SOLID CATALYST FOR THE PREPARATION OF NUCLEATED POLYOLEFINS

Abstract

The present invention is directed to solid catalyst particles comprising a Ziegler-Natta catalyst and a polymeric nucleating agent. Further, the present invention is also directed to a process for the preparation of said solid catalyst particles, the use of said solid catalyst particles in a process for the manufacture of a polymer and a polyolefin obtained in the presence of said solid catalyst particles.

Claims

1: Solid catalyst particles, comprising: (a) a Ziegler-Natta 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); (b) a co-catalyst (Co), (c) optionally an external donor (ED), and (d) a polymeric nucleating agent obtained from a vinyl monomer of formula (I):
CH.sub.2CHCHR.sup.1R.sup.2(I), wherein R.sup.1 and R.sup.2, together with the carbon atom they are attached to, form an optionally substituted saturated or unsaturated or aromatic ring or a fused ring system, wherein the ring or fused ring moiety contains four to 20 carbon atoms, wherein said solid catalyst particles are not dissolved or suspended in a liquid medium.

2: Solid catalyst particles according to claim 1, wherein the polymeric nucleating agent is selected from the group of polyvinylalkanes or polyvinylcycloalkanes.

3: Solid catalyst particles according to claim 1, wherein the compounds (TC) of a transition metal of Group 4 to 6 of IUPAC are selected from the group consisting of Group 4 and Group 5 compounds.

4: Solid catalyst particles according to claim 1, wherein the Group 2 metal compound (MC) is a magnesium compound.

5: Solid catalyst particles according to claim 1, wherein the polymeric nucleating agent comprising vinyl monomer units is obtained in the presence of the Ziegler-Natta 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), a co-catalyst (Co), and optionally an external donor (ED).

6: Solid catalyst particles according to claim 1, wherein the co-catalyst (Co) is selected from the group consisting of organometallic compounds of Group 13 metal selected from trialkylaluminium, dialkyl aluminium chloride, alkyl aluminium dichloride and mixtures thereof, where the alkyl is a C1-C4 alkyl.

7: Solid catalyst particles according to claim 1, wherein the internal donor (ID) is selected from 1,3-diethers and (di)esters of (di)carboxylic acids of formula (II): ##STR00003## wherein R.sup.1 and R.sup.2 are independently a C.sub.2-C.sub.18 alkyl, preferably C.sub.2-C.sub.8 alkyl.

8: Solid catalyst particles according to claim 1, wherein the external donor (ED) is selected from silanes of: a compound of formula (III):
R.sup.3.sub.nR.sup.4.sub.mSi(OR.sup.5).sub.4-n-m(III), wherein R.sup.3, R.sup.4 and R.sup.5 can be the same or different and represent linear, branched or cyclic aliphatic or aromatic groups, and n and m are 0, 1, 2 or 3 and the sum n+m is equal to or less than 3, or a compound of formula (IV):
Si(OCH.sub.2CH.sub.3).sub.3(NR.sup.3R.sup.4)(IV), wherein R.sup.3 and R.sup.4 can be the same or different and represent a linear, branched or cyclic hydrocarbon group having 1 to 12 carbon atoms, or is a compound of formula (V):
R.sup.6R.sup.7C(COMe).sub.2(V), wherein R.sup.6 and R.sup.7 can be the same or different and stand for a branched aliphatic or cyclic or aromatic group.

9: Process for the preparation of solid catalyst particles according to claim 1, comprising the steps of: i) polymerizing a vinyl monomer of formula (I):
CH.sub.2CHCHR.sup.1R.sup.2(I) wherein R.sup.1 and R.sup.2 are defined as is claim 1, at a weight ratio of the vinyl monomer to the catalyst amounting to 0.1 to below 5, in the presence of; (a) a Ziegler-Natta 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); (b) a co-catalyst (Co), (c) optionally an external donor (ED), and (d) an organic inert solvent (S) having a boiling point below 130 C. which does not essentially dissolve the polymerized vinyl compound, ii) continuing the polymerization reaction of the vinyl monomer until the concentration of unreacted vinyl monomer is less than 1.5 wt. %, iii) removing the solvent (S) to obtain the catalyst in the form of dry solid particles.

10: Process according to claim 9, wherein the solvent (S) is selected from unbranched or branched C.sub.4 to C.sub.8 alkanes.

11. (canceled)

12: Polyolefin prepared in the presence of the solid catalyst particles according to claim 1.

