KR100279498B1 - Method for preparing polyisobutene using transition metal compound-methylaluminoxane catalyst system - Google Patents

Abstract

The present invention utilizes a transition metal compound or an organic compound containing a tertiary halogen atom as a main catalyst, and methylisoluminene as a cocatalyst to use polyisobutene having a high molecular weight such as methyl chloride at a higher reaction temperature. The present invention relates to a method for preparing a non-polar solvent using a general organic solvent such as toluene as a polymerization solvent, and specifically, isobutene is dissolved in a polymerization solvent such as toluene, followed by transition metal compounds such as titanium or tertiary halogen. Adding an organic compound having atoms activated with methylaluminoxane to react at -50 to -10 캜 for 30 to 360 minutes; Adding a methanol solution to the reaction solution to terminate the reaction; The precipitated polymer is washed several times with methanol and then filtered and dried to obtain a final polymer. The polyisobutene obtained through such a process has a weight average molecular weight of about 300,000 to 1,000,000.

Description

Method for preparing polyisobutene using transition metal compound-methylaluminoxane catalyst system

The present invention relates to a method for producing polyisobutene using a transition metal compound-methylaluminoxane catalyst system. More specifically, the main catalyst is a transition metal compound in which a chlorine atom or an alkoxy group is substituted for a transition metal such as titanium, vanadium, or tin. The present invention relates to a method for producing polyisobutene in high yield at a reaction temperature that is higher than that of the prior art by using methylaluminoxane prepared as alkyl aluminum and a small amount of water as a promoter.

Polymerization of the polyisobutene by cationic polymerization method is known to be a polymer of a high molecular weight at a very low temperature below -80 ℃ by the polymerization activity species of carbocations quite unstable form, as catalyst, mainly AlCl _3, BCl _3, etc. Strong Lewis acid was used, and methyl chloride as a polar solvent was used alone or mixed with dichloromethane as a polymerization solvent.

However, this polymerization method is excessively expensive in the polymerization process because the polymerization is carried out at cryogenic temperatures, and the excessive use of the catalyst is accompanied by difficulty in removing the catalyst, and the polymerization solvent also uses a solvent containing chlorine which is harmful to the environment. There was a problem.

On the other hand, an example of polymerizing isobutene with a catalyst in which a transition metal compound is mixed with alkylaluminum or aluminum halide has been tried before.

As a specific example, US Pat. No. 4,107,417 has prepared a polyisobutene having a weight average molecular weight of about 200,000 at -40 ° C using a Group 4 transition metal compound and an alkylaluminum as a catalyst. As the solvent, chlorinated solvents such as monochloromethane and dichloromethane were used.

Recently, a polymerization method without using alkylaluminum and methyl chloride has also been disclosed. Specifically, trispentafluoroboron is used as a cocatalyst, and toluene is used as a polymerization solvent. A method for preparing polyisobutene is described (see US Pat. No. 5,448,001). According to the publication published by Timothy et al. ("Journal of Polymer Science: Part A: Polymer Chemistry", 35, 329-344 (1997)), various experiments on isobutene polymerization using this promoter were carried out at -20 ° C. A polymer having a number average molecular weight of about 140,000 was obtained with a polymerization yield of 60% at the polymerization temperature.

In addition, many studies on the cationic polymerization characteristics of various titanium compounds have been reported. Tomacyuki et al. ("Macromolecules", 29, 6100-6103 (1996)) disclose that titanium triions may be used for cationic polymerization of styrene. It has been reported that chloroisopropoxide (TiCl ₃ (OiPr)) acts alone as a Lewis acid catalyst without a promoter. However, this titanium catalyst acted as a polymerization catalyst alone in the polymerization of styrene, but in the case of isobutene polymerization, it did not function as a polymerization catalyst without the aid of a cocatalyst.

On the other hand, as a non-coordinating anion for activating the transition metal compound catalyst, research on methylaluminoxane in addition to the alkyl aluminum and trispentafluoroboron has recently been of interest.

Methylaluminoxane is a compound produced by reacting alkylaluminum with a small amount of water. It is known that methylaluminoxane has an excellent function in terms of polymerization activity until now as a cocatalyst of metallocene catalyst.

The present invention is a catalyst system in which a catalyst having a large volume encapsulates an active site of a main catalyst by using a transition metal compound and an organic compound containing a tertiary halogen atom as a main catalyst and a methylaluminoxane having a high molecular weight as a promoter. It is an object of the present invention to provide a method for preparing polyisobutene, which allows more stable cationic active species to be produced.

In addition, the present invention uses a general organic solvent such as toluene instead of dichloromethane, which is a polar solvent, at a polymerization temperature of about 30 to 50 ° C. higher than that of the conventional polymerization process, thereby reducing process cost and reducing polyisobutene. It is also an object to provide a method of manufacturing.

