EP1360212A4

EP1360212A4 - A method for producing ethylene homo- and copolymer

Info

Publication number: EP1360212A4
Application number: EP01272946A
Authority: EP
Inventors: Sang-Yull Kim; Chun-Byung Yang; Ji-Yong Park; Weon Lee
Original assignee: Samsung General Chemicals Co Ltd
Current assignee: Hanwha General Chemicals Co Ltd
Priority date: 2000-12-29
Filing date: 2001-12-22
Publication date: 2004-09-15
Also published as: WO2002053607A1; EP1360212A1

Abstract

The present invention provides a method for producing ethylene homo-and copolymers, particularly comprising the steps of using a catalyst produced by the following method comprising reacting the phosphorus compound, silane compound and mixture solution dissolved in alcohols, then reacting the obtained solution with titanium compound again, and preactivating the obtained catalyst by reacting with organic magnesium compounds as main catalyst, and producing ethylene homo- and copolymers by adding a saturated hydrocarbon compounds containing halogen during polymerization. The present invention provides a method for producing ethylene homo- and copolymers with high yield, and having a bimodal molecular structure resulted from a high molecular tail, while maintaining their narrow molecular distribution.

Description

A METHOD FOR PRODUCING ETHYLENE HOMO- AND CO-POLYMER

Technical Field

The present invention relates to a method for preparing homopolymer and copolymer of ethylene, and more particularly, to a method for preparing homopolymer and copolymer of ethylene, by using a preactivated catalyst as a main catalyst and by introducing saturated hydrocarbon compound containing halogen during polymerization, the preactivated catalyst being prepared by reacting a magnesium solution dissolved in alcohol with phosphorus compound, silane compound and mixture of titanium compound and silicone compound in turn, and with titanium compound again, and then by preactivating the reacted solution through the reaction with organomagnesium compound.

Background of the Invention

A lot of processes and catalysts for polymerization and copolymerization have been developed and well known generally. In particular, the polymer and the copolymer, which have large average molecular weight while maintaining narrow molecular weight distribution, are in much demand for application to various fields of industry. The polymer and the copolymer having large average molecular weight and narrow molecular weight distribution have the merit of exhibiting good physical properties.

Magnesium containing catalysts for polymerization and copolymerization of ethylene are known to exhibit very high catalytic activity and are suitable for liquid phase or gas phase polymerization. To be used as a catalyst for liquid phase polymerization of ethylene, the catalyst should have high catalytic activity. In addition, molecular weight distribution is an important factor which determines the physical properties of ethylene polymers. Especially, narrow molecular weiglit distribution of the polyethylene is a very important and advantageous feature for the injection molding processed products. As the molecular weight of the polymer increases, tensile strength becomes high but processability is reduced so causing the problem of occurring split during processing. One method to solve this problem is to introduce high molecular weight tail to molecular weight distribution while raising molecular weight. Especially, the introduction of high molecular weight tail is ideal since it can increase tensile strength while not affecting the processability.

Disclosure of the Invention

The object of the present invention is to provide a method for preparing polymer and copolymer of ethylene which have narrow molecular weight distribution and show bidentate structure in the molecular weight distribution curve, by using the simple method which includes preactivating prepared catalyst and introducing saturated hydrocarbon containing halogen during polymerization. The method for producing homo- and co-polymers of ethylene according to the present invention comprises carrying out polymerization or copolymerization of ethylene in the presence of (1) a solid titanium complex catalyst prepared by the steps of (a) preparing a magnesium solution by contacting halogenated magnesium compound, which is a support, with alcohol, (b) reacting said magnesium solution with phosphorus compound and silane compound containing alkoxy group as electron donors, (c) preparing a catalyst precursor through recrystallization into solids by contacting the solution prepared in step (b) with solution of mixture of titanium compound and silicone compound, (d) preparing a solid titanium complex catalyst by reacting the catalyst precursor with titanium compound, and (e) preactivating the solid titanium complex catalyst by reacting with organomagnesiurn compound; (2) organometallic compound in Group U or HI of the Periodic Table; and (3) a saturated hydrocarbon containing halogen, which is introduced during polymerization.

