JPS6181408A - Method of polymerizing propylene - Google Patents

Abstract

PURPOSE:To obtain the titled polymer efficiently without causing reduction in heat removal ability, by using a catalyst consisting of a solid transition metalcatalyst, an organoaluminum compund, and an improver for steric regularity, adding the improver for steric regularity to the vapor introduction part of a reflux condenser, and carrying out bulk polymerization. CONSTITUTION:In subjecting propylene to bulk polymerization by the polymerizer 1 using propylene itself as a medium by the use of a catalyst consisting of a solid transition metal catalyst, an organoaluminum compound and an improver for steric regularity, propylene vapor evaporated from the polymerizer 1 through the vapor introduction line 8 is blended with at least part of the improver fior steric regularity fed from the feed line 9 of the improver for steric regularity, fed to the reflux condenser 2, the propylene vapor is condensed, circulated from the circulation line 5 for the condensed solution to the polymerizer 1, so that the reaction heat is removed and the bulk polymerization of propylene is carried out at a constant temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for the polymerization of propylene. Specifically, the present invention relates to a method of polymerizing propylene at a constant temperature by removing the reaction heat with a reflux condenser using a bulk method using propylene itself as a medium.

Conventional technology It is known to remove the polymerization heat generated during a polymerization reaction through the wall of the reactor or by installing a heat exchanger inside the reactor, but in a large reactor, the heat transfer area is too large for the above method. Since it cannot be made large, a method using a reflux condenser that utilizes the latent heat of the liquid medium is used. (For example, equity 4
3-14226. Although the method using a reflux condenser has excellent heat removal ability, it has the problem that the monomer polymerizes in the reflux condenser, reducing the heat removal ability. Method of flowing active liquid (JP-A-48-88186) Method of spraying liquid (JP-A-51-88186)
84887. JP-A-52-96687) It has been proposed that a method using a specific shape (JP-A-49-18187) prevents the reduction in heat removal ability due to the adhesion of the polymer.

Problems to be Solved by the Invention The above-mentioned methods do not have a certain improvement effect in batch polymerization such as vinyl chloride polymerization for reducing the heat removal ability of the reflux condenser due to polymer adhesion. However, since the polymerization of olefins such as propylene is carried out by a continuous polymerization method, the above method is insufficient, and if the operation is continued for a long period of time, the heat removal capacity of the reflux condenser decreases, and the operation is interrupted and reflux cooling is performed. It was necessary to maintain the equipment.

The inventors of the present invention have conducted intensive studies on methods for solving the above-mentioned problems, and have found that the above-mentioned problems can be solved by performing specific operations, and have completed the present invention.

An object of the present invention is to provide a method for polymerizing propylene by removing reaction heat using a reflux condenser without causing a decrease in the heat removal ability of the reflux condenser.

A means for solving the problem, that is, the present invention, is to evaporate propylene using a bulk polymerization method using propylene itself as a medium using a catalyst consisting of a solid transition metal catalyst, an organoaluminum compound, and a stereoregularity improver, followed by reflux cooling. In the method of polymerizing propylene at a constant temperature by condensing propylene vapor in a vessel to remove the reaction heat,
A process for the polymerization of propylene, characterized in that at least 1 part of a stereoregularity improver is added to the introduction of the steam to a reflux condenser.

In the present invention, the polymerization of propylene includes not only propylene alone but also copolymerization of propylene with other olefins such as ethylene, butene-11-hexene-1, and as is clear from the structure of the invention, even if it is a multistage polymerization. good.

Although the method of the present invention is applicable to batch polymerization, it is particularly effective when applied to continuous polymerization. There are no particular limitations, and any catalyst system may be used as long as it is composed of the three components mentioned above.

Typical solid transition metal catalysts include titanium trichloride obtained by reducing titanium tetrachloride with a reducing agent such as metallic aluminum, organoaluminium, or organomatium, or titanium trichloride obtained by pulverizing them and treating them with a saccharifying agent such as ether. activated by further washing with an inert hydrocarbon, or further treatment with titanium tetrachloride, etc. Alternatively, titanium halide is supported on a carrier obtained by granulating halogenated magnesium silica, alumina, magnesium oxide, etc. by various methods such as pulverization, co-pulverization, dissolution precipitation, and spray drying, or as required. Examples include those that have been subjected to contact treatment with an oxygen-containing compound. Examples of organoaluminum compounds include trialkylaluminum such as triethylaluminum, tripropylaluminum tributylaluminum, trihexylaluminum or mixtures thereof, diethylaluminum chloride, dipropylaluminum chloride, cyphthylaluminum chloride, diethylaluminum chloride, or chlorine thereof. Examples include dialkylaluminum halogens such as those in which is substituted with bromine or iodine, or mixtures thereof, alkylaluminum sesquihalides, alkylaluminum cibarides, and among these, trialkylaluminum and dialkylaluminum halides are preferably used.

