Injection molded article based on propylene homopolymer
Injection molded article for healthcare applications based on propylene homopolymer.
1. A process for producing an injection molded article comprising a propylene homopolymer, the process comprising:
polymerizing propylene to obtain the propylene homopolymer, wherein the propylene is polymerized in the presence of:
(a) a Ziegler-Natta catalyst (ZN-C) comprising compounds (TC) of a transition metal of Group 4 to Group 6 of IUPAC, a Group 2 meal compound (MC), and an internal donor (ID), wherein said internal donor (ID) is a non-phthalic compound;
(b) a co-catalyst (Co); and
(c) an external donor (ED);
wherein the ratio of co-catalyst (Co) to external donor (ED) [Co/ED] is 5 to 45; and
wherein the propylene homopolymer has:
(a) a melt flow rate MFR 2 (230° C./2.16 kg) measured according to ISO 1133 in the range of 40 to 120 g/10 min;
(b) a pentad isotacticity (mmmm) of more than 92.5% determined by 13 C-NMR;
(c) a meso sequence length (MSL4) of equal or more than 90.0; MSL4 is calculated by formula (1)
MSL
4
=
2
*
[
mmmm
]
[
mmmr
]
+
4
(
1
)
wherein
“[mmmm]” is % of mmmm pentads
“[mmmr]” is % of mmmr pentads,
determined by 13 C-NMR spectroscopy; and
(d) a molecular weight distribution (MWD) of 7.5 or less; and injection molding the propylene homopolymer.
2. The process according to claim 1 , wherein the propylene homopolymer has a meso sequence length (MSL2) of equal or more than 65.0; MSL2 is calculated by formula (2):
MSL
2
=
2
*
[
mm
]
[
mr
]
+
2
(
2
)
wherein
“mm” are % of mm triads,
“[mr]” are % of mr triads,
determined by 13 C-NMR spectroscopy.
3. The process according to claim 1 , wherein the propylene homopolymer has:
(a) a triad syndiotacticity (rr) of not more than 2.5% as determined by 13 C-NMR spectroscopy; and/or
(b) a pentad isotacticity (mmmm) of more than 92.5 to 97.3% as determined by 13 C-NMR spectroscopy.
4. The 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 determined by 13 C-NMR spectroscopy.
5. The process according to claim 1 , wherein the propylene homopolymer has a xylene cold soluble content (XCS) determined according ISO 16152 (25° C.) of below 4.0 wt. %.
6. The process according to claim 1 , wherein the propylene homopolymer has a melting temperature of at least 158° C.
7. The process according to claim 1 , wherein the propylene homopolymer has a crystallization temperature of equal or below 122° C.
8. The process according to claim 1 , wherein the propylene homopolymer is not-visbroken.
9. The process according to claim 1 , wherein the propylene homopolymer has a flexural modulus measured at 23° C. according to ISO 178 of at least 1,350 MPa.
10. The process according to claim 1 , wherein the propylene homopolymer has a clarity measured according to ASTM D 1003/92 on injection molded specimen of 1 mm thickness of at least 55%.
11. The process according to claim 1 , wherein the injection molded article is for healthcare applications.
12. The process according to claim 1 , wherein the injection molded article is selected from the group consisting of syringes, pipette tips, and PCR equipment.
13. The process according to claim 1 , wherein the injection molded article has in its largest dimension a length of not more than 150 mm.
14. The process according to claim 1 , wherein the injection molded article comprises at least 75 wt. %, based on the total weight of the injection molded article, of the propylene homopolymer.
15. The process according to claim 1 , wherein the propylene homopolymer is does not have the following properties:
melt flow rate (MFR), determined at 230° C. and under a load of 2.16 kg according to ISO 1133, 76 g/10 min;
melting temperature (Tm), 161° C.;
crystallization temperature (Tc), 115° C.;
glass transition temperature (Tg), 2.0° C.;
Xylene cold solubles (XCS), 3.3 wt. %;
mmmm pentad fraction (mmmm), 93.2%;
triad syndiotacticity rr (rr), 2.0%;
meso sequence length MSL2, 76;
meso sequence length MSL4, 92;
Flexural Modulus, 1472 MPa;
Shrinkage in flow (SH in flow), 1.1%;
Shrinkage across flow (SH across flow), 1.3%;
React, 3835; and
Clarity (0.1 mm), 61%.
16. The process according to claim 1 ,
wherein said internal donor (ID) is a non-phthalic acid ester.
17. The process according to claim 16 , wherein:
the internal donor (ID) is selected from optionally substituted malonates, maleates, succinates, glutarates, cyclohexene-1,2-dicarboxylates, benzoates and derivatives and/or mixtures thereof.