). The lower amount of talc reduces the decrease in EAB.

[0089] Hence, a combination of good Tc, EAB and flexural modulus may be obtained by the combination of the specific ranges of functionalized PP and talc as described herein. Within this range, higher amount of talc leads to higher flexural modulus and higher Tc and lower EAB. In order to avoid the decrease in EAB, lower amount of talc is preferred.