JPH0651771B2 - Method for continuously producing propylene block copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a continuous production method of a propylene block copolymer, and more specifically, the present invention has an excellent quality balance such as impact resistance, rigidity and processability. The present invention relates to a method for producing the copolymer with high productivity.

[Prior art and its problems] Crystalline polypropylene produced by polymerizing propylene using a stereoregular catalyst has excellent properties such as rigidity and heat resistance, but has low impact strength especially at low temperature. However, the range of use was practically limited. Therefore, as a method for improving this drawback, a propylene homopolymer or a copolymer of propylene and another α-olefin is produced in the first step, and a copolymerization of propylene and ethylene or another α-olefin is performed in the second step. Many so-called block copolymerization methods for producing a coalescence have been proposed.

Generally, the block copolymer has a different ratio of the first stage polymerized portion and the second stage copolymerized portion depending on its use.

Conventionally, in the vapor phase continuous production method of a block copolymer,
As a method of controlling this polymerization ratio in the front and rear stages, change of polymerization conditions such as polymerization pressure, polymerization temperature or increase / decrease in the amount of polymer retained in the reactor (which leads to increase / decrease in residence time of the catalyst in the reactor) And the supply of a trace amount of polymerization activity inhibitor.

However, in the case of continuously producing a polymer having a composition in which the copolymerization ratio is extremely different between the first stage and the second stage, it is inevitable to significantly change the production condition for each stage, which greatly reduces the space-time yield. It is indispensable and has a drawback that it takes a long time to obtain a desired composition (block copolymer).

In addition, to produce from a low copolymerization ratio to a high copolymerization ratio in a reactor having the same volume in each stage, only by changing the polymerization conditions such as pressure, the gas condensation problem and the polymer outside the reaction vessel can be changed. Due to problems such as entrainment of droplets, it is difficult to stably produce a block copolymer having excellent quality.

On the other hand, carbonyl sulfide, oxygen, water, carbon monoxide, carbon dioxide, alcohol and the like can be exemplified as the regulator when the polymerization ratio is adjusted by supplying the polymerization activity inhibitor to the copolymerization reaction system. For example, a method of adding an oxygen-containing compound and an active hydrogen compound to a copolymerization reaction system is disclosed in JP-A-61-6.
9821, proposed in JP-A-61-69822. The methods proposed therein are mainly intended to prevent the adhesion of the polymer to a container or the like by adding a small amount of the above compound to the copolymerization system.

On the other hand, an attempt to positively supply the above compound to the copolymerization reaction system to control the copolymerization activity has a drawback in that the fluidity of the polymer is deteriorated, the quality is deteriorated, and the safety is not preferable.

[Problems to be Solved by the Invention] The present inventors have supplied hydrogen sulfide to the copolymerization reaction system of the second stage in a controlled amount, thereby changing the polymerization pressure, the polymerization temperature conditions and the like, Control the copolymerization reaction activity,
We have discovered that we can make a quick grade change.

The present invention, in the gas phase continuous production of propylene / α-olefin block copolymer, by controlling the conventional polymerization pressure, polymerization temperature and the amount of polymer retained in the reactor, the polymerization ratio of the block copolymer Unlike the method of changing,
A minute amount of hydrogen sulfide is supplied to the copolymerization section in the second stage, and the reaction amount of the copolymerization section is controlled by adjusting the supply amount, and a composition having a high copolymerization ratio is changed to a composition having a low copolymerization ratio. It is a polymerization method capable of producing a block copolymer without changing the polymerization pressure and the like.

As is clear from the above description, the object of the present invention is a continuous production method of a propylene block copolymer using a stereoregular catalyst, and the problems of the prior art include impact resistance, rigidity and processing by using hydrogen sulfide. It is intended to provide a method for continuously producing various copolymers having different copolymerization ratios with good productivity without causing a disadvantageous decrease in quality balance such as properties and deterioration of fluidity of the polymer. .

[Means for solving problems]

 The present invention has the following main configuration (1).

(1) Titanium-containing solid catalyst component (A) and general formula AlR ² mX _3
- m (wherein ^{R 2} represents a hydrocarbon having 1 to 20 carbon atoms, X
Represents a halogen atom and m represents a number of 3m> 1.5), and a stereoregular catalyst in combination with an organoaluminum compound (B) represented by In the presence of the polymerization reaction mixture obtained in the first stage as the second stage, propylene and other α-olefins are produced.
Polymerization ratio (weight ratio) by supplying olefin to the copolymerization reaction system
A vapor phase continuous process for producing a propylene block copolymer, comprising copolymerizing at a ratio of 10/90 to 90/10, wherein titanium in a stereoregular catalyst is used in the second step of copolymerization.
Hydrogen sulfide is supplied to the second step copolymerization reaction system at a ratio of 0.001 to 0.5 mol per 1 g atom, and the copolymerization reaction activity of the second step catalyst is increased from 5% to 95% when the hydrogen sulfide is not supplied. A method for continuous vapor phase production of a propylene block copolymer, which is characterized by controlling.

