JPS6181409A - Method of controlling molecular weight - Google Patents

Abstract

PURPOSE:To control molecular weight of polypropylene in good controllability without losing hydrogen and propylene, by using propylene itself as a liquid medium, plymerizing propylene by a reaction tank provided with a reflux condenser. CONSTITUTION:In bulk polymerization method using propylene itself as a liquid medium, hydrogen is used as a molecular weight modifier, propylene is polymerized at a fixed temperature while evaporating propylene by at least part of polymerization heat, condensing and removing propylene vapor by the reflux condenser 2. At the beginning of the polymerization, an amount of hydrogen to be fed to the reaction tank 1 is controlled by an amount of polymerization calculated from calorific value and a previously obtained relationship between moleclar weight of polypropylene and hydrogen consumption, to control molecular weight of polypropylene.

Description

[Detailed description of the invention] A major invention in the field of industrial application (I am fascinated by the method of polymerizing propylene.Details:
i. It relates to a method for controlling the molecular weight of polypropylene obtained by using hydrogen in a loading and unloading process to incorporate propylene itself.

It is well known that when propylene is polymerized using the conventional Ziegler-Natsuta catalyst, the molecular weight of polypropylene that is broken can be controlled by the amount of hydrogen added during the polymerization (for example, J. Polymer Sci., C21).
09 (1974)) There is a certain relationship between the hydrogen concentration in the gas phase and the molecular weight of the polypropylene obtained (for example, J, P
olymer Sci,, Part At vo182
717 (1970)), polypropylene is usually produced by controlling the gas phase hydrogen concentration (1) to a constant value so that the polypropylene molecule (1) has a desired value.

On the other hand, when producing polypropylene using a large reactor, the heat of polymerization is removed simply through the wall of the warping machine or by installing a heat exchanger inside the reactor. Because of the difficulty, it is also known to remove the liquid medium using a reflux condenser that utilizes heat.

Problems to be Solved by the Invention 1 However, the above-mentioned reactor equipped with a reflux condenser cannot be used (・
When propylene is polymerized, the 1-flow cold bristles [ ] vessel is drained, (UIL 7) above (-4 so ・“1
5: Let's talk; In order to make a sound, the hydrogen gas in the gas phase should be constant for each gas phase (by introducing the hydrogen gas and /2
If you use the method of ejecting one, you will have to sequentially introduce and eject C hydrogen, so the amount of hydrogen and seven molecules that will be accompanied during evacuation will be approximately 5 large. It was small.

The inventors of the present invention have considered tax considerations regarding methods to solve the above problem, and have found that two methods have been adopted to solve the above problem: Hydrogen and/or
Alternatively, they discovered that it is possible to increase the molecular weight of polypropyleno by 1 ffllit without losing fS of propyleno, and completed the present invention.

The object of the present invention is to provide a method for producing polypropylene of reduced molecular weight without loss of raw material.

In order to solve this problem, the present invention is a bulk polymerization method in which propylene itself is used as a liquid ring, and hydrogen is used as a molecular weight regulator. The flow cooler condenses and removes the propylene gas at a constant rate of quality. In the method of polymerization,
The resulting polymerization process is predetermined:
1 molecular weight of propylene and hydrogen consumption, which is characterized by 1 lilj of molecular weight and 1 (goods) in accordance with the hydrogen consumption group in l response determined by the formula of 1 month of hydrogen consumption. .

The uninvented process is effective when propylene is polymerized using reaction 1 using propylene itself as a liquid medium and equipped with a reflux condenser.

This is because in a reaction tank that does not use a reflux condenser, the gas phase and liquid A
Since the gas is in vapor-liquid equilibrium and the gas phase is almost uniform, if you collect the gas in the gas phase and measure the hydrogen concentration in step 1-, you can accurately determine the hydrogen concentration in the gas phase. Therefore, it is possible to control the molecular weight of the polypropylene obtained by comparing the detected hydrogen concentration with the desired hydrogen 0 degree using a comparison means and introducing the insufficient hydrogen into the reaction tank by operating the hydrogen introduction valve. This is because it is a concave Noh play.

Uninventively, the polymerization of propylene is not only the homopolymerization of propylene, but also propylene and ethylene, butene-1,
Also includes polymerization with hexene-1 and the like.

In the present invention, a catalyst system consisting of a known transition metal catalyst and an organometallic compound (combined with a stereoregularity improver) is used, and there are no particular limitations. As a transition metal catalyst, titanium trichloride obtained by preparing titanium tetrachloride with a base material such as aluminum, organoaluminium, or organic magnesium, or titanium trichloride (τ6 crushed, treated with an oxygen-containing organic compound, Examples include titanium tetrachloride '2! which has undergone activation treatment such as IL processing, or titanium trichloride/or tetrasalt f hitita/ supported on a carrier such as magunium chloride, and organic 141 Examples of compounds include organoaluminiums such as trialkylaluminum, alkylaluminum halides, alkylaluminum heptasmohalides, and alkylaluminum cybarides, and organic maguniums such as dialkylmaguniums.