For producing catalysts of the present invention, the types of halogenated magnesium compounds used include but are not limited to: dihalogenated magnesiums such as magnesium chloride, magnesium iodide, magnesium fluoride, and magnesium bromide; alkymagnesium halides such as methylmagnesium halide, ethylmagnesium halide, propylmagnesium halide, butylmagnesium halide, isobutylmagnesium halide, hexylmagnesium halide, and amylmagnesium halide; alkoxymagnesium halides such as methoxymagnesium halide, ethoxymagensium halide, isopropoxymagnesium halide, butoxymagnesium halide, octoxymagnesium halide; or aryloxymagnesium halides such as phenoxymagnesium halide and methyl-phenoxymagnesium halide. Above magnesium compounds can be used in the mixture of two or more of said compounds or in the form of a complex compound with other metals. The magnesium solution used in the present invention can be produced as solution by using the aforementioned halogenated magnesium compounds in the presence a hydrocarbon solvent or in the absence thereof, by using alcohol.

The hydrocarbon solvents used in the present invention include but are not limited to aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, and kerosene; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, and methylcyclohexane; or aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene, and cymene.

When a halogenated magnesium compound is converted into a magnesium solution, alcohol is used in the presence of the aforementioned hydrocarbons or in the absence thereof. The types of alcohol include but are not limited to those containing 1 ~ 20 carbon atoms, such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, decanol, dodecanol, octadecyl alcohol, benzyl alcohol, phenylethyl alcohol, isopropyl benzyl alcohol, and cumyl-alcohol, although alcohol containing 1 - 12 carbon atoms is preferable. The total amount of alcohol is preferably 2.0-10 mol per each mole of magnesium compounds, and the dissolving temperature, while depending on the types of alcohol, is about 0 ~ 150°C, and the dissolving time is about 15 minutes ~ 5 hours or preferably about 30 minutes ~ 4 hours.

The phosphoruos compound used in the present invention is expressed by the following general formula:

PX _aRVθR²)c or POX _dR³e(OR⁴)_f , where X is a halogen atom, and R¹, R², R³ or R⁴ is a hydrocarbon of an alkyl, alkenyl or aryl group, having 1 ~ 20 carbon atoms, each of which can be same or different from one another, with a + b + c = 3, 0 < a< 3 , 0≤b < 3 , 0≤c <3 , d + e + f = 3, 0< d≤3, 0≤e≤3, and 0≤f≤3. The type of these includes phosphorus trichloride, phosphorus tribromide, diethylchlorophosphite, diphenylchlorophosphite, diethylbromophosphite, diphenylbromophosphite, dimethylchlorophosphite, phenylchlorophosphite, trimethylphosphite, triethylphosphite, tri-n-butylphosphite, trioctylphosphite, tridecylphosphite, triphenylphosphite, triethylphosphate, tri-n-butylphosphate, or triphenylphophate. Other phosphorous compounds satisfying the aforementioned formula may be used. As for the amount used, 0.25 mole or less per 1 mole of magnesium compound, and more preferably 0.2 mole or less per 1 mole of magnesium compound, is appropriate.

The silane compound having an alkoxy group, another electron donor, is represented as the general formula: R_nSi(OR)₄__n. where R is a hydrocarbon group having 1~12 carbon atoms, and n natural number between 1 and 3. More specifically, the following compounds can be used: dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, methylphenylmethoxysilane, diphenylethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, ethylsilicate, butylsilicate, or methyltriaryloxysilane. As for the amount used, 0.05 ~ 3 moles per 1 mole of magnesium compound, or more preferably 0.1 ~ 2 moles, is preferable.

