WO2001044313A1

WO2001044313A1 - Preparation method of supported catalyst for polymerization of ethylene and co-polymerization of ethylene/alpha-olefin

Info

Publication number: WO2001044313A1
Application number: PCT/KR2000/001456
Authority: WO
Inventors: Ho-Sik Chang; Sung-Gun Roh; Gyo-Hyun Hwang
Original assignee: Samsung General Chemicals, Ltd.
Priority date: 1999-12-14
Filing date: 2000-12-13
Publication date: 2001-06-21
Also published as: KR20010056057A; KR100436494B1

Abstract

A preparation method of catalyst for polymerization of ethylene and co-polymerization of ethylene and alpha-olefin is provided. The preparation method of catalyst of the present invention comprises a) producing a carrier by reacting organic magnesium compound of MgPh2.nMgCl2.mR2O (wherein Ph=phenyl, n=0.37∩0.7, m≥1, R2O=ether) with organic chlorine compound and silicon compound at -20∩80 °C, wherein the molar ratio of organic chlorine compound to Mg is 0.5 or more, and the molar ratio of silicon compound to Mg is 0.001 or more; b) treating said magnesium containing carrier with titanium compound.

Description

PREPARATION METHOD OF SUPPORTED CATALYST FOR POLYMERIZATION OF ETHYLENE AND CO-POLYMERIZATION OF ETHYLENE/ALPHA-OLEFIN

Technical Field

The present invention relates to a preparation method of catalyst for polymerization of ethylene and co-polymerization of ethylene and alpha-olefin, and in particular, to a preparation method of supported catalyst containing titanium compound on the carrier, which contains magnesium and has narrow particle size distribution.

Background of the invention

The preparation method of supported catalyst for polymerization of ethylene and co-polymerization of ethylene and alpha-olefin by reacting organic magnesium compound of composition MgPh₂.nMgCl2.mR₂0 (wherein Ph=phenyl, n=0.37-0.7, m> 1 , R₂θ=ether) with organic halide, and then covering obtained carrier with transition metal compound such as TiCl₄, VC1₄ or VOCI3, by using the method of covering transition metal compound on the carrier, has been disclosed by the applicant of the present inventionUapanese Patent Application No. 330675/1995).

However, although the catalyst produced by the above method, especially the catalyst obtained by the method of covering TiCl₄ on the carrier, has narrow particle size distribution and high bulk density and achieved partial improvement in polymerization process, it still has the disadvantage that the distribution of the molecular weights is not still sufficiently narrow, and high initial catalytic activity and particle size control is still difficult to achieve.

It is known that, for polymer with narrow⁷ molecular weight distribution, especially linear low density polyethylene product produced by co-polymerization of ethylene and alpha-olefin, the quality of the product can be enhanced since the amount of low molecular weight polymer which can be extracted by hexane is reduced. The size of the polymerized polymer particle should be controlled easily for the stability of polymerization process and application of the product. It is well known that polyethylene particle of proper size can affect on the transfer of particles by air and on the productivity of extruder in the process after polymerization.

For these purposes, the method of preparing catalyst with uniform active site that can get narrow molecular weight distribution, and the method of controlling polymer particle size as needed in the application of the product or in the polymerization process is demanded.

Objects of the invention

The object of the present invention is to provide a method of manufacturing polymers with narrow molecular weight distribution and higher bulk density, and to provide the preparation method of catalyst for polymerization of ethylene, and co-polymerization of ethylene and alpha-olefin in slurry and gas phase polymerization in which polymer particle size is easily controlled for the productivity of polymerization process and for various application.

Detailed description of the Preferred Embodiments

According to the present invention, the preparation method of catalyst is characterized by treating the carrier obtained by reacting organic magnesium compound MgPh2.nMgCl .mR₂θ(wherein Ph=phenyl, n=0.37-0.7, m 1 , R₂θ=ether) with mixture of organic chlorine compound and silicon compound, with titanium compound. In the following, the present invention w⁷ill be described in detail.

According to the preparation method of catalyst of the present invention, organic magnesium complex agent [MgPh9.nMgCl₂.mR₂O] which forms a solution dissolved in solvent chlorobenzene, ether(R₂θ), or the mixture of chlorobenzene and ether, or the mixture of chlorobenzene and aliphatic or aromatic compound is used in the step of producing magnesium containing carrier. And, carrier containing powder organic magnesium suspended in the hydrocarbon solution is produced by reacting said solution of organic magnesium compound with organic chlorine compound and silicon compound with a molar ratio of (organic chlorine compoundVMg ≥ 0.5 and (silicon compoundVMg≥ 0.001 at the temperature of - 20-80 ^°C .