The structure and effect of the present invention will be described in detail below.

As the titanium-containing solid component (A) used in the present invention,
There is no particular limitation as long as it is a solid catalyst containing titanium,
A highly active reduced titanium trichloride obtained by reducing titanium tetrachloride with organic aluminum and further treating it with an electron-donating compound and an electron-accepting compound, etc., and bringing it into contact with a magnesium compound and an electron-donating compound So-called highly active catalysts such as supported catalysts obtained by the above are preferable. This is because the supply of hydrogen sulfide lowers the catalytic activity, and it is easier to deash the copolymer after polymerization by using a catalyst having high activity in advance.

As the organic aluminum compound (B), a general formula AlR ² m
X _{3m (wherein} R ² represents a hydrocarbon group having 1 to 20 carbon atoms, X represents a halogen atom, m is a number of 3m> 1.5) compounds represented by is used. For example, diethyl aluminum chloride, triethyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tri-n-hexyl aluminum, diethyl bromide, diethyl iodide and the like can be used alone or in combination.

Furthermore, in addition to the titanium-containing solid component (A) and the organoaluminum compound (B), compounds generally used as the catalyst third component such as an electron donating compound can be used.

Examples of the compound include ethers such as diethyl ether, di-n-butyl ether, di-iso-amyl ether and diphenyl ether, and carboxylic acid esters such as methyl formate, ethyl acetate, ethyl benzoate, ethyl toluate and methyl methacrylate. , Ketones such as methyl ethyl ketone and acetophenone, aldehydes such as acetaldehyde, isobutyraldehyde and benzaldehyde, diethylamine, aniline, acetonitrile, acrylic acid amide,
Nitrogen-containing compounds such as tetramethylurea, phosphorus-containing compounds such as triphenylphosphine, triphenylphosphite and triphenylphosphate, carbon disulfide, sulfur-containing compounds such as methylphenylsulfone, diphenyldimethoxysilane, ethyltrimethoxysilane, methyl Examples thereof include organic silicon compounds such as ethyldimethoxysilane, triethylmethoxysilane, trimethylethoxysilane, phenyltrimethoxysilane, and methylphenyldimethoxysilane.

In the present invention, in the first step, a propylene polymer or copolymer is produced in the gas phase. At this stage, the polymerization may be carried out in two or more steps. Prior to full-scale polymerization, the catalyst may be prepolymerized with a small amount of α-olefin such as propylene or ethylene for the purpose of improving fluidity.

The first stage polymerization is usually at a polymerization temperature of 30 to 100 ° C, preferably 50 to 75 ° C, and a polymerization pressure of 10 to 50 kg / cm ² -G, preferably 10 to 30 kg / cm ² -G. It can be illustrated.
Hydrogen is usually used to control the molecular weight and is carried out with a melt index MI = 0.1-300. The monomer supply composition in the first stage is ethylene (▲ C ⁼ ₂ ▼) or α-olefin / {ethylene (▲ C ⁼ ₂ ▼) or α-
It is carried out with olefin + propylene (▲ C ⁼ ₃ ▼)} = 0 to 5 wt%. If the amount of ethylene or other α-olefin is more than 5 wt%, there is a drawback that the physical properties such as rigidity and heat resistance, which are characteristics of polypropylene, are deteriorated. The polymerization amount in the first stage is 40 to 95% by weight, preferably 65 to 90% by weight, based on the total amount of the propylene block copolymer finally obtained. The polymerization reaction mixture that has completed the first stage is sent to the polymerization process of the second stage.

In the present invention, random copolymerization is carried out in the second step in the presence of the polymerization reaction mixture obtained in the previous step at a ratio of propylene and another α-olefin polymerization ratio (weight ratio) of 10/90 to 90/10. Since the random copolymerization is carried out by gas phase polymerization, the whole copolymer is incorporated in the block copolymer, which is industrially advantageous because the yield with respect to the consumed olefin is high.

Other α-olefins used for random copolymerization include ethylene, 1-butene, 1-pentene, 1-hexene, 4-
Examples include methyl-1-pentene and 1-octene. The copolymerization ratio of propylene and other α-olefins is 10 by weight.
/ 90 to 90/10, preferably 30/70 to 70/30.