The titanium compounds used in the present invention is expressed by the following general formula:

Ti(OR)_aX₄-a where R stands for an alkyl group with 1—10 carbon atoms, X a halogen atom, and "a" is a natural number between 0 and 4. Examples of titanium compounds which satisfy the general formula of Ti(OR)_aX₄-_a include 4-halogenated titanium such as TiCl₄, TiBr₄, and Tilt; 3-halogenated allcoxy-titanium such as Ti(OCH₃)Cl₃, Ti(OC₂H₅)Cl₃, Ti(OC₂H₅)Br₃, and Ti(O(i-C₄H₉))Br ; 2-halogenated alkoxy-titanium such as Ti(OCH₃)₂Cl₂, Ti(OC₂H₅)₂Cl₂, Ti(O(i-C₄H₉))₂Cl₂ and Ti(OC₂H₅)₂Br₂; and tetra-alkoxy titanium such as Ti(OCH₃) , Ti(OC₂H₅)₄, and Ti(OC₄H₉) . A mixture of the above titanium compounds can also be used in the present invention. The preferable titanium compounds are those containing halogen, or more preferably titanium tetrachloride. The silicon compounds used in the present invention is expressed by the following general formula; R_nSiCl₄-_n where R stands for hydrogen; or an alkyl, alkoxy, haloalkyl, or aryl group having 1—10 carbons; or a halosilyl or halosilylalkyl group having 1~8 carbons; and n is a natural number between 0 and 3. Examples of silicon compounds satisfying the above general formula include silicon tetrachloride; trichlorosilane such as methyltrichlorosilane, ethyltiϊchlorosilane, phenyltrichlorosilane; dichlorosilane such as dimethyldichlorosilane, diethyldichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane; monochlorosilane such as trimethylchlorosilane; and a mixture of these silicon compounds can also be used in the present invention. The preferable compound is silicon tetrachloride.

The appropriate amount of the mixture of a titanium compound and a silicon compound used during recrystallization of the magnesium compound solution is 0.1 ~ 200 moles per 1 mole of magnesium compound and preferably 0.1 ~ 100 moles, more preferably 0.2 ~ 80 moles. The appropriate mole ratio of a titanium compound to a silicon compound in the mixture is 0.05 ~ 0.95 and more preferably 0.1 ~ 0.8. The reaction of a magnesium compound with the mixture of a titanium compound and a silicon compound should preferably be carried out at a sufficiently low temperature to crystallize particles of the catalyst since the shape and the size of the resultant re- crystallized solid components vary a great deal according to the reaction conditions and affect the bulk density of polymer. It is preferable that the reaction should be carried out by contacting at -70 ~ 70 ^°C , or more preferably at -50 ~ 50 ^°C . After the contact-reaction, the temperature is slowly raised and reaction is carried out for the duration of 0.5 ~ 5 hours at 50 - 150 ^°C .

The catalyst precursor prepared as above is further reacted with titanium compound represented by general formula Ti(OR)_aX₄._a , where R stands for a hydrocarbon group, X a halogen atom, and "a" is a natural number between 0 and 4. The most preferable compound is titanium tetrachloride and the amount is preferably 1~20 moles per 1 mole of magnesium compounds and more preferably 1-10 moles. Reaction is carried out for 0.5 -5 hours at 40 ^°C - 150 ^°C

The catalyst prepared as above is preactivated by reacting with organomagnesium compound represented by the general formula R_aMgX , where R stands for alkyl, alkenyl, cycloalkyl or alkynyl group having 1-10 carbons, X halogen, and "a" and "b" integers between 0 and 2 satisfying a + b=2, More specifically, examples of the organomagnesium compound are methylmagnesium chloride, methylmagnesium bromide, methylmagnesium iodide, ethylmagnesium chloride, ethylmagnesium bromide, propylmagnesium chloride, butylmagnesium chloride, pentylmagnesium bromide, hexylmagnesium bromide, octylmagnesium chloride, decylmagnesium bromide, dodecylmagnesium bromide, isopropylmagnesium chloride, isobutylmagnesium chloride, isobutylmagnesium bromide, tertiarybutylmagnesium chloride, cyclopentylmagnesium chloride, cyclopentylmagnesium bromide, cyclohexylmagnesium chloride, dibutylmagnesium, diethylmagnesium and dioctylmagnesium. Other compounds satisfying the above general formula can also be used. The amount of the organomagnesium compound used is preferably 0.02 - 1 mol per 1 mole of halogenated magnesium compound and more preferably 0.1 - 0.5 mol. When organomagnesium compound is used more than the amount of the present invention, the catalyst activity can be drastically reduced or the shape of catalyst can be destroyed, fn addition, since the shape of the catalyst changes with reacting temperature, the reaction should by carry out at sufficiently low temperature. Preferably, the reaction should be carried out at -50 ^°C - 50 ^°C or more preferably at -20 ^°C - 30 ^°C. After the contact-reaction, the temperature is slowly raised and the reaction is carried out for 0.5 -5 hours at 40 ^°C - 150 ^°C

