Preparation Method Of Catalyst For Ethylene Polymerization

Abstract

Disclosed is a method for preparing a solid catalyst capable of controlling a molecular weight distribution and polydispersity according to an organic compound as used in a polymerization reaction, in which the solid catalyst contains titanium tetrachloride and a diester or diether organic compound. The catalyst having excellent polymerization activity, and allowing uniform particle size and high apparent density of the ultra-high molecular weight polyethylene, and easily controlling the molecular weight distribution and polydispersity of the ultra-high molecular weight polyethylene may be prepared simply and efficiently.

Claims

1. A preparation method of a catalyst for producing ultra-high molecular weight polyethylene, the method comprising: (1) reacting magnesium dichloride (MgCl.sub.2) with alcohol to prepare a magnesium compound solution; (2) reacting titanium tetrachloride with the magnesium compound solution prepared in the step (1) to prepare a precursor; and (3) reacting the precursor with the titanium tetrachloride to form a first reacted precursor, and then secondarily reacting the first reacted precursor with a diether compound represented by a following general formula (I) or a diester compound represented by a following general formula (II) or a mixture of the diether compound and the diester compound to prepare the catalyst:
R.sub.1OCR.sub.2COR.sub.3  (I)
R.sub.1OOCR.sub.2COOR.sub.3  (II) where each of R.sub.1 and R.sub.3 represents a linear or branched alkyl group having 1 to 10 carbon atoms, and R.sub.2 represents a linear or branched alkyl group having 1 to 20 carbon atoms.

2. The method of claim 1, wherein the alcohol is a primary alcohol having 2 to 10 carbon atoms.

Description

DETAILED DESCRIPTION

[0023] The present disclosure will be described in more detail based on following Examples. However, these Examples are for illustrative purposes only, and the present disclosure is not limited to these Examples.

EXAMPLES

Example 1

[0024] [Preparation of Solid Catalyst for Preparation of Ultra-high Molecular Weight Polyethylene]

[0025] Step (1): Preparation of Magnesium Halide Alcohol Adduct Solution

[0026] After replacing an atmosphere of a 1 L reactor equipped with a mechanical stirrer with a nitrogen atmosphere, 20 g of solid magnesium dichloride (MgCl.sub.2), 120 ml of toluene, and 60 ml of normal butanol were added to the reactor and stirred at 350 rpm. After raising a temperature to 65° C. for 1 hour, the reactor was maintained for 2 hours to obtain a uniform magnesium halide alcohol adduct solution that was well dissolved in a solvent.

[0027] Step (2): Preparation of Magnesium Halide Carrier

[0028] After cooling the temperature of the solution prepared in step (1) to 20° C., 20 ml of TiCl.sub.4 was slowly injected thereto for 40 minutes (0.5 ml/min). Then, 62.5 ml of TiCl4 was injected thereto more rapidly for 100 minutes (0.625 ml/min). At this time, the temperature was carefully maintained so that the temperature of the reactor did not rise 25° C. or higher. When the injection was completed, the temperature of the reactor was raised to 60° C. for 1 hour and was further maintained for 1 additional hour. When all processes were completed, the reactor was allowed to stand and a solid component was completely settled and then a supernatant was removed, and then the solid component in the reactor was washed and precipitated once with 300 ml of toluene to completely remove liquid impurities. Thus, a clean magnesium chloride carrier was obtained as a solid.

[0029] Step (3): Preparation of Catalyst Carrying Titanium and 2-isopropyl-2-(1-methylbutyl)-1,3 -dimethoxypropane

[0030] 200 ml of toluene was added to the magnesium chloride carrier, and the mixture was maintained 25° C. while stirring the mixture at 250 rpm. Then, 27 ml of TiCl.sub.4 was injected thereto at a time and the mixture was maintained for 1 hour to perform a first reaction. After injecting 36.2 mmol of 2-isopropyl-2-(1-methylbutyl)-1,3-dimethoxypropane thereto, the reactor temperature was raised to 60° C. and the reactor was maintained for 1 hour to perform a second reaction between TiCl.sub.4 and the carrier. Then, the reactor was allowed to stand to completely settle the solid component and then a supernatant was removed. The prepared solid catalyst was washed and precipitated once with 200 ml of toluene and 6 times with 200 ml of hexane to remove impurities.

