Alpha-olefin polymers with syndiotactic structure

Abstract: Syndiotactic polymers of alpha-olefins selected from the group consisting of 1-butene, 4-methyl-1-pentene and 4-­ methyl-1-hexene and a method of preparation thereof by polymerizing said olefins with catalysts obtained from specific Zr or Hf cyclopentadienyl compounds and aluminoxane compounds.

Description: This invention relates to new stereoregular crystalline polymers of alpha-olefins, wherein the recurring units represented by: where R = CH 3 , and n is an integer number higher than 10, preferably higher than 50; and which have syndiotactic structure. Isotactic crystalline polymers may be obtained by polymerizing 1-butene, 4-methyl-1-pentene, 4-methyl-1-hexene in the presence of heterogeneous catalysts of the Ziegler-Natta type including, for example, the reaction product of titanium halides with aluminum organometallic compounds. Partially syndiotactic amorphous 1-butene polymers have been obtained by polymerizing the monomer with the VCl 4 -Al(C 2 H 5 ) 2 Cl catalytic system at -90°C [A. Zambelli et al.: Makromol Chem. 115 ,73 (1968)], or by hydrogenizing the syndiotactic poly-1,2-butadiene obtained by polymerizing 1,3-butadiene with catalysts which are the reaction product of organic compounds of titanium, vanadium, chromium, or molybdenum with aluminum trialkyls [G. Natta et al.: Atti Accad. naz. Lincei, Rend. Cl. Sci. fisiche mat. natur. Sez. VIII 28 ,452 (1960]. These polymers, however, present a number of steric as well as structural irregularities, the latter due to a partial head-to-head and tail-to-tail linking of the vinyl group and to the presence of units linked 1-4 in the syndiotactic poly-1,2-butadiene, which hinder the crystallization of the polymer. Crystalline syndiotactic propylene and 1,3-butadiene polymers have been obtained, in the case of the propylene, with catalysts prepared from VCl 4 and AlEt 2 Cl and, in the case of butadiene, from halogen free organometallic compounds of titanium, vanadium, molybdenum or chromium, and aluminum organometallic compounds. By using the catalysts above-mentioned, however, crystalline syndiotactic polymers of 1-butene, 4-methyl-1-pentene, 4-methyl-1-hexene cannot be obtained. It is also known that propylene polymerizes to syndiotactic polymer with catalysts obtained from isopropylidene-(cyclopentadienyl-1-fluorenyl)-zirconium dichloride and polymethyl-alumoxanes [J.A. Ewen et al. J.A.C.S. 110 , 6255-56 (1988) and EP-A- 185918]. However, the application of said catalysts to polymerization of higher alpha-olefins, such as 1-butene or 4-methyl-1-pentene, is not known. Surprisingly it has been found that by using particular catalytic systems it is possible to prepare stereoregular crystalline polymers of 1-butene, 4-methyl-1-pentene and 4-methyl-1-hexene, where the repeating units represented by diagram (I) above are syndiotactically enchained. The catalyst systems that can be used for the preparation of syndiotactic crystalline polyalpha-olefins of the present invention, include the reaction product of components A and B. A is an organometallic aluminum compound of the formula: or where n in 1) is 0 or an integer from 1 to 40, and in 2) is an integer from 2 to 40; R in both 1) and 2) is an alkyl, aryl, arylalkyl or cycloalkyl radical containing from l to 20 carbon atoms. These aluminum compounds may be used alone or mixed with aluminum trialkyls or aluminium halogen alkyls, where the alkyl groups contain from 1 to 8 carbon atoms; B is an organometallic compound of a transition metal of the formula: RMX 2 where R is an isopropylidene-(cyclopentadienyl-1-fluorenyl) group; M = Zr or Hf; X is halogen, hydrogen, alkyl, aryl, arylalkyl radical containing from 1 to 12 