13: Polyolefin according to claim 12, wherein the polyolefin is a propylene homopolymer having: i) a flexural modulus measured according to ISO 178 above 2100 MPa and/or ii) a crystallization temperature Tc above 129 C.

Description

EXAMPLES

1. Definitions/Measuring Methods

[0156] The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

[0157] MFR.sub.2 (230 C.) is measured according to ISO 1133 (230 C., 2.16 kg load).

[0158] Xylene cold soluble fraction (XCS wt.-%): Content of xylene cold solubles (XCS) is determined at 25 C. according ISO 16152; first edition; 2005 Jul. 1.

[0159] DSC analysis, melting temperature (T.sub.m), crystallization temperature (T.sub.e) and heat of crystallization (H.sub.c): measured with a TA Instrument Q200 differential scanning calorimetry (DSC) on 5 to 7 mg samples. DSC is run according to ISO 11357/part 3/method C2 in a heat/cool/heat cycle with a scan rate of 10 C./min in the temperature range of 30 to +225 C. Crystallization temperature (T.sub.c) and crystallization enthalpy (H.sub.c) are determined from the cooling step, while melting temperature (T.sub.m) are determined from the second heating step. The crystallinity is calculated from the melting enthalpy by assuming an Hm-value of 209 J/g for a fully crystalline polypropylene (see Brandrup, J., Immergut, E. H., Eds. Polymer Handbook, 3rd ed. Wiley, New York, 1989; Chapter 3).

[0160] Flexural Modulus:

[0161] The polymer powder was stabilised with 1500 ppm Irganox B215 and 500 ppm Ca stearate prior to melt homogenisation on a Prism extruder. The pellets were injection moulded into 60602 mm plates with an Engel Es 80/25HL The test bars (10502 mm) were punched out from the plates in flow direction. The flexural modulus of the test bars was determined in a 3-point-bending according to ISO178.

[0162] FTIR isotacticity: FTIR spectrum is obtained from a pressed PP film which is tempered in a vacuum oven for

[0163] 1 hour and rested at room temperature for 16-20 h.

[0164] I.I. is an indirect method for determination of isotacticity in polypropylene based on works ofD. Burfield and P. Loi (J. Appl. Polym. Sci. 1988, 36, 279) and CHISSO Corp. (EP277514B1; 1988). It is the ratio of isotactic absorption band at 998 cm-1 to reference band at 973 cm-1. It can be expressed by the equation:

I.I.=A998/A973

[0165] A998 corresponds to 11-12 repeat units in crystalline regions

[0166] A973 corresponds to 5 units in amorphous and crystalline chains

[0167] I.I. is not direct comparable to isotacticity by NMR.

2. Examples

Reference Example: Preparation of the Ziegler-Natta Catalyst (ZN PP)

[0168] First, 0.1 mol of MgCl.sub.23 EtOH was suspended under inert conditions in 250 ml of decane in a reactor at atmospheric pressure. The solution was cooled to the temperature of 15 C. and 300 ml of cold TiCl.sub.4 was added while maintaining the temperature at said level. Then, the temperature of the slurry was increased slowly to 20 C. At this temperature, 0.02 mol of dioctylphthalate (DOP) was added to the slurry. After the addition of the phthalate, the temperature was raised to 135 C. during 90 minutes and the slurry was allowed to stand for 60 minutes. Then, another 300 ml of TiCl.sub.4 was added and the temperature was kept at 135 C. for 120 minutes. After this, the catalyst was filtered from the liquid and washed six times with 300 ml heptane at 80 C. Then, the solid catalyst component was filtered and dried.

[0169] Catalyst and its preparation concept is described in general e.g. in patent publications EP491566, EP591224 and EP586390.

Example 1

1a) Vinylcyclohexane Modification of the ZN PP Catalyst in Pentane

[0170] 300 ml of pentane, 4.15 ml of triethyl aluminium (TEAL) and 1.85 ml dicyclopentyl dimethoxy silane (Do) (CAS number 126990-35-0) were added to a 1 liter reactor. After 20 minutes 20 g of the ZN PP catalyst prepared according to the reference example with Ti content 1.9 wt % was added. The Al/Ti and Al/Do molar ratios were 3.8. 20 g of vinylcyclohexane (VCH, CAS Number 695-12-5) was added during 1 hour at room temperature. The temperature was increased to 50 C. during 50 minutes and was maintained there for 2.3 hours followed by cooling to room temperature.