The catalyst produced according to the process of the present invention can be utilized for homo- and co-polymerization of ethylene. As a comonomer, α-olefin such as propylene, 1-butene, 1-pentene, 4-methyl-l-pentene, or 1-hexene having three or more carbons can be used.

In the polymerization reaction for producing polymer and copolymer of ethylene according to the present invention uses, as a main catalyst, a titanium catalyst prepared as above and, as a cocatalyst, organometallic compounds of Group H or El of the Periodic Table.

The organometallic compound used as a cocatalyst of the present invention can be represented by a general formula of MR_n, .wherein M stands for a metal component of Group II or IHA in the Periodic Table such as magnesium, calcium, zinc, boron, aluminum or gallium, and R an alkyl group with 1 -20 carbons such as methyl, ethyl, butyl, hexyl, octyl or decyl group, and n the atomic valence of the metal component. Among these organometallic compounds, the trialkyl aluminums such as triethylaliiminum and triisobutylalurrώium, having an alkyl group of 1 - 6 carbons, or mixture of these are preferable. If needed, organoaluminum compound having one or more of halogen or hydride group, such as emylaluminum dichloride, (tiemylaluiriinum chloride, ethylaluminum sesquichloride, or dusobutylaluminum hydride, can be used.

The polymerization process can be gas phase polymerization or bulk polymerization which is carried without organic solvent, or the process can be liquid slurry polymerization which is carried with organic solvent, h the case of gas phase polymerization, the amount of the catalyst in the reaction system is, in terms of the titanium atom in catalyst, about 0.001 - 5 mmol, and preferably

0.001 - 1.0 mmol, and more preferably 0.01 - 0.5 mmol per one liter of the polymerization volume.

The concentration of the organometallic compound, as calculated by organometallic atom, is preferably 1 - 2,000 moles per 1 mole of titanium atoms in catalyst, and more preferably about 5 -

500 moles. In case of liquid phase slurry polymerization, nonpolar organic solvent of alkane compounds such as hexane, n-heptane, octane, nonan or decane, and aromatic compounds such as cycloalkane is used. Among this, hexane is most preferable and must be purified before use so as not to affect catalyst activity. The concentration of solid titanium complex catalyst in the polymerization reacting system is preferably about 0.001 - 5 mmol, in terms of titanium atoms in catalyst, per one liter of the solvent, and more preferably about 0.001 - 0.5 mmol.

It is essential to add saturated hydrocarbon containing halogen during polymerization to obtain polymers having molecular weight distribution in which high molecular weight tail is manifested. Saturated hydrocarbon such as ethylchloride, chloroform, t-butylchloride, tetrachloromethane, ethylbromide, t-butyliodide, n-butylbromide, n-butyliodide and n-butylfluoride, or their mixtures, which contains one or more of halogen of chlorine, bromine, fluorine and iodine, and has 1-10 carbons, can be used. Among these ethylchloride is most preferable. When saturated hydrocarbon containing halogen is injected with the mole ratio of 0.5-20 moles to titanium atoms in the catalyst and more preferably 2~10moles, best result can be obtained in catalyst activity and molecular weight distribution. In addition, by carrying out polymerization without saturated hydrocarbon containing halogen, polymers with reduced ratio of polymers having relatively high molecular weight can be obtained.

The appropriate temperature of polymerization is generally about 20 - 200 °C, and more preferably about 20 - 95 °C. The appropriate pressure of monomers is between 1 and 100 atm, and more preferably between 2 and 50 atm.

The molecular weight of polymers can be controlled by adjusting the amount of hydrogen injected, which is well known in the art. The molecular weight of the polymers is represented as melt index (ASTM D 1238), which is generally known in the art, and the value of the melt index generally becomes larger as the molecular weight decreases. The molecular weight distribution of polymers is measured with gel permeation chromatography (GPC), which is measured by commonly used method in the art.

