Process for producing .alpha.-olefin polymers using novel catalyst system

[54] PROCESS FOR PRODUCING a-OLEFIN POLYMERS USING NOVEL CATALYST SYSTEM

[75] Inventors: Akinobu Shiga, Koganei; Toshio Sasaki, Ichihara; Junpei Kojima, Ichihara; Akira Nunose, Ichihara, all of Japan

[73] Assignee: Sumitomo Chemical Company, Limited, Osaka, Japan

[21] Appl. No.: 631,177

[22] Filed: Jul. 16, 1984

[30] Foreign Application Priority Data

Jul. 27, 1983 [JP] Japan 58-138471

[51] Int. Cl.« C08F 4/64

[52] U.S. CI 502/112; 502/107;

502/108; 502/119; 526/137 [58] Field of Search 502/119, 112, 108, 107

[56] References Cited

U.S. PATENT DOCUMENTS

3,135,809 6/1964 Bosmajian 502/103 X

4,165,298 8/1979 Shiga et al 502/112 X

4,309,521 1/1982 Sato et al 502/108 X

4,325,837 4/1982 Capshew et al 502/108

Primary Examiner—Patrick P. Garvin

Attorney, Agent, or Firm—Stevens, Davis, Miller &

Mosher

[57] ABSTRACT

A process for producing an a-olefin polymer which comprises polymerizing an a-olefin in the presence of a catalyst system comprising

(A) a solid catalyst component obtained by steps of

(i) reducing titanium tetrachloride with an organoaluminum compound represented by the general formula ... wherein R1 represents a Ci-Cis hydrocarbon group, Y represents a halogen, and n represents a number satisfying l<n<3,

(ii) heating the reduction product at a temperature of up to 150° C,

(iii) treating the thus obtained solid product containing y-titanium trichloride by preliminary polymerization of an a-olefin in the presence thereof, and

(iv) reacting the resulting solid product with a halogen represented by the general formula X2, wherein X represents CI, Br, or I, and/or an interhalogen compound represented by the general formula X'X"a, wherein X' and X" represent each CI, Br, or I and represents 1 or 3, and with an ether compound represented by the general formula R2—O—R3, wherein R2 and R3 are the same or different and represent each a Cj-Cio alkyl group, in a hydrocarbon solvent at a temperature of 50° to 100° C, and

(B) an organoaluminum compound.

8 Claims, 1 Drawing Figure

PROCESS FOR PRODUCING a-OLEFIN POLYMERS USING NOVEL CATALYST SYSTEM

BACKGROUND OF THE INVENTION 5

The present invention relates to a novel catalyst system using a novel solid catalyst component for the polymerization of a-olefins and a process for producing a-olefin polymers using such catalyst system.

Catalyst systems comprising titanium trichloride and 10 an organoaluminum compound have hitherto been used for the industrial production of high crystalline polymers of a-olefins such as propylene, butene-1, etc. Since the polymerization proceeds in such a state that a solid titanium trichloride is embraced by the formed poly- 15 mer, the titanium trichloride partly remains in the product polymer. This residue causes adverse effects on the color, heat stability, and other properties of the polymer. Hence, an extraction step was generally necessary to remove the residue from the polymer. On the other 20 hand, an amorphous polymer called "atactic polymer" is incidentally produced in the polymerization. When remaining in the product polymer, said atactic polymer deteriorates mechanical properties of molded products of the polymer and may give stickiness thereto. This 25 required generally a washing step for removing the atactic polymer from the objective polymer.

These additional operations resulted in economical disadvantages with respect to materials and energy, so that a simplified process was intensively desired. Up to 30 now, various improvements have been made in the preparation of titanium trichloride. As a result, the polymerization activity and/or stereospecificity of the catalyst were greatly improved and this enabled the industrialization of polymerization processes simplified 35 with respect to the above-said operations. The present inventors disclosed formerly such an improved process for preparation of titanium trichloride in Japanese Patent Publication No. 27085/80 and subsequently a further improvement of this process in Japanese Patent 40 Application Kokai (Laid-Open) No. 116706/81. However, when the solid product obtained by reducing titanium tetrachloride with an organoaluminum compound or the heat-treated material of said solid product was used as a titanium trichloride composition as de- 45 scribed in the above patents, parts of these titanium trichloride composition particles were disintegrated into fine particles during the activation treatment of the composition with a halogen compound-ether compound mixture or with a halogen compound-ether com- 50 pound-electron donative compound mixture, resulting in a great difficulty of filtration in the washing of the activated composition. This obliged the use of the decantation method, which was inferior in the effect of solid-liquid separation. Additionally, on drying the 55 washed composition, a great number of stiff agglomerates were produced therefrom. When said titanium trichloride composition was used as such for the polymerization of olefin, there were fears of clogging of the solid-catalyst feed line was such agglomerates and of 60 the polymer discharge valve with polymer blocks formed in the polymerization reactor. It was therefore necessary to remove the agglomerates by sieving or the like.

