JPS617307A - Method of heterogeneous polymerization of olefin - Google Patents

Abstract

PURPOSE:To prepare stably a polyolefin while preventing adhesion of low-molecular-weight polymer, etc. produced as by-products, etc. to a container wall, by subjecting an olefin to heterogeneous polymerization in the presence of a fluorocarbon compound and a catalyst in a solvent. CONSTITUTION:0.01-5wt% fluorinated carbon compound such as monochlorodifluoromethane, etc. is added to a solvent such as propane, etc., and ethylene, propylene, butene-1, etc. is polymerized alone or copolymerized in the presence of Ziegler catalyst, Phillips catalyst, etc., to give the aimed polymer. EFFECT:Effective for polymerizing a copolymer such as a low-density polymer, soft polymer, etc. that forms easily a low-molecular-weight component. For example, a polyethylene having 0.90-0.94g/cm<3> density, a polypropylene having 4- 8wt% ethylene content, etc. are obtained in high productivity.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to the so-called slurry polymerization method in which olefins are heterogeneously polymerized in a solvent in the presence of a catalyst. The present invention relates to a method for stably producing polyolefins.

[Problem that the invention seeks to solve]

As a method for producing polyolefins by polymerizing or copolymerizing olefins, so-called slurry polymerization, in which polymerization is carried out by suspending a solid catalyst in a solvent, is generally employed.

However, in the case of this slurry polymerization, the low molecular weight polymers produced as by-products in the polymerization reaction are easily dissolved in the solvent and adhere to the walls of the polymerization vessel, which reduces the heat transfer coefficient and makes long-term continuous stable operation difficult. is normal.

In particular, when producing low-density copolymers by copolymerization with other olefins, the above-mentioned adhesion to vessel walls and a decrease in the heat transfer coefficient are likely to occur, making long-term stable operation impossible. , significantly reducing productivity.

One way to prevent such polymer adhesion to the vessel wall is to keep the slurry concentration low.

This is not preferable because it reduces productivity. Furthermore, many methods have been proposed in which the catalyst is preheated with a small amount of olefin, but these methods are not always satisfactory.

[Means for solving problems]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have discovered that when olefins are polymerized by slurry polymerization, a fluorocarbon compound is present in the polymerization system. The inventors have discovered that the adhesion of the polymer to the vessel wall can be prevented, and have arrived at the present invention.

That is, the gist of the present invention is a method for producing an olefin polymer by heterogeneously polymerizing an olefin in a solvent in the presence of a catalyst, which is characterized in that a fluorocarbon compound is present in the polymerization system. It depends on the polymerization method.

Furthermore, to explain the present invention in detail, the present invention is particularly effective for copolymers in which low molecular weight components are easily produced, and is suitable for the production of low-density polymers and soft polymers, which were difficult to produce in the past. The invention makes it easy to implement.

For example, polyethylene with a density of 0.90 to 0.9'lll/crti, polypropylene with an ethylene content of 1 to 4 g, etc. can be manufactured without reducing productivity.

The olefins used in the present invention include ethylene, phlopylene, butene-11pentene-11hexene-/,
Octene-/, 9-methylpentene-113-methylbutene-/, and the like. The above olefins can be homopolymerized or copolymerized by mixing them.

Further, as the polymerization solvent, a hydrocarbon solvent commonly used in slurry polymerization is used. Specifically, aliphatic hydrocarbon solvents such as propane, isophane, normal butane, normal pentane, normal hexane, normal octane, etc., alicyclic hydrocarbon solvents such as cyclopenkune, cyclohexane, etc., or aromatic hydrocarbons ,t
For example, benzene, toluene, xylene, etc. may be used alone or in combination of λ or more. It's a trench, propylene, butene.
Olefins such as 11-hexene-/ can also be used as solvents.

As the polymerization catalyst, a known catalyst for olefin polymerization is used. For example, so-called Ziegler catalysts consisting of transition metal compounds of groups 11 to 6 of the periodic table such as titanium, vanadine, and zircon and organometallic compounds of groups 1 to 3 of the periodic table, titanium trichloride or trichloride. So-called Ziegler-Natsuta catalysts whose main components are titanium/metal halogenide eutectic and organoaluminum compounds, other so-called Phillips catalysts (chromium oxide supported on silica, alumina, etc.), standard type catalysts 1 (r-Flumina, etc.) A typical example is molybdenum oxide (supported by molybdenum oxide).

The polymerization reaction is usually carried out at a temperature ranging from room temperature to I00'Q, and at a polymerization pressure ranging from normal pressure to /θθ atmospheric pressure.

The fluorocarbon compounds used in the present invention include compounds in which all or a part of the hydrogen atoms in the molecule of a hydrocarbon derivative are substituted with F (peru and polyfluoro compounds, or partially fluoro compounds), chlorofluorocarbons, bromocarbons, etc. Examples include fluorocarbons.