Best Mode for Carrying out the Invention

The present invention will now be described with reference to the examples and comparative examples. These examples, however, are for the purpose of illustration only, and not intended to limit the invention.

Example 1 Preparation of catalyst

A solid titanium complex catalyst component is produced by following steps.

(a) Preparation of a magnesium compound solution Into a 1.0L reactor of nitrogen atmosphere equipped with a mechanical stirrer, 9.5 g of MgCl and 500 ml of decane are placed and after stirring at 500 rpm, 72 ml of 2-ethyl hexanol is added and reacted for 3 hours at temperature 120 °C. The homogenous solution obtained is cooled to room temperature.

(b) Contacting the magnesium solution with phosphorus compound and alkoxy silane compound To the magnesium compound solution cooled to room temperature, 7.4 ml of triethylphosphite and 15.0 ml of silicon tetraethoxide are added, and then reacted for an hour.

(c) Treating with solution of mixture of titanium compound and silicone compound To the solution prepared in step (b) adjusted to room temperature, a solution of mixture of 90 ml of titanium tetrachloride and 90 ml of silicon tetrachloride is dripped for 2 hours. After completing the dripping step, the temperature of the reactor is raised to 80° C for an hour and maintained at that temperature for an hour. After stirring, the supernatant of the solution is removed, and to the remaining solid layer, 300 ml of decane and 100 ml of titanium tetrachloride are added continuously. Then, the temperature is raised to 100°C and maintained thereat for two hours. After the reaction, the temperature is cooled to room temperature and is washed by injecting 400ml of heptane, (d) Reacting with titanium compound To the slurry prepared at step (c) 150ml of heptane and 150ml of titanium tetrachloride are injected in order. Then the temperature of the reactor is raised for two hours to 95 °C, and maintained thereat for 4 hours and then cooled to room temperature. After stopping the stirrer, it is washed by injecting 400ml of heptane until remaining free titaniumtetrachloride which is not reacted is removed. The quantity of titanium of the prepared solid catalyst is 5.0%.

Preactivation of catalyst

60ml of lmol dibutylmagnesium is dripped, for 1 hour, to reactor which contains the catalyst in slurry state and whose temperature is set to the temperature of 20 ° C. Stirring is performed for 5 hours while ma taining the temperature.

Polymerization

A 2L high-pressure reactor is dried in an oven and assembled while hot. In order to make the inside of the reactor nitrogen atmosphere, nitrogen and vacuum are alternatively manipulated three times in the reactor. Then 1,000 ml of dry n-hexane is injected to the reactor and 0.09 mmol of tnϊsobuthylaluminum and 0.09 mmol of ethylchloride are injected in order and the solid catalysts of 0.03 mmol in terms of titanium atom and 1000 ml of hydrogen are added thereto. The temperature of the reactor is raised to 80 ° C while stirring at 700 φm with a stirrer and the pressure of ethylene is adjusted to 80psi, and the polymerization is carried out for an hour. After the polymerization, the temperature of the reactor was lowered to room temperature, and an excessive amount of ethanol solution is added to tenninate the reaction. The polymer produced is collected segregatedly using filters and is dried in a vacuum oven at 50 ° C for at least six hours.

The polymerization activity (kg of polyethylene divided by mmol of Ti) is calculated as the weight (kg) ratio of the polymers produced per catalysts used (mmol of Ti). The results of polymerization are shown in Table 1, together with the melt index (g/10 minutes), molecular weight distribution (Mw/Mn), and the degree of manifestation of high molecular weight tail(Mz/Mw).

Example 2

120ml of 1 mole solution of dibutylmagnesium is added in the process of preactivating the catalyst in example 1, and the results of polymerization are shown in Table 1.

Example 3 60ml of 1 mole solution of diethylmagnesium is added instead of dibutylmagnesium in the process of preactivating the catalyst in example 1, and the results of polymerization are shown in Table 1.

