JPS5867704A - Purifying method of polypropylene and apparatus - Google Patents

Abstract

PURPOSE:To purify the titled polymer in a very simple apparatus, by washing a formed polymer with a washing liquid consisting of a monomer as a principal component at such a rising rate as to form an interface between a slurry and the washing liquid, and using partition plates of specific dimension in the vertical direction of a countercurrent washing column. CONSTITUTION:Propylene as a medium is solely mass polymerized or copolymerized with another alpha-olefin, and a slurry containing the resultant polypropylene is introduced from a nozzle 1 into a long countercurrent washing column having a part of <=250cm<2> cross-sectional area surrounded by partition plates in the vertical direction and >=10X(cross-sectional area surrounded by the partition plates)<1/2> length in the vertical direction. Propylene for washing is then introduced from a nozzle 3 to control the rising rate under such conditions as to form an interface between the slurry and the washing liquid. The slurry is then washed in the countercurrent manner to discharge the washing liquid from a discharging nozzle 2 and the slurry from a discharging nozzle 4 respectively. Thus, the formed polymer is washed and purified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for purifying polypropylene. Specifically, it was obtained by a bulk polymerization method using propylene itself as a medium. The present invention relates to a method and apparatus for efficiently washing polypropylene and providing polypropylene with excellent properties.

A method of obtaining polypropylene by polymerizing propylene by a bulk polymerization method using propylene itself as a medium is known, and the polypropylene obtained in this way contains residual catalyst and hazardous polypropylene, so it has a low ash content,
Since it is a low atactic polypropylene, it cannot be used in applications that require it. For this reason, various methods have been used to remove the catalyst residue and atactic polypropylene from the obtained polypropylene. As a method for removing the catalyst residue and the hazardous polypropylene, the polypropylene obtained by polymerization is treated with a suitable method using a countercurrent washing tower to solubilize the catalyst residue, or carbonization of propylene, etc. is carried out without any treatment. The method of purifying polypropylene by washing with hydrogen is an excellent method because it has advantages such as simple equipment and no need for special stirring means.

For example, an example of this can be seen in Japanese Patent Publication No. 47-42379. However, the method of purifying polypropylene using a countercurrent washing tower is extremely efficient when it is carried out using a countercurrent washing tower with a relatively small cross-sectional area, but it is difficult to process polypropylene polymers. Therefore, when the equipment is enlarged, the catalyst residue in the purified polypropylene taken out from the bottom of the countercurrent washing tower and the atactic polypropylene/
The amount of polypropylene increases, and the purification effect of polypropylene decreases.

The large difference in effectiveness between the large countercurrent cleaning tower and the small countercurrent cleaning tower is thought to be due to the following reasons. A countercurrent washing tower is originally introduced from the top, and the running washing solids are introduced from the bottom and washed or extracted by the round washing liquid by moving from the top to the bottom while contacting the washing liquid introduced from the bottom in a countercurrent, and the solids are washed or extracted by the washing liquid introduced from the bottom. In this device, the extracted solids come from the bottom, but if the device is made larger, the cleaning liquid from the bottom will not flow as a laminar flow. In other words, since turbulence tends to occur, the solids and liquids move downward, and as a result, the solids are discharged from the bottom together with the extraction liquid or cleaning liquid.
Solids are also discharged from the upper part along with the extraction liquid or washing liquid, resulting in a decrease in washing efficiency or extraction efficiency.

The inventors of the present invention have conducted various studies on ways to prevent the performance of the countercurrent cleaning tower from deteriorating due to the increase in the size of the equipment described above. The present invention was completed by discovering that it is possible to efficiently purify polypropylene even when the size of the polypropylene is increased.

That is, the present invention provides a cleaning solution containing propylene as a main component by using a countercurrent cleaning field to process polypropylene obtained by bulk polymerization using propylene itself as a medium, or by copolymerizing propylene with other α-olefins. In the method of purification by countercurrent cleaning using a countercurrent cleaning tower, a countercurrent cleaning tower with a longer partition plate in the vertical direction of the countercurrent cleaning tower is used to control the rising speed of the cleaning solution in two ways. This is a patented method and apparatus for purifying propylene, which is characterized by controlling the conditions such that the propylene is produced.

In the present invention, the polypropylene to be washed supplied to the countercurrent washing tower is produced by polymerizing propylene alone or propylene and other α-onfins using a bulk polymerization method using propylene itself as the entire medium. / is formed as a slurry.

The polymerization is carried out by a known method using a known stereoregular catalyst and is not particularly limited, but it is more preferable to use a relatively highly active catalyst to give polypropylene at a high yield per catalyst.

Further, in order to remove the residual catalyst more efficiently, it is more preferable to treat the residual catalyst with a compound that solubilizes the residual catalyst in a cleaning solvent mainly composed of propylene.