[0171] A small sample (5-10 ml) was withdrawn from the reactor and mixed with 50 gl of isopropanol to stop the reaction. The amount of unreacted VCH in the sample was analysed with gas chromatography (GC) and was found to be 0.42 wt %, which corresponds to a 95.5% conversion of VCH.

[0172] The major part of pentane in the pentane/catalyst/TEAL/donor/polyVCH mixture was removed by decanting. The remaining pentane in the mixture was removed by flushing with nitrogen

[0173] 1b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0174] Polymerization with the VCH modified catalyst was done in a 5 liter reactor. 0.158 ml TEAL, 0.027 ml donor Do and 30 ml pentane were mixed and allowed to react for 5 minutes. Half of the mixture was added to the reactor and the other half was mixed with 23.4 mg of dried VCH modified catalyst (=11.7 mg of pure catalyst). After 10 minutes the mixture was added to the reactor. The Al/Ti molar ratio was 250 and Al/Do molar ratio 10. 550 mmol hydrogen and 1400 gram propylene were added into the reactor and the temperature was raised to 80 C. within 20 minutes while mixing. The reaction was stopped after 1 hour at 80 C. by flashing out unreacted propylene. Polymerization activity was 53 kgPP/gcath. The polymer powder was stabilized with 500 ppm Ca stearate and 1500 ppm Irganox B215 prior to palletisation on a Prism extruder. The pellets were injection moulded into plates on Engel ES 80/25HL. Flexural modulus was measured on test bars cut from the injection moulded plates. The stiffness was 2170 MPa and the other polymer structure properties are shown in table 1.

Example 2

2a) VCH Modification of the ZN PP Catalyst in Pentane

[0175] The VCH modification step in this example was done in accordance with example 1a, except that the reaction temperature was 40 C. and reaction time 2.8 hours. The amount of unreacted VCH was 0.38 wt % in the mixture, which corresponds to a 95.9% conversion of VCH.

2b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0176] Polymerization was done in accordance with example 1b, except that slightly higher amount of catalyst was used, 13.0 mg. Polymerization activity was 55 kgPP/gcath and stiffness 2190 MPa. The other polymer structure properties are shown in table 1.

Example 3

3a) VCH Modification of the ZN PP Catalyst in Pentane

[0177] The VCH modification step in this example was done in accordance with example 1a, except that the reaction time was 6 hours. The amount of unreacted VCH was 0.26 wt % in the mixture, which corresponds to a 97.2% conversion of VCH.

3b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0178] Polymerization was done in accordance with example 1b, except that slightly higher amount of catalyst was used, 13.2 mg. Polymerization activity was 54 kgPP/gcath and stiffness 2210 MPa. The other polymer structure properties are shown in table 1.

Example 4

4a) VCH Modification of the ZN PP Catalyst in Pentane

[0179] This example was done in accordance with example 1a, except that the reaction time at 50 C. was 6 hours and that higher amount of catalyst was used, 30 g, and pentane, 325 ml, giving a mixture with higher catalyst concentration. The amount of unreacted VCH was 0.045 wt % in the mixture, which corresponds to a 99.6% conversion of VCH.

4b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0180] Polymerization was done in accordance with example 1b, except that slightly higher amount of catalyst was used, 13.2 mg. Polymerization activity was 62 kgPP/gcath and stiffness 2210 MPa. The other polymer structure properties are shown in table 1.

Comparative Example 1 (CE1)

C1a) VCH Modification of the ZN PP Catalyst in Oil

[0181] This comparative example was done in accordance with example 1a, except that oil (Shell Ondina oil 68) was used as medium 114 ml, catalyst amount was 40 g, Ti content in catalyst was 2.1 wt %, Al/Ti and Al/Do molar ratio 3.0, VCH/catalyst weight ratio 0.8, reaction temperature 55 C. and reaction time 20 hours. After the reaction 38 ml of a wax, White Protopet 1SH from Witco, was added to the mixture as a viscosity modifying agent. The amount of unreacted VCH was 0.085 wt % in the mixture, which corresponds to a 99.4% conversion of VCH.

C1b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0182] This comparative example was done in accordance with example 1b, except that the catalyst amount was 10.3 mg. The polymerization activity was 66 kgPP/gcath and stiffness 2080 MPa. The other polymer structure properties are shown in table 1.