Preferably, the mixture of silicon ethoxide, with the molar ratio of

(silicon compoundVMg≥ 0.001 , and carbon tetrachloride, with mole ratio of (organic chlorine compoundVMg ≥ 0.5, are reacted. Carrier obtained by said method has narrow distribution of particle size. The size of carrier and catalyst particles can be controlled within 5- 150 m by the molar ratio of silicon compound to magnesium, and the reaction condition of organic magnesium compound and organic chlorine compound. The magnesium containing carrier obtained by the said method includes mainly magnesium dichloride(80~90 weight%), ether(7~15 weight%), siliconOess than 1 weight%) and hydrocarbon complex compoundd — 5 weight%).

In the present invention, organic magnesium compound used in the production of magnesium containing carrier is produced by reacting powder magnesium with chlorobenzene in the presence of one or more of electron donor, wherein the electron donor can include aliphatic or cyclic ether. Aliphatic ether, which has chemical formula of R2OR3, wherein R2 and R3 can be the same or different alkyl radical having 2-8 of carbons, preferably having 4-5 carbon atoms. Cyclic ether has the carbon numbers of 3-5. The most preferred electron donors are dibutylether or diisoamylether.

For the organic chlorine compound of the present invention, it is preferable to use compound of general formula CR'_nCl(₄-_n)(wherein n is an integer between 0 and 3) wherein R' is alkyl radical having carbon number of 1- 12, and most preferred organic chlorine compound is carbon tetrachloride.

Silicon compound of the present invention has the general formula of Si(OR)_aX4-_a» wherein R stands for aliphatic or aromatic hydrocarbon group with carbon number of 1 - 14 or COR' (wherein R' is aliphatic or aromatic hydrocarbon group with carbon number of 1 - 14), X for Cl, Br or I, and a for 0, 1 , 2, 3 or 4. Preferably, the silicon compound is silicon alkoxyde such as S OC₂H5V , Si(OC₂H5)2Cl_{2 >} Si(OC₂H₅)Cl₃ or Si(OC₂H₅)₃Cl.

Organic chlorine compound and silicon compound can be reacted with organic magnesium compound to produce carrier by one of following five methods. The first method is reacting organic magnesium compound with a mixture of silicon compound and organic chlorine compound. The second method is reacting organic magnesium compound and organic chlorine compound, and after certain time, introducing a solution of mixed silicon compound and organic chlorine compound to react with the organic magnesium compound. The third method is mixing silicon compound and organic magnesium compound, and then organic chlorine compound is introduced to react with the organic magnesium compound. The fourth method is introducing silicone compound after the reaction between organic magnesium compound and organic chlorine compound. And the last method is introducing silicone compound after the titanium compound treatment. Among these five methods, the first method is preferred.

The catalyst of the present invention is produced by treating magnesium containing carrier obtained by the above method with titanium compound, with the molar ratio of Ti/Mg=0.01 -2.0, preferably 0.04-0.5 at the temperature of 20~ 100^°C , preferably 40-80 ^°C , in the hydrocarbon solvent.

The catalyst of the present invention, if needed, can be produced by treating magnesium containing carrier obtained by the above method with titanium compound, mixed with silicon with the molar ratio of Si/Ti=0.1 ~2.0, preferably 0.5- 1.0, and Ti/Mg=0.01 ~2.0, preferably 0.04-0.5 at the temperature of 20~ 100 ^°C , preferably 40~80^°C , in the hydrocarbon solvent.

The titanium compound used in the present invention has general formula of Ti(OR)_aX4-a, wherein R stands for aliphatic or aromatic hydrocarbon group with carbon number of 1 - 14 or COR'(wherein R' is aliphatic or aromatic hydrocarbon group with carbon number of 1 — 14), X for Cl, Br or I, and a for 0, 1 , 2 or 3. Preferred titanium compounds can include TiCl₄ or titanium alkoxychloride such as Ti(OC₃H₇)2Cl2, Ti(OC₃H₇)Cl₃, Ti(OC₃H₇)₃Cl, Ti(OC₄H₉)2Cl₂, Ti(OC₄H₉)Cl₃ or Ti⁽OC₄H₉)₃Cl. When the molar ratio of Ti/Mg is greater than 2.0, excessive titanium compounds that are not fixed on the supporter(carrier) need to be removed in washing process, and treat of the waste costs high and difficult due to the toxicity and corrosiveness of titanium compounds. When the molar ratio of Ti/Mg is less than 0.01 , there is a problem of insufficient low catalytic activity.