The slurry to be cleaned obtained as described above is introduced from the upper part of the countercurrent cleaning tower. Introducing the slurry from the top of the countercurrent cleaning tower The nozzle is inserted into the countercurrent cleaning tower from the top of the countercurrent cleaning tower, and a conical slurry dispersion cone is provided below the nozzle to wash the slurry in countercurrent. More preferred for uniform distribution throughout the column.

A partition plate is further provided in the counter-current washing tower in the vertical direction of the counter-current washing tower, and the partition plate is provided so that the cross-sectional area of the portion surrounded by the partition plate is 250 mm or less. It is an essential condition for achieving the present invention that the cross-sectional area of the portion surrounded by the partition plate is 250 cf1 or less; if it is 2502 or more, the effect of the present invention cannot be obtained, and the preferable range is 4 to 4 cm. 2
It is 50-. If it is less than 42, polypropylene tends to become clogged, which is not preferable.

It is more preferable that the partition plates are divided into two or more stages in the vertical direction, with appropriate intervals provided between each partition plate, to further disperse the slurry that has passed through the - partition plate. The cleaning liquid mainly consisting of propylene is introduced from the top, and the introduction nozzle for the cleaning liquid is preferably inserted into the bottom of the countercurrent cleaning tower, and it is preferable to use piping having a large number of holes.

Further, the introduction speed of the cleaning liquid must be set such that the L valve speed in the countercurrent cleaning tower creates an interface between the slurry and the cleaning liquid in the countercurrent cleaning tower.

Above this speed, polypropylene is discharged from the discharge port,
This is not preferable because the yield of purified polypropylene decreases.

By carrying out the method of the present invention, polypropylene can be efficiently purified using extremely simple equipment and has high industrial value.

The effects of the present invention will be specifically explained below using Reference Examples, Examples, and Comparative Examples, but the present invention is not limited thereto.

Reference Example Manufacture of Polypropylene Slurry A nine-vibration mill equipped with four grinding pots each having an internal volume of 4 tons each containing 9 tons of steel balls with a diameter of 121 m was prepared. Magnesium chloride 300F and orthoacetate ethyl 40-11.2-dichloroethane 60- were charged into each pot under a nitrogen atmosphere and pulverized for 40 hours. Thoroughly dried and placed in a nitrogen atmosphere 50
3 kg of the above pulverized material and fl' tetrachloride were placed in autoclave No. 1.
720t was charged and stirred at 80°C for 120 minutes, then stopped and the supernatant liquid was removed. Next, add 35t of n-hebutane and
After stirring at 0° C. for 15 minutes, the mixture was allowed to stand still, and the supernatant liquid was removed by washing, which was repeated 7 times. After death, 20 tons of n-hebutane was further added to prepare a solid catalyst slurry. When a portion of the solid catalyst slurry was sampled and analyzed by evaporation, it was found that the solid catalyst contained 1.62% by weight of N.

Propylene was charged at 1000 Kf into a jacketed 5-size autoclave which had been thoroughly dried, purged with nitrogen, and further purged with propylene.

Separately, in a 5 t flask, 112 t of n-heptane 41゜diethylaluminum chloride 192-1p-)methyl ruylate was added to the solid catalyst 401 gold, and after stirring at room temperature for 1 minute, triethylaluminum 4o- was added. It was press-fitted into a No. 5 autoclave. Next, add 1 hydrogen
．． Then, the internal temperature was raised to 75°C by passing hot water through the jacket, and polymerization was continued while maintaining the temperature at 75°C while introducing hydrogen so that the hydrogen concentration remained constant.

On the other hand, a solution of 120 mm of triethylaluminum in 2,280 mm of n-heptane was continuously pressurized into the autoclave at 20 mm/-, and polymerized for 2 hours while charging liquid propylene at a ratio of 5:9/-. . Thereafter, three or more diethylene glycol monoisopropyl ether were added to stop the polymerization. Then stir at 70℃; 6! c) 6ooKt polypropylene/10o
o Kg propylene slurry.

Example 1 An experiment was conducted using a countercurrent washing tower of the type shown in FIG. The countercurrent cleaning tower has an inner diameter of 30mm at the narrow part and 50mm at the thicker part.
C1lI, length of thin part 10m1 length of thick part 2
m, the lower cone is divided into three stages as shown in c, and i, b, and c are arranged so that they do not coincide as shown in Figure 2 when observed in the vertical direction. be. The cross-sectional area of the divided parts is Yumu~EΔヱ=176.
66n''.On the other hand, propylene is introduced as a cleaning liquid from the cleaning liquid introduction nozzle 3 at the bottom, but the nozzle is
The piping shown in the figure has 12 holes.

The washed slurry is discharged from the slurry discharge nozzle 4, passes through the heating tube 6, and is separated under reduced pressure by the cyclone T.
Propylene is removed and collected in the popper 8. Further, the cleaning liquid is discharged through the cleaning liquid discharge nozzle 2 and removed from the system.

