KR100389961B1 - α-olefin prepolymerization method - Google Patents

Abstract

The present invention is a method for prepolymerizing an alpha olefin in the presence of (a) a magnesium-supported solid complex titanium catalyst and (b) an organometallic compound of a Group I or Group III metal of the periodic table, the molecular weight being at least 300 g / mol and viscosity It is related with the prepolymerization method of alpha olefin which uses this high inert solvent as a reaction medium.

Description

Prepolymerization Method of Alphaolefin {α-olefin Prepolymerization Method}

The present invention is a method for prepolymerizing an alpha olefin in the presence of (a) a magnesium-supported solid complex titanium catalyst and (b) an organometallic compound of a Group I or Group III metal of the periodic table, the molecular weight being at least 300 g / mol and viscosity It is related with the prepolymerization method of alpha olefin which uses this high inert solvent as a reaction medium.

In particular, the present invention is a prepolymerization method for quantitatively and uniformly injecting large-diameter prepolymers, and in the polymerization of polyethylene and polypropylene, which are prepolymerized and injected into a slurry, the prepolymer particle size is 100 microns. As a result of the large diameter, it is useful as a countermeasure for the case of causing concentration unevenness due to precipitation in the slurry or clogging due to the characteristics of a small amount of high pressure pump when injected into a small scale reactor of a pilot scale.

Conventional alpha olefin prepolymerization is performed by prepolymerization at room temperature using a low molecular weight (100 g / mol or less) and low viscosity inert liquid solvent such as hexane and heptane, followed by further dilution to slurry state in a storage drum. Was injected into the reactor. In this process, in the case of large diameter (over 100 microns) prepolymer, the concentration of the storage drum was changed over time due to precipitation in the storage drum. In addition, the commercial metering pump used to inject a small amount of the prepolymer into the pilot scale small reactor, causing frequent injection failure due to the problem that can not be injected into large diameter catalyst more than 100 microns.

The present invention has been made to solve the above problems, and an object of the present invention is to carry out the prepolymerization of alpha olefins in a reaction medium having a high molecular weight of 300 g / mol or more, such as mineral oil, high viscosity, It is to provide a pre-polymerization method of alpha olefin that can solve the injection failure and improve the reaction uniformity.

1 is a view showing the injection uniformity and the reactor temperature change according to the prepolymerization method according to an embodiment of the present invention.

The prepolymerization method of the alpha olefin of the present invention is a method of prepolymerizing an alpha olefin in the presence of (a) a magnesium-supported solid complex titanium catalyst and (b) an organometallic compound of a group I or group III metal of the periodic table. An inert solvent of 300 g / mol or more and high viscosity is used as a reaction medium. As the reaction medium, mineral oil is particularly preferred.

The magnesium-supported solid complex titanium catalyst (a) used in the present invention is U.S. Pat. Conventional Ziegler-Natta catalysts described in 4,946,816, 4,866,022, 5,013,702, 5,124,297, 4,330,649, European Patent No. 131,832, or Japanese Patent Laid-Open No. 63-54004 can be used.

Preferred examples of the magnesium-supported solid complex titanium catalyst (a) used in the present invention include (i) a non-reducible magnesium compound such as magnesium halide and a group IIIA compound of the periodic table of cyclic ether, at least one alcohol, phosphorus compound and organosilane. Dissolving in a mixed solvent to prepare a solution containing magnesium, (ii) reacting the magnesium compound solution with a transition metal compound, a silicon compound, a tin compound or a mixture thereof to precipitate solid particles, and (iii) The solid particles are reacted with a titanium compound and an electron donor, and then washed with a hydrocarbon solvent to obtain a solid catalyst particle whose particle shape is controlled.