[0031] [Ultra-high Molecular Weight Polyethylene Polymerization]

[0032] A nitrogen atmosphere was created in a 2-liter batch reactor by alternately injecting nitrogen and vacuum three times into the 2-liter batch reactor. After 1000 ml of hexane was injected into the reactor, 1 mmol of triethylaluminum and 0.005 mmol of the solid catalyst based on a titanium atom were injected into the reactor. After 9 psi of hydrogen was injected thereto, a temperature of the reactor was raised to 80° C. while stirring the mixture therein at 700 rpm. Then, an ethylene pressure was adjusted to 120 psig, followed by slurry polymerization for 90 minutes. After the polymerization was completed, a temperature of the reactor was lowered to room temperature. Hexane slurry containing a resulting polymer was filtered and dried to obtain a white powdery polymer.

[0033] The polymerization activity (kg-PE/g-catalyst) was calculated as a weight ratio of the polymer as produced per an amount of the catalyst as used.

[0034] The particle size distribution of the polymer was measured using a laser particle analyzer (Mastersizer X, Malvern Instruments). As a result, the average particle size thereof was D (v, 0.5), and the particle size distribution thereof was expressed as (D (v, 0.9)−D (v, 0.1))/D (v, 0.5), where D (v, 0.5) represents a median size of particles contained in the sample, and D (v, 0.9) and D (v, 0.1) mean a particle size at 90% and 10% locations based on the size distribution, respectively. The smaller the number of particle size distributions, the narrower the particle size distribution.

[0035] M.sub.w (weight average molecular weight) and M.sub.n (number average molecular weight) and polydispersity (Polydispersity Index, PDI, Mw/Mn) of the polymer were measured and analyzed by gel permeation chromatography.

[0036] The polymerization results are shown in Table 1 together with the apparent density (g/ml) of the polymer.

Example 2

[0037] Example 2 was performed in the same manner as in Example 1, except that 2-isopropyl-2-(1-methylbutyl)-1,3-dimethoxypropane in Example 1 was changed to 36.2 mmol of diethyl succinate.

Example 3

[0038] Example 3 was performed in the same manner as in Example 1, except that 2-isopropyl-2-(1-methylbutyl)-1,3-dimethoxypropane in Example 1 was changed to 36.2 mmol of diethyl malonate.

Comparative Example 1

[0039] Comparative Example 1 was performed in the same manner as in Example 1, except that 2-isopropyl-2-(1-methylbutyl)-1,3-dimethoxypropane in Example 1 was not used.

TABLE-US-00001 TABLE 1 Titanium Average content Activity Apparent Molecular Poly- particle Particle in catalyst (kg-PE/g- density weight (M.sub.w) dispersity size size Examples (weight %) catalyst) (g/ml) (10.sup.6g/mol) (PDI) (μm) distribution Example 1 2.8 29.4 0.41 5.7 3.1 142 0.63 Example 2 3.1 26.5 0.42 5.9 5.1 131 0.79 Example 3 2.7 27.5 0.41 5.6 4.7 133 0.80 Comparative 7.5 13.2 0.33 5.3 3.8 240 1.3 Example 1

[0040] As shown in Table 1, it may be seen that the catalyst prepared by the methods of Examples 1 to 3 has excellent polymerization activity and allows a uniform particle size distribution and high apparent density of the polymer, compared to the catalyst prepared by the method of Comparative Example 1. Further, the polydispersity of the molecular weight distribution may be selectively adjusted according to the type of the organic compound as used.

[0041] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.