In the present invention, the stereoregularity improver refers to a compound used to improve the stereoregularity of the obtained polypropylene, and specifically includes oxygen-containing compounds, nitrogen-containing compounds, and sulfur-containing compounds, among which oxygen-containing compounds are used. Preferably used. Specifically, esters, ethers, amides, and alkoxy silicon compounds are preferably used, and aromatic carboxylic acid esters, dialkyl ethers, diaryl ethers, and alkoxy silicon compounds give particularly good results. Regarding the proportion used, the appropriate range varies depending on the compound used, but the ratio of organic aluminum to stereoregularity improver is usually 100 to 1.
('(l ratio) The weight ratio of organoaluminum to transition metal catalyst is 100-1 weight ratio.

In the present invention, the polymerization temperature is usually 30 to 90°C and 40°C because an inexpensive coolant can be used.
Preferably it is carried out at ~90°C.

Since propylene itself is used as a liquid medium, the polymerization pressure is determined by the quantitative ratio of propylene to other olefins, hydrogen used as a molecular weight regulator, or an inert medium such as flaxin.

Embodiments of the present invention will be described using the drawings.

(2) is a polymerization tank, in which the heat of reaction is removed by a heat exchanger 10 and a reflux condenser 2, and polymerization is carried out at a constant temperature. In the drawing, the temperature of the reaction tank is detected and a controller 11 is installed according to the temperature.
Although an example is shown in which the flow rate of the refrigerant introduced into the reflux condenser 2 is controlled by the following, there is no restriction at all as to various measures for controlling the polymerization temperature. Steam is supplied to the reflux condenser 2 through a line 8, and the reflux condenser is composed of, for example, a multi-tubular heat exchanger. It is circulated from the Rhinore to the polymerization tank via the blower 6.

A portion of the stereoregularity improver to be charged to the reaction vessel is introduced into line 8. At this time, 1 to be charged into the reaction tank
It is more effective to dilute the stereoregularity improver with 50% propylene and introduce it.

Transition metal catalyst Q, 3k, in which titanium tetrachloride was supported on heptanoium chloride in a 40 m3 reaction vessel according to the method of the present invention.
vh, h'J x chill aluminum O, ssg,
/h.

Diethylaluminum chloride 1.4 #/h 1 Methyl p-toluate 0.4 l as stereoregularity improver
/h and tetraexid run 0.41/h and charged 3
．． Polypropylene was polymerized at 75° at 2 T/h. The first liter Q, 271/h was diluted with 50 kl/h of propylene and charged, and the next 7
After 14 days of operation in which the reflux condenser (including pipes 5 and 7.8) was dismantled and examined, almost no deposits were found.

14 in the same manner without adding stereoregularity improver.
Daily operation (propylene was charged from line 9)
When the reactor was dismantled and examined, it was found that a small amount of polymer had adhered to the line 8, and a portion of the multi-tubular heat exchanger of the reflux condenser 2 was blocked.

Effect Stereoregularity improvers show the effect of reducing polymerization activity,
Especially when the ratio of the amount to other ingredients is large, the effect is significant. Therefore, by introducing a stereoregularity improver into the introduction line of the steam to the reflux condenser, a portion of it will flow back through the introduction line and enter the reaction tank, and a portion will accompany the steam to the reflux condenser and condensate. It is presumed that since the gas enters the reaction tank through the circulation line and the non-condensed gas circulation line, polymerization around the reflux condenser is not substantially caused.

Effects By carrying out the method of the present invention, it is possible to efficiently remove the reaction heat using a reflux condenser and continuously polymerize probylene, which is industrially valuable.

[Brief explanation of drawings]

The drawing shows an example of an apparatus for carrying out the method of the invention. 1 is a polymerization tank, 2 is a reflux condenser, 3 is a refrigerant introduction line/, 4
5 is the refrigerant discharge line, 5 is the condensate circulation line 6 is the blower
17 is a non-condensable waste circulation line, 8 is a steam introduction line, 9
is the stereoregularity improver introduction line, ] 0 is the stereoregularity improver introduction line, 1 is the stereoregularity improver introduction line,
1 is a converter, and 12 is a valve.

Claims (1)

[Claims] 1) Propylene is evaporated by a bulk polymerization method using propylene itself as a medium using a catalyst consisting of a solid transition metal catalyst, an organoaluminum compound, and a stereoregularity improver, and propylene vapor is produced in a reflux condenser. A method for polymerizing propylene at a constant temperature by condensing to remove the heat of reaction, characterized in that at least one part of a stereoregularity improver is added to the introduction of steam to a reflux condenser. 2) The method according to claim 1, wherein the stereoregularity improver is an oxygen-containing organic compound.