The organometallic compounds (b) used in the present invention are specifically trialkylaluminum such as triethylaluminum or tributylaluminum, trialkenylaluminum such as triisoprenylaluminum, partially alkoxylated alkylaluminum such as di Dialkyl aluminum alkoxides such as ethyl aluminum ethoxide or dibutyl aluminum butoxide, alkyl aluminum sesquihalides such as ethyl aluminum sesquiethoxide or butyl aluminum sesquiethoxide, ethyl aluminum dichloride, propyl aluminum dichloride or Alkyl aluminum dihalide such as butyl aluminum dibromide, partially halogenated aluminum, for example aluminum hydride such as diethyl aluminum hydride or dibutyl aluminum hydride, dialkyl aluminum hydride such as dibutyl aluminum hydride Ethyl aluminum, and the at least one compound selected from ethoxy chloride, butyl aluminum butoxy chloride, ethyl aluminum, or the group consisting of partially alkoxylated and halogenated alkylaluminum such as ethoxy bromide, especially preferred is trialkylaluminum.

Generally, when the prepolymerization is carried out in a liquid phase, a relatively low viscosity inert solvent such as hexane, heptane or kerosene is used as the reaction medium. In the present invention, an inert solvent having a molecular weight of 300 g / mol or more and a relatively high viscosity is used. Used as a reaction medium, it is possible to suppress the phenomenon of prepolymer precipitation after completion of the prepolymerization reaction. As for the viscosity range of the fluorinated solvent used by this invention, 50-100 cst (centistox) is preferable at 40 degreeC.

In addition, when injecting into the polymerization reactor, grease is added at an appropriate ratio to uniformly mix so that prepolymer precipitation does not occur even after long-term storage, and uniformly mixed mixture with high viscosity is suitable for high viscosity fluid. By uniformly injecting into the reactor using a pump, it is possible to solve the poor injection and improve the reaction uniformity, and the prepolymers can be uniformly dispersed without precipitation.

In the case of liquid phase polymerization according to the present invention, the preferred proportion of the solid complex titanium catalyst (a) is about 5 to 500 millimoles of titanium atoms, preferably about 10 to 100 millimoles, preferably 1 liter of inert solvent. In the organometallic compound (b) component, the ratio of organometallic, especially aluminum atoms, is about 0.1 to 100 moles, preferably about 0.5 to 50 moles per mole of titanium atoms in the catalyst (a). .

The prepolymerization method of the alpha olefin of the present invention proceeds in the same manner as the prepolymerization method of the olefin using a conventional Ziegler-type catalyst. In particular, this reaction is carried out substantially in the absence of oxygen and water. The prepolymerization conditions of alpha olefins having a molecular weight of 300 g / mol or more and a highly viscous inert solvent as the reaction medium are sufficiently considered in consideration of the liquid viscosity and the solubility of the alpha olefins in the reaction medium during the prepolymerization. Should be selected, the preferred prepolymerization temperature is about 10 to 100 ℃, more preferably about 30 to 80 ℃ is suitable. The reaction pressure is from atmospheric pressure to 50 atm or less, preferably at a pressure of about 0.1 to 10 atm. The prepolymerization time is determined depending on the target prepolymerization, the activity of the catalyst, the solubility of the alphaolefin, and the like, and the preferred time is about 30 minutes to 5 hours.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these.

Example 1

Before starting the prepolymerization, the flask was filled with oil to remove moisture contained in the mineral oil to be used, and heated and stirred at 100 ° C. in a nitrogen atmosphere for at least 12 hours. A 4 liter reactor equipped with a mechanical stirrer and a cooling / heating jacket was prepared in a nitrogen atmosphere, and 1300 ml of mineral oil, a titanium catalyst, 100 g, and 150 mmol of triethylaluminum were sequentially injected. The reaction temperature was raised to 40 ° C. while stirring at a stirring speed of 350 rpm. After stirring for about 30 minutes, propylene injection was started. Prepolymerization was carried out while injecting propylene at a flow rate of 2 g / min for 2.5 hours while maintaining the reaction temperature at 40 ° C.

Example 2

Settling degree was compared for the following three kinds of slurry.