carbon atoms, -OR' (where R' is an alkyl, aryl, arylalkyl group containing from 1 to 12 C atoms), -OH, -CH 2 -Si(CH 3 ) 3 radical, and the X substituents can be the same or different. Figure 1 is the 13 C NMR spectrum of syndiotactic polybutene of the invention. Figure 2 is the X-ray diffraction spectrum of the syndiotactic polybutene of the invention. Figure 3 is the 13 C NMR spectrum of syndiotactic poly-4-methyl-1-pentene of the invention. Figure 4 is the X-ray diffraction spectrum of the syndiotactic poly-4-methyl-1 pentene of the invention. Figure 5 is the thermal stability curve of syndiotactic poly-4-methyl-1-pentene of the invention. Figure 6 is the thermal stability curve of isotactic poly-4-methyl-1-pentene. Figure 7 is the X-ray diffraction spectrum of syndiotactic poly-4-methyl-1-hexene. The stereoregularity of the syndiotactic polybutene obtained with the above-mentioned catalytic systems is evidenced by the 13 C NMR spectrum of the polymer (Fig. 1). The polymer crystallinity is shown in the X-ray diffraction spectrum (Cu Kα) which shows maxima of diffracted intensity for 2ϑ angles of 10.4°, 15.4° and 19.2° (Fig. 2). The stereoregularity of syndiotactic poly-4-methyl-1-pentene is evidenced by the 13 C NMR spectrum of the polymer (Fig. 3 and table 1). The polymer crystallinity is shown in the X-ray diffraction spectrum (Cu Kα) which shows maxima of diffracted intensity for 2ϑ angles of 9.75°, 13.9°, 17.0° and 18.4° (Fig. 4). In figures 5 and 6 are reported the thermal stability curves for the syndiotactic and isotactic polymer, respectively. The syndiotactic polymer, although it has a lower melting point, shows a thermal stability surprisingly superior to the one for the isotactic polymer. This makes the syndiotactic poly-4-methyl-1-pentene a polymer particularly suited for applications requiring a high thermal stability. The syndiotactic poly-4-methyl-pentene may also be obtained through hydrogenation of the syndiotactic poly-1,2-(4-methyl-1,3-pentadiene) prepared by using catalysts obtained from poly-methylalumunoxane and tetrabenzyl titanium. The stereoregularity of the poly-4-methyl-1-hexene is evidenced by the 13 C NMR spectrum of the polymers. The crystallinity is shown in the X-ray diffraction spectra (Cu Kα) which show maxima of diffracted intensity for 2ϑ angles of 8.9°, 12.75° and 16.5° (Fig. 7). The 13 C NMR spectra were done at 120°C. The samples were prepared by melting the polymers in tetrachloride-1,2-dideuteroethane. The chemical shift-scale refers to the hexamethyldisiloxane (δ = 0). The syndiotactic crystalline polymers of the invention find application in the field of thermoplastic materials. In particular, as already indicated, the 4-methyl-1-pentene polymers are suited for applications requiring elevated thermal stability. The following examples are given in order to illustrate the invention, without limiting the scope of same. Example 1 In a 100 ml glass autoclave were introduced under nitrogen atmosphere, 25 ml of toluene and 1 ml of a 10% by weight solution of polymethylaluminoxane (MAO) in toluene (Shering). It was cooled to 0°C, and 20 ml of 1-butene were introduced; then a mixture of 2 ml of MAO and 2 mg of isopropylidene-(cyclopentadienyl-1-fluorenyl)zirconium dichloride was added. The reaction mixture was agitated for 18 hours at 0°C. After treatment with acidified methanol and hydrochloric acid, filtration, washing with methanol and drying, 12.1 g of polymer were isolated; X-ray analysis showed that this polymer was crystalline (Fig. 2). Example 2 In a 50 ml glass reactor were introduced, under nitrogen atmosphere, 9 ml of MAO Shering solution (10% by weight), 3 mg of isopropylidene-(cyclopentadienyl-1-fluorenyl)zirconium dichloride and 15 