Using the above equipment, the slurry obtained in the reference example was heated to 320K.
p/h, polypropylene and 4/h are introduced into the ladder 120 from nozzle 1, and propylene for cleaning is introduced from nozzle 3 at 420 p/h.
It will be introduced at 019/h. On the other hand, the slurry discharge nozzle
The plant emits 120Kf/hsx9 of polypropylene at 30,014/h. The experiment continued for 1 hour while controlling propylene to be extracted at 440 hA from the exhaust nozzle 2 on the upper part.

A part of the slurry made in the reference example was sipe-IJed, and after drying, the intrinsic viscosity of the lag, (hereinafter abbreviated as Fη) boiling n
-Heptane extraction residue, (-Yarimushi) color 21 L: 10-
Calculated as x 1o OX, pre-extraction polymer (hereinafter abbreviated as II) iu * MF was analyzed.

On the other hand, in Reference Example, the stirring of the autoclave was stopped, the supernatant was taken out, and the nonvolatile content (dissolved polymer and dissolved ash), A/, and A4 were analyzed. Also about the powder taken out from Botsuno (-8!!, Ma, #5Ai
b was analyzed. The results are shown in Table 19.

Measurements of M and rod in the powder and μ, rod in the supernatant,
Calculated from nonvolatile matter, the amount dissolved in propylene is 1.4% of the total polymer, and the amount dissolved in propylene is 1.4% of the total polymer.
It is.

On the other hand, when calculated from the measured values of purified polypropylene, the remaining percentage of the dissolved portion in the polymer is approximately 90% removed.

Comparative example 1 Vertical partition plates a, b in the countercurrent washing tower.

The experiment was conducted in the same manner as in Example 1, except that C was removed, and the powder obtained from Example 8 was analyzed in the same manner.

The results are shown in Table 1. -Also, when calculated in the same manner as in the examples, the residual rate of the dissolved portion in the polymer is only about 60% removed.

Example 2 2.6-di-t-butyl 4- was added to the powder obtained in Example 1.
Methyl-phenol vs. powder 20/10ooo
A T-die film was made by adding t/. Make 5 sets of 2 sheets of T-die film (120sm x 80m x 30μ), put 2 to 300g on it, leave it at 50℃ for 24 hours and 7 hours, and then
When measuring the adhesion area of stacked films, the average of 5 films was 8.
%Met. Meanwhile, the above film was soaked in hot water at 70℃ for 24 hours.
After treatment for a period of time and drying at 30°C, the flat surface was observed, but there was no particular change.

Comparative Example 2 A film was made from the powder of Comparative Example 1 in the same manner as in Example 2, and the adhesion area was measured to be 35%. Dad, when I treated it with 70℃ water for 24 hours, the plane of the film was slightly wavy.

[Brief explanation of the drawing]

FIG. 1 shows a longitudinal sectional view of an example of the countercurrent washing tower equipment of the present invention. In the figure 1...Slurry introduction nozzle 2...Cleaning liquid discharge nozzle 3...Cleaning liquid introduction nozzle 4...Slurry discharge nozzle 5...Slurry dispersion cone 6...Heating tube, T... Cyclone, 8...hopper, a, b, e represent partition plates.゛Figure 2 shows a cross-sectional view of the partition plates a, b, and c, and Figure 3 shows a cross-sectional view of the cleaning liquid introduction nozzle. Applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Scope of Claims] 1) Polypropylene obtained by bulk polymerization using propylene itself as a medium or by copolymerizing propylene and other α-olefins is processed using a countercurrent washing tower to mainly produce propylene. In the method of purification by countercurrent washing using a cleaning liquid as a component, a partition plate is provided in the vertical direction of the countercurrent washing tower, and the cross-sectional area of the part surrounded by the vertical partition plate is 250 cd or less Using a countercurrent cleaning tower with a vertical length longer than lO×r (the cross-sectional area of the part surrounded by the plate), and controlling the rising speed of the cleaning solution at the interface between the slurry and the cleaning solution, A method for refining polypropylene, which is characterized by controlling the conditions such that the polypropylene is produced. 2) dividing a vertical partition plate into two or more pieces in the vertical direction,
The purification method according to claim 1, wherein the partition plates are provided so that the partition plates divided into two or more pieces do not coincide when observed in the vertical direction. 3) Fine purification of polypropylene obtained by bulk polymerization using propylene itself as a medium or by copolymerizing propylene with other α-olefins by countercurrent washing using a countercurrent washing tower. In the method of
1. A countercurrent cleaning device comprising a partition plate in the vertical direction of a washing tower, and a cross-sectional area of a portion surrounded by the partition plate is 250 cIII or less and longer than the length in the vertical direction. 4) The countercurrent cleaning device according to claim 3, wherein the partition plate is vertically divided into two or more parts, so that when the divided partition plates are observed in the vertical direction, they do not coincide. 5) A countercurrent cleaning device according to claim 3 or 4, in which a conical dispersion body 5 is provided in the direction F of the polypropylene introducing nozzle 1 to be cleaned. 6) A countercurrent cleaning device according to any one of claims 3, 4, and 5, wherein the cleaning liquid introduction nozzle 3 is a water pipe having a large number of holes.