In the random copolymerization, hydrogen sulfide is used in a proportion of 0.001 to 0.5 g atom, preferably 0.01 to 0.3 g atom, per 1 g atom of titanium in the stereoregular catalyst. By changing the ratio of the amount of hydrogen sulfide supplied to titanium atoms, the reaction activity of the copolymerization system can be controlled at a ratio of 5% to 95% without changing the polymerization conditions such as the polymerization pressure. To supply hydrogen sulfide to the random copolymerization system, it may be directly introduced into the polymerization reactor, but it is more effective to introduce it after premixing it with the gaseous polymerization raw material to be supplied to the reaction vessel. Is.

Hereinafter, the present invention will be described with reference to examples.

Example 1 1) Preparation of catalyst n-hexane 6, 5.0 mol of diethylaluminum monochloride (DEAC) and 12.0 mol of diisoamyl ether were added to 25 mol.
The mixture was mixed at 5 ° C. for 5 minutes and reacted at the same temperature for 5 minutes to obtain a reaction solution (I) (diisoamyl ether / DEAC molar ratio 2.4).

40 mol of titanium tetrachloride was placed in a nitrogen-substituted reactor with a stirrer and heated to 35 ° C., and the whole amount of the reaction product liquid (I) was added dropwise to this in 180 minutes, and then kept at the same temperature for 30 minutes, and 75 ° C.
The temperature was raised to 0 ° C., the reaction was continued for 1 hour, the mixture was cooled to room temperature, the supernatant was removed, and n-hexane 30 was added and decantation was repeated 4 times to obtain 1.9 kg of a solid product (II). It was

The total amount of this (II) was suspended in n-hexane 30 at 20 ° C. to obtain 1.6 kg of diisoamyl ether and 3.5 mg of titanium tetrachloride.
kg was added at room temperature for about 5 minutes and reacted at 65 ° C. for 1 hour. After the reaction was completed, the mixture was cooled to room temperature (20 ° C), the supernatant was removed by decantation, 30 n-hexane was added, and the mixture was stirred for 15 minutes and left standing to remove the supernatant, which was repeated 5 times. After that, it was dried under reduced pressure to obtain a solid product (III).

2) Preparation of catalyst A tank having an internal volume of 100 was charged with 80 g of n-hexane, 80 g of diethylaminium chloride, and 1.8 kg of the above solid product, and then while maintaining stirring at 30 ° C., ethylene gas was added at 5 g at 360 g / H.
It was supplied for an hour and pretreated.

3) Polymerization method An explanation will be given based on the flow sheet shown in FIG.

12 g / H of the above solid product and 250 g / H of a 15 wt% n-hexane solution of diethylaluminum chloride were continuously fed into the horizontal type polymerization vessel 1 of L / D = 5 equipped with a stirrer having a reaction volume of 850. Further, hydrogen was supplied through the gas circulation pipe 2.
The reaction conditions are temperature 70 ° C, pressure 25 kg / cm ² G, stirring speed.
It was kept at 20 rpm. The heat of reaction was offset by the heat of vaporization of the raw material propylene supplied from the pipe 3. The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through the pipe 4 and was returned to the main polymerization step.

The propylene polymer obtained in this step was withdrawn from the polymerization vessel through the pipe 5 so that the retained level of the polymer would be 50% by volume of the reaction volume.

In the copolymerization process, the reaction volume is 850 L / D with a stirrer.
= 5 was used to carry out copolymerization of ethylene and propylene.

The reaction conditions are stirring speed 20 rpm, temperature 70 ° C, pressure 22 kg / cm ^2.
G, gas phase gas composition: propylene 57mol%, ethylene 31m
It was ol%, propane 9 mol%, and H ₂ 3 mol%. Hydrogen sulfide was supplied from the hydrogen gas pipe 7 at a rate of 23 cc / H in order to reduce the activity of the copolymerization reaction. The heat of reaction was offset by the heat of vaporization of the raw material propylene supplied from the pipe 6.

The unreacted gas discharged from the polymerizer was cooled and condensed outside the reactor system through the pipe 8 and was returned to the main copolymerization step.

The propylene-ethylene block copolymer obtained by this copolymerization was withdrawn from the polymerization vessel through a pipe 9 so that the level of the retained polymer was 50% by volume of the reaction volume. In this copolymerization process, the ratio of the polymerization amount of propylene and ethylene is 40
wt% and ethylene 60 wt%.

The polymerization ratio between the propylene polymerization step and the main copolymerization step was 81 wt% for the propylene polymerization step and 19 wt% for the main copolymerization step. The reaction conditions of this example and the composition of the obtained block copolymer are shown in Table 1.

