Preparation Method Of Catalyst For Ethylene Polymerization

Abstract

Disclosed is a method for preparing a titanium solid catalyst supported on magnesium dichloride that may be used to prepare ultra-high molecular weight polyethylene having a high apparent density. Performing a polymerization reaction using a solid catalyst containing titanium tetrachloride and a phthalate compound may allow ultra-high molecular weight polyethylene having uniform particle size and high apparent density to be prepared.

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 titanium tetrachloride and phthalate compound to prepare the catalyst.

2. The method of claim 1, wherein the alcohol is an alcohol having 4 to 20 carbon atoms.

3. The method of claim 1, wherein the phthalate compound includes at least one phthalate compound represented by a following general formula (I)
R.sub.1OOC(C.sub.6H.sub.4)COOR.sub.2   (I) where each of R.sub.1 and R.sub.2 represents an alkyl group of 1 to 10 carbon atoms.

Description

DETAILED DESCRIPTION

[0022] 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

[0023] [Preparation of Solid Catalyst for Preparation of Ultra-High Molecular Weight Polyethylene]

[0024] Step (1): Preparation of magnesium halide alcohol adduct solution

[0025] 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.

[0026] Step (2): Preparation of magnesium halide carrier

[0027] After cooling the temperature of the solution prepared in step (1) to 20° C., 20 ml of TiCl.sub.4 was slowly injected to thereto for 40 minutes (0.5 ml/min). Then, 62.5 ml of TiCl.sub.4 was injected thereto more rapidly for 100 minutes (0.625 ml/min). At this time, the temperature was maintained so that the temperature of the reactor did not rise 25° C. or higher carefully. When the injection was completed, the temperature of the reactor was raised to 60° C. for 1 hour and was maintained for 1 hour additionally. 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 to obtain a carrier.

[0028] Step (3): Preparation of catalyst carrying titanium and diisobutyl phthalate

[0029] 200 ml of toluene was added to the 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 diisobutyl phthalate 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. When all processes were completed, 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 six times with 200 ml of hexane to remove impurities.

[0030] [Ultra-High Molecular Weight Polyethylene Polymerization]

[0031] 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 1,000 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 to 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.

[0032] The polymerization activity (kg-PE/g-catalyst) was calculated as a weight of the polymer as produced per an amount of the catalyst as used. 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 the particle size exhibited by 50% of a sample, and D (v, 0.9) and D (v, 0.1) indicate the particle size exhibited by 90% and 10% of samples, respectively. The smaller the numerical value of the distribution, the narrower the distribution. The M.sub.w (weight average molecular weight) and the molecular weight distribution (M.sub.w/M.sub.n) of the polymer were measured and analyzed using gel permeation chromatography. The polymerization results are shown in Table 1 together with the apparent density (g/ml) of the polymer.

Example 2

[0033] Example 2 was conducted in the same manner as in Example 1, except that 36.2 mmol of dimethyl phthalate was used instead of diisobutyl phthalate in Example 1.

Example 3

[0034] Example 3 was carried out in the same manner as in Example 1, except that 36.2 mmol of diethyl phthalate was used instead of diisobutyl phthalate in Example 1.

Comparative Example 1

[0035] Comparative Example 1 was carried out in the same manner as in Example 1, except that 36.2 mmol of ethyl benzoate was used instead of diisobutyl phthalate in Example 1.

Comparative Example 2

[0036] Comparative Example 2 was carried out in the same manner as in Example 1, except that diisobutyl phthalate was not used in Example 1.

Comparative Example 3

[0037] Step (1): Preparation of magnesium halide alcohol adduct solution

[0038] 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, 20 ml of tetrahydrofuran, and 40 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.

[0039] Step (2): Preparation of magnesium halide carrier

[0040] After cooling the temperature of the solution prepared in step (1) to 20° C., 20 ml of TiCl.sub.4 was slowly injected to thereto for 40 minutes (0.5 ml/min). Then, 62.5 ml of TiCl.sub.4 was injected thereto more rapidly for 100 minutes (0.625 ml/min). At this time, the temperature was maintained so that the temperature of the reactor did not rise 25° C. or higher carefully. When the injection was completed, the temperature of the reactor was raised to 60° C. for 1 hour and was maintained for 1 hour additionally. When all processes were completed, the reactor was allowed to stand and a solid component was completely settled and then a supernatant is removed, and then the solid component in the reactor was washed and precipitated once with 300 ml of toluene to completely remove liquid impurities to obtain a carrier.

[0041] Step (3): Preparation of catalyst carrying titanium and diisobutyl phthalate

[0042] 200 ml of toluene was added to the 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 diisobutyl phthalate 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 six times with 200 ml of hexane to remove impurities.

[0043] [Ultra-High Molecular Weight Polyethylene Polymerization]

[0044] 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 1,000 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 to 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.

[0045] The polymerization activity (kg-PE/g-catalyst) was calculated as a weight of the polymer as produced per an amount of the catalyst as used. 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 the particle size exhibited by 50% of a sample, and D (v, 0.9) and D (v, 0.1) indicate the particle size exhibited by 90% and 10% of samples, respectively. The smaller the numerical value of the distribution, the narrower the distribution. The M.sub.w (weight average molecular weight) and the molecular weight distribution (M.sub.w/M.sub.n) of the polymer were measured and analyzed using gel permeation chromatography. The polymerization results are shown in Table 1 together with the apparent density (g/ml) of the polymer.

TABLE-US-00001 TABLE 1 Titanium content Activity Molec- Par- in (kg- Ap- ular Average ticle catalyst PE/g- parent weight particle size (weight cata- density (10.sup.ng/ size distri- Examples %) lyst) (g/ml) mol) (μm) bution Example 1 2.8 28.5 0.45 5.6 131 0.60 Example 2 2.3 24.3 0.43 5.8 125 0.74 Example 3 2.6 26.2 0.43 5.6 127 0.76 Comparative 3.6 15.7 0.39 5.5 112 0.70 Example 1 Comparative 7.5 10.8 0.33 5.3 240 1.3 Example 2 Comparative 2.9 19.4 0.37 6.2 193 1.1 Example 3

[0046] As shown in Table 1, the catalyst prepared by the methods of Examples 1 to 3 may allow production of the ultra-high molecular weight polyethylene with uniform particle size and very high apparent density at excellent polymerization activity.

[0047] 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.