ml of 4-methyl-1-pentene. The reaction mixture was agitated for 17 hours at 20°C. Operating according to the procedure of example 1, 7.5 g of polymer were isolated; an X-ray analysis showed that this polymer was crystalline (Fig. 4). By a differential thermal analysis the polymer showed a melt point of 196.6°C. Example 3 In a 50 ml glass reactor were introduced, under nitrogen atmosphere, 8 ml of toluene, 8 ml of 4-methyl-1-hexene and 5 ml of toluene solution containing 155 mg of polymethylalumoxane and 2.1 mg of isopropylidene-(cyclopentadienyl-1-fluorenyl)zirconium dichloride. The reaction mixture was agitated for 20 hours at 20°C. Operating according to the procedure of example 1, 1.61 g of polymer were isolated; X-ray analysis showed that this polymer was crystalline (Fig. 7). By a differential thermal analysis the polymer showed a melt point of 146.6°C. Example 4 (starting polymer for Example 5) 5 ml of benzene, 0.1 moles of 4-methyl-1,3-pentadiene, 0.6 mmoles of polymethylaluminoxane and 0.005 mmoles of titanium tetrabenzyl were introduced in a 250 ml vial at 20°C and maintained in contact for 72 hours at such temperature. 0.5 g of syndiotactic poly-1,2-(4-methyl-1,3-pentadiene) was obtained. Example 5 0.5 g of poly-1,2-(4-methyl-1,3-pentadiene), prepared according to the procedure of example 4, was dissolved in 50 ml of n-octane and 0.5 ml of 1,2,4-trichlorobenxene, and hydrogenated in an oscillating autoclave in the presence of 0.5 g of Pd supported on carbon (10% by weight) at 45 atm of hydrogen for 72 hours at a temperature of 150°C. The solution was then filtered on silica, and the hydrogenated polymer recovered by coagulation with ethanol. An X-ray analysis showed that this polymer was crystalline and a differential thermal analysis showed that it had a melt point of 196.5°C The average molecular weight of the polymer, obtained relative to polystyrene at 135°C in orthodichlorobenzene, was 176,000.

Claims: A crystalline syndiotactic polymer of 1-butene, 4-methyl-1-pentene or 4-methyl-1-hexene, wherein the recurring units are represented by: where R is CH 3 , n is an integer higher than 10. Poly-4-methyl-1-pentene according to claim 1, having a thermal stability greater than 98 % at temperatures up to 350°C. A polymerization process for preparing crystalline syndiotactic polymers of 1-butene, 4-methyl-1-pentene or 4-methyl-1-hexene, as defined in claim 1, said polymerization process being carried out in the presence of a catalyst system which comprises the reaction product of components A and B, wherein: A is an organometallic compound of the formula: or where n in formula 1 is 0 or an integer from 1 to 40 and in formula 2 is an integer from 2 to 40; R in both 1 and 2 is an alkyl, aryl, arylaklyl or cycloalkyl radical containing from 1 to 20 carbon atoms; and B is an organometallic compound of the formula: RMX 2 where R is an isopropylidene-(cyclopentadienyl-1-fluorenyl) group; M is Zr or Hf; X is halogen, hydrogen, alkyl, aryl, arylalkyl radical containing from 1 to 12 carbon atoms, -OR' (where R' is an alkyl, aryl, arylalkyl group containing from 1 to 12 carbon atoms), -OH, -CH 2 Si(CH 3 ) 3 radical, and the X substituents are the same or different. A manufactured article obtained from a polybutene of claim 1. A manufactured article obtained from the poly-4-methyl-1-pentene of claim 2. A manufactured article obtained from the poly-4-methyl-1-hexene of claim 1.

Inventors: ALBIZZATI ENRICO DR-BIOL, RESCONI LUIGI DR-CHEM, ZAMBELLI ADOLFO DR-CHEM, ALBIZZATI, ENRICO, DR.-BIOL., RESCONI, LUIGI, DR.-CHEM., ZAMBELLI, ADOLFO, DR.-CHEM.
Applicants: MONTELL TECHNOLOGY COMPANY BV
Application year: 1990
Main classification: C08F10
IPC codes: C08F110, C08F36, C08F4, C08F8, C08F10