Method for producing a polyisobutene of the present invention for achieving the above object comprises the steps of dissolving isobutene in a polymerization solvent containing no halogen atoms; Apart from this, a catalyst system is prepared by activating a transition metal compound represented by Chemical Formula 1 or an organic compound represented by Chemical Formula 2 with methylaluminoxane represented by Chemical Formula 3 for a predetermined time; A polymerization step of reacting the activated catalyst system with the isobutene solution for 30 to 360 minutes at -50 to -10 ° C; Methanol is added to the reaction solution to terminate the reaction; And washing the precipitated polymer several times with methanol, followed by filtration and drying to obtain the final polymer.

Wherein M is titanium, vanadium or tin,

X is a chlorine atom or bromine atom,

n is an integer of 1 to 4,

R is selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, octyl, pentyl and perfluorophenyl groups.

R ₁ , R ₂ and R ₃ are the same as or different from each other, an alkyl group having 1 to 10 carbon atoms or a phenyl group,

X is as above.

Wherein m is an integer of 3 to 40.

The present invention will be described in more detail as follows.

The present invention relates to a method for preparing a high molecular weight polyisobutene at a higher temperature than in a conventional industrial production process using a transition metal compound main catalyst and a methylaluminoxane cocatalyst.

Looking specifically at the method for producing a polyisobutene of the present invention, isobutene is first injected into the polymerization solvent.

In the present invention, as the polymerization solvent does not use a solvent containing a halogen atom as in the prior art, the polymerization solvent that can be used in the present invention is a single or mixed solution selected from toluene, cyclohexane and hexane.

When the catalyst system is added to the reactor in which the isobutene solution is present, the catalyst system of the present invention is represented by the transition metal compound represented by the formula (1) or the organic compound represented by the formula (2) and the cocatalyst (3) It is obtained by dissolving the methylaluminoxane to be dissolved in a small amount of a polymerization solvent and aging for a certain time.

Such a catalyst system is added to the reactor and reacted for 30 to 360 minutes at the polymerization temperature of -50 to -10 ° C to prepare polyisobutene.

If the polymerization temperature is higher than the above range, there is a problem that the polymerization yield and the molecular weight of the polymerization product is reduced, and if the polymerization time is out of the above range, a low molecular weight polymer is produced and the molecular weight distribution value of the polymerization product is increased.

At this time, the concentration of the polymerization catalyst is preferably 1/500 to 1/1000 based on the weight of the isobutene monomer, and the concentration of the cocatalyst is preferably 1/100 to 1/250. If the concentration of the polymerization catalyst and the concentration of the cocatalyst are out of the above range, there is a problem that the polymerization yield falls.

Preferred promoter concentrations are those that are 1-10 times the concentration of the main catalyst.

Termination of the polymerization reaction is carried out by dropping a cold methanol solution into the reaction solution to remove the remaining catalyst. A methanol solution is added dropwise to the reaction solution to precipitate the polymer. The precipitated polymer is washed with methanol and then filtered and dried to obtain the final polymer.

As described above, when the polyisobutene is polymerized using the transition metal catalyst and the methylaluminoxane cocatalyst, the yield is 40 to 100% and the polyisobutene can be polymerized in a high yield.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

All reagents used in the experiments were stored under nitrogen atmosphere after purification. The reaction was tested three times over time. The inside of the reactor of 100 ml was depressurized for 2 hours and then sufficiently substituted with argon gas.

After injecting 20 mL of purified toluene and 5.64 g (100 mmol) of isobutene through the alumina column, the temperature was lowered to -20 ° C.

Separately, 0.10 mL (0.9 mmol) of titanium (IV) chloride and 0.08 mL (0.3 mmol) of titanium (IV) isopropoxide were reacted in dichloromethane for 2 hours, and then 1.84 mL of methylaluminoxane was used as a promoter. 0.48 mmol) was mixed. It was cooled to -20 ° C.

The catalyst was added to a reactor and reacted at -20 ° C for 120 minutes.

The reaction was terminated by dropwise adding 1 ml of methanol solution to the reaction solution, wherein unreacted material was removed by stirring the reaction solution under air. The precipitated polymer was washed several times with methanol and then filtered and dried.

Examples 2 to 3

Polyisobutene polymerization was carried out in the same manner as in Example 1 except that 0.46 mL (0.12 mmol) and 0.92 mL (0.24 mmol) of methylaluminoxane were used.

Examples 4-6

Polyisobutene polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was -30 ° C, -40 ° C, and -50 ° C, respectively.

Example 7

Polyisobutene polymerization was carried out in the same manner as in Example 1, except that 0.013 ml (0.12 mmol) of titanium (IV) chloride was used as a catalyst.

Example 8

Polyisobutene polymerization was carried out in the same manner as in Example 1, except that 0.033 ml (0.12 mmol) of tin chloride was used as a catalyst.