Specifically, they include monochlorodifluoromethane, trichloromonofluoromethane, dichlorodifluoromethane, monochlorotrifluoromethane, tetrachlorodifluoroethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, monopromotrifluoromethane, dibromotetrafluoroethane, and the like.

The amount of the above-mentioned fluorocarbon compound added is 0.0/-,4% by weight, preferably 0.0/-, 4% by weight, based on the solvent in the polymerization reactor.
．． 0.3-/wt%. If the amount added is too small, the effect of preventing the polymer from adhering to the container wall will be insufficient, and if the amount added is too large, the polymerization activity will decrease, which is not preferable.

The method of addition is not particularly limited, but it may be added to the solvent in advance or added during polymerization.

〔Example〕

Next, the present invention will be explained in detail by examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

In addition, in the following examples, the polymerization activity of the catalyst is K=
(,9 polymer)/(I solid catalyst)・(hr)・(k1
9/CI! olefin pressure).

Melt index (M engineering) is a value measured at 790° C. with a load of λ/1 kfl based on J Engineering SK-4760, and the unit is 9710 minutes. Further, the density (g/cc) was measured based on J Engineering 5KA7/, (7).

The measurement of the soluble components in normal hexane was carried out by extracting the polymer powder with boiling normal hexane for 2 hours using a Soxhlet extractor.

Example-(Preparation of Al catalyst component Magnesium jetoxide//, 31. Tree n-
Butoxymonochlorotitanium/3θI and n-butanol 37I were mixed at 730°C for an hour to homogenize. Next, lower the temperature in a 60℃ trench and add normal hexane a, q.
Added s z.

Next, qsqg of ethylaluminum sesquichloride was added dropwise, and stirring was continued at 60°C for 1 hour. By washing the generated precipitate with n-hexane, the brown catalyst component 2
1 og was obtained. A part of the obtained solid was dried and powdered, and analysis showed that 5MI was 70.0% by weight and T1 was q
, g weight was engaged.

fBl Polymerization of ethylene (using the solid catalyst component obtained in At)
Continuous polymerization of ethylene-butene-7 copolymerization was carried out using a n-hexane solvent at a liquid level of 30011 in a jacketed polymerization tank that was turned on.

The above solid catalyst component was introduced into the polymerization tank at a rate of 2 Vhr,
Diethylaluminium chloride x, , 7 g/hr,
N normal hexane 7 kg/hr, )
! J Chlorotrifluoroethane (Co, dtF-00
7Ft) 73 i/hr.

Ethylene, 2 j kVhr, butene-/5 k
g/hr, hydrogen 5 f! Continuous polymerization was carried out for 20 days at a polymerization temperature of 60° C. and a total pressure of g kg/ff1-G% and an average residence time of λ hours.

The average polymerization activity during this period was λ700 (i-polymer/saw catalyst/hr/ethylene pressure), and the MI of the obtained polymer was 8s<yyi.

min), and the density was 5.2% by weight for the boiling normal hexane extraction valve.

Heat removal by jacket water flow is extremely stable, and the overall heat transfer coefficient (Uo) of the heat transfer surface immediately after the start of polymerization, ? K
O (Kca shift 7 (・hr-deg), the overall heat transfer coefficient (Uf) immediately before the end of polymerization ke 330 (Kcall/
m'・hr-deg], the rate of decline during that period ('
"/1yo) was 0..3947 days after completion of the operation. When the reactor was opened and inspected after the completion of the operation, almost no adhesion was observed on the walls of the reactor.

Comparative Example-1 Ethylene-butene-1 was copolymerized in exactly the same manner as in Example-7 except that trifluoroethane was not supplied.

The polymerization activity during operation is 3θSθ (g polymer/g catalyst・hr・ethylene pressure), and the MI of the product is /1.2 (
1//10 cylinder), density is 0. The wa 11.0 (I/d) normal hexane extraction valve was S, S weight %.

In addition, the decrease in the overall heat transfer coefficient of the polymerization tank is due to the overall heat transfer coefficient (UO) of the heat transfer surface immediately after the start of polymerization of 4 J O (Kcad/
m′°hr°dθB), but it decreased rapidly during operation, and lθday/f J 00 (Kcall/m″・
hr-deg), and the polymerization was finally stopped. Average rate of decline during this period (/-Uf/Uo)Id, 2°/1
．． It was qV day.

After the reaction was completed, the reactor was opened and inspected, and wax-like deposits were found on the entire wall of the reactor.

Based on these results, it was determined that long-term operation would be difficult.

〔Effect of the invention〕

According to the method of the present invention, adhesion of the polymer to the vessel wall is prevented.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - Others/names Procedural formalities (spontaneous) November 73, 1982

Claims (1)

[Claims] (1) A method for heterogeneously polymerizing olefins to produce an olefin polymer by heterogeneously polymerizing olefins in a solvent in the presence of a catalyst, characterized in that a fluorocarbon compound is present in the polymerization system.