Sample 1: Oil slurry prepolymer + grease (oil / grease = 2/1 weight ratio) prepared in Example 1

Sample 2: Oil slurry prepolymer + grease (oil / grease = 3/1 weight ratio) prepared in Example 1

Sample 3 (Comparative Example): Hexane (HEXANE) slurry prepolymer

(1) The prepolymerization degree of the prepolymer for the above three samples was 3 [G-PP / G-catalyst], and the concentration was 20% by weight.

(2) The above three samples were filled to a height of 100 mm in a 7 cm diameter glass bottle with uniform stirring.

(3) After mixing the bottles containing the slurry sample uniformly, the mixture was left in a 0 ° C. constant temperature bath to measure the depth of precipitation with time.

Table 1. Comparison of Settling Depth with Time by Solvent Type (Unit: mm)

Neglect time Sample 1 (Example) Sample 2 (Examples) Sample 3 (Comparative Example) 1 minute 0 0 60 5 minutes 0 0 75 1 day 0 0 80 5 days One 1.5 80

As shown in Table 1, when the oil prepolymer and the grease were mixed, almost no sedimentation occurred until 5 days, while the hexane slurry prepolymer was mostly precipitated within 5 minutes.

Example 3

Pilot scale continuous polypropylene polymerization of prepolymer and hexane slurry prepolymer (comparative) prepared in the same composition as the oil prepolymer + grease mixture (oil / grease = 2/1 weight ratio) tested in Example 2 Injection stability in the reactor was compared.

<Polymerization Conditions and Procedures>

(1) 30 kg of liquid propylene was charged to a 150 Liter polymerization reactor equipped with a stirrer.

(2) The reaction temperature was 67 ° C., and hydrogen was injected so that the pressure was 30 kg / cm ² .

(3) The prepolymer injection amount is 1 g-titanium per hour, and the triethyl aluminum injection ratio is 4 g-aluminum / g-titanium and the Si-based electron donor is 3.5 g-Si / g-titanium. Each was injected continuously.

(4) The oil prepolymer + grease mixture was a piston type pump, and the hexane slurry prepolymer was injected using a reciprocating metering pump.

(5) The injection uniformity and the reactor temperature change according to the above two cases were measured and shown in FIG. 1.

As shown in FIG. 1, when the hexane slurry prepolymer was injected, the injection amount was not uniform, and the reaction temperature fluctuated severely, whereas the injection amount was uniform even when the oil prepolymer + grease was injected. The reaction temperature was also confirmed to be relatively uniform.

In conclusion, the phenomenon of prepolymer precipitation after the completion of the prepolymerization reaction was suppressed by the prepolymerization method according to the present invention, the injection failure was solved, and the reaction uniformity was improved.

As can be seen from the above, according to the prepolymerization method of the alpha olefin of the present invention, the uniformity of concentration and injection stability of the large diameter catalyst slurry of 100 microns or more in diameter is improved, thereby improving the polymerization stability of the polymerization reaction and the quality of the product. It has the effect of improving the uniformity.

Claims (5)

A method of prepolymerizing an alpha olefin in the presence of a catalyst comprising (a) a magnesium-supported solid complex titanium catalyst and (b) an organometallic compound of a group I or group III metal of the periodic table, the molecular weight being at least 300 g / mol The prepolymerization method of alpha olefin characterized by using a highly viscous inert solvent as a reaction medium. The method according to claim 1, wherein the inert solvent is a mineral oil. The prepolymerization method of alpha olefin according to claim 1, wherein the viscosity of the inert solvent is in the range of 50 to 100 centistokes at 40 ° C. The prepolymerization method of an alpha olefin according to any one of claims 1 to 3, wherein the organometallic compound is trialkyl aluminum. The ratio of the solid complex titanium catalyst (a) is 5 to 500 millimoles of titanium atoms per 1 liter of the inert solvent, and the ratio of the organic metal in the organometallic compound (b) component is A prepolymerization method for alpha olefins, characterized in that from 0.1 to 100 moles per mole of titanium atoms in the catalyst (a).