There have been proposed some methods in order to 65 prevent the disintegration of titanium trichloride particles during the activation treatment. The proposed methods comprise polymerizing a small amount of a

2

olefins on a /3-titanium trichloride-containing solid product obtained by reducing titanium tetrachloride with an organoaluminum compound, prior to the activation treatment of this solid product (Japanese Patent Application Kokai (Laid-Open) Nos. 58206/80, 145117/81, and 5314/83). According to these methods, the disintegration of titanium trichloride particles is surely prevented, but coarse particles of the catalyst are formed by agglomeration particularly when propylene is preliminarily polymerized on the catalyst or when the activation treatment is conducted in an aromatic hydrocarbon solvent.

As a result of intensive studies, the present inventors found a novel catalyst system using a novel solid catalyst component for a-olefin polymerization, which is highly active, highly stereospecific, and good in particle character. Said solid catalyst component is prepared by the reduction of titanium tetrachloride with an organoaluminum compound, heat treatment of the reduction product, preliminary polymerization of a-olefin to treat the thus obtained solid product containing y-titanium trichloride, and activation treatment of the preliminary polymerization treated product with a halogen and/or an interhalogen compound and with an ether compound. Based on this finding, this invention has been accomplished.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a novel solid catalyst component for the polymerization of a-olefins.

Other object of the present invention is to provide a process for producing an a-olefin polymer in the presence of a catalyst system using said solid catalyst component.

Other objects and advantages of the present invention will become apparent from the descriptions below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanied drawing, numerals 1, 2 and 3 show X-ray diffraction spectra of the y-titanium trichloride-containing solid products of Example 1, Comparative Example 2 and Example 3, respectively.

These X-ray diffraction spectra were obtained by using the Cu-Ka ray. In the drawing, the scale of abscissa indicates the double (20) of the diffraction angle and the scale of ordinate indicates the intensity of the spectral line.

DETAILED DESCRIPTION OF THE
INVENTION

According to the present invention, there are provided a solid catalyst component for the polymerization of a-olefins obtained by steps of

(i) reducing titanium tetrachloride with an organoaluminum compound represented by the general formula RlnAlY3_n, wherein R1 represents a Ci-Cis hydrocarbon group, Y represents a halogen, and n represents a number satisfying 1 < n < 3,

(ii) heat-treating the reduction product at a temperature of up to 150° C,

(iii) treating the thus obtained solid product containing y-titanium trichloride, by preliminary polymerization of an a-olefin in the presence thereof, and

(iv) reacting the resulting solid product with a halogen represented by the general formula X2, wherein X represents CI, Br, or I, and/or an interhalogen com4,554,

3

pound represented by the general formula X'X"a, wherein X' and X" represent each CI, Br, or I and a represents 1 or 3, and with an ether compound represented by the general formula R2—O—R3, wherein R2 and R3 are the same or different and represent each a 5 Ci-Cioalkyl group, in a hydrocarbon solvent at a temperature of 50° to 100° C, and a process for producing an a-olefin polymer which comprises polymerizing an a-olefin in the presence of a catalyst system comprising (A) the thus obtained solid catalyst component and (B) 10 an organoaluminum compound.

According to the present invention, a highly active and highly stereospecific catalyst system using a solid catalyst component almost completely free of too fine and too large particles for a-olefin polymerization can 15 be obtained by a preliminary propylene polymerization treatment of the y-titanium trichloride-containing solid product, even if followed by severe conditions of treatment such as treating the resulting solid product with mixture of halogen and/or an interhalogen compound 20 and with an ether compound in an aromatic solvent at a high temperature. In consequence, the catalyst system of this invention is characterized by providing an a-olefin polymer excellent in particle character, free of too fine and too large particles. 25

The organoaluminum compound used in the present invention for reducing titanium tetrachloride is represented by the general formula ... In the formula; R1 represents a Ci-Cis hydrocarbon group, preferably Ci-Cs hydrocarbon group, particularly prefera- 30 bly C2-C4 linear or branched hydrocarbon group; Y represents a halogen, preferably CI; and n represents a number satisfying l<n<3, preferably l<nS2. Examples of the organoaluminum compound are methyl aluminum sesquichloride, ethylaluminum sesquichloride, 35 isobutylaluminum sesquichloride, dimethylaluminum chloride, diethylaluminum chloride, diethylaluminum bromide, diethylaluminum iodide, di-n-propylaluminum chloride, di-n-bytylaluminum chloride, diisobutylaluminum chloride, and mixtures of these compounds. 40 Among these, preferred are diethylaluminum chloride, ethylaluminum sesquichloride, a mixture thereof and mixtures of ethylaluminum sesquichloride with ethylaluminum dichloride, and particularly preferred is ethylaluminum sesquichloride. 45