Carrier, if needed, can be treated with organic aluminum compound with the molar ratio, before washing, of Al/Ti=0.1 -2.0, before being treated with titanium or, after catalyst production, preferably the molar ratio of Al/Ti=0.5- 1.5 at 30~80^°C . Excessive use of organic aluminum has the disadvantage of generating fine particles due to the destruction of carriers. Organic aluminum compound used herein is organic alkyl aluminum or organic aluminum halogen compound having the formula of AIR' _n 3-_n- wherein R' stands for alkyl group with 1 - 16, preferably 2- 12 of carbons, X for a halogen compound such as chlorine or bromide and n for an integer or fraction between 0 and 3. Examples of organic aluminum compounds are trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trihexyl aluminum, trioctyl aluminum, ethyl aluminum chloride, methyl aluminum chloride, ethyl aluminum sesquichloride, isobutyl aluminum sesquibromide, dimethyl aluminum chloride, diethyl aluminum chloride, diethyl aluminum bromide, diethyl aluminum iodide, di-n-propyl aluminum chloride, di-n-butyl aluminum chloride, diisobutyl aluminum chloride, di-n-octyl aluminum iodide, methyl aluminum dichloride, ethyl aluminum dichloride, isobutyl aluminum dichloride and n-butyl aluminum dichloride. The most preferable organic aluminum compound is selected from the group comprised of dialkyl aluminum chloride and ethyl aluminum sesquichloride. The above preparation method of catalyst of the present invention provides methods for catalyst with high activity, narrow particle size distribution and various average particle sizes, that can be useful for many applications.

According to the present invention, for example, catalyst with particle size of 5- 10// m or 10- 15// m which is useful for ethylene slurry polymerization, and catalyst with particle size of 25- 150 / m which is useful for gas phase ethylene polymerization can be produced. By using substance containing silicon compound as a component of carrier, polyethylene with relatively narrow molecular weight distribution can be obtained compared to the one produced by magnesium carrier which does not contain silicon compound. Narrow molecular weight distribution(MWD) may be characterized by MWD<6, measured by gel permeation chromatography, and titanium supported catalyst containing silicon compound of the present invention is appropriate in obtaining polyethylene and polyethylene co-polymer with 2.5<MWD<4.

The catalyst of the present invention can be used in the polymerization of ethylene or co-polymerization of ethylene and alpha-olefin. The catalyst of the present invention can be used together with one or more of organic aluminum compound as a cocatalyst, preferably trialkyl aluminum.

Organic aluminum compound which can be used as a cocatalyst has the formula of AlR_nX₃-_n, wherein R stands for alkyl radical with carbon number of 1- 12, X for hydrogen atom or halogen atom such as Cl or F, or alkoxy radical with carbon number of 1 — 12, and n for an integer or fraction thereof between 1 — 3. For example, triisobutyl aluminum, triethyl aluminum, trimethyl aluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum, ethyl aluminum sesquichloride and diethyl aluminum chloride can be used.

Polymerization is carried out by slurry polymerization in the hydrocarbon solvent(such as nucleic acid, heptane) at 50~ 100 ^°C , or by gas phase polymerization at 60~200^°C under 2~40atm. As a control agent of molecular weight of polymer, hydrogen(5~90 volume%) is used. Propylene, butene- 1 , hexene- 1 , 4- methylpentene- 1 , and other alpha-olefin can be useful in the co- polymerization of ethylene and alpha-olefin.

In the following, the present invention is described in detail through examples and comparative examples. The following examples, however, are not intended to restrict the scope of the present invention. Comparative example 1

A. Production of organic magnesium compound In the 1/ of reactor equipped with stirrer and temperature controller, 29.2g of magnesium powder (1.2mole) and 436m/ of chlorobenzene(4.3mole) are reacted in the presence of solution of 307«?/ of dibutylether(l .δmol) and Ami of buttylchloride with 0.29g of iodide dissolved, as an activator. Reaction is carried out in the inert gas(N) atmosphere at 80- 100 ^°C with stirring for 10 hours. Then the mixture is maintained for 12 hours without stirring and then liquid phase is isolated from the sediments. Liquid phase is a solution of organic magnesium compound of composition

MgPh₂.0.5MgCl2.2(C4Hg)₂θ dissolved in the chlorobenzene (with Mg 0.92mole/ /).

