Low emission propylene homopolymer

1. Process for producing a propylene homopolymer in a sequential polymerization process comprising at least two reactors (R1) and (R2), the propylene homopolymer having:

(a) a melt flow rate MFR 2 (230° C./2.16 kg) measured according to ISO 1133 in the range of 0.1 to 90 g/10 min; and

(b) a pentad isotacticity (mmmm) of more than 90.0% determined by 13 C-NMR, wherein further;

(c) the propylene homopolymer fulfills in equation (I):

VOC≦(MFR×2.27)+32.0

wherein,

VOC is the amount of volatile organic compounds (VOC) [in ppm] measured according to VDA 278:2002 of the propylene homopolymer;

MFR is the melt flow rate MFR 2 (230° C./2.16 kg) measured according to ISO 1133 of the propylene homopolymer; the process comprising:

producing in the first reactor (R1) and subsequently transferring into the second reactor (R2) a first propylene homopolymer fraction (H-PP1); and producing in the second reactor (R2) a second propylene homopolymer fraction (H-PP2) in the presence of the first propylene homopolymer fraction (H-PP1), and

wherein the propylene homopolymer has been polymerized in the presence of:

(a) a Ziegler-Natter catalyst (ZN-C) comprising compounds (TC) of a transition metal of group 4 to 6 of IUPAC, a Group 2 metal compound (MC), and an internal donor (ID), wherein said internal donor (ID) is a non-phthalic compound;

(b) optionally a co-catalyst (Co); and

(c) optionally an external donor (ED).

2. Process according to claim 1 , wherein the propylene homopolymer has an amount of volatile organic compounds (VOC) measured according to VDA 278:2002 of equal or below 215 ppm.

3. Process according to claim 1 , wherein the propylene homopolymer has a melting temperature Tm of equal or more than 160° C.

4. Process according to claim 1 , wherein the propylene homopolymer has a crystallization temperature of equal or more than 114° C.

5. Process according to claim 1 , wherein the propylene homopolymer has a xylene cold soluble content (XCS) determined according ISO 16152 (25° C.) of at least 1.8 wt. %.

6. Process according to claim 1 , wherein the propylene homopolymer has 2,1 erythro regio-defects of equal or below 0.4 mol. % determined by 13 C-NMR spectroscopy.

7. Process according to claim 1 , wherein the propylene homopolymer has a pentad isotacticity (mmmm) of more than 93.0% determined by 13 C-NMR.

8. Process according to claim 1 , wherein the propylene homopolymer fulfils in equation (II):

FOG≦(MFR×4.80)+100.0

wherein,

FOG is the amount of fogging compounds (FOG) [in ppm] measured according to VDA 278:2002 of the propylene homopolymer; and

MFR is the melt flow rate MFR 2 (230° C./2.16 kg) measured according to ISO 1133 of the propylene homopolymer.

9. Process according to claim 1 , wherein the propylene homopolymer has an amount of fogging compounds (FOG) measured according to VDA 278:2002 of not more than 490 ppm.

10. Process according to claim 1 , wherein the propylene homopolymer has a tensile modulus measured at 23° C. according to ISO 527-1 (cross head speed 1 mm/min) of at least 1,500 MPa.

11. Article comprising the propylene homopolymer obtained by the process according to claim 1 .

12. Process according to claim 1 , wherein:

(a) the internal donor (ID) is selected from optionally substituted malonates, maleates, succinates, glutarates, cyclohexene-1,2-dicarboxylates, benzoates and derivatives and/or mixtures thereof; and

(b) the molar-ratio of co-catalyst (Co) to external donor (ED) [Co/ED] is 5 to 45.