Comparative Example 2 (CE2)

C2a) VCH Modification of the ZN PP Catalyst in Oil

[0183] This comparative example was done in accordance with comparative example C1a, except that the catalyst amount was 18 g, VCH/catalyst weight ratio was 2.0 and the Al/Ti and Al/Do molar ratio 4.5. The amount of unreacted VCH in the mixture was 0.15 wt %, which corresponds to a 99.2% conversion of VCH.

C2b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0184] This comparative example was done in accordance with example 1b, except that the catalyst amount was 8.9 mg. The polymerization activity was 89 kgPP/gcath and stiffness 2030 MPa. The other polymer structure properties are shown in table 1.

Comparative Example 3 (CE3)

C3a) VCH Modification of the ZN PP Catalyst in Oil

[0185] This comparative example was done in accordance with comparative example C1a, except that the catalyst amount was 18 g, Al/Ti and Al/Do molar ratio 4.5 and reaction temperature 65 C. The amount of unreacted VCH in the mixture was 0.034 wt %, which corresponds to a 99.6% conversion of VCH.

C3b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0186] This comparative example was done in accordance with example 1b, except that the catalyst amount was 9.0 mg. The polymerization activity was 66 kgPP/gcath and stiffness 2000 MPa. The other polymer structure properties are shown in table 1.

Comparative Example 4 (CE4)

C4a) VCH Modification of the ZN PP Catalyst in Oil

[0187] This comparative example was done in accordance with comparative example C1a, except that the catalyst amount was 18 g, Al/Ti and Al/Do molar ratio 4.5, VCH/catalyst weight ratio 2.0 and reaction temperature 65 C. The amount of unreacted VCH in the mixture was 0.022 wt %, which corresponds to a 99.9% conversion of VCH.

C4b) Use of the VCH Modified ZN PP Catalyst in Propylene Polymerization

[0188] This comparative example was done in accordance with example 1b, except that the catalyst amount was 9.2 mg. The polymerization activity was 82 kgPP/gcath and stiffness 2090 MPa. The other polymer structure properties are shown in table 1.

[0189] Crystallisation temperature is a good indicator of how efficient the nucleator is. Higher Tcr means more effective nucleation and higher stiffness in the end product. FTIR isotacticity is also closely linked to the stiffness of the final product. Higher isotacticity means higher stiffness. From table 1 it can be seen that the if VCH modification is done in pentane it increases Tcr with in average 0.8 C. and isotacticity with in average 1%. The effect of this increase in Tcr and isotacticity is seen as an increase in stiffness with in average 150 MPa. From table 1 it can be seen that even if increasing the amount of polyVCH in the final product with the preparation in oil recipe (=comparative examples) to higher values than in the preparation in pentane (=examples) still the stiffness is clearly lower in the comparative examples.

TABLE-US-00001 TABLE 1 Polymerization conditions and properties of the obtained polypropylene Ex 1 Ex 2 Ex 3 Ex 4 CE1 CE2 CE3 CE4 VCH modification Catalyst [g] 20 20 20 30 40 18 18 18 Medium pentane pentane pentane pentane oil oil oil oil Medium amount [ml] 300 300 300 325 114 114 114 114 VCH/cat (wt/wt) [] 1.0 1.0 1.0 1.0 0.8 2.0 0.8 2.0 Temperature [ C.] 50 40 50 50 55 55 65 65 Time [h] 2.3 2.8 6.0 6.0 20 20 20 20 VCH conversion [%] 95.5 95.9 97.2 99.6 99.4 99.2 99.6 99.9 Propylene polymerization Catalyst (pure) [mg] 11.7 13.0 13.2 13.2 10.3 8.9 9.0 9.2 Yield [g] 623 716 711 820 676 793 595 756 Actvity [kgPP/gcath] 53 55 54 62 66 89 66 82 PolyVCH in [ppm] 18 18 19 16 12 22 12 24 polymer* Polymer properties MFR [g/10 min] 14.3 14 13.7 13 15.9 18.6 16.6 18.1 XS [wt.-%] 1.1 1.1 1.1 1.0 1.1 1.2 1.3 1.1 FTIR isotacticity [%] 104.0 103.9 103.0 103.0 102.7 102.6 102.1 102.5 Tm [ C.] 166.8 166.8 166.8 166.5 166.2 166.0 166.0 166.2 Tcr [ C.] 129.4 129.2 129.3 129.2 128.2 128.7 128.3 128.7 Flexural modulus [MPa] 2170 2190 2210 2210 2080 2030 2000 2090 *calculated amount based on the amount polyVCH in the catalyst and activity of the propylene polymerization