1-Butene Polymerization with Ethylenebis-(1-indenyl)zirconium

Chapter 5

1-Butene Polymerization with Ethylenebis(1-indenyl)zirconium Dichloride and Methylaluminoxane Catalyst System

Downloaded by STANFORD UNIV GREEN LIBR on October 11, 2012 | http://pubs.acs.org Publication Date: June 22, 1992 | doi: 10.1021/bk-1992-0496.ch005

Effect of Hydrogen Addition M. Kioka, A. Mizuno, T. Tsutsui, and N. Kashiwa Mitsui Petrochemical Industries, 3 - 2 - 5 Kasumigaseki Chiyoda-ku, Tokyo, Japan Butene-1 polymerizations were performed with and without hydrogen addition using ethylenebis(1-indenyl)zirconium dichloride and methylaluminoxane catalyst system. The catalyst activity was remarkably enhanced by 60-70 times by addition of hydrogen. The obtained polymers were characterized by C NMR, DSC and intrinsic viscosity measurements. The reason for the activity enhancement by hydrogen addition is discussed on the basis of the analytical data. 13

Isotactic propylene polymerization with ethylenebis(l-indenyl) zirconium dichloride (Et(Ind) ZrCl ) or ethylenebis(4,5,6,7-tetrahydro1-indenyl)zirconium dichloride (Et(TH-Ind) ZrCl2) in conjunction with methylaluminoxane (MAO) has been reported in the literature (1-3). The structural features (4-7 and Mizuno,A. et.al. Polymer,in press) of the polymers are high isotacticity and the presence of a small amount of irregular units based on 2,1- or 1,3-propylene insertion. The effect of hydrogen on propylene polymerization catalyzed by Et(Ind) ZrCl with MAO has been also reported (8). Namely, with the addition of hydrogen, the activity was enhanced three times. As one of the most plausible reasons for the activity enhancement, the chain transfer reaction with hydrogen at 2,1-inserted active chain ends was proposed In this paper, butene-1 polymerizations with Et(Ind) ZrCl and MAO catalyst system were performed with hydrogen addition (H system) and without (non-Eb system) in order to get further information concerning the hydrogen effect. On the basis of detailed information on the polymer microstructures, the effect of hydrogen on the activity was also discussed. 2

2

2

2

2

2

2

2

0097-6156/92/0496-0072$06.00/0 © 1992 American Chemical Society

In Catalysis in Polymer Synthesis; Vandenberg, E., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1992.

5. KIOKA ET AL.

73

1-Butène Polymerization

Experimental Preparation of catalyst. Et(Ind) ZrCl according to previous papers. 2

2

(6) and MAO (9) were prepared

Polymerization of butene-1. In a 500ml glass reactor equipped with a stirrer, 250ml of toluene were placed and pure butene-1 or a mixture of butene-1 and hydrogen was bubbled through the system. Subsequently, 0.15g of MAO (=ca.2.5mmol of Al) and 2.5 x 10~ mmol of Et(Ind) ZrCl were added at 3 0 Ό , in this order. Polymerization was carried out under atmospheric pressure at 30Ό for 1 hr and stopped by the addition of a small amount of methanol. The whole product was poured into a large amount of methanol. The resulting powdery polymer was collected by filtration and dried in vacuum at 80°C for 12hr.


3

2

2

Intrinsic viscosity measurement. Intrinsic viscosity was measured at 135Ό using decalin as solvent. DSC measurement. DSC curves were recorded at a heating rate of 10°C min in order to measure melting temperature on a Perkin-Elmer 7 differential scanning calorimeter. The instrument was calibrated by the measurements of the melting points of indium and lead. The weight of the sample was — 5mg. -1

C NMR measurement. The polymer solution was prepared by dissolving ~ 100 mg of the polymer sample at 120 Ό in ca. 0.6ml of hexachlorobutadiene, including ca. 0.05ml of deuterobenzene which was used for field stabilization, in a 5 mm o.d. glass tube. C{1H} NMR spectra were recorded on a JEOL GX-500 spectrometer operating at 125.8MHz in a Fourier-transform mode. Instrumental conditions were as follows: pulse angle 45° ; pulse repetition time 5.0s; spectral width 20000 Hz; number of scans 20000 - 30000; data point 64k. The H decoupled DEPT method was also used to discriminate the carbon species. The C{1H} NMR spectra of the polymers dissolved in perdeuterocyclohexane at 60*0 were also measured in order to observe olefinic carbon resonances, which may be hidden under the solvent resonances in hexachlorobutadiene solution. 13

13

!

13

Results and discussion In Table 1 are shown the results of butene-1 polymerizations with Et(Ind) ZrCl and MAO catalyst system. In the H system, the catalyst activity per unit butene-1 pressure was almost constant, not depending on the concentration of H under these experimental conditions, but remarkably enhanced by 60-70 times in comparison with in the non-H2 system. This activity enhancement was much higher than that of propylene polymerization in our previous paper (8). 2

2

2

2


74

CATALYSIS IN POLYMER SYNTHESIS

The molecular weight in terms of intrinsic viscosity of the polymerdecreased by the addition of 10% of hydrogen to butene-1, but further addition resulted in practically no change of the molecular weight.


Table 1.

Effect of hydrogen on butene-1 (C^) polymerization

Run C^-Flow Hs-Flow Yield Activity No. (gPB-1/ (1/h) (1/h) (&) mmol·Zr·h) 1 2 3 4

50 50 50 50

0 5 10 20

1.2 76.7 82.0 81.4

Intrinsic viscosity (dl/g)

(°C)

93.2 98.4 97.1 97.6

0.28 0.19 0.20 0.18

240 15340 16400 16280

Melting temperature

The microstructures of the polymers obtained both in the non-Hs and H systems were investigated with the method of high-field C NMR spectroscopy. The observed spectra of Run 1 and 2 are shown in Figure 1. The C spectral features of the samples of Run 3 and 4 were almost same as that of Run 2. The peaks were assigned on the basis of DEPT measurement for determination of carbon species, the chemical shift additive rule of Lindeman-Adams (10) and the previously reported literature data (11). The assignment of the carbon peaks based on the terminal groups and the irregular units is added to Figure 1. The structural features of the polymer obtained in the non-H system was characterized with terminal groups having η-butyl group as the α end group and 2- and 3-pentenyl groups as the ω one, and also with 0.3 and 0.2 units of irregular structures formed by 2,1- and 1,4-insertions of butene-1 per one polymer chain. Moreover, it is noticeable that vinylidene group as ω end group was not detected unlike polypropylene with the same catalyst system. Thus, the above α and ω end groups of the polymer are considered to be formed by the chain transfer reaction in Scheme-1. 1 3

2

1 3

2

Scheme-1 C I

C

I

C

C CA

Ç

Zr-C-C-C-C-P CA

-

? C

I

Ç

C I

Ç

Zr-C-C-C-C + C-C=C-C-C-C-P + C-C-C=C-C-C-P C C Zr-C-O-C-C-C-C

9 CA

c

Zr-C-C-P -* Zr-C-C-C-C + C=C-P (negligible) C^îbutene-l, P;polymer chain


5. KIOKA ET AL.

1-Butène Polymerization

75


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1-Butene Polymerization with Ethylenebis-(1-indenyl)zirconium

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