The reduction of titanium tetrachloride is favorably carried out in an inert hydrocarbon solvent, particularly in an aliphatic hydrocarbon solvent such as hexane or heptane, at a temperature of —50° to 50° C, particularly — 30° to 30° C. For instance, the reduction is preferably 50 carried out by adding a solution of an organoaluminum compound in an inert hydrocarbon to a solution of titanium tetrachloride in an inert hydrocarbon in limited amounts so as to keep the mixed system at a prescribed temperature. Suitable concentrations of titanium tetra- 55 chloride and the organoaluminum compound in the respective inert hydrocarbon solutions are both 20 to 80%, particularly 30 to 60%, by weight. Suitable molar ratios of the organoaluminum compound represented by the formula R'„AlY3_„to titanium tetrachloride for 60 the reaction are n_1 to 2x(n—1)_1: 1, particularly lX(n-l)-' to 1.5x(n—l)-1! 1 (herein the number of moles of the organoaluminum compound is calculated on the assumption that the compound is in monomeric form). Preferably, the reduction is carried out under 65 moderate agitation. After mixing titanium tetrachloride with an organoaluminum compound, the agitation is desired to continue for 15 minutes to 6 hours at a tern

,264

4

perature within the above-mentioned range to complete the reduction. Thus a suspension of the reduced solid is obtained.

Then the y-titanium trichloride-containing solid product is prepared by heat treatment of the reduced solid. The y-titanium trichloride-containing solid product in this invention is a titanium trichloride composition giving an X-ray diffraction spectrum in which the intensity of the spectral line (diffraction peak height) due to the lattice spacing d = 5.43 A is up to 50%, preferably up to 40%, of the intensity of the spectral line (diffraction peak height) due to the lattice spacing d=5.83A. When the former intensity is higher than 50% of the latter, particles of such a solid product agglomerate into large particles in the activation treatment step, and the resulting solid catalyst component indicates low activity and poor stereospecificity.

The heat treatment is carried out preferably by using the suspension of the reduced solid as such though feasible after separation of the reduced solid from the suspension liquid and washing the solid with an inert hydrocarbon solvent. The suspension of the reduced solid can be heat-treated at a temperature of up to 150° C, preferably 70° to 130° C, particularly 75° to 110° C. Optimum temperatures of the heat treatment depend upon the organoaluminum compound used for the reduction. For instance, the optimums are 75° to 100° C. for ethylaluminum sesquichloride and 80° to 110° C. for diethylaluminum chloride. Suitable periods of the heat treatment are 15 minutes to 6 hours, particularly 30 minutes to 4 hours. Thus the y-titanium trichloride-containing solid product can be obtained.

The y-titanium trichloride-containing solid product obtained as described above can be subjected as such, without isolating from the liquid, to the preliminary a-olefin polymerization treatment under certain polymerization conditions without adding any organoaluminum compound. Preferably, the preliminary polymerization treatment is carried out on the y-titanium trichloride-containing solid product which has been separated from the suspension liquid after completion of the heat treatment, and washed several times with an inert hydrocarbon solvent such as hexane or heptane. That is, the preliminary polymerization treatment is accomplished by suspending 10 g of the y-titanium trichloridecontaining solid product in 20-200 ml of an inert hydrocarbon solvent such as hexane or heptane, adding 0.1-20 g of the same organoaluminum compound as will be used for the main polymerization, and polymerizing an a-olefin at a temperature of 25° to 80° C., preferably 30° to 60° C, under a gage pressure of 0 to 10 kg/cm2, generally for 5 minutes to 4 hours. In the preliminary polymerization, hydrogen may be added to regulate the molecular weight. Suitable amounts of the a-olefin preliminary polymerized are 0.01 to 5 g, particularly 0.03 to 1 g, per 1 g of the y-titanium trichloride-containing solid product. Ethylene or propylene is used as a-olefin for the preliminary polymerization treatment. Propylene gives better results. After completion of the preliminary polymerization treatment, the resulting solid product is separated from the liquid medium and washed several times with an inert hydrocarbon solvent such as hexane, heptane, cyclohexane, methylcyclohexane, toluene, or xylene.

The solid product obtained by the preliminary polymerization treatment (hereinafter referred to as the preliminary polymerization treated solid) is then re