Example 2 The procedure of Example 1 was repeated, except that the amount of hydrogen sulfide supplied to the copolymerization reactor was different. The reaction conditions and the composition of the obtained block copolymer are shown in Table 1.

Example 3 Example 1 was repeated except that the amount of hydrogen sulfide supplied to the copolymerization reactor was different. The reaction conditions and the composition of the obtained block copolymer are shown in Table 1.

Example 4 Example 3 was repeated. However, the main difference is that an electron donating compound is used. The reaction conditions and the composition of the obtained block copolymer are shown in Table 1.

Comparative example 1 It carried out like Example 4. However, the main differences are that, as shown in Table 1, the amount of polymer retained in the propylene polymerization step and the block copolymerization step, the pressure and temperature in the copolymerization step, and that hydrogen sulfide is not supplied to the copolymerization reactor.

In this method, the amount of the polymer retained in the propylene polymerization step is large, the amount of the polymer entrained outside the reactor system is large, and the polymer retention level is low in the copolymerization step, so that the polymer adheres to the stirring blade. It is not preferable because it increases. Furthermore, in the copolymerization process, the condensation temperature of the gas discharged from the reactor becomes 15 ° C or lower,
It is not preferable because a considerably cooled medium is required for gas condensation.

Example 5 1) Production of catalyst Purified decane 3, anhydrous magnesium chloride in a reactor
480 g, n-butyl orthotitanate 1700 g and 2-ethyl-1
-Mix 1950g hexanol and stir to 130 ℃ 1
It was heated and dissolved for a period of time to form a uniform solution. The homogeneous solution
Diisobutyl phthalate (180 g) was added with stirring at 70 ° C., and after 1 hour, 5200 g of silicon tetrachloride was added dropwise over 2.5 hours to precipitate a solid, and the mixture was further heated at 70 ° C. for 1 hour.
The solid was separated from the solution and washed with purified hexane to give a solid product (I). The total amount of the solid product (I) was mixed with 5000 ml of titanium tetrachloride dissolved in 5000 ml of 1,2-dichloroethane, 180 g of diisobutyl phthalate was subsequently added, and the mixture was reacted at 100 ° C. for 2 hours while stirring, and then at the same temperature. At
Remove the liquid phase by decantation, add again 5000 ml of 1,2-dichloroethane and 5000 ml of titanium tetrachloride,
The mixture was stirred at 0 ° C for 2 hours and washed with purified hexane to give a solid product (II). The solid product (II) was made into a suspension of purified hexane without drying. It was present in suspension 1 in the proportion of 3000 g of solid product (II).

All of the above operations were performed under a purified nitrogen atmosphere. The composition analysis result of the solid product (II) is Ti2.8wt%, Cl55.6wt
%, Mg 16.5 wt%, butoxy group 3.8 wt%, ethylhexanoxy group 1.1 wt% and diisobutyl phthalate 15.2 wt%.

2) Polymerization method The polymerization method of Example 1 was repeated. However, the main difference is that the above solid product is 0.9 g / H as the solid product and triethylaluminum is the organic aluminum compound.
3.4 g / H and 1.2 g / H of diphenyldimethoxysilane as an electron donating compound were continuously supplied. Also, the amount of hydrogen sulfide supplied to the copolymerizer is different. The reaction conditions and the composition of the obtained block copolymer are shown in Table 1.

[Brief description of drawings]

FIG. 1 is a flow sheet of the apparatus used in the embodiment of the present invention. FIG. 2 is a flow sheet showing the method of the present invention.

Claims (1)

[Claims] 1. A solid catalyst component (A) containing titanium and a general formula Al.
R ² mX _{3m (wherein} ^{R 2} represents a hydrocarbon having 1 to 20 carbon atoms, X represents a halogen atom, m is a number of 3m> 1.5) an organoaluminum compound represented by (B)
Using a stereoregular catalyst in combination with the above, a propylene homopolymer or a copolymer of propylene and another α-olefin was produced as the first step, and the polymerization obtained in the first step as the second step. In the presence of the reaction mixture, propylene and another α-olefin are supplied to the copolymerization reaction system and copolymerized at a polymerization ratio (weight ratio) of 10/90 to 90/10 to obtain a propylene block copolymer. In the vapor phase continuous production method, titanium in the stereoregular catalyst is used in the copolymerization in the second step.
Hydrogen sulfide is supplied to the second stage copolymerization reaction system at a ratio of 0.001 to 0.5 mol per 1 g atom, and the copolymerization reaction activity of the second stage catalyst is 5% to 95% when the hydrogen sulfide is not supplied. A continuous vapor phase production method of a propylene block copolymer, characterized in that