The aspects of the invention will be explained below with reference to the drawings.

11+ of production for carrying out the method of the present invention using Figure 1
il is shown. l is the reaction i・shi of rJ stirring 1st base,
2: Reflux condenser 3: Majike 7 4-1 is a gas flow rate and temperature detector 4-2 is a condensate flow rate and temperature detector 4-3 is a hydrogen gas introduction flow rate control valve , 4-
4 is a detector for the discharge amount and temperature of the cooling (or heating) water of the keenoto, and 4-5 is the cooling (or heating) of the keenoto.
Line 5 is the slurry introduction line (in the case of the first row, it is the catalyst slurry charging line) Line 6 is the slurry discharge line /, 7
indicates the propylene and catalyst charging line. 4-1 above
．． 21-2, 1-4.4 The signals a, b, c, and d detected at 5 are input to the data processor 8G, and are
The amount of polymerization is calculated from the calorific value by correcting the amount of heat, etc. On the other hand, the ratio between the amount of hydrogen consumed and the molecular weight of the obtained polypropylene (in Figure 2, the scale t of the molecular weight is expressed in degrees) is determined in advance to correspond to the desired molecular weight. By determining the amount of hydrogen consumed per unit weight of polypropylene, and introducing hydrogen corresponding to the product of polymerization - : , determined above, polypropylene having a constant molecular weight can be produced.

Continuous polymerization multi-tank with 1 connection port and polymerization machine with 5 medium cylinders and 6 cylinders
When polymerizing by changing the molecular weight with the beak, it goes without saying that it is necessary to correct the amount of hydrogen that enters and exits with the slurry.

At the start of polymerization, just introduce enough hydrogen to match the amount consumed: Since it is not possible to obtain a product with a certain molecular weight, the I volume of hydrogen relative to propylene is 111 rF%,
The required amount of hydrogen, taking into account the volume of the gas phase, is charged all at once, the molecular weight of the obtained polypropylene is measured, and after slight correction, the desired molecular weight is reached, and then hydrogen is introduced in an amount commensurate with the amount consumed as described above. It becomes possible to produce polypropylene with a certain molecular weight.

Effect: According to the present invention, the amount of hydrogen consumed when giving a constant molecular weight is -
Must be constant per peak weight. The concentration of hydrogen in the gas phase varies depending on the load on the flow cooling unit, and the apparent value fluctuates greatly, but on average, the equilibrium between the gas and liquid phases is maintained, and hydrogen is introduced in proportion to consumption. It can be assumed that the molecular weight could be maintained at a constant level by the two steps.

EXAMPLE A reaction was carried out using a reactor with an internal volume of -40 m' having the structure shown in Figure 1, using liquid propylene as a substance, and using a catalyst consisting of titanium trichloride and diethylaluminum chloride.
Polymerization was carried out at ゛C. At the beginning of the polymerization f4r, K 35 Nm of hydrogen was introduced in bulk so that the limiting viscosity 1 variable was 1.7), and after the initial modification, the iξ was calculated by For polymerization, 1. Polymerization was carried out sideways so as to introduce hydrogen at the core. Figure 3 shows the values obtained by monitoring the gas phase hydrogen concentration by sampling gas in the gas phase from line 9 in Figure 1. The graph shows the relationship between the intrinsic viscosity and the lt number of polypropylene (average 2,4 T/hour).While the hydrogen and nitrate values in the gas phase fluctuate, the intrinsic viscosity number remains constant.

Effects of the Invention By carrying out the method of the present invention, polypropylene of a constant molecular weight can be obtained efficiently and with good controllability, which is of great industrial significance.

[Brief explanation of the drawing]

Figure 1 is an example of electrical installation for carrying out the '75 white of the present invention, and Figure 2 is an example of the relationship between hydrogen consumption and intrinsic viscosity (polymerization sequence at constant temperature) No. 3r21 7.V) shows the relationship between the time course of the example and the intrinsic viscosity of the polypropylene obtained after cooling and cooling. Patent applicant Mitsui Tooh Chemical Co., Ltd. 17 ＾bcz ・ ・λ kart , = ka

Claims (1)

[Claims] A bulk polymerization method in which propylene itself is used as a liquid medium, hydrogen is used as a molecular weight regulator, and at least a portion of the polymerization heat is used to evaporate propylene and condense and remove the propylene vapor in a reflux condenser, while polymerizing propylene at a constant temperature. In a method of A method for controlling molecular weight characterized by: