JPH0366710A - Production of syndiotactic polypropylene - Google Patents

Abstract

PURPOSE:To obtain syndiotactic PP having a high bulk specific gravity in high yield per catalyst with hardly any change in the catalyst with time by polymerizing propylene in the presence of a specific transition metal catalyst and an aluminoxane copulverized with an inert carrier as a catalyst. CONSTITUTION:Propylene is polymerized in the presence of a transition metal catalyst [e.g. isopropyl(cyclopentadienyl-1-fluorenyl)hafnium dichlorde] having an asymmetric ligand and an aluminoxane [e.g. a compound expressed by formula I or II (R is 1-3C hydrocarbon residue; n is >=5] copulverized with an inert carrier (e.g. sodium oxide or magnesium oxide) used as a catalyst to provide the objective PP.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing syndiotactic polypropylene. Specifically, the present invention relates to a method for producing syndiotactic polypropylene with a high catalyst yield, a small change over time in the catalyst, and a high bulk specific gravity.

[Prior art]

The existence of syndiotactic polypropylene has been known for a long time, but the conventional low-temperature polymerization method using a catalyst consisting of a vanadium compound, ether, and organoaluminum has poor syndiotacticity, and the characteristics of syndiotactic polypropylene On the other hand, J. A. EWEN et al. reported that a syndiotactic pentad fraction of 0.8 was obtained using a catalyst consisting of a transition metal catalyst with an asymmetrical ligand and aluminoxane. It was discovered for the first time that polypropylene with superior toughness could be obtained (J.
,^m,chem,soc,,],988,110.6
255-6256).

[Problem to be solved by the invention]

The above-mentioned method by J, ^, EHEN et al. is an excellent method with good activity per transition metal and high toughness of the obtained polymer, but the particle size of the obtained polymer is small and the bulk specific gravity is low. It is small, the properties of the polymerization slurry are poor, and the polymerization heat cannot be removed, resulting in poor productivity.
Moreover, the catalyst is unstable, and a mixture of a transition metal catalyst and aluminoxane has a problem in that its activity decreases over time.

[! ! Means for Solving a Problem] The present inventors have made extensive studies on a method for solving the above problems and producing polypropylene with high activity and high syndiotacticity with good productivity, and have developed the present invention.

That is, the present invention provides a method for polymerizing propylene using a catalyst consisting of a transition metal catalyst having an asymmetrical ligand and aluminoxane, in which a transition metal catalyst having an asymmetrical ligand and aluminoxane are co-pulverized with an inert carrier. This is a method for producing syndiotactic polypropylene, which is characterized by using a syndiotactic polypropylene.

Examples of the catalyst used in the production of syndiotactic polypropylene in the present invention include the compounds described in the above-mentioned documents, but as long as a transition metal compound and aluminoxane having an asymmetrical ligand are used, even if they have different structures, the catalyst can be used to produce syndiotactic polypropylene. It is possible to utilize the method of the present invention even if the method differs from the above-mentioned document.

As a transition metal catalyst having an asymmetric ligand, isopropyl (cyclopentadienyl-1
-fluorenyl) hafnium dichloride, or isopropyl (cyclopentagenyl-1-fluorenyl)
Examples of aluminoxane include zirconium dichloride, and examples of aluminoxane include compounds represented by (wherein R is a hydrocarbon residue having 1 to 3 carbon atoms), and in particular, methylalanoxane where R is a methyl group and n is a hydrocarbon residue. 5 or more preferably 10
The above are used. The ratio of aluminoxane to the above transition metal catalyst is 10 to 1,000,000.
It is usually 50 to 5000 times by mole. Further, there are no particular limitations on the polymerization conditions, and solvent polymerization methods using an inert medium, bulk polymerization methods in which substantially no inert medium is present, and gas phase polymerization methods can also be used.

Generally, the polymerization temperature is -100 to 200°C, and the polymerization pressure is normal pressure to 100 kg/cd-G. Preferably -100~100°C1 normal pressure~50kg
/cd.

In the present invention, it is important to use the transition metal catalyst and the almonoxane co-pulverized with an inert carrier.

Any carrier can be used as long as it does not react with the above transition metal catalyst and aluminoxane to inactivate it, including sodium oxide, potassium oxide, magnesium oxide, calcium oxide, and aluminum oxide. Oxides of mono- to trivalent metals such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride,
Chlorides of mono- to trivalent metals such as alumina pentachloride, salts in which fluorine, bromine, iodine, etc. are substituted for chlorine, silica, alumina, or composite salts and composite oxides thereof can also be used. Preferably anhydrides are used here.