Example 4 60ml of 1 mole solution of butylmagnesium chloride is added instead of dibutylmagnesium in the process of preactivating the catalyst in example 1, and the results of polymerization are shown in Table 1.

Example 5 The amount of ethyl chloride added is changed to 0.27mmol in the polymerization in example

1, and the results of polymerization are shown in Table 1.

Example 6

0.09mmol of chloroform is added instead of ethyl chloride in the polymerization in example 1, and the results are shown in Table 1.

Example 7

0.09mmol of tertiarybutyl chloride is added instead of ethyl chloride in the polymerization in example 1, and the results are shown in Table 1.

Example 8

0.09mmol of dichloroethanol is added instead of ethyl chloride in the polymerization in example 1 , and the results are shown in Table 1.

Example 9

0.09mmol of dichloromethanol is added instead of ethyl chloride in the polymerization in example 1 , and the results are shown in Table 1.

Example 10

0.09mmol of phenyle chloride is added instead of ethyl chloride in the polymerization in example 1, and the results are shown in Table 1.

Comparative example 1

The catalyst preactivation process in example 1 is omitted. The quantity of the titanium in the catalyst prepared is 5.0%. The polymerization is carried out in the same condition as that of example 1 except that ethyl chloride is not added, and the results are shown in Table 1.

Comparative example 2

The catalyst preactivation process in example 1 is omitted. The content of the titanium in the catalyst prepared is 5.0%. The polymerization is carried out in the same condition as that of example 1, and the results are shown in Table 1.

Comparative example 3

The polymerization is carried out using the catalyst prepared in example 1 without adding ethyl chloride and the results are shown in Table 1.

Table 1

Note

E: Example, CE: Comparative Example

Organomagnesium Bu₂Mg: dibutylmagnesium

At ane halide EC: e%1chlor.de, CHC1₃: chloroform, t-BuCl: tertiarybufyl chloride, DCE: dichloroethane, DCM: dichloromethane, PC: Phenyl chloride

As shown above, by using the preparation method of polymer and copolymer of ethylene according to the present invention, high molecular weight tail is manifested while mamtaining high activity of catalyst and narrow molecular weight distribution, making it possible to obtain polymer having bidentate molecular weight distribution. The polymer having narrow molecular weight distribution, and molecular weight distribution wherein high molecular weight tail is manifested exhibits excellent physical properties and can be usefully applied to injection processed products.

Claims

What is claimed is:

A method for preparing homopolymer and copolymer of ethylene, which is carried out in the presence of:

(1) a solid titanium complex catalyst prepared by the steps of

(a) preparing a magnesium solution by contacting halogenated magnesium compound with alcohol, (b) reacting said magnesium solution with phosphorus compound and silane compound having alkoxy group as electron donors,

(c) preparing a catalyst precursor by contacting the solution prepared in step (b) with solution of mixture of titanium compound and silicone compound,

(d) preparing the solid titanium complex catalyst by reacting the catalyst precursor with titanium compound, and

(e) preactivating said solid titanium complex catalyst by reacting the solid titanium complex catalys with organomagnesium compound;

(2) organometallic compound in Group II or HI of the Periodic Table; and

(3) a saturated hydrocarbon containing halogen, which is introduced during polymerization.

2. The method for preparing homopolymer and copolymer of ethylene according to claim

1, wherein said phosphorus compound is a compound expressed by following general formulas:

PX_aR¹b(OR²)_c, or POX_dR³ _e(OR⁴)_f, where X is a halogen atom, and each of R¹, R², R³ and R⁴ is an alkyl, alkenyl or aryl group, having 1 - 20 carbon atoms, each of which can be same or different from one another, with a + b + c = 3, 0<a<3 , 0 <b <3 , 0<c<3 , d + e + f = 3, 0 <d<3, 0 <e< 3, and

0≤f<3; and said silane compound having alkoxy group is a compound of a general formula of R_nSi(OR)₄-n, where R is a hydrocarbon group having 1-12 carbon atoms, and "n" is a natural number between 1 and 3.