Example 9

Polyisobutene polymerization was carried out in the same manner as in Example 1, except that 0.020 mL (0.12 mmol) of cumyl chloride was used as a catalyst.

Example 10

Polyisobutene polymerization was carried out in the same manner as in Example 1, except that 0.013 ml (0.12 mmol) of t-butyl chloride was used as a catalyst.

Comparative Examples 1 to 3

In Comparative Example, polyisobutene polymerization was carried out in the same manner as in Example 1, except that 0.054 ml (0.48 mmol) of ethyl aluminum dichloride was used as a promoter. In addition, it superposed | polymerized at -20, -50, -80 degreeC, respectively.

The result of polymerizing polyisobutene according to the above Examples and Comparative Examples is as shown in Table 1 below.

Yield (%) Number average molecular weight (Mn) Weight average molecular weight (Mw) Molecular Weight Distribution (Mw / Mn) Example One 67.5 157,000 325,000 2.08 2 32.5 125,000 318,000 2.54 3 10.8 103,000 242,000 2.35 4 72.0 237,000 494,000 2.09 5 85.2 296,000 637,000 2.15 6 89.5 379,000 960,000 2.53 7 94.5 71,000 156,000 2.20 8 100.0 17,000 96,000 5.65 9 32.0 74,000 145,000 1.96 10 46.0 91,000 178,000 1.95 Comparative example One 45.5 24,000 82,000 3.44 2 64.3 63,000 304,000 4.82 3 86.6 108,000 576,000 5.33

From the results of the above table, the amount of methylaluminoxane in the titanium trichloroisopropoxide-methylaluminoxane catalyst system according to the present invention was most effective when it was 1 to 4 times of the transition metal compound as the main catalyst, and the molecular weight was lowered as the polymerization temperature was lowered. It can be seen that this larger polymer is produced. On the other hand, when an organic compound having a tertiary halogen atom is used as the main catalyst (Examples 9 and 10), a high molecular weight polyisobutene is formed, but the conversion rate in Examples 7 and 8 in which the transition metal compound is used as the main catalyst is The effect was close to 100%. For example, when ethyl aluminum dichloride is used as a promoter (Comparative Examples 1, 2, 3), in order to obtain a molecular weight of about 200,000, the reaction temperature needs to be low to -80 ° C. As a result, when the transition metal compound catalyst and the large-volume methylaluminoxane cocatalyst were used as the catalyst system as in the present invention, when a low-molecular alkylaluminum chloride used as a cocatalyst was used (Comparative Examples 1 to 3). In addition to the effect of raising the polymerization temperature by about 30 to 50 ° C., it can be seen that polyisobutene having a relatively constant molecular weight is obtained in view of the narrow molecular weight distribution.

As described in detail above, when the polyisobutene is prepared using a transition metal compound or an organic compound containing a tertiary halogen atom as a main catalyst and methylaluminoxane as a promoter according to the present invention, or While polyisobutene having similar physical properties can be obtained, the polymerization can be performed at a higher reaction temperature than in the prior art, thereby reducing the excessive process cost for maintaining cryogenic temperature, and without using a polar solvent such as methyl chloride, and general toluene. Since the organic solvent is used as the polymerization solvent, there is an effect to reduce the harmfulness.

Claims (3)

Dissolving isobutene in a polymerization solvent containing no halogen atoms; Apart from this, a catalyst system is prepared by activating a transition metal compound represented by Chemical Formula 1 or an organic compound represented by Chemical Formula 2 with methylaluminoxane represented by Chemical Formula 3 for a predetermined time; A polymerization process of adding the activated catalyst system to the isobutene solution and reacting at -50 to -10 ° C for 30 to 360 minutes; Methanol is added to the reaction solution to terminate the reaction; And a method of preparing polyisobutene using a transition metal compound-methylaluminoxane catalyst system, wherein the precipitated polymer is washed several times with methanol and then filtered and dried to obtain a final polymer. Formula 1 Wherein M is titanium, vanadium or tin, X is a chlorine atom or bromine atom, n is an integer of 1 to 4, R is selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, octyl, pentyl and perfluorophenyl groups. Formula 2 R ₁ , R ₂ and R ₃ are the same as or different from each other, an alkyl group having 1 to 10 carbon atoms or a phenyl group, X is as above. Formula 3 Wherein m is an integer of 3 to 40. The method of claim 1, wherein the main catalyst represented by the formula (1) is 1/500 to 1 / 2,000 concentration with respect to the isobutene monomer, and the cocatalyst represented by the formula (2) is added at a concentration of 1 to 10 times the main catalyst Method for producing a polyisobutene using a transition metal compound-methyl aluminoxane catalyst system, characterized in that. The method for producing polyisobutene using a transition metal compound-methylaluminoxane catalyst system according to claim 1, wherein the polymerization solvent containing no halogen atoms is selected from toluene, cyclohexane and hexane and used alone or in combination. .