B. Production of carrier

120ml of the solution(0.11mole of Mg) obtained from the step A is introduced to the reactor equipped with stirrer, and 10.6ml of CCLtCO. l lmole CCL) dissolved in the 42ml of n-hexane is added to the reactor at 50 ^°C over an hour. Reacted mixture is stirred for 6 minutes at the same temperature, and then solvent is removed and sediments are washed four times with 100m/ of n-hexane at 60 ^°C . As a result, 11.8g of organic magnesium carrier in powdered form is obtained suspended in the n-hexane.

C. Production of catalyst

To the n-hexane suspension of organic magnesium carrier obtained, is added titanium alkoxy chloride with the molar ratio of Ti/Mg=0.25 obtained by mixing 1.5m/ of TiCL and 3.8m/ of titanium propoxyde(Ti(OCsHδ)4), and reacted mixture is heated to 60^°C , and then solid sediments obtained by stirring for 2 hours is washed with 100m/ of n-hexane 4 times at 60 ^°C . Average particle size of the catalyst is 55// m.

<Polymerization> Polymerization of ether is carried out in the 2/ of steel reactor with stirrer and temperature control jacket. As a hydrocarbon solvent, n-hexane(1000m/) is used, and as a cocatalyst 2rnrnol of

AKEO₃ is used. Polymerization is carried out at 7.5 atm of ethylene pressure and 4.5atm of hydrogen pressure at 80 ^°C for an hour.

Catalyst corresponding to O.Ol δmmol of titanium was taken into this experiment. The catalytic activity was 12.5kg polyethlene per lg of titanium, per hour and ethylene pressure. Melting index(MI) of polyethylene was 8.9g/10min under 2.16kg weight and at 190^°C , and the ratio of melting index of 21.6kg to 2.16kg was 30. Bulk density of the polyethylene powder was 0.32g/cm³, and had narrow particle size distribution. SPAN calculated from molecular body analysis data by the following formula was less than 0.6. The result of ethylene polymerization is shown in table 1. SPAN = (d90 - dlOVdδO, wherein d90, d50 and dlO means polyethylene particle size with 90, 50 and 10 weight %, respectively.

Example 1

In step B of comparative example 1 , mixture of 1.5m/ of silicon ethoxyde (Si(OC₂H₅)4)(0.007mol) and 10.6m/ of CC1₄ is added with the molar ratio of CCU/Mg=1.0, Si/Mg=0.06 to produce catalyst, instead of using organic magnesium compound and 10.6m/ of CCLW. l lrnole CCI₄) dissolved in the 42m/ of n-hexane, other processes being equal as in the comparative example 1. The result of ethylene polymerization is shown in table 1.

Example 2

In example 1 , the mole ratio of Si/Mg is 0.03 and 3.0m/ of T1CI₄ is used to produce catalyst instead of using mixture of 1.5m/ of TiCl₄ and 3.8m/ of titanium propoxide^ OCsHsV), others being equal as in the example 1. The polymerization process is the same as example 1.

The result of ethylene polymerization is shown in table 1.

Example 3 Using the catalyst obtained in example 2, co-polymerization of ethylene and 1-hexene is carried out. The polymerization process is the same as example 1 except that 150cc of 1-hexane is used before polymerization. As a result, co-polymer of ethylene and 1-hexene of density 0.945g/cc is produced. The result of polymerization is shown in table 1.

Table 1

*unit: Kg-PE/gTi. ethylene 1 atm.hr **MI 2.16 : melting index under weight 2.16kg and at 190^°C MI 21.6 : melting index under weight 21.6kg and at 190 ^°C ***MFRR : ratio of MI 21.6 to MI 2.16

The effect of the invention

As shown above, the preparation method of catalyst of the present invention provides highly active catalyst for producing polyethylene resin, which has various particle size depending on the molar ratio of organic silicon compound and magnesium, with narrow particle size distribution.