3. The method for preparing homopolymer and copolymer of ethylene according to claim 2, wherein the said phosphorus compound is phosphorus trichloride, phosphorus tribromide, diethylchlorophosphite, diphenylchlorophosphite, diethylbromophosphite, diphenylbromophosphite, dimethylchlorophosphite, phenylchlorophosphite, trimethylphosphite, triethylphosphite, tri-n- butylphosphite, trioctylphosphite, tridecylphosphite, triphenylphosphite, triethylphosphate, tri-n- butylphosphate, or triphenylphophate; and silane compound having alkoxy group is dimethyldiiriethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, methylphenylmethoxysilane, diphenylethoxysilane, e yltrimethoxysilane, vmyltrimethoxysilane, memyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltrietl oxysilane, butyltriethoxysilane, phenyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, ethylsilicate, butylsilicate, or methyltriaryloxysilane.

4. The method for preparing homopolymer and copolymer of ethylene according to claim 1, wherein said titanium compound is represented by a general formula of Ti(OR)_aX₄-_a, where R is an alkyl group with 1—10 carbon atoms, X is a halogen atom, and "a" is a natural number between 0 and 4, and said silicon compound is represented by a general formula of R_nSiC -_n, where R stands for hydrogen; or an alkyl, alkoxy, haloalkyl, or aryl group having 1—10 carbons; or a halosilyl or halosilylalkyl group having 1-8 carbons; and " " is anatural number between 0 and 3.

5. The method for preparing homopolymer and copolymer of ethylene according to claim 4, wherein said titanium compound is a 4-halogenated titanium, which is selected from the group consisting of TiC , TiBr₄, and TU ; a 3-halogenated alkoxytitanium, which is selected from the group consisting of Ti(OCH₃)Cl₃, Ti(OC₂H₅)Cl₃, Ti(OC₂H₅)Br₃, and a 2- halogenated alkoxytitanium, which is selected from the group consisting of Ti(OCH )₂Cl , Ti(OC₂H₅)₂Cl₂, Ti(O(i-C-β₉))₂Cl₂, and Ti(OC₂H₅)₂Br₂; or a tetraalkoxytitanium, which is selected from the group consisting of Ti(OCH₃)₄, Ti(OC₂H₅)₄, and or mixture of these; and said silicon compound is silicon tetrachloride; a trichlorosilane, which is selected from the group consisting of methyltrichlorosilane, ethyltrichlorosilane, and phenyltrichlorosilane; a dichlorosilane, which is selected from the group consisting of dimethyldichlorosilane, diethyldichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane; or a monochlorosilane such as trimethylchlorosilane.

6. The method for preparing homopolymer and copolymer of ethylene according to claim 4, wherein said titanium compound is titanium tetrachloride, and said silicon compound is silicon tetrachloride.

7. The method for preparing homopolymer and copolymer of ethylene according to claim 1, wherein said organomagnesium compound, which is used in the preactivation of the catalyst, is represented by a general formula of R_aMgX , where R is an alkyl, alkenyl, cycloalkyl, or alkynyl having 1-10 carbons, and X is a halogen, "a" and "b" are integers between 0 and 2 and satisfying a+b=2.

8. The method for preparing homopolymer and copolymer of ethylene according to claim 7, wherein said organomagnesium compound is methylmagnesium chloride, methylmagnesium bromide, methylmagnesium iodide, ethylmagnesium chloride, ethylmagnesium bromide, propylmagnesium chloride, butylmagnesium chloride, pentylmagnesium bromide, hexylmagnesium bromide, octylmagnesium chloride, decylmagnesium bromide, dodecylmagnesium bromide, isopropylmagnesium chloride, isobutylmagnesium chloride, isobutylmagnesium bromide, tertiarybutylmagnesium chloride, cyclopentylmagnesium chloride, cyclopentylmagnesium bromide, cyclohexylmanesium chloride, dibutylmagnesium, diethylmagnesium or dioctylmagnesium.

9. The method for preparing homopolymer and copolymer of ethylene according to claim 1, wherein said saturated hydrocarbon which contains halogen is ethyl chloride, chloroform, tertiarybutyl chloride, tetrachloromethane, ethyl bromide, teriarybutyl iodide, n-butyl bromide, n- butyl iodide or n-butyl fluoride.