There are no particular restrictions on the method of co-pulverization, and methods using ball mills, rx mills, etc., which are usually used for the bottom of transition metal catalysts, can be used as they are. There is no particular restriction on the order of co-pulverization, and the transition metal compound, aluminoxane, and carrier may be co-pulverized at the same time, or the two components may be co-pulverized and then the remaining components may be added and co-pulverized. It is also possible to use various organic compounds as grinding aids as long as they do not decompose the catalyst components under co-grinding conditions. It is also possible to treat the co-pulverized product with a solvent. There are no particular restrictions on the temperature during co-grinding.
0 to 100″C5 Normally, it may be carried out at a temperature around room temperature.

Examples of solvents used during polymerization or treatment include saturated hydrocarbon compounds such as propane, pentane, hexane, heptane, octane, nonane, decane, cyclopentane, and cyclohexane, as well as aromatic hydrocarbons such as benzene, toluene, and xylene. Compounds are also available.

〔Example〕

The present invention will be further explained with reference to Examples below.

Example 1 2 g of isopropyl (cyclopentajenyl-1-fluorenyl) zirconium dichloride obtained by lithiation of isopropylcyclopentagenyl-1-fluorene that had bottomed out according to a conventional method and reacting with zirconium tetrachloride and anhydrous Magne chloride 99120g and Toyo Akzo■
1.5g of methylaluminoxane (degree of polymerization: 16.1)
A vibrating pot (inner volume of pot 1000 m, diameter 12.7
The mixture was co-pulverized for 34 hours using a 2 kg SUS ball (mm).

29+mg of co-pulverized product (equivalent to 2,4+*g of isopropyl(cyclopentagenyl-l-fluorenyl)zirconium dichloride, 1.8μ of methylaluminoxane)
11 toluene was charged into an autoclave with a volume of 21 using 0.15 g of methylaluminoxane and propylene were added to make 3 kg/d-c, and polymerization was carried out at 20°C for 2 hours while maintaining the temperature at 3 kg/c4-G. After that, the slurry was taken out, filtered and dried, and 1 part of syndiotactic polypropylene was added.
09.8g was obtained. From the filtrate, 3.3 g of a component soluble in toluene (according to infrared absorption spectrum, it is acidic polypropylene) was obtained. The intrinsic viscosity (hereinafter abbreviated as η) of the powder measured in a tetralin solution at 135°C is 1.4, and the syndiotactic pentad fraction is 0.
．． It was 92. Furthermore, when 1 g of this co-pulverized material was dispersed in 10 ml of hexane and stored for 24 hours, polymerization was carried out in the same manner to obtain 102.5 g of toluene-insoluble matter and 3.2 g of toluene-soluble matter.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1, except that 3 and 0.16 g of methyl alkyl fuxane were used without supporting a transition metal catalyst. After about 1 hour and 10 minutes, there was no need to add propylene at all, and the temperature started to rise, but this was resolved by lowering the temperature of the cooling water. After polymerization, I tried to take out the obtained slurry, but I could not take it out as it was. II! ,
of toluene was added to dilute it and taken out. 68.3 g as insoluble part in toluene, 4.2 g as soluble part
Met. The powder had an η of 1.37 and a syndiotactic pentad fraction of 0.92. Further, when 1 g of this co-pulverized material was dispersed in 10-hexane and stored for 24 hours, the toluene insoluble content was 40.
5g.

4.1 g of toluene soluble content was obtained.

Example 2 The same procedure as Example 1 was carried out except that silica gel heat-treated at 300°C (pulverized for 48 hours with a vibration mill) was used as a carrier. 98.8 g of powder and 3.0 g of luene-soluble matter were obtained. The powder had an η of 1.39 and a syndiotactic pentad fraction of 0.92.

In addition, 1 g of this co-pulverized material was dispersed in 10-hexane and 24
Polymerization was carried out in the same manner using a sample that had been stored for some time, yielding 95.7 g of toluene-insoluble matter and 3.1 g of toluene-soluble matter.

[Effects of the Invention] By carrying out the method of the present invention, syndiotactic polypropylene can be obtained with high activity per catalyst, which is extremely valuable industrially.

Claims (1)

[Claims] In a method for polymerizing propylene using a catalyst consisting of a transition metal catalyst having an asymmetrical ligand and aluminoxane, it is possible to use a transition metal catalyst having an asymmetrical ligand and aluminoxane co-pulverized with an inert carrier. Characteristic method for producing syndiotactic polypropylene.