Claims

ClaimsWhat is claimed is:

1. A method for producing a catalyst for polymerization of ethylene and co-polymerization of ethylene and alpha-olefin, comprising: a) producing a carrier by reacting organic magnesium compound of MgP_i₂.nMgCl2.mR₂θ(wherein Ph=phenyl, n=0.37~0.7, m ≥ 1 , R₂θ=ether) with organic chlorine compound and silicon compound at -20-80 ^°C , wherein the molar ratio of organic chlorine compound to Mg is 0.5 or more, and the molar ratio of silicon compound to Mg is 0.001 or more; b) treating said magnesium containing carrier w^rith titanium compound.

2. The method according to Claim 1 , wherein the reaction of the organic magnesium compound with the organic chlorine compound and the silicon compound is performed by reacting organic magnesium compound with a mixture of silicon compound and organic chlorine compound.

3. The method according to Claim 1 , wherein the reaction of the organic magnesium compound with the organic chlorine compound and the silicon compound is performed by reacting the organic magnesium compound and the organic chlorine compound, and after certain time, introducing a solution of mixed silicon compound and organic chlorine compound to react with the organic magnesium compound.

4. The method according to Claim 1, wherein the reaction of the organic magnesium compound with the organic chlorine compound and the silicon compound is performed by mixing the silicon compound and the organic magnesium compound, and then the organic chlorine compound is introduced to react with the organic magnesium compound.

5. The method according to Claim 1 , wherein the reaction of the organic magnesium compound with the organic chlorine compound and the silicon compound is performed by introducing the silicone compound after a reaction of the organic magnesium compound and the organic chlorine compound.

6. A method for producing a catalyst for polymerization of ethylene and co-polymerization of ethylene and alpha-olefin, comprising: a) producing a carrier by reacting organic magnesium compound of MgPr_2.nMgCl₂.mR₂θ(wherein Ph=phenyl, n=0.37~0.7, m ≥ 1 , R₂θ=ether) with organic chlorine compound at -20~80^°C , wherein the molar ratio of the organic chlorine compound to Mg is

0.5 or more! and b) treating said carrier with titanium compound, and then introducing silicone compound, wherein the molar ratio of silicon compound to Mg is 0.001 or more.

7. The method according to any of Claims 1 to 6. wherein said organic magnesium compound is produced by reacting metal magnesium with chlorobenzene in the presence of dibutylether or diisoamylether.

8. The method according to any of Claims 1 to 6, wherein said organic chlorine compound has general formula CR'_nCl(4-_n)(wherein R' is alkyl radical of carbon number 1 - 12 and " n" is an integer in the range of 1 -3)

9. The method according to Claim 8, wherein said chlorine compound is carbon tetrachloride.

10. The method according to any of Claims 1 to 6, wherein said silicon compound has the general formula of Si(OR)_aX4-_a , wherein R is aliphatic or aromatic hydrocarbon group with carbon number 1 - 14 or COR' (wherein R' is aliphatic or aromatic hydrocarbon group with carbon number of 1 - 14), X is Cl, Br or I, and " a^" is 0, 1 , 2, 3 or 4.

11. The method according to Claim 10, wherein said silicon compound is silicon alkoxide.

12. The method according to any of Claims 1 to 6, wherein said titanium compound has general formula of Ti(OR⁴)_aX_b, wherein R⁴ is aliphatic or aromatic hydrocarbon group with carbon number of 1 - 14 or COR^D(wherein R° is aliphatic or aromatic hydrocarbon group with carbon number of 1- 14), X is Cl, Br or I, and " a" is an integer between 0-3, and b between 1 -4, and a+ b is 3 or 4.

13. The method according to Claim 12, wherein said titanium compound is titanium alkoxychloride or titanium chloride.

14. The method according to any of the Claims 1 to 13, wherein said carrier is additionally treated with organic aluminum compound with the molar ratio of Al/Ti = 0.1-2.0 before or after being treated with titanium compound.

15. The method according to any of the Claims 1 to 14, wherein said catalyst has the molar ratio of Ti/Mg = 0.01-2.0.

16. An ethylene polymerization or copolymerization method, wherein the method is performed using the catalyst produced by the method according to any of the Claims 1 to 15 and organic aluminum compound as cocatalyst.

17. The method according to Claim 16, wherein the organic aluminum compound is alkyl aluminum compound of AlR_nX₃-_n, wherein R stands for alkyl radical with carbon number of 1- 12, X for hydrogen atom or halogen atom such as Cl or F, or alkoxy radical with carbon number of 1- 12, and "n" for an integer or fraction thereof between 1-3.

18. The method according to Claim 17, wherein the organic aluminum compound is trimethyl aluminum, triethyl aluminum, or trioctyl aluminum.